Involvement of macrophages in the pathology of toxic epidermal necrolysis

T Cell Assessment in Allergic Drug Reactions during the Acute Phase According to the Time of Occurrence

Allergic drug reactions can be classified as immediate, accelerated or delayed. This classification usually correlates with the mechanism involved: immediate reactions are IgE mediated and delayed reactions are T cell dependent. We analyzed lymphocyte involvement in patients with these reactions by determining cell subpopulations, activation state and skin homing receptor expression (CLA) in blood and skin. Patients with immediate, accelerated and delayed reactions were evaluated during the acute phase and after resolution. Controls taking drugs were included. Phenotypic immunofluorescence analysis was done by flow cytometry in peripheral blood, and by immunohistochemistry in skin for delayed reactions. Forty-six patients were included, 17 with immediate reactions, 10 accelerated and 19 delayed. At the acute phase CLA was significantly increased in delayed reactions and HLA-DR in all three types of reaction. In the severest delayed reactions, Steven-Johnson/Lyell syndromes, the CD4 subsets were increased in peripheral blood and skin compared to maculopapular exanthemas and urticaria and HLA-DR when compared with urticaria. In maculopapular exanthemas CLA was significantly increased in peripheral blood and skin compared to urticaria and the severe reactions. We found that T-cells are implicated, besides delayed reactions, in immediate and accelerated reactions. In delayed reactions there is a parallelism between results found in skin and peripheral blood with a higher participation of CD4+ cells the more severe the reaction.

Immunological mechanisms of epidermal damage in toxic epidermal necrolysis

PURPOSE OF REVIEW

The purpose of the present review is to introduce recent findings on the pathomechanisms of toxic epidermal necrolysis (TEN), which is characterized by widespread epidermal detachment due to keratinocyte apoptosis.

RECENT FINDINGS

In the mechanism of epidermal damage, the roles of drug metabolites, cytotoxic lymphocytes, and apoptosis-inducing factors have been noted. In addition, recent studies have focused on monocytes/macrophages, which may participate in epidermal damage through the production of apoptosis-inducing factors and the expression of costimulatory factors with the ability to activate CD8 T cells.

SUMMARY

Epidermal keratinocyte death is a hallmark of TEN. In a very high proportion of cases, drugs are responsible for TEN. It has been suggested that toxic drug metabolites produced by keratinocytes act like electrophilic agents to induce apoptosis and inflammation. Next, cytotoxic lymphocytes and monocytes function in the development of widespread epidermal damage through direct or indirect cytotoxic pathways. In addition, T-cell activation may be strengthened by the impairment of regulatory T-cell function and activated monocytes. The development of epidermal damage in TEN may require the coordinated action of these factors.

Possible involvement of CD14+ CD16+ monocyte lineage cells in the epidermal damage of Stevens-Johnson syndrome and toxic epidermal necrolysis

BACKGROUND

Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are characterized by keratinocyte apoptosis and necrosis, resulting in epidermal detachment. Although monocytes abundantly infiltrate the epidermis in SJS/TEN skin lesions, the properties and functions of these cells have not been fully examined.

OBJECTIVES

To determine the properties of monocytes infiltrating into the epidermis in SJS/TEN.

METHODS

Immunostaining of skin sections was performed to examine the membrane markers of monocytes infiltrating into skin lesions.

RESULTS

Immunostaining of cryosections from 11 SJS/TEN skin lesions revealed numerous CD14+ monocytes located along the dermoepidermal junction and throughout the epidermis. The cells coexpressed CD16, CD11c and HLA-DR. CD14+ CD16+ cells were identified in very early lesions without epidermal damage, suggesting that their infiltration is a cause, rather than a result, of epidermal damage. Moreover, these cells expressed CD80, CD86 and CD137 ligand, indicative of their ability to facilitate the proliferation and cytotoxicity of CD8+ T cells. CD16+ cells infiltrating the epidermis and detected at the dermoepidermal junction were immunostained and counted in paraffin-embedded skin sections obtained from 47 patients with drug rash manifested as TEN, SJS, maculopapular-type rash or erythema multiform-type rash. The number of CD16+ monocytes infiltrating the epidermis increased significantly, depending on the grade of epidermal damage.

CONCLUSIONS

These findings suggest that the appearance of CD14+ CD16+ cells of monocyte lineage plays an important role in the epidermal damage associated with SJS/TEN, most probably by enhancing the cytotoxicity of CD8+ T cells.

New insights in toxic epidermal necrolysis (Lyell's syndrome): clinical considerations, pathobiology and targeted treatments revisited

Drug-induced toxic epidermal necrolysis (TEN), also known as Lyell's syndrome, is a life-threatening drug reaction characterized by extensive destruction of the epidermis and mucosal epithelia. The eyes are typically involved in TEN. At present, the disease has a high mortality rate. Conceptually, TEN and the Stevens-Johnson syndrome are closely related, although their severity and outcome are different. Distinguishing TEN from severe forms of erythema multiforme relies on consideration of aetiological, clinical and histological characteristics. The current understanding of the pathomechanism of TEN suggests that keratinocytes are key initiator cells. It is probable that the combined deleterious effects on keratinocytes of both the cytokine tumour necrosis factor (TNF)-alpha and oxidative stress induce a combination of apoptotic and necrotic events. As yet, there is no evidence indicating the superiority of monotherapy with corticosteroids, ciclosporin (cyclosporine) or intravenous immunoglobulins over supportive care only for patients with TEN. However, the current theory of TEN pathogenesis supports the administration of a combination of antiapoptotic/antinecrotic drugs (e.g. anti-TNF-alpha antibodies plus N-acetylcysteine) targeting different levels of the keratinocyte failure machinery.

Early pathological features of the cornea in toxic epidermal necrolysis

AIM

To describe the early pathological changes in the cornea during toxic epidermal necrolysis (TEN).

METHOD

Demonstration of histological features of sequential corneal samples taken during management of complications of TEN in a young adult.

RESULTS

Early vacuolation of basal keratinocytes and late infiltration of the cornea with CD 8 lymphocytes were observed. These changes are similar to those found in cutaneous TEN and may represent weakening of the stromal-epithelium interface with resultant recurrent erosion and chronic inflammation.

CONCLUSIONS

Similar changes were found in avascular corneal tissue to those previously described in skin. The initial insult may be traumatic. We propose that a cytokine-mediated response contributes to the initial insult, either in response to and/or by accelerating severe inflammation. This precedes a cytotoxic infiltration which may exacerbate episodes of recurrent erosion. This provides a new insight into the mechanism of disease in the cornea following TEN.

Stevens-Johnson syndrome and toxic epidermal necrolysis: a review of the literature

OBJECTIVE

To perform a comprehensive review of Stevens-Johnson syndrome and toxic epidermal necrolysis.

DATA SOURCES

A MEDLINE search was performed for the years 1975 to 2003 using the keywords Stevens-Johnson syndrome and toxic epidermal necrolysis to identify relevant articles published in English in peer-reviewed journals.

STUDY SELECTION

All clinical studies that reported on 4 or more patients, review articles, and experimental studies that concerned disease mechanisms were selected and further analyzed. Clinical reports that included fewer than 4 patients were selected only if they were believed to carry a significant message about disease mechanism or therapy.

RESULTS

Stevens-Johnson syndrome and toxic epidermal necrolysis seem to be variants of the same disease with differing severities. A widely accepted consensus regarding diagnostic criteria and therapy does not exist at present. Despite the recent experimental studies, the pathogenic mechanisms of these diseases remain unknown. Although progress in survival through early hospitalization in specialized burn units has been made, the prevalence of life-long disability from the ocular morbidity of Stevens-Johnson syndrome and toxic epidermal necrolysis has remained unchanged for the past 35 years. Further progress depends on modification of the acute phase of the disease rather than continuation of supportive care. The available published evidence indicates that a principal problem in the pathogenesis is immunologic and that immunomodulatory intervention with short-term, high-dose intravenous steroids or intravenous immunoglobulin holds the most promise for effective change in survival and long-term morbidity.

CONCLUSIONS

The results of this review call for a widely accepted consensus on diagnostic criteria for Stevens-Johnson and toxic epidermal necrolysis and multicenter collaboration in experimental studies and clinical trials that investigate disease mechanisms and novel therapeutic interventions, respectively.

Characterization of a potential animal model of an idiosyncratic drug reaction: nevirapine-induced skin rash in the rat

Idiosyncratic drug reactions are difficult to study in humans due to their unpredictability. Unfortunately, this characteristic also hinders the development of animal models needed for mechanistic studies. Nevirapine, used to treat human immunodeficiency virus (HIV) infections, results in a severe idiosyncratic skin rash in some patients. We found that nevirapine can also cause a significant rash in some strains of rats. At a dose of 150 mg/kg/day, the incidence in female Sprague-Dawley rats was 6/28 (21%), in female Brown Norway rats 32/32 (100%), and in female Lewis rats 0/6 (0%) while no male Sprague-Dawley or Brown Norway rats developed a rash. Female SJL mice 0/7 also did not develop nevirapine-induced skin lesions. The first sign of a reaction in Brown Norway rats was red ears at days 7-10 followed by a rash with scabbing mainly on the back; this was a shorter time to onset than in Sprague-Dawley rats. Light microscopy of the skin revealed a primarily mononuclear inflammatory infiltrate and lesions typical of self-trauma. Immunohistochemistry results suggest that the infiltrate was composed of CD4 and CD8 T cells as well as macrophages. A lower dose of either 40 or 75 mg/kg/day did not lead to a rash and, in fact, 2 weeks of the lower doses induced tolerance to the 150 mg/kg/day dose in female Brown Norway rats. A dose of 100 mg/kg/day resulted in rash in 2/4 (50%) of female Brown Norway rats. Rechallenge of Brown Norway rats that had been allowed to recuperate after a nevirapine-induced rash led to red ears in less than 24 h followed by hair loss and occasional skin lesions. Although the skin rash was less evident on rechallenge, microscopically, the cellular infiltrate was more prominent, especially surrounding the hair follicles. Moreover, there were lesions of interface dermatitis with apoptosis and satellitosis, indicative of a cell-mediated immune attack on the epidermis. While systemic signs of illness did not accompany the rash on primary exposure, on rechallenge, the animals appeared generally unwell and this forced sacrifice after 2 weeks or less of treatment. Importantly, splenocytes isolated from rechallenged animals were able to transfer susceptibility to nevirapine-induced skin rash to naïve female Brown Norway recipients, which was illustrated by a faster time to onset of rash in the recipients. The characteristics of this adverse reaction are similar to that seen in humans; that is, it is idiosyncratic in that it only occurs in some strains of animals, is delayed in onset, is more common in females, is dose-dependent, and appears to be immune-mediated. Therefore, it may represent a good animal model for the study of idiosyncratic drug reactions.

Mechanisms in cutaneous drug hypersensitivity reactions

Up to 3% of all hospital admissions are due to adverse drug reactions (ADRs), and between 10% and 20% of hospital inpatients develop ADRs. Individual susceptibility to becoming 'sensitized' or allergic to a drug is thought to result from altered metabolic handling of the drug. Reactive intermediate compounds form haptens, bind to proteins and induce immune responses. Depending on whether the immune system generates antibodies or sensitized T cells, different clinical patterns of hypersensitivity may result. At present, both in vivo or in vitro tests to identify the culprit drug or to confirm the presence of hypersensitivity are not widely used because they are either not generally robust or not readily accessible. In vitro tests require the true immunogen/antigen to detect antibodies or sensitized T cells. As the metabolic basis underlying susceptibility to adverse drug reactions is elucidated, the resolution of immunological mechanisms and development of reliable tests will ensue. This will also become of great value for prediction of individuals at risk of becoming sensitized by a particular drug.

Toxic epidermal necrolysis in children--an update

Toxic epidermal necrolysis (TEN) is a relatively rare disease, characterized by generalized erythema, bulla formation, and exfoliation of the epidermis that resembles scalding. It is usually drug-induced and mediated by immune reactions of several types. TEN has to be differentiated from erythema multiforme and Stevens-Johnson syndrome. TEN bears a life-threatening potential and a risk for significant complications such as dehydration; secondary infections; pulmonary, gastrointestinal, and renal involvement; and late scarring with cosmetic and functional implications. Therapeutic interventions include admission in a burn center unit, systemic antibiotics and corticosteroids, topical therapy with antibacterial agents and biological dressings, and supportive measures.

Anticonvulsant-induced toxic epidermal necrolysis: monitoring the immunologic response

BACKGROUND

Toxic epidermal necrolysis is a severe reaction with skin involvement induced by different drugs and other agents. The mechanisms implicated in the induction of the reaction are poorly understood.

OBJECTIVE

Our purpose was to study the involvement of T lymphocytes and other immunocompetent cells in the peripheral blood, blister fluid, and affected skin of 3 patients who had a severe reaction after receiving anticonvulsant medication.

METHODS

Quantification of T lymphocytes expressing the skin-homing receptor (cutaneous lymphocyte-associated antigen ¿CLA) in peripheral blood, skin, and skin blister fluid and assessment of other adhesion molecules, activation markers, and inflammatory interleukins by flow cytometry, immunohistochemistry, and reverse transcription-PCR.

RESULTS

An increase in CD3(+)CLA(+) cells paralleling the severity of the disease was observed in both peripheral blood and skin, tending to normalize as soon as patient's conditions improved. E-selectin was detected in endothelial vessels in parallel with CLA expression on lymphocytes. An overexpression of TNFalpha, IFN-gamma, and IL-2 was also observed in PBMCs. The expression of the different markers changed over the course of the disease.

CONCLUSIONS

These data show an increase in activated T cells expressing the skin-homing receptor in both tissue and peripheral blood accompanying clinical symptoms, with a recruitment of macrophages and an overexpression of cytokines. All these results suggest an important role for T cells in the production of toxic epidermal necrolysis.

Pulmonary complications in toxic epidermal necrolysis: a prospective clinical study

OBJECTIVE

To evaluate the incidence, clinical features, and prognosis of pulmonary complications associated with toxic epidermal necrolysis

DESIGN

Prospective study.

SETTING

Dermatology intensive care unit in Mondor Hospital, France.

PATIENTS

41 consecutive patients.

INTERVENTIONS

On admission, then daily, respiratory evaluation was based on clinical examination, chest X-ray, and arterial blood gas analysis. When clinical symptoms, X-ray abnormalities, or hypoxemia [partial pressure of oxygen (PO2) < 80 mm Hg] were present, fiberoptic bronchoscopy was performed.

RESULTS

10 patients presented early manifestations: dyspnea (n = 10), bronchial hypersecretion (n = 7), marked hypoxemia (n = 10) (PO2 = 59 +/- 8 mm Hg). Chest X-ray was normal (n = 8) or showed interstitial infiltrates (n = 2). In these 10 patients, fiberoptic bronchoscopy demonstrated sloughing of bronchial epithelium in proximal airways. Delayed pulmonary complications occurred in 6 of these 10 patients from day 7 to day 15: pulmonary edema (n = 2), atelectasis (n = 1), bacterial pneumonitis (n = 4). Mechanical ventilation was required in 9 patients. A fatal outcome occurred in 7 patients. Seven patients did not develop early pulmonary manifestations (PO2 on admission 87 +/- 6 mm Hg) but only delayed pulmonary symptoms related to atelectasis (n = 1), pulmonary edema (n = 4), and bacterial pneumonitis (n = 3); bronchial epithelial detachment was not observed. None of them required mechanical ventilation and all recovered with appropriate therapy.

CONCLUSIONS

"Specific" involvement of bronchial epithelium was noted in 27% of cases and must be suspected when dyspnea, bronchial hypersecretion, normal chest X-ray, and marked hypoxemia are present during the early stages of toxic epidermal necrosis. Bronchial injury seems to indicate a poor prognosis, as mechanical ventilation was required for most of these patients and was associated with a high mortality.

Toxic epidermal necrolysis

Toxic epidermal necrolysis (TEN) is a rare, drug-induced, life-threatening syndrome with widespread epidermal loss and mucosal erosions. The classification, pathophysiology, clinical features and treatment are discussed in this review. Prognosis has improved as admission to a burns unit and early treatment of infection has become standard management. The role of corticosteroids in treatment is still controversial.

Stimulatory effects of FK156 in a panel of tests designed to detect changes in immune function

There is a need to evaluate the utility of experimental models in immune function assessment if these are to be accepted in preclinical safety studies. We have evaluated a panel of tests measuring cellularity and functions of the lymphoid system in the Fischer rat in order to determine whether they would detect immunostimulation, rather than suppression. Injection of the peptide immunostimulant FK156 (D-lactyl-L-alanyl-y-D-glutamyl-(L)-meso-diaminopimelyl- (L)-glycine) increased the numbers of macrophages recovered from the peritoneal cavity, and stimulated their activity, as measured by chemiluminescence, adherence, and secretion of interleukin 1. In vitro, T lymphocytes had an increased background incorporation of tritiated thymidine, increased response to sub-optimal concentrations of concanavalin A, and an increase in secretion of interleukin 2 at optimal concentrations of concanavalin A. There was no change in the proliferative responses of B lymphocytes in vitro. Antibody responses to tetanus toxoid in vivo were increased. These changes were not reflected in consistent, statistically significant alterations in the numbers of lymphocytes bearing either lineage markers or the interleukin 2 receptor as a marker of activation.

Toxic epidermal necrolysis (Lyell syndrome)

Toxic epidermal necrolysis is perhaps the most formidable disease encountered by dermatologists. Uncommon but not rare, toxic epidermal necrolysis occurs in 60 to 70 persons per year in France. It remains as puzzling a disorder as it was 34 years ago, when described by Lyell. Whether or not toxic epidermal necrolysis is the most severe form of erythema multiforme is still the subject of discussion. The physiopathologic events that lead to this rapidly extensive necrosis of the epidermis are not understood. Indirect evidence suggests a hypersensitivity reaction, but the search for potential immunologic mechanisms has resulted in little data to support this hypothesis. Accumulated clinical evidence points to drugs as the most important, if not the only, cause of toxic epidermal necrolysis. Sulfonamides, especially long-acting forms, anticonvulsants, nonsteroidal anti-inflammatory agents, and certain antibiotics are associated with most cases of toxic epidermal necrolysis. Many other drugs have been implicated in isolated case reports. All organs may be involved either by the same process of destruction of the epithelium as observed in the epidermis or by the same systemic consequences of "acute skin failure" as seen in patients with widespread burns. Sepsis is the most important complication and cause of death. Approximately 20% to 30% of all patients with toxic epidermal necrolysis die. Elderly patients and patients with extensive lesions have a higher mortality rate. Surviving patients completely heal in 3 to 4 weeks, but up to 50% will have residual, potentially disabling ocular lesions. The prognosis is improved by adequate therapy, as provided in burn units, that is, aggressive fluid replacement, nutritional support, and a coherent antibacterial policy. Corticosteroids, advocated by some in high doses to halt the "hypersensitivity" process, have been shown in several studies to be detrimental and should be avoided.

Clinical, histological, and immunohistological studies of postoperative erythroderma

We report 7 cases of acute fatal illness characterized by fever, diffuse erythematous rash, and progressive leukopenia occurring 10 days after surgical operation. The outcome was uniformly fatal. The biopsy findings consisted of eosinophilic individual necrosis of epidermal cells, satellite cell necrosis, basal liquefaction degeneration, and scanty cell infiltration into the dermis. T lymphocytes were found in the epidermis but Langerhans cells disappeared. These findings are compatible with acute graft-vs-host disease following blood transfusion. Explanations based upon drug allergy, infection, toxic shock syndrome, or toxic epidermal necrolysis seem less reasonable.