Transgenic Mice Research Articles

Encapsulated lactiplantibacillus plantarum improves Alzheimer’s symptoms in APP/PS1 mice

BackgroundAlzheimer’s disease (AD) is a neurodegenerative disorder that can result in neurotoxicity and an imbalance in gut microbiota. Probiotics have been shown to play an important role in regulating the gut microbiota, but their viability and bioactivity are often compromised as they traverse the gastrointestinal tract, thereby reducing their efficacy and limiting their clinical utility.ResultsIn this work, layer-by-layer (LbL) encapsulation technology was used to encapsulate Lactiplantibacillus plantarum (LP) to improve the above shortcomings. Studies in APPswe/PS1dE9 (APP/PS1) transgenic mice show that LbL-encapsulated LP ((CS/SP)2-LP) protects LP from gastrointestinal damage while (CS/SP)2-LP treatment It improves brain neuroinflammation and neuronal damage in AD mice, reduces Aβ deposition, improves tau protein phosphorylation levels, and restores intestinal barrier damage in AD mice. In addition, post-synaptic density protein 95 (PSD-95) expression increased in AD mice after treatment, indicating enhanced synaptic plasticity. Fecal metabolomic and microbiological analyzes showed that the disordered intestinal microbiota composition of AD mice was restored and short-chain fatty acids (SCFAs) levels were significantly increased after (CS/SP)2-LP treatment.ConclusionOverall, the above evidence suggests that (CS/SP)2-LP can improve AD symptoms by restoring the balance of intestinal microbiota, and (CS/SP)2-LP treatment will provide a new method to improve the symptoms of AD patients.

Berberine potentiates liver inflammation and fibrosis in the PI*Z hAAT transgenic murine model

Background Alpha-1 antitrypsin deficiency (AATD) is an inherited disease, the common variant caused by a Pi*Z mutation in the SERPINA1 gene. Pi*Z AAT increases the risk of pulmonary emphysema and liver disease. Berberine (BBR) is a nature dietary supplement and herbal remedy. Emerging evidence revealed that BBR has remarkable liver-protective properties against various liver diseases. In the present study, we investigated the therapeutic effects and toxicities of BBR in Pi*Z hepatocytes and Pi*Z transgenic mice. Methods Huh7.5 and Huh7.5Z (which carries the Pi*Z mutation) cells were treated with different concentrations of BBR for 48 hours. MTT was performed for cell viability assay. Intracellular AAT levels were evaluated by western blot. In vivo studies were carried out in wild type, native phenotype AAT (Pi*M), and Pi*Z AAT transgenic mice. Mice were treated with 50 mg/kg/day of BBR or solvent only by oral administration for 30 days. Western blot and liver histopathological examinations were performed to evaluate therapeutic benefits and liver toxicity of BBR. Results BBR reduced intracellular AAT levels in Huh7.5Z cells, meanwhile, no Pi*Z-specific toxicity was observed. However, BBR did not reduce liver AAT load but significantly potentiated liver inflammation and fibrosis accompanying the activation of unfolded protein response and mTOR in Pi*Z mice, but not in wild type and Pi*M mice. Conclusions BBR exacerbated liver inflammation and fibrosis specifically in Pi*Z mice. This adverse effect may be associated with the activation of unfolded protein response and mTOR. This study implicates that BBR should be avoided by AATD patients.

The mechanism and consequences of amyloid-β modulating thiamine pyrophosphokinase-1 expression in microglia.

Ample studies attribute cognitive decline in Alzheimer's disease to amyloid-β deposition 1-6 . However, brain amyloid-β accumulation that saturates years before the manifestation of clinical symptoms is dissociated with cognitive decline of the disease 7 . It is unknown how these two processes are mechanistically linked. In this and our accompanied study, we report that thiamine pyrophosphokinase-1 (TPK) deficiency plays essential roles in both processes via distinct mechanisms. Here we describe that diminished microglia Tpk controls the propagation of amyloid-β plaques. In APP/PS1 transgenic mice, microglia showed elevated Tpk expression at 2-month-old, but reduction in a plaque-centric manner at 8-month-old. Interestingly, lipopolysaccharide, but not amyloid-β, induceed Tpk reduction in cultured microglia. Tpk reduction led to microglia dysfunction, showing volatile motility but reduced phagocytosis and weak response to focal tissue injury, with accumulation of intracellular lipid droplets and abnormal mitochrondria. In Alzheimer's disease mice, microglia-specific knockout of Tpk caused diminished plaque coverage, exacerbated plaque burden and synaptic loss. However, increased plaques were not accompanied by the development of neurofibrillary tangles or brain atrophy, in contrast to the phenotype described in our accompanied paper with neuronal Tpk deletion. In conclusion, plaque-induced inflammation reduces Tpk in microglia, selectively exacerbating the spread of amyloid pathology.

Laminar specificity and coverage of viral-mediated gene expression restricted to GABAergic interneurons and their parvalbumin subclass in marmoset primary visual cortex.

In the mammalian neocortex, inhibition is important for dynamically balancing excitation and shaping the response properties of cells and circuits. The various computational functions of inhibition are thought to be mediated by different inhibitory neuron types, of which a large diversity exists in several species. Current understanding of the function and connectivity of distinct inhibitory neuron types has mainly derived from studies in transgenic mice. However, it is unknown whether knowledge gained from mouse studies applies to the non-human primate, the model system closest to humans. The lack of viral tools to selectively access inhibitory neuron types has been a major impediment to studying their function in the primate. Here, we have thoroughly validated and characterized several recently developed viral vectors designed to restrict transgene expression to GABAergic cells or their parvalbumin (PV) subtype, and identified two types that show high specificity and efficiency in marmoset V1. We show that in marmoset V1, AAV-h56D induces transgene expression in GABAergic cells with up to 91-94% specificity and 79% efficiency, but this depends on viral serotype and cortical layer. AAV-PHP.eB-S5E2 induces transgene expression in PV cells across all cortical layers with up to 98% specificity and 86-90% efficiency, depending on layer. Thus, these viral vectors are promising tools for studying GABA and PV cell function and connectivity in the primate cortex.

Laminar specificity and coverage of viral-mediated gene expression restricted to GABAergic interneurons and their parvalbumin subclass in marmoset primary visual cortex

In the mammalian neocortex, inhibition is important for dynamically balancing excitation and shaping the response properties of cells and circuits. The various computational functions of inhibition are thought to be mediated by different inhibitory neuron types, of which a large diversity exists in several species. Current understanding of the function and connectivity of distinct inhibitory neuron types has mainly derived from studies in transgenic mice. However, it is unknown whether knowledge gained from mouse studies applies to the non-human primate, the model system closest to humans. The lack of viral tools to selectively access inhibitory neuron types has been a major impediment to studying their function in the primate. Here, we have thoroughly validated and characterized several recently developed viral vectors designed to restrict transgene expression to GABAergic cells or their parvalbumin (PV) subtype, and identified two types that show high specificity and efficiency in marmoset V1. We show that in marmoset V1, AAV-h56D induces transgene expression in GABAergic cells with up to 91–94% specificity and 79% efficiency, but this depends on viral serotype and cortical layer. AAV-PHP.eB-S5E2 induces transgene expression in PV cells across all cortical layers with up to 98% specificity and 86–90% efficiency, depending on layer. Thus, these viral vectors are promising tools for studying GABA and PV cell function and connectivity in the primate cortex.

Cell transplantation-mediated dystrophin supplementation efficacy in Duchenne muscular dystrophy mouse motor function improvement demonstrated by enhanced skeletal muscle fatigue tolerance

BackgroundDuchenne muscular dystrophy (DMD) is an incurable neuromuscular disease leading to progressive skeletal muscle weakness and fatigue. Cell transplantation in murine models has shown promise in supplementing the lack of the dystrophin protein in DMD muscles. However, the establishment of novel, long-term, relevant methods is needed to assess its efficiency on the DMD motor function. By applying newly developed methods, this study aimed to evaluate the functional and molecular effects of cell therapy-mediated dystrophin supplementation on DMD muscles.MethodsDystrophin was supplemented in the gastrocnemius of a 5-week-old immunodeficient DMD mouse model (Dmd-null/NSG) by intramuscular xenotransplantation of healthy human immortalized myoblasts (Hu5/KD3). A long-term time-course comparative study was conducted between wild-type, untreated DMD, and dystrophin supplemented-DMD mouse muscle functions and histology. A novel GO-ATeam2 transgenic DMD mouse model was also generated to assess in vivo real-time ATP levels in gastrocnemius muscles during repeated contractions.ResultsWe found that 10.6% dystrophin supplementation in DMD muscles was sufficient to prevent low values of gastrocnemius maximal isometric contraction torque (MCT) at rest, while muscle fatigue tolerance, assessed by MCT decline after treadmill running, was fully ameliorated in 21-week-old transplanted mice. None of the dystrophin-supplemented fibers were positive for muscle damage markers after treadmill running, with 85.4% demonstrating the utilization of oxidative metabolism. Furthermore, ATP levels in response to repeated muscle contractions tended to improve, and mitochondrial activity was significantly enhanced in dystrophin supplemented-fibers.ConclusionsCell therapy-mediated dystrophin supplementation efficiently improved DMD muscle functions, as evaluated using newly developed evaluation methods. The enhanced muscle fatigue tolerance in 21-week-old mice was associated with the preferential regeneration of damage-resistant and oxidative fibers, highlighting increased mitochondrial activity, after cell transplantation. These findings significantly contribute to a more in-depth understanding of DMD pathogenesis.

Effect of Gold Nanoparticles on Growth Characteristics of Mouse Gastric Stem Cells in Vitro

ABSTRACT Gold nanoparticles (NPs) have been recently utilized in several applications of stem cells. In this study, mouse gastric stem/progenitor (mGS) cells established from a transgenic mouse model were treated by gold NPs of 60, 80, and 100 nm diameters. Cells were analyzed after 24, 48, 72, and 96 hours of incubation. Electron microscopic examination revealed the uptake of gold NPs by the mGS cells. The cellular viability and proliferation were investigated using propidium iodide, neutral red and PicoGreen Assays. The results demonstrated the viability and proliferation of mGS cells following exposure to gold NPs. While 100 nm gold NPs slightly reduced the mGS cell viability, 60 nm gold NPs at concentration of 0.07% slightly enhanced the proliferation of mGS cells more than the gold NPs at concentrations of 0.14% and 0.21%. In contrast, 80 nm gold NPs at concentration of 0.14% have promoted the proliferation of mGS cells. In conclusion, these findings offer a new perspective for the application of gold NPs and stem cells in nanomedicine and tissue engineering.

Social isolation impairs cognition via Aβ-mediated synaptic dysfunction

Social isolation (SI) is a common phenomenon in the modern world, especially during the coronavirus disease 2019 pandemic, and causes lasting cognitive impairments and mental disorders. However, it is still unclear how SI alters molecules in the brain and induces behavioural dysfunctions. Here, we report that SI impairs cognitive function and induces depressive-like behaviours in C57BL/6 J mice, in addition to impairing synaptic plasticity and increasing the levels of APP cleavage-related enzymes, thereby promoting Aβ production. Moreover, we show that in APP/PS1 transgenic mice, SI accelerates pathological changes and behavioural deficits. Interestingly, downregulation of the expression of the BACE1 attenuates SI-induced Aβ toxicity and synaptic dysfunction. Furthermore, early intervention with BACE1 shRNA blocks SI-induced cognitive impairments. Together, our data strongly suggest that SI-induced upregulation of BACE1 expression mediates Aβ toxicity and induces behavioural deficits. Down-regulation of BACE1 may be a promising strategy for preventing SI-induced cognitive impairments.

Pathways to precision medicine: deciphering the secrets of physiological and pathological atrial enlargement.

Cardiac functional, morphological, and histological analysis, coupled with liquid chromatography and mass spectrometry, of two transgenic mouse models with cardiomyocyte-specific overexpression of insulin-like growth factor 1 receptor (IGF1R) or a dominant-negative PI3K mutant (DCM-dnPI3K) revealed distinctive functional and molecular profiles during physiological (driven by IGF1R overexpression) and pathological (driven by dn-PI3K overexpression) atrial remodeling. The current study confirmed previously reported findings, including ventricular dilatation and enhanced systolic function with no evidence of arrhythmia in IGF1R model, as well as ventricular hypertrophy and decreased systolic function with intermittent atrial fibrillation in DCM-dnPI3K model. Novel findings obtained from the left atrial (LA) characterization of female mice revealed that physiological atrial enlargement resulted from increased atrial myocyte size and was associated with preserved atrial function, as determined by maintained LA ejection fraction (EF). The proteomic profile of IGF1R transgenic (Tg) mice was enriched for metabolic remodeling and showed a protein expression pattern similar to that of healthy human atria; on the other hand, pathological atrial enlargement resulted from increased atrial fibrosis with normal myocyte size and was associated with impaired atrial function due to a reduced LA EF. The proteomic profile of DCM-dnPI3K mice was enriched to both metabolic and structural remodeling and showed a protein expression pattern similar to that of human AF atria.

Isoflurane Titration Improves Detection of Hippocampal Lactate by 1H-MRS

Abstract Lactate has increasingly been recognized as both an important fuel source and signaling molecule within the brain. Alterations in brain lactate levels are associated with various neurological diseases. Thus, there is great interest in the in vivo detection and measurement of cerebral lactate levels in animals used for investigation of normal brain function and models of disease. Proton magnetic resonance spectroscopy (1H-MRS) is a non-invasive technique used to measure lactate and other metabolites within the brain. However, lactate can be difficult to detect with conventional 1H-MRS due to its low abundance and spectral overlap with lipids. In addition, volatile anesthetics used during image acquisition increase lactate production, potentially masking any subtle physiological changes in lactate levels. Here we made use of a transgenic mouse model in which expression of lactate dehydrogenase A (Ldha), the rate-limiting enzyme of lactate production, was induced within cortical and hippocampal neurons. Unexpectedly, 1H-MRS analysis under typical isoflurane-induced anesthesia of 4% induction followed by 1.6-2% maintenance, revealed no significant elevation of hippocampal lactate levels in neuronal Ldha induction mice compared to control mice. In contrast, 1H-MRS analysis using an isoflurane titration protocol in which mice were sequentially exposed to 1.6%, 2%, then finally 3% isoflurane, revealed significantly higher hippocampal lactate levels in Ldha transgenic mice compared to controls. In addition, significantly fewer mice were required to detect differences in lactate levels using the isoflurane titration protocol compared to conventional isoflurane-induced anesthesia. Our findings highlight the importance of controlling for the effects of anesthesia when detecting changes in hippocampal lactate levels in vivo and offer a novel protocol for enhanced cerebral lactate detection.

CNPY2 protects against ER stress and is expressed by corticostriatal neurons together with CTIP2 in a mouse model of Huntington's disease.

Canopy Homolog 2 (CNPY2) is an endoplasmic reticulum (ER) localized protein belonging to the CNPY gene family. We show here that CNPY2 is protective against ER stress induced by tunicamycin in neuronal cells. Overexpression of CNPY2 enhanced, while downregulation of CNPY2 using shRNA expression, reduced the viability of neuroblastoma cells after tunicamycin. Likewise, recombinant CNPY2 increased survival of cortical neurons in culture after ER stress. CNPY2 reduced the activating transcription factor 6 (ATF6) branch of ER stress and decreased the expression of CCAT/Enhancer-Binding Protein Homologous Protein (CHOP) involved in cell death. Immunostaining using mouse brain sections revealed that CNPY2 is expressed by cortical and striatal neurons and is co-expressed with the transcription factor, COUPTF-interacting protein 2 (CTIP2). In transgenic N171-82Q mice, as a model for Huntington's disease (HD), the number of CNPY2-immunopositive neurons was increased in the cortex together with CTIP2. In the striatum, however, the number of CNPY2 decreased at 19 weeks of age, representing a late-stage of pathology. Striatal cells in culture were shown to be more susceptible to ER stress after downregulation of CNPY2. These results demonstrate that CNPY2 is expressed by corticostriatal neurons involved in the regulation of movement. CNPY2 enhances neuronal survival by reducing ER stress and is a promising factor to consider in HD and possibly in other brain diseases.

Analysis of Brain Protein Stability Changes in a Mouse Model of Alzheimer's Disease.

The stability of proteins from rates of oxidation (SPROX), thermal proteome profiling (TPP), and limited proteolysis (LiP) techniques were used to profile the stability of ∼2500 proteins in hippocampus tissue cell lysates from 2- and 8-months-old wild-type (C57BL/6J; n = 7) and transgenic (5XFAD; n = 7) mice with five Alzheimer's disease (AD)-linked mutations. Approximately 200-500 protein hits with AD-related stability changes were detected by each technique at each age point. The hit overlap from technique to technique was low, and all of the techniques generated protein hits that were more numerous and largely different from those identified in protein expression level analyses, which were also performed here. The hit proteins identified by each technique were enriched in a number of the same pathways and biological processes, many with known connections to AD. The protein stability hits included 25 high-value conformation biomarkers with AD-related stability changes detected using at least 2 techniques at both age points. Also discovered were subunit- and age-specific AD-related stability changes in the proteasome, which had reduced function at both age points. The different folding stability profiles of the proteasome at the two age points are consistent with a different mechanism for proteasome dysfunction at the early and late stages of AD.

Single-cell RNA sequencing data locate ALDH1A2-mediated retinoic acid synthetic pathway to glomerular parietal epithelial cells.

Aldehyde dehydrogenase 1, family member A2, is a retinoic acid-synthesizing enzyme encoded by Aldh1a2 in mice and ALDH1A2 in humans. This enzyme is indispensable for kidney development, but its role in kidney physiology and pathophysiology remains to be fully defined. In this review, we mined single-cell and single-nucleus RNA sequencing databases of mouse and human kidneys and found that glomerular parietal epithelial cells (PECs) express a full set of genes encoding proteins needed for cellular vitamin A uptake, intracellular transport, and metabolism into retinoic acid. In particular, Aldh1a2/ALDH1A2 mRNAs are selectively enriched in mouse and human PECs. Aldh1a2 expression in PECs is greatly increased in a mouse model of anti-glomerular basement membrane glomerulonephritis and moderately induced in a mouse model of ischemia-reperfusion acute kidney injury. Aldh1a2 expression in PECs is substantially repressed in a chronic kidney disease mouse model combining diabetes, hypertension, and partial nephrectomy and is moderately repressed in mouse models of focal segmental glomerulosclerosis and diabetic nephropathy. Single-nucleus RNA sequencing data show that ALDH1A2 mRNA expression in PECs is diminished in patients with chronic kidney disease associated with diabetes, hypertension and polycystic kidney disease. In addition to data mining, we also performed Spearman's rank correlation coefficient analyses and identified gene transcripts correlated with Aldh1a2/ALDH1A2 transcripts in mouse PECs and PEC subtypes, and in human PECs of healthy subjects and patients with AKI or CKD. Furthermore, we conducted Gene Ontology pathway analyses and identified the biological pathways enriched among these Aldh1a2/ALDH1A2-correlated genes. Our data mining and analyses led us to hypothesize that ALDH1A2-mediated retinoic acid synthesis in PECs plays a yet-undefined role in the kidney and that its dysregulation mediates injury. Conditional, PEC-selective Aldh1a2 knockout, RNA silencing and transgenic mouse models will be useful tools to test this hypothesis. Clinical studies on genetics, epigenetics, expression and functions of ALDH1A2 and other genes needed for retinoic acid biosynthesis and signaling are also warranted.

Urolithin a Improves Motor Dysfunction Induced by Copper Exposure in SOD1G93A Transgenic Mice Via Activation of Mitophagy.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease pathologically characterized by selective degeneration of motor neurons resulting in a catastrophic loss of motor function. The present study aimed to investigate the effect of copper (Cu) exposure on progression of ALS and explore the therapeutic effect and mechanism of Urolithin A (UA) on ALS. 0.13 PPM copper chloride drinking water was administrated in SOD1G93A transgenic mice at 6weeks, UA at a dosage of 50mg/kg/day was given for 6weeks after a 7-week Cu exposure. Motor ability was assessed before terminal anesthesia. Muscle atrophy and fibrosis, motor neurons, astrocytes and microglia in the spinal cord were evaluated by H&E, Masson, Sirius Red, Nissl and Immunohistochemistry Staining. Proteomics analysis, Western blotting and ELISA were conducted to detect protein expression. Mitochondrial adenosine triphosphate (ATP) and malondialdehyde (MDA) levels were measured using an assay kit. Cu-exposure worsened motor function, promoted muscle fibrosis, loss of motor neurons, and astrocyte and microglial activation. It also induced abnormal changes in mitochondria-related biological processes, leading to a significant reduction in ATP levels and an increase in MDA levels. Upregulation of P62 and downregulation of Parkin, PINK1, and LAMP1 were revealed in SOD1G93A mice with Cu exposure. Administration of UA activated mitophagy, modulated mitochondria dysfunction, reduced neuroinflammation, and improved gastrocnemius muscle atrophy and motor dysfunction in SOD1G93A mice with Cu exposure. Mitophagy plays critical role in ALS exacerbated by Cu exposure. UA administration may be a promising treatment strategy for ALS.

Characterization of ACTN4 as a novel antiviral target against SARS-CoV-2

The various mutations in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pose a substantial challenge in mitigating the viral infectivity. The identification of novel host factors influencing SARS-CoV-2 replication holds potential for discovering new targets for broad-spectrum antiviral drugs that can combat future viral mutations. In this study, potential host factors regulated by SARS-CoV-2 infection were screened through different high-throughput sequencing techniques and further identified in cells. Subsequent analysis and experiments showed that the reduction of m6A modification level on ACTN4 (Alpha-actinin-4) mRNA leads to a decrease in mRNA stability and translation efficiency, ultimately inhibiting ACTN4 expression. In addition, ACTN4 was demonstrated to target nsp12 for binding and characterized as a competitor for SARS-CoV-2 RNA and the RNA-dependent RNA polymerase complex, thereby impeding viral replication. Furthermore, two ACTN4 agonists, YS-49 and demethyl-coclaurine, were found to dose-dependently inhibit SARS-CoV-2 infection in both Huh7 cells and K18-hACE2 transgenic mice. Collectively, this study unveils the pivotal role of ACTN4 in SARS-CoV-2 infection, offering novel insights into the intricate interplay between the virus and host cells, and reveals two potential candidates for future anti-SARS-CoV-2 drug development.

Targeting ferroptosis with the lipoxygenase inhibitor PTC-041 as a therapeutic strategy for the treatment of Parkinson's disease.

Parkinson's disease is the second most common neurodegenerative disorder, affecting nearly 10 million people worldwide. Ferroptosis, a recently identified form of regulated cell death characterized by 15-lipoxygenase-mediated hydroperoxidation of membrane lipids, has been implicated in neurodegenerative disorders including amyotrophic lateral sclerosis and Parkinson's disease. Pharmacological inhibition of 15 -lipoxygenase to prevent iron- and lipid peroxidation-associated ferroptotic cell death is a rational strategy for the treatment of Parkinson's disease. We report here the characterization of PTC-041 as an anti-ferroptotic reductive lipoxygenase inhibitor developed for the treatment of Parkinson's disease. In these studies, PTC-041 potently protects primary human Parkinson's disease patient-derived fibroblasts from lipid peroxidation and subsequent ferroptotic cell death and prevents ferroptosis-related neuronal loss and astrogliosis in primary rat neuronal cultures. Additionally, PTC-041 prevents ferroptotic-mediated α-synuclein protein aggregation and nitrosylation in vitro, suggesting a potential role for anti-ferroptotic lipoxygenase inhibitors in mitigating pathogenic aspects of synucleinopathies such as Parkinson's disease. We further found that PTC-041 protects against synucleinopathy in vivo, demonstrating that PTC-041 treatment of Line 61 transgenic mice protects against α-synuclein aggregation and phosphorylation as well as prevents associated neuronal and non-neuronal cell death. Finally, we show that. PTC-041 protects against 6-hydroxydopamine-induced motor deficits in a hemiparkinsonian rat model, further validating the potential therapeutic benefits of lipoxygenase inhibitors in the treatment of Parkinson's disease.

Afterload-induced Decreases in Fatty Acid Oxidation Develop Independently of Increased Glucose Utilization.

Metabolic substrate utilization in HFpEF (heart failure with preserved ejection fraction), the leading cause of heart failure worldwide, is pivotal to syndrome pathogenesis and yet remains ill defined. Under resting conditions, oxidation of free fatty acids (FFA) is the predominant energy source of the heart, supporting its unremitting contractile activity. In the context of disease-related stress, however, a shift toward greater reliance on glucose occurs. In the setting of obesity or diabetes, major contributors to HFpEF pathophysiology, the shift in metabolic substrate use toward glucose is impaired, sometimes attributed to the lower oxygen requirement of glucose oxidation versus fat metabolism. This notion, however, has never been tested conclusively. Furthermore, whereas oxygen demand increases in the setting of increased afterload, myocardial oxygen availability remains adequate for fatty acid oxidation (FAO). Therefore, a "preference" for glucose has been proposed. Pyruvate dehydrogenase complex (PDC) is the rate-limiting enzyme linking glycolysis to the TCA cycle. As PDK4 (PDC kinase 4) is up-regulated in HFpEF, we over-expressed PDK4 in cardiomyocytes, ensuring that PDC is phosphorylated and thereby inhibited. This leads to diminished use of pyruvate as energy substrate, mimicking the decline in glucose oxidation in HFpEF. Importantly, distinct from HFpEF-associated obesity, this model positioned us to abrogate the load-induced shift to glucose utilization in the absence of systemic high fat conditions. As expected, PDK4 transgenic mice manifested normal cardiac performance at baseline. However, they manifested a rapid and severe decline in contractile performance when challenged with modest increases in afterload triggered either by L-NAME or surgical transverse aortic constriction (TAC). This decline in function was not accompanied by an exacerbation of the myocardial hypertrophic growth response. Surprisingly, metabolic flux analysis revealed that, after TAC, fractional FAO decreased, even when glucose/pyruvate utilization was clamped at very low levels. Additionally, proteins involved in the transport and oxidation of FFA were paradoxically downregulated after TAC regardless of genotype. These data demonstrate that cardiomyocytes in a setting in which glucose utilization is robustly diminished and prevented from increasing do not compensate for the deficit in glucose utilization by up-regulating FFA use.

Proteoglycan 4 (Lubricin) and Regulation of Xanthine Oxidase in Synovial Macrophage as A Mechanism of Controlling Synovitis.

Background Synovial macrophages (SMs) are important effectors of joint health and disease. A novel Cx3CR1 + TREM2 + SM population expressing the tight junction protein claudin-5, was recently discovered in synovial lining. Ablation of these SMs was associated with onset of arthritis. Proteoglycan 4 (PRG4) is a mucinous glycoprotein that fulfills lubricating and homeostatic roles in the joint. The aim of this work is to study the role of PRG4 in modulating synovitis in the context of SM homeostasis and assess the contribution of xanthine oxidase (XO)-hypoxia inducible factor alpha (HIF-1a) axis to this regulation. Methods We used Prg4 FrtloxP/FrtloxP ; R26 FlpoER/+ , a novel transgenic mouse, where the Prg4 Frt allele normally expresses the PRG4 protein and was designed to flank the first two exons of Prg4 with a flippase recognition target and "LOXP" sites. Inducing flippase activity with tamoxifen (TAM) inactivates the Frt allele and thus creates a conditional knockout state. We studied anti-inflammatory SMs and XO by quantitative immunohistochemistry, isolated RNA and studied immune pathway activations by multiplexed assays and isolated SMs and studied PRG4 signaling dysfunction in relation to glycolytic switching due to pro-inflammatory activation. Prg4 inactivated mice were treated with oral febuxostat, a specific XO inhibitor, and quantification of Cx3CR1 + TREM2 + SMs, XO immunostaining and synovitis assessment were conducted. Results Prg4 inactivation induced Cx3CR1 + TREM2 + SM loss ( p < 0.001 ) and upregulated glycolysis and innate immune pathways in the synovium. In isolated SMs, Xdh ( p < 0.01 ) and Hif1a ( p < 0.05 ) were upregulated. Pro-inflammatory activation of SMs was evident by enhanced glycolytic flux and XO-generated reactive oxygen species (ROS). Febuxostat reduced glycolytic flux ( p < 0.001 ) and HIF-1a levels ( p < 0.0001 ) in SMs. Febuxostat also reduced systemic inflammation ( p < 0.001 ), synovial hyperplasia ( p < 0.001 ) and preserved Cx3CR1 + TREM2 + SMs ( p < 0.0001 ) in synovia of Prg4 inactivated mice. Conclusions PRG4 is a biologically significant modulator of synovial homeostasis via inhibition of XO expression and downstream HIF-1a activation. PRG4 signaling is anti-inflammatory and promotes synovial homeostasis in chronic synovitis, where direct XO inhibition is potentially therapeutic in chronic synovitis.

Retention of ES cell-derived 129S genome drives NLRP1 hypersensitivity and transcriptional deregulation in Nlrp3tm1Flv mice.

Immune response genes are highly polymorphic in humans and mice, with heterogeneity amongst loci driving strain-specific host defence responses. The inadvertent retention of polymorphic loci can introduce confounding phenotypes, leading to erroneous conclusions, and impeding scientific advancement. In this study, we employ a combination of RNAseq and variant calling analyses to identify a substantial region of 129S genome, including the highly polymorphic Nlrp1 locus, proximal to Nlrp3, in one of the most commonly used mouse models of NLRP3 deficiency (Nlrp3tm1Flv). We show that the presence of the Nlrp1129S locus leads to an increase in NLRP1B protein expression, and a sensitising of Nlrp3tm1Flv macrophages to NLRP1 inflammasome activation, independent of NLRP3 deficiency. Retention of 129S genome further leads to protein sequence differences and altered gene regulation across multiple cell types, including of the key tissue-resident macrophage marker, TIM4. Using alternative models of NLRP3 deficiency, including a previously undescribed conditional Nlrp3 allele enabling precise temporal and cell-type specific control over Nlrp3 deletion, we further show that NLRP3 contributes to Talabostat-driven IL-1β release. Our study also establishes a generic framework to identify functionally relevant SNPs and assess genomic contamination in transgenic mice using RNAseq data. This allows for unambiguous attribution of phenotypes to the target gene and advances the precision and reliability of research in the field of host defence responses.

Oxytocin shortens spreading depolarization-induced periorbital allodynia

BackgroundMigraine is among the most prevalent and burdensome neurological disorders in the United States based on disability-adjusted life years. Cortical spreading depolarization (SD) is the most likely electrophysiological cause of migraine aura and may be linked to trigeminal nociception. We previously demonstrated, using a minimally invasive optogenetic approach of SD induction (opto-SD), that opto-SD triggers acute periorbital mechanical allodynia that is reversed by 5HT1B/1D receptor agonists, supporting SD-induced activation of migraine-relevant trigeminal pain pathways in mice. Recent data highlight hypothalamic neural circuits in migraine, and SD may activate hypothalamic neurons. Furthermore, neuroanatomical, electrophysiological, and behavioral data suggest a homeostatic analgesic function of hypothalamic neuropeptide hormone, oxytocin. We, therefore, examined the role of hypothalamic paraventricular nucleus (PVN) and oxytocinergic (OXT) signaling in opto-SD-induced trigeminal pain behavior.MethodsWe induced a single opto-SD in adult male and female Thy1-ChR2-YFP transgenic mice and quantified fos immunolabeling in the PVN and supraoptic nucleus (SON) compared with sham controls. Oxytocin expression was also measured in fos-positive neurons in the PVN. Periorbital mechanical allodynia was tested after treatment with selective OXT receptor antagonist L-368,899 (5 to 25 mg/kg i.p.) or vehicle at 1, 2, and 4 h after opto-SD or sham stimulation using von Frey monofilaments.ResultsOpto-SD significantly increased the number of fos immunoreactive cells in the PVN and SON as compared to sham stimulation (p < 0.001, p = 0.018, respectively). A subpopulation of fos-positive neurons also stained positive for oxytocin. Opto-SD evoked periorbital mechanical allodynia 1 h after SD (p = 0.001 vs. sham), which recovered quickly within 2 h (p = 0.638). OXT receptor antagonist L-368,899 dose-dependently prolonged SD-induced periorbital allodynia (p < 0.001). L-368,899 did not affect mechanical thresholds in the absence of opto-SD.ConclusionsThese data support an SD-induced activation of PVN neurons and a role for endogenous OXT in alleviating acute SD-induced trigeminal allodynia by shortening its duration.