ARG1 and Hepatic fibrosis: Models of acute lung damage or liver fibrosis caused by the helminths Nippostrongylus brasiliensis [8,9] or Schistosoma mansoni, respectively have demonstrated important roles for Arginase-1 (Arg1) and insulin-like growth factor 1 (IGF-1) expressing MΦ, and IL-9R-dependent production of innate lymphoid cells (ILCs) in controlling inflammation and tissue damage [9,16,17].