Substance P antagonist improves both obesity and asthma in a mouse model

The mucosal concept in chronic rhinosinusitis: Focus on the epithelial barrier

Chronic rhinosinusitis (CRS) is a common chronic nasal cavity and sinus disease affecting a growing number of individuals worldwide. Recent advances have shifted our understanding of CRS pathophysiology from a physical obstruction model of ventilation and drainage to a mucosal concept that recognizes the complexities of mucosal immunologic variations and cellular aberrations. A growing number of studies have demonstrated the alteration of the epithelial barrier during inflammatory states. Therefore, the current review has focused on the crucial role of epithelial cells within this mucosal framework in CRS, detailing the perturbed epithelial homeostasis, impaired epithelial cell barrier, dysregulated epithelial cell repair processes, and enhanced interactions between epithelial cells and immune cells. Notably, the utilization of novel technologies, such as single-cell transcriptomics, has revealed the novel functions of epithelial barriers, such as inflammatory memory and neuroendocrine functions. Therefore, this review also emphasizes the importance of epithelial inflammatory memory and the necessity of further investigations into neuroendocrine epithelial cells and neurogenic inflammation in CRS. We conclude by contemplating the prospective benefits of epithelial cell-oriented biological treatments, which are currently under investigation in rigorous randomized, double-blind clinical trials in patients with CRS with nasal polyps.

miR-212/132 attenuates OVA-induced airway inflammation by inhibiting mast cells activation through MRGPRX2 and ASAP1

Allergic asthma is a chronic inflammatory disease of airways involving complex mechanisms, including MAS-related GPR family member X2 (MRGPRX2) and its orthologue MRGPRB2 on mast cells (MCs). Although miRNAs have been previously shown to related to allergic asthma, the role of miR-212/132 in this process has not been studied. In this study, the predicted pairing of miRNAs and MRGPRX2 (MRGPRB2) mRNAs was carried out by online databases and the function was verify using in vivo and in vitro experiments. Database prediction showed that miR-212/132 interact with MRGPRX2 and MRGPRB2. miR-212/132 mimics alleviated MRGPRB2 mRNA expression as well as pathology changes in lungs and AHR of mice with airway inflammation in vivo. The expression level of MRGPRB2 in the mice lungs after inhaled OVA was also decreased by miR-212/132 mimics. Meanwhile, miR-212/132 inhibited MCs degranulation and cytokines release triggered by C48/80 in vitro. Further, ASAP1 (ARF GTPase-Activating Protein 1) was selected from the junction related pathways using RNAseq and KEGG enrichment. ASAP1 mRNA level was upregulated in airway inflammation and MCs activation and decreased by miR-212/132 mimics. miR-212/132 attenuated OVA-induced airway inflammation by inhibiting MCs activation through MRGPRX2 and ASAP1.

Is Wheat Glutenin Extract Intrinsically Allergenic? Evaluation Using a Novel Adjuvant-Free Mouse Model of Systemic Anaphylaxis

Wheat is a prominent allergenic food that can trigger life-threatening anaphylaxis. Presently, it remains unclear whether wheat glutenin (WG) extract possesses inherent sensitization potential independently, without the use of adjuvants, and whether it can sensitize mice to the extent of inducing life-threatening systemic anaphylaxis. In this study, we tested the hypothesis that repeated skin exposures to WG extract without adjuvant will sensitize mice with the resultant anaphylactic reaction upon systemic WG challenge. Balb/c mice were bred and maintained on a strict plant protein-free diet and were repeatedly exposed to a WG extract or vehicle once a week for 9 weeks. WG-specific (s)IgE and total (t)IgE levels were quantified. Mice were challenged with WG extract to induce anaphylactic reactions as measured by hypothermic shock response (HSR) and mucosal mast cell degranulation response (MMCR). We also conducted proteomic analysis of 120 spleen immune markers. These skin-sensitized mice exhibited exposure-dependent IgE responses and near-fatal anaphylaxis upon challenge. Proteomic analysis identified seven dramatically elevated immune biomarkers in anaphylactic mice. These data reveal that WG is intrinsically allergenic, and that chronic skin exposure to WG extract can prime the mice for potentially fatal anaphylaxis.

Dipeptidyl Peptidase 4 (DPP4) as A Novel Adipokine: Role in Metabolism and Fat Homeostasis

Dipeptidyl peptidase 4 (DPP4) is a molecule implicated in the regulation of metabolic homeostasis and inflammatory processes, and it exerts its main action through its enzymatic activity. DPP4 represents the enzyme most involved in the catabolism of incretin hormones; thus, its activity impacts appetite, energy balance, and the fine regulation of glucose homeostasis. Indeed, DPP4 inhibitors represent a class of antidiabetic agents widely used for the treatment of Type 2 diabetes mellitus (T2DM). DPP4 also acts as an adipokine and is mainly secreted by the adipose tissue, mostly from mature adipocytes of the visceral compartment, where it exerts autocrine and paracrine activities. DPP4 can disrupt insulin signaling within the adipocyte and in other target cells and tissues, where it also favors the development of a proinflammatory environment. This is likely at the basis of the presence of elevated circulating DPP4 levels in several metabolic diseases. In this review, we summarize the most recent evidence of the role of the DPP4 as an adipokine-regulating glucose/insulin metabolism and fat homeostasis, with a particular focus on clinical outcomes associated with its increased secretion in the presence of adipose tissue accumulation and dysfunction.

Insects as a New Complex Model in Hormonal Basis of Obesity

Nowadays, one of the biggest problems in healthcare is an obesity epidemic. Consumption of cheap and low-quality energy-rich diets, low physical activity, and sedentary work favor an increase in the number of obesity cases within many populations/nations. This is a burden on society, public health, and the economy with many deleterious consequences. Thus, studies concerning this disorder are extremely needed, including searching for new, effective, and fitting models. Obesity may be related, among other factors, to disrupting adipocytes activity, disturbance of metabolic homeostasis, dysregulation of hormonal balance, cardiovascular problems, or disorders in nutrition which may lead to death. Because of the high complexity of obesity, it is not easy to find an ideal model for its studies which will be suitable for genetic and physiological analysis including specification of different compounds’ (hormones, neuropeptides) functions, as well as for signaling pathways analysis. In recent times, in search of new models for human diseases there has been more and more attention paid to insects, especially in neuro-endocrine regulation. It seems that this group of animals might also be a new model for human obesity. There are many arguments that insects are a good, multidirectional, and complex model for this disease. For example, insect models can have similar conservative signaling pathways (e.g., JAK-STAT signaling pathway), the presence of similar hormonal axis (e.g., brain–gut axis), or occurrence of structural and functional homologues between neuropeptides (e.g., neuropeptide F and human neuropeptide Y, insulin-like peptides, and human insulin) compared to humans. Here we give a hint to use insects as a model for obesity that can be used in multiple ways: as a source of genetic and peptidomic data about etiology and development correlated with obesity occurrence as well as a model for novel hormonal-based drug activity and their impact on mechanism of disease occurrence.

Changes in ghrelin, substance P and vasoactive intestinal peptide levels in the gastroduodenal mucosa of patients with morbid obesity

AIMS

The aim of the study was to assess changes in levels of substance P (SP), vasoactive intestinal peptide (VIP) and ghrelin in the gastroduodenal mucosa of obese individuals, which has not been studied before.

METHODS

Forty-six patients with a body mass index (BMI) of >40 kg/m² and 20 patients with a BMI of 18-25 kg/m² were included in the study. VIP and SP levels in the fundus, antrum and duodenal mucosa were measured in freshly frozen tissues using enzyme-linked immunosorbent assay (ELISA). Fasting levels of ghrelin in blood were also measured with ELISA. Tissue levels of ghrelin were assessed by immunohistochemical staining, and immunoreactivity scores were used for ghrelin evaluation in tissues.

RESULTS

Antrum SP levels were higher in the obese group than in the control group. A significant number of obese patients had low VIP levels in the fundus and antrum. Intense ghrelin staining was observed in a limited number of cells in the mucosal area of the gastric fundus that was similar in the control and patient groups. In the antrum and duodenum, ghrelin staining was low in all the samples examined.

CONCLUSION

Here, we found that SP levels are increased, while VIP levels are decreased in the antrum of morbidly obese individuals. Previous studies show that SP increases gastroduodenal motility, that VIP slows it down, and that the gastric emptying rate is higher in obese individuals, preventing negative feedback mechanisms upon food intake. Therefore, increases in SP and decreases in VIP levels in the antrum may contribute to obesity by accelerating gastric emptying.

Sensory modulation of airways immunity

The airways are constantly exposed to a multitude of inhaled particles and, as such, require a finely tuned discrimination between harmful or potentially threatening stimuli, and discrete responses to maintain homeostasis. Both the immune and nervous systems have the ability to sense environmental (and internal) signals, to integrate the obtained information and to initiate a protective reaction. Lung immunity and innervation are known to be individually involved in these processes, but it is becoming clear that they can also influence one another via a multitude of complex mechanisms. Here, we specifically describe how sensory innervation affects airways immunity with a focus on pathological conditions such as asthma or infections, describing cellular and molecular mechanisms, and highlighting potentially novel therapeutic targets.

Substance P-induced lung inflammation in mice is mast cell dependent

BACKGROUND

Allergic asthma is a common inflammatory lung disease and a major health problem worldwide. Mast cells (MCs) play a key role in the early-stage pathophysiology of allergic asthma. Substance P (SP) functions in neurogenic inflammation by activating MCs, and therefore, it may to participate in the occurrence and development of asthma.

OBJECTIVE

We examined the relationship between SP and lung inflammation, and also whether SP can directly trigger asthma.

METHODS

We measured the number of peripheral blood eosinophils, neutrophils and basophils and evaluated the levels of IgE and SP in blood samples of 86 individuals with allergic asthma. Serum IgE and SP levels were also determined in 29 healthy individuals. C57BL/6 mice were subjected to different doses of SP, and bronchoalveolar lavage fluid (BALF) was collected to count the inflammatory cells. Lung tissues were analysed using histopathological methods to evaluate lung peribronchial inflammation, fibrosis and glycogen deposition. Levels of IgE, interleukin (IL)-1, IL-2, IL-4, IL-5, IL-13, IL-17 and IFN-γ were determined in mouse serum.

RESULTS

Substance P levels were increased in the serum samples of patients with asthma. SP induced mouse lung peribronchial inflammation, fibrosis and glycogen deposition, with high levels of Th2-related cytokines such as IL-4, IL-5 and IL-13 observed in the BALF. Furthermore, low level of total IgE was noted in the serum, and SP had little effect on MC-deficient kit^W-sh/W-sh mice.

CONCLUSIONS & CLINICAL RELEVANCE

Substance P levels increased significantly in serum of asthmatic patients and independently associated with the risk of asthma. Furthermore, SP induced Th2 lung inflammation in mice, which was dependent on MCs.

The role of regulatory neuropeptides and neurotrophic factors in asthma pathophysiology

In the last decade, the attention of scientists in the field of biomedicine is focused on studying the relationship between the immunological and neurogenic components of the inflammatory response and their contribution to the pathophysiology of allergic inflammation in asthma. The review is devoted to detailing the mechanism of neurogenic inflammation involving regulatory neuropeptides (substance P, vasoactive intestinal peptide, calcitonin gene-related peptide) in the pathogenesis of bronchial hyperreactivity in asthma. The role of neurotrophic growth factors (nerve growth factor, brain-derived neurotrophic factor) in the regulation of remodeling of bronchi in asthma has been analyzed. The study of neuroimmune mechanisms in the pathophysiology of asthma will it possible to find new therapeutic targets in this research area.

CD26 and Asthma: a Comprehensive Review

Asthma is a heterogeneous and chronic inflammatory family of disorders of the airways with increasing prevalence that results in recurrent and reversible bronchial obstruction and expiratory airflow limitation. These diseases arise from the interaction between environmental and genetic factors, which collaborate to cause increased susceptibility and severity. Many asthma susceptibility genes are linked to the immune system or encode enzymes like metalloproteases (e.g., ADAM-33) or serine proteases. The S9 family of serine proteases (prolyl oligopeptidases) is capable to process peptide bonds adjacent to proline, a kind of cleavage-resistant peptide bonds present in many growth factors, chemokines or cytokines that are important for asthma. Curiously, two serine proteases within the S9 family encoded by genes located on chromosome 2 appear to have a role in asthma: CD26/dipeptidyl peptidase 4 (DPP4) and DPP10. The aim of this review is to summarize the current knowledge about CD26 and to provide a structured overview of the numerous functions and implications that this versatile enzyme could have in this disease, especially after the detection of some secondary effects (e.g., viral nasopharyngitis) in type II diabetes mellitus patients (a subset with a certain risk of developing obesity-related asthma) upon CD26 inhibitory therapy.

Transient Receptor Potential Ankyrin 1 Enhances Ovalbumin-Induced Acute Allergic Inflammation in Murine Models

BACKGROUND

Transient receptor potential ankyrin 1 (TRPA1) is an ion channel known to mediate nociception and neurogenic inflammation, and to be activated by reactive oxygen and nitrogen species (ROS and RNS) produced at the sites of inflammation. Because neurogenic inflammation as well as the release of ROS and RNS are typical features of early stages of allergic responses, we hypothesized that TRPA1 may be involved in triggering and/or amplifying allergic inflammation.

OBJECTIVE

This study aims at exploring the role of TRPA1 ion channel in acute ovalbumin-induced allergic inflammation in applicable murine models.

METHODS

The effects of pharmacological blockade and genetic deletion of TRPA1 in ovalbumin-induced allergic conjunctivitis and acute paw inflammation were studied in mice sensitized to ovalbumin.

RESULTS

Ovalbumin-induced allergic conjunctivitis was milder in TRPA1-deficient mice and alleviated in wild-type mice treated with the TRPA1 antagonist TCS 5861528. Subcutaneous challenge with ovalbumin caused a significant paw edema and interleukin (IL)-4 production in sensitized mice; these responses were attenuated in animals treated with the TRPA1 antagonist and in TRPA1-deficient mice. Interestingly, blockade of the major secondary effector of TRPA1, substance P, also resulted in attenuated ovalbumin-induced paw edema and IL-4 production. However, the splenocytes' responses to ovalbumin were similar in cells from wild-type and TRPA1-deficient mice sensitized to ovalbumin.

CONCLUSION

These results introduce a novel concept that TRPA1 mediates early events in allergic inflammation, but does not seem to affect allergic sensitization, and could therefore be a novel drug target to treat conditions associated with allergic inflammation.

Females have stronger neurogenic response than males after non-specific nasal challenge in patients with seasonal allergic rhinitis

Epidemiological studies show female predominance in the prevalence of non- allergic rhinitis (NAR) and local allergic rhinitis (LAR). Experimental studies show female patients with allergic rhinitis (AR) demonstrate higher levels of sensitivity to irritants and airway hyperresponsiveness than males. Bronchial asthma shows female predominance in post-puberty patients, and gender interaction with severe asthma endotypes. Fibromyalgia, chronic fatigue syndrome, migraine and chronic cough, syndromes, which are commonly related to neurokinin substance P (SP) in the literature, also show strong female predominance. Studies have demonstrated that sex hormones, primarily oestrogens, affect mast cell activation. Mast cell proteases can amplify neurogenic inflammatory responses including the release of SP. Based on human epidemiological data and animal experimental data we hypothesized that female patients have different interaction between mast cell activation and neurogenic inflammation, i.e. substance P release, resulting in a different nasal symptom profile. To test the hypothesis we performed allergen and non-specific nasal challenges in patients with seasonal allergic rhinitis (SAR) out of season and looked for gender differences in subjective and objective responses. The interaction between subjective and objective reactivity was evaluated through the comparison of subjective symptom scores, concentrations of neurokinin substance P (SP) and cellular markers in nasal lavages after low doses of nasal allergen challenges. Female allergic subjects tended to have higher substance P (SP) concentrations both before and after non-specific challenges. The difference between post-allergen and post - hypertonic saline (HTS) challenge was highly significant in female patients (p = 0.001), while insignificant in male subjects (p = 0.14). Female patients had significantly stronger burning sensation after HTS challenge than male. These data indicate difference in the interaction between inflammatory cells and the neurogenic response, which is gender- related, and which may affect symptom profiles after challenges. Different regulation of neurogenic inflammation in females may have impact on symptoms and endotyping in respiratory disorders, not only in allergic rhinitis, but also asthma, chronic rhinosinusitis and irritant -induced cough.

Antiinflammatory effects of aprepitant coadministration with cART regimen containing ritonavir in HIV-infected adults

BACKGROUND

HIV-infected individuals, even well controlled with combined antiretroviral therapy (cART), have systemic inflammation and comorbidities. Substance P (SP) is an undecapeptide, which mediates neurotransmission and inflammation through its cognate neurokinin 1 receptor (NK1R). Plasma SP levels are elevated in HIV-infected individuals. The FDA-approved antiemetic aprepitant, an NK1R antagonist, has anti-HIV effects and antiinflammatory actions. We evaluated the safety, pharmacokinetics, and antiinflammatory properties of aprepitant in HIV-positive individuals receiving cART.

METHODS

We conducted a phase 1B study of 12 HIV-positive individuals on a ritonavir-containing regimen (HIV viral load less than 40 copies/ml and CD4 > 400 cells/μl). Participants received open-label aprepitant 375 mg per day for 28 days and were followed for an additional 30 days. Changes in plasma levels of proinflammatory markers were assessed using flow cytometry, ELISA, luminex, and SOMAscan assays.

RESULTS

The mean peak aprepitant plasma concentration was 30.7 ± 15.3 μg/ml at day 14 and 23.3 ± 12.3 μg/ml at day 28. Aprepitant treatment resulted in decreased plasma SP levels and affected 176 plasma proteins (56 after FDR) and several metabolic pathways, including inflammation and lipid metabolism. No change in soluble CD163 was observed. Aprepitant treatment was associated with a moderate increases in total and HDL cholesterol and affected select hematologic and metabolic markers, which returned to baseline levels 30 days after aprepitant treatment was stopped. There were 12 mild and 10 moderate adverse events (AE).

CONCLUSIONS

Aprepitant is safe and well tolerated. The antiinflammatory properties of aprepitant make it a possible adjunctive therapy for comorbid conditions associated with HIV infection.

TRIAL REGISTRATION

ClinicalTrials.gov (NCT02154360).

FUNDING

This research was funded by NIH UO1 MH090325, P30 MH097488, and PO1 MH105303.

Obesity promotes prolonged ovalbumin-induced airway inflammation modulating T helper type 1 (Th1), Th2 and Th17 immune responses in BALB/c mice

Clinical and epidemiological studies indicate that obesity affects the development and phenotype of asthma by inducing inflammatory mechanisms in addition to eosinophilic inflammation. The aim of this study was to assess the effect of obesity on allergic airway inflammation and T helper type 2 (Th2) immune responses using an experimental model of asthma in BALB/c mice. Mice fed a high-fat diet (HFD) for 10 weeks were sensitized and challenged with ovalbumin (OVA), and analyses were performed at 24 and 48 h after the last OVA challenge. Obesity induced an increase of inducible nitric oxide synthase (iNOS)-expressing macrophages and neutrophils which peaked at 48 h after the last OVA challenge, and was associated with higher levels of interleukin (IL)-4, IL-9, IL-17A, leptin and interferon (IFN)-γ in the lungs. Higher goblet cell hyperplasia was associated with elevated mast cell influx into the lungs and trachea in the obese allergic mice. In contrast, early eosinophil influx and lower levels of IL-25, thymic stromal lymphopoietin (TSLP), CCL11 and OVA-specific immunoglobulin (IgE) were observed in the obese allergic mice in comparison to non-obese allergic mice. Moreover, obese mice showed higher numbers of mast cells regardless of OVA challenge. These results indicate that obesity affects allergic airway inflammation through mechanisms involving mast cell influx and the release of TSLP and IL-25, which favoured a delayed immune response with an exacerbated Th1, Th2 and Th17 profile. In this scenario, an intense mixed inflammatory granulocyte influx, classically activated macrophage accumulation and intense mucus production may contribute to a refractory therapeutic response and exacerbate asthma severity.

Neuropeptide substance P and the immune response

Substance P is a peptide mainly secreted by neurons and is involved in many biological processes, including nociception and inflammation. Animal models have provided insights into the biology of this peptide and offered compelling evidence for the importance of substance P in cell-to-cell communication by either paracrine or endocrine signaling. Substance P mediates interactions between neurons and immune cells, with nerve-derived substance P modulating immune cell proliferation rates and cytokine production. Intriguingly, some immune cells have also been found to secrete substance P, which hints at an integral role of substance P in the immune response. These communications play important functional roles in immunity including mobilization, proliferation and modulation of the activity of immune cells. This review summarizes current knowledge of substance P and its receptors, as well as its physiological and pathological roles. We focus on recent developments in the immunobiology of substance P and discuss the clinical implications of its ability to modulate the immune response.

The NK1R-/- mouse phenotype suggests that small body size, with a sex- and diet-dependent excess in body mass and fat, are physical biomarkers for a human endophenotype with vulnerability to attention deficit hyperactivity disorder

The abnormal behaviour of NK1R-/- mice (locomotor hyperactivity, inattentiveness and impulsivity in the 5-Choice Serial Reaction-Time Test) is arguably analogous to that of patients with attention deficit hyperactivity disorder (ADHD). Evidence suggests that small body size and increased body weight are risk factors for ADHD. Here, we compared the body size, body mass and body composition of male and female NK1R-/- mice and their wildtypes that had been fed either standard laboratory chow or a high-fat (45%: 'Western') diet. Male NK1R-/- mice from both cohorts were approximately 7% shorter than wildtypes. A similar trend was evident in females. Male NK1R-/- mice fed the normal diet weighed less than wildtypes but the 'body mass index' ('mBMI': weight (mg)/length (cm)(2)) of female NK1R-/- mice was higher than wildtypes. When given the high-fat diet, the mBMI of both male and female NK1R-/- mice was higher than wildtypes. There were no consistent genotype or sex differences in protein, ash or water content of mice from the two cohorts. However, the fat content of male NK1R-/- mice on the Western diet was considerably (35%) higher than wildtypes and resembled that of females from both genotypes. We conclude that a lack of functional NK1R is associated with small body size but increases vulnerability to an increase in mBMI and fat content, especially in males. This phenotype could also be evident in ADHD patients with polymorphism(s) of the TACR1 gene (the human equivalent of Nk1r).

Association between obesity and asthma - epidemiology, pathophysiology and clinical profile

Obesity is a risk factor for asthma, and obese asthmatics have lower disease control and increased symptom severity. Several putative links have been proposed, including genetics, mechanical restriction of the chest and the intake of corticosteroids. The most consistent evidence, however, comes from studies of cytokines produced by the adipose tissue called adipokines. Adipokine imbalance is associated with both proinflammatory status and asthma. Although reverse causation has been proposed, it is now acknowledged that obesity precedes asthma symptoms. Nevertheless, prenatal origins of both conditions complicate the search for causality. There is a confirmed role of neuro-immune cross-talk mediating obesity-induced asthma, with leptin playing a key role in these processes. Obesity-induced asthma is now considered a distinct asthma phenotype. In fact, it is one of the most important determinants of asthma phenotypes. Two main subphenotypes have been distinguished. The first phenotype, which affects adult women, is characterised by later onset and is more likely to be non-atopic. The childhood obesity-induced asthma phenotype is characterised by primary and predominantly atopic asthma. In obesity-induced asthma, the immune responses are shifted towards T helper (Th) 1 polarisation rather than the typical atopic Th2 immunological profile. Moreover, obese asthmatics might respond differently to environmental triggers. The high cost of treatment of obesity-related asthma, and the burden it causes for the patients and their families call for urgent intervention. Phenotype-specific approaches seem to be crucial for the success of prevention and treatment.

Obesity and asthma: current knowledge and future needs

PURPOSE OF REVIEW

Obesity has significant impact on asthma incidence and manifestations. The purpose of the review is to discuss recent observations regarding the association between obesity and asthma focusing on underlying mechanisms, clinical presentation, response to therapy and effect of weight reduction.

RECENT FINDINGS

Clinical and epidemiological studies indicate that obese patients with asthma may represent a unique phenotype, which is more difficult to control, less responsive to asthma medications and by that may have higher healthcare utilization. A number of common comorbidities have been linked to both obesity and asthma, and may, therefore, contribute to the obese-asthma phenotype. Furthermore, recently published studies indicate that even a modest weight reduction can improve clinical manifestations and outcome of asthma.

SUMMARY

Compared with normal-weight patients, obese and overweight patients with asthma have poorer asthma control and respond less to corticosteroid therapy. Future studies focusing on the mechanism underlying both obesity and asthma including the obese-asthma phenotype are required to better characterize the link between the conditions and target the management of this patient group.

Chronic neurokinin-1 receptor antagonism fails to ameliorate clinical signs, airway hyper-responsiveness or airway eosinophilia in an experimental model of feline asthma

OBJECTIVES

Feline allergic asthma is a common chronic lower airway disease characterized by clinical signs attributed to eosinophilic inflammation, airway hyper-responsiveness (AHR) and airway remodeling. Tachykinins released from sensory nerves and immune cells bind neurokinin-1 (NK-1) receptors in the lung. The resultant neurogenic airway inflammation has been implicated in asthma pathogenesis. In mouse models and spontaneous human asthma, NK receptor antagonists reduce bronchospasm and inflammation. We hypothesized that chronic administration of maropitant, an NK-1 receptor antagonist, would decrease clinical signs of asthma, AHR and eosinophilic inflammation in experimentally asthmatic cats.

METHODS

Cats (n = 6) induced to have asthma using Bermuda grass allergen (BGA) were enrolled in a randomized, prospective, placebo-controlled crossover design study. Cats received either oral maropitant (2 mg/kg) or placebo q48h for 4 weeks; following a 2 week washout, cats were crossed-over to the alternate treatment. Study endpoints included subjective clinical scoring systems after BGA challenge, ventilator-acquired pulmonary mechanics to assess AHR after bronchoprovocation with methacholine, and collection of bronchoalveolar lavage fluid to quantify airway eosinophilia. Statistical analysis was performed using a Mann-Whitney rank sum test with P <0.05 considered significant.

RESULTS

Administration of maropitant for 1 month in experimentally asthmatic cats produced no significant difference in clinical scoring scheme (P = 0.589 and P = 1.0), AHR (P = 0.818) or airway eosinophilia (P = 0.669) compared with placebo.

CONCLUSIONS AND RELEVANCE

Chronic administration of maropitant was ineffective at blunting clinical signs, AHR and airway eosinophilia in experimental feline asthma and thus cannot be recommended as a novel treatment for this disorder.

Immunological characteristics and management considerations in obese patients with asthma

Obesity is associated with severe, poorly controlled asthma that does not respond as well to therapy as asthma in leaner asthmatics. Important insights gained from animal models of obesity and asthma suggests that different forms of obesity may lead to different manifestations of airway disease: obesity is associated with both innate increased airway reactivity and altered responses to aeroallergen and pollutant challenges. In humans, at least two broad groups of obese asthmatics have been recognized: one that is likely unique to obesity and another that is likely lean allergic asthma much complicated by obesity. This article will discuss what we have learned about the immunological and pathophysiological basis of asthma in obesity from animal and human studies, and how this might guide therapy.

Gut-brain peptides in corticostriatal-limbic circuitry and alcohol use disorders

Peptides synthesized in endocrine cells in the gastrointestinal tract and neurons are traditionally considered regulators of metabolism, energy intake, and appetite. However, recent work has demonstrated that many of these peptides act on corticostriatal-limbic circuitry and, in turn, regulate addictive behaviors. Given that alcohol is a source of energy and an addictive substance, it is not surprising that increasing evidence supports a role for gut-brain peptides specifically in alcohol use disorders (AUD). In this review, we discuss the effects of several gut-brain peptides on alcohol-related behaviors and the potential mechanisms by which these gut-brain peptides may interfere with alcohol-induced changes in corticostriatal-limbic circuitry. This review provides a summary of current knowledge on gut-brain peptides focusing on five peptides: neurotensin, glucagon-like peptide 1, ghrelin, substance P, and neuropeptide Y. Our review will be helpful to develop novel therapeutic targets for AUD.

Autocrine hemokinin-1 functions as an endogenous adjuvant for IgE-mediated mast cell inflammatory responses

BACKGROUND

Efficient development of atopic diseases requires interactions between allergen and adjuvant to initiate and amplify the underlying inflammatory responses. Substance P (SP) and hemokinin-1 (HK-1) are neuropeptides that signal through the neurokinin-1 receptor (NK1R) to promote inflammation. Mast cells initiate the symptoms and tissue effects of atopic disorders, secreting TNF and IL-6 after FcεRI cross-linking by antigen-IgE complexes (FcεRI-activated mast cells [FcεRI-MCs]). Additionally, MCs express the NK1R, suggesting an adjuvant role for NK1R agonists in FcεRI-MC-mediated pathologies; however, in-depth research addressing this relevant aspect of MC biology is lacking.

OBJECTIVE

We sought to investigate the effect of NK1R signaling and the individual roles of SP and HK-1 as potential adjuvants for FcεRI-MC-mediated allergic disorders.

METHODS

Bone marrow-derived mast cells (BMMCs) from C57BL/6 wild-type (WT) or NK1R(-/-) mice were used to investigate the effects of NK1R signaling on FcεRI-MCs. BMMCs generated from Tac1(-/-) mice or after culture with Tac4 small interfering RNA were used to address the adjuvancy of SP and HK-1. WT, NK1R(-/-), and c-Kit(W-sh/W-sh) mice reconstituted with WT or NK1R(-/-) BMMCs were used to evaluate NK1R signaling on FcεRI-MC-mediated passive local and systemic anaphylaxis and on airway inflammation.

RESULTS

FcεRI-activated MCs upregulated NK1R and HK-1 transcripts and protein synthesis, without modifying SP expression. In a positive signaling loop HK-1 promoted TNF and IL-6 secretion by MC degranulation and protein synthesis, the latter through the phosphoinositide 3-kinase/Akt/nuclear factor κB pathways. In vivo NK1R signaling was necessary for the development of passive local and systemic anaphylaxis and airway inflammation.

CONCLUSIONS

FcεRI stimulation of MCs promotes autocrine secretion of HK-1, which signals through NK1R to provide adjuvancy for efficient development of FcεRI-MC-mediated disorders.

Mechanisms of obesity in asthma

PURPOSE OF REVIEW

Obesity and asthma are chronic conditions affecting millions of people worldwide. The two conditions also appear to be linked with an increased risk of asthma in people who are obese. The purpose of this review is to describe mechanism(s) that may explain the association between asthma and obesity.

RECENT FINDINGS

Current evidence suggests that the association between asthma and obesity is linked by two major phenotypes and three important pathways of obesity-related asthma: one phenotype with primary (often atopic) asthma that is aggravated by obesity and a second phenotype with late-onset nonatopic asthma, which predominantly affects women and primarily seems to be associated with neutrophilic inflammation. Proposed pathways include the mechanical effects of obesity (fewer deep inspirations leading to increased airway hyperresponsiveness), an inflammatory pathway driven by obesity-related cytokines (adipokines), and finally environment and lifestyle changes that have led to an increasing prevalence of obesity over the past 50 years (including exposures in utero, physical activity, and diet) may also result in asthma in predisposed individuals. How these environmental changes influence the occurrence and expression of asthma may depend on the age of exposure and on interactions with genetic susceptibilities.

SUMMARY

Future research should be directed to shed light on the associations between obesity and asthma phenotypes, modern lifestyles and environmental exposures and genetic susceptibilities.

VIDEO ABSTRACT

http://links.lww.com/COAI/A6.

Involvement of substance P and the NK-1 receptor in human pathology

The peptide substance P (SP) shows a widespread distribution in both the central and peripheral nervous systems, but it is also present in cells not belonging to the nervous system (immune cells, liver, lung, placenta, etc.). SP is located in all body fluids, such as blood, cerebrospinal fluid, breast milk, etc. i.e. it is ubiquitous in human body. After binding to the neurokinin-1 (NK-1) receptor, SP regulates many pathophysiological functions in the central nervous system, such as emotional behavior, stress, depression, anxiety, emesis, vomiting, migraine, alcohol addiction, seizures and neurodegeneration. SP has been also implicated in pain, inflammation, hepatitis, hepatotoxicity, cholestasis, pruritus, myocarditis, bronchiolitis, abortus, bacteria and viral infection (e.g., HIV infection) and it plays an important role in cancer (e.g., tumor cell proliferation, antiapoptotic effects in tumor cells, angiogenesis, migration of tumor cells for invasion, infiltration and metastasis). This means that the SP/NK-1 receptor system is involved in the molecular bases of many human pathologies. Thus, knowledge of this system is the key for a better understanding and hence a better management of many human diseases. In this review, we update the involvement of the SP/NK-1 receptor system in the physiopathology of the above-mentioned pathologies and we suggest valuable future therapeutic interventions involving the use of NK-1 receptor antagonists, particularly in the treatment of emesis, depression, cancer, neural degeneration, inflammatory bowel disease, viral infection and pruritus, in which that system is upregulated.

Linking obesity and asthma

A growing body of literature suggests that obesity has a significant impact on asthma risk, phenotype, and prognosis. Epidemiological studies have clearly demonstrated that asthma is more likely to occur in obese patients, and health status is impaired in obese individuals with asthma, with obese asthmatics experiencing more symptoms, worse quality of life, increased healthcare use, and increased asthma severity. However, obesity has well-described effects on lung function and mechanics that can lead to symptoms of dyspnea without causing the pathophysiologic changes of asthma. Adding to the challenges of evaluating this association, some studies have failed to demonstrate a robust relationship between obesity and traditional biomarkers of airway inflammation in adult asthmatics, leading to the conclusion that obesity does not necessarily worsen airway inflammation in asthma. In this regard, emerging data suggest that nonatopic mechanisms may be relevant in obese asthmatics, and that these mechanisms may have a direct impact on the response of obese asthmatics to asthma therapies, most notably inhaled glucocorticoids. This article will review selected aspects of the contributions of obesity-related airway and systemic inflammation to asthma, with a focus on the impact of obesity as a modifier of risk, prognosis, and therapeutic response in asthma.

Neurokinin-1 receptor, a new modulator of lymphangiogenesis in obese-asthma phenotype

AIMS

Obesity and asthma are widely prevalent and associated disorders. Recent studies of our group revealed that Substance P (SP) is involved in pathophysiology of obese-asthma phenotype in mice through its selective NK1 receptor (NK1-R). Lymphangiogenesis is impaired in asthma and obesity, and SP activates contractile and inflammatory pathways in lymphatics. Our aim was to study whether NK1-R expression was involved in lymphangiogenesis on visceral (VAT) and subcutaneous (SAT) adipose tissues and in the lungs, in obese-allergen sensitized mice.

MAIN METHODS

Diet-induced obese and ovalbumin (OVA)-sensitized Balb/c mice were treated with a selective NK1-R antagonist (CJ 12,255, Pfizer Inc., USA) or placebo. Lymphatic structures (LYVE-1+) and NK1-R expression were analyzed by immunohistochemistry. A semi-quantitative score methodology was used for NK1-R expression.

KEY FINDINGS

Obesity and allergen-sensitization together increased the number of LYVE-1+ lymphatics in VAT and decreased it in SAT and lungs. NK1-R was mainly expressed on adipocyte membranes of VAT, blood vessel areas of SAT, and in lung epithelium. Obesity and allergen-sensitization combined increased the expression of NK1-R in VAT, SAT and lungs. NK1-R antagonist treatment reversed the effects observed in lymphangiogenesis in those tissues.

SIGNIFICANCE

The obese-asthma phenotype in mice is accompanied by increased expression of NK1-R on adipose tissues and lung epithelium, reflecting that SP released during inflammation may act directly on these tissues. Blocking NK1-R affects lymphangiogenesis, implying a role of SP, with opposite physiological consequences in VAT, and in SAT and lungs. Our results provide a clue for a novel SP role in the obese-asthma phenotype.

Role of transient receptor potential ion channels and evoked levels of neuropeptides in a formaldehyde-induced model of asthma in BALB/c mice

OBJECTIVE

Asthma is a complex pulmonary inflammatory disease characterized by the hyper-responsiveness, remodeling and inflammation of airways. Formaldehyde is a common indoor air pollutant that can cause asthma in people experiencing long-term exposure. The irritant effect and adjuvant effect are the two possible pathways of formaldehyde promoted asthma.

METHODOLOGY/PRINCIPAL FINDINGS

To explore the neural mechanisms and adjuvant effect of formaldehyde, 48 Balb/c mice in six experimental groups were exposed to (a) vehicle control; (b) ovalbumin; (c) formaldehyde (3.0 mg/m(3)); (d) ovalbumin+formaldehyde (3.0 mg/m(3)); (e) ovalbumin+formaldehyde (3.0 mg/m(3))+HC-030031 (transient receptor potential ankyrin 1 antagonist); (f) ovalbumin+formaldehyde (3.0 mg/m(3))+ capsazepine (transient receptor potential vanilloid 1 antagonist). Experiments were conducted after 4 weeks of combined exposure and 1-week challenge with aerosolized ovalbumin. Airway hyper-responsiveness, pulmonary tissue damage, eosinophil infiltration, and increased levels of interleukin-4, interleukin-6, interleukin-1β, immunoglobulin E, substance P and calcitonin gene-related peptide in lung tissues were found in the ovalbumin+formaldehyde (3.0 mg/m(3)) group compared with the values seen in ovalbumin -only immunized mice. Except for interleukin-1β levels, other changes in the levels of biomarker could be inhibited by HC-030031 and capsazepine.

CONCLUSIONS/SIGNIFICANCE

Formaldehyde might be a key risk factor for the rise in asthma cases. Transient receptor potential ion channels and neuropeptides have important roles in formaldehyde promoted-asthma.