Biology subjects

Gill, A. L.

Publications and source records attributed to Gill, A. L..

8 recordsLinked to original sources

bioRxiv2026

Hyperglycemia and hyperfibrinogenemia alter Staphylococcus aureus abscess community morphology, antimicrobial susceptibility, and virulence in vitro.

Staphylococcus aureus is a prevalent human pathogen responsible for an array of invasive infections, such as osteomyelitis and bacteremia, which may be life threatening, recurrent, and cause permanent tissue damage. S. aureus infections are exacerbated in patients with co-morbidities including obesity and type 2 diabetes (obesity/T2D) due to impaired immune function, which leads to chronic inflammation and poor healing. Immune dysfunction can be attributed to gut microbiome dysbiosis, characterized by altered community composition and abundance, with aberrant production of gut-immune axis metabolites. Alongside the heightened infection susceptibility exhibited by obese/T2D hosts, S. aureus adapts to the hyperglycemic and hyperfibrinogenemic host environment for robust colonization. S. aureus can persist in host tissues by forming staphylococcal abscess communities (SACs) encapsulated by a fibrin pseudocapsule that protect the bacteria from antimicrobials and immune cell killing. Our current work aims to investigate how S. aureus adapts to the hyperglycemic and hyperfibrinogenemic obese/T2D environment. Our data show that two S. aureus clinical isolates, USA300 FPR3757 and JAR06.01.31, utilize fibrinogen differently in obese/T2D-like conditions to form unique pseudocapsule structures. Furthermore, RNAseq data show that in obese/T2D-like conditions, S. aureus upregulates virulence and tissue invasion gene expression. Additionally, our data suggest that antibiotic susceptibility in obese/T2D-like conditions is affected by antibiotic size, charge and metabolic activity of S. aureus. Collectively, these investigations will elucidate the impact of hyperglycemia and hyperfibrinogenemia on S. aureus abscess formation in two clinically relevant strains and may inform future therapies for obese/T2D patients. ImportanceType 2 diabetes associated with obesity creates a unique host environment that promotes the severity and persistence of Staphylococcus aureus infections. Elevated blood glucose and fibrinogen disrupt the normal immune response and create conditions that favor bacterial persistence and dissemination. S. aureus is an opportunistic pathogen capable of causing a broad spectrum of diseases ranging from skin infection to life threatening blood and bone infection. A critical step in its pathogenesis is the formation of abscesses, which shield the bacteria from immune clearance and antibiotic treatment. In this study, we demonstrate that the altered metabolic and inflammatory state of the obese diabetic host reshapes the way Staphylococcus aureus constructs these protective abscesses. We show that S. aureus modifies its use of host fibrin and adjusts its gene expression in response to high blood glucose and fibrinogen, thereby enhancing its ability to persist in host tissues.

microbiology↗

bioRxiv2024

Affective Symptoms in Pregnancy are Associated with the Vaginal Microbiome

Composition of the vaginal microbiome in pregnancy is associated with adverse maternal, obstetric, and child health outcomes. Identifying the sources of individual differences in the vaginal microbiome is therefore of considerable clinical and public health interest. The current study tested the hypothesis that vaginal microbiome composition during pregnancy is associated with an individuals experience of affective symptoms and stress exposure. Data were based on a prospective longitudinal study of a diverse and medically healthy community sample of 275 mother-infant pairs. Affective symptoms and stress exposure and select measures of associated biomarkers (diurnal salivary cortisol, serum measures of sex hormones) were collected at each trimester; self-report, clinical, and medical records were used to collect detailed data on socio-demographic factors and health behavior, including diet and sleep. Vaginal microbiome samples were collected in the third trimester (34-40 weeks) and characterized by 16S rRNA sequencing. Identified taxa were clustered into three community state types (CST1-3) based on dissimilarity of vaginal microbiota composition. Results indicate that depressive symptoms during pregnancy were reliably associated with individual taxa and CST3 in the third trimester. Prediction of functional potential from 16S taxonomy revealed a differential abundance of metabolic pathways in CST1-3 and individual taxa, including biosynthetic pathways for the neuroactive metabolites, serotonin and dopamine. With the exception of bioavailable testosterone, no significant associations were found between symptoms- and stress-related biomarkers and CSTs. Our results provide further evidence of how prenatal psychological distress during pregnancy alters the maternal-fetal microbiome ecosystem that may be important for understanding maternal and child health outcomes. ImportancePrenatal affective symptoms and stress are associated with maternal, obstetric, and child health outcomes, but the mechanisms underlying these links and their application to intervention remain unclear. The findings from this investigation extend prior microbiome-oriented research by demonstrating that the maternal vaginal microbiome composition has a biologically plausible mechanistic link with affective symptoms that also suggest additional clinical applications for assessment and intervention.

microbiology↗

bioRxiv2022

Impact of altering gut microbiota metabolism on osteomyelitis severity in obesity-related type 2 diabetes

Staphylococcus aureus is an opportunistic pathogen causing osteomyelitis through hematogenous seeding or contamination of implants and open wounds following orthopedic surgeries. The severity of S. aureus-mediated osteomyelitis is enhanced in obesity-related type 2 diabetes (obesity/T2D) due to chronic inflammation impairing both adaptive and innate immunity. Obesity-induced inflammation is linked to gut dysbiosis, with modification of the gut microbiota by high-fiber diets leading to a reduction in the symptoms and complications of obesity/T2D. However, our understanding of the mechanisms by which modifications of the gut microbiota alter host infection responses is limited. To address this gap, we monitored tibial S. aureus infections in obese/T2D mice treated with the inulin-like fructan fiber, oligofructose. Treatment with oligofructose significantly decreased S. aureus colonization and lowered proinflammatory signaling post-infection in obese/T2D mice, as observed by decreased circulating inflammatory cytokines (TNF-) and chemokines (IP-10, KC, MIG, MCP-1, and RANTES), indicating partial reduction in inflammation. Oligofructose markedly shifted diversity in the gut microbiota of obese/T2D mice mice, with notable increases in the anti-inflammatory bacterium, Bifidobacterium pseudolongum. Analysis of the cecum and plasma metabolome suggested polyamine production was increased, specifically spermine and spermidine. Oral administration of these polyamines to obese/T2D mice resulted in reduced infection severity similar to oligofructose supplementation, suggesting polyamines can mediate the beneficial effects of fiber on osteomyelitis severity. These results demonstrate the contribution of gut microbiota metabolites to the control of bacterial infections distal to the gut and polyamines as an adjunct therapeutic for osteomyelitis in obesity/T2D. ImportanceIndividuals with obesity-related type 2 diabetes (obesity/T2D) are at a five times increased risk for invasive Staphylococcus aureus osteomyelitis (bone infection) following orthopedic surgeries. With increasing antibiotic resistance and limited discoveries of novel antibiotics, it is imperative we explore other avenues for therapeutics. In this study, we demonstrated that the dietary fiber oligofructose markedly reduced osteomyelitis severity and hyperinflammation following acute implant-associated osteomyelitis in obese/T2D mice. Reduced infection severity is associated with changes in gut microbiota composition and metabolism as indicated by increased production of natural polyamines in the gut and circulating plasma. This work identifies a novel role for the gut microbiome in mediating control of bacterial infections and polyamines as beneficial metabolites involved in improving the obesity/T2D host response to osteomyelitis. Understanding the impact of polyamines on host immunity and mechanisms behind decreasing susceptibility to severe implant-associated osteomyelitis is crucial to improving treatment strategies for this patient population.

microbiology↗

bioRxiv2020

Type I PRMT inhibition protects against C9ORF72 arginine-rich dipeptide repeat toxicity

The most common genetic cause of amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) is a repeat expansion mutation in the C9orf72 gene. Repeat-associated non-AUG (RAN) translation of this expansion produces five species of dipeptide repeat proteins (DRPs). The arginine containing DRPs, polyGR and polyPR, are consistently reported to be the most toxic. Here, we uncover Type I protein arginine methyltransferase (PRMT) inhibitors as possible therapeutics for polyGR- and polyPR- related toxicity. Furthermore, we reveal data that suggest that asymmetric dimethylation (ADMe) of polyGR is a determining factor in its pathogenesis.

neuroscience↗

bioRxiv2020

Temporal Dysbiosis of Infant Nasal Microbiota Relative to Respiratory Syncytial Virus Infection

RationaleRespiratory Syncytial Virus (RSV) infection is a leading cause of infant respiratory disease and hospitalization. Infant airway microbiota occupying the nasopharynx have been associated with respiratory disease risk and severity. The extent to which interactions between RSV and microbiota occur in the airway, and their impact on respiratory disease severity and infection susceptibility, are not well understood. ObjectivesTo characterize associations between the nasal microbiota and RSV infection before, during, and after infants first respiratory illness. MethodsNasal 16S rRNA microbial community profiling of two cohorts of infants in the first year of life: 1) a cross-sectional cohort of 89 RSV infected infants sampled during illness and 102 population matched healthy controls, and 2) an individually matched longitudinal cohort of 12 infants who developed RSV infection and 12 who did not, sampled at time points before, during, and after infection. Measurements and Main ResultsWe identified 12 taxa significantly associated with RSV infection. All 12 were differentially abundant during infection, with seven differentially abundant prior to infection, and eight differentially abundant after infection. Eight of these taxa were associated with disease severity. Nasal microbiota composition was more discriminative of healthy vs. infected than of disease severity. ConclusionsOur findings elucidate the chronology of nasal microbiota dysbiosis and suggest an altered developmental trajectory associated with first-time RSV infection. Microbial temporal dynamics reveal indicators of disease risk, correlates of illness and severity, and the impact of RSV infection on microbiota composition. Identified taxa represent appealing targets for additional translationally-oriented research.

microbiology↗

bioRxiv2019

Coordinated Postnatal Trajectories of T Cells and Microbiota in Preterm and Full- term Newborns

Neonatal immune-microbiota co-development is poorly understood, yet appropriate recognition of - and response to - pathogens and commensal microbiota is critical to health. In this longitudinal study of 148 pre- and 119 full-term infants from birth through one year of age we found that postmenstrual age, or weeks from conception, not post-natal age, is the dominant factor influencing T cell and mucosal microbiota development. Numerous features of the T cell and microbiota functional development remain unexplained, however, by either age metric and are instead shaped by discrete peri- and post-natal events. Most strikingly, we establish that prenatal antibiotics or infection disrupt the normal T cell population developmental trajectory, influencing subsequent respiratory microbial colonization and predicting respiratory morbidity. In this way, early exposures imprint the postnatal immune-microbiota axis and place an infant at significant risk for respiratory morbidity in early childhood. One Sentence SummaryT cells and microbiota follow predictable, coordinated trajectories in newborns, and their coordination is an important determinant of illness in the first year. Graphical AbstractNasal and rectal microbiome was assessed weekly in the NICU, monthly post-discharge, and when respiratory illness symptoms occurred. T cells were characterized at birth (cord blood), 36-42 weeks postmenstrual age, and at 12 months. Quarterly respiratory morbidity surveys determined the 12-month outcome of persistent respiratory disease. More frequent illnesses and chronic disease outcomes occurred by one year of age if development of these systems was discordant or disrupted. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=142 SRC="FIGDIR/small/736090v3_ufig1.gif" ALT="Figure 1"> View larger version (28K): org.highwire.dtl.DTLVardef@1f08adeorg.highwire.dtl.DTLVardef@12d3671org.highwire.dtl.DTLVardef@151396borg.highwire.dtl.DTLVardef@190dcff_HPS_FORMAT_FIGEXP M_FIG C_FIG

immunology↗

bioRxiv2018

Neonate gut and respiratory microbiota: coordinated development through time and space

Background: Postnatal development of the microbiota in early life influences immunity, metabolism, neurodevelopment and long-term infant health. Microbiome development occurs at multiple body sites, each with distinct community compositions and functions. Associations between microbiota at multiple sites represent an unexplored influence on the infant microbiome. Here, we examined co-occurrence patterns of gut and respiratory microbiota in pre- and full-term infants over the first year of life, a period critical to neonatal development and risk of respiratory diseases.\n\nResults: Gut and respiratory microbiota collected as longitudinal rectal, throat and nasal samples from 38 pre-term and 44 full-term infants were first clustered into community state types (CSTs) on the basis of their composition. Multiple methods were used to relate the occurrence of CSTs to several measures of infant maturity, including gestational age (GA) at birth, week of life (WOL), and post menstrual age (PMA: equal to GA plus WOL). Manifestation of CSTs followed one of three patterns with respect to infant maturity. First, chronological: independent of infant maturity (GA) at birth, and strongly associated with post-natal age (WOL). Second, idiosyncratic: primarily dependent on maturity (GA) at birth, with persistent differences in CST occurrence between pre- and full-term infants through the first year of life. Third, convergent: CSTs appear earlier in infants with greater maturity (GA) at birth, but after a sufficient post-natal interval their occurrence in pre-term infants reaches parity with full-term infants. The composition of CSTs was highly dissimilar between different body sites, but the CST of any one body site was highly predictive of the CSTs at other body sites. There were significant associations between the abundance of individual taxa at each body site and the CSTs of the other body sites, which persisted after stringent control for the non-linear effects of infant maturity. Significant canonical correlations exist between the microbiota composition at each pair of body sites, with the strongest correlations between more proximal locations.\n\nConclusion: Cross-body site associations of developing infant microbiota suggest the importance of research and clinical practices that focus on dynamic interactions between multiple microbial communities to elucidate and promote systemic microbiota development.

developmental biology↗

bioRxiv2017

Efficacy of SHP2 phosphatase inhibition in cancers with nucleotide-cycling oncogenic RAS, RAS-GTP dependent oncogenic BRAF and NF1 loss

Oncogenic alterations in the RAS-RAF-MEK-ERK pathway, including mutant forms of KRAS, BRAF, and loss of the tumor suppressor and RAS GTPase-activating protein (GAP) NF1, drive the growth of a wide spectrum of human cancers. While BRAF and MEK inhibitors are effective in many patients with oncogenic BRAF V600E, there are no effective targeted therapies for individuals with cancers driven by other pathway alterations, including oncogenic KRAS, non-V600E BRAF, and NF1 loss. Here, we show that targeting the PTPN11/SHP2 phosphatase with a novel small molecule allosteric inhibitor is effective against cancers bearing nucleotide-cycling oncogenic RAS (e.g. KRAS G12C), RAS-GTP dependent oncogenic BRAF (e.g. class 3 BRAF mutants), or NF1 loss in multiple preclinical models in vitro and in vivo. SHP2 inhibition suppressed the levels of RAS-GTP and phosphorylated ERK in these models and induced growth inhibition. Expression of a constitutively active mutant of the RAS guanine nucleotide exchange factor (GEF) SOS1 rescued cells from the effects of SHP2 inhibition, suggesting that SHP2 blockade decreases oncogenic RAS-RAF-MEK-ERK signaling by disrupting SOS1-mediated RAS-GTP loading. Our findings illuminate a critical function for SHP2 in promoting oncogenic RAS activation and downstream signaling in cancers with nucleotide-cycling oncogenic RAS, RAS-GTP dependent oncogenic BRAF, and NF1 loss. SHP2 inhibition thus represents a rational, biomarker-driven therapeutic strategy to be tested in patients with cancers of diverse origins bearing these oncogenic drivers and for which current treatments are largely ineffective.

cancer biology↗