Objective To investigate the mechanism of cyclic adenosine monophosphate / protein kinase A signal transduction pathway in severe acute pancreatitis(SAP)-associated lung injury.Methods Seventy-two male healthy SD rats were completely randomized into three groups:sham operation (SO) group(n =8),SAP group and SAP plus H89 (cAMP inhibitor) group,then the latter two groups were divided into four sub-groups with eight rats in each sub-group according to the sampling time of 3,6,12 and 24 h,and the total numbers of groups were nine.The content change of TNF-α and IL-1β in serum,protein levels of cAMP-dependent protein kinase catalytic subunit (PKA C) and phosphorylated vasodilator-stimulated phosphoprotein(p-VASP) and the expression of VSAP mRNA in lung tissue were detected by enzyme-linked immunosorbent assay (ELISA),immunohistochemistry and quantitative real time PCR,respectively.Pathological changes of the pancreas and lung tissues were also observed.Results Compared with the SO group,the serum levels of TNF-α and IL-1β in the SAP group were obviously increased at different time points(P ＜0.05).Pathological changes of the pancreas and lung tissues were aggravated significantly.The protein levels of PKA C,p-VASP and the expression of VSAP mRNA in lung tissue were increased significantly (P ＜0.05)which peaked at 12 h in the SAP group [TNF-α was (266.07 ± 17.14) pg/mL,IL-1β(169.17 ±25.92) pg/mL,PKA C(210.69 ±6.32) × 103,p-VASP (56.62 ±0.57) × 103,VASP mRNA(2.06 ±0.21)],which had positive correlation with the serum level of TNF-α and IL-1β.Compared with the SAP group,pathological changes of the pancreas and lung tissues were alleviated significantly,the protein levels of PKA C,p-VASP and the expression of VSAP mRNA in lung tissue were decreased significantly in the SAP plus H89 group at different time points(P ＜ 0.05).Conclusion The cyclic adenosine monophosphate / protein kinase A signal transduction pathway is found to participate in the pathological process of SAP-associated lung injury through the up-regulations of TNF-α,IL-1 β and phospho-VASP.

BACKGROUNDIdiopathic pulmonary fibrosis (IPF) is a progressive diffuse parenchymal disease with a poor prognosis. A variety of cytokines and chemokines are involved in its pathophysiology. The aim of this study was to evaluate the clinical features in IPF patients with the expression of suppressor of cytokine signaling 1 (SOCS-1), which acts as a negative regulator of cytokine signaling.

METHODSIPF patients (n = 20) and healthy controls (n = 16) were included in this study. The expression of SOCS-1 was analyzed in peripheral blood mononuclear cells (PBMC) of subjects using RT-PCR. Interleukin 4 (IL-4), transforming growth factor β1 (TGF-β1) and type I collagen expression were also analyzed in each individual using enzyme-linked immunosorbent assay (ELISA). The clinical characteristics of IPF patients were delineated. These results were analyzed by SPSS13.0 statistics software.

RESULTSSOCS-1 mRNA expression was significantly decreased in the PBMC of IPF patients compared with healthy controls; serum levels of IL-4 and TGF-β1 were higher in IPF patients. The patients with lower expression of SOCS-1 developed lower percentage of forced vital capacity (FVC%) and DLCO/VA. A patients' SOCS-1 mRNA level was negatively correlated with serum levels of IL-4, and negatively correlated with their high-resolution computed tomography (HRCT) scores.

CONCLUSIONSSOCS-1 mRNA can be detected in PBMC, and it is down-regulated in IPF patients. The expression of SOCS-1 is associated with the severity of IPF patients' symptoms, so it might be the predictor of disease severity. SOCS-1 might play an important role in IPF by reducing the expression of the T helper type 2 (Th2) cell-related cytokine IL-4.

Adult ; Aged ; Aged, 80 and over ; Enzyme-Linked Immunosorbent Assay ; Female ; Humans ; Idiopathic Pulmonary Fibrosis ; metabolism ; Interleukin-4 ; metabolism ; Leukocytes, Mononuclear ; metabolism ; Male ; Middle Aged ; Suppressor of Cytokine Signaling 1 Protein ; Suppressor of Cytokine Signaling Proteins ; genetics ; metabolism ; Transforming Growth Factor beta1 ; metabolism