Commensals, bacterial pathogens and intestinal inflammation: an intriguing ménage à trois

The human colon: Evidence for degenerative changes during aging and the physiological consequences

BACKGROUND

The incidence of constipation increases among the elderly (>65 years), while abdominal pain decreases. Causes include changes in lifestyle (e.g., diet and reduced exercise), disease and medications affecting gastrointestinal functions. Degenerative changes may also occur within the colo-rectum. However, most evidence is from rodents, animals with relatively high rates of metabolism and accelerated aging, with considerable variation in time course. In humans, cellular and non-cellular changes in the aging intestine are poorly investigated.

PURPOSE

To examine all available studies which reported the effects of aging on cellular and tissue functions of human isolated colon, noting the region studied, sex and age of tissue donors and study size. The focus on human colon reflects the ability to access full-thickness tissue over a wide age range, compared with other gastrointestinal regions. Details are important because of natural human variability. We found age-related changes within the muscle, in the enteric and nociceptor innervation, and in the submucosa. Some involve all regions of colon, but the ascending colon appears more vulnerable. Changes can be cell- and sublayer-dependent. Mechanisms are unclear but may include development of "senescent-like" and associated inflammaging, perhaps associated with increased mucosal permeability to harmful luminal contents. In summary, reduced nociceptor innervation can explain diminished abdominal pain among the elderly. Degenerative changes within the colon wall may have little impact on symptoms and colonic functions, because of high "functional reserve," but are likely to facilitate the development of constipation during age-related challenges (e.g., lifestyle, disease, and medications), now operating against a reduced functional reserve.

Oral arsenite exposure induces inflammation and apoptosis in pulmonary tissue: acute and chronic evaluation in young and adult mice

Inorganic arsenic is a well-known environmental toxicant, and exposure to this metalloid is strongly linked with severe and extensive toxic effects in various organs including the lungs. In the present study, we aimed to investigate the acute and chronic effects of arsenite exposure on pulmonary tissue in young and adult mice. In brief, young and adult female Balb/C mice were exposed to 3 and 30 ppm arsenite daily via drinking water for 30 and 90 days. Subsequently, the animals were sacrificed and various histological and immunohistochemistry (IHC) analyses were performed using lung tissues. Our findings showed arsenite was found to cause dose-dependent pathological changes such as thickening of the alveolar septum, inflammatory cell infiltrations and lung fibrosis in young and adult mice. In addition, arsenite exposure significantly increased the expression of inflammatory markers NF-κB and TNF-α, indicating that arsenite-exposed mice suffered from severe lung inflammation. Moreover, the IHC analysis of fibrotic proteins demonstrated an increased expression of TGF-β1, α-SMA, vimentin and collagen-I in the arsenite-exposed mice compared to the control mice. This was accompanied by apoptosis, which was indicated by the upregulated expression of caspase-3 in arsenite-exposed mice compared to the control. Adult mice were generally found to be more prone to arsenite toxicity during chronic exposure relative to their younger counterparts. Overall, our findings suggest that arsenite in drinking water may induce dose-dependent and age-dependent structural and functional impairment in the lungs through elevating inflammation and fibrotic proteins.

Chemotherapy-Induced Changes in Plasma Amino Acids and Lipid Oxidation of Resected Patients with Colorectal Cancer: A Background for Future Studies

Previous studies have documented that FOLFOX and XELOX therapies negatively impact the metabolism of skeletal muscle and extra-muscle districts. This pilot study tested whether three-month FOLFOX or XELOX therapy produced changes in plasma amino acid levels (PAAL) (an estimation of whole-body amino acid metabolism) and in plasma levels of malondialdehyde (MDA), a marker of lipid hyper oxidation. Fourteen ambulatory, resected patients with colorectal cancer scheduled to receive FOLFOX (n = 9) or XELOX (n = 5) therapy, after overnight fasting, underwent peripheral venous blood sampling, to determine PAAL and MDA before, during, and at the end of three-month therapy. Fifteen healthy matched subjects (controls) only underwent measures of PAAL at baseline. The results showed changes in 87.5% of plasma essential amino acids (EAAs) and 38.4% of non-EAAs in patients treated with FOLFOX or XELOX. These changes in EAAs occurred in two opposite directions: EAAs decreased with FOLFOX and increased or did not decrease with XELOX (interactions: from p = 0.034 to p = 0.003). Baseline plasma MDA levels in both FOLFOX and XELOX patients were above the normal range of values, and increased, albeit not significantly, during therapy. In conclusion, three-month FOLFOX or XELOX therapy affected plasma EAAs differently but not the baseline MDA levels, which were already high.

Role of Maternal Antibodies in the Protection of Broiler Chicks against Campylobacter Colonization in the First Weeks of Life

Thermophilic Campylobacter species are the most common cause of bacterium-mediated diarrheal disease in humans globally. Poultry is considered the most important reservoir of human campylobacteriosis, but so far, no effective countermeasures are in place to prevent the bacterium from colonizing broiler flocks. This study investigated maternal antibodies' potential to offer protection against Campylobacter in broiler chicks via a field trial and an immunization trial. In the field trial, breeder flocks with high and low anti-Campylobacter antibody levels in the yolk were selected based on serological screening. Offspring were subsequently monitored for maternal antibodies and Campylobacter prevalence during early life. Although maternal antibodies declined rapidly in the serum of broilers, offspring from flocks with lower anti-Campylobacter antibody levels seemed to be more susceptible to colonization. In the immunization trial, breeders from a seropositive breeder flock were vaccinated with an experimental bacterin or subunit vaccine. Immunization increased antibody levels in the yolk and consequently in the offspring. Elevated maternal antibody levels were significantly associated with reduced Campylobacter susceptibility in broilers at 2 weeks old but not at 1 and 3 weeks old. Overall, the protective effect of maternal immunity should be cautiously considered in the context of Campylobacter control in broilers. Immunization of breeders may enhance resistance but is not a comprehensive solution.

Evaluation of Rouxiella badensis Subsp Acadiensis (Canan SV-53) as a Potential Probiotic Bacterium

The advent of omic platforms revealed the significant benefits of probiotics in the prevention of many infectious diseases. This led to a growing interest in novel strains of probiotics endowed with health characteristics related to microbiome and immune modulation. Therefore, autochthonous bacteria in plant ecosystems might offer a good source for novel next-generation probiotics. The main objective of this study was to analyze the effect of Rouxiella badensis acadiensis Canan (R. acadiensis) a bacterium isolated from the blueberry biota, on the mammalian intestinal ecosystem and its potential as a probiotic microorganism. R. acadiensis, reinforced the intestinal epithelial barrier avoiding bacterial translocation from the gut to deep tissues, even after feeding BALB/c mice for a prolonged period of time. Moreover, diet supplementation with R. acadiensis led to increases in the number of Paneth cells, well as an increase in the antimicrobial peptide α defensin. The anti-bacterial effect of R. acadiensis against Staphylococcus aureus and Salmonella enterica serovar Typhimurium was also reported. Importantly, R. acadiensis-fed animals showed better survival in an in vivo Salmonella enterica serovar Typhimurium challenge compared with those that received a conventional diet. These results demonstrated that R. acadiensis possesses characteristics of a probiotic strain by contributing to the reinforcement and maintenance of intestinal homeostasis.

Apolipoprotein ɛ4-Associated Protection Against Pediatric Enteric Infections is a Survival Advantage in Pre-Industrial Populations

Until 300,000 years ago, ancestors of modern humans ubiquitously carried the apolipoprotein E (APOE) ɛ4/ɛ4 genotype, when the ɛ3 allele mutated from the ancestral ɛ4, which elevates the risk of Alzheimer's disease. Modern humans living today predominantly carry the ɛ3 allele, which provides protection against heart disease and dementia in long-lived populations. The ancestral ɛ4 allele has been highly preserved in isolated populations in tropical and Arctic regions with high pathogen burdens, e.g., helminths. Early humans experienced serious enteric infections that exerted evolutionary selection pressure, and factors that mitigate infant and childhood mortality from enteric infections also exert selection pressure. Some bacteria can exploit the host's defensive inflammatory response to colonize and invade the host. Pathogen-induced inflammation associated with infant and childhood diarrhea can damage the gut wall long after the invading organisms are no longer present. Inflammation not only resides in the mucosal wall, but also induces systemic inflammation. Baseline systemic inflammation is lower in ɛ4 carriers, yet ɛ4 carriers display a stronger host inflammatory response that reduces pathogen burdens, increasing infant and early childhood survival. Evolutionary selection of the ɛ3 allele likely occurred after humans moved into temperate zones with lower pathogen burdens, unrelated to protection from Alzheimer's disease.

Human skin through the ages

As the largest organ of the human body the skin offers a protective role, providing a tough but pliable covering that provides the major barrier between the internal organs and the environment. It actively regulates water loss and is both oxygen and carbon dioxide permeable, and influences temperature regulation and immunological functions through its sensory properties. Both intrinsic and enhanced environmental factors contribute to the progressive deterioration of the skin with increasing age. Cutaneous problems are therefore an unavoidable and inevitable consequence of aging skin, which can prove to be both cosmetically unacceptable to those who succumb to these problems, as well as even life threatening if skin breakdown becomes chronic as is case with leg ulceration. This in turn has major implications for long-term impact on those looking after them (e.g., family, carers, etc.) and a huge burden on the health care system.

Resilience and the Gut Microbiome: Insights from Chronically Socially Stressed Wild-Type Mice

The microbiome is an important player within physiological homeostasis of the body but also in pathophysiological derailments. Chronic social stress is a challenge to the organism, which results in psychological illnesses such as depression in some individuals and can be counterbalanced by others, namely resilient individuals. In this study, we wanted to elucidate the potential contribution of the microbiome to promote resilience. Male mice were subjected to the classical chronic social defeat paradigm. Defeated or undefeated mice were either controls (receiving normal drinking water) or pre-treated with antibiotics or probiotics. Following social defeat, resilient behavior was assessed by means of the social interaction test. Neither depletion nor probiotic-shifted alteration of the microbiome influenced stress-associated behavioral outcomes. Nevertheless, clear changes in microbiota composition due to the defeat stress were observed such as elevated Bacteroides spp. This stress-induced increase in Bacteroides in male mice could be confirmed in a related social stress paradigm (instable social hierarchy) in females. This indicates that while manipulation of the microbiome via the antibiotics- and probiotics-treatment regime used here has no direct impact on modulating individual stress susceptibility in rodents, it clearly affects the microbiome in the second line and in a sex-independent manner regarding Bacteroides.

Impact of the Age of Cecal Material Transfer Donors on Alzheimer’s Disease Pathology in 5xFAD Mice

Alzheimer’s disease is a progressive neurodegenerative disorder affecting around 30 million patients worldwide. The predominant sporadic variant remains enigmatic as the underlying cause has still not been identified. Since efficient therapeutic treatments are still lacking, the microbiome and its manipulation have been considered as a new, innovative approach. 5xFAD Alzheimer’s disease model mice were subjected to one-time fecal material transfer after antibiotics-treatment using two types of inoculation: material derived from the caecum of age-matched (young) wild type mice or from middle aged, 1 year old (old) wild type mice. Mice were profiled after transfer for physiological parameters, microbiome, behavioral tasks, and amyloid deposition. A single time transfer of cecal material from the older donor group established an aged phenotype in the recipient animals as indicated by elevated cultivatable fecal Enterobacteriaceae and Lactobacillaceae representative bacteria, a decreased Firmicutes amount as assessed by qPCR, and by increased levels of serum LPS binding protein. While behavioral deficits were not accelerated, single brain regions (prefrontal cortex and dentate gyrus) showed higher plaque load after transfer of material from older animals. We could demonstrate that the age of the donor of cecal material might affect early pathological hallmarks of Alzheimer’s disease. This could be relevant when considering new microbiome-based therapies for this devastating disorder.

Probiotic therapy in patients with irritable bowel syndrome: does it have a real role?

Background

Irritable bowel syndrome (IBS) is one of the most prevalent functional gastrointestinal disorders (FGIDs). There is good evidence that microbiota plays a predominant role in the IBS pathophysiology. The aim of the study is to evaluate the role of probiotics in improvement of IBS symptoms via IBS-symptom severity scale (IBS-SSS Arabic version) and improvement of quality of life via irritable bowel syndrome-quality of life survey (IBS-QOL).

Results

This double-armed comparative trial was conducted on IBS patients, who fulfill ROME IV criteria and the IBS diagnostic questionnaire between August and December 2019. Ninety patients were followed up for 4 weeks from the first visit. The first group was prescribed probiotics (10 billion colony of Lactobacillus delbruekii and Lactobacillus fermentum) and itopride hcl 50 mg three times daily, while the second group received only itopride hcl 50 mg by the same dose for 4 weeks. There was a highly significant improvement in the IBS-SSS score in group 1 after 4 weeks of treatment than in group 2 (137.56±67.53 vs 258.44±34.18) (p=0.001). Also, there was a highly significant improvement in the overall QOL terms in group 1 in comparison with baseline QOL score [with overall mean score (60.64±7.77) at baseline vs (81.54±7.87) at 4 weeks (p value <0.001)].

Conclusion

Probiotics are useful for the improvement of IBS symptoms and quality of life of the studied patients. Larger multicenter studies are needed in the future.

The Impacts of Short-Term NMN Supplementation on Serum Metabolism, Fecal Microbiota, and Telomere Length in Pre-Aging Phase

Aging is a natural process with concomitant changes in the gut microbiota and associate metabolomes. Beta-nicotinamide mononucleotide, an important NAD+ intermediate, has drawn increasing attention to retard the aging process. We probed the changes in the fecal microbiota and metabolomes of pre-aging male mice (C57BL/6, age: 16 months) following the oral short-term administration of nicotinamide mononucleotide (NMN). Considering the telomere length as a molecular gauge for aging, we measured this in the peripheral blood mononuclear cells (PBMC) of pre-aging mice and human volunteers (age: 45-60 years old). Notably, the NMN administration did not influence the body weight and feed intake significantly during the 40 days in pre-aging mice. Metabolomics suggested 266 upregulated and 58 downregulated serum metabolites. We identified 34 potential biomarkers linked with the nicotinamide, purine, and proline metabolism pathways. Nicotinamide mononucleotide significantly reduced the fecal bacterial diversity (p < 0.05) with the increased abundance of Helicobacter, Mucispirillum, and Faecalibacterium, and lowered Akkermansia abundance associated with nicotinamide metabolism. We propose that this reshaped microbiota considerably lowered the predicated functions of aging with improved immune and cofactors/vitamin metabolism. Most notably, the telomere length of PBMC was significantly elongated in the NMN-administered mice and humans. Taken together, these findings suggest that oral NMN supplementation in the pre-aging stage might be an effective strategy to retard aging. We recommend further studies to unravel the underlying molecular mechanisms and comprehensive clinical trials to validate the effects of NMN on aging.

Toll Like Receptors as Sensors of the Tumor Microbial Dysbiosis: Implications in Cancer Progression

The microbiota is a complex ecosystem of active microorganisms resident in the body of mammals. Although the majority of these microorganisms resides in the distal gastrointestinal tract, high-throughput DNA sequencing technology has made possible to understand that several other tissues of the human body host their own microbiota, even those once considered sterile, such as lung tissue. These bacterial communities have important functions in maintaining a healthy body state, preserving symbiosis with the host immune system, which generates protective responses against pathogens and regulatory pathways that sustain the tolerance to commensal microbes. Toll-like receptors (TLRs) are critical in sensing the microbiota, maintaining the tolerance or triggering an immune response through the direct recognition of ligands derived from commensal microbiota or pathogenic microbes. Lately, it has been highlighted that the resident microbiota influences the initiation and development of cancer and its response to therapies and that specific changes in the number and distribution of taxa correlate with the existence of cancers in various tissues. However, the knowledge of functional activity and the meaning of microbiome changes remain limited. This review summarizes the current findings on the function of TLRs as sensors of the microbiota and highlighted their modulation as a reflection of tumor-associated changes in commensal microbiota. The data available to date suggest that commensal "onco-microbes" might be able to break the tolerance of TLRs and become complicit in cancer by sustaining its growth.

Uncovering the pathophysiology of irritable bowel syndrome by exploring the gut-brain axis: a narrative review

Objective

To improve the pathophysiological understanding of irritable bowel syndrome (IBS) by exploring the gut-brain axis.

Background

Disorders of gut-brain interaction (DGBIs) are gastrointestinal (GI) disorders in which alterations in bowel functions occur. IBS, which is one of the most studied DGBIs, is linked with abdominal distress or pain without obvious structural or biochemical anomalies.

Methods

The etiology of IBS has not been clearly described but is known to be multifactorial, involving GI motility changes, post-infectious reactivity, visceral hypersensitivity, gut-brain interactions, microbiota dysbiosis, small intestinal bacterial overgrowth, food sensitivity, carbohydrate malabsorption, and intestinal inflammation.

Conclusions

One of the main features of IBS is the occurrence of structural and functional disruptions in the gut-brain axis, which alter reflective and perceptual nervous system reactions. Herein, we provide a brief summary of this topic. Furthermore, we discuss animal models, which are important in the study of IBS, especially as it is linked with stressors. These animal models cannot fully represent the human disease but serve as important tools for understanding this complicated disorder. In the future, technologies, such as organ-on-a-chip models and metabolomics, will provide novel information regarding the pathophysiology of IBS, which will play an important role in treatment development. Finally, we take a brief glance at how acupuncture treatments may hold potential for patients with IBS.

Influence of innate immune activation on endocrine and metabolic pathways in infancy

Prematurity is the leading cause of neonatal morbidity and mortality worldwide. Premature infants often require extended hospital stays, with increased risk of developing infection compared with term infants. A picture is emerging of wide-ranging deleterious consequences resulting from innate immune system activation in the newborn infant. Those who survive infection have been exposed to a stimulus that can impose long-lasting alterations into later life. In this review, we discuss sepsis-driven alterations in integrated neuroendocrine and metabolic pathways and highlight current knowledge gaps in respect of neonatal sepsis. We review established biomarkers for sepsis and extend the discussion to examine emerging findings from human and animal models of neonatal sepsis that propose novel biomarkers for early identification of sepsis. Future research in this area is required to establish a greater understanding of the distinct neonatal signature of early and late-stage infection, to improve diagnosis, curtail inappropriate antibiotic use, and promote precision medicine through a biomarker-guided empirical and adjunctive treatment approach for neonatal sepsis. There is an unmet clinical need to decrease sepsis-induced morbidity in neonates, to limit and prevent adverse consequences in later life and decrease mortality.

Acceleration of Small Intestine Development and Remodeling of the Microbiome Following Hyaluronan 35 kDa Treatment in Neonatal Mice

The beneficial effects of human milk suppressing the development of intestinal pathologies such as necrotizing enterocolitis in preterm infants are widely known. Human milk (HM) is rich in a multitude of bioactive factors that play major roles in promoting postnatal maturation, differentiation, and the development of the microbiome. Previous studies showed that HM is rich in hyaluronan (HA) especially in colostrum and early milk. This study aims to determine the role of HA 35 KDa, a HM HA mimic, on intestinal proliferation, differentiation, and the development of the intestinal microbiome. We show that oral HA 35 KDa supplementation for 7 days in mouse pups leads to increased villus length and crypt depth, and increased goblet and Paneth cells, compared to controls. We also show that HA 35 KDa leads to an increased predominance of Clostridiales Ruminococcaceae, Lactobacillales Lactobacillaceae, and Clostridiales Lachnospiraceae. In seeking the mechanisms involved in the changes, bulk RNA seq was performed on samples from the terminal ileum and identified upregulation in several genes essential for cellular growth, proliferation, and survival. Taken together, this study shows that HA 35 KDa supplemented to mouse pups promotes intestinal epithelial cell proliferation, as well as the development of Paneth cells and goblet cell subsets. HA 35 KDa also impacted the intestinal microbiota; the implications of these responses need to be determined.

Location-specific cell identity rather than exposure to GI microbiota defines many innate immune signalling cascades in the gut epithelium

OBJECTIVE

The epithelial layer of the GI tract is equipped with innate immune receptors to sense invading pathogens. Dysregulation in innate immune signalling pathways is associated with severe inflammatory diseases, but the responsiveness of GI epithelial cells to bacterial stimulation remains unclear.

DESIGN

We generated 42 lines of human and murine organoids from gastric and intestinal segments of both adult and fetal tissues. Genome-wide RNA-seq of the organoids provides an expression atlas of the GI epithelium. The innate immune response in epithelial cells was assessed using several functional assays in organoids and two-dimensional monolayers of cells from organoids.

RESULTS

Results demonstrate extensive spatial organisation of innate immune signalling components along the cephalocaudal axis. A large part of this organisation is determined before birth and independent of exposure to commensal gut microbiota. Spatially restricted expression of Toll-like receptor 4 (Tlr4) in stomach and colon, but not in small intestine, is matched by nuclear factor kappa B (NF-κB) responses to lipopolysaccharide (LPS) exposure. Gastric epithelial organoids can sense LPS from the basal as well as from the apical side.

CONCLUSION

We conclude that the epithelial innate immune barrier follows a specific pattern per GI segment. The majority of the expression patterns and the function of TLR4 is encoded in the tissue-resident stem cells and determined primarily during development.

Gastrointestinal epithelial innate immunity-regionalization and organoids as new model

The human gastrointestinal tract is in constant contact with microbial stimuli. Its barriers have to ensure co-existence with the commensal bacteria, while enabling surveillance of intruding pathogens. At the centre of the interaction lies the epithelial layer, which marks the boundaries of the body. It is equipped with a multitude of different innate immune sensors, such as Toll-like receptors, to mount inflammatory responses to microbes. Dysfunction of this intricate system results in inflammation-associated pathologies, such as inflammatory bowel disease. However, the complexity of the cellular interactions, their molecular basis and their development remains poorly understood. In recent years, stem cell-derived organoids have gained increasing attention as promising models for both development and a broad range of pathologies, including infectious diseases. In addition, organoids enable the study of epithelial innate immunity in vitro. In this review, we focus on the gastrointestinal epithelial barrier and its regional organization to discuss innate immune sensing and development.

Pharmacological Therapies and Their Clinical Targets in Irritable Bowel Syndrome With Diarrhea

Irritable bowel syndrome (IBS) is one of the most common disorders of the gut-brain axis, which affects approximately 4% of the global population. The Rome IV criteria define IBS as chronic or recurrent abdominal pain associated with altered bowel habits. Patients can be categorized in four subtypes: IBS with predominant constipation (IBS-C), predominant diarrhea (IBS-D), mixed bowel habits (IBS-M), and unclassified (IBS-U). IBS is associated with a lower quality of life, reduced work productivity, and high healthcare costs. When comparing subtypes, patients with IBS-D report lower disease related quality of life. Due to the scope of this review, we have solely focused on patients with IBS-D. Choosing the right pharmacological treatment in these patients remains challenging due to the heterogeneous patient population, patients' expectation of the treatment outcome, unavailability of efficacious drugs, and the multifactorial and incompletely understood underlying pathophysiology. Currently, pharmacological treatment options target individual symptoms, such as abdominal pain, altered bowel habits, and bloating. In this review, we aimed to summarize the current and recent pharmacological treatment options in IBS-D, targeting the predominant gastrointestinal symptoms. Additionally, we proposed a pharmacological treatment algorithm which healthcare professionals could use when treating individual patients with IBS-D.

EpiMix Based Novel Vaccine Candidate for Shigella: Evidence of Prophylactic Immunity in Balb/c Mice

Multidrug resistant Shigella is one of the leading causes of mortality in children and infants. Availability of vaccine could prevent the Shigella infection and reduce the mortality. Conventional approaches of vaccine development against shigellosis have not resulted in desirable vaccine. As shigellosis may be caused by multiple strains and serotypes, there is a need to develop a multivalent vaccine, capable of providing protection against multiple Shigella strains. To develop broad spectrum vaccine, we had previously derived a pool of conserved epitopes against Shigella by using multiple immunoinformatic tools. In this study, the identified conserved epitopes derived from the Outer Membrane Proteins A and C of Shigella were chemically synthesized, and the EpiMix made up of 5 epitopes coupled to a carrier protein, ovalbumin was developed and validated for its immunogenicity. The intramuscular immunization with EpiMix in Balb/c mice led to increase in EpiMix specific serum IgG, and significant increase in fecal IgA as well as in IL-4, IL-2and IFN-γ levels. Further, the EpiMix immunized mice showed protection when challenged against S. flexneri ATCC 12022 using the intraperitoneal route. Moreover, the analysis of cytokine profile and IFN-γ/IL4 ratio in post Shigella challenge immunized mice suggested the high levels of IFN-γ levels and possible dominance of Th1 response, playing pivotal role in the elimination of Shigella. Collectively, the results demonstrate the immunogenic potential and protective efficacy of the EpiMix in the murine shigellosis model. However, the detailed study and further optimisation of epitopes would substantiate the prospective use of EpiMix as a prophylactic candidate for vaccination.

Influence of Prebiotic Activity of Agave salmiana Fructans on Mucus Production and Morphology Changes in Colonic Epithelium Cell of Healthy Wistar Rats

The beneficial health of evaluating prebiotic effect by the consumption of Agave salmiana fructans (A. salmiana fructans) was assessed in the epithelium of the cecum and proximal colon of Wistar rats fed at different doses for 35 days with regards to mucus production, morphological cell changes, and the serum concentration of tumor necrosis factor-α (TNF-α). Results showed a significant increase in mucus-secreting cells (P < 0.05) and a normal structure with preserved crypts, without morphological damage to colonic cells for a dose of 12.5% (w/w) with respect to the control and the other doses evaluated. The concentration of pro-inflammatory cytokine TNF-α was decreased significantly (P < 0.05) in the groups with doses of 10 and 12.5% (w/w) at 7 and 35 days, respectively. This effect was positively correlated with the reduction of inflammation in epithelial cells. This study provides direct evidence of the effects of the A. salmiana fructans on the colonic epithelium, demonstrating that a diet supplemented with 12.5% of fructans for 35 days exerts health benefits through the strengthening of the mucosa layer, which favors the adherence of the bacterial population and suppresses inflammation.

Rapamycin and MCC950 modified gut microbiota in experimental autoimmune encephalomyelitis mouse by brain gut axis

AIMS

Multiple sclerosis (MS) whose pathogenesis is still unclear is a chronic progressive disease in the central nervous system. Gut microbiota can directly or indirectly affect the immune system through the brain gut axis to engage in the occurrence and development of the disease.

MATERIALS AND METHODS

C57BL/6 mice which were immunized by MOG_35-55 to prepare experimental autoimmune encephalomyelitis (EAE) animal models were treated with rapamycin and MCC950 (CP-456773) in combination or separately. After sequencing the 16S rRNA V4 region of gut microbiota, the species, abundance and composition of gut microbiota were analyzed by Alpha diversity, Bata diversity and LEfSe analysis. The pathological changes and the expression of CD4 and CD8 of brain, large intestine and spleen were detected.

KEY FINDINGS

The results showed that rapamycin and MCC950 could alleviate the progression of the disease by inducing autophagy and inhibiting the immune response. The Alpha diversity of EAE model group was no significant difference compering to control group while the number of OTUs was decreased. After the treatment by rapamycin and MCC950, the abundance and composition of gut microbiota was relatively recovered, which was close to that of normal mice.

SIGNIFICANCE

Inhibiting immune cell-mediated inflammation and restoring the composition of gut microbiota may help to alleviate the clinical symptoms of multiple sclerosis. Furthermore, to research the regulatory effect between immune response and gut microbiota may be a new strategy for the prevention and treatment of multiple sclerosis.

The Microbiota-Gut-Brain Axis Heart Shunt Part I: The French Paradox, Heart Disease and the Microbiota

It has been well established that a vegetarian and polyphenol-rich diet, including fruits, vegetables, teas, juices, wine, indigestible fiber and whole grains, provide health-promoting phytochemicals and phytonutrients that are beneficial for the heart and brain. What is not well-characterized is the affect these foods have when co-metabolized within our dynamic gut and its colonizing flora. The concept of a heart shunt within the microbiota-gut-brain axis underscores the close association between brain and heart health and the so-called “French paradox” offers clues for understanding neurodegenerative and cerebrovascular diseases. Moreover, oxidation-redox reactions and redox properties of so-called brain and heart-protective foods are underappreciated as to their enhanced or deleterious mechanisms of action. Focusing on prodromal stages, and common mechanisms underlying heart, cerebrovascular and neurodegenerative diseases, we may unmask and understanding the means to better treat these related diseases.

The connection between microbiome and schizophrenia

There has been an accumulation of knowledge about the human microbiome, some detailed investigations of the gastrointestinal microbiota and its functions, and the highlighting of complex interactions between the gut, the gut microbiota, and the central nervous system. That assumes the involvement of the microbiome in the pathogenesis of various CNS diseases, including schizophrenia. Given this information and the fact, that the gut microbiota is sensitive to internal and environmental influences, we have speculated that among the factors that influence the formation and composition of gut microbiota during life, possible key elements in the schizophrenia development chain are hidden where gut microbiota is a linking component. This article aims to describe and understand the developmental relationships between intestinal microbiota and the risk of developing schizophrenia.

Gut microbiota combined with metabolomics reveals the metabolic profile of the normal aging process and the anti-aging effect of FuFang Zhenshu TiaoZhi(FTZ) in mice

The aging process is accompanied by changes in the gut microbiota and metabolites. This study aimed to reveal the relationship between gut microbiota and the metabolome at different ages, as well as the anti-aging effect of FTZ, which is an effective clinical prescription for the treatment of hyperlipidemia and diabetes.

METHODS

In the present study, mice were randomly divided into different age and FTZ treatment groups. The aging-relevant behavioral phenotype the levels of blood glucose, cholesterol, triglycerides, low density lipoprotein cholesterol, free fatty acids, high density lipoprotein-cholesterol and cytokine TNF-α,IL-6, IL-8 in the serum were measured. Changes of serum metabolties were analyzed by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-Q-TOF/MS). Gut microbiota were identified using 16S rDNA sequencing.

RESULTS

Our results indicated that with age, the aging-relevant behavioral phenotype appeared, glucose and lipid metabolism disordered, secretion levels of cytokine TNF-α, IL-6 and IL-8 increased.The Firmicutes/Bacteroidetes ratio changed with age, first increasing and then decreasing, and the microbial diversity and the community richness of the aging mice were improved by FTZ. The abundance of opportunistic bacteria decreased (Lactobacillus murinus, Erysipelatoclostridium), while the levels of protective bacteria such as Butyricimonas, Clostridium and Akkermansia increased. Metabolic analysis identified 24 potential biomarkers and 10 key pathways involving arachidonic acid metabolism, phospholipid metabolism, fatty acid metabolism, taurine and hypotaurine metabolism. Correlation analysis between the gut microbiota and biomarkers suggested that the relative abundance of protective bacteria was negatively correlated with the levels of leukotriene E4, 20-HETE and arachidonic acid, which was different from protective bacteria.

CONCLUSION

Shifts of gut microbiota and metabolomic profiles were observed in the mice during the normal aging process, and treatment with FTZ moderately corrected the aging, which may be mediated via interference with arachidonic acid metabolism, sphingolipid metabolism, glycerophospholipid metabolism, taurine and hypotaurine metabolism and gut microbiota in mice.

Microbiology and immunology: An ideal partnership for a tango at the gut surface-A tribute to Philippe Sansonetti

Over the past 20 years, the highly dynamic interactions that take place between hosts and the gut microbiota have emerged as a major determinant in health and disease. The complexity of the gut microbiota represents, however, a considerable challenge, and reductionist approaches are indispensable to define the contribution of individual bacteria to host responses and to dissect molecular mechanisms. In this tribute to Philippe Sansonetti, I would like to show how rewarding collaborations with microbiologists have guided our team of immunologists in the study of host–microbiota interactions and, thanks to the use of controlled colonisation experiments in gnotobiotic mice, toward the demonstration that segmented filamentous bacteria (SFB) are indispensable to drive the post‐natal maturation of the gut immune barrier in mice. The work led with Philippe Sansonetti to set up in vitro culture conditions has been one important milestone that laid the ground for in‐depth characterization of the molecular attributes of this unusual symbiont. Recent suggestions that SFB may be present in the human microbiota encourage further cross‐fertilising interactions between microbiologists and immunologists to define whether results from mice can be translated to humans and, if so, how SFB may be used to promote human intestinal defences against enteropathogens. Nurturing the competences to pursue this inspiring project is one legacy of Philippe Sansonetti.

The Microbiome and Irritable Bowel Syndrome - A Review on the Pathophysiology, Current Research and Future Therapy

Irritable bowel syndrome (IBS) is a functional disorder which affects a large proportion of the population globally. The precise etiology of IBS is still unknown, although consensus understanding proposes IBS to be of multifactorial origin with yet undefined subtypes. Genetic and epigenetic factors, stress-related nervous and endocrine systems, immune dysregulation and the brain-gut axis seem to be contributing factors that predispose individuals to IBS. In addition to food hypersensitivity, toxins and adverse life events, chronic infections and dysbiotic gut microbiota have been suggested to trigger IBS symptoms in tandem with the predisposing factors. This review will summarize the pathophysiology of IBS and the role of gut microbiota in relation to IBS. Current methodologies for microbiome studies in IBS such as genome sequencing, metagenomics, culturomics and animal models will be discussed. The myriad of therapy options such as immunoglobulins (immune-based therapy), probiotics and prebiotics, dietary modifications including FODMAP restriction diet and gluten-free diet, as well as fecal transplantation will be reviewed. Finally this review will highlight future directions in IBS therapy research, including identification of new molecular targets, application of 3-D gut model, gut-on-a-chip and personalized therapy.

Impact of high-grain diet feeding on mucosa-associated bacterial community and gene expression of tight junction proteins in the small intestine of goats

The objective of this study was to investigate the impact of a high‐grain (HG) diet on the microbial fermentation, the composition of the mucosa‐associated bacterial microbiota, and the gene expression of tight junction proteins in the small intestine of goats. In the present study, we randomly assigned 10 male goats to either a hay diet (n = 5) or a HG diet (56.5% grain; n = 5) and then examined changes in the bacterial community using Illumina MiSeq sequencing and the expression of tight junction proteins using qRT‐PCR in the mucosa of the small intestine. The results showed that HG diet decreased the luminal pH (p = 0.005) and increased the lipopolysaccharide content (p < 0.001) in the digesta of the ileum, and it increased the concentration of total volatile fatty acids in the digesta of the jejunum (p = 0.015) and ileum (p = 0.007) compared with the hay diet. MiSeq sequencing results indicated that the HG diet increased (FDR = 0.007–0.028) the percentage of the genera Stenotrophomonas, Moraxella, Lactobacillus, and Prevotella in jejunal mucosa but decreased (FDR = 0.016) the abundance of Christensenellaceae R7 group in the ileal mucosa compared with the hay diet. Furthermore, the HG diet caused downregulation of the mRNA expression of claudin‐4, occludin, and ZO‐1 in jejunal and ileal mucosa (p < 0.05). Collectively, our data suggested that the HG diet induced changes in the relative abundance of some mucosa‐associated bacteria, in addition to downregulation of the mRNA expression of tight junction proteins in the small intestine. These findings provide new insights into the adaptation response of the small intestine to HG feeding in ruminants.

The Microbiome: A New Target for Research and Treatment of Schizophrenia and its Resistant Presentations? A Systematic Literature Search and Review

Background: The gastrointestinal system hosts roughly 1,800 distinct phyla and about 40,000 bacterial classes, which are known as microbiota, and which are able to influence the brain. For instance, microbiota can also influence the immune response through the activation of the immune system or through the release of mediators that are able to cross the brain blood barrier or that can interact with other substances that have free access to the brain, such as tryptophan and kynurenic acid, which is a metabolite of tryptophan and which has been involved in the pathogenesis of schizophrenia. Objectives: This paper reviews the possible relationships between microbiome, schizophrenia and treatment resistance. Given the possibility of a role of immune activation and alterations, we also describe the relationship between schizophrenia and immune inflammatory response. Finally, we report on the studies about the use of probiotic and prebiotics in schizophrenia. Methods: Cochrane library and PubMed were searched from the year 2000 to 2018 for publications about microbiome, immune-mediated pathology, schizophrenia and neurodevelopmental disorders. The following search string was used: (microbiome or immune mediated) AND (schizophrenia OR neurodevelopmental disorder). Associated publications were hand-searched from the list of references of the identified papers. A narrative review was also conducted about the use of probiotics and prebiotics in schizophrenia. Results: There exists a close relationship between the central nervous system and the gastrointestinal tract, which makes it likely that there is a relationship between schizophrenia, including its resistant forms, and microbiota. This paper provides a summary of the most important studies that we identified on the topic. Conclusions: Schizophrenia in particular, remain a challenge for researchers and practitioners and the possibility of a role of the microbiome and of immune-mediated pathology should be better explored, not only in animal models but also in clinical trials of agents that are able to alter gut microbiota and possibly influence the mechanisms of gastrointestinal inflammation. Microbiome targeted treatments have not been well-studied yet in patients with mental illness in general, and with schizophrenia in particular. Nonetheless, the field is well worth of being appropriately investigated.

The TLR9 agonist MGN1703 triggers a potent type I interferon response in the sigmoid colon

Toll-like receptor 9 (TLR9) agonists are being developed for treatment of colorectal and other cancers, yet the impact of these drugs on human intestines remains unknown. This, together with the fact that there are additional potential indications for TLR9 agonist therapy (e.g., autoimmune and infectious diseases), led us to investigate the impact of MGN1703 (Lefitolimod) on intestinal homeostasis and viral persistence in HIV-positive individuals. Colonic sigmoid biopsies were collected (baseline and week four) from 11 HIV+ individuals on suppressive antiretroviral therapy, who received MGN1703 (60 mg s.c.) twice weekly for 4 weeks in a single-arm, phase 1b/2a study. Within sigmoid mucosa, global transcriptomic analyses revealed 248 modulated genes (false discovery rate<0.05) including many type I interferon (IFN)-stimulated genes. MGN1703 increased the frequencies of cells exhibiting MX1 (P=0.001) and ISG15 (P=0.014) protein expression. No changes were observed in neutrophil infiltration (myeloperoxidase; P=0.97). No systematic effect on fecal microbiota structure was observed (analysis of similarity Global R=-0.105; P=0.929). TLR9 expression at baseline was inversely proportional to the change in integrated HIV DNA during MGN1703 treatment (P=0.020). In conclusion, MGN1703 induced a potent type I IFN response, without a concomitant general inflammatory response, in the intestines.

Harnessing Gut Microbes for Mental Health: Getting From Here to There

There has been an explosion of interest in the study of microorganisms inhabiting the gastrointestinal tract (gut microbiota) and their impact on host health and physiology. Accumulating data suggest that altered communication between gut microbiota and host systems could participate in disorders such as obesity, diabetes mellitus, and autoimmune disorders as well as neuropsychiatric disorders, including autism, anxiety, and major depressive disorders. The conceptual development of the microbiome-gut-brain axis has facilitated understanding of the complex and bidirectional networks between gastrointestinal microbiota and their host, highlighting potential mechanisms through which this environment influences central nervous system physiology. Communication pathways between gut microbiota and the central nervous system could include autonomic, neuroendocrine, enteric, and immune systems, with pathology resulting in disruption to neurotransmitter balance, increases in chronic inflammation, or exacerbated hypothalamic-pituitary-adrenal axis activity. However, uncertainty remains regarding the generalizability of controlled animal studies to the more multifaceted pattern of human pathophysiology, especially with regard to the therapeutic potential for neuropsychiatric health. This narrative review summarizes current understanding of gut microbial influence over physiological function, with an emphasis on neurobehavioral and neurological impairment based on growing understanding of the gut-brain axis. Experimental and clinical data regarding means of therapeutic manipulation of gut microbiota as a novel treatment option for mental health are described, and important knowledge gaps are identified and discussed.

The roles of antimicrobial peptide, rip-thanatin, in the midgut of Riptortus pedestris

Recently, we have reported the structural determination of antimicrobial peptides (AMPs), such as riptocin, rip-defensin, and rip-thanatin, from Riptortus pedestris. However, the biological roles of AMPs in the host midgut remain elusive. Here, we compared the expression levels of AMP genes in apo-symbiotic insects with those of symbiotic insects. Interestingly, the expression level of rip-thanatin was only significantly increased in the posterior midgut region of symbiotic insects. To further determine the role of rip-thanatin, we checked antimicrobial activity in vitro. Rip-thanatin showed high antimicrobial activity and had the same structural characteristics as other reported thanatins. To find the novel function of rip-thanatin, rip-thanatin was silenced by RNA interference, and the population of gut symbionts was measured. When rip-thanatin was silenced, the symbionts' titer was increased upon bacterial infection. These results suggest that rip-thanatin functions not only as an antimicrobial peptide but also in controlling the symbionts' titer in the host midgut.

Regulation of intestinal health by branched-chain amino acids

Besides its primary role in the digestion and absorption of nutrients, the intestine also interacts with a complex external milieu, and is the first defense line against noxious pathogens and antigens. Dysfunction of the intestinal barrier is associated with enhanced intestinal permeability and development of various gastrointestinal diseases. The branched-chain amino acids (BCAAs) are important nutrients, which are the essential substrates for protein biosynthesis. Recently, emerging evidence showed that BCAAs are involved in maintaining intestinal barrier function. It has been reported that dietary supplementation with BCAAs promotes intestinal development, enhances enterocyte proliferation, increases intestinal absorption of amino acids (AA) and glucose, and improves the immune defenses of piglets. The underlying mechanism of these effects is mediated by regulating expression of genes and proteins associate with various signaling pathways. In addition, BCAAs promote the production of beneficial bacteria in the intestine of mice. Compelling evidence supports the notion that BCAAs play important roles in both nutrition and intestinal health. Therefore, as functional amino acids with various physiological effects, BCAAs hold key roles in promoting intestinal development and health in animals and humans.

Ecology and Genomic Insights into Plant-Pathogenic and Plant-Nonpathogenic Endophytes

Plants are colonized on their surfaces and in the rhizosphere and phyllosphere by a multitude of different microorganisms and are inhabited internally by endophytes. Most endophytes act as commensals without any known effect on their plant host, but multiple bacteria and fungi establish a mutualistic relationship with plants, and some act as pathogens. The outcome of these plant-microbe interactions depends on biotic and abiotic environmental factors and on the genotype of the host and the interacting microorganism. In addition, endophytic microbiota and the manifold interactions between members, including pathogens, have a profound influence on the function of the system plant and the development of pathobiomes. In this review, we elaborate on the differences and similarities between nonpathogenic and pathogenic endophytes in terms of host plant response, colonization strategy, and genome content. We furthermore discuss environmental effects and biotic interactions within plant microbiota that influence pathogenesis and the pathobiome.

The gut-brain axis: is intestinal inflammation a silent driver of Parkinson's disease pathogenesis?

The state of the intestinal environment can have profound effects on the activity of the central nervous system through the physiological contributions of the microbiota, regulation of intestinal barrier function, and altered activity of peripheral neurons. The common language employed for much of the gut-brain communication is the modulation of immune activity. Chronic proinflammatory immune activity is increasingly being recognized as a fundamental element of neurodegenerative disorders, and in Parkinson's disease, inflammation in the intestine appears particularly relevant in pathogenesis. We review the evidence that intestinal dysfunction is present in Parkinson's disease and that it may reflect the earliest manifestations of Parkinson's disease pathology, and we link these findings to dysregulated immune activity. Based on this, we present a model for Parkinson's disease pathogenesis in which the disorder originates in the intestine and progresses with inflammation as its underlying mechanism. More in-depth investigations into the physiological mechanisms underlying peripheral pre-motor symptoms in Parkinson's disease are expected to lead to the development of novel diagnostic and therapeutic measures that can slow or limit progression of the disease to more advanced stages involving debilitating motor and cognitive symptoms.

[Microbiota-intestinal stem cells dialog: a key element for intestinal regeneration]

The most abundant and well-studied microbiota on the human body resides in the intestinal tract. Its impact extends the limits of the mucosal interface as it plays an essential role in systemic functions such as development of the immune system. At the level of the intestine, commensal microbes play important metabolic functions and promote the integrity of the mucosal barrier. Moreover, a large number of studies points to a role of the microbiota in intestinal regeneration both under homeostatic conditions and after epithelial damage. As intestinal regeneration is sustained by highly proliferative intestinal stem cells (ISCs), these observations raise the question of a direct impact of commensals on the activity of these cells. Key mediators of the dialog between microbes and the epithelium are the immune cells residing in the gut. Consistently, both innate lymphoid cells and macrophages activated by microbial stimuli have been shown to promote ISCs proliferation by secreting cytokines. More direct routes of communication have been described recently, either through the binding of bacterial ligands to Pattern Recognition Receptors expressed in ISCs, or through the sensing by ISCs of bacterial metabolites. In this review, we explore this stem cell-microbiota dialog and its impact on gut homeostasis.

Microbiota and pathogen 'pas de deux': setting up and breaking down barriers to intestinal infection

The gut microbiota plays essential roles in human health and disease. In this review, we focus on the role of the intestinal microbiota in promoting resistance to infection by bacterial pathogens as well as how pathogens overcome this barrier. We discuss how the resident microbiota restricts growth and colonization of invading pathogens by limiting availability of nutrients and through generation of a hostile environment. Additionally, we examine how microbiota-derived signaling molecules interfere with bacterial virulence. In turn, we discuss how pathogens exploit non-competitive metabolites to replicate in vivo as well as to precisely control virulence and cause disease. This bacterial two step of creating and overcoming challenges important in preventing and establishing infection highlights the complexities of elucidating interactions between the commensal bacteria and pathogens. Better understanding of microbiota-pathogen interplay will have significant implications for developing novel therapeutics to treat infectious diseases.

TGF-β Signaling in Dendritic Cells Governs Colonic Homeostasis by Controlling Epithelial Differentiation and the Luminal Microbiota

Dendritic cells (DCs) mediate host immune responses to gut microbes and play critical roles in inflammatory bowel disease. In this study, we examined the role of TGF-β signaling in DCs in colonic homeostasis. CD11c-cre Tgfbr2fl/fl mice developed spontaneous colitis, and CD11c-cre Tgfbr2fl/+ mice exhibited susceptibility to dextran sulfate sodium–induced colitis. Colitis in these mice was characterized by goblet cell depletion and dysbiosis caused by Enterobacteriaceae enrichment. Wild-type mice gavaged with Enterobacteriaceae from CD11c-cre Tgfbr2fl/fl mice feces showed severe colitis after dextran sulfate sodium treatment, whereas those treated with Notch inhibitor exhibited attenuated colonic injury with increased goblet cell numbers, thickened mucus layer, and fewer fecal Enterobacteriaceae. Wild-type mice transplanted with CD11c-cre Tgfbr2fl/fl bone marrow developed colitis showing increased Jagged1 and Jagged2 in DCs, increased Hes1 levels in epithelium, and goblet cell depletion. These findings suggest that TGF-β signaling in DCs regulates intestinal homeostasis by modulating epithelial cell differentiation and fecal microbiota.

Gut microbiota and related diseases

Gut microbiota is the normal flora in the human body, has a great effect on gut digestion and metabolism, and plays an important role in human health and diseases. Advances in research of gut microbiota has led to a better understanding of the relationship between gut microbiota and host immunity and diseases. This article aims to review the association of gut microbiota with the host immunity and related diseases, emphasizing the importance of gut microbiota.

Microbiome diversity in the sputum of patients with pulmonary tuberculosis

TB is a worldwide pandemic. India has the highest burden of TB, with WHO statistics for 2013 giving an estimated incidence figure of 2.1 million cases for India out of a global incidence of 9 million. Microbiota have been shown to be associated with many disease conditions; however, only few studies have been reported for microbiota associated with TB infection. For the first time, we characterized the composition of microbiota of TB patients of India, using high-throughput 16S rRNA gene sequencing and compared it with healthy controls. Phylum-level analysis showed that the relative abundance of Firmicutes and Actinobacteria was significantly higher in TB samples and Neisseria and Veillonella were two dominant genera after Streptococcus. In our study, significantly different core genera in TB and normal population were found as compared with the reported studies. Also, the presence of diverse opportunistic pathogenic microbiota in TB patients increases the complexity and diversity of sputum microbiota. Characterization of the sputum microbiome is likely to provide important pathogenic insights into pulmonary tuberculosis.

Macrophage polarization in response to oral commensals and pathogens

Macrophages have been identified in the periodontium. Data have phenotypically described these cells, demonstrated changes with progressing periodontal disease, and identified their ability to function in antigen-presentation critical for adaptive immune responses to individual oral bacterium. Recent evidence has emphasized an important role for the plasticity of macrophage phenotypes, not only in the resulting function of these cells in various tissues, but also clear differences in the stimulatory signals that result in M1 (classical activation, inflammatory) and M2 (alternative activation/deactivated, immunomodulatory) cells. This investigation hypothesized that the oral pathogens, Porphyromonas gingivalis and Aggregatibacter actinomycetemcomitans induce M1-type cells, while oral commensal bacteria primarily elicit macrophage functions consistent with an M2 phenotype. However, we observed that the M1 output from P. gingivalis challenge, showed exaggerated levels of pro-inflammatory cytokines, with a much lower production of chemokines related to T-cell recruitment. This contrasted with A. actinomycetemcomitans infection that increased both the pro-inflammatory cytokines and T-cell chemokines. Thus, it appears that P. gingivalis, as an oral pathogen, may have a unique capacity to alter the programming of the M1 macrophage resulting in a hyperinflammatory environment and minimizing the ability for T-cell immunomodulatory influx into the lesions.

Clinical implications of reduced susceptibility to fluoroquinolones in paediatric Shigella sonnei and Shigella flexneri infections

Objectives

We aimed to quantify the impact of fluoroquinolone resistance on the clinical outcome of paediatric shigellosis patients treated with fluoroquinolones in southern Vietnam. Such information is important to inform therapeutic management for infections caused by this increasingly drug-resistant pathogen, responsible for high morbidity and mortality in young children globally.

Methods

Clinical information and bacterial isolates were derived from a randomized controlled trial comparing gatifloxacin with ciprofloxacin for the treatment of paediatric shigellosis. Time–kill experiments were performed to evaluate the impact of MIC on the in vitro growth of Shigella and Cox regression modelling was used to compare clinical outcome between treatments and Shigella species.

Results

Shigella flexneri patients treated with gatifloxacin had significantly worse outcomes than those treated with ciprofloxacin. However, the MICs of fluoroquinolones were not significantly associated with poorer outcome. The presence of S83L and A87T mutations in the gyrA gene significantly increased MICs of fluoroquinolones. Finally, elevated MICs and the presence of the qnrS gene allowed Shigella to replicate efficiently in vitro in high concentrations of ciprofloxacin.

Conclusions

We found that below the CLSI breakpoint, there was no association between MIC and clinical outcome in paediatric shigellosis infections. However, S. flexneri patients had worse clinical outcomes when treated with gatifloxacin in this study regardless of MIC. Additionally, Shigella harbouring the qnrS gene are able to replicate efficiently in high concentrations of ciprofloxacin and we hypothesize that such strains possess a competitive advantage against fluoroquinolone-susceptible strains due to enhanced shedding and transmission.

Perioperative supplementation with bifidobacteria improves postoperative nutritional recovery, inflammatory response, and fecal microbiota in patients undergoing colorectal surgery: a prospective, randomized clinical trial

The use of probiotics has been widely documented to benefit human health, but their clinical value in surgical patients remains unclear. The present study investigated the effect of perioperative oral administration of probiotic bifidobacteria to patients undergoing colorectal surgery. Sixty patients undergoing colorectal resection were randomized to two groups prior to resection. One group (n=31) received a probiotic supplement, Bifidobacterium longum BB536, preoperatively for 7–14 days and postoperatively for 14 days, while the other group (n=29) received no intervention as a control. The occurrences of postoperative infectious complications were recorded. Blood and fecal samples were collected before and after surgery. No significant difference was found in the incidence of postoperative infectious complications and duration of hospital stay between the two groups. In comparison to the control group, the probiotic group tended to have higher postoperative levels of erythrocytes, hemoglobin, lymphocytes, total protein, and albumin and lower levels of high sensitive C-reactive proteins. Postoperatively, the proportions of fecal bacteria changed significantly; Actinobacteria increased in the probiotic group, Bacteroidetes and Proteobacteria increased in the control group, and Firmicutes decreased in both groups. Significant correlations were found between the proportions of fecal bacteria and blood parameters; Actinobacteria correlated negatively with blood inflammatory parameters, while Bacteroidetes and Proteobacteria correlated positively with blood inflammatory parameters. In the subgroup of patients who received preoperative chemoradiotherapy treatment, the duration of hospital stay was significantly shortened upon probiotic intervention. These results suggest that perioperative oral administration of bifidobacteria may contribute to a balanced intestinal microbiota and attenuated postoperative inflammatory responses, which may subsequently promote a healthy recovery after colorectal resection.

Localization-triggered bacterial pathogenesis

Bacterial infections are becoming an increasing problem worldwide and there is a need for a deeper understanding of how bacteria turn pathogenic. Here, we suggest that one answer may be found by taking into account the localization of the bacteria, both at an anatomical level and at a microenvironment level. Both commensals and traditional pathogens alter their interaction with the human host depending on the local surroundings--turning either more or less virulent. These localization effects could derive from the characteristics of different anatomical sites but also from local differences within a microenvironment. In order to understand the adaptive functions of bacterial virulence factors, we need to study the bacteria in the environments where they have evolved.

Differential Gene Expression Profiles Reflecting Macrophage Polarization in Aging and Periodontitis Gingival Tissues

Recent evidence has determined a phenotypic and functional heterogeneity for macrophage populations. This plasticity of macrophage function has been related to specific properties of subsets (M1 and M2) of these cells in inflammation, adaptive immune responses and resolution of tissue destructive processes. This investigation hypothesized that targeted alterations in the distribution of macrophage phenotypes in aged individuals, and with periodontitis would be skewed towards M1 inflammatory macrophages in gingival tissues. The study used a non-human primate model to evaluate gene expression profiles as footprints of macrophage variation in healthy and periodontitis gingival tissues from animals 3-23 years of age and in periodontitis tissues in adult and aged animals. Significant increases in multiple genes reflecting overall increases in macrophage activities were observed in healthy aged tissues, and were significantly increased in periodontitis tissues from both adults and aged animals. Generally, gene expression patterns for M2 macrophages were similar in healthy young, adolescent and adult tissues. However, modest increases were noted in healthy aged tissues, similar to those seen in periodontitis tissues from both age groups. M1 macrophage gene transcription patterns increased significantly over the age range in healthy tissues, with multiple genes (e.g. CCL13, CCL19, CCR7 and TLR4) significantly increased in aged animals. Additionally, gene expression patterns for M1 macrophages were significantly increased in adult health versus periodontitis and aged healthy versus periodontitis. The findings supported a significant increase in macrophages with aging and in periodontitis. The primary increases in both healthy aged tissues and, particularly periodontitis tissues appeared in the M1 phenotype.

Intestinal CD169(+) macrophages initiate mucosal inflammation by secreting CCL8 that recruits inflammatory monocytes

Lamina propria (LP) macrophages are constantly exposed to commensal bacteria, and are refractory to those antigens in an interleukin (IL)-10-dependent fashion. However, the mechanisms that discriminate hazardous invasion by bacteria from peaceful co-existence with them remain elusive. Here we show that CD169⁺ macrophages reside not at the villus tip, but at the bottom-end of the LP microenvironment. Following mucosal injury, the CD169⁺ macrophages recruit inflammatory monocytes by secreting CCL8. Selective depletion of CD169⁺ macrophages or administration of neutralizing anti-CCL8 antibody ameliorates the symptoms of experimentally induced colitis in mice. Collectively, we identify an LP-resident macrophage subset that links mucosal damage and inflammatory monocyte recruitment. Our results suggest that CD169⁺ macrophage-derived CCL8 serves as an emergency alert for the collapse of barrier defence, and is a promising target for the suppression of mucosal injury.

Macrophages and dendritic cells residing in the lamina propria are involved in controlling mucosal immune balance. Here, the authors identify CD169⁺ macrophages as contributors to the inflammation of DSS colitis through their role in mediating the recruitment of monocytes by secreting the cytokine CCL8.