Background Osteoarthritis (OA) as well as rheumatoid arthritis (RA) are chronic diseases associated with joint destruction and mobility impairment. Data about changes in immune system in RA and the significant role of T cells, primarily Th17 cells, are now well recognised. On the other hand data about immunological profile in OA are limited, because OA has long been regarded in the past as a non inflammatory disease.
Objectives Our study aim to measure the distribution and the activation degree of CD4+ Tlymphocites and primarily of Th17 in peripheral blood of OA, RA and age-matched healthy controls.
Methods Patients with established diagnosis of RA according to ACR/EULAR 2010 criteria, knee or hipbOA according to ACR criteria and volunteers healthy blood donors were eligible. Other inclusion criteria were: DAS28 between 3.2 and 5.1 or a WOMAC Likert score more than 50 respectively, age between 40 to 60 years old, Kelgren Lawrence index of 2-3. Exclusion criteria were the presence of other autoimmune diseases, tumors or secondary osteoarthritis. Finally no changes in rheumatologic drugs were allowed from 3 months before enrolment. Multi-channel flow cytometry and monoclonal antibodies against CD3, CD4, CD8, CCR6 CD38 CXCR3 and HLA DR were used to distinguish and quantificate T cells subpopulation. Participants were informed about the aim of the project and gave their written consent. The Local Ethic Committee accepted the project.
Results We analysed blood samples of 131 subjects (75 females, 56 males). 55 Patients with well defined RA, 56 with hip or knee OA and 20 healthy controls age matched. Mean age was 45±2.7 years old (p>0.05 between groups). Blood samples from RA patients had significantly higher count of CD4+CD38+DR+ (activated CD4 T cells) and Th17 (CCR6+CXCR3-) cells as compared to OA patients and control group (P<0.01). Furthermore the samples from the OA patients had an higher percentage of activated CD4 T cells and Th17 cells as compared to control group (P<0.05). Interesting there was no difference between Th1 (CD4+CXCR3+CCR6-) and Th2 (CD4+CXCR3-CCR6-) between the three groups (P>0.1)
Conclusions According to the latest view of OA disease pathogenesis, our preliminary results give support to the hypothesis that OA may also be a disease with an immunological/inflammatory involvement like RA. In fact it seems that there is a quantitative but non qualitative difference in Th17 cells profile, including the expression of activation markers, between RA and OA.
Disclosure of Interest None declared
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