Biology subjects

Adams, L. G.

Publications and source records attributed to Adams, L. G..

9 recordsLinked to original sources

bioRxiv2024

Late-life dietary folate restriction reduces biosynthetic processes without compromising healthspan in mice

Folate is a vitamin required for cell growth and is present in fortified foods in the form of folic acid to prevent congenital abnormalities. The impact of low folate status on life-long health is poorly understood. We found that limiting folate levels with the folate antagonist methotrexate increased the lifespan of yeast and worms. We then restricted folate intake in aged mice and measured various health metrics, metabolites, and gene expression signatures. Limiting folate intake decreased anabolic biosynthetic processes in mice and enhanced metabolic plasticity. Despite reduced serum folate levels in mice with limited folic acid intake, these animals maintained their weight and adiposity late in life, and we did not observe adverse health outcomes. These results argue that the effectiveness of folate dietary interventions may vary depending on an individuals age and sex. A higher folate intake is advantageous during the early stages of life to support cell divisions needed for proper development. However, a lower folate intake later in life may result in healthier aging.

molecular biology↗

bioRxiv2023

Peptide-mimetic treatment of Pseudomonas aeruginosa in a mouse model of respiratory infection

The rise of drug resistance has become a global crisis, with >1 million deaths due to resistant bacterial infections each year. Pseudomonas aeruginosa, in particular, remains a serious problem with limited solutions due to complex resistance mechanisms that now lead to more than 32,000 multidrug-resistant (MDR) infections and over 2,000 deaths annually. While the emergence of resistant bacteria has become concerningly common, identification of useful new drug classes has been limited over the past 40+ years. We found that a potential novel therapeutic, the peptide-mimetic TM5, is effective at killing P. aeruginosa and displays sufficiently low toxicity for mammalian cells to allow for use in treatment of infections. Interestingly, TM5 kills P. aeruginosa more rapidly than traditional antibiotics, within 30-60 minutes in vitro, and is effective against a range of clinical isolates. In vivo, TM5 significantly reduced bacterial load in the lungs within 24 hours compared to untreated mice and demonstrated few adverse effects. Taken together, these observations suggest that TM5 shows promise as an alternative therapy for MDR P. aeruginosa respiratory infections.

microbiology↗

bioRxiv2023

Identification of a genetic region in linked to tolerance to MRSA infection using Collaborative Cross mice.

Staphylococcus aureus (S. aureus) colonizes humans asymptomatically but can also cause opportunistic infections, ranging from mild skin infections to severe life-threatening conditions. Resistance and tolerance are two ways a host can survive an infection. Resistance is limiting the pathogen burden, while tolerance is limiting the health impact of a given pathogen burden. In previous work, we established that collaborative cross (CC) mouse line CC061 is highly susceptible to Methicillin-resistant S. aureus infection (MRSA, USA300), while CC024 is tolerant. To identify host genes involved in tolerance after S. aureus infection, we crossed CC061 mice and CC024 mice to generate F1 and F2 populations. Survival after MRSA infection in the F1 and F2 generations was 65% and 45% and followed a complex dominant-recessive inheritance pattern. Colonization in F2 animals was more extreme than in their parents, suggesting successful segregation of genetic factors. We identified a QTL peak on chromosome 7 for survival and weight change after infection. In this QTL, the WSB allele was present in CC024 mice and contributed to their MRSA tolerant phenotype. Two genes, C5ar1 and C5ar2, have high-impact variants in this region. The complement factor, C5a, is an anaphylatoxin that can trigger a massive immune response by binding to its receptors, C5ar1 and C5ar2. We hypothesize that C5a may have altered binding to variant receptors in CC024 mice, reducing damage caused by the cytokine storm and resulting in the ability to tolerate a higher pathogen burden and longer survival. ImportanceStaphylococcus aureus causes a wide range of diseases in humans. Resistance and tolerance are two ways a host can survive an infection. Resistance is limiting the pathogen burden, while tolerance is limiting the health impact of a given pathogen burden. Tolerance mechanisms are poorly understood in context of host-pathogen interaction. To identify host genes involved in tolerance after S. aureus infection, we crossed CC061 mice and CC024 mice. The genetic factors controlling tolerance were well segregated in the F2 population. Using QTL mapping, we identified a significant peak on chromosome 7 for survival and weight change after infection. Two genes, C5ar1 and C5ar2, have high-impact variants in this region. We hypothesize that C5a may have altered binding to variant receptors in CC024 mice, reducing damage caused by the cytokine storm and resulting in the ability to tolerate a higher pathogen burden and longer survival.

genetics↗

bioRxiv2023

Collaborative Cross mice have diverse phenotypic responses to infection with Methicillin-resistant Staphylococcus aureus USA300

Staphylococcus aureus (S. aureus) is an opportunistic pathogen causing diseases ranging from mild skin infections to life threatening conditions, including endocarditis, pneumonia, and sepsis. To identify host genes modulating this host-pathogen interaction, we infected 25 Collaborative Cross (CC) mouse strains with methicillin-resistant S. aureus (MRSA) and monitored disease progression for seven days using a surgically implanted telemetry system. CC strains varied widely in their response to intravenous MRSA infection. We identified eight susceptible CC strains with high bacterial load, tissue damage, and reduced survival. Among the surviving strains, six with minimal colonization were classified as resistant, while the remaining six tolerated higher organ colonization ( tolerant). The kidney was the most heavily colonized organ, but liver, spleen and lung colonization were better correlated with reduced survival. Resistant strains had higher pre-infection circulating neutrophils and lower post-infection tissue damage compared to susceptible and tolerant strains. We identified four CC strains with sexual dimorphism: all females survived the study period while all males met our euthanasia criteria earlier. In these CC strains, males had more baseline circulating monocytes and red blood cells. We identified several CC strains that may be useful as new models for endocarditis, myocarditis, pneumonia, and resistance to MRSA infection. Quantitative Trait Locus (QTL) analysis identified two significant loci, on Chromosomes 18 and 3, involved in early susceptibility and late survival after infection. We prioritized Npc1 and Ifi44l genes as the strongest candidates influencing survival using variant analysis and mRNA expression data from kidneys within these intervals. Author SummaryMethicillin-resistant Staphylococcus aureus is a human opportunistic pathogen that can cause life-threatening diseases. To study the influence of host genetics on the outcome of MRSA infection, we infected a collection of genetically diverse mice. We identified different phenotypes for survival, organ colonization, and tissue damage, and classified CC strains into MRSA susceptible, tolerant, and resistant categories. We identified several parameters that correlated with these phenotypes. Four CC strains exhibited strong sexual dimorphism in infection outcome: females lived longer, and males had higher baseline circulating monocytes and red blood cells. Several of the CC strains we characterize may represent better animal models for diseases caused by MRSA. QTL analysis identified two genes, Npc1 and Ifi44l, as strong candidates for involvement in early susceptibility and late survival after MRSA infection. Our data suggests a strong involvement of host genetics in MRSA infection outcome.

microbiology↗

bioRxiv2023

Precision pharmacological reversal of genotype-specific diet-induced metabolic syndrome in mice informed by transcriptional regulation

Diet-related metabolic syndrome is the largest contributor to adverse health in the United States. However, the study of gene-environment interactions and their epigenomic and transcriptomic integration is complicated by the lack of environmental and genetic control in humans that is possible in mouse models. Here we exposed three mouse strains, C57BL/6J (BL6), A/J, and NOD/ShiLtJ (NOD), to a high-fat high-carbohydrate diet, leading to varying degrees of metabolic syndrome. We then performed transcriptomic and genomic DNA methylation analyses and found overlapping but also highly divergent changes in gene expression and methylation upstream of the discordant metabolic phenotypes. Strain-specific pathway analysis of dietary effects reveals a dysregulation of cholesterol biosynthesis common to all three strains but distinct regulatory networks driving this dysregulation. This suggests a strategy for strain-specific targeted pharmacologic intervention of these upstream regulators informed by transcriptional regulation. As a pilot study, we administered the drug GW4064 to target one of these genotype-dependent networks, the Farnesoid X receptor pathway, and found that GW4064 exerts genotype-specific protection against dietary effects in BL6, as predicted by our transcriptomic analysis, as well as increased inflammatory-related gene expression changes in NOD. This pilot study demonstrates the potential efficacy of precision therapeutics for genotype-informed dietary metabolic intervention, and a mouse platform for guiding this approach.

genetics↗

bioRxiv2022

Taxonomic and metagenomic analyses define the development of the microbiota in the chick

Chicks are ideal to follow the development of the intestinal microbiota and to understand how a pathogen perturbs this developing population. Taxonomic/metagenomic analyses captured the development of the chick microbiota in unperturbed chicks and in chicks infected with Salmonella enterica serotype Typhimurium (STm) during development. Taxonomic analysis suggests that colonization by the chicken microbiota takes place in several waves. The cecal microbiota stabilizes at day 12 post-hatch with prominent Gammaproteobacteria and Clostridiales. Introduction of S. Typhimurium at day 4 post-hatch disrupted the expected waves of intestinal colonization. Taxonomic and metagenomic shotgun sequencing analyses allowed us to identify species present in uninfected chicks. Untargeted metabolomics suggested different metabolic activities in infected chick microbiota. This analysis, and GS-MS on ingesta confirmed that lactic acid in cecal content coincides with the stable presence of Enterococci in STm infected chicks. Unique metabolites including 2-isopropylmalic acid, an intermediate in the biosynthesis of leucine, was present only in the cecal content of STm infected chicks. Metagenomic data suggested that the microbiota in STm infected chicks contained a higher abundance of genes, from STm itself, involved in branched chain amino acid synthesis. We generated a deletion mutant in ilvC (STM3909) encoding ketol-acid-reductoisomerase, a gene required for the production of L-isoleucine and L-valine. {Delta}ilvC mutants are disadvantaged for growth during competitive infection with the wild type. Providing the ilvC gene in trans restored growth of the {Delta}ilvC mutant. Our integrative approach identified biochemical pathways used by STm to establish a colonization niche in the chick intestine during development. IMPORTANCEChicks are an ideal model to follow the development of the intestinal microbiota and to understand how a pathogen perturbs this developing population. Using taxonomic and metagenomic analyses we captured the development of the chick microbiota to 19 days post-hatch in unperturbed chicks and in chicks infected with Salmonella enterica serotype Typhimurium (STm). We show that normal development of the microbiota takes place in waves, and is altered in the presence of a pathogen. Metagenomics and metabolomics suggested that branched chain amino acid biosynthesis is especially important for Salmonella growth in the infected chick intestine. Salmonella mutants unable to make L-isoleucine and L-valine colonize the chick intestine poorly. Restoration of the pathway for biosynthesis of these amino acids restored the colonizing ability of Salmonella. Integration of multiple analyses allowed us to correctly identify biochemical pathways used by Salmonella to establish a niche for colonization in the chick intestine during development.

microbiology↗

bioRxiv2022

Borrelia burgdorferi engages mammalian type I interferon responses via the cGAS-STING pathway

Borrelia burgdorferi, the etiologic agent of Lyme disease, is a spirochete that modulates numerous host pathways to cause a chronic, multi-system inflammatory disease in humans. B. burgdorferi infection can lead to Lyme carditis, neurologic complications, and arthritis, due to the ability of specific borrelial strains to disseminate, invade, and drive inflammation. B. burgdorferi elicits type I interferon (IFN-I) responses in mammalian cells and tissues that are associated with the development of severe arthritis or other Lyme-related complications. However, the innate immune sensors and signaling pathways controlling IFN-I induction remain unclear. In this study, we examined whether intracellular nucleic acid sensing is required for the induction of IFN-I to B. burgdorferi. Using fluorescence microscopy, we show that B. burgdorferi associates with mouse and human cells in culture and we document that internalized spirochetes co-localize with the pattern recognition receptor cyclic GMP-AMP synthase (cGAS). Moreover, we report that IFN-I responses in mouse macrophages and murine embryonic fibroblasts are significantly attenuated in the absence cGAS or its adaptor Stimulator of Interferon Genes (STING), which function to sense and respond to intracellular DNA. Longitudinal in vivo tracking of bioluminescent B. burgdorferi revealed similar dissemination kinetics and borrelial load in C57BL/6J wild-type, cGAS-deficient, or STING-deficient mice. However, infection-associated tibiotarsal joint pathology and inflammation were modestly reduced in cGAS-deficient compared to wild-type mice. Collectively, these results indicate that the cGAS-STING pathway is a critical mediator of mammalian IFN-I signaling and innate immune responses to B. burgdorferi. KEY POINTSO_LIB. burgdorferi triggers type I interferon responses in macrophages and fibroblasts C_LIO_LICoiled spirochetes are observed in the cytosol and co-localize with cGAS C_LIO_LIcGAS and STING mediate B. burgdorferi-induced type I interferon responses C_LI

immunology↗

bioRxiv2022

Elucidating Mechanisms of Tolerance to Salmonella Typhimurium Across Long-Term Infections Using the Collaborative Cross

Understanding the molecular mechanisms underlying resistance and tolerance to pathogen infection may present the opportunity to develop novel interventions. Resistance is the absence of clinical disease with low pathogen burden, while tolerance is minimal clinical disease in the face of high pathogen burden. Salmonella is a worldwide health concern. We studied 18 strains of Collaborative Cross mice that survive acute Salmonella Typhimurium (STm) infections. We infected these strains orally and monitored them for three weeks post-infection. Five strains cleared STm by the end of the experiment (resistant), while 6 strains maintained a bacterial load and survived to the end of the experiment (tolerant). The remaining 7 strains survived longer than 7 days but succumbed to infection before the end of the study period and were called "delayed susceptible" to differentiate them from strains that do not survive to day 7 (susceptible). Tolerant strains were colonized in Peyers patches, mesenteric lymph node, spleen and liver, while resistant strains had significantly reduced bacterial colonization. Tolerant strains had lower pre-infection core body temperatures than both delayed susceptible and resistant strains and had disrupted circadian patterns of body temperature post-infection sooner than resistant strains. Tolerant strains had higher circulating total white blood cells than resistant strains, driven by increased numbers of neutrophils. Tolerant strains had more severe tissue damage and higher circulating levels of MCP-1 and IFN-{gamma}, but lower levels of ENA-78 than resistant strains. QTL analysis revealed 1 significant association and 6 suggestive associations. RNA-seq analysis identified 22 genes that are differentially regulated in tolerant versus resistant animals that overlapped with the QTLs we identified and allowed us to identify the top 5 canonical pathways. Fibrinogen genes (Fga, Fgb, and Fgg) were found across the QTL, RNA, and top canonical pathways making them the best candidate genes for differentiating tolerance and resistance. Author SummaryAn infected host can respond in multiple ways to bacterial infection including resistance and tolerance. Resistance is a decrease in pathogen load, while in tolerance mild clinical signs are present despite high pathogen load. We infected a collection of 18 strains of genetically diverse mice with Salmonella Typhimurium for up to three weeks. Five strains were resistant, 6 strains were tolerant, and the remaining 7 strains survived an intermediate amount of time ("delayed susceptible"). Tolerant strains maintained bacterial load across several organs, while resistant strains reduced bacterial load. Tolerant strains had the lowest pre-infection core body temperatures and the most rapid disruption in circadian patterns of body temperature post-infection. Tolerant strains had higher circulating neutrophils, higher circulating levels of MCP-1 and IFN-{gamma}, but lower levels of ENA-78 than resistant strains, in addition to more severe tissue damage than resistant strains. QTL analysis revealed multiple associated regions, and gene expression analysis identified 22 genes that are differentially regulated in tolerant versus resistant animals in these regions. Fibrinogen genes (Fga, Fgb, and Fgg) were found across the QTL, RNA, and top canonical pathways making them the best candidate genes for differentiating tolerance and resistance.

genetics↗

bioRxiv2022

Genetic background influences survival of infections with Salmonella enterica serovar Typhimurium in the Collaborative Cross

Salmonella infections typically cause self-limiting gastroenteritis, but in some individuals these bacteria can spread systemically and cause disseminated disease. Salmonella Typhimurium (STm), which causes severe systemic disease in most inbred mice, has been used as a model for disseminated disease. To screen for new infection phenotypes across a range of host genetics, we orally infected 32 Collaborative Cross (CC) mouse strains with STm and monitored their disease progression for seven days by telemetry. Our data revealed a broad range of phenotypes across CC strains in many parameters including survival, bacterial colonization, tissue damage, complete blood counts (CBC), and serum cytokines. Eighteen CC strains survived to day 7, while fourteen susceptible strains succumbed to infection before day 7. Several CC strains had sex differences in survival and colonization. Surviving strains had lower pre-infection baseline temperatures and were less active during their daily active period. Core body temperature disruptions were detected earlier after STm infection than activity disruptions, making temperature a better detector of illness. All CC strains had STm in spleen and liver, but susceptible strains were more highly colonized. Tissue damage was weakly negatively correlated to survival. We identified loci associated with survival on Chromosomes (Chr) 1, 2, 4, 7. Polymorphisms in Ncf2 and Slc11a1, known to reduce survival in mice after STm infections, are located in the Chr 1 interval, and the Chr 7 association overlaps with a previously identified QTL peak called Ses2. We identified two new genetic regions on Chr 2 and 4 associated with susceptibility to STm infection. Our data reveal the diversity of responses to STm infection across a range of host genetics and identified new candidate regions for survival of STm infection. Author SummarySalmonella Typhimurium (STm) infections typically cause self-limiting diarrheal symptoms, but in some individuals, the bacteria can spread throughout the body and cause life-threatening infection. We used a population of genetically different mice (Collaborative Cross) to identify their range of responses to STm infection. We identified a broad range of outcomes across these different mice, including a group of mice susceptible to lethal infection and a group that survived our 7 day study. We found that mice that survived STm infection had a cooler core body temperature before infection than susceptible mice, while remaining active. Thus, body temperature, rather than activity, appears to be a better predictor of poor outcomes after STm infection. We identified several regions of the mouse genome that are associated with outcome after STm infection. One of these regions, mouse Chromosome (Chr) 1 has genes that are already known to influence susceptibility to STm infection. Two other regions that we identified to influence survival after STm infection, located on mouse Chr 2 and 4, are novel and contain numerous genes of interest that may be linked to susceptibility. Our work defines the utility of exploring how host genetic diversity influences infection outcomes with bacterial pathogens.

genetics↗