Effect of treatment with geraniol on ovalbumin-induced allergic asthma in mice

Phytochemicals as treatment for allergic asthma: Therapeutic effects and mechanisms of action

BACKGROUND

Allergic asthma is an inflammatory disease caused by the immune system's reaction to allergens, inflammation and narrowing of the airways, and the production of more than normal mucus. One of the main reasons is an increased production of inflammatory cytokines in the lungs that leads to the appearance of symptoms of asthma, including inflammation and shortness of breath. On the other hand, it has been proven that phytochemicals with their antioxidant and anti-inflammatory properties can be useful in improving allergic asthma.

PURPOSE

Common chemical treatments for allergic asthma include corticosteroids, which have many side effects and temporarily relieve symptoms but are not a cure. Therefore, taking the help of natural compounds to improve the quality of life of asthmatic patients can be a valuable issue that has been evaluated in the present review.

STUDY DESIGN AND METHODS

In this study, three databases (Scopus, PubMed, and Cochrane) with the keywords: allergic asthma, phytochemical, plant, and herb were evaluated. The primary result was 5307 articles. Non-English, repetitive, and review articles were deleted from the study.

RESULTS AND DISCUSSION

Finally, after carefully reading the articles, 102 were included in the study (2006-2022). The results of this review state that phytochemicals suppress the inflammatory pathways via inhibition of inflammatory cytokines production/secretion, genes, and proteins involved in the inflammation process, reducing oxidative stress indicators and symptoms of allergic asthma, such as cough and mucus production in the lungs.

CONCLUSION

With their antioxidant effects, this study concluded that phytochemicals suppress cytokines and other inflammatory indicators and thus can be considered an adjunctive treatment for improving allergic asthma.

Herbal medicine for the treatment of obesity-associated asthma: a comprehensive review

Obesity is fast growing as a global pandemic and is associated with numerous comorbidities like cardiovascular disease, hypertension, diabetes, gastroesophageal reflux disease, sleep disorders, nephropathy, neuropathy, as well as asthma. Studies stated that obese asthmatic subjects suffer from an increased risk of asthma, and encounter severe symptoms due to a number of pathophysiology. It is very vital to understand the copious relationship between obesity and asthma, however, a clear and pinpoint pathogenesis underlying the association between obesity and asthma is scarce. There is a plethora of obesity-asthma etiologies reported viz., increased circulating pro-inflammatory adipokines like leptin, resistin, and decreased anti-inflammatory adipokines like adiponectin, depletion of ROS controller Nrf2/HO-1 axis, nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3) associated macrophage polarization, hypertrophy of WAT, activation of Notch signaling pathway, and dysregulated melanocortin pathway reported, however, there is a very limited number of reports that interrelates these pathophysiologies. Due to the underlying complex pathophysiologies exaggerated by obese conditions, obese asthmatics respond poorly to anti-asthmatic drugs. The poor response towards anti-asthmatic drugs may be due to the anti-asthmatics approach only that ignores the anti-obesity target. So, aiming only at the conventional anti-asthmatic targets in obese-asthmatics may prove to be futile until and unless treatment is directed towards ameliorating obesity pathogenesis for a holistic approach towards amelioration of obesity-associated asthma. Herbal medicines for obesity as well as obesity-associated comorbidities are fast becoming safer and more effective alternatives to conventional drugs due to their multitargeted approach with fewer adverse effects. Although, herbal medicines are widely used for obesity-associated comorbidities, however, a limited number of herbal medicines have been scientifically validated and reported against obesity-associated asthma. Notable among them are quercetin, curcumin, geraniol, resveratrol, β-Caryophyllene, celastrol, tomatidine to name a few. In view of this, there is a dire need for a comprehensive review that may summarize the role of bioactive phytoconstituents from different sources like plants, marine as well as essential oils in terms of their therapeutic mechanisms. So, this review aims to critically discuss the therapeutic role of herbal medicine in the form of bioactive phytoconstituents against obesity-associated asthma available in the scientific literature to date.

Potential Effects of Geraniol on Cancer and Inflammation-Related Diseases: A Review of the Recent Research Findings

Geraniol (GNL), a natural monoterpene, is found in many essential oils of fruits, vegetables, and herbs, including lavender, citronella, lemongrass, and other medicinal and aromatic plants. GNL is commonly used by the cosmetic and food industries and has shown a wide spectrum of pharmacological activities including anti-inflammatory, anticancer, antimicrobial, antioxidant, and neuroprotective activities. It represents a potential anti-inflammatory agent and a promising cancer chemopreventive agent, as it has been found to be effective against a broad range of cancers, including colon, prostate, breast, lung, skin, kidney, liver, and pancreatic cancer. Moreover, GNL scavenges free radicals and preserves the activity of antioxidant enzymes. In addition, GNL induces apoptosis and cell cycle arrest, modulates multiple molecular targets, including p53 and STAT3, activates caspases, and modulates inflammation via transcriptional regulation. In the present study, different modes of action are described for GNL's activity against cancer and inflammatory diseases. This compound protects various antioxidant enzymes, such as catalase, glutathione-S-transferase, and glutathione peroxidase. Experiments using allergic encephalomyelitis, diabetes, asthma, and carcinogenesis models showed that GNL treatment had beneficial effects with low toxicity. GNL has been shown to be effective in animal models and tumor cell lines, but there have not been any clinical studies carried out for it. The aim of the present review is to provide updated data on the potential effects of GNL on cancer and inflammation, and to enhance our understanding of molecular targets, involved pathways, and the possible use of GNL for clinical studies and therapeutic purposes in the treatment of cancer and inflammation-related diseases.

Review of industry reports on EU priority tobacco additives part A: Main outcomes and conclusions

The European Union Tobacco Products Directive (EU TPD) mandates enhanced reporting obligations for tobacco manufacturers regarding 15 priority additives. Within the Joint Action on Tobacco Control (JATC), a review panel of independent experts was appointed for the scientific evaluation of the additive reports submitted by a consortium of 12 tobacco manufacturers. As required by the TPD, the reports were evaluated based on their comprehensiveness, methodology and conclusions. In addition, we evaluated the chemical, toxicological, addictive, inhalation facilitating and flavoring properties of the priority additives based on the submitted reports, supplemented by the panel's expert knowledge and some independent literature. The industry concluded that none of the additives is associated with concern. Due to significant methodological limitations, we question the scientific validity of these conclusions and conclude that they are not warranted. Our review demonstrates that many issues regarding toxicity, addictiveness and attractiveness of the additives have not been sufficiently addressed, and therefore concerns remain. For example, menthol facilitates inhalation by activation of the cooling receptor TRPM8. The addition of sorbitol and guar gum leads to a significant increase of aldehydes that may contribute to toxicity and addictiveness. Titanium dioxide particles (aerodynamic diameter <10 µm) are legally classified as carcinogenic when inhaled. For diacetyl no report was provided. Overall, the industry reports were not comprehensive, and the information presented provides an insufficient basis for the regulation of most additives. We, therefore, advise MS to consider alternative approaches such as the precautionary principle.

Geraniol Ameliorates Doxorubicin-Mediated Kidney Injury through Alteration of Antioxidant Status, Inflammation, and Apoptosis: Potential Roles of NF-κB and Nrf2/Ho-1

Doxorubicin-mediated kidney impairment is a serious problem in cancer treatment. Accordingly, this work investigated the ability of geraniol to modulate doxorubicin-induced kidney damage using a rat model. Rats were randomly assigned to four groups: control, doxorubicin (20 mg/kg, intraperitoneal, i.p.), doxorubicin plus 100 mg/kg of geraniol, and doxorubicin plus 200 mg/kg of geraniol. A single doxorubicin injection triggered kidney impairment, as evidenced by the altered serum creatinine, blood urea nitrogen, and albumin values; it also caused histological changes in the kidney architecture. Additionally, doxorubicin enhanced lipid peroxidation while lowering reduced glutathione, catalase activity, and the expression of glutathione peroxidase and superoxide dismutase. Interestingly, pre-treatment with geraniol rescued doxorubicin-induced alterations in kidney antioxidant parameters, enzymatic activity, and the expression of inflammatory and apoptosis-mediating gene and proteins. Moreover, prophylactic treatment with geraniol preserved most kidney histological characteristics in a dose-dependent manner. These findings support that geraniol could protect against doxorubicin-mediated kidney dysfunction. However, further research is needed to clarify the mechanisms of geraniol’s protective effects against doxorubicin-mediated kidney dysfunction.

Geraniol Averts Methotrexate-Induced Acute Kidney Injury via Keap1/Nrf2/HO-1 and MAPK/NF-κB Pathways

Objectives: Geraniol, a natural monoterpene, is an essential oil component of many plants. Methotrexate is an anti-metabolite drug, used for cancer and autoimmune conditions; however, clinical uses of methotrexate are limited by its concomitant renal injury. This study investigated the efficacy of geraniol to prevent methotrexate-induced acute kidney injury and via scrutinizing the Keap1/Nrf2/HO-1, P38MAPK/NF-κB and Bax/Bcl2/caspase-3 and -9 pathways. Methods: Male Wister rats were allocated into five groups: control, geraniol (orally), methotrexate (IP), methotrexate and geraniol (100 and 200 mg/kg). Results: Geraniol effectively reduced the serum levels of creatinine, urea and Kim-1 with an increase in the serum level of albumin when compared to the methotrexate-treated group. Geraniol reduced Keap1, escalated Nrf2 and HO-1, enhanced the antioxidant parameters GSH, SOD, CAT and GSHPx and reduced MDA and NO. Geraniol decreased renal P38 MAPK and NF-κB and ameliorated the inflammatory mediators TNF-α, IL-1β, IL-6 and IL-10. Geraniol negatively regulated the apoptotic mediators Bax and caspase-3 and -9 and increased Bcl2. All the biochemical findings were supported by the alleviation of histopathological changes in kidney tissues. Conclusion: The current findings support that co-administration of geraniol with methotrexate may attenuate methotrexate-induced acute kidney injury.

Inhibiting the JNK/ERK signaling pathway with geraniol for attenuating the proliferation of human gastric adenocarcinoma AGS cells

Geraniol, a natural compound found in the essential oils of various aromatic plants, has attracted attention for its probable anticancer effects. The molecular mechanisms of the cell proliferation suppression and apoptosis induction via geraniol in gastric cancer cells (AGS), however, remain unclear. Gastric cancer cells were treated with geraniol, and it was found that the IC₅₀ values were 25 μM/ml, as determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Results showed that 20 and 25 μM geraniol-induced reactive oxygen species (ROS) production (2'-7'dichlorofluorescin diacetate staining) and decreased mitochondrial membrane potential (rhodamine 123 staining) in AGS cells. Then, it effectively inhibited cell growth and induced apoptosis, confirmed through acridine orange/ethidium bromide, 4',6-diamidino-2-phenylindole, and propidium iodide staining and molecular marker analysis in AGS cells. Also, geraniol potently diminished caspase-9, Bax, Bcl-2, and caspase-3 expression in AGS cells. We also evaluated the essential mechanism of the cytotoxic effect of geraniol. Moreover, the present study depicted that geraniol-induced cell death through mitochondrial ROS production and inhibited the phosphorylation form of mitogen-activated protein kinase (p38, MAPK, JNK, and ERK1/2) signaling pathway. Taken together, these results concluded that geraniol has a novel therapeutic property against human stomach cancer.

Insights into gut microbiome and its functional pathways in asthma patients through high-throughput sequencing

Aim: To describe gut microbiome and functional genes of asthma. Patients & methods: Fecal microbiome in controls, asthma patients with and without inhaled corticosteroid (ICS) treatment was determined. Results: Patients with ICS had lower abundance of Alloprevotella, unclassified_f_Lachnospiraceae and Lachnospiraceae_NC2004_group, higher abundance of Sutterella and Sphingomonas than patients without ICS. In all the asthma patients, there are microbial differences in aging distribution, different gender and different asthmatic phenotypes. Asthma patients without ICS treatment had more microbial genes related to geraniol degradation, ethylbenzene degradation and bladder cancer than controls; 15 pathways showed significant difference between asthma patients with and without ICS treatment. Conclusion: We found gut dysbiosis in asthma and different functional pathways associated with both asthma and ICS.

The treatment of asthma using the Chinese Materia Medica

ETHNOPHARMACOLOGICAL RELEVANCE

Asthma is a costly global health problem that negatively influences the quality of life of patients. The Chinese Materia Medica (CMM) contains remedies that have been used for the treatment of asthma for millennia. This article strives to systematically summarize the current research progress so that more comprehensive examinations of various databases related to CMM anti-asthma drugs, can be performed, so as to sequentially provide effective basic data for development and application of anti-asthma drugs based on the CMM.

MATERIALS AND METHODS

The research data published over the past 20 years for asthma treatment based on traditional CMM remedies were retrieved and collected from libraries and online databases (PubMed, ScienceDirect, Elsevier, Spring Link, Web of Science, PubChem Compound, Wan Fang, CNKI, Baidu, and Google Scholar). Information was also added from classic CMM, literature, conference papers on classic herbal formulae, and dissertations (PhD or Masters) based on traditional Chinese medicine.

RESULTS

This review systematically summarizes the experimental studies on the treatment of asthma with CMM, covering the effective chemical components, typical asthma models, important mechanisms and traditional anti-asthma CMM formulae. The therapy value of the CMM for anti-asthma is clarified, and the original data and theoretical research foundation are provided for the development of new anti-asthmatic data and research for the CMM.

CONCLUSIONS

Substantial progress against asthma has been made through relevant experimental research based on the CMM. These advances improved the theoretical basis of anti-asthma drugs for CMM and provided a theoretical basis for the application of a asthma treatment that is unique. By compiling these data, it is expected that the CMM will now contain a clearer mechanism of action and a greater amount of practical data that can be used for future anti-asthma drug research.

Monoterpenes as a perspective for the treatment of seizures: A Systematic Review

BACKGROUND

Epilepsy affects more than 65 million people worldwide. Treatment for epileptic seizures is ineffective and has many adverse effects. For this reason, the search for new therapeutic options capable of filling these limitations is necessary.

HYPOTHESIS/PURPOSE

In this sense, natural products, such as monoterpenes, have been indicated as a new option to control neurological disorders such as epilepsy.

STUDY DESIGN

Therefore, the objective of this study was to review the monoterpenes that have anticonvulsive activity in animal models.

METHODS

The searches were performed in the PubMed, Web of Science and Scopus databases in September, 2020 and compiled studies using monoterpenes as an alternative to seizure. Two independent reviewers performed the study selection, data extraction and methodological quality assessment using the Syrcle tool.

RESULTS

51 articles that described the anticonvulsant activity of 35 monoterpenes were selected with action on the main pharmacological target, including GABAA receptors, glutamate, calcium channels, sodium and potassium. In addition, these compounds are capable of reducing neuronal inflammation and oxidative stress caused by seizure.

CONCLUSION

These compounds stand out as a promising alternative for acting through different pharmacological mechanisms, which may not only reduce seizure, but also promote neuroprotective effect by reducing toxicity in brain regions. However, further studies are needed to determine the mechanism of action and safety assessment of these compounds.

Geraniol targets KV1.3 ion channel and exhibits anti-inflammatory activity in vitro and in vivo

Naturally occurring monoterpenes are known for their various pharmacological activities including anti-inflammation. K_V1.3 ion channel is a voltage-gated potassium channel and has been validated as a drug target for autoimmune and chronic inflammatory diseases like psoriasis. Here we experimentally test the direct interaction between monoterpenes and K_V1.3 ion channel. Our electrophysiological analysis determined that monoterpenes (geraniol, nerol, β-citronellol, citral and linalool) have inhibitory effects on K_V1.3 ion channel. Representatively, geraniol reversibly blocked K_V1.3 currents in a voltage-dependent manner with an IC₅₀ of 490.50 ± 1.04 μM at +40 mV in HEK293T cells. At the effective concentrations, geraniol also inhibited cytokine secretion of activated human T cells, including IL-2, TNF-α and IFN-γ. In an imiquimod-induced psoriasis-like animal model, geraniol administration significantly reduced psoriasis area and severity index scores, ameliorated the deteriorating histopathology and decreased the degree of splenomegaly. Together, our findings not only suggest that monoterpenes may serve as lead molecules for the development of K_V1.3 inhibitors, but also indicate that geraniol could be considered as a promising therapeutic candidate to treat autoimmune diseases.

Chinese medicine Yu-Ping-Feng-San attenuates allergic inflammation by regulating epithelial derived pro-allergic cytokines

This study aimed to investigate the mechanisms of Yu-Ping-Feng-San (YPFS) on attenuating allergic inflammation in the initial stage of atopic dermatitis (AD). AD mouse model was established with fluorescein isothiocyanate (FITC) sensitization and elicitation. Epithelial barrier structure was observed with transmission electron microscope. The populations of dendritic cells (DCs) and group 2 innate lymphoid cells (ILC2s) were detected by flow cytometry. Human immortalized keratinocyte (HaCaT) cells were stimulated with Poly(I:C)/TNF-α in vitro to assessthymic stromal lymphopoietin (TSLP), interleukin (IL)-33 and nuclear factor-κB (NF-κB) levels or expressions by immunofluorescence, enzyme linked immunosorbent assay (ELISA) and western blot. In the initial stage of AD, ear swelling and infiltration of inflammatory cells in ear tissues were markedly attenuated with YPFS treatments. The damaged structures of ear epithelium and the increased levels of Th2-cytokines induced by FITC were significantly rescued in YPFS-treated mice. The production of pro-allergic cytokines, TSLP and IL-33, as well as the cell populations of their target cells DCs and ILC2s were decreased in AD model, respectively. Likewise, the levels of TSLP and IL-33 in Poly(I:C)/TNF-α-stimulated HaCaT cells showed the same results. Lower levels of p-NF-κB were detected with YPFS treatment, and the expressions of TSLP and IL-33 could be further decreased with inhibiting of NF-κB. Therefore, YPFS attenuates allergic inflammation in the initial stage of AD probably through regulating NF-κB-TSLP/IL-33 pathway, which may provide a novel effective target for the prevention and treatment of allergic diseases.

Systemic delivery of mesenchymal stem cells condition media in repeated doses acts as magic bullets in restoring IFN-γ/IL-4 balance in asthmatic rats

AIMS

With respect to recent advantage in stem cell application, given the concern reported previously after stem cell transplantation, mesenchymal stem cell-derived conditioned media (MSC-CM) could be a potential approach to guarantee more safety and efficient outcomes than the current stem cell-based regenerative therapies.

MAIN METHODS

Male rats were assigned into four experimental groups (n = 6); healthy rats (C group), OVA sensitized rats (S group), OVA sensitized rats received a single dose of 50 μl CM intravenously (S group + SD-CM) and OVA sensitized rats received repeated doses of 50 μl CM intravenously (S group + RD-CM). Two weeks post-allergen challenge, the therapeutic effects of systemic administrated CM in single and repeated dosages were investigated by monitoring the transcription of T-bet, GATA-3, IL-4 and IFN-γ genes along with pathological changes in asthmatic lung tissue. IL-4 and IFN-γ levels and IFN-γ/IL-4 ratio were further evaluated in sera.

KEY FINDINGS

Our data revealed that the systemic introduction of CM in repeated dosages could significantly reduce pathological injures in OVA-sensitized rats by the modulation of expression of T-bet and GATA-3 in lung tissues and interleukins levels (p < 0.001 to p < 0.05). In contrary, CM in single dosage did not yield any beneficial effect.

SIGNIFICANCE

Overall, we indicated that systemic administration of CM in repeated dosages, but not in single dose, could be strategic approach in amelioration of asthmatic changes, presumably by the regulating the differentiation of naive CD4 T cells into Th1/Th2 effector cells via modulation of T-bet and GATA-3 expression in OVA-sensitized male rats.

Medicinal properties of terpenes found in Cannabis sativa and Humulus lupulus

Cannabaceae plants Cannabis sativa L. and Humulus lupulus L. are rich in terpenes - both are typically comprised of terpenes as up to 3-5% of the dry-mass of the female inflorescence. Terpenes of cannabis and hops are typically simple mono- and sesquiterpenes derived from two and three isoprene units, respectively. Some terpenes are relatively well known for their potential in biomedicine and have been used in traditional medicine for centuries, while others are yet to be studied in detail. The current, comprehensive review presents terpenes found in cannabis and hops. Terpenes' medicinal properties are supported by numerous in vitro, animal and clinical trials and show anti-inflammatory, antioxidant, analgesic, anticonvulsive, antidepressant, anxiolytic, anticancer, antitumor, neuroprotective, anti-mutagenic, anti-allergic, antibiotic and anti-diabetic attributes, among others. Because of the very low toxicity, these terpenes are already widely used as food additives and in cosmetic products. Thus, they have been proven safe and well-tolerated.

Zein Nanoparticles as Eco-Friendly Carrier Systems for Botanical Repellents Aiming Sustainable Agriculture

Botanical repellents represent one of the main ways of reducing the use of synthetic pesticides and the contamination of soil and hydric resources. However, the poor stability and rapid degradation of these compounds in the environment hinder their effective application in the field. Zein nanoparticles can be used as eco-friendly carrier systems to protect these substances against premature degradation, provide desirable release characteristics, and reduce toxicity in the environment and to humans. In this study, we describe the preparation and characterization of zein nanoparticles loaded with the main constituents of the essential oil of citronella (geraniol and R-citronellal). The phytotoxicity, cytotoxicity, and insect activity of the nanoparticles toward target and nontarget organisms were also evaluated. The botanical formulations showed high encapsulation efficiency (>90%) in the nanoparticles, good physicochemical stability, and effective protection of the repellents against UV degradation. Cytotoxicity and phytotoxicity assays showed that encapsulation of the botanical repellents decreased their toxicity. Repellent activity tests showed that nanoparticles containing the botanical repellents were highly repellent against the Tetranychus urticae Koch mite. This nanotechnological formulation offers a new option for the effective use of botanical repellents in agriculture, reducing toxicity, protecting against premature degradation, and providing effective pest control.

Geraniol Pharmacokinetics, Bioavailability and Its Multiple Effects on the Liver Antioxidant and Xenobiotic-Metabolizing Enzymes

Geraniol is a natural monoterpene showing anti-inflammatory, antioxidant, neuroprotective and anticancer effects. No pharmacokinetic and bioavailability data on geraniol are currently available. We therefore performed a systematic study to identify the permeation properties of geraniol across intestinal cells, and its pharmacokinetics and bioavailability after intravenous and oral administration to rats. In addition, we systematically investigated the potential hepatotoxic effects of high doses of geraniol on hepatic phase I, phase II and antioxidant enzymatic activities and undertook a hematochemical analysis on mice. Permeation studies performed via HPLC evidenced geraniol permeability coefficients across an in vitro model of the human intestinal wall for apical to basolateral and basolateral to apical transport of 13.10 ± 2.3 × 10^-3 and 2.1 ± 0.1⋅× 10^-3 cm/min, respectively. After intravenous administration of geraniol to rats (50 mg/kg), its concentration in whole blood (detected via HPLC) decreased following an apparent pseudo-first order kinetics with a half-life of 12.5 ± 1.5 min. The absolute bioavailability values of oral formulations (50 mg/kg) of emulsified geraniol or fiber-adsorbed geraniol were 92 and 16%, respectively. Following emulsified oral administration, geraniol amounts in the cerebrospinal fluid of rats ranged between 0.72 ± 0.08 μg/mL and 2.6 ± 0.2 μg/mL within 60 min. Mice treated with 120 mg/kg of geraniol for 4 weeks showed increased anti-oxidative defenses with no signs of liver toxicity. CYP450 enzyme activities appeared only slightly affected by the high dosage of geraniol.

Reduction of Asthmatic Parameters by Sea Hare Hydrolysates in a Mouse Model of Allergic Asthma

Sea hare has a variety of biological activities. However, little is known regarding the anti-asthmatic effects of sea hare. This study was performed to identify the effect of sea hare hydrolysates (SHH) on an ovalbumin (OVA)-induced allergic asthma model. The experimental asthma model was sensitized and challenged with OVA. We found that a high-dose of SHH (HSHH) significantly inhibited OVA-induced airway inflammation and mucus production around the airway in lung sections, while low- and medium-dose SHH showed an insignificant effect. In addition, HSHH highly reduced OVA-induced production of interleukin-4, -5, -13, leukotriene D4, E4, and histamine in bronchoalveolar lavage fluid. HSHH decreased the histamine-induced increase in the intracellular Ca²⁺ level and contractions in asthmatic smooth muscle cells. Furthermore, HSHH did not affect the weights of the spleen nor thymus, whereas dexamethasone (DEX), a steroidal anti-inflammatory drug, reduced them. Taken together, these results showed that HSHH reduced asthmatic parameters in a mouse model of allergic asthma, and suggest that SHH could be used as a potential therapeutic agent for asthma.