Effect of postprandial lipaemia on plasma complement concentrations in PCOS subjects and controls
To compare the effects of postprandial lipaemia on complement secretion, PCOS subjects and healthy volunteers in cohort 2 underwent an OFTT. As expected, plasma triglyceride levels increased significantly from baseline in both PCOS and control groups (figure 2a), reaching maximum levels (Tmax) at 240 minutes (mean±SEM; 0.86±0.13 mmol/l [baseline] versus 1.6±0.24 mmol/l; p<0.0001) and 180 minutes (mean±SEM; 0.75±0.12 mmol/l [baseline] versus 1.45±0.26 mmol/l; p<0.0001) post-OFTT respectively. No significant differences were observed between groups.
There was a significant difference in the postprandial factor H response between PCOS and control groups (figure 2b and table S5). In controls, factor H levels fell sharply from baseline during the first hour post-OFTT (mean±SEM; 250.9± 21.49 µg/ml versus 173.6±15.26 µg/ml; p<0.0001). In contrast, in the PCOS group, factor H levels increased 30 minutes post-OFTT, although this did not reach significance. Consequently, the AUC for factor H was significantly different between PCOS and controls (table S5). No other differences in complement protein changes in response to OFTT were observed between groups (table S5).
Postprandial TCC levels increased from baseline in both controls and PCOS subjects, although this only reached significance in the latter, where Tmax was reached at 120 minutes post-OFTT (figure 2c) (mean±SEM; 0.26± 0.07 µg/ml [baseline] versus 0.38± 0.06 µg/ml [120 mins]; p<0.0001). Postprandial C3 and C4 levels increased significantly from baseline in both PCOS and control groups, reaching Tmax at 180 minutes post-OFTT (figure 2d and e respectively) (mean±SEM; C3; 1.15±0.04 g/l versus 1.27±0.05 g/l and 1.13±0.05 g/l versus 1.24±0.07 g/l respectively, and C4; 0.21 ± 0.01 g/l versus 0.24 ± 0.02 g/l and 0.21 ± 0.02 g/l versus 0.24 ± 0.02 g/l respectively). There were no significant post-OFTT changes in properdin or C3a(desArg) concentrations in either group (figure 2f and g respectively).