Clinical Study of UMOD NKCC2 Interaction on Salt-sensitivity in Hypertension

There are over 1 billion people with HTN worldwide, and the World Health Organisation suggests this will rise to 1.5 billion by 2020.(1) Up to 30% of hypertensive patients have resistant HTN (uncontrolled BP on \> 3 drugs of which one must be a diuretic) and \~50% have uncontrolled HTN, with a 7-fold higher cardiovascular risk. In clinical practice, criteria such as ancestry and serum renin levels provide only a rough indication of the underlying disease pathway and, while pharmacotherapy is the mainstay of HTN management, the selection of antihypertensive therapy is essentially by trial-and-error. Five drug classes are the main first-line agents for HTN, but response rates to any given drug are only \~50%. There are no new anti-hypertensive drugs in clinical trials and there is a need to either develop newer agents or target existing drugs to specific strata of hypertensive patients in whom they would be beneficial. The recent failure of the Renal Sympathetic Denervation trial, which used a novel device strategy for resistant HTN, highlights the limited options available in the management of uncontrolled or resistant HTN. HTN as a phenotype demonstrates stratification in the population, based on the specific pathophysiological and molecular pathways that are operative and this is reflected in the current NICE guidelines. However, there has been little progress in stratification by leveraging genomic and molecular information, although there is evidence that this may be useful. Monogenic forms of HTN show that identification of the many causative mutations, primarily affecting the kidney and sodium balance, can inform therapy - for example, glucocorticoids in glucocorticoid remediable aldosteronism and amiloride in Liddle syndrome. Despite the successful adoption of the BHS/NICE treatment algorithm for the treatment of HTN, there remains substantial clinical uncertainty about the preferred clinical management of people with uncontrolled or treatment resistant HTN. Moreover, the choice of diuretic, suggested in HTN guidelines, is not based on clinical trials for third line antihypertensive agents. There is general consensus that resistant HTN is due to excessive sodium retention and thus "further diuretic therapy" may be an effective treatment. The choice that one type of diuretic will be superior to another has however not been studied and is usually prescribed in a trial and error manner with diuretics that primarily target the distal nephron (thiazide-like diuretic or spironolactone).