Immunoproteomic identification and characterization of Ni2+-regulated proteins implicates Ni2+ in the induction of monocyte cell death

Nickel allergy is the most common cause of allergic reactions worldwide, with cutaneous and systemic effects potentially affecting multiple organs. Monocytes are precursors of not only macrophages but also dendritic cells, the most potent activators of nickel hypersensitivity. Monocytes are themselves important antigen-presenting cells, capable of nickel-specific T-cell activation in vivo and in vitro, in addition to being important for immediate innate immune inflammation. To elucidate early Ni2+-dependent inflammatory molecular mechanisms in human monocytes, a Ni2+-specific proteomic approach was applied. Quantitative two-dimensional (2D) differential gel electrophoresis and Delta2D software analyses coupled with matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) revealed that Ni2+ significantly regulated 56 protein species, of which 36 were analyzed by MALDI-MS. Bioinformatics analyses of all identified proteins resulted in Ni2+-associated functional annotation clusters, such as cell death, metal ion binding, and cytoskeletal remodeling. The involvement of Ni2+ in the induction of monocyte cell death, but not T-cell death, was observed at Ni2+ concentrations at or above 250 µM. Examination of caspase activity during Ni2+-mediated cell death revealed monocytic cell death independent of caspase-3 and -7 activity. However, confocal microscopy analysis demonstrated Ni2+-triggered cytoskeletal remodeling and nuclear condensation, characteristic of cellular apoptosis. Thus, Ni2+-specific peripheral blood mononuclear cell stimulation suggests monocytic cell death at Ni2+ concentrations at or above 250 µM, and monocytic effects on immune regulation at lower Ni2+ concentrations

Comparative proteomics of exosomes secreted by tumoral jurkat t cells and normal human t cell blasts unravels a potential tumorigenic role for valosin-containing protein

We have previously characterized that FasL and Apo2L/TRAIL are stored in their bioactive form inside human T cell blasts in intraluminal vesicles present in multivesicular bodies. These vesicles are rapidly released to the supernatant in the form of exosomes upon re-activation of T cells. In this study we have compared for the first time proteomics of exosomes produced by normal human T cell blasts with those produced by tumoral Jurkat cells, with the objective of identify proteins associated with tumoral exosomes that could have a previously unrecognized role in malignancy. We have identified 359 and 418 proteins in exosomes from T cell blasts and Jurkat cells, respectively. Interestingly, only 145 (around a 40%) are common. The major proteins in both cases are actin and tubulin isoforms and the common interaction nodes correspond to these cytoskeleton and related proteins, as well as to ribosomal and mRNA granule proteins. We detected 14 membrane proteins that were especially enriched in exosomes from Jurkat cells as compared with T cell blasts. The most abundant of these proteins was valosin-containing protein (VCP), a membrane ATPase involved in ER homeostasis and ubiquitination. In this work, we also show that leukemic cells are more sensitive to cell death induced by the VCP inhibitor DBeQ than normal T cells. Furthermore, VCP inhibition prevents functional exosome secretion only in Jurkat cells, but not in T cell blasts. These results suggest VCP targeting as a new selective pathway to exploit in cancer treatment to prevent tumoral exosome secretion

Safe cosmetics without animal testing? Contributions of the EU Project Sens-it-iv

The 7th Ammendment to the Cosmetics Directive of the European Commission (Directive 76/768/EEC2) bans the marketing of cosmetics containing animal-tested ingredients since March 2009. Excepted are only tests for repeated dose toxicity, for which the animal ban will come into effect by 2013. One major concern for cosmetics, i.e. the risk of containing skin (contact) sensitizers, has in the past been addressed almost exclusively by animal testing. It is this problem attracting the central interest of the integrated research project Sens-it-iv (Novel Testing Strategies for in vitro Assessment of Allergens, http://www.sens-it-iv.eu), funded by the EC within framework 6 since October 2005. Here, the 28 Sens-it-iv partners from 10 European States present the 5 most promising types of in vitro assays selected for further refinement. These are: (1) a human epidermal equivalent (EE) model to rank contact allergens according to their sensitizing potency, (2) identification of contact sensitizers, including pro-haptens, through intracellular production of IL-18 by the human keratinocyte cell line NCTC 2544, (3) determination of activation markers such as CD86, CD54 and most prominently CXCL8 (IL-8) on/in dendritic cell lines, (4) contact sensitizer-specific migration of MUTZ Langerhans cells towards the chemokine CXCL12, and (5) the allergen-specific activation and proliferation of na\uefve human T cells. Ongoing genomic and proteomic experiments are in the process of identifying larger sensitizer-specific biological marker signatures to be integrated into the above assays. We hope to supply the European control agencies with a basis for further validation of in vitro assays by the end of 2010

Current knowledge on biomarkers for contact sensitization and allergic contact dermatitis.

Contact sensitization is common and affects up to 20% of the general population. The clinical manifestation of contact sensitization is allergic contact dermatitis. This is a clinical expression that is sometimes difficult to distinguish from other types of dermatitis, for example irritant and atopic dermatitis. Several studies have examined the pathogenesis and severity of allergic contact dermatitis by measuring the absence or presence of various biomarkers. In this review, we provide a non-systematic overview of biomarkers that have been studied in allergic contact dermatitis. These include genetic variations and mutations, inflammatory mediators, alarmins, proteases, immunoproteomics, lipids, natural moisturizing factors, tight junctions, and antimicrobial peptides. We conclude that, despite the enormous amount of data, convincing specific biomarkers for allergic contact dermatitis are yet to be described

Proteomic allergen-peptide/protein interaction assay for the identification of human skin sensitizers

Item does not contain fulltextModification of proteins by skin sensitizers is a pivotal step in T cell mediated allergic contact dermatitis (ACD). In this process small reactive chemicals interact covalently or non-covalently with cellular or extracellular skin self-proteins or self-peptides to become recognized by the human immune system. Aiming to develop a novel non-animal in vitro test system for predicting sensitization potential of small reactive chemicals in human skin the allergen-peptide/protein interaction assay (APIA) has been developed. By applying modern proteomic technologies together with a target peptide containing all amino acids, the assay permits the profiling of all amino acid specific allergen-peptide interactions. Moreover, potentially crucial allergen-specific Cys-modifications are qualitatively monitored by mass spectrometry and confirmed by a dual peptide approach. Assay conditions chosen mimic the distinct human epidermal reactivity compartments of the skin surface (pH 5.5), stratum basale (pH 6.8), and typical physiological conditions (pH 7.4). An extreme as well as a moderate human contact sensitizer produced Cys-specific mass shifts, whereas a skin irritant did not. Our data indicate that MALDI-MS based and skin-related in vitro technology platforms - like the APIA - are promising tools in developing alternative non-animal allergen assays. This will assist in chemical classification and next generation risk assessment strategies, including REACH and experimental immunotoxicology