Vitiligo affects 1% of the worldwide population. Halting disease progression and repigmenting the lesional skin represent the two faces of therapeutic challenge in vitiligo. We performed transcriptome analysis on lesional, perilesional, and non-depigmented skin from vitiligo patients and on matched skin from healthy subjects. We found a significant increase in CXCL10 in non-depigmented and perilesional vitiligo skin compared with levels in healthy control skin; however, neither CXCL10 nor other immune factors were deregulated in depigmented vitiligo skin. Interestingly, the WNT pathway, which is involved in melanocyte differentiation, was altered specifically in vitiligo skin. We demonstrated that oxidative stress decreases WNT expression/activation in keratinocytes and melanocytes. We developed an ex vivo skin model and confirmed the decrease activation of the WNT pathway in human skin subjected to oxidative stress. Finally, using pharmacological agents that activate the WNT pathway, we treated ex vivo depigmented skin from vitiligo patients and successfully induced differentiation of resident stem cells into pre-melanocytes. Our results shed light on the previously unrecognized role of decreased WNT activation in the prevention of melanocyte differentiation in depigmented vitiligo skin. Furthermore, these results support further clinical exploration of WNT agonists to repigment vitiligo lesions.

Stable expression of human groups IIA and X secreted phospholipases A 2 (hGIIA and hGX) in CHO-K1 and HEK293 cells leads to serum-and interleukin-1␤-promoted arachidonate release. Using mutant CHO-K1 cell lines, it is shown that this arachidonate release does not require heparan sulfate proteoglycan-or glycosylphosphatidylinositol-anchored proteins. It is shown that the potent secreted phospholipase A 2 inhibitor Me-Indoxam is cell-impermeable. By use of Me-Indoxam and the cellimpermeable, secreted phospholipase A 2 trapping agent heparin, it is shown that hGIIA liberates free arachidonate prior to secretion from the cell. With hGX-transfected CHO-K1 cells, arachidonate release occurs before and after enzyme secretion, whereas all of the arachidonate release from HEK293 cells occurs prior to enzyme secretion. Immunocytochemical studies by confocal laser and electron microscopies show localization of hGIIA to the cell surface and Golgi compartment. Additional results show that the interleukin-1␤-dependent release of arachidonate is promoted by secreted phospholipase A 2 expression and is completely dependent on cytosolic (group IVA) phospholipase A 2 . These results along with additional data resolve the paradox that efficient arachidonic acid release occurs with hGIIAtransfected cells, and yet exogenously added hGIIA is poorly able to liberate arachidonic acid from mammalian cells.Phospholipases A 2 (PLA 2 s) 1 are a class of enzymes that release fatty acids from the sn-2 position of glycero-phospholipids. Biomedical interest in these enzymes stems from the finding that the liberation of arachidonic acid for the biosynthesis of the eicosanoids (prostaglandins, leukotrienes, and others) is mediated in mammalian cells by one or more PLA 2 s. Current evidence favors a role for cytosolic phospholipase A 2 -␣ (cPLA 2 -␣, also known as group IVA PLA 2 ) as a major component of the arachidonate releasing signal transduction pathway (1-3). Mammals also contain a large number of secreted phospholipases A 2 (sPLA 2 s) (4, 5), and the possible participation of these enzymes in arachidonate release is under active investigation. For example, group V sPLA 2 is present in the macrophage-like cell line p388D1 and contributes a portion of the arachidonate released in response to lipopolysaccharide (6). Exogenous addition of groups V and X sPLA 2 s to a variety of mammalian cells leads to arachidonate release (7-10). There is some evidence to suggest that the action of cPLA 2 -␣ is a prerequisite for sPLA 2 function in cells (11,12) and even for the vice versa scenario (13-15), but such cross-talk between PLA 2 s remains poorly understood.To assess the arachidonate releasing capacity of PLA 2 s in mammalian cells, CHO and HEK293 cell lines that stably express the various enzymes have been established (16 -20). The behavior of human group IIA (hGIIA) and human group X (hGX) sPLA 2 s when transfected in HEK293 and CHO cells has been extensively studied. hGIIA is secreted from HEK293 cells, and most of the extracellular enzyme is a...

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.

Acne is the most common inflammatory dermatosis, affecting up to 85% of the 11-30 years old world population. [1] This disease is subdivided according to severity graduation, from minor to severe acne, and affects different body localizations from face to back. [2] The mechanisms leading to severe acne, representing up to 20% of acne patients, are still poorly understood, although Cutibacterium acnes (C. acnes) appears as a key player of acne physiopathology.Recently, an increasing interest was observed related to skin microbiota's impact on innate immunity, and subsequently, on inflammatory dermatoses physiopathology. [3,4] Two major studies previously decrypted skin microbiota in acne context; however, this topic remains poorly documented-especially on the back-and the sampling methodologies used were quite controversial. [5][6][7] Indeed, Barnard et al and Fitz-Gibbon et al both described skin microbiome in acne and healthy context, using strip from nose of patients. [8,9] These studies both showed that no clear difference was observed in C. acnes abundance between healthy and acne individuals, whereas recent evidences highlighted a loss of C. acnes subgroups diversity in severe acne context. [10] On the other hand, studying skin bacterial populations using either 16S metataxonomic method or shotgun, to reveal the skin microbial composition, have never been described before in severe back acne context. The present study aims to investigate skin microbiota in patients with severe acne of the back vs healthy controls, sampling two major localizations of acne lesions: the back and the face. | MATERIAL AND ME THODS | Recruitment of healthy volunteers and patientsIn the present clinical study, 24 patients with severe acne of the back and 12 healthy volunteers were enrolled. Regarding the skin type, all Abstract Acne is the most common inflammatory skin disease, affecting up to 85% of the 11-30 years old world population. Skin microbiota appears as a key player involved in several skin dermatoses physiopathology. Here, we show that inflammatory skin is associated with changes in the skin microbiota composition on the back of severe acne patients but also on the face of patients where acne was scored as mild to moderate, comparing with healthy controls. Changes were observed particularly on skin commensals Propionibacteriaceae, Staphylococcaceae and Enterococcaceae families, suggesting the importance of the balance between skin commensals to maintain skin homeostasis and control skin inflammatory process. K E Y W O R D Sacne, inflammatory skin diseases, innate immunity, microbiology, microbiome

Human group II secretory phospholipase A 2 (sPLA 2 ) is an enzyme found in the ␣ granules of platelets and at inf lammatory sites. Although its physiological function is unclear, sPLA 2 can inhibit blood coagulation reactions independent of its lipolytic action. To study the molecular basis of PLA 2 activities, we developed a total chemical synthesis of sPLA 2 by chemical ligation of large unprotected peptides. The synthetic segments PLA 2 -(1-58)-␣ COSCH 2 COOH and PLA 2 -(59-124) were prepared by stepwise solid-phase peptide synthesis and ligated to yield a peptide bond between Gly 58 and Cys 59 . The 124-residue polypeptide product (mass: 13,920 ؎ 2 Da) was folded to yield one major product (mass: 13,905 ؎ 1 Da), the loss of 15 ؎ 3 Da ref lecting the formation of seven disulfide bonds. Circular dichroism studies of synthetic sPLA 2 showed ␣-helix, ␤-structure, and random coil contents consistent with those found in the crystal structure of sPLA 2 . Synthetic sPLA 2 had k cat and K m values identical to those of recombinant sPLA 2 for hydrolysis of 1,2-bis(heptanoylthio)-phosphatidylcholine. Synthetic sPLA 2 , like recombinant sPLA 2 , inhibited thrombin generation from prothrombinase complex (factors Xa, V, II, Ca 2؉ , and phospholipids). In the absence of phospholipids, both synthetic and recombinant sPLA 2 inhibited by 70% prothrombin activation by factors Xa, Va, and Ca 2؉ . Thus, synthetic sPLA 2 is a phospholipidindependent anticoagulant like recombinant or natural sPLA 2 . This study demonstrates that chemical synthesis of sPLA 2 yields a fully active native-like enzyme and offers a straightforward tool to provide sPLA 2 analogs for structureactivity studies of anticoagulant, lipolytic, or inf lammatory activities.