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Bhandary YP, Shetty SK, Marudamuthu AS, Fu J, Pinson BM, Levin J, Shetty S. Role of p53-fibrinolytic system cross-talk in the regulation of quartz-induced lung injury. Toxicol Appl Pharmacol 2015; 283:92-8. [PMID: 25596429 DOI: 10.1016/j.taap.2015.01.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2014] [Revised: 01/02/2015] [Accepted: 01/05/2015] [Indexed: 11/16/2022]
Abstract
Silica is the major component of airborne dust generated by wind, manufacturing and/or demolition. Chronic occupational inhalation of silica dust containing crystalline quartz is by far the predominant form of silicosis in humans. Silicosis is a progressive lung disease that typically arises after a very long latency and is a major occupational concern with no known effective treatment. The mechanism of silicosis is not clearly understood. However, silicosis is associated with increased cell death, expression of redox enzymes and pro-fibrotic cytokines and chemokines. Since alveolar epithelial cell (AEC) death and disruption of alveolar fibrinolysis is often associated with both acute and chronic lung injuries, we explored whether p53-mediated changes in the urokinase-type plasminogen activator (uPA) system contributes to silica-induced lung injury. We further sought to determine whether caveolin-1 scaffolding domain peptide (CSP), which inhibits p53 expression, mitigates lung injury associated with exposure to silica. Lung tissues and AECs isolated from wild-type (WT) mice exposed to silica exhibit increased apoptosis, p53 and PAI-1, and suppression of uPA expression. Treatment of WT mice with CSP inhibits PAI-1, restores uPA expression and prevents AEC apoptosis by suppressing p53, which is otherwise induced in mice exposed to silica. The process involves CSP-mediated inhibition of serine-15 phosphorylation of p53 by inhibition of protein phosphatase 2A-C (PP2A-C) interaction with silica-induced caveolin-1 in AECs. These observations suggest that changes in the p53-uPA fibrinolytic system cross-talk contribute to lung injury caused by inhalation of silica dust containing crystalline quartz and is protected by CSP by targeting this pathway.
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Affiliation(s)
- Yashodhar P Bhandary
- Texas Lung Injury Institute, Department of Medicine, University of Texas Health Science Center at Tyler, 11937 US Highway 271, Tyler, TX 75708, USA
| | - Shwetha K Shetty
- Texas Lung Injury Institute, Department of Medicine, University of Texas Health Science Center at Tyler, 11937 US Highway 271, Tyler, TX 75708, USA
| | - Amarnath S Marudamuthu
- Texas Lung Injury Institute, Department of Medicine, University of Texas Health Science Center at Tyler, 11937 US Highway 271, Tyler, TX 75708, USA
| | - Jian Fu
- Texas Lung Injury Institute, Department of Medicine, University of Texas Health Science Center at Tyler, 11937 US Highway 271, Tyler, TX 75708, USA; Center for Research on Environmental Disease and Toxicology, College of Medicine, University of Kentucky, Lexington, KY 40536, USA
| | - Barbara M Pinson
- Occupational Medicine, Department of Medicine, University of Texas Health Science Center at Tyler, 11937 US Highway 271, Tyler, TX 75708, USA; Center for Research on Environmental Disease and Toxicology, College of Medicine, University of Kentucky, Lexington, KY 40536, USA
| | - Jeffrey Levin
- Occupational Medicine, Department of Medicine, University of Texas Health Science Center at Tyler, 11937 US Highway 271, Tyler, TX 75708, USA
| | - Sreerama Shetty
- Texas Lung Injury Institute, Department of Medicine, University of Texas Health Science Center at Tyler, 11937 US Highway 271, Tyler, TX 75708, USA.
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Beamer CA, Migliaccio CT, Jessop F, Trapkus M, Yuan D, Holian A. Innate immune processes are sufficient for driving silicosis in mice. J Leukoc Biol 2010; 88:547-57. [PMID: 20576854 DOI: 10.1189/jlb.0210108] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The lung is constantly exposed to potentially pathogenic particles and microorganisms. It has become evident recently that not only innate but also adaptive immune responses to particulates, such as SiO(2) entering the respiratory tract, are complex and dynamic events. Although the cellular mechanisms and anatomical consequences involved in the development of silicosis have been studied extensively, they still remain poorly understood. Based on their capacity for immune regulation, lymphocytes may play a key role in the respiratory response to environmental challenge by SiO(2). The objective of this study was to characterize the impact of SiO(2) exposure on respiratory immune processes, with particular emphasis on evaluating the importance of lymphocytes in the murine silicosis model. Therefore, lymphopenic mice, including NK-deficient, Rag1(-/-), or a combination (Rag1(-/-) NK-depleted), were used and demonstrated that SiO(2)-induced fibrosis and inflammation can occur independently of T, B, NK T, and NK cells. Studies in Rag1(-/-) mice suggest further that lymphocytes may participate in the regulation of SiO(2)-induced inflammation through modulation of the Nalp3 inflammasome. This observation may have clinical relevance in the treatment of inflammatory and fibrotic lung diseases that are refractory or respond suboptimally to current therapeutics.
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Affiliation(s)
- Celine A Beamer
- University of Montana, Department of Biomedical and Pharmaceutical Sciences, Center for Environmental Health Sciences, Skaggs Building, Room 285A, Missoula, MT 59812-1552, USA.
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3
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Jones KS. Assays on the influence of biomaterials on allogeneic rejection in tissue engineering. TISSUE ENGINEERING PART B-REVIEWS 2009; 14:407-17. [PMID: 18826337 DOI: 10.1089/ten.teb.2008.0264] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
In tissue engineering, innate responses to biomaterial scaffolds will affect rejection of allogeneic cells. Biomaterials directly influence innate and adaptive immune cell adhesion, reactive oxygen intermediate production, cytokine secretion, nuclear factor-kappa B nuclear translocation, gene expression, and cell surface markers, all of which are likely to affect allogeneic rejection responses. A major goal in tissue engineering is to induce transplant tolerance, potentially by manipulating the biomaterial component. This review describes methods of measuring responses of macrophages, dendritic cells, and T cells stimulated in vitro and in vivo and addresses key factors in assay development. Such tests include mixed leukocyte reactions, enzyme-linked immunosorbent spot assays, trans-vivo delayed-type hypersensitivity assays, and measurement of dendritic cell subsets and anti-donor antibodies; we propose extending these studies to tissue engineering.
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Affiliation(s)
- Kim S Jones
- Department of Chemical Engineering, McMaster University, Hamilton, Ontario, Canada.
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Carlsten C, de Roos AJ, Kaufman JD, Checkoway H, Wener M, Seixas N. Cell markers, cytokines, and immune parameters in cement mason apprentices. ACTA ACUST UNITED AC 2007; 57:147-53. [PMID: 17266079 DOI: 10.1002/art.22483] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
OBJECTIVE Cement masons are known to have significant silica exposure, and silica exposure and silicosis are thought to increase risk of autoimmune disease. Because the mechanisms remain obscure, with inconclusive reports of systemic immune effects following silica exposure, our goal was to identify potential early markers of silica-related immunologic and respiratory effects. METHODS We conducted a cross-sectional study of cement mason apprentices and electrician (control) apprentices. Demographics, dust exposure history, symptoms, spirometry, exhaled nitric oxide, and blood (for immunoglobulins, cytokines, cell counts, and surface markers) were obtained from 11 cement mason apprentices and a comparison group of 21 electrician apprentices. RESULTS Masons had significantly higher (P < 0.05) masonry dust exposure (42 versus 9 dust-hour-years), serum interleukin-1beta (IL-1beta; 12 versus 9 pg/ml), IL-2 (20 versus 8 pg/ml), IL-4 (193 versus 67 pg/ml), IL-10 (44 versus 21 pg/ml), and interferon-gamma (139 versus 65 pg/ml) compared with electricians. In contrast, masons had significantly lower percentages of CD25+ (12% versus 20%) and CD69+ (4% versus 9%) lymphocytes. CONCLUSION Mason apprentices had higher levels of serum proinflammatory cytokines and lower percentages of CD25+ and CD69+ lymphocytes than did electrician apprentices. These preliminary findings suggest that mason apprentices may be at greater risk of a systemic proinflammatory state that is potentially linked to immune dysregulation. Although distinct limitations of this preliminary data are recognized, this is consistent with early biologic effects leading to increased incidence of autoimmune disease among silica-exposed workers. Prospective studies are needed to validate these initial findings and clarify the temporal sequence of observed relationships.
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Affiliation(s)
- C Carlsten
- University of Washington, Department of Medicine, 4225 Roosevelt Way NE, Suite 100, Seattle, WA 98105, USA.
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Koo H, Ryu SH, Ahn HJ, Jung WK, Park YK, Kwon NH, Kim SH, Kim JM, Yoo BW, Choi SI, Davis WC, Park YH. Immunostimulatory effects of the anionic alkali mineral complex Barodon on equine lymphocytes. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2006; 13:1255-66. [PMID: 16943344 PMCID: PMC1656555 DOI: 10.1128/cvi.00150-06] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2006] [Revised: 06/14/2006] [Accepted: 08/23/2006] [Indexed: 11/20/2022]
Abstract
Previous studies have shown that the anionic alkali mineral complex BARODON has an immunoenhancing effect on pigs as an adjuvant and as a nonspecific immunostimulant. Likewise, the equine immune system has been defined with various monoclonal antibodies specific to equine leukocyte differentiation antigens to determine the possibility of enhancing equine resistance to respiratory diseases and promoting other immunostimulatory effects with the application of BARODON. Compared with the control group, after 3 weeks of treatment, BARODON-treated groups showed higher proportions of cells (P < 0.05) expressing major histocompatibility complex class II and CD2, CD4(+), CD4(+) CD25(+), CD8(+), and CD8(+) CD25(+) T lymphocytes, dendritic cells, and surface immunoglobulin M(+) B lymphocytes in peripheral blood, as well as enhanced cell proliferative responses with phytohemagglutinin and increased phagocytic activity against Streptococcus equi and Staphylococcus aureus strains with high antibiotic resistance, the bacteria frequently identified as etiologic agents of equine respiratory diseases at the Seoul Race Park in Seoul, Korea. This study shows that BARODON may act as an immunostimulator and can be an effective alternative to antimicrobial feed additives for nonspecific improvements in equine immune responses, particularly against respiratory diseases.
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Affiliation(s)
- Hyecheong Koo
- KRF Zoonotic Disease Priority Research Institute, College of Veterinary Medicine, Seoul National University, Sillim-dong, Gwanak-gu, Seoul, Republic of Korea
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Borges VM, Lopes MF, Falcão H, Leite-Júnior JH, Rocco PRM, Davidson WF, Linden R, Zin WA, DosReis GA. Apoptosis underlies immunopathogenic mechanisms in acute silicosis. Am J Respir Cell Mol Biol 2002; 27:78-84. [PMID: 12091249 DOI: 10.1165/ajrcmb.27.1.4717] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
We investigated immunopathogenic roles for apoptosis in acute murine silicosis. Intratracheal silica instillation induced pulmonary inflammation and enlarged thoracic lymph nodes. Lymphocytes from silica-exposed lymph nodes showed reduced mitogenic responses to T cell receptor (TCR) stimulation, and markedly increased activation-induced cell death, compared with control lymphocytes from saline-exposed lymph nodes. CD4(+) T cell death was mediated by Fas ligand, because CD4(+) T cells from Fas ligand-deficient gld mice did not undergo activation-induced apoptosis. Silica deposition also resulted in increased apoptosis associated with inflammatory infiltrates in lung parenchyma. In vivo treatment with caspase inhibitors reduced neutrophil accumulation, and alleviated inflammation in the lungs of silica-treated mice. These results suggest that silica-induced apoptosis plays an inflammatory role in the lung parenchyma, and creates immunologic abnormalities in regional lymph nodes, with pathogenic implications for the host.
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Affiliation(s)
- Valeria M Borges
- Instituto de Biofísica Carlos Chagas Filho, Federal University of Rio de Janeiro, Brazil
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Garn H, Friedetzky A, Kirchner A, Jäger R, Gemsa D. Experimental silicosis: a shift to a preferential IFN-gamma-based Th1 response in thoracic lymph nodes. Am J Physiol Lung Cell Mol Physiol 2000; 278:L1221-30. [PMID: 10835328 DOI: 10.1152/ajplung.2000.278.6.l1221] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
In chronic silicosis, mechanisms leading to lymphocyte activation are still poorly understood, although it is well known that not only the lung but also the draining lymph nodes are affected. In the present study, we investigated T-cell activation by analysis of cytokine expression in the enlarged thoracic lymph nodes of rats 2 mo after an 8-day silica aerosol exposure. In the case of helper T cell (Th) type 1 cytokines, we found a significant increase in interferon (IFN)-gamma mRNA expression, whereas interleukin (IL)-2 expression remained unchanged. In contrast, gene transcription for the Th2-type cytokines IL-4 and IL-10 was diminished. In addition, with use of an in vitro lymphocyte-macrophage coculture system, an enhanced IFN-gamma and a reduced IL-10 release were shown with cells from silicotic animals. With regard to IFN-gamma-inducing cytokines, we observed enhanced IL-12 mRNA levels in vivo, whereas IL-18 gene expression was slightly decreased. These data indicate that a persistent shift toward an IFN-gamma-dominated type 1 (Th1/cytotoxic T cell type 1) T-cell reaction pattern occurred within the thoracic lymph nodes of silicotic animals. Thus a mutual activation of lymphocytes and macrophages may maintain the chronic inflammatory changes that characterize silicosis.
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Affiliation(s)
- H Garn
- Institute of Immunology, Philipps University, D-35037 Marburg, Germany
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8
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Davis GS, Pfeiffer LM, Hemenway DR. Interferon-gamma production by specific lung lymphocyte phenotypes in silicosis in mice. Am J Respir Cell Mol Biol 2000; 22:491-501. [PMID: 10745030 DOI: 10.1165/ajrcmb.22.4.3599] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
We recently described overproduction of interferon (IFN)-gamma by lung lymphocytes in mice with silicosis (11% of cells in air-control versus 19% of cells from silica-exposed mice; Davis and colleagues, Am. J. Respir. Cell Mol. Biol. 1999;20:813-824). We hypothesized that the increased IFN-gamma production might be due to selective enrichment of one lymphocyte phenotype. To test this hypothesis, small mononuclear cells from lung digest preparations of mice exposed 4 mo previously to cristobalite silica (70 mg/m(3), 12 d, 5 h/d) or to sham-air were stained for intracellular cytokines and surface antigen phenotypes, and examined by flow cytometry. Air-sham mouse lung digests included CD4(+) (16%) and CD8(+) (6%) T cells, gammadelta T-cell antigen receptor (TCR)(+) CD4(-)CD8(-) T cells (3%), natural killer (NK) cells (15%), B cells (6%), and macrophages (12%). The total number of lung lymphocytes was increased 1.7-fold in silicosis, but the phenotype frequencies did not change significantly. In the control lungs IFN-gamma was produced by three major phenotypes of lymphocytes: 5% of CD4(+) T cells, 5% of gammadelta-TCR(+) CD4(-)CD8(-) T cells, and 2% of NK cells. The percentage of each type producing IFN-gamma was increased 2- to 3-fold in silicosis. When multiplied by cell number, the increased percentages yielded a 3- to 5-fold increase in the total number of each IFN- gamma-producing phenotype in the lung. Our results demonstrate no selective phenotype enrichment but upregulated IFN-gamma production by at least three lymphocyte phenotypes. IFN-gamma may be an important signal driving lymphocyte differentiation and macrophage activation in silicosis.
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Affiliation(s)
- G S Davis
- Departments of Medicine and Civil & Mechanical Engineering, University of Vermont, Burlington, VT, USA.
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Davis GS, Pfeiffer LM, Hemenway DR. Expansion of interferon-gamma-producing lung lymphocytes in mouse silicosis. Am J Respir Cell Mol Biol 1999; 20:813-24. [PMID: 10101015 DOI: 10.1165/ajrcmb.20.4.3407] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Silicosis is characterized by mononuclear cell inflammation with macrophage activation, accumulation of lymphocytes, and fibrosis. Interferon-gamma (IFN-gamma) is a lymphocyte cytokine with broad effects, particularly macrophage activation. Mice exposed to an aerosol of cristobalite silica (70 mg/m3, 12 d, 5 h/d) developed diffuse pulmonary pathologic changes with macrophage, lymphocyte, and neutrophil recruitment, and increased lung collagen. IFN-gamma messenger RNA (mRNA) was more abundant by semiquantitative reverse transcription-polymerase chain reaction in the lungs of silica-exposed mice than in control animals. IFN-gamma mRNA transcripts were detected by in situ hybridization with digoxigenin-labeled complementary DNA probes in normal mouse lung tissue within bronchial-associated lymphoid tissues (BALT). In silica- exposed mice, mononuclear cells with IFN-gamma mRNA were more numerous in the silicotic lesions and enlarged BALT structures. Lung-cell suspensions were prepared by enzyme digestion, stained with fluorescent-labeled antibodies against intracellular cytokines, and enumerated by flow cytometry. The percentage of cells producing IFN-gamma was increased in silicotic mice (19% versus 11%). Interleukin (IL)-4 mRNA transcripts were less abundant in the lung tissue from silica-exposed mice than in control mice. Cells staining for IL-4 mRNA were found rarely in either the air-sham or the silica-exposed mouse lungs, and almost all appeared to be within BALT structures. Approximately 3% of cells stained for IL-4 in the digested lungs from both groups. Similar cytokine patterns were observed in mediastinal lymph node/thymus and spleen tissues. The augmented IFN-gamma response, with IL-4 unchanged or decreased, in the lung lesions and lymphoid tissue of mice with silicosis suggests a Th-1-like lymphocyte-mediated immune-inflammatory response.
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Affiliation(s)
- G S Davis
- Departments of Medicine & Civil and Mechanical Engineering, University of Vermont, Burlington, Vermont, USA.
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10
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Suzuki N, Ohta K, Horiuchi T, Takizawa H, Ueda T, Kuwabara M, Shiga J, Ito K. T lymphocytes and silica-induced pulmonary inflammation and fibrosis in mice. Thorax 1996; 51:1036-42. [PMID: 8977606 PMCID: PMC472659 DOI: 10.1136/thx.51.10.1036] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
BACKGROUND Silica-induced pulmonary inflammation and fibrosis in animals provides a good model for chronic pulmonary inflammation and fibrosis. Although lymphocytes are implicated in the pathogenesis of pulmonary fibrosis, experimental models using silica-treated athymic nude mice have not been successful in showing the fibrogenic mechanism regulated by T cells. The aim of this study was to re-evaluate the role of T lymphocytes in the development of silicosis by comparing the response to silica administration of nude athymic mutants with that of euthymic animals. METHODS Suspensions of silica particles were transnasally administered to nude athymic mice (Balb/c nu/nu) as well as to their euthymic littermates (Balb/c nu/+). The degree of pulmonary inflammation and fibrosis was assessed on days 14, 28, and 56 based upon histological observation, analysis of collagen deposition in the lungs, and analysis of the cellular constituent, protein, and phospholipid content in the bronchoalveolar lavage fluid. RESULTS Histologically, athymic mice developed less severe interstitial pneumonitis than euthymic mice. In euthymic mice the lung hydroxyproline content increased with time after silica administration from 6.48 (0.38) micrograms hydroxyproline/mg dry lung weight on day 0 to 8.87 (0.41) micrograms/mg on day 56. A gradual increase in lung hydroxyproline content was also observed in athymic mice but the increase was significantly smaller than in euthymic mice (6.63 (0.43) micrograms/mg on day 0, 7.90 (0.19) micrograms/mg on day 56). Administration of silica resulted in an increase in the number of macrophages and neutrophils and in the total protein and phospholipid content of the bronchoalveolar lavage (BAL) fluid in both mouse strains. No significant difference was detected between athymic and euthymic mice in the numbers of macrophages, but the increase in neutrophils in the BAL fluid of athymic mice was significantly smaller than in euthymic mice on days 14 and 56. The total protein and phospholipid content of the BAL fluid from athymic mice was lower than that from euthymic mice. CONCLUSIONS T lymphocytes appear to be involved in the pathogenesis of silica-induced pneumonitis. Since pulmonary fibrosis develops even in nude athymic mice, T cells do not seem to play a primary part in fibrogenic response but they regulate, at least to some extent, the response of inflammatory cells and fibrogenesis of the lung.
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Affiliation(s)
- N Suzuki
- Department of Medicine and Physical Therapy, Faculty of Medicine, University of Tokyo, Japan
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Weissman DN, Ma JK, Rojanasakul Y, Hubbs AF. Immune Dysfunction in Silicosis: A Hypothesis. ACTA ACUST UNITED AC 1996. [DOI: 10.1080/1047322x.1996.10389997] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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Koeger AC, Lang T, Alcaix D, Milleron B, Rozenberg S, Chaibi P, Arnaud J, Mayaud C, Camus JP, Bourgeois P. Silica-associated connective tissue disease. A study of 24 cases. Medicine (Baltimore) 1995; 74:221-37. [PMID: 7565064 DOI: 10.1097/00005792-199509000-00001] [Citation(s) in RCA: 76] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
We prospectively studied all patients hospitalized for connective tissue disease (CTD) in our French rheumatology clinic from January 1979 to December 1989. Our aims were 1) to determine if CTDs associated with occupational exposure to silica (Si) are currently observed in a rheumatology clinic, and, if so, 2) to describe the major features of Si-associated CTD, and 3) to specify which individuals are affected by Si-associated CTD. Patients were divided into 2 groups based on their responses to a questionnaire: those who had been exposed to Si, and those who had no occupational exposure to Si. Among the 764 patients with CTD studied, 24 (3%) were patients with Si-associated CTD and 740 (97%) were patients with non-Si-associated CTD. The sex ratio between the 2 groups was significantly different with a high frequency of men and of immigrants in the Si-associated CTD group. Two thirds of the patients exposed to Si were male miners or sandblasters, but the other third had more unusual exposures to Si, which may involve members of all socio-economics sectors and both sexes, such as sculpture or exposure to abrasive powders. Progressive systemic sclerosis (PSS) was significantly more prevalent in the Si-associated CTD group. This group also consisted of patients with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), dermatomyositis (DM), and other autoimmune diseases. Si-associated CTD was characterized by the frequency of radiologic lung fibrosis, impaired pulmonary function tests, secondary Sjögren syndrome, and antinuclear antibodies. The number of mineral particles and crystalline Si content were raised in all the bronchoalveolar lavage specimens of Si-exposed patients but in none of those of nonexposed patients. In some cases of Si-associated CTD, the disease was reversible after early cessation of Si exposure. Epidemiologic studies are required to confirm our hypothesis that not only PSS and RA but also SLE and DM are associated with occupational exposure to Si. Pending such results, exposure to Si should be sought in the history of any patient with CTD, especially in a male patient with pulmonary signs, and if present, exposure should be stopped. In the meantime, steps should be taken to ensure that workers exposed to Si in all environments have adequate protection.
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Affiliation(s)
- A C Koeger
- Department of Rheumatology, Hôpital Pitié-Salpêtrière, Paris, France
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Abstract
A better understanding of early cellular events following pulmonary injury may permit the identification of those patterns of response which are destined to progress to fibrosis. Interactions between inflammatory, fibroblastic and epithelial cells appear to play crucial roles in fibrogenesis. Intercellular communication may be via "messages" delivered by soluble mediators or "handshakes" at sites of cell-to-cell contact. In this review, we question the validity of some prevailing concepts about the importance of growth factor secretion by alveolar macrophages; examine the possible role of activated T-lymphocytes in regulating macrophage production of mediators; and hypothesise that whereas fibroblast proliferation may primarily be stimulated by macrophage-derived cytokines, accumulation of collagen may be regulated by growth factors expressed by injured alveolar epithelial cells.
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Affiliation(s)
- R K Kumar
- School of Pathology, University of New South Wales, Sydney
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14
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Affiliation(s)
- U F Haustein
- Department of Dermatology, Leipzig University, Germany
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15
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Kumar RK, Velan GM, O'Grady R. Epidermal growth factor-like activity in bronchoalveolar lavage fluid in experimental silicosis. Growth Factors 1994; 10:163-70. [PMID: 7946405 DOI: 10.3109/08977199409000234] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We investigated whether development of pulmonary fibrosis following inhalational exposure of mice to silica (quartz) dust was accompanied by enhanced secretion of activity resembling epidermal growth factor (EGF). Mitogenic activity for pulmonary fibroblasts was assessed in bronchoalveolar lavage fluid (BALF) using a serum-free bioassay. Activity in BALF from mice exposed to nonfibrogenic titanium dioxide dust was comparable to that in BALF from normal animals. In contrast, mitogenic activity was significantly increased at 6 and 12 weeks after inhalation of silica particles, coinciding with the appearance of collagenised lesions in the lung. BALF from mice exposed to silica 6 weeks previously had significantly higher concentrations of growth factor(s) able to bind to EGF receptors on pulmonary fibroblasts. In parallel, macrophages within inflammatory lesions in the airspaces acquired immunoreactivity for EGF. The presence of an increased concentration of EGF-like growth factor(s) in BALF might constitute a marker of particle-induced pulmonary fibrosis.
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Affiliation(s)
- R K Kumar
- School of Pathology, University of New South Wales, Sydney, Australia
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Velan GM, Kumar RK, Cohen DD. Pulmonary inflammation and fibrosis following subacute inhalational exposure to silica: determinants of progression. Pathology 1993; 25:282-90. [PMID: 8265248 DOI: 10.3109/00313029309066590] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
To evaluate components of the pulmonary cellular response to inhaled silica that might be determinants of progression to fibrosis, we developed a model of the early stages of chronic human silicosis. Groups of mice were subacutely exposed either to alpha-quartz or to nonfibrogenic titanium dioxide dust as a control. Induction of lesions by inhaled silica was dependent upon the size distribution and dose of the particles. A novel observation was that low intensity exposure to silica evoked reversible inflammatory lesions that were characterized by focal aggregation of particle-laden alveolar macrophages near terminal airways. In contrast, higher intensity exposure elicited progressive pulmonary inflammation, including a significant perivascular influx of T-lymphocytes early in the response. The airspace inflammatory lesions exhibited a statistically significant decline in numerical density over time. Meanwhile, deposition of collagen was observed at perivascular locations, which were anatomically distinct from the initial foci of inflammation, and the numerical density of fibrotic lesions increased significantly with time. We speculate that this pattern of response might be related to alveolar clearance mechanisms being overwhelmed, followed by translocation and sequestration of particles in the interstitium, subsequently leading to T-lymphocyte recruitment and ultimately to the development of fibrosis.
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Affiliation(s)
- G M Velan
- School of Pathology, University of New South Wales, Sydney
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Velan GM, Kumar RK. IGSSPOT: an improved method for detection of individual cytokine-secreting cells. Immunol Lett 1992; 34:311-2. [PMID: 1487317 DOI: 10.1016/0165-2478(92)90230-l] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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