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Johansen KH, Golec DP, Thomsen JH, Schwartzberg PL, Okkenhaug K. PI3K in T Cell Adhesion and Trafficking. Front Immunol 2021; 12:708908. [PMID: 34421914 PMCID: PMC8377255 DOI: 10.3389/fimmu.2021.708908] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 07/19/2021] [Indexed: 12/12/2022] Open
Abstract
PI3K signalling is required for activation, differentiation, and trafficking of T cells. PI3Kδ, the dominant PI3K isoform in T cells, has been extensively characterised using PI3Kδ mutant mouse models and PI3K inhibitors. Furthermore, characterisation of patients with Activated PI3K Delta Syndrome (APDS) and mouse models with hyperactive PI3Kδ have shed light on how increased PI3Kδ activity affects T cell functions. An important function of PI3Kδ is that it acts downstream of TCR stimulation to activate the major T cell integrin, LFA-1, which controls transendothelial migration of T cells as well as their interaction with antigen-presenting cells. PI3Kδ also suppresses the cell surface expression of CD62L and CCR7 which controls the migration of T cells across high endothelial venules in the lymph nodes and S1PR1 which controls lymph node egress. Therefore, PI3Kδ can control both entry and exit of T cells from lymph nodes as well as the recruitment to and retention of T cells within inflamed tissues. This review will focus on the regulation of adhesion receptors by PI3Kδ and how this contributes to T cell trafficking and localisation. These findings are relevant for our understanding of how PI3Kδ inhibitors may affect T cell redistribution and function.
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Affiliation(s)
- Kristoffer H Johansen
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom.,Laboratory of Immune System Biology, NIAID, NIH, Bethesda, MD, United States
| | - Dominic P Golec
- Laboratory of Immune System Biology, NIAID, NIH, Bethesda, MD, United States
| | - Julie H Thomsen
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | | | - Klaus Okkenhaug
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
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Afzali S, Salehi S, Shahi A, Amirzargar A. B cell modulation strategies in the improvement of transplantation outcomes. Mol Immunol 2020; 125:140-150. [PMID: 32682148 DOI: 10.1016/j.molimm.2020.06.028] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2020] [Revised: 06/19/2020] [Accepted: 06/30/2020] [Indexed: 01/03/2023]
Abstract
Successful transplantation outcome is the final goal in most end stage and nonfunctional organs; however, despite using different therapeutic strategies, antibody-mediated rejection is still a big obstacle. B cells have a key role in transplant rejection by several functions, such as antibody production, antigen presenting, contribution in T cell activation, forming the germinal center, and tertiary lymphoid organs. Therefore, B cells modulation seems to be very crucial in transplant outcome. A double-edged sword function is considered for B cells during transplantation; On the one hand, antibody production against the transplanted organ induces antibody-mediated rejection. On the other hand, IL10 production by regulatory B (Breg) cells induces graft tolerance. Nowadays, several monoclonal antibodies (mAb) are available for B cell modulation that are routinely used in transplant recipients, among which rituximab (anti-CD20 mAb) act in eliminating B cells. However, there are some other monoclonal antibodies, such as epratuzumab and Inotuzumab ozogamicin (IO), which exert anti-CD22 activity, resulting in disruption of B cell functions and induction of tolerance in autoimmune disease or B cell malignancies; that notwithstanding, these mAbs have not yet been tried in transplantation. In this review, we focus on different methods for modulating the activity of B cells as well as induction of Breg cells, aiming to prevent the allograft rejection.
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Affiliation(s)
- Shima Afzali
- Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran; Students' Scientific Research Center, Tehran University of Medical Sciences, Tehran, Iran
| | - Saeedeh Salehi
- Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Abbas Shahi
- Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran
| | - Aliakbar Amirzargar
- Department of Immunology, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran.
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Yang C, Chen X, Wei Z, Xiao J, Chen W, Shang Y, Liu J. Targeting the class IA PI3K isoforms p110α/δ attenuates heart allograft rejection in mice by suppressing the CD4 + T lymphocyte response. Am J Transl Res 2018; 10:1387-1399. [PMID: 29887953 PMCID: PMC5992545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 04/06/2018] [Indexed: 06/08/2023]
Abstract
Acute rejection is the most important factor causing allograft loss, which remains a challenge for patients undergoing organ transplantation. There is considerable evidence indicating that the activity of PI3K and its downstream positive and negative regulators plays a major role in regulating the activation of different subsets of effector CD4+ T cells. Thus, we investigated whether class A PI3Ks are involved in the development of acute allograft rejection, we found that p110α protein expression levels in the allograft group were significantly up-regulated on day 7 post-transplantation, while p110β and p110δ expression was significantly increased on days 5 and 7 post-transplantation. Treatment with PIK and IC but not TGX significantly prolonged allograft survival and altered pathological grades. The percentages of Th1 and Th2, Th17 and Tfh cells/monocytes in the spleens from the IC treatment group were all down-regulated. In contrast, the percentage of Treg cells in the spleens from IC treatment group was remarkably increased. IL-17A and IL-21 and IFN-γ expression levels were significantly decreased in the IC group. Moreover, IC significantly reduced P70 S6 Kinase β and 4E-BP1 protein expression. In conclusion, small-molecule inhibitors of p110δ and p110α suppress acute heart allograft rejection in mice. These inhibitors may play a role in anti-rejection by impacting the phosphorylation and expression of proteins in the AKT/mTOR pathway to modulate CD4+ T cell subsets levels in recipients, reduce proinflammatory factor expression and increase anti-inflammatory cytokine expression. These findings indicate that some small-molecule inhibitors of p110 can serve as novel targets in acute allograft rejection treatment.
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Affiliation(s)
- Chuanlei Yang
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and TechnologyWuhan 430022, China
- Department of Cardiovascular Surgery, Wuhan Central Hospital, Tongji Medical College, Huazhong University of Science and TechnologyWuhan, China
| | - Xing Chen
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and TechnologyWuhan 430022, China
| | - Zhanjie Wei
- Department of Cardiovascular Surgery, Wuhan Central Hospital, Tongji Medical College, Huazhong University of Science and TechnologyWuhan, China
| | - Jie Xiao
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and TechnologyWuhan 430022, China
| | - Weiqiang Chen
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and TechnologyWuhan 430022, China
| | - Yuqiang Shang
- Department of Cardiovascular Surgery, Wuhan Central Hospital, Tongji Medical College, Huazhong University of Science and TechnologyWuhan, China
| | - Jinping Liu
- Department of Cardiovascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and TechnologyWuhan 430022, China
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Mauro C, Smith J, Cucchi D, Coe D, Fu H, Bonacina F, Baragetti A, Cermenati G, Caruso D, Mitro N, Catapano AL, Ammirati E, Longhi MP, Okkenhaug K, Norata GD, Marelli-Berg FM. Obesity-Induced Metabolic Stress Leads to Biased Effector Memory CD4 + T Cell Differentiation via PI3K p110δ-Akt-Mediated Signals. Cell Metab 2017; 25:593-609. [PMID: 28190771 PMCID: PMC5355363 DOI: 10.1016/j.cmet.2017.01.008] [Citation(s) in RCA: 107] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 09/29/2016] [Accepted: 01/11/2017] [Indexed: 01/25/2023]
Abstract
Low-grade systemic inflammation associated to obesity leads to cardiovascular complications, caused partly by infiltration of adipose and vascular tissue by effector T cells. The signals leading to T cell differentiation and tissue infiltration during obesity are poorly understood. We tested whether saturated fatty acid-induced metabolic stress affects differentiation and trafficking patterns of CD4+ T cells. Memory CD4+ T cells primed in high-fat diet-fed donors preferentially migrated to non-lymphoid, inflammatory sites, independent of the metabolic status of the hosts. This was due to biased CD4+ T cell differentiation into CD44hi-CCR7lo-CD62Llo-CXCR3+-LFA1+ effector memory-like T cells upon priming in high-fat diet-fed animals. Similar phenotype was observed in obese subjects in a cohort of free-living people. This developmental bias was independent of any crosstalk between CD4+ T cells and dendritic cells and was mediated via direct exposure of CD4+ T cells to palmitate, leading to increased activation of a PI3K p110δ-Akt-dependent pathway upon priming.
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Affiliation(s)
- Claudio Mauro
- William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, EC1M 6BQ, UK.
| | - Joanne Smith
- William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, EC1M 6BQ, UK
| | - Danilo Cucchi
- William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, EC1M 6BQ, UK; Istituto Pasteur, Fondazione Cenci Bolognetti, Rome 00161, Italy
| | - David Coe
- William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, EC1M 6BQ, UK
| | - Hongmei Fu
- William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, EC1M 6BQ, UK
| | - Fabrizia Bonacina
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milan 9-20133, Italy
| | - Andrea Baragetti
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milan 9-20133, Italy
| | - Gaia Cermenati
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milan 9-20133, Italy
| | - Donatella Caruso
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milan 9-20133, Italy
| | - Nico Mitro
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milan 9-20133, Italy
| | - Alberico L Catapano
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milan 9-20133, Italy; IRCCS Multimedica, Milan 2-242091, Italy
| | - Enrico Ammirati
- De Gasperis Cardio Center, Niguarda Ca' Granda Hospital, Milan 3-20162, Italy
| | - Maria P Longhi
- William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, EC1M 6BQ, UK
| | - Klaus Okkenhaug
- Laboratory of Lymphocyte Signalling and Development, Babraham Institute, Cambridge, CB22 3AT, UK
| | - Giuseppe D Norata
- Department of Pharmacological and Biomolecular Sciences, Università degli Studi di Milano, Milan 9-20133, Italy; School of Biomedical Sciences, Curtin Health Innovation Research Institute, Curtin University, Perth, WA 6102, Australia
| | - Federica M Marelli-Berg
- William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, EC1M 6BQ, UK.
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Fu H, Ward EJ, Marelli-Berg FM. Mechanisms of T cell organotropism. Cell Mol Life Sci 2016; 73:3009-33. [PMID: 27038487 PMCID: PMC4951510 DOI: 10.1007/s00018-016-2211-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 03/21/2016] [Accepted: 03/22/2016] [Indexed: 02/06/2023]
Abstract
Protective immunity relies upon T cell differentiation and subsequent migration to target tissues. Similarly, immune homeostasis requires the localization of regulatory T cells (Tregs) to the sites where immunity takes place. While naïve T lymphocytes recirculate predominantly in secondary lymphoid tissue, primed T cells and activated Tregs must traffic to the antigen rich non-lymphoid tissue to exert effector and regulatory responses, respectively. Following priming in draining lymph nodes, T cells acquire the 'homing receptors' to facilitate their access to specific tissues and organs. An additional level of topographic specificity is provided by T cells receptor recognition of antigen displayed by the endothelium. Furthermore, co-stimulatory signals (such as those induced by CD28) have been shown not only to regulate T cell activation and differentiation, but also to orchestrate the anatomy of the ensuing T cell response. We here review the molecular mechanisms supporting trafficking of both effector and regulatory T cells to specific antigen-rich tissues.
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Affiliation(s)
- Hongmei Fu
- William Harvey Research Institute, Heart Centre, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London, EC1M 6BQ, UK
| | - Eleanor Jayne Ward
- William Harvey Research Institute, Heart Centre, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London, EC1M 6BQ, UK
| | - Federica M Marelli-Berg
- William Harvey Research Institute, Heart Centre, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, Charterhouse Square, London, EC1M 6BQ, UK.
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PI3K inhibitors in inflammation, autoimmunity and cancer. Curr Opin Pharmacol 2015; 23:82-91. [PMID: 26093105 PMCID: PMC4518027 DOI: 10.1016/j.coph.2015.05.017] [Citation(s) in RCA: 215] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 05/29/2015] [Indexed: 12/20/2022]
Abstract
The healthy immune system protects against infection and malignant transformation without causing significant damage to host tissues. Immune dysregulation results in diverse pathologies including autoimmune disease, chronic inflammatory disorders, allergies as well as immune deficiencies and cancer. Phosphoinositide 3-kinase (PI3K) signalling has been shown to be a key pathway in the regulation of the immune response and continues to be the focus of intense research. In recent years we have gained detailed understanding of PI3K signalling, and saw the development of potent and highly selective small molecule inhibitors, of which several are currently in clinical trials for the treatment of immune-related disorders and cancer. The role of PI3K signalling in the immune response has been the subject of detailed reviews; here we focus on relevant recent progress in pre-clinical and clinical development of PI3K inhibitors.
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Sido JM, Nagarkatti PS, Nagarkatti M. Δ⁹-Tetrahydrocannabinol attenuates allogeneic host-versus-graft response and delays skin graft rejection through activation of cannabinoid receptor 1 and induction of myeloid-derived suppressor cells. J Leukoc Biol 2015; 98:435-47. [PMID: 26034207 DOI: 10.1189/jlb.3a0115-030rr] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2015] [Accepted: 05/06/2015] [Indexed: 12/18/2022] Open
Abstract
Immune cells have been shown to express cannabinoid receptors and to produce endogenous ligands. Moreover, activation of cannabinoid receptors on immune cells has been shown to trigger potent immunosuppression. Despite such studies, the role of cannabinoids in transplantation, specifically to prevent allograft rejection, has not, to our knowledge, been investigated previously. In the current study, we tested the effect of THC on the suppression of HvGD as well as rejection of skin allografts. To this end, we studied HvGD by injecting H-2(k) splenocytes into H-2(b) mice and analyzing the immune response in the draining ingLNs. THC treatment significantly reduced T cell proliferation and activation in draining LNs of the recipient mice and decreased early stage rejection-indicator cytokines, including IL-2 and IFN-γ. THC treatment also increased the allogeneic skin graft survival. THC treatment in HvGD mice led to induction of MDSCs. Using MDSC depletion studies as well as adoptive transfer experiments, we found that THC-induced MDSCs were necessary for attenuation of HvGD. Additionally, using pharmacological inhibitors of CB1 and CB2 receptors and CB1 and CB2 knockout mice, we found that THC was working preferentially through CB1. Together, our research shows, for the first time to our knowledge, that targeting cannabinoid receptors may provide a novel treatment modality to attenuate HvGD and prevent allograft rejection.
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Affiliation(s)
- Jessica M Sido
- *Department of Pathology, Microbiology, and Immunology, University of South Carolina School of Medicine, Columbia, South Carolina, USA; and William Jennings Bryan Dorn Veterans Affairs Medical Center, Columbia, South Carolina, USA
| | - Prakash S Nagarkatti
- *Department of Pathology, Microbiology, and Immunology, University of South Carolina School of Medicine, Columbia, South Carolina, USA; and William Jennings Bryan Dorn Veterans Affairs Medical Center, Columbia, South Carolina, USA
| | - Mitzi Nagarkatti
- *Department of Pathology, Microbiology, and Immunology, University of South Carolina School of Medicine, Columbia, South Carolina, USA; and William Jennings Bryan Dorn Veterans Affairs Medical Center, Columbia, South Carolina, USA
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An analysis of the global expression of microRNAs in an experimental model of physiological left ventricular hypertrophy. PLoS One 2014; 9:e93271. [PMID: 24751578 PMCID: PMC3994002 DOI: 10.1371/journal.pone.0093271] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 03/03/2014] [Indexed: 01/19/2023] Open
Abstract
Background MicroRNAs (miRs) are a class of small non-coding RNAs that regulate gene expression. Studies of transgenic mouse models have indicated that deregulation of a single miR can induce pathological cardiac hypertrophy and cardiac failure. The roles of miRs in the genesis of physiological left ventricular hypertrophy (LVH), however, are not well understood. Objective To evaluate the global miR expression in an experimental model of exercise-induced LVH. Methods Male Balb/c mice were divided into sedentary (SED) and exercise (EXE) groups. Voluntary exercise was performed on an odometer-monitored metal wheels for 35 days. Various tests were performed after 7 and 35 days of training, including a transthoracic echocardiography, a maximal exercise test, a miR microarray (miRBase v.16) and qRT-PCR analysis. Results The ratio between the left ventricular weight and body weight was increased by 7% in the EXE group at day 7 (p<0.01) and by 11% at day 35 of training (p<0.001). After 7 days of training, the microarray identified 35 miRs that were differentially expressed between the two groups: 20 were up-regulated and 15 were down-regulated in the EXE group compared with the SED group (p = 0.01). At day 35 of training, 25 miRs were differentially expressed: 15 were up-regulated and 10 were decreased in the EXE animals compared with the SED animals (p<0.01). The qRT-PCR analysis demonstrated an increase in miR-150 levels after 35 days and a decrease in miR-26b, miR-27a and miR-143 after 7 days of voluntary exercise. Conclusions We have identified new miRs that can modulate physiological cardiac hypertrophy, particularly miR-26b, -150, -27a and -143. Our data also indicate that previously established regulatory gene pathways involved in pathological LVH are not changed in physiological LVH.
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Steinbach EC, Kobayashi T, Russo SM, Sheikh SZ, Gipson GR, Kennedy ST, Uno JK, Mishima Y, Borst LB, Liu B, Herfarth H, Ting JPY, Sartor RB, Plevy SE. Innate PI3K p110δ regulates Th1/Th17 development and microbiota-dependent colitis. THE JOURNAL OF IMMUNOLOGY 2014; 192:3958-68. [PMID: 24634494 DOI: 10.4049/jimmunol.1301533] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The p110δ subunit of class IA PI3K modulates signaling in innate immune cells. We previously demonstrated that mice harboring a kinase-dead p110δ subunit (p110δ(KD)) develop spontaneous colitis. Macrophages contributed to the Th1/Th17 cytokine bias in p110δ(KD) mice through increased IL-12 and IL-23 expression. In this study, we show that the enteric microbiota is required for colitis development in germfree p110δ(KD) mice. Colonic tissue and macrophages from p110δ(KD) mice produce significantly less IL-10 compared with wild-type mice. p110δ(KD) APCs cocultured with naive CD4+ Ag-specific T cells also produce significantly less IL-10 and induce more IFN-γ- and IL-17A-producing CD4+ T cells compared with wild-type APCs. Illustrating the importance of APC-T cell interactions in colitis pathogenesis in vivo, Rag1(-/-)/p110δ(KD) mice develop mild colonic inflammation and produced more colonic IL-12p40 compared with Rag1(-/-) mice. However, CD4+ CD45RB(high/low) T cell Rag1(-/-)/p110δ(KD) recipient mice develop severe colitis with increased percentages of IFN-γ- and IL-17A-producing lamina propria CD3+D4+ T cells compared with Rag1(-/-) recipient mice. Intestinal tissue samples from patients with Crohn's disease reveal significantly lower expression of PIK3CD compared with intestinal samples from non-inflammatory bowel disease control subjects (p < 0.05). PIK3CD expression inversely correlates with the ratio of IL12B:IL10 expression. In conclusion, the PI3K subunit p110δ controls homeostatic APC-T cell interactions by altering the balance between IL-10 and IL-12/23. Defects in p110δ expression and/or function may underlie the pathogenesis of human inflammatory bowel disease and lead to new therapeutic strategies.
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Affiliation(s)
- Erin C Steinbach
- Department of Microbiology and Immunology, University of North Carolina School of Medicine, Chapel Hill, NC 27599
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Prchal-Murphy M, Putz EM, Freissmuth M, Sexl V, Zebedin-Brandl E. Targeting PI3Kδ: One man's meat is another man's poison. Oncoimmunology 2013; 2:e22272. [PMID: 23482629 PMCID: PMC3583912 DOI: 10.4161/onci.22272] [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] [Indexed: 11/19/2022] Open
Abstract
We have recently uncovered the indispensable role of phosphoinositide-3-kinase δ (PI3Kδ) at different stages of the canonical killing pathway of cytotoxic T lymphocytes (CTLs). The interception of PI3Kδ−conveyed signals has been considered a valuable therapeutic strategy in oncology. However, our observations predict that the benefits of this approach may be limited by a trade-off between direct anticancer effects and an impaired ability of CTLs and NK cells to attack tumor cells.
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Affiliation(s)
- Michaela Prchal-Murphy
- Institute of Pharmacology and Toxicology; Department for Biomedical Science; University of Veterinary Medicine Vienna; Vienna, Austria
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Gamper CJ, Powell JD. All PI3Kinase signaling is not mTOR: dissecting mTOR-dependent and independent signaling pathways in T cells. Front Immunol 2012; 3:312. [PMID: 23087689 PMCID: PMC3466461 DOI: 10.3389/fimmu.2012.00312] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2012] [Accepted: 09/17/2012] [Indexed: 12/14/2022] Open
Abstract
The mechanistic target of rapamycin (mTOR) is emerging as playing a central role in regulating T cell activation, differentiation, and function. mTOR integrates diverse signals from the immune microenvironment to shape the outcome of T cell receptor (TCR) antigen recognition. Phosphatidylinositol 3-kinase (PI3K) enzymes are critical mediators of T cell activation through their generation of the second messenger phosphatidylinositol (3,4,5) triphosphate (PIP3). Indeed, PIP3 generation results in the activation of Protein Kinase B (PKB, also known as AKT), a key activator of mTOR. However, recent genetic studies have demonstrated inconsistencies between PI3K disruption and loss of mTOR expression with regard to the regulation of effector and regulatory T cell homeostasis and function. In this review, we focus on how PI3K activation directs mature CD4 T cell activation and effector function by pathways dependent on and independent of mTOR signaling. Importantly, what has become clear is that targeting both mTOR-dependent and mTOR-independent PI3K-induced signaling distally affords the opportunity for more selective regulation of T cell differentiation and function.
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Putz EM, Prchal-Murphy M, Simma OA, Forster F, Koenig X, Stockinger H, Piekorz RP, Freissmuth M, Müller M, Sexl V, Zebedin-Brandl E. PI3Kδ is essential for tumor clearance mediated by cytotoxic T lymphocytes. PLoS One 2012; 7:e40852. [PMID: 22808277 PMCID: PMC3396622 DOI: 10.1371/journal.pone.0040852] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Accepted: 06/13/2012] [Indexed: 11/19/2022] Open
Abstract
Background PI3Kδ is a lipid kinase of the phosphoinositide 3-kinase class 1A family and involved in early signaling events of leukocytes regulating proliferation, differentiation and survival. Currently, several inhibitors of PI3Kδ are under investigation for the treatment of hematopoietic malignancies. In contrast to the beneficial effect of inhibiting PI3Kδ in tumor cells, several studies reported the requirement of PI3Kδ for the function of immune cells, such as natural killer and T helper cells. Cytotoxic T lymphocytes (CTLs) are essential for tumor surveillance. The scope of this study is to clarify the potential impact of PI3Kδ inhibition on the function of CTLs with emphasis on tumor surveillance. Principal Findings PI3Kδ-deficient mice develop significantly bigger tumors when challenged with MC38 colon adenocarcinoma cells. This defect is accounted for by the fact that PI3Kδ controls the secretory perforin-granzyme pathway as well as the death-receptor pathway of CTL-mediated cytotoxicity, leading to severely diminished cytotoxicity against target cells in vitro and in vivo in the absence of PI3Kδ expression. PI3Kδ-deficient CTLs express low mRNA levels of important components of the cytotoxic machinery, e.g. prf1, grzmA, grzmB, fasl and trail. Accordingly, PI3Kδ-deficient tumor-infiltrating CTLs display a phenotype reminiscent of naïve T cells (CD69lowCD62Lhigh). In addition, electrophysiological capacitance measurements confirmed a fundamental degranulation defect of PI3Kδ−/− CTLs. Conclusion Our results demonstrate that CTL-mediated tumor surveillance is severely impaired in the absence of PI3Kδ and predict that impaired immunosurveillance may limit the effectiveness of PI3Kδ inhibitors in long-term treatment.
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Affiliation(s)
- Eva Maria Putz
- Department for Biomedical Sciences, Institute of Pharmacology and Toxicology, University of Veterinary Medicine Vienna, Vienna, Austria.
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T cell trafficking and metabolism: novel mechanisms and targets for immunomodulation. Curr Opin Pharmacol 2012; 12:452-7. [PMID: 22436327 DOI: 10.1016/j.coph.2012.02.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Revised: 02/22/2012] [Accepted: 02/23/2012] [Indexed: 11/21/2022]
Abstract
Coordinated migratory events by naïve and memory T cells are key to effective immunity. Naïve T cells predominantly recirculate through secondary lymphoid tissue until antigen encounter, while primed T cells efficiently localize to antigen-rich lymphoid and non-lymphoid tissue. Tissue-selective targeting by primed T cells is achieved by a combination of inflammatory signals and tissue-selective homing receptors acquired by T cells during activation and differentiation. A large number of molecular mediators and interactions promoting memory T cell migration to non-lymphoid sites of inflammation have been identified. Recently, additional antigen-driven mechanisms have been proposed, which orchestrate the targeted delivery of memory T cells to antigen-rich tissue. Importantly, recent studies have revealed that the T cell metabolic status influences their differentiation and homing patterns. We here summarize these key observations and discuss their relevance for the manipulation of immune anatomy in therapeutic settings.
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