Control of lymphocyte functions by gut microbiota-derived short-chain fatty acids

Advances in the mechanism of action of short-chain fatty acids in psoriasis

Psoriasis is a prevalent chronic inflammatory and immunological disorder. Its lesions are present as scaly erythema or plaques. Disruptions in the body's immune system play a significant role in developing psoriasis. Recent evidence suggests a potential role of the gut microbiome in autoimmune diseases. Short-chain fatty acids (SCFAs) are the primary metabolites created by gut microbes and play a crucial fuction in autoimmunity. SCFAs act on various cells by mediating signaling to participate in host physiological and pathological processes. These processes encompass body metabolism, maintenance of intestinal barrier function, and immune system modulation. SCFAs can regulate immune cells to enhance the body's immune function, potentially influencing the prevention and treatment of psoriasis. However, the mechanisms underlying the role of SCFAs in psoriasis remain incompletely understood. This paper examines the relationship between SCFAs and psoriasis, elucidating how SCFAs influence the immune system, inflammatory response, and gut barrier in psoriasis. According to the study, in psoriasis, SCFAs have been shown to regulate neutrophils, macrophages, and dendritic cells in the adaptive immune system, as well as T and B cells in the innate immune system. Additionally, we explore the role of SCFAs in psoriasis by maintaining intestinal barrier function, restoring intestinal ecological homeostasis, and investigating the potential therapeutic benefits of SCFAs for psoriasis.

Lactobacillus murinus alleviated lung inflammation induced by PAHs in mice

OBJECTIVE

This study aimed to investigate the mechanism that Lactobacillus murinus (L. murinus) alleviated lung inflammation induced by polycyclic aromatic hydrocarbons (PAHs) exposure based on metabolomics.

METHODS

Female mice were administrated with PAHs mix, L. murinus and indoleacrylic acid (IA) or indolealdehyde (IAId). Microbial diversity in feces was detected by 16 S rRNA gene sequencing. Non-targeted metabolomics analysis in urine samples and targeted analysis of tryptophan metabolites in serum by UPLC-Orbitrap-MS and short-chain fatty acids (SCFA) in feces by GC-MS were performed, respectively. Flow cytometry was used to determine T helper immune cell differentiation in gut and lung tissues. The levels of IgE, IL-4 and IL-17A in the bronchoalveolar lavage fluid (BALF) or serum were detected by ELISA. The expressions of aryl hydrocarbon receptor (Ahr), cytochrome P450 1A1 (Cyp1a1) and forkheadbox protein 3 (Foxp3) genes and the histone deacetylation activity were detected by qPCR and by ELISA in lung tissues, respectively.

RESULTS

PAHs exposure induced lung inflammation and microbial composition shifts and tryptophan metabolism disturbance in mice. L. murinus alleviated PAHs-induced lung inflammation and inhibited T helper cell 17 (Th17) cell differentiation and promoted regulatory T cells (Treg) cell differentiation. L. murinus increased the levels of IA and IAId in the serum and regulated Th17/Treg imbalance by activating AhR. Additionally, L. murinus restored PAHs-induced decrease of butyric acid and valeric acid which can reduce the histone deacetylase (HDAC) level in the lung tissues, enhancing the expression of the Foxp3 gene and promoting Treg cell differentiation.

CONCLUSION

our study illustrated that L. murinus alleviated PAHs-induced lung inflammation and regulated Th17/Treg cell differentiation by regulating host tryptophan metabolism and SCFA levels. The study provided new insights into the reciprocal influence between gut microbiota, host metabolism and the immune system, suggesting that L. murinus might have the potential as a novel therapeutic strategy for lung diseases caused by environmental pollution in the future.

The roles of dietary polyphenols at crosstalk between type 2 diabetes and Alzheimer's disease in ameliorating oxidative stress and mitochondrial dysfunction via PI3K/Akt signaling pathways

Alzheimer's disease (AD) is a fatal neurodegenerative disease in which senile plaques and neurofibrillary tangles are crucially involved in its physiological and pathophysiological processes. Growing animal and clinical studies have suggested that AD is also comorbid with some metabolic diseases, including type 2 diabetes mellitus (T2DM), and therefore, it is often considered brain diabetes. AD and T2DM share multiple molecular and biochemical mechanisms, including impaired insulin signaling, oxidative stress, gut microbiota dysbiosis, and mitochondrial dysfunction. In this review article, we mainly introduce oxidative stress and mitochondrial dysfunction and explain their role and the underlying molecular mechanism in T2DM and AD pathogenesis; then, according to the current literature, we comprehensively evaluate the possibility of regulating oxidative homeostasis and mitochondrial function as therapeutics against AD. Furthermore, considering dietary polyphenols' antioxidative and antidiabetic properties, the strategies for applying them as potential therapeutical interventions in patients with AD symptoms are assessed.

Functional foods lipids: unraveling their role in the immune response in obesity

Functional lipids are lipids that are found in food matrices and play an important role in influencing human health as their role goes beyond energy storage and structural components. Ongoing research into functional lipids has highlighted their potential to modulate immune responses and other mechanisms associated with obesity, along with its comorbidities. These lipids represent a new field that may offer new therapeutic and preventive strategies for these diseases by understanding their contribution to health. In this review, we discussed in-depth the potential food sources of functional lipids and their reported potential benefit of the major lipid classification: based on their composition such as simple, compound, and derived lipids, and based on their function such as storage and structural, by investigating the intricate mechanisms through which these lipids interact in the human body. We summarize the key insights into the bioaccessibility and bioavailability of the most studied functional lipids. Furthermore, we review the main immunomodulatory mechanisms reported in the literature in the past years. Finally, we discuss the perspectives and challenges faced in the food industry related to functional lipids.

OLFM4 modulates intestinal inflammation by promoting IL-22+ILC3 in the gut

Group 3 innate lymphoid cells (ILC3s) play key roles in intestinal inflammation. Olfactomedin 4 (OLFM4) is highly expressed in the colon and has a potential role in dextran sodium sulfate-induced colitis. However, the detailed mechanisms underlying the effects of OLFM4 on ILC3-mediated colitis remain unclear. In this study, we identify OLFM4 as a positive regulator of IL-22+ILC3. OLFM4 expression in colonic ILC3s increases substantially during intestinal inflammation in humans and mice. Compared to littermate controls, OLFM4-deficient (OLFM4-/-) mice are more susceptible to bacterial infection and display greater resistance to anti-CD40 induced innate colitis, together with impaired IL-22 production by ILC3, and ILC3s from OLFM4-/-mice are defective in pathogen resistance. Besides, mice with OLFM4 deficiency in the RORγt compartment exhibit the same trend as in OLFM4-/-mice, including colonic inflammation and IL-22 production. Mechanistically, the decrease in IL-22+ILC3 caused by OLFM4 deficiency involves the apoptosis signal-regulating kinase 1 (ASK1)- p38 MAPK signaling-dependent downregulation of RAR-related orphan receptor gamma (RORγt) protein. The OLFM4-metadherin (MTDH) complex upregulates p38/RORγt signaling, which is necessary for IL-22+ILC3 activation. The findings indicate that OLFM4 is a novel regulator of IL-22+ILC3 and essential for modulating intestinal inflammation and tissue homeostasis.

The Role of Intestinal Microbiota and Probiotics Supplementation in Multiple Sclerosis Management

Multiple sclerosis (MS) is a neurological autoimmune disorder predominantly afflicting young adults. The etiology of MS is intricate, involving a variety of environmental and genetic factors. Current research increasingly focuses on the substantial contribution of gut microbiota in MS pathogenesis. The commensal microbiota resident within the intestinal milieu assumes a central role within the intricate network recognized as the gut-brain axis (GBA), wielding beneficial impact in neurological and psychological facets. As a result, the modulation of gut microbiota is considered a pivotal aspect in the management of neural disorders, including MS. Recent investigations have unveiled the possibility of using probiotic supplements as a promising strategy for exerting a positive impact on the course of MS. This therapeutic approach operates through several mechanisms, including the reinforcement of gut epithelial integrity, augmentation of the host's resistance against pathogenic microorganisms, and facilitation of mucosal immunomodulatory processes. The present study comprehensively explains the gut microbiome's profound influence on the central nervous system (CNS). It underscores the pivotal role played by probiotics in forming the immune system and modulating neurotransmitter function. Furthermore, the investigation elucidates various instances of probiotic utilization in MS patients, shedding light on the potential therapeutic advantages afforded by this intervention.

Protective function of sclerosing cholangitis on IBD

OBJECTIVE

There is a strong clinical association between IBD and primary sclerosing cholangitis (PSC), a chronic disease of the liver characterised by biliary inflammation that leads to strictures and fibrosis. Approximately 60%-80% of people with PSC will also develop IBD (PSC-IBD). One hypothesis explaining this association would be that PSC drives IBD. Therefore, our aim was to test this hypothesis and to decipher the underlying mechanism.

DESIGN

Colitis severity was analysed in experimental mouse models of colitis and sclerosing cholangitis, and people with IBD and PSC-IBD. Foxp3+ Treg-cell infiltration was assessed by qPCR and flow cytometry. Microbiota profiling was carried out from faecal samples of people with IBD, PSC-IBD and mouse models recapitulating these diseases. Faecal microbiota samples collected from people with IBD and PSC-IBD were transplanted into germ-free mice followed by colitis induction.

RESULTS

We show that sclerosing cholangitis attenuated IBD in mouse models. Mechanistically, sclerosing cholangitis causes an altered intestinal microbiota composition, which promotes Foxp3+ Treg-cell expansion, and thereby protects against IBD. Accordingly, sclerosing cholangitis promotes IBD in the absence of Foxp3+ Treg cells. Furthermore, people with PSC-IBD have an increased Foxp3+ expression in the colon and an overall milder IBD severity. Finally, by transplanting faecal microbiota into gnotobiotic mice, we showed that the intestinal microbiota of people with PSC protects against colitis.

CONCLUSION

This study shows that PSC attenuates IBD and provides a comprehensive insight into the mechanisms involved in this effect.

Gut microbiota-derived metabolites tune host homeostasis fate

The gut microbiota, housing trillions of microorganisms within the gastrointestinal tract, has emerged as a critical regulator of host health and homeostasis. Through complex metabolic interactions, these microorganisms produce a diverse range of metabolites that substantially impact various physiological processes within the host. This review aims to delve into the intricate relationships of gut microbiota-derived metabolites and their influence on the host homeostasis. We will explore how these metabolites affect crucial aspects of host physiology, including metabolism, mucosal integrity, and communication among gut tissues. Moreover, we will spotlight the potential therapeutic applications of targeting these metabolites to restore and sustain host equilibrium. Understanding the intricate interplay between gut microbiota and their metabolites is crucial for developing innovative strategies to promote wellbeing and improve outcomes of chronic diseases.

Proteobacteria impair anti-tumor immunity in the omentum by consuming arginine

Gut microbiota influence anti-tumor immunity, often by producing immune-modulating metabolites. However, microbes consume a variety of metabolites that may also impact host immune responses. We show that tumors grow unchecked in the omenta of microbe-replete mice due to immunosuppressive Tregs. By contrast, omental tumors in germ-free, neomycin-treated mice or mice colonized with altered Schaedler's flora (ASF) are spontaneously eliminated by CD8+ T cells. These mice lack Proteobacteria capable of arginine catabolism, causing increases in serum arginine that activate the mammalian target of the rapamycin (mTOR) pathway in Tregs to reduce their suppressive capacity. Transfer of the Proteobacteria, Escherichia coli (E. coli), but not a mutant unable to catabolize arginine, to ASF mice reduces arginine levels, restores Treg suppression, and prevents tumor clearance. Supplementary arginine similarly decreases Treg suppressive capacity, increases CD8+ T cell effectiveness, and reduces tumor burden. Thus, microbial consumption of arginine alters anti-tumor immunity, offering potential therapeutic strategies for tumors in visceral adipose tissue.

Non-SCFA microbial metabolites associated with fiber fermentation and host health

Dietary fiber is degraded by commensal gut microbes to yield host-beneficial short-chain fatty acids (SCFAs), but personalized responses to fiber supplementation highlight a role for other microbial metabolites in shaping host health. In this review we summarize recent findings from dietary fiber intervention studies describing health impacts attributed to microbial metabolites other than SCFAs, particularly secondary bile acids (2°BAs), aromatic amino acid derivatives, neurotransmitters, and B vitamins. We also discuss shifts in microbial metabolism occurring through altered maternal dietary fiber intake and agricultural practices, which warrant further investigation. To optimize the health benefits of dietary fibers, it is essential to survey a range of metabolites and adapt recommendations on a personalized basis, according to the different functional aspects of the microbiome.

A synbiotic of Anaerostipes caccae and lactulose prevents and treats food allergy in mice

Depletion of beneficial microbes by modern lifestyle factors correlates with the rising prevalence of food allergies. Re-introduction of allergy-protective bacteria may be an effective treatment strategy. We characterized the fecal microbiota of healthy and food-allergic infants and found that the anaerobe Anaerostipes caccae (A. caccae) was representative of the protective capacity of the healthy microbiota. We isolated a strain of A. caccae from the feces of a healthy infant and identified lactulose as a prebiotic to optimize butyrate production by A. caccae in vitro. Administration of a synbiotic composed of our isolated A. caccae strain and lactulose increased luminal butyrate in gnotobiotic mice colonized with feces from an allergic infant and in antibiotic-treated specific pathogen-free (SPF) mice, and prevented or treated an anaphylactic response to allergen challenge. The synbiotic's efficacy in two models and microbial contexts suggests that it may be a promising approach for the treatment of food allergy.

Healthy eating index 2015 might be associated with migraine headaches: Results from a Case-Control study

Migraine headaches are the most prevalent disabling primary headaches, affecting individuals at an active age. Dietary interventions are considered low-cost and practical approaches to migraine prophylaxis. Hence, the present study aimed to assess the association between adherence to the Healthy Eating Index 2015 (HEI-2015) and migraine headaches. The present case-control study was conducted on 476 newly diagnosed adults with migraine headaches, based on the International Classification of Headache Disorders 3rd edition (ICHDIII criteria(, and 512 healthy controls. Participants' dietary intakes were collected using a validated, 168-item semi-quantitative food frequency questionnaire (FFQ). The association between HEI-2015 and migraine headaches was assessed using logistic regression models. Although the trend was not statistically significant, being in the 4th quantile of the HEI-2015 was associated with about 50% lower odds of migraine headaches in both primary (adjusted for age and gender) (odds ratios (OR): 0.51, 95% confidence intervals (CI): 0.33, 0.78) and fully adjusted models (additionally adjusted for body mass index (BMI) and total calories) (adjusted OR: 0.50, 95%CI: 0.32, 0.77). Intriguingly, the odds of migraine headaches were significantly higher in those in the last quantile of "Total Fruits," which is equal to more than 237 g per 1000 kcal (aOR: 2.96, 95%CI: 1.99, 4.41) and "Whole Fruits," which is equal to more than 233 g per 1000 kcal (aOR: 2.90, 95%CI: 1.94, 4.31). Similarly, higher intakes of "Dairy," which is equal to more than 138 g per 1000 kcal (aOR: 2.66, 95%CI: 1.71, 4.14), and "Total Protein Foods," which is equal to more than 259 g per 1000 kcal (aOR: 2.41, 95%CI: 1.58, 3.70), were associated with higher odds of migraine headaches. The current study revealed an indirect association between HEI-2015 and its components, including "Greens and Beans," "Whole Grains," "Refined Grains," and "Added Sugars" and lower odds of migraine headaches.

Molecular mechanisms of gut microbiota in diabetic nephropathy

Diabetic nephropathy is a common complication of diabetes and a considerable contributor to end-stage renal disease. Evidence indicates that glucose dysregulation and lipid metabolism comprise a pivotal pathogenic mechanism in diabetic nephropathy. However, current treatment outcomes are limited, as they only provide symptomatic relief without preventing disease progression. The gut microbiota is a group of microorganisms that inhabit the human intestinal tract and play a crucial role in maintaining host energy balance, metabolism, and immune activity. Patients with diabetic nephropathy exhibit altered gut microbiota, suggesting its potential involvement in the onset and progression of the disease. However, how a perturbed microbiota induces and promotes diabetic nephropathy remains unelucidated. This article summarizes the evidence of the impact of gut microbiota on the progression of diabetic nephropathy, with a particular focus on the molecular mechanisms involved, aiming to provide new insights into the treatment of diabetic nephropathy.

Metabolic dysregulation of lymphocytes in autoimmune diseases

Lymphocytes are crucial for protective immunity against infection and cancers; however, immune dysregulation can lead to autoimmune diseases such as systemic lupus erythematosus (SLE) and rheumatoid arthritis (RA). Metabolic adaptation controls lymphocyte fate; thus, metabolic reprogramming can contribute to the pathogenesis of autoimmune diseases. Here, we summarize recent advances on how metabolic reprogramming determines the autoreactive and proinflammatory nature of lymphocytes in SLE and RA, unraveling molecular mechanisms and providing therapeutic targets for human autoimmune diseases.

Immunometabolites in viral infections: Action mechanism and function

The interplay between viral pathogens and host metabolism plays a pivotal role in determining the outcome of viral infections. Upon viral detection, the metabolic landscape of the host cell undergoes significant changes, shifting from oxidative respiration via the tricarboxylic acid (TCA) cycle to increased aerobic glycolysis. This metabolic shift is accompanied by elevated nutrient accessibility, which is vital for cell function, development, and proliferation. Furthermore, depositing metabolites derived from fatty acids, TCA intermediates, and amino acid catabolism accelerates the immunometabolic transition, facilitating pro-inflammatory and antimicrobial responses. Immunometabolites refer to small molecules involved in cellular metabolism regulating the immune response. These molecules include nutrients, such as glucose and amino acids, along with metabolic intermediates and signaling molecules adenosine, lactate, itaconate, succinate, kynurenine, and prostaglandins. Emerging evidence suggests that immunometabolites released by immune cells establish a complex interaction network within local niches, orchestrating and fine-tuning immune responses during viral diseases. However, our current understanding of the immense capacity of metabolites to convey essential cell signals from one cell to another or within cellular compartments remains incomplete. Unraveling these complexities would be crucial for harnessing the potential of immunometabolites in therapeutic interventions. In this review, we discuss specific immunometabolites and their mechanisms of action in viral infections, emphasizing recent findings and future directions in this rapidly evolving field.

G-protein-coupled receptor 84 regulates acute inflammation in normal and diabetic skin wounds

Lipids have emerged as potent regulators of immune cell function. In the skin, adipocyte lipolysis increases the local pool of free fatty acids and is essential for coordinating early macrophage inflammation following injury. Here, we investigate G-protein-coupled receptor 84 (GPR84), a medium-chain fatty acid (MCFA) receptor, for its potential to propagate pro-inflammatory signaling after skin injury. GPR84 signaling was identified as a key component of regulating myeloid cell numbers and subsequent tissue repair through in vivo administration of a pharmacological antagonist and the MCFA decanoic acid. We found that impaired injury-induced dermal adipocyte lipolysis is a hallmark of diabetes, and lipidomic analysis demonstrated that MCFAs are significantly reduced in diabetic murine wounds. Furthermore, local administration of decanoic acid rescued myeloid cell numbers and tissue repair during diabetic wound healing. Thus, GPR84 is a readily targetable lipid signaling pathway for manipulating injury-induced tissue inflammation with beneficial effects on acute diabetic healing.

Dietary risk factors for colorectal cancer in Uganda: a case-control study

INTRODUCTION

Low-income countries in East Africa have a lower incidence of colorectal cancer (CRC) than high-income countries; however, the incidence has steadily increased in the last few decades. In Uganda, the extent to which genetic and environmental factors, particularly dietary factors, contribute to the aetiology of CRC is unclear. Therefore, the objective of our study was to determine the relationship between dietary factors and CRC in Uganda.

METHODS

We conducted a case-control study and recruited 128 cases and 256 controls, matched for age (± 5 years) and sex. Data regarding the frequency of consumption of the dietary factors were obtained from all the participants using an interview-based questionnaire. The potential dietary risk factors and protective factors evaluated included the type and frequency of meat consumed and the type and frequency of high-fibre foods consumed. The frequency was either 4 or more times/week, 2-3 times/week, once/week or never. Conditional logistic regression analyses were used to determine the odds ratios associated with the different risk and protective factors.

RESULTS

The median age (IQR) for the case participants was 55.5 (43-67.5) years, and that of the control participants was 54 (42-65) years. The male-to-female ratio was 1:1 for all the participants. Factors significantly associated with CRC cases included:- the consumption of boiled beef 2-3 times/week (aOR:3.24; 95% CI: 1.08-9.69; p < 0.035). Consumption of high-fibre foods, including:- millet for ≥ 4 times/week (aOR: 0.23; 95% CI: 0.09-0.62; p = 0.003)), spinach for ≥ 4 times/week (aOR:0.32; 95% CI: 0.11-0.97; p = 0.043), and potatoes 2-3 times/week (aOR: 0.30; 95% CI: 0.09-0.97; p = 0.044), were protective against CRC. Boiled cassava showed a tendency to reduce the likelihood of CRC when consumed ≥ 4 times/week (aOR:0.38; 95% CI: 0.12-1.18) however this did not reach statistical significance (p = 0.093).

CONCLUSIONS

The consumption of boiled beef increases the risk of CRC, while the intake of high-fibre foods may reduce the risk of CRC among Ugandans. We recommend nutritional educational programmes to increase public awareness regarding the protective role of a high-fibre diet and to limit the intake of cooked meat in our Ugandan population.

Spatial Distribution and Functional Impact of Human Scalp Hair Follicle Microbiota

Human hair follicles (HFs) constitute a unique microbiota habitat that differs substantially from the skin surface. Traditional HF sampling methods fail to eliminate skin microbiota contaminants or assess the HF microbiota incompletely, and microbiota functions in human HF physiology remain ill explored. Therefore, we used laser-capture microdissection, metagenomic shotgun sequencing, and FISH to characterize the human scalp HF microbiota in defined anatomical compartments. This revealed significant compartment-, tissue lineage-, and donor age-dependent variations in microbiota composition. Greatest abundance variations between HF compartments were observed for viruses, archaea, Staphylococcus epidermidis, Cutibacterium acnes, and Malassezia restricta, with the latter 2 being the most abundant viable HF colonizers (as tested by propidium monoazide assay) and, surprisingly, most abundant in the HF mesenchyme. Transfection of organ-cultured human scalp HFs with S. epidermidis-specific lytic bacteriophages ex vivo downregulated transcription of genes known to regulate HF growth and development, metabolism, and melanogenesis, suggesting that selected microbial products may modulate HF functions. Indeed, HF treatment with butyrate, a metabolite of S. epidermidis and other HF microbiota, delayed catagen and promoted autophagy, mitochondrial activity, and gp100 and dermcidin expression ex vivo. Thus, human HF microbiota show spatial variations in abundance and modulate the physiology of their host, which invites therapeutic targeting.

Therapeutic Potential of Fungal Polysaccharides in Gut Microbiota Regulation: Implications for Diabetes, Neurodegeneration, and Oncology

This review evaluates the therapeutic effects of polysaccharides derived from mushroom species that have medicinal and edible properties. The fungal polysaccharides were recently studied, focusing on their modulation of the gut microbiota and their impact on various diseases. The study covers both clinical and preclinical studies, detailing the results and highlighting the significant influence of these polysaccharides on gut microbiota modulation. It discusses the potential health benefits derived from incorporating these polysaccharides into the diet for managing chronic diseases such as diabetes, neurodegenerative disorders, and cancer. Furthermore, the review emphasizes the interaction between fungal polysaccharides and the gut microbiota, underscoring their role in modulating the gut microbial community. It presents a systematic analysis of the findings, demonstrating the substantial impact of fungal polysaccharides on gut microbiota composition and function, which may contribute to their therapeutic effects in various chronic conditions. We conclude that the modulation of the gut microbiota by these polysaccharides may play a crucial role in mediating their therapeutic effects, offering a promising avenue for further research and potential applications in disease prevention and treatment.

Gut microbial metabolite targets HDAC3-FOXK1-interferon axis in fibroblast-like synoviocytes to ameliorate rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease. Early studies hold an opinion that gut microbiota is environmentally acquired and associated with RA susceptibility. However, accumulating evidence demonstrates that genetics also shape the gut microbiota. It is known that some strains of inbred laboratory mice are highly susceptible to collagen-induced arthritis (CIA), while the others are resistant to CIA. Here, we show that transplantation of fecal microbiota of CIA-resistant C57BL/6J mice to CIA-susceptible DBA/1J mice confer CIA resistance in DBA/1J mice. C57BL/6J mice and healthy human individuals have enriched B. fragilis than DBA/1J mice and RA patients. Transplantation of B. fragilis prevents CIA in DBA/1J mice. We identify that B. fragilis mainly produces propionate and C57BL/6J mice and healthy human individuals have higher level of propionate. Fibroblast-like synoviocytes (FLSs) in RA are activated to undergo tumor-like transformation. Propionate disrupts HDAC3-FOXK1 interaction to increase acetylation of FOXK1, resulting in reduced FOXK1 stability, blocked interferon signaling and deactivation of RA-FLSs. We treat CIA mice with propionate and show that propionate attenuates CIA. Moreover, a combination of propionate with anti-TNF etanercept synergistically relieves CIA. These results suggest that B. fragilis or propionate could be an alternative or complementary approach to the current therapies.

The microbiota-gut-brain-immune interface in the pathogenesis of neuroinflammatory diseases: a narrative review of the emerging literature

Importance

Research is beginning to elucidate the sophisticated mechanisms underlying the microbiota-gut-brain-immune interface, moving from primarily animal models to human studies. Findings support the dynamic relationships between the gut microbiota as an ecosystem (microbiome) within an ecosystem (host) and its intersection with the host immune and nervous systems. Adding this to the effects on epigenetic regulation of gene expression further complicates and strengthens the response. At the heart is inflammation, which manifests in a variety of pathologies including neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease, and Multiple Sclerosis (MS).

Observations

Generally, the research to date is limited and has focused on bacteria, likely due to the simplicity and cost-effectiveness of 16s rRNA sequencing, despite its lower resolution and inability to determine functional ability/alterations. However, this omits all other microbiota including fungi, viruses, and phages, which are emerging as key members of the human microbiome. Much of the research has been done in pre-clinical models and/or in small human studies in more developed parts of the world. The relationships observed are promising but cannot be considered reliable or generalizable at this time. Specifically, causal relationships cannot be determined currently. More research has been done in Alzheimer's disease, followed by Parkinson's disease, and then little in MS. The data for MS is encouraging despite this.

Conclusions and relevance

While the research is still nascent, the microbiota-gut-brain-immune interface may be a missing link, which has hampered our progress on understanding, let alone preventing, managing, or putting into remission neurodegenerative diseases. Relationships must first be established in humans, as animal models have been shown to poorly translate to complex human physiology and environments, especially when investigating the human gut microbiome and its relationships where animal models are often overly simplistic. Only then can robust research be conducted in humans and using mechanistic model systems.

Review: A Contemporary, Multifaced Insight into Psoriasis Pathogenesis

Psoriasis is a chronic recurrent inflammatory autoimmune pathology with a significant genetic component and several interferences of immunological cells and their cytokines. The complex orchestration of psoriasis pathogenesis is related to the synergic effect of immune cells, polygenic alterations, autoantigens, and several other external factors. The major act of the IL-23/IL-17 axis, strongly influencing the inflammatory pattern established during the disease activity, is visible as a continuous perpetuation of the pro-inflammatory response and keratinocyte activation and proliferation, leading to the development of psoriatic lesions. Genome-wide association studies (GWASs) offer a better view of psoriasis pathogenic pathways, with approximately one-third of psoriasis's genetic impact on psoriasis development associated with the MHC region, with genetic loci located on chromosome 6. The most eloquent genetic factor of psoriasis, PSORS1, was identified in the MHC I site. Among the several factors involved in its complex etiology, dysbiosis, due to genetic or external stimulus, induces a burst of pro-inflammatory consequences; both the cutaneous and gut microbiome get involved in the psoriasis pathogenic process. Cutting-edge research studies and comprehensive insights into psoriasis pathogenesis, fostering novel genetic, epigenetic, and immunological factors, have generated a spectacular improvement over the past decades, securing the path toward a specific and targeted immunotherapeutic approach and delayed progression to inflammatory arthritis. This review aimed to offer insight into various domains that underline the pathogenesis of psoriasis and how they influence disease development and evolution. The pathogenesis mechanism of psoriasis is multifaceted and involves an interplay of cellular and humoral immunity, which affects susceptible microbiota and the genetic background. An in-depth understanding of the role of pathogenic factors forms the basis for developing novel and individualized therapeutic targets that can improve disease management.

A Randomized Clinical Trial to Evaluate the Efficacy of an Oral Probiotic in Acne Vulgaris

The relevance of the gut microbiota in some skin inflammatory diseases, including acne vulgaris, has been emphasized. Probiotics could play a role in the modulation of the microbiota, improving the clinical course of this disease. A 12-week randomized, double-blind, placebo-controlled, clinical trial with patients aged 12 to 30 years with acne vulgaris was conducted. The study product was a capsule composed of the probiotic Lacticaseibacillus rhamnosus (CECT 30031) and the cyanobacterium Arthrospira platensis (BEA_IDA_0074B). Patients with improvement in the Acne Global Severity Scale were 10/34 (29.41%) in the placebo group compared with 20/40 (50%) in the probiotic group (p = 0.03). A significant reduction (p = 0.03) in the number of non-inflammatory acne lesions was observed in the probiotic group (-18.60 [-24.38 to -12.82]) vs the placebo group (-10.54 [-17.43 to -3.66]). Regarding the number of total  lesions, a reduction almost reaching statistical significance (p = 0.06) was observed in the probiotic group (-27.94 [-36.35 to -19.53]) compared with the placebo group (-18.31 [-28.21 to -8.41]). In addition, patients with improvement attending the Global Acne Grading System were 7/34 (20.58%) in the placebo group vs 17/40 (42.50%) in the probiotic group (p = 0.02). The number of adverse events was similar in both groups. The probiotic used in this study was effective and well tolerated, and it should be considered for acne vulgaris patients.

Combination of vitamin D3 and fructooligosaccharides upregulates colonic vitamin D receptor in C57BL/6J mice and affects anxiety-related behavior in a sex-specific manner

Depression and anxiety disorders are among the most common mental health disorders that affect US adults today, frequently related to vitamin D (VD) insufficiency. Along with VD, growing evidence suggests gut microbiota likely play a role in neuropsychiatric disorders. Here, we investigated if modulation of gut microbiota would disrupt host VD status and promote behaviors related to depression and anxiety in adult mice. Six-week-old male and female C57BL/6J mice (n = 10/mice/group) were randomly assigned to receive (1) control diet (CTR), control diet treated with antibiotics (AB), control diet with total 5000 IU of VD (VD), VD treated with antibiotics (VD + AB), VD supplemented with 5% w/w fructooligosaccharides (FOS; VF), and VF diet treated with antibiotics (VF + AB), respectively, for 8 weeks. Our study demonstrated that VD status was not affected by antibiotic regimen. VD alone ameliorates anxiety-related behavior in female mice, and that combination with FOS (i.e., VF) did not further improve the outcome. Male mice, in contrast, exhibit greater anxiety with VF, but not VD, when compared with CTR mice. Colonic VD receptor was elevated in VF-treated mice in both sexes, compared with CTR, which was positively correlated to colonic TPH1, a rate-limiting enzyme for serotonin synthesis. Taken together, our data indicate that the effect of VF on anxiety-related behavior is sex-specific, which may partially be attributed to the activation of colonic VD signaling and subsequent serotonin synthesis. The synergistic or additive effect of VD and FOS on mood disorders remained to be investigated.

Same yet different - how lymph node heterogeneity affects immune responses

Lymph nodes are secondary lymphoid organs in which immune responses of the adaptive immune system are initiated and regulated. Distributed throughout the body and embedded in the lymphatic system, local lymph nodes are continuously informed about the state of the organs owing to a constant drainage of lymph. The tissue-derived lymph carries products of cell metabolism, proteins, carbohydrates, lipids, pathogens and circulating immune cells. Notably, there is a growing body of evidence that individual lymph nodes differ from each other in their capacity to generate immune responses. Here, we review the structure and function of the lymphatic system and then focus on the factors that lead to functional heterogeneity among different lymph nodes. We will discuss how lymph node heterogeneity impacts on cellular and humoral immune responses and the implications for vaccination, tumour development and tumour control by immunotherapy.

Revisiting the Role of Valeric Acid in Manipulating Ulcerative Colitis

BACKGROUND

Ulcerative colitis (UC) is characterized by a complicated interaction between mucosal inflammation, epithelial dysfunction, abnormal activation of innate immune responses, and gut microbiota dysbiosis. Though valeric acid (VA), one type of short-chain fatty acids (SCFAs), has been identified in other inflammatory disorders and cancer development, the pathological role of VA and underlying mechanism of VA in UC remain under further investigation.

METHODS

Studies of human clinical specimens and experimental colitis models were conducted to confirm the pathological manifestations of the level of SCFAs from human fecal samples and murine colonic homogenates. Valeric acid-intervened murine colitis and a macrophage adoptive transfer were applied to identify the underlying mechanisms.

RESULTS

In line with gut microbiota dysfunction in UC, alteration of SCFAs from gut microbes were identified in human UC patients and dextran sodium sulfate -induced murine colitis models. Notably, VA was consistently negatively related to the disease severity of UC, the population of monocytes, and the level of interluekin-6. Moreover, VA treatment showed direct suppressive effects on lipopolysaccharides (LPS)-activated human peripheral blood mononuclear cells and murine macrophages in the dependent manner of upregulation of GPR41 and GPR43. Therapeutically, replenishment of VA or adoptive transfer with VA-modulated macrophages showed resistance to dextran sodium sulfate-driven murine colitis though modulating the production of inflammatory cytokine interleukin-6.

CONCLUSIONS

In summary, the research uncovered the pathological role of VA in modulating the activation of macrophages in UC and suggested that VA might be a potential effective agent for UC patients.

Immmunometabolism of systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a potentially fatal chronic autoimmune disease which is underlain by complex dysfunction of the innate and adaptive immune systems. Although a series of well-defined genetic and environmental factors have been implicated in disease etiology, neither the development nor the persistence of SLE is well understood. Given that several disease susceptibility genes and environmental factors interact and influence inflammatory lineage specification through metabolism, the field of immunometabolism has become a forefront of cutting edge research. Along these lines, metabolic checkpoints of pathogenesis have been identified as targets of effective therapeutic interventions in mouse models and validated in clinical trials. Ongoing studies focus on mitochondrial oxidative stress, activation of the mechanistic target of rapamycin, calcium signaling, glucose utilization, tryptophan degradation, and metabolic cross-talk between gut microbiota and the host immune system.

Use of a novel microbiome modulator improves anticancer immunity in a murine model of malignant pleural mesothelioma

Objective

Malignant pleural mesothelioma is a fatal disease and a clinical challenge, as few effective treatment modalities are available. Previous evidence links the gut microbiome to the host immunoreactivity to tumors. We thus evaluated the impact of a novel microbiome modulator compound (MMC) on the gut microbiota composition, tumor immune microenvironment, and cancer control in a model of malignant pleural mesothelioma.

Methods

Age- and weight-matched immunocompetent (n = 23) or athymic BALB/c mice (n = 15) were randomly assigned to MMC or no treatment (control) groups. MMC (31 ppm) was administered through the drinking water 14 days before AB12 malignant mesothelioma cell inoculation into the pleural cavity. The impact of MMC on tumor growth, animal survival, tumor-infiltrating leucocytes, gut microbiome, and fecal metabolome was evaluated and compared with those of control animals.

Results

The MMC delayed tumor growth and significantly prolonged the survival of immunocompetent animals (P = .0015) but not that of athymic mice. The improved tumor control in immunocompetent mice correlated with increased infiltration of CD3+CD8+GRZB+ cytotoxic T lymphocytes in tumors. Gut microbiota analyses indicated an enrichment in producers of short chain fatty acids in MMC-treated animals. Finally, we observed a positive correlation between the level of fecal short chain fatty acids and abundance of tumor-infiltrating cytotoxic T cells in malignant pleural mesothelioma.

Conclusions

MMC administration boosts antitumor immunity, which correlates with a change in gut microbiome and metabolome. MMC may represent a valuable treatment option to combine with immunotherapy in patients with cancer.

The intersection of host in vivo metabolism and immune responses to infection with kinetoplastid and apicomplexan parasites

SUMMARYProtozoan parasite infection dramatically alters host metabolism, driven by immunological demand and parasite manipulation strategies. Immunometabolic checkpoints are often exploited by kinetoplastid and protozoan parasites to establish chronic infection, which can significantly impair host metabolic homeostasis. The recent growth of tools to analyze metabolism is expanding our understanding of these questions. Here, we review and contrast host metabolic alterations that occur in vivo during infection with Leishmania, trypanosomes, Toxoplasma, Plasmodium, and Cryptosporidium. Although genetically divergent, there are commonalities among these pathogens in terms of metabolic needs, induction of the type I immune responses required for clearance, and the potential for sustained host metabolic dysbiosis. Comparing these pathogens provides an opportunity to explore how transmission strategy, nutritional demand, and host cell and tissue tropism drive similarities and unique aspects in host response and infection outcome and to design new strategies to treat disease.

Genetically predicted causal effects of gut microbiota on spinal pain: a two-sample Mendelian randomization analysis

Background

Observational studies have hinted at a correlation between the gut microbiota and spinal pain (SP). However, the impact of the gut microbiota on SP remains inconclusive.

Methods

In this study, we employed a two-sample Mendelian randomization (MR) analysis to explore the causal relationship between the gut microbiota and SP, encompassing neck pain (NP), thoracic spine pain (TSP), low back pain (LBP), and back pain (BP). The compiled gut microbiota data originated from a genome-wide association study (GWAS) conducted by the MiBioGen consortium (n = 18,340). Summary data for NP were sourced from the UK Biobank, TSP from the FinnGen Biobank, and LBP from both the UK Biobank and FinnGen Biobank. Summary data for BP were obtained from the UK Biobank. The primary analytical approach for assessing causal relationships was the Inverse Variance Weighted (IVW) method, supplemented by various sensitivity analyses to ensure result robustness.

Results

The IVW analysis unveiled 37 bacterial genera with a potential causal relationship to SP. After Benjamini-Hochberg corrected test, four bacterial genera emerged with a strong causal relationship to SP. Specifically, Oxalobacter (OR: 1.143, 95% CI 1.061-1.232, P = 0.0004) and Tyzzerella 3 (OR: 1.145, 95% CI 1.059-1.238, P = 0.0007) were identified as risk factors for LBP, while Ruminococcaceae UCG011 (OR: 0.859, 95% CI 0.791-0.932, P = 0.0003) was marked as a protective factor for LBP, and Olsenella (OR: 0.893, 95% CI 0.839-0.951, P = 0.0004) was recognized as a protective factor for low back pain or/and sciatica. No significant heterogeneity or horizontal pleiotropy was observed through alternative testing methods.

Conclusion

This study establishes a causal relationship between the gut microbiota and SP, shedding light on the "gut-spine" axis. These findings offer novel perspectives for understanding the etiology of SP and provide a theoretical foundation for potential interventions targeting the gut microbiota to prevent and treat SP.

Gut Microbiota: Potential Therapeutic Target for Sickle Cell Disease Pain and Complications

Aim

Sickle cell disease has witnessed a 41.4% surge from 2000 to 2021, significantly affecting morbidity and mortality rates, particularly in children from regions with elevated under-5 mortality rates. Gut microbiota dysbiosis is increasingly recognised in SCD, exacerbating complications, particularly chronic pain, marked by significant alterations of proinflammatory bacteria abundance. This review explores the therapeutic potential of Akkermansia muciniphila and Roseburia spp. in alleviating SCD-related complications, emphasising their roles in maintaining gut barrier integrity, reducing inflammation, and modulating immune responses.

Method

A literature search up to November 2023 using PubMed, MEDLINE, and Google Scholar databases explored SCD pathophysiology, gut microbiota composition, Akkermansia muciniphila and Roseburia spp. abundance, pain and gut dysbiosis in SCD, and butyrate therapy.

Result

A. muciniphila and Roseburia spp. supplementation shows promise in alleviating chronic pain by addressing gut dysbiosis, offering new avenues for sustainable SCD management. This approach holds the potential for reducing reliance on reactive treatments and improving overall quality of life. This research underscores the pivotal role of the gut microbiome in SCD, advocating for personalised treatment approaches.

Conclusion

Further exploration and clinical trials are needed to harness the full potential of these gut bacteria for individuals affected by this challenging condition.

Alterations of circulating free fatty acids in patients with pemphigus vulgaris

Free fatty acids (FFA) have gained research interest owing to their functions in both local and systemic immune regulation. Changes in the serum levels of anti-inflammatory short chain fatty acids (SCFA), primarily derived from the gut microbiota, and pro-inflammatory medium (MCFA) and long (LCFA) chain fatty acids, derived from either the gut microbiota or the diet, have been associated with autoimmunity. Circulating FFA were retrospectively analysed by a gas chromatography-mass spectrometry method in the serum of 18 patients with pemphigus vulgaris (PV) at the baseline and 6 months (n = 10) after immunosuppressive treatments, and 18 healthy controls (HC). Circulating FFA were correlated with the Pemphigus Disease Area Index (PDAI) and serum concentrations of interferon-gamma (IFN-γ), Interleukin (IL)-17A, IL-5, IL-10 and IL-21. Principal Component analysis computed on FFA abundances revealed significant differences in the profile of SCFA (p = 0,012), MCFA (p = 0.00015) and LCFA (p = 0,035) between PV patients and HC, which were not significantly changed by immunosuppressive treatments. PV patients showed a significantly lower serum concentration of propionic (p < 0.0005) and butyric (p < 0.0005) acids, SCFA with anti-inflammatory functions, while hexanoic (p < 0.0005) and hexadecanoic (p = 0.0006) acids, pro-inflammatory MCFA and LCFA respectively, were over-represented. Treatments induced a significant decrease of hexanoic (p = 0.035) and a further increase of hexadecanoic (p = 0.046) acids. Positive correlations emerged between IFN-γ and acetic acid (Rho = 0.60), IFN-γ and hexanoic acid (Rho = 0.46), IL-5 and both hexadecanoic acid (Rho = 0.50) and octadecanoic acid (Rho = 0.53), butyric acid and PDAI (Rho = 0.53). PV was associated with a remarked imbalance of circulating FFA compared to HC. The serum alterations of SCFA, MCFA, and LCFA may contribute to promoting inflammation in PV. Deeper insights into the immunomodulatory functions of these molecules may pave the way for personalized dietary interventions in PV patients.

Cardiovascular risk of dietary trimethylamine oxide precursors and the therapeutic potential of resveratrol and its derivatives

Overall diet, lifestyle choices, genetic predisposition, and other underlying health conditions may contribute to higher trimethylamine N-oxide (TMAO) levels and increased cardiovascular risk. This review explores the potential therapeutic ability of RSV to protect against cardiovascular diseases (CVD) and affect TMAO levels. This review considers recent studies on the association of TMAO with CVD. It also examines the sources, mechanisms, and metabolism of TMAO along with TMAO-induced cardiovascular events. Plant polyphenolic compounds, including resveratrol (RSV), and their cardioprotective mechanism of regulating TMAO levels and modifying gut microbiota are also discussed here. RSV's salient features and bioactive properties in reducing CVD have been evaluated. The close relationship between TMAO and CVD is clearly understood from currently available data, making it a potent biomarker for CVD. Precise investigation, including clinical trials, must be performed to understand RSV's mechanism, dose, effects, and derivatives as a cardioprotectant agent.

Short-chain fatty acids (SCFA) in infants' plasma and corresponding mother's milk and plasma in relation to subsequent sensitisation and atopic disease

BACKGROUND

Short-chain fatty acids (SCFAs) in intestinal contents may influence immune function, while less is known about SCFAs in blood plasma. The aims were to investigate the relation between infants' and maternal plasma SCFAs, as well as SCFAs in mother's milk, and relate SCFA concentrations in infant plasma to subsequent sensitisation and atopic disease.

METHODS

Infant plasma (N = 148) and corresponding mother's milk and plasma were collected four months postpartum. Nine SCFA (formic, acetic, propionic, isobutyric, butyric, succinic, valeric, isovaleric, and caproic acid) were analysed by UPLC-MS. At 12 months of age, atopic disease was diagnosed by a pediatric allergologist, and sensitisation was measured by skin prick test. All families participated in the Swedish birth cohort NICE (Nutritional impact on Immunological maturation during Childhood in relation to the Environment).

FINDINGS

Infants with sensitisation, atopic eczema, or food allergy had significantly lower concentrations of five, three, and two SCFAs, respectively, in plasma at four months. Logistic regressions models showed significant negative associations between formic, succinic, and caproic acid and sensitisation [ORadj (95% CI) per SD: 0.41 (0.19-0.91); 0.19 (0.05-0.75); 0.25 (0.09-0.66)], and between acetic acid and atopic eczema [0.42 (0.18-0.95)], after adjusting for maternal allergy. Infants' and maternal plasma SCFA concentrations correlated strongly, while milk SCFA concentrations were unrelated to both. Butyric and caproic acid concentrations were enriched around 100-fold, and iso-butyric and valeric acid around 3-5-fold in mother's milk, while other SCFAs were less prevalent in milk than in plasma.

INTERPRETATION

Butyric and caproic acid might be actively transported into breast milk to meet the needs of the infant, although mechanistic studies are needed to confirm this. The negative associations between certain SCFAs on sensitisation and atopic disease adds to prior evidence regarding their immunoregulatory potential.

FUNDING

Swedish Research Council (Nr. 2013-3145, 2019-0137 and 2023-02217 to A-S.S.), Swedish Research Council for Health, Working Life and Welfare FORTE, Nr 2018-00485 to A.W.), The Swedish Asthma and Allergy Association's Research Fund (2020-0020 to A.S.).

Application of Microbiome-Based Therapies in Chronic Respiratory Diseases

The application of microbiome-based therapies in various areas of human disease has recently increased. In chronic respiratory disease, microbiome-based clinical applications are considered compelling options due to the limitations of current treatments. The lung microbiome is ecologically dynamic and affected by various conditions, and dysbiosis is associated with disease severity, exacerbation, and phenotype as well as with chronic respiratory disease endotype. However, it is not easy to directly modulate the lung microbiome. Additionally, studies have shown that chronic respiratory diseases can be improved by modulating gut microbiome and administrating metabolites. Although the composition, diversity, and abundance of the microbiome between the gut and lung are considerably different, modulation of the gut microbiome could improve lung dysbiosis. The gut microbiome influences that of the lung via bacterial-derived components and metabolic degradation products, including short-chain fatty acids. This phenomenon might be associated with the cross-talk between the gut microbiome and lung, called gut-lung axis. There are multiple alternatives to modulate the gut microbiome, such as prebiotics, probiotics, and postbiotics ingestion and fecal material transplantation. Several studies have shown that high-fiber diets, for example, present beneficial effects through the production of short-chain fatty acids. Additionally, genetically modified probiotics to secrete some beneficial molecules might also be utilized to treat chronic respiratory diseases. Further studies on microbial modulation to regulate immunity and potentiate conventional pharmacotherapy will improve microbiome modulation techniques, which will develop as a new therapeutic area in chronic respiratory diseases.

Association between gut health and gut microbiota in a polluted environment

Animals host complex bacterial communities in their gastrointestinal tracts, with which they share a mutualistic interaction. The numerous effects these interactions grant to the host include regulation of the immune system, defense against pathogen invasion, digestion of otherwise undigestible foodstuffs, and impacts on host behaviour. Exposure to stressors, such as environmental pollution, parasites, and/or predators, can alter the composition of the gut microbiome, potentially affecting host-microbiome interactions that can be manifest in the host as, for example, metabolic dysfunction or inflammation. However, whether a change in gut microbiota in wild animals associates with a change in host condition is seldom examined. Thus, we quantified whether wild bank voles inhabiting a polluted environment, areas where there are environmental radionuclides, exhibited a change in gut microbiota (using 16S amplicon sequencing) and concomitant change in host health using a combined approach of transcriptomics, histological staining analyses of colon tissue, and quantification of short-chain fatty acids in faeces and blood. Concomitant with a change in gut microbiota in animals inhabiting contaminated areas, we found evidence of poor gut health in the host, such as hypotrophy of goblet cells and likely weakened mucus layer and related changes in Clca1 and Agr2 gene expression, but no visible inflammation in colon tissue. Through this case study we show that inhabiting a polluted environment can have wide reaching effects on the gut health of affected animals, and that gut health and other host health parameters should be examined together with gut microbiota in ecotoxicological studies.

Oral administration of LfcinB alleviates DSS-induced colitis by improving the intestinal barrier and microbiota

Ulcerative colitis (UC) is a kind of inflammatory bowel disease (IBD) that often recurs and is difficult to cure, and no drugs with few side effects are available to treat this disease. LfcinB is a small molecular peptide obtained by the hydrolysis of bovine lactoferrin in the digestive tract of animals. It has strong antibacterial and anti-inflammatory activities. However, direct evidence that LfcinB improves the condition of colitis in mice is rarely reported. In this study, UC was induced in mice by adding 2.5% dextran sulfate (DSS) to drinking water and LfcinB was orally administered. The results showed that oral administration of LfcinB improved colonic tissue damage and inflammatory cell infiltration, increased the expression of tight junction proteins, and down-regulated the phosphorylation of proteins related to the NF-κB/MAPK inflammatory signalling pathway in mice. It also significantly suppressed the relative abundance of potentially pathogenic bacteria (Bacteroides, Barnesiella and Escherichia) in the intestinal flora. In conclusion, oral administration of LfcinB significantly alleviated DSS-induced UC. This may be related to the regulation of inflammatory signalling pathways and gut microbial composition by LfcinB.

Microbiota-gut-brain axis and its therapeutic applications in neurodegenerative diseases

The human gastrointestinal tract is populated with a diverse microbial community. The vast genetic and metabolic potential of the gut microbiome underpins its ubiquity in nearly every aspect of human biology, including health maintenance, development, aging, and disease. The advent of new sequencing technologies and culture-independent methods has allowed researchers to move beyond correlative studies toward mechanistic explorations to shed light on microbiome-host interactions. Evidence has unveiled the bidirectional communication between the gut microbiome and the central nervous system, referred to as the "microbiota-gut-brain axis". The microbiota-gut-brain axis represents an important regulator of glial functions, making it an actionable target to ameliorate the development and progression of neurodegenerative diseases. In this review, we discuss the mechanisms of the microbiota-gut-brain axis in neurodegenerative diseases. As the gut microbiome provides essential cues to microglia, astrocytes, and oligodendrocytes, we examine the communications between gut microbiota and these glial cells during healthy states and neurodegenerative diseases. Subsequently, we discuss the mechanisms of the microbiota-gut-brain axis in neurodegenerative diseases using a metabolite-centric approach, while also examining the role of gut microbiota-related neurotransmitters and gut hormones. Next, we examine the potential of targeting the intestinal barrier, blood-brain barrier, meninges, and peripheral immune system to counteract glial dysfunction in neurodegeneration. Finally, we conclude by assessing the pre-clinical and clinical evidence of probiotics, prebiotics, and fecal microbiota transplantation in neurodegenerative diseases. A thorough comprehension of the microbiota-gut-brain axis will foster the development of effective therapeutic interventions for the management of neurodegenerative diseases.

More than nutrition: Therapeutic potential and mechanism of human milk oligosaccharides against necrotizing enterocolitis

Human milk is the most valuable source of nutrition for infants. The structure and function of human milk oligosaccharides (HMOs), which are key components of human milk, have long been attracting particular research interest. Several recent studies have found HMOs to be efficacious in the prevention and treatment of necrotizing enterocolitis (NEC). Additionally, they could be developed in the future as non-invasive predictive markers for NEC. Based on previous findings and the well-defined functions of HMOs, we summarize potential protective mechanisms of HMOs against neonatal NEC, which include: modulating signal receptor function, promoting intestinal epithelial cell proliferation, reducing apoptosis, restoring intestinal blood perfusion, regulating microbial prosperity, and alleviating intestinal inflammation. HMOs supplementation has been demonstrated to be protective against NEC in both animal studies and clinical observations. This calls for mass production and use of HMOs in infant formula, necessitating more research into the safety of industrially produced HMOs and the appropriate dosage in infant formula.

The role of gut microbiota in intestinal disease: from an oxidative stress perspective

Recent studies have indicated that gut microbiota-mediated oxidative stress is significantly associated with intestinal diseases such as colorectal cancer, ulcerative colitis, and Crohn's disease. The level of reactive oxygen species (ROS) has been reported to increase when the gut microbiota is dysregulated, especially when several gut bacterial metabolites are present. Although healthy gut microbiota plays a vital role in defending against excessive oxidative stress, intestinal disease is significantly influenced by excessive ROS, and this process is controlled by gut microbiota-mediated immunological responses, DNA damage, and intestinal inflammation. In this review, we discuss the relationship between gut microbiota and intestinal disease from an oxidative stress perspective. In addition, we also provide a summary of the most recent therapeutic approaches for preventing or treating intestinal diseases by modifying gut microbiota.

Bacteroidaceae, Bacteroides, and Veillonella: emerging protectors against Graves' disease

Background

Graves' disease (GD) is the most common cause of hyperthyroidism, and its pathogenesis remains incompletely elucidated. Numerous studies have implicated the gut microbiota in the development of thyroid disorders. This study employs Mendelian randomization analysis to investigate the characteristics of gut microbiota in GD patients, aiming to offer novel insights into the etiology and treatment of Graves' disease.

Methods

Two-sample Mendelian randomization (MR) analysis was employed to assess the causal relationship between Graves' disease and the gut microbiota composition. Gut microbiota data were sourced from the international consortium MiBioGen, while Graves' disease data were obtained from FINNGEN. Eligible single nucleotide polymorphisms (SNPs) were selected as instrumental variables. Multiple analysis methods, including inverse variance-weighted (IVW), MR-Egger regression, weighted median, weighted mode, and MR-RAPS, were utilized. Sensitivity analyses were conducted employing MR-Egger intercept test, Cochran's Q test, and leave-one-out analysis as quality control measures.

Results

The Mendelian randomization study conducted in a European population revealed a decreased risk of Graves' disease associated with Bacteroidaceae (Odds ratio (OR) [95% confidence interval (CI)]: 0.89 [0.89 ~ 0.90], adjusted P value: <0.001), Bacteroides (OR: [95% CI]: 0.555 [0.437 ~ 0.706], adjusted P value: <0.001), and Veillonella (OR [95% CI]: 0.632 [0.492 ~ 0.811], adjusted P value: 0.016). No significant evidence of heterogeneity, or horizontal pleiotropy was detected. Furthermore, the preliminary MR analysis identified 13 bacterial species including Eubacterium brachy group and Family XIII AD3011 group, exhibiting significant associations with Graves' disease onset, suggesting potential causal effects.

Conclusion

A causal relationship exists between gut microbiota and Graves' disease. Bacteroidaceae, Bacteroides, and Veillonella emerge as protective factors against Graves' disease development. Prospective probiotic supplementation may offer a novel avenue for adjunctive treatment in the management of Graves' disease in the future.

Potential effects of nutrition-induced alteration of gut microbiota on inflammatory bowel disease: A review

Inflammatory bowel disease (IBD), mainly comprising ulcerative colitis and Crohn's disease, is a group of gradually progressive diseases bringing significant mental anguish and imposes serious economic burdens. Interplay of genetic, environmental, and immunological factors have been implicated in its pathogenesis. Nutrients, as crucial environmental determinants, mainly encompassing carbohydrates, fats, proteins, and micronutrients, are closely related to the pathogenesis and development of IBD. Nutrition is essential for maintaining the dynamic balance of intestinal eco-environments to ensure intestinal barrier and immune homeostasis, while this balance can be disrupted easily by maladjusted nutrition. Research has firmly established that nutrition has the potential to shape the composition and function of gut microbiota to affect the disease course. Unhealthy diet and eating disorders lead to gut microbiota dysbiosis and further destroy the function of intestinal barrier such as the disruption of membrane integrity and increased permeability, thereby triggering intestinal inflammation. Notably, appropriate nutritional interventions, such as the Mediterranean diet, can positively modulate intestinal microecology, which may provide a promising strategy for future IBD prevention. In this review, we provide insights into the interplay between nutrition and gut microbiota and its effects on IBD and present some previously overlooked lines of evidence regarding the role of derived metabolites in IBD processes, such as trimethylamine N-oxide and imidazole propionate. Furthermore, we provide some insights into reducing the risk of onset and exacerbation of IBD by modifying nutrition and discuss several outstanding challenges and opportunities for future study.

Gut microbiota-derived metabolites associate with circulating immune cell subsets in unexplained recurrent spontaneous abortion

Currently, the precise causes of over 40 % of recurrent spontaneous abortion (RSA) cases cannot be identified, leading to the term "unexplained RSA" (URSA). Through an exploration of the gut microbiota, metabolites, and immune cell subsets in URSA, this study establishes a link between gut microbiota-derived metabolites and immune cells. The results indicate reduced diversity in the gut microbiota of URSA. Targeted metabolomic analyses reveal decreased levels of gut microbiota-derived deoxycholic acid (DCA), glycolithocholic acid (GLCA), acetate, propionate, and butyrate in URSA. Furthermore, elevated frequencies of Th1, Th17, and plasma B cells, along with decreased frequencies of Tregs and Bregs, are observed in the peripheral blood of URSA. The results demonstrate correlations between the levels of gut microbiota-derived bile acids and short-chain fatty acids and the frequencies of various immune cell subsets in circulation. Collectively, this study uncovers an association between gut microbiota-derived metabolites and circulating immune cell subsets in URSA.

Possible connection between intestinal tuft cells, ILC2s and obesity

Intestinal tuft cells (TCs) are defined as chemosensory cells that can "taste" danger and induce immune responses. They play a critical role in gastrointestinal parasite invasion, inflammatory bowel diseases and high-fat diet-induced obesity. Intestinal IL-25, the unique product of TCs, is a key activator of type 2 immunity, especially to promote group 2 innate lymphoid cells (ILC2s) to secret IL-13. Then the IL-13 mainly promotes intestinal stem cell (ISCs) proliferation into TCs and goblet cells. This pathway formulates the circuit in the intestine. This paper focuses on the potential role of the intestinal TC, ILC2 and their circuit in obesity-induced intestinal damage, and discussion on further study and the potential therapeutic target in obesity.

Microbiota and glioma: a new perspective from association to clinical translation

Gliomas pose a significant challenge in oncology due to their malignant nature, aggressive growth, frequent recurrence, and complications posed by the blood-brain barrier. Emerging research has revealed the critical role of gut microbiota in influencing health and disease, indicating its possible impact on glioma pathogenesis and treatment responsiveness. This review focused on existing evidence and hypotheses on the relationship between microbiota and glioma from progression to invasion. By discussing possible mechanisms through which microbiota may affect glioma biology, this paper offers new avenues for targeted therapies and precision medicine in oncology.

Vagal interoception of microbial metabolites from the small intestinal lumen

The vagus nerve is proposed to enable communication between the gut microbiome and brain, but activity-based evidence is lacking. Herein, we assess the extent of gut microbial influences on afferent vagal activity and metabolite signaling mechanisms involved. We find that mice reared without microbiota (germ-free, GF) exhibit decreased vagal afferent tone relative to conventionally colonized mice (specific pathogen-free, SPF), which is reversed by colonization with SPF microbiota. Perfusing non-absorbable antibiotics (ABX) into the small intestine of SPF mice, but not GF mice, acutely decreases vagal activity, which is restored upon re-perfusion with bulk lumenal contents or sterile filtrates from the small intestine and cecum of SPF, but not GF, mice. Of several candidates identified by metabolomic profiling, microbiome-dependent short-chain fatty acids, bile acids, and 3-indoxyl sulfate stimulate vagal activity with varied response kinetics, which is blocked by co-perfusion of pharmacological antagonists of FFAR2, TGR5, and TRPA1, respectively, into the small intestine. At the single-unit level, serial perfusion of each metabolite class elicits more singly responsive neurons than dually responsive neurons, suggesting distinct neuronal detection of different microbiome- and macronutrient-dependent metabolites. Finally, microbial metabolite-induced increases in vagal activity correspond with activation of neurons in the nucleus of the solitary tract, which is also blocked by co-administration of their respective receptor antagonists. Results from this study reveal that the gut microbiome regulates select metabolites in the intestinal lumen that differentially activate chemosensory vagal afferent neurons, thereby enabling microbial modulation of interoceptive signals for gut-brain communication.

HIGHLIGHTS

Microbiota colonization status modulates afferent vagal nerve activityGut microbes differentially regulate metabolites in the small intestine and cecumSelect microbial metabolites stimulate vagal afferents with varied response kineticsSelect microbial metabolites activate vagal afferent neurons and brainstem neurons via receptor-dependent signaling.

Gut-Brain Axis Deregulation and Its Possible Contribution to Neurodegenerative Disorders

The gut-brain axis is an essential communication pathway between the central nervous system (CNS) and the gastrointestinal tract. The human microbiota is composed of a diverse and abundant microbial community that compasses more than 100 trillion microorganisms that participate in relevant physiological functions such as host nutrient metabolism, structural integrity, maintenance of the gut mucosal barrier, and immunomodulation. Recent evidence in animal models has been instrumental in demonstrating the possible role of the microbiota in neurodevelopment, neuroinflammation, and behavior. Furthermore, clinical studies suggested that adverse changes in the microbiota can be considered a susceptibility factor for neurological disorders (NDs), such as Alzheimer's disease (AD), Parkinson's disease (PD), Huntington's disease (HD), and amyotrophic lateral sclerosis (ALS). In this review, we will discuss evidence describing the role of gut microbes in health and disease as a relevant risk factor in the pathogenesis of neurodegenerative disorders, including AD, PD, HD, and ALS.

Sutterella and its metabolic pathways positively correlate with vaccine-elicited antibody responses in infant rhesus macaques

Introduction

It is becoming clearer that the microbiota helps drive responses to vaccines; however, little is known about the underlying mechanism. In this study, we aimed to identify microbial features that are associated with vaccine immunogenicity in infant rhesus macaques.

Methods

We analyzed 16S rRNA gene sequencing data of 215 fecal samples collected at multiple timepoints from 64 nursery-reared infant macaques that received various HIV vaccine regimens. PERMANOVA tests were performed to determine factors affecting composition of the gut microbiota throughout the first eight months of life in these monkeys. We used DESeq2 to identify differentially abundant bacterial taxa, PICRUSt2 to impute metagenomic information, and mass spectrophotometry to determine levels of fecal short-chain fatty acids and bile acids.

Results

Composition of the early-life gut microbial communities in nursery-reared rhesus macaques from the same animal care facility was driven by age, birth year, and vaccination status. We identified a Sutterella and a Rodentibacter species that positively correlated with vaccine-elicited antibody responses, with the Sutterella species exhibiting more robust findings. Analysis of Sutterella-related metagenomic data revealed five metabolic pathways that significantly correlated with improved antibody responses following HIV vaccination. Given these pathways have been associated with short-chain fatty acids and bile acids, we quantified the fecal concentration of these metabolites and found several that correlated with higher levels of HIV immunogen-elicited plasma IgG.

Discussion

Our findings highlight an intricate bidirectional relationship between the microbiota and vaccines, where multiple aspects of the vaccination regimen modulate the microbiota and specific microbial features facilitate vaccine responses. An improved understanding of this microbiota-vaccine interplay will help develop more effective vaccines, particularly those that are tailored for early life.

Oregano essential oil modulates colonic homeostasis and intestinal barrier function in fattening bulls

Oregano essential oil (OEO) primarily contains phenolic compounds and can serve as a dietary supplement for fattening bulls. However, the precise molecular mechanism underlying this phenomenon remains largely elusive. Therefore, this study investigated the impact of adding OEO to diet on the integrity of the intestinal barrier, composition of the colonic microbiome, and production of microbial metabolites in fattening bulls. Our goal was to provide insights into the utilization of plant essential oil products in promoting gastrointestinal health and welfare in animals. We employed amplicon sequencing and metabolome sequencing techniques to investigate how dietary supplementation with OEO impacted the intestinal barrier function in bulls. The inclusion of OEO in the diet resulted in several notable effects on the colon of fattening bulls. These effects included an increase in the muscle thickness of the colon, goblet cell number, short-chain fatty acid concentrations, digestive enzyme activity, relative mRNA expression of intestinal barrier-related genes, and relative expression of the anti-inflammatory factor IL-10. Additionally, α-amylase activity and the relative mRNA expression of proinflammatory cytokines decreased. Moreover, dietary OEO supplementation increased the abundance of intestinal Bacteroides, Coprobacillus, Lachnospiraceae_UCG_001, and Faecalitalea. Metabolomic analysis indicated that OEO primarily increased the levels of 5-aminovaleric acid, 3-methoxysalicylic acid, and creatinine. In contrast, the levels of maltose, lactulose, lactose, and D-trehalose decreased. Correlation analysis showed that altered colonic microbes and metabolites affected intestinal barrier function. Taken together, these results demonstrate that OEO facilitates internal intestinal environmental homeostasis by promoting the growth of beneficial bacteria while inhibiting harmful ones.