Temporal Relationships Between Biochemical Mediators of Lung Damage and Fibrosis After Silica Inhalation in Rats

Details

• Personal Author:
  Barger M ; Castranova, Vincent ; Hubbs, Ann F. ; Kahn A ; Ma JYC ; McLaurin JL ; Porter DW ; Ramsey D ; Robinson VA
• Description:
  Crystalline silica (quartz) is Ii well established inflammatory and fibrogenic occupational dust. Past studies have established numerous biochemical mediators of these processes, but the temporal relationships between them have not been determined. To investigate these temporal relationships, rats were exposed to filtered air (control) or silica aerosol of 15mg/m3 (6 hr/day, 5 days/week) and assays were conducted after 5, 10, 16, 20, 30, 41, 79 and 116 days of exposure. Rat lungs were lavaged to isolate bronchoalveolar lavage cells (BALC) and acellular bronchoalveolar lavage fluid (BALF). Pulmonary inflammation was monitored by measuring BALC polymorphonuclear leukocytes (PMN) and alveolar macrophages (AM) differential cell counts. Compared to control, PMN in BA.LC isolated from silica exposed rats were significantly increased after 5 days exposure, remained elevated unti1 41 days, then increased further. BALC AM also were increased in silica-exposed rats, but only after 41 days exposure. Silica cytotoxicity was monitored by analysis of BALF for Lactate dehydrogenase (LDH) and albumin. In silica-exposed rats, both LDH and albumin levels were increased versus control after 5 days exposure, remained relatively constant until day 41, then increased further. AM chemiluminesence, a measure of AM activation and reactive oxygen species production was higher in silica-exposed rats when compared to control. After 41 days of exposure, lung lipid peroxidation was also higher in silica-exposed rats. BALC secretion of TNF-alpha and IL-1, when considered on a per cell basis, was higher in silica-exposed versus control rats by 116 days exposure. Lung fibrosis was confirmed by increased hydroxyproline levels in. the lungs of silica-exposed but not control rats after 116 days exposure. These data indicate that a progressively severe inflammatory reaction occurs in response to inhaled silica and begins to establish the temporal relationships between the various components of the inflammatory response and the development of pulmonary fibrosis. [Description provided by NIOSH]
• Subjects:
  Air Pollutants, Occupational Aluminum Silicates Animals Chemistry Chemistry, Analytic Dust Environmental Monitoring Hazardous Substances Irritants Laboratories Lung Lung Diseases Occupational Health Particulate Matter Respiratory System Respiratory Tract Diseases Safety Silicon Dioxide Toxicology

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• Keywords:
  Airborne-dusts Airborne-fibers Airborne-particles Analytical-chemistry Analytical-methods Animal-studies Dust-exposure Dust-inhalation Dust-particles Exposure-assessment Laboratory-animals Particulate-dust Particulates Pulmonary-disorders Pulmonary-system-disorders Respiratory-irritants Respiratory-system-disorders Silica-dusts Silicates Statistical-analysis Toxic-materials Toxins

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• ISSN:
  1096-6080
• Document Type:
  Text
• Genre:
  Abstract or Summary
• Place as Subject:
  Louisiana ; Ohio ; OSHA Region 3 ; OSHA Region 5 ; OSHA Region 6 ; West Virginia
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  HELD - Health Effects Laboratory Division ; DBBS - Division of Biomedical and Behavioral Sciences
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  48
• NIOSHTIC Number:
  nn:20027958
• Citation:
  Toxicologist 1999 Mar; 48(1-S):132
• CAS Registry Number:
  Quartz (SiO2) (CAS RN 14808-60-7)
• Federal Fiscal Year:
  1999
• Peer Reviewed:
  False
• Source Full Name:
  The Toxicologist. Society of Toxicology 38th Annual Meeting, March 14-18, 1999, New Orleans, Louisiana
• Supplement:
  1-S
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:19c9162e55a7a30961621525c813d1b8bc22e39878ae93c6a36ad55f891dcae120f89649898d77ccaeb3e1198b20cd322d6496691460b9ecac82ad799a49e896
• Download URL:
  https://stacks.cdc.gov/view/cdc/189694/cdc_189694_DS1.pdf
• File Type:
  [PDF - 200.05 KB ]