Blood pressure, arterial stiffness and endogenous lithium clearance in relation to AGTR1 A1166C and AGTR2 G1675A gene polymorphisms

Cardiovascular Protective Effects of NP-6A4, a Drug with the FDA Designation for Pediatric Cardiomyopathy, in Female Rats with Obesity and Pre-Diabetes

BACKGROUND

Obese and pre-diabetic women have a higher risk for cardiovascular death than age-matched men with the same symptoms, and there are no effective treatments. We reported that obese and pre-diabetic female Zucker Diabetic Fatty (ZDF-F) rats recapitulate metabolic and cardiac pathology of young obese and pre-diabetic women and exhibit suppression of cardio-reparative AT2R. Here, we investigated whether NP-6A4, a new AT2R agonist with the FDA designation for pediatric cardiomyopathy, mitigate heart disease in ZDF-F rats by restoring AT2R expression.

METHODS

ZDF-F rats on a high-fat diet (to induce hyperglycemia) were treated with saline, NP-6A4 (10 mg/kg/day), or NP-6A4 + PD123319 (AT2R-specific antagonist, 5 mg/kg/day) for 4 weeks (n = 21). Cardiac functions, structure, and signaling were assessed by echocardiography, histology, immunohistochemistry, immunoblotting, and cardiac proteome analysis.

RESULTS

NP-6A4 treatment attenuated cardiac dysfunction, microvascular damage (-625%) and cardiomyocyte hypertrophy (-263%), and increased capillary density (200%) and AT2R expression (240%) (p < 0.05). NP-6A4 activated a new 8-protein autophagy network and increased autophagy marker LC3-II but suppressed autophagy receptor p62 and autophagy inhibitor Rubicon. Co-treatment with AT2R antagonist PD123319 suppressed NP-6A4's protective effects, confirming that NP-6A4 acts through AT2R. NP-6A4-AT2R-induced cardioprotection was independent of changes in body weight, hyperglycemia, hyperinsulinemia, or blood pressure.

CONCLUSIONS

Cardiac autophagy impairment underlies heart disease induced by obesity and pre-diabetes, and there are no drugs to re-activate autophagy. We propose that NP-6A4 can be an effective drug to reactivate cardiac autophagy and treat obesity- and pre-diabetes-induced heart disease, particularly for young and obese women.

Renal Sodium Handling in Relation to Environmental and Genetic Factors in Untreated Chinese

BACKGROUND

We investigated proximal and distal renal tubular sodium handling, as assessed by fractional excretion of lithium (FELi) and fractional distal reabsorption rate of sodium (FDRNa), in relation to environmental and genetic factors in untreated patients.

METHODS

Our study participants were suspected hypertensive patients being off antihypertensive medication for ≥2 weeks and referred for 24-hour ambulatory blood pressure monitoring. We collected serum and 24-hour urine for measurement of sodium, creatinine, and lithium concentration, and calculated FELi and FDRNa. We genotyped 19 single-nucleotide polymorphisms associated with renal sodium handling or blood pressure using the ABI SNapShot method.

RESULTS

The 1,409 participants (664 men, 47.1%) had a mean (±SD) age of 51.0 ± 10.5 years. After adjustment for host factors, both FELi and FDRNa were significantly (P ≤ 0.01) associated with season and humidity, explaining ~1.3% and ~3.5% of the variance, respectively. FELi was highest in autumn and lowest in summer and intermediate in spring and winter (P = 0.007). FDRNa was also highest in autumn but lowest in winter and intermediate in spring and summer (P < 0.001). Neither FELi nor FDRNa was associated with outdoor temperature or atmospheric pressure (P ≥ 0.13). After adjustment for host and environmental factors and Bonferroni multiple testing, among the 19 studied genetic variants, only rs12513375 was significantly associated with FELi and FDRNa (P ≤ 0.004) and explained about 1.7% of the variance.

CONCLUSIONS

Renal sodium handling as measured by endogenous lithium clearance was sensitive to major environmental and genetic factors. Our finding is toward the use of these indexes for the definition of renal tubular dysfunction.

Relationship between A1166C polymorphism of angiotensin II type 1 receptor gene and arteriosclerosis: A protocol for systematic review and meta-analysis

BACKGROUND

Arteriosclerosis has genetic correlation. Many studies have shown that angiotensin II type 1 receptor (AT1R) gene A1166C polymorphism is highly associated with arteriosclerosis, but there is no evidence-based basis. The purpose of this study is to systematically evaluate the relationship between AT1R gene A1166C polymorphism and arteriosclerosis.

METHODS

The search time is set from the establishment of the database in December 2020 in this study. The search database include China National Knowledge Infrastructure (CNKI), Wanfang, VIP and China Biology Medicine disc (CBM), PubMed, EMBASE, Web of Science, and the Cochrane Library. The subjects are observational studies on the relationship between AGTR1 A1166C polymorphism and arteriosclerosis (including case-control study, cross-sectional study, and cohort study). The language is limited to English and Chinese. The data of the included study are extracted and the literature quality is evaluated by 2 researchers independently. The data are statistically analyzed by Stata 16.0 software.

RESULTS

This study will use pulse wave velocity as an index to evaluate arteriosclerosis to explore the relationship between AT1R gene A1166C polymorphism and arteriosclerosis.

CONCLUSION

This study will provide evidence-based medicine for elucidating the genetic tendency of arteriosclerosis.

ETHICS AND DISSEMINATION

Private information from individuals will not be published. This systematic review also does not involve endangering participant rights. Ethical approval will not be required. The results may be published in a peer-reviewed journal or disseminated at relevant conferences.

OSF REGISTRATION NUMBER

DOI 10.17605/OSF.IO/V6E2Y.

Angiotensin Type 2 Receptors: Painful, or Not?

Pain in response to various types of acute injury can be a protective stimulus to prevent the organism from using the injured part and allow tissue repair and healing. On the other hand, neuropathic pain, defined as ‘pain caused by a lesion or disease of the somatosensory nervous system’, is a debilitating pathology. The TRPA1 neurons in the Dorsal Root Ganglion (DRG) respond to reactive oxygen species (ROS) and induce pain. In acute nerve injury and inflammation, macrophages infiltrating the site of injury undergo an oxidative burst, and generate ROS that promote tissue repair and induce pain via TRPA1. The latter discourages using the injured limb, with a lack of movement helping wound healing. In chronic inflammation caused by diabetes, cancer etc., ROS levels increase systemically and modulate TRPA1 neuronal functions and cause debilitating neuropathic pain. It is important to distinguish between drug targets that elicit protective vs. debilitating pain when developing effective drugs for neuropathic pain. In this context, the connection of the Angiotensin type 2 receptor (AT₂R) to neuropathic pain presents an interesting dilemma. Several lines of evidence show that AT₂R activation promotes anti-inflammatory and anti-nociceptive signaling, tissue repair, and suppresses ROS in chronic inflammatory models. Conversely, some studies suggest that AT₂R antagonists are anti-nociceptive and therefore AT₂R is a drug target for neuropathic pain. However, AT₂R expression in nociceptive neurons is lacking, indicating that neuronal AT₂R is not involved in neuropathic pain. It is also important to consider that Novartis terminated their phase II clinical trial (EMPHENE) to validate that AT₂R antagonist EMA401 mitigates post-herpetic neuralgia. This trial, conducted in Australia, United Kingdom, and a number of European and Asian countries in 2019, was discontinued due to pre-clinical drug toxicity data. Moreover, early data from the trial did not show statistically significant positive outcomes. These facts suggest that may AT₂R not be the proper drug target for neuropathic pain in humans and its inhibition can be harmful.

Longitudinal data analysis for rare variants detection with penalized quadratic inference function

Longitudinal genetic data provide more information regarding genetic effects over time compared with cross-sectional data. Coupled with next-generation sequencing technologies, it becomes reality to identify important genes containing both rare and common variants in a longitudinal design. In this work, we adopted a weighted sum statistic (WSS) to collapse multiple variants in a gene region to form a gene score. When multiple genes in a pathway were considered together, a penalized longitudinal model under the quadratic inference function (QIF) framework was applied for efficient gene selection. We evaluated the estimation accuracy and model selection performance under different model settings, then applied the method to a real dataset from the Genetic Analysis Workshop 18 (GAW18). Compared with the unpenalized QIF method, the penalized QIF (pQIF) method achieved better estimation accuracy and higher selection efficiency. The pQIF remained optimal even when the working correlation structure was mis-specified. The real data analysis identified one important gene, angiotensin II receptor type 1 (AGTR1), in the Ca2+/AT-IIR/α-AR signaling pathway. The estimated effect implied that AGTR1 may have a protective effect for hypertension. Our pQIF method provides a general tool for longitudinal sequencing studies involving large numbers of genetic variants.