Apoptotic Cell Death Triggered by Nitric Oxide in Pancreatic β-Cells

Kaneto, Hideaki; Fujii, Junichi; Seo, Han Geuk; Suzuki, Ken; Matsuoka, Taka‐aki; Nakamura, Michio; Tatsumi, Haruyuki; Yamasaki, Yasuomi; Kamada, T; Taniguchi, N

doi:10.2337/diab.44.7.733

Cited by 300 publications

(112 citation statements)

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“…Although IL-1␤ alone appears to be a major effector in the destruction of rat islets, the combinations of proinflammatory cytokines such as TNF-␣ or IFN-␥ were necessary for the induction of mouse or human islet cell death (24). In vitro effects of NO have also been reported, mostly using islet cells from rats (23,36). NO production by cytokine-stimulated islet cells seems to be negligible in species other than rats.…”

Section: Discussionmentioning

confidence: 99%

“…Thus, it appears that TNF-␣ either inhibits or promotes diabetes depending on the condition under which it acts. The effect of IL-1 or NO on islet cell death was studied mostly in vitro (23,24), and their in vivo effects were not demonstrated (14,19). IFN-␥ has been regarded as a sensitizing or immunomodulatory cytokine rather than an effector molecule (25).…”

mentioning

confidence: 99%

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IFN-γ/TNF-α Synergism as the Final Effector in Autoimmune Diabetes: A Key Role for STAT1/IFN Regulatory Factor-1 Pathway in Pancreatic β Cell Death

Suk

Kim

et al. 2001

The Journal of Immunology

208

187

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Fas ligand (FasL), perforin, TNF-α, IL-1, and NO have been considered as effector molecule(s) leading to β cell death in autoimmune diabetes. However, the real culprit(s) in β cell destruction have long been elusive, despite intense investigation. We and others have demonstrated that FasL is not a major effector molecule in autoimmune diabetes, and previous inability to transfer diabetes to Fas-deficient nonobese diabetic (NOD)-lpr mice was due to constitutive FasL expression on lymphocytes from these mice. Here, we identified IFN-γ/TNF-α synergism as the final effector molecules in autoimmune diabetes of NOD mice. A combination of IFN-γ and TNF-α, but neither cytokine alone, induced classical caspase-dependent apoptosis in insulinoma and pancreatic islet cells. IFN-γ treatment conferred susceptibility to TNF-α-induced apoptosis on otherwise resistant insulinoma cells by STAT1 activation followed by IFN regulatory factor (IRF)-1 induction. IRF-1 played a central role in IFN-γ/TNF-α-induced cytotoxicity because inhibition of IRF-1 induction by antisense oligonucleotides blocked IFN-γ/TNF-α-induced cytotoxicity, and transfection of IRF-1 rendered insulinoma cells susceptible to TNF-α-induced cytotoxicity. STAT1 and IRF-1 were expressed in pancreatic islets of diabetic NOD mice and colocalized with apoptotic cells. Moreover, anti-TNF-α Ab inhibited the development of diabetes after adoptive transfer. Taken together, our results indicate that IFN-γ/TNF-α synergism is responsible for autoimmune diabetes in vivo as well as β cell apoptosis in vitro and suggest a novel signal transduction in IFN-γ/TNF-α synergism that may have relevance in other autoimmune diseases and synergistic anti-tumor effects of the two cytokines.

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

IFN-γ/TNF-α Synergism as the Final Effector in Autoimmune Diabetes: A Key Role for STAT1/IFN Regulatory Factor-1 Pathway in Pancreatic β Cell Death

Suk

Kim

et al. 2001

The Journal of Immunology

208

187

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“…On the other hand, there are conflicting data on whether blocking of iNOS activity by pharmacological agents prevents cytokine-induced ␤-cell dysfunction and death in both rodent and human islets (3). Furthermore, it remains unclear whether the radical NO contributes to cytokine-induced ␤-cell necrosis and/or apoptosis (11)(12)(13). A possible reason for these conflicting observations is the use of relatively nonspecific pharmacological blockers of iNOS activity.…”

Section: Cytokines Induce Apoptosis In ␤-Cellsmentioning

confidence: 89%

Cytokines induce apoptosis in beta-cells isolated from mice lacking the inducible isoform of nitric oxide synthase (iNOS-/-).

et al. 2000

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Prolonged exposure of rodent ␤-cells to combinations of cytokines induces the inducible form of nitric oxide synthase (iNOS) expression and Fas expression, nitric oxide (NO) production, and cell death. It also induces the expression of potential "defense" genes, such as manganese superoxide dismutase (MnSOD) and heat shock protein (hsp) 70. NO is a radical with multifaceted actions. Recent studies have shown that NO, in addition to having cytotoxic actions, may regulate gene transcription. It remains unclear whether NO mediates cytokine-induced gene expression and subsequent ␤-cell death. Previous studies using NO synthase blockers yielded conflicting results, which may be due to nonspecific effects of these agents. In this study, we examined the effects of cytokines on gene expression, determined by reverse transcriptase-polymerase chain reaction (RT-PCR), and viability, determined by nuclear dyes, of pancreatic islets or fluorescence-activated cell sorter (FACS)-purified ␤-cells isolated from iNOS knockout mice (iNOS -/ -, background C57BL/6x129SvEv) or their respective controls (C57BL/6x129SvEv). The combination of cytokines used was interleukin-1␤ (50 U/ml) plus ␥-interferon (1,000 U/ml) plus tumor necrosis factor-␣ (1,000 U/ml). The lack of cytokine-induced iNOS activity in the iNOS -/-islet cells was confirmed by RT-PCR and nitrite determination. Cytokines induced a >3-fold increase in Fas and MnSOD mRNA expression in wild-type (WT) and iNOS -/-islets. On the other hand, hsp 70 was induced in WT but not in iNOS -/-islets. Prolonged (6-9 days) exposure of WT islets to cytokines leads to an 80-90% decrease in islet cell viability, whereas viability decreased by only 10-30% in iNOS -/-islet cells. To determine the mode of cytokine-induced cell death, FACS-purified ␤-cells were exposed to the same cytokines. After 9 days, the apoptosis index was similarly increased in WT (39 ± 3%) and iNOS -/-(33 ± 4%) ␤-cells. On the other hand, cytokines increased necrosis in WT (20 ± 4%) but not in iNOS -/-(7 ± 3%) ␤-cells. From these data, we concluded that 1) NO is required for cytokine-induced hsp 70 mRNA expression but not for Fas and MnSOD expression, 2) cytokines induce both apoptosis and necrosis in mouse ␤-cells, and 3) cytokine-induced apoptosis is mostly NO-independent, whereas necrosis requires NO formation. Diabetes

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“…Excessive levels of NO stimulated by pro-inflammatory cytokine have been shown to mediate cytokine-induced apoptosis and decrease insulin secretion (9,56,57). However, low basal levels of NO play a role in synchronizing glucose-induced [Ca 2ϩ ] i oscillations (58) and regulating insulin secretion (59).…”

Section: Low Levels Of Pro-inflammatory Cytokines Disrupt [Ca 2ϩ ] I mentioning

confidence: 99%

Low Level Pro-inflammatory Cytokines Decrease Connexin36 Gap Junction Coupling in Mouse and Human Islets through Nitric Oxide-mediated Protein Kinase Cδ

Farnsworth

Walter

Hemmati

et al. 2016

Journal of Biological Chemistry

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Pro-inflammatory cytokines contribute to the decline in islet function during the development of diabetes. Cytokines can disrupt insulin secretion and calcium dynamics; however, the mechanisms underlying this are poorly understood. Connexin36 gap junctions coordinate glucose-induced calcium oscillations and pulsatile insulin secretion across the islet. Loss of gap junction coupling disrupts these dynamics, similar to that observed during the development of diabetes. This study investigates the mechanisms by which pro-inflammatory cytokines mediate gap junction coupling. Specifically, as cytokine-induced NO can activate PKC␦, we aimed to understand the role of PKC␦ in modulating cytokine-induced changes in gap junction coupling. Isolated mouse and human islets were treated with varying levels of a cytokine mixture containing TNF-␣, IL-1␤, and IFN-␥. Islet dysfunction was measured by insulin secretion, calcium dynamics, and gap junction coupling. Modulators of PKC␦ and NO were applied to determine their respective roles in modulating gap junction coupling. High levels of cytokines caused cell death and decreased insulin secretion. Low levels of cytokine treatment disrupted calcium dynamics and decreased gap junction coupling, in the absence of disruptions to insulin secretion. Decreases in gap junction coupling were dependent on NO-regulated PKC␦, and altered membrane organization of connexin36. This study defines several mechanisms underlying the disruption to gap junction coupling under conditions associated with the development of diabetes. These mechanisms will allow for greater understanding of islet dysfunction and suggest ways to ameliorate this dysfunction during the development of diabetes.Diabetes is characterized by a progressive decrease in function and mass of ␤-cells, which comprise the majority of cells in the islets of Langerhans (1). Pro-inflammatory cytokines have been implicated as mediators of ␤-cell death in both type 1 diabetes (T1D) 2 and type 2 diabetes (T2D) (2-4). However, pro-inflammatory cytokines also play a role in causing ␤-cell dysfunction early in disease progression (3, 5). In T1D, high levels of pro-inflammatory cytokines, including tumor necrosis factor-␣ (TNF-␣), interleukin-1␤ (IL-1␤), and interferon ␥ (IFN-␥), are released by immune cells, such as CD4 ϩ and CD8 ϩ T-cells and macrophages, which infiltrate the pancreas (3, 6). In T2D, adipocyte stress resulting from obesity can lead to secretion of low levels of circulating TNF-␣ from activated macrophages in adipose tissue; whereas elevated free fatty acids and/or hyperglycemia can also lead to local release of IL-1␤ in the islets (4, 7). Although the mechanisms of cytokine-induced cell death in diabetes are well characterized, cytokine-induced islet dysfunction is poorly understood.In vitro, the pro-inflammatory cytokines TNF-␣, IL-1␤, and IFN-␥ work synergistically (8) to induce islet dysfunction and disrupt insulin secretion (9, 10). The effect of pro-inflammatory cytokines on the ␤-cell is thought to be mediated in part by...

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Apoptotic Cell Death Triggered by Nitric Oxide in Pancreatic β-Cells

Cited by 300 publications

References 23 publications

IFN-γ/TNF-α Synergism as the Final Effector in Autoimmune Diabetes: A Key Role for STAT1/IFN Regulatory Factor-1 Pathway in Pancreatic β Cell Death

IFN-γ/TNF-α Synergism as the Final Effector in Autoimmune Diabetes: A Key Role for STAT1/IFN Regulatory Factor-1 Pathway in Pancreatic β Cell Death

Cytokines induce apoptosis in beta-cells isolated from mice lacking the inducible isoform of nitric oxide synthase (iNOS-/-).

Low Level Pro-inflammatory Cytokines Decrease Connexin36 Gap Junction Coupling in Mouse and Human Islets through Nitric Oxide-mediated Protein Kinase Cδ

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