Citrullinated and carbamylated proteins in extracellular microvesicles from plasma of patients with rheumatoid arthritis.

OBJECTIVES: To investigate the expression of citrullinated and carbamylated proteins in extracellular microvesicles (EMVs) from RA patients. METHODS: We enrolled 24 RA naïve for biological therapy and 20 healthy donors (HD), matched for age and sex. For each patient, laboratory and clinical data were recorded and clinical indexes were measured (Clinical Disease Activity Index, Simplified Disease Activity Index, DAS28). EMVs in RA patients and HD were purified from plasma and measured by nanoparticle tracking analysis (NanoSight). Further, EMVs were incubated with anti-citrullinated/carbamylated proteins antibodies and processed by flow cytometry and western blot to evaluate the expression of citrullinated/carbamylated antigens. RESULTS: NanoSight revealed a significant increase of EMVs in RA compared with HD. Moreover, cytofluorimetric analysis showed a significative higher expression of citrullinated antigens on EMVs' surface in RA than donors, while no substantial difference was found in the expression of carbamylated antigens. These data were confirmed by western blot which identified vimentin, glycolytic enzyme alpha-enolase 1 and collagen type II as the main citrullinated and carbamylated proteins carried by EMVs. Finally, a relevant correlation between the expression of citrullinated antigens and disease activity was found. CONCLUSIONS: The results of this study suggest an involvement of EMVs in the pathogenesis of RA by inducing autoimmunity.

Belimumab is Able to Induce a Significant Improvement of Joint Activity Status in Patients Diagnosed with Systemic Lupus Erythematosus: Results From a 12-Month Longitudinal Study.

BACKGROUND: Belimumab was the first biological drug approved for the treatment of systemic lupus erythematosus (SLE) patients. Phase II/III randomized controlled trials and real-life studies identified patients with musculoskeletal involvement as best responders. OBJECTIVES: To evaluate the effectiveness of belimumab in SLE-related joint involvement. METHODS: The cohort comprised SLE patients receiving belimumab for musculoskeletal indications. Belimumab was intravenously administrated according to protocols; all the patients were evaluated at baseline (T0) and after 3 (T1), 6 (T2), and 12 (T3) months. We assessed joint activity by disease activity score 28, simple disease activity index (SDAI), clinical disease activity index (CDAI), and swollen tender ratio. Each patient underwent musculoskeletal ultrasound of 34 joints to assess synovial effusion synovial hypertrophy, and power Doppler; by using a semi-quantitative scale (0-3) we obtained the total inflammatory score (0-216). RESULTS: We evaluated 20 patients (males/females 1/19, median age 45 years [interquartile range (IQR) 12], median disease duration 144 months [IQR 144]). CDAI and SDAI significantly decreased at T1 (P = 0.02 and P = 0.01 respectively) and this improvement was maintained at the following time-points (CDAI: T2 P = 0.008, T3 P = 0.004; SDAI: T2 P = 0.006, T3 P = 0.01). A significant reduction of median ultrasound score was identified at T1 (T0 20.5 [IQR 13.5] vs. T1 7.5 [IQR 4.7], P < 0.001), and maintained at T2 (7.0 [IQR 5], P < 0.0001), and T3 (7.0 [IQR 9.0], P < 0.0001). CONCLUSIONS: Belimumab induces a sustained improvement of ultrasound-detected inflammatory status at the articular level.

Anti-LL37 Antibodies Are Present in Psoriatic Arthritis (PsA) Patients: New Biomarkers in PsA.

Psoriatic arthritis (PsA) is a chronic inflammatory arthritis associated with psoriasis. A third of psoriatic patients develop PsA via unknown mechanisms. No reliable diagnostic markers are available for PsA, or prognostic biomarkers for PsA development in psoriasis. We previously uncovered a pro-inflammatory role for cathelicidin LL37 in lesional psoriasis skin. LL37 binds nucleic acids and stimulates plasmacytoid/myeloid dendritic cells (pDC, mDCs) to secrete type I interferon (IFN-I) and pro-inflammatory factors. LL37 becomes an autoantigen for psoriatic Th1-Th17/CD8 T cells. Anti-LL37 antibodies were detected in systemic lupus erythematosus, an autoimmune disease characterized by neutrophil-extracellular-traps release (NETosis) in target organs. LL37 can be substrate of irreversible post-translational modifications, citrullination or carbamylation, linked to neutrophil activity. Here we analyzed inflammatory factors, included LL37, in PsA and psoriasis plasma and PsA synovial fluids (SF)/biopsies. We show that LL37 (as a product of infiltrating neutrophils) and autoantibodies to LL37 are elevated in PsA, but not OA SF. Anti-LL37 antibodies correlate with clinical inflammatory markers. Anti-carbamylated/citrullinated-LL37 antibodies are present in PsA SF/plasma and, at lower extent, in psoriasis plasma, but not in controls. Plasma anti-carbamylated-LL37 antibodies correlate with PsA (DAS44) but not psoriasis (PASI) disease activity. Ectopic lymphoid structures, and deposition of immunoglobulin-(Ig)G-complexes (IC) co-localizing with infiltrating neutrophils, are observed in PsA and not OA synovial tissues (ST). Activated complement (C5a, C9), GM-CSF and IFN-I are up-regulated in PsA and not OA synovia and in PsA and psoriasis plasma but not in HD. C9 and GM-CSF levels in PsA SF correlate with clinical inflammatory markers and DAS44 (C9) and with anti-carbamylated/citrullinated-LL37 antibodies (GM-CSF and IFN-I). Thus, we uncover a role for LL37 as a novel PsA autoantibody target and correlation studies suggest participation of anti-LL37 antibodies to PsA pathogenesis. Notably, plasma antibodies to carbamylated-LL37, which correlate with DAS44, suggest their use as new disease activity markers. GM-CSF and complement C5a and C9 elevation may be responsible for autoantigens release by neutrophils and their modification, fueling inflammation and autoreactivity establishment. Finally, targeting GM-CSF, C5a, C9 can be beneficial in PsA.

Ultrasound evaluation of hand, wrist and foot joint synovitis in systemic lupus erythematosus.

OBJECTIVES: To assess the prevalence and severity of inflammatory abnormalities of the hand, wrist and foot joints in SLE patients by US and to correlate them with clinical, laboratory and disease activity score parameters. METHODS: Sixty-two consecutive SLE patients were enrolled in the present study and underwent clinical evaluation, laboratory tests and bilateral high-resolution US of the hand, wrist and foot joints. Joint effusion (JE), synovial hypertrophy (SH) and local pathological vascularization [power Doppler (PD)] were evaluated according to both a dichotomous score and a semi-quantitative (0-3) grading system. In addition, a global US score was calculated by summing the values given to each elementary lesion for every single joint and every joint group. US findings were correlated with physical examination, serological parameters (CRP, ANA, anti-dsDNA, ENA, aPL, C3 and C4 serum levels) and disease activity indexes (SLEDAI-2K, ECLAM). RESULTS: US detected inflammatory joint abnormalities in 54/62 patients (87.1%); 72.6% presented involvement of the MTP joints, 46.7% the MCP joints, 19.3% the PIP joints and 53% the wrists. A total of 1984 joints were examined highlighting JE in 19.1% of cases, SH in 6.9% and positive PD in 1.1%. The global US inflammatory score had a mean value of 10.9 (s.d. 15.2). No correlations were found between US findings and SLE disease activity parameters. CONCLUSION: US demonstrated a high prevalence of inflammatory joint abnormalities in SLE that were also present in asymptomatic patients. Interestingly, the foot joints were the most frequently involved. US is a valuable tool for detecting subclinical synovitis in SLE.

Rituximab infusion-related adverse event rates are lower in patients with systemic lupus erythematosus than in those with rheumatoid arthritis.

OBJECTIVES: Rituximab (RTX) is a therapeutic option for patients with SLE or RA. We conducted a prospective, longitudinal, observational study to compare rates of RTX-related adverse events (AEs) in these two patient groups. METHODS: RTX was used in 23 patients with SLE that was refractory to conventional therapy and in 31 patients with RA that had been unsuccessfully treated with TNF-α inhibitors. Infusion-related and infectious AE rates were calculated for each group. RESULTS: Seven (22.5%) RA patients experienced an infusion-related reaction. These AEs involved 7/91 (7.7%) infusions administered in the RA group. None of the 102 infusions administered to SLE patients was associated with infusion-related AEs (P = 0.038 vs RA group). The mean daily glucocorticoid dose administered during the week preceding RTX treatment in the SLE group was higher than that for the RA group [0.25 (0.2) vs 0.18 (0.14) mg/kg, P = not significant] and significantly higher than that received by the subgroup of the seven RA patients who experienced infusion-related AEs [0.10 (0.02) mg/kg; P = 0.0017]. Infectious AE rates were also lower (but not significantly so) in the SLE group (8.7 vs 12.9% in RA). CONCLUSIONS: Repeated cycles of RTX in combination with different immunosuppressants is a safe therapeutic option for SLE and RA patients. The lower incidence of infusion-related AEs in the SLE patients might reflect the higher dosage glucocorticoid therapy they received during the week before RTX infusion.