Respiratory syncytial virus (RSV) is the most important cause of lower respiratory tract infection in young children and the leading cause of infant hospitalization worldwide. Uncontrolled response to RSV is mediated by a toll-like receptor (TLR)-mediated immune response. Resveratrol possesses anti-RSV activity and is an inhibitor of the TRIF/TBK1/IRF-3 complex. We hypothesize that resveratrol inhibits the TRIF-dependent pathway through upregulation of SARM post-RSV infection. BALB/c mice were infected with RSV and were injected with resveratrol 1 h postinoculation. SARM short interfering RNA was administered to RSV-infected and resveratrol-treated mice. Lung function was measured by whole-body plethysmography, lung histopathology was examined, and lymphocytes in bronchoalveolar lavage fluid were quantified. SARM and TRIF protein expression were detected in the lung by Western blot analyses. The expression of gamma interferon in bronchoalveolar lavage fluid (BALF) was evaluated by enzyme-linked immunosorbent assay (ELISA). SARM expression was reduced and TRIF expression was increased after infection with RSV. Resveratrol increased SARM expression and decreased TRIF expression after RSV infection. SARM knockdown in resveratrol-treated mice enhanced gamma interferon production, RSV-induced airway inflammation, and airway hyperresponsiveness (AHR). Resveratrol decreased TRIF expression and prevented the RSV-mediated reduction of SARM expression. Resveratrol-mediated inhibition of the TRIF-dependent pathway may be dependent on SARM expression.
Importance: Our study provides insights into the regulation of innate immunity in response to RSV infection. The results suggest that resveratrol-mediated alterations in SARM have therapeutic potential against RSV immunopathology caused by deregulation of the TLR-mediated immune response. Ultimately, improved insight into the complex interplay between TLR adaptor proteins and the occurrence of severe RSV infection might lead to novel therapeutic treatment strategies, such as TLR adjuvants.