Immune system activity in Type 1 Diabetes at the onset: data of MINDFUL project

Background. The onset of type 1 diabetes (T1D) has been associated with altered frequency and phenotype of both innate and adaptive immune cells. Furthermore, an altered frequency or function of extracellular vesicles (EVs) could be implicated in the onset of the disease. EVs are small particles released into biological fluids by all cells and play an important role in intracellular communication. Our primary aim is to characterize the immune system and microvesicles involved in children and adolescents at the onset of T1D disease and present in their siblings at risk of developing disease, to identify new early autoimmune disease-specific biomarkers and possible new targets of intervention or prevention. Subjects and Methods. We enrolled 42 subjects with type 1 diabetes at onset, 25 their siblings (S), and 19 healthy subjects (CS) as a control group. The study was conducted between 1st January 2020 and 30 April 2023. At the time of onset, patients are subjected to clinical and metabolic evaluation (HbA1c, c-peptide), as well as peripheral blood sampling for the evaluation of lymphocyte subsets and EVs. These were analyzed by multicolor flow cytometry (BD FACSymphony TM cytometer) using a method capable of identifying them directly on fresh blood without manipulation. Moreover, antibodies staining leukocyte (CD45+), endothelial (CD31+) and platelet (CD31+CD41a+) EVs were used. Results. No auxological differences were present between T1D and CS, while S and CS differed in terms of age, weight, and height (p<0.01). 6/25 S had positive antibodies predisposing to diabetes; in particular, 2/25 had 2 positive autoantibodies. Patients with T1D had higher TG, glucose and HbA1c (p<0.0001) levels and lower c-peptide (p<0.0001), and HDL (p<0.001) than S. At diagnosis, T1D showed Treg memory and intermediate monocyte cell percentages higher than CS (p<0.05). Moreover, T1D had Th1 (p<0.05) and mDC (p<0.01) lymphocyte values lower than S. Siblings and CS differed from each other in percentage number of basophilic, CD8 EM, Treg memory, Treg naive and mDC cells (p<0.01)(unadjusted data). Analyzing MVs, T1D presented leukocyte MV values lower than CS (p<0.01) and S (NS). After adjustment for sex, BMI and age, we found only significant differences in Treg memory and leucocyte MVs between T1D and CS (p<0.05). Conclusion. These results showed cellular changes in Treg memory and leucocyte MVs associated to new onset T1D. The increase of Treg memory and the reduction in leucocyte EVs in peripheral blood could prove to be a biomarker of the acute phase of type 1 diabetes with a “pro-diabetogenic” potential and could lead to new future immunotherapies.