Vascular biology
Abstract
Subendothelial retention of cholesterol-rich apolipoprotein-B-containing lipoproteins drives atherosclerotic arterial disease. In peripheral interstitial fluid from patients with type 2 diabetes (T2D), levels of such particles have been shown to be paradoxically reduced relative to those in serum, presumably reflecting their increased retention within the arterial wall. To identify possible mechanisms involved in lipoprotein retention in T2D, we obtained serum and skin blister fluid from such patients and matched controls, together with skin biopsies in a subset of individuals. In T2D, smaller LDL and VLDL remnant particles were more prominent in serum, but not in interstitial fluid, reflecting their enhanced vascular entrapment. The interstitial-fluid-to-serum ratio of apolipoprotein-B was 58% lower in T2D than in controls (0.14 vs 0.33), concomitant with increased susceptibility for LDL binding to proteoglycans. The most marked differences were seen in patients with clinically evident cardiovascular disease. The degree of transvascular retention was positively related to the propensity of isolated serum LDL to bind aortic proteoglycans, both in T2D and in controls. Skin unesterified cholesterol levels were higher in T2D patients relative to healthy controls. With aging, both proteoglycan binding and apparent vascular retention of LDL increased in controls, but not in T2D, indicating that these mechanisms may also be relevant for atherogenesis in non-diabetic individuals.
Authors
Pär Björklund, Jennifer Härdfeldt, Lauri Äikäs, Sara Straniero, Minna Holopainen, Katariina Öörni, Mats J. Rudling, Bo Angelin
Abstract
Hypoxia critically restricts the effectiveness of immunotherapy in triple-negative breast cancer (TNBC). Comprehensive bioinformatics analyses demonstrated that highly hypoxic TNBC tumors exhibited elevated T cell exhaustion, increased immune checkpoint molecule expression, and diminished responsiveness to immune checkpoint blockade (ICB). Consequently, strategies aimed at alleviating tumor hypoxia may effectively augment ICB therapy. Although ultrasound-targeted microbubble cavitation (UTMC) has been shown to reduce tumor hypoxia, the precise molecular mechanisms remain unclear. Here, we provided evidence that UTMC activated endothelial nitric oxide synthase (eNOS) through G protein–coupled signaling, resembling pathways induced by fluid shear stress. UTMC-induced eNOS activation was largely Ca²⁺-dependent and resulted in increased nitric oxide production. Enhanced nitric oxide generation was associated with improved tumor perfusion and reduced hypoxia. Combining UTMC with anti–PD-L1 therapy markedly improved the tumor immune microenvironment, characterized by increased CD8+ T cell infiltration, reduced T cell exhaustion, diminished regulatory T cell infiltration, increased macrophage polarization from an M2 to M1 phenotype, and elevated production of pro-inflammatory cytokines. Collectively, our findings identified UTMC as a promising adjunctive therapeutic approach to mitigate hypoxia and enhance the efficacy of anti–PD-L1 immunotherapy in TNBC. These results support further translational evaluation of UTMC-based combination strategies in hypoxic TNBC.
Authors
Zhiyu Zhao, Li Ba, Siwei Li, Jianxin Wang, Yuzhou Luo, Sihan Wang, Yan Jin, Changjun Wu
Abstract
The RhoBTB1-Cullin3 (CUL3) pathway in smooth muscle cells (SMCs) controls the ubiquitination and proteasomal degradation of target proteins that regulate vasodilation, vasoconstriction, and the actin cytoskeleton, and through this blood pressure (BP) and arterial stiffness. Using proximity labelling coupled with mass spectrometry in A7R5 SMCs, we identified proteins which bound to the C-terminal half of RhoBTB1 which functions as an adapter to deliver substrates to CUL3. We examined the physiological relevance of one of these substrates, RbFox2. Co-immunoprecipitation validated the interaction of RbFox2 with RhoBTB1. RbFox2 expression was elevated in response to inhibition of the ubiquitination-proteasomal pathway, CUL3-deficiency, and RhoBTB1 inhibition by either siRNA or angiotensin II (ANG). RbFox2 was ubiquitinated in a RhoBTB1- and CUL3-dependent manner suggesting its regulation through the RhoBTB1-CUL3-dependent ubiquitin-proteasome pathway. Inhibition of RbFox2 impaired the actin cytoskeleton in A7R5 cells and in primary SMC from RbFox2Flox/Flox (RbFox2F/F) mice and decreased the levels of globular and filamentous actin. ANG increased BP and arterial stiffness of RbFox2F/F mice, but the progression of arterial stiffness was halted after SMC-specific RbFox2 deletion despite a continued rise in BP. We conclude that RhoBTB1 and RbFox2 are important regulators of arterial stiffness through a mechanism that influences cytoskeletal integrity.
Authors
Gaurav Kumar, Nisita Chaihongsa, Daniel T. Brozoski, Daria Golosova, Ibrahim Vazirabad, Ko-Ting Lu, Kelsey K. Wackman, Ravi K. Singh, Curt D. Sigmund
Abstract
β-arrestins are ubiquitously expressed cytosolic adaptor proteins that regulate G protein-coupled receptor-dependent and -independent pathways essential for numerous physiological functions. This study investigated the role of β-arrestin1 and -2 in embryonic lymphatic vessel development and survival by generating and characterizing mice with lymphatic, tamoxifen-inducible loss of the genes encoding β-arrestin-1 and -2 (Arrb1/2ΔiLEC). At embryonic day15.5 (E15.5), Arrb1/2ΔiLEC embryos exhibit profound hydrops fetalis and increased embryonic mortality compared to control Arrb1/2fl/fl embryos. Edematous Arrb1/2ΔiLEC embryos, which were more often represented by the female sex, showed growth restriction and decreased lymphatic endothelial cell (LEC) proliferation in the jugular lymphatic sac compared to controls. In vitro knockdown of β-arrestin1 in LECs increased proliferation and increased activation of AKT, while knockdown of β-arrestin2 decreased proliferation and decreased activation of both ERK and CREB. Arrb1/2ΔiLEC embryos also exhibited dilated dermal lymphatics with decreased continuous VE-Cadherin adherens junctions compared to controls. These results were recapitulated in vitro in β-arrestin1 and/or -2 knockdown human LECs, which showed a decrease in membrane VE-Cadherin and β-catenin levels, and prevention of adrenomedullin-induced linearization of VE-cadherin at endothelial cell–cell junctions. Collectively, these results demonstrate that loss of β-arrestin1/2 in lymphatics causes hydrops fetalis, mid-gestational growth arrest and embryonic demise associated with reduced LEC proliferation and disrupted VE-Cadherin adherens junctions.
Authors
Yanna Tian, D. Stephen Serafin, Monserrat Avila-Zozaya, Alyssa M. Tauro, Natalie M. Torres-Valle, Bryan M. Kistner, Danielle M. Dy, Elizabeth S. Douglas, Kathleen M. Caron
Abstract
Thoracic Aortic Aneurysm and Dissections (TAAD) is a progressive dilation of the aortic wall associated with degradation of the extracellular matrix (ECM), cystic medial degeneration, smooth muscle cell (SMC) dysfunction, and rarefaction. TAAD etiology and pathogenesis suggest that alteration of mechanical force propagation may contribute to SMC dysfunction. This study aims to determine the role of SMC focal adhesion proteins, which are key components of force transmission, in TAAD pathogenesis. scRNAseq analysis of human TAA aortas showed reduced expression of intracellular focal adhesion components, including PTK2 (FAK), VCL, ILK, and TES transcripts, in SMCs. Additionally, protein levels of FAK, ILK, and VCL were decreased in the aorta of patients with TAA. SMC-specific Ptk2, Vcl, and Ilk knockout mice treated with β-Aminopropionitrile (BAPN) exhibited increased mortality, aortic dilation, ECM breakdown, and SMC loss. Mechanistically, knocking down FAK, ILK, and VCL exacerbated gliotoxin-induced SMC anoikis, whereas overexpressing full-length wild-type (WT) and dead-kinase FAK conferred resistance to apoptosis and cell detachment, indicating that FAK's protective effects depend on its expression rather than its enzymatic activity. Inhibition of FAK kinase activity did not affect SMC apoptosis in vitro or aortic dilation in vivo. Our findings demonstrated that the expression of focal adhesion proteins protects against TAAD progression and SMC anoikis independently of FAK kinase activity.
Authors
Zhenyuan Zhu, Mingjun Liu, Jianxin Wei, Deepa Suryanarayan, Parya Behzadi, Robert Edgar, Julie A. Phillippi, Cynthia St. Hilaire, Cristina Espinosa-Diez, Delphine Gomez
Abstract
Glucagon-like peptide-1 (GLP-1) and glucose-induced insulinotropic polypeptide (GIP) receptor agonists have revolutionized obesity therapy but causes for obesity-associated dysregulation of endogenous incretin production remain incompletely understood. Here we show that intestinal transmembrane serine protease 2 (TMPRSS2) plays a pivotal role in deregulating anti-diabetic GLP-1 production in obesity. TMPRSS2 is widely co-expressed in intestinal epithelial cells (IEC) along with its signaling target protease activated receptor 2 (PAR2). In addition to its role in regulating coagulation protease-mediated adipose tissue inflammation, PAR2 signaling in the gut controls postprandial GIP secretion. TMPRSS2, but not the epithelial-expressed proteases FXa or matriptase, activates PAR2 and thereby promotes postprandial GIP release. Accordingly, a PAR2 mutant mouse resistant to TMPRSS2 cleavage is protected from GIP upregulation and diet induced obesity. In the context of obesity, TMPRSS2 also attenuates bioavailability of ghrelin pathway and thereby suppresses GLP-1-mediated control of glucose homeostasis. Pharmacological inhibition or genetic deletion of TMPRSS2 restores ghrelin signaling dependent GLP-1 secretion and GLP-1’s anti-diabetic effects on nutritional glucose homeostasis. Thus, epithelial cell-expressed TMPRSS2, which critically contributes to the lung pathology in SARS-CoV-2 infection, emerges as an intestinal incretin regulator and a potential link between infection and chronic cardiometabolic diseases.
Authors
Dilraj Kaur, Sagarika Chakrabarty, Claudius Witzler, Hongjie Wang, Mengwen Wang, Romina Wolz, Petra Wilgenbus, Jens J.N. Posma, P. Sivaramakrishna Rachakonda, Federico Marini, Valeriya V. Zinina, Sabine Reyda, Rajinikanth Gogiraju, Claudine Graf, Fahumiya Samad, Katrin Schäfer, Christoph Reinhardt, Natalia Soshnikova, Wolfram Ruf, Thati Madhusudhan
Abstract
Aberrant neutrophil (PMN) accumulation in the tissue induces chronic vascular diseases. Endothelial cells (ECs) regulate the access of PMNs into the tissue from the blood. However, the mechanisms that prevent PMNs from being activated and accumulating in the tissue, a hallmark of acute lung injury (ALI), remain elusive. We demonstrate that conditional deletion of Erg in ECs spontaneously alters the PMN transcriptome, which is enriched with genes that induce PMN recruitment, adhesion, activation, and 'do not eat me' signals due to impaired synthesis of the deubiquitinase, A20. Decreased A20 levels, in turn, activated the transcription factor NFκB and the secretion of MIP2α (human homolog of IL8) in ECs. EC-secreted MIP2α/IL8 engaged the CXCR2 cascade on PMNs, leading to their activation and inflammatory injury. These findings were recapitulated in the lungs and blood of PMNs from patients dying of ALI. Overexpression of the A20 gene in EC or pharmacological inhibition of CXCR2 on PMNs in iEC-Erg–/– mice rescued EC control of PMNs and tissue homeostasis, and enhanced mouse survival after pneumonia. Thus, the EC-Erg-A20 axis regulates PMN accumulation and hyperactivation in the lungs by inhibiting EC-mediated IL-8 activation of PMN-CXCR2, thereby providing a potential target for neutrophilic inflammatory vascular diseases.
Authors
Vigneshwaran Vellingiri, Vijay Avin Balaji Ragunathrao, Jagdish Chandra Joshi, Md Zahid Akhter, Mumtaz Anwar, Somenath Banerjee, Sayanti Datta, Viktor Pinneker, Steven M. Dudek, Yoshikazu Tsukasaki, Sandra Pinho, Dolly Mehta
Abstract
Patients with COVID-19 who develop platelet-activating antibodies represent a subset at heightened thrombotic risk, yet the immune features associated with this response remains to be defined. We applied single-cell RNA sequencing of B- and T-cells, single B-cell V(D)J sequencing, and plasma cytokine and chemokine analysis to define immune signatures distinguishing patients who did (PEA+) or did not (PEA–) develop these antibodies. PEA⁺ patients showed prominent transcriptional enrichment of inflammatory, antigen-presentation, and B-cell receptor signaling pathways within antigen-experienced B-cell subsets. Expanded B-cell clones in PEA+ patients were disproportionately enriched within atypical memory B-cells and exhibited upregulated IFN-γ–response signatures, increased proliferative mutational patterns, limited class switching, and a significant overrepresentation of RKH/Y5 heavy-chain motifs associated with platelet-activating antibodies, consistent with an extrafollicular-biased response. Parallel T-cell profiling revealed IL-12 pathway enrichment across most T-cell subsets, increased IFN-γ transcription, and elevated plasma levels of Th1-associated cytokines in PEA+ patients. Collectively, these data highlight a coordinated inflammatory environment marked by Th1-skewed T-cell activation and selective expansion of atypical memory B-cell clones carrying RKH/Y5 motifs, defining immunologic features associated with platelet-activating antibody development in COVID-19.
Authors
Nathan Witman, Mei Yu, Yuqi Zhang, Kexin Gai, Yuhong Chen, Lu Zhou, Christine Nguyen, Wen Zhu, Yongwei Zheng, Shawn M. Jobe, Mary Beth Graham, Weiguo Cui, Demin Wang, Renren Wen
Abstract
Angiopoietin-2 (ANGPT2) is known to destabilize vascular barriers in most peripheral organs; however, its role in the brain vasculature remains poorly understood. To investigate its physiological function within the brain vasculature, we analyzed constitutive Angpt2 knockout (KO) mice in adulthood. We showed that loss of ANGPT2 leads to region-specific vascular malformations and blood-brain barrier (BBB) dysfunction, resulting in differential permeability to 1 kDa and 70 kDa fluorescent tracers. Notably, overt vascular malformations appeared only in select brain regions that allowed leakage of both tracers. These malformations were characterized by dilated, intertwined, and sprouting endothelial cells, surrounded by reactive perivascular cells, along with high levels of astrocyte- and neuron-derived vascular endothelial growth factor A (VEGFA) and elevated expression of the vascular receptors VEGF receptor 2 (KDR) and neuropilin 1 (NRP1). Other cortical areas without obvious malformations exhibited significant leakage of the 1 kDa tracer. We also demonstrated that different cell types took up the tracers after passing the BBB. Our findings identified ANGPT2 as an important factor involved in the regulation of cerebrovascular architecture, barrier integrity, and endothelial–parenchymal interactions, and uncovered surprising differences in the leakage patterns and cellular uptake of two widely used BBB tracers.
Authors
Weihan Li, Elisa Vázquez-Liébanas, Chanaëlle Fébrissy, Florent Sauvé, Jianhao Wang, Doğan Emre Sayıner, Pia Buslaps, Amanda Norrén, Michael Vanlandewijck, Liqun He, Marie Jeansson, Lars Muhl, Maarja Andaloussi Mäe
Abstract
Oxidative signaling is a central mechanism in alcohol-induced injury and has a strong implication in blood-brain barrier (BBB) dysregulation and neuroinflammation. Here, by targeting oxidative signaling, we hypothesized an innovative approach to develop a clinically relevant therapeutic strategy for alleviating alcohol-mediated neurovascular damage. To accomplish this, we enhanced the endogenous activity of Nrf2 (nuclear factor E2-related factor 2) by treating with an Nrf2 activator III TAT peptide (Nrf2 peptide, NP) and investigated the neuroprotective role of Nrf2 in promoting antioxidant defense properties and reducing BBB damage and transmigration of leukocytes to the brain following alcohol ingestion. We administered the NP subcutaneously to alcohol-ingested mice and evaluated its therapeutic potential in alleviating alcohol-associated neurovascular impairments. We compared the results with control peptide (random sequence with TAT)-treated animals. The studies showed that the NP treatment preserved the oxidant-antioxidant balance, downregulated ICAM-1 and its receptors, and mitigated BBB damage and leukocyte infiltration into the brain. We validated the effect of the NP in Nrf2 knock-out (KO) mice (Nrf2−/−). Thus, this study demonstrates NP’s neurovascular protective effects by regulating the oxidant-antioxidant balance, reducing oxidative stress-induced BBB disruption, and limiting transmigration of immune cells to the brain in a mouse model of alcohol ingestion.
Authors
Bibhuti B. Saikia, Saleena Alikunju, Yemin A. Poovanthodi, Zayan Kassim, P. M. Abdul Muneer
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