What the HLA-I!—Classical and Non-classical HLA Class I and Their Potential Roles in Type 1 Diabetes

Rebecca C. Wyatt, Giacomo Lanzoni, Mark A. Russell, Ivan Gerling, Sarah J. Richardson

Research output: Contribution to journalReview articlepeer-review

5 Scopus citations

Abstract

Purpose of Review: Hyperexpression of classical HLA class I (HLA-I) molecules in insulin-containing islets has become a widely accepted hallmark of type 1 diabetes pathology. In comparison, relatively little is known about the expression, function and role of non-classical subtypes of HLA-I. This review focuses on the current understanding of the non-classical HLA-I subtypes: HLA-E, HLA-F and HLA-G, within and outside the field of type 1 diabetes, and considers the possible impacts of these molecules on disease etiology. Recent Findings: Evidence is growing to suggest that non-classical HLA-I proteins are upregulated, both at the RNA and protein levels in the pancreas of individuals with recent-onset type 1 diabetes. Moreover, associations between non-classical HLA-I genotypes and age at onset of type 1 diabetes have been reported in some studies. As with classical HLA-I, it is likely that hyperexpression of non-classical HLA-I is driven by the release of diffusible interferons by stressed β cells (potentially driven by viral infection) and exacerbated by release of cytokines from infiltrating immune cells. Summary: Non-classical HLA-I proteins predominantly (but not exclusively) transduce negative signals to immune cells infiltrating at the site of injury/inflammation. We propose a model in which the islet endocrine cells, through expression of non-classical HLA-I are fighting back against the infiltrating immune cells. By inhibiting the activity and function on NK, B and select T cells, the non-classical HLA-I, proteins will reduce the non-specific bystander effects of inflammation, while at the same time still allowing the targeted destruction of β cells by specific islet-reactive CD8+ T cells.

Original languageEnglish (US)
Article number159
JournalCurrent diabetes reports
Volume19
Issue number12
DOIs
StatePublished - Dec 1 2019

Keywords

  • HLA-E
  • HLA-F
  • HLA-G
  • HLA-I
  • Immune system
  • Non-classical HLA-I
  • Type 1 diabetes

ASJC Scopus subject areas

  • Internal Medicine
  • Endocrinology, Diabetes and Metabolism

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