1
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Zundler S, Schulze LL, Neurath MF. Controlling in and out - the future of interfering with immune cell trafficking in inflammatory bowel disease. Expert Rev Clin Immunol 2023; 19:155-167. [PMID: 36427088 DOI: 10.1080/1744666x.2023.2152794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
INTRODUCTION Immune cell trafficking is a key requirement in the pathogenesis of inflammatory bowel diseases. Consistently, therapeutic strategies to target immune cell trafficking have been established and continue to be developed for the treatment of ulcerative colitis and Crohn's disease. AREAS COVERED In this review, we briefly summarize the most important checkpoints of intestinal immune cell trafficking and their importance during IBD. Moreover, we provide an overview of associated therapeutic targets and previous as well as current efforts on treatment strategies related to these targets. EXPERT OPINION Finally, we comment on potential future developments that might shape the field of immune cell trafficking in the context of IBD.
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Affiliation(s)
- Sebastian Zundler
- Department of Medicine 1 and Deutsches Zentrum Immuntherapie, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Lisa Lou Schulze
- Department of Medicine 1 and Deutsches Zentrum Immuntherapie, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Markus F Neurath
- Department of Medicine 1 and Deutsches Zentrum Immuntherapie, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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2
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Sphingosine 1-phosphate modulation and immune cell trafficking in inflammatory bowel disease. Nat Rev Gastroenterol Hepatol 2022; 19:351-366. [PMID: 35165437 DOI: 10.1038/s41575-021-00574-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 12/22/2021] [Indexed: 12/12/2022]
Abstract
Immune cell trafficking is a critical element of the intestinal immune response, both in homeostasis and in pathological conditions associated with inflammatory bowel disease (IBD). This process involves adhesion molecules, chemoattractants and receptors expressed on immune cell surfaces, blood vessels and stromal intestinal tissue as well as signalling pathways, including those modulated by sphingosine 1-phosphate (S1P). The complex biological processes of leukocyte recruitment, activation, adhesion and migration have been targeted by various monoclonal antibodies (vedolizumab, etrolizumab, ontamalimab). Promising preclinical and clinical data with several oral S1P modulators suggest that inhibition of lymphocyte egress from the lymph nodes to the bloodstream might be a safe and efficacious alternative mechanism for reducing inflammation in immune-mediated disorders, including Crohn's disease and ulcerative colitis. Although various questions remain, including the potential positioning of S1P modulators in treatment algorithms and their long-term safety, this novel class of compounds holds great promise. This Review summarizes the critical mediators and mechanisms involved in immune cell trafficking in IBD and the available evidence for efficacy, safety and pharmacokinetics of S1P receptor modulators in IBD and other immune-mediated disorders. Further, it discusses potential future approaches to incorporate S1P modulators into the treatment of IBD.
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3
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Ren B, Xia H, Liao Y, Zhou H, Wang Z, Shi Y, Zhu M. Endothelial SIRPα signaling controls VE-cadherin endocytosis for thymic homing of progenitor cells. eLife 2022; 11:69219. [PMID: 35511221 PMCID: PMC9071265 DOI: 10.7554/elife.69219] [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: 04/08/2021] [Accepted: 04/19/2022] [Indexed: 11/13/2022] Open
Abstract
Thymic homing of hematopoietic progenitor cells (HPCs) is tightly regulated for proper T cell development. Previously we have identified a subset of specialized thymic portal endothelial cells (TPECs), which is important for thymic HPC homing. However, the underlying molecular mechanism still remains unknown. Here, we found that signal regulatory protein alpha (SIRPα) is preferentially expressed on TPECs. Disruption of CD47-SIRPα signaling in mice resulted in reduced number of thymic early T cell progenitors (ETPs), impaired thymic HPC homing, and altered early development of thymocytes. Mechanistically, Sirpa-deficient ECs and Cd47-deficient bone marrow progenitor cells or T lymphocytes demonstrated impaired transendothelial migration (TEM). Specifically, SIRPα intracellular ITIM motif-initiated downstream signaling in ECs was found to be required for TEM in an SHP2- and Src-dependent manner. Furthermore, CD47 signaling from migrating cells and SIRPα intracellular signaling were found to be required for VE-cadherin endocytosis in ECs. Thus, our study reveals a novel role of endothelial SIRPα signaling for thymic HPC homing for T cell development.
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Affiliation(s)
- Boyang Ren
- The Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of the Chinese Academy of Sciences, Beijing, China
| | - Huan Xia
- The Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of the Chinese Academy of Sciences, Beijing, China
| | - Yijun Liao
- The Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of the Chinese Academy of Sciences, Beijing, China
| | - Hang Zhou
- The Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of the Chinese Academy of Sciences, Beijing, China
| | - Zhongnan Wang
- The Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Yaoyao Shi
- The Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China
| | - Mingzhao Zhu
- The Key Laboratory of Infection and Immunity, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China.,College of Life Sciences, University of the Chinese Academy of Sciences, Beijing, China
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4
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Lagarrigue F, Tan B, Du Q, Fan Z, Lopez-Ramirez MA, Gingras AR, Wang H, Qi W, Sun H. Direct Binding of Rap1 to Talin1 and to MRL Proteins Promotes Integrin Activation in CD4 + T Cells. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2022; 208:1378-1388. [PMID: 35197328 PMCID: PMC9644409 DOI: 10.4049/jimmunol.2100843] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 12/27/2021] [Indexed: 12/26/2022]
Abstract
Agonist-induced Rap1 GTP loading results in integrin activation involved in T cell trafficking and functions. MRL proteins Rap1-interacting adapter molecule (RIAM) and lamellipodin (LPD) are Rap1 effectors that can recruit talin1 to integrins, resulting in integrin activation. Recent work also implicates direct Rap1-talin1 interaction in integrin activation. Here, we analyze in mice the connections between Rap1 and talin1 that support integrin activation in conventional CD4+ T (Tconv) and CD25HiFoxp3+CD4+ regulatory T (Treg) cells. Talin1(R35E, R118E) mutation that disrupts both Rap1 binding sites results in a partial defect in αLβ2, α4β1, and α4β7 integrin activation in both Tconv and Treg cells with resulting defects in T cell homing. Talin1(R35E,R118E) Tconv manifested reduced capacity to induce colitis in an adoptive transfer mouse model. Loss of RIAM exacerbates the defects in Treg cell function caused by the talin1(R35E,R118E) mutation, and deleting both MRL proteins in combination with talin1(R35E,R118E) phenocopy the complete lack of integrin activation observed in Rap1a/b-null Treg cells. In sum, these data reveal the functionally significant connections between Rap1 and talin1 that enable αLβ2, α4β1, and α4β7 integrin activation in CD4+ T cells.
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Affiliation(s)
- Frederic Lagarrigue
- Institut de Pharmacologie et Biologie Structurale, Université de Toulouse, CNRS, Université Paul Sabatier, Toulouse, France
| | - Boyang Tan
- Department of Medicine, University of California, San Diego, La Jolla, CA; and
| | - Qinyi Du
- Department of Medicine, University of California, San Diego, La Jolla, CA; and
| | - Zhichao Fan
- Department of Immunology, School of Medicine, University of Connecticut, UConn Health, Farmington, CT
| | | | - Alexandre R Gingras
- Department of Medicine, University of California, San Diego, La Jolla, CA; and
| | - Hsin Wang
- Department of Medicine, University of California, San Diego, La Jolla, CA; and
| | - Weiwei Qi
- Department of Medicine, University of California, San Diego, La Jolla, CA; and
| | - Hao Sun
- Department of Medicine, University of California, San Diego, La Jolla, CA; and
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5
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Linares R, Gutiérrez A, Márquez-Galera Á, Caparrós E, Aparicio JR, Madero L, Payá A, López-Atalaya JP, Francés R. Transcriptional regulation of chemokine network by biologic monotherapy in ileum of patients with Crohn’s disease. Pharmacotherapy 2022; 147:112653. [DOI: 10.1016/j.biopha.2022.112653] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 01/13/2022] [Accepted: 01/16/2022] [Indexed: 11/02/2022]
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6
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Wiendl M, Becker E, Müller TM, Voskens CJ, Neurath MF, Zundler S. Targeting Immune Cell Trafficking - Insights From Research Models and Implications for Future IBD Therapy. Front Immunol 2021; 12:656452. [PMID: 34017333 PMCID: PMC8129496 DOI: 10.3389/fimmu.2021.656452] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2021] [Accepted: 04/16/2021] [Indexed: 12/12/2022] Open
Abstract
Inflammatory bowel diseases (IBDs), including Crohn's disease (CD) and ulcerative colitis (UC) are multifactorial diseases with still unknown aetiology and an increasing prevalence and incidence worldwide. Despite plentiful therapeutic options for IBDs, the lack or loss of response in certain patients demands the development of further treatments to tackle this unmet medical need. In recent years, the success of the anti-α4β7 antibody vedolizumab highlighted the potential of targeting the homing of immune cells, which is now an important pillar of IBD therapy. Due to its complexity, leukocyte trafficking and the involved molecules offer a largely untapped resource for a plethora of potential therapeutic interventions. In this review, we aim to summarise current and future directions of specifically interfering with immune cell trafficking. We will comment on concepts of homing, retention and recirculation and particularly focus on the role of tissue-derived chemokines. Moreover, we will give an overview of the mode of action of drugs currently in use or still in the pipeline, highlighting their mechanisms and potential to reduce disease burden.
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Affiliation(s)
- Maximilian Wiendl
- Department of Medicine 1, Deutsches Zentrum Immuntherapie (DZI), University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Emily Becker
- Department of Medicine 1, Deutsches Zentrum Immuntherapie (DZI), University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Tanja M. Müller
- Department of Medicine 1, Deutsches Zentrum Immuntherapie (DZI), University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Caroline J. Voskens
- Department of Dermatology, University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Markus F. Neurath
- Department of Medicine 1, Deutsches Zentrum Immuntherapie (DZI), University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Sebastian Zundler
- Department of Medicine 1, Deutsches Zentrum Immuntherapie (DZI), University Hospital Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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7
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Van der Weken H, Cox E, Devriendt B. Advances in Oral Subunit Vaccine Design. Vaccines (Basel) 2020; 9:1. [PMID: 33375151 PMCID: PMC7822154 DOI: 10.3390/vaccines9010001] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 12/17/2020] [Accepted: 12/19/2020] [Indexed: 02/06/2023] Open
Abstract
Many pathogens invade the host at the intestinal surface. To protect against these enteropathogens, the induction of intestinal secretory IgA (SIgA) responses is paramount. While systemic vaccination provides strong systemic immune responses, oral vaccination is the most efficient way to trigger protective SIgA responses. However, the development of oral vaccines, especially oral subunit vaccines, is challenging due to mechanisms inherent to the gut. Oral vaccines need to survive the harsh environment in the gastrointestinal tract, characterized by low pH and intestinal proteases and need to reach the gut-associated lymphoid tissues, which are protected by chemical and physical barriers that prevent efficient uptake. Furthermore, they need to surmount default tolerogenic responses present in the gut, resulting in suppression of immunity or tolerance. Several strategies have been developed to tackle these hurdles, such as delivery systems that protect vaccine antigens from degradation, strong mucosal adjuvants that induce robust immune responses and targeting approaches that aim to selectively deliver vaccine antigens towards specific immune cell populations. In this review, we discuss recent advances in oral vaccine design to enable the induction of robust gut immunity and highlight that the development of next generation oral subunit vaccines will require approaches that combines these solutions.
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Affiliation(s)
| | | | - Bert Devriendt
- Department of Virology, Parasitology and Immunology, Ghent University, Salisburylaan 133, 9820 Merelbeke, Belgium; (H.V.d.W.); (E.C.)
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8
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Zhu Q, Pan QZ, Zhong AL, Hu H, Zhao JJ, Tang Y, Hu WM, Li M, Weng DS, Chen MY, Ma G, Xia JC. Annexin A3 upregulates the infiltrated neutrophil-lymphocyte ratio to remodel the immune microenvironment in hepatocellular carcinoma. Int Immunopharmacol 2020; 89:107139. [PMID: 33191179 DOI: 10.1016/j.intimp.2020.107139] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 10/15/2020] [Accepted: 10/25/2020] [Indexed: 12/17/2022]
Abstract
Accumulating evidence has indicated that inflammation is required for the initiation and progression of hepatocellular carcinoma (HCC). The annexin family protein, which has a highly similar structure, has been demonstrated to participate in pro- or anti-inflammatory regulation in the developing of tumours. However, the potential effects of ANXA3 in the immune microenvironment of HCC remain unknown. In present study, we found that increased ANXA3 expression is associated with a higher infiltrated neutrophil-lymphocyte ratio (iNLR) in HCC. Moreover, HCC patients with a high iNLR and high ANXA3 expression confer the highest risk of death. ANXA3 can be detected in both cell lysates and culture supernatants. However, the secretory ANXA3 did not directly regulate the iNLR. Further study demonstrated that ANXA3 upregulated the iNLR by inducing chemokine CXCL8 and CCL25 release from HCC cells. We further confirmed that ANXA3 promotes tumourigenesis and detected the same associations between ANXA3 and the iNLR or chemokines in vivo. Our findings indicate that ANXA3 regulates the chemokine to remodel the iNLR and promotes tumourigenicity in HCC. These results further expanded our understanding of ANXA3 in the microenvironment of HCC and might provide novel targets for the investigation of molecular treatments for HCC patients.
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Affiliation(s)
- Qian Zhu
- State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center for Cancer Medicine; Department of Intensive Care Unit, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong 510060, PR China
| | - Qiu-Zhong Pan
- State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center for Cancer Medicine; Department of Biotherapy, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong 510060, PR China
| | - Ai-Lin Zhong
- Office of International Exchange and Cooperation, Guangzhou University of Chinese Medicine, Guangzhou, Guangdong 510006, PR China
| | - Hao Hu
- Department of Radiation Therapy, General Hospital of Southern Theatre Command, Guangzhou, Guangdong 510010, PR China
| | - Jing-Jing Zhao
- State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center for Cancer Medicine; Department of Biotherapy, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong 510060, PR China
| | - Yan Tang
- State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center for Cancer Medicine; Department of Biotherapy, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong 510060, PR China
| | - Wan-Ming Hu
- State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center for Cancer Medicine; Department of Pathology, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong 510060, PR China
| | - Min Li
- State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center for Cancer Medicine; Department of Pathology, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong 510060, PR China
| | - De-Sheng Weng
- State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center for Cancer Medicine; Department of Biotherapy, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong 510060, PR China
| | - Ming-Yuan Chen
- State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center for Cancer Medicine; Department of Nasopharyngeal Carcinoma, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong 510060, PR China
| | - Gang Ma
- State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center for Cancer Medicine; Department of Intensive Care Unit, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong 510060, PR China
| | - Jian-Chuan Xia
- State Key Laboratory of Oncology in Southern China, Collaborative Innovation Center for Cancer Medicine; Department of Biotherapy, Sun Yat-Sen University Cancer Center, Guangzhou, Guangdong 510060, PR China.
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9
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Kim SM, Park M, Yee SM, Ji KY, Lee EH, Nguyen TV, Nguyen THL, Jang J, Kim EM, Choi HR, Yun CH, Kang HS. Axl is a key regulator of intestinal γδ T-cell homeostasis. FASEB J 2019; 33:13386-13397. [DOI: 10.1096/fj.201901356r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
- Su-Man Kim
- School of Biological Sciences and Technology, Chonnam National University, Gwangju, South Korea
| | - Min Park
- School of Biological Sciences and Technology, Chonnam National University, Gwangju, South Korea
| | - Su-Min Yee
- School of Biological Sciences and Technology, Chonnam National University, Gwangju, South Korea
| | - Kon-Young Ji
- School of Biological Sciences and Technology, Chonnam National University, Gwangju, South Korea
| | - Eun-Hee Lee
- Deagu-Gyeongbuk Medical Innovation Foundation, Daegu, South Korea
| | - Thi-Van Nguyen
- School of Biological Sciences and Technology, Chonnam National University, Gwangju, South Korea
| | - Thi Hong-Loan Nguyen
- School of Biological Sciences and Technology, Chonnam National University, Gwangju, South Korea
| | - Jin Jang
- School of Biological Sciences and Technology, Chonnam National University, Gwangju, South Korea
| | - Eun-Mi Kim
- Predictive Model Research Center, Korea Institute of Toxicology, Daejeon, South Korea
| | - Ha-Rim Choi
- Department of Nursing, Nambu University, Gwangju, South Korea
| | - Chul-Ho Yun
- School of Biological Sciences and Technology, Chonnam National University, Gwangju, South Korea
| | - Hyung-Sik Kang
- School of Biological Sciences and Technology, Chonnam National University, Gwangju, South Korea
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10
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Trivedi PJ, Adams DH. Chemokines and Chemokine Receptors as Therapeutic Targets in Inflammatory Bowel Disease; Pitfalls and Promise. J Crohns Colitis 2018; 12:S641-S652. [PMID: 30137309 PMCID: PMC6104621 DOI: 10.1093/ecco-jcc/jjx145] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The principal targets for anti-chemokine therapy in inflammatory bowel disease (IBD) have been the receptors CCR9 and CXCR3 and their respective ligands CCL25 and CXCL10. More recently CCR6 and its ligand CCL20 have also received attention, the expression of the latter in enterocytes being manipulated through Smad7 signalling. These pathways, selected based on their fundamental role in regulating mucosal immunity, have led to the development of several therapeutic candidates that have been tested in early phase clinical trials with variable clinical efficacy. In this article, we appraise the status of chemokine-directed therapy in IBD, review recent developments, and nominate future areas for therapeutic focus.
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Affiliation(s)
- Palak J Trivedi
- National Institute for Health Research (NIHR) Birmingham, Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, UK
- Liver Unit, University Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Hospital Birmingham, Birmingham, UK
- Department of Gastroenterology, University Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Hospital Birmingham, Birmingham, UK
- Centre for Rare Diseases, Institute of Translational Medicine, University of Birmingham, Birmingham, UK
| | - David H Adams
- National Institute for Health Research (NIHR) Birmingham, Institute of Immunology and Immunotherapy, University of Birmingham, Birmingham, UK
- Liver Unit, University Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Hospital Birmingham, Birmingham, UK
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11
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Laufer JM, Legler DF. Beyond migration-Chemokines in lymphocyte priming, differentiation, and modulating effector functions. J Leukoc Biol 2018; 104:301-312. [PMID: 29668063 DOI: 10.1002/jlb.2mr1217-494r] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 03/08/2018] [Accepted: 03/12/2018] [Indexed: 02/06/2023] Open
Abstract
Chemokines and their receptors coordinate the positioning of leukocytes, and lymphocytes in particular, in space and time. Discrete lymphocyte subsets, depending on their activation and differentiation status, express various sets of chemokine receptors to be recruited to distinct tissues. Thus, the network of chemokines and their receptors ensures the correct localization of specialized lymphocyte subsets within the appropriate microenvironment enabling them to search for cognate antigens, to become activated, and to fulfill their effector functions. The chemokine system therefore is vital for the initiation as well as the regulation of immune responses to protect the body from pathogens while maintaining tolerance towards self. Besides the well investigated function of orchestrating directed cell migration, chemokines additionally act on lymphocytes in multiple ways to shape immune responses. In this review, we highlight and discuss the role of chemokines and chemokine receptors in controlling cell-to-cell contacts required for lymphocyte arrest on endothelial cells and immunological synapse formation, in lymphocyte priming and differentiation, survival, as well as in modulating effector functions.
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Affiliation(s)
- Julia M Laufer
- Biotechnology Institute Thurgau (BITg), University of Konstanz, Kreuzlingen, Switzerland.,Konstanz Research School Chemical Biology, University of Konstanz, Konstanz, Germany
| | - Daniel F Legler
- Biotechnology Institute Thurgau (BITg), University of Konstanz, Kreuzlingen, Switzerland.,Konstanz Research School Chemical Biology, University of Konstanz, Konstanz, Germany
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12
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Weingrill RB, Hoshida MS, Martinhago CD, Correa-Silva S, Cardoso E, Palmeira P, Marinho CRF, Bevilacqua E. Chemokine (C-C motif) ligand 25 expressed by trophoblast cells and leukocytes bearing its receptor Ccr9: An alliance during embryo implantation? Am J Reprod Immunol 2017; 79. [PMID: 29154408 DOI: 10.1111/aji.12783] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 10/19/2017] [Indexed: 12/17/2022] Open
Abstract
PROBLEM We hypothesized that trophoblast expression of Ccl25 attracts a specific leukocyte cell population to the implantation site for local regulation. METHOD OF STUDY Mice blastocysts, ectoplacental cones, and decidua at gestational days 3.5-7.5 were evaluated for Ccl25 and Ccr9 expressions. Peripheral availability and characterization of Ccr9+ leukocytes were determined by flow cytometry. Leukocyte chemotaxis was assessed in the presence of Ccl25 recombinant protein and embryos using antisense oligomers (ODNs) to Ccl25 and Ccr9 neutralizing antibody. RESULTS Ccl25 was expressed by embryonic cells, whereas Ccr9 expression was strong at the maternal compartment and in PBMC. Immunolocalization confirmed this expression. In vitro, chemotaxis assays showed that the embryonic Ccl25 signals to Ccr9+ PBMCs. Maternal Ccr9+α4β7+ monocytes switch from an anti-inflammatory phenotype (F4/80+11b+Ly6C-TGF-β+ cells, pre-implantation) to an inflammatory profile (F4/80+11b+Ly6C+TNF-α+ cells, post-implantation). CONCLUSION Our data support the establishment of a CCL25/CCR9-axis at the maternal-fetal interface in mice, which may be involved in immune regulatory mechanisms during embryo implantation.
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Affiliation(s)
- Rodrigo Barbano Weingrill
- Department of Cellular and Developmental Biology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Mara S Hoshida
- Department of Obstetrics and Gynecology, Laboratory of Medical Investigation, School of Medicine, University of São Paulo, São Paulo, Brazil
| | | | - Simone Correa-Silva
- Department of Cellular and Developmental Biology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Elaine Cardoso
- Department of Cellular and Developmental Biology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
| | - Patrícia Palmeira
- Department of Pediatrics, Laboratory of Medical Investigation, School of Medicine, University of São Paulo, São Paulo, Brazil
| | | | - Estela Bevilacqua
- Department of Cellular and Developmental Biology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brazil
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13
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Chemokine treatment rescues profound T-lineage progenitor homing defect after bone marrow transplant conditioning in mice. Blood 2014; 124:296-304. [PMID: 24876562 DOI: 10.1182/blood-2014-01-552794] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Development of T cells in the thymus requires continuous importation of T-lineage progenitors from the bone marrow via the circulation. Following bone marrow transplant, recovery of a normal peripheral T-cell pool depends on production of naïve T cells in the thymus; however, delivery of progenitors to the thymus limits T-lineage reconstitution. Here, we examine homing of intravenously delivered progenitors to the thymus following irradiation and bone marrow reconstitution. Surprisingly, following host conditioning by irradiation, we find that homing of lymphoid-primed multipotent progenitors and common lymphoid progenitors to the thymus decreases more than 10-fold relative to unirradiated mice. The reduction in thymic homing in irradiated mice is accompanied by a significant reduction in CCL25, an important chemokine ligand for thymic homing. We show that pretreatment of bone marrow progenitors with CCL25 and CCL21 corrects the defect in thymic homing after irradiation and promotes thymic reconstitution. These data suggest new therapeutic approaches to promote T-cell regeneration.
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14
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Ullah M, Eucker J, Sittinger M, Ringe J. Mesenchymal stem cells and their chondrogenic differentiated and dedifferentiated progeny express chemokine receptor CCR9 and chemotactically migrate toward CCL25 or serum. Stem Cell Res Ther 2013; 4:99. [PMID: 23958031 PMCID: PMC3854782 DOI: 10.1186/scrt310] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2013] [Accepted: 08/12/2013] [Indexed: 12/16/2022] Open
Abstract
Introduction Guided migration of chondrogenically differentiated cells has not been well studied, even though it may be critical for growth, repair, and regenerative processes. The chemokine CCL25 is believed to play a critical role in the directional migration of leukocytes and stem cells. To investigate the motility effect of serum- or CCL25-mediated chemotaxis on chondrogenically differentiated cells, mesenchymal stem cells (MSCs) were induced to chondrogenic lineage cells. Methods MSC-derived chondrogenically differentiated cells were characterized for morphology, histology, immunohistochemistry, quantitative polymerase chain reaction (qPCR), surface profile, and serum- or CCL25-mediated cell migration. Additionally, the chemokine receptor, CCR9, was examined in different states of MSCs. Results The chondrogenic differentiated state of MSCs was positive for collagen type II and Alcian blue staining, and showed significantly upregulated expression of COL2A1and SOX9, and downregulated expression of CD44, CD73, CD90, CD105 and CD166, in contrast to the undifferentiated and dedifferentiated states of MSCs. For the chondrogenic differentiated, undifferentiated, and dedifferentiated states of MSCs, the serum-mediated chemotaxis was in a percentage ratio of 33%:84%:85%, and CCL25-mediated chemotaxis was in percentage ratio of 12%:14%:13%, respectively. On the protein level, CCR9, receptor of CCL25, was expressed in the form of extracellular and intracellular domains. On the gene level, qPCR confirmed the expression of CCR9 in different states of MSCs. Conclusions CCL25 is an effective cue to guide migration in a directional way. In CCL25-mediated chemotaxis, the cell-migration rate was almost the same for different states of MSCs. In serum-mediated chemotaxis, the cell-migration rate of chondrogenically differentiated cells was significantly lower than that in undifferentiated or dedifferentiated cells. Current knowledge of the surface CD profile and cell migration could be beneficial for regenerative cellular therapies.
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Costa MFS, Bornstein VU, Candéa AL, Henriques-Pons A, Henriques MG, Penido C. CCL25 induces α₄β₇ integrin-dependent migration of IL-17⁺ γδ T lymphocytes during an allergic reaction. Eur J Immunol 2012; 42:1250-60. [PMID: 22539297 DOI: 10.1002/eji.201142021] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Herein, we provide evidence that during allergic inflammation, CCL25 induces the selective migration of IL-17(+) γδ T cells mediated by α(4) β(7) integrin. Intrapleural injection of CCL25 into ovalbumin (OVA)-immunized C57BL/6 mice triggered the accumulation of γδ T lymphocytes expressing CCR9 (CCL25 receptor) and α(4) β(7) integrin in the pleura, but failed to attract αβ T lymphocytes. CCL25 attracted CCR6(+) γδ T cells producing IL-17 (but not IFN-γ or IL-4). OVA challenge triggered increased production of CCL25 followed by the accumulation of CCR9(+) , α(4) β(7) (+) , and CCR6(+) /IL-17(+) γδ T cells into the pleural cavities of OVA-immunized mice, which was inhibited by the in vivo neutralization of CCL25. The in vivo blockade of α(4) β(7) integrin also inhibited the migration of IL-17(+) γδ T lymphocytes (but not of αβ T lymphocytes) into mouse pleura after OVA challenge, suggesting that the CCL25/α(4) β(7) integrin pathway is selective for γδ T cells. In addition, α(4) β(7) integrin blockade impaired the in vitro transmigration of γδ T cells across endothelium (which expresses α(4) β(7) ligands VCAM-1 and MadCAM-1), which was induced by CCL25 and by cell-free pleural washes recovered from OVA-challenged mice. Our results reveal that during an allergic reaction, CCL25 drives IL-17(+) γδ T-cell mobilization to inflamed tissue via α(4) β(7) integrin and modulates IL-17 levels.
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Affiliation(s)
- Maria F S Costa
- Laboratório de Farmacologia Aplicada, Farmanguinhos, Fundação Oswaldo Cruz, Rio de Janeiro, Brazil
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16
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Abstract
It has been well established that integrins mediate cell-cell and cell-matrix adhesion and play crucial roles in the immune system such as leukocyte-endothelium interactions, immune synapse formation, and effector functions. Since the discovery that integrins undergo dynamic changes of adhesive activities in response to external stimuli, intensive studies have been conducted to elucidate the signaling events that control the activation of integrins (inside-out signaling) and signaling events from the induced integrin-dependent adhesion (outside-in signaling). The molecular characterization of these signaling pathways highlights the importance of integrins as bidirectional signaling receptors. The characteristics of integrin signaling are best exemplified in the immune system. This chapter highlights the recent studies of intracellular signaling pathways that regulate integrins in immunological contexts.
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Affiliation(s)
- Tatsuo Kinashi
- Department of Molecular Genetics, Institute of Biomedical Science, Kansai Medical University, Osaka, Japan.
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17
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Chemokine triggered integrin activation and actin remodeling events guiding lymphocyte migration across vascular barriers. Exp Cell Res 2011; 317:632-41. [PMID: 21376176 DOI: 10.1016/j.yexcr.2010.12.007] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2010] [Revised: 12/07/2010] [Accepted: 12/07/2010] [Indexed: 01/13/2023]
Abstract
Chemokine signals activate leukocyte integrins and actin remodeling machineries critical for leukocyte adhesion and motility across vascular barriers. The arrest of leukocytes at target blood vessel sites depends on rapid conformational activation of their α4 and β2 integrins by the binding of endothelial-displayed chemokines to leukocyte Gi-protein coupled receptors (GPCRs). A universal regulator of this event is the integrin-actin adaptor, talin1. Chemokine-stimulated GPCRs can transmit within fractions of seconds signals via multiple Rho GTPases, which locally raise plasma membrane levels of the talin activating phosphatidyl inositol, PtdIns(4,5)P2 (PIP2). Additional pools of GPCR stimulated Rac-1 and Rap-1 GTPases together with GPCR stimulated PLC and PI3K family members regulate the turnover of focal contacts of leukocyte integrins, induce the collapse of leukocyte microvilli, and promote polarized leukocyte crawling in search of exit cues. Concomitantly, other leukocyte GTPases trigger invasive protrusions into and between endothelial cells in search of basolateral chemokine exit cues. We will review here major findings and open questions related to these sequential guiding activities of endothelial presented chemokines, focusing mainly on lymphocyte-endothelial interactions as a paradigm for other leukocytes.
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18
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Gameiro J, Nagib P, Verinaud L. The thymus microenvironment in regulating thymocyte differentiation. Cell Adh Migr 2010; 4:382-90. [PMID: 20418658 DOI: 10.4161/cam.4.3.11789] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The thymus plays a crucial role in the development of T lymphocytes by providing an inductive microenvironment in which committed progenitors undergo proliferation, T-cell receptor gene rearrangements and thymocyte differentiate into mature T cells. The thymus microenvironment forms a complex network of interaction that comprises non lymphoid cells (e.g., thymic epithelial cells, TEC), cytokines, chemokines, extracellular matrix elements (ECM), matrix metalloproteinases and other soluble proteins. The thymic epithelial meshwork is the major component of the thymic microenvironment, both morphologically and phenotypically limiting heterogeneous regions in thymic lobules and fulfilling an important role during specific stages of T-cell maturation. The process starts when bone marrow-derived lymphocyte precursors arrive at the outer cortical region of the thymic gland and begin to mature into functional T lymphocytes that will finally exit the thymus and populate the peripheral lymphoid organs. During their journey inside the thymus, thymocytes must interact with stromal cells (and their soluble products) and extracellular matrix proteins to receive appropriate signals for survival, proliferation and differentiation. The crucial components of the thymus microenvironment, and their complex interactions during the T-cell maturation process are summarized here with the objective of contributing to a better understanding of the function of the thymus, as well as assisting in the search for new therapeutic approaches to improve the immune response in various pathological conditions.
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Affiliation(s)
- Jacy Gameiro
- Department of Parasitology, Microbiology and Immunology, Federal University of Juiz de Fora, Juiz de Fora, Minas Gerais, Brazil
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19
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Functional genomic analysis of peripheral blood during early acute renal allograft rejection. Transplantation 2010; 88:942-51. [PMID: 19935467 DOI: 10.1097/tp.0b013e3181b7ccc6] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
BACKGROUND Acute graft rejection is an important clinical problem in renal transplantation and an adverse predictor for long-term graft survival. Peripheral blood biomarkers that provide evidence of early graft rejection may offer an important option for posttransplant monitoring, optimize the utility of graft biopsy, and permit timely and effective therapeutic intervention to minimize the graft damage. METHODS In this feasibility study (n=58), we have used gene expression profiling in a case-control design to compare whole blood samples between normal subjects (n=20) and patients with (n=11) or without (n=22) biopsy-confirmed acute rejection (BCAR) or borderline changes (n=5). RESULTS A total of 183 probe sets representing 160 genes were differentially expressed (false discovery rate [FDR] <0.01) between subjects with or without BCAR, from which linear discriminant analysis and cross-validation identified an initial gene signature of 24 probe sets, and a more refined set of 11 probe sets found to classify subject samples correctly. Cross-validation suggested an out-of-sample sensitivity of 73% and specificity of 91% for identification of samples with or without BCAR. An increase in classifier gene expression correlated closely with acute rejection during the first 3 months posttransplant. Biological evaluation indicated that the differentially expressed genes encompassed processes related to immune response, signal transduction, and cytoskeletal reorganization. CONCLUSION Preliminary evidence indicates that gene expression in the peripheral blood may yield a relevant measure for the occurrence of BCAR and offer a potential tool for immunologic monitoring. These results now require confirmation in a larger cohort.
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20
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Rap1 controls lymphocyte adhesion cascade and interstitial migration within lymph nodes in RAPL-dependent and -independent manners. Blood 2009; 115:804-14. [PMID: 19965628 DOI: 10.1182/blood-2009-03-211979] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The small GTPase Rap1 and its effector RAPL regulate lymphocyte adhesion and motility. However, their precise regulatory roles in the adhesion cascade preceding entry into lymph nodes and during interstitial migration are unclear. Here, we show that Rap1 is indispensably required for the chemokine-triggered initial arrest step of rolling lymphocytes through LFA-1, whereas RAPL is not involved in rapid arrest. RAPL and talin play a critical role in stabilizing lymphocyte arrest to the endothelium of blood vessels under flow or to the high endothelial venules of peripheral lymph nodes in vivo. Further, mutagenesis and peptide studies suggest that release of a trans-acting restraint from the beta2 cytoplasmic region of LFA-1 is critical for Rap1-dependent initial arrest. Rap1 or RAPL deficiency severely impaired lymphocyte motility over lymph node stromal cells in vitro, and RAPL deficiency impaired high-velocity directional movement within lymph nodes. These findings reveal the several critical steps of Rap1, which are RAPL-dependent and -independent, in lymphocyte trafficking.
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21
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Abstract
Integrins are the principal cell adhesion receptors that mediate leukocyte migration and activation in the immune system. These receptors signal bidirectionally through the plasma membrane in pathways referred to as inside-out and outside-in signaling. Each of these pathways is mediated by conformational changes in the integrin structure. Such changes allow high-affinity binding of the receptor with counter-adhesion molecules on the vascular endothelium or extracellular matrix and lead to association of the cytoplasmic tails of the integrins with intracellular signaling molecules. Leukocyte functional responses resulting from outside-in signaling include migration, proliferation, cytokine secretion, and degranulation. Here, we review the key signaling events that occur in the inside-out versus outside-in pathways, highlighting recent advances in our understanding of how integrins are activated by a variety of stimuli and how they mediate a diverse array of cellular responses.
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Affiliation(s)
- Clare L Abram
- Program in Immunology, Department of Laboratory Medicine, University of California, San Francisco, California 94143-0451, USA
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22
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Nolz JC, Nacusi LP, Segovis CM, Medeiros RB, Mitchell JS, Shimizu Y, Billadeau DD. The WAVE2 complex regulates T cell receptor signaling to integrins via Abl- and CrkL-C3G-mediated activation of Rap1. ACTA ACUST UNITED AC 2008; 182:1231-44. [PMID: 18809728 PMCID: PMC2542481 DOI: 10.1083/jcb.200801121] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
WAVE2 regulates T cell receptor (TCR)–stimulated actin cytoskeletal dynamics leading to both integrin clustering and affinity maturation. Although WAVE2 mediates integrin affinity maturation by recruiting vinculin and talin to the immunological synapse in an Arp2/3-dependent manner, the mechanism by which it regulates integrin clustering is unclear. We show that the Abl tyrosine kinase associates with the WAVE2 complex and TCR ligation induces WAVE2-dependent membrane recruitment of Abl. Furthermore, we show that WAVE2 regulates TCR-mediated activation of the integrin regulatory guanosine triphosphatase Rap1 via the recruitment and activation of the CrkL–C3G exchange complex. Moreover, we demonstrate that although Abl does not regulate the recruitment of CrkL–C3G into the membrane, it does affect the tyrosine phosphorylation of C3G, which is required for its guanine nucleotide exchange factor activity toward Rap1. This signaling node regulates not only TCR-stimulated integrin clustering but also affinity maturation. These findings identify a previously unknown mechanism by which the WAVE2 complex regulates TCR signaling to Rap1 and integrin activation.
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Affiliation(s)
- Jeffrey C Nolz
- Department of Immunology, College of Medicine, Mayo Clinic, Rochester, MN 55905, USA
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Banerjee ER, Latchman YE, Jiang Y, Priestley GV, Papayannopoulou T. Distinct changes in adult lymphopoiesis in Rag2-/- mice fully reconstituted by alpha4-deficient adult bone marrow cells. Exp Hematol 2008; 36:1004-13. [PMID: 18468770 DOI: 10.1016/j.exphem.2008.03.008] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2008] [Revised: 03/06/2008] [Accepted: 03/07/2008] [Indexed: 12/17/2022]
Abstract
OBJECTIVE alpha4 Integrins are major players in lymphoid cell trafficking and immune responses. However, their importance in lymphoid reconstitution and function, studied by antibody blockade or in genetic models of chimeric animals with alpha4(KO) embryonic stem (ES) cells, competitive repopulation experiments with fetal liver(KO) cells, or in beta1/beta7 doubly-deficient mice has yielded disparate conclusions. MATERIALS AND METHODS To study the role of alpha4 integrin (alpha4beta1, alpha4beta7) during adult life, we transplanted lethally irradiated Rag2(-/-) mice with alpha4(Delta/Delta) or alpha4(f/f) adult bone marrow (BM) cells and evaluated recipients at several points after transplantation. RESULTS Lymphomyeloid repopulation (8 months later) was entirely donor-derived in all recipients, and novel insights regarding lymphoid reconstitution and function were revealed. Thymic repopulation was impaired in all alpha4(Delta/Delta) recipients, likely because of homing defects of BM-derived progenitors, although a role of alpha4 integrin in intrathymic expansion/maturation of T cells cannot be excluded; reconstitution of gut lymphoid tissue was also greatly diminished because of homing defects of alpha4(Delta/Delta) cells; impaired immunoglobulin (Ig) M and IgE, but normal IgG responses were seen, suggesting compromised initial B-/T-cell interactions, whereas interferon-gamma production from ovalbumin-stimulated cells was increased, possibly reflecting a bias against Th2 stimulation. CONCLUSION These data complement previous observations by defending the role of alpha4 integrin in thymic and gut lymphoid tissue homing, and by strengthening evidence of attenuated B-cell responses in alpha4-deficient mice.
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Affiliation(s)
- Ena R Banerjee
- Department of Medicine, Division of Hematology, University of Washington, Seattle, WA 98195-7710, USA
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Pittet MJ, Mempel TR. Regulation of T-cell migration and effector functions: insights from in vivo imaging studies. Immunol Rev 2008; 221:107-29. [PMID: 18275478 DOI: 10.1111/j.1600-065x.2008.00584.x] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Studies of the immune system are providing us with ever more detailed information on the cellular and molecular mechanisms that underlie our evolutionarily conserved ability to fend off infectious pathogens. Progress has probably been fastest at two levels: the various basic biological functions of isolated cells on one side and the significance of individual molecules or cells to the organism as a whole on the other. In both cases, direct phenomenological observation has been an invaluable methodological approach. Where we know least is the middle ground, i.e. how immune functions are integrated through the dynamic interplay of immune cell subsets within the organism. Most of our knowledge in this area has been obtained through inference from static snapshots of dynamic processes, such as histological sections, or from surrogate cell co-culture models. The latter are employed under the assumption that an in vivo equivalent exists for each type of cellular contact artificially enforced in absence of anatomical compartmentalization. In this review, we summarize recent insights on migration and effector functions of T cells, focusing on observations gained from their dynamic microscopic visualization in physiological tissue environments.
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Affiliation(s)
- Mikael J Pittet
- Center for Systems Biology, Massachusetts General Hospital and Harvard Medical School, Simches Research Building, Boston, MA 02129, USA
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25
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Abstract
More than a quarter of a century has passed since the observation that T cells rapidly polarize their actin and microtubule cytoskeletal systems toward antigen-presenting cells during activation. Since this initial discovery, several receptors on T cells (e.g., T cell receptor [TCR], co-receptors, integrins, and chemokine receptors) have been identified to regulate these two cytoskeletal networks through complex signaling pathways, which are still being elucidated. There is now an undeniable body of biochemical, pharmacological, and genetic evidence indicating that regulators of actin and microtubule dynamics are crucial for T cell activation and effector functions. In fact, the actin cytoskeleton participates in the initial clustering of TCR-major histocompatibility complex or peptide complexes, formation and stabilization of the immune synapse, integrin-mediated adhesion, and receptor sequestration, whereas both the actin and microtubule cytoskeletons regulate the establishment of cell polarity, cell migration, and directed secretion of cytokines and cytolytic granules. Over the past several years, we have begun to more thoroughly understand the contributions of specific actin-regulatory and actin-nucleating proteins that govern these processes. Herein, we discuss our current understanding of how activating receptors on T lymphocytes regulate the actin and microtubule cytoskeletons, and how in turn, these distinct but integrated cytoskeletal networks coordinate T cell immune responses.
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