Biology subjects

Ferreira, L.

Publications and source records attributed to Ferreira, L..

At least 19 recordsLinked to original sources

bioRxiv2026

15-deoxy-Δ12,14-prostaglandin J2 limits Salmonella infection through regulation of host TLR4 signaling and inflammasome activation

Enteric infections caused by Salmonella enterica remain a major global health concern and are increasingly associated with antimicrobial resistance. Therefore, new strategies to combat this important pathogen are needed. The interactions between S. enterica and the human host have been the subject of intense investigation over the last several decades, yet new findings continue to emerge. We previously showed that 15-deoxy-{Delta}12,14-prostaglandin J2 (15d-PGJ2) reduces Salmonella colonization of macrophages, but the mechanisms underlying this protective effect were still unknown. Here, we demonstrate that 15d-PGJ2 limits Salmonella infection by suppressing TLR4 signaling and inflammasome activation. Treatment with 15d-PGJ2 reduced TLR4 expression, NF-{kappa}B activation, iNOS, COX-2, nitric oxide production, IL-1{beta} release, and inflammasome-related targets, including NLRP3 and caspase-1 activity, while only partially reversing macrophage polarization. Combined treatment with the TLR4 antagonist TAK-242 further reduced bacterial colonization of and IL-1{beta} release by macrophages, supporting the involvement of TLR4 signaling in the effects of 15d-PGJ2. During mouse infections, 15d-PGJ2 reduced bacterial burdens in a tissue-dependent manner. Together, these findings demonstrate that 15d-PGJ2 limits Salmonella infection through selective modulation of TLR4 signaling and inflammasome activation.

microbiology↗

bioRxiv2026

INHIBITION OF LIGAND-DEPENDENT BMP SIGNALING BLUNTS MELANOMA GROWTH

Treatments for advanced melanoma have markedly improved, but a significant proportion of patients still receive little to no survival benefit with standard-of-care therapies due to resistance and relapse1-5. The discovery and development of novel targets and therapies are needed to continue to improve patient outcomes in advanced melanoma. The identification of ligand-dependent BMP signaling that inhibits differentiation and promotes survival of melanoma cells suggests it is a potential therapeutic target that could complement current therapies6. Expression of the BMP ligand GDF6 (a.k.a BMP13) is responsible for this activity, and its expression is correlated with poor outcomes for melanoma patients. Here, we describe a novel monoclonal antibody targeting GDF6 that causes melanoma cell differentiation and death and blunts tumor growth in vivo. Together, these results indicate BMP-directed therapy has significant potential as a novel therapy for patients with advanced melanoma.

Cancer Biology↗

bioRxiv2026

Distinct afferent signatures onto anterior and posterior VMHvl subdomains and their progesterone receptor-expressing neurons

Female sexual behavior is fundamentally coupled to reproductive state, requiring the dynamic and coordinated regulation of sexual receptivity and rejection across the estrous cycle. In mice, these opposing behaviors are controlled by distinct neuronal subpopulations within the anteroposterior subdomains of the ventrolateral ventromedial hypothalamus (VMHvl): the posterior VMHvl (pVMHvl) promotes sexual receptivity, whereas the anterior VMHvl (aVMHvl) drives sexual rejection. Although progesterone receptor-expressing (PR) neurons in both subregions are essential for these behaviors, the circuit mechanisms underlying this anteroposterior functional segregation remain poorly understood. Here, we investigated whether anterior and posterior VMHvl subdomains receive distinct afferent inputs that could support their divergent roles, and whether these inputs specifically target PR neurons. By combining retrograde tracing with whole-brain, machine learning-assisted quantification, we first mapped the afferent connectivity of the aVMHvl and pVMHvl. We found that while the two subdomains share the majority of their inputs, they also receive distinct and biased projections. The aVMHvl preferentially receives inputs from the anterior hypothalamic nucleus, paraventricular and peripeduncular thalamic nuclei, and the parabrachial nucleus, while the pVMHvl is preferentially innervated by the preoptic area, dorsal and ventral premammillary nuclei and anteroventral periventricular nucleus. To determine whether the identified afferents directly synapse onto the PR neurons, we performed monosynaptic rabies tracing from anterior and posterior VMHvl PR neurons. These experiments revealed that most anterior- and posterior-biased projections directly targeted PR VMHvl neurons. In addition, projections from the paraventricular thalamus, periaqueductal gray, and several pontine nuclei preferentially innervated aVMHvlPR neurons, whereas inputs from the mammillary nuclei mostly targeted pVMHvlPR neurons. Together, our results reveal distinct afferent architectures onto anterior and posterior PR VMHvl neurons, providing a circuit-level framework for understanding how hormonal state flexibly biases female sexual behavior toward receptivity or rejection.

neuroscience↗

bioRxiv2026

Dual Ligand Cooperation at the Plasma Membrane Drives Transport of Engineered Small Extracellular Vesicles Across Brain Endothelial Cells

The natural delivery properties of small extracellular vesicles (sEVs) can be harnessed and enhanced through engineering to create a new class of biotherapeutics, particularly for central nervous system (CNS) disorders. While evidence supports the ability of sEVs to cross biological barriers and deliver functional cargo to target cells, a limited understanding of their uptake and transport across the brain hinders their translational potential. In this study, we investigated either native and engineered sEVs, developed by us, using a novel modular engineering platform that employs a dual-targeting strategy to facilitate uptake and transport through human brain endothelial cells (BECs). By utilizing super-resolution microscopy, we provided direct insights into the mechanisms of docking, intracellular sorting, and transport of engineered sEVs. The engineered sEVs formulation demonstrated significantly enhanced uptake, intracellular trafficking across BECs, and the ability to bypass degradative pathways. In vivo, the engineered sEVs exhibited preferential accumulation in the brain choroid plexus, a structure located within the lateral and fourth ventricles, thereby effectively targeting the blood-cerebrospinal fluid (CSF) barrier. These findings highlight the potential of combining advanced targeting strategies with high-resolution imaging to study sEV interactions with the brain biological barriers and develop more effective CNS therapies.

bioengineering↗

bioRxiv2026

A room-temperature ⁸⁹Zr⁴⁺ radiolabelling strategy for small extracellular vesicles with enhanced plasma stability for PET Imaging

Both for diagnostic purposes and regenerative medicine, it is essential to develop advanced imaging platforms capable of tracking the biodistribution of small extracellular vesicles (sEVs), as current methods are limited by inadequate resolution and sensitivity. In this study, we introduce a novel labeling strategy utilizing the radioisotope zirconium-89 (89Zr), which boasts a half-life of 78.4 h and is cost-effective to produce. To achieve this, we designed a new chelator tailored for 89Zr4+ that offers enhanced stability compared to the conventional deferoxamine (DFO). This chelator forms a robust complex with 89Zr4+ at room temperature, suitable for sEV labeling for PET imaging applications. The radiolabeling process involved a two-step procedure: first, conjugation of the chelator to the sEVs, and second, radiolabeling with 89Zr4+. The resulting sEV-L1-Zr demonstrated a radiochemical yield of approximately 60% and maintained around 80% stability in plasma over seven days. Importantly, our modifications did not alter the morphology, surface protein composition, internal RNA content, or bioactivity of the sEVs. We successfully visualized sEVs at very low doses in the mouse heart following intravenous injection of sEV-L1-Zr. Additionally, ex vivo experiments using a Langendorff rat heart perfusion model confirmed targeted accumulation of the vesicles in cardiomyocytes as compared to other cells in the heart compartment. This approach provides a promising platform for sensitive and stable in vivo tracking of sEVs, advancing their application in both diagnostic imaging and regenerative therapies.

bioengineering↗

bioRxiv2026

Neural substrates of female sexual rejection: hypothalamic pathways to the periaqueductal gray

Selecting an appropriate behavioral response according to ones internal state is essential for well-being. Across the reproductive cycle, fluctuating levels of sex hormones align female behavior with reproductive capacity by modulating neuronal circuits that express hormone receptors. Sex hormone receptor-expressing neurons present along the anterior-posterior axis of the ventrolateral region of the ventromedial hypothalamus (VMHvl) are key regulators of female sexual behavior. While posterior progesterone receptor-expressing neurons of the VMHvl (pVMHvlPR+) are fundamental for female sexual receptivity during the receptive phase of the reproductive cycle, we have recently shown that anterior VMHvlPR+ (aVMHvlPR+) neurons are involved in rejection behavior when non-receptive. Here, we mapped the connectional architecture of aVMHvlPR+ neurons using viral tracing approaches. As expected, these neurons strongly project to several hypothalamic areas. Furthermore, consistent with previous reports, we show that aVMHvlPR+ neurons robustly project to several columns of the periaqueductal gray (PAG) along its anterior-posterior axis. Artificial activation of aVMHvlPR+ somas selectively recruits the dorsomedial PAG (dmPAG). Optogenetic activation of aVMHvlPR+ axons in the dmPAG partially recapitulates the rejection phenotype observed upon activation of aVMHvlPR+ somas, increasing the rate of rejections in receptive females. These findings reveal a putative pathway regulating female rejection behavior within a more complex circuit, ensuring that mating does not occur during non fertile periods.

neuroscience↗

bioRxiv2025

Enterocloster citroniae and related gut microbiome species modulate Vibrio cholerae biofilm formation through the production of bioactive small molecules

Cholera is a diarrheal disease that affects millions of people globally. Although the causative agent, Vibrio cholerae, has been extensively studied in isolation, investigation of its interactions with the gut microbiota started relatively recently. We and others previously showed that microbiota-derived metabolites significantly influence V. cholerae behavior. By investigating how an organic extract of human feces affects V. cholerae gene expression, we showed that gut metabolites strongly suppress swimming motility, a trait important for host colonization. Interestingly, extracts of pure cultures of a gut commensal, Enterocloster citroniae, recapitulated this inhibition. Here, we present a comprehensive examination of the effect of small molecules produced by E. citroniae and related species on V. cholerae behavior. We show that E. citroniae small molecules inhibit motility by various V. cholerae strains, and that several phylogenetically related species produce this activity, although the magnitude of the effect varies between strains. Using biofilm formation assays in static and flow conditions, we show that V. cholerae strongly induces biofilm formation in response to E. citroniae metabolites. Transcriptome and reporter analyses showed that several genes involved in synthesis of an extracellular polysaccharide are induced by E. citroniae metabolites. Lastly, we show that V. cholerae interactions with host cells are also modulated by this commensal. These findings advance our understanding of microbiome-pathogen interactions and how commensal bacteria influence V. cholerae virulence through the production of small molecules. In the future, this knowledge may be used to design novel microbiome-based therapeutic approaches to combat cholera and other infections. ImportanceThe human gut is home to a dense and rich community of microbes termed microbiota. This community has critical functions for host health, including protection against enteric pathogens. Despite this important role, we have only recently scratched the surface of the interactions that occur between members of the microbiota and pathogenic invaders. Cholerae is a disease that still causes significant morbidity and mortality worldwide. Studying how the causative agent, Vibrio cholerae, interacts with the microbiota will have implications not only for our understanding of this important microbial community, but may also lead to the development of new therapeutic strategies against cholera and potentially other infectious diseases.

microbiology↗

bioRxiv2025

Parkinson's disease risk factors are expressed at brain barriers.

Parkinsons disease (PD) is characterized by the selective loss of dopaminergic neurons in the substantia nigra pars compacta, but whether its etiology is cell autonomous remains unclear. Increasing evidence implicates the blood-central nervous system (CNS) barriers in disease development, highlighting the importance of identifying genetic risk factors linked to cells forming the cerebrovasculature to advance this emerging area of research. The objective of this study is to identify PD genetic risk factors associated with blood-brain (BBB) and blood-cerebrospinal fluid (BCSFB) barriers, and to validate protein localization in human tissue and experimental models. To do so, we integrated genome-wide association studies and single nuclei RNA-sequencing datasets from the human postmortem substantia nigra (SN), midbrain, or cortical samples from control and PD donors. An in-depth bioinformatics analysis identified genes enriched in cell types that form the multicellular architecture of brain barriers, including CAVIN2, ANXA1, ANO2, and LRP1B. We further validated whether corresponding proteins were present in cell types associated with the blood-CNS barriers in human and mouse post-mortem tissues, as well as in iPSC-differentiated cells and choroid plexus organoids. Results showed that quantifying the proportion of endothelial cells expressing PD-related genes was under-evaluated at the transcript level compared to immunofluorescence analyses. In addition, we observed that CAVIN2 and ANXA1 proteins were more abundant at the vasculature of the substantia nigra vs. cortex, and CAVIN2 protein levels were reduced in PD vs. control human postmortem tissues. In contrast, the investigation of mouse postmortem samples demonstrated that the CAVIN2 protein is only present in a subset of mouse blood vessels, compared to nearly all vessels in human tissue. Similarly, mouse ANXA1 protein localizes to dopaminergic neurons of the substantia nigra and not at the vasculature, as seen in human tissue. The primary outcome of this study is the identification of PD-relevant risk genes specifically expressed at brain barriers and enriched in PD-relevant brain regions. The secondary outcome is the demonstration of poor transcript-protein correlation in - at least - a subset of PD risk factors, and a low interspecies conservation of protein localization for the selected candidates. In conclusion, the BBB and BCSFB may represent understudied contributors to PD, endothelial-specific proteins appear differentially regulated compared to transcripts, and experimental models require comprehensive validation to ensure relevance to the human condition.

neuroscience↗

bioRxiv2025

Polychaete capture by native jellyfish and invasive ctenophore reveals a novel benthic pelagic trophic link

Shallow coastal and estuarine habitats are among the most productive ecosystems, sustained by dynamic benthic-pelagic coupling. While traditionally described through detrital fluxes, living-mediated trophic interactions remain underexplored. Here we present the first field evidence that benthic nereidid polychaetes are preyed upon by gelatinous zooplankton; the native scyphomedusae Aurelia aurita and the invasive ctenophore Mnemiopsis leidyi. These events occurred most frequently in summer, particularly in the inner reaches of a Danish fjord, and were more often associated with A. aurita than M. leidyi. Stable isotope analyses revealed seasonal and species-specific patterns: in summer, polychaetes shared similar isotopic signatures with their gelatinous predators, while in autumn they exhibited significant enrichment, possibly reflecting starvation or decay. Mixing models indicated that polychaetes constitute the second most important dietary component for A. aurita and M. leidyi during summer, after seston and zooplankton, respectively but declined in importance in autumn. These finding uncover a previously overlooked trophic pathway through which benthic prey subsidize pelagic consumers, strengthening benthic-pelagic coupling. Despite their lower observational frequency in M. leidyi, dietary models suggest ctenophores may exploit this resource opportunistically, with potential implications for competitive interactions and invasion dynamics. Our results highlight the need to incorporate living benthic-pelagic interactions into ecological models of energy flow and invasion ecology.

ecology↗

bioRxiv2025

CAR T cells targeting Nectin-4 safely overcome resistance to anti-Nectin-4 antibody-drug conjugate in solid tumors

Chimeric antigen receptor T (CAR T) cells represent a promising therapeutic option for a variety of cancers, including solid tumors. Nectin-4 is a cell adhesion molecule expressed at different levels in many solid tumors, including breast and urothelial carcinoma (UC). Enfortumab vedotin (EV), an antibody-drug conjugate (ADC) against Nectin-4, has significantly improved survival in patients with metastatic UC. Skin adverse reactions are frequently observed due to Nectin-4 expression in the epidermis. Here, we developed second-generation CAR T cells against Nectin-4 (N4CART) with a scFv that does not recognize human Nectin-4 expressed in skin keratinocytes. To study the effects of N4CART cell therapy, we used preclinical models of cell-derived xenografts (CDX) and patient-derived xenograft (PDX) of breast cancer expressing moderate to high levels of Nectin-4. We showed a marked efficacy with induction of remissions. Interestingly, N4CART cells kill Nectin-4-positive breast, urothelial and colon tumor cells, which are resistant to EV. Thus, N4CART cells represent a valuable and safe therapy for the treatment of patients with Nectin-4 expressing tumors, including those that are resistant to EV. Finally, baboon-envelope pseudotyped lentiviral vectors (LV) outperformed VSVG-LVs for Nectin-4 CAR expressing in {beta} T cells resulting in an efficient anti-tumoral response in PDX mice.

immunology↗

bioRxiv2025

Vascularized midbrain assembloids show neuroinflammation and dopaminergic neuron vulnerability in Parkinsons Disease

The use of micro-physiological systems has rapidly risen in the last years due to their translatability and complex cellular composition. Human midbrain-specific organoids contain neuroectoderm-derived cell types and are suitable for brain region-specific disease modeling. However, the lack of vasculature in these systems reduces oxygenation and nutrient supply. Furthermore, neurovascular interactions cannot be studied, and disease phenotypes affecting vascular and neurovascular structures cannot be assessed. To overcome these limitations, in this work, we successfully incorporated a vascular network into midbrain organoids by fusion with vascular organoids. Midbrain-vascular assembloids are enriched in vascular cells and microglia. We observed a decrease in hypoxia and cell death in these assembloids. Furthermore, microglia and endothelial cells increased their morphological complexity. Assembloids derived from a Parkinsons disease patient carrying a LRRK2-G2019S mutation displayed a pro-inflammatory phenotype and altered electrophysiological properties. Midbrain-vascular assembloids increase the midbrain model complexity and allow for neuroinflammation studies in Parkinsons disease.

neuroscience↗

bioRxiv2025

Lonafarnib Partially Reverses Cardiac Senescence in Human and Mouse Progeria Models via Autophagy Activation

Hutchinson-Gilford Progeria Syndrome (HGPS), characterised by accelerated ageing, causes cardiovascular defects resembling aspects of cardiovascular ageing. We used human left ventricle cardiomyocytes (CMs) derived from HGPS-induced pluripotent stem cells (iPSCs), and their isogenic-corrected controls, to investigate HGPS-CM dysfunction and identify potential therapies. Our results revealed that HGPS-iPSC-CMs exhibit greater maturity and associated elevated oxidative stress compared to controls, which they could not contend with, leading to cellular senescence. Increased senescence was also observed in cardiac tissue from mouse and human physiologically-aged and HGPS individuals. Functionally, HGPS-iPSC-CMs showed dysregulated mitochondrial respiration and calcium handling. Amongst the six drugs tested, rapamycin and lonafarnib were the most effective against HGPS-cardiac phenotypes. Although lonafarnib raised safety concerns, it partially reverted the cardiac senescent phenotype by inducing cellular autophagy and decreasing progerin expression in progeroid mice. Our study supports the use of HGPS-iPSC-CMs to identify novel biomarkers and therapies for HGPS, and potentially cardiac physiological-ageing.

cell biology↗

bioRxiv2025

Extracellular matrix mechanical cues (dys)regulate metabolic redox homeostasis due to impaired autophagic flux

Extracellular matrix (ECM) stiffness is increasingly recognized as a critical regulator of cellular behavior, governing processes such as proliferation, differentiation, and metabolism. Neurodegenerative diseases are characterized by mitochondrial dysfunction, oxidative stress, impaired autophagy, and progressive softening of the brain tissue, yet research into how mechanical cues influence cellular metabolism in this context remains scarce. In this study, we evaluated the long-term effects of brain-compliant, soft ECM on mitochondrial bioenergetics, redox balance, and autophagic capacity in neuronal cells. Using human neuroblastoma (SH-SY5Y) and mouse hippocampal (HT22) cell lines, as well as primary mouse neurons, we observed that prolonged exposure to soft ECM resulted in mitochondrial bioenergetic dysfunction, redox imbalance, and disrupted autophagic flux. These findings were consistently validated across both human and mouse neuronal cells. Our data indicate a decreased maximal autophagic capacity in cells exposed to long-term soft ECM, potentially due to an imbalance in autophagosome formation and degradation, as demonstrated by decreased LC3 II levels following chloroquine-induced autophagic flux inhibition. This impairment in autophagy was coupled with increased cellular oxidative stress, further indicating metabolic alterations. These findings emphasize the critical role of ECM stiffness in regulating neuronal cell metabolism and suggest that prolonged exposure to soft ECM may mimic key aspects of neurodegenerative disease pathology, thereby enhancing the physiological relevance of in vitro models. This study underscores the necessity for further research into ECM mechanics as a contributing factor in neurodegenerative disease progression and as a potential target for therapeutic strategies.

cell biology↗

bioRxiv2023

Physical activity regulates the immune response to breast cancer by a hematopoietic stem cell-autonomous mechanism

Physical activity is a modifiable lifestyle factor that is associated with a decreased risk for the development of breast cancer. While the exact mechanisms for the reduction in cancer risk due to physical activity are largely unknown, it is postulated that the biological reduction in cancer risk is driven by improvements in inflammation and immune function with exercise. Hematopoietic stem cells (HSCs) are the progenitor for all of the cells of the immune system and are involved in cancer immunosurveillance through differentiation into cytotoxic cell population. In this study, we investigate the role of physical activity (PA) in a spontaneously occurring model of breast cancer over time, with a focus on tumor incidence, circulating and tumor-infiltrating immune cells as well gene expression profiles of tumors and hematopoietic stem cells. Furthermore, we show that, in addition to a direct effect of PA on the immune cells of tumor-bearing mice, PA reduces the oxidative stress in HSCs of wildtype and tumor-bearing mice, and by doing so, alters the differentiation of the HSCs towards T cells in order to enhance cancer immunosurveillance.

cancer biology↗

bioRxiv2023

Cyclical control of female rejection behavior by progesterone receptor expressing neurons of the anterior ventromedial hypothalamus

Internal state-dependent behavioral responses, such as the switch between rejection and acceptance of sexual advances depending on a females reproductive capacity, are fundamental to maintain social interactions and wellbeing. Here we characterize a dedicated circuit for the cyclical control of rejection behavior in the mouse, located in the anterior ventrolateral ventromedial hypothalamus (aVMHvl). In vivo recordings reveal that progesterone receptor expressing neurons of the aVMHvl (aVMHvlPr+) are active during rejection but silent when females accept the male. Moreover, we show that aVMHvlPr+ neurons receive reduced excitatory to inhibitory synaptic input balance during the receptive phase of the reproductive cycle. Finally, optogenetic activation of aVMHvlPr+ neurons in receptive females is sufficient to increase rejection behavior, disrupting the probability of copulation, without affecting other male-directed interactions. This population of aVMHvlPr+ neurons is thus a key neural substrate controlling female sexual behavior, providing an additional barrier to mating when fertilization is not possible.

neuroscience↗

bioRxiv2022

A galanin-positive population of lumbar spinal cord neurons modulates sexual behavior and arousal

During sex, male arousal increases to the ejaculatory threshold, allowing genital sensory input to trigger ejaculation. While copulation and sexual arousal are thought to be centrally regulated by the brain, ejaculation is considered a reflex controlled by a spinal circuit. In this framework, the spinal cord is assumed to be strongly inhibited by descending input from the brain until the ejaculatory threshold, playing no role in the regulation of copulatory behavior. However, this remains untested. Here, we mapped the spinal circuit controlling the bulbospongiosus muscle, which is involved in sperm expulsion in mice. Our findings reveal that bulbospongiosus muscle-motor neurons receive input from galanin-expressing interneurons. This galanin-positive population receives genital input and, while its stimulation leads to bulbospongiosus muscle activity, the evoked muscle-potentials are dependent on spinalization, the males internal state and decrease with repeated stimulation. Moreover, ablation of galanin neurons affected the latency to ejaculate and altered the copulatory pattern. These results suggest an unexpected role of spinal circuits in the control of copulation and arousal, in addition to its established role in ejaculation.

neuroscience↗

bioRxiv2022

Skeletal muscle Nox4 knockout prevents and Nox2 knockout blunts loss of maximal diaphragm force in mice with heart failure with reduced ejection fraction

Patients with heart failure with reduced ejection fraction (HFrEF) experience diaphragm weakness that contributes to the primary disease symptoms of fatigue, dyspnea, and exercise intolerance. Weakness in the diaphragm is related to excessive production of reactive oxygen species (ROS), but the exact source of ROS remains unknown. NAD(P)H Oxidases (Nox), particularly the Nox2 and 4 isoforms, are important sources of ROS within skeletal muscle that contribute to optimal cell function. There are reports of increased Nox activity in the diaphragm of patients and animal models of HFrEF, implicating these complexes as possible sources of diaphragm dysfunction in HFrEF. To investigate the role of these proteins on diaphragm weakness in HFrEF, we generated inducible skeletal muscle specific knockouts of Nox2 or Nox4 using the Cre-Lox system and assessed diaphragm function in a mouse model of HFrEF induced by myocardial infarction. Diaphragm maximal specific force measured in vitro was depressed by ~20% with HFrEF. Knockout of Nox4 provided full protection against the loss of maximal force (p < 0.01), while the knockout of Nox2 provided partial protection (7% depression, p < 0.01). Mitochondrial respiration measured in permeabilized diaphragm muscle bundles increased with HFrEF or the knockout of Nox4 from skeletal muscle fibers (p < 0.05). Knockout of Nox2 from skeletal myofibers improved survival from 50 to 80% following myocardial infarction (p = 0.026). Our findings show an important role for skeletal muscle NAD(P)H Oxidases contributing to loss of diaphragm maximal force in HFrEF, along with systemic pathophysiological responses following myocardial infarction.

physiology↗

bioRxiv2021

Cardiac and respiratory muscle responses to dietary N-acetylcysteine in rats consuming a high-saturated fat, high-sucrose diet

BACKGROUNDExertional dyspnea is a significant clinical concern in individuals with overweight or obesity. The pathophysiology of dyspnea is multifactorial and complex. Previous data suggest that diaphragm and cardiac abnormalities should be considered as likely contributors to obesity-related exertional dyspnea. Additionally, oxidative stress is a causative factor in the general etiology of obesity as well as skeletal and cardiac muscle pathology. Thus, this preclinical study aimed to define diaphragm and cardiac morphological and functional alterations following an obesogenic diet in rats and the therapeutic potential of an antioxidant supplement, N-acetylcysteine (NAC). METHODSMale Wistar rats ([~]7 weeks old) consumed ad libitum either lean (20% protein, 70% carbohydrate, 10% fat) or high-saturated fat, high-sucrose (HFHS, 20% protein, 35% carbohydrate, 45% fat) diets for [~]22 weeks. Rats receiving HFHS diet were randomized to drink control water or water with NAC (2 mg/ml) for the last eight weeks of the dietary intervention: Lean, HFHS, and HFHS+NAC (n = 8 per group). We evaluated diaphragm bundles (in vitro function and histology) and hearts (weights and echocardiography) for all groups. RESULTSFinal body weights of HFHS rats, but not HFHS+NAC rats, were significantly higher than Lean controls. Neither HFHS diet nor NAC supplementation affected diaphragm specific force (N/cm2), peak power (W/kg), or morphology. In cardiac muscle, right and left ventricle weights (normalized to tibia length) of HFHS rats were greater than those of Lean controls and HFHS+NAC rats. Cardiac functional abnormalities were also present in HFHS rats, with left ventricular fractional shortening (%) and posterior wall maximal shortening velocity (cm/s) increasing compared to Lean controls, but HFHS+NAC rats did not demonstrate these markers of hypercontractility. HFHS rats showed an elevated deceleration rate of early transmitral diastolic velocity (E/DT) consistent with diastolic dysfunction, but NAC eliminated this effect. CONCLUSIONOur data suggest that an HFHS diet does not compromise diaphragm muscle morphology or in vitro function, suggesting other possible contributors to breathing abnormalities in obesity (e.g., neuromuscular transmission abnormalities). However, an HFHS diet resulted in cardiac hypertrophy, hypercontractility, and diastolic dysfunction. Supplementation with NAC did not affect diaphragm morphology or function but attenuated cardiac abnormalities in the HFHS diet. Our findings support future studies testing NAC supplementation in clinical trials of humans with obesity.

physiology↗