Qingfei oral liquid downregulates TRPV1 expression to reduce airway inflammation and mucus hypersecretion injury caused by respiratory syncytial virus infection and asthma in mice

Xiao-Ping Jing, Wu-Ning Yan, Wei-Wei Cheng, Hai-Rong Zeng

Qingfei oral liquid downregulates TRPV1 expression to reduce airway inflammation and mucus hypersecretion injury caused by respiratory syncytial virus infection and asthma in mice

Xiao-Ping Jing1*, Wu-Ning Yan1, Wei-Wei Cheng1, Hai-Rong Zeng1

1Department of Traditional Chinese Medicine, Shanghai Children’s Hospital, Shanghai Jiao Tong University, Shanghai 200062, China.

: Qingfei oral liquid (QF), an experimental Chinese medicine prescription developed from the ancient priscription of traditional Chinese medicines Ma Xin Shi Gan decoction and Tingli Dazao Xie Fei decoction, has been effectively used since decades to treat patients with viral pneumonia and asthma. In our previous study, we had demonstrated that QF can significantly reduce airway hyperresponsiveness, hyperemia, lung tissue edema, inflammatory lung tissue infiltration in mice, airway mucus secretion, and peripheral airway collagen hyperplasia; however, its mechanism of action is unknown.: Fifty6–8-week-old male BALB/c mice were equally and randomly divided into five groups: the control, ovalbumin (OVA), OVA + respiratory syncytial virus (RSV), QF, and dexamethasone (Dxms) groups. The QF group was administered QF at 1.17 g·kg−1·d−1, the Dxms group received dexamethasone injections at 0.2 mg·kg−1·d−1, and the remaining groups were administered PBS. Inflammation in the lung tissue was assessed by hematoxylin and eosin (HE), periodic acid–Schiff (PAS), and Van Gieson staining. ELISA was used to evaluate the IL-13, IL-25, and IL-33 in the mice. Western blotting was used to examine changes in the proteins levels of transient receptor potential vanilloid-1 (TRPV1) and mucin 5AC (MUC5AC) in the lung tissues of mice.: Histopathological evaluation revealed that the OVA and OVA + RSV groups exhibited lung tissue edema and inflammatory lung tissue infiltration in the HE staining and airway secretions in the PAS staining; collagen hyperplasia around the airway was increased in these two groups compared with the control group. The QF group exhibited significantly reduced lung tissue edema, inflammatory lung tissue infiltration, airway secretions, and collagen hyperplasia around the airway compared with the OVA + RSV group. We analyzed the serum levels of IL-13, IL-25, and IL-33 in the mice and found that these levels were higher in the OVA and OVA + RSV groups than in the control group (< 0.05 in the OVA group,< 0.01 in the OVA + RSV group). The QF group exhibited significantly decreased serum levels of IL-13, IL-25, and IL-33 compared with the OVA + RSV group (all< 0.05).The Dxms group also exhibited significant decreases in the serum levels of IL-13 and IL-33 (all< 0.05) but no significant decrease in the serum levels of IL-25 compared with the RSV + OVA group. Finally, we examined the protein levels of TRPV1 and MUC5AC in the lung tissues of mice using Western blotting. After identifying RSV infection in the mice with asthma, the protein levels of TRPV1 and MUC5AC in the lung tissues of mice were significantly higher than those in the control group (< 0.05,< 0.01). We found that compared with RSV + OVA, QF can significantly downregulate the protein level of TRPV1; further, the protein level of MUC5AC was also significantly reduced (all< 0.001).: QF can inhibit RSV replication and reduce airway inflammation and mucus hypersecretion injury caused by RSV infection and asthma, and its mechanism of action may be associated with the downregulation of TRPV1 expression and a decrease in airway mucus hypersecretion injury.

Qingfei oral liquid, Viral pneumonia, Asthma, Respiratory syncytial virus infection, Transient receptor potential vanilloid-1, Mucin 5AC

Qingfei oral liquid (QF), an experimental Chinese medicine prescription developed from the ancient prescriptions of traditional Chinese medicine (TCM) Ma Xin Shi Gan and Tingli Dazao Xie Fei decoctions, can inhibit respiratory syncytial virus replication and reduce airway inflammation and mucus hypersecretion injury caused by respiratory syncytial virus infection and asthma, and its mechanism of action may be associated with the downregulation of transient receptor potential vanilloid-1 expression and a decrease in airway mucus hypersecretion injury.

In children, the finding of an acute asthma attack induced by respiratory syncytial virus infection is in line with the theory of TCM stating that Xiao Zheng (the name of a disease in TCM theory) is caused by exogenous pathogenic factors. The symptoms of Xiao Zheng that recorded in the ancient medical book entitled(),such as dyspnea, throat phlegm, and thick yellow expectoration, is similar to those of asthma. QF is a compound traditional medicine preparation approved by the Jiangsu Province Food and Drug Administration of China (serial no. Z04000512). It was developed from the clinical experience of Shouchuan Wang, a renowned professor of TCM at the Nanjing University of Chinese Medicine and adapted from the ancient prescriptions of Chinese medicine Ma Xin Shi Gan and Tingli Dazao Xie Fei decoctions. Ma Xin Shi Gan decoction comes from the classic Chinese medicine book(); Ting Li Da Zao Xie Fei decoction comes from the well-known Chinese medicine book().

Background

Asthma is a heterogeneous disease characterized by chronic airway inflammation, with recurrent wheeze, cough, dyspnea, and chest tightness as the main clinical manifestations [1]. According to the Global Initiative for Asthma Committee, there are approximately 300 million individuals with asthma worldwide, and the prevalence of asthma in children is still increasing, especially in young children in developing countries [2–4]. The incidence of childhood asthma in China is increasing [5], posing a serious threat to children’s health. Respiratory syncytial virus (RSV), a type of RNA virus belonging to, is one of the most important pathogens of respiratory tract infection in children. RSV infection has a certain correlation with adult-onset asthma [6]. It is also one of the important causes of asthma attacks and aggravation in children [7]. Asthma with RSV infection can destroy the intrinsic barrier of airway mucosa, accumulate several inflammatory factors, and aggravate mucus secretion. It is difficult to clear viral and inflammatory factors adhered to the walls of the lung due to airway mucus hypersecretion, which would form a mucus plug in serious cases of airway blocks, aggravate airway spasm, reduce lung function, and increase mortality in children [8, 9].

In children, the finding of an acute asthma attack induced by RSV infection is in line with the theory of traditional Chinese medicine (TCM) stating that Xiao Zheng (the name of a disease in TCM theory) is caused by exogenous pathogenic factors. The symptoms of Xiao Zheng that recorded in the ancient medical book entitled(),such as dyspnea, throat phlegm, and thick yellow expectoration, is similar to those of asthma. Qingfei oral liquid (QF) is a compound traditional medicine preparation approved by the Jiangsu Province Food and Drug Administration of China (serial no. Z04000512). It was developed from the clinical experience of Shou-Chuan Wang, a renowned professor of TCM at the Nanjing University of Chinese Medicine and adapted from the ancient prescriptions of Chinese medicine Ma Xin Shi Gan decoction (contains Ma Huang (), Xing Ren (), Shi Gao (), Gan Cao ()) and Tingli Dazao Xie Fei decoction (contains Ting Li Zi (), Da Zao ()). Ma Xin Shi Gan decoction comes from the classic Chinese medicine book(); Ting Li Da Zao Xie Fei decoction comes from the well-known Chinese medicine book().

The pathogenesis of airway mucus hypersecretion injury caused by RSV infection in asthma has not been fully elucidated, and the treatment methods are currently limited [10]. Recent research has found that the main molecular basis of airway injury is the activation of transient receptor potential vanilloid-1 (TRPV1) in the lung tissues of patients with asthma and RSV infection, which leads to the opening of Ca2+channels in airway cells and an increase in airway mucus secretion[11, 12]. Since decades, QF has been used to effectively treat patients with viral pneumonia and asthma. Our previous study has demonstrated that QF can significantly reduce airway hyperresponsiveness, hyperemia, lung tissue edema, inflammatory lung tissue infiltration in mice, airway mucus secretion, and peripheral airway collagen hyperplasia; however, its mechanism of action remains unknown [13].

Therefore, the present study aimed to investigate the effects of QF on pathological and inflammatory changes, lung function, inflammatory factors, and protein levels of TRPV1 and mucin 5AC (MUC5AC) and determine their correlation with asthma and RSV infection in the lung tissues of mice based on the findings of previous research to explore the underlying mechanism of action of a TCM compound for treating asthma.

Materials and methods

Drugs and chemicals

QF, a compound preparation of TCM licensed by the Jiangsu Province Food and Drug Administration of China (serial no. Z04000512), was purchased from the Jiangsu Province Hospital of TCM. It comprises Zhi Ma Huang () 3 g, Ku Xing Ren () 10 g, Sheng Shi Gao () 20 g, Huang Qin () 6 g, Sang Bai Pi () 10 g, Ting Li Zi () 10 g, Qian Hu () 10 g, Hu Zhang () 12 g, and Dan Shen () 10 g. All the reagents and solvents used in this study were commercially available and of reagent grade.

Subjects and experiment design

RSV-infected human laryngeal carcinoma cells Hep-2. According to Yan Sun’s protocol [14], the RSV A2 strain was inoculated in Hep-2 cells, which were cultured with the basal medium comprising 10% fetal bovine serum (Gibico, Australia, 2036226) and 1% penicillin-streptomycin (Gibico, USA, 1786396) at 37°C and 5% CO280%–90% confluency with respect to the full visual field was observed. The cell surfaces were washed twice with PBS (HyClone, USA, AB10115027), then RSV was overlaid on it, and the flask was gently shaken every 15–30 min. The unbound RSV was abandoned after 2 h, and the incomplete medium comprising 2% fetal bovine serum and 1% penicillin–streptomycin was added. The cells and supernatant were scraped and harvested in centrifuge tubes, and incidences of syncytia formation, cell death, or floating cells were noted after 3–5 days of incubation under the same condition. The cell pellet was resuspended, and the mixture was rapidly frozen in the refrigerator at −80°C, followed by rapid thawing in a 37°C water bath. This freeze-thaw cycle was repeated thrice and vortexed after every time. The pooled cells and supernatants were centrifuged for 10 min at 300 × g and 4°C and then filtrated at 0.45 μm. The filtrate was equally divided into freezing tubes, which were rapidly frozen in liquid nitrogen and stored at –80°C until further use.

Animals. FiftyBALB/c mice were maintained in an environmentally controlled room, with temperature maintained at 25°C ± 2°C, humidity at 40% ± 5%, and a 12/12-h light/dark cycle. Food and water were supplied. Male BALB/c mice (6–8 weeks old) weighing 20 ± 10 g were purchased from the Shanghai Slack Animal Company of China. This study was approved by the Institutional Animal Care and Use Committee of Shanghai Jiao Tong University (approval no. 2016001).

All the mice were randomly divided into five groups: the control, ovalbumin (OVA), OVA + RSV, QF, and dexamethasone (Dxms) groups (each group had 10 mice). OVA sensitization and challenge procedures were performed as indicated previously with slight modifications [15]. All the mice were sensitized via intraperitoneal injections of 20 μg of OVA (grade V, Sigma) adsorbed onto 2 mg aluminum hydroxide gels (grade V, Sigma) on 0, 14, and 28 days and were challenged for 30 min·d−1from days 22 to 30 via aerosol nebulization with OVA (1% in PBS) using a 402 AI ultrasonic atomizer (Shanghai Yuyue Medical Equipment Co., Ltd.). The control group received intraperitoneal injection of PBS comprising the aluminum hydroxide gel and vehicle (PBS comprising 1% normal mouse serum) inoculation; however, they were not subjected to intranasal challenge. Then the mice in the OVA + RSV, QF, and Dxms groups were further infected with RSV (ATCC). The procedures for viral infection with RSV were modified from the methods described by Sun and performed on the mornings of days 28, 30, and 32 [16]. Then the QF group were treated with QF 1.17 g·kg−1·d−1and the Dxms group was treated with dexamethasone 0.2 mg·kg−1·d−1on the afternoons of days 25, 27, 29, and 31, whereas the control group as well as the OVA and OVA + RSV groups were administered PBS.

After that, the mice were sacrificed via intraperitoneal injections of overdose of ketamine/xylazine, and their serum samples were obtained by extracting blood from their eyeballs on the last experimental day. A portion of the lung tissue was stored in liquid nitrogen for protein analysis, and the remaining portions were fixed in 4% buffered paraformaldehyde for histological examination. These experiments were performed in triplicate.

Histopathological evaluation. Lung tissues were fixed overnight in 4% buffered paraformaldehyde and embedded in paraffin. The paraffin blocks were sliced (Leica, Germany, RM2235) into 4-μm sections, stretched in a water bath at 60℃ (Leica, China, HI1210), removed using glass slides, and transferred onto a slide drier at 42℃ (Leica, China, HI1220) for 30 min. The paraffin sections were deparaffinized by xylene and washed with ethyl alcohol. In hematoxylin and eosin (HE) staining, the sections were stained with Harri’s hematoxylin, differentiated with 1% hydrochloric acid ethanol, and moved into eosin for 5 seconds. Van Gieson (VG) sections were first stained with Weigert’s hematoxylin, differentiated with 1% hydrochloric acid ethanol, moved into VG’s dye for 3 seconds, and differentiated again with 95% alcohol. In periodic acid–Schiff (PAS) reaction, the PAS sections were oxidized in periodic acid, moved into Schiff’s reagent, differentiated with 5% potassium metabisulfite, and counter stained with HE. All the sections were dehydrated with gradient concentration ethyl alcohol from low to high, and transparent and were sealed by neutral resin; they were observed under a light microscope at high magnification (200×) (Leica, Germany, BX42).

ELISA. The serum levels of inflammatory factors IL-13, IL-25, and IL-33 were analyzed using ELISA according to the manufacturer’s instructions (USCN Business Co., Ltd., China). We added 100 μL each of standard and sample dilutions into appropriate wells. We used the plate sealer to cover the samples and incubated them for 2 h at 37°C. We removed the liquid from each well with special attention to avoid washing and added 100 μL of detection reagent. A working solution was added into each well, then incubated for 1 h at 37°C, and covered with the plate sealer to protect the solution from light. Aspirate each well and wash with 1× Wash Buffer by a squirt bottle, repeating the process 2 times for a total of 3 washes, and let Wash Buffer sit for 1 min. Remove the remaining liquid from all wells completely by snapping the plate onto absorbent paper. After the last wash, remove any remaining Wash Buffer by aspirating or decanting. Invert the plate and blot it against clean absorbent paper. We added 100 μL of detection reagent B working solution into each well and allowed it to incubate for 30 min at 37°C. We then added 90 μL of substrate solution into each well and allowed it to incubate for 15 min at 37°C, protecting it from light. Finally, we added 50 μL of stop solution into each well. Optical density was immediately measured at 450 nm using a microtiter plate reader.

Western blotting. Total proteins from the lung tissues of mice were homogenized with the sample buffer (25 mM Tris, pH 6.8, 1% sodium dodecyl sulfate (w/v), 5% mercaptoethanol (v/v), 1 mM ethylenediaminetetraacetic acid, 4% glycerol, and 0.01% bromophenol blue). The proteins were separated by 6% sodium dodecyl sulfate-polyacrylamide gel electrophoresis and transferred to polyvinylidene difluoride membranes (Immobilon-PSQ, Germany, NO. R7KA8928E). The membranes were incubated with the rabbit primary antibody TRPV1 (Proteintech, Wuhan, China, 1:1,000 dilution) and murine primary antibody MUC5AC (GeneTax, CA, USA, 1:200 dilution) for 2 h at 22°C. The membranes were then incubated with horseradish peroxidase-conjugated goat anti-rabbit (Biosharp, China, BL003A, 1:5000) and goat anti-mouse (Biosharp, China, BL001A, 1:5000) secondary antibodies for 2h at 22°C. The signals were visualized and detected with an enhanced chemiluminescence (ECL) system (Thermo Scientific, Waltham, MA, USA, and ClarityTMWestern ECL Substrate, Bio-Rad, USA, 102031247, respectively). The protein bands were analyzed using β-actin as an internal reference.

Statistical analysis

The obtained data were statistically analyzed and presented as mean ± standard deviation (SD). Datasets with three or more groups were analyzed using one-way analysis of variance (ANOVA) or one-way ANOVA with repeated measures, and multiple comparisons were analyzed using least significant difference post-hoc tests. Comparisons between two groups were analyzed using variance analysis.values of < 0.05 were considered statistically significant.

Results

RSV-infected Hep-2 cells

Hep-2 cells that adhered to the walls of the culture plates formed a single layer of cells. Under the light microscope, these cells covered the bottom wall and were arranged regularly and closely; they were inlaid with each other into polygons in the shape of “paving stones.” After the RSV A2 strain infected the cells, typical fusion lesions appeared. Under the microscope, the cell boundary was unclear, and the cells in the lesions fused with each other to form a “multinucleated giant cell” syncytium (Figure 1).

Effects of QF on inflammatory lung tissue infiltration in mice

To demonstrate the inhibitory effects of QF on inflammation in lung tissues, HE staining was performed, which revealed a pulmonary pathology. As shown in Figure 2, significant infiltration of inflammatory cells into the peribronchiolar and perivascular connective tissues was observed in the OVA + RSV group. Conversely, the QF group exhibited remarkably attenuated airway inflammation at the dose of QF. PAS and VG staining were conducted to evaluate the effects of QF on mucus production and collagen deposition in lung tissues. The OVA + RSV group exhibited a marked increase in peribronchial collagen deposition and airway mucus hypersecretion within the bronchi in the lungs. Conversely, the QF group exhibited significantly reduced mucus production and collagen deposition, similar to the observations in the Dxms group (Figure 2).

Effects of QF on the serum levels of cytokines in mice

Airway inflammation in asthma is characterized by an imbalance of IL cytokines such as IL-13, IL-25, and IL-33. Therefore, the serum levels of IL-13, IL-25, and IL-33 in the mice were measured using ELISA to determine whether QF could modulate this imbalance. As shown in Figure 3, we found that the serum levels of cytokines were higher in the OVA and OVA + RSV groups than in the control group (< 0.05 in the OVA group,< 0.01 in the OVA + RSV group). The QF group exhibited significant decreases in the serum levels of IL-13, IL-25, and IL-33 compared with the RSV + OVA group (all< 0.05). The Dxms group also exhibited significant decreases in the serum levels of IL-13 and IL-33 (all< 0.05) but no significant decrease in the serum levels of IL-25 compared with the RSV + OVA group.

Effects of QF on the protein levels of TRPV1 and MUC5AC

It is found that TRPV1 in the airway of children with asthma participates in the regulation of airway inflammation and mucus hypersecretion. Moreover, it can reduce airway inflammatory responses by regulating TRPV1 and MUC5AC, and it plays a certain therapeutic role in asthma. We investigated the effects of QF on the protein levels of TRPV1 and MUC5AC in the lung tissues of mice. As shown in Figure 4, the mice exposed to QF exhibited significantly reduced protein levels of TRPV1 and MUC5AC compared with the mice with RSV infection and asthma (< 0.05,< 0.01). QF apparently blocked this RSV-induced TRPV1 upregulation, and the QF group restored the protein levels of MUC5AC back to normal (all< 0.001).

Discussions

Capsaicin receptor, also known as vanilloid receptor 1, was cloned as capsaicin-activated receptor in 1997 [17]. TRPV comprises six members—TRPV1–TRPV6—which are widely expressed in the mammalian respiratory system [18]. TRPV channels can be activated by various extracellular and intracellular stimuli and would promote calcium influx followed by acceleration of functional regulation in the respiratory system with a pathological state. Research has demonstrated that the analyses of the protein levels of TRPV1 and TRPV2 in the peripheral blood of these levels were one of the risk factors for asthma in children in Beijing, China [19]. The complex crosstalk normal children and children with asthma showed that between the TRPV1 gene and related cytokines leads to an immune disorder or peripheral sensitization, eventually resulting in the occurrence of asthma in children [20].

Figure 1 Respiratory syncytial virus-infected human laryngeal carcinoma cells Hep-2.

Hep-2 cells adhered to the walls of culture plates to form shapes of “paving stones”. After the infection of RSV A2 strain, the cells formed a “multinucleated giant cell” syncytium. CON, control; RSV, respiratory syncytial virus.

Figure 2 Effects of Qingfei oral liquid on the histomorphology of lung tissues.

QF affected inflammatory cells, collagen deposition, and mucus production in lung tissues. From the HE sections of the lung tissue, the pulmonary tissue in the OVA + RSV group exhibited typical interstitial pneumonia, the alveolus cavity was obviously narrowed, inflammatory lung tissue infiltration was obvious, and the capillary was dilated and congested. PAS staining revealed airway mucus secretion, and the OVA + RSV group exhibited the highest level of secretion. The QF group exhibited significantly reduced airway mucus secretion compared with the OVA + RSV group. With respect to VG staining, the QF group exhibited significantly reduced collagen hyperplasia around the airway and interstitial tissue compared with the other groups. CON, control; OVA, ovalbumin; RSV, respiratory syncytial virus; QF, Qingfei oral liquid; Dxms: dexamethasone;HE, hematoxylin and eosin staining; PAS, periodic acid–Schiff staining; VG, Van Gieson staining.

Figure 3 Effects of Qingfei oral liquid on the serum levels of inflammatory factors in mice.

Serum levels of inflammatory factors in mice were evaluated in all the groups using ELISA. Data are presented as mean ± SD values. Serum levels of inflammatory factors in the experiment groups with superscripted symbols are significantly different from those in the control group (a,< 0.05, b,< 0.01). The QF group exhibited significantly different serum levels of inflammatory factors compared with the OVA + RSV group (c,< 0.05) (n = 10). SD, standard deviation; Con, control; OVA, ovalbumin; RSV, respiratory syncytial virus; QF, Qingfei oral liquid;Dxms: dexamethasone.

Figure 4 Effects of Qingfei oral liquid on the protein levels of TRPV1 and MUC5AC in lung tissues.

The protein expressions of TRPV1 and MUC5AC were normalized to that of β-actin. The protein levels in the control group were set to 0. Data are presented as mean ± SD values. The OVA + RSV group exhibited significantly different protein levels of TRPV1 and MUC5AC compared with the control group (a,< 0.05, b,< 0.01). The QF group exhibited significantly different protein levels of TRPV1 and MUC5AC compared with the OVA + RSV group (c,< 0.05, d,< 0.01, e,< 0.001) (n = 3). TRPV1, transient receptor potential vanilloid-1; MUC5AC, mucin 5AC; SD, standard deviation; Con: control; OVA, ovalbumin; RSV, respiratory syncytial virus; QF, Qingfei oral liquid, Dxms: dexamethasone.

TRPV1 is widely distributed and expressed in the respiratory system components, such as smooth muscle cells, epithelial cells, vascular endothelial cells, and mast cells, indicating that it plays an important biological role in lung [21]. As a gated ionic channel with high permeability to Ca2+, which is an important signal transduction molecule in cells, TRPV1 participates in the regulation of the release of airway inflammatory factors and other vital physiological functions as well as the contraction of airway smooth muscle[22]. In recent years, some scholars have confirmed that TCM as a treatment for asthma can reduce the injury due to airway mucus hypersecretion by regulating TRPV1 [23]. A study has demonstrated that a TRPV1 antagonist—capsazepine or TRPV1 siRNA—attenuates airway inflammation and hypersensitivity and reduces the levels of IL-13 (Th2 cytokines), IL-25, and IL-33 (epithelium-derived cytokines) in mice with asthma[22].

In previous studies, our group has researched whether QF can reduce inflammatory reactions in lung tissues, airway mucus hypersecretion, and airway hypersecretion caused by collagen hyperplasia around the airway[13, 24]. To further understand the mechanism of action of QF with regard to airway mucus hypersecretion injury in asthma caused by RSV infection and explore the possible targets of treatment, we performed a proteomic analysis and demonstrate that the protein level of MUC5AC is abnormally high in the lung tissues of mice with asthma and RSV infection and that TRPV1 may play a role in regulating the protein level of MUC5AC through the TRPV1/Ca2+/MUC5AC signaling pathway.

Our previous study has found that QF can significantly reduce the levels of eosinophils in the bronchoalveolar lavage fluid of mice with asthma[13]. Pulmonary function test is the gold standard for determining airway hyperresponsiveness [25]. In our previous research, we used the Buxco RC system to test the pulmonary function of mice, which suggesting that QF satisfactorily reduces airway hyperresponsiveness in mice[13]. Previous studies have demonstrated that baicalin extract from Huang Qin () and resveratrol from Hu Zhang () can reduce airway inflammation and airway hyperresponsiveness in animal models of asthma and RSV infection [25–26], which is consistent with the findings for a single drug of the formula, thus providing an objective basis for demonstrating the effectiveness of the formula. The present study found that QF could improve airway compliance and significantly reduce airway hyperresponsiveness, airway resistance, airway mucus secretion, collagen proliferation around the airway, serum levels of inflammatory factors (IL-13, IL-25, and IL-33), and inflammatory lung tissue infiltration in mice with asthma. QF could obviously downregulate the protein levels of TRPV1 and MUC5AC in the lung tissues of mice, suggesting that QF reduces the high protein levels of MUC5AC in mice with asthma by regulating TRPV1. However, its underlying mechanism of action remains unknown and warrants additional research.

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This work was supported by Natural Science Foundation of China (81674020).

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RSV, respiratory syncytial virus; Dxms, dexamethasone; TCM: traditional Chinese medicine; TRPV1, transient receptor potential vanilloid-1; MUC5AC, mucin 5AC; QF, Qingfei oral liquid; OVA, ovalbumin; Dxms: dexamethasone; SD, standard deviation; HE: hematoxylin and eosin; VG: Van Gieson; PAS: periodic acid–Schiff.

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The authors declare that they have no conflict of interest.

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Xiao-Ping Jing, Wu-Ning Yan, Wei-Wei Cheng, et al. Qingfei oral liquid downregulates TRPV1 expression to reduce airway inflammation and mucus hypersecretion injury caused by respiratory syncytial virus infection and asthma in mice. Traditional Medicine Research 2020, 5 (4): 229–237.

:Nuo-Xi Pi.

:31 December 2019,

25 January 2020,

:3 February 2020.

Xiao-Ping Jing. Department of Traditional Chinese Medicine, Shanghai Children’s Hospital, Shanghai Jiao Tong University, No. 355 Luding Road, Putuo District, Shanghai 200062, China. E-mail: xiaopingjdoctor@126.com.

10.12032/TMR20200128156