Immunoproteasomal Processing of IsoLG-Adducted Proteins Is Essential for Hypertension

BACKGROUND

Hypertension is characterized by CD8+ (cluster differentiation 8) T cell activation and infiltration into peripheral tissues. CD8+ T cell activation requires proteasomal processing of antigenic proteins. It has become clear that isoLG (isolevuglandin)-adduced peptides are antigenic in hypertension; however, IsoLGs inhibit the constitutive proteasome. We hypothesized that immunoproteasomal processing of isoLG-adducts is essential for CD8+ T cell activation and inflammation in hypertension.

METHODS

IsoLG adduct processing was studied in murine dendritic cells (DCs), endothelial cells (ECs), and B8 fibroblasts. The role of the proteasome and the immunoproteasome in Ang II (angiotensin II)-induced hypertension was studied in C57BL/6 mice treated with bortezomib or the immunoproteasome inhibitor PR-957 and by studying mice lacking 3 critical immunoproteasome subunits (triple knockout mouse). We also examined hypertension in mice lacking the critical immunoproteasome subunit LMP7 (large multifunctional peptidase 7) specifically in either DCs or ECs.

RESULTS

We found that oxidant stress increases the presence of isoLG adducts within MHC-I (class I major histocompatibility complex), and immunoproteasome overexpression augments this. Pharmacological or genetic inhibition of the immunoproteasome attenuated hypertension and tissue inflammation. Conditional deletion of LMP7 in either DCs or ECs attenuated hypertension and vascular inflammation. Finally, we defined the role of the innate immune receptors STING (stimulator of interferon genes) and TLR7/8 (toll-like receptor 7/8) as drivers of LMP7 expression in ECs.

CONCLUSIONS

These studies define a previously unknown role of the immunoproteasome in DCs and ECs in CD8+ T cell activation. The immunoproteasome in DCs and ECs is critical for isoLG-adduct presentation to CD8+ T cells, and in the endothelium, this guides homing and infiltration of T cells to specific tissues.

Immune mechanisms in the pathophysiology of hypertension

Hypertension is a leading risk factor for morbidity and mortality worldwide. Despite current anti-hypertensive therapies, most individuals with hypertension fail to achieve adequate blood pressure control. Moreover, even with adequate control, a residual risk of cardiovascular events and associated organ damage remains. These findings suggest that current treatment modalities are not addressing a key element of the underlying pathology. Emerging evidence implicates immune cells as key mediators in the development and progression of hypertension. In this Review, we discuss our current understanding of the diverse roles of innate and adaptive immune cells in hypertension, highlighting key findings from human and rodent studies. We explore mechanisms by which these immune cells promote hypertensive pathophysiology, shedding light on their multifaceted involvement. In addition, we highlight advances in our understanding of autoimmunity, HIV and immune checkpoints that provide valuable insight into mechanisms of chronic and dysregulated inflammation in hypertension.

Rac1 promotes kidney collecting duct repair by mechanically coupling cell morphology to mitotic entry

Prolonged obstruction of the ureter, which leads to injury of the kidney collecting ducts, results in permanent structural damage, while early reversal allows for repair. Cell structure is defined by the actin cytoskeleton, which is dynamically organized by small Rho guanosine triphosphatases (GTPases). In this study, we identified the Rho GTPase, Rac1, as a driver of postobstructive kidney collecting duct repair. After the relief of ureteric obstruction, Rac1 promoted actin cytoskeletal reconstitution, which was required to maintain normal mitotic morphology allowing for successful cell division. Mechanistically, Rac1 restricted excessive actomyosin activity that stabilized the negative mitotic entry kinase Wee1. This mechanism ensured mechanical G2-M checkpoint stability and prevented premature mitotic entry. The repair defects following injury could be rescued by direct myosin inhibition. Thus, Rac1-dependent control of the actin cytoskeleton integrates with the cell cycle to mediate kidney tubular repair by preventing dysmorphic cells from entering cell division.

High tissue-sodium associates with systemic inflammation and insulin resistance in obese individuals

BACKGROUND AND AIMS

High sodium intake is associated with obesity and insulin resistance, and high extracellular sodium content may induce systemic inflammation, leading to cardiovascular disease. In this study, we aim to investigate whether high tissue sodium accumulation relates with obesity-related insulin resistance and whether the pro-inflammatory effects of excess tissue sodium accumulation may contribute to such association.

METHODS AND RESULTS

In a cross-sectional study of 30 obese and 53 non-obese subjects, we measured insulin sensitivity determined as glucose disposal rate (GDR) using hyperinsulinemic euglycemic clamp, and tissue sodium content using ²³Na magnetic resonance imaging. Median age was 48 years, 68% were female and 41% were African American. Median (interquartile range) BMI was 33 (31.5, 36.3) and 25 (23.5, 27.2) kg/m² in the obese and non-obese individuals, respectively. In obese individuals, insulin sensitivity negatively correlated with muscle (r = -0.45, p = 0.01) and skin sodium (r = -0.46, p = 0.01). In interaction analysis among obese individuals, tissue sodium had a greater effect on insulin sensitivity at higher levels of high-sensitivity C-reactive protein (p-interaction = 0.03 and 0.01 for muscle and skin Na+, respectively) and interleukin-6 (p-interaction = 0.024 and 0.003 for muscle and skin Na+, respectively). In interaction analysis of the entire cohort, the association between muscle sodium and insulin sensitivity was stronger with increasing levels of serum leptin (p-interaction = 0.01).

CONCLUSIONS

Higher muscle and skin sodium are associated with insulin resistance in obese patients. Whether high tissue sodium accumulation has a mechanistic role in the development of obesity-related insulin resistance through systemic inflammation and leptin dysregulation remains to be examined in future studies.

CLINICALTRIALS

gov registration: NCT02236520.

Distinct CD3 + CD14 + T Cell-Monocytes are dynamic complexes that harbor HIV and are increased with glucose intolerance

Persistent systemic inflammation in persons with HIV (PWH) is accompanied by an increased risk of metabolic disease. Yet, changes in the innate and adaptive immune system in PWH who develop metabolic disease remain poorly defined. Using unbiased approaches, we show that PWH with prediabetes/diabetes have a significantly higher proportion of circulating CD14 + monocytes complexed to T cells. The complexed CD3 + T cells and CD14 + monocytes demonstrate functional immune synapses, increased expression of proinflammatory cytokines, and greater glucose utilization. Furthermore, these complexes harbor more latent HIV DNA compared to CD14 + monocytes or CD4 + T cells. Our results demonstrate that circulating CD3 + CD14 + T cell-monocyte pairs represent functional dynamic cellular interactions that likely contribute to inflammation and, in light of their increased proportion, may have a role in metabolic disease pathogenesis. These findings provide an incentive for future studies to investigate T cell-monocyte immune complexes as mechanistic in HIV cure and diseases of aging.

Highlights

Persons with HIV and diabetes have increased circulating CD3 + CD14 + T cell-monocyte complexes. CD3 + CD14 + T cell-monocytes are a heterogenous group of functional and dynamic complexes. We can detect HIV in T cell-monocyte complexes. The proportion of CD3 + CD14 + T cell-monocyte complexes is positively associated with blood glucose levels and negatively with plasma IL-10 and CD4 + T regulatory cells.

Immunoproteasomal Processing of Isolevuglandin Adducts in Hypertension

Isolevuglandins (isoLGs) are lipid aldehydes that form in the presence of reactive oxygen species (ROS) and drive immune activation. We found that isoLG-adducts are presented within the context of major histocompatibility complexes (MHC-I) by an immunoproteasome dependent mechanism. Pharmacologic inhibition of LMP7, the chymotrypsin subunit of the immunoproteasome, attenuates hypertension and tissue inflammation in the angiotensin II (Ang II) model of hypertension. Genetic loss of function of all immunoproteasome subunits or conditional deletion of LMP7 in dendritic cell (DCs) or endothelial cells (ECs) attenuated hypertension, reduced aortic T cell infiltration, and reduced isoLG-adduct MHC-I interaction. Furthermore, isoLG adducts structurally resemble double-stranded DNA and contribute to the activation of STING in ECs. These studies define a critical role of the immunoproteasome in the processing and presentation of isoLG-adducts. Moreover they define a role of LMP7 as a regulator of T cell activation and tissue infiltration in hypertension.

CD4+ T cells expressing CX3CR1, GPR56, with variable CD57 are associated with cardiometabolic diseases in persons with HIV

Persons with HIV (PWH) on long-term antiretroviral therapy (ART) have a higher incidence and prevalence of cardiometabolic diseases attributed, in part, to persistent inflammation despite viral suppression. In addition to traditional risk factors, immune responses to co-infections such as cytomegalovirus (CMV) may play an unappreciated role in cardiometabolic comorbidities and offer new potential therapeutic targets in a subgroup of individuals. We assessed the relationship of CX3CR1+, GPR56+, and CD57+/- T cells (termed CGC+) with comorbid conditions in a cohort of 134 PWH co-infected with CMV on long-term ART. We found that PWH with cardiometabolic diseases (non-alcoholic fatty liver disease, calcified coronary arteries, or diabetes) had higher circulating CGC+CD4+ T cells compared to metabolically healthy PWH. The traditional risk factor most correlated with CGC+CD4+ T cell frequency was fasting blood glucose, as well as starch/sucrose metabolites. While unstimulated CGC+CD4+ T cells, like other memory T cells, depend on oxidative phosphorylation for energy, they exhibited higher expression of carnitine palmitoyl transferase 1A compared to other CD4+ T cell subsets, suggesting a potentially greater capacity for fatty acid β-oxidation. Lastly, we show that CMV-specific T cells against multiple viral epitopes are predominantly CGC+. Together, this study suggests that among PWH, CGC+ CD4+ T cells are frequently CMV-specific and are associated with diabetes, coronary arterial calcium, and non-alcoholic fatty liver disease. Future studies should assess whether anti-CMV therapies could reduce cardiometabolic disease risk in some individuals.

Rosetta FlexPepDock to predict peptide-MHC binding: An approach for non-canonical amino acids

Computation methods that predict the binding of peptides to MHC-I are important tools for screening and identifying immunogenic antigens and have the potential to accelerate vaccine and drug development. However, most available tools are sequence-based and optimized only for peptides containing the twenty canonical amino acids. This omits a large number of peptides containing non-canonical amino acids (NCAA), or residues that undergo varied post-translational modifications such as glycosylation or phosphorylation. These modifications fundamentally alter peptide immunogenicity. Similarly, existing structure-based methods are biased towards canonical peptide backbone structures, which may or may not be preserved when NCAAs are present. Rosetta FlexPepDock ab-initio is a structure-based computational protocol able to evaluate peptide-receptor interaction where no prior information of the peptide backbone is known. We benchmarked FlexPepDock ab-initio for docking canonical peptides to MHC-I, and illustrate for the first time the method's ability to accurately model MHC-I bound epitopes containing NCAAs. FlexPepDock ab-initio protocol was able to recapitulate near-native structures (≤1.5Å) in the top lowest-energy models for 20 out of 25 cases in our initial benchmark. Using known experimental binding affinities of twenty peptides derived from an influenza-derived peptide, we showed that FlexPepDock protocol is able to predict relative binding affinity as Rosetta energies correlate well with experimental values (r = 0.59, p = 0.006). ROC analysis revealed 80% true positive and a 40% false positive rate, with a prediction power of 93%. Finally, we demonstrate the protocol's ability to accurately recapitulate HLA-A*02:01 bound phosphopeptide backbone structures and relative binding affinity changes, the theoretical structure of the lymphocytic choriomeningitis derived glycosylated peptide GP392 bound to MHC-I H-2Db, and isolevuglandin-adducted peptides. The ability to use non-canonical amino acids in the Rosetta FlexPepDock protocol may provide useful insight into critical amino acid positions where the post-translational modification modulates immunologic responses.

Mean Coronary Cross-Sectional Area as a Measure of Arterial Remodeling Using Noncontrast CT Imaging in Persons With HIV

Background Persons with HIV have a higher prevalence of coronary artery disease compared with their HIV-negative counterparts. Earlier identification of subclinical atherosclerosis may provide a greater opportunity for cardiovascular disease risk reduction. We investigated coronary cross-sectional area (CorCSA) by noncontrasted computed tomography imaging as a noninvasive measure of arterial remodeling among virally suppressed persons with HIV. Methods and Results We assessed 105 persons with HIV with a spectrum of cardiometabolic health. All participants underwent computed tomography imaging to assess the mean corCSA of the proximal left anterior descending artery and 28 participants underwent additional coronary computed tomography angiography. Partial Spearman rank correlations adjusted for cardiovascular disease risk factors were used to assess relationships of corCSA with anthropometric measurements, HIV-related factors, and plasma cytokines. Mean corCSA measured by noncontrast computed tomography and coronary computed tomography angiography were strongly correlated (ρ=0.91, P<0.0001). Higher mean corCSA was present in those with coronary artery calcium (P=0.005) and it correlated with participants' atherosclerotic cardiovascular disease risk score (ρ=0.35, P=0.01). After adjusting for established cardiovascular disease risk factors, we observed an inverse relationship between corCSA and CD4+ T-cell count (ρ=-0.2, P=0.047). Removal of age from the model strengthened the relationships between corCSA and antiretroviral therapy duration (from ρ=0.19, P=0.08 to ρ=0.3, P=0.01). CorCSA was also inversely correlated with plasma IL-10 (ρ=-0.25, P=0.03) but had no relationship with IL-6 (ρ=0.11, P=0.4) or IL-1β (ρ=0.08, P=0.5). Conclusions Positive coronary arterial remodeling, an imaging marker of subclinical atherosclerosis, is associated with a lower CD4 T-cell count, lower circulating IL-10, and possibly a longer antiretroviral therapy duration in persons with HIV. Registration Clinicaltrials.gov; Unique identifier: NCT04451980.

Role of Axl in target organ inflammation and damage due to hypertensive aortic remodeling

We have shown that excessive endothelial cell stretch causes release of growth arrest-specific 6 (GAS6), which activates the tyrosine kinase receptor Axl on monocytes and promotes immune activation and inflammation. We hypothesized that GAS6/Axl blockade would reduce renal and vascular inflammation and lessen renal dysfunction in the setting of chronic aortic remodeling. We characterized a model of aortic remodeling in mice following a 2-wk infusion of angiotensin II (ANG II). These mice had chronically increased pulse wave velocity, and their aortas demonstrated increased mural collagen. Mechanical testing revealed a marked loss of Windkessel function that persisted for 6 mo following ANG II infusion. Renal function studies showed a reduced ability to excrete a volume load, a progressive increase in albuminuria, and tubular damage as estimated by periodic acid Schiff staining. Treatment with the Axl inhibitor R428 beginning 2 mo after ANG II infusion had a minimal effect on aortic remodeling 2 mo later but reduced the infiltration of T cells, γ/δ T cells, and macrophages into the aorta and kidney and improved renal excretory capacity, reduced albuminuria, and reduced evidence of renal tubular damage. In humans, circulating Axl+/Siglec6+ dendritic cells and phospho-Axl+ cells correlated with pulse wave velocity and aortic compliance measured by transesophageal echo, confirming chronic activation of the GAS6/Axl pathway. We conclude that brief episodes of hypertension induce chronic aortic remodeling, which is associated with persistent low-grade inflammation of the aorta and kidneys and evidence of renal dysfunction. These events are mediated at least in part by GAS6/Axl signaling and are improved with Axl blockade.NEW & NOTEWORTHY In this study, a brief, 2-wk period of hypertension in mice led to progressive aortic remodeling, an increase in pulse wave velocity, and evidence of renal injury, dysfunction, and albuminuria. This end-organ damage was associated with persistent renal and aortic infiltration of CD8+ and γ/δ T cells. We show that this inflammatory response is likely due to GAS6/Axl signaling and can be ameliorated by blocking this pathway. We propose that the altered microvascular mechanical forces caused by increased pulse wave velocity enhance GAS6 release from the endothelium, which in turn activates Axl on myeloid cells, promoting the end-organ damage associated with aortic stiffening.

Abstract 132: Reduction Of Bone Quality In A Murine Model Of Essential Hypertension Relative To Age

Autoimmune and inflammatory diseases such as obesity and cancer are highly linked to altered bone growth and osteoporosis. Hypertension (HTN) is an inflammatory condition associated with reduced bone mineral density and increased risk for fragility fractures in adults. As cases of pediatric HTN rise in the United States, HTN may increase bone loss in children and future risk for osteoporosis. We hypothesized that HTN-induced osteoporosis in young mice reduces bone quality like that of aging. To assess this, 3.5- or 16-month-old male C57BL/6J mice received Angiotensin (Ang) II (490 ng/kg/day) or vehicle infusion by subcutaneous osmotic mini-pumps. After 6-weeks of infusion, the lumbar vertebral bodies (VB) were harvested, and analyzed by high-resolution micro-computed tomography and finite element analysis. In young mice, Ang-II induced HTN caused reductions in bone volume fraction (33.4 ± 0.8 vs 25.4 ± 1.1 %, p<0.0001) and trabecular thickness (66.4 ± 1.1 vs 54.3 ± 1.5 μm, p<0.0001). HTN reduced the estimated failure force (24.3 ± 0.7 vs 16.1 ± 1.1 N, p<0.0001) in young mice. In contrast to young mice, in aged mice Ang-II infusion did not induce bone loss; however, at baseline, the old mice exhibited reduced bone quality like that of hypertensive young mice: bone volume fraction (22.5 ± 0.7 vs 25.4 ± 1.1 %, p=0.2928), trabecular thickness (58.0 ± 1.5 vs 54.3 ± 1.1 μm, p=0.3866), and estimated failure force (17.6 ± 0.8 vs 16.1 ± 1.1 N, p=0.6517). To ascertain the impact of inflammation in the bone marrow microenvironment, the bone marrow was analyzed by flow cytometry. The number of CD4 + T cells producing IL-17A was increased in hypertensive vs normotensive young mice (230.0 ± 8.9 vs 167.3 ± 16.6 cells per 1 million events, p=0.0035), as were dendritic cells (408.3 ± 29.1 vs. 229.1 ± 20.5 cells per 1 million events, p<0.0001). CD4 + T cells producing IFN-γ also rose (2845 ± 129 vs 2437 ± 174 cells per 1 million events, p=0.07) in young hypertensive mice. Both normotensive and hypertensive old mice experienced overactive inflammatory responses compared to the young group. Thus, HTN mimics aspects of aging on bone health, causing inflammation in the bone marrow and osteoporosis. Efforts to detect and treat HTN in children may deter untoward events related to bone loss in adulthood.

Abstract P236: Role Of Axl In Target Organ Inflammation And Damage Due To Hypertensive Aortic Remodeling

Background: Aortic remodeling enhances arterial pulsatility in the microcirculation and we have shown that excessive endothelial stretch increases release of Growth Arrest Specific 6 (GAS6), which activates Axl on monocytes causing immune activation and inflammation.

Hypothesis: GAS6/Axl blockade reduces renal and vascular inflammation and lessens renal dysfunction caused by aortic remodeling.

Methods and Results: Three month old male C57Bl/6 mice received osmotic minipumps containing vehicle or ang II for 2 weeks and the pumps removed. Aortas demonstrated increased collagen and an 80% loss of Windkessel function that persisted for 6 months following ang II. Renal function studies showed reduced ability to excrete a volume load, a progressive increase in albuminuria and tubular damage as estimated by Periodic Acid Schiff staining. Treatment with the Axl inhibitor R428 beginning 2 months after ang II had minimal effect on aortic remodeling 2 months later, but reduced aortic and renal infiltration of T cells, gamma/delta T cells and macrophages as measured by flow cytometry (Figure). R428 also improved renal excretory capacity, decreased urinary NGAL, reduced albuminuria, and attenuated renal tubular damage. Interestingly, macrophage/T cell complexes were present in aortas of mice previously exposed to hypertension, and were reduced by R428.

Conclusion: Brief episodes of hypertension induce chronic aortic remodeling which increases Axl signaling and transformation of monocytes to inflammatory antigen presenting cells that activate T cells. Axl blockade might serve as a therapeutic option to improve end-organ damage after an episode of hypertension.

Abstract 019: T Cell Recognition Of Isolevuglandin-adducted Proteins In Hypertension Is Mhc Class 1-restricted

Introduction: Isolevuglandins (isoLGs) are peroxidized lipids that covalently bond lysine residues to modify self-antigens in hypertension. We hypothesized that isoLG-adduction restricts peptide presentation to specific class 1 major histocompatibility complexes (MHC) in mice and humans.

Methods and Results: We developed 2 mouse strains expressing either his-tagged class 1 MHC-I H-2D b or H-2K b with truncated membrane binding domains. Shed MHC-I from cultured splenoctyes was adsorbed onto nickel-agarose beads and used to stimulate T cells. We found that CD8+ T cell proliferation is restricted to H-2D b and not H-2K b (Fig 1A) and occurs only if both T-cells and soluble H-2D b are from hypertensive (angiotensin II-treated) mice. Proliferation was blocked if donors received an isoLG-scavenger or by an isoLG specific antibody added during the proliferation assay (Fig 1B). Fluorescence resonance energy transfer (FRET) demonstrated that isoLG-adducts associate with MHC-1 H-2D b and not H-2K b . We transfected HLA-null K562 cells with 18 common human HLA subtypes, and induced isoLG formation with tert-butyl hydroperoxide. Using FRET we identified human HLAs that are high, intermediate and low presenters of isoLG adducts (Fig 1C). Unique modeling software identified candidate peptides and showed that structural characteristics of H-2D b cause lysines at positions 4-7 to project from the MHC groove and present isoLGs (Fig 1D-E).

Conclusion: IsoLG adduct presentation is MHC-1 restricted. This may explain differences in the degree of inflammation and end-organ damage observed between populations with hypertension and provides a possible new approach to personalized care.

Abstract 130: Isolevuglandins Drive Neutrophil Migration In Hypertension And Are Essential For The Formation Of Neutrophil Extracellular Traps

Introduction: Neutrophil extracellular traps (NETs) consist of decondensed chromatin and proteins including citrullinated histone 3, myeloperoxidase, and neutrophil elastase . Previous studies describe a role of neutrophils and NETs in hypertension and associated end-organ damage. Isolevuglandins (IsoLGs) are products of lipid peroxidation that play a role in immune activation in hypertension. We hypothesized that isoLGs are necessary for the process of NETosis and neutrophil migration in hypertension.

Methods: C57BL/6 mice were treated with 490 ng/kg/min angiotensin (Ang) II and vehicle or the isoLG scavenger, 2-hydroxybenzylamine (2HOBA). Single cell sequencing was performed on spleens. NETs were quantified by flow cytometry and immunofluorescence. Human neutrophils were isolated and treated with ionomycin and vehicle or ethyl-2HOBA (Et2HOBA). Neutrophil chromatin expansion was determined by live cell confocal microscopy.

Results: Single cell sequencing revealed increased splenic neutrophil accumulation following Ang II treatment. This was attenuated with 2HOBA co-treatment (Ang II 7.78%, Ang II + 2HOBA 2.46%, n=3). Flow cytometry revealed a marked increase in aortic NET accumulation that was reduced with 2HOBA (Sham 304 ± 110.6, Ang II 3,522 ± 928.6, Ang II + 2HOBA 1,007 ± 340.9 NETs, n=6-7). Immunofluorescence staining of kidneys revealed an increase in NET area in Ang II treated mice and a reduction with 2HOBA co-treatment (Sham 75.64 ± 27.2, Ang II 636.9 ± 105.0, Ang II + 2HOBA 14.98 ± 7.5 μm 2 , n=4-6). Ionomycin induced NETosis of isolated human neutrophils was associated with isoLG adduct accumulation that was attenuated with Et2HOBA co-treatment (54.24 ± 11.77% vs 1.78 ± 0.41%, n=5). Live cell confocal microscopy revealed NET area was increased 9.2-fold with ionomycin treatment compared to control. Pretreatment with Et2HOBA attenuated this response. Finally, isoLGs directly disrupt nucleosome assembly in vitro .

Conclusion: These findings demonstrate an essential role of isoLGs in NETosis and neutrophil migration in hypertension. Moreover, they suggest a role of isoLG scavengers in the treatment of hypertension and additional NET-associated diseases including atherosclerosis and lupus.

IsoLGs (Isolevuglandins) Drive Neutrophil Migration in Hypertension and Are Essential for the Formation of Neutrophil Extracellular Traps

BACKGROUND

IsoLGs (isolevuglandins) are electrophilic products of lipid peroxidation formed in the presence of reactive oxygen species. IsoLGs contribute to hypertension by an unknown mechanism. Studies have shown that reactive oxygen species production drives the formation of neutrophil extracellular traps (NETs) and that NETs accumulate within the aorta and kidneys of patients with hypertension. The purpose of this study was to determine the role of isoLGs in neutrophil migration and NET formation (NETosis) in hypertension.

METHODS

Mice were treated with Ang II (angiotensin II) and the specific isoLG scavenger 2-hydroxybenzylamine and examined for tissue neutrophil and NET accumulation by single-cell sequencing and flow cytometry. Isolated human neutrophils were studied to determine the role of isoLGs in NETosis and neutrophil chromatin expansion by immunofluorescence and live cell confocal microscopy.

RESULTS

Single-cell sequencing performed on sham, Ang II, and Ang II+2-hydroxybenzylamine treated mice revealed neutrophils as a primary target of 2-hydroxybenzylamine. Peripheral neutrophil migration, aortic NET accumulation, and renal NET accumulation is blocked with 2-hydroxybenzylamine treatment. In isolated human neutrophils, isoLGs accumulate during NETosis and scavenging of isoLGs prevents NETosis. IsoLGs drive neutrophil chromatin expansion during NETosis and disrupt nucleosome structure.

CONCLUSIONS

These observations identified a critical role of isoLGs in neutrophil migration and NETosis in hypertension and provide a potential therapy for NET-associated diseases including hypertension and associated end organ damage.

Isolevuglandins disrupt PU.1-mediated C1q expression and promote autoimmunity and hypertension in systemic lupus erythematosus

We describe a mechanism responsible for systemic lupus erythematosus (SLE). In humans with SLE and in 2 SLE murine models, there was marked enrichment of isolevuglandin-adducted proteins (isoLG adducts) in monocytes and dendritic cells. We found that antibodies formed against isoLG adducts in both SLE-prone mice and humans with SLE. In addition, isoLG ligation of the transcription factor PU.1 at a critical DNA binding site markedly reduced transcription of all C1q subunits. Treatment of SLE-prone mice with the specific isoLG scavenger 2-hydroxybenzylamine (2-HOBA) ameliorated parameters of autoimmunity, including plasma cell expansion, circulating IgG levels, and anti-dsDNA antibody titers. 2-HOBA also lowered blood pressure, attenuated renal injury, and reduced inflammatory gene expression uniquely in C1q-expressing dendritic cells. Thus, isoLG adducts play an essential role in the genesis and maintenance of systemic autoimmunity and hypertension in SLE.

Interleukin-17A is associated with flow-mediated dilation and interleukin-4 with carotid plaque in persons with HIV

OBJECTIVE

Chronic inflammation contributes to the high burden of cardiovascular disease (CVD) in persons with HIV (PWH). HIV has broad effects on innate and adaptive immune cells, including innate lymphoid cells (ILCs) and CD4+ T-helper cells. At present, the relationship between CVD and plasma cytokines reflecting ILC/T-helper responses in PWH is not well defined. We investigated relationships between plasma cytokines and subclinical atherosclerosis.

DESIGN

A cross-sectional study.

METHODS

We recruited 70 PWH on a single antiretroviral regimen (efavirenz, teno- fovir, and emtricitabine) with at least 12 months of suppressed viremia and 30 HIVnegative controls. We quantified plasma cytokines and chemokines, including inter- feron-g, interleukin (IL)-4, IL-13, and IL-17A, markers of macrophage activation, and markers of endothelial activation using multiplex assays and ELISA. Cytokines were grouped using Ward's hierarchical clustering. Brachial artery flow-mediated dilation (FMD) and carotid plaque burden were determined using ultrasound. Multivariable linear regression and negative binomial regression analyses were used to assess the relationships of plasma biomarkers and endpoints adjusted for CVD risk factors.

RESULTS

We identified three distinct clusters in PWH, one containing Th1/Th2/ILC1/ ILC2 type cytokines, one with Th17/ILC3/macrophage-related cytokines, and a less specific third cluster. Lower FMD was associated with higher plasma IL-17A and macrophage inflammatory protein-1 a. In contrast, IL-4, a Th2/ILC2 type cytokine, was associated with carotid plaque. When HIV-negative controls were added to the models clustering was more diffuse, and these associations were attenuated or absent.

CONCLUSION

Th17/ILC3 and Th2/ILC2-mediated immune mechanisms may have distinct roles in endothelial dysfunction and atherosclerotic plaque formation, respectively, in PWH.

Breast cancer chemotherapy induces vascular dysfunction and hypertension through NOX4 dependent mechanism

Cardiovascular disease is the major cause of morbidity and mortality in breast cancer survivors. Chemotherapy contributes to this risk. We aimed to define the mechanisms of long-term vascular dysfunction caused by neoadjuvant chemotherapy (NACT) and identify novel therapeutic targets.We studied arteries from postmenopausal women who had undergone breast cancer treatment using docetaxel, doxorubicin and cyclophosphamide (NACT), and women with no history of such treatment matched for key clinical parameters. Mechanisms were explored in wild-type and Nox4-/- mice and human microvascular endothelial cells.Endothelium-dependent vasodilatation is severely impaired in patients after NACT, while endothelium-independent responses remain normal. This was mimicked by 24-hour exposure of arteries to NACT agents ex-vivo. When applied individually, only docetaxel impaired endothelial function in human vessels. Mechanistic studies showed that NACT increased inhibitory eNOS phosphorylation of threonine 495 in a ROCK-dependent manner and augmented vascular superoxide and hydrogen peroxide production and NADPH oxidase activity. Docetaxel increased expression of NADPH oxidase NOX4 in endothelial and smooth muscle cells and NOX2 in the endothelium. NOX4 increase in human arteries may be mediated epigenetically by diminished DNA methylation of the NOX4 promoter. Docetaxel induced endothelial dysfunction and hypertension in mice. These were prevented in Nox4-/- and by pharmacological inhibition of Nox4 or Rock.Commonly used chemotherapeutic agents, and in particular, docetaxel, alter vascular function by promoting inhibitory phosphorylation of eNOS and enhancing ROS production by NADPH oxidases.

Tissue Sodium in Patients With Early Stage Hypertension: A Randomized Controlled Trial

Background

Sodium (Na⁺) stored in skin and muscle tissue is associated with essential hypertension. Sodium magnetic resonance imaging is a validated method of quantifying tissue stores of Na⁺. In this study, we evaluated tissue Na⁺ in patients with elevated blood pressure or stage I hypertension in response to diuretic therapy or low Na⁺ diet.

Methods and Results

In a double‐blinded, placebo‐controlled trial, patients with systolic blood pressure 120 to 139 mm Hg were randomized to low sodium diet (<2 g of sodium), chlorthalidone, spironolactone, or placebo for 8 weeks. Muscle and skin Na⁺ using sodium magnetic resonance imaging and pulse wave velocity were assessed at the beginning and end of the study. Ninety‐eight patients were enrolled to undergo baseline measurements and 54 completed randomization. Median baseline muscle and skin Na⁺ in 98 patients were 16.4 mmol/L (14.9, 18.9) and 13.1 mmol/L (11.1, 16.1), respectively. After 8 weeks, muscle Na⁺ increased in the diet and chlorthalidone arms compared with placebo. Skin sodium was decreased only in the diet arm compared with placebo. These associations remained significant after adjustment for age, sex, body mass index, systolic blood pressure, and urinary sodium. No changes were observed in pulse wave velocity among the different groups when compared with placebo.

Conclusions

Diuretic therapy for 8 weeks did not decrease muscle or skin sodium or improve pulse wave velocity in patients with elevated blood pressure or stage I hypertension.

Registration

URL: https://www.clinicaltrials.gov; Unique identifier: NCT02236520.

A Message to the Hypertension Community Regarding the Ukraine Crisis

As the world comes to terms with the devastating impact of the COVID-19 pandemic that has contributed to enormous health, economic and social challenges worldwide, we find ourselves with the reality of a new challenge - Russia's war in Ukraine. This war has led to an enormous upheaval of human life and has forced millions of people to leave their home for safety in other countries as refugees. The Editors of Hypertension wish to express their extreme sorrow and empathy for the citizens of this war-torn area. We are particularly concerned for our fellow physicians, scientists, academics, post-doctoral fellows and students in Ukraine and find attacks on hospitals, health care facilities and academic institutions to be deplorable. [Download the PDF to view the full Editorial].

Growth Arrest Specific-6 and Axl Coordinate Inflammation and Hypertension

[Figure: see text].

Therapeutic targeting of inflammation in hypertension: from novel mechanisms to translational perspective

Both animal models and human observational and genetic studies have shown that immune and inflammatory mechanisms play a key role in hypertension and its complications. We review the effects of immunomodulatory interventions on blood pressure, target organ damage, and cardiovascular risk in humans. In experimental and small clinical studies, both non-specific immunomodulatory approaches, such as mycophenolate mofetil and methotrexate, and medications targeting T and B lymphocytes, such as tacrolimus, cyclosporine, everolimus, and rituximab, lower blood pressure and reduce organ damage. Mechanistically targeted immune interventions include isolevuglandin scavengers to prevent neo-antigen formation, co-stimulation blockade (abatacept, belatacept), and anti-cytokine therapies (e.g. secukinumab, tocilizumab, canakinumab, TNF-α inhibitors). In many studies, trial designs have been complicated by a lack of blood pressure-related endpoints, inclusion of largely normotensive study populations, polypharmacy, and established comorbidities. Among a wide range of interventions reviewed, TNF-α inhibitors have provided the most robust evidence of blood pressure lowering. Treatment of periodontitis also appears to deliver non-pharmacological anti-hypertensive effects. Evidence of immunomodulatory drugs influencing hypertension-mediated organ damage are also discussed. The reviewed animal models, observational studies, and trial data in humans, support the therapeutic potential of immune-targeted therapies in blood pressure lowering and in hypertension-mediated organ damage. Targeted studies are now needed to address their effects on blood pressure in hypertensive individuals.

Abstract 04: Growth Arrest Specific 6 And Axl Signaling Coordinate Endothelial Cell And Immune Cell Activation To Promote Inflammation And Hypertension

Endothelial cells (ECs) activated by hypertensive (10%) cyclical stretch releases factors including IL-6 and hydrogen peroxide that stimulate the conversion of human monocytes to an intermediate inflammatory phenotype. A novel subset of DCs in humans has been identified that express Axl and Sigelc-6 + (AS DCs) which drive T cells proliferation and produce inflammatory cytokines. The interplay between ECs and AS DCs in hypertension is unkown. We assessed AS DCs by flow cytometry in normotensive (n=23) and hypertensive (n=11) subjects and found a significant increase in AS DCs in hypertensive compared to normotensive subjects (297 ± 73 vs. 108 ± 26/ml; p =0.0304). When moncoytes were exposed to human aortic endothelial cells (HAECs) undergoing 10% stretch, the formation of AS DCs was markedly enhanced compared to 5%. The ligand for Axl is growth arrest specific 6 (GAS6), and we found that 10% HAEC stretch caused a 50% increase in the release of GAS6 by ECs comapred to 5%. We knocked down either EC GAS6 or Axl using siRNA and either of these abrogated the ability of ECs to promote AS DC formation. Using flow cytometry to analyze venous ECs that had been harvested from 23 volunteers to quantify EC activation and GAS6 secretion in vivo, we found a positive association between GAS6 and ICAM-1 (R 2 =0.39, p =0.0012). We found a positive association between pulse pressure and plasma GAS6 (R 2 =0.25, p =0.0079) ands systolic blood pressure and GAS6 (R 2 =0.19, p=0.0025) in volunteers. We found that plasma GAS6 is increased in Ang II hypertension and that either genetic deletion or pharmacological inhibition of Axl lowered blood pressure in reposne to Ang II and reduced renal inflammation. To investigate the role of immunological vs. stromal Axl in vivo, we perfomed bone marrow transplant studies and found that both Axl WT/WT ->Axl -/- and Axl -/- ->Axl W/WT had a significant reduction in blood pressure by 20 mmHg compared to the Axl WT/WT -> Axl WT/WT control. These data show that both immunological and stromal Axl contribute to hypertension and inflammation and GAS6/Axl signlaing may be a novel therapeutic target in this disease.

Abstract P214: Isolevuglandins Mediate Inflammatory Gene Expression And Immune Activation In Hypertension And Systemic Lupus Erythematosus

Justification: Hypertension and systemic lupus erythematosus (SLE) share similarities including elevations of blood pressure, proteinuria, inflammation and renal dysfunction and both involve formation of isoLG adducts. We hypothesized that isoLG scavenging would modulate overlapping gene pathways in inflammatory cells in these two conditions.

Methods: We performed 10 X genomics single cell sequencing on splenocytes of C57Bl/6 mice with angiotensin II (Ang II)-induced hypertension, Ang II co-treatment with the isoLG scavenger 2HOBA, and 24-week-old B6.SLE123 mice with or without 6-weeks of 2HOBA. Matched C57Bl/6 females were used as controls for the B6.SLE123 mice.

Results: Both models exhibited myeloid expansion and genes associated with neutrophil infiltration compared to their respective controls and 2HOBA attenuated this ( Table 1 ). Hypertension was associated with neutrophil expansion whereas SLE was associated an expansion of neutrophils, monocytes, and dendritic cells. In SLE, 2HOBA predominantly modulated gene expression in dendritic cells. Gene ontology revealed 2HOBA downregulated genes governing inflammation including Il1 β (Avglog2(fold change) = -1.6, P adj = 0.002) in both hypertension and SLE.

Conclusions: In a mouse model of SLE, scavenging of isoLGs with 2HOBA downregulates inflammatory genes specifically in DCs. In models of both hypertension and SLE, scavenging of isoLG prevents neutrophil expansion. Combined these data describe a shared role of isoLGs in hypertension and SLE and suggest a specific role of DCs and neutrophil activation in the pathogenesis of both conditions. Table 1. Percentage of myeloid derived cells in all groups.

Abstract MP53: A Role Of Anti-isolevuglandin-adduct Antibody Production In Hypertension

Isolevuglandins (isoLG) are products of lipid oxidation that covalently ligate self-proteins and contribute to immune activation in hypertension. We hypothesized that these are recognized as “non-self” elicit an antibody response. To determine the presence of anti-isoLG adduct antibodies in humans, immunoblots were performed using endogenous antibodies present in plasma of healthy and hypertensive subjects against human proteins artificially adducted with isoLG. Protein-G HRP was used to visualize the binding of IgG antibodies. We found that humans with hypertension possess IgG antibodies that bind isoLG protein adducts to a greater extent compared to unadducted protein. To identify unique monoclonal antibodies to isoLG adducts C57Bl/6 mice were made hypertensive via angiotensin II infusion for two weeks and then boosted with kidney protein that was adducted with isoLG. Boosted mice were then sacrificed and splenic B-cells were fused with a myeloma cell line. Individual colonies were screened for reactivity with isoLG adducts identifying 11 monoclonal antibody clones with a high specificity for isoLG adducts. Four clones were chosen for further analysis that exhibited 1.5 to 6-fold affinity to adducted vs unadducted mouse proteins. Western blots of normotensive and hypertensive kidney, bone marrow, and heart protein lysate using one of our monoclonal antibodies (clone 2B11) revealed a 90 kDa protein that is increased in bone marrow of hypertensive mice. We conclude that hypertension results in the production of anti-isoLG adduct antibodies in mice and humans. Identification of unique monoclonal antibodies that react with isoLG adducts suggests clonal expansion of anti-isoLG antibody producing cells. Finally, a hypertensive antigen is recognized by the 2B11 clone. Future studies will utilize these antibodies to identify peptide antigens that drive immune activation in hypertension.

Abstract MP01: Deacetylation Of Mitochondrial Cyclophilin D K166 Inhibits Cytokine-induced Oxidative Stress And Attenuates Hypertension

We have previously reported that depletion Cyclophilin D (CypD), a regulatory subunit of mitochondrial permeability transition pore, improves vascular function and attenuates hypertension, however, specific regulation of CypD in hypertension is not clear. Analysis of human arterioles from hypertensive patients did not reveal alterations in CypD levels but showed 3-fold increase in CypD acetylation. We hypothesized that CypD-K166 acetylation promotes vascular oxidative stress and hypertension, and measures to reduce CypD acetylation can improve vascular function and reduce hypertension. Essential hypertension and animal models of hypertension are linked to inactivation of mitochondrial deacetylase Sirt3 by highly reactive lipid oxidation products, isolevuglandins (isoLGs), and supplementation of mice with mitochondria targeted scavenger of isoLGs, mito2HOBA, improves CypD deacetylation. To test the specific role of CypD-K166 acetylation, we developed CypD-K166R deacetylation mimic mutant mice. Mitochondrial respiration, vascular function and systolic blood pressure in CypD-K166R mice was similar to wild-type C57Bl/6J mice. Meanwhile, angiotensin II-induced hypertension was substantially attenuated in CypD-K166R mice (144 mmHg) compared with wild-type mice (161 mmHg). Angiotensin II infusion in wild-type mice significantly increased mitochondrial superoxide, impaired endothelial dependent relaxation, and reduced the level of endothelial nitric oxide which was prevented in angiotensin II-infused CypD-K166R mice. Hypertension is linked to increased levels of inflammatory cytokines TNFα and IL-17A promoting vascular oxidative stress and end-organ damage. We have tested if CypD-K166R mice are protected from cytokine-induced oxidative stress. Indeed, ex vivo incubation of aorta with the mixture of angiotensin II, TNFα and IL-17A (24 hours) increased mitochondrial superoxide by 2-fold in wild-type aortas which was abrogated in CypD-K166R mice. These data support the pathophysiological role of CypD acetylation in inflammation, oxidative stress and hypertensive end-organ damage. We propose that targeting CypD acetylation may have therapeutic potential in treatment of vascular dysfunction and hypertension.

Abstract 53: Results Of The Nashville Barber-pharmacist Hypertension Management Pilot Study

Background: The Los Angeles Barbershop Blood Pressure Study (LABBPS) demonstrated that collaboration between barbers and pharmacists delivering hypertension management could significantly improve blood pressure as well as access to care. It is unknown if this model can be translated to other locations. This single-arm, proof-of-concept pilot study tested the development and implementation of a similar protocol in Nashville, TN (NCT04232124).

Methods: Between 2019 and 2021, community stakeholders, clinicians, investigators, and the LABBPS team convened to adapt the study design and protocol. Established barbershops with barbers willing to be trained on study procedures were recruited as study sites. Non-Hispanic Black male clients, aged 35-79 years with systolic blood pressure (SBP) > 140 mmHg on two screening days were eligible for participation. Enrolled participants met with a pharmacist for lifestyle and medication management at least once monthly for a six-month period. Barbers measured blood pressure during haircuts for additional monitoring.

Results: Eight barbershops in business for an average of 20 (± 5) years participated in the trial. Barbers from each shop (range: 1-4) were trained. A total of 419 clients completed screening visit 1, 82 were eligible and 52 (12%) completed visit 2. We enrolled 36, with 30 completing the initial clinical visit and 27 had complete data at 6-months. Participants were on average age 50 (± 10) years, had a body mass index 33 (± 6), 44% were currently smoking, 52% with high school or less education, and 56% reported current primary care. Baseline BP 157.7±17.1/ 95.1±13.9 mmHg improved to 125.7±11.9/75.6±9.5, a change of -32.1±21.6/ -19.5±14.1, respectively. At 6-months 85% of the group had a BP<140/90, 74% BP<135/85, and 67% BP<130/80. At baseline 15% of participants reported health as excellent/very good and this increased to 56% at 6-months (p=0.002). Adverse reactions reported were minimal.

Conclusion: Implementation of the barber-pharmacist model of hypertension management and care delivery improved BP control among hypertensive Black men in Nashville. Lessons learned regarding adaptation overcoming unforeseen barriers will inform expansion into additional naïve locations for future research.

Sodium activates human monocytes via the NADPH oxidase and isolevuglandin formation

AIMS

Prior studies have focused on the role of the kidney and vasculature in salt-induced modulation of blood pressure; however, recent data indicate that sodium accumulates in tissues and can activate immune cells. We sought to examine mechanisms by which salt causes activation of human monocytes both in vivo and in vitro.

METHODS AND RESULTS

To study the effect of salt in human monocytes, monocytes were isolated from volunteers to perform several in vitro experiments. Exposure of human monocytes to elevated Na+ex vivo caused a co-ordinated response involving isolevuglandin (IsoLG)-adduct formation, acquisition of a dendritic cell (DC)-like morphology, expression of activation markers CD83 and CD16, and increased production of pro-inflammatory cytokines tumour necrosis factor-α, interleukin (IL)-6, and IL-1β. High salt also caused a marked change in monocyte gene expression as detected by RNA sequencing and enhanced monocyte migration to the chemokine CC motif chemokine ligand 5. NADPH-oxidase inhibition attenuated monocyte activation and IsoLG-adduct formation. The increase in IsoLG-adducts correlated with risk factors including body mass index, pulse pressure. Monocytes exposed to high salt stimulated IL-17A production from autologous CD4+ and CD8+ T cells. In addition, to evaluate the effect of salt in vivo, monocytes and T cells isolated from humans were adoptively transferred to immunodeficient NSG mice. Salt feeding of humanized mice caused monocyte-dependent activation of human T cells reflected by proliferation and accumulation of T cells in the bone marrow. Moreover, we performed a cross-sectional study in 70 prehypertensive subjects. Blood was collected for flow cytometric analysis and 23Na magnetic resonance imaging was performed for tissue sodium measurements. Monocytes from humans with high skin Na+ exhibited increased IsoLG-adduct accumulation and CD83 expression.

CONCLUSION

Human monocytes exhibit co-ordinated increases in parameters of activation, conversion to a DC-like phenotype and ability to activate T cells upon both in vitro and in vivo sodium exposure. The ability of monocytes to be activated by sodium is related to in vivo cardiovascular disease risk factors. We therefore propose that in addition to the kidney and vasculature, immune cells like monocytes convey salt-induced cardiovascular risk in humans.

Pathophysiology of Hypertension: The Mosaic Theory and Beyond

Dr Irvine Page proposed the Mosaic Theory of Hypertension in the 1940s advocating that hypertension is the result of many factors that interact to raise blood pressure and cause end-organ damage. Over the years, Dr Page modified his paradigm, and new concepts regarding oxidative stress, inflammation, genetics, sodium homeostasis, and the microbiome have arisen that allow further refinements of the Mosaic Theory. A constant feature of this approach to understanding hypertension is that the various nodes are interdependent and that these almost certainly vary between experimental models and between individuals with hypertension. This review discusses these new concepts and provides an introduction to other reviews in this compendium of Circulation Research.

Anticytomegalovirus CD4+ T Cells Are Associated With Subclinical Atherosclerosis in Persons With HIV

[Figure: see text].

Isolevuglandin-Modified Cardiac Proteins Drive CD4+ T-Cell Activation in the Heart and Promote Cardiac Dysfunction

BACKGROUND

Despite the well-established association between T-cell-mediated inflammation and nonischemic heart failure, the specific mechanisms triggering T-cell activation during the progression of heart failure and the antigens involved are poorly understood. We hypothesized that myocardial oxidative stress induces the formation of isolevuglandin (IsoLG)-modified proteins that function as cardiac neoantigens to elicit CD4+ T-cell receptor (TCR) activation and promote heart failure.

METHODS

We used transverse aortic constriction in mice to trigger myocardial oxidative stress and T-cell infiltration. We profiled the TCR repertoire by mRNA sequencing of intramyocardial activated CD4+ T cells in Nur77^GFP reporter mice, which transiently express GFP on TCR engagement. We assessed the role of antigen presentation and TCR specificity in the development of cardiac dysfunction using antigen presentation-deficient MhcII^-/- mice and TCR transgenic OTII mice that lack specificity for endogenous antigens. We detected IsoLG protein adducts in failing human hearts. We also evaluated the role of reactive oxygen species and IsoLGs in eliciting T-cell immune responses in vivo by treating mice with the antioxidant TEMPOL and the IsoLG scavenger 2-hydroxybenzylamine during transverse aortic constriction, and ex vivo in mechanistic studies of CD4+ T-cell proliferation in response to IsoLG-modified cardiac proteins.

RESULTS

We discovered that TCR antigen recognition increases in the left ventricle as cardiac dysfunction progresses and identified a limited repertoire of activated CD4+ T-cell clonotypes in the left ventricle. Antigen presentation of endogenous antigens was required to develop cardiac dysfunction because MhcII^-/- mice reconstituted with CD4+ T cells and OTII mice immunized with their cognate antigen were protected from transverse aortic constriction-induced cardiac dysfunction despite the presence of left ventricle-infiltrated CD4+ T cells. Scavenging IsoLGs with 2-hydroxybenzylamine reduced TCR activation and prevented cardiac dysfunction. Mechanistically, cardiac pressure overload resulted in reactive oxygen species-dependent dendritic cell accumulation of IsoLG protein adducts, which induced robust CD4+ T-cell proliferation.

CONCLUSIONS

Our study demonstrates an important role of reactive oxygen species-induced formation of IsoLG-modified cardiac neoantigens that lead to TCR-dependent CD4+ T-cell activation within the heart.

Endothelial function in cardiovascular medicine: a consensus paper of the European Society of Cardiology Working Groups on Atherosclerosis and Vascular Biology, Aorta and Peripheral Vascular Diseases, Coronary Pathophysiology and Microcirculation, and Thrombosis

Endothelial cells (ECs) are sentinels of cardiovascular health. Their function is reduced by the presence of cardiovascular risk factors, and is regained once pathological stimuli are removed. In this European Society for Cardiology Position Paper, we describe endothelial dysfunction as a spectrum of phenotypic states and advocate further studies to determine the role of EC subtypes in cardiovascular disease. We conclude that there is no single ideal method for measurement of endothelial function. Techniques to measure coronary epicardial and micro-vascular function are well established but they are invasive, time-consuming, and expensive. Flow-mediated dilatation (FMD) of the brachial arteries provides a non-invasive alternative but is technically challenging and requires extensive training and standardization. We, therefore, propose that a consensus methodology for FMD is universally adopted to minimize technical variation between studies, and that reference FMD values are established for different populations of healthy individuals and patient groups. Newer techniques to measure endothelial function that are relatively easy to perform, such as finger plethysmography and the retinal flicker test, have the potential for increased clinical use provided a consensus is achieved on the measurement protocol used. We recommend further clinical studies to establish reference values for these techniques and to assess their ability to improve cardiovascular risk stratification. We advocate future studies to determine whether integration of endothelial function measurements with patient-specific epigenetic data and other biomarkers can enhance the stratification of patients for differential diagnosis, disease progression, and responses to therapy.

Tissue sodium stores in peritoneal dialysis and hemodialysis patients determined by 23-sodium magnetic resonance imaging

BACKGROUND

Tissue sodium content in patients on maintenance hemodialysis (MHD) and peritoneal dialysis (PD) were previously explored using 23Sodium magnetic resonance imaging (23NaMRI). Larger studies would provide a better understanding of sodium stores in patients on dialysis as well as the factors influencing this sodium accumulation.

METHODS

In this cross-sectional study, we quantified the calf muscle and skin sodium content in 162 subjects (10 PD, 33 MHD patients, and 119 controls) using 23NaMRI. Plasma levels of interleukin-6 (IL-6) and high-sensitivity C-reactive protein (hsCRP) were measured to assess systemic inflammation. Sixty-four subjects had repeat 23NaMRI scans that were analyzed to assess the repeatability of the 23NaMRI measurements.

RESULTS

Patients on MHD and PD exhibited significantly higher muscle and skin sodium accumulation compared to controls. African American patients on dialysis exhibited greater muscle and skin sodium content compared to non-African Americans. Multivariable analysis showed that older age was associated with both higher muscle and skin sodium. Male sex was also associated with increased skin sodium deposition. Greater ultrafiltration was associated with lower skin sodium in patients on PD (Spearman's rho=-0.68, P = 0.035). Higher plasma IL-6 and hsCRP levels correlated with increased muscle and skin sodium content in the overall study population. Patients with higher baseline tissue sodium content exhibited greater variability in tissue sodium stores on repeat measurements.

CONCLUSIONS

Our findings highlight greater muscle and skin sodium content in dialysis patients compared to controls without kidney disease. Tissue sodium deposition and systemic inflammation seen in dialysis patients might influence one another bidirectionally.

Mitochondrial Isolevuglandins Contribute to Vascular Oxidative Stress and Mitochondria-Targeted Scavenger of Isolevuglandins Reduces Mitochondrial Dysfunction and Hypertension

Hypertension remains a major health problem in Western Societies, and blood pressure is poorly controlled in a third of patients despite use of multiple drugs. Mitochondrial dysfunction contributes to hypertension, and mitochondria-targeted agents can potentially improve treatment of hypertension. We have proposed that mitochondrial oxidative stress produces reactive dicarbonyl lipid peroxidation products, isolevuglandins, and that scavenging of mitochondrial isolevuglandins improves vascular function and reduces hypertension. To test this hypothesis, we have studied the accumulation of mitochondrial isolevuglandins-protein adducts in patients with essential hypertension and Ang II (angiotensin II) model of hypertension using mass spectrometry and Western blot analysis. The therapeutic potential of targeting mitochondrial isolevuglandins was tested by the novel mitochondria-targeted isolevuglandin scavenger, mito2HOBA. Mitochondrial isolevuglandins in arterioles from hypertensive patients were 250% greater than in arterioles from normotensive subjects, and ex vivo mito2HOBA treatment of arterioles from hypertensive subjects increased deacetylation of a key mitochondrial antioxidant, SOD2 (superoxide dismutase 2). In human aortic endothelial cells stimulated with Ang II plus TNF (tumor necrosis factor)-α, mito2HOBA reduced mitochondrial superoxide and cardiolipin oxidation, a specific marker of mitochondrial oxidative stress. In Ang II-infused mice, mito2HOBA diminished mitochondrial isolevuglandins-protein adducts, raised Sirt3 (sirtuin 3) mitochondrial deacetylase activity, reduced vascular superoxide, increased endothelial nitric oxide, improved endothelium-dependent relaxation, and attenuated hypertension. Mito2HOBA preserved mitochondrial respiration, protected ATP production, and reduced mitochondrial permeability pore opening in Ang II-infused mice. These data support the role of mitochondrial isolevuglandins in endothelial dysfunction and hypertension. We conclude that scavenging of mitochondrial isolevuglandins may have therapeutic potential in treatment of vascular dysfunction and hypertension.

Abstract MP41: A Role Of Isolevuglandins In Systemic Lupus Erythematosus Associated Autoimmunity And Hypertension

Essential hypertension and systemic lupus erythematosus (SLE) are devastating conditions that disproportionately affect women. SLE has heterogeneous manifestations and treatment is limited to the use of non-specific global immunosuppression. Importantly, there is an increased prevalence of hypertension in women with SLE compared to healthy controls. Isolevuglandins (IsoLGs) are oxidation products of fatty acids that form as a result of reactive oxygen species. These molecules adduct covalently to lysine residues of proteins. Adducted proteins are then presented as autoantigens to T-cells resulting in immune cell activation. Previous studies have shown an essential role of IsoLGs in immune cell activation and the development of hypertension in animal models. We hypothesize that isoLGs are important for the development of hypertension and systemic immune activation in SLE. We first examined isoLG adduct accumulation within monocytes of human subjects with SLE compared to healthy controls. By flow cytometry, we found marked accumulation of isoLG adducts within CD14 + monocytes (34.2% ± 12.4% vs 3.81% ± 2.1% of CD14 + , N = 10-11, P <0.05). We confirmed this increase in isoLG adducts by mass spectrometry. To determine a causative role of isoLG adducts in immune activation and hypertension in SLE, we employed the B6.SLE123 and NZBWF1 mouse models of SLE. Animals were treated with the isoLG scavenger 2-hydroxybenzylamine (2-HOBA) or vehicle beginning at 7 weeks and were sacrificed at 32 weeks of age. C57BL/6 and NZW were used as controls. Importantly, treatment with 2-HOBA attenuated blood pressure in both mouse models (systolic BP 136.2 ± 5.6 mmHg for B6.SLE123 vs 120.9 ± 4.46 mmHg for B6.SLE123 +2HOBA; 164.7 ± 24.4 mmHg for NZBWF1 vs 136.9 ± 14.9 mmHg for NZBWF1 +2HOBA, N = 6-8, P < 0.05). Moreover, treatment with 2-HOBA reduced albuminuria and renal injury in the B6.SLE123 model (albumin/creatinine ratio 33.8 ± 2.0 x 10 -2 μg/mg for B6.SLE123 vs 5.5 ± 0.9 x 10 -2 μg/mg for B6.SLE123 +2HOBA, N = 7-9, P < 0.05). Finally, immune cell accumulation in primary and secondary lymphoid organs is significantly attenuated by 2-HOBA. These studies suggest a critical role of isoLG adduct accumulation in both systemic immune activation and hypertension in SLE.

Abstract P140: Myeloid Activation in Hypertension and Effects on Bone: A New End Organ?

Hypertension affects approximately one-half of the adult population. Another common disease is osteoporosis, which affects 53 million people in the United States. Clinical studies have shown an association between hypertension and bone loss. We hypothesized that experimental hypertension would be associated with osteoporosis. In Angiotensin (Ang) II-induced hypertension, there is an increase in hematopoietic stem cells (HSCs) expressing the master myeloid transcription factor PU.1 (2.99 ± 0.92) vs. sham (0.17 ± 0.04,p=0.007). Here we reported an increase an osteoclasts number per mm 2 by Tartrate-resistant acid phosphatase staining in DOCA-salt hypertension (27.4 ± 2.3) vs. sham (12.09 ± 1.7, p=0.0002). Using microCT analysis of femoral bone, we found that Ang II-induced hypertension caused striking bone loss as reflected by decreases in cortical bone area, cortical thickness and trabecular number (see Table). We also examined bone strength using a three-point biomechanical testing. In keeping with the micro-CT data, both forms of hypertension were associated with increased bone fragility, reflected by several parameters including maximum force to failure and rigidity (see Table). Recent studies have implicated T cells in the genesis of osteoporosis, and in keeping with this, we found almost two-fold increase in both CD4 + and CD8 + T cells in the marrow of mice with DOCA-salt hypertension. Thus, in two models of experimental hypertension there is marked bone loss and the development of bone fragility, potentially related to T cell accumulation and cytokine release. These findings might explain the association between osteoporosis and hypertension.

Abstract P074: Mitochondrial Isolevuglandins Contribute To Vascular Oxidative Stress And Mitochondria-targeted Scavenger Of Isolevuglandins Reduces Mitochondrial Dysfunction And Hypertension

Hypertension remains a major health problem in Western Societies, and blood pressure is poorly controlled in a third of patients despite use of multiple drugs. Mitochondrial dysfunction contributes to hypertension and mitochondria-targeted agents can potentially improve treatment of hypertension. We have proposed that mitochondrial oxidative stress produces reactive dicarbonyl lipid peroxidation products isolevuglandins (isoLGs) and that scavenging of mitochondrial isoLG improves vascular function and reduces hypertension. To test this hypothesis, we have studied the accumulation of mitochondrial isoLG-protein adducts in human patients with essential hypertension and angiotensin II mouse model of hypertension using mass spectrometry and Western blot analysis. The therapeutic potential of targeting mitochondrial isoLG was tested by the novel mitochondria-targeted isoLG scavenger, mito2HOBA. Mitochondrial isoLG in arterioles isolated from hypertensive patients were 250% greater than in arterioles from normotensive subjects, and ex vivo mito2HOBA treatment of arterioles from hypertensive subjects improved deacetylation of a key mitochondrial antioxidant, superoxide dismutase 2 (SOD2). In human aortic endothelial cells, mito2HOBA diminished mitochondrial superoxide and inhibited cardiolipin oxidation, a specific marker of mitochondrial oxidative stress. In angiotensin II-infused mice, mito2HOBA prevented accumulation of mitochondrial isoLG-protein adducts, improved Sirt3 mitochondrial deacetylase activity, reduced vascular superoxide, increased endothelial nitric oxide, improved endothelium-dependent relaxation, and attenuated hypertension. Mito2HOBA preserved mitochondrial respiration, protected ATP production, and reduced mitochondrial permeability pore opening in angiotensin II-infused mice. These data support the role of mitochondrial isoLGs in endothelial dysfunction and hypertension. We conclude that scavenging of mitochondrial isoLGs may have therapeutic potential in treatment of vascular dysfunction and hypertension.

Abstract MP27: Human Hypertension And Endothelial Cell Activation Promote The Formation And Activation Of Axl + Siglec-6 + Dendritic Cells Via Endothelial Release Of Growth Arrest Specific 6

We have shown that dendritic cells (DCs) from hypertensive mice convey hypertension when adoptively transferred to recipients. Recently a novel subset of DCs in humans that express Axl and Sigelc-6 + (AS DCs) have been identified which drive T cell proliferation and produce IL-1β, IL-6 and IL-23, consistent with DCs we have observed in hypertension. We hypothesized that AS cells are increased in hypertension and contribute to immune activation in this disease. We quantified circulating AS DCs by flow cytometry in normotensive (n=23) and hypertensive (n=11) subjects and found a more than 2-fold increase in circulating AS DCs in hypertensive compared to normotensive subjects (297 ± 73 vs. 108 ± 26/ml; p =0.0304). To investigate the mechanism by which AS DCs are formed in hypertension, we co-cultured human aortic endothelial cells (HAECs) undergoing either normotensive (5%) or hypertensive (10%) cyclical stretch for 48 hours with CD14 + monocytes from normotensive donors. Co-culture of monocytes with HAECs exposed to 10% stretch significantly increased AS DCs and AS DC IL-1β production when compared to 5% stretch alone as assessed by flow cytometry (21 ± 5 vs. 131 ± 32 IL-1β + AS DCs). Moreover, inhibition of Axl signaling with R248, completely abolished the production of IL-1β in AS DCs (34 ± 8 IL-1β + AS DCs). In additional experiments we found that 10% stretch caused a 50% increase in release of growth arrest 6 (GAS6), the ligand for Axl, from HAECs compared to 5% stretch. Treatment of human monocytes with GAS6 mimicked the effect of 10% stretch in promoting AS cell formation and IL-1β production. Based on the increased secretion of GAS6 from HAECs, we used a J-wire to harvest human endothelial cells from 23 additional volunteers to assess endothelial cell activation and GAS6 secretion in vivo. We found a positive association between pulse pressure and plasma GAS6 (R 2 =0.25, p =0.0079) and a striking positive association between GAS6 and ICAM-1 (R 2 =0.39, p =0.0012). These data show that secretion of GAS6 by an activated endothelial seems to promote the formation and activation of AS DCs. Thus, the interplay between endothelial-derived GAS6 and AS DCs seem to be an important mechanism in human hypertension and might be a novel therapeutic target for this disease.

Highly Reactive Isolevuglandins Promote Atrial Fibrillation Caused by Hypertension

Oxidative damage is implicated in atrial fibrillation (AF), but antioxidants are ineffective therapeutically. The authors tested the hypothesis that highly reactive lipid dicarbonyl metabolites, or isolevuglandins (IsoLGs), are principal drivers of AF during hypertension. In a hypertensive murine model and stretched atriomyocytes, the dicarbonyl scavenger 2-hydroxybenzylamine (2-HOBA) prevented IsoLG adducts and preamyloid oligomers (PAOs), and AF susceptibility, whereas the ineffective analog 4-hydroxybenzylamine (4-HOBA) had minimal effect. Natriuretic peptides generated cytotoxic oligomers, a process accelerated by IsoLGs, contributing to atrial PAO formation. These findings support the concept of pre-emptively scavenging reactive downstream oxidative stress mediators as a potential therapeutic approach to prevent AF.

Report of the National Heart, Lung, and Blood Institute Working Group on Hypertension: Barriers to Translation

The National Heart, Lung, and Blood Institute convened a multidisciplinary working group of hypertension researchers on December 6 to 7, 2018, in Bethesda, MD, to share current scientific knowledge in hypertension and to identify barriers to translation of basic into clinical science/trials and implementation of clinical science into clinical care of patients with hypertension. The goals of the working group were (1) to provide an overview of recent discoveries that may be ready for testing in preclinical and clinical studies; (2) to identify gaps in knowledge that impede translation; (3) to highlight the most promising scientific areas in which to pursue translation; (4) to identify key challenges and barriers for moving basic science discoveries into translation, clinical studies, and trials; and (5) to identify roadblocks for effective dissemination and implementation of basic and clinical science in real-world settings. The working group addressed issues that were responsive to many of the objectives of the National Heart, Lung, and Blood Institute Strategic Vision. The working group identified major barriers and opportunities for translating research to improved control of hypertension. This review summarizes the discussion and recommendations of the working group.