SGLT-2 inhibition by empagliflozin exerts neutral effects on experimental arterial thrombosis in a murine model of low-grade inflammation

Introduction

Low-grade inflammation couples dysmetabolic states to insulin resistance and atherosclerotic cardiovascular disease (ASCVD). Selective sodium-glucose co-transporter 2 (SGLT-2) inhibition by empagliflozin improves clinical outcomes in patients with ASCVD independently of glucose-lowering. Yet, its mechanism of action remains largely undetermined.

Purpose

We aimed to test whether empagliflozin affects arterial thrombus formation in baseline conditions or low-grade inflammation, a systemic milieu shared among patients with ASCVD.

Methods

Sixteen-week-old C57BL/6 mice were randomly assigned to acute administration of empagliflozin (25 mg/kg BW) or vehicle, of which a subgroup was pre-treated biweekly over 4 weeks with super-low-dose lipopolysaccharide (LPS; 5 ng/kg BW), before carotid thrombosis was induced by photochemical injury. The translational value of these findings was investigated in primary human aortic endothelial cells (HAECs) and plasma samples of patients randomized to empagliflozin therapy.

Results

The between-group difference in doppler-flow probe detected time-to-occlusion (TTO) remained within the predefined equivalence margin (Δ=|10.50|), irrespective of low-grade inflammation (95% confidence interval [CI], −9.82 to 8.85 and −9.20 to 9.69), while glucose dropped by 1.64 and 4.84 mmol/l, respectively (Fig. 1). Ex vivo platelet aggregometry suggests similar platelet activation status, corroborated by unchanged circulating platelet-factor 4 (PF4) plasma levels. In concert, carotid PAI-1 expression and TF activity remained unaltered upon SGLT-2 inhibition, and no difference in plasma D-dimer levels was detected, suggesting comparable coagulation cascade activation and fibrinolytic activity (Fig. 1). In HAECs pre-treated with LPS, empagliflozin neither changed TF activity nor PAI-1 expression (Fig. 2). Accordingly, among patients with established ASCVD or at high cardiovascular (CV) risk randomized to 10 mg empagliflozin daily signatures of thrombotic (i.e., TF) and fibrinolytic activity (i.e., PAI-1) remained unchanged, while plasma glucose declined significantly during 3 months of follow-up (Fig. 2).

Conclusion

SGLT-2 inhibition by empagliflozin does not impact experimental arterial thrombus formation, neither under baseline conditions nor during sustained low-grade inflammation, and has no impact on proxies of thrombotic/fibrinolytic activity in patients with ASCVD. The beneficial pleiotropic effects of empagliflozin are likely independent of pathways mediating thrombosis.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Swiss National Science FoundationSwiss Heart FoundationFoundation for Cardiovascular Research–Zurich Heart House

The role of matrix metalloproteinase-2 on age-dependent arterial stiffness

Introduction

Arterial stiffness is a well-characterized sign of vascular aging. It strongly predicts the development of several cardiovascular diseases (CVD), such as hypertension, stroke and heart failure. The age-dependent stiffening of elastic arteries is primarily attributed to the loss of interlaminar elastic fibers and the increase of collagen fibers. This process is regulated by matrix metalloproteinases (MMPs), including MMP-2. A strong correlation between MMP-2 levels and arterial stiffness has been previously described. However, the causative link between age-dependent arterial stiffness and MMP-2 remains unclear.

Purpose

In this study, we aimed to prospectively investigate the effect of MMP-2 gene silencing on the development of age-dependent carotid stiffness in wild type (WT) mice.

Methods

Pulse Wave Velocity (PWV), as the gold standard technique to assess arterial stiffness, was assessed in the right common carotid artery (RCCA) of C57BL/6 WT mice of various ages ranging between 3 and 25 months. Plasma and vascular levels of MMP-2 on RCCA were also measured and correlate with PWV. Moreover, aged WT male mice (18–21-month-old) were treated for 4 weeks with either MMP-2 siRNA or Scr siRNA via tail vein injection every 4 days and PWV was assessed at baseline, 2 and 4 weeks.

Results

Mouse carotid PWV increased and was positively correlated with age in our in vivo longitudinal study. Increases of vascular and circulating MMP-2 levels were also observed in this study. MMP-2 knockdown by siRNA treatment reduced vascular MMP-2 level (Fig. 1), which in turn attenuated age-dependent carotid stiffening (data not shown). siMMP-2 treated animals also showed an increase of elastin to collagen ratio. Furthermore, enhanced phosphorylation of the activatory eNOS Ser1177 was observed in the siMMP-2 group without affecting the level of total eNOS and Akt phosphorylation. Interestingly, co-immunoprecipitation experiments demonstrated that MMP-2 directly interacts with eNOS and this interaction is augmented with age.

Conclusion

The silencing of MMP-2 attenuates age-dependent carotid stiffness by affecting elastin to collagen ratio and interfering with eNOS activation. Thus, MMP-2 may mediate ECM remodeling and endothelial-dependent vasorelaxation in the development of age-dependent vascular stiffness.

Funding Acknowledgement

Type of funding source: Foundation. Main funding source(s): Swiss National Science Foundation, Foundation for Cardiovascular Research-Zurich Heart House

In-vitro phagocytosis and intracellular killing of Pasteurella multocida B:2 by phagocytic cells of buffaloes

Pasteurella multocida B:2 is a Gram-negative organism causing haemorrhagic septicaemia (HS) in buffaloes. It causes severe pulmonary infection, leading to infiltration of numerous macrophages and neutrophils. Despite the inflammatory response, buffaloes succumb to HS. This study aims to evaluate the in-vitro efficacy of macrophages and neutrophils of buffalo following exposure to P. multocida B:2. In-vitro infections were done using 10⁷ cfu/ml of P. multocida B:2 for Group 1, Escherichia coli for Group 2 and Mannhaemia haemolytica A:2 for Group 3 cells. The inoculated cell cultures were harvested at 0, 30, 60 and 120 min post-exposure and the phagocytic, killing and cell death rates were determined. Both phagocytosis and killing rates of all bacteria increased over time. Phagocytosis involved between 71% and 73% neutrophils and between 60% and 64% macrophages at 120 min. Killing rate of all bacteria involved between 76% and 79% for neutrophils and between 70% and 74% for macrophages at 120 min. Death rate of neutrophils ranged between 67% in Group 3, and 88% in Group 1 at 120 min, significantly (p < 0.05) higher than Group 3 but insignificant (p > 0.05) than Group 2. Similar pattern was observed for death rate of macrophages. The phagocytosis and killing rates of P. multocida B:2 were similar to other bacterial species used in this study but more neutrophils and macrophages were dead following infection by P. multocida B:2 than M. haemolytica A:2.