Gut Microbial Metabolite Butyrate and Its Therapeutic Role in Inflammatory Bowel Disease: A Literature Review

Alleviating Pyroptosis of Intestinal Epithelial Cells to Restore Mucosal Integrity in Ulcerative Colitis by Targeting Delivery of 4-Octyl-Itaconate

Current therapies primarily targeting inflammation often fail to address the root relationship between intestinal mucosal integrity and the resulting dysregulated cell death and ensuing inflammation in ulcerative colitis (UC). First, UC tissues from human and mice models in this article both emphasize the crucial role of Gasdermin E (GSDME)-mediated pyroptosis in intestinal epithelial cells (IECs) as it contributes to colitis by releasing proinflammatory cytokines, thereby compromising the intestinal barrier. Then, 4-octyl-itaconate (4-OI), exhibiting potential for anti-inflammatory activity in inhibiting pyroptosis, was encapsulated by butyrate-modified liposome (4-OI/BLipo) to target delivery for IECs. In brief, 4-OI/BLipo exhibited preferential accumulation in inflamed colonic epithelium, attributed to over 95% of butyrate being produced and absorbed in the colon. As expected, epithelium barriers were restored significantly by alleviating GSDME-mediated pyroptosis in colitis. Accordingly, the permeability of IECs was restored, and the resulting inflammation, mucosal epithelium, and balance of gut flora were reprogrammed, which offers a hopeful approach to the effective management of UC.

Advances and optimization strategies in bacteriophage therapy for treating inflammatory bowel disease

In the advancement of Inflammatory Bowel Disease (IBD) treatment, existing therapeutic methods exhibit limitations; they do not offer a complete cure for IBD and can trigger adverse side effects. Consequently, the exploration of novel therapies and multifaceted treatment strategies provides patients with a broader range of options. Within the framework of IBD, gut microbiota plays a pivotal role in disease onset through diverse mechanisms. Bacteriophages, as natural microbial regulators, demonstrate remarkable specificity by accurately identifying and eliminating specific pathogens, thus holding therapeutic promise. Although clinical trials have affirmed the safety of phage therapy, its efficacy is prone to external influences during storage and transport, which may affect its infectivity and regulatory roles within the microbiota. Improving the stability and precise dosage control of bacteriophages-ensuring robustness in storage and transport, consistent dosing, and targeted delivery to infection sites-is crucial. This review thoroughly explores the latest developments in IBD treatment and its inherent challenges, focusing on the interaction between the microbiota and bacteriophages. It highlights bacteriophages' potential as microbiome modulators in IBD treatment, offering detailed insights into research on bacteriophage encapsulation and targeted delivery mechanisms. Particular attention is paid to the functionality of various carrier systems, especially regarding their protective properties and ability for colon-specific delivery. This review aims to provide a theoretical foundation for using bacteriophages as microbiome modulators in IBD treatment, paving the way for enhanced regulation of the intestinal microbiota.

Resveratrol improves diabetic kidney disease by modulating the gut microbiota-short chain fatty acids axis in db/db mice

Diabetic kidney disease is associated with the dysbiosis of the gut microbiota and its metabolites. db/db mice were fed chow diet with or without 0.4% resveratrol for 12 weeks, after which the gut microbiota, faecal short-chain fatty acids (SCFAs), and renal fibrosis were analysed. Resveratrol ameliorated the progression of diabetic kidney disease and alleviated tubulointerstitial fibrosis. Further studies showed that gut microbiota dysbiosis was modulated by resveratrol, characterised by the expansion of SCFAs-producing bacteria Faecalibaculum and Lactobacillus, which increased the concentrations of SCFAs (especially acetic acid) in the faeces. Moreover, microbiota transplantation experiments found that alteration of the gut microbiota contributed to the prevention of diabetic kidney disease. Acetate treatment ameliorated proteinuria, glomerulosclerosis and tubulointerstitial fibrosis in db/db mice. Overall, resveratrol improved the progression of diabetic kidney disease by suppressing tubulointerstitial fibrosis, which may be involved, at least in part, in the regulation of the gut microbiota-SCFAs axis.

The effect of oral butyrate on colonic short-chain fatty acid transporters and receptors depends on microbial status

Butyrate, a metabolite produced by gut bacteria, has demonstrated beneficial effects in the colon and has been used to treat inflammatory bowel diseases. However, the mechanism by which butyrate operates remains incompletely understood. Given that oral butyrate can exert either a direct impact on the gut mucosa or an indirect influence through its interaction with the gut microbiome, this study aimed to investigate three key aspects: (1) whether oral intake of butyrate modulates the expression of genes encoding short-chain fatty acid (SCFA) transporters (Slc16a1, Slc16a3, Slc16a4, Slc5a8, Abcg2) and receptors (Hcar2, Ffar2, Ffar3, Olfr78, Olfr558) in the colon, (2) the potential involvement of gut microbiota in this modulation, and (3) the impact of oral butyrate on the expression of colonic SCFA transporters and receptors during colonic inflammation. Specific pathogen-free (SPF) and germ-free (GF) mice with or without DSS-induced inflammation were provided with either water or a 0.5% sodium butyrate solution. The findings revealed that butyrate decreased the expression of Slc16a1, Slc5a8, and Hcar2 in SPF but not in GF mice, while it increased the expression of Slc16a3 in GF and the efflux pump Abcg2 in both GF and SPF animals. Moreover, the presence of microbiota was associated with the upregulation of Hcar2, Ffar2, and Ffar3 expression and the downregulation of Slc16a3. Interestingly, the challenge with DSS did not alter the expression of SCFA transporters, regardless of the presence or absence of microbiota, and the effect of butyrate on the transporter expression in SPF mice remained unaffected by DSS. The expression of SCFA receptors was only partially affected by DSS. Our results indicate that (1) consuming a relatively low concentration of butyrate can influence the expression of colonic SCFA transporters and receptors, with their expression being modulated by the gut microbiota, (2) the effect of butyrate does not appear to result from direct substrate-induced regulation but rather reflects an indirect effect associated with the gut microbiome, and (3) acute colon inflammation does not lead to significant changes in the transcriptional regulation of most SCFA transporters and receptors, with the effect of butyrate in the inflamed colon remaining intact.

The Regulatory Effect of Huangshui Polysaccharides on Intestinal Microbiota and Metabolites during In Vitro Fermentation

Huangshui polysaccharides (HSPs) have attracted extensive attention recently for their biological activity and physicochemical property. This research investigated the extraction, structural characterization, and prebiotic activity of three different HSPs (HSP40-0, HSP60-0, and HSP80-0) in vitro to reveal the scientific support for the high-value utilization of Huangshui. HSPs were heteropolysaccharide with diverse structures and surface morphologies. Comprehensive analysis was conducted through 16S rRNA gene sequencing and metabolite profiling techniques, and results showed that HSPs had different potentials to regulate the gut microbiota due to their different structures; for instance, both HSP40-0 and HSP80-0 could notably increase the relative abundance of Bacteroidota, whereas HSP60-0 could increase the relative abundance of Phascolarctobacterium. In addition, HSPs upregulated beneficial differential metabolites, especially short-chain fatty acids (SCFAs). Fermentation products containing these metabolites exhibited anti-inflammatory effects on LPS-treated Caco-2 cells. This study will provide reference for exploring the relationship between the natural polysaccharide structure and the prebiotic activity and widen the application of Huangshui.

Longevity-associated BPIFB4 gene counteracts the inflammatory signaling

BACKGROUND

Increased levels of pro-inflammatory proteins in plasma can be detected in older individuals and associate with the so called chronic low-grade inflammation, which contributes to a faster progression of aged-related cardiovascular (CV) diseases, including frailty, neurodegeneration, gastro-intestinal diseases and disorders reflected by alterations in the composition of gut microbiota. However, successful genetic programme of long-living individuals alters the trajectory of the ageing process, by promoting an efficient immune response that can counterbalance deleterious effects of inflammation and the CV complications. This is the case of BPIFB4 gene in which, homozygosity for a four single-nucleotide polymorphism (SNP) haplotype, the Longevity-Associated Variant (LAV) correlates with prolonged health span and reduced risk of CV complications and inflammation. The relation between LAV-BPIFB4 and inflammation has been proven in different experimental models, here we hypothesized that also human homozygous carriers of LAV-BPIFB4 gene may experience a lower inflammatory burden as detected by plasma proteomics that could explain their favourable CV risk trajectory over time. Moreover, we explored the therapeutic effects of LAV-BPIFB4 in inflammatory disease and monolayer model of intestinal barrier.

RESULTS

We used high-throughput proteomic approach to explore the profiles of circulating proteins from 591 baseline participants selected from the PLIC cohort according to the BPIFB4 genotype to identify the signatures and differences of BPIFB4 genotypes useful for health and disease management. The observational analysis identified a panel of differentially expressed circulating proteins between the homozygous LAV-BPIFB4 carriers and the other alternative BPIFB4 genotypes highlighting in the latter ones a higher grade of immune-inflammatory markers. Moreover, in vitro studies performed on intestinal epithelial organs from inflammatory bowel disease (IBD) patients and monolayer model of intestinal barrier demonstrated the benefit of LAV-BPIFB4 treatment.

CONCLUSIONS

Homozygosity for LAV-BPIFB4 results in the attenuation of inflammation in PLIC cohort and IBD patients providing preliminary evidences for its therapeutic use in inflammatory disorders that need to be further characterized and confirmed by independent studies.

A host-microbial metabolite interaction gut-on-a-chip model of the adult human intestine demonstrates beneficial effects upon inulin treatment of gut microbiome

Background: The gut and its microbiome have a major impact on many aspects of health and are therefore also an attractive target for drug- or food-based therapies. Here, we report on the added value of combining a microbiome screening model, the i-screen, with fresh intestinal tissue explants in a microfluidic gut-on-a-chip model, the Intestinal Explant Barrier Chip (IEBC). Methods: Adult human gut microbiome (fecal pool of 6 healthy donors) was cultured anaerobically in the i-screen platform for 24 h, without and with exposure to 4 mg/mL inulin. The i-screen cell-free culture supernatant was subsequently applied to the luminal side of adult human colon tissue explants (n = 3 donors), fixed in the IEBC, for 24 h and effects were evaluated. Results: The supplementation of the media with inulin promoted the growth of Anaerostipes, Bifidobacterium, Blautia, and Collinsella in the in vitro i-screen, and triggered an elevated production of butyrate by the microbiota. Human colon tissue exposed to inulin-treated i-screen cell-free culture supernatant or control i-screen cell-free culture supernatant with added short-chain fatty acids (SCFAs) showed improved tissue barrier integrity measured by a 28.2%-34.2% reduction in FITC-dextran 4000 (FD4) leakage and 1.3 times lower transport of antipyrine. Furthermore, the release of pro-inflammatory cytokines IL-1β, IL-6, IL-8, and TNF-α was reduced under these circumstances. Gene expression profiles confirmed these findings, but showed more profound effects for inulin-treated supernatant compared to SCFA-supplemented supernatant. Conclusion: The combination of i-screen and IEBC facilitates the study of complex intestinal processes such as host-microbial metabolite interaction and gut health.

Seasonal variations of airborne microbial diversity in waste transfer stations and preventive effect on Streptococcus pneumoniae induced pulmonary inflammation

Environment, location, and season are important factors that influence the microbiological community, yet, little research on airborne microorganisms in waste transfer stations (WTSs). Here, the airborne bacterial and fungal communities at four WTSs during different seasons were analyzed by high-throughput sequencing. The bacteria were isolated by cultural method and screened bacterium alleviate inflammation induced by Streptococcus pneumoniae (Spn) by regulating gut microbiome. The results revealed that collected bioaerosols from the WTSs varied significantly by location and season. Proteobacteria and Pseudomonadota are prevalent in summer and winter, respectively. Ascomycota was predominant in two seasons. Hazard quotients for adults from four WTSs were below one. Three selected potential probiotics were formulated into a microbial preparation with a carrier that effectively prevented inflammation in bacterial and animal experiments. The expression levels of interleukin-1β, interleukin-6, and tumor necrosis factor-α in Pre group (0.11, 0.17, and 0.48-fold) were significantly lower than Spn group (2.75, 1.71, and 5.01-fold). These mechanisms are associated with changes in gut microbiota composition and short-chain fatty acids (SCFAs) levels, such as affecting Lachnospiraceae lachnospira abundance and acetic acid content. This study provides insights into the potential application of probiotics derived from WTSs as an alternative approach to preventing respiratory infections.

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.

Causal relationship between gut microbiota and gastrointestinal diseases: a mendelian randomization study

BACKGROUND

Recent research increasingly highlights a strong correlation between gut microbiota and the risk of gastrointestinal diseases. However, whether this relationship is causal or merely coincidental remains uncertain. To address this, a Mendelian randomization (MR) analysis was undertaken to explore the connections between gut microbiota and prevalent gastrointestinal diseases.

METHODS

Genome-wide association study (GWAS) summary statistics for gut microbiota, encompassing a diverse range of 211 taxa (131 genera, 35 families, 20 orders, 16 classes, and 9 phyla), were sourced from the comprehensive MiBioGen study. Genetic associations with 22 gastrointestinal diseases were gathered from the UK Biobank, FinnGen study, and various extensive GWAS studies. MR analysis was meticulously conducted to assess the causal relationship between genetically predicted gut microbiota and these gastrointestinal diseases. To validate the reliability of our findings, sensitivity analyses and tests for heterogeneity were systematically performed.

RESULTS

The MR analysis yielded significant evidence for 251 causal relationships between genetically predicted gut microbiota and the risk of gastrointestinal diseases. This included 98 associations with upper gastrointestinal diseases, 81 with lower gastrointestinal diseases, 54 with hepatobiliary diseases, and 18 with pancreatic diseases. Notably, these associations were particularly evident in taxa belonging to the genera Ruminococcus and Eubacterium. Further sensitivity analyses reinforced the robustness of these results.

CONCLUSIONS

The findings of this study indicate a potential genetic predisposition linking gut microbiota to gastrointestinal diseases. These insights pave the way for designing future clinical trials focusing on microbiome-related interventions, including the use of microbiome-dependent metabolites, to potentially treat or manage gastrointestinal diseases and their associated risk factors.

Butyrate Protects and Synergizes with Nicotine against Iron- and Manganese-induced Toxicities in Cell Culture

Toxic exposures to heavy metals, such as iron (Fe) and manganese (Mn), can result in long-range neurological diseases and are therefore of significant environmental and medical concerns. We have previously reported that damage to neuroblastoma-derived dopaminergic cells (SH-SY5Y) by both Fe and Mn could be prevented by pre-treatment with nicotine. Moreover, butyrate, a short chain fatty acid (SCFA) provided protection against salsolinol, a selective dopaminergic toxin, in the same cell line. Here, we broadened the investigation to determine whether butyrate might also protect against Fe and/or Mn, and whether, if combined with nicotine, an additive or synergistic effect might be observed. Both butyrate and nicotine concentration-dependently blocked Fe and Mn toxicities. Ineffective concentrations of nicotine and butyrate, when combined, provided full protection against both Fe and Mn. Moreover, the effects of nicotine but not butyrate could be blocked by mecamylamine, a non-selective nicotinic antagonist. On the other hand, the effects of butyrate, but not nicotine, could be blocked by beta-hydroxy butyrate, a fatty acid-3 receptor antagonist. These results not only provide further support for neuroprotective effects of both nicotine and butyrate but also indicate distinct mechanisms of action for each one. Furthermore, potential utility of butyrate and nicotine combination against heavy metal toxicities is suggested.

Houttuynia cordata thunb. alleviates inflammatory bowel disease by modulating intestinal microenvironment: a research review

Inflammatory bowel disease (IBD) is a complex group of chronic intestinal diseases, the cause of which has not yet been clarified, but it is widely believed that the disorder of the intestinal microenvironment and its related functional changes are key factors in the development of the disease. Houttuynia cordata thunb. is a traditional plant with abundant resources and long history of utilization in China, which has attracted widespread attention in recent years due to its potential in the treatment of IBD. However, its development and utilization are limited owing to the aristolochic acid alkaloids contained in it. Therefore, based on the relationship between the intestinal microenvironment and IBD, this article summarizes the potential mechanisms by which the main active ingredients of Houttuynia cordata thunb., such as volatile oils, polysaccharides, and flavonoids, and related traditional Chinese medicine preparations, such as Xiezhuo Jiedu Formula, alleviate IBD by regulating the intestinal microenvironment. At the same time, combined with current reports, the medicinal and edible safety of Houttuynia cordata thunb. is explained for providing ideas for further research and development of Houttuynia chordate thunb. in IBD disease, more treatment options for IBD patients, and more insights into the therapeutic potential of plants with homology of medicine and food in intestinal diseases, and even more diseases.

Butyrate protects and synergizes with nicotine against iron- and manganese-induced toxicities in cell culture: Implications for neurodegenerative diseases

Toxic exposures to heavy metals, such as iron (Fe) and manganese (Mn), can result in long-range neurological diseases and are therefore of significant environmental and medical concerns. We have previously reported that damage to neuroblastoma-derived dopaminergic cells (SH-SY5Y) by both Fe and Mn could be prevented by pre-treatment with nicotine. Moreover, butyrate, a short chain fatty acid (SCFA) provided protection against salsolinol, a selective dopaminergic toxin, in the same cell line. Here, we broadened the investigation to determine whether butyrate might also protect against Fe and/or Mn, and whether, if combined with nicotine, an additive or synergistic effect might be observed. Both butyrate and nicotine concentration-dependently blocked Fe and Mn toxicities. The ineffective concentrations of nicotine and butyrate, when combined, provided full protection against both Fe and Mn. Moreover, the effects of nicotine but not butyrate could be blocked by mecamylamine, a non-selective nicotinic antagonist. On the other hand, the effects of butyrate, but not nicotine, could be blocked by beta-hydroxy butyrate, a fatty acid-3 receptor antagonist. These results not only provide further support for neuroprotective effects of both nicotine and butyrate but indicate distinct mechanisms of action for each one. Furthermore, potential utility of the combination of butyrate and nicotine against heavy metal toxicities is suggested.

The interconnection between obesity and executive function in adolescence: The role of the gut microbiome

In the United States, adolescent obesity is a growing epidemic associated with maladaptive executive functioning. Likewise, data link the microbiome to obesity. Emerging microbiome research has demonstrated an interconnection between the gut microbiome and the brain, indicating a bidirectional communication system within the gut-microbiome-brain axis in the pathophysiology of obesity. This narrative review identifies and summarizes relevant research connecting adolescent obesity as it relates to three core domains of executive functioning and the contribution of the gut microbiome in the relationship between obesity and executive functions in adolescence. The review suggests that (1) the interconnection between obesity, executive function, and the gut microbiome is a bidirectional connection, and (2) the gut microbiome may mediate the neurobiological pathways between obesity and executive function deficits. The findings of this review provide valuable insights into obesity-associated executive function deficits and elucidate the possible mediation role of the gut microbiome.

Circulating short chain fatty acids and fatigue in patients with head and neck cancer: A longitudinal prospective study

Fatigue among patients with head and neck cancer (HNC) has been associated with higher inflammation. Short-chain fatty acids (SCFAs) have been shown to have anti-inflammatory and immunoregulatory effects. Therefore, this study aimed to examine the association between SCFAs and fatigue among patients with HNC undergoing treatment with radiotherapy with or without concurrent chemotherapy. Plasma SCFAs and the Multidimensional Fatigue Inventory-20 were collected prior to and one month after the completion of treatment in 59 HNC patients. The genome-wide gene expression profile was obtained from blood leukocytes prior to treatment. Lower butyrate concentrations were significantly associated with higher fatigue (p = 0.013) independent of time of assessment, controlling for covariates. A similar relationship was observed for iso/valerate (p = 0.025). Comparison of gene expression in individuals with the top and bottom 33% of butyrate or iso/valerate concentrations prior to radiotherapy revealed 1,088 and 881 significantly differentially expressed genes, respectively (raw p < 0.05). The top 10 Gene Ontology terms from the enrichment analyses revealed the involvement of pathways related to cytokines and lipid and fatty acid biosynthesis. These findings suggest that SCFAs may regulate inflammatory and immunometabolic responses and, thereby, reduce inflammatory-related symptoms, such as fatigue.

Imbalance of gut microbiota is involved in the development of chronic obstructive pulmonary disease: A review

Chronic obstructive pulmonary disease (COPD) is a common chronic disease characterized by chronic airway inflammation and remodeling, which seriously endangers human health. Recent developments in genomics and metabolomics have revealed the roles of the gut microbiota and its metabolites in COPD. Dysbiosis of the gut microbiota directly increases gut permeability, thereby promoting the translocation of pathological bacteria. The gut microbiota and associated metabolites may influence the development and progression of COPD by modulating immunity and inflammation. Furthermore, the systemic hypoxia and oxidative stress that occur in COPD may also be involved in intestinal dysfunction. The cross-talk between the gut and lungs is known as the gut-lung axis; however, an overview of its mechanism is lacking. This review highlights the critical and complex interplay of gut microbiota and immune responses in the gut-lung axis, further explores possible links between the gut and lungs, and summarizes new interventions through diet, probiotics, vitamins, and fecal microbiota transplantation, which are critical to COPD.