Cellular sources of pathogenic and protective TNF and experimental strategies based on utilization of TNF humanized mice.

Over the years, tumor necrosis factor (TNF) has been implicated in the pathogenesis of various inflammatory conditions and TNF antagonists are highly efficient in treatment of multiple autoimmune diseases. However, it has been shown that various cellular sources of TNF exhibit distinct and non-redundant functions that can be either deleterious or beneficial. This suggests that systemic TNF blockade, in addition to neutralization of pathogenic TNF, may abrogate its protective functions, resulting in adverse effects.

IL-13 but not IL-4 signaling via IL-4Rα protects mice from papilloma formation during DMBA/TPA two-step skin carcinogenesis.

Interleukin 4 (IL-4) was shown to be tumor-promoting in full carcinogenesis studies using 3-methylcholanthrene (MCA). Because heretofore the role of IL-4 in DMBA/TPA (9,10-dimethyl-1,2-benz-anthracene/12-O-tetradecanoylphorbol-13-acetate) two-stage carcinogenesis was not studied, we performed such experiments using either IL-4(-/-) or IL-4Rα(-/-) mice. We found that IL-4Rα(-/-) but not IL-4(-/-) mice have enhanced papilloma formation, suggesting that IL-13 may be involved.