Precision synbiotics increase gut microbiome diversity and improve gastrointestinal symptoms in a pilot open-label study for autism spectrum disorder

The efficacy of prebiotics and probiotics (synbiotics when combined) to improve symptoms associated with autism spectrum disorder (ASD) has shown considerable inter-study variation, likely due to the complex, heterogeneous nature of the disorder and its associated behavioral, developmental, and gastrointestinal symptoms. Here, we present a precision synbiotic supplementation study in 296 children and adults diagnosed with ASD versus 123 age-matched neurotypical controls. One hundred seventy ASD participants completed the study. Baseline and post-synbiotic assessment of ASD and gastrointestinal (GI) symptoms and deep metagenomic sequencing were performed. Within the ASD cohort, there were significant differences in microbes between subpopulations based on the social responsiveness scale (SRS2) survey (Prevotella spp., Bacteroides, Fusicatenibacter, and others) and gluten and dairy-free diets (Bifidobacterium spp., Lactococcus, Streptococcus spp., and others). At the baseline, the ASD cohort maintained a lower taxonomic alpha diversity and significant differences in taxonomic composition, metabolic pathways, and gene families, with a greater proportion of potential pathogens, including Shigella, Klebsiella, and Clostridium, and lower proportions of beneficial microbes, including Faecalibacterium compared to controls. Following the 3-month synbiotic supplementation, the ASD cohort showed increased taxonomic alpha diversity, shifts in taxonomy and metabolic pathway potential, and improvements in some ASD-related symptoms, including a significant reduction in GI discomfort and overall improved language, comprehension, cognition, thinking, and speech. However, the open-label study design may include some placebo effects. In summary, we found that precision synbiotics modulated the gut microbiome and could be used as supplementation to improve gastrointestinal and ASD-related symptoms.

IMPORTANCE

Autism spectrum disorder (ASD) is prevalent in 1 out of 36 children in the United States and contributes to health, financial, and psychological burdens. Attempts to identify a gut microbiome signature of ASD have produced varied results. The limited pre-clinical and clinical population sizes have hampered the success of these trials. To understand the microbiome associated with ASD, we employed whole metagenomic shotgun sequencing to classify microbial composition and genetic functional potential. Despite being one of the most extensive ASD post-synbiotic assessment studies, the results highlight the complexity of performing such a case-control supplementation study in this population and the potential for a future therapeutic approach in ASD.

Virion-incorporated CD14 enables HIV-1 to bind LPS and initiate TLR4 signaling in immune cells

HIV-1 has a broad range of nuanced interactions with the immune system, and the incorporation of cellular proteins by nascent virions continues to redefine our understanding of the virus-host relationship. Proteins located at the sites of viral egress can be selectively incorporated into the HIV-1 envelope, imparting new functions and phenotypes onto virions, and impacting viral spread and disease. Using virion capture assays and western blot, we show that HIV-1 can incorporate the myeloid antigen CD14 into its viral envelope. Virion-incorporated CD14 remained biologically active and able to bind its natural ligand, bacterial lipopolysaccharide (LPS), as demonstrated by flow virometry and immunoprecipitation assays. Using a Toll-like receptor 4 (TLR4) reporter cell line, we also demonstrated that virions with bound LPS can trigger TLR4 signaling to activate transcription factors that regulate inflammatory gene expression. Complementary assays with THP-1 monocytes demonstrated enhanced secretion of inflammatory cytokines like tumor necrosis factor alpha (TNF-α) and the C-C chemokine ligand 5 (CCL5), when exposed to LPS-loaded virus. These data highlight a new type of interplay between HIV-1 and the myeloid cell compartment, a previously well-established cellular contributor to HIV-1 pathogenesis and inflammation. Persistent gut inflammation is a hallmark of chronic HIV-1 infection, and contributing to this effect is the translocation of microbes across the gut epithelium. Our data herein provide proof of principle that virion-incorporated CD14 could be a novel mechanism through which HIV-1 can drive chronic inflammation, facilitated by HIV-1 particles binding bacterial LPS and initiating inflammatory signaling in TLR4-expressing cells.IMPORTANCEHIV-1 establishes a lifelong infection accompanied by numerous immunological changes. Inflammation of the gut epithelia, exacerbated by the loss of mucosal T cells and cytokine dysregulation, persists during HIV-1 infection. Feeding back into this loop of inflammation is the translocation of intestinal microbes across the gut epithelia, resulting in the systemic dissemination of bacterial antigens, like lipopolysaccharide (LPS). Our group previously demonstrated that the LPS receptor, CD14, can be readily incorporated by HIV-1 particles, supporting previous clinical observations of viruses derived from patient plasma. We now show that CD14 can be incorporated by several primary HIV-1 isolates and that this virion-incorporated CD14 can remain functional, enabling HIV-1 to bind to LPS. This subsequently allowed CD14+ virions to transfer LPS to monocytic cells, eliciting pro-inflammatory signaling and cytokine secretion. We posit here that virion-incorporated CD14 is a potential contributor to the dysregulated immune responses present in the setting of HIV-1 infection.

Effects of Combined Live Bifidobacterium, Lactobacillus, Enterococcus, and Bacillus Cereus Tablets on the Structure and Function of the Intestinal Flora in Rabbits Undergoing Hepatic Artery Infusion Chemotherapy

Few studies have explored the biological mechanism by which probiotics alleviate adverse reactions to chemotherapy drugs after local hepatic chemotherapy perfusion by regulating the intestinal flora. This study investigates the effects of Combined Live Bifidobacterium, Lactobacillus, Enterococcus, and Bacillus Cereus Tablets on the intestinal microbial structure and intestinal barrier function, as well as the potential mechanism in rabbits after local hepatic chemotherapy infusion. Eighteen New Zealand White rabbits were randomly divided into a control group, a hepatic local chemotherapy perfusion group, and a hepatic local chemotherapy perfusion + Combined Live Bifidobacterium, Lactobacillus, Enterococcus, and Bacillus Cereus Tablets group to assess the effects of Combined Live Bifidobacterium, Lactobacillus, Enterococcus, and Bacillus Cereus Tablets on the adverse reactions. The administration of Combined Live Bifidobacterium, Lactobacillus, Enterococcus, and Bacillus Cereus Tablets alleviated the intestinal flora disorder caused by local hepatic perfusion chemotherapy, promoted the growth of beneficial bacteria, and inhibited the growth of harmful bacteria. The Combined Live Bifidobacterium, Lactobacillus, Enterococcus, and Bacillus Cereus Tablets also reduced the levels of serum pro-inflammatory cytokines and liver injury factors induced by local hepatic perfusion chemotherapy. Our findings indicate that Combined Live Bifidobacterium, Lactobacillus, Enterococcus, and Bacillus Cereus Tablets can ameliorate the toxicity and side effects of chemotherapy by regulating intestinal flora, blocking pro-inflammatory cytokines, reducing liver injury factors, and repairing the intestinal barrier. Probiotics may be used as a potential alternative therapeutic strategy to prevent the adverse reactions caused by chemotherapy with local hepatic perfusion.

Deciphering the Chemical Language of the Immunomodulatory Properties of Veillonella parvula Lipopolysaccharide

Veillonella parvula, prototypical member of the oral and gut microbiota, is at times commensal yet also potentially pathogenic. The definition of the molecular basis tailoring this contrasting behavior is key for broadening our understanding of the microbiota-driven pathogenic and/or tolerogenic mechanisms that take place within our body. In this study, we focused on the chemistry of the main constituent of the outer membrane of V. parvula, the lipopolysaccharide (LPS). LPS molecules indeed elicit pro-inflammatory and immunomodulatory responses depending on their chemical structures. Herein we report the structural elucidation of the LPS from two strains of V. parvula and show important and unprecedented differences in both the lipid and carbohydrate moieties, including the identification of a novel galactofuranose and mannitol-containing O-antigen repeating unit for one of the two strains. Furthermore, by harnessing computational studies, in vitro human cell models, as well as lectin binding solid-phase assays, we discovered that the two chemically diverse LPS immunologically behave differently and have attempted to identify the molecular determinant(s) governing this phenomenon. Whereas pro-inflammatory potential has been evidenced for the lipid A moiety, by contrast a plausible "immune modulating" action has been proposed for the peculiar O-antigen portion.

Modulation of gut microbiota with probiotics as a strategy to counteract endogenous and exogenous neurotoxicity

The existing data demonstrate that probiotic supplementation affords protective effects against neurotoxicity of exogenous (e.g., metals, ethanol, propionic acid, aflatoxin B1, organic pollutants) and endogenous (e.g., LPS, glucose, Aβ, phospho-tau, α-synuclein) agents. Although the protective mechanisms of probiotic treatments differ between various neurotoxic agents, several key mechanisms at both the intestinal and brain levels seem inherent to all of them. Specifically, probiotic-induced improvement in gut microbiota diversity and taxonomic characteristics results in modulation of gut-derived metabolite production with increased secretion of SFCA. Moreover, modulation of gut microbiota results in inhibition of intestinal absorption of neurotoxic agents and their deposition in brain. Probiotics also maintain gut wall integrity and inhibit intestinal inflammation, thus reducing systemic levels of LPS. Centrally, probiotics ameliorate neurotoxin-induced neuroinflammation by decreasing LPS-induced TLR4/MyD88/NF-κB signaling and prevention of microglia activation. Neuroprotective mechanisms of probiotics also include inhibition of apoptosis and oxidative stress, at least partially by up-regulation of SIRT1 signaling. Moreover, probiotics reduce inhibitory effect of neurotoxic agents on BDNF expression, on neurogenesis, and on synaptic function. They can also reverse altered neurotransmitter metabolism and exert an antiamyloidogenic effect. The latter may be due to up-regulation of ADAM10 activity and down-regulation of presenilin 1 expression. Therefore, in view of the multiple mechanisms invoked for the neuroprotective effect of probiotics, as well as their high tolerance and safety, the use of probiotics should be considered as a therapeutic strategy for ameliorating adverse brain effects of various endogenous and exogenous agents.

Bacterial lipopolysaccharide forms aggregates with apolipoproteins in male and female rat brains after ethanol binges

Alcohol binge drinking allows the translocation of bacterial lipopolysaccharide (LPS) from the gut to the blood, which activates the peripheral immune system with consequences in neuroinflammation. A possible access/direct signaling of LPS to/in the brain has not yet been described under alcohol abuse conditions. Apolipoproteins are compounds altered by alcohol with high affinity to LPS which may be involved in its transport to the brain or in its elimination. Here, we explored the expression of small components of LPS, in its free form or bound to apolipoproteins, in the brain of female and male rats exposed to alcohol binges. Animals received ethanol oral gavages (3 g/kg every 8 h) for 4 days. LPS or its components (Lipid A and core), LPS-binding protein, corticosterone, lipoproteins (HDL, LDL), apolipoproteins (ApoAI, ApoB, and ApoE), and their receptors were measured in plasma and/or in nonperfused prefrontal cortex (PFC) and cerebellum. Brain LipidA-apolipoprotein aggregates were determined by Western blotting and confirmed by co-immunoprecipitation. In animals exposed to alcohol binges: 1) plasma LPS-binding protein was elevated in both sexes; 2) females showed elevations in plasma ApoAI and corticosterone levels; 3) Lipid A formed aggregates with ApoAI in the female PFC and with ApoB in males, the latter showing Toll-like receptor 4 upregulation in PFC but not females. These results suggest that small bacterial components are present within the brain, forming aggregates with different apolipoproteins, depending on the sex, after alcohol binge intoxications. Results may have implications for the crosstalk between alcohol, LPS, and neuroinflammation.

Wheat Bran Polyphenols Ameliorate DSS-Induced Ulcerative Colitis in Mice by Suppressing MAPK/NF-κB Inflammasome Pathways and Regulating Intestinal Microbiota

Wheat bran (WB) is the primary by-product of wheat processing and contains a high concentration of bioactive substances such as polyphenols. This study analyzed the qualitative and quantitative components of polyphenols in wheat bran and their effects on ulcerative colitis (UC) using the dextran sulfate sodium (DSS)-induced colitis model in mice. The potential mechanism of wheat bran polyphenols (WBP) was also examined. Our findings indicate that the main polyphenol constituents of WBP were phenolic acids, including vanillic acid, ferulic acid, caffeic acid, gallic acid, and protocatechuic acid. Furthermore, WBP exerted remarkable protective effects against experimental colitis. This was achieved by reducing the severity of colitis and improving colon morphology. Additionally, WBP suppressed colonic inflammation via upregulation of the anti-inflammatory cytokine IL-10 and downregulation of pro-inflammatory cytokines (TNF-α, IL-6, IL-1β) in colon tissues. Mechanistically, WBP ameliorated DSS-induced colitis in mice by inhibiting activation of the MAPK/NF-κB pathway. In addition, microbiome analysis results suggested that WBP modulated the alteration of gut microbiota caused by DSS, with an enhancement in the ratio of Firmicutes/Bacteroidetes and adjustments in the number of Helicobacter, Escherichia-Shigella, Akkermansia, Lactobacillus, Lachnospiraceae_NK4A136_group at the genus level. To conclude, the findings showed that WBP has excellent prospects in reducing colonic inflammation in UC mice.

Galectin from Trichinella spiralis alleviates DSS-induced colitis in mice by regulating the intestinal microbiota

According to numerous reports, Trichinella spiralis (T. spiralis) and its antigens can reduce intestinal inflammation by modulating regulatory immunological responses in the host to maintain immune homeostasis. Galectin has been identified as a protein that is produced by T. spiralis, and its characterization revealed this protein has possible immune regulatory activity. However, whether recombinant T. spiralis galectin (rTs-gal) can cure dextran sulfate sodium (DSS)-induced colitis remains unknown. Here, the ability of rTs-gal to ameliorate experimental colitis in mice with inflammatory bowel disease (IBD) as well as the potential underlying mechanism were investigated. The disease activity index (DAI), colon shortening, inflammatory cell infiltration, and histological damage were used as indicators to monitor clinical symptoms of colitis. The results revealed that the administration of rTs-gal ameliorated these symptoms. According to Western blotting and ELISA results, rTs-gal may suppress the excessive inflammatory response-mediated induction of TLR4, MyD88, and NF-κB expression in the colon. Mice with colitis exhibit disruptions in the gut flora, including an increase in gram-negative bacteria, which in turn can result in increased lipopolysaccharide (LPS) production. However, injection of rTs-gal may inhibit changes in the gut microbiota, for example, by reducing the prevalence of Helicobacter and Bacteroides, which produce LPS. The findings of the present study revealed that rTs-gal may inhibit signalling pathways that involve enteric bacteria-derived LPS, TLR4, and NF-κB in mice with DSS-induced colitis and attenuate DSS-induced colitis in animals by modulating the gut microbiota. These findings shed additional light on the immunological processes underlying the beneficial effects of helminth-derived proteins in medicine.

Gut microbiota facilitate chronic spontaneous urticaria

Chronic spontaneous urticaria (CSU) comes with gut dysbiosis, but its relevance remains elusive. Here we use metagenomics sequencing and short-chain fatty acids metabolomics and assess the effects of human CSU fecal microbial transplantation, Klebsiella pneumoniae, Roseburia hominis, and metabolites in vivo. CSU gut microbiota displays low diversity and short-chain fatty acids production, but high gut Klebsiella pneumoniae levels, negatively correlates with blood short-chain fatty acids levels and links to high disease activity. Blood lipopolysaccharide levels are elevated, link to rapid disease relapse, and high gut levels of conditional pathogenic bacteria. CSU microbiome transfer and Klebsiella pneumoniae transplantation facilitate IgE-mediated mast cell(MC)-driven skin inflammatory responses and increase intestinal permeability and blood lipopolysaccharide accumulation in recipient mice. Transplantation of Roseburia hominis and caproate administration protect recipient mice from MC-driven skin inflammation. Here, we show gut microbiome alterations, in CSU, may reduce short-chain fatty acids and increase lipopolysaccharide levels, respectively, and facilitate MC-driven skin inflammation.

Antigenic operon fragmentation and diversification mechanism in Bacteroidota impacts gut metagenomics and pathobionts in Crohn's disease microlesions

Comensal Bacteroidota (Bacteroidota) and Enterobacteriacea are often linked to gut inflammation. However, the causes for variability of pro-inflammatory surface antigens that affect gut commensal/opportunistic dualism in Bacteroidota remain unclear. By using the classical lipopolysaccharide/O-antigen 'rfb operon' in Enterobacteriaceae as a surface antigen model (5-rfb-gene-cluster rfbABCDX), and a recent rfbA-typing strategy for strain classification, we characterized the integrity and conservancy of the entire rfb operon in Bacteroidota. Through exploratory analysis of complete genomes and metagenomes, we discovered that most Bacteroidota have the rfb operon fragmented into nonrandom patterns of gene-singlets and doublets/triplets, termed 'rfb-gene-clusters', or rfb-'minioperons' if predicted as transcriptional. To reflect global operon integrity, contiguity, duplication, and fragmentation principles, we propose a six-category (infra/supra-numerary) cataloging system and a Global Operon Profiling System for bacteria. Mechanistically, genomic sequence analyses revealed that operon fragmentation is driven by intra-operon insertions of predominantly Bacteroides-DNA (thetaiotaomicron/fragilis) and likely natural selection in gut-wall specific micro-niches or micropathologies. Bacteroides-insertions, also detected in other antigenic operons (fimbriae), but not in operons deemed essential (ribosomal), could explain why Bacteroidota have fewer KEGG-pathways despite large genomes. DNA insertions, overrepresenting DNA-exchange-avid (Bacteroides) species, impact our interpretation of functional metagenomics data by inflating by inflating gene-based pathway inference and by overestimating 'extra-species' abundance. Of disease relevance, Bacteroidota species isolated from cavitating/cavernous fistulous tract (CavFT) microlesions in Crohn's Disease have supra-numerary fragmented operons, stimulate TNF-alpha from macrophages with low potency, and do not induce hyperacute peritonitis in mice compared to CavFT Enterobacteriaceae. The impact of 'foreign-DNA' insertions on pro-inflammatory operons, metagenomics, and commensalism/opportunism requires further studies to elucidate their potential for novel diagnostics and therapeutics, and to elucidate the role of co-existing pathobionts in Crohn's disease microlesions.

Do Bacterial Outer Membrane Vesicles Contribute to Chronic Inflammation in Parkinson's Disease?

Parkinson's disease (PD) is an increasingly common neurodegenerative disease. It has been suggested that the etiology of idiopathic PD is complex and multifactorial involving environmental contributions, such as viral or bacterial infections and microbial dysbiosis, in genetically predisposed individuals. With advances in our understanding of the gut-brain axis, there is increasing evidence that the intestinal microbiota and the mammalian immune system functionally interact. Recent findings suggest that a shift in the gut microbiome to a pro-inflammatory phenotype may play a role in PD onset and progression. While there are links between gut bacteria, inflammation, and PD, the bacterial products involved and how they traverse the gut lumen and distribute systemically to trigger inflammation are ill-defined. Mechanisms emerging in other research fields point to a role for small, inherently stable vesicles released by Gram-negative bacteria, called outer membrane vesicles in disease pathogenesis. These vesicles facilitate communication between bacteria and the host and can shuttle bacterial toxins and virulence factors around the body to elicit an immune response in local and distant organs. In this perspective article, we hypothesize a role for bacterial outer membrane vesicles in PD pathogenesis. We present evidence suggesting that these outer membrane vesicles specifically from Gram-negative bacteria could potentially contribute to PD by traversing the gut lumen to trigger local, systemic, and neuroinflammation. This perspective aims to facilitate a discussion on outer membrane vesicles in PD and encourage research in the area, with the goal of developing strategies for the prevention and treatment of the disease.

Flammulina velutipes polysaccharides regulate lipid metabolism disorders in HFD-fed mice via bile acids metabolism

Our recent study demonstrated that the dynamic changes of gut microbiota mediated by Flammulina velutipes polysaccharide (FVP) could effectively regulate the lipid metabolism in high fat diet-fed (HFD-fed) obese mice model. In this paper, further research was carried out by examining the bile acid (BAs) profiles, as well as the BAs metabolic pathways changes in obese mice. Furthermore, the regulatory effect of BAs on lipid metabolism was verified by 3 T3-L1 preadipocyte differentiation model. The FVP administration resulted in lower BAs content in plasma of obese mice. From the qRT-PCR analysis, FVP could relieve cholestasis in obese mice through altering the BAs metabolic pathways, changing the related genes expressions in mice liver and ileum. The cholic acid (CA), chenodeoxycholic acid (CDCA), hyodeoxycholic acid (HDCA) and ursodeoxycholic acid (UDCA) were selected in cell experiment which all reduced the intracellular triglyceride content and increased the expression of AMPKα1 in 3 T3-L1 adipocytes. Furthermore, CA and CDCA were found increased the expression of PPARα. In combination with our previous research, we further confirmed in this paper that the changes of BAs metabolism caused by FVP showed a positive effect on lipid metabolism, both in obese mice and 3 T3-L1 adipocytes.

Recent Advances in Chemical Synthesis of Structural Domains of Lipopolysaccharides from the Commensal Gut-Associated Microbiota

Lipopolysaccharides from the commensal gut-associated microbiota are interesting biomolecules for the treatment of various inflammatory diseases. Different from pathogenic lipopolysaccharides, commensal lipopolysaccharides have distinct chemical structures and mediate beneficial homeostasis with the immune system of the host. However, the accessibility issues of homogenous and pure commensal lipopolysaccharides hampered the in-depth studies of their functions. In this concept article, we highlight the recent synthesis of lipopolysaccharides from gut-associated lymphoid-tissue-resident Alcaligenes faecalis and Bacteroides vulgatus, which hopes to inspire the more efforts devoting to these fantastic biomolecules.

Modulation of Xiongdanjiuxin pills on the gut-liver axis in high-fat diet rats

AIM

Xiongdanjiuxin pill (XP) is a traditional Chinese medicine formula for the prevention and treatment of hyperlipidemia (HLP) and related complications. In this study, the gut-liver axis was used as the breakthrough point to analyze the therapeutic effect and potential mechanism of XP on HLP model rats and related complications.

MAIN METHODS

We used high-fat diet (HFD) to establish the HLP model of rats and treated them with XP. The 16S rRNA sequencing method was used to explore the effect of XP on the gut microbiota of HFD rats, and the effects of XP on ileum pathology, intestinal barrier and circulatory inflammation in HFD rats were also investigated. We further explored the molecular mechanism of XP treating liver inflammation in rats with HFD by regulating toll-like receptor 4 (TLR4) signaling.

KEY FINDINGS

We found that XP could regulate the imbalance of gut microbiota in HFD rats, and up-regulate the expression of tight junction protein in intestinal epithelium of HFD rats, thereby improving the intestinal barrier damage and intestinal inflammatory response. In addition, XP could significantly reduce the levels of inflammatory cytokines in HFD rats, and inhibit TLR4 signaling pathway, thereby reducing liver inflammation in HFD rats.

SIGNIFICANCE

XP can effectively improve the imbalance of gut-liver axis in hyperlipidemic rats and alleviate the inflammatory damage of liver. Its mechanism may be related to regulating the disorder of gut microbiota and inhibiting TLR4 signal pathway, so as to achieve the therapeutic effect on hyperlipidemic fatty liver in rats.

Emerging nanotherapeutic strategies targeting gut-X axis against diseases

Gut microbiota can coordinate with different tissues and organs to maintain human health, which derives the concept of the gut-X axis. Conversely, the dysbiosis of gut microbiota leads to the occurrence and development of various diseases, such as neurological diseases, liver diseases, and even cancers. Therefore, the modulation of gut microbiota offers new opportunities in the field of medicines. Antibiotics, probiotics or other treatments might restore unbalanced gut microbiota, which effects do not match what people have expected. Recently, nanomedicines with the high targeting ability and reduced toxicity make them an appreciative choice for relieving disease through targeting gut-X axis. Considering this paradigm-setting trend, the current review summarizes the advancements in gut microbiota and its related nanomedicines. Specifically, this article introduces the immunological effects of gut microbiota, summarizes the gut-X axis-associated diseases, and highlights the nanotherapeutics-mediated treatment via remolding the gut-X axis. Moreover, this review also discusses the challenges in studies related to nanomedicines targeting the gut microbiota and offers the future perspective, thereby aiming at charting a course toward clinic.

Immunogenic molecules associated with gut bacterial cell walls: chemical structures, immune-modulating functions, and mechanisms

Interactions between gut microbiome and host immune system are fundamental to maintaining the intestinal mucosal barrier and homeostasis. At the host-gut microbiome interface, cell wall-derived molecules from gut commensal bacteria have been reported to play a pivotal role in training and remodeling host immune responses. In this article, we review gut bacterial cell wall-derived molecules with characterized chemical structures, including peptidoglycan and lipid-related molecules that impact host health and disease processes via regulating innate and adaptive immunity. Also, we aim to discuss the structures, immune responses, and underlying mechanisms of these immunogenic molecules. Based on current advances, we propose cell wall-derived components as important sources of medicinal agents for the treatment of infection and immune diseases.

The chemistry of gut microbiome-derived lipopolysaccharides impacts on the occurrence of food allergy in the pediatric age

Introduction: Food allergy (FA) in children is a major health concern. A better definition of the pathogenesis of the disease could facilitate effective preventive and therapeutic measures. Gut microbiome alterations could modulate the occurrence of FA, although the mechanisms involved in this phenomenon are poorly characterized. Gut bacteria release signaling byproducts from their cell wall, such as lipopolysaccharides (LPSs), which can act locally and systemically, modulating the immune system function. Methods: In the current study gut microbiome-derived LPS isolated from fecal samples of FA and healthy children was chemically characterized providing insights into the carbohydrate and lipid composition as well as into the LPS macromolecular nature. In addition, by means of a chemical/MALDI-TOF MS and MS/MS approach we elucidated the gut microbiome-derived lipid A mass spectral profile directly on fecal samples. Finally, we evaluated the pro-allergic and pro-tolerogenic potential of these fecal LPS and lipid A by harnessing peripheral blood mononuclear cells from healthy donors. Results: By analyzing fecal samples, we have identified different gut microbiome-derived LPS chemical features comparing FA children and healthy controls. We also have provided evidence on a different immunoregulatory action elicited by LPS on peripheral blood mononuclear cells collected from healthy donors suggesting that LPS from healthy individuals could be able to protect against the occurrence of FA, while LPS from children affected by FA could promote the allergic response. Discussion: Altogether these data highlight the relevance of gut microbiome-derived LPSs as potential biomarkers for FA and as a target of intervention to limit the disease burden.

Contribution of gut microbiota to drug-induced liver injury

Drug-induced liver injury (DILI) is caused by various drugs with complex pathogenesis, and diverse clinical and pathological phenotypes. Drugs damage the liver directly through drug hepatotoxicity, or indirectly through drug-mediated oxidative stress, immune injury and inflammatory insult, which eventually lead to hepatocyte necrosis. Recent studies have found that the composition, relative content and distribution of gut microbiota in patients and animal models of DILI have changed significantly. It has been confirmed that gut microbial dysbiosis brings about intestinal barrier destruction and microorganisms translocation, and the alteration of microbial metabolites may cause or aggravate DILI. In addition, antibiotics, probiotics, and fecal microbiota transplantation are all emerging as prospective therapeutic methods for DILI by regulating the gut microbiota. In this review, we discussed how the altered gut microbiota participates in DILI.

Interactions between gut microbiota and polyphenols: A mechanistic and metabolomic review

BACKGROUND

Polyphenols are a class of naturally sourced compounds with widespread distribution and an extensive array of bioactivities. However, due to their complex constituents and weak absorption, a convincing explanation for their remarkable bioactivity remains elusive for a long time. In recent years, interaction with gut microbiota is hypothesized to be a reasonable explanation of the potential mechanisms for natural compounds especially polyphenols.

OBJECTIVES

This review aims to present a persuasive explanation for the contradiction between the limited bioavailability and the remarkable bioactivities of polyphenols by examining their interactions with gut microbiota.

METHODS

We assessed literatures published before April 10, 2023, from several databases, including Scopus, PubMed, Google Scholar, and Web of Science. The keywords used include "polyphenols", "gut microbiota", "short-chain fatty acids", "bile acids", "trimethylamine N-oxide", "lipopolysaccharides" "tryptophan", "dopamine", "intestinal barrier", "central nervous system", "lung", "anthocyanin", "proanthocyanidin", "baicalein", "caffeic acid", "curcumin", "epigallocatechin-3-gallate", "ferulic acid", "genistein", "kaempferol", "luteolin", "myricetin", "naringenin", "procyanidins", "protocatechuic acid", "pterostilbene", "quercetin", "resveratrol", etc. RESULTS: The review first demonstrates that polyphenols significantly alter gut microbiota diversity (α- and β-diversity) and the abundance of specific microorganisms. Polyphenols either promote or inhibit microorganisms, with various factors influencing their effects, such as dosage, treatment duration, and chemical structure of polyphenols. Furthermore, the review reveals that polyphenols regulate several gut microbiota metabolites, including short-chain fatty acids, dopamine, trimethylamine N-oxide, bile acids, and lipopolysaccharides. Polyphenols affect these metabolites by altering gut microbiota composition, modifying microbial enzyme activity, and other potential mechanisms. The changed microbial metabolites induced by polyphenols subsequently trigger host responses in various ways, such as acting as intestinal acid-base homeostasis regulators and activating on specific target receptors. Additionally, polyphenols are transformed into microbial derivatives by gut microbiota and these polyphenols' microbial derivatives have many potential advantages (e.g., increased bioactivity, improved absorption). Lastly, the review shows polyphenols maintain intestinal barrier, central nervous system, and lung function homeostasis by regulating gut microbiota.

CONCLUSION

The interaction between polyphenols and gut microbiota provides a credible explanation for the exceptional bioactivities of polyphenols. This review aids our understanding of the underlying mechanisms behind the bioactivity of polyphenols.

The transcriptome sequencing analysis reveals immune mechanisms of soybean fermented powder on the loach (Misgurnus anguillicaudatus) in response to Lipopolysaccharide (LPS) infection

The loach (Misgurnus anguillicaudatus), a small commercial fish that is widely cultivated for its high-quality protein, vitamins, minerals, and essential amino acid, is a member of the genus Misgurnus and the family Cyprinidae. In this study, we gave the LPS-injected loach fermented soybean meal and used transcriptome sequencing to investigate the impact of the fermented soybean powder on the loach's immune system. 3384 up-regulated genes and 12116 down-regulated genes were found among the 15500 differentially expressed genes, according to the results. The differentially expressed genes were shown to be involved in cellular processes, metabolic processes, cellular anatomical entities, and binding, according to the Go functional annotation. Meanwhile, the KEGG enrichment analysis indicated that the soybean fermented powder treated groups showed significant differences in DNA replication, Nucleotide excision repair, Fanconi anemia pathway, and Base excision repair pathways, suggesting that these pathways are closely related to the enhancement of the immune function of loach by soybean fermented powder. The particular conclusions not exclusively can provide a new conception for the rational utilization of soybean fermented powder but also can provide theoretical guidance for the subsequent healthy breeding of loach.

Immunochemical studies and gene cluster relationships of closely related O-antigens of Aeromonas hydrophila Pt679, Aeromonas popoffii A4, and Aeromonas sobria K928 strains classified into the PGO1 serogroup dominant in Polish aquaculture of carp and rainbow trout

The present study included three Aeromonas sp. strains isolated from fish tissues during Motile Aeromonas Infection/Motile Aeromonas Septicaemia disease outbreaks on commercial farms, i.e.: Aeromonas hydrophila Pt679 obtained from rainbow trout as well as Aeromonas popoffii A4 (formerly Aeromonas encheleia) and Aeromonas sobria K928 both isolated from carp, which were classified into the new provisional PGO1 serogroup prevailing among aeromonads in Polish aquaculture. The structure of the O-specific polysaccharides of A4 and K928 has been previously established. Here, immunochemical studies of the O-specific polysaccharide of A. hydrophila Pt679 were undertaken. The O-specific polysaccharide was obtained from the lipopolysaccharide of A. hydrophila Pt679 after mild acid hydrolysis and separation by gel-permeation chromatography. The high-molecular-mass fraction was studied using chemical methods and ¹H and ¹³C NMR spectroscopy, including ¹H,¹H NOESY, and ¹H,¹³C HMBC experiments. The following structure of the branched repeating unit of the O-polysaccharide from A. hydrophila Pt679 was determined: [Formula: see text] The studies indicated that O-polysaccharides from A. hydrophila Pt679, A. popoffii A4 and A. sobria K928 share similarities but they also contain unique characteristics. Western blotting and an enzyme-linked immunosorbent assay revealed that the cross-reactivity of the related O-antigens is caused by the occurrence of common structural elements, whereas additional epitopes define the specificity of the O-serotypes. For genetic relationship studies, the O-antigen gene cluster was characterized in the genome of the A. hydrophila Pt679 strain and compared with the corresponding sequences of A. popoffii A4 and A. sobria K928 and with sequences available in the databases. The composition of the regions was found to be consistent with the O-antigen structures of Aeromonas strains classified into the same PGO1 serogroup.

The basis of antigenic operon fragmentation in Bacteroidota and commensalism

The causes for variability of pro-inflammatory surface antigens that affect gut commensal/opportunistic dualism within the phylum Bacteroidota remain unclear (1, 2). Using the classical lipopolysaccharide/O-antigen 'rfb operon' in Enterobacteriaceae as a surface antigen model (5-gene-cluster rfbABCDX), and a recent rfbA-typing strategy for strain classification (3), we characterized the architecture/conservancy of the entire rfb operon in Bacteroidota. Analyzing complete genomes, we discovered that most Bacteroidota have the rfb operon fragmented into non-random gene-singlets and/or doublets/triplets, termed 'minioperons'. To reflect global operon integrity, duplication, and fragmentation principles, we propose a five-category (infra/supernumerary) cataloguing system and a Global Operon Profiling System for bacteria. Mechanistically, genomic sequence analyses revealed that operon fragmentation is driven by intra-operon insertions of predominantly Bacteroides-DNA (thetaiotaomicron/fragilis) and likely natural selection in specific micro-niches. Bacteroides-insertions, also detected in other antigenic operons (fimbriae), but not in operons deemed essential (ribosomal), could explain why Bacteroidota have fewer KEGG-pathways despite large genomes (4). DNA insertions overrepresenting DNA-exchange-avid species, impact functional metagenomics by inflating gene-based pathway inference and overestimating 'extra-species' abundance. Using bacteria from inflammatory gut-wall cavernous micro-tracts (CavFT) in Crohn's Disease (5), we illustrate that bacteria with supernumerary-fragmented operons cannot produce O-antigen, and that commensal/CavFT Bacteroidota stimulate macrophages with lower potency than Enterobacteriaceae, and do not induce peritonitis in mice. The impact of 'foreign-DNA' insertions on pro-inflammatory operons, metagenomics, and commensalism offers potential for novel diagnostics and therapeutics.

Association between lipid-A-producing oral bacteria of different potency and fractional exhaled nitric oxide in a Norwegian population-based adult cohort

BACKGROUND

Lipid A is the primary immunostimulatory part of the lipopolysaccharide (LPS) molecule. The inflammatory response of LPS varies and depends upon the number of acyl chains and phosphate groups in lipid A which is specific for a bacterial species or strain. Traditional LPS quantification assays cannot distinguish between the acylation degree of lipid A molecules, and therefore little is known about how bacteria with different inflammation-inducing potencies affect fractional exhaled nitric oxide (F_eNO). We aimed to explore the association between pro-inflammatory hexa- and less inflammatory penta-acylated LPS-producing oral bacteria and F_eNO as a marker of airway inflammation.

METHODS

We used data from a population-based adult cohort from Norway (n = 477), a study center of the RHINESSA multi-center generation study. We applied statistical methods on the bacterial community- (prediction with MiRKAT) and genus-level (differential abundance analysis with ANCOM-BC) to investigate the association between the oral microbiota composition and F_eNO.

RESULTS

We found the overall composition to be significantly associated with increasing F_eNO levels independent of covariate adjustment, and abundances of 27 bacterial genera to differ in individuals with high F_eNO vs. low F_eNO levels. Hexa- and penta-acylated LPS producers made up 2.4% and 40.8% of the oral bacterial genera, respectively. The Bray-Curtis dissimilarity within hexa- and penta-acylated LPS-producing oral bacteria was associated with increasing F_eNO levels independent of covariate adjustment. A few single penta-acylated LPS producers were more abundant in individuals with low F_eNO vs. high F_eNO, while hexa-acylated LPS producers were found not to be enriched.

CONCLUSIONS

In a population-based adult cohort, F_eNO was observed to be associated with the overall oral bacterial community composition. The effect of hexa- and penta-acylated LPS-producing oral bacteria was overall significant when focusing on Bray-Curtis dissimilarity within each of the two communities and F_eNO levels, but only penta-acylated LPS producers appeared to be reduced or absent in individuals with high F_eNO. It is likely that the pro-inflammatory effect of hexa-acylated LPS producers is counteracted by the dominance of the more abundant penta-acylated LPS producers in this population-based adult cohort involving mainly healthy individuals.

Bacillus amyloliquefaciens alleviates the pathological injuries in mice infected with Schistosoma japonicum by modulating intestinal microbiome

Schistosoma japonicum causes serious pathological organ damage and alteration of the intestinal microbiome in the mammalian host, threatening the health of millions of people in China. Bacillus amyloliquefaciens has been reported to be able to alleviate the damage to the gut and liver and maintain the homeostasis of the intestinal microenvironment. However, it was unclear whether B. amyloliquefaciens could alleviate the hepatic and intestinal symptoms caused by S. japonicum. In this study, the intragastric administration of B. amyloliquefaciens was performed to treat S. japonicum-infected mice during the acute phase. Histopathological analysis and 16S rRNA gene sequencing were used to evaluate the pathological damage and changes in the intestinal microbiome. The results of the study showed that B. amyloliquefaciens treatment significantly reduced the degree of granuloma and fibrosis in infected mice. Additionally, recovery of diversity in the intestinal microbiome, decrease in the relative abundance of potential pathogenic bacteria such as Escherichia-Shigella, and reshaping of the interactive network between genera in the intestine were also observed after treatment with B. amyloliquefaciens. Our findings indicated that treatment with B. amyloliquefaciens effectively alleviated the pathological injuries of the liver and intestine in mice infected with S. japonicum by modulating the intestinal microbiome, implying that this probiotic can function as an effective therapeutic agent against schistosomiasis. We hope our study will provide auxiliary strategies and methods for the early prevention of schistosomiasis japonica.

Lactiplantibacillus plantarum NKK20 Alleviates High-Fat-Diet-Induced Nonalcoholic Fatty Liver Disease in Mice through Regulating Bile Acid Anabolism

Nonalcoholic fatty liver disease (NAFLD) is the most prevalent chronic disease in modern society. It is characterized by an accumulation of lipids in the liver and an excessive inflammatory response. Clinical trials have provided evidence that probiotics may prevent the onset and relapse of NAFLD. The aim of this study was to explore the effect of Lactiplantibacillus plantarum NKK20 strain (NKK20) on high-fat-diet-induced NAFLD in an ICR murine model and propose the underlying mechanism whereby NKK20 protects against NAFLD. The results showed that the administration of NKK20 ameliorated hepatocyte fatty degeneration, reduced total cholesterol and triglyceride concentrations, and alleviated inflammatory reactions in NAFLD mice. In addition, the 16S rRNA sequencing results indicated that NKK20 could decrease the abundance of Pseudomonas and Turicibacter and increase the abundance of Akkermansia in NAFLD mice. LC-MS/MS analysis showed that NKK20 could significantly increase the concentration of short-chain fatty acids (SCFAs) in the colon contents of mice. The obtained non-targeted metabolomics results revealed a significant difference between the metabolites in the colon contents of the NKK20 administration group and those in the high-fat diet group, in which a total of 11 different metabolites that were significantly affected by NKK20 were observed, and these metabolites were mainly involved in bile acid anabolism. UPLC-MS technical analysis revealed that NKK20 could change the concentrations of six conjugated and free bile acids in mouse liver. After being treated with NKK20, the concentrations of cholic acid, glycinocholic acid, and glycinodeoxycholic acid in livers of the NAFLD mice were significantly decreased, while the concentration of aminodeoxycholic acid was significantly increased. Thus, our findings indicate that NKK20 can regulate bile acid anabolism and promote the production of SCFA, which can inhibit inflammation and liver damage and thus prevent the development of NAFLD.

Therapeutic possibilities of gut microbiota modulation in acute decompensation of liver cirrhosis

The formation of liver cirrhosis (LC) is an unfavorable event in the natural history of chronic liver diseases and with the development of portal hypertension and/or impaired liver function can cause a fatal outcome. Decompensation of LC is considered the most important stratification variable for the risk of death. It is currently postulated that decompensation of LC occurs through an acute (including acute-on-chronic liver failure) and non-acute pathway. Acute decompensation of LC is accompanied by the development of life-threatening complications, characterized by an unfavorable prognosis and high mortality. Progress in understanding the underlying molecular mechanisms has led to the search for new interventions, drugs, and biological substances that can affect key links in the pathogenesis of acute decompensation in LC, for example the impaired gut-liver axis and associated systemic inflammation. Given that particular alterations in the composition and function of gut microbiota play a crucial role here, the study of the therapeutic possibilities of its modulation has emerged as one of the top concerns in modern hepatology. This review summarized the investigations that describe the theoretical foundations and therapeutic potential of gut microbiota modulation in acute decompensation of LC. Despite the encouraging preliminary data, the majority of the suggested strategies have only been tested in animal models or in preliminary clinical trials; additional multicenter randomized controlled trials must demonstrate their efficacy in larger patient populations.

Assessment of Nonalcoholic Fatty Liver Disease Symptoms and Gut-Liver Axis Status in Zebrafish after Exposure to Polystyrene Microplastics and Oxytetracycline, Alone and in Combination

BACKGROUND

Environmental pollution may give rise to the incidence and progression of nonalcoholic fatty liver disease (NAFLD), the most common cause for chronic severe liver lesions. Although knowledge of NAFLD pathogenesis is particularly important for the development of effective prevention, the relationship between NAFLD occurrence and exposure to emerging pollutants, such as microplastics (MPs) and antibiotic residues, awaits assessment.

OBJECTIVES

This study aimed to evaluate the toxicity of MPs and antibiotic residues related to NAFLD occurrence using the zebrafish model species.

METHODS

Taking common polystyrene MPs and oxytetracycline (OTC) as representatives, typical NAFLD symptoms, including lipid accumulation, liver inflammation, and hepatic oxidative stress, were screened after 28-d exposure to environmentally realistic concentrations of MPs (0.69mg/L) and antibiotic residue (3.00μg/L). The impacts of MPs and OTC on gut health, the gut-liver axis, and hepatic lipid metabolism were also investigated to reveal potential affecting mechanisms underpinning the NAFLD symptoms observed.

RESULTS

Compared with the control fish, zebrafish exposed to MPs and OTC exhibited significantly higher levels of lipid accumulation, triglycerides, and cholesterol contents, as well as inflammation, in conjunction with oxidative stress in their livers. In addition, a markedly smaller proportion of Proteobacteria and higher ratios of Firmicutes/Bacteroidetes were detected by microbiome analysis of gut contents in treated samples. After the exposures, the zebrafish also experienced intestinal oxidative injury and yielded significantly fewer numbers of goblet cells. Markedly higher levels of the intestinal bacteria-sourced endotoxin lipopolysaccharide (LPS) were also detected in serum. Animals treated with MPs and OTC exhibited higher expression levels of LPS binding receptor (LBP) and downstream inflammation-related genes while also exhibiting lower activity and gene expression of lipase. Furthermore, MP-OTC coexposure generally exerted more severe effects compared with single MP or OTC exposure.

DISCUSSION

Our results suggested that exposure to MPs and OTC may disrupt the gut-liver axis and be associated with NAFLD occurrence. https://doi.org/10.1289/EHP11600.

Bacterial lipopolysaccharide with different administration routes affects intestinal mucosal morphological, immunological, and microbial barrier functions in goslings

The current study was conducted to evaluate the effects of different administration routes of bacterial lipopolysaccharide (LPS) on intestinal mucosal morphological, immunological, and microbial barrier functions in goslings. First, we compared intestinal villi morphology of goslings under intraperitoneal or oral LPS treatment through hematoxylin and eosin staining. Then, we determined the signatures of the microbiome in the ileum mucosa of goslings subjected to oral LPS treatment at 0, 2, 4, and 8 mg/kg BW by 16S sequencing, and analyzed the changes in intestinal barrier functions and permeability, levels of LPS in the ileum mucosa, plasma, and liver tissue, and the induced inflammatory response of Toll-like receptor 4 (TLR4). As a result, intraperitoneal LPS injection resulted in a thicker intestinal wall in the ileum within a short time, whereas villus height was less affected; in contrast, oral LPS treatment exerted a stronger influence on villus height but not on intestinal wall thickness. We also found that oral LPS treatment affected the structure of the intestinal microbiome, reflected by changes in the clustering of intestinal microbiota. The average abundance of Muribaculaceae showed an increasing trend with increasing LPS levels, and that of the genus Bacteroides decreased, compared with the control group. In addition, oral LPS treatment with 8 mg/kg BW affected the intestinal epithelial morphology, damage the mucosal immune barrier, downregulated the expression of tight junction proteins, increased circulating D-lactate levels, and stimulated the secretion of various inflammatory mediators and activation of the TLR4/MyD88/NFκB pathway. This study presented the injuries of intestinal mucosal barrier function induced by LPS challenges in goslings and provided a scientific model for searching the novel strategies to attenuate the immunological stress and gut injury caused by LPS.

DHA-enriched phosphatidylserine alleviates high fat diet-induced jejunum injury in mice by modulating gut microbiota

A long-term high-fat diet (HFD) is one of the high-risk factors for intestinal barrier damage. Docosahexaenoic acid-enriched phosphatidylserine (DHA-PS) has multiple biological activities, while its protective effect on HFD-caused jejunum injury remains unknown. Thus, the present study investigated the protective effect of DHA-PS on HFD-induced jejunum injury in mice. Our results showed that DHA-PS (100 mg per kg per d) could protect against HFD-caused jejunum injury by decreasing the levels of inflammatory factors such as interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α) in the serum and jejunum tissues, with histological analysis confirming this injury amelioration. Additionally, DHA-PS alleviated the HFD-caused oxidative stress by decreasing malondialdehyde (MDA) and increasing total antioxidant capacity (T-AOC), superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) levels in the jejunum. Moreover, DHA-PS significantly increased the expression of tight junction proteins (ZO-1, occludin, and claudin-4) in the jejunum, and modulated the HFD-induced gut microbiota disorder by decreasing the Firmicutes and Bacteroidetes ratio, and reducing the relative abundance of Lachnoclostridium, Coriobacteriaceae, Desulfovibrionaceae, and Helicobacter, while increasing the relative abundance of Lachnospiraceae_NK4A136_group, Alistipes, norank_f__Muribaculaceae, and Bacteroides. Overall, these results support that DHA-PS can alleviate the HFD-caused jejunum injury.

Thyme (Thymus vulgaris L.) polyphenols ameliorate DSS-induced ulcerative colitis of mice by mitigating intestinal barrier damage, regulating gut microbiota, and suppressing TLR4/NF-κB-NLRP3 inflammasome pathways

Thyme (Thymus vulgaris L.) is an important medicinal and edible homologous plant, and the composition and bioactivity of its polyphenol extracts have attracted widespread attention from researchers. In this study, the polyphenols in thyme were separated and identified by UPLC/MS-MS and UPLC-DAD, and the intervention effect and mechanism of thyme polyphenols (TP) on ulcerative colitis (UC) were analyzed in combination with dextran sulfate sodium salt (DSS)-induced mice colitis model. It was found that the main substances of TP were scutellarin (160.68 ± 2.09 mg g^-1), rosmarinic acid (80.33 ± 1.74 mg g^-1), scutellarein (56.53 ± 1.32 mg g^-1), apigenin-7-O-glucuronide (21.06 ± 0.68 mg g^-1), gallic acid (13.80 ± 0.73 mg g^-1), and ferulic acid (12.00 ± 0.20 mg g^-1). TP and sulfasalazine, which were respectively supplemented to these experimental mice at 200 mg per kg bw and 100 mg per kg bw, showed similar effects on alleviating intestinal inflammation, as indicated by the consistency of the decreased NLRP3 and TLR4 proteins and inhibited pro-inflammatory cytokine secretion in NF-κB inflammatory signaling pathway. Furthermore, the treatment with TP at doses of 200 and 400 mg per kg bw both effectively upregulated tight junction protein expression and enhanced intestinal epithelial cell integrity. Consistently, the abundany of probiotics including Blautia, Bacteroides, Romboutsia, and Faecalibaculum associated with the synthesis of short chain fatty acids (SCFAs) were elevated, whereas harmful bacteria including Escherichia Shigella, Muribaculum, and Clostridium sensu stricto 1 associated with the inflammatory process were significantly inhibited. Notably, TP supplemented at the dose of 100 mg per kg bw showed weak mitigated effects on the above symptoms, while the other two TP experimental groups showed similar promising therapeutic potential, suggesting that such beneficial effects required a certain dose of TP to be achieved. These results indicated that TP could suppress the TLR4/NLRP3-NF-κB inflammasome pathways, protect the intestinal epithelial barrier, and remodel the disordered gut microbiota, which suggested that TP might be a promising dietary strategy for UC.

Mechanisms of Toll-like receptor tolerance induced by microbial ligands

Some microorganisms can develop tolerance. On the one hand, it allows pathogenic microbes to escape immune surveillance, on the other hand, it provides the possibility to microbiota representatives to colonize different biotopes and build a symbiotic relationship with the host. Complex regulatory interactions between innate and adaptive immune systems as well as stimulation by antigens help microbes control and maintain immunological tolerance. An important role in this process belongs to innate immune cells, which recognize microbial components through pattern-recognition receptors. Toll-like receptors (TLRs) represent the main class of these receptors. Despite the universality of the activated signaling pathways, different cellular responses are induced by interaction of TLRs with microbiota representatives and pathogenic microbes, and they vary during acute and chronic infection. The research on mechanisms underlying the development of TLR tolerance is significant, as the above receptors are involved in a wide range of infectious and noninfectious diseases; they also play an important role in development of allergic diseases, autoimmune diseases, and cancers. The knowledge of TLR tolerance mechanisms can be critically important for development of TLR ligand-based therapeutic agents for treatment and prevention of multiple diseases.

Extraction, Purification, and Chemical Degradation of LPS from Gut Microbiota Strains

It is estimated that more than 500 different bacterial species colonize the human gut, and they are collectively known as the gut microbiota. Such a massive bacterial presence is now considered an additional organ of the human body, thus becoming the object of an intense and daily growing research activity. Gram-negative bacteria represent a large percentage of the gut microbiota strains. The main constituent of the outer membrane of Gram-negatives is the lipopolysaccharide (LPS). Since its first discovery, LPS has been extensively studied for its structure-dependent capability to elicit a potent immune inflammatory reaction when perceived by specific immune receptors present in our body. Therefore, traditionally, LPS, due to its peculiar chemistry, has been associated with pathogenic bacteria, and it has been extensively studied for its dangerous effects on human health. However, LPS is also expressed on the cell surface of harmless and beneficial bacteria that colonize our intestines. This necessarily implies that the LPS from harmless gut microbes is "chemically different" from that owned by pathogenic ones, hence enabling successful colonization of the intestinal tract without creating a threat to the host immune system. Deciphering the structural features of LPS from these gut bacteria is essential to improve our still scarce knowledge of how the human host lives in a harmonious relationship with its own microbiota. To this end, LPS extraction and purification are essential steps in this field of research. Yet working with gut bacteria is extremely complex for a number of reasons, one being related to the fact that they produce an array of other glycans and glycoconjugates, such as capsular polysaccharides and/or exopolysaccharides, which render the isolation and characterization of the sole LPS not at all trivial. Here, we provide a protocol that might help when dealing with LPS from gut microbial species. We describe the preliminary manipulations and checks, extraction, and purification approaches, as well as the necessary chemical manipulations that should be performed to enable the characterization of the structure of an LPS by means of techniques like nuclear magnetic resonance spectroscopy and mass spectrometry.

Flos Puerariae-Semen Hoveniae medicinal pair extract ameliorates DSS-induced inflammatory bowel disease through regulating MAPK signaling and modulating gut microbiota composition

Background: Inflammatory bowel disease (IBD) is a global gastrointestinal disease characterized by relapsing and remitting inflammatory conditions. Flos Puerariae (the flower of Pueraria lobata [Willd.] Ohwi and P. thomsonii Benth.) and Hovenia dulcis Thunb. (Rhamnaceae) are traditional Chinese medicines. This medicinal pair has been used to treat various diseases due to its excellent anti-oxidant and anti-inflammatory activity. However, the effects of extracts from these plants on dextran sulfate sodium (DSS)-induced colitis have not been investigated; further study is needed to improve the understanding of their mechanisms of action and potential applications. Methods: The chemical constitution of extracts from Flos Puerariae and Semen Hoveniae (PHE) was analyzed using UPLC-LTQ-Orbitrap-MS/MS. The protective effects of PHE on mice with DSS-induced colitis were evaluated through assessment of body weight loss, disease activity index (DAI) score, colon length shortening, and pathological changes. The levels of inflammatory cytokines were determined by ELISA and RT-qPCR. Biomarkers of oxidative stress (ROS, CAT, SOD, MDA, and T-AOC) were analyzed using biochemical kits. The expression of MAPK proteins was determined by Western blotting analysis. Gut microbiota were analyzed via 16S rRNA sequencing. Results: Chemical composition analysis indicated that PHE contains various bioactive compounds, including puerarin, kakkalide, tectoridin, and genistin. The findings from this study suggest that PHE could effectively modulate histopathological score, inflammatory cell infiltration, and inflammatory factor secretion. Notably, PHE ameliorated oxidative stress by inhibiting activation of the MAPK pathway, leading to decreased inflammatory mediators and restored antioxidant enzyme activity. Furthermore, PHE treatment regulated the composition of the gut microbiota by increasing the abundance of benign bacteria, such as Akkermansia, and reducing the abundance of harmful bacteria, such as Proteobacteria. Conclusion: The findings from this study demonstrate the mechanism underlying the amelioration of DSS-induced intestinal oxidative stress by PHE and its positive impact on the restoration of the composition of gut microbiota.

Dietary Nutritional Level Affects Intestinal Microbiota and Health of Goats

The intestine is a complex micro-ecosystem, and its stability determines the health of animals. Different dietary nutritional levels affect the intestinal microbiota and health. In this study, the nutritional levels of energy and protein in the diet of goats were changed, and the body weight was measured every 15 days. In the late feeding period, 16 S rRNA sequencing technology was used to detect the content of microorganisms. A meteorological chromatograph was used to detect volatile fatty acids in the cecum and colon of goats. In the feeding stage, reducing the nutritional level of the diet significantly reduced the weight of the lamb (p < 0.05). In the cecum, the abundance of potentially harmful bacteria, such as Sphingomonas, Marvinbryantia, and Eisenbergiella, were significantly enriched in goats fed with the standard nutritional level diets (p < 0.05). Additionally, the contents of acetate (p = 0.037) and total VFAs (p = 0.041) increased. In the colon, the abundance of SCFAs-producing bacteria, such as Ruminococcaceae, Christensenellaceae, and Papillibacter, decreased as the nutritional level in the diet increased (p < 0.05). In conclusion, the increase in nutritional level could affect the growth performance and composition of intestinal microbiota.

The lung microbiome, peripheral gene expression, and recurrence-free survival after resection of stage II non-small cell lung cancer

BACKGROUND

Cancer recurrence after tumor resection in early-stage non-small cell lung cancer (NSCLC) is common, yet difficult to predict. The lung microbiota and systemic immunity may be important modulators of risk for lung cancer recurrence, yet biomarkers from the lung microbiome and peripheral immune environment are understudied. Such markers may hold promise for prediction as well as improved etiologic understanding of lung cancer recurrence.

METHODS

In tumor and distant normal lung samples from 46 stage II NSCLC patients with curative resection (39 tumor samples, 41 normal lung samples), we conducted 16S rRNA gene sequencing. We also measured peripheral blood immune gene expression with nanoString®. We examined associations of lung microbiota and peripheral gene expression with recurrence-free survival (RFS) and disease-free survival (DFS) using 500 × 10-fold cross-validated elastic-net penalized Cox regression, and examined predictive accuracy using time-dependent receiver operating characteristic (ROC) curves.

RESULTS

Over a median of 4.8 years of follow-up (range 0.2-12.2 years), 43% of patients experienced a recurrence, and 50% died. In normal lung tissue, a higher abundance of classes Bacteroidia and Clostridia, and orders Bacteroidales and Clostridiales, were associated with worse RFS, while a higher abundance of classes Alphaproteobacteria and Betaproteobacteria, and orders Burkholderiales and Neisseriales, were associated with better RFS. In tumor tissue, a higher abundance of orders Actinomycetales and Pseudomonadales were associated with worse DFS. Among these taxa, normal lung Clostridiales and Bacteroidales were also related to worse survival in a previous small pilot study and an additional independent validation cohort. In peripheral blood, higher expression of genes TAP1, TAPBP, CSF2RB, and IFITM2 were associated with better DFS. Analysis of ROC curves revealed that lung microbiome and peripheral gene expression biomarkers provided significant additional recurrence risk discrimination over standard demographic and clinical covariates, with microbiome biomarkers contributing more to short-term (1-year) prediction and gene biomarkers contributing to longer-term (2-5-year) prediction.

CONCLUSIONS

We identified compelling biomarkers in under-explored data types, the lung microbiome, and peripheral blood gene expression, which may improve risk prediction of recurrence in early-stage NSCLC patients. These findings will require validation in a larger cohort.

Evaluation of a Novel Synthetic Peptide Derived from Cytolytic Mycotoxin Candidalysin

The importance of neuroinflammation in neurology is becoming increasingly apparent. In addition to neuroinflammatory diseases such as multiple sclerosis, the role of neuroinflammation has been identified in many non-inflammatory neurological disorders such as stroke, epilepsy, and cancer. The immune response within the brain involves the presence of CNS resident cells; mainly glial cells, such as microglia, the CNS resident macrophages. We evaluated the peptide Ca-MAP1 bioinspired on the C. albicans immature cytolytic toxin candidalysin to develop a less hemolytic peptide with anti-neuroinflammatory, antibacterial, and cytotoxic activity against tumor cells. In silico and in vitro studies were performed at various concentrations. Ca-MAP1 exhibits low hemolytic activity at lower concentrations and was not cytotoxic to MRC-5 and BV-2 cells. Ca-MAP1 showed activity against Acinetobacter baumannii, Escherichia coli ATCC, E. coli KPC, Klebsiella pneumoniae ATCC, Pseudomonas aeruginosa, and Staphylococcus aureus ATCC. Furthermore, Ca-MAP1 exhibits anti-neuroinflammatory activity in the BV-2 microglia model, with 93.78% inhibition of nitrate production at 18.1 µM. Ca-MAP1 presents cytotoxic activity against tumor cell line NCI-H292 at 36.3 μM, with an IC₅₀ of 38.4 µM. Ca-MAP1 demonstrates results that qualify it to be evaluated in the next steps to promote the control of infections and provide an alternative antitumor therapy.

In vivo evidence of the prevents DSS-induced colitis of Lactiplantibacillus plantarum L15

Ulcerative colitis (UC) is challenging to treat and severely impacts patients and families. A previous study reported immunomodulatory and reduction of pro-inflammatory properties for the Lactiplantibacillus plantarum L15. This study aimed to analyze the preventive properties and mechanistic actions in an in vivo colitis model. The histopathological alteration, inflammation cytokines, and intestinal barrier function were analyzed. Subsequently, the cecal gut microbiota contents and products from different groups were detected. Finally, gene expressions related to the NF-κB signaling process were evaluated. L. plantarum L15 significantly decreased disease activity index (DAI), myeloperoxidase activity (MPO), pro-inflammatory cytokine (TNF-α, IL-1β, and IL-6) level, and increased weight change, colon length, and production of inflammation-suppressing cytokines. Furthermore, this strain supplementation substantially increased ZO-1, Occludin, and Claudin-1, and MUC2 mRNA expression levels with a corresponding decrease in serum lipopolysaccharide and D-lactic acid contents. In addition, L. plantarum L15 improved gut microbiota composition and increased short-chain fatty acid (SCFAs) in the colon content, which significantly reduced the transfer of NF-κB p65 to the nucleus. Our findings provide a theoretical basis for L. plantarum L15 as a preventive candidate for UC.

Bifidobacterium breve Alleviates DSS-Induced Colitis in Mice by Maintaining the Mucosal and Epithelial Barriers and Modulating Gut Microbes

This study was designed to explore the different intestinal barrier repair mechanisms of Bifidobacterium breve (B. breve) H4-2 and H9-3 with different exopolysaccharide (EPS) production in mice with colitis. The lipopolysaccharide (LPS)-induced IEC-6 cell inflammation model and dextran sulphate sodium (DSS)-induced mice colitis model were used. Histopathological changes, epithelial barrier integrity, short-chain fatty acid (SCFA) content, cytokine levels, NF-κB expression level, and intestinal flora were analyzed to evaluate the role of B. breve in alleviating colitis. Cell experiments indicated that both B. breve strains could regulate cytokine levels. In vivo experiments confirmed that oral administration of B. breve H4-2 and B. breve H9-3 significantly increased the expression of mucin, occludin, claudin-1, ZO-1, decreased the levels of IL-6, TNF-α, IL-1β and increased IL-10. Both strains of B. breve also inhibited the expression of the NF-κB signaling pathway. Moreover, B. breve H4-2 and H9-3 intervention significantly increased the levels of SCFAs, reduced the abundance of Proteobacteria and Bacteroidea, and increased the abundance of Muribaculaceae. These results demonstrate that EPS-producing B. breve strains H4-2 and H9-3 can regulate the physical, immune, and microbial barrier to repair the intestinal damage caused by DSS in mice. Of the two strains, H4-2 had a higher EPS output and was more effective at repair than H9-3. These results will provide insights useful for clinical applications and the development of probiotic products for the treatment of colitis.

Human gut microbiota composition and its predicted functional properties in people with western and healthy dietary patterns

PURPOSE

Some dietary habits cluster together, and for this reason it is advised to study the impact of entire dietary patterns on human health, rather than that of individual dietary habits. The main objective of this study was to evaluate differences in gut microbiota composition and their predicted functional properties between people with a healthy (HDP) and western (WDP) dietary pattern.

METHODS

A cross-sectional, observational study was carried out on 200 participants enrolled 2017-2018 in Poznań, Poland, equally distributed into HDP and WDP groups. Diet was estimated using 3-day food records and information on stool transit times was collected. Fecal microbiota composition was assessed by 16S rRNA gene sequencing and its functional properties were predicted by the PICRUSt2 workflow.

RESULTS

The α-diversity did not differ between people with WDP and HDP, but β-diversity was associated with dietary pattern. People with HDP had higher relative abundances (RA) of Firmicutes and Faecalibacterium and lower RA of Bacteroidota and Escherichia-Shigella than participants with WDP. Only a small proportion of the variance in microbiota composition (1.8%) and its functional properties (2.9%) could be explained by dietary intake (legumes, simple sugars and their sources, like fruit, soft drinks) and stool transit characteristics.

CONCLUSION

Gut microbiota composition and predicted metabolic potential is shaped by overall diet quality as well as the frequency of defecation; however, the cumulative effect of these explain only a relatively low proportion of variance.

Gut microbiota, bile acids, and nature compounds

Natural compounds (NPs) have historically made a major contribution to pharmacotherapy in various diseases and drug discovery. In the past decades, studies on gut microbiota have shown that the efficacy of NPs can be affected by the interactions between gut microbiota and NPs. On one hand, gut microbiota can metabolize NPs. On the other hand, NPs can influence the metabolism and composition of gut microbiota. Among gut microbiota metabolites, bile acids (BAs) have attracted widespread attention due to their effects on the body homeostasis and the development of diseases. Studies have also confirmed that NPs can regulate the metabolism of BAs and ultimately regulate the physiological function of the body and disease progresses. In this review, we comprehensively summarize the interactions among NPs, gut microbiota, and BAs. In addition, we also discuss the role of microbial BAs metabolism in understanding the toxicity and efficacy of NPs. Furthermore, we present personal insights into the future research directions of NPs and BAs.

Gut microbiota predicts body fat change following a low-energy diet: a PREVIEW intervention study

Background

Low-energy diets (LEDs) comprise commercially formulated food products that provide between 800 and 1200 kcal/day (3.3–5 MJ/day) to aid body weight loss. Recent small-scale studies suggest that LEDs are associated with marked changes in the gut microbiota that may modify the effect of the LED on host metabolism and weight loss. We investigated how the gut microbiota changed during 8 weeks of total meal replacement LED and determined their associations with host response in a sub-analysis of 211 overweight adults with pre-diabetes participating in the large multicentre PREVIEW (PREVention of diabetes through lifestyle intervention and population studies In Europe and around the World) clinical trial.

Methods

Microbial community composition was analysed by Illumina sequencing of the hypervariable V3-V4 regions of the 16S ribosomal RNA (rRNA) gene. Butyrate production capacity was estimated by qPCR targeting the butyryl-CoA:acetate CoA-transferase gene. Bioinformatics and statistical analyses, such as comparison of alpha and beta diversity measures, correlative and differential abundances analysis, were undertaken on the 16S rRNA gene sequences of 211 paired (pre- and post-LED) samples as well as their integration with the clinical, biomedical and dietary datasets for predictive modelling.

Results

The overall composition of the gut microbiota changed markedly and consistently from pre- to post-LED (P = 0.001), along with increased richness and diversity (both P < 0.001). Following the intervention, the relative abundance of several genera previously associated with metabolic improvements (e.g., Akkermansia and Christensenellaceae R-7 group) was significantly increased (P < 0.001), while flagellated Pseudobutyrivibrio, acetogenic Blautia and Bifidobacterium spp. were decreased (all P < 0.001). Butyrate production capacity was reduced (P < 0.001). The changes in microbiota composition and predicted functions were significantly associated with body weight loss (P < 0.05). Baseline gut microbiota features were able to explain ~25% of variation in total body fat change (post–pre-LED).

Conclusions

The gut microbiota and individual taxa were significantly influenced by the LED intervention and correlated with changes in total body fat and body weight in individuals with overweight and pre-diabetes. Despite inter-individual variation, the baseline gut microbiota was a strong predictor of total body fat change during the energy restriction period.

Trial registration

The PREVIEW trial was prospectively registered at ClinicalTrials.gov (NCT01777893) on January 29, 2013.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13073-022-01053-7.

Preventive effects of traditional Chinese medicine formula Huoxiangzhengqi against lipopolysaccharide-induced inflammatory response

BACKGROUND

Huoxiangzhengqi oral liquid (HX), a pharmaceutical product made from traditional Chinese medicine formulas, has been commonly used in household medication for gastrointestinal disorders, but the mode of action remains largely unclear.

PURPOSE

This study aims to investigate whether pretreatment with HX prevents lipopolysaccharide (LPS)-induced adverse effects and the potential mechanisms involved.

METHODS

Seven-week-old male C57BL/6J mice were orally administered low (1.3 ml/kg) and high doses (2.6 ml/kg) of HX for 7 days, and subsequently subjected to a single dose of LPS at 6 mg/kg. Dexamethasone served as the positive control. Each group had ten animals.

RESULTS

The data demonstrated that either a low or high dose of HX significantly reduced the levels of inflammation induced by LPS in both small intestinal and cortical tissues. LPS profoundly decreased the richness and evenness of the microbiota and disrupted the composition of the intestinal microbial community, but pretreatment with HX did not successfully prevent dysbiosis. No significant improvements in HX against LPS were observed in intestinal local immunity or the secretion of partial gut-brain peptides. In addition, pretreatment with HX prevented the alterations in the expression levels of proteins related to the NF-κB pathway, including phospho-p38, p38, phospho-p44/42, p44/42, p50 and p65 induced by LPS.

CONCLUSION

Herein, we demonstrated for the first time that the preventive effects of HX against LPS mainly occur through the inhibition of inflammation. These findings provide novel evidence that HX may serve as a new agent for the prevention of gastrointestinal inflammation-related disorders.

Predictive Role of Gut Microbiota in Weight Loss Achievement after Bariatric Surgery

BACKGROUND

Bariatric surgery induces changes in gut microbiota that have been suggested to contribute to weight loss and metabolic improvement. However, whether preoperative gut microbiota composition could predict response to bariatric surgery has not yet been elucidated.

STUDY DESIGN

Seventy-six patients who underwent sleeve gastrectomy were classified according to the percentage of excess weight loss (%EWL) 1 year after surgery in the responder group: >50%EWL (n=50) and the nonresponder group: <50%EWL (n=26). Patients were evaluated before surgery, and 3 months and 1 year after surgery. Gut microbiota composition was analyzed before surgery (n=76) and 3 months after bariatric surgery (n=40).

RESULTS

Diversity analysis did not show differences between groups before surgery or 3 months after surgery. Before surgery, there were differences in the abundance of members belonging to Bacteroidetes and Firmicutes phyla (nonresponder group: enriched in Bacteroidaceae, Bacteroides, Bacteroides uniformis, Alistipes finegoldii, Alistipes alistipes, Dorea formicigenerans, and Ruminococcus gnavus. Responder group: enriched in Peptostreptococcaceae, Gemmiger, Gemiger formicilis, Barnesiella, Prevotellaceae, and Prevotella; linear discriminant analysis >2; p < 0.05). Prevotella-to-Bacteroides ratio was significantly lower in the nonresponder group compared to the responder group (p = 0.048). After surgery, the responder group showed an enrichment in taxa that have been shown to have beneficial effects on host metabolism. Before surgery, PICRUSt analysis showed an enrichment in pathways involved in the biosynthesis components of the O-antigen polysaccharideunits in lipopolysaccharides in the nonresponder group.

CONCLUSIONS

Preoperative gut microbiota could have an impact on bariatric surgery outcomes. Prevotella-to-Bacteroides ratio could be used as a predictive tool for weight loss trajectory. Early after surgery, patients who experienced successful weight loss showed an enrichment in taxa related to beneficial effects on host metabolism.

Current Insights into Potential Effects of Micro-Nanoplastics on Human Health by in-vitro Tests

Humans are exposed to micro and nanoplastics (MNPLs) through inhalation, ingestion and, to a lesser extent, dermal contact. In recent years, new insights indicate the potential of MNPLs to cause damages to human health. Particle toxicity can include oxidative stress, inflammatory lesions, and then increased internalization or translocation through tissues. On the other hand, plastic additives are used in plastic particles, once internalized, can release toxic substances. It is noteworthy that the potential effects of MNPLs encompass a wide range of polymers and chemical additives, showing various physicochemical and toxicological properties, and the size, shape and surface properties are other variables influencing their effects. In spite of the research carried out recently, MNPLs research is in its early stages, and further investigation is required. In this review article, the knowledge of human exposure routes and the recent results on the toxicological effects of MNPLs in human health are presented and discussed. Finally, the current limitations and the main gaps in the body of knowledge are summarised.

Chitosan Protects Immunosuppressed Mice Against Cryptosporidium parvum Infection Through TLR4/STAT1 Signaling Pathways and Gut Microbiota Modulation

Cryptosporidium parvum infection is very common in infants, immunocompromised patients, or in young ruminants, and chitosan supplementation exhibits beneficial effects against the infection caused by C. parvum. This study investigated whether chitosan supplementation modulates the gut microbiota and mediates the TLR4/STAT1 signaling pathways and related cytokines to attenuate C. parvum infection in immunosuppressed mice. Immunosuppressed C57BL/6 mice were divided into five treatment groups. The unchallenged mice received a basal diet (control), and three groups of mice challenged with 1 × 10⁶ C. parvum received a basal diet, a diet supplemented with 50 mg/kg/day paromomycin, and 1 mg/kg/day chitosan, and unchallenged mice treated with 1 mg/kg/day chitosan. Chitosan supplementation regulated serum biochemical indices and significantly (p < 0.01) reduced C. parvum oocyst excretion in infected mice treated with chitosan compared with the infected mice that received no treatment. Chitosan-fed infected mice showed significantly (p < 0.01) decreased mRNA expression levels of interferon-gamma (IFN-γ) and tumor necrosis factor-α (TNF-α) compared to infected mice that received no treatment. Chitosan significantly inhibited TLR4 and upregulated STAT1 protein expression (p < 0.01) in C. parvum-infected mice. 16S rRNA sequencing analysis revealed that chitosan supplementation increased the relative abundance of Bacteroidetes/Bacteroides, while that of Proteobacteria, Tenericutes, Defferribacteres, and Firmicutes decreased (p < 0.05). Overall, the findings revealed that chitosan supplementation can ameliorate C. parvum infection by remodeling the composition of the gut microbiota of mice, leading to mediated STAT1/TLR4 up- and downregulation and decreased production of IFN-γ and TNF-α, and these changes resulted in better resolution and control of C. parvum infection.

Water extract of Ferula lehmanni Boiss. prevents high-fat diet-induced overweight and liver injury by modulating the intestinal microbiota in mice

Obesity, often accompanied by hepatic steatosis, has been associated with an increased risk of health complications such as fatty liver disease and certain cancers. Ferula lehmannii Boiss., a food and medicine homologue, has been used for centuries as a seasoning showing anti-bacterial and anti-oxidant effects on digestive discomfort. In the present study, we sought to investigate whether a short-term oral administration of water extract of Ferula lehmanni Boiss. (WEFL) could prevent high-fat diet (HFD)-induced abnormal weight gain and hepatic steatosis in mice and its underlying mechanisms. WEFL reduced HFD-increased body weight, liver injury markers and inflammatory cytokines (i.e. IL-6 and IL-1β), and inhibited the elevation of AMPKα, SREBP-1c and FAS in HFD. Moreover, WEFL reconstructed the gut microbiota composition by increasing the relative abundances of beneficial bacteria, e.g. Akkermansia spp., while decreasing Desulfovibrio spp. and so on, thereby reversing the detrimental effects of HFD in mice. Removal of the gut microbiota with antibiotics partially eliminated the hepatoprotective effects of WEFL. Notably, WEFL substantially promoted the levels of short-chain fatty acids, especially butyric acid. To clarify the functional components at play in WEFL, we used UPLC-MS/MS to comprehensively detect its substance composition and found it to be a collection of polyphenol-rich compounds. Together, our findings demonstrate that WEFL prevented HFD-induced obesity and liver injury through the hepatic-microbiota axis, and such health-promoting value might be explained by the enriched abundant polyphenols.

Lipopolysaccharide lipid A: A promising molecule for new immunity-based therapies and antibiotics

Lipopolysaccharides (LPS) are the main components of the external leaflet of the Gram-negative outer membrane and consist of three different moieties: lipid A, core oligosaccharide, and O-polysaccharide. The lipid A is a glucosamine disaccharide with different levels of acylation and phosphorylation, beside carrying, in certain cases, additional substituents on the sugar backbone. It is also the main immunostimulatory part of the LPS, as its recognition by the host immune system represents a fundamental event for detection of perilous microorganisms. Moreover, an uncontrolled immune response caused by a large amount of circulating LPS can lead to dramatic outcomes for human health, such as septic shock. The immunostimulant properties of an LPS incredibly vary depending on lipid A chemical structure, and for this reason, natural and synthetic variants of the lipid A are under study to develop new drugs that mimic or antagonise its natural effects. Here, we review past and recent findings on the lipid A as an antibiotic target and immune-therapeutic molecule, with a special attention on the crucial role of the chemical structure and its exploitation for conceiving novel strategies for treatment of several immune-related pathologies.

Structure and Conformation Study of the O-Antigen from the Lipopolysaccharide of Cupriavidus Metallidurans CH34

Cupriavidus metallidurans is a Gram-negative bacterium that has attracted the attention of the scientific community since its discovery back in 1976. It was initially studied as a model organism for bioremediation processes due to its ability to survive in heavy metal-rich environments. However, in recent years, there is evidence that this bacterium can be a potential pathogen for humans. How C. metallidurans can survive in such different environments is unknown and prompted the following work. Its great adaptability could be explained by the structural and conformational studies of the O-antigen portion of the lipopolysaccharide, the main constituent of the outer membrane of Gram-negative bacteria, which is the one in direct contact with the external environment. Therefore, a combination of chemical and spectroscopic analyses was used to define the O-antigen structure, disclosing that it is a polysaccharide constituted of a linear tetrasaccharide repeating unit that does not resemble other structures already reported for bacteria: [4)-α-d-GalNAc-(1→3)-α-d-Qui2NAc4NHBA-(1→3)-α-l-Rha-(1→3)-α-l-Rha-(1→]. Interestingly, the molecular dynamics studies revealed that the three-dimensional structure of the O-antigen is highly flexible: it might adopt three different right-handed helix conformations described by a two, three, or four-fold symmetry. This conformational behavior could represent the reason behind the survival of C. metallidurans in different environments.