bluuebunny/crossref_metadata_2025 huggingface dataset:
4-octyl itaconate ameliorate cognitive impairment in 3xTg mouse model of Alzheimer's Disease
Authors: Behera Jyotirmaya , Nasme Fariha , Zhang Yu-Ting , Smolenkova Irina , Tyagi Neetu
Published: May 2023

The most prevalent form of dementia, Alzheimer's disease (AD), is characterized by abnormal amyloid-(A) plaque accumulation, neuroinflammation, and neuronal loss. A cell-permeable derivative of itaconate called 4-octyl itaconate (OI) has recently been shown to reduce inflammation. However, the impact of OI in the 3xTg transgenic mouse model of AD is still unclear. We administered OI or saline to 3xTg-AD mice. According to our findings, OI improved cognitive functions. OI also significantly decreased brain Aβ deposition and Aβ levels, inhibited cell apoptosis, decreased hippocampal and cortical neuronal damage. Additionally, we discovered that OI decreased the levels of proinflammatory cytokines, cell apoptosis, and cognitive decline in the brains of 3xTg-AD mice while increasing the expression of the Nrf2/HO-1 signaling pathway in 3xTg-AD mice, suggesting that OI might be recognized as a promising candidate for the treatment of AD.

TPA 971566-AHA

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Systemic Mapping of Organ Plasma Extravasation Post Myocardial Infarction
Authors: Kitzerow Oliver , Suber Paul , Mohanad Shukry , Zucker Irving , Wang Hanjun
Published: May 2023

Chronic Heart failure (CHF) is a highly prevalent disease that leads to significant morbidity and mortality. Diffuse vasculopathy is a common feature of the morbidity associated with CHF. Increased vascular permeability leading to plasma extravasation (PEx) occurs in surrounding tissues following endothelial dysfunction. Such micro- and macro-vascular complications develop over time and lead to edema, inflammation, and multi-organ dysfunction in CHF. However, a systemic examination of PEx in vital organs among different time windows of CHF has never been performed before. In the present study, we investigated time-dependent PEx in several major visceral organs including heart, lung, liver, spleen, kidney, duodenum, ileum, cecum and pancreas between sham-operated and CHF rats induced by myocardial infarction (MI). Plasma extravasation was determined by evaluating Evans Blue concentrations calorimetrically at fluorescence excitation wavelength of 620 nm (bandwidth 10 nm) and an emission wavelength of 680 nm (bandwidth 40 nm) at 3 days, 8-10 weeks and 4 months following MI. Data show that heart PEx level was initially high at day 3 post MI and then gradually decreased but still remained at a moderately high level at 8-10 weeks and 4 months post MI. Lung PEx began at day 3 and remained significantly high at both 8-10 weeks and 4 months post MI. Spleen PEx level was significantly high at 8-10 weeks and 4 months but not day 3 post MI. Liver PEx occurs early at day 3 and remain significantly high at 8-10 weeks and 4 months post MI. For the gastrointestinal (GI) organs including Duodenum, ileum and cecum, there was a general trend that PEx level gradually increased following MI and reached a statistical significance at 4 months post MI. Different with GI PEx, renal PEx level was initially high at day 3 but back to normal level at 8-10 weeks post MI. However, renal PEx was significantly elevated again at 4 months post MI. In summary, we found that MI generally incites a time-dependent PEx of multiple visceral organs. However, the PEx time window for individual organ in response to the MI challenge was different, suggesting that different mechanisms might be involved in the pathogenesis of PEx in these vital organs during CHF.

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Epicore Discovery Patch® sweat collection system to assess sweat proteomics-based biomarker discovery in exercise-heat stress and acclimation
Authors: Mahoney Kyle , Chon Ki , Ghaffari Roozbeh , Minnis Mike , Huggins Robert , Lee Elaine
Published: May 2023

Purpose: To optimize sample processing workflow, test the hypothesis that sweat proteome expression is expansive and stress-specific, and to discover novel sweat biomarkers able to detect heat stress exposure and acclimation state. Methods: Men and women (n=5, 25.7±4.5 yrs, 66.7±10.5 kg, 69±4 inches, VO2max 49.5±4 ml×kg-1 ×min-1) completed 7 bouts of exercise in hot and humid conditions (40°C, 40% relative humidity). Parallel sweat samples (thigh) were collected on days 1 and 7 (HE1 and HE7, respectively) using the Epicore Discovery Patch® system and using gauze confined to the skin using Tegaderm. A subset of sweat samples were processed immediately vs. frozen for at least 24 hours prior to processing. ~30 ug of protein in 2% SDS in 0.1 M Tris HCl, pH 8 were reduced and alkylated (5 mM dithiothreitol, 20 mM iodoacetamide), acidified (2.5% (v/v) phosphoric acid), and subjected to the S-Trap protocol (ProtiFi, LLC) and digestion with porcine modified sequencing grade trypsin (Promega). Eluted peptides were dried, desalted, and submitted to mass spectrometry for proteomics analyses. Differential expression analyses were conducted with Scaffold and R. Results: Proteomics verified that immediately processed sweat samples yielded 213 more uniquely expressed proteins, but 188 shared proteins (vs. frozen >24 h) in presence/absence analyses, but only 1 significantly expressed protein (FDR<0.05) different between the two sample preservation protocols. In the exercise-heat stress experiments, 1,922 unique peptide sequences were detected for 2,774 unique spectra. Presence/absence analysis revealed 6 proteins uniquely present in HE1, 172 mutually present in both time points and 45 uniquely present in HE7. Based on the quantitative profile (p<0.05) of the 223 unique proteins, 13 were significantly expressed in HE7, including CD59 glycoprotein, heat shock-related 70 kDa protein 2, and aspartate aminotransferase, which have been previously linked to heat stress, although never in sweat. Conclusion: Protocol optimization reveals unique stability of Epicore Discovery Patch® sweat collection quantifiable by highly sensitive proteomics assays. Specific to a physiological heat acclimation over 7 days, stress response proteins such as various histone family members, and unique biomarkers such as CD59 glycoprotein, HSP72 and aspartate aminotransferase appeared in sweat samples. Our novel observations regarding sweat composition complexity and specific supports ongoing work with diverse subject populations and other stress conditions.

ONR, DoD, Faculty IDC

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
High fat-high sugar diet induces sex-dependent effects on the small intestine
Authors: Osborne Sarah , Rubin Maxwell , Ahlert John , Smith Emma , St Aubin Chaheyla , Miller Kyle , Al-Nakkash Layla
Published: May 2023

Background: Metabolic syndrome includes a plethora of symptoms ultimately leading to obesity and type 2 diabetes. Obesity has been linked to chronic gastrointestinal dysfunction (constipation, or diarrhea) and specifically females with high BMI have been associated with increased prevalence of diarrhea. We aimed to better understand the influence of high fat-high sugar diet (Western diet) on small intestinal function and to assess sex-dependent effects. Methods: We measured transepithelial short circuit current (Isc) a measure of chloride secretory function, across freshly isolated segments of jejunum from male and female C57Bl/6J mice fed a high fat high sugar diet (HFS) for 12 weeks, compared to lean controls. At the completion of the study, segments of jejunum were frozen for western blot determination of key proteins involved in secretory and absorptive functions and senescence. Intestinal morphology was assessed. Serum cytokine assays were performed. Results: Basal Isc was significantly decreased 70% ( P<0.05) in HFS both females and males versus leans. In females, the HFS-induced decrease in Isc was attributed to a significant loss of CLC2, NKCC1 and CFTR expression whereas in males the decrease in Isc was due to a significant loss of Na/K-ATPase, KCa and NKCC1 expression (indicating interesting sex-dependent etiology). A2BR levels were also dysregulated in HFS fed male and female mice. Inflammatory state and shadowed body weight changes with feeding a western diet. Assessment of intestinal morphology and metabolic profile is being further evaluated. Conclusions: Our data suggests that the reduced basal jejunal Isc in HFS mice is attributed to sex-dependent mechanisms. Improved understanding of Western diet-induced intestinal dysfunctions may provide improved drug targets to treat gastrointestinal disturbances in obesity and diabetes.

Midwestern Arizona Alzheimer’s Consortium and Diabetes Action Research and Education Foundation

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Loss Of Nicotinamide Nucleotide Transhydrogenase Promotes Redox Dependent Endothelial Activation In Atherosclerosis
Authors: Rao Shashanka , Gautier Nicole , Woolard Matthew , Orr A. Wayne , Krzywanski David
Published: May 2023

Heart disease is the leading cause of death in the United States and atherosclerosis accounts for nearly 75% of all deaths from heart disease. Atherosclerosis is a chronic inflammatory disease and mitochondrial reactive oxygen species (mtROS) are critical contributors to disease development. Nicotinamide nucleotide transhydrogenase (NNT) is a mitochondrial protein that maintains mitochondrial NADPH pools and supports the enzymatic degradation of mtROS. Preliminary data indicates that NNT expression is decreased in the endothelium of human atherosclerotic plaques and we sought to test the hypothesis that the loss of NNT increases mtROS and promotes atherosclerosis by enhancing endothelial and vascular dysfunction. Previous we have demonstrated that the loss of NNT was associated with increased vascular ROS production, plaque formation, and plaque size in response to treatment with PCSK9 and high fat diet (HFD). We now show that the loss of NNT in endothelial specific NNT knockout mice promotes enhanced endothelial VCAM-1 expression in response to HFD and disturbed flow. Similarly, in vitro, the loss of NNT promoted both VCAM-1 and ICAM-1 expression in response to oxLDL. Increased adhesion molecule expression associated with the loss of NNT also augmented monocyte adhesion in response to oxLDL consistent with vascular inflammation observed in early atherosclerosis. Additionally, macrophages isolated from NNT knockout mice display enhanced M1 polarization, decreased lipid uptake, and impaired lipid utilization. Co- treatment with the mitochondria targeted antioxidant MitoEbselen is able to normalize both endothelial and macrophage function, underscoring a critical role for mtROS in promoting an inflammatory phenotype in these cells. In both global and endothelial cell specific NNT knockout mice the loss of NNT was associated with increased necrotic core formation in response to PCSK9 treatment and 16 weeks of high fat diet. Taken together, these data indicate that decreased NNT expression promotes endothelial activation, increased inflammatory cell trafficking, macrophage metabolic dysfunction and M1 polarization that could contribute to an acceleration of necrotic core development and severe atherosclerotic disease.

NIH P20GM121307. NIH 1 R01 HL145171-01A1

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Fibroblast activation protein modulates left ventricular growth and matrix remodeling
Authors: Churillo Amelia , Freeburg Lisa , Samani Stephanie , MacLaren Janna , Saravanan Pranav , Jones Traci , Spinale Francis
Published: May 2023

Background: Fibroblast Activation Protein (FAP) is abundantly expressed in cancer associated fibroblasts and contributes to activation of proteolytic cascades which alter extracellular matrix (ECM) remodeling. However, whether and to what degree FAP influences left ventricular (LV) function and myocardial structure remains unclear. The present project tested the hypothesis that genetic ablation of FAP would modify LV structure and function in the absence of a pathological stimulus. Methods and Results: Transgenic mice with FAP gene deletion (FAPKO, C57BL/6 background, 3 months of age, n=24) and age matched wild type (WT, n=24) underwent high fidelity LV echocardiography to measure LV ejection fraction, LV end diastolic volume, and LV mass. All results are reported as mean ± SEM. While LV function (62 ± 1 vs. 65 ± 2 %) and volumes (68 ± 4 vs. 70 ± 4 μL) were within normal limits, LV mass to body weight ratio increased (4.9 ± 0.3 vs. 6.1 ± 0.5 mg/g, p<0.05) in the FAPKO mice. LV myocyte cross sectional area (CSA) (168 ± 24 vs. 210 ± 13 μm2, p<0.05) and collagen content (3.3 ± 0.3 vs. 6.1 ± 0.8%, p=0.07) measured by histomorphometry were increased in FAPKO mice. Using rtPCR, increased levels of collagen type I (1.03 ± 0.07 vs. 1.38 ± 0.19 fold change, p<0.05) and type III (1.04 ± 0.08 vs. 1.74 ± 0.26 fold change, p<0.05) were observed in the FAPKO group. Transforming Growth Factor Beta 2 (TGFβ2) (1.04 ± 0.10 vs. 0.74 ± 0.06 fold change, p<0.05) and Snail Family Transcription Repressor 1 (Snai1) (1.11 ± 0.14 vs. 0.77 ± 0.08 fold change, p<0.05) levels were significantly decreased in the FAPKO mice. Conclusion: Increased LV mass and myocyte CSA accompanied by increased collagen content and expression indicated that LV hypertrophy occurred with genetic deletion of FAP. Shifts in the TGF axis and Snai1 suggests that fibroblast endothelial-mesenchymal transition occurred in the absence of FAP. These findings demonstrated for the first time that FAP, most commonly associated with cancer associated fibroblasts, can alter LV myocardial structure.

This work was supported in part by National Institutes of Health grant R01HL130972-01A1 (F.G.S.) & R01HL5949 (F.G.S.) as well as a Merit Award from the Veterans Health Administration, BX000168-10A1 (F.G.S.) & BX005320 (F.G.S.). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Deletion of miR-92 and its cluster promotes metabolic and arterial dysfunction, and atherosclerosis
Authors: Gogulamudi Venkateswara , Kim John , Donato Anthony , Lesniewski Lisa
Published: May 2023

Atherosclerosis, the leading cause of death in the US, is a chronic inflammatory disorder that is associated with arterial dysfunction and hyperlipidemia. Dysfunction of the endothelium, a single layer of cells lining the inside of arteries, is a primary risk factor for atherosclerosis. Endothelial dysfunction is characterized by altered cell metabolism and impaired vasodilation. MicroRNAs (miRs) are small non-coding RNAs that are key regulators of metabolic and cardiovascular diseases. miR-92 has also been shown to be a modulator of endothelial function. We hypothesized that deleting miR-92 would alter endothelial cell metabolism, cause vascular dysfunction, and worsen atherosclerosis. We utilized male and female whole-body miR-92 knockout (miR-92 KO) mice. Hyperlipidemia was induced by administering a single dose of Pcsk9 containing adeno-associated virus, after which mice were fed an atherogenic diet for 16 weeks until aortas were collected to assess atherosclerotic plaque burden. We assessed measures of mitochondrial metabolism in isolated primary endothelial cells (ECs), arterial function, and aortic plaque burden. Using Seahorse technology, we found that primary ECs from miR-92 knockout mice demonstrated a 25% higher rate of oxygen consumption (p<0.02), 25% higher spare respiration (p<0.02), and 61% higher proton leak (p<0.01) compared with wild-type (WT) ECs, indicating increased oxidative phosphorylation. Endothelial-dependent dilation was lower in miR-92 KO mice response to acetylcholine (Ach, 10-9 to 10-4 M) (maximal dilation: 72.2% vs. 38.6%, p<0.001) compared with WT mice, indicative of endothelial dysfunction. miR-92 deletion also increased pulse wave velocity (272.6 vs. 297.2 cm/s, p<0.02), a measure of large artery stiffness. Percent plaque area in the aorta was higher in miR92-deficient mice compared to WT mice (1.0 vs. 2.78%, p<0.03). In conclusion, these findings suggest that deletion of miR-92 and its cluster results in a shift towards oxidative phosphorylation in the endothelium, and this is associated with impaired vascular function and a small, but significant, increase in atherosclerotic plaque development. Together, these results suggest that miR-92 may be a potential therapeutic target to improve arterial dysfunction and reduce atherosclerosis.

National Institute on Aging (R01 AG048366 and R01 AG060395) and US Department of Veterans Affairs (I01 BX004492)

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Transcriptional repression of the MRTF/SRF-cytoskeleton pathway by Rev-erba promotes beigeing via adipogenic progenitor fate switch
Authors: Xiong Xuekai , Li Weini , Kiperman Tali , Ma Ke
Published: May 2023

The circadian clock exerts temporal control in metabolic processes to maintain homeostasis, with its disruption leading to the development of obesity and insulin resistance. Adipose fibrosis in obese subjects exacerbates insulin resistance by restricting healthy tissue expansion and remodeling. Rev-erbα is a key circadian clock repressor that displays circadian rhythmic expression in adipose tissue, although its role in adipose tissue fibrosis is not known. Here we show that Rev-ebα inhibits the fibrogenic fate of adipocyte progenitors while promoting beige adipogenic potential via transcription repression of the MRTF/SRF-actin cytoskeleton axis. ChIP-seq analysis of Rev-erbα cistrome in adipogenic precursors identified its transcriptional control of pathways involved in cytoskeleton modulation, including established myofibroblast gene markers small muscle α-actin and Tropomysin. Gain-of-function of Rev-erbα in beige adipogenic precursors markedly suppressed MRTF/SRF activity with enhanced beige differentiation, while Rev-erbα silencing suppressed beige adipogenesis. Prrx1-Cre-mediated subcutaneous beige fat-selective Rev-erbα knock-in induced browning with augmented mitochondrial metabolism, resulting in increased energy expenditure, resistance to obesity and insulin sensitivity. Furthermore, single cell RNA-seq of beige progenitors with Rev-erbα overexpression revealed striking loss of preadipcyte-like (PAL) subpopulations with myofibroblastic characteristics that arise from pericyte lineage. PAL beige progenitors displayed enrichment of epithelial mesenchymal transition-related gene signature and contractile program as compared to preadipocytes. Preadipocyte population with Rev-erbα overexpression exhibited activated oxidative phosphorylation pathway with inhibition of myofibrolast characteristics. Taken together, our findings identify a novel regulatory function of Rev-erbα in modulating adipogenic progenitor fate choice that may promote adipose tissue beigeing while suppressing fibrotic complications.

NIDDK grant 1R01DK112794, 1R01DK130499 and AR-DMRI 2023 T2D Innovation Grant

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Galanin inhibition of wake-active histaminergic neurons
Authors: Michael Natalie , Khouma Axelle , Caron Alexandre , Plamondon Julie
Published: May 2023

Histaminergic neurons are a population of wake-active neurons confined to the tuberomammillary nucleus (TMN) in the posterior hypothalamus. They form a crucial component of the ‘sleep switch’ in the brain and promote arousal when activated. The histaminergic neurons are strongly innervated by ventrolateral preoptic area (VLPO) neurons expressing galanin, a neuropeptide associated with sleep promotion. While recent studies have confirmed the importance of VLPO projections to the TMN in initiating and maintaining sleep, the ability of galanin to modulate the activity of the wake-promoting histaminergic neurons of the TMN has largely been overlooked. Therefore, we aimed to determine the mechanisms by which galanin alters the electrical excitability of genetically identified histaminergic neurons. We hypothesized that galanin inhibits histaminergic neuron activity via direct post-synaptic activation of galanin 1 receptors (GalR1). Whole-cell patch-clamp electrophysiology was performed on hypothalamic brain slices from mice expressing tdTomato fluorescence in cells expressing histidine decarboxylase (HDC), the sole enzyme required for histamine synthesis (HDCCre::tdTomato mice). RNAscope® in situ hybridization was used to explore Gal1R mRNA expression in HDC expressing neurons. Whole-cell current-clamp recordings in male mice revealed that galanin (100nM) inhibits the majority of HDC neurons. The galanin-induced inhibition was associated with a hyperpolarization of the membrane potential and a decrease in firing frequency. Consistent with our hypothesis, a selective galanin 2 receptor (Gal2R) agonist (M1145 - 200nM) had no effect on male HDC neuron activity. RNAscope® studies in male mice revealed co-expression of Gal1R mRNA in a large proportion of HDC-expressing neurons. Interestingly, the galanin-induced inhibition of HDC neuron electrical excitability was less pronounced in female mice. Overall, our data point to an important role of post-synaptic Gal1Rs expressed on histaminergic neurons in mediating galanin’s inhibitory effects in the TMN. Our data also suggest that sex differences exist in histaminergic neuron responsiveness to galanin. These findings are consistent with the idea that some of the sleep promoting effects of VLPO neuron activation occur through galanin’s ability to inhibit the wake-active histaminergic neurons.

Sleep Research Society (SRS), Canada First Research Excellence Fund (Sentinel North Partnered Research Chair in Sleep Pharmacometabolism), Fondation Institut Universitaire de Cardiologie et de Pneumologie de Quebec (FIUCPQ), Fonds de recherche de Quebec - Sante (FRQS).

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Aging Is Associated with a Circulating Endothelial Cell-Derived Microvesicle Phenotype that Impairs Cerebral Fibrinolytic Capacity
Authors: Berry Auburn , Garcia Vinicius , Wegerson Kendra , Cardenas Hannah , Ostrander Emily , Fandl Hannah , Greiner Jared , Stauffer Brian , DeSouza Christopher
Published: May 2023

Aging is associated with increased risk and prevalence of ischemic stroke. Endothelial cell dysfunction is considered to be a central mechanism underlying the age-related increase in cerebrovascular accidents (CVA). However, the direct, and indirect, effects of aging on endothelial cell biology are diverse and not completely understood. Reduced endogenous fibrinolytic activity is a central etiologic factor underlying ischemic stroke. Endothelial cells are the primary site of synthesis and release of tissue-type plasminogen activator (t-PA), the main plasminogen activator in fibrinolysis and central regulator. Clinical interest in circulating extracellular vesicles, particularly endothelial cell-derived microvesicles (EMVs), has intensified due to their involvement in the development and progression of endothelial dysfunction and CVA. The aim of this study was to determine, in vitro, the effect of circulating EMVs isolated from young and older adults on brain endothelial cell fibrinolytic capacity. We hypothesized that EMVs from older adults would reduce brain endothelial cell t-PA production and release and increase PAI-1 production compared with EMVs from young adults. Twenty-two healthy, non-obese, normotensive, sedentary adults were studied: 10 young (6M/4F; age: 25±1 yr) and 12 older (7M/5F; 64±2 yr). EMV identification (CD144+) and isolation from peripheral blood were performed by flow cytometry. Human cerebral microvascular endothelial cells (hCMECs) were cultured and separately treated with EMVs from each subject. Cultured hCMECs were treated with EMVs in the absence and presence of thrombin (1 unit/mL) for 24 hours. Basal expression of t-PA (25.2±1.5 vs 39.8±1.8 AU) and the t-PA response to thrombin (32.5±1.5 vs 57.2±2.2 AU) were significantly lower (~35%) in hCMECs treated with EMVs from older compared with young adults. Concordant with changes in cell protein expression, basal t-PA production (55.2±3.5 vs 70.1±3.7 ng/mL) and thrombin-stimulated t-PA production (61.9±3.7 vs 88.4±3.8 ng/mL) was significantly lower in cells treated with EMVs from older adults. In conclusion, circulating EMVs may contribute to the increased risk of ischemic stroke with aging by impairing brain endothelial cell fibrinolytic capacity. Diminished capacity of the endothelium to release t-PA is a key mechanistic factor underlying cerebral thrombosis.

Nothing to Disclose

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Renoprotective and anti-inflammatory effects of growth differentiation factor 15 (GDF15) in mice with diet-induced obesity
Authors: Zheng Hong , Liu Xuefei , Boomer Shane
Published: May 2023

Growth differentiation factor 15 (GDF15) is a stress-responsive cytokine studied recently for its role in multiple biological processes and diseases. This transforming growth factor beta (TGF-b) family member has been investigated as a therapeutic agent and biomarker for obesity and associated cardiovascular diseases. Studies have shown the anti-inflammation, anti-obesity, and anti-diabetic effects of GDF15, but few have focused on the role of GDF15 in the kidneys. In this study, we hypothesized that GDF15 ameliorates obesity-induced inflammation and fibrosis in the kidney. We treated wild-type (WT) and GDF15 transgenic (NAG) mice with high-fat diets (HFD) (42% calories from fat) or normal chow. Analysis of four groups of mice (WT, WT+HFD, NAG, and NAG+HFD) illustrated significantly reduced levels of kidney fibrosis (a-SMA, TGF-b) and inflammation (NFkB, TNF-a) in the NAG with HFD mice. The kidney injury markers NGAL and TIM-1 were significantly reduced in the NAG+HFD mice. We also found decreased urinary norepinephrine excretion and serum creatinine, and increased glomerular filtration rate, urine volume, and sodium excretion in GDF15 transgenic mice with HFD. Further, in vitro study showed that GDF15 treatment reduced norepinephrine-induced kidney fibrosis and pro-inflammatory cytokine production in cultured kidney HK-2 and LLC cells. These results suggest GDF15 is a possible therapeutic target for kidney injury via its anti-inflammatory and anti-fibrosis protective effects.

Funded by NIH R01-DK-114663 & R01-DK-129311

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Investigating vitamin D insufficiency in claudin-2 and claudin-12 knockout mice
Authors: Young Kennedi , Alexander R. Todd
Published: May 2023

Infants and children require a net positive calcium (Ca2+) balance to achieve optimal bone mineral density by early adulthood. Active vitamin D (calcitriol) increases blood Ca2+ levels by increasing intestinal absorption and renal reabsorption of Ca2+ as well as bone remodelling. In both the kidney and intestine, Ca2+ is absorbed both paracellularly, through claudin proteins that make up the tight junction, and transcellularly, through Ca2+ specific transporters and channels. Claudins-2 and -12 are tight junction proteins that mediate Ca2+ permeability across renal and intestinal cell culture epithelial layers. Claudin-2 and claudin-12 double knockout (DKO) mice have a perturbed Ca2+ balance resulting in hypocalcemia, hypercalciuria and decreased bone mineralization. Interestingly, DKO mice did not have increased calcitriol levels or upregulation of Cyp27b1 (the key enzyme regulating serum calcitriol levels), despite a significant increase in serum parathyroid hormone (PTH) levels and decreased serum Ca2+ compared to wild-type mice. We hypothesize therefore that claudin-2 and/or claudin-12 are necessary for optimal PTHR1 signalling to increase Cyp27b1 expression, and thus calcitriol production in the proximal tubule (PT). To address this, we first administered wild-type and double knockout mice calcitriol and found that they could increase their blood calcium levels, though not to the same extent as WT, consistent with the DKO animals not having vitamin D resistance. Next we put wild-type and DKO animals on a low calcium diet. The DKO mice were able to increase their serum calcitriol levels and Cyp27b1 expression under these conditions, consistent with attenuated regulation and not abolition of PTHR1 signalling. Next we examined PTHR1 signaling in HEK-293 cells and a CYP27B1 reporter construct. We found that in HEK cells, PTH treatment results in increased expression of the CYP27B1 promoter construct, and that claudin-2 expression alone, increased promoter expression to the same extent as PTH. Additionally, calcitriol suppressed CYP27B1 promoter expression, however this suppression was abolished when claudin-2, but not claudin-12, was expressed. In primary mouse proximal tubule cells, PTH significantly increased Cyp27b1 mRNA expression compared to controls. In future experiments we will investigate the effects of claudin-2 and/or claudin-12 on PTH-induced Cyp27b1 mRNA expression using primary proximal tubule cells from claudin-2, claudin-12 or claudin-2/12 DKO mice. This work will tease out the role of the proximal tubule tight junction proteins claudin-2 and -12 in regulating calcitriol levels.

Funding: Alberta Innovates, NSERC and CIHR

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Free fatty acid exacerbates diabetic kidney injury by suppressing autophagy-lysosomal function via ER stress
Authors: Zhao Xueying , George Jasmine
Published: May 2023

Diabetic kidney disease (DKD), the leading cause of chronic kidney disease, is characterized by accumulation of renal tubule free fatty acids (FFAs) and triglyceride (TG)-enriched lipid droplets (LDs) and cell death. The present study aimed to investigate how FFA or TG induces renal tubular cell apoptosis, thereby contributing to the progression of DKD. Cell studies were conducted to define the causal role and underlying mechanism of FFA-activated ER stress and organelle dysfunction in tubular cell injury. Six-week-old wild-type (WT) and eNOS-deficient C57BL/6J mice were placed on normal diet (ND, 5% fat calories) or high-fat diet (HFD, 42% fat calories) for two weeks, and then rendered diabetic with alloxan. Alloxan injection resulted in equivalent hyperglycemia in ND and HFD-fed WT and eNOS-deficient mice. However, a massive increase in urinary albumin was observed in HFD plus alloxan-treated eNOS-deficient mice, which was accompanied by excessive accumulation of neutral lipids in damaged proximal tubules. Moreover, in the diabetic eNOS-deficient kidneys, HFD feeding resulted in suppression of autophagy-lysosomal function and increase in tubular cell apoptosis. Cell studies revealed that saturated FFA palmitate but not unsaturated oleate induced eukaryotic initiation factor (eIF)2α phosphorylation, and then stimulated the activating transcription factor (ATF)4 and C/EBP homologous protein (CHOP), which, in turn, impaired autophagy-lysosomal function, leading to cell apoptosis. In addition, we observed a dramatic upregulation of LD-associated protein ADRP expression and TG-enriched LD formation in oleate-treated renal tubular cells, which was not apparent in palmitate-treated ones. Together, this study demonstrates that accumulation of renal FFA, rather than TG, plays a crucial role in the pathogenesis of diabetic kidney injury by suppressing autophagy-lysosomal function through ER stress signaling.

This work was supported by the National Institutes of Health Grants SC1DK112151 and S21MD000101.

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Macrophage-specific EphB2 Deficiency Mitigates Nonalcoholic Steatohepatitis-fibrosis in Mice
Authors: Kamdem Donald Severin , Egal Erika , Pellizzari Sarah , Pham Tuam , Evason Kimberley , Boudina Sihem , Henkemeyer Mark , Beaudin Anna , Mimche Patrice
Published: May 2023

Background & Aims: Emerging evidence suggests that the receptor tyrosine kinase EphB2 regulates tissue inflammation and fibrosis. However, its contribution to non-alcoholic fatty liver disease/non-alcoholic steatohepatitis (NAFLD or NASH) remains largely unknown; thus, we aimed to determine its role. Methods: In NAFLD/NASH patients, hepatic EphB2 and serum EphrinB2 ligands were evaluated. Disease phenotyping was performed in male and female wild type (WT), EphB2-/-, EphB2-kinase-dead (EphB2K661R), EphB2-kinase-overactive (EphB2F620D) mice, and in macrophage-specific EphB2-/- mice fed the obesogenic Gubra-Amylin NASH diet for 22-28 weeks and the Choline Deficient Amino-acid improved high-fat diets for 10-12 weeks. The role of EphB2 in inflammation was investigated in bone marrow-derived macrophages. Pharmacological inhibition of EphB2 for the treatment of NASH was also evaluated in vivo. Histology, hydroxyproline assay, flow cytometry, gene expression, biochemical assays, and RNA sequencing were used to dissect the molecular mechanism underlying macrophages’ EphB2 function in NASH. Results: Hepatic EphB2 was strongly upregulated in NASH patients and correlated with NASH fibrosis score. Serum EphrinB2 was also elevated in NASH patients. In mouse models of NASH, EphB2-/- mice showed a significant reduction in liver steatosis, inflammation, and fibrosis compared to WT mice. This is supported by a significant reduction of liver fat content, pro-inflammatory and fibrotic genes in EphB2-/- compared to WT mice. EphB2 forward signaling is likely the main driver of NASH progression as depicted by the significant increase in steatosis, inflammation, and fibrosis observed in EphB2F620D compared to WT and EphB2K661R mice. Flow cytometry revealed a reduced macrophage population in EphB2-/- mice compared to WT mice.In addition, bone marrow-derived macrophages from EphB2-/- mice showed reduced inflammation when stimulated with LPS in vitro. Interestingly, macrophage-specific EphB2-/- showed a reduction of NASH fibrosis and associated metabolic syndrome. Conclusions: We have identified EphB2 as a key player in the pathogenesis of fatty liver disease in humans and mice and its therapeutic targeting could potentially mitigate NASH fibrosis and associated metabolic syndrome

National Institutes of Health (NIH)

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Role of mitochondrial PKD on right ventricular fibrosis under pulmonary hypertension
Authors: Nieto Bridget , O-Uchi Jin , Cypress Michael , Landherr Maria , Chaput Isabel , Polina Iuliia , Suckow Mark , Jhun Bong Sook
Published: May 2023

Introduction: Growing evidence suggests a link between right ventricular (RV) fibrosis, poor function of the pressure-overloaded RV, and mortality in pulmonary arterial hypertension (PAH). However, there are no currently available therapies that specifically target RV fibrosis. Using RV tissues from a preclinical rat PAH model, we previously reported that activation of stress-responsive protein kinase D (PKD) and phosphorylation of its substrate dynamin-related protein 1 (DRP1) occur specifically at the outer mitochondrial membrane (OMM) of RV cardiac fibroblasts (RV-CFs), but not in RV myocytes. RV-CFs isolated from PAH rats exhibited increased mitochondrial fission, mitochondrial reactive oxygen species (mROS), and proliferative signaling compared to RV-CFs from control animals, suggesting an association between PKD signaling in RV-CFs and RV fibrosis. Hypothesis: Inhibition of mitochondrial PKD signaling in CFs can attenuate RV fibrosis in PAH. Methods: Primary adult CFs from human ventricles were used for in vitro assays. A preclinical rat PAH model (Sugen 5416 injection and 3-week hypoxia followed by 4-week normoxia) was used for in vivo assays. Results: To specifically inhibit PKD activity at the OMM, an OMM-targeted dominant-negative PKD1 (mt-PKD-DN) was generated by adding an OMM-target sequence (amino acid 1-33 from human TOM20) at the N-terminus of PKD1-K612W. We confirmed that mt-PKD-DN is specifically expressed in mitochondria and decreases basal PKD activity only in mitochondria, assessed by protein fractionation. Importantly, mt-PKD-DN was able to inhibit mitochondrial fission, reduce mROS, hyperpolarize mitochondrial membrane potential, and ultimately decrease CF proliferation in vitro. To inhibit mitochondrial PKD activity in quiescent and resident CFs in vivo, we next administrated CF-selective adeno-associated virus serotype 9 (AAV9) carrying human TCF21 (hTCF21) promoter and mt-PKD-DN into the rat PAH model by tail vein injection. Introduction of AAV9-hTCF21-mt-PKD-DN or its control virus did not significantly alter baseline cardiac function. CF-specific mt-PKD-DN expression was able to significantly reduce RV hypertrophy/fibrosis, and RV-CF hyperproliferation as assessed by immunostaining of a nucleus-localized marker of active cell proliferation Ki67. Lastly, we found the partial recovery of in vivo RV function (i.e., recovery of tricuspid annular plane systolic excursion in echocardiography) in PAH rats with mt-PKD-DN. Conclusion: Targeting mitochondrial PKD may be a potential therapeutic strategy to reduce cardiac fibrosis under pathological conditions including PAH.

R01HL136757 (to J.O.-U), AHA 18CDA34110091 (to B.S.J)

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Caveolin-3 Nitrative Modification: A Novel Mechanism of Cardiac Insulin Resistance in Pre-Diabetic Animals
Authors: Wang Yajing , Zhao Jianli , Meng Zhijun , Zhang Zhen , Liu Caihong , Gao Erhe , Lopez Bernard , Christopher Theodore , Koch Walter , Ma Xinliang
Published: May 2023

Rationale: Diabetes-induced myocardial insulin resistance leads to cardiac injury. There is, however, no consensus on the underlying molecular mechanisms. Studies have demonstrated that diabetic hearts are resistant to other cardioprotective interventions, such as adiponectin and preconditioning. In the face of multiple therapeutic interventions, the “universal” resistance suggests the impairment of the requisite molecule(s) involved in broad pro-survival signaling cascades. Caveolin (Cav) sits on cellular membrane and coordinates transmembrane signaling. It remains unknown whether Cav3 contributes to diabetic ischemic heart failure (HF) and impaired cardiac protective signaling. Methods and Results: Mice were fed a normal diet (ND) or high-fat diet (HFD) for 2-12 weeks and subjected to myocardial ischemia and reperfusion. At four weeks of HFD feeding (pre-diabetes), insulin's cardioprotective effect was significantly blunted compared with the ND group, when insulin signaling molecules were unchanged. However, Cav3/IRβ complex formation, a prerequisite for insulin transmembrane signaling, was significantly reduced. Cav3 tyrosine nitration is prominent in the pre-diabetic heart among various post-translational modifications altering protein/protein interaction. By nitrating cardiomyocytes with SIN-1, signalsome complexes are reduced and insulin transmembrane signalling is blocked. It was determined that Cav3 nitrates at Tyr73 using mass spectrometry. A phenylalanine substitution of Tyr73 (Cav3Y73F) abolished SIN-1 induced Cav3 nitration, restored the Cav3/IRβ complex, and rescued insulin transmembrane signaling. Furthermore, cardiomyocyte-specific Cav3Y73F reexpression blocked HFD-induced Cav3 nitration, preserved Cav3 signalsome integrity, restored transmembrane signaling, and restored insulin's protective effect against ischemic HF in mice. As a result of diabetic nitrative modification at Tyr73 of Cav3, the formation of Cav3/AdipoR1 complexes and the function of adiponectin for cardioprotection are also reduced. Conclusion: In pre-diabetic hearts, nitration of Cav3 at Tyr73 leads to signal complex dissociation that leads to cardiac insulin/adiponectin resistance, contributing to the progression of ischemic heart failure. Developing early interventions geared toward preserving Cav3-centered signalsome integrity may prove effective against diabetic exacerbation of ischemic heart failure.

there is no disclosure

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Reduction in Arterial Stiffness Is Related to Exercise Intensity
Authors: Lima Natalia , Lima Natalia , Jackson Ronald , Sherman Sara , Hibner Brooks , Fernhall Bo , Baynard Tracy , Clifford Philip
Published: May 2023

Increased arterial stiffness is associated with cardiovascular risk and mortality. Central and peripheral arterial stiffness measured with pulse wave velocity (PWV) are known to be reduced 5 min after a single bout of dynamic exercise using a large muscle mass. The effect of small muscle mass rhythmic handgrip exercise on peripheral stiffness is unknown. In addition, it is not known whether the magnitude of reduction in peripheral arterial stiffness is related to the intensity of exercise. We hypothesized that a higher exercise intensity would result in a larger reduction in post-exercise peripheral arterial stiffness. Eight healthy young volunteers participated in this study (5 females, 28 ± 4 yrs, mean ± SD). Two Millar tonometers were placed simultaneously on the brachial and radial arteries of the exercising arm for measurement of peripheral arterial stiffness. Beat-by-beat arterial pressure was obtained by a photoplethysmographic sensor on the middle finger of the contralateral hand. Brachial-radial PWV and mean arterial pressure (MAP) were recorded before exercise then at 5-, 15-, and 30-min post-exercise. The exercise consisted of two 5-min bouts of rhythmic handgrip exercise (2sec contraction/2sec relaxation) at either 30% or 50% of their maximal voluntary contraction (MVC) performed in randomized order. Baseline brachial-radial PWV before handgrip exercise at 30% MVC was 10.7 ± 2.8 m/sec. Postexercise at 30% MVC, PWV was 9.6±2.6 m/sec at 5min, 9.8 ± 2.7 m/sec at 15min, and 11.5 ± 2.9 m/sec at 30 min (all p>0.05 compared to baseline). Before handgrip exercise at 50% MVC baseline brachial-radial PWV was 13.1 ± 3.2 m/sec. Post-exercise at 50% MVC, PWV was 9.9 ± 3.7 m/sec at 5min (p<0.05), 9.1 ± 2 m/sec at 15min (p<0.05), and 10.2 ± 3 m/sec at 30 min (p>0.05). MAP was not statistically significantly different across all time points (p > 0.05). These results show that peripheral arterial stiffness measured as brachial-radial PWV was reduced after 5-min and 15 min of rhythmic handgrip exercise at 50% MVC, but not at 30% MVC. Thus, the magnitude of reduction in PWV was related to the intensity of exercise. The observed reduction of brachial-radial PWV was not a function of changes in blood pressure which would have confounded the PWV results. This study is the first to show that small muscle mass handgrip exercise reduces peripheral PWV.

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Role of caspase-1 and AIM2 inflammasome in ischemia/reperfusion injury of myocardium
Authors: Senger Nathalia , Vieira-Junior Denival , Mota Joice , Marinho Claudio , Barreto-Chaves Maria Luiza
Published: May 2023

Acute myocardial infarction induces a sterile inflammatory response, leading to cardiomyocyte damage and adverse cardiac remodeling. The contribution of inflammasomes has been involved to the cardiac remodeling, however, little is known about its potential role in cardiac hypoxia, especially the AIM2 inflammasome. Thus, the present study aimed to investigate the impact of AIM2-inflammasome absence in the myocardial susceptibility to ischemia/reperfusion (I/R) injury. For this purpose, 3-month-old male mice knockout mice for caspase-1 ( casp-/-) or AIM2 ( aim2 -/-) were used (n=5). Cardiac injury was induced in isolated heart using the ex vivo Langendorff perfusion model (20 minutes of global ischemia and 45 minutes of reperfusion). All protocols were approved by the Ethics Committee on Animal Experimentation of ICB-USP (n05402181121). Casp-/- and aim2 -/- mice showed no significant differences in heart weight to tibia length ratio when compared to wild-type mice ( WT). Supporting these results, the cardiomyocyte area, evaluated on histological slides stained with WGA (wheat germ agglutinin), was similar in all groups. In relation to functional data, post-ischemic recovery of cardiac function was similar between aim2 -/- and WT mice. However, casp-/- mice showed worse recovery after I/R, as evidenced by decreased left ventricular developed pressure (LVDP) (mmHg) and increased resistance in ventricular relaxation (TAU index). In conclusion, we provide evidences that caspase-1 is involved in myocardial susceptibility to ischemia/reperfusion (I/R) injury. Additional experiments are being conducted to increase the number of animals and to evaluate other parameters as cardiomyocyte death.

FAPESP (grants number: 2019/17031-2 and 2022/0084-0).

This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.