Gα12 and endoplasmic reticulum stress-mediated pyroptosis in a single cycle of dextran sulfate-induced mouse colitis

Inflammatory bowel disease (IBD) pathogenesis involves complex inflammatory events and cell death. Although IBD involves mainly necrosis in the digestive tract, pyroptosis has also been recognized. Nonetheless, the underlying basis is elusive. G alpha 12/13 overexpression may affect endoplasmic reticulum (ER) stress. This study examined how G alpha 12/13 and ER stress affect pyroptosis using dextran sulfate sodium (DSS)-induced colitis models. G alpha 12/13 levels were increased in the distal and proximal colons of mice exposed to a single cycle of DSS, as accompanied by increases of IRE1 alpha, ATF6, and p-PERK. Moreover, Il-6, Il-1 beta, Ym1, and Arg1 mRNA levels were increased with caspase-1 and IL-1 beta activation, supportive of pyroptosis. In the distal colon, RIPK1/3 levels were enhanced to a greater degree, confirming necroptosis. By contrast, the mice subjected to three cycles of DSS treatments showed decreases of G alpha 12/13, as accompanied by IRE1 alpha and ATF6 suppression, but increases of RIPK1/3 and c-Cas3. AZ2 treatment, which inhibited G alpha 12, has an anti-pyroptotic effect against a single cycle of colitis. These results show that a single cycle of DSS-induced colitis may cause ER stress-induced pyroptosis as mediated by G alpha 12 overexpression in addition to necroptosis, but three cycles model induces only necroptosis, and that AZ2 may have an anti-pyroptotic effect.