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Wei X, Jin C, Li D, Wang Y, Zheng S, Feng Q, Shi N, Kong W, Ma X, Wang J. Single-cell transcriptomics reveals CD8 + T cell structure and developmental trajectories in idiopathic pulmonary fibrosis. Mol Immunol 2024; 172:85-95. [PMID: 38936318 DOI: 10.1016/j.molimm.2024.06.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2024] [Revised: 06/20/2024] [Accepted: 06/23/2024] [Indexed: 06/29/2024]
Abstract
Immune cells in the human lung are associated with idiopathic pulmonary fibrosis. However, the contribution of different immune cell subpopulations to the pathogenesis of pulmonary fibrosis remains unclear. We used single-cell RNA sequencing data to investigate the transcriptional profiles of immune cells in the lungs of 5 IPF patients and 3 subjects with non-fibrotic lungs. In an identifiable population of immune cells, we found increased percentage of CD8+ T cells in the T cell subpopulation in IPF. Monocle analyzed the dynamic immune status and cell transformation of CD8+ T cells, as well as the cytotoxicity and exhausted status of CD8+ T cell subpopulations at different stages. Among CD8+ T cells, we found differences in metabolic pathways in IPF and Ctrl, including lipid, amino acid and carbohydrate metabolic. By analyzing the metabolites of CD8+ T cells, we found that different populations of CD8+ T cells in IPF have unique metabolic characteristics, but they also have multiple identical up-regulated or down-regulated metabolites. In IPF, signaling pathways associated with fibrosis were enriched in CD8+ T cells, suggesting that CD8+ T cells may have an important contribution to fibrosis. Finally, we analyzed the interactions between CD8+ T cells and other cells. Together, these studies highlight key features of CD8+ T cells in the pathogenesis of IPF and help to develop effective therapeutic targets.
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Affiliation(s)
- Xuemei Wei
- Center of Respiratory and Critical Care Medicine, People's Hospital of Xinjiang Uygur Autonomous Region, Urumqi, Xinjiang 830001, China; State Key Laboratory of Pathogenesis, Prevention and Treatment of High Incidence Diseases in Central Asia, Clinical Laboratory Center, Tumor Hospital Affiliated to Xinjiang Medical University, Urumqi 830000, China
| | - Chengji Jin
- Department of Respiratory Medicine, The Second Affiliated Hospital, Hainan Medical University, Haikou 570100, China
| | - Dewei Li
- Center of Respiratory and Critical Care Medicine, People's Hospital of Xinjiang Uygur Autonomous Region, Urumqi, Xinjiang 830001, China
| | - Yujie Wang
- Department of Respiratory Medicine, The Second Affiliated Hospital, Hainan Medical University, Haikou 570100, China
| | - Shaomao Zheng
- Department of Respiratory Medicine, The Second Affiliated Hospital, Hainan Medical University, Haikou 570100, China
| | - Qiong Feng
- Department of Respiratory Medicine, The Second Affiliated Hospital, Hainan Medical University, Haikou 570100, China
| | - Ning Shi
- State Key Laboratory of Pathogenesis, Prevention and Treatment of High Incidence Diseases in Central Asia, Clinical Laboratory Center, Tumor Hospital Affiliated to Xinjiang Medical University, Urumqi 830000, China
| | - Weina Kong
- State Key Laboratory of Pathogenesis, Prevention and Treatment of High Incidence Diseases in Central Asia, Clinical Laboratory Center, Tumor Hospital Affiliated to Xinjiang Medical University, Urumqi 830000, China
| | - Xiumin Ma
- State Key Laboratory of Pathogenesis, Prevention and Treatment of High Incidence Diseases in Central Asia, Clinical Laboratory Center, Tumor Hospital Affiliated to Xinjiang Medical University, Urumqi 830000, China.
| | - Jing Wang
- Department of Respiratory Medicine, The Second Affiliated Hospital, Hainan Medical University, Haikou 570100, China; NHC Key Laboratory of Tropical Disease Control, Hainan Medical University, Haikou 571199, China.
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Salminen A. Inhibitory immune checkpoints suppress the surveillance of senescent cells promoting their accumulation with aging and in age-related diseases. Biogerontology 2024:10.1007/s10522-024-10114-w. [PMID: 38954358 DOI: 10.1007/s10522-024-10114-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2024] [Accepted: 06/18/2024] [Indexed: 07/04/2024]
Abstract
The accumulation of pro-inflammatory senescent cells within tissues is a common hallmark of the aging process and many age-related diseases. This modification has been called the senescence-associated secretory phenotype (SASP) and observed in cultured cells and in cells isolated from aged tissues. Currently, there is a debate whether the accumulation of senescent cells within tissues should be attributed to increased generation of senescent cells or to a defect in their elimination from aging tissues. Emerging studies have revealed that senescent cells display an increased expression of several inhibitory immune checkpoint ligands, especially those of the programmed cell death protein-1 (PD-1) ligand-1 (PD-L1) proteins. It is known that the PD-L1 ligands, especially those of cancer cells, target the PD-1 receptor of cytotoxic CD8+ T and natural killer (NK) cells disturbing their functions, e.g., evoking a decline in their cytotoxic activity and promoting their exhaustion and even apoptosis. An increase in the level of the PD-L1 protein in senescent cells was able to suppress their immune surveillance and inhibit their elimination by cytotoxic CD8+ T and NK cells. Senescent cells are known to express ligands for several inhibitory immune checkpoint receptors, i.e., PD-1, LILRB4, NKG2A, TIM-3, and SIRPα receptors. Here, I will briefly describe those pathways and examine whether these inhibitory checkpoints could be involved in the immune evasion of senescent cells with aging and age-related diseases. It seems plausible that an enhanced inhibitory checkpoint signaling can prevent the elimination of senescent cells from tissues and thus promote the aging process.
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Affiliation(s)
- Antero Salminen
- Department of Neurology, Institute of Clinical Medicine, University of Eastern Finland, P.O. Box 1627, 70211, Kuopio, Finland.
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3
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Salminen A. The role of the immunosuppressive PD-1/PD-L1 checkpoint pathway in the aging process and age-related diseases. J Mol Med (Berl) 2024; 102:733-750. [PMID: 38600305 PMCID: PMC11106179 DOI: 10.1007/s00109-024-02444-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 03/18/2024] [Accepted: 04/01/2024] [Indexed: 04/12/2024]
Abstract
The accumulation of senescent cells within tissues is a hallmark of the aging process. Senescent cells are also commonly present in many age-related diseases and in the cancer microenvironment. The escape of abnormal cells from immune surveillance indicates that there is some defect in the function of cytotoxic immune cells, e.g., CD8+ T cells and natural killer (NK) cells. Recent studies have revealed that the expression of programmed death-ligand 1 (PD-L1) protein is abundantly increased in senescent cells. An increase in the amount of PD-L1 protein protects senescent cells from clearance by the PD-1 checkpoint receptor in cytotoxic immune cells. In fact, the activation of the PD-1 receptor suppresses the cytotoxic properties of CD8+ T and NK cells, promoting a state of immunosenescence. The inhibitory PD-1/PD-L1 checkpoint pathway acts in cooperation with immunosuppressive cells; for example, activation of PD-1 receptor can enhance the differentiation of regulatory T cells (Treg), myeloid-derived suppressor cells (MDSC), and M2 macrophages, whereas the cytokines secreted by immunosuppressive cells stimulate the expression of the immunosuppressive PD-L1 protein. Interestingly, many signaling pathways known to promote cellular senescence and the aging process are crucial stimulators of the expression of PD-L1 protein, e.g., epigenetic regulation, inflammatory mediators, mTOR-related signaling, cGAS-STING pathway, and AhR signaling. It seems that the inhibitory PD-1/PD-L1 immune checkpoint axis has a crucial role in the accumulation of senescent cells and thus it promotes the aging process in tissues. Thus, the blockade of the PD-1/PD-L1 checkpoint signaling might be a potential anti-aging senolytic therapy. KEY MESSAGES: Senescent cells accumulate within tissues during aging and age-related diseases. Senescent cells are able to escape immune surveillance by cytotoxic immune cells. Expression of programmed death-ligand 1 (PD-L1) markedly increases in senescent cells. Age-related signaling stimulates the expression of PD-L1 protein in senescent cells. Inhibitory PD-1/PD-L1 checkpoint pathway suppresses clearance of senescent cells.
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Affiliation(s)
- Antero Salminen
- Department of Neurology, Institute of Clinical Medicine, University of Eastern Finland, P.O. Box 1627, FI-70211, Kuopio, Finland.
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Jiang A, Zheng X, Yan S, Yan J, Yao Y, He W. Advancing the Boundaries of Immunotherapy in Lung Adenocarcinoma with Idiopathic Pulmonary Fibrosis by a Biomimetic Proteinoid Enabling Selective Endocytosis. ACS NANO 2024. [PMID: 38319028 PMCID: PMC10883119 DOI: 10.1021/acsnano.3c09852] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2024]
Abstract
The coexistence of lung adenocarcinoma (LUAD) with idiopathic pulmonary fibrosis (IPF), which has been extensively documented as a prominent risk factor for checkpoint inhibitor-related pneumonitis (CIP) in patients undergoing immunotherapy, has long been considered a restricted domain for the use of immune checkpoint inhibitors (ICIs). To overcome it, an approach was employed herein to specifically target PD-L1 within the cellular interior, surpassing the conventional focus solely on the cytomembrane, thereby facilitating the development of ICIs capable of distinguishing between LUAD cells and noncancerous cells based on their distinctive endocytic propensities. By exploiting the aurophilicity-driven self-assembly of a PD-L1 binding peptide (PDBP) and subsequently encapsulating it within erythrocyte membranes (EM), the resulting biomimetic ICIs protein EMS-PDBP exhibited extraordinary selectivity in internalizing LUAD cells, effectively targeting PD-L1 within cancer cells while hindering its membrane translocation. The EMS-PDBP treatment not only reactivated the antitumor immune response in the LUAD orthotopic allograft mouse model but also demonstrated a favorable safety profile by effectively eliminating any immune-related adverse events (irAEs). Most significantly, EMS-PDBP successfully and safely restored the antitumor immune response in a mouse model of LUAD with coexistent IPF, thus shattering the confines of ICIs immunotherapy. The reported EMS-PDBP collectively offers a potential strategy for immune reactivation to overcome the limitations of immunotherapy in LUAD coexisting with IPF.
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Affiliation(s)
- Aimin Jiang
- Department of Medical Oncology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710061, China
| | - Xiaoqiang Zheng
- Department of Medical Oncology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710061, China
- Institute for Stem Cell & Regenerative Medicine, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710004, China
| | - Siqi Yan
- Institute for Stem Cell & Regenerative Medicine, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710004, China
| | - Jin Yan
- National & Local Joint Engineering Research Center of Biodiagnosis and Biotherapy, The Second Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710004, China
| | - Yu Yao
- Department of Medical Oncology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710061, China
| | - Wangxiao He
- Department of Medical Oncology, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an 710061, China
- Department of Talent Highland, The First Affiliated Hospital of Xi'an Jiao Tong University, Xi'an 710061, China
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Mutsaers SE, Miles T, Prêle CM, Hoyne GF. Emerging role of immune cells as drivers of pulmonary fibrosis. Pharmacol Ther 2023; 252:108562. [PMID: 37952904 DOI: 10.1016/j.pharmthera.2023.108562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 11/01/2023] [Accepted: 11/06/2023] [Indexed: 11/14/2023]
Abstract
The pathogenesis of pulmonary fibrosis, including idiopathic pulmonary fibrosis (IPF) and other forms of interstitial lung disease, involves a complex interplay of various factors including host genetics, environmental pollutants, infection, aberrant repair and dysregulated immune responses. Highly variable clinical outcomes of some ILDs, in particular IPF, have made it difficult to identify the precise mechanisms involved in disease pathogenesis and thus the development of a specific cure or treatment to halt and reverse the decline in patient health. With the advent of in-depth molecular diagnostics, it is becoming evident that the pathogenesis of IPF is unlikely to be the same for all patients and therefore will likely require different treatment approaches. Chronic inflammation is a cardinal feature of IPF and is driven by both innate and adaptive immune responses. Inflammatory cells and activated fibroblasts secrete various pro-inflammatory cytokines and chemokines that perpetuate the inflammatory response and contribute to the recruitment and activation of more immune cells and fibroblasts. The balance between pro-inflammatory and regulatory immune cell subsets, as well as the interactions between immune cell types and resident cells within the lung microenvironment, ultimately determines the extent of fibrosis and the potential for resolution. This review examines the role of the innate and adaptive immune responses in pulmonary fibrosis, with an emphasis on IPF. The role of different immune cell types is discussed as well as novel anti-inflammatory and immunotherapy approaches currently in clinical trial or in preclinical development.
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Affiliation(s)
- Steven E Mutsaers
- Institute for Respiratory Health, The University of Western Australia, Nedlands, WA, Australia.
| | - Tylah Miles
- Institute for Respiratory Health, The University of Western Australia, Nedlands, WA, Australia
| | - Cecilia M Prêle
- Institute for Respiratory Health, The University of Western Australia, Nedlands, WA, Australia; School of Medical, Molecular and Forensic Sciences, Murdoch University, WA, Australia
| | - Gerard F Hoyne
- Institute for Respiratory Health, The University of Western Australia, Nedlands, WA, Australia; The School of Health Sciences and Physiotherapy, University of Notre Dame Australia, Fremantle, WA, Australia
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Karampitsakos T, Galaris A, Chrysikos S, Papaioannou O, Vamvakaris I, Barbayianni I, Kanellopoulou P, Grammenoudi S, Anagnostopoulos N, Stratakos G, Katsaras M, Sampsonas F, Dimakou K, Manali ED, Papiris S, Tourki B, Juan-Guardela BM, Bakakos P, Bouros D, Herazo-Maya JD, Aidinis V, Tzouvelekis A. Expression of PD-1/PD-L1 axis in mediastinal lymph nodes and lung tissue of human and experimental lung fibrosis indicates a potential therapeutic target for idiopathic pulmonary fibrosis. Respir Res 2023; 24:279. [PMID: 37964265 PMCID: PMC10648728 DOI: 10.1186/s12931-023-02551-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 10/02/2023] [Indexed: 11/16/2023] Open
Abstract
BACKGROUND Mediastinal lymph node enlargement is prevalent in patients with idiopathic pulmonary fibrosis (IPF). Studies investigating whether this phenomenon reflects specific immunologic activation are lacking. METHODS Programmed cell death-1 (PD-1)/ programmed cell death ligand-1 (PD-L1) expression in mediastinal lymph nodes and lung tissues was analyzed. PD-1, PD-L1 mRNA expression was measured in tracheobronchial lymph nodes of mice following bleomycin-induced injury on day 14. Finally, the effect of the PD-1 inhibitor, pembrolizumab, in bleomycin-induced pulmonary fibrosis was investigated. RESULTS We analyzed mediastinal lymph nodes of thirty-three patients (n = 33, IPF: n = 14, lung cancer: n = 10, concomitant IPF and lung cancer: n = 9) and lung tissues of two hundred nineteen patients (n = 219, IPF: 123, controls: 96). PD-1 expression was increased, while PD-L1 expression was decreased, in mediastinal lymph nodes of patients with IPF compared to lung cancer and in IPF lungs compared to control lungs. Tracheobronchial lymph nodes isolated on day 14 from bleomycin-treated mice exhibited increased size and higher PD-1, PD-L1 mRNA levels compared to saline-treated animals. Pembrolizumab blunted bleomycin-induced lung fibrosis, as indicated by reduction in Ashcroft score and improvement in respiratory mechanics. CONCLUSIONS Mediastinal lymph nodes of patients with IPF exhibit differential expression profiles than those of patients with lung cancer indicating distinct immune-mediated pathways regulating fibrogenesis and carcinogenesis. PD-1 expression in mediastinal lymph nodes is in line with lung tissue expression. Lower doses of pembrolizumab might exert antifibrotic effects. Clinical trials aiming to endotype patients based on mediastinal lymph node profiling and accordingly implement targeted therapies such as PD-1 inhibitors are greatly anticipated.
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Affiliation(s)
- Theodoros Karampitsakos
- Department of Respiratory Medicine, University Hospital of Patras, Rio, Greece
- Ubben Center and Laboratory for Pulmonary Fibrosis Research, Morsani College of Medicine, University of South Florida, 33620, Tampa, FL, USA
| | - Apostolos Galaris
- Institute of Bio- Innovation, Biomedical Sciences Research Center Alexander Fleming, Athens, Greece
| | - Serafeim Chrysikos
- 5th Department of Pneumonology, Hospital for Thoracic Diseases, "SOTIRIA", Athens, Greece
| | - Ourania Papaioannou
- Department of Respiratory Medicine, University Hospital of Patras, Rio, Greece
| | - Ioannis Vamvakaris
- Department of Pathology, Hospital for Thoracic Diseases, "SOTIRIA", Athens, Greece
| | - Ilianna Barbayianni
- Institute of Bio- Innovation, Biomedical Sciences Research Center Alexander Fleming, Athens, Greece
| | - Paraskevi Kanellopoulou
- Institute of Bio- Innovation, Biomedical Sciences Research Center Alexander Fleming, Athens, Greece
| | - Sofia Grammenoudi
- Institute of Bio- Innovation, Biomedical Sciences Research Center Alexander Fleming, Athens, Greece
| | - Nektarios Anagnostopoulos
- First Academic Department of Pneumonology, "SOTIRIA", Medical School, Hospital for Thoracic Diseases, National and Kapodistrian University of Athens, Athens, Greece
| | - Grigoris Stratakos
- First Academic Department of Pneumonology, "SOTIRIA", Medical School, Hospital for Thoracic Diseases, National and Kapodistrian University of Athens, Athens, Greece
| | - Matthaios Katsaras
- Department of Respiratory Medicine, University Hospital of Patras, Rio, Greece
| | - Fotios Sampsonas
- Department of Respiratory Medicine, University Hospital of Patras, Rio, Greece
| | - Katerina Dimakou
- 5th Department of Pneumonology, Hospital for Thoracic Diseases, "SOTIRIA", Athens, Greece
| | - Effrosyni D Manali
- 2nd Pulmonary Medicine Department, Athens Medical School, "ATTIKON" University Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Spyridon Papiris
- 2nd Pulmonary Medicine Department, Athens Medical School, "ATTIKON" University Hospital, National and Kapodistrian University of Athens, Athens, Greece
| | - Bochra Tourki
- Ubben Center and Laboratory for Pulmonary Fibrosis Research, Morsani College of Medicine, University of South Florida, 33620, Tampa, FL, USA
| | - Brenda M Juan-Guardela
- Ubben Center and Laboratory for Pulmonary Fibrosis Research, Morsani College of Medicine, University of South Florida, 33620, Tampa, FL, USA
| | - Petros Bakakos
- First Academic Department of Pneumonology, "SOTIRIA", Medical School, Hospital for Thoracic Diseases, National and Kapodistrian University of Athens, Athens, Greece
| | - Demosthenes Bouros
- First Academic Department of Pneumonology, "SOTIRIA", Medical School, Hospital for Thoracic Diseases, National and Kapodistrian University of Athens, Athens, Greece
| | - Jose D Herazo-Maya
- Ubben Center and Laboratory for Pulmonary Fibrosis Research, Morsani College of Medicine, University of South Florida, 33620, Tampa, FL, USA
| | - Vassilis Aidinis
- Institute of Bio- Innovation, Biomedical Sciences Research Center Alexander Fleming, Athens, Greece
| | - Argyris Tzouvelekis
- Department of Respiratory Medicine, University Hospital of Patras, Rio, Greece.
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Zhang YC, Zhang YT, Wang Y, Zhao Y, He LJ. What role does PDL1 play in EMT changes in tumors and fibrosis? Front Immunol 2023; 14:1226038. [PMID: 37649487 PMCID: PMC10463740 DOI: 10.3389/fimmu.2023.1226038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2023] [Accepted: 07/28/2023] [Indexed: 09/01/2023] Open
Abstract
Epithelial-mesenchymal transformation (EMT) plays a pivotal role in embryonic development, tissue fibrosis, repair, and tumor invasiveness. Emerging studies have highlighted the close association between EMT and immune checkpoint molecules, particularly programmed cell death ligand 1 (PDL1). PDL1 exerts its influence on EMT through bidirectional regulation. EMT-associated factors, such as YB1, enhance PDL1 expression by directly binding to its promoter. Conversely, PDL1 signaling triggers downstream pathways like PI3K/AKT and MAPK, promoting EMT and facilitating cancer cell migration and invasion. Targeting PDL1 holds promise as a therapeutic strategy for EMT-related diseases, including cancer and fibrosis. Indeed, PDL1 inhibitors, such as pembrolizumab and nivolumab, have shown promising results in clinical trials for various cancers. Recent research has also indicated their potential benefit in fibrosis treatment in reducing fibroblast activation and extracellular matrix deposition, thereby addressing fibrosis. In this review, we examine the multifaceted role of PDL1 in immunomodulation, growth, and fibrosis promotion. We discuss the challenges, mechanisms, and clinical observations related to PDL1, including the limitations of the PD1/PDL1 axis in treatment and PD1-independent intrinsic PDL1 signaling. Our study highlights the dynamic changes in PDL1 expression during the EMT process across various tumor types. Through interplay between PDL1 and EMT, we uncover co-directional alterations, regulatory pathways, and diverse changes resulting from PDL1 intervention in oncology. Additionally, our findings emphasize the dual role of PDL1 in promoting fibrosis and modulating immune responses across multiple diseases, with potential implications for therapeutic approaches. We particularly investigate the therapeutic potential of targeting PDL1 in type II EMT fibrosis: strike balance between fibrosis modulation and immune response regulation. This analysis provides valuable insights into the multifaceted functions of PDL1 and contributes to our understanding of its complex mechanisms and therapeutic implications.
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Affiliation(s)
- Yun-Chao Zhang
- Department of Nephrology, Xi Jing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Yu-Ting Zhang
- Department of Nephrology, Xi Jing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Yi Wang
- Department of Nephrology, Xi Jing Hospital, The Fourth Military Medical University, Xi'an, China
| | - Ya Zhao
- Department of Medical Microbiology and Parasitology, Fourth Military Medical University, Xi'an, China
| | - Li-Jie He
- Department of Nephrology, Xi Jing Hospital, The Fourth Military Medical University, Xi'an, China
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Zhao Y, Qu Y, Hao C, Yao W. PD-1/PD-L1 axis in organ fibrosis. Front Immunol 2023; 14:1145682. [PMID: 37275876 PMCID: PMC10235450 DOI: 10.3389/fimmu.2023.1145682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 05/09/2023] [Indexed: 06/07/2023] Open
Abstract
Fibrosis is a pathological tissue repair activity in which many myofibroblasts are activated and extracellular matrix are excessively accumulated, leading to the formation of permanent scars and finally organ failure. A variety of organs, including the lung, liver, kidney, heart, and skin, can undergo fibrosis under the stimulation of various exogenous or endogenous pathogenic factors. At present, the pathogenesis of fibrosis is still not fully elucidated, but it is known that the immune system plays a key role in the initiation and progression of fibrosis. Immune checkpoint molecules are key regulators to maintain immune tolerance and homeostasis, among which the programmed cell death protein 1/programmed death ligand 1 (PD-1/PD-L1) axis has attracted much attention. The exciting achievements of tumor immunotherapy targeting PD-1/PD-L1 provide new insights into its use as a therapeutic target for other diseases. In recent years, the role of PD-1/PD-L1 axis in fibrosis has been preliminarily explored, further confirming the close relationship among PD-1/PD-L1 signaling, immune regulation, and fibrosis. This review discusses the structure, expression, function, and regulatory mechanism of PD-1 and PD-L1, and summarizes the research progress of PD-1/PD-L1 signaling in fibrotic diseases.
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Affiliation(s)
| | | | | | - Wu Yao
- *Correspondence: Wu Yao, ; Changfu Hao,
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