¹IfADo – Leibniz Research Centre for Working Environment and Human Factors, Dortmund
²Rheumazentrum Ruhrgebiet Herne, Herne

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Introduction: Female and male axial Spondyloarthritis (axSpA) patients show differently pronounced disease progression, treatment outcomes, and biomarker levels, suggesting that there are sex-specific differences in the pathophysiology of axSpA. Nevertheless, knowledge of sex-specific differences in axSpA pathology is still limited and treatment response is worse in female patients. The aim of this study is therefore to delineate sex-specific differences in axSpA-related biomarkers and peripheral blood mononuclear cell (PBMC) subsets in biologically naïve non-radiologic (nr-axSpA) and radiologic axSpA (r-axSpA) patients.

Methods: Plasma samples from biologically naïve nr-axSpA (males n=9–23, females n=5–10), r-axSpA (males n=10–28, females n=4–7) and healthy controls (males n=9–13, females n=9–19) were analyzed for levels of interleukin (IL-)17A, tumor necrosis factor (TNF), IL-6 and leptin by multiplex analysis. PBMC subsets were investigated by flow cytometry utilizing specific extracellular markers.

Results: The average age of the nr-axSpA males was 35 years and of r-axSpA 40 years, whereas nr-axSpA females were in average 41 years and r-axSpA 44 years. Mean disease duration was in nr-axSpA males two years, in r-axSpA 6 years and in nr-axSpA females one year and in r-axSpA 7 years. Healthy control subjects were age and sex matched. TNF was significantly higher in r-axSpA females compared to males (p<0,0005). Leptin was higher in female axSpA compared to healthy controls and male axSpA (p<0,005–0,0001). On the contrary, levels of IL-6 were significantly higher in nr-axSpA males compared to healthy subjects (p<0,05), whereas females showed same levels in all three groups. IL-17A was not detectable in most of the samples with the method used. No significant differences in PBMC subpopulation were observed so far, thus suggesting differences between the local and the systemic inflammation.

Conclusion: Plasma expression of inflammatory markers was different in male and female axSpA patients, which demonstrates the importance and clinical relevance of sex-specific analysis to understand disease pathophysiology. Furthermore, to better interpret the results, cohorts should be analyzed based on sex, radiographic stage (r-axSpA vs nr-axSpA) and disease duration. Such studies will help understanding the pathophysiology of axSpA and to identify sex-specific therapeutic targets to improve personalized treatment response.

Disclosures: Nothing to disclose.