Mepolizumab targets multiple immune cells in aspirin-exacerbated respiratory disease.

BACKGROUND: Eosinophilic asthma and nasal polyposis are hallmarks of aspirin-exacerbated respiratory disease (AERD), and IL-5 inhibition has been shown to provide therapeutic benefit. However, IL-5Rα is expressed on many cells in addition to eosinophils, and the mechanisms by which IL-5 inhibition leads to clinical benefit in eosinophilic asthma and nasal polyposis are unlikely to be due exclusively to antieosinophil effects. OBJECTIVE: We sought to identify the mechanisms by which anti-IL-5 treatment with mepolizumab improves respiratory inflammation in AERD. METHODS: The clinical characteristics, circulating granulocytes, nasal scraping transcripts, eosinophilic cationic protein, tryptase, and antibody levels, and urinary and nasal eicosanoid levels were measured for 18 subjects with AERD who were taking mepolizumab and compared with those of 18 matched subjects with AERD who were not taking mepolizumab. RESULTS: Subjects taking mepolizumab had significantly fewer peripheral blood eosinophils and basophils, and those cells that remained had higher surface CRTH2 expression than did the cells from subjects not taking mepolizumab. Nasal prostaglandin F2α, prostaglandin D2 metabolites, leukotriene B4, and thromboxane levels were lower in subjects taking mepolizumab, as were urinary levels of tetranor-prostaglandin D2 and leukotriene E4. The nasal epithelial cell transcripts that were overexpressed among subjects with AERD who were taking mepolizumab were enriched for genes involved in tight junction formation and cilium organization. Nasal and urinary prostaglandin E2, tryptase, and antibody levels were not different between the 2 groups. CONCLUSION: IL-5 inhibition in AERD decreases production of inflammatory eicosanoids and upregulates tight junction-associated nasal epithelial cell transcripts, likely due to decreased IL-5 signaling on tissue mast cells, eosinophils, and epithelial cells. These direct effects on multiple relevant immune cells contribute to the mechanism of benefit afforded by mepolizumab.

Elevated Urine Leukotriene E4 Is Associated With Worse Objective Markers in Nasal Polyposis Patients.

OBJECTIVES: Urine leukotriene E4 (uLTE4) is a biomarker of leukotriene synthesis and is elevated in patients with aspirin-exacerbated respiratory disease (AERD). It can also be useful to help delineate aspirin-tolerant chronic rhinosinusitis with nasal polyposis (CRSwNP) patients from AERD patients. The purpose of this study is to determine if uLTE4 biomarker levels are associated with objective and subjective markers of disease severity in patients with CRSwNP. METHODS: A retrospective analysis of CRSwNP patients who underwent uLTE4 testing was completed to determine the association of uLTE4 levels to markers of disease severity. uLTE4 levels, as well as presenting subjective (Sinonasal Outcome Test 22 [SNOT22] scores, asthma control test [ACT] scores) and objective data (Lund-Mackay CT score, spirometry and lab values) were collected. RESULTS: Among the 157 CRSwNP patients who met inclusion criteria, uLTE4 levels were associated with history of asthma (P < .001), aspirin sensitivity (P < .001), worse Lund-Mackay CT scores (P = .002) and other objective markers of disease severity including serum IgE (P = .05), presenting blood eosinophil level (P < .001), and the highest recorded eosinophil level (P < .001). In subgroup analysis, associations of uLTE4 to disease markers had stronger correlations in the aspirin sensitive CRSwNP group (R range 0.31-0.52) than the aspirin tolerant CRSwNP group (R range -0.30-0.24). uLTE4 levels were not associated with subjective symptom scores (SNOT22 and ACT scores). CONCLUSION: Elevated uLTE4 biomarker levels are associated with worsened objective markers of disease severity in CRSwNP patients but not patient-reported symptom measures. LEVEL OF EVIDENCE: 3 Laryngoscope, 131:961-966, 2021.

Diagnostic Utility of Urinary LTE4 in Asthma, Allergic Rhinitis, Chronic Rhinosinusitis, Nasal Polyps, and Aspirin Sensitivity.

BACKGROUND: Urinary leukotriene E4 (LTE4) is a well-validated marker of the cysteinyl leukotriene pathway, and LTE4 elevation has been described in conditions such as asthma, aspirin sensitivity, and chronic rhinosinusitis (CRS). There have been a number of reports investigating the role of spot urine LTE4 to predict aspirin sensitivity; however, variability in urinary LTE4 may affect the accuracy of this approach. OBJECTIVE: Here, we explored the utility of 24-hour urinary LTE4 in 5 clinical diagnoses of allergic rhinitis, asthma, chronic rhinosinusitis with nasal polyps (CRSwNP), CRS without nasal polyps, and aspirin sensitivity. METHODS: This was a retrospective review of patients who had 24-hour quantification of urinary LTE4 by a clinically validated liquid chromatography tandem mass spectrometry method and their assigned diagnoses after assessment and clinical care. RESULTS: Twenty-four-hour urinary LTE4 elevations were seen in those with asthma and those with CRSwNP but influenced by underlying aspirin sensitivity. Elevation in LTE4 was significant in those with CRSwNP after adjusting for aspirin sensitivity. Allergic rhinitis was not associated with elevated LTE4 excretion. Receiver operator characteristic analysis of 24-hour urinary LTE4 showed that a cutoff value of 166 pg/mg Cr suggested the presence of history of aspirin sensitivity with 89% specificity, whereas a cutoff value of 241 pg/mg Cr discriminated "challenge-confirmed" aspirin-sensitive subjects with 92% specificity. CONCLUSIONS: Elevated 24-hour excretion of urinary LTE4 is a reliable and simple test to identify aspirin sensitivity in patients with respiratory diagnoses.

Thymic stromal lymphopoietin controls prostaglandin D2 generation in patients with aspirin-exacerbated respiratory disease.

BACKGROUND: Prostaglandin (PG) D2 is the dominant COX product of mast cells and is an effector of aspirin-induced respiratory reactions in patients with aspirin-exacerbated respiratory disease (AERD). OBJECTIVE: We evaluated the role of the innate cytokine thymic stromal lymphopoietin (TSLP) acting on mast cells to generate PGD2 and facilitate tissue eosinophilia and nasal polyposis in patients with AERD. METHODS: Urinary eicosanoid levels were measured in aspirin-tolerant control subjects and patients with AERD. Nasal polyp specimens from patients with AERD and chronic rhinosinusitis were analyzed by using quantitative PCR, Western blotting, and immunohistochemistry. Human cord blood-and peripheral blood-derived mast cells were stimulated with TSLP in vitro to assess PGD2 generation. RESULTS: Urinary levels of a stable PGD2 metabolite (uPGD-M) were 2-fold higher in patients with AERD relative to those in control subjects and increased further during aspirin-induced reactions. Peak uPGD-M levels during aspirin reactions correlated with reductions in blood eosinophil counts and lung function and increases in nasal congestion. Mast cells sorted from nasal polyps expressed PGD2 synthase (hematopoietic PGD2 synthase) mRNA at higher levels than did eosinophils from the same tissue. Whole nasal polyp TSLP mRNA expression correlated strongly with mRNA encoding hematopoietic PGD2 synthase (r = .75), the mast cell-specific marker carboxypeptidase A3 (r = .74), and uPGD-M (r = 0.74). Levels of the cleaved active form of TSLP were increased in nasal polyps from patients with AERD relative to those in aspirin-tolerant control subjects. Recombinant TSLP induced PGD2 generation by cultured human mast cells. CONCLUSIONS: Our study demonstrates that mast cell-derived PGD2 is a major effector of type 2 immune responses driven by TSLP and suggests that dysregulation of this innate system contributes significantly to the pathophysiology of AERD.

Urinary leukotrienes in patients with nasal polyposis.

OBJECTIVES: To compare urinary leukotriene E4 (ULT) level in patients with nasal polyposis (NP) with and without aspirin intolerance and allergic rhinitis (AR), and correlate it with disease severity. STUDY DESIGN AND SETTING: Prospective study from November 2005 to November 2006. Patients with NP (n = 30) and AR (n = 35) were included. The concentration of ULT was measured in both groups. Oral provocation test with aspirin was performed to patients with NP. ULT level between both groups was compared and correlated with NP disease severity. RESULTS: ULT concentration was elevated on NP and AR. The patients with NP and aspirin intolerance (n = 4) presented higher levels of ULT compared to aspirin-tolerant patients. Leukotriene concentration was not correlated with NP severity. CONCLUSIONS: Patients with NP and aspirin intolerance have increased ULT excretion; thus their measurement can be used as an indicator of arachidonic acid metabolism alteration.

Aspirin induced asthma (AIA) with nasal polyps has the highest basal LTE4 excretion: a study vs AIA without polyps, mild topic asthma, and normal controls.

UNLABELLED: Cysteinil Leukotrienes (LTs) are products of the arachidonic acid cascade which are synthetised by 5-lipoxigenase in inflammatory cells, particularly in eosinophils. Urinary leukotriene E4 concentration (LTE4), that reflects the whole body production of cysteinil-leukotrienes, is particularly increased in patients with aspirin-intolerant asthma (AIA). Aim of the present study was to assess basal urinary LTE4 levels from AIA patients with nasal polyps to those from AIA patients with only rhinitis (without polyps), and those from mild atopic asthmatics and normal controls. SUBJECTS & METHODS: 34 normal subjects (N; 19 - 57y, FEV1 = 102.1% pred. +/- 8.2 sd; negative MCh challenge; negative prick test); 39 mild-persistent atopic asthmatics (A; 18-66y, FEV1 = 92.1 %pred. +/- 14.6 sd; PD20 FEV1 = 380.7mcg +/- 481.2 sd); 24 subjects with AIA with rhinitis (AIA/R; 18 - 56y, FEV1 = 71.6%pred +/- 15.5 sd; reversibility = 15.1% bsln +/- 2.1 sd after salbutamol 200mg), and 10 subjects with AIA and nasal polyposis (AIA/NP; 22-49 y; FEV1 = 70.6%pred. +/- 7.1 sd; reversibility = 13.2% bsln +/- 1.6 sd after salbutamol 200 microg) were studied. After their informed consent, urine were collected in the morning for the LTE4 quantitative immunoenzimatic assay (pg/mg creatinine; Cayman Chemical, Ann Arbour, Mi, USA). STATISTICS: Wilcoxon signed rank test was used, and p<0.05 accepted as the lowest level of statistical significance. RESULTS: AIA/NP subjects had the highest levels of urinary LTE4 (432.3 pg/mg +/- 88.1 sd) compared to AIA/R (330.7 pg/mg +/- 72.3s, p < 0.01), to A (129.1 pg/mg +/- 74.8sd, p < 0.001), and to N controls (66.5 pg/mg +/- 20.6 sd, p < 0.001). Moreover, urinary LTE4 levels measured in AIA/R subjects proved significantly higher than those measured in A (p < 0.001) and in N controls (p<0.001), while LTE4 levels in A proved significantly higher than those in N controls (p<0.001). Furthermore, basal LTE4 levels seem inversely related to those of basal FEV1 (102.1 % pred. +/- 8.2sd in N, 92.1 % pred +/- 14.6 sd in A, 71.6 % pred. +/- 15.5 sd in AIA/R, 70.6 % pred +/- 7.1 sd in AIA/P, respectively). Respiratory function in the two sub-groups of AIA patients proved reduced than in atopic asthmatics (p<0.001) and in normal controls (p < 0.001), even though the difference between these two subgroups of subjects did not reach the statistical significance. CONCLUSIONS: Cys-LTs confirm their relevant pathogenetic role in AIA, but also in early stages of atopic asthma. Urinary LTE4 exexcretion proves directly proportional to the extent of nasal structural changes occurring in ASA-intolerant asthmatics, being subjects with nasal polyps those with the highest LTE4 values, immediately followed by those with hypertrophic rhinitis. Routinary measurements of urinary LTE4 should be regarded as a sensitive indicator in monitoring the clinical evolution of nasal involvement in AIA.