Associations of TLR4 gene polymorphisms with the risk of age-related macular degeneration in a Chinese Han population

Toll-Like Receptor 4 Gene Polymorphisms and Susceptibility to Schizophrenia: A Case-Control Study

Schizophrenia is a common psychiatric disorder that exhibits a variety of symptoms. The exact etiology and pathogenesis are still doubtful. However, genetic and environmental factors seem to have a role. Years ago, the role of the immune system was focused on auto-antibodies, cytokines, different types of immune cells and immune genes. The Toll-like receptors (TLR) are a cornerstone of the innate immune system, particularly TLR4. TLR4 primarily recognises gram-negative lipopolysaccharides bacteria. This case-control study, for the first time to our knowledge, examined the role of TLR4 gene polymorphisms in 142 Egyptian schizophrenic patients and 175 healthy controls. Using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), four single nucleotide polymorphisms (SNPs) were investigated in the TLR4 gene rs11536889, rs10759931, rs1927911, and rs1927914. The Positive and Negative Syndrome Scale (PANSS) was used in diagnosis and assessment. A statistically significant association was observed between rs11536889, rs1927911 and rs1927914, but no association was found between rs10759931. There was no association between the different SNP genotypes and PANSS, except between rs1927914 and general psychopathologic symptoms. This study shows a strong association between TLR4 rs11356889 and rs1927911 minor alleles and schizophrenia. These findings could be additional evidence for the immune system's role in schizophrenia development. However, more studies with a more significant sample number, TLR4 protein assessment, and a larger number of SNPs are recommended.

Retinal Pigment Epithelium Expressed Toll-like Receptors and Their Potential Role in Age-Related Macular Degeneration

(1) Background: Inflammation is a major pathomechanism in the development and progression of age-related macular degeneration (AMD). The retinal pigment epithelium (RPE) may contribute to retinal inflammation via activation of its Toll-like receptors (TLR). TLR are pattern recognition receptors that detect the pathogen- or danger-associated molecular pattern. The involvement of TLR activation in AMD is so far not understood. (2) Methods: We performed a systematic literature research, consulting the National Library of Medicine (PubMed). (3) Results: We identified 106 studies, of which 54 were included in this review. Based on these studies, the current status of TLR in AMD, the effects of TLR in RPE activation and of the interaction of TLR activated RPE with monocytic cells are given, and the potential of TLR activation in RPE as part of the AMD development is discussed. (4) Conclusion: The activation of TLR2, -3, and -4 induces a profound pro-inflammatory response in the RPE that may contribute to (long-term) inflammation by induction of pro-inflammatory cytokines, reducing RPE function and causing RPE cell degeneration, thereby potentially constantly providing new TLR ligands, which could perpetuate and, in the long run, exacerbate the inflammatory response, which may contribute to AMD development. Furthermore, the combined activation of RPE and microglia may exacerbate neurotoxic effects.

Toll-like receptor 4 gene polymorphisms rs4986790 and rs4986791 and age-related macular degeneration susceptibility: a meta-analysis

Background: Several studies have investigated two single nucleotide polymorphisms (SNPs) (rs4986790 and rs4986791) of toll-like receptor 4 (TLR4) and age-related macular degeneration (AMD) susceptibility. However, their results varied. Here, we performed a systematic review and meta-analysis to investigate the association between these two SNPs and AMD susceptibility.Materials and Methods: We searched the PubMed and Web of Science databases for articles indexed up to July 20, 2019. Studies investigating the association between TLR4 polymorphisms rs4986790 (Asp299Gly) and rs4986791 (Thr399Ile) and AMD susceptibility were included in this systematic review. The results of the included studies were pooled with allele contrast, recessive, dominant and overdominant models. The quality of the included studies was assessed using the Newcastle-Ottawa Scale. Egger's test was used to evaluate publication bias.Results: Six studies with 9 cohorts were included in this systematic review and meta-analysis. The recessive and overdominant models showed that rs4986790 was significantly associated with AMD susceptibility, with odds ratios (ORs) of 0.73 and 1.41, respectively. By contrast, rs4986791 was not associated with AMD susceptibility. No publication bias was observed for either rs4986791 or rs4986790.Conclusion: The current evidence supports the hypothesis that rs4986790 but not rs4986791 is associated with AMD susceptibility.