Dustan HP
Does keloid pathogenesis hold the key to understanding
black/white differences in hypertension severity?
Hypertension
(Dec) 26:858 1995
The incidence of End-Stage Renal Disease attributed to hypertensive
nephrosclerosis in the United States in 1991 was 29% and the ratio of
black/white
patients with this lesion is about 6:1. The reasons for the marked racial
differences in the incidence of ESRD in the United States are
unknown. In this
clinical conference, Dustan points out that progressive renal disease may
occur
despite blood pressure lowering in hypertensive blacks, thus raising the
possibility
that other factors are important in progression of renal disease.
Keloids, benign
tumors of the skin or cornea, occur much more frequently in blacks as
compared
to whites and recent evidence suggests that growth factors including
transforming
growth factor beta (TGF-B) and platelet-derived growth factor (PDGF) play an
important role in the pathogenesis of keloids. Dustan hypothesizes that
differences in the production or action of these cytokines which are known
growth
factors for both fibroblasts and vascular smooth muscle cells may be one
reason
for the racial differences in ESRD. Blacks with hypertensive
nephrosclerosis
exhibit changes in blood vessels which resemble atherosclerosis:
hypertrophy,
increased extracellular matrix, increased collagen and luminal narrowing.
In
relation to this process she points out that cytokines, in particular TGF-B
may play
an important role in the pathogenesis of glomerulosclerosis in hypertension
as has
been shown for patients with glomerulonephritides. She suggest the renal
vasculature of blacks may be more susceptible to the effects of hypertension
because of differences in the response of renal cells to growth
factors inlcuding
TGF-B and PDGF.
The hypothesis is very reasonable considering that we are still
uncertain as to whether blood pressure lowering per se can prevent
progressive
renal disease in patients with established renal insufficiency caused by
hypertension. Both basic and clinical studies aimed at better understanding
of the
pathogenesis of the renal disease and its treatment in relation to these and
other
growth factors is an important priority in
nephrology.
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H: Special problems :
Ethnic populations