Repeated Exposure to 1–>3-Beta-Glucan Suppresses Lung Defense Responses and Slows the Pulmonary Clearance of Listeria monocytogenes in Rats

Details

• Personal Author:
  Antonini JM ; Roberts, Jennifer R. ; Young S
• Description:
  Chronic exposure to low levels of mold has been reported to increase susceptibility to respiratory infections. Currently, the mechanism is not well understood. This study investigated lung defense effects after repeated low-dose zymosan (a 1-->3-beta-glucan from yeast cell wall) exposure on bacterial infection (Listeria monocytogenes) in male Sprague-Dawley rats. On days 0, 3, 7 and 10, rats received one dose of zymosan A (0.6 mg/kg body weight each dose) via intratracheal instillation or vehicle control (saline). On day 17 (one week later), rats were intratracheally inoculated with 5x105 bacteria. Rats were euthanized on days 20, 22, and 24. Bacterial clearance was determined by measuring colony-forming units cultured from the left lungs. Bronchoalveolar lavage (BAL) was performed on the right lungs. Inflammation and lung injury were assessed by measuring (1) neutrophil (PMN) infiltration and (2) albumin and lactate dehydrogenase levels in BAL fluid. Multiple zymosan treatments induced greater lung injury and inflammation as indicated by elevations in PMN, LDH, and albumin at days 22 and 24 compared to control. In addition, repeated low-dose exposure to zymosan slowed the clearance of the bacteria at day 20 and 22 compared to controls, suggesting a possible suppression in lung immune responses. In contrast, previous results have shown that a single acute dose of zymosan at a concentration (2.5 mg/kg body-weight) equivalent to the total of the four repeated concentrations used in the current study enhanced lung immune responses and increased the rate of bacterial clearance from the lung. This study demonstrated the importance of treatment concentration and dosing regimen in understanding lung immune effects associated with 1-->3-beta-glucan exposure. [Description provided by NIOSH]
• Subjects:
  Animals Chemistry Laboratories Lung Lung Diseases Occupational Health Respiratory Function Tests Respiratory System Respiratory Tract Diseases Safety
• Keywords:
  Alveolar-cells Animal-studies Biodynamics Chemical-analysis Chemical-indicators Chemical-reactions Laboratory-animals Lung-cells Lung-function Lung-irritants Pulmonary-disorders Pulmonary-function-tests Pulmonary-system-disorders

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• ISSN:
  1096-6080
• Document Type:
  Text
• Genre:
  Abstract or Summary
• 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
• Pages in Document:
  104
• Volume:
  96
• Issue:
  1
• NIOSHTIC Number:
  nn:20031910
• Citation:
  Toxicologist 2007 Mar; 96(1):104
• Federal Fiscal Year:
  2007
• NORA Priority Area:
  Manufacturing
• Peer Reviewed:
  False
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:a825dd9ed25de530dadc4503eb63eb82cbde24f5fe3223205294673ab0d5ada014ecef32972079d5fe2069b6744a15ff28a56573fadbcabac32fe6135c3152a5
• Download URL:
  https://stacks.cdc.gov/view/cdc/186021/cdc_186021_DS1.pdf
• File Type:
  [PDF - 522.04 KB ]