Endothelial cell apoptosis in severe drug-induced bullous eruptions

Stevens-Johnson syndrome and toxic epidermal necrolysis: follow-up of pulmonary function after remission

BACKGROUND

Acute-stage specific bronchial epithelial detachment has been described in 27% of patients with Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN).

OBJECTIVES

To assess the pulmonary function of patients with SJS/TEN after remission.

METHODS

Analysis of pulmonary function tests (PFTs) performed during the usual follow-up of patients with SJS/TEN managed in a referral centre from April 2007 to January 2010.

RESULTS

Of 58 patients admitted, 32 underwent PFTs (17 male, 15 female). The median time from the acute stage to PFTs was 3 months (interquartile range 1-18). Three patients had grade 2 dyspnoea. Eighteen patients (56%) had abnormal PFTs, including 13 patients (41%) with moderately altered diffusion capacity for carbon monoxide (DLCO ) normalized by the alveolar volume (VA) (giving the ratio KCO , which equals DLCO /VA) and five patients with decreased total lung capacity. No airway obstruction was observed. Patients with decreased KCO had higher initial detached body surface area than others (30% vs. 10%, P = 0·006), as did those with decreased DLCO (25% vs. 10%; P = 0·054). There were correlations between detached body surface area and both KCO (r = -0·41, P = 0·026) and DLCO (r = -0·47, P = 0·011). Among 10 patients with decreased KCO on the first PFT, eight patients had a sustained decrease in KCO on a second PFT.

CONCLUSIONS

More than half of patients with SJS/TEN displayed abnormalities on PFTs, mainly diffusion impairment, which was associated with higher initial skin surface detachment. These abnormalities were mostly asymptomatic and remained stable over time.

Serum concentrations of metalloproteinase 2, metalloproteinase 9 and granzyme B in contact eczema patients

Introduction

Contact eczema is a common skin condition with complex etiology, variable clinical presentation and lengthy therapy duration. The mechanism of contact eczema is complex, since it is affected by multiple inflammatory mediators.

Aim

To assess concentrations of metalloproteinase 2 (MMP-2), metalloproteinase 9 (MMP-9) and granzyme B (GzmB) in patients with contact eczema.

Material and methods

Seventy patients with contact eczema and 30 healthy persons as controls were included in the study. In all subjects, MMP-2, MMP-9 and GzmB were determined using ELISA immunoassay. In study group patients, concentrations were assayed in periods of disease exacerbation and remission. Obtained results were analyzed statistically.

Results

Mean MMP-2 and GzmB concentrations were found to be significantly higher in the study group than in the control group. Mean MMP-2, MMP-9 and GzmB levels were also statistically significantly higher during skin lesion relapse compared to contact eczema remission periods.

Conclusions

The presented paper demonstrates that MMP-2, MMP-9 and GzmB are good markers of contact eczema exacerbations.

Definitions and mechanisms of drug hypersensitivity

Adverse drug reactions are a difficult problem faced by clinicians in everyday practice. The mechanisms of drug hypersensitivity are not well understood. This is reflected by difficulties in their classification, which is mainly based upon the current knowledge of immunologic and nonimmunologic mechanisms, onset of symptoms (immediate or nonimmediate) and morphology. For the individual patient, the correct diagnosis and classification is important because strict avoidance of the offending drug might be of vital importance. Considerable experience is required to guide management, to interpret results of investigations and to undertake drug challenges. This article summarizes the current knowledge regarding definitions and mechanisms. However, the field of drug hypersensitivity is rapidly expanding. Modern drugs such as biological agents bare hypersensitivity risks that are potentially mediated by, so far, unknown mechanisms.

Death ligand TRAIL, secreted by CD1a+ and CD14+ cells in blister fluids, is involved in killing keratinocytes in toxic epidermal necrolysis

Toxic epidermal necrolysis (TEN) is characterized by an acute detachment and destruction of keratinocytes, affecting large areas of the skin. It is often related to adverse drug reactions. Previous studies have shown that effector CD8+ T cells, which accumulate in the blister fluid, are functionally cytotoxic and act through a classical perforin/granzyme B pathway. It has recently been shown that these cytotoxic T cells also secrete granulysin peptide, which is lethal to keratinocytes. These cytotoxic T cells exert their killer activity against autologous keratinocytes in the presence of the drug. However, they are unlikely to be the only effectors of TEN. We therefore searched for soluble death factors in the blister fluids that might kill keratinocytes. We found that the amounts of interferon-γ, TRAIL and TNF-α proteins were significantly greater in TEN blister fluids than in all controls (normal sera, TEN sera, burns and Eosinophilic pustular folliculitis blister fluids) and TNF-like weak inducer of apoptosis (TWEAK) amounts are also greater in all controls except burns. We showed that these proteins acted in synergy to induce the death of keratinocytes in vitro. We also found that TRAIL and TWEAK were secreted by CD1a+ and CD14+ cells present in the blister fluids. Thus, in addition to MHC class I-restricted cytotoxic T lymphocytes (CTLs), which lyse keratinocytes, ligands secreted by non-lymphoid cells capable of inducing keratinocyte death in an MHC class I-independent manner, also seem to be present in the blister fluids of patients with TEN.

Pharmacogenetics of drug hypersensitivity

Drug hypersensitivity reactions and severe cutaneous adverse drug reactions, such as Stevens-Johnson syndrome and toxic epidermal necrolysis, are examples of serious adverse drug reactions mediated through a combination of metabolic and immunological mechanisms that could traditionally not have been predicted based on the pharmacological characteristics of the drug alone. The discovery of new associations between these syndromes and specific HLA has created the promise that risk for these reactions could be predicted through pharmacogenetic screening, thereby avoiding serious morbidity and mortality associated with these types of drug reactions. Despite this, several hurdles exist in the translation of these associations into pharmacogenetic tests that could be routinely used in the clinical setting. HLA-B*5701 screening to prevent abacavir hypersensitivity syndrome is an example of a test now in widespread routine clinical use in the developed world.