The Studies On The Effect Of Glaucocalyxin A(GLA)on Attenuating Pulmonary Fibrosis And Improving Survival Rate In Mice

Idiopathic pulmonary fibrosis(IPF)is a progressive interstitial lung disease with unclear etiology and poor prognosis.Despite numerous studies on the pathogenesis of IPF,only scant treatment options are available for the management of IPF.Glaucocalyxin A(GLA),an ent-Kaurane diterpenoid isolated from Rabdosia japonica(Burm.f.)var.glaucocalyx(Maxim.)Hara,has been demonstrated to exert anti-inflammatory,anti-neoplastic and anti-platelet activities.Objective Explore the therapeutic effect and mechanism of Glaucocalyxin A in bleomycin-induced pulmonary fibrosis.Methods Mice were anesthetized by intraperitoneal injection(i.p.)with 40mg/kg of pentobarbital sodium,followed by intratracheal instillation with 5mg/kg of bleomycin(BLM).Mice in the sham group received equal volumes of PBS(i.t.).Mice were intraperitoneally injected with 10mg/kg of GLA daily for 14 consecutive days following BLM challenge.Equal amount of vehicle(10%DMSO in phosphate buffer saline(PBS))was intraperitoneally injected as a control.A total of 40 mice was randomly assigned to four groups:(a)Control group(mice were given PBS and vehicle);(b)GLA group(mice were given PBS and GLA);(c)BLM group(mouse were given BLM and vehicle);(d)BLM+GLA group(mice were given BLM and GLA).Then we examed(1)Body weight and mortality to elucidate the prognosis.(2)Masson's trichrome staining and hydroxyproline concentrations to determine the deposition of collagen.(3)Myeloperoxidase activity in bronchoalveolar lavage fluid(B ALF)to evaluate the effect of GLA on neutrophil infiltration.(4)mRNA levels of the cytokines(IL-1?,IL-6,TNF-?,MCP-1)in lung tissue,TGF-?1 expression in BLF and the activation of NF-?B in lung tissue of mice with pulmonary fibrosis induced by BLM.Results Our results showed that intraperitoneal administration of GLA(10 mg/kg)significantly reduced collagen deposition and hydroxyproline content in mouse lungs treated with bleomycin.Importantly,GLA significantly improved survival in bleomycin treated mice.In addition,GLA reduced weight loss in mice that reflects cachexia due to pulmonary fibrosis.Mechanistically,GLA alleviated the infiltration of macrophages and neutrophils in lungs,as indicated by decreased CD68 level and myeloperoxidase activity.GLA also attenuated the increases of proinflammatory cytokines in lung tissue and bronchoalveolar lavage fluid induced by bleomycin.Furthermore,the activation of NF-?B(nuclear factor kappa-light-chain-enhancer of activated B cells)in fibrotic lungs was significantly inhibited by GLA.These results provide evidence that GLA can effectively ameliorate pulmonary fibrosis through the antagonism of leukocyte infiltration and proinflammatory cytokine production,suggesting that it may become a potential anti-fibrotic agent in IPF management.Conclusion GLA showed an anti-fibrotic potential and substantial survival benefits in pulmonary fibrosis via inhibition inflammation.