Limonene-induced activation of A2A adenosine receptors reduces airway inflammation and reactivity in a mouse model of asthma

Terpenes from Cannabis sativa induce antinociception in a mouse model of chronic neuropathic pain via activation of adenosine A2A receptors

ABSTRACT

Terpenes are small hydrocarbon compounds that impart aroma and taste to many plants, including Cannabis sativa. A number of studies have shown that terpenes can produce pain relief in various pain states in both humans and animals. However, these studies were methodologically limited and few established mechanisms of action. In our previous work, we showed that the terpenes geraniol, linalool, β-pinene, α-humulene, and β-caryophyllene produced cannabimimetic behavioral effects via multiple receptor targets. We thus expanded this work to explore the potential antinociception and mechanism of these Cannabis terpenes in a mouse model of chronic pain. We first tested for antinociception by injecting terpenes (200 mg/kg, IP) into male and female CD-1 mice with mouse models of chemotherapy-induced peripheral neuropathy (CIPN) or lipopolysaccharide-induced inflammatory pain, finding that the terpenes produced roughly equal antinociception to 10 mg/kg morphine or 3.2 mg/kg WIN55,212. We further found that none of the terpenes produced reward as measured by conditioned place preference, while low doses of terpene (100 mg/kg) combined with morphine (3.2 mg/kg) produced enhanced antinociception vs either alone. We then used the adenosine A2A receptor (A2AR) selective antagonist istradefylline (3.2 mg/kg, IP) and spinal cord-specific CRISPR knockdown of the A2AR to identify this receptor as the mechanism for terpene antinociception in CIPN. In vitro cAMP and binding studies and in silico modeling studies further suggested that the terpenes act as A2AR agonists. Together these studies identify Cannabis terpenes as potential therapeutics for chronic neuropathic pain and identify a receptor mechanism for this activity.

Eucalyptol, limonene and pinene enteric capsules attenuate airway inflammation and obstruction in lipopolysaccharide-induced chronic bronchitis rat model via TLR4 signaling inhibition

BACKGROUND

Chronic bronchitis (CB), a type of chronic obstructive pulmonary disease (COPD), poses a significant global health burden owing to its high morbidity and mortality rates. Eucalyptol, limonene and pinene enteric capsules (ELPs) are clinically used as expectorants to treat various respiratory diseases, including CB, but their acting mechanisms remain unclear. In this study, we investigated the anti-CB effects of ELP in a rat model of lipopolysaccharide (LPS)-induced CB. The molecular mechanisms underlying its inhibitory effects on airway inflammation were further explored in LPS-stimulated Beas-2B cells.

METHODS

ELP was characterized using gas chromatography. The production of inflammatory mediators in bronchoalveolar lavage fluid (BALF) was determined using an enzyme-linked immunosorbent assay. The expression of MUC5AC, MUC5B, and p-p65 in the lung tissue was measured using immunohistochemical staining. The gene expression of inflammatory mediators was determined using qRT-PCR. The expression levels of the target proteins were detected by western blotting. Nuclear localization of p65 was determined using an immunofluorescence assay.

RESULTS

Compared to the CB model rats, ELP-treated rats showed reduced airway resistance, inflammation, and goblet cell hyperplasia. In BALF, ELP decreased the levels of inflammatory mediators, including TNF-α, IL-6, MIP-1α, and CCL5. ELP also suppressed LPS-induced elevation of MUC5AC, MUC5B, and p-p65 in the lung tissue. The metabolic pathway changes caused by LPS challenge were improved by ELP treatment. In LPS-exposed Beas-2B cells, ELP treatment inhibited the expression of TNFA, IL6, CCL5, MCP1, and MIP2A and decreased the phospho-levels of toll-like receptor 4 (TLR4) signaling-related proteins, including p-p38, p-JNK, p-ERK, p-TBK1, p-IKKα/β, p-IκB, p-p65, and p-c-Jun. ELP also hindered the nuclear translocation of p65, c-Jun, and IRF3.

CONCLUSIONS

This study showed that ELP has a potential therapeutic effect in LPS-induced CB rat model, possibly by suppressing TLR4 signaling. These results justify the clinical use of ELP for the treatment of pulmonary inflammatory diseases.

An Updated Comprehensive Review of Plants and Herbal Compounds with Antiasthmatic Effect

Background

Asthma is a common disease with rising prevalence worldwide, especially in industrialized countries. Current asthma therapy with traditional medicines lacks satisfactory success, hence the patients' search for alternative and complementary treatments for their diseases. Researchers have conducted many studies on plants with antiallergic and antiasthmatic effects in recent decades. Many of these plants are now used in clinics, and searching for their mechanism of action may result in creating new ideas for producing more effective drugs.

Purpose

The goal of this review was to provide a compilation of the findings on plants and their active agents with experimentally confirmed antiasthmatic effects. Study Design and Method. A literature search was conducted from 1986 to November 2023 in Scopus, Springer Link, EMBASE, Science Direct, PubMed, Google Scholar, and Web of Science to identify and report the accumulated knowledge on herbs and their compounds that may be effective in asthma treatment.

Results

The results revealed that 58 plants and 32 herbal extracted compounds had antiasthmatic activity. Also, 32 plants were shown to have anti-inflammatory and antioxidative effects or may act as bronchodilators and potentially have antiasthmatic effects, which must be investigated in future studies.

Conclusion

The ability of herbal medicine to improve asthma symptoms has been confirmed by clinical and preclinical studies, and such compounds may be used as a source for developing new antiasthmatic drugs. Moreover, this review suggests that many bioactive compounds have therapeutic potential against asthma.

Effects of nano-selenium on cecum microbial community and metabolomics in chickens challenged with Ochratoxin A

Introduction

Ochratoxin A (OTA) is a widely distributed mycotoxin. Nano-selenium (Nano-Se) is an emerging form of selenium known for its superior bioavailability, remarkable catalytic efficiency, and robust adsorbing capacity. Despite these characteristics, its impact on the microbial community and metabolomics in the cecum of chickens exposed to OTA has been infrequently investigated. This research examined the microbiota and metabolomic alterations linked to OTA in chickens, with or without Nano-Se present.

Methods

A cohort of 80 healthy chickens at the age of 1 day was randomly distributed into four groups of equal numbers, namely the Se cohort (1 mg/kg Nano-Se), the OTA cohort (50 μg/kg OTA), the OTA-Se cohort (50 μg/kg OTA + 1 mg/kg Nano-Se), and the control group. Each chicken group's caecal microbiome and metabolome were characterized using 16S rRNA sequencing and Liquid chromatography coupled with mass spectrometry (LC-MS) analyses.

Results and discussion

Our results showed that the on day 21, the final body weight was significantly reduced in response to OTA treatments (p < 0.05), the average daily gain in the OTA group was found to be inferior to the other groups (p < 0.01). In addition, Nano-Se supplementation could reduce the jejunum and liver pathological injuries caused by OTA exposure. The 16S rRNA sequencing suggest that Nano-Se supplementation in OTA-exposed chickens mitigated gut microbiota imbalances by promoting beneficial microbiota and suppressing detrimental bacteria. Moreover, untargeted metabolomics revealed a significant difference in caecal metabolites by Nano-Se pretreatment. Collectively, the dataset outcomes highlighted that Nano-Se augmentation regulates intestinal microbiota and associated metabolite profiles, thus influencing critical metabolic pathways, and points to a possible food-additive product.

Abnormal adenosine metabolism of neutrophils inhibits airway inflammation and remodeling in asthma model induced by Aspergillus fumigatus

BACKGROUND

Neutrophils consume a large amount of energy when performing their functions. Compared with other white blood cells, neutrophils contain few mitochondria and mainly rely on glycolysis and gluconeogenesis to produce ATP. The inflammatory site is hypoxic and nutrient poor. Our aim is to study the role of abnormal adenosine metabolism of neutrophils in the asthmatic airway inflammation microenvironment.

METHOD

In this study, an asthma model was established by intratracheal instillation of Aspergillus fumigatus extract in Ecto-5'-Nucleotidase (CD73) gene-knockout and wild-type mice. Multiple analyses from bronchoalveolar lavage fluid (BALF) were used to determine the levels of cytokines and chemokines. Immunohistochemistry was used to detect subcutaneous fibrosis and inflammatory cell infiltration. Finally, adenosine 5'-(α, β-methylene) diphosphate (APCP), a CD73 inhibitor, was pumped subcutaneously before Aspergillus attack to observe the infiltration of inflammatory cells and subcutaneous fibrosis to clarify its therapeutic effect.

RESULT

PAS staining showed that CD73 knockout inhibited pulmonary epithelial cell proliferation and bronchial fibrosis induced by Aspergillus extract. The genetic knockdownof CD73 significantly reduced the production of Th2 cytokines, interleukin (IL)-4, IL-6, IL-13, chemokine (C-C motif) ligand 5 (CCL5), eosinophil chemokine, neutrophil IL-17, and granulocyte colony-stimulating factor (G-CSF). In addition, exogenous adenosine supplementation increased airway inflammation. Finally, the CD73 inhibitor APCP was administered to reduce inflammation and subcutaneous fibrosis.

CONCLUSION

Elevated adenosine metabolism plays an inflammatory role in asthma, and CD73 could be a potential therapeutic target for asthma.

Terpenes from Cannabis sativa Induce Antinociception in Mouse Chronic Neuropathic Pain via Activation of Spinal Cord Adenosine A2A Receptors

Terpenes are small hydrocarbon compounds that impart aroma and taste to many plants, including Cannabis sativa. A number of studies have shown that terpenes can produce pain relief in various pain states in both humans and animals. However, these studies were methodologically limited and few established mechanisms of action. In our previous work, we showed that the terpenes geraniol, linalool, β-pinene, α-humulene, and β-caryophyllene produced cannabimimetic behavioral effects via multiple receptor targets. We thus expanded this work to explore the efficacy and mechanism of these Cannabis terpenes in relieving chronic pain. We first tested for antinociceptive efficacy by injecting terpenes (200 mg/kg, IP) into male and female CD-1 mice with chemotherapy-induced peripheral neuropathy (CIPN) or lipopolysaccharide-induced inflammatory pain, finding that the terpenes produced roughly equal efficacy to 10 mg/kg morphine or 3.2 mg/kg WIN55,212. We further found that none of the terpenes produced reward as measured by conditioned place preference, while low doses of terpene (100 mg/kg) combined with morphine (3.2 mg/kg) produced enhanced antinociception vs. either alone. We then used the adenosine A2A receptor (A2AR) selective antagonist istradefylline (3.2 mg/kg, IP) and spinal cord-specific CRISPR knockdown of the A2AR to identify this receptor as the mechanism for terpene antinociception in CIPN. In vitro cAMP and binding studies and in silico modeling studies further suggested that the terpenes act as A2AR agonists. Together these studies identify Cannabis terpenes as potential therapeutics for chronic neuropathic pain, and identify a receptor mechanism in the spinal cord for this activity.

Exploring the Mechanism of Bergamot Essential Oil against Asthma Based on Network Pharmacology and Experimental Verification

Asthma is a chronic respiratory disease. Bergamot essential oil (BEO) is extracted from the bergamot peel, which is widely used as a medicinal and food plant in China. Modern pharmacological studies have confirmed that BEO has anti-inflammatory properties, suggesting potential in treating asthma. First, the main active ingredients of BEO were detected and analyzed by gas chromatography-mass spectrometry (GC-MS). Network pharmacology methods were used to explore the possible core targets and main pathways of BEO in asthma treatment. Then ovalbumin (OVA)-induced in vivo and lipopolysaccharide (LPS)-induced in vitro models were established to investigate the antiasthmatic effects of BEO. BEO showed a good antiasthmatic effect by improving lung inflammation and inhibiting collagen deposition. Then, enzyme-linked immunosorbent assay (ELISA) and quantitative real-time polymerase chain reaction (qPCR) were used to explore the possible mechanism of BEO in asthma treatment. Furthermore, experimental verification showed that BEO could suppress the release of inflammatory factors in vitro and inhibit the activation of MAPK and JAK-STAT signaling pathways. This study demonstrated the anti-inflammatory effects of BEO against asthma. Moreover, it supplies a theoretical basis for the clinical application of BEO.

Adenosine A2A Receptor in Bone Marrow-Derived Cells Mediated Macrophages M2 Polarization via PPARγ-P65 Pathway in Chronic Hypoperfusion Situation

Background: The role of adenosine A_2A receptor (A_2AR) in the ischemic white matter damage induced by chronic cerebral hypoperfusion remains obscure. Here we investigated the role of A_2AR in the process of macrophage polarizations in the white matter damage induced by chronic cerebral hypoperfusion and explored the involved signaling pathways. Methods: We combined mouse model and macrophage cell line for our study. White matter lesions were induced in A_2AR knockout mice, wild-type mice, and chimeric mice generated by bone marrow cells transplantation through bilateral common carotid artery stenosis. Microglial/macrophage polarization in the corpus callosum was detected by immunofluorescence. For the cell line experiments, RAW264.7 macrophages were treated with the A_2AR agonist CHS21680 or A_2AR antagonist SCH58261 for 30 min and cultured under low-glucose and hypoxic conditions. Macrophage polarization was examined by immunofluorescence. The expression of peroxisome proliferator activated receptor gamma (PPARγ) and transcription factor P65 was examined by western blotting and real-time polymerase chain reaction (RT-PCR). Inflammatory cytokine factors were assessed by enzyme-linked immunosorbent assay (ELISA) and RT-PCR. Results: Both global A_2AR knockout and inactivation of A_2AR in bone marrow-derived cells enhanced M1 marker expression in chronic ischemic white matter lesions. Under low-glucose and hypoxic conditions, CGS21680 treatment promoted macrophage M2 polarization, increased the expression of PPARγ, P65, and interleukin-10 (IL-10) and suppressed the expression of tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β). The CGS21680-induced upregulation of P65 and IL-10 was abolished in macrophages upon PPARγ knockdown. The downregulation of TNF-α and IL-1β by CGS21680 was less affected by PPARγ knockdown. Conclusions: In the cerebral hypoperfusion induced white matter damage, A_2AR signaling in bone marrow-derived cells induces macrophage M2 polarization and increases the expression of the anti-inflammatory factor IL-10 via the PPARγ-P65 pathway, both of which might explain its neuroprotective effect.

Establishment and validation of a logistic regression model for prediction of septic shock severity in children

Background

Septic shock is the most severe complication of sepsis, and is a major cause of childhood mortality, constituting a heavy public health burden.

Methods

We analyzed the gene expression profiles of septic shock and control samples from the Gene Expression Omnibus (GEO). Four differentially expressed genes (DEGs) from survivor and control groups, non-survivor and control groups, and survivor and non-survivor groups were selected. We used data about these genes to establish a logistic regression model for predicting the survival of septic shock patients.

Results

Leave-one-out cross validation and receiver operating characteristic (ROC) analysis indicated that this model had good accuracy. Differential expression and Gene Set Enrichment Analysis (GSEA) between septic shock patients stratified by prediction score indicated that the systemic lupus erythematosus pathway was activated, while the limonene and pinene degradation pathways were inactivated in the high score group.

Conclusions

Our study provides a novel approach for the prediction of the severity of pathology in septic shock patients, which are significant for personalized treatment as well as prognostic assessment.

Supplementary Information

The online version contains supplementary material available at 10.1186/s41065-021-00206-9.

Analgesic Potential of Terpenes Derived from Cannabis sativa

Pain prevalence among adults in the United States has increased 25% over the past two decades, resulting in high health-care costs and impacts to patient quality of life. In the last 30 years, our understanding of pain circuits and (intra)cellular mechanisms has grown exponentially, but this understanding has not yet resulted in improved therapies. Options for pain management are limited. Many analgesics have poor efficacy and are accompanied by severe side effects such as addiction, resulting in a devastating opioid abuse and overdose epidemic. These problems have encouraged scientists to identify novel molecular targets and develop alternative pain therapeutics. Increasing preclinical and clinical evidence suggests that cannabis has several beneficial pharmacological activities, including pain relief. Cannabis sativa contains more than 500 chemical compounds, with two principle phytocannabinoids, Δ9-tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD). Beyond phytocannabinoids, more than 150 terpenes have been identified in different cannabis chemovars. Although the predominant cannabinoids, Δ9-THC and CBD, are thought to be the primary medicinal compounds, terpenes including the monoterpenes β-myrcene, α-pinene, limonene, and linalool, as well as the sesquiterpenes β-caryophyllene and α-humulene may contribute to many pharmacological properties of cannabis, including anti-inflammatory and antinociceptive effects. The aim of this review is to summarize our current knowledge about terpene compounds in cannabis and to analyze the available scientific evidence for a role of cannabis-derived terpenes in modern pain management. SIGNIFICANCE STATEMENT: Decades of research have improved our knowledge of cannabis polypharmacy and contributing phytochemicals, including terpenes. Reform of the legal status for cannabis possession and increased availability (medicinal and recreational) have resulted in cannabis use to combat the increasing prevalence of pain and may help to address the opioid crisis. Better understanding of the pharmacological effects of cannabis and its active components, including terpenes, may assist in identifying new therapeutic approaches and optimizing the use of cannabis and/or terpenes as analgesic agents.

Adenosine Signaling in Mast Cells and Allergic Diseases

Adenosine is a nucleoside involved in the pathogenesis of allergic diseases. Its effects are mediated through its binding to G protein-coupled receptors: A1, A2a, A2b and A3. The receptors differ in the type of G protein they recruit, in the effect on adenylyl cyclase (AC) activity and the downstream signaling pathway triggered. Adenosine can produce both an enhancement and an inhibition of mast cell degranulation, indicating that adenosine effects on these receptors is controversial and remains to be clarified. Depending on the study model, A1, A2b, and A3 receptors have shown anti- or pro-inflammatory activity. However, most studies reported an anti-inflammatory activity of A2a receptor. The precise knowledge of the adenosine mechanism of action may allow to develop more efficient therapies for allergic diseases by using selective agonist and antagonist against specific receptor subtypes.

Can limonene be a possible candidate for evaluation as an agent or adjuvant against infection, immunity, and inflammation in COVID-19?

Coronavirus disease (COVID-19) caused by novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an ongoing pandemic and presents a public health emergency. It has affected millions of people and continues to affect more, despite the tremendous social preventive measures. The therapeutic strategy relies on suppressing infectivity and inflammation, along with immune modulation. The identification of candidate drugs effective for COVID-19 is crucial, thus many natural products including phytochemicals are also being proposed for repurposing and evaluated for their potential in COVID-19. Among numerous phytochemicals, limonene (LMN), a dietary terpene of natural origin has been recently showed to target viral proteins in the in-silico studies. LMN is one of the main compounds identified in many citrus plants, available and accessible in diets and well-studied for its therapeutic benefits. Due to dietary nature, relative safety and efficacy along with favorable physicochemical properties, LMN has been suggested to be a fascinating candidate for further investigation in COVID-19. LMN showed to modulate numerous signaling pathways and inhibits inflammatory mediators, including cytokines, chemokines, adhesion molecules, prostanoids, and eicosanoids. We hypothesized that given the pathogenesis of COVID-19 involving infection, inflammation, and immunity, LMN may have potential to limit the severity and progression of the disease owing to its immunomodulatory, anti-inflammatory, and antiviral properties. The present article discusses the possibilities of LMN in SARS-CoV-2 infections based on its immunomodulatory, anti-inflammatory, and antiviral properties. Though, the suggestion on the possible use of LMN in COVID-19 remains inconclusive until the in-silico effects confirmed in the experimental studies and further proof of the concept studies. The candidature of LMN in COVID-19 treatment somewhat appear speculative but cannot be overlooked provided favorable physiochemical and druggable properties. The safety and efficacy of LMN are necessary to be established in preclinical and clinical studies before making suggestions for use in humans.