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Conjugated Bile Acids Activate Lymphangiogenic Pathways, Induce Chemokine Production and Significantly Alter Cellular Metabolism in Lymphatic Endothelial Cells
Author(s) -
Kumaravel Subhashree,
Singh Sumeet,
Singh Ashlynn,
Roy Sukanya,
Alpini Gianfranco,
Glaser Shan,
Chakraborty Sanjukta
Publication year - 2021
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2021.35.s1.04032
Subject(s) - g protein coupled bile acid receptor , chemokine , receptor , deoxycholic acid , bile acid , calcitriol receptor , angiogenesis , endocrinology , medicine , chemistry , cancer research
Elevated levels of conjugated bile acids (BA) such as taurochenodeoxycholic acid (TCDCA) and taurocholic acid (TCA) are found in serum of patients with chronic inflammatory liver diseases and liver cancers. Increased lymphangiogenesis has been documented in several chronic liver diseases, as lymphatics are integral to the hepatic microcirculation and also plays an important role in early metastasis of liver cancers like hepatocellular and cholangiocarcinoma. High levels of BAs have been shown in metastatic tumor‐bearing LNs compared to naive LNs, however, the effects of BAs on lymphatic endothelial cells (LECs) remain completely undefined. The present study focuses on investigating the effects of TCDCA and TCA on inducing molecular and metabolic changes in LECs. LECs were treated with TCDCA (100 uM) and TCA (100 uM) for 24hrs in presence or absence of specific BA receptor inhibitor (FXR or TGR5: 50uM) and the changes in proliferation, migration, tube formation was determined. Effects of BAs on LEC cellular metabolism was assessed by Seahorse analysis and lactate levels, ATP production and ROS was measured by fluorometric assays. mRNA levels of bile acid receptors‐ FXR, TGR5, VDR as well as receptors for VEGF and FGF, chemokines and chemokine receptors were analyzed by real time quantitative PCR. Inhibitor for TGR5 was used to test the role of TGR5. Our results showed that LECs express the BA receptors FXR, TGR5 and VDR with TGR5 showing highest basal level expression. Both TCDCA and TCA induced significant induction in migration rates as well as increased LEC tube formation. Among the two BA used, TCDCA induced more metabolic changes in LECs than TCA with significant increase in maximal glycolytic capacity as well as basal rate of ATP production. These alterations were abrogated in presence of the TGR5 inhibitor. BAs, also increased levels of Yes‐associated protein (YAP) (associated with increased lymphangiogenesis and tumor metastasis) and several downstream mediators in the LECs. Further, TCDCA elevated several lymphangiogenic molecules such as VEGFR1, VEGFR3, FGFR2 and FGFR4, and other inflammatory chemokines and chemokine receptors that play an important role in LEC immune cell crosstalk such as CCL19, CXCL5, CCR4, CCR5. TCA on the other hand, significantly increased mRNA expression of VEGFR3, MCP1 and CCR4 indicating specific roles for the different BAs on LECs. From these data we conclude that TCDCA and TCA alters morphological and phenotypic characteristics of LECs, induces lymphangiogenesis and promotes inflammatory signaling. We also predict that these activities of BA are initiated through the FXR and TGR5 receptors and targeting these pathways could suppress lymphangiogenesis and progression of inflammation.