Intestinal IgA Regulates Expression of a Fructan Polysaccharide Utilization Locus in Colonizing Gut Commensal Bacteroides thetaiotaomicron

ABSTRACT Gut-derived immunoglobulin A (IgA) is the most abundant antibody secreted in the gut that shapes gut microbiota composition and functionality. However, most of the microbial antigens targeted by gut IgA remain unknown, and the functional effects of IgA targeting these antigens are currently understudied. This study provides a framework for identifying and characterizing gut microbiota antigens targeted by gut IgA. We developed a small intestinal ex vivo culture assay to harvest lamina propria IgA from gnotobiotic mice, with the aim of identifying antigenic targets in a model human gut commensal, Bacteroides thetaiotaomicron VPI-5482. Colonization by B. thetaiotaomicron induced a microbe-specific IgA response that was reactive against diverse antigens, including capsular polysaccharides, lipopolysaccharides, and proteins. IgA against microbial protein antigens targeted membrane and secreted proteins with diverse functionalities, including an IgA specific against proteins of the polysaccharide utilization locus (PUL) that are necessary for utilization of fructan, which is an important dietary polysaccharide. Further analyses demonstrated that the presence of dietary fructan increased the production of fructan PUL-specific IgA, which then downregulated the expression of fructan PUL in B. thetaiotaomicron, both in vivo and in vitro. Since the expression of fructan PUL has been associated with the ability of B. thetaiotaomicron to colonize the gut in the presence of dietary fructans, our work suggests a novel role for gut IgA in regulating microbial colonization by modulating their metabolism. IMPORTANCE Given the significant impact that gut microbes have on our health, it is essential to identify key host and environmental factors that shape this diverse community. While many studies have highlighted the impact of diet on gut microbiota, little is known about how the host regulates this critical diet-microbiota interaction. In our present study, we discovered that gut IgA targeted a protein complex involved in the utilization of an important dietary polysaccharide: fructan. While the presence of dietary fructans was previously thought to allow unrestricted growth of fructan-utilizing bacteria, our work shows that gut IgA, by targeting proteins responsible for fructan utilization, provides the host with tools that can restrict the microbial utilization of such polysaccharides, thereby controlling their growth.

Download Full-text

Metabolic Basis for Mutualism between Gut Bacteria and Its Impact on theDrosophila melanogasterHost

Applied and Environmental Microbiology ◽

10.1128/aem.01882-18 ◽

2018 ◽

Vol 85 (2) ◽

Cited By ~ 17

Author(s):

Andrew J. Sommer ◽

Peter D. Newell

Keyword(s):

Gut Microbiota ◽

Bacterial Species ◽

Waste Products ◽

Fermentation Products ◽

Content Type ◽

Starting Point ◽

Host Physiology ◽

The Impact

ABSTRACTInteractions between species shape the formation and function of microbial communities. In the gut microbiota of animals, cross-feeding of metabolites between microbes can enhance colonization and influence host physiology. We examined a mutually beneficial interaction between two bacteria isolated from the gut microbiota ofDrosophila, i.e.,Acetobacter fabarumandLactobacillus brevis. After developing anin vitrococulture assay, we utilized a genetic screen to identifyA. fabarumgenes required for enhanced growth withL. brevis. The screen, and subsequent genetic analyses, showed that the gene encoding pyruvate phosphate dikinase (ppdK) is required forA. fabarumto benefit fully from coculture. By testing strains with mutations in a range of metabolic genes, we provide evidence thatA. fabarumcan utilize multiple fermentation products ofL. brevis. Mutualism between the bacteriain vivoaffects gnotobioticDrosophila melanogaster; flies associated withA. fabarumandL. brevisshowed >1,000-fold increases in bacterial cell density and significantly lower triglyceride storage than monocolonized flies. Mutation ofppdKdecreasedA. fabarumdensity in flies cocolonized withL. brevis, consistent with the model in whichAcetobacteremploys gluconeogenesis to assimilateLactobacillusfermentation products as a source of carbonin vivo. We propose that cross-feeding between these groups is a common feature of microbiota inDrosophila.IMPORTANCEThe digestive tracts of animals are home to a community of microorganisms, the gut microbiota, which affects the growth, development, and health of the host. Interactions among microbes in this inner ecosystem can influence which species colonize the gut and can lead to changes in host physiology. We investigated a mutually beneficial interaction between two bacterial species from the gut microbiota of fruit flies. By coculturing the bacteriain vitro, we were able to identify a metabolic gene required for the bacteria to grow better together than they do separately. Our data suggest that one species consumes the waste products of the other, leading to greater productivity of the microbial community and modifying the nutrients available to the host. This study provides a starting point for investigating how these and other bacteria mutually benefit by sharing metabolites and for determining the impact of mutualism on host health.

Download Full-text

A Putative Type V Pilus Contributes toBacteroides thetaiotaomicronBiofilm Formation Capacity

Journal of Bacteriology ◽

10.1128/jb.00650-18 ◽

2019 ◽

Vol 201 (18) ◽

Cited By ~ 3

Author(s):

Jovana Mihajlovic ◽

Nathalie Bechon ◽

Christa Ivanova ◽

Florian Chain ◽

Alexandre Almeida ◽

...

Keyword(s):

Gut Microbiota ◽

Selection Procedure ◽

Bacteroides Thetaiotaomicron ◽

Human Gut ◽

Healthy Human ◽

Content Type ◽

Human Gut Microbiota ◽

Type V

ABSTRACTBacteroides thetaiotaomicronis a prominent anaerobic member of the healthy human gut microbiota. While the majority of functional studies onB. thetaiotaomicronaddressed its impact on the immune system and the utilization of diet polysaccharides,B. thetaiotaomicronbiofilm capacity and its contribution to intestinal colonization are still poorly characterized. We tested the natural adhesion of 34B. thetaiotaomicronisolates and showed that although biofilm capacity is widespread amongB. thetaiotaomicronstrains, this phenotype is masked or repressed in the widely used reference strain VPI 5482. Using transposon mutagenesis followed by a biofilm positive-selection procedure, we identified VPI 5482 mutants with increased biofilm capacity corresponding to an alteration in the C-terminal region of BT3147, encoded by theBT3148-BT3147locus, which displays homology with Mfa-like type V pili found in manyBacteroidetes. We show that BT3147 is exposed on theB. thetaiotaomicronsurface and that BT3147-dependent adhesion also requires BT3148, suggesting that BT3148 and BT3147 correspond to the anchor and stalk subunits of a new type V pilus involved inB. thetaiotaomicronadhesion. This study therefore introducesB. thetaiotaomicronas a model to study proteinaceous adhesins and biofilm-related phenotypes in this important intestinal symbiont.IMPORTANCEAlthough the gut anaerobeBacteroides thetaiotaomicronis a prominent member of the healthy human gut microbiota, little is known about its capacity to adhere to surfaces and form biofilms. Here, we identify that alteration of a surface-exposed protein corresponding to a type of pili found in manyBacteroidetesincreasesB. thetaiotaomicronbiofilm formation. This study lays the ground for establishing this bacterium as a model organism forin vitroandin vivostudies of biofilm-related phenotypes in gut anaerobes.

Download Full-text

Exogenous Alginate Protects Staphylococcus aureus from Killing by Pseudomonas aeruginosa

Journal of Bacteriology ◽

10.1128/jb.00559-19 ◽

2019 ◽

Vol 202 (8) ◽

Cited By ~ 2

Author(s):

Courtney E. Price ◽

Dustin G. Brown ◽

Dominique H. Limoli ◽

Vanessa V. Phelan ◽

George A. O’Toole

Keyword(s):

Staphylococcus Aureus ◽

Pseudomonas Aeruginosa ◽

Physical Space ◽

Late Time ◽

Protective Effects ◽

Content Type ◽

Alginate Production ◽

The Impact

ABSTRACT Cystic fibrosis (CF) patients chronically infected with both Pseudomonas aeruginosa and Staphylococcus aureus have worse health outcomes than patients who are monoinfected with either P. aeruginosa or S. aureus. We showed previously that mucoid strains of P. aeruginosa can coexist with S. aureus in vitro due to the transcriptional downregulation of several toxic exoproducts typically produced by P. aeruginosa, including siderophores, rhamnolipids, and HQNO (2-heptyl-4-hydroxyquinoline N-oxide). Here, we demonstrate that exogenous alginate protects S. aureus from P. aeruginosa in both planktonic and biofilm coculture models under a variety of nutritional conditions. S. aureus protection in the presence of exogenous alginate is due to the transcriptional downregulation of pvdA, a gene required for the production of the iron-scavenging siderophore pyoverdine as well as the downregulation of the PQS (Pseudomonas quinolone signal) (2-heptyl-3,4-dihydroxyquinoline) quorum sensing system. The impact of exogenous alginate is independent of endogenous alginate production. We further demonstrate that coculture of mucoid P. aeruginosa with nonmucoid P. aeruginosa strains can mitigate the killing of S. aureus by the nonmucoid strain of P. aeruginosa, indicating that the mechanism that we describe here may function in vivo in the context of mixed infections. Finally, we investigated a panel of mucoid clinical isolates that retain the ability to kill S. aureus at late time points and show that each strain has a unique expression profile, indicating that mucoid isolates can overcome the S. aureus-protective effects of mucoidy in a strain-specific manner. IMPORTANCE CF patients are chronically infected by polymicrobial communities. The two dominant bacterial pathogens that infect the lungs of CF patients are P. aeruginosa and S. aureus, with ∼30% of patients coinfected by both species. Such coinfected individuals have worse outcomes than monoinfected patients, and both species persist within the same physical space. A variety of host and environmental factors have been demonstrated to promote P. aeruginosa-S. aureus coexistence, despite evidence that P. aeruginosa kills S. aureus when these organisms are cocultured in vitro. Thus, a better understanding of P. aeruginosa-S. aureus interactions, particularly mechanisms by which these microorganisms are able to coexist in proximal physical space, will lead to better-informed treatments for chronic polymicrobial infections.

Download Full-text

Ellagitannins, Gallotannins and their Metabolites- The Contribution to the Anti-Inflammatory Effect of Food Products and Medicinal Plants

Current Medicinal Chemistry ◽

10.2174/0929867323666160919111559 ◽

2019 ◽

Vol 25 (37) ◽

pp. 4946-4967 ◽

Cited By ~ 18

Author(s):

Anna K. Kiss ◽

Jakub P. Piwowarski

Keyword(s):

Immune Response ◽

Gastrointestinal Tract ◽

Gut Microbiota ◽

Health Effects ◽

Biological Effects ◽

Food Products ◽

Anti Inflammatory ◽

The Impact

The popularity of food products and medicinal plant materials containing hydrolysable tannins (HT) is nowadays rapidly increasing. Among various health effects attributable to the products of plant origin rich in gallotannins and/or ellagitannins the most often underlined is the beneficial influence on diseases possessing inflammatory background. Results of clinical, interventional and animal in vivo studies clearly indicate the antiinflammatory potential of HT-containing products, as well as pure ellagitannins and gallotannins. In recent years a great emphasis has been put on the consideration of metabolism and bioavailability of natural products during examination of their biological effects. Conducted in vivo and in vitro studies of polyphenols metabolism put a new light on this issue and indicate the gut microbiota to play a crucial role in the health effects following their oral administration. The aim of the review is to summarize the knowledge about HT-containing products’ phytochemistry and their anti-inflammatory effects together with discussion of the data about observed biological activities with regards to the current concepts on the HTs’ bioavailability and metabolism. Orally administered HT-containing products due to the limited bioavailability of ellagitannins and gallotannins can influence immune response at the level of gastrointestinal tract as well as express modulating effects on the gut microbiota composition. However, due to the chemical changes being a result of their transit through gastrointestinal tract, comprising of hydrolysis and gut microbiota metabolism, the activity of produced metabolites has to be taken into consideration. Studies regarding biological effects of the HTs’ metabolites, in particular urolithins, indicate their strong and structure-dependent anti-inflammatory activities, being observed at the concentrations, which fit the range of their established bioavailability. The impact of HTs on inflammatory processes has been well established on various in vivo and in vitro models, while influence of microbiota metabolites on silencing the immune response gives a new perspective on understanding anti-inflammatory effects attributed to HT containing products, especially their postulated effectiveness in inflammatory bowel diseases (IBD) and cardiovascular diseases.

Download Full-text

In VivoEfficacy of Anuran Trypsin Inhibitory Peptides against Staphylococcal Skin Infection and the Impact of Peptide Cyclization

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.04324-14 ◽

2015 ◽

Vol 59 (4) ◽

pp. 2113-2121 ◽

Cited By ~ 9

Author(s):

U. Malik ◽

O. N. Silva ◽

I. C. M. Fensterseifer ◽

L. Y. Chan ◽

R. J. Clark ◽

...

Keyword(s):

Antimicrobial Agents ◽

Cyclic Peptide ◽

Sequence Similarity ◽

Infection Model ◽

Content Type ◽

Wide Range ◽

Inhibitory Activities ◽

The Impact

ABSTRACTStaphylococcus aureusis a virulent pathogen that is responsible for a wide range of superficial and invasive infections. Its resistance to existing antimicrobial drugs is a global problem, and the development of novel antimicrobial agents is crucial. Antimicrobial peptides from natural resources offer potential as new treatments against staphylococcal infections. In the current study, we have examined the antimicrobial properties of peptides isolated from anuran skin secretions and cyclized synthetic analogues of these peptides. The structures of the peptides were elucidated by nuclear magnetic resonance (NMR) spectroscopy, revealing high structural and sequence similarity with each other and with sunflower trypsin inhibitor 1 (SFTI-1). SFTI-1 is an ultrastable cyclic peptide isolated from sunflower seeds that has subnanomolar trypsin inhibitory activity, and this scaffold offers pharmaceutically relevant characteristics. The five anuran peptides were nonhemolytic and noncytotoxic and had trypsin inhibitory activities similar to that of SFTI-1. They demonstrated weakin vitroinhibitory activities againstS. aureus, but several had strong antibacterial activities againstS. aureusin anin vivomurine wound infection model. pYR, an immunomodulatory peptide fromRana sevosa, was the most potent, with complete bacterial clearance at 3 mg · kg−1. Cyclization of the peptides improved their stability but was associated with a concomitant decrease in antimicrobial activity. In summary, these anuran peptides are promising as novel therapeutic agents for treating infections from a clinically resistant pathogen.

Download Full-text

Ex VivoMaturation Assay for Testing Antimalarial Sensitivity of Rodent Malaria Parasites

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.01292-16 ◽

2016 ◽

Vol 60 (11) ◽

pp. 6859-6866 ◽

Cited By ~ 4

Author(s):

Zi Wei Chang ◽

Benoit Malleret ◽

Bruce Russell ◽

Laurent Rénia ◽

Carla Claser

Keyword(s):

Ex Vivo ◽

Single Step ◽

Parasite Development ◽

Ring Stage ◽

Malaria Parasites ◽

Rodent Malaria ◽

Content Type ◽

Parasite Biology

ABSTRACTEx vivoassay systems provide a powerful approach to studying human malaria parasite biology and to testing antimalarials. For rodent malaria parasites, short-termin vitroculture andex vivoantimalarial susceptibility assays are relatively cumbersome, relying onin vivopassage for synchronization, since ring-stage parasites are an essential starting material. Here, we describe a new approach based on the enrichment of ring-stagePlasmodium berghei,P. yoelii, andP. vinckei vinckeiusing a single-step Percoll gradient. Importantly, we demonstrate that the enriched ring-stage parasites develop synchronously regardless of the parasite strain or species used. Using a flow cytometry assay with Hoechst and ethidium or MitoTracker dye, we show that parasite development is easily and rapidly monitored. Finally, we demonstrate that this approach can be used to screen antimalarial drugs.

Download Full-text

Microbial enzymes induce colitis by reactivating triclosan in the mouse gastrointestinal tract

Nature Communications ◽

10.1038/s41467-021-27762-y ◽

2022 ◽

Vol 13 (1) ◽

Author(s):

Jianan Zhang ◽

Morgan E. Walker ◽

Katherine Z. Sanidad ◽

Hongna Zhang ◽

Yanshan Liang ◽

...

Keyword(s):

Gut Microbiota ◽

Molecular Mechanisms ◽

Ex Vivo ◽

Metabolic Activation ◽

Consumer Products ◽

Environmental Chemicals ◽

Intestinal Microbes ◽

Targeted Inhibition

AbstractEmerging research supports that triclosan (TCS), an antimicrobial agent found in thousands of consumer products, exacerbates colitis and colitis-associated colorectal tumorigenesis in animal models. While the intestinal toxicities of TCS require the presence of gut microbiota, the molecular mechanisms involved have not been defined. Here we show that intestinal commensal microbes mediate metabolic activation of TCS in the colon and drive its gut toxicology. Using a range of in vitro, ex vivo, and in vivo approaches, we identify specific microbial β-glucuronidase (GUS) enzymes involved and pinpoint molecular motifs required to metabolically activate TCS in the gut. Finally, we show that targeted inhibition of bacterial GUS enzymes abolishes the colitis-promoting effects of TCS, supporting an essential role of specific microbial proteins in TCS toxicity. Together, our results define a mechanism by which intestinal microbes contribute to the metabolic activation and gut toxicity of TCS, and highlight the importance of considering the contributions of the gut microbiota in evaluating the toxic potential of environmental chemicals.

Download Full-text

In VitroandIn VivoActivities of Zinc Linolenate, a Selective Antibacterial Agent againstHelicobacter pylori

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00004-19 ◽

2019 ◽

Vol 63 (6) ◽

Cited By ~ 5

Author(s):

Yanqiang Huang ◽

Xudong Hang ◽

Xueqing Jiang ◽

Liping Zeng ◽

Jia Jia ◽

...

Keyword(s):

Gut Microbiota ◽

Therapeutic Potential ◽

Combined Therapy ◽

Peptic Ulcers ◽

Current Standard ◽

Gastric Diseases ◽

Content Type ◽

H Pylori

ABSTRACTHelicobacter pyloriis a major global pathogen, and its infection represents a key factor in the etiology of various gastric diseases, including gastritis, peptic ulcers, and gastric carcinoma. The efficacy of current standard treatment forH. pyloriinfection including two broad-spectrum antibiotics is compromised by toxicity toward the gut microbiota and the development of drug resistance, which will likely only be resolved through novel and selective antibacterial strategies. Here, we synthesized a small molecule, zinc linolenate (ZnLla), and investigated its therapeutic potential for the treatment ofH. pyloriinfection. ZnLla showed effective antibacterial activity against standard strains and drug-resistant clinical isolates ofH. pyloriin vitrowith no development of resistance during continuous serial passaging. The mechanisms of ZnLla action againstH. pyloriinvolved the disruption of bacterial cell membranes and generation of reactive oxygen species. In mouse models of multidrug-resistantH. pyloriinfection, ZnLla showedin vivokilling efficacy comparable and superior to the triple therapy approach when use as a monotherapy and a combined therapy with omeprazole, respectively. Moreover, ZnLla treatment induces negligible toxicity against normal tissues and causes minimal effects on both the diversity and composition of the murine gut microbiota. Thus, the high degree of selectivity of ZnLla forH. pyloriprovides an attractive candidate for novel targeted anti-H. pyloritreatment.

Download Full-text

EZH2 inhibition reduces cartilage loss and functional impairment related to osteoarthritis

Scientific Reports ◽

10.1038/s41598-020-76724-9 ◽

2020 ◽

Vol 10 (1) ◽

Author(s):

Lyess Allas ◽

Sybille Brochard ◽

Quitterie Rochoux ◽

Jules Ribet ◽

Cleo Dujarrier ◽

...

Keyword(s):

Functional Disability ◽

Ex Vivo ◽

Cartilage Degradation ◽

Motor Functions ◽

Methyl Transferase ◽

Expression Of Genes ◽

Medial Meniscectomy ◽

The Impact

Abstract Histone methyltransferase EZH2 is upregulated during osteoarthritis (OA), which is the most widespread rheumatic disease worldwide, and a leading cause of disability. This study aimed to assess the impact of EZH2 inhibition on cartilage degradation, inflammation and functional disability. In vitro, gain and loss of EZH2 function were performed in human articular OA chondrocytes stimulated with IL-1β. In vivo, the effects of EZH2 inhibition were investigated on medial meniscectomy (MMX) OA mouse model. The tissue alterations were assayed by histology and the functional disabilities of the mice by actimetry and running wheel. In vitro, EZH2 overexpression exacerbated the action of IL-1β in chondrocytes increasing the expression of genes involved in inflammation, pain (NO, PGE2, IL6, NGF) and catabolism (MMPs), whereas EZH2 inhibition by a pharmacological inhibitor, EPZ-6438, reduced IL-1β effects. Ex vivo, EZH2 inhibition decreased IL-1β-induced degradation of cartilage. In vivo, intra-articular injections of the EZH2 inhibitor reduced cartilage degradation and improved motor functions of OA mice. This study demonstrates that the pharmacological inhibition of the histone methyl-transferase EZH2 slows the progression of osteoarthritis and improves motor functions in an experimental OA model, suggesting that EZH2 could be an effective target for the treatment of OA by reducing catabolism, inflammation and pain.

Download Full-text

MR imaging of model drug distribution in simulated vitreous

Current Directions in Biomedical Engineering ◽

10.1515/cdbme-2015-0059 ◽

2015 ◽

Vol 1 (1) ◽

pp. 236-239 ◽

Cited By ~ 2

Author(s):

Sandra Stein ◽

Christian Simroth-Loch ◽

Sönke Langner ◽

Stefan Hadlich ◽

Oliver Stachs ◽

...

Keyword(s):

Molecular Weight ◽

Ex Vivo ◽

Drug Distribution ◽

Injection Technique ◽

Innovative Therapy ◽

Age Related ◽

The Impact

AbstractThe in vitro and in vivo characterization of intravitreal injections plays an important role in developing innovative therapy approaches. Using the established vitreous model (VM) and eye movement system (EyeMoS) the distribution of contrast agents with different molecular weight was studied in vitro. The impact of the simulated age-related vitreal liquefaction (VL) on drug distribution in VM was examined either with injection through the gel phase or through the liquid phase. For comparison the distribution was studied ex vivo in the porcine vitreous. The studies were performed in a magnetic resonance (MR) scanner. As expected, with increasing molecular weight the diffusion velocity and the visual distribution of the injected substances decreased. Similar drug distribution was observed in VM and in porcine eye. VL causes enhanced convective flow and faster distribution in VM. Confirming the importance of the injection technique in progress of VL, injection through gelatinous phase caused faster distribution into peripheral regions of the VM than following injection through liquefied phase. VM and MR scanner in combination present a new approach for the in vitro characterization of drug release and distribution of intravitreal dosage forms.

Download Full-text