Design and baseline characteristics of the Finerenone, in addition to standard of care, on the progression of kidney disease in patients with Non-Diabetic Chronic Kidney Disease (FIND-CKD) randomized trial.

BACKGROUND AND HYPOTHESIS: Finerenone, a non-steroidal mineralocorticoid receptor antagonist, improved kidney, and cardiovascular outcomes in patients with CKD and T2D in two Phase 3 outcome trials. The FIND-CKD study investigates the effect of finerenone in adults with CKD without diabetes. METHODS: FIND-CKD (NCT05047263 and EU CT 2023-506897-11-00) is a randomized, double-blind, placebo-controlled Phase 3 trial in patients with CKD of non-diabetic aetiology. Adults with a urinary albumin-creatinine ratio (UACR) of ≥ 200 to ≤3500 mg/g and eGFR ≥ 25 to <90 mL/min/1.73 m2 receiving a maximum tolerated dose of a renin-angiotensin-system (RAS) inhibitor were randomized 1:1 to once daily placebo or finerenone 10 or 20 mg depending on eGFR above or below 60 mL/min/1.73 m2. The primary efficacy outcome is total eGFR slope, defined as the mean annual rate of change in eGFR from baseline to Month 32. Secondary efficacy outcomes include a combined cardiorenal composite outcome comprising time to kidney failure, sustained ≥57% decrease in eGFR, hospitalization for heart failure, or cardiovascular death, as well as separate kidney and cardiovascular composite outcomes. Adverse events are recorded to assess tolerability and safety. RESULTS: Across 24 countries, 3231 patients were screened and 1584 were randomized to study treatment. The most common causes of CKD were chronic glomerulonephritis (57.0%) and hypertensive/ischaemic nephropathy (29.0%). Immunoglobulin A nephropathy was the most common glomerulonephritis (26.3% of the total population). At baseline, mean eGFR and median UACR were 46.7 mL/min/1.73 m2 and 818.9 mg/g, respectively. Diuretics were used by 282 participants (17.8%), statins by 851 (53.7%), and calcium channel blockers by 794 (50.1%). SGLT2 inhibitors were used in 16.9% of patients; these individuals had a similar mean eGFR (45.6 vs 46.8 mL/min/1.73 m2) and slightly higher median UACR (871.9 vs 808.3 mg/g) compared to those not using SGLT2 inhibitors at baseline. CONCLUSIONS: FIND-CKD is the first Phase 3 trial of finerenone in patients with CKD of non-diabetic aetiology.

Lack of Gαi2 leads to dilative cardiomyopathy and increased mortality in ß1-adrenoceptor overexpressing mice.

AIMS: Inhibitory G (Gi) proteins have been proposed to be cardioprotective. We investigated effects of Gαi2 knockout on cardiac function and survival in a murine heart failure model of cardiac ß1-adrenoceptor overexpression. METHODS AND RESULTS: ß1-transgenic mice lacking Gαi2 (ß1-tg/Gαi2 (-/-)) were compared with wild-type mice and littermates either overexpressing cardiac ß1-adrenoceptors (ß1-tg) or lacking Gαi2 (Gαi2 (-/-)). At 300 days, mortality of mice only lacking Gαi2 was already higher compared with wild-type or ß1-tg, but similar to ß1-tg/Gαi2 (-/-), mice. Beyond 300 days, mortality of ß1-tg/Gαi2 (-/-) mice was enhanced compared with all other genotypes (mean survival time: 363 ± 21 days). At 300 days of age, echocardiography revealed similar cardiac function of wild-type, ß1-tg, and Gαi2 (-/-) mice, but significant impairment for ß1-tg/Gαi2 (-/-) mice (e.g. ejection fraction 14 ± 2 vs. 40 ± 4% in wild-type mice). Significantly increased ventricle-to-body weight ratio (0.71 ± 0.06 vs. 0.48 ± 0.02% in wild-type mice), left ventricular size (length 0.82 ± 0.04 vs. 0.66 ± 0.03 cm in wild types), and atrial natriuretic peptide and brain natriuretic peptide expression (mRNA: 2819 and 495% of wild-type mice, respectively) indicated hypertrophy. Gαi3 was significantly up-regulated in Gαi2 knockout mice (protein compared with wild type: 340 ± 90% in Gαi2 (-/-) and 394 ± 80% in ß1-tg/Gαi2 (-/-), respectively). CONCLUSIONS: Gαi2 deficiency combined with cardiac ß1-adrenoceptor overexpression strongly impaired survival and cardiac function. At 300 days of age, ß1-adrenoceptor overexpression alone had not induced cardiac hypertrophy or dysfunction while there was overt cardiomyopathy in mice additionally lacking Gαi2. We propose an enhanced effect of increased ß1-adrenergic drive by the lack of protection via Gαi2. Gαi3 up-regulation was not sufficient to compensate for Gαi2 deficiency, suggesting an isoform-specific or a concentration-dependent mechanism.

Effect of MANT-nucleotides on L-type calcium currents in murine cardiomyocytes.

Membranous adenylyl cyclases play a major role in G-protein-coupled receptor signalling and regulate various cellular responses, such as cardiac contraction. Cardiac apoptosis and development of cardiac dysfunction is prevented in mice lacking AC 5, a predominant isoform in the heart. In the search for a potent and selective AC 5 inhibitor, we recently identified 2'(3')-methylanthraniloyl-inosine-5'-triphosphate(MANT-ITP) as the most potent AC 5 inhibitor with a K ( i ) of 13 nM. Therefore, AC inhibition of MANT-ITP was assessed in ventricular cardiomyocytes and compared to three other MANT-nucleotides to evaluate its effect on cardiac signalling. Basal and isoproterenol-induced L-type calcium currents (I (Ca,L)) in murine ventricular cardiomyocytes were recorded by whole-cell patch-clamp technique, using four different MANT-nucleotides. The effects of the MANT-nucleotides on I (Ca,L) were unexpectedly complex. All MANT-nucleotides exhibited an inhibitory effect on basal I (Ca,L). Additionally, several MANT-nucleotides, i.e., MANT-ITPγS, MANT-ATP, and MANT-ITP, caused a strong initial increase in basal I (Ca,L) within the first 2.5 min that appeared to be unrelated to AC 5 inhibition. However, we detected a significant reduction on isoproterenol-induced I (Ca,L) with MANT-ITP, supporting the notion that AC 5 plays an important role in agonist-stimulated activation of I (Ca,L). Collectively, MANT-nucleotides are useful tools for the characterization of recombinant ACs, for fluorescence studies and crystallography, but in intact cardiomyocytes, caution must be exerted since MANT-nucleotides apparently possess additional effects than AC 5 inhibition, limiting their usefulness as tools for intact cell studies.

Gαi2- and Gαi3-specific regulation of voltage-dependent L-type calcium channels in cardiomyocytes.

BACKGROUND: Two pertussis toxin sensitive G(i) proteins, G(i2) and G(i3), are expressed in cardiomyocytes and upregulated in heart failure. It has been proposed that the highly homologous G(i) isoforms are functionally distinct. To test for isoform-specific functions of G(i) proteins, we examined their role in the regulation of cardiac L-type voltage-dependent calcium channels (L-VDCC). METHODS: Ventricular tissues and isolated myocytes were obtained from mice with targeted deletion of either Gα(i2) (Gα(i2) (-/-)) or Gα(i3) (Gα(i3) (-/-)). mRNA levels of Gα(i/o) isoforms and L-VDCC subunits were quantified by real-time PCR. Gα(i) and Ca(v)α(1) protein levels as well as protein kinase B/Akt and extracellular signal-regulated kinases 1/2 (ERK1/2) phosphorylation levels were assessed by immunoblot analysis. L-VDCC function was assessed by whole-cell and single-channel current recordings. RESULTS: In cardiac tissue from Gα(i2) (-/-) mice, Gα(i3) mRNA and protein expression was upregulated to 187 ± 21% and 567 ± 59%, respectively. In Gα(i3) (-/-) mouse hearts, Gα(i2) mRNA (127 ± 5%) and protein (131 ± 10%) levels were slightly enhanced. Interestingly, L-VDCC current density in cardiomyocytes from Gα(i2) (-/-) mice was lowered (-7.9 ± 0.6 pA/pF, n = 11, p<0.05) compared to wild-type cells (-10.7 ± 0.5 pA/pF, n = 22), whereas it was increased in myocytes from Gα(i3) (-/-) mice (-14.3 ± 0.8 pA/pF, n = 14, p<0.05). Steady-state inactivation was shifted to negative potentials, and recovery kinetics slowed in the absence of Gα(i2) (but not of Gα(i3)) and following treatment with pertussis toxin in Gα(i3) (-/-). The pore forming Ca(v)α(1) protein level was unchanged in all mouse models analyzed, similar to mRNA levels of Ca(v)α(1) and Ca(v)ß(2) subunits. Interestingly, at the cellular signalling level, phosphorylation assays revealed abolished carbachol-triggered activation of ERK1/2 in mice lacking Gα(i2). CONCLUSION: Our data provide novel evidence for an isoform-specific modulation of L-VDCC by Gα(i) proteins. In particular, loss of Gα(i2) is reflected by alterations in channel kinetics and likely involves an impairment of the ERK1/2 signalling pathway.