bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Role of Leptin in Coronary Collateral Growth
Authors: Graham Kathleen , Ohanyan Vahagn , Enrick Molly , Kolz Christopher , Chilian William M. , Yin Liya 
Published: November 2023

Leptin is an adipokine that is conventionally thought to have its major effects on appetite suppression, but more recently it is suggested to have a variety cardiovascular effects including on vascular growth. The Zucker obese fatty (ZOF) rat is a model of dysfunctional leptin signaling due to a mis‐sense mutation of the leptin receptor. This mutation leads to hyperphagia inducing dietary‐induced obesity and phenotypes consistent with the metabolic syndrome, e.g., obesity, hypercholesterolemia, hyperglycemia, and hyperlipidemia. Previously we observed abrogated coronary collateral growth (CCG) in ZOF rats, but we did not determine if this deficiency is directly due to the mis‐sense mutation in leptin, which could negatively impact the vasculature, or indirectly related to the hyperphagia‐induced metabolic syndrome. To resolve between these two possibilities, we studied CCG in young ZOF rats prior to the development of obesity and the alterations in blood chemistries. CCG was stimulated by repetitive episodes of myocardial ischemia (RI) induced by chronic implantation of a pneumatic snare around the left anterior descending artery (LAD), which was performed during a left thoracotomy. Pressurization of the snare induced occlusion of the LAD and a total of 24 occlusions were performed throughout the day. CCG in rats was assessed by the measurement of myocardial blood flow (MBF) using contrast echocardiography at Day 0 (prior to the initiation of RI) and after 10 days of RI in the normal and collateral‐dependent regions; and is presented as a ratio of collateral zone/normal zone flow (CZ/NZ). In old (6–9 months, n=8) and young (3–4 months, n=4) ZOF rats, the CZ/NZ ratios at Day 0 were 0.15±.03, and 0.22±0.04, respectively (P=NS). This indicates that the native collateral circulation was comparable in the two groups. In contrast, following 10 days of RI, the CZ/NZ flow ratio was unchanged (from Day 0) in the old ZOF rats (0.17±0.05), but significantly increased in the young ZOF rats (0.78±0.07; P<0.05 vs Day 0 and old ZOF). To eliminate the possibility that the differences are related to the ages of the ZOF rats, age‐matched Lean controls were studied. The CZ/NZ ratios were equal in the young and old lean rats suggesting that the difference in the ZOF rats is not related to age. Based on these results we conclude that the reason why CCG is impaired in ZOF rats is not due to an absence of leptin signaling; rather the impaired coronary collateral growth in ZOF rats is likely related to the myriad cardiovascular risk factors associated with the metabolic syndrome.Support or Funding InformationThis work was supported by NIH/NHLBI (HL100828Z and HL83366), Fibus Family Foundation, Frances Schermer Charitable Trust & The Lillian Schermer Charitable Trust, and the Joy Cone Company to W.M.C.; NIH/NHLBI (HL115114) to LY.
Neutrophil Extracellular Traps Contribute To Endothelial Barrier Dysfunction During Sepsis
Authors: Meegan Jamie E , Beard Richard S , Yang Xiaoyuan , Reynolds Jason J , Coleman Danielle C , Jannaway Melanie , Yuan Sarah Y 
Published: November 2023

Neutrophil extracellular traps (NETs) are DNA‐webs containing histones and granular enzymes produced by neutrophils during host defense against infection. It is becoming increasingly apparent that circulating NETs exacerbate tissue injury associated with inflammation. The purpose of this study was to determine the effects of NETs on endothelial barrier function. We identified increased markers of NETs in the lung and plasma of mice subjected to polymicrobial septic injury induced by cecal ligation and puncture. In an intravital microscopic analysis of microcirculation, NETs were found in mesenteric microvessels in response to fMLP stimulation. In cultured endothelial cell monolayers, treatment with NETs produced by activated human neutrophils induced barrier dysfunction as indicated by reduced transendothelial electrical resistance and increased albumin transendothelial flux. Exogenous histones produced a similar effect on barrier dysfunction. Immunofluorescence confocal microscopy indicates the involvement of conformational changes in adherens junction proteins VE‐cadherin and β‐catenin as a potential mechanism underlying NET‐induced barrier dysfunction. Furthermore, myosin light chain phosphorylation in endothelial cells was observed after NET stimulation, supporting the involvement of cytoskeleton response in this process. Taken together, the data suggest NETs may contribute to endothelial barrier dysfunction during inflammatory response associated with neutrophil activation.Support or Funding InformationThis work is supported by NIH RO1s HL126646, HL070752, and GM097270.
Super resolution imaging visualized the nanoscaled localization of integrin activation during human neutrophil arrest
Authors: Fan Zhichao , Kiosses William Bill , Ley Klaus 
Published: November 2023

Adhesion on vascular endothelium is the vital step for leukocyte recruitment and inflammation. Neutrophil is the most abundant leukocyte and is essential for innate immunity and inflammation. The activation of beta2 integrin is critical for neutrophil adhesion. Integrins are bidirectional signaling molecules that are bent at rest. Upon cell activation, integrins can extend (E+) and acquire a high affinity conformation with an “open” headpiece (H+). The canonical “switchblade” model of integrin activation proposes that the E+ conformation precedes H+, and the two are thought to be structurally linked. Only the E+H+ conformation can mediate cell adhesion by binding to ligand in trans. In our previous study, we found out an unexpected bent‐open (E−H+) conformation and an alternative allosteric pathway, which integrin can H+ prior to E+, during human neutrophil arrest. However, the resolution of our previous quantitative dynamic footprinting (qDF) microscopy is limited by optical diffraction limit (~300nm) that we cannot accurately observe the conformation of signal integrin, which is under nanoscale (~20nm). By combining stochastic optical reconstruction microscopy (STORM) with our qDF microscopy, we acquired nanoscale super‐resolution images of integrin activation on arrest human neutrophils. These images confirmed our finding that E−H+ integrin exist and brought us the accurate number and precise local distribution of E−H+, E+H− and E+H+ integrins on arrest neutrophils. We found out that E+H+ integrins are mostly located in microvilli tips and form microscale clusters to support neutrophil arrest.Support or Funding InformationThis research was supported by funding from the National Institutes of Health, USA (NIH, HL078784) and WSA postdoctoral fellowship from the American Heart Association, USA (AHA, 16POST31160014).
Angiotensin II‐preconditioning is associated with increased PKCɛ/PKCδ ratio and prosurvival kinases in mitochondria
Authors: Nuñez Rebeca , Javadov Sabzali , Escobales Nelson 
Published: November 2023

Recent studies indicate that angiotensin II replicates the cardioprotective effects of ischemic preconditioning (IPC). However, the cellular mediators of angiotensin II preconditioning (APC) remain to be fully understood. In this study, Langendorff‐perfused rat hearts were subjected to IPC, APC or both (IPC/APC) followed by ischemia‐reperfusion (IR), to determine the protein expression of PKCɛ, PKCδ, Akt, Erk1/2, JNK, p38 MAPK and GSK‐3β in mitochondria, and the permeability transition pore (mPTP) opening. IPC, APC and IPC/APC increased the percent recovery of left ventricular developed pressure (LVDP), and reduced lactate dehydrogenase (LDH) release compared to controls. These effects were associated with marked increases in the mitochondrial PKCɛ/PKCδ ratio, Akt, Erk1/2 and JNK levels and mPTP inhibition. GSK‐3β levels were unaffected by the treatment protocols. Chelerythrine (5 μM), a pan‐PKC inhibitor, abolished the enhancements of PKCɛ but increased PKCδ expression, and inhibited Akt, Erk1/2, and JNK protein levels. The drug however, did not affect cardioprotection by APC and IPC/APC. Losartan (10 μM), an angiotensin II type 1 receptor (AT1‐R) blocker, abolished the APC‐stimulated LVDP increase and inhibited the protein levels of PKCɛ, Akt, Erk1/2, JNK, and p38. Both drugs reduced ischemic contracture and LDH release, and abolished the inhibition of mPTP by the preconditioning protocols. These results suggest that the cardioprotection induced by APC and IPC/APC involves an AT1‐R‐dependent, translocation of PKCɛ and downstream survival kinases to the mitochondria leading to mPTP inhibition. The observation of cardioprotection in chelerythrine‐treated hearts, suggests that reduced PKCɛ/PKCδ ratio might attenuate calcium overload and contracture‐induced damage at reperfusion.Support or Funding InformationThis study was supported by the NIH RCMI Program grant No. G12M007600, NHLBI grant SC1HL118669 (SJ), and the University of Puerto Rico.
Treatment with the mitochondrial antioxidant peptide SS‐31 rescues neurovascular coupling responses and cerebrovascular endothelial function and improves cognition in aged mice
Authors: Tarantini Stefano , Valcarcel‐Ares Marta Noa , Yabluchanskiy Andriy , Fulop Gabor , Hertelendy Peter , Gautam Tripti , Farkas Eszter , Sonntag William E. , Csiszar Anna , Ungvari Zoltan 
Published: November 2023

Moment‐to‐moment adjustment of cerebral blood flow (CBF) via neurovascular coupling has an essential role in maintenance of healthy cognitive function. In advanced age increased oxidative stress and cerebromicrovascular endothelial dysfunction impair neurovascular coupling, likely contributing to age‐related decline of higher cortical functions. There is increasing evidence showing that mitochondrial oxidative stress plays a critical role in a range of age‐related cellular impairments, but its role in neurovascular uncoupling remains unexplored. The present study was designed to test the hypothesis that attenuation of mitochondrial oxidative stress may exert beneficial effects on neurovascular coupling responses in aging. To test this hypothesis 24 month old C57BL/6 mice were treated with a cell permeable, mitochondria‐targeted antioxidant peptide (SS‐31; 10 mg/kg/day, i.p.) or vehicle for 2 weeks. Neurovascular coupling was assessed by measuring CBF responses (laser speckle contrast imaging) evoked by contralateral whisker stimulation. We found that neurovascular coupling responses were significantly impaired in aged mice. Treatment with SS‐31 significantly improved neurovascular coupling responses by increasing NO‐mediated cerebromicrovascular dilation, which was associated with significantly improved spatial working memory, motor skill learning and gait coordination. These findings are paralleled by the protective effects of SS‐31 on mitochondrial production of reactive oxygen species and mitochondrial respiration in cultured cerebromicrovascular endothelial cells derived from aged animals. Thus, mitochondrial oxidative stress contributes to age‐related cerebromicrovascular dysfunction, exacerbating cognitive decline. We propose that the antioxidant peptide SS‐31 should be considered for pharmacological microvascular protection for the prevention/treatment of age‐related vascular cognitive impairment (VCI).Support or Funding InformationThis work was supported by grants from the American Heart Association, the National Center for Complementary and Alternative Medicine, and the National Institute on Aging
Fibulin‐4 Is Important for Maintaining Vascular Wall Integrity in Large but Not Small Vessels
Authors: Halabi Carmen M , Lin Michelle , Broekelmann Thomas J. , Chu Mon‐Li , Mecham Robert P. 
Published: November 2023

Deficiency or insufficiency of Fibulin‐4 (FBLN4) in mice leads to abnormal elastic fiber formation in large vessels with consequent aneurysm formation and arterial tortuosity, while FBLN4 mutations in humans lead to autosomal recessive cutis laxa type 1B (ARCL 1B), a multisystem disorder characterized by inelastic skin, arterial tortuosity, aortic aneurysms, and pulmonary emphysema and thought to be the result of aberrant elastic fiber formation. We sought to determine the consequences of a disease‐causing mutation in FBLN4 (E57K) on the cardiovascular system and vascular elastic fibers in a mouse model of ARCL 1B. Fbln4E57K/E57K mice were hypertensive and developed arterial elongation, tortuosity and ascending aortic aneurysms. Smooth muscle cell (SMC) organization within the wall of conduit arteries was abnormal and elastic fibers were fragmented and had a spongy, moth‐eaten appearance. Surprisingly, elastin and SMCs in the mesenteric, saphenous, and renal arteries of homozygous mutant mice were normal and seemingly unaffected by the E57K mutation. Furthermore, elastin and collagen content of large and small arteries were unchanged in Fbln4E57K/E57K mice. While the E57K mutation did not affect Fbln4 mRNA expression, FBLN4 protein levels were reduced in Fbln4E57K/E57K ascending aorta, but unchanged in mesenteric arteries. These results suggest a differential role for FBLN4 in elastic fiber assembly between elastic and muscular arteries. Future studies investigating tissue‐specific elastic fiber assembly may lead to novel therapeutic interventions for ARCL 1B and other disorders of elastic fiber assembly.Support or Funding InformationCMH is a Scholar of the Child Health Research Center at Washington University School of Medicine, National Institutes of Health (NIH) K12‐HD076224. She also received support from the NIH training grant 2T32HD043010‐11 and the Mallinckrodt Foundation Physician‐Scientist Training Program Fellow support. This work was funded by NIH grants R01‐HL53325 and R01‐HL105314 to RPM.
Ileal Smooth Muscle Thickness is Greater in Young Obese Zucker Rats
Authors: Burgess Andrea Rosalia , Trujillo Andrea Nichole , Barter Micaela , Breslin Jerome W 
Published: November 2023

Obesity is a risk factor for many pathologies including heart disease, type 2 diabetes and certain types of cancers. At this time little is known about how obesity effects the morphology of the small intestine or gut. The purpose of this study was to determine what morphological differences exist in the smooth muscle of the small intestine, between lean and obese Zucker rats. We hypothesized that the thickness of the circular and longitudinal muscle layers of the small intestine from obese Zucker rats would be greater compared to their lean counterparts. Ileum and jejunum from lean and obese Zucker rats were harvested, fixed in buffered formalin overnight, processed, and embedded in paraffin. Thin cross sections of the tissues were mounted on slides, stained with H&E followed by analyses of longitudinal and circular smooth muscle layer thicknesses using digital photos and FIJI/IMageJ software (version 1.5). Smooth muscle thickness data was exported from an Excel document and statistics performed utilizing GraphPad Prism (version 6.0). In addition, ileum from lean and obese Zucker rats was harvested, bisected lengthwise with the lacteals facing up, and fixed in 4% PFA overnight and then washed with sucrose solutions. The ileum tissues were pinned onto 6‐well silicone plates and strips of villi (1‐2 thick) were cut under a dissecting microscope. The villi strips were incubated with a LYVE‐1 antibody to identify lymphatic endothelial cells of the lacteals and a PECAM‐1 antibody to label microcirculation within the villi. Longitudinal and circular smooth muscle layers, identified in the ileum with H&E staining, were significantly thicker in 8‐week old obese Zucker rats compared to lean rats. No significant differences in smooth muscle thickness were observed in 12‐week or 26–32‐week old obese versus lean rats in either the ileum or the jejunum. Histological data obtained from the small intestine partially supports the hypothesis that intestinal smooth muscle layer thickness in obese juvenile Zucker rats was greater, but only at the 8‐week time point. Preliminary immunolabeling with LYVE‐1 positively identified the structure of the lacteal, while the PECAM‐1 labeling was strong within the microvasculature of the villi. Although additional studies with human tissue, e.g., samples derived from intestinal biopsies or surgical resection, are required to understand the biomedical significance of our findings, our data raise the possibility that for humans at a young age obesity may cause structural changes in the small intestine.Support or Funding InformationThis work was supported by an APS IOSP Undergraduate Summer Research Fellowship IOS‐1238831.
Thoracic Duct Lymph Suppresses the Release of Inflammatory Mediators from Macrophages in vitro
Authors: Castillo Rudy , Hodge Lisa 
Published: November 2023

The thoracic duct distributes a large pool of lymph rich in immune cells, inflammatory mediators and lipids to blood circulation. Recent literature suggests that during gastrointestinal injury, soluble factors in mesenteric lymph redistribute to the lung, via the thoracic duct, where they initiate inflammation and contribute to multiple organ dysfunction syndrome (MODS). Alternatively, normal mesenteric lymph has been shown to suppress inflammation in vivo and in vitro. Specifically, under inflammatory conditions, normal mesenteric lymph reduced the expression of cell adhesion molecules on endothelial cells and inhibited neutrophil apoptosis in vitro. However, the role of normal lymph on macrophage function remains unknown. Importantly, macrophages have been to shown to contribute to MODS. The purpose of this study was to investigate the effect of normal lymph on macrophage function. Specifically, we hypothesized that normal thoracic duct lymph (TDL) would suppress the release of inflammatory mediators by LPS‐activated macrophages.To test this hypothesis, under anesthesia the thoracic ducts of four mongrel dogs were cannulated and lymph was collected. The TDL was centrifuged to remove cells and the TDL supernatant was frozen at −80°C. Murine RAW 264.7 macrophages were cultured in vitro with TDL at 5% total volume per well with or without of lipopolysaccharide (LPS). Twenty‐four hours after incubation at 37°C with 5% CO2, culture supernatants were assayed for nitric oxide (NO) and tumor necrosis factor‐alpha (TNF‐a) production. Macrophage viability was measured using flow cytometry with the markers Annexin V and Propidium Iodide.TDL did not augment the production of NO, TNF‐a or alter cell viability by macrophages cultured in media alone. However, when macrophages were activated with LPS, TDL suppressed the release of NO and TNF‐a. Specifically, LPS induced the release of NO (21±0.5 uM) and TNF‐a (7185±828 pg/mL). The addition of TDL suppressed the LPS‐induced release of NO (15±0.6 uM) and TNF‐a (5016±425 pg/mL). Culture with LPS and/or TDL did not alter cell viability.Our data suggests that during stimulation with LPS, a biological factor in lymph suppressed the release of inflammatory mediators by macrophages. Furthermore, cell viability was unaltered, suggesting that that TDL augments macrophage function. Future studies will focus on the ability of lymph to suppress the inflammatory response in disease models.Support or Funding InformationThis study was funded by the National Institutes of Health R01AT004361 (LMH).
Effect of Acute Increases in Retrograde Shear on Near‐Infrared Spectroscopy Derived Microvascular Reactivity
Authors: Ramos Macarena , Black Christopher D , Branch Patrece A , Caldwell Jacob T , Wardlow Garrett C , Ade Carl J 
Published: November 2023

Periods of high vascular resistance lead to increases in retrograde shear rate, this augmented shear rate has been demonstrated to acutely decrease macrovascular endothelium‐dependent flow‐mediated dilation. However, it is unknown if similar exposures to a period of retrograde shear rate negatively impacts the microvascular response via near‐infrared spectroscopy (NIRS).PurposeDetermine the effects of acute retrograde shear rate on microvascular responses in healthy, young humans. It was hypothesized that exposure to increased levels of retrograde shear rates would elicit a decrease in post‐occlusive microvascular reactivity measured via non‐invasive NIRS.Methods17 participants (22.7 ± 2.91 yrs) completed the study. Microvascular function was measured as the post‐occlusive reactive responses for tissue saturation index (TSI%) and total hemoglobin + myoglobin ([Hb] total) in the m. rectus femoris before and after a 30‐minute retrograde shear rate treatment. The retrograde shear rate in the treatment leg (T) was achieved via a cuff placed below the knee inflated to 75 mmHg, meanwhile the contralateral leg served as control (C). Shear rate was measured in the superficial femoral artery. Due to the limitations of non‐invasive 2D Doppler ultrasound interrogating smaller vessels, the evaluation of changes in shear rate in the microcirculation could not be performed.ResultsThe cuff inflation significantly increased the retrograde shear in the treatment leg (71.2 ± 46.9 s−1 vs. 156.5 ± 63.5 s‐1, P<0.01) compared to the control leg (74.8 ± 58.6 s−1 vs. 66.6 ± 45.7 s−1, P=0.37). The peak post‐occlusive response for TSI% (T: 79.9 ±10.2 %; C: 76.8 ± 11.9%, P=0.15) and [Hb] total (T: 44.7± 29.7 μM C: 51.5 ± 43.3 μM, P=0.06) were not different between legs following the intervention. Similarly, the rate of change for StO2 (T: 6.0 ± 7.0 % s−1 104; C: 5.0 ± 6.0 % s−1 104) and [Hb] total (T: 4.0 ± 4.0 μM s−1 104; C: 3.0 ± 4.0 0 μM s−1 104) were not different between legs.ConclusionIncreases in retrograde shear rate achieved via application of cuff pressure does not alter post‐occlusive NIRS derived indices of microvascular reactivity. Results may be due to different retrograde shear patterns elicited along the arterial tree, limitations of NIRS, or limited effect of retrograde shear on microvascular function.