Canagliflozin mitigates ferroptosis and ameliorates heart failure in rats with preserved ejection fraction.

Recently, hypoglycemic drugs belonging to sodium-glucose cotransporter 2 inhibitors (SGLT2i) have generated significant interest due to their clear cardiovascular benefits for heart failure with preserved ejection fraction (HFpEF) since there are no effective drugs that may improve clinical outcomes for these patients over a prolonged period. But, the underlying mechanisms remain unclear, particularly its effects on ferroptosis, a newly defined mechanism of iron-dependent non-apoptotic cell death during heart failure (HF). Here, with proteomics, we demonstrated that ferroptosis might be a key mechanism in a rat model of high-salt diet-induced HFpEF, characterized by iron overloading and lipid peroxidation, which was blocked following treatment with canagliflozin. Data are available via ProteomeXchange with identifier PXD029031. The ferroptosis was evaluated with the levels of acyl-CoA synthetase long-chain family member 4, glutathione peroxidase 4, ferritin heavy chain 1, transferrin receptor, Ferroportin 1, iron, glutathione, malondialdehyde, and 4-hydroxy-trans-2-nonenal. These findings highlight the fact that targeting ferroptosis may serve as a cardioprotective strategy for HFpEF prevention and suggest that canagliflozin may exert its cardiovascular benefits partly via its mitigation of ferroptosis.

Corticosteroids significantly increase cystatin C levels in the plasma by promoting cystatin C production in rats.

Background: Several studies have shown that non-renal factors such as corticosteroids may increase plasma cystatin C levels without affecting kidney function. However, the mechanisms underlying this are unclear. We hypothesized that corticosteroids may increase cystatin C levels in the plasma by promoting its production in tissues. In the present study, we aimed to test our hypothesis in rats by investigating the effect of corticosteroids on cystatin C production in tissues and the glomerular filtration rate (GFR), as measured by the gold standard method (i.e., inulin clearance). Results: Dexamethasone treatment was associated with much higher concentrations of cystatin C in all organ tissue homogenates tested. Dexamethasone increased plasma cystatin C levels in rats, without any decrease in renal inulin clearance. The impact of dexamethasone on plasma and organ tissue cystatin C levels was abolished by RU486, indicating the effect was glucocorticoid receptor-mediated. Conclusions: Our study provides direct evidence that corticosteroids may increase cystatin C levels in the plasma by promoting its production, without any decrease in GFR.

Dexamethasone-induced diuresis is associated with inhibition of the renin-angiotensin-aldosterone system in rats.

In heart failure (HF) patients, diuretics remain the cornerstone of therapy to relieve fluid retention. However, the resulting volume loss activates the renin-angiotensin-aldosterone system (RAAS), which blunts the decline in volume depletion and blood pressure. RAAS activation, in turn, compromises the diuretic decongesting effect. Although corticosteroids can induce potent diuresis in HF patients, the effects of corticosteroids on RAAS activation remain unclear. Therefore, we assessed the effects of dexamethasone (Dex) on urine output and plasma angiotensin II and aldosterone levels in rats following water deprivation-induced dehydration, following induction of chronic HF (CHF), and following induction of CHF and volume expansion therapy. In the dehydration model, Dex significantly increased urine output and inhibited dehydration-induced RAAS activation. This favorable effect was abolished by the glucocorticoid receptor antagonist RU486, suggesting involvement of the glucocorticoid receptor. In the CHF model, Dex treatments doubled urine output without activating RAAS. Moreover, in acute volume expansion experiments, Dex pretreatments led to potent diuresis during the pretreatment period and restored renal adaptation to acute volume expansion without activating RAAS in rats with CHF. Collectively, these data show that corticosteroids induce potent diuresis without activating RAAS in rats.

Prednisone lowers serum uric acid levels in patients with decompensated heart failure by increasing renal uric acid clearance.

Clinical studies have shown that large doses of prednisone could lower serum uric acid (SUA) in patients with decompensated heart failure (HF); however, the optimal dose of prednisone and underlying mechanisms are unknown. Thirty-eight patients with decompensated HF were randomized to receive standard HF care alone (n = 10) or with low-dose (15 mg/day, n = 8), medium-dose (30 mg/day, n = 10), or high-dose prednisone (60 mg/day, n = 10), for 10 days. At the end of the study, only high-dose prednisone significantly reduced SUA, whereas low- and medium-dose prednisone and standard HF care had no effect on SUA. The reduction in SUA in high-dose prednisone groups was associated with a significant increase in renal uric acid clearance. In conclusion, prednisone can reduce SUA levels by increasing renal uric acid clearance in patients with decompensated HF.

Corticosteroids Significantly Increase Serum Cystatin C Concentration without Affecting Renal Function in Symptomatic Heart Failure.

BACKGROUND: Human cystatin C is a single non-glycosylated polypeptide chain consisting of 120 amino acid residues. Its concentration in the circulation is mainly determined by glomerular filtration rate. However, non-renal factors, i.e., drugs, may dramatically affect its levels in the circulation. The aim of this study was to evaluate the effect of corticosteroid treatment on serum cystatin C concentration in patients with symptomatic heart failure. METHODS: Fifty-six symptomatic heart failure patients were treated with prednisone. Concentrations of serum cystatin C and serum creatinine were recorded at baseline, and after about 2 weeks of treatment. Twenty-four hour urinary creatinine was also measured to directly calculate glomerular filtration rate. RESULTS: Prednisone treatment significantly increased serum cystatin C concentration from 1.24 +/- 0.40 mg/L at baseline to 1.61 +/- 0.80 mg/L at the end of study (p < 0.05). However, the elevation in serum cystatin C concentration was not associated with renal function impairment. Prednisone not only significantly decreased serum creatinine concentrations from 89.66 +/- 28.63 pmol/L at baseline to 76.55 +/- 20.80 micromol/L after prednisone treatment (p < 0.05), but also significantly increased fractional excretion of sodium and urine flow rate. The data also showed there was a slight and but nonstatistically significant increase in glomerular filtration rate in such patients after prednisone treatment. CONCLUSIONS: Important non-renal factors, such as corticosteroids, can influence cystatin C concentration. Thus, it needs to be considered when interpreting cystatin C values in patients with heart failure receiving corticosteroid therapy.