Prime-boost vaccination regimens with INO-4800 and INO-4802 augment and broaden immune responses against SARS-CoV-2 in nonhuman primates.

The enhanced transmissibility and immune evasion associated with emerging SARS-CoV-2 variants demands the development of next-generation vaccines capable of inducing superior protection amid a shifting pandemic landscape. Since a portion of the global population harbors some level of immunity from vaccines based on the original Wuhan-Hu-1 SARS-CoV-2 sequence or natural infection, an important question going forward is whether this immunity can be boosted by next-generation vaccines that target emerging variants while simultaneously maintaining long-term protection against existing strains. Here, we evaluated the immunogenicity of INO-4800, our synthetic DNA vaccine candidate for COVID-19 currently in clinical evaluation, and INO-4802, a next-generation DNA vaccine designed to broadly target emerging SARS-CoV-2 variants, as booster vaccines in nonhuman primates. Rhesus macaques primed over one year prior with the first-generation INO-4800 vaccine were boosted with either INO-4800 or INO-4802 in homologous or heterologous prime-boost regimens. Both boosting schedules led to an expansion of T cells and antibody responses which were characterized by improved neutralizing and ACE2 blocking activity across wild-type SARS-CoV-2 as well as multiple variants of concern. These data illustrate the durability of immunity following vaccination with INO-4800 and additionally support the use of either INO-4800 or INO-4802 in prime-boost regimens.

Intradermal-delivered DNA vaccine induces durable immunity mediating a reduction in viral load in a rhesus macaque SARS-CoV-2 challenge model.

Coronavirus disease 2019 (COVID-19), caused by the SARS-CoV-2 virus, has had a dramatic global impact on public health and social and economic infrastructures. Here, we assess the immunogenicity and anamnestic protective efficacy in rhesus macaques of an intradermal (i.d.)-delivered SARS-CoV-2 spike DNA vaccine, INO-4800, currently being evaluated in clinical trials. Vaccination with INO-4800 induced T cell responses and induced spike antigen and RBD binding antibodies with ADCP and ADCD activity. Sera from the animals neutralized both the D614 and G614 SARS-CoV-2 pseudotype viruses. Several months after vaccination, animals were challenged with SARS-CoV-2 resulting in rapid recall of anti-SARS-CoV-2 spike protein T cell and neutralizing antibody responses. These responses were associated with lower viral loads in the lung. These studies support the immune impact of INO-4800 for inducing both humoral and cellular arms of the adaptive immune system, which are likely important for providing durable protection against COVID-19 disease.

TGR5 activation induces cytoprotective changes in the heart and improves myocardial adaptability to physiologic, inotropic, and pressure-induced stress in mice.

INTRODUCTION: Administration of cholic acid, or its synthetic derivative, 6-alpha-ethyl-23(S)-methylcholic acid (INT-777), activates the membrane GPCR, TGR5, influences whole body metabolism, reduces atherosclerosis, and benefits the cardiovascular physiology in mice. Direct effects of TGR5 agonists, and the role for TGR5, on myocardial cell biology and stress response are unknown. METHODS: Mice were fed chow supplemented with 0.5% cholic acid (CA) or 0.025% INT-777, a specific TGR5 agonist, or regular chow for 3 weeks. Anthropometric, biochemical, physiologic (electrocardiography and echocardiography), and molecular analysis was performed at baseline. CA and INT-777 fed mice were challenged with acute exercise-induced stress, acute catecholamine-induced stress, and hemodynamic stress induced by transverse aortic constriction (TAC) for a period of 8 weeks. In separate experiments, mice born with constitutive deletion of TGR5 in cardiomyocytes (CM-TGR5del ) were exposed to exercise, inotropic, and TAC-induced stress. RESULTS: Administration of CA and INT-777 supplemented diets upregulated TGR5 expression and activated Akt, PKA, and ERK1/2 in the heart. CA and INT-777 fed mice showed improved exercise tolerance, improved sensitivity to catecholamine and attenuation in pathologic remodeling of the heart under hemodynamic stress. In contrast, CM-TGR5del showed poor response to exercise and catecholamine challenge as well as higher mortality and signs of accelerated cardiomyopathy under hemodynamic stress. CONCLUSIONS: Bile acids, specifically TGR5 agonists, induce cytoprotective changes in the heart and improve myocardial response to physiologic, inotropic, and hemodynamic stress in mice. TGR5 plays a critical role in myocardial adaptability, and TGR5 activation may represent a potentially attractive treatment option in heart failure.

Bile acid excess induces cardiomyopathy and metabolic dysfunctions in the heart.

Cardiac dysfunction in patients with liver cirrhosis is strongly associated with increased serum bile acid concentrations. Here we show that excess bile acids decrease fatty acid oxidation in cardiomyocytes and can cause heart dysfunction, a cardiac syndrome that we term cholecardia. Farnesoid X receptor; Small Heterodimer Partner double knockout mice, a model for bile acid overload, display cardiac hypertrophy, bradycardia, and exercise intolerance. In addition, double knockout mice exhibit an impaired cardiac response to catecholamine challenge. Consistent with this decreased cardiac function, we show that elevated serum bile acids reduce cardiac fatty acid oxidation both in vivo and ex vivo. We find that increased bile acid levels suppress expression of proliferator-activated receptor-γ coactivator 1α, a key regulator of fatty acid metabolism, and that proliferator-activated receptor-γ coactivator 1α overexpression in cardiac cells was able to rescue the bile acid-mediated reduction in fatty acid oxidation genes. Importantly, intestinal bile acid sequestration with cholestyramine was sufficient to reverse the observed heart dysfunction in the double knockout mice. CONCLUSIONS: Decreased proliferator-activated receptor-γ coactivator 1α expression contributes to the metabolic dysfunction in cholecardia so that reducing serum bile acid concentrations may be beneficial against the metabolic and pathological changes in the heart. (Hepatology 2017;65:189-201).

Cardiomyopathy reverses with recovery of liver injury, cholestasis and cholanemia in mouse model of biliary fibrosis.

BACKGROUND: Triggers and exacerbants of cirrhotic cardiomyopathy (CC) are poorly understood, limiting treatment options in patients with chronic liver diseases. Liver transplantation alone reverses some features of CC, but the physiology behind this effect has never been studied. AIMS: We aimed to determine whether reversal of liver injury and fibrosis in mouse affects cardiac parameters. The second aim was to determine whether cardiomyopathy can be induced by specifically increasing systemic bile acid (BA) levels. METHODS: 6-8 week old male C57BL6J mice were fed either chow (n = 5) or 3,5-diethoxycarbonyl-1,4-dihydroxychollidine (DDC) (n = 10) for 3 weeks. At the end of 3 weeks, half the mice in the DDC fed group were randomized to chow (the reversed [REV] group). Serial ECHOs and electrocardiographic analysis was conducted weekly for 6 weeks followed by liver tissue and serum studies. Hearts were analysed for key components of function and cell signalling. Cardiac physiological and molecular parameters were similarly analysed in Abcb11(-/-) mice (n = 5/grp) fed 0.5% cholic acid supplemented diet for 1 week. RESULTS: Mice in the REV group showed normalization of biochemical markers of liver injury with resolution of electrocardiographic and ECHO aberrations. Catecholamine resistance seen in DDC group resolved in the REV group. Cardiac recovery was accompanied by normalization of cardiac troponin-T2 as well as resolution of cardiac stress response at RNA level. Cardiovascular physiological and molecular parameters correlated with degree of cholanemia. Cardiomyopathy was reproduced in cholanemic BA fed Abcb11(-/-) mice. CONCLUSIONS: Cardiomyopathy resolves with resolution of liver injury, is associated with cholanaemia, and can be induced by BA feeding.