Beneficial Effects of Mineralocorticoid Receptor Pathway Blockade against Endothelial Inflammation Induced by SARS-CoV-2 Spike Protein.

BACKGROUND: Vascular endothelial cells activation and dysfunction mediate inflammation and abnormal coagulation in COVID-19 patients. Mineralocorticoid receptor (MR) signaling and its downstream target Galectin-3 (Gal-3) are known to mediate cardiovascular inflammation and might be involved in the pathogenesis of COVID-19 complications. Accordingly, we aimed to investigate the potential beneficial effects of MR antagonism and Gal-3 inhibition on the inflammatory response induced by SARS-CoV-2 Spike protein in human aortic endothelial cells (HAECs). METHODS: HAECs were treated with recombinant SARS-COV2 Spike (S) protein. MR antagonists (namely spironolactone and eplerenone) or the Gal-3 inhibitor G3P-01 were supplemented before and after S protein challenge. HAECs supernatants were assessed by ELISA or Western blotting. RESULTS: HAECs treated with recombinant S protein resulted in enhanced secretion of inflammatory molecules (interleukin-6, monocyte chemoattractant protein-1, interleukin-18, interleukin-27, and interferon-γ) as well as in the thrombosis marker plasminogen activator inhibitor (PAI)-1. This was prevented and reversed by both MR antagonists and G3P-01. CONCLUSIONS: These findings indicate that MR/Gal-3 pathway blockade could be a promising option to reduce endothelial inflammation in SARS-CoV-2 infection.

Antifibrotic effect of novel neutrophil gelatinase-associated lipocalin inhibitors in cardiac and renal disease models.

Neutrophil gelatinase-associated lipocalin (NGAL) is involved in cardiovascular and renal diseases. Gene inactivation of NGAL blunts the pathophysiological consequences of cardiovascular and renal damage. We aimed to design chemical NGAL inhibitors and investigate its effects in experimental models of myocardial infarction (MI) and chronic kidney disease induced by 5/6 nephrectomy (CKD) on respectively 8-12 weeks old C57Bl6/j and FVB/N male mice. Among the 32 NGAL inhibitors tested, GPZ614741 and GPZ058225 fully blocked NGAL-induced inflammatory and profibrotic markers in human cardiac fibroblasts and primary mouse kidney fibroblasts. The administration of GPZ614741 (100 mg/kg/day) for three months, was able to improve cardiac function in MI mice and reduced myocardial fibrosis and inflammation. The administration of GPZ614741 (100 mg/kg/day) for two months resulting to no renal function improvement but prevented the increase in blood pressure, renal tubulointerstitial fibrosis and profibrotic marker expression in CKD mice. In conclusion, we have identified new compounds with potent inhibitory activity on NGAL-profibrotic and pro-inflammatory effects. GPZ614741 prevented interstitial fibrosis and dysfunction associated with MI, as well as tubulointerstitial fibrosis in a CKD model. These inhibitors could be used for other diseases that involve NGAL, such as cancer or metabolic diseases, creating new therapeutic options.

The Mineralocorticoid Receptor Antagonist Eplerenone Suppresses Interstitial Fibrosis in Subcutaneous Adipose Tissue in Patients With Type 2 Diabetes.

Activation of the mineralocorticoid receptor (MR) may promote dysfunctional adipose tissue in patients with type 2 diabetes, where increased pericellular fibrosis has emerged as a major contributor. The knowledge of the association among the MR, fibrosis, and the effects of an MR antagonist (MRA) in human adipocytes remains very limited. The present substudy, including 30 participants, was prespecified as part of the Mineralocorticoid Receptor Antagonist in Type 2 Diabetes (MIRAD) trial, which randomized patients to either high-dose eplerenone or placebo for 26 weeks. In adipose tissue biopsies, changes in fibrosis were evaluated by immunohistological examination and by the expression of mRNA and protein markers of fibrosis. Treatment with an MRA reduced pericellular fibrosis, synthesis of the major subunits of collagen types I and VI, and the profibrotic factor α-smooth muscle actin compared with placebo in subcutaneous adipose tissue. Furthermore, we found decreased expression of the MR and downstream molecules neutrophil gelatinase-associated lipocalin, galectin-3, and lipocalin-like prostaglandin D2 synthase with an MRA. In conclusion, we present original data demonstrating reduced fibrosis in adipose tissue with inhibition of the MR, which could be a potential therapeutic approach to prevent the extracellular matrix remodeling of adipose tissue in type 2 diabetes.

Myocardial Injury After Ischemia/Reperfusion Is Attenuated By Pharmacological Galectin-3 Inhibition.

Although optimal therapy for myocardial infarction includes reperfusion to restore blood flow to the ischemic region, ischemia/reperfusion (IR) also initiates an inflammatory response likely contributing to adverse left ventricular (LV) extracellular matrix (ECM) remodeling. Galectin-3 (Gal-3), a ß-galactoside-binding-lectin, promotes cardiac remodeling and dysfunction. Our aim is to investigate whether Gal-3 pharmacological inhibition using modified citrus pectin (MCP) improves cardiac remodeling and functional changes associated with IR. Wistar rats were treated with MCP from 1 day before until 8 days after IR (coronary artery ligation) injury. Invasive hemodynamics revealed that both LV contractility and LV compliance were impaired in IR rats. LV compliance was improved by MCP treatment 8 days after IR. Cardiac magnetic resonance imaging showed decreased LV perfusion in IR rats, which was improved with MCP. There was no difference in LV hypertrophy in MCP-treated compared to untreated IR rats. However, MCP treatment decreased the ischemic area as well as Gal-3 expression. Gal-3 blockade paralleled lower myocardial inflammation and reduced fibrosis. These novel data showing the benefits of MCP in compliance and ECM remodeling in IR reinforces previously published data showing the therapeutic potential of Gal-3 inhibition.

Galectin-3 pharmacological inhibition attenuates early renal damage in spontaneously hypertensive rats.

BACKGROUND: The pharmacological blockade of galectin-3 (Gal-3), a ß-galactoside-binding lectin, reduces renal impairment in acute kidney injury, hyperaldosteronism or nephropathy. We herein investigated the effects of pharmacological Gal-3 inhibition by modified citrus pectin (MCP) in renal damage in spontaneously hypertensive rats (SHRs). METHODS AND RESULTS: Gal-3 inhibition did not modify blood pressure levels in 30-week-old SHR. Kidney weight was higher in SHR, with no effect of MCP treatment (100 mg/kg/day in the drinking water). Plasma creatinine and albuminuria were slightly but significantly increased in SHR and reduced by MCP, as well as plasma and urinary neutrophil gelatinase-associated lipocalin. In kidney from SHR, Gal-3 was upregulated, as well as the fibrotic markers (collagen type I, TGF-ß and connective tissue growth factor) and tubulointerstitial fibrosis. MCP treatment reduced Gal-3 levels and fibrosis. The epithelial-mesenchymal transition (EMT) molecules (fibronectin, α-smooth muscle actin and ß-catenin) were modified in SHR and normalized by Gal-3 inhibition. The inflammatory mediators (monocyte chemoattractant protein-1, osteopontin, cd68, cd80, cd44 and cd45) were elevated in SHR and attenuated by MCP. Renal damage markers (neutrophil gelatinase-associated lipocalin and kidney injury molecule-1) were augmented in SHR and improved by MCP. In renal epithelial normal rat kidney-52E cells, Gal-3 treatment induced EMT markers, whereas Gal-3 silencing attenuated EMT. CONCLUSION: Gal-3 inhibition attenuated early renal damage in SHR as indicated by reduced albuminuria, improved renal function and decreased renal fibrosis, EMT and inflammation, independently of blood pressure levels. These data suggest that Gal-3 could be a potential therapeutic candidate for the prevention of early renal alterations in hypertension.

Beneficial Effects of Galectin-3 Blockade in Vascular and Aortic Valve Alterations in an Experimental Pressure Overload Model.

Galectin-3 (Gal-3) is involved in cardiovascular fibrosis and aortic valve (AV) calcification. We hypothesized that Gal-3 pharmacological inhibition with modified citrus pectin (MCP) could reduce aortic and AV remodeling in normotensive rats with pressure overload (PO). Six weeks after aortic constriction, vascular Gal-3 expression was up-regulated in male Wistar rats. Gal-3 overexpression was accompanied by an increase in the aortic media layer thickness, enhanced total collagen, and augmented expression of fibrotic mediators. Further, vascular inflammatory markers as well as inflammatory cells content were greater in aorta from PO rats. MCP treatment (100 mg/kg/day) prevented the increase in Gal-3, media thickness, fibrosis, and inflammation in the aorta of PO rats. Gal-3 levels were higher in AVs from PO rats. This paralleled enhanced AV fibrosis, inflammation, as well as greater expression of calcification markers. MCP treatment prevented the increase in Gal-3 as well as fibrosis, inflammation, and calcification in AVs. Overall, Gal-3 is overexpressed in aorta and AVs from PO rats. Gal-3 pharmacological inhibition blocks aortic and AV remodeling in experimental PO. Gal-3 could be a new therapeutic approach to delay the progression and the development of aortic remodeling and AV calcification in PO.

Role for Galectin-3 in Calcific Aortic Valve Stenosis.

BACKGROUND: Aortic stenosis (AS) is a chronic inflammatory disease, and calcification plays an important role in the progression of the disease. Galectin-3 (Gal-3) is a proinflammatory molecule involved in vascular osteogenesis in atherosclerosis. Therefore, we hypothesized that Gal-3 could mediate valve calcification in AS. METHODS AND RESULTS: Blood samples and aortic valves (AVs) from 77 patients undergoing AV replacement were analyzed. As controls, noncalcified human AVs were obtained at autopsy (n=11). Gal-3 was spontaneously expressed in valvular interstitial cells (VICs) from AVs and increased in AS as compared to control AVs. Positive correlations were found between circulating and valvular Gal-3 levels. Valvular Gal-3 colocalized with the VICs markers, alpha-smooth muscle actin and vimentin, and with the osteogenic markers, osteopontin, bone morphogenetic protein 2, runt-related transcription factor 2, and SRY (sex-determining region Y)-box 9. Gal-3 also colocalized with the inflammatory markers cd68, cd80 and tumor necrosis factor alpha. In vitro, in VICs isolated from AVs, Gal-3 induced expression of inflammatory, fibrotic, and osteogenic markers through the extracellular signal-regulated kinase 1 and 2 pathway. Gal-3 expression was blocked in VICs undergoing osteoblastic differentiation using its pharmacological inhibitor, modified citrus pectin, or the clustered regularly interspaced short palindromic repeats/Cas9 knockout system. Gal-3 blockade and knockdown decreased the expression of inflammatory, fibrotic, and osteogenic markers in differentiated VICs. CONCLUSIONS: Gal-3, which is overexpressed in AVs from AS patients, appears to play a central role in calcification in AS. Gal-3 could be a new therapeutic approach to delay the progression of AV calcification in AS.

Galectin-3 Blockade Reduces Renal Fibrosis in Two Normotensive Experimental Models of Renal Damage.

BACKGROUND: Galectin-3 (Gal-3), a ß-galactoside-binding lectin, is increased in kidney injury and its pharmacological blockade reduces renal damage in acute kidney injury, hyperaldosteronism or hypertensive nephropathy. We herein investigated the effects of pharmacological Gal-3 inhibition by modified citrus pectin (MCP) in early renal damage associated with obesity and aortic stenosis (AS). RESULTS: Gal-3 was upregulated in kidneys from high fat diet (HFD) rats and in animals with partial occlusion of ascending aorta (AS). Urinary and plasma neutrophil gelatinase-associated lipocalin (NGAL) and urinary albumin were enhanced in HFD and AS rats. In kidney from obese rats, fibrotic markers (collagen, TFG-ß), epithelial-mesenchymal transition molecules (α-smooth muscle actin, E-cadherin), inflammatory mediator (osteopontin) and kidney injury marker (kidney injury molecule-1) were modified. In kidney from AS rats, fibrotic markers (collagen, CTGF), epithelial-mesenchymal transition molecules (fibronectin, α-smooth muscle actin, ß-catenin, E-cadherin) and kidney injury markers (NGAL, kidney injury molecule-1) were altered. Histologic observations of obese and AS rat kidneys revealed tubulointerstitial fibrosis. The pharmacological inhibition of Gal-3 with MCP normalized renal Gal-3 levels as well as functional, histological and molecular alterations in obese and AS rats. CONCLUSIONS: In experimental models of mild kidney damage, the increase in renal Gal-3 expression paralleled with renal fibrosis, inflammation and damage, while these alterations were prevented by Gal-3 blockade. These data suggest that Gal-3 could be a new player in renal molecular, histological and functional alterations at early stages of kidney damage.

Galectin-3 Participates in Cardiovascular Remodeling Associated With Obesity.

Remodeling, diastolic dysfunction, and arterial stiffness are some of the alterations through which obesity affects the cardiovascular system. Fibrosis and inflammation are important mechanisms underlying cardiovascular remodeling, although the precise promoters involved in these processes are still unclear. Galectin-3 (Gal-3) induces inflammation and fibrosis in the cardiovascular system. We have investigated the potential role of Gal-3 in cardiac damage in morbidly obese patients, and we have evaluated the protective effect of the Gal-3 inhibition in the occurrence of cardiovascular fibrosis and inflammation in an experimental model of obesity. Morbid obesity is associated with alterations in cardiac remodeling, mainly left ventricular hypertrophy and diastolic dysfunction. Obesity and hypertension are the main determinants of left ventricular hypertrophy. Insulin resistance, left ventricular hypertrophy, and circulating levels of C-reactive protein and Gal-3 are associated with a worsening of diastolic function in morbidly obese patients. Obesity upregulates Gal-3 production in the cardiovascular system in a normotensive animal model of diet-induced obesity by feeding for 6 weeks a high-fat diet (33.5% fat). Gal-3 inhibition with modified citrus pectin (100 mg/kg per day) reduced cardiovascular levels of Gal-3, total collagen, collagen I, transforming and connective growth factors, osteopontin, and monocyte chemoattractant protein-1 in the heart and aorta of obese animals without changes in body weight or blood pressure. In morbidly obese patients, Gal-3 levels are associated with diastolic dysfunction. In obese animals, Gal-3 blockade decreases cardiovascular fibrosis and inflammation. These data suggest that Gal-3 could be a novel therapeutic target in cardiac fibrosis and inflammation associated with obesity.

Galectin-3 blockade inhibits cardiac inflammation and fibrosis in experimental hyperaldosteronism and hypertension.

Hypertensive cardiac remodeling is accompanied by molecular inflammation and fibrosis, 2 mechanisms that finally affect cardiac function. At cardiac level, aldosterone promotes inflammation and fibrosis, although the precise mechanisms are still unclear. Galectin-3 (Gal-3), a ß-galactoside-binding lectin, is associated with inflammation and fibrosis in the cardiovascular system. We herein investigated whether Gal-3 inhibition could block aldosterone-induced cardiac inflammation and fibrosis and its potential role in cardiac damage associated with hypertension. Aldosterone-salt-treated rats presented hypertension, cardiac inflammation, and fibrosis that were prevented by the pharmacological inhibition of Gal-3 with modified citrus pectin. Cardiac inflammation and fibrosis presented in spontaneously hypertensive rats were prevented by modified citrus pectin treatment, whereas Gal-3 blockade did not modify blood pressure levels. In the absence of blood pressure modifications, Gal-3 knockout mice were resistant to aldosterone-induced cardiac inflammation. In human cardiac fibroblasts, aldosterone increased Gal-3 expression via its mineralocorticoid receptor. Gal-3 and aldosterone enhanced proinflammatory and profibrotic markers, as well as metalloproteinase activities in human cardiac fibroblasts, effects that were not observed in Gal-3-silenced cells treated with aldosterone. In experimental hyperaldosteronism, the increase in Gal-3 expression was associated with cardiac inflammation and fibrosis, alterations that were prevented by Gal-3 blockade independently of blood pressure levels. These data suggest that Gal-3 could be a new molecular mechanism linking cardiac inflammation and fibrosis in situations with high-aldosterone levels, such as hypertension.