TNFR1 Deficiency Protects Mice from Colitis-Associated Colorectal Cancer Coupled with a Decreased Level of Oxidative Damage in the Colon: Implications for Anti-TNF Therapy of Unremitting Colitis
Bibliographic record
Abstract
It has long been appreciated that there is a direct relationship between the intensity and duration of inflammatory bowel diseases (IBD) and increasing intestinal cancer risk but which elements of the inflammatory response are responsible have not been identified. Anti-TNF drugs have been successful at treating IBD but considering the presumed anti-tumor activity of TNF, it is important to understand whether the treatment impacts on the patients’ intestinal cancer risk. We modeled this relationship by “treating mice lacking TNF receptors with a colon cancer causing combination of azoxymethane followed by repeated dextran sulphate sodium exposures (AOM + DSS regime). TNF receptor type1 gene deficient (TNFR1-/-) and TNFR2-/- mice experienced similar clinical illnesses and colonic inflammation as C57BL/6 wildtype controls during the AOM + DSS regime. Despite the inflammation, TNFR1-/- mice developed significantly fewer colon tumors than the other strains. The reduced tumor incidence was a product of the combined lack of receptor expression on hematopoietic and nonhematopoietic cells, shown using bone marrow cell chimeras of wildtype and TNFR1-/- mice. As oxidative damage is a potent contributing factor to tumorigenesis and inflammatory leukocytes make copious amounts of reactive oxygen radicals, we measured oxidative damage in the animals’ colons. TNFR1-/- mice showed less damage compared to the other strains. We subsequently examined mice deficient in their leukocyte NADPH oxidative pathway (Nox2-/-) for their cancer incidence using the AOM + DSS regime. Nox2-/- mice became inflamed but had fewer tumors than wildtype mice. We conclude that TNF promotes colon cancer including through promoting oxidative processes utilizing TNFR1 in leukocytes. Moreover, the C57BL/6 strain can be used to dissociate mechanisms of colon inflammation from tumorigenic processes. We interpret our results to mean that IBD patients on TNF antagonist therapies will potentially benefit with reduced colon cancer risk even if they do not respond with reduced inflammation.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.002 |
| Insufficient payload (model declined to judge) | 0.002 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".