Berberine Inhibits Myofibroblast Differentiation in Nasal Polyp-Derived Fibroblasts via the p38 Pathway

Nasal irrigation with licorice extract (Glycyrrhiza glabra) in treating nasal polyps by reducing fibroblast differentiation and extracellular matrix production in TGF-β1-stimulated nasal polyp-derived fibroblasts by inhibiting the MAPK/ERK-1/2 pathway - an in vitro and in clinic study

BACKGROUND

To date, treating nasal polyps (NPs) is still a medical challenge. However, we have developed an innovative therapy using licorice extract (LE: Glycyrrhiza glabra) to treat rhinitis and sinusitis via nasal irrigation and have discovered that it significantly affects treatment of NPs.

HYPOTHESIS/PURPOSE

This study investigated the mechanism of LE on NPs.

STUDY DESIGN

NPs were collected from three patients using tissue biopsies before and 2 weeks after nasal irrigation with licorice for histopathological analysis. Additionally, NPs from two patients were collected, and nasal polyp-derived fibroblasts (NPDF) were isolated and cultured.

METHODS

The TGF-β1-stimulated NPDF model was used to examine the effect of LE on fibroblast differentiation (biomarker: α-SMA), the consequent production of extracellular matrix (ECM; biomarkers: fibronectin, FBN), and the functional signaling pathway.

RESULTS

Immunohistochemistry (IHC) revealed that the number of eosinophils and the expression of α-SMA and interstitial collagen of polyps after licorice treatment significantly decreased. Additionally, RT-PCR, western blotting, and immunofluorescence (IF) showed that α-SMA and FBN expressions were significantly increased in the NPDF, which was stimulated by TGF-β1, and LE dose-dependently could effectively reduce this effect. Furthermore, western blotting showed that LE could attenuate α-SMA and FBN expressions by preventing the signaling pathway of MAPK/ERK-1/2, which IHC and IF further confirmed. In addition, LE effectively suppressed the cell migration of NPDF, which is related to polyp expansion.

CONCLUSION

LE is clinically used to treat sinusitis with NPs through nasal irrigation, which significantly reduces the size of NPs. This effect could attenuate fibroblast differentiation, ECM production and cell migration, and one of the functional mechanisms may be through inhibition of the MAPK/ERK-1/2 signaling pathway.

TRIAL REGISTRATION

ISRCTN (No. 51425529) registered on 17/04/2020 (retrospectively registered) - http://www.isrctn.com/ISRCTN51425529.

SB203580-A Potent p38 MAPK Inhibitor Reduces the Profibrotic Bronchial Fibroblasts Transition Associated with Asthma

Subepithelial fibrosis is a component of the remodeling observed in the bronchial wall of patients diagnosed with asthma. In this process, human bronchial fibroblasts (HBFs) drive the fibroblast-to-myofibroblast transition (FMT) in response to transforming growth factor-β₁ (TGF-β₁), which activates the canonical Smad-dependent signaling. However, the pleiotropic properties of TGF-β₁ also promote the activation of non-canonical signaling pathways which can affect the FMT. In this study we investigated the effect of p38 mitogen-activated protein kinase (MAPK) inhibition by SB203580 on the FMT potential of HBFs derived from asthmatic patients using immunocytofluorescence, real-time PCR and Western blotting methods. Our results demonstrate for the first time the strong effect of p38 MAPK inhibition on the TGF-β₁-induced FMT potential throughout the strong attenuation of myofibroblast-related markers: α-smooth muscle actin (α-SMA), collagen I, fibronectin and connexin 43 in HBFs. We suggest the pleiotropic mechanism of SB203580 on FMT impairment in HBF populations by the diminishing of TGF-β/Smad signaling activation and disturbances in the actin cytoskeleton architecture along with the maturation of focal adhesion sites. These observations justify future research on the role of p38 kinase in FMT efficiency and bronchial wall remodeling in asthma.

Effect of astragalus injection on renal tubular epithelial transdifferentiation in type 2 diabetic mice

Background

Astragalus injection is used by practitioners of traditional Chinese medicine to treat diabetic nephropathy (DN). The current study was conducted to determine the effect of astragalus on tubular epithelial transdifferentiation during the progression of DN in KKAy mice, as well as to investigate the molecular mechanism underlying this effect.

Methods

Diabetic, 14-week-old, male KKAy mice were randomly divided into a model group and an astragalus treatment group, while age-matched male C57BL/6 J mice were selected as controls. The treatment group received daily intraperitoneal injections of astragalus (0.03 mL/10 g per day), while the model group received injections of an equal volume of saline. Mice were euthanized after 24 weeks. Serum samples were obtained from the animals in each group for blood glucose measurement. Kidney tissue samples were used for morphometric studies. The mRNA and protein expression levels of transforming growth factor beta 1 (TGF-β1), transforming growth factor beta receptor 1 (TGFβ-R1), alpha smooth muscle actin (α-SMA), and E-cadherin were evaluated using real-time polymerase chain reaction (PCR) and western blotting.

Results

Astragalus significantly reduced blood glucose levels; inhibited morphological changes in the kidneys of KKAy mice; reduced mRNA and protein expression levels of TGF-β1, TGFβ-R1, and α-SMA; and increased E-cadherin expression.

Conclusions

Tubular epithelial transdifferentiation plays an important role in the development of DN in diabetic mice. Administration of astragalus likely prevents or mitigates DN by suppressing tubular epithelial transdifferentiation, protecting KKAy mice from renal damage.

Epigallocatechin-3-gallate inhibits collagen production of nasal polyp-derived fibroblasts

Nasal polyps are chronic inflammatory conditions characterized by myofibroblast differentiation and extracelluar matrix accumulation. The major catechin from green tea is (-)-epigallocatechin-3-gallate (EGCG), which has garnered attention for its potential to prevent oxidative stress-related diseases. The purpose of this study was twofold: (i) to determine the effect of EGCG on fibroblast differentiation into myofibroblasts and extracellular matrix accumulation in transforming growth factor (TGF)-β1-induced nasal polyp-derived fibroblasts (NPDFs) and (ii) to determine if the antioxidative effect of EGCG on reactive oxygen species (ROS) production in TGF-β1-induced NPDFs is involved in the aforementioned processes. TGF-β1-induced NPDFs were treated with or without EGCG. α-smooth muscle actin (α-SMA) and collagen type I mRNA were analyzed by reverse transcription-polymerase chain reaction. α-SMA protein was also detected using immunofluorescent staining. The amount of total soluble collagen was analyzed by Sircol collagen assay. ROS activity was measured by the nitroblue tetrazolium reduction assay and visualized by fluorescent microscopy. EGCG significantly inhibited expressions of α-SMA and collagen type I mRNA and reduced α-SMA and collagen protein levels at concentrations of 10-20 µg/mL. EGCG also inhibited TGF-β1-induced ROS production at the same concentrations. These results suggest the possibility that EGCG may be effective at inhibiting the development of nasal polyps through an anti-oxidant effect.