Biology subjects

Brummer, R. J.

Publications and source records attributed to Brummer, R. J..

3 recordsLinked to original sources

bioRxiv2026

The expression of colonic keratins is elevated in IBD, reduced in microscopic colitis, and unchanged in IBS : a retrospective study

BackgroundKeratins, a major subgroup of intermediate filament proteins, play a critical role in maintaining epithelial barrier and intracellular epithelial integrity. Studies have demonstrated possible links between inflammatory signaling and colonic keratins type II K8, and type I K18, K19 and K20, in animal models of colitis, and in patients with Inflammatory Bowel Disease (IBD). K7 is de novo expressed in patients with the IBD subtypes Ulcerative Colitis (UC) and Crohns Disease (CD). However, the histopathological roles of colonocyte keratins across IBD, microscopic colitis (MC), and Irritable Bowel Syndrome (IBS) remain poorly understood. Given the established utility as biomarkers in cancer diagnostics, we investigated whether keratin expression patterns could be used to distinguish inflammatory and functional colonic disorders. MethodsBiobank samples from patients with IBD (n=27), MC (n=18), IBS (n=32) and healthy controls (n=31), were collected and immunohistochemically stained for K7, K8, K18, K19, and K20. Digital image analysis quantified staining intensities, which were correlated with histopathological severity scores and clinical parameters. ResultsColonic keratin expression was significantly elevated in IBD, particularly in UC, while they were decreased in MC, and unaltered in IBS. Notably, K8 and K19 expression were strongly associated with areas of severe epithelial damage in IBD. Keratin expression was most pronounced in patients who had undergone colectomy due to treatment-resistant IBD. DiscussionKeratin changes in IBD and MC but not in IBS highlight their importance in maintaining barrier homeostasis. Whether these changes are causes or consequences for these diseases will warrant further research.

cell biology↗

bioRxiv2025

Effects of incrementally increased plant-based protein intake on gut microbiota and inflammatory-metabolic biomarkers in healthy adults

Shifting to a plant-based diet naturally alters protein source choices. In many countries, protein from yellow pea is widely used as 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/kg body mass/day in week 5 to 1.00 g/kg body mass/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 also 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 bacteria strains and differentially influences markers related to gut inflammation in healthy individuals.

biochemistry↗

bioRxiv2024

Production of bioactive structural motifs from wheat arabinoxylan via colonic fermentation and enzymatic catalysis: evidence of interaction with toll-like receptors from in vitro, in silico and functional analysis

It is well known that dietary fibers (DF) from plant-source foods can induce beneficial health effects through their physicochemical properties and utilization by the gut microbiota during fermentation, which is mainly explored with a focus on changes in the gut microbiota profile and the production of microbial-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. Firstly, a source of wheat arabinoxylan (WAX) was subjected to in vitro simulation of human colonic fermentation, followed by characterization and quantification of WAX structural motifs to explore their dynamics throughout fermentation. The identified structural motifs were further produced through enzymatic catalysis of WAX using carbohydrate-active enzymes and fractionated into six well-defined fractions of arabinoxylans and linear xylans. These fractions of structural motifs were then tested for interaction with TLR2 and TLR4 using a reporter cell assay. Results revealed structure-dependent effects, primarily with inhibition of TLR2 and activation of TLR4 depending on the degree of polymerization and branching of WAX structural motifs. The role of the fine structure of WAX structural motifs was confirmed by molecular docking, which revealed that minor structural changes substantially influence the interaction between structural motifs and TLRs. The results from in vitro and in silico studies also support the hypothesis that the direct effects of oligomers and polysaccharides on cell receptors are likely the result of complex interactions involving multiple cell surface receptors. Finally, in addition to highlighting that direct effects of structural motifs might play an important role in the overall effects of DF, this work suggests that enzymatic-tailoring design of DF can be a potential tool for producing functional ingredients with specific effects on human health.

biochemistry↗