Differential mediator release from basophils of allergic and non-allergic asthmatic patients after stimulation with anti-IgE and C5a

Adipokines and Cysteinyl Leukotrienes in the Pathogenesis of Asthma

Background. The prevalence of obesity has increased dramatically over the last decades, and its association with asthma is being increasingly recognized. Aims. Our hypothesis is that increased leptin and decreased adiponectin levels in obese subjects play a direct role in regulating inflammation in asthmatics. We wanted to examine the hypothesis that cysteinyl leukotrienes (cys-LT), inflammatory mediators that are regulated by adipokines, are involved in the pathogenesis of asthma. Methods. We studied a population of asthmatics and nonasthmatics, who in turn were divided into obese and nonobese categories. We examined leptin and its ratio to adiponectin, in asthmatics and nonasthmatics, with and without obesity. In addition, we measured cys-LT levels in exhaled breath condensate (EBC) and in peripheral blood monocytes (PBM) in these groups. Results. Leptin levels were increased in obese asthmatics compared to obese nonasthmatics. The leptin/adiponectin (L/A) ratio was higher in obese asthmatics compared to obese nonasthmatics. EBC cys-LT levels were elevated in asthmatics compared to nonasthmatics. Discussion. Proinflammatory adipokines, released from adipose tissue, may promote an asthma phenotype through enhanced cys-LT production that may result in more prevalent and difficult to control airway disease.

Hypersensitivity to Aspirin and other NSAIDs: Diagnostic Approach in Patients with Chronic Rhinosinusitis

Hypersensitivity to nonsteroidal anti-inflammatory drugs (NSAIDs) associated with chronic rhinosinusitis (CRS) and/or asthma comprises a distinct clinical syndrome referred to as NSAIDs exacerbated respiratory disease (NERD). Patients with NERD tend to have more severe course of both upper (CRS and nasal polyps) and lower airway (asthma) diseases and are usually recalcitrant to conventional treatment modalities. Diagnosing and phenotyping of patients with NERD are critical for prevention of drug-induced adverse reactions and open novel options for management of underlying chronic airway inflammatory diseases. Diagnosis of NERD is based on detailed clinical history confirmed by challenge with aspirin, but new diagnostic approaches are currently being developed. This review article focuses on the diagnostic approach to a patient with CRS and hypersensitivity to NSAIDs, emphasizing the importance of diagnosis for proper patient's management.

C5a-induced in vitro basophil activation in patients with chronic urticaria: a pilot study

BACKGROUND

Complement component 5a (C5a) might be involved in the formation of wheals in patients with chronic urticaria (CU). We sought to compare the in vitro responsiveness of basophils to C5a in patients with CU and in a control group.

METHODS

Basophil surface expression of activation marker CD63 induced by C5a, anti-FcepsilonRI mAb or anti-IgE pAb was measured using flow cytometry in 17 patients with CU and in 10 healthy controls.

RESULTS

Patients with CU showed significantly greater basophil CD63 surface expression induced by C5a (median [interquartile range]; 16.4% [13-25.1]; P = 0.011) than the group of healthy controls (10.7% [7.2-16.8]). In contrast, basophil CD63 response to anti-IgE and anti-FcepsilonRI was lower in the CU group (12.3% [6-36.3]; 25.9% [12.5-60.5]) than in the control group (51.7% [6.7-84.3]; 62.1% [9.7-89.2]), although not statistically significant.

CONCLUSION

Results of this pilot study suggest that patients with CU might have an enhanced basophil response to stimulation with C5a, indicating that further studies in CU basophil responsiveness are needed.

Allergens induce enhanced bronchoconstriction and leukotriene production in C5 deficient mice

Background

Previous genetic analysis has shown that a deletion in the complement component 5 gene-coding region renders mice more susceptible to allergen-induced airway hyperresponsiveness (AHR) due to reduced IL-12 production. We investigated the role of complement in a murine model of asthma-like pulmonary inflammation.

Methods

In order to evaluate the role of complement B10 mice either sufficient or deficient in C5 were studied. Both groups of mice immunized and challenged with a house dust extract (HDE) containing high levels of cockroach allergens. Airways hyper-reactivity was determined with whole-body plesthysmography. Bronchoalveolar lavage (BAL) was performed to determine pulmonary cellular recruitment and measure inflammatory mediators. Lung homogenates were assayed for mediators and plasma levels of IgE determined. Pulmonary histology was also evaluated.

Results

C5-deficient mice showed enhanced AHR to methylcholine challenge, 474% and 91% increase above baseline Penh in C5-deficient and C5-sufficient mice respectively, p < 0.001. IL-12 levels in the lung homogenate (LH) were only slightly reduced and BAL IL-12 was comparable in C5-sufficient and C5-deficient mice. However, C5-deficient mice had significantly higher cysteinyl-leukotriene levels in the BAL fluid, 1913 +/- 246 pg/ml in C5d and 756 +/- 232 pg/ml in C5-sufficient, p = 0.003.

Conclusion

These data demonstrate that C5-deficient mice show enhanced AHR due to increased production of cysteinyl-leukotrienes.

Aspirin-triggered 15-HETE generation in peripheral blood leukocytes is a specific and sensitive Aspirin-Sensitive Patients Identification Test (ASPITest)

BACKGROUND

We have previously demonstrated that aspirin triggers specific generation of 15-hydroxyeicosateraenoic acid (15-HETE) from nasal polyp epithelial cells and peripheral blood leukocytes (PBL) from aspirin-sensitive (AS) but not aspirin-tolerant (AT) patients with asthma/rhinosinusitis. The goal of this study was to assess the diagnostic value of ASA-induced 15-HETE generation measurement to identify AS patients.

METHODS

PBL were obtained from 43 AS patients with asthma and rhinosinusitis, 35 AT asthmatics and 17 healthy control (HC) subjects. PBL were incubated with 2-200 muM aspirin (ASA) and 15-HETE release was measured in cell supernatants with competitive ELISA.

RESULTS

Unstimulated PBL from all three groups of patients generated similar amount of 15-HETE. Incubation with 200 microM ASA resulted in an increase in an 15-HETE generation (mean increase +421%) in AS-asthmatics but small and nonsignificant response in AT-asthmatics or control subjects. Receiver operating curve (ROC) analysis revealed that the sensitivity of the test for confirmation of ASA-sensitivity was 83% and the specificity 82%. Positive predictive value was 0.79 and negative predictive value was 0.86. Naproxen induced a significant increase in 15-HETE only in some AS-asthmatics, but not in AT-asthmatics.

CONCLUSION

Our data demonstrate that ASA-induced 15-HETE generation by PBL is a specific and sensitive aspirin-sensitive patients identification test (ASPITest).

Novel C5a regulators in inflammatory disease

Complement is part of the innate immune system, acting to protect the host from microorganisms such as bacteria, and other foreign and abnormal cells. Although primarily protective, complement activation can also cause damage to the host. In a number of inflammatory diseases, including rheumatoid arthritis and dermatitis, there is excessive and inappropriate complement activation. Many of the toxic effects seen in these conditions are attributable to the excessive production of the anaphylatoxin C5a, which may contribute to both the initiation and progression of the disease. Therefore, the regulation of C5a production and modulation of its function are good pharmacological targets in these disorders. As yet, there are no effective agents for the therapeutic regulation of C5a in routine clinical practice. This review describes the role of C5a in inflammatory disease, animal models used to study C5a-related effects, and current strategies aimed at regulating C5a. There is also a discussion of the strengths and weaknesses of these approaches, and an outline of the likely progress of this class of drugs in the future.

The flow-cytometric determination of basophil activation induced by aspirin and other non-steroidal anti-inflammatory drugs (NSAIDs) is useful for in vitro diagnosis of the NSAID hypersensitivity syndrome

BACKGROUND

Hypersensitivity reactions to non-steroidal anti-inflammatory drugs (NSAIDs), manifested by cutaneous symptoms and/or airway manifestations represent 20-25% of all hypersensitivity reactions to drugs. Today, it is still claimed that no in vitro diagnostic tests exist for that condition and that the only way to confirm the diagnosis is a provocation challenge.

OBJECTIVE

The objective of this study was to assess whether NSAIDs may provoke blood basophil activation in vitro in such patients, as detected by a flowcytometric technique.

METHODS

Sixty NSAID hypersensitive patients (38 with cutaneous, 20 with airway and two with cutaneous and airway symptoms) and 30 control patients (15 asthmatics) were selected. Their hypersensitivity was confirmed by documented history indicating at least two clinical episodes to two or more different NSAIDs or by positive oral provocation challenge. Isolated buffy coat leukocytes were stimulated in vitro with aspirin, paracetamol, metamizol, diclofenac, and naproxen. The percentage of activated basophils was evaluated by an anti-CD63.

RESULTS

Aspirin showed a sensitivity of 43.3%, a specificity of 100%, a positive predictive value of 100% and a negative predictive value of 99.4%. For the other NSAIDs, the sensitivity and specificity values were: for paracetamol 11.7% and 100%, for metamizol 15% and 100%, for diclofenac 43.3% and 93.3% and for naproxen 54.8% and 74.1%. When considering the first four NSAIDs, the global sensitivity raised to 63.3% and specificity to 93.3%. If the number of tests is to be limited for practical reasons, the combination of acetylsalicylic acid and diclofenac at two concentrations yields a sensitivity of 58.3% and a specificity of 93.3%.

CONCLUSIONS

Flowcytometric determinations of basophil activation following stimulation with NSAIDs show a high sensitivity (60-70%) with specificity above 90%. So this test may help avoiding some cumbersome and dangerous provocation challenges.

A new combined test with flowcytometric basophil activation and determination of sulfidoleukotrienes is useful for in vitro diagnosis of hypersensitivity to aspirin and other nonsteroidal anti-inflammatory drugs

BACKGROUND

We assessed whether nonsteroidal anti-inflammatory drugs (NSAIDs) may provoke blood basophil activation in vitro in aspirin- and NSAID-hypersensitive patients, as detected by a flowcytometric technique using the CD63 marker--flowcytometric basophil activation test (FAST) assay--in addition to the sulfidoleukotriene (sLT) release--the cellular allergen stimulation test (CAST).

METHODS

Sixty aspirin- and/or NSAID-hypersensitive patients were studied. Thirty control patients without history and negative provocation challenge were also included. The percentage of activated basophils after in vitro stimulation with NSAIDs at 3 different concentrations was evaluated by an anti-CD63 phycoerythrin conjugate (FAST assay) and the amount of sLTs released in the cell supernatant by ELISA (CAST assay).

RESULTS

For aspirin, the FAST indicated a sensitivity of 41.7%, a specificity of 100%, a positive predictive value of 100% and a negative predictive value of 99.4%; for paracetamol 11.7 and 100%, for metamizol 15 and 100%, for diclofenac 43.3 and 93.3%, and for naproxen 54.8 and 74.1%. Many patients showed positive tests to more than 1 NSAID. When considering the first 4 NSAIDs, the global sensitivity increased to 66.7%, while the specificity remained at 93.3%. The addition of the CAST results still increased the sensitivity up to 73.3%, but with a decrease of the specificity to 71.4%.

CONCLUSIONS

The FAST shows a high percentage of positive reactions, which may reach 60-70% when 4 NSAIDs are tested and even 88% when the test is performed within 1 month of the last clinical drug exposure and reaction. The test has a high specificity above 90%. The addition of sLT determinations yields additional information in a few isolated cases. It is suggested that this test, when properly used, may help avoid some cumbersome and dangerous provocation challenges.

Basophil CD63 expression assay on highly sensitized atopic donor leucocytes-a useful method in chronic autoimmune urticaria

BACKGROUND

The autoimmune subclass of chronic idiopathic urticaria (CU) has been characterized by the occurrence of biologically relevant IgG antibodies against the IgE molecule or the alpha chain of the high-affinity Fcepsilon receptor (FcepsilonRIalpha) on basophils and mast cells. These antibodies are usually detected by autologous serum skin testing and confirmed by histamine release studies, immunoblotting, or enzyme-linked immunosorbent assay, but not always.

OBJECTIVES

To detect autoantibodies to the FcepsilonRIalpha in sera of CU patients by a modified serum-induced basophil activation test measured by flow cytometry (FCM) and to evaluate the relationship between the in vitro functional test, the autologous serum skin test (ASST), and the serum levels of IgE, eosinophil cationic protein (ECP) and antithyroid antibodies.

METHODS

Sera of 30 patients with CU and 26 patients with systemic autoimmune diseases (systemic lupus erythematosus, dermatomyositis) were tested for CD63 activation marker expression on basophils by FCM. Leucocytes from two highly sensitized atopic donors (D(A1,) D(A2)) and one non-atopic donor (D(NA)) were incubated with patients' sera and double-labelled with anti-IgE and anti-CD63 antibodies. Subsequently, the percentage of CD63-expressing basophils was determined by using FCM. In all CU patients an ASST was carried out and the serum IgE, and ECP levels and antithyroid antibodies were evaluated.

RESULTS

Twelve patients had a positive ASST and 14 patients a positive CD63 expression assay. There was a strong correlation between the ASST and CD63 assay. Sera from patients with systemic autoimmune diseases did not raise positive CD63 expression on basophils. There was a moderate negative correlation between the occurrence of atopic serum markers (IgE, ECP) and the ability of sera to induce CD63 expression on basophil cells of D(A2) (P < 0.05). The female sex was preponderant and antithyroid antibodies were more frequent.

CONCLUSIONS

Our new technical observation demonstrates that basophils of highly sensitized atopic donors can be successfully used without priming with IL-3 for the in-vitro flow cytofluorimetric diagnosis of CU. With this investigation the characterization of the autoimmune origin of CU is based on an objective in vitro technique.

In vitro allergy diagnosis: should we follow the flow?

During the last 5 years, an increasing number of studies have demonstrated that flow cytometric quantification of in vitro basophil activation can be a quite performant and reliable tool to measure IgE-dependent allergen-specific responses in allergic patients. So far, most assays have used CD63 as a basophil activation marker and native allergen extracts for stimulation. However, other basophil markers and recombinant allergens have recently been introduced. The technique has been applied for the diagnosis of allergy to pollen, house dust mite, food, natural rubber latex, hymenoptera venom and drugs. In addition, the technique has proven to be useful in non-IgE-mediated reactions such as hypersensitivity to drugs as well as detection of auto-antibodies in chronic urticaria. This review will focus on some specific issues: (1) principles of flow cytometric analysis of in vitro-activated basophils, (2) general technical aspects of the technique (including passive sensitization), (3) clinical applications and (4) recommendations for further development and evaluation of the technique.