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Journal of interferon & cytokine research : the official journal of the International Society for Interferon and Cytokine Research

Regulatory effect of interleukin-4 in the innate inflammatory response to Rhodococcus aurantiacus infection in mice.


PMID 25291432

Abstract

Interleukin (IL)-4 promotes the regression of granulomas during the late phase of Rhodococcus aurantiacus infection. In this study, the contribution of IL-4 to the initial response against this bacterium was investigated using IL-4-deficient mice. Compared with wild-type (WT) mice, IL-4-deficient mice displayed remarkably lower tumor necrosis factor (TNF)-α and IL-6 secretion in the liver, spleen, and blood at the initial phase of infection, along with improved survival. IL-4-deficient mice also showed diminished IL-10 secretion in the spleen and blood; however, hepatic IL-10 levels were similar to those observed in WT animals, and were concomitant with augmented interferon (IFN)-γ production and decreased bacterial burden in the liver at the early infection phase. Histological examination revealed reduced hepatic granuloma formation in infected IL-4-deficient mice. On challenge with heat-killed R. aurantiacus, IL-4-deficient mouse macrophages showed reduced expression of TNF-α, IL-6, and IL-10 at both the gene and protein levels compared with WT mouse cells. These findings indicate that during the initiation of R. aurantiacus-induced inflammation, IL-4 deficiency attenuates cytokine responses in macrophages, which contributes to amelioration in mouse survival and reduction of granulomatous inflammation, and augments a hepatic IFN-γ response which transiently accelerates bacterial elimination.