To be or not to be a pathogen: that is the mucosally relevant question

Interaction between Intestinal Parasites and the Gut Microbiota: Implications for the Intestinal Immune Response and Host Defence

Intestinal parasites, including helminths and protozoa, account for a significant portion of the global health burden. The gastrointestinal (GI) tract not only serves as the stage for these parasitic infections but also as the residence for millions of microbes. As the intricacies of the GI microbial milieu continue to unfold, it is becoming increasingly apparent that the interactions between host, parasite, and resident microbes help dictate parasite survival and, ultimately, disease outcomes. Across both clinical and experimental models, intestinal parasites have been shown to impact microbial composition and diversity. Reciprocally, microbes can directly influence parasitic survival, colonization and expulsion. The gut microbiota can also indirectly impact parasites through the influence and manipulation of the host. Studying this host-parasite-microbiota axis may help bring about novel therapeutic strategies for intestinal parasitic infection as well as conditions such as inflammatory bowel disease (IBD). In this review, we explore the relationship between intestinal parasites, with a particular focus on common protozoa and helminths, and the gut microbiota, and how these interactions can influence the host defence and intestinal immune response. We will also explore the impact of this tripartite relationship in a clinical setting and its broader implications for human health.

Uterine microbial communities and their potential role in the regulation of epithelium cell cycle and apoptosis in aged hens

BACKGROUND

Alterations of the uterine microbiome are closely associated with various intrauterine diseases and physiological conditions, which are well-established in mammals. However, as representative oviparous animals, the research on the uterine microbial ecosystem and its functions with physiological homeostasis is limited in chickens. Additionally, continuous egg-laying disrupts the oviducal immune defenses of aged hens, susceptible to pathogen invasion, causing poor egg quality and food-borne infections in humans. Here, we investigated aging-related changes in the oviduct microbial colonization and transmission from the gut to eggs and their roles in a hen model.

RESULTS

The results of 16S rDNA sequencing showed significant differences in the oviduct microbial composition between young (38 weeks) and aged (77 weeks) laying hens. SourceTracker analysis further revealed differences in the effects of microbial transmission on the oviducal microbiota between young and aged hens. Enhanced barrier defense with cell apoptosis suppression and cell cycle arrest of the uterus were observed in aged hens reducing microbial transmission from the lower to upper reproductive tract. In addition, a total of 361 significantly differential metabolites were identified using metabolomics in the aged uterine microbiota, especially in products of amino acid metabolism and biosynthesis of various secondary metabolites, which might have essential effects on cell apoptosis by regulating immune responses and cell cycle. Notably, antibiotics disrupted uterine microbiota by dietary intervention and direct perfusion did not retard aging-related physiological changes but further aggravated aging processes by disrupting the cell cycle and apoptosis.

CONCLUSIONS

The microbiota continuum along the reproductive tract in aged birds differs from that in young birds, especially with a significant shift in the uterus. The aged uterine microbiota probably contributes to the regulation of cell cycle and apoptosis by microbial metabolites primarily involved in amino acid metabolism and biosynthesis of various secondary metabolites. These findings provide new insights into the roles of the reproductive tract microbiota in regulating the cell programming of the aged host, contributing to the exploration of the microbiome as a target for diagnosing aging health status and therapy for gynecological diseases in women. Video Abstract.

Food System Transformation and Gut Microbiota Transition: Evidence on Advancing Obesity, Cardiovascular Diseases, and Cancers-A Narrative Review

Food, a vital component of our daily life, is fundamental to our health and well-being, and the knowledge and practices relating to food have been passed down from countless generations of ancestors. Systems may be used to describe this extremely extensive and varied body of agricultural and gastronomic knowledge that has been gathered via evolutionary processes. The gut microbiota also underwent changes as the food system did, and these alterations had a variety of effects on human health. In recent decades, the gut microbiome has gained attention due to its health benefits as well as its pathological effects on human health. Many studies have shown that a person's gut microbiota partially determines the nutritional value of food and that diet, in turn, shapes both the microbiota and the microbiome. The current narrative review aims to explain how changes in the food system over time affect the makeup and evolution of the gut microbiota, advancing obesity, cardiovascular disease (CVD), and cancer. After a brief discussion of the food system's variety and the gut microbiota's functions, we concentrate on the relationship between the evolution of food system transformation and gut microbiota system transition linked to the increase of non-communicable diseases (NCDs). Finally, we also describe sustainable food system transformation strategies to ensure healthy microbiota composition recovery and maintain the host gut barrier and immune functions to reverse advancing NCDs.

Pathogenesis of allergic diseases and implications for therapeutic interventions

Allergic diseases such as allergic rhinitis (AR), allergic asthma (AAS), atopic dermatitis (AD), food allergy (FA), and eczema are systemic diseases caused by an impaired immune system. Accompanied by high recurrence rates, the steadily rising incidence rates of these diseases are attracting increasing attention. The pathogenesis of allergic diseases is complex and involves many factors, including maternal-fetal environment, living environment, genetics, epigenetics, and the body's immune status. The pathogenesis of allergic diseases exhibits a marked heterogeneity, with phenotype and endotype defining visible features and associated molecular mechanisms, respectively. With the rapid development of immunology, molecular biology, and biotechnology, many new biological drugs have been designed for the treatment of allergic diseases, including anti-immunoglobulin E (IgE), anti-interleukin (IL)-5, and anti-thymic stromal lymphopoietin (TSLP)/IL-4, to control symptoms. For doctors and scientists, it is becoming more and more important to understand the influencing factors, pathogenesis, and treatment progress of allergic diseases. This review aimed to assess the epidemiology, pathogenesis, and therapeutic interventions of allergic diseases, including AR, AAS, AD, and FA. We hope to help doctors and scientists understand allergic diseases systematically.

The mechanosensor Piezo1 rings the alarm on epithelial intruders

Recognition of invasive pathogens by the epithelium that is constantly exposed to microbial products remains incompletely understood. In a recent study, Tadala et al. demonstrated that the entry process of intracellular bacteria is itself a mechanical signal that is detected by the stretch-activated channel Piezo1, which triggers innate immune signaling.

Infection-induced membrane ruffling initiates danger and immune signaling via the mechanosensor PIEZO1

Microorganisms are generally sensed by receptors recognizing microbial molecules, which evoke changes in cellular activities and gene expression. Bacterial pathogens induce secretion of the danger signal ATP as an early alert response of intestinal epithelial cells, initiating overt inflammation. However, what triggers ATP secretion during infection is unclear. Here we show that the inherently mechanosensitive plasma membrane channel PIEZO1 acts as a sensor for bacterial entry. PIEZO1 is mechanically activated by invasion-induced membrane ruffles upstream of Ca²⁺ influx and ATP secretion. Mimicking mechanical stimuli of pathogen uptake with sterile beads equally elicits ATP secretion. Chemical or genetic PIEZO1 inactivation inhibits mechanically induced ATP secretion. Moreover, chemical or mechanical PIEZO1 activation evokes gene expression in immune and barrier pathways. Thus, mechanosensation of invasion-induced plasma membrane distortion initiates immune signaling upon infection, independently of detection of microbial molecules. Hence, PIEZO1-dependent detection of infection is driven by physical signals instead of chemical ligands.

The Role of Early Life Microbiota Composition in the Development of Allergic Diseases

Allergic diseases are becoming a major healthcare issue in many developed nations, where living environment and lifestyle are most predominantly distinct. Such differences include urbanized, industrialized living environments, overused hygiene products, antibiotics, stationary lifestyle, and fast-food-based diets, which tend to reduce microbial diversity and lead to impaired immune protection, which further increase the development of allergic diseases. At the same time, studies have also shown that modulating a microbiocidal community can ameliorate allergic symptoms. Therefore, in this paper, we aimed to review recent findings on the potential role of human microbiota in the gastrointestinal tract, surface of skin, and respiratory tract in the development of allergic diseases. Furthermore, we addressed a potential therapeutic or even preventive strategy for such allergic diseases by modulating human microbial composition.

On the Pathogenicity of the Oral Biofilm: A Critical Review from a Biological, Evolutionary, and Nutritional Point of View

Plaque control is one of the most recommended approaches in the prevention and therapy of caries and periodontal diseases. However, although most individuals in industrialized countries already perform daily oral hygiene, caries and periodontal diseases still are the most common diseases of mankind. This raises the question of whether plaque control is really a causative and effective approach to the prevention of these diseases. From an evolutionary, biological, and nutritional perspective, dental biofilms have to be considered a natural phenomenon, whereas several changes in human lifestyle factors during modern evolution are not “natural”. These lifestyle factors include the modern “Western diet” (rich in sugar and saturated fats and low in micronutrients), smoking, sedentary behavior, and continuous stress. This review hypothesizes that not plaque itself but rather these modern, unnatural lifestyle factors are the real causes of the high prevalence of caries and periodontal diseases besides several other non-communicable diseases. Accordingly, applying evolutionary and lifestyle medicine in dentistry would offer a causative approach against oral and common diseases, which would not be possible with oral hygiene approaches used on their own.

Eco-Evolutionary Dynamics of the Human-Gut Microbiota Symbiosis in a Changing Nutritional Environment

The operational harmony between living beings and their circumstances, their ever-changing environment, is a constitutive condition of their existence. Nutrition and symbiosis are two essential aspects of this harmony. Disruption of the symbiosis between host and gut microbiota, the so-called dysbiosis, as well as the inadequate diet from which it results, contribute to the etiology of immunometabolic disorders. Research into the development of these diseases is highly influenced by our understanding of the evolutionary roots of metabolic functioning, thereby considering that chronic non-communicable diseases arise from an evolutionary mismatch. However, the lens has been mostly directed toward energy availability and metabolism, but away from our closest environmental factor, the gut microbiota. Thus, this paper proposes a narrative thread that places symbiosis in an evolutionary perspective, expanding the traditional framework of humans’ adaptation to their food environment.

The Interplay Between Cervicovaginal Microbial Dysbiosis and Cervicovaginal Immunity

The cervicovaginal microbiota plays a key role in the health and reproductive outcomes of women. In reality epidemiological studies have demonstrated that there is an association between the structure of cervicovaginal microbiota and reproductive health, although key mechanistic questions regarding these effects remain unanswered and understanding the interplay between the immune system and the structure of the cervicovaginal microbiota. Here, we review existing literature relating to the potential mechanisms underlying the interaction between vaginal microbes and the immune system; we also describe the composition and function of the microbiome and explain the mechanisms underlying the interactions between these microbial communities and various aspects of the immune system. Finally, we also discuss the diseases that are caused by disorders of the reproductive tract and how the immune system is involved. Finally, based on the data presented in this review, the future perspectives in research directions and therapeutic opportunities are explored.

Oral and Intestinal Bacterial Substances Associated with Disease Activities in Patients with Rheumatoid Arthritis: A Cross-Sectional Clinical Study

Intestinal bacterial compositions of rheumatoid arthritis (RA) patients have been reported to be different from those of healthy people. Dysbiosis, imbalance of the microbiota, is widely known to cause gut barrier damage, resulting in an influx of bacteria and their substances into host bloodstreams in animal studies. However, few studies have investigated the effect of bacterial substances on the pathophysiology of RA. In this study, eighty-seven active RA patients who had inadequate responses to conventional synthetic disease-modifying antirheumatic drugs or severe comorbidities were analyzed for correlations between many factors such as disease activities, disease biomarkers, intestinal bacterial counts, fecal and serum lipopolysaccharide (LPS), LPS-binding protein (LBP), endotoxin neutralizing capacity (ENC), and serum antibacterial substance IgG and IgA antibody levels by multiple regression analysis with consideration for demographic factors such as age, sex, smoking, and methotrexate treatment. Serum LBP levels, fecal LPS levels, total bacteria counts, serum anti-LPS from Porphyromonas gingivalis (Pg-LPS) IgG antibody levels, and serum anti-Pg-LPS IgA antibody levels were selected for multiple regression analysis using Spearman’s correlation analysis. Serum LBP levels were correlated with disease biomarker levels, such as erythrocyte sedimentation rate ( $p<0.001$ ), C-reactive protein ( $p<0.001$ ), matrix metalloproteinase-3 ( $p<0.001$ ), and IL-6 ( $p=0.001$ ), and were inversely correlated with hemoglobin ( $p=0.005$ ). Anti-Pg-LPS IgG antibody levels were inversely correlated with activity indices such as patient global assessments using visual analogue scale (VAS) ( $p=0.002$ ) and painVAS ( $p<0.001$ ). Total bacteria counts were correlated with ENC ( $p<0.001$ ), and inversely correlated with serum LPS ( $p<0.001$ ) and anti-Pg-LPS IgA antibody levels ( $p<0.001$ ). These results suggest that substances from oral and gut microbiota may influence disease activity in RA patients.

The interaction of enteric bacterial effectors with the host engulfment pathway control innate immune responses

Host engulfment protein ELMO1 generates intestinal inflammation following internalization of enteric bacteria. In Shigella, bacterial effector IpgB1 interacts with ELMO1 and promotes bacterial invasion. IpgB1 belongs to the WxxxE effector family, a motif found in several effectors of enteric pathogens. Here, we have studied the role of WxxxE effectors, with emphasis on Salmonella SifA and whether it interacts with ELMO1 to regulate inflammation. In-silico-analysis of WxxxE effectors was performed using BLAST search and Clustal W program. The interaction of ELMO1 with SifA was assessed by GST pulldown assay and co-immunoprecipitation. ELMO1 knockout mice, and ELMO1-depleted murine macrophage J774 cell lines were challenged with WT and SifA mutant Salmonella. Bacterial effectors containing the WxxxE motif were transfected in WT and ELMO1-depleted J774 cells to assess the inflammatory cytokines. ELMO1 generates differential pro-inflammatory cytokines between pathogenic and nonpathogenic bacteria. WxxxE motif is present in pathogens and in the TIR domain of host proteins. The C-terminal part of ELMO1 interacts with SifA where WxxxE motif is important for interaction. ELMO1-SifA interaction affects bacterial colonization, dissemination, and inflammatory cytokines in vivo. Moreover, ELMO1-SifA interaction increases TNF-α and IL-6 production from the macrophage cell line and is associated with enhanced Rac1 activity. ELMO1 also interacts with WxxxE effectors IpgB1, IpgB2, and Map and induces inflammation after challenge with microbes or microbial ligands. ELMO1 generates a differential response through interaction with the WxxxE motif, which is absent in commensals. ELMO1-WxxxE interaction plays a role in bacterial pathogenesis and induction of inflammatory response.

Current Trends in IBD-Development of Mucosal-Based Biomarkers and a Novel Minimally Invasive Recoverable Sampling System

Despite recent developments in therapy for inflammatory bowel diseases (IBDs), there have been limited advances in diagnostic tools available to aid in disease management. A growing body of evidence suggests that there are important host-microbe interactions at the mucosal interface that modulate the inflammatory response in patients with IBD. Additionally, the importance of mucosal integrity and its disruption appears to be important in the pathophysiology and perpetuation of the disease. The ability to characterize this interface may provide valuable information for both disease monitoring and identification of new treatment targets. Endoscopy remains the primary tool for disease monitoring, and mucosal healing is the primary therapeutic target in IBD treatment. However, establishing mucosal healing requires repetitive endoscopic procedures, and endoscopy is limited by factors such as invasiveness, cost, and risk of adverse events. Moreover, the use of a bowel preparation for colonoscopies alters the mucus layer and thus perturbs evaluation of the host-microbe interaction. Stool sampling may also be inaccurate because it reflects the end state of metabolites and proteins, failing to take into account the degradation or alteration of substrates of interest by bacterial proteases and other enzymes during passage through the colon. A novel sampling capsule, called the Recoverable Sampling System (RSS), is being developed as a complementary tool to colonoscopy. The RSS is intended to be a platform for noninvasive autonomous sampling, preservation, handling, and storage of analytes of interest found in the gastrointestinal fluids. A proprietary preservative contained within the chambers of the capsule has been developed to stabilize DNA and proteins for ex vivo microbiome and metabolomics analyses. Surrogate markers such as SPP24 and GUCA2a have been identified to correlate with gut health, intestinal permeability, and inflammation and could be locally sampled by the RSS. The potential clinical utility of an RSS device is broad and would likely be able to guide therapy by allowing for more frequent disease monitoring, aiding in disease characterization, and facilitating in the identification of novel therapeutic targets.

Induction of IL-12p40 and type 1 immunity by Toxoplasma gondii in the absence of the TLR-MyD88 signaling cascade

Toxoplasma gondii is an orally acquired pathogen that induces strong IFN-γ based immunity conferring protection but that can also be the cause of immunopathology. The response in mice is driven in part by well-characterized MyD88-dependent signaling pathways. Here we focus on induction of less well understood immune responses that do not involve this Toll-like receptor (TLR)/IL-1 family receptor adaptor molecule, in particular as they occur in the intestinal mucosa. Using eYFP-IL-12p40 reporter mice on an MyD88^-/- background, we identified dendritic cells, macrophages, and neutrophils as cellular sources of MyD88-independent IL-12 after peroral T. gondii infection. Infection-induced IL-12 was lower in the absence of MyD88, but was still clearly above noninfected levels. Overall, this carried through to the IFN-γ response, which while generally decreased was still remarkably robust in the absence of MyD88. In the latter mice, IL-12 was strictly required to induce type I immunity. Type 1 and type 3 innate lymphoid cells (ILC), CD4⁺ T cells, and CD8⁺ T cells each contributed to the IFN-γ pool. We report that ILC3 were expanded in infected MyD88^-/- mice relative to their MyD88^+/+ counterparts, suggesting a compensatory response triggered by loss of MyD88. Furthermore, bacterial flagellin and Toxoplasma specific CD4⁺ T cell populations in the lamina propria expanded in response to infection in both WT and KO mice. Finally, we show that My88-independent IL-12 and T cell mediated IFN-γ production require the presence of the intestinal microbiota. Our results identify MyD88-independent intestinal immune pathways induced by T. gondii including myeloid cell derived IL-12 production, downstream type I immunity and IFN-γ production by ILC1, ILC3, and T lymphocytes. Collectively, our data reveal an underlying network of immune responses that do not involve signaling through MyD88.

Toxoplasma gondii is an apicomplexan parasite estimated to infect 30–50% of humans worldwide. The parasite normally establishes latency in brain and muscle tissue marked by persistent asymptomatic infection. T. gondii masterfully strikes a balance between eliciting strong, anti-parasite immunity while also persisting in the host. Although the murine host recognizes Toxoplasma profilin via MyD88 and Toll-like receptors 11/12, humans lack these receptors and MyD88 deficient patients retain resistance to T. gondii infection. Given these observations, it is important to identify MyD88 independent pathways of immunity. Using an oral infection mouse model, we identified cellular sources of IL-12 and IFN-γ, two cytokines that are essential for host resistance to this microbial pathogen. We determined how these responses are impacted by the presence and absence of MyD88 and the intestinal microbiota. Our data demonstrate that T. gondii triggers MyD88-independent innate and adaptive immunity in the intestinal mucosa that requires the presence of intestinal microbes. These pathways may be conserved among species and understanding how they work in rodents will likely help determine how humans recognize and respond to T. gondii infection.

Recent chemical syntheses of bacteria related oligosaccharides using modern expeditious approaches

Apart from some essential and crucial roles in life processes carbohydrates also are involved in a few detrimental courses of action related to human health, like infections by pathogenic microbes, cancer metastasis, transplanted tissue rejection, etc. Regarding management of pathogenesis by microbes, keeping in mind of multi drug-resistant bacteria and epidemic or endemic incidents, preventive measure by vaccination is the best pathway as also recommended by the WHO; by vaccination, eradication of bacterial diseases is also possible. Although some valid vaccines based on attenuated bacterial cells or isolated pure polysaccharide-antigens or the corresponding conjugates thereof are available in the market for prevention of several bacterial diseases, but these are not devoid of some disadvantages also. In order to develop improved conjugate T-cell dependent vaccines oligosaccharides related to bacterial antigens are synthesized and converted to the corresponding carrier protein conjugates. Marketed Cuban Quimi-Hib is such a vaccine being used since 2004 to resist Haemophilus influenza b infections. During nearly the past two decades research is going on worldwide for improved synthesis of bacteria related oligosaccharides or polysaccharides towards development of such semisynthetic or synthetic glycoconjugate vaccines. The present dissertation is an endeavour to encompass the recent syntheses of several pathogenic bacterial oligosaccharides or polysaccharides, made during the past ten-eleven years with special reference to modern expeditious syntheses.

Fructooligosaccharides improve growth performance and intestinal epithelium function in weaned pigs exposed to enterotoxigenic Escherichia coli

To explore the protective effect of Fructooligosaccharides (FOS) against Enterotoxigenic Escherichia coli (ETEC)-induced inflammation and intestinal injury, twenty-four weaned pigs were randomly assigned into three groups: (1) non-challenge (CON, fed with basal diet), (2) ETEC-challenge (ECON, fed with basal diet), and (3) ETEC challenge + FOS treatment (EFOS, fed with basal diet plus 2.5 g kg-1 FOS). On day 19, the CON group was orally infused with sterilized culture while pigs in the ECON group and EFOS group were orally infused with ETEC (2.5 × 1011 colony-forming units). After 3 days, pigs were slaughtered for sample collection. We showed that ETEC challenge significantly reduced average daily gain (ADG); however, FOS improved the ADG (P < 0.05), apparent digestibility of crude protein (CP), gross energy (GE), and ash and reduced the diarrhea incidence (P < 0.05). FOS reduced plasma concentrations of IL-1β and TNF-α and down-regulated (P < 0.05) the mRNA expression of IL-6 and TNF-α in the jejunum and ileum as well as IL-1β and TNF-α in the duodenum. The concentrations of plasma immunoglobulin A (IgA), immunoglobulin M (IgM) and secreted IgA (SIgA) in the jejunum (P < 0.05) were elevated. Interestingly, FOS elevated the villus height in the duodenum, and elevated the ratio of villus height to crypt depth in the duodenum and ileum in the EFOS group pigs (P < 0.05). Moreover, FOS increased lactase activity in the duodenum and ileum (P < 0.05). The activities of sucrase and alkaline phosphatase (AKP) were higher in the EFOS group than in the ECON group (P < 0.05). Importantly, FOS up-regulated the expressions of critical genes in intestinal epithelium function such as zonula occludens-1 (ZO-1), L-type amino acid transporter-1 (LAT1), and cationic amino acid transporter-1 (CAT1) in the duodenum and the expressions of ZO-1 and glucose transporter-2 (GLUT2) in the jejunum (P < 0.05). FOS also up-regulated the expressions of occludin, fatty acid transporter-4 (FATP4), sodium glucose transport protein 1 (SGLT1), and GLUT2 in the ileum (P < 0.05). FOS significantly increased the concentrations of acetic acid, propionic acid and butyric acid in the cecal digesta. Additionally, FOS reduced the populations of Escherichia coli, but elevated the populations of Bacillus and Bifidobacterium in the caecal digesta (P < 0.05). These results suggested that FOS could improve the growth performance and intestinal health in weaned pigs upon ETEC challenge, which was associated with suppressed inflammatory responses and improved intestinal epithelium functions and microbiota.

Discovery of Semi- and Fully-Synthetic Carbohydrate Vaccines Against Bacterial Infections Using a Medicinal Chemistry Approach

The glycocalyx, a thick layer of carbohydrates, surrounds the cell wall of most bacterial and parasitic pathogens. Recognition of these unique glycans by the human immune system results in destruction of the invaders. To elicit a protective immune response, polysaccharides either isolated from the bacterial cell surface or conjugated with a carrier protein, for T-cell help, are administered. Conjugate vaccines based on isolated carbohydrates currently protect millions of people against Streptococcus pneumoniae, Haemophilus influenzae type b, and Neisseria meningitides infections. Active pharmaceutical ingredients (APIs) are increasingly discovered by medicinal chemistry and synthetic in origin, rather than isolated from natural sources. Converting vaccines from biologicals to pharmaceuticals requires a fundamental understanding of how the human immune system recognizes carbohydrates and could now be realized. To illustrate the chemistry-based approach to vaccine discovery, I summarize efforts focusing on synthetic glycan-based medicinal chemistry to understand the mammalian antiglycan immune response and define glycan epitopes for novel synthetic glycoconjugate vaccines against Streptococcus pneumoniae, Clostridium difficile, Klebsiella pneumoniae, and other bacteria. The chemical tools described here help us gain fundamental insights into how the human system recognizes carbohydrates and drive the discovery of carbohydrate vaccines.

Subclinical infection can be an initiator of inflammaging leading to degenerative disk disease: evidence from host-defense response mechanisms

PURPOSE

There is considerable controversy on the role of genetics, mechanical and environmental factors, and, recently, on subclinical infection in triggering inflammaging leading to disk degeneration. The present study investigated sequential molecular events in the host, analyzing proteome level changes that will reveal triggering factors of inflammaging and degeneration.

METHODS

Ten MRI normal disks (ND) from braindead organ donors and 17 degenerated disks (DD) from surgery were subjected to in-gel-based label-free ESI-LC-MS/MS analysis. Bacterial-responsive host-defense response proteins/pathways leading to Inflammaging were identified and compared between ND and DD.

RESULTS

Out of the 263 well-established host-defense response proteins (HDRPs), 243 proteins were identified, and 64 abundantly expressed HDRPs were analyzed further. Among the 21 HDRPs common to both ND and DD, complement factor 3 (C3) and heparan sulfate proteoglycan 2 (HSPG2) were significantly upregulated, and lysozyme (LYZ), superoxide dismutase 3 (SOD3), phospholipase-A2 (PLA2G2A), and tissue inhibitor of metalloproteinases 3 (TIMP-3) were downregulated in DD. Forty-two specific HDRPs mainly, complement proteins, apolipoproteins, and antimicrobial proteins involved in the complement cascade, neutrophil degranulation, and oxidative-stress regulation pathways representing an ongoing host response to subclinical infection and uncontrolled inflammation were identified in DD. Protein-Protein interaction analysis revealed cross talk between most of the expressed HDRPs, adding evidence to bacterial presence and stimulation of these defense pathways.

CONCLUSIONS

The predominance of HDRPs involved in complement cascades, neutrophil degranulation, and oxidative-stress regulation indicated an ongoing infection mediated inflammatory process in DD. Our study has documented increasing evidence for bacteria's role in triggering the innate immune system leading to chronic inflammation and degenerative disk disease.

Interaction between IgA and gut microbiota and its role in controlling metabolic syndrome

Immunoglobulin A (IgA) is the most abundant immunoglobulin isotype secreted into the mucosal tissues, mainly intestinal mucus. Humans can produce several grams of IgA every day, accounting for three quarters of the body's total immunoglobulin content. IgA, together with mucus and antimicrobial peptides, forms the first line of defence for intestinal epithelial cells, protecting them from a significant number of intestinal antigens. IgA also plays a principal role in controlling the gut microbiota (GM), and disruption in IgA can result in dysbiosis, such as the enrichment of Proteobacteria, which are generally bound by IgA. Proteobacteria overexpansion is also usually seen in obesity and colitis. Consistent with this, IgA dysfunction frequently results in metabolic syndrome (MetS), including conditions such as obesity, adiposity, insulin resistance, and inflammation. In contrast, enhanced IgA function can improve, and even prevent, MetS. Interactions among IgA, GM, and metabolism provide a promising avenue to combat MetS.

From Initiators to Effectors: Roadmap Through the Intestine During Encounter of Toxoplasma gondii With the Mucosal Immune System

The gastrointestinal tract is a major portal of entry for many pathogens, including the protozoan parasite Toxoplasma gondii. Billions of people worldwide have acquired T. gondii at some point in their life, and for the vast majority this has led to latent infection in the central nervous system. The first line of host defense against Toxoplasma is located within the intestinal mucosa. Appropriate coordination of responses by the intestinal epithelium, intraepithelial lymphocytes, and lamina propria cells results in an inflammatory response that controls acute infection. Under some conditions, infection elicits bacterial dysbiosis and immune-mediated tissue damage in the intestine. Here, we discuss the complex interactions between the microbiota, the epithelium, as well as innate and adaptive immune cells in the intestinal mucosa that induce protective immunity, and that sometimes switch to inflammatory pathology as T. gondii encounters tissues of the gut.

Not by structures alone: Can the immune system recognize microbial functions?

A central question for immunology is: what does the immune system recognize and according to which principles does this kind of recognition work? Immunology has been dominated by the idea of recognizing molecular structures and triggering an appropriate immune response when facing non-self or danger. Recently, characterizations in terms of function have turned out to be more conserved and explanatory in microbiota research than taxonomic composition for understanding microbiota-host interactions. Starting from a conceptual analysis of the notions of structure and function, I raise the title question whether it is possible for the immune system to recognize microbial functions. I argue that this is indeed the case, making the claim that some function-associated molecular patterns are not indicative of the presence of certain taxa (''who is there'') but of biochemical activities and effects (''what is going on''). In addition, I discuss case studies which show that there are immunological sensors that can directly detect microbial activities, irrespective of their specific structural manifestation. At the same time, the discussed account puts the causal role notions of function on a more realist and objective basis.

Thanatomicrobiome and epinecrotic community signatures for estimation of post-mortem time interval in human cadaver

Estimation of post-mortem time interval (PMI) is a key parameter in the forensic investigation which poses a huge challenge to the medico-legal experts. The succession of microbes within different parts of the human body after death has shown huge potential in the determination of PMI. Human body harbors trillions of microorganisms as commensals. With the death of an individual when biological functions are stopped, these microorganisms behave contrarily along with the invasion of degrading microbes from the environment. Human cadaver becomes a rich source of nutrients due to autolysis of cells, which attracts various invading microorganisms as well as macroorganisms. At different stages of degradation, the succession of microorganisms differs significantly which can be explored for accurate PMI estimation. With the advent of microbial genomics technique and reduction in the cost of DNA sequencing, thanatomicrobiome and epinecrotic community analysis have gained huge attention in PMI estimation. The article summarizes different sources of microorganisms in a human cadaver, their succession pattern, and analytical techniques for application in the field of microbial forensics. KEY POINTS: • Thanatomicrobiome and epinecrotic microbiome develop in postmortem human body. • Lack of metabolic, immune, neuroendocrine systems facilitate microbial succession. • Analysis of postmortem microbial communities predicts accurate PMI.

Bacterial vaginosis in pregnancy - a storm in the cup of tea

Human vaginal microbiota is dominated by Lactobacillus spp both in the non-pregnant and pregnant state. Bacterial vaginosis (BV) is an imbalance of vaginal microbiota caused by a reduction in the normal lactobacillary bacteria, and a heavy over-growth of mixed anaerobic bacteria. Various clinical (Amsel's Criteria), laboratory (Nugent's score) and molecular diagnostic method (quantitative PCR) are used for diagnosis. BV in pregnancy is associated with increased risk of preterm birth, low birth weight, chorioamnionitis and postpartum endometritis, apart from bothersome vaginal discharge. Antibiotic treatment with metronidazole or clindamycin are effective in eradicating bacterial vaginosis and safe to use in pregnancy. Treatment of bacterial vaginosis has not been shown to improve obstetric outcomes in women at low risk of preterm birth, but may reduce the risk of preterm birth and low birth weight in women at increased risk of preterm birth. Routine screening and treatment is not recommended in low risk women. Test for cure should be performed after treatment. Further research is required on other treatment modalities such as probiotic therapy and microbiota transplantation.

The lung microbiota: role in maintaining pulmonary immune homeostasis and its implications in cancer development and therapy

Like other body districts, lungs present a complex bacteria community. An emerging function of lung microbiota is to promote and maintain a state of immune tolerance, to prevent uncontrolled and not desirable inflammatory response caused by inhalation of harmless environmental stimuli. This effect is mediated by a continuous dialog between commensal bacteria and immune cells resident in lungs, which express a repertoire of sensors able to detect microorganisms. The same receptors are also involved in the recognition of pathogens and in mounting a proper immune response. Due to its important role in preserving lung homeostasis, the lung microbiota can be also considered a mirror of lung health status. Indeed, several studies indicate that lung bacterial composition drastically changes during the occurrence of pulmonary pathologies, such as lung cancer, and the available data suggest that the modifications of lung microbiota can be part of the etiology of tumors in lungs and can influence their progression and response to therapy. These results provide the scientific rationale to analyze lung microbiota composition as biomarker for lung cancer and to consider lung microbiota a new potential target for therapeutic intervention to reprogram the antitumor immune microenvironment. In the present review, we discussed about the role of lung microbiota in lung physiology and summarized the most relevant data about the relationship between lung microbiota and cancer.

Effects of GABA Supplementation on Intestinal SIgA Secretion and Gut Microbiota in the Healthy and ETEC-Infected Weanling Piglets

Pathogenic enterotoxigenic Escherichia coli (ETEC) has been considered a major cause of diarrhea which is a serious public health problem in humans and animals. This study was aimed at examining the effect of γ-aminobutyric acid (GABA) supplementation on intestinal secretory immunoglobulin A (SIgA) secretion and gut microbiota profile in healthy and ETEC-infected weaning piglets. A total of thirty-seven weaning piglets were randomly distributed into two groups fed with the basal diet or supplemented with 40 mg·kg-1 of GABA for three weeks, and some piglets were infected with ETEC at the last week. According to whether ETEC was inoculated or not, the experiment was divided into two stages (referred as CON1 and CON2 and GABA1 and GABA2). The growth performance, organ indices, amino acid levels, and biochemical parameters of serum, intestinal SIgA concentration, gut microbiota composition, and intestinal metabolites were analyzed at the end of each stage. We found that, in both the normal and ETEC-infected piglets, jejunal SIgA secretion and expression of some cytokines, such as IL-4, IL-13, and IL-17, were increased by GABA supplementation. Meanwhile, we observed that some low-abundance microbes, like Enterococcus and Bacteroidetes, were markedly increased in GABA-supplemented groups. KEGG enrichment analysis revealed that the nitrogen metabolism, sphingolipid signaling pathway, sphingolipid metabolism, and microbial metabolism in diverse environments were enriched in the GABA1 group. Further analysis revealed that alterations in microbial metabolism were closely correlated to changes in the abundances of Enterococcus and Bacteroidetes. In conclusion, GABA supplementation can enhance intestinal mucosal immunity by promoting jejunal SIgA secretion, which might be related with the T-cell-dependent pathway and altered gut microbiota structure and metabolism.

Failure of serological testing for antigens A and C of Streptococcus equi subspecies equi to identify guttural pouch carriers

BACKGROUND

Serology is commonly used as a means of identifying horses that might be chronic and silent carriers of S. equi but its sensitivity is rarely examined.

OBJECTIVES

The study was designed to investigate the sensitivity of serological testing for antibodies against S. equi antigens A and C to detect guttural pouch carriers of S. equi.

STUDY DESIGN

Retrospective clinical study.

METHODS

As part of routine surveillance and quarantine procedures horses arriving at a welfare charity quarantine unit were subject to both microbiological sampling of guttural pouches and also serological testing for antibodies directed at S. equi antigens A and C. Laboratory results and endoscopic findings were examined to determine associations between serological results and guttural pouch carriage of S. equi.

RESULTS

Of 287 included horses, 9 (3.1%) were found to be guttural pouch carriers. There was no significant association between serological status and guttural pouch carriage of S. equi Only one of the nine carriers (11%) was seropositive using a cut-off of OD ≥ 0.5, and only three of nine (33%) using a cut-off of OD ≥ 0.3.

MAIN LIMITATIONS

Horses examined in this study were new arrivals at a welfare centre rather than from a general, well-managed, equid population. As a retrospective clinical study, the laboratory test results could not be repeated for further confirmation.

CONCLUSIONS

Caution is advised when relying on seronegativity to antigens A and C in order to discount the possibility of chronic carriage of S. equi in guttural pouches.

The Bacterial Microbiota of Gastrointestinal Cancers: Role in Cancer Pathogenesis and Therapeutic Perspectives

The microbiota has an essential role in the pathogenesis of many gastrointestinal diseases including cancer. This effect is mediated through different mechanisms such as damaging DNA, activation of oncogenic pathways, production of carcinogenic metabolites, stimulation of chronic inflammation, and inhibition of antitumor immunity. Recently, the concept of "pharmacomicrobiomics" has emerged as a new field concerned with exploring the interplay between drugs and microbes. Mounting evidence indicates that the microbiota and their metabolites have a major impact on the pharmacodynamics and therapeutic responses toward anticancer drugs including conventional chemotherapy and molecular-targeted therapeutics. In addition, microbiota appears as an attractive target for cancer prevention and treatment. In this review, we discuss the role of bacterial microbiota in the pathogenesis of different cancer types affecting the gastrointestinal tract system. We also scrutinize the evidence regarding the role of microbiota in anticancer drug responses. Further, we discuss the use of probiotics, fecal microbiota transplantation, and antibiotics, either alone or in combination with anticancer drugs for prevention and treatment of gastrointestinal tract cancers.

Microbiome Composition and Its Impact on the Development of Allergic Diseases

Allergic diseases, such as food allergy (FA), atopic dermatitis (AD), and asthma, are heterogeneous inflammatory immune-mediated disorders that currently constitute a public health issue in many developed countries worldwide. The significant increase in the prevalence of allergic diseases reported over the last few years has closely paralleled substantial environmental changes both on a macro and micro scale, which have led to reduced microbial exposure in early life and perturbation of the human microbiome composition. Increasing evidence shows that early life interactions between the human microbiome and the immune cells play a pivotal role in the development of the immune system. Therefore, the process of early colonization by a “healthy” microbiome is emerging as a key determinant of life-long health. In stark contrast, the perturbation of such a process, which results in changes in the host-microbiome biodiversity and metabolic activities, has been associated with greater susceptibility to immune-mediated disorders later in life, including allergic diseases. Here, we outline recent findings on the potential contribution of the microbiome in the gastrointestinal tract, skin, and airways to the development of FA, AD, and asthma. Furthermore, we address how the modulation of the microbiome composition in these different body districts could be a potential strategy for the prevention and treatment of allergic diseases.

The Interplay Between Reproductive Tract Microbiota and Immunological System in Human Reproduction

In the last decade, the microbiota, i.e., combined populations of microorganisms living inside and on the surface of the human body, has increasingly attracted attention of researchers in the medical field. Indeed, since the completion of the Human Microbiome Project, insight and interest in the role of microbiota in health and disease, also through study of its combined genomes, the microbiome, has been steadily expanding. One less explored field of microbiome research has been the female reproductive tract. Research mainly from the past decade suggests that microbial communities residing in the reproductive tract represent a large proportion of the female microbial network and appear to be involved in reproductive failure and pregnancy complications. Microbiome research is facing technological and methodological challenges, as detection techniques and analysis methods are far from being standardized. A further hurdle is understanding the complex host-microbiota interaction and the confounding effect of a multitude of constitutional and environmental factors. A key regulator of this interaction is the maternal immune system that, during the peri-conceptional stage and even more so during pregnancy, undergoes considerable modulation. This review aims to summarize the current literature on reproductive tract microbiota describing the composition of microbiota in different anatomical locations (vagina, cervix, endometrium, and placenta). We also discuss putative mechanisms of interaction between such microbial communities and various aspects of the immune system, with a focus on the characteristic immunological changes during normal pregnancy. Furthermore, we discuss how abnormal microbiota composition, “dysbiosis,” is linked to a spectrum of clinical disorders related to the female reproductive system and how the maternal immune system is involved. Finally, based on the data presented in this review, the future perspectives in diagnostic approaches, research directions and therapeutic opportunities are explored.

The Effects of Secretory IgA in the Mucosal Immune System

Immunoglobulin A (IgA) is the most abundant antibody isotype in the mucosal immune system. Structurally, IgA in the mucosal surface is a polymeric structure, while serum IgA is monomeric. Secretory IgA (sIgA) is one of the polymeric IgAs composed of dimeric IgA, J chain, and secretory component (SC). Most of sIgAs were generated by gut and have effects in situ. Besides the function of “immune exclusion,” a nonspecific immune role, recent studies found it also played an important role in the specific immunity and immunoregulation. Thanks to the critical role of sIgA during the mucosal immune system homeostasis between commensal microorganisms and pathogens; it has been an important field exploring the relationship between sIgA and commensal microorganisms.

Identification of Virulence-Associated Properties by Comparative Genome Analysis of Streptococcus pneumoniae, S. pseudopneumoniae, S. mitis, Three S. oralis Subspecies, and S. infantis

Streptococcus pneumoniae is one of the most important human pathogens but is closely related to Streptococcus mitis, with which humans live in harmony. The fact that the two species evolved from a common ancestor provides a unique basis for studies of both infection-associated properties and properties important for harmonious coexistence with the host. By detailed comparisons of genomes of the two species and other related streptococci, we identified 224 genes associated with virulence and 25 genes unique to the mutualistic species. The exclusive presence of the virulence factors in S. pneumoniae enhances their potential as vaccine components, as a direct impact on beneficial members of the commensal microbiota can be excluded. Successful adaptation of S. mitis and other commensal streptococci to a harmonious relationship with the host relied on genetic stability and properties facilitating life in biofilms.

From a common ancestor, Streptococcus pneumoniae and Streptococcus mitis evolved in parallel into one of the most important pathogens and a mutualistic colonizer of humans, respectively. This evolutionary scenario provides a unique basis for studies of both infection-associated properties and properties important for harmonious coexistence with the host. We performed detailed comparisons of 60 genomes of S. pneumoniae, S. mitis, Streptococcus pseudopneumoniae, the three Streptococcus oralis subspecies oralis, tigurinus, and dentisani, and Streptococcus infantis. Nonfunctional remnants of ancestral genes in both S. pneumoniae and in S. mitis support the evolutionary model and the concept that evolutionary changes on both sides were required to reach their present relationship to the host. Confirmed by screening of >7,500 genomes, we identified 224 genes associated with virulence. The striking difference to commensal streptococci was the diversity of regulatory mechanisms, including regulation of capsule production, a significantly larger arsenal of enzymes involved in carbohydrate hydrolysis, and proteins known to interfere with innate immune factors. The exclusive presence of the virulence factors in S. pneumoniae enhances their potential as vaccine components, as a direct impact on beneficial members of the commensal microbiota can be excluded. In addition to loss of these virulence-associated genes, adaptation of S. mitis to a mutualistic relationship with the host apparently required preservation or acquisition of 25 genes lost or absent from S. pneumoniae. Successful adaptation of S. mitis and other commensal streptococci to a harmonious relationship with the host relied on genetic stability and properties facilitating life in biofilms.

Disentangling bacterial invasiveness from lethality in an experimental host-pathogen system

Quantifying virulence remains a central problem in human health, pest control, disease ecology, and evolutionary biology. Bacterial virulence is typically quantified by the LT50 (i.e., the time taken to kill 50% of infected hosts); however, such an indicator cannot account for the full complexity of the infection process, such as distinguishing between the pathogen's ability to colonize versus kill the hosts. Indeed, the pathogen needs to breach the primary defenses in order to colonize, find a suitable environment to replicate, and finally express the virulence factors that cause disease. Here, we show that two virulence attributes, namely pathogen lethality and invasiveness, can be disentangled from the survival curves of a laboratory population of Caenorhabditis elegans nematodes exposed to three bacterial pathogens: Pseudomonas aeruginosa, Serratia marcescens, and Salmonella enterica We first show that the host population eventually experiences a constant mortality rate, which quantifies the lethality of the pathogen. We then show that the time necessary to reach this constant mortality rate regime depends on the pathogen growth rate and colonization rate, and thus determines the pathogen invasiveness. Our framework reveals that Serratia marcescens is particularly good at the initial colonization of the host, whereas Salmonella enterica is a poor colonizer yet just as lethal once established. Pseudomonas aeruginosa, on the other hand, is both a good colonizer and highly lethal after becoming established. The ability to quantitatively characterize the ability of different pathogens to perform each of these steps has implications for treatment and prevention of disease and for the evolution and ecology of pathogens.

Fimbriae reprogram host gene expression - Divergent effects of P and type 1 fimbriae

Pathogens rely on a complex virulence gene repertoire to successfully attack their hosts. We were therefore surprised to find that a single fimbrial gene reconstitution can return the virulence-attenuated commensal strain Escherichia coli 83972 to virulence, defined by a disease phenotype in human hosts. E. coli 83972pap stably reprogrammed host gene expression, by activating an acute pyelonephritis-associated, IRF7-dependent gene network. The PapG protein was internalized by human kidney cells and served as a transcriptional agonist of IRF-7, IFN-β and MYC, suggesting direct involvement of the fimbrial adhesin in this process. IRF-7 was further identified as a potent upstream regulator (-log (p-value) = 61), consistent with the effects in inoculated patients. In contrast, E. coli 83972fim transiently attenuated overall gene expression in human hosts, enhancing the effects of E. coli 83972. The inhibition of RNA processing and ribosomal assembly indicated a homeostatic rather than a pathogenic end-point. In parallel, the expression of specific ion channels and neuropeptide gene networks was transiently enhanced, in a FimH-dependent manner. The studies were performed to establish protective asymptomatic bacteriuria in human hosts and the reconstituted E. coli 83972 variants were developed to improve bacterial fitness for the human urinary tract. Unexpectedly, P fimbriae were able to drive a disease response, suggesting that like oncogene addiction in cancer, pathogens may be addicted to single super-virulence factors.

Urinary tract infections affect millions of individuals annually, and many patients suffer from recurring infections several times a year. Antibiotic resistance is increasing rapidly and new strategies are needed to treat even these common bacterial infections. One approach is to use the protective power of asymptomatic bacterial carriage, which has been shown to protect the host against symptomatic urinary tract infection. Instilling “nice” bacteria in the urinary bladder is therefore a promising alternative approach to antibiotic therapy. In an effort to increase the therapeutic use of asymptomatic bacteriuria, we reintroduced bacterial adhesion molecules into the therapeutic Escherichia coli strain 83972 and inoculated patients who are in need of alternative therapy. To our great surprise, the P fimbriated variant caused symptoms, despite lacking other virulence factors commonly thought to be necessary to cause disease. In contrast, type 1 fimbriae, did not provoke symptoms but enhanced the beneficial properties of the wild-type strain. This is explained by a divergent effect of these fimbrial types on host gene expression, where P fimbriae activate the IRF-7 transcription factor that regulates pathology in infected kidneys, suggesting that a single, potent virulence gene may be sufficient to create virulence in human hosts.

Host immunoglobulin G selectively identifies pathobionts in pediatric inflammatory bowel diseases

BACKGROUND

Inflammatory bowel diseases (IBD) are a group of complex and multifactorial disorders with unknown etiology. Chronic intestinal inflammation develops against resident intestinal bacteria in genetically susceptible hosts. We hypothesized that host intestinal immunoglobulin (Ig) G can be used to identify bacteria involved in IBD pathogenesis.

RESULTS

IgG-bound and -unbound microorganisms were collected from 32 pediatric terminal ileum aspirate washes during colonoscopy [non-IBD (n = 10), Crohn disease (n = 15), and ulcerative colitis (n = 7)], and composition was assessed using the Illumina MiSeq platform. In vitro analysis of invasive capacity was evaluated by fluorescence in situ hybridization and gentamicin invasion assay; immune activation was measured by qPCR. Despite considerable inter-individual variations, IgG binding favored specific and unique mucosa-associated species in pediatric IBD patients. Burkholderia cepacia, Flavonifractor plautii, and Rumminococcus sp. demonstrated increased IgG binding, while Pseudomonas ST29 demonstrated reduced IgG binding, in IBD. In vitro validation confirmed that B. cepacia, F. plautii, and Rumminococcus display invasive potential while Pseudomonas protogens did not.

CONCLUSION

Using IgG as a marker of pathobionts in larger patient cohorts to identify microbes and elucidate their role in IBD pathogenesis will potentially underpin new strategies to facilitate development of novel, targeted diagnostic, and therapeutic approaches. Interestingly, this method can be used beyond the scope of this manuscript to evaluate altered gut pathobionts in a number of diseases associated with altered microbiota including arthritis, obesity, diabetes mellitus, alcoholic liver disease, cirrhosis, metabolic syndrome, and carcinomas.

Diabetic gut microbiota dysbiosis as an inflammaging and immunosenescence condition that fosters progression of retinopathy and nephropathy

The increased prevalence of type 2 diabetes mellitus (T2DM) and life expectancy of diabetic patients fosters the worldwide prevalence of retinopathy and nephropathy, two major microvascular complications that have been difficult to treat with contemporary glucose-lowering medications. The gut microbiota (GM) has become a lively field research in the last years; there is a growing recognition that altered intestinal microbiota composition and function can directly impact the phenomenon of ageing and age-related disorders. In fact, human GM, envisaged as a potential source of novel therapeutics, strongly modulates host immunity and metabolism. It is now clear that gut dysbiosis and their products (e.g. p-cresyl sulfate, trimethylamine‑N‑oxide) dictate a secretory associated senescence phenotype and chronic low-grade inflammation, features shared in the physiological process of ageing ("inflammaging") as well as in T2DM ("metaflammation") and in its microvascular complications. This review provides an in-depth look on the crosstalk between GM, host immunity and metabolism. Further, it characterizes human GM signatures of elderly and T2DM patients. Finally, a comprehensive scrutiny of recent molecular findings (e.g. epigenetic changes) underlying causal relationships between GM dysbiosis and diabetic retinopathy/nephropathy complications is pinpointed, with the ultimate goal to unravel potential pathophysiological mechanisms that may be explored, in a near future, as personalized disease-modifying therapeutic approaches.

Microbial Changes and Host Response in F344 Rat Colon Depending on Sex and Age Following a High-Fat Diet

Gut microbiota, an important component that affects host health, change rapidly and directly in response to altered diet composition. Recently, the role of diet–microbiome interaction on the development of colon cancer has been the focus of interest. Colon cancer occurs more frequently in an aged population, and in males. However, the effect of dietary changes on the gut microbiome has been studied mainly in young males, even though it may vary with age and sex. The aim of this study was to investigate microbial changes and host response in the colons of male and female 6-week-old (young) and 2-year-old (old) Fisher-344 rats exposed to a high-fat diet (HFD). Our results showed that exposure to HFD for 8 weeks decreased the species richness of microbiota (Chao1) and increased Firmicutes/Bacteroidetes ratio only in aged rats, and not in young rats. Sex differences underlying the alteration by HFD in the gut microbiome were observed in the microbiome of aged rats. For instance, the abundance ratio of Akkermansia muciniphila and Desulfovibrio spp. increased in response to HFD in young rats and female aged rats, but not in male aged rats. Histological inflammation and cell proliferation of colon mucosa (indexed by Ki67) were significantly increased by HFD even in young rats; aged rats showed significantly higher cell proliferation in the HFD group than in the control. The HFD-induced decrease of species richness and the increase in specific species (Desulfovibrio spp. and Clostridium lavalense), which produce carcinogenic compounds such as H₂S and N-nitroso compounds, were significantly correlated with Ki67 index. In colon mucosa, the concentration of myeloperoxidase was increased by HFD only in males, and not in females. In conclusion, the results suggest a link between HFD-induced gut dysbiosis (particularly the low species richness and high abundance ratios of Desulfovibrio spp. and C. lavalense) and cell proliferation of colon mucosa (indicated by Ki67 IHC). In addition, sex differences influence the response of gut microbiome to HFD particularly in old age. Such sex differences in the gut microbiota might be related to sex differences in inflammation in the colon mucosa.

Immunomodulatory Effects of 17β-Estradiol on Epithelial Cells during Bacterial Infections

The innate immune system can function under hormonal control. 17β-Estradiol (E2) is an important sexual hormone for the reproductive cycle of mammals, and it has immunomodulatory effects on epithelial cells, which are the first line of defense against incoming bacteria. E2 regulates various pathophysiological processes, including the response to infection in epithelial cells, and its effects involve the regulation of innate immune signaling pathways, which are mediated through estrogen receptors (ERs). E2 modulates the expression of inflammatory and antimicrobial elements such as cytokines and antimicrobial peptides. The E2 effects on epithelial cells during bacterial infections are characterized by an increase in the production of antimicrobial peptides and by the diminution of the inflammatory response to abrogate proinflammatory cytokine induction by bacteria. Here, we review several novel molecular mechanisms through which E2 regulates the innate immune response of epithelial cells against bacterial infections.

Detection of Fusobacterium spp in colorectal tissue samples using reverse transcription polymerase chain reaction with minor groove binder probes: an exploratory research

An unhealthy microbiome is intimately correlated with several disease states, including colorectal cancer, wherein bacteria might be the key to neoplastic initiation and progression. Recent studies revealed an enrichment of Fusobacterium in colorectal tumor tissues relative to surrounding normal mucosa. Given the available evidence, we conducted an exploratory study quantifying the relative expression of Fusobacterium spp in 28 tissue samples from patients treated at Centro Hospitalar de São João belonging to 4 different groups: adenomas, paired normal tissue from patients with adenomas, carcinomas, and paired normal tissue from patients with colorectal carcinomas. To increase reverse transcription polymerase chain reaction quantification sensitivity, minor groove binders fluorescent probes were used, having in mind its implementation into routine clinical practice. Differences of Fusobacterium spp relative abundance between paired neoplastic lesions/normal tissue were examined by Wilcoxon signed-rank test and for all the other 2-group comparisons the Mann-Whitney U test was used. Most of the adenomas studied belonged to clinical specimens showing either tubular or villous low-grade dysplasia and an enrichment of Fusobacterium relative to paired normal tissue was not found (P = .180). In the carcinoma group, 57% of samples displayed a positive status for this bacterium with the highest burden of detectable Fusobacterium belonging to a specimen with positive regional lymph node metastasis. This is the first Portuguese study confirming a trend toward an overabundance of Fusobacterium in colorectal carcinomas compared to adenomas and paired samples of normal-looking mucosa, in keeping with the role of this bacterium in colorectal carcinogenesis. Further studies are needed to elucidate the relevance of Fusobacterium detection for the prevention and treatment of colorectal cancer.

Gut microbiome and aging: Physiological and mechanistic insights

The development of human gut microbiota begins as soon as the neonate leaves the protective environment of the uterus (or maybe in-utero) and is exposed to innumerable microorganisms from the mother as well as the surrounding environment. Concurrently, the host responses to these microbes during early life manifest during the development of an otherwise hitherto immature immune system. The human gut microbiome, which comprises an extremely diverse and complex community of microorganisms inhabiting the intestinal tract, keeps on fluctuating during different stages of life. While these deviations are largely natural, inevitable and benign, recent studies show that unsolicited perturbations in gut microbiota configuration could have strong impact on several features of host health and disease. Our microbiota undergoes the most prominent deviations during infancy and old age and, interestingly, our immune health is also in its weakest and most unstable state during these two critical stages of life, indicating that our microbiota and health develop and age hand-in-hand. However, the mechanisms underlying these interactions are only now beginning to be revealed. The present review summarizes the evidences related to the age-associated changes in intestinal microbiota and vice-versa, mechanisms involved in this bi-directional relationship, and the prospective for development of microbiota-based interventions such as probiotics for healthy aging.

Contribution of bacterial pathogens to evoking serological disease markers and aggravating disease activity in rheumatoid arthritis

Commensal bacteria and their pathogenic components in the gastrointestinal tract and oral cavity may play pathological roles in autoimmune diseases. To study the possible involvement of bacterial pathogens in autoimmune diseases, IgG and IgA antibodies against pathogenic components produced by three strains of commensal bacteria, Escherichia coli-lipopolysaccharide (E. coli-LPS), Porphyromonas gingivalis-LPS (Pg-LPS) and peptidoglycan polysaccharide (PG-PS) from Streptococcus pyogenes, were determined by an improved ELISA system for sera from two groups of patients with rheumatoid arthritis (RA), who met rapid radiographic progression (RRP) criteria and non-RRP, and compared to normal (NL) controls. Antibody responses to these bacterial pathogens are unique and consistent in individuals, and no fundamental difference was observed between RA and NL controls. Despite the similar antibody responses to pathogens, lower IgG or higher IgA and consequent higher IgA/IgG antibody ratio among the patients with RA related to disease marker levels and disease activity. Peculiarly, the IgA/IgG anti-Pg-LPS antibody ratio resulted from lower IgG and higher IgA antibody responses to Pg-LPS strongly correlated not only with rheumatoid factor (RF), but also correlated with erythrocyte sedimentation rate (ESR), C-reactive protein (CRP) and disease activity score of 28 joints with ESR (DAS28-ESR) in the RRP group. In contrast, the IgA/IgG anti-E. coli-LPS and anti-PG-PS antibody ratio correlated or tended to correlate with RF, ESR, CRP, and DAS28-ESR in the non-RRP group, whereas either the IgG or IgA anti-Pg-LPS antibody levels and consequent IgA/IgG anti-Pg-LPS antibody ratio did not correlate with any clinical marker levels in this group. Notably, anti-circular-citrullinated peptide (CCP) antibody levels, which did not correlate with either IgG or IgA antibody levels to any pathogens, did not correlate with severity of arthritis in both RRP and non-RRP. Taken together, we propose that multiple environmental pathogens, which overwhelm the host antibody defense function, contribute independently or concomitantly to evoking disease makers and aggravating disease activity, and affect disease outcomes.

TRIAL REGISTRATION

UMIN CTR UMIN000012200.

The Role of Bacteria, Probiotics and Diet in Irritable Bowel Syndrome

Irritable bowel syndrome is a highly prevalent gastrointestinal disorder that threatens the quality of life of millions and poses a substantial financial burden on healthcare systems around the world. Intense research into the human microbiome has led to fascinating discoveries which directly and indirectly implicate the diversity and function of this occult organ in irritable bowel syndrome (IBS) pathophysiology. The benefit of manipulating the gastrointestinal microbiota with diet and probiotics to improve symptoms has been demonstrated in a wealth of both animal and human studies. The positive and negative mechanistic roles bacteria play in IBS will be explored and practical probiotic and dietary choices offered.

The "Gut Feeling": Breaking Down the Role of Gut Microbiome in Multiple Sclerosis

Multiple sclerosis (MS) is a chronic neuroinflammatory disease of the central nervous system with unknown etiology. Recently, the gut microbiota has emerged as a potential factor in the development of MS, with a number of studies having shown that patients with MS exhibit gut dysbiosis. The gut microbiota helps the host remain healthy by regulating various functions, including food metabolism, energy homeostasis, maintenance of the intestinal barrier, inhibition of colonization by pathogenic organisms, and shaping of both mucosal and systemic immune responses. Alteration of the gut microbiota, and subsequent changes in its metabolic network that perturb this homeostasis, may lead to intestinal and systemic disorders such as MS. Here we discuss the findings of recent MS microbiome studies and potential mechanisms through which gut microbiota can predispose to, or protect against, MS. These findings highlight the need of an improved understanding of the interactions between the microbiota and host for developing therapies based on gut commensals with which to treat MS.

Unravelling methanogenesis in ruminants, horses and kangaroos: the links between gut anatomy, microbial biofilms and host immunity

The present essay aims to resolve the question as to why macropod marsupials (e.g. kangaroos and wallabies, hereinafter termed ‘macropods) and horses produce much less methane (CH4) than do ruminants when digesting the same feed. In herbivores, gases produced during fermentation of fibrous feeds do not pose a major problem in regions of the gut that have mechanisms to eliminate them (e.g. eructation in the rumen and flatus in the lower bowel). In contrast, gas pressure build-up in the tubiform forestomach of macropods or in the enlarged tubiform caecum of equids would be potentially damaging. It is hypothesised that, to prevent this problem, evolution has favoured development of controls over gut microbiota that enable enteric gas production (H2 and CH4) to be differently regulated in the forestomach of macropods and the caecum of all three species, from the forestomach of ruminants. The hypothesised regulation depends on interactions between their gut anatomy and host-tissue immune responses that have evolved to modify the species composition of their gut microbiota which, importantly, are mainly in biofilms. Obligatory H2 production during forage fermentation is, thus, captured in CH4 in the ruminant where ruminal gases are readily released by eructation, or in acetate in the macropod forestomach and equid caecum–colon where a build-up in gas pressure could potentially damage these organs. So as to maintain appropriate gut microbiota in different species, it is hypothesised that blind sacs at the cranial end of the haustral anatomy of the macropod forestomach and the equid caecum are sites of release of protobiofilm particles that develop in close association with the mucosal lymphoid tissues. These tissues release immune secretions such as antimicrobial peptides, immunoglobulins, innate lymphoid cells and mucin that eliminate or suppress methanogenic Archaea and support the growth of acetogenic microbiota. The present review draws on microbiological studies of the mammalian gut as well as other microbial environments. Hypotheses are advanced to account for published findings relating to the gut anatomy of herbivores and humans, the kinetics of digesta in ruminants, macropods and equids, and also the composition of biofilm microbiota in the human gut as well as aquatic and other environments where the microbiota exist in biofilms.

From homeostasis to pathology: decrypting microbe-host symbiotic signals in the intestinal crypt

Metagenomic analysis of the human intestinal microbiome has provided a wealth of information that allowed an exceptionally detailed description of its microbial content and physiological potential. It also set the basis for studies allowing correlation of alterations in the balance of this microbiota and the occurrence of a certain number of emerging diseases, such as inflammatory bowel diseases, obesity and diabetes, and possibly colorectal cancer. The time has come to give the intestinal microbiota in symbiosis with its host an experimental dimension. This brief review summarizes our attempt at developing a cellular microbiology of the mutualistic symbiosis established between the gut microbiota and the host intestinal surface. Particular attention is paid to the intestinal crypt, due to its role in epithelial regeneration.This article is part of the themed issue 'The new bacteriology'.

Influence of vitamin D on key bacterial taxa in infant microbiota in the KOALA Birth Cohort Study

Vitamin D has immunomodulatory properties giving it the potential to affect microbial colonization of the intestinal tract. We investigated whether maternal vitamin D supplemention, maternal plasma 25-hydroxyvitamin D concentration, or direct supplementation of the infant influences key bacterial taxa within microbiota of one month old infants. Infant and maternal vitamin D supplement use was ascertained via questionnaires. Maternal plasma 25-hydroxyvitamin D was determined at approximately the 36^th week of pregnancy. In 913 one month old infants in the prospective KOALA Birth Cohort Study, fecal Bifidobacterium spp., Escherichia coli, Clostridium difficile, Bacteroides fragilis group, Lactobacillus spp. and total bacteria were quantified with real-time polymerase chain reaction assays targeting 16S rRNA gene sequences. The association between vitamin D exposure and prevalence or abundance of a specific bacterial group or species was analyzed using logistic or linear regression, respectively. There was a statistically significant negative linear trend between counts of Bifidobacterium spp. and levels of maternal vitamin D supplementation and maternal 25-hydroxyvitamin D quintiles, respectively. In addition, a positive linear trend between quintile groups and B. fragilis group counts was observed. Lower counts of C. difficile were associated with vitamin D supplementation of breast fed infants whose mothers were more likely to adhere to an alternative lifestyle in terms of, e.g., dietary habits. These data suggest that vitamin D influences the abundance of several key bacterial taxa within the infant microbiota. Given that intestinal microbiotic homeostasis may be an important factor in the prevention of immune mediated diseases and that vitamin D status is a modifiable factor, further investigation of the impact of postnatal vitamin D supplementation should be conducted in older infants.

In vitro chlorhexidine release from alginate based microbeads for periodontal therapy

Periodontitis is one of the most common infectious diseases globally that, if untreated, leads to destruction of the tooth supporting tissues and finally results in tooth loss. Evidence shows that standard procedures as mechanical root cleaning could be supported by further treatment options such as locally applied substances. Due to gingival crevicular fluid flow, substances are commonly washed out off the periodontal pockets. The evaluation of administration techniques and the development of local drug releasing devices is thus an important aspect in periodontal research. This study describes the development and examination of a new alginate based, biodegradable and easily applicable drug delivery system for chlorhexidine (CHX). Different micro beads were produced and loaded with CHX and the release profiles were investigated by high performance liquid chromatography (HPLC). The in vitro-demonstrated release of CHX from alginate based beads shows comparable releasing characteristics as clinically approved systems. Yet many characteristics of this new delivery system show to be favourable for periodontal therapy. Easy application by injection, low production costs and multifunctional adaptions to patient related specifics may improve the usage in routine care.

Role of sex hormones and the vaginal microbiome in susceptibility and mucosal immunity to HIV-1 in the female genital tract

While the prevalence of Human immunodeficiency virus-1 (HIV-1) infection has stabilized globally, it continues to be the leading cause of death among women of reproductive age. The majority of new infections are transmitted heterosexually, and women have consistently been found to be more susceptible to HIV-1 infection during heterosexual intercourse compared to men. This emphasizes the need for a deeper understanding of how the microenvironment in the female genital tract (FGT) could influence HIV-1 acquisition. This short review focuses on our current understanding of the interplay between estrogen, progesterone, and the cervicovaginal microbiome and their immunomodulatory effects on the FGT. The role of hormonal contraceptives and bacterial vaginosis on tissue inflammation, T cell immunity and HIV-1 susceptibility is discussed. Taken together, this review provides valuable information for the future development of multi-purpose interventions to prevent HIV-1 infection in women.

SIgA表达功能及其在肠道疾病的作用

免疫球蛋白A(immunoglobulin A, IgA)在黏膜的免疫功能中起关键作用, 是维持肠道黏膜稳态的重要物质. 分泌型IgA(secretory IgA, SIgA)的分泌组分保护免疫球蛋白不被蛋白水解酶降解, SIgA在肠道内各种免疫因子、免疫细胞以及其他免疫球蛋白的参与下完成肠道内的免疫监视、免疫自稳、免疫调控. 本文主要就肠道中SIgA的结构、合成转运、分泌调节、作用和其相关临床疾病的研究进展作一综述.