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Oral Corticosteroids
Published in Vineet Relhan, Vijay Kumar Garg, Sneha Ghunawat, Khushbu Mahajan, Comprehensive Textbook on Vitiligo, 2020
Lipocortins (annexins) inhibit the activity of phospholipase A2. Phospholipase A2 releases arachidonic acid from phospholipids for production of prostanoids and leukotrienes, which produces an inflammatory response. Corticosteroids act as anti-inflammatories by stimulating the production of lipocortins. Corticosteroids also inhibit formation of interleukin-1 by inhibiting mRNA. By altering arachidonic acid metabolism and reducing interleukin-1 formation, corticosteroids produce immunosuppressive, anti-inflammatory, and anti-mitogenic effects [4,5].
Atherosclerosis
Published in George Feuer, Felix A. de la Iglesia, Molecular Biochemistry of Human Disease, 2020
George Feuer, Felix A. de la Iglesia
Phospholipases are found in small amounts in membranes and they are relevant to atherosclerosis. Phospholipases can degrade lipoproteins in the blood or in the cell.168,169,519These enzymes play a role in thrombosis through control of the synthesis of prostaglandins and thromboxanes. The action of phospholipase A2 on phospholipid substrates leads to free fatty acids and lysophosphatidic acid. In most naturally occurring phospholipids, unsaturated fatty acids occupy position 2 of the glycerol skeleton which is cleared by phospholipase A2. This enzyme, therefore is able to release arachidonic acid which is the immediate precursor of potent substances such as prostaglandins and thromboxanes. The other product of hydrolysis, lysophosphatide, exerts a detergent action and promotes lysis of membranes.
Initiation of Labor in Women
Published in Gabor Huszar, The Physiology and Biochemistry of the Uterus in Pregnancy and Labor, 2020
M. Linette Casey, Paul C. MacDonald
Since it is believed that the fetal membranes are of signal importance in the Organ Communication System that exists between the fetus and mother, it is imperative to evaluate the possible role of these tissues in the biochemical events that lead to prostaglandin formation. The activity of phospholipase A2, the enzyme that catalyzes the hydrolysis of the ester bond at the sn-2 position of glycerophospholipids, has been demonstrated in human chorioamnion tissue.17 In addition, it has been shown that the concentration of arachidonic acid was greater in chorioamnion tissues obtained before the spontaneous onset of labor than in those obtained after the onset of labor.18 All of these findings15,18 are consistent with the hypothesis that the fetal membranes do, in fact, occupy a central role in the metabolic events that culminate in the initiation of parturition, i.e., events that are involved in the biosynthesis of prostaglandins; and it was these findings, of little more than a decade ago, that spurred the in-depth investigations of the regulation of prostaglandin formation in amnion, chorion, and uterine decidua vera.
Evaluation of anti-inflammatory impact of dexamethasone-loaded PCL-PEG-PCL micelles on endotoxin-induced uveitis in rabbits
Published in Pharmaceutical Development and Technology, 2019
Mitra Alami-Milani, Parvin Zakeri-Milani, Hadi Valizadeh, Shahram Sattari, Sara Salatin, Mitra Jelvehgari
Corticosteroids are the most common medication used to reduce the inflammatory symptoms in uveitis (Behar-Cohen et al. 1997). Among the corticosteroids, dexamethasone (DEX) is one of the most potent; with an anti-inflammatory activity that is thirty-fold greater than that of cortisol and six-fold greater than triamcinolone (Herrero-Vanrell et al. 2011; Bandello et al. 2015). The anti-inflammatory function of corticosteroids has been ascribed to a group of phospholipase A2 inhibitory proteins, conjointly called lipocortin (Wallner et al. 1986). Phospholipase A2 is an enzyme which acts on the cell membrane and releases arachidonic acid from membrane-bound phospholipids (Tamby et al. 1993). Application of DEX up-regulates the synthesis of lipocortin, thereby reducing the production of arachidonic acid metabolites (Lima et al. 2017).
Isozymes inhibited by active site blocking: versatility of calcium indifferent hesperidin binding to phospholipase A2 and its significance
Published in Journal of Receptors and Signal Transduction, 2019
J. Abhithaj, K. G. Arun, C. S. Sharanya, M. Haridas, E. Jayadevi Variyar
The active site of these enzymes has an Asp/His dyad, and a critical concentration of Ca2+ is required for the cleavage of phospholipids. Among the sPLA2, groups I, II, V and X are found in various disease states. sPLA2 is found in the synovial fluid in rheumatoid arthritis. Hence, there is a need for an efficient and selective inhibitor for sPLA2. Certain phospholipid analogs reported as PLA2 inhibitor have shown poor efficacy [9]. Darapladib and Varespladib, the two inhibitors designed against GIIA sPLA2, failed to show therapeutic significance in clinical trials [10]. Plant flavonoids have been found to inhibit PLA2 [11]. Their inhibiting mechanism is not quite well understood. Also, the groups and subgroups of PLA2 complicate the situation. Inhibition of human secretory phospholipase A2 group IIA (PLA2IIA) leads to a decrease in eicosanoids levels and, further into reduced inflammation. Therefore, PLA2IIA is of high pharmacological interest in treatment of chronic diseases. Here, we report the inhibition mechanism of the representatives of PLA2 by a flavonoid derivative, hesperidin, a β-7-rutinoside of hesperitin by in vitro (group IB) and in silico (groups IB, IIA, V and X) experiments.
Metabonomics analysis of serum from rats given long-term and low-level cadmium by ultra-performance liquid chromatography–mass spectrometry
Published in Xenobiotica, 2018
Liyan Hu, Lu Bo, Meiyan Zhang, Siqi Li, Xiujuan Zhao, Changhao Sun
The first pathway is involved in lipid metabolism. PC and phosphatidylethanolamine (PE) are the most abundant phospholipids in all mammalian cell membranes, playing a vital role in the maintenance of proper fluidity and permeability of the membrane (Bou et al., 2010; van der Veen et al., 2017). Phospholipase A2 hydrolyses PC from the sn-2 position to liberate fatty acids and lysoPCs. LysoPC is an important pro-inflammatory and potent atherogenic agent. LysoPC is also found in atherosclerotic lesions at high levels (Matsumoto et al., 2007; Murakami et al., 2011). LysoPE, the degradation product of PE, increased after the massive destruction of membranes (Gonzalez et al., 2012). LPA (P-16:0e/0:0) is an intermediate of ether lipid metabolism. With the rising interest in lipidomics, ether lipids have emerged as potential biomarkers of several diseases, such as neurodegenerative diseases, cancer and metabolic disorders (Dean & Lodhi, 2017; Eisinger et al., 2014; Zhang et al., 2013). In the current study, PC (18:4/18:0) intensity significantly decreased, and the intensities of lysoPC (20:0), lysoPE (20:5/0:0), LPA (P-16:0e/0:0) significantly increased in the high-dose group compared with that in the control group (p < 0.003). The changes indicated that Cd treatment may have adverse effects on lipid metabolism.