Novel Mouse Model of Myocardial Infarction, Plaque Rupture, and Stroke Shows Improved Survival With Myeloperoxidase Inhibition.

BACKGROUND: Thromboembolic events, including myocardial infarction (MI) or stroke, caused by the rupture or erosion of unstable atherosclerotic plaques are the leading cause of death worldwide. Although most mouse models of atherosclerosis develop lesions in the aorta and carotid arteries, they do not develop advanced coronary artery lesions. Moreover, they do not undergo spontaneous plaque rupture with MI and stroke or do so at such a low frequency that they are not viable experimental models to study late-stage thrombotic events or to identify novel therapeutic approaches for treating atherosclerotic disease. This has stymied the development of more effective therapeutic approaches for reducing these events beyond what has been achieved with aggressive lipid lowering. Here, we describe a diet-inducible mouse model that develops widespread advanced atherosclerosis in coronary, brachiocephalic, and carotid arteries with plaque rupture, MI, and stroke. METHODS: We characterized a novel mouse model with a C-terminal mutation in the scavenger receptor class B, type 1 (SR-BI), combined with Ldlr knockout (designated SR-BI∆CT/∆CT/Ldlr-/-). Mice were fed Western diet (WD) for 26 weeks and analyzed for MI and stroke. Coronary, brachiocephalic, and carotid arteries were analyzed for atherosclerotic lesions and indices of plaque stability. To validate the utility of this model, SR-BI∆CT/∆CT/Ldlr-/- mice were treated with the drug candidate AZM198, which inhibits myeloperoxidase, an enzyme produced by activated neutrophils that predicts rupture of human atherosclerotic lesions. RESULTS: SR-BI∆CT/∆CT/Ldlr-/- mice show high (>80%) mortality rates after 26 weeks of WD feeding because of major adverse cardiovascular events, including spontaneous plaque rupture with MI and stroke. Moreover, WD-fed SR-BI∆CT/∆CT/Ldlr-/- mice displayed elevated circulating high-sensitivity cardiac troponin I and increased neutrophil extracellular trap formation within lesions compared with control mice. Treatment of WD-fed SR-BI∆CT/∆CT/Ldlr-/- mice with AZM198 showed remarkable benefits, including >90% improvement in survival and >60% decrease in the incidence of plaque rupture, MI, and stroke, in conjunction with decreased circulating high-sensitivity cardiac troponin I and reduced neutrophil extracellular trap formation within lesions. CONCLUSIONS: WD-fed SR-BI∆CT/∆CT/Ldlr-/- mice more closely replicate late-stage clinical events of advanced human atherosclerotic disease than previous models and can be used to identify and test potential new therapeutic agents to prevent major adverse cardiac events.

The Combination of Vascular Endothelial Growth Factor A (VEGF-A) and Fibroblast Growth Factor 1 (FGF1) Modified mRNA Improves Wound Healing in Diabetic Mice: An Ex Vivo and In Vivo Investigation.

BACKGROUND: Diabetic foot ulcers (DFU) pose a significant health risk in diabetic patients, with insufficient revascularization during wound healing being the primary cause. This study aimed to assess microvessel sprouting and wound healing capabilities using vascular endothelial growth factor (VEGF-A) and a modified fibroblast growth factor (FGF1). METHODS: An ex vivo aortic ring rodent model and an in vivo wound healing model in diabetic mice were employed to evaluate the microvessel sprouting and wound healing capabilities of VEGF-A and a modified FGF1 both as monotherapies and in combination. RESULTS: The combination of VEGF-A and FGF1 demonstrated increased vascular sprouting in the ex vivo mouse aortic ring model, and topical administration of a combination of VEGF-A and FGF1 mRNAs formulated in lipid nanoparticles (LNPs) in mouse skin wounds promoted faster wound closure and increased neovascularization seven days post-surgical wound creation. RNA-sequencing analysis of skin samples at day three post-wound creation revealed a strong transcriptional response of the wound healing process, with the combined treatment showing significant enrichment of genes linked to skin growth. CONCLUSION: f-LNPs encapsulating VEGF-A and FGF1 mRNAs present a promising approach to improving the scarring process in DFU.

Subcutaneous delivery of FGF21 mRNA therapy reverses obesity, insulin resistance, and hepatic steatosis in diet-induced obese mice.

Fibroblast growth factor 21 (FGF21) is a promising therapeutic agent for treatment of type 2 diabetes (T2D) and non-alcoholic steatohepatitis (NASH). We show that therapeutic levels of FGF21 were achieved following subcutaneous (s.c.) administration of mRNA encoding human FGF21 proteins. The efficacy of mRNA was assessed following 2-weeks repeated s.c. dosing in diet-induced obese (DIO), mice which resulted in marked decreases in body weight, plasma insulin levels, and hepatic steatosis. Pharmacokinetic/pharmacodynamic (PK/PD) modelling of several studies in both lean and DIO mice showed that mRNA encoding human proteins provided improved therapeutic coverage over recombinant dosed proteins in vivo. This study is the first example of s.c. mRNA therapy showing pre-clinical efficacy in a disease-relevant model, thus, showing the potential for this modality in the treatment of chronic diseases, including T2D and NASH.

Functionalized lipid nanoparticles for subcutaneous administration of mRNA to achieve systemic exposures of a therapeutic protein.

Lipid nanoparticles (LNPs) are the most clinically advanced delivery system for RNA-based drugs but have predominantly been investigated for intravenous and intramuscular administration. Subcutaneous administration opens the possibility of patient self-administration and hence long-term chronic treatment that could enable messenger RNA (mRNA) to be used as a novel modality for protein replacement or regenerative therapies. In this study, we show that subcutaneous administration of mRNA formulated within LNPs can result in measurable plasma exposure of a secreted protein. However, subcutaneous administration of mRNA formulated within LNPs was observed to be associated with dose-limiting inflammatory responses. To overcome this limitation, we investigated the concept of incorporating aliphatic ester prodrugs of anti-inflammatory steroids within LNPs, i.e., functionalized LNPs to suppress the inflammatory response. We show that the effectiveness of this approach depends on the alkyl chain length of the ester prodrug, which determines its retention at the site of administration. An unexpected additional benefit to this approach is the prolongation observed in the duration of protein expression. Our results demonstrate that subcutaneous administration of mRNA formulated in functionalized LNPs is a viable approach to achieving systemic levels of therapeutic proteins, which has the added benefits of being amenable to self-administration when chronic treatment is required.

Adipose targets for obesity drug development.

The prevalence of obesity is increasing rapidly in most parts of the world and effective therapeutic drugs are urgently needed. The discovery of leptin in 1994 initiated a new understanding of adipose tissue function, and adipose tissue is now known to not only store and release fatty acids, but also to produce a wealth of factors that have an impact on the regulation of body weight and blood glucose homeostasis. Also, adipocytes express proteins that engage signalling pathways playing important roles in fuel substrate and energy metabolism. These proteins constitute a diverse array of adipose target candidates for the development of drugs to treat obesity. Some of these potential targets have been validated and are now in drug development stages, providing hope that the current obesity epidemic can be addressed by effective drug treatments in the near future.

Pharmacological targeting of adipocytes/fat metabolism for treatment of obesity and diabetes.

Obesity is now recognized as a rapidly increasing worldwide threat to health, largely as a result of causing diabetes. Thus, considerable efforts are underway in the pharmaceutical industry to find drugs to treat this condition. Target validation in various academic and industrial laboratories has revealed a number of potential molecular targets in fat cells or adipocytes. By definition, obesity is too much fat, and we here review efforts to treat obesity and, by proxy, diabetes by modulating the metabolic state of adipocytes.

Triglyceride modulation by acifran analogs: activity towards the niacin high and low affinity G protein-coupled receptors HM74A and HM74.

Niacin is known to exert profound beneficial effects on cholesterol levels in humans, although its use is somewhat hampered by the gram quantities necessary to exert effects and the prevalence of compliance-limiting skin flushing side effects that occur. Recently, two G protein-coupled receptors (GPCRs) for niacin were identified and characterized as high (HM74A; GPR109A) and low (HM74; GPR109B) affinity receptors based on the binding affinities of niacin. These receptors also bind acifran (AY-25,712), which is known to modulate lipid levels like niacin, with similar affinities. Twelve analogs of acifran were chemically synthesized. One analogue demonstrated a dose-dependent decrease in serum triglycerides in rats within 3h of oral administration. Next, the acifran analogs were assessed for their activity towards the high and low affinity niacin receptors expressed in CHO-K1 cells. Constructs expressing HM74A or HM74 were stably transfected into CHO-K1 cells and shown to elicit phosphorylation of p42 and p44 mitogen-activated protein kinase (ERK1/ERK2) phosphorylation upon addition of niacin or acifran. The presence of functionally coupled GPCRs was further confirmed using Pertussis toxin, which completely inhibited the ability of either niacin or acifran to elicit phospho-ERK1/ERK2. The EC(50) of p-ERK1/ERK2 for niacin for the high and low affinity receptors was 47nM and indeterminate (i.e., >100microM), respectively, while the EC(50) for acifran was 160 and 316nM, respectively. Two chemical analogs of acifran demonstrated robust phosphorylation of ERK1/ERK2. Collectively, these data suggest that the synthesis of acifran analogs may be a suitable path for developing improved HM74A agonists.

Leporin B: a novel hexokinase II gene inducing agent from an unidentified fungus.

Leporin B (1), a novel demethylated analogue of leporin A (2), was isolated from a taxonomically unidentified fungal strain as part of an effort to discover compounds with the ability to increase expression levels of the enzyme hexokinase II. The structure was determined by spectral methods, including 1D and 2D NMR, and HRMS. The relative stereochemistry was assigned by NOESY experiments and coupling constants.