Ibrahim Ahmed Akkouh

• Ystaas, Lars A.R.; Parekh, Pravesh; Parker, Nadine; Akkouh, Ibrahim Ahmed; Birkenæs, Viktoria & Sønderby, Ida Elken [Show all 12 contributors for this article] (2026). Genetic liability to addiction underlies comorbid bipolar and substance use disorders. Biological Psychiatry. ISSN 0006-3223. doi: 10.1016/j.biopsych.2026.08.008. Full text in Research Archive
• Mlakar, Vid; Forti, Marta Di; Halff, Els F.; Srivastava, Deepak P.; Akkouh, Ibrahim Ahmed & Djurovic, Srdjan [Show all 13 contributors for this article] (2026). Health behaviours and telomere biology in severe mental disorders. Translational Psychiatry. 16(1). doi: 10.1038/s41398-026-04362-2. Full text in Research Archive Show summary

  Alterations in telomere length (TL), a marker of cellular ageing, have been reported in individuals with severe mental disorders (SMD). Epidemiological studies of the general population have highlighted that unhealthy lifestyles may exacerbate telomere attrition. However, the impact of lifestyle on TL within the context of SMD remains unexplored. The study consisted of 410 participants (schizophrenia spectrum [n = 225] and affective disorder [n = 185]) collected as part of the Norwegian Thematically Organised Psychosis (TOP) study. Leukocyte TL was measured via blood and determined by quantitative real-time Polymerase Chain Reaction (qPCR). Patients provided self-report data on six lifestyle domains including: diet, exercise, smoking, alcohol consumption, substance use, and coffee consumption. A global dichotomised (healthy vs unhealthy) lifestyle variable was created, as well as a health behaviour variable, indicating the level of unhealthy behaviours. Individuals with an unhealthy lifestyle had shorter TL compared to those with a healthy lifestyle (Cohen’s d = 0.58, F = 8.62, p = 0.004). A relationship was observed between increasing number of unhealthy behaviours and shorter TL (F = 2.69, p = 0.02), adjusted for age, sex, ethnicity, trauma exposure, medication daily defined dose (DDD), years of education and diagnosis. In terms of base-pair loss, individuals with healthy lifestyles exhibited a roughly 6-year lower biological age, compared to individuals with unhealthy lifestyles. Our study indicates that a healthier lifestyle is associated with longer TL in SMD. This highlights the importance of health behaviours as potential clinical targets for ensuring healthier cellular ageing in psychiatric populations.

• Assis, Denis Reis de; Pentz, Atle Bråthen; Osete, Jordi Requena; Ievglevskyi, Oleksandr; Vandenberghe, Matthieu & Akkouh, Ibrahim Ahmed [Show all 12 contributors for this article] (2026). Investigating neural impairments in psychotic disorders using electroencephalography and cortical spheroids. Translational Psychiatry. 16(1). doi: 10.1038/s41398-026-03863-4. Full text in Research Archive Show summary

  Synaptic dysfunction is a candidate mechanism in psychotic disorders, yet the precise underlying substrates remain elusive. We investigated how combining in vivo electroencephalography (EEG) and in vitro human cortical spheroid (hCS)-based methods can further our understanding of psychosis pathophysiology during fetal stages of neurodevelopment. Ten individuals with schizophrenia (SZ) or bipolar disorder (BD; 5 males and 5 females) and five controls (CTRL; 3 males and 2 females) underwent EEG assessments, including long-term potentiation (LTP)-like cortical plasticity and mismatch negativity (MMN). hCS were generated from induced pluripotent stem cells of all participants, and immunohistochemistry, Seahorse bioenergetics and patch-clamp recordings were performed. EEG-based LTP-like plasticity was reduced in individuals with SZ and BD. Basal respiration was decreased in BD hCS and VGLUT1 levels were reduced in both SZ and BD hCS. There was a positive association between EEG-based LTP-like plasticity and hCS basal respiration which survived correction. Our data provide further support for roles of mitochondrial and glutamatergic impairments in the synaptic dysfunction of psychosis and demonstrate the potential of combining EEG- and hCS-based methods for early development mechanistic studies of brain disorders.

• Eissa, Ahmed; Fredrik Kismul, Jan; Pentz, Atle Bråthen; Elvsåshagen, Torbjørn; Metzner, Christoph & Akkouh, Ibrahim Ahmed [Show all 12 contributors for this article] (2026). Computational Modelling of Novelty Detection in the Mismatch Negativity Protocols and Its Impairments in Schizophrenia. European Journal of Neuroscience. ISSN 0953-816X. 63(6). doi: 10.1111/ejn.70453. Full text in Research Archive
• Mlakar, Vid; Forti, Marta Di; Halff, Els F.; Srivastava, Deepak P.; Akkouh, Ibrahim Ahmed & Djurovic, Srdjan [Show all 13 contributors for this article] (2025). Coffee intake is associated with telomere length in severe mental disorders. BMJ Mental Health. 28(1). doi: 10.1136/bmjment-2025-301700. Full text in Research Archive
• Akkouh, Ibrahim Ahmed; Osete, Jordi Requena; Szabo, Attila; Andreassen, Ole & Djurovic, Srdjan (2025). Neurobiological Perturbations in Bipolar Disorder Compared With Schizophrenia: Evidence From Cell Cultures and Brain Organoids. Biological Psychiatry. ISSN 0006-3223. 98(4), p. 322–332. doi: 10.1016/j.biopsych.2025.02.012. Full text in Research Archive Show summary

  Bipolar disorder (BD) and schizophrenia (SCZ) are uniquely human disorders with a complex pathophysiology that involves adverse neuropathological events in brain development. High disease polygenicity and limited access to live human brain tissue make these disorders exceedingly challenging to study mechanistically. Cellular cultures and brain organoids generated from human-derived pluripotent stem cells preserve the genetic background of the donor cells and recapitulate some of the defining characteristics of human brain architecture and early spatiotemporal development. These model systems have already proven successful in deciphering some of the neuropathological perturbations in BD and SCZ, and methodological advancements, such as the functional integration of 2 or more region-specific organoids and organoid transplantation in animals, promise to deliver increasingly refined insights. Here, we review a selection of recent discoveries achieved by stem cell–based models, with a particular focus on patterns of cellular and molecular convergence and divergence between BD and SCZ. First, we provide a brief overview of the evidence from glial and neuronal cell cultures and brain organoids, centering our discussion on several key functional domains, including neuroinflammation, neuronal excitability, and mitochondrial function. Then, we review recent findings demonstrating the power of integrating stem cell–based systems with gene editing technologies to elucidate the functional consequences of risk variants identified through genetic association studies. We end with a discussion of current challenges and some promising avenues for future research.

• Mlakar, Vid; Akkouh, Ibrahim Ahmed; Halff, Els F.; Srivastava, Deepak P.; Birkenæs, Viktoria & Ueland, Torill [Show all 12 contributors for this article] (2024). Telomere biology and its maintenance in schizophrenia spectrum disorders: Exploring links to cognition. Schizophrenia Research. ISSN 0920-9964. 272, p. 89–95. doi: 10.1016/j.schres.2024.08.011. Full text in Research Archive Show summary

  Objective Contemporary research suggests reduced telomere length in schizophrenia spectrum disorders (SZ) compared to age-adjusted non-affected individuals. However, the role of telomere maintenance and telomere repair in SZ is poorly understood as well as the involvement of telomere biology in cognitive abnormalities in SZ. Methods The study consisted of 758 participants (SZ [n = 357] and healthy controls, HC [n = 401]) collected as part of the Norwegian TOP study. Participants were assessed with standardized neuropsychological tests measuring five cognitive domains. Leucocyte telomere length (TL) was measured via blood and determined by quantitative real-time Polymerase Chain Reaction (qPCR) providing a telomere to single copy ratio (T/S ratio), used to estimate the mean telomere length. Telomerase activity was assessed by the expression levels of the Telomerase Reverse Transcriptase (TERT) and Telomerase RNA Component (TERC) genes. To assess telomere maintenance and telomere repair we calculated the telomerase expression to TL ratio (TERT/TL and TERC/TL respectively). Results Patients had reduced TERT (F = 5.03, p = 0.03), but not TERC expression (F = 1.04, p = 0.31), and higher TERT/TL (F = 6.68, p = 0.01) and TERC/TL (F = 6.71, p = 0.01), adjusted for age, sex, and ethnicity. No statistically significant association was observed between any of the telomere biology markers and the cognitive domains (p > 0.05). Conclusion Our study shows changes in TERT expression and telomere maintenance and telomere repair in SZ compared HC. However, the role of telomere biology in the mechanism underlying cognitive impairment in psychosis seems limited.

• Szabo, Attila; O'Connell, Kevin Sean; Akkouh, Ibrahim Ahmed; Ueland, Thor; Sønderby, Ida Elken & Hope, Sigrun [Show all 16 contributors for this article] (2024). Elevated levels of peripheral and central nervous system immune markers reflect innate immune dysregulation in autism spectrum disorder. Psychiatry Research. ISSN 0165-1781. 342. doi: 10.1016/j.psychres.2024.116245. Full text in Research Archive Show summary

  Background Evidence suggests dysregulated immune functions in the pathophysiology of Autism spectrum disorder (ASD), although specific immune mechanisms are yet to be identified. Methods We assessed circulating levels of 25 immune/neuroinflammatory markers in a large ASD sample (n = 151) and matched controls (n = 72) using linear models. In addition, we performed global brain transcriptomics analyses of relevant immune-related genes. We also assessed the expression and function of factors and pathway elements of the inflammasome system in peripheral blood mononuclear cells (PBMC) isolated from ASD and controls using in vitro methods. Results We found higher circulating levels of IL-18 and adhesion factors (ICAM-1, MADCAM1) in individuals with ASD relative to controls. Consistent with this, brain levels of ICAM1 mRNA were also higher in ASD compared to controls. Furthermore, we found higher expression/activity of Caspase-1 and the inflammasome sensor NLRP3 in PBMCs in ASD, both at baseline and following inflammatory challenge. This corresponded with higher levels of secreted IL-18, IL-1β, and IL-8, as well as increased expression of adhesion factors following inflammasome activation in ASD PBMC cultures. Inhibition of the NLRP3-inflammasome rescued the observed immune phenotype in ASD in vitro. Conclusion Our results suggest a role for inflammasome dysregulation in ASD pathophysiology.

• Sæther, Linn Sofie; Szabo, Attila; Akkouh, Ibrahim Ahmed; Haatveit, Beathe; Mohn, Christine & Vaskinn, Anja [Show all 14 contributors for this article] (2024). Cognitive and inflammatory heterogeneity in severe mental illness: Translating findings from blood to brain. Brain, Behavior, and Immunity. ISSN 0889-1591. 118, p. 287–299. doi: 10.1016/j.bbi.2024.03.014. Full text in Research Archive Show summary

  Recent findings link cognitive impairment and inflammatory-immune dysregulation in schizophrenia (SZ) and bipolar (BD) spectrum disorders. However, heterogeneity and translation between the periphery and central (blood-to-brain) mechanisms remains a challenge. Starting with a large SZ, BD and healthy control cohort (n = 1235), we aimed to i) identify candidate peripheral markers (n = 25) associated with cognitive domains (n = 9) and elucidate heterogenous immune-cognitive patterns, ii) evaluate the regulation of candidate markers using human induced pluripotent stem cell (iPSC)-derived astrocytes and neural progenitor cells (n = 10), and iii) evaluate candidate marker messenger RNA expression in leukocytes using microarray in available data from a subsample of the main cohort (n = 776), and in available RNA-sequencing deconvolution analysis of postmortem brain samples (n = 474) from the CommonMind Consortium (CMC). We identified transdiagnostic subgroups based on covariance between cognitive domains (measures of speed and verbal learning) and peripheral markers reflecting inflammatory response (CRP, sTNFR1, YKL-40), innate immune activation (MIF) and extracellular matrix remodelling (YKL-40, CatS). Of the candidate markers there was considerable variance in secretion of YKL-40 in iPSC-derived astrocytes and neural progenitor cells in SZ compared to HC. Further, we provide evidence of dysregulated RNA expression of genes encoding YKL-40 and related signalling pathways in a high neuroinflammatory subgroup in the postmortem brain samples. Our findings suggest a relationship between peripheral inflammatory-immune activity and cognitive impairment, and highlight YKL-40 as a potential marker of cognitive functioning in a subgroup of individuals with severe mental illness.

• Szabo, Attila; Akkouh, Ibrahim Ahmed; Osete, Jordi Requena; Assis, Denis Reis de; Kondratskaya, Elena & Hughes, Timothy [Show all 9 contributors for this article] (2024). NLRP3 inflammasome mediates astroglial dysregulation of innate and adaptive immune responses in schizophrenia. Brain, Behavior, and Immunity. ISSN 0889-1591. 124, p. 144–156. doi: 10.1016/j.bbi.2024.11.030. Full text in Research Archive Show summary

  Mounting evidence indicates the involvement of neuroinflammation in the development of schizophrenia (SCZ), but the potential role of astroglia in this phenomenon remains poorly understood. We assessed the molecular and functional consequences of inflammasome activation using induced pluripotent stem cell (iPSC)-derived astrocytes generated from SCZ patients and healthy controls (CTRL). Screening protein levels in astrocytes at baseline identified lower expression of the NLRP3-ASC complex in SCZ, but increased Caspase-1 activity upon specific NLRP3 stimulation compared to CTRL. Using transcriptional profiling, we found corresponding downregulations of NLRP3 and ASC/PYCARD in both iPSC-derived astrocytes, and in a large (n = 429) brain postmortem case-control sample. Functional analyses following NLRP3 activation revealed an inflammatory phenotype characterized by elevated production of IL-1β/IL-18 and skewed priming of helper T lymphocytes (Th1/Th17) by SCZ astrocytes. This phenotype was rescued by specific inhibition of NLRP3 activation, demonstrating its dependence on the NLRP3 inflammasome. Taken together, SCZ iPSC-astrocytes display unique, NLRP3-dependent inflammatory characteristics that are manifested via various cellular functions, as well as via dysregulated innate and adaptive immune responses.

• Baune, B.T.; Fromme, S.E.; Aberg, M.; Adli, M.; Afantitis, A. & Akkouh, Ibrahim Ahmed [Show all 75 contributors for this article] (2024). A stratified treatment algorithm in psychiatry: a program on stratified pharmacogenomics in severe mental illness (Psych-STRATA): concept, objectives and methodologies of a multidisciplinary project funded by Horizon Europe. European Archives of Psychiatry and Clinical Neuroscience. ISSN 0940-1334. doi: 10.1007/s00406-024-01944-3. Full text in Research Archive Show summary

  Schizophrenia (SCZ), bipolar (BD) and major depression disorder (MDD) are severe psychiatric disorders that are challenging to treat, often leading to treatment resistance (TR). It is crucial to develop effective methods to identify and treat patients at risk of TR at an early stage in a personalized manner, considering their biological basis, their clinical and psychosocial characteristics. Effective translation of theoretical knowledge into clinical practice is essential for achieving this goal. The Psych-STRATA consortium addresses this research gap through a seven-step approach. First, transdiagnostic biosignatures of SCZ, BD and MDD are identified by GWAS and multi-modal omics signatures associated with treatment outcome and TR (steps 1 and 2). In a next step (step 3), a randomized controlled intervention study is conducted to test the efficacy and safety of an early intensified pharmacological treatment. Following this RCT, a combined clinical and omics-based algorithm will be developed to estimate the risk for TR. This algorithm-based tool will be designed for early detection and management of TR (step 4). This algorithm will then be implemented into a framework of shared treatment decision-making with a novel mental health board (step 5). The final focus of the project is based on patient empowerment, dissemination and education (step 6) as well as the development of a software for fast, effective and individualized treatment decisions (step 7). The project has the potential to change the current trial and error treatment approach towards an evidence-based individualized treatment setting that takes TR risk into account at an early stage.

• Holmgren, Asbjørn; Akkouh, Ibrahim Ahmed; O'Connell, Kevin Sean; Osete, Jordi Requena; Bjørnstad, Pål Marius & Djurovic, Srdjan [Show all 7 contributors for this article] (2024). Bipolar patients display stoichiometric imbalance of gene expression in post-mortem brain samples. Molecular Psychiatry. ISSN 1359-4184. 29. doi: 10.1038/s41380-023-02398-0. Full text in Research Archive Show summary

  Bipolar disorder is a severe neuro-psychiatric condition where genome-wide association and sequencing studies have pointed to dysregulated gene expression as likely to be causal. We observed strong correlation in expression between GWAS-associated genes and hypothesised that healthy function depends on balance in the relative expression levels of the associated genes and that patients display stoichiometric imbalance. We developed a method for quantifying stoichiometric imbalance and used this to predict each sample’s diagnosis probability in four cortical brain RNAseq datasets. The percentage of phenotypic variance on the liability-scale explained by these probabilities ranged from 10.0 to 17.4% (AUC: 69.4–76.4%) which is a multiple of the classification performance achieved using absolute expression levels or GWAS-based polygenic risk scores. Most patients display stoichiometric imbalance in three to ten genes, suggesting that dysregulation of only a small fraction of associated genes can trigger the disorder, with the identity of these genes varying between individuals.

• Mäki-Marttunen, Tuomo; Blackwell, Kim T.; Akkouh, Ibrahim Ahmed; Shadrin, Alexey; Valstad, Mathias & Elvsåshagen, Torbjørn [Show all 10 contributors for this article] (2024). Genetic mechanisms for impaired synaptic plasticity in schizophrenia revealed by computational modeling. Proceedings of the National Academy of Sciences of the United States of America (PNAS). ISSN 0027-8424. 121(34). doi: 10.1073/pnas.2312511121. Full text in Research Archive Show summary

  Schizophrenia phenotypes are suggestive of impaired cortical plasticity in the disease, but the mechanisms of these deficits are unknown. Genomic association studies have implicated a large number of genes that regulate neuromodulation and plasticity, indicating that the plasticity deficits have a genetic origin. Here, we used biochemically detailed computational modeling of postsynaptic plasticity to investigate how schizophrenia-associated genes regulate long-term potentiation (LTP) and depression (LTD). We combined our model with data from postmortem RNA expression studies (CommonMind gene-expression datasets) to assess the consequences of altered expression of plasticity-regulating genes for the amplitude of LTP and LTD. Our results show that the expression alterations observed post mortem, especially those in the anterior cingulate cortex, lead to impaired protein kinase A (PKA)-pathway-mediated LTP in synapses containing GluR1 receptors. We validated these findings using a genotyped electroencephalogram (EEG) dataset where polygenic risk scores for synaptic and ion channel-encoding genes as well as modulation of visual evoked potentials were determined for 286 healthy controls. Our results provide a possible genetic mechanism for plasticity impairments in schizophrenia, which can lead to improved understanding and, ultimately, treatment of the disorder.

• Lenk, Hasan Cagin; Koch, Elise Mirjam; O'Connell, Kevin Sean; Smith, Robert Løvsletten; Akkouh, Ibrahim Ahmed & Djurovic, Srdjan [Show all 8 contributors for this article] (2024). Genome-wide association analysis of treatment resistant schizophrenia for variant discovery and polygenic assessment. Human Genomics. ISSN 1473-9542. 18(1). doi: 10.1186/s40246-024-00673-x. Full text in Research Archive Show summary

  Background Treatment resistant schizophrenia (TRS) is broadly defined as inadequate response to adequate treatment and is associated with a substantial increase in disease burden. Clozapine is the only approved treatment for TRS, showing superior clinical effect on overall symptomatology compared to other drugs, and is the prototype of atypical antipsychotics. Risperidone, another atypical antipsychotic with a more distinctive dopamine 2 antagonism, is commonly used in treatment of schizophrenia. Here, we conducted a genome-wide association study on patients treated with clozapine (TRS) vs. risperidone (non-TRS) and investigated whether single variants and/or polygenic risk score for schizophrenia are associated with TRS status. We hypothesized that patients who are treated with clozapine and risperidone might exhibit distinct neurobiological phenotypes that match pharmacological profiles of these drugs and can be explained by genetic differences. The study population (n = 1286) was recruited from a routine therapeutic drug monitoring (TDM) service between 2005 and 2022. History of a detectable serum concentration of clozapine and risperidone (without TDM history of clozapine) defined the TRS (n = 478) and non-TRS (n = 808) group, respectively. Results We identified a suggestive association between TRS and a common variant within the LINC00523 gene with a significance just below the genome-wide threshold (rs79229764 C > T, OR = 4.89; p = 1.8 × 10−7). Polygenic risk score for schizophrenia was significantly associated with TRS (OR = 1.4, p = 2.1 × 10−6). In a large post-mortem brain sample from schizophrenia donors (n = 214; CommonMind Consortium), gene expression analysis indicated that the rs79229764 variant allele might be involved in the regulation of GPR88 and PUDP, which plays a role in striatal neurotransmission and intellectual disability, respectively. Conclusions We report a suggestive genetic association at the rs79229764 locus with TRS and show that genetic liability for schizophrenia is positively associated with TRS. These results suggest a candidate locus for future follow-up studies to elucidate the molecular underpinnings of TRS. Our findings further demonstrate the value of both single variant and polygenic association analyses for TRS prediction.

• Lekva, Tove; Michelsen, Annika Elisabet; Roland, Marie Cecilie; Norwitz, Errol R.; Estensen, Mette-Elise & Olstad, Ole Kristoffer [Show all 11 contributors for this article] (2023). Increased ferroptosis in leukocytes from preeclamptic women involving the long non-coding taurine upregulated gene 1 (TUG1). Journal of Internal Medicine. ISSN 0954-6820. 295(2), p. 181–195. doi: 10.1111/joim.13732. Full text in Research Archive Show summary

  Abstract Background Ferroptosis plays a key role in placental development and physiology, and abnormal ferroptosis has been implicated in trophoblast injury leading to preeclampsia (PE). We hypothesize that leukocytes isolated from PE exhibit increased ferroptosis and that extracellular vesicles contain long non‐coding (lnc) RNA/mRNAs that modulate oxidative stress and iron toxicity in vascular endothelial cells. Methods We measured the expression of key regulators of ferroptosis in leukocytes and extracellular vesicles as well as circulating biomarkers of iron homeostasis and oxidative stress in plasma from women with/without PE at different timepoints during pregnancy. For markers that were dysregulated, we assessed their temporal correlation with established markers of disease activity and marker of endothelial activation. For markers dysregulated in early pregnancy, we assessed their ability to predict the development of PE. Results We found decreased lncRNA/mRNAs in leukocytes, but not extracellular vesicles, in PE that may modulate oxidative stress and iron toxicity. This decrease in anti‐ferroptotic markers does not appear to be related to maternal disease activity or plasma oxidative stress status but rather to attenuated anti‐inflammatory expression in these cells. Circulating ferritin was elevated in PE, supporting the hypothesis that PE represents a disbalance in iron homeostasis. Low lncRNA taurine upregulated gene 1 RNA levels in leukocytes at 22–24 weeks were strongly associated with the development of PE. Conclusions Our findings suggest that maternal leukocytes in PE show decreased anti‐ferroptotic activity that correlates with anti‐inflammatory expression. Moreover, some of these changes in ferroptotic activity appear to precede the development of PE.

• Aas, Monica; Andreassen, Ole; Gjerstad, Johannes; Rødevand, Linn; Hjell, Gabriela & Johansen, Ingrid Torp [Show all 12 contributors for this article] (2023). Expression of ANK3 moderates the association between childhood trauma and affective traits in severe mental disorders. Scientific Reports. 13:13845, p. 1–9. doi: 10.1038/s41598-023-40310-6. Full text in Research Archive Show summary

  Exposure to early life trauma increases the risk of psychopathology later in life. Here we investigated if ANK3 mRNA levels influence the relationship between childhood trauma experiences and clinical characteristics in mental disorders. A sample of 174 patients with bipolar disorder and 291 patients with schizophrenia spectrum disorder were included. Patients were diagnosed using the Structured Clinical Interview for DSM-IV, and childhood trauma was assessed using the childhood trauma questionnaire. Age at illness onset and number of psychotic and affective episodes were assessed from interview and medical records. Current depressive symptoms were measured using the calgary depression scale for schizophrenia and the inventory for depressive symptomatology. ANK3 expression was analyzed in whole blood using the Illumina HumanHT-12 v4 Expression BeadChip. Analyses were carried out with the Process adjusted for confounders. Within the total sample, patients with both high ANK3 expression and with the most severe childhood sexual abuse had more manic/hypomanic episodes and an earlier age at onset of the first episode. ANK3 mRNA levels also moderated the relationship between emotional neglect and manic/hypomanic episodes. Our results suggest that ANK3 expression levels moderate the association between specific types of childhood trauma and affective traits in mental disorders.

• Akkouh, Ibrahim Ahmed; Ueland, Thor; Szabo, Attila; Hughes, Timothy; Smeland, Olav Bjerkehagen & Andreassen, Ole [Show all 8 contributors for this article] (2023). Longitudinal Transcriptomic Analysis of Human Cortical Spheroids Identifies Axonal Dysregulation in the Prenatal Brain as a Mediator of Genetic Risk for Schizophrenia. Biological Psychiatry. ISSN 0006-3223. 0(7), p. 1–12. doi: 10.1016/j.biopsych.2023.08.017. Full text in Research Archive Show summary

  Background Schizophrenia (SCZ) has a known neurodevelopmental etiology, but limited access to human prenatal brain tissue hampers the investigation of basic disease mechanisms in early brain development. Here, we elucidate the molecular mechanisms contributing to SCZ risk in a disease-relevant model of the prenatal human brain. Methods We generated induced pluripotent stem cell–derived organoids, termed human cortical spheroids (hCSs), from a large, genetically stratified sample of 14 SCZ cases and 14 age- and sex-matched controls. The hCSs were differentiated for 150 days, and comprehensive molecular characterization across 4 time points was carried out. Results The transcriptional and cellular architecture of hCSs closely resembled that of fetal brain tissue at 10 to 24 postconception weeks, showing strongest spatial overlap with frontal regions of the cerebral cortex. A total of 3520 genes were differentially modulated between SCZ and control hCSs across organoid maturation, displaying a significant contribution of genetic loading, an overrepresentation of risk genes for autism spectrum disorder and SCZ, and the strongest enrichment for axonal processes in all hCS stages. The two axon guidance genes SEMA7A and SEMA5A, the first a promoter of synaptic functions and the second a repressor, were downregulated and upregulated, respectively, in SCZ hCSs. This expression pattern was confirmed at the protein level and replicated in a large postmortem sample. Conclusions Applying a disease-relevant model of the developing fetal brain, we identified consistent dysregulation of axonal genes as an early risk factor for SCZ, providing novel insights into the effects of genetic predisposition on the neurodevelopmental origins of the disorder.

• Osete, Jordi Requena; Akkouh, Ibrahim Ahmed; Ievglevskyi, Oleksandr; Vandenberghe, Matthieu; Assis, Denis Reis de & Ueland, Thor [Show all 14 contributors for this article] (2023). Characterization of lithium (Li) treated human cortical spheroids (hCS). Molecular Psychiatry. ISSN 1359-4184. 28(7). doi: 10.1038/s41380-023-02300-y. Full text in Research Archive
• O'Connell, Kevin Sean; Koch, Elise; Lenk, Hasan Cagin; Akkouh, Ibrahim Ahmed; Hindley, Guy Frederick Lanyon & Jaholkowski, Piotr Pawel [Show all 16 contributors for this article] (2023). Polygenic overlap with body-mass index improves prediction of treatment-resistant schizophrenia. Psychiatry Research. ISSN 0165-1781. 325. doi: 10.1016/j.psychres.2023.115217. Full text in Research Archive Show summary

  Treatment resistant schizophrenia (TRS) is characterized by repeated treatment failure with antipsychotics. A recent genome-wide association study (GWAS) of TRS showed a polygenic architecture, but no significant loci were identified. Clozapine is shown to be the superior drug in terms of clinical effect in TRS; at the same time it has a serious side effect profile, including weight gain. Here, we sought to increase power for genetic discovery and improve polygenic prediction of TRS, by leveraging genetic overlap with Body Mass Index (BMI). We analysed GWAS summary statistics for TRS and BMI applying the conditional false discovery rate (cFDR) framework. We observed cross-trait polygenic enrichment for TRS conditioned on associations with BMI. Leveraging this cross-trait enrichment, we identified 2 novel loci for TRS at cFDR <0.01, suggesting a role of MAP2K1 and ZDBF2. Further, polygenic prediction based on the cFDR analysis explained more variance in TRS when compared to the standard TRS GWAS. These findings highlight putative molecular pathways which may distinguish TRS patients from treatment responsive patients. Moreover, these findings confirm that shared genetic mechanisms influence both TRS and BMI and provide new insights into the biological underpinnings of metabolic dysfunction and antipsychotic treatment.

• Osete, Jordi Requena; Akkouh, Ibrahim Ahmed; Ievglevskyi, Oleksandr; Vandenberghe, Matthieu; Assis, Denis Reis de & Ueland, Thor [Show all 14 contributors for this article] (2023). Transcriptional and functional effects of lithium in bipolar disorder iPSC-derived cortical spheroids. Molecular Psychiatry. ISSN 1359-4184. 28, p. 3033–3043. doi: 10.1038/s41380-023-01944-0. Full text in Research Archive Show summary

  Lithium (Li) is recommended for long-term treatment of bipolar disorder (BD). However, its mechanism of action is still poorly understood. Induced pluripotent stem cell (iPSC)-derived brain organoids have emerged as a powerful tool for modeling BD-related disease mechanisms. We studied the effects of 1 mM Li treatment for 1 month in iPSC-derived human cortical spheroids (hCS) from 10 healthy controls (CTRL) and 11 BD patients (6 Li-responders, Li-R, and 5 Li non-treated, Li-N). At day 180 of differentiation, BD hCS showed smaller size, reduced proportion of neurons, decreased neuronal excitability and reduced neural network activity compared to CTRL hCS. Li rescued excitability of BD hCS neurons by exerting an opposite effect in the two diagnostic groups, increasing excitability in BD hCS and decreasing it in CTRL hCS. We identified 132 Li-associated differentially expressed genes (DEGs), which were overrepresented in sodium ion homeostasis and kidney-related pathways. Moreover, Li regulated secretion of pro-inflammatory cytokines and increased mitochondrial reserve capacity in BD hCS. Through long-term Li treatment of a human 3D brain model, this study partly elucidates the functional and transcriptional mechanisms underlying the clinical effects of Li, such as rescue of neuronal excitability and neuroprotection. Our results also underscore the substantial influence of treatment duration in Li studies. Lastly, this study illustrates the potential of patient iPSC-derived 3D brain models for precision medicine in psychiatry.

• Wang, Shan; Rhijn, Jon-Ruben van; Akkouh, Ibrahim Ahmed; Kogo, Naoki; Maas, Nadine & Bleeck, Anna [Show all 15 contributors for this article] (2022). Loss-of-function variants in the schizophrenia risk gene SETD1A alter neuronal network activity in human neurons through the cAMP/PKA pathway. Cell reports. 39(5). doi: 10.1016/j.celrep.2022.110790. Full text in Research Archive Show summary

  Heterozygous loss-of-function (LoF) mutations in SETD1A, which encodes a subunit of histone H3 lysine 4 methyltransferase, cause a neurodevelopmental syndrome and increase the risk for schizophrenia. Using CRISPR-Cas9, we generate excitatory/inhibitory neuronal networks from human induced pluripotent stem cells with a SETD1A heterozygous LoF mutation (SETD1A+/-). Our data show that SETD1A haploinsufficiency results in morphologically increased dendritic complexity and functionally increased bursting activity. This network phenotype is primarily driven by SETD1A haploinsufficiency in glutamatergic neurons. In accordance with the functional changes, transcriptomic profiling reveals perturbations in gene sets associated with glutamatergic synaptic function. At the molecular level, we identify specific changes in the cyclic AMP (cAMP)/ Protein Kinase A pathway pointing toward a hyperactive cAMP pathway in SETD1A+/- neurons. Finally, by pharmacologically targeting the cAMP pathway, we are able to rescue the network deficits in SETD1A+/- cultures. Our results demonstrate a link between SETD1A and the cAMP-dependent pathway in human neurons.

• Jensen, Søren Beck; Sheikh, Mashhood Ahmed; Akkouh, Ibrahim Ahmed; Szabo, Attila; O'Connell, Kevin Sean & Lekva, Tove [Show all 23 contributors for this article] (2022). Elevated Systemic Levels of Markers Reflecting Intestinal Barrier Dysfunction and Inflammasome Activation Are Correlated in Severe Mental Illness. Schizophrenia Bulletin. ISSN 0586-7614. 49(3), p. 635–645. doi: 10.1093/schbul/sbac191. Full text in Research Archive Show summary

  Abstract Background and Hypothesis Gut microbiota alterations have been reported in severe mental illness (SMI) but fewer studies have probed for signs of gut barrier disruption and inflammation. We hypothesized that gut leakage of microbial products due to intestinal inflammation could contribute to systemic inflammasome activation in SMI. Study Design We measured plasma levels of the chemokine CCL25 and soluble mucosal vascular addressin cell adhesion molecule-1 (sMAdCAM-1) as markers of T cell homing, adhesion and inflammation in the gut, lipopolysaccharide binding protein (LBP) and intestinal fatty acid binding protein (I-FABP) as markers of bacterial translocation and gut barrier dysfunction, in a large SMI cohort (n = 567) including schizophrenia (SCZ, n = 389) and affective disorder (AFF, n = 178), relative to healthy controls (HC, n = 418). We assessed associations with plasma IL-18 and IL-18BPa and leukocyte mRNA expression of NLRP3 and NLRC4 as markers of inflammasome activation. Study Results Our main findings were: (1) higher levels of sMAdCAM-1 (P = .002), I-FABP (P = 7.6E−11), CCL25 (P = 9.6E−05) and LBP (P = 2.6E−04) in SMI compared to HC in age, sex, BMI, CRP and freezer storage time adjusted analysis; (2) the highest levels of sMAdCAM-1 and CCL25 (both P = 2.6E−04) were observed in SCZ and I-FABP (P = 2.5E−10) and LBP (3) in AFF; and (3), I-FABP correlated with IL-18BPa levels and LBP correlated with NLRC4. Conclusions Our findings support that intestinal barrier inflammation and dysfunction in SMI could contribute to systemic inflammation through inflammasome activation.

• Sheikh, Mashhood Ahmed; O'Connell, Kevin Sean; Lekva, Tove; Szabo, Attila; Akkouh, Ibrahim Ahmed & Osete, Jordi Requena [Show all 31 contributors for this article] (2022). Systemic cell adhesion molecules in severe mental illness: Potential role of intercellular CAM-1 in linking peripheral and neuroinflammation. Biological Psychiatry. ISSN 0006-3223. 93, p. 187–196. doi: 10.1016/j.biopsych.2022.06.029. Full text in Research Archive Show summary

  Background Cell adhesion molecules (CAMs) orchestrate leukocyte trafficking and could link peripheral and neuroinflammation in patients with severe mental illness (SMI), by promoting inflammatory and immune-mediated responses and mediating signals across blood-brain barrier. We hypothesized that CAMs would be dysregulated in SMI and evaluated plasma levels of different vascular and neural CAMs. Dysregulated CAMs in plasma were further evaluated in vivo in leukocytes and brain tissue and in vitro in induced pluripotent stem cells. Methods We compared plasma soluble levels of different vascular (VCAM-1, ICAM-1, P-SEL) and neural (JAM-A, NCAD) CAMs in circulating leukocytes in a large SMI sample of schizophrenia (SCZ) spectrum disorder (n = 895) and affective disorder (n = 737) and healthy control participants (n = 1070) controlling for age, sex, body mass index, C-reactive protein, and freezer storage time. We also evaluated messenger RNA expression of ICAM1 and related genes encoding ICAM-1 receptors in leukocytes using microarray (n = 842) and in available RNA sequencing data from the CommonMind Consortium (CMC) in postmortem samples from the dorsolateral prefrontal cortex (n = 474). The regulation of soluble ICAM-1 in induced pluripotent stem cell–derived neurons and astrocytes was assessed in patients with SCZ and healthy control participants (n = 8 of each). Results Our major findings were 1) increased soluble ICAM-1 in patients with SMI compared with healthy control participants; 2) increased ITGB2 messenger RNA, encoding the beta chain of the ICAM-1 receptor, in circulating leukocytes from patients with SMI and increased prefrontal cortex messenger RNA expression of ICAM1 in SCZ; and 3) enhanced soluble ICAM-1 release in induced pluripotent stem cell–derived neurons from patients with SCZ. Conclusions Our results support a systemic and cerebral dysregulation of soluble ICAM-1 expression in SMI and especially in patients with SCZ.

• Szabo, Attila; Akkouh, Ibrahim A.; Vandenberghe, Matthieu; Osete, Jordi Requena; Hughes, Timothy & Heine, Vivi [Show all 10 contributors for this article] (2021). A human iPSC-astroglia neurodevelopmental model reveals divergent transcriptomic patterns in schizophrenia. Translational Psychiatry. 11(1). doi: 10.1038/s41398-021-01681-4. Full text in Research Archive Show summary

  While neurodevelopmental abnormalities have been associated with schizophrenia (SCZ), the role of astroglia in disease pathophysiology remains poorly understood. In the present study, we used a human induced pluripotent stem cell (iPSC)-derived astrocyte model to investigate the temporal patterns of astroglia differentiation during developmental stages critical for SCZ using RNA sequencing. The model generated astrocyte-specific gene expression patterns during differentiation that corresponded well to astroglia-specific expression signatures of in vivo cortical fetal development. Using this model we identified SCZ-specific expression dynamics, and found that SCZ-associated differentially expressed genes were significantly enriched in the medial prefrontal cortex, striatum, and temporal lobe, targeting VWA5A and ADAMTS19. In addition, SCZ astrocytes displayed alterations in calcium signaling, and significantly decreased glutamate uptake and metalloproteinase activity relative to controls. These results implicate novel transcriptional dynamics in astrocyte differentiation in SCZ together with functional changes that are potentially important biological components of SCZ pathology.

• Akkouh, Ibrahim; Hribkova, Hana; Grabiec, Marta; Budinska, Eva; Szabo, Attila & Kasparek, Tomas [Show all 9 contributors for this article] (2021). Derivation and Molecular Characterization of a Morphological Subpopulation of Human iPSC Astrocytes Reveal a Potential Role in Schizophrenia and Clozapine Response. Schizophrenia Bulletin. ISSN 0586-7614. doi: 10.1093/schbul/sbab092. Full text in Research Archive Show summary

  Astrocytes are the most abundant cell type in the human brain and are important regulators of several critical cellular functions, including synaptic transmission. Although astrocytes are known to play a central role in the etiology and pathophysiology of schizophrenia, little is known about their potential involvement in clinical response to the antipsychotic clozapine. Moreover, astrocytes display a remarkable degree of morphological diversity, but the potential contribution of astrocytic subtypes to disease biology and drug response has received little attention. Here, we used state-of-the-art human induced pluripotent stem cell (hiPSC) technology to derive a morphological subtype of astrocytes from healthy individuals and individuals with schizophrenia, including responders and nonresponders to clozapine. Using functional assays and transcriptional profiling, we identified a distinct gene expression signature highly specific to schizophrenia as shown by disease association analysis of more than 10 000 diseases. We further found reduced levels of both glutamate and the NMDA receptor coagonist D-serine in subtype astrocytes derived from schizophrenia patients, and that exposure to clozapine only rescued this deficiency in cells from clozapine responders, providing further evidence that D-serine in particular, and NMDA receptor-mediated glutamatergic neurotransmission in general, could play an important role in disease pathophysiology and clozapine action. Our study represents a first attempt to explore the potential contribution of astrocyte diversity to schizophrenia pathophysiology using a human cellular model. Our findings suggest that specialized subtypes of astrocytes could be important modulators of disease pathophysiology and clinical drug response, and warrant further investigations.

• Assis, Denis Reis de; Szabo, Attila; Osete, Jordi Requena; Puppo, Francesca; O'Connell, Kevin S. & Akkouh, Ibrahim [Show all 10 contributors for this article] (2021). Using iPSC Models to Understand the Role of Estrogen in Neuron–Glia Interactions in Schizophrenia and Bipolar Disorder. Cells. 10(2). doi: 10.3390/cells10020209. Full text in Research Archive Show summary

  Schizophrenia (SCZ) and bipolar disorder (BIP) are severe mental disorders with a considerable disease burden worldwide due to early age of onset, chronicity, and lack of efficient treatments or prevention strategies. Whilst our current knowledge is that SCZ and BIP are highly heritable and share common pathophysiological mechanisms associated with cellular signaling, neurotransmission, energy metabolism, and neuroinflammation, the development of novel therapies has been hampered by the unavailability of appropriate models to identify novel targetable pathomechanisms. Recent data suggest that neuron–glia interactions are disturbed in SCZ and BIP, and are modulated by estrogen (E2). However, most of the knowledge we have so far on the neuromodulatory effects of E2 came from studies on animal models and human cell lines, and may not accurately reflect many processes occurring exclusively in the human brain. Thus, here we highlight the advantages of using induced pluripotent stem cell (iPSC) models to revisit studies of mechanisms underlying beneficial effects of E2 in human brain cells. A better understanding of these mechanisms opens the opportunity to identify putative targets of novel therapeutic agents for SCZ and BIP. In this review, we first summarize the literature on the molecular mechanisms involved in SCZ and BIP pathology and the beneficial effects of E2 on neuron–glia interactions. Then, we briefly present the most recent developments in the iPSC field, emphasizing the potential of using patient-derived iPSCs as more relevant models to study the effects of E2 on neuron–glia interactions.

• Osete, Jordi Requena; Akkouh, Ibrahim; Assis, Denis Reis de; Szabo, Attila; Frei, Evgeniia & Hughes, Timothy [Show all 10 contributors for this article] (2021). Lithium increases mitochondrial respiration in iPSC-derived neural precursor cells from lithium responders. Molecular Psychiatry. ISSN 1359-4184. doi: 10.1038/s41380-021-01164-4. Full text in Research Archive Show summary

  Lithium (Li), valproate (VPA) and lamotrigine (LTG) are commonly used to treat bipolar disorder (BD). While their clinical efficacy is well established, the mechanisms of action at the molecular level are still incompletely understood. Here we investigated the molecular effects of Li, LTG and VPA treatment in induced pluripotent stem cell (iPSC)-derived neural precursor cells (NPCs) generated from 3 healthy controls (CTRL), 3 affective disorder Li responsive patients (Li-R) and 3 Li non-treated patients (Li-N) after 6 h and 1 week of exposure. Differential expression (DE) analysis after 6 h of treatment revealed a transcriptional signature that was associated with all three drugs and most significantly enriched for ribosome and oxidative phosphorylation (OXPHOS) pathways. In addition to the shared DE genes, we found that Li exposure was associated with 554 genes uniquely regulated in Li-R NPCs and enriched for spliceosome, OXPHOS and thermogenesis pathways. In-depth analysis of the treatment-associated transcripts uncovered a significant decrease in intron retention rate, suggesting that the beneficial influence of these drugs might partly be related to splicing. We examined the mitochondrial respiratory function of the NPCs by exploring the drugs’ effects on oxygen consumption rate (OCR) and glycolytic rate (ECAR). Li improved OCR levels only in Li-R NPCs by enhancing maximal respiration and reserve capacity, while VPA enhanced maximal respiration and reserve capacity in Li-N NPCs. Overall, our findings further support the involvement of mitochondrial functions in the molecular mechanisms of mood stabilizers and suggest novel mechanisms related to the spliceosome, which warrant further investigation.

• Akkouh, Ibrahim; Hughes, Timothy; Steen, Vidar Martin; Glover, Joel; Andreassen, Ole Andreas & Djurovic, Srdjan [Show all 7 contributors for this article] (2021). Transcriptome analysis reveals disparate expression of inflammation-related miRNAs and their gene targets in iPSC-astrocytes from people with schizophrenia. Brain, Behavior, and Immunity. ISSN 0889-1591. 94. doi: 10.1016/j.bbi.2021.01.037. Full text in Research Archive Show summary

  Despite the high heritability of schizophrenia (SCZ), details of its pathophysiology and etiology are still unknown. Recent findings suggest that aberrant inflammatory regulation and microRNAs (miRNAs) are involved. Here we performed a comparative analysis of the global miRNome of human induced pluripotent stem cell (iPSC)-astrocytes, derived from SCZ patients and healthy controls (CTRLs), at baseline and following inflammatory modulation using IL-1β. We identified four differentially expressed miRNAs (miR-337-3p, miR-127-5p, miR-206, miR-1185-1-3p) in SCZ astrocytes that exhibited significantly lower baseline expression relative to CTRLs. Group-specific differential expression (DE) analyses exploring possible distinctions in the modulatory capacity of IL-1β on miRNA expression in SCZ versus CTRL astroglia revealed trends toward altered miRNA expressions. In addition, we analyzed peripheral blood samples from a large cohort of SCZ patients (n = 484) and CTRLs (n = 496) screening for the expression of specific gene targets of the four DE miRNAs that were identified in our baseline astrocyte setup. Three of these genes, LAMTOR4, IL23R, and ERBB3, had a significantly lower expression in the blood of SCZ patients compared to CTRLs after multiple testing correction. We also found nominally significant differences for ERBB2 and IRAK1, which similarly displayed lower expressions in SCZ versus CTRL. Furthermore, we found matching patterns between the expressions of identified miRNAs and their target genes when comparing our in vitro and in vivo results. The current results further our understanding of the pathobiological basis of SCZ.

• Puppo, Francesca; Sadegh, Sanaz; Trujillo, Cleber A.; Thunemann, Martin; Campbell, Evan P. & Vandenberghe, Matthieu [Show all 17 contributors for this article] (2021). All-Optical Electrophysiology in hiPSC-Derived Neurons With Synthetic Voltage Sensors. Frontiers in Cellular Neuroscience. 15. doi: 10.3389/fncel.2021.671549. Full text in Research Archive Show summary

  Voltage imaging and “all-optical electrophysiology” in human induced pluripotent stem cell (hiPSC)-derived neurons have opened unprecedented opportunities for high-throughput phenotyping of activity in neurons possessing unique genetic backgrounds of individual patients. While prior all-optical electrophysiology studies relied on genetically encoded voltage indicators, here, we demonstrate an alternative protocol using a synthetic voltage sensor and genetically encoded optogenetic actuator that generate robust and reproducible results. We demonstrate the functionality of this method by measuring spontaneous and evoked activity in three independent hiPSC-derived neuronal cell lines with distinct genetic backgrounds.

• Krull, Florian; Akkouh, Ibrahim Ahmed; Hughes, Timothy; Bettella, Francesco; Athanasiu, Lavinia & Smeland, Olav Bjerkehagen [Show all 12 contributors for this article] (2021). Dose-dependent transcriptional effects of lithium and adverse effect burden in a psychiatric cohort. Progress in Neuro-psychopharmacology and Biological Psychiatry. ISSN 0278-5846. 112. doi: 10.1016/j.pnpbp.2021.110408. Full text in Research Archive Show summary

  Lithium is the first-line treatment for bipolar disorder (BD), but there is a large variation in response rate and adverse effects. Although the molecular effects of lithium have been studied extensively, the specific mechanisms of action remain unclear. In particular, the molecular changes underlying lithium adverse effects are little known. Multiple linear regression analyses of lithium serum concentrations and global gene expression levels in whole blood were carried out using a large case-control sample (n = 1450). Self-reported adverse effects of lithium were assessed with the “Udvalg for Kliniske Undersøgelser” (UKU) adverse effect rating scale, and regression analysis was used to identify significant associations between lithium-related genes and six of the most common adverse effects. Serum concentrations of lithium were significantly associated with the expression levels of 52 genes (FDR < 0.01), largely replicating previous results. We found 32 up-regulated genes and 20 down-regulated genes in lithium users compared to non-users. The down-regulated gene set was enriched for several processes related to the translational machinery. Two adverse effects were significantly associated (p < 0.01) with three or more lithium-associated genes: tremor (FAM13A-AS1, FAR2, ITGAX, RWDD1, and STARD10) and xerostomia (ANKRD13A, FAR2, RPS8, and RWDD1). The adverse effect association with the largest effect was between CAMK1D expression and nausea/vomiting. These results suggest putative transcriptional mechanisms that may predict lithium adverse effects, and could thus have a large potential for informing clinical practice.

• Akkouh, Ibrahim; Ueland, Thor; Hansson, Lars; Inderhaug, Elin; Hughes, Timothy & Steen, Nils Eiel [Show all 10 contributors for this article] (2020). Decreased IL-1β-induced CCL20 response in human iPSC-astrocytes in schizophrenia: Potential attenuating effects on recruitment of regulatory T cells. Brain, Behavior, and Immunity. ISSN 0889-1591. 87, p. 634–644. doi: 10.1016/j.bbi.2020.02.008. Full text in Research Archive Show summary

  Schizophrenia (SCZ) is a severe mental disorder with a high heritability. Although its pathophysiology is mainly unknown, dysregulated immune activation and inflammation have recently emerged as possible candidates in the underlying mechanisms of SCZ. Previous studies suggest that aberrant inflammasome activation, glia dysregulation, and brain inflammation may be involved in the pathophysiology of the disorder. Here, we studied the effects of inflammatory modulation on human induced pluripotent stem cell (iPSC)-derived astrocytes generated from SCZ patients and healthy controls (CTRL). Inflammasome activation was mimicked by short-term IL-1β exposure, and gene expression were measured with high-coverage RNA-Seq to ensure a global characterization of the transcriptional effects of the treatment. IL-1β exposure modulated several pathways involved in innate immune responses, cell cycle regulation, and metabolism in both SCZ and CTRL astrocytes. Significant differences were found in the expression of HILPDA and CCL20 genes, both of which had reduced up-regulation upon IL-1β treatment in SCZ astrocytes compared to CTRL astrocytes. CCL20 data were further validated and confirmed using qPCR, ELISA, and regulatory T lymphocyte (Treg) migration assays. Additionally, we found significantly decreased mRNA expression of the Treg-specific marker FOXP3 in the blood of a large cohort of SCZ patients (n = 484) compared to CTRL (n = 472). Since CCL20 is a specific chemoattractant for CD4+CD25+CCR6+ Tregs, which are crucially involved in anti-inflammatory responses during brain (auto)inflammation, our results imply a plausible role for an altered astroglia-CCL20-CCR6-Treg axis in SCZ pathophysiology.

• Hughes, Timothy; Hansson, Lars Johan Axel; Akkouh, Ibrahim; Hajdarevic, Riad; Bringsli, Jorunn & Torsvik, Anja [Show all 9 contributors for this article] (2020). Runaway multi-allelic copy number variation at the α-defensin locus in African and Asian populations. Scientific Reports. 10(9101), p. 1–8. doi: 10.1038/s41598-020-65675-w. Full text in Research Archive Show summary

  Alpha defensins are anti-microbial peptides of the innate immune system. The defensin A1 and A3 genes are located in a repeat array of variable copy number (the DEFA1A3 locus) and encode the human neutrophil peptides 1, 2 and 3. The possibility that copy number variation (CNV) may be associated with infection susceptibility and autoimmune pathology motivated the study of DEFA1A3 CNV across populations. We enhanced two existing methods (one qPCR-based and one sequencingbased) to enable copy number estimation that discriminates between DEFA1 and DEFA3 genes. We used these methods to quantify A1/A3 copy number variation in 2504 samples from the 1000 Genomes high-coverage dataset as well as performing FiberFISH assays on selected samples to visualize the haplotypes. These methods produce accurate estimates and show that there are substantial diferences between populations. The African population is a clear outlier with a high frequency of the ancestral pure DEFA1 haplotype, but also harbours exceptionally long haplotypes of 24 copies of both DEFA1 and DEFA3, whilst the East Asian population displays the highest mean level of DEFA3 copy number. Further, our fndings demonstrate that qPCR can be an accurate method for CNV estimation and that defensins substantially extend the known range of copy number variation for a human protein-coding gene.

• Szabo, Attila; Akkouh, Ibrahim; Ueland, Thor; Lagerberg, Trine Vik; Dieset, Ingrid & Bjella, Thomas [Show all 12 contributors for this article] (2020). Cannabis Use Is Associated With Increased Levels of Soluble gp130 in Schizophrenia but Not in Bipolar Disorder. Frontiers in Psychiatry. 11, p. 1–10. doi: 10.3389/fpsyt.2020.00642. Full text in Research Archive Show summary

  The complex effects of plant cannabinoids on human physiology is not yet fully understood, but include a wide spectrum of effects on immune modulation. The immune system and its inflammatory effector pathways are recently emerging as possible causative factors in psychotic disorders. The present study aimed to investigate whether self-administered Cannabis use was associated with changes in circulating immune and neuroendocrine markers in schizophrenia (SCZ) and bipolar disorder (BD) patients. A screening of 13 plasma markers reflecting different inflammatory pathways was performed in SCZ (n = 401) and BD patients (n = 242) after subdividing each group into Cannabis user and non-user subgroups. We found that i) soluble gp130 (sgp130) concentrations were significantly elevated among Cannabis users in the SCZ group (p = 0.002) after multiple testing correction, but not in BD. ii) Nominally significant differences were observed in the levels of IL-1RA (p = 0.0059), YKL40 (p = 0.0069), CatS (p = 0.013), sTNFR1 (p = 0.031), and BDNF (p = 0.020), where these factors exhibited higher plasma levels in Cannabis user SCZ patients than in non-users. iii) These differences in systemic levels were not reflected by altered mRNA expression of genes encoding sgp130, IL-1RA, YKL40, CatS, sTNFR1, and BDNF in whole blood. Our results show that Cannabis self-administration is associated with markedly higher sgp130 levels in SCZ, but not in BD, and that this phenomenon is independent of the modulation of peripheral immune cells. These findings warrant further investigation into the potential IL-6 trans-signaling modulatory, anti-inflammatory, neuroimmune, and biobehavioral-cognitive effects of Cannabis use in SCZ.

• Akkouh, Ibrahim; Skrede, Silje; Holmgren, Asbjørn; Ersland, Kari Merete; Hansson, Lars Johan Axel & Bahrami, Shahram [Show all 10 contributors for this article] (2019). Exploring lithium's transcriptional mechanisms of action in bipolar disorder: a multi-step study. Neuropsychopharmacology. ISSN 0893-133X. p. 1–9. doi: 10.1038/s41386-019-0556-8. Full text in Research Archive Show summary

  Lithium has been the first-line treatment for bipolar disorder (BD) for more than six decades. Although the molecular effects of lithium have been studied extensively and gene expression changes are generally believed to be involved, the specific mechanisms of action that mediate mood regulation are still not known. In this study, a multi-step approach was used to explore the transcriptional changes that may underlie lithium’s therapeutic efficacy. First, we identified genes that are associated both with lithium exposure and with BD, and second, we performed differential expression analysis of these genes in brain tissue samples from BD patients (n = 42) and healthy controls (n = 42). To identify genes that are regulated by lithium exposure, we used high-sensitivity RNA-sequencing of corpus callosum (CC) tissue samples from lithium-treated (n = 8) and non-treated (n = 9) rats. We found that lithium exposure significantly affected 1108 genes (FDR < 0.05), 702 up-regulated and 406 down-regulated. These genes were mostly enriched for molecular functions related to signal transduction, including well-established lithium-related pathways such as mTOR and Wnt signaling. To identify genes with differential expression in BD, we performed expression quantitative trait loci (eQTL) analysis on BD-associated genetic variants from the most recent genome-wide association study (GWAS) using three different gene expression databases. We found 307 unique eQTL genes regulated by BD-associated variants, of which 12 were also significantly modulated by lithium treatment in rats. Two of these showed differential expression in the CC of BD cases: RPS23 was significantly down-regulated (p = 0.0036, fc = 0.80), while GRIN2A showed suggestive evidence of down-regulation in BD (p = 0.056, fc = 0.65). Crucially, GRIN2A was also significantly up-regulated by lithium in the rat brains (p = 2.2e-5, fc = 1.6), which suggests that modulation of GRIN2A expression may be a part of the therapeutic effect of the drug. These results indicate that the recent upsurge in research on this central component of the glutamatergic system, as a target of novel therapeutic agents for affective disorders, is warranted and should be intensified.

• Akkouh, Ibrahim; Ueland, Torill; Andreassen, Ole Andreas; Brattbakk, Hans-Richard; Steen, Vidar Martin & Hughes, Timothy [Show all 7 contributors for this article] (2018). Expression of TCN1 in Blood is Negatively Associated with Verbal Declarative Memory Performance. Scientific Reports. 8:12654, p. 1–11. doi: 10.1038/s41598-018-30898-5. Full text in Research Archive Show summary

  Memory is indispensable for normal cognitive functioning, and the ability to store and retrieve information is central to mental health and disease. The molecular mechanisms underlying complex memory functions are largely unknown, but multiple genome-wide association studies suggest that gene regulation may play a role in memory dysfunction. We performed a global gene expression analysis using a large and balanced case-control sample (n = 754) consisting of healthy controls and schizophrenia and bipolar disorder patients. Our aim was to discover genes that are differentially expressed in relation to memory performance. Gene expression in blood was measured using Illumina HumanHT-12 v4 Expression BeadChip and memory performance was assessed with the updated California Verbal Learning Test (CVLT-II). We found that elevated expression of the vitamin B12-related gene TCN1 (haptocorrin) was significantly associated with poorer memory performance after correcting for multiple testing (β = −1.50, p = 3.75e-08). This finding was validated by quantitative real-time PCR and followed up with additional analyses adjusting for confounding variables. We also attempted to replicate the finding in an independent case-control sample (n = 578). The relationship between TCN1 expression and memory impairment was comparable to that of important determinants of memory function such as age and sex, suggesting that TCN1 could be a clinically relevant marker of memory performance. Thus, we identify TCN1 as a novel genetic finding associated with poor memory function. This finding may have important implications for the diagnosis and treatment of vitamin B12-related conditions.

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