Clinical and immunological determinants of severe/refractory asthma (SRA): association with Staphylococcal superantigen-specific IgE antibodies

BACKGROUND

Demographic and immunological determinants of severe refractory asthma (SRA) are not well characterized. Because Staphylococcus aureus enterotoxins with superantigenic activity have been associated with upper and lower airway inflammation, we aimed to evaluate the association of sensitization to Staphylococcal enterotoxins with asthma severity and various asthma phenotypes.

METHODS

The study included 109 patients with SRA diagnosed according to the American Thoracic Society Workshop 2000, and 101 patients with nonsevere asthma, followed for at least 12 months. Specific IgE to Staphylococcus enterotoxins and total IgE and eosinophil cationic protein concentrations were measured in serum with immunoassays.

FINDINGS

A significant risk for severe asthma was associated with female gender [Odds Ratio (OR) = 2.04], history of wheezing in childhood (OR = 2.47), presence of hypersensitivity to aspirin (OR = 1.96) and with body mass index (OR = 3.08). The mean level of enterotoxin-specific IgE was 3-fold higher in patients with severe asthma when compared to patients with nonsevere asthma (P = 0.01). Serum-specific IgE to enterotoxins was significantly associated with low respiratory function parameters (FEV₁, FEV₁/FVC and MEF 25/75) and increased airway reversibility in response to albuterol. The presence of specific IgE to enterotoxin carried a significant risk for patients to have serum total IgE level above 100 kU/l (OR = 7.84).

INTERPRETATION

Specific immunological response to enterotoxins is associated with clinical and immunological parameters of asthma severity, suggesting a role for Staphylococcal enterotoxins in the asthma pathogenesis.

CRTH2 mediates the activation of human Th2 cells in response to PGD(2) released from IgE/anti-IgE treated nasal polyp tissue

BACKGROUND

Mast cells release mediators upon stimulation that contribute to the pathogenesis of chronic airway disease, including the recruitment and activation of Th2 lymphocytes. The objective was to determine the involvement of prostaglandin D(2) (PGD(2)) and its receptors in the chemotaxis of Th2 cells, using nasal polyp tissue.

METHODS

Tissue explants from ten patients with nasal polyposis were incubated with RPMI alone or RPMI containing IgE/anti-IgE for 30 min. Some samples were treated with diclofenac to inhibit the production of PGD(2). Supernatants were assayed for PGD(2) content and for their ability to promote human Th2 cell chemotaxis in the presence and absence of a CRTH2 antagonist. Transcript levels of D protanoid receptor type 1 (DP(1)), chemoattractant receptor-homologous receptor expressed on Th2 cells (CRTH2) and PGD(2) synthase were analysed by real time PCR.

RESULTS

Increased release of PGD(2) by nasal polyp tissue treated with IgE/anti-IgE was significantly inhibited by preincubation of the tissue with diclofenac. Transcript levels of PGD(2) synthase, DP(1) and CRTH2 receptors increased after stimulation with IgE/anti-IgE. Supernatants from IgE/anti-IgE-stimulated nasal polyp tissue caused significantly increased chemotaxis of Th2 cells. The levels of PGD(2) produced and the degree of Th2 cell chemotaxis were highly correlated. Diclofenac inhibited the production of Th2 cell chemotactic activity, and the chemotactic effect of the supernatant on Th2 cells was inhibited by the CRTH2 antagonist ramatroban.

CONCLUSION

These data suggest that in immunologically activated nasal polyp tissue, PGD(2) produced by mast cells promotes the migration of Th2 cells through a CRTH2 dependent mechanism.

Eicosanoid metabolism and eosinophilic inflammation in nasal polyp patients with immune response to Staphylococcus aureus enterotoxins

BACKGROUND

Staphylococcus aureus-derived enterotoxins (SEs) have been implicated in the pathogenesis of airway inflammatory diseases, especially nasal polyposis. However, the exact role of these molecules in the regulation of eicosanoid synthesis in this pathology remains unexplored. We studied the possible impact of SE-induced immune responses on the eicosanoid production in nasal polyp (NP) patients.

METHODS

Tissue sample homogenates from NP patients, with (NP-SEs[+]) and without detectable IgE-antibodies to SEs (NP-SEs[-]; ImmunoCap system), were assayed for IL-5, myeloperoxidase, leukotriene CJD4/E4 (LTC4/D4/E4), LTB4, lipoxin A4, total IgE, and eosinophil cationic protein.

RESULTS

Inflammatory makers, eicosanoids, and total IgE were significantly increased in NP-SEs(+) compared with NP-SEs(-) tissues, with the exception of myeloperoxidase, which was similar in both groups. Eicosanoid concentrations correlated to IL-5 and eosinophil cationic protein; however, only cys-leukotriene levels correlated with IgE-antibodies to SEs, independently of allergy and asthma.

CONCLUSION

Eicosanoid synthesis is up-regulated in polyp tissue of patients with immune response to SEs and seems to be related to the inflammatory reaction induced by these enterotoxins.

Expression of eicosanoid receptors subtypes and eosinophilic inflammation: implication on chronic rhinosinusitis

Background

Eicosanoid receptors are G-protein-coupled receptors playing an important immunomodulatory role in airway diseases. However, there is little information on the expression of these receptors and their link with eosinophilic inflammation in paranasal sinus diseases. We aimed with this study to investigate the tissue expression of leukotrienes and prostaglandin E2 receptors in chronic rhinosinusitis patients and the link of this regulation with eosinophilic inflammation.

Methods

Samples were prepared from nasal tissue of patients with chronic rhinosinusitis without nasal polyps (CRS, n = 11), with nasal polyps (CRS-NP, n = 13) and healthy subjects (Controls, n = 6). mRNA expression of CysLT₁, CysLT₂, BLT₁, BLT₂, E-prostanoid receptors (EP₁, EP₂, EP₃, EP₄) and sol-IL-5Rα was determined by real-time PCR. Concentrations of PGE2, LTC4/D4/E4, LTB4 and sol-IL-5Rα were determined by ELISA and of ECP by ImmunoCap. Protein expression and tissue localization of eicosanoid receptors and activated eosinophils were evaluated by immunohistochemistry.

Results

CysLT₁ mRNA expression was significantly increased in CRS-NP compared to CRS and controls, and CRS compared to controls, whereas CysLT₂ mRNA was enhanced in both CRS groups without differences between them. Levels of both receptors correlated to the number of activated eosinophils, sol-IL-5Rα, ECP and LTC₄/D₄/E₄ concentrations in the disease groups. PGE₂ protein concentrations and prostanoid receptors EP₁ and EP₃ were down-regulated in the CRS-NP tissue vs. CRS and controls, whereas EP₂ and EP₄ expression was enhanced in CRS and CRS-NP patients vs. controls. No differences in BLT receptors were observed between patients and controls.

Conclusion

CyLTs receptors are up-regulated in nasal polyp tissue and their expression correlate with eosinophilic inflammation supporting previous results. Eicosanoid receptors mRNA pattern observed suggests that down-regulation of EP₁ and EP₃ in CRS-NP and up-regulation EP₂ and EP₄ in CRS and CRS-NP groups may have some role in the development of the diseases and their regulation may not be directly linked to eosinophil activation but involve post-transcriptional events mainly related to other inflammatory cell sources.

Prostaglandin, leukotriene, and lipoxin balance in chronic rhinosinusitis with and without nasal polyposis

BACKGROUND

Upper airway diseases and especially the aspirin hypersensitivity syndrome have been linked to changes in the arachidonic acid cascade; however, the specificity of these changes and their relation to inflammatory reactions in these diseases still remain controversial.

OBJECTIVE

We aimed to study the tissue eicosanoid production in 3 subgroups of patients with chronic rhinosinusitis (CRS) and control subjects and to correlate it with the severity of inflammation and clinical manifestation of aspirin sensitivity.

METHODS

Samples were prepared from sinonasal tissue of patients with CRS with (CRS-NP group, n = 13) and without nasal polyposis (CRS group, n = 11), sinonasal tissue of patients with nasal polyposis and aspirin sensitivity (CRS-ASNP group, n = 13), and normal nasal mucosa from healthy subjects (NM group, n = 8). Real-time PCR was applied for mRNA quantification of COX-2, 5-lipoxygenase, leukotriene C 4 synthase, and 15-lipoxygenase. Enzyme immunoassays were used to measure IL-5, eosinophil cationic protein, and eicosanoid (leukotriene [LT] C 4 , LTD 4 , and LTE 4 ; lipoxin A 4 ; and prostaglandin E 2 [PGE 2 ]) concentrations.

RESULTS

COX-2 mRNA and PGE 2 concentrations were similar in the CRS and NM groups but significantly decreased in nasal polyp tissue, especially in the CRS-ASNP group. LTC 4 synthase, 5-lipoxygenase mRNA, LTC 4 , LTD 4 , and LTE 4 concentrations increased with disease severity among the patient groups. 15-Lipoxygenase and lipoxin A 4 concentrations were increased in all CRS groups compared with in the NM group but were significantly downregulated in the CRS-ASNP group when compared with the CRS-NP group. IL-5 and eosinophil cationic protein were increased in both groups of nasal polyp tissue compared with in the NM and CRS groups and correlated directly with LTC 4 , LTD 4 , and LTE 4 concentrations and inversely with PGE 2 concentrations.

CONCLUSION

Changes of tissue eicosanoid metabolism do occur in CRS, even in the absence of clinical aspirin sensitivity, and these changes appear to be related to the severity of eosinophilic inflammation.