1. Proteobacteria impair anti-tumor immunity in the omentum by consuming arginine.
- Author
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Meza-Perez S, Liu M, Silva-Sanchez A, Morrow CD, Eipers PG, Lefkowitz EJ, Ptacek T, Scharer CD, Rosenberg AF, Hill DD, Arend RC, Gray MJ, and Randall TD
- Subjects
- Animals, Mice, TOR Serine-Threonine Kinases metabolism, Proteobacteria, Escherichia coli immunology, Neoplasms immunology, Female, Arginine metabolism, T-Lymphocytes, Regulatory immunology, Gastrointestinal Microbiome immunology, CD8-Positive T-Lymphocytes immunology, Omentum immunology, Mice, Inbred C57BL
- Abstract
Gut microbiota influence anti-tumor immunity, often by producing immune-modulating metabolites. However, microbes consume a variety of metabolites that may also impact host immune responses. We show that tumors grow unchecked in the omenta of microbe-replete mice due to immunosuppressive Tregs. By contrast, omental tumors in germ-free, neomycin-treated mice or mice colonized with altered Schaedler's flora (ASF) are spontaneously eliminated by CD8
+ T cells. These mice lack Proteobacteria capable of arginine catabolism, causing increases in serum arginine that activate the mammalian target of the rapamycin (mTOR) pathway in Tregs to reduce their suppressive capacity. Transfer of the Proteobacteria, Escherichia coli (E. coli), but not a mutant unable to catabolize arginine, to ASF mice reduces arginine levels, restores Treg suppression, and prevents tumor clearance. Supplementary arginine similarly decreases Treg suppressive capacity, increases CD8+ T cell effectiveness, and reduces tumor burden. Thus, microbial consumption of arginine alters anti-tumor immunity, offering potential therapeutic strategies for tumors in visceral adipose tissue., Competing Interests: Declaration of interests R.C.A. is a consultant for Merck, Seagen, Sutro, GSK, VBL Therapeutics, and Kiyatec and has research support from Immunogen, GSK, GOG Foundation, Champions Oncology, Exelixis, and Merck., (Copyright © 2024 Elsevier Inc. All rights reserved.)- Published
- 2024
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