AIM: To investigate the potential protective effect of exogenous recombinant interleukin-22(r IL-22) on L-arginine-induced acute severe pancreatitis(SAP)-associated lung injury and the possible signaling pathway involved.METHODS: Balb/c mice were injected intraperitoneally with L-arginine to induce SAP. Recombinant mouse IL-22 was then administered subcutaneously to mice. Serum amylase levels and myeloperoxidase(MPO) activity in the lung tissue were measured after the L-arginine administration. Histopathology of the pancreas and lung was evaluated by hematoxylin and eosin(HE) staining. Expression of B cell lymphoma/leukemia-2(Bcl-2), Bcl-x L and IL-22RA1 m RNAs in the lung tissue was detected by real-time PCR. Expression and phosphorylation of STAT3 were analyzed by Western blot. RESULTS: Serum amylase levels and MPO activity in the lung tissue in the SAP group were significantly higher than those in the normal control group(P < 0.05). In addition, the animals in the SAP group showed significant pancreatic and lung injuries. The expression of Bcl-2 and Bcl-x L m RNAs in the SAP group was decreased markedly, while the IL-22RA1 m RNA expression was increased significantly relative to the normal control group(P < 0.05). Pretreatment with PBS did not significantly affect the serum amylase levels, MPO activity or expression of Bcl-2, Bcl-x L or IL-22RA1 m RNA(P > 0.05). Moreover, no significant differences in the degrees of pancreatic and lung injuries were observed between the PBS and SAP groups. However, the serum amylase levels and lung tissue MPO activity in the r IL-22 group were significantly lower than those in the SAP group(P < 0.05), and the injuries in the pancreas and lung were also improved. Compared with the PBS group, r IL-22 stimulated the expression of Bcl-2, Bcl-x L and IL-22RA1 m RNAs in the lung(P < 0.05). In addition, the ratio of p-STAT3 to STAT3 protein in the r IL-22 group was significantly higher than that in the PBS group(P < 0.05).CONCLUSION: Exogenous recombinant IL-22 protects mice against L-arginine-induced SAP-associated lung injury by enhancing the expression of anti-apoptosis genes through the STAT3 signaling pathway. AIM: To investigate the potential protective effect of exogenous recombinant interleukin-22 (rIL-22) on L-arginine-induced acute severe pancreatitis (SAP) -associated lung injury and the possible signaling pathway involved. METHODS: Balb / c mice were Recombinant mouse IL-22 was then administered subcutaneously to mice. Serum amylase levels and myeloperoxidase (MPO) activity in the lung tissue were measured after the L-arginine administration. Histopathology of the pancreas and lung was evaluated by hematoxylin and eosin (HE) staining. Expression of B cell lymphoma / leukemia-2 (Bcl-2), Bcl-x L and IL-22RA1 m RNAs in the lung tissue was detected by real-time PCR. phosphorylation of STAT3 was analyzed by Western blot. RESULTS: Serum amylase levels and MPO activity in the lung tissue in the SAP group were significantly higher than those in the normal control group (P <0.05). In addition, the animals in the SAP group showed s ignificant pancreatic and lung injuries. The expression of Bcl-2 and Bcl-x L m RNAs in the SAP group was decreased markedly, while the IL-22RA1 m RNA expression was increased significantly relative to the normal control group (P <0.05). Pretreatment with PBS did not significantly affect the serum amylase levels, MPO activity or expression of Bcl-2, Bcl-x L or IL-22RA1 m RNA (P> 0.05). Moreover, no significant differences in the degrees of pancreatic and lung injuries However, the serum amylase levels and lung tissue MPO activity in the r IL-22 group were significantly lower than those in the SAP group (P <0.05), and the injuries in the pancreas and lung Compared with the PBS group, r IL-22 stimulated the expression of Bcl-2, Bcl-x L and IL-22RA1 m RNAs in the lung (P <0.05) to STAT3 protein in the r IL-22 group was significantly higher than that in the PBS group (P <0.05) .CONCLUSION: Exorated recombinant IL-22 protects mice against L-arginine-induced SAP-associated lung injury by enhancing the expression of anti-apoptosis genes through the STAT3 signaling pathway.