Production of amphiregulin and recovery from influenza is greater in males than females

Meghan S. Vermillion, Rebecca L. Ursin, Denise I. T. Kuok, Landon G. vom Steeg, Nicholas Wohlgemuth, Olivia J. Hall, Ashley L. Fink, Eric Sasse, Andrew Nelson, Roland Ndeh, Sharon McGrath-Morrow, Wayne Mitzner, Michael C. W. Chan, Andrew Pekosz, Sabra L. Klein

Amphiregulin (AREG) is an epidermal growth factor that is a significant mediator of tissue repair at mucosal sites, including in the lungs during influenza A virus (IAV) infection. Previous research illustrates that males of reproductive ages experience less severe disease and recover faster than females following infection with IAV. Whether males and females differentially produce and utilize AREG for pulmonary repair after IAV infection was investigated using murine models on a C57BL/6 background and primary mouse and human epithelial cell culture systems. Following sublethal infection with 2009 H1N1 IAV, adult female mice experienced greater morbidity and pulmonary inflammation during the acute phase of infection as well as worse pulmonary function during the recovery phase of infection than males, despite having similar virus clearance kinetics. As compared with females, AREG expression was greater in the lungs of male mice as well as in primary respiratory epithelial cells derived from mouse and human male donors, in response to H1N1 IAVs. Internalization of the epidermal growth factor receptor (EGFR) was also greater in respiratory epithelial cells derived from male than female mice. IAV infection of Areg knock-out (Areg-/-) mice eliminated sex differences in IAV pathogenesis, with a more significant role for AREG in infection of male compared to female mice. Deletion of Areg had no effect on virus replication kinetics in either sex. Gonadectomy and treatment of either wild-type or Areg-/- males with testosterone improved the outcome of IAV as compared with their placebo-treated conspecifics. Taken together, these data show that elevated levels of testosterone and AREG, either independently or in combination, improve resilience (i.e., repair and recovery of damaged tissue) and contribute to better influenza outcomes in males compared with females.