The location of sensing determines the pancreatic β-cell response to the viral mimetic dsRNA

Abstract

Viral infection is an environmental trigger that has been suggested to initiate pancreatic β-cell damage, leading to the development of autoimmune diabetes. Viruses potently activate the immune system and can damage β cells by either directly infecting them or stimulating the production of secondary effector molecules (such as proinflammatory cytokines) during bystander activation. However, how and where β cells recognize viruses is unclear, and the antiviral responses that are initiated following virus recognition are incompletely understood. In this study, we show that the β-cell response to dsRNA, a viral replication intermediate known to activate antiviral responses, is determined by the cellular location of sensing (intracellular versus extracellular) and differs from the cellular response to cytokine treatment. Using biochemical and immunological methods, we show that β cells selectively respond to intracellular dsRNA by expressing type I interferons (IFNs) and inducing apoptosis, but that they do not respond to extracellular dsRNA. These responses differ from the activities of cytokines on β cells, which are mediated by inducible nitric oxide synthase expression and β-cell production of nitric oxide. These findings provide evidence that the antiviral activities of type I IFN production and apoptosis are elicited in β cells via the recognition of intracellular viral replication intermediates and that β cells lack the capacity to respond to extracellular viral intermediates known to activate innate immune responses.

Inhibition of mitochondrial oxidative metabolism attenuates EMCV replication and protects β-cells from virally mediated lysis

“…As a positive control for these studies, MIN6 cells were transfected with the synthetic dsRNA compound polyinosinic:polycytidylic acid (polyI:C), which induces expression of both IFN-β and ISGs ( Fig. 2 , B – D ) ( 45 ). The protective actions of nitric oxide also do not require de novo gene expression as the host transcription inhibitor actinomycin D does not modify the protective actions of DETA/NO on EMCV-mediated MIN6 lysis ( Fig.…”

“…Further, the type 1 IFN response is not activated under conditions in which nitric oxide affords protection against EMCV, as mRNA expression of IFN-β and the interferon stimulated gene MX2 are not induced in MIN6 cells infected with EMCV in the presence or absence of 150 µM DETA/NO ( Figure 2D). As a positive control for these studies, MIN6 cells were transfected with the synthetic double stranded RNA (dsRNA) compound polyinosinic:polycytidylic acid (polyI:C), which induces expression of both IFNβ and ISGs ( Figure 2B-D) (45). The protective actions of nitric oxide also do not require de novo gene expression as the host transcription inhibitor actinomycin D does not modify the protective actions of DETA/NO on EMCV-mediated MIN6 lysis ( Figure 2E).…”

“…The mechanism through which nitric oxide attenuates EMCV-mediated β-cell lysis ( Figure 1) is distinct from classical antiviral recognition, namely, the induction of type 1 IFNs (IFN-α and IFN-β) and the expression of antiviral genes (40,41). While dsRNA, produced as an intermediate during viral replication, is recognized by host dsRNA sensors leading to the induction of the type 1 IFN response (45,60,61), EMCV circumvents this response by expressing the L protein. This protein inhibits cytosolic dsRNA sensor antiviral responses by binding to and inhibiting Ran-GTPase and thereby preventing the nuclear translocation of transcription factors required for IFN expression (42)(43)(44).…”

Regulation of ATR-dependent DNA damage response by nitric oxide

“…MEF were cultured in DMEM containing either 25 mM glucose or 10 mM d -galactose, with 10% FBS, 1 mM pyruvate, 2 mM l -glutamine, and 10 mM HEPES ( 28 , 69 ). Other cell lines used (EndoC-βH1, RINm5F, MIN6, and RAW264.7 cells) were cultured as previously described without penicillin and streptomycin ( 68 , 70 , 71 , 72 ). Islets were isolated from Sprague–Dawley rats and C57BL/6J mice and were prepared as previously described ( 73 , 74 , 75 ).…”

Pathology, Risk Factors, and Oxidative Damage Related to Type 2 Diabetes‐Mediated Alzheimer’s Disease and the Rescuing Effects of the Potent Antioxidant Anthocyanin

“…Upon exposure to the virus infection, the immune system of the pancreas becomes activated and initiates the release of inflammatory cytokines, which later cause beta-cell damage. The important viruses that are involved in the infection of pancreatic beta-cells are enterovirus, congenital rubella, and cytomegalovirus [74][75][76][77].…”