Previous studies have implicated acetylases and deacetylases in regulating the transcriptional activity of NF-B. Here, we show that inhibitors of deacetylases such as trichostatin A (TSA) and sodium butyrate (NaBut) potentiated TNF-induced expression of several natural NF-B-driven promoters. This transcriptional synergism observed between TNF and TSA (or NaBut) required intact B sites in all promoters tested and was biologically relevant as demonstrated by RNase protection on two instances of endogenous NF-B-regulated gene transcription. Importantly, TSA prolonged both TNF-induced DNA-binding activity and the presence of NF-B in the nucleus. We showed that the p65 subunit of NF-B was acetylated in vivo. However, this acetylation was weak, suggesting that other mechanisms could be implicated in the potentiated binding and transactivation activities of NF-B after TNF plus TSA versus TNF treatment. Western blot and immunofluorescence confocal microscopy experiments revealed a delay in the cytoplasmic reappearance of the IB␣ inhibitor that correlated temporally with the prolonged intranuclear binding and presence of NF-B. This delay was due neither to a defect in IB␣ mRNA production nor to a nuclear retention of IB␣ but was rather due to a persistent proteasome-mediated degradation of IB␣. A prolongation of IB kinase activity could explain, at least partially, the delayed IB␣ cytoplasmic reappearance observed in presence of TNF plus TSA.NF-B is a ubiquitously expressed family of transcription factors controlling the expression of numerous genes involved in inflammatory and immune responses and cellular proliferation (reviewed in references 4, 5, 19, and 26). There are five known members of the mammalian NF-B/Rel family: p50 (NF-B1), p52 (NF-B2), p65 (RelA), c-Rel, and RelB. The most abundant form of NF-B is a heterodimer of p50 and p65. In unstimulated cells, NF-B is sequestered in the cytoplasm in an inactive form through interaction with the IB inhibitory proteins (including IB␣, IB␤, and IBε, of which the best studied is IB␣). Upon stimulation of cells by specific inducers, such as the proinflammatory cytokine tumor necrosis factor SF2 (referred to as TNF hereinafter), IB␣ is phosphorylated on two specific serine residues by a large cytoplasmic IB kinase (IKK) complex that consists of the kinase catalytic subunits IKK␣ and IKK␤ and the regulatory subunit NEMO/ IKK␥ (reviewed in references 23 and 26). This phosphorylation marks IB␣ for polyubiquitination by the E3-SCF ␤-TrCP ubiquitin ligase complex, a specific ubiquitin ligase belonging to the SCF (i.e., Skp-1/Cul/Fbox) family, and for degradation by the 26S proteasome (reviewed in reference 5). Degradation of IB␣ allows a rapid and transient translocation of NF-B to the nucleus, where it activates transcription from a wide variety of promoters-including that of its own inhibitor, IB␣. The newly synthesized IB␣ enters the nucleus and removes NF-B from its DNA binding sites and transports it back to the cytoplasm, thereby terminating NF-B-dependent transcription (...

Objective: Corneosurfametry is introduced as a noninvasive quantitative test rating the interaction between surfactants and human stratum corneum. It may be used as a predictive irritancy test. Background: Surfactants present in personal-care products elicit multiple effects on the stratum corneum. With upcoming regulations avoiding animal experiments and ethical considerations for human testing, there is a need for new in vitro methods evaluating irritancy. Design: Corneosurfametry entails collection of cyanoacrylate skin surface strippings and short contact time with surfactants followed by staining samples with toluidine blue and basic fuchsin dyes. Measurements are made by reading the color of samples using reflectance colorimetry. Results: The intensity of color increases with irritancy potential of the surfactant. Results are reproducible, and great differences are noted among a series of diluted shampoos, shower gels and facial cleansing gels. Conclusion: Corneosurfametry is proposed as a rapid in vitro method allowing a predictive grading of surfactants related to irritancy.

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Skin compatibility of anionic surfactants may often but not always be predicted by in vitro tests. For instance, the correlation between in vivo and in vitro data is classically hampered in the presence of magnesium. This ion is known to interfere with in vitro skin irritation predictive tests based on protein denaturation. This study was conducted to compare a recently introduced assay, corneosurfametry, with other in vitro tests including the pH-rise of bovine serum albumin, collagen swelling, and zein solubilization tests. Corneosurfametry entails collection of cyanoacrylate skin surface strippings and short contact time with surfactants, followed by staining samples with toluidine blue and basic fuchsin dyes. Measurements are made by reflectance colorimetry. Data show that irritation potentials predicted by corneosurfametry agree with those obtained by established in vivo and in vitro irritation tests. Moreover, corneosurfametry data are not artificially lowered by addition of magnesium in surfactant solutions. In conclusion, corneosurfametry should be viewed as one of the realistic predictive tests for surfactant irritancy.