The aim of our study was to analyse the serum interleukin-6 (IL-6), tumour necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta) and interferon-gamma (IFN-gamma) levels in patients with AS and their relationship with disease activity. An ELISA test was used to analyse serum cytokine (IL-6, TNF-alpha, IL-1 beta and IFN-gamma) levels in 69 patients with AS. Results were compared with those from 43 patients with RA and 36 patients with non-inflammatory back pain. The relationship between serum concentrations of the different cytokines and parameters of disease activity and severity in AS patients was also evaluated. IL-6 and TNF-alpha serum levels, but not IL-1 beta and IFN-gamma, were significantly higher in AS than in NIBP. However, patients with RA showed higher serum levels of IL-6, TNF-alpha and IFN-gamma than both AS and NIBP patients. In AS, IL-6 correlated with clinical parameters of disease activity with significant correlation being observed with laboratory parameters of inflammation such as ESR, CRP, platelet count and clinical parameters of severity such as vertebral mobility. TNF-alpha did not correlate with laboratory or clinical parameters of activity. Macrophagic cytokines (TNF-alpha and IL-6), are increased in AS patients and IL-6 closely correlated with the activity of the disease.

Synovial LN in RA predicts a lower response to therapy. LN features can be reversed after a short period of anti-TNFalpha therapy in parallel to good clinical responses.

Background: Ectopic lymphoid neogenesis (LN) occurs in rheumatoid synovium, where it is thought to drive local antigen-dependent B cell development and autoantibody production. This process involves the expression of specific homing chemokines and the development of high endothelial venules (HEV). Objective: To investigate whether these mechanisms occur in psoriatic arthritis (PsA) synovium, where autoantibodies have not been described and the organisation and function of B cells is not clear, and to analyse their clinical correlates. Methods: Arthroscopic synovial biopsy specimens from patients with PsA before and after tumour necrosis factor a blockade were characterised by immunohistochemical analysis for T/B cell segregation, peripheral lymph node addressin (PNAd)-positive HEV, and the expression of CXCL13, CCL21 and CXCL12 chemokines in relation to the size of lymphoid aggregates. Results: Lymphoid aggregates of variable sizes were observed in 25 of 27 PsA synovial tissues. T/B cell segregation was often observed, and was correlated with the size of lymphoid aggregates. A close relationship between the presence of large and highly organised aggregates, the development of PNAd+ HEV, and the expression of CXCL13 and CCL21 was found. Large organised aggregates with all LN features were found in 13 of 27 tissues. LN in PsA synovitis was not related to the duration, pattern or severity of the disease. The synovial LN pattern remained stable over time in persistent synovitis, but a complete response to treatment was associated with a regression of the LN features. Conclusions: LN occurs frequently in inflamed PsA synovial tissues. Highly organised follicles display the characteristic features of PNAd+ HEV and CXCL13 and CCL21 expression, demonstrating that the microanatomical bases for germinal centre formation are present in PsA. The regression of LN on effective treatment indicates that the pathogenic and clinical relevance of these structures in PsA merits further investigation.

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