Protective effect of thymosin β4 on severe acute pancreatitis in rats

Objective To investigate the protective effects and mechanisms of intraperitoneal administration of thymosin β4 on severe acute pancreatitis in rats.Methods Fifty-four male Sprague-Dawley rats were randomly (random number) divided into sham operation (SO) group,severe acute pancreatitis (SAP) group and thymosin β4 (Tβ4) pretreatment group (n =18 in each group).SAP rat model was prepared by retrograde injection of 5％ sodium taurocholate into the biliopancreatic duct.Rats in Tβ4 group were treated with thymosin β4 (6 mg/kg) by intraperitoneal administration prior to SAP modeling.Six rats in each group were sacrificed at 3,6,12 hours,respectively after modeling.The serum levels of amylase,tumor necrosis factor-α (TNF-α),interleukin-1 β (IL-1 β),and interleukin-6 (IL-6)were detected,and pathological scores of the tissue of pancreas head were evaluated under light microscope.Pancreatic nuclear factor-kappa 1B (NF-κB) p65 and IκB α levels were detected by the Western blot.All data were analyzed by using the analysis of variauce or t test.Results The levels of serum amylase of SAP 3,6 and 12 hours groups were (3221 ±394) U/L,(4509 ±474) U/L and (6280 ±728) U/L,which were significantly higher than (2598±416) U/L,(3639 ±373) U/L and (4782 ±466) U/L of the Tβ4 groups (t =-2.666,-3.530,-4.245,P ＜ 0.05).The levels of serum TNF-α of the SAP 3,6 and 12 hours groups were (247.7 ± 18.5) pg/mL,(313.5 ± 17.7) pg/mL and (359.3 ±22.6) pg/mL,which were higher than (182.3 ± 13.6) pg/mL,(258.9 ± 14.9) pg/mL and (278.1 ± 16.3) pg/mL of the Tβ4 groups (t =-6.964,-5.769,-7.152,P ＜ 0.05).The levels of serum IL-1 β of the SAP 3,6 and 12 hours groups were (258.2±10.5) pg/mL,(345.1 ±22.0) pg/mL and (430.9 ±25.4) pg/mL,which were higher than (170.3 ± 12.4) pg/mL,(263.5 ± 13.3) pg/mL and (303.7 ± 16.1) pg/mL of the Tβ4 groups (t =-13.258,-7.762,-10.355,P ＜ 0.05).The levels of serum IL-6 of SAP 3,6 and 12 hours groups were (266.3 ±11.5) pg/mL,(355.0 ±24.4) pg/mL and (429.2 ±33.7) pg/ mL,which were higher than (171.1 ± 13.0) pg/mL,(234.9 ± 19.2) pg/mL and (277.2 ± 19.2) pg/ mL of the Tβ4 groups (t =-13.401,-9.474,-9.582,P ＜ 0.05).The pancreatic pathological scores of the SAP3,6 and 12 hours groups were (6.25 ±0.94),(8.83 ±0.82) and (12.08 ±1.16),which were higher than (4.17 ± 0.93),(6.33 ± 0.82) and (7.33 ± 1.25) of the Tβ4 groups (t =-3.867,-5.303,-6.823,P ＜ 0.05).The relative expression of pancreatic NF-κB p65 in SO group was (0.95 ±0.11),which was significantly lower than (2.40 ±0.17) of the SAP 12 hours group (t =-17.368,P＜ 0.05).The relative expression of pancreatic NF-κB p65 in Tβ4 group was 1.50 ± 0.10,which was significantly lower than SAP 12 hours group (t =10.917,P ＜0.05).The relative expression of pancreatic IκB α in SO group was (1.93 ±0.11),which was significantly higher than (0.78 ±0.18) of the SAP 12 hours group (t =13.260,P ＜ 0.05).The relative expression of pancreatic IκB α in Tβ4 group was (1.12±0.10),which was significantly higher than SAP 12 hours group (t =-4.112,P ＜ 0.05).Conclusions Thymosin β4 has the protective effect on SAP rat model,and the mechanism may be associated with inhibition of NF-κB signaling pathway and decreased proinflammatory cytokines. Key words: Acute abdomen;  Pancreatitis;  Thymosin β4;  Tumor necrosis factor-α;  Cell Signaling Pathway;  Nuclear factor-kappa B;  Actin;  Systemic inflammatory response syndrome;  Multiple organ dysfunction syndrome