Variances in the biological functions of astaxanthin geometric isomers (i.e., all-E, Z) are related to their intestinal absorption, but the mechanism of isomer absorption mediated by transporters remains unclear. Here, models of in vitro cell overexpression, in situ intestinal perfusion, and in vivo mouse inhibition were employed to investigate the impact of cluster of differentiation 36 (CD36) on the absorption of astaxanthin isomers. Cells overexpressing CD36 notably enhanced the uptake of Z-astaxanthin, particularly the 9-Z-isomer (47.76%). The absorption rate and permeability of Z-astaxanthin surpassed that of the all-E-isomer by the in situ model. Furthermore, the addition of the CD36-specific inhibitor sulfo-N-succinimidyl oleate significantly reduced the absorption of Z-astaxanthin in the mouse duodenum and jejunum, especially the 9-Z-isomer (57.66%). Molecular docking and surface plasmon resonance techniques further validated that 9-Z-astaxanthin binds to more amino acids of CD36 with higher affinity and in a fast-binding, fast-dissociating mode, thus favoring transport. Our findings elucidate, for the first time, the mechanism of the CD36-mediated transmembrane transport of astaxanthin geometric isomers.

Objective: To investigate the mechanism of Sulfo-N-succinimidyloleate (SSO) regulating lipid metabolism disorder induced by silicon dioxide (SiO(2)) . Methods: In March 2023, Rat alveolar macrophages NR8383 were cultured in vitro and randomly divided into control group (C), SSO exposure group (SSO), SiO(2) exposure group (SiO(2)) and SiO(2)+SSO exposure group (SiO(2)+SSO). NR8383 cells were exposure separately or jointly by SSO and SiO(2) for 36 h to construct cell models. Immunofluorescence and BODIPY 493/ 503 staining were used to detect cluster of differentiation (CD36) and intracellular lipid levels, the protein expression levels of CD36, liver X receptors (LXR), P-mammalian target of rapamycin (P-mTOR) and cholinephosphotransferase 1 (CHPT1) were detected by Western blot, respectively, and lipid metabolomics was used to screen for different lipid metabolites and enrichment pathways. Single-factor ANOVA was used for multi-group comparison, and LSD test was used for pair-to-group comparison. Results: SiO(2) caused the expression of CD36 and P-mTOR to increase (P=0.012, 0.020), the expression of LXR to decrease (P=0.005), and the intracellular lipid level to increase. After SSO treatment, CD36 expression decreased (P=0.023) and LXR expression increased (P=0.000) in SiO(2)+SSO exposure group compared with SiO(2) exposure group. Metabolomics identified 87 different metabolites in the C group and SiO(2) exposure group, 19 different metabolites in the SiO(2) exposure group and SiO(2)+SSO group, and 5 overlaps of different metabolites in the two comparison groups, they are PS (22∶1/14∶0), DG (O-16∶0/18∶0/0∶0), PGP (i-13∶0/i-20∶0), PC (18∶3/16∶0), and Sphinganine. In addition, the differential metabolites of the two comparison groups were mainly concentrated in the glycerophospholipid metabolism and sphingolipid metabolism pathways. The differential gene CHPT1 in glycerophospholipid metabolic pathway was verified, and the expression of CHPT1 decreased after SiO(2) exposure. Conclusion: SSO may improve SiO(2)-induced lipid metabolism disorders by regulating PS (22∶1/14∶0), DG (O-16∶0/18∶0/0∶0), PGP (i-13∶0/i-20∶0), PC (18∶3/16∶0), SPA, glycerophospholipid metabolism and sphingolipid metabolism pathways.
目的： 探讨磺基-N-琥珀酰亚胺油酸酯（sulfo-N-succinimidyloleate，SSO）调控二氧化硅（silicon dioxide，SiO(2)）诱导的巨噬细胞脂质代谢紊乱的机制。 方法： 于2023年3月，以常规体外培养大鼠肺泡巨噬细胞NR8383，随机分为对照组（C组）、SSO染毒组、SiO(2)染毒组和SiO(2)+SSO染毒组，使用SSO和SiO(2)分别单独或联合染毒NR8383细胞36 h构建细胞模型。免疫荧光和BODIPY 493/503染色分别检测白细胞分化抗原36（cluster of differentiation，CD36）和细胞内脂质的水平，Western blot检测细胞内CD36、肝脏X受体（liver X receptors，LXR）、磷酸化哺乳动物雷帕霉素靶蛋白（P-mammalian target of rapamycin，P-mTOR）、胆碱磷酸转移酶1（cholinephosphotransferase 1，CHPT1）的蛋白表达水平，脂质代谢组学筛选差异脂质代谢物及富集的途径。多组比较采用单因素方差分析，组内两两比较用LSD检验。 结果： SiO(2)染毒导致巨噬细胞CD36、P-mTOR表达增加（P=0.012、0.020），LXR表达降低（P=0.005），细胞内脂质水平升高，给予SSO干预后，与SiO(2)染毒组比较，SiO(2)+SSO染毒组巨噬细胞CD36表达降低（P=0.023），LXR表达升高（P=0.000）。代谢组学筛选出C组和SiO(2)染毒组中有87个差异代谢物，SiO(2)染毒组和SiO(2)+SSO染毒组中有19个差异代谢物，两个组中差异代谢物存在5个交集，分别为PS（22∶1/14∶0）、DG（O-16∶0/18∶0/0∶0）、PGP（i-13∶0/i-20∶0）、PC（18∶3/16∶0）、鞘氨酸（SPA）。两个比较组差异代谢物均主要富集在甘油磷脂代谢和鞘脂代谢通路。对甘油磷脂代谢通路中的差异基因CHPT1进行验证，SiO(2)染毒后导致巨噬细胞CHPT1表达降低（P=0.041）。 结论： SSO可能通过调控PS（22∶1/14∶0）、DG（O-16∶0/18∶0/0∶0）、PGP（i-13∶0/i-20∶0）、PC（18∶3/16∶0）、SPA以及甘油磷脂代谢和鞘脂代谢通路改善SiO(2)诱导的巨噬细胞脂质代谢紊乱。.

Fingolimod is an oral immunomodulatory drug used in the treatment of multiple sclerosis (MS) that may change lipid metabolism. Peroxisome proliferator-activated receptors (PPAR) are transcription factors that regulate lipoprotein metabolism and immune functions and have been implicated in the pathophysiology of MS. CD36 is a scavenger receptor whose transcription is PPAR regulated. The objective of this study was to evaluate whether fingolimod treatment modifies PPAR and CD36 gene expression as part of its action mechanisms. Serum lipoprotein profiles and PPAR and CD36 gene expression levels in peripheral leukocytes were analysed in 17 female MS patients before and at 6 and 12 months after fingolimod treatment initiation. Clinical data during the follow-up period of treatment were obtained. We found that fingolimod treatment increased HDL-Cholesterol and Apolipoprotein E levels and leukocyte PPARγ and CD36 gene expression. No correlations were found between lipid levels and variations in PPARγ and CD36 gene expression. PPARγ and CD36 variations were significantly correlated during therapy and in patients free of relapse and stable disease. Our results suggest that PPARγ and CD36-mediated processes may contribute to the mechanisms of action of fingolimod in MS. Further studies are required to explore the relation of the PPARγ/CD36 pathway to the clinical efficacy of the drug and its involvement in the pathogenesis of the disease.

Targeted cancer therapy with natural compounds is more effective than nontargeted therapy. Nobiletin is a flavonoid derived from citrus peel that has anticancer activity. Cluster of differentiation 36 (CD36) is a member of the class B scavenger receptor family that is involved in importing fatty acids into cells. CD36 plays a role in tumor angiogenesis by binding to its ligand, thrombospondin-1 (TSP-1), and then interacting with transforming growth factor beta 1 (TGFβ1). CD36 is implicated in tumor metastasis through its roles in fatty acid metabolism. This study investigated the molecular mechanisms underlying nobiletin\'s anticancer activity by characterizing its interactions with CD36 as the target molecule. We hypothesize that the anti-angiogenic activity of nobiletin involving its regulation of CD36 via signal transducer and activator of transcription 3 (STAT3) rather than through TSP-1. Gene analysis identified a Gamma interferon activation site (GAS) element in the CD36 gene promoter that acts as a STAT3 binding site, an interaction that was confirmed by ChIP assay. STAT3 interacts with nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), suggesting that nobiletin also acts through the CD36/ (STAT3)/NF-κB signaling axis. Nobiletin inhibited CD36-dependent breast cancer cell migration and invasion as well as CD36-mediated tumor sphere formation. Taken together, these results suggest that nobiletin inhibits cancer stem cells in multiple ways.