interleukin-8 and pirinixic-acid

Peroxisome proliferator-activated receptors (PPARs) are members of a superfamily of nuclear transcription factors. They are involved in mediating numerous physiological effects in humans, including glucose and lipid metabolism. PPARα ligands effectively treat dyslipidemia and have significant antiinflammatory and anti-atherosclerotic activities. These effects and their ligand-dependent activity make nuclear receptors obvious targets for drug design. Here, we present the structure of the human PPARα in complex with WY14643, a member of fibrate class of drug, and a widely used PPAR activator. The crystal structure of this complex suggests that WY14643 induces activation of PPARα in an unusual bipartite mechanism involving conventional direct helix 12 stabilization and an alternative mode that involves a second ligand in the pocket. We present structural observations, molecular dynamics and activity assays that support the importance of the second site in WY14643 action. The unique binding mode of WY14643 reveals a new pattern of nuclear receptor ligand recognition and suggests a novel basis for ligand design, offering clues for improving the binding affinity and selectivity of ligand. We show that binding of WY14643 to PPARα was associated with antiinflammatory disease in a human corneal cell model, suggesting possible applications for PPARα ligands.

Topics: Anti-Inflammatory Agents; Cells, Cultured; Crystallography, X-Ray; Dose-Response Relationship, Drug; Humans; Interleukin-6; Interleukin-8; Kinetics; Models, Molecular; Molecular Dynamics Simulation; PPAR alpha; Protein Conformation; Pyrimidines

  Retinoids have been used for the treatment of skin disorders such as acne, psoriasis, and photoaging. However, despite their beneficial effects, topical retinoids often cause severe local irritation called retinoid dermatitis. We previously developed a novel vitamin A derivative, retinyl retinoate, which induces less irritation and affords excellent tolerance. In this study, we examined whether co-treatment with topical peroxisome proliferator-activated receptor-α (PPARα) agonists (e.g. WY14643) reduce retinoid dermatitis in hairless mouse skin..   The effect of concomitant treatment with a PPARα agonist on retinoid dermatitis in hairless mouse epidermis was evaluated by measuring transepidermal water loss, epidermal histology, and cytokine expression..   Retinyl retinoate induced less severe retinoid dermatitis than retinoic acid. Topical application of a PPARα agonist improved the stratum corneum structure and function, reduced mRNA expression of interleukin (IL)-1α, tumor necrosis factor-α and IL-8, and inhibited ear edema induced by retinoic acid or retinyl retinoate..   Our results indicate that PPARα agonists can potentially be used to improve retinoid dermatitis. We suggest that co-treatment with retinyl retinoate and a PPARα agonist may reduce or prevent detrimental alterations in retinoid-treated skin.

Topics: Administration, Topical; Animals; Cell Differentiation; Cell Proliferation; Dermatitis; Enzyme Inhibitors; Epidermis; Female; Interleukin-1alpha; Interleukin-8; Keratolytic Agents; Liver X Receptors; Mice; Mice, Hairless; Orphan Nuclear Receptors; Palmitic Acid; PPAR alpha; Pyrimidines; Retinoids; Retinyl Esters; RNA, Messenger; Tretinoin; Tumor Necrosis Factor-alpha; Water Loss, Insensible

Chemokine-mediated inflammatory cell infiltration is a hallmark of asthma. We recently demonstrated that glucocorticoids and beta(2)-agonists additively or synergistically suppress tumor necrosis factor-alpha (TNFalpha)-induced production of chemokines eotaxin and interleukin-8 (IL-8), respectively, in human airway smooth muscle (HASM) cells, which may partly explain their combined benefits in asthma. Peroxisome proliferator-activated receptors (PPARs) also modulate inflammatory gene expression. We reported here that the PPARgamma agonists 15-deoxy-Delta(12,14)-PGJ(2) (15d-PGJ(2)) and troglitazone, but not PPARalpha agonist WY-14643, inhibited TNFalpha-induced production of eotaxin and monocyte chemotactic protein-1 (MCP-1) but not IL-8. Eotaxin inhibition was transcriptional and additively enhanced by the glucocorticoid fluticasone and the beta(2)-agonist salmeterol, whereas MCP-1 inhibition was post-transcriptional and additively and synergistically enhanced by fluticasone and salmeterol, respectively. Coimmunoprecipitation revealed that 15d-PGJ(2) induced a protein-protein interaction between PPARgamma and the glucocorticoid receptor (GR) in TNFalpha-treated HASM cells, which was enhanced by fluticasone and salmeterol. 15d-PGJ(2), fluticasone, and salmeterol all inhibited TNFalpha-induced histone H4 acetylation at the eotaxin promoter and NF-kappaB p65 binding to the eotaxin promoter and induced PPARgamma and GR association with the eotaxin promoter, as analyzed by chromatin immunoprecipitation assay. Our data suggest that chemokine expression in HASM cells is differentially regulated by PPARgamma agonists and that the interaction between PPARgamma and GR may be responsible for the additive and synergistic inhibition of chemokine expression by PPARgamma agonists, glucocorticoids, and beta(2)-agonists, particularly the chromatin-dependent suppression of eotaxin gene transcription. The interaction may have wide applications and may provide a potential target for pharmacological and molecular intervention.

Topics: Adrenergic beta-Agonists; Albuterol; Androstadienes; Blotting, Western; Cell Line; Chemokine CCL11; Chemokine CCL2; Chemokines; Chemokines, CC; Chromans; Chromatin; Chromatin Immunoprecipitation; Dose-Response Relationship, Drug; Enzyme-Linked Immunosorbent Assay; Fluticasone; Gene Expression Regulation; Glucocorticoids; Humans; Immunoprecipitation; Interleukin-8; Plasmids; PPAR alpha; PPAR gamma; Promoter Regions, Genetic; Prostaglandin D2; Protein Binding; Pyrimidines; Receptors, Glucocorticoid; Reverse Transcriptase Polymerase Chain Reaction; RNA; Salmeterol Xinafoate; Thiazolidinediones; Transcription, Genetic; Transfection; Troglitazone; Tumor Necrosis Factor-alpha

We have previously reported increased monocyte adhesion to human aortic endothelial cells (HAECs) cultured in 25 mmol/L glucose (HG) compared with normal glucose (NG) (5.5 mmol/L). In this study, we explored mechanisms that contribute to increased monocyte adhesion by elevated glucose.. We found that HAECs cultured in HG have increased production of the chemokine interleukin-6 (IL-6). We examined whether IL-6 directly modulated monocyte adhesion to EC. Inhibition of IL-6 using a neutralizing antibody significantly reduced glucose-mediated monocyte adhesion by 50%, and addition of IL-6 directly to human EC stimulated monocyte adhesion. PPARalpha has been reported to negatively regulate expression of IL-6 in vascular cells, so we examined PPARalpha-associated signaling in EC. A known PPARalpha agonist, Wy14,643, prevented glucose-mediated IL-6 production by EC and reduced glucose-mediated monocyte adhesion by 40%. HG-cultured HAEC had a 50% reduction in expression of PPARalpha compared with control EC. Primary aortic EC isolated from PPARalpha knockout (KO) mice showed increased monocyte adhesion compared with EC isolated from control mice. PPARalpha KO EC also had increased production of IL-6. Finally, we measured IL-6 levels in diabetic db/db mice and found significant 6-fold elevations in IL-6 levels in db/db EC.. These data indicate that IL-6 production is increased in diabetes and contributes to early vascular inflammatory changes. PPARalpha protects EC from glucose-mediated monocyte adhesion, in part through regulation of IL-6 production.

Topics: Animals; Aorta; Cell Adhesion; Diabetes Mellitus, Type 2; Endothelial Cells; Endothelium, Vascular; Glucose; Humans; Interleukin-6; Interleukin-8; Mice; Mice, Inbred C57BL; Mice, Knockout; Mice, Mutant Strains; Monocytes; Pioglitazone; Pyrimidines; Receptors, Cytoplasmic and Nuclear; Recombinant Proteins; Thiazolidinediones; Transcription Factors

Peroxisome proliferator-activated receptors (PPAR) are members of a nuclear receptor superfamily, which were initially described in the context of fatty acid degradation and adipocyte differentiation. In this study we tested the hypothesis that peroxisome proliferator-activated receptor activation also controls inflammation. In an in vitro model with human keratinocytes inflammation was mimicked by irradiation with ultraviolet B light (150 mJ per cm(2)). Activators for PPAR-alpha (WY-14,643, clofibrate) were shown to reverse ultraviolet-B-light-mediated expression of inflammatory cytokines (interleukin-6, interleukin-8). An activator preferentially for PPAR-beta (bezafibrate) did not show prominent effects on interleukin-6 and interleukin-8 expression. The anti-inflammatory action of WY-14,643 on skin cells was further demonstrated by in vivo testings in which topically applied WY-14,643 markedly increased the minimal erythema dose in ultraviolet-B-irradiated skin. Additionally, it was shown that ultraviolet B irradiation led to a decrease of all three peroxisome proliferator-activated receptor subsets at the mRNA level. Also transactivation of peroxisome proliferator response element was attenuated by ultraviolet B irradiation. The downregulation of peroxisome proliferator-activated receptors by ultraviolet B irradiation provides a possible mechanism that leads to exaggerated and prolonged inflammation. This work suggests the possibility of PPAR-alpha activators as novel nonsteroidal anti-inflammatory drugs in the topical treatment of common inflammatory skin diseases such as atopic dermatitis, psoriasis, and photodermatitis.

Topics: Cell Division; Cell Line, Transformed; Dermatitis; DNA Primers; Down-Regulation; Erythema; Gene Expression; Humans; Interleukin-6; Interleukin-8; Keratinocytes; Peroxisome Proliferators; Pyrimidines; Receptors, Cytoplasmic and Nuclear; Response Elements; Skin; Transcription Factors; Ultraviolet Rays