Vascular biology
Abstract
Complement activation is a relevant driver in the pathomechanisms of vasculitis. The involved proteins in the interaction between endothelia, complement and platelets in these conditions are only partially understood. Thrombospondin-1 (TSP-1), found in platelet α-granules and released from activated endothelial cells, interacts with factor H (FH) and von Willebrand factor (vWF). However, direct regulatory interaction with the complement cascade has not yet been described. We could show that TSP-1 is a potent, FH-independent inhibitor of the alternative complement pathway. TSP-1 binds to complement proteins, inhibits cleavage of C3 and C5 and the formation of the membrane attack complex. Complement-regulatory function is validated in blood samples from patients with primary complement defects. Physiological relevance of TSP-1 is demonstrated in ANCA-associated vasculitis (AAV) patients by significantly enhanced TSP-1 staining in glomerular lesions and increased complement activity and NETosis following TSP-1 deficiency in an in vitro and in vivo model of AAV. The newly described complement-inhibiting function of TSP-1 represents an important mechanism in the interaction of endothelia and complement. In particular, the interplay between released TSP-1 and the complement system locally, especially on surfaces, influences the balance between complement activation and inhibition and may be relevant in various vascular diseases.
Authors
Swagata Konwar, Sophie Schroda, Manuel Rogg, Jessika Kleindienst, Eva L. Decker, Martin Pohl, Barbara Zieger, Jens Peter Panse, Hong Wang, Robert Grosse, Christoph Schell, Sabine Vidal, Xiaobo Liu, Christian Gorzelanny, Todor Tschongov, Karsten Häffner
Abstract
Patients with systemic lupus erythematosus (SLE) are photosensitive, developing skin inflammation with even ambient ultraviolet radiation (UVR), and this cutaneous photosensitivity can be associated with UVR-induced flares of systemic disease, which can involve increased autoantibodies and further end organ injury. Mechanistic insight into the link between the skin responses and autoimmunity is limited. Signals from skin are transmitted directly to the immune system via lymphatic vessels, and here we show evidence for potentiation of UVR-induced lymphatic flow dysfunction in SLE patients and murine models. Improving lymphatic flow by manual lymphatic drainage (MLD) or with a transgenic model with increased lymphatic vessels reduces both cutaneous inflammation and lymph node B and T cell responses, and long term MLD reduces splenomegaly and titers of a number of autoantibodies. Mechanistically, improved flow restrains B cell responses in part by stimulating a lymph node fibroblastic reticular cell-monocyte axis. Our results point to lymphatic modulation of lymph node stromal function as a link between photosensitive skin responses and autoimmunity and as a therapeutic target in lupus, provide insight into mechanisms by which the skin state regulates draining lymph node function, and suggest the possibility of MLD as an accessible and cost-effective adjunct to add to ongoing medical therapies for lupus and related diseases.
Authors
Mir J. Howlader, William G. Ambler, Madhavi Latha S. Chalasani, Aahna Rathod, Ethan S. Seltzer, Ji Hyun Sim, Jinyeon Shin, Noa Schwartz, William D. Shipman III, Dragos C. Dasoveanu, Camila B. Carballo, Ecem Sevim, Salma Siddique, Yurii Chinenov, Scott A. Rodeo, Doruk Erkan, Raghu P. Kataru, Babak J. Mehrara, Theresa T. Lu
Abstract
Aortic aneurysm is a high-risk cardiovascular disease without effective cure. Vascular Smooth Muscle Cell (VSMC) phenotypic switching is a key step in the pathogenesis of aortic aneurysm. Here, we revealed the role of histidine triad nucleotide-binding protein 1 (HINT1) in aortic aneurysm. HINT1 was upregulated both in aortic tissue from patients with aortic aneurysm and Ang II-induced aortic aneurysm mice. VSMC-specific HINT1 deletion alleviated aortic aneurysm via preventing VSMC phenotypic switching. With the stimulation of pathological factors, the increased nuclear translocation of HINT1 mediated by nucleoporin 98 (Nup98) promoted the interaction between HINT1 and transcription factor AP-2 alpha (TFAP2A) and further triggered the transcription of integrin alpha 6 (ITGA6) mediated by TFAP2A, and consequently activated the downstream focal adhesion kinase (FAK)/STAT3 signal pathway, leading to aggravation of VSMC phenotypic switching and aortic aneurysm. Importantly, Defactinib treatment was demonstrated to limit aortic aneurysm development by inhibiting the FAK signal pathway. Thus, HINT1/ITGA6/FAK axis emerges as potential therapeutic strategies in aortic aneurysm.
Authors
Yan Zhang, Wencheng Wu, Xuehui Yang, Shanshan Luo, Xiaoqian Wang, Qiang Da, Ke Yan, Lulu Hu, Shixiu Sun, Xiaolong Du, Xiaoqiang Li, Zhijian Han, Feng Chen, Aihua Gu, Liansheng Wang, Zhiren Zhang, Bo Yu, Chenghui Yan, Yaling Han, Yi Han, Liping Xie, Yong Ji
Abstract
Mitochondrial dysfunction fuels vascular inflammation and atherosclerosis. Mitochondrial calcium uptake 1 (MICU1) maintains mitochondrial Ca2+ homeostasis. However, the role of MICU1 in vascular inflammation and atherosclerosis remains unknown. Here, we report that endothelial MICU1 prevents vascular inflammation and atherosclerosis by maintaining mitochondrial homeostasis. We observed that vascular inflammation was aggravated in endothelial cell–specific Micu1 knockout mice (Micu1ECKO) and attenuated in endothelial cell–specific Micu1 transgenic mice (Micu1ECTg). Furthermore, hypercholesterolemic Micu1ECKO mice also showed accelerated development of atherosclerosis, while Micu1ECTg mice were protected against atherosclerosis. Mechanistically, MICU1 depletion increased mitochondrial Ca2+ influx, thereby decreasing the expression of the mitochondrial deacetylase sirtuin 3 (SIRT3) and the ensuing deacetylation of superoxide dismutase 2 (SOD2), leading to the burst of mitochondrial reactive oxygen species (mROS). Of clinical relevance, we observed decreased MICU1 expression in the endothelial layer covering human atherosclerotic plaques and in human aortic endothelial cells exposed to serum from patients with coronary artery diseases (CAD). Two-sample Wald ratio Mendelian randomization further revealed that increased expression of MICU1 was associated with decreased risk of CAD and coronary artery bypass grafting (CABG). Our findings support MICU1 as an endogenous endothelial resilience factor that protects against vascular inflammation and atherosclerosis by maintaining mitochondrial Ca2+ homeostasis.
Authors
Lu Sun, Ruixue Leng, Monan Liu, Meiming Su, Qingze He, Zhidan Zhang, Zhenghong Liu, Zhihua Wang, Hui Jiang, Li Wang, Shuai Guo, Yiming Xu, Yuqing Huo, Clint L. Miller, Maciej Banach, Yu Huang, Paul C. Evans, Jaroslav Pelisek, Giovanni G. Camici, Bradford C. Berk, Stefan Offermanns, Junbo Ge, Suowen Xu, Jianping Weng
Abstract
Red blood cells (RBCs) induce endothelial dysfunction in type 2 diabetes (T2D), but the mechanism by which RBCs communicate with the vessel is unknown. This study tested the hypothesis that extracellular vesicles (EVs) secreted by RBCs act as mediators of endothelial dysfunction in T2D. Despite a lower production of EVs derived from RBCs of T2D patients (T2D RBC-EVs), their uptake by endothelial cells was greater than that of EVs derived from RBCs of healthy individuals (H RBC-EVs). T2D RBC-EVs impaired endothelium-dependent relaxation and this effect was attenuated following inhibition of arginase in EVs. Inhibition of vascular arginase or oxidative stress also attenuated endothelial dysfunction induced by T2D RBC-EVs. Arginase-1 was detected in RBC-derived EVs, and arginase-1 and oxidative stress were increased in endothelial cells following co-incubation with T2D RBC-EVs. T2D RBC-EVs also increased arginase-1 protein in endothelial cells following mRNA silencing and in the endothelium of aortas from endothelial cell arginase 1 knockout mice. It is concluded that T2D-RBCs induce endothelial dysfunction through increased uptake of EVs that transfer arginase-1 from RBCs to the endothelium to induce oxidative stress and endothelial dysfunction. These results shed important light on the mechanism underlying endothelial injury mediated by RBCs in T2D.
Authors
Aida Collado, Rawan Humoud, Eftychia Kontidou, Maria Eldh, Jasmin Swaich, Allan Zhao, Jiangning Yang, Tong Jiao, Elena Domingo, Emelie Carlestål, Ali Mahdi, John Tengbom, Ákos Végvári, Qiaolin Deng, Michael Alvarsson, Susanne Gabrielsson, Per Eriksson, Zhichao Zhou, John Pernow
Abstract
Aortic aneurysms are potentially fatal focal enlargements of the aortic lumen; the disease burden disease is increasing as the human population ages. Pathological oxidative stress is implicated in development of aortic aneurysms. We pursued a chemogenetic approach to create an animal model of aortic aneurysm formation using a transgenic mouse line DAAO-TGTie2 that expresses yeast D-amino acid oxidase (DAAO) under control of the endothelial Tie2 promoter. In DAAO-TGTie2 mice, DAAO generates the reactive oxygen species hydrogen peroxide (H2O2) in endothelial cells only when provided with D-amino acids. When DAAO-TGTie2 mice are chronically fed D-alanine, the animals become hypertensive and develop abdominal but not thoracic aortic aneurysms. Generation of H2O2 in the endothelium leads to oxidative stress throughout the vascular wall. Proteomic analyses indicate that the oxidant-modulated protein kinase JNK1 is dephosphorylated by the phophoprotein phosphatase DUSP3 in abdominal but not thoracic aorta, causing activation of KLF4-dependent transcriptional pathways that trigger phenotypic switching and aneurysm formation. Pharmacological DUSP3 inhibition completely blocks aneurysm formation caused by chemogenetic oxidative stress. These studies establish that regional differences in oxidant-modulated signaling pathways lead to differential disease progression in discrete vascular beds, and identify DUSP3 as a potential pharmacological target for the treatment of aortic aneurysms.
Authors
Apabrita Ayan Das, Markus Waldeck-Weiermair, Shambhu Yadav, Fotios Spyropoulos, Arvind Pandey, Tanoy Dutta, Taylor A. Covington, Thomas Michel
Abstract
Osteogenic transdifferentiation of vascular smooth muscle cells (VSMCs) has been recognized as the principal mechanism underlying vascular calcification (VC). Runt-related transcription factor 2 (RUNX2) in VSMCs plays a pivotal role because it constitutes an essential osteogenic transcription factor for bone formation. As a key DNA demethylation enzyme, ten-eleven translocation 2 (TET2) is crucial in maintaining the VSMC phenotype. However, whether TET2 involves in VC progression remains elusive. Here we identified a substantial downregulation of TET2 in calcified human and mouse arteries, as well as human primary VSMCs. In vitro gain- and loss-of function experiments demonstrated TET2 regulated VC. Subsequently, in vivo knockdown of TET2 significantly exacerbated VC in both vitamin D3 and adenine-diet-induced chronic kidney disease (CKD) mice models. Mechanistically, TET2 binds to and suppresses the activity of the P2 promoter within the RUNX2 gene, whereas an enzymatic loss-of-function mutation of TET2 has a comparable effect. Furthermore, TET2 forms a complex with histone deacetylases 1/2 (HDAC1/2 ) to deacetylate H3K27ac on the P2 promoter, thereby inhibiting its transcription. Moreover, SNIP1 is indispensable for TET2 to interact with HDAC1/2 to exert inhibitory effect on VC, and knockdown of SNIP1 accelerated VC in mice. Collectively, our findings imply that TET2 might serve as a potential therapeutic target for VC.
Authors
Dayu He, Jianshuai Ma, Ziting Zhou, Yanli Qi, Yaxin Lian, Feng Wang, Huiyong Yin, Huanji Zhang, Tingting Zhang, Hui Huang
Abstract
Elevated Angiopoietin-2 is associated with diverse inflammatory conditions including sepsis, a leading global cause of mortality. During inflammation, Angiopoietin-2 antagonizes the endothelium-enriched receptor Tie2 to destabilize the vasculature. In other contexts, Angiopoietin-2 stimulates Tie2. The basis for context-dependent antagonism remains incompletely understood. Here we show that inflammation-induced proteolytic cleavage of Angiopoietin-2 converts this ligand from Tie2 agonist to antagonist. Conditioned media from stimulated macrophages induced endothelial Angiopoietin-2 secretion. Unexpectedly, this was associated with reduction of the 75 kDa full-length protein and appearance of new 25 and 50 kDa C-terminal fragments. Peptide sequencing proposed cathepsin K as a candidate protease. Cathepsin K was necessary and sufficient to cleave Angiopoietin-2. Recombinant 25 and 50 kDa Angiopoietin-2 fragments (cANGPT225, cANGPT250) bound and antagonized Tie2. Cathepsin K inhibition with the Phase-3 small molecule inhibitor odanacatib improved survival in distinct murine sepsis models. Full-length Angiopoietin-2 enhanced survival in endotoxemic mice administered odanacatib and, conversely, increased mortality in the drug’s absence. Odanacatib’s benefit was reversed by heterologous cANGPT225. Septic humans accumulated circulating Angiopoietin-2 fragments, which were associated with adverse outcomes. These results identify cathepsin K as a candidate marker of sepsis and a proteolytic mechanism for the conversion of Angiopoietin-2 from Tie2 agonist to antagonist with therapeutic implications for inflammatory conditions associated with Angiopoietin-2 induction.
Authors
Takashi Suzuki, Erik Loyde, Sara Chen, Valerie Etzrodt, Temitayo O. Idowu, Amanda J. Clark, Marie Christelle Saade, Brenda Mendoza Flores, Shulin Lu, Gabriel Birrane, Vamsidhara Vemireddy, Benjamin Seeliger, Sascha David, Samir M. Parikh
An endothelial SOX18-mevalonate pathway axis enables repurposing of statins for infantile hemangioma
Abstract
Infantile hemangioma (IH) is the most common tumor in children and a paradigm for pathological vasculogenesis, angiogenesis, and regression. Propranolol, the mainstay treatment, inhibits IH vessel formation via a β-adrenergic receptor independent off-target effect of its R(+) enantiomer on the endothelial SRY box transcription factor 18 (SOX18). Transcriptomic profiling of patient-derived hemangioma stem cells (HemSC) uncovered the mevalonate pathway (MVP) as a target of R(+) propranolol. Loss and gain of function of SOX18 confirmed it is both necessary and sufficient for R(+) propranolol suppression of the MVP, including regulation of sterol regulatory element binding protein 2 (SREBP2) and the rate-limiting enzyme HMG-CoA reductase (HMGCR). AThe biological relevance of the endothelial SOX18-MVP axis in IH patient tissue was demonstrated by nuclear co-localization of SOX18 and SREBP2. Functional validation in a preclinical IH xenograft model revealed that statins – competitive inhibitors of HMGCR – efficiently suppress IH vessel formation. We propose an novel endothelial SOX18-MVP-axis as a central regulator of IH pathogenesis and suggest statin repurposing to treat IH. The pleiotropic effects of R(+) propranolol and statins along the SOX18-MVP axis to disable an endothelial-specific program may have therapeutic implications for other vascular disease entities involving pathological vasculogenesis and angiogenesis.
Authors
Annegret Holm, Matthew S. Graus, Jill Wylie-Sears, Jerry Wei Heng Tan, Maya Alvarez-Harmon, Luke Borgelt, Sana Nasim, Long Chung, Ashish Jain, Mingwei Sun, Liang Sun, Pascal Brouillard, Ramrada Lekwuttikarn, Yanfei Qi, Joyce Teng, Miikka Vikkula, Harry Kozakewich, John B. Mulliken, Mathias Francois, Joyce Bischoff
Abstract
Polymorphisms in Nos3 increases risk for glaucoma, the leading cause of irreversible blindness worldwide. A key modifiable risk factor for glaucoma is intraocular pressure (IOP), which is regulated by nitric oxide (NO), a product of nitric oxide synthase-3 (Nos3) in Schlemm’s canal of the conventional outflow pathway. We studied the effects of a conditional, endothelial-specific postnatal deletion of Nos3 (Endo-SclCre-ERT;Nos3flox/flox) on tissues of the outflow pathway. We observed that Cre-ERT expression spontaneously and gradually increased with time in vascular endothelia including Schlemm’s canal, beginning at P10, with complete Nos3 deletion occurring around P90. Unlike the reduced outflow resistance in global Nos3 knockout mice, outflow resistance and IOP in Endo-SclCre-ERT;Nos3flox/flox mice were normal. Coinciding with Nos3 deletion, we observed recruitment of macrophages to, and induction of both ELAM-1 and NOS2 expression by endothelia in the distal portion of the outflow pathway, which increased vessel diameter. These adjustments reduced outflow resistance to maintain IOP in these Endo-SclCre-ERT;Nos3flox/flox mice. Selective inhibition of iNOS by 1400W resulted in narrowing of distal vessels and IOP elevation. Together, results emphasize the pliability of the outflow system, the importance of NO signaling in IOP control and implicates an important role for macrophages in IOP homeostasis.
Authors
Ruth A. Kelly, Megan S. Kuhn, Ester Reina-Torres, Revathi Balasubramanian, Kristin M. Perkumas, Guorong Li, Takamune Takahashi, Simon W.M. John, Michael H. Elliott, Darryl R. Overby, W. Daniel Stamer
Copyright © 2025 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)