Gut Microbiota Potentiates the Effect of Immune Checkpoint Therapy against Cancers
Haruka Sawamura , Kurumi Taniguchi , Yuka Ikeda , Ai Tsuji , Yasuko Kitagishi , Satoru Matsuda *
Department of Food Science and Nutrition, Nara Women's University, Kita-Uoya Nishimachi, Nara 630-8506, Japan
* Correspondence: Satoru Matsuda
Academic Editor: Lunawati L Bennett
Special Issue: Role of Diets, Vitamins, and Minerals in Cancers and Various Diseases
Received: November 16, 2021 | Accepted: February 28, 2022 | Published: March 08, 2022
Recent Progress in Nutrition 2022, Volume 2, Issue 1, doi:10.21926/rpn.2201007
Recommended citation: Sawamura H, Taniguchi K, Ikeda Y, Tsuji A, Kitagishi Y, Matsuda S. Gut Microbiota Potentiates the Effect of Immune Checkpoint Therapy against Cancers. Recent Progress in Nutrition 2022;2(1):007; doi:10.21926/rpn.2201007.
© 2022 by the authors. This is an open access article distributed under the conditions of the Creative Commons by Attribution License, which permits unrestricted use, distribution, and reproduction in any medium or format, provided the original work is correctly cited.
Immune checkpoints have been aggressively investigated for anti-cancer immunotherapy. The power of microbiota on the outcome of this immunotherapy has attracted much attention. For example, intestinal microorganisms play a key role in the effectiveness of programmed cell death 1 (PD1) and cytotoxic T lymphocyte-associated antigen 4 (CTLA4) blockade. Additionally, short-chain fatty acids produced in the gut may modulate anti-CTLA4 and anti-PD1 stimulated immune responses and their anti-tumor efficacy. Enhancing the anti-tumor effects of CTLA4 blockade depends on specific Bacteroides sp. of the gut microbiota, suggesting novel approaches to improve such immunotherapies. However, the molecular mechanism of the immune-potentiation remains largely unknown. Changes in the microbiota are influenced by dietary and environmental factors. Here, we have suggested the molecular mechanism of action regarding the interplay between gut microbiota and the anti-cancer immune system with APRO family proteins, which might contribute to innovative cancer therapy in the future.
Gut microbiota; short-chain fatty acids; immune checkpoint; PD1; CTLA-4; APRO family proteins; cancer
Cancer-therapeutics have advanced greatly with targeted immunological approaches due to the use of immune checkpoint antibodies, which is a popular method of immunotherapy against cancers . The immunotherapy via the association of several molecules such as the programmed cell death protein 1 (PD1) receptor, programmed cell death ligand 1 (PDL1), or cytotoxic T-lymphocyte associated protein 4 (CTLA4) has shown positive effects on both solid and hematological malignancies and is involved in the activation of effector T cells and their anti-tumor activity . However, even such immunotherapies frequently fail to regulate malignancies in a significant proportion of patients. Despite advances in these innovative immune treatments, cancers are still the major cause of mortality globally. The relationship between the immune system and the host gut microbiota can determine the responses to cancer immunotherapy [2,3]. Modulating the gut microbiome can also optimize therapeutic outcomes by blocking immune checkpoints. For example, it is crucial to determine the relationship between gut microbiota and the immunomodulatory effects of CTLA4 blockade  (Figure 1). The anti-tumor effects of CTLA4 blockade depend on specific Bacteroides sp., including B. thetaiotaomicron and/or B. fragilis . Tumors in antibiotic-treated mice do not respond to CTLA4 blockade suggesting that the effective bacteria probably die due to the antibiotic treatment. This effect-deficiency was overcome by gavage with Bacteroides sp. and/or by transferring specific T cells against B. fragilis . Fecal microbial transplantation in mice also confirmed that treatment with antibodies against PD1 favored the growth of Parabacteroides distasonis and B. vulgatus with anti-cancer properties . This study shows an important role of gut microbiota, including Bacteroides sp., in the immune-stimulatory effects of PD1 or CTLA4 blockade. (Table 1) Additionally, baseline gut microbiota enriched with Faecalibacterium and other Firmicutes has been associated with clinically beneficial responses to ipilimumab, which is an anti-PD1 or anti-PDL1-based therapy in melanoma patients . Faecalibacterium sp. also represents a key feature associated with clinical responses in patients who undergo immune checkpoint therapy. These results are encouraging. However, some studies have explained how the gut microbiota might affect the distant lesion during malignancies. Additionally, avoiding gut dysbiosis during cancer treatment may be required to retain the beneficial bacteria in the host. The depletion of regulatory T-cells (Tregs) enhances the anti-tumor effect of CTLA4 blockade . Therefore, the mechanism to regulate the number of Tregs should be further investigated to determine the effectiveness of the gut microbiota in future studies.
Figure 1 A schematic illustration of the relationship among gut microbiota, cytotoxic T cells, cancer cells, and immune checkpoint inhibitors. Immune checkpoint molecules are involved in cell-cell communication; these molecules are present on T cells and/or shared among cancer cells. Immune checkpoint molecules send signals to inhibit T cell activities associated with killing cancer cells. Monoclonal antibodies are used as therapeutic checkpoint inhibitors. The gut microbiota activates cytotoxic T cells through different mechanisms, including the production of SCFAs. Certain beneficial microbial species have several effects on anti-cancer immune responses. An arrowhead indicates stimulation and/or augmentation. Some critical events have been omitted for clarity.
Table 1 The microbial species that may enhance the effect of CTLA-4 or PD-1 blockade.
The intestinal epithelium maintains homeostasis and the health of the host via the immune system . Therefore, the gut microbiota has been studied extensively for disease prediction and/or prevention. Perturbation of symbiosis might cause chronic inflammatory and/or autoimmune pathogenesis . Furthermore, dysbiosis can enhance the signal of harmful microbiota, which often produce dangerous metabolites leading to maladaptive responses . However, certain genera of microbiota might have a beneficial effect on immune responses . The term microbiota refers to a community of commensal and/or pathogenic microorganisms that can colonize various regions within the body, including the oral cavity, intestinal tract, respiratory system, skin, etc. These populations involve trillions of microbial cells such as bacteria, fungi, and viruses, which influence many homeostatic processes, such as the synthesis of vitamins, energy metabolism, fat storage, and regulation of immune responses . Some bacterial groups can produce valuable metabolites, including short-chain fatty acids (SCFAs) such as acetate, propionate, and butyrate . The SCFAs may provide energy to intestinal epithelial cells . Additionally, SCFAs also perform important functions in immune cells, such as maintaining homeostasis and/or the health of the host . For example, butyrate exerts systemic anti-inflammatory effects by affecting immune cell proliferation, migration, and cytokine expression, which are associated with immunomodulatory capacities by inducing Treg cells . Firmicutes and F. prausnitzii, often found in the gut, are known for their butyrate-producing capabilities . The abundance of butyrate-producing bacteria is significantly lower in patients with colorectal cancers . A relationship between the composition of the gut microbiota and the response to ipilimumab via the microbiota-derived SCFAs was found  (Figure 1). Anti-CTLA-blocking mAb can also induce dysbiosis and might stimulate dendritic cells and specific Th1 cells to recognize for tumor cells via the action of SCFAs . Some SCFAs are associated with clinical outcomes in patients treated with anti-PD1/PDL1 . Some species of bacteria, such as Bifidobacterium, are associated with an increase in the maturation of dendritic cells leading to augmented CD8+ T cell priming and/or accumulation due to PD1/PDL1 blockade by their specific antibodies [7,21,22]. On the contrary, high systemic levels of butyrate and/or propionate can limit the anti-tumor activity. For example, high blood butyrate and propionate levels are associated with resistance to CTLA4 blockade and the production of a higher amount of Tregs . SCFAs function via specific receptors such as GPR41, GPR43, and GPR109A expressed on immune cells . However, the molecular mechanism through which SCFAs contribute to immune-potentiation remains largely unknown. The identification of a definite pathway responsible for SCFA-associated immunomodulatory effects could represent a paradigm that might allow the discovery of targets to substantially improve the effectiveness of immune checkpoint therapy. Even at distant sites in the body, anti-cancer responses due to immune checkpoint therapy could be influenced by the small molecular SCFAs . Diet can effectively determine the integrity of the gut microbiota . Therefore, dietary factors can determine the health or disease state and might be a risk factor for diseases or could be used for therapy against diseases. The characterization of dietary factors for immune checkpoint therapy is currently unsatisfactory.
The antiproliferative (APRO) protein family  is involved in diverse human diseases, including cancer, suggesting that APRO members are involved in pathological or carcinogenic processes such as cell proliferation, apoptosis, autophagy, and other cellular functions as tumor suppressors. Additionally, these proteins have been associated with various physiological processes in the cell, including cell division, DNA repair, transcriptional regulation, and messenger RNA (mRNA) stability [27,28]. Significant prognostic effects of the APRO family after cancer therapy have been found in various cancers . The expression of some members of the APRO family differs significantly between cancer and normal tissues [30,31]. Furthermore, some APRO genes, including TOB1, are involved in chronic myelogenous leukemia (CML). APRO genes have a low expression in patients with CML without cytogenetic responses . Similarly, a low expression of TOB1 occurs in resistant patients with CML compared to therapy-responsive patients . This might be related to the TOB1 signaling pathway causing resistance to therapy. Besides affecting cellular differentiation, APRO family proteins may play a dynamic role in maintaining cellular homeostasis during redox stress and/or carcinogenesis. Through genomic profiling of B-cell leukemia and lymphoma, BTG1 was found to suppress tumors [33,34]. Moreover, a decrease in the expression of APRO family proteins is often associated with malignancy and/or poor treatment outcomes in solid tumors. For example, TOB1 and TOB2 are inactivated in various cancers, including solid tumors and/or leukemia . Additionally, a decrease in TOB1 expression is associated with aggressive tumor-like behavior and poor prognosis in stomach cancer [30,31,36]. Recently, the relationship between microRNAs (miRNAs) and APRO expression has attracted considerable attention. For example, miR-21 regulates the BTG2 gene during carcinogenesis . Moreover, miR-32–5p is significantly upregulated in colorectal cancer tissues compared to their levels in the adjacent normal tissues. It regulates the radio-sensitivity, migration, and invasion of colorectal cancer cells by inhibiting and/or decreasing TOB1 expression . By affecting proliferation via the regulation of certain miRNAs, APRO family proteins might play an important role in maintaining homeostasis in normal healthy cells under physiological conditions during carcinogenesis. Growth suppression by adenovirus-mediated TOB1 protein expression in pancreatic cancer suggests an application of APRO proteins for chemotherapy-resistant cancer peritonitis . The relationship between APRO proteins and carcinogenesis in a cell may be similar to the relationship between cytotoxic T cells and cancer cells  (Figure 2). Additionally, TOB1 expression in colon epithelium might increase and/or be upregulated by the stimulation of certain gut microbiota [unpublished data, 41, 42]. Thus, gut microbiota might potentiate the effect not only of the “Immune checkpoint therapy” but also of the “Onco-checkpoints” (Figure 2). Probiotic bacteria may be administered for supporting cancer treatment. Identifying such supportive mechanisms may provide a promising strategy for probiotic-based dietary therapies, which may be integrated with cancer therapy to improve the outcomes of the therapy and the quality of life of the patients. However, this has to be demonstrated and should be a part of future research.
Figure 2 The relationship between cytotoxic T-cells and cancer cells is similar to the relationship of tumor suppressors with the APRO family proteins and oncogenesis. It could be hypothesized that the former is regulated by immune checkpoint molecules, such as PD1/PDL1 and CTLA4, while the latter might be regulated by various miRNAs. The gut commensal microbiota might support both sides of the anti-cancer potential against cancer cells and/or oncogenesis.
BTG: B cell translocation gene
CML: chronic myelogenous leukemia
CTLA4: cytotoxic T lymphocyte-associated protein 4
PD1: programmed cell death protein 1
PDL1: programmed cell death ligand 1
ROS: reactive oxygen species
SCFAs: short-chain fatty acids
SOD: superoxide dismutase
TIS: tetradecanoyl phorbol acetate-inducible sequences
TOB: transducer of ErbB2
Tregs: regulatory T-cells
Each author (HS, KT, YI, AT, YK, SM) has participated sufficiently in this work of drafting the article and/or revising the article for the important rational content. Then, all authors gave final approval of the version to be submitted.
The authors have declared that no competing interests exist.
- Goebeler ME, Bargou RC. T cell-engaging therapies - BiTEs and beyond. Nat Rev Clin Oncol. 2020; 17: 418-434. [CrossRef]
- Vétizou M, Pitt JM, Daillère R, Lepage P, Waldschmitt N, Flament C, et al. Anticancer immunotherapy by CTLA-4 blockade relies on the gut microbiota. Science. 2015; 350: 1079-1084. [CrossRef]
- Lee SH, Cho SY, Yoon Y, Park C, Sohn J, Jeong JJ, et al. Bifidobacterium bifidum strains synergize with immune checkpoint inhibitors to reduce tumour burden in mice. Nat Microbiol. 2021; 6: 277-288. [CrossRef]
- Zhuo Q, Yu B, Zhou J, Zhang J, Zhang R, Xie J, et al. Lysates of Lactobacillus acidophilus combined with CTLA-4-blocking antibodies enhance antitumor immunity in a mouse colon cancer model. Sci Rep. 2019; 9: 20128. [CrossRef]
- Ahmadi Badi S, Moshiri A, Ettehad Marvasti F, Mojtahedzadeh M, Kazemi V, Siadat SD. Extraction and evaluation of outer membrane vesicles from two important gut microbiota members, bacteroides fragilis and bacteroides thetaiotaomicron. Cell J. 2020; 22: 344-349.
- Huang J, Liu D, Wang Y, Liu L, Li J, Yuan J, et al. Ginseng polysaccharides alter the gut microbiota and kynurenine/tryptophan ratio, potentiating the antitumour effect of antiprogrammed cell death 1/programmed cell death ligand 1 (anti-PD-1/PD-L1) immunotherapy. Gut. 2021. doi:10.1136/gutjnl-2020-321031. [CrossRef]
- Chaput N, Lepage P, Coutzac C, Soularue E, Le Roux K, Monot C, et al. Baseline gut microbiota predicts clinical response and colitis in metastatic melanoma patients treated with ipilimumab. Ann Oncol. 2017; 28: 1368-1379. [CrossRef]
- Sun S, Luo L, Liang W, Yin Q, Guo J, Rush AM, et al. Bifidobacterium alters the gut microbiota and modulates the functional metabolism of T regulatory cells in the context of immune checkpoint blockade. Proc Natl Acad Sci U S A. 2020; 117: 27509-27515. [CrossRef]
- Seo K, Seo J, Yeun J, Choi H, Kim YI, Chang SY. The role of mucosal barriers in human gut health. Arch Pharm Res. 2021; 44: 325-341. [CrossRef]
- Pitt JM, Vétizou M, Waldschmitt N, Kroemer G, Chamaillard M, Boneca IG, et al. Fine-tuning cancer immunotherapy: Optimizing the gut microbiome. Cancer Res. 2016; 76: 4602-4607. [CrossRef]
- Cario E. Toll-like receptors in the pathogenesis of chemotherapy-induced gastrointestinal toxicity. Curr Opin Support Palliat Care. 2016; 10: 157-164. [CrossRef]
- Wu Y, Li Q, Liu J, Liu Y, Xu Y, Zhang R, et al. Integrating serum metabolome and gut microbiome to evaluate the benefits of lauric acid on lipopolysaccharide- challenged broilers. Front Immunol. 2021; 12: 759323. [CrossRef]
- Altveş S, Yildiz HK, Vural HC. Interaction of the microbiota with the human body in health and diseases. Biosci Microbiota Food Health. 2020; 39: 23-32. [CrossRef]
- Maldonado-Mateus LY, Perez-Burillo S, Lerma-Aguilera A, Hinojosa-Nogueira D, Ruíz-Pérez S, Gosalbes MJ, et al. Effect of roasting conditions on cocoa bioactivity and gut microbiota modulation. Food Funct. 2021; 12: 9680-9692. [CrossRef]
- Ballout J, Akiba Y, Kaunitz JD, Diener M. Short-chain fatty acid receptors involved in epithelial acetylcholine release in rat caecum. Eur J Pharmacol. 2021; 906: 174292. [CrossRef]
- Yao Y, Cai X, Fei W, Ye Y, Zhao M, Zheng C. The role of short-chain fatty acids in immunity, inflammation and metabolism. Crit Rev Food Sci Nutr. 2020; 1: 1-12. [CrossRef]
- Liang X, Liu CS, Wei XH, Xia T, Chen FL, Tang QF, et al. Mahuang Fuzi Xixin Decoction ameliorates allergic rhinitis in rats by regulating the gut microbiota and Th17/Treg balance. J Immunol Res. 2020; 2020: 6841078 [CrossRef]
- Tanno H, Fujii T, Hirano K, Maeno S, Tonozuka T, Sakamoto M, et al. Characterization of fructooligosaccharide metabolism and fructooligosaccharide-degrading enzymes in human commensal butyrate producers. Gut Microbes. 2021; 13: 1869503. [CrossRef]
- Coutzac C, Jouniaux JM, Paci A, Schmidt J, Mallardo D, Seck A, et al. Systemic short chain fatty acids limit antitumor effect of CTLA-4 blockade in hosts with cancer. Nat Commun. 2020; 11: 2168. [CrossRef]
- Ferrere G, Tidjani Alou M, Liu P, Goubet AG, Fidelle M, Kepp O, et al. Ketogenic diet and ketone bodies enhance the anticancer effects of PD-1 blockade. JCI Insight. 2021; 6: e145207. [CrossRef]
- Salek Farrokhi A, Darabi N, Yousefi B, Askandar RH, Shariati M, Eslami M. Is it true that gut microbiota is considered as panacea in cancer therapy? J Cell Physiol. 2019, 234: 14941-14950. [CrossRef]
- Gopalakrishnan V, Spencer CN, Nezi L, Reuben A, Andrews MC, Karpinets TV, et al. Gut microbiome modulates response to anti-PD-1 immunotherapy in melanoma patients. Science. 2018; 359: 97-103. [CrossRef]
- Liu Y, Li YJ, Loh YW, Singer J, Zhu W, Macia L, et al. Fiber derived microbial metabolites prevent acute kidney injury through G-protein coupled receptors and HDAC inhibition. Front Cell Dev Biol. 2021; 9: 648639. [CrossRef]
- Roberti MP, Yonekura S, Duong CPM, Picard M, Ferrere G, Tidjani Alou M, et al. Chemotherapy-induced ileal crypt apoptosis and the ileal microbiome shape immunosurveillance and prognosis of proximal colon cancer. Nat Med. 2020; 26: 919-931. [CrossRef]
- Trakman GL, Fehily S, Basnayake C, Hamilton AL, Russell E, Wilson-O'Brien A, et al. Diet and gut microbiome in gastrointestinal disease. J Gastroenterol Hepatol. 2022, 37: 237-245. [CrossRef]
- Matsuda S, Rouault J, Magaud J, Berthet C. In search of a function for the TIS21/PC3/BTG1/TOB family. FEBS Lett. 2001; 497: 67-72. [CrossRef]
- Tirone F. The gene PC3(TIS21/BTG2), prototype member of the PC3/BTG/TOB family: regulator in control of cell growth, differentiation, and DNA repair? J Cell Physiol. 2001; 187: 155-165. [CrossRef]
- Sun KK, Zhong N, Yang Y, Zhao L, Jiao Y. Enhanced radiosensitivity of NSCLC cells by transducer of erbB2.1 (TOB1) through modulation of the MAPK/ERK pathway. Oncol Rep. 2013; 29: 2385-2391. [CrossRef]
- Bai Y, Qiao L, Xie N, Shi Y, Liu N, Wang J. Expression and prognosis analyses of the Tob/BTG antiproliferative (APRO) protein family in human cancers. PLoS One. 2017; 12: e0184902. [CrossRef]
- Guan R, Peng L, Wang D, He H, Wang D, Zhang R, et al. Decreased TOB1 expression and increased phosphorylation of nuclear TOB1 promotes gastric cancer. Oncotarget. 2017; 8: 75243-75253. [CrossRef]
- Zhang SQ, Sun KK, Wu XY, Zhong N, Zhao H, Li DC. Clinicopathological significance of cytoplasmic transducer of ErbB2. 1 expression in gastric cancer. Mol Med Rep. 2015; 12: 1177-1182. [CrossRef]
- Mascarenhas Cdo C, Ferreira da Cunha A, Brugnerotto AF, Gambero S, de Almeida MH, Carazzolle MF, et al. Identification of target genes using gene expression profile of granulocytes from patients with chronic myeloid leukemia treated with tyrosine kinase inhibitors. Leuk Lymphoma. 2014; 55: 1861-1869. [CrossRef]
- Yuniati L, Scheijen B, van der Meer LT, van Leeuwen FN. Tumor suppressors BTG1 and BTG2: Beyond growth control. J Cell Physiol. 2019; 234: 5379-5389. [CrossRef]
- Herling CD, Abedpour N, Weiss J, Schmitt A, Jachimowicz RD, Merkel O, et al. Clonal dynamics towards the development of venetoclax resistance in chronic lymphocytic leukemia. Nat Commun. 2018; 9: 727. [CrossRef]
- Kundu J, Wahab SM, Kundu JK, Choi YL, Erkin OC, Lee HS, et al. Tob1 induces apoptosis and inhibits proliferation, migration and invasion of gastric cancer cells by activating Smad4 and inhibiting beta-catenin signaling. Int J Oncol. 2012; 41: 839-848. [CrossRef]
- Guo H, Zhang R, Afrifa J, Wang Y, Yu J. Decreased expression levels of DAL-1 and TOB1 are associated with clinicopathological features and poor prognosis in gastric cancer. Pathol Res Pract. 2019; 215: 152403. [CrossRef]
- Kopczyńska E. Role of microRNAs in the resistance of prostate cancer to docetaxel and paclitaxel. Contemp Oncol (Pozn). 2015; 19: 423-427. [CrossRef]
- Liang H, Tang Y, Zhang H, Zhang C. MiR-32-5p regulates radiosensitization, migration and invasion of colorectal cancer cells by targeting TOB1 gene. Onco Targets Ther.2019; 12: 9651-9661. [CrossRef]
- Yanagie H, Tanabe T, Sumimoto H, Sugiyama H, Matsuda S, Nonaka Y, et al. Tumor growth suppression by adenovirus-mediated introduction of a cell-growth-suppressing gene tob in a pancreatic cancer model. Biomed Pharmacother. 2009; 63: 275-286. [CrossRef]
- Ikeda Y, Taniguchi K, Nagase N, Tsuji A, Kitagishi Y, Matsuda S. Reactive oxygen species may influence on the crossroads of stemness, senescence, and carcinogenesis in a cell via the roles of APRO family proteins. Explor Med. 2021; 2: 443-454. doi: 10.37349/emed.2021.00062. [CrossRef]
- Li D, Xiao L, Ge Y, Fu Y, Zhang W, Cao H, et al. High expression of Tob1 indicates poor survival outcome and promotes tumour progression via a Wnt positive feedback loop in colon cancer. Mol Cancer. 2018; 17: 159. [CrossRef]
- Fonseca-Camarillo G, Furuzawa-Carballeda J, Priego-Ranero ÁA, Martínez-Benítez B, Barreto-Zúñiga R, Yamamoto-Furusho JK. Expression of TOB/BTG family members in patients with inflammatory bowel disease. Scand J Immunol. 2021; 93: e13004. [CrossRef]