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. 2025 May 12;31(5):1392-1403.
doi: 10.1093/ibd/izae306.

Dietary Carrageenan Amplifies the Inflammatory Profile, but not Permeability, of Intestinal Epithelial Cells from Patients With Crohn's Disease

Eva Vissers  1 , Judith Wellens  1   2 , Lorenzo Giorio  1 , Ward Zadora  3 , Bram Verstockt  1   2 , Marc Ferrante  1   2 , Séverine Vermeire  1   2 , Christophe Matthys  4   5 , Kaline Arnauts  1 , João Sabino  1   2
Affiliations

Dietary Carrageenan Amplifies the Inflammatory Profile, but not Permeability, of Intestinal Epithelial Cells from Patients With Crohn's Disease

Eva Vissers et al. Inflamm Bowel Dis. .

Abstract

Background: The consumption of ultra-processed foods has increased significantly worldwide and is associated with the rise in inflammatory bowel diseases. However, any causative factors and their underlying mechanisms are yet to be identified. This study aimed to further elucidate whether different types of the dietary emulsifier carrageenan (CGN) can alter the permeability and inflammatory state of the intestinal epithelium.

Methods: Caco-2/HT29-MTX cocultures (n = 4) were exposed to either κ-, ι-, or λ-CGN (100 µg mL-1) for 24 hours. Organoid-derived monolayers from patients with Crohn's Disease (CD) were exposed to κ-CGN (100 µg mL-1) for 48 hours (n = 10). In both models, an inflamed condition was established by adding a mix of inflammatory stimuli. Changes in permeability were measured by transepithelial electrical resistance (TEER). In the organoid-derived monolayers, cytokines were quantified in the apical and basolateral supernatant and gene expression was analyzed with RT-qPCR.

Results: None of the CGN subtypes altered permeability of non-inflamed or inflamed Caco-2/HT29-MTX cocultures. In organoid-derived monolayers, κ-CGN did not affect TEER, but induced alterations in the gene expression of tight junctions and mucus proteins. Expression of TNF, IL8, and IL1B increased upon κ-CGN stimulation, both in inflamed and non-inflamed monolayers. Cytokine release in the supernatant was increased by κ-CGN for IL-6, IL-13, IL-4, IL-2, and IL-10.

Conclusions: Dietary CGN caused upregulation of inflammatory markers and affected cytokine release of intestinal epithelial cells from CD patients, while permeability remained unaltered. When inflammation was already present, this pro-inflammatory effect was more pronounced, suggesting a role for dietary CGN during active CD.

Keywords: emulsifiers; inflammatory bowel diseases; intestinal epithelium; organoids; ultra-processed foods.

Plain language summary

This study revealed that the dietary emulsifier carrageenan has direct pro-inflammatory effects on intestinal epithelial cells from patients with Crohn’s disease, without affecting permeability. In an inflamed setting, this was more pronounced, suggesting a role for dietary carrageenan during active inflammation.

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Conflict of interest statement

B.V. receives research support from AbbVie, Biora Therapeutics, Landos, Pfizer, Sossei Heptares and Takeda; receives speaker’s fees from Abbvie, Biogen, Bristol Myers Squibb, Celltrion, Chiesi, Falk, Ferring, Galapagos, Janssen, Lily, MSD, Pfizer, R-Biopharm, Sandoz, Takeda, Tillots Pharma, Truvion and Viatris; receives consultancy fees from Abbvie, Alfasigma, Alimentiv, Applied Strategic, Astrazeneca, Atheneum, BenevolentAI, Biora Therapeutics, Boxer Capital, Bristol Myers Squibb, Galapagos, Guidepont, Landos, Lily, Merck, Mylan, Nxera, Inotrem, Ipsos, Janssen, Pfizer, Progenity, Sandoz, Sanofi, Santa Ana Bio, Sapphire Therapeutics, Sosei Heptares, Takeda, Tillots Pharma, and Viatris; stock options Vagustim. M.F. receives financial support for research from AbbVie, Biogen, EG, Janssen, Pfizer, Takeda, and Viatris; receives speakers’ fees from AbbVie, Biogen, Boehringer Ingelheim, Falk, Ferring, Janssen-Cilag, MSD, Pfizer, Takeda, Truvion Healthcare, and Viatris; and receives consultancy fees from AbbVie, Agomab Therapeutics, Boehringer Ingelheim, Celgene, Celltrion, Eli Lilly, Janssen-Cilag, MRM Health, MSD, Pfizer, Takeda, and Thermo Fisher. S.V. receives financial support for research from AbbVie, J&J, Pfizer, Takeda, and Galapagos; receives speakers’ and consultancy fees from AbbVie, Abivax, AbolerIS Pharma, AgomAb, Alimentiv, Arena Pharmaceuticals, AstraZeneca, BMS, Boehringer Ingelheim, Celgene, Cytoki Pharma, Dr Falk Pharma, Ferring, Galapagos, Genentech-Roche, Gilead, GSK, Hospira, Imidomics, Janssen, J&J, Lilly, Materia Prima, Mestag Therapeutics, MiroBio, Morphic, MrMHealth, Mundipharma, MSD, Pfizer, Prodigest, Progenity, Prometheus, Robarts Clinical Trials, Surrozen, Takeda, Theravance, Tillots Pharma AG, VectivBio, Ventyx, Zealand Pharma. C.M. is chair of the KU Leuven Fund “Nutrition,” a donation-based fund to stimulate research on nutrition. Recipient of travel/accommodation expenses and small participation fee (< 100€/meeting) as a member of working groups of the Belgian Superior Health Council and Belgian Federal Agency of the Safety of the Food Chain. Recipient of travel/accommodation expenses as member of the scientific advisory body of the EU Joint Programme Initiative Healthy Diet, Healthy Life, as co-chair ILSI Europe Task Force Dietary Intake and Exposure, as member ILSI Europe Task Force Nutrient Intake Optimisation. Recipient of honoraria (< 500€/year) as an active member of the advisory board of NutriNews (Belgian Nutrition Information Center). Recipient of honoraria as jury-member of nutrition-related awards and reviewing EU-grants. Recipient of royalties form a textbook (Handboek Voeding, ACCO). Honoraria are used to support research of PhD Students. J.S. receives financial support for research from Galapagos and Viatris; receives speakers’ fees from Abbvie, Falk, Takeda, Pfizer, Galapagos, Ferring, Janssen, and Fresenius; and does consultancy for Janssen, Ferring, Fresenius, Abbvie, Galapagos, Celltrion, Pharmacosmos, and Pharmanovia. All other authors have nothing to disclose.

Figures

Graphical Abstract
Graphical Abstract
Figure 1.
Figure 1.
Overview of the experimental setup. Caco-2/HT29-MTX cocultures were established by seeding 75% Caco-2 cells and 25% HT29-MTX cells on Transwell inserts. After a differentiation period of 20 days, inflammation was induced. On day 21, the apical side of the epithelial cells was stimulated with 100 µg mL-1 of κ-, ι-, or λ-carrageenan (CGN), and the basolateral side was renewed with regular culture medium or the inflammatory mix. Transepithelial electrical resistance (TEER) was measured during the next 24 hours. Organoid-derived monolayers were derived from 5 patients with Crohn’s disease. Organoids were seeded on Transwells and inflammation was induced when a confluent monolayer was formed (day 6). The next day, organoid-derived monolayers were stimulated with 100 µg mL-1 κ-CGN and TEER was measured. After 48 hours, the cells were collected for RNA expression analysis and supernatant was collected for the quantification of cytokines. Figure created with Biorender.com.
Figure 2.
Figure 2.
Carrageenan does not increase the permeability of Caco-2/HT29-MTX cocultures. A and B, Relative transepithelial electrical resistance (TEER) values (compared to t0) over time of non-inflamed (n = 4) (A) and inflamed (n = 4) (B) cell layers, stimulated with 100 µg mL-1 of κ-, ι-, or λ-carrageenan (CGN). C, Relative TEER of non-inflamed cell layers (n = 4) after 2, 4, and 24 hours of CGN stimulation. D, Relative TEER of inflamed cell layers (n = 4) after 2, 4, and 24 hours of CGN stimulation. Kruskal–Wallis test with Dunn’s multiple comparisons test, *P < .05. Abbreviations: CTRL, non-inflamed control; INFL, inflamed control.
Figure 3.
Figure 3.
Kappa-carrageenan (κ-CGN) does not increase the permeability of organoid-derived monolayers from patients with Crohn’s disease. A, Relative transepithelial electrical resistance (TEER) values (compared to t0) over time. Transepithelial electrical resistance decreased significantly after 48 hours + 24 hours pre-stimulation with inflammatory stimuli (P < .001, Paired t-test). B, Stimulation with κ-CGN (100 µg mL-1) for 24 and 48 hours did not affect the relative TEER values of non-inflamed and inflamed epithelial monolayers (n = 10), compared to controls. C + D, κ-CGN induces minor changes in the expression of barrier-related genes. mRNA expression levels of tight junctions (C) and mucus proteins (D) were evaluated with RT-qPCR (n = 8). Expression levels are normalized against 3 housekeeping genes (ACTB, GPADH, RPLP0) and expressed as log2 fold changes, compared to CTRL. Results of repeated-measures one-way ANOVA followed by Šídák’s multiple comparisons test or (°) Friedman tests followed by Dunn’s multiple comparisons test are given (*P < .05, **P < .01, ***P < .001, ****P < .0001, ns, nonsignificant). Abbreviations: CTRL, non-inflamed control; INFL, inflamed control; κ-CGN, kappa-carrageenan.
Figure 4.
Figure 4.
Kappa-carrageenan (κ-CGN) exposure caused upregulation of pro-inflammatory genes in organoid-derived monolayers from patients with Crohn’s disease. mRNA expression levels of inflammation-related genes were evaluated with RT-qPCR (n = 8). Expression levels are normalized against 3 housekeeping genes (ACTB, GPADH, RPLP0) and expressed as log2 fold changes, compared to CTRL. Results of repeated-measures one-way ANOVA followed by Šídák’s multiple comparisons test are given (*P < .05, **P < .01, ***P < .001, ns = non-significant). Abbreviations: CTRL, non-inflamed control; INFL, inflamed control.
Figure 5.
Figure 5.
Kappa-carrageenan (κ-CGN) induces changes in the apical cytokine release of intestinal epithelial cells from Crohn’s disease (CD) patients. The level of pro-inflammatory cytokines was quantified in the apical supernatant after stimulating non-inflamed and inflamed epithelial monolayers from CD patients with κ-CGN for 48 hours (n = 8). Results of repeated-measures one-way ANOVA followed by Šídák’s multiple comparisons test are given (*P < .05, **P < .01, ***P < .001, ****P < .0001, ns = non-significant). Abbreviations: CTRL, non-inflamed control; INFL, inflamed control.
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