Hydrogen sulfide primes diabetic wound to close through inhibition of NETosis.

Diabetes-induced neutrophil NETosis impairs wound healing through neutrophil extracellular traps (NETs). Reactive oxygen species (ROS)-triggered activation of mitogen-activated protein kinase (MAPK) ERK1/2 and p38 is involved in NETosis. Hydrogen sulfide (H2S), an endogenous signaling molecule, accelerates diabetic wound healing (DWH), and inhibits ROS production, ERK1/2 and p38 activation, while its level is decreased in diabetes. However, it remains unknown whether H2S could accelerate DWH through inhibition of NETosis, and whether this inhibitory effect was associated with blockage of ROS-induced ERK1/2 and p38 activation. In order to solve these problems, serum NETs content was measured in diabetic foot patients and healthy individuals. Wound was created in dorsal skin of LepRdb/db and control mice and NETs content in wound tissues was tested. An in vitro NETosis model was induced by phorbol 12-myristate 13-acetate (PMA) in isolated neutrophils. Effects of H2S in form of Na2S on skin wound healing and NETosis were investigated both in vivo and in vitro. It was found that NETs level was highly increased in diabetic foot patients. Comparing with LepRm+/db mice, DWH was delayed in LepRdb/db mice, accompanied with high NETs level. In PMA-induced NETosis model, peptidylarginine deiminase (PAD)-4 and citrullinated histone H3, as well as NETs components dsDNA framework, myeloperoxidase and neutrophil elastase, were significantly increased. PMA-induced neutrophil NETosis and NETs formation were abolished by treatment with H2S. The delayed DWH of diabetic mice was partially restored by intraperitoneal injection of H2S, meanwhile, the highly expressed NETosis and NETs release were also down-regulated. The treatment with H2S not only attenuated ROS production but also abolished MAPK ERK1/2 and p38 activation. Like the effects of H2S, inhibition of MAPK ERK1/2 or p38 could decrease NETs release. These findings suggests that H2S attenuates NETosis and primes diabetic wound to heal through blockage of ROS-mediated MAPK ERK1/2 and p38 activation.

[Interaction between glycogen synthase kinase-3ß and endoplasmic reticulum stress is involved in high glucose-induced injury in human umbilical vein endothelial cells].

OBJECTIVE: To explore the role of the interaction between glycogen synthase kinase-3ß (GSK-3ß) and endoplasmic reticulum stress (ERS) in the high glucose (HG)-induced injury in human umbilical vein endothelial cells (HUVECs). METHODS: HUVECs treated with 40 mmol/L glucose for 24 h were examined for expression levels of GSK-3ß, GRP78, CHOP and cleaved caspase-3 protein using Western blotting. The cell viability was examined using CCK-8 assay and cell apoptosis was detected with Hoechst 33258 nuclear staining and photofluorography. The intracellular level of reactive oxygen species (ROS) was measured with dichlorfluoresein staining and photofluorography. Mitochondrial membrane potential (MMP) was tested by rhodamine 123 (Rh123) staining and photofluorography. RESULTS: Treatment of HUVECs with 40 µmol/L glucose for 3-24 h activated GSK-3ß in a time-dependent manner, leading to significantly down-regulated expression of phosphorylated (p)-GSK-3ß (P<0.05). HG exposure of the cells for 1-24 h induced ERS, evidenced by time-dependently up-regulated expression of GRP78 and CHOP (P<0.05). LiCl, an inhibitor of GSK-3ß, attenuated HG-induced ERS and significantly lowered the expression levels of GRP78 and CHOP (P<0.01). 4-PBA, an inhibitor of ERS, obviously ameliorated the activation of GSK-3ß by HG as shown by the increase in p-GSK-3ß expression level (P<0.01). HG exposure for 24 h induced obvious injuries in HUVECs, which exhibited decreased cell viability, increased cell apoptosis, increased expression of cleaved caspase-3 and ROS generation, and loss of MMP. Pretreatment of the cells with LiCl or 4-PBA for 60 min before HG exposure significantly lessened the cell injuries (P<0.01). CONCLUSION: Interactions between GSK-3ß and ERS occur in HUVECs exposed to HG and participate in HG-induced cell injuries.

[Angiotensin-(1-7) protects cardiac myocytes against high glucose-induced injury by inhibiting ClC-3 chloride channels].

OBJECTIVE: To explore whether angiotensin-(1-7) [Ang-(1-7)] protects cardiac myocytes against high glucose (HG)-induced injury by inhibiting ClC-3 chloride channels. METHOD: H9c2 cardiac cells were exposed to 35 mmol/L glucose for 24 h to establish a cell injury model. The cells were treated with Ang-(1-7) or the inhibitor of chloride channel (NPPB) in the presence of HG for 24 h to observe the changes in HG-induced cell injury. Cell counter kit 8 (CCK-8) assay was used to test the cell viability, and the morphological changes of the apoptotic cells were detected using Hoechst 33258 staining and fluorescent microscopy. The intracellular level of reactive oxygen species (ROS) was examined by DCFH-DA staining, SOD activity in the culture medium was measured using commercial kits, and the mitochondrial membrane potential (MMP) of the cells was tested with rodamine 123 staining. The expression level of cardiac ClC-3 chloride channels was detected with Western blotting. RESULTS: Exposure of H9c2 cardiac cells to 35 mmol/L glucose for 24 h markedly enhanced the expressions of cardiac ClC-3 channel protein (P<0.01). Co-treatment of the cells with 1 µmol/L Ang-(1-7) and HG for 24 h significantly attenuated HG- induced upregulation of ClC-3 channel protein expression (P<0.01). Co-treatment of the cells exposed to HG with 1 µmol/L Ang-(1-7) or 100 µmol/L NPPB for 24 h obviously ameliorated HG-induced injuries as shown by increased cell viability, enhanced SOD activity, decreased number of apoptotic cells, and reduced intracellular ROS generation and loss of MMP (P<0.01). CONCLUSION: ClC-3 channels are involved in HG-induced injury in cardiac cells. Ang-(1-7) protects cardiac cells against HG-induced injury by inhibiting ClC-3 channels.