Nesting behavior is associated with body weight and grip strength loss in mice suffering from experimental arthritis.

Objective animal health evaluation is essential to determine welfare and discomfort in preclinical in vivo research. Body condition scores, body weight, and grimace scales are commonly used to evaluate well-being in murine rheumatoid arthritis (RA) and osteoarthritis experiments. However, nest-building, a natural behavior in mice, has not yet been evaluated in wild type (WT) or genetically modified rodents suffering from collagen antibody-induced arthritis (CAIA). To address this, we analyzed nesting behavior in WT mice, calcitonin gene-related peptide alpha-deficient (αCGRP-/-) mice, and calcitonin receptor-deficient (Calcr-/-) mice suffering from experimental RA compared to healthy control (CTRL) groups of the same genotypes. CAIA was induced in 10-12-week-old male mice, and clinical parameters (body weight, grip strength, clinical arthritis score, ankle size) as well as nesting behavior were assessed over 10 or 48 days. A slight positive association between the nest score and body weight and grip strength was found for animals suffering from CAIA. For the clinical arthritis score and ankle size, no significant associations were observed. Mixed model analyses confirmed these associations. This study demonstrates that clinical effects of RA, such as loss of body weight and grip strength, might negatively affect nesting behavior in mice. Assessing nesting behavior in mice with arthritis could be an additional, non-invasive and thus valuable health parameter in future experiments to monitor welfare and discomfort in mice. During severe disease stages, pre-formed nest-building material may be provided to animals suffering from arthritis.

The dual pro-inflammatory and bone-protective role of calcitonin gene-related peptide alpha in age-related osteoarthritis.

BACKGROUND: The vasoactive neuropeptide calcitonin gene-related peptide alpha (αCGRP) enhances nociception in primary knee osteoarthritis (OA) and has been shown to disrupt cartilage and joint integrity in experimental rheumatoid arthritis (RA). Little is known about how αCGRP may alter articular structures in primary OA. We investigated whether αCGRP modulates local inflammation and concomitant cartilage and bone changes in a murine model of age-dependent OA. METHODS: Sixteen- to 18-month-old αCGRP-deficient mice (αCGRP-/-aged) were compared to, first, age-matched wild type (WTaged) and, second, young 4- to 5-month-old non-OA αCGRP-deficient (αCGRP-/-CTRL) and non-OA WT animals (WTCTRL). αCGRP levels were measured in serum. Knee and hip joint inflammation, cartilage degradation, and bone alterations were assessed by histology (OARSI histopathological grading score), gene expression analysis, and µ-computed tomography. RESULTS: WTaged mice exhibited elevated αCGRP serum levels compared to young WTCTRL animals. Marked signs of OA-induced cartilage destruction were seen in WTaged animals, while αCGRP-/-aged mice were mostly protected from this effect. Age-dependent OA was accompanied by an increased gene expression of pro-inflammatory Tnfa, Il1b, and Il6 and catabolic Mmp13, Adamts5, Ctsk, Tnfs11 (Rankl), and Cxcl12/Cxcr4 in WTaged but not in αCGRP-/-aged mice. αCGRP-deficiency however further aggravated subchondral bone sclerosis of the medial tibial plateau and accelerated bone loss in the epi- and metaphyseal trabecular tibial bone in age-dependent OA. CONCLUSIONS: Similar to its function in experimental RA, αCGRP exerts a dual pro-inflammatory and bone-protective function in murine primary OA. Although anti-CGRP treatment was previously not successful in reducing pain in OA clinically, these data underline a crucial pathophysiological role of αCGRP in age-related OA.

Inactivation of the gene encoding procalcitonin prevents antibody-mediated arthritis.

BACKGROUND: Procalcitonin (PCT) is applied as a sensitive biomarker to exclude bacterial infections in patients with rheumatoid arthritis (RA) flare-ups. Beyond its diagnostic value, little is known about the pathophysiological role of PCT in RA. METHODS: Collagen antibody-induced arthritis (CAIA) was induced in Calca-deficient mice (Calca-/-), lacking PCT (n = 15), and wild-type (WT) mice (n = 13), while control (CTRL) animals (n = 8 for each genotype) received phosphate-buffered saline. Arthritis severity and grip strength were assessed daily for 10 or 48 days. Articular inflammation, cartilage degradation, and bone lesions were assessed by histology, gene expression analysis, and µ-computed tomography. RESULTS: Serum PCT levels and intra-articular PCT expression increased following CAIA induction. While WT animals developed a full arthritic phenotype, Calca-deficient mice were protected from clinical and histological signs of arthritis and grip strength was preserved. Cartilage turnover markers and Tnfa were exclusively elevated in WT mice. Calca-deficient animals expressed increased levels of Il1b. Decreased bone surface and increased subchondral bone porosity were observed in WT mice, while Calca-deficiency preserved bone integrity. CONCLUSION: The inactivation of Calca and thereby PCT provided full protection from joint inflammation and arthritic bone loss in mice exposed to CAIA. Together with our previous findings on the pathophysiological function of Calca-derived peptides, these data indicate an independent pro-inflammatory role of PCT in RA.

Standardized protocol and outcome measurements for the collagen antibody-induced arthritis mouse model.

The murine collagen antibody-induced arthritis (CAIA) model resembles various features of human rheumatoid arthritis and is based on the intraperitoneal or intravenous injection of autoantibodies against type II collagen. Here, we present a standardized protocol for the intraperitoneal injection of arthritis-inducing autoantibodies in mice, followed by a description of daily arthritis assessments. We then detail the steps to harvest joint and bone tissues for histological, radiological, and molecular analyses. We highlight animal welfare and 3R considerations for experimental arthritis studies. For complete details on the use and execution of this protocol, please refer to Maleitzke et al. (2021, 2022).

The calcitonin receptor protects against bone loss and excessive inflammation in collagen antibody-induced arthritis.

Pharmacological application of teleost calcitonin (CT) has been shown to exert chondroprotective and anti-resorptive effects in patients with rheumatoid arthritis (RA). However, the role of endogenous CT that signals through the calcitonin receptor (CTR) remains elusive. Collagen II antibody-induced arthritis (CAIA) was stimulated in wild type (WT) and CTR-deficient (Calcr-/-) mice. Animals were monitored over 10 or 48 days. Joint inflammation, cartilage degradation, and bone erosions were assessed by clinical arthritis score, histology, histomorphometry, gene expression analysis, and µ-computed tomography. CAIA was accompanied by elevated systemic CT levels and CTR expression in the articular cartilage. Inflammation, cartilage degradation, and systemic bone loss were more pronounced in Calcr-/- CAIA mice. Expression of various pro-inflammatory, bone resorption, and catabolic cartilage markers were exclusively increased in Calcr-/- CAIA mice. Endogenous CT signaling through the mammalian CTR has the potential to protect against joint inflammation, cartilage degradation, and excessive bone remodeling in experimental RA.

Which parameters support disposition decision in suspected COVID-19 cases in the emergency department (ED): a German clinical cohort study.

OBJECTIVES: One 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. SETTING: Tertiary emergency medicine. PARTICIPANTS: All 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 MEASURES: Logistic 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. RESULTS: The 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%. CONCLUSIONS: Based 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 NUMBER: DRKS00023117.

Proinflammatory and bone protective role of calcitonin gene-related peptide alpha in collagen antibody-induced arthritis.

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-1ß, 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.