BackgroundHydrogen sulfide (H2S), produced by the activity of cystathionine-gamma-lyase (CSE), is a key mediator of inflammation in sepsis. The liver sinusoidal endothelial cells (LSECs) are important target and mediator of sepsis. The aim of this study was to investigate the role of CSE-derived H2S on inflammation and LSECs fenestrae in caecal-ligation and puncture (CLP)-induced sepsis using CSE KO mice.MethodsSepsis was induced by CLP, and mice (C57BL/6J, male) were sacrificed after 8 hours. Liver, lung, and blood were collected and processed to measure CSE expression, H2S synthesis, MPO activity, NF-κB p65, ERK1/2, and cytokines/chemokines levels. Diameter, frequency, porosity and gap area of the liver sieve were calculated from scanning electron micrographs of the LSECs.ResultsAn increased CSE expression and H2S synthesizing activity in the liver and lung of wild-type mice following CLP-induced sepsis. This was associated with an increased liver and lung MPO activity, and increased liver and lung and plasma levels of the pro-inflammatory cytokines TNF-α, IL-6, and IL-1β, and the chemokines MCP-1 and MIP-2α. Conversely, CSE KO mice had less liver and lung injury and reduced inflammation following CLP-induced sepsis as evidenced by decreased levels of H2S synthesizing activity, MPO activity, and pro-inflammatory cytokines/chemokines production. Extracellular-regulated kinase (ERK1/2) and nuclear factor-κB p65 (NF-κB) became significantly activated after the CLP in WT mice but not in CSE KO mice. In addition, CLP-induced damage to the LSECs, as indicated by increased defenestration and gaps formation in the LSECs compared to WT sham control. CSE KO mice showed decreased defenestration and gaps formation following sepsis.ConclusionsMice with CSE (an H2S synthesising enzyme) gene deletion are less susceptible to CLP-induced sepsis and associated inflammatory response through ERK1/2-NF-κB p65 pathway as evidenced by reduced inflammation, tissue damage, and LSECs defenestration and gaps formation.

How controversies regarding hydrogen sulfide may have occurred is discussed. Addressed are the direct and indirect pathways of hydrogen sulfide on inflammation, the effects of different concentrations of hydrogen sulfide and how the effects of hydrogen sulfide on the immune system vary with different delivery mechanisms. Furthermore, there is a discussion on what key gaps exist in current knowledge and must be addressed before hydrogen sulfide can be considered a valid pharmacological target.

Hydrogen sulfide (H2S) is an endogenous inflammatory mediator produced by the activity of cystathionine γ-lyase (CSE) in mammals. Macrophages are a key element of the immune system and play a crucial role in inflammation. To determine the role of H2S and macrophages in inflammation, we investigated the expression of CSE in human primary macrophages. Our results show that H2S is produced by the activity of CSE in these cells. To investigate the role of common signalling pathway in biosynthesis of CSE in human primary macrophages, specific inhibitors were used to block NF-κB, ERK, p38 and JNK. Inhibition of NF-κB, ERK significantly reduced levels of CSE gene and protein expression in these cells but inhibition of JNK and p38 did not have an inhibitory effect on the expression of CSE gene in macrophages. Inhibition of NF-κB and ERK prevented the effect of LPS on H2S synthesizing activity in human primary macrophages. These data showed that H2S acts as an inflammatory mediator via NF-κB/ERK pathway in macrophages.

The purpose of this study was to compare the specific activity of proteinase A in Candida albicans (C. albicans) between multiple sclerosis (MS) patients and controls. A total of 135 and 100 C. albicans strains were isolated from superficial surfaces of MS patients and healthy controls. Analytical models (regression and neural network) were applied to predict the severity of MS considering specific enzyme activity (SEA) and other factors which affect the expanded disability status scale (EDSS). The SEA of C. albicans in MS patients (3466.95 ± 277.25 μmol min mg ) was significantly more than that of healthy controls (1108.98 ± 294.51 μmol min mg ) that was confirmed by regression model (P < 0.001). The SEA had a positive correlation with the severity of MS (P < 0.001, r = 0.65). Analytical models showed that SEA played the most important role (among all included factors that affect on EDSS) in the severity of MS. The SEA of C. albicans in MS patients was significantly more than the healthy controls. The results suggest that the level of SEA of proteinase A and probably the capacity of C. albicans isolates to invade the host tissue is associated with the severity of MS.