Efficacy of Ganshuang granules on non-alcoholic fatty liver and underlying mechanism: a network pharmacology and experimental verification

OBJECTIVE

To investigate the potential pharmacological mechanisms of Ganshuang granules (, GSG) in treating non-alcoholic fatty liver (NAFLD).

METHODS

All the active components and targets of GSG were retrieved from the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform. Protein-Protein interaction network, Kyoto Encyclopedia of Genes and Genomes and Gene Ontology function annotation of common targets were analyzed to predict the mechanisms of action of GSG in the treatment of NAFLD. Then, the mouse models of NAFLD were constructed in a diet-induced manner and treated with GSG. The levels of interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-α) and phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) pathway-related proteins in the liver of mice in each group were measured by enzyme linked immunosorbent assay and Western blot, respectively.

RESULTS

Network pharmacology revealed a total of 159 potential targets of GSG for the treatment of NAFLD. Functional enrichment analysis indicated that the PI3K/AKT signaling pathway may be involved during GSG treatment of NAFLD. Further experiments showed that the significantly decreased alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, total cholesterol, triglyceride and low-density lipoprotein cholesterol levels in NAFLD model mice serum after GSG treatment, as well as the expression levels of IL-6 and TNF-α in the liver. Furthermore, drug intervention increased the protein expression levels of phosphorylated-PI3K (P-PI3K) and P-AKT in the liver of the model group mice, and decreased the protein expression level of sterol regulatory element-binding protein 1.

CONCLUSION

We found that GSG is effective in treating NAFLD and the potential therapeutic targets may be involved in PI3K/AKT signaling pathway.

Cyclosporine A Does Not Mitigate Liver Ischemia/Reperfusion Injury in an Ex Vivo Porcine Model of Donation After Circulatory Death

BACKGROUND Ischemia/reperfusion injury (IRI) is an inherent problem in organ transplantation, owing to the obligate period of ischemia that organs must endure. Cyclosporine A (CsA), though better know as an immunosuppressant, has been shown to mitigate warm IRI in a variety of organ types, including the liver. However, there is little evidence for CsA in preventing hepatic IRI in the transplant setting. MATERIAL AND METHODS In the present study, we tested the effect of CsA on hepatic IRI in a large-animal ex vivo model of donation after circulatory death (DCD). Porcine donors were pre-treated with either normal saline control or 20 mg/kg of CsA. Animals were subject to either 45 or 60 minutes of warm ischemia before hepatectomy, followed by 2 or 4 hours of cold storage prior to reperfusion on an ex vivo circuit. Over the course of a 12-hour perfusion, perfusion parameters were recorded and perfusate samples and biopsies were taken at regular intervals. RESULTS Peak perfusate lactate dehydrogenase was significantly decreased in the lower-ischemia group treated with CsA compared to the untreated group (4220 U/L [3515-5815] vs 11 305 [10 100-11 674]; P=0.023). However, no difference was seen between controls and CsA-treated groups on other parameters in perfusate alanine or asparagine aminotransferase (P=0.912, 0.455, respectively). Correspondingly, we found no difference on midpoint histological injury score (P=0.271). CONCLUSIONS We found minimal evidence that CsA is protective against hepatic IRI in our DCD model.

Combined Treatment of Human Induced Pluripotent Stem Cell-Derived Cardiomyocytes and Endothelial Cells Regenerate the Infarcted Heart in Mice and Non-Human Primates

BACKGROUND

Remuscularization of the mammalian heart can be achieved after cell transplantation of human induced pluripotent stem cell (hiPSC)-derived cardiomyocytes (CMs). However, several hurdles remain before implementation into clinical practice. Poor survival of the implanted cells is related to insufficient vascularization, and the potential for fatal arrhythmogenesis is associated with the fetal cell-like nature of immature CMs.

METHODS

We generated 3 lines of hiPSC-derived endothelial cells (ECs) and hiPSC-CMs from 3 independent donors and tested hiPSC-CM sarcomeric length, gap junction protein, and calcium-handling ability in coculture with ECs. Next, we examined the therapeutic effect of the cotransplantation of hiPSC-ECs and hiPSC-CMs in nonobese diabetic-severe combined immunodeficiency (NOD-SCID) mice undergoing myocardial infarction (n≥4). Cardiac function was assessed by echocardiography, whereas arrhythmic events were recorded using 3-lead ECGs. We further used healthy non-human primates (n=4) with cell injection to study the cell engraftment, maturation, and integration of transplanted hiPSC-CMs, alone or along with hiPSC-ECs, by histological analysis. Last, we tested the cell therapy in ischemic reperfusion injury in non-human primates (n=4, 3, and 4 for EC+CM, CM, and control, respectively). Cardiac function was evaluated by echocardiography and cardiac MRI, whereas arrhythmic events were monitored by telemetric ECG recorders. Cell engraftment, angiogenesis, and host-graft integration of human grafts were also investigated.

RESULTS

We demonstrated that human iPSC-ECs promote the maturity and function of hiPSC-CMs in vitro and in vivo. When cocultured with ECs, CMs showed more mature phenotypes in cellular structure and function. In the mouse model, cotransplantation augmented the EC-accompanied vascularization in the grafts, promoted the maturity of CMs at the infarct area, and improved cardiac function after myocardial infarction. Furthermore, in non-human primates, transplantation of ECs and CMs significantly enhanced graft size and vasculature and improved cardiac function after ischemic reperfusion.

CONCLUSIONS

These results demonstrate the synergistic effect of combining iPSC-derived ECs and CMs for therapy in the postmyocardial infarction heart, enabling a promising strategy toward clinical translation.

The effect of aerobic and resistance exercise on the progression of colorectal cancer in an animal model

PURPOSE

The aim of this study was to assess the effects of resistance and aerobic exercise on colorectal cancer (CRC) development in mice induced by azoxymethane (AOM) coupled with colitis.

METHODS

Forty animals induced with CRC were used, divided into five groups of eight animals each: sedentary; continuous aerobics; continuous anaerobic; aerobic PI; and anaerobic PI. AOM was administered to the animals in two doses of 10 mg/kg each over the course of two weeks, the first dose administered in the third week and the second administered in the fourth. For the colitis, three cycles of dextran sodium sulfate were administered for five days, separated by two weeks of water. The 14th week of the experiment saw the euthanasia, the removal of their colons, and the creation of microscopy slides for histological analysis.

RESULTS

Preneoplastic lesions developed in all five groups; there were no significant differences between them. However, in terms of inflammatory symptoms, mucosal ulceration was much more frequently in the exercise groups than in the sedentary group (p = 0.016). The number of polyps overall (p = 0.002), the distal region's polyp development (p = 0.003), and the proximal region's polyp development (p = 0.04) were all statistically different than sedentary group.

CONCLUSIONS

The study discovered no significant difference in disease activity index scores between groups, but there was a significant difference in the number of polyps and the presence of mucosal ulceration in the colon.

Does fasting protect liver from ischemia and reperfusion injury?

PURPOSE

To evaluate local and systemic effects of 24-hour fasting in liver ischemia and reperfusion injury.

METHODS

Twenty-one adult male Wistar rats (330-390 g) were submitted to 60 minutes of hepatic ischemia followed by 24 hours of reperfusion. Before the day of the experiment, the animals fasted, but free access to water was allowed. Two groups were constituted: Control: non-fasted, that is, feeding ad libitum before surgical procedure; Fasting: rats underwent previous fasting of 24 hours. Hepatic ischemia was performed using vascular clamp in hepatic pedicle. At 24 hours after liver reperfusion, blood and tissue samples were collected. To analysis, liver lobes submitted to ischemia was identified as ischemic liver and paracaval non-ischemic lobes as non-ischemic liver. We evaluated: malondialdehyde levels, hepatocellular function (alanine aminotransferase, aspartate aminotransferase activities, and both ratio), cytokines (interleukins-6, -10, and tumor necrosis factor-alpha), hepatic ischemia and reperfusion injury (histology).

RESULTS

Malondialdehyde measured in non-ischemic and ischemic liver samples, hepatocellular function and cytokines were comparable between groups. Histological findings were distinct in three regions evaluated. Microvesicular steatosis was comparable between 24-hour fasting and non-fasted control groups in periportal region of hepatic lobe. In contrast, steatosis was more pronounced in zones 2 and 3 of ischemic liver samples of fasting compared to control groups.

CONCLUSIONS

These data indicates that fasting does not protect, but it can be also detrimental to liver submitted to ischemia/reperfusion damage. At that time, using long fasting before liver surgery in the real world may be contraindicated.

Mucin levels in glands of the colonic mucosa of rats with diversion colitis subjected to enemas containing sucralfate and n-acetylcysteine alone or in combination

PURPOSE

To evaluate the tissue content of neutral and acidic mucins, sulfomucins and sialomucins in colonic glands devoid of intestinal transit after enemas containing sucralfate and n-acetylcysteine alone or in combination.

METHODS

Sixty-four rats underwent intestinal transit bypass. A colonic segment was collected to compose the white group (without intervention). After derivation, the animals were divided into two groups according to whether enemas were performed daily for two or four weeks. Each group was subdivided into four subgroups according to the substance used: control group: saline 0.9%; sucralfate group (SCF): SCF 2 g/kg/day; n-acetylcysteine group (NAC): NAC 100 mg/kg/day; and SCF+NAC group: SCF 2 g/kg/day + NAC 100 mg/kg/day.Neutral and acidic mucins were stained by periodic acid-Schiff and alcian-blue techniques, respectively. The distinction between sulfomucins and sialomucin was made by the high alcian-blue iron diamine technique. The content of mucins in the colonic glands was measured by computerized morphometry. The inflammatory score was assessed using a validated scale. The results between the groups were compared by the Mann-Whitney's test, while the variation according to time by the Kruskal-Wallis' test (Dunn's post-test). A significance level of 5% was adopted.

RESULTS

There was reduction in the inflammatory score regardless of the application of isolated or associated substances. Intervention with SCF+NAC increased the content of all mucin subtypes regardless of intervention time.

CONCLUSIONS

The application of SCF+NAC reduced the inflammatory process of the colonic mucosa and increased the content of different types of mucins in the colonic glands of segments excluded from fecal transit.

Effects of atelectatic areas on the surrounding lung tissue during mechanical ventilation in an experimental model of acute lung injury induced by lipopolysaccharide

OBJECTIVE

To assess the effect of atelectasis during mechanical ventilation on the periatelectatic and normal lung regions in a model of atelectasis in rats with acute lung injury induced by lipopolysaccharide.

METHODS

Twenty-four rats were randomized into the following four groups, each with 6 animals: the Saline-Control Group, Lipopolysaccharide Control Group, Saline-Atelectasis Group, and Lipopolysaccharide Atelectasis Group. Acute lung injury was induced by intraperitoneal injection of lipopolysaccharide. After 24 hours, atelectasis was induced by bronchial blocking. The animals underwent mechanical ventilation for two hours with protective parameters, and respiratory mechanics were monitored during this period. Thereafter, histologic analyses of two regions of interest, periatelectatic areas and the normally-aerated lung contralateral to the atelectatic areas, were performed.

RESULTS

The lung injury score was significantly higher in the Lipopolysaccharide Control Group (0.41 ± 0.13) than in the Saline Control Group (0.15 ± 0.51), p < 0.05. Periatelectatic regions showed higher lung injury scores than normally-aerated regions in both the Saline-Atelectasis (0.44 ± 0.06 x 0.27 ± 0.74 p < 0.05) and Lipopolysaccharide Atelectasis (0.56 ± 0.09 x 0.35 ± 0.04 p < 0.05) Groups. The lung injury score in the periatelectatic regions was higher in the Lipopolysaccharide Atelectasis Group (0.56 ± 0.09) than in the periatelectatic region of the Saline-Atelectasis Group (0.44 ± 0.06), p < 0.05.

CONCLUSION

Atelectasis may cause injury to the surrounding tissue after a period of mechanical ventilation with protective parameters. Its effect was more significant in previously injured lungs.

Characterization of the Masquelet Induced Membrane Technique in a Murine Segmental Bone Defect Model

Objective  To reproduce in an animal model the surgical technique of Masquelet used in the treatment of critical bone defects and to analyze the characteristics of the membrane formed around the bone cement. Methods  A 10mm critical defect was created in the femoral shaft of 21 Sprague-Dawley rats. After resection of the central portion of the diaphysis, the defect was stabilized with a Kirschner wire introduced through the medullary canal and with the interposition of a bone cement spacer. After 2, 4, and 6 weeks of the surgical procedure, the animals were euthanized and evaluated on radiographs of the posterior limb regarding the size of the defect, alignment and stability of the osteosynthesis. The membranes formed around the spacer were subjected to histological analysis to assess thickness, connective tissue maturation and vascular density. Results  Over time, the membranes initially made up of loose connective tissue were replaced by membranes represented by dense connective tissue, rich in thick collagen fibers. At six weeks, membrane thickness was greater (565 ± 208μm) than at four (186.9 ± 70.21μm, p = 0.0002) and two weeks (252.2 ± 55.1μm, p = 0.001). All membranes from the initial time showed foci of osteogenic differentiation that progressively reduced over time. Conclusion  In addition to the structural and protective function of the membrane, its intrinsic biological characteristics can actively contribute to bone regeneration. The biological activity attributed by the presence of foci of osteogenesis confers to the membrane the potential of osteoinduction that favors the local conditions for the integration of the bone graft.

Animal Model Standardization for Studying Avascular Necrosis of the Femoral Head in Legg-Calvé-Perthes Disease

Objective  Testing an experimental model for ischemic necrosis of the femoral head in Legg-Calvé-Perthes disease by evaluating gait, imaging and morphohistology. Methods  The operation was done in 11 piglets. Necrosis by cerclage in the right femoral neck was induced. Piglets were divided into group A, with 8 animals, euthanizing two in the 2 nd , 4 th , 6 th , and 8 th weeks, respectively; and group B, with 2 animals ( sham ), submitted to the surgical procedure without cerclage of the right femoral neck. The gait classification used was that of Etterlin. The frozen femurs were submitted to digital radiography and computed tomography. The height and width of the epiphysis and epiphysary coefficient were measured at study times. Light microscopy and immunohistochemistry with TGF-β1 were performed. Results  One animal died of sepsis in Group A. In this group, claudication was observed in all animals. On digital radiography and computed tomography, bone sclerosis, enlargement of the right femoral neck, flattening, collapse, and fragmentation of the right femoral head were observed. All epiphysis height and epiphysary coefficient values of the right femoral head were lower than the contralateral ones, in which were observed chondrocytes disordered and separated by gaps. A reduction in TGF-β1 expression was observed at 2 and 6 weeks in the right femoral head and at eight in the left. In group B, there were no signs of necrosis and gait was normal. Conclusions  The model presented reproduced macroscopic necrosis on digital radiography, computed tomography, and microscopy. Gait evaluation showed a good correlation with other ischemia findings. Level of Evidence  V. Diagnostic studies.

Gastrotomy followed by gastrorrhaphy as a reliable and more physiologic technique for inducing peritoneal adhesion in rats

OBJECTIVE

this research objective was to develop a new peritoneal adhesion animal model that would lead to adhesions formation in all operated animals, simple and reproducible, associated with maintenance the animal's health.

METHODS

eighteen adult male Wistar rats (Rattus norvegicus) were randomly distributed into three groups: Control Group (anatomical and clinical parameters), Sham Group (delicate manipulation of the stomach and exposure of the peritoneal cavity to ambient air) and Surgery Group (gastrotomy followed by gastrorrhaphy). The animals were analyzed and classificated macroscopically according to two adhesion classification models and differences between groups were considered significant when p<0.05.

RESULTS

the six animals in the control group had no peritoneal adhesions, three of the six animals in the sham group had focal peritoneal adhesions, and all animals in the surgery group (gastrotomy followed by gastrorraphy) had firm peritoneal adhesions. All adhesions found were macroscopically quantified and microscopically confirmed, without carrying out a microscopic classification of the adhesions.

CONCLUSION

the new model developed of gastrotomy followed by gastrorrhaphy, proved to be safe and efficient to induce and study peritoneal adhesions.

COVID-19, Myocarditis and Pericarditis

Viral infections are a leading cause of myocarditis and pericarditis worldwide, conditions that frequently coexist. Myocarditis and pericarditis were some of the early comorbidities associated with SARS-CoV-2 infection and COVID-19. Many epidemiologic studies have been conducted since that time concluding that SARS-CoV-2 increased the incidence of myocarditis/pericarditis at least 15× over pre-COVID levels although the condition remains rare. The incidence of myocarditis pre-COVID was reported at 1 to 10 cases/100 000 individuals and with COVID ranging from 150 to 4000 cases/100 000 individuals. Before COVID-19, some vaccines were reported to cause myocarditis and pericarditis in rare cases, but the use of novel mRNA platforms led to a higher number of reported cases than with previous platforms providing new insight into potential pathogenic mechanisms. The incidence of COVID-19 vaccine-associated myocarditis/pericarditis covers a large range depending on the vaccine platform, age, and sex examined. Importantly, the findings highlight that myocarditis occurs predominantly in male patients aged 12 to 40 years regardless of whether the cause was due to a virus-like SARS-CoV-2 or associated with a vaccine-a demographic that has been reported before COVID-19. This review discusses findings from COVID-19 and COVID-19 vaccine-associated myocarditis and pericarditis considering the known symptoms, diagnosis, management, treatment, and pathogenesis of disease that has been gleaned from clinical research and animal models. Sex differences in the immune response to COVID-19 are discussed, and theories for how mRNA vaccines could lead to myocarditis/pericarditis are proposed. Additionally, gaps in our understanding that need further research are raised.

Effect of β3-adrenoceptor agonist on the micromotion of bilateral major pelvic ganglion-excised rat bladder

AIMS

Micromotion is an autonomous intramural movement of the bladder, and is believed to be an initial step in the generation of urinary urgency. Therefore, controlling micromotion may be a novel target in overactive bladder (OAB) treatment. However, developing micromotion treatment has been limited by the absence of a standardized animal model. We attempted to create a micromotion animal model and investigated the effectiveness of a β₃ -adrenoceptor agonist (CL316,243) on micromotion.

METHODS

Bilateral major pelvic ganglia (MPGs) were excised in 18 male Sprague-Dawley rats, resulting in an almost completely denervated bladder. On postoperative Day 7, cystometry was performed. Rats were divided into three treatment groups: CL316,243; β_3- adrenoceptor antagonist (SR59230A) pretreated CL316,243; and a nonselective antimuscarinic agent (oxybutynin). Changes in micromotion were evaluated after the intra-arterial administration of each agent.

RESULTS

Low-amplitude oscillations in intravesical pressure (micromotion) were observed 1 week after MPGs excision. Micromotion frequency significantly (p = 0.003) decreased (2.17 ± 3.54 times/5 min) with CL316,243 compared with vehicle (6.33 ± 1.97 times/5 min). Micromotion amplitude also decreased with CL316,243 (1.15 ± 1.93 cmH₂ O) compared with vehicle (5.96 ± 5.12 cmH₂ O), approaching conventional significance (p = 0.090). No significant decreases in frequency or amplitude were observed with oxybutynin treatment.

CONCLUSIONS

Systemic administration of the β₃ -adrenoceptor agonist CL316,243 effectively controlled micromotion in bilateral MPGs-excised, almost completely denervated rat bladders. This result indicates that β₃ -adrenoceptor agonist may affect the bladder directly, suggesting that it might be effective for overall OAB, regardless of the presence or level of neurological deficits. Bilateral MPGs-excised rats are considered a plausible micromotion animal model suitable for future research.

NLRP3 inflammasome inhibitor MCC950 can reduce the damage of pancreatic and intestinal barrier function in mice with acute pancreatitis

PURPOSE

Abnormal activation of NOD-like receptor protein 3 (NLRP3) inflammasome can lead to the occurrence and progression of acute pancreatitis. This study investigated the protective effect of MCC950 on pancreatitis mice.

METHODS

Eighteen mice were randomly divided into control group, severe acute pancreatitis (SAP) group and SAP+MCC950 group. Serum interleukin (IL)-1β, IL-6 and tumor necrosis factor-α (TNF-α) were measured by ELISA. Hematoxylin and eosin (HE) staining was used to evaluate the pathological damage. Western blotting was used to detect the expression of NLRP3 inflammasome and tight junction proteins in the small intestine and pancreas.

RESULTS

MCC950 could reduce the levels of IL-6 and IL-1β in SAP mice. After treatment with MCC950, the expression levels of NLRP3 inflammasome in the pancreas of SAP mice were significantly reduced and the pathological damage to the pancreas and intestine was alleviated. Compared with the control group, the expression of tight junction protein (ZO-1,occludin and claudin-4) in the intestinal mucosa of SAP mice was decreased, and the expression of claudin-4 and occludin were upregulated after MCC950 treatment.

CONCLUSIONS

MCC950 can inhibit NLRP3 inflammasome activation and significantly reduce the inflammatory response and delay the process of pancreatitis. It has therapeutic potential in the treatment of acute pancreatitis.

Ceramide nanoliposomes augment the efficacy of venetoclax and cytarabine in models of acute myeloid leukemia

Despite several new therapeutic options for acute myeloid leukemia (AML), disease relapse remains a significant challenge. We have previously demonstrated that augmenting ceramides can counter various drug-resistance mechanisms, leading to enhanced cell death in cancer cells and extended survival in animal models. Using a nanoscale delivery system for ceramide (ceramide nanoliposomes, CNL), we investigated the effect of CNL within a standard of care venetoclax/cytarabine (Ara-C) regimen. We demonstrate that CNL augmented the efficacy of venetoclax/cytarabine in in vitro, ex vivo, and in vivo models of AML. CNL treatment induced non-apoptotic cytotoxicity, and augmented cell death induced by Ara-C and venetoclax. Mechanistically, CNL reduced both venetoclax (Mcl-1) and cytarabine (Chk1) drug-resistant signaling pathways. Moreover, venetoclax and Ara-C augmented the generation of endogenous pro-death ceramide species, which was intensified with CNL. Taken together, CNL has the potential to be utilized as an adjuvant therapy to improve outcomes, potentially extending survival, in patients with AML.

Assessment of stress and anxiety in mice with colorectal cancer submitted to physical exercise

PURPOSE

To evaluate the effect of physical exercise on the behavior of rodents with colorectal cancer induced through the use of elevated plus maze.

METHODS

We used 40 male hairless mice induced to colorectal cancer, divided into five groups: G1) submitted to pre- and post-induction swimming; G2) pre- and post-induction ladder; G3) post-induction swimming; G4) post-induction ladder; G5) sedentary. At the end of the 14th week, the animals were submitted to the plus maze test.

RESULTS

The mean length of stay in the open arm for G1 was 4.17 ± 6.50; G2 37.52 ± 40.7; G3 85.84 ± 42.5; G4 32.92 ± 23.17; and G5 4.09 ± 4.43. In the closed arm, it was 264 ± 23.43 in G1, 187.60 ± 47.73 in G2, 147.50 ± 40.03 in G3, 182.00 ± 40.40 in G4, and in G5 235.36 ± 14.28. In the center, G1 remained 31.86 ± 20.18, G2 74.85 ± 28.37, G3 66.69 ± 19.53, G4 60.55 ± 10.46, and G5 60.55 ± 23.65.

CONCLUSIONS

Aerobic exercise for seven weeks after tumor induction showed less impact on the behavior of the animals. On the other hand, it significantly increased the animals' stress level when applied for 14 weeks before and after tumor induction.

Animal Models of Exercise From Rodents to Pythons

Acute and chronic animal models of exercise are commonly used in research. Acute exercise testing is used, often in combination with genetic, pharmacological, or other manipulations, to study the impact of these manipulations on the cardiovascular response to exercise and to detect impairments or improvements in cardiovascular function that may not be evident at rest. Chronic exercise conditioning models are used to study the cardiac phenotypic response to regular exercise training and as a platform for discovery of novel pathways mediating cardiovascular benefits conferred by exercise conditioning that could be exploited therapeutically. The cardiovascular benefits of exercise are well established, and, frequently, molecular manipulations that mimic the pathway changes induced by exercise recapitulate at least some of its benefits. This review discusses approaches for assessing cardiovascular function during an acute exercise challenge in rodents, as well as practical and conceptual considerations in the use of common rodent exercise conditioning models. The case for studying feeding in the Burmese python as a model for exercise-like physiological adaptation is also explored.

Animal Models of Dysregulated Cardiac Metabolism

As a muscular pump that contracts incessantly throughout life, the heart must constantly generate cellular energy to support contractile function and fuel ionic pumps to maintain electrical homeostasis. Thus, mitochondrial metabolism of multiple metabolic substrates such as fatty acids, glucose, ketones, and lactate is essential to ensuring an uninterrupted supply of ATP. Multiple metabolic pathways converge to maintain myocardial energy homeostasis. The regulation of these cardiac metabolic pathways has been intensely studied for many decades. Rapid adaptation of these pathways is essential for mediating the myocardial adaptation to stress, and dysregulation of these pathways contributes to myocardial pathophysiology as occurs in heart failure and in metabolic disorders such as diabetes. The regulation of these pathways reflects the complex interactions of cell-specific regulatory pathways, neurohumoral signals, and changes in substrate availability in the circulation. Significant advances have been made in the ability to study metabolic regulation in the heart, and animal models have played a central role in contributing to this knowledge. This review will summarize metabolic pathways in the heart and describe their contribution to maintaining myocardial contractile function in health and disease. The review will summarize lessons learned from animal models with altered systemic metabolism and those in which specific metabolic regulatory pathways have been genetically altered within the heart. The relationship between intrinsic and extrinsic regulators of cardiac metabolism and the pathophysiology of heart failure and how these have been informed by animal models will be discussed.

Biofilm model on mice skin wounds

PURPOSE

To evaluate a biofilm model of Pseudomonas aeruginosa in excisional cutaneous wound in mice.

METHODS

Preclinical, translational study conducted with 64 C57BL/6 mice randomly assigned to control and intervention groups. Evaluation was on days D0, D3, D5, D7 and D10 of wound making. The profile of biofilm formation and induction was evaluated using wound closure kinetics, quantitative culture, and evaluation of wounds using transmission electron microscopy (TEM). Clinical evaluation was performed by liver tissue culture, weight variation, and quantification of leukocytes in peripheral blood. Analyses were performed with GraphPad Prism software.

RESULTS

Bacterial load for induction of infection with P. aeruginosa and survival of animals was 104 UFC·mL-1. In D5 (p < 0.0001) and D7 (p < 0.01), animals in the intervention group showed a delay in the healing process and had their wounds covered by necrotic tissue until D10. Statistical differences were observed in wound cultures and weight at D5 and D7 (p < 0.01). Liver cultures and leukocyte quantification showed no statistical differences. No bacteria in planktonic or biofilm form were identified by TEM.

CONCLUSIONS

The findings raise questions about the understanding of the ease of formation and high occurrence of biofilm in chronic wounds.

Genetic Basis of Left Ventricular Noncompaction

BACKGROUND

Left ventricular noncompaction (LVNC) is the third most common pediatric cardiomyopathy characterized by a thinned myocardium and prominent trabeculations. Next-generation genetic testing has led to a rapid increase in the number of genes reported to be associated with LVNC, but we still have little understanding of its pathogenesis. We sought to grade the strength of the gene-disease relationship for all genes reported to be associated with LVNC and identify molecular pathways that could be implicated.

METHODS

Following a systematic PubMed review, all genes identified with LVNC were graded using a validated, semi-quantitative system based on all published genetic and experimental evidence created by the Clinical Genome Resource (ClinGen). Genetic pathway analysis identified molecular processes and pathways associated with LVNC.

RESULTS

We identified 189 genes associated with LVNC: 11 (6%) were classified as definitive, 21 (11%) were classified as moderate, and 140 (74%) were classified as limited, but 17 (9%) were classified as no evidence. Of the 32 genes classified as definitive or moderate, the most common gene functions were sarcomere function (n=11; 34%), transcriptional/translational regulator (n=6; 19%), mitochondrial function (n=3; 9%), and cytoskeletal protein (n=3; 9%). Furthermore, 18 (56%) genes were implicated in noncardiac syndromic presentations. Lastly, 3 genetic pathways (cardiomyocyte differentiation via BMP receptors, factors promoting cardiogenesis in vertebrates, and Notch signaling) were found to be unique to LVNC and not overlap with pathways identified in dilated cardiomyopathy and hypertrophic cardiomyopathy.

CONCLUSIONS

LVNC is a genetically heterogeneous cardiomyopathy. Distinct from dilated or hypertrophic cardiomyopathies, LVNC appears to arise from abnormal developmental processes.

PHACTR-1 (Phosphatase and Actin Regulator 1) Deficiency in Either Endothelial or Smooth Muscle Cells Does Not Predispose Mice to Nonatherosclerotic Arteriopathies in 3 Transgenic Mice

BACKGROUND

Genome-wide association studies have revealed robust associations of common genetic polymorphisms in an intron of the PHACTR-1 (phosphatase and actin regulator 1) gene (chr6p24), with cervical artery dissection, spontaneous coronary artery dissection, and fibromuscular dysplasia. The aim was to assess its role in the pathogenesis of cervical artery dissection or fibromuscular dysplasia.

METHODS

Using various tissue-specific Cre-driver mouse lines, Phactr1 was deleted either in endothelial cells using 2 tissue-specific Cre-driver (PDGFB [platelet-derived growth factor B]-Cre^ERT2 mice and Tie2 [tyrosine kinase with immunoglobulin and EGF homology domains]-Cre) and smooth muscle cells (smooth muscle actin-Cre^ERT2) with a third tissue-specific Cre-driver.

RESULTS

To test the efficacy of the Phactr1 deletion after cre-induction, we confirmed first, a decrease in Phactr1 transcription and Phactr1 expression in endothelial cell and smooth muscle cell isolated from Phactr1^iPDGFB and Phactr1^iSMA mice. Irrespective to the tissue or the duration of the deletion, mice did not spontaneously display pathological phenotype or vascular impairment: mouse survival, growth, blood pressure, large vessel morphology, or actin organization were not different in knockout mice than their comparatives littermates. Challenging vascular function and repair either by angiotensin II-induced hypertension or limb ischemia did not lead to vascular morphology or function impairment in Phactr1-deleted mice. Similarly, there were no more consequences of Phactr1 deletion during embryogenesis in endothelial cells.

CONCLUSIONS

Loss of PHACTR-1 function in the cells involved in vascular physiology does not appear to induce a pathological vascular phenotype. The in vivo effect of the intronic variation described in genome-wide association studies is unlikely to involve downregulation in PHACTR-1 expression.

Comparison of Large Animal Models for Acute Ischemic Stroke: Which Model to Use?

Translation of acute ischemic stroke research to the clinical setting remains limited over the last few decades with only one drug, recombinant tissue-type plasminogen activator, successfully completing the path from experimental study to clinical practice. To improve the selection of experimental treatments before testing in clinical studies, the use of large gyrencephalic animal models of acute ischemic stroke has been recommended. Currently, these models include, among others, dogs, swine, sheep, and nonhuman primates that closely emulate aspects of the human setting of brain ischemia and reperfusion. Species-specific characteristics, such as the cerebrovascular architecture or pathophysiology of thrombotic/ischemic processes, significantly influence the suitability of a model to address specific research questions. In this article, we review key characteristics of the main large animal models used in translational studies of acute ischemic stroke, regarding (1) anatomy and physiology of the cerebral vasculature, including brain morphology, coagulation characteristics, and immune function; (2) ischemic stroke modeling, including vessel occlusion approaches, reproducibility of infarct size, procedural complications, and functional outcome assessment; and (3) implementation aspects, including ethics, logistics, and costs. This review specifically aims to facilitate the selection of the appropriate large animal model for studies on acute ischemic stroke, based on specific research questions and large animal model characteristics.

Changes in inferior vena cava area represent a more sensitive metric than change in filling pressures during experimental manipulation of intravascular volume and tone

Aims

Remote monitoring of pulmonary artery pressure has reduced heart failure (HF) hospitalizations in chronic HF as elevation of pulmonary artery pressure provides information that can guide treatment. The venous system is characterized by high capacitance, thus substantial increases in intravascular volume can occur before filling pressures increase. The inferior vena cava (IVC) is a highly compliant venous conduit and thus a candidate for early detection of change in intravascular volume. We aimed to compare IVC cross‐sectional area using a novel sensor with cardiac filling pressures during experimental manipulation of volume status, vascular tone, and cardiac function.

Methods and results

Experiments were conducted in sheep to manipulate volume status (colloid infusion), vascular tone (nitroglycerin infusion) and cardiac function (rapid cardiac pacing). A wireless implantable IVC sensor was validated ex‐vivo and in‐vivo, and then used to measure the cross‐sectional area of the IVC. Right‐ and left‐sided cardiac filling pressures were obtained via right heart catheterization. The IVC sensor provided highly accurate and precise measurements of cross‐sectional area in ex‐vivo and in‐vivo validation. IVC area changes were more sensitive than the corresponding changes in cardiac filling pressures during colloid infusion (p < 0.001), vasodilatation (p < 0.001) and cardiac dysfunction induced by rapid pacing (p ≤ 0.02).

Conclusions

Inferior vena cava area can be remotely and accurately measured in real time with a wireless implantable sensor. Changes in IVC area are more sensitive than corresponding changes in filling pressures following experimental volume loading and fluid redistribution. Additional research is warranted to understand if remote monitoring of the IVC may have advantages over pressure‐based monitors in HF.

FGF-23 (Fibroblast Growth Factor-23) and Cardiorenal Interactions

BACKGROUND

Animal models implicate FGF-23 (fibroblast growth factor-23) as a direct contributor to adverse cardiorenal interactions such as sodium avidity, diuretic resistance, and neurohormonal activation, but this has not been conclusively demonstrated in humans. Therefore, we aimed to evaluate whether FGF-23 is associated with parameters of cardiorenal dysfunction in humans with heart failure, independent of confounding factors.

METHODS

One hundred ninety-nine outpatients with heart failure undergoing diuretic treatment at the Yale Transitional Care Center were enrolled and underwent blood collection, and urine sampling before and after diuretics.

RESULTS

FGF-23 was associated with several metrics of disease severity such as higher home loop diuretic dose and NT-proBNP (N-terminal pro-B-type natriuretic peptide), and lower estimated glomerular filtration rate, serum chloride, and serum albumin. Multivariable analysis demonstrated no statistically significant association between FGF-23 and sodium avidity measured by fractional excretion of sodium, or proximal or distal tubular sodium reabsorption, either before diuretic administration or at peak diuresis (P≥0.11 for all). Likewise, FGF-23 was not independently associated with parameters of diuretic resistance (diuretic excretion, cumulative urine and sodium output, and loop diuretic efficiency [P≥0.33 for all]) or neurohormonal activation (plasma or urine renin [P≥0.36 for all]). Moreover, the upper boundary of the 95% CI of all the partial correlations were ≤0.30, supporting the lack of meaningful correlations. FGF-23 was not associated with mortality in multivariable analysis (P=0.44).

CONCLUSIONS

FGF-23 was not meaningfully associated with any cardiorenal parameter in patients with heart failure. While our methods cannot rule out a small effect, FGF-23 is unlikely to be a primary driver of cardiorenal interactions.

Analysis of 18F-Sodium Fluoride Positron Emission Tomography Signal Sources in Atherosclerotic Minipigs Shows Specific Binding of 18F-Sodium Fluoride to Plaque Calcifications

OBJECTIVE

¹⁸F-sodium fluoride (¹⁸F-NaF) positron emission tomography (PET) imaging is thought to visualize active atherosclerotic plaque calcification. This is supported by the binding of ¹⁸F-NaF to plaque calcification ex vivo, but no prior studies have examined binding of ¹⁸F-NaF to human-like plaque in vivo. Our aim was to validate the specificity of ¹⁸F-NaF PET for plaque calcifications in atherosclerotic minipigs. Approach and Results: Gain-of-function PCSK9^D374Y (proprotein convertase/subtilisin kexin type 9) transgenic Yucatan minipigs (n=4) were fed high-fat diet for 2.5 years to develop atherosclerosis and then subjected to ¹⁸F-NaF PET/computed tomography imaging. The heart, aorta, and iliac arteries were immediately re-scanned ex vivo after surgical extraction. Lesions from the abdominal aorta, iliac arteries, and coronary arteries were cryo-sectioned for autoradiography. Histological plaque characteristics, PET/computed tomography signal, and autoradiography were linked through regression and co-localization analysis. Arterial ¹⁸F-NaF PET signal had intensities comparable to clinical scans and colocalized moderately with calcification detected by computed tomography. Histological analysis showed calcification spanning from microcalcifications near lipid pools and necrotic core to more homogenous macrocalcifications. Comparison with arteries from autopsy cases confirmed the resemblance in localization and appearance with early human plaque calcification. Regression analysis in the abdominal aorta showed correlations with calcified plaque but could not rule out contributions from noncalcified plaque. This was resolved by autoradiography, which showed specific accumulation in plaque calcifications in all examined arteries. In the context of porcine abdominal aorta, ¹⁸F-NaF PET imaging was, however, less accurate than computed tomography for detecting small calcifications.

CONCLUSIONS

¹⁸F-NaF accumulates specifically in calcifications of atherosclerotic plaques in vivo.

Patterns of Neointima Formation After Coil or Stent Treatment in a Rat Saccular Sidewall Aneurysm Model

BACKGROUND AND PURPOSE

Endovascular aneurysm treatment relies on a biological process, including cell migration for thrombus organization and growth of a neointima. To better understand aneurysm healing, our study explores the origin of neointima-forming and thrombus-organizing cells in a rat saccular sidewall aneurysm model.

METHODS

Saccular aneurysms were transplanted onto the abdominal aorta of male Lewis rats and endovascularly treated with coils (n=28) or stents (n=26). In 34 cases, GFP+ (green fluorescent protein)-expressing vital aneurysms were sutured on wild-type rats, and in 23 cases, decellularized wild-type aneurysms were sutured on GFP+ rats. Follow-up at 3, 7, 14, 21, and 28 days evaluated aneurysms by fluorescence angiography, macroscopic inspection, and microscopy for healing and inflammation status. Furthermore, the origin of cells was tracked with fluorescence histology.

RESULTS

In animals with successful functional healing, histological studies showed a gradually advancing thrombus organization over time characterized by progressively growing neointima from the periphery of the aneurysm toward the center. Cell counts revealed similar distributions of GFP+ cells for coil or stent treatment in the aneurysm wall (54.4% versus 48.7%) and inside the thrombus (20.5% versus 20.2%) but significantly more GFP+ cells in the neointima of coiled (27.2 %) than stented aneurysms (10.4%; P=0.008).

CONCLUSIONS

Neointima formation and thrombus organization are concurrent processes during aneurysm healing. Thrombus-organizing cells originate predominantly in the parent artery. Neointima formation relies more on cell migration from the aneurysm wall in coiled aneurysms but receives greater contributions from cells originating in the parent artery in stent-treated aneurysms. Cell migration, which allows for a continuous endothelial lining along the parent artery's lumen, may be a prerequisite for complete aneurysm healing after endovascular therapy. In terms of translation into clinical practice, these findings may explain the variability in achieving complete aneurysm healing after coil treatment and the improved healing rate in stent-assisted coiling.

High NOR-1 (Neuron-Derived Orphan Receptor 1) Expression Strengthens the Vascular Wall Response to Angiotensin II Leading to Aneurysm Formation in Mice

No drug therapy has shown to limit abdominal aortic aneurysm (AAA) growth or rupture, and the understanding of the disease biology is incomplete; whereby, one challenge of vascular medicine is the development of good animal models and therapies for this life-threatening condition. The nuclear receptor NOR-1 (neuron-derived orphan receptor 1) controls biological processes involved in AAA; however, whether it plays a role in this pathology is unknown. Through a gain-of-function approach we assessed the impact of NOR-1 expression on the vascular response to Ang II (angiotensin II). We used 2 mouse models that overexpress human NOR-1 in the vasculature, one of them specifically in vascular smooth muscle cells. NOR-1 transgenesis amplifies the response to Ang II enhancing vascular inflammation (production of proinflammatory cytokines, chemokines, and reactive oxygen species), increasing MMP (matrix metalloproteinase) activity and disturbing elastin integrity, thereby broking the resistance of C57BL/6 mice to Ang II-induced AAA. Genes encoding for proteins critically involved in AAA formation (Il [interleukin]-6, Il-1β, Cxcl2, [C-X-C motif chemokine ligand 2], Mcp-1 [monocyte chemoattractant protein 1], and Mmp2) were upregulated in aneurysmal tissues. Both animal models show a similar incidence and severity of AAA, suggesting that high expression of NOR-1 in vascular smooth muscle cell is a sufficient condition to strengthen the response to Ang II. These alterations, including AAA formation, were prevented by the MMP inhibitor doxycycline. Microarray analysis identified gene sets that could explain the susceptibility of transgenic animals to Ang II-induced aneurysms, including those related with extracellular matrix remodeling, inflammatory/immune response, sympathetic activity, and vascular smooth muscle cell differentiation. These results involve NOR-1 in AAA and validate mice overexpressing this receptor as useful experimental models.

Altered Macrophage Polarization Induces Experimental Pulmonary Hypertension and Is Observed in Patients With Pulmonary Arterial Hypertension

Supplemental Digital Content is available in the text.

To determine whether global reduction of CD68 (cluster of differentiation) macrophages impacts the development of experimental pulmonary arterial hypertension (PAH) and whether this reduction affects the balance of pro- and anti-inflammatory macrophages within the lung. Additionally, to determine whether there is evidence of an altered macrophage polarization in patients with PAH.

Effect of Dietary Sodium Modulation on Pig Adrenal Steroidogenesis and Transcriptome Profiles

Primary aldosteronism is a frequent form of endocrine hypertension caused by aldosterone overproduction from the adrenal cortex. Regulation of aldosterone biosynthesis has been studied in rodents despite differences in adrenal physiology with humans. We, therefore, investigated pig adrenal steroidogenesis, morphology, and transcriptome profiles of the zona glomerulosa (zG) and zona fasciculata in response to activation of the renin-angiotensin-aldosterone system by dietary sodium restriction. Six-week-old pigs were fed a low- or high-sodium diet for 14 days (3 pigs per group, 0.4 g sodium/kg feed versus 6.8 g sodium/kg). Plasma aldosterone concentrations displayed a 43-fold increase (P=0.011) after 14 days of sodium restriction (day 14 versus day 0). Low dietary sodium caused a 2-fold increase in thickness of the zG (P<0.001) and an almost 3-fold upregulation of CYP11B (P<0.05) compared with high dietary sodium. Strong immunostaining of the KCNJ5 (G protein-activated inward rectifier potassium channel 4), which is frequently mutated in primary aldosteronism, was demonstrated in the zG. mRNA sequencing transcriptome analysis identified significantly altered expression of genes modulated by the renin-angiotensin-aldosterone system in the zG (n=1172) and zona fasciculata (n=280). These genes included many with a known role in the regulation of aldosterone synthesis and adrenal function. The most highly enriched biological pathways in the zG were related to cholesterol biosynthesis, steroid metabolism, cell cycle, and potassium channels. This study provides mechanistic insights into the physiology and pathophysiology of aldosterone production in a species closely related to humans and shows the suitability of pigs as a translational animal model for human adrenal steroidogenesis.

Sex and Genetic Background Effects on the Outcome of Experimental Intracranial Aneurysms

BACKGROUND AND PURPOSE

Intracranial aneurysm formation and rupture risk are, in part, determined by genetic factors and sex. To examine their role, we compared 3 mouse strains commonly used in cerebrovascular studies in a model of intracranial aneurysm formation and rupture.

METHODS

Intracranial aneurysms were induced in male CD1 (Crl:CD1[ICR]), male and female C57 (C57BL/6NCrl), and male 129Sv (129S2/SvPasCrl or 129S1/SvImJ) mice by stereotaxic injection of elastase at the skull base, combined with systemic deoxycorticosterone acetate-salt hypertension. Neurological deficits and mortality were recorded. Aneurysms and subarachnoid hemorrhage grades were quantified postmortem, either after spontaneous mortality or at 7 to 21 days if the animals survived. In separate cohorts, we examined proinflammatory mediators by quantitative reverse transcriptase-polymerase chain reaction, arterial blood pressure via the femoral artery, and the circle of Willis by intravascular latex casting.

RESULTS

We found striking differences in aneurysm formation, rupture, and postrupture survival rates among the groups. 129Sv mice showed the highest rates of aneurysm rupture (80%), followed by C57 female (36%), C57 male (27%), and CD1 (21%). The risk of aneurysm rupture and the presence of unruptured aneurysms significantly differed among all 3 strains, as well as between male and female C57. The same hierarchy was observed upon Kaplan-Meier analysis of both overall survival and deficit-free survival. Subarachnoid hemorrhage grades were also more severe in 129Sv. CD1 mice showed the highest resistance to aneurysm rupture and the mildest outcomes. Higher mean blood pressures and the major phenotypic difference in the circle of Willis anatomy in 129Sv provided an explanation for the higher incidence of and more severe aneurysm ruptures. TNFα (tumor necrosis factor-alpha), IL-1β (interleukin-1-beta), and CCL2 (chemokine C-C motif ligand 2) expressions did not differ among the groups.

CONCLUSIONS

The outcome of elastase-induced intracranial aneurysm formation and rupture in mice depends on genetic background and shows sexual dimorphism.

HDL (High-Density Lipoprotein) Remodeling and Magnetic Resonance Imaging-Assessed Atherosclerotic Plaque Burden: Study in a Preclinical Experimental Model

OBJECTIVE

HDL (high-density lipoprotein) role in atherosclerosis is controversial. Clinical trials with CETP (cholesterylester transfer protein)-inhibitors have not provided benefit. We have shown that HDL remodeling in hypercholesterolemia reduces HDL cardioprotective potential. We aimed to assess whether hypercholesterolemia affects HDL-induced atherosclerotic plaque regression. Approach and Results: Atherosclerosis was induced in New Zealand White rabbits for 3-months by combining a high-fat-diet and double-balloon aortic denudation. Then, animals underwent magnetic resonance imaging (basal plaque) and randomized to receive 4 IV infusions (1 infusion/wk) of HDL isolated from normocholesterolemic (NC-HDL; 75 mg/kg; n=10), hypercholesterolemic (HC-HDL; 75 mg/Kg; n=10), or vehicle (n=10) rabbits. Then, animals underwent a second magnetic resonance imaging (end plaque). Blood, aorta, and liver samples were obtained for analyses. Follow-up magnetic resonance imaging revealed that NC-HDL administration regressed atherosclerotic lesions by 4.3%, whereas, conversely, the administration of HC-HDLs induced a further 6.5% progression (P<0.05 versus basal). Plaque characterization showed that HC-HDL administered animals had a 2-fold higher lipid and cholesterol content versus those infused NC-HDL and vehicle (P<0.05). No differences were observed among groups in CD31 levels, nor in infiltrated macrophages or smooth muscle cells. Plaques from HC-HDL administered animals exhibited higher Casp3 (caspase 3) content (P<0.05 versus vehicle and NC-HDL) whereas plaques from NC-HDL infused animals showed lower expression of Casp3, Cox1 (cyclooxygenase 1), inducible nitric oxide synthase, and MMP (metalloproteinase) activity (P<0.05 versus HC-HDL and vehicle). HDLs isolated from animals administered HC-HDL displayed lower antioxidant potential and cholesterol efflux capacity as compared with HDLs isolated from NC-HDL-infused animal and vehicle or donor HDL (P<0.05). There were no differences in HDL-ApoA1 content, ABCA1 (ATP-binding cassette transporter A1) vascular expression, and SRB1 (scavenger receptor B1) and ABCA1 liver expression.

CONCLUSIONS

HDL particles isolated from a hypercholesterolemic milieu lose their ability to regress and stabilize atherosclerotic lesions. Our data suggest that HDL remodeling in patients with co-morbidities may lead to the loss of HDL atheroprotective functions.

Somatic Gain of KRAS Function in the Endothelium Is Sufficient to Cause Vascular Malformations That Require MEK but Not PI3K Signaling

Supplemental Digital Content is available in the text.

Rationale:

We previously identified somatic activating mutations in the KRAS (Kirsten rat sarcoma viral oncogene homologue) gene in the endothelium of the majority of human sporadic brain arteriovenous malformations; a disorder characterized by direct connections between arteries and veins. However, whether this genetic abnormality alone is sufficient for lesion formation, as well as how active KRAS signaling contributes to arteriovenous malformations, remains unknown.

Objective:

To establish the first in vivo models of somatic KRAS gain of function in the endothelium in both mice and zebrafish to directly observe the phenotypic consequences of constitutive KRAS activity at a cellular level in vivo, and to test potential therapeutic interventions for arteriovenous malformations.

Methods and Results:

Using both postnatal and adult mice, as well as embryonic zebrafish, we demonstrate that endothelial-specific gain of function mutations in Kras (G12D or G12V) are sufficient to induce brain arteriovenous malformations. Active KRAS signaling leads to altered endothelial cell morphogenesis and increased cell size, ectopic sprouting, expanded vessel lumen diameter, and direct connections between arteries and veins. Furthermore, we show that these lesions are not associated with altered endothelial growth dynamics or a lack of proper arteriovenous identity but instead seem to feature exuberant angiogenic signaling. Finally, we demonstrate that KRAS-dependent arteriovenous malformations in zebrafish are refractory to inhibition of the downstream effector PI3K but instead require active MEK (mitogen-activated protein kinase kinase 1) signaling.

Conclusions:

We demonstrate that active KRAS expression in the endothelium is sufficient for brain arteriovenous malformations, even in the setting of uninjured adult vasculature. Furthermore, the finding that KRAS-dependent lesions are reversible in zebrafish suggests that MEK inhibition may represent a promising therapeutic treatment for arteriovenous malformation patients.

Environment-Sensing Aryl Hydrocarbon Receptor Inhibits the Chondrogenic Fate of Modulated Smooth Muscle Cells in Atherosclerotic Lesions

BACKGROUND

Smooth muscle cells (SMC) play a critical role in atherosclerosis. The Aryl hydrocarbon receptor (AHR) is an environment-sensing transcription factor that contributes to vascular development, and has been implicated in coronary artery disease risk. We hypothesized that AHR can affect atherosclerosis by regulating phenotypic modulation of SMC.

METHODS

We combined RNA-sequencing, chromatin immunoprecipitation followed by sequencing, assay for transposase-accessible chromatin using sequencing, and in vitro assays in human coronary artery SMCs, with single-cell RNA-sequencing, histology, and RNAscope in an SMC-specific lineage-tracing Ahr knockout mouse model of atherosclerosis to better understand the role of AHR in vascular disease.

RESULTS

Genomic studies coupled with functional assays in cultured human coronary artery SMCs revealed that AHR modulates the human coronary artery SMC phenotype and suppresses ossification in these cells. Lineage-tracing and activity-tracing studies in the mouse aortic sinus showed that the Ahr pathway is active in modulated SMCs in the atherosclerotic lesion cap. Furthermore, single-cell RNA-sequencing studies of the SMC-specific Ahr knockout mice showed a significant increase in the proportion of modulated SMCs expressing chondrocyte markers such as Col2a1 and Alpl, which localized to the lesion neointima. These cells, which we term "chondromyocytes," were also identified in the neointima of human coronary arteries. In histological analyses, these changes manifested as larger lesion size, increased lineage-traced SMC participation in the lesion, decreased lineage-traced SMCs in the lesion cap, and increased alkaline phosphatase activity in lesions in the Ahr knockout in comparison with wild-type mice. We propose that AHR is likely protective based on these data and inference from human genetic analyses.

CONCLUSIONS

Overall, we conclude that AHR promotes the maintenance of lesion cap integrity and diminishes the disease-related SMC-to-chondromyocyte transition in atherosclerotic tissues.

Icariin Promotes Fracture Healing in Ovariectomized Rats

BACKGROUND Osteoporotic fractures are common in postmenopausal women and associated with complications. Numerous studies have demonstrated that icariin can be used to treat fractures and osteoporosis. Herein, we evaluated the efficacy of gavage-administered icariin to promote fracture healing in postmenopausal osteoporotic fracture (POF) rats. MATERIAL AND METHODS In this study, ovariectomy-induced POF rats were treated with 600 mg/kg icariin. Micro-computed tomography (micro-CT) was used to assess fracture healing; besides, serum APK, TRACP-5b, and E₂ expression levels were detected by commercial kits, and the uterine index was calculated. In addition, the expression of osteogenesis-related proteins (Runx 2 and COL1A2) in the callus was measured by western blot, whereas the expression of OPG/RANKL pathway proteins was measured by western blot and immunohistochemical analysis. RESULTS Our data revealed that icariin promoted the expression level of Runx 2 and COL1A2 and suppressed the expression level of serum bone turn over biomarkers via the OPG/RANKL pathway. Besides, a more mature callus was observed in the POF rats receiving icariin than in the untreated POF rats, while serum E₂ and uterine index were unaffected by icariin treatment. CONCLUSIONS These results revealed that icariin could promote fracture healing in ovariectomized rats via OPG/RANKL signaling, and that serum E₂ and uterine index were not affected by icariin treatment.

Novel Chronic Mouse Model of Cerebral Cavernous Malformations

Background and Purpose- Cerebral cavernous malformations (CCMs) are vascular malformations of the brain that lead to cerebral hemorrhages. A pharmacological treatment is needed especially for patients with nonoperable deep-seated lesions. We and others obtained CCM mouse models that were useful for mechanistic studies and rapid trials testing the preventive effects of candidate drugs. The shortened lifespan of acute mouse models hampered evaluation of compounds that would not only prevent lesion appearance but also cure preexisting lesions. Indirubin-3'-monoxime previously demonstrated its efficacy to reverse the cardiac phenotype of ccm2^m201 zebrafish mutants and to prevent lesion development in an acute CCM2 mouse model. In the present article, we developed and characterized a novel chronic CCM2 mouse model and evaluated the curative therapeutic effect of indirubin-3'-monoxime after CCM lesion development. Methods- The chronic mouse model was obtained by a postnatal induction of brain-endothelial-cell-specific ablation of the Ccm2 gene using the inducible Slco1c1-CreER^T2 mouse line. Results- We obtained a fully penetrant novel CCM chronic mouse model without any obvious off-target phenotypes and compatible with long-term survival. By 3 months of age, CCM lesions ranging in size from small isolated lesions to multiple caverns developed throughout the brain. Lesion burden was quantified in animals from 1 week to 5 months of age. Clear signs of intracerebral hemorrhages were noticed in brain-endothelial-cell-specific ablation of the Ccm2 gene. In contrast with its preventive effect in the acute CCM2 mouse model, a 20 mg/kg indirubin-3'-monoxime treatment for 3 weeks in 3-month old animals neither had any beneficial effect on the lesion burden nor alleviated cerebral hemorrhages. Conclusions- The brain-endothelial-cell-specific ablation of the Ccm2 gene chronic model is a strongly improved disease model for the CCM community whose challenge today is to decipher which candidate drugs might have a curative effect on patients' preexisting lesions. Visual Overview- An online visual overview is available for this article.

Deleting Full Length Titin Versus the Titin M-Band Region Leads to Differential Mechanosignaling and Cardiac Phenotypes

BACKGROUND

Titin is a giant elastic protein that spans the half-sarcomere from Z-disk to M-band. It acts as a molecular spring and mechanosensor and has been linked to striated muscle disease. The pathways that govern titin-dependent cardiac growth and contribute to disease are diverse and difficult to dissect.

METHODS

To study titin deficiency versus dysfunction, the authors generated and compared striated muscle specific knockouts (KOs) with progressive postnatal loss of the complete titin protein by removing exon 2 (E2-KO) or an M-band truncation that eliminates proper sarcomeric integration, but retains all other functional domains (M-band exon 1/2 [M1/2]-KO). The authors evaluated cardiac function, cardiomyocyte mechanics, and the molecular basis of the phenotype.

RESULTS

Skeletal muscle atrophy with reduced strength, severe sarcomere disassembly, and lethality from 2 weeks of age were shared between the models. Cardiac phenotypes differed considerably: loss of titin leads to dilated cardiomyopathy with combined systolic and diastolic dysfunction-the absence of M-band titin to cardiac atrophy and preserved function. The elastic properties of M1/2-KO cardiomyocytes are maintained, while passive stiffness is reduced in the E2-KO. In both KOs, we find an increased stress response and increased expression of proteins linked to titin-based mechanotransduction (CryAB, ANKRD1, muscle LIM protein, FHLs, p42, Camk2d, p62, and Nbr1). Among them, FHL2 and the M-band signaling proteins p62 and Nbr1 are exclusively upregulated in the E2-KO, suggesting a role in the differential pathology of titin truncation versus deficiency of the full-length protein. The differential stress response is consistent with truncated titin contributing to the mechanical properties in M1/2-KOs, while low titin levels in E2-KOs lead to reduced titin-based stiffness and increased strain on the remaining titin molecules.

CONCLUSIONS

Progressive depletion of titin leads to sarcomere disassembly and atrophy in striated muscle. In the complete knockout, remaining titin molecules experience increased strain, resulting in mechanically induced trophic signaling and eventually dilated cardiomyopathy. The truncated titin in M1/2-KO helps maintain the passive properties and thus reduces mechanically induced signaling. Together, these findings contribute to the molecular understanding of why titin mutations differentially affect cardiac growth and have implications for genotype-phenotype relations that support a personalized medicine approach to the diverse titinopathies.

Chloroquine Treatment Suppresses Mucosal Inflammation in a Mouse Model of Eosinophilic Chronic Rhinosinusitis

PURPOSE

The Toll-like receptor 9 (TLR9) signaling pathway is involved in the pathogenesis of chronic rhinosinusitis (CRS) with nasal polyposis. The aim of this study was to assess the therapeutic potential of the TLR9 pathway inhibitor chloroquine in CRS mice.

METHODS

The expression of type I interferons (IFNs) in human CRS tissues was evaluated using quantitative polymerase chain reaction (qPCR), western blotting, and immunofluorescence. Mice were divided into 4 treatment groups: the control, nasal polyp (NP), chloroquine treatment (NP + Chlq), and dexamethasone treatment (NP + Dexa) groups. The effects of chloroquine on polyp formation and mucosal inflammation were examined by hematoxylin and eosin staining. The expression levels of type I IFN, B-cell activating factor (BAFF), TLR9, high mobility group box 1 (HMGB1), and proinflammatory cytokine expression levels were assessed using qPCR, western blot, or enzyme-linked immunosorbent assay.

RESULTS

IFN-α and IFN-β mRNA levels were significantly higher in patients with eosinophilic NPs (EPs) than in healthy individuals or non-EP patients. The polyp score, epithelial thickness, mucosal thickness, and the number of eosinophils in nasal mucosa were significantly higher in the NP group compared with the control, NP + Chlq, and NP + Dexa groups. NP + Chlq or NP + Dexa significantly suppressed the induction of type I IFN and BAFF expression in the NP group; these treatments also significantly suppressed the induction of TLR9, HMGB1, interferon regulatory factors, interleukin (IL)-6, IL-1β, tumor necrosis factor-α, and Th cytokine expression in the NP group. The secreted levels of anti-dsDNA Immunoglobulin G (IgG) were significantly higher in the NP group than in the control, NP + Chlq, and NP + Dexa groups. There were significant positive correlations between BAFF and mRNA levels of IFN-α/β/the protein levels of anti-dsDNA IgG.

CONCLUSIONS

Chloroquine may be used for the treatment of patients with eosinophilic CRS.

Cellular Mechanisms of Aortic Aneurysm Formation

Aortic aneurysms are a common vascular disease in Western populations that can involve virtually any portion of the aorta. Abdominal aortic aneurysms are much more common than thoracic aortic aneurysms and combined they account for >25 000 deaths in the United States annually. Although thoracic and abdominal aortic aneurysms share some common characteristics, including the gross anatomic appearance, alterations in extracellular matrix, and loss of smooth muscle cells, they are distinct diseases. In recent years, advances in genetic analysis, robust molecular tools, and increased availability of animal models have greatly enhanced our knowledge of the pathophysiology of aortic aneurysms. This review examines the various proposed cellular mechanisms responsible for aortic aneurysm formation and identifies opportunities for future studies.

Roles of Coagulation Proteases and PARs (Protease-Activated Receptors) in Mouse Models of Inflammatory Diseases

Activation of the blood coagulation cascade leads to fibrin deposition and platelet activation that are required for hemostasis. However, aberrant activation of coagulation can lead to thrombosis. Thrombi can cause tissue ischemia, and fibrin degradation products and activated platelets can enhance inflammation. In addition, coagulation proteases activate cells by cleavage of PARs (protease-activated receptors), including PAR1 and PAR2. Direct oral anticoagulants have recently been developed to specifically inhibit the coagulation proteases FXa (factor Xa) and thrombin. Administration of these inhibitors to wild-type mice can be used to determine the roles of FXa and thrombin in different inflammatory diseases. These results can be compared with the phenotypes of mice with deficiencies of either Par1 (F2r) or Par2 (F2rl1). However, inhibition of coagulation proteases will have effects beyond reducing PAR signaling, and a deficiency of PARs will abolish signaling from all proteases that activate these receptors. We will summarize studies that examine the roles of coagulation proteases, particularly FXa and thrombin, and PARs in different mouse models of inflammatory disease. Targeting FXa and thrombin or PARs may reduce inflammatory diseases in humans.

Animal Models of Hypertension: A Scientific Statement From the American Heart Association

Hypertension is the most common chronic disease in the world, yet the precise cause of elevated blood pressure often cannot be determined. Animal models have been useful for unraveling the pathogenesis of hypertension and for testing novel therapeutic strategies. The utility of animal models for improving the understanding of the pathogenesis, prevention, and treatment of hypertension and its comorbidities depends on their validity for representing human forms of hypertension, including responses to therapy, and on the quality of studies in those models (such as reproducibility and experimental design). Important unmet needs in this field include the development of models that mimic the discrete hypertensive syndromes that now populate the clinic, resolution of ongoing controversies in the pathogenesis of hypertension, and the development of new avenues for preventing and treating hypertension and its complications. Animal models may indeed be useful for addressing these unmet needs.

Treatment of Pulmonary Hypertension With Angiotensin II Receptor Blocker and Neprilysin Inhibitor Sacubitril/Valsartan

BACKGROUND

Angiotensin II has been implicated in maladaptive right ventricular (RV) hypertrophy and fibrosis associated with pulmonary hypertension (PH). Natriuretic peptides decrease RV afterload by promoting pulmonary vasodilation and inhibiting vascular remodeling but are degraded by neprilysin. We hypothesized that angiotensin receptor blocker and neprilysin inhibitor, sacubitril/valsartan (Sac/Val, LCZ696), will attenuate PH and improve RV function by targeting both pulmonary vascular and RV remodeling.

METHODS

PH was induced in rats using the SU5416/hypoxia model (Su/Hx), followed by 6-week treatment with placebo, Sac/Val, or Val alone. There were 4 groups: CON-normoxic animals with placebo (n=18); PH-Su/Hx rats+placebo (n=34); PH+Sac/Val (N=24); and PH+Val (n=16).

RESULTS

In animals with PH, treatment with Sac/Val but not Val resulted in significant reduction in RV pressure (mm Hg: PH: 62±4, PH+Sac/Val: 46±5), hypertrophy (RV/LV+S: PH: 0.74±0.06, PH+Sac/Val: 0.46±0.06), collagen content (µg/50 µg protein: PH: 8.2±0.3, PH+Sac/Val: 6.4±0.4), pressures and improvement in RVs (mm/s: PH: 31.2±1.8, PH+Sac/Val: 43.1±3.6) compared with placebo. This was associated with reduced pulmonary vascular wall thickness, increased lung levels of ANP (atrial natriuretic peptide), BNP (brain-type natriuretic peptide), and cGMP, and decreased plasma endothelin-1 compared with PH alone. Also, PH+Sac/Val animals had altered expression of PKC isozymes in RV tissue compared with PH alone.

CONCLUSIONS

Sac/Val reduces pulmonary pressures, vascular remodeling, as well as RV hypertrophy in a rat model of PH and may be appropriate for treatment of pulmonary hypertension and RV dysfunction.

Effect of Intracoronary Metformin on Myocardial Infarct Size in Swine

RATIONALE

Metformin has been demonstrated to decrease infarct size (IS) and prevent postinfarction left ventricular (LV) remodeling in rodents when given intravenously at the time of reperfusion. It remains unclear whether similar cardioprotection can be achieved in a large animal model.

OBJECTIVE

The objective of this study was to determine whether intravascular infusion of metformin at the time of reperfusion reduces myocardial IS in a porcine model of acute myocardial infarction.

METHODS AND RESULTS

In a blinded and randomized preclinical study, closed-chest swine (n=20) were subjected to a 60-minute left anterior descending coronary artery occlusion to produce myocardial infarction. Contrast-enhanced computed tomography was performed during left anterior descending coronary artery occlusion to assess the ischemic area-at-risk. Animals were randomized to receive either metformin or vehicle as an initial intravenous bolus (5 mg/kg) 8 minutes before reperfusion, followed by a 15-minute left coronary artery infusion (1 mg/kg per minute) commencing with the onset of reperfusion. Echocardiography and computed tomographic imaging of LV function were performed 1 week later, at which time the heart was removed for postmortem pathological analysis of area-at-risk and IS (triphenyltetrazolium chloride). Baseline variables including hemodynamics and LV function were similar between groups. Peak circulating metformin concentrations of 374±35 µmol/L were achieved 15 minutes after reperfusion. There was no difference between the area-at-risk as a percent of LV mass by computed tomography (vehicle: 20.7%±1.1% versus metformin: 19.7%±1.3%; P=0.59) or postmortem pathology (22.4%±1.2% versus 20.2%±1.2%; P=0.21). IS relative to area-at-risk averaged 44.5%±5.0% in vehicle-treated versus 38.2%±6.8% in metformin-treated animals ( P=0.46). There was no difference in global function 7 days after myocardial infarction as assessed by echocardiography or computed tomographic ejection fraction (56.2%±2.6% versus 56.3%±2.4%; P=0.98).

CONCLUSIONS

In contrast to rodent hearts, postconditioning with high-dose metformin administered immediately before reperfusion does not reduce IS or improve LV function 7 days after myocardial infarction in swine. These results reinforce the importance of rigorously testing therapies in large animal models to facilitate clinical translation of novel cardioprotective therapies.