Noninvasive Epidermal Metabolite Profiling

A buffer
placed in brief contact in the skin was assayed by 1H NMR
spectroscopy. We found that this passive extraction
of the skin surface yields abundant metabolites. Metabolites of the
skin surface originate from a variety of sources, including the sweat
gland, which produces lactate from the glucose received from its capillary
bed. Little is known about how metabolites resident on and within
the skin surface respond to a metabolic or hemodynamic perturbation.
As a possible application of epidermal metabolite profiling, we asked
whether metabolites extracted from the skin surface are indicative
of heart failure. The levels of lactate and other molecules were significantly
lower in patients in heart failure than in individuals who reported
healthy heart function, possibly due to reduced blood flow to the
sweat gland resulting in a lack of tissue perfusion. Most amino acids
were unchanged in levels, except for glycine and serine that increased
as a percentage of all amino acids. These results have the potential
in the long term to help decide the extent to which a patient has
heart failure for which objective measures are lacking. Moreover,
the results suggest that epidermal metabolite profiling may be useful
for other assessments of human health.