Subchronic Silica Exposure Enhances Respiratory Defense Mechanisms and the Pulmonary Clearance of Listeria monocytogenes in Rats

Details

• Personal Author:
  Antonini JM ; Barger MW ; Butterworth L ; Castranova, Vincent ; Charron TG ; Ma JYC ; Roberts, Jennifer R. ; Yang H-M
• Description:
  Both Listeria monocytogenes infection and silica exposure have been shown to significantly alter immune responses. In this study, we evaluated the effect of preexposure to silica on lung defense mechanisms using a rat pulmonary L. monocytogenes infection model. Male Sprague-Dawley rats were instilled intratracheally with saline (vehicle control) or silica using either an acute treatment regimen (5 mg/kg; 3 days) or a subchronic treatment protocol (80 mg/kg; 35 days). At 3 or 35 days after silica instillation, the rats were inoculated intratracheally with either approximately 5000 or 500,000 L. monocytogenes. At 3, 5, and 7 days postinfection, the left lung was removed, homogenized, and cultured on brain heart infusion agar at 37 degrees C. The numbers of viable L. monocytogenes were counted after an overnight incubation. Bronchoalveolar lavage (BAL) was performed on the right lungs, and BAL cell differentials, acellular lactate dehydrogenase (LDH) activity and albumin content were determined. Alveolar macrophage (AM) chemiluminescence (CL) and phagocytosis were assessed as a measure of macrophage function. Lung-associated lymph nodes were removed, and lymphocytes were recovered and differentiated. Preexposure to silica significantly increased the pulmonary clearance of L. monocytogenes as compared to saline controls. Exposure to silica caused significant increases in BAL neutrophils, LDH and albumin, and lymph-nodal T cells and natural killer (NK) cells in infected and noninfected rats. CL and phagocytosis were also elevated in silica-treated rats. In summary, the results demonstrated that exposure of rats to silica enhanced pulmonary immune responses, as evidenced by increases in neutrophils, NK cells, T lymphocytes, and macrophage activation. These elevations in pulmonary immune response are likely responsible for the increase in pulmonary clearance of L. monocytogenes observed with preexposure to silica. [Description provided by NIOSH]
• Subjects:
  Aluminum Silicates Animals Immune System Laboratories Lung Lung Diseases Lymphatic System Occupational Health Respiratory System Respiratory Tract Diseases Safety Silicon Dioxide

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• Keywords:
  Animal Studies Immune Reaction Laboratory Animals Lung Disorders Lymph Nodes Pulmonary System Disorders Respiratory System Disorders Silica Dusts Silicates
• ISSN:
  0895-8378
• Document Type:
  Text
• Genre:
  Journal Article
• Place as Subject:
  OSHA Region 3 ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  HELD - Health Effects Laboratory Division
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  12
• Issue:
  11
• NIOSHTIC Number:
  nn:20020607
• Citation:
  Inhal Toxicol 2000 Nov; 12(11):1017-1036
• Contact Point Address:
  James M. Antonini, PhD, Health Effects Laboratory Division, National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV 26505, USA
• Email:
  jga6@cdc.gov
• CAS Registry Number:
  Quartz (SiO2) (CAS RN 14808-60-7)
• Federal Fiscal Year:
  2001
• Peer Reviewed:
  True
• Source Full Name:
  Inhalation Toxicology
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:06f0be2d7be4d2589f32b4c51c9f0af462b434387a71e86bb2038359b7590b7611592399048791dfa527376dc6efe97e37e7c52de1b2fc00172e285a9df35bec
• Download URL:
  https://stacks.cdc.gov/view/cdc/198307/cdc_198307_DS1.pdf
• File Type:
  [PDF - 576.56 KB ]