Macakurzin C Derivatives as a Novel Pharmacophore for Pan-Peroxisome Proliferator-Activated Receptor Modulator

The natural flavonoid macakurzin C (1) exhibited adiponectin biosynthesis-inducing activity during adipogenesis in human bone marrow mesenchymal stem cells and its molecular mechanism was directly associated with a pan-peroxisome proliferator-activated receptor (PPAR) modulator affecting all three PPAR subtypes α, γ, and δ. In this study, increases in adiponectin biosynthesisinducing activity by macakurzin C derivatives (2–7) were studied. The most potent adiponectin biosynthesis-inducing compound 6, macakurzin C 3,5-dimethylether, was elucidated as a dual PPARα/γ modulator. Compound 6 may exhibit the most potent activity because of the antagonistic relationship between PPARδ and PPARγ. Docking studies revealed that the O-methylation of macakurzin C to generate compound 6 significantly disrupted PPARδ binding. Compound 6 has therapeutic potential in hypoadiponectinemia-related metabolic diseases.

Specialized Proresolving Mediators for Therapeutic Interventions Targeting Metabolic and Inflammatory Disorders

Uncontrolled inflammation is considered the pathophysiological basis of many prevalent metabolic disorders, such as nonalcoholic fatty liver disease, diabetes, obesity, and neurodegenerative diseases. The inflammatory response is a self-limiting process that produces a superfamily of chemical mediators, called specialized proresolving mediators (SPMs). SPMs include the ω-3-derived family of molecules, such as resolvins, protectins, and maresins, as well as arachidonic acid-derived (ω-6) lipoxins that stimulate and promote resolution of inflammation, clearance of microbes, and alleviation of pain and promote tissue regeneration via novel mechanisms. SPMs function by binding and activating G protein-coupled receptors, such as FPR2/ALX, GPR32, and ERV1, and nuclear orphan receptors, such as RORα. Recently, several studies reported that SPMs have the potential to attenuate lipid metabolism disorders. However, the understanding of pharmacological aspects of SPMs, including tissue-specific biosynthesis, and specific SPM receptors and signaling pathways, is currently limited. Here, we summarize recent advances in the role of SPMs in resolution of inflammatory diseases with metabolic disorders, such as nonalcoholic fatty liver disease and obesity, obtained from preclinical animal studies. In addition, the known SPM receptors and their intracellular signaling are reviewed as targets of resolution of inflammation, and the currently available information on the therapeutic effects of major SPMs for metabolic disorders is summarized.

Bioactive Lipids and Their Derivatives in Biomedical Applications

Lipids, which along with carbohydrates and proteins are among the most important nutrients for the living organism, have a variety of biological functions that can be applied widely in biomedicine. A fatty acid, the most fundamental biological lipid, may be classified by length of its aliphatic chain, and the short-, medium-, and long-chain fatty acids and each have distinct biological activities with therapeutic relevance. For example, short-chain fatty acids have immune regulatory activities and could be useful against autoimmune disease; medium-chain fatty acids generate ketogenic metabolites and may be used to control seizure; and some metabolites oxidized from long-chain fatty acids could be used to treat metabolic disorders. Glycerolipids play important roles in pathological environments, such as those of cancers or metabolic disorders, and thus are regarded as a potential therapeutic target. Phospholipids represent the main building unit of the plasma membrane of cells, and play key roles in cellular signaling. Due to their physical properties, glycerophospholipids are frequently used as pharmaceutical ingredients, in addition to being potential novel drug targets for treating disease. Sphingolipids, which comprise another component of the plasma membrane, have their own distinct biological functions and have been investigated in nanotechnological applications such as drug delivery systems. Saccharolipids, which are derived from bacteria, have endotoxin effects that stimulate the immune system. Chemically modified saccharolipids might be useful for cancer immunotherapy or as vaccine adjuvants. This review will address the important biological function of several key lipids and offer critical insights into their potential therapeutic applications.

Specialized Proresolving Mediators for Therapeutic Interventions Targeting Metabolic and Inflammatory Disorders

Uncontrolled inflammation is considered the pathophysiological basis of many prevalent metabolic disorders, such as nonalcoholic fatty liver disease, diabetes, obesity, and neurodegenerative diseases. The inflammatory response is a self-limiting process that produces a superfamily of chemical mediators, called specialized proresolving mediators (SPMs). SPMs include the ω-3-derived family of molecules, such as resolvins, protectins, and maresins, as well as arachidonic acid-derived (ω-6) lipoxins that stimulate and promote resolution of inflammation, clearance of microbes, and alleviation of pain and promote tissue regeneration via novel mechanisms. SPMs function by binding and activating G protein-coupled receptors, such as FPR2/ALX, GPR32, and ERV1, and nuclear orphan receptors, such as RORα. Recently, several studies reported that SPMs have the potential to attenuate lipid metabolism disorders. However, the understanding of pharmacological aspects of SPMs, including tissue-specific biosynthesis, and specific SPM receptors and signaling pathways, is currently limited. Here, we summarize recent advances in the role of SPMs in resolution of inflammatory diseases with metabolic disorders, such as nonalcoholic fatty liver disease and obesity, obtained from preclinical animal studies. In addition, the known SPM receptors and their intracellular signaling are reviewed as targets of resolution of inflammation, and the currently available information on the therapeutic effects of major SPMs for metabolic disorders is summarized.

Bioactive Lipids and Their Derivatives in Biomedical Applications

Lipids, which along with carbohydrates and proteins are among the most important nutrients for the living organism, have a variety of biological functions that can be applied widely in biomedicine. A fatty acid, the most fundamental biological lipid, may be classified by length of its aliphatic chain, and the short-, medium-, and long-chain fatty acids and each have distinct biological activities with therapeutic relevance. For example, short-chain fatty acids have immune regulatory activities and could be useful against autoimmune disease; medium-chain fatty acids generate ketogenic metabolites and may be used to control seizure; and some metabolites oxidized from long-chain fatty acids could be used to treat metabolic disorders. Glycerolipids play important roles in pathological environments, such as those of cancers or metabolic disorders, and thus are regarded as a potential therapeutic target. Phospholipids represent the main building unit of the plasma membrane of cells, and play key roles in cellular signaling. Due to their physical properties, glycerophospholipids are frequently used as pharmaceutical ingredients, in addition to being potential novel drug targets for treating disease. Sphingolipids, which comprise another component of the plasma membrane, have their own distinct biological functions and have been investigated in nanotechnological applications such as drug delivery systems. Saccharolipids, which are derived from bacteria, have endotoxin effects that stimulate the immune system. Chemically modified saccharolipids might be useful for cancer immunotherapy or as vaccine adjuvants. This review will address the important biological function of several key lipids and offer critical insights into their potential therapeutic applications.

Diallyl Biphenyl-Type Neolignans Have a Pharmacophore of PPARα/γ Dual Modulators

Adiponectin secretion-promoting compounds have therapeutic potentials in human metabolic diseases. Diallyl biphenyl-type neolignan compounds, magnolol, honokiol, and 4-O-methylhonokiol, from a Magnolia officinalis extract were screened as adiponectin-secretion promoting compounds in the adipogenic differentiation model of human bone marrow mesenchymal stem cells (hBM-MSCs). In a target identification study, magnolol, honokiol, and 4-O-methylhonokiol were elucidated as PPARα and PPARγ dual modulators. Diallyl biphenyl-type neolignans affected the transcription of lipid metabolism-associated genes in a different way compared to those of specific PPAR ligands. The diallyl biphenyl-type neolignan structure provides a novel pharmacophore of PPARα/γ dual modulators, which may have unique therapeutic potentials in diverse metabolic diseases.

IL-1 Receptor Antagonist Reduced Chemical-Induced Keratinocyte Apoptosis through Antagonism to IL-1α/IL-1β

Extracellular interleukin 1 alpha (IL-1α) released from keratinocytes is one of the endpoints for in vitro assessments of skin irritancy. Although cells dying via primary skin irritation undergo apoptosis as well as necrosis, IL-1α is not released in apoptotic cells. On the other hand, active secretion has been identified in interleukin-1 receptor antagonist (IL-1ra), which was discovered to be a common, upregulated, differentially-expressed gene in a microarray analysis performed with keratinocytes treated using cytotoxic doses of chemicals. This study examined whether and how IL-1ra, particularly extracellularly released IL-1ra, was involved in chemically-induced keratinocyte cytotoxicity and skin irritation. Primary cultured normal adult skin keratinocytes were treated with cytotoxic doses of chemicals (hydroquinone, retinoic acid, sodium lauryl sulfate, or urshiol) with or without recombinant IL-1ra treatment. Mouse skin was administered irritant concentrations of hydroquinone or retinoic acid. IL-1ra (mRNA and/or intracellular/extracellularly released protein) levels increased in the chemically treated cultured keratinocytes with IL-1α and IL-1β mRNAs and in the chemically exposed epidermis of the mouse skin. Recombinant IL-1ra treatment significantly reduced the chemically-induced apoptotic death and intracellular/extracellularly released IL-1α and IL-1β in keratinocytes. Collectively, extracellular IL-1ra released from keratinocytes could be a compensatory mechanism to reduce the chemically-induced keratinocyte apoptosis by antagonism to IL-1α and IL-1β, suggesting potential applications to predict skin irritation.

Establishment of Immortalized Primary Human Foreskin Keratinocytes and Their Application to Toxicity Assessment and Three Dimensional Skin Culture Construction

In spite of frequent usage of primary human foreskin keratinocytes (HFKs) in the study of skin biology, senescence-induced blockage of in vitro proliferation has been a big hurdle for their effective utilization. In order to overcome this passage limitation, we first isolated ten HFK lines from circumcision patients and successfully immortalized four of them via a retroviral transduction of high-risk human papillomavirus (HPV) E6 and E7 oncogenes. We confirmed expression of a keratinocyte marker protein, keratin 14 and two viral oncoproteins in these immortalized HFKs. We also observed their robust responsiveness to various exogenous stimuli, which was evidenced by increased mRNA expression of epithelial differentiation markers and pro-inflammatory genes in response to three reactive chemicals. In addition, their applicability to cytotoxicity assessment turned out to be comparable to that of HaCaT cells. Finally, we confirmed their differentiation capacity by construction of well-stratified three dimensional skin cultures. These newly established immortalized HFKs will be valuable tools not only for generation of in vitro skin disease models but also for prediction of potential toxicities of various cosmetic chemicals.

Keratinocytic Vascular Endothelial Growth Factor as a Novel Biomarker for Pathological Skin Condition

Skin is an emerging target tissue in pharmaceutical and cosmetic science. Safety assessment for dermal toxicity is a critical step for development of topically applicable pharmaceutical agents and ingredients in cosmetics. Urgent needs exist to set up toxicity testing methods for dermal safety, and identification of novel biomarkers for pathological cutaneous alteration is highly required. Here we will discuss if vascular endothelial growth factor (VEGF) has a potential as a biomarker for dermal impairment. Experimental and clinical evidences for induction of keratinocytic VEGF under pathological conditions will be reviewed.

A Cannabinoid Receptor Agonist N-Arachidonoyl Dopamine Inhibits Adipocyte Differentiation in Human Mesenchymal Stem Cells

Endocannabinoids can affect multiple cellular targets, such as cannabinoid (CB) receptors, transient receptor potential cation channel, subfamily V, member 1 (TRPV1) and peroxisome proliferator-activated receptor gamma (PPARgamma). The stimuli to induce adipocyte differentiation in hBM-MSCs increase the gene transcription of the CB1 receptor, TRPV1 and PPARgamma. In this study, the effects of three endocannabinoids, N-arachidonoyl ethanolamine (AEA), N-arachidonoyl dopamine (NADA) and 2-arachidonoyl glycerol (2-AG), on adipogenesis in hBM-MSCs were evaluated. The adipocyte differentiation was promoted by AEA whereas inhibited by NADA. No change was observed by the treatment of non-cytotoxic concentrations of 2-AG. The difference between AEA and NADA in the regulation of adipogenesis is associated with their effects on PPARgamma transactivation. AEA can directly activate PPARgamma. The effect of AEA on PPARgamma in hBM-MSCs may prevail over that on the CB1 receptor mediated signal transduction, giving rise to the AEA-induced promotion of adipogenesis. In contrast, NADA had no effect on the PPARgamma activity in the PPARgamma transactivation assay. The inhibitory effect of NADA on adipogenesis in hBM-MSCs was reversed not by capsazepine, a TRPV1 antagonist, but by rimonabant, a CB1 antagonist/inverse agonist. Rimonabant by itself promoted adipogenesis in hBM-MSCs, which may be interpreted as the result of the inverse agonism of the CB1 receptor. This result suggests that the constantly active CB1 receptor may contribute to suppress the adipocyte differentiation of hBM-MSCs. Therefore, the selective CB1 agonists that are unable to affect cellular PPARgamma activity inhibit adipogenesis in hBM-MSCs.

miR-526b targets 3' UTR of MMP1 mRNA

Regulation of matrix metalloproteinases (MMPs) is important for many physiological processes involving cancers, inflammation, tissue remodeling and skin aging. Here, we report the novel finding that the expression of MMP1 mRNA is downregulated by the overexpression of miR-526b which is a member of chromosome 19 microRNA cluster (C19MC). Our analysis using reporter constructs containing the 3' untranslated region (3' UTR) of MMP1 and its mutant form showed that the region from 377-383 in the 3' UTR of MMP1 is critical for targeting by miR-526b. In addition, the expression pattern of miR-526b and MMP1 mRNA showed reverse relation between adult dermal and neonatal fibroblasts. We show for the first time that miR-526b, an miRNA belonging to C19MC, can target the 377-383 region of the MMP1 3' UTR.

Three New Single Nucleotide Polymorphisms Identified by a Genome-Wide Association Study in Korean Patients with Vitiligo

Genetic susceptibility is involved in the pathogenesis of vitiligo. Association studies with a whole genome-based approach instead of a single or a few candidate genes may be useful for discovering new susceptible genes. Although the etiology of non-segmental and segmental types is different, the association between gene polymorphisms and vitiligo has been reported, without defining types or in non-segmental type. Whole genome-based single nucleotide polymorphisms (SNPs) were examined in patients with non-segmental and segmental types of vitiligo using the Affymetrix GeneChip 500K mapping array, and 10 functional classes of significant SNPs were selected. Genotyping and data analysis of selected 10 SNPs was performed using real-time PCR. Genotype and allele frequencies were significantly different between both types of vitiligo and three of the target SNPs, DNAH5 (rs2277046), STRN3 (rs2273171), and KIAA1005 (rs3213758). A stronger association was suggested between the mutation in KIAA1005 (rs3213758) and the segmental type compared to the non-segmental type of vitiligo. DNAH5 (rs2277046), STRN3 (rs2273171), and KIAA1005 (rs3213758) may be new vitiligo-related SNPs in Korean patients, either non-segmental or segmental type.