Intestinal dysbacteriosis contributes to decreased intestinal mucosal barrier function and increased bacterial translocation

The effect of the molecular weight of blackberry polysaccharides on gut microbiota modulation and hypoglycemic effect in vivo

Blackberry polysaccharides with certain molecular weight distribution have good bioactivity. In this research, type 2 diabetes mice were used to investigate the hypoglycemic effect of blackberry polysaccharides with three different molecular weights, BBP (603.59 kDa), BBP-8 (408.13 kDa) and BBP-24 (247.62 kDa), through gut microbiota modulation. Blackberry polysaccharides exhibited stronger hypoglycemic activity after degradation, and the FBG of BBP, BBP-8 and BBP-24 was reduced to 20.21 ± 4.17 mmol L-1, 20.6 ± 7.23 mmol L-1 and 17.32 ± 6.59 mmol L-1 and OGTT-AUC was reduced by 14.76%, 19.80% and 25.04%, respectively, after 8-week intervention. Furthermore, 16S rRNA gene sequencing analysis indicated that BBP, BBP-8 and BBP-24 could reshape the diversity and composition of the gut microbiota. From 0 to 4 weeks, the F/B of BBP, BBP-8 and BBP-24 reduced by 56.44%, 47.19% and 62.04%, reaching 3.39, 6.54, and 3.11 in the 8th week, respectively, which suggested the faster utilization of BBP-24. Moreover, the intervention the three blackberry polysaccharides increased the relative abundance of the targeted beneficial bacteria Oscillospira and Bacteroidaceae Bacteroides and decreased the relative abundance of the pathogenic bacterium Allobaculum. In general, the result demonstrated that blackberry polysaccharides with a lower molecular weight are more easily fermented, making the theoretical basis for the development of blackberry polysaccharides as a probiotic food to rapidly regulate intestinal flora for type 2 diabetes.

Armored probiotics for oral delivery

As a kind of intestinal flora regulator, probiotics show great potential in the treatment of many diseases. However, orally delivered probiotics are often vulnerable to unfriendly gastrointestinal environments, resulting in a low survival rate and decreased therapeutic efficacy. Decorating or encapsulating probiotics with functional biomaterials has become a facile yet useful strategy, and probiotics can be given different functions by wearing different armors. This review systematically discusses the challenges faced by oral probiotics and the research progress of armored probiotics delivery systems. We focus on how various functional armors help probiotics overcome different obstacles and achieve efficient delivery. We also introduce the applications of armor probiotics in disease treatment and analyze the future trends of developing advanced probiotics-based therapies.

Dendrobium officinale Polysaccharide Alleviates Type 2 Diabetes Mellitus by Restoring Gut Microbiota and Repairing Intestinal Barrier via the LPS/TLR4/TRIF/NF-kB Axis

Dendrobium officinale polysaccharide (DOP), the main active component, has a variety of bioactivities. In this study, a type 2 diabetes mellitus (T2DM) and antibiotic-induced pseudo-germ-free mouse models were used to investigate the hypoglycemic mechanisms of DOP. The findings showed that DOP ameliorated dysfunctional glucolipid metabolism, lipopolysaccharide (LPS) leakage, and metabolic inflammation levels in T2DM mice. Furthermore, DOP significantly upregulated the mRNA expression of tight junction proteins Claudin-1, Occludin, and ZO-1 and reduced intestinal inflammation and oxidative stress damage through the LPS/TLR4/TRIF/NF-κB axis to repair the intestinal barrier. Interestingly, pseudo-germ-free mouse experiments confirmed that the above beneficial effects of DOP were dependent on gut microbiota. 16S rRNA analysis showed that DOP strongly inhibited the harmful bacterium Helicobacter by 94.57% and facilitated the proliferation of probiotics Allobaculum, Bifidobacterium, and Lactobacillus by 34.96, 139.41, and 88.95%, respectively. Therefore, DOP is capable of rebuilding certain specific intestinal microbiota to restore intestinal barrier injury, which supports the utilization of DOP as a new type of prebiotic in functional foods for T2DM.

Effects of bacteriophage on Salmonella Enteritidis infection in broilers

Bacteriophages (BP) are viruses that can infect bacteria. The present study evaluated the effect of BP on Salmonella infected broilers. A number of 150 day-old broilers were used in a completely randomized design with five treatments that included: (1) basal diet from day 0 to 28; (2) basal diet + 0.3 g/kg of colistin from day 0 to 28; (3) basal diet from day 1 to 13, and basal diet + 0.4 g/kg of colistin from day 14 to 28; (4) basal diet + 1 g/kg of BP from day 0 to 28; (5) basal diet + 1.5 g/kg of BP from day 0 to 28. On day 13, 15 chickens from each treatment were challenged by Salmonella Enteritidis (SE), while fifteen from each treatment were not; instead, they were kept in the same cage with the challenged chickens (exposed chickens). At 7 and 14 days post-challenge, the number of SE and coliform bacteria in the cecum and liver of colistin and BP-fed birds was lower than the control treatment. In exposed and challenged chickens, the height and surface area of villus were greater in the BP and colistin-supplemented groups. Serum concentrations of aspartate aminotransferase and alanine transaminase were greater, while serum albumin and triglycerides concentrations were lower in the control treatment. The liver of the challenged chickens had more pathological lesions than exposed birds. BP significantly decreased PPARγ gene expression in exposed chickens. In the challenged and exposed chickens, TLR4 gene expression was lower in BP and colistin-treated birds as compared to the control. In conclusion, adding BP to the diet from the day of age prevents the spread of Salmonella.

Regulation of Physiological Barrier Function by the Commensal Microbiota

A fundamental characteristic of living organisms is their ability to separate the internal and external environments, a function achieved in large part through the different physiological barrier systems and their component junctional molecules. Barrier integrity is subject to multiple influences, but one that has received comparatively little attention to date is the role of the commensal microbiota. These microbes, which represent approximately 50% of the cells in the human body, are increasingly recognized as powerful physiological modulators in other systems, but their role in regulating barrier function is only beginning to be addressed. Through comparison of the impact commensal microbes have on cell-cell junctions in three exemplar physiological barriers-the gut epithelium, the epidermis and the blood-brain barrier-this review will emphasize the important contribution microbes and microbe-derived mediators play in governing barrier function. By extension, this will highlight the critical homeostatic role of commensal microbes, as well as identifying the puzzles and opportunities arising from our steadily increasing knowledge of this aspect of physiology.

Liangxue Tongyu Prescription Alleviates Brain Damage in Acute Intracerebral Hemorrhage Rats by Regulating Intestinal Mucosal Barrier Function

Background

Liangxue Tongyu prescription (LTP) is a commonly used formula for acute intracerebral hemorrhage (AICH) in clinical practice that has significant ameliorative effects on neurological deficits and gastrointestinal dysfunction, yet the mechanism remains elusive. The aim of this study was to investigate the pathway by which LTP alleviates brain damage in AICH rats.

Methods

The AICH rat models were established by autologous caudal arterial blood injection. The neurological function scores were evaluated before and after treatment. The water content and the volume of Evans blue staining in the brain were measured to reflect the degree of brain damage. RT-PCR was used to detect the inflammatory factors of the brain. Western blotting was used to detect the expression of the tight junction proteins zonula occludens 1 (ZO-1), occludin (OCLN), and claudin (CLDN) in the brain and colon, followed by mucin 2 (MUC2), secretory immunoglobulin A (SIgA), and G protein-coupled receptor 43 (GPR43) in the colon. Flow cytometry was used to detect the ratios of helper T cells 17 (Th17) and regulatory T cells (Treg) in peripheral blood, and the vagus nerve (VN) discharge signals were collected.

Results

LTP reduced the brain damage of the AICH rats. Compared with the model group, LTP significantly improved the permeability of the colonic mucosa, promoted the secretion of MUC2, SigA, and GPR43 in the colon, and regulated the immune balance of peripheral T cells. The AICH rats had significantly faster VN discharge rates and lower amplitudes than normal rats, and these abnormalities were corrected in the LTP and probiotics groups.

Conclusion

LTP can effectively reduce the degree of brain damage in AICH rats, and the mechanism may be that it can play a neuroprotective role by regulating the function of the intestinal mucosal barrier.

Food Peptides, Gut Microbiota Modulation, and Antihypertensive Effects

The gut microbiota is increasingly important in the overall human health and as such, it is a target in the search of novel strategies for the management of metabolic disorders including blood pressure, and cardiovascular diseases. The link between microbiota and hypertension is complex and this review is intended to provide an overview of the mechanism including the production of postbiotics, mitigation of inflammation, and the integration of food biological molecules within this complex system. The focus is on hydrolyzed food proteins and peptides which are less commonly investigated for prebiotic properties. The analysis of available data showed that food peptides are multifunctional and can prevent gut dysbiosis by positively affecting the production of postbiotics or gut metabolites (short-chain fatty acids, polysaccharides, biogenic amines, bile acids). Peptides and the postbiotics then displayed antihypertensive effects via the renin-angiotensin system, the gut barrier, the endothelium, and reduction in inflammation and oxidative stress. Despite the promising antihypertensive effect of the food peptides via the modulation of the gut, there is a lack of human studies as most of the works have been conducted in animal models.

The in Vitro Fermentation of Cordyceps militaris Polysaccharides Changed the Simulated Gut Condition and Influenced Gut Bacterial Motility and Translocation

The motility ability of intestinal lipopolysaccharide (LPS)-producing bacteria determines their translocation to the enterohepatic circulation and works as an infectious complication. In this study, the health effects of Cordyceps militaris polysaccharides (CMPs) were re-evaluated based on whether these polysaccharides could affect the motility of gut commensal LPS-producing bacteria and impede their translocation. The results showed that CMP-m fermentation in the gut could change the chemical environment, leading to a decrease in velocity and a shift in the motility pattern. Further study suggested that detachment/fragmentation of flagella, decreased motor forces, and changed chemical conditions might account for this weakened motility. The adhesion and invasion abilities of gut bacteria were also reduced, with lower expression of virulence-related genes. These results indicated that the health regulation effects of CMP-m might be through decreasing the motility of LPS-producing bacteria, hindering their translocation and therefore reducing the LPS level in the enterohepatic circulation.

Selenium-containing polysaccharide from Spirulina platensis alleviates Cd-induced toxicity in mice by inhibiting liver inflammation mediated by gut microbiota

Selenium-containing polysaccharide from Spirulina platensis (Se-SPP) has been demonstrated to help in inhibiting cadmium-induced injury in mice, but the underlying mechanism has not been determined. This study aimed to investigate the beneficial effects of Se-SPP on alleviating Cd-induced toxicity in mice by targeting liver inflammatory and gut microbiota. Se-SPP supplementation for 28 days in Cd-induced toxic mice significantly mitigated liver pathological damage and inflammation, which was correlated to the upregulation of antioxidant enzyme activity. Furthermore, Se-SPP effectively restored Cd-induced disruption of the intestinal barrier compared to model group, as indicated by the depletion of Muribaculaceae and the enrichment of Ruminococcaceae. Spearman's correlation analysis revealed that the Se-SPP-altered microbes were highly correlated with inflammation-related indexes in Cd-induced toxic mice. Noteworthily, the modulation of Se-SPP on the Ruminococcaceae population contributed to the improvement of Cd-induced inflammation-related diseases by downregulating the tumor necrosis factor-α (TNF-α) and interferon-γ (IFN-γ) in the liver. These findings suggested that Se-SPP may act as prebiotics for ameliorating Cd-induced toxicity in mice by inhibiting liver inflammation mediated by gut microbiota, and target-specific microbiota of Cd-induced inflammation-related diseases deserve further attention.

Effects of bacteriophage supplement on the growth performance, microbial population, and PGC-1α and TLR4 gene expressions of broiler chickens

Bacteriophages (BP) are viruses that invade bacteria and propagate inside them, leading to the lysis of the bacterial cells. The aim of this study was to investigate the effect of adding BP to the broiler's diet and its effect on the performance, morphology and bacterial population of the gut, some immune responses and expression of some intestinal genes. Accordingly, dietary treatments were as follows: basal diet (control), and control + 0.3 g/kg colistin or 0.5, 1 and 1.5 g BP/kg of diet. BP increased the body weight gain and reduced the feed conversion ratio (FCR), as compared to the colistin treatment, in the finisher and overall period (P < 0.05). European efficiency factor was significantly higher in 1.5 g BP-fed birds, as compared to the control and colistin treatments. meanwhile, bacteriophage and colistin-fed birds had higher Lactobacillus and lowered coliform bacteria counts, as compared to the control treatment (P < 0.05). Cecal concentrations of propionate in the 1.5 g BP-fed birds were higher than those in the control treatment (P < 0.05). BP-fed birds had a significantly increased villus height to crypt depth ratio, as compared to the control treatment. BP increased the serum concentrations of the total antibody, immunoglobulin (Ig) M, and IgG, as compared to the control treatment (P < 0.05). In the ileum, the expression of the Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) gene was decreased by dietary BP supplementation (P < 0.05). Furthermore, Toll-like receptor 4 (TLR4) gene expression was down-regulated in the BP-fed birds, whereas Interleukin 10 (IL-10) gene expression was up-regulated (P < 0.05). Overall, the use of BP may be a promising alternative to growth-promoting antibiotics in broilers by altering the gastrointestinal tract microbiota, enhancing immunological responses and improving the gut's morphology.

Hylkema M, Bartel S, Schloter M, Krauss‐Etschmann S. Oral application of vancomycin alters murine lung microbiome and pulmonary immune responses

Early life exposures to antibiotics negatively impact respiratory health and are associated with an increased risk of childhood asthma. It is explained that the lung is inclined to develop chronic inflammatory phenotypes due to early antibiotic alteration in the gut microbiome. We investigated whether a gut-targeted antibiotic has an impact on the lung microbiome and on pulmonary immunity. Fourteen-day old C57BL/6 mice were administered with vancomycin via oral gavage for 3 days (1 time/day). Control groups were treated with clarithromycin and phosphate-buffered saline (PBS), respectively. Five days after treatment, the cecum and lung microbiome, and pulmonary immune response were analyzed. Vancomycin treatment decreased the relative abundance of the genera Clostridium XIVa and Alistipes and the family Lachnospiraceae in the cecum. Furthermore, the relative abundance of the family Parabacteroidetes and the genus Lactobacillus were increased, whereas the abundance of the phylum Firmicutes was decreased. In the lung, vancomycin treatment reduced bacteria belonging to Clostridium XIVa and the family Lachnospiraceae as compared to those in the clarithromycin treated group. Lung cells from the vancomycin-treated mice released higher levels of interleukin (IL)-4 and IL-13 compared to those from the PBS group, and increased levels of IL-6, IFN-γ, and TNFα compared to lung cells from the clarithromycin and PBS treated mice. Our pilot study suggests that alteration in the gut microbiome could affect bacterial composition and immunity of the lung hence proposes a gut-lung microbiome axis in early life.

The Role of Probiotics in Alleviating Postweaning Diarrhea in Piglets From the Perspective of Intestinal Barriers

Early weaning of piglets is an important strategy for improving the production efficiency of sows in modern intensive farming systems. However, due to multiple stressors such as physiological, environmental and social challenges, postweaning syndrome in piglets often occurs during early weaning period, and postweaning diarrhea (PWD) is a serious threat to piglet health, resulting in high mortality. Early weaning disrupts the intestinal barrier function of piglets, disturbs the homeostasis of gut microbiota, and destroys the intestinal chemical, mechanical and immunological barriers, which is one of the main causes of PWD in piglets. The traditional method of preventing PWD is to supplement piglet diet with antibiotics. However, the long-term overuse of antibiotics led to bacterial resistance, and antibiotics residues in animal products, threatening human health while causing dysbiosis of gut microbiota and superinfection of piglets. Antibiotic supplementation in livestock diets is prohibited in many countries and regions. Regarding this context, finding antibiotic alternatives to maintain piglet health at the critical weaning period becomes a real emergency. More and more studies showed that probiotics can prevent and treat PWD by regulating the intestinal barriers in recent years. Here, we review the research status of PWD-preventing and treating probiotics and discuss its potential mechanisms from the perspective of intestinal barriers (the intestinal microbial barrier, the intestinal chemical barrier, the intestinal mechanical barrier and the intestinal immunological barrier) in piglets.

The combination of berberine and evodiamine ameliorates high-fat diet-induced non-alcoholic fatty liver disease associated with modulation of gut microbiota in rats

Nonalcoholic fatty liver disease (NAFLD) is considered to be a manifestation of hepatic metabolic syndrome. Some studies on the pathogenesis of NAFLD by targeting gut microbiota have attracted wide attention. Previous studies have demonstrated the positive effects of berberine and evodiamine on metabolic diseases and gut microbiota dysbiosis. However, it is not known whether the combination of berberine and evodiamine (BE) can prevent the development of high-fat diet (HFD)-induced NAFLD. Therefore, we aimed to explore the protective effects of BE on the development of HFD-induced NAFLD from the perspective of the gut microbiota. Gut microbiota profiles were established by high throughput sequencing of the bacterial 16S ribosomal RNA gene. The effects of BE on liver and intestinal tissue, intestinal barrier integrity, and hepatic inflammation were also investigated. The results showed that the abundance and diversity of gut microbiota were enriched by BE treatment, with an increase in beneficial bacteria, such as Lactobacillus, Ruminococcus, and Prevotella, and a decrease in pathogenic bacteria such as Fusobacterium and Lachnospira. In addition, BE effectively improved liver fat accumulation and tissue damage, inhibited the apoptosis of intestinal epithelial cells, increased the contents of intestinal tight junction proteins, and decreased the expression of pro-inflammatory factors. Consequently, BE treatment could be an effective and alternative strategy for alleviating NAFLD by modulating gut microbiota and safeguarding the intestinal barrier.

The interaction among gut microbes, the intestinal barrier and short chain fatty acids

The mammalian gut is inhabited by a massive and complicated microbial community, in which the host achieves a stable symbiotic environment through the interdependence, coordination, reciprocal constraints and participation in an immune response. The interaction between the host gut and the microbiota is essential for maintaining and achieving the homeostasis of the organism. Consequently, gut homeostasis is pivotal in safeguarding the growth and development and potential productive performance of the host. As metabolites of microorganisms, short chain fatty acids are not only the preferred energy metabolic feedstock for host intestinal epithelial cells, but also exert vital effects on antioxidants and the regulation of intestinal community homeostasis. Herein, we summarize the effects of intestinal microorganisms on the host gut and the mechanisms of action of short chain fatty acids on the four intestinal barriers of the organism, which will shed light on the manipulation of the intestinal community to achieve precise nutrition for specific individuals and provide a novel perspective for the prevention and treatment of diseases.

Succession of the Gut Microbiome in the Tibetan Population of Minjiang River Basin

Tibetans are one of the oldest ethnic groups in China and South Asia. Based on the analysis of 1,059 Tibetans in the Minjiang River basin at an altitude of 500–4,001 m, we found that the dominant phyla of the Tibetan population were Bacteroidota and Firmicutes, and the main genera were Prevotella and Bacteroides, which were mostly in consistent with other nationalities. We further evaluated in total 115 parameters of seven categories, and results showed that altitude was the most important factor affecting the variation in the microbial community. In the process of emigration from high altitudes to the plain, the gut microbial composition of late emigrants was similar to that of plateau aborigines. In addition, regarding immigration from low altitude to high altitude, the microbial community became more similar to that of high altitude population with the increase of immigration time. Changes in these microbes are related to the metabolism, disease incidence and cell functions of the Tibetan population. The results of other two cohorts (AGP and Z208) also showed the impact of altitude on the microbial community. Our study demonstrated that altitude of habitation is an important factor affecting the enterotype of the microflora in the Tibetan population and the study also provided a basis to explore the interaction of impact parameters with gut microbiome for host health and diseases.

Physiologically Inspired Mucin Coated Escherichia coli Nissle 1917 Enhances Biotherapy by Regulating the Pathological Microenvironment to Improve Intestinal Colonization

The delivery of probiotics to the microbiota is a promising method to prevent and treat diseases. However, oral probiotics will suffer from gastrointestinal insults, especially the pathological microenvironment of inflammatory diseases such as reactive oxygen species (ROS) and the exhausted mucus layer, which can limit their survival and colonization in the intestinal tract. Inspired by the fact that probiotics colonized and grew in the mucus layer under physiological conditions, we developed a strategy for a super probiotic (EcN@TA-Ca²⁺@Mucin) coated with tannic acid and mucin via layer-by-layer technology. We demonstrated that mucin endows probiotics with superior resistance to the harsh environment of the gastrointestinal tract and with strong adhesiveness to the intestine through its interaction with mucus, which enhanced colonization and growth of probiotics in the mucus layer without removing the coating. Moreover, EcN@TA-Ca²⁺@Mucin can distinctly down-regulate inflammation with ROS scavenging and reduce the side effects of bacterial translocation in inflammatory bowel diseases, increasing the abundance and diversity of the gut microflora. We envision that it is a powerful platform to improve the colonization of probiotics by regulating the pathological microenvironment, which is expected to provide an important perspective for applying the intestinal colonization of probiotics to treat a variety of diseases.

Hypoglycemic effect of polysaccharide from Astragalus membranaceus on type 2 diabetic mice based on “gut microbiota-mucosal barrier”

Astragalus membranaceus polysaccharide (APP), the main active constituent possesses numerous bioactivities. In this research, the T2DM model mice was combined with streptozotocin to study the hypoglycemic effect and mechanism of...

Cardiovascular Health and The Intestinal Microbial Ecosystem: The Impact of Cardiovascular Therapies on The Gut Microbiota

It has become evident over the past several years that the intestinal microbial ecosystem plays a critical role in the development and prevention of cardiovascular diseases (CVDs) and other metabolic disorders, such as hypertension, obesity, diabetes mellitus, and metabolic syndrome. The intestinal microbiota ecosystem functions as a major virtual endocrine organ that interacts and responds to molecules' signals within the host. Several meta-organismal pathways are involved in the gut-host interaction, including trimethylamine-N-oxide (TMAO) and short-chain fatty acids (SCFA). Host phenotype and cardiovascular diseases (CVDs) varying from hypertension, insulin resistance, and obesity to more specific inflammatory processes, such as atherosclerosis and hypercoagulability, have shown to be affected by the gut-host interaction. Additionally, several studies that involved animals and humans demonstrated a striking connection between the development of new CVDs and an imbalance in the gut microbiota composition along with the presence of their derived metabolites. Through this review article, we aim to evaluate the role of the normal gut microbiota ecosystem, its association with CVDs, effects of the therapies used to control and manage CVDs in the gut microbiota environment and explore potential therapeutic interventions to amplify disease outcomes in patients with CVDs.

Review of gut nanotoxicology in mammals: Exposure, transformation, distribution and toxicity

Nanomaterials are increasingly used in food processing, daily necessities and other fields due to their excellent properties, and increase the environmental contamination. Human beings will inevitably come into contact with these nanomaterials through multiple exposure routes especially oral exposure. The intestine is an important organ for nutrient absorption and physiologic barrier, which may be the main target of nanoparticles (NPs) exposure. However, for a long time, research on the toxicity of NPs has mainly focused on organs such as liver, kidney and brain. There are few assessment data over the intestinal safety. Recently, as reported, NPs can be translocated to the intestinal part in mammals and would be distributed in different substructures of intestines, thus causing damage to the structure and function of the intestine, in which the gut microbiota and its metabolites play important roles. In addition, due to the special physiological environment of gut, nanomaterials will undergo complex transformations that may cause different biological effects from their original form. Therefore, this review aims to assess the potential adverse effects of NPs on intestine and its possible mechanisms through the results of in vivo mammalian experiments. In addition, the exposure pathway, biodistribution and biotransformation of NPs in the intestine are also considered. We hope this review will arouse people's attention to the intestinal nanotoxicology and provide basic information for further related studies.

Effects of Non-directional Mechanical Trauma on Gastrointestinal Tract Injury in Rats

Mechanical trauma can (MT) cause secondary injury, such as cardiomyocyte apoptosis and cardiac dysfunction has been reported. However, the effects of mechanical trauma on gastrointestinal tract is unclear. This study aims to observe the main location and time of gastrointestinal tract injury caused by non-directional trauma and explain the reason of the increase of LPS in blood caused by mechanical injury. Morphological changes in the stomach, ileum and cecum at different time points after MT were observed in this experiment. The results reveal that the injury to the cecal mucosa in the rats was more obvious than that in the ileum and the stomach. The cecal epithelial cell junction was significantly widened at 20 min after MT, and the plasma LPS and D-lactic acid concentrations increased significantly at the same time point. In addition, some bacterial structures in the widened intercellular space and near the capillary wall of the cecal mucosa were detected at 12 h after MT. This finding suggests that the main reason for the increase in LPS in plasma after MT is cecal mucosal injury. This study is important for the early intervention of the gastrointestinal tract to prevent secondary injury after MT.

Role of Gut Microbiota and Their Metabolites on Atherosclerosis, Hypertension and Human Blood Platelet Function: A Review

Emerging data have demonstrated a strong association between the gut microbiota and the development of cardiovascular disease (CVD) risk factors such as atherosclerosis, inflammation, obesity, insulin resistance, platelet hyperactivity, and plasma lipid abnormalities. Several studies in humans and animal models have demonstrated an association between gut microbial metabolites such as trimethylamine-N-oxide (TMAO), short-chain fatty acids, and bile acid metabolites (amino acid breakdown products) with CVD. Human blood platelets are a critical contributor to the hemostatic process. Besides, these blood cells play a crucial role in developing atherosclerosis and, finally, contribute to cardiac events. Since the TMAO, and other metabolites of the gut microbiota, are asociated with platelet hyperactivity, lipid disorders, and oxidative stress, the diet-gut microbiota interactions have become an important research area in the cardiovascular field. The gut microbiota and their metabolites may be targeted for the therapeutic benefit of CVD from a clinical perspective. This review's main aim is to highlight the complex interactions between microbiota, their metabolites, and several CVD risk factors.

A polysaccharide from Fagopyrum esculentum Moench bee pollen alleviates microbiota dysbiosis to improve intestinal barrier function in antibiotic-treated mice

Antibiotics are the most commonly used clinical drugs for anti-infection, but they can also destroy normal microorganisms and cause intestinal barrier dysfunction. To elucidate the effects and mechanism of a water-soluble polysaccharide from Fagopyrum esculentum Moench bee pollen (WFPP) on intestinal barrier integrity in antibiotic-treated mice, BALB/c mice were exposed to a broad-spectrum antibiotic (ceftriaxone) or not (control), and were administered low-, medium- and high-dose WFFP (100 mg kg^-1, 200 mg kg^-1 and 400 mg kg^-1, respectively) daily by oral gavage for 3 weeks. Mice treated with ceftriaxone displayed symptoms of growth retardation, atrophy of immune organs including thymus and spleen, increased gut permeability, and intestinal barrier damage, which were restored after intervention with WFFP at different doses. Moreover, the beneficial effects of WFFP were closely associated with enhanced intestinal sIgA secretion and reduced inflammatory response. Furthermore 16S rDNA gene sequencing revealed that WFPP elevated microbial diversity and richness and changed the community structure, therefore, alleviating microbiota dysbiosis caused by ceftriaxone. Interestingly, WFPP could modulate the abundance of sIgA secretion-related bacteria (e.g. Proteobacteria) and inflammation-related bacteria (e.g. Enterococcus). Therefore, WFPP can relieve antibiotic-induced microbiota dysbiosis to improve intestinal barrier integrity by increasing intestinal sIgA secretion and inhibiting inflammation.

Rhubarb Enema Improved Colon Mucosal Barrier Injury in 5/6 Nephrectomy Rats May Associate With Gut Microbiota Modification

Chronic kidney disease (CKD) is often accompanied with colon mucosal barrier damage and gut microbiota disturbance, which strongly associate with up-regulated inflammation and kidney tubulointerstitial fibrosis. However, few interventions could protect the damaged barrier effectively. Rheum palmatum L or rhubarb is a common herbal medicine which is widely used to protect the colon mucosal barrier. In previous studies, we found that rhubarb intervention may reduce renal inflammation and tubulointerstitial fibrosis, via gut microbiota modification. However, whether intestinal barrier function could be improved by rhubarb intervention and the relationship with intestinal flora are still unknown. Therefore, we investigated the effects of rhubarb enema on intestinal barrier, and further analyzed the relationship with gut microbiota in 5/6 nephrectomy rats. Results indicated that rhubarb enema improved the intestinal barrier, regulated gut microbiota dysbiosis, suppressed systemic inflammation, and alleviated renal fibrosis. More specifically, rhubarb enema treatment inhibited the overgrowth of conditional pathogenic gut bacteria, including Akkermansia, Methanosphaera, and Clostridiaceae in CKD. The modification of gut microbiota with rhubarb intervention displayed significant correlation to intestinal barrier markers, TLR4–MyD88–NF-κB inflammatory response, and systemic inflammation. These results revealed that rhubarb enema could restore intestinal barrier by modifying several functional enteric bacteria, which may further explain the renal protection mechanism of the rhubarb enema.

Oral administration of vancomycin to neonatal mice could alter their immunity and allergic sensibility late in adulthood

The prevalence of allergy has increased over the past decades, and this may be attributed in part to the intestinal microbiota dysfunction caused by antibiotics during early life. In this study, we evaluated how vancomycin could impair the intestinal microbiota during early life and then, consequently, alter susceptibilities to allergic diseases and related immunity in late adulthood. BALB/c (n=54) neonatal mice were used in this study. Mice in the vancomycin group were orally administered vancomycin for 21 days, while those in the allergy and control groups were perfused with the same volume of saline solution. Then, mice in the allergy and vancomycin groups were immunized with intraperitoneal ovalbumin with alum. At postnatal day 21, vancomycin significantly alter the fecal microbiota, with lower Bacteroidetes and Firmicutes counts and higher Proteobacteria counts. At postnatal day 56, the Bacteroidetes count was still significantly lower in vancomycin-treated mice. The serum IgE level in the control group was significantly lower than that in the vancomycin and allergy groups. The serum interleukin (IL)-6 level and the IL-4/interferon (IFN)-γ values were significantly higher in the vancomycin-treated mice, but the serum IL-17A level was lower than that in the control group. These results indicate that modifications of the intestinal microbiota composition during early life may be, at least in part, the key mechanism underlying the effect of vancomycin that influences the immune function of host animals in the adult stages.

Autophagy induction by rapamycin ameliorates experimental colitis and improves intestinal epithelial barrier function in IL-10 knockout mice

BACKGROUND

An impairment of the intestinal barrier function is one of the major characteristics of Crohn's disease (CD). This study aimed to evaluate the impact of autophagy induction by rapamycin on the intestinal epithelial barrier function in CD model mice.

METHODS

IL-10 knockout (IL-10 KO) mice were used as the human CD models in this study. All the mice were randomly assigned into four groups, (a) wild-type (WT) group; (b) IL-10 KO group; (c) IL-10 KO + rapamycin group and (d) IL-10 KO + 3-methyladenine (3-MA), containing 6 mice in each group. The disease activity index (DAI), histology, pro-inflammatory cytokines and chemotactic factors in colon tissues, intestinal and colonic permeability, distributions and expressions of tight junction (TJ) proteins, epithelial apoptosis of mice in four groups were evaluated and compared.

RESULTS

Autophagy induction by rapamycin treatment ameliorated DAI and histological colitis, decreased pro-inflammatory cytokines (TNF-α, IFN-γ and IL-17) and chemotactic factors (CXCL-1 and CXCL-2), decreased intestinal and colonic permeability, improved the distribution and expression of TJ proteins in IL-10 KO mice.

CONCLUSION

Autophagy induction by rapamycin significantly improved intestinal barrier function and protected IL-10 KO mice from the experimental chronic colitis.

Biomarkers of intestinal barrier function in multiple sclerosis are associated with disease activity

BACKGROUND

Recent evidence suggests a role for the gut-brain axis in the pathophysiology of multiple sclerosis (MS).

MATERIALS AND METHODS

We studied biomarkers of intestinal permeability in 126 people with MS (57 relapsing-remitting multiple sclerosis (RRMS) and 69 progressive MS) and in a group of healthy controls for comparison. Serum/plasma concentrations of zonulin (a regulator of enterocyte tight junctions), tight junction proteins (ZO-1 and occludin), intestinal fatty acid binding protein (IFABP)/ileal bile acid binding protein (IBABP), D-lactate, and lipopolysaccharide (LPS) binding protein were measured.

RESULTS

Zonulin concentrations were significantly higher when a concurrent magnetic resonance imaging (MRI) confirmed the presence of blood-brain barrier (BBB) disruption (Gad+ RRMS) and were correlated with tight junction proteins. IBABP and D-lactate were elevated in people with RRMS compared to controls, but did not discriminate between Gad+ and Gad- subgroups. Baseline zonulin concentrations were associated with 1-year disease progression in progressive MS.

CONCLUSIONS

People with MS have altered biomarkers of intestinal barrier integrity. Zonulin concentrations are associated with 1-year disease progression in progressive MS and closely mirror BBB breakdown in RRMS. Zonulin may mediate breakdown of both the intestinal barrier and the BBB in gut dysbiosis through the regulation of tight junctions. This could explain how the gut-brain axis modulates neuroinflammation in MS.

Intestinal translocation of enterococci requires a threshold level of enterococcal overgrowth in the lumen

Enterococci are subdominant members of the human gastrointestinal microbiota. Enterococcus faecalis is generally harmless for healthy individuals, but it can cause a diverse range of infections in immunodeficient or elderly patients with severe underlying diseases. In this study, we analysed the levels of intestinal translocation of indigenous enterococci in C57BL/6, CF-1 and CX3CR1^−/− mice upon clindamycin antibiotic-induced dysbiosis. We found that C57BL/6 was the most permissive model for enterococcal translocation and that initiation of E. faecalis translocation coincided with a threshold of enterococcal colonisation in the gut lumen, which once reached, triggered E. faecalis dissemination to deeper organs. We showed that the extent to which E. faecalis clinical strain VE14821 competed with indigenous enterococci differed between the C57BL/6 and CX3CR1^−/− models. Finally, using a simplified gnotobiotic model, we observed E. faecalis crossing an intact intestinal tract using intestinal epithelial cells as one route to reach the lamina propria. Our study opens new perspectives for assessing the effect of various immunodeficiencies and for investigating mechanisms underlying enterococcal translocation.

Candida albicans induces mucosal bacterial dysbiosis that promotes invasive infection

Infectious complications are a common cause of morbidity and mortality in cancer patients undergoing chemotherapy due to increased risk of oral and gastrointestinal candidiasis, candidemia and septicemia. Interactions between C. albicans and endogenous mucosal bacteria are important in understanding the mechanisms of invasive infection. We published a mouse intravenous chemotherapy model that recapitulates oral and intestinal mucositis, and myelosuppression in patients receiving 5-fluorouracil. We used this model to study the influence of C. albicans on the mucosal bacterial microbiome and compared global community changes in the oral and intestinal mucosa of the same mice. We validated 16S rRNA gene sequencing data by qPCR, in situ hybridization and culture approaches. Mice receiving both 5Fu and C. albicans had an endogenous bacterial overgrowth on the oral but not the small intestinal mucosa. C. albicans infection was associated with loss of mucosal bacterial diversity in both sites with indigenous Stenotrophomonas, Alphaproteobacteria and Enterococcus species dominating the small intestinal, and Enterococcus species dominating the oral mucosa. Both immunosuppression and Candida infection contributed to changes in the oral microbiota. Enterococci isolated from mice with oropharyngeal candidiasis were implicated in degrading the epithelial junction protein E-cadherin and increasing the permeability of the oral epithelial barrier in vitro. Importantly, depletion of these organisms with antibiotics in vivo attenuated oral mucosal E-cadherin degradation and C. albicans invasion without affecting fungal burdens, indicating that bacterial community changes represent overt dysbiosis. Our studies demonstrate a complex interaction between C. albicans, the resident mucosal bacterial microbiota and the host environment in pathogenesis. We shed significant new light on the role of C. albicans in shaping resident bacterial communities and driving mucosal dysbiosis.

Alteration in gut microbiota caused by time-restricted feeding alleviate hepatic ischaemia reperfusion injury in mice

Time-restricted feeding (TRF), that is, no caloric intake for 14-16 hours each day leads to favourable nutritional outcomes. This study is the first to investigate TRF through a surgical perspective verifying its efficacy against liver ischaemia reperfusion (I/R) injury. We randomly assigned 100 10-week-old wild-type male C57BL/6 mice into two feeding regimens: TRF and ad libitum access to food. Main outcomes were evaluated at 6, 12 and 24 hours post-I/R surgery after 12 weeks of intervention. TRF group demonstrated minor liver injury via histological study; lower serum levels of liver enzymes, glucose and lipids; higher concentrations of free fatty acid and β-hydroxybutyrate; decreased oxidative stress and inflammatory biomarkers; as well as less severe cell apoptosis and proliferation. Further exploration indicated better gut microenvironment and intestinal epithelial tight junction function. TRF employed its positive influence on a wide spectrum of biochemical pathways and ultimately revealed protective effect against hepatic I/R injury possibly through adjusting the gut microbiota. The results referred to a strong indication of adopting better feeding pattern for surgical patients.

Effects of dietary supplementation with Lactobacillus acidophilus on the performance, intestinal physical barrier function, and the expression of NOD-like receptors in weaned piglets

Lactobacillus supplementation is beneficial to the barrier function of the intestinal physical barrier in piglets. However, the mechanisms underlying this beneficial function remain largely unknown. Here, we investigated the effects of dietary supplementation with Lactobacillus acidophilus on the performance, intestinal physical barrier functioning, and NOD-like receptors (NLRs) expression in weaned piglets. Sixteen weaned piglets were randomly allocated to two groups. The control group received a corn-soybean basal diet, while the treatment group received the same diet adding 0.1% L. acidophilus, for 14 days. As a result, dietary L. acidophilus supplementation was found to increase the average daily gain (ADG) (P < 0.05), reduced serum diamine oxidase (DAO) activity (P < 0.05), increased the mRNA expression and protein abundance of occludin in the jejunum and ileum (P < 0.01), reduced the mRNA levels of NOD1 (P < 0.01), receptor interacting serine/threonine kinase 2 (RIPK2) (P < 0.05), nuclear factor κB (NF-κB) (P < 0.01), NLR family pyrin domain containing 3 (NLRP3) (P < 0.01), caspase-1 (P < 0.01), interleukin 1β (IL-1β) (P < 0.05) and IL-18 (P < 0.01) in the jejunum tissues of the weaned pigs. The expression of NLRP3 (P < 0.05), caspase-1 (P < 0.01), IL-1β (P < 0.05) and IL-18 (P < 0.05) was also reduced in the ileum tissues of the weaned pigs. These results showed that L. acidophilus supplementation improves the growth performance, enhances the intestinal physical barrier function, and inhibits the expression of NOD1 and NLRP3 signaling-pathway-related genes in jejunum and ileum tissues. They also suggest that L. acidophilus enhances the intestinal physical barrier functioning by inhibiting IL-1β and IL-18 pro-inflammatory cytokines via the NOD1/NLRP3 signaling pathway in weaned piglets.

The Role of Gut Microbiota in Atherosclerosis and Hypertension

In recent years, accumulating evidence has indicated the importance of gut microbiota in maintaining human health. Gut dysbiosis is associated with the pathogenesis of a number of metabolic diseases including obesity, type 2 diabetes mellitus (T2DM), non-alcoholic fatty liver disease (NAFLD), and cardiovascular diseases (CVDs). Indeed, CVD has become the leading cause of death worldwide, especially in developed countries. In this review, we mainly discuss the gut microbiota-involved mechanisms of CVD focusing on atherosclerosis and hypertension, two major risk factors for serious CVD. Then, we briefly discuss the prospects of gut microbiota-targeted therapeutic strategies for the treatment of CVD in the future.

Brain-derived neurotrophic factor preserves intestinal mucosal barrier function and alters gut microbiota in mice

The intestinal mucosal barrier (IMB) enables the intestine to provide adequate containment of luminal microorganisms and molecules while preserving the ability to absorb nutrients. In this study, we explored the effect of brain-derived neurotrophic factor (BDNF) on IMB function and gut microbiota in mice. BDNF gene knock-out mice (the BDNF^+/- group) and wild-type mice (the BDNF^+/+ group) were selected. The gut microbiota of these mice was analyzed by denaturing gradient gel electrophoresis (DGGE) assay. The ultrastructure of the ileum and the colonic epithelium obtained from decapitated mice were observed by transmission electron microscopy. The protein expression of epithelial tight junction proteins, zonula occludens-1 (ZO-1) and occludin was detected by immunohistochemistry staining. The protein expression of claudin-1 and claudin-2 was determined by Western blotting. The DGGE band patterns of gut microbiota in the BDNF^+/- group were significantly different from that in the BDNF^+/+ group, which indicated that the BDNF expression alters the gut microbiota in mice. Compared with the BDNF^+/+ group, the BDNF^+/- group presented no significant difference in the ultrastructure of ileal epithelium; however, a significant difference was observed in the colonic epithelial barrier, manifested by decreased microvilli, widening intercellular space and bacterial invasion. Compared with the BDNF^+/+ group, the expression of ZO-1 and occludin in the BDNF^+/- group was significantly decreased. The expression of claudin-1 in the BDNF^+/- group was significantly reduced, while the expression of claudin-2 was elevated. These findings indicate that BDNF preserves IMB function and modulates gut microbiota in mice.

Vancomycin and ceftriaxone can damage intestinal microbiota and affect the development of the intestinal tract and immune system to different degrees in neonatal mice

This study aimed to determine how antibiotic-driven intestinal dysbiosis impairs the development and differentiation of the digestive tract and immune organs of host animals. BALB/C neonatal mice were orally administered ceftriaxone or vancomycin from postnatal day 1 to day 21 and sacrificed on day 21. The diversity and abundance of the intestinal bacteria, morphological changes and barrier function of intestinal tract, and the splenic CD4+CD25+Foxp3+ T cells were investigated. The gut microbiota and intestinal tissue were damaged, and the numbers of Ki67-, Muc2- and ZO-1-positive cells were significantly decreased in the antibiotic treatment groups. Furthermore, the administration of ceftriaxone, but not vancomycin, led to a significant reduction in the abundance of splenic CD4+CD25+Foxp3+ T cells. Each antibiotic caused intestinal dysbiosis and characteristically influenced the regeneration of intestinal epithelial cells, formation of the intestinal mucus layer and tight junctions, and differentiation of splenic Foxp3+ Treg cells of the neonatal mice before any clinical side effects were observed. The potent ability of each antibiotic to affect the makeup of intestinal commensal microbiota may be a key determinant of the spectrum of antibiotics and influence the health of the host animal, at least partly.

The gut microbiota as a novel regulator of cardiovascular function and disease

The gut microbiome has emerged as a critical regulator of human physiology. Deleterious changes to the composition or number of gut bacteria, commonly referred to as gut dysbiosis, has been linked to the development and progression of numerous diet-related diseases, including cardiovascular disease (CVD). Most CVD risk factors, including aging, obesity, certain dietary patterns, and a sedentary lifestyle, have been shown to induce gut dysbiosis. Dysbiosis is associated with intestinal inflammation and reduced integrity of the gut barrier, which in turn increases circulating levels of bacterial structural components and microbial metabolites that may facilitate the development of CVD. The aim of the current review is to summarize the available data regarding the role of the gut microbiome in regulating CVD function and disease processes. Particular emphasis is placed on nutrition-related alterations in the microbiome, as well as the underlying cellular mechanisms by which the microbiome may alter CVD risk.

Establishment and evaluation of an experimental rat model for high-altitude intestinal barrier injury

In the present study an experimental high-altitude intestinal barrier injury rat model was established by simulating an acute hypoxia environment, to provide an experimental basis to assess the pathogenesis, prevention and treatment of altitude sickness. A total of 70 healthy male Sprague-Dawley rats were divided into two groups: Control group (group C) and a high-altitude hypoxia group (group H). Following 2 days adaptation, the rats in group H were exposed to a simulated 4,000-m, high-altitude hypoxia environment for 3 days to establish the experimental model. To evaluate the model, bacterial translocation, serum lipopolysaccharide level, pathomorphology, ultrastructure and protein expression in rats were assessed. The results indicate that, compared with group C, the rate of bacterial translocation and the apoptotic index of intestinal epithelial cells were significantly higher in group H (P<0.01). Using a light microscope it was determined that the intestinal mucosa was thinner in group H, there were fewer epithelial cells present and the morphology was irregular. Observations with an electron microscope indicated that the intestinal epithelial cells in group H were injured, the spaces among intestinal villi were wider, the tight junctions among cells were open and lanthanum nitrate granules (from the fixing solution) had diffused into the intestinal mesenchyme. The expression of the tight junction protein occludin was also decreased in group H. Therefore, the methods applied in the present study enabled the establishment of a stable, high-altitude intestinal barrier injury model in rats.

Research status of radiation induced gastroduodenal injury

With the development of modern radiotherapy techniques, such as three dimensional conformal radiotherapy, Gamma-knife treatment, and tomotherapy, patients who have abdominal tumors like liver cancer, pancreatic cancer, and colon cancer can live longer. The wide use of radiation therapy increases the incidence of gastroduodenal radioactive injury. This article reviews the pathogenesis and pathological characteristic of radiation induced gastroduodenal injury, factors influencing the injury, and the diagnosis and treatment of radiation induced gastroduodenal injury. Currently, there have been few studies on the mechanism of radiation induced gastroduodenal injury. The optimal timing of endoscopic examination after radiotherapy is still inconclusive. V25 for the stomach, V35 for the duodenum and aV55 Gy for the duodenum are predictive factors for gastroduodenal toxicity (>grade 2, CTCAE3.0). There has been no treatment standard for curing radiation induced gastroduodenitis. Traditional Chinese medicine has unique advantages in the prevention and control of radiation induced gastroduodenal injury.

DHA protects against experimental colitis in IL-10-deficient mice associated with the modulation of intestinal epithelial barrier function

A defect in the intestinal barrier is one of the characteristics of Crohn's disease (CD). The tight junction (TJ) changes and death of epithelial cells caused by intestinal inflammation play an important role in the development of CD. DHA, a long-chain PUFA, has been shown to be helpful in treating inflammatory bowel disease in experimental models by inhibiting the NF-κB pathway. The present study aimed at investigating the specific effect of DHA on the intestinal barrier function in IL-10-deficient mice. IL-10-deficient mice (IL-10(-/-)) at 16 weeks of age with established colitis were treated with DHA (i.g. 35.5 mg/kg per d) for 2 weeks. The severity of their colitis, levels of pro-inflammatory cytokines, epithelial gene expression, the distributions of TJ proteins (occludin and zona occludens (ZO)-1), and epithelial apoptosis in the proximal colon were measured at the end of the experiment. DHA treatment attenuated the established colitis and was associated with reduced infiltration of inflammatory cells in the colonic mucosa, lower mean histological scores and decreased levels of pro-inflammatory cytokines (IL-17, TNF-α and interferon-γ). Moreover, enhanced barrier function was observed in the DHA-treated mice that resulted from attenuated colonic permeability, rescued expression and corrected distributions of occludin and ZO-1. The results of the present study indicate that DHA therapy may ameliorate experimental colitis in IL-10(-/-) mice by improving the intestinal epithelial barrier function.

Fecal microbiota transplantation and bacterial consortium transplantation have comparable effects on the re-establishment of mucosal barrier function in mice with intestinal dysbiosis

Fecal microbiota transplantation (FMT) is a promising therapy, despite some reports of adverse side effects. Bacterial consortia transplantation (BCT) for targeted restoration of the intestinal ecosystem is considered a relatively safe and simple procedure. However, no systematic research has assessed the effects of FMT and BCT on immune responses of intestinal mucosal barrier in patients. We conducted complementary studies in animal models on the effects of FMT and BCT, and provide recommendations for improving the clinical outcomes of these treatments. To establish the dysbiosis model, male BALB/c mice were treated with ceftriaxone intra-gastrically for 7 days. After that, FMT and BCT were performed on ceftriaxone-treated mice for 3 consecutive days to rebuild the intestinal ecosystem. Post-FMT and post-BCT changes of the intestinal microbial community and mucosal barrier functions were investigated and compared. Disruption of intestinal microbial homeostasis impacted the integrity of mucosal epithelial layer, resulting in increased intestinal permeability. These outcomes were accompanied by overexpression of Muc2, significant decrease of SIgA secretion, and overproduction of defensins and inflammatory cytokines. After FMT and BCT, the intestinal microbiota recovered quickly, this was associated with better reconstruction of mucosal barriers and re-establishment of immune networks compared with spontaneous recovery (SR). Although based on a short-term study, our results suggest that FMT and BCT promote the re-establishment of intestinal microbial communities in mice with antibiotic-induced dysbiosis, and contribute to the temporal and spatial interactions between microbiota and mucosal barriers. The effects of BCT are comparable to that of FMT, especially in normalizing the intestinal levels of Muc2, SIgA, and defensins.

Anti-mouse CD52 monoclonal antibody ameliorates intestinal epithelial barrier function in interleukin-10 knockout mice with spontaneous chronic colitis

Intestinal inflammation causes tight junction changes and death of epithelial cells, and plays an important role in the development of Crohn's disease (CD). CD52 monoclonal antibody (CD52 mAb) directly targets the cell surface CD52 and is effective in depleting mature lymphocytes by cytolytic effects in vivo, leading to long-lasting changes in adaptive immunity. The aim of this study was to investigate the therapeutic effect of CD52 mAb on epithelial barrier function in animal models of IBD. Interleukin-10 knockout mice (IL-10(-/-) ) of 16 weeks with established colitis were treated with CD52 mAb once a week for 2 weeks. Severity of colitis, CD4(+) lymphocytes and cytokines in the lamina propria, epithelial expression of tight junction proteins, morphology of tight junctions, tumour necrosis factor-α (TNF-α)/TNF receptor 2 (TNFR2) mRNA expression, myosin light chain kinase (MLCK) expression and activity, as well as epithelial apoptosis in proximal colon were measured at the end of the experiment. CD52 mAb treatment effectively attenuated colitis associated with decreased lamina propria CD4(+) lymphocytes and interferon-γ/IL-17 responses in colonic mucosa in IL-10(-/-) mice. After CD52 mAb treatment, attenuation of colonic permeability, increased epithelial expression and correct localization of tight junction proteins (occludin and zona occludens protein-1), as well as ameliorated tight junction morphology were observed in IL-10(-/-) mice. CD52 mAb treatment also effectively suppressed the epithelial apoptosis, mucosa TNF-α mRNA expression, epithelial expression of long MLCK, TNFR2 and phosphorylation of MLC. Our results indicated that anti-CD52 therapy may inhibit TNF-α/TNFR2-mediated epithelial apoptosis and MLCK-dependent tight junction permeability by depleting activated T cells in the gut mucosa.