Fecal Short-Chain Fatty Acids to Predict Prediabetes and Type 2 Diabetes Risk: An Exploratory Cross-Sectional Study

Type 1 diabetes (T1D) is expected to cause significant changes in the serum proteome; however, few studies have systematically assessed the proteomic profile change associated with the disease. In this study, a semiquantitative spectral counting-based two dimensional liquid chromatography mass spectrometry platform was used to analyze serum samples from T1D patients and controls. In this discovery phase, significant differences were found for 21 serum proteins implicated in inflammation, oxidation, metabolic regulation, and autoimmunity. To assess the validity of these findings, six candidate proteins including adiponectin, insulin-like growth factor binding protein 2, serum amyloid protein A, C-reactive protein, myeloperoxidase, and transforming growth factor beta induced were selected for subsequent immune assays for 1139 T1D patients and 848 controls. A series of statistical analyses using cases and controls matched for age, sex, and genetic risk confirmed that T1D patients have significantly higher serum levels for four of the six proteins: adiponectin (odds ratio (OR) = 1.95, p = 10(-27)), insulin-like growth factor binding protein 2 (OR = 2.02, p < 10(-20)), C-reactive protein (OR = 1.13, p = 0.007), serum amyloid protein A (OR = 1.51, p < 10(-16)); whereas the serum levels were significantly lower in patients than controls for the two other proteins: transforming growth factor beta induced (OR = 0.74, p < 10(-5)) and myeloperoxidase (OR = 0.51, p < 10(-41)). Compared with subjects in the bottom quartile, subjects in the top quartile for adiponectin (OR = 6.29, p < 10(-37)), insulin-like growth factor binding protein 2 (OR = 7.95, p < 10(-46)), C-reactive protein (OR = 1.38, p = 0.025), serum amyloid protein A (OR = 3.36, p < 10(-16)) had the highest risk of T1D, whereas subjects in the top quartile of transforming growth factor beta induced (OR = 0.41, p < 10(-11)) and myeloperoxidase (OR = 0.10, p < 10(-43)) had the lowest risk of T1D. These findings provided valuable information on the proteomic changes in the sera of T1D patients.

Short chain fatty acids (SCFA) produced during the colonic fermentation of dietary fiber may reduce risk for obesity and type 2 diabetes. Our objectives were to determine if fecal SCFA concentration and absorption differ and/or are correlated in lean and overweight/obese (OW) subjects. Lean (n=11) and OW (n=11) subjects were recruited. After completing a 3‐day diet record subjects provided a fresh fecal sample to measure SCFA concentration. Subjects then inserted a rectal dialysis bag filled with 10ml of SCFA solution for 30 min. The procedures were repeated after two weeks. Fecal SCFA was higher in OW than lean subjects (80±6 vs 56±6 mmol/kg, p=0.02). The rate of SCFA absorption was similar and proportional to the SCFA concentration in the dialysis bag in both groups. There was a significant positive correlation between the SCFA absorption and fecal SCFAs for the OW group (r 0.44, p=0.04), but not for the lean group (r −0.22, p= 0.33) (difference in slopes, p=0.03). Since SCFA absorption from the dialysis bag was concentration dependent in the groups, OW people may absorb more colonic SCFA from their own feces. Within the OW group, the positive correlation between SCFA absorption and fecal SCFA concentration may be a result of upregulation of transporter expression for ionic diffusion.This work was supported by a grant from the Canadian Institutes for Health Research.

Colonic bacterial populations are thought to have a role in the development of colorectal cancer with some protecting against inflammation and others exacerbating inflammation. Short-chain fatty acids (SCFAs) have been shown to have anti-inflammatory properties and are produced in large quantities by colonic bacteria that produce SCFAs by fermenting fiber. We assessed whether there was an association between fecal SCFA concentrations and the presence of colonic adenomas or carcinomas in a cohort of individuals using 16S rRNA gene and metagenomic shotgun sequence data. We measured the fecal concentrations of acetate, propionate, and butyrate within the cohort and found that there were no significant associations between SCFA concentration and tumor status. When we incorporated these concentrations into random forest classification models trained to differentiate between people with healthy colons and those with adenomas or carcinomas, we found that they did not significantly improve the ability of 16S rRNA gene or metagenomic gene sequence-based models to classify individuals. Finally, we generated random forest regression models trained to predict the concentration of each SCFA based on 16S rRNA gene or metagenomic gene sequence data from the same samples. These models performed poorly and were able to explain at most 14% of the observed variation in the SCFA concentrations. These results support the broader epidemiological data that questions the value of fiber consumption for reducing the risks of colorectal cancer. Although other bacterial metabolites may serve as biomarkers to detect adenomas or carcinomas, fecal SCFA concentrations have limited predictive power.IMPORTANCE Considering that colorectal cancer is the third leading cancer-related cause of death within the United States, it is important to detect colorectal tumors early and to prevent the formation of tumors. Short-chain fatty acids (SCFAs) are often used as a surrogate for measuring gut health and for being anticarcinogenic because of their anti-inflammatory properties. We evaluated the fecal SCFA concentrations of a cohort of individuals with different colonic tumor burdens who were previously analyzed to identify microbiome-based biomarkers of tumors. We were unable to find an association between SCFA concentration and tumor burden or use SCFAs to improve our microbiome-based models of classifying people based on their tumor status. Furthermore, we were unable to find an association between the fecal community structure and SCFA concentrations. Our results indicate that the association between fecal SCFAs, the gut microbiome, and tumor burden is weak.

The gut microbiome is associated with obesity, mainly mediated by bacteria-produced short-chain fatty acids (SCFAs). It is unknown how SCFA concentrations are associated with the phenotypes metabolically healthy normal weight (MHNW), metabolically unhealthy normal weight (MUNW), metabolically healthy obese/overweight (MHO), and metabolically unhealthy obese/overweight (MUO). We compared plasma and fecal SCFA concentrations among adult women categorized according to the metabolic phenotypes mentioned above and examined associations between SCFA and adiposity and components of energy and glucose homeostasis. This was a cross-sectional study involving 111 participants. Body composition was assessed by DEXA. Energy and glycemic homeostasis were assessed by the standard mixed-meal tolerance test coupled with indirect calorimetry. SCFAs were quantified by gas chromatography and mass spectrometry. Only plasma propionate was increased in the MHNW phenotype compared to the MHO and MUO phenotypes [p < 0.05]. Fecal propionate and butyrate concentrations and plasma propionate concentrations were inversely associated with total and visceral adiposity [p < 0.05]. Fecal and plasma SCFA concentrations were associated with reduced glucose, insulin and HbA1c levels, increased fasting and postprandial GLP-1 levels; and more preserved beta-cell function [p < 0.05]. Fecal and plasma SCFA concentrations were positively correlated with resting energy expenditure and lipid oxidation rate and inversely correlated with the oxidation rate of carbohydrates [p < 0.05]. These findings reinforce the concept that fecal and plasma SCFA concentrations are linked to specific components of energy and glucose homeostasis; and body adiposity. However, it was not possible to discriminate the different metabolic phenotypes of adiposity based on the determination of fecal SCFA concentrations.

Short-chain fatty acids (SCFAs) produced by gut microbiota are reduced in feces but paradoxically increased in plasma of patients with Parkinson's disease (PD), which may stem from intestinal wall leakage. Gut function should be taken into consideration when conducting microbial-metabolite research. The objective was to investigate synchronous changes of SCFAs in feces and plasma of patients with PD, taking constipation as a confounder to better disentangle the SCFA metabolism exclusively associated with PD. The concentrations of fecal and plasma SCFAs in 33 healthy control subjects and 95 patients with PD were measured using liquid and gas chromatography mass spectrometry, respectively. Patients with PD were divided into patients with PD without constipation (n=35) and patients with PD with constipation (n=60). Gut-blood barrier (GBB) permeability was assessed by plasma/fecal ratio of SCFA concentrations and fecal α1-antitrypsin concentration. Patients with PD displayed decreased concentrations of fecal acetic, propionic, and butyric acid and increased concentrations of plasma acetic and propionic acid. Fecal acetic, isobutyric, and isovaleric acid were lower and plasma acetic and propionic acid were higher in patients with PD with constipation than in patients with PD without constipation. Constipation aggravated GBB permeability in patients with PD. Combined fecal and plasma SCFAs could discriminate patients with PD from healthy control subjects. Fecal SCFAs, except propionic acid, were negatively correlated with disease severity, while plasma acetic, propionic, and valeric acid showed a positive correlation. Our study showed alterations of fecal and plasma SCFAs in patients with PD that were associated with an impaired GBB and might be aggravated by constipation. © 2022 International Parkinson and Movement Disorder Society.

BackgroundMultiple Sclerosis (MS) is an autoimmune-mediated disease of the central nervous system. Experimental data suggest a role of intestinal microbiota and microbial products such as short-chain fatty acids (SCFAs) in the pathogenesis of MS. A recent clinical study reported beneficial effects (mediated by immunomodulatory mechanisms) after oral administration of the SCFA propionate in MS patients. Based on available evidence, we investigated whether SCFAs and the fecal inflammation marker calprotectin are altered in MS.Methods76 subjects (41 patients with relapsing–remitting MS and 35 age-matched controls) were investigated in this case–control study. All subjects underwent clinical assessment with established clinical scales and provided fecal samples for a quantitative analysis of fecal SCFA and fecal calprotectin concentrations. Fecal markers were compared between MS patients and controls, and were analyzed for an association with demographic as well as clinical parameters.ResultsMedian fecal calprotectin concentrations were within normal range in both groups without any group-specific differences. Fecal SCFA concentrations showed a non-significant reduction in MS patients compared to healthy subjects. Female subjects showed significantly reduced SCFA concentrations compared to male subjects.ConclusionsIn our cohort of MS patients, we found no evidence of an active intestinal inflammation. Yet, the vast majority of the investigated MS patients was under immunotherapy which might have affected the outcome measures. The sex-associated difference in fecal SCFA concentrations might at least partially explain female predominance in MS. Large-scale longitudinal studies including drug-naïve MS patients are required to determine the role of SCFAs in MS and to distinguish between disease-immanent effects and those caused by the therapeutic regime.

BackgroundEvidence is accruing to suggest that microbiota-gut-brain signalling plays a regulatory role in cardiorespiratory physiology. Chronic intermittent hypoxia (CIH), modelling human sleep apnoea, affects gut microbiota composition and elicits cardiorespiratory morbidity. We investigated if treatment with prebiotics ameliorates cardiorespiratory dysfunction in CIH-exposed rats.MethodsAdult male rats were exposed to CIH (96 cycles/day, 6.0% O2 at nadir) for 14 consecutive days with and without prebiotic supplementation (fructo- and galacto-oligosaccharides) beginning two weeks prior to gas exposures.FindingsCIH increased apnoea index and caused hypertension. CIH exposure had modest effects on the gut microbiota, decreasing the relative abundance of Lactobacilli species, but had no effect on microbial functional characteristics. Faecal short-chain fatty acid (SCFA) concentrations, plasma and brainstem pro-inflammatory cytokine concentrations and brainstem neurochemistry were unaffected by exposure to CIH. Prebiotic administration modulated gut microbiota composition and diversity, altering gut-metabolic (GMMs) and gut-brain (GBMs) modules and increased faecal acetic and propionic acid concentrations, but did not prevent adverse CIH-induced cardiorespiratory phenotypes.InterpretationCIH-induced cardiorespiratory dysfunction is not dependant upon changes in microbial functional characteristics and decreased faecal SCFA concentrations. Prebiotic-related modulation of microbial function and resultant increases in faecal SCFAs were not sufficient to prevent CIH-induced apnoea and hypertension in our model. Our results do not exclude the potential for microbiota-gut-brain axis involvement in OSA-related cardiorespiratory morbidity, but they demonstrate that in a relatively mild model of CIH, sufficient to evoke classic cardiorespiratory dysfunction, such changes are not obligatory for the development of morbidity, but may become relevant in the elaboration and maintenance of cardiorespiratory morbidity with progressive disease.FundingDepartment of Physiology and APC Microbiome Ireland, University College Cork, Ireland. APC Microbiome Ireland is funded by Science Foundation Ireland, through the Government's National Development Plan.

High-sensitivity C-reactive protein (hs-CRP) is a widely used clinical biomarker of systemic inflammation, implicated in many chronic conditions, including type 1 diabetes (T1D). Despite the increasing emphasis on dietary intake as a modifiable risk factor for systemic inflammation, the association of hs-CRP with fruit and vegetable consumption is relatively underexplored in T1D. To address this gap, we investigated the longitudinal associations of dietary pattern-derived fruit and vegetable scores with hs-CRP in adults with and without T1D. Additionally, we examined the impact of berry consumption as a distinct food group. Data were collected in the Coronary Artery Calcification in Type 1 Diabetes study over two visits that were three years apart. At each visit, participants completed a food frequency questionnaire, and hs-CRP was measured using a particle-enhanced immunonephelometric assay. Mixed effect models were used to examine the three-year association of fruit and vegetable scores with hs-CRP. Adjusted models found a significant inverse association between blueberry intake and hs-CRP in the nondiabetic (non-DM) group. Dietary Approaches to Stop Hypertension- and Alternative Healthy Eating Index-derived vegetable scores were also inversely associated with hs-CRP in the non-DM group (all p-values ≤ 0.05). Conversely, no significant associations were observed in the T1D group. In conclusion, dietary pattern-derived vegetable scores are inversely associated with hs-CRP in non-DM adults. Nonetheless, in T1D, chronic hyperglycemia and related metabolic abnormalities may override the cardioprotective features of these food groups at habitually consumed servings.

In modern societies obesity has become a serious issue which must be urgently addressed. The health implications of neglected obesity are substantial, as not only does it affect individuals' everyday lives, but it also leads to significantly increased mortality due to the development of several disorders such as type-2 diabetes, cardiovascular diseases, cancers, and depression. The objective of this research was to investigate the alterations in selected health markers caused by overweight and obesity in children. The measured parameters were the activity of the fecal enzymes, the concentration of short-chain fatty acids (SCFAs), and the concentration of branched-chain fatty acids (BCFAs). The activity of the fecal enzymes, specifically α-glucosidase, α-galactosidase, β-glucosidase, β-galactosidase, and β-glucuronidase, was determined using spectrophotometry at a wavelength of 400 nm. Furthermore, concentrations of lactic acid, SCFAs (formic, acetic, propionic, butyric, and valeric acids), and BCFAs (isobutyric and isovaleric acids) were determined using the HPLC method. The obtained results reveal that obese children have different fecal enzyme activity and a different profile of fatty acids from children of normal weight. The group of obese children, when compared to children of normal weight, had increased concentrations of BCFAs (p < 0.05) and higher activity of potentially harmful enzymes such as β-glucosidase and β-glucuronidase (p < 0.05). In comparison, children of normal weight exhibited significantly increased concentrations of lactic acid and SCFAs (especially formic and butyric acids) (p < 0.05). Furthermore, their α-glucosidase and α-galactosidase activity were higher when compared to the group of obese children (p < 0.05). These results suggest that the prevalence of obesity has a significant impact on metabolites produced in the gastrointestinal tract, which might result in a higher chance of developing serious diseases.

Background: Allogeneic hematopoietic cell transplantation (allo-HCT) can be a curative therapy for patients with hematological malignancies. However, allo-HCT poses a significant risk for post-transplant mortality due to graft-versus-host disease (GVHD), which is associated with loss of beneficial intestinal microbiota and decrease of microbial metabolites. In addition, dietary fiber can modulate the intestinal microbiome and the production of short-chain fatty acids (SCFAs), which are microbial metabolites associated with intestinal homeostasis. Therefore, we hypothesized that a high-fiber diet is associated with an increase of beneficial commensals, higher concentrations of SCFAs, and decreased risk of GVHD. Methods: We collected dietary data and fecal samples from 73 allo-HCT patients (GVHD n=45, No-GVHD n=28) at Memorial Sloan Kettering Cancer Center, collected longitudinally throughout the allo-HCT course, and performed 16s rRNA, shotgun metagenomic sequencing, and gas chromatography mass spectrometry (n=311). We assessed the α-diversity, microbiome composition, and concentrations of fecal SCFAs in response to fiber intake. We also tested different concentrations of dietary fiber (0%, 6%, 12% and 40%) in a preclinical GVHD model (C57BL/6J into BALB/c, n=30 per group, n=180 total) and assessed GVHD lethality and fecal microbial composition. Results: We found that in allo-HCT patients, fiber intake significantly correlated with microbial α-diversity (R=0.3, p=0.01) and patients with a higher fiber diet had a significantly higher microbial α-diversity when compared to the low fiber cohort (p&amp;lt;0.001). Remarkably, the decrease in dietary fiber post-allo-HCT correlated with a significant reduction in the fecal concentrations of SCFAs in the GVHD group (n=14), butyrate (p=0.003), propionate (p=0.01), and acetate (p=0.004), that was not significant in the No-GVHD cohort (n=28), indicating that low dietary fiber could lead to lower production of bacterial metabolites in GVHD. In addition, mice receiving a fiber-rich diet (12%) had a significant reduction in GVHD lethality (p=0.02) compared to mice receiving lower or higher fiber (0%, 6%, 40%). A 12% fiber diet also resulted in higher microbial α-diversity (p=0.02) and a significant decrease in Enterococcus faecalis (p=0.05), a pathogen associated with worse GVHD mortality in mice and humans. Conclusions: Our study demonstrates that a) higher fiber intake in patients after allo-HCT is associated with an increase in α-diversity and SCFA concentrations, and b) optimal fiber consumption in pre-clinical GVHD models leads to an increase in α-diversity, a decrease in pathogen mono-domination, and more importantly, a decrease in GVHD lethality. These results suggest that dietary fiber could be used in the prevention of GVHD. Citation Format: Jenny Paredes, Peter Adintori, Anqi Dai, Ruben J. Faustino Ramos, Teng Fei, Harold Elias, Marina Burgos da Silva, Romina Ghale, Charlotte Pohl, Justin Cross, Oriana Miltiadous, Marcel van den Brink. Correlations of dietary fiber with intestinal microbiome and outcomes in allogeneic hematopoietic cell transplantation [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 643.

Double diabetes: the cardiovascular implications of combining type 1 with type 2 diabetes

Human Breast Milk and Infant Formulas Differentially Modify the Intestinal Microbiota in Human Infants and Host Physiology in Rats

The purpose of this study was to assess the practical implications of supplementing soluble fiber in the diet of dogs. Dogs with a history of managed or active chronic enteropathy were randomized to receive either wheat dextrin (fiber group) or maltodextrin (placebo group) mixed with food once daily for 28 days. Owners recorded a daily fecal score one week prior to and during the supplementation period. Shallow shotgun sequencing, quantitative PCR abundances of core bacterial taxa, and short-chain fatty acid (SCFA) concentrations via gas chromatography/mass spectrometry were performed on fecal samples collected before and after supplementation. Seventeen dogs completed the study (fiber group: nine dogs; placebo group: eight dogs). The change in fecal score differed between groups, with the fiber group developing softer stools (p = 0.03). Alpha diversity, quantified PCR abundances of the SCFA-producing taxa, and fecal SCFA concentrations were not different after supplementation in either group. Fecal microbial communities differed between baseline and day 28 for fiber and placebo groups (p = 0.02, respectively); however, the size effect (ANOSIM R = 0.18 and R = 0.26, respectively) was minimal. In this small group of dogs fed variable commercial diets, the additional intake of wheat dextrin powder supplement was well accepted, but had minimal discernable clinical benefit, and could soften stools.

Introduction: Total pancreatectomy with islet autotransplantation (TPIAT) is an effective treatment option for nondiabetic patients with intractable chronic pancreatitis. The outcome and potential benefits for prediabetic and diabetic patients are less well established. Method: Thirty-four patients underwent TPIAT were retrospectively divided into 3 groups according to pre-operative glycemic control: diabetes mellitus (DM) (n=5, 15%), Pre-DM (n=11, 32%) and Non-DM (n=18, 54%). Results: Preoperative fasting c-peptide was detectable and similar in all 3 groups. Islet mass in the DM group was comparable to Pre-DM and Non-DM groups: (median 191,800), 111,800 and 232,000, respectively). Patients received islet mass of over the target level of 2,000 IEQ/kg in Pre-DM and DM at lower but clinically meaningful rates compared to the Non-DM group 45% (5/11) and 60% (3/5) for a combined 50% (8/16) rate, respectively, compared to 83% (15/18) for the non-DM group. At 1 year, fasting c-peptide and HbA1c did not differ between DM and Pre-DM groups but c-peptide was significantly higher in Non-DM. Islet transplantation failed (negative c-peptide) only in one patient. Preoperatively, all patients experienced pancreatic pain with daily opioid dependence in 60-70%. Pancreatic-type pain gradually subsided completely in all groups with no differences in other painful somatic symptoms. Conclusions: Patients with diabetes and measurable preoperative c-peptide can achieve similar benefit from TPIAT, with comparable outcomes to prediabetic and nondiabetic patients including pain relief. Not surprisingly, endocrine outcomes for diabetic and prediabetic patients are substantially worse than in those with normal preoperative glucose control. Disclosure P.J. Bachul: None. P. Borek: None. R. Anteby: None. L. Basto: None. L. Perea: None. K. Golab: None. L. Wang: None. M.L. Tibudan: None. A. Perez-Gutierrez: None. M. Komorniczak: None. S. Nagpal: None. A.C. Lucander: None. M. Dimitrov: None. J. Fung: None. J.B. Matthews: None. P. Witkowski: None.

Background/Objectives:High dietary fibre intakes may protect against obesity by influencing colonic fermentation and the colonic microbiota. Though, recent studies suggest that increased colonic fermentation contributes to adiposity. Diet influences the composition of the gut microbiota. Previous research has not evaluated dietary intakes, body mass index (BMI), faecal microbiota and short chain fatty acid (SCFA) in the same cohort. Our objectives were to compare dietary intakes, faecal SCFA concentrations and gut microbial profiles in healthy lean (LN, BMI⩽25) and overweight or obese (OWOB, BMI>25) participants.Design:We collected demographic information, 3-day diet records, physical activity questionnaires and breath and faecal samples from 94 participants of whom 52 were LN and 42 OWOB.Results:Dietary intakes and physical activity levels did not differ significantly between groups. OWOB participants had higher faecal acetate (P=0.05), propionate (P=0.03), butyrate (P=0.05), valerate (P=0.03) and total short chain fatty acid (SCFA; P=0.02) concentrations than LN. No significant differences in Firmicutes to Bacteroides/Prevotella (F:B) ratio was observed between groups. However, in the entire cohort, Bacteroides/Prevotella counts were negatively correlated with faecal total SCFA (r=−0.32, P=0.002) and F:B ratio was positively correlated with faecal total SCFA (r=0.42, P<0.0001). Principal component analysis identified distinct gut microbiota and SCFA–F:B ratio components, which together accounted for 59% of the variation. F:B ratio loaded with the SCFA and not with the microbiota suggesting that SCFA and F:B ratio vary together and may be interrelated.Conclusions:The results support the hypothesis that colonic fermentation patterns may be altered, leading to different faecal SCFA concentrations in OWOB compared with LN humans. More in-depth studies looking at the metabolic fate of SCFA produced in LN and OWOB participants are needed in order to determine the role of SCFA in obesity.