Abstract

Background: Bone morphogenetic protein-5 (BMP-5)
has been shown to be essential for nephrogenesis. Its
role in adult kidney and in patients with hypertensive
nephrosclerosis is still unknown.
Methods: BMP-5 expression was evaluated by immunostaining
and real-time PCR in tissue samples from
normal and nephrosclerotic human kidneys. The impact
of transforming growth factor-β (TGF-β), tumor
necrosis factor-α (TNF-α) and angiotensin-II (AT-II) on
expression of BMP-5 and its receptors was quantified
in proximal tubular cells (HK-2). Functional characteristics
of BMP-5 were evaluated by testing its influence
on TGF-β–induced epithelial-to-mesenchymal transition
(EMT), TNF-α–induced apoptosis of HK-2 cells
and inflammatory cell infiltration.
Results: BMP-5 expression was localized in tubular
epithelial cells and significantly decreased in nephrosclerotic
kidneys. Stimulation of HK-2 cells with TGF-β,
TNF-α and AT-II resulted in a significant decreased expression
of BMP-5 and its receptors. BMP-5 attenuated
TGF-β–induced EMT, TNF-α–induced apoptosis
and migration of mononuclear cells.
Conclusions: BMP-5 is expressed in the tubuli of adult
kidneys. Its decreased expression in nephrosclerosis
along with its regenerative capabilities in HK-2 cells
may point to a protective role in hypertensive nephrosclerosis.