Colorectal cancer (CRC) is the third most common cancer worldwide and the second leading cause of cancer death in the United States. Cytotoxic therapies cause significant side effects for most patients and do not offer cure in many advanced cases of CRC. Immunotherapies are a promising new approach to harness the body’s own immune system and inflammatory response to attack and clear the cancer. Tryptophan metabolism along the kynurenine pathway is a particularly promising target for immunotherapy. Indoleamine 2,3 dioxygenase 1 (IDO1) is the most well studied of the enzymes that initiate this pathway and it is commonly overexpressed in CRC. Herein, we provide an in-depth review of how tryptophan metabolism and kynurenine pathway metabolites shape factors important to CRC pathogenesis including the host mucosal immune system, pivotal transcriptional pathways of neoplastic growth and luminal microbiota. This pathway’s role in other gastrointestinal malignancies such as gastric, pancreatic, esophageal and gastrointestinal stromal tumors (GIST) is also discussed. Finally, we highlight how currently available small molecule inhibitors and emerging methods for therapeutic targeting of IDO1 might be applied to colon, rectal and colitis associated cancer.

Reduction in Complex II activity appears to be a specific change in UC, present in quiescent and active disease. Mitochondrial complex dysfunction occurs in DSS colitis in mice and appears to be mediated by nitric oxide.

We evaluated a monoclonal antibody-based enzyme immunoassay for detecting soluble parasite antigen in sera collected in an area in South India endemic for Wuchereria bancrofti. Filarial antigen was detected in sera from 56 of 57 microfilaremic patients, 9 of 64 aminofilaremic patients with clinical filariasis, and 11 of 70 endemic controls. Antigen was not detected in sera from patients from nonendemic areas who had a variety of other filarial and nonfilarial helminth infections. Parasite antigen titers were significantly correlated with microfilarial counts in night blood smears (r = .64, P less than .01). Negative antigen tests in patients with clinical filariasis may be explained in part by antibody-mediated clearance of circulating antigen. Antibodies to circulating W. bancrofti antigen were detected in 41 of 55 antigen-negative sera from patients with clinical filariasis. Despite this limitation, detecting parasite antigen by enzyme immunoassay provides significant advantages over previously available methods for diagnosing active W. bancrofti infection.

A defect of mitochondrial acetoacetyl CoA thiolase occurs in ulcerative colitis. Increased reactive oxygen species generation in mitochondria of epithelial cells in ulcerative colitis may underlie this defect.