Emerging drugs for chronic kidney disease

Reno-protective effects of Phosphodiesterase 5 inhibitors

The kidneys are vital organs that play an important role in removing waste materials from the blood, electrolyte balance, blood pressure regulation, and red blood cell genesis. Kidney disease can be caused by various factors, including diabetes, ischemia/reperfusion injury, and nephrotoxic agents. Inflammation and oxidative stress play a key role in the progression and pathogenesis of kidney diseases. Acute kidney injury (AKI) and chronic kidney disease (CKD) are important health problems worldwide, as they are associated with a long-term hospital stay, and increased morbidity and mortality in high-risk patients. Current standard therapeutic options are not sufficient to delay or stop the loss of kidney function. Therefore, it is necessary to develop new therapeutic options. Phosphodiesterase 5 inhibitors (PDE5Is) are a currently available class of drugs that are used to treat erectile dysfunction and pulmonary hypertension in humans. However, recent evidence suggests that PDE5Is have beneficial renoprotective effects via a variety of mechanisms. In this review, the benefits of PDE5 inhibitors in clinical conditions associated with kidney disease, such as diabetic nephropathy, ischemia-reperfusion injury, and acute and chronic kidney injury, are summarized.

Mineral and Electrolyte Disorders With SGLT2i Therapy

The newly developed sodium‐glucose cotransporter 2 inhibitors (SGLT2is) effectively modulate glucose metabolism in diabetes. Although clinical data suggest that SGLT2is (empagliflozin, dapagliflozin, ertugliflozin, canagliflozin, ipragliflozin) are safe and protect against renal and cardiovascular events, very little attention has been dedicated to the effects of these compounds on different electrolytes. As with other antidiabetic compounds, some effects on water and electrolytes balance have been documented. Although the natriuretic effect and osmotic diuresis are expected with SGLT2is, these compounds may also modulate urinary potassium, magnesium, phosphate, and calcium excretion. Notably, they have had no effect on plasma sodium levels and promoted only small increases in serum potassium and magnesium concentrations in clinical trials. Moreover, SGLT2is may induce an increase in serum phosphate, FGF‐23, and PTH; reduce 1,25‐dihydroxyvitamin D; and generate normal serum calcium. Some published and preliminary reports, as well as unconfirmed reports have suggested an association with bone fractures. Some homeostasis perturbations are transient, whereas others may persist, suggesting that the administration of SGLT2is may affect electrolyte balances in exposed subjects. Although current evidence supports their safety, additional efforts are needed to elucidate the long‐term impact of these compounds on chronic kidney disease, mineral metabolism, and bone health. Indeed, the limited follow‐up studies and the heterogeneity of the case‐mix of different randomized controlled trials preclude a definitive answer on the impact of these compounds on long‐term outcomes such as the risk of bone fracture. Here we review the current understanding of the mechanisms involved in electrolyte handling and the available data on the clinical implications of electrolytes and mineral metabolism perturbations induced by SGLT2i administration. © 2019 The Authors. JBMR Plus published by Wiley Periodicals, Inc. on behalf of American Society for Bone and Mineral Research.

New mineralocorticoid receptor antagonists: update on their use in chronic kidney disease and heart failure

Aldosterone is a mineralocorticoid hormone with a well-known effect on the renal tubule leading to water retention and potassium reabsorption. Other major effects of the hormone include the induction of proinflammatory activity that leads to progressive fibrotic damage of the target organs, heart and kidney. Blocking the aldosterone receptor therefore represents an important pharmacological strategy to avoid the clinical conditions deriving from heart failure (CHF) and chronic kidney disease (CKD). However, steroidal mineralocorticoid receptor antagonists (MRA) have a low safety profile, especially in CKD patients due to the high incidence of hyperkalemia. A new generation of nonsteroidal MRA has recently been developed to obtain a selective receptor block avoiding side-effects like hyperkalemia and thereby making the drugs suitable for administration to CKD patients. This review summarizes the results of published preclinical and clinical studies on the nonsteroidal MRA, apararenone esaxerenone and finerenone. The trials showed a better safety profile with maintained drug efficacy compared with steroidal MRA. For this reason, nonsteroidal MRA represent an interesting new therapeutic approach for the prevention of CHF and CKD progression. Some basic research findings also yielded interesting results in acute clinical settings such as myocardial infarction and acute kidney injury.

Lipocalin-2 derived from adipose tissue mediates aldosterone-induced renal injury

Lipocalin-2 is not only a sensitive biomarker, but it also contributes to the pathogenesis of renal injuries. The present study demonstrates that adipose tissue-derived lipocalin-2 plays a critical role in causing both chronic and acute renal injuries. Four-week treatment with aldosterone and high salt after uninephrectomy (ANS) significantly increased both circulating and urinary lipocalin-2, and it induced glomerular and tubular injuries in kidneys of WT mice. Despite increased renal expression of lcn2 and urinary excretion of lipocalin-2, mice with selective deletion of lcn2 alleles in adipose tissue (Adipo-LKO) are protected from ANS- or aldosterone-induced renal injuries. By contrast, selective deletion of lcn2 alleles in kidney did not prevent aldosterone- or ANS-induced renal injuries. Transplantation of fat pads from WT donors increased the sensitivity of mice with complete deletion of Lcn2 alleles (LKO) to aldosterone-induced renal injuries. Aldosterone promoted the urinary excretion of a human lipocalin-2 variant, R81E, in turn causing renal injuries in LKO mice. Chronic treatment with R81E triggered significant renal injuries in LKO, resembling those observed in WT mice following ANS challenge. Taken in conjunction, the present results demonstrate that lipocalin-2 derived from adipose tissue causes acute and chronic renal injuries, largely independent of local lcn2 expression in kidney.

Effects of cilostazol and renin-angiotensin system (RAS) blockers on the renal disease progression of Korean patients: a retrospective cohort study

Background Decline in estimated glomerular filtration rate (eGFR) is an important surrogate marker for the assessment of renal function. Addition of a second agent to angiotensin-converting-enzyme inhibitor (ACEI) or angiotensin II receptor blocker (ARB) treatment may improve current therapeutic strategies aimed at suppressing renal disease progression. Objective To determine the effect of cilostazol in combination with ACEI or ARB treatment on the decline in eGFR. Setting A tertiary hospital in Korea. Method In an observational cohort study, we analyzed 5505 patients who were prescribed ACEI or ARB and cilostazol or other antiplatelet agents. Main outcome measure The primary outcome assessed was worsening of renal function defined as a 30% decline in eGFR per year. The secondary outcomes included commencement of dialysis, renal transplantation, death, myocardial infarction, and ischemic stroke. Results Following propensity score matching, eGFR decreased over time in the majority of patients, but the decline was less in patients in the cilostazol treated (CT) group of stage 1-2 category compared to the cilostazol untreated (CU) group (OR 0.80; 95% CI 0.66-0.98). In the subgroup analysis, the strongest effect in slowing eGFR decline was observed in CT patients at a high risk of diabetes (OR 0.782; 95% CI 0.615-0.993) and the elderly (OR 0.693; 95% CI 0.504-0.953) in the stage 1-2 category. No significant increase in cardiovascular risk was observed between the CT and CU groups. Conclusion Treatment with cilostazol plus ACEI or ARB was observed to prevent worsening of renal progression in patients in the stages 1-2.

Therapeutic potential of microRNAs for the treatment of renal fibrosis and CKD

Chronic kidney disease (CKD), defined as reduced glomerular filtration rate, is increasingly becoming a major public health issue. At the histological level, renal fibrosis is the final common pathway leading to end-stage renal disease, irrespective of the initial injury. According to this view, antifibrotic agents should slow or halt the progression of CKD. However, due to multiple overlapping pathways stimulating fibrosis, it has been difficult to develop antifibrotic drugs that delay or reverse the progression of CKD. MicroRNAs (miRNAs) are small noncoding RNA molecules, 18-22 nucleotides in length, that control many developmental and cellular processes as posttranscriptional regulators of gene expression. Emerging evidence suggests that miRNAs targeted against genes involved in renal fibrosis might be potential candidates for the development of antifibrotic therapies for CKD. This review will discuss some of the miRNAs, such as Let-7, miR-21,-29, -192, -200,-324, -132, -212, -30, -126, -433, -214, and -199a, that are implicated in renal fibrosis and the potential to exploit these molecular targets for the treatment of CKD.

Emerging therapeutics for the treatment of diabetic nephropathy

Diabetic nephropathy (DN) is the most common pathology contributing to the development of chronic kidney disease (CKD). DN caused by hypertension and unmitigated inflammation in diabetics, renders the kidneys unable to perform normally, and leads to renal fibrosis and organ failure. The increasing global prevalence of DN has been directly attributed to rising incidences of Type II diabetes, and is now the largest non-communicable cause of death worldwide. Despite the high morbidity, successful new treatments for DN are lacking. This review seeks to provide new insight on emerging clinical candidates under investigation for the treatment of DN.

Phosphodiesterase type 5 inhibitors and kidney disease

Chronic kidney disease (CKD) represents a worldwide health problem. Traditionally, the nephroprotective treatment for CKD aims to slow progression to end-stage renal disease and includes dietary protein restriction, correction of metabolic acidosis, and renin-angiotensin system blockers. However, current standard therapeutic options may not be enough for preventing CKD progression in a subset of patients making necessary to develop novel therapeutic options to further slow renal function loss. Phosphodiesterase type 5 (PDE5) inhibitors represent a class of drugs traditionally used to treat erectile dysfunction and pulmonary hypertension. However, recent evidence suggests that PDE5 inhibitors may have additional therapeutic effects, such as cardioprotection and cerebrovascular protection. In the current review, we summarize PDE5 inhibitors' utility in disease states and clinical conditions related to kidney disease such as systemic hypertension and acute and chronic kidney injury and discuss the mechanisms explaining possible kidney protective roles of PDE5 inhibitors. A recently completed phase 2 trials demonstrated that the long-acting PDE5 inhibitor PF-00489791 decreased albuminuria in patients with overt diabetic nephropathy when added on top of renin-angiotensin system blockade.