Browsing by Subject "Retinoid"

Now showing 1 - 3 of 3
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    Lysosomal Acid Lipase Hydrolyzes Retinyl Ester and Affects Retinoid Turnover
    (American Society for Biochemistry & Molecular Biology, 2016-08-19) Grumet, Lukas; Eichmann, Thomas O.; Taschler, Ulrike; Zierler, Kathrin A.; Leopold, Christina; Moustafa, Tarek; Radovic, Branislav; Romauch, Matthias; Yan, Cong; Du, Hong; Haemmerle, Guenter; Zechner, Rudolf; Fickert, Peter; Kratky, Dagmar; Zimmermann, Robert; Lass, Achim; Department of Pathology and Laboratory Medicine, IU School of Medicine
    Lysosomal acid lipase (LAL) is essential for the clearance of endocytosed cholesteryl ester and triglyceride-rich chylomicron remnants. Humans and mice with defective or absent LAL activity accumulate large amounts of cholesteryl esters and triglycerides in multiple tissues. Although chylomicrons also contain retinyl esters (REs), a role of LAL in the clearance of endocytosed REs has not been reported. In this study, we found that murine LAL exhibits RE hydrolase activity. Pharmacological inhibition of LAL in the human hepatocyte cell line HepG2, incubated with chylomicrons, led to increased accumulation of REs in endosomal/lysosomal fractions. Furthermore, pharmacological inhibition or genetic ablation of LAL in murine liver largely reduced in vitro acid RE hydrolase activity. Interestingly, LAL-deficient mice exhibited increased RE content in the duodenum and jejunum but decreased RE content in the liver. Furthermore, LAL-deficient mice challenged with RE gavage exhibited largely reduced post-prandial circulating RE content, indicating that LAL is required for efficient nutritional vitamin A availability. In summary, our results indicate that LAL is the major acid RE hydrolase and required for functional retinoid homeostasis.
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    Lysosome-mediated degradation of a distinct pool of lipid droplets during hepatic stellate cell activation
    (American Society for Biochemistry and Molecular Biology, 2017-07-28) Tuohetahuntila, Maidina; Molenaar, Martijn R.; Spee, Bart; Brouwers, Jos F.; Wubbolts, Richard; Houweling, Martin; Yan, Cong; Du, Hong; VanderVen, Brian C.; Vaandrager, Arie B.; Helms, J. Bernd; Medicine, School of Medicine
    Activation of hepatic stellate cells (HSCs) is a critical step in the development of liver fibrosis. During activation, HSCs lose their lipid droplets (LDs) containing triacylglycerols (TAGs), cholesteryl esters, and retinyl esters (REs). We previously provided evidence for the presence of two distinct LD pools, a preexisting and a dynamic LD pool. Here we investigate the mechanisms of neutral lipid metabolism in the preexisting LD pool. To investigate the involvement of lysosomal degradation of neutral lipids, we studied the effect of lalistat, a specific lysosomal acid lipase (LAL/Lipa) inhibitor on LD degradation in HSCs during activation in vitro The LAL inhibitor increased the levels of TAG, cholesteryl ester, and RE in both rat and mouse HSCs. Lalistat was less potent in inhibiting the degradation of newly synthesized TAG species as compared with a more general lipase inhibitor orlistat. Lalistat also induced the presence of RE-containing LDs in an acidic compartment. However, targeted deletion of the Lipa gene in mice decreased the liver levels of RE, most likely as the result of a gradual disappearance of HSCs in livers of Lipa-/- mice. Lalistat partially inhibited the induction of activation marker α-smooth muscle actin (α-SMA) in rat and mouse HSCs. Our data suggest that LAL/Lipa is involved in the degradation of a specific preexisting pool of LDs and that inhibition of this pathway attenuates HSC activation.
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    Tazarotene 0.045% Lotion for Moderate-to-Severe Acne in Male and Female Participants: A Phase II Post-hoc Analysis
    (Matrix Medical Communications, 2021-04) Baldwin, Hilary E.; Green, Lawrence J.; Kircik, Leon; Guenin, Eric Pierre; Loncaric Forest, Anya; Pillai, Radhakrishnan; Dermatology, School of Medicine
    BACKGROUND: In a Phase II study, tazarotene 0.045% lotion was statistically superior to vehicle and comparable to tazarotene 0.1% cream in reducing acne lesions, with fewer treatment-related adverse events (TEAEs) than the cream. OBJECTIVE: We analyzed data from the aforementioned study post-hoc to evaluate the effects of sex on treatment outcomes. METHODS: Participants aged 12 years or older with moderate-to-severe acne were randomized to tazarotene (0.045% lotion or 0.1% cream) or vehicle (lotion or cream) for 12 weeks of double-blind treatment. Outcomes analyzed in male and female subgroups included changes from baseline in inflammatory/noninflammatory lesions and TEAEs. RESULTS: In the intent-to-treat population (94 males and 116 females), reductions in lesion count were greater with tazarotene (lotion or cream) than with vehicle. In participants receiving tazarotene 0.045% lotion, the least-squares mean percent changes from baseline to Week 12 were greater in females than males, but the differences were not statistically significant (inflammatory [-70.3% vs. -56.2%]; noninflammatory [-60.0% vs. -53.2%]). In both females and males, the TEAE incidence was lower with tazarotene 0.045% lotion than 0.1% cream. CONCLUSION: Tazarotene 0.045% lotion substantially reduced acne lesions in both female and male participants. This newest tazarotene formulation might benefit patients who cannot tolerate older formulations or other topical retinoids. Given the relatively small size of this study, however, the results of this post-hoc analysis are intended to be exploratory in nature.