Altered alveolar macrophage function in calorie-restricted rats.

Abstract

Alveolar macrophage functions associated with clearance of bacteria from the lung were assessed in male Fischer 344 rats maintained on a 25% calorie-restricted diet. Calorie-restricted and ad libitum-fed (control) rats were exposed to concentrations of ozone known to compromise phagocytic function of alveolar macrophages. Ozone suppressed alveolar macrophage phagocytosis of latex beads in vitro in ad libitum-fed rats, but not in calorie-restricted rats. In fact, caloric restriction enhanced phagocytic function in both control and ozone-exposed animals. Ad libitum-fed rats exposed to ozone and challenged with Streptococcus zooepidemicus experienced a prolonged infection and influx of polymorphonuclear leukocytes (PMN), whereas calorie-restricted rats exposed to ozone cleared the bacteria in 24 h without an inflammatory response. Bacterial endotoxin-stimulated in vitro production of nitric oxide and tumor necrosis factor (TNF)-alpha as well as expression of TNF-alpha and interleukin-6 messenger RNAs were all lower in alveolar macrophages isolated from calorie-restricted rats. Together, the data suggest that caloric restriction enhances resistance to gram-positive bacteria, while lowering the production of proinflammatory mediators elicited by endotoxin, a component of gram-negative bacteria. Although increased bacterial resistance is considered beneficial, reduction in the lung's ability to induce inflammatory mediators can have both positive and pathophysiologic consequences.

• Authors: W Dong, M K Selgrade, I M Gilmour, R W Lange, P Park, M I Luster, F W Kari
• Journal: American journal of respiratory cell and molecular biology (Am J Respir Cell Mol Biol) Vol. 19 Issue 3 Pg. 462-9 (Sep 1998) ISSN: 1044-1549 [Print] United States
• PMID: 9730874 (Publication Type: Journal Article)

Chemical References

• Lipopolysaccharides
• RNA, Messenger
• Tumor Necrosis Factor-alpha
• Nitric Oxide
• Ozone

Topics

• Animals
• Cell Count (drug effects)
• Diet
• Inflammation (microbiology)
• Lipopolysaccharides (pharmacology)
• Lung (drug effects)
• Macrophages, Alveolar (drug effects)
• Male
• Neutrophils (metabolism)
• Nitric Oxide (metabolism)
• Ozone (pharmacology)
• Phagocytosis (drug effects)
• RNA, Messenger (metabolism)
• Rats
• Rats, Inbred F344
• Streptococcus (pathogenicity)
• Tumor Necrosis Factor-alpha (genetics, metabolism)