Low E-prostanoid 2 receptor levels and deficient induction of the IL-1β/IL-1 type I receptor/COX-2 pathway: Vicious circle in patients with aspirin-exacerbated respiratory disease

Mast Cells in Aspirin-Exacerbated Respiratory Disease

PURPOSE OF REVIEW

Aspirin-exacerbated respiratory disease (AERD) is a syndrome of high type 2 inflammation and is known to critically involve mast cell activation. The mast cell is an important cell in the baseline inflammatory processes in the upper and lower airway by maintaining and amplifying type 2 inflammation. But it also is prominent in the hypersensitivity reaction to COX-1 inhibition which defines this condition.

RECENT FINDINGS

Recent work highlights the mast cell as a focal point in AERD pathogenesis. Using AERD as a specific model of both high type 2 asthma and chronic sinusitis, the role of mast cell activity can be better understood in other aspects of airway inflammation. Further dissecting out the mechanism of COX-1-mediated mast cell activation in AERD will be an important next phase in our understanding of NSAID-induced hypersensitivity as well as AERD pathophysiology.

Prostaglandin E2 attenuates lung fibroblast differentiation via inactivation of yes-associated protein signaling

Prostaglandin E2 (PGE2 ) has been implicated in counteracting fibroblast differentiation by TGFβ1 during pulmonary fibrosis. However, the precise mechanism is not well understood. We show here that PGE2 via EP2 R and EP4 R inhibits the expression of mechanosensory molecules Lysyl Oxidase Like 2 (LOXL2), myocardin-related transcription factor A (MRTF-A), ECM proteins, plasminogen activation inhibitor 1 (PAI-1), fibronectin (FN), α-smooth muscle actin (α-SMA), and redox sensor (nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 4 (NOX4)) required for TGFβ1-mediated fibroblast differentiation. We further demonstrate that PGE2 inhibits fibrotic signaling via Yes-associated protein (YAP) but does so independently from its actions on SMAD phosphorylation and conserved cylindromatosis (CYLD; deubiquitinase) expression. Mechanistically, PGE2 phosphorylates/inactivates YAP downstream of EP2 R/Gαs and restrains its translocation to the nucleus, thus inhibiting its interaction with TEA domain family members (TEADs) and transcription of fibrotic genes. Importantly, pharmacological or siRNA-mediated inhibition of YAP significantly downregulates TGFβ1-mediated fibrotic gene expression and myofibroblast formation. Notably, YAP expression is upregulated in the lungs of D. farinae-treated wild type (WT) mice relative to saline-treated WT mice. Our results unravel a unique role for PGE2 -YAP interactions in fibroblast differentiation, and that PGE2 /YAP inhibition can be used as a novel therapeutic target in the treatment of pathological conditions associated with myofibroblasts like asthma.

Trial of thromboxane receptor inhibition with ifetroban: TP receptors regulate eicosanoid homeostasis in aspirin-exacerbated respiratory disease

BACKGROUND

Aspirin-exacerbated respiratory disease (AERD) is the triad of asthma, nasal polyposis, and respiratory reactions to COX-1 inhibitors. Overproduction of cysteinyl leukotrienes and underproduction of prostaglandin E2 (PGE2) are hallmarks of AERD. A mouse model predicted a key role for the thromboxane-prostanoid (TP) receptor in AERD.

OBJECTIVE

Our aim was to determine whether ifetroban, a TP receptor antagonist, attenuates aspirin-induced respiratory symptoms in patients with AERD.

METHODS

A total of 35 patients with AERD completed a 4-week double-blinded, placebo-controlled trial of ifetroban and underwent an oral aspirin challenge. The primary outcome was change in the provocative dose of aspirin that caused a 2-point increase in Total Nasal Symptom Score. Changes in lung function, eicosanoid levels, and platelet and mast cell activation were assessed. Cultured human nasal fibroblasts were stimulated with or without the TP agonist U46619 and assayed for prostanoid production.

RESULTS

Ifetroban was well tolerated in AERD and did not change the mean 2-point increase in Total Nasal Symptom Score (P = .763). Participants taking ifetroban had greater aspirin-induced nasal symptoms and a greater decline in FEV1 value than did participants receiving placebo (-18.8% ± 3.6% with ifetroban vs -8.4% ± 2.1% with placebo [P = .017]). Four weeks of ifetroban significantly increased urinary leukotriene E4 levels and decreased nasal PGE2 levels compared with placebo. Peak aspirin-induced urinary thromboxane levels correlated with peak urinary leukotriene E4 and prostaglandin D2 metabolite levels in participants taking ifetroban. U46119 significantly potentiated the production of PGE2 by cultured nasal fibroblasts from subjects with AERD but not by cultured nasal fibroblasts from controls without polypoid sinusitis.

CONCLUSION

Contrary to our hypothesis, TP receptor blockade worsened aspirin-induced reactions in AERD, possibly by exacerbating dysregulation of the eicosanoid system. TP signaling on stromal cells may be critical to maintaining PGE2 production when COX-2 function is low.

Main Polymorphisms in Aspirin-Exacerbated Respiratory Disease

Aspirin exacerbated respiratory disease (AERD) is a condition caused by increased bronchoconstriction in people with asthma after taking aspirin or another NSAID. Molecular analysis of the human genome has opened up new perspectives on human polymorphisms and disease. This study was conducted to identify the genetic factors that influence this disease due to its unknown genetic factors. We evaluated research studies, letters, comments, editorials, eBooks, and reviews. PubMed/MEDLINE, Web of Sciences, Cochrane Library, and Scopus were searched for information. We used the keywords polymorphisms, aspirin-exacerbated respiratory disease, asthma, allergy as search terms. This study included 38 studies. AERD complications were associated with polymorphisms in ALOX15, EP2, ADRB2, SLC6A12, CCR3, CRTH2, CysLTs, DPCR1, DPP10, FPR2, HSP70, IL8, IL1B, IL5RA, IL-13, IL17RA, ILVBL, TBXA2R, TLR3, HLA-DRB and HLA-DQ, HLA-DR7, HLA-DP. AERD was associated with heterogeneity in gene polymorphisms, making it difficult to pinpoint specific gene changes. Therefore, diagnosing and treating AERD may be facilitated by examining common variants involving the disease.

Metabolic regulation by prostaglandin E2 impairs lung group 2 innate lymphoid cell responses

BACKGROUND

Group 2 innate lymphoid cells (ILC2s) play a critical role in asthma pathogenesis. Non-steroidal anti-inflammatory drug (NSAID)-exacerbated respiratory disease (NERD) is associated with reduced signaling via EP2, a receptor for prostaglandin E2 (PGE2 ). However, the respective roles for the PGE2 receptors EP2 and EP4 (both share same downstream signaling) in the regulation of lung ILC2 responses has yet been deciphered.

METHODS

The roles of PGE2 receptors EP2 and EP4 on ILC2-mediated lung inflammation were investigated using genetically modified mouse lines and pharmacological approaches in IL-33-induced lung allergy model. The effects of PGE2 receptors and downstream signals on ILC2 metabolic activation and effector function were examined using in vitro cell cultures.

RESULTS

Deficiency of EP2 rather than EP4 augments IL-33-induced mouse lung ILC2 responses and eosinophilic inflammation in vivo. In contrast, exogenous agonism of EP4 and EP2 or inhibition of phosphodiesterase markedly restricts IL-33-induced lung ILC2 responses. Mechanistically, PGE2 directly suppresses IL-33-dependent ILC2 activation through the EP2/EP4-cAMP pathway, which downregulates STAT5 and MYC pathway gene expression and ILC2 energy metabolism. Blocking glycolysis diminishes IL-33-dependent ILC2 responses in mice where endogenous PG synthesis or EP2 signaling is blocked but not in mice with intact PGE2 -EP2 signaling.

CONCLUSION

We have defined a mechanism for optimal suppression of mouse lung ILC2 responses by endogenous PGE2 -EP2 signaling which underpins the clinical findings of defective EP2 signaling in patients with NERD. Our findings also indicate that exogenously targeting the PGE2 -EP4-cAMP and energy metabolic pathways may provide novel opportunities for treating the ILC2-initiated lung inflammation in asthma and NERD.

Mechanisms by which dupilumab normalizes eicosanoid metabolism and restores aspirin-tolerance in AERD: A hypothesis

Aspirin-exacerbated respiratory disease (AERD) is associated with overproduction of proinflammatory cysteinyl leukotrienes (CysLTs), defective generation of anti-inflammatory prostaglandin E₂ (PGE₂), and reduced expression of the EP2 receptor for PGE₂. Reduced PGE₂ synthesis results from the downregulation of inducible COX-2. Because PGE₂ signaling via EP2 inhibits the 5-lipoxygenase/leukotriene C₄ synthase-dependent pathway, the deficient levels of both PGE₂ and EP2 likely contribute to the excessive baseline production of cysteinyl leukotrienes in patients with AERD compared with in patients with aspirin-tolerant asthma. The COX-2 pathway is regulated by an autocrine metabolic loop involving IL-1β, IL-1 receptor type I, EP2, COX-2, membrane-bound PGE₂ prostaglandin E₂ synthase-1, and PGE₂. Previous studies reported that this metabolic loop is dysregulated in patients with AERD. When the downexpressed EP2 receptor is normalized, the entire loop returns to its normal function. Cotreatment of airway cells from healthy subjects with IL-4 and IFN-γ induces alterations in the metabolic loop similar to those seen in patients with AERD. In these patients, IL-4, which is produced in excess in airways of patients with AERD, likely contributes to the alteration of normal functioning of the autocrine metabolic loop involving IL-1β, IL-1 receptor type I, EP2, COX-2, membrane-bound PGE₂ prostaglandin E₂ synthase-1, and PGE₂. We hypothesized that by blocking IL-4 action, dupilumab normalizes EP2 expression and restores the normal functioning of the COX-2 pathway autocrine metabolic loop, thereby normalizing the synthesis of PGE₂ and restoring aspirin tolerance.

Updates on immune mechanisms in aspirin-exacerbated respiratory disease

Aspirin-exacerbated respiratory disease has fascinated and frustrated specialists in allergy/immunology, pulmonology, and otorhinolaryngology for decades. It generally develops in previously healthy young adults and is unremitting and challenging to treat. The classical triad of asthma, nasal polyposis, and pathognomonic respiratory reactions to aspirin and other cyclooxygenase-1 inhibitors is accompanied by high levels of mast cell activation, cysteinyl leukotriene production, platelet activation, and severe type 2 respiratory inflammation. The "unbraking" of mast cell activation and further cysteinyl leukotriene generation induced by cyclooxygenase-1 inhibition reflect an idiosyncratic dependency on cyclooxygenase-1-derived products, likely prostaglandin E2, to maintain a tenuous homeostasis. Although cysteinyl leukotrienes are clear disease effectors, little else was known about their cellular sources and targets, and the contributions from other mediators and type 2 respiratory inflammation effector cells to disease pathophysiology were unknown until recently. The applications of targeted biological therapies, single-cell genomics, and transgenic animal approaches have substantially advanced our understanding of aspirin-exacerbated respiratory disease pathogenesis and treatment and have also revealed disease heterogeneity. This review covers novel insights into the immunopathogenesis of aspirin-exacerbated respiratory disease from each of these lines of research, including the roles of lipid mediators, effector cell populations, and inflammatory cytokines, discusses unanswered questions regarding cause and pathogenesis, and considers potential future therapeutic options.

Effect of MP-AzeFlu compared to monotherapy on COX-2, PGE2 , and EP2 gene expression in upper airway mucosa

MP-AzeFlu (intranasal fluticasone and azelastine) has been widely studied and has demonstrated efficacy in Allergic rhinitis with a superior effect compared to these drugs administered individually; however, the mechanism by which MP-AzeFlu produces this improved clinical effect has not yet been fully explained. In this study, we investigated the effect of MP-AzeFlu and fluticasone propionate (FP) on arachidonic acid metabolism as measured by changes in regulation of cyclooxygenase (COX) isoforms, prostaglandin (PG) D₂ , PGE₂ , PGE₂ receptor (EP) 2, and EP3. Expression of these key inflammation markers was assessed through an in vitro model of upper airway inflammation using fibroblasts derived from both healthy and inflamed upper airway mucosa. Both MP-AzeFlu and FP inhibited interleukin-1β-induced COX-2 messenger RNA (mRNA) and protein expression and PGE₂ secretion in vitro. MP-AzeFlu and FP both upregulated EP2 mRNA expression, though neither upregulated EP2 protein expression. This downregulation of COX-2 and PGE₂ coupled with upregulation of EP2 receptor expression reinforces the anti-inflammatory effect of MP-AzeFlu in upper airway inflammation.

The Role of Omalizumab in NSAID-Exacerbated Respiratory Disease: A Narrative Review

Nonsteroidal anti-inflammatory drug-exacerbated respiratory disease (N-ERD) is a condition characterized by the triad of chronic rhinosinusitis with nasal polyps, bronchial asthma, and hypersensitivity to nonsteroidal anti-inflammatory drugs. This article explores the current knowledge on the various pathological mechanism(s) of N-ERD-such as arachidonic acid metabolism, cysteinyl leukotrienes, prostaglandins, platelets, IgE, mast cells, eosinophils, basophils, and innate immune system-and the role of omalizumab in its management. The authors dive deep into the role of IgE in N-ERD and its potential as a therapeutic target. IgE plays a significant role in mediating allergic reactions, is intricately linked with mast cells, interacts with multiple immunopathological pathways involved in N-ERD, and tends to be elevated in patients with N-ERD. Multiple real-world studies, observational studies, and case series, as well as 2 phase III trials, have demonstrated the effectiveness of omalizumab in the management of N-ERD. For a disease with such a well-documented history, the pathophysiology of N-ERD and the most effective ways to manage it remain a mystery. With this background, the authors ask-is IgE a missing piece of the N-ERD puzzle, thus explaining the efficacy of omalizumab in the treatment of the disease?

Advances in Mast Cell Biology

Mast cells (MCs) contribute prominently to all allergic diseases, yet are still poorly understood owing to their exclusive residence in tissues. Recently, the use of RNA-sequencing, proteomics, and other technological advances have accelerated the acquisition of new knowledge. This includes an expanded definition of MC heterogeneity and developmental origins, previously unrecognized functions for MCs, discoveries of genetic causes of MC-related disorders, the introduction of new therapies for clonal MC disease, and the identification of new potential target for treatments. This issue of Advances addresses key studies from 2020 to 2021.

Hepatoprotective effect of ferulic acid and/or low doses of γ-irradiation against cisplatin-induced liver injury in rats

The therapeutic efficacy of cisplatin (CIS) is limited owing to its hepatotoxic side effects. The current study aimed to investigate the protective impact of ferulic acid (FA) and low-doses of γ-irradiation (LDR) against CIS-prompted hepatotoxicity in rats. Adult male Swiss albino rats were divided into eight groups: untreated group; FA, LDR, and CIS treated groups; and combinations of one or more of the above treatments. Post-treatment analyses included measuring redox markers like SOD and CAT activity, NO free radical content, and lipid peroxidation in liver tissue. Serum aminotransferase activities were also determined. Additionally, gene transcript levels of liver NF-ҡB-P65, caspase-1, COX-2, and IL-1β were quantified. Moreover, immunohistochemistry for caspase-3 and histopathological examinations were estimated in liver tissue. Our findings revealed increased levels of oxidative stress along with a significant reduction in anti-oxidative responses and a significant increase in serum aminotransferase activities in the CIS-intoxicated group. A similar increase was also observed in COX-2 and IL-1β transcript levels and caspase-3 enzyme activity, besides a decrease in transcript levels of NF-ҡB-p65 and caspase-1, indicating an overall inflammatory trend and an increase in the apoptotic shift. The co-administration of FA and/or treatment with LDR has ameliorated the hepatotoxic effect induced by CIS. The histopathological investigation of liver tissues confirmed this ameliorating action of these adjuvant therapies against CIS toxicity. In conclusion, it is plausible to suggest that the hepatoprotective effects of co-administration of FA and/or LDR against CIS-induced hepatotoxicity are attributed to the possession of anti-oxidative, anti-inflammatory, and anti-apoptotic capabilities.

Choice of biologics in asthma endotypes

PURPOSE OF REVIEW

The aim of this study was to highlight the phenotypes and endotypes of asthma as a tool for selection of the Food and Drug Administration approved biologic therapies.

RECENT FINDINGS

An evolving concept of asthma has led to the identification of distinct phenotypes and endotypes in this disease. Asthma endotypes are defined as the biological mechanism and are often categorized as T2-high and T2-low based on the influence of T helper type 2 (T2) cells and type 2 cytokines, including interleukin (IL)-4, IL-5, IL-9 and IL-13. Biomarkers such as peripheral blood absolute eosinophil count, total IgE, specific IgE and fractional exhaled nitric oxide may be used as indicators of asthma endotypes and help predict response to biologic therapies. There are currently five biologic therapies approved as a treatment option for T2-high asthma: omalizumab, benralizumab, mepolizumab, reslizumab and dupilumab.

SUMMARY

Here, we explore the current understandings of asthma endotypes and review their associated phenotypes. We provide practical and evidence-based guidance for clinicians considering a biologic for asthma add-on maintenance therapy.

Association between aspirin use and lung cancer incidence depends on high-frequency use, bodyweight, and age in U.S. adults

Background

Chemoprevention of cancer with aspirin is controversial as a primary prevention strategy. We sought to investigate the association between aspirin frequency and risk of lung cancer in The Prostate, Lung, Colorectal and Ovarian (PLCO) Cancer Screening Trial.

Methods

Using data from 101,722 participants in PLCO, we used a Cox regression model coupling with propensity score to detect the association between aspirin frequency and lung cancer risk.

Results

High-frequency aspirin use significantly increased risk of lung cancer by 28% compared to no use (HR =1.28; 95% CI, 1.14–1.45; P=3.37×10⁻⁵), especially for current smoker (HR =1.30; 95% CI, 1.07–1.57; P=6.82×10⁻³). However, the increased lung cancer risk due to high-frequency aspirin use significantly decreased with increasing bodyweight (HR_interaction =0.96; 95% CI, 0.94–0.99; P=1.26×10⁻²). Further, for participants with bodyweight <80 kg, high-frequency aspirin use showed an elevated risk at <76 years of age (HR_age<76 =1.47; 95% CI, 1.25–1.73; P=3.81×10⁻⁶). Our study used propensity score under various confounding and stratification analyses by cardio-cerebrovascular status, which all presented similar evidences.

Conclusions

High-frequency aspirin use is associated with the increased risk of lung cancer. Current smoker or people with age <76 years and bodyweight <80 kg should be more cautious to high-frequency aspirin use for lung cancer chemoprevention. This study provides a new insight for lung cancer chemoprevention.

The role of aspirin desensitization followed by oral aspirin therapy in managing patients with aspirin-exacerbated respiratory disease: A Work Group Report from the Rhinitis, Rhinosinusitis and Ocular Allergy Committee of the American Academy of Allergy, Asthma & Immunology

Aspirin-exacerbated respiratory disease (AERD) is characterized by the clinical triad of chronic rhinosinusitis with nasal polyps, asthma, and an intolerance to medications that inhibit the cycloxgenase-1 enzyme. Patients with AERD on average have more severe respiratory disease compared with patients with chronic rhinosinusitis with nasal polyps and/or asthma alone. Although patients with AERD traditionally develop significant upper and lower respiratory tract symptoms on ingestion of cycloxgenase-1 inhibitors, most of these same patients report clinical benefit when desensitized to aspirin and maintained on daily aspirin therapy. This Work Group Report provides a comprehensive review of aspirin challenges, aspirin desensitizations, and maintenance aspirin therapy in patients with AERD. Identification of appropriate candidates, indications and contraindications, medical and surgical optimization strategies, protocols, medical management during the desensitization, and recommendations for maintenance aspirin therapy following desensitization are reviewed. Also included is a summary of studies evaluating the clinical efficacy of aspirin therapy after desensitization as well as a discussion on the possible cellular and molecular mechanisms explaining how this therapy provides unique benefit to patients with AERD.

Interleukin-1β Modulation of the Mechanobiology of Primary Human Pulmonary Fibroblasts: Potential Implications in Lung Repair

Pro-inflammatory cytokines like interleukin-1β (IL-1β) are upregulated during early responses to tissue damage and are expected to transiently compromise the mechanical microenvironment. Fibroblasts are key regulators of tissue mechanics in the lungs and other organs. However, the effects of IL-1β on fibroblast mechanics and functions remain unclear. Here we treated human pulmonary fibroblasts from control donors with IL-1β and used Atomic Force Microscopy to unveil that IL-1β significantly reduces the stiffness of fibroblasts concomitantly with a downregulation of filamentous actin (F-actin) and alpha-smooth muscle (α-SMA). Likewise, COL1A1 mRNA was reduced, whereas that of collagenases MMP1 and MMP2 were upregulated, favoring a reduction of type-I collagen. These mechanobiology changes were functionally associated with reduced proliferation and enhanced migration upon IL-1β stimulation, which could facilitate lung repair by drawing fibroblasts to sites of tissue damage. Our observations reveal that IL-1β may reduce local tissue rigidity by acting both intracellularly and extracellularly through the downregulation of fibroblast contractility and type I collagen deposition, respectively. These IL-1β-dependent mechanical effects may enhance lung repair further by locally increasing pulmonary tissue compliance to preserve normal lung distension and function. Moreover, our results support that IL-1β provides innate anti-fibrotic protection that may be relevant during the early stages of lung repair.

Chronic Rhinosinusitis with Nasal Polyps and Asthma

Patients with chronic rhinosinusitis with nasal polyps (CRSwNP) characterized by a type 2 immune signature often have severe and recurrent disease. Lower airway conditions such as asthma are common comorbidities and share similar pathophysiology. CRSwNP with asthma is characterized by tissue eosinophilia and high local IgE levels. Clinically, CRSwNP with comorbid asthma is associated with more severe sinonasal symptoms and worse quality of life, and it is more difficult to treat both medically and surgically. Asthma in the presence of nasal polyposis is also more difficult to control, being more exacerbation prone, with increased airway obstruction and more extensive eosinophilic inflammation. Aspirin/nonsteroidal anti-inflammatory drug-exacerbated respiratory disease (AERD) is a recognized phenotype of CRSwNP with comorbid asthma. Patients with CRSwNP with comorbid AERD are among those with the most severe and difficult-to-treat disease, and tend to have severe NP. The shared pathophysiology of the upper and lower airways has important implications for both the diagnosis and management of respiratory comorbidities. However, in clinical practice, the nose and lungs are often treated as separate entities. The underlying systemic inflammatory link between CRSwNP and asthma provides a compelling rationale for systemic treatment with novel biologics targeting shared underlying type 2 inflammatory pathways.

NSAID-Exacerbated Respiratory Disease (NERD): From Pathogenesis to Improved Care

Nonsteroidal antiinflammatory drug (NSAID)-exacerbated respiratory disease (NERD) is characterized by moderate-to-severe asthma and a higher prevalence of chronic rhinosinusitis/nasal polyps, but is a highly heterogeneous disorder with various clinical manifestations. Two major pathogenic mechanisms are: (1) overproduction of cysteinyl leukotrienes with dysregulation of arachidonic acid metabolism and (2) increased type 2 eosinophilic inflammation affected by genetic mechanisms. Aspirin challenge is the gold standard to diagnose NERD, whereas reliable in vitro biomarkers have yet not been identified. Therapeutic approaches have been done on the basis of disease severity with the avoidance of culprit and cross-reacting NSAIDs, and when indicated, aspirin desensitization is an effective treatment option. Biologic approaches targeting Type 2 cytokines are emerging as potential therapeutic options. Here, we summarize the up-to-date evidence of pathophysiologic mechanisms and diagnosis/management approaches to the patients with NERD with its phenotypic classification.

Aspirin sensitivity: Lessons in the regulation (and dysregulation) of mast cell function

The idiosyncratic activation of mast cells (MCs) in response to administration of nonselective COX inhibitors is a cardinal feature of aspirin-exacerbated respiratory disease (AERD). Older studies using MC-stabilizing drugs support a critical role for MCs and their products in driving the severe eosinophilic inflammation and respiratory dysfunction that is typical of AERD. Because patients with AERD react to all nonselective COX inhibitors regardless of their chemical structure, the mechanism of MC activation is not caused by classical, antigen-induced cross-linking of IgE receptors. Recent studies in both human subjects and animal models have revealed a complex and multifactorial process culminating in dysregulation of MC function and an aberrant dependency on COX-1-derived prostaglandin E₂ to maintain a tenuous homeostasis. This article reviews the factors most likely to contribute to MC dysregulation in patients with AERD and the potential diagnostic and therapeutic implications.

Prostaglandin EP2 receptor downstream of Notch signaling inhibits differentiation of human skeletal muscle progenitors in differentiation conditions

Understanding the signaling pathways that regulate proliferation and differentiation of muscle progenitors is essential for successful cell transplantation for treatment of Duchenne muscular dystrophy. Here, we report that a γ-secretase inhibitor, DAPT (N-[N-(3,5-difluorophenacetyl-L-alanyl)]-S-phenylglycine tertial butyl ester), which inhibits the release of NICD (Notch intercellular domain), promotes the fusion of human muscle progenitors in vitro and improves their engraftment in the tibialis anterior muscle of immune-deficient mice. Gene expression analysis revealed that DAPT severely down-regulates PTGER2, which encodes prostaglandin (PG) E2 receptor 2 (EP2), in human muscle progenitors in the differentiation condition. Functional analysis suggested that Notch signaling inhibits differentiation and promotes self-renewal of human muscle progenitors via PGE2/EP2 signaling in a cAMP/PKA-independent manner.

Aspirin-exacerbated respiratory disease

Aspirin-exacerbated respiratory disease (AERD) classically presents with severe asthma, nasal polyposis, and respiratory exacerbations in response to cyclooxygenase (COX)-1 inhibition. Recent advances in our understanding of AERD have revealed multiple facets of immune dysregulation, including diminished prostaglandin E2 (PGE₂) function and elevated levels of both cysteinyl leukotrienes (CysLTs) and innate cytokines such as interleukin 33 (IL-33). Inflammatory mediators in AERD heighten the recruitment and activation of innate lymphoid cells type 2 (ILC2), mast cells, eosinophils, and platelet-adherent leukocytes. This contributes to a cyclical pattern of type 2 inflammation. Here, we highlight current understanding of the immunopathogenesis of AERD.

Pro-Inflammatory Response of Bovine Polymorphonuclear Cells Induced by Mycoplasma mycoides subsp. mycoides

Mycoplasma mycoides subsp. mycoides (Mmm) is the etiological agent of contagious bovine pleuropneumonia (CBPP), one of the major diseases affecting cattle in sub-Saharan Africa. Some evidences suggest that the immune system of the host (cattle) plays an important role in the pathogenic mechanism of CBPP, but the factors involved in the process remain largely unknown. The present study aimed to investigate the cell response of bovine polymorphonuclear neutrophils (PMNs) after Mmm in vitro exposure using one step RT-qPCR and Western blotting. Data obtained indicate that gene and protein expression levels of some pro-inflammatory factors already change upon 30 min of PMNs exposure to Mmm. Of note, mRNA expression level in Mmm exposed PMNs increased in a time-dependent manner and for all time points investigated; targets expression was also detected by Western blotting in Mmm exposed PMNs only. These data demonstrate that when bovine PMN cells are triggered by Mmm, they undergo molecular changes, upregulating mRNA and protein expression of specific pro-inflammatory factors. These results provide additional information on host-pathogen interaction during CBPP infection.

NSAID-ERD Syndrome: the New Hope from Prevention, Early Diagnosis, and New Therapeutic Targets

PURPOSE OF REVIEW

This review summarizes the latest information on the appropriate identification, evaluation, and treatment of patients with nonsteroidal anti-inflammatory drug (NSAID)-exacerbated respiratory disease (NSAID-ERD), also known as aspirin-exacerbated respiratory disease (AERD). Within the framework of our understanding of the underlying pathophysiology of NSAID-ERD, we also provide an update regarding new surgical techniques and newly available or upcoming medical therapies that may benefit these patients.

RECENT FINDINGS

There have been considerable developments regarding recommendations for both the extent and timing of sinus surgery for NSAID-ERD. The last few years have also given us several new biologic medications that warrant consideration in the treatment of patients with recalcitrant NSAID-ERD. Further clinical trials are underway to investigate additional medications that may decrease the type 2 inflammation that dominates this disease. Despite the severe lower respiratory inflammation and recurrent nature of the nasal polyps in patients with NSAID-ERD, significant recent advances now afford much-improved quality of life for these patients. Careful collaboration between Allergy/Immunology and Rhinology specialists is imperative to ensure proper treatment of patients with NSAID-ERD.

IL-4/IFN-γ inflammatory cytokine profile induces a deficient regulation of the IL-1β/IL-1RI/EP2/COX-2 pathway in nasal mucosa

BACKGROUND

We hypothesized that the peculiar mixed interleukin-4 (IL-4/Th2) and interferon gamma INF-γ (INF-γ/Th1) inflammatory milieu found in the airways of patients with aspirin-exacerbated respiratory disease (AERD) is responsible for the altered regulation of the IL-1β/IL-1RI-/EP₂/COX-2 autocrine loop also found in these patients. The objective of the study is to demonstrate that IL-4 and INF-γ cytokines, are capable of inducing in healthy nasal mucosa (NM) the dysregulation of the autocrine loop of COX reported in AERD.

SUBJECTS AND METHODS

Fibroblasts were obtained from NM (n = 8). To evaluate the role of IL-4 and IFN-γ on the autocrine loop, fibroblasts were incubated with or without IL-1β, in the presence or absence of IL-4 and/or IFN-γ for 48 h. After this period, the expression of EP₂, EP₃, EP₄, IL-1RI, COX-2 and mPGES-1 was measured by Western blot.

RESULTS

Stimulation of fibroblasts with IL-1β significantly increased the expression of EP₂, but had no effects on EP₃ and EP₄ expression Incubation with IL-4 or IFN-γ alone was not able to modify the expression of any of the components of the autocrine loop. In contrast, co-treatment with IL-4 and IFN-γ was able to significantly inhibit IL-1β-induced EP₂, IL-1RI, COX-2 and mPGES-1.

CONCLUSION

These results suggest that the mixed Th1/Th2 inflammatory pattern found in the airways of AERD patients might be responsible for the altered regulation of the COX pathway also reported in these asthma patients.

High Expression of IL-1RI and EP₂ Receptors in the IL-1β/COX-2 Pathway, and a New Alternative to Non-Steroidal Drugs-Osthole in Inhibition COX-2

BACKGROUND

Osthole (7-methoxy-8-isopentenylcoumarin) is natural coumarin isolated from the fruit of Cnidium monnieri (L.) Cusson, which is commonly used in medical practice of traditional Chinese medicine (TCM) in various diseases including allergies and asthma disorders.

PURPOSE

Osthole was tested for the anti-histamine, anti-allergic, and inhibitory effects of COX-2 (cyclooxygenase-2) in children with diagnosed allergies. Additionally, we hypothesize that stated alterations in children with diagnosed allergies including increased expression of interleukin 1-β receptor type 1 (IL-1 type I) and E-prostanoid (EP) 2 receptors, as well as raised expression, production, and activity of COX-2 and IL-1β in incubated medium are approximately connected. Furthermore, we establish the mechanisms included in the changed regulation of the COX-2 pathway and determine whether osthole may be COX-2 inhibitor in peripheral blood mononuclear cells (PBMCs).

METHOD

PBMCs were obtained from peripheral blood of healthy children (control, n = 28) and patients with diagnosed allergies (allergy, n = 30). Expression of the autocrine loop components regulating PGE₂ production and signaling namely IL-1 type I receptor (IL-1RI), cyclooksygenaze-2 (COX-2), E-prostanoid (EP) 2, and also histamine receptor-1 (HRH-1) was assessed at baseline and after stimulation with histamine, osthole, and a mixture of histamine/osthole 1:2 (v/v). This comprised the expression of histamine receptor 1 (HRH-1), IL-1RI, COX-2, EP₂ receptor, and the secretion of IL-1β and COX-2 in cultured media and sera.

RESULTS

Compared with control group, basal mRNA expression levels of HRH-1, IL-1RI, COX-2, and EP₂ were higher in the allergy group. Histamine-induced EP₂ and COX-2 expression mRNA levels were also increased.

CONCLUSIONS

Osthole successively inhibits PGE₂ and COX-2 mRNA expression. Furthermore, osthole reduces the secretion of COX-2 protein in signaling cellular mechanisms. Changed EP₂ expression in children with allergies provides higher IL-1RI induction, increasing IL-1β capacity to increase COX-2 expression. This effects in higher PGE₂ production, which in turn increases its capability to induce IL-1RI.

Sinus Surgery Is Associated with a Decrease in Aspirin-Induced Reaction Severity in Patients with Aspirin Exacerbated Respiratory Disease

BACKGROUND

Nasal polyps influence the burden of aspirin-exacerbated respiratory disease (AERD) by contributing to eicosanoid production. AERD is diagnosed through graded aspirin challenges. It is not known how sinus surgery affects aspirin challenge outcomes.

OBJECTIVE

To investigate the effects of endoscopic sinus surgery (ESS) on aspirin-induced reaction severity and on the levels of eicosanoids associated with these reactions.

METHODS

Twenty-eight patients with AERD were challenged with aspirin before and 3 to 4 weeks after ESS. Respiratory parameters and plasma and urine levels of eicosanoids were compared before and after challenges.

RESULTS

Before ESS, AERD diagnosis was confirmed in all study patients by aspirin challenges that resulted in hypersensitivity reactions. After ESS, reactions to aspirin were less severe in all patients and 12 of 28 patients (43%, P < .001) had no detectable reaction. A lack of clinical reaction to aspirin was associated with lower peripheral blood eosinophilia (0.1 K/μL [interquartile range (IQR) 0.1-0.3] vs 0.4 K/μL [IQR 0.2-0.8]; P = .006), lower urinary leukotriene E₄ levels after aspirin challenge (98 pg/mg creatinine [IQR 61-239] vs 459 pg/mg creatinine [IQR 141-1344]; P = .02), and lower plasma prostaglandin D₂ to prostaglandin E₂ ratio (0 [±0] vs 0.43 [±0.2]; P = .03), compared with those who reacted.

CONCLUSIONS

Sinus surgery results in decreased aspirin sensitivity and a decrease in several plasma and urine eicosanoid levels in patients with AERD. Diagnostic aspirin challenges should be offered to patients with suspected AERD before ESS to increase diagnostic accuracy. Patients with established AERD could undergo aspirin desensitizations after ESS as the severity of their aspirin-induced hypersensitivity reactions lessens.

MS4A2-rs573790 Is Associated With Aspirin-Exacerbated Respiratory Disease: Replicative Study Using a Candidate Gene Strategy

Aspirin exacerbated respiratory disease (AERD) is a set of diseases of the unified airway, and its physiopathology is related to disruption of the metabolism of arachidonic acid (AA). Genetic association studies in AERD had explored single nucleotide polymorphism (SNPs) in several genes related to many mechanisms (AA metabolism, inflammation, drug metabolism, etc.) but most lack validation stages in second populations. Our aim is to evaluated whether contribution to susceptibility of SNPs reported in other populations are associated with AERD in Mexican Mestizo patients. We developed a replicative study in two stages. In the first, 381 SNPs selected by fine mapping of associated genes, (previously reported in the literature), were integrated into a microarray and tested in three groups (AERD, asthma and healthy controls -HC-) using the GoldenGate array. Results associated to risk based on genetic models [comparing: AERD vs. HC (comparison 1, C1), AERD vs. asthma (C2), and asthma vs. HC (C3)] were validated in the second stage in other population groups using qPCR. In the first stage, we identified 11 SNPs associated with risk in C1.The top SNPs were ACE-rs4309C (p = 0.0001) and MS4A2-rs573790C (p = 0.0002). In C2, we detected 14 SNPs, including ACE-rs4309C (p = 0.0001). In C3, we found MS4A2-rs573790C (p = 0.001). Using genetic models, C1 MS4A2-rs57370 CC (p = 0.001), and ACE-rs4309 CC (p = 0.002) had associations. In C2 ACE-rs4309 CC (p = 0.0001) and C3 MS4A2-rs573790 CC (p = 0.001) were also associate with risk. In the second stage, only MS4A2-rs573790 CC had significance in C1 and C3 (p = 0.008 and p = 0.03). We concluded that rs573790 in the MS4A2 gene is the only SNP that supports an association with AERD in Mexican Mestizo patients in both stages of the study.

Immunological mechanisms underlying chronic rhinosinusitis with nasal polyps

INTRODUCTION

Chronic rhinosinusitis with nasal polyps (CRSwNP) is a common and quality-of-life impacting disorder, with an underlying immunological mechanism similar to other conditions such as eosinophilic asthma or atopic eczema. Areas covered: This review article summarizes the most recent evidence on the main immunological mechanisms involved in the pathogenesis and the perpetuation of CRSwNP, with a particular focus on the key role of epithelium-derived inflammation as a consequence of the interaction with the airborne environment. Expert commentary: The increase in knowledge of the immunology of CRSwNP leads to the development of therapeutical strategies based upon the use of biologic agents that, according to a personalized and precision medicine approach, will provide each single patient with the most suitable immunological treatment.

Prostaglandin E2 triggers cytochrome P450 17α hydroxylase overexpression via signal transducer and activator of transcription 3 phosphorylation and promotes invasion in endometrial cancer

Prostaglandin E2 (PGE2) is the most common prostaglandin in the human body, meaning that its malfunction impacts on the development of numerous diseases. Prostaglandin E synthase 2 (PTGES2) is involved in the synthesis of PGE2. In the present study, immunohistochemistry of PTGES2 was performed in 152 patients with endometrial cancer and in 66 patients with normal endometria. The results indicate a notable association among increased expression of PTGES2 and age (P=0.0092) and the depth of myometrial invasion (P<0.0001). Reverse transcription-quantitative polymerase chain reaction and western blot analysis demonstrated that cytochrome P450 17α hydroxylase (CYP17), an enzyme for androgen synthesis, is overexpressed following PGE2 stimulation via signal transducer and activator of transcription 3 (STAT3) phosphorylation. ELISA also detected increased androgen (testosterone) secretion. Further invasion of endometrial cancer cells was induced at high androgen levels and when CYP17 was overexpressed. Furthermore, the present study observed that CYP17 is overexpressed via STAT3 phosphorylation in endometrial cancer cells, which grow at a high concentration of PGE2, resulting in increased androgen secretion. Concentrations of estrogen and progesterone were not elevated, while the concentration of androgens was. Overall, a high concentration of androgens caused increased invasion of endometrial cancer cells. A high concentration of androgens, which is initiated by a high expression of PTGES2 and a high concentration of PGE2, is an important promoter of myometrial invasion in endometrial cancer.

The family of the interleukin-1 receptors

The extracellular forms of the IL-1 cytokines are active through binding to specific receptors on the surface of target cells. IL-1 ligands bind to the extracellular portion of their ligand-binding receptor chain. For signaling to take place, a non-binding accessory chain is recruited into a heterotrimeric complex. The intracellular approximation of the Toll-IL-1-receptor (TIR) domains of the 2 receptor chains is the event that initiates signaling. The family of IL-1 receptors (IL-1R) includes 10 structurally related members, and the distantly related soluble protein IL-18BP that acts as inhibitor of the cytokine IL-18. Over the years the receptors of the IL-1 family have been known with many different names, with significant confusion. Thus, we will use here a recently proposed unifying nomenclature. The family includes several ligand-binding chains (IL-1R1, IL-1R2, IL-1R4, IL-1R5, and IL-1R6), 2 types of accessory chains (IL-1R3, IL-1R7), molecules that act as inhibitors of signaling (IL-1R2, IL-1R8, IL-18BP), and 2 orphan receptors (IL-1R9, IL-1R10). In this review, we will examine how the receptors of the IL-1 family regulate the inflammatory and anti-inflammatory functions of the IL-1 cytokines and are, more at large, involved in modulating defensive and pathological innate immunity and inflammation. Regulation of the IL-1/IL-1R system in the brain will be also described, as an example of the peculiarities of organ-specific modulation of inflammation.

Role of lipid mediators and control of lymphocyte responses in type 2 immunopathology

Type 2 immunopathology is a cardinal feature of allergic diseases and involves cooperation between adaptive immunity and innate effector responses. Virtually all cell types relevant to this pathology generate leukotriene and/or prostaglandin mediators that derive from arachidonic acid, express receptors for such mediators, or both. Recent studies highlight prominent functions for these mediators in communication between the innate and adaptive immune systems, as well as amplification or suppression of type 2 effector responses. This review focuses on recent advances and insights, and highlights existing and potential therapeutic applications of drugs that target these mediators or their receptors, with a special emphasis on their regulation of the innate and adaptive lymphocytes relevant to type 2 immunopathology.

Aspirin exacerbated respiratory disease: Current topics and trends

Aspirin-exacerbated respiratory disease is a chronic and treatment-resistant disease, characterized by the presence of eosinophilic rhinosinusitis, nasal polyposis, bronchial asthma, and nonsteroidal anti-inflammatory drugs hypersensitivity. Alterations in arachidonic acid metabolism may induce an imbalance between pro-inflammatory and anti-inflammatory substances, expressed as an overproduction of cysteinyl leukotrienes and an underproduction of prostaglandin E2. Although eosinophils play a key role, recent studies have shown the importance of other cells and molecules in the development of the disease like mast cells, basophils, lymphocytes, platelets, neutrophils, macrophages, epithelial respiratory cells, IL-33 and thymic stromal lymphopoietin, making each of them promissory diagnostic and treatment targets. In this review, we summarize the most important clinical aspects of the disease, including the current topics about diagnosis and treatment, like provocation challenges and aspirin desensitization. We also discuss recent findings in the pathogenesis of the disease, as well as future trends in diagnosis and treatment, including monoclonal antibodies and a low salicylate diet as a treatment option.

Physiopathology and genetics in aspirin-exacerbated respiratory disease

INTRODUCTION

Aspirin-exacerbated respiratory disease (AERD) is a clinical entity characterized by hypersensitivity to aspirin leading to asthma and chronic rhinosinusitis with nasosinusal polyposis. The pathophysiology of the disease involves disruption at the level of arachidonic acid metabolism. Therefore, genetic association studies have been focused on the genes coding this pathway. As other mechanisms involved in the genesis of the disease were elucidated, the corresponding genes were also explored.

AIM

To describe the association reported in the literature between gene polymorphisms involved in the pathophysiology or therapeutic processes of AERD.

RESULTS

There is a genetic association between polymorphisms of genes involved in the synthesis of proteins related to arachidonic acid metabolism (LTC4S, ALOX5), antigen presentation (HLA), inflammation (IL5, IL17), and aspirin metabolism (CYP2C19).

CONCLUSIONS

Genetic association research in AERD has evaluated studies of SNPs in metabolic pathways related to arachidonic acid. Recently, whole genome analysis strategies have allowed the detection of new genetic variants that were previously not considered. Furthermore, these studies have identified SNPs that are associated with inflammatory processes, which could serve as diagnostic markers or predictors of the therapeutic response.

Advances in mechanisms of allergic disease in 2016

This review highlights advances in mechanisms of allergic disease, particularly type 2 innate lymphoid cells; T_H2 lymphocytes; eicosanoid regulation of inflammation; extracellular vesicles in allergic responses; IL-33; microbiome properties, especially as they relate to mucosal barrier function; and a series of findings concerning the allergic inflammatory cells eosinophils, basophils, and mast cells. During the last year, mechanistic advances occurred in understanding type 2 innate lymphoid cells, particularly related to their response to ozone, involvement with experimental food allergy responses, and regulation by IL-33. Novel ways of regulating T_H2 cells through epigenetic regulation of GATA-3 through sirtuin-1, a class III histone deacetylase, were published. The understanding of eicosanoid regulation of inflammation increased and focused on additional properties of phospholipase A₂ and the role of prostaglandin D₂ and its receptors and inhibitory prostaglandin E₂ pathways. Mechanisms through which extracellular vesicles are released and contribute to allergic responses were reported. There was a deeper appreciation of mucosal barrier function, the epithelial alarmin IL-33, and the microbiome. Finally, there were advances concerning allergic inflammatory cells (mast cells, basophils, and eosinophils) that will undoubtedly have an effect on disease understanding and new therapeutic strategies.

Aspirin and Nonsteroidal Antiinflammatory Drugs Hypersensitivity and Management

Aspirin and nonsteroidal antiinflammatory drugs (NSAIDs) are widely used in the United States and throughout the world for a variety of indications. Several unique hypersensitivity syndromes exist to this class of medications, making them one of the common reasons for consultation to the allergist. The lack of any laboratory-based diagnostic studies to assist in identifying the culprits in these reactions make evaluation of aspirin and NSAID hypersensitivity challenging. Identifying patients appropriate for oral challenge and/or desensitization protocols is the standard pragmatic approach to this issue when it arises.

Update on Aspirin-Exacerbated Respiratory Disease

Aspirin-exacerbated respiratory disease (AERD) is an acquired disease characterized by chronic eosinophilic airway inflammation with underlying dysregulation of arachidonic acid metabolism. The purpose of this paper is to review the latest developments in our understanding of the underlying pathophysiology including the role of eosinophils, mast cells, innate lymphoid cells (ILC₂), and platelets. Clinical features such as respiratory reactions induced by alcohol, aggressive nasal polyposis, and anosmia will allow for earlier recognition of these patients in clinical practice. The current state of the art management of AERD will be addressed including the ongoing central role for aspirin desensitization and high-dose aspirin therapy.

Clinical Characteristics of Patients with Chronic Rhinosinusitis with Nasal Polyps, Asthma, and Aspirin-Exacerbated Respiratory Disease

BACKGROUND

Aspirin-exacerbated respiratory disease (AERD) comprises the triad of chronic rhinosinusitis with nasal polyps (CRSwNP), asthma, and intolerance to inhibitors of the cyclooxygenase-1 (COX-1) enzyme. The prevalence of AERD remains unclear, and few studies have compared the clinical characteristics of patients with AERD to those with CRSwNP alone, asthma alone, or both CRSwNP and asthma.

OBJECTIVE

To determine the prevalence of AERD within a tertiary care setting, and to identify unique clinical features that could distinguish these patients from those with both CRSwNP and asthma or with CRSwNP alone.

METHODS

Electronic medical records of patients at Northwestern in Chicago, Illinois, were searched by computer algorithm and then manual chart review to identify 459 patients with CRSwNP alone, 412 with both CRSwNP and asthma, 171 with AERD, and 300 with asthma only. Demographic and clinical features including sex, atopy, and sinus disease severity were characterized.

RESULTS

The prevalence of AERD among patients with CRSwNP was 16%. Patients with AERD had undergone 2-fold more sinus surgeries (P < .001) and were significantly younger at the time of their first surgery (40 ± 13 years) than were patients with CRSwNP (43 ± 14 years; P < .05). Atopy was significantly more prevalent in patients with AERD (84%) or asthma (85%) than in patients with CRSwNP (66%, P < .05). More patients with AERD (13%) had corticosteroid-dependent disease than patients with both CRSwNP and asthma (4%, P < .01) or asthma (1%, P < .001).

CONCLUSIONS

AERD is common among patients with CRSwNP; even though patients with AERD have CRSwNP and asthma, the clinical course of their disease is not the same as of patients who have CRSwNP and asthma but are tolerant to COX-1 inhibitors.

Eicosanoid Mediators in the Airway Inflammation of Asthmatic Patients: What is New?

Lipid mediators contribute to inflammation providing both pro-inflammatory signals and terminating the inflammatory process by activation of macrophages. Among the most significant biologically lipid mediators, these are produced by free-radical or enzymatic oxygenation of arachidonic acid named "eicosanoids". There were some novel eicosanoids identified within the last decade, and many of them are measurable in clinical samples by affordable chromatography-mass spectrometry equipment or sensitive immunoassays. In this review, we present some recent advances in understanding of the signaling by eicosanoid mediators during asthmatic airway inflammation. Eicosanoid profiling in the exhaled breath condensate, induced sputum, or their metabolites measurements in urine is complementary to the cellular phenotyping of asthmatic inflammation. Special attention is paid to aspirin-exacerbated respiratory disease, a phenotype of asthma manifested by the most profound changes in the profile of eicosanoids produced. A hallmark of this type of asthma with hypersensitivity to non-steroid anti-inflammatory drugs (NSAIDs) is to increase biosynthesis of cysteinyl leukotrienes on the systemic level. It depends on transcellular biosynthesis of leukotriene C₄ by platelets that adhere to granulocytes releasing leukotriene A₄. However, other abnormalities are also reported in this type of asthma as a resistance to anti-inflammatory activity of prostaglandin E₂ or a robust eosinophil interferon-γ response resulting in cysteinyl leukotrienes production. A novel mechanism is also discussed in which an isoprostane structurally related to prostaglandin E₂ is released into exhaled breath condensate during a provoked asthmatic attack. However, it is concluded that any single eicosanoid or even their complex profile can hardly provide a thorough explanation for the mechanism of asthmatic inflammation.