Fig.1.

Progression of Parkinson’s disease (PD). Gut microflora and Helicobacter pylori may produce toxins and metabolites and trigger an immune response that features cytokines and autoantibodies. The gut microbiome may become dysregulated. Reactive oxygen species may also contribute to the pathogenesis of PD. Collectively this may lead to GI symptoms and altered L-dopa absorption in PD patients taking L-dopa medication, reducing effectiveness of the medication. The GI symptoms and inflammatory process may become systemic to compromise the BBB, eliciting neuroinflammation in the brain. Alpha synuclein aggregation, which is observed both in the gut and brain, leads to the spreading of neuropathology. The loss of dopaminergic neurons in the substantial nigra pars compacta (SNpc) manifests as motor symptoms observed in PD patients. Thus, eradication of H. pylori or return of the gut microflora to the proper balance may ameliorate gut symptoms, L-dopa absorption and motor functions in PD patients, which could delay PD disease progression. Str, Striatum.