Characterization of EDARADD gene mutations responsible for hypohidrotic ectodermal dysplasia.

Hypohidrotic ectodermal dysplasia (HED) is a genetic disorder characterized by hypohidrosis, hypodontia, and hypotrichosis. Autosomal forms of the disease are caused by mutations in either EDAR or EDARADD. To date, the underlying pathomechanisms for HED resulting from EDARADD mutations have not fully been disclosed. In this study, we performed detailed in vitro analyses in order to characterize three dominantly inherited missense mutations, p.D120Y, p.L122R, and p.D123N, and one recessively inherited missense mutation, p.E152K, in the EDARADD gene. Nuclear factor (NF)-κB reporter assays demonstrated that all the mutant EDARADD showed reduction in activation of NF-κB. Importantly, p.D120Y-, p.L122R-, and p.D123N-mutant EDARADD slightly reduced the NF-κB activity induced by wild-type EDARADD in a dominant negative manner. Co-immunoprecipitation assays showed that all of the mutant EDARADD were capable of binding to EDAR and wild-type EDARADD. Additional co-immunoprecipitation assays revealed that p.D120Y-, p.L122R-, and p.D123N-mutant EDARADD markedly prevented the interaction between EDAR and wild-type EDARADD, which further indicated a dominant negative effect by these mutations. Finally, we found that p.D120Y-, p.L122R-, and p.D123N-mutant EDARADD completely lost the ability to bind with TRAF6, while p.E152K-mutant EDARADD showed a mild reduction in the affinity. Our findings will provide crucial information toward unraveling the molecular mechanisms how EDARADD gene mutations cause the disease.

A novel mutation in early-onset sarcoidosis/Blau syndrome: an association with Propionibacterium acnes.

BACKGROUND: Early-onset sarcoidosis (EOS) and Blau syndrome (BS) are systemic inflammatory granulomatous diseases without visible pulmonary involvement, and are distinguishable from their sporadic and familial forms. The diseases are characterized by a triad of skin rashes, symmetrical polyarthritis, and recurrent uveitis. The most common morbidity is ocular involvement, which is usually refractory to conventional treatment. A gain-of-function mutation in the nucleotide-binding oligomerization domain-containing protein 2 (NOD2) gene has been demonstrated in this disease; however, little is known about the relationship between the activation of NOD2 and the pathophysiology of EOS/BS. Here we describe EOS/BS with a novel mutation in the NOD2 gene, as well as detection of Propionibacterium acnes (P. acnes) in the granulomatous inflammation. CASE PRESENTATION: An 8-year-old Japanese girl presented with refractory bilateral granulomatous panuveitis. Although no joint involvement was evident, she exhibited skin lesions on her legs; a skin biopsy revealed granulomatous dermatitis, and P. acnes was detected within the sarcoid granulomas by immunohistochemistry with P. acnes-specific monoclonal (PAB) antibody. Genetic analyses revealed that the patient had a NOD2 heterozygous D512V mutation that was novel and not present in either of her parents. The mutant NOD2 showed a similar activation pattern to EOS/BS, thus confirming her diagnosis. After starting oral prednisolone treatment, she experienced an anterior vitreous opacity relapse despite gradual prednisolone tapering; oral methotrexate was subsequently administered, and the patient responded positively. CONCLUSIONS: We presented a case of EOS/BS with a novel D512V mutation in the NOD2 gene. In refractory granulomatous panuveitis cases without any joint involvement, EOS/BS should be considered as a differential diagnosis; genetic analyses would lead to a definite diagnosis. Moreover, this is the first report of P. acnes demonstrated in granulomas of EOS/BS. Since intracellular P. acnes activates nuclear factor-kappa B in a NOD2-dependent manner, we hypothesized that the mechanism of granuloma formation in EOS/BS may be the result of NOD2 activity in the presence of the ligand muramyl dipeptide, which is a component of P. acnes. These results indicate that recognition of P. acnes through mutant NOD2 is the etiology in this patient with EOS/BS.

Purpuric drug eruption without leukocytoclastic vasculitis associated with vancomycin.

Vancomycin (VCM) has been reported to elicit adverse cutaneous drug reactions. However, VCM-associated purpuric drug eruption has not been reported yet, except leukocytoclastic vasculitis. A 16-year-old Japanese girl was admitted with a respiratory infection. We initiated intravenous administration of VCM. After the start of treatment, impalpable purpuric eruption appeared on her trunk. The eruption gradually extended to her neck, legs, and arms. Skin biopsy showed vasculitis with lymphocyte infiltration in the superficial dermis. A drug lymphocyte stimulation test yielded positive results for VCM. Her cutaneous symptoms rapidly reversed after the withdrawal of VCM. To the best of our knowledge, this is the first reported case of VCM-associated purpuric drug eruption, which differs from leukocytoclastic vasculitis. We recommend that VCM-associated purpuric drug eruption should be considered in the differential diagnosis during the administration of VCM, and a drug lymphocyte stimulation test may be useful for assessment of pathogenesis.

Functional studies for a dominant mutation in the EDAR gene responsible for hypohidrotic ectodermal dysplasia.

Hypohidrotic ectodermal dysplasia (HED) is a rare genetic disorder characterized by hypotrichosis, hypohidrosis and hypodontia. The disease shows X-linked recessive, autosomal dominant or autosomal recessive inheritance traits. The X-linked form of HED is caused by mutations in the EDA gene, while autosomal forms result from mutations in either EDAR or EDARADD genes. Regarding recessive mutations in the EDAR gene, the pathomechanisms have been well characterized. However, it has remained largely unknown how dominant mutations in the EDAR cause HED. In this study, we performed in vitro analyses for a dominant EDAR gene mutation, p.F398*, as a representative. We showed that the p.F398* mutant EDAR completely lost its affinity to EDARADD, and suppressed the downstream nuclear factor-κB activation induced by wild-type EDAR in a dominant-negative manner. Furthermore, we demonstrated that the mutant EDAR was capable of binding with the wild-type EDAR, which led to reduced interaction between the wild-type EDAR and EDARADD. Our findings not only underscore an essential role of the interaction between EDAR and EDARADD in ectodermal development, but also disclose, in part, the molecular basis of autosomal dominant HED.

The free radical scavenger edaravone suppresses experimental closed duodenal loop-induced acute pancreatitis in rats.

Recent studies suggest that the enhanced release of reactive oxygen species (ROS) plays an important role in the pathogenesis of clinical acute pancreatitis. In the present study, we investigated the effects of the free radical scavenger edaravone, which is used clinically as an anti-stroke agent, in the development of experimental closed duodenal loop (CDL)-induced acute pancreatitis. In the CDL-pancreatitis model, after edaravone and vehicle saline were injected intravenously, pancreatitis was induced for 7 h by the CDL technique. The subsequent ascites volume, wet pancreatic weight, serum amylase levels, and pancreatic tissue lipid peroxide levels were evaluated. Pancreatic tissue damage was also evaluated histologically. In this CDL-induced pancreatitis model, edaravone treatment tended to reduce the ascites volume and inhibit the increases in the wet pancreatic weight. Edaravone also tended to reduced the microscopic mucosal damage scores and pancreatic tissue lipid peroxide levels. In particular, the serum amylase levels in the edaravone-treated rats (1-20 mg/kg i.v.) were significantly reduced as compared to the vehicle-treated rats. These results strongly support the involvement of ROS in the pathogenesis of CDL-induced acute pancreatitis and cytoprotective effects of free radical scavender against pancreatic acinar cells. A clinical effect for edaravone against acute pancreatitis is strongly expected.