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Pathni A, Wagh K, Rey-Suarez I, Upadhyaya A. Mechanical regulation of lymphocyte activation and function. J Cell Sci 2024; 137:jcs219030. [PMID: 38995113 PMCID: PMC11267459 DOI: 10.1242/jcs.219030] [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] [Indexed: 07/13/2024] Open
Abstract
Mechanosensing, or how cells sense and respond to the physical environment, is crucial for many aspects of biological function, ranging from cell movement during development to cancer metastasis, the immune response and gene expression driving cell fate determination. Relevant physical stimuli include the stiffness of the extracellular matrix, contractile forces, shear flows in blood vessels, complex topography of the cellular microenvironment and membrane protein mobility. Although mechanosensing has been more widely studied in non-immune cells, it has become increasingly clear that physical cues profoundly affect the signaling function of cells of the immune system. In this Review, we summarize recent studies on mechanical regulation of immune cells, specifically lymphocytes, and explore how the force-generating cytoskeletal machinery might mediate mechanosensing. We discuss general principles governing mechanical regulation of lymphocyte function, spanning from the molecular scale of receptor activation to cellular responses to mechanical stimuli.
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Affiliation(s)
- Aashli Pathni
- Biological Sciences Graduate Program, University of Maryland, College Park, MD 20742, USA
| | - Kaustubh Wagh
- Department of Physics, University of Maryland, College Park, MD 20742, USA
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ivan Rey-Suarez
- Insitute for Physical Science and Technology, University of Maryland, College Park, MD 20742, USA
- Microcore, Universidad de Los Andes, Bogota, DC 111711, USA
| | - Arpita Upadhyaya
- Biological Sciences Graduate Program, University of Maryland, College Park, MD 20742, USA
- Department of Physics, University of Maryland, College Park, MD 20742, USA
- Insitute for Physical Science and Technology, University of Maryland, College Park, MD 20742, USA
- Biophysics Program, University of Maryland, College Park, MD 20742, USA
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2
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Wheatley BA, Rey-Suarez I, Hourwitz MJ, Kerr S, Shroff H, Fourkas JT, Upadhyaya A. Nanotopography modulates cytoskeletal organization and dynamics during T cell activation. Mol Biol Cell 2022; 33:ar88. [PMID: 35830602 PMCID: PMC9582624 DOI: 10.1091/mbc.e21-12-0601] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Exposure to MHC-antigen complexes on the surface of antigen-presenting cells (APCs) activates T cells, inducing the formation of the immune synapse (IS). Antigen detection at the APC surface is thus a critical step in the adaptive immune response. The physical properties of antigen-presenting surfaces encountered by T cells in vivo are believed to modulate T cell activation and proliferation. Although stiffness and ligand mobility influence IS formation, the effect of the complex topography of the APC surface on this process is not well understood. Here we investigate how nanotopography modulates cytoskeletal dynamics and signaling during the early stages of T cell activation using high-resolution fluorescence microscopy on nanofabricated surfaces with parallel nanoridges of different spacings. We find that although nanoridges reduce the maximum spread area as compared with cells on flat surfaces, the ridges enhance the accumulation of actin and the signaling kinase ZAP-70 at the IS. Actin polymerization is more dynamic in the presence of ridges, which influence the directionality of both actin flows and microtubule (MT) growth. Our results demonstrate that the topography of the activating surface exerts both global effects on T cell morphology and local changes in actin and MT dynamics, collectively influencing T cell signaling.
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Affiliation(s)
- Brittany A Wheatley
- Department of Integrative Structural and Computational Biology and.,Skaggs Graduate School of Chemical and Biological Sciences, The Scripps Research Institute, Jupiter, FL 33458
| | - Ivan Rey-Suarez
- Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742
| | - Matt J Hourwitz
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742
| | - Sarah Kerr
- Department of Physics, University of Colorado, Boulder, CO 80302
| | - Hari Shroff
- National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD 20892
| | - John T Fourkas
- Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742.,Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742.,Maryland Quantum Materials Center, University of Maryland, College Park, MD 20742
| | - Arpita Upadhyaya
- Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742.,Department of Physics, University of Maryland, College Park, MD 20742
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Aly NAR, Rizk S, Aboul Enein A, El Desoukey N, Zawam H, Ahmed M, El Shikh ME, Pitzalis C. The role of lymphoid tissue SPARC in the pathogenesis and response to treatment of multiple myeloma. Front Oncol 2022; 12:1009993. [PMID: 36605435 PMCID: PMC9807864 DOI: 10.3389/fonc.2022.1009993] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2022] [Accepted: 11/25/2022] [Indexed: 12/24/2022] Open
Abstract
Background Despite the significant progress in the treatment of multiple myeloma (MM), the disease remains untreatable and its cure is still an unmet clinical need. Neoplastic transformation in MM is initiated in the germinal centers (GCs) of secondary lymphoid tissue (SLT) where B cells experience extensive somatic hypermutation induced by follicular dendritic cells (FDCs) and T-cell signals. Objective We reason that secreted protein acidic and rich in cysteine (SPARC), a common stromal motif expressed by FDCs at the origin (SLTs) and the destination (BM) of MM, plays a role in the pathogenesis of MM, and, here, we sought to investigate this role. Methods There were 107 BM biopsies from 57 MM patients (taken at different time points) together with 13 control specimens assessed for SPARC gene and protein expression and compared with tonsillar tissues. In addition, regulation of myeloma-promoting genes by SPARC-secreting FDCs was assessed in in vitro GC reactions (GCRs). Results SPARC gene expression was confirmed in both human primary (BM) and secondary (tonsils) lymphoid tissues, and the expression was significantly higher in the BM. Sparc was detectable in the BM and tonsillar lysates, co-localized with the FDC markers in both tissues, and stimulation of FDCs in vitro induced significantly higher levels of SPARC expression than unstimulated controls. In addition, SPARC inversely correlated with BM PC infiltration, ISS staging, and ECOG performance of the MM patients, and in vitro addition of FDCs to lymphocytes inhibited the expression of several oncogenes associated with malignant transformation of PCs. Conclusion FDC-SPARC inhibits several myelomagenic gene expression and inversely correlates with PC infiltration and MM progression. Therapeutic induction of SPARC expression through combinations of the current MM drugs, repositioning of non-MM drugs, or novel drug discovery could pave the way to better control MM in clinically severe and drug-resistant patients.
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Affiliation(s)
- Nesreen Amer Ramadan Aly
- Clinical and Chemical Pathology Department, Faculty of Medicine, Cairo University, Cairo, Egypt
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Samia Rizk
- Clinical and Chemical Pathology Department, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Azza Aboul Enein
- Clinical and Chemical Pathology Department, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Nermeen El Desoukey
- Clinical and Chemical Pathology Department, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Hamdy Zawam
- Clinical Oncology and Nuclear Radiation Department, Faculty of Medicine, Cairo University, Cairo, Egypt
| | - Manzoor Ahmed
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
| | - Mohey Eldin El Shikh
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
- *Correspondence: Mohey Eldin El Shikh,
| | - Costantino Pitzalis
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom
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Abd El-Aleem SA, Saber EA, Aziz NM, El-Sherif H, Abdelraof AM, Djouhri L. Follicular dendritic cells. J Cell Physiol 2021; 237:2019-2033. [PMID: 34918359 DOI: 10.1002/jcp.30662] [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: 10/11/2021] [Revised: 12/01/2021] [Accepted: 12/06/2021] [Indexed: 11/08/2022]
Abstract
Follicular dendritic cells (FDCs) are unique accessory immune cells that contribute to the regulation of humoral immunity. They are multitasker cells essential for the organization and maintenance of the lymphoid architecture, induction of germinal center reaction, production of B memory cells, and protection from autoimmune disorders. They perform their activities through both antigen-driven and chemical signaling to B cells. FDCs play a crucial role in the physiological regulation of the immune response. Dis-regulation of this immune response results when FDCs retain antigens for years. This provides a constant antigenic stimulation for B cells resulting in the development of immune disorders. Antigen trapped on FDCs is resistant to therapeutic intervention causing chronicity and recurrences. Beyond their physiological immunoregulatory functions, FDCs are involved in the pathogenesis of several immune-related disorders including HIV/AIDS, prion diseases, chronic inflammatory, and autoimmune disorders. FDCs have also been recently implicated in rare neoplasms of lymphoid and hematopoietic tissues. Understanding FDC biology is essential for better control of humoral immunity and opens the gate for therapeutic management of FDC-mediated immune disorders. Thus, the biology of FDCs has become a hot research area in the last couple of decades. In this review, we aim to provide a comprehensive overview of FDCs and their role in physiological and pathological conditions.
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Affiliation(s)
| | - Entesar Ali Saber
- Department of Histology and Cell Biology, Minia University, Minya, Egypt.,Department of Pharmacy, Deraya University, New Minia City, Egypt
| | - Neven M Aziz
- Department of Pharmacy, Deraya University, New Minia City, Egypt.,Department of Physiology, Minia Faculty of Medicine, Minia, Egypt
| | - Hani El-Sherif
- Department of Pharmacy, Deraya University, New Minia City, Egypt
| | - Asmaa M Abdelraof
- Public Health, Community, Environmental and Occupational Department, Faculty of Medicine, Beni-Suef University, Beni Suef, Egypt
| | - Laiche Djouhri
- Department of Physiology, College of Medicine (QU Health), Qatar University, Doha, Qatar
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The Migration of Human Follicular Dendritic Cell-Like Cell Is Facilitated by Matrix Metalloproteinase 3 Expression That Is Mediated through TNF α-ERK1/2-AP1 Signaling. J Immunol Res 2021; 2021:8483938. [PMID: 34222497 PMCID: PMC8225449 DOI: 10.1155/2021/8483938] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2021] [Revised: 05/31/2021] [Accepted: 06/04/2021] [Indexed: 11/17/2022] Open
Abstract
Follicular dendritic cells are important stromal components of the germinal center (GC) and have pivotal roles in maintaining the GC microenvironment for high-affinity antibody production. Tumor necrosis factor-α (TNFα) is essential for the development and functions of follicular dendritic cells. Despite the importance of follicular dendritic cells in humoral immunity, their molecular control mechanisms have yet to be fully elucidated due to the lack of an adequate investigation system. Here, we have used a unique human primary follicular dendritic cell-like cell (FDCLC) to demonstrate that the migration of these cells is enhanced by TNFα-mediated metalloproteinase 3 (MMP3) expression. MMP3 was found to be highly expressed in normal human GCs and markedly upregulated in human primary FDCLCs by TNFα. TNFα induced ERK1/2 phosphorylation and the transcription of MMP3 through AP1. TNFα treatment increased FDCLC migration, and a knockdown of MMP3 significantly reduced the TNFα-induced migration of FDCLCs. Overall, we have newly identified a control mechanism for the expression of MMP3 in FDCLCs that modulates their migration and may indicate an important role in GC biology. Since GCs are observed in the lesions of autoimmune diseases and lymphomas, targeting the MMP3/TNFα-mediated migration of stromal cells in the B cell follicle may have great potential as a future therapeutic modality against aberrant GC-associated disorders.
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Li X, Zhang Q, Zhang W, Ye G, Ma Y, Wen C, Gu S, Tang L, Li Y. Expanded circulating follicular dendritic cells facilitate immune responses in chronic HBV infection. J Transl Med 2020; 18:417. [PMID: 33160362 PMCID: PMC7648402 DOI: 10.1186/s12967-020-02584-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2020] [Accepted: 10/24/2020] [Indexed: 12/30/2022] Open
Abstract
Background The restoration of host hepatitis B virus (HBV)-specific antiviral immunity is an effective strategy for hepatitis B recovery. Follicular dendritic cells (FDCs) play a crucial role in immune regulation. The goal of the present study was to investigate the characteristics and functions of FDCs in chronic HBV infection. Methods The frequencies of FDCs in peripheral blood, liver, and spleen were measured in patients with chronic HBV infection. Isolated FDCs from splenic tissues of HBV-related liver cirrhosis-induced hypersplenism patients were cultured with autologous intrasplenic CD4+ T cells and CD19+ B cells. Results We observed that patients with chronic HBV infection had a significantly increased frequency of circulating FDCs compared to that of healthy controls. Additionally, the frequency of circulating FDCs was positively correlated with that of intrahepatic and intrasplenic counterparts. Moreover, positive correlations were observed between the frequencies of circulating FDCs and plasmablast and memory B cells, as well as C-X-C motif chemokine receptor type 5 (CXCR5)+CD4+ T cells and CXCR5+CD8+ T cells. Notably, in vitro experimental results demonstrated that FDCs derived from splenic tissues of chronic HBV patients facilitated interferon-γ and interleukin-21 production from autologous intrasplenic CD4+ T cells and promoted the proliferation of autologous intrasplenic CD19+ B cells. Conclusions Expanded FDCs in patients with chronic HBV infection may favor host immune responses against HBV. The identification of this unique population of cell may contribute to a better understanding of the immune regulatory mechanisms associated with chronic HBV infection and provide a potential immunotherapeutic target for this disease.
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Affiliation(s)
- Xiaoyi Li
- State Key Laboratory of Organ Failure Research, Guangdong Provincial Key Laboratory of Viral Hepatitis Research, Department of Infectious Diseases, Nanfang Hospital, Southern Medical University, No. 1838 North Guangzhou Avenue, Guangzhou, 510515, China
| | - Qifan Zhang
- Division of Hepatobiliopancreatic Surgery, Department of General Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, China
| | - Wanyue Zhang
- The Air Force Hospital of Southern Theater Command, Guangzhou, China
| | - Guofu Ye
- State Key Laboratory of Organ Failure Research, Guangdong Provincial Key Laboratory of Viral Hepatitis Research, Department of Infectious Diseases, Nanfang Hospital, Southern Medical University, No. 1838 North Guangzhou Avenue, Guangzhou, 510515, China
| | - Yanchen Ma
- State Key Laboratory of Organ Failure Research, Guangdong Provincial Key Laboratory of Viral Hepatitis Research, Department of Infectious Diseases, Nanfang Hospital, Southern Medical University, No. 1838 North Guangzhou Avenue, Guangzhou, 510515, China
| | - Chunhua Wen
- State Key Laboratory of Organ Failure Research, Guangdong Provincial Key Laboratory of Viral Hepatitis Research, Department of Infectious Diseases, Nanfang Hospital, Southern Medical University, No. 1838 North Guangzhou Avenue, Guangzhou, 510515, China
| | - Shuqin Gu
- State Key Laboratory of Organ Failure Research, Guangdong Provincial Key Laboratory of Viral Hepatitis Research, Department of Infectious Diseases, Nanfang Hospital, Southern Medical University, No. 1838 North Guangzhou Avenue, Guangzhou, 510515, China
| | - Libo Tang
- State Key Laboratory of Organ Failure Research, Guangdong Provincial Key Laboratory of Viral Hepatitis Research, Department of Infectious Diseases, Nanfang Hospital, Southern Medical University, No. 1838 North Guangzhou Avenue, Guangzhou, 510515, China
| | - Yongyin Li
- State Key Laboratory of Organ Failure Research, Guangdong Provincial Key Laboratory of Viral Hepatitis Research, Department of Infectious Diseases, Nanfang Hospital, Southern Medical University, No. 1838 North Guangzhou Avenue, Guangzhou, 510515, China.
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El Shikh MEM, Pitzalis C. Follicular dendritic cells in health and disease. Front Immunol 2012; 3:292. [PMID: 23049531 PMCID: PMC3448061 DOI: 10.3389/fimmu.2012.00292] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2012] [Accepted: 08/31/2012] [Indexed: 12/17/2022] Open
Abstract
Follicular dendritic cells (FDCs) are unique immune cells that contribute to the regulation of humoral immune responses. These cells are located in the B-cell follicles of secondary lymphoid tissues where they trap and retain antigens (Ags) in the form of highly immunogenic immune complexes (ICs) consisting of Ag plus specific antibody (Ab) and/or complement proteins. FDCs multimerize Ags and present them polyvalently to B-cells in periodically arranged arrays that extensively crosslink the B-cell receptors for Ag (BCRs). FDC-FcγRIIB mediates IC periodicity, and FDC-Ag presentation combined with other soluble and membrane bound signals contributed by FDCs, like FDC-BAFF, -IL-6, and -C4bBP, are essential for the induction of the germinal center (GC) reaction, the maintenance of serological memory, and the remarkable ability of FDC-Ags to induce specific Ab responses in the absence of cognate T-cell help. On the other hand, FDCs play a negative role in several disease conditions including chronic inflammatory diseases, autoimmune diseases, HIV/AIDS, prion diseases, and follicular lymphomas. Compared to other accessory immune cells, FDCs have received little attention, and their functions have not been fully elucidated. This review gives an overview of FDC structure, and recapitulates our current knowledge on the immunoregulatory functions of FDCs in health and disease. A better understanding of FDCs should permit better regulation of Ab responses to suit the therapeutic manipulation of regulated and dysregulated immune responses.
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Affiliation(s)
- Mohey Eldin M El Shikh
- Centre for Experimental Medicine and Rheumatology, William Harvey Research Institute, Barts and the London School of Medicine and Dentistry, Queen Mary University of London London, UK
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8
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Piconese S, Costanza M, Tripodo C, Sangaletti S, Musio S, Pittoni P, Poliani PL, Burocchi A, Passafaro AL, Gorzanelli A, Vitali C, Chiodoni C, Barnaba V, Pedotti R, Colombo MP. The matricellular protein SPARC supports follicular dendritic cell networking toward Th17 responses. J Autoimmun 2011; 37:300-10. [PMID: 21962567 DOI: 10.1016/j.jaut.2011.09.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2011] [Revised: 08/31/2011] [Accepted: 09/05/2011] [Indexed: 12/18/2022]
Abstract
Lymphnode swelling during immune responses is a transient, finely regulated tissue rearrangement, accomplished with the participation of the extracellular matrix. Here we show that murine and human reactive lymph nodes express SPARC in the germinal centres. Defective follicular dendritic cell networking in SPARC-deficient mice is accompanied by a severe delay in the arrangement of germinal centres and development of humoral autoimmunity, events that are linked to Th17 development. SPARC is required for the optimal and rapid differentiation of Th17 cells, accordingly we show delayed development of experimental autoimmune encephalomyelitis whose pathogenesis involves Th17. Not only host radioresistant cells, namely follicular dendritic cells, but also CD4(+) cells are the relevant sources of SPARC, in vivo. Th17 differentiation and germinal centre formation mutually depend on SPARC for a proper functional crosstalk. Indeed, Th17 cells can enter the germinal centres in SPARC-competent, but not SPARC-deficient, mice. In summary, SPARC optimizes the changes occurring in lymphoid extracellular matrix harboring complex interactions between follicular dendritic cells, B cells and Th17 cells.
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Affiliation(s)
- Silvia Piconese
- Molecular Immunology Unit, Department of Experimental Oncology and Molecular Medicine, AmadeoLab, Fondazione IRCCS Istituto Nazionale Tumori, via Amadeo 42, 20133 Milan, Italy
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9
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Buettner M, Pabst R, Bode U. Stromal cell heterogeneity in lymphoid organs. Trends Immunol 2010; 31:80-6. [DOI: 10.1016/j.it.2009.11.003] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2009] [Revised: 11/10/2009] [Accepted: 11/12/2009] [Indexed: 10/20/2022]
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11
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Balogh P, Fisi V, Szakal AK. Fibroblastic reticular cells of the peripheral lymphoid organs: Unique features of a ubiquitous cell type. Mol Immunol 2008; 46:1-7. [DOI: 10.1016/j.molimm.2008.07.014] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2008] [Accepted: 07/06/2008] [Indexed: 10/21/2022]
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12
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Allen CDC, Cyster JG. Follicular dendritic cell networks of primary follicles and germinal centers: phenotype and function. Semin Immunol 2008; 20:14-25. [PMID: 18261920 PMCID: PMC2366796 DOI: 10.1016/j.smim.2007.12.001] [Citation(s) in RCA: 310] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/13/2007] [Accepted: 12/06/2007] [Indexed: 12/11/2022]
Abstract
Follicular dendritic cells (FDCs) were identified decades ago by their ability to retain immune complexes and more recent findings indicate that they are a source of B cell attractants and trophic factors. New imaging studies have shown that B cells closely associate with their dendritic processes during migration. Here we will review the properties of these specialized follicular stromal cells and provide an update on the requirements for their maturation into phenotypically distinct cells within germinal center light and dark zones. We will then discuss current understanding of how they help support the B cell immune response.
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Affiliation(s)
- Christopher D C Allen
- Howard Hughes Medical Institute and Department of Microbiology and Immunology, 513 Parnassus Avenue, Box 0414, University of California, San Francisco, CA 94143-0414, USA.
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Ultrastructural study of highly enriched follicular dendritic cells reveals their morphology and the periodicity of immune complex binding. Cell Tissue Res 2008; 332:89-99. [PMID: 18236080 DOI: 10.1007/s00441-007-0566-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2007] [Accepted: 11/20/2007] [Indexed: 10/22/2022]
Abstract
Follicular dendritic cells (FDCs) are immune accessory cells found in the follicles of secondary lymphoid organs where they promote B cell maturation in germinal centers (GCs) that develop following antigen exposure. Recently, we published a method for isolating functional murine FDCs in high purity. We reasoned that disruption of FDC reticula in vivo would alter FDC morphology. The present study was undertaken to determine the morphological features of isolated FDCs. FDC-M1 and immune complex (IC) labeling were used to identify FDCs in isolated preparations. Results at the light-microscopic level revealed that isolated FDCs trapped ICs, expressed FDC-M1 and cadherins, but generally appeared non-dendritic. However, at the ultrastructural level, the majority of FDCs exhibited dendrites and typical euchromatic nuclei that appeared as single, bilobed, or double nuclei. Based on morphology, four varieties of FDCs were distinguishable, possibly indicative of differences in maturity. Remarkably, ICs trapped by FDCs showed a distinctive periodic arrangement consistent with that known to induce immune responses by thymus independent-2 (TI-2) antigens that engage and cross-link multiple B cell receptors. The ability of FDCs to trap ICs and then display these T-cell-dependent antigens with repeating periodicity suggests that multiple B cell receptors are cross-linked by antigen on FDCs, thus promoting B cell stimulation and proliferation. Rapid proliferation is characteristic of the GC reaction, and the arrangement of T-dependent antigens in this periodic fashion may help to explain the profuse B cell proliferation in the GC microenvironment.
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Murakami T, Chen X, Hase K, Sakamoto A, Nishigaki C, Ohno H. Splenic CD19-CD35+B220+ cells function as an inducer of follicular dendritic cell network formation. Blood 2007; 110:1215-24. [PMID: 17519390 PMCID: PMC1939903 DOI: 10.1182/blood-2007-01-068387] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Follicular dendritic cells (FDCs) form a reticular FDC network in the lymphoid follicle that is essential for the retention and presentation of native antigens in the form of antigen-antibody immune complexes (ICs) to B cells during secondary immune response. Although the presence of migrating precursors of FDCs has been hypothesized, their entity has not been elucidated. Here we report the identification of murine splenic CD19(-)CD11c(-)CD35(+)B220(+) cells as an inducer of FDC network formation. We demonstrated that CD19(-)-CD11c(-)CD35(+)B220(+) cells, together with stromal cells, had the remarkable ability to form lymphoid-follicle-like structures that contained B220(+)FDC-M1(+) reticular cells originally derived from CD19(-)-CD11c(-)CD35(+)B220(+) cells in the CD35(+) reticulum. Our results indicate that CD19(-)CD11c(-)CD35(+)B220(+) cells function as an inducer of FDC network formation and that the interaction between CD19(-)CD11c(-)CD35(+)B220(+) cells and stromal cells is required to initiate lymphoid follicle formation.
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MESH Headings
- Animals
- Antigens, CD19/metabolism
- Cell Differentiation
- Cell Lineage
- Dendritic Cells, Follicular/cytology
- Dendritic Cells, Follicular/metabolism
- Flow Cytometry
- Green Fluorescent Proteins/genetics
- Green Fluorescent Proteins/metabolism
- Immunophenotyping
- Killer Cells, Natural/classification
- Killer Cells, Natural/immunology
- Leukocyte Common Antigens/metabolism
- Mice
- Mice, Inbred BALB C
- Mice, Inbred C57BL
- Mice, Knockout
- Mice, Transgenic
- Receptors, Complement 3b/metabolism
- Spleen/cytology
- Stromal Cells/cytology
- Stromal Cells/immunology
- Stromal Cells/metabolism
- Tumor Necrosis Factor-alpha/genetics
- Tumor Necrosis Factor-alpha/physiology
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Affiliation(s)
- Takaya Murakami
- Laboratory for Epithelial Immunobiology, Rikagaku Kenkyusho (RIKEN) Research Center for Allergy and Immunology, Yokohama, Japan
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