Biphasic inflammatory response induced by intra-plantar injection of L-cysteine: Role of CBS-derived H2S and S1P/NO signaling

Hydrogen sulfide dysfunction in metabolic syndrome-associated vascular complications involves cGMP regulation through soluble guanylyl cyclase persulfidation

Here, by using in vitro and ex vivo approaches, we elucidate the impairment of the hydrogen sulfide (H2S) pathway in vascular complications associated with metabolic syndrome (MetS). In the in vitro model simulating hyperlipidemic/hyperglycemic conditions, we observe significant hallmarks of endothelial dysfunction, including eNOS/NO signaling impairment, ROS overproduction, and a reduction in CSE-derived H2S. Transitioning to an ex vivo model using db/db mice, a genetic MetS model, we identify a downregulation of CBS and CSE expression in aorta, coupled with a diminished L-cysteine-induced vasorelaxation. Molecular mechanisms of eNOS/NO signaling impairment, dissected using pharmacological and molecular approaches, indicate an altered eNOS/Cav-1 ratio, along with reduced Ach- and Iso-induced vasorelaxation and increased L-NIO-induced contraction. In vivo treatment with the H2S donor Erucin ameliorates vascular dysfunction observed in db/db mice without impacting eNOS, further highlighting a specific action on smooth muscle component rather than the endothelium. Analyzing the NO signaling pathway in db/db mice aortas, reduced cGMP levels were detected, implicating a defective sGC/cGMP signaling. In vivo Erucin administration restores cGMP content. This beneficial effect involves an increased sGC activity, due to enzyme persulfidation observed in sGC overexpressed cells, coupled with PDE5 inhibition. In conclusion, our study demonstrates a pivotal role of reduced cGMP levels in impaired vasorelaxation in a murine model of MetS involving an impairment of both H2S and NO signaling. Exogenous H2S supplementation through Erucin represents a promising alternative in MetS therapy, targeting smooth muscle cells and supporting the importance of lifestyle and nutrition in managing MetS.

Searching for Novel Sources of Hydrogen Sulfide Donors: Chemical Profiling of Polycarpa aurata Extract and Evaluation of the Anti-Inflammatory Effects

Hydrogen sulfide (H2S) is a signaling molecule endogenously produced within mammals' cells that plays an important role in inflammation, exerting anti-inflammatory effects. In this view, the research has shown a growing interest in identifying natural H2S donors. Herein, for the first time, the potential of marine extract as a source of H2S-releasing agents has been explored. Different fractions obtained by the Indonesian ascidian Polycarpa aurata were evaluated for their ability to release H2S in solution. The main components of the most active fraction were then characterized by liquid chromatography-high-resolution mass spectrometry (LC-HRMS) and NMR spectroscopy. The ability of this fraction to release H2S was evaluated in a cell-free assay and J774 macrophages by a fluorimetric method, and its anti-inflammatory activity was evaluated in vitro and in vivo by using carrageenan-induced mouse paw edema. The anti-inflammatory effects were assessed by inhibiting the expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX2), and interleukin-6 (IL-6), coupled with a reduction in nitric oxide (NO) and IL-6 levels. Thus, this study defines the first example of a marine source able to inhibit inflammatory responses in vivo through the release of H2S.