Reminds me of mucopolysaccharidosis. MPS is caused by a defective enzyme that is supposed to break down mucopolysaccharides for disposal so they accumulate in the lysosomes. The low pH in lysosomes is to unfold and open up proteins so they can be digested by enzymes. The article implies they've yet to figure out what reduces the acidity of neuronal lysosomes. This is a topic well worth keeping an eye on.