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Clevenger MH, Wei C, Karami AL, Tsikretsis LE, Carlson DA, Pandolfino JE, Gonsalves N, Winter DR, Whelan KA, Tétreault MP. Esophageal epithelial Ikkβ deletion promotes eosinophilic esophagitis in experimental allergy mouse model. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.05.602313. [PMID: 39026724 PMCID: PMC11257468 DOI: 10.1101/2024.07.05.602313] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
Background Eosinophilic esophagitis (EoE) is a chronic T helper type 2 (Th2)-associated inflammatory disorder triggered by food allergens, resulting in esophageal dysfunction through edema, fibrosis, and tissue remodeling. The role of epithelial remodeling in EoE pathogenesis is critical but not fully understood. Objective To investigate the role of epithelial IKKβ/NFκB signaling in EoE pathogenesis using a mouse model with conditional Ikk β knockout in esophageal epithelial cells ( Ikk β EEC-KO ). Methods EoE was induced in Ikkβ EEC-KO mice through skin sensitization with MC903/Ovalbumin (OVA) followed by intraesophageal OVA challenge. Histological and transcriptional analyses were performed to assess EoE features. Single-cell RNA sequencing (scRNA-seq) was used to profile esophageal mucosal cell populations and gene expression changes. Results Ikkβ EEC-KO /EoE mice exhibited hallmark EoE features, including eosinophil infiltration, intraepithelial eosinophils, microabscesses, basal cell hyperplasia, and lamina propria remodeling. RNA-seq revealed significant alterations in IKKβ/NFκB signaling pathways, with decreased expression of RELA and increased expression of IKKβ negative regulators. scRNA- seq analyses identified disrupted epithelial differentiation and barrier integrity, alongside increased type 2 immune responses and peptidase activity. Conclusion Our study demonstrates that loss of epithelial IKKβ signaling exacerbates EoE pathogenesis, highlighting the critical role of this pathway in maintaining epithelial homeostasis and preventing allergic inflammation. The Ikkβ EEC-KO /EoE mouse model closely mirrors human EoE, providing a valuable tool for investigating disease mechanisms and therapeutic targets. This model can facilitate the development of strategies to prevent chronic inflammation and tissue remodeling in EoE. Key Messages Critical Role of Epithelial IKKβ/NFκB Signaling: Loss of this signaling exacerbates EoE, causing eosinophil infiltration, basal cell hyperplasia, and tissue remodeling, highlighting its importance in esophageal health.Molecular Insights and Therapeutic Targets: scRNA-seq identified disrupted epithelial differentiation, barrier integrity, and enhanced type 2 immune responses, suggesting potential therapeutic targets for EoE. Relevance of the Ikkβ EEC-KO /EoE Mouse Model: This model replicates human EoE features, making it a valuable tool for studying EoE mechanisms and testing treatments, which can drive the development of effective therapies. Capsule Summary This study reveals the crucial role of epithelial IKKβ/NFκB signaling in EoE, providing insights into disease mechanisms and potential therapeutic targets, highly relevant for advancing clinical management of EoE.
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Speir M, Djajawi TM, Conos SA, Tye H, Lawlor KE. Targeting RIP Kinases in Chronic Inflammatory Disease. Biomolecules 2021; 11:biom11050646. [PMID: 33924766 PMCID: PMC8146010 DOI: 10.3390/biom11050646] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 04/21/2021] [Accepted: 04/22/2021] [Indexed: 02/08/2023] Open
Abstract
Chronic inflammatory disorders are characterised by aberrant and exaggerated inflammatory immune cell responses. Modes of extrinsic cell death, apoptosis and necroptosis, have now been shown to be potent drivers of deleterious inflammation, and mutations in core repressors of these pathways underlie many autoinflammatory disorders. The receptor-interacting protein (RIP) kinases, RIPK1 and RIPK3, are integral players in extrinsic cell death signalling by regulating the production of pro-inflammatory cytokines, such as tumour necrosis factor (TNF), and coordinating the activation of the NOD-like receptor protein 3 (NLRP3) inflammasome, which underpin pathological inflammation in numerous chronic inflammatory disorders. In this review, we firstly give an overview of the inflammatory cell death pathways regulated by RIPK1 and RIPK3. We then discuss how dysregulated signalling along these pathways can contribute to chronic inflammatory disorders of the joints, skin, and gastrointestinal tract, and discuss the emerging evidence for targeting these RIP kinases in the clinic.
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Affiliation(s)
- Mary Speir
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, VIC 3168, Australia; (M.S.); (T.M.D.); (S.A.C.); (H.T.)
- Department of Molecular and Translational Science, Monash University, Clayton, VIC 3168, Australia
| | - Tirta M. Djajawi
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, VIC 3168, Australia; (M.S.); (T.M.D.); (S.A.C.); (H.T.)
- Department of Molecular and Translational Science, Monash University, Clayton, VIC 3168, Australia
| | - Stephanie A. Conos
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, VIC 3168, Australia; (M.S.); (T.M.D.); (S.A.C.); (H.T.)
- Department of Molecular and Translational Science, Monash University, Clayton, VIC 3168, Australia
| | - Hazel Tye
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, VIC 3168, Australia; (M.S.); (T.M.D.); (S.A.C.); (H.T.)
| | - Kate E. Lawlor
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, VIC 3168, Australia; (M.S.); (T.M.D.); (S.A.C.); (H.T.)
- Department of Molecular and Translational Science, Monash University, Clayton, VIC 3168, Australia
- Correspondence: ; Tel.: +61-85722700
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Guo CA, Ma L, Su XL, Wang YZ, Zhen LL, Zhang B, An H, Liu HB. Esmolol inhibits inflammation and apoptosis in the intestinal tissue via the overexpression of NF-κB-p65 in the early stage sepsis rats. TURKISH JOURNAL OF GASTROENTEROLOGY 2020; 31:331-341. [PMID: 32412904 DOI: 10.5152/tjg.2020.19341] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND/AIMS Accumulating evidence reveals esmolol could protect the gut mucosa through the regulation of immune response and inflammation in patients with sepsis. However, its underlying mechanism is not fully understood. MATERIALS AND METHODS Diamine oxidase (DAO), intestinal fatty acid-binding protein (I-FABP), interleukin (IL)-6, and IL-10 in the plasma of rats were detected by ELISA assay. Western blotting was utilized to measure the expression levels of NF-kappa B-p65, Bcl-2, and cleaved caspase-3 in the intestinal tissues. The survival analysis was performed in each group. RESULTS The plasma levels of DAO and IL-10 levels were increased, whereas that of I-FABP and IL-6 were decreased in the sepsis rats after esmolol treatment, indicating that after the esmolol treatment, the intestinal inflammation and damages were remarkably reduced as compared to those in the normal saline treated sepsis rats. NF-κB-p65 and Bcl-2 were highly expressed, but cleaved caspase-3 showed lower expression in the esmolol treated groups. However, at the same time, we observed contrasting results in the normal saline treated group. Western blotting data indicated that the esmolol treatment inhibited the inflammation and apoptosis in the intestinal tissue due to the overexpression of NF-κB-p65 in the celiac sepsis rats. The survival analysis results indicate that the esmolol infusion should be used in the early stages sepsis rats. CONCLUSION Esmolol can suppress inflammation and apoptosis in the intestinal tissue via the overexpression of NF-kappa B-p65 in the early stage sepsis rats. kappa BEarly-stage use of esmolol might be an ideal treatment method for sepsis.
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Affiliation(s)
- Chang-An Guo
- Second Clinical Medical College, Lanzhou University, Gansu Province, China;First Aid Center, Lanzhou University Second Hospital, Gansu Province, China;Department of General Surgery, The 940th Hospital of Joint Logistics Support Force of Chinese People's Liberation Army, China
| | - Li Ma
- Intensive Care Unit, Lanzhou University Second Hospital, Gansu Province, China
| | - Xiao-Lu Su
- Department of Pathology, Lanzhou University Second Hospital, Gansu Province, China
| | - Ying-Zhen Wang
- Intensive Care Unit, Lanzhou University Second Hospital, Gansu Province, China
| | - Ling-Ling Zhen
- Intensive Care Unit, Lanzhou University Second Hospital, Gansu Province, China
| | - Bei Zhang
- Intensive Care Unit, Lanzhou University Second Hospital, Gansu Province, China
| | - Hong An
- Intensive Care Unit, Lanzhou University Second Hospital, Gansu Province, China
| | - Hong-Bin Liu
- Department of General Surgery, The 940th Hospital of Joint Logistics Support Force of Chinese People's Liberation Army, China
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Lee H, Lee DS, Chang KJ, Kim SH, Cheong SH. Ribose-Taurine Suppresses Inflammation Through NF-κB Regulation in Activated RAW 264.7 Macrophages. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2019; 1155:1057-1067. [PMID: 31468467 DOI: 10.1007/978-981-13-8023-5_87] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
Abstract
Ribose-taurine (Rib-T) suppressed the generation of inflammatory mediators and cytokines, such as nitric oxide (NO) and prostaglandin E2 (PGE2) through the inhibition of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) expressions in lipopolysaccharide (LPS)-stimulated RAW 264.7 macrophages. The production of tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β induced by LPS was effectively blocked by Rib-T. Moreover, the anti-inflammatory actions of Rib-T were involved in its inhibitory effects against the nuclear translocation of nuclear factor-kappa B (NF-κB) p65, and NF-κB DNA-binding activity. These results suggest that the anti-inflammatory action of Rib-T is associated with NF-κB regulation.
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Affiliation(s)
- Hwan Lee
- College of Pharmacy, Chosun University, Dong-gu, Gwangju, Republic of Korea
| | - Dong-Sung Lee
- College of Pharmacy, Chosun University, Dong-gu, Gwangju, Republic of Korea
| | - Kyung Ja Chang
- Department of Food and Nutrition, Inha University, Incheon, Republic of Korea
| | - Sung Hoon Kim
- Department of Chemistry, Konkuk University, Seoul, Republic of Korea
| | - Sun Hee Cheong
- Department of Marine Bio-Food Sciences, Chonnam National University, Yeosu, Republic of Korea
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Garcia-Carbonell R, Yao SJ, Das S, Guma M. Dysregulation of Intestinal Epithelial Cell RIPK Pathways Promotes Chronic Inflammation in the IBD Gut. Front Immunol 2019; 10:1094. [PMID: 31164887 PMCID: PMC6536010 DOI: 10.3389/fimmu.2019.01094] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Accepted: 04/29/2019] [Indexed: 12/22/2022] Open
Abstract
Crohn's disease (CD) and ulcerative colitis (UC) are common intestinal bowel diseases (IBD) characterized by intestinal epithelial injury including extensive epithelial cell death, mucosal erosion, ulceration, and crypt abscess formation. Several factors including activated signaling pathways, microbial dysbiosis, and immune deregulation contribute to disease progression. Although most research efforts to date have focused on immune cells, it is becoming increasingly clear that intestinal epithelial cells (IEC) are important players in IBD pathogenesis. Aberrant or exacerbated responses to how IEC sense IBD-associated microbes, respond to TNF stimulation, and regenerate and heal the injured mucosa are critical to the integrity of the intestinal barrier. The role of several genes and pathways in which single nucleotide polymorphisms (SNP) showed strong association with IBD has recently been studied in the context of IEC. In patients with IBD, it has been shown that the expression of specific dysregulated genes in IECs plays an important role in TNF-induced cell death and microbial sensing. Among them, the NF-κB pathway and its target gene TNFAIP3 promote TNF-induced and receptor interacting protein kinase (RIPK1)-dependent intestinal epithelial cell death. On the other hand, RIPK2 functions as a key signaling protein in host defense responses induced by activation of the cytosolic microbial sensors nucleotide-binding oligomerization domain-containing proteins 1 and 2 (NOD1 and NOD2). The RIPK2-mediated signaling pathway leads to the activation of NF-κB and MAP kinases that induce autophagy following infection. This article will review these dysregulated RIPK pathways in IEC and their role in promoting chronic inflammation. It will also highlight future research directions and therapeutic approaches involving RIPKs in IBD.
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Affiliation(s)
| | - Shih-Jing Yao
- Department of Pathology, University of California, San Diego, San Diego, CA, United States
| | - Soumita Das
- Department of Pathology, University of California, San Diego, San Diego, CA, United States
| | - Monica Guma
- Medicine, School of Medicine, University of California, San Diego, San Diego, CA, United States
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Bazacliu C, Neu J. Pathophysiology of Necrotizing Enterocolitis: An Update. Curr Pediatr Rev 2019; 15:68-87. [PMID: 30387398 DOI: 10.2174/1573396314666181102123030] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/08/2018] [Revised: 09/12/2018] [Accepted: 09/15/2018] [Indexed: 12/12/2022]
Abstract
NEC is a devastating disease that, once present, is very difficult to treat. In the absence of an etiologic treatment, preventive measures are required. Advances in decoding the pathophysiology of NEC are being made but a more comprehensive understanding is needed for the targeting of preventative strategies. A better definition of the disease as well as diagnostic criteria are needed to be able to specifically label a disease as NEC. Multiple environmental factors combined with host susceptibility appear to contribute to enhanced risks for developing this disease. Several different proximal pathways are involved, all leading to a common undesired outcome: Intestinal necrosis. The most common form of this disease appears to involve inflammatory pathways that are closely meshed with the intestinal microbiota, where a dysbiosis may result in dysregulated inflammation. The organisms present in the intestinal tract prior to the onset of NEC along with their diversity and functional capabilities are just beginning to be understood. Fulfillment of postulates that support causality for particular microorganisms is needed if bacteriotherapies are to be intelligently applied for the prevention of NEC. Identification of molecular effector pathways that propagate inflammation, understanding of, even incipient role of genetic predisposition and of miRNAs may help solve the puzzle of this disease and may bring the researchers closer to finding a treatment. Despite recent progress, multiple limitations of the current animal models, difficulties related to studies in humans, along with the lack of a "clear" definition will continue to make it a very challenging disease to decipher.
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Affiliation(s)
- Catalina Bazacliu
- Department of Pediatrics, Division of Neonatology, University of Florida, FL, United States
| | - Josef Neu
- Department of Pediatrics, Division of Neonatology, University of Florida, FL, United States
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Chen L, Mongan M, Meng Q, Wang Q, Kao W, Xia Y. Corneal Wound Healing Requires IKB kinase β Signaling in Keratocytes. PLoS One 2016; 11:e0151869. [PMID: 26987064 PMCID: PMC4795706 DOI: 10.1371/journal.pone.0151869] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2015] [Accepted: 03/04/2016] [Indexed: 11/19/2022] Open
Abstract
IkB kinase β (IKKβ) is a key signaling kinase for inflammatory responses, but it also plays diverse cell type-specific roles that are not yet fully understood. Here we investigated the role of IKKβ in the cornea using IkkβΔCS mice in which the Ikkβ gene was specifically deleted in the corneal stromal keratocytes. The IkkβΔCS corneas had normal morphology, transparency and thickness; however, they did not heal well from mild alkali burn injury. In contrast to the IkkβF/F corneas that restored transparency in 2 weeks after injury, over 50% of the IkkβΔCS corneas failed to fully recover. They instead developed recurrent haze with increased stromal thickness, severe inflammation and apoptosis. This pathogenesis correlated with sustained myofibroblast transformation with increased α smooth muscle actin (α-SMA) expression, higher levels of senescence β-Gal activity and scar tissue formation at the late stage of wound healing. In addition, the IkkβΔCS corneas displayed elevated expression of hemo-oxygenase-1 (HO-1), a marker of oxidative stress, and activation of stress signaling pathways with increased JNK, c-Jun and SMAD2/3 phosphorylation. These data suggest that IKKβ in keratocytes is required to repress oxidative stress and attenuate fibrogenesis and senescence in corneal wound healing.
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Affiliation(s)
- Liang Chen
- Department of Environmental Health and Center of Environmental Genetics, University of Cincinnati Medical Center, Cincinnati, Ohio, 45267–0056, United States of America
| | - Maureen Mongan
- Department of Environmental Health and Center of Environmental Genetics, University of Cincinnati Medical Center, Cincinnati, Ohio, 45267–0056, United States of America
| | - Qinghang Meng
- Department of Environmental Health and Center of Environmental Genetics, University of Cincinnati Medical Center, Cincinnati, Ohio, 45267–0056, United States of America
| | - Qin Wang
- Department of Environmental Health and Center of Environmental Genetics, University of Cincinnati Medical Center, Cincinnati, Ohio, 45267–0056, United States of America
| | - Winston Kao
- Department of Ophthalmology, University of Cincinnati Medical Center, Cincinnati, Ohio, 45267–0056, United States of America
| | - Ying Xia
- Department of Environmental Health and Center of Environmental Genetics, University of Cincinnati Medical Center, Cincinnati, Ohio, 45267–0056, United States of America
- * E-mail:
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Böhringer M, Pohlers S, Schulze S, Albrecht-Eckardt D, Piegsa J, Weber M, Martin R, Hünniger K, Linde J, Guthke R, Kurzai O. Candida albicans infection leads to barrier breakdown and a MAPK/NF-κB mediated stress response in the intestinal epithelial cell line C2BBe1. Cell Microbiol 2016; 18:889-904. [PMID: 26752615 DOI: 10.1111/cmi.12566] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Revised: 12/04/2015] [Accepted: 12/20/2015] [Indexed: 12/15/2022]
Abstract
Intestinal epithelial cells (IEC) form a tight barrier to the gut lumen. Paracellular permeability of the intestinal barrier is regulated by tight junction proteins and can be modulated by microorganisms and other stimuli. The polymorphic fungus Candida albicans, a frequent commensal of the human mucosa, has the capacity of traversing this barrier and establishing systemic disease within the host. Infection of polarized C2BBe1 IEC with wild-type C. albicans led to a transient increase of transepithelial electric resistance (TEER) before subsequent barrier disruption, accompanied by a strong decline of junctional protein levels and substantial, but considerably delayed cytotoxicity. Time-resolved microarray-based transcriptome analysis of C. albicans challenged IEC revealed a prominent role of NF-κB and MAPK signalling pathways in the response to infection. Hence, we inferred a gene regulatory network based on differentially expressed NF-κB and MAPK pathway components and their predicted transcriptional targets. The network model predicted activation of GDF15 by NF-κB was experimentally validated. Furthermore, inhibition of NF-κB activation in C. albicans infected C2BBe1 cells led to enhanced cytotoxicity in the epithelial cells. Taken together our study identifies NF-κB activation as an important protective signalling pathway in the response of epithelial cells to C. albicans.
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Affiliation(s)
- Michael Böhringer
- Septomics Research Centre, Friedrich Schiller University and Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Jena, Germany
| | - Susann Pohlers
- Septomics Research Centre, Friedrich Schiller University and Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Jena, Germany
| | - Sylvie Schulze
- Research Group Systems Biology and Bioinformatics, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Jena, Germany
| | | | - Judith Piegsa
- Septomics Research Centre, Friedrich Schiller University and Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Jena, Germany
| | - Michael Weber
- Septomics Research Centre, Friedrich Schiller University and Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Jena, Germany
| | - Ronny Martin
- Septomics Research Centre, Friedrich Schiller University and Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Jena, Germany
| | - Kerstin Hünniger
- Septomics Research Centre, Friedrich Schiller University and Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Jena, Germany
| | - Jörg Linde
- Research Group Systems Biology and Bioinformatics, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Jena, Germany
| | - Reinhard Guthke
- Research Group Systems Biology and Bioinformatics, Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Jena, Germany
| | - Oliver Kurzai
- Septomics Research Centre, Friedrich Schiller University and Leibniz Institute for Natural Product Research and Infection Biology - Hans Knöll Institute, Jena, Germany.,German National Reference Center for Invasive Fungal Infections, Hans Knöll Institute, Jena, Germany
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Wu NL, Huang DY, Tsou HN, Lin YC, Lin WW. Syk Mediates IL−17-Induced CCL20 Expression by Targeting Act1-Dependent K63-Linked Ubiquitination of TRAF6. J Invest Dermatol 2015; 135:490-498. [DOI: 10.1038/jid.2014.383] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 08/19/2014] [Accepted: 08/22/2014] [Indexed: 12/21/2022]
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Clostridium difficile-induced colitis in mice is independent of leukotrienes. Anaerobe 2014; 30:90-8. [PMID: 25230329 DOI: 10.1016/j.anaerobe.2014.09.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 09/04/2014] [Accepted: 09/07/2014] [Indexed: 02/03/2023]
Abstract
Clostridium difficile is the major cause of antibiotic-associated diarrhea and pseudomembranous colitis in healthcare settings. However, the host factors involved in the intestinal inflammatory response and pathogenesis of C. difficile infection (CDI) are largely unknown. Here we investigated the role of leukotrienes (LTs), a group of pro-inflammatory lipid mediators, in CDI. Notably, the neutrophil chemoattractant LTB4, but not cysteinyl (cys) LTs, was induced in the intestine of C57BL/6 mice infected with either C. difficile strain VPI 10463 or strain 630. Genetic or pharmacological ablation of LT production did not ameliorate C. difficile colitis or clinical signs of disease in infected mice. Histological analysis demonstrated that intestinal neutrophilic inflammation, edema and tissue damage in mice during acute and severe CDI were not modulated in the absence of LTs. In addition, CDI induced a burst of cytokines in the intestine of infected mice in a LT-independent manner. Serum levels of anti-toxin A immunoglobulin (Ig) G levels were also not modulated by endogenous LTs. Collectively, our results do not support a role for LTs in modulating host susceptibility to CDI in mice.
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Boonma P, Spinler JK, Venable SF, Versalovic J, Tumwasorn S. Lactobacillus rhamnosus L34 and Lactobacillus casei L39 suppress Clostridium difficile-induced IL-8 production by colonic epithelial cells. BMC Microbiol 2014; 14:177. [PMID: 24989059 PMCID: PMC4094603 DOI: 10.1186/1471-2180-14-177] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 06/18/2014] [Indexed: 01/01/2023] Open
Abstract
Background Clostridium difficile is the main cause of hospital-acquired diarrhea and colitis known as C. difficile-associated disease (CDAD).With increased severity and failure of treatment in CDAD, new approaches for prevention and treatment, such as the use of probiotics, are needed. Since the pathogenesis of CDAD involves an inflammatory response with a massive influx of neutrophils recruited by interleukin (IL)-8, this study aimed to investigate the probiotic effects of Lactobacillus spp. on the suppression of IL-8 production in response to C. difficile infection. Results We screened Lactobacillus conditioned media from 34 infant fecal isolates for the ability to suppress C. difficile-induced IL-8 production from HT-29 cells. Factors produced by two vancomycin-resistant lactobacilli, L. rhamnosus L34 (LR-L34) and L.casei L39 (LC-L39), suppressed the secretion and transcription of IL-8 without inhibiting C. difficile viability or toxin production. Conditioned media from LR-L34 suppressed the activation of phospho-NF-κB with no effect on phospho-c-Jun. However, LC-L39 conditioned media suppressed the activation of both phospho-NF-κB and phospho-c-Jun. Conditioned media from LR-L34 and LC-L39 also decreased the production of C. difficile-induced GM-CSF in HT-29 cells. Immunomodulatory factors present in the conditioned media of both LR-L34 and LC-L39 are heat-stable up to 100°C and > 100 kDa in size. Conclusions Our results suggest that L. rhamnosus L34 and L. casei L39 each produce factors capable of modulating inflammation stimulated by C. difficile. These vancomycin-resistant Lactobacillus strains are potential probiotics for treating or preventing CDAD.
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Affiliation(s)
| | | | | | | | - Somying Tumwasorn
- Department of Microbiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
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Beneficial Effects of Fractions of Nardostachys jatamansi on Lipopolysaccharide-Induced Inflammatory Response. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2014; 2014:837835. [PMID: 24795771 PMCID: PMC3985203 DOI: 10.1155/2014/837835] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/19/2013] [Revised: 02/28/2014] [Accepted: 03/03/2014] [Indexed: 12/02/2022]
Abstract
It has been previously shown that Nardostachys jatamansi (NJ) exhibits anti-inflammatory properties against lipopolysaccharide (LPS) challenges. However, the potency of NJ constituents against LPS-induced inflammatory responses has not been examined. In this present study, we determined which NJ extract fractions exhibit inhibitory effects against LPS-induced inflammatory responses. Among the NJ fractions, NJ-1, NJ-3, NJ-4, and NJ-6 inhibited LPS-induced production of NO. The NJ-3, NJ-4, and NJ-6 fractions also inhibited the production of cytokines, such as IL-1β, IL-6, and TNF-α. However, NJ-1, NJ-3, NJ-4, and NJ-6 showed differential inhibitory mechanisms against LPS-induced inflammatory responses. NJ-1, NJ-3, and NJ-4 inhibited LPS-induced activation of c-jun NH2-terminal kinase (JNK) and p38 but did not affect activation of extracellular signal-regulated kinase (ERK) or NF-κB. On the other hand, NJ-6 inhibited activation of MAPKs and NF-κB. In addition, in vivo experiments revealed that administration of NJ-1, NJ-3, NJ-4, and NJ-6 reduced LPS-induced endotoxin shock, with NJ-6 especially showing a marked protective effect. Taken together, these results provide the evidence for the potential of selective NJ fractions against LPS-induced inflammation. Thus, it will be advantageous to further isolate and determine single effective compounds from these potent fractions.
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Hunter CJ, De Plaen IG. Inflammatory signaling in NEC: Role of NF-κB, cytokines and other inflammatory mediators. ACTA ACUST UNITED AC 2013; 21:55-65. [PMID: 24388163 DOI: 10.1016/j.pathophys.2013.11.010] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- Catherine J Hunter
- Department of Surgery, Division of Pediatric Surgery, Northwestern University Feinberg School of Medicine, Ann and Robert H. Lurie Children's Hospital of Chicago, United States
| | - Isabelle G De Plaen
- Department of Pediatrics, Division of Neonatology, Northwestern University Feinberg School of Medicine, Ann and Robert H. Lurie Children's Hospital of Chicago, 225 E Chicago Avenue, Box 45, Chicago, IL 60611, United States.
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Inhibition of IKKβ in enterocytes exacerbates sepsis-induced intestinal injury and worsens mortality. Crit Care Med 2013; 41:e275-85. [PMID: 23939348 DOI: 10.1097/ccm.0b013e31828a44ed] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
OBJECTIVES Nuclear factor-κB is a critical regulator of cell-survival genes and the host inflammatory response. The purpose of this study was to investigate the role of enterocyte-specific NF-kB in sepsis through selective ablation of IkB kinase. DESIGN Prospective, randomized controlled study. SETTING Animal laboratories in university medical centers. SUBJECTS AND INTERVENTIONS Mice lacking functional NF-kB in their intestinal epithelium (Vil-Cre/Ikkβ) and wild-type mice were subjected to sham laparotomy or cecal ligation and puncture. Animals were killed at 24 hours or followed 7 days for survival. MEASUREMENTS AND MAIN RESULTS Septic wild-type mice had decreased villus length compared with sham mice, whereas villus atrophy was further exacerbated in septic Vil-Cre/Ikkβ mice. Sepsis induced an increase in intestinal epithelial apoptosis compared with sham mice, which was further exacerbated in Vil-Cre/Ikkβ mice. Sepsis induced intestinal hyperpermeability in wild-type mice compared with sham mice, which was further exacerbated in septic Vil-Cre/Ikkβ mice. This was associated with increased intestinal expression of claudin-2 in septic wild-type mice, which was further increased in septic Vil-Cre/Ikkβ mice. Both, pro-inflammatory and anti-inflammatory cytokines were increased in serum following cecal ligation and puncture, and interleukin 10 and monocyte chemoattractant protein-1 levels were higher in septic Vil-Cre/Ikkβ mice than in septic wild-type mice. All septic mice were bacteremic, but no differences in bacterial load were identified between wild-type and Vil-Cre/Ikkβ mice. To determine the functional significance of these results, animals were followed for survival. Septic wild-type mice had lower mortality than septic Vil-Cre/Ikkβ mice (47% vs 80%, p<0.05). Antitumor necrosis factor administration decreased intestinal apoptosis, permeability, and mortality in wild-type septic mice, and a similar improvement in intestinal integrity and survival were seen when antitumor necrosis factor was given to Vil-Cre/Ikkβ mice. CONCLUSIONS Enterocyte-specific NF-kB has a beneficial role in sepsis by partially preventing sepsis-induced increases in apoptosis and permeability, which are associated with worsening mortality.
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Ethanol Extract of Antrodia camphorata Grown on Germinated Brown Rice Suppresses Inflammatory Responses in Mice with Acute DSS-Induced Colitis. EVIDENCE-BASED COMPLEMENTARY AND ALTERNATIVE MEDICINE 2013; 2013:914524. [PMID: 23818935 PMCID: PMC3683464 DOI: 10.1155/2013/914524] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/07/2013] [Revised: 04/10/2013] [Accepted: 04/22/2013] [Indexed: 01/19/2023]
Abstract
The anti-inflammatory activity of Antrodia camphorata (AC) grown on germinated brown rice (CBR) extract was evaluated in vitro and in vivo. CBR suppressed the release of nitric oxide (NO) and prostaglandin (PG) E2 from lipopolysaccharide-(LPS-)stimulated RAW264.7 cells. CBR inhibited the level of inducible nitric oxide synthase (iNOS) and cyclooxygenase-(COX-)2 proteins, and it activated p38-MAPK, extracellular signal-related kinases (ERK), and NF-κB in LPS-stimulated RAW264.7 macrophages. LPS-induced tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) mRNA expression was reduced in CBR-treated RAW264.7 cells. In concert with in vitro data, CBR suppressed the levels of dextran-sulfate-sodium-(DSS-)induced iNOS and COX-2 proteins in the colon tissue. CBR treatment inhibited activated p38-MAPK, ERK, and NF-κB proteins in the colon tissue of DSS-induced mice. TNF-α and IL-6 mRNA expression was reduced in DSS+CBR-treated mice. The disease activity index and histological scores were significantly lower in CBR-treated mice (500 mg/kg/day) than in DSS-treated mice (P < 0.05 versus DSS). This is the first report of anti-inflammatory activity of CBR in DSS-induced acute colitis. These results suggest that CBR is a promising, potential agent for preventing acute colitis through the inhibition of NF-κB signaling and its upstream signaling molecules, including MAPKs.
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Abstract
The pathogenesis of necrotizing enterocolitis (NEC) is complex and its speed of progression is variable. To gain understanding of the disease, researchers have examined tissues resected from patients with NEC; however, as these are obtained at late stages of the disease, they do not yield clues about the early pathogenic events leading to NEC. Therefore, animal models are used and have helped identify a role for several mediators of the inflammatory network in NEC. In this article, we discuss the evidence for the role of these inflammatory mediators and conclude with a current unifying hypothesis regarding NEC pathogenesis.
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Affiliation(s)
- Isabelle G. De Plaen
- Associate Professor of Pediatrics, Department of Pediatrics, Division of Neonatology, Northwestern University Feinberg School of Medicine, Children’s Hospital of Chicago Research Center, Ann and Robert H. Lurie Children’s Hospital of Chicago, 225 E. Chicago Ave, Box 45, Chicago, IL 60611-2605, U.S.A., Tel: (773)-755-6379; fax: (312)-227-9758
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17
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Buret AG, Bhargava A. Modulatory mechanisms of enterocyte apoptosis by viral, bacterial and parasitic pathogens. Crit Rev Microbiol 2013; 40:1-17. [DOI: 10.3109/1040841x.2012.746952] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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18
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McAllister CS, Lakhdari O, Pineton de Chambrun G, Gareau MG, Broquet A, Lee GH, Shenouda S, Eckmann L, Kagnoff MF. TLR3, TRIF, and caspase 8 determine double-stranded RNA-induced epithelial cell death and survival in vivo. THE JOURNAL OF IMMUNOLOGY 2012; 190:418-27. [PMID: 23209324 DOI: 10.4049/jimmunol.1202756] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
TLR3 signaling is activated by dsRNA, a virus-associated molecular pattern. Injection of dsRNA into mice induced a rapid, dramatic, and reversible remodeling of the small intestinal mucosa with significant villus shortening. Villus shortening was preceded by increased caspase 3 and 8 activation and apoptosis of intestinal epithelial cells (IECs) located in the mid to upper villus with ensuing luminal fluid accumulation and diarrhea because of an increased secretory state. Mice lacking TLR3 or the adaptor molelcule TRIF mice were completely protected from dsRNA-induced IEC apoptosis, villus shortening, and diarrhea. dsRNA-induced apoptosis was independent of TNF signaling. Notably, NF-κB signaling through IκB kinase β protected crypt IECs but did not protect villus IECs from dsRNA-induced or TNF-induced apoptosis. dsRNA did not induce early caspase 3 activation with subsequent villus shortening in mice lacking caspase 8 in IECs but instead caused villus destruction with a loss of small intestinal surface epithelium and death. Consistent with direct activation of the TLR3-TRIF-caspase 8 signaling pathway by dsRNA in IECs, dsRNA-induced signaling of apoptosis was independent of non-TLR3 dsRNA signaling pathways, IL-15, TNF, IL-1, IL-6, IFN regulatory factor 3, type I IFN receptor, adaptive immunity, as well as dendritic cells, NK cells, and other hematopoietic cells. We conclude that dsRNA activation of the TLR3-TRIF-caspase 8 signaling pathway in IECs has a significant impact on the structure and function of the small intestinal mucosa and suggest signaling through this pathway has a host protective role during infection with viral pathogens.
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Intrarectal instillation of Clostridium difficile toxin A triggers colonic inflammation and tissue damage: development of a novel and efficient mouse model of Clostridium difficile toxin exposure. Infect Immun 2012; 80:4474-84. [PMID: 23045481 DOI: 10.1128/iai.00933-12] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
Clostridium difficile, a major cause of hospital-acquired diarrhea, triggers disease through the release of two toxins, toxin A (TcdA) and toxin B (TcdB). These toxins disrupt the cytoskeleton of the intestinal epithelial cell, increasing intestinal permeability and triggering the release of inflammatory mediators resulting in intestinal injury and inflammation. The most prevalent animal model to study TcdA/TcdB-induced intestinal injury involves injecting toxin into the lumen of a surgically generated "ileal loop." This model is time-consuming and exhibits variability depending on the expertise of the surgeon. Furthermore, the target organ of C. difficile infection (CDI) in humans is the colon, not the ileum. In the current study, we describe a new model of CDI that involves intrarectal instillation of TcdA/TcdB into the mouse colon. The administration of TcdA/TcdB triggered colonic inflammation and neutrophil and macrophage infiltration as well as increased epithelial barrier permeability and intestinal epithelial cell death. The damage and inflammation triggered by TcdA/TcdB isolates from the VPI and 630 strains correlated with the concentration of TcdA and TcdB produced. TcdA/TcdB exposure increased the expression of a number of inflammatory mediators associated with human CDI, including interleukin-6 (IL-6), gamma interferon (IFN-γ), and IL-1β. Finally, we were able to demonstrate that TcdA was much more potent at inducing colonic injury than was TcdB but TcdB could act synergistically with TcdA to exacerbate injury. Taken together, our data indicate that the intrarectal murine model provides a robust and efficient system to examine the effects of TcdA/TcdB on the induction of inflammation and colonic tissue damage in the context of human CDI.
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20
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Abstract
The gastrointestinal system is a common entry point for pathogenic microbes to access the inner environment of the body. Anti-microbial factors produced by the intestinal mucosa limit the translocation of both commensal and pathogenic microbes across the intestinal epithelial cell barrier. The regulation of these host defense mechanisms largely depends on the activation of innate immune receptors by microbial molecules. Under steady-state conditions, the microbiota provides constitutive signals to the innate immune system, which helps to maintain a healthy inflammatory tone within the intestinal mucosa and, thus, enhances resistance to infection with enteric pathogens. During an acute infection, the intestinal epithelial cell barrier is breached, and the detection of microbial molecules in the intestinal lamina propria rapidly stimulates innate immune signaling pathways that coordinate early defense mechanisms. Herein, we review how microbial molecules shed by both commensal and pathogenic microbes direct host defenses at the intestinal mucosa. We highlight the signaling pathways, effector molecules, and cell populations that are activated by microbial molecule recognition and, thereby, are involved in the maintenance of homeostatic levels of host defense and in the early response to acute enteric infection. Finally, we discuss how manipulation of these host defense pathways by stimulating innate immune receptors is a potential therapeutic strategy to prevent or alleviate intestinal disease.
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Affiliation(s)
- Melissa A Kinnebrew
- Infectious Diseases Service, Department of Medicine, Immunology Program, Memorial Sloan-Kettering Cancer Center, New York, NY, USA
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21
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Liu X, Wang JM. Iridoid glycosides fraction of Folium syringae leaves modulates NF-κB signal pathway and intestinal epithelial cells apoptosis in experimental colitis. PLoS One 2011; 6:e24740. [PMID: 21931839 PMCID: PMC3172289 DOI: 10.1371/journal.pone.0024740] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2011] [Accepted: 08/16/2011] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND AND AIMS Iridoid glycosides (IG), the major active fraction of F. syringae leaves has been demonstrated to have strong anti-inflammatory properties to ulcerative colitis (UC) in our previous study. The aim of this study was to investigate whether IG modulates the inflammatory response in experimental colitis at the level of NF-κB signal pathway and epithelial cell apoptosis. METHODS UC in rats was induced by administration with dextran sulfate sodium (DSS) in drinking water. The inflammatory damage was assessed by disease activity index (DAI), macroscopic findings, histology and myeloperoxidase (MPO) activity. The effect of IG on pro-inflammatory cytokines TNF-α, IL-8, COX-2 and regulatory peptide TGF-β1 was measured. Epithelial cell apoptosis and the protein and mRNA expressions of Fas/FasL, Bcl-2/Bax, caspase-3, NF-κB p65, IκBα, p-IκBα and IKKβ were detected by TUNEL method, immunohistochemistry, Western blotting and real-time quantitative PCR, respectively. RESULTS IG significantly ameliorated macroscopic damage and histological changes, reduced the activity of MPO, and strongly inhibited epithelial cell apoptosis. Moreover, IG markedly depressed TNF-α, IL-8, COX-2 and TGF-β1 levels in the colon tissues in a dose-dependent manner. Furthermore, IG significantly blocked of NF-κB signaling by inhibiting IκBα phosphorylation/degradation and IKKβ activity, down-regulated the protein and mRNA expressions of Fas/FasL, Bax and caspase-3, and activated Bcl-2 in intestinal epithelial cells. CONCLUSIONS These results demonstrated for the first time that IG possessed marked protective effects on experimental colitis through inhibition of epithelial cell apoptosis and blockade of NF-κB signal pathway.
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Affiliation(s)
- Xin Liu
- College of Pharmaceutical Sciences, Zhejiang University, Hangzhou, China.
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22
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Koch S, Nusrat A. The life and death of epithelia during inflammation: lessons learned from the gut. ANNUAL REVIEW OF PATHOLOGY 2011; 7:35-60. [PMID: 21838548 DOI: 10.1146/annurev-pathol-011811-120905] [Citation(s) in RCA: 101] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Epithelial cells form protective barriers that physically separate an organism from the outside world. Rather than being merely static, impregnable shields, epithelia are highly dynamic structures that can adjust their proliferation, differentiation, and death in response to intrinsic and extrinsic signals. The advantages as well as pitfalls of this flexibility are highlighted in inflammatory disorders such as inflammatory bowel diseases and psoriasis, which are characterized by a chronically dysregulated homeostasis of the epithelium. In recent years, it has become increasingly apparent that epithelial cells communicate with their surroundings through converging, integrated signaling cascades and that even minor alterations in these pathways can have dramatic pathologic consequences. In this review, we discuss how inflammatory cytokines and other signaling molecules, directly or through cross talk, regulate epithelial homeostasis in the intestine, and we highlight parallels and differences in a few other organs.
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Affiliation(s)
- Stefan Koch
- Epithelial Pathobiology Unit, Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, Georgia 30322, USA.
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Guma M, Stepniak D, Shaked H, Spehlmann ME, Shenouda S, Cheroutre H, Vicente-Suarez I, Eckmann L, Kagnoff MF, Karin M. Constitutive intestinal NF-κB does not trigger destructive inflammation unless accompanied by MAPK activation. ACTA ACUST UNITED AC 2011; 208:1889-900. [PMID: 21825016 PMCID: PMC3171091 DOI: 10.1084/jem.20110242] [Citation(s) in RCA: 131] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Constitutive NF-κB activation in IECs induces inflammatory cytokines and chemokines in the lamina propria, but does not result in overt tissue damage unless acute inflammatory insults are present, causing TNF-dependent destruction and barrier disruption. Nuclear factor (NF)-κB, activated by IκB kinase (IKK), is a key regulator of inflammation, innate immunity, and tissue integrity. NF-κB and one of its main activators and transcriptional targets, tumor necrosis factor (TNF), are up-regulated in many inflammatory diseases that are accompanied by tissue destruction. The etiology of many inflammatory diseases is poorly understood, but often depends on genetic factors and environmental triggers that affect NF-κB and related pathways. It is unknown, however, whether persistent NF-κB activation is sufficient for driving symptomatic chronic inflammation and tissue damage. To address this question, we generated IKKβ(EE)IEC mice, which express a constitutively active form of IKKβ in intestinal epithelial cell (IECs). IKKβ(EE)IEC mice exhibit NF-κB activation in IECs and express copious amounts of inflammatory chemokines, but only small amounts of TNF. Although IKKβ(EE)IEC mice exhibit inflammatory cell infiltration in the lamina propria (LP) of their small intestine, they do not manifest tissue damage. Yet, upon challenge with relatively mild immune and microbial stimuli, IKKβ(EE)IEC mice succumb to destructive acute inflammation accompanied by enterocyte apoptosis, intestinal barrier disruption, and bacterial translocation. Inflammation is driven by massive TNF production, which requires additional activation of p38 and extracellular-signal–regulated kinase mitogen-activated protein kinases (MAPKs).
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Affiliation(s)
- Monica Guma
- Laboratory of Gene Regulation and Signal Transduction, Department of Pharmacology, School of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
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Abstract
Clostridium difficile is the most common cause of nosocomial bacterial diarrhoea in the Western world. Diarrhoea and colitis are caused by the actions of toxins A and B released by pathogenic strains of C. difficile. Adaptive immune responses to these toxins influence the outcomes of C. difficile infection (CDI). Symptomless carriers of toxinogenic C. difficile and those with a single episode of CDI without recurrence show more robust antitoxin immune responses than those with symptomatic and recurrent disease. Immune-based approaches to CDI therapy and prevention have been developed using active vaccination or passive immunotherapy targeting C. difficile toxins. Innate immune responses to C. difficile and its toxins are also central to the pathophysiology of CDI. An acute intestinal inflammatory response with prominent neutrophil infiltration and associated tissue injury is characteristic of CDI. Furthermore, inhibiting this acute inflammatory response can protect against the intestinal injury that results from exposure to C. difficile toxins in animal models. Studies examining host risk factors for CDI have led to validated clinical prediction tools for risk of primary and of recurrent disease. Risk factors associated with severe CDI with poor clinical outcomes have also been identified and include marked elevation of the peripheral white blood cell count and elevated creatinine. However, further work is needed in this area to guide the clinical application of new approaches to disease prevention and treatment including new antimicrobials as well as passive and active immunization.
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Affiliation(s)
- Ciarán P Kelly
- Gastroenterology Division, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, USA
| | - Lorraine Kyne
- Department of Medicine for the Older Person, Mater Misericordiae University Hospital and University College, Dublin, Ireland
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25
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Broquet AH, Hirata Y, McAllister CS, Kagnoff MF. RIG-I/MDA5/MAVS are required to signal a protective IFN response in rotavirus-infected intestinal epithelium. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2011; 186:1618-26. [PMID: 21187438 DOI: 10.4049/jimmunol.1002862] [Citation(s) in RCA: 170] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Rotavirus is a dsRNA virus that infects epithelial cells that line the surface of the small intestine. It causes severe diarrheal illness in children and ∼500,000 deaths per year worldwide. We studied the mechanisms by which intestinal epithelial cells (IECs) sense rotavirus infection and signal IFN-β production, and investigated the importance of IFN-β production by IECs for controlling rotavirus production by intestinal epithelium and virus excretion in the feces. In contrast with most RNA viruses, which interact with either retinoic acid-inducible gene I (RIG-I) or melanoma differentiation-associated gene 5 (MDA5) inside cells, rotavirus was sensed by both RIG-I and MDA5, alone and in combination. Rotavirus did not signal IFN-β through either of the dsRNA sensors TLR3 or dsRNA-activated protein kinase (PKR). Silencing RIG-I or MDA5, or their common adaptor protein mitochondrial antiviral signaling protein (MAVS), significantly decreased IFN-β production and increased rotavirus titers in infected IECs. Overexpression of laboratory of genetics and physiology 2, a RIG-I-like receptor that interacts with viral RNA but lacks the caspase activation and recruitment domains required for signaling through MAVS, significantly decreased IFN-β production and increased rotavirus titers in infected IECs. Rotavirus-infected mice lacking MAVS, but not those lacking TLR3, TRIF, or PKR, produced significantly less IFN-β and increased amounts of virus in the intestinal epithelium, and shed increased quantities of virus in the feces. We conclude that RIG-I or MDA5 signaling through MAVS is required for the activation of IFN-β production by rotavirus-infected IECs and has a functionally important role in determining the magnitude of rotavirus replication in the intestinal epithelium.
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MESH Headings
- Adaptor Proteins, Signal Transducing/deficiency
- Adaptor Proteins, Signal Transducing/physiology
- Animals
- Cell Line
- Chlorocebus aethiops
- DEAD Box Protein 58
- DEAD-box RNA Helicases/deficiency
- DEAD-box RNA Helicases/physiology
- HT29 Cells
- Humans
- Interferon-Induced Helicase, IFIH1
- Interferon-beta/biosynthesis
- Interferon-beta/physiology
- Intestinal Mucosa/enzymology
- Intestinal Mucosa/immunology
- Intestinal Mucosa/virology
- Membrane Proteins/deficiency
- Membrane Proteins/physiology
- Mice
- Mice, 129 Strain
- Mice, Inbred C57BL
- Mice, Knockout
- Nerve Tissue Proteins/deficiency
- Nerve Tissue Proteins/physiology
- RNA Helicases/genetics
- RNA Helicases/physiology
- RNA, Viral/biosynthesis
- RNA, Viral/genetics
- Receptors, Cell Surface
- Receptors, Immunologic
- Response Elements/immunology
- Rotavirus/genetics
- Rotavirus/immunology
- Signal Transduction/genetics
- Signal Transduction/immunology
- Virus Replication/genetics
- Virus Replication/immunology
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Affiliation(s)
- Alexis H Broquet
- Laboratory of Mucosal Immunology, Department of Medicine, University of California, San Diego, La Jolla, CA 92093, USA
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Chen L, Meng Q, Kao W, Xia Y. IκB kinase β regulates epithelium migration during corneal wound healing. PLoS One 2011; 6:e16132. [PMID: 21264230 PMCID: PMC3022035 DOI: 10.1371/journal.pone.0016132] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Accepted: 12/07/2010] [Indexed: 01/04/2023] Open
Abstract
The IKKβ is known to regulate transcription factor NF-κB activation leading to inflammatory responses. Recent gene knockout studies have shown that IKKβ can orchestrate local inflammatory responses and regulate homeostasis of epithelial tissues. To investigate whether IKKβ has an intrinsic role in epithelial cells, we established an in vivo system in the immune privileged corneal epithelium. We generated triple transgenic Krt12rtTA/rtTAt/tet-O-Cre/IkkβF/F (IkkβΔCE/ΔCE) mice by crossing the Krt12-rtTA knock-in mice, which express the reverse tetracycline transcription activator in corneal epithelial cells, with the tet-O-Cre and IkkβF/F mice. Doxcycline-induced IKKβ ablation occurred in corneal epithelial cells of triple transgenic IkkβΔCE/ΔCE mice, but loss of IKKβ did not cause ocular abnormalities in fetal development and postnatal maintenance. Instead, loss of IKKβ significantly delayed healing of corneal epithelial debridement without affecting cell proliferation, apoptosis or macrophage infiltration. In vitro studies with human corneal epithelial cells (HCEpi) also showed that IKKβ was required for cytokine-induced cell migration and wound closure but was dispensable for cell proliferation. In both in vivo and in vitro settings, IKKβ was required for optimal activation of NF-κB and p38 signaling in corneal epithelial cells, and p38 activation is likely mediated through formation of an IKKβ-p38 protein complex. Thus, our studies in corneal epithelium reveal a previously un-recognized role for IKKβ in the control of epithelial cell motility and wound healing.
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Affiliation(s)
- Liang Chen
- Department of Environmental Health, University of Cincinnati Medical Center, Cincinnati, Ohio, United States of America
| | - Qinghang Meng
- Department of Environmental Health, University of Cincinnati Medical Center, Cincinnati, Ohio, United States of America
| | - Winston Kao
- Department of Ophthalmology, University of Cincinnati Medical Center, Cincinnati, Ohio, United States of America
| | - Ying Xia
- Department of Environmental Health, University of Cincinnati Medical Center, Cincinnati, Ohio, United States of America
- * E-mail:
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Thomas JA, Newman KC, Doshi S, Logan N, Musher DM. Bacteraemia from an unrecognized source (occult bacteraemia) occurring during Clostridium difficile infection. ACTA ACUST UNITED AC 2011; 43:269-74. [PMID: 21231808 DOI: 10.3109/00365548.2010.546366] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
BACKGROUND The purpose of this investigation was to determine if disruption of the colonic epithelium during Clostridium difficile infection (CDI) is associated with bacteraemia due to secondary bacterial invasion by enteric organisms. METHODS We reviewed the medical records of 505 randomly selected individuals from a database of patients who tested positive for C. difficile toxin and identified bacteraemias that occurred in 2 periods-the pre-CDI and post-CDI periods. Medical records were reviewed to determine a source for each case of bacteraemia. Staphylococcal bacteraemias were excluded from the analysis. RESULTS In the pre-CDI period, 28 of 505 (5.5%) patients had non-staphylococcal bacteraemia. A focus of infection was found in 24 of 28 (85.7%) cases. During CDI, 30 of 505 (5.9%) patients had non-staphylococcal bacteraemia; in the majority (19 cases, 63.3%) a focus of infection was not identified (p < 0.001). In the pre-CDI period, 16 of 28 (57.1%) blood cultures yielded Gram-negative pathogens compared to 9 of 30 (30%) in the CDI period (p = 0.04). Seven of 28 (25%) blood cultures in the pre-CDI period yielded enterococci compared to 15 of 30 (50%) in the CDI period (p = 0.05). CONCLUSIONS The incidence of non-staphylococcal bacteraemias in the pre- and post-CDI periods was nearly the same. Cases of bacteraemias in the CDI period more frequently involved organisms of unknown source and uncertain pathogenicity, and were usually not found to require antimicrobial therapy. The data favour the assumption that CDI-associated bacteraemia may be associated with bacterial invasion of the damaged colonic epithelium.
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Affiliation(s)
- Jimmy A Thomas
- Medical Care Line (Infectious Disease Section), Michael E. DeBakey Veterans Affairs Medical Center, Houston, Texas, USA
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Sun X, Savidge T, Feng H. The enterotoxicity of Clostridium difficile toxins. Toxins (Basel) 2010; 2:1848-80. [PMID: 22069662 PMCID: PMC3153265 DOI: 10.3390/toxins2071848] [Citation(s) in RCA: 74] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Revised: 06/23/2010] [Accepted: 07/09/2010] [Indexed: 02/06/2023] Open
Abstract
The major virulence factors of Clostridium difficile infection (CDI) are two large exotoxins A (TcdA) and B (TcdB). However, our understanding of the specific roles of these toxins in CDI is still evolving. It is now accepted that both toxins are enterotoxic and proinflammatory in the human intestine. Both purified TcdA and TcdB are capable of inducing the pathophysiology of CDI, although most studies have focused on TcdA. C. difficile toxins exert a wide array of biological activities by acting directly on intestinal epithelial cells. Alternatively, the toxins may target immune cells and neurons once the intestinal epithelial barrier is disrupted. The toxins may also act indirectly by stimulating cells to produce chemokines, proinflammatory cytokines, neuropeptides and other neuroimmune signals. This review considers the mechanisms of TcdA- and TcdB-induced enterotoxicity, and recent developments in this field.
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Affiliation(s)
- Xingmin Sun
- Tufts Cummings School of Veterinary Medicine, North Grafton, MA, 01536, USA;
| | - Tor Savidge
- The University of Texas Medical Branch, Galveston, TX, 77555, USA;
| | - Hanping Feng
- Tufts Cummings School of Veterinary Medicine, North Grafton, MA, 01536, USA;
- Author to whom correspondence should be addressed; ; Tel.: +1-508-887-4252; Fax: +1-508-839-7911
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GM-CSF-facilitated dendritic cell recruitment and survival govern the intestinal mucosal response to a mouse enteric bacterial pathogen. Cell Host Microbe 2010; 7:151-63. [PMID: 20159620 DOI: 10.1016/j.chom.2010.01.006] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2009] [Revised: 12/17/2009] [Accepted: 01/19/2010] [Indexed: 11/22/2022]
Abstract
Granulocyte-macrophage colony-stimulating factor (GM-CSF) promotes dendritic cell (DC) differentiation and survival in vitro. However, its role in host defense at the intestinal mucosa is unknown. We report that infection with the mouse enteric pathogen, Citrobacter rodentium, increased colonic GM-CSF production and CD11c(+) DC recruitment. After infection, GM-CSF(-/-) mice had fewer mucosal CD11c(+) DCs, greater bacterial burden, increased mucosal inflammation and systemic spread of infection, decreased antibody responses, and delayed pathogen clearance. This defective mucosal response was rescued by GM-CSF administration to GM-CSF(-/-) mice and mimicked by CD11c(+) DC depletion in wild-type animals. Diminished mucosal DC numbers in infected GM-CSF(-/-) mice reflected decreased DC recruitment and survival, with the recruitment defect being related to a failure to upregulate epithelial cell production of the DC chemoattractant, CCL22. Thus, GM-CSF produced in the intestinal mucosa acts to enhance host protection against an enteric bacterial pathogen through regulating recruitment and survival of DCs.
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Viswanathan VK, Mallozzi MJ, Vedantam G. Clostridium difficile infection: An overview of the disease and its pathogenesis, epidemiology and interventions. Gut Microbes 2010; 1:234-242. [PMID: 21327030 PMCID: PMC3023605 DOI: 10.4161/gmic.1.4.12706] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2009] [Revised: 06/15/2010] [Accepted: 06/16/2010] [Indexed: 02/03/2023] Open
Abstract
Clostridium difficile infection (CDI) is the primary cause of antibiotic-associated diarrhea and is a significant nosocomial disease. In the past ten years, variant toxin-producing strains of C. difficile have emerged, that have been associated with severe disease as well as outbreaks worldwide. This review summarizes current information on C. difficile pathogenesis and disease, and highlights interventions used to combat single and recurrent episodes of CDI.
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Affiliation(s)
- VK Viswanathan
- Department of Veterinary Science and Microbiology; University of Arizona; Tucson, AZ USA
| | - MJ Mallozzi
- Department of Veterinary Science and Microbiology; University of Arizona; Tucson, AZ USA
| | - Gayatri Vedantam
- Department of Veterinary Science and Microbiology; University of Arizona; Tucson, AZ USA,Research Service; Southern Arizona VA Healthcare System; Tucson, AZ USA
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Antiapoptotic proteins Bcl-2 and Bcl-XL inhibit Clostridium difficile toxin A-induced cell death in human epithelial cells. Infect Immun 2009; 77:5400-10. [PMID: 19797069 DOI: 10.1128/iai.00485-09] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
It has been well established that Clostridium difficile toxin A (TcdA) induces cell death in human epithelial cells. However, the mechanism of TcdA-induced cell death remains to be fully characterized. Here, we show that TcdA induces dose-dependent cell death in ovarian carcinoma and colonic carcinoma cell lines. TcdA-mediated cell death, as well as caspase 8 and caspase 3 activation, were specifically abrogated by anti-toxin antibodies. Although caspase 8 and caspase 3 were activated by TcdA in OVCAR3 ovarian carcinoma and T84 colonic cancer cells, pancaspase and caspase 8, 3, and 9 inhibitors did not block TcdA-induced cell death. In contrast, tumor necrosis factor-related apoptosis-inducing ligand-induced cell death was nearly completely blocked by caspase inhibitors in OVCAR3 cells. In these cells, TcdA induces the mitochondrial pathway of apoptosis, as demonstrated by changes in mitochondrial outer membrane permeabilization (MOMP). Furthermore, overexpression of the antiapoptotic proteins Bcl-2 and Bcl-X(L) significantly inhibited TcdA-induced cell death, as well as TcdA-induced MOMP. Conversely, small interfering RNA-mediated inhibition of Bcl-X(L) in TcdA-resistant SKOV3ip1 cells enhanced TcdA-induced cell death. Overexpression of the antiapoptotic proteins Bcl-2 and Bcl-X(L) in T84 cells also inhibited TcdA-induced cell death. Altogether, our data demonstrate that TcdA induces cell death in both ovarian and colonic cancer cells preferentially via the mitochondrial pathway of apoptosis by a death receptor-independent and a caspase-independent mechanism. This process is regulated by antiapoptotic members of the Bcl-2 family.
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Lee JY, Kim H, Cha MY, Park HG, Kim YJ, Kim IY, Kim JM. Clostridium difficile toxin A promotes dendritic cell maturation and chemokine CXCL2 expression through p38, IKK, and the NF-kappaB signaling pathway. J Mol Med (Berl) 2008; 87:169-80. [PMID: 18985311 DOI: 10.1007/s00109-008-0415-2] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2008] [Revised: 10/13/2008] [Accepted: 10/20/2008] [Indexed: 12/22/2022]
Abstract
Clostridium difficile toxin A causes acute colitis associated with intense infiltrating neutrophils. Although dendritic cells (DCs) play an important role in the regulation of inflammation, little is known about the effects of toxin A on the maturation and neutrophil-attracting chemokine expression in DCs. This study investigated whether C. difficile toxin A could influence the maturation of mouse bone-marrow-derived DCs and chemokine CXCL2 expression. Toxin A increased the DC maturation which was closely related to CXCL2 upregulation. Concurrently, toxin A activated the signals of p65/p50 nuclear factor kappa B (NF-kappaB) heterodimers and phospho-I kappa B kinase (IKK) in DCs. The increased DC maturation, CXCL2 expression, and neutrophil chemoattraction were significantly downregulated in the NF-kappaB knockout mice. In addition, toxin A activated the phosphorylated signals of mitogen-activated protein kinases (MAPKs), such as ERK, p38, and JNK. Of all three MAPK signals, p38 MAPK was significantly related to DC maturation. Thus, suppression of p38 activity using SB203580 and siRNA transfection resulted in the significant reduction of IKK activity, DC maturation, and CXCL2 upregulation by toxin A. These results suggest that p38 MAPK may lead to the activation of IKK and NF-kappaB signaling, resulting in enhanced DC maturation and CXCL2 expression in response to C. difficile toxin A stimulation.
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Affiliation(s)
- Jin Young Lee
- Department of Microbiology, Hanyang University College of Medicine, 17 Haengdang-dong, Sungdong-gu, Seoul, 133-791, South Korea
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Hord NG. Eukaryotic-microbiota crosstalk: potential mechanisms for health benefits of prebiotics and probiotics. Annu Rev Nutr 2008; 28:215-31. [PMID: 18489258 DOI: 10.1146/annurev.nutr.28.061807.155402] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The ability to link dietary consumption of prebiotic food ingredients and probiotic microorganisms to health benefits rests, in part, on our ability to identify both the extent to which these factors alter human microbiome activity and/or structure and the ability to engage eukaryotic cells necessary to transduce signals originating from the microbiome. The human microbiome consists of bacterial, archaeal, and fungal components that reside in mucosal surfaces of the gut, the airways, and the urogenital tract. Characterization of the symbiotic nature of the relationship between eukaryotic cells and the bacterial and archaeal components of the microbiota has revealed significant contributions in energy balance, bowel function, immunologic function, sensory perception, glycemic control, and blood pressure regulation. Elucidating the complex interactions between the microbiota and their associated epithelial, immune, and neural cells may provide mechanistic insights and a rational basis for our belief that dietary consumption of probiotic microorganisms and prebiotics produces health benefits.
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Affiliation(s)
- Norman G Hord
- Department of Food Science and Human Nutrition, Michigan State University, East Lansing, Michigan 48824, USA.
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Inhibition of apoptosis in Bacteroides fragilis enterotoxin-stimulated intestinal epithelial cells through the induction of c-IAP-2. Eur J Immunol 2008; 38:2190-9. [PMID: 18624297 DOI: 10.1002/eji.200838191] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Enterotoxigenic Bacteroides fragilis produces an approximately 20-kDa heat-labile enterotoxin (BFT) that plays an essential role in generating mucosal inflammation. Although it is well known that proinflammatory signals are expressed in BFT-stimulated intestinal epithelial cells, cell death processes have not been elucidated. BFT induced apoptosis in HT-29 cells, but the apoptosis was first apparent 36 h after stimulation. During the early period of BFT stimulation, expression of cellular inhibitor of apoptosis protein-2 (c-IAP2) increased, and inhibition of c-IAP2 augmented the apoptotic cell death. Inhibition of BFT-induced COX-2 expression decreased prostaglandin E(2) (PGE(2)) production, which led not only to a decrease of c-IAP2 activity but also to an enhancement of DNA fragmentation in the early period of BFT stimulation. Furthermore, apoptosis inhibition through PGE(2) and c-IAP2 was mainly regulated by a p38 mitogen-activated protein kinase (MAPK). These results suggest that the inhibition of apoptosis may be mediated by a sequential pathway, including MAPK, COX-2, PGE(2) and c-IAP2, in the early period of stimulation. The delay in the onset of epithelial cell apoptosis after enterotoxigenic B. fragilis infection may be important to the host since it can provides sufficient time for epithelial cells to generate signals for the activation of mucosal inflammation and it may increase the chances of bacterial colonization.
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Bobak DA. The molecular pathogenesis of Clostridium difficile-associated disease. Curr Infect Dis Rep 2008; 10:111-5. [DOI: 10.1007/s11908-008-0020-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Kim H, Rhee SH, Pothoulakis C, Lamont JT. Inflammation and apoptosis in Clostridium difficile enteritis is mediated by PGE2 up-regulation of Fas ligand. Gastroenterology 2007; 133:875-86. [PMID: 17854595 DOI: 10.1053/j.gastro.2007.06.063] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2006] [Accepted: 05/31/2007] [Indexed: 02/05/2023]
Abstract
BACKGROUND & AIMS Clostridium difficile toxin A causes acute inflammation and fluid secretion in experimental animals and patients with C difficile infection. We previously reported that toxin A increased cyclooxygenase-2/prostaglandin E(2) (PGE(2)) expression and apoptosis in human colonocytes. Here, we assessed the role of secreted PGE(2) in inflammation and enterocyte apoptosis in toxin A enteritis. METHODS Effects of PGE(2) and PGE(2) blockade on toxin A-induced apoptosis of human colonocytes (NCM460) and of PGE(2) or toxin A on the Fas ligand (FasL) induction were analyzed by flow cytometry and Western blot. Functional activity of elevated FasL on colonocytes was assessed by coculture of colonocytes with Fas bearing Jurkat T cells. The involvement of PGE(2)-dependent Fas/FasL activation in toxin A enteritis was further assessed in either scid or FasL and Fas deficient mice. RESULTS Inhibition of cyclooxygenase-2 by NS-398 and of PGE(2) using a blocking antibody markedly attenuated apoptosis in colonocytes exposed to toxin A. Enhanced expression and release of FasL followed PGE(2) or toxin A exposure in vivo and in vitro and also was significantly attenuated by treatment with NS-398 and PGE(2) blocking antibody. PGE(2) acting through an EP1 receptor activated nuclear factor-kappaB, which induced transcription of FasL. Toxin A enteritis was accompanied by increased cellular infiltration, fluid secretion, and mucosal damage in control mice, but this response was markedly reduced in both Fas(-/-) and FasL(-/-) mice. CONCLUSIONS Toxin A enteritis involves release of PGE(2), which activates the Fas/FasL system, causing enterocyte apoptosis and inflammation.
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Affiliation(s)
- Ho Kim
- Division of Gastroenterology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA
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Lee JY, Park HR, Oh YK, Kim YJ, Youn J, Han JS, Kim JM. Effects of transcription factor activator protein-1 on interleukin-8 expression and enteritis in response to Clostridium difficile toxin A. J Mol Med (Berl) 2007; 85:1393-404. [PMID: 17639289 DOI: 10.1007/s00109-007-0237-7] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2007] [Revised: 06/01/2007] [Accepted: 06/12/2007] [Indexed: 02/07/2023]
Abstract
Clostridium difficile toxin A causes acute colitis associated with intense infiltration of neutrophils. Although C. difficile toxin A is known to induce nuclear factor-kappaB-mediated chemokine expression in intestinal epithelial cells, little is known about its effect on the regulation of activator protein-1 (AP-1) by mitogen-activated protein kinase (MAPK). In the present study, we investigated whether the MAPK and AP-1 signaling pathway is involved in interleukin (IL)-8 expression and enteric inflammation in response to stimulation with toxin A. Toxin A activated MAPK and AP-1 composed of c-Jun/c-Fos heterodimers in primary intestinal epithelial cells and HT-29 cell lines. Transfection with mutant genes for Ras, c-Jun, p38, or c-Jun N-terminal kinase (JNK) significantly inhibited C. difficile toxin A-induced activation of AP-1 and expression of IL-8 in HT-29 cell lines. Furthermore, the p38 inhibitor SB203580 attenuated toxin A-induced inflammation in vivo in the mouse ileum, evidenced by a significant decrease in neutrophil infiltration, villous destruction, and mucosal congestion. Our results suggest that the Ras/MAPK cascade acts as the upstream signaling for AP-1 activation and IL-8 expression in toxin A-stimulated intestinal epithelial cells and may be involved in the development of enteritis after infection with toxin A-producing C. difficile.
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Affiliation(s)
- Jin Young Lee
- Department of Microbiology and Institute of Biomedical Science, Hanyang University College of Medicine, Seoul, 133-791, South Korea
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