Search

Certain HLA class II genes increase the risk for type 1 diabetes (T1D) development while others provide protection from disease development. HLA class II alleles encode MHC proteins on antigen-presenting cells, which function to present peptides and activate CD4 T cells. The DRB1*15:01 (DR15)-DQA1*01:02-DQB1*06:02 (DQ6) haplotype provides dominant protection across all stages of T1D and is a common haplotype found in Caucasians. However, it is present in

T-cell responses to posttranslationally modified self-antigens are associated with many autoimmune disorders. In type 1 diabetes, hybrid insulin peptides (HIPs) are implicated in the T-cell–mediated destruction of insulin-producing β-cells within pancreatic islets. The natural history of the disease is such that it allows for the study of T-cell reactivity prior to the onset of clinical symptoms. We hypothesized that CD4 T-cell responses to posttranslationally modified islet peptides precedes diabetes onset. In a cohort of genetically at-risk individuals, we measured longitudinal T-cell responses to native insulin and hybrid insulin peptides. Both proinflammatory (interferon-γ) and antiinflammatory (interluekin-10) cytokine responses to HIPs were more robust than those to native peptides, and the ratio of such responses oscillated between pro- and antiinflammatory over time. However, individuals who developed islet autoantibodies or progressed to clinical type 1 diabetes had predominantly inflammatory T-cell responses to HIPs. Additionally, several HIP T-cell responses correlated to worsening measurements of blood glucose, highlighting the relevance of T-cell responses to posttranslationally modified peptides prior to autoimmune disease development.

Certain human leucocyte antigen (HLA) class II genes increase the risk for type 1 diabetes (T1D) development while others provide protection from disease development. HLA class II alleles encode major histocompatibility complex proteins on antigen presenting cells, which function to present peptides and activate CD4 T-cells. The DRB1*15:01 (DR15)-DQA1*01:02-DQB1*06:02 (DQ6) haplotype provides dominant protection across all stages of T1D and is a common haplotype found in Caucasians but present in DQB1*06:02-mediated protection. We describe a T1D cohort with DQB1*06:02 (n=50) and compare them to individuals with T1D and without DQB1*06:02 (n=2,759) that were identified over the last 26 years at the Barbara Davis Center for Diabetes. The age at diagnosis was similar between the cohorts and normally distributed throughout childhood and early adulthood. The average hemoglobin A1c was 10.8 ± 2.8% (95 ± 7mmol/mol) at diagnosis in those DQB1*06:02+. The majority of T1D DQB1*06:02+ individuals were positive for one or more islet autoantibodies; however, there was a greater proportion that were islet autoantibody negative compared to those T1D DQB1*06:02- individuals. Interestingly, DQB1*03:02, which confers significant T1D risk, was only present in those DQB1*06:02+ individuals with islet autoantibodies. This is one of the largest studies examining patients presenting with clinical T1D in the presence of DQB1*06:02, which provides a population to study the mechanisms of failed genetic protection against T1D.

Certain HLA class II genes increase the risk for type 1 diabetes (T1D) development while others provide protection from disease development. HLA class II alleles encode MHC proteins on antigen-presenting cells, which function to present peptides and activate CD4 T cells. The DRB1*15:01 (DR15)-DQA1*01:02-DQB1*06:02 (DQ6) haplotype provides dominant protection across all stages of T1D and is a common haplotype found in Caucasians. However, it is present in

The major genetic determinant in susceptibility or protection from many autoimmune diseases resides in the human leukocyte antigen (HLA) region. Specific class II alleles (e.g., HLA-DQ8) increase the risk for developing type 1 diabetes (T1D), a prototypical organ specific autoimmune disease, whereas HLA-DQ6 leads to dominant protection. We hypothesize that DQ6 is protective via its ability to present insulin peptides to regulatory CD4+ T cells (Tregs), resulting in anti-inflammatory responses. We expanded insulin-specific Tregs from peripheral blood mononuclear cells (PBMCs) of DQ6+ non-diabetic individuals using an insulin peptide. Insulin-expanded Tregs were flow sorted, and paired single-cell TCR/RNA-seq (10X Genomics) was performed. Of 2,096 insulin-expanded Tregs from three DQ6+ individuals, 883 αβTCRs (42%) were present ≥2 times, and we confirmed the antigen specificity of dominant clonotypes. The single-cell RNA-seq data showed 4 clusters of Treg cells based on the expression levels of FOXP3 and IL-2RA. Additionally, we flow-sorted CD4+ T cells from the pancreatic islets of a non-diabetic DQ6+ organ donor and performed single-cell TCR sequencing. Of the 67 CD4+ cells, TCR clonotypes from three cells possessed identical TCRα chains (including CDR3 sequences) with Tregs sequenced from the PBMCs of the separate DQ6+ non-diabetic individuals. These data indicate the potential presence of insulin-specific Tregs within the pancreatic islets of non-diabetic organ donors. Our findings provide a mechanistic basis for understanding HLA-linked protection from autoimmune diabetes development and have implications for manipulating self-antigen-specific T cell responses to modify the disease course in T1D.

Introduction Highly seasonal animals demonstrate predictable changes in immune function that coincide with changes in photoperiod. Little is known about the effect of season on immune response in baboons. The objective of this study was to determine the effect of season on inflammatory response in baboons. Materials and Methods Peripheral blood mononuclear cell cytokine response following immune stimulation and serum markers of inflammation were assessed during each season in two groups of young male baboons: one housed under natural light and one in a controlled environment of 12 hours light:12 hours dark. Results A seasonal immune rhythm was evident in both groups, with a greater TNF-α and IL-6 response to stimulation and serum CRP concentration in June and September compared with December. Conclusions Season is an important experimental confounder, and therefore, time of year should be controlled when designing studies and analyzing data from immune studies in baboons.

Baboons are an ideal model for studies of human inflammatory response due to their physiological and immunological similarities to people; however; little is known about how age affects immune function in the baboon. We sought to determine if baboons show age-related innate immune changes similar to that described in people. Age was correlated with increased serum C-reactive protein and interleukin-6 or, however, no change in interleukin-10 concentration was observed (n = 120 baboons). Cytokine release from unstimulated peripheral blood mononuclear cells as well as following immune (lipopolysaccharide) stimulation increased with age. When whole blood was assayed, both lipopolysaccharide stimulated and unstimulated samples showed an age-related increase in interleukin-6 response, although the unstimulated cytokine response was reduced compared with that observed in peripheral blood mononuclear cells. Tumor necrosis factor-α response was not related to age. Cytokine response in lipopolysaccharide-stimulated whole blood was negatively correlated with serum DHEA-S concentration and positively correlated with TGF-β concentration.