BackgroundPsoriasis is a chronic disease characterized by the development of scaly red skin lesions and possible co-morbid conditions. The psoriasis lesional skin transcriptome has been extensively investigated, but mRNA levels do not necessarily reflect protein abundance. The purpose of this study was therefore to compare differential expression patterns of mRNA and protein in psoriasis lesions.MethodsLesional (PP) and uninvolved (PN) skin samples from 14 patients were analyzed using high-throughput complementary DNA sequencing (RNA-seq) and liquid chromatography-tandem mass spectrometry (LC-MS/MS).ResultsWe identified 4122 differentially expressed genes (DEGs) along with 748 differentially expressed proteins (DEPs). Global shifts in mRNA were modestly correlated with changes in protein abundance (r = 0.40). We identified similar numbers of increased and decreased DEGs, but 4-fold more increased than decreased DEPs. Ribosomal subunit and translation proteins were elevated within lesions, without a corresponding shift in mRNA expression (RPL3, RPS8, RPL11). We identified 209 differentially expressed genes/proteins (DEGPs) with corresponding trends at the transcriptome and proteome levels. Most DEGPs were similarly altered in at least one other skin disease. Psoriasis-specific and non-specific DEGPs had distinct cytokine-response patterns, with only the former showing disproportionate induction by IL-17A in cultured keratinocytes.ConclusionsOur findings reveal global imbalance between the number of increased and decreased proteins in psoriasis lesions, consistent with heightened translation. This effect could not have been discerned from mRNA profiling data alone. High-confidence DEGPs were identified through transcriptome-proteome integration. By distinguishing between psoriasis-specific and non-specific DEGPs, our analysis uncovered new functional insights that would otherwise have been overlooked.Electronic supplementary materialThe online version of this article (doi:10.1186/s13073-015-0208-5) contains supplementary material, which is available to authorized users.

We have synthesized and characterized a new class of heme−peptide complexes using disulfide-linked hairpin-turn and cyclic peptides and compared these to their linear analogues. The binding affinities, helicities, and mechanism of binding of linear, hairpin, and cyclic peptides to [FeIII(coproporphyrin-I)]+ have been determined. In a minimalist approach, we utilize amphiphilic peptide sequences (15-mers), where a central histidine provides heme ligation, and the hydrophobic effect is used to optimize heme−peptide complex stability. We have incorporated disulfide bridges between amphiphilic peptides to make hairpin and even cyclic peptides that bind heme extremely well, roughly 5 × 106 times more strongly than histidine itself. CD studies show that the cyclic peptide heme complexes are completely α-helical. NMR spectra of paramagnetic complexes of the peptides show that the 15-mer peptides bind sequentially, with an observable monopeptide, high-spin intermediate. In contrast, the cyclic peptide complexes ligate both imidazoles cooperatively to the heme, producing only a low-spin complex. Electrochemical measurements of the E 1/2 of the FeIII(coproporphyrin-I)+ complexes of these peptides are all at fairly low potentials, ranging from −215 to −252 mV versus NHE at pH 7.

Exposure of human skin to solar ultraviolet (UV) irradiation induces matrix metalloproteinase-1 (MMP-1) activity, which degrades type I collagen fibrils. Type I collagen is the most abundant protein in skin and constitutes the majority of skin connective tissue (dermis). Degradation of collagen fibrils impairs the structure and function of skin that characterize skin aging. Decorin is the predominant proteoglycan in human dermis. In model systems, decorin binds to and protects type I collagen fibrils from proteolytic degradation by enzymes such as MMP-1. Little is known regarding alterations of decorin in response to UV irradiation. We found that solar-simulated UV irradiation of human skin in vivo stimulated substantial decorin degradation, with kinetics similar to infiltration of polymorphonuclear (PMN) cells. Proteases that were released from isolated PMN cells degraded decorin in vitro. A highly selective inhibitor of neutrophil elastase blocked decorin breakdown by proteases released from PMN cells. Furthermore, purified neutrophil elastase cleaved decorin in vitro and generated fragments with similar molecular weights as those resulting from protease activity released from PMN cells, and as observed in UV-irradiated human skin. Cleavage of decorin by neutrophil elastase significantly augmented fragmentation of type I collagen fibrils by MMP-1. Taken together, these data indicate that PMN cell proteases, especially neutrophil elastase, degrade decorin, and this degradation renders collagen fibrils more susceptible to MMP-1 cleavage. These data identify decorin degradation and neutrophil elastase as potential therapeutic targets for mitigating sun exposure-induced collagen fibril degradation in human skin.

Mendez MP, Morris SB, Wilcoxen S, Du M, Monroy YK, Remmer H, Murphy H, Christensen PJ, Paine III R. Disparate mechanisms of sICAM-1 production in the peripheral lung: contrast between alveolar epithelial cells and pulmonary microvascular endothelial cells. Am J Physiol Lung Cell Mol Physiol 294: L807-L814, 2008. First published February 15, 2008 doi:10.1152/ajplung.00398.2007.-Membrane-associated intercellular adhesion molecule-1 (mICAM-1; CD54) is constitutively expressed on the surface of type I alveolar epithelial cells (AEC). Soluble ICAM-1 (sICAM-1) may be produced by proteolytic cleavage of mICAM-1 or by alternative splicing of ICAM-1 mRNA. In contrast to inducible expression seen in most cell types, sICAM-1 is constitutively released by type I AEC and is present in normal alveolar lining fluid. Therefore, we compared the mechanism of sICAM-1 production in primary cultures of two closely juxtaposed cells in the alveolar wall, AEC and pulmonary microvascular endothelial cells (PVEC). AEC, but not PVEC, demonstrated high-level baseline expression of sICAM-1. Stimulation of AEC with TNF␣ or LPS resulted in minimal increase in AEC sICAM-1, whereas PVEC sICAM-1 was briskly induced in response to these signals. AEC sICAM-1 shedding was significantly reduced by treatment with a serine protease inhibitor, but not by cysteine, metalloprotease, or aspartic protease inhibitors. In contrast, none of these inhibitors effected sICAM-1 expression in PVEC. RT-PCR, followed by gel analysis of total RNA, suggests that alternatively spliced fragments are present in both cell types. However, a 16-mer oligopeptide corresponding to the juxtamembrane region of mICAM-1 completely abrogated sICAM-1 shedding in AEC but reduced stimulated PVEC sICAM-1 release by only 20%. Based on these data, we conclude that the predominant mechanism of sICAM-1 production likely differs in the two cell types from opposite sides of the alveolar wall.regulation; mouse; cell culture; CD54 INTERCELLULAR ADHESION MOLECULE-1 (ICAM-1) is an ϳ100-kDa molecule belonging to the immunoglobulin supergene family. The membrane-bound form of this protein (mICAM-1) serves as a counter receptor for the ␤ 2 -integrins, CD11a/CD18 (LFA-1) and CD11b/CD18 (Mac-1), found on leukocytes. Interactions with mICAM-1 facilitate leukocyte transmigration across the endothelium (34) and over the surface of alveolar epithelial cells (AEC) in the lung (27). A soluble form of the molecule, soluble intercellular adhesion molecule-1 (sICAM-1), is found in serum and in the alveolar lining fluid (7,19,23). sICAM-1 may be generated by proteolytic cleavage and/or alternative splicing of mICAM-1 messenger RNA (4, 35, 37). Like mICAM-1, sICAM-1 interacts with LFA-1/Mac-1 to compete with leukocyte binding to mICAM-1 (36) and to stimulate leukocytes (31).sICAM-1 is normally present in the alveolar lining fluid of humans and mice (7,13,14,16,17,23). We have previously demonstrated that type I AEC are the likely source of sICAM-1 in the alveolar lining fluid and that sICAM-1 is constitutively...