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Dimayuga PC, Chyu KY, Zhao X, Zhou J, Lio NWM, Chernomordik F, Berman D, Shah PK, Cercek B. A Novel Pathway of Platelet Activation in ACS Mediated by LL-37 Immunoglobulin G Autoantibody Immune Complexes. JACC Basic Transl Sci 2024; 9:877-887. [PMID: 39170950 PMCID: PMC11334414 DOI: 10.1016/j.jacbts.2024.04.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Revised: 04/05/2024] [Accepted: 04/23/2024] [Indexed: 08/23/2024]
Abstract
The cathelicidin antimicrobial peptide LL-37 is a self-antigen in neutrophil extracellular traps that provokes autoantibody responses in autoimmune/autoinflammatory conditions. LL-37 immunoglobulin (Ig) G autoantibody levels were measured in subjects with and without atherosclerotic cardiovascular disease assessed using the coronary artery calcium score, in patients who had a future myocardial infarction and in a cohort of acute coronary syndrome (ACS) patients. LL-37 IgG levels were not associated with coronary artery calcium score, but future myocardial infarction patients had significantly higher LL-37 IgG at baseline. Reduced LL-37 IgG in ACS was associated with increased LL-37 IgG-immune complex. ACS plasma increased activated CD62P+ platelets from healthy donors mediated in part by LL-37 IgG-immune complexes and platelet Fc gamma receptor 2a.
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Affiliation(s)
- Paul C. Dimayuga
- Oppenheimer Atherosclerosis Research Center, Department of Cardiology, Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Kuang-Yuh Chyu
- Oppenheimer Atherosclerosis Research Center, Department of Cardiology, Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Xiaoning Zhao
- Oppenheimer Atherosclerosis Research Center, Department of Cardiology, Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Jianchang Zhou
- Oppenheimer Atherosclerosis Research Center, Department of Cardiology, Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Nicole Wai Man Lio
- Oppenheimer Atherosclerosis Research Center, Department of Cardiology, Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Fernando Chernomordik
- Oppenheimer Atherosclerosis Research Center, Department of Cardiology, Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Daniel Berman
- Departments of Imaging and Medicine and Burns and Allen Research Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Prediman K. Shah
- Oppenheimer Atherosclerosis Research Center, Department of Cardiology, Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Bojan Cercek
- Oppenheimer Atherosclerosis Research Center, Department of Cardiology, Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, California, USA
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Raposo B, Klareskog L, Robinson WH, Malmström V, Grönwall C. The peculiar features, diversity and impact of citrulline-reactive autoantibodies. Nat Rev Rheumatol 2024; 20:399-416. [PMID: 38858604 DOI: 10.1038/s41584-024-01124-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/10/2024] [Indexed: 06/12/2024]
Abstract
Since entering the stage 25 years ago as a highly specific serological biomarker for rheumatoid arthritis, anti-citrullinated protein antibodies (ACPAs) have been a topic of extensive research. This hallmark B cell response arises years before disease onset, displays interpatient autoantigen variability, and is associated with poor clinical outcomes. Technological and scientific advances have revealed broad clonal diversity and intriguing features including high levels of somatic hypermutation, variable-domain N-linked glycosylation, hapten-like peptide interactions, and clone-specific multireactivity to citrullinated, carbamylated and acetylated epitopes. ACPAs have been found in different isotypes and subclasses, in both circulation and tissue, and are secreted by both plasmablasts and long-lived plasma cells. Notably, although some disease-promoting features have been reported, results now demonstrate that certain monoclonal ACPAs therapeutically block arthritis and inflammation in mouse models. A wealth of functional studies using patient-derived polyclonal and monoclonal antibodies have provided evidence for pathogenic and protective effects of ACPAs in the context of arthritis. To understand the roles of ACPAs, one needs to consider their immunological properties by incorporating different facets such as rheumatoid arthritis B cell biology, environmental triggers and chronic antigen exposure. The emerging picture points to a complex role of citrulline-reactive autoantibodies, in which the diversity and dynamics of antibody clones could determine clinical progression and manifestations.
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Affiliation(s)
- Bruno Raposo
- Department of Medicine, Division of Rheumatology, Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
| | - Lars Klareskog
- Department of Medicine, Division of Rheumatology, Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
| | - William H Robinson
- Division of Immunology and Rheumatology, Department of Medicine, Stanford University School of Medicine, Stanford, CA, USA
- VA Palo Alto Health Care System, Palo Alto, CA, USA
| | - Vivianne Malmström
- Department of Medicine, Division of Rheumatology, Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
| | - Caroline Grönwall
- Department of Medicine, Division of Rheumatology, Center for Molecular Medicine, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
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Chen Y, Teng Y, Xu P, Wang S. The Role of Citrullination Modification in CD4 + T Cells in the Pathogenesis of Immune-Related Diseases. Biomolecules 2024; 14:400. [PMID: 38672418 PMCID: PMC11047979 DOI: 10.3390/biom14040400] [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: 02/13/2024] [Revised: 03/21/2024] [Accepted: 03/22/2024] [Indexed: 04/28/2024] Open
Abstract
The post-translational modifications (PTMs) of proteins play a crucial role in increasing the functional diversity of proteins and are associated with the pathogenesis of various diseases. This review focuses on a less explored PTM called citrullination, which involves the conversion of arginine to citrulline. This process is catalyzed by peptidyl arginine deiminases (PADs). Different members of the PAD family have distinct tissue distribution patterns and functions. Citrullination is a post-translational modification of native proteins that can alter their structure and convert them into autoantigens; thus, it mediates the occurrence of autoimmune diseases. CD4+ T cells, including Th1, Th2, and Th17 cells, are important immune cells involved in mediating autoimmune diseases, allergic reactions, and tumor immunity. PADs can induce citrullination in CD4+ T cells, suggesting a role for citrullination in CD4+ T cell subset differentiation and function. Understanding the role of citrullination in CD4+ T cells may provide insights into immune-related diseases and inflammatory processes.
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Affiliation(s)
- Yuhang Chen
- Department of Laboratory Medicine, Affiliated Hospital of Jiangsu University, Zhenjiang 212001, China;
- Jiangsu Key Laboratory of Laboratory Medicine, Department of Immunology, School of Medicine, Jiangsu University, Zhenjiang 212013, China
| | - Yi Teng
- Jiangsu Key Laboratory of Laboratory Medicine, Department of Immunology, School of Medicine, Jiangsu University, Zhenjiang 212013, China
| | - Ping Xu
- Department of Laboratory Medicine, The Fifth People’s Hospital of Suzhou, Suzhou 215505, China
| | - Shengjun Wang
- Department of Laboratory Medicine, Affiliated Hospital of Jiangsu University, Zhenjiang 212001, China;
- Jiangsu Key Laboratory of Laboratory Medicine, Department of Immunology, School of Medicine, Jiangsu University, Zhenjiang 212013, China
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Lobognon VD, Alard JE. Could AMPs and B-cells be the missing link in understanding periodontitis? Front Immunol 2022; 13:887147. [PMID: 36211356 PMCID: PMC9532695 DOI: 10.3389/fimmu.2022.887147] [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: 03/02/2022] [Accepted: 08/01/2022] [Indexed: 12/29/2022] Open
Abstract
Periodontal diseases are common inflammatory conditions characterized by bone loss in response to simultaneous bacterial aggression and host defenses. The etiology of such diseases is still not completely understood, however. It has been shown that specific pathogens involved in the build-up of dysbiotic biofilms participate actively in the establishment of periodontitis. This multifactorial pathology also depends on environmental factors and host characteristics, especially defenses. The immune response to the pathogens seems to be critical in preventing the disease from starting but also contributes to tissue damage. It is known that small molecules known as antimicrobial peptides (AMPs) are key actors in the innate immune response. They not only target microbes, but also act as immuno-modulators. They can help to recruit or activate cells such as neutrophils, monocytes, dendritic cells, or lymphocytes. AMPs have already been described in the periodontium, and their expression seems to be connected to disease activity. Alpha and beta defensins and LL37 are the AMPs most frequently linked to periodontitis. Additionally, leukocyte infiltrates, especially B-cells, have also been linked to the severity of periodontitis. Indeed, the particular subpopulations of B-cells in these infiltrates have been linked to inflammation and bone resorption. A link between B-cells and AMP could be relevant to understanding B-cells' action. Some AMP receptors, such as chemokines receptors, toll-like receptors, or purinergic receptors, have been shown to be expressed by B-cells. Consequently, the action of AMPs on B-cell subpopulations could participate to B-cell recruitment, their differentiation, and their implication in both periodontal defense and destruction.
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Affiliation(s)
- Vanessa Dominique Lobognon
- B lymphocytes, Autoimmunity and Immunotherapies (LBAI), Mixed Research Unit (UMR)1227 INSERM, University of Brest, Brest, France
| | - Jean-Eric Alard
- B lymphocytes, Autoimmunity and Immunotherapies (LBAI), Mixed Research Unit (UMR)1227 INSERM, University of Brest, Brest, France,Service d’Odontologie, University Hospital (CHU) de Brest, Brest, France,*Correspondence: Jean-Eric Alard,
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LL-37, a Multi-Faceted Amphipathic Peptide Involved in NETosis. Cells 2022; 11:cells11152463. [PMID: 35954305 PMCID: PMC9368159 DOI: 10.3390/cells11152463] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Accepted: 08/01/2022] [Indexed: 12/14/2022] Open
Abstract
Innate immunity responds to infections and inflammatory stimuli through a carefully choreographed set of interactions between cells, stimuli and their specific receptors. Of particular importance are endogenous peptides, which assume roles as defensins or alarmins, growth factors or wound repair inducers. LL-37, a proteolytic fragment of cathelicidin, fulfills the roles of a defensin by inserting into the membranes of bacterial pathogens, functions as alarmin in stimulating chemotaxis of innate immune cells, and alters the structure and efficacy of various cytokines. Here, we draw attention to the direct effect of LL-37 on neutrophils and the release of extracellular traps (NETs), as NETs have been established as mediators of immune defense against pathogens but also as important contributors to chronic disease and tissue pathogenesis. We propose a specific structural basis for LL-37 function, in part by highlighting the structural flexibility of LL-37 and its ability to adapt to distinct microenvironments and interacting counterparts.
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Yang L, Yan Y. Emerging Roles of Post-Translational Modifications in Skin Diseases: Current Knowledge, Challenges and Future Perspectives. J Inflamm Res 2022; 15:965-975. [PMID: 35177923 PMCID: PMC8846607 DOI: 10.2147/jir.s339296] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Accepted: 11/12/2021] [Indexed: 12/24/2022] Open
Abstract
Post-translational modifications (PTMs) of proteins represent as a key step in regulating their biological functions and dynamic interaction with other players. This process is fine-tuned by a myriad of enzymes named “writers, readers and erasers” whose actions are precisely controlled. Either the mutation, aberration in the expression of the aforementioned enzymes or their substrates have shown to participate in the pathogenesis of various skin diseases such as melanoma, vitiligo, psoriasis, eczema, atopic dermatitis and inherited dermatological diseases. It is becoming increasingly clear that key transcriptional factors, inflammation-related molecules are prone to PTMs. Despite their importance in regulating key processes including inflammation, keratinocyte apoptosis, proliferation and differentiation, PTMs have received less attention due to the challenges involved. Here in this review we summarize the role of the most common types and the newly discovered PTMs, including acetylation, glycosylation, citrullination, PARylation and sumoylation in dermatoses and surveys the recent progress in PTM-based therapeutic approaches in skin diseases.
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Affiliation(s)
- Luting Yang
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi’an, People’s Republic of China
- Correspondence: Luting Yang; Yaping Yan, Email ;
| | - Yaping Yan
- Key Laboratory of the Ministry of Education for Medicinal Resources and Natural Pharmaceutical Chemistry, National Engineering Laboratory for Resource Development of Endangered Crude Drugs in Northwest of China, College of Life Sciences, Shaanxi Normal University, Xi’an, People’s Republic of China
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Complementary Effects of Carbamylated and Citrullinated LL37 in Autoimmunity and Inflammation in Systemic Lupus Erythematosus. Int J Mol Sci 2021; 22:ijms22041650. [PMID: 33562078 PMCID: PMC7915858 DOI: 10.3390/ijms22041650] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 01/27/2021] [Accepted: 02/02/2021] [Indexed: 01/10/2023] Open
Abstract
LL37 acts as T-cell/B-cell autoantigen in Systemic lupus erythematosus (SLE) and psoriatic disease. Moreover, when bound to "self" nucleic acids, LL37 acts as "danger signal," leading to type I interferon (IFN-I)/pro-inflammatory factors production. T-cell epitopes derived from citrullinated-LL37 act as better antigens than unmodified LL37 epitopes in SLE, at least in selected HLA-backgrounds, included the SLE-associated HLA-DRB1*1501/HLA-DRB5*0101 backgrounds. Remarkably, while "fully-citrullinated" LL37 acts as better T-cell-stimulator, it loses DNA-binding ability and the associated "adjuvant-like" properties. Since LL37 undergoes a further irreversible post-translational modification, carbamylation and antibodies to carbamylated self-proteins other than LL37 are present in SLE, here we addressed the involvement of carbamylated-LL37 in autoimmunity and inflammation in SLE. We detected carbamylated-LL37 in SLE-affected tissues. Most importantly, carbamylated-LL37-specific antibodies and CD4 T-cells circulate in SLE and both correlate with disease activity. In contrast to "fully citrullinated-LL37," "fully carbamylated-LL37" maintains both innate and adaptive immune-cells' stimulatory abilities: in complex with DNA, carbamylated-LL37 stimulates plasmacytoid dendritic cell IFN-α production and B-cell maturation into plasma cells. Thus, we report a further example of how different post-translational modifications of a self-antigen exert complementary effects that sustain autoimmunity and inflammation, respectively. These data also show that T/B-cell responses to carbamylated-LL37 represent novel SLE disease biomarkers.
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Citrullination-Resistant LL-37 Is a Potent Antimicrobial Agent in the Inflammatory Environment High in Arginine Deiminase Activity. Int J Mol Sci 2020; 21:ijms21239126. [PMID: 33266231 PMCID: PMC7730452 DOI: 10.3390/ijms21239126] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 11/26/2020] [Accepted: 11/27/2020] [Indexed: 12/13/2022] Open
Abstract
LL-37, the only member of the mammalian cathelicidin in humans, plays an essential role in innate immunity by killing pathogens and regulating the inflammatory response. However, at an inflammatory focus, arginine residues in LL-37 can be converted to citrulline via a reaction catalyzed by peptidyl-arginine deiminases (PAD2 and PAD4), which are expressed in neutrophils and are highly active during the formation of neutrophil extracellular traps (NETs). Citrullination impairs the bactericidal activity of LL-37 and abrogates its immunomodulatory functions. Therefore, we hypothesized that citrullination-resistant LL-37 variants would retain the functionality of the native peptide in the presence of PADs. To test this hypothesis, we synthetized LL-37 in which arginine residues were substituted by homoarginine (hArg-LL-37). Bactericidal activity of hArg-LL-37 was comparable with that of native LL-37, but neither treatment with PAD4 nor exposure to NETs affected the antibacterial and immunomodulatory activities of hArg-LL-37. Importantly, the susceptibilities of LL-37 and hArg-LL-37 to degradation by proteases did not significantly differ. Collectively, we demonstrated that citrullination-resistant hArg-LL-37 is an attractive lead compound for the generation of new agents to treat bacterial infections and other inflammatory diseases associated with enhanced PAD activity. Moreover, our results provide a proof-of-concept for synthesis of therapeutic peptides using homoarginine.
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