Biology subjects

Palmer, C. S.

Publications and source records attributed to Palmer, C. S..

6 recordsLinked to original sources

bioRxiv2026

Metabolic reprogramming by caloric restriction enhances acute phase virological control and reduces chronic inflammation in SIV-infected rhesus macaques

Nutrient metabolism influences HIV-1 replication, antiviral immunity, and chronic inflammation, yet is difficult to leverage for therapeutic gain. We sought to modulate metabolism in the non-human primate model of HIV-1 by caloric restriction (CR), a modality canonically known for its antiaging benefits. Four months of 30% CR was safe and resulted in broad and systemic metabolic reprogramming in healthy adult male and female rhesus macaques. Relative to that of ad libitum-fed animals, CR lowered the frequencies of target CCR5+ CD4 T cells in the gut mucosa. Upon infection with SIV, CR reduced acute phase viremia, dampened type I interferon signaling, and overall permitted a more vigorous cycling of CD8+ T cells in lymphoid tissues. CR-induced protection from SIV was associated with a robust up-regulation of glycolysis, which supported an early reduction in viremia that ultimately waned over time. During virologic suppression with antiretroviral therapy (ART), CR significantly limited gastrointestinal (GI) immune activation, improved tricarboxylic acid cycle flux, and lowered concentrations of soluble CD14 and several TNF-related molecules in plasma. Blood SIV DNA levels however were unchanged by CR, suggesting that residual GI dysfunction and inflammation can be decoupled from viral persistence. Our findings highlight that a dietary modality can limit pathology in a primate lentiviral infection. They also reveal the robust but temporally constrained nature of glycolysis in supporting an acute antiviral response. SIGNIFICANCECaloric restriction (CR) is a safe dietary intervention known to confer anti-aging and health benefits across diverse animal models. However, its application in the context of infectious diseases has yielded mixed outcomes and has largely been limited to murine systems. In this study, we therefore employed CR to examine the impact of dietary modulation on SIV infection outcomes. Our findings demonstrate that CR reduced acute-phase viremia and attenuated markers of chronic inflammation following ART, effects that were associated with distinct metabolic signatures. Collectively, these findings underscore the importance of diet and nutrition in shaping chronic viral infection outcomes, such as SIV, within a clinically relevant non-human primate model.

immunology↗

bioRxiv2025

ASAP-ID: Proximity labelling with small tags

Biotinylation-based proximity labelling methods are valuable for discovering protein-protein interactions within cellular systems. However, one limitation of these approaches is that most require fusing the target protein with the enzyme that biotinylates nearby proteins (i.e., TurboID or APEX2), which risks sterically disrupting the proteins native function. Here, we present a method designed to reduce the steric impact of these fusions and offer greater flexibility in labelling modalities. The method, Antibody and Small-tag Assembly on Proteins for Interaction Detection (ASAP-ID), involves a bipartite system. Target proteins are fused to a small peptide antigen that recruits TurboID or APEX2 fused to an antibody directed to the antigen. Using two different antigen/antibody systems (SunTag and MoonTag), we show that ASAP-ID can specifically label human Lamin A in cells. The method works when the target protein and nanobody are co-expressed together in cis (ASAP-IDIC). We also demonstrate that the approach works when the antibody fusion is added in trans to fixed cells post-expression (ASAP-IDIT). ASAP-IDIT identified more than 448 known and previously undescribed interactors of lamin. We further used ASAP-IDIT to study how ALS-mutant profilin 1 affected its interactome. The method identified proteins involved in protein quality control that correlated with aggregation propensity. Moreover, the different mutants showed variation in the cellular location where aggregates formed. ASAP-IDIT revealed preferences for mitochondrial proteins for the two profilin mutants that tend to aggregate in the cytoplasm, C71G and M114T, and nuclear proteins for a mutant more prone to nuclear aggregation. These findings position ASAP-ID as a powerful addition to the proximity labelling toolkit, capable of probing subtle differences in interactomes in a less invasive manner.

biochemistry↗

bioRxiv2023

Immune Correlates of Hyperglycemia and Vaccination in a Non-human Primate Model of Long-COVID

Hyperglycemia, and exacerbation of pre-existing deficits in glucose metabolism, are major manifestations of the post-acute sequelae of SARS-CoV-2 (PASC). Our understanding of lasting glucometabolic disruptions after acute COVID-19 remains unclear due to the lack of animal models for metabolic PASC. Here, we report a non-human primate model of metabolic PASC using SARS-CoV-2 infected African green monkeys (AGMs). Using this model, we have identified a dysregulated chemokine signature and hypersensitive T cell population during acute COVID-19 that correlates with elevated and persistent hyperglycemia four months post-infection. This persistent hyperglycemia correlates with elevated hepatic glycogen, but there was no evidence of long-term SARS-CoV-2 replication in the liver and pancreas. Finally, we report a favorable glycemic effect of the SARS-CoV-2 mRNA vaccine, administered on day 4 post-infection. Together, these data suggest that the AGM metabolic PASC model exhibits important similarities to human metabolic PASC and can be utilized to assess therapeutic candidates to combat this syndrome.

immunology↗

bioRxiv2020

Non-Invasive Plasma Glycomic and Metabolic Biomarkers of Post-treatment Control of HIV

Non-invasive biomarkers that predict HIV remission after antiretroviral therapy (ART) interruption are urgently needed. Such biomarkers can improve the safety of analytic treatment interruption (ATI) and provide mechanistic insights into the pathways involved in post-ART HIV control. We identified plasma glycomic and metabolic signatures of time-to-viral-rebound and probability-of-viral-rebound using samples from two independent cohorts. These samples include a large number of post-treatment controllers, a rare population demonstrating sustained virologic suppression after ART-cessation. The signatures remained significant after adjusting for key demographic and clinical confounders. We also confirmed a mechanistic link between biomarkers and HIV latency reactivation and myeloid inflammation in vitro. Finally, machine learning algorithms selected sets of biomarkers that predict time-to-viral-rebound with 74-76% capacity and probability-of-viral-rebound with 97.5% capacity. In summary, we fill a major gap in HIV cure research by identifying non-invasive biomarkers, with potential functional significance, that predict duration and probability of viral remission after treatment interruption.

microbiology↗

bioRxiv2020

Proteomic identification of Coxiella burnetii effector proteins targeted to the host cell mitochondria during infection

Modulation of the host cell is integral to the survival and replication of microbial pathogens. Several intracellular bacterial pathogens deliver a cohort of bacterial proteins, termed effector proteins into the host cell during infection by sophisticated protein translocation systems which manipulate cellular processes and functions. Despite the importance of these proteins during infection the functional contribution of individual effectors is poorly characterised, particularly in intracellular bacterial pathogens with large effector protein repertoires. Technical caveats have limited the capacity to study these proteins during a native infection, with many effector proteins having only been demonstrated to be translocated during over-expression of tagged versions. Here we present development of a novel strategy to examine effector proteins in the context of infection. We coupled a broad, unbiased proteomics-based screen with organelle purification to study the host-pathogen interactions occurring between the host cell mitochondrion and the Gram-negative, Q fever pathogen Coxiella burnetii. We identify 4 novel mitochondrially-targeted C. burnetii effector proteins, renamed Mitochondrial Coxiella effector protein (Mce) B to E. Examination of the subcellular localisation of ectopically expressed proteins in epithelial cells confirmed the mitochondrial localisation, demonstrating the robustness of our approach. Subsequent biochemical analysis and affinity enrichment proteomics of one of these effector proteins, MceC, revealed the protein is imported into mitochondria and can interact with components of the mitochondrial quality control machinery. Our study adapts high-sensitivity proteomics to the study of intracellular host-pathogen interactions occurring during infection, providing a robust strategy to examine the sub-cellular localisation of effector proteins during native infection. This approach could be applied to a range of pathogens and host cell compartments to provide a rich map of effector dynamics throughout infection.

cell biology↗

bioRxiv2019

Neuronal-specific function of hTim8a in Complex IV assembly provides insight into the molecular mechanism underlying Mohr-Tranebjaerg syndrome

Human Tim8a is a member of an intermembrane space chaperone network, known as the small TIM family, which transport hydrophobic membrane proteins through this compartment. Mutations in TIMM8A cause a neurodegenerative disease, Mohr-Tranebjaerg syndrome (MTS), which is characterised by sensorineural hearing loss, dystonia and blindness. Nothing is known about the function of hTim8a in neuronal cells and consequently how lack of hTim8a leads to a neurodegenerative disease. We identified a novel cell-specific function of hTim8a in the assembly of Complex IV, which is mediated through a transient interaction with the copper chaperone COX17. Complex IV assembly defects in cells lacking hTim8a leads to oxidative stress and changes to key apoptotic regulators, including cytochrome c and Bax, which primes cells for cell death. Alleviation of oxidative stress using Vitamin E rescues cells from apoptotic vulnerability. We hypothesis that enhanced sensitivity of neuronal cells to apoptosis is the underlying mechanism of MTS.

cell biology↗