NOS2 and inflammation: However, streptomycin treatment reversed this situation, showing less expression of Arg1 and IL-10, with more expression of IL-1β and iNOS in the lungs of RSV-infected mice (Figure 4(e–h)), suggesting that M1-polarization of macrophages may be responsible for the exacerbation of lung inflammation of streptomycin-treated RSV-challenged mice.