Type 1 diabetes (T1D) is an autoimmune disease resulting from the self-destruction of insulin-producing β-cells. Reduced neutrophil counts have been observed in patients with T1D. However, the pathological roles of neutrophils in the development of T1D remain unknown. Here we show that circulating protein levels and enzymatic activities of neutrophil elastase (NE) and proteinase 3 (PR3), both of which are neutrophil serine proteases stored in neutrophil primary granules, were markedly elevated in patients with T1D, especially those with disease duration of less than 1 year. Furthermore, circulating NE and PR3 levels increased progressively with the increase of the positive numbers and titers of the autoantibodies against β-cell antigens. An obvious elevation of NE and PR3 was detected even in those autoantibody-negative patients. Increased NE and PR3 in T1D patients are closely associated with elevated formation of neutrophil extracellular traps. By contrast, the circulating levels of α1-antitrypsin, an endogenous inhibitor of neutrophil serine proteases, are decreased in T1D patients. These findings support an early role of neutrophil activation and augmented neutrophil serine proteases activities in the pathogenesis of β-cell autoimmunity and also suggest that circulating NE and PR3 may serve as sensitive biomarkers for the diagnosis of T1D.

Inflammatory cytokines have a critical role in the progressive deterioration of pancreatic β-cell function and development of type 1 diabetes. Prolonged exposure of β-cells to inflammatory cytokines results in gene expression modifications, leading to loss of β-cell function. MicroRNAs (miRNAs) are small non-coding RNAs acting as key regulators of gene expression. Here, we demonstrate that miR-101a and miR-30b are key players in cytokine-mediated β-cell dysfunction. We found that IL-1β induces an increase in miR-101a and miR-30b in MIN6 cells, and that the two miRNAs participate in β-cell dysfunction, including decreased insulin content, gene expression, and increased β-cell death. miR-101a and miR-30b reduce proinsulin expression and insulin content by directly targeting the transcriptional factor Neurod1. In addition, β-cell apoptosis mediated by miR-101a and miR-30b is associated with diminished expression level of the antiapoptotic protein Bcl2. Moreover, we show that miR-101a causes an impairment in glucose-induced insulin secretion by decreasing the expression of the transcription factor Onecut2. Taken together, our findings suggest that changes in the levels of miR-101a and miR-30b contribute to cytokine-mediated β-cell dysfunction occurring during the development and progression of type 1 diabetes.

BackgroundFibroblast growth factor 21 (FGF21), a glucose and lipid metabolic regulator, has recently been demonstrated to be associated with cardiovascular diseases (CVD) such as carotid atherosclerosis, coronary heart disease and carotid artery plaques. However, the relationship between circulating FGF21 and subclinical atherosclerosis or atherosclerosis of other arteries such as the femoral and iliac artery remains unclear. In this study, we evaluated the association of serum FGF21 with intima-media thickness (IMT) and subclinical atherosclerosis in type 2 diabetic patients.MethodsSerum FGF21 levels were detected by enzyme-linked immunosorbent assay in 212 newly diagnosed type 2 diabetic patients without clinical symptoms of atherosclerosis or cardiovascular diseases. IMT of the carotid, femoral, and iliac arteries were measured by high-resolution B-mode ultrasound to determine the presence of subclinical atherosclerosis, which was defined as having an IMT > 1.0 mm and/or plaque on one or more of the three arteries without any clinical manifestations. The relationship between serum FGF21 levels and subclinical atherosclerosis was analyzed.ResultsSerum FGF21 levels were significantly higher in patients with subclinical atherosclerosis compared to those without [261.3 (135.1–396.4) versus 144.9 (95.9–223.0) ng/L, P < 0.001]. These differences were also observed in both men and women with subclinical atherosclerosis compared to their respective groups without [men: 243.2 (107.6–337.0) versus 136.8 (83.6–212.8) ng/L, P = 0.048; women: 292.4 (174.2–419.9) versus 160.4 (115.3–258.5) ng/L, P = 0.001]. Moreover, serum FGF21 levels showed a significantly positive correlation with carotid IMT in women (r = 0.23, P = 0.018) and with iliac IMT in both genders (women: r = 0.27, P = 0.005; men: r = 0.22, P = 0.024). Multiple logistic regression analysis further showed that serum FGF21 was an independent impact factor for subclinical atherosclerosis in patients with type 2 diabetes.ConclusionsSerum FGF21 is elevated in newly diagnosed type 2 diabetes, and positively correlates with carotid and iliac lesions in patients with subclinical atherosclerosis, especially in women. High levels of FGF21 may be a compensatory reaction to offset atherosclerosis.

Background. Fulminant type 1 diabetes (FT1D) is a novel subtype of type 1 diabetes characterized by extremely rapid onset and complete deficiency of insulin due to the destruction of pancreatic β cells. However, the precise mechanisms underlying the etiology of this disease remain unclear. Methods. A total of 22 patients with FT1D and 10 healthy subjects were recruited. Serum antibodies to GAD, IA2, and ZnT8 in patients were tested. And peripheral T cell responses to GAD65, insulin B9–23 peptide, or C peptide were determined in 10 FT1D patients and 10 healthy controls. The mRNA levels of several related cytokines and molecules, such as IFN-γ, IL-4, RORC, and IL-17 in PBMCs from FT1D patients were analyzed by qRT-PCR. Result. We found that a certain proportion of Chinese FT1D patients actually have developed islet-related autoantibodies after onset of the disease. The GAD, insulin, or C peptide-reactive T cells were found in some FT1D patients. We also detected a significant increase for IFN-γ expression in FT1D PBMCs as compared with that of healthy controls. Conclusion. Autoimmune responses might be involved in the pathogenesis of Chinese FT1D.

Pancreatic beta cell failure is the hallmark of type 1 diabetes (T1D). Recent studies have suggested that pathogen recognizing receptors (PRRs) are involved in the survival, proliferation and function of pancreatic beta cells. So far, little is known about the role of alpha-protein kinase 1 (ALPK1), a newly identified cytosolic PRR specific for ADP-β-D-manno-heptose (ADP-heptose), in beta cell survival. In current study we aimed to fill the knowledge gap by investigating the role of Alpk1 in the apoptosis of MIN6 cells, a murine pancreatic beta cell line. We found that the expression of Alpk1 was significantly elevated in MIN6 cells exposed to pro-inflammatory cytokines, but not to streptozotocin, low-dose or high-dose glucose. Activation of Alpk1 by ADP heptose alone was insufficient to induce beta cell apoptosis. However, it significantly exacerbated cytokine-induced apoptosis in MIN6 cells. Mechanistic investigations showed that Alpk1 activation was potent to further induce the expression of tumor necrosis factor (TNF)-α and Fas after cytokine stimulation, possibly due to enhanced activation of the TIFA/TAK1/NF-κB signaling axis. Treatment of GLP-1 receptor agonist decreased the expression of TNF-α and Fas and improved the survival of beta cells exposed to pro-inflammatory cytokines and ADP heptose. In summary, our data suggest that Alpk1 sensitizes beta cells to cytokine-induced apoptosis by potentiating TNF-α signaling pathway, which may provide novel insight into beta cell failure and T1D development.