The Basic And Clinical Exploration Of The Therapeutic Strategies To Connective Tissue Disease Associated Fibrotic Disease

Objective:Most of the fibroproliferative diseases are intractable and always with poor prognosis.This article aims to explore the novel therapeutic strategies of two relatively common diseases belonging to the category of connective tissue disease,with fibrosis as one of its most important pathological manifestations-systemic sclerosis(SSc)and connective tissue disease-associated interstitial lung disease(CTD-ILD),including the efficiency of iguratimod in treating skin fibrosis of SSc animal models and the efficacy of low-dose cyclophosphamide combined with pirfenidone in patients with refractory CTD-ILD.These researches may provide some ideas for clinical practice.Method:1.Isolation and culture of healthy human skin fibroblasts and stimulate the fibroblasts by TGF-β to mimic the state of fibroblast overactivation in SSc patients.After the treatment with iguratimod,the expression of α-SMA,the content of collagen and the other extracellular matrix,and the expression of the important transcription factor in the fibrosis progress-Egr-1-were examined on different levels of gene expression to evaluate the inhibitory effect of ilamod on fibroblast activation and extracellular matrix synthesis and the possible mechanism of action.Verify the efficacy of iguratimod gavage and local skin application on skin fibrosis in bleomycin-induced systemic sclerosis mouse model and TSK-1 mice and Inhibition effect of Egr-1 and TGF-β expression in skin tissues.The fibrotic skin tissue of SSc patients was transplanted under the skin of nude mice,and the iguratimod suspension was injected locally.Exam the Inhibition effect of excessive activation of fibroblasts in skin tissue of patients with SSc by detecting collagen content in skin tissue and expression of fibroblasts Egr-1 and TGF-β in fibeoblasts.2.Monthly Intravenous cyclophosphamide 0.4g/m2 combined with daily oral administration of pirfenidone 600 mg in 7 patients with CTD-ILD who met the standards.The combination therapy was performed during 12 months after enrollment.PFT,6-minute walking distance,chest HRCT,SGRQ respiratory questionnaire were used to assess the condition of patients and we monitor the adverse enents of patients at the same time.Result:1.Iguratimod has an inhibitory effect on TGF-β-induced fibroblast activation(differentiation to myofibroblasts)and extracellular matrix synthesis.It also significantly inhibited the expression of Egr-1 in fibroblasts.2.iguratimod oral administration and skin application reduced the skin thickness and the number of α-SMA positive myofibroblasts in the dermis of bleomycin-induced systemic sclerosis mouse model At the same time,the expression of Egr-1 and TGF-β in the fibroblasts of skin tissue was inhibited.3.TSK-1 mice are intolerant of iguratimod oral administration,but can be tolerated with iguratimod skin topical application.Topical iguratimod skin application reduces the thickness of the subcutaneous fibrous tissue layer.4,iguratimod treatment can inhibit the expression of Egr-1 and TGF-β in fibroblasts in the skin tissue of patients with SSc,and inhibit the synthesis of collagen.5.In the cohort and 7 patients with CTD-ILD,We observed that after 12 months of combination therapy with cyclophosphamide and pirfenidone,the HRCT score,6-minute walking distance,total score of the SGRQ respiratory questionnaire,and lung function were improved in all patients.All patients successfully reduced the prednisolone dose to 10 mg within six months.No adverse events clearly associated with the use of cyclophosphamide or pirfenidone were observed.conclusion:iguratimod has potential anti-fibrotic effect and can alleviate the degree of skin fibrosis in animal models of systemic sclerosis.The significant inhibitory effect of iguratimod on the expression of Egr-1 in fibroblasts may be one of the mechanisms of its anti-fibrotic effect.;low-dose cyclophosphamide combined with pirfenidone showed good efficacy and tolerability in patients with refractory CTD-ILD,it is worthwhile to further validate the efficacy and safety of this therapy in a larger sample patient cohort.