Impact of diet and the bacterial microbiome on the mucous barrier and immune disorders

The beneficial effects of Akkermansia muciniphila and its derivatives on pulmonary fibrosis

Pulmonary fibrosis (PF) is a progressive and debilitating respiratory condition characterized by excessive deposition of extracellular matrix proteins and scarring within the lung parenchyma. Despite extensive research, the pathogenesis of PF remains incompletely understood, and effective therapeutic options are limited. Emerging evidence suggests a potential link between gut microbiota dysbiosis and the development of PF, highlighting the gut-lung axis as a promising therapeutic target. Akkermansia muciniphila (A. muciniphila), a mucin-degrading bacterium residing in the gut mucosal layer, has garnered considerable interest due to its immunomodulatory and anti-inflammatory properties. This study investigates the therapeutic potential of live and pasteurized A. muciniphila, as well as its extracellular vesicles (EVs), in mitigating inflammation and fibrosis in a murine model of carbon tetrachloride (CCl4)-induced PF exacerbated by a high-fat diet (HFD). Male C57BL/6 mice were divided into groups receiving either a normal diet or an HFD, with or without CCl4 administration. The mice were then treated with live or pasteurized A. muciniphila, or its EVs. Lung tissue was analyzed for the expression of inflammatory markers and fibrosis markers using real-time PCR and ELISA. Administration of live and pasteurized A. muciniphila, as well as its EVs, significantly downregulated the expression of inflammatory and fibrosis markers in the lung tissue of CCl4-induced PF mice. Furthermore, these treatments ameliorated the increased production of IL-6 and reduced IL-10 levels observed in the HFD and CCl4-treated groups. These findings suggest that A. muciniphila and its derivatives exert protective effects against pulmonary inflammation and fibrosis, potentially through modulation of the gut-lung axis. The study highlights the therapeutic potential of A. muciniphila and its derivatives as novel interventions for the management of PF, warranting further preclinical and clinical investigations.

The interaction of innate immune and adaptive immune system

The innate immune system serves as the body's first line of defense, utilizing pattern recognition receptors like Toll-like receptors to detect pathogens and initiate rapid response mechanisms. Following this initial response, adaptive immunity provides highly specific and sustained killing of pathogens via B cells, T cells, and antibodies. Traditionally, it has been assumed that innate immunity activates adaptive immunity; however, recent studies have revealed more complex interactions. This review provides a detailed dissection of the composition and function of the innate and adaptive immune systems, emphasizing their synergistic roles in physiological and pathological contexts, providing new insights into the link between these two forms of immunity. Precise regulation of both immune systems at the same time is more beneficial in the fight against immune-related diseases, for example, the cGAS-STING pathway has been found to play an important role in infections and cancers. In addition, this paper summarizes the challenges and future directions in the field of immunity, including the latest single-cell sequencing technologies, CAR-T cell therapy, and immune checkpoint inhibitors. By summarizing these developments, this review aims to enhance our understanding of the complexity interactions between innate and adaptive immunity and provides new perspectives in understanding the immune system.

The Current Molecular and Cellular Landscape of Chronic Obstructive Pulmonary Disease (COPD): A Review of Therapies and Efforts towards Personalized Treatment

Chronic obstructive pulmonary disease (COPD) ranks as the third leading cause of global illness and mortality. It is commonly triggered by exposure to respiratory irritants like cigarette smoke or biofuel pollutants. This multifaceted condition manifests through an array of symptoms and lung irregularities, characterized by chronic inflammation and reduced lung function. Present therapies primarily rely on maintenance medications to alleviate symptoms, but fall short in impeding disease advancement. COPD's diverse nature, influenced by various phenotypes, complicates diagnosis, necessitating precise molecular characterization. Omics-driven methodologies, including biomarker identification and therapeutic target exploration, offer a promising avenue for addressing COPD's complexity. This analysis underscores the critical necessity of improving molecular profiling to deepen our comprehension of COPD and identify potential therapeutic targets. Moreover, it advocates for tailoring treatment strategies to individual phenotypes. Through comprehensive exploration-based molecular characterization and the adoption of personalized methodologies, innovative treatments may emerge that are capable of altering the trajectory of COPD, instilling optimism for efficacious disease-modifying interventions.

Sex-specific alterations in the gut and lung microbiome of allergen-induced mice

Introduction

Recent evidence has demonstrated that the microbiome is a driver of the underlying pathophysiological mechanisms of respiratory disease. Studies have indicated that bacterial metabolites produced in the gut and lung can impact lung inflammation and immune cell activity, affecting disease pathology. Despite asthma being a disease with marked sex differences, experimental work linking microbiomes and asthma has not considered the sex variable.

Methods

To test the hypothesis that the lung and gut microbial composition impacts allergic lung inflammation in a sex-specific manner, we evaluated lung and gut microbiome alterations in a mouse model of allergic inflammation and assessed their association with lung function and inflammation phenotypes. For this, we exposed male and female adult C57BL/6J mice intranasally to 25 µg of a house dust mite extract mix (HDM) daily, or phosphate-buffered saline (PBS) as control, for 5 weeks (n = 4-6/group). DNA from fecal pellets collected before and after the 5-week treatment, and from lung tissue collected at endpoint, was extracted using the ZymoBIOMICS®-96 MagBead DNA Kit and analyzed to determine the 16S microbiome via Targeted Metagenomic Sequencing.

Results

The HDM treatment induced a sex-specific allergic inflammation phenotype with significantly higher neutrophilia, lymphocytosis, inflammatory gene expression, and histopathological changes in females than males following exposure to HDM, but higher airway hyperresponsiveness (AHR) in males than females. In addition, sex-specific lung gene expression and associated pathways were identified HDM mix after challenge. These changes corresponded to sex-specific alterations in the gut microbiome, where the Firmicutes to Bacteroidetes ratio (F:B) was significantly reduced in fecal samples from only male mice after HDM challenge, and alpha diversity was increased in males, but decreased in females, after 5-weeks of HDM treatment.

Discussion

Overall, our findings indicate that intranasal allergen challenge triggers sex-specific changes in both gut and lung microbiomes, and induces sex-specific lung inflammation, AHR, and lung inflammatory gene expression pathways, suggesting a contribution of the lung-gut axis in allergic airway disease.

Lifestyle Changes and Industrialization in the Development of Allergic Diseases

PURPOSE OF REVIEW

Modernization and Westernization in industrialized and developing nations is associated with a substantial increase in chronic noncommunicable diseases. This transformation has far-reaching effects on lifestyles, impacting areas such as economics, politics, social life, and culture, all of which, in turn, have diverse influences on public health. Loss of contact with nature, alternations in the microbiota, processed food consumption, exposure to environmental pollutants including chemicals, increased stress and decreased physical activity jointly result in increases in the frequency of inflammatory disorders including allergies and many autoimmune and neuropsychiatric diseases. This review aims to investigate the relationship between Western lifestyle and inflammatory disorders.

RECENT FINDINGS

Several hypotheses have been put forth trying to explain the observed increases in these diseases, such as 'Hygiene Hypothesis', 'Old Friends', and 'Biodiversity and Dysbiosis'. The recently introduced 'Epithelial Barrier Theory' incorporates these former hypotheses and suggests that toxic substances in cleaning agents, laundry and dishwasher detergents, shampoos, toothpastes, as well as microplastic, packaged food and air pollution damage the epithelium of our skin, lungs and gastrointestinal system. Epithelial barrier disruption leads to decreased biodiversity of the microbiome and the development of opportunistic pathogen colonization, which upon interaction with the immune system, initiates local and systemic inflammation. Gaining a deeper comprehension of the interplay between the environment, microbiome and the immune system provides the data to assist with legally regulating the usage of toxic substances, to enable nontoxic alternatives and to mitigate these environmental challenges essential for fostering a harmonious and healthy global environment.

The impact of high-salt diet on asthma in humans and mice: Effect on specific T-cell signatures and microbiome

BACKGROUND

The rise in asthma has been linked to different environmental and lifestyle factors including dietary habits. Whether dietary salt contributes to asthma incidence, remains controversial. We aimed to investigate the impact of higher salt intake on asthma incidence in humans and to evaluate underlying mechanisms using mouse models.

METHODS

Epidemiological research was conducted using the UK Biobank Resource. Data were obtained from 42,976 participants with a history of allergies. 24-h sodium excretion was estimated from spot urine, and its association with asthma incidence was assessed by Cox regression, adjusting for relevant covariates. For mechanistic studies, a mouse model of mite-induced allergic airway inflammation (AAI) fed with high-salt diet (HSD) or normal-salt chow was used to characterize disease development. The microbiome of lung and feces (as proxy for gut) was analyzed via 16S rRNA gene based metabarcoding approach.

RESULTS

In humans, urinary sodium excretion was directly associated with asthma incidence among females but not among males. HSD-fed female mice displayed an aggravated AAI characterized by increased levels of total IgE, a TH2-TH17-biased inflammatory cell infiltration accompanied by upregulation of osmosensitive stress genes. HSD induced distinct changes in serum short chain fatty acids and in both gut and lung microbiome, with a lower Bacteroidetes to Firmicutes ratio and decreased Lactobacillus relative abundance in the gut, and enriched members of Gammaproteobacteria in the lung.

CONCLUSIONS

High dietary salt consumption correlates with asthma incidence in female adults with a history of allergies. Female mice revealed HSD-induced T-cell lung profiles accompanied by alterations of gut and lung microbiome.

Targeting Nrf2 by bioactive peptides alleviate inflammation: expanding the role of gut microbiota and metabolites

Inflammation is a complex process that usually refers to the general response of the body to the harmful stimuli of various pathogens, tissue damage, or exogenous pollutants. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a transcription factor that regulates cellular defense against oxidative damage and toxicity by expressing genes related to oxidative stress response and drug detoxification. In addition to its antioxidant properties, Nrf2 is involved in many other important physiological processes, including inflammation and metabolism. Nrf2 can bind the promoters of antioxidant genes and upregulates their expressions, which alleviate oxidation-induced inflammation. Nrf2 has been shown to upregulate heme oxygenase-1 expression, which promotes NF-κB activation and is closely related with inflammation. Nrf2, as a key factor in antioxidant response, is closely related to the expressions of pro-inflammatory factors, NF-κB pathway and cell metabolism. Bioactive peptides come from a wide range of sources and have many biological functions. Increasing evidence indicates that bioactive peptides have potential anti-inflammatory activities. This article summarized the sources, absorption and utilization of bioactive peptides and their role in alleviating inflammation via Nrf2 pathway. Bioactive peptides can also regulate gut microbiota and alter metabolites, which regulates the Nrf2 pathway through novel pathway and supplement the anti-inflammatory mechanisms of bioactive peptides. This review provides a reference for further study on the anti-inflammatory effect of bioactive peptides and the development and utilization of functional foods.

Relationship between dietary live microbe intake and the prevalence of COPD in adults: a cross-sectional study of NHANES 2013-2018

OBJECTIVE

To explore the potential association between dietary live microbes and the prevalence of Chronic Obstructive Pulmonary Diseases (COPD).

METHODS

In this cross-sectional study, data of 9791 participants aged 20 years or older in this study were collected from the National Health and Nutrition Examination Survey (NHANES) between 2013 and 2018. Participants in this study were classified into three groups according to the Sanders' dietary live microbe classification system: low, medium, and high dietary live microbe groups. COPD was defined by a combination of self-reported physician diagnoses and standardized medical status questionnaires. Logistic regression and subgroup analysis were used to assess whether dietary live microbes were associated with the risk of COPD.

RESULTS

Through full adjustment for confounders, participants in the high dietary live microbe group had a low prevalence of COPD in contrast to those in low dietary live microbe group (OR: 0.614, 95% CI: 0.474-0.795, and p < 0.001), but no significant association with COPD was detected in the medium and the low dietary live microbe groups. This inverse relationship between dietary live microbe intake and COPD prevalence was more inclined to occur in smokers, females, participants aged from 40 to 59 years old and non-obese participants.

CONCLUSION

A high dietary live microbe intake was associated with a low prevalence of COPD, and this negative correlation was detected especially in smokers, females, participants aged from 40 to 59 years old and non-obese participants.

Faecal microbial transfer and complex carbohydrates mediate protection against COPD

OBJECTIVE

Chronic obstructive pulmonary disease (COPD) is a major cause of global illness and death, most commonly caused by cigarette smoke. The mechanisms of pathogenesis remain poorly understood, limiting the development of effective therapies. The gastrointestinal microbiome has been implicated in chronic lung diseases via the gut-lung axis, but its role is unclear.

DESIGN

Using an in vivo mouse model of cigarette smoke (CS)-induced COPD and faecal microbial transfer (FMT), we characterised the faecal microbiota using metagenomics, proteomics and metabolomics. Findings were correlated with airway and systemic inflammation, lung and gut histopathology and lung function. Complex carbohydrates were assessed in mice using a high resistant starch diet, and in 16 patients with COPD using a randomised, double-blind, placebo-controlled pilot study of inulin supplementation.

RESULTS

FMT alleviated hallmark features of COPD (inflammation, alveolar destruction, impaired lung function), gastrointestinal pathology and systemic immune changes. Protective effects were additive to smoking cessation, and transfer of CS-associated microbiota after antibiotic-induced microbiome depletion was sufficient to increase lung inflammation while suppressing colonic immunity in the absence of CS exposure. Disease features correlated with the relative abundance of Muribaculaceae, Desulfovibrionaceae and Lachnospiraceae family members. Proteomics and metabolomics identified downregulation of glucose and starch metabolism in CS-associated microbiota, and supplementation of mice or human patients with complex carbohydrates improved disease outcomes.

CONCLUSION

The gut microbiome contributes to COPD pathogenesis and can be targeted therapeutically.

The Role of Mitochondrial Quality Control in Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity, mortality, and health care use worldwide with heterogeneous pathogenesis. Mitochondria, the powerhouses of cells responsible for oxidative phosphorylation and energy production, play essential roles in intracellular material metabolism, natural immunity, and cell death regulation. Therefore, it is crucial to address the urgent need for fine-tuning the regulation of mitochondrial quality to combat COPD effectively. Mitochondrial quality control (MQC) mainly refers to the selective removal of damaged or aging mitochondria and the generation of new mitochondria, which involves mitochondrial biogenesis, mitochondrial dynamics, mitophagy, etc. Mounting evidence suggests that mitochondrial dysfunction is a crucial contributor to the development and progression of COPD. This article mainly reviews the effects of MQC on COPD as well as their specific regulatory mechanisms. Finally, the therapeutic approaches of COPD via MQC are also illustrated.

Reappraisal of Adipose Tissue Inflammation in Obesity

Chronic low-grade inflammation is a central component in the pathogenesis of obesity-related expansion of adipose tissue and complications in other metabolic tissues. Five different signaling pathways are defined as dominant determinants of adipose tissue inflammation: These are increased circulating endotoxin due to dysregulation in the microbiota-gut-brain axis, systemic oxidative stress, macrophage accumulation, and adipocyte death. Finally, the nucleotide-binding and oligomerization domain (NOD) leucine-rich repeat family pyrin domain-containing 3 (NLRP3) inflammasome pathway is noted to be a key regulator of metabolic inflammation. The NLRP3 inflammasome and associated metabolic inflammation play an important role in the relationships among fatty acids and obesity. Several highly active molecules, including primarily leptin, resistin, adiponectin, visfatin, and classical cytokines, are abundantly released from adipocytes. The most important cytokines that are released by inflammatory cells infiltrating obese adipose tissue are tumor necrosis factor-alpha (TNF-α), interleukin 6 (IL-6), monocyte chemoattractant protein 1 (MCP-1) (CCL-2), and IL-1. All these molecules mentioned above act on immune cells, causing local and then general inflammation. Three metabolic pathways are noteworthy in the development of adipose tissue inflammation: toll-like receptor 4 (TLR4)/phosphatidylinositol-3'-kinase (PI3K)/Protein kinase B (Akt) signaling pathway, endoplasmic reticulum (ER) stress-derived unfolded protein response (UPR), and inhibitor of nuclear factor kappa-B kinase beta (IKKβ)-nuclear factor kappa B (NF-κB) pathway. In fact, adipose tissue inflammation is an adaptive response that contributes to a visceral depot barrier that effectively filters gut-derived endotoxin. Excessive fatty acid release worsens adipose tissue inflammation and contributes to insulin resistance. However, suppression of adipose inflammation in obesity with anti-inflammatory drugs is not a rational solution and paradoxically promotes insulin resistance, despite beneficial effects on weight gain. Inflammatory pathways in adipocytes are indeed indispensable for maintaining systemic insulin sensitivity. Cannabinoid type 1 receptor (CB1R) is important in obesity-induced pro-inflammatory response; however, blockade of CB1R, contrary to anti-inflammatory drugs, breaks the links between insulin resistance and adipose tissue inflammation. Obesity, however, could be decreased by improving leptin signaling, white adipose tissue browning, gut microbiota interactions, and alleviating inflammation. Furthermore, capsaicin synthesized by chilies is thought to be a new and promising therapeutic option in obesity, as it prevents metabolic endotoxemia and systemic chronic low-grade inflammation caused by high-fat diet.

Gut microbial metabolic signatures in diabetes mellitus and potential preventive and therapeutic applications

Diabetes mellitus can be subdivided into several categories based on origin and clinical characteristics. The most common forms of diabetes are type 1 (T1D), type 2 diabetes (T2D) and gestational diabetes mellitus (GDM). T1D and T2D are chronic diseases affecting around 537 million adults worldwide and it is projected that these numbers will increase by 12% over the next two decades, while GDM affects up to 30% of women during pregnancy, depending on diagnosis methods. These forms of diabetes have varied origins: T1D is an autoimmune disease, while T2D is commonly associated with, but not limited to, certain lifestyle patterns and GDM can result of a combination of genetic predisposition and pregnancy factors. Despite some pathogenic differences among these forms of diabetes, there are some common markers associated with their development. For instance, gut barrier impairment and inflammation associated with an unbalanced gut microbiota and their metabolites may be common factors in diabetes development and progression. Here, we summarize the microbial signatures that have been linked to diabetes, how they are connected to diet and, ultimately, the impact on metabolite profiles resulting from host-gut microbiota-diet interactions. Additionally, we summarize recent advances relating to promising preventive and therapeutic interventions focusing on the targeted modulation of the gut microbiota to alleviate T1D, T2D and GDM.

Epithelial Barrier Theory: The Role of Exposome, Microbiome, and Barrier Function in Allergic Diseases

Allergic diseases are a major public health problem with increasing prevalence. These immune-mediated diseases are characterized by defective epithelial barriers, which are explained by the epithelial barrier theory and continuously emerging evidence. Environmental exposures (exposome) including global warming, changes and loss of biodiversity, pollution, pathogens, allergens and mites, laundry and dishwasher detergents, surfactants, shampoos, body cleaners and household cleaners, microplastics, nanoparticles, toothpaste, enzymes and emulsifiers in processed foods, and dietary habits are responsible for the mucosal and skin barrier disruption. Exposure to barrier-damaging agents causes epithelial cell injury and barrier damage, colonization of opportunistic pathogens, loss of commensal bacteria, decreased microbiota diversity, bacterial translocation, allergic sensitization, and inflammation in the periepithelial area. Here, we review scientific evidence on the environmental components that impact epithelial barriers and microbiome composition and their influence on asthma and allergic diseases. We also discuss the historical overview of allergic diseases and the evolution of the hygiene hypothesis with theoretical evidence.

The epithelial barrier: The gateway to allergic, autoimmune, and metabolic diseases and chronic neuropsychiatric conditions

Since the 1960 s, our health has been compromised by exposure to over 350,000 newly introduced toxic substances, contributing to the current pandemic in allergic, autoimmune and metabolic diseases. The "Epithelial Barrier Theory" postulates that these diseases are exacerbated by persistent periepithelial inflammation (epithelitis) triggered by exposure to a wide range of epithelial barrier-damaging substances as well as genetic susceptibility. The epithelial barrier serves as the body's primary physical, chemical, and immunological barrier against external stimuli. A leaky epithelial barrier facilitates the translocation of the microbiome from the surface of the afflicted tissues to interepithelial and even deeper subepithelial locations. In turn, opportunistic bacterial colonization, microbiota dysbiosis, local inflammation and impaired tissue regeneration and remodelling follow. Migration of inflammatory cells to susceptible tissues contributes to damage and inflammation, initiating and aggravating many chronic inflammatory diseases. The objective of this review is to highlight and evaluate recent studies on epithelial physiology and its role in the pathogenesis of chronic diseases in light of the epithelial barrier theory.

Intestinal factors promoting the development of RORγt+ cells and oral tolerance

The gastrointestinal tract has to harmonize the two seemingly opposite functions of fulfilling nutritional needs and avoiding the entry of pathogens, toxins and agents that can cause physical damage. This balance requires a constant adjustment of absorptive and defending functions by sensing environmental changes or noxious substances and initiating adaptive or protective mechanisms against them through a complex network of receptors integrated with the central nervous system that communicate with cells of the innate and adaptive immune system. Effective homeostatic processes at barrier sites take the responsibility for oral tolerance, which protects from adverse reactions to food that cause allergic diseases. During a very specific time interval in early life, the establishment of a stable microbiota in the large intestine is sufficient to prevent pathological events in adulthood towards a much larger bacterial community and provide tolerance towards diverse food antigens encountered later in life. The beneficial effects of the microbiome are mainly exerted by innate and adaptive cells that express the transcription factor RORγt, in whose generation, mediated by different bacterial metabolites, retinoic acid signalling plays a predominant role. In addition, recent investigations indicate that food antigens also contribute, analogously to microbial-derived signals, to educating innate immune cells and instructing the development and function of RORγt+ cells in the small intestine, complementing and expanding the tolerogenic effect of the microbiome in the colon. This review addresses the mechanisms through which microbiota-produced metabolites and dietary antigens maintain intestinal homeostasis, highlighting the complementarity and redundancy between their functions.

Defects in microvillus crosslinking sensitize to colitis and inflammatory bowel disease

Intestinal epithelial cells are covered by the brush border, which consists of densely packed microvilli. The Intermicrovillar Adhesion Complex (IMAC) links the microvilli and is required for proper brush border organization. Whether microvillus crosslinking is involved in the intestinal barrier function or colitis is currently unknown. We investigate the role of microvillus crosslinking in colitis in mice with deletion of the IMAC component CDHR5. Electron microscopy shows pronounced brush border defects in CDHR5-deficient mice. The defects result in severe mucosal damage after exposure to the colitis-inducing agent DSS. DSS increases the permeability of the mucus layer and brings bacteria in direct contact with the disorganized brush border of CDHR5-deficient mice. This correlates with bacterial invasion into the epithelial cell layer which precedes epithelial apoptosis and inflammation. Single-cell RNA sequencing data of patients with ulcerative colitis reveals downregulation of CDHR5 in enterocytes of diseased areas. Our results provide experimental evidence that a combination of microvillus crosslinking defects with increased permeability of the mucus layer sensitizes to inflammatory bowel disease.

Dairy product consumption and lung cancer risk: A prospective analysis

BACKGROUND & AIM

Current evidence on prospective associations between dairy product, dairy fat and lactose intakes and lung cancer risk is limited and inconsistent. We conducted a prospective analysis of associations of lung cancer risk with dairy product intakes in the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial (PLCO) cohort.

METHODS

Pre-diagnostic dairy product intake was assessed through a validated Diet History Questionnaire. All incident lung cancer cases were pathologically verified. Multivariable Cox regression was used to calculate hazard ratios (HR) and 95% confidence intervals (CI) for associations of lung cancer risk with intakes of total, full-fat, low-fat dairy, fermented or non-fermented dairy products; milk fat content preference; and intakes of total and saturated fats and lactose from dairy products.

RESULTS

Among 101,709 adults (mean age of 65.5 years), a total of 1583 lung cancer cases were identified during 1,167,239 person-years of follow up. Mean total dairy product intake was 156 g/1000 kilocalories (kcal), including 20 g/1000 kcal from fermented dairy products. Total dairy intake was not associated with lung cancer risk (HR [95% CI] = 1.03 [0.89-1.18]) comparing the highest quartile with the lowest. Fermented dairy intake was inversely associated with lung cancer risk (0.85 [0.72-0.99]). In contrast, there were no statistically significant associations with low-fat, full-fat or non-fermented dairy product intakes. The preference of whole milk when consuming milk as beverage was associated with a higher risk of lung cancer than the preference of <0.5% fat milk (1.24 [1.03-1.49]). Total fat, saturated fat and lactose intakes from dairy products each were not associated with lung cancer risk.

CONCLUSIONS

Our results suggest an inverse association of lung cancer risk with fermented dairy intake and a positive association with the whole milk preference in a US population. Future studies exploring underlying molecular mechanisms are warranted.

Intratumor microbiota: Occult participants in the microenvironment of multiple myeloma

More recently, microbiota was detected in several tumorous tissues including multiple myeloma (MM), but the roles of which is still under-studied as paucity of research on tumor biology. Moreover, we also detected the presence of microbiota in the bone marrow of patients with MM by 2bRAD-M sequencing technology, which is an incurable hematological malignancy characterized by accumulation of abnormal plasma cells in the bone marrow. However, the roles of intratumor microbiota in tumor disease remains poorly understood. In this review, we critically reviewed recent literature about microbiota in the tumorigenesis and progression of MM. Importantly, we proposed that the emergence of microbiota in the microenvironment of multiple myeloma may be attributed to microbial dysbiosis and impaired intestinal barrier, due to the increased prevalence of MM in patients with obesity and diabetes, of which the characteristic phenotype is gut microbial dysbiosis and impaired intestinal barrier. When the intestinal barrier is damaged, dysbiotic microbiota and their metabolites, as well as dysregulated immune cells, may participate in the reshaping of the local immune microenvironment, and play pivotal roles in the tumorigenesis and development of multiple myeloma, probably by migrating to the bone marrow microenvironment from intestine. We also discuss the emerging microbiological manipulation strategies to improve long-term outcomes of MM, as well as the prospective of the state-of-the-art techniques to advance our knowledge about the biological implication in the microbiome in MM.

Potential probiotic lactobacilli strains isolated from artisanal Mexican Cocido cheese: evidence-based biosafety and probiotic action-related traits on in vitro tests

The biosafety of four potentially probiotic lactobacilli strains, isolated from artisanal Mexican Cocido cheese, was assessed through in vitro tests aimed to determine (1) the antibiotic susceptibility profile by broth microdilution, (2) the transferability of antibiotic resistance determinants by filter-mating, and (3) the phenotypic and genotypic stability during serial batch sub-culture (100-day period) by evaluating physiological and probiotic features and RAPD-PCR fingerprinting. Lactobacilli strains exhibited multidrug-resistance; however, resistance determinants were not transferred in the filter-mating assay. Significant (p < 0.05) differences were observed in bacterial morphology and some functional and technological properties when strains were serially sub-cultured over 50 generations (G50), compared to the initial cultures (G0). Conversely, the strains did not show mucinolytic and hemolytic activities either at G0 or after 100 generations (G100). Genetic polymorphism and genomic template instability on selected strains were detected, which suggest possible evolutionary arrangements that may occur when these bacteria are largely cultured. Our findings suggest that the assessed strains did not raise in vitro biosafety concerns; however, complementary studies are still needed to establish the safe potential applications in humans and animals.

Plectranthus amboinicus and rosemary (Rosmarinus officinalis L.) essential oils effects on performance, antioxidant activity, intestinal health, immune response, and plasma biochemistry in broiler chickens

This work aimed to assess the effects of Plectranthus amboinicus essential oil (PAE) and rosemary (Rosmarinus officinalis L.) essential oil (ROE) as feed additives on performance, antioxidant activity, intestinal microbiota, intestinal morphology, immune response, and plasma biochemistry using 320 unsexed 1-day-old Ross 308 broiler chickens. The chickens were assigned randomly into four treatments containing eight replicates with 10 chickens each. Treatment diets included a basal diet as a control group, 100 mg/kg PAE, 200 mg/kg PAE, and 100 mg/kg ROE. ROE affected the growth performance in the starter phase by improving (p = .01) the feed conversion ratio (FCR) compared with the control diet. Glutathione peroxidase (GPx) and superoxide dismutase (SOD) activity in the plasma were elevated (p < .0001) by both feed additives. Supplementation of additives could increase (p < .006) total antioxidant capacity (TAC). Furthermore, malondialdehyde (MDA) values in the breast (p < .0001) and thigh (p < .001) for all supplemented diets were less than the control group. The essential oils (EOs) reduced (p < .005) coliform counts in the ileum and increased (p = .029) lactic acid bacteria counts. In addition, villus height (VH) and crypt depth (CD) increased, whereas the density of goblet cells decreased in the small intestine when feed additives were included. Also, the antibody titers against sheep red blood cells (SRBC) and Newcastle disease virus (NDV) were increased (p < .0001) by EOs. Plasma total protein (p = .04) and globulin (p = .02) were increased, and cholesterol was reduced (p = .002) by supplemented diets. Our study revealed that PAE could effectively improve the antioxidant activity, intestinal microbiota population, intestinal morphology, immune response, and plasma biochemistry parameters in broiler chickens.

Inflammation, Autoinflammation and Autoimmunity in Inflammatory Bowel Diseases

In this review, the role of innate and adaptive immunity in the pathogenesis of inflammatory bowel diseases (IBD) is reported. In IBD, an altered innate immunity is often found, with increased Th17 and decreased Treg cells infiltrating the intestinal mucosa. An associated increase in inflammatory cytokines, such as IL-1 and TNF-α, and a decrease in anti-inflammatory cytokines, such as IL-10, concur in favoring the persistent inflammation of the gut mucosa. Autoinflammation is highlighted with insights in the role of inflammasomes, which activation by exogenous or endogenous triggers might be favored by mutations of NOD and NLRP proteins. Autoimmunity mechanisms also take place in IBD pathogenesis and in this context of a persistent immune stimulation by bacterial antigens and antigens derived from intestinal cells degradation, the adaptive immune response takes place and results in antibodies and autoantibodies production, a frequent finding in these diseases. Inflammation, autoinflammation and autoimmunity concur in altering the mucus layer and enhancing intestinal permeability, which sustains the vicious cycle of further mucosal inflammation.

Emerging epigenetic dynamics in gut-microglia brain axis: experimental and clinical implications for accelerated brain aging in schizophrenia

Brain aging, which involves a progressive loss of neuronal functions, has been reported to be premature in probands affected by schizophrenia (SCZ). Evidence shows that SCZ and accelerated aging are linked to changes in epigenetic clocks. Recent cross-sectional magnetic resonance imaging analyses have uncovered reduced brain reserves and connectivity in patients with SCZ compared to typically aging individuals. These data may indicate early abnormalities of neuronal function following cyto-architectural alterations in SCZ. The current mechanistic knowledge on brain aging, epigenetic changes, and their neuropsychiatric disease association remains incomplete. With this review, we explore and summarize evidence that the dynamics of gut-resident bacteria can modulate molecular brain function and contribute to age-related neurodegenerative disorders. It is known that environmental factors such as mode of birth, dietary habits, stress, pollution, and infections can modulate the microbiota system to regulate intrinsic neuronal activity and brain reserves through the vagus nerve and enteric nervous system. Microbiota-derived molecules can trigger continuous activation of the microglial sensome, groups of receptors and proteins that permit microglia to remodel the brain neurochemistry based on complex environmental activities. This remodeling causes aberrant brain plasticity as early as fetal developmental stages, and after the onset of first-episode psychosis. In the central nervous system, microglia, the resident immune surveillance cells, are involved in neurogenesis, phagocytosis of synapses and neurological dysfunction. Here, we review recent emerging experimental and clinical evidence regarding the gut-brain microglia axis involvement in SCZ pathology and etiology, the hypothesis of brain reserve and accelerated aging induced by dietary habits, stress, pollution, infections, and other factors. We also include in our review the possibilities and consequences of gut dysbiosis activities on microglial function and dysfunction, together with the effects of antipsychotics on the gut microbiome: therapeutic and adverse effects, role of fecal microbiota transplant and psychobiotics on microglial sensomes, brain reserves and SCZ-derived accelerated aging. We end the review with suggestions that may be applicable to the clinical setting. For example, we propose that psychobiotics might contribute to antipsychotic-induced therapeutic benefits or adverse effects, as well as reduce the aging process through the gut-brain microglia axis. Overall, we hope that this review will help increase the understanding of SCZ pathogenesis as related to chronobiology and the gut microbiome, as well as reveal new concepts that will serve as novel treatment targets for SCZ.

Ablation of CD226 on CD4+ T cells modulates asthma progress associated with altered IL-10 response and gut microbiota

To investigate the role of the costimulatory molecule CD226 in asthma pathogenesis, we produced a CD4⁺ T-cell-specific CD226 knockout mice model (Cd226^ΔCD4) and induced airway allergic inflammation by administering ovalbumin (OVA). Our results revealed alleviated lung inflammation, decreased levels of OVA-specific IgE, and increased levels of IL-10 in the serum of Cd226^ΔCD4 mice (P < 0.05). Moreover, IL-10 levels in CD4⁺ T cells were significantly elevated in the mediastinal lymph node, spleen, and Peyer's patches in the Cd226^ΔCD4 mice compared with those in controls (P < 0.05 to P < 0.01). Notably, there was a significantly higher IL-10 mRNA levels in the large intestine of the mice (P < 0.05). The protective effect of CD226 deficiency is also associated with the accumulation of gut TCRγδ⁺ intraepithelial lymphocytes and reversion of the gut microbiome dysbiosis. The Bacteroidetes-to-Firmicutes ratio and the abundance of Akkermansia increased in the absence of CD226 after OVA treatment. Our data reveal the synchronous changes in the lung and intestine in OVA-treated CD226-knockout mice, supporting the gut-lung axis concept and providing evidence for novel therapeutic approaches for asthma.

Capsazepine-Induced Altered Colonic Mucosal Health Limits Isomalto-oligosaccharide Action in High-Fat Diet-Fed C57BL/6J Mice

The present study sought to understand the effects of a combination of altered colonic mucosal health (intrarectal capsazepine administration) and high-fat diet (HFD) administration in mice. Furthermore, we also studied whether this combination prevents protective actions of dietary prebiotic, isomaltooligosaccharides. We studied the alterations in intestinal permeability, histological and transcriptional changes, short-chain fatty acid (SCFA) concentrations, and gut microbial abundance. Capsazepine (CPZ) was administered rectally twice a day along with HFD feeding. Following confirmation of CPZ action (loss of TRPA1 and TRPV1-associated nocifensive behavior), the intrarectal dose of CPZ was reduced to once in 2 days up to 8 weeks. Simultaneous intrarectal administration of CPZ exacerbated the HFD (8 weeks feeding)-induced damage to mucosal lining, intestinal permeability, tight junction protein expression, SCFA levels, and gut bacterial abundances. This higher degree of mucosal damage and pathological alteration in colonic mucosa prevented the previously reported protective actions of isomaltooligosaccharides as a prebiotic in HFD-fed mice. Overall, we present evidence that colonic precondition (gut permeability and mucosal lining) is an important factor in determination of HFD-induced changes in the colon, and success of diet-associated interventions (dietary fibers, pre/probiotics, etc.) is dependent on it.

The Role of the Gut Microbiome in Cancer Immunotherapy: Current Knowledge and Future Directions

Cancer immunotherapy is a treatment modality that aims to stimulate the anti-tumor immunity of the host to elicit favorable clinical outcomes. Immune checkpoint inhibitors (ICIs) gained traction due to the lasting effects and better tolerance in patients carrying solid tumors in comparison to conventional treatment. However, a significant portion of patients may present primary or acquired resistance (non-responders), and thus, they may have limited therapeutic outcomes. Resistance to ICIs can be derived from host-related, tumor-intrinsic, or environmental factors. Recent studies suggest a correlation of gut microbiota with resistance and response to immunotherapy as well as with the incidence of adverse events. Currently, preclinical and clinical studies aim to elucidate the unique microbial signatures related to ICI response and anti-tumor immunity, employing metagenomics and/or multi-omics. Decoding this complex relationship can provide the basis for manipulating the malleable structure of the gut microbiota to enhance therapeutic success. Here, we delve into the factors affecting resistance to ICIs, focusing on the intricate gut microbiome–immunity interplay. Additionally, we review clinical studies and discuss future trends and directions in this promising field.

Proanthocyanidins: Impact on Gut Microbiota and Intestinal Action Mechanisms in the Prevention and Treatment of Metabolic Syndrome

The metabolic syndrome (MS) is a cluster of risk factors, such as central obesity, hyperglycemia, dyslipidemia, and arterial hypertension, which increase the probability of causing premature mortality. The consumption of high-fat diets (HFD) is a major driver of the rising incidence of MS. In fact, the altered interplay between HFD, microbiome, and the intestinal barrier is being considered as a possible origin of MS. Consumption of proanthocyanidins (PAs) has a beneficial effect against the metabolic disturbances in MS. However, there are no conclusive results in the literature about the efficacy of PAs in improving MS. This review allows a comprehensive validation of the diverse effects of the PAs on the intestinal dysfunction in HFD-induced MS, differentiating between preventive and therapeutic actions. Special emphasis is placed on the impact of PAs on the gut microbiota, providing a system to facilitate comparison between the studies. PAs can modulate the microbiome toward a healthy profile and strength barrier integrity. Nevertheless, to date, published clinical trials to verify preclinical findings are scarce. Finally, the preventive consumption of PAs in MS-associated dysbiosis and intestinal dysfunction induced by HFD seems more successful than the treatment strategy.

Extent of Oral-Gut Transmission of Bacterial and Fungal Microbiota in Healthy Chinese Adults

Recent studies have provided evidence on the presence of an oral-gut microbiota axis in gastrointestinal diseases; however, whether a similar axis exists in healthy individuals is still in debate. Here, we characterized the bacterial and fungal microbiomes in paired oral rinse and stool samples collected from 470 healthy Chinese adults by sequencing the 16S rRNA V3-V4 and ITS1 regions, respectively. We hypothesized that there is limited oral-gut transmission of both the bacterial and fungal microbiota in healthy Chinese adults. Our results showed that the oral and gut microbiota in healthy individuals differed in taxonomic composition, alpha and beta diversity, metabolic potential, and network properties. Bayesian analysis showed that the vast majority of subjects had negligible or low bacterial and fungal oral-to-stool contribution. Detailed examination of the prevalent amplicon sequence variants (ASVs) also revealed limited cases of sharing between the oral and stool samples within the same individuals, except a few bacterial and fungal ASVs. Association analysis showed that sharing of the potentially transmissible fungal ASVs was associated with host factors, including an older age and a higher body mass index. Our findings indicate that oral-gut transmission of both bacterial and fungal microbiota in healthy adults is limited. Detection of a large amount of shared bacterial or fungal members between the oral and gut microbiome of an individual may indicate medical conditions that warrant detailed checkup. IMPORTANCE The oral-gut microbiota axis in health is a fundamentally important and clinically relevant topic; however, our current understanding of it remains biased and incomplete. By characterizing the bacterial and fungal microbiomes in paired oral rinse and stool samples from a large cohort of healthy Chinese adults, here we provided new evidence that oral-gut microbiota transmission is limited in non-Western population and across biological domains. Our study has established an important baseline of a healthy oral-gut microbiota axis, with which other disease conditions can be compared. Besides, our findings have practical implications that detection of a large amount of shared bacterial or fungal members between the oral cavity and gut within the same individual as an indicator of potential medical conditions.

Modified cereal bran (MCB) from finger millet, kodo millet, and rice bran prevents high-fat diet-induced metabolic derangements

Cereal bran consumption improves gastrointestinal and metabolic health. Unprocessed cereal brans have a limited shelf-life and contain anti-nutrient phytochemicals. In the present study, lipids and antinutrients (flavonoids, tannin, and polyphenol) were removed from finger millet, kodo millet and rice bran using chemo-enzymatic processing. The thus-obtained modified cereal brans (MCBs) were evaluated for their potential in preventing high fat diet (HFD)-induced obesity. C57BL/6 mice were fed a HFD or a HFD supplemented with 10% w/w modified finger millet bran (mFMB), modified kodo millet bran (mKMB), modified rice bran (mRB), or a combination of the modified brans (1 : 1 : 1) for twelve weeks. The MCBs reduced HFD-induced body weight gain, improved glucose homeostasis, decreased the Firmicutes/Bacteroidetes ratio, and increased the short chain fatty acid (SCFA) levels in the cecum. Liver dyslipidemia, oxidative stress, inflammation, visceral white adipose tissue (vWAT) hypertrophy, and lipolysis were also prevented by the MCBs. Among the individual MCBs, mRB showed a greater effect in preventing HFD-induced increase in the inflammatory cytokines (IL-6, TNF-α, and LPS) than mFMB and mKMB. mFMB and mKMB supplementation more significantly restored the relative abundance of Akkermansia muciniphila and butyrate-producing genera such as Lachnospiraceae, Eubacterium, and Ruminococcus than mRB. Ex vivo gut permeability assay, immunohistochemistry of tight junction proteins, and gene expression analysis in the colon revealed that the combination of three brans was better in preventing HFD-induced leaky gut in comparison to the individual brans. Hierarchical clustering analysis showed that the combination group was clustered closest to the NPD group, suggesting an additive effect. Our study implies that a combination of mFMB, mKMB, and mRB could be used as a nutraceutical or functional food ingredient for preventing HFD-induced gut derangements and associated metabolic complications.

Phage-encoded carbohydrate-interacting proteins in the human gut

In the human gastrointestinal tract, the gut mucosa and the bacterial component of the microbiota interact and modulate each other to accomplish a variety of critical functions. These include digestion aid, maintenance of the mucosal barrier, immune regulation, and production of vitamins, hormones, and other metabolites that are important for our health. The mucus lining of the gut is primarily composed of mucins, large glycosylated proteins with glycosylation patterns that vary depending on factors including location in the digestive tract and the local microbial population. Many gut bacteria have evolved to reside within the mucus layer and thus encode mucus-adhering and -degrading proteins. By doing so, they can influence the integrity of the mucus barrier and therefore promote either health maintenance or the onset and progression of some diseases. The viral members of the gut - mostly composed of bacteriophages - have also been shown to have mucus-interacting capabilities, but their mechanisms and effects remain largely unexplored. In this review, we discuss the role of bacteriophages in influencing mucosal integrity, indirectly via interactions with other members of the gut microbiota, or directly with the gut mucus via phage-encoded carbohydrate-interacting proteins. We additionally discuss how these phage-mucus interactions may influence health and disease states.

Alterations and correlations of gut microbiota, fecal, and serum metabolome characteristics in a rat model of alcohol use disorder

Background

Growing evidence suggests the gut microbiota and metabolites in serum or fecal may play a key role in the process of alcohol use disorder (AUD). However, the correlations of gut microbiota and metabolites in both feces and serum in AUD subjects are not well understood.

Methods

We established a rat model of AUD by a chronic intermittent ethanol voluntary drinking procedure, then the AUD syndromes, the gut microbiota, metabolomic profiling in feces and serum of the rats were examined, and correlations between gut microbiota and metabolites were analyzed.

Results

Ethanol intake preference increased and maintained at a high level in experimental rats. Anxiety-like behaviors was observed by open field test and elevated plus maze test after ethanol withdraw, indicating that the AUD rat model was successfully developed. The full length 16S rRNA gene sequencing showed AUD significantly changed the β-diversity of gut microbial communities, and significantly decreased the microbial diversity but did not distinctly impact the microbial richness. Microbiota composition significantly changed in AUD rats, such as the abundance of Romboutsia and Turicibacter were significantly increased, whereas uncultured_bacterium_o_Mollicutes_RF39 was decreased. In addition, the untargeted metabolome analysis revealed that many metabolites in both feces and serum were altered in the AUD rats, especially involved in sphingolipid metabolism and glycerophospholipid metabolism pathways. Finally, multiple correlations among AUD behavior, gut microbiota and co-changed metabolites were identified, and the metabolites were directly correlated with the gut microbiota and alcohol preference.

Conclusion

The altered metabolites in feces and serum are important links between the gut microbiota dysbiosis and alcohol preference in AUD rats, and the altered gut microbiota and metabolites can be potentially new targets for treating AUD.

Intestinal protein uptake and IgE-mediated food allergy

Food allergy is affecting 5-8% of young children and 2-4% of adults and seems to be increasing in prevalence. The cause of the increase in food allergy is largely unknown but proposed to be influenced by both environmental and lifestyle factors. Changes in intestinal barrier functions and increased uptake of dietary proteins have been suggested to have a great impact on food allergy. In this review, we aim to give an overview of the gastrointestinal digestion and intestinal barrier function and provide a more detailed description of intestinal protein uptake, including the various routes of epithelial transport, how it may be affected by both intrinsic and extrinsic factors, and the relation to food allergy. Further, we give an overview of in vitro, ex vivo and in vivo techniques available for evaluation of intestinal protein uptake and gut permeability in general. Proteins are digested by gastric, pancreatic and integral brush border enzymes in order to allow for sufficient nutritional uptake. Absorption and transport of dietary proteins across the epithelial layer is known to be dependent on the physicochemical properties of the proteins and their digestion fragments themselves, such as size, solubility and aggregation status. It is believed, that the greater an amount of intact protein or larger peptide fragments that is transported through the epithelial layer, and thus encountered by the mucosal immune system in the gut, the greater is the risk of inducing an adverse allergic response. Proteins may be absorbed across the epithelial barrier by means of various mechanisms, and studies have shown that a transcellular facilitated transport route unique for food allergic individuals are at play for transport of allergens, and that upon mediator release from mast cells an enhanced allergen transport via the paracellular route occurs. This is in contrast to healthy individuals where transcytosis through the enterocytes is the main route of protein uptake. Thus, knowledge on factors affecting intestinal barrier functions and methods for the determination of their impact on protein uptake may be useful in future allergenicity assessments and for development of future preventive and treatment strategies.

Enhancing intestinal barrier efficiency: A novel metabolic diseases therapy

Physiologically, the intestinal barrier plays a crucial role in homeostasis and nutrient absorption and prevents pathogenic entry, harmful metabolites, and endotoxin absorption. Recent advances have highlighted the association between severely damaged intestinal barriers and diabetes, obesity, fatty liver, and cardiovascular diseases. Evidence indicates that an abated intestinal barrier leads to endotoxemia associated with systemic inflammation, insulin resistance, diabetes, and lipid accumulation, accelerating obesity and fatty liver diseases. Nonetheless, the specific mechanism of intestinal barrier damage and the effective improvement of the intestinal barrier remain to be explored. Here, we discuss the crosstalk between changes in the intestinal barrier and metabolic disease. This paper also highlights how to improve the gut barrier from the perspective of natural medicine, gut microbiota remodeling, lifestyle interventions, and bariatric surgery. Finally, potential challenges and prospects for the regulation of the gut barrier-metabolic disease axis are discussed, which may provide theoretical guidance for the treatment of metabolic diseases.

Characterization of the Cafeteria Diet as Simulation of the Human Western Diet and Its Impact on the Lipidomic Profile and Gut Microbiota in Obese Rats

The obesity pandemic has been strongly associated with the Western diet, characterized by the consumption of ultra-processed foods. The Western lifestyle causes gut dysbiosis leading to impaired fatty acid metabolism. Therefore, this study aimed to evaluate shifts in gut microbiota and correlate these with serum fatty acid profiles in male Wistar rats fed a cafeteria diet. Ten male rats were fed with standard diet (CTL, n = 5) and cafeteria diet (CAF, n = 5) for fifteen weeks. Body weight and food intake were recorded once and three times per week, respectively. At the end of the study, fresh fecal samples were collected, tissues were removed, and serum samples were obtained for further analyses. Gut microbiota was analyzed by sequencing the V3-V4 region of 16S rRNA gene. Serum fatty acid profiles were fractioned and quantified via gas chromatography. The CAF diet induced an obese phenotype accompanied by impaired serum fatty acids, finding significantly higher proportions of total saturated fatty acids (SFAs) and C20:3 n-6, and lower C18:1 n-7 and C18:3 n-3 in the phospholipid (PL) fraction. Furthermore, circulating C10:0, total n-3 and n-7 decreased and total monounsaturated fatty acids (MUFAs), including oleic acid C18:1 n-9, increased in the cholesterol ester (CE) fraction. The obesity metabotype may be mediated by gut dysbiosis caused by a cafeteria diet rich in C16:0, C18:0, C18:1 n-9 and C18:2 n-6 fatty acids resulting in a 34:1 omega-6/omega-3 ratio. Therefore, circulating C10:0 was associated with several genera bacteria such as Prevotella (positive) and Anaerotruncus (negative). Two classes of Firmicutes, Bacilli and Erysipelotrichi, were positively correlated with PL- C20:3 n-6 and CE- 18:1 n-9, respectively. TM7 and Bacteroidetes were inversely correlated with PL-SFAs and CE- 18:2 n-6, respectively.

Probiotic Bifidobacterium longum subsp. longum Protects against Cigarette Smoke-Induced Inflammation in Mice

Bifidobacterium are prominent gut commensals that produce the short-chain fatty acid (SCFA) acetate, and they are often used as probiotics. Connections between the gut and the lung, termed the gut-lung axis, are regulated by the microbiome. The gut-lung axis is increasingly implicated in cigarette smoke-induced diseases, and cigarette smoke exposure has been associated with depletion of Bifidobacterium species. In this study, we assessed the impact of acetate-producing Bifidobacterium longum subsp. longum (WT) and a mutant strain with an impaired acetate production capacity (MUT) on cigarette smoke-induced inflammation. The mice were treated with WT or MUT B. longum subsp. longum and exposed to cigarette smoke for 8 weeks before assessments of lung inflammation, lung tissue gene expression and cecal SCFAs were performed. Both strains of B. longum subsp. longum reduced lung inflammation, inflammatory cytokine expression and adhesion factor expression and alleviated cigarette smoke-induced depletion in caecum butyrate. Thus, the probiotic administration of B. longum subsp. longum, irrespective of its acetate-producing capacity, alleviated cigarette smoke-induced inflammation and the depletion of cecal butyrate levels.

Short-Chain Fatty Acid Receptors and Blood Pressure Regulation: Council on Hypertension Mid-Career Award for Research Excellence 2021

The gut microbiome influences host physiology and pathophysiology through several pathways, one of which is microbial production of chemical metabolites which interact with host signaling pathways. Short-chain fatty acids (SCFAs) are a class of gut microbial metabolites known to activate multiple signaling pathways in the host. Growing evidence indicates that the gut microbiome is linked to blood pressure, that SCFAs modulate blood pressure regulation, and that delivery of exogenous SCFAs lowers blood pressure. Given that hypertension is a key risk factor for cardiovascular disease, the examination of novel contributors to blood pressure regulation has the potential to lead to novel approaches or treatments. Thus, this review will discuss SCFAs with a focus on their host G protein-coupled receptors including GPR41 (G protein-coupled receptor 41), GPR43, and GPR109A, as well as OLFR78 (olfactory receptor 78) and OLFR558. This includes a discussion of the ligand profiles, G protein coupling, and tissue distribution of each receptor. We will also review phenotypes relevant to blood pressure regulation which have been reported to date for Gpr41, Gpr43, Gpr109a, and Olfr78 knockout mice. In addition, we will consider how SCFA signaling influences physiology at baseline, and, how SCFA signaling may contribute to blood pressure regulation in settings of hypertension. In sum, this review will integrate current knowledge regarding how SCFAs and their receptors regulate blood pressure.

Longitudinal analysis of exposure to a low concentration of oxytetracycline on the zebrafish gut microbiome

Oxytetracycline, a widely produced and administered antibiotic, is uncontrollably released in low concentrations in various types of environments. However, the impact of exposure to such low concentrations of antibiotics on the host remains poorly understood. In this study, we exposed zebrafish to a low concentration (5,000 ng/L) of oxytetracycline for 1 month, collected samples longitudinally (Baseline, and Days 3, 6, 9, 12, 24, and 30), and elucidated the impact of exposure on microbial composition, antibiotic resistance genes, mobile genetic elements, and phospholipid metabolism pathway through comparison of the sequenced data with respective sequence databases. We identified Pseudomonas aeruginosa, a well-known pathogen, to be significantly positively associated with the duration of oxytetracycline exposure (Adjusted P = 5.829e-03). Several tetracycline resistance genes (e.g., tetE) not only showed significantly higher abundance in the exposed samples but were also positively associated with the duration of exposure (Adjusted P = 1.114e-02). Furthermore, in the exposed group, the relative abundance of genes involved in phospholipid metabolism had also decreased. Lastly, we characterized the impact of exposure on zebrafish intestinal structure and found that the goblet cell counts were decreased (~82%) after exposure. Overall, our results show that a low concentration of oxytetracycline can increase the abundance of pathogenic bacteria and lower the abundance of key metabolic pathways in the zebrafish gut microbiome that can render them prone to bacterial infections and health-associated complications.

Unhealthy Diets Induce Distinct and Regional Effects on Intestinal Inflammatory Signalling Pathways and Long-Lasting Metabolic Dysfunction in Rats

The intestinal epithelium is a principal site for environmental agents’ detection. Several inflammation- and stress-related signalling pathways have been identified as key players in these processes. However, it is still unclear how the chronic intake of inadequate nutrients triggers inflammatory signalling pathways in different intestinal regions. We aimed to evaluate the impact of unhealthy dietary patterns, starting at a younger age, and the association with metabolic dysfunction, intestinal inflammatory response, and obesity in adulthood. A rat model was used to evaluate the effects of the consumption of sugary beverages (HSD) and a Western diet (WD), composed of ultra-processed foods. Both diets showed a positive correlation with adiposity index, but a positive correlation was found between the HSD diet and the levels of blood glucose and triglycerides, whereas the WD diet correlated positively with triglyceride levels. Moreover, a distinct inflammatory response was associated with either the WD or HSD diets. The WD induced an increase in TLR2, TLR4, and nuclear factor-kappa B (NF-κB) intestinal gene expression, with higher levels in the colon and overexpression of the inducible nitric oxide synthase. In turn, the HSD diet induced activation of the TLR2-mediated NF-κB signalling pathway in the small intestine. Altogether, these findings support the concept that early intake of unhealthy foods and nutrients are a main exogenous signal for disturbances of intestinal immune mechanisms and in a region-specific manner, ultimately leading to obesity-related disorders in later life.

Diet, microbiota, and the mucus layer: The guardians of our health

The intestinal tract is an ecosystem in which the resident microbiota lives in symbiosis with its host. This symbiotic relationship is key to maintaining overall health, with dietary habits of the host representing one of the main external factors shaping the microbiome-host relationship. Diets high in fiber and low in fat and sugars, as opposed to Western and high-fat diets, have been shown to have a beneficial effect on intestinal health by promoting the growth of beneficial bacteria, improve mucus barrier function and immune tolerance, while inhibiting pro-inflammatory responses and their downstream effects. On the contrary, diets low in fiber and high in fat and sugars have been associated with alterations in microbiota composition/functionality and the subsequent development of chronic diseases such as food allergies, inflammatory bowel disease, and metabolic disease. In this review, we provided an updated overview of the current understanding of the connection between diet, microbiota, and health, with a special focus on the role of Western and high-fat diets in shaping intestinal homeostasis by modulating the gut microbiota.

Nasal Microbiota, Olfactory Health, Neurological Disorders and Aging—A Review

The nasal region is one of the distinct environments for the survival of various microbiota. The human microbial niche begins to inhabit the human body right from birth, and the microbiota survive as commensals or opportunistic pathogens throughout the life of humans in their bodies in various habitats. These microbial communities help to maintain a healthy microenvironment by preventing the attack of pathogens and being involved in immune regulation. Any dysbiosis of microbiota residing in the mucosal surfaces, such as the nasal passages, guts, and genital regions, causes immune modulation and severe infections. The coexistence of microorganisms in the mucosal layers of respiratory passage, resulting in infections due to their co-abundance and interactions, and the background molecular mechanisms responsible for such interactions, need to be considered for investigation. Additional clinical evaluations can explain the interactions among the nasal microbiota, nasal dysbiosis and neurodegenerative diseases (NDs). The respiratory airways usually act as a substratum place for the microbes and can act as the base for respiratory tract infections. The microbial metabolites and the microbes can cross the blood–brain barrier and may cause NDs, such as Parkinson’s disease (PD), Alzheimer’s disease (AD), and multiple sclerosis (MS). The scientific investigations on the potential role of the nasal microbiota in olfactory functions and the relationship between their dysfunction and neurological diseases are limited. Recently, the consequences of the severe acute respiratory syndrome coronavirus (SARS-CoV-2) in patients with neurological diseases are under exploration. The crosstalk between the gut and the nasal microbiota is highly influential, because their mucosal regions are the prominent microbial niche and are connected to the olfaction, immune regulation, and homeostasis of the central nervous system. Diet is one of the major factors, which strongly influences the mucosal membranes of the airways, gut, and lung. Unhealthy diet practices cause dysbiosis in gut microbiota and the mucosal barrier. The current review summarizes the interrelationship between the nasal microbiota dysbiosis, resulting olfactory dysfunctions, and the progression of NDs during aging and the involvement of coronavirus disease 2019 in provoking the NDs.

The Dietary Inflammatory Index and Early COPD: Results from the National Health and Nutrition Examination Survey

We examined 3962 people aged 20 to 49 years who had information on spirometry testing and underwent a 24 h dietary recall interview from the 2007-2012 National Health and Nutrition Examination Survey (NHANES) and used multivariable logistic regression to evaluate associations between Dietary Inflammatory Index (DII, a pro-inflammatory diet) and early COPD and lung function. The overall prevalence of early COPD was 5.05%. Higher DII was associated with increased odds of early COPD (quartile 4 vs. 1, the OR = 1.657, 95% CI = 1.100-2.496, p = 0.0156). In a full-adjusted model, each unit of increase in DII score was associated with a 90.3% increase in the risk of early COPD. Higher DII is significantly associated with lower FEV1 and FVC among individuals with early COPD, each unit increment in the DII was significantly associated with 0.43 L-0.58 L decrements in FEV1 (β = -0.43, 95% CI = -0.74, -0.12) and FVC (β = -0.58, 95% CI = -1.01, -0.16). These findings demonstrate that higher consumption of a pro-inflammatory diet may contribute to an increased risk of early COPD and lower lung function, and further support dietary interventions as part of a healthy lifestyle in order to preserve lung function and prevent or improve COPD.

Effects of Bile Acid Modulation by Dietary Fat, Cholecystectomy, and Bile Acid Sequestrant on Energy, Glucose, and Lipid Metabolism and Gut Microbiota in Mice

Bile acid metabolism, involved with the digestion and absorption of nutrients in the gut, is linked to the gut microbiota community, greatly impacting the host’s metabolism. We examined the hypothesis that the modulation of bile acid metabolism by dietary fat contents, gallbladder removal (GBX; cholecystectomy), and bile acid sequestrant (BAS; cholestyramine) treatment could alter energy, glucose, and lipid metabolism through the changes in the gut microbiota. Mice were randomly assigned to the following six groups: (1) Sham GBX surgery (Sham) + low fat/high carbohydrate diet (LFD), (2) Sham + high fat diet (HFD), (3) Sham + HFD + BAS, (4) GBX + LFD, (5) GBX + HFD, and (6) GBX + HFD + BAS. BAS groups received 2% cholestyramine. After an 8-week intervention, energy, glucose, and lipid metabolism, and the gut microbiota community were measured. HFD groups exhibited higher body weight gain than LFD, and GBX increased the weight gain comped to Sham groups regardless of BAS in HFD (p < 0.05). Homeostatic model assessment for insulin resistance (HOMA-IR) was higher in HFD than LFD, and GBX increased it regardless of BAS. Serum lipid profiles were worsened in GBX + HFD compared to Sham + LFD, whereas BAS alleviated them, except for serum HDL cholesterol. Hepatic tumor-necrosis-factor-α (TNF-α) mRNA expression and lipid peroxide contents increased with GBX and BAS treatment compared to Sham and no BAS treatment (p < 0.05). Hepatic mRNA expression of sterol regulatory element-binding transcription factor 1c (SREBP1c) and peroxisome proliferator-activated receptor gamma (PPAR-γ) exhibited the same trend as that of tumor necrosis factor-α (TNF-α). The α-diversity of gut bacteria decreased in GBX + HFD and increased in GBX + HFD + BAS. Akkermentia, Dehalobacterium, SMB53, and Megamonas were high in the Sham + LFD, and Veillonella and Streptococcus were rich in the Sham + HFD, while Oscillospira and Olsenella were high in Sham + HFD + BAS (p < 0.05). GBX + LFD increased Lactobacillus and Sutterella while GBX + HFD + BAS elevated Clostridium, Alistipes, Blautia, Eubacterium, and Coprobacillus (p < 0.05). In conclusion, the modulation of bile acid metabolism influences energy, glucose, and lipid metabolisms, and it might be linked to changes in the gut microbiota by bile acid metabolism modulation.

Human Gut Microbiome Across Different Lifestyles: From Hunter-Gatherers to Urban Populations

Human lifestyle and its relationship with the human microbiome has been a line of research widely studied. This is because, throughout human history, civilizations have experienced different environments and lifestyles that could have promoted changes in the human microbiome. The comparison between industrialized and non-industrialized human populations in several studies has allowed to observe variation in the microbiome structure due to the population lifestyle. Nevertheless, the lifestyle of human populations is a gradient where several subcategories can be described. Yet, it is not known how these different lifestyles of human populations affect the microbiome structure on a large scale. Therefore, the main goal of this work was the collection and comparison of 16S data from the gut microbiome of populations that have different lifestyles around the world. With the data obtained from 14 studies, it was possible to compare the gut microbiome of 568 individuals that represent populations of hunter-gatherers, agricultural, agropastoral, pastoral, and urban populations. Results showed that industrialized populations present less diversity than those from non-industrialized populations, as has been described before. However, by separating traditional populations into different categories, we were able to observe patterns that cannot be appreciated by encompassing the different traditional lifestyles in a single category. In this sense, we could confirm that different lifestyles exhibit distinct alpha and beta diversity. In particular, the gut microbiome of pastoral and agropastoral populations seems to be more similar to those of urban populations according to beta diversity analysis. Beyond that, beta diversity analyses revealed that bacterial composition reflects the different lifestyles, representing a transition from hunters-gatherers to industrialized populations. Also, we found that certain groups such as Bacteoidaceae, Lanchospiraceae, and Rickenellaceae have been favored in the transition to modern societies, being differentially abundant in urban populations. Thus, we could hypothesize that due to adaptive/ecological processes; multifunctional bacterial groups (e.g., Bacteroidaceae) could be replacing some functions lost in the transition to modern lifestyle.

Emerging trends and hotspot in gut-lung axis research from 2011 to 2021: a bibliometrics analysis

BACKGROUND

Increasing attention has been paid to the potential relationship between gut and lung. The bacterial dysbiosis in respiratory tract and intestinal tract is related to inflammatory response and the progress of lung diseases, and the pulmonary diseases could be improved by regulating the intestinal microbiome. This study aims to generate the knowledge map to identify major the research hotspots and frontier areas in the field of gut-lung axis.

MATERIALS AND METHODS

Publications related to the gut-lung axis from 2011 to 2021 were identified from the Web of Science Core Collection. CiteSpace 5.7.R2 software was used to analyze the publication years, journals, countries, institutions, and authors. Reference co-citation network has been plotted, and the keywords were used to analyze the research hotspots and trends.

RESULTS

A total of 3315 publications were retrieved and the number of publications per year increased over time. Our results showed that Plos One (91 articles) was the most active journal and The United States (1035 articles) published the most articles. We also observed the leading institution was the University of Michigan (48 articles) and Huffnagle Gary B, Dickson Robert P and Hansbro Philip M, who have made outstanding contributions in this field.

CONCLUSION

The Inflammation, Infection and Disease were the hotspots, and the regulation of intestinal flora to improve the efficacy of immunotherapy in lung cancer was the research frontier. The research has implications for researchers engaged in gut-lung axis and its associated fields.

Involvement and therapeutic implications of airway epithelial barrier dysfunction in type 2 inflammation of asthma

Type 2 inflammation is a complex immune response and primary mechanism for several common allergic diseases including allergic rhinitis, allergic asthma, atopic dermatitis, and chronic rhinosinusitis with nasal polyps. It is the predominant type of immune response against helminths to prevent their tissue infiltration and induce their expulsion. Recent studies suggest that epithelial barrier dysfunction contributes to the development of type 2 inflammation in asthma, which may partly explain the increasing prevalence of asthma in China and around the globe. The epithelial barrier hypothesis has recently been proposed and has received great interest from the scientific community. The development of leaky epithelial barriers leads to microbial dysbiosis and the translocation of bacteria to inter- and sub-epithelial areas and the development of epithelial tissue inflammation. Accordingly, preventing the impairment and promoting the restoration of a deteriorated airway epithelial barrier represents a promising strategy for the treatment of asthma. This review introduces the interaction between type 2 inflammation and the airway epithelial barrier in asthma, the structure and molecular composition of the airway epithelial barrier, and the assessment of epithelial barrier integrity. The role of airway epithelial barrier disruption in the pathogenesis of asthma will be discussed. In addition, the possible mechanisms underlying the airway epithelial barrier dysfunction induced by allergens and environmental pollutants, and current treatments to restore the airway epithelial barrier are reviewed.

Validating Accuracy of a Mobile Application against Food Frequency Questionnaire on Key Nutrients with Modern Diets for mHealth Era

In preparation for personalized nutrition, an accurate assessment of dietary intakes on key essential nutrients using smartphones can help promote health and reduce health risks across vulnerable populations. We, therefore, validated the accuracy of a mobile application (app) against Food Frequency Questionnaire (FFQ) using artificial intelligence (AI) machine-learning-based analytics, assessing key macro- and micro-nutrients across various modern diets. We first used Bland and Altman analysis to identify and visualize the differences between the two measures. We then applied AI-based analytics to enhance prediction accuracy, including generalized regression to identify factors that contributed to the differences between the two measures. The mobile app underestimated most macro- and micro-nutrients compared to FFQ (ranges: -5% for total calories, -19% for cobalamin, -33% for vitamin E). The average correlations between the two measures were 0.87 for macro-nutrients and 0.84 for micro-nutrients. Factors that contributed to the differences between the two measures using total calories as an example, included caloric range (1000-2000 versus others), carbohydrate, and protein; for cobalamin, included caloric range, protein, and Chinese diet. Future studies are needed to validate actual intakes and reporting of various diets, and to examine the accuracy of mobile App. Thus, a mobile app can be used to support personalized nutrition in the mHealth era, considering adjustments with sources that could contribute to the inaccurate estimates of nutrients.