Background/Purpose: Patients with PsA have both increased risk of subclinical atherosclerosis and lower cortical volumetric BMD (vBMD) compared with the general population, probably as a result of the dysregulated molecular pathways. We have reported that inflammation induced by the IL-33/ST2 axis was associated with carotid plaque progression in RA. Emerging data suggest that this axis may also be involved in bone homeostasis and osteoclastogenesis. In this study, we studied the association among IL-33/ST2 pathway, carotid plaque, and vBMD/bone microstructure in PsA patients.

Methods: 80 PsA patients (44 males; 53±10 years) without unstable cardiovascular diseases (CVD) or disorders that could affect bone metabolism were included. Carotid plaque was determined by ultrasound. vBMD and microstructure of the distal radius were measured using high-resolution peripheral quantitative CT (HR-pQCT). Plasma IL-33 and its decoy receptor soluble ST2 (sST2) levels were determined by ELISA.

Results: Plasma sST2 levels were significantly higher in 33 (41%) patients with carotid plaques (11.2±4.5 vs 7.7±3.7 ng/ml, p<0.001). The patients with plaques were also older (57±9 vs 50±10 years, p=0.002), had longer PsA duration (17±7 vs 12±7 years, p=0.006), and an increased prevalence of high CVD risk (Framingham 10-year CVD risk >10%: 64% vs 34%, p=0.013). The prevalence of hyperlipidemia was higher (36% vs 19%, p=0.085) and more patients were put on statins (27% vs 11%, p=0.046). After adjusting for these confounding factors, sST2 was an independent explanatory variable associated with the presence of carotid plaques (odds ratio: 1.3, 95% confidence interval [CI]: [1.2, 1.5]; p=0.003). Using linear regression, plasma sST2 level was negatively associated with cortical vBMD (coefficients: -5.4, 95%CI: [-8.6, -2.3], p=0.001), and positively associated with cortical porosity index (0.25, [0.12, 0.38], p<0.001) and cortical pore volume (3.0, [1.4, 4.6], p<0.001). The associations remained significant after adjusting for confounding factors¹(Table 1). On the other hand, plasma IL-33 levels were not associated with the presence of carotid plaque or vBMD/microstructure.

Conclusion: Plasma sST2 levels are independently associated with both carotid plaque and compromised cortical vBMD/microstructure in PsA patients, indicating that IL-33/ST2 axis may contribute to both atherosclerosis and bone loss. The detailed mechanism should be further investigated.

1. Zhu TY, et al. Osteoporos Int. 2015;26:261-72.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/plasma-soluble-st2-levels-are-independently-associated-with-both-carotid-atherosclerosis-and-compromised-cortical-volumetric-bone-mineral-density-and-microstructure-in-patients-with-psoriatic-arthriti/