The Receptor for Advanced Glycation End Products Is Highly Expressed in the Skin and Upregulated by Advanced Glycation End Products and Tumor Necrosis Factor-Alpha

Advanced glycation end products (AGEs) form non-enzymatically from reactions of proteins with reducing sugars. In the skin, AGEs were reported to accumulate in dermal elastin and collagens and to interact nonspecifically with the cell membrane of dermal fibroblasts. Therefore, AGEs may influence the process of skin aging. We investigated the presence of the AGE receptor RAGE in skin and the influence of AGEs on receptor expression and the formation of extracellular matrix (ECM). Sections of sun-protected and sun-exposed skin were analyzed with monoclonal antibodies against (RAGE), heat-shock protein 47, factor XIIIa, CD31, and CD45. RAGE was mainly expressed in fibroblasts, dendrocytes, and keratinocytes and to a minor extent in endothelial and mononuclear cells. Human foreskin fibroblasts (HFFs) highly expressed RAGE on the protein and mRNA level when analyzed by quantitative Western blotting and real-time PCR. Incubation of HFFs with the specific RAGE ligand Nε-(carboxymethyl)lysine-modified BSA (CML-BSA) and tumor necrosis factor-alpha resulted in significant upregulation of RAGE expression. CML-BSA induced a mildly profibrogenic pattern, increasing connective tissue growth factor, transforming growth factor-beta (TGF-β)1, and procollagen-α1(I) mRNA, whereas expression of matrix metalloproteinase (MMP)-1, −2, −3, and −12 was unaffected. We conclude that in HFFs, AGE–RAGE interactions may influence the process of skin aging through mild stimulation of ECM gene expression

Quantitative Proteomics of Polarised Macrophages Derived from Induced Pluripotent Stem Cells

Macrophages (M(Φ)) are highly heterogenous and versatile innate immune cells involved in homeostatic and immune responses. Activated M(Φ) can exist in two extreme phenotypes: pro-inflammatory (M1) M(Φ) and anti-inflammatory (M2) M(Φ). These phenotypes can be recapitulated in vitro by using ligands of toll-like receptors (TLRs) and cytokines such as IFNγ and IL-4. In recent years, human induced pluripotent stem cells (iPSC)-derived M(Φ) have gained major attention, as they are functionally similar to human monocyte-derived M(Φ) and are receptive to genome editing. In this study, we polarised iPSC-derived M(Φ) to M1 or M2 and analysed their proteome and secretome profiles using quantitative proteomics. These comprehensive proteomic data sets provide new insights into functions of polarised M(Φ)

Receptor for advanced glycation endproducts (RAGE) deficiency protects against MPTP toxicity

Copyright © 2011 Elsevier Inc. All rights reserved.Peer reviewedPublisher PD

Coffee and Maillard products activate NF-jB\ud in macrophages via H2O2 production

In this study, we investigated the immunomodulatory activity of coffee and Maillard reaction products on macrophages in vitro. Stimulation of macrophages with coffee, but not with raw coffee extract in PBS, led to a 13-fold increased nuclear NF-B translocation. A Maillard reaction mixture (25 mM D-ribose/L-lysine, 30 min at 120°C) increased NF-B translocation 18-fold (in PBS) or six-fold (in medium). MRPs also induced a two-fold increased NF-B translocation in untransfected human embryonic kidney (HEK) cells as well as in HEK cells stably transfected with the receptor for advanced glycation endproducts (RAGE), indicating that the effect was not RAGE mediated. On the other hand, catalase totally abolished coffee- and MRP-induced NF-B translocation. Consequently, up to 366 M hydrogen peroxide was measured in the coffee preparation and Maillard mixtures used for cell stimulation. Stimulation of macrophages with MRPs did not lead to significantly increased IL-6 or NO release. Thus, it can be concluded that coffee and MRPs induce NF-B translocation in macrophages via the generation of hydrogen peroxide