Impact of renin angiotensin system blockade on renal function in health and disease: an end or a beginning?

Acute renal injury events in diabetic patients treated with SGLT2 inhibitors: A comprehensive review with a special reference to RAAS blockers

Renin-angiotensin-aldosterone system (RAAS) blockers and sodium-glucose cotransporter type 2 inhibitors (SGLT2is) are two pharmacological classes that proved a remarkable nephroprotective effect, yet a risk of acute kidney injury (AKI) was also pointed out. In 2016, the US Food and Drug Administration recommended caution with the concomitant use of these medications. While the literature devoted to RAAS blockers remained surprisingly limited, numerous articles were published in recent years with SGLT2is. Safety analyses of large prospective cardiorenal trials showed a reduced rather than an increased number of AKI events in patients with type 2 diabetes treated with SGLT2is compared with those treated with placebo, despite the fact that a majority of patients received RAAS blockers at baseline. Interestingly, retrospective observational studies confirmed these reassuring findings in real-life conditions in more heterogeneous and possibly more frailty populations also commonly treated with RAAS blockers by showing a reduced risk of AKI with SGLT2is compared with other glucose-lowering drugs. Currently, there are no evidence of an increased risk of AKI with RAAS blocker-SGLT2i combinations in absence of haemodynamic instability. Several underlying mechanisms could explain a decreased rather than an increased risk of AKI with SGLT2is, including in patients treated with RAAS blockers.

C-peptide as a Therapy for Kidney Disease: A Systematic Review and Meta-Analysis

C-peptide has intrinsic biological activity and may be renoprotective. We conducted a systematic review to determine whether C-peptide had a beneficial effect on renal outcomes. MEDLINE, EMBASE, and the Cochrane Central Databases were searched for human and animal studies in which C-peptide was administered and renal endpoints were subsequently measured. We identified 4 human trials involving 74 patients as well as 18 animal studies involving 35 separate experiments with a total of 641 animals. In humans, the renal effects of exogenously delivered C-peptide were only studied in type 1 diabetics with either normal renal function or incipient nephropathy. Pooled analysis showed no difference in GFR (mean difference, -1.36 mL/min/1.73 m2, p = 0.72) in patients receiving C-peptide compared to a control group, but two studies reported a reduction in glomerular hyperfiltration (p<0.05). Reduction in albuminuria was also reported in the C-peptide group (p<0.05). In diabetic rodent models, C-peptide led to a reduction in GFR (mean difference, -0.62 mL/min, p<0.00001) reflecting a partial reduction in glomerular hyperfiltration. C-peptide also reduced proteinuria (mean difference, -186.25 mg/day, p = 0.05), glomerular volume (p<0.00001), and mesangial matrix area (p<0.00001) in diabetic animals without affecting blood pressure or plasma glucose. Most studies were relatively short-term in duration, ranging from 1 hour to 3 months. Human studies of sufficient sample size and duration are needed to determine if the beneficial effects of C-peptide seen in animal models translate into improved long-term clinical outcomes for patients with chronic kidney disease. (PROSPERO CRD42014007472)

Clinicopathological assessment of the nephron number

Recent studies have demonstrated much larger variability in the total number of nephrons in normal populations than previously suspected. In addition, it has been suggested that individuals with a low nephron number may have an increased lifetime risk of hypertension or renal insufficiency, emphasizing the importance of evaluating the nephron number in each individual. In view of the fact that all previous reports of the nephron number were based on analyses of autopsy kidneys, the identification of surrogate markers detectable in living subjects is needed in order to enhance understanding of the clinical significance of this parameter. In this review, we summarize the clinicopathological factors and findings indicating a reduction in the nephron number, focusing particularly on those found at the time of a preserved renal function.

Hypertension in the Elderly

Elderly individuals with hypertension show specific characteristics as a result of advancing arteriosclerosis, a high frequency of isolated systolic hypertension, increased pulse pressure and orthostatic hypotension. The necessity to treat hypertension in the elderly, including isolated systolic hypertension, has been demonstrated in many large-scale intervention trials. Young-old (65-74 years of age) hypertensive patients should be treated the same as nonelderly hypertensive patients. In old-old (75-84 years of age) patients with mild hypertension (140-159/90-99 mm Hg), the recommended target blood pressure (BP) is <140/90 mm Hg. In old-old (75-84 years of age) and oldest-old (> or =85 years of age) patients with systolic BP > or =160 mm Hg, cautious treatment is required. An intermediate target BP of <150 mm Hg is appropriate, followed by a final target BP of <140 mm Hg, if tolerated. Nonmedical therapy, such as salt restriction, exercise and weight reduction, is useful in the elderly. However, individualised management of nonmedical therapy is necessary to avoid deterioration of quality of life resulting from strict management of the patient's lifestyle. Diuretics, calcium channel antagonists, ACE inhibitors and angiotensin II type 1 receptor antagonists have been established as first-line antihypertensive drugs in the elderly. Use of combination therapy helps to achieve target BPs. The starting dose of each drug should be half the usual dose for nonelderly patients, and may be increased at intervals of >4 weeks, with achievement of the target BP in 3-6 months or longer. In hypertensive patients with co-morbid diseases, the target BP should be determined individually and antihypertensive drugs selected bearing in mind the patient's clinical circumstances. Avoiding hypoperfusion of target organs is very important in elderly hypertensive patients. When treating hypertension in elderly patients, the approach should be to identify individual pathophysiological characteristics and lower the BP cautiously and slowly.

Antiproteinuric effect of RAS blockade: New mechanisms

Experimental and clinical studies have shown that blockade of the renin-angiotensin system (RAS) is effective in reducing proteinuria in conditions such as diabetes by reducing systemic and intraglomerular hydrostatic pressure. However, increasing evidence suggests that nonhemodynamic effects, such as preservation of the podocyte slit diaphragm structure and function, may also mediate the antiproteinuric effects of RAS blockade. In this review, we analyze in detail the evidence for known and novel mechanisms considered to play important roles in mediating the antiproteinuric effect of RAS blockers, with a particular focus on diabetic nephropathy.