Biagio Didona

Pemphigus autoantibodies generated through somatic mutations target the desmoglein-3 cis-interface

Pemphigus vulgaris (PV) is an autoimmune blistering disease of skin and mucous membranes caused by autoantibodies to the desmoglein (DSG) family proteins DSG3 and DSG1, leading to loss of keratinocyte cell adhesion. To learn more about pathogenic PV autoantibodies, we isolated 15 IgG antibodies specific for DSG3 from 2 PV patients. Three antibodies disrupted keratinocyte monolayers in vitro, and 2 were pathogenic in a passive transfer model in neonatal mice. The epitopes recognized by the pathogenic antibodies were mapped to the DSG3 extracellular 1 (EC1) and EC2 subdomains, regions involved in cis-adhesive interactions. Using a site-specific serological assay, we found that the cis-adhesive interface on EC1 recognized by the pathogenic antibody PVA224 is the primary target of the autoantibodies present in the serum of PV patients. The autoantibodies isolated used different heavy- and light-chain variable region genes and carried high levels of somatic mutations in complementary-determining regions, consistent with antigenic selection. Remarkably, binding to DSG3 was lost when somatic mutations were reverted to the germline sequence. These findings identify the cis-adhesive interface of DSG3 as the immunodominant region targeted by pathogenic antibodies in PV and indicate that autoreactivity relies on somatic mutations generated in the response to an antigen unrelated to DSG3.

Etanercept therapy for toxic epidermal necrolysis

BACKGROUND Toxic epidermal necrolysis (TEN) is a severe and potentially lethal drug reaction for which no standard treatment is available. OBJECTIVE To describe a case series of patients with TEN treated with a single dose of etanercept. METHODS We observed 10 consecutive patients with TEN. For each patient, we recorded the presence of comorbidities and all the drugs recently started (ie, in the last month). In all cases, 50 mg of etanercept was administered in a single subcutaneous injection. The clinical severity of disease was computed using the SCORe of Toxic Epidermal Necrosis (SCORTEN) scale. Using the probabilities of death linked to each level of SCORTEN score, we calculated the expected probability of death in our patients. Healing was defined as complete reepithelialization, and a time to healing curve was then obtained using the Kaplan-Meier method. RESULTS All patients promptly responded to treatment, reaching complete reepithelialization without complications or side effects. The median time to healing was 8.5 days. LIMITATIONS This is a small, uncontrolled case series. CONCLUSION These preliminary results suggest the possibility that tumor necrosis factor-alfa may be an effective target for control of TEN, a dangerous skin condition for which no effective cure has yet been found.

UV mutation signature in tumor suppressor genes involved in skin carcinogenesis in xeroderma pigmentosum patients

Molecular analysis of p53 and patched (PTCH), two candidate tumor suppressor genes for non-melanocytic skin cancer, was performed in skin tumors from six patients affected by the cancer-prone disease xeroderma pigmentosum (XP). UV-specific p53 mutations were detected at a frequency of 38–50% in all the tumor types analysed, including melanomas. Additional analysis of PTCH mutations in the subset of eight basal call carcinomas (BCC) revealed a very high mutation frequency of this gene (90%) which exceeded that detected in the p53 gene in the same tumors (38%). PTCH mutations were predominantly UV-specific C>T transitions. This mutation pattern is different from that reported in BCC from normal donors where PTCH mutation frequency is 27% and mutations are frequently deletions and insertions. These findings suggest that PTCH mutations represent an earlier event in BCC development than p53 alterations and that the inability of XP patients to repair UV-induced PTCH mutations might significantly contribute to the early and frequent appearance of BCC observed in these patients.

Toxic epidermal necrolysis successfully treated with etanercept.

Toxic epidermal necrolysis (TEN) is a rare and acute severe adverse reaction to drugs, characterised by massive apoptosis and widespread epidermal and mucosal detachment. Although no gold standard therapy exists, human i.v. immunoglobulins have recently been described as an effective treatment for this disease. We report a case of phenobarbital‐induced TEN in a 59‐year‐old white woman where the epidermal detachment stopped 48 h after beginning the etanercept treatment with complete healing after 20 days. To the best of our knowledge, this is only the second reported case of TEN successfully treated with etanercept.

Markedly reduced incidence of melanoma and nonmelanoma skin cancer in a nonconcurrent cohort of 10,040 patients with vitiligo

BACKGROUND Genetic findings suggesting a lower susceptibility to melanoma in patients with vitiligo are supported by recent clinical studies. Nonmelanoma skin cancer (NMSC) has also been studied, but mainly in small samples, and with conflicting results. OBJECTIVE We sought to study the relative risk (RR) of melanoma and NMSC in patients with vitiligo compared with that in patients seen for vascular surgery. METHODS The frequency of melanoma and NMSC was compared between patients with vitiligo and patients seen for vascular surgery. Occurrence of skin cancer was compared by computing RR and modeled using multiple logistic regression. RESULTS Overall, the crude RR for melanoma was 0.24 (95% confidence interval [CI] 0.13-0.45) in patients with vitiligo compared with those with a nondermatologic condition (occurrence 1.1‰, 95% CI 0.5‰-2.0‰ in patients with vitiligo and occurrence 4.5‰, 95% CI 3.8‰-5.4‰ in the control cohort). The crude RR for NMSC was 0.19 (95% CI 0.14-0.17) and the occurrence was 3.8‰ (95% CI 2.7‰-5.2‰) among patients with vitiligo and 19.6‰ (95% CI 18.0‰-21.4‰) in control subjects. Patients with vitiligo who underwent phototherapy had a markedly higher risk of both cancers. CONCLUSIONS In our large study, patients with vitiligo have a decreased risk of developing skin neoplasms, even considering that a larger proportion in this patient group is exposed to higher levels of ultraviolet radiation.

An SRY‐negative XX male with Huriez syndrome

This report studies a 42‐year‐old 46,XX patient affected by palmoplantar keratoderma, clinically classified as Huriez syndrome. The patient showed a male phenotype with apparently normal male features including testicular development. Cytogenetic and chromosomal painting analysis excluded the presence of translocation of the Y chromosome. PCR analysis of genomic DNA failed to detect the presence of the testis‐determining gene, SRY. The presence of other Y‐chromosome genes, known to be involved in testicular maturation and spermatogenesis, has also been analyzed. The data suggest that the sex reversal in this 46,XX male patient is due to a defect on a yet unidentified autosomal or X‐linked sex‐determining gene. The relationship between the sex reversion and the presence of sclerotylosis is discussed.

Vitiligo: Pathogenesis, clinical variants and treatment approaches ☆

Vitiligo is a common chronic acquired disease of pigmentation whose etiology is unknown, which usually occurs with asymptomatic whitish patch or macule. Although several hypotheses have been proposed in the literature, the leading theory is still the auto-immune etiology linked to specific genetic mutations. Vitiligo can also be associated with several autoimmune diseases, including autoimmune thyroid diseases, alopecia areata, and halo nevi. Sensorineural hearing loss was reported in several vitiligo patients due to a reduction in the number of melanocytes contained in the membranous labyrinth of the inner ear. Because of its complexity, several therapeutic options are available to treat this systemic disease.

Treatment of refractory adult-onset pityriasis rubra pilaris with TNF-alpha antagonists: A case series

Background  Pityriasis rubra pilaris (PRP) is a rare inflammatory dermatosis with frequent clinical presentation as erythroderma. Conventional systemic treatment is often unsatisfactory and limited by long‐term toxicity. The use of tumour necrosis factor (TNF) antagonists has been reported previously in single cases, but lacking long‐term follow‐up or comparison between different biological agents.

Connexin 26 (GJB2) mutations, causing KID Syndrome, are associated with cell death due to calcium gating deregulation.

The autosomic dominant KID Syndrome (MIM 148210), due to mutations in GJB2 (connexin 26, Cx26), is an ectodermal dysplasia with erythematous scaly skin lesions, keratitis and severe bilateral sensorineural deafness. The Cx26 protein is a component of gap junction channels in epithelia, including the cochlea, which coordinates the exchange of molecules and ions. Here, we demonstrate that different Cx26 mutants (Cx26D50N and Cx26G11E) cause cell death in vitro by the alteration of intra-cellular calcium concentrations. These results help to explain the pathogenesis of both the hearing and skin phenotypes, since calcium is also a potent regulator of the epidermal differentiation process.

Quality of life in patients with pemphigus receiving adjuvant therapy

Background.  Pemphigus has a strong effect on patients’ quality of life (QOL).