Identification of mechano versus chemo-sensitive renal sensory neurons in hypertension

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ABSTRACT Renal denervation lowers arterial blood pressure in multiple clinical trials and experimental animal models of hypertension. These anti-hypertensive effects have been partly attributed to the removal of renal sensory nerves as selective denervation of renal sensory nerves lowers arterial blood pressure to the same extent as total renal denervation. Despite our current knowledge of renal nerves, there is a severe lack of anatomical, functional, and mechanistic knowledge about the specific sensory fiber-types responsible for cardiovascular control. Renal sensory nerves detect mechanical and chemical stimuli within the kidneys and consequently alter sodium reabsorption, renin secretion, and sympathetic outflow. These responses are dependent on mechano- and chemo- sensitive nerve fibers which have not been clearly defined. Our preliminary data using single-cell transcriptomics on renal sensory neurons demonstrates the existence of two distinct populations: the mechanosensitive channel Piezo2 and chemosensitive channel TRPV1. The overall hypothesis of this proposal is that neurochemically distinct populations of renal sensory neurons expressing Piezo2 and TRPV1 mediate mechano- and chemo-sensitive responses in the kidney. The neurochemical profile of these neurons switches in renal stenosis from a loss of Piezo2-mechanosensitive fibers to robust expression and increased sensitivity of TRPV1-chemosensitive fibers to elevated sympathetic outflow and arterial blood pressure. Aim 1 will employ in vivo single-unit recordings, single-cell transcriptomics (>40 sensory genes), and optogenetics to determine the extent by which Piezo2 and TRPV1-expressing neurons represent mechano- and chemo- sensitive renal sensory nerve populations. Aim 2 will determine how hypertension produced by renal stenosis alters the mechano- versus chemosensitivity of renal afferents, the neurochemical profile of sensory neurons, and the sensory innervation of the kidney. Aim 3 will directly assess the contribution of Piezo2 versus TRPV1 renal sensory fibers and channels to renal sensory function and renovascular hypertension. This proposal will define, for the first time, the neurochemical and functional phenotype of renal sensory nerve populations involved in the control of arterial blood pressure, anatomically map innervation sites in the kidney, and functionally test distinct renal afferent fibers populations and channels in vivo that have a pathological role of hypertension.