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SH2B3 (SH2B adaptor protein 3) is an adaptor protein that negatively regulates cytokine signaling and cell proliferation. A common missense single nucleotide polymorphism inWe used CRISPR-Cas9 technology to create mice homozygous for the major (Arg/Arg) and minor (Trp/Trp) alleles of thisTrp/Trp mice exhibit 10 mmHg higher systolic BP during chronic Ang II infusion compared to Arg/Arg controls. Renal injury and perivascular fibrosis are exacerbated in Trp/Trp mice compared to Arg/Arg controls following Ang II infusion. Renal and ex vivo stimulated splenic CD8Taken together, these results suggest that the Trp encoding allele of rs3184504 is causal for BP elevation and renal dysfunction, in part through loss of SH2B3-mediated repression of T cell IL-12 signaling leading to enhanced IFNg production.

Background: SH2B3 (SH2B adaptor protein 3) is an adaptor protein that negatively regulates cytokine signaling and cell proliferation. A common missense single nucleotide polymorphism in SH2B3 (rs3184504) results in substitution of tryptophan (Trp) for arginine (Arg) at amino acid 262 and is a top association signal for hypertension in human genome-wide association studies. Whether this variant is causal for hypertension, and if so, the mechanism by which it impacts pathogenesis is unknown. Methods: We used CRISPR-Cas9 technology to create mice homozygous for the major (Arg/Arg) and minor (Trp/Trp) alleles of this SH2B3 polymorphism. Mice underwent angiotensin II (Ang II) infusion to evaluate differences in blood pressure (BP) elevation and end-organ damage including albuminuria and renal fibrosis. Cytokine production and Stat4 phosphorylation was also assessed in Arg/Arg and Trp/Trp T cells. Results: Trp/Trp mice exhibit 10 mmHg higher systolic BP during chronic Ang II infusion compared to Arg/Arg controls. Renal injury and perivascular fibrosis are exacerbated in Trp/Trp mice compared to Arg/Arg controls following Ang II infusion. Renal and ex vivo stimulated splenic CD8 + T cells from Ang II-infused Trp/Trp mice produce significantly more interferon gamma (IFNg) compared to Arg/Arg controls. Interleukin-12 (IL-12)-induced IFNg production is greater in Trp/Trp compared to Arg/Arg CD8 + T cells. In addition, IL-12 enhances Stat4 phosphorylation to a greater degree in Trp/Trp compared to Arg/Arg CD8 + T cells, suggesting that Trp-encoding SH2B3 exhibits less negative regulation of IL-12 signaling to promote IFNg production. Finally, we demonstrated that a multi-SNP model genetically predicting increased SH2B3 expression in lymphocytes is inversely associated with hypertension and hypertensive chronic kidney disease in humans.. Conclusions: Taken together, these results suggest that the Trp encoding allele of rs3184504 is causal for BP elevation and renal dysfunction, in part through loss of SH2B3-mediated repression of T cell IL-12 signaling leading to enhanced IFNg production.

Rationale: There is an intimate relationship between the endothelium and monocytes, and activated endothelial cells promote monocyte transformation to macrophages and dendritic cells (DCs). Recently, a subset of human DCs expressing the receptor tyrosine kinase, Axl and the lectin siglec-6 has been described and termed (AS) DCs. Objective: We sought to determine if circulating AS DCs are increased in human hypertension and to examine how Axl signaling contributes to this disease. Methods and Results: We demonstrated that circulating AS DCs are increased in hypertensive humans compared with normotensive controls. Pulse pressure in humans also correlated with plasma levels of the Axl agonist GAS6 (growth arrest specific 6). Exposure of human endothelial cells to 10% cyclical stretch increased release of the GAS6, promoted Axl signaling and caused AS DC formation; events that were inhibited by blockade of Axl with R428 or by siRNA knockdown of either endothelial GAS6 or Axl. GAS6/Axl signaling in human monocytes potentiated interleukin 1β production through NLRP3 (nucleotide-binding oligomerization domain, leucine rich tepeat and pyrin domain containing protein)/caspase-1 and caused accumulation of immunogenic isoLG (isolevuglandin)-protein adducts. In mice, the Axl inhibitor R428 or global deletion of Axl attenuated hypertension and renal inflammation caused by Ang II (angiotensin II) infusion. Bone marrow transplant studies demonstrated a role of both stromal and immunologic Axl in Ang II–induced hypertension. Lastly, in freshly harvested human endothelial cells, a striking correlation was observed between the degree of endothelial cell activation as reflected by ICAM-1 (intracellular adhesion molecule 1), isoLG-adduct accumulation, and intracellular GAS6 levels. Conclusions: We define a previously unrecognized interaction of human endothelial cells and monocytes that promote formation of AS DCs in hypertension and show a critical role of GAS6 and Axl signaling in both immune cells and endothelial cells. This pathway is potentially a novel therapeutic target to reduce inflammation and end organ damage in hypertension.

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.