Mechanisms of aspirin desensitization

Aspirin desensitization in NSAID-exacerbated respiratory disease and its outcomes in the clinical course of asthma: A systematic review of the literature and meta-analysis

Background

Nonsteroidal anti-inflammatory drug-exacerbated respiratory disease (NERD) might benefit from aspirin desensitization (AD) as an alternative treatment to standard care. However, there is conflicting evidence regarding its role in bronchial symptoms and asthma exacerbations.

Objective

To analyze the clinical effects of AD in terms of lung function, systemic and inhaled steroid use, the frequency of acute asthma exacerbations, and adverse effects in patients with NERD and asthma.

Methodology

We identified randomized clinical trials (RCTs) from PubMed, EMBASE, SCOPUS, and EBSCO. We also searched the RCT references for additional studies. Studies comparing AD to placebo in patients with a previous history of pulmonary symptoms triggered by ASA or other NSAIDs or with a positive provocation test to ASA were included.

Primary results

Five studies with 210 participants with NERD were included in this review. The study duration ranged from 3 to 6 months. Overall, the risk of bias across the included RCTs was low. We identified 3 studies evaluating lung function, 2 of which reported a significant improvement in FEV1 in the AD group after 6 months, while the other reported no difference among the treatments. Due to high heterogeneity, we did not pool the results. The remaining primary outcomes were reported only in a single study each, hindering their interpretation. Secondary outcomes revealed reduced symptom and medication scores in patients with AD.

Conclusions

Due to the small number of studies included in this systematic review, conclusions should be made with caution. AD shows a trend towards improving lung function (FEV1) following 6 months of treatment, although no conclusions can be made regarding the use of corticosteroids or the frequency of acute exacerbations. AD appears to reduce both symptom and medication scores. Additional RCTs are needed to fully assess the efficacy of AD in reducing bronchial symptoms in patients with NERD.

Objective and subjective sinonasal and pulmonary outcomes in aspirin desensitization therapy: A prospective cohort study

OBJECTIVE

Aspirin exacerbated respiratory disease (AERD) patients are challenging to manage with sinonasal and pulmonary symptoms refractory to maximal medical and surgical therapies. Our objective was to comprehensively examine objective and validated, disease-specific subjective sinonasal and pulmonary outcomes of aspirin (ASA) desensitization therapy in this patient population.

METHODS

Prospective cohort study at an academic tertiary center. AERD patients with a history of chronic rhinosinusitis with nasal polyposis (CRSwNP), prior diagnosis of asthma, and a history of ASA sensitivity were eligible for inclusion. Patients underwent ASA desensitization using an established institutional protocol and continued on a 650mg twice daily maintenance dose. Baseline Sinonasal Outcome Test (SNOT-22) and Asthma Control Questionnaire (ACQ) responses, acoustic rhinometry, peak flow readings, and endoscopic scoring of nasal polyps were recorded prior to desensitization and after 6months of maintenance therapy.

RESULTS

Twelve patients were recruited for participation and underwent desensitization. Eight patients continued maintenance therapy and follow up at 6months. Prior to desensitization, patients reported bothersome sinonasal symptoms with a median SNOT-22 score of 30.0±34.5 (interquartile range (IQR)). There was significant improvement after 6months of maintenance therapy to a median SNOT-22 score of 18.5±17.3 (p=0.025, Wilcoxon signed rank test). Acoustic rhinometry, endoscopic scores, ACQ and forced expiratory volume values remained stable at 6months.

CONCLUSIONS

AERD patients may benefit from ASA desensitization with subjective sinonasal symptom improvement at 6months and stable asthma and objective sinonasal measures. Further discussion is needed in the otolaryngology community regarding ASA desensitization in AERD management.

The Role and Immunobiology of Eosinophils in the Respiratory System: a Comprehensive Review

The eosinophil is a fully delineated granulocyte that disseminates throughout the bloodstream to end-organs after complete maturation in the bone marrow. While the presence of eosinophils is not uncommon even in healthy individuals, these granulocytes play a central role in inflammation and allergic processes. Normally appearing in smaller numbers, higher levels of eosinophils in the peripheral blood or certain tissues typically signal a pathologic process. Eosinophils confer a beneficial effect on the host by enhancing immunity against molds and viruses. However, tissue-specific elevation of eosinophils, particularly in the respiratory system, can cause a variety of short-term symptoms and may lead to long-term sequelae. Eosinophils often play a role in more commonly encountered disease processes, such as asthma and allergic responses in the upper respiratory tract. They are also integral in the pathology of less common diseases including eosinophilic pneumonia, allergic bronchopulmonary aspergillosis, hypersensitivity pneumonitis, and drug reaction with eosinophilia and systemic symptoms. They can be seen in neoplastic disorders or occupational exposures as well. The involvement of eosinophils in pulmonary disease processes can affect the method of diagnosis and the selection of treatment modalities. By analyzing the complex interaction between the eosinophil and its environment, which includes signaling molecules and tissues, different therapies have been discovered and created in order to target disease processes at a cellular level. Innovative treatments such as mepolizumab and benralizumab will be discussed. The purpose of this article is to further explore the topic of eosinophilic presence, activity, and pathology in the respiratory tract, as well as discuss current and future treatment options through a detailed literature review.

Contemporary management of chronic rhinosinusitis with nasal polyposis in aspirin-exacerbated respiratory disease: an evidence-based review with recommendations

BACKGROUND

Chronic rhinosinusitis (CRS) in aspirin-exacerbated respiratory disease (AERD) represents a recalcitrant form of sinonasal inflammation for which a multidisciplinary consensus on patient management has not been reached. Several medical interventions have been investigated, but a formal comprehensive evaluation of the evidence has never been performed. The purpose of this article is to provide an evidence-based approach for the multidisciplinary management of CRS in AERD.

METHODS

A systematic review of the literature was performed and the guidelines for development of an evidence-based review with recommendations were followed. Study inclusion criteria included: adult population >18 years old; CRS based on published diagnostic criteria, and a presumptive diagnosis of AERD. We focused on reporting higher-quality studies (level 2 or higher) when available, but reported lower-quality studies if the topic contained insufficient evidence. Treatment recommendations were based on American Academy of Otolaryngology (AAO) guidelines, with defined grades of evidence and evaluation of research quality and risk/benefits associated with each treatment.

RESULTS

This review identified and evaluated the literature on 3 treatment strategies for CRS in AERD: dietary salicylate avoidance, leukotriene modification, and desensitization with daily aspirin therapy.

CONCLUSION

Based on the available evidence, dietary salicylate avoidance and leukotriene-modifying drugs are options following appropriate treatment with nasal corticosteroids and saline irrigation. Desensitization with daily aspirin therapy is recommended following revision endoscopic sinus surgery (ESS).

Upper airways in aspirin-exacerbated respiratory disease

PURPOSE OF REVIEW

This review updates the status of chronic rhinosinusitis with nasal polyps (CRSwNP) in aspirin-exacerbated respiratory disease (AERD) in the contexts of epidemiology, diagnosis, pathogenesis, and treatment.

RECENT FINDINGS

Recent studies have shown that prostaglandin E₂ (PGE₂) deficiency induces an AERD phenotype in PGE₂ synthase-1 knock-out mice and also PGE₂ resistance in granulocytes of AERD patients. The numbers of platelet-adherent leukocytes increase in AERD patients, enhancing production of cysteinyl leukotrienes (CysLTs) via transcellular metabolism of arachidonate. INF-γ released from eosinophils of the sinus tissue of AERD patients promotes eosinophil maturation, increases leukotriene-associated gene expression, and releases CysLTs. The serum periostin level has been suggested to be a useful biomarker predicting the AERD/CRSwNP phenotype. Aspirin desensitization was reported to decrease the levels of CD4⁺ T cell-derived cytokines, including INF-γ and IL-10, in line with the newly defined role of INF-γ in AERD.

SUMMARY

Recent findings further support the notion that arachidonic acid metabolism is dysregulated in AERD patients. This is reflected by resistance to PGE₂, overproduction of CysLTs by enhanced numbers of platelet-adherent leukocytes, and cellular stimulation by INF-γ released from eosinophils. Aspirin desensitization may be a useful treatment option in AERD patients exhibiting recalcitrant CRSwNP.

Aspirin desensitization: useful treatment for chronic rhinosinusitis with nasal polyps (CRSwNP) in aspirin-exacerbated respiratory disease (AERD)?

Aspirin intolerance syndrome is due to disturbances in the arachidonic acid metabolism implicating both the lipoxygenase and cyclooxygenase pathways. This results in imbalances of eicosanoid, leukotriene and prostaglandin synthesis. Thus, preinflammatory cysteinyl leukotrienes increase and antiinflammatory prostaglandins (PG) such as PGE2 decrease. Clinically, intolerance reactions to nonsteroidal antiinflammatory drugs (NSAIDs) can lead to different clinical manifestations; five phenotypes of the aspirin intolerance syndrome are listed in the ENDA classification. Aspirin-exacerbated respiratory disease (AERD) is the most common phenotype characterized by an eosinophil-dominated inflammatory disease of the airways that presents clinically with nasal polyps, chronic sinusitis and bronchial asthma. About 34 % of patients with aspirin-induced asthma and rhinosinusitis are thought to have AERD. Important biochemical findings in many AERD patients are increased basal leukotriene levels (at least in cell cultures) that excessively increase after intake of COX-1 inhibitors. Aspirin desensitization uses the repetitive application of aspirin to induce a tolerance to NSAIDs, especially COX-1 inhibitors. After a dose-increase phase reaching a threshold dose, a dose-continuation phase is performed. For application, the nasal, bronchial, oral and intravenous routes have been described. Aspirin desensitization has been proven to be efficacious and safe and was able to reduce the need for other medications in AERD patients.

Aspirin desensitization in patients with aspirin-induced and aspirin-tolerant asthma: a double-blind study

BACKGROUND

Numerous open trials have demonstrated the beneficial clinical effects of aspirin desensitization (AD) in patients with aspirin-induced asthma (AIA). These beneficial effects might be attributable to aspirin's potent anti-inflammatory properties, but that supposition requires further corroboration.

OBJECTIVE

We sought to compare the clinical and biochemical responses to chronic oral AD in 20 patients with AIA and 14 patients with aspirin-tolerant asthma (ATA). All of the patients had chronic rhinosinusitis and nasal polyposis, and these responses were investigated in a pilot, double-blind, placebo-controlled study.

METHODS

Twelve patients with AIA and 6 patients with ATA were randomly assigned to receive 624 mg of aspirin, and 8 patients with AIA and 8 patients with ATA received placebo. Both aspirin and placebo were administered once daily for 6 months. Nasal symptoms, Sino-Nasal Outcome Test (SNOT20) scores, peak nasal inspiratory flows, Asthma Control Questionnaire scores, spirometric parameters, peak expiratory flows, blood eosinophilia, and corticosteroid doses were assessed on a monthly basis. Levels of urinary leukotriene E4 and the stable plasma prostaglandin (PG) D2 metabolite 9α,11β-PGF2 were evaluated at baseline and after 1, 3, 5, and 6 months.

RESULTS

Only the patients with AIA subjected to AD reported improvements in smell and reductions in sneezing and nasal blockade. The SNOT20 and Asthma Control Questionnaire scores of these patients decreased, and their peak nasal inspiratory flows increased. The dosages of inhaled corticosteroids were reduced. There were no changes in leukotriene E(4) or 9α,11β-PGF(2) levels after AD.

CONCLUSION

The clinically beneficial effects of AD on nasal and bronchial symptoms occurred only in the patients with AIA.