Contribution of KIR genes, HLA class I ligands, and KIR/HLA class I ligand combinations on the genetic predisposition to celiac disease and coexisting celiac disease and type 1 diabetes mellitus

New Evidence in the Pathogenesis of Celiac Disease and Type 1 Diabetes Mellitus: A Systematic Review

Celiac disease (CD) and type 1 diabetes mellitus (T1DM) are autoimmune diseases that coexist frequently. These illnesses share a common genetic background. This study aims to review the different pathophysiologic mechanisms that have been studied about the coexistence of CD and T1DM, to contrast them, and to summarize their specific role in these autoimmune diseases. We conducted a systematic review following the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) checklist and used the Medical Subject Headings (MeSH) search strategy to obtain relevant articles. We found 585 papers which were reduced to 355 after removing duplicates. Later, the filters and inclusion/exclusion criteria were applied which ended the search with 78 articles. Finally, we reviewed the articles that contained information about the pathogenesis of CD and T1DM, their coexistence, and how the pathogenesis impacts clinical outcomes. The reviewed studies strongly conclude that the presence of human leukocyte antigen (HLA) genes DQ2 and DQ8 are high-risk for developing the coexistence of CD and T1DM. We found that killer immunoglobulin-like receptor (KIR) genes, enterovirus infection in gut cells, and gut microbiota dysbiosis with the predominance of Bacteroides spp. also play a role in the pathogenesis and development of symptoms of CD in patients with the previous diagnosis of T1DM. CD4+ and CD8+ cell levels vary among patients and studies, consequently, more study on this topic is needed.

Association of KIR gene polymorphisms with Type 1 Diabetes: a meta-analysis

Purpose

Type 1 Diabetes (T1D) is a T cell-mediated disease, in which autoimmune destruction of insulin-producing β-cells in pancreatic islets occurs. In recent decades, the role of Killer cell immunoglobulin-like receptor (KIR) gene polymorphisms in susceptibility to T1D has been demonstrated in an increased number of studies. Nonetheless, inconsistency has been observed in the results of performed association studies. To comprehensively clarify the association among KIR gene polymorphisms and the risk of T1D, this meta-analysis on the previously published association studies was carried out via incorporating multiple research.

Methods

No publication has been recorded from Nov 2017 until July 2020 about the KIR genes and T1D. The PubMed/MEDLINE and Scopus databases were systematically searched up to November 2017 to identify investigations on the impact of the polymorphisms of KIR genes on susceptibility to T1D. The odds ratio (OR) with a 95% confidence interval (95% CI) was calculated. Funnel plot and Egger test were used to assess the publication bias. Thirteen qualified published case-control articles were found for evaluation in this meta-analysis.

Results

Our results show statistical significance between the genetic variations in the KIR2DL1 (OR = 0.42, 95% CI = 0.23-0.77; P = 0.005), KIR2DL2 (OR = 1.15, 95% CI = 1.00-1.32; P = 0.048), and KIR2DL5 (OR = 0.86, 95% CI = 0.75-0.98; P = 0.03) with susceptibility to T1D.

Conclusions

This meta-analysis study provides reliable evidence that KIR gene polymorphisms may contribute to T1D risk. KIR 2DL1 and 2DL5 genes might be considered as a protective factor for T1D, while 2DL2 seemed to be a susceptibility factor.