bluuebunny/crossref_metadata_2025 huggingface dataset:
In Vivo Analysis of Cilia Function and Connections to Renal Disease and Physiology
Authors: Yoder Bradley K.
Published: November 2023

Many cystic kidney diseases are caused by defects in proteins required for cilia assembly or activity. It has been proposed that cilia regulate cell proliferation, oriented cell division, responses to tissue injury, and as mechanosensors. The cilium is thought to mediate its effects by regulating the activity of several signaling proteins or channels including Polycystins 1 and 2, mTor, Stat3/6, Hedgehog, and purinergic receptors. Importantly, these signaling pathways are frequently altered when cilia are absent from cells and in cystic renal epithelium. However, the exact mechanisms connecting cilia dysfunction to cyst formation remains largely unknown. Recent data have raised concerns regarding the mechanosensory model for cystogenesis. Despite data from cell culture studies showing fluid flow mediated deflection of cilia results in changes in intracellular calcium levels, this has not been observed in vivo. Further, loss of cilia function in juvenile mice results in rapid cyst formation, but in adult mice cyst do not form for 6 to 8 months after cilia function is disrupted. This is not consistent with simple defects in mechanosensation. Our studies are trying to assess the functions of the cilium in vivo. We are addressing whether it has mechanosensory activities under different physiological conditions and how ciliary defects contribute to cyst formation. We are using conditional mutations in genes required for cilia formation and function along with a series of biosensors to analyze cilia function in live tissues. To begin addressing the in vivo roles of the cilium, we generated a CiliaGFP mouse allowing us to observe cilia in whole tissues of live animals. We found under normal conditions that cilia are consistently bent in the direction of fluid flow along the renal tubule. However, by altering physiological conditions, we show cilia oscillate or even reverse orientation, indicating that the behavior of cilia is dynamic and influenced by other systems in the body. We are determining how cilia react to changes in heart rate, blood pressure, glomerular filtration rates, restricted renal blood flow, during cyst formation, and after kidney injury. We will evaluate how changes in cilia behavior under different conditions influence Ca2+, Stat6, and mTor signaling activity and whether cilia morphology, length, or behavior is altered during cyst formation. Importantly, all of these studies will be performed in the kidney of a live mouse. Results will provide novel insights into how the cilium functions in the kidney and how defects in cilia are possibly involved in diseases.

Support or Funding Information

P30DK074038R01DK065655
Preclinical Evaluation of the Phosphodiesterase‐4 Inhibitor, Rolipram, in an Infant Model of Sepsis‐Induced Cardiorenal Syndrome
Authors: Sims Clark R , Singh Sharda P , Mayeux Philip R
Published: November 2023

Multi‐organ failure is a frequent complication of infant sepsis. Sepsis‐induced cardiorenal syndrome (type 5), defined as development of acute cardiac dysfunction and acute kidney injury, is a frequent complication of infant sepsis that dramatically increases mortality. Septic shock in adults typically presents as a hyperdynamic state with high cardiac output and low systemic vascular resistance. However, most infants with septic shock show low cardiac output and high systemic vascular resistance (cold shock). To define the apparently unique pathogenic mechanisms contributing to renal and cardiac failure during septic shock in infants, and identify targeted therapies to reverse them, we developed a rat pup (17–19 days old) model of infant cardiorenal syndrome induced by cecal ligation and puncture (CLP), a model of infant sepsis that replicates the key cardio‐renal abnormalities. Rolipram is a phosphodiesterase‐4 inhibitor shown to reduce renal vascular resistance and improve microvascular perfusion in an adult mouse model of sepsis. The therapeutic potential of rolipram was evaluated using intravital video microscopy (IVVM) and echocardiography at specific time points following CLP in our rat pup model. A dose‐finding study was completed using IVVM at 6h following CLP that showed that a dose of 0.1 mg/kg, administered at the time of CLP, protected the pups from sepsis‐induced renal hypoperfusion. This dose was then used in further studies. At 18h following CLP, the single dose of rolipram administered at the time of CLP still prevented renal hypoperfusion and also prevented sepsis‐induced decline in stroke volume, left ventricular velocity, fractional shortening, ejection fraction, and most importantly, cardiac output as measured by echocardiography. Rolipram was also able to prevent the increase in blood urea nitrogen, which is used clinically to assess renal function. The protection by rolipram on perfusion and cardiac output indicate that rolipram may be therapeutically beneficial in infant cardiorenal syndrome.

Support or Funding Information

CRS supported by T32 GM106999, F31DK104533, AHA PRE20450050; PRM supported by AHA 15GRNT2508025 and UAMS Medical Research Foundation.
The role of the locus coeruleus in social stress‐induced inflammation
Authors: Finnell Julie E , Lombard Calliandra M , Fadel Jim R , Wood Chris S , Wood Susan K
Published: November 2023

Social stress is known to be a factor in the development of psychosocial disorders such as depression. The locus coeruleus (LC), the major source of norepinephrine (NE) to the brain, has been linked to the pathogenesis of depression; however the mechanism by which LC‐NE dysregulation promotes its development is not well understood. Inflammation has recently become a topic of interest in the study of depression, as increased inflammation in both the periphery and the brain have been linked to treatment resistant depression. We have previously shown that rats that develop anhedonic‐like behavior in response to social defeat have persistent increases in cytokine concentration and cytokine receptor expression. Interestingly, NE may play a role in stress‐induced inflammation as it is reported to promote a pro‐inflammatory state in the periphery, while evidence suggests that NE may serve to inhibit neuroinflammation in the CNS. Based on the role the LC‐NE system may play in stress regulation, the aim of this study was to determine the LC's involvement in stress‐induced inflammation and anhedonia. Male Sprague Dawley rats were injected with either vehicle or DSP‐4 (400 ug/rat, icv) to selectively lesion the NE projections from the LC one week prior to the start of social defeat or control exposure (30 min/5 days). 4 days after defeat or control, all rats (including control animals) were exposed to the sucrose preference test, followed 24 hours later by one single defeat (30 min). Immediately after the defeat stress animals were sacrificed to collect brain and plasma. Cytokine expression in plasma and brain tissue was determined using a Bio‐Plex (Bio‐Rad) and NE levels were assessed using HPLC. In agreement with our previous findings, vehicle treated rats which developed anhedonic‐like behavior in response to a history of social defeat exhibited greater neuro‐inflammation as compared to those with a history of control exposure. Treatment with DSP‐4 effectively reduced the concentration of NE within several stress‐related brain regions, likely hindering NE's anti‐inflammatory effect in the CNS during social defeat exposure. Interestingly, DSP‐4 did not protect against the development of an anhedonic‐like phenotype. In addition, our results show that re‐exposure to social defeat resulted in a sensitized immune response in rats with a history of social defeat and that a DSP‐4‐induced LC lesion drastically reduced stress‐induced cytokine release in plasma. These data confirm that during social stress exposure, LC‐NE projections contribute to the peripheral cytokine response. Together these data suggest that the LC plays a prominent role in stress‐induced inflammation, and that neuro‐inflammation may be a key factor in the development of depressive behavior and may serve as a target for the treatment of depression.

Support or Funding Information

Research supported by 15SDG22430017 and P20GM103641.
Immunogenetic role of G Protein Signaling Modulator 3 (GPSM3) in the pathogenesis of rheumatoid arthritis
Authors: Gall Bryan J , Schroer A B , Gross J D , Stoilov P , Setola V , Watkins C M , Siderovski D P
Published: November 2023

Rheumatoid arthritis (RA) is a chronic and debilitating disease mediated by dysregulated recruitment and activation of immune cells. G Protein Signaling Modulator 3 (GPSM3) is restricted in its expression to leukocytes, with its greatest expression occurring in monocytes and neutrophils ‐‐ cell lineages paramount to RA pathogenesis. Notably, two human GPSM3 single‐nucleotide polymorphisms (SNPs) are associated with a decreased likelihood of developing RA. We found that whole blood mRNA isolated from volunteers homozygous for these two ‘protective’ GPSM3 SNPs (n = 11) contained on average 24% less GPSM3 transcript than did whole blood from volunteers without the SNPs (n = 58). In vitro reporter gene expression data derived from the cloned promoter region of the human GPSM3 gene suggest that the minor GPSM3 SNPs are associated with a decrease in promoter activity that explains the entirety of the SNPs’ effect on GPSM3 transcription in whole blood. Functionally, we show that GPSM3‐deficient human monocyte‐like and neutrophil‐like cell lines each exhibit disruption in real‐time, chemokine‐induced migration. From these data, we conclude that the ‘protective’ GPSM3 SNPs result in decreased transcript abundance in vivo, which likely results in decreased GPSM3 protein expression as well—a hypothesis we are presently testing. GPSM3 may thus play a role in the migration of proinflammatory leukocytes, such as neutrophils and monocytes, to synovial tissues during RA inflammatory bouts. We envisage a model wherein GPSM3 expression facilitates migratory signaling, and that either ‘decrease‐of‐function’ SNPs or ‘loss‐of‐function’ mutations perturb this facilitation. As a result, invasion into synovial tissue is decreased when GPSM3 levels are decreased.

Support or Funding Information

This work was supported in part by the National Institutes of Health under Award Number U54GM104942.
β2‐Adrenergic Receptors Regulate Innate Immune Responses Through β‐Arrestin Dependent Pathways
Authors: Grisanti Laurel A , Gorsky Joshua , Repas Ashley A , Gao Erhe , Carter Rhonda L , Rabinowitz Joseph E , Benovic Jeffrey L , Koch Walter J , Tilley Douglas G
Published: November 2023

Following myocardial infarction (MI), inflammatory responses are important for initiating and regulating cardiac remodeling and tissue repair. Previous work in our lab has shown the importance of β2‐adrenergic receptors (β2AR) in regulating inflammatory responses through decreasing CCR2 expression and increasing splenic retention of leukocyte populations, resulting in decreased leukocyte infiltration to the damaged heart. Using chimeric mice that lack β2AR expression only on cells of hematopoietic origin we demonstrated that lack of β2AR expression in BM resulted in 100% mortality from cardiac rupture within two weeks of receiving MI, in contrast to their WT counterparts that had ~20% death. Administration of β2AR agonists in vitro and in vivo increased CCR2 expression and BM migration while β2AR antagonists decreased CCR2 expression and increased splenic leukocyte retention in vivo. Use of pepducins as allosteric modulators of β2AR signaling demonstrated the importance of β‐arrestin‐mediated signaling in increasing CCR2 expression and responses, which was confirmed in β‐arrestin KO BM. Furthermore, use of mutant β2AR constructs that are capable of signaling only through Gαs or β‐arrestin dependent pathways confirmed the importance of β‐arrestin signaling in altering CCR2 levels. These results demonstrate the critical role of β2AR‐mediated β‐arrestin signaling in the regulation of CCR2 expression on hematopoietic cells and its importance in mounting an immune response to promote healing following acute cardiac injury.

Support or Funding Information

This work was supported by NIH grants HL105414 (to D.G.T.), HL091799 (to W.J.K.), and an AHA postdoctoral fellowship (to L.A.G.).
Acetylcholine Released by the Endothelium Mediates Flow‐induced Endothelial Ca2+ Signalling and Vascular Relaxation
Authors: Wilson Calum , Sanchez‐Santos Manuel , McCarron John G
Published: November 2023

The flow of blood generates mechanical forces (e.g. shear‐stress) that are important physiological regulators of vascular tone. The vascular endothelium senses these forces and, in response, releases various vasodilators (e.g. nitric oxide) that relax smooth muscle cells in a process termed flow‐mediated vasodilation. Whilst some elements of the signalling mechanisms have been identified, precisely how flow is sensed and then transduced to cause the release of relaxing factors is poorly understood. In intact, pressurized arteries we show that flow induces relaxation of phenylephrine‐induced contractions. In large areas of the endothelium of surgically opened arteries, encompassing ~150 cells, flow (shear‐stress: 3 dyne cm−2) induced endothelial Ca2+ signalling and the release of nitric oxide. The Ca2+ signals were complex and transmitted between cells as intercellular “waves”, resulting in spatiotemporally heterogeneous activity across the endothelium. The Ca2+ signals were evoked both by IP3‐mediated Ca2+ release and Ca2+ influx from the extracellular space. Both components of the Ca2+ signals (release and influx) arose from the activation of the endothelium by acetylcholine (ACh) released in response to shear‐stress. In support, flow‐induced Ca2+ signals were abolished by atropine and by acetylcholinesterase. The flow‐induced Ca2+ signals were also attenuated by the choline acetyltransferase inhibitor, bromoacetylcholine, and potentiated by the acetylcholinesterase inhibitor, neostigmine. Flow‐induced responses were also blocked by depolarization and by inhibitors of chloride channels, but were unaffected by inhibitors of ATP‐mediated signalling pathways, organic cation transporters, or Panx hemichannels. Together, these results suggest that physiological shear‐stress induced activation of endothelial chloride channels mediates the release of ACh and hence flow‐mediated vasodilation. Significantly, these results also suggest that ACh is an autocrine signalling molecule released from endothelial cells.

Support or Funding Information

Supported by the Wellcome Trust and the British Heart Foundation
Trimethylamine‐N‐Oxide, an Intestinal Microbial Metabolite Instigates NLRP3 Inflammasome Activation and Endothelial Dysfunction
Authors: Koka Saisudha , Xia Min , Chen Yang , Li Pin‐Lan , Boini Krishna M
Published: November 2023

Plasma trimethylamine‐N‐oxide (TMAO), a product of intestinal microbial metabolism of dietary phosphatidylcholine has been recently associated with atherosclerosis and increased risk of cardiovascular diseases (CVD) in rodents and humans. However, the molecular mechanisms of how TMAO induces atherosclerosis and CVD progression are still unclear. The present study tested whether TMAO induces NLRP3 inflammasome formation and activation and thereby contributes to endothelial injury initiating atherogenesis. Confocal microscopic analysis showed that TMAO treatment significantly increased the colocalization of NLRP3 with Asc or NLRP3 with caspase‐1 in endothelial cells (EOMA) compared to control group. Pretreatment with caspase‐1 inhibitor, YVAD abolished the TMAO‐induced inflammasome formation in these cells. Correspondingly, TMAO treatment significantly increased the caspase‐1 activity (2.2 folds) and IL‐1β production (1.8 folds) compared to control cells. The YVAD treatment significantly attenuated the TMAO‐induced caspase‐1 activity and IL‐1β production. Further, Western blot analysis showed that TMAO treatment significantly increased cleaved caspase‐1 level compared to control cells. In addition, TMAO treatment significantly increased the cell permeability of EOMA cell layers compared to control cells (Control: 1 ± 0.1 vs TMAO: 2 ± 0.07). However, pretreatment with YVAD attenuated TMAO‐induced cell permeability. In animal experiments, direct infusion of TMAO by osmotic pump implanted subcutaneously in mice with partially ligated left carotid artery were found to have significantly increased neo‐intimal formation, which correlated with increased IL‐1β production in the intima. In conclusion, the formation and activation of NLRP3 inflammasomes by TMAO may be an important initiating mechanism to turn on the endothelial inflammatory response leading to endothelial dysfunction and atherogenesis in mice.

Support or Funding Information

supported by NIH grants DK104031 and HL‐75316.
Upregulation of Hsp70 Protects the Lung Microvascular Endothelial Barrier from Pneumolysin Induced Injury
Authors: Li Xueyi , Chen Feng , Yan Fang , Wang Yusi , Haigh Stephen , Gorshkov Boris , Meadows Louise , Catravas John , Lucas Rudolph , Verin Alexander , Fulton David
Published: November 2023

Pneumonia is a leading cause of death in children and the elderly worldwide, accounting for 15% of all deaths of children under 5 years old. Despite optimal antibiotic therapies and supportive care, mortality remains unacceptably high. Streptococcus pneumonia is one of the most common and most aggressive causes of pneumonia and sepsis. The Gram positive toxin, pneumolysin (PLY), is released from the cytosol of compromised Streptococcus and plays a key role in the development of the extensive permeability edema that causes acute lung injury (ALI). The mechanism by which PLY disrupts the endothelial barrier is not fully understood and greater insight is needed to develop novel therapeutics to counter microvascular permeability and ALI. Previously we found that Hsp90 inhibitors significantly reduce the production of barrier disruptive reactive oxygen species (ROS) via inhibition of NADPH oxidase activity. The suppression of Hsp90 is accompanied by increased expression of Hsp70 and we revealed an unexpected but potent role of Hsp70 in suppressing ROS production. Therefore the goal of the current study was to identify whether the upregulation of Hsp70 is an effective strategy to protect the lung microvascular endothelial barrier from Gram positive bacterial toxins. Overexpression of Hsp70 via adenovirus decreased NOX‐derived ROS and was highly effective at preventing the PLY‐stimulated increases in permeability of human lung microvascular endothelial cells (HLMVEC) and limiting cytotoxicity. To acutely stimulate endogenous Hsp70 expression, we employed geranylgeranylacetone (GGA) an activator of HSF. After 4hrs treatment with GGA, HLMVECs exposed to PLY displayed improved cell viability and enhanced endothelial barrier function as measured by both Electric Cell‐substrate Impedance Sensing (ECIS) and transwell permeability assay compared to controls. In mice, GGA was administered IP and 4hrs later PLY was administered IT to disrupt lung microvascular function. Mice treated with GGA had significantly less Evans Blue Dye extravasation suggesting that the acute upregulation of Hsp70 may be an effective therapeutic approach in the treatment of lung injury associated with pneumonia.

Support or Funding Information

NIH, P01HL101902
Regulation of Fibronectin Gene Expression by Scleraxis
Authors: Czubryt Michael Paul , Lin Justin , Bagchi Rushita Adhikari , Wang Ryan
Published: November 2023

The glycoprotein fibronectin is a key component of the extracellular matrix (ECM), linking myriad ECM components such as collagen to one another as well as to cell surface integrins and contributing to basal tissue structure. Up‐regulation of fibronectin occurs in response to injury, and increased fibronectin expression is an important feature of pathological cardiac fibrosis, however the molecular regulators of this process are incompletely defined. We previously found that the transcription factor scleraxis regulates the expression of numerous ECM components, and that scleraxis is up‐regulated by pro‐fibrotic stimuli, thus our objective was to determine the effect of scleraxis on fibronectin expression. Transfection of NIH‐3T3 fibroblasts with scleraxis resulted in a three‐fold increase in fibronectin gene expression. In silico analysis of the human fibronectin gene promoter sequence revealed two putative E‐box sequences to which scleraxis may bind. Using chromatin immunoprecipitation assays, we confirmed the occupancy of these sites by scleraxis in human cardiac myofibroblasts, and demonstrated the ability of scleraxis to bind these E‐boxes using electrophoretic mobility shift assays. By luciferase gene reporter experiments, we found that scleraxis transactivates the fibronectin gene promoter. Site‐directed mutagenesis of single E‐boxes significantly reduced promoter transactivation, with complete abrogation of scleraxis‐mediated reporter activity when both E‐boxes were mutated. Our data demonstrates that scleraxis is a potent transcriptional regulator of fibronectin gene expression, reveals the mechanism by which this regulation is achieved, and suggests that scleraxis‐mediated fibronectin expression may contribute to fibrosis.

Support or Funding Information

Supported by the Canadian Institutes of Health Research (MOP‐136862 to MPC).
IL‐10 polarizes macrophages in vivo to an anti‐inflammatory phenotype to improve cardiac remodeling post‐myocardial infarction
Authors: Jung Mira , Ma Yonggang , Yabluchanskiy Andriy , Iyer Rugmani Padmanabhan , Lindsey Merry L
Published: November 2023

To evaluate the impact of aging on cardiac repair following myocardial infarction (MI), we enrolled 3–6 month old (young) and 18–23 month old (old) C57BL/6J mice. The mice were subjected to left coronary artery ligation and sacrificed at day 7 post‐MI. The survival rate was 38.9% for the young group and 77.8% for the old group. As excessive inflammatory response contributes to adverse remodeling of the left ventricle (LV) and mortality following MI, we evaluated inflammatory cell infiltration and macrophage polarization in the infarcted region. Histological analysis revealed the infiltration of macrophages in the old LV infarct was significantly lower than in young mice (p <0.05). We isolated macrophages from LV infarct region at day 7 post‐MI and assessed macrophage polarization by quantitative RT‐PCR. The M1 marker IL‐6 was significantly decreased and the M2 marker YM1 was significantly increased in the old mice (both p<0.05 vs. young). In the infarct LV, interleukin (IL)‐10 gene levels were higher in old than in young at day 7 post‐MI. To test whether IL‐10 explained the survival differences, young mice (n=21) were treated with IL‐10 (50 μg/kg/day) starting at day 1 post‐MI via osmotic mini‐pump and were sacrificed at day 7 post‐MI. IL‐10 treatment increased survival rate to 52.4%. IL‐10 treated mice showed improved LV function and decreased macrophage infiltration. Additionally, macrophages from IL‐10‐treated LV infarcts showed decreased M1 markers (CCL3, IFN‐γ, and TNF‐α) and increased M2 markers (Arg1 and Ym1). Our results indicate that in vivo IL‐10 polarizes macrophages to an anti‐inflammatory phenotype.

Support or Funding Information

This work was supported by the American Heart Association 14POST18770012, and 15SDG22930009, the National Institutes of Health 1R03EB009496, SC2HL101430, HHSN 268201000036C (N01‐HV‐00244), HL075360, P01HL051971, P20GM104357, and the Biomedical Laboratory Research and Development Service of the Veterans Affairs Office of Research and Development Award 5I01BX000505
The Effects of High Salt Intake on Endothelial‐Mediated Dilation and Constriction in the Vasculature
Authors: Bratcher Adrienne , Joshua Irving
Published: November 2023

Hypertension is a major health problem in the United States, where more than 50 million people have the condition. High dietary salt intake has been shown to contribute to the development of hypertension in the DOCA‐salt model. However, elevations in salt intake alone may cause significant changes in microvascular response to vasoactive drugs. Therefore, this study is focused on the determination that increased dietary salt intake alone will have a major effect on the sensitivity of microvessels/macrovessels exposed to various vasoactive agents. Male Sprague‐Dawley rats were fed a high salt diet (1.2% Na+) or a normal salt diet (0.4% Na+) for 2 and 4 weeks. Intravital microscopy was used to observe the response of arterioles in the rat cremaster. In vitro aortic rings were used to observe the responses of large conduit vessels. Blood pressures were similar for all groups studied. In vivo and in vitro studies involved dose responses to acetylcholine (ACH, endothelium‐dependent vasodilator), sodium nitroprusside (NP, endothelium‐independent vasodilator) and endothelin‐1 (endothelium‐derived vasoconstrictor). Aortic tissue levels of eNOS, iNOS and SOD were also observed by Western Blot Analysis. Our data suggests that the dilator and constrictor responses in the microvasculature are decreased. However, there appears to only be an increase in constrictor response and similar decrease in dilator response in the macrovasculature. Thus, impairment of the arteriolar and aortic responses due to increased dietary conditions could predispose rats to the development of hypertension. Our data also demonstrate that these alterations could be due to an increase in oxidative stress.
The Prenatal Renin‐Angiotensin System During a Critical Period in the Development of Hypertensive Heart Disease
Authors: Adetoro Isaiah A , Lucchesi Pamela Ann , Cismowski Mary , Berecek Kathleen , Bradford Chastity
Published: November 2023

Intrauterine and perinatal maternal stress increase the risk for cardiovascular disease in adult offspring. Upregulation of the renin‐angiotensin‐aldosterone system (RAAS) occurs early in the pathogenesis of hypertension and is associated with the initiation of a pro‐fibrotic myocardial environment. Our previous work with Spontaneously Hypertensive Rats (SHR) demonstrated that short‐term, prenatal and perinatal exposure of SHR dams to the angiotensin converting enzyme inhibitor (ACE1) captopril reduced hypertension and cardiac fibrosis in adult offspring. The goal of this study was to determine if these beneficial are associated with altered maternal imprinting of cardiac RAAS and its pro‐fibrotic targets. Cardiac lysates were prepared from normotensive WKY or SHR male offspring (14 day old) for analysis of RNA (qRT‐PCR) and protein (western blots, enzyme assays) content. AT1R receptor density was assessed by 125I‐Angiotesin II binding to isolated cardiac fibroblasts. Compared to WKY (n=5, p<0.05), ACE1 mRNA expression, tissue ACE1 activity and AT1R receptor density were significantly increased in SHR vs. WKY and were attenuated by maternal captopril treatment. The mRNA expression of anti‐fibrotic ACE2 and bradykinin type 2 receptor were also increased (P< 0.006) in SHR vs. WKY. Interestingly, there were no changes in the expression of other known RAAS targets, including transforming growth factor‐β, (TGF‐β), Col1a, Col3a, or connective tissue growth factor. Compared to WKY, both plasminogen activator inhibitor‐ 1, TGF‐β receptor II protein levels were decreased by ~80% (p<0.01), although mRNA expression was either unchanged or increased (1.32±0.08 fold, P<0.02), respectively. Taken together, these data suggest that in early stages of postnatal development, SHR cardiac RAAS up‐regulation is compensated by down‐regulation of known pro‐fibrotic targets and up‐regulation of the anti‐fibrotic ACE2 and BK2R. In conclusion, maternal captopril treatment may alter the epigenetic regulation of genes involved in the development and progression of hypertensive heart disease.

Support or Funding Information

NIH 2RO1‐HL5604‐12, Research Institute at Nationwide Children's Hospital (PAL) and start‐up funds Tuskegee College (CB)
Role of Thrombospondin 4 in Small Arteries in Hypertension
Authors: Palao Teresa , Rippe Catarina , van Bavel Ed , Bakker Erik NTP , Swärd Karl
Published: November 2023

Thrombospondin 4 (Thbs4) may have both intracellular and extracellular functions. As an extracellular matrix protein it may be important for its ability to bind proteins, thereby serving as an interaction platform in the extracellular matrix. In the cardiovascular system, Thbs4 expression is induced in the heart in response to hypertrophy or infarction injury. Intracellularly, it mediates the endoplasmic reticulum (ER) stress response in the heart by activating transcription factor 6α (Atf6α). A previous gene expression study by our group in resistance arteries of Spontaneously Hypertensive Rats (SHR) showed a 9‐fold upregulation of Thbs4 in hypertensive arteries. Here we explored the role of Thbs4 in small artery remodeling in hypertension.

Thbs4, Atf6α and ER stress response genes were analyzed at the gene expression level in the microarray data and determined at the protein level by western blot. To further study the role of Thbs4 in arteries in hypertension, wild type (WT) and Thbs4 knock out (KO) mice were treated with angiotensin II (Ang II) and resistance arteries were studied by pressure and wire myography. The ultrastructure of the arterial wall was studied with electron microscopy.

The microarray analysis showed an upregulation of ER‐stress response genes associated with Thbs4 in SHR arteries. At the protein level, Thbs4, Atf6α and two of its target genes were upregulated in SHR vs control. Ang II treated WT mice showed impaired endothelial dependent relaxation, which was not seen in Ang II‐treated KO mice or in the untreated controls. No differences were found in the passive pressure‐diameter curves. However, the stress‐strain relationships of the arteries showed that the Ang II treated KO mice were less stiff, associated with thicker diameters of the collagen fibers as revealed by electron microscopy.

Taken together, the results indicate the activation of the ER stress response in small arteries during hypertension. ER stress and Thbs4 may play a role in impaired endothelial dependent relaxation in arteries in hypertension. In addition, Thbs4 might also be involved in the changes in the ultrastructure of the arterial wall, leading to changes in the stiffness of the vessels.

Support or Funding Information

funded by the European Union's Seventh Framework Programme for research, technological development and demonstration under grant agreement no 606998.
Inhibition of neutrophil chemotaxis by N‐Acetyl‐Seryl‐Aspartyl‐Lysyl‐Proline and thymosin β4
Authors: Nakagawa Pablo , Xu Jiang , Bordcoch Ginette , Janic Branislava , Carretero Oscar A
Published: November 2023

The role of neutrophils in heart failure has been extensively analyzed and it has been shown that they are the first cells that massively invade the myocardium after myocardial infarction (MI). N‐Acetyl‐Seryl‐Aspartyl‐Lysyl‐Proline (Ac‐SDKP) is a natural tetrapeptide that is released from its precursor thymosin β4 (TB4). Ac‐SDKP and TB4 are shown to have beneficial effect in post MI cardiac healing by decreasing cardiac rupture and mortality in mice. Therefore we explored whether neutrophils play a role in the mechanism of AcSDKP and TB4 cardiac protection. We hypothesized that Ac‐SDKP and TB4 contribute to heart healing in MI by inhibiting neutrophil chemotaxis.

To test neutrophil chemotaxis we performed transwell chemotaxis assay using neutrophil differentiated HL‐60 cells. We measured the migration of a) vehicle, b) Ac‐SDKP (10, 100 nM), or c) TB4 (20 nM) pre‐treated cells towards to a chemotactic bacterial formylated tripeptide N‐formyl‐met‐leu‐phe (fMLP) at 1nM. We also measured the effect of Ac‐SDKP on neutrophil infiltration post‐MI in mice. Ac‐SKDP or vehicle were infused subcutaneously using osmotic minipumps at a dose of 1.6 mg/kg/day. Two days after minipump implantation, MI was induced by permanent ligation of the left descending coronary artery. Neutrophil infiltration was measured at 24 hrs post‐MI by immunohistochemistry.

At a dose of 100 nM Ac‐SDKP reduced fMLP‐induced neutrophil chemotaxis by 20 %. However, at 10 nM Ac‐SDKP failed to inhibit neutrophil chemotaxis. TB4 at 20 nM completely inhibited neutrophil migration. In vivo, Ac‐SDKP decreased neutrophil cardiac infiltration (veh: 44 vs Ac‐SDKP: 13 cells/mm2; p < 0.05).

We conclude that TB4 is a potent inhibitor of neutrophil chemotaxis, while Ac‐SDKP exerts mild inhibitory effects. Inhibition of neutrophil chemotaxis could explain some of the beneficial effects of Ac‐SDKP and TB4 in post MI cardiac inflammation and fibrosis.

Support or Funding Information

Supported by NIH HL028982 and AHA 13PRE17100074
Role of ACE2 in the Cardioprotective Effects of Angiotensin II Type 2 Receptors
Authors: Zhu Liping , Xu Jiang , Harding Pamela , Yang Xiao‐Ping
Published: November 2023

Blockade of angiotensin II (Ang II) type 1 receptors with angiotensin receptor blockers (ARBs) activates the Ang II type 2 receptors (AT2) and also increases angiotensin‐converting enzyme 2 (ACE2) expression and Ang 1–7 levels. However, it is not known whether activation of AT2 and ACE2 are synergistically associated to exert cardioprotection. We hypothesize that activation of AT2 increases the expression and activity of ACE2, leading to cardioprotection. Transgenic mice with cardiac overexpression of AT2 (Tg‐AT2) were subjected to myocardial infarction (MI) for 12 weeks. We found that Tg‐AT2 mice had cardiac ACE2 protein expression 2.36±0.07‐fold higher than the wild‐type (WT) controls, associated with better preserved cardiac function compared with WT controls (ejection fraction: 41.6±2.3% vs 27.6±1.8%). In AT2‐stimulated coronary artery endothelial cells, ACE2 protein expression was increased by 1.79±0.04‐fold and ACE2 activity was enhanced from 0.61± 0.05 (basal) to 0.95±0.03 pg/μl/h/μg protein. These effects were blunted by AT2 antagonist. Furthermore, activation of AT2 increased cGMP by 1.71±0.12‐fold, which was diminished by Mas receptors antagonist. AT2 activation also increased Ang 1–7 from 0.1±0.05 (basal) to 15.6±0.5 (pg/ml/μg protein) and this effect was diminished by the AT2 antagonist. Our data suggest that the cardioprotective effects of AT2 is in part mediated via activation of ACE2, enhancing the release of Ang 1–7 and leading to cardioprotection.
Analysis of phosphorylation of the myosin targeting subunit of smooth muscle myosin light chain phosphatase by Phos‐tag SDS‐PAGE
Authors: Walsh Michael P. , MacDonald Justin A. , Sutherland Cindy
Published: November 2023

Phosphorylation of the myosin targeting subunit (MYPT1) of myosin light chain phosphatase plays an important role in the regulation of smooth muscle contraction, and several sites of phosphorylation by different protein Ser/Thr kinases have been identified. Furthermore, in some instances, phosphorylation at specific sites affects phosphorylation at neighboring sites, with functional consequences. Characterization of the complex phosphorylation of MYPT1 in tissue samples at rest and in response to contractile and relaxant stimuli is, therefore, challenging. We have exploited Phos‐tag SDS‐PAGE in combination with western blotting using antibodies to MYPT1 to separate multiple phosphorylated MYPT1 species and quantify MYPT1 phosphorylation stoichiometry using purified, full‐length recombinant MYPT1 phosphorylated by Rho‐associated coiled‐coil kinase (ROCK) and cyclic AMP‐dependent protein kinase (PKA). This approach confirmed that phosphorylation of MYPT1 by ROCK occurs at Thr697 and Thr855, PKA phosphorylates these two sites and the neighboring Ser696 and Ser854, and prior phosphorylation at Thr697 and Thr855 by ROCK precludes phosphorylation at Ser696 and Ser854 by PKA. Furthermore, phosphorylation at Thr697 and Thr855 by ROCK exposes two other sites of phosphorylation by PKA. Treatment of Triton‐skinned rat caudal arterial smooth muscle strips with the membrane‐impermeant phosphatase inhibitor microcystin, or of intact tissue with the membrane‐permeant calyculin A, induced slow, sustained contractions that correlated with phosphorylation of MYPT1 at 7 to ≥10 sites. Phos‐tag SDS‐PAGE thus provides a suitable and convenient method for analysis of the complex, multi‐site MYPT1 phosphorylation events involved in the regulation of myosin light chain phosphatase activity and smooth muscle contraction.

Support or Funding Information

Funded by the Canadian Institutes of Health Research (MOP‐111262)
Rab25 stimulates functional CaV1.2 channel surface expression in arterial smooth muscle cells
Authors: Bulley Simon , Bannister John P , Leo Marie Dennis , Williams Brent , Jaggar Jonathan H
Published: November 2023

Plasma membrane‐localized CaV1.2 channels are the primary calcium (Ca2+) influx pathway in arterial smooth muscle cells (myocytes). CaV1.2 channels regulate several cellular functions, including contractility and gene expression, but trafficking pathways that control the surface expression of these proteins are unclear. Similarly, expression and physiological functions of small RabGTPases, proteins that control vesicular trafficking in arterial myocytes are poorly understood. Here, using Western blotting and immunoFRET we show that Rab25, a GTPase previously associated with apical recycling endosomes, is expressed in cerebral artery myocytes. Immunofluorescence resonance energy transfer (immunoFRET) microscopy indicated that Rab25 locates in close spatial proximity to CaV1.2 channels in myocytes. Rab25 knockdown using siRNA reduced surface CaV1.2 abundance in arteries, as determined using arterial surface biotinylation. In contrast, CaV1.2 was not located nearby Rab11A or Rab4 and CaV1.2 surface protein was unaltered by Rab11A or Rab4A knockdown. Rab25 knockdown resulted in CaV1.2 internalization and degradation by a mechanism involving both lysosomal and proteasomal pathways. Rab25 knockdown also reduced whole‐cell CaV1.2 current density in myocytes and depolarization (20–60 mM K+) and pressure‐induced vasoconstriction in cerebral artery segments. These results show that Rab25 is expressed in arterial myocytes and describe a physiological function of this protein. Rab25 promotes CaV1.2 channel surface expression in arterial myocytes to stimulate vasoconstriction.

Support or Funding Information

This work was supported by National Heart, Lung and Blood Institute Grants R01 HL67061, HL094378 and HL110347 to J. H. Jaggar and American Heart Association Scientist Development Grant to M. D. Leo.
Resting tension is important for the contractile response but not to vasodilatation in renal hypertensive rat aorta
Authors: Bendhack Lusiane Maria , Silva Bruno Rodrigues , Grando Marcella Daruge
Published: November 2023

Nitric oxide (NO) produced by the NO‐Synthase (NOS) controls vascular tone and systemic arterial pressure. Shear stress‐mediated phosphorylation of NOS regulates NOS activity. Phosphorylation of Ser1177 (P‐Ser) activates NOS and Thr495 (P‐Thr) inactivates NOS. Protein kinase Akt/PI3K and c‐Src are enzymes that can phosphorylate these residues, but the signaling in renal hypertensive (2K‐1C) rat aorta submitted to increasing resting tension is not known. This study aimed to evaluate the effects of the resting tension of 1.5 g (control) and 3.0 g on the eNOS phosphorylation in phenylephrine (PE)‐induced contractile response in isolated 2K‐1C rat aorta. Concentration‐effect curves for PE were constructed in aortas under resting tension of 1.5 g and 3.0 g in the absence or presence of NOS inhibitor (L‐NAME, 100 μM). On the top of maintained contraction to PE, concentration‐effect curves for acetylcholine (ACh) were constructed. The expression of P‐Ser and P‐Thr were evaluated by Western Blot. The maximum effect induced by PE on resting tension of 1.5 g was lower in 2K‐1C (1.2 ± 0.2g, n=7; p<0.001) than in normotensive 2K (2.2 ± 0.1g; n=5). This effect was normalized by NOS inhibition with L‐NAME. Both P‐Ser and P‐Thr expressions were higher in 2K‐1C than in 2K aortas. In 2K‐1C the increased P‐Ser was inhibited by PI3K/Akt inhibitor (wortmannin, 20 μM) and the increased P‐Thr was inhibited by c‐Src inhibitor (PP1, 10 μM). Under resting tension of 3.0 g, PE‐induced contractile response was similar in 2K‐1C and 2K aortas. Increased resting tension from 1.5 g to 3.0 decreased P‐Ser and increased P‐Thr in 2K aorta, but it was not modified in 2K‐1C aorta. ACh‐induced relaxation was lower in 2K‐1C (81.4 ± 4.7%; n=7; p<0.001) than in 2K (100.5 ± 2.4%; n=5), that was not modified under 3.0 g resting tension in 2K and 2K‐1C. Taken together, our results demonstrate that the increasing resting tension from 1.5 g to 3.0 g decreases eNOS phosporylation in the activation site (P‐Ser) in 2K rat aorta. The anti‐contractile effect induced by PE in 2K‐1C rat aorta under 1.5 g tension is due to eNOS activation in a PI3K/Akt dependent way. The anti‐contractile effect is abolished by increasing the resting tension to 3.0 g due to P‐Thr in a c‐Src dependent way. These results indicate that resting tension is important for the contractile response, but not to vasodilatation in renal hypertensive (2K‐1C) rat aorta.

Support or Funding Information

Supported by FAPESP, CNPq and CAPES.
Circadian rhythms in leukocyte recruitment to tissues
Authors: Scheiermann Christoph
Published: November 2023

Leukocyte recruitment from blood to tissues is a critical step of the immune system to protect against pathogens and provide tissue repair. While myeloid cell recruitment is a hallmark in inflammatory conditions, lymphocyte recirculation through tissues is an important feature of immune surveillance of an organism at steady‐state. Thus far, various molecules have been implicated in these migratory processes including chemokines and adhesion molecules. However, how this fundamental process of immunity is being regulated at the organismal level at different times is unknown. Here, we describe mechanisms that govern a non‐continuous but oscillatory behavior in the infiltration of myeloid and lymphoid cells to different tissues in the mouse. We screened multiple adhesion molecules and chemokine receptors on various leukocyte subpopulations in addition to molecules expressed by endothelial cells in vascular beds of multiple organs. Our data indicate the existence of a leukocyte‐ and tissue‐specific oscillatory molecular signature in the expression of pro‐migratory factors. Specifically, we present data demonstrating that robust circadian oscillations, exhibiting a period length of ~24h, occur in cellular numbers in murine lymph nodes, showing a ~2‐fold difference with a trough at the onset of the behavioral rest phase (light) and a peak at the onset of the active phase (dark). Oscillations were observed in the capacity of lymphocytes to home to lymph nodes, peaking at the onset of the activity phase. Using lineage‐specific genetic ablation of circadian rhythmicity in T and B cells we demonstrate this to be dependent on both lymphocyte and endothelial oscillations in cell surface receptors. We detected similar oscillations in the capacity of lymphocytes to exit lymph nodes, exhibiting a ~3‐fold difference in the amount of cells in efferent lymphatic vessels. Egress could be modulated in a rhythmic manner acutely by pharmacological interventions as well as chronically with the help of lymphocyte‐specific genetic approaches. Taken together, our data show discrete tissue and leukocyte mechanisms that control rhythmic leukocyte recruitment to organs and provide new insights into the temporal control of innate and adaptive immunity.

Support or Funding Information

Funded by the European Research Council (CIRCODE) and the German Research Foundation (Emmy Noether SCHE 1645/2‐1 and SFB914 projects B09 and Z03).
Matrix Metalloproteinase‐12 Reduces Cardiac Dilation Post‐Myocardial Infarction by Decreasing Neutrophil Accumulation
Authors: Iyer Rugmani Padmanabhan , de Castro Brás Lisandra E , Jung Mira , Ma Yonggang , DeLeon‐Pennell Kristine Y , Flynn Elizabeth R , Cannon Presley L , Cates Courtney A , Lindsey Merry L
Published: November 2023

Early inhibition of matrix metalloproteinase‐12 (MMP‐12) worsens cardiac remodeling post‐myocardial infarction (MI), suggesting a beneficial role for MMP‐12. This study assessed whether exogenous MMP‐12 delivery early post‐MI is an effective therapeutic approach. Male C57BL/6J mice (3–6 months old, n=3/group) were subjected to left coronary artery ligation. Saline or active MMP‐12 (aMMP‐12; 0.5mg/kg/day) infusion was initiated at 3h post‐MI using an osmotic mini‐pump. Mice were sacrificed at day (d) 1 or 5 post‐MI. D0 (no MI) served as a negative control. Infarct areas were similar among saline and aMMP‐12 groups at both d1 and d5 (p=0.76 by ANOVA), indicating similar ischemic injury. Survival rates were not significantly different (p=0.38 at d1, p=0.45 at d5). End diastolic volume (EDV) increased in the saline group, and this increase was attenuated in aMMP‐12 (d0= 45±1 μl, saline= 117±4 μl, aMMP‐12= 85±4 μl). At d1 post‐MI, 12 pro‐inflammatory genes were reduced in the aMMP‐12 group (all p<0.05 vs. saline), including Il8rb, Il‐18, Tgf‐β1, and Tnf. Consistent with cytokine levels, neutrophils were reduced in the aMMP‐12 group by 60% at d1 and by 130% at d5 post‐MI (both p<0.05 vs respective saline groups). Neutrophil removal occurs mainly via apoptosis, and we observed a 4‐fold increase in cleaved caspase‐3 in the aMMP‐12 group at d1 and a 2‐fold increase at d5 post‐MI, compared to respective saline groups (all p<0.05). Our results revealed that MMP‐12 plays a cardioprotective role early post‐MI by attenuating neutrophil infiltration and enhancing neutrophil removal to reduce inflammation and LV dilation.

Support or Funding Information

This work was supported by the American Heart Association 14POST18770012, 14SDG18860050 and 15SDG22930009, the National Institutes of Health 1R03EB009496, SC2HL101430, HHSN 268201000036C (N01‐HV‐00244), HL075360, P01HL051971, P20GM104357, and the Biomedical Laboratory Research and Development Service of the Veterans Affairs Office of Research and Development Award 5I01BX000505