Early Detection of Peripheral Blood Cell Signature in Children Developing β-Cell Autoimmunity at a Young Age

Abstract

The appearance of type 1 diabetes (T1D)-associated autoantibodies is the first and only measurable parameter to predict progression toward T1D in genetically susceptible individuals. However, autoantibodies indicate an active autoimmune reaction, wherein the immune tolerance is already broken. Therefore, there is a clear and urgent need for new biomarkers that predict the onset of the autoimmune reaction preceding autoantibody positivity or reflect progressive β-cell destruction. Here we report the mRNA sequencing–based analysis of 306 samples including fractionated samples of CD4+ and CD8+ T cells as well as CD4−CD8− cell fractions and unfractionated peripheral blood mononuclear cell samples longitudinally collected from seven children who developed β-cell autoimmunity (case subjects) at a young age and matched control subjects. We identified transcripts, including interleukin 32 (IL32), that were upregulated before T1D-associated autoantibodies appeared. Single-cell RNA sequencing studies revealed that high IL32 in case samples was contributed mainly by activated T cells and NK cells. Further, we showed that IL32 expression can be induced by a virus and cytokines in pancreatic islets and β-cells, respectively. The results provide a basis for early detection of aberrations in the immune system function before T1D and suggest a potential role for IL32 in the pathogenesis of T1D.

Immune Transcriptome of Cells Infected with Enterovirus Strains Obtained from Cases of Type 1 Diabetes

“…Interestingly, pathogenetic studies of T1D—a disease in which persistent enteroviral infections are suspected—have provided results compatible with those observed for slow infection due to diabetes-related EV strains. Diabetes studies have indicated that: (a) IL6 is normally expressed in islet beta and alpha cells, but its production is reduced in the pancreas of diabetics [ 37 ]; (b) elevated levels of IL-18 are found in the blood cells of T1D patients and may promote NK cell activation and abrogation of the suppressive capacity of T regulatory cells [ 38 ]; and (c) peripheral blood mononuclear cells of children who developed beta-cell autoimmunity have upregulated IL32 transcripts before the appearance of T1D-associated autoantibodies [ 39 ]. Finally, increased expression of MCP1 has been reported in newly diagnosed T1D children [ 40 ].…”

Molecular interactions and functions of IL-32

“…[26][27][28][29][30][31] Single cell seq studies have demonstrated that Tregs are important sources of IL-32 in various diseases. 13,32,33 Even though IL-32 can be expressed in basal conditions, more typically IL-32 expression is induced or enhanced in response to pro-inflammatory cytokines, infections, and other types of cellular stress such as hypoxia, as briefly outlined in the following section. For a comprehensive overview of IL-32 expression in different cells types, see Tables 1 and 2.…”

“…Expressed by NK cell lines and IL-2-and IL-8-activated NK cells 1,12 Increased expression in NK cells from myelodysplasmic syndromes compared to healthy controls 40 Enhanced NK cell-mediated killing of cancer cells 12 Expressed by NK cells in prediagnostic blood samples from children who developed type 1 diabetes 13 Highly expressed in splenic compared to blood NK cells 41 IL-2 6,40 IL-18 1 IL-12 1…”

Type 1 Diabetes: Interferons and the Aftermath of Pancreatic Beta-Cell Enteroviral Infection

“…Finally, in this context, we note that infection of pancreatic islets with CVB1-7 or stimulation of EndoC-βH1 cells with IL-1β + IFNγ promotes IL-32 expression [ 141 ]. IL-32 isoforms have been implicated in DC maturation and DC-induced chemotaxis of activated CD4+ and CD8+ T cells [ 142 ].…”

“…IL-32 isoforms have been implicated in DC maturation and DC-induced chemotaxis of activated CD4+ and CD8+ T cells [ 142 ]. Interestingly, in HLA-DR-DQ conferred children who developed islet autoantibodies or T1D, elevated expression of IL-32 has been found in CD4+ and CD8+ T cells and NK cells [ 141 ].…”