Digoxin alleviates pulmonary fibrosis by regulating phosphatidylinositol-3-kinase/Akt signaling through inhibiting the activation of fibroblast: an in vivo and in vitro experiment / 中华危重病急救医学

Objective:To investigate the effect of digoxin on bleomycin-induced pulmonary fibrosis in mice, and investigate its possible mechanism through in vitro and in vivo experiments. Methods:① In vivo experiment: 60 C57/BL6J mice were randomly divided into control group, pulmonary fibrosis model group (model group), pirfenidone (300 mg/kg) group, digoxin 1.0 mg/kg and 0.2 mg/kg groups, with 12 mice in each group. The pulmonary fibrosis model of mice was reproduced by single intratracheal infusion of bleomycin (5 mg/kg). The control group was given the same amount of sterile normal saline. From the next day after modeling, each group was received corresponding drugs by intragastric administration once a day for 28 days. Control group and model group were given the same amount of normal saline. The mice were sacrificed and the lung tissue was collected to detect the lung coefficient. After hematoxylin-eosin (HE) and Masson staining, the lung tissue morphology and collagen changes were observed under light microscope. Immunohistochemistry was used to detect the positive expressions of α-smooth muscle actin (α-SMA) and extracellular matrix (ECM) collagen (COL-Ⅰ and COL-Ⅲ) in lung tissue. The protein expressions of ECM fibronectin (FN), transforming growth factor-β (TGF-β) and phosphorylation of Smad3 (p-Smad3) in lung tissue were detected by Western blotting. ② In vitro experiment: human embryonic lung fibroblast-1 (HFL-1) cells were cultured and divided into blank control group, fibroblast activation model group (model group), pirfenidone (2.5 mmol/L) group and digoxin 100 nmol/L and 50 nmol/L groups when cell density reached 70%-90%. After 3-hour treatment with corresponding drugs, except blank control group, the other groups were treated with TGF-β for 48 hours to establish fibroblast activation model. The expressions of α-SMA, FN and p-Smad3 proteins and the phosphorylations of phosphatidylinositol-3-kinase (PI3K)/Akt pathway proteins PI3K and Akt (p-PI3K, p-Akt) were detected by Western blotting. Results:① In vivo, compared with the control group, the alveolar structure of mice in the model group was significantly damaged, a large number of inflammatory cells infiltrated, collagen deposition in the lung interstitium was increased, the deposition of ECM in the lung tissue was also increased, and the expressions of α-SMA, FN, TGF-β and p-Smad3 protein were increased, indicating that the model of bleomycin-induced pulmonary fibrosis in mice was successfully prepared. Compared with the model group, digoxin significantly inhibited airway inflammation and collagen fiber deposition, reduced ECM deposition, and decreased the protein expressions of α-SMA, FN, TGF-β and p-Smad3, while the effect was better than that of the pirfenidone group, and the digoxin 1.0 mg/kg group had a better effect except FN [α-SMA ( A value): 5.37±1.10 vs. 9.51±1.66, TGF-β protein (TGF-β/GAPDH): 0.09±0.04 vs. 0.33±0.23, p-Smad3 protein (p-Smad3/GAPDH): 0.05±0.01 vs. 0.20±0.07, all P < 0.01]. ② In vitro, compared with the blank control group, the expressions of FN, α-SMA, p-Smad3 and PI3K/Akt signaling proteins in the model group were increased, indicating that the fibroblast activation model induced by TGF-β was successfully reproduced. Compared with the model group, digoxin significantly inhibited fibroblast activation, and decreased the expressions of FN, α-SMA, p-Smad3, and PI3K/Akt pathway proteins, moreover, the effect was better than that of the pirfenidone group, and decreased FN, SMA and p-Akt protein expressions were more obvious in digoxin 100 nmol/L group [FN protein (FN/GAPDH): 0.21±0.15 vs. 0.88±0.22, α-SMA protein (α-SMA/GAPDH): 0.20±0.01 vs. 0.50±0.08, p-Akt protein (p-Akt/GAPDH): 0.30±0.01 vs. 0.65±0.10, all P < 0.01]. Conclusion:Digoxin could suppress the pulmonary fibrosis in mice induced by bleomycin, which might be associated with the regulation of fibroblast activation via suppressing PI3K/Akt signaling pathway in a dose-dependent manner.

The Effect of Granulocyte-Macrophage Colony-Stimulating Factor on Human Dermal Fibroblast Proliferation

Granulocyte-Macrophage colony-stimulating factor(GM- CSF) is naturally generated protein that stimulates the survival, proliferation, and differentiation of myeloid progenitor cells. The determination of the molecular sequence of this protein by recombinant DNA technology enabled us to produce sufficient quantity for preclinical and clinical use. In the animal studies, rhGM-CSF to wounds has been reported to result in increased formation of granulation tissue, increased breaking strength, and reversal of wound contraction. A number of case reports have been published on the favorable effect of rhGM-CSF as a treatment for infected, nonhealing wounds, and ulcers. However, there are no clinical reports about the effect of GM-CSF on wound healing in normal patients. Therefore, in this report, we examined the effect of GM-CSF on the proliferation of human dermal fibroblasts which play a crucial role in wound healing process in vitro. To determine an optimal GM-CSF concentration for human dermal fibroblast proliferation, the cells were incubated with either one of 13 concentrations of GM-CSF(0 - 30mug/ml). The media used in this study was DMEM/F- 12(GIBCO, Grand Island, NY, USA). The fibroblasts were seeded at 1.5 x 104 cells/well in 500mul of medium including 10% fetal bovine serum and either one of 13 concentrations of GM-CSF in 24-well plates. The cells were incubated for 6 days at 5% CO2, 100% humidity at 37degrees C. On the 6th day of plating, fibroblast proliferation was determined by hematocytometer. Each concentration was tested 8 times.Low concentration of GM-CSF(below 5.0mug/ml) stimulated the proliferation of human dermal fibroblasts. How ever, high concentration of GM-CSF(over 10mug/ml) downregulated the proliferation of human dermal fibroblasts. The best fibroblast proliferation was seen at 1.0mug/ml of GM- CSF. These results demonstrated that GM-CSF influenced human dermal fibroblast proliferation and the GM-CSF concentration was critically important factor in vitro.

The Effect of Granulocyte-Macrophage Colony-Stimulating Factor on Human Dermal Fibroblast Proliferation

Granulocyte-Macrophage colony-stimulating factor(GM- CSF) is naturally generated protein that stimulates the survival, proliferation, and differentiation of myeloid progenitor cells. The determination of the molecular sequence of this protein by recombinant DNA technology enabled us to produce sufficient quantity for preclinical and clinical use. In the animal studies, rhGM-CSF to wounds has been reported to result in increased formation of granulation tissue, increased breaking strength, and reversal of wound contraction. A number of case reports have been published on the favorable effect of rhGM-CSF as a treatment for infected, nonhealing wounds, and ulcers. However, there are no clinical reports about the effect of GM-CSF on wound healing in normal patients. Therefore, in this report, we examined the effect of GM-CSF on the proliferation of human dermal fibroblasts which play a crucial role in wound healing process in vitro. To determine an optimal GM-CSF concentration for human dermal fibroblast proliferation, the cells were incubated with either one of 13 concentrations of GM-CSF(0 - 30mug/ml). The media used in this study was DMEM/F- 12(GIBCO, Grand Island, NY, USA). The fibroblasts were seeded at 1.5 x 104 cells/well in 500mul of medium including 10% fetal bovine serum and either one of 13 concentrations of GM-CSF in 24-well plates. The cells were incubated for 6 days at 5% CO2, 100% humidity at 37degrees C. On the 6th day of plating, fibroblast proliferation was determined by hematocytometer. Each concentration was tested 8 times.Low concentration of GM-CSF(below 5.0mug/ml) stimulated the proliferation of human dermal fibroblasts. How ever, high concentration of GM-CSF(over 10mug/ml) downregulated the proliferation of human dermal fibroblasts. The best fibroblast proliferation was seen at 1.0mug/ml of GM- CSF. These results demonstrated that GM-CSF influenced human dermal fibroblast proliferation and the GM-CSF concentration was critically important factor in vitro.

The Adequate Concentration of Subconjunctivally Injected Mitomycin c for the Prevention of Postoperative Adhesion in Strabisrnus

It. has been reported that, subconjunctival mitornycin c is strongiy effective in the reduction of postoperative fibrosis and adhesion. However we have to be cautious in using it clinically because of severe complications, scleral necrosis, endophthalmitis, etc. To find out the adequate concentration of mitomycin C, the authors performed 3mm recession of the superior rectus muscle (SR) in the left sys of 24 rabbits which were divided into 4 groups. Each group was composed of 6 rabbits. The 0.1%of 0.9% normal saline, 0.005% 0.01%, and 0.02% mitomycin c were injected subcounctivally through the site of SR recession in each group, respectively. The severity of the adhesion between SR and its surrounding tissues and the reduction of fibroblast. proliferation were evaluated histopathologically with the light microscope one month after surgery. The 0.01% and 0.02%mitomycin C-injected groups demonstrated considerable inhibition of postoperative adhesion and fibroblastic proliferation (p0. 15), This study reveals that the concentration of mitomycin c between 0.01% and 0.02% may prevent postoperative adhesions effectively after strabisrnus surgery. Further studies are needed to demonstrate the lowest concentration of mitoniycin c to prevent postoperative adhesion effectively without any com.plicat.ions in clinical use.

Effect of gamma-interferon on fibroblast proliferation and collagen synthesis after glaucoma filtering surgery in white rabbits

Failure of a glaucoma filtering operation mainly results from scarring at the filtering wound, and postoperative proliferation and migration of fibroblasts play an important role histologically in the formation of scar tissue. As an inhibitory agent for fibroblast proliferation, gamma-interferon has been introduced, and the application of gamma-interferon following filtering surgery is now being made on a trial basis. We studied the effect of gamma-interferon histologically on the fibroblast proliferation and collagen synthesis occurring at the filtering site by comparing the effect of gamma-interferon on the experimental group with that of 5-fluorouracil on the control group, using 10 rabbits (20 eyes) after posterior lip sclerectomy. Both groups showed similar flat and diffused bleb grossly and also showed a similar inhibitory effect on fibroblast proliferation and collagen fiber synthesis histologically. Our findings seem to justify the clinical use of gamma-interferon. Further studies on adequate dosage, method of administration, and local and systemic complications would be desired.