Association between TLR2 polymorphisms (- 196-174 Ins/Del, R677W, R753Q, and P631H) and schizophrenia in a Tunisian population

Genetic Predisposition of TLR 1 and TLR 6 Polymorphisms to Schizophrenia Onset and Prediction of Treatment Response

Immunological dysregulation was described as one of the underlying mechanisms of schizophrenia (SCZ). Indeed, altered inflammation triggered by toll-like receptors (TLR) complexes TLR2-1 and TLR2-6 has gained attention in SCZ pathophysiology and treatment response. However, the genetic contribution of TLR1 and TLR6 remains unclear. Therefore, the present study aims to explore the possible association of TLR1 and TLR6 polymorphisms with the genetic predisposition to SCZ and treatment response. The current study included 240 controls and 226 patients genotyped for TLR1 and TLR6 polymorphisms by PCR-RFLP. Genotypic, allelic, and haplotype associations with SCZ and between patient groups based on their response to treatment were analyzed. In the dominant model, TLR1-S602I GG+TG and minor allele were significantly higher in responders compared to controls (p = 0.004; OR = 3.0, p = 0.002; OR = 3.0, respectively). Before treatment, male patients with TLR1-S602I GG+TG and TLR6-S249P TT+CT showed significantly higher SAPS scores (p = 0.01) compared to TT carriers. In response to treatment, TLR1-S602I TT carriers demonstrated a significant decrease in SANS scores (p < 10-4). Moreover, SANS scores were significantly lower in GG+TG carriers compared to TT carriers (p = 0.01), after treatment. Furthermore, TLR6-S249P CC carriers showed a significant decrease in SANS scores (p < 10-4) in opposite to TT+CT carriers (p = 0.6) in response to treatment. Moreover, TLR1-S602I GG+TG revealed a significantly elevated onset age compared to TT in schizophrenic males (p = 0.01). To conclude, our findings suggest that TLR1-S602I and TLR6-S249P could be potential genetic factors for schizophrenia susceptibility and the prediction of treatment response, particularly in males.

Association between genetic variants of TLR2, TLR4, TLR9 and schizophrenia

BACKGROUND AND STUDY AIM

Schizophrenia (SZ) is a multifactorial disorder involving complex interactions between genetic and environmental factors, where immune dysfunction plays a key etiopathogenic role. In order to explore the control of innate immune responses in SZ, we aimed to investigate the potential association between twelve TLR2, TLR4 and TLR9 variants (TLR2: rs4696480T>A, rs3804099T>C, rs3804100T>C; TLR4: rs1927914G>A, rs10759932T>C, rs4986790A>G, rs4986791T>C, rs11536889G>C, rs11536891T>C; TLR9: rs187084A>G, rs352139T>C and rs352140C>T) and SZ susceptibility in a Tunisian population.

PATIENTS AND METHODS

This study included 150 patients and 201 healthy controls with no history of psychiatric illness. Genotyping was done using a TaqMan SNP genotyping assay. We also assessed a haplotype analysis for TLR2, TLR4 and TLR9 variants with SZ using Haploview 4.2 Software.

RESULTS

We found that the AA genotype of the TLR2 rs4696480T>A variant was significantly associated with an increased risk of SZ (46% vs. 31%, P=4.7×10-3, OR=1.87 and 95% CI [1.18-2.97]). The frequency of the TA genotype was significantly higher in the control group than in SZ patients (27% vs. 43%, P=2.1×10-3) and may be associated with protection against SZ (OR=0.49 and 95% CI [0.30-0.80]). Whereas, the TLR9 rs187084-GG genotype was higher in the control group compared to patients (16% vs. 5%, P=1.6×10-3) and would present protection against SZ (OR=0.28, CI=[0.10-0.68]). The ACT haplotype of the TLR2 and the ACC haplotype of the TLR9 gene were identified as a risk haplotypes for SZ (P=0.04, OR=9.30, 95% CI=[1.11-77.71]; P=3×10-4, OR=6.05, 95% CI=[2.29-15.98], respectively).

CONCLUSION

The results indicate that TLR2 and TLR9 genetic diversity may play a role in genetic vulnerability to SZ. However, including more patients and evaluation of TLR2 and TLR9 expression are recommended.

The Emerging Role of Toll-Like Receptor-Mediated Neuroinflammatory Signals in Psychiatric Disorders and Acquired Epilepsy

The new and evolving paradigms of psychiatric disorders pathogenesis are deeply inclined toward chronic inflammation that leads to disturbances in the neuronal networks of patients. A strong association has been established between the inflammation and neurobiology of depression which is mediated by different toll-like receptors (TLRs). TLRs and associated signalling pathways are identified as key immune regulators to stress and infections in neurobiology. They are a special class of transmembrane proteins, which are one of the broadly studied members of the Pattern Recognition Patterns family. This review focuses on summarizing the important findings on the role of TLRs associated with psychotic disorders and acquired epilepsy. This review also shows the promising potential of TLRs in immune response mediated through antidepressant therapies and TLRs polymorphism associated with various psychotic disorders. Moreover, this also sheds light on future directions to further target TLRs as a therapeutic approach for psychiatric disorders.

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.

Counting the Toll of Inflammation on Schizophrenia-A Potential Role for Toll-like Receptors

Toll-like receptors (TLRs) are a family of pattern recognition receptors (PRRs) that are ubiquitously expressed in the human body. They protect the brain and central nervous system from self and foreign antigens/pathogens. The immune response elicited by these receptors culminates in the release of cytokines, chemokines, and interferons causing an inflammatory response, which can be both beneficial and harmful to neurodevelopment. In addition, the detrimental effects of TLR activation have been implicated in multiple neurodegenerative diseases such as Alzheimer's, multiple sclerosis, etc. Many studies also support the theory that cytokine imbalance may be involved in schizophrenia, and a vast amount of literature showcases the deleterious effects of this imbalance on cognitive performance in the human population. In this review, we examine the current literature on TLRs, their potential role in the pathogenesis of schizophrenia, factors affecting TLR activity that contribute towards the risk of schizophrenia, and lastly, the role of TLRs and their impact on cognitive performance in schizophrenia.

Toll-like receptor 10 gene polymorphism and risk of multiple sclerosis among Iraqi patients

Background

Toll-like receptors (TLRs) are a family of 10 pattern recognition receptors (TLR1–TLR10) involved in the regulation of inflammatory and immune responses besides their role in the pathogenesis of autoimmune diseases including multiple sclerosis (MS). TLR10 is the least studied TLR in MS, and data for single nucleotide polymorphisms (SNPs) of the TLR10 gene are limited. Therefore, a case–control study was performed on 85 patients with relapsing–remitting MS and 86 healthy controls (HC) to explore SNPs in the promoter region of TLR10 gene. A 927-bp region was amplified, and Sanger sequencing identified 10 SNPs with a minor allele frequency ≥ 10% (rs200395112 T/A, rs201802754 A/T, rs201228097 T/A, rs113588825 G/A, rs10004195 T/A, rs10034903 C/G, rs10012016 G/A/C, rs10012017 G/T, rs33994884 T/Deletion [Del] and rs28393318 A/G).

Results

Del allele and T/Del genotype of rs33994884, as well as AG genotype of rs28393318, showed significantly lower frequencies in MS patients compared to HC. Allele and genotype frequencies of the 10 SNPs showed no significant differences between MS patients classified according to the Expanded Disability Status Scale. Haplotype analysis revealed that haplotype A-T-A-G-A-G-G-T-A showed a significantly increased frequency in MS patients compared to HC (odds ratio [OR] = 9.70; 95% confidence interval [CI] = 1.28–73.31; corrected probability [pc] = 0.03), while frequency of A-T-A-G-T-C-A-T-G haplotype was significantly decreased (OR = 0.10; 95% CI = 0.01–0.85; pc = 0.05).

Conclusions

The study indicated that two SNPs may influence susceptibility to MS (rs33994884 and rs28393318), but haplotype analysis of TLR10 gene SNPs was more informative.