Comparative Studies on Naturally Occurring Antikeratin Antibodies in Human Sera

Comparative studies on the specificity of the so-called antiepidermal antibodies (Abs) found in human sera were performed by immunoblotting, enzyme-linked immunosorbent assay (ELISA), and immunoelectron microscopy (LEM). After a screening test by indirect immunofluorescence (IF), sera obtained from patients with various diseases and controls could be classified in 5 different groups according to the IF patterns on the epidermis: sera reactive with: (1) the stratum corneum (SC); (2) the upper layer (U-Cyt); (3) the whole epidermis (G-Cyt); (4) basal cells (B-Cyt); and (5) negative ones. By immunoblotting, all the 23 IF-positive sera were found to bind to one or more keratin bands, and did not show any reactivity with epidermal Nonidet P-40 soluble proteins. SC-Abs were mainly directed against a 67 kD Keratin band, whereas U-Cyt- and G-Cyt-Abs bound to both 58-56 kD and 67-63 kD keratins. B-Cyt-Abs reacted strongly with 63 kD keratins and slightly with a 50 kD band. Antikeratin Abs were detected by immunoblotting even in the IF-negative sera. The ELISA study showed that sera with high IF titers contained high levels of antikeratin Abs. In the IEM study using sera containing U-Cyt- or B-Cyt-Abs, 2 distinct reaction patterns were demonstrated: U-Cyt-Abs stained tonofilaments of suprabasal keratinocytes, while B-Cyt- Abs characteristically reacted with those of basal cells. Moreover, SC-, U-Cyt-, and G-Cyt-Abs were absorbed out by insoluble epidermal proteins, and B-Cyt-Abs were decreased in titer after the absorption test. The present study provides strong evidence that most, though not all, human antiepidermal Abs are directed against different keratin polypeptides, and that antikeratin Abs commonly occur in almost all human sera

Production et régulation de VEGF, Vascular Endothelial Growth Factor, par les kératinocytes et les fibroblastes humains normaux

Parmi les facteurs impliqués dans le développement de l'érythème cutané, le facteur de perméabilité vasculaire (VPF/VEGF-A) qui constitue un puissant vasodilatateur, exerce un rôle majeur. Il est synthétisé de manière constitutive par les kératinocytes et les fibroblastes dermiques, et surexprimé in vivo en conditions inflammatoires, notamment par les cellules épidermiques. Notre étude a précisé la régulation de VEGF-A par des facteurs d'agression exogènes (UV), endogènes (cytokines pro-inflammatoires, facteurs de croissance) et des extraits végétaux dans des cultures primaires de kératinocytes et de fibroblastes humains normaux. Parallèlement, nous avons étudié l'expression des nouveaux membres de la famille VEGF, VEGF-B, -C et -D, par ces cellules activées sous l'action de facteurs de croissance ou du TNF . L'expression des différents VEGFs suggère un contrôle de l'angiogenèse et de la lymphangiogenèse cutanées par les principales cellules résidentes de la peau.LYON1-BU.Sciences (692662101) / SudocSudocFranceF

REGULATION DES MEDIATEURS IMPLIQUES DANS L'ERYTHEME CUTANE PHOTO-INDUIT (APPROCHE IN VITRO (DOCTORAT : BIOLOGIE EN PHARMACOLOGIE CUTANEE))

LYON1-BU Santé (693882101) / SudocPARIS-BIUM (751062103) / SudocPARIS-BIUP (751062107) / SudocSudocFranceF

Gamma Interferon Potently Induces Tryptophanyl-tRNA Synthetase Expression in Human Keratinocytes

Incubation of human keratinocytes with gamma interferon (γ-IFN) induces the synthesis of a 53-kDa protein of unknown nature and function. We report the identification of this protein through amino acid microsequencing. The NH2-terminal amino acid sequence of the 53-kDa antigen demonstrated that this protein was tryptophanyl-tRNA synthetase (Frolova et al, Gene 109:291–296, 1991, Genbank accession number 61715). This result was validated by the sequencing of tryptic peptides. Identification of the 53-kDa γ-IFN – induced protein was confirmed by immunoblotting with an antiserum directed against beef pancreas tryptophanyl-tRNA synthetase. Northern blot analysis using a synthetic oligonucleotidic 32P-labeled probe evidenced a 3.1-kb transcript in γ-IFN – treated cells indicating that the gene was regulated at the pre-translational level.These data show that γ-IFN potently induces in keratinocytes the expression of an enzyme directly involved in protein biosynthesis. Elevated levels of tryptophanyl-tRNA synthetase in treated cultured keratinocytes might be involved in the cell-growth – inhibitory activity of gamma interferon