Circulating CD14++CD16+ Monocyte Subsets as a Surrogate Marker of the Therapeutic Effect of Corticosteroid Therapy in Patients With Cardiac Sarcoidosis

Background: We aimed to evaluate whether specific monocyte subsets could serve as surrogate markers of disease activity in cardiac sarcoidosis (CS) evaluated by F-18-fluoro-2-deoxyglucose positron emission tomography (F-18-FDG PET). Methods and Results: We studied 28 patients with CS (8 men; mean age: 61 +/- 9 years) diagnosed according to consensus criteria. We divided the patients into 2 groups: known CS receiving corticosteroid therapy (Rx(+); n=13) and new-onset CS (Rx(-); n=15), and analyzed 3 distinct monocyte subsets (CD14(+)CD16(-), CD14(++) CD16(+), and CD14(+)-CD16(+)). Monocyte subsets were also analyzed in 10 Rx(-) patients before and 12 weeks after starting corticosteroid therapy. Inflammatory activity was quantified by F-18-FDG PET using the coefficient of variation (COV) of the standardized uptake value (SUV). The proportion of CD14(++)CD16(+) monocytes in Rx(+) patients (10.8 [0.2-23.5] %) was significantly lower than in Rx(-) patients (23.0 [11.5-38.4] %, P=0.001). After corticosteroid therapy, the COV of the SUV was significantly improved from 0.32 [0.14-0.62] to 0.17 [0.04-0.43] (P=0.017). The proportion of CD14(++)16(+) monocytes showed a significant decrease from 22.2 [8.8-38.4] % to 8.4 [1.8-16.8] % (P=0.001). The decrease in the proportion of CD14(++)16(+) monocytes significantly correlated with the decrease in the COV of the SUV (r=0.495, P=0.027). Conclusions: CD14(++)16(+) monocytes are a possible surrogate marker of the therapeutic effect of corticosteroid therapy in CS.