Biology subjects

Lloyd, C.

Publications and source records attributed to Lloyd, C..

8 recordsLinked to original sources

bioRxiv2026

Multimodal Connectome Markers of Disruptive Behavior Problems in Youth: Distinct Patterns of Concurrent Severity and Prospective Symptom Change

Disruptive behaviors problems, such as irritability/anger and maladaptive aggression, are associated with altered connectivity across networks supporting emotion regulation. However, multimodal connectome markers of concurrent severity and prospective symptom change, including sex-specific patterns, remain unclear. Using a large, sex-balanced sample from the Adolescent Brain Cognitive Development (ABCD) Study, we applied multimodal connectome-based predictive modelling (CPM) to test whether resting-state functional (n = 7,556; 49.3% female) and structural (N = 8,978; 48.4%) connectivity predicted baseline disruptive behavior severity (at ages 9-10) and 2-year symptom change (from ages 9-10 to 11-12). Models were adjusted for covariates, permutation-tested, and FDR corrected. Secondary analyses tested sex-stratified models separately in males and females. In models emerging as significant, follow-up analyses tested for distinct vs shared predictive edges. Functional and structural connectomes predicted baseline severity ({rho} = 0.087 and {rho} = 0.071, respectively). Functional connectivity also predicted prospective symptom change ({rho} = 0.038), whereas prospective structural prediction was predominately with negative edges ({rho} = 0.026). Functional connectivity models were significant in both sexes, while prospective structural connectivity models were significant in males, but not females. Frontoparietal, medial frontal, sensorimotor, salience, cerebellar, and visual networks contributed across models. Cross-sectional models showed a more distributed pattern while prospective models showed a more focal pattern. These findings identify complementary, largely distinct functional and structural connectome patterns associated with current disruptive behavior risk and subsequent symptom change, supporting the importance of developmental timing, sex, and imaging modality in developing brain-based biomarkers of disruptive behavior risk in youth.

neuroscience↗

bioRxiv2026

A Synthetic Archaeal Lipid Analog Enables Quantification of Substrate, Products, and Intermediates in the Tetraether Synthase Reaction

Glycerol dibiphytanyl glycerol tetraether (GDGT) and macrocyclic diether lipids (mAG) are unique membrane lipids predominantly found in archaea. Both lipids are composed of the same structural components: polar headgroups, glycerol backbones, and ether-linked 40-carbon biphytanyl chains. Tes, a member of the radical S-adenosylmethionine enzyme superfamily, synthesizes the biphytanyl chain by catalyzing carbon-carbon (C-C) bond formation between the terminal carbons of two phytanyl chains of the saturated diether lipid substrate. The coupling between the termini of two phytanyl chains on one glycerophospholipid yields mAG, whereas two couplings between the phytanyl termini of two glycerophospholipids yield GDGT. Quantification of the products and presumed intermediates formed during this multistep reaction has been challenging using mass spectrometry due to the lack of appropriate standards for each species. Herein, we designed and synthesized a diether lipid substrate analog containing a fluorescent/UV-visible tag linked to the headgroup, enabling the quantification of each species formed during a Tes reaction. Importantly, under laboratory conditions at 45 degrees C, we report that GDGT and mAG are initially formed in a 1:1.65 ratio, which differs considerably from the previously assumed ratio.

biochemistry↗

bioRxiv2026

Establishment of Galleria mellonella as a Model for Achromobacter xylosoxidans Infection

Achromobacter xylosoxidans (Ax) is an emerging pathogen with a strong capacity to adapt to different niches, but its pathogenesis is poorly understood. To investigate the virulence of this versatile bacterium, alternative infection models are valuable. Galleria mellonella wax moth presents cost and ethical advantages as an in vivo infection model. Here, we investigate the utility of Galleria as a model of Ax infection and demonstrate that mortality following Ax infection in Galleria recapitulates survival outcomes observed in infected mice. We further show that the Galleria infection model can be used to examine antimicrobial activity against Ax. Visualization of hemocytes suggested that Ax was internalized into immune cells, similar to what is observed in vertebrate models. Overall, our work establishes Galleria mellonella as a model of Ax infection that mirrors disease severity and innate immune cell interactions in murine models.

microbiology↗

bioRxiv2025

Pulmonary Hypertension Promotes Neuroinflammation and Neurodegeneration

IntroductionPulmonary arterial hypertension (PAH) is associated with neurocognitive deficits and abnormal brain MRI. Little is known about the mechanisms underlying these clinical observations. TDP-43 is a proteinopathy associated with frontotemporal lobar degeneration (FTLD), Alzheimers Disease, and Amyotrophic Lateral Sclerosis (ALS). In this study, we hypothesize PAH will result in gliosis, reduced neuronal density, and increased TDP-43 mislocalization. MethodsSprague Dawley rats were randomly assigned to receive Vehicle (DMSO) Monocrotaline, or Sugen/Hypoxia to induce PH. Right heart catheterization was used to confirm PAH. Brain tissue was fixed and probed for microglia (Iba1), astrocytes (GFAP), neurons (NeuN), and TDP-43. Human PH vs control brain tissue was also probed for NeuN and TDP-43. Results and ConclusionsWe identify an increase in microglia and astrocyte density in the frontal cortex along with reduced neuronal density and neuronal TDP-43 mislocalization in rat models of PH. In addition, human PH frontal cortex demonstrated neuronal TDP-43 mislocalization. This is the first evidence of TDP-43 proteinopathy in PH.

physiology↗

bioRxiv2025

Partial Wwox Loss of Function Increases Severity of Murine Sepsis and Neuroinflammation

RationaleWW domain-containing oxidoreductase (WWOX) is a gene associated implicated in both neurologic and inflammatory diseases and is susceptible to environmental stressors. We hypothesize partial loss of Wwox function will result in increased sepsis severity and neuroinflammation. MethodsWwox WT/P47T mice, generated by CRISPR/Cas9, and Wwox WT/WT mice were treated with intraperitoneal PBS vs LPS (10mg/kg) and euthanized 12 hours post-injection. Open Field Testing (OFT) and Murine Sepsis Severity Scores (MSS) were utilized to measure sickness behavior and sepsis severity, respectively. Brain tissue was analyzed using immunohistochemistry and PCR to measure neuroinflammation and apoptosis. ResultsWwox WT/P47T LPS mice demonstrated a more significant response to sepsis with an increase in sickness behavior, sepsis severity, gliosis, and apoptosis compared to Wwow WT/WT LPS littermates. ConclusionsPartial loss of Wwox function increases risk for severe sepsis and neuroinflammation. Given the susceptibility of WWOX to environmental stressors, this may be a target for future therapeutic interventions.

neuroscience↗

bioRxiv2024

Rigid, bivalent CTLA-4 binding to CD80 is required to disrupt the cis CD80 / PD-L1 interaction

The CTLA-4 and PD-1 checkpoints control immune responses to self-antigens and are key targets in cancer immunotherapy. Both pathways are connected via a cis interaction between CD80 and PD-L1, the ligands for CTLA-4 and PD-1 respectively. This cis interaction prevents PD-1 binding to PD-L1 but is reversed by CTLA-4 trans-endocytosis of CD80. However, the mechanism by which CTLA-4 selectively removes CD80 but not PD-L1 is unclear. Here we show that CTLA-4 - CD80 interactions are unimpeded by PD-L1 and that CTLA-4 binding with CD80 does not displace PD-L1 per se. Rather, both the rigidity and bivalency of the WT CTLA-4 molecule is required to orientate CD80 such that PD-L1 interactions are no longer permissible. Moreover, soluble CTLA-4 released PD-L1 only at specific expression levels of CD80 and PD-L1, whereas CTLA-4 trans-endocytosis released PD-L1 in all conditions. These data show that PD-L1 release from CD80 is driven by biophysical factors associated with orientation and bivalent cross-linking of proteins in the cell membrane and that trans-endocytosis of CD80 efficiently promotes PD-L1 availability.

immunology↗

bioRxiv2023

Characterizing Molecular and Synaptic Signatures in Mouse Models of Late-Onset Alzheimer's Disease Independent of Amyloid and Tau Pathology

Structured AbstractO_ST_ABSINTRODUCTIONC_ST_ABSMODEL-AD is creating and distributing novel mouse models with humanized, clinically relevant genetic risk factors to more accurately mimic LOAD than commonly used transgenic models. METHODSWe created the LOAD2 model by combining APOE4, Trem2*R47H, and humanized amyloid-beta. Mice aged up to 24 months were subjected to either a control diet or a high-fat/high-sugar diet (LOAD2+HFD) from two months of age. We assessed disease-relevant outcomes, including in vivo imaging, biomarkers, multi-omics, neuropathology, and behavior. RESULTSBy 18 months, LOAD2+HFD mice exhibited cortical neuron loss, elevated insoluble brain A{beta}42, increased plasma NfL, and altered gene/protein expression related to lipid metabolism and synaptic function. In vivo imaging showed age-dependent reductions in brain region volume and neurovascular uncoupling. LOAD2+HFD mice also displayed deficits in acquiring touchscreen-based cognitive tasks. DISCUSSIONCollectively the comprehensive characterization of LOAD2+HFD mice reveal this model as important for preclinical studies that target features of LOAD independent of amyloid and tau.

neuroscience↗

bioRxiv2022

Plcg2M28L interacts with high fat-high sugar diet to accelerate Alzheimers disease-relevant phenotypes in mice

Obesity is recognized as a significant risk factor for Alzheimers disease (AD). Studies have supported the notion that obesity accelerates AD-related pathophysiology in mouse models of AD. The majority of studies to date have focused on the use of early-onset AD models. Here we evaluate the impact of genetic risk factors on late-onset AD (LOAD) in mice fed a high fat/high sugar diet. We focused on three mouse models created through the IU/JAX/Pitt MODEL-AD Center, LOAD1, LOAD1.Plcg2M28L and LOAD1.Mthfr677C>T. At 2 months of age, animals were placed on a high fat/high sugar diet (HFD) that induces obesity, or a control diet (CD) that does not, until 12 months of age. Throughout the study, blood was collected to assess cholesterol and glucose. Positron emission tomography/computed tomography (PET/CT) was completed prior to sacrifice to image for glucose utilization and brain perfusion. At the completion of the study, blood and brains were collected for analysis. As expected, animals fed the HFD, regardless of genotype or sex, showed a significant increase in body weight compared to those fed the CD. Glucose and cholesterol increased as a function of HFD as well. Interestingly, LOAD1.Plcg2M28L demonstrated an increase in microglia density as well as alterations in regional brain glucose and perfusion when on a HFD. These changes were not observed in LOAD1 or LOAD1.Mthfr677C>T animals when fed a HFD. Furthermore, LOAD1.Plcg2M28L but not LOAD1.Mthfr677C>T or LOAD1 animals showed transcriptomics correlations to human AD modules. Our results show HFD affects brain health in a genotype-specific manner. Further insight into this process may have significant implications in the development of lifestyle interventions for treatment of AD.

neuroscience↗