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Blau syndrome is a systemic autoinflammatory granulomatous disease caused by mutations in the nucleotide-binding oligomerization domain 2 (NOD2) gene. NOD2 is an intracellular pathogen recognition receptor. Upon binding to muramyl dipeptide (MDP), NOD2 activates the NF-κB pathway, leading to the upregulation of proinflammatory cytokines. Clinical manifestations of Blau syndrome appear in patients before the age of four. Skin manifestations resolve spontaneously in some cases; however, joint and eye manifestations are progressive, and lead to serious complications, such as joint contracture and blindness. Currently, there is no specific curative treatment for the disease. Administration of high-dose oral steroids can improve clinical manifestations; however, treatments is difficult to maintain due to the severity of the side effects, especially in children. While several new therapies have been reported, including JAK inhibitors, anti-IL-6 and anti-IL-1 therapies, anti-TNF therapy plays a central role in the treatment of Blau syndrome. We recently performed an ex vivo study, using peripheral blood and induced pluripotent stem cells from patients. This study demonstrated that abnormal cytokine expression in macrophages from untreated patients requires IFNγ stimulation, and that anti-TNF treatment corrects the abnormalities associated with Blau syndrome, even in the presence of IFNγ. Therefore, although the molecular mechanisms by which the genetic mutations in NOD2 lead to granuloma formation remain unclear, it is possible that prior exposure to TNFα combined with IFNγ stimulation may provide the impetus for the clinical manifestations of Blau syndrome.

is 265 times the current exposure limit value of 23 mJ cm À2 at 222 nm. 7 Therefore, even at very high exposure doses, appropriately filtered far-UVC is unlikely to present a carcinogenic risk through direct DNA damage. These important but preliminary results are very encouraging. As recently advised and encouraged by the UK's Scientific Advisory Group for Emergencies we are continuing with multiple far-UVC research projects to investigate the efficacy and safety profile of this very promising technology. 8 However, to date, the evidence is overwhelmingly in favour of using filtered far-UVC as a safe, effective germicidal technology.

Schnitzler syndrome is characterized by chronic urticarial rash, neutrophilic dermal infiltrate, recurrent fever, bone pain, elevated C‐reactive protein, and neutrophilic leukocytosis. The pathophysiology of Schnitzler syndrome is unknown, but it is considered to be an acquired form of an autoinflammatory disease because of the resemblance to clinical phenotypes of cryopyrin‐associated periodic syndrome, in which a gain‐of‐function mutation in NLRP3 causes overexpression of interleukin (IL)‐1β. Schnitzler syndrome is generally accompanied by a monoclonal immunoglobulin (Ig)M gammopathy with a long‐term risk of lymphoproliferation that is possibly associated with an MYD88 mutation. Herein, we present the following four patients with Schnitzler syndrome: a 63‐year‐old woman; a 65‐year‐old man; a 43‐year‐old woman; and a 63‐year‐old woman. Each patient fulfilled the Strasbourg diagnostic criteria, but none of the patients had any mutation in NLRP3 or MYD88 detected in their peripheral blood. Although approved treatment options for Schnitzler syndrome are lacking, our patients were treated with IL‐1‐targeted therapy (anakinra or canakinumab) or anti‐IL‐6 (tocilizumab). The acute inflammatory clinical manifestations improved completely with canakinumab and partially with anakinra and tocilizumab, but the serum IgM levels were gradually increased in all patients, even during treatment. To determine whether treatment with anti‐IL‐1β or IL‐6 prevents conversion to a hematopoietic disorder, further collection of cases and long‐term follow‐up will be needed.

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