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Shabbir S, Hu Y, He X, Huang K, Xu W. Toxicity and Impact of Silica Nanoparticles on the Configuration of Gut Microbiota in Immunodeficient Mice. Microorganisms 2023; 11:1183. [PMID: 37317157 DOI: 10.3390/microorganisms11051183] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2023] [Revised: 04/25/2023] [Accepted: 04/26/2023] [Indexed: 06/16/2023] Open
Abstract
Nanoparticles (NPs), having exceptional physicochemical and electrical characteristics with lower toxicity, have evolved as dynamic drug delivery carriers in living organisms. Potentially, the intragastric gavage of silica nanoparticles (SiNPs) affects gut microbiota profiles in immunodeficient mice. In this study, the impact of SiNPs of variable size and dosage was investigated in cyclophosphamide (Cy)-induced immunodeficient mice, specifically on their immune functions and gut microbiota, through physicochemical and metagenomic analysis. SiNPs of different sizes and doses were gavaged to Cy-induced immunodeficient mice for 12 days at an interval of 24 h to investigate their effects on immunological functions and the gut microbiome of mice. Our results showed that SiNPs had no significant toxicological effects on the cellular and hematological activities of immunodeficient mice. Furthermore, after the administration of different levels of SiNPs, no immune dysfunction was found in the immunosuppressed mice groups. However, gut-microbial studies and comparisons of characteristic bacterial diversity and compositions demonstrated that SiNPs significantly affect the abundance of different bacterial communities. LEfSe analysis revealed that SiNPs significantly increased the abundance of Lactobacillus, Sphingomonas, Sutterella, Akkermansia, and Prevotella, and potentially reduced Ruminococcus and Allobaculum. Thus, SiNPs significantly regulate and modify the configuration of the gut microbiota in immunodeficient mice. These dynamic variations in the intestinal bacterial community, abundance, and diversity provide new insight into the regulation and administration of silica-based NPs. This would be helpful for the further demonstration of the mechanism of action and prediction of the potential effects of SiNPs.
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Affiliation(s)
- Sana Shabbir
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
- Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing 100083, China
| | - Yanzhou Hu
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Xiaoyun He
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
- Key Laboratory of Safety Assessment of Genetically Modified Organism (Food Safety) (MOA), College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Kunlun Huang
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
- Key Laboratory of Safety Assessment of Genetically Modified Organism (Food Safety) (MOA), College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
| | - Wentao Xu
- College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
- Key Laboratory of Precision Nutrition and Food Quality, Department of Nutrition and Health, China Agricultural University, Beijing 100083, China
- Key Laboratory of Safety Assessment of Genetically Modified Organism (Food Safety) (MOA), College of Food Science and Nutritional Engineering, China Agricultural University, Beijing 100083, China
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Ramon-Luing LA, Olvera Y, Flores-Gonzalez J, Palacios Y, Carranza C, Aguilar-Duran Y, Vargas MA, Gutierrez N, Medina-Quero K, Chavez-Galan L. Diverse Cell Death Mechanisms Are Simultaneously Activated in Macrophages Infected by Virulent Mycobacterium tuberculosis. Pathogens 2022; 11:pathogens11050492. [PMID: 35631013 PMCID: PMC9147088 DOI: 10.3390/pathogens11050492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 04/18/2022] [Accepted: 04/19/2022] [Indexed: 11/16/2022] Open
Abstract
Macrophages are necessary to eliminate pathogens. However, some pathogens have developed mechanisms to avoid the immune response. One of them is modulating the cell death mechanism to favor pathogen survival. In this study, we evaluated if virulent Mycobacterium tuberculosis (M. tb) can simultaneously activate more than one cell death mechanism. We infected human monocyte-derived macrophages (MDM) in vitro with avirulent (H37Ra) and virulent (H37Rv) strains, and then we measured molecules involved in apoptosis, necroptosis, and pyroptosis. Our data showed that H37Rv infection increased the BCL-2 transcript and protein, decreased the BAX transcript, and increased phosphorylated BCL-2 at the protein level. Moreover, H37Rv infection increased the expression of the molecules involved in the necroptotic pathway, such as ASK1, p-38, RIPK1, RIPK3, and caspase-8, while H37Ra increased caspase-8 and decreased RIPK3 at the transcriptional level. In addition, NLRP3 and CASP1 expression was increased at low MOI in both strains, while IL-1β was independent of virulence but dependent on infection MOI, suggesting the activation of pyroptosis. These findings suggest that virulent M. tb inhibits the apoptosis mediated by BCL-2 family molecules but, at the same time, increases the expression of molecules involved in apoptosis, necroptosis, and pyroptosis at the transcriptional and protein levels, probably as a mechanism to avoid the immune response and guarantee its survival.
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Affiliation(s)
- Lucero A. Ramon-Luing
- Laboratory of Integrative Immunology, Instituto Nacional de Enfermedades Respiratorias “Ismael Cosío Villegas”, Mexico City 14080, Mexico; (L.A.R.-L.); (J.F.-G.); (Y.P.); (Y.A.-D.)
| | - Yessica Olvera
- Research Department, Military School of Graduate of Health, SEDENA, Mexico City 11200, Mexico; (Y.O.); (M.A.V.); (N.G.); (K.M.-Q.)
| | - Julio Flores-Gonzalez
- Laboratory of Integrative Immunology, Instituto Nacional de Enfermedades Respiratorias “Ismael Cosío Villegas”, Mexico City 14080, Mexico; (L.A.R.-L.); (J.F.-G.); (Y.P.); (Y.A.-D.)
| | - Yadira Palacios
- Laboratory of Integrative Immunology, Instituto Nacional de Enfermedades Respiratorias “Ismael Cosío Villegas”, Mexico City 14080, Mexico; (L.A.R.-L.); (J.F.-G.); (Y.P.); (Y.A.-D.)
| | - Claudia Carranza
- Laboratory of Tuberculosis Immunobiology, Instituto Nacional de Enfermedades Respiratorias “Ismael Cosio Villegas”, Mexico City 14080, Mexico;
| | - Yerany Aguilar-Duran
- Laboratory of Integrative Immunology, Instituto Nacional de Enfermedades Respiratorias “Ismael Cosío Villegas”, Mexico City 14080, Mexico; (L.A.R.-L.); (J.F.-G.); (Y.P.); (Y.A.-D.)
| | - Marco Antonio Vargas
- Research Department, Military School of Graduate of Health, SEDENA, Mexico City 11200, Mexico; (Y.O.); (M.A.V.); (N.G.); (K.M.-Q.)
| | - Neptali Gutierrez
- Research Department, Military School of Graduate of Health, SEDENA, Mexico City 11200, Mexico; (Y.O.); (M.A.V.); (N.G.); (K.M.-Q.)
| | - Karen Medina-Quero
- Research Department, Military School of Graduate of Health, SEDENA, Mexico City 11200, Mexico; (Y.O.); (M.A.V.); (N.G.); (K.M.-Q.)
| | - Leslie Chavez-Galan
- Laboratory of Integrative Immunology, Instituto Nacional de Enfermedades Respiratorias “Ismael Cosío Villegas”, Mexico City 14080, Mexico; (L.A.R.-L.); (J.F.-G.); (Y.P.); (Y.A.-D.)
- Correspondence: or ; Tel.: +52-5554871700 (ext. 5270)
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Ehrlich R, Akugizibwe P, Siegfried N, Rees D. The association between silica exposure, silicosis and tuberculosis: a systematic review and meta-analysis. BMC Public Health 2021; 21:953. [PMID: 34016067 PMCID: PMC8136154 DOI: 10.1186/s12889-021-10711-1] [Citation(s) in RCA: 45] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 03/25/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND While the association between occupational inhalation of silica dust and pulmonary tuberculosis has been known for over a century, there has never been a published systematic review, particularly of experience in the current era of less severe silicosis and treatable tuberculosis. We undertook a systematic review of the evidence for the association between (1) silicosis and pulmonary tuberculosis, and (2) silica exposure and pulmonary tuberculosis controlling for silicosis, and their respective exposure-response gradients. METHODS We searched PUBMED and EMBASE, and selected studies according to a priori inclusion criteria. We extracted, summarised and pooled the results of published case-control and cohort studies of silica exposure and/or silicosis and incident active tuberculosis. Study quality was assessed on the Newcastle-Ottawa Scale. Where meta-analysis was possible, effect estimates were pooled using inverse-variance weighted random-effects models. Otherwise narrative and graphic synthesis was undertaken. Confidence regarding overall effect estimates was assessed using the GRADE schema. RESULTS Nine studies met the inclusion criteria. Meta-analysis of eight studies of silicosis and tuberculosis yielded a pooled relative risk of 4.01 (95% confidence interval (CI) 2.88, 5.58). Exposure-response gradients were strong with a low silicosis severity threshold for increased risk. Our GRADE assessment was high confidence in a strong association. Meta-analysis of five studies of silica exposure controlling for or excluding silicosis yielded a pooled relative risk of 1.92 (95% CI 1.36, 2.73). Exposure-response gradients were observable in individual studies but not finely stratified enough to infer an exposure threshold. Our GRADE assessment was low confidence in the estimated effect owing to inconsistency and use of proxies for silica exposure. CONCLUSIONS The evidence is robust for a strongly elevated risk of tuberculosis with radiological silicosis, with a low disease severity threshold. The effect estimate is more uncertain for silica exposure without radiological silicosis. Research is needed, particularly cohort studies measuring silica exposure in different settings, to characterise the effect more accurately as well as the silica exposure threshold that could be used to prevent excess tuberculosis risk.
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Affiliation(s)
- Rodney Ehrlich
- School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa
| | - Paula Akugizibwe
- School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa
| | - Nandi Siegfried
- Independent Clinical Epidemiologist, Cape Town, South Africa
- Department of Psychiatry and Mental Health, University of Cape Town, Cape Town, South Africa
| | - David Rees
- National Institute for Occupational Health, Johannesburg, South Africa
- School of Public Health, University of the Witwatersrand, Johannesburg, South Africa
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Carranza C, Chavez-Galan L. Several Routes to the Same Destination: Inhibition of Phagosome-Lysosome Fusion by Mycobacterium tuberculosis. Am J Med Sci 2019; 357:184-194. [DOI: 10.1016/j.amjms.2018.12.003] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Revised: 11/29/2018] [Accepted: 12/06/2018] [Indexed: 02/04/2023]
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Konečný P, Ehrlich R, Gulumian M, Jacobs M. Immunity to the Dual Threat of Silica Exposure and Mycobacterium tuberculosis. Front Immunol 2019; 9:3069. [PMID: 30687311 PMCID: PMC6334662 DOI: 10.3389/fimmu.2018.03069] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 12/11/2018] [Indexed: 01/28/2023] Open
Abstract
Exposure to silica and the consequent development of silicosis are well-known health problems in countries with mining and other dust producing industries. Apart from its direct fibrotic effect on lung tissue, chronic and immunomodulatory character of silica causes susceptibility to tuberculosis (TB) leading to a significantly higher TB incidence in silica-exposed populations. The presence of silica particles in the lung and silicosis may facilitate initiation of tuberculous infection and progression to active TB, and exacerbate the course and outcome of TB, including prognosis and survival. However, the exact mechanisms of the involvement of silica in the pathological processes during mycobacterial infection are not yet fully understood. In this review, we focus on the host's immunological response to both silica and Mycobacterium tuberculosis, on agents of innate and adaptive immunity, and particularly on silica-induced immunological modifications in co-exposure that influence disease pathogenesis. We review what is known about the impact of silica and Mycobacterium tuberculosis or their co-exposure on the host's immune system, especially an impact that goes beyond an exclusive focus on macrophages as the first line of the defense. In both silicosis and TB, acquired immunity plays a major role in the restriction and/or elimination of pathogenic agents. Further research is needed to determine the effects of silica in adaptive immunity and in the pathogenesis of TB.
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Affiliation(s)
- Petr Konečný
- Centre for Environmental and Occupational Health, School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa.,Division of Immunology, Department of Pathology and Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa
| | - Rodney Ehrlich
- Centre for Environmental and Occupational Health, School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa
| | - Mary Gulumian
- National Health Laboratory Service, Department of Toxicology and Biochemistry, National Institute for Occupational Health, Johannesburg, South Africa.,Division of Molecular Medicine and Haematology, University of the Witwatersrand, Johannesburg, South Africa.,National Health Laboratory Service, Johannesburg, South Africa
| | - Muazzam Jacobs
- Division of Immunology, Department of Pathology and Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Cape Town, South Africa.,National Health Laboratory Service, Johannesburg, South Africa.,Immunology of Infectious Disease Research Unit, South African Medical Research Council, Cape Town, South Africa
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Sada-Ovalle I, Chávez-Galán L, Vasquez L, Aldriguetti S, Rosas-Perez I, Ramiréz-Venegas A, Perez-Padilla R, Torre-Bouscoulet L. Macrophage Exposure to Polycyclic Aromatic Hydrocarbons From Wood Smoke Reduces the Ability to Control Growth of Mycobacterium tuberculosis. Front Med (Lausanne) 2018; 5:309. [PMID: 30483506 PMCID: PMC6243050 DOI: 10.3389/fmed.2018.00309] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 10/19/2018] [Indexed: 11/13/2022] Open
Abstract
Use of solid fuels for cooking or home heating has been related to various diseases of the respiratory tract. Woodsmoke contains a mixture of carcinogenic polycyclic aromatic hydrocarbons (PAHs) and volatile organic compounds. Inhalation of these materials induces local and systemic changes in the immune system which may impair critical cell defense mechanisms; however, few studies have investigated the early effects that PAH exposures have on immune cells as macrophages. The aim of this study was to analyze if the pre-exposure to PAHs derived from woodsmoke deteriorates macrophage ability to control the intracellular growth of Mycobacterium tuberculosis. By using an in vitro experimental model, we analyzed the phenotype and some metabolic changes on THP-1 and monocyte-derived macrophages. Our results demonstrated that exposure to PAHs leads to cell activation and deteriorates mitochondrial function of the macrophage thus facilitating growth of M. tuberculosis.
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Affiliation(s)
- Isabel Sada-Ovalle
- Laboratorio de Inmunología Integrativa, Instituto Nacional de Enfermedades Respiratorias Ismael Cosío Villegas, Ciudad de México, Mexico
| | - Leslie Chávez-Galán
- Laboratorio de Inmunología Integrativa, Instituto Nacional de Enfermedades Respiratorias Ismael Cosío Villegas, Ciudad de México, Mexico
| | - Luis Vasquez
- Laboratorio de Inmunología Integrativa, Instituto Nacional de Enfermedades Respiratorias Ismael Cosío Villegas, Ciudad de México, Mexico
| | - Stepahnie Aldriguetti
- Laboratorio de Inmunología Integrativa, Instituto Nacional de Enfermedades Respiratorias Ismael Cosío Villegas, Ciudad de México, Mexico
| | - Irma Rosas-Perez
- Departamento de Ciencias Ambientales, Universidad Nacional Autonoma de Mexico, Ciudad de Mexico, Mexico
| | - Alejandra Ramiréz-Venegas
- Departmento de Tabaquismo, Instituto Nacional de Enfermedades Respiratorias Ismael Cosío Villegas, Ciudad de México, Mexico
| | - Rogelio Perez-Padilla
- Departmento de Tabaquismo, Instituto Nacional de Enfermedades Respiratorias Ismael Cosío Villegas, Ciudad de México, Mexico
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Abstract
The purpose of this commentary is to bring the neglected phenomenon of subradiological silicosis and its implications to the attention of readers. We define subradiological silicosis as silicosis detectable on pathological examination of lung tissue but not visible radiologically. For extent of the phenomenon, we draw on a study using a large South African autopsy database of deceased miners and chest radiographs taken in life. At an International Labour Organization threshold of >1/0 only 43% of all pathologically detected cases were detected on chest radiograph, and only 62% of those classified on pathology as "moderate or marked" silicosis. Subradiological silicosis has a number of implications for research and practice: for dose-response studies of silicosis; for studies of the relationship between silica and conditions such as tuberculosis, lung cancer, and autoimmune disease, including the mechanistic role of fibrogenesis; for prognostication in silica exposed workers; and for workers' compensation criteria.
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Affiliation(s)
- Rodney Ehrlich
- Centre for Occupational and Environmental Health Research; School of Public Health and Family Medicine; University of Cape Town; Cape Town South Africa
| | - Jill Murray
- School of Public Health; University of the Witwatersrand; Johannesburg South Africa
| | - David Rees
- National Institute for Occupational Health; and School of Public Health; University of the Witwatersrand; Johannesburg South Africa
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Low Dose BCG Infection as a Model for Macrophage Activation Maintaining Cell Viability. J Immunol Res 2016; 2016:4048235. [PMID: 27833923 PMCID: PMC5090099 DOI: 10.1155/2016/4048235] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 08/26/2016] [Accepted: 09/15/2016] [Indexed: 11/17/2022] Open
Abstract
Mycobacterium bovis BCG, the current vaccine against tuberculosis, is ingested by macrophages promoting the development of effector functions including cell death and microbicidal mechanisms. Despite accumulating reports on M. tuberculosis, mechanisms of BCG/macrophage interaction remain relatively undefined. In vivo, few bacilli are sufficient to establish a mycobacterial infection; however, in vitro studies systematically use high mycobacterium doses. In this study, we analyze macrophage/BCG interactions and microenvironment upon infection with low BCG doses and propose an in vitro model to study cell activation without affecting viability. We show that RAW macrophages infected with BCG at MOI 1 activated higher and sustained levels of proinflammatory cytokines and transcription factors while MOI 0.1 was more efficient for early stimulation of IL-1β, MCP-1, and KC. Both BCG infection doses induced iNOS and NO in a dose-dependent manner and maintained nuclear and mitochondrial structures. Microenvironment generated by MOI 1 induced macrophage proliferation but not MOI 0.1 infection. In conclusion, BCG infection at low dose is an efficient in vitro model to study macrophage/BCG interactions that maintains macrophage viability and mitochondrial structures. This represents a novel model that can be applied to BCG research fields including mycobacterial infections, cancer immunotherapy, and prevention of autoimmunity and allergies.
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Ming M, Luo Z, Lv S, Li C. Inhalation of inactivated‑Mycobacterium phlei prevents asthma‑mediated airway hyperresponsiveness and airway eosinophilia in mice by reducing IL‑5 and IL‑13 levels. Mol Med Rep 2016; 14:5343-5349. [PMID: 27779664 DOI: 10.3892/mmr.2016.5865] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Accepted: 10/04/2016] [Indexed: 11/06/2022] Open
Abstract
The present study aimed to investigate whether inhalation of inactivated‑Mycobacterium phlei could prevent airway hyperresponsiveness and airway eosinophilia. A total of 24 male Balb/c mice were randomly divided into three groups: Normal control group (group A), asthma model group (group B) and the intervention group (group C), (8 mice/group). Group A mice were sensitized and with challenged saline and group B with ovalbumin (OVA). Group C mice were administered with aerosol Mycobacterium phlei once daily prior to the allergen challenge. Airway responsiveness in each group was assessed. All the animals were sacrificed and lung tissues, blood samples and bronchoalveolar lavage fluid (BALF) were harvested. Cell fractionation and differential cells were counted in serum and BALF. HE staining and alcian blue/periodic acid Schiff staining were used to measure airway eosinophilic inflammation and mucus production. The levels of the cytokines IL‑5, IL‑13 and IgE were measured in lung and BALF as determined by ELISA and reverse transcription‑quantitative polymerase chain reaction assays. The results indicated that inactivated‑Mycobacterium phlei suppressed the airway hyperresponsiveness and mitigated airway eosinophilia induced by a methacholine challenge, and significantly reduced the levels of cytokines IL‑5 and IL‑13 in lung tissue and IgE level in BALF when compared with the OVA‑sensitized mice. In conclusion, inhalation of inactivated‑Mycobacterium phlei could reduce OVA‑induced airway hyperresponsiveness and may be a potential alternative therapy for allergic airway diseases.
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Affiliation(s)
- Moyu Ming
- Department of Respiratory Medicine, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi 530021, P.R. China
| | - Zhixi Luo
- Department of Respiratory Medicine, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi 530021, P.R. China
| | - Shengqiu Lv
- Department of Respiratory Medicine, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi 530021, P.R. China
| | - Chaoqian Li
- Department of Respiratory Medicine, The First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi 530021, P.R. China
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Beamer GL, Seaver BP, Jessop F, Shepherd DM, Beamer CA. Acute Exposure to Crystalline Silica Reduces Macrophage Activation in Response to Bacterial Lipoproteins. Front Immunol 2016; 7:49. [PMID: 26913035 PMCID: PMC4753301 DOI: 10.3389/fimmu.2016.00049] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 02/01/2016] [Indexed: 11/13/2022] Open
Abstract
Numerous studies have examined the relationship between alveolar macrophages (AMs) and crystalline silica (SiO2) using in vitro and in vivo immunotoxicity models; however, exactly how exposure to SiO2 alters the functionality of AM and the potential consequences for immunity to respiratory pathogens remains largely unknown. Because recognition and clearance of inhaled particulates and microbes are largely mediated by pattern recognition receptors (PRRs) on the surface of AM, we hypothesized that exposure to SiO2 limits the ability of AM to respond to bacterial challenge by altering PRR expression. Alveolar and bone marrow-derived macrophages downregulate TLR2 expression following acute SiO2 exposure (e.g., 4 h). Interestingly, these responses were dependent on interactions between SiO2 and the class A scavenger receptor CD204, but not MARCO. Furthermore, SiO2 exposure decreased uptake of fluorescently labeled Pam2CSK4 and Pam3CSK4, resulting in reduced secretion of IL-1β, but not IL-6. Collectively, our data suggest that SiO2 exposure alters AM phenotype, which in turn affects their ability to uptake and respond to bacterial lipoproteins.
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Affiliation(s)
- Gillian L Beamer
- Department of Infectious Diseases and Global Health, Cummings School of Veterinary Medicine, Tufts University , North Grafton, MA , USA
| | - Benjamin P Seaver
- Department of Biomedical and Pharmaceutical Sciences, University of Montana , Missoula, MT , USA
| | - Forrest Jessop
- Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, MT, USA; Center for Environmental Health Sciences, Missoula, MT, USA
| | - David M Shepherd
- Department of Biomedical and Pharmaceutical Sciences, University of Montana , Missoula, MT , USA
| | - Celine A Beamer
- Department of Biomedical and Pharmaceutical Sciences, University of Montana, Missoula, MT, USA; Center for Biomolecular Structure and Dynamics, Missoula, MT, USA
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