Mouse Model Research Articles

Developing Stapled Aptamers with a Constrained Conformation for Osteogenesis Imperfect Therapeutics.

Despite the extensive development of aptamers in basic research, only a limited number have successfully progressed to clinical trials. This limitation is primarily attributed to the inherent instability of aptamers' conformation, resulting in low affinity, poor serum stability, and inconsistent potency, posing a significant challenge to their stabilization. Herein, we established a feasible strategy to develop staple aptamers using the predicted binding conformations and titration cross-linking (TTC) method. Through this strategy, we successfully synthesized various stapled sclerostin aptamers with over 70% yield. Importantly, we demonstrated that stapled aptamers significantly enhanced their affinity (approximately 20-fold) and serum stability (negligible degradation within 32 h). Moreover, in an osteogenesis imperfecta mouse model (Col1a2+/G610C mice), the stapled aptamer (named c-0127OA) exhibited a potent antagonistic effect on sclerostin, leading to enhanced anabolic bone anabolic potential. Collectively, our established stapling strategy is effective in stabilizing aptamers' conformation, with c-0127OA emerging as a promising therapeutic candidate for osteogenesis imperfecta.

Multiple ASC-dependent inflammasomes drive differential pro-inflammatory cytokine production in a mouse model of tendinopathy.

Inflammasomes are multiprotein complexes that regulate the bioactive production of IL-1b and IL-18, being implicated in the inflammatory response of different diseases. The inflammasome formed by the cytosolic sensor NLRP3 is highly promiscuous, as it could be activated by different pathogen- and sterile-signals. However, few models have studied the implication of NLRP3 in tissue damage-induced inflammation, particularly the implication of NLRP3 in tendinopathies. Here we aimed to investigate the implication of NLRP3 in a mouse model of tendinopathy by collagenase degradation of the extracellular matrix in the Achilles' mice tendon. We found that NLRP3 was involved in the production of IL-1b and IL-6, but another ASC-dependent inflammasome was required to produce IL-18 during sterile tissue damage. Our study suggests that in the immune response to extracellular matrix degradation different inflammasomes, probably expressed in different cell compartments, were able to differentially control IL-1b and IL-18 production in vivo. These results suggest the potential use of therapies targeting ASC as beneficial in the treatment of tendinopathies.

Targeting a chemo-induced adaptive signaling circuit confers therapeutic vulnerabilities in pancreatic cancer

Advanced pancreatic ductal adenocarcinomas (PDACs) respond poorly to all therapies, including the first-line treatment, chemotherapy, the latest immunotherapies, and KRAS-targeting therapies. Despite an enormous effort to improve therapeutic efficacy in late-stage PDAC patients, effective treatment modalities remain an unmet medical challenge. To change the status quo, we explored the key signaling networks underlying the universally poor response of PDAC to therapy. Here, we report a previously unknown chemo-induced symbiotic signaling circuit that adaptively confers chemoresistance in patients and mice with advanced PDAC. By integrating single-cell transcriptomic data from PDAC mouse models and clinical pathological information from PDAC patients, we identified Yap1 in cancer cells and Cox2 in stromal fibroblasts as two key nodes in this signaling circuit. Co-targeting Yap1 in cancer cells and Cox2 in stroma sensitized PDAC to Gemcitabine treatment and dramatically prolonged survival of mice bearing late-stage PDAC, whereas simultaneously inhibiting Yap1 and Cox2 only in cancer cells was ineffective. Mechanistically, chemotherapy triggers non-canonical Yap1 activation by nemo-like kinase in 14-3-3ζ-overexpressing PDAC cells and increases secretion of CXCL2/5, which bind to CXCR2 on fibroblasts to induce Cox2 and PGE2 expression, which reciprocally facilitate PDAC cell survival. Finally, analyses of PDAC patient data revealed that patients who received Statins, which inhibit Yap1 signaling, and Cox2 inhibitors (including Aspirin) while receiving Gemcitabine displayed markedly prolonged survival compared to others. The robust anti-tumor efficacy of Statins and Aspirin, which co-target the chemo-induced adaptive circuit in the tumor cells and stroma, signifies a unique therapeutic strategy for PDAC.

TBAJ-587, a novel diarylquinoline, is active against Mycobacterium abscessus.

Nontuberculous mycobacteria (NTM) infections are extremely difficult to treat due to a natural resistance to many antimicrobials. TBAJ-587 is a novel diarylquinoline, which shows higher anti-tuberculosis activity, lower lipophilicity, and weaker inhibition of hERG channels than bedaquiline (BDQ). The susceptibilities of 11 NTM reference strains and 194 clinical Mycobacterium abscessus isolates to TBAJ-587 were determined by the broth microdilution assay. The activity of TBAJ-587 toward the growth of M. abscessus in macrophages was also evaluated. Minimum bactericidal concentration and time-kill kinetic assays were conducted to distinguish between the bactericidal and bacteriostatic activities of TBAJ-587. The synergy between TBAJ-587 and eight clinically important antibiotics was determined using a checkerboard assay. TBAJ-587 was highly effective against M. abscessus by targeting its F-ATP synthase c chain. The antimicrobial activities of TBAJ-587 and BDQ toward intracellular M. abscessus were comparable. The in vivo activities of TBAJ-587 and BDQ in an immunocompromised mouse model were also comparable. TBAJ-587 expressed bactericidal activity and was compatible with eight anti-NTM drugs commonly used in clinical practice; no antagonism was discovered. As such, TBAJ-587 represents a potential candidate for the treatment of NTM infections.

Multi-omics evaluation of clinical-grade human umbilical cord-derived mesenchymal stem cells in synergistic improvement of aging related disorders in a senescence-accelerated mouse model

BackgroundThe prevalence of age-related disorders, particularly in neurological and cardiovascular systems, is an increasing global health concern. Mesenchymal stem cell (MSC) therapy, particularly using human umbilical cord-derived MSCs (HUCMSCs), has shown promise in mitigating these disorders. This study investigates the effects of HUCMSCs on aging-related conditions in a senescence-accelerated mouse model (SAMP8), with a focus on DNA damage, gut microbiota alterations, and metabolic changes.MethodsSAMP8 mice were treated with clinical-grade HUCMSCs via intraperitoneal injections. Behavioral and physical assessments were conducted to evaluate cognitive and motor functions. The Single-Strand Break Mapping at Nucleotide Genome Level (SSiNGLe) method was employed to assess DNA single-strand breaks (SSBs) across the genome, with particular attention to exonic regions and transcription start sites. Gut microbiota composition was analyzed using 16S rRNA sequencing, and carboxyl metabolomic profiling was performed to identify changes in circulating metabolites.ResultsHUCMSC treatment significantly improved motor coordination and reduced anxiety in SAMP8 mice. SSiNGLe analysis revealed a notable reduction in DNA SSBs in MSC-treated mice, especially in critical genomic regions, suggesting that HUCMSCs may mitigate age-related DNA damage. The functional annotation of the DNA breaktome indicated a potential link between reduced DNA damage and altered metabolic pathways. Additionally, beneficial alterations in gut microbiota were observed, including an increase in short-chain fatty acid (SCFA)-producing bacteria, which correlated with improved metabolic profiles.ConclusionThe administration of HUCMSCs in SAMP8 mice not only reduces DNA damage but also induces favorable changes in gut microbiota and metabolism. The observed alterations in DNA break patterns, along with specific changes in microbiota and metabolic profiles, suggest that these could serve as potential biomarkers for evaluating the efficacy of HUCMSCs in treating age-related disorders. This highlights a promising avenue for the development of new therapeutic strategies that leverage these biomarkers, to enhance the effectiveness of HUCMSC-based treatments for aging-associated diseases.

Advancements in plant transformation: from traditional methods to cutting-edge techniques and emerging model species.

The ability to efficiently genetically modify plant species is crucial, driving the need for innovative technologies in plant biotechnology. Existing plant genetic transformation systems include Agrobacterium-mediated transformation, biolistics, protoplast-based methods, and nanoparticle techniques. Despite these diverse methods, many species exhibit resistance to transformation, limiting the applicability of most published methods to specific species or genotypes. Tissue culture remains a significant barrier for most species, although other barriers exist. These include the infection and regeneration stages in Agrobacterium, cell death and genomic instability in biolistics, the creation and regeneration of protoplasts for protoplast-based methods, and the difficulty of achieving stable transformation with nanoparticles. To develop species-independent transformation methods, it is essential to address these transformation bottlenecks. This review examines recent advancements in plant biotechnology, highlighting both new and existing techniques that have improved the success rates of plant transformations. Additionally, several newly emerged plant model systems that have benefited from these technological advancements are also discussed.

Signature of diabetic cardiomyopathy progression using high-fat diet and streptozotocin mouse model: from subclinical to clinical with three-hit mouse model

Abstract Background Diabetic cardiomyopathy (DbCM) is a pre-heart failure (pre-HF) condition that usually exhibits early diastolic dysfunction and evolving systolic dysfunction, along with left ventricular (LV) remodelling. Although DbCM shows distinct pathophysiology, the transition from the subclinical to the symptomatic stage is not straightforward and usually involves multifaceted processes which are not fully understood. Purpose To define the signature of DbCM progression in a novel mouse model using longitudinal echocardiography and multi-omics approaches. Methods Male mice (C57BL/6) were fed with high-fat diet (HFD) or control diet (CD) for 24 weeks, with single dose of streptozotocin (STZ) or vehicle injection at 8 weeks (n=10 each). Serial functional and metabolic parameters were measured prior to endpoint single nuclei RNA sequencing (snRNA-seq) and mass spectrometry-based proteomics analysis with comparison to cardiac remodelling to define detailed mechanisms underlying DbCM progression. Results HFD/STZ mice developed type 2 diabetes mellitus (T2DM) based on higher fasting blood glucose and HbA1C levels, insulin resistance and decreased beta-cell function (HOMA-IR and HOMA-beta, respectively) compared to controls. Progressive diastolic dysfunction was evident in HFD/STZ mice compared to CD mice based on enlarged LVPW;d from 12 weeks (P<0.05), reduced MV E/A ratio (P<0.01) and IVRT (P<0.05) from 16 weeks, and increased cardiac filling pressure (Left atrial (LA) area and LA volume) at 24 weeks, with preserved systolic function. This was paralleled by elevated collagen deposition (Picrosirius red), myocyte cross-sectional area and Col1a1 expression in HFD/STZ versus CD mice (all P<0.05). snRNA-seq analysis indicated preferential monocyte migration into diabetic hearts (P<0.01) whilst inflammatory pathways were activated across all cardiac cell types. Proteomics analysis revealed elevated expression of the established inflammation marker, plasma C-reactive protein (CRP), in HFD/STZ versus CD mice (P<0.05), which was correlated with worsening diastolic function (MV E/A ratio: r=-0.839, P<0.01) and LV hypertrophy (LVPW;d: r=0.861, P<0.01). Conclusion Our HFD/STZ mouse model offers a ‘three-hit’ approach which effectively captures key stages of clinical DbCM progression: 1) T2DM with insulin resistance, 2) progressive diastolic dysfunction with elevated chronic filling pressure and cardiac remodelling, and 3) systemic inflammation. This improved HFD/STZ mouse model is therefore appropriate to support a detailed study of mechanisms underlying DbCM progression and subsequent translation.

Deletion of the Uox gene generates a mouse model of hyperuricemia with cardiovascular complications

Abstract Background/introductions: Hyperuricemia is associated with hypertension, coronary atherosclerosis and heart failure. However, the causal relationship between uric acid (UA) and cardiovascular disease remains controversial. There has been lack of mouse model for spontaneous hyperuricemia with cardiovascular complications. Purpose We aimed to develop urate oxidase (Uox) deficient mice with hyperuricemia that can survive to adulthood. Methods Uox-knockout mouse model was generated on C57BL/6J background by deleting exon 2-4 of Uox using the CRISPR/Cas9 system. we evaluated the hyperuricemic phenotypes regarding magnitude of serum UA elevation, cardiometabolic abnormalities, and cardiovascular complications. Results The birth rate of homozygous Uox-knockout (Uox -/-) mice was 21.4%. The prototypic Uox -/-mice had 5.5-fold increased serum uric acid (1351.04±276.58 μmol/L) as compared to the wild type mice (P<0.0001)), but mostly died by four weeks. After allopurinol (3ug/g) intervention, they all survived more than eight weeks (median: 12.6 weeks, range:9.6 to 16.0 weeks). The serum UA was 612.55±146.98μmol/L (2.5 times higher than that in WT mice, P<0.0001) in the eight-week-old allopurinol-rescued Uox -/-mice, which also manifested multiple complications including hypertension (systolic blood pressure:155.25±9.48mmHg vs. 109.53±11.02mmHg, P<0.0001), left ventricular remodeling and systolic dysfunction (all echocardiographic functional parameters, P<0.001), aortic endothelial cell impairment (P<0.001 for proliferating cell nuclear antigen and ZO-1, P=0.027 for VE-cadherin), hepatic steatosis and elevated liver enzymes (all enzymes P<0.0001), as well as urate nephropathy, hyperglycemia (P=0.0146 for fasting glucose) and hypercholesteremia (P=0.0045 for total cholesterol). Conclusion The present Uox-/- mice developed spontaneous hyperuricemia complicated with cardiovascular disease and cardiometabolic disorders. This allopurinol-rescued Uox-/- mouse model could survive to adulthood, and may provide a novel tool to study urate biology and hyperuricemia associated early-onset disorders in human. Figure 1 Figure 2

A Novel Mouse Model for Cerebral Inflammatory Demyelination in X-Linked Adrenoleukodystrophy: Insights into Pathogenesis and Potential Therapeutic Targets.

X-linked adrenoleukodystrophy (ALD) is caused by mutations in ABCD1, a peroxisomal gene. More than half of males with an ABCD1 mutation develop inflammatory cerebral demyelination (cALD), but underlying mechanisms remain unknown and therapies are limited. We sought to develop and characterize a mouse model of cALD to facilitate study of disease mechanisms and therapy development. We used immunoassays and immunohistochemistry to assess novel (interleukin 18 [IL-18]) and established molecular markers in cerebrospinal fluid (CSF) and postmortem brain tissue from cALD patients. We generated a cALD phenotype in Abcd1-knockout mice using a 2-hit method that combines cuprizone and experimental autoimmune encephalomyelitis models. We then used magnetic resonance imaging (MRI) and immunohistochemistry to assess the fidelity of cALD molecular markers in the mice. Human and mouse cALD lesions shared histologic features of myelin phagocytosis, myelin loss, abundant microglial activation, T and B-cell infiltration, and astrogliosis. Compared to wild-type controls, Abcd1-knockout mice displayed more cerebral demyelination, blood-brain barrier disruption, and perivascular immune cell infiltration. This enhanced inflammatory response was associated with higher levels of fibrin deposition, oxidative stress, demyelination, and axonal injury. IL-18 immunoreactivity co-localized with perivascular monocytes/macrophages in both human and mouse brain tissue. In cALD patients, CSF IL-18 levels correlated with MRI lesion severity. Our results suggest loss of Abcd1 function in mice predisposes to more severe blood-brain barrier disruption, cerebral inflammation driven by the infiltration of peripheral immune cells, demyelination, and axonal damage, replicating human cALD features. This novel mouse model could shed light on cALD mechanisms and accelerate cALD therapy development. ANN NEUROL 2024.

Peripheral immune landscape of pediatric fulminant myocarditis revealed by single-cell sequencing

Abstract Fulminant myocarditis (FM) is one of the most feared diseases in children because of its fulminant nature and high mortality rate. However, the precise pathological immune subsets and molecular changes in FM are unknown. Here, we present the first comprehensive cellular and transcriptomic profiling of the peripheral blood mononuclear cells of children in FM acute and recovery phases using Single-cell RNA sequencing. 21 cell clusters are identified among 79542 cells. The proportion of T cells and NK cells increase, while myeloid cells and B cells reduce in acute phase, which were consistent with our flow cytometry data of 35 FM patients. Several unique cell types in peripheral blood are identified, including regulatory B cells, MAIT cells, adaptive NK cells and CD8+Tpex cells. The transcriptomic analysis exhibited elevated expression levels of chemokine receptor CXCR4 and S100A family genes almost in all cell types in FM acute phase, as well as MHC-II molecules in antigen-presenting cells. TCR and BCR exhibit remarkable amplification and obvious skewed usages of V genes in FM. Ligand receptor analysis show myeloid cells maintained active communication with other immune cells. Considering that CXCR4 may play an important role in myocarditis, we designed experiments to explore its function in mouse model. Vital myocarditis (VMC) mouse model was constructed using Coxsackie virus type3（CVB3）.We found that myocardial inflammation and myocardial injury of VMC mice were alleviated when treated with CXCR4 blocker. CXCR4 may be a potential therapeutic target for myocarditis. Our study will provide useful insights into key immune cell subsets and transcriptomic profiles implicated in pediatric fulminant myocarditis acute phase and recovery phase, thus providing several potential diagnostic and therapeutic targets for this disease.

Smooth muscle cell-specific deletion of S100A4 modifies smooth muscle cell fate and inflammation in murine atherosclerotic lesions

Abstract Background S100A4, a calcium-binding protein, is crucial in smooth muscle cell (SMC) phenotypic switch, yet its role in atherosclerotic plaque development and SMC plasticity remains unclear. Our previous experiments using an S100A4 neutralizing antibody approach in ApoE-/- atherosclerotic-prone mice showed reduced atherosclerotic burden but did not establish a direct link between the various S100A4-expressing cells and atherosclerosis. Methods/Results Herein, we show that aortic Oil RedO staining in ApoE-/-; S100A4-/- mice subjected to a 12-week high-cholesterol-diet (HCD) revealed reduced lesion areas compared to ApoE-/- mice (Figure 1, from 21.29% of the total aorta in ApoE-/-; S100A4+/+ mice to 13.27% in ApoE-/-; S100A4-/- mice), highlighting a pivotal role for S100A4 in atherosclerotic plaque development. We then used a lineage tracing ApoE-/- mouse model, in which we induced an SMC-specific deletion of S100A4 (SMC-S100A4Δ/Δ). After 12 weeks of HCD, SMC-S100A4Δ/Δ and control mice (SMC-S100A4wt/wt) were sacrificed, and aortas were processed for en face Oil Red O staining, immunohistochemistry, and single-cell RNA sequencing (scRNA-seq). SMC-specific deletion of S100A4 reduced the necrotic core area (from 29.75% of total plaque area in SMC-S100A4wt/wt to 18.23% in SMC-S100A4Δ/Δ mice) without affecting total atherosclerotic plaque size suggesting a more potent impact on plaque composition. ScRNA-seq analysis from SMC-S100A4Δ/Δ and SMC-S100A4wt/wt mice showed that the inflammatory macrophage-like SMC phenotype was highly suppressed in the plaque and associated with increased SMC repair phenotypes as well as a global reduction of myeloid inflammatory cells. SMCs also retained specific contractile SMC markers, namely Acta2 and Myh11 (fold change of 2.285 and 2.492, respectively) hinting towards a more stable fibrous cap. Immunofluorescence staining on aortic roots plaque (Figure 2) confirmed those results with an increase of SMCs (from 11.02% to 16.18%) as well as a-smooth muscle actin (a-SMA, Acta2)-positive SMCs (from 3.25% to 5.1%) in SMC-S100A4 Δ/Δ mice. Furthermore, the Gene Set Enrichment Analysis (GSEA) of scRNAseq data revealed that, in SMC-S100A4Δ/Δ mice, genes related to mitochondrial metabolism and oxidative respiration were highly downregulated in all SMC clusters. We investigated SMC mitochondrial fitness in vitro and showed that S100A4-/- SMCs have an increased basal oxygen consumption rate and an increased proton leak (fold change of 1.37 and 1.96 respectively) suggestive of differences in cellular metabolic adaptability. Conclusion Our research emphasizes the significant role of S100A4 in plaque development, demonstrating how SMC-derived S100A4 knockdown affects plaque evolution, reducing inflammation, and promoting stability likely through influencing SMC phenotypic switch through metabolic pathways.

Computational staining of CD3/CD20 positive lymphocytes in human tissues with experimental confirmation in a genetically engineered mouse model

IntroductionImmune dysregulation plays a major role in cancer progression. The quantification of lymphocytic spatial inflammation may enable spatial system biology, improve understanding of therapeutic resistance, and contribute to prognostic imaging biomarkers.MethodsIn this paper, we propose a knowledge-guided deep learning framework to measure the lymphocytic spatial architecture on human H&E tissue, where the fidelity of training labels is maximized through single-cell resolution image registration of H&E to IHC. We demonstrate that such an approach enables pixel-perfect ground-truth labeling of lymphocytes on H&E as measured by IHC. We then experimentally validate our technique in a genetically engineered, immune-compromised Rag2 mouse model, where Rag2 knockout mice lacking mature lymphocytes are used as a negative experimental control. Such experimental validation moves beyond the classical statistical testing of deep learning models and demonstrates feasibility of more rigorous validation strategies that integrate computational science and basic science.ResultsUsing our developed approach, we automatically annotated more than 111,000 human nuclei (45,611 CD3/CD20 positive lymphocytes) on H&E images to develop our model, which achieved an AUC of 0.78 and 0.71 on internal hold-out testing data and external testing on an independent dataset, respectively. As a measure of the global spatial architecture of the lymphocytic microenvironment, the average structural similarity between predicted lymphocytic density maps and ground truth lymphocytic density maps was 0.86 ± 0.06 on testing data. On experimental mouse model validation, we measured a lymphocytic density of 96.5 ± %1% in a Rag2+/- control mouse, compared to an average of 16.2 ± %5% in Rag2-/- immune knockout mice (p<0.0001, ANOVA-test).DiscussionThese results demonstrate that CD3/CD20 positive lymphocytes can be accurately detected and characterized on H&E by deep learning and generalized across species. Collectively, these data suggest that our understanding of complex biological systems may benefit from computationally-derived spatial analysis, as well as integration of computational science and basic science.

Targeting an altered sphingolipid profile with consecutive lipotoxicity as therapeutic approach to calcific aortic valve disease

Abstract Background Aortic stenosis due to calcific aortic valve disease (CAVD) is the most common valvular heart disease. In symptomatic patients, without repair the prognosis is poor. Treatment to date is based on surgery or catheter-based interventions. Pharmacological therapy options to prevent the progression of valve calcification are not available. In vascular smooth muscle cells, cellular accumulation of sphingolipids is associated with a proinflammatory response in the sense of lipotoxicity. Chronic inflammatory processes are indeed also essential for aortic valve calcification. Purpose With the subsequent goal of developing innovative treatment approaches for CAVD, we therefore aim to elucidate the unclear role of sphingolipids in the development of CAVD. Methods Human aortic valve and plasma samples of CAVD patients and controls (n=26) were analysed by liquid chromatography–mass spectrometry for lipidomics and proteomics. Human aortic valve interstitial cells (hVICs) were stimulated with ceramides. Calcification was detected by alizarin red staining. mRNA expression of bone-related proteins was determined by qPCR. NF-kB pathway was assessed by proteome profiler. Myriocin and GW4869 were applied to inhibit ceramide biosynthesis. PDTC and MCC950 were used to inhibit NF-kB Pathway and NLRP3 activation. ApoE-/- mice received a gain-of-function PCSK9 adeno-associated virus vector and fed high cholesterol diet for 14 weeks. Myriocin was applied orally over the treatment period to inhibit ceramide de novo synthesis in vivo. Murine echocardiography was used to measure transvalvular velocity and left ventricular function. Calcification degree of murine aortic valve was determined by histological staining. Results A significantly altered sphingolipid profile was observed in aortic valve tissue of CAVD patients (Fig. 1). Ceramide species e.g. Cer (17:1;2O/16:0) were increased. Verifying the biological relevance of these findings in vitro, C2-Cer (d18:1/2:0) enhanced hVIC calcification (Fig. 2). Accordingly, ALP activity and mRNA expression of osteogenic genes RUNX2, ALPL and MSX2 were increased. Furthermore, C2-Cer (d18:1/2:0) enhanced NF-kB p65 phosphorylation and NLRP3 activation, while treatment with both PDTC and MCC950 protected against C2-Cer (d18:1/2:0) induced calcification. Supporting the role of sphingolipid biosynthesis in hVIC calcification, Myriocin and GW4869 both reduced ox-LDL-induced VIC calcification which was reversed by C2-Cer(d18:1/2:0). Finally, Myriocin reduced the degree of calcification and transvalvular jet velocity of aortic valve in the PCSK9-AAV ApoE-/- mice model. Conclusion CAVD is accompanied by an accumulation of ceramides causing lipotoxicity in human aortic valve tissue. Pharmacological modulation of sphingolipid metabolism is an effective approach to prevent the development and progression of aortic valve calcification in vivo and should be considered as a future therapeutic strategy in CAVD patients.Volcano Plot of CAVD tissue lipidomicsC2 Ceramide enhances hVIC calcification

Water deprivation induces a systemic pro-catabolic state that differentially affects oxidative and glycolytic skeletal muscles in male mice.

Dehydration, characterized by the loss of total body water and/or electrolytes due to diseases or inadequate fluid intake, is prevalent globally but often underestimated. Its contribution to long-term chronic diseases and sarcopenia is recognized, yet the mechanisms involved in systemic and muscle protein metabolism during dehydration remain unclear. This study investigated metabolic adaptations in a 36-hour water deprivation (WD) model of mice. Male C57BL/6 mice underwent 36-h WD or pair-feeding at rest, with assessments of motor skills along with biochemical, and metabolic parameters. Dehydration was confirmed by hypernatremia, body mass loss, hyporexia, and increased activity of vasopressinergic and oxytocinergic neurons compared to controls. These results were associated with liver mass loss, decreased glycaemia, and increased cholesterolemia. Additionally, increased VO2 and a decreased respiratory exchange ratio indicated reduced carbohydrate consumption and potentially increased protein use during dehydration. Thus, skeletal muscle protein metabolism was evaluated due to its high protein content. In the oxidative muscles of the WD group, total and proteasomal proteolysis increased, which was associated with decreased Akt-mediated intracellular signaling. Interestingly, there was an increase in fiber cross-sectional area, likely due to higher muscle water content caused by increased intracellular osmolality induced by protein catabolism products. Conversely, no changes were observed in protein turnover or water content in glycolytic muscles. These findings suggest that short-term WD imposes a pro-catabolic state, depleting protein content in skeletal muscle. However, skeletal muscle may respond differently to dehydration based on its phenotype and might adapt for a limited time.

Effect of sacubitril/valsartan and dapagliflozin on athletic performance; can the popular cardiac medications of recent years be used as doping agents?

Abstract Background/Introduction Recent guidelines have highlighted the positive impacts of sacubitril/valsartan and dapagliflozin on heart failure management [1]. Given their potential misuse as doping agents in professional sports, this study evaluates their effects on athletic performance. Purpose To investigate the effects of sacubitril/valsartan and dapagliflozin on athletic performance and cardiac functions in a rodent model. Methods The study had a randomized double-blind design. 24 Sprague-Dawley male rats aged 4 months, divided into control, sacubitril/valsartan, and dapagliflozin groups. The rats were weighed at the start of the experiment. The medications (dapagliflozin 1,5 mg/kg/1 ml/once a day, sacubitril/valsartan 60 mg/kg/1 ml/once a day to their respective groups, and normal saline for control group) were administered via gastric gavage for 30 days. The rats were weighed, examined with transthoracic echocardiography and put on rotarod at the start of the experiment, and on 15th and 30th days. The rats were put on forced swimming tests for 20 days. Exhaustion, loss of coordinated movements and failure to surface for 3 seconds after submersion in the water were defined as indications for ending the test as per the guidelines regarding rat exercise testing [2]. M-mode and Doppler measurements, forced swimming test durations, rotarod durations and weight were recorded on 0th, 15th and 30th days. Results Initial performance metrics, including echocardiography, weight, and rotarod tests, showed no significant differences among the groups at baseline. The distributions in data were non-normal. Over the course of the study, median swimming times significantly differed from the 9th session, with dapagliflozin-treated rats exhibiting a substantial increase in endurance. Specifically, dapagliflozin group's swimming times increased to a median of 3580 seconds by the 20th session, compared to 2382 seconds in the control group and 2591 seconds in the sacubitril/valsartan group, indicating a pronounced improvement in exercise capacity (P<0.0001)(Figure-1). Echocardiographic assessments revealed enhanced cardiac output and ejection fraction, particularly in the sacubitril/valsartan group, suggesting increased cardiac efficiency and potential athletic performance enhancement. Conclusion(s) The study demonstrates a significant improvement in athletic performance with dapagliflozin compared to sacubitril/valsartan. These findings suggest a potential for misuse in sports doping, emphasizing the need for stringent regulation and monitoring within competitive athletics.Figure-1

Comparative effects of ranolazine and trimetazidine on cardiac structure and exercise capacity in a healthy rat model: a new doping agent?

Abstract Background/Introduction Anti-anginal drugs that have been shown to improve myocardial energy use include ranolazine and trimetazidine [1]. An inquiry is warranted into their ability to impact cardiac functions and exercise capacity. Purpose This study aims to evaluate the effects of ranolazine; and trimetazidine as a positive control group on cardiac structure and exercise capacity in a rodent model in comparison with the control group. Methods In a randomized, controlled trial, 24 Sprague-Dawley rats were divided into three groups: control, ranolazine, and trimetazidine. Rats were given daily doses of ranolazine (50 mg/kg/1 ml) [2], trimetazidine (10 mg/kg/1 ml) [3], or saline (control) via gastric gavage for 30 days. At the beginning of the trial, as well as on the 15th and 30th days, the rats were weighed, placed on rotarod, and assessed using transthoracic echocardiography (Figure 1). The rats underwent 21 days of forced swimming testing. According to the guidelines for rat exercise testing [4], signs of exhaustion, lack of coordinated movements, and failure to surface for three seconds following submersion in the water were designated as grounds for terminating the test. Weight, rotarod durations, M-mode and Doppler measurements, and forced swimming test durations were recorded on the 0th, 15th, and 30th days. Results No discernible differences were found between the groups in the initial evaluations. By using echocardiography, the left ventricular masses expanded in all three, indicating the emergence of an athlete's heart. In comparison to the control group, the ranolazine and trimetazidine groups showed considerable increases in their ability to exercise. In particular, the swimming times of the trimetazidine group and the ranolazine group improved to a mean of 1889 seconds by the 21st session, 1700 seconds in the trimetazidine group, and 1548 seconds in the control group (Figure 2), respectively, indicating enhanced cardiac performance. Conclusion(s) Ranolazine exhibits significant potential to enhance exercise capacity and cardiac efficiency in rats, surpassing the effects observed with trimetazidine. Trimetazidine is already registered as a doping agent in WADA [5]. These findings highlight the potential use of ranolazine as a performance enhancing agent in healthy subjects for a malicious purpose of creating unfair advantages in professional sports. Further studies in human subjects are needed.Figure 1Figure 2

Mitochondrial Oxidative Stress and Cardiac Dysfunction in TERT Knockout Mice

Abstract Background Heart failure (HF) is a major cause of hospitalization in the elderly, with its incidence increasing due to aging and associated risk factors like hypertension, diabetes, and myocardial fibrosis. Aging-related myocardial fibrosis, characterized by alterations in the extracellular matrix and myocardial structure, impairs cardiac function. Mitochondrial oxidative stress plays a pivotal role in cardiac electrical and structural remodeling, necessitating a deeper understanding of its involvement in aging-related heart failure. Purpose The purpose of this study is to investigate the mechanisms of aging-related ventricular electrical and structural remodeling by constructing an aging mouse model. This research aims to provide potential therapeutic targets for heart failure associated with aging. Methods We developed a third-generation homozygous telomerase reverse transcriptase (TERT) knockout mouse model. Comparing third-generation homozygous TERT knockout mice (F3 group) with age-matched wild-type males (WT group). The study encompassed blood pressure measurement, electrocardiographic analysis, echocardiography, ELISA for cardiac biomarkers, ventricular tissue electrophysiology, fibrosis assessment through staining, transcriptomic profiling via RNA-seq, and electron microscopy of ventricular mitochondria. Results Compared to the WT group, the F3 group demonstrated increased P53 and P16 protein expression. Decreased LVEF and FS, along with increased interventricular septum thickness, left ventricular diameter, and left ventricular volume. Elevated serum NT-pro-BNP and troponin I (cTnI) levels, with prolonged QRS duration. Decreased left and right ventricular conduction velocity, accompanied by increased conduction dispersion. Notable elevation in COLI, TGFβ, and α-SMA gene transcription and protein expression in ventricular tissue. Significant differences in mitochondrial oxidative stress signal pathways via RNA-seq analysis. Elevated serum MDA levels and decreased SOD levels, with up-regulated Mn-SOD gene transcription and protein expression, and down-regulated MFN2 and Drp1 gene transcription and protein expression in ventricular tissue. Electron microscopy revealed mitochondrial abnormalities such as loose arrangement, decreased number, swelling, vacuolation, and myofilament disintegration or breakage in the F3 group. Conclusion Third-generation TERT-/- senescent mice exhibit notable cardiac impairments, including electrical remodeling, structural changes, and mitochondrial dysfunction. These findings suggest a potential link between mitochondrial oxidative stress and aging-related heart failure, indicating novel therapeutic opportunities targeting mitochondrial dysfunction for managing such conditions.

Cancer ameliorates cardiac dysfunction and suppresses fibrosis in a mouse model for Duchenne muscular dystrophy

Abstract The interplay between heart failure and cancer represents a double-edged sword. Whereas cardiac remodeling promotes cancer progression, tumor growth suppresses cardiac hypertrophy and reduces fibrosis deposition. Whether these two opposing interactions are connected awaits to be determined. In addition, it is not known whether cancer affects solely the heart, or if other organs are affected as well. To explore the dual interaction between heart failure and cancer, we studied the human genetic disease Duchenne Muscular Dystrophy (DMD) using the MDX mouse model. We analyzed fibrosis and cardiac function as well as molecular parameters by multiple methods in the heart, diaphragm, lungs, skeletal muscles, and tumors derived from MDX and control mice. Surprisingly, cardiac dysfunction in MDX mice failed to promote murine cancer cell growth. In contrast, tumor-bearing MDX mice displayed reduced fibrosis in the heart , skeletal and diaphragm muscles, resulting in improved cardiac function. The latter is at least partially mediated via M2 macrophage recruitment to the heart and diaphragm muscles. Remarkably, an analysis of of cytokines in the blood of tumor-bearing and non-tumor-bearing MDX mice initially revealed several potential factors. These factors hold promise in significantly reducing fibrosis within our model. Administering these factors simultaneously to MDX mice led to decreased fibrosis in the heart, diaphragm, and skeletal muscles, along with an improvement in cardiac function. Collectively, our data support the notion that the effect of heart failure on tumor promotion is independent of the improved cardiac function in tumor-bearing mice. Reduced fibrosis in tumor-bearing MDX mice stems from the suppression of new fibrosis synthesis and the removal of existing fibrosis. These findings offer potential therapeutic strategies for DMD patients, fibrotic diseases, and cardiac dysfunction.Tumor growth suppresses fibrosisGraphical representation

Oral low-dose rapamycin treatment prevents aortic aneurysms in marfan mice

Abstract Background/Introduction Marfan syndrome (MFS) is a hereditary connective tissue disorder caused by fibrillin-1 (FBN1) gene mutations. Life-threatening complications are cardiovascular, e.g. thoracic aortic aneurysms and dissections. The pathophysiological cause is the increased release of transforming growth factor β-1 (TGF-β1) from the FBN1-deficient extracellular matrix (ECM) and structural disintegrity. Overactivation of the mechanistic target of rapamycin (mTOR) pathway has been demonstrated in the murine mgR/mgR model of MFS. Short-term administration of rapamycin significantly reduced aortic aneurysm formation and increased the life span in these mice. Purpose To assess the effect of an early continuous oral low-dose rapamycin treatment on the aortic aneurysm formation in the FBN1 hypomorphic mgR/mgR mouse model. Methods Male and female 3-4 week-old mgR/mgR mice were orally administered vehicle or rapamycin through diet (8mg/kg/KG) and sacrificed after 11 weeks. Rapamycin concentration was measured by liquid chromatography-mass spectrometry in whole blood. Aortic diameter was studied using echocardiography. Histopathological and immunofluorescence analyses were performed using aortic tissue sections and techniques. Results Blood rapamycin concentration following oral administration remained below detection level. Rapamycin normalized the aortic wall thickness and the diameter in female mgR/mgR mice to levels of the littermate control mice but not in male mgR/mgR mice. The circumferentially distributed elastin fibres remained significantly intact in sections of the ascending aorta of female mice. Echocardiography revealed that rapamycin-treated female mice stayed below a cut-off value for aortic aneurysms of 2 mm inner aortic diameter eight weeks after starting therapy. In contrast, vehicle-treated female animals already exceeded this value after five weeks. In female but not in male mice, the abundance of the mTOR downstream target phosphorylated ribosomal protein S6 was effectively suppressed by low-dose rapamycin up to levels detected in control animals. At the same time, extracellular matrix proteins like the proteoglycan aggrecan (ACAN) and the related chondroitin sulfate were significantly decreased in female mice. The abundance of ADAMTS5 transglutaminase-2 and xylosyltransferase-1, key enzymes involved in the turnover of proteoglycans and biosynthesis of glycosaminoglycan chains, was improved by the rapamycin treatment in female mice. No decrease in mTOR activity could be detected in male mgR/mgR animals. Here, the ACAN and chondroitin sulphate levels also remained at the level of the vehicle-treated animals. Conclusions Chronic low-dose rapamycin treatment reduced aneurysm formation only in female mgR/mgR mice, since the dose was too low for male mgR/mgR mice, by affecting the composition and organization of key ECM components essential for maintaining aortic homeostasis and mechanical properties.

Global deficiency in the inflammatory chemokine receptors 1,2,3 and 5 prevents vascular dysfunction in angiotensin II-induced hypertension and selectively modulates aortic myeloid cell phenotype

Abstract Background Leukocyte migration to the vasculature and the heart plays a critical role in hypertensive immune responses and is a carefully orchestrated process, regulated by the interactions of inflammatory chemokines with their receptors, notably CCR1, CCR2, CCR3, and CCR5 (collectively termed inflammatory chemokine receptors (iCCRs)). However, the inflammatory chemokine/receptor system is characterised by redundancy, ligand sharing and overlapping expression patterns. Consequently, our understanding of the specific and combinatory roles of chemokine receptors in cardiovascular inflammation remains incomplete, thus hindering the development of targeted therapies. To address this challenge, we have utilised two novel mouse models: iREP mice, carrying fluorescent reporters of inflammatory chemokine receptor expression, and TACKO mice, in which the entire iCcr locus containing Ccr1, Ccr2, Ccr3, and Ccr5 has been deleted. Purpose To evaluate the expression pattern of iCCRs in experimental hypertension and understand how the global deletion of iCCRs impacts disease progression. Methods We induced hypertension in mice by subcutaneously implanting osmotic minipumps administering angiotensin II (Ang II) for a duration of 14 days. Single-cell RNA sequencing was utilised for investigating iCCR expression in aortas during hypertension. Additionally, we employed flow cytometry and confocal microscopy to track iCCR expression and localization in aortas and hearts obtained from iREP mice. TACKO mice were utilised to assess the effect of global iCCr deficiency on hypertensive phenotypes. Blood pressure was measured via telemetry and vascular function was assessed using myography. Vascular and heart remodelling were evaluated through histology. Molecular mechanisms were analysed using Western Blotting and RT-qPCR, while immune cell changes in the aorta were evaluated through cytometry of time-of-flight (CyTOF). Results Ang II infusion induced higher iCCRs expression levels in both the aorta and the heart in comparison with sham treatment, particularly in fibrotic areas. After Ang II-treatment, global deletion of iCCRs in TACKO mice resulted in the prevention of endothelial dysfunction (n=5/group, P<0.05) and perivascular fibrosis (n=6-9, P<0.01), and a reduction in cardiomyocyte size (n=12-16, P<0.01) compared to wild type mice. However, no significant improvements were observed in other hypertensive phenotypes, including blood pressure, heart fibrosis, vascular NO synthase, and oxidative stress. CyTOF analysis revealed reductions in inflammatory monocytes and conventional type 2 dendritic cells in TACKO aorta, accompanied by a phenotypic switch in macrophages towards a less inflammatory phenotype. Conclusion Deficiency in iCCRs confers protective effects against vascular dysfunction in experimental hypertension, primarily by selectively reducing inflammatory myeloid cell homing to the aorta.