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Forsyth CB, Shaikh M, Engen PA, Preuss F, Naqib A, Palmen BA, Green SJ, Zhang L, Bogin ZR, Lawrence K, Sharma D, Swanson GR, Bishehsari F, Voigt RM, Keshavarzian A. Evidence that the loss of colonic anti-microbial peptides may promote dysbiotic Gram-negative inflammaging-associated bacteria in aging mice. FRONTIERS IN AGING 2024; 5:1352299. [PMID: 38501032 PMCID: PMC10945560 DOI: 10.3389/fragi.2024.1352299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 02/02/2024] [Indexed: 03/20/2024]
Abstract
Introduction: Aging studies in humans and mice have played a key role in understanding the intestinal microbiome and an increased abundance of "inflammaging" Gram-negative (Gn) bacteria. The mechanisms underlying this inflammatory profile in the aging microbiome are unknown. We tested the hypothesis that an aging-related decrease in colonic crypt epithelial cell anti-microbial peptide (AMP) gene expression could promote colonic microbiome inflammatory Gn dysbiosis and inflammaging. Methods: As a model of aging, C57BL/6J mice fecal (colonic) microbiota (16S) and isolated colonic crypt epithelial cell gene expression (RNA-seq) were assessed at 2 months (mth) (human: 18 years old; yo), 15 mth (human: 50 yo), and 25 mth (human: 84 yo). Informatics examined aging-related microbial compositions, differential colonic crypt epithelial cell gene expressions, and correlations between colonic bacteria and colonic crypt epithelial cell gene expressions. Results: Fecal microbiota exhibited significantly increased relative abundances of pro-inflammatory Gn bacteria with aging. Colonic crypt epithelial cell gene expression analysis showed significant age-related downregulation of key AMP genes that repress the growth of Gn bacteria. The aging-related decrease in AMP gene expressions is significantly correlated with an increased abundance in Gn bacteria (dysbiosis), loss of colonic barrier gene expression, and senescence- and inflammation-related gene expression. Conclusion: This study supports the proposed model that aging-related loss of colonic crypt epithelial cell AMP gene expression promotes increased relative abundances of Gn inflammaging-associated bacteria and gene expression markers of colonic inflammaging. These data may support new targets for aging-related therapies based on intestinal genes and microbiomes.
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Affiliation(s)
- Christopher B. Forsyth
- Department of Internal Medicine, Rush University Medical Center, Chicago, IL, United States
- Rush Center for Integrated Microbiome and Chronobiology Research, Rush University Medical Center, Chicago, IL, United States
- Department of Anatomy and Cell Biology, Rush University Medical Center, Chicago, IL, United States
| | - Maliha Shaikh
- Rush Center for Integrated Microbiome and Chronobiology Research, Rush University Medical Center, Chicago, IL, United States
| | - Phillip A. Engen
- Rush Center for Integrated Microbiome and Chronobiology Research, Rush University Medical Center, Chicago, IL, United States
| | - Fabian Preuss
- Department of Biological Sciences, University of Wisconsin Parkside, Kenosha, WI, United States
| | - Ankur Naqib
- Rush Center for Integrated Microbiome and Chronobiology Research, Rush University Medical Center, Chicago, IL, United States
- Genomics and Microbiome Core Facility, Rush University Medical Center, Chicago, IL, United States
| | - Breanna A. Palmen
- Department of Biological Sciences, University of Wisconsin Parkside, Kenosha, WI, United States
| | - Stefan J. Green
- Rush Center for Integrated Microbiome and Chronobiology Research, Rush University Medical Center, Chicago, IL, United States
- Genomics and Microbiome Core Facility, Rush University Medical Center, Chicago, IL, United States
| | - Lijuan Zhang
- Rush Center for Integrated Microbiome and Chronobiology Research, Rush University Medical Center, Chicago, IL, United States
| | - Zlata R. Bogin
- Rush Center for Integrated Microbiome and Chronobiology Research, Rush University Medical Center, Chicago, IL, United States
| | - Kristi Lawrence
- Rush Center for Integrated Microbiome and Chronobiology Research, Rush University Medical Center, Chicago, IL, United States
| | - Deepak Sharma
- Rush Center for Integrated Microbiome and Chronobiology Research, Rush University Medical Center, Chicago, IL, United States
| | - Garth R. Swanson
- Department of Internal Medicine, Rush University Medical Center, Chicago, IL, United States
- Rush Center for Integrated Microbiome and Chronobiology Research, Rush University Medical Center, Chicago, IL, United States
- Department of Anatomy and Cell Biology, Rush University Medical Center, Chicago, IL, United States
| | - Faraz Bishehsari
- Department of Internal Medicine, Rush University Medical Center, Chicago, IL, United States
- Rush Center for Integrated Microbiome and Chronobiology Research, Rush University Medical Center, Chicago, IL, United States
- Department of Anatomy and Cell Biology, Rush University Medical Center, Chicago, IL, United States
| | - Robin M. Voigt
- Department of Internal Medicine, Rush University Medical Center, Chicago, IL, United States
- Rush Center for Integrated Microbiome and Chronobiology Research, Rush University Medical Center, Chicago, IL, United States
- Department of Anatomy and Cell Biology, Rush University Medical Center, Chicago, IL, United States
| | - Ali Keshavarzian
- Department of Internal Medicine, Rush University Medical Center, Chicago, IL, United States
- Rush Center for Integrated Microbiome and Chronobiology Research, Rush University Medical Center, Chicago, IL, United States
- Department of Anatomy and Cell Biology, Rush University Medical Center, Chicago, IL, United States
- Department of Physiology, Rush University Medical Center, Chicago, IL, United States
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Schumacher MA. The emerging roles of deep crypt secretory cells in colonic physiology. Am J Physiol Gastrointest Liver Physiol 2023; 325:G493-G500. [PMID: 37697924 PMCID: PMC10887841 DOI: 10.1152/ajpgi.00093.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 08/18/2023] [Accepted: 09/03/2023] [Indexed: 09/13/2023]
Abstract
Deep crypt secretory (DCS) cells are a population of epithelial cells located at the colonic crypt base that share some similarities to Paneth and goblet cells. They were initially defined as c-Kit expressing cells, though subsequent work showed that they are more specifically marked by Reg4 in the murine colon. The best-understood function of DCS cells at present is supporting the stem cell niche by generating Notch and EGF ligands. However, as these cells also express immunoregulatory (e.g., Ccl6) and host defense (e.g., Retnlb) genes, it is likely they have additional functions in maintaining colonic health outside of maintenance of the stem niche. Recent advances in single-cell transcriptomic profiling hint at additional epithelial and immune roles that may exist for these cells and have aided in elucidating their developmental lineage. This review highlights the emerging evidence supporting a crucial role for DCS cells in intestinal physiology, the current understanding of how these cells are regulated, and their potential role(s) in colonic disease.
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Affiliation(s)
- Michael A Schumacher
- Department of Pediatrics, University of Southern California Keck School of Medicine, Los Angeles, California, United States
- The Saban Research Institute, Children's Hospital Los Angeles, Los Angeles, California, United States
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Tanaka S, Orita H, Kataoka T, Miyazaki M, Saeki H, Wada R, Brock MV, Fukunaga T, Amano T, Shiroishi T. Gasdermin D represses inflammation-induced colon cancer development by regulating apoptosis. Carcinogenesis 2023; 44:341-349. [PMID: 36753047 DOI: 10.1093/carcin/bgad005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 12/07/2022] [Accepted: 02/06/2023] [Indexed: 02/09/2023] Open
Abstract
Chronic inflammation is widely recognized as a major risk factor for cancer formation, but the underlying mechanisms are poorly understood. Recently, it was shown that Gasdermin D (GSDMD) protein drives pyroptotic cell death in macrophages on cleavage by inflammatory caspases. Even though the Gsdmd gene is specifically expressed in the intestinal epithelium, the role of Gsdmd in the intestinal tissues remains poorly characterized. In this study, we examined the biological role of Gsdmd in colorectal cancer (CRC) development, employing an azoxymethane/dextran sulfate sodium carcinogenesis model. Results show that GSDMD deficiency enhances CRC development, probably due to decreased apoptosis caused by downregulation of interferon-gamma (IFNγ)-signal transducer and activator 1 (STAT1) signaling. Furthermore, we show that GSDMD protein is diminished in human colorectal cancer, indicating involvement of GSDMD in repression of CRC development in humans. Our findings provide a new insight into functions of Gsdmd/GSDMD in colonic inflammation and human CRC development.
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Affiliation(s)
- Shigekazu Tanaka
- Mammalian Genetics Laboratory, Genetic Strains Research Center, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan
| | - Hajime Orita
- Shizuoka Medical Research Center for Disaster, Juntendo University, Shizuoka Hospital, 1129 Nagaoka, Izunokuni, Shizuoka 410-2295, Japan
- Department of Gastroenterology, Juntendo University School of Medicine, 2-1-1 Hongo Bunkyo Ward, Tokyo 113-8421, Japan
| | - Taro Kataoka
- Shizuoka Medical Research Center for Disaster, Juntendo University, Shizuoka Hospital, 1129 Nagaoka, Izunokuni, Shizuoka 410-2295, Japan
| | - Masahiro Miyazaki
- Shizuoka Medical Research Center for Disaster, Juntendo University, Shizuoka Hospital, 1129 Nagaoka, Izunokuni, Shizuoka 410-2295, Japan
| | - Harumi Saeki
- Department of Pathology, Juntendo University School of Medicine, 2-1-1 Hongo Bunkyo Ward, Tokyo 113-8421, Japan
| | - Ryo Wada
- Department of Pathology, Juntendo University Shizuoka Hospital, 1129 Nagaoka, Izunokuni, Shizuoka 410-2295, Japan
| | - Malcolm V Brock
- Department of Surgery, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Tetsu Fukunaga
- Department of Gastroenterology, Juntendo University School of Medicine, 2-1-1 Hongo Bunkyo Ward, Tokyo 113-8421, Japan
| | - Takanori Amano
- Mammalian Genetics Laboratory, Genetic Strains Research Center, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan
- Next Generation Human Disease Model Team, RIKEN BioResource Research Center, Tsukuba 305-0074, Japan
| | - Toshihiko Shiroishi
- Mammalian Genetics Laboratory, Genetic Strains Research Center, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan
- RIKEN BioResource Research Center, Tsukuba 305-0074, Japan
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Effects of human adipose tissue- and bone marrow-derived mesenchymal stem cells on airway inflammation and remodeling in a murine model of chronic asthma. Sci Rep 2022; 12:12032. [PMID: 35835804 PMCID: PMC9283392 DOI: 10.1038/s41598-022-16165-8] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Accepted: 07/05/2022] [Indexed: 12/03/2022] Open
Abstract
It is challenging to overcome difficult-to-treat asthma, and cell-based therapies are attracting increasing interest. We assessed the effects of mesenchymal stem cell (MSC) treatments using a murine model of chronic ovalbumin (OVA)-challenged asthma. We developed a murine model of chronic allergic asthma using OVA sensitization and challenge. Human adipose-derived MSCs (hADSCs) or human bone marrow-derived MSCs (hBMSCs) were administered. We measured the levels of resistin-like molecule-β (RELM-β). We also measured RELM-β in asthma patients and normal controls. OVA-challenged mice exhibited increased airway hyper-responsiveness, inflammation, and remodeling. hBMSC treatment remarkably decreased airway hyper-responsiveness but hADSC treatment did not. Both MSCs alleviated airway inflammation, but hBMSCs tended to have a more significant effect. hBMSC treatment reduced Th2-cytokine levels but hADSC treatment did not. Both treatments reduced airway remodeling. The RELM-β level decreased in the OVA-challenged control group, but increased in both treatment groups. We found that the serum level of RELM-β was lower in asthma patients than controls. MSC treatments alleviated the airway inflammation, hyper-responsiveness, and remodeling associated with chronic asthma. hBMSCs were more effective than hADSCs. The RELM-β levels increased in both treatment groups; the RELM-β level may serve as a biomarker of MSC treatment efficacy.
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Che L, Yu C, Chen G, Lin J, Xie Z, Xia T, Luo W, Cai X, Liu S. The Inflammatory Response Induced by RELMβ Upregulates IL-8 and IL-1β Expression in Bronchial Epithelial Cells in COPD. Int J Chron Obstruct Pulmon Dis 2021; 16:2503-2513. [PMID: 34511895 PMCID: PMC8421257 DOI: 10.2147/copd.s321877] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Accepted: 08/23/2021] [Indexed: 01/04/2023] Open
Abstract
Purpose Chronic obstructive pulmonary disease (COPD) is associated with a complex inflammatory regulatory network. Resistin-like molecule β (RELMβ) is highly expressed in the lungs of COPD patients. We aimed to investigate the proinflammatory effect of RELMβ on airway epithelial cells in COPD. Methods First, a GEO dataset was used to analyze the expression of the RELMβ gene in the COPD and control groups as well as the protein levels of RELMβ in the sera of outpatients with COPD and normal control subjects in our hospital. We also stimulated 16HBE bronchial epithelial cells with recombinant RELMβ protein and analyzed the expression of IL-8 and IL-1β. We upregulated and downregulated the gene expression of RELMβ in 16HBE cells and analyzed the expression of the inflammatory cytokines IL-8 and IL-1β. In addition, we also examined the mechanism by which the p38 MAPK signaling pathway contributed to the regulation of IL-8 and IL-1β expression by RELMβ. Results RELMβ expression was increased in COPD tissues in different data sets and in the serum of COPD patients in our hospital. IL-8 and IL-1β expression was also increased in COPD tissues with high RELMβ gene expression in different data sets. The RELMβ gene was mainly related to inflammatory factors and inflammatory signaling pathways in the PPI regulatory network. Experiments at the cellular level showed that RELMβ promoted the expression of the inflammatory cytokines IL-8 and IL-1β, and this regulation was mediated by the p38 MAPK signaling pathway. Conclusion RELMβ can promote the expression of the inflammatory cytokines IL-8 and IL-1β in bronchial epithelial cells of patients with COPD and exert inflammatory effects. RELMβ may be a potential target for the treatment of COPD.
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Affiliation(s)
- Li Che
- Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital of Jinan University, Guangzhou, 510630, People's Republic of China
| | - Chao Yu
- Department of Pulmonary and Critical Care Medicine, Lu'an People's Hospital of Anhui Province, Lu'an, 237016, People's Republic of China
| | - Guangshu Chen
- Department of Endocrinology, Guangzhou Red Cross Hospital, The Affiliated Hospital of Jinan University, Guangzhou, 510220, People's Republic of China
| | - Jiaxin Lin
- Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital of Jinan University, Guangzhou, 510630, People's Republic of China
| | - Zhefan Xie
- Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital of Jinan University, Guangzhou, 510630, People's Republic of China
| | - Tingting Xia
- Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital of Jinan University, Guangzhou, 510630, People's Republic of China
| | - Wenzhi Luo
- Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital of Jinan University, Guangzhou, 510630, People's Republic of China
| | - Xingdong Cai
- Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital of Jinan University, Guangzhou, 510630, People's Republic of China
| | - Shengming Liu
- Department of Pulmonary and Critical Care Medicine, The First Affiliated Hospital of Jinan University, Guangzhou, 510630, People's Republic of China
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Li Y, Yu C, Deng W. Roles and mechanisms of adipokines in drug resistance of tumor cells. Eur J Pharmacol 2021; 899:174019. [PMID: 33722588 DOI: 10.1016/j.ejphar.2021.174019] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2020] [Revised: 02/06/2021] [Accepted: 03/10/2021] [Indexed: 02/06/2023]
Abstract
The drug resistance of cancer cells has become one of the biggest obstacles of effective anticancer treatments. Adipocytes produce plenty of cytokines (also known as adipokines), which remarkably affect the drug resistance exhibited by cancer cells. Different adipokines (leptin, visfatin, resistin, adiponectin, Interleukin 6, and tumor necrosis factor α) can induce drug resistance in different cancer cells by various functional mechanisms. This phenomenon is of great interest in pharmacological anti-cancer studies since it indicates that in the cancers with adipocyte-rich microenvironment, all adipokines join together to assist cancer cells to survive by facilitating drug resistance. Studies on adipokines contribute to the development of novel pharmacological strategies for cancer therapy if their roles and molecular targets are better understood. The review will elucidate the roles and the underlying mechanisms of adipokines in drug resistance, which may be of great significance for revealing new strategies for cancer treatment.
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Affiliation(s)
- Yan Li
- Department of Immunology, Tianjin Key Laboratory of Cellular and Molecular Immunology, Key Laboratory of Diseases and Microenvironment of Ministry of Education of China, Tianjin Medical University, Tianjin, China
| | - Chunyan Yu
- Department of Immunology, Tianjin Key Laboratory of Cellular and Molecular Immunology, Key Laboratory of Diseases and Microenvironment of Ministry of Education of China, Tianjin Medical University, Tianjin, China
| | - Weimin Deng
- Department of Immunology, Tianjin Key Laboratory of Cellular and Molecular Immunology, Key Laboratory of Diseases and Microenvironment of Ministry of Education of China, Tianjin Medical University, Tianjin, China.
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Razi S, Baradaran Noveiry B, Keshavarz-Fathi M, Rezaei N. IL-17 and colorectal cancer: From carcinogenesis to treatment. Cytokine 2019; 116:7-12. [PMID: 30684916 DOI: 10.1016/j.cyto.2018.12.021] [Citation(s) in RCA: 83] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 12/03/2018] [Accepted: 12/26/2018] [Indexed: 12/15/2022]
Abstract
Colorectal cancer (CRC) is one of the most common types of cancer in the world. Several factors contribute to the development of this cancer. Tumor formation in colon triggers immune responses such as immune cells proliferation, phenotype alteration, cytokine synthesis and release, which lead to IL-17 producing T cells, the differentiated CD4+ T cells i.e. T helper 17. IL-17 is a pro-inflammatory cytokine, which its level is up regulated in serum and tissues of CRC patients. Several studies have shown that IL-17 has an important role in metastasis and prognosis of CRC. The aim of this review is to summarize the role of this cytokine in tumorigenesis, angiogenesis and metastasis of CRC and discuss its value in diagnosis, prognosis and treatment of CRC.
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Affiliation(s)
- Sepideh Razi
- Cancer Immunology Project (CIP), Universal Scientific Education and Research Network (USERN), Tehran, Iran; Student Research Committee, School of Medicine, Iran University of Medical Sciences, Tehran, Iran
| | - Behnoud Baradaran Noveiry
- Division of Cardiology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Cancer Immunology Project (CIP), Universal Scientific Education and Research Network (USERN), Baltimore, MD, USA
| | - Mahsa Keshavarz-Fathi
- Cancer Immunology Project (CIP), Universal Scientific Education and Research Network (USERN), Tehran, Iran; Students' Scientific Research Center, Tehran University of Medical Sciences, Tehran, Iran; Research Center for Immunodeficiencies, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Nima Rezaei
- Research Center for Immunodeficiencies, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran; Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran; Cancer Immunology Project (CIP), Universal Scientific Education and Research Network (USERN), Sheffield, UK.
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8
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Pine GM, Batugedara HM, Nair MG. Here, there and everywhere: Resistin-like molecules in infection, inflammation, and metabolic disorders. Cytokine 2018; 110:442-451. [PMID: 29866514 DOI: 10.1016/j.cyto.2018.05.014] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Revised: 05/13/2018] [Accepted: 05/15/2018] [Indexed: 02/07/2023]
Abstract
The Resistin-Like Molecules (RELM) α, β, and γ and their namesake, resistin, share structural and sequence homology but exhibit significant diversity in expression and function within their mammalian host. RELM proteins are expressed in a wide range of diseases, such as: microbial infections (eg. bacterial and helminth), inflammatory diseases (eg. asthma, fibrosis) and metabolic disorders (eg. diabetes). While the expression pattern and molecular regulation of RELM proteins are well characterized, much controversy remains over their proposed functions, with evidence of host-protective and pathogenic roles. Moreover, the receptors for RELM proteins are unclear, although three receptors for resistin, decorin, adenylyl cyclase-associated protein 1 (CAP1), and Toll-like Receptor 4 (TLR4) have recently been proposed. In this review, we will first summarize the molecular regulation of the RELM gene family, including transcription regulation and tissue expression in humans and mouse disease models. Second, we will outline the function and receptor-mediated signaling associated with RELM proteins. Finally, we will discuss recent studies suggesting that, despite early misconceptions that these proteins are pathogenic, RELM proteins have a more nuanced and potentially beneficial role for the host in certain disease settings.
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Affiliation(s)
- Gabrielle M Pine
- Division of Biomedical Sciences, School of Medicine, University of California Riverside, Riverside, CA, United States
| | - Hashini M Batugedara
- Division of Biomedical Sciences, School of Medicine, University of California Riverside, Riverside, CA, United States
| | - Meera G Nair
- Division of Biomedical Sciences, School of Medicine, University of California Riverside, Riverside, CA, United States.
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Propheter DC, Chara AL, Harris TA, Ruhn KA, Hooper LV. Resistin-like molecule β is a bactericidal protein that promotes spatial segregation of the microbiota and the colonic epithelium. Proc Natl Acad Sci U S A 2017; 114:11027-11033. [PMID: 28973871 PMCID: PMC5651776 DOI: 10.1073/pnas.1711395114] [Citation(s) in RCA: 110] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The mammalian intestine is colonized by trillions of bacteria that perform essential metabolic functions for their hosts. The mutualistic nature of this relationship depends on maintaining spatial segregation between these bacteria and the intestinal epithelial surface. This segregation is achieved in part by the presence of a dense mucus layer at the epithelial surface and by the production of antimicrobial proteins that are secreted by epithelial cells into the mucus layer. Here, we show that resistin-like molecule β (RELMβ) is a bactericidal protein that limits contact between Gram-negative bacteria and the colonic epithelial surface. Mouse and human RELMβ selectively killed Gram-negative bacteria by forming size-selective pores that permeabilized bacterial membranes. In mice lacking RELMβ, Proteobacteria were present in the inner mucus layer and invaded mucosal tissues. Another RELM family member, human resistin, was also bactericidal, suggesting that bactericidal activity is a conserved function of the RELM family. Our findings thus identify the RELM family as a unique family of bactericidal proteins and show that RELMβ promotes host-bacterial mutualism by regulating the spatial segregation between the microbiota and the intestinal epithelium.
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Affiliation(s)
- Daniel C Propheter
- Department of Immunology, The University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Andrew L Chara
- Department of Immunology, The University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Tamia A Harris
- Department of Immunology, The University of Texas Southwestern Medical Center, Dallas, TX 75390
- Department of Dermatology, The University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Kelly A Ruhn
- Department of Immunology, The University of Texas Southwestern Medical Center, Dallas, TX 75390
| | - Lora V Hooper
- Department of Immunology, The University of Texas Southwestern Medical Center, Dallas, TX 75390;
- Howard Hughes Medical Institute, The University of Texas Southwestern Medical Center, Dallas, TX 75390
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