A custom rat and baboon hypertension gene array to compare experimental models

Blood pressure and the kidney cortex transcriptome response to high-sodium diet challenge in female nonhuman primates

Blood pressure (BP) is influenced by genetic variation and sodium intake with sex-specific differences; however, studies to identify renal molecular mechanisms underlying the influence of sodium intake on BP in nonhuman primates (NHP) have focused on males. To address the gap in our understanding of molecular mechanisms regulating BP in female primates, we studied sodium-naïve female baboons (n = 7) fed a high-sodium (HS) diet for 6 wk. We hypothesized that in female baboons variation in renal transcriptional networks correlates with variation in BP response to a high-sodium diet. BP was continuously measured for 64-h periods throughout the study by implantable telemetry devices. Sodium intake, blood samples for clinical chemistries, and ultrasound-guided kidney biopsies were collected before and after the HS diet for RNA-Seq and bioinformatic analyses. We found that on the LS diet but not the HS diet, sodium intake and serum 17 β-estradiol concentration correlated with BP. Furthermore, kidney transcriptomes differed by diet-unbiased weighted gene coexpression network analysis revealed modules of genes correlated with BP on the HS diet but not the LS diet. Our results showed variation in BP on the HS diet correlated with variation in novel kidney gene networks regulated by ESR1 and MYC; i.e., these regulators have not been associated with BP regulation in male humans or rodents. Validation of the mechanisms underlying regulation of BP-associated gene networks in female NHP will inform better therapies toward greater precision medicine for women.

Hepatic transcript signatures predict atherosclerotic lesion burden prior to a 2-year high cholesterol, high fat diet challenge

The purpose of this study was to identify molecular mechanisms by which the liver influences total lesion burden in a nonhuman primate model (NHP) of cardiovascular disease with acute and chronic feeding of a high cholesterol, high fat (HCHF) diet. Baboons (47 females, 64 males) were fed a HCHF diet for 2 years (y); liver biopsies were collected at baseline, 7 weeks (w) and 2y, and lesions were quantified in aortic arch, descending aorta, and common iliac at 2y. Unbiased weighted gene co-expression network analysis (WGCNA) revealed several modules of hepatic genes correlated with lesions at different time points of dietary challenge. Pathway and network analyses were performed to study the roles of hepatic module genes. More significant pathways were observed in males than females. In males, we found modules enriched for genes in oxidative phosphorylation at baseline, opioid signaling at 7w, and EIF2 signaling and HNF1A and HNF4A networks at baseline and 2y. One module enriched for fatty acid β oxidation pathway genes was found in males and females at 2y. To our knowledge, this is the first study of a large NHP cohort to identify hepatic genes that correlate with lesion burden. Correlations of baseline and 7w module genes with lesions at 2y were observed in males but not in females. Pathway analyses of baseline and 7w module genes indicate EIF2 signaling, oxidative phosphorylation, and μ-opioid signaling are possible mechanisms that predict lesion formation induced by HCHF diet consumption in males. Our findings of coordinated hepatic transcriptional response in male baboons but not female baboons indicate underlying molecular mechanisms differ between female and male primate atherosclerosis.

Therapeutic Potential of Annexin A1 Modulation in Kidney and Cardiovascular Disorders

Renal and cardiovascular disorders are very prevalent and associated with significant morbidity and mortality. Among diverse pathogenic mechanisms, the dysregulation of immune and inflammatory responses plays an essential role in such disorders. Consequently, the discovery of Annexin A1, as a glucocorticoid-inducible anti-inflammatory protein, has fueled investigation of its role in renal and cardiovascular pathologies. Indeed, with respect to the kidney, its role has been examined in diverse renal pathologies, including acute kidney injury, diabetic nephropathy, immune-mediated nephropathy, drug-induced kidney injury, kidney stone formation, and renal cancer. Regarding the cardiovascular system, major areas of investigation include the role of Annexin A1 in vascular abnormalities, atherosclerosis, and myocardial infarction. Thus, this review briefly describes major structural and functional features of Annexin A1 followed by a review of its role in pathologies of the kidney and the cardiovascular system, as well as the therapeutic potential of its modulation for such disorders.

Comparative Analysis of Cellular Immune Responses in Conventional and SPF Olive Baboons (Papio anubis)

Olive baboons (P. anubis) have provided a useful model of human diseases and conditions, including cardiac, respiratory, and infectious diseases; diabetes; and involving genetics, immunology, aging, and xenotransplantation. The development of a immunologically defined SPF baboons has advanced research further, especially for studies involving the immune system and immunosuppression. In this study, we compare normal immunologic changes of PBMC subsets, and their function in age-matched conventional and SPF baboons. Our results revealed that both groups have comparable numbers of different lymphocyte subsets, but phenotypic differences in central and effector memory T-cell subsets are more pronounced in CD4+ T cells. Despite equal proportions of CD3+ T cells among the conventional and SPF baboons, PBMC from the conventional group showed greater proliferative responses to phytohemagglutinin and pokeweed mitogen and higher numbers of IFNγ-producing cells after stimulation with concanavalin A or pokeweed mitogen, whereas plasma levels of the inflammatory cytokine TNFα were significantly higher in SPF baboons. Exposure of PBMC from conventional baboons to various Toll-like (TLR) ligands, including TLR3, TLR4, and TLR8, yielded increased numbers of IFNγ producing cells, whereas PBMC from SPF baboons stimulated with TLR5 or TLR6 ligand had more IFNγ-producing cells. These findings suggest that although lymphocyte subsets share many phenotypic and functional similarities in conventional and SPF baboons, specific differences in the immune function of lymphocytes could differentially influence the quality and quantity of their innate and adaptive immune responses. These differences should be considered in interpreting experimental outcomes, specifically in studies measuring immunologic endpoints.

Proresolving protein Annexin A1: The role in type 2 diabetes mellitus and obesity

BACKGROUND

Annexin A1 (AnxA1) is a protein involved in inflammation resolution that might be altered in obesity-associated type 2 diabetes mellitus (DM), which is a chronic inflammatory disease. The aim of this study was to evaluate AnxA1 serum levels in individuals with and without DM stratified according to the body mass index (BMI), and the dynamic of AnxA1 expression in adipose tissue from humans with obesity and non-obesity.

METHODS

Serum samples were obtained from 41 patients with DM (lean, overweight and obese) and 40 controls, and adipose tissue samples were obtained from 16 individuals with obesity (with or without DM), and 15 controls.

RESULTS

DM patients showed similar AnxA1 serum levels when compared to controls. However, when the individuals were stratified according to BMI, AnxA1 levels were higher in individuals with obesity than lean or overweight, and in overweight compared to lean individuals. Moreover, AnxA1 was correlated positively with IL-6 levels. AnxA1 levels were also positively correlated with BMI, waist circumference and waist-to-hip ratio. Furthermore, higher levels of cleaved AnxA1 were observed in adipose tissue from individuals with obesity, independently of DM status.

CONCLUSIONS

Enhanced levels of AnxA1 in serum of individuals with obesity suggest an attempt to counter-regulate the systemic inflammation process in this disease. However, the higher levels of cleaved AnxA1 in the adipose tissue of individuals with obesity could compromise its anti-inflammatory and proresolving actions, locally. Considering our data, AnxA1 cleavage in the adipose tissue, despite increased serum levels of this protein, and consequently the failure in inflammation resolution, suggests an important pathophysiological mechanism involved in inflammatory status observed in obesity.

Prediction of marker genes associated with hypertension by bioinformatics analyses

This study aimed to explore the underlying marker genes associated with hypertension by bioinformatics analyses. A gene expression profile (GSE54015) was downloaded. The differentially expressed genes (DEGs) between the normotensive female (NF) and hypertensive female (HF), and between the normotensive male (NM) and hypertensive male (HM) groups were analyzed. Gene Ontology (GO) and pathway enrichment analyses were performed, followed by protein-protein interaction (PPI) network construction. The transcription factors (TFs), and the common DEGs between the HF and HM groups were then analyzed. In total, 411 DEGs were identified between the HF and NF groups, and 418 DEGs were identified between the HM and NM groups. The upregulated DEGs in the HF and HM groups were enriched in 9 GO terms, including oxidation reduction, such as cytochrome P450, family 4, subfamily b, polypeptide 1 (Cyp4b1) and cytochrome P450, family 4, subfamily a, polypeptide 31 Cyp4a31). The downregulated DEGs were mainly enriched in GO terms related to hormone metabolic processes. In the PPI network, cytochrome P450, family 2, subfamily e, polypeptide 1 (Cyp2e1) had the highest degree in all 3 analysis methods in the HF group. Additionally, 4 TFs were indentified from the 2 groups of data, including sterol regulatory element binding transcription factor 1 (Srebf1), estrogen receptor 1 (Esr1), retinoid X receptor gamma (Rxrg) and peroxisome proliferator-activated receptor gamma (Pparg). The intersection genes were mainly enriched in GO terms related to the extracellular region. On the whole, our data indicate that the DEGs, Cyp4b1, Cyp4a31 and Loxl2, and the TFs, Esr1, Pparg and Rxrg, are associated with the progression of hypertension, and may thus serve as potential therapeutic targets in this disease.

Baboons as a model to study genetics and epigenetics of human disease

A major challenge for understanding susceptibility to common human diseases is determining genetic and environmental factors that influence mechanisms underlying variation in disease-related traits. The most common diseases afflicting the US population are complex diseases that develop as a result of defects in multiple genetically controlled systems in response to environmental challenges. Unraveling the etiology of these diseases is exceedingly difficult because of the many genetic and environmental factors involved. Studies of complex disease genetics in humans are challenging because it is not possible to control pedigree structure and often not practical to control environmental conditions over an extended period of time. Furthermore, access to tissues relevant to many diseases from healthy individuals is quite limited. The baboon is a well-established research model for the study of a wide array of common complex diseases, including dyslipidemia, hypertension, obesity, and osteoporosis. It is possible to acquire tissues from healthy, genetically characterized baboons that have been exposed to defined environmental stimuli. In this review, we describe the genetic and physiologic similarity of baboons with humans, the ability and usefulness of controlling environment and breeding, and current genetic and genomic resources. We discuss studies on genetics of heart disease, obesity, diabetes, metabolic syndrome, hypertension, osteoporosis, osteoarthritis, and intrauterine growth restriction using the baboon as a model for human disease. We also summarize new studies and resources under development, providing examples of potential translational studies for targeted interventions and therapies for human disease.