الفهرس 
NTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
Vitiligo is an idiopathic acquired sometimes familial leukoderma characterized histologically by absence of melanocytes and often by other abnormalities. It may affect 0.5-1% of the world population.
The cause of vitiligo is still unknown but there are many theories concerning the cause such as the autoimmune, autocytotoxic and neural hypothesis.
The liver X receptors (LXRs), LXR-α and LXR-β are members of the nuclear hormone receptor superfamily of ligand-activated transcription factors.
LXRs has been shown to be expressed in skin. LXR-α and LXR-β are expressed in sebaceous glands, sweat glands, hair follicle, keratinocytes and throughout all layers of the human epidermis.
activation of LXR-α decreases keratinocytes proliferation. Epidermal melanocytes form a functional and structural unit with neighboring keratinocytes that produce several mediators that support the growth of melanocytes and the process of melanization.
The aim of the present study is to investigate the expression of lXR-α in vitiligo lesions and to study its possible role in disease pathogenesis.
This case-control study was carried out on 44 subjects. These included 24 patients with vitiligo and 20 age and sex matched normal subjects as a control group. Every case was subjected to complete history taking, complete general examination and dermatologic examination.
Three millimeter punch biopsies were taken under 2% lignocaine local anesthesia from vitiliginous skin of patients and from perilesional skin which is 1-5 mm away from marginal area . Additional biopsy was taken from distant non lesional skin . Biopsies were taken from control group from site-matched areas as lesional biopsies of cases. Biopsies were fixed in neutral formalin 10%,
and submitted to routine tissue processing ending with paraffin embedded blocks formation, in Pathology Department, Faculty of Medicine, Menoufiya University. Several paraffin sections, each 4 um thick, were cut from each block, one of them was stained by haematoxylin and eosin to evaluate pathological changes and the other sections were cut on poly L lysine coated slides for immunostaining procedsure.
Haematoxylin and eosin stained sections of vitiliginous skin revealed presence of epidermal atrophy, basal and suprabasal vacuolization as a sign of degeneration, basement membrane (BM) thickening, dermal perivascular inflammatory infiltrate, and dermal angiogenesis.
LXR-α immunostaining showed statistical significant difference between lesional area and non lesional (normal) area of vitiligo regarding epidermal intensity (P=0.008), epidermal H score (P<0.001), and hair follicle H score (p˂0.001) in fovour of lesional area of vitiligo . There was a statistically significant difference between lesional and perilesional areas of vitiligo regarding epidermal H score and hair follicle H score (P=0.009 and P<0.001), where the higher H scores were detected in perilesional area of vitiligo.
LXR-α immunostaining showed statistical significant difference between lesional area of vitiligo and healthy skin (control group) regarding epidermal intensity (P=0.02), epidermal H score (P<0.001), and hair follicle H score (p˂0.001) in fovour of lesional area of vitiligo.
from the present study, LXR-α was upregulated in vitiligenous skin
keratinocytes with highest expression in perilesional area, that may share in
vitiligo pathogenesis.