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Dietary antigens suppress the proliferation of type 2 innate lymphoid cells by restraining homeostatic IL-25 production. Sci Rep 2022; 12:7443. [PMID: 35523930 PMCID: PMC9076687 DOI: 10.1038/s41598-022-11466-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2021] [Accepted: 04/25/2022] [Indexed: 11/16/2022] Open
Abstract
Dietary antigens affect the adaptive immunity of the host by inducing regulatory T cells and IgE-producing B cells. However, their roles in innate immune compartments such as innate lymphoid cells (ILCs) and intestinal epithelial cells (IECs) are unclear. Here, using antigen-free (AF) mice, which are germ-free (GF) mice fed with amino-acid-based diet, we found dietary proteins suppress the development of GATA-3-expressing ILC2s independent of the adaptive immune cells. These cells produce more type 2 cytokines and upregulated proliferation and activation markers such as Ki-67, CD69, and CD25. With this, AF mice had increased expressions of tuft cell-specific transcripts such as Il25, Il33, Dclk1, Trpm5, and Pou2f3 in IECs. Accordingly, expanded ILC2s upregulated IL-17RB, a receptor of IL-25, and their proliferation was blocked by IL-25 neutralizing or IL-17RB blocking antibodies. These results suggest a new dialogue between dietary antigens, IECs, and ILCs in which dietary antigens suppress ILC2 activation and proliferation by restraining homeostatic IL-25 production, potentially limiting type 2 immunity by food antigens.
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2
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Oemcke LA, Anderson RC, Altermann E, Roy NC, McNabb WC. The Role of Segmented Filamentous Bacteria in Immune Barrier Maturation of the Small Intestine at Weaning. Front Nutr 2021; 8:759137. [PMID: 34869529 PMCID: PMC8637878 DOI: 10.3389/fnut.2021.759137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Accepted: 10/25/2021] [Indexed: 11/24/2022] Open
Abstract
The microbiological, physical, chemical, and immunological barriers of the gastrointestinal tract (GIT) begin developing in utero and finish maturing postnatally. Maturation of these barriers is essential for the proper functioning of the GIT. Maturation, particularly of the immunological barrier, involves stimulation by bacteria. Segmented filamentous bacteria (SFB) which are anaerobic, spore-forming commensals have been linked to immune activation. The presence and changes in SFB abundance have been positively correlated to immune markers (cytokines and immunoglobulins) in the rat ileum and stool samples, pre- and post-weaning. The abundance of SFB in infant stool increases from 6 months, peaks around 12 months and plateaus 25 months post-weaning. Changes in SFB abundance at these times correlate positively and negatively with the production of interleukin 17 (IL 17) and immunoglobulin A (IgA), respectively, indicating involvement in immune function and maturation. Additionally, the peak in SFB abundance when a human milk diet was complemented by solid foods hints at a diet effect. SFB genome analysis revealed enzymes involved in metabolic pathways for survival, growth and development, host mucosal attachment and substrate acquisition. This narrative review discusses the current knowledge of SFB and their suggested effects on the small intestine immune system. Referencing the published genomes of rat and mouse SFB, the use of food substrates to modulate SFB abundance is proposed while considering their effects on other microbes. Changes in the immune response caused by the interaction of food substrate with SFB may provide insight into their role in infant immunological barrier maturation.
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Affiliation(s)
- Linda A Oemcke
- Riddet Institute, Massey University, Palmerston North, New Zealand.,School of Food and Advanced Technology, Massey University, Palmerston North, New Zealand.,Smart Foods Innovation Centre of Excellence, AgResearch, Palmerston North, New Zealand
| | - Rachel C Anderson
- Riddet Institute, Massey University, Palmerston North, New Zealand.,Smart Foods Innovation Centre of Excellence, AgResearch, Palmerston North, New Zealand
| | - Eric Altermann
- Riddet Institute, Massey University, Palmerston North, New Zealand.,Consumer Interface Innovation Centre of Excellence, AgResearch, Palmerston North, New Zealand.,High-Value Nutrition National Science Challenge, Auckland, New Zealand
| | - Nicole C Roy
- Riddet Institute, Massey University, Palmerston North, New Zealand.,High-Value Nutrition National Science Challenge, Auckland, New Zealand.,Department of Human Nutrition, University of Otago, Dunedin, New Zealand
| | - Warren C McNabb
- Riddet Institute, Massey University, Palmerston North, New Zealand.,High-Value Nutrition National Science Challenge, Auckland, New Zealand
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3
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Lee SK. Let Them Flourish for the First Weeks and Suffer Less Bifidobacteria carrying beneficial genes utilizing human milk oligosaccharides (HMOs) help develop a healthy immune system in breastfed babies. Mol Cells 2021; 44:706-709. [PMID: 34711688 PMCID: PMC8560587 DOI: 10.14348/molcells.2021.0246] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2021] [Accepted: 10/08/2021] [Indexed: 11/27/2022] Open
Affiliation(s)
- Sun-Kyung Lee
- Department of Life Sciences, Research Institute for Natural Sciences, College of Natural Sciences, Hanyang University, Seoul 04763, Korea
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4
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Zhao S, Zhu L, Feng W, Zhang L, Chen DD, Hu YC, Shen H. MicroRNA-602 prevents the development of inflammatory bowel diseases in a microbiota-dependent manner. Exp Ther Med 2021; 22:1373. [PMID: 34659519 PMCID: PMC8515559 DOI: 10.3892/etm.2021.10808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2019] [Accepted: 03/10/2020] [Indexed: 11/29/2022] Open
Abstract
Inflammatory bowel diseases (IBD) are a group of chronic disorders occurring in the intestinal tract. Previous studies demonstrated that genetics and microbiota play critical roles in the pathogenesis of IBD. Discoveries of genes that may regulate the homeostasis of gut microbiota and pathogenesis of IBD have the potential to provide new therapeutic targets for IBD treatment. The results suggested that the expression level of microRNA (miR)-602 is negatively related to the development of IBD, and that miR-602 overexpression in mice may prevent inflammation and intestinal barrier injuries in dextran sulfate sodium (DSS)-induced IBD mice. It was also found that the microbiota is important for miR-602-mediated prevention of IBD, as the inhibitory effect of miR-602 was lost when the microbiota was depleted using antibiotics. Furthermore, co-housing or adoptive transfer of microbiota from miR-602 could attenuate the pathogenesis of IBD. In addition, it was demonstrated that miR-602 could target tumor necrosis factor receptor-associated factor 6 (TRAF6) in intestinal epithelial cells. Collectively, the present results suggest that miR-602 plays a protective role in DSS-induced IBD by targeting TRAF6 in a microbiota-dependent manner.
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Affiliation(s)
- Song Zhao
- Department of Gastroenterology, Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, Jiangsu 210029, P.R. China
| | - Lei Zhu
- Department of Gastroenterology, Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, Jiangsu 210029, P.R. China
| | - Wan Feng
- Department of Gastroenterology, Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, Jiangsu 210029, P.R. China
| | - Lu Zhang
- Department of Gastroenterology, Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, Jiangsu 210029, P.R. China
| | - Dan-Dan Chen
- Department of Gastroenterology, Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, Jiangsu 210029, P.R. China
| | - Yu-Cui Hu
- Department of Gastroenterology, Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, Jiangsu 210029, P.R. China
| | - Hong Shen
- Department of Gastroenterology, Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, Jiangsu 210029, P.R. China
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5
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Kononova S, Litvinova E, Vakhitov T, Skalinskaya M, Sitkin S. Acceptive Immunity: The Role of Fucosylated Glycans in Human Host-Microbiome Interactions. Int J Mol Sci 2021; 22:ijms22083854. [PMID: 33917768 PMCID: PMC8068183 DOI: 10.3390/ijms22083854] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 04/04/2021] [Accepted: 04/05/2021] [Indexed: 02/07/2023] Open
Abstract
The growth in the number of chronic non-communicable diseases in the second half of the past century and in the first two decades of the new century is largely due to the disruption of the relationship between the human body and its symbiotic microbiota, and not pathogens. The interaction of the human immune system with symbionts is not accompanied by inflammation, but is a physiological norm. This is achieved via microbiota control by the immune system through a complex balance of pro-inflammatory and suppressive responses, and only a disturbance of this balance can trigger pathophysiological mechanisms. This review discusses the establishment of homeostatic relationships during immune system development and intestinal bacterial colonization through the interaction of milk glycans, mucins, and secretory immunoglobulins. In particular, the role of fucose and fucosylated glycans in the mechanism of interactions between host epithelial and immune cells is discussed.
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Affiliation(s)
- Svetlana Kononova
- Department of Microbiology, State Research Institute of Highly Pure Biopreparations, 197110 St. Petersburg, Russia; (T.V.); (M.S.); (S.S.)
- Institute of Protein Research, Russian Academy of Sciences, 142290 Pushchino, Russia
- Correspondence:
| | - Ekaterina Litvinova
- Scientific-Research Institute of Neurosciences and Medicine, 630117 Novosibirsk, Russia;
- Siberian Federal Scientific Center of Agro-BioTechnologies, Russian Academy of Sciences, Krasnoobsk, 633501 Novosibirsk, Russia
| | - Timur Vakhitov
- Department of Microbiology, State Research Institute of Highly Pure Biopreparations, 197110 St. Petersburg, Russia; (T.V.); (M.S.); (S.S.)
| | - Maria Skalinskaya
- Department of Microbiology, State Research Institute of Highly Pure Biopreparations, 197110 St. Petersburg, Russia; (T.V.); (M.S.); (S.S.)
- Department of Internal Diseases, Gastroenterology and Dietetics, North-Western State Medical University Named after I.I. Mechnikov, 191015 St. Petersburg, Russia
| | - Stanislav Sitkin
- Department of Microbiology, State Research Institute of Highly Pure Biopreparations, 197110 St. Petersburg, Russia; (T.V.); (M.S.); (S.S.)
- Department of Internal Diseases, Gastroenterology and Dietetics, North-Western State Medical University Named after I.I. Mechnikov, 191015 St. Petersburg, Russia
- Institute of Perinatology and Pediatrics, Almazov National Medical Research Centre, 197341 St. Petersburg, Russia
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6
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Oemcke LA, Anderson RC, Rakonjac J, McNabb WC, Roy NC. Whole tissue homogenization preferable to mucosal scraping in determining the temporal profile of segmented filamentous bacteria in the ileum of weanling rats. Access Microbiol 2021; 3:000218. [PMID: 34151170 PMCID: PMC8209713 DOI: 10.1099/acmi.0.000218] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 03/04/2021] [Indexed: 01/12/2023] Open
Abstract
Segmented filamentous bacteria (SFB) are thought to play a role in small intestine immunological maturation. Studies in weanling mice have shown a positive correlation between ileal SFB abundance and plasma and faecal interleukin 17 (IL-17) and immunoglobulin A (IgA) concentrations. Although the first observation of SFB presence was reported in rats, most studies use mice. The size of the mouse ileum is a limitation whereas the rat could be a suitable alternative for sufficient samples. Changes in SFB abundance over time in rats were hypothesized to follow the pattern reported in mice and infants. We characterized the profile of SFB colonization in the ileum tissue and contents and its correlation with two immune markers of gastrointestinal tract (GIT) maturation. We also compared two published ileum collection techniques to determine which yields data on SFB abundance with least variability. Whole ileal tissue and ileal mucosal scrapings were collected from 20- to 32-day-old Sprague-Dawley rats. SFB abundance was quantified from proximal, middle and distal ileal tissues, contents and faeces by quantitative PCR using SFB-specific primers. Antibody-specific ELISAs were used to determine IL-17 and IgA concentrations. Significant differences in SFB abundance were observed from whole and scraped tissues peaking at day 22. Variability in whole ileum data was less, favouring it as a better collection technique. A similar pattern of SFB abundance was observed in ileum contents and faeces peaking at day 24, suggesting faeces can be a proxy for ileal SFB abundance. SFB abundance at day 26 was higher in females than males across all samples. There were significant differences in IgA concentration between days 20, 30 and 32 and none in IL-17 concentration, which was different from reports in mice and infants.
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Affiliation(s)
- Linda A. Oemcke
- Riddet Institute, Massey University, Palmerston North, New Zealand
- School of Food and Advanced Technology, Massey University, Palmerston North, New Zealand
- AgResearch, Grasslands Research Centre, Palmerston North, New Zealand
| | - Rachel C. Anderson
- Riddet Institute, Massey University, Palmerston North, New Zealand
- AgResearch, Grasslands Research Centre, Palmerston North, New Zealand
| | - Jasna Rakonjac
- School of Fundamental Sciences, Massey University, Palmerston North, New Zealand
| | - Warren C. McNabb
- Riddet Institute, Massey University, Palmerston North, New Zealand
- High-Value Nutrition National Science Challenge, Auckland, New Zealand
| | - Nicole C. Roy
- Riddet Institute, Massey University, Palmerston North, New Zealand
- High-Value Nutrition National Science Challenge, Auckland, New Zealand
- Department of Human Nutrition, University of Otago, Dunedin, New Zealand
- Liggins Institute, University of Auckland, Auckland, New Zealand
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7
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Li M, Wang X, Lin X, Bian X, Jing R, Frelinger A, Zhang A. Comparison and Analysis of Gut Microbiota in Children With IgA Vasculitis With Different Clinical Symptoms. Front Pediatr 2021; 9:800677. [PMID: 35071141 PMCID: PMC8778574 DOI: 10.3389/fped.2021.800677] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 11/18/2021] [Indexed: 11/16/2022] Open
Abstract
Background: Henoch-Schönlein purpura, now called immunoglobulin A (IgA) vasculitis, is a common autoimmune disease in children, its association with gut microbiota composition remains unknown. Methods: The collected cases were divided into three groups: G1 group of simple skin type, G2 group with no digestive tract expression, G3 group of mixed digestive tract, and C group of healthy children. The fecal samples of each group of children were collected and the sequencing data was processed and analyzed. The dilution curve reflected the reasonableness of the amount of sequencing data. Results: The number of species composition sequences in the G1, G2 and G3 groups was lower than that in the C group, especially for the G2 and G3 groups. The four most abundant bacteria were Bacteroidetes, Firmicutes, Proteobacteria and Actinobacteria. The relative abundance of Proteobacteria in the G2 and G3 groups was significantly higher than that in the G1 and C groups, while the relative abundance of Actinobacteria was significantly reduced, and the relative abundance of Actinobacteria in the G1 group was lower than that in the C group. Principal component analysis of the UPGMA clustering tree and each group of samples showed that the microbial community composition of the same group of samples was similar. Conclusions: The abundance of intestinal microbes in children with IgA vasculitis is lower than in normal children. Bacteroidetes, Firmicutes, Proteobacteria and Actinobacteria are the four most abundant bacteria in the intestinal flora of children. Proteobacteria and Actinobacteria are associated with organ involvement in IgA vasculitis.
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Affiliation(s)
- Meng Li
- Department of Pediatrics, Qilu Hospital of Shandong University, Jinan, China
| | - Xiaoming Wang
- Department of Pediatrics, Qilu Hospital of Shandong University, Jinan, China
| | - Xingjie Lin
- Department of Pediatrics, Qilu Hospital of Shandong University, Jinan, China
| | - Xiuju Bian
- Department of Pediatrics, The Fifth People's Hospital of Jinan, Jinan, China
| | - Rui Jing
- Department of Pediatrics, The People's Hospital of Weifang, Weifang, China
| | - Andrew Frelinger
- Dana-Farber/Boston Children's Cancer and Blood Disorders Center, Harvard Medical School, Boston, MA, United States
| | - Aijun Zhang
- Department of Pediatrics, Qilu Hospital of Shandong University, Jinan, China
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8
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Hathaway-Schrader JD, Poulides NA, Carson MD, Kirkpatrick JE, Warner AJ, Swanson BA, Taylor EV, Chew ME, Reddy SV, Liu B, Westwater C, Novince CM. Specific Commensal Bacterium Critically Regulates Gut Microbiota Osteoimmunomodulatory Actions During Normal Postpubertal Skeletal Growth and Maturation. JBMR Plus 2020; 4:e10338. [PMID: 32161843 PMCID: PMC7059828 DOI: 10.1002/jbm4.10338] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2019] [Revised: 01/06/2020] [Accepted: 01/07/2020] [Indexed: 12/19/2022] Open
Abstract
The commensal gut microbiota critically regulates immunomodulatory processes that influence normal skeletal growth and maturation. However, the influence of specific microbes on commensal gut microbiota osteoimmunoregulatory actions is unknown. We have shown previously that the commensal gut microbiota enhances TH17/IL17A immune response effects in marrow and liver that have procatabolic/antianabolic actions in the skeleton. Segmented filamentous bacteria (SFB), a specific commensal gut bacterium within phylum Firmicutes, potently induces TH17/IL17A‐mediated immunity. The study purpose was to delineate the influence of SFB on commensal gut microbiota immunomodulatory actions regulating normal postpubertal skeletal development. Two murine models were utilized: SFB‐monoassociated mice versus germ‐free (GF) mice and specific‐pathogen‐free (SPF) mice +/− SFB. SFB colonization was validated by 16S rDNA analysis, and SFB‐induced TH17/IL17A immunity was confirmed by upregulation of Il17a in ileum and IL17A in serum. SFB‐colonized mice had an osteopenic trabecular bone phenotype, which was attributed to SFB actions suppressing osteoblastogenesis and enhancing osteoclastogenesis. Intriguingly, SFB‐colonized mice had increased expression of proinflammatory chemokines and acute‐phase reactants in the liver. Lipocalin‐2 (LCN2), an acute‐phase reactant and antimicrobial peptide, was substantially elevated in the liver and serum of SFB‐colonized mice, which supports the notion that SFB regulation of commensal gut microbiota osteoimmunomodulatory actions are mediated in part through a gut–liver–bone axis. Proinflammatory TH17 and TH1 cells were increased in liver‐draining lymph nodes of SFB‐colonized mice, which further substantiates that SFB osteoimmune‐response effects may be mediated through the liver. SFB‐induction of Il17a in the gut and Lcn2 in the liver resulted in increased circulating levels of IL17A and LCN2. Recognizing that IL17A and LCN2 support osteoclastogenesis/suppress osteoblastogenesis, SFB actions impairing postpubertal skeletal development appear to be mediated through immunomodulatory effects in both the gut and liver. This research reveals that specific microbes critically impact commensal gut microbiota immunomodulatory actions regulating normal postpubertal skeletal growth and maturation. © 2020 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.
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Affiliation(s)
- Jessica D Hathaway-Schrader
- Department of Oral Health Sciences College of Dental Medicine, Medical University of South Carolina Charleston SC USA.,Department of Pediatrics-Division of Endocrinology College of Medicine, Medical University of South Carolina Charleston SC USA
| | - Nicole A Poulides
- Department of Oral Health Sciences College of Dental Medicine, Medical University of South Carolina Charleston SC USA.,Department of Pediatrics-Division of Endocrinology College of Medicine, Medical University of South Carolina Charleston SC USA
| | - Matthew D Carson
- Department of Oral Health Sciences College of Dental Medicine, Medical University of South Carolina Charleston SC USA.,Department of Pediatrics-Division of Endocrinology College of Medicine, Medical University of South Carolina Charleston SC USA
| | - Joy E Kirkpatrick
- Department of Oral Health Sciences College of Dental Medicine, Medical University of South Carolina Charleston SC USA.,Department of Drug Discovery & Biomedical Sciences College of Pharmacy, Medical University of South Carolina Charleston SC USA
| | - Amy J Warner
- Department of Oral Health Sciences College of Dental Medicine, Medical University of South Carolina Charleston SC USA.,Department of Pediatrics-Division of Endocrinology College of Medicine, Medical University of South Carolina Charleston SC USA
| | - Brooks A Swanson
- Department of Oral Health Sciences College of Dental Medicine, Medical University of South Carolina Charleston SC USA.,Department of Pediatrics-Division of Endocrinology College of Medicine, Medical University of South Carolina Charleston SC USA
| | - Eliza V Taylor
- Department of Oral Health Sciences College of Dental Medicine, Medical University of South Carolina Charleston SC USA
| | - Michael E Chew
- Department of Oral Health Sciences College of Dental Medicine, Medical University of South Carolina Charleston SC USA
| | - Sakamuri V Reddy
- Department of Pediatrics-Division of Endocrinology College of Medicine, Medical University of South Carolina Charleston SC USA
| | - Bei Liu
- Department of Microbiology and Immunology College of Medicine, Medical University of South Carolina Charleston SC USA
| | - Caroline Westwater
- Department of Oral Health Sciences College of Dental Medicine, Medical University of South Carolina Charleston SC USA.,Department of Microbiology and Immunology College of Medicine, Medical University of South Carolina Charleston SC USA
| | - Chad M Novince
- Department of Oral Health Sciences College of Dental Medicine, Medical University of South Carolina Charleston SC USA.,Department of Pediatrics-Division of Endocrinology College of Medicine, Medical University of South Carolina Charleston SC USA
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9
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Gut Microbiota Modulation on Intestinal Mucosal Adaptive Immunity. J Immunol Res 2019; 2019:4735040. [PMID: 31687412 PMCID: PMC6794961 DOI: 10.1155/2019/4735040] [Citation(s) in RCA: 69] [Impact Index Per Article: 13.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 08/05/2019] [Indexed: 02/07/2023] Open
Abstract
The mammalian intestine harbors a remarkable number of microbes and their components and metabolites, which are fundamental for the instigation and development of the host immune system. The intestinal innate and adaptive immunity coordinate and interact with the symbionts contributing to the intestinal homeostasis through establishment of a mutually beneficial relationship by tolerating to symbiotic microbiota and retaining the ability to exert proinflammatory response towards invasive pathogens. Imbalance between the intestinal immune system and commensal organisms disrupts the intestinal microbiological homeostasis, leading to microbiota dysbiosis, compromised integrity of the intestinal barrier, and proinflammatory immune responses towards symbionts. This, in turn, exacerbates the degree of the imbalance. Intestinal adaptive immunity plays a critical role in maintaining immune tolerance towards symbionts and the integrity of intestinal barrier, while the innate immune system regulates the adaptive immune responses to intestinal commensal bacteria. In this review, we will summarize recent findings on the effects and mechanisms of gut microbiota on intestinal adaptive immunity and the plasticity of several immune cells under diverse microenvironmental settings.
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