Bidirectional two-sample Mendelian randomization study of differential white blood cell counts and schizophrenia.

BACKGROUND: Schizophrenia and white blood cell counts (WBC) are both complex and polygenic traits. Previous evidence suggests that increased WBC are associated with higher all-cause mortality, and other studies have found elevated WBC in first-episode psychosis and chronic schizophrenia. However, these observational findings may be confounded by antipsychotic exposures and their effects on WBC. Mendelian randomization (MR) is a useful method for examining the directions of genetically-predicted relationships between schizophrenia and WBC. METHODS: We performed a two-sample MR using summary statistics from genome-wide association studies (GWAS) conducted by the Psychiatric Genomics Consortium Schizophrenia Workgroup (N = 130,644) and the Blood Cell Consortium (N = 563,946). The MR methods included inverse variance weighted (IVW), MR Egger, weighted median, MR-PRESSO, contamination mixture, and a novel approach called mixture model reciprocal causal inference (MRCI). False discovery rate was employed to correct for multiple testing. RESULTS: Multiple MR methods supported bidirectional genetically-predicted relationships between lymphocyte count and schizophrenia: IVW (b = 0.026; FDR p-value = 0.008), MR Egger (b = 0.026; FDR p-value = 0.008), weighted median (b = 0.013; FDR p-value = 0.049), and MR-PRESSO (b = 0.014; FDR p-value = 0.010) in the forward direction, and IVW (OR = 1.100; FDR p-value = 0.021), MR Egger (OR = 1.231; FDR p-value < 0.001), weighted median (OR = 1.136; FDR p-value = 0.006) and MRCI (OR = 1.260; FDR p-value = 0.026) in the reverse direction. MR Egger (OR = 1.171; FDR p-value < 0.001) and MRCI (OR = 1.154; FDR p-value = 0.026) both suggested genetically-predicted eosinophil count is associated with schizophrenia, but MR Egger (b = 0.060; FDR p-value = 0.010) and contamination mixture (b = -0.013; FDR p-value = 0.045) gave ambiguous results on whether genetically predicted liability to schizophrenia would be associated with eosinophil count. MR Egger (b = 0.044; FDR p-value = 0.010) and MR-PRESSO (b = 0.009; FDR p-value = 0.045) supported genetically predicted liability to schizophrenia is associated with elevated monocyte count, and the opposite direction was also indicated by MR Egger (OR = 1.231; FDR p-value = 0.045). Lastly, unidirectional genetic liability from schizophrenia to neutrophil count were proposed by MR-PRESSO (b = 0.011; FDR p-value = 0.028) and contamination mixture (b = 0.011; FDR p-value = 0.045) method. CONCLUSION: This MR study utilised multiple MR methods to obtain results suggesting bidirectional genetic genetically-predicted relationships for elevated lymphocyte counts and schizophrenia risk. In addition, moderate evidence also showed bidirectional genetically-predicted relationships between schizophrenia and monocyte counts, and unidirectional effect from genetic liability for eosinophil count to schizophrenia and from genetic liability for schizophrenia to neutrophil count. The influence of schizophrenia to eosinophil count is less certain. Our findings support the role of WBC in schizophrenia and concur with the hypothesis of neuroinflammation in schizophrenia.

Characterization of JNJ-2482272 [4-(4-Methyl-2-(4-(Trifluoromethyl)Phenyl)Thiazole-5-yl) Pyrimidine-2-Amine] As a Strong Aryl Hydrocarbon Receptor Activator in Rat and Human.

[4-(4-Methyl-2-(4-(trifluoromethyl)phenyl)thiazole-5-yl)pyrimidine-2-amine] (JNJ-2482272), under investigation as an anti-inflammatory agent, was orally administered to rats once daily at 60 mg/kg for 6 consecutive days. Despite high plasma exposure after single administration (Cmax of 7.1 µM), JNJ-2482272 had plasma concentrations beneath the lower limit of quantification (3 ng/ml) after 6 consecutive days of dosing. To determine if JNJ-2482272 is an autoinducer in rats, plated rat hepatocytes were treated with JNJ-2482272 for 2 days. The major hydroxylated metabolites of JNJ-2482272 were isolated and characterized by mass spectrometry and NMR analyses. Compared with the vehicle-treated cells, a concentration-dependent increase was observed in the formation of phase I- and II-mediated metabolites coinciding with greater expression of cytochrome P450s (P450s) and UDP-glucuronosyltransferases (UGTs) in rat hepatocytes. CYP1A1, CYP1A2, CYP1B1, and UGT1A6 transcripts were predominantly induced, suggesting that JNJ-2482272 is an activator of the aryl hydrocarbon receptor (AhR). In a human AhR reporter assay, JNJ-2482272 demonstrated potent AhR activation with an EC50 value of 0.768 nM, a potency more comparable to the strong AhR activator and toxin 2,3,7,8-tetrachloro-dibenzodioxin than to weaker AhR activators 3-methylcholanthrene, ß-naphthoflavone, and omeprazole. In plated human hepatocytes, JNJ-2482272 induced CYP1A1 gene expression with an EC50 of 20.4 nM and increased CYP1A activity >50-fold from basal levels. In human recombinant P450s, JNJ-2482272 was exclusively metabolized by the CYP1 family of enzymes and most rapidly by CYP1A1. The summation of these in vitro findings bridges the in vivo conclusion that JNJ-2482272 is a strong autoinducer in rats and potentially in humans through potent AhR activation. SIGNIFICANCE STATEMENT: Drugs that induce their own metabolism (autoinducers) can lack sustained exposures for pharmacology and safety assessment hindering their development. JNJ-2482272 is demonstrated herein as a strong aryl hydrocarbon receptor (AhR) activator and CYP1A autoinducer, explaining its near complete loss of exposure after repeat administration in rat, which is likely translatable to human (if progressed further) considering its nanomolar potency comparable to "classical" AhR ligands like 2,3,7,8-tetrachloro-dibenzo-dioxin despite bearing a "nonclassical" drug structure.

Long-term metabolic side effects of second-generation antipsychotics in Chinese patients with schizophrenia: A within-subject approach with modelling of dosage effects.

BACKGROUND: Second-generation antipsychotics (SGAs) are commonly used to treat schizophrenia (SCZ), but SGAs may differ in the severity of side effects. Long-term studies are lacking, and previous observational studies have limitations, such as failure to account for confounding factors and short follow-up durations. AIMS: To compare the long-term anthropometric and metabolic side effects of seven SGAs in a Chinese population, using a within-subject approach to reduce the risk of confounding. METHOD: We collected longitudinal data of SGA prescriptions, concomitant medications, fasting blood glucose (BG), lipid profiles, and BMI in a cohort of 767 patients with SCZ, with follow-up lasting up to 18.7 years (median ∼6.2 years). A total of 192,152 prescription records were retrieved, with 27,723 metabolic measures analysed. Linear mixed models were used to estimate the effects of SGA on BG, lipid profiles and BMI. Besides studying the effects of SGA medications (as binary predictors), we also investigated the effects of SGA dosage on metabolic profiles. RESULTS: Considering SGA medications as binary predictors, clozapine and olanzapine were associated with the most substantial worsening of lipid profiles and BMI. A significant increase in BG was observed with clozapine only. Amisulpride, paliperidone and quetiapine were associated with worsened lipid profiles and increased BMI. Conversely, aripiprazole was associated with significant improvement in lipid profiles but a small increase in BMI. When SGA dosage was considered, the model showed consistent results overall. At the minimum effective dose, clozapine was associated with the most severe metabolic side effects, followed by olanzapine. Risperidone and aripiprazole showed the least metabolic side effects, with aripiprazole being significantly associated with lower lipids. CONCLUSIONS: This study clarified the long-term and dose-dependent effects of different SGAs on anthropometric and metabolic parameters in Chinese SCZ patients. Our findings may inform clinicians and SCZ patients of SGA choices.

Whole-exome sequencing in a Chinese sample provides preliminary evidence for the link between rare/low-frequency immune-related variants and early-onset schizophrenia.

Rare and low-frequency variants contribute to schizophrenia (SCZ), and may influence its age-at-onset (AAO). We examined the association of rare or low-frequency deleterious coding variants in Chinese patients with SCZ. We collected DNA samples in 197 patients with SCZ spectrum disorder and 82 healthy controls (HC), and performed exome sequencing. The AAO variable was ascertained in the majority of SCZ participants for identify the early-onset (EOS, AAO<=18) and adult-onset (AOS, AAO>18) subgroups. We examined the overall association of rare/low-frequency, damaging variants in SCZ versus HC, EOS versus HC, and AOS versus HC at the gene and gene-set levels using Sequence Kernel Association Test. The quantitative rare-variant association test of AAO was conducted. Resampling was used to obtain empirical p-values and to control for family-wise error rate (FWER). In binary-trait association tests, we identified 5 potential candidate risk genes and 10 gene ontology biological processes (GOBP) terms, among which PADI2 reached FWER-adjusted significance. In quantitative rare-variant association tests, we found marginally significant correlations of AAO with alterations in 4 candidate risk genes, and 5 GOBP pathways. Together, the biological and functional profiles of these genes and gene sets supported the involvement of perturbations of neural systems in SCZ, and altered immune functions in EOS.

Negative symptoms in treatment-resistant schizophrenia and its relationship with functioning.

BACKGROUND: Recent operational criteria for treatment-resistant schizophrenia (TRS) recognized positive and negative symptoms. TRS patients may have heterogeneity in negative symptoms, but empirical data were lacking. We aimed to characterize TRS patients based on negative symptoms using cluster analysis, and to examine between-cluster differences in social functioning. METHODS: We administered the Clinical Assessment Interview of Negative symptoms (CAINS), Brief Negative Symptom Scale (BNSS), the Positive and Negative Syndrome Scale (PANSS) and the Social and Occupational Functional Assessment (SOFAS to 126 TRS outpatients. All patients also completed the Temporal Experience of Pleasure Scale (TEPS), the Emotion Expressivity Scale (EES), and the Social Functional Scale (SFS). A two-stage hierarchical cluster analysis was performed with the CAINS, TEPS and EES as clustering variables. We validated the clusters using ANOVAs to compare group differences in the BNSS, PANSS, SOFAS and SFS. RESULTS: Clustering indices supported a 3-cluster solution. Clusters 1 (n = 46) and 3 (n = 16) exhibited higher CAINS scores than Cluster 2 (n = 64), and were negative-symptom TRS subtypes. Cluster 1 reported lower TEPS than Cluster 3; but Cluster 3 reported lower EES than Cluster 1. Upon validation, Clusters 1 and 3 exhibited higher BNSS scores than Cluster 2, but only Cluster 1 exhibited lower SOFAS and higher PANSS general symptoms than Cluster 2. Both Clusters 1 and 3 had higher self-report functioning than Cluster 2. CONCLUSION: We provided evidence for heterogeneity of negative symptoms in TRS. Negative symptoms can characterize TRS patients and predict functional outcome.

Pathway-Specific Polygenic Scores Improve Cross-Ancestry Prediction of Psychosis and Clinical Outcomes.

Psychotic disorders are debilitating conditions with disproportionately high public health burden. Genetic studies indicate high heritability, but current polygenic scores (PGS) account for only a fraction of variance in psychosis risk. PGS often show poor portability across ancestries, performing significantly worse in non-European populations. Pathway-specific PGS (pPGS), which restrict PGS to genomic locations within distinct biological units, could lead to increased mechanistic understanding of pathways that lead to risk and improve cross-ancestry prediction by reducing noise in genetic predictors. This study examined the predictive power of genome-wide PGS and nine pathway-specific pPGS in a unique Chinese-ancestry sample of deeply-phenotyped psychosis patients and non-psychiatric controls. We found strong evidence for the involvement of schizophrenia-associated risk variants within "nervous system development" (p=2.5e-4) and "regulation of neuron differentiation" pathways (p=3.0e-4) in predicting risk for psychosis. We also found the "ion channel complex" pPGS, with weights derived from GWAS of bipolar disorder, to be strongly associated with the number of inpatient psychiatry admissions a patient experiences (p=1.5e-3) and account for a majority of the signal in the overall bipolar PGS. Importantly, although the schizophrenia genome-wide PGS alone explained only 3.7% of the variance in liability to psychosis in this Chinese ancestry sample, the addition of the schizophrenia-weighted pPGS for "nervous system development" and "regulation of neuron differentiation" increased the variance explained to 6.9%, which is on-par with the predictive power of PGS in European ancestry samples. Thus, not only can pPGS provide greater insight into mechanisms underlying genetic risk for disease and clinical outcomes, but may also improve cross-ancestry risk prediction accuracy.

Early-onset schizophrenia is associated with immune-related rare variants in a Chinese sample.

Background: Rare variants are likely to contribute to schizophrenia (SCZ), given the large discrepancy between the heritability estimated from twin and GWAS studies. Furthermore, the nature of the rare-variant contribution to SCZ may vary with the "age-at-onset" (AAO), since early-onset has been suggested as being indicative of neurodevelopment deviance. Objective: To examine the association of rare deleterious coding variants in early- and adult-onset SCZ in a Chinese sample. Method: Exome sequencing was performed on DNA from 197 patients with SCZ spectrum disorder and 82 healthy controls (HC) of Chinese ancestry recruited in Hong Kong. We also gathered AAO information in the majority of SCZ samples. Patients were classified into early-onset (EOS, AAO<18) and adult-onset (AOS, AAO>18). We collapsed the rare variants to improve statistical power and examined the overall association of rare variants in SCZ versus HC, EOS versus HC, and AOS versus HC at the gene and gene-set levels by Sequence Kernel Association Test. The quantitative rare-variant association test of AAO was also conducted. We focused on variants which were predicted to have a medium or high impact on the protein-encoding process as defined by Ensembl. We applied a 100000-time permutation test to obtain empirical p-values, with significance threshold set at p < 1e -3 to control family-wise error rates. Moreover, we compared the burden of targeted rare variants in significant risk genes and gene sets in cases and controls. Results: Based on several binary-trait association tests (i.e., SCZ vs HC, EOS vs HC and AOS vs HC), we identified 7 candidate risk genes and 20 gene ontology biological processes (GOBP) terms, which exhibited higher burdens in SCZ than in controls. Based on quantitative rare-variant association tests, we found that alterations in 5 candidate risk genes and 7 GOBP pathways were significantly correlated with AAO. Based on biological and functional profiles of the candidate risk genes and gene sets, our findings suggested that, in addition to the involvement of perturbations in neural systems in SCZ in general, altered immune responses may be specifically implicated in EOS. Conclusion: Disrupted immune responses may exacerbate abnormal perturbations during neurodevelopment and trigger the early onset of SCZ. We provided evidence of rare variants increasing SCZ risk in the Chinese population.

Novel substituted pyrrolidines are high affinity histamine H3 receptor antagonists.

Pre-clinical characterization of novel substituted pyrrolidines that are high affinity histamine H(3) receptor antagonists is described. These compounds efficiently penetrate the CNS and occupy the histamine H(3) receptor in rat brain following oral administration. One compound, (2S,4R)-1-[2-(4-cyclobutyl-[1,4]diazepane-1-carbonyl)-4-(3-fluoro-phenoxy)-pyrrolidin-1-yl]-ethanone, was extensively profiled and shows promise as a potential clinical candidate.

Pre-clinical characterization of aryloxypyridine amides as histamine H3 receptor antagonists: identification of candidates for clinical development.

The pre-clinical characterization of novel aryloxypyridine amides that are histamine H(3) receptor antagonists is described. These compounds are high affinity histamine H(3) ligands that penetrate the CNS and occupy the histamine H(3) receptor in rat brain. Several compounds were extensively profiled pre-clinically leading to the identification of two compounds suitable for nomination as development candidates.

Lead Optimization of 5-Aryl Benzimidazolone- and Oxindole-Based AMPA Receptor Modulators Selective for TARP γ-8.

Glutamate mediates fast excitatory neurotransmission via ionotropic α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptors. The trafficking and gating properties of AMPA receptors (AMPARs) can be amplified by transmembrane AMPAR regulatory proteins (TARPs), which are often expressed in localized brain regions. Herein, we describe the discovery, lead optimization, and preclinical characterization of 5-arylbenzimidazolone and oxindole-based negative modulators of AMPARs associated with TARP γ-8, the primary TARP found in hippocampus. High-throughput screen lead 4 was optimized for potency and brain penetration to provide benzimidazolone 3, JNJ-55511118.1 Replacement of the benzimidazolone core in 3 with an oxindole mitigated reactive metabolite formation and led to the identification of 18 (GluA1/γ-8 pIC50 = 9.7). Following oral dosing in rats, 18 demonstrated robust target engagement in hippocampus as assessed by ex vivo autoradiography (ED50 = 0.6 mg/kg, plasma EC50 = 9 ng/mL).