Coordinated activity among islet cells is necessary for glucose homeostasis. Chronic exposure to diabetogenic factors such as pro-inflammatory cytokines, perturbs islet cell crosstalk and β-cell function in diabetes. Secretory nanovesicles - exosomes (EXO) derived from cytokine exposed β-cells modulate physiological and pathological responses to β-cell stress. However, the mechanisms governing this process remain unknown. We tested the hypothesis that β-cell failure in diabetes is mediated in part through β-cell autocrine release of pro-inflammatory EXO to promote inflammation and inhibit β-cell function. Assessment of EXO concentrations from Min6 β-cells exposed to diabetogenic cytokines (IL-1β, TNF-α, and IFNγ, cytoEXO) revealed a 2-fold increase in EXO secretion (p<.05, vs. control (ctl) EXO). While acute inhibition of EXO formation with the compound GW4869 (neutral sphingomyelinase inhibitor) showed significant restoration in β-cell function (GSIS) in cytokine-exposed mouse and human islets (∼7 and 2 fold vs. cytokines alone, p<.05). Moreover, functional assessment of mouse islets exposed to cytoEXO (48h) resulted in suppression of GSIS (∼55%, vs. untreated, p<.05). Identification of cytoEXO content through proteomic analysis revealed a significant upregulation of the chemokine, CXCL10 (∼40 fold vs. ctlEXO) and RNA-Seq analysis of cytoEXO treated mouse islets depicted a marked upregulation of transcripts associated with CXCL10-CXCR3 signaling (p<.001) and subsequent downstream pathways (e.g., NFκB; p=.016 and JAK/STAT; p=.021). Furthermore, inhibition of cytoEXO (GW4869) with cytokines markedly decreased CXCL10 (∼30%) and CXCR3 (∼65%) expression in Min6 cells. These data suggests that cytokines enhance CXCL10 expression in β-cell EXO to enhance inflammation-induced diabetes through EXO-autocrine release of CXCL10 consequently activating CXCR3 signaling and downstream pathways to impair β-cell function.
N. Javeed: None. T.K. Her: None. M. Brown: None. P.M. Vanderboom: None. A.M. Egan: None. A. Vella: Advisory Panel; Self; vTv Therapeutics, Zealand Pharma A/S. Research Support; Self; Novo Nordisk A/S, Xeris Pharmaceuticals, Inc. I.R. Lanza: None. T. Patel: None. A. Matveyenko: None.