Hydrogen sulfide inhibits calcification of heart valves; implications for calcific aortic valve disease

This is the final version. Available from the publisher via the DOI in this record.Background and Purpose: Calcification of heart valves is a frequent pathological finding in chronic kidney disease and in elderly patients. Hydrogen sulfide (H2S) may exert anti-calcific actions. Here we investigated H2S as an inhibitor of valvular calcification and to identify its targets in the pathogenesis. Experimental Approach: Effects of H2S on osteoblastic transdifferentiation of valvular interstitial cells (VIC) isolated from samples of human aortic valves were studied using immunohistochemistry and western blots. We also assessed H2S on valvular calcification in apolipoprotein E-deficient (ApoE−/−) mice. Key Results: In human VIC, H2S from donor compounds (NaSH, Na2S, GYY4137, AP67, and AP72) inhibited mineralization/osteoblastic transdifferentiation, dose-dependently in response to phosphate. Accumulation of calcium in the extracellular matrix and expression of osteocalcin and alkaline phosphatase was also inhibited. RUNX2 was not translocated to the nucleus and phosphate uptake was decreased. Pyrophosphate generation was increased via up-regulating ENPP2 and ANK1. Lowering endogenous production of H2S by concomitant silencing of cystathionine γ-lyase (CSE) and cystathionine β-synthase (CBS) favoured VIC calcification. analysis of human specimens revealed higher Expression of CSE in aorta stenosis valves with calcification (AS) was higher than in valves of aortic insufficiency (AI). In contrast, tissue H2S generation was lower in AS valves compared to AI valves. Valvular calcification in ApoE−/− mice on a high-fat diet was inhibited by H2S. Conclusions and Implications: The endogenous CSE-CBS/H2S system exerts anti-calcification effects in heart valves providing a novel therapeutic approach to prevent hardening of valves

Hydrogen sulfide as an anti-calcification stratagem in human aortic valve: Altered biogenesis and mitochondrial metabolism of H2S lead to H2S deficiency in calcific aortic valve disease.

This is the final version. Available from Elsevier via the DOI in this record. Data availability: No data was used for the research described in the article.Hydrogen sulfide (H2S) was previously revealed to inhibit osteoblastic differentiation of valvular interstitial cells (VICs), a pathological feature in calcific aortic valve disease (CAVD). This study aimed to explore the metabolic control of H2S levels in human aortic valves. Lower levels of bioavailable H2S and higher levels of interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) were detected in aortic valves of CAVD patients compared to healthy individuals, accompanied by higher expression of cystathionine γ-lyase (CSE) and same expression of cystathionine β-synthase (CBS). Increased biogenesis of H2S by CSE was found in the aortic valves of CAVD patients which is supported by increased production of lanthionine. In accordance, healthy human aortic VICs mimic human pathology under calcifying conditions, as elevated CSE expression is associated with low levels of H2S. The expression of mitochondrial enzymes involved in H2S catabolism including sulfide quinone oxidoreductase (SQR), the key enzyme in mitochondrial H2S oxidation, persulfide dioxygenase (ETHE1), sulfite oxidase (SO) and thiosulfate sulfurtransferase (TST) were up-regulated in calcific aortic valve tissues, and a similar expression pattern was observed in response to high phosphate levels in VICs. AP39, a mitochondria-targeting H2S donor, rescued VICs from an osteoblastic phenotype switch and reduced the expression of IL-1β and TNF-α in VICs. Both pro-inflammatory cytokines aggravated calcification and osteoblastic differentiation of VICs derived from the calcific aortic valves. In contrast, IL-1β and TNF-α provided an early and transient inhibition of VICs calcification and osteoblastic differentiation in healthy cells and that effect was lost as H2S levels decreased. The benefit was mediated via CSE induction and H2S generation. We conclude that decreased levels of bioavailable H2S in human calcific aortic valves result from an increased H2S metabolism that facilitates the development of CAVD. CSE/H2S represent a pathway that reverses the action of calcifying stimuli.Eotvos Lorand Research NetworkHungarian GovernmentEuropean Union and the European Social FundEuropean Union and the European Social FundMinistry of Innovation and Technology of Hungary from the National Research, Development and Innovation FundMinistry of Innovation and Technology of Hungary from the National Research, Development and Innovation Fun