Therapeutic Renin Inhibition in Diabetic Nephropathy-A Review of the Physiological Evidence

The purpose of this systematic review was to investigate the scientific evidence to support the use of direct renin inhibitors (DRIs) in diabetic nephropathy (DN). MEDLINE was searched for articles reported until 2018. A standardized dataset was extracted from articles describing the effects of DRIs on plasma renin activity (PRA) in DN. A total of three clinical articles studying PRA as an outcome measure for DRIs use in DN were identified. These clinical studies were randomized controlled trials (RCTs): one double-blind crossover, one post hoc of a double-blind and placebo-controlled study, and one open-label and parallel-controlled study. Two studies reported a significant decrease of albuminuria associated with PRA reduction. One study had a DRI as monotherapy compared with placebo, and two studies had DRI as add-in to an angiotensin II (Ang II) receptor blocker (ARB). Of 10,393 patients with DN enrolled in five studies with DRI, 370 (3.6%) patients had PRA measured. Only one preclinical study was identified that determined PRA when investigating the effects of aliskiren in DN. Moreover, most of observational preclinical and clinical studies identified report on a low PRA or hyporeninemic hypoaldosteronism in DM. Renin inhibition has been suggested for DN, but proof-of-concept studies for this are scant. A small number of clinical and preclinical studies assessed the PRA effects of DRIs in DN. For a more successful translational research for DRIs, specific patient population responsive to the treatment should be identified, and PRA may remain a biomarker of choice for patient stratification.

Aliskiren: Preclinical evidence for the treatment of hyperproliferative skin disorders

Psoriasis is a complex inflammatory and hyperproliferative skin disease. The pathogenesis and mechanisms involved are not completely understood, which makes treatment a difficult issue. Angiotensin II, the most active peptide of the renin-angiotensin system, seems to be involved in processes related to psoriasis pathogenesis, such as inflammation and cell proliferation. The aim of this study was to investigate the influence of renin inhibition on inflammation parameters and keratinocyte proliferation in a mouse model of chronic skin inflammation induced by croton oil. Aliskiren had anti-inflammatory effects by reducing levels of tumor necrosis factor-α and interleukin -6, and by inhibiting myeloperoxidase activity. Aliskiren also showed antiproliferative activity by reducing epidermal hyperplasia and proliferating cell nuclear antigen levels. Aliskiren treatment did not induce alterations in the cardiovascular system, normal skin thickness, and organ weight. These results suggest that aliskiren could be a valuable tool to be incorporated in the treatment of hyperproliferative and inflammatory skin disorders such as psoriasis.

Wnt/β-catenin signaling and renin-angiotensin system in chronic kidney disease

PURPOSE OF REVIEW

Intrarenal activation of the renin-angiotensin system (RAS) plays an essential role in the pathogenesis of hypertension and chronic kidney diseases (CKD). However, how RAS genes are regulated in vivo was poorly understood until recently. This review focuses on recent findings of the transcriptional regulation of RAS components, as well as their implication in developing novel strategies to treat the patients with CKD.

RECENT FINDINGS

Bioinformatics analyses have uncovered the presence of putative binding sites for T-cell factor/β-catenin in the promoter region of all RAS genes. Both in-vitro and in-vivo studies confirm that Wnt/β-catenin is the master upstream regulator that controls the expression of all RAS components tested, such as angiotensinogen, renin, angiotensin converting enzyme and the angiotensin II type I receptor in the kidney. Targeted inhibition of Wnt/β-catenin, by either small molecule ICG-001 or endogenous Wnt antagonist Klotho, represses RAS activation and ameliorates proteinuria and kidney injury. Blockade of Wnt/β-catenin signaling also normalizes blood pressure in a mouse model of CKD.

SUMMARY

These recent studies identify Wnt/β-catenin as the master regulator that controls multiple RAS genes, and suggest that targeting this upstream signaling could be an effective strategy for the treatment of patients with hypertension and CKD.