Soluble, but not transmembrane, TNF-? is required during influenza infection to limit the magnitude of immune responses and the extent of immunopathology.
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ABSTRACT: TNF-? is a pleotropic cytokine that has both proinflammatory and anti-inflammatory functions during influenza infection. TNF-? is first expressed as a transmembrane protein that is proteolytically processed to release a soluble form. Transmembrane TNF-? (memTNF-?) and soluble TNF-? (solTNF-?) have been shown to exert distinct tissue-protective or tissue-pathologic effects in several disease models. However, the relative contributions of memTNF-? or solTNF-? in regulating pulmonary immunopathology following influenza infection are unclear. Therefore, we performed intranasal influenza infection in mice exclusively expressing noncleavable memTNF-? or lacking TNF-? entirely and examined the outcomes. We found that solTNF-?, but not memTNF-?, was required to limit the size of the immune response and the extent of injury. In the absence of solTNF-?, there was a significant increase in the CD8(+) T cell response, including virus-specific CD8(+) T cells, which was due in part to an increased resistance to activation-induced cell death. We found that solTNF-? mediates these immunoregulatory effects primarily through TNFR1, because mice deficient in TNFR1, but not TNFR2, exhibited dysregulated immune responses and exacerbated injury similar to that observed in mice lacking solTNF-?. We also found that solTNF-? expression was required early during infection to regulate the magnitude of the CD8(+) T cell response, indicating that early inflammatory events are critical for the regulation of the effector phase. Taken together, these findings suggest that processing of memTNF-? to release solTNF-? is a critical event regulating the immune response during influenza infection.
SUBMITTER: DeBerge MP
PROVIDER: S-EPMC4048787 | biostudies-literature | 2014 Jun
REPOSITORIES: biostudies-literature
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