Detection of colorectal dysplasia using fluorescently labelled lectins

Dissecting Gut-Microbial Community Interactions using a Gut Microbiome-on-a-Chip

While the human gut microbiota has a significant impact on gut health and disease, understanding of the roles of gut microbes, interactions, and collective impact of gut microbes on various aspects of human gut health is limited by the lack of suitable in vitro model system that can accurately replicate gut-like environment and enable the close visualization on causal and mechanistic relationships between microbial constitutents and the gut. , In this study, we present a scalable Gut Microbiome-on-a-Chip (GMoC) with great imaging capability and scalability, providing a physiologically relevant dynamic gut-microbes interfaces. This chip features a reproducible 3D stratified gut epithelium derived from Caco-2 cells (µGut), mimicking key intestinal architecture, functions, and cellular complexity, providing a physiolocially relevant gut environment for microbes residing in the gut. Incorporating tumorigenic bacteria, enterotoxigenic Bacteroides fragilis (ETBF), into the GMoC enable the observation of pathogenic behaviors of ETBF, leading to µGut disruption and pro-tumorigenic signaling activations. Pre-treating the µGut with a beneficial gut microbe Lactobacillus spp., effectively prevent ETBF-mediated gut pathogenesis, preserving the healthy state of the µGut through competition-mediated colonization resistance. The GMoC holds potential as a valuable tool for exploring unknown roles of gut microbes in microbe-induced pathogenesis and microbe-based therapeutic development.

Quality assessment of variable collagen tissues of sea cucumber (Stichopus japonicus) body wall under different heat treatment durations by label-Free proteomics analysis

The microstructure of the body wall, body wall composition, and collagen fibers of sea cucumber (Stichopus japonicus) under different heating times (1 h, 4 h, 12 h, and 24 h) was investigated based on heat treatment at 80 °C. A Label-Free proteomics technique was applied to study the proteomic changes in the body wall of sea cucumbers under 4 and 12 h of heat treatment. Compared with the fresh group, 981 proteins were found to be differentially expressed proteins (DEPs) after heat treatment at 80 °C (4 h), and 1110 DEPs were observed after heat treatment at the same temperature for 12 h. There were 69 DEPs associated with mutable collagenous tissues (MCTs) structures. The results of correlation analysis showed that 55 DEPs were correlated with sensory properties, among which A0A2G8KRV2 was significantly correlated with hardness and SEM image texture features (SEM_Energy, SEM_Correlation, SEM_Homogeneity, and SEM_Contrast). These findings could be conducive to further comprehension of the structural changes and mechanisms of quality loss in the body wall of sea cucumbers at different heat treatment times.

Exploring Effects of Chitosan Oligosaccharides on the DSS-Induced Intestinal Barrier Impairment In Vitro and In Vivo

Intestinal barrier dysfunction is an essential pathological change in inflammatory bowel disease (IBD). The mucus layer and the intestinal epithelial tight junction act together to maintain barrier integrity. Studies showed that chitosan oligosaccharide (COS) had a positive effect on gut health, effectively protecting the intestinal barrier in IBD. However, these studies usually focused on its impact on the intestinal epithelial tight junction. The influence of COS on the intestinal mucus layer is still poorly understood. In this study, we explored the effect of COS on intestinal mucus in vitro using human colonic mucus-secreted HT-29 cells. COS relieved DSS (dextran sulfate sodium)-induced mucus defects. Additionally, the structural characteristics of COS greatly influenced this activity. Finally, we evaluated the protective effect of COS on intestinal barrier function in mice with DSS-induced colitis. The results indicated that COS could manipulate intestinal mucus production, which likely contributed to its intestinal protective effects.

The Role of Fecal Fusobacterium nucleatum and pks+ Escherichia coli as Early Diagnostic Markers of Colorectal Cancer

BACKGROUND

Accurate analysis of intestinal microbiota will facilitate establishment of an evaluating system for assessing colorectal cancer (CRC) risk and prognosis. This study evaluates the potential role of Fusobacterium nucleatum (F. nucleatum) and Escherichia coli with a pks gene (pks⁺ E. coli) in early CRC diagnosis.

METHODS

We recruited 139 patients, including CRC (n = 60), colorectal adenomatous polyposis (CAP) (n = 37), and healthy individuals (n = 42) based on their colonoscopy examinations. We collected stool and serum samples from the participants and measured the relative abundance of F. nucleatum and pks⁺ E. coli in fecal samples by quantitative PCR. Receiver operating characteristic curve (ROC) analyses were used to analyze the diagnostic value of single or combined biomarkers.

RESULTS

Fecal F. nucleatum and pks⁺ E. coli levels were higher in the CRC group in either the CAP group or healthy controls (P = 0.02; 0.01). There was no statistical difference in the distribution of F. nucleatum and pks⁺ E. coli in patients with different tumor sites (P > 0.05). The combination of F. nucleatum+pks⁺ E. coli+CEA+CA19-9+FOBT was chosen as the optimal panel in differentiating both CRC and CAP from the controls. The combination of F. nucleatum, pks⁺ E. coli, and FOBT improved diagnostic efficiency. However, there was difficulty in differentiating CRC from CAP.

CONCLUSION

Our results suggested that combining bacterial markers with conventional tumor markers improves the diagnostic efficiency for noninvasive diagnosis of CRC.

Chemopreventive effect of α-hederin/carboplatin combination against experimental colon hyperplasia and impact on JNK signaling

Colon cancer is the commonest cancer worldwide. α-Hederin is a monodesmosidic triterpenoid saponin possessing diverse pharmacological activities. The running experiment was designed to test the chemopreventive activity of α-hederin when used as an adjuvant to carboplatin in an experimental model of mouse colon hyperplasia induced by 1,2-dimethylhydrazine (DMH). Fifty male Swiss albino mice were classified into five groups: group (I): saline group, group (II): DMH-induced colon hyperplasia control group, group (III): DMH + carboplatin (5 mg/kg) group, group (IV): DMH + α-hederin (80 mg/kg) group, and group (V): DMH + carboplatin (5 mg/kg)+α-hederin (80 mg/kg) group. Analyzing of colonic tissue indicated that the disease control group showed higher colon levels of phospho-PI3K to total-PI3K, phospho-AKT to total-AKT and cyclin D1 concurrent with lower phospho-JNK/total JNK ratio and caspase 3. However, treatment with α-hederin, in combination with carboplatin, favorably ameliorated phosphorylation of PI3K/AKT/JNK proteins, increased colon caspase 3 and downregulated cyclin D1. Microscopically, α-hederin, in combination with carboplatin, produced the most reduction in the histologic hyperplasia score, enhanced the goblet cell survival in periodic acid Schiff staining and reduced proliferation (Ki-67 immunostaining) in the current colon hyperplasia model. Collectively, the current study highlighted for the first time that using α-hederin as an adjuvant to carboplatin enhanced its chemopreventive activity, improved JNK signaling and increased apoptosis. Hence, further studies are warranted to test α-hederin as a promising candidate with chemotherapeutic agents in treating colon cancer.

Lectins in Cervical Screening

Cervical screening in low-resource settings remains an unmet need. Lectins are naturally occurring sugar-binding glycoproteins whose binding patterns change as cancer develops. Lectins discriminate between dysplasia and normal tissue in several precancerous conditions. We explored whether lectins could be developed for cervical screening via visual inspection. Discovery work comprised lectin histochemistry using a panel of candidate lectins on fixed-human cervix tissue (high-grade cervical intraepithelial neoplasia (CIN3, n = 20) or normal (n = 20)), followed by validation in a separate cohort (30 normal, 25 CIN1, 25 CIN3). Lectin binding was assessed visually according to staining intensity. To validate findings macroscopically, near-infra red fluorescence imaging was conducted on freshly-resected cervix (1 normal, 7 CIN3), incubated with topically applied fluorescently-labelled lectin. Fluorescence signal was compared for biopsies and whole specimens according to regions of interest, identified by the overlay of histopathology grids. Lectin histochemistry identified two lectins-wheat germ agglutinin (WGA) and Helix pomatia agglutinin (HPA)-with significantly decreased binding to CIN3 versus normal in both discovery and validation cohorts. Findings at the macroscopic level confirmed weaker WGA binding (lower signal intensity) in CIN3 vs. normal for biopsies (p = 0.0308) and within whole specimens (p = 0.0312). Our findings confirm proof-of-principle and indicate that WGA could potentially be developed further as a probe for high-grade cervical disease.

H-type lectins - Structural characteristics and their applications in diagnostics, analytics and drug delivery

Lectins are ubiquitous carbohydrate-binding proteins that interact with sugar moieties in a highly specific manner. H-type lectins represent a new group of lectins that were identified in invertebrates. These lectins share structural homology and bind mainly to N-acetylgalactosamine (GalNAc). Recent structural studies on the H-type lectins provided a detailed description of the GalNAc-lectin interaction that is already exploited in a number of biomedical applications. Two members of the H-type lectin family, Helix pomatia agglutinin (HPA) and Helix aspersa agglutinin (HAA), have already been extensively used in many diagnostic tests due their ability to specifically recognize GalNAc. This ability is especially important because aberrant glycosylation patterns of proteins expressed by cancer cells contain GalNAc. In addition, H-type lectins were utilized in diagnostics of other non-cancer diseases and represent great potential as components of drug delivery systems. Here, we present an overview of the H-type lectins and their applications in diagnostics, analytics and drug delivery.

Recapitulation of the accessible interface of biopsy-derived canine intestinal organoids to study epithelial-luminal interactions

Recent advances in canine intestinal organoids have expanded the option for building a better in vitro model to investigate translational science of intestinal physiology and pathology between humans and animals. However, the three-dimensional geometry and the enclosed lumen of canine intestinal organoids considerably hinder the access to the apical side of epithelium for investigating the nutrient and drug absorption, host-microbiome crosstalk, and pharmaceutical toxicity testing. Thus, the creation of a polarized epithelial interface accessible from apical or basolateral side is critical. Here, we demonstrated the generation of an intestinal epithelial monolayer using canine biopsy-derived colonic organoids (colonoids). We optimized the culture condition to form an intact monolayer of the canine colonic epithelium on a nanoporous membrane insert using the canine colonoids over 14 days. Transmission and scanning electron microscopy revealed a physiological brush border interface covered by the microvilli with glycocalyx, as well as the presence of mucin granules, tight junctions, and desmosomes. The population of stem cells as well as differentiated lineage-dependent epithelial cells were verified by immunofluorescence staining and RNA in situ hybridization. The polarized expression of P-glycoprotein efflux pump was confirmed at the apical membrane. Also, the epithelial monolayer formed tight- and adherence-junctional barrier within 4 days, where the transepithelial electrical resistance and apparent permeability were inversely correlated. Hence, we verified the stable creation, maintenance, differentiation, and physiological function of a canine intestinal epithelial barrier, which can be useful for pharmaceutical and biomedical researches.

Sticking to the Problem: Engineering Adhesion in Molecular Endoscopic Imaging

Cancers of the digestive tract cause nearly one quarter of the cancer deaths worldwide, and nearly half of these are due to cancers of the esophagus and colon. Early detection of cancer significantly increases the rate of survival, and thus it is critical that cancer within these organs is detected early. In this regard, endoscopy is routinely used to screen for transforming/cancerous (i.e. dysplastic to fully cancerous) tissue. Numerous studies have revealed that the biochemistry of the luminal surface of such tissue within the colon and esophagus becomes altered throughout disease progression. Molecular endoscopic imaging (MEI), an emerging technology, seeks to exploit these changes for the early detection of cancer. The general approach for MEI is as follows: the luminal surface of an organ is exposed to molecular ligands, or particulate probes bearing a ligand, cognate to biochemistry unique to pre-cancerous/cancerous tissue. After a wash, the tissue is imaged to determine the presence of the probes. Detection of the probes post-washing suggests pathologic tissue. In the current review we provide a succinct, but extensive, review of ligands and target moieties that could be, or are currently being investigated, as possible cognate chemistries for MEI. This is followed by a review of the biophysics that determines, in large part, the success of a particular MEI design. The work draws an analogy between MEI and the well-advanced field of cell adhesion and provides a road map for engineering MEI to achieve assays that yield highly selective recognition of transforming/cancerous tissue in situ.

Microscopy examination of red blood and yeast cell agglutination induced by bacterial lectins

Lectins are a group of ubiquitous proteins which specifically recognize and reversibly bind sugar moieties of glycoprotein and glycolipid constituents on cell surfaces. The mutagenesis approach is often employed to characterize lectin binding properties. As lectins are not enzymes, it is not easy to perform a rapid specificity screening of mutants using chromogenic substrates. It is necessary to use different binding assays such as isothermal titration calorimetry (ITC), surface plasmon resonance (SPR), microscale thermophoresis (MST), enzyme-linked lectin assays (ELLA), or glycan arrays for their characterization. These methods often require fluorescently labeled proteins (MST), highly purified proteins (SPR) or high protein concentrations (ITC). Mutant proteins may often exhibit problematic behaviour, such as poor solubility or low stability. Lectin-based cell agglutination is a simple and low-cost technique which can overcome most of these problems. In this work, a modified method of the agglutination of human erythrocytes and yeast cells with microscopy detection was successfully used for a specificity study of the newly prepared mutant lectin RS-IIL_A22S, which experimentally completed studies on sugar preferences of lectins in the PA-IIL family. Results showed that the sensitivity of this method is comparable with ITC, is able to determine subtle differences in lectin specificity, and works directly in cell lysates. The agglutination method with microscopy detection was validated by comparison of the results with results obtained by agglutination assay in standard 96-well microtiter plate format. In contrast to this assay, the microscopic method can clearly distinguish between hemagglutination and hemolysis. Therefore, this method is suitable for examination of lectins with known hemolytic activity as well as mutant or uncharacterized lectins, which could damage red blood cells. This is due to the experimental arrangement, which includes very short sample incubation time in combination with microscopic detection of agglutinates, that are easily observed by a small portable microscope.

A complex human gut microbiome cultured in an anaerobic intestine-on-a-chip

The diverse bacterial populations that comprise the commensal microbiome of the human intestine play a central role in health and disease. A method that sustains complex microbial communities in direct contact with living human intestinal cells and their overlying mucus layer in vitro would thus enable investigations of host–microbiome interactions. Here, we show the extended co-culture of living human intestinal epithelium with stable communities of aerobic and anaerobic human gut microbiota, enabled by a microfluidic intestine-on-a-chip that permits the control and real-time assessment of physiologically relevant oxygen gradients. When compared to aerobic co-culture conditions, the establishment of a transluminal hypoxia gradient in the chip increased intestinal barrier function and sustained a physiologically relevant level of microbial diversity, consisting of over 200 unique operational taxonomic units from 11 different genera, and of an abundance of obligate anaerobic bacteria with ratios of Firmicutes and Bacteroidetes similar to those observed in human faeces. The intestine-on-a-chip may serve as a discovery tool for the development of microbiome-related therapeutics, probiotics and nutraceuticals.

Evaluation of a Lectin-Based Imaging System for the Chairside Detection of Oral Dysplasia and Malignancy

PURPOSE

Currently available oral cancer screening adjuncts have not enhanced clinical screening methods because of high false positives and negatives, highlighting the need for a molecularly specific technique for accurate screening of suspicious oral lesions. The purpose of this study was to evaluate the in vivo screening accuracy of an oral lesion identification system that evaluates aberrant glycosylation patterns using a fluorescently labeled lectin (wheat germ agglutinin and fluorescein isothiocyanate [WGA-FITC]).

MATERIALS AND METHODS

The authors designed and implemented a prospective cohort study at 3 institutions composed of patients with and without suspicious oral lesions. Oral cavities were screened by clinical examination and with the oral lesion identification system according to a stepwise procedure that included the topical application and fluorescence visualization of a fluorescent nuclear stain and WGA-FITC. Tissue samples were obtained from all enrolled patients for histopathological diagnosis and were used to calculate sensitivity and specificity metrics (primary outcome variable) irrespective of the oral lesion identification system result.

RESULTS

The sample was composed of 97 patients; 86 had 100 clinically suspicious lesions and 11 without such lesions were included as a control group. Use of the oral lesion identification system resulted in 100, 100, and 74% sensitivity for cancer, high-grade dysplasia, and low-grade dysplasia, respectively, and a specificity of 80%. Clinical diagnosis yielded similar sensitivity values of 84, 100, and 88% for cancer, high-grade dysplasia, and low-grade dysplasia, respectively, and a specificity of 76%. Use of the oral lesion identification system enhanced the visualization of lesion dimensionality and borders.

CONCLUSIONS

The results of this study suggest the oral lesion identification system was a beneficial adjunct to standard clinical examination, because the system provided sensitivity and specificity values similar to or greater than clinical diagnosis.

A new approach for analyzing an adhesive bacterial protein in the mouse gastrointestinal tract using optical tissue clearing

Several bacterial moonlighting proteins act as adhesion factors, which are important for bacterial colonization of the gastrointestinal (GI) tract. However, little is known about the adherence properties of moonlighting proteins in the GI tract. Here, we describe a new approach for visualizing the localization of moonlighting protein-coated fluorescent microbeads in the whole GI tract by using a tissue optical clearing method, using elongation factor Tu (EF-Tu) as an example. As a bacterial cell surface-localized protein mimic, recombinant EF-Tu from Lactobacillus reuteri was immobilized on microbeads. EF-Tu-coating promoted the interaction of the microbeads with a Caco-2 cell monolayer. Next, the microbeads were orally administered to mice. GI whole tissues were cleared in aqueous fructose solutions of increasing concentrations. At 1 h after administration, the microbeads were diffused from the stomach up to the cecum, and after 3 h, they were diffused throughout the intestinal tract. In the lower digestive tract, EF-Tu-beads were significantly more abundant than non-coated control beads, suggesting that EF-Tu plays an important role in the persistence of the microbeads in the GI tract. The new approach will help in evaluating how moonlighting proteins mediate bacterial colonization.

Intestinal barrier dysfunction orchestrates the onset of inflammatory host-microbiome cross-talk in a human gut inflammation-on-a-chip

The initiation of intestinal inflammation involves complex intercellular cross-talk of inflammatory cells, including the epithelial and immune cells, and the gut microbiome. This multicellular complexity has hampered the identification of the trigger that orchestrates the onset of intestinal inflammation. To identify the initiator of inflammatory host-microbiome cross-talk, we leveraged a pathomimetic "gut inflammation-on-a-chip" undergoing physiological flow and motions that recapitulates the pathophysiology of dextran sodium sulfate (DSS)-induced inflammation in murine models. DSS treatment significantly impaired, without cytotoxic damage, epithelial barrier integrity, villous microarchitecture, and mucus production, which were rapidly recovered after cessation of DSS treatment. We found that the direct contact of DSS-sensitized epithelium and immune cells elevates oxidative stress, in which the luminal microbial stimulation elicited the production of inflammatory cytokines and immune cell recruitment. In contrast, an intact intestinal barrier successfully suppressed oxidative stress and inflammatory cytokine production against the physiological level of lipopolysaccharide or nonpathogenic Escherichia coli in the presence of immune elements. Probiotic treatment effectively reduced the oxidative stress, but it failed to ameliorate the epithelial barrier dysfunction and proinflammatory response when the probiotic administration happened after the DSS-induced barrier disruption. Maintenance of epithelial barrier function was necessary and sufficient to control the physiological oxidative stress and proinflammatory cascades, suggesting that "good fences make good neighbors." Thus, the modular gut inflammation-on-a-chip identifies the mechanistic contribution of barrier dysfunction mediated by intercellular host-microbiome cross-talk to the onset of intestinal inflammation.

Targeted Optical Imaging Agents in Cancer: Focus on Clinical Applications

Molecular imaging is an emerging strategy for in vivo visualization of cancer over time based on biological mechanisms of disease activity. Optical imaging methods offer a number of advantages for real-time cancer detection, particularly in the epithelium of hollow organs and ducts, by using a broad spectral range of light that spans from visible to near-infrared. Targeted ligands are being developed for improved molecular specificity. These platforms include small molecule, peptide, affibody, activatable probes, lectin, and antibody. Fluorescence labeling is used to provide high image contrast. This emerging methodology is clinically useful for early cancer detection by identifying and localizing suspicious lesions that may not otherwise be seen and serves as a guide for tissue biopsy and surgical resection. Visualizing molecular expression patterns may also be useful to determine the best choice of therapy and to monitor efficacy. A number of these imaging agents are overcoming key challenges for clinical translation and are being validated in vivo for a wide range of human cancers.

Detection of early neoplasia in Barrett's esophagus using lectin-based near-infrared imaging: an ex vivo study on human tissue

BACKGROUND AND STUDY AIMS

Endoscopic surveillance for Barrett's esophagus (BE) is limited by long procedure times and sampling error. Near-infrared (NIR) fluorescence imaging minimizes tissue autofluorescence and optical scattering. We assessed the feasibility of a topically applied NIR dye-labeled lectin for the detection of early neoplasia in BE in an ex vivo setting.

METHODS

Consecutive patients undergoing endoscopic mucosal resection (EMR) for BE-related early neoplasia were recruited. Freshly collected EMR specimens were sprayed at the bedside with fluorescent lectin and then imaged. Punch biopsies were collected from each EMR under NIR light guidance. We compared the fluorescence intensity from dysplastic and nondysplastic areas within EMRs and from punch biopsies with different histological grades.

RESULTS

29 EMR specimens were included from 17 patients. A significantly lower fluorescence was found for dysplastic regions across whole EMR specimens (P < 0.001). We found a 41 % reduction in the fluorescence of dysplastic compared to nondysplastic punch biopsies (P < 0.001), with a sensitivity and specificity for dysplasia detection of 80 % and 82.9 %, respectively.

CONCLUSION

Lectin-based NIR imaging can differentiate dysplastic from nondysplastic Barrett's mucosa ex vivo.

Fluorescence contrast-enhanced proliferative lesion imaging by enema administration of indocyanine green in a rat model of colon carcinogenesis

The fluorescent contrast agent indocyanine green (ICG) is approved by the Food and Drug Administration for clinical applications. We previously reported that cultured human colon tumor cells preferentially take up ICG by endocytic activity in association with disruption of their tight junctions. The present study explored ICG availability in fluorescence imaging of the colon to identify proliferative lesions during colonoscopy. The cellular uptake of ICG in cultured rat colon tumor cells was examined using live-cell imaging. Colon lesions in rats administered an ICG-containing enema were further assessed in rats with azoxymethane-induced colon carcinogenesis, using in vivo endoscopy, ex vivo microscopy, and immunofluorescence microscopy. The uptake of ICG by the cultured cells was temperature-dependent. The intracellular retention of the dye in the membrane trafficking system suggested endocytosis as the uptake mechanism. ICG administered via enema accumulated in colon proliferative lesions ranging from tiny aberrant crypt foci to adenomas and localized in proliferating cells. Fluorescence endoscopy detected these ICG-positive colonic proliferative lesions in vivo. The immunoreactivity of the tight-junction molecule occludin was altered in the proliferative lesions, suggesting the disruption of the integrity of tight junctions. These results suggest that fluorescence contrast-enhanced imaging following the administration of an ICG-containing enema can enhance the detection of mucosal proliferative lesions of the colon during colonoscopy. The tissue preference of ICG in the rat model evaluated in this study can be attributed to the disruption of tight junctions, which in turn promotes endocytosis by proliferative cells and the cellular uptake of ICG.