The specialized pro-resolving lipid mediator Protectin D1 affects macrophages differentiation and activity in Adult-onset Still's disease and COVID-19, two hyperinflammatory diseases sharing similar transcriptomic profiles.

Introduction: COVID-19 and autoinflammatory diseases, such as Adult-onset Still's Disease (AOSD), are characterized by hyperinflammation, in which it is observed massive production and uncontrolled secretion of pro-inflammatory cytokines. The specialized pro-resolving lipid mediators (SPMs) family is one the most important processes counteracting hyperinflammation inducing tissue repair and homeostasis restoration. Among SPMs, Protectin D1 (PD1) is able to exert antiviral features, at least in animal models. The aim of this study was to compare the transcriptome of peripheral blood mononuclear cells (PBMCs) from patients with AOSD and COVID-19 and to evaluate the role of PD1 on those diseases, especially in modulating macrophages polarization. Methods: This study enrolled patients with AOSD, COVID-19, and healthy donors HDs, undergoing clinical assessment and blood sample collection. Next-generation deep sequencing was performed to identify differences in PBMCs transcripts profiles. Plasma levels of PD1 were assessed by commercial ELISA kits. Monocyte-derived macrophages were polarized into M1 and M2 phenotypes. We analyzed the effect of PD1 on macrophages differentiation. At 10 days, macrophages were analyzed for surface expression of subtypes markers by flow cytometry. Cytokines production was measured in supernatants by Bio-Plex Assays. Results: In the transcriptomes from AOSD patients and COVID-19 patients, genes involved in inflammation, lipid catabolism, and monocytes activation were specifically dysregulated in AOSD and COVID-19 patients when compared to HDs. Patients affected by COVID-19, hospitalized in intensive care unit (ICU), showed higher levels of PD1 when compared to not-ICU hospitalized patients and HDs (ICU COVID-19 vs not-ICU COVID-19, p= 0.02; HDs vs ICU COVID-19, p= 0.0006). PD1 levels were increased in AOSD patients with SS ≥1 compared to patients with SS=0 (p=0.028) and HDs (p=0.048). In vitro treatment with PD1 of monocytes-derived macrophages from AOSD and COVID-19 patients induced a significant increase of M2 polarization vs control (p<0.05). Furthermore, a significant release of IL-10 and MIP-1ß from M2 macrophages was observed when compared to controls (p<0.05). Discussion: PD1 is able to induce pro-resolutory programs in both AOSD and COVID-19 increasing M2 polarization and inducing their activity. In particular, PD1-treated M2 macrophages from AOSD and COVID-19 patients increased the production of IL-10 and enhanced homeostatic restoration through MIP-1ß production.

The similar expression of both ferritin and scavenger receptors activation genes in patients with COVID19 and AOSD support their role in the pathogenesis of these diseases and identify a common mechanism at the basis of the "hyperferritinemic syndromes".

A role for COVID19 in "hyperferritinemic syndromes" has been proposed based on its clinical and serological characteristics and its similarities with AOSD. To better understand the molecular pathways responsible of these similarities, we evaluated in the PBMCs of 4 active AOSD patients, 2 COVID19 patients with ARDS, and 2 HCs the expression of genes associated with iron metabolisms, with monocyte/macrophages activation, and finally with NETs formation.

Diagnosis of COVID-19 associated arthritis in patients with or without underlying rheumatic and musculoskeletal disease supported by musculoskeletal ultrasound: a case series from three European centres.

OBJECTIVES: The coronavirus disease 19 (COVID-19) pandemic concerns the field of rheumatology in many ways. Arthritis in conjunction with COVID-19 is increasingly reported. However, clinical data are still limited and there is lack of a detailed characterisation of COVID-19 associated arthritis by musculoskeletal ultrasound (MSUS). This case series reports different forms of COVID-19 associated arthritis supported by MSUS in patients with or without underlying rheumatic and musculoskeletal disease (RMD). METHODS: From March 2020 to July 2021, adult patients (n=10) with arthritis timely related to COVID-19 were assessed in three European centres by clinical and laboratory values and additionally MSUS. RESULTS: In the group without underlying RMD (n=6), two patients presented with polyarticular arthralgia during severe COVID-19, swelling was rarely seen and MSUS demonstrated arthritis only in a few joints affected. The other four patients showed arthritis four to 16 weeks after mild or moderate COVID-19 (without hospitalisation): polyarthritis (n=1), oligoarthritis of the upper and lower limb (n=2), and in one case, late-onset rheumatoid arthritis (LORA) was newly diagnosed. In the group with an underlying RMD (n=4), an increase of disease activity was reported by MSUS during mild and mild-moderate COVID-19. In general, MSUS often presented power Doppler (PD) positive synovitis and tenosynovitis. CONCLUSIONS: In our patients without underlying RMD, arthritides associated with COVID-19 are comparable to the clinical picture of a reactive arthritis (ReA) or other virus-related arthritides (e.g. parvovirus B19). New onset or flares of RMD possibly triggered by COVID-19 are noteworthy.