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BY 4.0 license Open Access Published by De Gruyter Open Access December 31, 2022

Chinese medicinal plant Polygonum cuspidatum ameliorates silicosis via suppressing the Wnt/β-catenin pathway

  • Yangmin Jia EMAIL logo , Anlong Wang , Libin Liu , Huaichong Wang , Guohui Li and Fengwei Zhang
From the journal Open Chemistry

Abstract

Polygonum cuspidatum (PC) extract has effect on silica-induced pulmonary fibrosis. This study aimed to explore the anti-pulmonary-fibrosis effects and mechanism of PC. Sprague–Dawley rat model was constructed by inhalation of silicon dioxide suspension through tracheal intubation method. And histopathological examination showed that PC inhibited inflammatory cell infiltration, fibrous and collagen hyperplasia, and protected the normal structure of alveoli. TUNEL assay declared that PC retarded cell apoptosis. Meanwhile, up-regulation of basic fibroblast growth factor, plated-derived growth factor, and TNF-α in silicosis rats was decreased by PC addition. In addition, human fetal lung fibroblasts (HFL-1) cells were stimulated with transforming growth factor-β1 (TGF-β1). PC administration increased the proliferation and invasion of TGF-β1-stimulated HFL-1 cells whereas decreased cell apoptosis. Moreover, western blotting exhibited that PC treatment decreased the expression of α-smooth muscle actin, collagen I, and collagen III in silicosis rats and TGF-β1-stimulated HFL-1 cells. Furthermore, the levels of Wnt/β-catenin pathway proteins were up-regulated in silicosis rats and TGF-β1-stimulated HFL-1 cells, which were weakened by PC treatment. Meanwhile, Wnt3a (an activator of Wnt/β-catenin) addition reversed the effect of PC addition. In conclusion, PC prevents silica-induced fibrosis through inhibiting the Wnt/β-catenin pathway.

1 Introduction

Silicosis is a widespread pulmonary diseases, which arises due to over-exposure and inhalation of crystalline silica in long term [1]. Silicosis is also a main occupational respiratory disease that commonly happened in industrial factory [2]. Silica particles, inhaled into human body, cannot be expelled by lung and continuously stimulate macrophages, causing a range of pulmonary damage such as aggravation of inflammatory cells, deposition of collagen, and progression fibrosis [3]. Fibrosis is irreversible and eventually causes the serious damage of lung function [4]. Silicosis brings severe risks to human life and the current effective treatment of silicosis is lung transplantation [5]. Therefore, the understanding of the mechanism and effective treatment of silicosis is urgent.

Due to their wide range of pharmacological effects, traditional Chinese medicines and their extracts or derivatives are widely used in the development of new drugs and in the treatment of various diseases [6,7,8,9]. Polygonum cuspidatum (PC), also known as Reynoutria japonica Houtt., is a traditional Chinese medicinal herb. The dry root and stems of PC could be considered a traditional Chinese medicine (Huzhang) and widely used to invigorate the blood, relive the cough, and disperse the phlegm [10]. PC exerts the pharmacological effects relied on its bioactive components such as emodin, polydatin, and resveratrol [10]. It has been reported that emodin of PC extract alleviates silica-induced pulmonary fibrosis via inhibiting transforming growth factor-β1 (TGF-β1)/Smad3 and NF-κB pathways [11]. Moreover, Yang et al. found that emodin activates Sirt1 signaling pathway to attenuate silica-mediated pulmonary fibrosis [12]. Zeng et al. found that polydatin, which isolated from PC, has anti-oxidative properties and attenuates reactive oxygen species-induced lung fibrosis in asthma mouse model [13]. These findings suggest that PC has therapeutic effect on lung fibrosis.

The Wnt/β-catenin pathway is involved in the development and metabolism of human diseases [14]. The dysregulation of Wnt/β-catenin pathway leads to the occurrence of diverse lung diseases, such as lung cancer and pulmonary fibrosis [15,16]. Zhang et al. found that blocking Wnt/β-catenin pathway reduces silica-induced pulmonary fibrosis in silicosis rats [17]. In addition, the inhibition of Wnt/β-catenin pathway suppresses pulmonary fibrosis in silica-administered mice [18]. These researches suggest the Wnt/β-catenin pathway participates in silica-induced fibrosis. Meanwhile, studies have found that polydatin and resveratrol inhibit the Wnt/β-catenin pathway [19,20]. Therefore, we suspect that the Wnt/β-catenin pathway may be associated with the process of PC against fibrosis.

In this study, we constructed in vitro and in vivo models to explore the pharmacological effects and potential mechanism of PC on pulmonary fibrosis. The workflow is shown in Figure S1. Our finding might provide new sight for silica-induced fibrosis treatment.

2 Methods and materials

2.1 Drug

PC was obtained from the Chinese herbal medicine department of Hangzhou Red Cross Hospital and prepared as a decoction (1 mg/mL) by the Chinese herbal medicine department.

2.2 Animal model construction and drug treatment

Thirty healthy female Sprague–Dawley rats (200–250 g) were purchased from GemPharmatech Co., Ltd. (Nanjing, China). Rats were housed in a controlled room (a cycle of 12 h light/dark) and ad libitum given water and food. Animal procedures were approved by the Hangzhou Red Cross Hospital. Tracheal intubation method was used to construct animal models of silicosis [21]. Silicon dioxide suspension was diluted into 50 mg/mL by normal saline solution, and the content of free silica and particles (<5 μm) were more than 99%. Before the use, 8,000 U/mL penicillin was added into silicon dioxide suspension. After intraperitoneal injection of 2% pentobarbital sodium (40 mg/kg) for anesthesia, the epidural anesthesia catheter with an adapter was inserted into the trachea of rats. The trachea of rat was injected with 1 mL silicon dioxide suspension and 0.25 mL air. Following the injection, the rats were immediately rotated to distribute the injection evenly in the lungs.

When the animal models of silicosis were established, the rats were casually divided into four groups (n = 6): model, low-dose PC, middle-dose PC, and high-dose PC. Normal healthy rats were set as control group (n = 6). Control and model groups were given 1 mL/100 g normal saline. Model rats in low-dose PC, middle-dose PC, and high-dose PC groups were given 3.0, 6.0, and 12.0 mg/kg decoction of PC once daily, respectively [22]. The treatment time of each group ran through the early stage of silicosis. Serum containing drug was prepared for subsequent cell culture. After euthanize with sodium pentobarbital (160 mg/kg) post 40 days, and the lung tissues of each group rats were collected for subsequent experiments.

2.3 Cell culture

Human fetal lung fibroblast (HFL-1) cells were cultured in Dulbecco’s modified eagle medium (Gibco, Carlsbad, CA, USA) at 37°C. TGF-β1 (5 ng/mL) was used to stimulate fibroblast for 24 h. Then, the prepared serum containing drug was added into the medium at low- (5%), middle- (10%), and high-dose (20%) of PC. Finally, HFL-1 cells were cultured with the addition of 20% prepared serum containing drug and pretreated with 100 ng/mL Wnt/β-catenin pathway activator Wnt3a for 30 min.

2.4 Histopathological examination

Paraffin-embedded slices (5-μm thickness) were dewaxed, rehydrated, and stained with hematoxylin and eosin (HE; Beyotime, Shanghai, China) and Sirius Red (Beyotime) to observe the histopathological changes in silicosis fibrosis. Pictures were captured by microscope (Olympus, Tokyo, Japan).

2.5 TUNEL assay

The apoptosis in collected lung tissues was detected using the TUNEL assay. After routinely dewaxing and hydration, the lung tissues slices were digested by 50 μL proteinases K solution for 30 min, incubated with 50 μL TUNEL solution (Beyotime) at 37°C for 1 h, and then stained with DAPI (Beyotime) for 10 min in darkness. The fluorescence microscope (Olympus) was used to analyze the samples.

2.6 Flow cytometry

A flow cytometer (BD Biosciences, CA, USA) was applied to investigate cell apoptosis. After digestion by 0.25% trypsin, cells were collected and centrifugated at 1,500 rpm for 5 min to discard the supernatant. Following centrifugation, the cells were slightly remixed with 200 μL Annexin V-EGFP and 10 μL propidium iodide (Beyotime). The mixture was incubated at 25°C for 20 min and then put into ice box using sliver paper to avoid light.

2.7 CCK-8 assay

Following cultured 24 h, the HFL-1 cells were suspended using fresh complete medium and seeded into 96-well plate (100 μL/well) and incubated at 37°C with 5% CO2 until cells adherent to the wall. The PC treatment was taken for 0, 24, and 48 h after cells adhered to the wall and cell proliferation was detected using the CCK-8 assay kit (Beyotime).

2.8 Transwell assay

Transwell assay was used for cell invasion detection as previously reported [23]. Briefly, cells were resuspended in serum-free medium and inoculated in the upper chamber (pre-coated with Matrigel), and normal medium was added to the lower chamber. After 24 h incubation, cotton swab was used to slightly wiped off the no-invading cells. Invading cells were fixed with formaldehyde for 30 min and stained with 0.1% crystal violet for 20 min. The images were captured from three random regions under a microscope (Olympus).

2.9 Enzyme-linked immunosorbent assay (ELISA)

The IL-1β (Beyotime), TNF-α (Abcam, Cambridge, UK), and IL-6 (Abcam) ELISA kits were used to detect their concentrations in HFL-1 cells. All experimental protocols were carried out in accordance with the manufacturers’ instructions.

2.10 Quantitative real-time PCR (qRT-PCR) analysis

Total RNA of lung tissues and HFL-1 cells was extracted with TRIzol reagent (Invitrogen, CA, USA). qRT-PCR was performed using cycler apparatus of Real-Time System (MX3000P, Agilent Stratagene, California, USA) with SYBR Green PCR Master Mix (Lifeint, Guangzhou, China), and primers are presented in Table S1. The PCR amplification was as follows: initial denaturation 95°C for 3 min, 40 cycles of annealing at 95°C for 12 s, and extension at 62°C for 40 s.

2.11 Western blot analysis

Collected lung tissues and cells were homogenized, and the sample concentration was analyzed by BCA kit. The samples were separated by gel electrophoresis and electrotransferred into membranes. Membranes were pre-soaked in methanol for 3–5 min, sealed with 5% skim milk for 1 h and then incubated with primary antibodies (Table S2) at 4°C for 12 h. After that, membranes were incubated with secondary antibody for 60 min. Subsequently, protein bands were captured in dark room. Relative protein expression was calculated using the optical density of the target protein bands compared to that of GAPDH.

2.12 Statistical analysis

All experimental data were presented as mean ± standard deviation. One-way analysis of variance was used for multiple groups comparison. The P < 0.05 was considered statistically significance.

3 Results

3.1 PC attenuates fibrosis in silicosis rats

Silicosis rat model was established to investigate the pharmacological effects of PC on silica-induced fibrosis. Histopathological examination by HE staining showed that the healthy lung structures had intact alveolar structures and no inflammatory cell aggregation. The model group had disrupted lung structures with intact alveolar collapse, inflammatory cell infiltration, and fibrous hyperplasia. Pathological symptoms in silicosis rat model were alleviated by different concentrations of PC treatment (Figure 1a). Consistent with the HE staining results, Sirius Red staining showed that PC attenuated silica-induced collagen hyperplasia and protected normal alveolar structures (Figure 1b). In addition, cell apoptosis was enhanced in silicosis rats than that in controls. With the addition of PC, cell apoptosis was obviously reduced in silicosis rats, and high doses of PC were the most effective in inhibiting apoptosis (Figure 1c).

Figure 1 
                  PC attenuates fibrosis in silicosis rats. (a) HE staining of lung tissues from silicosis rat model (scale bar = 50 μm). (b) Sirius Red staining of lung tissues from silicosis rat model (scale bar = 50 μm). (c) TUNEL staining of the lung tissues from silicosis rat model (scale bar = 50 μm). (d and e) The expression of b-FGF, PDGF, and tumor necrosis factor α (TNF-α) in lung tissues of silicosis rats was analyzed by RT-qPCR and western blot assays. (f) The expression of α-SMA, collagen I, and collagen III was detected by western blot. The silicosis rat model was established by injecting silicon dioxide suspension through tracheal intubation. After 40-day drug treatment, the mice were sacrificed and the lung tissues were collected. **P < 0.01 vs control, #
                     P < 0.05 and ##
                     P < 0.01 vs model, ^
                     P < 0.05 and ^^
                     P < 0.01 vs low-dose PC.
Figure 1

PC attenuates fibrosis in silicosis rats. (a) HE staining of lung tissues from silicosis rat model (scale bar = 50 μm). (b) Sirius Red staining of lung tissues from silicosis rat model (scale bar = 50 μm). (c) TUNEL staining of the lung tissues from silicosis rat model (scale bar = 50 μm). (d and e) The expression of b-FGF, PDGF, and tumor necrosis factor α (TNF-α) in lung tissues of silicosis rats was analyzed by RT-qPCR and western blot assays. (f) The expression of α-SMA, collagen I, and collagen III was detected by western blot. The silicosis rat model was established by injecting silicon dioxide suspension through tracheal intubation. After 40-day drug treatment, the mice were sacrificed and the lung tissues were collected. **P < 0.01 vs control, # P < 0.05 and ## P < 0.01 vs model, ^ P < 0.05 and ^^ P < 0.01 vs low-dose PC.

Reportedly, basic fibroblast growth factor (b-FGF), plated-derived growth factor (PDGF), and TNF-α promote fibrosis [24,25]. To investigate the anti-pulmonary fibrosis effects of PC, the expression of bFGF, PDGF, and TNF-α in lung tissues was detected. The expression of bFGF, PDGF, and TNF-α was up-regulated in the model group compared to the control group (P < 0.01). These phenomena were reduced in the treatment of middle- and high-dose PC with dose-dependent effect (P < 0.05) (Figure 1d–e). Moreover, activated fibroblasts are characterized by positive expression of α-smooth muscle actin (α-SMA) and excessive deposition of collagen [26]. The levels of α-SMA, collagen I, and collagen III were facilitated in silicosis rats compared with controls, which were weakened by middle- and high-dose PC treatment (P < 0.05) (Figure 1f).

3.2 PC inhibits Wnt/β-catenin pathway activation in silicosis rats

The blockage of Wnt/β-catenin pathway has been reported to inhibit the progression of silica-induced fibrosis [27]. To investigate whether PC exerts its therapeutic effect of silica-induced fibrosis via Wnt/β-catenin pathway, the levels of pathway-related proteins T cell factor 4 (TCF-4), β-catenin, cyclin D1, and E-cadherin were analyzed. Compared to normal mice, the tracheal instillation of silicon dioxide suspension remarkably up-regulated the mRNA and protein levels of TCF-4, β-catenin, cyclin D1, and E-cadherin (P < 0.01). The up-regulation of pathway-related proteins in silicosis rats was reduced by PC addition, and high-dose PC showed the strongest inhibitory effect (P < 0.05) (Figure 2a and b).

Figure 2 
                  PC inhibits the activation of Wnt/β-catenin signaling pathway in silicosis rats. (a) The mRNA expression of TCF-4, β-catenin, cyclin D1, and E-cadherin in lung tissues was analyzed by RT-qPCR. (b) The protein levels of TCF-4, β-catenin, cyclin D1, and E-cadherin in lung tissues were analyzed by western blot. **P < 0.01 vs control, #
                     P < 0.05 and ##
                     P < 0.01 vs model, ^
                     P < 0.05 and ^^
                     P < 0.01 vs low-dose PC.
Figure 2

PC inhibits the activation of Wnt/β-catenin signaling pathway in silicosis rats. (a) The mRNA expression of TCF-4, β-catenin, cyclin D1, and E-cadherin in lung tissues was analyzed by RT-qPCR. (b) The protein levels of TCF-4, β-catenin, cyclin D1, and E-cadherin in lung tissues were analyzed by western blot. **P < 0.01 vs control, # P < 0.05 and ## P < 0.01 vs model, ^ P < 0.05 and ^^ P < 0.01 vs low-dose PC.

3.3 PC suppresses the activation of fibroblasts

To explore the effect of PC on fibroblasts, the proliferation, invasion, and apoptosis were determined in TGF-β1-stimulate HFL-1 cells. Compared with controls, cell proliferation and invasion in the TGF-β1 group was enhanced, while cell apoptosis was reduced (P < 0.01) (Figure 3a–c). In the treatments of PC in middle and high concentration, cell proliferation and invasion were significantly retarded compared to the TGF-β1 or low-dose PC groups; in contrast, cell apoptosis was raised (P < 0.01).

Figure 3 
                  PC suppresses malignant progresses of HFL-1 cells. (a) The proliferation of HFL-1 cells was detected by CCK-8 assay. (b) Cells’ apoptosis was determined by flow cytometry assay. (c) The invasion of HFL-1 cells was detected by Transwell assay (scale bar = 50 μm). HFL-1 cells were stimulated by TGF-β1 for 24 h and then cultured in the medium with different doses of prepared drug containing serum (5, 10, and 20%). **P < 0.01 vs control, ##
                     P < 0.01 vs TGF-β1, ^^
                     P < 0.01 vs low-dose PC.
Figure 3

PC suppresses malignant progresses of HFL-1 cells. (a) The proliferation of HFL-1 cells was detected by CCK-8 assay. (b) Cells’ apoptosis was determined by flow cytometry assay. (c) The invasion of HFL-1 cells was detected by Transwell assay (scale bar = 50 μm). HFL-1 cells were stimulated by TGF-β1 for 24 h and then cultured in the medium with different doses of prepared drug containing serum (5, 10, and 20%). **P < 0.01 vs control, ## P < 0.01 vs TGF-β1, ^^ P < 0.01 vs low-dose PC.

Subsequently, the levels of inflammatory factors IL-1β, TNF-α, and IL-6 were quantified by ELISA. Results showed that the levels of IL-1β, TNF-α, and IL-6 in the TGF-β1 group were higher than those in the control group. However, treatments with middle- and high-dose PC remarkably reduced inflammatory factors levels (P < 0.01) (Figure 4a). Moreover, western blotting showed that TGF-β1 stimulation resulted in a significant up-regulation of α-SMA, collagen I, and collagen III, which was down-regulated by the treatments of middle- or high-dose PC (P < 0.01) (Figure 4b). Consistent with animal experiments, the increased mRNA and protein expression of TCF-4, β-catenin, cyclin D1, and E-cadherin in TGF-β1-stimulated HFL-1 cells were reversed by middle- or high-dose PC addition (P < 0.05) (Figure 4c).

Figure 4 
                  PC reduces fibrosis and Wnt/β-catenin pathway activation in HFL-1 cells. (a) The expression of inflammatory factors IL-1β, TNF-α, and IL-6 was quantified by ELISA. (b) The levels of α-SMA, collagen I, and collagen III in HFL-1 cells were detected by western blot. (c and d) The expression of TCF-4, β-catenin, cyclin D1, and E-cadherin in HFL-1 cells was analyzed by RT-qPCR and western blot assays. The HFL-1 cells were stimulated by TGF-β1 for 24 h and cultured in the medium with different dose of prepared drug containing serum (5, 10, and 20%). **P < 0.01 vs control, #
                     P < 0.05 and ##
                     P < 0.01 vs TGF-β1, ^
                     P < 0.05 and ^^
                     P < 0.01 vs low-dose PC.
Figure 4

PC reduces fibrosis and Wnt/β-catenin pathway activation in HFL-1 cells. (a) The expression of inflammatory factors IL-1β, TNF-α, and IL-6 was quantified by ELISA. (b) The levels of α-SMA, collagen I, and collagen III in HFL-1 cells were detected by western blot. (c and d) The expression of TCF-4, β-catenin, cyclin D1, and E-cadherin in HFL-1 cells was analyzed by RT-qPCR and western blot assays. The HFL-1 cells were stimulated by TGF-β1 for 24 h and cultured in the medium with different dose of prepared drug containing serum (5, 10, and 20%). **P < 0.01 vs control, # P < 0.05 and ## P < 0.01 vs TGF-β1, ^ P < 0.05 and ^^ P < 0.01 vs low-dose PC.

3.4 PC inhibits the activation of fibroblasts by inactivating Wnt/β-catenin pathway

To further investigate that PC could resist the progression of silica-induced fibrosis via regulating Wnt/β-catenin pathway, Wnt/β-catenin pathway activator Wnt3a was used to treat HFL-1 cells. As exhibited in Figure 5a–c, Wnt3a remarkably reversed the negative effects of the proliferation and invasion of HFL-1 cells with PC treatment (P < 0.05) and alleviated the positive effects of PC-induced HFL-1 cell apoptosis (P < 0.01). Moreover, the treatment of PC resulted in a noteworthy down-regulation of α-SMA, collagen I, and collagen III, which were up-regulated by Wnt3a treatment (P < 0.01) (Figure 5d). Furthermore, PC treatment decreased the expression of TCF-4, β-catenin, cyclin D1, and E-cadherin, which were reversed by Wnt3a addition (P < 0.05) (Figure 5e–f).

Figure 5 
                  PC inhibits the activation of fibroblasts through inactivating Wnt/β-catenin signaling pathway. (a) The proliferation of HFL-1 cells was detected by CCK-8 assay. (b) Cells’ apoptosis was determined by flow cytometry assay. (c) The invasion of HFL-1 cells was detected by transwell assay. (d) The expression of α-SMA, collagen I, and collagen III was examined by western blot. (e and f) The levels of TCF-4, β-catenin, cyclin D1, and E-cadherin in HFL-1 cells were detected by RT-qPCR and western blot assays. HFL-1 cells were pre-treated with 100 ng/mL Wnt3a (an activator of Wnt/β-catenin signaling pathway) for 30 min and cultured in the medium containing 20% prepared drug containing serum. **P < 0.01 vs TGF-β1, #
                     P < 0.05 and ##
                     P < 0.01 vs PC.
Figure 5

PC inhibits the activation of fibroblasts through inactivating Wnt/β-catenin signaling pathway. (a) The proliferation of HFL-1 cells was detected by CCK-8 assay. (b) Cells’ apoptosis was determined by flow cytometry assay. (c) The invasion of HFL-1 cells was detected by transwell assay. (d) The expression of α-SMA, collagen I, and collagen III was examined by western blot. (e and f) The levels of TCF-4, β-catenin, cyclin D1, and E-cadherin in HFL-1 cells were detected by RT-qPCR and western blot assays. HFL-1 cells were pre-treated with 100 ng/mL Wnt3a (an activator of Wnt/β-catenin signaling pathway) for 30 min and cultured in the medium containing 20% prepared drug containing serum. **P < 0.01 vs TGF-β1, # P < 0.05 and ## P < 0.01 vs PC.

4 Discussion

Silicosis is a chronic respiratory disease, caused by over-exposure of free silica [28]. Pulmonary fibrosis is the main pathological symptom in silicosis [29]. To date, there is no specific drug for the treatment of silicosis. Fortunately, there have been great advances in the treatment of silicosis with traditional Chinese medicine, such as tanshinone IIA [30], astragaloside IV [29], and dioscin exerts [31]. Previous pharmacological experiments showed that PC could be used for the treatment of lung diseases through its active compounds [32]. In this study, we investigated the effects of a Chinese herbal PC in silica-induced fibrosis and found PC could regulate Wnt/β-catenin pathway to suppress the progression of pulmonary fibrosis.

As a traditional Chinese medicine, more than 67 compounds have been extracted and identified from PC, containing quinones, stilbenes, flavonoids, counmarins, ligans, and others [33]. Previous study has characterized that PC could effectively improve the early pathological damage of silicosis and delay the progress of silicosis fibrosis through inhibiting the expression of collagen and potent pro-fibrotic factors [34]. Here, we found that the treatment with PC in silicosis rat model could alleviate the silica-induced severe symptoms such as aggravation of inflammatory cells, damaged lung structure, deposition of collagen, and progression of fibrosis with a dose-dependent effect.

Various studies suggest that activated fibroblasts play a key role in driving the progression of pulmonary fibrosis. Fibroblasts express high levels of α-SMA, fibronectin, and collagen, which promote wound healing and fibrotic remodeling [35,36,37]. In this study, PC treatment retarded the proliferation and invasion of TGF-β1-stimulated HFL-1 cells. Also, PC treatment inhibited the upregulation of α-SMA, collagen I, and collagen III in silicosis rats and TGF-β1-induced HFL-1 cells. Pulmonary fibrosis is an important process of silicosis, involving the interaction of various pro-fibrosis factors, including bFGF, PDGF, and TNF-α [24]. The expression of bFGF and PDGF was all up-regulated due to the exposure of silicon dioxide in rats or stimulation of TGF-β1 in HFL-1 cells, which were reduced by PC administration. In addition, inhalation of silica particle could not be expelled from lung tissue and eventually cause the release of inflammatory factors [28]. Our data demonstrated that the silica-/TGF-β1-induced up-regulation of inflammatory factors was decreased by PC treatments. Taken together, these results suggested that the PC alleviated silica-induced fibrosis.

Aberrant of Wnt/β-catenin pathway is s typical feature in pulmonary fibrosis, and the blockage of this pathway could suppress the development and progression of lung fibrosis [38]. Also, Dai et al. found that it modulates Th immune response in silicosis, suggesting that Wnt/β-catenin pathway maybe a potential target in silica-induced fibrosis [39]. In this study, the up-regulation of Wnt/β-catenin pathway proteins TCF-4, β-catenin, cyclin D1, and E-cadherin in silicosis rats or TGF-β1-stimulated HFL-1 cells was weakened by PC addition. Wnt3a is an activator of Wnt/β-catenin pathway. The inhibitory effect of PC on cell proliferation and invasion and the apoptosis-promoting effect were reversed after pretreatment with Wnt3a. Meanwhile, the down-regulation of TCF-4, β-catenin, cyclin D1, and E-cadherin induced by PC treatment was reversed by Wnt3a addition. Collectively, these results suggest that PC could suppress the silica-induced pulmonary fibrosis by inhibiting Wnt/β-catenin pathway.

5 Conclusion

To sum up, this study suggests that PC treatment can alleviate silica-induced inflammatory cell aggregation and collagen deposition. Also, PC treatment inhibited the proliferation and invasion of fibroblasts and promoted fibroblasts apoptosis. Importantly, PC alleviates pulmonary fibrosis by inhibiting the Wnt/β-catenin pathway. However, the Wnt/β-catenin pathway may be one of the pathways involved in PC to alleviate pulmonary fibrosis. There may be more pathways involved in PC for silicosis, which needs to be further validated. Our study provides a promising drug for silica-induced fibrosis treatment.

Acknowledgments

Not applicable.

  1. Funding information: This research was supported by the Zhejiang Traditional Chinese Medicine Science and Technology Plan Project [grant number 2012B212].

  2. Author contributions: Y.J. – conceptualization, writing – original draft, funding acquisition; A.W. – writing – original draft, formal analysis; L.L. – formal analysis, data curation; H.W. – investigation, writing – review & editing; G.L. – formal analysis, writing – review & editing; F.Z. – data curation, validation.

  3. Conflict of interest: Authors state no conflict of interest.

  4. Ethical approval: This study was approved by the Hangzhou Red Cross Hospital.

  5. Data availability statement: The datasets analyzed during the current study are available from the corresponding author on reasonable request.

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Received: 2022-10-24
Revised: 2022-12-05
Accepted: 2022-12-06
Published Online: 2022-12-31

© 2022 the author(s), published by De Gruyter

This work is licensed under the Creative Commons Attribution 4.0 International License.

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