Biology subjects

Rasmussen, L.

Publications and source records attributed to Rasmussen, L..

10 recordsLinked to original sources

bioRxiv2026

BNIP3L/NIX-mediated mitophagy limits Alzheimer disease pathology and preserves neuronal function

Defective mitophagy is emerging as a key contributor to Alzheimer disease (AD), but the neuronal pathways governing mitochondrial clearance and their contribution to disease progression remain poorly understood. Here, we identify BNIP3L/NIX-dependent mitophagy as a conserved neuronal quality control pathway that maintains mitochondrial fitness and constrains AD-associated proteotoxicity. Loss of BNIP3L/NIX or its C. elegans orthologue DCT-1 impaired basal and stressed-induced mitophagy, disrupted mitochondrial homeostasis, enhanced Tau and Amyloid-beta pathology and compromised neuronal network, synaptic and behavioral function across human neuronal and in vivo models. Conversely, restoring BNIP3L/NIX and DCT-1 activity improved neuronal function under proteotoxic stress in vivo, reduced disease-associated Tau phosphorylation in human neurons and markedly suppressed seeded Tau aggregation in primary mouse neurons. Together, these findings identify BNIP3L/NIX-mediated mitophagy as a mechanistic link between mitochondrial quality control, proteostasis and neuronal function, and establish its restoration as a potential strategy for counteracting AD-associated pathology.

cell biology↗

bioRxiv2026

PDE4 Inhibitor Apremilast Rebalances Inflammatory Responses to Pseudomonas aeruginosa Infection in CF Rats

CFTR modulator therapies have transformed CF care, yet chronic airway inflammation persists in many people with cystic fibrosis (pwCF) even after long-term highly effective modulator therapy (HEMT). Because of the adverse side effects or the incompatibility with CFTR modulators, the use of traditional anti-inflammatory therapies is very limited in CF. Hence, new therapeutic strategies that rebalance inflammation without worsening infection with immunosuppression are needed. We evaluated the selective phosphodiesterase 4 (PDE4) inhibitor apremilast (Apr) for its ability to modulate dysregulated inflammation in humanized CF (G551D) rats acutely challenged with Pseudomonas aeruginosa. Apr is an approved anti-inflammatory therapeutic strategy for several chronic inflammatory conditions, but it has not been well studied in CF. In the humanized CF (G551D) rats, a short prophylactic Apr regimen significantly preserved lung function and reduced lung injury, accompanied by broad modulation of inflammatory responses, notably within Th1 and Th17 axes. Importantly, Apr did not cause a significant increase in bacterial burden. Just as importantly, Apr did not reduce CFTR mRNA or protein in vivo, and it increased G551D-CFTR phosphorylation critical for channel gating in vitro, supporting mechanistic compatibility with HEMT. These findings suggest Apr as a potential adjunct to CFTR modulators to rebalance airway inflammation while preserving host defense.

immunology↗

bioRxiv2023

A distinctive evolution of alveolar T cell responses is associated with clinical outcomes in unvaccinated patients with SARS-CoV-2 pneumonia

Pathogen clearance and resolution of inflammation in patients with pneumonia require an effective local T cell response. Nevertheless, local T cell activation may drive lung injury, particularly during prolonged episodes of respiratory failure characteristic of severe SARS-CoV-2 pneumonia. While T cell responses in the peripheral blood are well described, the evolution of T cell phenotypes and molecular signatures in the distal lung of patients with severe pneumonia caused by SARS-CoV-2 or other pathogens is understudied. Accordingly, we serially obtained 432 bronchoalveolar lavage fluid samples from 273 patients with severe pneumonia and respiratory failure, including 74 unvaccinated patients with COVID-19, and performed flow cytometry, transcriptional, and T cell receptor profiling on sorted CD8+ and CD4+ T cell subsets. In patients with COVID-19 but not pneumonia secondary to other pathogens, we found that early and persistent enrichment in CD8+ and CD4+ T cell subsets correlated with survival to hospital discharge. Activation of interferon signaling pathways early after intubation for COVID-19 was associated with favorable outcomes, while activation of NF-{kappa}B-driven programs late in disease was associated with poor outcomes. Patients with SARS-CoV-2 pneumonia whose alveolar T cells preferentially targeted the Spike and Nucleocapsid proteins tended to experience more favorable outcomes than patients whose T cells predominantly targeted the ORF1ab polyprotein complex. These results suggest that in patients with severe SARS-CoV-2 pneumonia, alveolar T cell interferon responses targeting structural SARS-CoV-2 proteins characterize patients who recover, yet these responses progress to NF-{kappa}B activation against non-structural proteins in patients who go on to experience poor clinical outcomes.

systems biology↗

bioRxiv2023

Alcohol-Induced Mucociliary Dysfunction: Role of Defective CFTR Channel Function

Excessive alcohol use is thought to increase the risk of respiratory infections by impairing mucociliary clearance (MCC). In this study, we investigate the hypothesis that alcohol reduces the function of CFTR, the protein that is defective in individuals with cystic fibrosis, thus altering mucus properties to impair MCC and the airways defense against inhaled pathogens. MethodsSprague Dawley rats with wild type CFTR (+/+), matched for age and sex, were administered either a Lieber-DeCarli alcohol diet or a control diet with the same number of calories for eight weeks. CFTR activity was measured using nasal potential difference (NPD) assay and Ussing chamber electrophysiology of tracheal tissue samples. In vivo MCC was determined by measuring the radiographic clearance of inhaled Tc99 particles and the depth of the airway periciliary liquid (PCL) and mucus transport rate in excised trachea using micro-optical coherence tomography ({micro}OCT). The levels of rat lung MUC5b and CFTR were estimated by protein and mRNA analysis. ResultsAlcohol diet was found to decrease CFTR ion transport in the nasal and tracheal epithelium in vivo and ex vivo. This decrease in activity was also reflected in partially reduced full-length CFTR protein levels but not, in mRNA copies, in the lungs of rats. Furthermore, alcohol-fed rats showed a significant decrease in MCC after 8 weeks of alcohol consumption. The trachea from these rats also showed reduced PCL depth, indicating a decrease in mucosal surface hydration that was reflected in delayed mucus transport. Diminished MCC rate was also likely due to the elevated MUC5b expression in alcohol-fed rat lungs. ConclusionsExcessive alcohol use can decrease the expression and activity of CFTR channels, leading to reduced airway surface hydration and impaired mucus clearance. This suggests that CFTR dysfunction plays a role in the compromised lung defense against respiratory pathogens in individuals who drink alcohol excessively. What is the current scientific knowledge on this subject?Excessive alcohol is associated with delayed mucociliary clearance (MCC) and an increased risk of respiratory infections among heavy drinkers. What does this study add to the field?Chronic alcohol use reduces CFTR activity and airway surface hydration explaining the mechanisms underlying mucociliary dysfunction. Acquired CFTR dysfunction may be a suitable target to improve host immunity in those affected by prolonged alcohol use.

pharmacology and toxicology↗

bioRxiv2023

MRE11A: a novel negative regulator of human DNA mismatch repair

DNA mismatch repair (MMR) is a highly conserved pathway that corrects DNA replication errors. Although well characterized, MMR factors remain to be identified. As a 3-5 exonuclease and endonuclease, meiotic recombination 11 homolog A (MRE11A) is implicated in multiple DNA repair pathways. However, the role of MRE11A in MMR is unclear. Here, we show that MRE11A deficiency increased the sensitivity of HeLa cells to N-methyl-N nitro-N nitrosoguanidine (MNNG) treatment, implying a potential role of MRE11 in MMR. Moreover, we found MRE11A was largely recruited to chromatin and negatively regulated the DNA damage signals within the first cell cycle after MNNG treatment. We also showed that knockdown of MRE11A increased, while overexpressing MRE11A decreased, MMR activity in HeLa cells, suggesting that MRE11A negatively regulates MMR activity. Furthermore, we show that the recruitment of MRE11A to chromatin requires MLH1 and that MRE11A competes with PMS2 for binding to MLH1. This decreases PMS2 levels in whole cell and on chromatin, and consequently comprises MMR activity. Collectively, our findings reveal that MRE11A is a negative regulator of human MMR.

molecular biology↗

bioRxiv2022

Selective Androgen Receptor Modulator Microparticle Formulation Reverses Muscle Hyperalgesia in Mouse Model of Widespread Muscle Pain

Currently, there is a need for the generation of non-opioid analgesics for treating chronic pain. Preclinical and clinical studies demonstrate the analgesic effects of testosterone. However, treatment with testosterone is not feasible due to adverse effects. Selective androgen receptor modulators (SARMs) were developed to overcome these limitations by minimizing activation of androgenic side effects. First, we demonstrate SARM administration alleviates widespread muscle pain in male and female mice. We then developed a SARM-loaded PLGA microparticle formulation that reverses widespread muscle pain in two injections. In vitro and in vivo release kinetics demonstrate the microparticle formulation had sustained SARM release for 4 weeks. Antagonism of androgen receptors blocked the analgesic effects of the SARM microparticles. SARM treatment had no effect on cardiac or liver enzymes, cardiac histology, and did not produce rewarding behavior. These studies demonstrate SARM microparticles as a potential therapeutic for chronic muscle pain. One Sentence SummaryA selective androgen receptor modulator microparticle formulation alleviates widespread muscle pain in male and female mice while being non-toxic.

neuroscience↗

bioRxiv2021

Novel compound inhibitors of HIV-1NL4-3 Vpu

HIV-1 Vpu targets the host cell proteins CD4 and BST-2/Tetherin for degradation, ultimately resulting in enhanced virus spread and host immune evasion. The discovery and characterization of small molecules that antagonize Vpu would further elucidate the contribution of Vpu to pathogenesis and lay the foundation for the study of a new class of novel HIV-1 therapeutics. To identify novel compounds that block Vpu activity, we developed a cell-based gain of function assay that produces a positive signal in response to Vpu inhibition. To develop this assay, we took advantage of the viral glycoprotein, GaLV Env. In the presence of Vpu, GaLV Env is not incorporated into viral particles, resulting in non-infectious virions. Vpu inhibition restores infectious particle production. Using this assay, a high throughput screen of >650,000 compounds was performed to identify inhibitors that block the biological activity of Vpu. From this screen, we identified several positive hits but focused on two compounds from one structural family, SRI-41897 and SRI-42371. It was conceivable that the compounds inhibited the formation of infectious virions by targeting host cell proteins instead of Vpu directly, so we developed independent counter-screens for off target interactions of the compounds and found no off target interactions. Additionally, these compounds block Vpu-mediated modulation of CD4, BST-2/Tetherin and antibody dependent cell-mediated toxicity (ADCC). Unfortunately, both SRI-41897 and SRI-42371 were shown to be specific to the N-terminal region of NL4-3 Vpu and did not function against other, more clinically relevant, strains of Vpu.

microbiology↗

bioRxiv2020

Drug Repurposing Screen for Compounds Inhibiting the Cytopathic Effect of SARS-CoV-2

Drug repurposing is a rapid approach to identifying therapeutics for the treatment of emerging infectious diseases such as COVID-19. To address the urgent need for treatment options, we carried out a quantitative high-throughput screen using a SARS-CoV-2 cytopathic assay with a compound collection of 8,810 approved and investigational drugs, mechanism-based bioactive compounds, and natural products. Three hundred and nineteen compounds with anti-SARS-CoV-2 activities were identified and confirmed, including 91 approved drug and 49 investigational drugs. Among these confirmed compounds, the anti-SARS-CoV-2 activities of 230 compounds, including 38 approved drugs, have not been previously reported. Chlorprothixene, methotrimeprazine, and piperacetazine were the three most potent FDA approved drugs with anti-SARS-CoV-2 activities. These three compounds have not been previously reported to have anti-SARS-CoV-2 activities, although their antiviral activities against SARS-CoV and Ebola virus have been reported. These results demonstrate that this comprehensive data set of drug repurposing screen for SARS-CoV-2 is useful for drug repurposing efforts including design of new drug combinations for clinical trials.

microbiology↗

bioRxiv2020

The SARS-CoV-2 cytopathic effect is blocked with autophagy modulators

SARS-CoV-2 is a new type of coronavirus capable of rapid transmission and causing severe clinical symptoms; much of which has unknown biological etiology. It has prompted researchers to rapidly mobilize their efforts towards identifying and developing anti-viral therapeutics and vaccines. Discovering and understanding the virus’ pathways of infection, host-protein interactions, and cytopathic effects will greatly aid in the design of new therapeutics to treat COVID-19. While it is known that chloroquine and hydroxychloroquine, extensively explored as clinical agents for COVID-19, have multiple cellular effects including inhibiting autophagy, there are also dose-limiting toxicities in patients that make clearly establishing their potential mechanisms-of-action problematic. Therefore, we evaluated a range of other autophagy modulators to identify an alternative autophagy-based drug repurposing opportunity. In this work, we found that 6 of these compounds blocked the cytopathic effect of SARS-CoV-2 in Vero-E6 cells with EC50 values ranging from 2.0 to 13 µM and selectivity indices ranging from 1.5 to >10-fold. Immunofluorescence staining for LC3B and LysoTracker dye staining assays in several cell lines indicated their potency and efficacy for inhibiting autophagy correlated with the measurements in the SARS-CoV-2 cytopathic effect assay. Our data suggest that autophagy pathways could be targeted to combat SARS-CoV-2 infections and become an important component of drug combination therapies to improve the treatment outcomes for COVID-19.One Sentence Summary Blocking SARS-CoV-2 cytopathic effects with selective autophagy inhibitors underlying the clinical benefits of chloroquine and hydroxychloroquine.Competing Interest StatementThe authors have declared no competing interest.View Full Text

pharmacology and toxicology↗

bioRxiv2020

Regular physical activity reduces the percentage of spinally projecting neurons that express mu-opioid receptors from the RVM

Regular physical activity/exercise is an effective non-pharmacological treatment for individuals with chronic pain. Central inhibitory mechanisms, involving serotonin and opioids, are critical to analgesia produced by regular physical activity. The RVM sends projections to the spinal cord to inhibit or facilitate nociceptive neurons and plays a key role in exercise-induced analgesia. The goal of these studies was to examine if regular physical activity modifies RVM-spinal cord circuitry. Male and female mice received Fluoro-Gold placed on the spinal cord to identify spinally projecting neurons from the rostral ventromedial medulla (RVM) and the nucleus raphe obscuris/nucleus raphe pallidus (NRO/NRP), dermorphin-488 into caudal medulla to identify mu-opioid receptors, and were immunohistochemically stained for either phosphorylated-N-methyl-D-aspartate subunit NR1 (p-NR1) to identify excitatory neurons or tryptophan hydroxylase (TPH) to identify serotonin neurons. The percentage of dermorphin-488-positive cells that stained for p-NR1 (or TPH), and the percentage of dermorphin-488-positive cells that stained for p-NR1 (or TPH) and Fluoro-Gold was calculated. Physically active animals were provided running wheels in their cages for 8 weeks and compared to sedentary animals without running wheels. Animals with chronic muscle pain, induced by two intramuscular injections of pH 4.0, were compared to sham controls (pH 7.2). Physically active animals had less mu-opioid expressing neurons projecting to the spinal cord when compared to sedentary animals in the RVM, but not the NRO/NRP. No changes were observed for TPH. These data suggest that regular exercise alters central facilitation so that there is less descending facilitation to result in a net increase in inhibition. Summary StatementPhysically active animals has less mu-opioid expressing neurons projecting to the spinal cord in the RVM, but not the NRO/NRP, when compared to sedentary animals.

neuroscience↗