bluuebunny/crossref_metadata_2025 huggingface dataset:
Altered Baroreflex‐Mediated Cardiovascular Responses to Acute Hypotension in Heart Failure Patients Compared to Healthy Adults
Authors: Drew Rachel C , Lindblad Chelsea N , Samii Soraya M , Blaha Cheryl A , White Michael J , Sinoway Lawrence I
Published: November 2023

Patients with heart failure (HF) exhibit baroreflex dysfunction, which is associated with increased morbidity and mortality (Mortara et al., 1997). This baroreflex dysfunction, caused in part by heightened sympathetic activation and blunted parasympathetic activation (Floras and Ponikowski, 2015), results in inadequate reflex control of blood pressure (BP; Creager and Creager, 1994). Orthostatic hypotension, a decrease in BP upon standing, is a condition that often occurs in HF, and may be linked with altered baroreflex responsiveness in this population (Cody et al., 1982). However, data on baroreflex‐mediated cardiovascular responses to acute hypotension in HF patients are limited. Therefore, 8 HF patients (7 men; mean ± SEM 65 ± 3 y; 1.74 ± 0.04 m; 89 ± 5 kg; ejection fraction 30.5 ± 3.1 %) and 7 healthy control (CON) adults (6 men; 65 ± 2 y; 1.78 ± 0.03 m; 86 ± 6 kg) underwent 7.5 minutes of unilateral lower‐limb ischemia via inflation of a thigh cuff on one leg to non‐pharmacologically induce acute hypotension upon cuff deflation. Beat‐to‐beat systolic BP, diastolic BP, and mean arterial BP (MAP; photoplethysmographic finger cuff) and heart rate (HR; electrocardiogram) were recorded continuously before, during, and after cuff inflation. Statistical analysis involved independent‐samples t‐tests. Baseline values were not different between groups (systolic BP: 128 ± 8 vs. 128 ± 4 mmHg; diastolic BP: 73 ± 3 vs. 82 ± 5 mmHg; MAP: 90 ± 3 vs. 97 ± 4 mmHg; HR: 62 ± 2 vs. 56 ± 2 b.min−1 for HF and CON, respectively; P > 0.05). The magnitude of the induced decrease in MAP was similar in both groups (HF −11 ± 1 vs. CON −12 ± 2 mmHg; P > 0.05). However, the time‐to‐peak MAP decrease was significantly longer in HF compared to CON (HF 11 ± 2 vs. CON 6 ± 1 s; P < 0.05). The magnitude of the resultant HR increase was not different between groups (HF 2 ± 1 vs. CON 4 ± 1 mmHg; P > 0.05). However, the time‐to‐peak HR increase was longer in HF compared to CON (HF 9 ± 1 vs. CON 6 ± 1 s; P < 0.05). In conclusion, these results demonstrate that in response to acute hypotension, HF patients exhibit prolonged hypotension and a delayed tachycardic response. These findings suggest that baroreflex‐mediated cardiovascular responses to acute hypotension are altered in HF compared to CON, which may be linked to the higher occurrence of orthostatic hypotension experienced in this population.

Support or Funding Information

Supported by National Institutes of Health grants UL1 TR000127 and P01 HL096570, and British Heart Foundation travel grant FS/12/18/29522
Device‐Guided Slow Breathing Lowers Blood Pressure and Muscle Sympathetic Nerve Activity Acutely in Prehypertensive Patients with Post‐Traumatic Stress Disorder (PTSD)
Authors: Park Jeanie , Downey Ryan , Kankam Melanie , Norrholm Seth , Rothbaum Barbara
Published: November 2023

Patients with post‐traumatic stress disorder (PTSD) have elevated sympathetic nervous system (SNS) reactivity and impaired arterial and cardiovagal baroreflex sensitivity (BRS) that contribute to increased risk of developing hypertension and cardiovascular disease. Device‐ guided slow breathing (DGB) during which respiratory rate is guided to subphysiologic rates of ~5 breaths/min using a biofeedback device has been shown to lower blood pressure (BP) and sympathetic activity in hypertensive patients. We hypothesized that DGB acutely lowers BP, heart rate (HR), and improves arterial and cardiovagal BRS in Veterans with PTSD. In 10 prehypertensive Veterans with PTSD, we measured continuous beat‐to‐beat arterial BP, EKG, and muscle sympathetic nerve activity (MSNA) at rest, and during 15 minutes of DGB (RESPeRATE). BRS was assessed using the modified oxford technique by which BP was decreased and increased using intravenous boluses of nitroprusside and phenylephrine. Cardiovagal BRS and sympathetic BRS were quantified as the slope of the linear regression between systolic BP (SBP) and R‐R interval, and diastolic BP (DBP) and MSNA burst incidence (BI) and total activity (TA), respectively. BRS assessments were made once at baseline, and repeated once during the last 5 minutes of DGB. Study participants had prehypertension (mean BP 130±4/76±2 mmHg) and had confirmed PTSD. After 10 minutes of DGB, there was a significant reduction in SBP (by −9±2 mmHg, p=0.002) and mean arterial pressure (MAP, by −4±1 mmHg, p=0.009), and a trend towards reduced DBP (−2±1 mmHg, p=0.08). There was no significant change in HR (p=0.21) with DGB. There was also a significant reduction in MSNA burst frequency (29±3 vs. 21±2 bursts/min, p=0.009), and MSNA BI (46±4 vs. 35±4 bursts/100 heart beats, p=0.004) from baseline to end of DGB. There was no significant change in sympathetic BRS quantified using both MSNA BI (p=0.19) and total activity (p=0.22), or cardiovagal BRS (p=0.24), from baseline to during DGB. DGB acutely lowers BP and MSNA, but does not improve sympathetic or cardiovagal BRS in prehypertensive veterans with PTSD. Whether long‐term DGB chronically improves resting BP, SNS activity, and arterial BRS in PTSD should be tested in future studies.

Support or Funding Information

Supported by VA Merit Grant 1I01CX001065; American Heart Association 15CSA24340001
Group III/IV muscle afferents contribute to carotid baroreflex resetting during evoked contractions in humans
Authors: Hureau Thomas J , Weavil Joshua C , Thurston Taylor S , Broxterman Ryan M , Nelson Ashley D , Bledsoe Amber D , Jessop Jacob E , Richardson Russell S , Wray D Walter , Amann Markus
Published: November 2023

Background

Arterial baroreflexes play an important role in the control and regulation of the cardiovascular response to exercise. In fact, carotid baroreflex control of arterial blood pressure needs to be reset during exercise to tolerate the higher blood pressures associated with physical activities. This resetting of carotid baroreflex control to operate at a higher blood pressure during exercise is thought to be mediated by both feedback and feed forward mechanisms.

Purpose

To investigate the contribution of group III/IV muscle afferents to the carotid baroreflex control during evoked quadriceps contractions, devoid of feed forward input (i.e. no central command).

Methods

Eight recreationally active males (29 ± 5 yrs) performed electrically evoked isometric quadriceps contractions for 10 min (femoral nerve stimulation, 40 Hz, 50‐s on, 10‐s off) under control conditions (CTRL) and following lumbar intrathecal fentanyl (FENT) injection to impair feedback from μ‐opioid receptor sensitive lower limb muscle afferents. Carotid baroreflex function was assessed by applying rapid 5‐s pulses of neck pressure (NP, +40 mmHg) or suction (NS, −60 mmHg) via a customized collar. Heart rate (HR) and mean arterial pressure (MAP) were derived from a 12‐lead ECG and a radial arterial catheter, respectively. The carotid baroreflex operating point was determined using the average pre‐stimulus values for HR and MAP.

Results

Resting HR (~70 bpm) and MAP (~87 mmHg) were similar between CTRL and FENT conditions (P > 0.4). FENT administration did not alter the cardiac response to NP (+9 ± 3 bpm; P = 0.99) or NS (−24 ± 11 bpm; P = 0.49) at rest. Similarly, FENT did not alter changes in MAP in response to NP (+13 ± 5 mmHg; P = 0.85) or NS (−13 ± 5 mmHg; P = 0.99) at rest. During exercise, FENT attenuated both HR (82 ± 10 bpm vs 93 ± 14 bpm; P < 0.05) and MAP (100 ± 14 mmHg vs 112 ± 14 mmHg; P < 0.05). However, similar to resting responses (P > 0.4), the cardiac response to NP (+11 ± 4 bpm) or NS (−23 ± 9 bpm) was similar during CTRL and FENT exercise (P > 0.5). Furthermore, changes in MAP in response to NP (+12 ± 4 mmHg) or NS (−14 ± 5 mmHg) were similar during CTRL and FENT exercise (P > 0.4).

Conclusion

Inhibition of group III/IV muscle afferents during evoked muscle contractions reduced the operating point for both HR and MAP, suggesting this feedback pathway is important for carotid baroreflex resetting during exercise. However, carotid baroreflex responsiveness at rest and during exercise was preserved despite muscle afferent blockade, indicating that group III/IV muscle afferents do not govern the carotid baroreflex control of HR and MAP.

Support or Funding Information

The authors were supported by National Heart, Lung, and Blood Institute grants (HL‐103786 and HL‐116579) and a Veterans Affairs Spire grant (E1572P).
Effects of nitrous oxide sedation on sympathetic baroreflex sensitivity
Authors: Isono Kazushige , Okada Yoshiyuki , Mitsui Tatsuhisa , Higuchi Yudai , Masuda Yuji , Ogasawara Tadashi
Published: November 2023

The number of patients with cardiovascular diseases is still growing worldwide, which may increase the risk for cardiovascular events associated with pain stimulation during medical and dental treatments. Nitrous oxide provides minimal and moderate sedation and suppresses pressor responses to pain. We found that an increase in heart rate (HR) in response to pain stimulation remained unchanged by nitrous oxide inhalation, while an increase in muscle sympathetic nerve activity (MSNA) was attenuated, suggesting that blood pressure (BP) control during nitrous oxide sedation may be modified via MSNA. We evaluated whether sympathetic baroreflex sensitivity (BRS) would be decreased by nitrous oxide sedation. Arm cuff and beat‐to‐beat BP (finger photoplethysmography), HR, MSNA (microneurography), cardiac output (Qc) and stroke volume (SV) were measured during inhalation of room air, 100% oxygen, 30%, 40% nitrous oxide, and room air (recovery) for 20 min through a mask, respectively, in 9 young men [age 31±2 (SD) yrs]. Sympathetic BRS was analyzed from the spontaneous changes in beat‐by‐beat diastolic BP and corresponding MSNA (burst incidence and total MSNA) during the last 5 min of each condition. Systolic and diastolic BP did not differ among the inhalation conditions. HR, Qc, and SV were also similar between any conditions. Sympathetic BRS was remained unchanged by inhalation sedation with any nitrous oxide concentration (burst incidence : −3.16 ±1.77, −2.98 ± .02, −2.86 ± 2.05, −2.19 ± 1.95, and−2.21 ± 1.34; P= 0.204 total MSNA : −6.56 ± 2.89, −6.79 ± 4.89, −6.89 ± 5.25, −4.75 ± 3.86, and −5.14 ± 3.44; P= 0.161). These results suggest that baroreflex function is maintained during nitrous oxide sedation and nitrous oxide itself does not directly affect BP regulations.

Support or Funding Information

Supported by JSPSKAKENHI 16K20705.
Role of Brain Derived Neurotrophic Factor in the Supraoptic Nucleus on Response to Salt Loading
Authors: Balapattabi Kirthikaa , Little Joel T. , Bachelor Martha , Cunningham J. Thomas
Published: November 2023

Previous studies have shown that Brain Derived Neurotrophic Factor (BDNF) contributes to ionic plasticity of vasopressin neurons from the supraoptic nucleus of the hypothalamus (SON) in response to 7 days of salt loading. This ionic plasticity is mediated by BDNF dependent phosphorylation of TrkB receptors and downregulation of KCC2, which alter chloride homeostasis resulting in impairment of baroreceptor inhibition of vasopressin release and an increase in mean arterial pressure that is partially vasopressin dependent. However, the specific source of BDNF is yet to be elucidated. In this study, we used adeno‐associated viral vectors with shRNA to test the hypothesis that the salt loading produces BDNF release from the SON which in turn contributes to changes in chloride homeostasis and increased blood pressure. Adult male Sprague Dawley rats (250–300 g b w) were anesthetized with isoflurane and bilaterally injected in the SON (300 nl) with either an AAV vector containing shRNA against BDNF or a control construct with an mCherry reporter. The vectors were injected at a titer of 1.0 × 1013 GC/ml (Vector Biolabs, Malvern, PA). Two weeks after the stereotaxic injections, some rats from each group were instrumented with radio telemetry transmitters using isoflurane anesthesia for recording mean arterial pressure and heart rate. Rats were then housed in commercial metabolism cages and given water or 2% NaCl to drink for 7 days. Volume of fluid intake, urine excretion, food intake, and body weight were measured during the study along with radio telemetry recording for heart rate, mean arterial pressure and activity. Brain regions were harvested for measuring gene expression and protein content at the end of the 7 days. Seven days of 2% salt loading increased TrKB phosphorylation in the SON of rats injected with the control vector. Virally mediated BDNF knockdown in the SON of salt loaded rats decreased TrkB phosphorylation. However, the increases in blood pressure produced by salt loading were not different between these two groups. Both salt loaded groups also had comparable decreases in body weight and increases in fluid intake. The results suggest that, while locally produced BDNF contributes to TrKB phosphorylation in the SON during salt loading, it is not necessary for the increase in blood pressure.

Support or Funding Information

Supported by grant # R01 HL119458
Modeling human development using insights from organoids and embryos
Authors: Spence Jason
Published: November 2023

Recent breakthroughs have allowed the development of 3‐dimensional (3D) organ‐like “organoid” models, derived from human pluripotent stem cells (hPSC), for many organ systems. These models are physiologically complex and recreate several aspects of the complex organ structure and function seen in vivo. We will discuss ongoing work to develop and implement hPSC derived lung and intestinal organoid model systems in order to gain insights into human organ development and maturation.
The Temporal Effects of DOCA‐Salt on the Renal T Cell Profile is Sex‐Specific
Authors: Hutchinson Justin , Gillis Ellen E , Crislip G Ryan , Musall Jacqueline B , Baban Babak , Sullivan Jennifer C
Published: November 2023

There is growing evidence for a role for T cells in the pathogenesis of hypertension. Previous studies by our laboratory show that hypertensive males have more pro‐inflammatory Th17 cells while females have more anti‐inflammatory T regulatory cells (Tregs); we propose that greater Tregs in females contribute to their lower blood pressure (BP) compared to males. The goal of the current study was to test the hypothesis that Tregs preferentially increase over time in female rats with increases in BP, while Th17 cells will increase to a greater extent in males. Male (M) and female (F) uni‐nephrectomized Sprague Dawley rats (10 weeks of age) were subcutaneously implanted with a deoxycorticosterone acetate (DOCA) pellet (200 mg/rat, 60‐day time release) and given 0.9% NaCl to drink. Subsets of rats were killed following 1, 2, and 3 weeks (wks) of DOCA treatment and kidneys were processed for flow cytometric analysis of T cells; n=6/group per time point. BP was measured in separate DOCA rats via telemetry (n=5–6). DOCA increased BP in both M (basal: 115±4, wk1: 146±3, wk2: 187±2, wk3: 190±2 mmHg; p<0.01) and F rats (basal: 105±3, wk1: 134±5, wk2: 165±8, wk3: 175±8 mmHg; p<0.01). BP was comparable between the sexes at baseline (p=0.2), wk 1 (p=0.07) and wk 3 (p=0.1); M had a higher BP than F at wk 2 (p=0.03). At all time points, females had more Tregs than males, and males had more Th17 cells (effect of sex: p<0.05 for all comparisons). Neither Tregs nor Th17 cells were altered vs. control following 1 wk of DOCA treatment (effect of treatment: p=0.9 for both). After 2 wks of DOCA treatment, Tregs decreased in treated males vs. control but were maintained in females (interaction: p=0.06) and Th17 cells increased in both sexes, although the increase was greater in males (effect of DOCA: p<0.001; interaction: p=0.02). Finally, at wk 3 of treatment, DOCA increased Tregs (effect of DOCA: p<0.01) and Th17 cells (effect of DOCA: p=0.03) in both sexes. We propose that the sex‐specific effects of DOCA on T cells at wk 2 contribute to sex differences in BP. The ability of females to maintain Tregs and thereby limit increases in effector Th17 cells at this time point may be a critical pathway by which they are able to maintain a lower BP relative to males.

Support or Funding Information

R01HL127091‐02

Male Control
Male DOCA
Female Control
Female DOCA

Tregs: Wk 1
4±0.5
4±0.6
5±0.6
5±0.5

Tregs: Wk 2
5±0.8
3±0.5*
6±0.9
7±0.7

Tregs: Wk 3
2±0.3
4±0.3*
4±0.5
7±0.6*

Th17 cells: Wk 1
16±2
17±1
11±1
11±1

Th17 cells: Wk 2
6±0.6
27±3*
4±0.5
17±1*

Th17 cells: Wk 3
17±1
21±3*
11±2
17±3*

All data are expressed as percent of CD3+CD4+ cells;

indicates p<0.05 vs. same sex control.
Sex chromosome complement involvement in vasopressin gene expression induced by water deprivation
Authors: Dadam Florencia , Mecawi André , Cambiasso M.Julia , Antunes‐Rodrigues José , Vivas Laura , Caeiro Ximena E.
Published: November 2023

Vasopressin (AVP) is involved in the control of blood pressure and water balance. Basic and clinical data suggest there are sex differences in the expression and function of AVP that cannot be entirely explained solely as a result of gonadal steroid action. This study aimed to define whether sex chromosome complement (SCC) may differentially modulate sex differences in the vasopressin gene expression in response to osmotic stimulation.

In order to evaluate whether SCC may differentially modulate vasopressin gene expression we used mice of the “four core genotype” model, in which the effect of gonadal sex and SCC are dissociated, allowing comparisons of sexually dimorphic traits between XX and XY females as well as in XX and XY males. Comparing these genotypes, it is possible to segregate the role of a) SCC (comparing mice with the same gonadal type but different SCC: XX vs. XY) b) sex (females vs. male) and c) the interaction of SCC and sex.

To remove the activational effects of sex hormones, that might mask the modulatory action of SCC and the organizational hormonal effects, mice were gonadectomized and 15 days later were submitted to a water deprivation protocol (DEP group). Control groups remained with access to water and normal diet (CON group). Twenty four hours later, brains and plasma of all groups were collected to assess plasma electrolytes and osmolality and to evaluate relative gene expression of AVP at the supraoptic (SON) and paraventricular nuclei (PVN).

The statistical analysis showed a significant effect of treatment for both, osmolality and plasma Cl− levels {F(1,40)=4,91 p <0,05; F(1,39)=4,03 p <0,05 respectively, n=6/group.}, however no sex nor SCC effects were observed. On the contrary, a significant effect of the interaction of treatment and SCC factors was observed in the AVP genetic expression at SON {F(1,13)=5,91 p<0,05} n=3–4/group}. Regardless of sex (male or female) XY‐DEP mice (XY‐male and XY‐female) expressed higher AVP mRNA levels compared to XY‐CON animals. However, XX mice (both XX‐male and XX‐female) showed similar levels of AVP mRNA expression for both controls and deprived groups (XX‐CON and XX‐DEP). At the PVN no statistical significant differences were observed. These results reveal a modulatory effect of sex chromosome complement on water deprived AVP gene expression within the SON, what may underlie sex differences in the regulation of vasopressin secretion.

Support or Funding Information

Supported by: ANPCyT, ISN, SECyT, Mincyt‐Cba, CnPq, CONICET.
Effect of Advanced Maternal Age on Cardiovascular Function in Adult Male and Female Rat Offspring
Authors: Shah Amin , Care Alison Sandra , Cooke Christy Lynn , Morton Jude Sally , Quon Anita , Kirschenman Raven , Davidge Sandra Thomas
Published: November 2023

Pregnancy in advanced maternal age (< 35 yrs of age) increases the risk of immediate and long‐term health complications in mothers and offspring. Using a rat model of advanced maternal age, we have recently demonstrated poor fetal development, decreased litter size, and impaired maternal vascular function. The present study aimed to investigate the cardiovascular health of adult male and female offspring born to dams of advanced maternal age. Echocardiography and isolated working heart techniques were used to assess in vivo cardiac function and ex vivo cardiac function recovery after ischemia/reperfusion (I/R) respectively in 4 month and 12 month adult offspring born to young (4 month) or maternal aged (9.5 month) rat dams. At 4 month of age, ex‐vivo data showed that male offspring from aged dams had significantly decreased cardiac function recovery after I/R compared to offspring from young dams (45.78 ± 9.54% vs. 107.6 ± 4.03%; P< 0.001). In contrast, there was no significant difference in cardiac function recovery after I/R in female offspring born from aged vs young dams (87.6 ± 3.26% vs. 94.79 ± 5.89 %; P=NS); indicating better cardiac tolerance against I/R injury compared to their male counterparts. At 12 month of age, echocardiographic data revealed that compared to offspring from young dams, male offspring from aged dams developed in vivo cardiac diastolic dysfunction as indicated by decreased isovolumic relaxation time (male offspring IVRT; young dam 34.27 ± 2.04 vs. aged dam 27.61 ± 0.99 msec; P< 0.01). In contrast, there was no significant difference in in vivo cardiac function between the groups in female offspring indicating intact in vivo cardiac function. We further evaluated whether aging in the female offspring impacted ex vivo cardiac susceptibility to I/R. Our ex vivo data showed that 12 month old female offspring born from both young and aged dams had a similar basal cardiac power during the pre‐ischemia period and similar percent recovery of cardiac function after I/R injury (female offspring; young dam 102.8 % vs. aged dam 81.08 %, Mann‐Whitney U test: P=NS). In conclusion, aged male offspring born to mothers of advanced maternal age had an increased susceptibility to the development of cardiovascular dysfunction.

Support or Funding Information

This work is funded by grants from the Canadian Institutes of Health Research (MOP 133566), the Women and Children's Health Research Institute through the generous contributions of the Stollery Children's Hospital Foundation and the Royal Alexandra Hospital Foundation. A. Shah is supported by fellowship from the Molly Towell Perinatal Research Foundation Canada. S. Davidge is a Canada Research Chair in Maternal and Perinatal Cardiovascular Health.
The reactive dopamine metabolite 3,4‐Dihydroxyphenylacetaldehyde (DOPAL) is a potent inducer of collagen secretion in human cardiac fibroblasts
Authors: Monroe T. Blake , Anderson Ethan J.
Published: November 2023

Spontaneous generation of reactive sugar‐ and lipid‐derived aldehydes occurs in vivo as a byproduct of oxidative stress, and these aldehydes form protein adducts via electrophilic attack on cysteine and lysine residues. Catecholaldehydes are biogenic aldehydes formed as products of catecholamine metabolism by monoamine oxidase (MAO). MAO catalyzes the oxidative deamination of dopamine to generate 3,4‐dihydroxyphenylacetaldehyde (DOPAL), a reactive molecule that has been shown to be neurotoxic stemming from the reactivity of both catechol and aldehyde groups. Our lab has recently reported that diabetic patients have higher content and activity of MAO in atrial myocardium as compared with age‐matched nondiabetic patients, and that MAO activity in this tissue is associated with postoperative atrial fibrillation. Increased collagen deposition in the heart (i.e., fibrosis) is a well‐known risk factor for arrhythmias, and is also associated with diabetes. Here, we tested the hypothesis that DOPAL‐adducts induce production and secretion of collagen in human cardiac fibroblasts. Fibroblasts were isolated and cultured from right atrial appendage samples obtained from patients during during cardiac surgery. Cells were then treated with bovine serum albumin (BSA) conjugated with DOPAL, N(6)‐Carboxymethyllysine (CML, an advanced glycation end product), and 4‐hydroxynonenal (HNE, a n6 polyunsaturated fatty acid‐derived aldehyde). Collagen type I and III were measured in the media via immunoblot. Collagen content in the media increased with CML‐, HNE‐ and DOPAL‐BSA (P<0.05), as compared with BSA alone (control). Surprisingly, treatment with DOPAL increased type I and type III collagen secretion by 11‐fold and 32‐fold, respectively, compared to vehicle‐treated cells (P<0.05), an effect that was >5‐fold greater than with either CML or HNE. These findings suggest that reactive aldehydes, particularly catecholaldehydes, may significantly contribute to fibrosis in the heart via increased collagen secretion. Further, they provide evidence that compounds with aldehyde‐scavenging capacity may have therapeutic value in mitigating cardiac fibrosis.

Support or Funding Information

R01HL122863‐01
ETB Receptor Dysfunction Leads to Exaggerated Apoptosis and Inflammasome Priming in Renal Outer Medulla during Type 1 Diabetes
Authors: De Miguel Carmen , Liu Xiaofen , Pollock David M. , Pollock Jennifer S.
Published: November 2023

Endothelin‐1 (ET‐1), a potent vasoactive peptide that acts through two receptors (ETA and ETB), has been implicated as a causative factor in animal models of diabetes‐induced kidney injury and is upregulated in patients with diabetic nephropathy. Renal infiltration of immune cells and increased production of inflammatory markers play a critical role in the pathogenesis of diabetic kidney disease. ET‐1 exerts pro‐inflammatory actions in the diabetic kidney; however, the mechanism(s) by which ET‐1 mediates these effects are unclear. We hypothesized that the ETB receptor mediates renal protection during type 1 diabetes (T1D)‐induced apoptosis and inflammasome activation. Diabetes was induced in ETB deficient (ETB def) and transgenic (TG) control rats by i.v. injection of streptozotocin (STZ). After 10 wk of T1D, rats were terminated, kidneys were isolated and renal apoptosis was detected by TUNEL assay. Loss of ETB receptor function led to exaggerated apoptosis in kidneys of diabetic ETB def rats, especially in the outer medulla, an area of the kidney particularly rich in ETB receptors. Inflammasomes have been recently implicated in activation of apoptotic pathways. Analysis of the outer medulla by RT‐PCR array demonstrated that T1D induces a 4‐fold upregulation of NLRP5 (n=3/group; p<0.05) and a 3‐fold increase of IL‐1β expression (n=3/group; p<0.05) in ETB def rats when compared to diabetic TG controls, while NLRP3 was not different between genotypes. In addition, the negative regulator of the inflammasome PSTPIP1 was decreased in outer medulla of diabetic ETB def rats, further suggesting an activation of inflammasome signaling pathways in this part of the kidney. Recently, endoplasmic reticulum (ER) stress has been identified as an inducer of inflammasome activation; thus, we determined whether diabetic ETB def rats had an exaggerated ER stress response in the outer medulla. Outer medullary RNA expression of GRP78, ATF‐4, ATF‐6, s‐XBP‐1, CHOP and caspase‐12 was not different between genotypes in T1D. In conclusion, absence of functional ETB receptors in diabetes is associated to priming of inflammasomes and exaggerated apoptosis in the renal outer medulla. These results highlight the protective role of ETB receptors against the development of diabetic kidney damage, especially in the renal outer medulla.

Support or Funding Information

Funded by NIH T32 DK007545 to CDM and P01 HL95499 to DMP and JSP.
Fructose Induces Metabolic Syndrome Associated with a Marked Inflammatory State
Authors: Santos Fernando , Moreira Edson Dias , De Angelis Katia , Irigoyen Maria Claudia
Published: November 2023

Owing to controversial effects of fructose consumption, this protocol aims to identify possible changes on inflammatory profile due chronic fructose exposure. Male Wistar rats (weighing 150g at the beginning) were divided in two experimental groups,: Control group (CG), followed for 90 days and fructose group (FG), treated with 10% of fructose in drink water for 90 days Blood pressure was monitored in both groups by DSI® telemetry sensor.. Each animal was allocated individually under controlled environment (temperature: 20–22°C, 12h‐12h light‐dark cycle and soundproof room) with free access to food and water. It was observed that fructose was able to induce metabolic syndrome (MS) after 90 days, evidenced by increased abdominal adipose tissue (FG 12.3±0.6g vs. CG 6.2±0.8g), systolic arterial pressure (FG 146±5.2mmHg vs. CG 119±3.2mmHg), glycaemia (FG 98±1.3mg/dl vs. 81±2.0mg/dl) and triglycerides (FG 161±5.0mg/dl vs. CG 112±3.2mg/dl). The obesity and higher levels of triglycerides caused lipid deposition on kidney of FG. These factors were associated with increase in inflammatory markers evaluated by immunohistochemistry (IL‐6: 4.3±0.7% and NFκB: 0.6±0.1%) when compared to CG (IL‐6: 0.8±0.2% and NFκB: 0.2±0.03%). Furthermore, fructose promoted alteration in cardiac inflammatory profile. There were increase in NFκB (FG 19.1±4.3% vs. CG 6.3±1.2%) and TNFα (FG 25.1±1.4ρg/mg vs. CG 17.1±2.2ρg/mg). These results were associated with an increased action of sympathetic nervous system probably due to fructose consumption, since sympathetic modulation (FG 10.3±1.2mmHg2 vs. CG 4.2±0.3mmHg) evaluated by spectral analyses was increased in the fructose –treated animals. In addition an increase of 74% on expression of cardiac β1 adrenergic receptor was detected in FG. We concluded that chronic consumption of fructose was able to induce MS and to promote a proinflammatory profile dependent on increased lipid deposition and sympathetic modulation.

Support or Funding Information

FAPESP 2013/23418‐0
A Genome‐Spanning Map of Chromatin Structure near the Renin Proximal Promoter
Authors: Stodola Timothy , Liu Pengyuan , Liu Yong , Greene Andrew , Liang Mingyu
Published: November 2023

Emerging evidence suggests the expression of a gene can be regulated by interactions between the gene and genomic regions distant in sequence or on a different chromosome. Chromatin conformation capture with sequencing (3C‐seq) allows high resolution mapping of chromatin structure and enables the determination of all genomic regions that interact with a region of interest. The renin‐angiotensin system (RAS) is one of the major regulatory mechanisms essential for maintaining cardiovascular homeostasis through actions on the kidney and throughout the cardiovascular system. The goal of the current study was to expand our understanding of renin regulation by identifying potential trans‐regulatory elements of renin more than a few kilobases from the renin promoter, using 3C‐seq in isolated SS/JrHrdMcwi cardiac microvascular endothelial cells. Three biological replicates of ten million cells were fixed, digested with EcoRI, ligated, and then decrosslinked. Secondary digestion with NlaIII followed by a second ligation allowed a bait sequence, at the renin promoter, to surround an unknown captured sequence. A sequencing library was prepared using PCR with primers specific to the EcoRI and NlaIII cuts sites at the renin promoter to identify the captured sequences. Sequence reads of captured segments were mapped to rat genome (Rn 5) divided into fragments cut by EcoRI (fragends). The read counts were binarized and Z‐scores calculated for each fragend based on a window surrounding that fragend relative to background. Regions with Z‐score above a threshold Z‐score with false discovery rate ≤ 0.01 in three biological replicates were considered significant interactions. We found 18 genome‐spanning regions consistently interacting with the renin proximal promoter. Interactions were found on Chr13, the chromosome where Ren is located, as well as chromosomes 1, 2, 3, 7, 9, 12, 14 and 15. Quantitative PCR in 6 new 3C samples were used to validate identified interactions and negative control regions not expected to interact. These findings suggest renin expression might be regulated by chromatin conformation involving several chromatin regions located throughout the genome.

Support or Funding Information

NIH P01HL116264‐04
Angiotensin converting enzyme enhances the oxidative response and bactericidal activity of neutrophils
Authors: Bernstein Kenneth E , Khan Zakir , Shen Xiao Z , Bernstein Ellen A , Giani Jorge F , Eriguchi Masahiro , Zhao Tuantuan V , Gonzalez‐Villalobos Romer A , Fuchs Sebastien , Liu George Y
Published: November 2023

We studied the role of angiotensin converting enzyme (ACE) in neutrophils. ACE knockout (KO) mice or mice treated with an ACE inhibitor were more susceptible to bacterial infection by methicillin‐resistant S. aureus (MRSA). Specifically, KO mice have larger skin lesions (4‐fold) and more bacteria per lesion (3.3‐fold) compared to wild type (WT). WT mice transplanted with ACE KO bone marrow are also significantly more susceptible than WT mice transplanted with WT bone marrow. In contrast, mice over expressing ACE in neutrophils (NeuACE mice) have increased resistance to MRSA (smaller lesions, less bacteria), and better in vitro killing of MRSA, P. aeruginosa, and K. pneumoniae. ACE overexpression increased neutrophil production of reactive oxygen species (ROS) following MRSA challenge, an effect independent of the angiotensin II AT1 receptor. Specifically, as compared to WT mice, there was a marked increase of SOD inhibitable superoxide generation (greater than 2‐fold, p<0.0005) in NeuACE neutrophils following MRSA infection. These functional studies and the increased association of cytosolic subunits of NADPH oxidase (p47‐phox, p67‐phox) with membrane gp91‐phox indicate that ACE directly affects NADPH oxidase activity. Myloperoxidase activity in neutrophils was equivalent to that of WT mice. Increased ROS generation mediates the enhanced bacterial resistance of NeuACE mice as the enhanced resistance is lost with DPI inhibition or with ACE inhibitors. NeuACE granulocytes also have increased neutrophil extracellular trap formation (NET) and IL‐1β release in response to MRSA. In a mouse model of chemotherapy‐induced neutrophil depletion, transfusion of ACE overexpressing neutrophils was superior to WT neutrophils in treating MRSA infection. These data indicate a previously unknown function of ACE in neutrophil anti‐bacterial defenses, and suggest caution in the treatment of certain individuals with ACE inhibitors. ACE overexpression in neutrophils may be useful in boosting the immune response to antibiotic resistance bacterial infection.

Support or Funding Information

NIH grants R01DK098382 (KEB), R21AI114965 (KEB), and R03DK101592 (RAGV).
Establishment of salt‐induced chronic kidney disease in stroke‐prone spontaneously hypertensive rats (SHRSP) and its therapeutic effect of kefir‐derived peptides oral administration
Authors: Chen Yu‐Hsuan , Chen Hsiao‐Ling , Chen Chuan‐Mu
Published: November 2023

The consequence of chronic high blood pressure is increasingly prevalence of chronic kidney disease (CKD) and cardiovascular organ injury, prevalence the high costs and poor outcomes of treatment are a significant health issue at clinical. In this study, hypothesis the Kefir‐fermented product derived from milk protein (as a nature source) with the protection of the kidney function in management of salt‐induced chronic kidney disease. Therefore, we used the salt‐induced kidney disease in stroke‐prone spontaneously hypertensive rats (SHRSP) as an animal model. SHRSP rats at 50–60 weeks of age were orally administered kefir‐derived peptides (KDP) for four weeks. The results of KDP have good performance of anti‐ hypertension effect, further studies of immunohistochemical staining and western blotting showed that salt‐induced kidney failure significantly increased the protein levels of CD68, MCP‐1, α‐SMA and ET‐1 under 1% NaCl drinking water induction. However, treatment with KDP significantly decreased macrophage infiltration marker CD68, MCP‐1, α‐SMA and ET‐1 levels compared to those in mock group of salt‐treated SHRSP rats (P<0.05). Moreover, the results demonstrated that KDP improved salt‐induced impaired kidney function. The examination of kidney histopathology further showed that KDP administration significantly decreased salt‐induced glomerulosclerosis, tubular damage, collagen deposition, interlobular arterial thickness (P<0.05). These conclusion suggested that KDP exerted potent protection against salt‐induced chronic kidney disease and antihypertension in SHRSP rats. Therefore, kefir‐derived peptides may represent a novel kidney protective agent in clinical use.
Loss of Bmal1 impairs the diurnal rhythm in sodium excretion that parallels the loss of circadian blood pressure rhythm
Authors: Zhang Dingguo , Najarro Guillermo , Chen Daian , Obi Ijeoma , Jin Chunhua , Speed Joshua , Pollock Jennifer , Pollock David
Published: November 2023

High salt intake correlates with elevated levels of blood pressure, leading to an increased risk of cardiovascular disease. Abnormal diurnal rhythm in sodium excretion is often found in patients that exhibit non‐dipping of blood pressure. Our recent findings suggest that high salt diet alters clock gene expression patterns. The current study was designed to test the hypothesis that the circadian gene Bmal1 regulates diurnal electrolyte excretion and blood pressure in response to different levels of dietary salt. We utilized Bmal1 knockout (Bmal1KO) (n=6) and wildtype (WT) mice in metabolic cages under normal (0.4%) and high salt (4%) diets and collected urine during active (lights‐off) and inactive (lights‐on) phases. We found that urinary sodium excretion in WT mice was higher during the active phase and lower during the inactive phase in response to normal or high salt diet (normal salt: 41±4μEq/12h vs. 21±5μEq/12h; high salt: 490±50μEq/12h vs. 100±20μEq/12h). Interestingly, in Bmal1KO mice the difference in sodium excretion was not significant between active and inactive phases (normal salt: 20±5μEq/12h vs. 11±4μEq/12h; high salt: 173±35μEq/12h vs. 101±19μEq/12h), indicating loss of diurnal Na+ excretion patterns. Similarly, we found that in WT mice, urinary potassium excretion was higher in the active phase and lower in the inactive phase (normal salt: 85±10μEq/12h vs. 29±12μEq/12h; high salt: 146±9μEq/12h vs. 74±8μEq/12h); however, Bmal1KO mice showed a similar potassium excretion pattern in active and inactive phases under normal salt diet, and an even higher urinary potassium in the inactive phase when challenged with high salt (23±4μEq/12h vs. 38±6μEq/12h). Finally, Bmal1KO mice exhibited a loss of diurnal blood pressure (measured by telemetry) rhythm on both diets. These data suggest that Bmal1 is important for maintaining the diurnal pattern in sodium excretion that mirrors the loss of circadian blood pressure rhythm.
Aldosterone‐regulated miRNAs and their target genes in mouse cortical collecting duct mpkCCD cells
Authors: Kwon Tae‐Hwan , Park Eui‐Jung , Jung Hyun Jun , Choi Hyo‐Jung
Published: November 2023

Background

Mature microRNA (miRNA) is a modulator in the post‐transcriptional regulation. The present study aimed 1) to profile the aldosterone‐regulated miRNAs in mouse cortical collecting duct cells (mpkCCDc14 cells); 2) to identify the main signaling pathways where putative target genes of identified miRNAs are enriched; and 3) to determine the roles of selected miRNAs and target genes in aldosterone‐mediated action.

Methods

Microarray chip assay (Affymetrix GeneChip miRNA 4.0 array) was done in the mpkCCDc14 cells in the absence or the presence of aldosterone treatment (10−6 M) for 3 d. The candidate miRNAs were selected by 1) more or less than 30% of significant fold‐changes (Protocol 1), or 2) differential expression analysis carried out using the R package ‘bridge’ (Bayesian Robust Inference for Differential Gene Expression. R package version 1.34.0., Protocol 2). Both the putative target genes of identified miRNAs and miRNAs‐enriched pathways were analyzed by using DIANA‐mirPath program.

Results

Twenty‐nine miRNAs were significantly up‐regulated (> 1.3‐fold) and 27 miRNAs were markedly down‐regulated (< 0.7‐fold) in mpkCCDc14 cells after aldosterone treatment (Protocol 1). Moreover, 5 up‐regulated and 7 down‐regulated miRNAs (> 1.2‐fold and < 0.8‐fold) were selected with high posterior probabilities (> 0.95, Protocol 2). Putative target genes of identified miRNAs were associated with 55 KEGG pathways (Protocol 1) and 29 KEGG pathways (Protocol 2) by DIANA‐mirPath program analysis. Among them, Wnt signaling pathway was particularly the most highly ranked. Seven up‐regulated and 8 down‐regulated mature miRNAs were enriched in the Wnt signaling pathways. Their quantitative changes were further examined by qPCR, revealing that miR‐130b‐3p, miR‐34c‐5p and miR‐146a‐5p were significantly changed. Six target genes (Rock1, skp1a, Tbl1xr1, Ppp2re, Wnt2b, Plcb1) of miR‐130b‐3p, 6 target genes (Lef1, Camk2b, Tbl1xr1, Prickle1, Ppp2r5a, Daam1) of miR‐34c‐5p and 4 target genes (Ppp3r2, Cxxc4, Smad4, Nfat5) of miR‐146a‐5p were identified.

Conclusion

Aldosterone induces significant changes of miRNAs expression in mpkCCDc14 cells, and Wnt signaling is the most highly ranked pathway where identified miRNAs are enriched. The changes of target genes and corresponding protein expression may potentially be involved in the aldosterone‐mediated renal fibrosis, which need to be further examined.
Dasatinib, a non‐receptor tyrosine kinase inhibitor, induces aquaporin‐2 membrane accumulation in a phospho‐serine 256 independent manner.
Authors: Bouley Richard , Cheung Pui Wen , Terlouw Abby , Brown Dennis
Published: November 2023

The cAMP‐sensitive water channel (AQP2) plays an important role in water regulation in the renal collecting ducts. Upon stimulation by vasopressin (VP), AQP2 is phosphorylated at the c‐terminus on serine 256 (pS256). This event leads to AQP2 accumulation in the plasma membrane. Other serine residues including S264 and S269 are also phosphorylated, but phosphorylation of S256 is thought to be essential to AQP2 membrane accumulation, and has to precede phosphorylation of other serine residues. Here we show that by inhibiting the proto‐oncogene tyrosine‐protein kinase Src using dasatinib, we can induce AQP2 membrane accumulation in a S256 independent but S269 dependent manner.

Immunostaining using anti‐AQP2 antibody shows that dasatinib increases AQP2 membrane accumulation in LLC‐AQP2 cells. This result was confirmed with other Src inhibitors, bosutinib and KX2‐391. Furthermore, dasatinib also increases apical membrane AQP2 accumulation in collecting duct principal cells in our in situ kidney slice model. Dasatinib does not increase cAMP or PKA activity, and western blot analysis using specific phospho‐AQP2 antibodies showed that, in contrast to VP, dasatinib does not increase phosphorylation of S256 or de‐phosphorylate S261, but does increase the phosphorylation of S269. To confirm the importance of pS269 in dasatinib‐induced AQP2 membrane accumulation, we expressed an AQP2 S269A mutant in the LLC‐PK1 cells. We find that while VP induces AQP2 membrane accumulation in S269A mutant cells, dasatinib does not, suggesting the importance of pS269 for the effect of dasatinib.

Src inhibition by dasatinib reduces endocytosis of rhodamine‐conjugated dextran, and rhodamine‐tagged transferrin accumulates at the cell surface and is not internalized. Immunocytochemistry shows an accumulation of clathrin at the plasma membrane in cells and tissues treated with dasatinib. Taken together, these results suggest that dasatinib reduces endocytosis by inhibiting clathrin‐mediated endocytosis.

In conclusion, Src inhibition by dasatinib induces AQP2 membrane accumulation in a serine 256 independent, serine 269 dependent manner, and it inhibits clathrin‐mediated endocytosis. This study improves our understanding of the diversity of mechanisms that regulate water reabsorption in the kidneys, and allows us to differentially modulate the phosphorylation of essential AQP2 serine residues to understand their physiological functions.

Support or Funding Information

This work was supported by NIH grant DK096586 (D. Brown). P. W. Cheung was supported by T32 grant 5T32DK007540‐29
Linking epigenetic regulation of short chain fatty acid receptors, gut microbiome and hydrogen sulfide in the hypertensive kidney
Authors: Weber Gregory , Pushpakumar Sathnur , Sen Utpal
Published: November 2023

Hypertension is one of the leading causes of chronic kidney disease. Recent studies have highlighted the importance of gut microbiota on physiological processes, such as metabolism and immunity, through production of short chain fatty acids (SCFA), which are linked with blood pressure (BP) regulation. Moreover, host epigenetic regulators, such as microRNAs, can directly affect the microbiome, and therefore blood pressure. However, the precise epigenetic regulation of BP is poorly understood. The gaseous molecule, hydrogen sulfide (H2S) is involved in regulating several physiological processes, however, its role and influence on the host gut microbiome and on renal function remains to be elucidated. In this study, we sought to determine the roles of host microRNAs in regulating short chain fatty acid receptors in the hypertensive kidney and whether H2S donor, GYY4137 (GYY), could reverse the effects to mitigate renal dysfunction. C57BL6/J wild‐type mice were treated without or with Ang‐II (1000ng/kg−1/min−1) and GYY (133μM/kg−1/d−1) for 4 weeks. Quantitative PCR, Western blot, immunofluorescence assays, metagenomic sequencing, and glomerular filtration rate were measured. Results indicated that increased expression of miR‐329 and miR‐132 in hypertensive mice were reduced by GYY treatment. SCFA receptors Gpr41 and Gpr43 are expressed in the kidney and are also predicted targets of miR‐329 and miR‐132, respectively. The mRNA and protein expression of the above receptors was reduced in Ang‐II treated mice while animals treated with Ang‐II and GYY showed normalized expression. miR‐129 was induced by GYY supplementation and the predicted SCFA receptor target Olfr78 was decreased in the normal kidney with the opposite effect in hypertensive kidney. Immunofluorescence analysis showed decreased signal of Gpr41 and Gpr43 in the blood vessel and tubules in Ang‐II mice and were normalized in mice treated with GYY. Metagenomic sequencing showed H2S supplementation affected the host gut microbiome composition and improved renal function. In conclusion, our data suggests that microRNAs can regulate SCFA receptors in the kidney and hydrogen sulfide supplementation has a positive effect on renal function through the gut microbiome and SCFA receptors.

Support or Funding Information

DK‐104653 and HL‐104103 to U.S.,

15SDG25840013 to S.P.