Interestingly, the expression of Nrf2 and HO-1 was upregulated by LPS only in young LPS-PD mice, but not in aged mice, suggesting that the upregulation of Nrf2 and HO-1 is associated with the age, independently of TLR2-p-NF-kB/p65 status. Here, TLR2 is linked to Parkinson disease.