Effects of a Low Fat Diet versus a High Fat Diet on Lymphoid Cell Infiltration in a Mouse Model of Oral Cancer

Abstract

IntroductionRisk factors for oral cancer include tobacco use, male sex, and possibly dietary fat. Exposure to 4‐nitroquinoline 1‐oxide (4NQO) in the drinking water causes oral cancer in mice and models the effects of tobacco use. This study was undertaken to investigate the effects of a high saturated fat (HF) or low fat (LF) diet and sex on presence of lymphoid cells in cancerous tongues. We hypothesized that inflammation, characterized by the increased presence of lymphoid cells, would accompany development of tumor lesions and that sex and diet would affect the levels of inflammation.MethodsMale and female C57Bl/6 mice (36 each gender), 5 weeks old, were divided into a low fat (10kcal% fat; LF) or HF (60 kcal% fat) diet. Within each dietary group, mice were randomly assigned to one of 3 water treatment groups for 17 weeks: water alone (control); propylene glycol in water (1.25%; PG‐H2O); or 4NQO in PG‐H2O (50 mg/ml; 4NQO). After 17 weeks, all mice were given water alone for 6 more weeks. Tongues harvested from the euthanized animals were fixed in formalin and processed for histological examination. T cells (CD3+ cells), macrophages (CD68+ cells), and neutrophils (Ly6+ cells) were detected by immunohistochemistry, counted, and normalized to tissue area. Analysis was done using GraphPad Prism 7.0. All animal work was in compliance with the regulations of IACUC at Midwestern University, Downers Grove, IL.ResultsOral cancer developed in all mice exposed to 4NQO and was absent in all controls. All three lymphoid cell types were significantly higher (p<0.05) in the 4NQO mice versus the control mice: CD3+ (11.2 vs 0.9 cells/mm2), CD68+ (3.6 vs 1.5 cells/mm2), and Ly6+ (9.4 vs 0.38 cells/mm2). Among the 4NQO treated mice, there were no significant differences between males and females, or between HF and LF mice for T cells or macrophages. 4NQO treated males had a significantly higher numbers of neutrophils than females (12 vs 6.6 cells/mm2). LF diet increased the levels of neutrophils in both males and females (15 and 7.7 cells/mm2 respectively) when compared to the HF diet in both males and females (9.3 and 5.3 cells/mm2 respectively); however, this trend was not statistically significant. We speculate that the higher carbohydrate content of the LF diet may support increased anaerobic glycolytic metabolism via the Warburg effect.ConclusionDevelopment of 4NQO‐induced oral cancer was accompanied by inflammatory responses as manifested by the presence of T cells, macrophages, and neutrophils. Neutrophils were the only cell type affected by sex and possibly by the content of dietary fat.Support or Funding InformationThis abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.