Recombinant Cellular Repressor of E1A-Stimulated Genes Protects against Renal Fibrosis in Dahl Salt-Sensitive Rats.

BACKGROUND: Human cellular repressor of E1A-stimulated genes (CREG) is a secreted glycoprotein that attenuates angiotensin II-induced hypertension, alleviates myocardial fibrosis, and improves heart function. However, the role of CREG in high-salt (HS) diet-induced hypertensive nephropathy is unclear. METHODS: To determine the effects and molecular mechanisms of CREG in HS diet-induced hypertensive nephropathy, we established a hypertensive nephropathy animal model in Dahl salt-sensitive (SS) rats fed a HS diet (8% NaCl, n = 20) for 8 weeks. At week 4 of HS loading, these rats were administered recombinant CREG (reCREG; 35 µg/kg·day, n = 5) and saline (n = 5) via subcutaneously implanted pumps and were also administered the vasodilator hydralazine (20 mg/kg·day, n = 5) in drinking water. We used hematoxylin and eosin staining, Masson's trichrome staining, immunohistochemical labeling, western blotting, RT-PCR, and Tunel staining to determine the signaling pathways of CREG in HS diet-induced hypertensive nephropathy. RESULTS: After 8 weeks of HS intake, the Dahl SS rats developed renal dysfunction and severe renal fibrosis associated with reductions of 78 and 67% in CREG expression, respectively, at both mRNA and protein levels in the kidney. Administration of reCREG improved renal function and relieved renal fibrosis. Administration of CREG also inhibited monocyte infiltration and reduced apoptosis in the kidney cells. CREG overexpression upregulated forkhead box P1 expression and inhibited the transforming growth factor-ß1 signaling pathway. CONCLUSION: Our study shows that CREG protected the kidney against HS-diet-induced renal damage and provides new insights into the mechanisms underlying kidney injury.

CREG1 ameliorates myocardial fibrosis associated with autophagy activation and Rab7 expression.

In cardiomyocytes subjected to stress, autophagy activation is a critical survival mechanism that preserves cellular energy status while degrading damaged proteins and organelles. However, little is known about the mechanisms that govern this autophagic response. Cellular repressor of E1A genes (CREG1) is an evolutionarily conserved lysosomal protein, and an important new factor in regulating tissues homeostasis that has been shown to antagonize injury of tissues or cells. In the present study, we aimed to investigate the regulatory role of CREG1 in cardiac autophagy, and to clarify autophagy activation mechanisms. First, we generated a CREG1 haploinsufficiency (Creg1(+/-)) mouse model, and identified that CREG1 deficiency aggravates myocardial fibrosis in response to aging or angiotensin II (Ang II). Conversely, exogenous infusion of recombinant CREG1 protein complete reversed cardiac damage. CERG1 deficiency in Creg1(+/-) mouse heart showed a market accumulation of autophagosome that acquired LC3II and beclin-1, and a decrease in autophagic flux clearance as indicated by upregulating the level of p62. Inversely, restoration of CREG1 activates cardiac autophagy, Furthermore, chloroquine, an inhibitor of lysosomal acidification, was used to confirm that CREG1 protected the heart tissue against Ang II-induced fibrosis by activating autophagy. Using adenoviral infection of primary cardiomyocytes, overexpression of CREG1 with concurrent resveratrol treatment significantly increased autophagy, while silencing CREG1 blocked the resveratrol-induced autophagy. These results suggest that CREG1-induced autophagy is required to maintain heart function in the face of stress-induced myocardiac damage. Both in vitro and in vivo studies identified that CREG1 deficiency influenced the maturation of lysosomes and reduced the espression of Rab7, which might be involved in CREG1-induced cardiomyocyte autophagy. These findings suggest that autophagy activation via CREG1 may be a viable therapeutic strategy autophagy for improving cardiac performance under pathologic conditions. This article is part of a Special Issue entitled: autophagy and protein quality control in cardiometabolic diseases.

Circulating Soluble ST2 Predicts All-Cause Mortality in Severe Heart Failure Patients with an Implantable Cardioverter Defibrillator.

BACKGROUND: Heart failure (HF) is the terminal stage of all cardiovascular events. Although implantable cardioverter defibrillator (ICD) therapies have reduced mortality among the high-risk HF population, it is necessary to determine whether certain factors can predict mortality even after cardiac device implantation. Growth stimulation expressed gene 2 (ST2) is an emerging biomarker for HF patient stratification in different clinical settings. AIMS: This study aimed to investigate the relationship between baseline soluble ST2 (sST2) levels in serum and the clinical outcomes of high-risk HF patients with device implantation. METHODS: Between January 2017 and August 2018, we prospectively recruited consecutive patients implanted with an ICD for heart failure, with LVEF ≤35% as recommended, and analyzed the basic characteristics, baseline serum sST2, and NT-proBNP levels, with at least 1-year follow-up. All-cause mortality was the primary endpoint. RESULTS: During a 643-day follow-up, all-cause mortality occurred in 16 of 150 patients (10.67%). Incidence of all-cause mortality increased significantly in patients with sST2 levels above 34.98846 ng/ml (16.00% vs. 5.33%, P = 0.034). After adjusting the model (age, gender, device implantation, prevention of sudden death, LVEDD, LVEF, WBC and CLBBB, hsTNT, etiology, and eGFR) and the model combined with NT-proBNP, the risk of all-cause death was increased by 2.5% and 1.9%, respectively, per ng/ml of sST2. The best sST2 cutoff for predicting all-cause death was 43.42671 ng/ml (area under the curve: 0.72, sensitive: 0.69, and specificity: 0.69). Compared to patients with sST2 levels below 43.42671 ng/ml, the risk of all-cause mortality was higher in those with values above the threshold (5.1% vs. 21.2%, P = 0.002). ST2 level ≥43.42671 ng/ml was an independent predictor of all-cause mortality (HR: 3.30 [95% CI 1.02-10.67]). Age (HR: 1.06 [95% CI: 1.01-1.12]) and increased NT-proBNP per 100 (HR: 1.02 [95% CI: 1.01-1.03]) were also associated with all-cause mortality in ICD patients. CONCLUSIONS: sST2 level was associated with risk of all-cause mortality, and a threshold of 43.43 ng/ml showed good distinguishing performance to predict all-cause mortality in patients with severe heart failure, recommended for ICD implantation. Patients with sST2 levels more than 43.42671 ng/ml even after ICD implantation should therefore be monitored carefully.