CB2 receptors regulate natural killer cells that limit allergic airway inflammation in a murine model of asthma

Cannabidiol as an immune modulator: A comprehensive review

Cannabidiol (CBD), a non-psychoactive phytocannabinoid derived from Cannabis sativa, has emerged as a promising therapeutic agent due to its diverse pharmacological properties, including potent anti-inflammatory, neuroprotective, and immunomodulatory effects. CBD modulates immune responses, including the regulation of T cell activity, induction of macrophage apoptosis, suppression of pro-inflammatory cytokines, and modulation of signaling pathways involved in inflammation and immune homeostasis. A comprehensive literature search was conducted using PubMed, Scopus, and Web of Science databases to identify relevant preclinical and clinical studies on CBD's immunomodulatory effects. Preclinical and clinical studies demonstrate its efficacy in treating autoimmune diseases such as Type 1 diabetes, multiple sclerosis, rheumatoid arthritis, and inflammatory bowel disease, along with its potential in neuropathic pain and cancer therapy. Recent advancements in nanotechnology-based delivery systems have further enhanced CBD's therapeutic potential by improving its solubility, bioavailability, and targeted delivery, enabling innovative approaches for wound healing, inflammation management, and cancer treatment. However, challenges such as variability in immune responses, limited long-term safety data, and potential drug-drug interactions persist. This review comprehensively examines CBD's pharmacokinetics, pharmacodynamics, and immunomodulatory mechanisms, highlighting its clinical potential, existing limitations, and future directions in advancing its integration into precision medicine and immune regulation.

Decoding innate lymphoid cells and innate-like lymphocytes in asthma: pathways to mechanisms and therapies

Asthma is a chronic inflammatory lung disease driven by a complex interplay between innate and adaptive immune components. Among these, innate lymphoid cells (ILCs) and innate-like lymphocytes have emerged as crucial players in shaping the disease phenotype. Within the ILC family, group 2 ILCs (ILC2s), in particular, contribute significantly to type 2 inflammation through their rapid production of cytokines such as IL-5 and IL-13, promoting airway eosinophilia and airway hyperreactivity. On the other hand, innate-like lymphocytes such as invariant natural killer T (iNKT) cells can play either pathogenic or protective roles in asthma, depending on the stimuli and lung microenvironment. Regulatory mechanisms, including cytokine signaling, metabolic and dietary cues, and interactions with other immune cells, play critical roles in modulating their functions. In this review, we highlight current findings on the role of ILCs and innate-like lymphocytes in asthma development and pathogenesis. We also examine the underlying mechanisms regulating their function and their interplay with other immune cells. Finally, we explore current therapies targeting these cells and their effector cytokines for asthma management.

Natural killer cells in the lung: novel insight and future challenge in the airway diseases

Natural killer (NK) cells are innate lymphoid cells which are present in the lung as circulating and resident cells. They are key players both in airway surveillance and in crosstalk with (COPD) pathogenesis, and they seem to contribute to the development of bronchiectasis. In asthma, NK cell dysfunction was observed mainly in severe forms, and it can lead to a biased type-2 immune response and failure in the resolution of eosinophilic inflammation that characterise both allergic and eosinophilic phenotypes. Moreover, aberrant NK cell functions may interfere with antimicrobial immune response contributing to the frequency and severity of virus-induced exacerbations. In COPD, lung NK cells exhibit increased cytotoxicity against lung epithelium contributing to lung tissue destruction and emphysema. This cell destruction may be exacerbated by viral infections and cigarette smoke exposure through NKG2D-dependent detection of cellular stress. Lastly, in bronchiectasis, the airway NK cells might both promote neutrophil survival following stimulation by proinflammatory cytokines and promote neutrophil apoptosis. Systemic steroid treatment seemingly compromises NK activity, while biologic treatment with benralizumab could enhance NK cell proliferation, maturation and activation. This narrative review gives an overview of NK cells in airway diseases focusing on pathophysiological and clinical implications. Together, our findings emphasise the pleiotropic role of NK cells in airway diseases underscoring their possible implications as to therapeutical approaches.

CB2 stimulation of adipose resident ILC2s orchestrates immune balance and ameliorates type 2 diabetes mellitus

Development of type 2 diabetes mellitus (T2DM) is associated with low-grade chronic type 2 inflammation and disturbance of glucose homeostasis. Group 2 innate lymphoid cells (ILC2s) play a critical role in maintaining adipose homeostasis via the production of type 2 cytokines. Here, we demonstrate that CB2, a G-protein-coupled receptor (GPCR) and member of the endocannabinoid system, is expressed on both visceral adipose tissue (VAT)-derived murine and human ILC2s. Moreover, we utilize a combination of ex vivo and in vivo approaches to explore the functional and therapeutic impacts of CB2 engagement on VAT ILC2s in a T2DM model. Our results show that CB2 stimulation of ILC2s protects against insulin-resistance onset, ameliorates glucose tolerance, and reverses established insulin resistance. Our mechanistic studies reveal that the therapeutic effects of CB2 are mediated through activation of the AKT, ERK1/2, and CREB pathways on ILC2s. The results reveal that the CB2 agonist can serve as a candidate for the prevention and treatment of T2DM.

The Impact of the CB2 Cannabinoid Receptor in Inflammatory Diseases: An Update

The emergence of inflammatory diseases is a heavy burden on modern societies. Cannabis has been used for several millennia to treat inflammatory disorders such as rheumatism or gout. Since the characterization of cannabinoid receptors, CB1 and CB2, the potential of cannabinoid pharmacotherapy in inflammatory conditions has received great interest. Several studies have identified the importance of these receptors in immune cell migration and in the production of inflammatory mediators. As the presence of the CB2 receptor was documented to be more predominant in immune cells, several pharmacological agonists and antagonists have been designed to treat inflammation. To better define the potential of the CB2 receptor, three online databases, PubMed, Google Scholar and clinicaltrial.gov, were searched without language restriction. The full texts of articles presenting data on the endocannabinoid system, the CB2 receptor and its role in modulating inflammation in vitro, in animal models and in the context of clinical trials were reviewed. Finally, we discuss the clinical potential of the latest cannabinoid-based therapies in inflammatory diseases.

Cannabinoid receptor 2 as a regulator of inflammation induced oleoylethanolamide in eosinophilic asthma

BACKGROUND

Oleoylethanolamide (OEA), an endogenously generated cannabinoid-like compound, has been reported to be increased in patients with severe asthma and aspirin-exacerbated respiratory disease. Recruitment of activated eosinophils in the airways is a hallmark of bronchial asthma.

OBJECTIVE

We explored the direct contribution of cannabinoid receptor 2 (CB2), a cognate receptor of OEA, which induces eosinophil activation in vitro and in vivo.

METHODS

We investigated OEA signaling in the eosinophilic cell line dEol-1 in peripheral blood eosinophils from people with asthma. In order to confirm whether eosinophil activation by OEA is CB2 dependent or not, CB2 small interfering RNA and the CB2 antagonist SR144528 were used. The numbers of airway inflammatory cells and the levels of cytokines were measured in bronchoalveolar lavage fluid, and airway hyperresponsiveness was examined in the BALB/c mice.

RESULTS

CB2 expression was increased after OEA treatment in both peripheral blood eosinophils and dEol-1 cells. It was also elevated after OEA-induced recruitment of eosinophils to the lungs in vivo. However, SR144528 treatment reduced the activation of peripheral blood eosinophils from asthmatic patients. Furthermore, CB2 knockdown decreased the activation of dEol-1 cells and the levels of inflammatory and type 2 cytokines. SR144528 treatment alleviated airway hyperresponsiveness and eosinophil recruitment to the lungs in vivo.

CONCLUSION

CB2 may contribute to the pathogenesis of eosinophilic asthma. Our results provide new insight into the molecular mechanism of signal transduction by OEA in eosinophilic asthma.

The role of hormones in ILC2-driven allergic airway inflammation

Group 2 innate lymphoid cells (ILC2s) are a type of innate immune cells that produce a large amount of IL-5 and IL-13 and two cytokines that are crucial for various processes such as allergic airway inflammation, tissue repair and tissue homeostasis. It is known that damaged epithelial-derived alarmins, such as IL-33, IL-25 and thymic stromal lymphopoietin (TSLP), are the predominant ILC2 activators that mediate the production of type 2 cytokines. In recent years, abundant studies have found that many factors can regulate ILC2 development and function. Hormones synthesized by the body's endocrine glands or cells play an important role in immune response. Notably, ILC2s express hormone receptors and their proliferation and function can be modulated by multiple hormones during allergic airway inflammation. Here, we summarize the effects of multiple hormones on ILC2-driven allergic airway inflammation and discuss the underlying mechanisms and potential therapeutic significance.

Cannabinoid receptor 2 signal promotes type 2 immunity in the lung

Type 2 immunity in the lung protects against pathogenic infection and facilitates tissue repair, but its dysregulation may lead to severe human diseases. Notably, cannabis usage for medical or recreational purposes has increased globally. However, the potential impact of the cannabinoid signal on lung immunity is incompletely understood. Here, we report that cannabinoid receptor 2 (CB2) is highly expressed in group 2 innate lymphoid cells (ILC2s) of mouse and human lung tissues. Of importance, the CB2 signal enhances the IL-33-elicited immune response of ILC2s. In addition, the chemogenetic manipulation of inhibitory G proteins (Gi) downstream of CB2 produces a similarly promotive effect. Conversely, the genetic deletion of CB2 mitigates the IL-33-elicited type 2 immunity in the lung. Also, such ablation of the CB2 signal ameliorates papain-induced tissue inflammation. Together, these results have elucidated a critical aspect of the CB2 signal in lung immunity, implicating its potential involvement in pulmonary diseases.

Natural killer cells in the lung: potential role in asthma and virus-induced exacerbation?

Asthma is a chronic inflammatory airway disorder whose pathophysiological and immunological mechanisms are not completely understood. Asthma exacerbations are mostly driven by respiratory viral infections and characterised by worsening of symptoms. Despite current therapies, asthma exacerbations can still be life-threatening. Natural killer (NK) cells are innate lymphoid cells well known for their antiviral activity and are present in the lung as circulating and resident cells. However, their functions in asthma and its exacerbations are still unclear. In this review, we will address NK cell activation and functions, which are particularly relevant for asthma and virus-induced asthma exacerbations. Then, the role of NK cells in the lungs at homeostasis in healthy individuals will be described, as well as their functions during pulmonary viral infections, with an emphasis on those associated with asthma exacerbations. Finally, we will discuss the involvement of NK cells in asthma and virus-induced exacerbations and examine the effect of asthma treatments on NK cells.

Effects of Cannabidiol on Innate Immunity: Experimental Evidence and Clinical Relevance

Cannabidiol (CBD) is the main non-psychotropic cannabinoid derived from cannabis (Cannabis sativa L., fam. Cannabaceae). CBD has received approval by the Food and Drug Administration (FDA) and European Medicines Agency (EMA) for the treatment of seizures associated with Lennox-Gastaut syndrome or Dravet syndrome. However, CBD also has prominent anti-inflammatory and immunomodulatory effects; evidence exists that it could be beneficial in chronic inflammation, and even in acute inflammatory conditions, such as those due to SARS-CoV-2 infection. In this work, we review available evidence concerning CBD's effects on the modulation of innate immunity. Despite the lack so far of clinical studies, extensive preclinical evidence in different models, including mice, rats, guinea pigs, and even ex vivo experiments on cells from human healthy subjects, shows that CBD exerts a wide range of inhibitory effects by decreasing cytokine production and tissue infiltration, and acting on a variety of other inflammation-related functions in several innate immune cells. Clinical studies are now warranted to establish the therapeutic role of CBD in diseases with a strong inflammatory component, such as multiple sclerosis and other autoimmune diseases, cancer, asthma, and cardiovascular diseases.

The Therapeutic Potential of the Endocannabinoid System in Age-Related Diseases

The endocannabinoid system (ECS) dynamically regulates many aspects of mammalian physiology. ECS has gained substantial interest since growing evidence suggests that it also plays a major role in several pathophysiological conditions due to its ability to modulate various underlying mechanisms. Furthermore, cannabinoids, as components of the cannabinoid system (CS), have proven beneficial effects such as anti-inflammatory, immunomodulatory, neuromodulatory, antioxidative, and cardioprotective effects. In this comprehensive review, we aimed to describe the complex interaction between CS and most common age-related diseases such as neuro-degenerative, oncological, skeletal, and cardiovascular disorders, together with the potential of various cannabinoids to ameliorate the progression of these disorders. Since chronic inflammation is postulated as the pillar of all the above-mentioned medical conditions, we also discuss in this paper the potential of CS to ameliorate aging-associated immune system dysregulation.

Cannabinoid receptor 2 engagement promotes group 2 innate lymphoid cell expansion and enhances airway hyperreactivity

BACKGROUND

Cannabinoids modulate the activation of immune cells and physiologic processes in the lungs. Group 2 innate lymphoid cells (ILC2s) are central players in type 2 asthma, but how cannabinoids modulate ILC2 activation remains to be elucidated.

OBJECTIVE

Our goal was to investigate the effects of cannabinoids on ILC2s and their role in asthma.

METHODS

A combination of cannabinoid receptor (CB)2 knockout (KO) mice, CB2 antagonist and agonist were used in the mouse models of IL-33, IL-25, and Alternaria alternata ILC2-dependent airway inflammation. RNA sequencing was performed to assess transcriptomic changes in ILC2s, and humanized mice were used to assess the role of CB2 signaling in human ILC2s.

RESULTS

We provide evidence that CB2 signaling in ILC2s is important for the development of ILC2-driven airway inflammation in both mice and human. We showed that both naive and activated murine pulmonary ILC2s express CB2. CB2 signaling did not affect ILC2 homeostasis at steady state, but strikingly it stimulated ILC2 proliferation and function upon activation. As a result, ILC2s lacking CB2 induced lower lung inflammation, as we made similar observations using a CB2 antagonist. Conversely, CB2 agonism remarkably exacerbated ILC2-driven airway hyperreactivity and lung inflammation. Mechanistically, transcriptomic and protein analysis revealed that CB2 signaling induced cyclic adenosine monophosphate-response element binding protein (CREB) phosphorylation in ILC2s. Human ILC2s expressed CB2, as CB2 antagonism and agonism showed opposing effects on ILC2 effector function and development of airway hyperreactivity in humanized mice.

CONCLUSION

Collectively, our results define CB2 signaling in ILC2s as an important modulator of airway inflammation.

Expression and Functions of the CB2 Receptor in Human Leukocytes

The cannabinoid CB₂ receptor was cloned from the promyeloid cell line HL-60 and is notably expressed in most, if not all leukocyte types. This relatively restricted localization, combined to the absence of psychotropic effects following its activation, make it an attractive drug target for inflammatory and autoimmune diseases. Therefore, there has been an increasing interest in the past decades to identify precisely which immune cells express the CB₂ receptor and what are the consequences of such activation. Herein, we provide new data on the expression of both CB₁ and CB₂ receptors by human blood leukocytes and discuss the impact of CB₂ receptor activation in human leukocytes. While the expression of the CB₂ mRNA can be detected in eosinophils, neutrophils, monocytes, B and T lymphocytes, this receptor is most abundant in human eosinophils and B lymphocytes. We also review the evidence obtained from primary human leukocytes and immortalized cell lines regarding the regulation of their functions by the CB₂ receptor, which underscore the urgent need to deepen our understanding of the CB₂ receptor as an immunoregulator in humans.

Effects of non-steroidal anti-inflammatory drugs and other eicosanoid pathway modifiers on antiviral and allergic responses: EAACI task force on eicosanoids consensus report in times of COVID-19

Non‐steroidal anti‐inflammatory drugs (NSAIDs) and other eicosanoid pathway modifiers are among the most ubiquitously used medications in the general population. Their broad anti‐inflammatory, antipyretic, and analgesic effects are applied against symptoms of respiratory infections, including SARS‐CoV‐2, as well as in other acute and chronic inflammatory diseases that often coexist with allergy and asthma. However, the current pandemic of COVID‐19 also revealed the gaps in our understanding of their mechanism of action, selectivity, and interactions not only during viral infections and inflammation, but also in asthma exacerbations, uncontrolled allergic inflammation, and NSAIDs‐exacerbated respiratory disease (NERD). In this context, the consensus report summarizes currently available knowledge, novel discoveries, and controversies regarding the use of NSAIDs in COVID‐19, and the role of NSAIDs in asthma and viral asthma exacerbations. We also describe here novel mechanisms of action of leukotriene receptor antagonists (LTRAs), outline how to predict responses to LTRA therapy and discuss a potential role of LTRA therapy in COVID‐19 treatment. Moreover, we discuss interactions of novel T2 biologicals and other eicosanoid pathway modifiers on the horizon, such as prostaglandin D2 antagonists and cannabinoids, with eicosanoid pathways, in context of viral infections and exacerbations of asthma and allergic diseases. Finally, we identify and summarize the major knowledge gaps and unmet needs in current eicosanoid research.

“The Two Sides of the Same Coin”—Medical Cannabis, Cannabinoids and Immunity: Pros and Cons Explained

Cannabis, as a natural medicinal remedy, has long been used for palliative treatment to alleviate the side effects caused by diseases. Cannabis-based products isolated from plant extracts exhibit potent immunoregulatory properties, reducing chronic inflammatory processes and providing much needed pain relief. They are a proven effective solution for treatment-based side effects, easing the resulting symptoms of the disease. However, we discuss the fact that cannabis use may promote the progression of a range of malignancies, interfere with anti-cancer immunotherapy, or increase susceptibility to viral infections and transmission. Most cannabis preparations or isolated active components cause an overall potent immunosuppressive impact among users, posing a considerable hazard to patients with suppressed or compromised immune systems. In this review, current knowledge and perceptions of cannabis or cannabinoids and their impact on various immune-system components will be discussed as the “two sides of the same coin” or “double-edged sword”, referring to something that can have both favorable and unfavorable consequences. We propose that much is still unknown about adverse reactions to its use, and its integration with medical treatment should be conducted cautiously with consideration of the individual patient, effector cells, microenvironment, and the immune system.

The cannabinoid WIN55212-2 impairs peanut allergic sensitization and promotes the generation of allergen-specific regulatory T cells

BACKGROUND

Cannabinoids are lipid-derived mediators with anti-inflammatory properties in different diseases. WIN55212-2, a non-selective synthetic cannabinoid, reduces immediate anaphylactic reactions in a mouse model of peanut allergy, but its capacity to prevent peanut allergic sensitization and the underlying mechanisms remains largely unknown.

OBJECTIVE

To investigate the capacity of WIN55212-2 to immunomodulate peanut-stimulated human dendritic cells (DCs) and peanut allergic sensitization in mice.

METHODS

Surface markers and cytokines were quantified by flow cytometry, ELISA and qPCR in human monocyte-derived DCs (hmoDCs) and T cell cocultures after stimulation with peanut alone or in the presence of WIN55212-2. Mice were epicutaneously sensitized with peanut alone or peanut/WIN55212-2. After peanut challenge, drop in body temperature, hematocrit, clinical symptoms, peanut-specific antibodies in serum and FOXP3⁺ regulatory (Treg) cells in spleen and lymph nodes were quantified. Splenocytes were stimulated in vitro with peanut to analyse allergen-specific T cell responses.

RESULTS

WIN55212-2 reduced peanut-induced hmoDC activation and promoted the generation of CD4⁺ CD127^- CD25⁺ FOXP3⁺ Treg cells, while reducing the induction of IL-5-producing T cells. In vivo, WIN55212-2 impaired the peanut-induced migration of DCs to lymph nodes and their maturation. WIN55212-2 significantly reduced the induction of peanut-specific IgE and IgG₁ antibodies in serum during epicutaneous peanut sensitization, reduced the clinical symptoms score upon peanut challenge and promoted the generation of allergen-specific FOXP3⁺ Treg cells.

CONCLUSIONS

The synthetic cannabinoid WIN55212-2 interferes with peanut sensitization and promotes tolerogenic responses, which might well pave the way for the development of novel prophylactic and therapeutic strategies for peanut allergy.

Innate-like Lymphocytes and Innate Lymphoid Cells in Asthma

Asthma is a chronic pulmonary disease, highly associated with immune disorders. The typical symptoms of asthma include airway hyperresponsiveness (AHR), airway remodeling, mucus overproduction, and airflow limitation. The etiology of asthma is multifactorial and affected by genetic and environmental factors. Increasing trends toward dysbiosis, smoking, stress, air pollution, and a western lifestyle may account for the increasing incidence of asthma. Based on the presence or absence of eosinophilic inflammation, asthma is mainly divided into T helper 2 (Th2) and non-Th2 asthma. Th2 asthma is mediated by allergen-specific Th2 cells, and eosinophils activated by Th2 cells via the secretion of interleukin (IL)-4, IL-5, and IL-13. Different from Th2 asthma, non-Th2 asthma shows little eosinophilic inflammation, resists to corticosteroid treatment, and occurs mainly in severe asthmatic patients. Previous studies of asthma primarily focused on the function of Th2 cells, but, with the discovery of non-Th2 asthma and the involvement of innate lymphoid cells (ILCs) in the pathogenesis of asthma, tissue-resident innate immune cells in the lung have become the focus of attention in asthma research. Currently, innate-like lymphocytes (ILLs) and ILCs as important components of the innate immune system in mucosal tissues are reportedly involved in the pathogenesis of or protection against both Th2 and non-Th2 asthma. These findings of the functions of different subsets of ILLs and ILCs may provide clues for the treatment of asthma.

The Therapeutic Potential of Cannabis in Counteracting Oxidative Stress and Inflammation

Significant growth of interest in cannabis (Cannabis sativa L.), especially its natural anti-inflammatory and antioxidative properties, has been observed recently. This narrative review aimed to present the state of the art of research concerning the anti-inflammatory activity of all classes of cannabinoids published in the last five years. Multimodal properties of cannabinoids include their involvement in immunological processes, anti-inflammatory, and antioxidative effects. Cannabinoids and non-cannabinoid compounds of cannabis proved their anti-inflammatory effects in numerous animal models. The research in humans is missing, and the results are unconvincing. Although preclinical evidence suggests cannabinoids are of value in treating chronic inflammatory diseases, the clinical evidence is scarce, and further well-designed clinical trials are essential to determine the prospects for using cannabinoids in inflammatory conditions.

Air pollution from traffic during pregnancy impairs newborn's cord blood immune cells: The NELA cohort

BACKGROUND

Hazards of traffic-related air pollution (TRAP) on the developing immune system are poorly understood. We sought to investigate the effects of prenatal exposure to TRAP on cord blood immune cell distributions; and to identify gestational windows of susceptibility.

METHODS

In-depth immunophenotyping of cord blood leukocyte and lymphocyte subsets was performed by flow cytometry in 190 newborns embedded in the Nutrition in Early Life and Asthma (NELA) birth cohort (2015-2018). Long-term (whole pregnancy and trimesters) and short-term (15-days before delivery) residential exposures to traffic-related nitrogen dioxide (NO₂), particulate matter (PM_2.5 and PM₁₀), and ozone (O₃) were estimated using dispersion/chemical transport modelling. Associations between TRAP concentrations and cord blood immune cell counts were assessed using multivariate Poisson regression models.

RESULTS

Mean number of natural killer (NK) cells decreased 15% in relation to higher NO₂ concentrations (≥36.4 μg/m3) during whole pregnancy (incidence relative risk (IRR), 0.85; 95% CI, 0.72, 0.99), with stronger associations in the first trimester. Higher PM_2.5 concentrations (≥13.3 μg/m³) during whole pregnancy associated with a reduced mean number of cytotoxic T cells (IRR, 0.88; 95% CI, 0.78, 0.99). Newborns exposed to higher PM₁₀ (≥23.6 μg/m³) and PM_2.5 concentrations during the first and third trimester showed greater mean number of helper T type 1 (Th1) cells (P < 0.05). Decreased number of regulatory T (Treg) cells was associated with greater short-term NO₂ (IRR, 0.90; 95% CI, 0.80, 1.01) and PM₁₀ (IRR, 0.88; 95% CI, 0.77, 0.99) concentrations.

CONCLUSIONS

Prenatal exposure to TRAP, particularly in early and late gestation, impairs fetal immune system development through disturbances in cord blood leukocyte and lymphocyte distributions.

Oleoylethanolamide induces eosinophilic airway inflammation in bronchial asthma

Asthma is a chronic eosinophilic inflammatory disease with an increasing prevalence worldwide. Endocannabinoids are known to have immunomodulatory biological effects. However, the contribution of oleoylethanolamide (OEA) to airway inflammation remains to be elucidated. To investigate the effect of OEA, the expression of proinflammatory cytokines was measured by RT-qPCR and ELISA in airway epithelial (A549) cells. The numbers of airway inflammatory cells and cytokine levels in bronchoalveolar lavage fluid, airway hyperresponsiveness, and type 2 innate lymphoid cells (ILC2s) were examined in BALB/c mice after 4 days of OEA treatment. Furthermore, eosinophil activation after OEA treatment was evaluated by measuring cellular CD69 levels in eosinophils from human peripheral eosinophils using flow cytometry. OEA induced type 2 inflammatory responses in vitro and in vivo. OEA increased the levels of proinflammatory cytokines, such as IL-6, IL-8, and IL-33, in A549 cells. In addition, it also induced eosinophilic inflammation, the production of IL-4, IL-5, IL-13, and IL-33 in bronchoalveolar lavage fluid, and airway hyperresponsiveness. OEA increased the numbers of IL-5- or IL-13-producing ILC2s in a mouse model. Finally, we confirmed that OEA increased CD69 expression (an eosinophil activation marker) on purified eosinophils from patients with asthma compared to those from healthy controls. OEA may play a role in the pathogenesis of asthma by activating ILC2s and eosinophils.

Selective activation of cannabinoid receptor 2 regulates Treg/Th17 balance to ameliorate neutrophilic asthma in mice

Background

The cannabinoid receptor 2 (CNR2) plays a critical role in relieving asthma, with the mechanism still unclear. We aimed to investigate the mechanism of the CNR2 agonist (β-caryophyllene, β-Car) in regulating the balance of regulatory T cells (Treg) and T helper cell 17 (Th17) and thus its role in asthma.

Methods

The study group of 50 pathogen-free female BALB/c mice were randomly divided at 6–8 weeks old into five groups of Control, Asthma, Asthma + β-Car (10 mg/kg), Asthma + β-Car + SR144528 (specific CNR2 antagonist, 3 mg/kg), and Asthma + β-Car + CMD178 (inhibitor of Treg cell, 10 mg/kg). ELISA was conducted to evaluate the main inflammatory cytokines [interleukin (IL)-6, IL-8, and tumor necrosis factor-α], and those secreted by Treg (transforming growth factor-β and IL-10), and Th17 (IL-17A and IL-22). Markers of Treg and Th17 cells were assessed by flow cytometry. In vitro, the CD4⁺ T cells were sorted and directed to differentiate to Treg and Th17 cells. The expression levels of CNR2, STAT5 and JNK1/2 were investigated by western blot and immunofluorescence assay.

Results

β-Car relieved neutrophilic asthma severity in mice by elevating the marker genes’ expression of Treg and inhibiting those of Th17, causing an increased proportion of Treg to Th17. β-Car also promoted the directed differentiation of CD4⁺ T cells into Treg, but not Th17. Activation of the CNR2 regulated the Treg/Th17 balance and relieved neutrophilic asthma possibly through promotion of phosphorylation of STAT5 and JNK1/2.

Conclusions

The effect of the selective CNR2 agonist activating STAT5 and JNK1/2 signaling was to change the Treg/Th17 balance and reduce the inflammatory reaction, thus ameliorating neutrophilic asthma in a mouse model.

Cannabinoids and Inflammations of the Gut-Lung-Skin Barrier

Recent studies have identified great similarities and interferences between the epithelial layers of the digestive tract, the airways and the cutaneous layer. The relationship between these structures seems to implicate signaling pathways, cellular components and metabolic features, and has led to the definition of a gut-lung-skin barrier. Inflammation seems to involve common features in these tissues; therefore, analyzing the similarities and differences in the modulation of its biomarkers can yield significant data promoting a better understanding of the particularities of specific signaling pathways and cellular effects. Cannabinoids are well known for a wide array of beneficial effects, including anti-inflammatory properties. This paper aims to explore the effects of natural and synthetic cannabinoids, including the components of the endocannabinoid system, in relation to the inflammation of the gut-lung-skin barrier epithelia. Recent advancements in the use of cannabinoids as anti-inflammatory substances in various disorders of the gut, lungs and skin are detailed. Some studies have reported mixed or controversial results, and these have also been addressed in our paper.

The Interplay between the Immune and the Endocannabinoid Systems in Cancer

The therapeutic potential of Cannabis sativa has been recognized since ancient times. Phytocannabinoids, endocannabinoids and synthetic cannabinoids activate two major G protein-coupled receptors, subtype 1 and 2 (CB1 and CB2). Cannabinoids (CBs) modulate several aspects of cancer cells, such as apoptosis, autophagy, proliferation, migration, epithelial-to-mesenchymal transition and stemness. Moreover, agonists of CB1 and CB2 receptors inhibit angiogenesis and lymphangiogenesis in vitro and in vivo. Low-grade inflammation is a hallmark of cancer in the tumor microenvironment (TME), which contains a plethora of innate and adaptive immune cells. These cells play a central role in tumor initiation and growth and the formation of metastasis. CB2 and, to a lesser extent, CB1 receptors are expressed on a variety of immune cells present in TME (e.g., T cells, macrophages, mast cells, neutrophils, NK cells, dendritic cells, monocytes, eosinophils). The activation of CB receptors modulates a variety of biological effects on cells of the adaptive and innate immune system. The expression of CB2 and CB1 on different subsets of immune cells in TME and hence in tumor development is incompletely characterized. The recent characterization of the human cannabinoid receptor CB2-G_i signaling complex will likely aid to design potent and specific CB2/CB1 ligands with therapeutic potential in cancer.

Depletion of CD56+CD3+ invariant natural killer T cells prevents allergen-induced inflammation in humanized mice

BACKGROUND

CD56-expressing natural killer (NK) cells as well as invariant NK T (iNKT) cells have been shown to either promote or inhibit allergic immune responses.

OBJECTIVE

The aim of the present study was to investigate the impact of these cells in a recently developed humanized mouse model of allergen-induced IgE-dependent gut and lung inflammation.

METHODS

Nonobese diabetic-severe combined immunodeficiency γ-chain knockout mice were injected intraperitoneally with human PBMCs or CD56-depleted (CD56^neg) PBMCs from highly sensitized donors with birch or grass pollen allergy together with the respective allergen or with NaCl as a control. Three weeks later, the mice were challenged with the allergen rectally and gut inflammation was monitored by video miniendoscopy and by histology. Furthermore, airway inflammation was measured after an additional intranasal allergen challenge.

RESULTS

Allergen-specific human IgE in mouse sera, detectable only after coinjection of the respective allergen, was reduced in mice being injected with CD56^neg PBMCs compared with in mice receiving nondepleted PBMCs. Consequently, allergen-induced IgE-dependent colitis, airway hyperreactivity, and mucus-producing goblet cells were significantly inhibited in these mice. Interestingly, reconstitution of CD56^neg PBMCs with nondepleted CD56⁺ cells and with CD56⁺CD3⁺ iNKT cells restored gut as well as lung inflammation, whereas addition of CD3-depleted CD56⁺ cells did not.

CONCLUSION

These results demonstrate that allergen-specific gut and lung inflammation in PBMC-engrafted humanized mice is promoted by CD56⁺CD3⁺ iNKT cells, which opens new possibilities of therapeutic intervention in allergic diseases.

Immunomodulation by cannabinoids: Current uses, mechanisms, and identification of data gaps to be addressed for additional therapeutic application

The endocannabinoid system plays a critical role in immunity and therefore its components, including cannabinoid receptors 1 and 2 (CB₁ and CB₂), are putative druggable targets for immune-mediated diseases. Whether modulating endogenous cannabinoid levels or interacting with CB₁ or CB₂ receptors directly, cannabinoids or cannabinoid-based therapeutics (CBTs) show promise as anti-inflammatory or immune suppressive agents. Herein we provide an overview of cannabinoid effects in animals and humans that provide support for the use of CBTs in immune-mediated disease such as multiple sclerosis (MS), inflammatory bowel disease (IBD), asthma, arthritis, diabetes, human immunodeficiency virus (HIV), and HIV-associated neurocognitive disorder (HAND). This is not an exhaustive review of cannabinoid effects on immune responses, but rather provides: (1) key studies in which initial and/or novel observations were made in animal studies; (2) critical human studies including meta-analyses and randomized clinical trials (RCTs) in which CBTs have been assessed; and (3) evidence for the role of CB₁ or CB₂ receptors in immune-mediated diseases through genetic analyses of single nucleotide polymorphisms (SNPs) in the CNR1 and CNR2 genes that encode CB₁ or CB₂ receptors, respectively. Perhaps most importantly, we provide our view of data gaps that exist, which if addressed, would allow for more rigorous evaluation of the efficacy and risk to benefit ratio of the use of cannabinoids and/or CBTs for immune-mediated diseases.

Bioactive lipids, inflammation and chronic diseases

Endogenous bioactive lipids are part of a complex network that modulates a plethora of cellular and molecular processes involved in health and disease, of which inflammation represents one of the most prominent examples. Inflammation serves as a well-conserved defence mechanism, triggered in the event of chemical, mechanical or microbial damage, that is meant to eradicate the source of damage and restore tissue function. However, excessive inflammatory signals, or impairment of pro-resolving/anti-inflammatory pathways leads to chronic inflammation, which is a hallmark of chronic pathologies. All main classes of endogenous bioactive lipids - namely eicosanoids, specialized pro-resolving lipid mediators, lysoglycerophopsholipids and endocannabinoids - have been consistently involved in the chronic inflammation that characterises pathologies such as cancer, diabetes, atherosclerosis, asthma, as well as autoimmune and neurodegenerative disorders and inflammatory bowel diseases. This review gathers the current knowledge concerning the involvement of endogenous bioactive lipids in the pathogenic processes of chronic inflammatory pathologies.

Aberrant anti-viral response of natural killer cells in severe asthma

Rhinovirus infections are the main cause of asthma exacerbations. As natural killer (NK) cells are important actors of the antiviral innate response, we aimed at evaluating the functions of NK cells from severe asthma patients in response to rhinovirus-like molecules or rhinoviruses.Peripheral blood mononuclear cells from patients with severe asthma and healthy donors were stimulated with pathogen-like molecules or with the rhinoviruses (RV)-A9 and RV-2. NK cell activation, degranulation and interferon (IFN)-γ expression were analysed.NK cells from severe asthma patients were less cytotoxic than those from healthy donors in response to toll-like receptor (TLR)3, TLR7/8 or RV-A9 but not in response to RV-2 stimulation. Furthermore, when cultured with interleukin (IL)-12+IL-15, cytokines which are produced during viral infections, NK cells from patients with severe asthma were less cytotoxic and expressed less IFN-γ than NK cells from healthy donors. NK cells from severe asthmatics exhibited an exhausted phenotype, with an increased expression of the checkpoint molecule Tim-3.Together, our findings indicate that the activation of NK cells from patients with severe asthma may be insufficient during some but not all respiratory infections. The exhausted phenotype may participate in NK cell impairment and aggravation of viral-induced asthma exacerbation in these patients.

Dysfunction of transient receptor potential ion channels as an important pathophysiological mechanism in asthma

Asthma is a chronic heterogeneous disease characterized by chronic inflammation and bronchial hyperreactivity. Neurogenic inflammation is one of the important causes of hyperreactivity. Dysfunction of transient receptor potential (TRP) ion channels underlies the development of neurogenic inflammation, bronchial hyperreactivity and respiratory symptoms of asthma such as bronchospasm and cough. TRP channels are expressed in the respiratory tract. Their activation is mediated by endogenous and exogenous factors involved in the pathogenesis of asthma. The study of functioning and regulation of TRP channels is relevant, as they could be important therapeutic targets for asthma. The aim of the review is to summarize modern ideas about the mechanisms of functioning and regulation of members of the TRP channel superfamily, the role of which in lung pathology and physiology are the best studied.

Regulation of Innate Lymphoid Cells in Acute Kidney Injury: Crosstalk between Cannabidiol and GILZ

Innate lymphoid cells (ILCs) have emerged as largely tissue-resident archetypal cells of the immune system. We tested the hypotheses that renal ischemia-reperfusion injury (IRI) is a contributing factor to polarization of ILCs and that glucocorticoid-induced leucine zipper (GILZ) and cannabidiol regulate them in this condition. Mice subjected to unilateral renal IRI were treated with the following agents before restoration of renal blood flow: cannabidiol, DMSO, transactivator of transcription- (TAT-) GILZ, or the TAT peptide. Thereafter, kidney cells were prepared for flow cytometry analyses. Sham kidneys treated with either cannabidiol or TAT-GILZ displayed similar frequencies of each subset of ILCs compared to DMSO or TAT, respectively. Renal IRI increased ILC1s and ILC3s but reduced ILC2s compared to the sham group. Cannabidiol or TAT-GILZ treatment of IRI kidneys reversed this pattern as evidenced by reduced ILC1s and ILC3s but increased ILC2s compared to their DMSO- or TAT-treated counterparts. While TAT-GILZ treatment did not significantly affect cells positive for cannabinoid receptors subtype 2 (CB2+), cannabidiol treatment increased frequency of both CB2+ and GILZ-positive (GILZ+) cells of IRI kidneys. Subsequent studies showed that IRI reduced GILZ+ subsets of ILCs, an effect less marked for ILC2s. Treatment with cannabidiol increased frequencies of each subset of GILZ+ ILCs, but the effect was more marked for ILC2s. Indeed, cannabidiol treatment increased CB2+ GILZ+ ILC2s. Collectively, the results indicate that both cannabidiol and GILZ regulate ILC frequency and phenotype, in acute kidney injury, and that the effects of cannabidiol likely relate to modulation of endogenous GILZ.

Peroxisome Proliferator-Activated Receptors as a Therapeutic Target in Asthma

The complexity of the pathogenetic mechanisms of the development of chronic inflammation in asthma determines its heterogeneity and insufficient treatment effectiveness. Nuclear transcription factors, which include peroxisome proliferator-activated receptors, that is, PPARs, play an important role in the regulation of initiation and resolution of the inflammatory process. The ability of PPARs to modulate not only lipid homeostasis but also the activity of the inflammatory response makes them an important pathogenetic target in asthma therapy. At present, special attention is focused on natural (polyunsaturated fatty acids (PUFAs), endocannabinoids, and eicosanoids) and synthetic (fibrates, thiazolidinediones) PPAR ligands and the study of signaling mechanisms involved in the implementation of their anti-inflammatory effects in asthma. This review summarizes current views on the structure and function of PPARs, as well as their participation in the pathogenesis of chronic inflammation in asthma. The potential use of PPAR ligands as therapeutic agents for treating asthma is under discussion.

Endocannabinoid System in the Airways

Cannabinoids and the mammalian endocannabinoid system is an important research area of interest and attracted many researchers because of their widespread biological effects. The significant immune-modulatory role of cannabinoids has suggested their therapeutic use in several inflammatory conditions. Airways are prone to environmental irritants and stimulants, and increased inflammation is an important process in most of the respiratory diseases. Therefore, the main strategies for treating airway diseases are suppression of inflammation and producing bronchodilation. The ability of cannabinoids to induce bronchodilation and modify inflammation indicates their importance for airway physiology and pathologies. In this review, the contribution of cannabinoids and the endocannabinoid system in the airways are discussed, and the existing data for their therapeutic use in airway diseases are presented.

Introducing nitrogen atoms to amidoalkylindoles: potent and selective cannabinoid type 2 receptor agonists with improved aqueous solubility

Previously we identified a series of amidoalkylindoles as potent and selective CB2 partial agonists. In the present study, we report our continuous effort to improve the aqueous solubility by introducing N atoms to the amidoalkylindole framework. Synthesis, characterization, and pharmacology evaluations were described. Bioisosteric replacements of the indole nucleus with an indazole, azaindole and benzimidazole were explored. Benzimidazole 43 (EC50,CB1 = NA, EC50,CB2 = 0.067 μM) and azaindole 24 (EC50,CB1 = NA, EC50,CB2 = 0.048 μM) were found to be potent and selective CB2 receptor partial agonists, both with improved aqueous solubility.

[Expression and clinical significance of runt-related transcription factor 3 in children with bronchiolitis]

OBJECTIVE

To study the mRNA level of runt-related transcription factor 3 (RUNX3) in children with bronchiolitis and its clinical significance in bronchiolitis.

METHODS

A total of 54 young children with bronchiolitis were enrolled as the bronchiolitis group, among whom 28 with atopic constitution were enrolled in the atopic bronchiolitis group and 26 with non-atopic constitution were enrolled in the non-atopic bronchiolitis group. A total of 48 healthy young children were enrolled as the healthy control group, among whom 24 with atopic constitution were enrolled in the atopic healthy control group and 24 with non-atopic constitution were enrolled in the non-atopic healthy control group. Quantitative real-time PCR was used to measure the mRNA level of RUNX3 in peripheral blood mononuclear cells. ELISA was used to measure the serum levels of interleukin-4 (IL-4) and interferon gamma (IFN-γ).

RESULTS

The bronchiolitis group had a significantly lower mRNA level of RUNX3 than the healthy control group, and the atopic bronchiolitis group had a significantly lower mRNA level of RUNX3 than the non-atopic bronchiolitis, atopic healthy control, and non-atopic healthy control groups (P<0.05). The bronchiolitis group had a significantly higher serum level of IL-4 than the healthy control group, and the atopic bronchiolitis group had a significantly higher serum level of IL-4 than the non-atopic healthy control group (P<0.05). The bronchiolitis group had a significantly lower serum level of IFN-γ than the healthy control group, and the atopic bronchiolitis group had a significantly lower serum level of IFN-γ than the non-atopic bronchiolitis, atopic healthy control, and non-atopic healthy control groups (P<0.05). The correlation analysis showed that the mRNA level of RUNX3 was negatively correlated with the serum level of IL-4 and was positively correlated with the serum level of IFN-γ (P<0.05).

CONCLUSIONS

Measurement of RUNX3 gene expression in peripheral blood mononuclear cells has a certain value in identifying children with atopic constitution at high risk of asthma among children with bronchiolitis.

[Expression and clinical significance of runt-related transcription factor 3 in children with bronchiolitis]

OBJECTIVE

To study the mRNA level of runt-related transcription factor 3 (RUNX3) in children with bronchiolitis and its clinical significance in bronchiolitis.

METHODS

A total of 54 young children with bronchiolitis were enrolled as the bronchiolitis group, among whom 28 with atopic constitution were enrolled in the atopic bronchiolitis group and 26 with non-atopic constitution were enrolled in the non-atopic bronchiolitis group. A total of 48 healthy young children were enrolled as the healthy control group, among whom 24 with atopic constitution were enrolled in the atopic healthy control group and 24 with non-atopic constitution were enrolled in the non-atopic healthy control group. Quantitative real-time PCR was used to measure the mRNA level of RUNX3 in peripheral blood mononuclear cells. ELISA was used to measure the serum levels of interleukin-4 (IL-4) and interferon gamma (IFN-γ).

RESULTS

The bronchiolitis group had a significantly lower mRNA level of RUNX3 than the healthy control group, and the atopic bronchiolitis group had a significantly lower mRNA level of RUNX3 than the non-atopic bronchiolitis, atopic healthy control, and non-atopic healthy control groups (P<0.05). The bronchiolitis group had a significantly higher serum level of IL-4 than the healthy control group, and the atopic bronchiolitis group had a significantly higher serum level of IL-4 than the non-atopic healthy control group (P<0.05). The bronchiolitis group had a significantly lower serum level of IFN-γ than the healthy control group, and the atopic bronchiolitis group had a significantly lower serum level of IFN-γ than the non-atopic bronchiolitis, atopic healthy control, and non-atopic healthy control groups (P<0.05). The correlation analysis showed that the mRNA level of RUNX3 was negatively correlated with the serum level of IL-4 and was positively correlated with the serum level of IFN-γ (P<0.05).

CONCLUSIONS

Measurement of RUNX3 gene expression in peripheral blood mononuclear cells has a certain value in identifying children with atopic constitution at high risk of asthma among children with bronchiolitis.

Complement factor C5 inhibition reduces type 2 responses without affecting group 2 innate lymphoid cells in a house dust mite induced murine asthma model

Background

Complement factor C5 can either aggravate or attenuate the T-helper type 2 (T_H2) immune response and airway hyperresponsiveness (AHR) in murine models of allergic asthma. The effect of C5 during the effector phase of allergen-induced asthma is ill-defined.

Objectives

We aimed to determine the effect of C5 blockade during the effector phase on the pulmonary T_H2 response and AHR in a house dust mite (HDM) driven murine asthma model.

Methods

BALB/c mice were sensitized and challenged repeatedly with HDM via the airways to induce allergic lung inflammation. Sensitized mice received twice weekly injections with a blocking anti-C5 or control antibody 24 h before the first challenge.

Results

HDM challenge in sensitized mice resulted in elevated C5a levels in bronchoalveolar lavage fluid. Anti-C5 administered to sensitized mice prior to the first HDM challenge prevented this rise in C5a, but did not influence the influx of eosinophils or neutrophils. While anti-C5 did not impact the recruitment of CD4 T cells upon HDM challenge, it reduced the proportion of T_H2 cells recruited to the airways, attenuated IL-4 release by regional lymph nodes restimulated with HDM ex vivo and mitigated the plasma IgE response. Anti-C5 did not affect innate lymphoid cell (ILC) proliferation or group 2 ILC (ILC2) differentiation. Anti-C5 attenuated HDM induced AHR in the absence of an effect on lung histopathology, mucus production or vascular leak.

Conclusions

Generation of C5a during the effector phase of HDM induced allergic lung inflammation contributes to T_H2 cell differentiation and AHR without impacting ILC2 cells.

Electronic supplementary material

The online version of this article (10.1186/s12931-019-1136-5) contains supplementary material, which is available to authorized users.

The Role of the Endocannabinoid Signaling System in the Pathophysiology of Asthma and Obesity

Bronchial asthma (BA) and obesity are one of the major modern problem, requiring the development of an effective therapeutic strategy. The frequent combination of these diseases in one patient indicates the general pathophysiological mechanisms and future study for targeted drug exposure are needed. The endocannabinoid system is involved in a variety of physiological and pathological processes and can be considered as a general mechanism and a potential therapeutic target in asthma and obesity, the receptors of the system are expressed in many central and peripheral tissues. This signal system modulates the functions of the autonomic nervous system, immune system and microcirculation, plays an important role in the regulation of energy balance, metabolism of carbohydrates and lipids. The main research aimed at studying the functioning of this system was focused on neurology and psychiatry, while numerous scientific data demonstrate the importance of the participation of this system in the pathogenesis of other diseases. In particular, this system is involved in the mechanisms of obesity. The role of the endocannabinoid system in the pathogenesis of asthma is actively studied. The wide prevalence of the endocannabinoid signaling system and its regulatory role in the body opens up prospects for therapeutic effects in the treatment of asthma and obesity, as well as the possible phenotype of asthma, combined with obesity. The review is devoted to modern ideas about endocannabinoids, their receptors, mechanisms of action and their role in the pathophysiology of asthma and obesity. The therapeutic prospects and difficulties associated with the use of endocannabinoids and phytocannabinoids in medicine are discussed.

Precision medicine and phenotypes, endotypes, genotypes, regiotypes, and theratypes of allergic diseases

A rapidly developing paradigm for modern health care is a proactive and individualized response to patients' symptoms, combining precision diagnosis and personalized treatment. Precision medicine is becoming an overarching medical discipline that will require a better understanding of biomarkers, phenotypes, endotypes, genotypes, regiotypes, and theratypes of diseases. The 100-year-old personalized allergen-specific management of allergic diseases has particularly contributed to early awareness in precision medicine. Polyomics, big data, and systems biology have demonstrated a profound complexity and dynamic variability in allergic disease between individuals, as well as between regions. Escalating health care costs together with questionable efficacy of the current management of allergic diseases facilitated the emergence of the endotype-driven approach. We describe here a precision medicine approach that stratifies patients based on disease mechanisms to optimize management of allergic diseases.

Role of NKp46+ natural killer cells in house dust mite-driven asthma

House dust mite (HDM)‐allergic asthma is driven by T helper 2 (Th2) lymphocytes, but also innate immune cells control key aspects of the disease. The precise function of innate natural killer (NK) cells during the initiation and propagation of asthma has been very confusing, in part because different, not entirely specific, strategies were used to target these cells. We show that HDM inhalation rapidly led to the accumulation of NK cells in the lung‐draining lymph nodes and of activated CD69⁺ NK cells in the bronchoalveolar lumen. However, genetically engineered Ncr1‐DTA or Ncr1‐DTR mice that constitutively or temporarily lack NK cells, still developed all key features of acute or chronic HDM‐driven asthma, such as bronchial hyperreactivity, Th2 cytokine production, eosinophilia, mucus overproduction, and Th2‐dependent immunoglobulin serum titers. The same results were obtained by administration of conventional NK1.1 or asialo‐GM1 NK cell‐depleting antibodies, antibody‐mediated blocking of the NKG2D receptor, or genetic NKG2D deficiency. Thus, although NK cells accumulate in allergen‐challenged lungs, our findings comprehensively demonstrate that these cells are not required for HDM‐driven asthma in the mouse.

Development of selective, fluorescent cannabinoid type 2 receptor ligands based on a 1,8-naphthyridin-2-(1H)-one-3-carboxamide scaffold

Cannabinoid type 2 (CB2) receptor has been implicated in several diseases and conditions, however no CB2 receptor selective drugs have made it to market. The aim of this study was to develop fluorescent ligands as CB2 receptor tools, to enable an increased understanding of CB2 receptor expression and signalling and thereby accelerate drug discovery. Fluorescent ligands have been successfully developed for other receptors, however none with adequate subtype selectivity or imaging properties have been reported for CB2 receptor. A series of 1,8-naphthyridin-2-(1H)-one-3-carboxamides with linkers and fluorophores appended in the N1 and C3-positions were developed. Molecular modelling indicated the C3 cis-cyclohexanol-linked compounds directed the linker out of the CB2 receptor between transmembrane helices 1 and 7. Herein we report fluorescent ligand 32 (hCB2 pK i = 6.33 ± 0.02) as one of the highest affinity, selective CB2 receptor fluorescent ligands reported. Despite 32 displaying poor specific labelling of CB2 receptor, the naphthyridine scaffold with this linker remains highly promising for future development of CB2 receptor tools.

The Cell Research Trends of Asthma: A Stem Frequency Analysis of the Literature

Objective

This study summarized asthma literature indexed in the Medical Literature Analysis and Retrieval System Online (MEDLINE) and explored the history and present trends of asthma cell research by stem frequency ranking to forecast the prospect of future work.

Methods

Literature was obtained from MEDLINE for the past 30 years and divided into three groups by decade as the retrieval time. The frequency of stemmed words in each group was calculated using Python with Apache Spark and the Natural Language Tool Kit for ranking. The unique stems or shared stems of 3 decades were summarized.

Results

A total of 1331, 4393, and 7215 records were retrieved from 3 decades chronologically, and the stem ranking of the top 50 were listed by frequency. The number of stems shared with 3 decades was 26 and with the first and last 2 decades was 5 and 13.

Conclusions

The number of cell research studies of asthma has increased rapidly, and scholars have paid more attentions on experimental research, especially on mechanistic research. Eosinophils, mast cells, and T cells are the hot spots of immunocyte research, while epithelia and smooth muscle cells are the hot spots of structural cell research. The research trend is closely linked with the development of experimental technology, including animal models. Early studies featured basic research, but immunity research has dominated in recent decades. The distinct definition of asthma phenotypes associated with genetic characteristics, immunity research, and the introduction of new cells will be the hot spots in future work.

The Imbalance of FOXP3/GATA3 in Regulatory T Cells from the Peripheral Blood of Asthmatic Patients

Background

Treg cells play an important role in the pathogenic progress of asthma.

Objective

To address the alterations of Treg cells in asthma.

Methods

Proliferation-and function-associated markers of Treg cells along with the percentage of Treg cells producing some cytokine from asthmatics and healthy subjects were analyzed by flow cytometry. Besides, the expressions of USP21 and PIM2 in Treg cells were measured by cell immunochemistry after Treg cells were sorted.

Results

Treg cells from asthmatic patients showed lower proliferation activity and were more likely to be apoptotic. These cells expressed lower levels of GITR, CTLA-4, Nrp-1, and IL-10 compared to those from the healthy control. Th2-like Treg cells increased in asthmatic patients, while the percentage of IFN-r⁺ Treg cells was similar between two groups. Moreover, the percentage of IL-4⁺ Treg cells is related to the asthma control. Treg cells from asthmatic patients expressed more FOXP3 as well as GATA3; the expression level of GATA3 negatively correlated with FEV1%pred. Increased expressions of USP21 and PIM2 in Treg cells from asthmatic patients were found.

Conclusion

Treg cells decreased in asthmatic patients, with an impaired immunosupression function and a Th2-like phenotype, which may be due to overexpression of GATA3 and FOXP3, regulated by USP21 and PIM2, respectively.

Role of Natural Killer Cells in Airway Inflammation

Natural killer (NK) cells have an immune regulatory function as well as cytotoxicity against tumor or infected cells. In the airway, although NK cells constitute a small proportion of the resident lymphocytes, they play an important role in the pathogenesis of chronic inflammatory airway diseases by modulating immune responses. NK cells can promote allergic airway inflammation by increasing the production of type 2 cytokines and inducing eosinophil migration. The increased activity of NK cells can develop or aggravate the destruction of lung parenchymal cells. On the other hand, decreased apoptotic activity of NK cells in eosinophils can serve as an aggravating factor for allergic airway inflammation. The increase in interferon-γ-producing NK cells and the inhibition of type 2 immune response by NK cells can alleviate allergic airway inflammation. This review aims to define the roles of NK cells in chronic inflammatory diseases of lower and upper airways.

Prenatal tobacco smoke exposure predisposes offspring mice to exacerbated allergic airway inflammation associated with altered innate effector function

Background

Epidemiological studies suggest that prenatal and early life environmental exposures have adverse effects on pulmonary function and are important contributors in the development of childhood asthma and allergic disease. The mechanism by which environmental tobacco smoke (ETS) exposure in utero promotes the development of allergic asthma remains unclear. In this study, we investigated the immunological consequences of prenatal exposure to ETS in order to understand events responsible for the development or exacerbation of allergic asthma.

Methods

Pregnant C57BL/6 mice were exposed to either ETS or filtered air throughout gestation and the effect on pulmonary inflammation in the offspring were examined and compared. Specifically, the effects on eosinophilic inflammation, airway hyperreactivity, goblet cell hyperplasia, properties of pulmonary natural killer (NK) cells and type 2 cytokines elicited in response to inhaled house dust mite (HDM) allergen were investigated in the progeny.

Results

Exposure to ETS prenatally significantly exacerbated HDM-induced airway eosinophilic inflammation, hyperreactivity, mucus secretion, cysteinyl leukotriene biosynthesis and type 2 cytokine production in the offspring. Consistently, lung mononuclear cells from ETS-exposed offspring secreted higher levels of IL-13 when stimulated in vitro with anti-αβ TCR antibody or HDM allergen. Moreover, offspring from ETS-exposed dams exhibited a higher frequency of CD11b⁺ dendritic cells and CD3⁺CD4⁺ T lymphocytes in the lungs following allergen inhalation compared to air-exposed mice. Unexpectedly, the exacerbated allergic inflammation in the ETS-exposed offspring was associated with a reduction in CD3⁻CD19⁻NK1.1⁺CD94⁺ NK cell numbers and their IFN-γ production, highlighting a role for altered innate immunity in the enhanced allergic response.

Conclusion

Our results reveal that prenatal exposure to ETS predisposes offspring to an exacerbated allergic airway inflammation that is associated with a reduction in pulmonary NK cell function, suggesting that NK cells play a key role in controlling asthma severity.

Outstanding animal studies in allergy I. From asthma to food allergy and anaphylaxis

PURPOSE OF REVIEW

Animal models published within the past 18 months on asthma, food allergy and anaphylaxis, all conditions of rising public health concern, were reviewed.

RECENT FINDINGS

While domestic animals spontaneously develop asthma, food allergy and anaphylaxis, in animal models, divergent sensitization and challenge routes, dosages, intervals and antigens are used to induce asthmatic, food allergic or anaphylactic phenotypes. This must be considered in the interpretation of results. Instead of model antigens, gradually relevant allergens such as house dust mite in asthma, and food allergens like peanut, apple and peach in food allergy research were used. Novel engineered mouse models such as a mouse with a T-cell receptor for house dust mite allergen Der p 1, or with transgenic human hFcγR genes, facilitated the investigation of single molecules of interest. Whole-body plethysmography has become a state-of-the-art in-vivo readout in asthma research. In food allergy and anaphylaxis research, novel techniques were developed allowing real-time monitoring of in-vivo effects following allergen challenge. Networks to share tissues were established as an effort to reduce animal experiments in allergy which cannot be replaced by in-vitro measures.

SUMMARY

Natural and artificial animal models were used to explore the pathophysiology of asthma, food allergy and anaphylaxis and to improve prophylactic and therapeutic measures. Especially the novel mouse models mimicking molecular aspects of the complex immune network in asthma, food allergy and anaphylaxis will facilitate proof-of-concept studies under controlled conditions.