Mobilisation of neutrophils and premature photoaging in chronic vitiligenous skin of black skinned patients

Exposure of white skin (skin phototype I-III) to erythemogenic doses of solar
simulating radiation (SSR) results in an influx of neutrophils. We have
previously shown that neutrophils are a major source of enzymatically active
photoaging-associated proteolytic enzymes. By this capacity they appear to be
important contributors to the process of photoaging of the skin. Furthermore we
have shown that neutrophils infiltrating the epidermis are a source of IL-10, a
cytokine which has been associated with photo-carcinogenesis.
Black skin (skin phototype VI) is better protected against the damaging effects
of solar radiation. Black skin is thus less susceptible to photocarcinogenesis
and photoaging. This is most likely due to abundant melanin pigment present in
the epidermis of black skin. We have shown that exposing white and black
skinned persons to equal physical doses of SSR induces a strong neutrophilic
infiltrate in white but not in black skin. Furthermore DNA photoproducts
following exposure to SSR are limited to the suprabasal epidermis in black skin
while they are distributed throughout the epidermis and upper dermis in white
skin. These findings support the hypothesis that melanin plays a major role in
the protection of skin against the deleterious effects of solar radiation.
Vitiligo is a skin disease in which melanocytes disappear from the skin and as
a consequence the production of melanin is halted. Literature shows
conflicting data on the susceptibility of vitiligenous skin to photoaging and
photo-carcinogenesis.

To further investigate the photoprotective properties of melanin and the role
of skin-infiltrating neutrophils with respect to the damaging effects of solar
radiation on human skin.

Volunteers will be recruited from patients with vitiligo and black skin
visiting the UMC Utrecht dermatology & Allergology department and the Dutch
patient*s association for vitiligo will be approached to place an advertisement
on their website.
The first group of volunteers (n=6) will consist of elderly patients with
longstanding vitiligo. During a single visit (~ 15 minutes) two punch biopsies
(4mm diameter) will be taken from sun-exposed lesional and adjacent normal
skin.
The second group of volunteers (n=6) will visit our clinic on two consecutive
days (~ 50 and 15 minutes respectively). The minimal erythemal dose (MED) of
lesional skin will be determined (day 1) and an area of lesional and normal
skin will be exposed to 18 000 mJ per cm2 of SSR (day 1) from which two punch
biopsies (4mm diameter) will be taken twenty four hours later. Two additional
control biopsies will be taken from unexposed lesional and normal skin.
All procedures will be carried out by the principal investigator in the light
department of our outpatient*s clinic.

see study design.

The lesions resulting from the biopsies taken may remain visible for a
prolonged period of time as hypopigmented areas. Induced redness of a small
area of the skin following determination of the MED and exposure to SSR should
cause no physical discomfort and may heal with some scaling within days.
Serious adverse events are highly unlikely. Any effect on the disease itself is
not expected. Patients will receive some financial compensation for their
participation.