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Caloric restriction increases early susceptibility to influenza infection in young C57BL/6 mice despite an intact NK cell response
Author(s) -
Ritz Barry W,
Nogusa Shoko,
Gardner Elizabeth M
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a47-a
Subject(s) - immune system , granzyme b , immunology , intracellular , biology , interferon , virus , t cell , microbiology and biotechnology
Caloric Restriction (CR) extends lifespan in mice and postpones age‐related changes in immunity. We have shown previously that CR mice exhibited increased mortality, impaired viral clearance, and reduced natural killer (NK) cell activity during the primary response to influenza. Since we did not examine the immune response in young CR mice, we do not know if the effects of CR are dependent on advanced age. In this study, young CR and adlibitum (AL) C57BL/6 mice were infected with 100 HAU of influenza A virus (PR8) and monitored for 4 days post‐infection. CR mice exhibited reduced food intake, greater weight loss, and increased viral RNA in lungs on day 2 ( P <0.05) compared to the AL group. NK1.1+ cells from the lungs of both CR and AL mice demonstrated elevated intracellular granzyme B on day 2 ( P <0.001), the peak of NK cytotoxicity in AL mice in this model. Intracellular IFN‐γ production and CD25 expression on NK1.1+ cells, as well as systemic IL‐6, were increased in CR mice compared to AL mice on days 1, 3, and 4 ( P <0.05). These data suggest an independent and detrimental effect of CR on the immune response to primary influenza infection in young mice despite enhanced NK activation. Future studies will examine young and aged CR and AL mice in parallel and consider the influence of CR on the metabolic costs, i.e., energy expenditure, in response to influenza infection. These findings may have particular implications for the elderly who are at an increased risk for CR due to physical and socioeconomic obstacles.