To Örebro University

BACKGROUND: Dietary patterns influencing systemic levels of inflammation have been proposed and investigated as possible determinants of cancer risk. We evaluated the association between the anti-inflammatory potential of diet and the risk of bladder cancer (BC).

METHODS: The Anti-Inflammatory Diet Index (AIDI), composed of 16 food groups (11 anti- and 5 pro-inflammatory), was used to score dietary patterns in N=79,292 individuals derived from the Cohort of Swedish Men (COSM, established in 1997) and the Swedish Mammography Cohort (SMC, established in 1987). Dietary information was collected in 1997 and 2009; repeated-measure analyses used a cumulative-average AIDI. Incident BC cases were identified from the Swedish Cancer Register using ICD-10 code C67, and baseline study questionnaire was used to assess covariates. We estimated multivariable hazard ratios across AIDI quartiles using Cox models.

RESULTS: After a 22-year follow-up, 1,165 individuals were diagnosed with BC, of whom 249 had non-muscle invasive (NMI) BC, 201 muscle invasive (MI) BC and 715 unknown stage. In repeated-measures analyses, the highest anti-inflammatory quartile (Q4) was associated with lower BC risk compared with the lowest quartile (Q1) (HR 0.74, 95% CI 0.61-0.89). Stratifying for tumour stage, there was a clear association between AIDI-score and MIBC (HR 0.35, 95% CI 0.22-0.57), but not for NMIBC (HR 0.86, 95% CI 0.57-1.28).

CONCLUSIONS: An anti-inflammatory dietary pattern was associated with lower BC risk, with the clearest association for MIBC. IMPACT: These findings support the role of dietary inflammation in BC aetiology and suggest that promoting anti-inflammatory dietary patterns could contribute to cancer prevention strategies.

Intestinal luminal microbial metabolites affect tryptophan and serotonin metabolism, and cross or modify the blood-brain barrier (BBB). Understanding those mechanisms further necessitates integrated gut-brain axis model systems. Using an ex vivo-in vitro approach, H2O2-stressed or non-stressed human dermal fibroblasts - representing the BBB - are cultured with serosal fluids of healthy or irritable bowel syndrome human colonic biopsies collected from Ussing chamber experiments, after participant's colon was exposed to butyrate in vivo, fecal fiber fermentation or control supernatant ex vivo. Culturing fibroblasts with serosal fluids does not compromise viability or have cytotoxic effects. Serosal fluids alone do not alter expression of tryptophan-related large amino acid membrane transporter genes and proteins, nor their activity (i.e., tryptophan uptake). However, adding serosal fluids to fibroblasts prior to oxidative stress indicate a protective role. This new model allows investigation of direct effects of serosal content on BBB-representing fibroblasts and is highly promising for more personalized applications.

Shifting to a plant-based diet naturally alters protein source choices. In many countries, protein from yellow pea is widely used as a main ingredient in meat alternatives. Still, its biological effects, especially regarding gastrointestinal health, remain incompletely understood. The aim of our study was to investigate how a weekly increase in the intake of a well-characterized pea protein isolate affects surrogate markers of health, fecal short-chain fatty acids and gut microbiota composition in healthy individuals. Male and female adults (N = 29) participated in this exploratory intervention study. A 4-week pre-intervention period for questionnaires and fecal samples collection was followed by a 4-week supplementation. Participants consumed isolated pea protein in weekly increasing amounts, starting from 0.25 g per kg body mass per day in week 5 to 1.00 g per kg body mass per day in week 8. Questionnaire data, fecal samples as well as fasting blood and 24 h urine samples were collected weekly. Data from biological samples and questionnaires confirmed a healthy study population and compliance. Fecal calprotectin levels significantly increased only in a subset of participants, which was accompanied by higher fecal water cytotoxicity in vitro. Short-chain fatty acids mainly rose in those subjects with stable calprotectin levels. Relative abundances of Limosilactobacillus frumenti, Odoribacter splanchnicus and Lactobacillus crispatus increased significantly in the total population during the intervention while the relative abundance of Bifidobacterium longum and Bifidobacterium catenulatum decreased. Our results indicate that an increased intake of pea protein isolate affects the growth of certain beneficial bacterial strains and differentially influences markers related to gut inflammation in healthy individuals.

Pectins are a class of highly fermentable dietary fibers that modulate the gut microbiota, with biological effects that vary depending on ripening stage and molecular structure. This study investigated the impact of ripe and unripe papaya dietary fibers on gut microbiota composition in rats subjected to a chemically-induced colon carcinogenesis model. Male Wistar rats received AOM injections and were fed with regular chow, ripe papaya, and unripe papaya dietary fibers. After 10 weeks, aberrant crypt foci (ACF), short-chain fatty acids (SCFA) production, and intestinal microbiota composition were analyzed. Both pectins reduced the number of ACF with a single crypt, whereas only ripe papaya fiber intake reduced ACF with more than one crypt. Acetate production was higher in animals fed unripe papaya pectin, propionate increased for both pectins, and total SCFA was higher only in the unripe papaya compared to the AOM group. Ripe papaya pectin increased alpha and beta diversity of the microbiota, showing a profile similar to that of the negative control, whereas unripe papaya clustered closer to the AOM group. Ripe papaya pectin increased the abundance of several probiotic Lactobacillus species, while unripe papaya pectin increased Romboutsia abundance; the AOM treatment increased Mediterraneibacter. Overall, these results suggest that, depending on the ripening stage, papaya pectins can differentially modulate SCFA production and the microbiota profile, thereby contributing to the attenuation of early preneoplastic lesions in the colon.

Per- and polyfluoroalkyl substances (PFAS) are persistent environmental contaminants that can disrupt human hepatic metabolism both directly and through alterations of the gut microbiota. However, the contribution of microbiota-mediated mechanisms to PFAS-induced hepatic dysfunction remains poorly understood. Here, we investigated how PFAS-modified gut microbial metabolites affect human hepatocyte metabolism using an in vitro colon fermentation model, supported by an in vivo mouse and in vitro human hepatocyte exposure studies. PFAS exposure altered the fecal metabolome in human colonic fermentations, particularly affecting pathways related to fatty acid, amino acid, vitamin, and mitochondrial metabolism. Fecal metabolomics from PFOA-exposed mice showed overlapping pathway-level alterations, including effects on fatty acid, bile acid, and steroid hormone metabolism, supporting the biological relevance of the in vitro findings. Exposure of HepaRG hepatocytes to control fermentation extracts markedly altered lipid profiles, confirming that gut-derived metabolites actively regulate hepatic metabolism. Notably, PFAS-exposed fermentation extracts induced distinct hepatocyte metabolic changes compared with PFAS-spiked control extracts, indicating effects driven by PFAS-modified microbial metabolites rather than direct PFAS carry-over. These changes included decreased acyl-carnitines and increased L-carnitine, consistent with altered fatty acid transport and mitochondrial β-oxidation. PFAS-modified extracts also altered bile acids, steroid metabolites, inosine, and sialic acid derivatives, suggesting broader alteration of bile acid signaling, endocrine-related metabolism, purine metabolism, glycoprotein turnover, and lipid-glucose homeostasis. These findings from our pilot study demonstrate that PFAS exposure reshapes gut microbial metabolite profiles with downstream consequences for hepatocyte metabolism. Our findings provide new mechanistic insight into how PFAS may contribute to metabolic disorders.

Irritable bowel syndrome (IBS) is a prevalent gastrointestinal disorder for which effective treatment strategies are insufficient. Butyrate, a microbiota-derived short-chain fatty acid believed to strengthen the intestinal barrier function, might be a potential new treatment option. This study aimed to investigate potential protective effects of acute in vivo butyrate exposure on intestinal barrier function in healthy subjects and patients with IBS. For this, we used an experimental colonoscopy-perfusion model for colon-specific butyrate delivery and adequate tissue sampling. Seventeen IBS and 17healthy subjects underwent a colonoscopy procedure exposing a predefined colonic area to 100mmol/L butyrate for 90 min in vivo. Mucosal biopsies collected pre- and post-butyrate exposure were stimulated in Ussing chambers with/without sodium deoxycholate (DC) to induce intestinal hyperpermeability. Intestinal permeability was measured by fluorescein isothiocyanate-dextran and horseradish peroxidase passage. DC-stimulation significantly increased para- and transcellular permeability in biopsies collected pre-butyrate exposure. DC-induced transcellular hyperpermeability was significantly alleviated in biopsies collected post-butyrate exposure compared to pre-exposure in patients with IBS (p = 0.034). In conclusion, we established a colonoscopy research model for colon-specific delivery and sampling and demonstrated acute protective effects of butyrate on transcellular intestinal permeability in patients with IBS. The results support butyrate's potential role in novel treatment strategies in IBS. Clinicaltrials.gov number: NCT05249023.

The intestinal microbiota is shaped by fiber-rich ingredients, such as unripe banana flour (UBF), high in resistant starch (RS). We investigated the effects of RS-rich UBF and inulin on gut microbiota and intestinal function in a double-blind, randomized, placebo-controlled pilot trial. Forty-eight healthy adults consumed maltodextrin (control), inulin, or UBF three times weekly for six weeks. Microbiota composition and function were analyzed using 16S rRNA gene sequencing and PICRUSt, alongside fecal short-chain fatty acids, blood biochemistry, and gastrointestinal parameters. We observed two microbiota clusters at baseline, one Prevotella-rich (P) and one Bacteroides-rich (B), with distinct responses to the interventions. Only cluster P subjects consuming UBF showed significant global microbiota shifts (weighted Unifrac Beta diversity, PERMANOVA p = 0.007) and major functional changes (533 KEGG orthologs, FDR < 0.05). Inulin produced modest modulation (19 KOs) on cluster P, and no effects were observed on cluster B. RS-rich UBF modulated gut microbiota in a composition-dependent manner, supporting the potential of microbiota-based stratification to improve dietary fiber interventions.

Dietary fibers (DF) from plant-based foods promote health benefits through their physicochemical properties and fermentation by the gut microbiota, often studied in relation to changes in gut microbiota profile and production of gut microbiota-derived metabolites. Here, we characterized structural motifs (i.e., oligomers) produced during DF breakdown upon colonic fermentation and explored their interaction with toll-like receptors (TLRs) present on the surface of human intestinal and immune system cells. Wheat arabinoxylan (WAX) was subjected to in vitro colonic fermentation, with its structural motifs identified and tracked throughout the fermentation process. Using carbohydrate-active enzymes, six well-defined fractions of arabinoxylans and linear xylans identified during colonic fermentation were produced and tested for interaction with tool-like receptors (TLR)2 and TLR4 via reporter cell assay. The results showed structure-dependent effects, with TLR2 inhibition and TLR4 activation varying based on the degree of polymerization and branching. Molecular docking confirmed that minor structural changes in oligomers structure significantly influenced these interactions. The study supports the hypothesis that oligomers and polysaccharides affect cell receptors through complex, multi-receptor interactions, and highlights the potential for enzymatic tailoring of DF to create functional ingredients with targeted effects on human health.

Oligosaccharides represent an important class of bioactive compounds with diverse structure-dependent functionalities. While traditionally investigated for prebiotic effects on gut microbiota, increasing evidence shows that they can also interact directly with intestinal and immune cell receptors (e.g., pattern recognition receptors, C-type lectin receptors, G-protein coupled receptors, and scavenger receptors), influencing inflammation, mucosal immunity, and epithelial barrier function. In a circular bioeconomy context, oligosaccharides offer an underexplored sustainable route for upcycling agro-industrial and forestry biomass by converting polysaccharides into structurally tailored products. This review synthesizes current knowledge on the direct effects of plant-derived oligosaccharides on host receptors and describes enzymatic and green chemistry-based methods for their production and extraction. We propose a new roadmap for oligosaccharide upcycling using assessments for their biological effects, characterization, standardization, and alignment with regulatory aspects. This enables translating receptor-active oligosaccharides from biomass utilization into innovative solutions for precision nutrition and sustainable functional food development.

Pectins are a class of soluble polysaccharides that can have anticancer properties through several mechanisms. This study aimed to characterize the molecular structure of water-soluble fractions (WSF) derived from ripe and unripe papayas and assess their biological effects in two models: the 3D colon cancer spheroids to measure cell viability and cytotoxicity, and the in vivo model to investigate the inhibition of preneoplastic lesions in rats. WSF yield was slightly higher in ripe papaya, and both samples mainly consisted of pectin. Both pectins inhibited the growth of colon cancer HT29 and HCT116 spheroids. Unripe pectin disturbed HT29/NIH3T3 spheroid formation, decreased HCT116 spheroid viability, and increased spheroid cytotoxicity. Ripe pectin had a more substantial effect on the reduction of spheroid viability for HT29 spheroids. Furthermore, in vivo experiments on a rat model revealed a decrease in aberrant crypt foci (ACF) formation for both pectins and increased apoptosis in colonocytes for ripe papaya pectins. The results suggest potential anticancer properties of papaya pectin, with ripe pectin showing a higher potency.