Abstract P418: Antigen-presenting Cell-specific MAP-kinase Signaling Contributes To Inflammation And Salt-sensitivity Of Blood Pressure In Humans

Abstract

Salt-sensitivity of blood pressure (SSBP) is defined by the changes in blood pressure in concert with salt intake/depletion. SSBP affects 50 percent of hypertensive and 25 percent of normotensive individuals and is an independent risk for stroke and cardiovascular death in both groups. We recently found that phosphorylation of STAT3 and SMAD3 in antigen-presenting cells plays an important role in developing SSBP. We hypothesized that mitogen-activated protein kinases (MAPKs) signaling plays an important role in activating/phosphorylating JAK-STAT-SMAD and contributes to salt-sensitivity of blood pressure. We isolated monocytes from eleven healthy individuals and treated them with either normal salt (NS) or high salt (HS) and performed bulk-RNA-sequencing. The bulk-RNA transcriptomic data analysis suggested that out of 21 members of the MAPK family, eighteen were upregulated (1.7-fold) in monocytes exposed to high salt. Among these, MAPK7 (NS:818.18±54.96; HS:1473.18±151.50) and MAPKAPK2 (NS:3977.81±286.67; HS:6222.63±440.32) were significantly upregulated. In additional experiments, we enrolled eleven hypertensive patients and phenotyped them for salt-sensitivity using a rapid salt-load and depletion inpatient protocol. Blood was collected at baseline, after salt loading, and depletion, and CITE-Seq was performed on isolated PBMCs. The data analysis showed that MAPK7 and MAPKAPK2 expressions mirror the blood pressure changes following salt loading and depletion in salt-sensitive but not in salt-resistant patients. Moreover, we found a positive correlation between MAPKAPK2 expression and the pulse pressure ((PP) r=0.52, p=0.033) after salt-load. Epoxyeicosatrienoic acid (EET) has been shown to activate MAPKs resulting in inhibiting ENAC activity. The data showed a strong positive correlation between MAPK7 expression and levels of EETs in plasma (r=0.70, p=0.036), and urine (r=0.68, p=0.045) after salt-load. These results from bulk-RNA and single-cell CITE-Seq data indicate that MAPKs play an important role in human SSBP.