TNF and Parkinson disease: Moreover, the RT-qPCR results showed that the relative mRNA expression levels of IL-1β, IL-6, IL-10, TNF-α, iNOS, and COX-2 were increased in MPTP-induced PD mice, whereas pretreatment with crocetin to MPTP-treated mice partially suppressed the expression of proinflammatory cytokines (Figure 2(d)).