Immune-Microbiota Interactions: Dysbiosis as a Global Health Issue

Early-life factors shaping the gut microbiota of Common buzzard nestlings

BACKGROUND

Exploring the dynamics of gut microbiome colonisation during early-life stages is important for understanding the potential impact of microbes on host development and fitness. Evidence from model organisms suggests a crucial early-life phase when shifts in gut microbiota can lead to immune dysregulation and reduced host condition. However, our understanding of gut microbiota colonisation in long-lived vertebrates, especially during early development, remains limited. We therefore used a wild population of common buzzard nestlings (Buteo buteo) to investigate connections between the early-life gut microbiota colonisation, environmental and host factors.

RESULTS

We targeted both bacterial and eukaryotic microbiota using the 16S and 28S rRNA genes. We sampled the individuals during early developmental stages in a longitudinal design. Our data revealed that age significantly affected microbial diversity and composition. Nest environment was a notable predictor of microbiota composition, with particularly eukaryotic communities differing between habitats occupied by the hosts. Nestling condition and infection with the blood parasite Leucocytozoon predicted microbial community composition.

CONCLUSION

Our findings emphasise the importance of studying microbiome dynamics to capture changes occurring during ontogeny. They highlight the role of microbial communities in reflecting host health and the importance of the nest environment for the developing nestling microbiome. Overall, this study contributes to understanding the complex interplay between microbial communities, host factors, and environmental variables, and sheds light on the ecological processes governing gut microbial colonisation during early-life stages.

Peri-weaning cholera toxin consumption suppresses chemically-induced carcinogenesis in mice

Gastrointestinal bacteria are known to have an impact on local and systemic immunity, and consequently either promote or suppress cancer development. Following the notion that perinatal bacterial exposure might confer immune system competency for life, we investigated whether early-life administration of cholera-toxin (CT), a protein exotoxin of the small intestine pathogenic bacterium Vibrio cholerae, may shape local and systemic immunity to impart a protective effect against tumor development in epithelia distantly located from the gut. For that, newborn mice were orally treated with low non-pathogenic doses of CT and later challenged with the carcinogen 7,12-dimethylbenzanthracene (DMBA), known to cause mainly mammary, but also skin, lung and stomach cancer. Our results revealed that CT suppressed the overall incidence and multiplicity of tumors, with varying efficiencies among cancer types, and promoted survival. Harvesting mouse tissues at an earlier time-point (105 instead of 294 days), showed that CT does not prevent preneoplastic lesions per se but it rather hinders their evolution into tumors. CT pretreatment universally increased apoptosis in the cancer-prone mammary, lung and nonglandular stomach, and altered the expression of several cancer-related molecules. Moreover, CT had a long-term effect on immune system cells and factors, the most prominent being the systemic neutrophil decrease. Finally, CT treatment significantly affected gut bacterial flora composition, leading among others to a major shift from Clostridia to Bacilli class abundance. Overall, these results support the notion that early-life CT consumption is able to affect host's immune, microbiome and gene expression profiles toward the prevention of cancer.

Microbiota Alterations in Lung, Ileum, and Colon of Guinea Pigs with Cough Variant Asthma

Alterations in the microbiota composition, or ecological dysbiosis, have been implicated in the development of various diseases, including allergic diseases and asthma. Examining the relationship between microbiota alterations in the host and cough variant asthma (CVA) may facilitate the discovery of novel therapeutic strategies. To elucidate the diversity and difference of microbiota across three ecological niches, we performed 16S rDNA amplicon sequencing on lung, ileum, and colon samples. We assessed the levels of interleukin-12 (IL-12) and interleukin-13 (IL-13) in guinea pig bronchoalveolar lavage fluid using the enzyme-linked immunosorbent assay (ELISA). We applied Spearman's analytical method to evaluate the correlation between microbiota and cytokines. The results demonstrated that the relative abundance, α-diversity, and β-diversity of the microbial composition of the lung, ileum, and colon varied considerably. The ELISA results indicated a substantial increase in the level of IL-13 and a decreasing trend in the level of IL-12 in the CVA guinea pigs. The Spearman analysis identified a correlation between Mycoplasma, Faecalibaculum, and Ruminococcus and the inflammatory factors in the CVA guinea pigs. Our guinea pig model showed that core microorganisms, such as Mycoplasma in the lung, Faecalibaculum in the ileum, and Ruminococcus in the colon, may play a crucial role in the pathogenesis of CVA. The most conspicuous changes in the ecological niche were observed in the guinea pig ileum, followed by the lung, while relatively minor changes were observed in the colon. Notably, the microbial structure of the ileum niche approximated that of the colon niche. Therefore, the results of this study suggest that CVA development is closely related to the dysregulation of ileal, lung, and colon microbiota and the ensuing inflammatory changes in the lung.

Metabolomics analysis in saliva from periodontally healthy, gingivitis and periodontitis patients

OBJECTIVE

The aim of this study was to investigate metabolomics markers in the saliva of patients with periodontal health, gingivitis and periodontitis.

BACKGROUND

The use of metabolomics for diagnosing and monitoring periodontitis is promising. Although several metabolites have been reported to be altered by inflammation, few studies have examined metabolomics in saliva collected from patients with different periodontal phenotypes.

METHODS

Saliva samples collected from a total of 63 patients were analysed by nuclear magnetic resonance (NMR) followed by ELISA for interleukin (IL)-1β. The patient sample, well-characterised clinically, included periodontal health (n = 8), gingivitis (n = 19) and periodontitis (n = 36) cases, all non-smokers and not diabetic.

RESULTS

Periodontal diagnosis (healthy/gingivitis/periodontitis) was not associated with any salivary metabolites in this exploratory study. Periodontal staging showed nominal associations with acetoin (p = .030) and citrulline (p = .047). Among other investigated variables, the use of systemic antibiotics in the previous 3 months was associated with higher values of the amino acids taurine, glycine and ornithine (p = .002, p = .05 and p = .005, respectively, at linear regression adjusted for age, gender, ethnicity, body mass index and staging).

CONCLUSION

While periodontal staging was marginally associated with some salivary metabolites, other factors such as systemic antibiotic use may have a much more profound effect on the microbial metabolites in saliva. Metabolomics in periodontal disease is still an underresearched area that requires further observational studies on large cohorts of patients, aiming to obtain data to be used for clinical translation.

Effect of a High-Fat Diet and Probiotic Supplementation on the Gut Microbiota of Maternal Mice at Term Pregnancy and Offspring at Three-Week Postpartum

The effects of probiotics on the gut microbiota in maternal mice-fed high-fat diet (HFD) during pregnancy and offspring are still unknown. We aimed to evaluate the effect of high-fat diet and probiotic supplementation on the gut microbiota of maternal mice at term pregnancy and offspring at three-week postpartum. Female pregnant Kunming mice were randomly divided into four groups: mice on a control diet (MC), mice on HFD (MHF), mice on a control diet and probiotics (MCP), and mice on HFD and probiotics (MHFP). The result showed that MHF had significantly reduced Bacteroidetes and Muribaculaceae (P < 0.05) and increased Firmicutes/Bacteroidetes ratio vs. MC. Lachnospiraceae_NK4A136_group and Alistipes reduced (P < 0.05), and Firmicutes/Bacteroidetes ratio significantly increased in MCP vs. MC. There was no significant difference between MHF and MHFP. Higher levels of Prevotella, Prevotellaceae, and Streptococcaceae were found in mice offspring on HFD (OHF) vs. mice offspring on a control diet (OC) (P < 0.05, respectively). Bacteroidia, Bacteroidota, Bacteroidales, and Muribaculaceae decreased markedly in mice offspring on a control diet and probiotics (OCP) vs. OC (P < 0.05, respectively), while Firmicutes, Lactobacillales, Lactobacillaceae, and Lactobacillus significantly increased in OCP (P < 0.05, respectively). There was no significant difference between the OHF and mice offspring on HFD and probiotics (OHFP). The findings suggest that the gut microbial composition of pregnant mice and offspring were altered to some extent due to HFD or probiotic intervention. Further, maternal mice on HFD and offspring were less affected by probiotic supplementation.

Undaria pinnatifida fucoidan ameliorates dietary fiber deficiency-induced inflammation and lipid abnormality by modulating mucosal microbiota and protecting intestinal barrier integrity

Dietary fiber deficiency (FD) is a new public health concern, with limited understanding of its impact on host energy requirements and health. In this study, the effect of fucoidan from Undaria pinnatifida (UPF) on FD-induced alterations of host physiological status was analyzed in mice. UPF increased colon length and cecum weight, reduced liver index, and modulated serum lipid metabolism primarily involving glycerophospholipid and linoleic acid metabolism in FD-treated mice. UPF protected against FD-induced destruction of intestinal barrier integrity by upregulating the expression levels of tight junction proteins and mucin-related genes. UPF alleviated FD-induced intestinal inflammation by reducing the levels of inflammation-related factors, such as interleukin-1β, tumor necrosis factor-α, and lipopolysaccharides, and relieving oxidative stress. The underlying mechanism can be closely associated with modulation of gut microbiota and metabolites, such as a reduction of Proteobacteria and an increase in short chain fatty acids. The in vitro model showed that UPF mitigated H2O2-induced oxidative stress and apoptosis in IEC-6 cells, indicating its potential as a therapeutic agent for inflammatory bowel disorders. This study suggests that UPF can be developed as a fiber supplement to benefit host health by modulating gut microbiota and metabolites and protecting intestinal barrier functions.

Mechanism and implications of pro-nature physical activity in antagonizing psychological stress: the key role of microbial-gut-brain axis

Appropriate physical activities and a biodiversity-rich environment are conducive to the relief of psychological stress, and pro-nature physical activities are a combination of the two, which has good application potential in antagonizing psychological stress, but the intervention mechanism is still unclear. The microbiota-gut-brain axis is cyclically associated with psychological stress, and psychological stress can affect the microbiota through the gut-brain pathway, and conversely, the microbiota can also affect the psychological stress-induced symptoms. It is suggested that the microbe-gut-brain axis may provide a new perspective and target for the treatment of psychological stress-related diseases. Pro-nature physical activity can improve the number of Firmicutes, short-chain fatty acids, Akkermansia bacteria, and the gut-brain barrier and further affect the HPA axis, BDNF, and serotonin pathways of gut-brain two-way communication, thereby maintaining the body's homeostasis and reducing antagonistic psychological stress. According to the comprehensive influence of physical activities on the microbiota-gut-brain axis, a "green + exercise prescription hypothesis" in line with the holistic medical concept is revealed, which is expected to be effective in the prevention, alleviation, and treatment of irritable bowel syndrome and neurodegenerative diseases. It provides new means for treating psychological stress-related diseases such as mental disorders and mood disorders. In addition, it enlightens the construction of green infrastructure that is conducive to the diversified contact of microorganisms in outdoor physical activities venues and induces healthy interaction between the human body and the microbial population in the natural ecology. However, the current research is still in its early stages, and the intervention effect and mechanism of pro-nature physical activities need further demonstration in the future.

Effects of Modified Dietary Fiber from Fresh Corn Bracts on Obesity and Intestinal Microbiota in High-Fat-Diet Mice

The effects of insoluble dietary fiber from fresh corn bracts modified by dynamic high-pressure micro-fluidization (DHPM) on the pathological characteristics of obesity, intestinal microflora distribution and production of short-chain fatty acids in high-fat-diet C57BL/6 mice were evaluated. The results show that the DHPM-modified dietary fiber from fresh corn bracts significantly reduces weight gain, insulin resistance and oxidative damage caused by a high-fat diet, and promotes the production of SCFAs, especially acetic acid, propionic acid and butyric acid. These modified dietary fibers also change the proportion of different types of bacteria in the intestinal microflora of mice, reduce the ratio of Firmicutes and Bacteroidota and promote the proliferation of Bifidobacteriales. Therefore, the DHPM-modified dietary fiber from fresh corn bracts can be used as a good intestinal microbiota regulator to promote intestinal health, thereby achieving the role of preventing and treating obesity.

Human skin bacterial microbiota homeostasis: A delicate balance between health and disease

As the largest organ of the body, the skin acts as a barrier to prevent diseases and harbors a variety of beneficial bacteria. Furthermore, the skin bacterial microbiota plays a vital role in health and disease. Disruption of the barrier or an imbalance between symbionts and pathogens can lead to skin disorders or even systemic diseases. In this review, we first provide an overview of research on skin bacterial microbiota and human health, including the composition of skin bacteria in a healthy state, as well as skin bacterial microbiota educating the immune system and preventing the invasion of pathogens. We then discuss the diseases that result from skin microbial dysbiosis, including atopic dermatitis, common acne, chronic wounds, psoriasis, viral transmission, cutaneous lupus, cutaneous lymphoma, and hidradenitis suppurativa. Finally, we highlight the progress that utilizes skin microorganisms for disease therapeutics, such as bacteriotherapy and skin microbiome transplantation. A deeper knowledge of the interaction between human health and disease and the homeostasis of the skin bacterial microbiota will lead to new insights and strategies for exploiting skin bacteria as a novel therapeutic target.

Fine-scale spatial variation shape fecal microbiome diversity and composition in black-tailed prairie dogs (Cynomys ludovicianus)

BACKGROUND

Host associated gut microbiota are important in understanding the coevolution of host-microbe, and how they may help wildlife populations to adapt to rapid environmental changes. Mammalian gut microbiota composition and diversity may be affected by a variety of factors including geographic variation, seasonal variation in diet, habitat disturbance, environmental conditions, age, and sex. However, there have been few studies that examined how ecological and environmental factors influence gut microbiota composition in animals' natural environments. In this study, we explore how host habitat, geographical location and environmental factors affect the fecal microbiota of Cynomys ludovicianus at a small spatial scale. We collected fecal samples from five geographically distinct locations in the Texas Panhandle classified as urban and rural areas and analyzed them using high throughput 16S rRNA gene amplicon sequencing.

RESULTS

The results showed that microbiota of these fecal samples was largely dominated by the phylum Bacteroidetes. Fecal microbiome diversity and composition differed significantly across sampling sites and habitats. Prairie dogs inhabiting urban areas showed reduced fecal diversity due to more homogenous environment and, likely, anthropogenic disturbance. Urban prairie dog colonies displayed greater phylogenetic variation among replicates than those in rural habitats. Differentially abundant analysis revealed that bacterial species pathogenic to humans and animals were highly abundant in urban areas which indicates that host health and fitness might be negatively affected. Random forest models identified Alistipes shahii as the important species driving the changes in fecal microbiome composition. Despite the effects of habitat and geographic location of host, we found a strong correlation with environmental factors and that- average maximum temperature was the best predictor of prairie dog fecal microbial diversity.

CONCLUSIONS

Our findings suggest that reduction in alpha diversity in conjunction with greater dispersion in beta diversity could be indicative of declining host health in urban areas; this information may, in turn, help determine future conservation efforts. Moreover, several bacterial species pathogenic to humans and other animals were enriched in prairie dog colonies near urban areas, which may in turn adversely affect host phenotype and fitness.

Dietary niche breadth influences the effects of urbanization on the gut microbiota of sympatric rodents

Cities are among the most extreme forms of anthropogenic ecosystem modification, and urbanization processes exert profound effects on animal populations through multiple ecological pathways. Increased access to human‐associated food items may alter species' foraging behavior and diet, in turn modifying the normal microbial community of the gastrointestinal tract (GIT), ultimately impacting their health. It is crucial we understand the role of dietary niche breadth and the resulting shift in the gut microbiota as urban animals navigate novel dietary resources. We combined stable isotope analysis of hair and microbiome analysis of four gut regions across the GIT to investigate the effects of urbanization on the diet and gut microbiota of two sympatric species of rodents with different dietary niches: the omnivorous large Japanese field mouse (Apodemus speciosus) and the relatively more herbivorous gray red‐backed vole (Myodes rufocanus). Both species exhibited an expanded dietary niche width within the urban areas potentially attributable to novel anthropogenic foods and altered resource availability. We detected a dietary shift in which urban A. speciosus consumed more terrestrial animal protein and M. rufocanus more plant leaves and stems. Such changes in resource use may be associated with an altered gut microbial community structure. There was an increased abundance of the presumably probiotic Lactobacillus in the small intestine of urban A. speciosus and potentially pathogenic Helicobacter in the colon of M. rufocanus. Together, these results suggest that even taxonomically similar species may exhibit divergent responses to urbanization with consequences for the gut microbiota and broader ecological interactions.

Biodiversity for resilience-What is needed for allergic children

What is needed for our children facing unprecedented challenges of modern time? Biodiversity, both for immunological and psychological well-being and resilience. That is also the keyword for the children with allergies and asthma. The cultural evolution with advanced technology and medicine along with major move to urban environment has profoundly changed our lifestyle and surroundings. We are increasingly disconnected from our evolutionary home, soil, natural waters, and air we used to breathe. The ecosystem of human body and mind has been tested, survived, and evolved closely in relation with other ecosystems. For balance and tolerance, immune regulatory circuits need training by microbes, biogenic chemicals, and close relation to natural environment throughout life. This is addressed by the biodiversity hypothesis of tolerance/resilience for health, supported by the pioneering real-world interventions and a few controlled studies. No need to go "back to nature," but we must take natural elements back to our everyday life to breathe, eat, drink, and touch. The change for better is plausible and cost-effective, as shown by the Finnish and other European initiatives, but needs contribution of the whole society.

High-Salt Diet Induces Depletion of Lactic Acid-Producing Bacteria in Murine Gut

Dietary habits are amongst the main factors that influence the gut microbiome. Accumulating evidence points to the impact of a high-salt diet (HSD) on the composition and function of the intestinal microbiota, immune system and disease. In the present study, we thus investigated the effects of different NaCl content in the food (0.03%/sodium deficient, 0.5%/control, 4% and 10% NaCl) on the gut microbiome composition in mice. The bacterial composition was profiled using the 16S ribosomal RNA (rRNA) gene amplicon sequencing. Our results revealed that HSD led to distinct gut microbiome compositions compared to sodium-deficient or control diets. We also observed significant reduction in relative abundances of bacteria associated with immuno-competent short-chain fatty acid (SCFA) production (Bifidobacterium, Faecalibaculum, Blautia and Lactobacillus) in HSD-fed mice along with significant enrichment of Clostridia, Alistipes and Akkermansia depending on the sodium content in food. Furthermore, the predictive functional profiling of microbial communities indicated that the gut microbiota found in each category presents differences in metabolic pathways related to carbohydrate, lipid and amino acid metabolism. The presented data show that HSD cause disturbances in the ecological balance of the gastrointestinal microflora primarily through depletion of lactic acid-producing bacteria in a dose-dependent manner. These findings may have important implications for salt-sensitive inflammatory diseases.

A Journey on the Skin Microbiome: Pitfalls and Opportunities

The human skin microbiota is essential for maintaining homeostasis and ensuring barrier functions. Over the years, the characterization of its composition and taxonomic diversity has reached outstanding goals, with more than 10 million bacterial genes collected and cataloged. Nevertheless, the study of the skin microbiota presents specific challenges that need to be addressed in study design. Benchmarking procedures and reproducible and robust analysis workflows for increasing comparability among studies are required. For various reasons and because of specific technical problems, these issues have been investigated in gut microbiota studies, but they have been largely overlooked for skin microbiota. After a short description of the skin microbiota, the review tackles methodological aspects and their pitfalls, covering NGS approaches and high throughput culture-based techniques. Recent insights into the "core" and "transient" types of skin microbiota and how the manipulation of these communities can prevent or combat skin diseases are also covered. Finally, this review includes an overview of the main dermatological diseases, the changes in the microbiota composition associated with them, and the recommended skin sampling procedures. The last section focuses on topical and oral probiotics to improve and maintain skin health, considering their possible applications for skin diseases.

The role of microbiota and enteroendocrine cells in maintaining homeostasis in the human digestive tract

The microbiota is a heterogeneous ecosystem consisting of diverse microorganisms unique to an individual, playing a crucial role in maintaining human body homeostasis. The microbiota, as a suggested endocrine organ, is also capable of producing and regulating hormones, playing an important role in food processing, synthesis of vitamins, pathogen displacement, and influencing functions of distant systems and organs. The efficient connections between the brain and intestines and microbiota ensure the maintenance of the digestive tract homeostasis, with the bidirectional brain and gut axis playing an important role in the regulation of digestion. Enteroendocrine cells (EECs) are a fascinating example of highly specified cells scattered throughout the gastrointestinal (GI) tract. They produce and release signaling molecules (hormones), thus modulate homeostatic functions. EECs are believed to be crucial sensors of gut microbiota or/and microbial metabolites, secreting peptide hormones and cytokines in response to them. The diet, microbiota, and EECs are inevitably dependent on one another, thus together (nutrients, microbiota, enterohormones) affect metabolism. This manuscript reviews the role of various components of the brain-gut axis in digestive and absorption processes, as well as the maintenance of digestive tract homeostasis and the consequences of disturbances in the individual components of this axis.

A world of inflammation: the need for ecological solutions that co-benefit people, place and planet

The ecology of the early environment - including microbial diversity, nutrition, nature, social interactions and the totality of exposures in the wider "exposome" - have life-long implications for all aspects of health and resilience. In particular, the emergence of "microbiome science" provides new evidence for vital relationships between biodiversity and health at every level. New perspectives of ecological interdependence connect personal and planetary health; the human health crisis cannot be separated from the social, political and economic "ecosystems" otherwise driving dysbiosis (from its etymological root, "life in distress") at every level. Adverse changes in macroscale ecology - of food systems, lifestyle behaviours, socioeconomic disadvantage and environmental degradation - all impact the microbial systems sitting at the foundations of all ecosystems. In particular, changes in the function and composition of the human-associated microbiome have been implicated in the mounting global burden of noncommunicable diseases (NCDs), exacerbating inflammation and metabolic dysregulation through multiple pathways across the lifespan. This "dysbiotic drift" (adverse shifts in ecology at all scales) underscores the need for ecological approaches aimed at restoring symbiosis, balance and mutualism. While there is promise with supplement-based strategies (e.g. probiotics, prebiotics), it is essential to focus on upstream factors implicated in dysbiosis, including the health of wider environments, lifestyle, nature relatedness, and the social policies and practices which can facilitate or inhibit dysbiotic drift. This also calls for ambitious integrative approaches which not only define these interconnections, but also capitalize on them to create novel, collaborative and mutualistic solutions to our vast interdependent global challenges.

Breastfeeding promotes early neonatal regulatory T-cell expansion and immune tolerance of non-inherited maternal antigens

BACKGROUND

Breastfeeding is associated with long-term health benefits, such as a lower incidence of childhood infections, asthma, obesity and autoimmune disorders. However, little is known regarding how the maternal and neonatal immune systems interact after parturition when the neonate receives nutrition from maternal breast milk.

METHODS

We undertook a comparative analysis of immune repertoire and function at birth and 3 weeks of age in a cohort of 38 term neonates born by caesarean section grouped according to feeding method (breast milk versus formula). We used flow cytometry to study the immune phenotype in neonatal and maternal blood samples and mixed lymphocyte reactions to establish the proliferation response of neonatal versus maternal lymphocytes and vice versa. The microbiome of neonatal stool samples was also investigated using 16S rRNA sequencing.

RESULTS

We show that the proportion of regulatory T cells (Tregs) increases in this period and is nearly twofold higher in exclusively breastfed neonates compared with those who received formula milk only. Moreover, breastfed neonates show a specific and Treg-dependent reduction in proliferative T-cell responses to non-inherited maternal antigens (NIMA), associated with a reduction in inflammatory cytokine production. We also observed the enrichment of short chain fatty acid producing taxa (Veillonella and Gemella) in stool samples of exclusively breastfed neonates.

CONCLUSIONS

These data indicate that exposure of the neonate to maternal cells through breastfeeding acts to drive the maturation of Tregs and 'tolerizes' the neonate towards NIMA.

Protective Effects of Probiotics on Cognitive and Motor Functions, Anxiety Level, Visceral Sensitivity, Oxidative Stress and Microbiota in Mice with Antibiotic-Induced Dysbiosis

Accumulating clinical and preclinical data indicate a prominent role of gut microbiota in regulation of physiological functions. The gut-brain axis imbalance due to gut dysbiosis is associated with a range of neurodegenerative diseases. Probiotics were suggested not only to restore intestinal dysbiosis but also modulate stress response and improve mood and anxiety symptoms. In this study, we assessed the effects of probiotic lactobacilli on behavioral reactions, the level of oxidative stress and microbiota content in mice administered to broad-spectrum antibiotics. Our study demonstrates that antibiotic treatment of adolescent mice for two weeks resulted in higher mortality and lower weight gain and induced significant changes in behavior including lower locomotor and exploratory activity, reduced muscle strength, visceral hypersensitivity, higher level of anxiety and impaired cognitive functions compared to the control group. These changes were accompanied by decreased diversity and total amount of bacteria, abundance of Proteobacteria and Verrucomicrobia phyla, and reduced Firmicutes/Bacteroides ratio in the gut microbiota. Moreover, a higher level of oxidative stress was found in brain and skeletal muscle tissues of mice treated with antibiotics. Oral administration of two Lactobacillus strains prevented the observed changes and improved not only microbiota content but also the behavioral alterations, suggesting a neuroprotective and antioxidant role of probiotics.

The Effect of Dietary Fibre on Gut Microbiota, Lipid Profile, and Inflammatory Markers in Patients with Type 2 Diabetes: A Systematic Review and Meta-Analysis of Randomised Controlled Trials

Background: A disequilibrium of the gut microbial community has been closely associated with systemic inflammation and metabolic syndromes including type 2 diabetes. While low fibre and high fat diets may lead to dysbiosis of the gut microbiome as a result of the loss of useful microbes, it has been reported that a high fibre diet may prevent the fermentation of protein and may promote eubiosis of gut microbiota. Aim: This review aims to evaluate the effect of dietary fibre (DF) on gut microbiota, lipid profile, and inflammatory markers in patients with type 2 diabetes. Methods: The PRISMA framework was relied on to conduct this systematic review and meta-analysis. Searches were carried out using electronic databases and reference list of articles. Results: Eleven studies were included in the systematic review, while ten studies were included in the meta-analysis. The findings revealed five distinct areas including the effects of DF on (a) gut microbiota (122 participants); (b) lipopolysaccharides (LPS, 79 participants) and lipopolysaccharides binding protein (LBP, 81 participants); (c) lipid profile; (d) inflammatory markers; and (e) body mass index (BMI, 319 participants). The relative abundance of Bifidobacterium increased by 0.73 (95% CI: 0.57, 0.89) in the DF group in contrast to the control (p < 0.05). With respect to LPS, the level was lower in the DF group than the control and the difference was significant (p < 0.05). The standardised mean difference for LPS was −0.45 (95% CI: −0.90, −0.01) although the difference between the two groups in relation to LBP was not significant (p = 0.08) and the mean difference was 0.92 (95% CI: −0.12, 1.95). While there was a decrease of −1.05 (95% CI: −2.07, −0.02) with respect to total cholesterol (356 participants) in the DF group as compared with the control (p < 0.05), both groups were not significantly different (p > 0.05) in the other lipid parameters. The difference between the groups was significant (p < 0.05) in relation to C-reactive protein, and the mean difference was 0.43 (95% CI: 0.02, 0.84). This could be due to the short duration of the included studies and differences in participants’ diets including the amount of dietary fibre supplements. However, the groups were not significantly different (p > 0.05) with respect to the other inflammatory markers. The meta-analysis of the BMI showed that the DF group decreased by −0.57 (95% CI: −1.02, −0.12) as compared with the control and this was significant (p < 0.01). Conclusion: DF significantly (p < 0.05) increased the relative abundance of Bifidobacterium and significantly decreased (p < 0.05) LPS, total cholesterol, and BMI as compared with the control. However, DF did not seem to have an effect that was significant on LBP, triglyceride, HDL cholesterol, LDL cholesterol, IL-6, TNF-α, adiponectin, and leptin. These findings have implications for public health in relation to the use of dietary fibre in nutritional interventions and as strategies for managing type 2 diabetes.

Reverse Microbiomics: A New Reverse Dysbiosis Analysis Strategy and Its Usage in Prediction of Autoantigens and Virulent Factors in Dysbiotic Gut Microbiomes From Rheumatoid Arthritis Patients

Alterations in the gut microbiome have been associated with various human diseases. Most existing gut microbiome studies stopped at the stage of identifying microbial alterations between diseased or healthy conditions. As inspired by reverse vaccinology (RV), we developed a new strategy called Reverse Microbiomics (RM) that turns this process around: based on the identified microbial alternations, reverse-predicting the molecular mechanisms underlying the disease and microbial alternations. Our RM methodology starts by identifying significantly altered microbiota profiles, performing bioinformatics analysis on the proteomes of the microbiota identified, and finally predicting potential virulence or protective factors relevant to a microbiome-associated disease. As a use case study, this reverse methodology was applied to study the molecular pathogenesis of rheumatoid arthritis (RA), a common autoimmune and inflammatory disease. Those bacteria differentially associated with RA were first identified and annotated from published data and then modeled and classified using the Ontology of Host-Microbiome Interactions (OHMI). Our study identified 14 species increased and 9 species depleted in the gut microbiota of RA patients. Vaxign was used to comparatively analyze 15 genome sequences of the two pairs of species: Gram-negative Prevotella copri (increased) and Prevotella histicola (depleted), as well as Gram-positive Bifidobacterium dentium (increased) and Bifidobacterium bifidum (depleted). In total, 21 auto-antigens were predicted to be related to RA, and five of them were previously reported to be associated with RA with experimental evidence. Furthermore, we identified 94 potential adhesive virulence factors including 24 microbial ABC transporters. While eukaryotic ABC transporters are key RA diagnosis markers and drug targets, we identified, for the first-time, RA-associated microbial ABC transporters and provided a novel hypothesis of RA pathogenesis. Our study showed that RM, by broadening the scope of RV, is a novel and effective strategy to study from bacterial level to molecular level factors and gain further insight into how these factors possibly contribute to the development of microbial alterations under specific diseases.

Understanding Asthma and Allergies by the Lens of Biodiversity and Epigenetic Changes

Exposure to different organisms (bacteria, mold, virus, protozoan, helminths, among others) can induce epigenetic changes affecting the modulation of immune responses and consequently increasing the susceptibility to inflammatory diseases. Epigenomic regulatory features are highly affected during embryonic development and are responsible for the expression or repression of different genes associated with cell development and targeting/conducting immune responses. The well-known, "window of opportunity" that includes maternal and post-natal environmental exposures, which include maternal infections, microbiota, diet, drugs, and pollutant exposures are of fundamental importance to immune modulation and these events are almost always accompanied by epigenetic changes. Recently, it has been shown that these alterations could be involved in both risk and protection of allergic diseases through mechanisms, such as DNA methylation and histone modifications, which can enhance Th2 responses and maintain memory Th2 cells or decrease Treg cells differentiation. In addition, epigenetic changes may differ according to the microbial agent involved and may even influence different asthma or allergy phenotypes. In this review, we discuss how exposure to different organisms, including bacteria, viruses, and helminths can lead to epigenetic modulations and how this correlates with allergic diseases considering different genetic backgrounds of several ancestral populations.

Systematic Review of Beef Protein Effects on Gut Microbiota: Implications for Health

The influence of diet on the gut microbiota is an emerging research area with significant impact on human health and disease. However, the effects of beef, the most consumed red meat in the United States, on gut microbial profile are not well studied. Following Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols, the objective of this systematic review was to conduct a rigorous and thorough review of the current scientific literature regarding the effects of beef protein and the resulting bioactivity of beef protein and amino acids on the gut microbiota, with the goal of identifying gaps in the literature and guiding future research priorities. Utilizing MEDLINE Complete, PubMed, ScienceDirect, Scopus, and Google Scholar databases, we conducted searches including terms and combinations of the following: animal protein, amino acid, beef, bioactive compounds, diet, health, microbiome, peptide, processed beef, and protein. We identified 131 articles, from which 15 were included in our review. The effects of beef on mouse and rat models were mostly consistent for the bacterial phylum level. Short-term (1-4-wk) beef intakes had little to no effect on microbial profiles in humans. Most studies utilized high beef feeding (240-380 g/d), and no study examined recommended amounts of protein [∼3.71 oz/d (105 g/d) meats, poultry, and eggs, or ∼26 oz/week (737 g/wk) from these food sources] according to US dietary guidelines. Additionally, the majority of animal and human studies with adverse findings examined the impact of beef in the context of a diet high in fat or sugar. In conclusion, an extensive gap exists in the literature regarding beef and the microbiota. More studies are necessary to elucidate the role of the microbiota following the consumption of beef, especially in interaction with other dietary compounds, and how beef preparation, processing, and cooking methods differentially influence the biological effects of beef on human health.

The role of short-chain fatty acids in immunity, inflammation and metabolism

Short-chain fatty acids (SCFAs) are carboxylic acids with carbon atom numbers less than 6, which are important metabolites of gut microbiome. Existing research shows that SCFAs play a vital role in the health and disease of the host. First, SCFAs are the key energy source for colon and ileum cells, and affect the intestinal epithelial barrier and defense functions by regulating related gene expression. Second, SCFAs regulate the function of innate immune cells to participate in the immune system, such as macrophages, neutrophils and dendritic cells. Third, SCFAs can also regulate the differentiation of T cells and B cells and the antigen-specific adaptive immunity mediated by them. Besides, SCFAs are raw materials for sugar and lipid synthesis, which provides a theoretical basis for studying the potential role of SCFAs in regulating energy homeostasis and metabolism. There are also studies showing that SCFAs inhibit tumor cell proliferation and promote apoptosis. In this article, we summarized in detail the role of SCFAs in immunity, inflammation and metabolism, and briefly introduced the role of SCFAs in tumor cell survival. It provides a systematic theoretical basis for the study of SCFAs as potential drugs to promote human health.

Deciphering Coral Disease Dynamics: Integrating Host, Microbiome, and the Changing Environment

Diseases of tropical reef organisms is an intensive area of study, but despite significant advances in methodology and the global knowledge base, identifying the proximate causes of disease outbreaks remains difficult. The dynamics of infectious wildlife diseases are known to be influenced by shifting interactions among the host, pathogen, and other members of the microbiome, and a collective body of work clearly demonstrates that this is also the case for the main foundation species on reefs, corals. Yet, among wildlife, outbreaks of coral diseases stand out as being driven largely by a changing environment. These outbreaks contributed not only to significant losses of coral species but also to whole ecosystem regime shifts. Here we suggest that to better decipher the disease dynamics of corals, we must integrate more holistic and modern paradigms that consider multiple and variable interactions among the three major players in epizootics: the host, its associated microbiome, and the environment. In this perspective, we discuss how expanding the pathogen component of the classic host-pathogen-environment disease triad to incorporate shifts in the microbiome leading to dysbiosis provides a better model for understanding coral disease dynamics. We outline and discuss issues arising when evaluating each component of this trio and make suggestions for bridging gaps between them. We further suggest that to best tackle these challenges, researchers must adjust standard paradigms, like the classic one pathogen-one disease model, that, to date, have been ineffectual at uncovering many of the emergent properties of coral reef disease dynamics. Lastly, we make recommendations for ways forward in the fields of marine disease ecology and the future of coral reef conservation and restoration given these observations.

Precision medicine in cow's milk allergy

PURPOSE OF REVIEW

The aim of this review is to describe the role of precision medicine in the diagnosis, treatment, and monitoring of cow's milk allergy.

RECENT FINDINGS

The development of 'omics' sciences in the field of food allergy has led to a better understanding of the allergenicity of cow's milk proteins and significant advances in the knowledge of the pathogenesis and mechanisms of cow's milk allergy. Omics-based technologies allow the practitioner to better differentiate cow's milk allergy subtypes and to predict cow's milk allergy (CMA) persistence over time. Precision medicine extends the role of the oral food challenge, to determine the individual's threshold doses, and to establish tolerance to baked milk products. Other than symptom relief, dietary strategies are currently being investigated for the potential to induce tolerance. Oral immunotherapy offers a treatment option for patients with severe and persistent IgE-mediated CMA. Individual baseline-immune profiles may be predictive of cow's milk oral immunotherapy safety and efficacy.Patient data derived from current technology, in combination with the patient's history, can be translated into treatments targeted at patient-tailored interventions.

SUMMARY

The identification of novel biomarkers may improve diagnostic accuracy and also predict patient responsiveness to treatments. Integration of patient data will become increasingly important as omics technologies become more widely used in the clinical setting.

Effect of long-term consumption of tea (Camellia sinensis L.) flower polysaccharides on maintaining intestinal health in BALB/c mice

Polysaccharides have various health-promoting functions. However, dietary polysaccharides cannot be digested by the human alimentary tract, thus the gut is the most important location where polysaccharides play their role. The effect of polysaccharides from tea (Camellia sinensis L.) flower (TFPS) on intestinal health was investigated in the present study. TFPS with the molecular weight of 1,316.29 kDa was prepared, and twenty 6-week-old BALB/c male mice were randomly allotted to a chow diet (normal control group, NC group) or with 200 mg/kg (body weight)/day of TFPS for 13 weeks (n = 10 each). Histomorphology observation of jejunum and colons showed that TFPS maintained the adequate gut barrier. qPCR analysis revealed that the expression of colonic tight junction proteins of claudin1 (1.29 ± 0.15 compared with 1.00 ± 0.13, P < 0.05) and claudin5 (2.91 ± 0.44 compared with 1.00 ± 0.27, P < 0.01) at mRNA level with a significant difference between TFPS supplement or not, while the expression of TLR4 and TNF-α mRNA was not changed statistically. 16S rDNA amplicons sequencing was applied to measure the compositions of gut microbiota from feces of mice. TFPS treatment exhibited similar relative abundances in Bacteroidetes and Firmicutes; however, it decreased the relative abundance of Akkermansia and increased that of Lactobacillus compared with the NC group. The contents of short-chain fatty acids after TFPS supplementation, both in cecal contents and feces, were significantly higher than those of the NC group. Besides, TFPS significantly increased IgA production. These results suggest that TFPS is beneficial to intestinal health and can improve intestinal adaptive immune tolerance. PRACTICAL APPLICATION: Dietary polysaccharides improve human intestinal health. Understanding the effect of TFPS, safe and healthy food components, on gut health increases the likelihood that TFPS will be developed as a functional food.

The effect of microbiome exposure at birth on pediatric outcomes using a twin cohort discordant for microbiome exposure at birth

Objective: Microbiome exposure at birth has been associated with long-term pediatric outcomes. However, it is difficult to determine if differences in outcomes are truly due to microbiome exposure at birth or other exposures after birth and in early infancy. Using a twin cohort, we sought to determine the association between length of exposure to the maternal vaginal-fecal microbiome and long-term pediatric health outcomes by comparing outcomes between presenting and nonpresenting twins born to women who labored.Methods: We performed a mail-based survey study of women in a single maternal-fetal medicine practice who delivered twin pregnancies ≥24 weeks. The survey study was sent to women when twins were between 2 and 10 years old to assess the long-term health outcomes, including any medical diagnoses or problems with grown and development. For this study, we included all women who labored, and we compared health outcomes for the presenting versus nonpresenting twin with the primary outcome being the development of asthma/reactive airway disease and allergies. The length of exposure to the maternal vaginal-fecal microbiome was measured using the time from rupture of membranes (ROM) to delivery of each twin. Chi-square and Student's t-test were used.Results: Two hundred fifty-seven sets of twins were eligible for analyses. The presenting twin had a longer time of ROM than the nonpresenting twin (617 ± 2408 min versus 2 ± 5 minutes, p < .001). There were no significant differences between health outcomes for the presenting versus nonpresenting twin in the overall cohort, including the development of asthma/reactive airway disease (9.3 versus 10.1%, p = .77) or allergies (12.5 versus 7.8%, p = .08). There were no differences in any outcomes when comparing the presenting versus nonpresenting twin for those twins delivered vaginally or by cesarean delivery.Conclusion: In twins born to women who labored and either delivered vaginally or via cesarean section, delivery order was not associated with any significant increase in defined adverse pediatric outcomes, including the development of asthma or allergies. Using twins as a model for microbiome exposure may help to elucidate the role of the maternal vaginal-fecal microbiome on long-term pediatric health outcomes.

Helsinki by nature: The Nature Step to Respiratory Health

Background

The Nature Step to Respiratory Health was the overarching theme of the 12th General Meeting of the Global Alliance against Chronic Respiratory Diseases (GARD) in Helsinki, August 2018. New approaches are needed to improve respiratory health and reduce premature mortality of chronic diseases by 30% till 2030 (UN Sustainable Development Goals, SDGs). Planetary health is defined as the health of human civilization and the state of the natural systems on which it depends. Planetary health and human health are interconnected, and both need to be considered by individuals and governments while addressing several SDGs.

Results

The concept of the Nature Step has evolved from innovative research indicating, how changed lifestyle in urban surroundings reduces contact with biodiverse environments, impoverishes microbiota, affects immune regulation and increases risk of NCDs. The Nature Step calls for strengthening connections to nature. Physical activity in natural environments should be promoted, use of fresh vegetables, fruits and water increased, and consumption of sugary drinks, tobacco and alcohol restricted. Nature relatedness should be part of everyday life and especially emphasized in the care of children and the elderly. Taking “nature” to modern cities in a controlled way is possible but a challenge for urban planning, nature conservation, housing, traffic arrangements, energy production, and importantly for supplying and distributing food. Actions against the well-known respiratory risk factors, air pollution and smoking, should be taken simultaneously.

Conclusions

In Finland and elsewhere in Europe, successful programmes have been implemented to reduce the burden of respiratory disorders and other NCDs. Unhealthy behaviour can be changed by well-coordinated actions involving all stakeholders. The growing public health concern caused by NCDs in urban surroundings cannot be solved by health care alone; a multidisciplinary approach is mandatory.

A biodiversity hypothesis

Biodiversity hypothesis states that contact with natural environments enriches the human microbiome, promotes immune balance and protects from allergy and inflammatory disorders. We are protected by two nested layers of biodiversity, microbiota of the outer layer (soil, natural waters, plants, animals) and inner layer (gut, skin, airways). The latter inhabits our body and is colonized from the outer layer. Explosion of human populations along with cultural evolution is profoundly changing our environment and lifestyle. Adaptive immunoregulatory circuits and dynamic homeostasis are at stake in the newly emerged urban surroundings. In allergy, and chronic inflammatory disorders in general, exploring the determinants of immunotolerance is the key for prevention and more effective treatment. Loss of immunoprotective factors, derived from nature, is a new kind of health risk poorly acknowledged until recently. The paradigm change has been implemented in the Finnish allergy programme (2008-2018), which emphasized tolerance instead of avoidance. The first results are promising, as allergy burden has started to reduce. The rapidly urbanizing world is facing serious biodiversity loss with global warming, which are interconnected. Biodiversity hypothesis of health and disease has societal impact, for example, on city planning, food and energy production and nature conservation. It has also a message for individuals for health and well-being: take nature close, to touch, eat, breathe, experience and enjoy. Biodiverse natural environments are dependent on planetary health, which should be a priority also among health professionals.

Probiotic Supplementation During Human Pregnancy Affects the Gut Microbiota and Immune Status

The consumption of probiotics and fermented foods has been very popular in recent decades. The primary aim of our study was to evaluate the effect of probiotics on the gut microbiota and the changes in inflammatory cytokines after an average of 6.7 weeks of probiotic administration among normal pregnant women. Thirty-two healthy pregnant women at 32 weeks of gestation were recruited and divided into two groups. The probiotic group ingested combined probiotics until after birth. The base characteristics of the probiotics and control groups showed no significant differences. The structure of the fecal microbiota at the genus level varied during the third trimester, and administration of probiotics had no influence on the composition of the fecal microbiota however, many highly abundant taxa and core microbiota at the genus level changed in the probiotic group when compared to the control group. The analysis of cytokines showed that IL-5, IL-6, TNF-α, and GM-CSF had equal levels between the baseline and control groups but were significantly increased after probiotic administration (baseline = control < probiotics). Additionally, levels of IL-1β, IL-2, IL-12, and IFN-γ significantly increased among the three groups (baseline < control < probiotics). This result demonstrated that probiotics helped to shift the anti-inflammatory state to a pro-inflammatory state. The correlation analysis outcome suggested that the relationship between the microbiota and the cytokines was not strain-dependent. The gut microbiota varied during the third trimester. The probiotics demonstrated immunomodulation effects that helped to switch over to a pro-inflammatory immune state in the third trimester, which was important for labor.

Aged garlic extract ameliorates fatty liver and insulin resistance and improves the gut microbiota profile in a mouse model of insulin resistance

Aged garlic extract (AGE) produced by the aging process has various beneficial pharmacological effects. In this study, the effects of AGE on fatty liver, insulin resistance and intestinal microbiota were compared between ddY-H mice, an insulin resistance mouse, and ddY-L mice, normal mice. Mice were fed an AGE-supplemented diet (4% w/w) for 7 weeks. The administration of AGE had no effect on the body weight and dietary intake of both types of mice. In the ddY-H mice, the serum levels of glucose and insulin were increased and glucose tolerance was impaired; however, the administration of AGE ameliorated these abnormal conditions. AGE did not have these effects in ddY-L mice. Triglyceride (TG) accumulation in the liver and fat absorption from the digestive tract were increased in the ddY-H mice; however, the administration of AGE reduced this increase. On the other hand, AGE exerted no such effects in the ddY-L mice. In addition, the gut microbiota has been shown to be closely associated with obesity, diabetes, dyslipidemia and non-alcoholic fatty liver disease in human and animal models. The bacterial composition of the gut microbiota in the feces of the ddY-H mice did not differ from that of the ddY-L mice at 5 weeks of age; however, it was altered in the mice at 9 and 12 weeks of age even when the mice were fed a standard diet. In the ddY-H mice, the relative presence of Lactobacillales was increased, while that of Bifidobacterium, Clostridium cluster XVIII and Prevotella was decreased. The alteration of the bacterial composition in the ddY-H mice was reversed by the administration of AGE; however, this effect of AGE was not observed in the ddY-L mice. On the whole, the findings of this study indicate that AGE improves abnormal fat accumulation and insulin resistance, and also alters the intestinal flora in ddY-H mice, suggesting the possibility that these effects of AGE may be related.

Defining Dysbiosis in Patients with Urolithiasis

The prevalence of urinary stone disease (USD) is rapidly rising. However, the factors driving this increase are unknown. Recent microbiome studies suggest that dysbiosis may in part contribute to the increasing prevalence. The objective of the current study was to determine the nature and location of dysbiosis associated with USD. We conducted microbiome analysis from the gastrointestinal and urinary tracts, along with a metabolomic analysis of the urinary metabolome, from subjects with an active episode of USD or no history of the disease. Higher rates of antibiotic use among USD patients along with integrated microbiome and metabolomic results support the hypothesis that USD is associated with an antibiotic-driven shift in the microbiome from one that protects against USD to one that promotes the disease. Specifically, our study implicates urinary tract Lactobacillus and Enterobacteriaceae in protective and pathogenic roles for USD, respectively, which conventional, culture-based methods of bacterial analysis from urine and kidney stones would not necessarily detect. Results suggest that antibiotics produce a long-term shift in the microbiome that may increase the risk for USD, with the urinary tract microbiome holding more relevance for USD than the gut microbiome.

Gut-microbiota-on-a-chip: an enabling field for physiological research

Overwhelming scientific evidence today confirms that the gut microbiota is a central player in human health. Knowledge about interactions between human gut microbiota and human health has evolved rapidly in the last decade, based on experimental work involving analysis of human fecal samples or animal models (mainly rodents). A more detailed and cost-effective description of this interplay is now being enabled by the use of in vitro systems (i.e., gut-microbiota-on-chip systems) that recapitulate key aspects of the interaction between microbiota and human cells. Here, we review recent examples of the design and use of pioneering on-chip platforms for the study of the cross-talk between representative members of human microbiota and human microtissues. In these systems, the combined use of state-of-the-art microfluidics, biomaterials, cell culture techniques, classical microbiology, and a touch of genetic expression profiling have converged for the development of gut-on-chip platforms capable of recreating key features of the interplay between human microbiota and host human tissues. We foresee that the integration of novel microfabrication techniques and stem cell technologies will further accelerate the development of more complex and physiologically relevant microbiota-on-chip platforms. In turn, this will foster the faster acquisition of knowledge regarding human microbiota and will enable important advances in the understanding of how to control or prevent disease.

Curcumin, Cardiometabolic Health and Dementia

Current research indicates curcumin [diferuloylmethane; a polyphenolic compound isolated from the rhizomes of the dietary spice turmeric (Curcuma longa)] exerts a beneficial effect on health which may be partly attributable to its anti-oxidative and anti-inflammatory properties. The aim of this review is to examine potential mechanisms of the actions of curcumin in both animal and human studies. Curcumin modulates relevant molecular target pathways to improve glucose and lipid metabolism, suppress inflammation, stimulate antioxidant enzymes, facilitate insulin signalling and reduce gut permeability. Curcumin also inhibits Aβ and tau accumulation in animal models and enhances mitochondria and synaptic function. In conclusion, in high-dose animal studies and in vitro, curcumin exerts a potential beneficial effect on cardiometabolic disease. However, human studies are relatively unconvincing. More intervention studies should be conducted with the new curcumin formulation with improved oral bioavailability.

Unhealthy gut, unhealthy brain: The role of the intestinal microbiota in neurodegenerative diseases

The number of bacterial cells living within the human body is approximately equal to, or greater than, the total number of human cells. This dynamic population of microorganisms, termed the human microbiota, resides mainly within the gastrointestinal tract. It is widely accepted that highly diverse and stable microbiota promote overall human health. Colonization of the gut with maladaptive and pathogenic microbiota, a state also known as dysbiosis, is associated with a variety of peripheral diseases ranging from type 2 diabetes mellitus to cardiovascular and inflammatory bowel disease. More recently, microbial dysbiosis has been associated with a number of brain pathologies, including autism spectrum disorder, Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS), suggesting a direct or indirect communication between intestinal bacteria and the central nervous system (CNS). In this review, we illustrate two pathways implicated in the crosstalk between gut microbiota and CNS involving 1) the vagus nerve and 2) transmission of signaling molecules through the circulatory system and across the blood-brain barrier (BBB). We summarize the available evidence of the specific changes in the intestinal microbiota, as well as microorganism-induced modifications to intestinal and BBB permeability, which have been linked to several neurodegenerative disorders including ALS, AD, and PD. Even though each of these diseases arises from unique pathogenetic mechanisms, all are characterized, at least in part, by chronic neuroinflammation. We provide an interpretation for the substantial evidence that healthy intestinal microbiota have the ability to positively regulate the neuroimmune responses in the CNS. Even though the evidence is mainly associative, it has been suggested that bacterial dysbiosis could contribute to an adverse neuroinflammatory state leading to increased risk of neurodegenerative diseases. Thus, developing strategies for regulating and maintaining healthy intestinal microbiota could be a valid approach for lowering individual risk and prevalence of neurodegenerative diseases.

Impact of Edible Cricket Consumption on Gut Microbiota in Healthy Adults, a Double-blind, Randomized Crossover Trial

Edible insects are often considered a nutritious, protein-rich, environmentally sustainable alternative to traditional livestock with growing popularity among North American consumers. While the nutrient composition of several insects is characterized, all potential health impacts have not been evaluated. In addition to high protein levels, crickets contain chitin and other fibers that may influence gut health. In this study, we evaluated the effects of consuming 25 grams/day whole cricket powder on gut microbiota composition, while assessing safety and tolerability. Twenty healthy adults participated in this six-week, double-blind, crossover dietary intervention. Participants were randomized into two study arms and consumed either cricket-containing or control breakfast foods for 14 days, followed by a washout period and assignment to the opposite treatment. Blood and stool samples were collected at baseline and after each treatment period to assess liver function and microbiota changes. Results demonstrate cricket consumption is tolerable and non-toxic at the studied dose. Cricket powder supported growth of the probiotic bacterium, Bifidobacterium animalis, which increased 5.7-fold. Cricket consumption was also associated with reduced plasma TNF-α. These data suggest that eating crickets may improve gut health and reduce systemic inflammation; however, more research is needed to understand these effects and underlying mechanisms.

Dynamics of Gut Microbiota Diversity During the Early Development of an Avian Host: Evidence From a Cross-Foster Experiment

Despite the increasing knowledge on the processes involved in the acquisition and development of the gut microbiota in model organisms, the factors influencing early microbiota successions in natural populations remain poorly understood. In particular, little is known on the role of the rearing environment in the establishment of the gut microbiota in wild birds. Here, we examined the influence of the nesting environment on the gut microbiota of Great tits (Parus major) by performing a partial cross-fostering experiment during the intermediate stage of nestling development. We found that the cloacal microbiota of great tit nestlings underwent substantial changes between 8 and 15 days of age, with a strong decrease in diversity, an increase in the relative abundance of Firmicutes and a shift in the functional features of the community. Second, the nesting environment significantly influenced community composition, with a divergence among separated true siblings and a convergence among foster siblings. Third, larger shifts in both microbiota diversity and composition correlated with lower nestling body condition. Our results shed new light on the dynamics of microbial diversity during the ontogeny of avian hosts, indicating that the nest environment continues to shape the gut microbiota during the later stages of nestling development and that the increase in gut diversity between hatching and adulthood may not be as linear as previously suspected. Lastly, the microbiota changes incurred during this period may have implications for nestling body condition which can lead to long-term consequences for host fitness.

Biomarkers for monitoring intestinal health in poultry: present status and future perspectives

Intestinal health is determined by host (immunity, mucosal barrier), nutritional, microbial and environmental factors. Deficiencies in intestinal health are associated with shifts in the composition of the intestinal microbiome (dysbiosis), leakage of the mucosal barrier and/or inflammation. Since the ban on growth promoting antimicrobials in animal feed, these dysbiosis-related problems have become a major issue, especially in intensive animal farming. The economical and animal welfare consequences are considerable. Consequently, there is a need for continuous monitoring of the intestinal health status, particularly in intensively reared animals, where the intestinal function is often pushed to the limit. In the current review, the recent advances in the field of intestinal health biomarkers, both in human and veterinary medicine are discussed, trying to identify present and future markers of intestinal health in poultry. The most promising new biomarkers will be stable molecules ending up in the feces and litter that can be quantified, preferably using rapid and simple pen-side tests. It is unlikely, however, that a single biomarker will be sufficient to follow up all aspects of intestinal health. Combinations of multiple biomarkers and/or metabarcoding, metagenomic, metatranscriptomic, metaproteomic and metabolomic approaches will be the way to go in the future. Candidate biomarkers currently are being investigated by many research groups, but the validation will be a major challenge, due to the complexity of intestinal health in the field.

Dysbiotic drift and biopsychosocial medicine: how the microbiome links personal, public and planetary health

The emerging concept of planetary health emphasizes that the health of human civilization is intricately connected to the health of natural systems within the Earth’s biosphere; here, we focus on the rapidly progressing microbiome science - the microbiota-mental health research in particular - as a way to illustrate the pathways by which exposure to biodiversity supports health. Microbiome science is illuminating the ways in which stress, socioeconomic disadvantage and social polices interact with lifestyle and behaviour to influence the micro and macro-level biodiversity that otherwise mediates health. Although the unfolding microbiome and mental health research is dominated by optimism in biomedical solutions (e.g. probiotics, prebiotics), we focus on the upstream psychosocial and ecological factors implicated in dysbiosis; we connect grand scale biodiversity in the external environment with differences in human-associated microbiota, and, by extension, differences in immune function and mental outlook. We argue that the success of planetary health as a new concept will be strengthened by a more sophisticated understanding of the ways in which individuals develop emotional connections to nature (nature relatedness) and the social policies and practices which facilitate or inhibit the pro-environmental values that otherwise support personal, public and planetary health.

Inside the guts of the city: Urban-induced alterations of the gut microbiota in a wild passerine

Urbanisation represents one of the most radical forms of terrestrial land use change and has been shown to lead to alterations in ecosystem functioning and community dynamics and changes in individual phenotypic traits. While the recent surge in microbiome studies has brought about a paradigm shift by which individuals cannot truly be considered independently of the bacterial communities they host, the role of gut microbiota in organismal response to human-induced environmental change is still scarcely studied. Here, we applied a metabarcoding approach to examine the impact of urbanisation on the gut microbiota of Passer domesticus. We found urbanisation to be associated to lower microbiota species diversity, modifications in taxonomic composition and community structure, and changes in functional composition. The strength of these relationships, however, depended on the spatial scale and season at which they were considered. Such spatio-temporal effect suggests that urbanisation may dampen the natural seasonal variation of the gut microbiota observed in more pristine habitats, potentially influencing the fitness of urban organisms. Our results hence shed light on a hitherto little considered perspective, i.e. that the negative effects of urbanisation on city-dwelling organisms may extend to their microbiomes, causing potential dysbioses.

The Problem of Curcumin and Its Bioavailability: Could Its Gastrointestinal Influence Contribute to Its Overall Health-Enhancing Effects?

Curcumin, from the spice turmeric, exhibits anti-inflammatory, antioxidant, anticancer, antiviral, and neurotrophic activity and therefore holds promise as a therapeutic agent to prevent and treat several disorders. However, a major barrier to curcumin's clinical efficacy is its poor bioavailability. Efforts have therefore been dedicated to developing curcumin formulations with greater bioavailability and systemic tissue distribution. However, it is proposed in this review that curcumin's potential as a therapeutic agent may not solely rely on its bioavailability, but rather its medicinal benefits may also arise from its positive influence on gastrointestinal health and function. In this review, in vitro, animal, and human studies investigating the effects of curcumin on intestinal microbiota, intestinal permeability, gut inflammation and oxidative stress, anaphylactic response, and bacterial, parasitic, and fungal infections are summarized. It is argued that positive changes in these areas can have wide-ranging influences on both intestinal and extraintestinal diseases, and therefore presents as a possible mechanism behind curcumin's therapeutic efficacy.

[Therapeutic modulation of intestinal microbiota in irritable bowel syndrome. From probiotics to fecal microbiota therapy]

BACKGROUND

An abnormal intestinal microbiota (dysbiosis) plays a central role in the pathogenesis of the irritable bowel syndrome.

METHOD

An overview of four current options for the treatment of irritable bowel syndrome, which are characterized by modulation of intestinal microbiota, is given.

RESULTS AND CONCLUSIONS

Probiotics have very different effects on the individual symptoms of the irritable bowel. The choice of the appropriate preparation should therefore be based on the clinical symptomatology. The antibiotic rifaximin is effective in selected patients. Some patients also benefit from the repetition of this therapy. A FODMAP-reduced diet has shown significant alleviation of irritable bowel symptoms in studies. The fecal microbiota therapy (FMT) is a promising treatment option. At present, however, there are no such placebo-controlled studies to assess the effectiveness of this method.

Preterm Birth Affects the Risk of Developing Immune-Mediated Diseases

Prematurity affects approximately 10% of all children, resulting in drastically altered antigen exposure due to premature confrontation with microbes, nutritional antigens, and other environmental factors. During the last trimester of pregnancy, the fetal immune system adapts to tolerate maternal and self-antigens, while also preparing for postnatal immune defense by acquiring passive immunity from the mother. Since the perinatal period is regarded as the most important “window of opportunity” for imprinting metabolism and immunity, preterm birth may have long-term consequences for the development of immune-mediated diseases. Intriguingly, preterm neonates appear to develop bronchial asthma more frequently, but atopic dermatitis less frequently in comparison to term neonates. The longitudinal study of preterm neonates could offer important insights into the process of imprinting for immune-mediated diseases. On the one hand, preterm birth may interrupt influences of the intrauterine environment on the fetus that increase or decrease the risk of later immune disease (e.g., maternal antibodies and placenta-derived factors), whereas on the other hand, it may lead to the premature exposure to protective or harmful extrauterine factors such as microbiota and nutritional antigen. Solving this puzzle may help unravel new preventive and therapeutic approaches for immune diseases.

The skin microbiome: impact of modern environments on skin ecology, barrier integrity, and systemic immune programming

Skin barrier structure and function is essential to human health. Hitherto unrecognized functions of epidermal keratinocytes show that the skin plays an important role in adapting whole-body physiology to changing environments, including the capacity to produce a wide variety of hormones, neurotransmitters and cytokine that can potentially influence whole-body states, and quite possibly, even emotions. Skin microbiota play an integral role in the maturation and homeostatic regulation of keratinocytes and host immune networks with systemic implications. As our primary interface with the external environment, the biodiversity of skin habitats is heavily influenced by the biodiversity of the ecosystems in which we reside. Thus, factors which alter the establishment and health of the skin microbiome have the potential to predispose to not only cutaneous disease, but also other inflammatory non-communicable diseases (NCDs). Indeed, disturbances of the stratum corneum have been noted in allergic diseases (eczema and food allergy), psoriasis, rosacea, acne vulgaris and with the skin aging process. The built environment, global biodiversity losses and declining nature relatedness are contributing to erosion of diversity at a micro-ecological level, including our own microbial habitats. This emphasises the importance of ecological perspectives in overcoming the factors that drive dysbiosis and the risk of inflammatory diseases across the life course.

Lactobacillus acidophilus/Bifidobacterium infantis probiotics are associated with increased growth of VLBWI among those exposed to antibiotics

We performed an observational study with very-low-birth weight infants (VLBWI) ≤33 weeks of gestation born in centers of the German Neonatal Network (GNN; (total n = 8534, n = 6229 received probiotics). The primary objectives of our study were (a) to assess the effect of Lactobacillus acidophilus/Bifidobacterium infantis probiotics on growth in VLBWI during primary stay in hospital and (b) to determine whether this effect is modified by antibiotic exposure. In linear regression models the administration of probiotics was independently associated with improved weight gain [g/d; effect size B = 0.62 (95% CI: 0.37-0.87), p < 0.001], and higher growth rates for body length [(mm/d; B = 0.06 (95% CI: 0.04-0.08), p < 0.001] and head circumference [mm/d; B = 0.03, 95% CI: 0.02-0.04, p < 0.001]. This effect was pronounced in infants with postnatal exposure to antibiotics; i.e. weight gain [g/d; B = 0.66 (95% CI: 0.32-1), p < 0.001], growth rate body length [(mm/d; B = 0.09 (95% CI: 0.06-0.12), p < 0.001] and head circumference [mm/d; B = 0.04, 95% CI: 0.02-0.06, p < 0.001]. In the small subgroup that was available for analysis at 5-year-follow-up (with probiotics: n = 120 vs. without probiotics: n = 54) we noted a sustained effect of probiotics in infants who received postnatal antibiotics. Probiotics may improve growth in antibiotic-treated infants which needs to be confirmed in randomized-controlled trials.