Figure 3. Correlation of thermoneutral exosomal miR-92a in serum with BAT activity measured in humans after acute cold exposure.

(a) ¹⁸F-FDG PET/CT image of a subject with high (brown) and low (blue) BAT activity. (b) miR-92a expression as quantified by qPCR. Subjects were separated into two groups with high and low BAT activity. Data is normalized to U6, and expressed as mean±s.e.m. (unpaired, two-tailed t-test, *P<0.05, n=11 per group). (c) Log₁₀ miR-92a value is negatively related to BAT SUVmean value when considering the whole group. The obtained correlation equation is: BAT SUVmean (predicted)=−0.8749 × Log₁₀ miR-92a+3.5227, (Pearson's correlation, R²=0.26, P=0.015, n=22). (d) Log₁₀ miR-92a value is negatively related to BAT SUVmax (Pearson's correlation, R²=0.28, P=0.011, n=22). (e) Log₁₀ miR-92a value is negatively related to BAT glucose uptake rates (Pearson's correlation, R²=0.26, P=0.016, n=22). (f) Changes in miR-92a expression levels (ΔLog₁₀ miR-92a value) tended to correlate with changes in BAT activity (Delta BAT SUVmean value) on a 10-day cold acclimation period (Pearson's correlation, R²=0.29, P=0.11; n=10; and Supplementary Table 3). (g) Log₁₀ miR-92a is elevated in individuals without BAT activity (unpaired, two-tailed t-test, **P=0.01, n=6 for no detectable BAT and n=13 for subjects with detectable BAT). (h) Log₁₀ miR-92a value is negatively related to BAT glucose uptake rates in a second cohort (Pearson's correlation, R²=0.40, P=0.004, n=19).