Nuclear respiratory factor-1 negatively regulates TGF-β1 and attenuates pulmonary fibrosis

Leech extract alleviates idiopathic pulmonary fibrosis by TGF-β1/Smad3 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Leech, as a traditional Chinese medicine for the treatment of blood circulation and blood stasis, was also widely used to cure pulmonary fibrosis in China. In clinical practice, some traditional Chinese medicine preparation such as Shui Zhi Xuan Bi Hua Xian Tang and Shui Zhi Tong Luo Capsule composed of leech, could improve the clinical symptoms and pulmonary function in patients with idiopathic pulmonary fibrosis (IPF). However, the material basis of the leech in the treatment of IPF were not yet clear.

AIM OF THE STUDY

Screen out the components of leech that have the anti-pulmonary fibrosis effects, and further explore the therapeutic mechanism of the active components.

MATERIALS AND METHODS

In this study, the different molecular weight components of leech extract samples were prepared using the semi-permeable membranes with different pore sizes. The therapeutic effects of the leech extract groups with molecular weight greater than 10 KDa (>10 KDa group), between 3 KDa and 10 KDa (3-10 KDa group), and less than 3 KDa (<3 KDa group) on pulmonary fibrosis were firstly investigated by cell proliferation and cytotoxicity assay (MTT), cell wound healing assay, immunofluorescence staining (IF) and Western blot (WB) assay through the TGF-β1-induced fibroblast cell model. Then bleomycin-induced pulmonary fibrosis (BML-induced PF) mouse model was constructed to investigate the pharmacological activities of the active component group of leech extract in vivo. Pathological changes of the mouse lung were observed by hematoxylin-eosin staining (H&E) and Masson's trichrome staining (Masson). The hydroxyproline (HYP) content of lung tissues was quantified by HYP detection kit. The levels of extracellular matrix-related fibronectin (FN) and collagen type Ⅰ (Collagen Ⅰ), pyruvate kinase M2 (PKM2) monomer and Smad7 protein were determined via WB method. PKM2 and Smad7 protein were further characterized by IF assays.

RESULTS

Using TGF-β1-induced HFL1 cell line as a PF cell model, the in vitro results demonstrated that the >10 KDa group could significantly inhibited the cell proliferation and migration, downregulated the expression level of cytoskeletal protein vimentin and α-smooth muscle actin (α-SMA), and reduced the deposition of FN and Collagen Ⅰ. In the BML-induced PF mouse model, the >10 KDa group significantly reduced the content of HYP, downregulated the expression levels of FN and Collagen Ⅰ in lung tissues, and delayed the pathological changes of lung tissue structure. The results of WB and IF assays further indicated that the >10 KDa group could up-regulate the expression level of PKM2 monomer and Smad7 protein in the cellular level, thereby delaying the progression of pulmonary fibrosis.

CONCLUSIONS

Our study revealed that the >10 KDa group was the main material basis of the leech extract that inhibited pulmonary fibrosis through TGF-β1/Smad3 signaling pathway.

Vaporization of perfluorocarbon attenuates sea-water-drowning-induced acute lung injury by deactivating the NLRP3 inflammasomes in canines

Seawater-drowning-induced acute lung injury (SD-ALI) is a life-threatening disorder characterized by increased alveolar-capillary permeability, an excessive inflammatory response, and refractory hypoxemia. Perfluorocarbons (PFCs) are biocompatible compounds that are chemically and biologically inert and lack toxicity as oxygen carriers, which could reduce lung injury in vitro and in vivo. The aim of our study was to explore whether the vaporization of PFCs could reduce the severity of SD-ALI in canines and investigate the underlying mechanisms. Eighteen beagle dogs were randomly divided into three groups: the seawater drowning (SW), perfluorocarbon (PFC), and control groups. The dogs in the SW group were intratracheally administered seawater to establish the animal model. The dogs in the PFC group were treated with vaporized PFCs. Probe-based confocal laser endomicroscopy (pCLE) was performed at 3 h. The blood gas, volume air index (VAI), pathological changes, and wet-to-dry (W/D) lung tissue ratios were assessed. The expression of heme oxygenase-1 (HO-1), nuclear respiratory factor-1 (NRF1), and NOD-like receptor family pyrin domain containing-3 (NLRP3) inflammasomes was determined by means of quantitative real-time polymerase chain reaction (qRT-PCR) and immunological histological chemistry. The SW group showed higher lung injury scores and W/D ratios, and lower VAI compared to the control group, and treatment with PFCs could reverse the change of lung injury score, W/D ratio and VAI. PFCs deactivated NLRP3 inflammasomes and reduced the release of caspase-1, interleukin-1β (IL-1β), and interleukin-18 (IL-18) by enhancing the expression of HO-1 and NRF1. Our results suggest that the vaporization of PFCs could attenuate SD-ALI by deactivating NLRP3 inflammasomes via the HO-1/NRF1 pathway.

O-GlcNAc regulates anti-fibrotic genes in lung fibroblasts through EZH2

Epigenetic modifications are involved in fibrotic diseases, such as idiopathic pulmonary fibrosis (IPF), and contribute to the silencing of anti-fibrotic genes. H3K27me3, a key repressive histone mark, is catalysed by the methyltransferase enhancer of Zeste homologue 2 (EZH2), which is regulated by the post-translational modification, O-linked N-Acetylglucosamine (O-GlcNAc). In this study, we explored the effects of O-GlcNAc and EZH2 on the expression of antifibrotic genes, cyclooxygenase-2 (Cox2) and Heme Oxygenase (Homx1). The expression of Cox2 and Hmox1 was examined in primary IPF or non-IPF lung fibroblasts with or without EZH2 inhibitor EZP6438, O-GlcNAc transferase (OGT) inhibitor (OSMI-1) or O-GlcNAcase (OGA) inhibitor (thiamet G). Non-IPF cells were also subjected to TGF-β1 with or without OGT inhibition. The reduced expression of Cox2 and Hmox1 in IPF lung fibroblasts is restored by OGT inhibition. In non-IPF fibroblasts, TGF-β1 treatment reduces Cox2 and Hmox1 expression, which was restored by OGT inhibition. ChIP assays demonstrated that the association of H3K27me3 is reduced at the Cox2 and Hmox1 promoter regions following OGT or EZH2 inhibition. EZH2 levels and stability were decreased by reducing O-GlcNAc. Our study provided a novel mechanism of O-GlcNAc modification in regulating anti-fibrotic genes in lung fibroblasts and in the pathogenesis of IPF.

Distinct epicardial gene regulatory programs drive development and regeneration of the zebrafish heart

Unlike the adult mammalian heart, which has limited regenerative capacity, the zebrafish heart fully regenerates following injury. Reactivation of cardiac developmental programs is considered key to successfully regenerating the heart, yet the regulation underlying the response to injury remains elusive. Here, we compared the transcriptome and epigenome of the developing and regenerating zebrafish epicardia. We identified epicardial enhancer elements with specific activity during development or during adult heart regeneration. By generating gene regulatory networks associated with epicardial development and regeneration, we inferred genetic programs driving each of these processes, which were largely distinct. Loss of Hif1ab, Nrf1, Tbx2b, and Zbtb7a, central regulators of the regenerating epicardial network, in injured hearts resulted in elevated epicardial cell numbers infiltrating the wound and excess fibrosis after cryoinjury. Our work identifies differences between the regulatory blueprint deployed during epicardial development and regeneration, underlining that heart regeneration goes beyond the reactivation of developmental programs.

Elamipretide(SS-31) Attenuates Idiopathic Pulmonary Fibrosis by Inhibiting the Nrf2-Dependent NLRP3 Inflammasome in Macrophages

Idiopathic pulmonary fibrosis (IPF) is a progressive fatal lung disease with a limited therapeutic strategy. Mitochondrial oxidative stress in macrophages is directly linked to IPF. Elamipretide(SS-31) is a mitochondrion-targeted peptide that has been shown to be safe and beneficial for multiple diseases. However, whether SS-31 alleviates IPF is unclear. In the present study, we used a bleomycin (BLM)-induced mouse model followed by SS-31 injection every other day to investigate its role in IPF and explore the possible mechanism. Our results showed that SS-31 treatment significantly suppressed BLM-induced pulmonary fibrosis and inflammation, with improved histological change, and decreased extracellular matrix deposition and inflammatory cytokines release. Impressively, the expression percentage of IL-1β and IL-18 was downregulated to lower than half with SS-31 treatment. Mechanistically, SS-31 inhibited IL-33- or lipopolysaccharide(LPS)/IL-4-induced production of IL-1β and IL-18 in macrophages by suppressing NOD-like receptor thermal protein domain associated protein 3(NLRP3) inflammasome activation. Nuclear factor erythroid 2-related factor 2(Nrf2) was dramatically upregulated along with improved mitochondrial function after SS-31 treatment in activated macrophages and BLM-induced mice. Conversely, there was no significant change after SS-31 treatment in Nrf2-/- mice and macrophages. These findings indicated that SS-31 protected against pulmonary fibrosis and inflammation by inhibiting the Nrf2-mediated NLRP3 inflammasome in macrophages. Our data provide initial evidence for the therapeutic efficacy of SS-31 in IPF.

Ceapin-A7 potentiates lipopolysaccharide-induced endothelial injury

Barrier dysfunction is the hallmark of severe lung injury, including acute respiratory distress syndrome. Efficient medical countermeasures to counteract endothelial hyperpermeability do not exist, hence the mortality rates of disorders related to barrier abnormalities are unacceptable high. The unfolded protein response is a highly conserved mechanism, which aims to support the cells against endoplasmic reticulum stress, and ATF6 is a protein sensor that triggers its activation. In the current study, we investigate the effects of ATF6 suppression in LPS-induced endothelial inflammation. Our observations suggest that Ceapin-A7, which is an ATF6 suppressor, potentiates LPS-induced STAT3 and JAK2 activation. Hence ATF6 activation may serve as a new therapeutic possibility toward diseases related to barrier dysfunction.

Natural plant resource flavonoids as potential therapeutic drugs for pulmonary fibrosis

Pulmonary fibrosis is an enduring and advancing pulmonary interstitial disease caused by multiple factors that ultimately lead to structural changes in normal lung tissue. Currently, pulmonary fibrosis is a global disease with a high degree of heterogeneity and mortality rate. Nitidine and pirfenidone have been approved for treating pulmonary fibrosis, and the quest for effective therapeutic drugs remains unabated. In recent years, the anti-pulmonary fibrosis properties of natural flavonoids have garnered heightened attention, although further research is needed. In this paper, the resources, structural characteristics, anti-pulmonary fibrosis properties and mechanisms of natural flavonoids were reviewed. We hope to provide potential opportunities for the application of flavonoids in the fight against pulmonary fibrosis.

Prevention of bleomycin-induced pulmonary fibrosis by a RANKL peptide in mice

Despite the recent therapeutic developments for the treatment of pulmonary fibrosis, its prognosis is still not well controlled, and a novel therapeutic agent is needed. Recently, the critical role of Toll-like receptors (TLRs) in the pathophysiology of pulmonary fibrosis has been reported; however, the effects of multiple TLR signaling inhibition are still unknown. Here, we examined how the inhibition of multiple TLRs affects pulmonary fibrosis using a novel synthetic receptor activator of nuclear factor κB ligand (RANKL) partial peptide, MHP1-AcN, which could suppress TLR2, 3, 4, 7, and 9 signaling through CD14 and RANK. When MHP1-AcN was administered in the bleomycin-induced lung fibrosis model, reduced collagen deposition was observed, with suppressed fibrosis-related gene expression including Col1a1, Col1a2, Acta2, Tgfb1 and Tgfbr2. MHP1-AcN also decreased proinflammatory M1 and profibrotic M2 macrophage marker expression. Furthermore, MHP1-AcN treatment inhibited transforming growth factor (TGF-β)-induced Smad2/3 phosphorylation and myofibroblast differentiation in human fetal lung fibroblast (MRC-5) cells. This effect was associated with decreased TGF-β receptor levels and the upregulated Bmp7 and Smad7 expression. These findings suggest that MHP1-AcN protects mice against bleomycin-induced pulmonary fibrosis. MHP1-AcN might provide a novel therapeutic strategy for the pulmonary fibrosis.