Based on the concept that both H4R and GILZ drive the differentiation of Th1 into Th2 lymphocytes and that histaminergic drugs and GCs are involved in the resolution of chronic inflammation, we hypothesized a possible interaction between histamine, inflammatory mediators, and GILZ in preventing the progression of lung injury in a murine model of pulmonary fibrosis induced by bleomycin injection. This evidence concerns the gene HRH4 and pulmonary fibrosis.