IN THE NEWS: FSP-1

 Urinary FSP1 as a possible acute glomerulonephritis biomarker.  Apparently when you have renal injury, it leads to accumulation of fibroblast specific protein 1 (FSP-1) in the kidney and this could serve as a biomarker. A paper in JASN showed that this urinary FSP-1 was elevated significantly more in crescentic GN and later even became undetectable after treatment.  The authors suggest that it could be screening test for active GN.  Interestingly, the same group had found this elevation in diabetic nephropathy as well,  Take a look at the original paper in JASN.  Is it really? or is it a marker of podocyte damage. Take a look at similar paper now using FSGS showing that it might reflect detachment of foot processes. The same authors have shown that this entity is EMT in tubular interstitial fibrosis.  And HIVAN as well.  Is FSP1 measurement as measuring podocyturia? Or are we truly getting to a potential urinary marker?