Epidermal nicotinamide adenine dinucleotides in psoriasis and neurodermatitis (lichen simplex hypertrophicus).
Epidermal nicotinamide adenine dinucleotides were measured in subcorneal and basal epidermal layers in patients with psoriasis and neurodermatitis and in healthy controls. Lowry's microtechniques utilizing enzymatic cycling were used. The total NAD content in these groups was except for the involved psoriatic skin about 1.1 mmoles/kg dry weight. Between 40 and 50% of this content consisted of the reduced form. In the involved psoriatic skin the total NAD content was increased to 1.5 mmoles/kg, this increase being mainly due to a rise in NAD+. There was no difference in NAD content between epidermal layers in the various groups studied. The total NADP content was near 0.15 mmoles/kg in healthy controls and in patients with neurodermatitis. The subcorneal layers contained 10% more of the dinucleotide than the basal layers, but in the two layers the reduced form amounted to about 80% of the total. In both non-involved and involved skin of the psoriatic patients the total NADP content was significantly increased above the control level, by up to 20% in the former and up to 65% in the latter. In the two layers studied the NADP+ content was increased by about 75% in both non-involved and involved areas. In contrast, the NADPH content rose only in the basal layers of the lesion, by 55%. The increased levels of NADP+ and NADPH found in psoriasis might suggest an accelerated or differently conducted NADPH dependent biosynthesis in this disease.