Altered Frequency and Phenotype of HLA-G-Expressing DC-10 in Type 1 Diabetes Patients at Onset and in Subjects at Risk to Develop the Disease

IL-10-producing regulatory cells impact on celiac disease evolution

Celiac Disease (CD) is a T-cell mediated disorder caused by immune response to gluten, although the mechanisms underlying CD progression are still elusive. We analyzed immune cell composition, plasma cytokines, and gliadin-specific T-cell responses in patients with positive serology and normal intestinal mucosa (potential-CD) or villous atrophy (acute-CD), and after gluten-free diet (GFD). We found: an inflammatory signature and the presence of circulating gliadin-specific IFN-γ+ T cells in CD patients regardless of mucosal damage; an increased frequency of IL-10-secreting dendritic cells (DC-10) in the gut and of circulating gliadin-specific IL-10-secreting T cells in potential-CD; IL-10 inhibition increased IFN-γ secretion by gliadin-specific intestinal T cells from acute- and potential-CD. On GFD, inflammatory cytokines normalized, while IL-10-producing T cells accumulated in the gut. We show that IL-10-producing cells are fundamental in controlling pathological T-cell responses to gluten: DC-10 protect the intestinal mucosa from damage and represent a marker of potential-CD.

The + 3010/C single nucleotide polymorphism (rs1710) at the HLA-G 3' untranslated region is associated with a short transcript exhibiting a deletion of 92 nucleotides

The physiological expression of HLA-G is mainly observed in the placenta, playing an essential role in maternal-fetal tolerance. Among the HLA-G mRNA alternative transcripts, the one lacking 92 bases at the HLA-G 3' untranslated region (3'UTR), the 92bDel transcript, is more stable, is associated with increased HLA-G soluble levels, and was observed in individuals presenting a 14 bp insertion (14 bp⁺) at the 3'UTR. We investigated the presence of the 92bDel transcript in placenta samples, correlating its expression levels with the HLA-G polymorphisms at the 3'UTR. The 14 bp⁺ allele correlates with the presence of the 92bDel transcript. However, the polymorphism triggering this alternative splicing is the + 3010/C allele (rs1710, allele C). Most 14 bp⁺ haplotypes (UTR-2/-5/-7) present allele + 3010/C. However, 14 bp^- haplotypes such as UTR-3 are also associated with + 3010/C, and the 92bDel transcript can be detected in homozygous samples for the 14 bp- allele carrying at least one copy of UTR-3. The UTR-3 haplotype is associated with alleles G*01:04 and the HLA-G lineage HG0104, which is a high-expressing lineage. The only HLA-G lineage that is not likely to produce this transcript is HG010101, associated with the + 3010/G allele. This functional difference may be advantageous, considering the high worldwide frequency of the HG010101 lineage. Therefore, HLA-G lineages are functionally distinct regarding the 92bDel transcript expression, and the 3010/C allele triggers the alternative splicing that produces this shorter and more stable transcript.

Alteration of interleukin-10-producing Type 1 regulatory cells in autoimmune diseases

PURPOSE OF REVIEW

This review highlights findings describing the role of interleukin (IL)-10-producing Type 1 regulatory T (Tr1) cells in controlling autoimmune diseases and possible approaches to restore their function and number.

RECENT FINDINGS

Reduced frequency and/or function of cell subsets playing a role in Tr1 cell induction (e.g., DC-10 and Bregs), was found in patients with autoimmunity and may impact on Tr1 cell frequency.

SUMMARY

IL-10 is a pleiotropic cytokine with fundamental anti-inflammatory functions acting as negative regulator of immune responses. IL-10 is critically involved in the induction and functions of Tr1 cells, a subset of memory CD4+ T cells induced in the periphery to suppress immune responses to a variety of antigens (Ags), including self-, allogeneic, and dietary Ags. Alterations in IL-10-related pathways and/or in the frequency and activities of Tr1 cells have been associated to several autoimmune diseases. We will give an overview of the alterations of IL-10 and IL-10-producing Tr1 cells in Multiple Sclerosis, Type 1 Diabetes, and Celiac Disease, in which similarities in the role of these tolerogenic mechanisms are present. Current and future approaches to overcome Tr1 cell defects and restore tolerance in these diseases will also be discussed.

The HLA-G Immune Checkpoint Plays a Pivotal Role in the Regulation of Immune Response in Autoimmune Diseases

The human G-leukocyte antigen (HLA-G) molecule is a non-classical major histocompatibility complex (MHC) class I molecule. The pertinence of HLA-G has been investigated in numerous studies which have sought to elucidate the relevance of HLA-G in pathologic conditions, such as autoimmune diseases, cancers, and hematologic malignancies. One of the main goals of the current research on HLA-G is to use this molecule in clinical practice, either in diagnostics or as a therapeutic target. Since HLA-G antigens are currently considered as immunomodulatory molecules that are involved in reducing inflammatory and immune responses, in this review, we decided to focus on this group of antigens as potential determinants of progression in autoimmune diseases. This article highlights what we consider as recent pivotal findings on the immunomodulatory function of HLA-G, not only to establish the role of HLA-G in the human body, but also to explain how these proteins mediate the immune response.