Bacteroides fragilis polysaccharide A induces IL-10 secreting B and T cells that prevent viral encephalitis

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.

An update on the effects of food-derived active peptides on the intestinal microecology

The intestinal microecology is a research hotspot, and neologisms related to the gut such as gut-brain axis, gut-lung axis, gut-bone axis, gut-skin axis, gut-renal axis, and gut-liver axis have emerged from recent research. Meticulous investigation has discovered that food-derived active peptides (FDAPs) are bioactive substances that optimize the structure of the gut microbiota to improve human health. However, few reviews have summarized and emphasized the nutritional value of FDAPs and their mechanisms of action in regulating the composition of the gut microbiota. We aim to provide an update on the latest research on FDAPs by comparing, summarizing, and discussing the potential food sources of FDAPs, their physiological functions, and regulatory effects on the intestinal microecology. The key findings are that few studies have analyzed the potential mechanisms and molecular pathways through which FDAPs maintain intestinal microecological homeostasis. We found that an imbalance in the ratio of Bacteroidetes and Firmicutes in the gut microbiota and abnormal production of short-chain fatty acids are key to the occurrence and development of various diseases. This review provides theoretical support for future comprehensive research on the digestion, distribution, metabolism, and excretion of FDAPs and the mechanisms underlying the interactions between FDAPs and the intestinal microecology.

The Interplay of Genital Herpes with Cellular Processes: A Pathogenesis and Therapeutic Perspective

Genital herpes, primarily caused by herpes simplex virus-2 (HSV-2), remains a pressing global health concern. Its remarkable ability to intertwine with cellular processes, from harnessing host machinery for replication to subverting antiviral defenses like autophagy and programmed cell death, exemplifies the intricate interplay at the heart of its pathogenesis. While the biomedical community has extensively researched antiviral interventions, the efficiency of these strategies in managing HSV-2 remains suboptimal. Recognizing this, attention has shifted toward leveraging host cellular components to regulate HSV-2 replication and influence the cell cycle. Furthermore, innovative interventional strategies-including drug repurposing, microbivacs, connecting the host microbiome, and exploiting natural secondary metabolites-are emerging as potential game changers. This review summarizes the key steps in HSV-2 pathogenesis and newly discovered cellular interactions, presenting the latest developments in the field, highlighting existing challenges, and offering a fresh perspective on HSV-2's pathogenesis and the potential avenues for its treatment by targeting cellular proteins and pathways.

Microbiota-derived short-chain fatty acids functions in the biology of B lymphocytes: From differentiation to antibody formation

Gut bacteria produce various metabolites from dietary fiber, the most abundant of which are short-chain fatty acids (SCFAs) such as acetate, propionate, and butyrate. Many biological functions, such as host metabolism and the immune system, are regulated by SCFAs because they act on a wide variety of cell types. A growing body of documents has shown that microbiota SCFAs directly regulate B-cell growth, proliferation, and immunoglobulin (Ig) production. As histone deacetylase (HDAC) inhibitors, SCFAs alter gene expression to enhance the expression of critical regulators of B cell growth. In particular, microbiota SCFAs increase the production of acetyl coenzyme A (acetyl-CoA), adenosine triphosphate (ATP), and fatty acids in B cells, which provide the energy and building blocks needed for the growth of plasma B cells. SCFAs play a significant role in promoting the involvement of B cells in host immunity during both homeostatic conditions and disease states. In this context, SCFAs stimulate B-cell activation and promote the differentiation of plasma B cells in response to B cell receptor (BCR)-activating antigens or co-stimulatory receptor ligands. The result may be increased production of IgA. Microbiota SCFAs were found to lower both overall and antigen-specific IgE levels, indicating their potential to mitigate IgE-related allergic reactions, much like their effect on class-switch recombination (CSR) towards IgG and IgA. Therefore, in the future, the therapeutic advantage should be to use specific and diffusible chemicals, such as SCFAs, which show a strong immunoregulatory function of B cells. This review focuses on the role of microbiota-produced SCFAs in regulating B cell development and antibody production, both in health and diseases.

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.

Gut Bacteroides act in a microbial consortium to cause susceptibility to severe malaria

Malaria is caused by Plasmodium species and remains a significant cause of morbidity and mortality globally. Gut bacteria can influence the severity of malaria, but the contribution of specific bacteria to the risk of severe malaria is unknown. Here, multiomics approaches demonstrate that specific species of Bacteroides are causally linked to the risk of severe malaria. Plasmodium yoelii hyperparasitemia-resistant mice gavaged with murine-isolated Bacteroides fragilis develop P. yoelii hyperparasitemia. Moreover, Bacteroides are significantly more abundant in Ugandan children with severe malarial anemia than with asymptomatic P. falciparum infection. Human isolates of Bacteroides caccae, Bacteroides uniformis, and Bacteroides ovatus were able to cause susceptibility to severe malaria in mice. While monocolonization of germ-free mice with Bacteroides alone is insufficient to cause susceptibility to hyperparasitemia, meta-analysis across multiple studies support a main role for Bacteroides in susceptibility to severe malaria. Approaches that target gut Bacteroides present an opportunity to prevent severe malaria and associated deaths.

Impact of the Microbiota on Viral Infections

The mammalian gastrointestinal tract (GIT) hosts a diverse and highly active microbiota composed of bacteria, eukaryotes, archaea, and viruses. Studies of the GIT microbiota date back more than a century, although modern techniques, including mouse models, sequencing technology, and novel therapeutics in humans, have been foundational to our understanding of the roles of commensal microbes in health and disease. Here, we review the impacts of the GIT microbiota on viral infection, both within the GIT and systemically. GIT-associated microbes and their metabolites alter the course of viral infection through a variety of mechanisms, including direct interactions with virions, alteration of the GIT landscape, and extensive regulation of innate and adaptive immunity. Mechanistic understanding of the full breadth of interactions between the GIT microbiota and the host is still lacking in many ways but will be vital for the development of novel therapeutics for viral and nonviral diseases alike.

Host microbiome in tuberculosis: disease, treatment, and immunity perspectives

Tuberculosis (TB), an airborne pulmonary disease caused by Mycobacterium tuberculosis (M. tb), poses an unprecedented health and economic burden to most of the developing countries. Treatment of TB requires prolonged use of a cocktail of antibiotics, which often manifest several side effects, including stomach upset, nausea, and loss of appetite spurring on treatment non-compliance and the emergence of antibiotic resistant M. tb. The anti-TB treatment regimen causes imbalances in the composition of autochthonous microbiota associated with the human body, which also contributes to major side effects. The microbiota residing in the gastrointestinal tract play an important role in various physiological processes, including resistance against colonization by pathogens, boosting host immunity, and providing key metabolic functions. In TB patients, due to prolonged exposure to anti-tuberculosis drugs, the gut microbiota significantly loses its diversity and several keystone bacterial taxa. This loss may result in a significant reduction in the functional potency of the microbiota, which is a probable reason for poor treatment outcomes. In this review, we discuss the structural and functional changes of the gut microbiota during TB and its treatment. A major focus of the review is oriented to the gut microbial association with micronutrient profiles and immune cell dynamics during TB infection. Furthermore, we summarize the acquisition of anti-microbial resistance in M. tb along with the microbiome-based therapeutics to cure the infections. Understanding the relationship between these components and host susceptibility to TB disease is important to finding potential targets that may be used in TB prevention, progression, and cure.

Protective effects of a new generation of probiotic Bacteroides fragilis against colitis in vivo and in vitro

Bacteroides fragilis, one of the potential next-generation probiotics, but its protective mechanism is not yet known. We aimed to characterize the anti-inflammatory effect of B. fragilisATCC25285 and to elucidate its mechanism through in vivo and in vitro experiments. An in vitro model of inflammation by induction of colonic cells with TNF-a, and co-cultured with B. fragilis to detect cell viability, apoptosis and invasive capacity. Furthermore, critical proteins of the TLR/NF-κB pathway and the inflammatory cytokines were measured. For animal trials, C57BL/6 J male mice were orally administered B. fragilis or PBS once daily for 21 days. Colitis was induced by drinking 2.5% DSS from days 0 to 7. The mice were weighed daily and rectal bleeding, stool condition and blood in the stool were recorded. We found that B. fragilis treatment alone was harmless and had no effect on cell viability or apoptosis. While predictably TNF-α decreased cell viability and increased apoptosis, B. fragilis attenuated this deterioration. The NF-κB pathway and inflammatory cytokines IL-6 and IL-1β activated by TNF-α were also blocked by B. fragilis. Notably, the metabolic supernatant of B. fragilis also has an anti-inflammatory effect. Animal studies showed that live B. fragilis rather than dead strain ameliorated DSS-induced colitis, as evidenced by weight loss, shortened colon length and enhanced barrier function. The colonic tissue levels of inflammatory cytokines (TNF-α, IL-1β, IL-6) were decreased and IL-10 was increased as a result of B. fragilis administration. In conclusion, B. fragilis ATCC25285 exhibited anti-inflammatory effects whether in vivo or in vitro, and it may be a potential probiotic agent for improving colitis.

A novel gut microbiome-immune axis influencing pathology in HCMV infected infants with neonatal cholestasis

The interplay of active HCMV infection with gut dysbiosis in the immunopathology of cholestasis in neonates and infants remains unexplored. In this study, we evaluated gut microbiome profiles and immune dysfunction in a cohort of HCMV infected cholestatic infants (IgM positive, N = 21; IgM negative, N = 25) compared to healthy infants, N = 10. HCMV infected IgM positive individuals exhibited increased clinical severity in terms of liver dysfunction, altered CD4+: CD8+ ratio, and elevated Granzyme B levels in cellular immune subsets. Gut microbiome analysis revealed distinct and differential diversity and composition within infected groups aligned with clinical severity reflected through the increased abundance of Gammaproteobacteria, reduced Bifidobacteria, and a unique signature mapping to the HCMV infected IgM negative group. Correlation analyses revealed associations between Bifidobacterium breve, Gammaproteobacteria, Firmicutes, Clostridia, Finegoldia magna, Veillonella dispar, and Granzyme B expressing immune cell subsets. Our study describes a novel gut microbiome-immune axis that may influence disease severity in cholestatic infants with active HCMV infection.

Improvements in Gut Microbiome Composition Predict the Clinical Efficacy of a Novel Synbiotics Formula in Children with Mild to Moderate Atopic Dermatitis

Atopic dermatitis (AD) is a common chronic inflammatory skin disease with a significant association with various type-2 inflammation-related comorbidities. Ongoing research suggests the crucial involvement of gut microbiome, especially in childhood onset AD, and hence, probiotics have emerged as a potential non-steroid-based therapeutics option to complement existing AD management plans. In order to delineate the impact of probiotics in the gut microbiome of pediatric AD patients from southern China, targeted 16S rRNA sequencing and thorough bioinformatic analysis were performed to analyze the gut microbiome profiles of 24 AD children after taking an orally administered novel synbiotics formula with triple prebiotics for 8 weeks. A notable improvement in Eczema Area and Severity Index (EASI) (p = 0.008) was observed after taking an 8-week course of probiotics, with no adverse effects observed. The relative abundances of key microbial drivers including Bacteroides fragilis and Lactobacillus acidophilus were significantly increased at week 8. We also found that the positive responsiveness towards an 8-week course of probiotics was associated with improvements in the gut microbiome profile with a higher relative abundance of probiotic species. Over-represented functional abundance pathways related to vitamin B synthesis and peptidoglycan recycling may imply the underlying mechanism. In summary, our study suggests how the gut microbial landscape shifts upon probiotic supplementation in AD children, and provides preliminary evidence to support targeted probiotic supplementation for the management of childhood AD.

Birth Mode Does Not Determine the Presence of Shared Bacterial Strains between the Maternal Vaginal Microbiome and the Infant Stool Microbiome

Dysbiosis of the neonatal gut microbiome during early life has been suggested as the missing link that may explain higher rates of certain diseases in caesarean section-delivered infants. Many studies report delivery mode-related dysbiosis in infants due to a lack of maternal vaginal microbiome exposure, prompting interventions to correct the neonatal gut microbiome by transferring these missing microbes after caesarean delivery. The maternal vaginal microbiome is among the first microbial exposures that many infants experience, yet little is known about the extent of direct transmission of maternal vaginal microbes. As part of the Maternal Microbiome Legacy Project, we aimed to determine if maternal vaginal bacteria are vertically transmitted to infants. We employed cpn60 microbiome profiling, culture-based screening, molecular strain typing, and whole-genome sequencing to determine whether identical maternal vaginal strains were present in infant stool microbiomes. We identified identical cpn60 sequence variants in both halves of maternal-infant dyads in 204 of 585 Canadian women and their newborn infants (38.9%). The same species of Bifidobacterium and Enterococcus were cultured from maternal and corresponding infant samples in 33 and 13 of these mother-infant dyads, respectively. Pulsed-field gel electrophoresis and whole-genome sequencing determined that near-identical strains were detected in these dyads irrespective of delivery mode, indicating an alternative source in cases of caesarean delivery. Overall, we demonstrated that vertical transmission of maternal vaginal microbiota is likely limited and that transmission from other maternal body sites, such as the gut and breast milk, may compensate for the lack of maternal vaginal microbiome exposure during caesarean delivery. IMPORTANCE The importance of the gut microbiome in human health and disease is widely recognized, and there has been a growing appreciation that alterations in gut microbiome composition during a "critical window" of development may impact health in later life. Attempts to correct gut microbiome dysbiosis related to birth mode are underpinned by the assumption that the lack of exposure to maternal vaginal microbes during caesarean delivery is responsible for dysbiosis. Here, we demonstrate that there is limited transmission of the maternal vaginal microbiome to the neonatal gut, even in cases of vaginal delivery. Furthermore, the presence of identical strains shared between mothers and infants in early life, even in cases of caesarean delivery, highlights compensatory microbial exposures and sources for the neonatal stool microbiome other than the maternal vagina.

An Update on Toll-like Receptor 2, Its Function and Dimerization in Pro- and Anti-Inflammatory Processes

While a certain level of inflammation is critical for humans to survive infection and injury, a prolonged inflammatory response can have fatal consequences. Pattern recognition Toll-like receptors (TLRs) are key players in the initiation of an inflammatory process. TLR2 is one of the most studied pattern recognition receptors (PRRs) and is known to form heterodimers with either TLR1, TLR4, TLR6, and TLR10, allowing it to recognize a wide range of pathogens. Although a large number of studies have been conducted over the past decades, there are still many unanswered questions regarding TLR2 mechanisms in health and disease. In this review, we provide an up-to-date overview of TLR2, including its homo- and heterodimers. Furthermore, we will discuss the pro- and anti-inflammatory properties of TLR2 and recent findings in prominent TLR2-associated infectious and neurodegenerative diseases.

Polyphenols and Their Impact on the Prevention of Neurodegenerative Diseases and Development

It is well known that neurodegenerative diseases' development and progression are accelerated due to oxidative stress and inflammation, which result in impairment of mitochondrial function, cellular damage, and dysfunction of DNA repair systems. The increased consumption of antioxidants can postpone the development of these disorders and improve the quality of patients' lives who have already been diagnosed with neurodegenerative diseases. Prolonging life span in developed countries contributes to an increase in the incidence ratio of chronic age-related neurodegenerative disorders, such as PD (Parkinson's disease), AD (Alzheimer's disease), or numerous forms of age-related dementias. Dietary supplementation with neuroprotective plant-derived polyphenols might be considered an important element of healthy aging. Some polyphenols improve cognition, mood, visual functions, language, and verbal memory functions. Polyphenols bioavailability differs greatly from one compound to another and is determined by solubility, degree of polymerization, conjugation, or glycosylation resulting from chemical structure. It is still unclear which polyphenols are beneficial because their potential depends on efficient transport across the BBB (blood-brain barrier), bioavailability, and stability in the CNS (central nervous system). Polyphenols improve brain functions by having a direct impact on cells and processes in the CNS. For a direct effect, polyphenolic compounds must be able to overcome the BBB and accumulate in brain tissue. In this review, the latest achievements in studies (animal models and clinical trials) on the effect of polyphenols on brain activity and function are described. The beneficial impact of plant polyphenols on the brain may be summarized by their role in increasing brain plasticity and related cognition improvement. As reversible MAO (monoamine oxidase) inhibitors, polyphenols are mood modulators and improve neuronal self-being through an increase in dopamine, serotonin, and noradrenaline amounts in the brain tissue. After analyzing the prohealth effects of various eating patterns, it was postulated that their beneficial effects result from synergistic interactions between individual dietary components. Polyphenols act on the brain endothelial cells and improve the BBB's integrity and reduce inflammation, thus protecting the brain from additional injury during stroke or autoimmune diseases. Polyphenolic compounds are capable of lowering blood pressure and improving cerebral blood flow. Many studies have revealed that a nutritional model based on increased consumption of antioxidants has the potential to ameliorate the cognitive impairment associated with neurodegenerative disorders. Randomized clinical trials have also shown that the improvement of cognitive functions resulting from the consumption of foods rich in flavonoids is independent of age and health conditions. For therapeutic use, sufficient quantities of polyphenols must cross the BBB and reach the brain tissue in active form. An important issue in the direct action of polyphenols on the CNS is not only their penetration through the BBB, but also their brain metabolism and localization. The bioavailability of polyphenols is low. The most usual oral administration also conflicts with bioavailability. The main factors that limit this process and have an effect on therapeutic efficacy are: selective permeability across BBB, gastrointestinal transformations, poor absorption, rapid hepatic and colonic metabolism, and systemic elimination. Thus, phenolic compounds have inadequate bioavailability for human applications to have any beneficial effects. In recent years, new strategies have been attempted in order to exert cognitive benefits and neuroprotective effects. Converting polyphenols into nanostructures is one of the theories proposed to enhance their bioavailability. The following nanoscale delivery systems can be used to encapsulate polyphenols: nanocapsules, nanospheres, micelles, cyclodextrins, solid lipid nanoparticles, and liposomes. It results in great expectations for the wide-scale and effective use of polyphenols in the prevention of neurodegenerative diseases. Thus far, only natural polyphenols have been studied as neuroprotectors. Perhaps some modification of the chemical structure of a given polyphenol may increase its neuroprotective activity and transportation through the BBB. However, numerous questions should be answered before developing neuroprotective medications based on plant polyphenols.

Glycolipids from the gut symbiont Bacteroides fragilis are agonists for natural killer T cells and induce their regulatory differentiation

Natural Killer T (NKT) cells are a lipid-antigen reactive T cell subset that is restricted to the antigen presenting molecule CD1d. They possess diverse functional properties that contribute to inflammatory and regulatory immune responses. The most studied lipid antigen target for these T cells is α-galactosylceramide (αGC). The commensal organism Bacteroides fragilis (B. fragilis) produces several forms of αGC, but conflicting information exists about the influence of these lipids on NKT cells. Herein, we report the total synthesis of a major form of αGC from B. fragilis (Bf αGC), and several analogues thereof. We confirm the T cell receptor (TCR)-mediated recognition of these glycolipids by mouse and human NKT cells. Despite the natural structure of Bf αGC containing lipid branching that limits potency, we demonstrate that Bf αGC drives mouse NKT cells to proliferate and differentiate into producers of the immunoregulatory cytokine, interleukin-10 (IL-10). These Bf αGC-experienced NKT cells display regulatory function by inhibiting the expansion of naïve NKT cells upon subsequent exposure to this antigen. Moreover, this regulatory activity impacts more than just NKT cells, as demonstrated by the NKT cell-mediated inhibition of antigen-stimulated mucosal-associated invariant T (MAIT) cells (a T cell subset restricted to a different antigen presenting molecule, MR1). These findings reveal that B. fragilis-derived NKT cell agonists may have broad immunoregulatory activity, providing insight into the mechanisms influencing immune tolerance to commensal bacteria and highlighting a potential means to manipulate NKT cell function for therapeutic benefit.

Avenues within the gut-liver-brain axis linking chronic liver disease and symptoms

Symptoms of fatigue, social withdrawal and mood disturbances are commonly encountered in patients with chronic liver disease and have a detrimental effect on patient quality of life. Treatment options for these symptoms are limited and a current area of unmet medical need. In this review, we will evaluate the potential mechanistic avenues within the gut-liver-brain axis that may be altered in the setting of chronic liver disease that drive the development of these symptoms. Both clinical and pre-clinical studies will be highlighted as we discuss how perturbations in host immune response, microbiome, neural responses, and metabolites composition can affect the central nervous system.

Oral and anal microbiome from HIV-exposed individuals: role of host-associated factors in taxa composition and metabolic pathways

Evidence indicates that the microbiome plays a significant role in HIV immunopathogenesis and associated complications. This study aimed to characterize the oral and anal microbiome of Men who have Sex with Men (MSM) and Transgender Women (TGW), with and without HIV. One hundred and thirty oral and anal DNA-derived samples were obtained from 78 participants and subjected to shotgun metagenomics sequencing for further microbiome analysis. Significant differences in the microbiome composition were found among subjects associated with HIV infection, gender, sex behavior, CD4+ T-cell counts, antiretroviral therapy (ART), and the presence of HPV-associated precancerous anal lesions. Results confirm the occurrence of oncogenic viromes in this high HIV-risk population. The oral microbiome in HIV-associated cases exhibited an enrichment of bacteria associated with periodontal disease pathogenesis. Conversely, anal bacteria showed a significant decrease in HIV-infected subjects (Coprococcus comes, Finegoldia magna, Blautia obeum, Catenibacterium mitsuokai). TGW showed enrichment in species related to sexual transmission, which concurs that most recruited TGW are or have been sex workers. Prevotella bivia and Fusobacterium gonidiaformans were positively associated with anal precancerous lesions among HIV-infected subjects. The enrichment of Holdemanella biformis and C. comes was associated with detectable viral load and ART-untreated patients. Metabolic pathways were distinctly affected by predominant factors linked to sexual behavior or HIV pathogenesis. Gene family analysis identified bacterial gene signatures as potential prognostic and predictive biomarkers for HIV/AIDS-associated malignancies. Conclusions: Identified microbial features at accessible sites are potential biomarkers for predicting precancerous anal lesions and therapeutic targets for HIV immunopathogenesis.

When the allergy alarm bells toll: The role of Toll-like receptors in allergic diseases and treatment

Toll-like receptors of the human immune system are specialized pathogen detectors able to link innate and adaptive immune responses. TLR ligands include among others bacteria-, mycoplasma- or virus-derived compounds such as lipids, lipo- and glycoproteins and nucleic acids. Not only are genetic variations in TLR-related genes associated with the pathogenesis of allergic diseases, including asthma and allergic rhinitis, their expression also differs between allergic and non-allergic individuals. Due to a complex interplay of genes, environmental factors, and allergen sources the interpretation of TLRs involved in immunoglobulin E-mediated diseases remains challenging. Therefore, it is imperative to dissect the role of TLRs in allergies. In this review, we discuss i) the expression of TLRs in organs and cell types involved in the allergic immune response, ii) their involvement in modulating allergy-associated or -protective immune responses, and iii) how differential activation of TLRs by environmental factors, such as microbial, viral or air pollutant exposure, results in allergy development. However, we focus on iv) allergen sources interacting with TLRs, and v) how targeting TLRs could be employed in novel therapeutic strategies. Understanding the contributions of TLRs to allergy development allow the identification of knowledge gaps, provide guidance for ongoing research efforts, and built the foundation for future exploitation of TLRs in vaccine design.

Alteration of the Gut Microbiota in Pigs Infected with African Swine Fever Virus

The factors that influence the pathogenicity of African swine fever (ASF) are still poorly understood, and the host's immune response has been indicated as crucial. Although an increasing number of studies have shown that gut microbiota can control the progression of diseases caused by viral infections, it has not been characterized how the ASF virus (ASFV) changes a pig's gut microbiome. This study analyzed the dynamic changes in the intestinal microbiome of pigs experimentally infected with the high-virulence ASFV genotype II strain (N = 4) or mock strain (N = 3). Daily fecal samples were collected from the pigs and distributed into the four phases (before infection, primary phase, clinical phase, and terminal phase) of ASF based on the individual clinical features of the pigs. The total DNA was extracted and the V4 region of the 16 s rRNA gene was amplified and sequenced on the Illumina platform. Richness indices (ACE and Chao1) were significantly decreased in the terminal phase of ASF infection. The relative abundances of short-chain-fatty-acids-producing bacteria, such as Ruminococcaceae, Roseburia, and Blautia, were decreased during ASFV infection. On the other hand, the abundance of Proteobacteria and Spirochaetes increased. Furthermore, predicted functional analysis using PICRUSt resulted in a significantly reduced abundance of 15 immune-related pathways in the ASFV-infected pigs. This study provides evidence for further understanding the ASFV-pig interaction and suggests that changes in gut microbiome composition during ASFV infection may be associated with the status of immunosuppression.

Clinical translation of anti-inflammatory effects of Prevotella histicola in Th1, Th2, and Th17 inflammation

Introduction

EDP1815 is a non-colonizing pharmaceutical preparation of a single stain of Prevotella histicola isolated from the duodenum of a human donor. We report here preclinical and clinical studies showing that the action of EDP1815, an orally delivered and gut restricted single strain of commensal bacteria can regulate inflammatory responses throughout the body.

Methods

Supported by evidence for anti-inflammatory activity in three preclinical mouse models of Th1-, TH2-, and Th17-mediated inflammation, EDP1815 was tested clinically in three Phase 1b studies in patients with psoriasis, patients with atopic dermatitis, and healthy volunteers in a KLH skin challenge model.

Results

Preclinically, EDP1815 was efficacious in all three mouse models of inflammation, showing reduction in skin inflammation as well as related tissue cytokines. In the Phase 1b studies, EDP1815 was found to be well tolerated by participants, with a safety profile comparable to placebo, including no severe or consistent side-effects reported, and no evidence of immunosuppression with no opportunistic infection occurring in these studies. In psoriasis patients, signs of clinical efficacy were seen after 4 weeks of treatment, which continued beyond the treatment period in the higher-dose cohort. In atopic dermatitis patients, improvements were seen throughout the key physician-and patient-reported outcomes. In a healthy-volunteer study of a KLH-induced skin inflammatory response, consistent anti-inflammatory effects were seen in two cohorts through imaging-based measures of skin inflammation.

Discussion

This is the first report demonstrating clinical effects from targeting peripheral inflammation with a non-colonizing gut-restricted single strain of commensal bacteria, providing proof of concept for a new class of medicines. These clinical effects occur without systemic exposure of EDP1815 or modification of the resident gut microbiota, and with placebo-like safety and tolerability. The breadth of these clinical effects of EDP1815, combined with its excellent safety and tolerability profile and oral administration, suggests the potential for a new type of effective, safe, oral, and accessible anti-inflammatory medicine to treat the wide range of diseases driven by inflammation.Clinical Trial Registration: EudraCT # 2018-002807-32; EudraCT # 2018-002807-32; NL8676; https://clinicaltrials.gov/ct2/show/NCT03733353; http://www.trialregister.nl.

The immunomodulatory roles of the gut microbiome in autoimmune diseases of the central nervous system: Multiple sclerosis as a model

The gut-associated lymphoid tissue is a primary activation site for immune responses to infection and immunomodulation. Experimental evidence using animal disease models suggests that specific gut microbes significantly regulate inflammation and immunoregulatory pathways. Furthermore, recent clinical findings indicate that gut microbes' composition, collectively named gut microbiota, is altered under disease state. This review focuses on the functional mechanisms by which gut microbes promote immunomodulatory responses that could be relevant in balancing inflammation associated with autoimmunity in the central nervous system. We also propose therapeutic interventions that target the composition of the gut microbiota as immunomodulatory mechanisms to control neuroinflammation.

Enhancing Regulatory T Cells to Treat Inflammatory and Autoimmune Diseases

Regulatory T cells (Tregs) control immune responses and are essential to maintain immune homeostasis and self-tolerance. Hence, it is no coincidence that autoimmune and chronic inflammatory disorders are associated with defects in Tregs. These diseases have currently no cure and are treated with palliative drugs such as immunosuppressant and immunomodulatory agents. Thereby, there is a great interest in developing medical interventions against these diseases based on enhancing Treg cell function and numbers. Here, we give an overview of Treg cell ontogeny and function, paying particular attention to mucosal Tregs. We review some notable approaches to enhance immunomodulation by Tregs with therapeutic purposes including adoptive Treg cell transfer therapy and discuss relevant clinical trials for inflammatory bowel disease. We next introduce ways to expand mucosal Tregs in vivo using microbiota and dietary products that have been the focus of clinical trials in various autoimmune and chronic-inflammatory diseases.

Association of lung-intestinal microecology and lung cancer therapy

In recent years, the incidence of lung cancer is increasing. Lung cancer has become one of the most malignant tumors with the highest incidence in the world, which seriously affects people's health. The most important cause of death of lung cancer is metastasis. Therefore, it is crucial to understand the mechanism of lung cancer progression and metastasis. This review article discusses the physiological functions, pathological states and disorders of the lung and intestine based on the concepts of traditional Chinese medicine (TCM), and analyzes the etiology and mechanisms of lung cancer formation from the perspective of TCM. From the theory of "the exterior and interior of the lung and gastrointestinal tract", the theory of "the lung-intestinal axis" and the progression and metastasis of lung cancer, we proposed e "lung-gut co-treatment" therapy for lung cancer. This study provides ideas for studying the mechanism of lung cancer and the comprehensive alternative treatment for lung cancer patients.

Effects of Lactobacillus casei NCU011054 on immune response and gut microbiota of cyclophosphamide induced immunosuppression mice

Lactobacillus (L.) casei NCU011054 isolated from infant feces has been proven to be a potential probiotic in vitro. The present study aimed to investigate the effects of L. casei NCU011054 on the immune response and gut microbiota in cyclophosphamide (CP)-induced immunosuppression mice. Results indicated that L. casei NCU011054 could increase the levels of mucin (Muc2) and tight junction proteins (ZO-1, occludin and claudin-1). Moreover, L. casei NCU011054 was found to upregulate TLRs/NF-κB pathway (TLR-2, TLR-4, TLR-6, p65 and NF-κB) and two transcription factors (T-bet and GATA-3) mRNA levels, and enhance the number of CD4⁺T cells. Th1-related cytokines (IL-12p70, IFN-γ and TNF-α) and Th2-related cytokines (IL-2, IL-4, IL-6 and IL-10) significantly increased after L. casei NCU011054 treatment. More importantly, L. casei NCU011054 increased the ratio of T-bet to GATA-3 and IFN-γ to IL-4. Apart from these, L. casei NCU011054 remodeled gut microbiota and modulated gut metabolites in CP-induced immunosuppressed mice. The correlation analysis showed that Lactobacillus upregulated by L. casei NCU011054 was positively correlated with TLRs/NF-κB pathway, and the ratio of T-bet to GATA-3 and IFN-γ to IL-4. All findings revealed that L. casei NCU011054 could improve intestinal immune dysfunction and modulate Th1/Th2 balance via TLRs/NF-κB pathway in CP-induced immunosuppressed mice.

Metabolic-Dysfunction-Associated Fatty Liver Disease and Gut Microbiota: From Fatty Liver to Dysmetabolic Syndrome

Metabolic-dysfunction-associated fatty liver disease (MAFLD) is the recent nomenclature designation that associates the condition of non-alcoholic fatty liver disease (NAFLD) with metabolic dysfunction. Its diagnosis has been debated in the recent period and is generally associated with a diagnosis of steatosis and at least one pathologic condition among overweight/obesity, type 2 diabetes mellitus, and metabolic dysregulation. Its pathogenesis is defined by a “multiple-hit” model and is associated with alteration or dysbiosis of the gut microbiota. The pathogenic role of dysbiosis of the gut microbiota has been investigated in many diseases, including obesity, type 2 diabetes mellitus, and NAFLD. However, only a few works correlate it with MAFLD, although common pathogenetic links to these diseases are suspected. This review underlines the most recurrent changes in the gut microbiota of patients with MAFLD, while also evidencing possible pathogenetic links.

The crosstalk between intestinal bacterial microbiota and immune cells in colorectal cancer progression

Different types of cells that are involved in tumor immunity play a significant part in antitumor therapy. The intestinal microbiota consist of the trillions of diverse microorganisms that inhabit the gastrointestinal tract. Recently, much emphasis has been paid to the link between these symbionts and colorectal cancer (CRC). This association might be anything from oncogenesis and cancer development to resistance or susceptibility to chemotherapeutic medicines. Cancer patients have a significantly different microbial composition in their guts compared to healthy persons. The microbiome may play a role in the development and development of cancer through the modulation of tumor immunosurveillance, as shown by these studies; however, the specific processes underlying this role are still poorly understood. This review focuses on the relationship between the intestinal bacterial microbiota and immune cells to determine how the commensal microbiome influences the initiation and development of CRC.

Mechanisms of Immune-Related Long Non-Coding RNAs in Spleens of Mice Vaccinated with 23-Valent Pneumococcal Polysaccharide Vaccine (PPV23)

The 23-valent pneumococcal vaccine (PPV23) is a classical common vaccine used to prevent pneumococcal disease. In past decades, it was thought that vaccination with this vaccine induces humoral immunity, thereby reducing the disease associated with infection with 23 common serotypes of Streptococcus pneumoniae (Sp). However, for this polysaccharide vaccine, the mechanism of immune response at the transcriptional level has not been fully studied. To identify the lncRNAs (long noncoding RNAs) and mRNAs in spleens related to immunity after PPV23 vaccination in mice, high-throughput RNA sequencing of spleens between a PPV23 treatment group and a control group were performed and evaluated in this study. The RNA-seq results identified a total of 41,321 mRNAs and 34,375 lncRNAs, including 55 significantly differentially expressed (DE) mRNAs and 389 DE lncRNAs (p < 0.05) between the two groups. GO and KEGG annotation analysis indicated that the target genes of DE lncRNAs and DE mRNAs were related to T-cell costimulation, positive regulation of alpha–beta T-cell differentiation, the CD86 biosynthetic process, and the PI3K-Akt signaling pathway, indicating that the polysaccharide component antigens of PPV23 might activate a cellular immune response during the PPV23 immunization process. Moreover, we found that Trim35 (tripartite motif containing 35), a target gene of lncRNA MSTRG.9127, was involved in regulating immunity. Our study provides a catalog of lncRNAs and mRNAs associated with immune cells’ proliferation and differentiation, and they deserve further study to deepen the understanding of the biological processes in the regulation of PPV23 during humoral immunity and cellular immunity.

An Archetypical Model for Engrafting Bacteroides fragilis into Conventional Mice Following Reproducible Antibiotic Conditioning of the Gut Microbiota

Bacteroides fragilis is a commonly investigated commensal bacterium for its protective role in host diseases. Here, we aimed to develop a reproducible antibiotic-based model for conditioning the gut microbiota and engrafting B. fragilis into a conventional murine host. Initially, we selected different combinations of antibiotics, including metronidazole, imipenem, and clindamycin, and investigated their efficacy in depleting the mouse Bacteroides population. We performed 16S rRNA sequencing of DNA isolated from fecal samples at different time points. The α-diversity was similar in mice treated with metronidazole (MET) and differed only at weeks 1 (p = 0.001) and 3 (p = 0.009) during metronidazole/imipenem (MI) treatment. Bacteroides compositions, during the MET and MI exposures, were similar to the pre-antibiotic exposure states. Clindamycin supplementation added to MET or MI regimens eliminated the Bacteroides population. We next repeated metronidazole/clindamycin (MC) treatment in two additional independent experiments, followed by a B. fragilis transplant. MC consistently and reproducibly eliminated the Bacteroides population. The depleted Bacteroides did not recover in a convalescence period of six weeks post-MC treatment. Finally, B. fragilis was enriched for ten days following engraftment into Bacteroides-depleted mice. Our model has potential use in gut microbiota studies that selectively investigate Bacteroides' role in diseases of interest.

Effect of curcumin on regulatory B cells in chronic colitis mice involving TLR/MyD88 signaling pathway

Curcumin (Cur) is a natural active phenolic compound extracted from the root of Curcuma Longa L. It has anti-inflammatory, anti-tumor and other pharmacological activities, and is commonly used to treat ulcerative colitis (UC). However, it is not clear whether curcumin regulates the function and differentiation of Breg cells to treat UC. In this study, mice with chronic colitis were induced by dextran sulfate sodium (DSS), and treated with curcumin for 12 days. Curcumin effectively improved the body weight, colonic weight, colonic length, decreased colonic weight index and pathological injury score under colonoscopy in mice with chronic colitis, and significantly inhibited the production of IL-1β, IL-6, IL-33, CCL-2, IFN-γ, TNF-α, and promoted the secretion of IL-4, IL-10, IL-13 and IgA. Importantly, curcumin markedly upregulated CD3- CD19+ CD1d+ , CD3- CD19+ CD25+ , CD3- CD19+ Foxp3+ Breg cells level and significantly down-regulated CD3- CD19+ PD-L1+ , CD3- CD19+ tim-1+ , CD3- CD19+ CD27+ Breg cells level. In addition, our results also showed that curcumin observably inhibited TLR2, TLR4, TLR5, MyD88, IRAK4, p-IRAK4, NF-κB P65, IRAK1, TRAF6, TAB1, TAB2, TAK1, MKK3, MKK6, p38MAPK, p-p38MAPK and CREB expression in TLR/MyD88 signaling pathway. These results suggest that curcumin can regulate the differentiation and function of Breg cell to alleviate DSS-induced colitis, which may be realized by inhibiting TLR/MyD88 pathway.

Immunological consequences of microbiome-based therapeutics

The complex network of microscopic organisms living on and within humans, collectively referred to as the microbiome, produce wide array of biologically active molecules that shape our health. Disruption of the microbiome is associated with susceptibility to a range of diseases such as cancer, diabetes, allergy, obesity, and infection. A new series of next-generation microbiome-based therapies are being developed to treat these diseases by transplanting bacteria or bacterial-derived byproducts into a diseased individual to reset the recipient's microbiome and restore health. Microbiome transplantation therapy is still in its early stages of being a routine treatment option and, with a few notable exceptions, has had limited success in clinical trials. In this review, we highlight the successes and challenges of implementing these therapies to treat disease with a focus on interactions between the immune system and microbiome-based therapeutics. The immune activation status of the microbiome transplant recipient prior to transplantation has an important role in supporting bacterial engraftment. Following engraftment, microbiome transplant derived signals can modulate immune function to ameliorate disease. As novel microbiome-based therapeutics are developed, consideration of how the transplants will interact with the immune system will be a key factor in determining whether the microbiome-based transplant elicits its intended therapeutic effect.

Novel potential therapeutic targets of alopecia areata

Alopecia areata (AA) is a non-scarring hair loss disorder caused by autoimmunity. The immune collapse of the hair follicle, where interferon-gamma (IFN-γ) and CD8+ T cells accumulate, is a key factor in AA. However, the exact functional mechanism remains unclear. Therefore, AA treatment has poor efficacy maintenance and high relapse rate after drug withdrawal. Recent studies show that immune-related cells and molecules affect AA. These cells communicate through autocrine and paracrine signals. Various cytokines, chemokines and growth factors mediate this crosstalk. In addition, adipose-derived stem cells (ADSCs), gut microbiota, hair follicle melanocytes, non-coding RNAs and specific regulatory factors have crucial roles in intercellular communication without a clear cause, suggesting potential new targets for AA therapy. This review discusses the latest research on the possible pathogenesis and therapeutic targets of AA.

Protective role of colitis in inflammatory arthritis via propionate-producing Bacteroides in the gut

Objectives

To investigate whether and how inflammatory disease in the intestine influences the development of arthritis, considering that organ-to-organ communication is associated with many physiological and pathological events.

Methods

First, mice were given drinking water containing dextran sodium sulfate (DSS) and then subjected to inflammatory arthritis. We compared the phenotypic symptoms between the cohoused and separately-housed mice. Next, donor mice were divided into DSS-treated and untreated groups and then cohoused with recipient mice. Arthritis was then induced in the recipients. The fecal microbiome was analyzed by 16S rRNA amplicon sequencing. We obtained type strains of the candidate bacteria and generated propionate-deficient mutant bacteria. Short-chain fatty acids were measured in the bacterial culture supernatant, serum, feces, and cecum contents using gas chromatography-mass spectrometry. Mice fed with candidate and mutant bacteria were subjected to inflammatory arthritis.

Results

Contrary to expectations, the mice treated with DSS exhibited fewer symptoms of inflammatory arthritis. Intriguingly, the gut microbiota contributes, at least in part, to the improvement of colitis-mediated arthritis. Among the altered microorganisms, Bacteroides vulgatus and its higher taxonomic ranks were enriched in the DSS-treated mice. B. vulgatus, B. caccae, and B. thetaiotaomicron exerted anti-arthritic effects. Propionate production deficiency further prevented the protective effect of B. thetaiotaomicron on arthritis.

Conclusions

We suggest a novel relationship between the gut and joints and an important role of the gut microbiota as communicators. Moreover, the propionate-producing Bacteroides species examined in this study may be a potential candidate for developing effective treatments for inflammatory arthritis.

How Toll-like receptors influence Parkinson's disease in the microbiome-gut-brain axis

Recently, a large number of experimenters have found that the pathogenesis of Parkinson's disease may be related to the gut microbiome and proposed the microbiome-gut-brain axis. Studies have shown that Toll-like receptors, especially Toll-like receptor 2 (TLR2) and Toll-like receptor 4 (TLR4), are key mediators of gut homeostasis. In addition to their established role in innate immunity throughout the body, research is increasingly showing that the Toll-like receptor 2 and Toll-like receptor 4 signaling pathways shape the development and function of the gut and enteric nervous system. Notably, Toll-like receptor 2 and Toll-like receptor 4 are dysregulated in Parkinson's disease patients and may therefore be identified as the core of early gut dysfunction in Parkinson's disease. To better understand the contribution of Toll-like receptor 2 and Toll-like receptor 4 dysfunction in the gut to early α-synuclein aggregation, we discussed the structural function of Toll-like receptor 2 and Toll-like receptor 4 and signal transduction of Toll-like receptor 2 and Toll-like receptor 4 in Parkinson's disease by reviewing clinical, animal models, and in vitro studies. We also present a conceptual model of the pathogenesis of Parkinson's disease, in which microbial dysbiosis alters the gut barrier as well as the Toll-like receptor 2 and Toll-like receptor 4 signaling pathways, ultimately leading to a positive feedback loop for chronic gut dysfunction, promoting α-synuclein aggregation in the gut and vagus nerve.

Let’s review the gut microbiota in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a chronic, immune-mediated disease associated with significant morbidity and mortality. New evidence suggests that diet, gut microbiota, intestinal permeability, and endotoxemia may modulate chronic inflammation and disease activity in SLE. This review focus on what is known about the gut microbiota in lupus mouse models and SLE patients and the possible mechanisms that connect the gut microbiota with SLE. It included 29 studies (12 animal studies, 15 human studies, and 2 included data on both), with variable results regarding alpha and beta-diversity and gut microbiota composition between lupus-mouse models and SLE patients. Ruminococcus (R.) gnavus was significantly increased in lupus nephritis (LN) in one study, but this was not corroborated by others. Despite the different results, mechanistic lupus mouse model studies have shown that gut microbiota can modulate disease activity. Interestingly, pathobiont translocation in monocolonized and autoimmune-prone mice induced autoantibodies and caused mortality, which could be prevented by a vaccine targeting the pathobiont. Moreover, studies on fecal transplants and diet on different lupus mouse models showed an effect on disease activity. In SLE patients, a higher adherence to the Mediterranean diet was associated with lower disease activity, which may be explained by the connection between diet and gut microbiota. Although gut dysbiosis has been observed in SLE patients and lupus mouse models, it remains to clarify if it is a cause or a consequence of the disease or its treatments. Further studies with larger and well-characterized populations will undoubtedly contribute to deciphering the role of gut microbiota in SLE development, progression, and outcome.

Next-Generation Probiotics: Microflora Intervention to Human Diseases

With the development of human genome sequencing and techniques such as intestinal microbial culture and fecal microbial transplantation, newly discovered microorganisms have been isolated, cultured, and researched. Consequently, many beneficial probiotics have emerged as next-generation probiotics (NGPs). Currently, "safety," "individualized treatment," and "internal interaction within the flora" are requirements of a potential NGPs. Furthermore, in the complex ecosystem of humans and microbes, it is challenging to identify the relationship between specific strains, specific flora, and hosts to warrant a therapeutic intervention in case of a disease. Thus, this review focuses on the progress made in NGPs and human health research by elucidating the limitations of traditional probiotics; summarizing the functions and strengths of Akkermansia muciniphila, Faecalibacterium prausnitzii, Bacteroides fragilis, Eubacterium hallii, and Roseburia spp. as NGPs; and determining the role of their intervention in treatment of certain diseases. Finally, we aim to provide a reference for developing new probiotics in the future.

Bacteroides fragilis derived metabolites, identified by molecular networking, decrease Salmonella virulence in mice model

In the gut microbiota, resident bacteria prevent pathogens infection by producing specific metabolites. Among bacteria belonging to phylum Bacteroidota, we have previously shown that Bacteroides fragilis or its cell-free supernatant inhibited in vitro Salmonella Heidelberg translocation. In the present study, we have analyzed this supernatant to identify bioactive molecules after extraction and subsequent fractionation using a semi-preparative reversed-phase Liquid Chromatography High-Resolution Tandem Mass Spectrometry (LC-HRMS/MS). The results indicated that only two fractions (F3 and F4) strongly inhibited S. Heidelberg translocation in a model mimicking the intestinal epithelium. The efficiency of the bioactive fractions was evaluated in BALB/c mice, and the results showed a decrease of S. Heidelberg in Peyer’s patches and spleen, associated with a decrease in inflammatory cytokines and neutrophils infiltration. The reduction of the genus Alistipes in mice receiving the fractions could be related to the anti-inflammatory effects of bioactive fractions. Furthermore, these bioactive fractions did not alter the gut microbiota diversity in mice. To further characterize the compounds present in these bioactive fractions, Liquid Chromatography High-Resolution Tandem Mass Spectrometry (LC-HRMS/MS) data were analyzed through molecular networking, highlighting cholic acid (CA) and deoxycholic acid. In vitro, CA had inhibitory activity against the translocation of S. Heidelberg by significantly decreasing the expression of Salmonella virulence genes such as sipA. The bioactive fractions also significantly downregulated the flagellar gene fliC, suggesting the involvement of other active molecules. This study showed the interest to characterize better the metabolites produced by B. fragilis to make them means of fighting pathogenic bacteria by targeting their virulence factor without modifying the gut microbiota.

A metagenome-wide association study of the gut microbiota in recurrent aphthous ulcer and regulation by thalidomide

Recurrent aphthous ulcer (RAU), one of the most common diseases in humans, has an unknown etiology and is difficult to treat. Thalidomide is an important immunomodulatory and antitumor drug and its effects on the gut microbiota still remain unclear. We conducted a metagenomic sequencing study of fecal samples from a cohort of individuals with RAU, performed biochemical assays of cytokines, immunoglobulins and antimicrobial peptides in serum and saliva, and investigated the regulation effects of thalidomide administration and withdrawal. Meanwhile we constructed the corresponding prediction models. Our metagenome-wide association results indicated that gut dysbacteriosis, microbial dysfunction and immune imbalance occurred in RAU patients. Thalidomide regulated gut dysbacteriosis in a species-specific manner and had different sustainable effects on various probiotics and pathogens. A previously unknown association between gut microbiota alterations and RAU was found, and the specific roles of thalidomide in modulating the gut microbiota and immunity were determined, suggesting that RAU may be affected by targeting gut dysbacteriosis and modifying immune imbalance. In-depth insights into sophisticated networks consisting of the gut microbiota and host cells may lead to the development of emerging treatments, including prebiotics, probiotics, synbiotics, and postbiotics.

M, Zarrintaj P, Formela K, Saeb MR, Bencherif SA. Clickable Polysaccharides for Biomedical Applications: A Comprehensive Review

Recent advances in materials science and engineering highlight the importance of designing sophisticated biomaterials with well-defined architectures and tunable properties for emerging biomedical applications. Click chemistry, a powerful method allowing specific and controllable bioorthogonal reactions, has revolutionized our ability to make complex molecular structures with a high level of specificity, selectivity, and yield under mild conditions. These features combined with minimal byproduct formation have enabled the design of a wide range of macromolecular architectures from quick and versatile click reactions. Furthermore, copper-free click chemistry has resulted in a change of paradigm, allowing researchers to perform highly selective chemical reactions in biological environments to further understand the structure and function of cells. In living systems, introducing clickable groups into biomolecules such as polysaccharides (PSA) has been explored as a general approach to conduct medicinal chemistry and potentially help solve healthcare needs. De novo biosynthetic pathways for chemical synthesis have also been exploited and optimized to perform PSA-based bioconjugation inside living cells without interfering with their native processes or functions. This strategy obviates the need for laborious and costly chemical reactions which normally require extensive and time-consuming purification steps. Using these approaches, various PSA-based macromolecules have been manufactured as building blocks for the design of novel biomaterials. Clickable PSA provides a powerful and versatile toolbox for biomaterials scientists and will increasingly play a crucial role in the biomedical field. Specifically, bioclick reactions with PSA have been leveraged for the design of advanced drug delivery systems and minimally invasive injectable hydrogels. In this review article, we have outlined the key aspects and breadth of PSA-derived bioclick reactions as a powerful and versatile toolbox to design advanced polymeric biomaterials for biomedical applications such as molecular imaging, drug delivery, and tissue engineering. Additionally, we have also discussed the past achievements, present developments, and recent trends of clickable PSA-based biomaterials such as 3D printing, as well as their challenges, clinical translatability, and future perspectives.

Modulation of the intestinal microbiota impacts the efficacy of immunotherapy in cancer patients - A recent literature survey

In line with the current development of individualized cancer treatments, targeted and specialized therapeutic regimens such as immunotherapy gain importance and factors improving its efficacy come into the focus of actual research. Given the orchestrated interaction of the intestinal microbiota with host immunity the modulation of the human gut microbiota represents a therapy-enhancing factor. We therefore performed an actual literature survey on the role of the gut microbiota composition and the effects of its modification during immunotherapy of cancer patients. The included 23 studies published in the past 10 years revealed that both, distinct bacterial species and genera including Faecalibacterium prausnitzii and Bifidobacterium, respectively, enhanced distinct immunotherapy responses following PD-1/PD-L1 and CTLA-4 blockage, for instance, resulting in a better clinical outcome of cancer patients. Conversely, a high intestinal abundance of Bacteroidetes and Fusobacterium species correlated with a less efficient immunotherapy resulting in shorter progress-free survival outcomes. In conclusion, modifications of the gut microbiota by fecal microbiota transplantation or application of probiotic compounds represent potential adjunct options for immunotherapy in cancer patients which needs to be further addressed in future trials to provide individually tailored and safe adjuvant therapeutic measures in the combat of cancer.

Strategies to prevent, curb and eliminate biofilm formation based on the characteristics of various periods in one biofilm life cycle

Biofilms are colonies of bacteria embedded inside a complicated self-generating intercellular. The formation and scatter of a biofilm is an extremely complex and progressive process in constant cycles. Once formed, it can protect the inside bacteria to exist and reproduce under hostile conditions by establishing tolerance and resistance to antibiotics as well as immunological responses. In this article, we reviewed a series of innovative studies focused on inhibiting the development of biofilm and summarized a range of corresponding therapeutic methods for biological evolving stages of biofilm. Traditionally, there are four stages in the biofilm formation, while we systematize the therapeutic strategies into three main periods precisely:(i) period of preventing biofilm formation: interfering the colony effect, mass transport, chemical bonds and signaling pathway of plankton in the initial adhesion stage; (ii) period of curbing biofilm formation:targeting several pivotal molecules, for instance, polysaccharides, proteins, and extracellular DNA (eDNA) via polysaccharide hydrolases, proteases, and DNases respectively in the second stage before developing into irreversible biofilm; (iii) period of eliminating biofilm formation: applying novel multifunctional composite drugs or nanoparticle materials cooperated with ultrasonic (US), photodynamic, photothermal and even immune therapy, such as adaptive immune activated by stimulated dendritic cells (DCs), neutrophils and even immunological memory aroused by plasmocytes. The multitargeted or combinational therapies aim to prevent it from developing to the stage of maturation and dispersion and eliminate biofilms and planktonic bacteria simultaneously.

Extremely small and incredibly close: Gut microbes as modulators of inflammation and targets for therapeutic intervention

Chronic inflammation is a hallmark for a variety of disorders and is at least partially responsible for disease progression and poor patient health. In recent years, the microbiota inhabiting the human gut has been associated with not only intestinal inflammatory diseases but also those that affect the brain, liver, lungs, and joints. Despite a strong correlation between specific microbial signatures and inflammation, whether or not these microbes are disease markers or disease drivers is still a matter of debate. In this review, we discuss what is known about the molecular mechanisms by which the gut microbiota can modulate inflammation, both in the intestine and beyond. We identify the current gaps in our knowledge of biological mechanisms, discuss how these gaps have likely contributed to the uncertain outcome of fecal microbiota transplantation and probiotic clinical trials, and suggest how both mechanistic insight and -omics-based approaches can better inform study design and therapeutic intervention.

The landscape in the gut microbiome of long-lived families reveals new insights on longevity and aging - relevant neural and immune function

Human longevity has a strong familial and genetic component. Dynamic characteristics of the gut microbiome during aging associated with longevity, neural, and immune function remained unknown. Here, we aim to reveal the synergistic changes in gut microbiome associated with decline in neural and immune system with aging and further obtain insights into the establishment of microbiome homeostasis that can benefit human longevity. Based on 16S rRNA and metagenomics sequencing data for 32 longevity families including three generations, centenarians, elderly, and young groups, we found centenarians showed increased diversity of gut microbiota, severely damaged connection among bacteria, depleted in microbial-associated essential amino acid function, and increased abundance of anti-inflammatory bacteria in comparison to young and elderly groups. Some potential probiotic species, such as Desulfovibrio piger, Gordonibacter pamelaeae, Odoribacter splanchnicus, and Ruminococcaceae bacterium D5 were enriched with aging, which might possibly support health maintenance. The level of Amyloid-β (Aβ) and brain-derived neurotrophic factor (BDNF) related to neural function showed increased and decreased with aging, respectively. The elevated level of inflammatory factors was observed in centenarians compared with young and elderly groups. The enriched Bacteroides fragilis in centenarians might promote longevity through up-regulating anti-inflammatory factor IL-10 expression to mediate the critical balance between health and disease. Impressively, the associated analysis for gut microbiota with the level of Aβ, BDNF, and inflammatory factors suggests Bifidobacterium pseudocatenulatum could be a particularly beneficial bacteria in the improvement of impaired neural and immune function. Our results provide a rationale for targeting the gut microbiome in future clinical applications of aging-related diseases and extending life span.Abbreviations: 16S rRNA: 16S ribosomal RNA; MAGs: Metagenome-assembled genomes; ASVs: Amplicon sequence variants; DNA: Deoxyribonucleic acid; FDR: False discovery rate: KEGG: Kyoto Encyclopedia of Genes and Genomes; PCoA: Principal coordinates analysis; PCR: Polymerase chain reaction; PICRUSt: Phylogenetic Investigation of Communities by Reconstruction of Unobserved States; Aβ: Amyloid-β (Aβ); BDNF: Brain-derived neurotrophic factor.

Gut microbiome changes in anti-N-methyl-D-aspartate receptor encephalitis patients

Background

Anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis is a type of autoimmune encephalitis. The underlying mechanism(s) remain largely unknown. Recent evidence has indicated that the gut microbiome may be involved in neurological immune diseases via the "gut-brain axis". This study aimed to explore the possible relationship between anti-NMDAR encephalitis and the gut microbiome.

Methods

Fecal specimens were collected from 10 patients with anti-NMDAR encephalitis and 10 healthy volunteers. The microbiome analysis was based on Illumina sequencing of the V3-V4 hypervariable region of the 16S rRNA gene. The alpha, beta, and taxonomic diversity analyses were mainly based on the QIIME2 pipeline.

Results

There were no statistical differences in epidemiology, medication, and clinical characteristics (except for those related to anti-NMDAR encephalitis) between the two groups. ASV analysis showed that Prevotella was significantly increased, while Bacteroides was reduced in the gut microbiota of the patients, compared with the controls. Alpha diversity results showed a decrease in diversity in the patients compared with the healthy controls, analyzed by the Shannon diversity, Simpson diversity, and Pielou_E uniformity based on the Kruskal–Wallis test (P = 0.0342, 0.0040, and 0.0002, respectively). Beta diversity analysis showed that the abundance and composition of the gut microbiota was significantly different between the two groups, analyzed by weighted and unweighted UniFrac distance (P = 0.005 and 0.001, respectively).

Conclusions

The abundance and evenness of bacterial distribution were significantly lower and jeopardized in patients with anti-NMDAR encephalitis than in healthy controls. Thus, our findings suggest that gut microbiome composition changes might be associated with the anti-NMDAR encephalitis. It could be a causal agent, or a consequence.

The intestinal microbial metabolite nicotinamide n-oxide prevents herpes simplex encephalitis via activating mitophagy in microglia

Herpes simplex encephalitis (HSE), a complication of herpes simplex virus type I (HSV-1) infection causes neurological disorder or even death in immunocompromised adults and newborns. However, the intrinsic factors controlling the HSE outcome remain unclear. Here, we show that HSE mice exhibit gut microbiota dysbiosis and altered metabolite configuration and tryptophan-nicotinamide metabolism. HSV-1 neurotropic infection activated microglia, with changed immune properties and cell numbers, to stimulate antiviral immune response and contribute substantially to HSE. In addition, depletion of gut microbiota by oral antibiotics (ABX)-treatment triggered the hyper-activation of microglia, which in turn enhanced inflammatory immune response, and cytokine production, resulting in aggregated viral burden and HSE pathology. Furthermore, exogenous administration of nicotinamide n-oxide (NAMO), an oxidative product of nicotinamide derived from gut microbiota, to ABX-treated or untreated HSE mice significantly diminished microglia-mediated proinflammatory response and limited HSV-1 infection in CNS. Mechanistic study revealed that HSV-1 activates microglia by increasing mitochondrial damage via defective mitophagy, whereas microbial metabolite NAMO restores NAD+-dependent mitophagy to inhibit microglia activation and HSE progression. NAMO also prevented neuronal cell death triggered by HSV-1 infection or microglia-mediated microenvironmental toxicity. Finally, we show that NAMO is mainly generated by neomycin-sensitive bacteria, especially Lactobacillus_gasseri and Lactobacillus_reuteri. Together, these data demonstrate that gut microbial metabolites act as intrinsic restrictive factors against HSE progression via regulating mitophagy in microglia, implying further exploration of bacterial or nutritional approaches for treating neurotropic virus-related neurodegenerative diseases.

Understanding Immune Responses to Viruses-Do Underlying Th1/Th2 Cell Biases Predict Outcome?

Emerging and re-emerging viral diseases have increased in number and geographical extent during the last decades. Examples include the current COVID-19 pandemic and the recent epidemics of the Chikungunya, Ebola, and Zika viruses. Immune responses to viruses have been well-characterised within the innate and adaptive immunity pathways with the outcome following viral infection predominantly attributed to properties of the virus and circumstances of the infection. Perhaps the belief that the immune system is often considered as a reactive component of host defence, springing into action when a threat is detected, has contributed to a poorer understanding of the inherent differences in an individual's immune system in the absence of any pathology. In this review, we focus on how these host factors (age, ethnicity, underlying pathologies) may skew the T helper cell response, thereby influencing the outcome following viral infection but also whether we can use these inherent biases to predict patients at risk of a deviant response and apply strategies to avoid or overcome them.

Role of the gut microbiome in multiple sclerosis: From etiology to therapeutics

Multiple sclerosis (MS) is a chronic inflammatory disease of the CNS that affects around one million people in the United States. Predisposition or protection from this disease is linked with both genetic and environmental factors. In recent years, gut microbiome has emerged as an important environmental factor in the pathobiology of MS. The gut microbiome supports various physiologic functions, including the development and maintenance of the host immune system, the perturbation of which is known as dysbiosis and has been linked with multiple diseases including MS. We and others have shown that people with MS (PwMS) have gut dysbiosis that is characterized by specific gut bacteria being enriched or depleted. Consequently, there is an emphasis on determining the mechanism(s) through which gut bacteria and/or their metabolites alter the course of MS through their ability to provide protection, predispose individuals, or promote disease progression. Improving our understanding of these mechanisms will allow us to harness the enormous potential of the gut microbiome as a diagnostic and/or therapeutic agent. In this chapter, we will discuss current advances in microbiome research in the context of MS, including a review of specific bacteria that are currently linked with this disease, potential mechanisms of disease pathogenesis, and the utility of microbiome-based therapy for PwMS.

IL‑10/IL‑10 receptor 1 pathway promotes the viability and collagen synthesis of pulmonary fibroblasts originated from interstitial pneumonia tissues

Interstitial pneumonia is a pulmonary interstitial inflammatory and fibrosis disease with a variety of causes that causes respiratory disorders and threatens the lives of patients. The present study aimed to investigate the expression of interleukin (IL)-10 in peripheral blood of patients with interstitial pneumonia and its biological functions in pulmonary fibroblasts. A total of 42 patients with idiopathic pulmonary fibrosis (IPF) and 20 healthy subjects were included. ELISA was used to determine IL-10 concentration in serum from the patients and healthy subjects. Primary fibroblasts were isolated from lung tissue successfully and determined by morphology. The CCK-8 assay was performed to determine the effect of IL-10 expression on cell viability. Western blotting was used to determine COL1a1, COL1a2 and IL-10R1 protein expression. Flow cytometry was used for cell cycle analysis and to determine the number of IL-10⁺ cells. Expression of IL-10 in serum from IPF patients was higher compared to that from healthy subjects. IL-10 promoted the viability and collagen synthesis and secretion of MRC-5 cells and primary pulmonary fibroblasts. IL-10 and IL-10 receptor (R) 1 served regulatory roles in the viability and collagen synthesis of MRC-5 cells. The ratio of peripheral mononuclear lymphocytes with positive expression of IL-10 was elevated in peripheral blood from patients with IPF. The present study demonstrated that IL-10 expression in peripheral blood of patients with IPF is increased significantly compared with healthy subjects. Activation of the IL-10/IL-10R1 signaling pathway promoted the viability and collagen synthesis and secretion of pulmonary fibroblasts, leading to pulmonary fibrosis. The present study provided experimental basis for further understanding the development mechanism of pulmonary fibrosis.