P0143Dual Effects of Lauric Acid on EMT Regulation in Colonic Epithelial Cells: TLR2 Activation and PPARγ Restraint

Background We previously demonstrated that LA induces epithelial–mesenchymal transition (EMT) in human colonic epithelial (CoEpi) cells, notably increasing SNAI2 (SLUG) expression without affecting SNAI1 (Patel et al., 2025). However, the receptors capable of mediating these LA-driven responses remain unknown. Methods To evaluate whether lauric acid (LA) induces EMT in colonic epithelial cells and to identify the receptors mediating this response, CoEpi cells were stimulated with LA (0–250 µM) under basal or pro-fibrotic conditions (TGFβ1, 10 ng/mL). EMT markers and potential LA-responsive receptors (GPR84, TLR4, TLR2, PPARγ, PPARα, and TRPV1) were screened by PCR. Since LA at 250 µM selectively upregulated TLR2 and GPR84, these receptors were further examined using siRNA silencing (siTLR2, siGPR84). Protein expression of EMT markers was assessed by Western blot. Data, expressed as fold change (mean ± SEM) relative to 0 µM LA, were analyzed using parametric ANOVA or non-parametric Kruskal–Wallis tests as appropriate, and pairwise comparisons were performed using Student’s t-test or Mann–Whitney U test based on normality. (*P < 0.05 vs. 0 µM LA; **P < 0.01 vs. 0 µM LA; #P < 0.05 vs. 0 µM LA + TGFβ1; ##P < 0.01 vs. 0 µM LA + TGFβ1). Results GPR84 and TLR2 mRNA levels were markedly elevated by LA under both basal conditions (250 µM: 6.9 ± 1.5** and 3.3 ± 1.0*, respectively) and pro-fibrotic stimulation (250 µM: 5.1 ± 1.0## and 5.1 ± 0.8##, respectively). In contrast, the antifibrotic receptors PPAR-α and PPAR-γ were only upregulated in the presence of TGFβ1 (2.2 ± 0.3## and 3.4 ± 0.9##, respectively). Although siGPR84 efficiently reduced GPR84 mRNA expression, it neither prevented the EMT-like transcriptional response induced by LA nor modified the elevated levels of PPAR-γ. In sharp contrast, siTLR2 partially reversed the EMT-like phenotype, restoring E-cadherin expression and reducing Vimentin and Snail/Slug mRNA levels. To assess whether these transcriptional changes translated into functional protein alterations, EMT markers were measured by Western blot. No significant differences were observed in E-cadherin or Snail protein levels, and Vimentin abundance was even lower than in controls (250 µM: 0.5 ± 0.1*; 250 µM + TGFβ1: 0.8 ± 0.07#), indicating that the EMT program initiated at the mRNA level does not progress into a complete protein-level transition. Conclusion LA activates a TLR2-dependent inflammatory program that initiates early EMT transcription in colonic epithelial cells without progressing to a full protein-level transition. This suggests that TLR2-mediated inflammatory activation, together with the concurrent induction of PPARγ, may function as a protective mechanism that limits profibrotic progression Reference: Patel J, Cejudo-Garcés A, Jarén A, Macias-Ceja D C, López A, Manresa M, Calatayud S, Barrachina M D, Cosín-Roger J, Ortiz-Masiá D. “P0164 Lauric Acid in Inflammatory Bowel Disease: Balancing Fibrosis Modulation and Epithelial–Mesenchymal Transition Activation.” Journal of Crohn’s and Colitis. 2025;19(Suppl 1):i562. doi:10.1093/ecco-jcc/jjae190.0338. Conflict of interest: Patel, Jalpa: No conflict of interest Cejudo-Garcés, Andrea: Nothing to disclosure Jarén, Ana: Nothing to disclouse Macias-Ceja, Dulce: No conflict of interest Cosín-Roger, Jesús: No conflict of interest Prof. Dr. Ortiz-Masiá, Dolores: No conflict of interest