Prostaglandin E2 promotes survival of naive UCB T cells via the Wnt/ß-catenin pathway and alters immune reconstitution after UCBT.

The outcome of umbilical cord blood transplantation (UCBT) is compromised by low hematopoietic stem cell (HSC) doses leading to prolonged time to engraftment, delayed immunological reconstitution and late memory T-cell skewing. Exposure of UCB to dimethyl-prostaglandin E2 (dmPGE2) increases HSC in vivo. We determined that exposure of UCB T lymphocytes to dmPGE2 modified Wnt signaling resulting in T cell factor (TCF)-mediated transcription. Wnt signaling upregulated interleukin (IL)-7R and IL-2Rß, resulting in enhanced survival mediated by the homeostatic cytokines IL-7 and IL-15. dmPGE2 also induced components of the Wnt pathway and Wnt receptors, thereby priming UCB T cells to receive signals via Wnt ligands in vivo. We observed that the Wnt transcription factor TCF7 and its target EOMES were elevated in the T cells of patients who received PGE2-treated UCBs. Consistent with the role of Wnt/ß-catenin signaling to induce and maintain naive, memory precursors and long-lived central memory CD8(+) cells, these patients also had increased fractions of CD8(+)CD45RO(-)CD62L(+) plus CD8(+)CD45RO(+)CD62L(+) subsets encompassing these T-cell populations. These effects of the PGE2/Wnt/ß-catenin axis may have significant implications for harnessing immunity in the context of UCBT, where impaired immune reconstitution is associated with late memory T-cell skewing.

Thiol redox state and oxidative stress affect sclerotial differentiation of the phytopathogenic fungi Sclerotium rolfsii and Sclerotinia sclerotiorum.

AIMS: To investigate the involvement of oxidative stress and thiol redox state (TRS) in sclerotial differentiation of Sclerotium rolfsii and Sclerotinia sclerotiorum. METHODS AND RESULTS: Oxidative stress in these fungi was assessed by lipid peroxidation, which was higher in comparison with their nonsclerotiogenic counterpart strains. TRS [measured as glutathione (GSH) and cysteine] was associated with oxidative stress and differentiation using the TRS modulator and antioxidant Nu-acetylcysteine (AcCSH) and the GSH biosynthesis inducer and inhibitor l-2-oxo-thiazolidine-4-carboxylate and L-buthionine-S,R-sulphoximine (BSO) respectively. Differentiation and oxidative stress was decreased by AcCSH in both fungi. The decrease of differentiation by BSO was not associated with oxidative stress in these fungi. CONCLUSIONS: Differentiation and oxidative stress in both fungi depends on the availability of antioxidant noncytotoxic -SH groups and is not depended on any direct antioxidant role of GSH and its precursor cysteine. SIGNIFICANCE AND IMPACT OF THE STUDY: This study helps to understand the mechanism(s) of sclerotial differentiation in these agriculturally important phytopathogenic fungi and proposes that AcCSH can be used as potent fungicide by (i) acting as growth inhibiting cytotoxic oxidant and (ii) sustaining these fungi in their undifferentiated hyphal stage where they are vulnerable to degradation by soil micro-organisms.

Evidence for oxidative stress in lens epithelial cells in pseudoexfoliation syndrome.

PURPOSE: To investigate the oxidative status in lens epithelial cells of patients with pseudoexfoliation (PEX) syndrome. METHODS: Lens capsule samples obtained during cataract surgery of patients with PEX syndrome and normal age-matched control subjects were examined for changes in the levels of glutathione (GSH), glutathione disulphide (GSSG), protein concentration, and lipid peroxidation. Concentrations of GSH, GSSG, lipid peroxidation, and protein concentration were determined by specific fluorescent assays. RESULTS: This study shows a 2.2- and 2.0-fold decrease in GSH and GSSG levels, respectively, in PEX lens epithelial lens compared with non-PEX lens epithelial cells, as well as a 2.5-fold increase in lipid peroxidation product malondialdehyde (MDA) levels. CONCLUSION: The increased MDA and decreased GSH levels indicate high oxidative stress. On the other hand, GSSG usually increases in cases of high-oxidative stress, but this is not always the case, as it may not always accumulate in cells. Our findings suggest a role for oxidative stress in the pathogenesis and the progression of PEX syndrome.

Evidence for intestinal oxidative stress in patients with obstructive jaundice.

BACKGROUND: Obstructive jaundice results in failure of the intestinal barrier with consequent systemic endotoxemia associated with septic complications. We have recently shown that gut barrier failure in experimental obstructive jaundice is associated with high intestinal oxidative stress. This study was undertaken to investigate whether oxidative alterations occur in the intestinal mucosa of patients with obstructive jaundice. PATIENTS AND METHODS: Fifteen patients with malignant biliary obstruction and no signs of cholangitis and 15 control patients were subjected to duodenal biopsy to assess intestinal oxidative stress, estimated by lipid peroxidation (malondialdehyde - MDA) and glutathione redox state [reduced glutathione (GSH), glutathione disulphide (GSSG) and GSH/GSSG ratio]. In addition, mucosal biopsies were examined histologically and intestinal mucosal protein content was determined biochemically as an index of intestinal trophic state. RESULTS: Patients with obstructive jaundice presented high levels of intestinal oxidative stress, with significantly increased lipid peroxidation (P < 0.001). Glutathione redox state was also suggestive of high intestinal oxidative stress in jaundiced patients, indicated by significantly decreased GSH (P = 0.001) and GSH/GSSG ratio (P = 0.006) and increased GSSG (P = 0.026). Histological examination showed a mild infiltration of the lamina propria by chronic inflammatory cells in obstructive jaundice, whereas duodenal architecture remained intact and epithelial continuity was retained. Duodenal mucosa was atrophic in jaundiced patients as indicated by a significant reduction of mucosal protein content compared with controls (P = 0.001). Among oxidative stress parameters, intestinal GSH exhibited a significant positive correlation with mucosal protein content (r = 0.588, P = 0.021). CONCLUSIONS: Obstructive jaundice in humans induces intestinal oxidative stress, which may be a key factor contributing to intestinal barrier failure and the development of septic complications in this patient population.

Glutathione and lipid peroxide changes in pseudoexfoliation syndrome.

PURPOSE: To investigate the oxidative status of the aqueous humor of patients with pseudoexfoliation (PEX) syndrome. METHODS: Aqueous humor samples obtained during cataract surgery of patients with PEX syndrome and normal age-matched control subjects were examined for changes in the levels of glutathione (GSH), glutathione disulfide (GSSG), and TBA reactive species (TBARS), products of lipid peroxidation. GSH, GSSG, and TBARS were determined by specific fluorescent assays. RESULTS: Compared to normal controls, PEX syndrome aqueous humor samples showed a decrease of up to 28% of GSH concentration, and GSSG was increased up to 23%. The ratio of GSH/GSSG was 1.7-fold decreased in PEX syndrome samples. TBARS levels were increased by 100% in the PEX aqueous humor samples as compared to the controls. CONCLUSIONS: High levels of GSSG and TBARS indicate high oxidative stress, as well as the decrease in the ratio of GSH/GSSG. Our findings suggest a role for oxidation stress in the pathogenesis and the progression of PEX syndrome.

Evidence for intestinal oxidative stress in obstructive jaundice-induced gut barrier dysfunction in rats.

AIM: An important factor that promotes bacterial and endotoxin translocation in obstructive jaundice is intestinal injury that causes increased permeability. However, little is known of the submicroscopic biochemical events leading to defects of the intestinal barrier. This study was undertaken to investigate the effect of experimental obstructive jaundice on intestinal lipid peroxidation, protein oxidation and thiol redox state. METHODS: Rats were randomly divided into controls, sham operated and bile duct ligated (BDL). After 10 days, intestinal barrier function was assessed by measuring endotoxin in portal and aortic blood. Tissue samples from the terminal ileum were examined histologically and morphometrically, while other samples were homogenized for the determination of lipid peroxidation, protein oxidation and thiol redox state [reduced glutathione (GSH), oxidized glutathione (GSSG), total non-protein mixed disulphides (NPSSR), protein thiols (PSH) and protein disulphides (PSSP)]. RESULTS: Obstructive jaundice compromised intestinal barrier function leading to significant portal and systemic endotoxaemia. The intestinal mucosa in jaundiced rats was atrophic with significantly decreased villous density and total mucosal thickness. Determination of biochemical parameters of oxidative stress in the intestine showed increased lipid peroxidation and protein oxidation in BDL-rats. Thiol redox state revealed the presence of intestinal oxidative stress in jaundiced rats, indicated by a decrease in GSH and increased GSSG, NPSSR and PSSP. CONCLUSIONS: This study shows that experimental obstructive jaundice induces intestinal oxidative stress, which may be a key factor contributing to intestinal injury and leading to endotoxin translocation.