The expression of chemokine CXC motif ligand 12, CXC chemokine receptor 4 and CXC chemokine receptor 7 in spleens of rats with cirrhosis and hypersplenism

Objective To investigate expression the of CXC motif ligand 12 (CXCL12)-CXC chemokine receptor 4 (CXCR4)/CXC chemokine receptor 7 (CXCR7) axis in the spleens of rats with cirrhosis and hypersplenism, provide theoretical basis for the further explore the mechanism of spleen fibrosis of cirrhosis and hypersplenism. Methods Fifty male SD rats were randomized into 2 groups: In normal control group (n=10) were fed normal saline (0.3 ml/100 g (twice per week for 8 weeks); In model group (n=40) were fed with the volume fraction of 40% carbon tetrachloride (CCL4) of peanut oil solution (0.3 ml/100 g, twice per week for 8 weeks). The establishment of animal models with cirrhotic hypersplenic models were indicated by pathology and hemogram.. Spleen fibrosis degree was assessed by Masson trichrome staining. The expression of chemokine receptors of CXCL12, CXCR4 and CXCR7 were investigated by immunohistochemical staining, Western blotting analysis and real-time quantitative reverse transcriptase-polymerase chain reaction (RT-qPCR). The comparison between the two groups were used the independent sample T test. Results Masson trichrome staining displayed that collagen fiber area in the spleen of rats induced by CCL4 is remarkably larger than the controls [(11.17±4.85)% vs. (2.83±0.90)%, t=7.939, P=0.000]. There was significance differences (t=2.351, P=0.025) in the spleen index between the models (3.14±0.98) mg/g and the controls (2.33±1.03) mg/g. Immunohistochemical staining revealed that the mean density of CXCL12, CXCR4 and CXCR7 was significantly increased in models compared with the controls [(8.89±4.89)×10-3vs. (2.89±1.11)×10-3,t=4.126, P=0.001; (8.78±4.67)×10-3vs. (2.03±0.45)×10-3,t=4.973, P=0.000; (8.47±3.97)×10-3 vs. (1.81±0.69)×10-3,t=5.644, P=0.000; respectively]. Meanwhile, the models displayed a higher rate of positive cells of CXCL12, CXCR4 and CXCR7 [(31.02±9.03)%vs. (20.62±8.88)%, t=3.112, P=0.004; (33.22±8.31)%vs. (18.81±6.23)%, t=4.170, P=0.001; (28.89±8.40)% vs. (10.49±2.99)%, t=6.293, P=0.000; respectively]. Moreover, Western blotting analysis showed that the protein expression of CXCL12, CXCR4 and CXCR7 in the models were higher than that in the controls (1.71±0.98 vs.0.39±0.13, t=6.366, P=0.000; 1.01±0.57 vs.0.32±0.11, t=5.550, P=0.000; 1.15±0.77 vs.0.51±0.31, t=3.348, P=0.002; respectively). In addition, RT-qPCR demonstrated that, as compared with the controls the mRNA expression of CXCL12, CXCR4 and CXCR7 were improved prominently in the models (3.48±0.90 vs.1.05±0.10, t=9.607, P=0.000; 1.99±0.34 vs.1.00±0.18, t=10.460, P=0.000; 2.53±0.59 vs.1.02±0.02, t=9.259, P=0.000; respectively). Besides, positive correlations (r=0.688, P=0.001; r=0.711, P=0.001; r=0.579, P=0.009; respectively) were found between the protein expression of CXCL12 (1.31±1.02), CXCR4 (0.80±0.57) and CXCR7 (0.96±0.72) and splenic collagen fiber area (8.65±5.62)%, and then the mRNA expression of CXCL12 (2.74±1.37), CXCR4 (1.69±0.55) and CXCR7 (2.07±0.87) were also closely correlated with (r=0.694, P=0.001; r=0.647, P=0.003; r=0.609, P=0.006; respectively) the splenic collagen fiber area (8.65±5.62)%. Conclusion The abnormal expression of CXCL12-CXCR4/CXCR7 axis in spleens of rats with cirrhosis and hypersplenism induced by CCL4 suggested that the signaling pathway plays an important role in fibrosis process of spleen associated to cirrhosis and hypersplenism Key words: CXC motif ligand 12-CXC chemokine receptor 4/CXC chemokine receptor 7 axis; Spleen fibrosis; Cirrhosis; Hypersplenism; Model, animal; Rats