Galectin-3 has been suggested as a pro-inflammatory mediator in animal arthritis and rheumatoid arthritis (RA). We aimed to study the serum level of galectin-3 in patients with newly diagnosed RA and associations with disease profile, Magnetic resonance imaging (MRI) findings and seromarkers of synovial matrix inflammation. One hundred and sixty DMARD naïve patients newly diagnosed with RA were included (CIMESTRA study). Clinical, serological and imaging data were recorded before treatment and at 6 weeks, 3 and 12 months. Galectin-3 and hyaluronan (HYA) were measured by ELISA (R&D and Corgenix, USA), and the N-terminal propeptide of type III collagen (PIIINP) by radioimmunoassay (Orion Diagnostica, Finland). One hundred and nineteen, 87 and 60 blood donors served as controls for galectin-3, HYA and PIIINP, respectively. Baseline galectin-3 was significantly elevated in anti-CCP positive (4.2 μg/l IQR [3.6;6.1]) patients as compared with anti-CCP negatives (4.0 μg/l [2.6;4.9], P = 0.05) and controls (3.8 μg/l [3.0;4.8], P < 0.01). During treatment, galectin-3 remained elevated, but increased transiently with peak values at 6 weeks. Galectin-3 correlated with baseline smoking, anti-CCP, and with MRI erosion score after 1 year of follow-up. HYA and PIIINP were elevated (P < 0.001) irrespective of anti-CCP status and correlated positively with synovitis assessed clinically and by MRI. HYA and PIIINP did not correlate with galectin-3. These observations indicate that HYA and PIIINP mainly reflect expansive synovitis proliferation while galectin-3 is more closely linked to autoimmunity, smoking and joint destructive processes.

BackgroundUndifferentiated arthritis (UA) is a label applied to patients with joint complaints which cannot be classified according to current criteria, which implies a need for precision diagnostic technologies. We studied serum galectin-3, a proinflammatory mediator, and seromarkers of structural joint elements in patients with early, UA and their associations with disease profile and biochemical and imaging findings.MethodsOne hundred and eleven UA patients were followed-up for at least 12 months and reclassified according to appropriate criteria (TUDAR). At baseline, demographics and laboratory and clinical disease measures, as well as wrist magnetic resonance imaging (MRI) synovitis, erosion, and bone marrow edema scorings, were recorded. Galectin-3, the type IIA collagen N-terminal propeptide (PIIANP), which is a marker of regenerative cartilage formation, and hyaluronan (HYA), which is prevalent in synovial tissue swellings, were measured by enzyme-linked immunosorbent assay (ELISA). Receiver operating characteristic (ROC) curve analysis was carried out to assess the discriminant capacity of galectin-3 against arthritis subsets.ResultsGalectin-3 was increased in pre-rheumatoid arthritis (RA) (4.6 μg/l, interquartile range (IQR) 3.8–5.5) versus non-RA (4.0 μg/l, IQR 3.1–4.9; p = 0.03) and controls (3.8 μg/l, IQR 3.0–4.8; p = 0.009). PIIANP was equally depressed in either subset (p < 0.01). Galectin-3 in non-RA and HYA in UA did not differ from healthy controls. In the entire UA cohort, galectin-3 correlated with the MRI bone marrow edema score, while PIIANP correlated with the MRI erosion score, and HYA with the synovitis and erosion scores. ROC curve analysis showed that baseline galectin-3 discriminated well between pre-RA and non-RA with univariate area under the curve (AUC) of 0.64 (95% confidence interval (CI) 0.53–0.76) while AUC for galectin-3 + anti-CCP increased to 0.71 (95% CI 0.59–0.83).ConclusionsGalectin-3 in serum was increased in patients with early UA of pre-RA origin. Cartilage remodeling assessed by PIIANP was diminished in UA irrespective of subsequent clinical differentiation, while HYA did not differ from controls. ROC analysis showed a potential for galectin-3 to discriminate between pre-RA and non-RA.Trial registrationKF 11 315829. Registered 25 July 2006.

Galectin‐3 has been suggested as a pro‐inflammatory mediator in rheumatoid arthritis (RA). Previous studies have reported overexpression of Galectin‐3 in RA synovitis and increased levels in synovial fluid and serum in long‐standing RA compared with osteoarthritis and healthy controls. Our objectives were to study whether serum Galectin‐3 (1) exhibits circadian variation and/or (2) responds to exercise in RA and controls. The study on circadian patterns (1) comprised eleven patients with newly diagnosed RA, disease duration less than 6 months (ERA), 10 patients with long‐standing RA [5–15 years (LRA)] and 16 self‐reportedly healthy control subjects. During 24 h, 7 blood samples were drawn at 3‐h intervals starting at 10 a.m. through 10 p.m. and at 7 and 10 a.m. on the following day. The study on the effect of physical activity (2) included 10 patients with ERA, 10 with LRA and 14 controls. The participants underwent a standardized exercise programme and four blood samples were drawn before, during and after exercise. Serum Galectin‐3 was quantified by ELISA (R&D systems). (1) Galectin‐3 was increased at baseline in both RA subsets (P = 0.08). There were no diurnal oscillations (P = 0.85). Day‐to‐day variation amounted to 3%. (2) Baseline Galectin‐3 was increased in LRA versus controls and ERA (P < 0.01 and 0.05). Physical exercise induced 10–15% Galectin‐3 increments in RA and controls (P < 0.001) peaking after 1–3 h. To conclude, Galectin‐3 did not exhibit circadian variation. Day‐to‐day variation was 3%. Exercise elicited comparable increments in patients with RA of short and long duration and controls, approaching normal after 1–3 h.

Sorensen FB. Site-specific absence of microfibrillar-associated protein 4 (MFAP4) from the internal elastic membrane of arterioles in the rheumatoid arthritis synovial membrane: an immunohistochemical study in patients with advanced rheumatoid arthritis versus osteoarthritis. APMIS 2019;127:588-593.Microfibrillar-associated protein 4 (MFAP4) is a non-structural matrix protein with cell regulatory activities and a potential as seromarker for fibrosis. We aimed to study the occurrence of MFAP4 in the synovial membrane from patients with rheumatoid arthritis (RA) vs osteoarthritis (OA). Formaldehyde-fixed synovial tissue sections, from patients with RA (N = 6) and OA (N = 6) undergoing total hip arthroplasty, were deparaffinized and immunostained with monoclonal antibodies against MFAP4. Elastin was detected using ElastiKit. MFAP4 in serum (sMFAP4) and synovial fluid was measured by an immunoassay. MFAP4 was present in synovial biopsies from both RA and OA patients, particularly prominent in deep arterioles where it colocalized with elastin. Notably however, MFAP4 was absent from the internal elastic lamina in RA arterioles irrespective of disease duration and synovitis activity, while present although with irregular staining patterns in OA specimens. sMFAP4 was increased in RA and OA serum vs healthy controls: median (interquartile range) 29.8 (25.3-39.1) and 25.5 U/L (18.1-43.3) vs 17.7 U/L (13.7-21.2), p = 0.006 and p = 0.02, respectively The concentration of synovial fluid was lower than in serum in both RA and OA. These findings may suggest that MFAP4 is involved in adaptive vessel wall remodeling associated with chronic joint disease.