IRAK2 and TLR10 confer risk of Hashimoto’s disease: a genetic association study based on the Han Chinese population

Analysis of TLR10 gene polymorphisms in patients with rheumatoid arthritis

OBJECTIVE

Rheumatoid arthritis (RA) is a chronic systemic disease characterized by inflammatory synovitis, and genetic factors play the greatest role in RA. This study aimed to investigate the relationship between Toll-like receptor 10(TLR10) gene polymorphisms and susceptibility to RA.

METHODS

A total of 271 patients with RA and an equal number of healthy controls were included, and the TLR10 rs2101521, rs10004195 and rs11725309 loci were genotyped by time-of-flight mass spectrometry.

RESULTS

Compared with healthy controls, Individuals carrying the rs2101521 G allele had an increased risk of developing RA (P = 0.01; odds ratio (OR) = 1.367; 95 % confidence interval (CI): 1.076-1.736). Individuals with the rs2101521 GG genotype had a greater risk of RA (P = 0.01; OR = 1.816; 95 % CI: 1.161-2.984). Stratified analysis demonstrated a greater prevalence of positive anti-cyclic citrullinated peptide (CCP)antibody in patients carrying the rs2101521 G allele (P = 0.03). Additionally, patients with the rs11725309 CT genotype had elevated levels of C-reactive protein (CRP)(P = 0.007).

CONCLUSION

In conclusion, TLR10 gene polymorphisms are associated with RA susceptibility.

Structural modelling and dynamics of full-length of TLR10 sheds light on possible modes of dimerization, ligand binding and mechanism of action

Toll like receptors (TLRs) play a pivotal role in innate and adaptive immunity. There are 10 TLRs in the human genome, of which TLR10 is the least characterized. Genetic polymorphism of TLR10 has been shown to be associated with multiple diseases including tuberculosis and rheumatoid arthritis. TLR10 consists of an extracellular domain (ECD), a single-pass transmembrane (TM) helix and intracellular TIR (Toll/Interleukin-1 receptor) domain. ECD is employed for ligand recognition and the intracellular domain interacts with other TIR domain-containing adapter proteins for signal transduction. Experimental structure of ECD or TM domain is not available for TLR10. In this study, we have modelled multiple forms of TLR10-ECD dimers, such as closed and open forms, starting from available structures of homologues. Subsequently, multiple full-length TLR10 homodimer models were generated by utilizing homology modelling and protein-protein docking. The dynamics of these models in membrane-aqueous environment revealed the global motion of ECD and TIR domain towards membrane bilayer. The TIR domain residues exhibited high root mean square fluctuation compared to ECD. The 'closed form' model was observed to be energetically more favorable than 'open form' model. The evaluation of persistent interchain interactions, along with their conservation score, unveiled critical residues for each model. Further, the binding of dsRNA to TLR10 was modelled by defined and blind docking approaches. Differential binding of dsRNA to the protomers of TLR10 was observed upon simulation that could provide clues on ligand disassociation. Dynamic network analysis revealed that the 'open form' model can be the functional form while 'closed form' model can be the apo form of TLR10.

A tissue-level phenome-wide network map of colocalized genes and phenotypes in the UK Biobank

Phenome-wide association studies identified numerous loci associated with traits and diseases. To help interpret these associations, we constructed a phenome-wide network map of colocalized genes and phenotypes. We generated colocalized signals using the Genotype-Tissue Expression data and genome-wide association results in UK Biobank. We identified 9151 colocalized genes for 1411 phenotypes across 48 tissues. Then, we constructed bipartite networks using the colocalized signals in each tissue, and showed that the majority of links were observed in a single tissue. We applied the biLouvain clustering algorithm in each tissue-specific network to identify co-clusters of genes and phenotypes. We observed significant enrichments of these co-clusters with known biological and functional gene classes. Overall, the phenome-wide map provides links between genes, phenotypes and tissues, and can yield biological and clinical discoveries.

TLR10: Insights, controversies and potential utility as a therapeutic target

The Toll-like receptor (TLR) family acts as a bridge connecting innate and acquired immunity. TLR10 remains one of the least understood members of this family. Some studies have examined TLR10 ligands, dimerization of TLR10 with other TLRs, and downstream signalling pathways and functions, but they have often arrived at conflicting conclusions. TLR10 can induce the production of proinflammatory cytokines by forming homodimers with itself or heterodimers with TLR1 or other TLRs, but it can also inhibit proinflammatory responses when co-expressed with TLR2 or potentially other TLRs. Mutations in the Toll/Interleukin 1 receptor (TIR) domain of TLR10 alter its signalling activity. Polymorphisms in the TLR10 gene can change the balance between pro- and anti-inflammatory responses and hence modulate the susceptibility to infection and autoimmune diseases. Understanding the full range of TLR10 ligands and functions may allow the receptor to be exploited as a therapeutic target in inflammation- or immune-related diseases. Here, we summarize recent findings on the pro- and anti-inflammatory roles of TLR10 and the molecular pathways in which it is implicated. Our goal is to pave the way for future studies of the only orphan TLR thought to have strong potential as a target in the treatment of inflammation-related diseases.

Polymorphisms of IRAK1 Gene on X Chromosome Is Associated with Hashimoto Thyroiditis in Korean Children

Autoimmune thyroid disease (AITD) is predominant in females and has been focused on the sexual diploid in immune response. The IL-1 receptor-associated kinase 1 (IRAK1) gene on the X chromosome was recently suggested as strong autoimmune disease-susceptible loci, second to the major histocompatibility complex region. We investigated the frequency of IRAK1 single-nucleotide polymorphisms (SNPs) in children with AITD. In this study, we observed that SNPs of IRAK1 including rs3027898, rs1059703, and rs1059702 in 115 Korean AITD pediatric patients (Graves' disease = 74 [females = 52/males = 22]; Hashimoto disease [HD] = 41 [females = 38/males = 3]; thyroid-associated ophthalmopathy [TAO] = 40 (females = 27/males = 13); without TAO = 75 (females = 63/males = 12); total males = 25, total females = 90; mean age = 11.9 years) and 204 healthy Korean individuals (males = 104/females = 100). The data from cases and controls were analyzed from separate sex-stratified or all combined by χ 2 test for categorical variables and Student t test for numerical variables. Our study revealed that SNPs of IRAK1-associated HD and without TAO but Graves' disease and TAO were not found significant. When cases and controls were analyzed by separate sex, we found that rs3027898 AA, rs1059703 AA, and rs1059702 GG showed disease susceptibility in female AITD, HD, and without TAO. Also, all rs3027898, rs1059703, and rs1059702 were found to be in strong linkage disequilibrium (D' = 0.96-0.98, r2 = 0.83-0.97). The haplotype of 3 SNPs was higher in AITD than in controls (CGA, r2 = 5.42, P = 0.019). Our results suggest that IRAK1 polymorphisms may contribute to the pathogenesis of HD, AITD, and without thyroid-associated ophthalmopathy for females.

TLR10 and Its Unique Anti-Inflammatory Properties and Potential Use as a Target in Therapeutics

TLRs are pattern recognition receptors (PRRs) whose cytoplasmic signalling domain is similar to that of IL-1. The extracellular domain of TLRs serve as the binding site of pathogen associated molecular patterns. TLRs are found on both plasma and endosomal membranes and they mainly exert their function by activating genes which lead to production of inflammatory factors. The latest TLR to be discovered, TLR10 is a unique TLR which exhibit anti-inflammatory properties. TLR10 is found on the plasma membrane with other TLRs namely TLR1, TLR2, TLR4, TLR5 and TLR6. Studies have revealed that TLR10 is found on the same gene cluster with TLR1 and TLR6 and is also a coreceptor of TLR2. Up to date, TLR10 is the only TLR which exhibit anti-inflammatory property. Previously, TLR10 was thought to be an “orphan receptor” but much recent studies have identified ligands for TLR10. Currently there is no review article on TLR10 that has been published. In this narrative review, we are going to give an account of TLR10, its functions mainly as an anti-inflammatory PRR and its possible applications as a target in therapeutics.