New pro-inflammatory cytokine IL-40 is produced by activated neutrophils and plays a role in the early stages of seropositive rheumatoid arthritis.

OBJECTIVE: Interleukin (IL)-40 is a new cytokine related to immune system function and malignancies. Recently, an association of IL-40 with rheumatoid arthritis (RA) and externalisation of neutrophil extracellular traps (NETosis) was found. As neutrophils are implicated in RA development, we investigated IL-40 in early stages of RA (ERA). METHODS: IL-40 was determined in serum of treatment naïve patients with ERA at baseline (n=60) and 3 months after initiation of conventional therapy and in healthy controls (HC; n=60). Levels of IL-40, cytokines and NETosis markers were measured by ELISA. NETosis was visualised by immunofluorescence. In vitro experiments were performed on peripheral blood neutrophils from ERA patients (n=14). Cell-free DNA was analysed in serum and supernatants. RESULTS: Serum IL-40 was elevated in ERA compared with HC (p<0.0001) and normalised after 3 months of therapy (p<0.0001). Baseline serum IL-40 correlated with rheumatoid factor (IgM) (p<0.01), anti-cyclic citrullinated peptide (p<0.01) autoantibodies and NETosis markers (proteinase 3; neutrophil elastase (NE); myeloperoxidase) (p<0.0001). Levels of NE significantly decreased after therapy (p<0.01) and correlated with the decrease of serum IL-40 (p<0.05). In vitro, neutrophils enhanced IL-40 secretion following NETosis induction (p<0.001) or after exposure to IL-1ß, IL-8 (p<0.05), tumour necrosis factor or lipopolysaccharide (p<0.01). Recombinant IL-40 up-regulated IL-1ß, IL-6 and IL-8 (p<0.05 for all) in vitro. CONCLUSION: We showed that IL-40 is significantly up-regulated in seropositive ERA and decreases after conventional therapy. Moreover, neutrophils are an important source of IL-40 in RA, and its release is potentiated by cytokines and NETosis. Thus, IL-40 may play a role in ERA.

Chemokine and Cytokine Profiles in Patients with Hand Osteoarthritis.

BACKGROUND: The development of hand osteoarthritis (HOA) and its progression into the erosive subset are unclear, but inflammation is suspected to be the main source. To verify the involvement of inflammation in HOA pathogenesis, we evaluate serum inflammatory mediators and their association with HOA-related clinical features in patients. METHODS: 153 participants (50 non-erosive HOA patients, 54 erosive HOA patients, and 49 healthy control subjects) were included in this study. All patients underwent clinical examination, which included assessment of tender and swollen small hand joints, ultrasound (US) examination, and self-reported measures (e.g., AUSCAN or algofunctional indexes). Serum inflammatory mediators were quantified using human cytokine 27-plex immunoassay. We employed linear modelling, correlation analysis, and resampling statistics to evaluate the association of these mediators to HOA. RESULTS: We identified increased levels of nine inflammatory mediators (e.g., eotaxin, monocyte chemoattractant protein 1, interleukin-8, and tumour necrosis factor) in HOA patients compared to healthy controls. Increased mediators correlated with ultrasound findings as well as with clinically tender and swollen joint counts in patients with erosive HOA. However, none of the mediators distinguished between erosive and non-erosive HOA subtypes. CONCLUSION: Our findings support the hypothesis on the involvement of inflammation in HOA.

Serum Calprotectin Discriminates Subclinical Disease Activity from Ultrasound-Defined Remission in Patients with Rheumatoid Arthritis in Clinical Remission.

OBJECTIVE: Clinical remission in some patients with rheumatoid arthritis (RA) may be associated with ongoing synovial inflammation that is not always detectable on clinical examination or reflected by laboratory tests but can be visualized by musculoskeletal ultrasound. The goal of our study was to determine the levels of serum calprotectin, a major leukocyte protein, in patients with RA in clinical remission and to investigate the ability of serum calprotectin levels to distinguish patients in ultrasound-defined remission from those with residual ultrasound subclinical inflammation. METHODS: Seventy RA patients in clinical remission underwent clinical and ultrasound examination. Ultrasound examination was performed according to the German US7 score. Ultrasound remission was defined as grey scale (GS) range 0-1 and power Doppler (PD) range 0. The levels of serum calprotectin and C-reactive protein (CRP) were determined. The discriminatory capacity of calprotectin and CRP in detecting residual ultrasound inflammation was assessed using ROC curves. RESULTS: The total number of patients fulfilling the DAS28-ESR, DAS28-CRP, SDAI and CDAI remission criteria was 58, 67, 32 and 31, respectively. Residual synovial inflammation was found in 58-67% of the patients who fulfilled at least one set of clinical remission criteria. Calprotectin levels were significantly higher in patients with residual synovial inflammation than in those with ultrasound-defined remission (mean 2.5±1.3 vs. 1.7±0.8 µg/mL, p<0.005). Using ultrasound-defined remission criteria, calprotectin had an AUC of 0.692, p<0.05 using DAS28-ESR remission criteria and an AUC of 0.712, p<0.005 using DAS28-CRP remission criteria. Calprotectin correctly distinguished ultrasound remission from subclinical activity in 70% of patients. CRP (AUC DAS28-ESR = 0.494, p = NS; AUC DAS28-CRP = 0.498, p = NS) had lower and insignificant discriminatory capacity. CONCLUSION: The present study demonstrates the potential of calprotectin to distinguish RA patients in both clinical and ultrasound-defined remission from patients in clinical remission but with residual subclinical disease activity.