PURPOSE: Pulmonary fibrosis (PF) is characterized by fibroblasts' proliferation,excessive collagen deposition,inflammation,reactive oxygen species' generation and apoptosis.The enzymes i-nitric oxide synthase(i-NOS)and metalloproteinase-9(MMP-9)are both very well known to be a significant part of the fibrotic pathway.Erythropoietin(EPO)is a multiple functional cytokine with anti-oxidative, anti-inflammatory and anti-apoptotic properties.Aim of this study was to search the role of EPO on bleomycin (BLM)- induced PF, by examining the effect of EPO on the expression of both enzymes in lung tissue of rats.
METHODS: Thirty-one Wistar rats(300g)were divided into five groups:Group 1(n=5):control amimals,Group 2(n=5):intratracheal(i.t)and intraperitoneal(i.p)injection of saline(0.5 ml/kg),Group 3(n=8):BLM hydrochloride(7.5 mg/kg)i.t injection,Group 4(n=8): BLM i.t injection(7.5 mg/kg)followed by EPO i.p injection(2000 iu/kg),Group 5(n=5):saline (0.5 ml/kg)i.t injection followed by EPO i.p injection (2000 iu/kg).All rats were sacrificed after 14 days.Immunohistochemical evaluation was performed for the expression of i-NOS and MMP-9.Lung injury and enzyme expression were estimated in 15 randomly selected fields/slide by Image Pro Plus software version 4.1.A scale of 4 grades was used for the evaluation of the results: 0-25%(A),25-50%(B),50-75%(C)and 75-100%(D).
RESULTS: In groups 1,2 and 5, i-NOS was expressed only in the grade A (100%)and MMP-9 was fairly expressed in grades A (20%)and B (80%).In group 3,i-NOS was expressed in the high grades B(25%), C(62.5%)and D(12.5%),and MMP-9 only in the two high grades C(75%)and D (25%).In group 4,both enzymes were expressed only in the low grades A(75% and 50% respectively)and B(25% and 50% respectively).The expression of i-NOS and MMP-9 took place in the high grades for group 3 (BLM group) and in the lower grades for group 4 (BLM+EPO group)(p<0.05 and p<0.001 respectively).
CONCLUSION: Administration of EPO after the BLM i.t injection, resulted in significant lower expression of i-NOS and MMP-9 compared with BLM group. Additional studies are required to clarify the underlying mechanisms of the protective action of EPO on PF.
CLINICAL IMPLICATIONS: These findings suggest that EPO may serve as a novel potential target for the therapeutic treatment of PF.
DISCLOSURE: Drosos Tsavlis, No Financial Disclosure Information; No Product/Research Disclosure Information