Statins repress needle-like carbon nanotube- or cholesterol crystal-stimulated IL-1β production by inhibiting the uptake of crystals by macrophages

Statins are 3-hydroxy-3-methylglutaryl-CoA reductase inhibitors that lower atherogenic LDL-cholesterol levels. Statins exert clinically relevant anti-inflammatory effects; however, the underlying molecular mechanism remains unclear. Studies have shown that endogenous and exogenous pathogenic crystals, such as cholesterol and monosodium urate (MSU), and needle-like nanomaterials, such as multi-wall carbon nanotubes (MWCNT), induce the production of IL-1 beta and play a critical role in the development of crystal-associated sterile inflammatory pathologies. In this study, we evaluated the effect of statins on crystal-induced IL-1 beta production in macrophages. We found that various statins, including pitavastatin, atorvastatin, fluvastatin, and lovastatin, but not squalene synthase inhibitor, repressed IL-1 beta release upon MWCNT stimulation. In addition, IL-1 beta production induced by cholesterol crystals and MSU crystals, but not by ATP or nigericin, was diminished. MWCNTstimulated IL-1 beta release was dependent on the expression of NLRP3, but not AIM2, NLRC4, or MEFV. Statininduced repression was accompanied by reduced levels of mature caspase-1 and decreased uptake of MWCNT into cells. Supplementation of mevalonate, geranylgeranyl pyrophosphate, or farnesyl pyrophosphate prevented the reduction in IL-1 beta release, suggesting a crucial role of protein prenylation, but not cholesterol synthesis. The statin-induced repression of MWCNT-elicited IL-1 beta release was observed in THP-1-derived and mouse peritoneal macrophages, but not in bone marrow-derived macrophages where statins act in synergy with lipopolysaccharide to enhance the expression of IL-1 beta precursor protein. In summary, we describe a novel anti-inflammatory mechanism through which statins repress mature IL-1 beta release induced by pathogenic crystals and nanoneedles by inhibiting the internalization of crystals by macrophages.

Automated summary

Studies show that statins can inhibit the production and release of IL-1 beta induced by crystals and nanoneedles by preventing the internalization of crystals by macrophages, thereby exerting anti-inflammatory effects.