Daniel T. Eitzman

Traumatic brain injury (TBI) is associated with increased long-term cardiovascular risk, but strategies to limit post-traumatic vascular disease are lacking. We tested whether empagliflozin, a sodium-glucose cotransporter 2 inhibitor, attenuates TBI-induced atherosclerosis in apolipoprotein E-deficient mice. Mice on a Western diet underwent controlled cortical impact or sham surgery and received empagliflozin or vehicle for 10 weeks. TBI increased aortic plaque burden, aortic-root lesion size, and blood pressure without changing plasma cholesterol, glucose, insulin, or 8-isoprostane. In vehicle-treated mice plasma norepinephrine was higher after TBI but not significantly elevated in TBI mice treated with empagliflozin. Empagliflozin prevented the TBI-associated increases in blood pressure and atherosclerosis. SGLT2 immunoreactivity was detected in smooth muscle cell-rich plaque regions and in cultured murine vascular smooth muscle cells. In vitro, empagliflozin inhibited norepinephrine-induced smooth muscle cell migration and proliferation. These findings show that empagliflozin attenuates TBI-accelerated atherosclerosis independently of measured systemic metabolic changes. Hemodynamic effects and direct effects on vascular smooth muscle cell responses may contribute to this protection.

Traumatic brain injury (TBI) is associated with cardiovascular mortality in humans. Enhanced sympathetic activity following TBI may contribute to accelerated atherosclerosis. The effect of beta1-adrenergic receptor blockade on atherosclerosis progression induced by TBI was studied in apolipoprotein E deficient mice. Mice were treated with metoprolol or vehicle following TBI or sham operation. Mice treated with metoprolol experienced a reduced heart rate with no difference in blood pressure. Six weeks following TBI, mice were sacrificed for analysis of atherosclerosis. Total surface area and lesion thickness, analyzed at the level of the aortic valve, was found to be increased in mice receiving TBI with vehicle treatment but this effect was ameliorated in TBI mice receiving metoprolol. No effect of metoprolol on atherosclerosis was observed in mice receiving only sham operation. In conclusion, accelerated atherosclerosis following TBI is reduced with beta-adrenergic receptor antagonism. Beta blockers may be useful to reduce vascular risk associated with TBI.

Sickle cell disease is a prevalent hematologic condition, but some of the factors that lead to erythrocyte sickling are not fully known. A 58-year-old male patient with a history of sickle cell disease (SCD) and paroxysmal atrial fibrillation was transferred from an outside hospital for further management of refractory sickle cell crisis with acute chest syndrome. Before transfer, the patient received antibiotics and multiple packed red blood cell (pRBC) transfusions, with minimal effect on symptoms or anemia. After transfer, the patient developed rapid supraventricular tachycardia and atrial fibrillation (rates >160) with a drop in blood pressure. He was started on IV amiodarone. His heart rate was subsequently better controlled and converted to sinus rhythm the following day. Three days following initiation of amiodarone, the patient, with a hemoglobin count of 6.4 g/dl, required one additional unit of pRBC. On the fourth day, the patient’s hemoglobin count rose to 9.4 g/dl, and he reported a marked improvement in symptoms. The improvements in symptoms and hemoglobin count were sustained, and the patient was discharged two days later. This remarkable improvement in anemia and symptoms triggered a search for potential causes. Amiodarone is a complex drug shown to have effects on multiple cell types, including erythrocytes. A recent preclinical study demonstrated reduced sickling and improved anemia in a murine model of SCD. This case report raises the possibility that amiodarone may have contributed to the rapid improvement in anemia and should be further explored in clinical trials.

Sickle cell disease (SCD) is associated with altered plasma and erythrocyte lipid profiles. In a previous study, SCD mice with deficiency of proprotein convertase subtilisin/kexin type 9 (PCSK9) were observed to have more severe anemia and increased sickling compared to control SCD mice. Although PCSK9 affects circulating low density lipoprotein (LDL) by regulation of the LDL receptor, the effect of PCSK9 on anemia was independent of LDL receptor expression. In the current study, erythrocyte metabolomics were performed and revealed altered erythrocyte lipid species between SCD mice with and without PCSK9. Of particular interest, the late endosome-specific lipid bis(mono)acylglycerol phosphate (BMP) 44:12 was markedly decreased in erythrocytes from SCD mice deficient in PCSK9 mice relative to control SCD mice. Incubation of sickle erythrocytes with a neutralizing antibody to BMP increased erythrocyte sickling in vitro. In vitro treatment of SCD erythrocytes with amiodarone (1.5 μM) or medroxyprogesterone (6.75 μM), two pharmacologic compounds known to increase BMP, resulted in reduced erythrocyte sickling. Treatment of SCD mice with amiodarone (10 mg/kg) for 2 weeks resulted in increased BMP, improvement in anemia with reduced reticulocytosis, and decreased ex vivo sickling. In conclusion, severity of anemia in SCD is improved with amiodarone treatment, an effect which may be mediated through increased erythrocyte BMP.

Traumatic brain injury (TBI) is associated with cardiovascular mortality in humans. Enhanced sympathetic activity following TBI may contribute to accelerated atherosclerosis. The effect of beta-adrenergic receptor blockade on atherosclerosis progression induced by TBI was studied in apolipoprotein E deficient mice. Mice were treated with metoprolol or vehicle following TBI or sham operation. Mice treated with metoprolol experienced a reduced heart rate with no difference in blood pressure. Six weeks following TBI, mice were sacrificed for analysis of atherosclerosis. Lesion thickness was analyzed at the level of the aortic valve and found to be increased in mice receiving TBI with vehicle treatment but was reduced in TBI mice receiving metoprolol. The increase in lesion thickness was associated with increased percent macrophage immunostaining area of intima which was also reduced with metoprolol. No effect of metoprolol on lesion thickness or macrophage content was observed in mice receiving only sham operation. In conclusion, accelerated atherosclerosis following TBI is reduced with beta-adrenergic receptor antagonism. Beta blockers may be useful to reduce vascular risk associated with TBI.

Sickle cell disease (SCD) is with associated altered plasma and erythrocyte lipid profiles. In a previous study, SCD mice with deficiency of proprotein convertase subtilisin/kexin type 9 (PCSK9) were observed to have more severe anemia and increased sickling compared to control SCD mice. Although PCSK9 affects circulating low density lipoprotein (LDL) by regulation of the LDL receptor, the effect of PCSK9 on anemia was independent of LDL receptor expression. In the current study, erythrocyte metabolomics were performed and revealed altered erythrocyte lipid species between SCD mice with and without PCSK9. Of particular interest, the late endosome-specific lipid bis(mono)acylglycerol phosphate (BMP) 44:12 was markedly decreased in erythrocytes from SCD mice deficient in PCSK9 mice relative to control SCD mice. Incubation of sickle erythrocytes with a neutralizing antibody to BMP increased erythrocyte sickling in vitro. In vitro treatment of SCD erythrocytes with amiodarone (1.5 uM) or medroxyprogesterone (6.75 uM), two pharmacologic compounds known to increase BMP, resulted in reduced erythrocyte sickling. Treatment of SCD mice with amiodarone (10 mg/kg) for 2 weeks resulted in increased BMP, improvement in anemia with reduced reticulocytosis, and decreased ex vivo sickling. In conclusion, severity of anemia in SCD is improved with amiodarone treatment, an effect which may be mediated through increased erythrocyte BMP.

Sickle cell disease (SCD) is associated with haemolytic anaemia and secondary activation of leucocytes and platelets, which in turn may further exacerbate haemolysis. As cytokine signalling pathways may participate in this cycle, the present study investigated whether pharmacological blockade of the interleukin-1 receptor (IL-1R) would mitigate anaemia in a murine model of SCD. Within 2 weeks of treatment, reduced markers of haemolysis were observed in anakinra-treated mice compared to vehicle-treated mice. After 4 weeks of anakinra treatment, mice showed increased numbers of erythrocytes, haemoglobin, and haematocrit, along with reduced reticulocytes. Blood from anakinra-treated mice was less susceptible to ex vivo erythrocyte sickling and was resistant to exogenous IL-1β-mediated sickling. Supernatant generated from IL-1β-treated platelets was sufficient to promote erythrocyte sickling, an effect not observed with platelet supernatant generated from IL-1R^−/− mice. The sickling effect of IL-1β-treated platelet supernatant was inhibited by a transforming growth factor-β (TGF-β) neutralising antibody, nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibition, and superoxide scavengers, but replicated by recombinant TGF-β. In conclusion, pharmacological IL-1R antagonism leads to improved anaemia in a murine SCD model. IL-1β stimulation of platelets promotes erythrocyte sickling. This effect may be mediated by platelet-derived TGF-β-induced reactive oxygen species generation though erythrocyte NADPH oxidase.

As noted by JAHA Editor‐in‐Chief Barry London¹, the views presented in the recently retracted article “Diversity, Inclusion, and Equity: Evolution of Race and Ethnicity Considerations for the Cardiology Workforce in the United States of America From 1969 to 2019”^2,3 do not reflect the views of the JAHA Editorial Board, the Editor‐in‐Chief, or the American Heart Association. We, the JAHA editors, are strong advocates of increasing equity, diversity and inclusiveness in cardiovascular medicine and in healthcare broadly.