Elevated gpNMB in type 1 Gaucher disease patients

Gaucher disease (GD) is characterized by the presence of glucosylceramide-laden macrophages (Gaucher cells) as the result of deficiency in the lysosomal hydrolase glucocerebrosidase (GBA). Non-neuronopathic type 1 GD is effectively treated by infusions with macrophage-targeted recombinant glucocerebrosidase. We here report how LC-MSE analysis of the proteome of laser-dissected splenic Gaucher cells revealed high expression of several proteins amongst which was gpNMB. This was confirmed by histochemistry and RNA quantification. Macrophages produce gpNMB as membrane protein but release soluble fragments. In plasma of symptomatic Gaucher patients (n=59) soluble gpNMB was next found to be on average 25-fold increased prior to treatment, without overlap with control values, (control mean: 20 ng/ml; range 11-34 ng/ml vs. GD mean: 495 ng/ml; range: 137-1283 ng/ml).