Gene expression differences during the heterogeneous progression of peripheral atherosclerosis in familial hypercholesterolemic swine

Revelation of genetic diversity and genomic footprints of adaptation in Indian pig breeds

In the present study, the genetic diversity measures among four Indian domestic breeds of pig namely Agonda Goan, Ghurrah, Ghungroo, and Nicobari, of different agro-climatic regions of country were explored and compared with European commercial breeds, European wild boar and Chinese domestic breeds. The double digest restriction site-associated DNA sequencing (ddRADseq) data of Indian pigs (102) and Landrace (10 animals) were generated and whole genome sequencing data of exotic pigs (60 animals) from public data repository were used in the study. The principal component analysis (PCA), admixture analysis and phylogenetic analysis revealed that Indian breeds were closer in ancestry to Chinese breeds than European breeds. European breeds exhibited highest genetic diversity measures among all the considered breeds. Among Indian breeds, Agonda Goan and Ghurrah were found to be more genetically diverse than Nicobari and Ghungroo. The selection signature regions in Indian pigs were explored using iHS and XP-EHH, and during iHS analysis, it was observed that genes related to growth, reproduction, health, meat quality, sensory perception and behavior were found to be under selection pressure in Indian pig breeds. Strong selection signatures were recorded in 24.25-25.25 Mb region of SSC18, 123.25-124 Mb region of SSC15 and 118.75-119.5 Mb region of SSC2 in most of the Indian breeds upon pairwise comparison with European commercial breeds using XP-EHH. These regions were harboring some important genes such as EPHA4 for thermotolerance, TAS2R16, FEZF1, CADPS2 and PTPRZ1 for adaptability to scavenging system of rearing, TRIM36 and PGGT1B for disease resistance and CCDC112, PIAS1, FEM1B and ITGA11 for reproduction.

ITGB2 is a central hub-gene associated with inflammation and early fibro-atheroma development in a swine model of atherosclerosis

Background and aim

The complex dynamic interplay between different biological pathways involved in atherosclerosis development has rendered the identification of specific therapeutic targets a challenging quest. We aimed to identify specific genes and mechanistic pathways associated with the early development of fibro-atheromas in a swine model of atherosclerosis.

Methods

The Wisconsin Miniature Swine™ model of Familial Hypercholesterolemia (WMS-FH, n = 11) and genetically related WMS controls (WMS-N, n = 11) were used. The infrarenal aorta was harvested from both groups for histopathologic and transcriptomic profiling at 12 months. Bioinformatic analysis was performed to identify hub genes and pathways central to disease pathophysiology. The expression of ITGB2, the top ranked hub gene, was manipulated in cell culture and the expression of interconnected genes was tested.

Results

Fibro-atheromatous lesions were documented in all WMS-FH aortic tissues and displayed internal elastic lamina (IEL) disruption, significant reduction of myofibroblast presence and disorganized collagen deposition. No fibro-atheromas were observed in the control group. A total of 266 differentially expressed genes (DEGs) were upregulated in WMS-FH aortic tissues, while 29 genes were downregulated. Top identified hub genes included ITGB2, C1QA, LCP2, SPI1, CSF1R, C5AR1, CTSS, MPEG1, C1QC, and CSF2RB. Overexpression of ITGB2 resulted in elevated expression of other interconnected genes expressed in porcine endothelial cells.

Conclusion

In a swine translational model of atherosclerosis, transcriptomic analysis identified ITGB2 as a central hub gene associated inflammation and early fibroatheroma development making it a potential therapeutic target at this stage of disease.

Effect of Caloric Restriction on Metabolic Dysfunction of Young Rapacz Familial Hypercholesterolemic Swine (Sus scrofa)

The Rapacz familial hypercholesterolemic (FH) swine model is well-characterized and used for studies of both spontaneous and inducible atherosclerosis but has not been used for studies of metabolic dysfunction to date. We examined whether parameters of metabolic syndrome including weight and adiposity, serum cholesterol, and glucoregulatory function could be modulated by restriction of caloric intake in the FH swine. Three groups of FH swine (n = 6 per group) were fed without restriction (AL), 80% of AL caloric intake, or 60% of AL caloric intake for 8.8 ± 0.5 mo beginning 2 wk after weaning. Caloric intake influenced the rate and magnitude of body weight gain and change in adiposity, as determined by dual-emission X-ray absorptiometry. At the conclusion of the study, pigs in the AL group reached a total least-square mean body weight of 94.2 kg and fat mass of 31.1%, whereas those fed 80% AL were 71.6 kg and 24.3% fat, and swine fed 60% AL were 46.1 kg and 14.1% fat. Serum cholesterol was greater in AL than 60% AL pigs at the end of the study. At 10 mo of age, intravenous glucose tolerance testing, performed to assess glucoregulatory function, indicated significant differences in serum glucose clearance profiles and insulin sensitivity between the AL- and 60% AL-fed swine. The AL-fed animals showed almost 5-fold lower insulin sensitivity when compared with animals fed 60% AL caloric intake. These results highlight the value of the FH swine model to study metabolic dysfunction due to changes in caloric intake.

Miniature Swine for Preclinical Modeling of Complexities of Human Disease for Translational Scientific Discovery and Accelerated Development of Therapies and Medical Devices

Noncommunicable diseases, including cardiovascular disease, diabetes, chronic respiratory disease, and cancer, are the leading cause of death in the world. The cost, both monetary and time, of developing therapies to prevent, treat, or manage these diseases has become unsustainable. A contributing factor is inefficient and ineffective preclinical research, in which the animal models utilized do not replicate the complex physiology that influences disease. An ideal preclinical animal model is one that responds similarly to intrinsic and extrinsic influences, providing high translatability and concordance of preclinical findings to humans. The overwhelming genetic, anatomical, physiological, and pathophysiological similarities to humans make miniature swine an ideal model for preclinical studies of human disease. Additionally, recent development of precision gene-editing tools for creation of novel genetic swine models allows the modeling of highly complex pathophysiology and comorbidities. As such, the utilization of swine models in early research allows for the evaluation of novel drug and technology efficacy while encouraging redesign and refinement before committing to clinical testing. This review highlights the appropriateness of the miniature swine for modeling complex physiologic systems, presenting it as a highly translational preclinical platform to validate efficacy and safety of therapies and devices.

Identification of network-based biomarkers of cardioembolic stroke using a systems biology approach with time series data

BACKGROUND

Molecular signaling of angiogenesis begins within hours after initiation of a stroke and the following regulation of endothelial integrity mediated by growth factor receptors and vascular growth factors. Recent studies further provided insights into the coordinated patterns of post-stroke gene expressions and the relationships between neurodegenerative diseases and neural function recovery processes after a stroke.

RESULTS

Differential protein-protein interaction networks (PPINs) were constructed at 3 post-stroke time points, and proteins with a significant stroke relevance value (SRV) were discovered. Genes, including UBC, CUL3, APP, NEDD8, JUP, and SIRT7, showed high associations with time after a stroke, and Ingenuity Pathway Analysis results showed that these post-stroke time series-associated genes were related to molecular and cellular functions of cell death, cell survival, the cell cycle, cellular development, cellular movement, and cell-to-cell signaling and interactions. These biomarkers may be helpful for the early detection, diagnosis, and prognosis of ischemic stroke.

CONCLUSIONS

This is our first attempt to use our theory of a systems biology framework on strokes. We focused on 3 key post-stroke time points. We identified the network and corresponding network biomarkers for the 3 time points, further studies are needed to experimentally confirm the findings and compare them with the causes of ischemic stroke. Our findings showed that stroke-associated biomarker genes at different time points were significantly involved in cell cycle processing, including G2-M, G1-S and meiosis, which contributes to the current understanding of the etiology of stroke. We hope this work helps scientists reveal more hidden cellular mechanisms of stroke etiology and repair processes.

Development of Aortic Valve Disease in Familial Hypercholesterolemic Swine: Implications for Elucidating Disease Etiology

Background

Familial hypercholesterolemia (FH) is a prevalent hereditary disease associated with increased atherosclerosis and calcific aortic valve disease (CAVD). However, in both FH and non‐FH individuals, the role of hypercholesterolemia in the development of CAVD is poorly understood. This study used Rapacz FH (RFH) swine, an established model of human FH, to investigate the role of hypercholesterolemia alone in the initiation and progression of CAVD. The valves of RFH swine have not previously been examined.

Methods and Results

Aortic valve leaflets were isolated from wild‐type (0.25‐ and 1‐year‐old) and RFH (0.25‐, 1‐, 2‐, and 3‐year‐old) swine. Adult RFH animals exhibited numerous hallmarks of early CAVD. Significant leaflet thickening was found in adult RFH swine, accompanied by extensive extracellular matrix remodeling, including proteoglycan enrichment, collagen disorganization, and elastin fragmentation. Increased lipid oxidation and infiltration of macrophages were also evident in adult RFH swine. Intracardiac echocardiography revealed mild aortic valve sclerosis in some of the adult RFH animals, but unimpaired valve function. Microarray analysis of valves from adult versus juvenile RFH animals revealed significant upregulation of inflammation‐related genes, as well as several commonalities with atherosclerosis and overlap with human CAVD.

Conclusions

Adult RFH swine exhibited several hallmarks of early human CAVD, suggesting potential for these animals to help elucidate CAVD etiology in both FH and non‐FH individuals. The development of advanced atherosclerotic lesions, but only early‐stage CAVD, in RFH swine supports the hypothesis of an initial shared disease process, with additional stimulation necessary for further progression of CAVD.

Biology and Diseases of Swine

Swine are used in biomedical research as models for biomedical research and for teaching. This chapter covers normative biology and behavior along with common and emerging swine diseases. Xenotransplantation is discussed along with similarities and differences of swine immunology.

Dissecting the mechanism of carotid atherosclerosis from the perspective of regulation

Carotid atherosclerosis is a chronic inflammatory disease of the arterial wall. The present study aimed to identify changes in the gene expression and regulatory factors for atherosclerotic plaques of carotid atherosclerosis from an early to an advanced stage. The original data were downloaded from the NCBI GEO database under accession no. GSE28829. Differentially expressed genes (DEGs) were detected by the Robust Multiarray Average (RMA). The enriched Gene Ontology (GO) terms and pathways for DEGs using DAVID were subsequently identified. The transcriptional and microRNA (miRNA) regulatory network were constructed for the DEGs. Cis-regulatory signals were also investigated. More genes were activated in the advanced stage compared with the early stage. IGHG1 and SPP1 were upregulated, while MYBL1 and PLD were downregulated. The upregulated genes in the advanced stage were involved in atherosclerosis‑related GO terms such as immune, vascular and cell movement homeostasis. The DEGs were significantly enriched in cell adhesion molecules (CAMs) and the focal adhesion pathway. MMP9 and CFL2 played key roles in the transcriptional regulatory network. Moreover, miR-328 was identified as one of the hubs in the miRNA regulatory network. The results may therefore be used to determine the mechanism involved in carotid atherosclerosis.

Measurements of wall shear stress and aortic pulse wave velocity in swine with familial hypercholesterolemia

PURPOSE

To assess measurements of pulse wave velocity (PWV) and wall shear stress (WSS) in a swine model of atherosclerosis.

MATERIALS AND METHODS

Nine familial hypercholesterolemic (FH) swine with angioplasty balloon catheter-induced atherosclerotic lesions to the abdominal aorta (injured group) and 10 uninjured FH swine were evaluated with a 4D phase contrast (PC) magnetic resonance imaging (MRI) acquisition, as well as with radial and Cartesian 2D PC acquisitions, on a 3T MR scanner. PWV values were computed from the 2D and 4D PC techniques, compared between the injured and uninjured swine, and validated against reference standard pressure probe-based PWV measurements. WSS values were also computed from the 4D PC MRI technique and compared between injured and uninjured groups.

RESULTS

PWV values were significantly greater in the injured than in the uninjured groups with the 4D PC MRI technique (P = 0.03) and pressure probes (P = 0.02). No significant differences were found in PWV between groups using the 2D PC techniques (P = 0.75-0.83). No significant differences were found for WSS values between the injured and uninjured groups.

CONCLUSION

The 4D PC MRI technique provides a promising means of evaluating PWV and WSS in a swine model of atherosclerosis, providing a potential platform for developing the technique for the early detection of atherosclerosis.

Mother's exercise during pregnancy programmes vasomotor function in adult offspring

The intrauterine environment is influenced by maternal behaviour and programmes atherosclerotic disease susceptibility in offspring. The aim of this investigation was to test the hypothesis that mothers' exercise during pregnancy improves endothelial function in 3-, 5- and 9-month-old porcine offspring. The pregnant sows in the exercise group ran for an average of 39.35 ± 0.75 min at 4.81 ± 0.35 km h(-1) each day for 5 days per week for all but the last week of gestation. This induced a significant reduction in resting heart rate (exercised group, 89.3 ± 3.5 beats min(-1); sedentary group, 102.1 ± 3.1 beats min(-1); P < 0.05) but no significant differences in gestational weight gain (65.8 ± 2.1 versus 63.3 ± 1.9%). No significant effect on bradykinin-induced vasorelaxation with and without l-NAME was observed. A significant main effect was identified on sodium nitroprusside-induced vasorelaxation (P = 0.01), manifested by a reduced response in femoral arteries of all age groups from exercised-trained swine. Nitric oxide signalling was not affected by maternal exercise. Protein expression of MYPT1 was reduced in femoral arteries from 3-month-old offspring of exercised animals. A significant interaction was observed for PPP1R14A (P < 0.05) transcript abundance and its protein product CPI-17. In conclusion, pregnant swine are able to complete an exercise-training protocol that matches the current recommendations for pregnant women. Gestational exercise is a potent stimulus for programming vascular smooth muscle relaxation in adult offspring. Specifically, exercise training for the finite duration of pregnancy decreases vascular smooth muscle responsiveness in adult offspring to an exogenous nitric oxide donor.