Inmaculada Andreu

In vitro evaluation of IgE-mediated hypersensitivity reactions to quinolones

To cite this article: Aranda A, Mayorga C, Ariza A, Doña I, Rosado A, Blanca‐Lopez N, Andreu I, Torres MJ. In vitro evaluation of IgE‐mediated hypersensitivity reactions to quinolones. Allergy 2011; 66: 247–254.

Hypersensitivity reactions to quinolones.

Purpose of review The purpose of this review is to examine in detail the new advances in the pathomechanisms and diagnosis of immediate and nonimmediate hypersensitivity reactions to quinolones, as well as analyze cross-reactivity among different quinolones. Recent findings Hypersensitivity reactions to quinolones, especially anaphylactic reactions, have become more common in the past decade. This phenomenon could be related to their increased consumption. Although attempts have been made to standardize skin testing, the diagnosis of immediate hypersensitivity reactions to quinolones is mainly based on drug provocation. Some in-vitro, radioimmunoassay and basophil activation tests have also been used for diagnostic purposes, with results indicating that they could be complementary to in-vivo tests. Cross-reactivity seems to exist between first and second-generation quinolones, with lower levels with the third and fourth generations. However, no general rules exist for predicting cross-reactivity and it needs to be analyzed patient by patient. Nonimmediate hypersensitivity reactions also exist, especially maculopapular exanthema and fixed drug eruptions, and a T-cell mechanism has been demonstrated. Summary Over the past decade the number of hypersensitivity reactions to quinolones has increased. These reactions can be severe and diagnosis difficult to confirm. Although new in-vitro tests hold promise, drug provocation testing remains the most frequently used and reliable diagnostic method.

Hypersensitivity Reactions to Non-Steroidal Anti-Inflammatory Drugs

NSAIDs are the most important group of drugs involved in hypersensitivity drug reactions, and include heterogeneous compounds with very different chemical structures. These reactions can be IgE dependent (immediate reactions), T cell-mediated (non-immediate), or induced by a non-specific immunological mechanism related with the blocking of the COX-1 enzyme and the shunting to the lipooxygenase pathway (cross-intolerant reactions). Cutaneous symptoms are the most frequent, with ibuprofen, naproxen and diclofenac being common culprit drugs worldwide, although others can be involved because patterns of consumption and exposure rates vary between countries. A very important proportion of immunological reactions are immediate, with urticaria and anaphylaxis being the typical clinical manifestations. Non-immediate reactions comprise a number of heterogeneous entities ranging from mild exanthema to severe TEN or DRESS syndrome, as well as organ-specific reactions such as hepatitis or pneumonitis. Cross-intolerant reactions appear to non-chemically related drugs, and involve respiratory airways, skin or both. In vivo diagnostic tests are based on the capacity of the skin to respond to the culprit drug, but their sensitivity is in many instances rather low. The approach for in vitro testing consists of either detecting specific IgE antibodies or studying the proliferation of T lymphocytes toward the eliciting drug. No appropriate tests are yet available for the in vitro validation of cross-intolerance reactions, although techniques based on the stimulation of basophils have been proposed. Based on these findings, the diagnostic approach is often based on the controlled administration of the drug to assess tolerance. In this work we review current knowledge on hypersensitivity reactions to NSAIDs, including diagnostic approach and genetic studies.

Photophysical Probes To Assess the Potential of Cholic Acid Aggregates as Drug Carriers

The two enantiomers of the nonsteroidal antiinflammatory drug naproxen and of its methyl ester have been selected as representative probes with markedly different hydrophobicity to assess the potential of cholic acid aggregates as drug carriers by means of photophysical techniques. The different distribution of the probes between bulk solution and aggregates has been assessed by quenching of their singlet and triplet excited states by iodide and nitrite anions, respectively. This straightforward photophysical methodology can, in principle, be extended to a variety of drugs containing a photoactive chromophore.

Fluoroquinolone Photodegradation Influences Specific Basophil Activation

Fluoroquinolones (FQs) are photoreactive drugs, but it is not known whether laboratory light exposure can influence the induction of photoproducts and modify in vitro test results. The basophil activation test (BAT) has proven to be useful for evaluating immunoglobulin E (IgE)-mediated hypersensitivity to FQs, with a higher percentage of positive responders with ciprofloxacin (CIP) than with moxifloxacin (MOX). We studied the effect of laboratory light on CIP and MOX degradation, and drug-protein conjugate formation, and its influence on the BAT for evaluating IgE-mediated hypersensitivity to FQs. The results showed an important decrease in fluorescence emission intensity under light compared to dark conditions for MOX, and that BAT positivity was lower in light (17.9%) than in dark (35.7%) conditions. No changes were found for CIP in either fluorescence emission intensity or BAT results (46.4% in both conditions). We can conclude that light exposure is a critical factor in BAT results when photolabile drugs like MOX are used. Therefore, light is important when interpreting in vitro results.

Chiral discrimination in the intramolecular abstraction of allylic hydrogens by benzophenone triplets

Using two diastereomeric compounds containing benzophenone and olefin units, significant chiral discrimination has been found in all the photophysical and photochemical processes involved in intramolecular hydrogen abstraction: overall quenching of benzophenone triplets, actual hydrogen abstraction step and π-quenching.

Synergistic Effect between Amoxicillin and TLR Ligands on Dendritic Cells from Amoxicillin-Delayed Allergic Patients

Amoxicillin, a low-molecular-weight compound, is able to interact with dendritic cells inducing semi-maturation in vitro. Specific antigens and TLR ligands can synergistically interact with dendritic cells (DC), leading to complete maturation and more efficient T-cell stimulation. The aim of the study was to evaluate the synergistic effect of amoxicillin and the TLR2, 4 and 7/8 agonists (PAM, LPS and R848, respectively) in TLR expression, DC maturation and specific T-cell response in patients with delayed-type hypersensitivity (DTH) reactions to amoxicillin. Monocyte-derived DC from 15 patients with DTH to amoxicillin and 15 controls were cultured with amoxicillin in the presence or absence of TLR2, 4 and 7/8 agonists (PAM, LPS and R848, respectively). We studied TLR1-9 gene expression by RT-qPCR, and DC maturation, lymphocyte proliferation and cytokine production by flow cytometry. DC from both patients and controls expressed all TLRs except TLR9. The amoxicillin plus TLR2/4 or TLR7/8 ligands showed significant differences, mainly in patients: AX+PAM+LPS induced a decrease in TLR2 and AX+R848 in TLR2, 4, 7 and 8 mRNA levels. AX+PAM+LPS significantly increased the percentage of maturation in patients (75%) vs. controls (40%) (p=0.036) and T-cell proliferation (80.7% vs. 27.3% of cases; p=0.001). Moreover, the combinations AX+PAM+LPS and AX+R848 produced a significant increase in IL-12p70 during both DC maturation and T-cell proliferation. These results indicate that in amoxicillin-induced maculopapular exanthema, the presence of different TLR agonists could be critical for the induction of the innate and adaptive immune responses and this should be taken into account when evaluating allergic reactions to these drugs.

Metabolomics in Drug Intolerance

Adverse drug reactions appear during the clinical use of a drug and constitute a health problem, as they are an important cause of patient morbidity and mortality. In addition, they constitute a major drawback for drug development. Intolerance processes occurring after administration of low drug doses are known as idiosyncratic reactions or as hypersensitivity reactions; the most commonly accepted mechanism for immunological activation is the hapten hypothesis. Most drugs are not reactive per se towards proteins, hence in a number of cases bioactivation seems to be a prerequisite for adduct formation and the subsequent hypersensitivity reaction. Although biotransformation is normally associated with a decreased toxicity, metabolites are sometimes more toxic and reactive than the parent drug. Drug metabolizing enzymes develop their activities especially in liver, where reactive metabolites bind to proteins inducing hepatotoxicity, whereas in skin keratinocytes exhibit the highest biotransformation capability. In the present review, some specific examples of the toxicological consequences of drug biotransformation are given. They include nimesulide, metamizol, celecoxib, paracetamol, dapsone, sulfamethoxazole, amodiaquine, nevirapine, troglitazone, zileuton, felbamate, panadiplon, benzbromarone, fipexide and flutamide. In general, these examples are taken from the recent scientific literature, mostly published during the last decade.

Enhanced photosafety of cinacalcet upon complexation with serum albumin.

Cinacalcet (CIN) is a calcimimetic drug, which contains a naphthalene chromophore and binds almost quantitatively to human serum albumin (HSA). In the present work, the excited states of CIN have been characterized in order to obtain relevant information about complexation of CIN with HSA. The fluorescence spectrum in acetonitrile, at λ(exc) = 290 nm, displayed two bands with maxima at 332 and 439 nm, assigned to the monomer and exciplex emission. Upon protonation of the amino group, the exciplex band disappeared, with a concomitant increase of the monomer emission intensity. Time-resolved fluorescence evidenced an intramolecular dynamic quenching, attributed to exciplex formation and/or photoinduced electron transfer, in agreement with the favorable thermodynamics predicted by the Rehm-Weller equations. Diffusion controlled dynamic quenching of CINH(+) fluorescence by oxygen was observed. The emission properties in PBS were similar to those obtained for CINH(+) in acetonitrile. Laser flash photolysis (LFP) of CIN and CINH(+) in acetonitrile/N(2), at λ(exc) = 308 nm, gave rise to the naphthalene-like triplet excited states, with maxima at 420 nm and lifetimes of 4 and 7 μs; they were efficiently quenched by oxygen. No significant singlet excited state interaction was observed in CINH(+)/HSA complexes, as revealed by the emission spectra, which were roughly explained taking into account the relative contributions of drug and protein in the absorption spectra. Upon LFP of the complexes, triplet excited states were generated; the decays monitored at 420 nm were satisfactorily fitted using a function containing two monoexponential terms, corresponding to a short-lived (τ(1) = 8 μs) and a long-lived (τ(2) = 37 μs) component. This indicates that the drug is incorporated into two different binding sites of HSA. Despite the long triplet lifetimes of the CINH(+)/HSA complexes, the rate constant of quenching by oxygen was found to be 2 orders of magnitude lower than that determined in acetonitrile, which can be attributed to the relative slower diffusion rates in this microheterogeneous system. Therefore, the protein microenvironment protects cinacalcet from attack by oxygen; this prevents the phototoxic effects caused by formation of singlet oxygen and results in an enhanced photosafety of the drug.

Generation of reactive intermediates in photoallergic dermatitis

Purpose of reviewPhotosensitivity disorders are cutaneous reactions caused or amplified in their severity by sunlight, normally ultraviolet radiation (UVA or UVB). These reactions appear when xenobiotics are topically or systemically administered, and the individuals are exposed to solar or artificial light. Recent findingsPhotoallergic reactions seem to be initiated by covalent binding of the photosensitizer to a skin protein, forming adducts capable of interacting with the immune system. The most frequent reactions of this type (photoallergic dermatitis) are induced by drugs and mediated by T cells. Diagnosis of photoallergy requires identification of the responsible agent, which is not always clear-cut. Photopatch testing is the method of choice for definitive diagnosis. SummaryIn the current review, some specific examples of photoallergic xenobiotics are given. They include nonsteroidal anti-inflammatory drugs, antibiotics, platelet aggregation inhibitors, and sunscreens. In general, they are taken from the scientific literature published during the last decade, with particular emphasis on the most recent articles. The focus is on the mechanistic aspects, specifically on the generation of reactive intermediates capable of reacting with proteins.