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Interactions between the epidermis and the immune system govern epidermal tissue homeostasis. These epidermis-immune interactions are altered in the inflammatory disease psoriasis; however, the pathways that underlie this aberrant immune response are not well understood. Here, we determined that Ras-related C3 botulinum toxin substrate 1 (RAC1) is a key mediator of epidermal dysfunction. RAC1 activation was consistently elevated in psoriatic epidermis and primary psoriatic human keratinocytes (PHKCs) exposed to psoriasis-related stimuli, but not in skin from patients with basal or squamous cell carcinoma. Expression of a constitutively active form of RAC1 ([RAC.sup.V12]) in mice resulted in the development of lesions similar to those of human psoriasis that required the presence of an intact immune system. [RAC1.sup.V12]-expressing mice and human psoriatic skin showed similar RAC1-dependent signaling as well as transcriptional overlap of differentially expressed epidermal and immune pathways. Coculture of PHKCs with immunocytes resulted in the upregulation of RAC1-dependent proinflammatory cytokines, an effect that was reproduced by overexpressing RAC1 in normal human keratinocytes. In keratinocytes, modulating RAC1 activity altered differentiation, proliferation, and inflammatory pathways, including STAT3, NFκB, and zinc finger protein 750 (ZNF750). Finally, RAC1 inhibition in xenografts composed of human PHKCs and immunocytes abolished psoriasiform hyperplasia and inflammation in vivo. These studies implicate RAC1 as a potential therapeutic target for psoriasis and as a key orchestrator of pathologic epidermis-immune interactions., Introduction Interactions between cutaneous epithelia and the immune system are vital for maintaining epidermal tissue homeostasis, skin barrier integrity, and immunocyte responses (1). Disruption of this interplay can lead to [...]

Pemphigus vulgaris (PV) is an autoimmune blistering disease of skin and mucous membranes caused by autoantibodies to the desmoglein (DSG) family proteins DSG3 and DSG1,1eading 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 cisadhesive 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., Introduction Pemphigus vulgaris (PV) is a life-threatening autoimmune blistering disease of skin and mucous membranes caused by autoantibodies that bind to the cadherin-type cell-cell adhesion molecules desmoglein 3 (DSG3) and [...]

Byline: Haruna. Goto-Hamano, Keiko. Ito, Kumiko. Sakamoto-Kimura, Tadashi. Terui, Bungo. Ohyama, Takashi. Hashimoto, Hiroyuki. Hara We report a 79-year-old Japanese man who developed subepidermal blistering skin disease after an 8-year [...]

Although rare, tuberculosis has been reported with biologic treatment against psoriasis in Japan, a tuberculosis medium‐burden country. Mycobacterial infection often develops after a long incubation period and might not have been adequately identified in clinical trials or post‐marketing surveillance. To determine the real‐world incidence of tuberculosis in psoriatic patients treated with biologics, we conducted a retrospective, multicenter, observational study in 18 facilities in Western Japan. Psoriatic patients who visited a participating facility between 2010 and March 2017 and received biologic reagents were enrolled. Information on sex, age at first biologic treatment, results of interferon‐γ release assay (IGRA) for Mycobacterium tuberculosis, treatment history with isoniazid, and onset of active and/or latent tuberculosis was collected. A total of 1117 patients (830 men and 287 women) were enrolled. The mean duration of biologic treatment was 3.54 years. Sixty‐five patients (5.8%) showed positive IGRA results at screening. Active tuberculosis developed in two patients after the administration of tumor necrosis factor inhibitors (both involved miliary tuberculosis). Latent tuberculosis was observed in two patients treated with anti‐interleukin‐12/23p40 antibody. The incidence rate of tuberculosis, including latent tuberculosis, in this survey was 0.36%. Although the incidence rate of tuberculosis was low considering the observation period of biologic treatment, active tuberculosis was found in both the screening‐negative group and a screening‐positive subject after isoniazid prophylaxis (both miliary tuberculosis), concluding that negative screening or isoniazid treatment does not always assure that an individual has no tuberculosis. Hence, dermatologists still need to pay careful attention to tuberculosis at every patient visit. [ABSTRACT FROM AUTHOR]

Background: Real-world data differ from clinical trial data. Although some real-world data regarding apremilast use for psoriasis treatment has been reported in Western countries, no such data has been reported in Asian countries. Objective: To study the efficacy, including Psoriasis Area and Severity Index (PASI) and drug survival, and safety of apremilast in Japanese patients with psoriasis. Methods: Data on all the patients treated with apremilast in Kurume University Hospital between May 2017 and June 2018 were retrieved, with June 30 2018, as the data lock date. Efficacy was analyzed by PASI50, PASI75, and PASI90; drug survival by Kaplan–Meier analysis; and drug safety by the proportion of adverse events (AEs). Results: Fourteen of 42 (33.3%) patients achieved PASI75/90; 16 (32%) patients had discontinued apremilast by the data lock date. Drug survival at week 28 was 70%. No serious AEs were reported; the most prevalent one was loose stools/diarrhea (60%), followed by nausea (38%). The most common reason for apremilast discontinuation was primary/secondary failure. Conclusions: Apremilast is safe and effective in Japanese patients with psoriasis. Higher occurrence of loose stools/diarrhea was noted in our cohort than that reported in Western real-world studies on apremilast. [ABSTRACT FROM AUTHOR]

Background: In Japan, more than five years have passed since emergence of the first three biologics, infliximab, adalimumab, and ustekinumab, became available in daily practice; however, no data for drug survival was reported from Japan. Objective: To study the long-term drug survival of infliximab, adalimumab, and ustekinumab used for Japanese psoriatic patients. Methods: We retrieved data on all patients treated with biological agents and calculated the long-term drug survival for infliximab, adalimumab, and ustekinumab using our psoriasis registry (Kurume Psoriasis Registry: KURUPR) consisted of 343 patients by the end of March 2017. We analyzed 103 treatment courses of 83 patients with all types of psoriasis, as well as 79 treatment courses of 62 patients with psoriasis vulgaris using the Kaplan-Meier method. Results: Drug survival was higher for ustekinumab than infliximab and adalimumab in both settings, although there were no statistical differences. Conclusions: Previous studies of long-term drug survival in patients with psoriasis vulgaris showed significantly higher drug survival for ustekinumab than infliximab, and adalimumab. Our data showed similar tendency. Besides randomized clinical trials, drug survival data is useful because it reflects real-world management. [ABSTRACT FROM AUTHOR]