MPO and mucositis: Given that anti-inflammatory effects have been reported for CKI, and tissue injury-induced inflammation is one of the hallmarks of the pathobiology of mucositis, the effect of CKI on the extent of radiation-induced epithelial inflammation was also assessed by IHC detection of the tissue damaging proinflammatory enzyme, MPO, and proinflammatory cytokines, IL-1β and IL-6.