Renoprotective effects of aliskiren on adenine-induced tubulointerstitial nephropathy: possible underlying mechanisms

Adrenomedullin Mitigates Doxorubicin-Induced Nephrotoxicity in Rats: Role of Oxidative Stress, Inflammation, Apoptosis, and Pyroptosis

Doxorubicin (DOX) is an anticancer antibiotic which has various effects in human cancers. It is one of the commonly known causes of drug-induced nephrotoxicity, which results in acute renal injury. Adrenomedullin (ADM), a vasodilator peptide, is widely distributed in many tissues and has potent protective effects. Therefore, the current study aimed to examine the protective potential mechanisms of ADM against DOX-induced nephrotoxicity. A total of 28 male Wistar rats were randomized into four groups: control group, doxorubicin group (15 mg/kg single intraperitoneal injection of DOX), adrenomedullin + doxorubicin group (12 μg/kg/day intraperitoneal injection of ADM) 3 days prior to DOX injection and continuing for 14 days after the model was established, and adrenomedullin group. Kidney function biomarkers, oxidative stress markers, and inflammatory mediators (TNF-α, NLRP3, IL-1β, and IL-18) were assessed. The expressions of gasdermin D and ASC were assessed by real-time PCR. Furthermore, the abundances of caspase-1 (p20), Bcl-2, and Bax immunoreactivity were evaluated. ADM administration improved the biochemical parameters of DOX-induced nephrotoxicity, significantly reduced oxidative damage markers and inflammatory mediators, and suppressed both apoptosis and pyroptosis. These results were confirmed by the histopathological findings and revealed that ADM's antioxidant, anti-inflammatory, anti-apoptotic, and anti-pyroptotic properties may have prospective applications in the amelioration of DOX-induced nephrotoxicity.

Circadian Blood Pressure Rhythm in Cardiovascular and Renal Health and Disease

Blood pressure (BP) follows a circadian rhythm, it increases on waking in the morning and decreases during sleeping at night. Disruption of the circadian BP rhythm has been reported to be associated with worsened cardiovascular and renal outcomes, however the underlying molecular mechanisms are still not clear. In this review, we briefly summarized the current understanding of the circadian BP regulation and provided therapeutic overview of the relationship between circadian BP rhythm and cardiovascular and renal health and disease.

A Review of Specific Biomarkers of Chronic Renal Injury and Their Potential Application in Nonclinical Safety Assessment Studies

A host of novel renal biomarkers have been developed over the past few decades which have enhanced monitoring of renal disease and drug-induced kidney injury in both preclinical studies and in humans. Since chronic kidney disease (CKD) and acute kidney injury (AKI) share similar underlying mechanisms and the tubulointerstitial compartment has a functional role in the progression of CKD, urinary biomarkers of AKI may provide predictive information in chronic renal disease. Numerous studies have explored whether the recent AKI biomarkers could improve upon the standard clinical biomarkers, estimated glomerular filtration rate (eGFR), and urinary albumin to creatinine ratio, for predicting outcomes in CKD patients. This review is an introduction to alternative assays that can be utilized in chronic (>3 months duration) nonclinical safety studies to provide information on renal dysfunction and to demonstrate specific situations where these assays could be utilized in nonclinical drug development. Novel biomarkers such as symmetrical dimethyl arginine, dickkopf homolog 3, and cystatin C predict chronic renal injury in animals, act as surrogates for GFR, and may predict changes in GFR in patients over time, ultimately providing a bridge from preclinical to clinical renal monitoring.

Royal Jelly and Aliskiren mutually annul their protective effects against gentamicin-induced nephrotoxicity in rats

Background and Aim

Gentamicin (GM) is one of the most effective antibiotics for severe, life-threatening Gram-negative infections. Nevertheless, its clinical use has been restrained because of its nephrotoxic potential. Royal jelly (RJ) and aliskiren (ALK) can individually prevent such toxic effects. The aim of this study was to explore the protective effects of a combination treatment of RJ and ALK on GM-mediated nephrotoxicity.

Materials and Methods

Thirty-two adult female. Wistar rats were divided equally into four groups: (I) Receiving normal saline; (II) GM (100 mg/kg, intraperitoneal [i.p.] injection); GM (100 mg/kg, i.p. injection) plus ALK (50 mg/kg, i.p. injection); and (IV) GM (100 mg/kg, i.p. injection) plus ALK (50 mg/kg, i.p. injection) in combination with RJ (150 mg/kg, orally). All treatments were administered daily for 10 days. The blood levels of creatinine, urea, uric acid, albumin, and total protein were measured. Then, the animals were sacrificed, and the kidneys were taken for histopathology.

Results

Compared to normal control rats, GM-injected rats showed significantly (p<0.001) higher serum concentrations of uric acid, urea, and creatinine as well as evidently (p<0.001) lower blood levels of albumin and total protein. Moreover, GM administration was associated with significant renal histopathological changes. All these alterations were considerably (p<0.05) improved in GM-injected rats receiving ALK compared to rats receiving GM alone. However, when RJ was given in combination with ALK to GM-injected rats, it lessened the beneficial nephroprotective effects of both agents.

Conclusion

The combination treatment of RJ and ALK is not desirable for GM-induced nephrotoxicity. Further studies are crucial to accurately explore the precise mechanism of RJ antagonistic interaction with ALK.

Functional and molecular evaluation of using aliskiren during acute and chronic partial ureteral obstruction in rat solitary kidney

AIMS

To study the effect of direct renin inhibitor (aliskiren) on the renal function during acute and chronic partial ureteral obstruction (PUO) in rat solitary kidney.

MAIN METHODS

Sixty male Sprague-Dawley rats were randomly allocated into three groups (20 rats each); sham, PUO and aliskiren groups. Right nephrectomy was performed in all groups. Rats in PUO and aliskiren groups were subjected to left PUO and received no treatment and aliskiren (10 mg/kg, orally, once per day till sacrification), respectively. Blood samples were then collected for biochemical measurements. Ten rats from each group were sacrificed after two weeks, while the remaining rats were sacrificed after four weeks. Left kidneys were harvested for histopathological examination, BCL-2, interleukin (IL)-6, transforming growth factor (TGF)-β1, collagen I and fibronectin relative gene expression and assessment of glutathione (GSH), superoxide dismutase (SOD), malondialdehyde (MDA) and nitric oxide (NO) activity.

KEY FINDINGS

After two and four weeks of PUO, aliskiren significantly recompensed the rise of serum creatinine (Scr) and blood urea nitrogen (BUN). Aliskiren also revealed significantly better histopathological results regarding cortical and medullary necrosis, regeneration and inflammatory cell infiltration. Aliskiren group showed statistically significant up-regulation of BCL-2 and down-regulation of IL-6, TGF-β1, collagen I and fibronectin relative gene expression. Aliskiren significantly increased GSH and SOD activity and reduced MDA and NO activity. Moreover, aliskiren administration for four weeks after PUO significantly yielded more renoprotective effect compared to its administration for two weeks.

SIGNIFICANCE

Aliskiren ameliorates the deterioration of the renal function during acute and chronic PUO in a solitary kidney.

The glucagon-like peptide-1 receptor agonist Exendin-4, ameliorates contrast-induced nephropathy through suppression of oxidative stress, vascular dysfunction and apoptosis independent of glycaemia

Contrast-induced nephropathy (CIN) is a leading cause of hospital-acquired acute kidney injury, particularly in diabetic patients. Previous studies have shown renoprotective effects of glucagon-like peptide-1 (GLP-1) signalling; however, its role in CIN remains unexplored. This study investigates the prophylactic effect of exendin-4, a GLP-1R agonist, against CIN in a rat model mimicking both healthy and diabetic conditions. Animals were randomly divided into 7 groups: a control sham group (n = 8), and 2 identical sets of 3 disease groups, one received exendin-4 before exposure to contrast medium (CM), while the other served as untreated control. The 3 disease groups represented diabetes (n = 8), CIN (n = 8), or diabetes and CIN combined (n = 8). Untreated groups showed deteriorating renal function as indicated by significantly higher levels of serum creatinine and blood urea nitrogen, malondialdehyde, and endothelin-1 and caspase-3 expression compared to the sham control group. This was accompanied by a significant decrease in tissue reserves of reduced glutathione, superoxide dismutase, nitrate and endothelin nitric oxide synthase as well as deteriorating renal histology. The CM-induced changes in diabetic rats indicate impaired renal function, oxidative stress, vascular dysfunction, and apoptosis, and were significance higher in intensity compared to non-diabetic rats. Pretreatment with exendin-4 ameliorated all the aforementioned CM-induced nephropathic effects independent of the glycemic state. To our knowledge, this is the first study describing the prophylactic renoprotective effects of exendin-4 against CIN. With the current pharmaceutical use of exendin-4 as a hypoglycaemic agent, the GLP-1R agonist becomes an interesting candidate for human clinical trials on CIN prevention.

Altered Circadian Timing System-Mediated Non-Dipping Pattern of Blood Pressure and Associated Cardiovascular Disorders in Metabolic and Kidney Diseases

The morning surge in blood pressure (BP) coincides with increased cardiovascular (CV) events. This strongly suggests that an altered circadian rhythm of BP plays a crucial role in the development of CV disease (CVD). A disrupted circadian rhythm of BP, such as the non-dipping type of hypertension (i.e., absence of nocturnal BP decline), is frequently observed in metabolic disorders and chronic kidney disease (CKD). The circadian timing system, controlled by the central clock in the suprachiasmatic nucleus of the hypothalamus and/or by peripheral clocks in the heart, vasculature, and kidneys, modulates the 24 h oscillation of BP. However, little information is available regarding the molecular and cellular mechanisms of an altered circadian timing system-mediated disrupted dipping pattern of BP in metabolic disorders and CKD that can lead to the development of CV events. A more thorough understanding of this pathogenesis could provide novel therapeutic strategies for the management of CVD. This short review will address our and others' recent findings on the molecular mechanisms that may affect the dipping pattern of BP in metabolic dysfunction and kidney disease and its association with CV disorders.

Lung Oxidative Stress, DNA Damage, Apoptosis, and Fibrosis in Adenine-Induced Chronic Kidney Disease in Mice

It is well-established that there is a crosstalk between the lung and the kidney, and several studies have reported association between chronic kidney disease (CKD) and pulmonary pathophysiological changes. Experimentally, CKD can be caused in mice by dietary intake of adenine. Nevertheless, the consequence of such intervention on the lung received only scant attention. Here, we assessed the pulmonary effects of adenine (0.2% w/w in feed for 4 weeks)-induced CKD in mice by assessing various physiological histological and biochemical endpoints. Adenine treatment induced a significant increase in urine output, urea and creatinine concentrations, and it decreased the body weight and creatinine clearance. It also increased proteinuria and the urinary levels of kidney injury molecule-1 and neutrophil gelatinase-associated lipocalin. Compared with control group, the histopathological evaluation of lungs from adenine-treated mice showed polymorphonuclear leukocytes infiltration in alveolar and bronchial walls, injury, and fibrosis. Moreover, adenine caused a significant increase in lung lipid peroxidation and reactive oxygen species and decreased the antioxidant catalase. Adenine also induced DNA damage assessed by COMET assay. Similarly, adenine caused apoptosis in the lung characterized by a significant increase of cleaved caspase-3. Moreover, adenine induced a significant increase in the expression of nuclear factor erythroid 2–related factor 2 (Nrf2) in the lung. We conclude that administration of adenine in mice induced CKD is accompanied by lung oxidative stress, DNA damage, apoptosis, and Nrf2 expression and fibrosis.