Protective effect of adiponectin on paraquat-induced pulmonary fibrosis in mice

Adiponectin inhibits the activation of lung fibroblasts and pulmonary fibrosis by regulating the nuclear factor kappa B (NF-κB) pathway

Idiopathic pulmonary fibrosis (IPF) is a common pulmonary interstitial disease with a high mortality rate. Adiponectin (APN) is reportedly an effective therapy for fibrosis-related diseases. This study aimed to investigate the potential effects of APN on IPF. Male BALB/c mice were injected with bleomycin (BLM) and treated with different doses of APN (0.1, 0.25, and 0.5 mg/kg). The body weights of the mice were recorded. Immunohistochemical, hematoxylin and eosin, and Masson staining were performed to evaluate pulmonary histopathological changes. Enzyme-linked immunosorbent assay (ELISA) and western blotting were performed to assess tissue inflammation. The human lung fibroblasts HELF were stimulated with TGF-β1 and treated with different doses of APN (2.5, 5, and 10 μg/ml). Cell proliferation, inflammation, and fibrosis were determined by MTT assay, EdU assay, colony formation assay, ELISA, and western blotting. APN significantly attenuated BLM-induced body weight loss, alveolar destruction, and collagen fiber accumulation in mice (p < 0.05). APN decreased the expression of α-SMA and collagen I and reduced the concentration of TNF-α, IL-6, IL-1β, and IL-18 in lung tissues (p < 0.05). In TGF-β1-treated HELF cells, cell proliferation and colony formation were inhibited by APN (p < 0.05). Additionally, the expression of α-SMA, collagen I, and pro-inflammatory cytokines were suppressed by APN (p < 0.05). APN inhibited the phosphorylation of IκB and nuclear translocation of p65. In conclusion, these findings suggest that APN is an effective agent for controlling IPF progression. The antifibrotic effects of APN might be mediated via inhibiting the NF-κB signaling pathway.

Diosmin ameliorative effects on oxidative stress and fibrosis in paraquat-induced lung injury in mice

Paraquat (PQ) induces pulmonary fibrosis, a progressive lung disorder resulting in severe respiratory failure and death. Increased oxidative stress, inflammatory reactions, and multiple fibrotic lesions are major features of PQ-induced lung injury. Diosmin (Dio) is a safe drug that is available for clinical use for vascular disorders. Dio exhibits antioxidant, anti-inflammatory, and antifibrotic activities. Accordingly, the aim of this study was to evaluate the protective effect of diosmin on PQ-induced lung injury in mice and the underlying mechanisms involved. Lung injury was induced by PQ (30 mg/kg, intraperitoneally) in NMRI albino mice and Dio (50 and 100 mg/kg, gavage) was administrated 3 days before PQ and continued for 10 or 24 days. After euthanizing the mice, the biochemical and histopathological markers of lung tissue were determined. PQ significantly increased oxidative stress, inflammatory, and fibrotic markers. PQ increased the level of malonedaldehyde (MDA) and hydroxyproline (HYP) and decreased the level of glutathione (GSH) and catalase activity in the lung. Dio (50 and 100 mg/kg) significantly increased GSH levels and catalase activity and decreased HYP content and MDA levels. In addition, Dio reduced histopathological injuries in hematoxylin and eosin-stained and Masson's trichrome-stained sections. These findings suggest that Dio has protective effects against PQ-induced lung injury, which may be due to its antioxidant, anti-inflammatory, and antifibrotic effects.

Bleomycin Inhibits Proliferation via Schlafen-Mediated Cell Cycle Arrest in Mouse Alveolar Epithelial Cells

Background

Idiopathic pulmonary fibrosis involves irreversible alveolar destruction. Although alveolar epithelial type II cells are key functional participants within the lung parenchyma, how epithelial cells are affected upon bleomycin (BLM) exposure remains unknown. In this study, we determined whether BLM could induce cell cycle arrest via regulation of Schlafen (SLFN) family genes, a group of cell cycle regulators known to mediate growth-inhibitory responses and apoptosis in alveolar epithelial type II cells.

Methods

Mouse AE II cell line MLE-12 were exposed to 1–10 µg/mL BLM and 0.01–100 µM baicalein (Bai), a G1/G2 cell cycle inhibitor, for 24 hours. Cell viability and levels of pro-inflammatory cytokines were analyzed by MTT and enzyme-linked immunosorbent assay, respectively. Apoptosis-related gene expression was evaluated by quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR). Cellular morphology was determined after DAPI and Hoechst 33258 staining. To verify cell cycle arrest, propidium iodide (PI) staining was performed for MLE-12 after exposure to BLM.

Results

BLM decreased the proliferation of MLE-12 cells. However, it significantly increased expression levels of interleukin 6, tumor necrosis factor α, and transforming growth factor β1. Based on Hoechst 33258 staining, BLM induced condensation of nuclear and fragmentation. Based on DAPI and PI staining, BLM significantly increased the size of nuclei and induced G2/M phase cell cycle arrest. Results of qRT-PCR analysis revealed that BLM increased mRNA levels of BAX but decreased those of Bcl2. In addition, BLM/Bai increased mRNA levels of p53, p21, SLFN1, 2, 4 of Schlafen family.

Conclusion

BLM exposure affects pulmonary epithelial type II cells, resulting in decreased proliferation possibly through apoptotic and cell cycle arrest associated signaling.

Chlorin e6-Mediated Photodynamic Therapy Suppresses P. acnes-Induced Inflammatory Response via NFκB and MAPKs Signaling Pathway

Photodynamic therapy (PDT), consisting of photosensitizer, light, and oxygen has been used for the treatment of various diseases including cancers, microbial infections and skin disorders. In this study, we examined the anti-inflammatory effect of chlorin e6-mediated PDT in P. acnes-infected HaCaT cells using photosensitizer chlorin e6 (Ce6) and halogen light. The live and heat-killed P. acnes triggered an upregulation of inflammatory molecules such as iNOS, NO, and inflammatory cytokine in HaCaT cells and mouse model. Ce6-mediated PDT notably downregulated the expression of these inflammatory molecules in vitro and in vivo. Similarly, chlorin e6-mediated PDT was capable of regulating inflammatory response in both live and heat killed S. epidermidis exposed HaCaT cells. Moreover, phosphorylation of p38, JNK, and ERK were reduced by Ce6-mediated PDT. Ce6-mediated PDT also reduced the phosphorylation of IKKα/β, IĸBα and NFκB p65 in P. acnes-stimulated HaCaT cells. In addition, the dramatic increase in the nuclear translocation of NFκB p65 observed upon stimulation with P. acnes was markedly impaired by Ce6-based PDT. This is the first suggestion that Ce6-mediated PDT suppresses P. acnes-induced inflammation through modulating NFκB and MAPKs signaling pathways.