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.

The presence of xanthine dehydrogenase is crucial for the maturation of the rat kidneys.

The development of the kidney involves essential cellular processes, such as cell proliferation and differentiation, which are led by interactions between multiple signaling pathways. Xanthine dehydrogenase (XDH) catalyzes the reaction producing uric acid in the purine catabolism, which plays a multifaceted role in cellular metabolism. Our previous study revealed that the genetic ablation of the Xdh gene in rats leads to smaller kidneys, kidney damage, decline of renal functions, and failure to thrive. Rats, unlike humans, continue their kidney development postnatally. Therefore, we explored whether XDH plays a critical role in kidney development using SS-/- rats during postnatal development phase. XDH expression was significantly increased from postnatal day 5 to 15 in wild-type but not homozygote rat kidneys. The transcriptomic profile of renal tissue revealed several dysregulated pathways due to the lack of Xdh expression with the remodeling in inflammasome, purinergic signaling, and redox homeostasis. Further analysis suggested that lack of Xdh affects kidney development, likely via dysregulation of epidermal growth factor and its downstream STAT3 signaling. The present study showed that Xdh is essential for kidney maturation. Our data, alongside the previous research, suggests that loss of Xdh function leads to developmental issues, rendering them vulnerable to kidney diseases in adulthood.

LNK/SH2B3 loss of function increases susceptibility to murine and human atrial fibrillation.

AIMS: The lymphocyte adaptor protein (LNK) is a negative regulator of cytokine and growth factor signaling. The rs3184504 variant in SH2B3 reduces LNK function and is linked to cardiovascular, inflammatory, and hematologic disorders including stroke. In mice, deletion of Lnk causes inflammation and oxidative stress. We hypothesized that Lnk-/- mice are susceptible to atrial fibrillation (AF) and that rs3184504 is associated with AF and AF-related stroke in humans. During inflammation, reactive lipid dicarbonyls are a major component of oxidative injury, and we further hypothesized that these mediators are critical drivers of the AF substrate in Lnk-/- mice. METHODS AND RESULTS: Lnk-/- or wild-type (WT) mice were treated with vehicle or 2-hydroxybenzylamine (2-HOBA), a dicarbonyl scavenger, for 3 months. Compared to WT, Lnk-/- mice displayed increased AF duration that was prevented by 2-HOBA. In the Lnk-/- atria, action potentials were prolonged with reduced transient outward K+ current, increased late Na+ current, and reduced peak Na+ current, proarrhythmic effects that were inhibited by 2-HOBA. Mitochondrial dysfunction, especially for complex I, was evident in Lnk-/- atria, while scavenging lipid dicarbonyls prevented this abnormality. Tumor necrosis factor-α (TNF-α) and interleukin-1ß (IL-1ß) were elevated in Lnk-/- plasma and atrial tissue, respectively, both of which caused electrical and bioenergetic remodeling in vitro. Inhibition of soluble TNF-α prevented electrical remodeling and AF susceptibility, while IL-1ß inhibition improved mitochondrial respiration but had no effect on AF susceptibility. In a large database of genotyped patients, rs3184504 was associated with AF, as well as AF-related stroke. CONCLUSIONS: These findings identify a novel role for LNK in the pathophysiology of AF in both experimental mice and in humans. Moreover, reactive lipid dicarbonyls are critical to the inflammatory AF substrate in Lnk-/- mice and mediate the proarrhythmic effects of pro-inflammatory cytokines, primarily through electrical remodeling.

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.

Endothelial mechanical stretch regulates the immunological synapse interface of renal endothelial cells in a sex-dependent manner.

Increased mechanical endothelial cell stretch contributes to the development of numerous cardiovascular and renal pathologies. Recent studies have shone a light on the importance of sex-dependent inflammation in the pathogenesis of renal disease states. The endothelium plays an intimate and critical role in the orchestration of immune cell activation through upregulation of adhesion molecules and secretion of cytokines and chemokines. While endothelial cells are not recognized as professional antigen-presenting cells, in response to cytokine stimulation, endothelial cells can express both major histocompatibility complex (MHC) I and MHC II. MHCs are essential to forming a part of the immunological synapse interface during antigen presentation to adaptive immune cells. Whether MHC I and II are increased under increased mechanical stretch is unknown. Due to hypertension being multifactorial, we hypothesized that increased mechanical endothelial stretch promotes the regulation of MHCs and key costimulatory proteins on mouse renal endothelial cells (MRECs) in a stretch-dependent manner. MRECs derived from both sexes underwent 5%, 10%, or 15% uniaxial cyclical stretch, and immunological synapse interface proteins were determined by immunofluorescence microscopy, immunoblot analysis, and RNA sequencing. We found that increased endothelial mechanical stretch conditions promoted downregulation of MHC I in male MRECs but upregulation in female MRECs. Moreover, MHC II was upregulated by mechanical stretch in both male and female MRECs, whereas CD86 and CD70 were regulated in a sex-dependent manner. By bulk RNA sequencing, we found that increased mechanical endothelial cell stretch promoted differential gene expression of key antigen processing and presentation genes in female MRECs, demonstrating that females have upregulation of key antigen presentation pathways. Taken together, our data demonstrate that mechanical endothelial stretch regulates endothelial activation and immunological synapse interface formation in renal endothelial cells in a sex-dependent manner.NEW & NOTEWORTHY Endothelial cells contribute to the development of renal inflammation and have the unique ability to express antigen presentation proteins. Whether increased endothelial mechanical stretch regulates immunological synapse interface proteins remains unknown. We found that antigen presentation proteins and costimulatory proteins on renal endothelial cells are modulated by mechanical stretch in a sex-dependent manner. Our data provide novel insights into the sex-dependent ability of renal endothelial cells to present antigens in response to endothelial mechanical stimuli.

Cardiac and vascular complications in lupus: Is there a role for sex?

Systemic lupus erythematosus (SLE) is a common systemic autoimmune disorder and is characterized by autoantibody formation and subsequent immune complex deposition into target organs. SLE affects nearly nine women to every one man worldwide. Patients with SLE are at an enhanced risk for cardiovascular disease (CVD) morbidity and mortality. CVD is the leading cause of death worldwide and includes heart and blood vessel disorders, cerebrovascular disease, and rheumatic heart disease. Specific mechanisms by which cardiac and vascular pathophysiology develops in patients with SLE are still not fully known. Not only do we not understand this correlation between SLE and CVD, but there is also a critical gap in scientific knowledge on the contribution of sex. In this review, we will discuss the cardiac and vascular pathological disease states that are present in some patients with SLE. More importantly, we will discuss the potential mechanisms for the role of sex and sex hormones in the development of CVD with SLE.

A novel functional role for the classic CNS neurotransmitters, GABA, glycine, and glutamate, in the kidney: potent and opposing regulators of the renal vasculature.

The presence of a renal GABA/glutamate system has previously been described; however, its functional significance in the kidney remains undefined. We hypothesized, given its extensive presence in the kidney, that activation of this GABA/glutamate system would elicit a vasoactive response from the renal microvessels. The functional data here demonstrate, for the first time, that activation of endogenous GABA and glutamate receptors in the kidney significantly alters microvessel diameter with important implications for influencing renal blood flow. Renal blood flow is regulated in both the renal cortical and medullary microcirculatory beds via diverse signaling pathways. GABA- and glutamate-mediated effects on renal capillaries are strikingly similar to those central to the regulation of central nervous system capillaries, that is, exposing renal tissue to physiological concentrations of GABA, glutamate, and glycine led to alterations in the way that contractile cells, pericytes, and smooth muscle cells, regulate microvessel diameter in the kidney. Since dysregulated renal blood flow is linked to chronic renal disease, alterations in the renal GABA/glutamate system, possibly through prescription drugs, could significantly impact long-term kidney function.NEW & NOTEWORTHY Functional data here offer novel insight into the vasoactive activity of the renal GABA/glutamate system. These data show that activation of endogenous GABA and glutamate receptors in the kidney significantly alters microvessel diameter. Furthermore, the results show that these antiepileptic drugs are as potentially challenging to the kidney as nonsteroidal anti-inflammatory drugs.

Novel Concepts in Nephron Sodium Transport: A Physiological and Clinical Perspective.

The kidneys play a critical role in maintaining total body sodium (Na+) balance across a wide range of dietary intake, accomplished by a concerted effort involving multiple Na+ transporters along the nephron. Furthermore, nephron Na+ reabsorption and urinary Na+ excretion are closely linked to renal blood flow and glomerular filtration such that perturbations in either of them can modify Na+ transport along the nephron, ultimately resulting in hypertension and other Na+-retentive states. In this article, we provide a brief physiological overview of nephron Na+ transport and illustrate clinical syndromes and therapeutic agents that affect Na+ transporter function. We highlight recent advances in kidney Na+ transport, particularly the role of immune cells, lymphatics, and interstitial Na+ in regulating Na+ reabsorption, the emergence of potassium (K+) as a regulator of Na+ transport, and the evolution of the nephron to modulate Na+ transport.

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.

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.

Endothelial cells: potential novel regulators of renal inflammation.

Substantial evidence has supported the role of endothelial cell (EC) activation and dysfunction in the development of hypertension, chronic kidney disease (CKD), and lupus nephritis (LN). In both humans and experimental models of hypertension, CKD, and LN, ECs become activated and release potent mediators of inflammation including cytokines, chemokines, and reactive oxygen species that cause EC dysfunction, tissue damage, and fibrosis. Factors that activate the endothelium include inflammatory cytokines, mechanical stretch, and pathological shear stress. These signals can activate the endothelium to promote upregulation of adhesion molecules, such as intercellular adhesion molecule-1 and vascular cell adhesion molecule-1, which promote leukocyte adhesion and migration to the activated endothelium. More importantly, it is now recognized that some of these signals may in turn promote endothelial antigen presentation through major histocompatibility complex II. In this review, we will consider in-depth mechanisms of endothelial activation and the novel mechanism of endothelial antigen presentation. Moreover, we will discuss these proinflammatory events in renal pathologies and consider possible new therapeutic approaches to limit the untoward effects of endothelial inflammation in hypertension, CKD, and LN.

Innate immunity and clinical hypertension.

Emerging evidence has supported a role of inflammation and immunity in the genesis of hypertension. In humans and experimental models of hypertension, cells of the innate and adaptive immune system enter target tissues, including vessels and the kidney, and release powerful mediators including cytokines, matrix metalloproteinases and reactive oxygen species that cause tissue damage, fibrosis and dysfunction. These events augment the blood pressure elevations in hypertension and promote end-organ damage. Factors that activate immune cells include sympathetic outflow, increased sodium within microenvironments where these cells reside, and signals received from the vasculature. In particular, the activated endothelium releases reactive oxygen species and interleukin (IL)-6 which in turn stimulate transformation of monocytes to become antigen presenting cells and produce cytokines like IL-1ß and IL-23, which further affect T cell function to produce IL-17A. Genetic deletion or neutralization of these cytokines ameliorates hypertension and end-organ damage. In this review, we will consider in depth features of the hypertensive milieu that lead to these events and consider new treatment approaches to limit the untoward effects of inflammation in hypertension.

Growth Arrest Specific-6 and Axl Coordinate Inflammation and Hypertension.

[Figure: see text].

Hypertension: Do Inflammation and Immunity Hold the Key to Solving this Epidemic?

Elevated cardiovascular risk including stroke, heart failure, and heart attack is present even after normalization of blood pressure in patients with hypertension. Underlying immune cell activation is a likely culprit. Although immune cells are important for protection against invading pathogens, their chronic overactivation may lead to tissue damage and high blood pressure. Triggers that may initiate immune activation include viral infections, autoimmunity, and lifestyle factors such as excess dietary salt. These conditions activate the immune system either directly or through their impact on the gut microbiome, which ultimately produces chronic inflammation and hypertension. T cells are central to the immune responses contributing to hypertension. They are activated in part by binding specific antigens that are presented in major histocompatibility complex molecules on professional antigen-presenting cells, and they generate repertoires of rearranged T-cell receptors. Activated T cells infiltrate tissues and produce cytokines including interleukin 17A, which promote renal and vascular dysfunction and end-organ damage leading to hypertension. In this comprehensive review, we highlight environmental, genetic, and microbial associated mechanisms contributing to both innate and adaptive immune cell activation leading to hypertension. Targeting the underlying chronic immune cell activation in hypertension has the potential to mitigate the excess cardiovascular risk associated with this common and deadly disease.

The role of inflammation in hypertension: novel concepts.

Hypertension remains the most important modifiable risk factor for the development of cardiovascular disease. While it is clear that inflammation plays a pivotal role in the development and maintenance of hypertension, several novel discoveries have been made within the past decade that have advanced the field and have provided new mechanistic insights. First, recent studies have identified a central role of sodium-induced immune cell activation in the pathogenesis of hypertension by altering the gut microbiome and formation of products of lipid oxidation known as isolevuglandins. Second, cytokine elaboration by the inflammasome leading to end-organ dysfunction and immune activation has been found to play a role in the genesis of hypertension. Third, novel techniques have identified previously uncharacterized immune cell populations that may play a functional role in these processes. Finally, the role of inflammation in hypertension may be an important mediator of severe COVID-19 infections. In this review, we discuss these recent advances in the study of inflammation and hypertension and highlight topics for future studies.

ENaC in Salt-Sensitive Hypertension: Kidney and Beyond.

PURPOSE OF REVIEW: The main goal of this article is to discuss the role of the epithelial sodium channel (ENaC) in extracellular fluid and blood pressure regulation. RECENT FINDINGS: Besides its role in sodium handling in the kidney, recent studies have found that ENaC expressed in other cells including immune cells can influence blood pressure via extra-renal mechanisms. Dendritic cells (DCs) are activated and contribute to salt-sensitive hypertension in an ENaC-dependent manner. We discuss recent studies on how ENaC is regulated in both the kidney and other sites including the vascular smooth muscles, endothelial cells, and immune cells. We also discuss how this extra-renal ENaC can play a role in salt-sensitive hypertension and its promise as a novel therapeutic target. The role of ENaC in blood pressure regulation in the kidney has been well studied. Recent human gene sequencing efforts have identified thousands of variants among the genes encoding ENaC, and research efforts to determine if these variants and their expression in extra-renal tissue play a role in hypertension will advance our understanding of the pathogenesis of ENaC-mediated cardiovascular disease and lead to novel therapeutic targets.

Antagonism of major histocompatibility complex class II invariant chain peptide during chronic lipopolysaccharide treatment rescues autoregulatory behavior.

Toll-like receptor 4 (TLR4) activation contributes to vascular dysfunction in pathological conditions such as hypertension and diabetes, but the role of chronic TLR4 activation on renal autoregulatory behavior is unknown. We hypothesized that subclinical TLR4 stimulation with low-dose lipopolysaccharide (LPS) infusion increases TLR4 activation and blunts renal autoregulatory behavior. We assessed afferent arteriolar autoregulatory behavior in male Sprague-Dawley rats after prolonged LPS (0.1 mg·kg-1·day-1 sq) infusion via osmotic minipump for 8 or 14 days. Some rats also received daily cotreatment with either anti-TLR4 antibody (1 µg ip), competitive antagonist peptide (CAP; 3 mg/kg ip) or tempol (2 mmol/l, drinking water) throughout the 8-day LPS treatment period. Autoregulatory behavior was assessed using the in vitro blood-perfused juxtamedullary nephron preparation. Selected physiological measures, systolic blood pressure and baseline diameters were normal and similar across groups. Pressure-dependent vasoconstriction averaged 72 ± 2% of baseline in sham rats, indicating intact autoregulatory behavior. Eight-day LPS-treated rats exhibited significantly impaired pressure-mediated vasoconstriction (96 ± 1% of baseline), whereas it was preserved in rats that received anti-TLR4 antibody (75 ± 3%), CAP (84 ± 2%), or tempol (82 ± 2%). Using a 14-day LPS (0.1 mg·kg-1·day-1 sq) intervention protocol, CAP treatment started on day 7, where autoregulatory behavior is already impaired. Systolic blood pressures were normal across all treatment groups. Fourteen-day LPS treatment retained the autoregulatory impairment (95 ± 2% of baseline). CAP intervention starting on day 7 rescued pressure-mediated vasoconstriction with diameters decreasing to 85 ± 1% of baseline. These data demonstrate that chronic subclinical TLR4 activation impairs afferent arteriolar autoregulatory behavior through mechanisms involving reactive oxygen species and major histocompatibility complex class II activation.

High Salt Activates CD11c+ Antigen-Presenting Cells via SGK (Serum Glucocorticoid Kinase) 1 to Promote Renal Inflammation and Salt-Sensitive Hypertension.

Salt-sensing mechanisms in hypertension involving the kidney, vasculature, and central nervous system have been well studied; however, recent studies suggest that immune cells can sense sodium (Na+). Antigen-presenting cells (APCs) including dendritic cells critically modulate inflammation by activating T cells and producing cytokines. We recently found that Na+ enters dendritic cells through amiloride-sensitive channels including the α and γ subunits of the epithelial sodium channel (ENaC) and mediates nicotinamide adenine dinucleotide phosphate oxidase-dependent formation of immunogenic IsoLG (isolevuglandin)-protein adducts leading to inflammation and hypertension. Here, we describe a novel pathway in which the salt-sensing kinase SGK1 (serum/glucocorticoid kinase 1) in APCs mediates salt-induced expression and assembly of ENaC-α and ENaC-γ and promotes salt-sensitive hypertension by activation of the nicotinamide adenine dinucleotide phosphate oxidase and formation of IsoLG-protein adducts. Mice lacking SGK1 in CD11c+ cells were protected from renal inflammation, endothelial dysfunction, and developed blunted hypertension during the high salt feeding phase of the N-Nitro-L-arginine methyl ester hydrochloride/high salt model of salt-sensitive hypertension. CD11c+ APCs treated with high salt exhibited increased expression of ENaC-γ which coimmunoprecipitated with ENaC-α. This was associated with increased activation and expression of various nicotinamide adenine dinucleotide phosphate oxidase subunits. Genetic deletion or pharmacological inhibition of SGK1 in CD11c+ cells prevented the high salt-induced expression of ENaC and nicotinamide adenine dinucleotide phosphate oxidase. These studies indicate that expression of SGK1 in CD11c+ APCs contributes to the pathogenesis of salt-sensitive hypertension.

High dietary salt-induced dendritic cell activation underlies microbial dysbiosis-associated hypertension.

Excess dietary salt contributes to inflammation and hypertension via poorly understood mechanisms. Antigen presenting cells including dendritic cells (DCs) play a key role in regulating intestinal immune homeostasis in part by surveying the gut epithelial surface for pathogens. Previously, we found that highly reactive γ-ketoaldehydes or isolevuglandins (IsoLGs) accumulate in DCs and act as neoantigens, promoting an autoimmune-like state and hypertension. We hypothesized that excess dietary salt alters the gut microbiome leading to hypertension and this is associated with increased immunogenic IsoLG-adduct formation in myeloid antigen presenting cells. To test this hypothesis, we performed fecal microbiome analysis and measured blood pressure of healthy human volunteers with salt intake above or below the American Heart Association recommendations. We also performed 16S rRNA analysis on cecal samples of mice fed normal or high salt diets. In humans and mice, high salt intake was associated with changes in the gut microbiome reflecting an increase in Firmicutes, Proteobacteria and genus Prevotella bacteria. These alterations were associated with higher blood pressure in humans and predisposed mice to vascular inflammation and hypertension in response to a sub-pressor dose of angiotensin II. Mice fed a high salt diet exhibited increased intestinal inflammation including the mesenteric arterial arcade and aorta, with a marked increase in the B7 ligand CD86 and formation of IsoLG-protein adducts in CD11c+ myeloid cells. Adoptive transfer of fecal material from conventionally housed high salt-fed mice to germ-free mice predisposed them to increased intestinal inflammation and hypertension. These findings provide novel insight into the mechanisms underlying inflammation and hypertension associated with excess dietary salt and may lead to interventions targeting the microbiome to prevent and treat this important disease.