FDG-PET provides information about vascular inflammation that is complementary to, and distinct from, clinical assessment in LVV. FDG-PET scan activity during clinical remission was associated with future clinical relapse.

Objective To understand whether directly-measured psoriasis severity is associated with vascular inflammation assessed by 18F-fluorodeoxyglucose positron emission tomography computed tomography (FDG PET/CT). Approach In depth cardiovascular and metabolic phenotyping was performed in adult psoriasis patients (n=60) and controls (n=20). Psoriasis severity was measured using psoriasis area severity index (PASI). Vascular inflammation was measured using average aortic target-to-background ratio using FDG PET/CT. Results Both the psoriasis patients (28 men, 32 women, mean age 47 years) and controls (13 men, 7 women, mean age 41 years) were young with low cardiovascular risk. PASI scores (Median 5.4; IQR 2.8-8.3) were consistent with mild to moderate skin disease severity. Increasing PASI score was associated with an increase in aortic TBR (β=0.41, p=0.001), an association that changed little after adjustment for age, sex and Framingham risk score. We observed evidence of increased neutrophil frequency (mean psoriasis: 3.7±1.2; vs 2.9±1.2; p=0.02) and activation by lower neutrophil surface CD16 and CD62L in blood. Serum levels of S100A8/A9 (745.1±53.3 vs 195.4±157.8 ng/mL; p<0.01) and neutrophil elastase-1 (43.0±2.4 vs 30.8±6.7 ng/mL; p<0.001) were elevated in psoriasis. Finally, S100A8/A9 protein related to both psoriasis skin disease severity (β=0.53; p=0.02) and vascular inflammation (β=0.48; p=0.02). Conclusions Psoriasis severity is associated with vascular inflammation beyond cardiovascular risk factors. Psoriasis increased neutrophil activation and neutrophil markers, and S100A8/A9 related to both skin disease severity and vascular inflammation.