Apigenin Attenuates Allergic Responses of Ovalbumin-Induced Allergic Rhinitis Through Modulation of Th1/Th2 Responses in Experimental Mice

The potential application and molecular mechanisms of natural products in the treatment of allergic rhinitis: A review

BACKGROUNDS

Allergic rhinitis (AR) is a non-infectious chronic inflammation of the nasal mucosa mainly mediated by immunoglobulin E (IgE) in atopic individuals after exposure to allergens. The application of AR guideline-recommended pharmacotherapies can rapidly relieve symptoms of AR but with poor long-term efficacy, and many of these therapies have side effects. Many natural products and their derivatives have shown potential therapeutic effects on AR with fewer side effects.

OBJECTIVES

This review aims to expand understanding of the roles and mechanisms of natural compounds in the treatment of AR and to highlight the importance of utilizing natural products in the treatment of AR.

MATERIAL AND METHOD

We conducted a systematic literature search using PubMed, Web of Science, Google Scholar, and Clinical Trials. The search was performed using keywords including natural products, natural compounds, bioproducts, plant extracts, naturally derived products, natural resources, allergic rhinitis, hay fever, pollinosis, nasal allergy. Comprehensive research and compilation of existing literature were conducted.

RESULTS

This article provided a comprehensive review of the potential therapeutic effects and mechanisms of natural compounds in the treatment of AR. We emphasized that natural products primarily exert their effects by modulating signalling pathways such as NF-κB, MAPKs, STAT3/ROR-γt/Foxp3, and GATA3/T-bet, thereby inhibiting the activation and expansion of allergic inflammation. We also discussed their toxicity and clinical applications in AR therapy.

CONCLUSION

Taken together, natural products exhibit great potential in the treatment of AR. This review is also expected to facilitate the application of natural products as candidates for treating AR. Furthermore, drug discovery based on natural products has a promising prospect in AR treatment.

Anti-Allergic and Anti-inflammatory Effects of Bakuchiol on Ovalbumin-Induced Allergic Rhinitis in Mice

Allergic rhinitis (AR) is a prevalent inflammatory disease primarily affecting the nasal mucosa and is caused by allergies. The common symptoms of AR include rhinorrhea, sneezing, itchy nose, congestion, teary eyes, and nasal rubbings. The present study assessed the beneficial properties of bakuchiol on OVA-induced AR in mice via the regulation of inflammatory responses. AR was induced by injecting (i.p.) OVA (50 µg) and aluminum hydroxide (1 mg) into mice at various time intervals. The bakuchiol treatment was done at dosages of 10 and 20 mg/kg with dexamethasone (2.5 mg/kg) as a positive control. The body weight and nasal symptoms were measured on the day of the last OVA challenge. For in vitro tests, mouse splenocytes were isolated, sensitized with 20 µL OVA, and then treated with 10 µM bakuchiol. The levels of pro-inflammatory cytokines, immunoglobulins, histamine, leukotriene C4 (LTC-4), and prostaglandin D2 (PGD2) were assayed using the corresponding assay kits. The assay kits were also used to analyze the status of oxidative stress markers. The Th1/Th2 cell proportion was assessed using flow cytometry. The bakuchiol (10 and 20 mg/kg) treatment reduced the nasal symptoms in AR mice. Bakuchiol decreased the levels of IL-4, IL-5, IL-13, Igs (IgE and IgG1), histamine, IL-10, IL-33, and TNF-α in AR mice. Bakuchiol also reduced PGDA and LTC-4 levels in the NLF of AR mice. The ROS and MDA levels were decreased, whereas boosted SOD activity was observed in the bakuchiol-treated AR mice. The eosinophil count was decreased in the nasal tissues of bakuchiol-treated AR mice. Bakuchiol also influenced the Th1 and Th2 cell proportions in AR mice. The present findings suggest that bakuchiol is effective against OVA-mediated allergic and inflammatory responses in AR mice through its strong anti-inflammatory properties.

miR-224-5p Attenuates Allergic Responses in Mice with Allergic Rhinitis by Modulating the Th1/Th2 Response

Background

Allergic rhinitis (AR) is a common chronic respiratory disease that has become a global health problem. miRNAs play an important role in multiple immune and inflammatory diseases, including AR. In this work, the mechanism by which miR-224-5p regulates AR in vivo and in vitro was examined.

Methods

Human nasal epithelial cells (HNEpCs) were used to establish an AR cell model induced by Der P1, and C57BL/6 mice were used to establish an AR animal model induced by OVA (ovalbumin). RT-qPCR was used to determine the level of miR-224-5p; western blot analysis was used to determine GATA3; ELISA was used to determine the levels of OVA-specific IgE, IFN-γ, IL-4, IL-5, and IL-13; flow cytometry was used to determine the differentiation of Th1 and Th2 cells; and HE and PAS staining was used to observe the histopathological alterations in the mouse nasal mucosa and spleen.

Results

miR-224-5p was downregulated in nasal mucosa from mice with AR and an AR cell model. Overexpressed miR-224-5p can improve AR development and attenuate AR symptoms by regulating GATA3-mediated Th1/Th2 responses.

Conclusion

miR-224-5p attenuates allergic reactions in mice with AR by regulating the Th1/Th2 response.

RORα overexpression reduced interleukin-33 expression and prevented mast cell degranulation and inflammation by inducing autophagy in allergic rhinitis

BACKGROUND

Retinoid acid receptor related orphan receptor α (RORα) is a nuclear receptor that along with other bioactive factors regulates cell proliferation, differentiation, and immunomodulation in vivo.

AIMS

The objective of this study was to explore the function and mechanism of RORα in allergic rhinitis (AR).

MATERIALS AND METHODS

Derp1 was used to construct an AR cell model in HNEpC cells, and RORα was overexpressed or silenced in the AR HNEpC cells. Next, LAD2 cells were co-cultured with the Derp1-treated HNEpC cells. Additionally, an AR mouse model was established using by OVA, and a RORα Adenovirus was delivered by nebulizing. Pathological tissue structures were evaluated by hematoxylin-eosin staining, and the levels of RORα, interleukin-33 (IL-33), and other proteins were analyzed immunohistochemistry, western blotting, and immunofluorescence staining. IL-33, IL-4, IL-5, and IL-13 levels were detected using enzyme-linked immunosorbent assay kits and cell migration was assessed by Transwell assays.

RESULTS

Our data showed that RORα was downregulated in the nasal mucosa tissues of AR patients. Derp1 treatment could cause a downregulation of RORα, upregulation of IL-33, the induction of NLRP3 inflammasomes, and cell migration in HNEpC cells. Furthermore, RORα overexpression dramatically attenuated IL-33 levels, NLRP3 inflammasome activity, and the migration of AR HNEpC cells induced with Derp1. Moreover, RORα in AR HNEpC cells could prevent mast cell (MC) degranulation and inflammation by accelerating autophagy, RORα overexpression inhibited MC degranulation and NLRP3-induced inflammation in the AR model mice. RORα overexpression reduced IL-33 expression in nasal epithelial cells, and also suppressed MC degranulation and inflammation by promoting autophagy.

CONCLUSION

RORα inhibits NLRP3 inflammasome in HNEpC, and attenuated mast cells degranulation and inflammation through autophagy in AR.

Luteolin restored Treg/Th17 balance to ameliorate allergic rhinitis in a mouse model

OBJECTIVE

Luteolin (LO) has been reported to be a potential drug for allergic rhinitis (AR). This paper explored the mechanism of LO in AR.

MATERIALS AND METHODS

Mice were treated with ovalbumin (OVA) to construct an AR model in vivo before LO or 3-methyladenine (3-MA) treatment. The frequency of nasal sneezing was counted. The nasal mucosa thickness was assessed by hematoxylin-eosin staining assay. The levels of anti-OVA-immunoglobulin E (IgE)/IgG2a, autophagy-related factors (Beclin1, LC3II/LC3I), and T helper cell 17 (Th17)/regulatory T cell (Treg) markers (interleukin (IL)-17A, retinoic acid receptor-related orphan nuclear receptor γt (RORγt)/IL-10, forkhead box P3 (Foxp3)) were detected through enzyme-linked immunosorbent assay, western blot, and quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Flow cytometry assay was performed to test the percentage of Th17 and Treg cells.

RESULTS

The nasal sneezing frequency, nasal mucosa thickness, and levels of anti-OVA-IgE, Beclin1, LC3II/LC3I, IL-17A as well as RORγt were enhanced whereas anti-OVA-IgG2a, IL-10, and Foxp3 levels were inhibited in a mouse model of OVA-induced AR, which were reversed by LO or 3-MA treatment.

CONCLUSIONS

LO restored Treg/Th17 balance to ameliorate AR in a mouse model.

Apigenin attenuates inflammatory response in allergic rhinitis mice by inhibiting the TLR4/MyD88/NF-κB signaling pathway

BACKGROUND

Allergic rhinitis (AR) is an immunoglobulin E (IgE)-mediated immune inflammatory response that mainly affects the nasal mucosa. Currently, there is evidence that apigenin, as a flavonoid, has anti-allergic potential.

MATERIAL/METHODS

In vitro, compound 48/80 and lipopolysaccharide (LPS) were used to induce mast cell activation and inflammation in HMC-1 cells. In vivo, ovalbumin (OVA) induced and stimulated AR in BALB/c mice. ELISA was used to detect the contents of β-hexosaminidase, histamine, eosinophil cationic protein (ECP), OVA-specific IgE, IgG1, and IgG2a, inflammatory factors in cells and mouse serum. Cell viability and apoptosis were measured with MTT and flow cytometry. Toll like receptor 4 (TLR4)/myeloid differentiation factor88 (MyD88)/Nuclear transcription factor-κB (NF-κB) pathway-related proteins in cells and mouse nasal mucosa tissues were analyzed with Western blotting. The levels of Th1 (IFN-γ) and Th2 (IL-4, IL-5, and IL-13) cytokines and Th1 (T-bet) and Th2 (GATA-3) specific transcription factors were also assessed. The ratio of Th1 (CD4⁺ IFN-γ⁺ ) / Th2 (CD4⁺ IL-4⁺ ) cells in mouse peripheral blood mononuclear cells was evaluated by flow cytometry.

RESULTS

Apigenin significantly inhibited compound 48/80-induced secretion of β-hexosaminidase and histamine. Apigenin blocked LPS-induced decrease in cell viability and increase in cell apoptosis and inflammatory cytokine secretion by suppressing the activity of the TLR4/MyD88/NF-κB pathway. Apigenin treatment reduced the levels of OVA-specific IgE, IgG1 and IgG2a as well as β-hexosaminidase, histamine and ECP levels in mouse serum. Moreover, administration with apigenin decreased Th2 cytokine and transcription factor levels and increased Th1 cytokine and transcription factor levels, and promoted the ratio of Th1/Th2 cells in AR mice. Additionally, apigenin significantly alleviated nasal symptoms and nasal eosinophil infiltration in AR mice.

CONCLUSIONS

Apigenin alleviates the inflammatory response of allergic rhinitis by inhibiting the activity of the TLR4/MyD88/NF-κB signaling pathway.

Apigenin: A Therapeutic Agent for Treatment of Skin Inflammatory Diseases and Cancer

The skin is the main barrier between the body and the environment, protecting it from external oxidative stress induced by ultraviolet rays. It also prevents the entrance of infectious agents such as viruses, external antigens, allergens, and bacteria into our bodies. An overreaction to these agents causes severe skin diseases, including atopic dermatitis, pruritus, psoriasis, skin cancer, and vitiligo. Members of the flavonoid family include apigenin, quercetin, luteolin, and kaempferol. Of these, apigenin has been used as a dietary supplement due to its various biological activities and has been shown to reduce skin inflammation by downregulating various inflammatory markers and molecular targets. In this review, we deal with current knowledge about inflammatory reactions in the skin and the molecular mechanisms by which apigenin reduces skin inflammation.

Aqueous Extract from Cuminum cyminum L. Seed Alleviates Ovalbumin-Induced Allergic Rhinitis in Mouse via Balancing of Helper T Cells

Cuminum cyminum L. (cumin) seeds are widely used as a spice. Although we previously reported that the aqueous extract of cumin seeds suppresses the degranulation of rat basophilic RBL-2H3 cells, it has not been clarified whether the extract alleviates actual allergy symptoms in vivo. Therefore, in this study, we investigated the effect of oral administration of cumin seed aqueous extract (CAE) in ovalbumin (OVA)-induced allergic rhinitis. BALB/c mice were randomly divided into the following three groups: control group (five mice), OVA group (five mice), and OVA + CAE group (five mice). Allergic rhinitis was induced by sensitization (intraperitoneal, 25 μg OVA and 1.98 mg aluminum hydroxide gel) followed by challenge (intranasal, 400 μg OVA). The oral administration of CAE (25 mg/kg) reduced the sneezing frequency of OVA-induced allergic rhinitis model mice. In addition to reducing the serum immunoglobulin E and IL-4 levels, the oral administration of CAE reduced the production of T-helper type-2 (Th2) cytokines (IL-4, IL-5, IL-10, and IL-13) in the splenocytes of the model mice. Furthermore, a significant increase in the ratio of Th1 to Th2 cells was observed in the CAE-administered group. Our findings suggest that the ingestion of CAE improves T cell balance, the dominant state of Th2, and alleviates allergic rhinitis symptoms.

Canavalia gladiata Pod Extract Mitigates Ovalbumin-Induced Asthma Onset in Male BALB/c Mice via Suppression of MAPK

Asthma is one of the most common inflammatory diseases of the lung worldwide. There has been considerable progress in recent studies to treat and prevent allergic asthma, however, various side effects are still observed in clinical practice. Six-week-old male BALB/c mice were orally administered with either sword bean pod extracts (SBP; 100 or 300 mg/kg) or dexamethasone (DEX; 5 mg/kg) once daily over 3 weeks, followed by ovalbumin sensitization (OVA/Alum.; intraperitoneal administration, 50 μg/2 mg/per mouse). Scoring of lung inflammation was performed to observe pathological changes in response to SBP treatment compared to OVA/Alum.-induced lung injury. Additionally, inflammatory cytokines were quantified in serum, bronchoalveolar lavage fluid (BALF), and lung tissue using ELISA and Western blot analyses. SBP treatment significantly reduced the infiltration of inflammatory cells, and release of histamine, immunoglobulin E, and leukotriene in serum and BALF. Moreover, the therapeutic effect of SBP was also assessed to analyze the inflammatory changes in the lung tissues. SBP markedly suppressed the activation of the MAPK signaling pathway and the expression of key inflammatory proteins (e.g., TNF-α) and Th2 type cytokines (IL-5 and IL-13). SBP was effective in ameliorating the allergic inflammation against OVA/Alum.-induced asthma by suppressing pulmonary inflammation.

Febuxostat Alleviates Allergic Rhinitis by Inhibiting Inflammation and Monocyte Adhesion in Human Nasal Epithelial Cells via Regulating KLF6

Introduction

Febuxostat is a novel inhibitor of xanthine oxidase that suppresses cell adhesion molecules-mediated (CAMs) inflammation by activating KLF6. In this study, we explored the therapeutic function and potential mechanisms of febuxostat against allergic rhinitis (AR).

Methods

We investigated the role of febuxostat through in vitro cell and in vivo animal experiments. Human nasal epithelial cells (hNECs) were cultured with histamine as an in vitro model. To establish the AR animal model, rats were exposed to ovalbumin. Rats were randomly grouped into control, model, 7.5 mg/kg febuxostat, and 15 mg/kg febuxostat groups.

Results

In the in vitro study, we found significantly increased release of lactate dehydrogenase, elevated production of inflammatory factors and chemokines, and upregulated CAMs in histamine-treated hNECs. However, these results were significantly reversed for the 10 and 20 μM febuxostat treatments. The enhanced adhesion between hNECs and monocytes induced by histamine was dramatically repressed by febuxostat. In the vivo experiments, we observed that febuxostat ameliorated the increased sneezing times, the number of nose scratching episodes, and elevated HE pathological scores as well as alleviated the inflammation in nasal mucous tissues of AR mice. We found that KLF6, which was downregulated in histamine-treated hNECs, was significantly upregulated by febuxostat. The inhibitory effects of febuxostat on the expression levels of CAMs and adhesion between histamine-treated hNECs and monocytes were significantly abolished by the knockdown of KLF6.

Conclusion

Febuxostat alleviates AR by inhibiting inflammation and monocyte adhesion in human nasal epithelial cells through the regulation of KLF6.

Molecular and Immunomodulatory Actions of New Antiasthmatic Agents: Exploring the Diversity of Biologics in Th2 Endotype Asthma

Asthma is a major respiratory disorder characterised by chronic inflammation and airway remodelling. It affects about 1-8% of the global population and is responsible for over 461,000 deaths annually. Until recently, the pharmacotherapy of severe asthma involved high doses of inhaled corticosteroids in combination with β-agonist for prolonged action, including theophylline, leukotriene antagonist or anticholinergic yielding limited benefit. Although the use of newer agents to target Th2 asthma endotypes has improved therapeutic outcomes in severe asthmatic conditions, there seems to be a paucity of understanding the diverse mechanisms through which these classes of drugs act. This article delineates the molecular and immunomodulatory mechanisms of action of new antiasthmatic agents currently being trialled in preclinical and clinical studies to remit asthmatic conditions. The ultimate goal in developing antiasthmatic agents is based on two types of approaches: either anti-inflammatory or bronchodilators. Biologic and most small molecules have been shown to modulate specific asthma endotypes, targeting thymic stromal lymphopoietin, tryptase, spleen tyrosine kinase (Syk), Janus kinase, PD-L1/PD-L2, GATA-3, and CD38 for the treatment and management of Th2 endotype asthma.

An integrative review on the uses of plant-derived bioactives formulated in conventional and innovative dosage forms for the local treatment of damaged nasal cavity

Plants and their derivates have been used as medicines for centuries and today is being re-discovered their usefulness for the human health. The therapeutic properties of phytochemicals are re-evaluated under the light of medical and pharmacological research, pushed by a constantly growing market demand, where consumers trust more natural products than synthetic drugs. New studies are enlightening the effectiveness of phytochemicals against a wide range of ailments, nevertheless very few evaluate the efficacy of topical formulations based on natural bioactive molecules in the treatment of nasal mucosal diseases. This review aims at exploring this little covered topic. An overview on the properties and functionality of the nasal mucosa and the different diseases affecting it has been provided. We summarized various nasal dosage forms containing natural bioactive and explored how innovative delivery systems loading phytochemicals can improve the treatment results. Finally, the potential use of novel nanocarriers for the treatment of nasal ailments has been covered as well.

Ajwain oil attenuates allergic response of ovalbumin-induced allergic rhinitis via alteration of inflammatory, oxidative stress, and Th1/Th2 responses

BACKGROUND

Allergic rhinitis (AR) is an immune inflammatory-related disorder that affects the nasal mucosa. Free radicals play a crucial role in the expansion of allergic reaction and the researcher used the antioxidant therapy to treat the disease. Trachyspermum ammi L. (Ajwain oil) is popular traditional medicine. It has been proved their potential effect on various diseases. Ajwain oil showed anti-tumor, antioxidant, antidiabetic, anti-inflammatory, and anti-bacterial properties. Yet, the anti-allergic effect of Ajwain oil is still not explored. In this experimental study, an ovalbumin (OVX)-induced AR model was used to scrutinize the anti-allergic, antioxidant and anti-inflammatory effects of Ajwain oil.

MATERIALS AND METHODS

OVX was used to establish the AR model (sensitization days 1, 8, and 15) and given the oral treatment of Ajwain oil and Montelukast for 13 days. The spleen, lungs, and body weight were estimated. Sneezing, nasal discharge and rubbing are also estimated. Immunoglobin-E (IgE), histamine, malondialdehyde (MDA), superoxide dismutase (SOD), heme oxygenase-1 (HO-1), nuclear factor erythroid 2-related factor 2 (Nrf2), and inflammatory cytokines were scrutinized.

RESULTS

Ajwain oil significantly (p < .001) suppressed sneezing, nasal discharge and nasal rubbing along with increasing the spleen, lung and body weight. Ajwain oil significantly (p < .001) decreased the level of IgE, histamine, MDA, Nrf2, HO-1, and increased the level of SOD. Ajwain oil significantly (p < .001) suppressed the number of eosinophils, neutrophils, macrophages, and epithelial cells. Ajwain oil significantly prevented the activation of the NF-κBp65 and STAT3 signaling pathways that led to enhancing the synthesis of anti-inflammatory cytokines and reducing the inflammatory, allergen-specific type 2T helper cells (Th2), Th17 cytokines.

CONCLUSION

The obtained data suggests that Ajwain oil has a promising anti-allergic against allergic rhinitis in mice via anti-allergic, antioxidant, and anti-inflammatory effects.

PRACTICAL APPLICATIONS

Allergic rhinitis is a serious life-threatening disease. Inflammatory reaction plays an important role in the expansion of AR diseases. Ajwain oil considerably increased the spleen weight and reduced lung weight. Ajwain oil suppressed the nasal rubbing, sneezing, and nasal discharge. Ajwain oil considerably suppressed the immunoglobin and inflammatory cytokines. The result suggests that Ajwain oil having the potential effect against the allergic rhinitis.

Biomimetic amphiphilic FAAP NPs nanoparticles: Synthesis, characterization and antivirus activity

Antiviral agents based on natural products have attracted substantial attention in clinical applications for their distinct biological activities,molecular structuralmultiformities, and low biotoxicities. Ferulic acid (FA) with apigenin propaneto form an esterified FA derivative (FAAP).Herein, we designed a CsPbBr3-modified chitosan oligosaccharide, a biomimetic nanoplatform that could load with FAAP. After self-assembly by combining FAAP with CsPbBr3-modified chitosan oligosaccharide (FAAP NPs), the resulting nanoparticles (FAAP NPs) showed high antioxidant and anti-inflammatory activities for enhancing the inhibition of porcineparvovirus.FAAP NPs exhibited no signs of acute toxicity in vitro or in vivo. DPPH and ABST are widely used for quantitative determination of antioxidant capacity. FAAP NPs exhibited excellent DPPH and ABTS radical scavenging abilities. In addition, we found that FAAP NPs inhibited PPV infection-induced PK-15 cell apoptosis, which was associated with regulating antioxidant and anti-inflammatory signaling pathways. Importantly, we showed that FAAP NPs blocked PPV infection-induced mitochondrial apoptosis in PK-15 cells via a p53/BH3 domain molecular-dependent mechanism.

Pharmacological Effects of Polyphenol Phytochemicals on the JAK-STAT Signaling Pathway

The JAK-STAT signaling pathway is a common pathway of many cytokine signal transductions, closely related to cell proliferation, apoptosis, differentiation, and inflammatory response. It is essential for inhibiting the inflammatory response, initiating innate immunity, and coordinating adaptive immune mechanisms. Owing to the nature of this pathway and its potential cross-epitopes with multiple alternative pathways, the long-term efficacy of monotherapy-based adaptive targeting therapy is limited, and the majority of drugs targeting STATs are still in the preclinical phase. Meanwhile, curcumin, quercetin, and several kinds of plant polyphenol chemicals play roles in multiple sites of the JAK-STAT pathway to suppress abnormal activation. Polyphenol compounds have shown remarkable effects by acting on the JAK-STAT pathway in anti-inflammatory, antitumor, and cardiovascular disease control. This review summarizes the pharmacological effects of more than 20 kinds of phytochemicals on JAK-STAT signaling pathway according to the chemical structure of polyphenolic phytochemicals.

Inhibition of Angiogenic Factor Productions by Quercetin In Vitro and In Vivo

Background: Angiogenesis is well known to be an important event in the tissue remodeling observed in allergic diseases. Although there is much evidence that quercetin, one of the most abundant dietary flavonoids, exerts anti-allergic effects in both human and experimental animal models of allergic diseases, the action of quercetin on angiogenesis has not been defined. Therefore, in this study, we first examined the action of quercetin on the secretion of angiogenic factors from murine mast cells in vitro. We also examined the action of quercetin on angiogenic factor secretion in the murine allergic rhinitis model in vivo. Methods: Mast cells (1 × 105 cells/mL) sensitized with ovalbumin (OVA)-specific murine IgE were stimulated with 10.0 ng/mL OVA in the presence or the absence of quercetin for 24 h. The concentrations of angiogenic factors, vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), tumor necrosis factor-α, IL-6 and IL-8 in the supernatants were examined by ELISA. BALB/c male mice immunized with OVA were challenged intranasally with OVA every other day, starting seven days after the final immunization. These mice were then orally administered quercetin once a day for five days, starting seven days after the final immunization. Clinical symptoms were assessed by counting the number of sneezes and nasal rubbing behaviors during the 10 min period just after OVA nasal provocation. The angiogenic factor concentrations in the nasal lavage fluids obtained 6 h after nasal antigenic provocation were examined by ELISA. Results: Quercetin significantly inhibited the production of angiogenetic factors induced by IgE-dependent mechanisms at 5.0 µM or more. Oral administration of 25.0 mg/kg quercetin into the mice also suppressed the appearance of angiogenetic factors in nasal lavage fluids, along with the attenuation of nasal symptoms. Conclusions: These results strongly suggest that the inhibitory action of quercetin on angiogenic factor secretion may be implicated in the therapeutic action of quercetin on allergic diseases, especially allergic rhinitis.

Luteolin ameliorates inflammation and Th1/Th2 imbalance via regulating the TLR4/NF-κB pathway in allergic rhinitis rats

OBJECTIVE

Luteolin has an anti-allergic effect but its mechanism is not clear. This study attempted to determine the mechanisms of luteolin in rhinitis.

METHODS

Allergic rhinitis rat model was established by ovalbumin (OVA) stimulation. Then, the rats were treated with normal saline, luteolin, or lipopolysaccharide (LPS) for 14 days. Nasal symptoms were scored; the histopathological changes of nasal mucosa were detected by hematoxylin-eosin staining. Serum levels of Th1 type cytokines (IFN-γ, IL-2), Th2 type cytokines (IL-4, IL-5, IL-13), and OVA-specific IgE (sIgE) were determined by ELISA. The expressions of Toll-like receptor 4 (TLR4) and p65 in nasal mucosa were detected by Western blot or immunohistochemistry.

RESULTS

Luteolin decreased symptom scores, specifically, the scores in control group, model group, model + 0.1 mg/kg luteolin, model + 1 mg/kg luteolin, and model + 10 mg/kg luteolin groups were 0.63 ± 0.52, 7.88 ± 0.83, 1.38 ± 0.52, 2.75 ± 0.46, and 5.00 ± 0.53, respectively. Luteolin ameliorated nasal mucosa inflammation by promoting the down-regulated levels of Th1 type cytokines, and suppressing the up-regulated levels of Th2 type cytokines, OVE-sIgE, TLR4, and p65. LPS further increased symptom scores, aggravated nasal mucosa inflammation, improved the unbalance of Th1/Th2 type cytokines, and lowered the expressions of OVE-sIgE, TLR4, and p65. Moreover, LPS reversed the effect of luteolin on allergic rhinitis rats.

CONCLUSION

Luteolin ameliorated inflammation and Th1/Th2 imbalance via regulating the TLR4/NF-κB pathway in allergic rhinitis rats. This study provided novel evidence that luteolin could be used as a candidate drug in allergic rhinitis treatment.

Chlorogenic acid ameliorated allergic rhinitis-related symptoms in mice by regulating Th17 cells

Allergic rhinitis (AR) is a non-infectious chronic inflammatory disease of nasal mucosa provoking T helper cell (Th) 17 response. Chlorogenic acid (CGA), one of the most abundant polyphenol compounds in various agricultural products, possesses antiviral, anti-inflammatory, and antibacterial properties. However, the effect of CGA on AR is unclear. Thus, our study explored the effect of CGA in modulating AR-related symptoms and immunoreaction, especially Th17 response. AR mice were induced by ovalbumin (OVA) administration and further treated with CGA or dexamethasone (Dex). The frequencies of rubbing and sneezing of AR mice were recorded. Histopathological analysis of nasal mucosa was conducted by Hematoxylin–Eosin and Periodic acid–Schiff stainings. The serum and nasal mucosa levels of OVA-immunoglobulin (Ig)E, interferon (IFN)-γ, retinoic acid-associated nuclear orphan receptor (ROR)-γt, and interleukin (IL)-17A were measured by enzyme-linked immunosorbent assay, quantitative reverse-transcription polymerase chain reaction (qRT-PCR), or Western blot. The ratio of CD4⁺IL-17⁺Th17 cells to CD4⁺ T cells in peripheral blood of AR mice was assessed by flow cytometer. CGA diminished the frequencies of rubbing and sneezing of AR mice in a concentration-dependent manner. CGA attenuated histopathological abnormalities and decreased goblet cell number in nasal mucosa of AR mice. CGA decreased the serum levels of OVA-IgE, ROR-γt, and IL-17A, while increasing the serum level of IFN-γ in AR mice. Meanwhile, CGA decreased the ratio of CD4⁺IL-17⁺Th17 cells to CD4⁺T cells in peripheral blood and the mRNA and protein levels of IL-17A and ROR-γt in AR mice. CGA ameliorated AR-related symptoms in mice by regulating Th17 cells, which could be a candidate for the treatment of AR.