Akerstrom, V. L. | bioRxiv Science

bioRxiv2025

GLP-1R Agonism Directly Improves the Pumping Capacity of Murine Collecting Lymphatic Vessels

BackgroundGlucagon-like peptide-1 receptor (GLP-1R) agonists have recently been suggested as effective therapies to treat or reduce the risk of developing secondary lymphedema in patients with obesity; however, it is unknown whether the observed improvement in lymphatic function is solely due to weight loss-associated systemic benefits or in synergy with a lymphatic-specific effect of these pharmacological therapies. MethodsWe assessed the expression and localization GLP-1Rs in and around the lymphatic vasculature by single-cell RNA sequencing and fluorescence confocal microscopy. Using pressure myography we evaluated the direct effects of GLP-1R agonist, semaglutide, on modulating the contractile activity of lymphatic vessels from healthy wild-type (WT) mice, as well as lymphatics from diet-induced obese (DIO) WT mice, and hypercholesterolemic ApoE KO mice. ResultsExpression of Glp1r (encoding GLP-1Rs) was detected solely in LECs and was highly enriched in LECs from collecting lymphatics but absent in LECs from capillary regions. Pharmacological activation of GLP-1Rs using semaglutide led to robust vasodilation and an increase in the pumping capacity of isolated collecting lymphatics from WT, DIO, and ApoE KO mice. Compared to WT controls, lymphatics from ApoE KO mice displayed significant contractile dysfunction, which was restored with semaglutide. The GLP-1R-mediated response was in part facilitated by nitric oxide (NO), NADPH oxidase-mediated reactive oxygen species (ROS), and potentially vasodilatory prostanoids. ConclusionsOur results revealed a direct, beneficial effect of GLP-1R agonism on lymphatic pumping capacity mediated by robust vasodilation, allowing lymphatics to accommodate larger fluid volumes, while maintaining strong and highly efficient contractions. Our observations implicated NO, ROS, and potentially vasodilatory prostanoids in the underlying mechanism; however, additional signaling components remain to be elucidated. These findings support recent clinical reports and further suggest that GLP-1R agonism could be an effective therapy for improving lymphatic contractile function in secondary lymphedema.

physiology↗

bioRxiv2024

TRPV4-Expressing Tissue-Resident Macrophages Regulate the Function of Collecting Lymphatic Vessels via Thromboxane A2 Receptors in Lymphatic Muscle Cells

RationaleTRPV4 channels are critical regulators of blood vascular function and have been shown to be dysregulated in many disease conditions in association with inflammation and tissue fibrosis. These are key features in the pathophysiology of lymphatic system diseases, including lymphedema and lipedema; however, the role of TRPV4 channels in the lymphatic system remains largely unexplored. TRPV4 channels are calcium permeable, non-selective cation channels that are activated by diverse stimuli, including shear stress, stretch, temperature, and cell metabolites, which may regulate lymphatic contractile function. ObjectiveTo characterize the expression of TRPV4 channels in collecting lymphatic vessels and to determine the extent to which these channels regulate the contractile function of lymphatics. Methods and ResultsPressure myography on intact, isolated, and cannulated lymphatic vessels showed that pharmacological activation of TRPV4 channels with GSK1016790A (GSK101) led to contractile dysregulation. The response to GSK101 was multiphasic and included, 1) initial robust constriction that was sustained for [≥]1 minute and in some instances remained for [≥]4 minutes; and 2) subsequent vasodilation and partial or complete inhibition of lymphatic contractions associated with release of nitric oxide. The functional response to activation of TRPV4 channels displayed differences across lymphatics from four anatomical regions, but these differences were consistent across different species (mouse, rat, and non-human primate). Importantly, similar responses were observed following activation of TRPV4 channels in arterioles. The initial and sustained constriction was prevented with the COX inhibitor, indomethacin. We generated a controlled and spatially defined single-cell RNA sequencing (scRNAseq) dataset from intact and microdissected collecting lymphatic vessels. Our data uncovered a subset of macrophages displaying the highest expression of Trpv4 compared to other cell types within and surrounding the lymphatic vessel wall. These macrophages displayed a transcriptomic profile consistent with that of tissue-resident macrophages (TRMs), including differential expression of Lyve1, Cd163, Folr2, Mrc1, Ccl8, Apoe, Cd209f, Cd209d, and Cd209g; and at least half of these macrophages also expressed Timd4. This subset of macrophages also highly expressed Txa2s, which encodes the thromboxane A2 (TXA2) synthase. Inhibition of TXA2 receptors (TXA2Rs) prevented TRPV4-mediated contractile dysregulation. TXA2R activation on LMCs caused an increase in mobilization of calcium from intracellular stores through Ip3 receptors which promoted store operated calcium entry and vasoconstriction. ConclusionsClinical studies have linked cancer-related lymphedema with an increased infiltration of macrophages. While these macrophages have known anti-inflammatory and pro-lymphangiogenic roles, as well as promote tissue repair, our results point to detrimental effects to the pumping capacity of collecting lymphatic vessels mediated by activation of TRPV4 channels in macrophages. Pharmacological targeting of TRPV4 channels in LYVE1-expressing macrophages or pharmacological targeting of TXA2Rs may offer novel therapeutic strategies to improve lymphatic pumping function and lymph transport in lymphedema. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=101 SRC="FIGDIR/small/595189v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@1ce67fforg.highwire.dtl.DTLVardef@dd1beorg.highwire.dtl.DTLVardef@1454c78org.highwire.dtl.DTLVardef@9f76a1_HPS_FORMAT_FIGEXP M_FIG C_FIG

physiology↗