Involvement of the nuclear factor-κB transcriptional complex in prefrontal cortex immune activation in bipolar disorder

Correlations between multimodal neuroimaging and peripheral inflammation in different subtypes and mood states of bipolar disorder: a systematic review

BACKGROUND

Systemic inflammation-immune dysregulation and brain abnormalities are believed to contribute to the pathogenesis of bipolar disorder (BD). However, the connections between peripheral inflammation and the brain, especially the interactions between different BD subtypes and episodes, remain to be elucidated. Therefore, we conducted the present study to provide a comprehensive understanding of the complex association between peripheral inflammation and neuroimaging findings in patients with bipolar spectrum disorders.

METHODS

This systematic review was registered in the International Prospective Register of Systematic Reviews (PROSPERO) database (CRD42023447044) and conducted according to the Population, Intervention, Comparison, Outcomes, and Study Design (PICOS) framework. Online literature databases (PubMed, Web of Science, Scopus, EMBASE, MEDLINE, PsycINFO, and the Cochrane Library) were searched for studies that simultaneously investigated both peripheral inflammation-related factors and magnetic resonance neurography of BD patients up to July 01, 2023. Then, we analysed the correlations between peripheral inflammation and neuroimaging, as well as the variation trends and the shared and specific patterns of these correlations according to different clinical dimensions.

RESULTS

In total, 34 publications ultimately met the inclusion criteria for this systematic review, with 2993 subjects included. Among all patterns of interaction between peripheral inflammation and neuroimaging, the most common pattern was a positive relationship between elevated inflammation levels and decreased neuroimaging measurements. The brain regions most susceptible to inflammatory activation were the anterior cingulate cortex, amygdala, prefrontal cortex, striatum, hippocampus, orbitofrontal cortex, parahippocampal gyrus, postcentral gyrus, and posterior cingulate cortex.

LIMITATIONS

The small sample size, insufficiently explicit categorization of BD subtypes and episodes, and heterogeneity of the research methods limited further implementation of quantitative data synthesis.

CONCLUSIONS

Disturbed interactions between peripheral inflammation and the brain play a critical role in BD, and these interactions exhibit certain commonalities and differences across various clinical dimensions of BD. Our study further confirmed that the fronto-limbic-striatal system may be the central neural substrate in BD patients.

Chronic Treatment with Nigella sativa Oil Exerts Antimanic Properties and Reduces Brain Inflammation in Rats

Nigella sativa (NS) is a native herb consumed habitually in several countries worldwide, possessing manifold therapeutic properties. Among them, anti-inflammatory features have been reported, presumably relating to mechanisms involved in the nuclear factor kappa-B pathway, among others. Given the observed association between neuroimmune factors and mental illness, the primary aim of the present study was to examine the effects of chronic NS use on manic-like behavior in rats, as well as analyze levels of brain inflammatory mediators following NS intake. Using male and female rats, baseline tests were performed; thereafter, rats were fed either regular food (control) or NS-containing food (treatment) for four weeks. Following intervention, behavioral tests were induced (an open field test, sucrose consumption test, three-chamber sociality test, and amphetamine-induced hyperactivity test). Subsequently, brain samples were extracted, and inflammatory mediators were evaluated, including interleukin-6, leukotriene B4, prostaglandin E2, tumor necrosis factor-α, and nuclear phosphorylated-p65. Our findings show NS to result in a marked antimanic-like effect, in tandem with a positive modulation of select inflammatory mediators among male and female rats. The findings reinforce the proposed therapeutic advantages relating to NS ingestion.

Mapping the scientific research on bipolar disorder: A scientometric study of hotspots, bursts, and trends

Bipolar disorder (BD) is a severe psychiatric illness with an increasing prevalence worldwide. Although the pathological mechanism of and pharmacological interventions for BD have been extensively investigated in preclinical and clinical studies, a scientometric analysis of the developmental trends, interdisciplinary frontiers, and research hotspots in this field has not yet been conducted. Therefore, we performed a comprehensive scientometric review of 55,358 published studies on BD over the past two decades (2002-2021) to identify the most frequently used keywords and explore research hotspots and trajectories. The present findings revealed the main distribution, knowledge structure, topic evolution, and emerging topics of BD research. Analysing the risk factors, pathogenesis, key brain regions, comorbid conditions, and treatment strategies for BD contributed to understanding of the aetiology, progression, and treatment of this disorder. These findings provided substantial support for continued research in this area.

Association between polymorphisms of TLR2-1-6 and bipolar disorder in a tunisian population

BACKGROUND

Bipolar disorder (BD) is a complex neuropsychiatric disease that has been strongly linked to immune dysregulation. In particular, an abnormal inflammatory response mediated by toll-like receptor 2 - 1/6 (TLR2-1/6) was described in BD. Nevertheless, genetic factors' contribution is still unknown. Thus, we suggested that functional polymorphisms of TLR2, 1 and 6 could be involved in BD predisposition.

METHODS AND RESULTS

TLR2, 1 and 6 polymorphisms were genotyped by PCR-RFLP in 292 controls and 131 patients from a Tunisian population. Polymorphisms and haplotype associations were explored in BD and binary logistic regression analysis was performed for more powerful associations. In dominant model, we found a significantly higher genotype and minor allele frequencies in healthy females compared to patients for TLR2-196-174Ins/Del (p = 0.04; OR = 0.3, p = 0.04; OR = 0.3, respectively) and for TLR6-S249P only with minor allele (p = 0.03; OR = 0.2). In contrast, TLR2-R677W CT + TT and T allele frequencies were significantly higher in BD (padjusted<10- 4; ORadjusted =46.6, p < 10- 4; OR = 6.3, respectively), specifically in females (CT + TT: 100%). Similarly, TLR1-R80T showed significantly increased GC + CC and C allele frequencies in patients compared to controls (padjusted=0.04; ORadjusted=4, p = 0.009; OR = 4.3, respectively). Moreover, haplotype investigation demonstrated that InsGTCGT (p < 10- 4, OR = 275) and delGCCGT (p = 0.03, OR = 18.5) were significantly overrepresented in BD patients compared to controls.

CONCLUSIONS

We suggest that TLR2-196-174Ins/Del and TLR6-S249P could be protective factors of females against BD. However, TLR2-R677W and TLR1-R80T could be strongly associated with higher risk of BD. Interestingly, TLR2-R677W could be a genetic marker for BD in females. However, further studies with larger groups are needed to confirm these findings.

Reverse cholesterol transport and lipid peroxidation biomarkers in major depression and bipolar disorder: A systematic review and meta-analysis

BACKGROUND

Major depression (MDD) and bipolar disorder (BD) are linked to immune activation, increased oxidative stress, and lower antioxidant defenses.

OBJECTIVES

To systematically review and meta-analyze all data concerning biomarkers of reverse cholesterol transport (RCT), lipid-associated antioxidants, lipid peroxidation products, and autoimmune responses to oxidatively modified lipid epitopes in MDD and BD.

METHODS

Databases including PubMed, Google scholar and SciFinder were searched to identify eligible studies from inception to January 10th, 2023. Guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed.

RESULTS

The current meta-analysis included 176 studies (60 BD and 116 MDD) and examined 34,051 participants, namely 17,094 with affective disorders and 16,957 healthy controls. Patients with MDD and BD showed a) significantly decreased RCT (mainly lowered high-density lipoprotein cholesterol and paraoxonase 1); b) lowered lipid soluble vitamins (including vitamin A, D, and coenzyme Q10); c) increased lipid peroxidation and aldehyde formation, mainly increased malondialdehyde (MDA), 4-hydroxynonenal, peroxides, and 8-isoprostanes; and d) Immunoglobulin (Ig)G responses to oxidized low-density lipoprotein and IgM responses to MDA. The ratio of all lipid peroxidation biomarkers/all lipid-associated antioxidant defenses was significantly increased in MDD (standardized mean difference or SMD = 0.433; 95% confidence intervals (CI): 0.312; 0.554) and BD (SMD = 0.653; CI: 0.501-0.806). This ratio was significantly greater in BD than MDD (p = 0.027).

CONCLUSION

In MDD/BD, lowered RCT, a key antioxidant and anti-inflammatory pathway, may drive increased lipid peroxidation, aldehyde formation, and autoimmune responses to oxidative specific epitopes, which all together cause increased immune-inflammatory responses and neuro-affective toxicity.

Deregulation of NF-κB associated long non-coding RNAs in bipolar disorder

Long non-coding RNAs (lncRNAs) are major genetic factors whose disruption lead to many diseases, including nervous system diseases. Bipolar disorder (BD) is a neuro-psychiatric disease with no definitive diagnosis and incomplete treatment. Regarding the role of NF-κB-associated lncRNAs in the neuro-psychiatric disorders, we examined the expression of three lncRNAs, DICER1-AS1, DILC, and CHAST, in BD patients. To assess lncRNA expression in peripheral blood mononuclear cells (PBMCs) of 50 BD patients and 50 healthy individuals, Real-time PCR was used. Additionally, some clinical characteristics of BD patients were investigated via an analysis of ROC curves and correlations. Based on our results, the expression level of CHAST increased significantly in BD patients in comparison with healthy people, in BD men compared with healthy men, as well as in BD women in comparison with control females (p < 0.05). A similar increase in expression was observed for DILC and DICER1-AS1 lncRNAs in female patients compared with healthy women. Whereas compared to healthy men, DILC was decreased in diseased men. Based on the results of the ROC curve, the area under the curve (AUC) for CHAST lncRNA was 0.83 with a P value of 0.0001. So, the expression level of CHAST lncRNA could play a role in the pathobiology of the BD and be considered a good putative biomarker for individuals with bipolar disorder.

Organoid modeling reveals the tumorigenic potential of the alveolar progenitor cell state

Alveolar type 2 (AT2) cells, the epithelial progenitor cells of the distal lung, are known to be the prominent cell of origin for lung adenocarcinoma. The regulatory programs that control chromatin and gene expression in AT2 cells during the early stages of tumor initiation are not well understood. Here, we dissected the response of AT2 cells to Kras activation and p53 loss (KP) using combined single cell RNA and ATAC sequencing in an established tumor organoid system. Multi-omic analysis showed that KP tumor organoid cells exhibit two major cellular states: one more closely resembling AT2 cells (SPC-high) and another with loss of AT2 identity (hereafter, Hmga2-high). These cell states are characterized by unique transcription factor (TF) networks, with SPC-high states associated with TFs known to regulate AT2 cell fate during development and homeostasis, and distinct TFs associated with the Hmga2-high state. CD44 was identified as a marker of the Hmga2-high state, and was used to separate organoid cultures for functional comparison of these two cell states. Organoid assays and orthotopic transplantation studies indicated that SPC-high cells have higher tumorigenic capacity in the lung microenvironment compared to Hmga2-high cells. These findings highlight the utility of understanding chromatin regulation in the early oncogenic versions of epithelial cells, which may reveal more effective means to intervene the progression of Kras-driven lung cancer.

A gene expression analysis of long non-coding RNAs NKILA and PACER as well as their target genes, NF-κB and cox-2 in bipolar disorder patients

Bipolar disorder (BD) is a severe condition characterized by periods of mania and depression. Despite advances in the neurobiology of bipolar disorder, the exact etiology of the disease remains unclear. There is evidence that Inflammation is associated with bipolar disorder. COX-2 and NF-κB are two critical mediators in the inflammatory pathways. Long non-coding RNAs (lncRNAs) are a new class of non-coding RNAs that play a wide range of roles, especially in developing and maintaining normal brain functions. Two lncRNAs called PACER and NKILA control the expression of COX-2 and NF-κB genes, respectively. In this study, Expression levels of PACER and NKILA lncRNAs, as well as, COX-2 and NF-κB genes were measured in fifty patients with bipolar disorder and 50 healthy individuals by real-time PCR. Expression levels of NKILA and COX2 were considerably reduced in BD patients compared with healthy controls. Such significant downregulation in the expression of NKILA and PACER was only observed in male patients with BD compared with male healthy subjects. Also, according to the results of the ROC curve, the area under curve values for NKILA and COX2 were 0.68 and 0.52 respectively. Consequently, the NKILA gene could be considered a biomarker. By examining the degree of pairwise correlation between genes, all genes had a significant positive correlation with each other. Taken together, these results revealed a function for NKILA and PACER lncRNAs in the pathogenesis of BD.

Altered expression of microglial markers of phagocytosis in schizophrenia

BACKGROUND

Cognitive disturbances in schizophrenia have been linked to a lower density of dendritic spines on pyramidal neurons in the prefrontal cortex (PFC). Complement component C4, which has previously been found at higher levels in schizophrenia, marks synapses for phagocytosis by microglia. Thus, elevated consumption of dendritic spines by microglia mediated through excessive complement activity may play a role in lower spine density in schizophrenia. However, it is unclear if microglia themselves have the molecular capacity for enhanced phagocytosis of spines in schizophrenia.

METHODS

Transcript levels for complement components and microglia-specific phagocytic markers were quantified using quantitative PCR in the PFC of 62 matched pairs of schizophrenia and unaffected comparison subjects and in antipsychotic-exposed monkeys.

RESULTS

Relative to comparison subjects, schizophrenia subjects had higher mRNA levels for C4 (+154 %); C1q (+69 %), which initiates the classical complement pathway that includes C4; and for microglia-specific markers that enable phagocytic activity including TAM receptor tyrosine kinases Axl (+27 %) and MerTK (+27 %) and lysosome-associated glycoprotein CD68 (+27 %) (all p ≤ .042). Transcript levels for microglial phagocytic markers were correlated with C4 mRNA levels in schizophrenia subjects (all r ≥ 0.31, p ≤ .015). We also found further evidence consistent with microglial activation in schizophrenia, including higher mRNA levels for THIK1 (TWIK-related halothane-inhibited potassium channel: +30 %) and lower mRNA levels for the purinergic receptor P2Y12 (-27 %) (all p ≤ .016). Transcript levels were unchanged in antipsychotic-exposed monkeys.

CONCLUSIONS

These results are consistent with the presence of increased complement activity and an elevated molecular capacity of microglia for phagocytosis in the same schizophrenia subjects.

Inflammation-related transcripts define "high" and "low" subgroups of individuals with schizophrenia and bipolar disorder in the midbrain

Dopamine dysregulation in schizophrenia may be associated with midbrain inflammation. Previously, we found elevated levels of pro-inflammatory cytokine mRNAs in the post-mortem midbrain of people with schizophrenia (46%) but not from unaffected controls (0%) using a brain cohort from Sydney, Australia. Here, we measured cytokine mRNAs and proteins in the midbrain in the Stanley Medical Research Institute (SMRI) array cohort (N = 105). We tested if the proportions of individuals with schizophrenia and with high inflammation can be replicated, and if individuals with bipolar disorder with elevated midbrain cytokines can be identified. mRNA levels of 7 immune transcripts from post-mortem midbrain tissue were measured via RT-PCR and two-step recursive clustering analysis was performed using 4 immune transcripts to define "high and low" inflammatory subgroups. The clustering predictors used were identical to our earlier midbrain study, and included: IL1B, IL6, TNF, and SERPINA3 mRNA levels. 46% of schizophrenia cases (16/35 SCZ), 6% of controls (2/33 CTRL), and 29% of bipolar disorder cases (10/35 BPD) were identified as belonging to the high inflammation (HI) subgroups [χ² (2) = 13.54, p < 0.001]. When comparing inflammatory subgroups, all four mRNAs were significantly increased in SCZ-HI and BPD-HI compared to low inflammation controls (CTRL-LI) (p < 0.05). Additionally, protein levels of IL-1β, IL-6, and IL-18 were elevated in SCZ-HI and BPD-HI compared to all other low inflammatory subgroups (all p < 0.05). Surprisingly, TNF-α protein levels were unchanged according to subgroups. In conclusion, we determined that almost half of the individuals with schizophrenia were defined as having high inflammation in the midbrain, replicating our previous findings. Further, we detected close to one-third of those with bipolar disorder to be classified as having high inflammation. Elevations in some pro-inflammatory cytokine mRNAs (IL-1β and IL-6) were also found at the protein level, whereas TNF mRNA and protein levels were not concordant.