Eosinophilic fasciitis (Shulman syndrome)-recognition of the histological spectrum allows for new insights into possible pathomechanisms.

OBJECTIVES: EF is a rare disease characterized by fibrosis and inflammation of the fascia, scleroderma-like skin indurations and optional blood eosinophilia. We aimed to expand the knowledge about its aetiology and pathogenesis. METHODS: Biopsy specimens from 16 EF patients were assessed by histology, immunohistochemistry and quantitative reverse transcription PCR in comparison with anti-Mi-2+ DM patients and non-disease controls. RESULTS: Histologically, EF shows mild to severe inflammation at the muscle-fascia interface, with frequent involvement of the underlying muscle tissue, though varying in degree. CD206+ macrophages predominate and eosinophils are detected within the fascia in the majority of cases, however in quite small numbers, and seen infrequently within the muscle. Activators of the so-called Th2-M2 pathway like STAT6 and IL-4 are upregulated leading to high expression levels of CD206. Activators of the so-called Th1-M1 pathway like STAT1 and IFN-γ (IFNG) are also upregulated, though not translating into a significant upregulation of the effector molecule COX2. Interestingly, activators or chemoattractants of eosinophils show no significant upregulation in EF compared with DM. EF shows features of perifascicular pathology comparable to DM, with upregulation of MHC class I and II; however, this is not accompanied by perifascicular atrophy or any signs of a type I IFN response or hypoxia-mediated processes. CONCLUSIONS: Our findings highlight a specific immune phenotype of leucocyte infiltrates in EF along features of perifascicular pathology similar to DM, while there is no evidence of hypoxia-mediated or type I IFN-associated processes with perifascicular fibre atrophy, indicating different pathomechanisms of muscle involvement.

SIGLEC1 (CD169): a marker of active neuroinflammation in the brain but not in the blood of multiple sclerosis patients.

We aimed to evaluate SIGLEC1 (CD169) as a biomarker in multiple sclerosis (MS) and Neuromyelitis optica spectrum disorder (NMOSD) and to evaluate the presence of SIGLEC1+ myeloid cells in demyelinating diseases. We performed flow cytometry-based measurements of SIGLEC1 expression on monocytes in 86 MS patients, 41 NMOSD patients and 31 healthy controls. Additionally, we histologically evaluated the presence of SIGLEC1+ myeloid cells in acute and chronic MS brain lesions as well as other neurological diseases. We found elevated SIGLEC1 expression in 16/86 (18.6%) MS patients and 4/41 (9.8%) NMOSD patients. Almost all MS patients with high SIGLEC1 levels received exogenous interferon beta as an immunomodulatory treatment and only a small fraction of MS patients without interferon treatment had increased SIGLEC1 expression. In our cohort, SIGLEC1 expression on monocytes was-apart from those patients receiving interferon treatment-not significantly increased in patients with MS and NMOSD, nor were levels associated with more severe disease. SIGLEC1+ myeloid cells were abundantly present in active MS lesions as well as in a range of acute infectious and malignant diseases of the central nervous system, but not chronic MS lesions. The presence of SIGLEC1+ myeloid cells in brain lesions could be used to investigate the activity in an inflammatory CNS lesion.