Short-chain Fatty Acids Propionate Research Articles

Korean Red Ginseng Polysaccharides Enhance Intestinal IgA Production and Barrier Function via Peyer's Patch Activation in Mice.

Background: Natural products are gaining attention for their potential benefits in gastrointestinal health. Plant-derived polysaccharides are essential for boosting intestinal immunity and maintaining gut homeostasis. This study investigated the effects of Korean red ginseng polysaccharides (KRG-P) on intestinal homeostasis including IgA and SCFA production and mucosal barrier integrity. Methods: Mice were orally administered KRG-P at doses of 50 mg/kg or 200 mg/kg for 10 days. Fecal IgA levels were measured on days 3, 5, and 11 and IgA from cultured Peyer's patch cells from KRG-P-treated mice were analyzed. Additionally, mRNA and protein expression levels of α-defensin, lysozyme, and E-cadherin in the small intestine were examined. Short-chain fatty acids (SCFAs) content in the cecum was also assessed. Results: KRG-P-treated groups showed a significant increase in fecal IgA levels on days 5 and 11, with no notable change on day 3. Cultured Peyer's patch cells from mice demonstrated heightened IgA production. Additionally, KRG-P administration upregulated α-defensin and lysozyme mRNA expression, along with elevated protein expression of E-cadherin, α-defensin, and lysozyme, in the small intestine. KRG-P treatment also led to increased cecal SCFA levels, including acetate, butyrate, and propionate. Conclusions: KRG-P may promote intestinal homeostasis and host defense mechanisms by activating immune cells in Peyer's patches, stimulating IgA production, enhancing antimicrobial peptide expression, and modulating gut microbiota metabolism through increased SCFA production.

Increase in colonic PRopionate as a method of prEVENTing weight gain over 12 months in adults aged 20–40 years (iPREVENT): a multi-centre, double-blind, randomised, parallel-group trial

Obesity drives metabolic disease development. Preventing weight gain during early adulthood could mitigate later-life chronic disease risk. Increased dietary fibre intake, leading to enhanced colonic microbial fermentation and short-chain fatty acid (SCFA) production, is associated with lower body weight. Despite national food policy recommendations to consume 30g of dietary fibre daily, only 9% of adults achieve this target. Inulin-propionate ester (IPE) selectively increases the production of the SCFA propionate in the colon. In previous studies, IPE has prevented weight gain in middle-aged adults over 6 months, compared with the inulin control. IPE is a novel food ingredient that can be added to various commonly consumed foods with a potential health benefit. This 12-month study aimed to determine whether using IPE to increase colonic propionate prevents further weight gain in overweight younger adults. This multi-centre randomised-controlled, double-blind trial was conducted in London and Glasgow, UK. Recruited participants were individuals at risk of weight gain, aged between 20 and 40 years and had an overweight body mass index. Sealed Envelope Software was used to randomise participants to consume 10g of IPE or inulin (control), once per day for 12 months. The primary outcome was the weight gained from baseline to 12 months, analysed by an 'Intention to Treat' strategy. The safety profile and tolerability of IPE were monitored through adverse events and compliance. This study is registered with the International Standard Randomised Controlled Trials (ISRCT) Database (ISRCT number: 16299902). Participants (n=135 per study arm) were recruited from July 2019 to October 2021. At 12 months, there was no significant difference in baseline-adjusted mean weight gain for IPE compared with control (1.02kg, 95% CI:-0.37 to 2.41; p=0.15; n=226). Neither the IPE (+1.22kg) nor the control arm (+0.07kg) unadjusted mean gains in body weight reached the expected 2kg threshold. In the IPE arm, fat-free mass was greater by 1.07kg (95% CI: 0.21-1.93), and blood glucose elevated by 0.11mmol/L (95% CI: 0.01-0.21). Compliance, determined by intake of ≥50% sachets, was reached by 63% of IPE participants. There were no unexpected adverse events or safety concerns. Our study indicates that at 12 months, IPE did not differentially affect weight gain, compared with the inulin control, in adults between 20 and 40 years of age, at risk of obesity. NIHR EME Programme (15/185/16).

P016 METAPROTEOMICS ANALYSIS IN HEALTHY INDIVIDUALS REVEALS A HIGH CARDIOVASCULAR RISK PROFILE ACROSS BLOOD PRESSURE, DIET, HUMAN AND MICROBIAL PROTEINS

Background/Objective: The gut microbiota is a crucial link between diet and cardiovascular health by producing beneficial metabolites, such as short-chain fatty acids (SCFAs), through fibre fermentation. However, most studies have focused on microbial DNA to infer microbiota function. Here, we employed metaproteomics, a novel method to capture gut human and microbiota protein expression profiles concurrently. We aimed to investigate the crosstalk between gut microbiota, diet, host gut health, and blood pressure (BP). Methods: Mass spectrometry-based metaproteomic analysis was performed on 61 faecal samples with paired ambulatory BP monitoring, food intake (food frequency questionnaire), and demographic data. Results: We identified 21,594 microbial and 1,072 human proteins. Traditional risk factors (age, BMI, sex, BP) explained only ∼10% of the proteome variance. However, unsupervised clustering analysis of both human and microbial proteome revealed two distinct clusters (low-risk and high-risk) with significantly different 24-hour systolic BP (mean±SD, low-risk 116±13mmHg vs high-risk: 126±15mmHg, P=0.016), women prevalence (72.4% vs 40.6%, P=0.025), and diet quality (assessed as Athlete Diet Index, 61.6±6.7 vs 57.8±7.6, P=0.044). In the human proteome, the low-risk group had lower expression of the VEGFA-VEGFR2 signalling pathway and tight junction proteins and higher SCFA production (particularly propionate), suggesting an anti-inflammatory gut environment. In the microbial proteome, the low-risk group had higher activity of inorganic ion transport and metabolism-related proteins, with increased expression of acetate kinase that produces both the SCFAs acetate and propionate, particularly in primary fibre-fermenting bacteria, including Phocaeicola dorei and Blautia wexlerae. Finally, via co-expression networks, we identified profilin-1 (PFN1), which contributes to hypertension and atherosclerosis, as a crucial human protein associated with several bacteria present in the high-risk group. Conclusions: Employing an unsupervised clustering based on human and microbial proteomics, we identified two groups of participants with varying traditional and emerging cardiovascular risk factors. This was explained by complex interactions among diet, gut microbiota, and BP. This underscores the need for sophisticated models to understand multifactorial risk factors for cardiovascular disease.

Commensal-derived short-chain fatty acids disrupt lipid membrane homeostasis in Staphylococcus aureus.

The role of commensal anaerobic bacteria in chronic respiratory infections is unclear, yet they can exist in abundances comparable to canonical pathogens in vivo. Their contributions to the metabolic landscape of the host environment may influence pathogen behavior by competing for nutrients and creating inhospitable conditions via toxic metabolites. Here, we reveal a mechanism by which the anaerobe-derived short chain fatty acids (SCFAs) propionate and butyrate negatively affect Staphylococcus aureus physiology by disrupting branched chain fatty acid (BCFA) metabolism. In turn, BCFA impairment results in impaired growth, diminished expression of the agr quorum sensing system, as well as increased sensitivity to membrane-targeting antimicrobials. Altered BCFA metabolism also reduces S. aureus fitness in competition with Pseudomonas aeruginosa, suggesting that airway microbiome composition and the metabolites they produce and exchange directly impact pathogen succession over time. The pleiotropic effects of these SCFAs on S. aureus fitness and their ubiquity as metabolites in animals also suggests that they may be effective as sensitizers to traditional antimicrobial agents when used in combination.

Modulation of the Serum Metabolome by the Short-Chain Fatty Acid Propionate: Potential Implications for Its Cholesterol-Lowering Effect.

(1) Background: Dyslipidemia represents a major risk factor for atherosclerosis-driven cardiovascular disease. Emerging evidence suggests a close relationship between cholesterol metabolism and gut microbiota. Recently, we demonstrated that the short-chain fatty acid (SCFA) propionate (PA) reduces serum cholesterol levels through an immunomodulatory mechanism. Here, we investigated the effects of oral PA supplementation on the human serum metabolome and analyzed changes in the serum metabolome in relation to the cholesterol-lowering properties of PA. (2) Methods: The serum metabolome of patients supplemented with either placebo or propionate orally for 8 weeks was assessed using a combination of flow injection analysis-tandem (FIA-MS/MS) as well as liquid chromatography (LC-MS/MS) and mass spectrometry using a targeted metabolomics kit (MxP®Quant 500 kit: BIOCRATES Life Sciences AG, Innsbruck, Austria). A total of 431 metabolites were employed for further investigation in this study. (3) Results: We observed a significant increase in distinct bile acids (GCDCA: fold change = 1.41, DCA: fold change = 1.39, GUDCA: fold change = 1.51) following PA supplementation over the study period, with the secondary bile acid DCA displaying a significant negative correlation with the serum cholesterol levels. (4) Conclusions: Oral supplementation with PA modulates the serum metabolome with a particular impact on the circulatory bile acid profile. Since cholesterol and bile acid metabolism are interconnected, the elevation of the secondary bile acid DCA may contribute to the cholesterol-lowering effect of PA.

Gut microbiome and cardiometabolic comorbidities in people living with HIV

BackgroundDespite modern antiretroviral therapy (ART), people living with HIV (PLWH) have increased relative risk of inflammatory-driven comorbidities, including cardiovascular disease (CVD). The gut microbiome could be one of several driving factors, along with traditional risk factors and HIV-related risk factors such as coinfections, ART toxicity, and past immunodeficiency.ResultsPLWH have an altered gut microbiome, even after adjustment for known confounding factors including sexual preference. The HIV-related microbiome has been associated with cardiometabolic comorbidities, and shares features with CVD-related microbiota profiles, in particular reduced capacity for short-chain fatty acid (SCFA) generation. Substantial inter-individual variation has so far been an obstacle for applying microbiota profiles for risk stratification. This review covers updated knowledge and recent advances in our understanding of the gut microbiome and comorbidities in PLWH, with specific focus on cardiometabolic comorbidities and inflammation. It covers a comprehensive overview of HIV-related and comorbidity-related dysbiosis, microbial translocation, and microbiota-derived metabolites. It also contains recent data from studies in PLWH on circulating metabolites related to comorbidities and underlying gut microbiota alterations, including circulating levels of the SCFA propionate, the histidine-analogue imidazole propionate, and the protective metabolite indole-3-propionic acid.ConclusionsDespite recent advances, the gut microbiome and related metabolites are not yet established as biomarkers or therapeutic targets. The review gives directions for future research needed to advance the field into clinical practice, including promises and pitfalls for precision medicine.E43Wq5ZcF7qWyj5HQEGoJiVideo

Phytate metabolism is mediated by microbial cross-feeding in the gut microbiota.

Dietary intake of phytate has various reported health benefits. Previous work showed that the gut microbiota can convert phytate to short-chain fatty acids (SCFAs), but the microbial species and metabolic pathway are unclear. Here we identified Mitsuokella jalaludinii as an efficient phytate degrader, which works synergistically with Anaerostipes rhamnosivorans to produce the SCFA propionate. Analysis of published human gut taxonomic profiles revealed that Mitsuokella spp., in particular M. jalaludinii, are prevalent in human gut microbiomes. NMR spectroscopy using 13C-isotope labelling, metabolomic and transcriptomic analyses identified a complete phytate degradation pathway in M. jalaludinii, including production of the intermediate Ins(2)P/myo-inositol. The major end product, 3-hydroxypropionate, was converted into propionate via a synergistic interaction with Anaerostipes rhamnosivorans both in vitro and in mice. Upon [13C6]phytate administration, various 13C-labelled components were detected in mouse caecum in contrast with the absence of [13C6] InsPs or [13C6]myo-inositol in plasma. Caco-2 cells incubated with co-culture supernatants exhibited improved intestinal barrier integrity. These results suggest that the microbiome plays a major role in the metabolism of this phytochemical and that its fermentation to propionate by M. jalaludinii and A. rhamnosivorans may contribute to phytate-driven health benefits.

Butyrate inhibits the malignant biological behaviors of breast cancer cells by facilitating cuproptosis-associated gene expression

BackgroundButyrate is a common short-chain fatty acids (SCFA), and it has been demonstrated to regulate the development of breast cancer (BC), while the underlying mechanism is still unreported.MethodsGas chromatography was used to measure the amounts of SCFA (acetate, propionate, and butyrate) in the feces. Cell viability was measured by the CCK-8 assay. The wound healing assay demonstrated cell migration, and the transwell assay demonstrated cell invasion. The levels of protein and gene were determined by western blot assay and RT-qPCR assay, respectively.ResultsThe levels of SCFA were lower in the faecal samples from BC patients compared to control samples. In cellular experiments, butyrate significantly suppressed the cell viability, migration and invasion of T47D in a dose-dependent manner. In animal experiments, butyrate effectively impeded the growth of BC tumors. Toll like receptor 4 (TLR4) was highly expressed in the tumors from BC patients. Butyrate inhibited the expression of TLR4. In addition, butyrate promoted the expression of cuproptosis-related genes including PDXK (pyridoxal kinase) and SLC25A28 (solute carrier family 25 member 28), which was lowly expressed in BC tumors. Importantly, overexpression of TLR4 can reverses the promotion of butyrate to PDXK and SLC25A28 expression and the prevention of butyrate to the malignant biological behaviors of T47D cells.ConclusionIn summary, butyrate inhibits the development of BC by facilitating the expression of PDXK and SLC25A28 through inhibition of TLR4. Our investigation first identified a connection among butyrate, TLR4 and cuproptosis-related genes in BC progression. These findings may provide novel target for the treatment of BC.

The gut microbial characteristics and underlying mechanisms of patients with different clinical prognoses from immunotherapy by landmark analysis.

2606 Background: A subset of cancer patients could benefit long-termly from immune checkpoints inhibitors (ICIs), which was called smearing effect. Gut microbiota was widely found to be associated with the initial ICIs efficacy and immune-related adverse event (irAE). This study aimed to identify the baseline gut microbiota characteristics of long-benefit patients and explore the possible underlying mechanisms. Methods: Lung cancer patients initially treated with anti-PD-1/PD-L1 therapy were consecutively enrolled from May 2020 to September 2022. All patients were classified into Benefit group, Resistance group and Severe irAE group based on the long-term prognosis. The baseline gut microbiota characteristics were identified by metagenome sequencing. MelonnPan was used to predict the abundances of 79 metabolites. The sequences of autoantigen, lung cancer antigen and anticancer peptides (ACPs) from IEDB and CancerPPD databases were aligned against the scaftigs of fecal samples. Results: 54 patients were enrolled with 24 in Benefit group, 13 in Severe irAE group and 17 in Resistance group. The microorganism composition was significantly different between Benefit group and Resistance group ( P=0.03), while no difference between Benefit group and Severe irAE group ( P=0.93). The co-occurrence network showed the Benefit group patients had the most compact microbiota network. Metabolites prediction analyses showed the short chain fatty acids propionate ( P=0.005) and butyrate/isobutyrate ( P=0.03) were significantly enriched in Benefit group than Resistance group, wherein the acetyl-CoA pathway ( P=0.04) accounted for the largest proportion of butyrate-production ability difference. The beneficial species had more positive correlations with butyrate-producing enzymes ( P<0.001). The microbiota of irAE patients had abundant aligned sequences with antigen epitopes of multiple autoimmune diseases. The total counts of systemic lupus erythematosus-related epitopes were significantly more enriched in patients with immune-related colitis ( P=0.04), especially FDNGRRGRPVTGP ( P=0.02) and IDNGRRGRPITGP ( P=0.02). Likewise, the microbiota of patients with good ICIs efficacy tended to have more abundant cancer-related antigen counts ( P=0.07) and ACPs counts ( P=0.06). Strain-level analysis revealed Escherichia coli and Faecalibacterium prausnitziishowed a centralized trend of genomic variations based on different clinical phenotypes. Conclusions: Long-term benefit patients had converging characteristics of gut microbiota, which coevoluted a compact microbial community with high butyrate-producing ability. The microbiota molecular mimicry of autoimmune and tumor antigen might contribute to irAE and ICIs efficacy. The strain-level genomic variations of specific species may also play a role in clinical phenotypes.

#885 Combination of medium cut-off dialyzer membrane and diet modification to reduce serum concentrations of p-cresyl sulfate and indoxyl sulfate

Abstract Background and Aims Online hemodiafiltration (ol-HDF) may be considered currently as the best choice for chronic hemodialysis (HD) treatment, but medium cut-off (MCO) membranes may provide similar efficiency for larger and protein-bound toxin removal. P-cresyl sulfate (PCS) and indoxyl-sulfate (IS) concentration depends mainly on residual renal function and diet. Increased dietary fiber intake and short-chain fatty acid (SCFA) supplementation were associated with decreased production of PCS and IS. The aim of this study was to pragmatically combine MCO use with diet modification in an attempt to reduce serum concentration of PCS and IS and compare this strategy to online HDF use. Method We report preliminary results from a subset of a study sample with 42 chronic prevalent HD patients in a prospective randomized controlled interventional study. Two weeks after standard bicarbonate HD (BHD), patients were randomized to hemodialysis with MCO membrane (EXP group) or ol-HDF with a standard "high-flux" (HF) dialyzer membrane (CON group). After 4 weeks, both groups were supplemented by a change in the diet with increase of the daily intake of dietary fiber to 30g and addition of a SCFA propionate in the dose of 1g daily for 8 weeks. Two main outcomes were serum concentrations of PCS and IS. Measurements were taken at baseline (after 2 week wash-in period), after 4 weeks of the first intervention phase (MCO vs. ol-HDF; T1), after 8 weeks of the second intervention phase (fiber and SCFA supplementation; T2) and finally, after 4 weeks of wash-out period with BHD (T3). Results From 42 participants, 38 completed the study (63.2% men, 66.4±10.9 years, Charlson comorbidity index 5.7±2.3). In the CON group, serum concentrations of PCS (in μg/ml) were 36.8±19.6 (baseline), 36.9±20.8 (T1), 32.4±17.4 (T2) and 38.6±22.1 (T3). Serum concentrations of IS (in μg/ml) were 31.8±13.0 (baseline), 32.9±14.7 (T1), 29.5±9.1 (T2) and 35.5±16.8 (T3). In the EXP group, serum concentrations of PCS were 33.5± 16.6 (baseline), 35.9±17.8 (T1), 34.0±16.1 (T2) and 37.4±21.5 (T3). Serum concentrations for IS were 39.6±12.6 (baseline), 37.3±12.9 (T1), 42.3±13.5 (T2) and 41.0±12.8 (T3). Repeated measures ANOVA revealed no significant time*group interaction for PCS (F(1,33)=0.479, p=0.698, ŋ2=0.014) and IS (F(1,33)=2.392, p=0.073, ŋ2=0.068). There was a significant within-group increase in serum IS concentration between T2 and T3 in CON group (p=0.042). There was a trend towards a decrease in PCS concentration between T1 and T2 and increase between T2 and T3 in CON group. Conclusion The results of the study suggest both hemodialysis methods are equivalent in eliminating PCS and IS. Additional fiber and SCFA propionate supplementation did not decrease serum PCS and IS concentrations significantly, although there was a trend towards lower serums concentration of PCS after diet modification in CON group.

The gut commensal Blautia maintains colonic mucus function under low-fiber consumption through secretion of short-chain fatty acids

Beneficial gut bacteria are indispensable for developing colonic mucus and fully establishing its protective function against intestinal microorganisms. Low-fiber diet consumption alters the gut bacterial configuration and disturbs this microbe-mucus interaction, but the specific bacteria and microbial metabolites responsible for maintaining mucus function remain poorly understood. By using human-to-mouse microbiota transplantation and ex vivo analysis of colonic mucus function, we here show as a proof-of-concept that individuals who increase their daily dietary fiber intake can improve the capacity of their gut microbiota to prevent diet-mediated mucus defects. Mucus growth, a critical feature of intact colonic mucus, correlated with the abundance of the gut commensal Blautia, and supplementation of Blautia coccoides to mice confirmed its mucus-stimulating capacity. Mechanistically, B. coccoides stimulated mucus growth through the production of the short-chain fatty acids propionate and acetate via activation of the short-chain fatty acid receptor Ffar2, which could serve as a new target to restore mucus growth during mucus-associated lifestyle diseases.

Disordered GPR43/NLRP3 expression in peripheral leukocytes of patients with atrial fibrillation is associated with intestinal short chain fatty acids levels

BackgroundAtrial fibrillation (AF) is associated with circulating inflammation. Short-chain fatty acids (SCFAs) derived from gut microbiota (GM) regulate leukocyte function and inhibit the release of inflammatory cytokines, which are partly mediated by the G-protein-coupled receptor 43 (GPR43) signaling. This study aimed to investigate the expression of GPR43/NOD-like receptors family pyrin domain containing 3 (NLRP3) in leukocytes and the interaction with intestinal SCFAs levels in AF patients.MethodsExpressions of GPR43 and NLRP3 mRNA in peripheral blood leukocytes from 23 AF patients and 25 non-AF controls were detected by quantitative reverse transcription-polymerase chain reaction (qRT-PCR). Expressions of leukocyte GPR43 and NLRP3 protein were evaluated by western blot analysis. The levels of plasma IL-1β were measured by enzyme-linked immunosorbent assay (ELISA). The fecal SCFAs levels based on GC/MS metabolome of corresponding 21 controls and 14 AF patients were acquired from our published dataset. To evaluate the expression of NLRP3 and GPR43 and the release of IL-1β, human THP-1 cells were stimulated with or without SCFAs (acetate, propionate, and butyrate), lipopolysaccharide (LPS), and nigericin in vitro, respectively.ResultsCompared to the controls, the mRNA expression in peripheral leukocytes was significantly reduced in AF patients (P = 0.011) coupled with the increase in downstream leukocyte NLRP3 mRNA expression (P = 0.007) and plasma IL-1β levels (P < 0.001), consistent with changes in GPR43 and NLRP3 protein expression. Furthermore, leukocyte GPR43 mRNA levels were positively correlated with fecal GM-derived acetic acid (P = 0.046) and negatively correlated with NLRP3 mRNA expression (P = 0.024). In contrast to the negative correlation between left atrial diameter (LAD) and GPR43 (P = 0.008), LAD was positively correlated with the leukocyte NLRP3 mRNA levels (P = 0.024). Subsequent mediation analysis showed that 68.88% of the total effect of intestinal acetic acid on AF might be mediated by leukocyte GPR43/NLRP3. The constructed GPR43–NLRP3 score might have a predictive potential for AF detection (AUC = 0.81, P < 0.001). Moreover, SCFAs treatment increased GPR43 expression and remarkably reduced LPS/nigericin-induced NLRP3 expression and IL-1β release in human THP-1 cells in vitro.ConclusionsDisrupted interactions between GPR43 and NLRP3 expression in peripheral blood leukocytes, associated with reduced intestinal GM-derived SCFAs, especially acetic acid, may be involved in AF development and left atrial enlargement by enhancing circulating inflammation.

Alleviative effects of the parthenolide derivative ACT001 on insulin resistance induced by sodium propionate combined with a high-fat diet and its potential mechanisms

The increasing side effects of traditional medications used to treat type II diabetes have made research into the development of safer and more effective natural medications necessary. ACT001, a derivative of parthenolide, has been shown to have good anti-inflammatory and antitumor effects; however, its role in diabetes is unclear. The short-chain fatty acid propionate is a common food preservative that has been found to cause disturbances in glucose metabolism in mice and humans. This study aimed to investigate whether sodium propionate could aggravate insulin resistance in obese mice and cause diabetes and to study the alleviative effects and potential mechanisms of action of ACT001 on insulin resistance in diabetic mice. Type II diabetic mice were adminietered sodium propionate combined with a high-fat diet (HFD + propionate) by gavage daily for four weeks. Biochemical analysis showed that ACT001 significantly affected blood glucose concentration in diabetic mice, mainly by downregulating the expression of phosphoenolpyruvate carboxykinase 2 and glucose-6-phosphatase. Meanwhile, the level of fatty acid-binding protein 4 in the liver was significantly decreased. ACT001 has a protective effect on the liver and adipose tissue of mice. In addition, the results of the running wheel experiment indicated that ACT001 alleviated the circadian rhythm disorder caused by insulin resistance to a certain extent. This study revealed the potential mechanism by which ACT001 alleviates insulin resistance and provides ideas for developing natural antidiabetic drugs.

Poly(D,l-lactide-co-glycolide) particles are metabolised by the gut microbiome and elevate short chain fatty acids

The production of short chain fatty acids (SCFAs) by the colonic microbiome has numerous benefits for human health, including maintenance of epithelial barrier function, suppression of colitis, and protection against carcinogenesis. Despite the therapeutic potential, there is currently no optimal approach for elevating the colonic microbiome's synthesis of SCFAs. In this study, poly(D,l-lactide-co-glycolide) (PLGA) was investigated for this application, as it was hypothesised that the colonic microbiota would metabolise PLGA to its lactate monomers, which would promote the resident microbiota's synthesis of SCFAs. Two grades of spray dried PLGA, alongside a lactate bolus control, were screened in an advanced model of the human colon, known as the M-SHIME® system. Whilst the high molecular weight (Mw) grade of PLGA was stable in the presence of the microbiota sourced from three healthy humans, the low Mw PLGA (PLGA 2) was found to be metabolised. This microbial degradation led to sustained release of lactate over 48 h and increased concentrations of the SCFAs propionate and butyrate. Further, microbial synthesis of harmful ammonium was significantly reduced compared to untreated controls. Interestingly, both types of PLGA were found to influence the composition of the luminal and mucosal microbiota in a donor-specific manner. An in vitro model of an inflamed colonic epithelium also showed the polymer to affect the expression of pro- and anti-inflammatory markers, such as interleukins 8 and 10. The findings of this study reveal PLGA's sensitivity to enzymatic metabolism in the gut, which could be harnessed for therapeutic elevation of colonic SCFAs.

Abstract 2976: The potential use of butyrate and propionate to inhibit oncogenic phenotypes in oral squamous cell carcinoma and triple negative breast cancer

Abstract Background Oral squamous cell carcinoma (OSCC) and triple-negative breast cancer (TNBC) are aggressive cancers with low survival rates, particularly in Hispanics. Since the underpinning mechanisms of oncogenesis for both OSCC and TNBC are multifactorial, the development of novel targeted therapies is limited. The tumor microbiome has been shown to modulate the microenvironment. The microbial product short-chain fatty acids (SCFA) may represent a putative target for treatment as they can potentially inhibit cell growth, proliferation, migration, and induce morphologic changes in cancer cells. We evaluated the impact of the SCFAs butyrate, acetate, and propionate on the oncogenic phenotypes of OECM-1 and MDA-231 cell line models for OSCC and TNBC respectively. Methods OECM-1 and MDA-231 cell lines were cultured in RPMI-1640 medium supplemented with 10% FBS. Cytotoxicity was determined using an alamarBlue assay by treating the cells with SCFA in a series of 7 concentrations starting at 125 mM (1:2 dilution factor) for 24, 48, and 72 hours (h). Proliferation quantification was performed using trypan blue dye after treatment with SCFA for 24h, 48h and 72h. Migration and invasion were measured after treatment for 24h with SCFAs. Comparative analysis of our results was performed using GraphPad Prism v10. Results Higher concentrations of all SCFA decreased cell viability in OSCC and TNBC at all time points. In OECM-1 cells, the average inhibitory concentration of 50% (IC50) was 3mM for butyrate, 382mM for acetate, and 64mM for propionate while in MDA-MB-231 cells, the average IC50 was 4.3mM for butyrate, 462mM for acetate, and 20mM for propionate. Both OECM-1 and MDA-MB-231 cells treated with butyrate and propionate at 5mM resulted in a slower migration after 24h of treatment. Additionally, there was a significant reduction of cell number and proliferation rate after 48h and 72h of butyrate treatment at the concentrations 1mM (p=0.0425) and 5mM (p=0.0007) in OSCC. Conclusions Our results show that butyrate and propionate can reduce oncogenic phenotypes in OSCC and TNBC and may represent a potential target for the development of alternative treatment strategies for both cancers. Future work includes measuring the impact of these SCFA in epithelial-mesenchymal transition, loss of adhesion, and cell death. Citation Format: Angel J. Amaral Maisonet. The potential use of butyrate and propionate to inhibit oncogenic phenotypes in oral squamous cell carcinoma and triple negative breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2976.

Abstract 2441: Higher levels of LPS in blood plasma as potential novel biomarker for cancer risk in Puerto Rican people living with HIV

Abstract Background: People living with HIV (PWH) have a significantly higher risk of developing cancers than people without HIV (PWOH), even with suppressive antiretroviral therapy. Puerto Rico (PR) is considered a high-risk group disproportionately affected by HIV and a priority group for cancer prevention strategies. Dysbiosis of the human microbiota can contribute to persistent inflammation by upregulating TGF-β (microbial-induced oncogenesis biomarker), which can promote the translocation of microbial products into the bloodstream, increasing cancer risk at local and distant sites. However, the relationship between TGF-β, and microbial products such as lipopolysaccharide (LPS) and short-chain fatty acids (SCFA) in relation to HIV infection is poorly understood, therefore we aimed to quantify the levels of LPS and SCFA in the blood plasma of PWH vs. PWOH and investigated their relationship with cancer risk measured by TGF-β. Methods: Blood samples, sociodemographic, and clinical data from 80 adults (50 PWH and 30 PWOH) were collected. PWH were virally suppressed (&amp;lt;50 copies/mL) with a median CD4 count of 699.8 cells/µL. We measured TGF-β, LPS, and soluble CD14 (sCD14. marker of innate immune activation and microbial translocation) using immunoassays. SCFA (acetate, butyrate, and propionate) were measured using gas chromatography followed by mass spectrometry. Differences in the median levels of TGF-β, LPS, and SCFAs were evaluated using a Mann-Whitney test. We assessed the effects of LPS, SCFAs, and HIV infections in relationship with levels of TGF-β using multivariate fixed-effects regression analysis in R-statistical software. Results: PWH had significantly higher levels of TGF-β (4397 pg/mL vs. 1121 pg/mL, p=0.017), higher levels of LPS (38.97 pg/mL vs. 19.26 pg/mL, p&amp;lt;0.001), higher levels of sCD14 (1326 pg/mL vs. 1137 pg/mL, p=0.007), and significantly lower levels of butyrate (84.5 ng/mL vs. 62.0 ng/mL, p&amp;lt;0.001). Higher levels of TGF-b were associated with higher levels of LPS (rho=0.38, p=0.017) and higher levels of sCD14 (rho=0.27, p=0.016) these relationships remain significant after adjusting for HIV status (p&amp;lt;0.001). Conclusion: Our findings suggest that microbial products in blood plasma can contribute to higher cancer risk in Puerto Rican PWH and may represent potential novel biomarkers for cancer prevention. Citation Format: Jurelis Torres Reyes, Tanner L. Shull, Gabriel Borges-Velez, Veronica S. Sanchez Gonzalez, Jeannette L. Salgado Montilla, Josue Perez Santiago. Higher levels of LPS in blood plasma as potential novel biomarker for cancer risk in Puerto Rican people living with HIV [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2441.

XX sex chromosome complement modulates immune responses to heat-killed Streptococcus pneumoniae immunization in a microbiome-dependent manner.

Differences in male vs. female immune responses are well-documented and have significant clinical implications. While the immunomodulatory effects of sex hormones are well established, the contributions of sex chromosome complement (XX vs. XY) and gut microbiome diversity on immune sexual dimorphisms have only recently become appreciated. Here we investigate the individual and collaborative influences of sex chromosome complements and gut microbiota on humoral immune activation. Male and female Four Core Genotype (FCG) mice were immunized with heat-killed Streptococcus pneumoniae (HKSP). Humoral immune responses were assessed, and X-linked immune-related gene expression was evaluated to explain the identified XX-dependent phenotype. The functional role of Kdm6a, an X-linked epigenetic regulatory gene of interest, was evaluated ex vivo using mitogen stimulation of B cells. Additional influences of the gut microbiome on sex chromosome-dependent B cell activation was also evaluated by antibiotically depleting gut microbiota prior to HKSP immunization. Reconstitution of the depleted microbiome with short-chain fatty acid (SCFA)-producing bacteria tested the impact of SCFAs on XX-dependent immune activation. XX mice exhibited higher HKSP-specific IgM-secreting B cells and plasma cell frequencies than XY mice, regardless of gonadal sex. Although Kdm6a was identified as an X-linked gene overexpressed in XX B cells, inhibition of its enzymatic activity did not affect mitogen-induced plasma cell differentiation or antibody production in a sex chromosome-dependent manner ex vivo. Enhanced humoral responses in XX vs. XY immunized FCG mice were eliminated after microbiome depletion, indicating that the microbiome contributes to the identified XX-dependent immune enhancement. Reconstituting microbiota-depleted mice with select SCFA-producing bacteria enhanced fecal SCFA concentrations and increased humoral responses in XX, but not XY, FCG mice. However, exposure to the SCFA propionate alone did not enhance mitogenic B cell stimulation in ex vivo studies. FCG mice have been used to assess sex hormone and sex chromosome complement influences on various sexually dimorphic traits. The current study indicates that the gut microbiome impacts humoral responses in an XX-dependent manner, suggesting that the collaborative influence of gut bacteria and other sex-specific factors should be considered when interpreting data aimed at delineating the mechanisms that promote sexual dimorphism.

Lactobacillus paracasei ZFM54 alters the metabolomic profiles of yogurt and the co-fermented yogurt improves the gut microecology of human adults

Gut microbiota imbalance could lead to various diseases, making it important to optimize the structure of the gut flora in adults. Lactobacillus paracasei ZFM54 is a bacteriocin- and folic acid-producing Lactobacillus strain. Herein, L. paracasei ZFM54 was used as the potentially probiotic bacterium to ferment milk together with a yogurt starter. We optimized the fermentation conditions, and the obtained yogurts were then subjected to volatile and nonvolatile metabolome analysis, showing that L. paracasei ZFM54 can not only improve the acidity, water holding capacity and live lactic acid bacteria counts, but also improve many volatile acid contents and increase some beneficial nonvolatile metabolites, such as N-ethyl glycine and l-lysine, endowing the yogurt with more flavor and better function. The regulatory effects of the co-fermented yogurt on the intestinal microecology of volunteers were investigated by 16S rRNA sequencing and short-chain fatty acid (SCFA) analysis after consuming the yogurt for a 2-wk period, showing a better effect to increase the relative abundance of beneficial bacteria such as Ruminococcus and Alistipes, decrease harmful bacteria (Escherichia-Shigella and Enterobacter), and enhance the production of SCFA (acetate, propionate, and butyric acid) compared with the control yogurt. We found that L. paracasei ZFM54 can significantly improve the health benefits of yogurt, laying the foundation for its commercial application in improving gut microbiota.

Metabolic rescue of α-synuclein-induced neurodegeneration through propionate supplementation and intestine-neuron signaling in C. elegans

Microbial metabolites that can modulate neurodegeneration are promising therapeutic targets. Here, we found that the short-chain fatty acid propionate protects against α-synuclein-induced neuronal death and locomotion defects in a Caenorhabditis elegans model of Parkinson's disease (PD) through bidirectional regulation between the intestine and neurons. Both depletion of dietary vitamin B12, which induces propionate breakdown, and propionate supplementation suppress neurodegeneration and reverse PD-associated transcriptomic aberrations. Neuronal α-synuclein aggregation induces intestinal mitochondrial unfolded protein response (mitoUPR), which leads to reduced propionate levels that trigger transcriptional reprogramming in the intestine and cause defects in energy production. Weakened intestinal metabolism exacerbates neurodegeneration through interorgan signaling. Genetically enhancing propionate production or overexpressing metabolic regulators downstream of propionate in the intestine rescues neurodegeneration, which then relieves mitoUPR. Importantly, propionate supplementation suppresses neurodegeneration without reducing α-synuclein aggregation, demonstrating metabolic rescue of neuronal proteotoxicity downstream of protein aggregates. Our study highlights the involvement of small metabolites in the gut-brain interaction in neurodegenerative diseases.

Systematic review of the association between short-chain fatty acids and allergic diseases.

We performed a systematic review to investigate the current evidence on the association between allergic diseases and short chain fatty acids (SCFAs), which are microbially produced and suggested as one mechanism on how gut microbiome affects the risk of allergic diseases. Medline, Embase and Web of Science were searched from data inception until September 2022. We identified 37 papers, of which 17 investigated prenatal or early childhood SCFAs and the development of allergic diseases in childhood, and 20 assessed SCFAs in patients with pre-existing allergic diseases. Study design, study populations, outcome definition, analysis method and reporting of the results varied between papers. Overall, there was some evidence showing that the three main SCFAs (acetate, propionate and butyrate) in the first few years of life had a protective effect against allergic diseases, especially for atopic dermatitis, wheeze or asthma and IgE-mediated food allergy in childhood. The association between each SCFA and allergic disease appeared to be different by disease and the age of assessment. Further research that can determine the potentially timing specific effect of each SCFA will be useful to investigate how SCFAs can be used in treatment or in prevention against allergic diseases.