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Hypoxia and islet inflammation are involved in β-cell failure in type 2 diabetes (T2D). Elevated plasma LPS levels have been verified in patients with T2D, and hypoxia occurs in islets of diabetic mice. Activation of inflammasomes in ischemic or hypoxic conditions was identified in various tissues. Here, we investigated whether hypoxia activates the inflammasome in β cells and the possible mechanisms involved. In mouse insulinoma cell line 6 (MIN6), hypoxia (1% O 2 ) primes the NLRP3 inflammasome along with NF-κB signaling activation. Our results demonstrate that hypoxia can activate the NLRP3 inflammasome in LPS-primed MIN6 to result in initiating the β cell inflammatory response and cell death in vitro. Reactive oxygen species (ROS) and the thioredoxin-interacting protein (TXNIP) are up-regulated in response to hypoxia. Finally, the role of the ROS-TXNIP axis in mediating the activation of the NLRP3 inflammasome and cell death was characterized by pretreating with the ROS scavenger N-acetylcysteine (NAC) and performing TXNIP knockdown experiments in MIN6. Our data indicate for the first time that the inflammasome is involved in the inflammatory response and cell death in hypoxia-induced β cells through the ROS-TXNIP-NLRP3 axis in vitro. This provides new insight into the relationship between hypoxia and inflammation in T2D., (Copyright © 2017 Elsevier Inc. All rights reserved.)

Background: Neonatal pig islet-like cell clusters (NICC) are an attractive source of insulin-producing tissue for potential transplantation treatment of type 1 diabetic patients. However, a considerable loss of NICC after their transplantation due to apoptosis resulted from islet isolation and instant blood-mediated inflammatory reaction remains to be overcome., Methods: EGM2 medium depleted with hydrocortisone and supplemented with 50 mmol/L isobutylmethylxanthine, 10 mmol/L nicotinamide, and 10 mmol/L glucose was used to culture NICC at day 1, the day after isolation and changed every other day. NICC cultured with EGM2 or control Ham's F-10 medium were collected at day 7 of culture for the following assays. The viability of NICC was evaluated by AO/EB staining and FACS. Static assay and oxygen consumption rate analysis were performed to assess the function of NICC. Insulin and glucagon gene expression were measured by real-time PCR. Tubing loops model and TUNEL assay were performed to confirm the apoptosis-resistant ability of NICC cultured with modified EGM2 medium. Serum starvation and hypoxia treatment were used to test the tolerant capability of NICC in the microenvironment of hypoxia/nutrient deficiency in vitro. The molecules involved in apoptosis pathways in NICC were analyzed by Western blotting., Results: Compared with Ham's F-10 medium, culturing NICC with EGM2 medium led to increased number and viability of NICC with higher stimulation index, upregulated gene expression of both insulin and glucagon, and enhanced mitochondria function. Furthermore, fewer modified EGM2 medium cultured NICC were found under apoptosis when evaluated in an in vitro tubing loop model of IBMIR. Moreover, EGM2 medium cultured NICC demonstrated much less apoptotic cells under either serum starvation or hypoxia condition than their Ham's F-10 medium cultured counterparts. The enhanced capability of EGM2 cultured NICC to resist apoptosis was associated with their elevated protein levels of anti-apoptotic Bcl-2 family member Mcl-1., Conclusion: Culturing NICC with EGM2 provides a simple and effective approach not only to increase NICC yield, viability, and maturation but also to enhance their resistance to apoptosis to preserve the initial graft mass for successful islet xenotransplantation., (© 2017 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Background: Since the Fas/Fas Ligand (FasL) interaction is recognized as a major pathway of apoptosis in immune cells, we hypothesized that selective expression of FasL by tubular cells (TC) may promote the resolution of interstitial inflammation by inducing apoptosis of infiltrating immune cells. In this study, the effect of FasL transfection of rat TC on apoptosis of leukocytes was examined., Methods: Rat tubule cells (NRK52E) were transfected with plasmids constructed using human and rat FasL (hFasL and rFasL). The propensity of activated, transfected TC to undergo apoptosis was examined. Similarly, the effects of FasL transfection on apoptosis of Jurkat cells and activated leukocytes were assessed directly following co-culture for 12 hours and in a cell insert system intended to assess the effects of soluble FasL. Fas and FasL expression was assessed by flow cytometry and apoptosis was examined using Annexin V staining and the TUNEL method., Results: Expression of FasL in TC was increased after FasL transfection. Transfected TC showed no detectable increase in apoptosis following lipopolysaccharide (LPS) or tumor necrosis factor-alpha (TNF-alpha) activation. Jurkat cell apoptosis was increased ninefold and eightfold after co-culture with TC transfected with hFasL and rFasL, respectively (67.0 +/- 12.1% and 60.1 +/- 8.8% vs. 6.7 +/- 1.8% with un-transfected TC, P < 0.01). Similarly, apoptosis of activated leukocytes was increased fourfold by co-culture (26.8 +/- 4.9% vs. 6.7 +/- 2.0% with untransfected TC, P < 0.01). Leukocyte apoptosis also was increased in an insert culture system (18.2 +/- 4.4% vs. 5.8 +/- 2.3% with un- transfected TC, P < 0.01). No increase of TC apoptosis was detected in any of the co-culture experiments., Conclusion: Enhanced expression of FasL by TC is capable of inducing apoptosis of activated leukocytes, without evidence for increased susceptibility to apoptosis of the transfected cells themselves. This suggests a potential role for this approach in the limitation and resolution of renal tubulointerstitial inflammation.

Objective: Vascular disease in the umbilical placental circulation that is detected by umbilical artery Doppler study is associated with adverse fetal outcome. Endothelial cell activation and platelet consumption are features of this pathologic condition. We postulated that this was due to the local release of factors that cause endothelial cell injury and that these would spill into the fetal circulation. To test this hypothesis, we examined for the presence in fetal plasma of factors that induced endothelial cell apoptosis in pregnancies that were complicated by umbilical placental vascular disease., Study Design: Isolated and cultured human umbilical vein endothelial cells were exposed to fetal plasma from the 3 fetal groups: normal pregnancy (n = 32 patients), pregnancy with umbilical placental vascular disease that was identified by an abnormal umbilical artery Doppler study (n = 38 patients), and pregnancy with maternal preeclampsia and normal umbilical artery Doppler study (n = 16 patients). Early apoptosis can be recognized by a loss of plasma membrane asymmetry with membrane uptake of annexin V. This was measured with annexin V and propidium iodide staining by fluorescent-activated cell scanning. Cells that underwent early apoptosis stained positive for annexin V and negative for propidium iodide (in contrast with cells that underwent necrosis). Cytosolic proteolytic activity was also measured. The lysates from endothelial cells that were stimulated by fetal plasma from umbilical placental vascular disease were tested for caspase-3 and caspase-8 activities by a fluorescent assay with spectrofluorophotometry., Results: The percentage of endothelial cells that underwent apoptosis was significantly higher (P <.05) when stimulated with fetal plasma from pregnancies with umbilical placental vascular disease (17.71% +/- 1.31%) than with fetal plasma from normal pregnancies (9.76% +/- 0.87%). In the presence of maternal preeclampsia with normal umbilical artery Doppler study, the percent of apoptotic cells (11.31% +/- 1.59%) was similar to that of the normal group. In the group with abnormal umbilical artery Doppler study, there was no difference between pregnancies with preeclampsia (n = 17 pregnancies) and without preeclampsia (n = 21 pregnancies). The protease activity of caspase-3 was significantly enhanced in the group with umbilical placental vascular disease compared with normal pregnancy (0.79 +/- 0.06 vs 0.45 +/- 0.08 microMol/L). However, no difference in caspase-8 activity was detected (0.66 +/- 0.05 vs 0.56 +/- 0.05 microMol/L)., Conclusion: Endothelial cell apoptosis is a feature of umbilical placental vascular disease. Our study demonstrates the presence of factors in the fetal plasma that caused endothelial cells to undergo early apoptosis. This increased apoptosis was only seen in the presence of placental vascular disease and was independent of the presence or absence of maternal preeclampsia. Our results indicate that programmed endothelial cell death occurs in the fetal circulation as a part of the injury that is associated with the development of umbilical placental vascular disease. The caspase-3, rather than caspase-8, signal transduction pathway appears to be involved in the mediation of endothelial cell apoptosis that was detected in our study.

Abstract: Cytokine-induced expression of inducible nitric oxide synthetase (iNOS) and production of nitric oxide (NO) by pancreatic islet cells has been suggested as one potential mechanism for beta cell destruction. In this study, we investigated the role of iNOS and NO in islet primary non-function. Islets were assessed for their function, viability and expression of iNOS. Adult rat and pig islets isolated by collagenase digestion and fetal pig pancreas (FPP) grafts isolated by collagenase digestion or high oxygen culture were transplanted into C57BL6 mice and nude mice. iNOS protein was detected by immunohistochemistry. iNOS protein was found in normal rat and pig pancreas and adult rat and pig islets that were isolated by collagenase digestion and transplanted into either C57BL6 mice or nude mice. iNOS was not detected in fetal pig islet grafts, regardless of whether collagenase was used in the isolation process. In adult pig islet grafts, the presence of iNOS protein correlated with high levels of islet cell apoptosis and primary non-function. Despite the persistent presence of iNOS in rat islets, there was no evidence that it had a deleterious effect on rat islet viability, or function. Therefore, in isolated adult pig islets, there was a correlation between iNOS expression and apoptosis, suggesting that iNOS activation may be deleterious to the adult pig islets. However, other factors such as the fragility of the islet capsule may be equally important. By contrast, fetal pig islets did not express iNOS and this may be an important reason for their enhanced viability when compared with adult islet tissue. [ABSTRACT FROM AUTHOR]