Human Intestine Research Articles

Akkermansia muciniphila inhibited the periodontitis caused by Fusobacterium nucleatum

Periodontitis is the most important cause of tooth loss in adults and is closely related to various systemic diseases. Its etiologic factor is plaque biofilm, and the primary treatment modality is plaque control. Studies have confirmed that Fusobacterium nucleatum can cause periodontitis through its virulence factors and copolymerizing effects with other periodontal pathogens, such as the red complex. Inhibiting F. nucleatum is an essential target for preventing periodontitis. The time-consuming and costly traditional periodontal treatment, periodontal scaling, and root planing are a significant burden on individual and public health. Antibiotic use may lead to oral microbial resistance and microbiome imbalance, while probiotics regulate microbial balance. Akkermansia muciniphila is a critical probiotic isolated from the human intestine. It can protect the integrity of the epithelial barrier, regulate and maintain flora homeostasis, improve metabolism, and colonize the oral cavity. Its abundance is inversely correlated with various diseases. We hypothesized that A. muciniphila could inhibit the effects of F. nucleatum and alleviate periodontitis. Bacterial co-culture experiments showed that A. muciniphila could inhibit the expression of the virulence gene of F. nucleatum. After treating gingival epithelial cells (GECs) with F. nucleatum and A. muciniphila, transcriptome sequencing and ELISA experiments on medium supernatant showed that A. muciniphila inhibited the inflammatory effect of F. nucleatum on GECs by inhibiting TLR/MyD88/NF-κB pathway modulation and secretion of inflammatory factors. Finally, animal experiments demonstrated that A. muciniphila could inhibit F. nucleatum-induced periodontitis in BALB/c mice.

The Mechanism of Antimicrobial Activity of Conjugated Bile Acids against Lactic Acid Bacilli.

The mechanism underlying antimicrobial activity of conjugated bile acids against strains of lactic acid bacilli is not well understood. The purpose of this study was to investigate two typical conjugated bile acids (glycochenodeoxycholic acid and taurochenodeoxycholic acid) for their mechanisms of antimicrobial activity against four strains of different species of lactic acid bacilli at the physiological pH of the small intestine of humans. The bacterial cell membrane integrity, transmembrane potential, and transmembrane pH gradient were examined using the fluorescence probes SYTO 9 plus propidium iodide, 3,3'-dipropylthiadicarbocyanine iodide, and 5(6)-carboxyfluorescein diacetate N-succinimidyl ester, respectively. The intracellular ATP levels were measured by the firefly luciferase-based bioluminescence method. It was found that the antimicrobial activity of conjugated bile acids against the strains of lactic acid bacilli is strain-specific, and glycochenodeoxycholic acid showed significantly greater antimicrobial activity than taurochenodeoxycholic acid against the strains of lactic acid bacilli. The conjugated bile acids inhibited the growth of strains of lactic acid bacilli by disrupting membrane integrity, dissipating transmembrane potential, reducing the transmembrane pH gradient, and depleting intracellular ATP. In conclusion, the antimicrobial activity of conjugated bile acids against lactic acid bacilli is a multifactorial phenomenon. This study will provide valuable information for developing strategies to improve the ability of lactic acid bacilli to tolerate bile in vivo.

Exploring the use of modified in vitro digestion assays for the evaluation of ritonavir loaded solid lipid-based formulations

Solid lipid-based formulations (sLBFs) have the potential to increase the oral bioavailability of drugs with poor solubility in water, while counteracting some of the disadvantages of liquid LBFs. The most common experimental set-up to study the performance of LBFs in vitro is the lipolysis assay, during which the LBFs are digested by lipases in an environment mimicking the human small intestine. However, this assay has failed in many cases to correctly predict the performance of LBFs in vivo, highlighting the need for new and improved in vitro assays to evaluate LBFs at the preclinical stage. In this study, the suitability of three different in vitro digestion assays for the evaluation of sLBFs was assessed; the classic one-step intestinal digestion assay, a two-step gastrointestinal digestion assay and a bicompartmental assay permitting the simultaneous monitoring of digestion and permeation of the active pharmaceutical ingredient (API) across an artificial membrane (Lecithin in Dodecane – LiDo). Three sLBFs (M1-M3) with varied composition and ritonavir as model drug were prepared and examined. When comparing the ability of these formulations to keep the drug solubilized in the aqueous phase, all three assays show that M1 performs better, while M3 presents poor performance. However, the classic in vitro intestinal digestion assay fails to provide a clear ranking of the three formulations, something that is more evident when using the two modified and more physiologically relevant assays. Also, the two modified assays provide additional information about the performance of the formulations including the performance in the gastric environment and intestinal flux of the drug. These modified in vitro digestion assays are valuable tools for the development and evaluation of sLBFs to make better informed decisions of which formulations to pursue for in vivo studies.

The gut-retina axis: a new perspective in the prevention and treatment of diabetic retinopathy.

Diabetic retinopathy (DR) is a microvascular lesion that occurs as a complication of diabetes mellitus. Many studies reveal that retinal neurodegeneration occurs early in its pathogenesis, and abnormal retinal function can occur in patients without any signs of microvascular abnormalities. The gut microbiota is a large, diverse colony of microorganisms that colonize the human intestine. Studies indicated that the gut microbiota is involved in the pathophysiological processes of DR and plays an important role in its development. On the one hand, numerous studies demonstrated the involvement of gut microbiota in retinal neurodegeneration. On the other hand, alterations in gut bacteria in RD patients can cause or exacerbate DR. The present review aims to underline the critical relationship between gut microbiota and DR. After a brief overview of the composition, function, and essential role of the gut microbiota in ocular health, and the review explores the concept of the gut-retina axis and the conditions of the gut-retina axis crosstalk. Because gut dysbiosis has been associated with DR, the review intends to determine changes in the gut microbiome in DR, the hypothesized mechanisms linking to the gut-retina axis, and its predictive potential.

The selenoprotein P-LRP5/6-WNT3A complex promotes tumorigenesis in sporadic colorectal cancer.

Some studies suggest that the trace element selenium protects against colorectal cancer (CRC). However, the contribution of selenoprotein P (SELENOP), a unique selenocysteine-containing protein, to sporadic colorectal carcinogenesis challenges this paradigm. SELENOP is predominately secreted by the liver but is also expressed in various cells of the small intestine and colon in mice and humans. In this issue of the JCI, Pilat et al. demonstrate that increased SELENOP expression promoted the progression of conventional adenomas to carcinoma. SELENOP functioned as a modulator of canonical WNT signaling activity through interactions with WNT3A and its coreceptor LDL receptor-related protein 5/6 (LRP5/6). Secreted SELENOP formed a concentration gradient along the gut crypt axis, which might amplify WNT signaling activity by binding to LRPL5/6. The mechanism for WNT control via SELENOP may affect colorectal tumorigenesis and provide therapeutic targets for CRC.

Evaluation of the Antimicrobial Activity of Bacteriocin-Producing Lactic Acid Bacteria Isolated from Human Intestine against Pathogenic Microorganisms

Evaluation of the Antimicrobial Activity of Bacteriocin-Producing Lactic Acid Bacteria Isolated from Human Intestine against Pathogenic Microorganisms

Eating our way to gut microbiome characterization

A recent study in Nature introduced an innovative ingestible device capable of collecting in situ samplesfrom different regions of the human intestine for multi-omics analysis. This groundbreaking technology enables non-invasive and longitudinal characterization of the gut microbiome and associated metabolites.

Evaluation of Different Control Strategies for Trajectory Following of a Robotic Capsule Endoscope Under Rotating Magnetic Actuation

Current wireless capsule endoscopy (WCE) is limited in the long examination time and low flexibility since the capsule is passively moved by the natural peristalsis. Efforts have been made to facilitate active locomotion of WCE using magnetic actuation and localization technologies. In this work, we investigate the trajectory following problem of a robotic capsule under rotating magnetic actuation, in order to realize efficient and accurate navigation of the capsule in the narrow, complex intestinal environments. Specifically, four control strategies are developed based on the PD controller, adaptive controller (AC), model predictive controller (MPC) and robust multi-stage model predictive controller (RMMPC). In particular, the RMMPC method takes into account the uncertainty in the intestinal environment by modeling the intestinal peristalsis and friction in the controller design. We evaluate the proposed methods in simulation as well as in real-world experiments in several tubular environments, including plastic phantoms with complex shapes and an ex-vivo pig colon. The results have demonstrated the potential of the proposed control methods to realize accurate and efficient inspection of the intestine using active WCE. Our methods can be integrated with current WCE to improve the diagnostic accuracy and efficiency of the GI tract. <i>Note to Practitioners</i>&#x2014;The motivation of this paper is to solve the trajectory following problem for active WCE in the human intestine to realize accurate, efficient and repeatable inspection of the gastrointestinal (GI) tract. We present four different control strategies for 5-DOF control of a robotic capsule endoscope actuated by a reciprocally rotating permanent magnet to make the capsule follow a predefined trajectory in a tubular environment. The accuracy and efficiency of the approach are validated in simulation and real-world experiments. The proposed trajectory following strategies can be integrated into existing WCE products to allow automatic and repeatable examination of the GI tract, and can also be extended to the locomotion of other tethered or untethered magnetic devices in the tubular environments for different medical and industrial applications. In the future, our proposed approach is expected to be combined with image-based automatic diagnosis of the GI tract to provide doctors with better tools for digestive examinations.

Late Microaerobic Growth for Efficient Production of Human Cytochrome P450 3A4 in E. coli.

Detailed preclinical characterization of metabolites formed in vivo from candidate drug substances is mandatory prior to the initiation of clinical trials. Therefore, inexpensive and efficient methods for drug metabolite synthesis are of high importance for rapid advancement of the drug development process. A large fraction of small molecule drugs is modified by monooxygenase cytochrome P450 3A4 produced in the human liver and intestine. Therefore, this enzyme is frequently employed to catalyze metabolite synthesis in vitro, making 3A4 availability a critical requirement in early drug development. Unfortunately, the recombinant production of this enzyme in microbial hosts is notoriously difficult. Maintaining low oxygen transfer rates and the use of rich media for host cultivation are required for P450 3A4 production. However, detailed studies on the relationship between oxygen supply and P450 3A4 space-time yields are missing. We describe an improved biotechnological process for the heterologous expression of P450 3A4 together with its redox partner, cytochrome P450 reductase, in Escherichia coli. Enzyme production was most efficient under so-called "late microaerobic" growth conditions, in which the cells have just not yet made the switch to anaerobic metabolism, characterized by a limited oxygen supply leading to oxygen concentrations in the liquid phase that are far below the detection limit of standard oxygen electrodes. Furthermore, feeding the carbon source glycerol as well as controlling cellular acetate formation improved process productivity. The presented protocol resulted in the formation of functional recombinant 3A4 at concentrations up to 680nmol L-1.

48: Luminal Preservation of the Human Intestine with a Polyethylene Glycol Solution Applicable for Transplantation.

48: Luminal Preservation of the Human Intestine with a Polyethylene Glycol Solution Applicable for Transplantation.

Composition of the colon microbiota in the individuals with inflammatory bowel disease and colon cancer.

The human intestine is a habitat for microorganisms and, recently, the composition of the intestinal microbiota has been correlated with the etiology of diseases such as inflammations, sores, and tumors. Although many studies have been conducted to understand the composition of that microbiota, expanding these studies to more samples and different backgrounds will improve our knowledge. In this work, we showed the colon microbiota composition and diversity of healthy subjects, patients with inflammatory bowel disease (IBD), and colon cancer by metagenomic sequencing. Our results indicated that the relative abundance of prokaryotic and eukaryotic microbes differs between the healthy vs. tumor biopsies, tumor vs. IBD biopsies, and fresh vs. paraffin-embedded tumor biopsies. Fusobacterium, Escherichia-Shigella, and Streptococcus genera were relatively abundant in fresh tumor biopsies, while Pseudomonas was significantly elevated in IBD biopsies. Additionally, another opportunist pathogen Malasseziales was revealed as the most abundant fungal clade in IBD biopsies, especially in ulcerative colitis. We also found that, while the Basidiomycota:Ascomycota ratio was slightly lower in tumor biopsies compared to biopsies from healthy subjects, there was a significant increase in IBD biopsies. Our work will contribute to the known diversity of prokaryotic and eukaryotic microbes in the colon biopsies in patients with IBD and colon cancer.

Increased Production of Interleukin-10 and Decreased Production of Tumor Necrosis Factor-α by Lacticaseibacillus rhamnosus PL60

Lacticaseibacillus rhamnosus PL60, originally isolated from healthy baby feces, has beneficial activities including resistance to acid and bile acids, immune-enhancing activity, inhibition of various intestinal pathogens, anti-oxidation activity, adherence to the intestines, susceptibility to antimicrobials, an anti-obesity effect, and an anti-fatty liver effect. In the present study, the binding activity of L. rhamnosus PL60 to the HT-29 human colorectal adenocarcinoma cell line and mouse intestines was established. L. rhamnosus PL60 increased interleukin-10 production and decreased tumor necrosis factor-α production in a dose-dependent manner in HT-29 cells treated with lipopolysaccharide. Similar results were observed in an in vivo experiment with BALB/c mice fed with L. rhamnosus PL60. Taken together, results from previous studies and the present study establish that L. rhamnosus PL60 is a probiotic candidate for inflammation-related diseases.

Blood-borne extracellular vesicles of bacteria and intestinal cells in patients with psychotic disorders

Background Human cells and bacteria secrete extracellular vesicles (EV) which play a role in intercellular communication. EV from the host intestinal epithelium are involved in the regulation of bacterial gene expression and growth. Bacterial EV (bactEV) produced in the intestine can pass to various tissues where they deliver biomolecules to many kinds of cells, including neurons. Emerging data indicate that gut microbiota is altered in patients with psychotic disorders. We hypothesized that the amount and content of blood-borne EV from intestinal cells and bactEV in psychotic patients would differ from healthy controls. Methods We analyzed for human intestinal proteins by proteomics, for bactEV by metaproteomic analysis, and by measuring the level of lipopolysaccharide (LPS) in blood-borne EV from patients with psychotic disorders (n = 25), tested twice, in the acute phase of psychosis and after improvement, with age- and sex-matched healthy controls (n = 25). Results Patients with psychotic disorders had lower LPS levels in their EV compared to healthy controls (p = .027). Metaproteome analyses confirmed LPS finding and identified Firmicutes and Bacteroidetes as dominating phyla. Total amounts of human intestine proteins in EV isolated from blood was lower in patients compared to controls (p = .02). Conclusions Our results suggest that bactEV and host intestinal EV are decreased in patients with psychosis and that this topic is worthy of further investigation given potential pathophysiological implications. Possible mechanisms involve dysregulation of the gut microbiota by host EV, altered translocation of bactEV to systemic circulation where bactEV can interact with both the brain and the immune system.

Essential Amino Acid Metabolites as Chemical Mediators of Host-Microbe Interaction in the Gut.

Amino acids are indispensable substrates for protein synthesis in all organisms and incorporated into diverse aspects of metabolic physiology and signaling. However, animals lack the ability to synthesize several of them and must acquire these essential amino acids from their diet or perhaps their associated microbial communities. The essential amino acids therefore occupy a unique position in the health of animals and their relationships with microbes. Here we review recent work connecting microbial production and metabolism of essential amino acids to host biology, and the reciprocal impacts of host metabolism of essential amino acids on their associated microbes. We focus on the roles of the branched-chain amino acids (valine, leucine, and isoleucine) and tryptophan on host-microbe communication in the intestine of humans and other vertebrates. We then conclude by highlighting research questions surrounding the less-understood aspects of microbial essential amino acid synthesis in animal hosts.

Assessments of the effects of tris(1,3-dichloro-2-propyl) phosphate (TDCPP) on human intestinal health from the aspects of intestinal flora changes and cytotoxicity to human cells

Organophosphorus flame retardants (OPFRs) are now drawing the public's attention due to their potential toxicity. Given that contaminated food may result in the ingestion of OPFRs to the human intestine, further investigation is required to determine the potential adverse effects of these compounds on human intestinal health. The present study aimed to comprehensively assess the effect of tris(1,3-dichloro-2-propyl) phosphate (TDCPP), a typical OPFR, on human intestinal health by evaluating both intestinal flora and human cell Caco-2. Based on the results, TDCPP exposure altered the composition of intestinal flora and increased the proportion of pathogenic bacteria. PICRUSt2 analysis revealed that certain pathways were affected by TDCPP, and the resulting metabolic disorders might cause health problems. Orthologous genes of glutathione S-transferase and multidrug efflux system were up-regulated, demonstrating that the bacteria resisted TDCPP to maintain their vitality. Compared to the other two OPFRs, TDCPP induced greater cytotoxicity, and the results were consistent with the dose-effect relationship. Three OPFRs, especially TDCPP, caused the release of lactate dehydrogenase, accumulation of ROS, decline in mitochondrial membrane potential and increase in intracellular Ca2+, which could consequently induce cell death. The simultaneous effects of TDCPP on both intestinal cells and intestinal flora are likely to engender more severe intestinal health issues.

PENENTUAN DISOLUSI PADA OBAT SENYAWA KETOPROFEN SECARA SPEKTROFOTOMETRI

Research on dissolution determination of Ketoprofen compounds by Spectrophotometry. Ketoprofen is a non-steroidal anti-inflammatory drug compound (NSAID) that works as an anti-inflammatory. Anti-inflammatory here is a group of drugs used to reduce inflammation and relieve pain. The dissolution test is a method used to determine the content of active compounds that dissolve in drugs, where the time, temperature and media are set according to the human stomach and intestines, and can find out how much the content of active compounds dissolves in the human intestines and stomach. This dissolution test, then the ketoprofen drug is read by spectrophotometry. Test the dissolution by spectrophotometer at a wavelength of 260 nm using HCl 0.1 N and buffer pH 7.4. The results of the determination of the dissolution test of the active substance on ketoprofen at the acid stage obtained an average of 0.009% and at the pH 7.4 buffer stage obtained an average content of 86.4155%. It can be concluded that the determination of the ketoprofen dissolution test in the sample meets the requirements (MS), in accordance with the specifications of the Internal Standard of PT Novell Pharmaceutical Laboratories, namely at the acid stage not more than 10% of ketoprofen dissolved in 2 hours, and at the pH 7.4 buffer stage it has a requirement of 75%. ketoprofen dissolved in 45 minutes. In the dissolution of acidic media, 0.1 N HCl is used because its condition resembles that of the stomach.

The gut-liver axis and gut microbiota in health and liver disease.

The trillions of microorganisms in the human intestine are important regulators of health, and disruptions in the gut microbial communities can cause disease. The gut, liver and immune system have a symbiotic relationship with these microorganisms. Environmental factors, such as high-fat diets and alcohol consumption, can disrupt and alter microbial communities. This dysbiosis can lead to dysfunction of the intestinal barrier, translocation of microbial components to the liver and development or progression of liver disease. Changes in metabolites produced by gut microorganisms can also contribute to liver disease. In this Review, we discuss the importance of the gut microbiota in maintenance of health and the alterations in microbial mediators that contribute to liver disease. We present strategies for modulation of the intestinal microbiota and/or their metabolites as potential treatments for liver disease.

High accuracy prediction of dipeptide angiotensin-converting enzyme (ACE) inhibitory activity by improving the credibility of the 3D-quantitative structure-activity relationship (3D-QSAR) model database and investigating inhibition mechanism

The 3D-QSAR model is one of the most effective techniques for predicting the peptide bioactivity based on their structure properties. The accuracy of model prediction is highly dependent on the bio-activity of the peptides in its dataset. However, the same peptide used for constructing the database was reported to have obviously different activities in different published articles, which may significantly decrease the prediction accuracy. Based on this, we chose ACE inhibitory (ACE-I) dipeptides that can be absorbed directly into the human small intestine as research object. Ten dipeptides were randomly selected from the literatures for molecular docking with ACE and synthesized to test their activity. Ultimately, a linear equation was developed between bio-activities and docking scores, which was used to revalidate the reliable ACE-I activities of all reported dipeptides for constructing a credible dataset of 3D-QSAR model. The prediction accuracy was significantly enhanced and the model we established had a high Q2 = 0.840 and R2 = 0.998. Furthermore, dipeptide CW was predicted and tested in vitro to achieve the highest ACE-I activity (IC50 = 0.16 μM), and the inhibition mechanism was also investigated. This study introduced a new method for predicting bio-activity with high precision using the 3D-QSAR model.

Ribotoxin deoxynivalenol induces taurocholic acid malabsorption in an in vitro human intestinal model

The trichothecene toxin deoxynivalenol (DON) is a ribotoxic mycotoxin that contaminates cereal-based food. DON binds to ribosomes, thereby inhibiting protein translation and activating stress mitogen-activated protein kinases (MAPK). The activation of MAPK induces pro-inflammatory cytokine production. Emerging evidence showed that DON decreased bile acid reabsorption and apical sodium-dependent bile acid transporter (ASBT) expression in Caco-2 cell layers. We hypothesized that the effect of DON on decreased ASBT mRNA expression is regulated via pro-inflammatory cytokines. We observed that MAPK inhibitors prevented DON to induce IL-8 secretion and prevented the DON-induced downregulation of ASBT mRNA expression. However, DON-induced taurocholic acid (TCA) transport reduction was not prevent by the MAPK inhibitors. We next observed a similarity between the activity of the non-inflammatory ribotoxin cycloheximide and DON to decrease TCA transport, which is consistent with their common ability to inhibit protein synthesis. Together, our results suggest that DON-induced TCA malabsorption is regulated by MAPK activation-induced pro-inflammatory cytokine production and protein synthesis inhibition, both of which are initiated by DON binding to the ribosomes which therefore is the molecular initiating event for the adverse outcome of bile acid malabsorption. This study provides insights into the mechanism of ribotoxins-induced bile acid malabsorption in human intestine.

Biological Function of Antimicrobial Peptides on Suppressing Pathogens and Improving Host Immunity.

The emergence of drug-resistant genes and concerns about food safety caused by the overuse of antibiotics are becoming increasingly prominent. There is an urgent need for effective alternatives to antibiotics in the fields of livestock production and human medicine. Antimicrobial peptides can effectively replace antibiotics to kill pathogens and enhance the immune functions of the host, and pathogens cannot easily produce genes that are resistant to them. The ability of antimicrobial peptides (AMPs) to kill pathogens is associated with their structure and physicochemical properties, such as their conformation, electrical charges, hydrophilicity, and hydrophobicity. AMPs regulate the activity of immunological cells and stimulate the secretion of inflammatory cytokines via the activation of the NF-κB and MAPK signaling pathways. However, there are still some limitations to the application of AMPs in the fields of livestock production and human medicine, including a restricted source base, high costs of purification and expression, and the instability of the intestines of animals and humans. This review summarizes the information on AMPs as effective antibiotic substitutes to improve the immunological functions of the host through suppressing pathogens and regulating inflammatory responses. Potential challenges for the commercial application of AMPs in animal husbandry and human medicine are discussed.