1
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Li Y, Ruth JH, Rasmussen SM, Athukorala KS, Weber DP, Amin MA, Campbell PL, Singer NG, Fox DA, Lin F. Attenuation of Murine Collagen-Induced Arthritis by Targeting CD6. Arthritis Rheumatol 2020; 72:1505-1513. [PMID: 32307907 DOI: 10.1002/art.41288] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 04/09/2020] [Indexed: 12/18/2022]
Abstract
OBJECTIVE CD6 is an important regulator of T cell function that interacts with the ligands CD166 and CD318. To further clarify the significance of CD6 in rheumatoid arthritis (RA), we examined the effects of targeting CD6 in the mouse model of collagen-induced arthritis (CIA), using CD6-knockout (CD6-KO) mice and CD6-humanized mice that express human CD6 in lieu of mouse CD6 on their T cells. METHODS We immunized wild-type (WT) and CD6 gene-KO mice with a collagen emulsion to induce CIA. For treatment studies using CD6-humanized mice, mice were immunized similarly and a mouse anti-human CD6 IgG (UMCD6) or control IgG was injected on days 7, 14, and 21. Joint tissues were evaluated for tissue damage, leukocyte infiltration, and local inflammatory cytokine production. Collagen-specific Th1, Th9, and Th17 responses and serum levels of collagen-specific IgG subclasses were also evaluated in WT and CD6-KO mice with CIA. RESULTS The absence of CD6 reduced 1) collagen-specific Th9 and Th17, but not Th1 responses, 2) the levels of many proinflammatory joint cytokines, and 3) serum levels of collagen-reactive total IgG and IgG1, but not IgG2a and IgG3. Joint homogenate hemoglobin content was significantly reduced in CD6-KO mice with CIA compared to WT mice with CIA (P < 0.05) (reduced angiogenesis). Moreover, treating CD6-humanized mice with mouse anti-human CD6 monoclonal antibody was similarly effective in reducing joint inflammation in CIA. CONCLUSION Taken together, these data suggest that interaction of CD6 with its ligands is important for the perpetuation of CIA and other inflammatory arthritides that are T cell driven.
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Affiliation(s)
- Yan Li
- Cleveland Clinic, Cleveland, Ohio
| | | | | | | | | | | | | | | | | | - Feng Lin
- Cleveland Clinic, Cleveland, Ohio
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2
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Gonçalves CM, Henriques SN, Santos RF, Carmo AM. CD6, a Rheostat-Type Signalosome That Tunes T Cell Activation. Front Immunol 2018; 9:2994. [PMID: 30619347 PMCID: PMC6305463 DOI: 10.3389/fimmu.2018.02994] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 12/04/2018] [Indexed: 12/14/2022] Open
Abstract
Following T cell receptor triggering, T cell activation is initiated and amplified by the assembly at the TCR/CD3 macrocomplex of a multitude of stimulatory enzymes that activate several signaling cascades. The potency of signaling is, however, modulated by various inhibitory components already at the onset of activation, long before co-inhibitory immune checkpoints are expressed to help terminating the response. CD5 and CD6 are surface glycoproteins of T cells that have determinant roles in thymocyte development, T cell activation and immune responses. They belong to the superfamily of scavenger receptor cysteine-rich (SRCR) glycoproteins but whereas the inhibitory role of CD5 has been established for long, there is still controversy on whether CD6 may have similar or antagonistic functions on T cell signaling. Analysis of the structure and molecular associations of CD5 and CD6 indicates that these molecules assemble at the cytoplasmic tail a considerable number of signaling effectors that can putatively transduce diverse types of intracellular signals. Biochemical studies have concluded that both receptors can antagonize the flow of TCR-mediated signaling; however, the impact that CD5 and CD6 have on T cell development and T cell-mediated immune responses may be different. Here we analyze the signaling function of CD6, the common and also the different properties it exhibits comparing with CD5, and interpret the functional effects displayed by CD6 in recent animal models.
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Affiliation(s)
- Carine M Gonçalves
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,Instituto de Biologia Molecular e Celular, Porto, Portugal
| | - Sónia N Henriques
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,Instituto de Biologia Molecular e Celular, Porto, Portugal.,Instituto de Ciências Biomédicas Abel Salazar and Faculdade de Ciências, Universidade do Porto, Porto, Portugal
| | - Rita F Santos
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,Instituto de Biologia Molecular e Celular, Porto, Portugal.,Instituto de Ciências Biomédicas Abel Salazar and Faculdade de Ciências, Universidade do Porto, Porto, Portugal
| | - Alexandre M Carmo
- Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.,Instituto de Biologia Molecular e Celular, Porto, Portugal
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3
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Consuegra-Fernández M, Lin F, Fox DA, Lozano F. Clinical and experimental evidence for targeting CD6 in immune-based disorders. Autoimmun Rev 2018. [DOI: 10.1016/j.autrev.2017.12.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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4
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The role of CD6 in autoimmune diseases. Cell Mol Immunol 2018; 15:1001-1002. [PMID: 29572546 DOI: 10.1038/s41423-018-0015-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2018] [Accepted: 02/07/2018] [Indexed: 11/08/2022] Open
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5
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Consuegra-Fernández M, Isamat M, Lozano F. Commentary: CD6 As a Potential Target for Treating Multiple Sclerosis. Front Immunol 2017; 8:1217. [PMID: 29033937 PMCID: PMC5626862 DOI: 10.3389/fimmu.2017.01217] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2017] [Accepted: 09/14/2017] [Indexed: 01/07/2023] Open
Affiliation(s)
- Marta Consuegra-Fernández
- Immunoreceptors of the Innate and Adaptive System, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain
| | - Marcos Isamat
- Immunoreceptors of the Innate and Adaptive System, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain
| | - Francisco Lozano
- Immunoreceptors of the Innate and Adaptive System, Institut d'Investigacions Biomèdiques August Pi i Sunyer, Barcelona, Spain.,Servei d'Immunologia, Centre de Diagnòstic Biomèdic, Hospital Clínic de Barcelona, Barcelona, Spain.,Departament de Biomedicina, Universitat de Barcelona, Barcelona, Spain
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6
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Willrodt AH, Beffinger M, Vranova M, Protsyuk D, Schuler K, Jadhav M, Heikenwalder M, van den Broek M, Borsig L, Halin C. Stromal Expression of Activated Leukocyte Cell Adhesion Molecule Promotes Lung Tumor Growth and Metastasis. THE AMERICAN JOURNAL OF PATHOLOGY 2017; 187:2558-2569. [PMID: 28822802 DOI: 10.1016/j.ajpath.2017.07.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Revised: 06/28/2017] [Accepted: 07/26/2017] [Indexed: 01/07/2023]
Abstract
Activated leukocyte cell adhesion molecule (ALCAM) is expressed on various cell types, including leukocytes, endothelial cells, and certain tumor cells. Although ALCAM expression on tumor cells has been linked to tumor invasion and metastatic spread, the contribution of ALCAM expressed in cells forming the tumor stroma to cancer progression has not been investigated. In this study, ALCAM-deficient (ALCAM-/-) mice were used to evaluate the role of ALCAM in lung tumor growth and metastasis. ALCAM-/- mice displayed an altered blood vascular network in the lung and the diaphragm, indicative of an angiogenetic defect. The absence of ALCAM expression in cells forming the stromal tumor microenvironment profoundly affected lung tumor growth in three different i.v. metastasis models. In the case of Lewis lung carcinoma (LLC), an additional defect in tumor cell homing to the lungs and a resulting reduction in the number of lung tumor nodules were observed. Similarly, when LLC cells were implanted subcutaneously for the study of spontaneous tumor cell metastasis, the rate of LLC metastasis to the lungs was profoundly reduced in ALCAM-/- mice. Taken together, our work demonstrates for the first time the in vivo contribution of ALCAM to angiogenesis and reveals a novel role of stromally expressed ALCAM in supporting tumor growth and metastatic spread.
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Affiliation(s)
- Ann-Helen Willrodt
- Institute of Pharmaceutical Sciences, ETH Zurich (Swiss Federal Institute of Technology), Zurich, Switzerland
| | - Michal Beffinger
- Institute of Experimental Immunology, University of Zurich, Zurich, Switzerland
| | - Martina Vranova
- Institute of Pharmaceutical Sciences, ETH Zurich (Swiss Federal Institute of Technology), Zurich, Switzerland
| | - Darya Protsyuk
- Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Katja Schuler
- Institute of Pharmaceutical Sciences, ETH Zurich (Swiss Federal Institute of Technology), Zurich, Switzerland
| | - Maria Jadhav
- Institute of Pharmaceutical Sciences, ETH Zurich (Swiss Federal Institute of Technology), Zurich, Switzerland
| | - Mathias Heikenwalder
- Division of Chronic Inflammation and Cancer, German Cancer Research Center, Heidelberg, Germany
| | | | - Lubor Borsig
- Institute of Physiology, University of Zurich, Zurich, Switzerland
| | - Cornelia Halin
- Institute of Pharmaceutical Sciences, ETH Zurich (Swiss Federal Institute of Technology), Zurich, Switzerland.
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7
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Abstract
It has been proposed that CD6, an important regulator of T cells, functions by interacting with its currently identified ligand, CD166, but studies performed during the treatment of autoimmune conditions suggest that the CD6-CD166 interaction might not account for important functions of CD6 in autoimmune diseases. The antigen recognized by mAb 3A11 has been proposed as a new CD6 ligand distinct from CD166, yet the identity of it is hitherto unknown. We have identified this CD6 ligand as CD318, a cell surface protein previously found to be present on various epithelial cells and many tumor cells. We found that, like CD6 knockout (KO) mice, CD318 KO mice are also protected in experimental autoimmune encephalomyelitis. In humans, we found that CD318 is highly expressed in synovial tissues and participates in CD6-dependent adhesion of T cells to synovial fibroblasts. In addition, soluble CD318 is chemoattractive to T cells and levels of soluble CD318 are selectively and significantly elevated in the synovial fluid from patients with rheumatoid arthritis and juvenile inflammatory arthritis. These results establish CD318 as a ligand of CD6 and a potential target for the diagnosis and treatment of autoimmune diseases such as multiple sclerosis and inflammatory arthritis.
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8
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Abstract
CD6 was established as a marker of T cells more than three decades ago, and recent studies have identified CD6 as a risk gene for multiple sclerosis (MS), a disease in which autoreactive T cells are integrally involved. Nevertheless, the precise role of CD6 in regulating T-cell responses is controversial and its significance in the pathogenesis of various diseases remains elusive, partly due to the lack of animals engineered to alter expression of the CD6 gene. In this report, we found that CD6 KO mice showed decreased pathogenic T-cell responses, reduced spinal cord T-cell infiltration, and attenuated disease severity in experimental autoimmune encephalomyelitis (EAE), an animal model of MS. CD6-deficient T cells exhibited augmented activation, but also significantly reduced survival and proliferation after activation, leading to overall decreased Th1 and Th17 polarization. Activated CD6-deficient T cells also showed impaired infiltration through brain microvascular endothelial cell monolayers. Furthermore, by developing CD6 humanized mice, we identified a mouse anti-human CD6 monoclonal antibody that is highly effective in treating established EAE without depleting T cells. These results suggest that (i) CD6 is a negative regulator of T-cell activation, (ii) at the same time, CD6 is a positive regulator of activated T-cell survival/proliferation and infiltration; and (iii) CD6 is a potential new target for treating MS and potentially other T-cell-driven autoimmune conditions.
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9
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Pinto M, Carmo AM. CD6 as a therapeutic target in autoimmune diseases: successes and challenges. BioDrugs 2013; 27:191-202. [PMID: 23568178 DOI: 10.1007/s40259-013-0027-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The transmembrane surface glycoprotein CD6 was one of the first antigens identified on T lymphocytes. The recognition of its involvement in T-cell signaling processes heralds the potential of CD6 as a target for therapy in a number of pathologies associated with imbalances in T-cell function. Its tissue distribution, cellular expression, and overall molecular structure are well described, and the interaction with its physiological ligand CD166 has been determined to the amino-acid level. Nevertheless, the involvement of CD6 in signaling pathways remains poorly characterized and its biological function is controversial; still unresolved are whether CD6 is a co-stimulatory molecule in T-cell activation or, similar to the related CD5 antigen, a modulator of intracellular signaling. Here we revisit the earliest attempts of modulating immune function using CD6 monoclonal antibodies, and review the current thinking behind the recent developments in immunotherapy targeting CD6. Notwithstanding the promises and hopes brought by monoclonals already in clinical trials, the fact is that very little is known about the mechanism of action of these reagents, whether they enhance the physiological role of the receptor or whether they may induce a completely novel biochemical response that might, nevertheless, be beneficially used to treat human immune pathology.
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Affiliation(s)
- Mafalda Pinto
- Cell Activation and Gene Expression Group, IBMC - Instituto de Biologia Molecular e Celular, Rua do Campo Alegre 823, 4150-180, Porto, Portugal
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10
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Nair P, Melarkode R, Rajkumar D, Montero E. CD6 synergistic co-stimulation promoting proinflammatory response is modulated without interfering with the activated leucocyte cell adhesion molecule interaction. Clin Exp Immunol 2010; 162:116-30. [PMID: 20726988 DOI: 10.1111/j.1365-2249.2010.04235.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
The CD6 membrane-proximal scavenger receptor cysteine-rich domain (SRCR3) includes the activated leucocyte cell adhesion molecule (ALCAM) binding site. CD6-ALCAM mediates a low-affinity interaction and their long-term engagement contributes to the immunological synapse. Their ligation may play a dual function, facilitating stable adhesion between the antigen-presenting cells and T cells during the early activation phase and later in the proliferative phase of the immune response. This study explored the strength of the CD6 co-stimulatory effect and whether CD6 co-stimulation with its natural ligand ALCAM also contributes to the lymphocyte effector differentiation. It was found that CD6-ALCAM interaction in vitro induced a synergistic co-stimulation of normal human peripheral blood mononuclear cells, defined by Bliss analysis. CD6 co-stimulation enhanced the CD3 proliferative efficacy by 23-34%. Moreover, a fivefold increment in the CD25 molecules number with a distinct gene transcription profile associated with cell activation, differentiation, survival and adhesion molecules was observed over CD3 single activation. Additionally, CD6 co-stimulation in excess interleukin (IL)-2 promotes a preferentially proinflammatory response. Besides, a CD6 membrane-distal domain (SRCR1)-specific non-depleting monoclonal antibody (mAb) inhibited the induced proliferation in the presence of ALCAM, reducing interferon-γ, IL-6 and tumour necrosis factor-α production. These results suggest that CD6 co-stimulation enhances the intrinsic activity of the CD3 activation pathway and contributes to the T helper type 1 subset commitment, enhancing the IL-2 sensitivity of recent activated human lymphocytes. It supports the role of CD6 as a susceptibility gene for pathological autoimmunity leading to tissue inflammation, and its relevance for targeted therapy.
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Affiliation(s)
- P Nair
- Research and Development, Biocon Ltd, Bangalore, India
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11
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Ferran M, Giménez-Arnau A, Bellosillo B, Pujol R, Santamaría-Babi L. Función efectora de linfocitos T CLA+ sobre queratinocitos autólogos en psoriasis. ACTAS DERMO-SIFILIOGRAFICAS 2008. [DOI: 10.1016/s0001-7310(08)76174-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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12
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Ofori-Acquah SF, King JA. Activated leukocyte cell adhesion molecule: a new paradox in cancer. Transl Res 2008; 151:122-8. [PMID: 18279810 DOI: 10.1016/j.trsl.2007.09.006] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2007] [Revised: 09/18/2007] [Accepted: 09/20/2007] [Indexed: 11/17/2022]
Abstract
The activated leukocyte cell adhesion molecule [ALCAM/CD166/melanoma metastasis clone D (MEMD)] is an immunoglobulin superfamily cell adhesion molecule. It is expressed developmentally in cells of all 3 embryonic lineages. The ALCAM expression is limited to subsets of cells in most adult tissues. ALCAM is localized at intercellular junctions in epithelium presumably as part of the adhesive complex that maintains tissue architecture. Over the past decade, alterations in expression of ALCAM have been reported in several human tumors (melanoma, prostate cancer, breast cancer, colorectal carcinoma, bladder cancer, and esophageal squamous cell carcinoma). This review summarizes the current knowledge of the role of ALCAM in malignancies.
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Affiliation(s)
- Solomon F Ofori-Acquah
- Department of Pediatrics, Aflac Cancer Center and Blood Disorders Services, Emory University School of Medicine, Atlanta, Ga, USA
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13
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Ferran M, Giménez-Arnau A, Bellosillo B, Pujol R, Santamaría-Babi L. Effector Function of CLA+ T Lymphocytes on Autologous Keratinocytes in Psoriasis. ACTAS DERMO-SIFILIOGRAFICAS 2008. [DOI: 10.1016/s1578-2190(08)70346-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
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14
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Black APB, Ardern-Jones MR, Kasprowicz V, Bowness P, Jones L, Bailey AS, Ogg GS. Human keratinocyte induction of rapid effector function in antigen-specific memory CD4+ and CD8+ T cells. Eur J Immunol 2007; 37:1485-93. [PMID: 17506032 DOI: 10.1002/eji.200636915] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The ability of human keratinocytes to present antigen to T cells is controversial and, indeed, it has been suggested that keratinocytes may promote T cell hyporesponsiveness. Furthermore, it is unclear whether keratinocytes can process antigen prior to MHC class I and class II presentation. We tested the ability of keratinocytes to induce functional responses in epitope-specific CD4+ and CD8+ memory T cells using peptides, protein and recombinant expression vectors as sources of antigen. Keratinocytes were able to efficiently process and present protein antigen to CD4+ T cells, resulting in cytokine secretion (Th1 and Th2). This interaction was dependent on keratinocyte expression of HLA class II and ICAM-1, which could be induced by IFN-gamma. In addition, keratinocytes could present virally encoded or exogenous peptide to CD8+ T cells, resulting in T cell cytokine production and target cell lysis. Finally, T cell lines grown using keratinocytes as stimulators showed no loss of function. These findings demonstrate that keratinocytes are able to efficiently process and present antigen to CD4+ and CD8+ memory T cells and induce functional responses. The findings have broad implications for the pathogenesis of cutaneous disease and for transcutaneous drug or vaccine delivery.
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Affiliation(s)
- Antony P B Black
- MRC Human Immunology Unit, Weatherall Institute of Molecular Medicine, University of Oxford, John Radcliffe Hospital, Oxford, UK
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15
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Abidi SMA, Saifullah MK, Zafiropulos MD, Kaput C, Bowen MA, Cotton C, Singer NG. CD166 expression, characterization, and localization in salivary epithelium: implications for function during sialoadenitis. J Clin Immunol 2006; 26:12-21. [PMID: 16418799 DOI: 10.1007/s10875-006-7119-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2005] [Accepted: 06/30/2005] [Indexed: 11/24/2022]
Abstract
CD166 is an Ig superfamily molecule that binds homotypically to itself and heterotypically to CD6. Interactions between CD6 and CD166 are important during immune development and in alloreactivity. CD166 is expressed at increased levels in selected cancers and in rheumatoid arthritis synovium. Knowledge that CD166 was expressed in normal human salivary epithelium led to these studies of CD166 and CD6 in diseased mouse salivary glands, that resemble pathology seen in the human disease, Sjögren's syndrome. We showed that in mouse salivary epithelium CD166 was expressed but that expression of CD166 did not necessarily predict its function. Recombinant soluble CD6-Ig bound to CD6 ligands (CD6L) on transformed and freshly isolated salivary epithelial cells. Cross-blocking studies showed that binding of CD6-Ig to salivary epithelium was in part dependent on CD166, but that CD6-Ig binding may also involve additional CD6L. Binding of CD6-Ig was sensitive to trypsin digestion but resistant to digestion by collagenase and sialidase. Anti-CD166 ab precipitated CD166 from salivary epithelium pre- and post-treatment with the pro-inflammatory cytokine IFN-gamma. In contrast CD6-Ig only precipitated CD166 from IFN-gamma treated cells. More extensive colocalization between CD166 and the actin cytoskeleton was observed in sialoadenitis epithelium compared to control. We conclude that during sialoadenitis, CD166 undergoes a gain of function, resulting in closer association with the actin cytoskeleton and increased capacity to bind CD6. We suggest that altered CD166 function may contribute to the pro-inflammatory milieu during sialoadenitis seen in Sjögren's syndrome.
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Affiliation(s)
- Syed M A Abidi
- Department of Pediatrics, CASE School of Medicine and Rainbow Babies and Children's Hospital, Cleveland, Ohio 44106, USA
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16
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Saifullah MK, Fox DA, Sarkar S, Abidi SMA, Endres J, Piktel J, Haqqi TM, Singer NG. Expression and Characterization of a Novel CD6 Ligand in Cells Derived from Joint and Epithelial Tissues. THE JOURNAL OF IMMUNOLOGY 2004; 173:6125-33. [PMID: 15528349 DOI: 10.4049/jimmunol.173.10.6125] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
CD6 is a T cell surface glycoprotein that plays an important role in interactions of thymocytes with thymic epithelial cells and in mature T cell interactions with selected nonprofessional tissue APCs. We describe a novel CD6 ligand (CD6L) 3A11 Ag that is distinct from the known CD6L (CD166). The 3A11 protein is expressed on cells derived from human thymus, skin, synovium, and cartilage, and its expression is enhanced by IFN-gamma. mAbs directed against the 3A11 Ag and CD166 exhibit distinct patterns of binding to a panel of cell lines. Confocal microscopy shows that both CD166 and the 3A11 Ag are expressed at the cell surface, and that these proteins colocalize. The 3A11 Ag has a molecular mass of 130 kDa and is immunoprecipitated using either mAb 3A11 or soluble CD6-Ig fusion protein. mAbs directed against individual CD6L were less potent than was soluble CD6-Ig fusion protein in reducing adhesion of T cells to adherent 3A11-positive epithelial cells in vitro, suggesting that these Abs recognize epitopes on the 3A11 Ag and CD166 that are distinct from CD6 binding sites. Finally, transfection of epithelial cells with CD166-specific small interfering RNAs significantly decreased CD166 expression without alteration in 3A11 Ag levels, and thus confirmed that these two CD6L are distinct. Taken together, our data identifies a novel 130-kDa CD6L that may mediate interactions of synovial and epithelial cells with T lymphocytes.
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MESH Headings
- Activated-Leukocyte Cell Adhesion Molecule/biosynthesis
- Activated-Leukocyte Cell Adhesion Molecule/chemistry
- Activated-Leukocyte Cell Adhesion Molecule/genetics
- Activated-Leukocyte Cell Adhesion Molecule/immunology
- Animals
- Antibodies, Monoclonal/metabolism
- Antibodies, Monoclonal/pharmacology
- Antigens, CD/metabolism
- Antigens, Differentiation, T-Lymphocyte/metabolism
- Arthritis, Rheumatoid/immunology
- Arthritis, Rheumatoid/metabolism
- Binding Sites, Antibody
- Blotting, Western
- Cell Adhesion/immunology
- Cell Line, Tumor
- Cell Membrane/immunology
- Cell Membrane/metabolism
- Cells, Cultured
- Epithelial Cells/immunology
- Epithelial Cells/metabolism
- Fibroblasts/immunology
- Fibroblasts/metabolism
- Humans
- Immunoprecipitation
- Interferon-gamma/pharmacology
- Ligands
- Mice
- Molecular Weight
- Peptides/chemistry
- Peptides/metabolism
- RNA, Small Interfering/pharmacology
- Synovial Membrane/immunology
- Synovial Membrane/metabolism
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Affiliation(s)
- Mohammad K Saifullah
- Case Western Reserve University School of Medicine, Rainbow Babies and Children's Hospital/University Hospitals of Cleveland, 11100 Euclid Avenue, Cleveland, OH 44106, USA
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17
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Singer NG, Fox DA, Haqqi TM, Beretta L, Endres JS, Prohaska S, Parnes JR, Bromberg J, Sramkoski RM. CD6: expression during development, apoptosis and selection of human and mouse thymocytes. Int Immunol 2002; 14:585-97. [PMID: 12039910 DOI: 10.1093/intimm/dxf025] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
CD6, a 130-kDa surface glycoprotein, is expressed primarily on cells of T lineage. A co-stimulatory role for CD6 in mature T cells has been shown, but the function of CD6 during thymocyte development is unknown. Since CD6 ligands are expressed on thymic epithelium, their interactions with CD6 could be important in thymic selection. In this report we show that CD6 is developmentally regulated in human and mouse thymocytes, and further demonstrate that increase in the level of CD6 expression correlates with expression of the selection marker CD69. We also show that activation via CD2 induces CD6 expression on mature human thymocytes and on a subset of immature human thymocytes that are resistant to apoptosis. In human and mouse thymocytes that express heterogeneous TCR, CD6 increases occur as double-positive thymocytes are selected to a single-positive stage. In contrast, in thymocytes from TCR transgenic mice, CD6 is barely increased following selection, suggesting that as functional avidity increases, requirements for CD6-dependent co-stimulation decrease. Taken together, these results indicate that during thymic development CD6-dependent signals may contribute both to thymocyte survival, and to the overall functional avidity of selection in both man and mouse.
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MESH Headings
- Animals
- Antigens, CD/metabolism
- Antigens, Differentiation, T-Lymphocyte/metabolism
- Apoptosis/immunology
- CD2 Antigens/metabolism
- Cell Differentiation
- Cell Survival
- Humans
- In Vitro Techniques
- Infant
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Transgenic
- Receptors, Antigen, T-Cell/genetics
- Receptors, Antigen, T-Cell/metabolism
- Signal Transduction
- T-Lymphocyte Subsets/cytology
- T-Lymphocyte Subsets/immunology
- T-Lymphocytes/cytology
- T-Lymphocytes/immunology
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Affiliation(s)
- Nora G Singer
- Case Western Reserve University School of Medicine and Rainbow Babies and Children's Hospital/University Hospitals of Cleveland, Cleveland, OH 44106, USA.
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18
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Rogers AN, Welte S, Black SJ, Baldwin CL. Partial cDNA sequences of bovine CD72 and CD166/ALCAM, ligands for SRCR-family accessory molecules CD5 and CD6. Vet Immunol Immunopathol 2002; 85:233-9. [PMID: 11943324 DOI: 10.1016/s0165-2427(02)00006-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Accessory/co-stimulatory molecules on the surface of T cells are capable of regulating activation signals. Two of these, CD5 and CD6, are molecules from the scavenger receptor cysteine rich (SRCR) superfamily. Partial sequences for the ligands of these molecules, known as CD72 and CD166 (or ALCAM), respectively, are provided for Bos taurus in this communication. Using highly conserved regions between the corresponding human and mouse genes, primers were designed and reverse transcription polymerase chain reaction was used to generate cDNA from bovine PBMC RNA. cDNA clones of several hundred base pairs in length were created and sequenced. The results showed 81% homology between bovine and human CD72 nucleotide sequences and 93% homology for the CD166 sequences. Similar levels of homology are seen between the corresponding human and mouse cDNA sequences.
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MESH Headings
- Activated-Leukocyte Cell Adhesion Molecule/genetics
- Activated-Leukocyte Cell Adhesion Molecule/immunology
- Activated-Leukocyte Cell Adhesion Molecule/metabolism
- Amino Acid Sequence
- Animals
- Antigens, CD/genetics
- Antigens, CD/immunology
- Antigens, CD/metabolism
- Antigens, Differentiation, B-Lymphocyte/genetics
- Antigens, Differentiation, B-Lymphocyte/immunology
- Antigens, Differentiation, B-Lymphocyte/metabolism
- Antigens, Differentiation, T-Lymphocyte/immunology
- Antigens, Differentiation, T-Lymphocyte/metabolism
- Base Sequence
- CD5 Antigens/immunology
- CD5 Antigens/metabolism
- Cattle/immunology
- Female
- Humans
- Leukocytes, Mononuclear/immunology
- Ligands
- Mice
- Molecular Sequence Data
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Homology, Amino Acid
- Sequence Homology, Nucleic Acid
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Affiliation(s)
- Aric N Rogers
- Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA 01003, USA.
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Levesque MC, Heinly CS, Whichard LP, Patel DD. Cytokine-regulated expression of activated leukocyte cell adhesion molecule (CD166) on monocyte-lineage cells and in rheumatoid arthritis synovium. ARTHRITIS AND RHEUMATISM 1998; 41:2221-9. [PMID: 9870879 DOI: 10.1002/1529-0131(199812)41:12<2221::aid-art18>3.0.co;2-i] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
OBJECTIVE To determine whether monocyte/macrophage expression of the CD6 ligand, activated leukocyte cell adhesion molecule (ALCAM) (CD166), is regulated by cytokines during inflammation in rheumatoid arthritis (RA). METHODS We used flow cytometry to test whether cytokines present in rheumatoid synovium could regulate ALCAM cell surface expression on peripheral blood (PB) monocytes and RA synovial fluid (SF) macrophages, and we examined ALCAM expression in situ in RA synovium by immunofluorescence. RESULTS The monocyte differentiation factors interleukin-3, macrophage colony-stimulating factor (M-CSF), and granulocyte-macrophage colony-stimulating factor augmented ALCAM expression on PB monocytes. ALCAM was expressed on monocyte-lineage cells in situ in inflamed synovium from patients with RA (9 of 9), but not in uninflamed synovium from patients with joint trauma (0 of 3). Furthermore, in vitro culture-induced ALCAM expression on PB monocytes and CD14+ RA SF cells was inhibited by an M-CSF neutralizing antibody. CONCLUSION ALCAM expression on PB and SF monocytes/macrophages is enhanced by M-CSF.
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Affiliation(s)
- M C Levesque
- Duke University Medical Center, Durham, North Carolina 27710, USA
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