Primary open-angle glaucoma (POAG) is often caused by elevated intraocular pressure (IOP), which arises due to increased resistance to aqueous humor outflow (AHO). Aqueous humor flows through Schlemm’s canal (SC), a lymphatic-like vessel encircling the cornea, and via intercellular spaces of ciliary muscle cells. However, the mechanisms underlying increased AHO resistance are poorly understood. Here, we demonstrate that signaling between angiopoietin (Angpt) and the Angpt receptor Tie2, which is critical for SC formation, is also indispensable for maintaining SC integrity during adulthood. Deletion of Angpt1/Angpt2 or Tie2 in adult mice severely impaired SC integrity and transcytosis, leading to elevated IOP, retinal neuron damage, and impairment of retinal ganglion cell function, all hallmarks of POAG in humans. We found that SC integrity is maintained by interconnected and coordinated functions of Angpt-Tie2 signaling, AHO, and Prox1 activity. These functions diminish in the SC during aging, leading to impaired integrity and transcytosis. Intriguingly, Tie2 reactivation using a Tie2 agonistic antibody rescued the POAG phenotype in Angpt1/Angpt2-deficient mice and rejuvenated the SC in aged mice. These results indicate that the Angpt-Tie2 system is essential for SC integrity. The impairment of this system underlies POAG-associated pathogenesis, supporting the possibility that Tie2 agonists could be a therapeutic option for glaucoma.
Jaeryung Kim, Dae-Young Park, Hosung Bae, Do Young Park, Dongkyu Kim, Choong-kun Lee, Sukhyun Song, Tae-Young Chung, Dong Hui Lim, Yoshiaki Kubota, Young-Kwon Hong, Yulong He, Hellmut G. Augustin, Guillermo Oliver, Gou Young Koh
Atherosclerosis is a chronic inflammatory disease, and developing therapies to promote its regression is an important clinical goal. We previously established that atherosclerosis regression is characterized by an overall decrease in plaque macrophages and enrichment in markers of alternatively activated M2 macrophages. We have now investigated the origin and functional requirement for M2 macrophages in regression in normolipidemic mice that received transplants of atherosclerotic aortic segments. We compared plaque regression in WT normolipidemic recipients and those deficient in chemokine receptors necessary to recruit inflammatory Ly6Chi (Ccr2–/– or Cx3cr1–/–) or patrolling Ly6Clo (Ccr5–/–) monocytes. Atherosclerotic plaques transplanted into WT or Ccr5–/– recipients showed reduced macrophage content and increased M2 markers consistent with plaque regression, whereas plaques transplanted into Ccr2–/– or Cx3cr1–/– recipients lacked this regression signature. The requirement of recipient Ly6Chi monocyte recruitment was confirmed in cell trafficking studies. Fate-mapping and single-cell RNA sequencing studies also showed that M2-like macrophages were derived from newly recruited monocytes. Furthermore, we used recipient mice deficient in STAT6 to demonstrate a requirement for this critical component of M2 polarization in atherosclerosis regression. Collectively, these results suggest that continued recruitment of Ly6Chi inflammatory monocytes and their STAT6-dependent polarization to the M2 state are required for resolution of atherosclerotic inflammation and plaque regression.
Karishma Rahman, Yuliya Vengrenyuk, Stephen A. Ramsey, Noemi Rotllan Vila, Natasha M. Girgis, Jianhua Liu, Viktoria Gusarova, Jesper Gromada, Ada Weinstock, Kathryn J. Moore, P’ng Loke, Edward A. Fisher
The mechanisms that promote the generation of new coronary vasculature during cardiac homeostasis and after injury remain a fundamental and clinically important area of study in the cardiovascular field. Recently, it was reported that mesenchymal-to-endothelial transition (MEndoT) contributes to substantial numbers of coronary endothelial cells after myocardial infarction. Therefore, the MEndoT has been proposed as a paradigm mediating neovascularization and is considered a promising therapeutic target in cardiac regeneration. Here, we show that preexisting endothelial cells mainly beget new coronary vessels in the adult mouse heart, with essentially no contribution from other cell sources through cell-lineage transdifferentiation. Genetic-lineage tracing revealed that cardiac fibroblasts expand substantially after injury, but do not contribute to the formation of new coronary blood vessels, indicating no contribution of MEndoT to neovascularization. Moreover, genetic-lineage tracing with a pulse-chase labeling strategy also showed that essentially all new coronary vessels in the injured heart are derived from preexisting endothelial cells, but not from other cell lineages. These data indicate that therapeutic strategies for inducing neovascularization should not be based on targeting presumptive lineage transdifferentiation such as MEndoT. Instead, preexisting endothelial cells appear more likely to be the therapeutic target for promoting neovascularization and driving heart regeneration after injury.
Lingjuan He, Xiuzhen Huang, Onur Kanisicak, Yi Li, Yue Wang, Yan Li, Wenjuan Pu, Qiaozhen Liu, Hui Zhang, Xueying Tian, Huan Zhao, Xiuxiu Liu, Shaohua Zhang, Yu Nie, Shengshou Hu, Xiang Miao, Qing-Dong Wang, Fengchao Wang, Ting Chen, Qingbo Xu, Kathy O. Lui, Jeffery D. Molkentin, Bin Zhou
Capillary malformation–arteriovenous malformation (CM-AVM) is a blood and lymphatic vessel (LV) disorder that is caused by inherited inactivating mutations of the
Philip E. Lapinski, Beth A. Lubeck, Di Chen, Abbas Doosti, Scott D. Zawieja, Michael J. Davis, Philip D. King
Platelets play a critical role in atherogenesis and thrombosis-mediated myocardial ischemia, processes that are accelerated in diabetes. Whether hyperglycemia promotes platelet production and whether enhanced platelet production contributes to enhanced atherothrombosis remains unknown. Here we found that in response to hyperglycemia, neutrophil-derived S100 calcium-binding proteins A8/A9 (S100A8/A9) interact with the receptor for advanced glycation end products (RAGE) on hepatic Kupffer cells, resulting in increased production of IL-6, a pleiotropic cytokine that is implicated in inflammatory thrombocytosis. IL-6 acts on hepatocytes to enhance the production of thrombopoietin, which in turn interacts with its cognate receptor c-MPL on megakaryocytes and bone marrow progenitor cells to promote their expansion and proliferation, resulting in reticulated thrombocytosis. Lowering blood glucose using a sodium-glucose cotransporter 2 inhibitor (dapagliflozin), depleting neutrophils or Kupffer cells, or inhibiting S100A8/A9 binding to RAGE (using paquinimod), all reduced diabetes-induced thrombocytosis. Inhibiting S100A8/A9 also decreased atherogenesis in diabetic mice. Finally, we found that patients with type 2 diabetes have reticulated thrombocytosis that correlates with glycated hemoglobin as well as increased plasma S100A8/A9 levels. These studies provide insights into the mechanisms that regulate platelet production and may aid in the development of strategies to improve on current antiplatelet therapies and to reduce cardiovascular disease risk in diabetes.
Michael J. Kraakman, Man K.S. Lee, Annas Al-Sharea, Dragana Dragoljevic, Tessa J. Barrett, Emilie Montenont, Debapriya Basu, Sarah Heywood, Helene L. Kammoun, Michelle Flynn, Alexandra Whillas, Nordin M.J. Hanssen, Mark A. Febbraio, Erik Westein, Edward A. Fisher, Jaye Chin-Dusting, Mark E. Cooper, Jeffrey S. Berger, Ira J. Goldberg, Prabhakara R. Nagareddy, Andrew J. Murphy
Sarah R. Langley, Karin Willeit, Athanasios Didangelos, Ljubica Perisic Matic, Philipp Skroblin, Javier Barallobre-Barreiro, Mariette Lengquist, Gregor Rungger, Alexander Kapustin, Ludmilla Kedenko, Chris Molenaar, Ruifang Lu, Temo Barwari, Gonca Suna, Xiaoke Yin, Bernhard Iglseder, Bernhard Paulweber, Peter Willeit, Joseph Shalhoub, Gerard Pasterkamp, Alun H. Davies, Claudia Monaco, Ulf Hedin, Catherine M. Shanahan, Johann Willeit, Stefan Kiechl, Manuel Mayr
The major function of the lymphatic system is to drain interstitial fluid from tissue. Functional drainage causes increased fluid flow that triggers lymphatic expansion, which is conceptually similar to hypoxia-triggered angiogenesis. Here, we have identified a mechanotransduction pathway that translates laminar flow–induced shear stress to activation of lymphatic sprouting. While low-rate laminar flow commonly induces the classic shear stress responses in blood endothelial cells and lymphatic endothelial cells (LECs), only LECs display reduced Notch activity and increased sprouting capacity. In response to flow, the plasma membrane calcium channel ORAI1 mediates calcium influx in LECs and activates calmodulin to facilitate a physical interaction between Krüppel-like factor 2 (KLF2), the major regulator of shear responses, and PROX1, the master regulator of lymphatic development. The PROX1/KLF2 complex upregulates the expression of
Dongwon Choi, Eunkyung Park, Eunson Jung, Young Jin Seong, Jaehyuk Yoo, Esak Lee, Mingu Hong, Sunju Lee, Hiroaki Ishida, James Burford, Janos Peti-Peterdi, Ralf H. Adams, Sonal Srikanth, Yousang Gwack, Christopher S. Chen, Hans J. Vogel, Chester J. Koh, Alex K. Wong, Young-Kwon Hong
Microvascular endothelial cells (ECs) are increasingly recognized as organ-specific gatekeepers of their microenvironment. Microvascular ECs instruct neighboring cells in their organ-specific vascular niches through angiocrine factors, which include secreted growth factors (angiokines), extracellular matrix molecules, and transmembrane proteins. However, the molecular regulators that drive organ-specific microvascular transcriptional programs and thereby regulate angiodiversity are largely elusive. In contrast to other ECs, which form a continuous cell layer, liver sinusoidal ECs (LSECs) constitute discontinuous, permeable microvessels. Here, we have shown that the transcription factor GATA4 controls murine LSEC specification and function. LSEC-restricted deletion of
Cyrill Géraud, Philipp-Sebastian Koch, Johanna Zierow, Kay Klapproth, Katrin Busch, Victor Olsavszky, Thomas Leibing, Alexandra Demory, Friederike Ulbrich, Miriam Diett, Sandhya Singh, Carsten Sticht, Katja Breitkopf-Heinlein, Karsten Richter, Sanna-Maria Karppinen, Taina Pihlajaniemi, Bernd Arnold, Hans-Reimer Rodewald, Hellmut G. Augustin, Kai Schledzewski, Sergij Goerdt
We recently demonstrated that selective expression of the Rho GTPase-activating protein ARHGAP42 in smooth muscle cells (SMCs) controls blood pressure by inhibiting RhoA-dependent contractility, providing a mechanism for the blood pressure–associated locus within the
Xue Bai, Kevin D. Mangum, Rachel A. Dee, George A. Stouffer, Craig R. Lee, Akinyemi Oni-Orisan, Cam Patterson, Jonathan C. Schisler, Anthony J. Viera, Joan M. Taylor, Christopher P. Mack
Atherothrombotic vascular disease is often triggered by a distinct type of atherosclerotic lesion that displays features of impaired inflammation resolution, notably a necrotic core and thinning of a protective fibrous cap that overlies the core. A key cause of plaque necrosis is defective clearance of apoptotic cells, or efferocytosis, by lesional macrophages, but the mechanisms underlying defective efferocytosis and its possible links to impaired resolution in atherosclerosis are incompletely understood. Here, we provide evidence that proteolytic cleavage of the macrophage efferocytosis receptor c-Mer tyrosine kinase (MerTK) reduces efferocytosis and promotes plaque necrosis and defective resolution. In human carotid plaques, MerTK cleavage correlated with plaque necrosis and the presence of ischemic symptoms. Moreover, in fat-fed LDL receptor–deficient (
Bishuang Cai, Edward B. Thorp, Amanda C. Doran, Brian E. Sansbury, Mat J.A.P. Daemen, Bernhard Dorweiler, Matthew Spite, Gabrielle Fredman, Ira Tabas