TNF and Parkinson disease: Serum TNF (Fig. 2g) and serum IFNγ (Fig. 2i) were lower in PD subjects compared to HC subjects (F(1,16) = 208.58; p < 0.0001, and F(1,16) = 8.49; p = 0.009, respectively), and serum NGAL (Fig. 2h) was higher in PD compared to HCs (F(1,16) = 25.98; p < 0.0001).