Association of systemic and intra-articular osteoclastogenic potential, pro-inflammatory mediators and disease activity with the form of inflammatory arthritis.

PURPOSE: We aimed to assess osteoclastogenic potential of peripheral blood mononuclear cells (PBMC) and synovial fluid-derived mononuclear cells (SFMC) in different forms of arthritis and to correlate it with inflammatory mediators within intra-articular and circulatory compartments. METHODS: Paired PBMC and SFMC samples of patients with rheumatoid arthritis (RA; n = 10) and psoriatic arthritis (PsA; n = 10), and PBMC of healthy controls were cultured to assess osteoclastogenic potential by the number of tartrate-resistant acid phosphatase (TRAP)-positive osteoclasts (OCs) and expression of OC-related genes (receptor activator of nuclear factor-κΒ (RANK), cFMS, and TRAP). Osteoclastogenesis was correlated with the arthritis-related inflammatory indicators in serum and synovial fluid (SF). RESULTS: Number of OCs differentiated from PBMC was significantly higher in RA and PsA compared with control, with RA having more OCs compared with PsA. There was no difference in SFMC OC number between arthritic patients, but RANK expression in OCs differentiated from SFMC was higher in PsA compared with RA. SF of PsA patients more potently induced OC differentiation from control CD3(-)CD19(-)CD56(-)CD11b(+)CD115(+) PBMC compared with RA, paralleled with higher RANK-ligand expression in PsA SFMC. Positive correlations of OC number with erythrocyte sedimentation rate, serum level of CCL2, and PBMC gene expression of interleukin-18 and Fas-ligand were observed. CONCLUSION: Osteoclastogenic potential is systemically enhanced in patients with RA, paralleled by disordered systemic and local expression of proinflammatory mediators, whereas PsA involves specific deregulation in RANKL/RANK axis. Our study reveals arthritis-specific mediators associated with the form of arthritis, indicating clinical relevance for diagnosis and treatment.

Osteoblastogenesis from synovial fluid-derived cells is related to the type and severity of juvenile idiopathic arthritis.

INTRODUCTION: Juvenile idiopathic arthritis (JIA) is characterized by synovial inflammation, followed by hyperplastic changes of the synovium, and destruction of articular cartilage along with underlying bone. This hyperplastic process is the result of inflammation-induced activation of NF-κB, which may be accompanied by decreased osteogenic differentiation of synovial mesenchymal progenitors and contribute to bone resorption. We aimed to explore osteoblast differentiation of synovial fluid (SF)-derived mesenchymal progenitors and correlate it with intensity of inflammation in patients with JIA. METHODS: Peripheral blood from 18 patients with oligoarticular (o)JIA, 22 patients with polyarticular (p)JIA and 18 controls was collected along with SF from 18 patients with oJIA and 9 patients with pJIA. SF-derived cells were cultured to assess osteoblastogenesis, using alkaline phosphatase histochemical staining and colorimetric activity assay. The expression of osteoblast-related genes, Runt-related transcription factor 2 (Runx2), Osteoprotegerin (OPG), Receptor activator of nuclear factor κB ligand (RANKL) and arthritis-related cytokine/chemokine genes, Tumor necrosis factor alpha (TNF-α, Fas, Fas ligand (FasL), Interleukin (IL)-1ß, IL-4, IL-6, IL-17, IL-18, CC chemokine ligand (CCL)-2, CCL3, CCL4 was evaluated. Osteoblastogenesis was correlated with systemic and local inflammatory indicators. Expression of osteoblast genes was also analyzed in peripheral blood mononuclear cells (PBMC) and total SF-derived cells from patients with JIA. Additionally, we assessed the inhibitory effect of SF from patients with JIA on differentiation of human bone marrow (hBM)-derived osteoblasts. RESULTS: Osteoblastogenesis from SF-derived progenitors was decreased in patients with pJIA compared to those with oJIA. Osteoblastogenesis from primary SF-derived cells negatively correlated with erythrocyte sedimentation rate (ρ = -0.391, P = 0.05), C-reactive protein concentration (ρ = -0.527, P<0.01) and synovial concentration of IL-17 (ρ = -0.552, P = 0.01). SF-derived osteoblasts from pJIA patients expressed more CCL2 and CCL3 genes than in oJIA (P = 0.04 and P = 0.03, respectively; Mann-Whitney test). Expression of Fas was significantly higher in osteoblasts from patients with pJIA than those with oJIA (P = 0.03, Mann-Whitney test). SF-derived cells from patients with pJIA expressed higher levels of RANKL than in oJIA (P = 0.05, Mann-Whitney test). PBMCs from patients with JIA expressed less OPG than healthy control patients (P = 0.05, Kruskal-Wallis test). SF from all tested JIA patients inhibited differentiation of hBM-derived osteoblasts (P = 0.04, Kruskal-Wallis test). CONCLUSIONS: Osteoblast differentiation was decreased in patients with severe forms of JIA and accompanied by altered cytokine/chemokine expression pattern. Development of therapeutic interventions targeting synovial mesenchymal or osteoblast lineage cells in JIA would contribute to alleviating both bone destruction and inflammation in severe forms of the disease.

Retention of basic sciences knowledge at clinical years of medical curriculum.

AIM: To explore the association between the knowledge of basic (physiology and biochemistry) and clinical sciences (internal medicine) among medical students, and determine the level of retained basic science knowledge at the fifth year of medical studies. METHODS: Medical students attending the second (n=145, response rate 60%) or the fifth year (n=176, response rate 73%) of medical studies at the Zagreb University School of Medicine in Croatia were given an anonymous knowledge test with 15 pairs of questions developed specifically for this purpose. Each pair consisted of a basic and clinical question, with the correct answer to the basic question explaining the physiological or biochemical background of the clinical question. Three pairs of questions were excludes from the analysis due to poor psychometric characteristics. RESULTS: We found statistically significant correlation between basic and clinical tests scores for both groups of students (r=0.47, P<0.001 for the second year and r=0.45, P<0.001 for the fifth year). 2x2 within-between measures ANOVA revealed a significant interaction effect for knowledge test and study year (Wilks lambda=0.55, F(1, 319)=262.7, P<0.001; effect size=0.45), showing that fifth year students scored lower on the basic test than second year students but obtained higher scores on the clinical test. CONCLUSION: The core basic science knowledge is lost during the clinical years of medical studies. Although remembering and understanding basic science concepts as a background of clinical statements at the clinical years does not directly affect clinical knowledge, there is a positive correlation between retained basic science concepts and clinical knowledge.