Acne is a common disorder, especially during adolescence. One of the most effective treatments for severe acne is isotretinoin (13-cis Retinoic Acid (RA)), which is a known teratogen. Isotretinoin is only the second drug (after thalidomide) to be placed on a FDA national registry due to public health concerns regarding teratogenicity. This registry includes patients, pharmacists, prescribers and wholesalers. It is important to determine the mechanism of action of 13-cis RA, in order to develop an effective alternative drug without serious side effects. The laboratory has been involved in identifying key players in the response to isotretinoin through gene array expression analysis of the skin of patients treated with 13-cis RA and through work with a sebocyte cell-line. The gene with the greatest increase in expression at 1 week of treatment with 13-cis RA is lipocalin 2 (Icn2), which encodes the neutrophil-gelatinase associated lipocalin (NGAL) protein. The overall goal of this investigation is to determine if the effects of 13-cis RA in inducing apoptosis in sebaceous glands is mediated by NGAL.
The first aim of the proposed work is to determine if there is an increase in NGAL secretion on the skin of patients treated with isotretinoin. The amount of NGAL present on the skin will be assessed by performing skin washings of specific areas followed by an ELISA. Skin NGAL levels will be correlated with plasma NGAL levels of patients during the course of treatment with isotretinoin. The results of these studies should reveal whether or not NGAL is available on the skin in response to 13-cis RA treatment and the duration of the response. Preliminary data in the laboratory suggests that sebocytes express the recently identified NGAL receptor and undergo apoptosis in response to NGAL.
The second aim of this proposal is to determine if NGAL induces apoptosis by changing intracellular iron levels in TSS-1 sebocytes. This will be tested first by using recombinant human NGAL loaded with iron (holo-NGAL) and without iron (apo-NGAL). TSS-1 cells will be treated with 13-cis retinoic acid, apo-NGAL, and holo-NGAL and iron status of the cells will be assessed using western blotting for ferritin and colormetric assay of cell supernatants. These experiments will help to elucidate the effect NGAL has on iron flux in sebocyte cell line. The long-term goal is to determine whether NGAL is a promising alternative to 13-cis RA as a treatment for acne. This research will help to characterize neutrophil-gelatinase associated lipocalin's (NGAL) effect on the skin and will hopefully lead to the discovery of therapies alternative to 13-cis RA, which is known to cause birth defects.
| Lumsden, K R; Nelson, A M; Dispenza, M C et al. (2011) Isotretinoin increases skin-surface levels of neutrophil gelatinase-associated lipocalin in patients treated for severe acne. Br J Dermatol 165:302-10 |
