Search

Summary: Background: Schnitzler syndrome (SchS) is a rare autoinflammatory disease characterized by urticarial exanthema, bone and joint alterations, fever and monoclonal gammopathy, which manifest mostly in the second half of life. It involves overactivation of the interleukin (IL)‐1 system, but the exact pathophysiological pathways remain largely unknown. Objectives: To identify and characterize the pathogenetic players in SchS. Methods: Blood parameters were quantified in patients with SchS compared with healthy controls and patients with psoriasis and hidradenitis suppurativa using enzyme‐linked immunosorbent assay (ELISA). CCL2 expression in cultured primary cells was analysed by quantitative reverse‐transcriptase polymerase chain reaction and ELISA. Results: CCL2, a chemoattractant for monocytic and further mononuclear immune cells, was found to be significantly elevated in patients with SchS. CCL2 levels showed a positive association with global disease activity, especially with bone pain, but not disease duration, gammopathy, neutrophilia or skin disease. In vitro stimulation assays demonstrated a strong CCL2 production capacity of mononuclear immune cells and fibroblasts, but not epithelial or endothelial cells. Among a range of inflammatory mediators, only IL‐1β (immune cells, fibroblasts) and tumour necrosis factor (TNF)‐α (fibroblasts) were important CCL2 inducers. TNF‐α, but not IL‐17, strengthened the CCL2‐inducing effect of IL‐1β in fibroblasts. Accordingly, CCL2 levels positively correlated with both TNF‐α and IL‐1β serum levels in patients with SchS. Therapeutic IL‐1β blockade decreased CCL2 blood levels in these patients as early as 1 week after the initiation of treatment. Conclusions: CCL2 may be an important component of the pathogenetic cascade leading to bone alterations, and a suitable marker of disease activity in patients with SchS. What's already known about this topic?Schnitzler syndrome (SchS) is a very rare acquired autoinflammatory disease, clinically characterized by urticarial exanthema, arthralgia and osteosclerosis, and episodes of fever.The pathogenesis involves overactivation of the interleukin‐1 system.The exact pathogenetic pathways are mostly unknown, and biomarkers are not available to assess the inflammatory activity in SchS. What does this study add? The chemokine CCL2 is a marker of SchS; its blood levels are significantly upregulated and linked to global disease activity and early therapy response in patients with SchS.While no clear relationship with patients' urticarial exanthema was detected, CCL2 may be involved in bone alterations in these patients.The cellular sources of CCL2 include mononuclear immune cells and fibroblasts.Interleukin‐1β and tumour necrosis factor‐α, blood levels of which correlate with CCL2 levels in patients with SchS, are important CCL2 inducers. What is the translational message? Quantifying CCL2 blood levels may allow the objective estimation of inflammatory disease activity and may help with the therapy decision in patients with SchS.CCL2 may be a key element of the pathogenetic cascades in SchS, especially those important for osteosclerosis. Linked Comment:Kambe and Nguyen. Br J Dermatol 2019; 180:706–707. Respond to this article Plain language summary available online [ABSTRACT FROM AUTHOR]

A letter to the editor on benefit of doxycycline therapy in patients with chronic cold urticaria is presented.

A letter to the editor is presented which discusses the cases of a 73-year-old woman and a 61-year-old woman with notalgia paraesthetica (NP) who both undergo treatment of the disease with an 8% capsaicin patch.

The article discusses the use of skin biomarker profiles to distinguish Schnitzler syndrome from chronic spontaneous urticaria. It mentions immunohistochemistry of skin cytokines presented significantly higher numbers of IL-6-positive cells in SchS. It also mentions the need of evaluation of these biomarkers in patients and along with characterization of the role of mast cells and neutrophils in auto inflammatory diseases.

We report the case of a pigeon keeper with CD4 lymphopenia, not associated with human immunodeficiency virus infection, who developed primary cutaneous cryptococcosis at the site of a pigeon peck. [ABSTRACT FROM AUTHOR]

Linked Article: Krause et al. Br J Dermatol 2019; 180:859–868 [ABSTRACT FROM AUTHOR]

Summary: Schnitzler syndrome is a very rare chronic disease, which usually develops in the second half of life. It appears as skin rashes, muscle/skeletal pain and fever episodes. The trigger and molecular processes in the disease are not understood. However, drugs that inhibit the inflammatory molecule called interleukin‐1ß were found to relieve the disease. The authors of this German study wondered which further molecules are involved in Schnitzler syndrome. For this purpose, a range of molecules with inflammatory properties was quantified in the blood of the patients and, as a comparison, in healthy people and patients with other inflammatory diseases. Patients with Schnitzler syndrome were found to have strongly elevated levels of CCL2, a molecule known to attract inflammatory cells to affected tissues and to have a special role in bone alterations. CCL2 levels were particularly high in severely affected patients, especially those with intense bone pain. In the bone, CCL2 is known to be produced by certain bone‐modifying cells. Laboratory experiments revealed that CCL2 was also highly produced by immune cells and connective tissue cells (fibroblasts). Interleukin‐1ß as well as the inflammatory molecule TNF‐α triggered the production of CCL2 by these cells. When patients were treated with an interleukin‐1ß‐blocking drug, health improvement was paralleled by a drop of CCL2 levels. The authors concluded that in Schnitzler syndrome CCL2 is an important player in the inflammation process in bones and other body sites and may be used in the clinic as an indicator of disease severity. Linked Article: Krause et al. Br J Dermatol 2019; 180:859–868 [ABSTRACT FROM AUTHOR]