Immune control of experimental melanoma B-16 during nutrient restriction in organsand tissues of C57Bl6 mice

Abstract

The results of multicenter international clinical trials have shown that calorie restriction is a dietary regimen that helps to slow the progression of a number of pathologies. The influence of diet on melanoma development is a promising research area; however, the molecular aspects of cutaneous melanoma, and in particular, immune control during experimental calorie restriction, have not been adequately studied. The objective of the study was to identify the effects of a restrictive diet on the percentage of CD4- and CD8-expressing cells in the organs of C57Bl6 mice developing experimental B-16 melanoma.
Materials and Methods: Control groups included intact animals maintained on either a basal diet (ad libitum feeding) or a 30% calorie-restricted diet. Experimental groups included animals with experimental B-16 melanoma, either fed ad libitum or with 30% calorie restriction. On day 15 of tumor development, tissue samples from various organs were collected. Immunofluorescence analysis was performed on lung, kidney, and liver tissue samples from all animal groups, as well as tumor nodule tissue from mice with experimental B-16 melanoma.
Results: Differences in average animal weight were observed between the control and experimental groups, as well as a decrease in tumor volume in the calorie-restricted diet group compared to the basal diet group. The calorie-restricted diet resulted in an increase in the percentage of helper T lymphocytes (CD4), T-regulatory lymphocytes, and/or cytotoxic T cells (CD8) in the tumor microenvironment, possibly due to activation of autophagy or microautophagy (mitophagy).
Conclusions: A calorie-restricted diet inhibits tumor growth and alters the microenvironmental cell structure (increased percentages of CD4- and CD8-positive cells in tumor tissue and analyzed lung, liver, and kidney tissues). Thus, calorie restriction modulates the activity of immune antitumor defense, which may provide a pathogenetic basis for effective adjuvant treatments for malignant neoplasms.