CCR2 and infection: Although increased expression of CCL2 during influenza infection has been well-documented (Zhou et al., 2013; Guo et al., 2015), the effects of the CCL2/CCR2 pathway on the pathogenesis of infection are controversial (Dawson et al., 2000; Narasaraju et al., 2010; Maelfait et al., 2016).