Name: an intestinal gut organ culture system for analyzing host-microbiota interactions
Uploaded: 2021-06-30T15:00:00
Description: Watch this Scientific Journal Video about An Intestinal Gut Organ Culture System for Analyzing Host-Microbiota Interactions at JoVE.com

We thank past and present members of the Yissachar lab for their valuable contributions in optimizing the gut organ culture system protocol. We thank Yael Laure for critical editing of the manuscript. This work was supported by the Israel Science Foundation (grant No. 3114831), the Israel Science Foundation - Broad Institute Joint Program (grant No. 8165162), and the Gassner Fund for Medical Research, Israel.

This protocol follows the animal care guidelines approved by the ethics committee for animal welfare.
1. Experiment preparation
<ol>
	<li>Fabrication of the gut organ culture device (3 days)
	<ol>
		<li>Using a 3D printer, print the reusable plastic molds for the organ culture device (the device has 6 wells, with 24 small and large holes, and for the device cover lid) (3D files attached). 
		NOTE: These plastic molds may be used for fabrication of numerous devices.</li>
		<li>Insert the...

<ol>
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S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Harnessing+Colon+Chip+Technology+to+Identify+Commensal+Bacteria+That+Promote+Host+Tolerance+to+Infection.">Harnessing Colon Chip Technology to Identify Commensal Bacteria That Promote Host Tolerance to Infection.</a> Frontiers in Cellular and Infection Microbiology. 11, 638014 (2021).</li><li>Yissachar, N., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+Intestinal+Organ+Culture+System+Uncovers+a+Role+for+the+Nervous+System+in+Microbe-Immune+Crosstalk.">An Intestinal Organ Culture System Uncovers a Role for the Nervous System in Microbe-Immune Crosstalk.</a> Cell. 168 (6), 1135-1148 (2017).</li><li>Duscha, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Propionic+Acid+Shapes+the+Multiple+Sclerosis+Disease+Course+by+an+Immunomodulatory+Mechanism.">Propionic Acid Shapes the Multiple Sclerosis Disease Course by an Immunomodulatory Mechanism.</a> Cell. 180 (6), 1067-1080 (2020).</li><li>Grosheva, I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High-Throughput+Screen+Identifies+Host+and+Microbiota+Regulators+of+Intestinal+Barrier+Function.">High-Throughput Screen Identifies Host and Microbiota Regulators of Intestinal Barrier Function.</a> Gastroenterology. 159 (5), 1807-1823 (2020).</li><li>Blaize, J. F., Corbo, C. P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Serial+Dilutions+and+Plating:+Microbial+Enumeration.">Serial Dilutions and Plating: Microbial Enumeration.</a> Journal of Visualized Experiments. , (2021).</li><li>Ivanov, I. I., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Induction+of+intestinal+Th17+cells+by+segmented+filamentous+bacteria.">Induction of intestinal Th17 cells by segmented filamentous bacteria.</a> Cell. 139 (3), 485-498 (2009).</li><li>Schnupf, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Growth+and+host+interaction+of+mouse+segmented+filamentous+bacteria+in+vitro.">Growth and host interaction of mouse segmented filamentous bacteria in vitro.</a> Nature. 520 (7545), 99-103 (2015).</li><li>Chung, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Gut+immune+maturation+depends+on+colonization+with+a+host-specific+microbiota.">Gut immune maturation depends on colonization with a host-specific microbiota.</a> Cell. 149 (7), 1578-1593 (2012).</li><li>Atarashi, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Th17+Cell+Induction+by+Adhesion+of+Microbes+to+Intestinal+Epithelial+Cells.">Th17 Cell Induction by Adhesion of Microbes to Intestinal Epithelial Cells.</a> Cell. 163 (2), 367-380 (2015).</li></ol>

This article describe an optimized protocol for ex vivo gut organ cultures that Yissachar et al. have recently developed (published9 and unpublished data). The gut organ culture system supports multiplexed culture of intact intestinal fragments while maintaining luminal flow. It provides full control over the intra- and extra-luminal environment (including stimulation dose, exposure time and flow rate) and preserves the na&#239;ve intestinal tissue structure and its cellular complexity<su...

The intestine is a highly complex organ containing a wide range of cell types (epithelial cells, immune system cells, neurons, and more) organized in a particular structure that allows cells to interact and communicate with one another and with the luminal content (microbiota, food, etc.)1. Currently, the research toolbox available for analyzing host-microbiota interactions includes in vitro cell cultures and in vivo animal models2. In vivo animal models provide a physiological tissue construction3 but with poor experimental control and limited ability to manipulate the experiment conditions. In vitro culture systems, on the other hand, use primary cells or cell lines that can be supplemented with microbes4, offering tight control over the experiment parameters but lack the cellular complexity and the tissue architecture. Modern in vitro assays allow the advanced use of healthy and pathological human tissue samples, like epithelial organoids derived from mouse or human sources5,6, and samples that mimic the mucosal microenvironment7. Another example is the &#39;gut on a chip&#39; assay, which includes the human colonic epithelial cell line (Caco2), extracellular matrix and microfluidic channels to mimic the physiological condition of the gut invariant8. However, as advanced and innovative as in vitro samples may be, they do not maintain a normal tissue architecture or na&#239;ve cellular composition.
To address that, Yissachar et al. recently developed an ex vivo organ culture system9 (Figure 1)&#160;that maintains intact gut fragments ex vivo, benefiting from the advantages of both in vivo and in vitro models. This ex vivo gut organ culture system is based on a custom-made culture device that supports a multiplexed culture of six colon tissues, allowing examining experimental inputs under comparable conditions while controlling the system&#39;s inputs and outputs. Recent works have demonstrated that this system is valuable for analyzing intestinal responses to individual gut bacteria9, whole human microbiota samples10 and microbial metabolites11. This system allows, for the first time, the study of these early host-microbiota interactions with a high level of control over the host, microbial and environmental components. Furthermore, it allows monitoring and manipulating the system throughout the experiment, in real-time.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/62779/62779fig01.jpg" /> 
Figure 1: Schematics of the gut culture device. A whole intestinal tissue fragment is attached to the output and input ports of the chamber (top), with pumps regulating the medium flow inside the lumen and in the external medium chamber. The entire device (bottom) contains 6 such chambers. This figure has been modified from Yissachar et al. 2017. <a href="https://www.jove.com/files/ftp_upload/62779/62779fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

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			<td>HEPES Buffer (1M)</td>
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			<td>Iscove&#39;s Mod Dulbecco&#39;s Medium With Phenol Red (1x)</td>
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an intestinal gut organ culture system for analyzing host-microbiota interactions

The structure of the gut tissue facilitates close and mutualistic interactions between the host and the gut microbiota. These cross-talks are crucial for maintaining local and systemic homeostasis; changes to gut microbiota composition (dysbiosis) associate with a wide array of human diseases. Methods for dissecting host-microbiota interactions encompass an inherent tradeoff among preservation of physiological tissue structure (when using in vivo animal models) and the level of control over the experiment factors (as in simple in vitro cell culture systems). To address this tradeoff, Yissachar et al. recently developed an intestinal organ culture system. The system preserves a naive colon tissue construction and cellular mechanisms and it also permits tight experimental control, facilitating experimentations that cannot be readily performed in vivo. It is optimal for dissecting short-term responses of various gut components (such as epithelial, immunological and neuronal elements) to luminal perturbations (including anaerobic or aerobic microbes, whole microbiota samples from mice or humans, drugs and metabolites). Here, we present a detailed description of an optimized protocol for organ culture of multiple gut fragments using a custom-made gut culture device. Host responses to luminal perturbations can be visualized by immunofluorescence staining of tissue sections or whole-mount tissue fragments, fluorescence in-situ hybridization (FISH), or time-lapse imaging. This system supports a wide array of readouts, including next-generation sequencing, flow cytometry, and various cellular and biochemical assays. Overall, this three-dimensional organ culture system supports the culture of large, intact intestinal tissues and has broad applications for high-resolution analysis and visualization of host-microbiota interactions in the local gut environment.

The gut organ culture system maintains tissue viability ex vivo. The evaluation of the tissue viability was done throughout the culture period. Colon tissue fragments were incubated in the gut organ culture system and fixed following 2/12/24 h culture. The intestinal epithelial cell (IEC) layer integrity was validated by immunofluorescence staining using E-cadherin and cytokeratin-18 antibodies. Likewise, mucus-filled goblet cells in the colonic epithelium and mucus secretion within the lumen were detected as we...

Watch this Scientific Journal Video about An Intestinal Gut Organ Culture System for Analyzing Host-Microbiota Interactions at JoVE.com

An Intestinal Gut Organ Culture System for Analyzing Host-Microbiota Interactions

This article presents a unique method for analyzing host-microbiome interactions using a novel gut organ culture system for ex vivo experiments.

The structure of the gut tissue facilitates close and mutualistic interactions between the host and the gut microbiota. These cross-talks are crucial for ...

The gut organ culture system combines the advantages of in vitro and in vivo assays and thus serves as an intermediate experimental step between simple in vitro assays to complex in vivo experiments. The main advantage of this technique is the combination of tight experimental control with the preservation of intestinal physiology. This method provides insight for analyzing intestinal responses to specific stimulus with high level of control over the host, microbial, and the environmental components.Demonstrating the procedure will be Alon Shemesh, a Masters student from my laboratory, and Dr.Sivan Amidror, our lab manager. To begin, insert the blunt-end needles to the appropriate position within the device mold and cast approximately 20 grams of polydimethylsiloxane or PDMS mix, for one set of the device and lid. Place the molds in a vacuum chamber for 30 minutes to remove air bubbles from the PDMS mix, then incubate the molds at 55 degrees Celsius overnight to complete PDMS polymerization.When the PDMS is set, pull out the needles from the mold and carefully release the culture device and lid from the plastic molds. Remove PDMS residues from the well outline using a surgical blade. Attach the PDMS device and the device cover onto a cover glass of 75 by 50 millimeter microslides using non-toxic silicon adhesive and leave the parts to set overnight.Apply the glued to the smooth side of the device. Insert 12, 22 gauge needles for the lumen and 12, 18 gauge needles for the well. Fix all the needles in place using silicone and let it set overnight.Purge the input syringes and make sure that the well medium flows out from all tubes into a waste glass, then purge the input syringes and makes sure that the stimulations flow out of all the tubes into a waste glass, taking care to not contaminate the different stimulations. After sacrificing the mouse, use sharp scissors and forceps to dissect it and take out the digestive tract from the stomach to the anus, by cutting all the fat and connective tissues. Cut the colon and place it on a new plate.Minimize contact while holding the tissue gently and only at the edges. Perform the colon flush under a dissection microscope. Gently flush the colon content with sterile IMDM with the prepared 10 milliliter syringe as described in the text.After removing the feces from the intestinal tissue, place the colon in a new six well plate filled with 0.5 milliliters of sterile IMDM. Next, take the colon tissue and carefully connect it to the 22 gauge needle, making a tight tie with the two threads. Maintain the correct orientation of the colon to the lumen flow, such that the proximal and distal is equal to input and output, respectively.Repeat colon flushing and needle tying for all the tissues. Connect the input and output tubes to the device, then begin the experiment by starting the pumps at the desired rates. Mucus-filled goblet cells in the colonic epithelium and mucus secretion within the lumen were detected as well as proliferating IEC in the colonic crypts, as indicated by KI67 staining.These results showed that the gut culture system maintains intestinal function and structure ex-vivo. After two hours of segmented filamentous bacteria, or SFB, introduction, typical SFB filaments were detected in close association with small intestine villi using fluorescence in situ hybridization. Additionally, a transmission electron microscopy presented SFB within a few microns of the small intestine epithelium brush border.Gene expression profiles of whole tissue samples were produced in triplicate two hours after infusion with SFB. Control cultures were infused with fecal suspensions of germ-free or Bacteroides fragilis monocolonized mice. These changes persuaded by SFB were mainly of small amplitude compared to the germ-free control.The orientation of the colon is highly important. Take extra care when tying the colon on the needle. Proper tie will prevent the contamination of the well with the lumen content.A wide range of readout techniques can follow this protocol, such as next generation sequencing, imaging, cell sorting, and many more. This readouts provide novel insight into host microbiome interactions in health and disease.

an-intestinal-gut-organ-culture-system-for-analyzing-host-microbiota

Research

JoVE Journal

Immunology and Infection

Use of an Optical Trap for Study of Host-Pathogen Interactions for Dynamic Live Cell Imaging

Dynamic live cell imaging allows direct visualization of real-time interactions between cells of the immune system1, 2; however, the lack of spatial and temporal control between the phagocytic cell and microbe has rendered focused observations into the initial interactions of host response to pathogens difficult. Historically, intercellular contact events such as phagocytosis3 have been imaged by mixing two cell types, and then continuously scanning the field-of-view to find serendipitous intercellular contacts at the appropriate stage of interaction. The stochastic nature of these events renders this process tedious, and it is difficult to observe early or fleeting events in cell-cell contact by this approach. This method requires finding cell pairs that are on the verge of contact, and observing them until they consummate their contact, or do not. To address these limitations, we use optical trapping as a non-invasive, non-destructive, but fast and effective method to position cells in culture.
Optical traps, or optical tweezers, are increasingly utilized in biological research to capture and physically manipulate cells and other micron-sized particles in three dimensions4. Radiation pressure was first observed and applied to optical tweezer systems in 19705, 6, and was first used to control biological specimens in 19877. Since then, optical tweezers have matured into a technology to probe a variety of biological phenomena8-13.
We describe a method14 that advances live cell imaging by integrating an optical trap with spinning disk confocal microscopy with temperature and humidity control to provide exquisite spatial and temporal control of pathogenic organisms in a physiological environment to facilitate interactions with host cells, as determined by the operator. Live, pathogenic organisms like Candida albicans and Aspergillus fumigatus, which can cause potentially lethal, invasive infections in immunocompromised individuals15, 16 (e.g. AIDS, chemotherapy, and organ transplantation patients), were optically trapped using non-destructive laser intensities and moved adjacent to macrophages, which can phagocytose the pathogen. High resolution, transmitted light and fluorescence-based movies established the ability to observe early events of phagocytosis in living cells. To demonstrate the broad applicability in immunology, primary T-cells were also trapped and manipulated to form synapses with anti-CD3 coated microspheres in vivo, and time-lapse imaging of synapse formation was also obtained. By providing a method to exert fine spatial control of live pathogens with respect to immune cells, cellular interactions can be captured by fluorescence microscopy with minimal perturbation to cells and can yield powerful insight into early responses of innate and adaptive immunity.

A method is described to individually select, manipulate, and image live pathogens using an optical trap coupled to a spinning disk microscope. The optical trap provides spatial and temporal control of organisms and places them adjacent to host cells. Fluorescence microscopy captures dynamic intercellular interactions with minimal perturbation to cells.

Dynamic live cell imaging allows direct visualization of real-time interactions between cells of the immune system1, 2; however, the lack of spatial and ...

The Ex Vivo Culture and Pattern Recognition Receptor Stimulation of Mouse Intestinal Organoids

Primary intestinal organoids are a valuable model system that has the potential to significantly impact the field of mucosal immunology. However, the complexities of the organoid growth characteristics carry significant caveats for the investigator. Specifically, the growth patterns of each individual organoid are highly variable and create a heterogeneous population of epithelial cells in culture. With such caveats, common tissue culture practices cannot be simply applied to the organoid system due to the complexity of the cellular structure. Counting and plating based solely on cell number, which is common for individually separated cells, such as cell lines, is not a reliable method for organoids unless some normalization technique is applied. Normalizing to total protein content is made complex due to the resident protein matrix. These characteristics in terms of cell number, shape and cell type should be taken into consideration when evaluating secreted contents from the organoid mass. This protocol has been generated to outline a simple procedure to culture and treat small intestinal organoids with microbial pathogens and pathogen associated molecular patterns (PAMPs). It also emphasizes the normalization techniques that should be applied when protein analysis are conducted after such a challenge.

The Ex Vivo Culture and Pattern Recognition Receptor Stimulation of Mouse Intestinal Organoids

Here, a protocol to harvest, maintain, and treat mouse small intestinal organoids with pathogen associated molecular patterns (PAMPs) and Listeria monocytogenes is described, as well as emphasis on gene expression and proper normalization techniques for protein.

Primary intestinal organoids are a valuable model system that has the potential to significantly impact the field of mucosal immunology. However, the ...

Establishment of a High-throughput Setup for Screening Small Molecules That Modulate c-di-GMP Signaling in Pseudomonas aeruginosa

Bacterial resistance to traditional antibiotics has driven research attempts to identify new drug targets in recently discovered regulatory pathways. Regulatory systems that utilize intracellular cyclic di-GMP (c-di-GMP) as a second messenger are one such class of target. c-di-GMP is a signaling molecule found in almost all bacteria that acts to regulate an extensive range of processes including antibiotic resistance, biofilm formation and virulence. The understanding of how c-di-GMP signaling controls aspects of antibiotic resistant biofilm development has suggested approaches whereby alteration of the cellular concentrations of the nucleotide or disruption of these signaling pathways may lead to reduced biofilm formation or increased susceptibility of the biofilms to antibiotics. We describe a simple high-throughput bioreporter protocol, based on green fluorescent protein (GFP), whose expression is under the control of the c-di-GMP responsive promoter cdrA, to rapidly screen for small molecules with the potential to modulate c-di-GMP cellular levels in Pseudomonas aeruginosa (P. aeruginosa). This simple protocol can screen upwards of 3,500 compounds within 48 hours and has the ability to be adapted to multiple microorganisms.

Establishment of a High-throughput Setup for Screening Small Molecules That Modulate c-di-GMP Signaling in Pseudomonas aeruginosa

This article describes the high-throughput assay that has been successfully established to screen large libraries of small molecules for their potential ability to manipulate cellular levels of cyclic di-GMP in Pseudomonas aeruginosa, providing a new powerful tool for antibacterial drug discovery and compound testing.

Bacterial resistance to traditional antibiotics has driven research attempts to identify new drug targets in recently discovered regulatory pathways. ...

The Ex Vivo Colon Organ Culture and Its Use in Antimicrobial Host Defense Studies

The intestine displays an architecture of repetitive crypt structures consisting of different types of epithelial cells, lamina propia containing immune cells, and stroma. All of these heterogeneous cells contribute to intestinal homeostasis and participate in antimicrobial host defense. Therefore, identifying a surrogate model for studying immune response and antimicrobial activity of the intestine in an in vitro setting is extremely challenging. In vitro studies using immortalized intestinal epithelial cell lines or even primary crypt organoid culture do not represent the exact physiology of normal intestine and its microenvironment. Here, we discuss a method of culturing mouse colon tissue in a culture dish and how this ex vivo organ culture system can be implemented in studies related to antimicrobial host defense responses. In representative experiments, we showed that colons in organ culture express antimicrobial peptides in response to exogenous IL-1&#946; and IL-18. Further, the antimicrobial effector molecules produced by the colon tissues in the organ culture efficiently kill Escherichia coli in vitro. This approach, therefore, can be utilized to dissect the role of pathogen- and danger-associated molecular patterns and their cellular receptors in regulating intestinal innate immune responses and antimicrobial host defense responses.

The Ex Vivo Colon Organ Culture and Its Use in Antimicrobial Host Defense Studies

The ex vivo organ culture allows investigation of biological processes in the context of the intact tissue architecture. Here, we introduce a method of ex vivo culture of the mouse colon, which can be used to study innate immunity and antimicrobial host defense in the intestine.

The intestine displays an architecture of repetitive crypt structures consisting of different types of epithelial cells, lamina propia containing immune ...

Isolating Lymphocytes from the Mouse Small Intestinal Immune System

The intestinal immune system plays an essential role in maintaining the barrier function of the gastrointestinal tract by generating tolerant responses to dietary antigens and commensal bacteria while mounting effective immune responses to enteropathogenic microbes. In addition, it has become clear that local intestinal immunity has a profound impact on distant and systemic immunity. Therefore, it is important to study how an intestinal immune response is induced and what the immunologic outcome of the response is. Here, a detailed protocol is described for the isolation of lymphocytes from small intestine inductive sites like the gut-associated lymphoid tissue Peyer&#39;s patches and the draining mesenteric lymph nodes and effector sites like the lamina propria and the intestinal epithelium. This technique ensures isolation of a large numbers of lymphocytes from small intestinal tissues with optimal purity and viability and minimal cross compartmental contamination within acceptable time constraints. The technical capability to isolate lymphocytes and other immune cells from intestinal tissues enables the understanding of immune responses to gastrointestinal infections, cancers, and inflammatory diseases.

Here we describe a detailed protocol for the isolation of lymphocytes from the inductive sites including the gut-associated lymphoid tissue Peyer&#39;s patches and the draining mesenteric lymph nodes, and the effector sites including the lamina propria and the intestinal epithelium of the small intestinal immune system.

The intestinal immune system plays an essential role in maintaining the barrier function of the gastrointestinal tract by generating tolerant responses to ...

Human Colonoid Monolayers to Study Interactions Between Pathogens, Commensals, and Host Intestinal Epithelium

Human 3-dimensional (3D) enteroid or colonoid cultures derived from crypt base stem cells are currently the most advanced ex vivo model of the intestinal epithelium. Due to their closed structures and significant supporting extracellular matrix, 3D cultures are not ideal for host-pathogen studies. Enteroids or colonoids can be grown as epithelial monolayers on permeable tissue culture membranes to allow manipulation of both luminal and basolateral cell surfaces and accompanying fluids. This enhanced luminal surface accessibility facilitates modeling bacterial-host epithelial interactions such as the mucus-degrading ability of enterohemorrhagic E. coli (EHEC) on colonic epithelium. A method for 3D culture fragmentation, monolayer seeding, and transepithelial electrical resistance (TER) measurements to monitor the progress towards confluency and differentiation are described. Colonoid monolayer differentiation yields secreted mucus that can be studied by the immunofluorescence or immunoblotting techniques. More generally, enteroid or colonoid monolayers enable a physiologically-relevant platform to evaluate specific cell populations that may be targeted by pathogenic or commensal microbiota.

Here, we present a protocol to culture human enteroid or colonoid monolayers that have intact barrier function to study host epithelial-microbiota interactions at the cellular and biochemical level.

Human 3-dimensional (3D) enteroid or colonoid cultures derived from crypt base stem cells are currently the most advanced ex vivo model of the intestinal ...

Analysis of Interactions between Endobiotics and Human Gut Microbiota Using In Vitro Bath Fermentation Systems

Human intestinal microorganisms have recently become an important target of research in promoting human health and preventing diseases. Consequently, investigations of interactions between endobiotics (e.g., drugs and prebiotics) and gut microbiota have become an important research topic. However, in vivo experiments with human volunteers are not ideal for such studies due to bioethics and economic constraints. As a result, animal models have been used to evaluate these interactions in vivo. Nevertheless, animal model studies are still limited by bioethics considerations, in addition to differing compositions and diversities of microbiota in animals vs. humans. An alternative research strategy is the use of batch fermentation experiments that allow evaluation of the interactions between endobiotics and gut microbiota in vitro. To evaluate this strategy, bifidobacterial (Bif) exopolysaccharides (EPS) were used as a representative xenobiotic. Then, the interactions between Bif EPS and human gut microbiota were investigated using several methods such as thin-layer chromatography (TLC), bacterial community compositional analysis with 16S rRNA gene high-throughput sequencing, and gas chromatography of short-chain fatty acids (SCFAs). Presented here is a protocol to investigate the interactions between endobiotics and human gut microbiota using in vitro batch fermentation systems. Importantly, this protocol can also be modified to investigate general interactions between other endobiotics and gut microbiota.

Described here is a protocol to investigate the interactions between endobiotics and human gut microbiota using in vitro batch fermentation systems.

Human intestinal microorganisms have recently become an important target of research in promoting human health and preventing diseases. Consequently, ...

High Throughput Co-culture Assays for the Investigation of Microbial Interactions

The study of interactions between microorganisms has led to numerous discoveries, from novel antimicrobials to insights in microbial ecology. Many approaches used for the study of microbial interactions require specialized equipment and are expensive and time intensive. This paper presents a protocol for co-culture interaction assays that are inexpensive, scalable to large sample numbers, and easily adaptable to numerous experimental designs. Microorganisms are cultured together, with each well representing one pairwise combination of microorganisms. A test organism is cultured on one side of each well and first incubated in monoculture. Subsequently, target organisms are simultaneously inoculated onto the opposite side of each well using a 3D-printed inoculation stamp. After co-culture, the completed assays are scored for visual phenotypes, such as growth or inhibition. These assays can be used to confirm phenotypes or identify patterns among isolates of interest. Using this simple and effective method, users can analyze combinations of microorganisms rapidly and efficiently. This co-culture approach is applicable to antibiotic discovery as well as culture-based microbiome research and has already been successfully applied to both applications.

The co-culture interaction assays presented in this protocol are inexpensive, high throughput, and simple. These assays can be used to observe microbial interactions in co-culture, identify interaction patterns, and characterize the inhibitory potential of a microbial strain of interest against human and environmental pathogens.

The study of interactions between microorganisms has led to numerous discoveries, from novel antimicrobials to insights in microbial ecology. Many ...

Optimization of the Cuff Technique for Murine Heart Transplantation

Murine cardiac transplantation has been performed for more than 40 years. With advancements in microsurgery, certain new techniques have been used to improve surgical efficiency. In our lab, we have optimized the cuff technique with two major steps. First, we used the inner tube technique to insert a temporary inner tube into the external jugular vein and carotid artery blood vessel to facilitate eversion of the vessel over the cuff. Second, we performed complete heterotopic cardiac transplantation through the collaboration of two experienced surgeons. These modifications effectively reduced the operation time to 25 minutes, with a success rate of 95%. In this report, we describe these procedures in detail and provide a supplemental video. We believe that this report on the improved cuff technique will offer practical guidance for murine heterotopic heart transplantation and will enhance the utility of this mouse model for basic research.

We introduce an inner tube approach to the cuff technique for mouse cervical heterotopic heart transplantation to help evert the vessel over the cuff. We found that cooperation between two experienced surgeons markedly shortens the operation time.

Murine cardiac transplantation has been performed for more than 40 years. With advancements in microsurgery, certain new techniques have been used to ...

Visualization of Gut Microbiota-host Interactions via Fluorescence In Situ Hybridization, Lectin Staining, and Imaging

Measuring the localization of microbes within their in vivo context is an essential step in revealing the functional relationships between the microbiota and the vertebrate gut. The spatial landscape of the gut microbiota is tightly controlled by physical features - intestinal mucus, crypts, and folds - and is affected by host-controlled properties such as pH, oxygen availability, and immune factors. These properties limit the ability of commensal microbes and pathogens alike to colonize the gut stably. At the micron-scale, microbial organization determines the close-range interactions between different microbes as well as the interactions between microbes and their host. These interactions then affect large-scale organ function and host health.
This protocol enables the visualization of the gut microbiota spatial organization from distances between cells to organ-wide scales. The method is based on fixing gut tissues while preserving intestinal structure and mucus properties. The fixed samples are then embedded, sectioned, and stained to highlight specific bacterial species through fluorescence in situ hybridization (FISH). Host features, such as mucus and host cell components, are labeled with fluorescently labeled lectins. Finally, the stained sections are imaged using a confocal microscope utilizing tile-scan imaging at high magnification to bridge the micron to centimeter length scales. This type of imaging can be applied to intestinal sections from animal models and biopsies from human tissues to determine the biogeography of the microbiota in the gut in health and disease.

Visualization of Gut Microbiota-host Interactions via Fluorescence In Situ Hybridization, Lectin Staining, and Imaging

This streamlined protocol details a workflow to detect and image bacteria in complex tissue samples, from fixing the tissue to staining microbes with fluorescent in situ hybridization.

Measuring the localization of microbes within their in vivo context is an essential step in revealing the functional relationships between the microbiota ...