Toxic epidermal necrolysis: a paradigm of critical illness

<p></p><p>ABSTRACT Toxic epidermal necrolysis is an adverse immunological skin reaction secondary in most cases to the administration of a drug. Toxic epidermal necrolysis, Stevens-Johnson syndrome, and multiform exudative erythema are part of the same disease spectrum. The mortality rate from toxic epidermal necrolysis is approximately 30%. The pathophysiology of toxic epidermal necrolysis is similar in many respects to that of superficial skin burns. Mucosal involvement of the ocular and genital epithelium is associated with serious sequelae if the condition is not treated early. It is generally accepted that patients with toxic epidermal necrolysis are better treated in burn units, which are experienced in the management of patients with extensive skin loss. Treatment includes support, elimination, and coverage with biosynthetic derivatives of the skin in affected areas, treatment of mucosal involvement, and specific immunosuppressive treatment. Of the treatments tested, only immunoglobulin G and cyclosporin A are currently used in most centers, even though there is no solid evidence to recommend any specific treatment. The particular aspects of the treatment of this disease include the prevention of sequelae related to the formation of synechiae, eye care to prevent serious sequelae that can lead to blindness, and specific immunosuppressive treatment. Better knowledge of the management principles of toxic epidermal necrolysis will lead to better disease management, higher survival rates, and lower prevalence of sequelae.</p><p></p

Summary of mutations found in the <i>ARID1A</i> resequencing study.

<p>Non-synonymous mutations found at a frequency ≥10% that were confirmed by Sanger sequencing are shown here.</p>*<p>denotes a truncating mutation.</p

<i>ARID1A</i> mutations and expression in UBC.

<p><i>Panel A</i>. A G>C transversion identified through Solexa resequencing, confirmed by Sanger sequencing of independent PCR products, leading to a predicted Q2210H substitution in VMCUB-3 cells. <i>Panel B</i>. Western blotting analysis in a panel of UBC cell lines identifies a subset with undetectable expression, including VMCUB-3. mRNA expression was analyzed by RT-qPCR; results are shown as values normalized with respect to the housekeeping gene <i>HPRT</i>. <i>Panel C</i>. A C>T mutation in codon 403, leading to a premature stop codon, was identified in a primary T1G3 tumor. The mutation was absent from matched normal leukocyte DNA. Lack of protein expression in the corresponding tumor tissue was confirmed using immunohistochemistry. The red arrowhead points to a tumor cell lacking ARID1A staining, whereas the black arrowhead indicates a positive stromal cell. For comparison, a TaG1 tumor with wild type <i>ARID1A</i> sequence is shown.</p

Loss of ARID1A expression is associated with more aggressive UBC and with patient outcome.

<p>ARID1A expression was assessed by IHC on tissue microarrays. Patients (n = 84) were followed-up as indicated in Methods and classified as having “recurred”, “progressed”, or being free of disease. Patients with high ARID1A-expresssing tumors display a lower risk of recurrence and a higher risk of progression indicating a more aggressive clinical course.</p

Loss of ARID1A expression is associated with more aggressive UBC.

<p>UBC cases were classified in three categories: low grade NMI (TaG1 and TaG2 tumors), high grade NMI (TaG3 and T1G3 tumors), and MI (≥T2 tumors). <i>Panel A</i>. ARID1A immunohistochemical score is significantly lower in more aggressive, advanced tumors. FGFR3 immunohistochemical score, which is directly associated with <i>FGFR3</i> mutations, is also significantly lower in more aggressive tumors. By contrast, p53 score is higher in more aggressive tumors. <i>Panel B</i>. Differential expression of <i>ARID1A, FGFR3</i> and <i>TP53</i> at the mRNA level is observed in two different, independent UBC microarray series: the mRNA levels of all 3 genes are significantly lower in MIBC. *denotes an FDR adjusted <i>P</i>-value <0.5.</p

Characteristics of the patients and tumors included in series 2 (tissue microarray).

<p>Characteristics of the patients and tumors included in series 2 (tissue microarray).</p

Characteristics of the patients from whom fresh tumor was used for <i>ARID1A</i> sequence analysis.

<p>Characteristics of the patients from whom fresh tumor was used for <i>ARID1A</i> sequence analysis.</p

Relationship between ARID1A and cell differentiation markers, as detected using immunohistochemistry in tumor tissue microarrays.

<p>UBC cases were classified in three categories: LG-NMIBC (TaG1 and TaG2 tumors), HG-NMIBC (TaG3 and T1G3 tumors), and MI (≥T2 tumors). Non-hierarchical clustering of IHC scores for ARID1A, FGFR3, KRT5/6, KRT14, and KRT20 was performed. IHC scores are shown in a green-red color code. Color bars below the dendogram include information about tumor stage and grade (tones of blue) and <i>FGFR3</i> mutational status (grey/black) when known. White squares indicate that information for that parameter is not available.</p

Effects of <i>ARID1A</i> knockdown in UBC cell lines.

<p><i>Panel A</i>. <i>ARID1A</i> was knocked-down using three different shRNAs in the RT112 and VMCUB-3 cells. The knock-down was efficient at both the protein and mRNA levels. The bars represent the relative quantification of ARID1A mRNA levels taking non-targeting shRNA interfered cells as controls. <i>Panel B</i>. The quantification colony formation is shown, with error intervals of results from triplicate experiments denoting SEM. In RT112 cells, ARID1A knockdown was associated with reduced colony formation. By contrast, no major effects were observed in VMCUB-3 cells harboring an <i>ARID1A</i> mutation. Representative morphological changes in cells interfered with control shNT (scrambled shRNA) and with one of the shRNAs targeting <i>ARID1A</i> are shown.</p