Parkinson's is caused by lowered dopamine levels, dopamine that is produced in the substantia nigra. In studies with Parkinson's disease CCR5 inhibition lowers inflammation of the substantia nigra allowing dopamine levels to return to normal.

In the article CTMedic cited they propose inflammation of the substantia nigra is the cause of fatigue in MS. Leronlimab would fix that.

https://pubmed.ncbi.nlm.nih.gov/31043478/