Fig. 2
Serum and CSF profiles differ between PD and HC subjects and show distinct diurnal fluctuations. The top diagram summarizes significant results. When sampled across a 26-h period, protein levels of CSF TNF (a), and serum IL-6 (b) fluctuate significantly across the day (F (10,154) = 4.66; p < 0.00001, and F (10,160) = 3.12; p < 0.00001, respectively). CSF IL-8 (c), α-synuclein (d), Aβ40 (e), and Aβ42 (f) are decreased in PD as compared to age-matched HC (F (1,16) = 5.08; p = 0.04, F (1,16) = 8.35 p = 0.01, F (1,16) = 14.69; p = 0.001, and F (1,16) = 4.61; p = 0.05, respectively), and vary across the day (F (10,154) = 2.23; p = 0.01, F (10,160) = 3.30; p < 0.001, F (10,160) = 4.11; p < 0.0001, and F (10,160) = 2.15; p = 0.02, respectively). Serum TNF (g) and serum IFNγ (i) are decreased in PD subjects compared to HC subjects (F (1,16) = 208.58; p < 0.00001 and F (1,16) = 8.49; p = 0.009, respectively), and serum NGAL (h) is increased in PD compared to HC subjects (F (1,16) = 25.98; p < 0.00001). When measured at baseline (time 0 = 5:30 AM), serum TNF (g) was significantly lower in PD subjects as compared with HC subjects (U (83, 88) = 10; p = 0.014), and serum NGAL (h) was significantly higher in PD subjects as compared with HC subjects (U (31, 140) = 10; p = 0.014). There were no differences between PD and HC in any other analyte (see Table 2 for all data). *Indicates significant change in time, and + indicates significant difference between PD and HC. *** and +++ indicate p < 0.0001, ** and ++ indicate p < 0.01, * and + indicate p ≤ 0.05, and ^ indicates a significant difference between PD and HC at time 0; p < 0.05. Superscript numbers indicate the sampling hour where significant changes occur