bluuebunny/crossref_metadata_2025 huggingface dataset:
Cyclosporine Ameliorates Reductions in Blood Pressure and Heart Rate Variability Caused by Endotoxemia in Rats: Modulation by Central PI3K/sGC/MAPKs Signaling
Authors: El‐Mas Mahmoud M , Sallam Marwa Y , Abdel‐Galil Abdel‐Galil A , El‐Gowilly Sahar M
Published: November 2023

Cyclosporine A (CSA) improves survivability in endotoxemia and offsets the associated loss in vascular reactivity and hypotension. We tested the hypothesis that CSA abrogates the reduced blood pressure (BP) and cardiac autonomic dysfunction in endotoxic rats via the modulation of phosphoinositide‐3‐kinase (PI3K)/soluble guanylate cyclase (sGC)/mitogen activated protein kinases (MAPKs) cascade in central neurons. The effects of individual pharmacologic inhibition of these molecular substrates on the interaction of CSA with hemodynamic and cardiac autonomic responses, as reflected by heart rate variability (HRV) measurement, evoked by lipopolysaccharide (LPS) were evaluated. CSA (10 mg/kg i.v.) reversed the decreases in BP and increases in HR elicited by LPS (10 mg/kg i.v.) in conscious rats. Likewise, the decreases caused by LPS in time‐domain (standard deviation of beat‐to‐beat intervals, SDRR, and the root mean square of successive beat‐to‐beat differences in R‐R intervals, rMSSD) and frequency domain (total power and low and high‐frequency spectral powers) measures of HRV were abolished by CSA. These advantageous effects of CSA disappeared in endotoxic rats treated intracisternally (i.c.) with ODQ (sGC inhibitor) in contrast to no effect for wortmannin (PI3K inhibitor). We also report divergent roles for central MAPKs in the CSA‐LPS interaction. The reversal by CSA of the hypotensive effect of LPS disappeared in rats treated concurrently with i.c SB203580 (MAPKp38 inhibitor) or PD98059 (MAPKERK inhibitor), in contrast to little effect for SP600125 (MAPKJNK inhibitor). Alternatively, the amelioration by CSA of the LPS‐evoked reductions in HRV was abolished in presence of SP600125 or PD98059, but not SB203580. Collectively, the facilitation of central circuits of sGC/MAPKs contributes to CSA counteraction of the cardiovascular actions of endotoxemia. However, the identity of the MAPK isoform involved in the CSA‐LPS interaction largely depends on the specificity of the cardiovascular response.

Support or Funding Information

Supported by the Science and Technology Development Fund, Egypt (STDF Grant No. 14895).
Central GABAA Receptors Provoke Inflammatory and Cardiovascular Consequences of Endotoxemia in Conscious Rats
Authors: El‐Mas Mahmoud M , Sallam Marwa Y , Abdel‐Galil Abdel‐Galil A , El‐Gowilly Sahar M
Published: November 2023

Gamma‐aminobutyric acid (GABA), the principal brain inhibitory neurotransmitter, plays a key role in inflammatory and neurodegenerative disease. In this study, we tested the hypothesis that central GABAergic neurotransmission mediates the detrimental inflammatory, hemodynamic, and cardiac autonomic actions of endotoxemia. The effects of drugs that block GABA receptors or interfere with GABA uptake or degradation on blood pressure (BP), heart rate (HR), and HR variability (HRV) responses elicited by i.v. lipopolysaccharide (LPS) were assessed in conscious rats. The BP lowering effect of LPS (10 mg/kg) was blunted after intracisternal (i.c.) administration of bicuculline (GABAA receptor antagonist, 3 μg/rat) or saclofen (selective GABAB receptor antagonist, 50 μg/rat). By contrast, the concomitant LPS‐evoked tachycardia and decreases in time‐ and frequency domain indices of HRV, measures of cardiac autonomic control, were abolished upon treatment with bicuculline but not saclofen. The increases in serum tumor necrosis factor‐α and interleukin‐6 caused by LPS disappeared in rats treated concurrently with bicuculline or saclofen, whereas the LPS‐evoked increases in serum nitric oxide metabolites was reversed by bicuculline only. We also report that none of the effects of endotoxemia was altered in rats treated with i.c. tiagabine (GABA reuptake inhibitor, 100 μg/rat) or vigabatrin (GABA transaminase inhibitor, 200 μg//rat). These data suggest a major role for central GABAA receptors in the inflammatory and cardiovascular effects of endotoxemia.

Support or Funding Information

Supported by the Science and Technology Development Fund, Egypt (STDF Grant No. 14895).
Histamine serves as an aggravating factor in major end‐organ injury associated with sepsis
Authors: Hattori Mizuki , Ohashi Wakana , Yamazaki Mitsuaki , Hattori Yuichi
Published: November 2023

Plasma histamine levels are elevated in animal models of sepsis as well as in patients with septic shock. We examined whether histamine contributes to organ/tissue damage in mice with cecal ligation and puncture (CLP)‐induced sepsis. We found that plasma and tissue histamine levels were elevated and tissue gene expression levels of histidine decarboxylase (HDC) were increased in mice after CLP. Furthermore, H1 receptor gene expression was up‐regulated in the heart, spleen, and intestine, and H2 receptor gene expression was up‐regulated in the liver and kidney. Treatment with combination of H1 and H2 receptor antagonists significantly declined increases in serum aminotransferase activity, creatinine levels, and pro‐inflammatory cytokines in CLP mice. Histopathological examinations showed that the blockade of H1 and H2 receptors significantly reduced acute lung and kidney injury after CLP. HDC knockout mice behaved similar to mice treated with both H1 and H2 receptor antagonists in terms of reductions in hematological and morphological changes when the animals were rendered septic by CLP. These results suggest an aggravating role of histamine in the development of major end‐organ dysfunction and failure associated with sepsis.
Doxorubicin Acutely Inhibits Lymph Flow in Rat Mesenteric Lymph Vessels
Authors: Stolarz Amanda J , Fletcher Terry W , Marecki John C , Sarimollaoglu Mustafa , Galanzha Ekaterina , Zharov Vladimir , Klimberg Suzanne , Rusch Nancy J
Published: November 2023

Arm lymphedema is a major complication after surgery and/or radiation for breast cancer. This life‐long and disfiguring complication can cause serious medical problems including lymphangitis, cellulitis, and other recurrent infections. Doxorubicin (DOX) is often a central component in chemotherapy to prevent metastases or recurrence of breast cancer, but this cytotoxic drug increases the incidence and severity of lymphedema as an off‐target effect. Interestingly, the mechanisms by which DOX contributes to arm lymphedema have not been elucidated. We hypothesized that DOX directly suppresses lymphatic drainage by disrupting lymph vessel (LV) contractile function. Rats were anesthetized and one loop of mesentery was exposed on a heated microscope stage. High‐resolution optical imaging of rat mesenteric LVs in vivo revealed that continuous superfusion of DOX (0.05 to 10 μmol/L) progressively reduced positive volumetric lymph flow to ~30% of baseline (t=20 min, n=6) with an IC50 of 0.66 μmol/L. This effect of DOX was partially reversed by drug washout. Data were corrected for solvent and time controls (n=5–6). In a subsequent study, baseline measurements were recorded for 10 min, and then rats were injected via tail vein with a clinically relevant dose of DOX (10 mg/kg) or equivalent volume of saline. Mesenteric lymph flow was measured continuously for 2 hr post‐injection. At 0.75–1.25 hr post‐ injection, DOX significantly reduced positive volumetric flow to ~45% of baseline, whereas saline injection increased positive volumetric flow by ~35% from baseline (n=4–5). HPLC was used to determine corresponding DOX plasma levels during the measurement period. The average plasma concentration of DOX was 0.15±0.06 μmol/L (86 ± 34 ng/mL) and 0.10±0.02 μmol/L (59±13 ng/mL) at 1 and 2 hr after injection, respectively (n=5). These values were similar to DOX concentrations used in the superfusate studies and equivalent to plasma DOX concentrations achieved during chemotherapy in patients. Thus, clinically relevant concentrations of DOX appear to directly and acutely inhibit LV contractile function in vivo, and the resulting compromise of lymph flow represents a possible contributing mechanism of drug‐induced lymphedema.

Support or Funding Information

Funded by Rho Chi‐AFPE Graduate Fellowship, UAMS Pilot Grant, and NIH/NCI R21CA131164 Grant.
The Effect of the CXCR1/2 Antagonist SCH257123 in a Mouse Model of Severe Asthma
Authors: Young Alan , Nath Puneeta , Sadler Emma , Thang Kevin , Russell Vince
Published: November 2023

Objective

Severe asthma patient phenotypes are characterised as hard to control by low dose inhaled corticosteroids (ICS) and patients often require high doses of oral steroids for optimum symptom control. There is a high unmet medical need for novel therapies for the treatment of this disease. Neutrophilic airway inflammation has also been associated with corticosteroid insensitivity in the severe asthmatic population. In the current study, we have investigated the effect of a CXCR1/2 antagonist, SCH257123 (SCH), in a mouse severe asthma model known to be steroid insensitive.

Methods

BALB/c mice were sensitised subcutaneously (s.c.) with house dust mite (HDM) emulsified in Complete Freunds adjuvant (CFA) and 14 days later animals were administered HDM via the intranasal (i.n.) route. Animals were dosed with SCH (10 or 30 mg/kg, p.o., 1hr pre‐ and 5 hrs post‐HDM challenge), Dexamethasone (DEX) 1 mg/kg, p.o., 1hr pre‐HDM challenge), or the appropriate vehicle. The mice were killed 24hrs post‐HDM challenge, and a bronchoalveolar lavage (BAL) was performed to determine total and differential cell numbers. Additionally, levels of IFNγ, IL‐1β, IL‐2, IL‐4, IL‐5, IL‐6, IL‐10, IL‐12p70, KC/GRO and TNFα were measured in the BAL fluid.

Results

HDM‐challenge caused a significant increase in pulmonary inflammation, comprised of a mixed cell population of neutrophils and eosinophils. Pre‐treatment with 10 and 30mg/kg SCH only inhibited neutrophil cell numbers by a maximum of 30% in the BAL which was not significantly different when compared to the HDM‐vehicle treated group. As is consistent in this model, DEX did not significantly inhibit either the eosinophilic or neutrophilic inflammation. HDM‐challenge increased IFNγ, IL‐10 and TNFα levels in the BALF (p<0.0001) which were decreased by DEX (p<0.01) but not SCH. The levels of IL‐1β, IL‐4, IL‐6, and IL‐12p70 were also increased by HDM‐challenge, but were unaffected by both SCH and DEX. Of interest, BAL fluid levels of IL‐2, IL‐5 and KC/GRO were increased following HDM challenge, unaffected by DEX, but further increased by SCH (all p<0.001).

In summary, the CFA/HDM severe asthma model has a cellular infiltration insensitive to both steroids and a CXCR1/2 antagonist, at doses known to work in mouse models of neutrophilic inflammation (Chapman et al, JPET 2007 322(2):486–93). Of interest was the increase in the levels of several mediators associated with neutrophil recruitment in the HDM‐challenged mice following SCH administration, which may have limited its efficacy. In the clinic, SCH has been shown to reduce neutrophil numbers in the sputum of severe asthmatics by approximately 36%, which is of similar magnitude to that seen in this model (Nair et al Clin Exp Allergy, 2012 42(7):1097–103).

Support or Funding Information

Funded by Charles River
Anti‐TNF‐alpha Antibodies : Pharmacological Properties and Clinical Aspect in Autoimmune Diseases
Authors: Cetrone Michela , Tricarico Domenico
Published: November 2023

Therapeutic IgG1 mAbs have high efficacy in treating TNFα‐related immunological diseases, however differing in their pharmacological and clinical responses. Several mAbs are currently available: Infliximab, Etanercept, Adalimumab, Certolizumab, Golimumab, and the biosimilars of Infliximab. These mAbs show a neutralizing action against TNF‐α, which is mediated by the FAB fragment, and complement‐dependent cytotoxicity (CDC) and antibody‐mediated cellular cytotoxicity (ADCC) which are mediated by the Fc fragment. However, the current therapy in these disorders does not fulfill the clinical requests in some patients and the factors affecting the lack of response are not fully understood. Possible explanations for therapeutic failure include insufficient compliance/bioavailability, pharmacokinetics (PK) and pharmacodynamic (PD) issues and the induction of anti‐drug‐antibodies (ADA). Two main strategies available in case of non response are: (1) increasing drug exposure by shortening the dosing interval or increasing the dose and (2) switching to another drug. More recently, the use of therapeutic strategies based on the measurements of the anti‐TNF drug levels and ADA, rather than dose‐escalation has proven to be cost‐effective, as this allows individualized patient‐tailored strategies. In the present review we have analyzed the state of the art and possible perspectives in the TNF‐α related autoimmune diseases taking into account the pharmaco‐economic impact of the novel strategy and of the biosimilar drugs.
Preclinical Evaluation of Flt3 Ligand to Improve T Cell Adaptive Immune Response During Sepsis
Authors: Patil Naeem K , Bohannon Julia K , Luan Liming , Guo Yin , Sherwood Edward R
Published: November 2023

Background

Sepsis is a leading cause of death in the United States. Severely burned patients are highly susceptible to opportunistic infections and sepsis, leading to multi‐organ failure and death. Studies by Hotchkiss and colleagues show that T cell dysfunction significantly contributes to impaired immune response during sepsis in non‐burn subjects. However, the changes in T cell adaptive immunity after burn wound sepsis have not been investigated in detail. We used a clinically relevant mouse model of burn wound infection to assess adaptive immune system function. Furthermore, we evaluated the cytokine, Fms‐like tyrosine kinase‐3 ligand (Flt3L), to improve T cell adaptive immunity post burn wound sepsis. Flt3L is known to stimulate the expansion of hemopoietic progenitors, particularly dendritic cells.

Methods

8–10 weeks old male BALB/c mice were subjected to 35% total body surface area full thickness burn and the wound was infected with Pseudomonas aeruginosa on day 4 post‐burn. Flow cytometry was used to characterize the cell counts and phenotype of CD4+ and CD8+ T and dendritic cells in spleen and wound draining lymph nodes. Flt3L (10 μg, i.p.) was administered daily for 4 days following burn injury.

Results

Wound infection led to severe sepsis in the mice as evidenced by detection of bacteria in blood and lungs, and multi‐organ injury (increased markers of liver and kidney injury) on day 2 after infection and mortality rate of approximately 80% by seven days. We observed a significant decline (>80%) in blood absolute lymphocyte count and CD4+ and CD8+ T cell counts in the spleen and burn‐draining lymph nodes of wound infected mice as compared to non‐infected burn mice on day 2 post infection. Flt3L significantly attenuated the infection induced decline in CD4+ and CD8+ T cell counts in the spleen. Wound infection also caused a decline in the CD11c+ dendritic cell numbers in lymph nodes. Flt3L stimulated the expansion of both the splenic and lymph node dendritic cells and protected against the dendritic cell loss in the lymph nodes. Furthermore, wound infection caused an increase in the expression of Programmed Death‐Ligand 1 (PD‐L1) expression on dendritic cells, F4/80+ macrophages and Ly6C+ inflammatory monocytes in the spleen. PD‐L1 is known to interact with its binding partner PD‐1 on T cell surface leading to T cell inhibition. Flt3L attenuated the increase in PD‐L1 expression and thus indirectly improves T cell function.

Conclusion

Burn wound sepsis causes significant adaptive immune system dysfunction and Flt3L represents a novel therapeutic cytokine to protect T cell function during sepsis and merits further investigation.

Support or Funding Information

Supported by NIH R01 GM66885
DNA‐Dependent Protein Kinase Inhibition Prevents Manifestation of Acute Lung Injury in Mice, a Novel Target Associated with Th1 Type Disease
Authors: Pyakurel Kusma , Ghonim Mohamed , Ibba Salome , Tarhuni Abdelmetalab , Wang Jeffery , Boulares Hamid
Published: November 2023

Background

The acute respiratory distress syndrome (ARDS), a clinical complication of severe acute lung injury (ALI) in humans, is a leading cause of morbidity and mortality in critically ill patients. ALI is characterized by disruption of the lung alveolar‐capillary membrane barrier and resultant pulmonary edema associated with a proteinaceous alveolar exudates which is explained by injury to both the vascular endothelium and alveolar epithelium. We previously reported that DNA‐dependent Protein Kinase (DNA‐PK) inhibition prevents in‐vitro differentiation of T‐helper 1(Th1) cells and Th1 specific cytokine production under Th1 skewing condition.

Materials and methods

LPS‐induced ALI, Th1 type, murine disease model was used. Wild‐type or DNA‐PK heterzygous animals were anesthetized using i.p administration of xylazine/ketamine after which 10mg/kg LPS was intratracheally administered. Some group of mice received 5mg/kg of DNA‐PK inhibitor, NU 7441, 30 min after LPS administration. Cytospin and subsequent diff‐quick staining, myeloperoxidase assay, cytokine analysis and recording of dry and wet lung weights were performed.

Results

Administration of DNA‐PK inhibitor, NU 7441, reduced production of inflammatory cytokines in the broncheoalveolar lavage fluid (BALF). Such effects correlated with a marked reduction in inflammatory cells such macrophages, neutrophils and lymphocytes in the lungs. Reduction in myeloperoxidase expression in lung homogenates in NU 7441 treated groups further confirmed the inhibition of neutrophils recruitment in the lungs. Furthermore, administration of NU 7441 reduced pulmonary edema in the mice, as measured by lung water retention volume (wet to dry weight ratio). DNA‐PK heterozygosity also prevented manifestation of ALI symptoms similar to those observed in NU 7441 treated animals.

Conclusion

DNA‐PK plays a critical role in ALI and, therefore, may constitute a novel therapeutic target for the treatment of the disease.

Support or Funding Information

Support: NIH; AHA; LCRC funds
Telomere‐independent Rap1 Induces Cytokine Production In Pro‐inflammatory Macrophages Through NFκB Signaling
Authors: CAI Yin , VANHOUTTE Paul M. , TANG Eva H.C.
Published: November 2023

Repressor activator protein 1 (Rap1), an established telomere‐associated protein, is essential for maintaining telomere length and structural integrity, but it also exerts other non‐telomeric functions. The present study tested the hypothesis that Rap1 is released into the cytoplasm and induces production of pro‐inflammatory cytokines via nuclear factor kappa B (NFκB) signaling in macrophages, a cell type involved in the development and progression of atherosclerotic lesions. Western blotting analysis confirmed that Rap1 was present in the cytoplasm of differentiated human monocytic leukemia cells (THP‐1, a macrophage‐like cell line). Co‐immunoprecipitation assay revealed a direct interaction between Rap1 and I kappa B kinase (IKK). Knockdown of Rap1 significantly suppressed lipopolysaccharide‐mediated activation of NFκB (by 39.0%), and phosphorylation of inhibitor of kappa B α (IκBα) and p65 in THP‐1 macrophages (by 52.7% and 32.0%, respectively). The reduction of NFκB activity was paralleled by a decreased production of NFκB‐dependent pro‐inflammatory cytokines [including interleukin (IL)‐8, IL‐1β and monocyte chemotactic protein‐1] and an increased expression of IκBα (native NFκB inhibitor) in various macrophage models with pro‐inflammatory phenotype, including THP‐1, mouse peritoneal macrophages and bone marrow‐derived M1 macrophages. These changes were observed selectively in pro‐inflammatory macrophages but not in bone marrow‐derived M2 macrophages (with an anti‐inflammatory phenotype). Furthermore, in human atheroma, endothelial and smooth muscle cells elaborate cytokines and contribute to the overall inflammatory environment. However, knockdown or knockout of Rap1 does not influence the expression of NFκB‐dependent targets in human umbilical vein endothelial cells, human aortic smooth muscle cells or mouse lung endothelial cells. Immunostaining revealed that Rap1 was localized mainly in macrophage‐rich areas rather than in endothelial or smooth muscle cell‐rich areas in human atherosclerotic plaques and that the presence of Rap1 was positively correlated with the advancement of the disease process. In conclusion, in pro‐inflammatory macrophages, Rap1 promotes cytokine production via NFκB activation favoring a pro‐inflammatory environment which may contribute to the development and progression of atherosclerosis.

Support or Funding Information

This study was supported by National Natural Science Foundation of China (NSFC 81270383).
Norepinephrine Protects Cerebral Autoregulation and Reduces Hippocampal Necrosis after Traumatic Brain Injury via Block of ERK MAPK and IL‐6 in Juvenile Pigs
Authors: Armstead William , Riley John , Vavilala Monica
Published: November 2023

Traumatic brain injury (TBI) contributes to morbidity in children, and boys are disproportionately represented. Cerebral autoregulation is impaired after TBI, contributing to poor outcome. Cerebral Perfusion Pressure (CPP) is often normalized by use of vasoactive agents to increase mean arterial pressure (MAP). In prior studies of 1–5 day old newborn piglets, we observed that norepinephrine (NE) preferentially protected cerebral autoregulation and prevented hippocampal necrosis in females but not males after fluid percussion injury (FPI). The ERK isoform of mitogen activated protein kinase (MAPK) produces hemodynamic impairment after FPI, but less is known about the role of the cytokine IL‐6. We investigated whether NE protects autoregulation and limits histopathology after FPI in older juvenile (4 week old) pigs and the role of ERK and IL‐6 in that outcome by sex. Results show that NE significantly protects autoregulation and prevents reduction in CBF in both male and female juvenile pigs after FPI; co‐administration of the ERK antagonist U 0126 with NE fully protects both indices of outcome. Papaverine induced dilation was unchanged by FPI and NE. NE blunted ERK MAPK and IL‐6 upregulation in both males and females after FPI. NE attenuated loss of neurons in CA1 and CA3 hippocampus of males and females after FPI. These data indicate that NE protects autoregulation and limits hippocampal neuronal cell necrosis via block of ERK and IL‐6 after FPI in both male and female juvenile pigs. These data suggest that use of NE to improve outcome after TBI is both sex and age dependent.

Support or Funding Information

NIH R01 NS090998
The Effect of Left Ventricular‐Central Artery Coupling on Cerebrovascular Hemodynamics: Insights from Lower Body Negative Pressure
Authors: Tomoto Tsubasa , Imai Tomoko , Ogoh Shigehiko , Maeda Seiji , Sugawara Jun
Published: November 2023

Substantial pulsatile fluctuation of cerebral blood flow is an adverse impact on vulnerable brain tissue. Since endurance‐trained athlete exhibits left ventricular eccentric remodeling, the transient increase in venous return may result in substantial increase in stroke volume (SV), which cause of increase in pulsatile flow fluctuation. The aim of this study was to test the hypothesis that, in endurance‐trained, substantial increase in SV does not cause augmented pulsatile fluctuation of cerebral blood flow because of high aortic buffering function. Endurance‐trained (ET, n=10) and age‐matched sedentary (SED, n=10) young healthy men underwent lower body negative pressure (LBNP) (−30 mmHg for 4 minutes) stimulation and release that initiated an acute increase in venous return and consequently increased in SV. The hemodynamic response was evaluated following release of LBNP up to 15 seconds. SV (via Modeflow method) and pulsatility index of middle cerebral arterial blood flow velocity (PIMCAV, via transcranial Doppler) significantly increased after release of LBNP in both groups. The increase in SV was significantly greater in ET than in SED (P<0.01), whereas there was no group‐difference in responses of PIMCAV. SV/PP, an index of aortic buffering function, was significantly higher at rest in ET compared with SED. Furthermore, after the LBNP release SV/PP significantly elevated in ET but not in SED. These results suggest that acute postural change from standing to supine position greatly increases SV in ET; however, substantial augmentation of cerebral pulsatile fluctuation does not occur. This phenomenon might be associated with superior aortic buffering function in ET.
Cerebrovascular vasoconstrictor responses in young and older adults: effect of age and exercise
Authors: Miller Kathleen B , Harvey Ronee E , Joyner Michael J , Barnes Jill N
Published: November 2023

Recent research focuses on the cerebrovascular response to vasodilatory stimuli as an index of cerebrovascular health; however, vasoconstrictor responses in the brain are likely equally important. We previously have shown that cerebral vasoconstrictor responses to hypocapnia are not affected by aging; however, this was evaluated in primarily sedentary adults. Therefore, we hypothesized that middle cerebral artery velocity (MCAv) vasoconstrictor responses to hypocapnia are dependent on age and habitual physical activity. We evaluated 13 young physically active (YA; age = 30±5 y; VO2max = 45±8 mL/kg/min), 6 young sedentary (YS; age = 29±4 y; VO2max = 26±3 mL/kg/min), 10 older physically active (OA; age= 61±6 y; VO2max =35±7 mL/kg/min) and 8 older sedentary (OS; age = 65±8 y; VO2max 23±2 mL/kg/min) adults during the recovery from inhaled 6% CO2 to room air. Mean arterial pressure (MAP) end tidal CO2 (ETCO2) and MCAv were recorded throughout. Using a breath‐by breath analysis, cerebrovascular conductance index (CVCi=MCAv/MAP) reactivity was calculated as a slope of CVCi and ETCO2 and used to quantify vasoconstrictor responses. CVCi reactivity was higher in YA adults (slope=2.74±0.9 AU) compared with both YS (slope=2.20±1.1 AU) and older groups (OA: slope=2.08±0.5 AU; OS: slope=2.07±0.7 AU; p<0.05 for all). There were no significant differences in CVCi reactivity between YS and either OA or OS (p=0.94, p=0.99 respectively). Additionally, CVCi negatively correlated with age (r=−0.38, p<0.05). Our results indicate that aging attenuates the cerebral vasoconstrictor response to hypocapnia in older adults in comparison to physically‐active young adults, but not compared to sedentary young controls. A sedentary lifestyle resulted in attenuated vasoconstrictor responses in the young sedentary group, as their responses were not different than the older adults. It remains unclear how habitual physical activity preserves the cerebral vasoconstrictor response to hypocapnia in young people, and if a structured exercise training intervention would impact this response in older adults.

Support or Funding Information

NIH HL118154
Implications of Electrical Communication in Brain Blood Flow Regulation and Stroke Injury
Authors: Zechariah Anil , Tuor Ursula I , Welsh Donald G.
Published: November 2023

An integrated network of cerebral arteries actively coordinates brain blood flow in accordance with metabolic demands. Large regional changes require synchronised vasomotor responses across vessel segments starting at the origin of a stimulus and spreading to the major upstream resistors. The coordination of vasomotor tone is intimately tied to the spread of charge through gap junctions, a process that equalizes membrane potential, [Ca2+] and myosin light chain phosphorylation among thousands of smooth muscle cells. Coordinated responses are critically important during cerebrovascular accidents (i.e. stroke) where the synchronized dilation of collateral vessels diverts flow into ischemic tissue. We hypothesized that electrical communication, via gap junctions, plays a central role and that dysfunctional communication between vascular cells impairs collateral responses, increasing stroke injury. Using isolated cerebral arteries from mouse, hamster and resected human tissue, we show that electrical stimuli can effectively spread along vascular cells in an endothelium dependant manner. Genetic deletion of Connexin40 (Cx40−/−), a component protein of gap junctions, compromised electrical communication in the cerebral arteries. Subjecting Cx40−/− mice to focal cerebral ischemia induced greater deficit in cerebral blood flow than in wild type controls, during stroke and the subsequent reperfusion period. This attenuation of blood flow translated to augmented stroke injury in the Cx40−/− mice. In closing, our study illustrates the presence of robust electrical communication and that compromising this integrated process restricts the ability of the cerebral circulation to respond to, and moderate injury from vascular accidents, including stroke.

Support or Funding Information

This work is supported by an operating grant to Dr Welsh from the Natural Science and Engineering Council of Canada (NSERC). Dr Welsh is the Roraback Chair in Neuroscience and Vascular Biology at the University of Western Ontario. A. Zechariah is supported by Canadian Institutes of Health Research (CIHR) Postdoctoral scholarship, Alberta Innovates Postdoctoral scholarship and Eyes High Postdoctoral fellowship. Dr. Tuor is supported by a grant from CIHR.
Differential wall shear stress patterns in cerebral circulation of prediabetic adults: Possible evidence for increased stroke risk?
Authors: Aleckson Benjamin P , Kellawan Mikhail , Harrell John W. , Schrauben Eric M. , Hoffman Carson A. , Roldan‐Alzate Alejandro , Wieben Oliver , Schrage William G.
Published: November 2023

Proper endothelial function is crucial to cerebral vascular health and is affected by wall shear stress (WSS) patterns. Metabolic syndrome (MetSyn) is a prediabetic state that contributes to endothelial dysfunction which can lead to clinical conditions, such as, stroke. The aim of this study was to quantify and compare resting WSS in multiple conduit cerebral arteries in healthy and MetSyn subjects. We hypothesized adults with Metsyn will display reduced WSS in cerebral arteries when compared to healthy controls. 7 healthy controls (29±2y) and 7 MetSyn (37±3y) underwent a single four‐dimensional (4D) flow MRI scan during quiet rest in the supine position. Data acquisition was based on a radial undersampling scheme named Phase Contrast Vastly‐undersampled Isotropic Projection Reconstruction (PC VIPR) used to generate a phase contrast (PC) angiogram, as well as, measure cerebral blood flow (CBF), and WSS non‐invasively without use of a contrast agent (three directional velocity encoding at a spatial and temporal resolution of 0.68 mm and 20 cardiac phases, respectively). Average scan time was ~ 5 minutes and produced large imaging volumes. Nine arteries were analyzed: Middle cerebral (MCA) ×2, anterior cerebral (ACA) ×2, internal carotid (ICA) ×2, vertebral (VA) ×2, and basilar. WSS was measured by segmenting the vascular tree from the PC angiograms and subsequently calculating the velocity gradient at the vessel wall from the 4D Flow MRI data over ~ 3 voxels. Total CBF was calculated as the sum of the left and right ICA and basilar artery. Resting total CBF was 577±45 ml· min−1 in healthy controls and 499±46 ml ·min−1 in MetSyn (p=0.25). Metsyn exhibited lower WSS (Pa) in the left MCA (3.7±0.2 vs. 3.0±0.2; p=0.01), right ACA (3.4±0.2 vs. 2.9±0.2; p=0.05), right ICA (2.7±0.3 vs. 1.8±0.1; p=0.01) and left ICA (2.8±0.3 vs. 1.5±0.1; p<0.01). This non‐invasive MRI approach provides new insight into local flow and shear patterns that might have a large impact on cerebral endothelial function. Younger adults with MetSyn exhibit lower WSS in anterior portions of the brain. Furthermore, these findings are consistent with the observation that stroke occurs most commonly in the anterior cerebral circulation. Given the young age (< 45 y) of these subjects, we propose chronically reduced WSS leads to endothelial dysfunction in middle/old age, thereby contributing to increased risk and severity of stroke in MetSyn.

Support or Funding Information

Funded by the American Diabetes Association and an American Physiological Society Undergraduate Research Summer Fellowship.
Heparin's Anti‐Inflammatory Effects in Vascular Endothelial Cells are Mediated Through Transmembrane Receptor 184A
Authors: Farwell Sara Lynn Nicole , Lowe‐Krentz Linda
Published: November 2023

The glycosaminoglycan heparin has been used as an anti‐coagulant in the treatment of cardiovascular diseases for decades. The mechanism of heparin binding to enzyme inhibitor antithrombin III in the coagulation cascade has been well‐documented. Heparin has also been shown to illicit anti‐proliferative and anti‐inflammatory responses in vascular cells, though mechanism(s) remain unclear. Recently we have used antibodies that mimic heparin effects in vascular smooth muscle cells to identify transmembrane protein 184A (TMEM184A) as a putative heparin receptor. The objective of this study was to investigate TMEM184A expression and function in vascular endothelial cells. We observed TMEM184A expression in cultured endothelial cells and in the zebrafish caudal fin vasculature through immunofluorescence using commercial antibodies against a region near the N‐terminus and a region of 20 amino acids of an internal region. To determine whether heparin effects on inflammatory responses were mediated through TMEM184A, rat aortic endothelial cells (RAOECs) were electroporated with control or TMEM184A shRNA. Control and knockdown RAOECs were treated with 200 μg/ml heparin for 20 min, followed by 25 ng/mL TNFα. Quantitative immunofluorescence of activated JNK or p38 showed that heparin treatment prior to TNFα significantly decreased JNK and p38 activation in control shRNA cells compared to cells treated with TNFα alone. However, in TMEM184A knockdown cells, heparin pre‐treatment did not decrease JNK or p38 activation. Heparin induction of DUSP1 was found to be critical for these effects. In control ECs, heparin pre‐treatment decreased TNFα‐induced stress fiber formation. To investigate whether TMEM184A was also necessary for these effects, stress fibers were quantified through immunofluorescence. In TMEM184A knockdown RAOECs, heparin pre‐treatment did not decrease TNFα‐induced actin stress fiber formation. In conclusion, our results show that TMEM184A is expressed specifically in the vasculature in vitro and in vivo. We provide functional evidence that anti‐inflammatory effects of heparin are dependent at least in part on TMEM184A. Further investigation of heparin's anti‐inflammatory effects through TMEM184A in the vasculature is crucial for developing and improving therapeutic strategies in vascular disease.

Support or Funding Information

This work was supported by NIH grant HL54269 to LLK
Microgravity‐Induced Activation of Nlrp3 Inflammasomes in Mouse Vascular Endothelial Cells
Authors: Xia Min , Nguyen Thaison P , Bao Jun‐Xiang , Meng Nan , Boini Krishna M , Li Pin‐Lan
Published: November 2023

In the microgravity environment, astronauts usually have cardiovascular deconditioning, even endothelial dysfunction that may initiate or accelerate coronary heart disease. Although pro‐inflammatory cytokines were reported to increase in microgravity, which may lead to inflammation, the underlying molecular mechanism instigating this microgravity‐induced inflammation remains poorly understood. In the present study, we tested whether microgravity activates Nlrp3 inflammasomes in endothelial cells (ECs) and thereby turns on vascular inflammation. By confocal microscopy and 3D culture of mouse ECs in rotating wall vessel bioreactor to generate microgravity (MG), we detected the enhancement of co‐localization of Nlrp3 with apoptosis‐associated speck‐like protein (ASC) or with caspase‐1 when ECs were exposed to MG. Biochemical analyses revealed that MG significantly increased the cleavage of procaspase‐1 into active caspase‐1 and enhanced caspase‐1 activity (1.3 folds) and IL‐1β production (2.6 folds) in ECs compared to those cells under normal gravity (NG). The formation of active caspase‐1 was inhibited by a potassium ion (K+) channel blocker, glibenclamide, but not affected by antioxidant N‐acetyl‐L‐cysteine (NAC) or cathepsin B inhibitor, CA‐074 methyl ester. In addition, we found that more ceramide‐enriched macrodomains or platforms on the plasma membrane were observed in ECs under MG compared to cells under NG. These results suggest that MG leads to activation of Nlrp3 inflammasomes in ECs through a K+ efflux and ceramide‐enriched membrane platform formation. This activation of Nlrp3 inflammasomes may represent a novel initiating mechanism to produce the inflammatory response and endothelial dysfunction during MG.

Support or Funding Information

Supported by NIH grants HL057244, HL075316, HL091464 and HL122937
Organ Targeted Copper Delivery Reverses Fibrosis in Rhesus Monkey Model of Myocardial Ischemic Infarction
Authors: Xiao Ying , Nie Xin , Han Pengfei , Kang Y. James
Published: November 2023

Excessive collagen deposition post myocardial ischemic injury hastens heart failure. Copper supplementation significantly improved cardiac function and reduced fibrosis in myocardial ischemic infarction. The present study was undertaken to understand the link between the reduced fibrosis and the recovery of cardiac function. Male Rhesus monkeys of 4–5 years old were subjected to coronary artery ligation to induce myocardial infarction. At the end of fourth weeks after the surgery, ultrasound contrast microbubble composed of Cu‐albumin coating for cardiac organ‐specific Cu delivery through ultrasound manipulation was used to treat the monkeys twice a week for other four weeks. Collagen deposition in the infarct hearts was observed 4 weeks and further enhanced 8 weeks after ischemia. The collagen content in the infarct myocardium was not changed significantly after Cu treatment. However, type I and III collagen mRNA levels were decreased, and collagen network became loosened, along with an increase in the capillary density. Lysyl oxidase (LOX), an enzyme related to collagen deposition, was increased, and metalloproteinase‐1 (MMP‐1), an enzyme involved in collagen degradation, was decreased in the infarct area relative to sham operated control and remote area. After Cu treatment, MMP‐1 was significantly increased, and the ratio between MMP‐1/LOX was dramatically elevated. These results thus suggest Cu‐induced MMP‐1 elevation in the infarct area is mostly likely responsible for the breakage of collagen cross‐linking leading to diminished collagen deposition and improved angiogenesis and recovery of cardiac function.

Support or Funding Information

This study is supported by National Science Foundation of China (81230004 and 81300109).
Absence of TRPV4 protects heart from pressure‐overload induced injury via inhibition of Rho/MRTF‐A mediated cardiac fibrosis
Authors: adapala Ravi Kumar , Cappelli Holly C , Ohanyan Vahagn A , Luli Jordan , Thoppil Roslin J , Paruchuri Sailaja , Meszaros J Gary , Chilian William M , Thodeti Charles K
Published: November 2023

The cardiac remodeling following cardiac injury, such as a myocardial infarction or heart attack, involves the differentiation of cardiac fibroblasts (CFs) into highly contractile and hyper‐secretory myofibroblasts. However, over deposition of extracellular matrix (ECM) can often times lead to cardiac fibrosis. Although both soluble and mechanical factors mediate CF differentiation, the mechanotransduction mechanisms are poorly understood. Recently, our lab has shown that the mechanosensitive ion channel Transient Receptor Potential Vanilloid 4 (TRPV4) plays an indispensable role in regulating CF differentiation by integrating soluble and mechanical factors in vitro. Here, we investigated the physiological significance and molecular mechanism(s) by which TRPV4 regulates cardiac remodeling in vivo. Using trans‐aortic constriction (TAC) to induce pressure‐overload injury, we found that TRPV4 knockout (TRPV4KO) mice demonstrated preserved ejection fraction and decreased left ventricular mass 28 days post‐injury, when compared to their wild‐type (WT) counterparts. Immunohistological analysis revealed that absence of TRPV4 resulted in decreased cardiomyocyte hypertrophy, fibrosis, and CF differentiation as evidenced by wheat germ agglutinin, picrosirius red, and alpha‐SMA staining, respectively. To delineate the molecular mechanisms, we stimulated CFs isolated from WT and TRPV4KO mice with TGF‐b1 and found that CF differentiation was significantly attenuated in TRPV4KO mCF. Further, pre‐treatment with TRPV4 antagonist, AB159908, significantly inhibited TGF‐b1‐induced activation of RhoA in WT mCFs, suggesting that Rho is downstream of TRPV4 in CF differentiation. Further, we found a mechanosensitive transcription factor, MRTF‐A (myocardin‐related transcription factor‐A), which is downstream of Rho, was activated by TGF‐b1 or TRPV4 agonist, GSK1016790A. Finally, inhibition of MRTF‐A attenuated TGF‐β1‐induced CF differentiation. Altogether, these findings indicate that TRPV4 channels mediate cardiac fibrosis through Rho/MRTF‐A pathway, and TRPV4 could be a novel therapeutic target for the treatment of pressure‐overload‐induced cardiac hypertrophy and heart failure.
Left Ventricular Hypertrophy Is Associated With Decreased α But Not β‐Myosin Gene Expression in Spontaneously Hypertensive Nonhuman Primates
Authors: Weaver Chelsea Christina , Gutierrez Anthony , Osborn Jeffrey L
Published: November 2023

Essential hypertension (EH) is associated with increased risk of cardiovascular disease and heart failure. Left ventricular hypertrophy (LVH) also increases the risk of heart failure yet the mechanisms underlying ventricular cardiac remodeling remain unclear. The vervet monkey (Chlorocebus aethiops sabaeus) is a highly translational model of hypertension as they share more than 97% of their genome with humans and naturally develop spontaneous hypertension. We have identified vervets from outbred colonies as either hypertensive (HT, systolic blood pressure, SBP≥140 mmHg) or normotensive (NT, SBP<120 mmHg) using forearm plethysmography under ketamine sedation (15 mg/kg i.m.). We hypothesize that in the vervet, spontaneous hypertension is associated with LVH combined with altered gene expression of myocardial contractile proteins and pro‐inflammatory agents similar to other dietary, surgical pathology or pharmacological induced models of hypertension in quadripedal mammals. Cardiomyocyte cross‐sectional area of left but not right ventricles was greater in HT than NT individuals (HT 1658μm2±515, n=6 vs. NT 791μm2±210, n=7; p<0.01) demonstrating significant morphological LVH in this model of spontaneous hypertension. Semi‐quantitative RT‐PCR assessed left ventricular α/β myosin gene expression of HT (mean SBP=171.5±7.3 mmHg; n=15) and NT (mean SBP 98.9±2.4 mmHg; n=14) vervets. Gene expression in left ventricular myocardium was normalized using reference gene RPS13A. α‐myosin was downregulated in HT versus NT vervets (HT RQ=0.10±0.03 vs. NT RQ=0.22±0.04; p<0.05), whereas β‐myosin expression was not different (HT RQ=0.22±0.17 vs. NT RQ=0.20±0.16; p=0.83). The LVH pro‐inflammatory intracellular adhesion molecule 1 (ICAM‐1) gene expression also was measured using RNA extracted from left ventricular myocardium. ICAM‐1 gene expression in HT and NT vervets was not different (HT RQ=0.11±0.03 vs. NT 0.15±0.07; p=0.47). We conclude that downregulation of α‐myosin in the left ventricular myocardium in HT vervets may represent the early onset stages of the shift of α to β myosin characteristic of long‐term LVH and established heart failure after chronic elevation of systemic vascular resistance and blood pressure. At present, pro‐inflammatory ICAM‐1 is not associated with development of LVH in HT vervets. Future studies will further divide nonhuman primate groups into HT with LVH, HT without LVH, and NT to more selectively evaluate molecular protein expression with myocardial hypertrophy in spontaneous hypertension as well as the expression of additional inflammatory cytokines within the myocardium.

Support or Funding Information

Supported by Biomedical Sciences Research Group, L.L.C.
Evaluation of biological and mechanical variations in hypertensive animal models
Authors: Lue Sheng‐I , Zhuang Jun‐Cheng , Fu Yaw‐Syan , Lu Tzongshi
Published: November 2023

Introduction and Hypothesis

Hypertension (HT) is a multifactorial cardiovascular disorder involves in variety genetic and environmental factors. To properly study the pathophysiology of hypertension, robust and reproducible experimental animal models are required. The ideal HT animal model should have human‐like cardiovascular anatomy, hemodynamics, and physiology that includes genetic and non‐genetic models. Among these HT animal models, Spontaneously Hypertensive Rats (SHR) with both neural and vascular alterations is the most commonly used genetic HT animal model. In this study, we investigated methodical variations among current HT animal models.

Methods

Histamine, Capsaicin, C48/80 or Substance P were administered into the femoral vein of Sprague Dawley rats or SHR to induce endothelial dysfunction. We analyzed mean arterial pressure and analyze plasma extravasation using Evans Blue dye. One way ANOVA with Bonferroni correction, and linear regression were used for statistics. Statistical significances were set at a P< 0.05.

Results

Our data showed significant negative linear regression on the degree of plasma extravasation with blood pressure changes in neurogenic inflammation but positive linear regression in immunogenic inflammation. In addition, Evans blue dye inhibited C48/80‐induccd extensive plasma extravasation, mast cell degranulation, and edema significantly.

Conclusions

We have observed significant variations among neurogenic and immunogenic inflammation induced blood pressure changes. Our data shows for the first time that methodical variations observed among animal models, can potentially translate into differential blood pressure patterns, which can be falsely taken to be biologically significant. Our study therefore highlights the pivotal need to carefully consider methodical approaches to animal models that report quantitative differences.
Antioxidant Therapy Attenuates Post‐Infarct Left Ventricular Remodeling by Driving Expression of the Transcriptional Repressor Krüppel‐Like Factor 15
Authors: Rogers Russell George , Otis Jeffrey Scott
Published: November 2023

Background

Cardiovascular disease and heart failure are responsible for approximately 33% of all‐cause mortality in the United States. The causes of heart failure following myocardial infarction (MI) are diverse, but research has implicated oxidative stress as a key pathological driving force.

Methods

MI was surgically induced following ligation of the left anterior descending coronary artery. Subgroups of MI rats received resveratrol (i.p., 10 mg/kg/day for 28 days beginning immediately post‐MI). Cardiac histology and Krüppel‐like factor 15 (KLF15) expression were analyzed.

Results

MI resulted in a significant reduction in the expression of KLF15, a transcriptional repressor to pro‐hypertrophic and pro‐fibrotic genes. Further, MI increased cardiomyocyte cross‐sectional area approximately 2‐fold compared to sham operated animals. MI rats that received resveratrol had an increased expression of nuclear factor (erythroid‐derived 2)‐like 2, a master antioxidant transcription factor that may suggest a reduction to oxidative stress. Further, resveratrol increased expression of KLF15 and attenuated infarct scar size and cardiomyocyte hypertrophy.

Conclusions

These results indicate a previously unknown redox‐sensitive mechanism to pathological remodeling following MI and suggest that therapeutic interventions targeting KLF15 signaling may improve cardiac health following MI.

Support or Funding Information

Georgia State University Internal Research Grant