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Mohamed S Numan,1,2 Nathalie Amiable,1 Jacques P Brown,1–3 Laëtitia Michou1–3 1CHU de Québec Research Centre, 2Division of Rheumatology, Department of Medicine, 3Department of Rheumatology, CHU de Québec-Université Laval, Quebec City, QC, Canada Abstract: Osteoimmunology represents a large area of research resulting from the cross talk between bone and immune systems. Many cytokines and signaling cascades are involved in the field of osteoimmunology, originating from various cell types. The RANK/receptor activator of nuclear factor Kappa-B ligand (RANKL)/osteoprotegerin (OPG) signaling has a pivotal role in osteoimmunology, in addition to proinflammatory cytokines such as tumor necrosis factor-α, interleukin (IL)-1, IL-6, and IL-17. Clinically, osteoimmunological disorders, such as rheumatoid arthritis, osteoporosis, and periodontitis, should be classified according to their pattern of osteoimmunological serum biomarkers. Paget’s disease of bone is a common metabolic bone disorder, resulting from an excessively increased bone resorption coupled with aberrant bone formation. With the exception of the cellular responses to measles virus nucleocapsid protein and the interferon-gamma signature, the exact role of the immune system in Paget’s disease of bone is not well understood. The cytokine profiles, such as the increased levels of IL-6 and the interferon-gamma signature observed in this disease, are also very similar to those observed in other osteoimmunological disorders. As a potential osteoimmunological disorder, the treatment of Paget’s disease of bone may also benefit from progress made in targeted therapies, in particular for receptor activator of nuclear factor Kappa-B ligand and IL-6 signaling inhibition. Keywords: Paget’s disease of bone, SQSTM1/p62, osteoimmunology, osteoclast, RANKL

Polypharmacy can be associated with poor outcomes in chronic diseases. Our objective is to determine the prevalence of polypharmacy and its association with disease control in patients with rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). An observational study was conducted using the SARD database of the CHU de Québec. Participants newly diagnosed with RA or SLE enrolled in the database after 24 months were included. Collected data included number and type of medications, Charlson Comorbidity Index, and medication adherence (proportion of days covered during the first 180 days). Polypharmacy was defined as the simultaneous use ≥5 medications. Multivariable logistic and linear regressions were used to determine the association between polypharmacy and disease control (DAS28CRP, SLEDAI-2 K). The study included 111 participants (RA = 81; SLE = 30). Medication count increased at two years in RA (mean ± SD): 4.6 ± 3.3 to 6.9 ± 3.6; and SLE: 6.5 ± 4.6 to 7.80 ± 4.82. Polypharmacy prevalence increased at two years: RA: from 43 to 74%; SLE: from 47 to 73%. Mean medication adherence exceeded 85%. For RA participants, polypharmacy was associated with a better DAS28CRP score at one year [adjusted odds ratio of achieving a poor outcome: 0.17 (95%CI 0.04-0.71)], but this association was lost at two years [2.88 (0.45-18.29)]. For SLE, polypharmacy was not associated with disease activity based on the SLEDAI-2 K at one year [7.36 (0.26-211.16)] or two years [0.32 (0.05-1.99)]. Overall, polypharmacy is very prevalent in RA and SLE and could be positively associated with the level of disease control in the year after a diagnosis of RA., Competing Interests: Declarations. Conflict of interest: The authors declare no conflicts of interest. Use of artificial intelligence: This article was written without the use of artificial intelligence and has not been reviewed by a commercial editing service. Congress abstract publication: An earlier version of the abstract before final analysis was presented at the Canadian Rheumatology Association 2023 Annual Scientific Meeting: Berthelot W, Sirois C, Julien AS, Amiable N, Fortin PR (2023) Polypharmacy in Systemic Autoimmune Rheumatic Diseases. Canadian Rheumatology Association Meeting Quebec City Convention Centre Quebec City, Quebec, Canada February 8–11, 2023. J Rheumatol 50(7 Suppl 1):7-100. https://doi.org/10.3899/jrheum.2023-0216 ., (© 2025. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Objective: To assess the safety, immunogenicity and cellular responses following the Moderna Spikevax primary series in rheumatic disease., Methods: We conducted a 12-month, prospective, non-randomised, open-label, comparative trial of adults with either rheumatoid arthritis (RA, n=131) on stable treatment; systemic lupus erythematosus (SLE, n=23) on mycophenolate mofetil (MMF); other rheumatic diseases on prednisone ≥10 mg/day (n=8) or age-matched/sex-matched controls (healthy control, HC, n=58). Adverse events (AEs), humoral immune responses (immunogenicity: IgG positivity for anti-SARS-CoV-2 spike protein and its receptor binding domain, neutralising antibodies (NAbs)), cellular responses (ELISpot) and COVID-19 infection rates were assessed., Results: Frequency of solicited self-reported AEs following vaccination was similar across groups (HC 90%, RA 86%, SLE 90%); among them, musculoskeletal AEs were more frequent in RA (HC 48% vs RA 66% (Δ95% CI CI 3 to 32.6)). Disease activity scores did not increase postvaccination. No vaccine-related serious AEs were reported. Postvaccination immunogenicity was reduced in RA and SLE (RA 90.2%, SLE 86.4%; for both, ΔCIs compared with HC excluded the null). Similarly, NAbs were reduced among patients (RA 82.6%, SLE 81.8%). In RA, age >65 (OR 0.3, 95% CI 0.1 to 0.8) and rituximab treatment (OR 0.003, 95% CI 0.001 to 0.02) were negative predictors of immunogenicity. ELISpot was positive in 16/52 tested RA and 17/26 HC (ΔCI 11.2-53.3). During the study, 11 HC, 19 RA and 3 SLE patients self-reported COVID-infection., Conclusion: In COVID-19 Vaccine in Immunosuppressed Adults with Autoimmune Diseases, the Moderna Spikevax primary series was safe. MMF, RA age >65 and rituximab were associated with reduced vaccine-induced protection., Competing Interests: Competing interests: IC, VV, NA, MU, ER, LF, ER-L, M-AF, EH, DM, LM, PP, M-AL, SB, PRF—no competing interests. LB received grants or has contracts with Amgen, BMS, Janssen, UCB, AbbVie, Pfizer, Merck, Celgene, Sanofi, Lilly, Novartis, Gilead, JAMP Pharma., (© Author(s) (or their employer(s)) 2023. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)

The myeloid inhibitory receptor CLEC12A negatively regulates inflammation. Reduced CLEC12A expression enhances inflammation in CLEC12A knock-out mice with collagen antibody-induced arthritis. Moreover, CLEC12A internalisation augments human neutrophil activation. We thus postulated that CLEC12A expression on circulating myeloid cells of rheumatoid arthritis patients is associated with disease manifestations. Cell-surface, CLEC12A receptor expression was determined on circulating neutrophils and monocytes of eRA patients and of healthy donors. Generalized estimating equations model, Student's t-test and Spearman's correlations were performed to compare CLEC12A expression between groups and test its association with disease activity and clinical parameters. Plasma cytokines were measured by multiplex immunoassay. Patients with reduced neutrophil or monocyte CLEC12A expression at baseline and at 3 months have an increased simple disease activity index. Low baseline CLEC12A expression also correlates with a higher SDAI at 6 months. In contrast, positive correlations were observed between baseline CLEC12A expression and several cytokines. Moreover, neutrophil and monocyte CLEC12A expression is significantly higher in early rheumatoid arthritis patients at baseline than healthy controls. Circulating neutrophil and monocyte CLEC12A expression correlates with disease activity at baseline and is predictive of SDAI at later stages of the disease indicative of a regulatory role for CLEC12A in RA.

Sphingosine kinase 1 (SphK1) and 2 (SphK2) have been shown contribute to synovial inflammation in animal models of arthritis. However, low levels of intracellular sphingosine-1 phosphate (S1P) were reported in fibroblast-like synoviocytes (FLS) from patients in the end stage of rheumatoid arthritis (RA) compared to normal FLS. Moreover, the S1P receptor-mediated chemokine synthesis was altered in RAFLS in response to chemical hypoxia. Since the mechanisms responsible for low levels of intracellular S1P in RAFLS are not fully identified, we evaluated the contribution of SphKs to the S1P-induced synthesis of chemokines under conditions of chemical hypoxia. Our results show that a chemical hypoxia mimetic cobalt chloride (CoCl 2 ) increased SphK1 expression and activation in normal FLS but not in RAFLS. Using selective inhibitors of SphKs and gene silencing approaches, we provide evidence that both SphK1 and SphK2 are involved in hypoxia-induced chemokine production in normal FLS. In contrast, only SphK2 mediates hypoxia-induced chemokine production in RAFLS. Moreover, CoCl 2 increased S1P2 and S1P3 receptor mRNA levels in normal FLS but not in RAFLS. The data suggest that altered expression and/or activation of SphK1 combined with reduced induction of S1P receptor expression by CoCl 2 impaired the CoCl 2 -mediated autocrine S1P receptor signaling loop and chemokine production in RAFLS., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Objectives: This study explored the role of outdoor and indoor air pollutants in Paget's disease of bone (PDB)., Methods: We performed a survey in 140 French-Canadian patients with PDB, including 39 carriers of p.Pro392Leu mutation (SQSTM1 gene) and 113 healthy not mutated controls. The survey covered outdoor air pollution near the residence and indoor air pollutants by focusing on heating fuels and exposure to tobacco smoke. In a subgroup of patients, urinary concentrations of 17 heavy metals and 11 polycyclic aromatic hydrocarbons were measured by mass spectrometry. In light of what we learned from the survey and urinary assays, we explored the in vitro effects of certain toxics on osteoclasts in PDB. We conducted in vitro monocytes differentiation from peripheral blood of more than 40 participants, whose osteoclasts were treated with or without the toxic. The morphology of osteoclasts, their bone resorption abilities, gene and protein expression levels, and cellular oxidative stress levels were assayed., Results: An inhibitory effect of cigarette smoke condensate and heavy metals was observed on morphology and bone resorption activity of patients' osteoclasts. SQSTM1 gene expression was upregulated in osteoclasts from patients with PDB versus healthy controls in presence of cadmium, and SQSTM1 protein expression was upregulated in presence of bismuth and tobacco smoke condensates, in particular in osteoclasts from carriers of the SQSTM1 mutation. Furthermore, high levels of oxidative stress in patients' osteoclasts were observed., Conclusions: Our in vitro experiments suggest an interaction between SQSTM1 gene and exposure to cadmium and tobacco smoke condensates., (Copyright © 2018 Société française de rhumatologie. Published by Elsevier Masson SAS. All rights reserved.)

Background: Dendritic Cell-Specific Transmembrane Protein (DC-STAMP) is involved in osteoclastogenesis with a key role in mononucleated osteoclasts fusion. We reported in patients with Paget's disease of bone (PDB) a rare variant (rs62620995) in the TM7SF4 gene, encoding for DC-STAMP, which changes a highly conserved amino acid, possibly damaging according to in silico predictions. This study aimed at determining the functional effects of this variant on osteoclast phenotype in PDB., Methods: Fifty ml of peripheral blood were collected in pagetic patients carrier of this variant (n = 4) or not (n = 4) and healthy controls (n = 4). Monocytes were collected after Ficoll gradient and cultured in a medium containing RANKL (40 ng/ml) and hMCSF (25 ng/ml). At the end of the differentiation period, we assessed the osteoclast morphology and bone resorption abilities. We quantified gene expression of SQSTM1, DC-STAMP, OS9, CREB3, LAMP1, OC-STAMP, and NFATC1 genes from cell lysates. Proteins encoded by these genes were investigated by Western Blot. Statistical analyses relied on ANOVA followed by Tukey post-tests., Results: After 21 days of differentiation, the mean number of nuclei per multinucleated cell was significantly higher in pagetic patients carrier of the variant than in healthy controls. Bone resorption abilities were not modified by the variant. qPCR and Western Blot analyses did not provide any differences, but DC-STAMP expression was higher in patients carrier of the variant than in patients non carrier., Conclusions: This TM7SF4 rare variant may have an impact on osteoclast morphology and on DC-STAMP expression during osteoclastogenesis. Further analyses are required to understand the role of this variant during osteoclastogenesis in PDB.

Microbial agents can aggravate inflammatory diseases, such as multiple sclerosis (MS) and its animal model, experimental autoimmune encephalomyelitis (EAE). An example is pertussis toxin (PTX), a bacterial virulence factor commonly used as an adjuvant to promote EAE, but whose mechanism of action is unclear. We have reported that PTX triggers an IL-6-mediated signaling cascade that increases the number of leukocytes that patrol the vasculature by crawling on its luminal surface. In the present study, we examined this response in mice lacking either TLR4 or inflammasome components and using enzymatically active and inactive forms of PTX. Our results indicate that PTX, through its ADP-ribosyltransferase activity, induces two series of events upstream of IL-6: 1) the activation of TLR4 signaling in myeloid cells, leading to pro-IL-1β synthesis; and 2) the formation of a pyrin-dependent inflammasome that cleaves pro-IL-1β into its active form. In turn, IL-1β stimulates nearby stromal cells to secrete IL-6, which is known to induce vascular changes required for leukocyte adhesion. Without pyrin, PTX does not induce neutrophil adhesion to cerebral capillaries and is less effective at inducing EAE in transgenic mice with encephalitogenic T lymphocytes. This study identifies the first microbial molecule that activates pyrin, a mechanism by which infections may influence MS and a potential therapeutic target for immune disorders.

Objective: Evidence indicates that proteinase-activated receptor (PAR)-2 participates in the degradative processes of human osteoarthritis (OA). We evaluated the in vivo effect of PAR-2 on articular lesions in a PAR-2-knockout (KO) mouse model of OA., Methods: OA was surgically induced by destabilization of the medial meniscus of the right knee in C57Bl/6 wild-type (WT) and PAR-2 KO mice. Knee swelling was measured throughout the duration of the study (8 weeks postsurgery) and histologic evaluation of cartilage was done to assess structure, cellularity, matrix staining, and remodeling in the deep zone. Morphometric analysis of subchondral bone was also performed., Results: Data showed significant knee swelling in the operated WT mice immediately following surgery, which increased with time (8 weeks post-surgery). Knee swelling was significantly lower (p ≤ 0.0001) in PAR-2 KO mice than in WT mice at both 4 and 8 weeks postsurgery. Cartilage damage was found in both operated WT and PAR-2 KO mice; however, lesions were significantly less severe (global score; p ≤ 0.05) in the PAR-2 KO mice at 4 weeks postsurgery. Operated WT mice showed reduced subchondral bone surface and trabecular thickness with significance reached at 4 weeks (p ≤ 0.03 and p ≤ 0.05, respectively), while PAR-2 KO mice demonstrated a gradual increase in subchondral bone surface with significance reached at 8 weeks (p ≤ 0.007)., Conclusion: We demonstrated the in vivo implication of PAR-2 in the development of experimental OA, thus confirming its involvement in OA joint structural changes and reinforcing the therapeutic potential of a PAR-2 antagonist for treatment of OA.

Introduction: In osteoarthritis (OA), the subchondral bone undergoes a remodelling process involving several factors synthesized by osteoblasts. In this study, we investigated the expression, production, modulation, and role of PAR-2 in human OA subchondral bone osteoblasts., Materials and Methods: PAR-2 expression and production were determined by real-time PCR and flow cytometry, respectively. PAR-2 modulation was investigated in OA subchondral bone osteoblasts treated with IL-1 beta (100 pg/ml), TNF-alpha (5 ng/ml), TGF-beta1 (10 ng/ml), PGE(2) (500 nM), IL-6 (10 ng/ml) and IL-17 (10 ng/ml). Membranous RANKL protein was assessed by flow cytometry, and OPG, MMP-1, MMP-9, MMP-13, IL-6 and intracellular signalling pathways by specific ELISAs. Bone resorptive activity was measured by using a co-culture model of human PBMC and OA subchondral bone osteoblasts., Results: PAR-2 expression and production (p<0.05) were markedly increased when human OA subchondral bone osteoblasts were compared to normal. On OA osteoblasts, PAR-2 production was significantly increased by IL-1 beta, TNF-alpha and PGE(2). Activation of PAR-2 with a specific agonist, SLIGKV-NH(2), induced a significant up-regulation of MMP-1, MMP-9, IL-6, and membranous RANKL, but had no effect on MMP-13 or OPG production. Interestingly, bone resorptive activity was also significantly enhanced following PAR-2 activation. The PAR-2 effect was mediated by activation of the MAP kinases Erk1/2 and JNK., Conclusion: This study is the first to demonstrate that PAR-2 activation plays a role in OA subchondral bone resorption via an up-regulation of major bone remodelling factors. These results shed new light on the potential of PAR-2 as a therapeutic target in OA.

Introduction: Members of the ephrin system, the ephrin receptor erythropoietin-producing hepatocellular B4 (EphB4) and its specific ligand, ephrin B2, appear to be involved in the bone remodelling process. We recently showed that their interaction inhibits the resorptive activity of human osteoarthritic (OA) subchondral bone osteoblasts. Hence, we further investigated the possible implication of these ephrin members on the catabolic/anabolic activities of human OA chondrocytes., Methods: EphB4 receptor and ephrin B2 levels were determined by quantitative PCR and immunohistochemistry, and the effects of ephrin B2 on the expression/production of factors involved in the OA process., Results: EphB4 receptors and ephrin B2 ligands are expressed and produced by human normal and OA chondrocytes. Ephrin B2 protein was found at similar levels in both cartilage types, whereas EphB4 receptor expression (P < 0.0001) and production (P < 0.01) levels were significantly increased in OA chondrocytes/cartilage. Ephrin B2 treatment significantly inhibited the interleukin (IL)-1beta, IL-6, matrix metalloproteinase-1 (MMP-1), MMP-9, MMP-13, and proteinase-activated receptor-2 (PAR-2) gene expression levels, whereas MMP-2 was unaffected, and significantly increased collagen type II, a cartilage specific macromolecule. It also inhibited the IL-1beta stimulated protein production of IL-6, MMP-1 and MMP-13., Conclusions: Our study is the first to provide data on the presence and role of ephrin B2/EphB4 receptors in human chondrocytes/cartilage. Data showed that ephrin B2 treatment positively impacts the abnormal metabolism of OA cartilage by inhibiting important catabolic factors involved in this disease at the same time as increasing anabolic activity.

Objective: Abnormal subchondral bone metabolism is involved in osteoarthritis (OA). It has been suggested that ephrin B2 and its specific receptor EphB4 participate in bone homeostasis. We previously reported that human OA subchondral bone osteoblasts could be classified into 2 subpopulations: low (L), having proresorption properties, and high (H), having proformation properties. The purpose of this study was to investigate the importance of the ephrin system in OA subchondral bone osteoblasts., Methods: The presence of the EphB4 receptor was determined by immunohistochemistry, and its expression level, modulation upon treatment, and consequences of activation by ephrin B2 were determined by quantitative polymerase chain reaction. The effects of ephrin B2 activation of the EphB4 receptor on bone resorption activity were also determined. EphB4 receptor activation signaling pathways were investigated by specific enzyme-linked immunosorbent assay., Results: EphB4 receptors were present in subchondral bone osteoblasts and osteocytes. Compared with normal and H-OA osteoblasts, EphB4 receptor expression levels were significantly increased in L-OA osteoblasts, with no difference between normal and H-OA osteoblasts. EphB4 receptor levels in L-OA osteoblasts were significantly up-regulated by prostaglandin E2 (PGE2) and interleukin-17 (IL-17). Ephrin B2, PGE2, and IL-17 significantly inhibited bone resorption activity in these cells. EphB4 activation by ephrin B2 significantly inhibited the expression of IL-1beta, IL-6, matrix metalloproteinase 1 (MMP-1), MMP-9, MMP-13, and RANKL, but not MMP-2 and osteoprotegerin. EphB4 receptor activation significantly inhibited the phosphatidylinositol 3-kinase/Akt pathway., Conclusion: This study is the first to provide evidence that EphB4 receptor activation by ephrin B2 in OA subchondral bone could affect abnormal metabolism in this tissue by inhibiting resorption factors and their activities. Ephrin B2 could be targeted as a specific therapeutic approach in the development of a disease-modifying OA drug.

Proteinase-activated receptors (PARs) belong to a family of G protein-coupled receptors. PARs are activated by a serine-dependent cleavage generating a tethered activating ligand. PAR-2 was shown to be involved in inflammatory pathways. We investigated the in situ levels and modulation of PAR-2 in human normal and osteoarthritis (OA) cartilage/chondrocytes. Furthermore, we evaluated the role of PAR-2 on the synthesis of the major catabolic factors in OA cartilage, including metalloproteinase (MMP)-1 and MMP-13 and the inflammatory mediator cyclooxygenase 2 (COX-2), as well as the PAR-2-activated signalling pathways in OA chondrocytes. PAR-2 expression was determined using real-time reverse transcription-polymerase chain reaction and protein levels by immunohistochemistry in normal and OA cartilage. Protein modulation was investigated in OA cartilage explants treated with a specific PAR-2-activating peptide (PAR-2-AP), SLIGKV-NH2 (1 to 400 microM), interleukin 1 beta (IL-1beta) (100 pg/mL), tumor necrosis factor-alpha (TNF-alpha) (5 ng/mL), transforming growth factor-beta-1 (TGF-beta1) (10 ng/mL), or the signalling pathway inhibitors of p38 (SB202190), MEK1/2 (mitogen-activated protein kinase kinase) (PD98059), and nuclear factor-kappa B (NF-kappaB) (SN50), and PAR-2 levels were determined by immunohistochemistry. Signalling pathways were analyzed on OA chondrocytes by Western blot using specific phospho-antibodies against extracellular signal-regulated kinase 1/2 (Erk1/2), p38, JNK (c-jun N-terminal kinase), and NF-kappaB in the presence or absence of the PAR-2-AP and/or IL-1beta. PAR-2-induced MMP and COX-2 levels in cartilage were determined by immunohistochemistry. PAR-2 is produced by human chondrocytes and is significantly upregulated in OA compared with normal chondrocytes (p < 0.04 and p < 0.03, respectively). The receptor levels were significantly upregulated by IL-1beta (p < 0.006) and TNF-alpha (p < 0.002) as well as by the PAR-2-AP at 10, 100, and 400 microM (p < 0.02) and were downregulated by the inhibition of p38. After 48 hours of incubation, PAR-2 activation significantly induced MMP-1 and COX-2 starting at 10 microM (both p < 0.005) and MMP-13 at 100 microM (p < 0.02) as well as the phosphorylation of Erk1/2 and p38 within 5 minutes of incubation (p < 0.03). Though not statistically significant, IL-1beta produced an additional effect on the activation of Erk1/2 and p38. This study documents, for the first time, functional consequences of PAR-2 activation in human OA cartilage, identifies p38 as the major signalling pathway regulating its synthesis, and demonstrates that specific PAR-2 activation induces Erk1/2 and p38 in OA chondrocytes. These results suggest PAR-2 as a potential new therapeutic target for the treatment of OA.