Absence of Tyrosinase-Related Protein-2/Dopachrome Tautomerase Transcripts in PBMCs from Vitiligo Patients

Immunohistochemical detection of P53 and Mdm2 in vitiligo

Background:

Vitiligo is a common depigmented skin disorder that is caused by selective destruction of melanocytes. It is generally accepted that the main function of melanin resides in the protection of skin cells against the deleterious effect of ultraviolet rays (UVRs). Association of vitiligo and skin cancer has been a subject of controversy. Occurrence of skin cancer in long-lasting vitiligo is rare despite multiple evidences of DNA damage in vitiliginous skin.

Aim:

To detect the expression of P53 and Mdm2 proteins in both depigmented and normally pigmented skin of vitiligo patients and to compare it to control subjects suffering from nonmelanoma skin cancer (NMSC).

Materials and Methods:

Thirty-four patients with vitiligo and 30 age and sex-matched patients with nodulo-ulcerative basal cell carcinoma (BCC) as a control group were selected. Both patients and control subjects had outdoor occupations. Skin biopsies were taken from each case and control subjects. Histopathological examination of Hematoxylin and eosin-stained sections was done. Expression of P53 and Mdm2 proteins were examined immunohistochemically.

Results:

Both P53 and Mdm2 were strongly expressed in depigmented as well as normally pigmented skin of vitiligo patients. This expression involved the epidermis, skin adnexa and blood vessels with significant differences between cases and controls.

Conclusions:

The overexpression of P53 and Mdm2 proteins in both normally pigmented and depigmented skin of patients with vitiligo could contribute to the decreased occurrence of actinic damage and NMSC in these patients.

Probiotic attributes ofLactobacillusstrains isolated from food and of human origin

Lactobacilli isolated from various sources were identified on the basis of 16S–23S rRNA gene intergenic region amplification and subsequent sequencing of the smaller intergenic region. Anin vitroanalysis of probiotic properties including binding, ability to tolerate different concentrations of bile, survival in acidic buffer and antimicrobial activity of four different isolates and two standard strains (Lactobacillus plantarumAmerican Type Culture Collection (ATCC) 8014 andL. rhamnosusGG (LGG)) was carried out. The ability of each isolate to stimulate Caco-2 cells, human peripheral blood mononuclear cells (PBMC) and THP-1 cells resulting in immunomodulation of these cells was analysed. IsolatesL. rhamnosusCS25 andL. delbrueckiiM and standard strain ATCC 8014 showed broad antimicrobial activity, and isolates CS25 (percentage of survival 6·9 % at pH 2·5, 5·1 % at pH 2·0) andL. plantarumCS23 (5·7 % at pH 2·5, 4·9 % at pH 2·0) have shown good tolerance to acidic pH. Isolate CS23 showed a good survival (14 %) after 2 h incubation in de Man, Rogosa and Sharpe (MRS) medium containing 3 % bile salts. Isolates CS23, CS25 andL. fermentumASt1 could stimulate Caco-2 cells, human PBMC and THP-1 cells for a strong and varied immunomodulatory response in these cells. Though LGG showed poor antimicrobial activity as well as bile and acid tolerance, it was found to be the best binding strain tested. Child faecal isolate CS23 from the present study showed high binding ability (seventeen bacteria/Caco-2), high tolerance to acidic pH and bile salts and significant immunomodulation; therefore it is a good potential probiotic candidate.

MART-1 transcript is absent in PBMCs from Vitiligo patients

Mechanisms occurring in the thymus and periphery are responsible for the generation and maintenance of tolerance in the immune system. Various reports have shown that the existence of an antigen in the peripheral circulation results in tolerance induction towards that protein. These observations imply that the lack of a self antigen can lead to induction of autoimmunity. Previously we have reported that Tyrosinase related protein-2 (TRP-2) transcripts from peripheral blood mononuclear cells (PBMCs) are absent in vitiligo patients but present in healthy individuals. Here, we show that MART1 (Melanoma antigen recognized by T cells) transcripts are not detected in the PBMCs of vitiligo patients but is detected in healthy controls. Our result suggests that as MART1 is not expressed in the PBMCs, MART1 is also not available for induction and maintenance of peripheral tolerance in vitiligo patients. We therefore conclude that nonexpression of MART1 in PBMCs of vitiligo patients may be somehow responsible for the tolerance breakdown finally resulting in the induction of autoimmunity seen against these self antigens in vitiligo.