Nonclinical and human pharmacology of the potent and selective topical retinoic acid receptor-γ agonist trifarotene.

BACKGROUND: First- and third-generation retinoids are the main treatment for acne. Even though efficacious, they lack full selectivity for retinoic acid receptor (RAR) γ, expressed in the epidermis and infundibulum. OBJECTIVES: To characterize the in vitro metabolism and the pharmacology of the novel retinoid trifarotene. MATERIALS AND METHODS: In vitro assays determined efficacy, potency and selectivity on RARs, as well as the activity on the expression of retinoid target genes in human keratinocytes and ex vivo cultured skin. In vivo studies investigated topical comedolytic, anti-inflammatory and depigmenting properties. The trifarotene-induced gene expression profile was investigated in nonlesional skin of patients with acne and compared with ex vivo and in vivo models. Finally, the metabolic stability in human keratinocytes and hepatic microsomes was established. RESULTS: Trifarotene is a selective RARγ agonist with > 20-fold selectivity over RARα and RARß. Trifarotene is active and stable in keratinocytes but rapidly metabolized by human hepatic microsomes, predicting improved safety. In vivo, trifarotene 0·01% applied topically is highly comedolytic and has anti-inflammatory and antipigmenting properties. Gene expression studies indicated potent activation of known retinoid-modulated processes (epidermal differentiation, proliferation, stress response, retinoic acid metabolism) and novel pathways (proteolysis, transport/skin hydration, cell adhesion) in ex vivo and in vivo models, as well as in human skin after 4 weeks of topical application of trifarotene 0·005% cream. CONCLUSIONS: Based on its RARγ selectivity, rapid degradation in human hepatic microsomes and pharmacological properties including potent modulation of epidermal processes, topical treatment with trifarotene could result in good efficacy and may present a favourable safety profile in acne and ichthyotic disorders.

Atrophic scar formation in patients with acne involves long-acting immune responses with plasma cells and alteration of sebaceous glands.

BACKGROUND: Possible outcomes of acne lesions are atrophic scars, which may cause serious psychological distress. Current treatments for postacne scarring often require invasive procedures. Pathophysiological studies on acne scarring have only investigated the first week of papule life. OBJECTIVES: To study the pathophysiology of atrophic scar formation to identify molecular and cellular pathways that can lead to new therapies for the prevention of acne scarring. METHODS: Large-scale gene expression profiling and immunohistochemistry analysis were performed on uninvolved skin and papules in both scar-prone (SP) and non-scar-prone (NSP) patients with acne, at different time points. RESULTS: Gene expression and immunohistochemistry analyses showed a very similar immune response in 48-h-old papules in SP and NSP populations, characterized by elevated numbers of T cells, neutrophils and macrophages. However, the immune response only persisted in SP patients in 3-week-old papules, and was characterized by an important B-cell infiltrate. Transient downmodulation of sebaceous gland markers related to lipid metabolism was observed in 48-h-old papules in NSP patients, followed by normalization after 3 weeks. In contrast, in SP patients a drastic reduction of these markers persisted in 3-week-old papules, suggesting an irreversible destruction of sebaceous gland structures after inflammatory remodelling in SP patients with acne. CONCLUSIONS: Long-lived acne papules are characterized by a B-cell infiltrate. A relationship exists between the duration and severity of inflammation and the alteration of sebaceous gland structures, leading to atrophic scar formation in acne.

An innovative method to quantitate tissue integration of hyaluronic acid-based dermal fillers.

BACKGROUND/PURPOSE: Following intradermal injection, hyaluronic acid (HA)-based fillers tend to spread within the reticular dermis and to distribute between the dermal fibers. This biointegration is commonly measured qualitatively using histological methods. We developed a "toolbox" consisting of a visual scoring and a semi-automatic image analysis method using internal developed algorithm to quantitate the biointegration of Restylane® in histological sections. METHODS: Restylane® was injected intradermally in the abdominal skin of 10 healthy human subjects scheduled for abdominoplasty. The injections were performed either in vivo before surgery or ex vivo on samples taken post-surgery at different time points. The samples were processed for histology by visual scoring and image analysis using algorithms developed in Definiens to assess biointegration. RESULTS: The image analysis segmentation was accurate with <5% manual changes. Furthermore, the results calculated with the semi-automatic method were consistent with the visual scores obtained on injected human skin samples by means of a 5-grade photographic scale. A modified hematoxylin-eosin staining was found adequate to visualize both, the filler and the general morphology, on the same section. An excellent correlation was observed between the integration results obtained with PAS/Alcian Blue and HE-stained slides, allowing for a single staining in future studies. CONCLUSION: We developed a modified HE staining histological method and a new histomorphometric image analysis tool to quantitate biointegration of HA-based fillers in human skin. The results obtained in this study confirmed the known intermediate biointegration properties of Restylane®, thus validating these innovative methods.

[Pap test: liquid-based--thin-layer. A new method: results]. / Frottis de dépistage : recueil en suspension--étalement en couche mince. Méthode novatrice : analyse des résultats.

OBJECTIVES: Evaluation of the thin-layer technique we have developed. PATIENTS AND METHOD: An adequate shaking, a calibration and a centrifugation in liquid phase are the essential and specific stages of this technique. More than 160 000 samples were prepared according to this methodology in eight years. RESULTS: The immediate profit of the technique is the increase of the number of interpretable samples: 99.9%. First years: net increase of the lesion detection rate in comparison with conventional cervical smear. 1.7 versus 0.9% for the low-grade lesions; 1.0 versus 0.4% for the high-grade lesions. After three years the detection rate of low-grade lesions remained high: 1.7% while the ASCUS/AGUS and high-grade lesions decreased to reach, respectively, 1.1 and 0.4%. DISCUSSION AND CONCLUSION: The quality of the thin-layer preparation, the best approach of the endocervical pathology, and the possibility to identify rare events, allowed us at first to increase detection of lesions. After three years of "picking up" of lesions forgotten by conventional cervical smear, the rate of high-grade lesions stabilised in 0.4%. Thus, it is advisable to take into account the notion of time as for the estimate of the lesion rate when using thin-layer technique compared with that of conventional cervical smear.

A comparative study of DNA content as measured by flow cytometry and image analysis in 1864 specimens.

Both flow cytometry (FCM) and image cytometry (ICM) were used to assess the DNA content of 1864 lesions (benign and malignant tumors, dysplasias, dystrophies and normal tissue). In total there were 1274 cases of bladder washings and 590 fresh solid tumor specimens. Of the total number of specimens, 1737 (93.2%) were satisfactorily assessed by ICM and 1424 (76.4%) by FCM. In only 100 (5.4%) cases was the DNA content unable to be assessed by either method. When bladder washings were excluded, 99.5% of samples could be evaluated by one method or the other. Concomitant determinations with both technologies were made in 1397 cases. When comparing all evaluable cases, concordance between the ploidy measurements of FCM and ICM was 92.8% (1297 concordant cases out of 1397). When bladder washings were excluded and only solid tumors considered, the concordance was 96.1% (545 concordant cases out of 567). From the experience of applying ICM and FCM to the 1864 lesions the technical limitations of each method became evident, specifically the problems of doubtful DNA diploidy and doubtful DNA aneuploidy. When there were 'doubtful' ploidy findings, the cause was generally found to be morphologic alterations of the nuclei or differences in staining procedures employed, and often the complementary use of both FCM and ICM provided ploidy clarification in questionable cases.

Transmeiotic differentiation of male germ cells in culture.

A cell culture system that supports the differentiation of male germ cells through meiosis is described. It takes advantage of the properties of a cell line, 15P-1, established from testicular cells of transgenic mice that express the large T protein of polyoma virus in the seminiferous epithelium. This line exhibits features characteristics of Sertoli cells, including transcription of the Wilms' tumor (WT1) and Steel genes. Cells of the 15P-1 type support the meiotic and postmeiotic differentiation in cocultures of diploid premeiotic germ cells into haploid spermatids expressing the protamine (Prm-1) gene. When cocultured with 15P-1 cells, testicular cells explanted from immature 9-day-old animals, before the onset of the first meiosis, generated tetrads of haploid cells with the morphology of round spermatids and initiated protamine transcription.