Antiviral Activity against Respiratory Syncytial Virus of Polysaccharide from Jerusalem Artichoke (<i>Helianthus tuberosus</i> L.)

Wan, Xinhuan; Liu, Zihao; Wang, Yuliang; Yin, Yiming; Cai, Xiaoqing; Gao, Lina; Wang, Qi; Li, Ying; Zhou, Changzheng

doi:https://doi.org/10.1155/2022/1809879

BioMed Research International

On this page

Abstract Introduction Materials and Methods Results Discussion Data Availability Conflicts of Interest Authors’ Contributions Acknowledgments References Copyright Related Articles

Research Article | Open Access

Volume 2022 | Article ID 1809879 | https://doi.org/10.1155/2022/1809879

Antiviral Activity against Respiratory Syncytial Virus of Polysaccharide from Jerusalem Artichoke (Helianthus tuberosus L.)

Xinhuan Wan,¹Zihao Liu,²Yuliang Wang,³Yiming Yin,¹Xiaoqing Cai,¹Lina Gao,¹Qi Wang,¹Ying Li,¹and Changzheng Zhou¹

Academic Editor: Shin-ichi Yokota

Received22 May 2022

Accepted02 Sept 2022

Published20 Sept 2022

Abstract

Jerusalem artichoke (Helianthus tuberosus L.) polysaccharide (JAP) is a chain polysaccharide composed of D-fructose connected by β (1-2) glycosidic bonds, which is a kind of inulin. This study evaluated the anti-respiratory syncytial virus (RSV) activity of JAP in vivo and in vitro. To investigate its antiviral activity, an MTT assay, q-PCR, enzyme-linked immunosorbent assay (ELISA), and lung histological observation were performed. The results showed that JAP showed anti-RSV activity in vitro with a half maximal inhibitory concentration (IC₅₀) of approximately 29.15 μg/mL. In vivo results suggested that JAP could effectively inhibit RSV proliferation in the lungs and improve lung tissue lesions in RSV-infected mice. Additionally, JAP could also reduce the expression of TLR3 and TLR4 in the lungs, increase serum anti-inflammatory factors IL-4 levels, and reduce pro-inflammatory factors TNF-α and TNF-β levels, which may be related to its anti-RSV activity. This study provides a new approach to anti-RSV therapy and enriches the potential applications of JAP.

1. Introduction

Respiratory syncytial virus (RSV), an important RNA virus, belongs to the genus Pneumovirus of the family Paramyxoviridae, which frequently causes lower respiratory tract infections in infants, the elderly, and adults with weakened immunity [1–4]. According to statistics, in 2015, the number of children under 5 years old who suffered from acute lower respiratory tract infection due to RSV was as high as 33.1 million, of which about 3.2 million required hospitalization, and the death toll was as high as 120,000 [2]. In addition, the annual mortality rate due to RSV infection in adults over the age of 65 in the United States is 0.007% [5], and the mortality rate among hospitalizations is 8% [6]. In northern China, RSV infection is more common in winter and spring, while in southern China, it is more common in spring and summer, and RSV-infected patients are prone to repeated infection. It is reported that almost 100% of infants and young children will be infected with RSV at least once, and infected patients are prone to pulmonary diseases such as abnormal lung function and bronchial asthma after recovery [3, 7]. It is demonstrated that there is a strong association between asthma and severe RSV infection in early childhood. Besides, the elderly and immunocompromised individuals often develop severe lower respiratory tract disease after RSV infection.

Although the current RSV infection situation is very serious, due to the complex RSV infection mechanism, the different composition of the infected population, and the safety of its use, there is no safe and effective vaccine approved for marketing. The only drugs approved by the US FDA for the prevention and treatment of RSV infection are palivizumab and ribavirin. Palivizumab is a humanized monoclonal antibody, which is mainly used to prevent RSV infection in children with congenital heart disease and high risk of lung disease and premature, and cannot be used for post-respiratory syncytial virus infection treatment [8]. Moreover, the poor compliance and high cost of palivizumab also make it not the best choice for anti-RSV. Ribavirin, a broad-spectrum antiviral drug with the structure of guanosine analog, is currently the only small-molecule drug approved by the FDA for the treatment of RSV infection, but its efficacy and safety are still controversial [9]. Besides, there are some candidate RSV inhibitors in the clinical research stage, such as Lumicitabine (ALS-8176), Presatovir (GS-5806), PC-786, JNJ-678, and AK-0529. These RSV inhibitor candidates mainly target fusion protein F and RNA polymerase complex L protein, and some of which have completed clinical phase II, are expected to become new drugs for the treatment of RSV infection. However, the RSV fusion protein F inhibitor will appear cross-resistance, so the development of anti-RSV infection drugs still faces great challenges. The discovery of drugs with anti-RSV activity is imminent.

Studies [10, 11] have shown that many natural or chemically synthesized polysaccharides have inhibitory effects on various viruses. The polysaccharide from Laminaria japonica could exert its anti-RSV activity by up-regulating the production of IFN-α mediated by interferon regulatory factor 3 (IRF3) signaling, with an EC₅₀ of 5.27 mg/mL and a therapeutic index (TI) value of 334 against RSV [10]. The polysaccharide component PSP-2B extracted from Prunella vulgaris showed excellent anti-HSV activity, and its IC₅₀ for HSV-1 and HSV-2 was about 69 μg/mL and 49 μg/mL, respectively [11].

Jerusalem artichoke polysaccharide (JAP), a kind of inulin, is a chain polysaccharide composed of D-fructose linked by β (1–2) glycosidic bonds. Studies have shown that JAP has various effects including regulating gastrointestinal function, improving immunity, improving lipid metabolism, promoting mineral absorption, lowering blood lipids, and lowering blood sugar [12–17]. In this study, we evaluated the anti-RSV activity of JAP in vitro and vivo and further explored its potential mechanism of action.

2. Materials and Methods

2.1. Materials and Chemicals

Jerusalem artichoke was collected from Jingbian County, Shaanxi Province (China). Fructose standard was purchased from Shanghai Yuanye Biotechnology Co., Ltd. Other chemical regents are analytical grade and purchased from Sinopharm (Shanghai, China). RPMI 1640 (Biological Industries, Kibbutz Beit Haemek, Israel) containing 10% fetal bovine serum (Biological Industries, Kibbutz Beit Haemek, Israel) and 1% Penicillin-Streptomycin solution (Biosharp®, Anhui, China) was utilized as culture solution for Vero cells. Vero cells were cultured in CO₂ incubator (HF90, Lishen Scientific Instrument Co., Ltd, Shanghai, China) at 37°C with a humidified atmosphere containing 5% CO₂. Respiratory syncytial virus (RSV) and Vero cells were provided by collaborative innovation center of antiviral traditional Chinese medicine, Shandong University of traditional Chinese medicine. RSV was stored in medical cryogenic freezer (Haier, Shandong, China) at -80°C.

2.2. Extraction and Purification of JAP

The collected tubers of Jerusalem artichoke were washed and cut into homogeneous slices, and then extracted in hot water at 70-80°Cfor 1 h to obtain a crude extract containing JAP. The crude extract was sequentially purified by primary lime and then filtered to remove impurities such as peptides, proteins, and colloids. The prepurified extract was further refined, demineralized using cationic and anionic ion exchange resins, and decolorized using activated carbon. Finally, spray drying was performed to obtain JAP dry powder.

2.3. Determination of JAP Content

Total sugars were determined by the phenol-sulfuric acid method [18], and reducing sugars were determined by the 3,5-dinitrosalicylic acid (DNS) method [19]. The JAP content in the extract was the difference between the two.

2.4. Cytotoxicity Assay

To determine whether the inhibition of Vero cell proliferation was due to cytostatic or cytotoxic effects, the cytotoxicity of JAP in vitro was evaluated by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetr-azolium bromide) assay [20]. Briefly, JAP or ribavirin was added to Vero cells and placed in 96-well plates for 48 h, and then 20μL MTT was added to each well and incubated for 4 hours to measure the absorbance of cells in each well at 490 nm by an Epoch 2T microplate reader. The maximum drug concentration at which cell viability was greater than 90% was recorded as TC₀ (drug non-cytotoxic concentration).

Cytopathic rate =1 − cell survival rate

: The OD value of wells containing drug

: The OD value of wells without drug

: The OD value of wells containing cell culture medium only

2.5. Anti-RSV Activity of JAP In Vitro

JAP with the concentration of TC₀ was added into a 96-well plate filled with monolayer Vero and then serially diluted 2-fold with RPMI-1640 containing 2% FBS to obtain 12 samples with different concentrations. 50 μL of RSV with concentrations of 100 TCID50 were then injected into each well, and the blank control group (containing cell culture medium only), cell control group (containing cells), virus control group (containing cells and virus), and ribavirin group were set well. Each sample was assayed in triplicate. The 96-well plate was then placed in the incubator to observe the morphology and lesions of the cells. When 90% of the cells in the virus control group showed lesions, the culture was stopped. 20 μL MTT dye solution and 50 μL RPMI-1640 containing 2% FBS were added into each well after discarding the remaining culture medium in the 96-well plate and placed in a cell incubator for 4 h. 100 μL of DMSO was then added for color development. Finally, measuring the optical density (OD) at 490 nm, the SI (selection index) value and IC₅₀ (50% inhibitory concentration) were calculated by the Reed-Muench formula as follows:

: The cytopathic rate which is more than 50%

: The cytopathic rate which is less than 50%

: The dilution ratio of the drug added to the well which has a cytopathic rate greater than 50%

: The dilution ratio of the drug added to the well which has a cell survival rate greater than 50%

: Initial concentration of drug

2.6. Anti-RSV Activity of JAP In Vivo

2.6.1. Grouping and Dosage Design

Sixty female Balb/c mice were randomly divided into six groups, including the blank control group, RSV model group, ribavirin group (0.1 g/kg), JAP low-dose group (0.5 g/kg), JAP medium-dose group (1.0 g/kg), and JAP high-dose group (2.0 g/kg). Except for the blank control group, mice in the other 5 groups received 50 μL of RSV supernatant via the nasal drip. Two hours later, gavage was started, once a day. Each administration group was given 0.2 mL/20 g liquid medicine by gavage according to the body weight of mice, and the blank group and model group were given the same amount of 0.9% normal saline by gavage. After 5 days of continuous treatment, the administration was stopped. Weigh and record the weight of each mouse every day during the experiments. All the animal experiments were carried out in line with the regulations of the Animal Care and Use Committee at Shandong University of Traditional Chinese Medicine.

2.6.2. Lung Index Inhibition Ratio and Histological Analysis

After 5 days of treatment with JAP, lungs from mice were subsequently dissected and weights to calculate lung index and lung index inhibition ratio. Paraffin sections of lung tissue were prepared and stained with hematoxylin and eosin (HE) stain. The samples were placed under an upright optical microscope (Nikon Eclipse E100, Japan) to obtain optical micrographs. Histopathological changes were described in results. Furthermore, the histological scoring system of lung tissue established in the previous literature (X. H. [21, 22]) was used to score the histopathological changes of lung tissue in this experiment. A final score (scale: 0-26) per mouse was obtained from assessing the quantity and quality of peribronchial and peribronchial inflammatory infiltrates, luminal exudates, perivascular infiltrates, and parenchymal pneumonia.

2.6.3. Quantitative Real-Time Polymerase Chain Reaction (qRT-PCR)

The collected lung tissue was homogenized using a KZ-II homogenizer for RNA extraction to analyze the expression of three target genes RSV, TLR-3, and TLR-4 by qRT-PCR. Total RNA was isolated using Trizol reagent (Servicebio, Hubei, China). Reverse transcription reactions were performed using Servicebio® RT First Strand cDNA Synthesis Kit (Servicebio, Hubei, China) and Bio-Rad CFX. The reaction was incubated at 25°C for 5 minutes, followed by 30 minutes at 42°C, and finally at 85°C for 5 seconds. Analysis results were normalized to GAPDH. CT values were analyzed using the comparative CT (ΔΔCT) method. Specific primers for qRT-PCR are listed in Table 1.

2.6.4. Enzyme-Linked Immunosorbent Assay (ELISA)

The collected blood was centrifuged at 3 000 r/min for 15 min to obtain serum. TNF-α, TNF-β, and IL-4 concentrations were assessed with corresponding ELISA kits (Beijing 4A Biotech Co., Ltd, China) according to the manufacturer’s instructions.

2.7. Statistical Analysis

Data are expressed as the means ± standard deviation (SD). One-way analysis of variance (ANOVA) for multiple groups was performed using GraphPad Prism 5.0 (GraphPad, La Jolla, CA, U.S.A.). A -value of <0.05 was considered statistically significant.

3. Results

3.1. Extraction and Purification of JAP

After extraction and purification, the contents of total sugar and reducing sugar in the extract were measured to be 81.93% and 3.83%, respectively. After calculation, the JAP content in the extract was 78.10, and the yield was 11.73%. The JAP obtained in this assay has high purity with the doses of high related values in use.

3.2. Anti-RSV Activity of JAP In Vitro

The TC₀ of JAP is about 10 mg/mL. According to the values of SI and IC₅₀ index, JAP exhibited a similar inhibitory effect on RSV as ribavirin (Table 2).

3.3. Anti-RSV Activity of JAP In Vivo

3.3.1. Body Weight Analysis

Body weight change of mice (Figure 1) showed that 2 days after RSV infection, all groups (except the blank control group) experienced a significant weight loss. It was also observed that mice in the above groups were accompanied by symptoms such as decreased food intake, decreased activity, and a slight increase in body temperature, indicating that RSV successfully infected those mice.

The weight of mice in the blank group showed a steady increase. After drug treatment, the body weight of mice in ribavirin and each administration group began to recover on the fourth day, and there was no significant difference between the groups (). More importantly, the weight recovery rate of mice in the treatment group was significantly higher than that of the model group. The mice body weight changes suggested that JAP could significantly improve weight loss in mice induced by RSV infection.

3.3.2. Lung Index Inhibition Ratio and Histological Analysis

As shown in Figure 2(a), the lung index of the RSV model group had significantly increased compared to the blank control group, indicating the mice were infected with RSV virus. Meanwhile, ribavirin and JAP treatment greatly reduced the lung index in mice (), suggesting both ribavirin and JAP attenuated RSV-induced lung injury. Moreover, the effect of JAP medium- and high-dose group was better than that in low-dose group, which was comparable to ribavirin from the results of the lung index inhibition rate (Figure 2(b)).

(a)

(b)

Figure 3 shows the histology of lung tissue. Slight inflammatory cell infiltration was occasionally seen in the lung tissue without other obvious abnormalities in blank control group (Figure 3(a)). The lung tissue in RSV model group (Figure 3(b)) was to be found bronchiolar inflammatory exudates, epithelial cell pyknosis (green arrows), inflammatory cell infiltration, alveolar wall thickening (black arrows), and slight hemorrhage in alveolar spaces and eosinophilic coagulation (blue arrows). Mild pathological changes were also observed in lung tissues of both the ribavirin and JAP treatment groups. However, the histological scores of treatment groups shown in Figure 4 are significantly lower than that of the RSV model group, indicating that JAP treatment could effectively alleviate RSV-induced lung injury in mice.

(a)

(b)

(c)

(d)

(e)

(f)

3.3.3. Effects of JAP on mRNA Expression of RSV, TLR3, and TLR4

To further confirm the anti-RSV activity of JAP in mice, the effect of JAP treatment on the RSV levels in lung tissue was evaluated by qRT-PCR. As shown in Figure 5(a), compared with the RSV model group, the mRNA levels of RSV in the lung tissue of the treatment groups were significantly reduced in a dose-dependent manner, confirming that JAP effectively inhibited the proliferation of RSV in the lung tissue and alleviated the RSV-induced lung damage.

(a)

(b)

(c)

Toll-like receptors, also known as pattern recognition receptors, play critical roles in many important biological functions, including the recognition of pathogens and activation of immune cascade signaling pathways. Recognition and binding of PAMPs by specific TLRs activate cellular signaling cascades through MyD88 (myeloid differentiation primary response 88)-dependent and MyD88-independent pathways, thereby inducing various cytokines, and thus induce inflammatory response [23–25]. To further explore the potential mechanism of JAP anti-RSV activity in vivo, the mRNA levels of TLR3 and TLR4 in lung tissue were also assessed by qRT-PCR. RSV infection significantly up-regulated the mRNA levels of TLR3 and TLR4 in lung tissue and stimulated pulmonary inflammatory response as shown in Figures 5(b) and 5(c). Both ribavirin and JAP treatment could decrease TLR3 and TLR4 mRNA levels, thus alleviating the inflammatory damage caused by RSV infection which was consistent with the results of histological analysis.

3.3.4. Effects of JAP on the Levels of Cytokines in Serum

The serum levels of pro-inflammatory factor TNF-α, TNF-β, and anti-inflammatory factor IL-4 were detected by ELISA to further explore the anti-RSV mechanism of JAP. As shown in Figure 6, the levels of TNF-α and TNF-β were significantly decreased in the middle- and high-dose groups after 5 days of JAP treatment (). However, the content of IL-4 in serum was only significantly increased in the high-dose JAP group (), which might be related to the dose. It is concluded that JAP might regulate the level of cytokines by inhibiting the levels of TLR3 and TLR4, thereby intervening in the inflammatory response process of infected mice.

(a)

(b)

(c)

4. Discussion

RSV is the main cause of lower respiratory tract infection in infants, the elderly, and the immunocompromised. Furthermore, severe respiratory disease induced by RSV infection is associated with an increased risk of long-term wheezing and later asthma [26]. Although RSV vaccines have been developed for more than 50 years, there are still no vaccines approved for marketing. Currently, there are no vaccines and effective therapeutic drugs for the prevention or treatment of RSV infection in clinical practice.

JAP is an inulin-type polysaccharide extracted from Jerusalem artichoke, which has the functions of regulating gastrointestinal function, improving immunity, improving lipid metabolism, promoting mineral absorption, lowering blood lipids, and lowering blood sugar [12–17]. Importantly, many studies have confirmed that polysaccharides also have antiviral activity [10, 11, 27–29]. The effect of JAP on RSV has not been previously reported. Here, we isolated JAP from Jerusalem artichoke and evaluated its antiviral activity against RSV in vitro. It was demonstrated that JAP had an anti-RSV SI of 68.27, showing an anti-RSV level comparable to that of ribavirin. Additionally, we also assessed the anti-RSV effect of JAP in vivo. The results suggested that JAP not only significantly improved the weight loss of RSV-infected mice in a dose-dependent manner (Figure 1) but also effectively attenuated RSV-induced lung injury in mice (Figures 2 and 3). More importantly, JAP significantly reduced the level of RSV mRNA, indicating that JAP inhibited the proliferation of RSV in lung tissue.

TLRs are known as the first line of defense against invading pathogens by recognizing and triggering a suitable response against pathogenic attacks, which play an integral role in inflammation, immune cell regulation, survival, and proliferation [24]. A total of 11 TLRs have been found in humans so far. Among them, TLR4 mainly recognizes the LPS component of Gram-negative bacteria and the fusion protein of RSV, and TLR3 mainly recognizes dsRNA produced during virus replication. Studies have shown that both TLR4 and TLR3 pathways are involved in RSV-induced airway epithelial cellular inflammatory response [30, 31]. Overexpression of inflammatory cytokines such as TNF-α is an important factor in causing acute inflammatory damage to the lung. IL-4 is recognized to have both anti-inflammatory and immunomodulatory effects. Here, we found that the JAP treatment group could significantly reduce the mRNA levels of TLR-3 and TLR-4, down-regulate the expressions of pro-inflammatory factors TNF-α and TNF-β, and up-regulate the level of anti-inflammatory factor IL-4. The above results suggested that JAP may affect the downstream inflammatory factor levels by inhibiting the expression of TLR3 and TLR4, thereby intervening in the inflammatory response process of infected mice.

JAP, a type of inulin, is a recognized natural prebiotic, which is fermented in the gut to produce a large amount of short-chain fatty acids and significantly increase the number of bifidobacteria, thereby improving the intestinal flora [32, 33]. Furthermore, studies had shown that changes in the composition of gut microbiota and changes in the concentration of short-chain fatty acids in the gut were associated with RSV susceptibility [34, 35]. It is reported that JAP could also enhance intestinal mucosal immune function, and its underlying mechanism was related to the changes in intestinal flora caused by inulin fermentation [16, 36]. Based on the above studies, we also speculate that the intervention effect of JAP on RSV-induced pneumonia in mice might be related to its effects on intestinal mucosal immunity and intestinal flora. Therefore, the follow-up mechanism research will focus on intestinal mucosal immunity and changes in the intestinal flora. In addition to an in-depth study of its anti-RSV mechanism, we will also systematically evaluate the safety of JAP to lay the foundation for this study to enter human trials.

In conclusion, we preliminarily confirmed the anti-RSV effect of JAP in vitro and in vivo and found that its mechanism involved inhibiting TLR3/4 mRNA levels, down-regulating pro-inflammatory factors TNF-α and TNF-β levels, and up-regulating anti-inflammatory factor IL-4 levels. These data suggest the potential use of JAP as antiviral agent against RSV. However, further studies are needed to elucidate their mechanisms, which remain unclear.

Data Availability

The data used to support the findings of this study are available from the corresponding author upon reasonable request.

Conflicts of Interest

We declare that there are no conflicts of interest involved in this research work.

Authors’ Contributions

Xinhuan Wan and Zihao Liu contributed equally to this work.

Acknowledgments

This work was supported by the Shandong Provincial Natural Science Foundation (No. ZR2021MH232).

References

B. S. Graham, “Vaccine development for respiratory syncytial virus,” Current Opinion in Virology, vol. 23, pp. 107–112, 2017.
View at: Publisher Site | Google Scholar
N. I. Mazur, D. Higgins, M. C. Nunes et al., “The respiratory syncytial virus vaccine landscape: lessons from the graveyard and promising candidates,” The Lancet Infectious Diseases, vol. 18, no. 10, pp. e295–e311, 2018.
View at: Publisher Site | Google Scholar
J. E. Schuster and J. V. Williams, “Emerging respiratory viruses in children,” Infectious Disease Clinics of North America, vol. 32, no. 1, pp. 65–74, 2018.
View at: Publisher Site | Google Scholar
H. K. Talbot, E. A. Belongia, E. E. Walsh, and W. Schaffner, “Respiratory syncytial virus in older adults,” Infectious Diseases in Clinical Practice, vol. 24, no. 6, pp. 295–302, 2016.
View at: Publisher Site | Google Scholar
W. W. Thompson, D. K. Shay, E. Weintraub et al., “Mortality associated with influenza and respiratory syncytial virus in the United States,” JAMA, vol. 289, no. 2, pp. 179–186, 2003.
View at: Publisher Site | Google Scholar
N. Haber, “Infections a virus respiratoire syncytial du sujet age,” Médecine et Maladies Infectieuses, vol. 48, no. 6, pp. 377–382, 2018.
View at: Publisher Site | Google Scholar
A. T. Borchers, C. Chang, M. E. Gershwin, and L. J. Gershwin, “Respiratory syncytial virus--a comprehensive review,” Clinical Reviews in Allergy and Immunology, vol. 45, no. 3, pp. 331–379, 2013.
View at: Publisher Site | Google Scholar
M. S. Luna, P. Manzoni, B. Paes et al., “Expert consensus on palivizumab use for respiratory syncytial virus in developed countries,” Paediatric Respiratory Reviews, vol. 33, pp. 35–44, 2020.
View at: Publisher Site | Google Scholar
F. S. Burrows, L. M. Carlos, M. Benzimra et al., “Oral ribavirin for respiratory syncytial virus infection after lung transplantation: efficacy and cost-efficiency,” The Journal of Heart and Lung Transplantation, vol. 34, no. 7, pp. 958–962, 2015.
View at: Publisher Site | Google Scholar
Y. G. Cao, Y. Hao, Z. H. Li, S. T. Liu, and L. X. Wang, “Antiviral activity of polysaccharide extract from Laminaria japonica against respiratory syncytial virus,” Biomedicine & Pharmacotherapy, vol. 84, pp. 1705–1710, 2016.
View at: Publisher Site | Google Scholar
F. W. Ma, S. Y. Kong, H. S. Tan et al., “Structural characterization and antiviral effect of a novel polysaccharide PSP-2B from Prunellae Spica,” Carbohydrate Polymers, vol. 152, pp. 699–709, 2016.
View at: Publisher Site | Google Scholar
P. Dehghan, M. A. Farhangi, F. Tavakoli, A. Aliasgarzadeh, and A. M. Akbari, “Impact of prebiotic supplementation on T-cell subsets and their related cytokines, anthropometric features and blood pressure in patients with type 2 diabetes mellitus: a randomized placebo-controlled trial,” Complementary Therapies in Medicine, vol. 24, pp. 96–102, 2016.
View at: Publisher Site | Google Scholar
D. Letexier, F. Diraison, and M. Beylot, “Addition of inulin to a moderately high-carbohydrate diet reduces hepatic lipogenesis and plasma triacylglycerol concentrations in humans,” The American Journal of Clinical Nutrition, vol. 77, no. 3, pp. 559–564, 2003.
View at: Publisher Site | Google Scholar
A. R. Lobo, J. M. Filho, E. P. Alvares, M. L. Cocato, and C. Colli, “Effects of dietary lipid composition and inulin-type fructans on mineral bioavailability in growing rats,” Nutr, vol. 25, no. 2, pp. 216–225, 2009.
View at: Publisher Site | Google Scholar
I. A. Rubel, E. E. Pérez, D. B. Genovese, and G. D. Manrique, “In vitro prebiotic activity of inulin-rich carbohydrates extracted from Jerusalem artichoke (Helianthus tuberosus L.) tubers at different storage times by Lactobacillus paracasei,” Food Research International, vol. 62, pp. 59–65, 2014.
View at: Publisher Site | Google Scholar
P. D. Schley and C. J. Field, “The immune-enhancing effects of dietary fibres and prebiotics,” The British Journal of Nutrition, vol. 87, no. 6, pp. 221–230, 2002.
View at: Publisher Site | Google Scholar
M. Shoaib, A. Shehzad, M. Omar et al., “Inulin: properties, health benefits and food applications,” Carbohydrate Polymers, vol. 147, pp. 444–454, 2016.
View at: Publisher Site | Google Scholar
M. Dubois, K. A. Gilles, J. K. Hamilton, P. A. Rebers, and F. Smith, “Colorimetric method for determination of sugars and related substances,” Analytical Chemistry, vol. 28, no. 3, pp. 350–356, 1956.
View at: Publisher Site | Google Scholar
G. Miller, “Use of dinitrosalicylic acid reagent for determination of reducing sugar,” Analytical Chemistry, vol. 31, no. 3, pp. 426–428, 1959.
View at: Publisher Site | Google Scholar
M. Ilaghi, I. Sharifi, F. Sharififar et al., “The potential role and apoptotic profile of three medicinal plant extracts on Leishmania tropica by MTT assay, macrophage model and flow cytometry analysis,” Parasite Epidemiol Control, vol. 12, article e00201, 2021.
View at: Publisher Site | Google Scholar
X. H. Liu, D. L. Xin, A. C. Hou et al., “A mouse model of mycoplasma pneumoniae pneumonia,” Chongqing Medical Journal, vol. 33, no. 9, pp. 1338–1340, 2004.
View at: Publisher Site | Google Scholar
R. J. Martin, H. W. Chu, J. M. Honour, and R. J. Harbeck, “Airway inflammation and bronchial hyperresponsiveness after Mycoplasma pneumoniae infection in a murine model,” American Journal of Respiratory Cell and Molecular Biology, vol. 24, no. 5, pp. 577–582, 2001.
View at: Publisher Site | Google Scholar
S. Arora, S. Ahmad, R. Irshad et al., “TLRs in pulmonary diseases,” Life Sciences, vol. 233, p. 116671, 2019.
View at: Publisher Site | Google Scholar
L. A. O’Neill, D. Golenbock, and A. G. Bowie, “The history of Toll-like receptors -- redefining innate immunity,” Nature Reviews. Immunology, vol. 13, no. 6, pp. 453–460, 2013.
View at: Publisher Site | Google Scholar
P. R. Rauta, M. Samanta, H. R. Dash, B. Nayak, and S. Das, “Toll-like receptors (TLRs) in aquatic animals: signaling pathways, expressions and immune responses,” Immunology Letters, vol. 158, no. 1-2, pp. 14–24, 2014.
View at: Publisher Site | Google Scholar
R. T. Stein, D. Sherrill, W. J. Morgan et al., “Respiratory syncytial virus in early life and risk of wheeze and allergy by age 13 years,” Lancet, vol. 354, no. 9178, pp. 541–545, 1999.
View at: Publisher Site | Google Scholar
H. Feng, J. Fan, S. Yang, X. Zhao, and X. Yi, “Antiviral activity of phosphorylated Radix Cyathulae officinalis polysaccharide against Canine Parvovirus in vitro,” International Journal of Biological Macromolecules, vol. 99, pp. 511–518, 2017.
View at: Publisher Site | Google Scholar
T. Wang, X. Wang, Y. Zhuo et al., “Antiviral activity of a polysaccharide from Radix Isatidis (Isatis indigotica Fortune) against hepatitis B virus (HBV) in vitro via activation of JAK/STAT signal pathway,” Journal of Ethnopharmacology, vol. 257, p. 112782, 2020.
View at: Publisher Site | Google Scholar
H. Xue, F. Gan, Z. Zhang, J. Hu, X. Chen, and K. Huang, “Astragalus polysaccharides inhibits PCV2 replication by inhibiting oxidative stress and blocking NF-κB pathway,” International Journal of Biological Macromolecules, vol. 81, pp. 22–30, 2015.
View at: Publisher Site | Google Scholar
P. Liu, M. Jamaluddin, K. Li, R. P. Garofalo, A. Casola, and A. R. Brasier, “Retinoic acid-inducible gene I mediates early antiviral response and Toll-like receptor 3 expression in respiratory syncytial virus-infected airway epithelial cells,” Journal of Virology, vol. 81, no. 3, pp. 1401–1411, 2007.
View at: Publisher Site | Google Scholar
J. Marzec, H. Y. Cho, M. High, Z. R. McCaw, F. Polack, and S. R. Kleeberger, “Toll-like receptor 4-mediated respiratory syncytial virus disease and lung transcriptomics in differentially susceptible inbred mouse strains,” Physiological Genomics, vol. 51, no. 12, pp. 630–643, 2019.
View at: Publisher Site | Google Scholar
G. R. Gibson and M. B. Roberfroid, “Dietary modulation of the human colonic microbiota: introducing the concept of prebiotics,” The Journal of Nutritional Biochemistry, vol. 125, no. 6, pp. 1401–1412, 1995.
View at: Publisher Site | Google Scholar
J. Slavin, “Fiber and prebiotics: mechanisms and health benefits,” Nutr, vol. 5, no. 4, pp. 1417–1435, 2013.
View at: Publisher Site | Google Scholar
H. T. Groves, L. Cuthbertson, P. James, M. F. Moffatt, M. J. Cox, and J. S. Tregoning, “Respiratory disease following viral lung infection alters the murine gut microbiota,” Frontiers in Immunology, vol. 9, p. 182, 2018.
View at: Publisher Site | Google Scholar
H. T. Groves, S. L. Higham, M. F. Moffatt, M. J. Cox, and J. S. Tregoning, “Respiratory viral infection alters the gut microbiota by inducing inappetence,” mBio, vol. 11, no. 1, 2020.
View at: Publisher Site | Google Scholar
K. A. Kelly-Quagliana, P. D. Nelson, and R. K. Buddington, “Dietary oligofructose and inulin modulate immune functions in mice,” Nutrition Research, vol. 23, no. 2, pp. 257–267, 2003.
View at: Publisher Site | Google Scholar

Copyright

Copyright © 2022 Xinhuan Wan et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

PDF Download Citation

Download other formats

Order printed copies

Views

322

Downloads

371

Citations