The roles of autophagy and the inflammasome during environmental stress-triggered skin inflammation

Inflammatory skin diseases are the most common problem in dermatology. The induction of skin inflammation by environmental stressors such as ultraviolet radiation (UVR), hexavalent chromium (Cr(VI)) and TiO₂/ZnO/Ag nanoparticles (NPs) has been demonstrated previously. Recent studies have indicated that the inflammasome is often wrongly activated by these environmental irritants, thus inducing massive inflammation and resulting in the development of inflammatory diseases. The regulation of the inflammasome with respect to skin inflammation is complex and is still not completely understood. Autophagy, an intracellular degradation system that is associated with the maintenance of cellular homeostasis, plays a key role in inflammasome inactivation. As a housekeeping pathway, cells utilize autophagy to maintain the homeostasis of the organ structure and function when exposed to environmental stressors. However, only a few studies have examined the effect of autophagy and/or the inflammasome on skin pathogenesis. Here we review recent findings regarding the involvement of autophagy and inflammasome activation during skin inflammation. We posit that autophagy induction is a novel mechanism inter-modulating environmental stressor-induced skin inflammation. We also attempt to highlight the role of the inflammasome and the possible underlying mechanisms and pathways reflecting the pathogenesis of skin inflammation induced by UVR, Cr(VI) and TiO₂/ZnO/Ag NPs. A more profound understanding about the crosstalk between autophagy and the inflammasome will contribute to the development of prevention and intervention strategies against human skin disease.