A variety of stimuli, including
monosodium urate (MSU) crystals, activate the NLRP3
inflammasome, and this activation involves several molecular mechanisms including
xanthine oxidase (XO) up-regulation and
mitochondrial dysfunction. Upon oligomerization of apoptosis-associated speck-like
protein containing a CARD (ASC), caspase-1 becomes active and cleaves the proinflammatory
cytokine IL-1β into its active secreted form.
Hydrogen sulfide (H2S), a
gasotransmitter mainly produced by
cystathionine γ-
lyase (CSE) in macrophages, could modulate
inflammation. Here, we sought to investigate the effects of exogenous and endogenous H2S on NLRP3
inflammasome activation in vitro and in vivo Primed bone marrow-derived macrophages (BMDM) isolated from wildtype (wt) or CSE-deficient mice and human macrophages (THP1 cells and primary macrophages), were stimulated with MSU crystals in the presence or absence of a H2S donor,
sodium thiosulfate (STS) or
GYY4137 (GYY). In murine and human macrophages in vitro, both STS and GYY inhibited MSU crystal-induced IL-1β secretion in a dose-dependent manner. Moreover, the H2S donors inhibited MSU crystal-induced XO/
caspase-1 activities, mitochondrial
reactive oxygen species (ROS) generation, and ASC oligomerization. Accordingly, IL-1β secretion and XO/
caspase-1 activities were higher in CSE-deficient BMDMs than in wt BMDMs. For in vivo studies, we experimentally induced
peritonitis by
intraperitoneal injection of MSU crystals into mice. GYY pretreatment ameliorated
inflammation, evidenced by decreased IL-6/
monocyte chemoattractant protein-1 (MCP-1) released into peritoneal lavages. Taken together, our results suggest that both exogenous (via H2S donors) and endogenous (via CSE) H2S production may represent approaches for managing, for example, acute
gout or other
inflammation conditions.