Objectives Calcitonin gene-related peptide alpha (αCGRP) represents an immunomodulatory neuropeptide implicated in pain perception. αCGRP also functions as a critical regulator of bone formation and is overexpressed in patients with rheumatoid arthritis (RA). In the present study, we investigated the role of αCGRP in experimental RA regarding joint inflammation and bone remodelling. Methods Collagen II-antibody-induced arthritis (CAIA) was induced in wild type (WT) and αCGRP-deficient (αCGRP-/-) mice. Animals were monitored over 10 and 48 days with daily assessments of the semiquantitative arthritis score and grip strength test. Joint inflammation, cartilage degradation and bone erosions were assessed by histology, gene expression analysis and µCT. Results CAIA was accompanied by an overexpression of αCGRP in WT joints. αCGRP-/- mice displayed reduced arthritic inflammation and cartilage degradation. Congruently, the expression of TNF-α, IL-1β, CD80 and MMP13 was induced in WT, but not αCGRP-/- animals. WT mice displayed an increased bone turnover during the acute inflammatory phase, which was not the case in αCGRP-/- mice. Interestingly, WT mice displayed a full recovery from the inflammatory bone disease, whereas αCGRP-/- mice exhibited substantial bone loss over time. Conclusion This study demonstrates a proinflammatory and bone protective role of αCGRP in CAIA. Our data indicate that αCGRP not only enhances joint inflammation, but also controls bone remodelling as part of arthritis resolution. As novel αCGRP inhibitors are currently introduced clinically for the treatment of migraine, their potential impact on RA progression warrants further clinical investigation.

Highlights CT levels are increased systemically during acute experimental RA CTR is primarily expressed in the superficial articular cartilage layer in CAIA In CAIA CTR-deficiency is associated with increased inflammation marker expression Bone architecture is impaired in experimental RA when CTR signaling is disrupted

ObjectivesOne major goal of the emergency department (ED) is to decide, whether patients need to be hospitalised or can be sent home safely. We aim at providing criteria for these decisions without knowing the SARS-CoV-2 test result in suspected cases.SettingTertiary emergency medicine.ParticipantsAll patients were treated at the ED of the Charité during the pandemic peak and underwent SARS-CoV-2 testing. Patients with positive test results were characterised in detail and underwent a 14-day-follow-up.Primary and secondary outcome measuresLogistic regression and classification and regression tree (CART) analyses were performed to identify predictors (primary endpoint), which confirm safe discharge. The clinical endpoint was all-cause mortality or need for mechanical ventilation during index stay or after readmission.ResultsThe primary test population of suspected COVID-19 consisted of n=1255 cases, 45.2% were women (n=567). Of these, n=110 tested positive for SARS-CoV-2 (8.8%). The median age of SARS-CoV-2-positive cases was 45 years (IQR: 33–66 years), whereas the median age of the group tested negative for SARS-CoV-2 was 42 years (IQR: 30–60 years) (p=0.096). 43.6% were directly admitted to hospital care.CART analysis identified the variables oxygen saturation (<95%), dyspnoea and history of cardiovascular (CV) disease to distinguish between high and low-risk groups. If all three variables were negative, most patients were discharged from ED, and the incidence of the clinical endpoint was 0%. The validation cohort confirmed the safety of discharge using these variables and revealed an incidence of the clinical endpoint from 14.3% in patients with CV disease, 9.4% in patients with dyspnoea and 18.2% in patients with O2 satuaration below 95%.ConclusionsBased on easily available variables like dyspnoea, oxygen saturation, history of CV disease, approximately 25% of patients subsequently confirmed with COVID-19 can be identified for safe discharge.Trial registration numberDRKS00023117.