Background/Purpose:  The immunomodulatory effects of adipokines have been extensively studied in rheumatic diseases, there is a paucity of information regarding their effects on bone metabolism. Our study aimed to investigate the relationship between changes in serum adipokines levels and radiographic progression in patients with ankylosing spondylitis (AS).

Methods:  Twenty male patients with AS naïve to biologics and 11 age- and gender-matched male healthy subjects were consecutively recruited at a university-affiliated rheumatology center. Serum levels of leptin, adiponectin, resistin, TNF- α, IL-6, and DKK-1 were assessed by enzyme-linked immunosorbent assay at baseline and 2 years later. AS patients underwent lateral cervical and lumbar spine radiography baseline and 2 years later. Radiographic progression was defined as worsening of modified Stoke Ankylosing Spondylitis Spine Score (mSASSS) by ≥ 2 units over the 2 years from baseline.

Results:  Baseline serum leptin and adiponectin levels in AS patients did not differ significantly from those in the controls; however, AS patients had a significantly higher resistin levels (5.5 [3.8-7.7] ng/ml) compared to controls (3.8 [1.9-5.1] ng/ml) at baseline (p=0.049). Baseline serum leptin, adiponectin and resistin levels were not correlated with disease activity, functional, metrological indices or mSASSS. Two years later, a significant increase in serum leptin and resistin levels and mSASSS was observed in AS patients, whereas serum DKK-1 levels significantly decreased. Seven (35%) of the 20 AS patients showed radiographic progression after 2 years. Median changes of serum leptin levels during the 2-year follow-up in AS patients with radiographic progression was significantly higher than in those without this feature (1.6 [0.7-7.1] ng/ml vs -0.2 [-0.6-0.5] ng/ml, p=0.002). In multivariable logistic regression models, the magnitude of changes in serum leptin levels over the 2-year period was significantly associated with radiographic progression in AS patients (OR=8.24, 95% CI=1.1-61.6, p=0.04). Additionally, changes in serum adiponectin, resistin, TNF- α, IL-6 and DKK-1 levels were not related to radiographic progression.

Conclusion: Increase in serum leptin levels over a 2-year period significantly correlated with radiographic progression in AS patients. Our findings suggest that leptin may be involved in the pathogenesis of new bone formation in AS. Table 1. Logistic regression models for the radiographic progression in patients with ankylosing spondylitis

TNF-α; tumor necrosis factor- α, BMI; body mass index ^aEstimated using multivariable logistic regression model with backward selection including changes in leptin levels, age and TNF-α blocker use

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/increase-in-serum-leptin-levels-is-associated-with-radiographic-progression-of-male-patients-with-ankylosing-spondylitis-a-2-year-longitudinal-study/