Overexpression of transmembrane TNFα in brain endothelial cells induces schizophrenia-relevant behaviors

Correlation Between Severity of Schizophrenia with Certain Trace Elements and TNF-α Gene Expression and Its Circulatory Level in the Population of Western India

This cross-sectional study aimed to assess serum trace element (TE) concentrations, TNF-α gene expression, protein levels in schizophrenia (SZ) patients, and their correlation with disease severity measured by Positive and Negative Syndrome Scale (PANSS) scores. Forty SZ cases and 40 healthy controls aged 18-60 were recruited. Forty (n = 40) cases who meet ICD-10 criteria for SZ and 40 (n = 40) healthy individuals (controls) between 18 and 60 years of age were recruited in the study. Sandwich enzyme-linked immunosorbent assay (ELISA) and RT-qPCR (quantitative real-time PCR) were used to estimate pro-inflammatory cytokine TNF-α protein and gene expression. Inductively coupled plasma-optical emission spectroscopy (ICP-OES) and graphite furnace atomic absorption spectroscopy (GFAAS) were used to assess serum levels of trace elements (TEs): Fe, Zn, Cu, Mg, and Se. Compared to healthy controls, cases had significantly higher levels of TNF-α protein, as well as Fe, Cu, and Se (p < 0.05). Cu correlated positively with TNF-α protein level (rho = 0.234; p = 0.048) and gene expression (rho = 0.333; p = 0.041) and with PANSS negative (rho = 0.531), general (rho = 0.643), and total (rho = 0.541) scores. Additionally, Zn negatively correlated with serum Mg (rho =  - 0.426, p < 0.01) and positively with serum Se (rho = 0.343, p < 0.05). In conclusion, elevated Cu levels could potentially contribute to the development of SZ. Elevated Cu levels in cases and their correlation with the TNF-α gene and protein and PANSS score indicate Cu's potential role in exacerbating SZ severity through inflammatory cytokines. This suggests the involvement of metals and cytokines in the pathophysiology of SZ.

Potential role for kynurenine pathway in increased COVID-19 mortality of patients with schizophrenia

Schizophrenia (SCZ) is a common psychiatric disorder that has complex pathological mechanisms. During the coronavirus disease 2019 (COVID-19) epidemic, patients with SCZ had substantially higher rates of infection with SARS-CoV-2, the virus that causes COVID-19, as well as higher COVID-19 mortality relative to patients without mental disorders. Previous studies suggested that COVID-19 and SCZ both involve the kynurenine metabolic pathway. This article reviews the characteristics of kynurenine metabolism in COVID-19 and SCZ, and considers the possibility that disordered kynurenine metabolism may be one cause of increased infection and COVID-19 mortality rates in the patients with SCZ. Several possible molecular mechanisms that could be involved in disease pathology are discussed.

α-linolenic acid mitigates microglia-mediated neuroinflammation of schizophrenia in mice by suppressing the NF-κB/NLRP3 pathway via binding GPR120-β-arrestin 2

BACKGROUND

Schizophrenia (SCZ) is a heterogeneous psychiatric disorder that is poorly treated by current therapies. Emerging evidence indicates that SCZ is closely correlated with a persistent neuroinflammation. α-linolenic acid (ALA) is highly concentrated in the brain and represents a modulator of the immune system by decreasing the inflammatory response in chronic metabolic diseases. This study was first designed to investigate the potential role of dietary ALA on cognitive function and neuroinflammation in mice with SCZ.

METHODS

In vivo, after 2 weeks of modeling, mice were treated with dietary ALA treatment for 6 weeks. In vitro, inflammation model was created using lipopolysaccharide as an inducer in BV2 microglial cells.

RESULTS

Our results demonstrated that ALA alleviated cognitive impairment and enhanced synaptic plasticity in mice with SCZ. Moreover, ALA mitigated systematic and cerebral inflammation through elevating IL-10 and inhibiting IL-1β, IL-6, IL-18 and TNF-α. Furthermore, ALA notably inhibited microglia and pro-inflammatory monocytes, as well as microglial activation andpolarization. Mechanistically, ALA up-regulated the expressions of G protein coupled receptor (GPR) 120 and associated β-inhibitor protein 2 (β-arrestin2), accompanied by observable weakened levels of transforming growth factor-β activated kinase 1 (TAK1), NF-κB p65, cysteine proteinase-1 (caspase-1), pro-caspase-1, associated speck-like protein (ASC) and NLRP3. In vitro, ALA directly restrained the inflammation of microglia by decreasing the levels of pro-inflammatory factors and regulating microglial polarization via GPR120-NF-κB/NLRP3inflammasome signaling pathway, whereas AH7614 definitely eliminated this anti-inflammatory effect of ALA.

CONCLUSION

Dietary ALA ameliorates microglia-mediated neuroinflammation by suppressing the NF-κB/NLRP3 pathway via binding GPR120-β-arrestin2.

TNF receptor 2 knockout mouse had reduced lung cancer growth and schizophrenia-like behavior through a decrease in TrkB-dependent BDNF level

The relationship between schizophrenia (SCZ) and cancer development remains controversial. Based on the disease-gene association platform, it has been revealed that tumor necrosis factor receptor (TNFR) could be an important mediatory factor in both cancer and SCZ development. TNF-α also increases the expression of brain-derived neurotrophic factor (BDNF) and tropomyosin receptor kinase B (TrkB) in the development of SCZ and tumor, but the role of TNFR in mediating the association between the two diseases remains unclear. We studied the vital roles of TNFR2 in the progression of tumor and SCZ-like behavior using A549 lung cancer cell xenografted TNFR2 knockout mice. TNFR2 knockout mice showed significantly decreased tumor size and weight as well as schizophrenia-like behaviors compared to wild-type mice. Consistent with the reduced tumor growth and SCZ-like behaviors, the levels of TrkB and BDNF expression were significantly decreased in the lung tumor tissues and pre-frontal cortex of TNFR2 knockout mice. However, intravenous injection of BDNF (160 μg/kg) to TNFR2 knockout mice for 4 weeks increased tumor growth and SCZ-like behaviors as well as TrkB expression. In in vitro study, significantly decreased cell growth and expression of TrkB and BDNF by siTNFR2 transfection were found in A549 lung cancer cells. However, the addition of BDNF (100 ng/ml) into TNFR2 siRNA transfected A549 lung cancer cells recovered cell growth and the expression of TrkB. These results suggest that TNFR2 could be an important factor in mediating the comorbidity between lung tumor growth and SCZ development through increased TrkB-dependent BDNF levels.

Significance of chitinase-3-like protein 1 in the pathogenesis of inflammatory diseases and cancer

Chitinase-3-like protein 1 (CHI3L1) is a secreted glycoprotein that mediates inflammation, macrophage polarization, apoptosis, and carcinogenesis. The expression of CHI3L1 is strongly upregulated by various inflammatory and immunological diseases, including several cancers, Alzheimer's disease, and atherosclerosis. Several studies have shown that CHI3L1 can be considered as a marker of disease diagnosis, prognosis, disease activity, and severity. In addition, the proinflammatory action of CHI3L1 may be mediated via responses to various proinflammatory cytokines, including tumor necrosis factor-α, interleukin-1β, interleukin-6, and interferon-γ. Therefore, CHI3L1 may contribute to a vast array of inflammatory diseases. However, its pathophysiological and pharmacological roles in the development of inflammatory diseases remain unclear. In this article, we review recent findings regarding the roles of CHI3L1 in the development of inflammatory diseases and suggest therapeutic approaches that target CHI3L1.

Immune-Inflammatory Response And Compensatory Immune-Regulatory Reflex Systems And White Matter Integrity in Schizophrenia

BACKGROUND AND HYPOTHESIS

Low-grade neural and peripheral inflammation are among the proposed pathophysiological mechanisms of schizophrenia. White matter impairment is one of the more consistent findings in schizophrenia but the underlying mechanism remains obscure. Many cerebral white matter components are sensitive to neuroinflammatory conditions that can result in demyelination, altered oligodendrocyte differentiation, and other changes. We tested the hypothesis that altered immune-inflammatory response system (IRS) and compensatory immune-regulatory reflex system (IRS/CIRS) dynamics are associated with reduced white matter integrity in patients with schizophrenia.

STUDY DESIGN

Patients with schizophrenia (SCZ, 70M/50F, age = 40.76 ± 13.10) and healthy controls (HCs, 38M/27F, age = 37.48 ± 12.31) underwent neuroimaging and plasma collection. A panel of cytokines were assessed using enzyme-linked immunosorbent assay. White matter integrity was measured by fractional anisotropy (FA) from diffusion tensor imaging using a 3-T Prisma MRI scanner. The cytokines were used to generate 3 composite scores: IRS, CIRS, and IRS/CIRS ratio.

STUDY RESULTS

The IRS/CIRS ratio in SCZ was significantly higher than that in HCs (P = .009). SCZ had a significantly lower whole-brain white matter average FA (P < .001), and genu of corpus callosum (GCC) was the most affected white matter tract and its FA was significantly associated with IRS/CIRS (r = 0.29, P = .002). FA of GCC was negatively associated with negative symptom scores in SCZ (r = -0.23, P = .016). There was no mediation effect taking FA of GCC as mediator, for that IRS/CIRS was not associated with negative symptom score significantly (P = .217) in SCZ.

CONCLUSIONS

Elevated IRS/CIRS might partly account for the severity of negative symptoms through targeting the integrity of GCC.