Glória Costa-Sarmento

The central aim of this study was to investigate whether male Wistar rats chronically fed a high-fat diet (HFD) over 106 days present high levels of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α), and Na⁺ and Ca²⁺ transport alterations in the left ventricle, together with dyslipidemia and decreased glucose tolerance, and to investigate the influence of Ang-(3–4). The rats became moderately overweight with an expansion of visceral adiposity. Na⁺-transporting ATPases, sarco-endoplasmic reticulum Ca²⁺-ATPase (SERCA2a), and the abundance of Angiotensin II receptors were studied together with lipid and glycemic profiles from plasma and left-ventricle echocardiographic parameters fractional shortening (FS) and ejection fraction (EF). IL-6 and TNF-α increased (62% and 53%, respectively), but returned to normal levels with Angiotensin-(3–4) administration after 106 days. Significant lipidogram alterations accompanied a decrease in glucose tolerance. Angiotensin II receptors abundance did not change. (Na⁺ + K⁺)ATPase and ouabain-resistant Na⁺-ATPase were downregulated and upregulated, respectively, but returned to normal values upon Angiotensin-(3–4) administration. SERCA2a lost its ability to respond to excess ATP. Echocardiography showed no changes in FS or EF. We conclude that being overweight causes an increase in Ang-(3–4)-sensitive IL-6 and TNF-α levels, and ion transport alterations in the left ventricle that could evolve into future heart dysfunction.

Overweight/obesity and cardiovascular diseases are associated with high rates of mobility and mortality. We investigated inflammatory lesions and ionic transporters in the left ventricle of male rats chronically fed a high-fat diet (HL). They developed moderate overweight with early expansion of visceral adiposity. The inflammatory markers interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-), Na+-transporting ATPases, sarco-endoplasmic reticulum Ca2+-ATPase (SERCA2a), and the abundance of Angiotensin II receptors were studied together with lipid and glycemic profiles, and the left ventricle echocardiographic parameters fractional shortening (FS) and ejection fraction (EF). HL rats doubled IL-6 and TNF-, which returned to normal levels when signaling coupled to Angiotensin II type 2 receptors (AT2R) was supraregulated by Ang-(3–4) administration. The decreased glucose tolerance was accompanied by significantly reduced plasma triglycerides due to intense hepatic steatosis (Crisóstomo et al. Metabolism Open. 2022, 14, 100176). AT2R (and AT1R) abundance did not change. (Na++K+)ATPase and ouabain-resistant Na+-ATPase were downregulated and upregulated, respectively, normalized with Ang-(3–4). SERCA2a lost its most critical regulatory property, inhibition by excess substrate. The ultrasound showed no changes in FS and EF. We conclude that very moderate overweight can cause silent initial molecular tissue damage in heart, which can evolve to cause systolic dysfunction.

The aim of the present study was to investigate whether chronic undernutrition modifies the response to rostafuroxin in juvenile rats. Chronic undernutrition was induced in male rats using a multideficient diet known as Regional Basic Diet (RBD), mimicking alimentary habits in impoverished regions worldwide. Animals were given RBD – or a control/CTRL normal diet for rodents – from weaning to 90 days, and rostafuroxin (1 mg/kg body mass) or vehicle were orally administered during the last 30 days. Undernourished rats became hypertensive at 55–60 days of age (tail-cuff recording). During the last two days, the rats were hosted in metabolic cages to measure food/energy, water, Na⁺ ingestion, and urinary volume. Blood and kidneys were collected after euthanasia. Rostafuroxin increased food/energy and Na⁺ intake in CTRL and RBD rats but had opposite effects on Na⁺ balance (intake minus urinary excretion): negative in CTRL and positive in RBD. The drug normalized the decreased plasma Na⁺ concentration found in RBD rats, increased urinary volume in RBD but not in CTRL, and decreased and increased urinary Na⁺ concentration in the RBD and CTRL groups, respectively. Rostafuroxin decreased the ouabain-sensitive (Na⁺+K⁺)ATPase and increased the ouabain-resistant, furosemide-sensitive Na⁺-ATPase from proximal tubule cells in both groups, and normalized the systolic blood pressure in RBD without effect in CTRL rats. We conclude that chronic undernutrition modifies the response of blood pressure, caloric metabolism, Na⁺ distribution in liquid compartments, mobilization of Na⁺ from non-osmotic compartments, Na⁺ and water balance, and activity of renal Na⁺-transporting ATPases to rostafuroxin.

Acute kidney injury (AKI) caused by ischemia followed by reperfusion (I/R) is characterized by intense anion superoxide (O₂^•−) production and oxidative damage. We investigated whether extracellular vesicles secreted by adipose tissue mesenchymal cells (EVs) administered during reperfusion can suppress the exacerbated mitochondrial O₂^•− formation after I/R. We used Wistar rats subjected to bilateral renal arterial clamping (30 min) followed by 24 h of reperfusion. The animals received EVs (I/R + EVs group) or saline (I/R group) in the kidney subcapsular space. The third group consisted of false-operated rats (SHAM). Mitochondria were isolated from proximal tubule cells and used immediately. Amplex Red™ was used to measure mitochondrial O₂^•− formation and MitoTracker™ Orange to evaluate inner mitochondrial membrane potential (Δψ). In vitro studies were carried out on human renal proximal tubular cells (HK-2) co-cultured or not with EVs under hypoxic conditions. Administration of EVs restored O₂^•− formation to SHAM levels in all mitochondrial functional conditions. The gene expression of catalase and superoxide dismutase-1 remained unmodified; transcription of heme oxygenase-1 (HO-1) was upregulated. The co-cultures of HK-2 cells with EVs revealed an intense decrease in apoptosis. We conclude that the mechanisms by which EVs favor long-term recovery of renal structures and functions after I/R rely on a decrease of mitochondrial O₂^•− formation with the aid of the upregulated antioxidant HO-1/Nuclear factor erythroid 2-related factor 2 system, thus opening new vistas for the treatment of AKI.

Acute kidney injury (AKI) caused by ischemia followed by reperfusion (I/R) is characterized by intense anion superoxide (O2•-) production and oxidative damage. We investigated whether extracellular vesicles secreted by adipose tissue mesenchymal cells (EVs) administrated during reperfusion can suppress the exacerbated mitochondrial O2•- formation after I/R. We used Wistar rats submitted to bilateral renal arterial clamping (30 min) followed by 24 h of reperfusion. The animals received EVs (I/R+EVs group) or saline, I/R group) in the kidney subcapsular space. The 3rd group was of the false-operated rats (SHAM). Mitochondria were isolated from proximal tubule cells and immediately used. Amplex Red™ was used to measure mitochondrial O2•- formation and MitoTracker® Orange to evaluate Δψ. In vitro studies were carried out by using human renal proximal tubular cells (HK-2) co-cultured or not with EVs under hypoxia conditions. Administration of EVs restored O2•- formation to SHAM levels in all mitochondrial functional conditions. The expression of catalase and superoxide dismutase remained unmodified; transcription of heme oxygenase-1 (HO-1) was upregulated. The co-cultures of HK-2 cells with EVs revealed an intense decrease in apoptosis. We conclude that the mechanisms by which EVs recover the renal structure and function after I/R are related to the normalization of the mitochondrial redox environment. The intravesicular catalase is central in the preservation mechanisms that, with the aid of the upregulated antioxidant HO-1/Nuclear factor erythroid 2-related factor 2 system, depress early processes of cell death after I/R and open new vistas for the treatment of AKI.