Fig. 5: Whipworm L1 larvae invade caecal epithelium by degrading the overlaying mucus layer.

a MUC2 purified from LS174T cell lysates was incubated with (red squares) or without (black circles) 400 T. muris L1 larvae at 37 °C for 24 h before being subjected to rate zonal centrifugation on linear 6–8 M GuHCl gradients (fraction 1—low GuHCl; fraction 24—high GuHCl). After centrifugation tubes were emptied from the top and the fractions probed with a MUC2 antibody. Data are shown as staining intensity arbitrary units (a.u). Results are represented as the mean +/− standard error of the mean (SEM) of 3 independent experiments. Source data are provided as a Source data file. b Caecaloid mucus degradation by T. muris L1 larvae at 72 h p.i. Transwells were washed with 0.2 M urea in PBS to recover mucus. Washes were subjected to rate zonal centrifugation on linear 5–25% sucrose gradients. After centrifugation tubes were emptied from the top and the fractions were stained with Periodic Acid Shiff’s (PAS) to detect the mucins. Data are shown as percentage of intensity. Black circles represent uninfected caecaloids and red squares represent T. muris L1-infected caecaloids. Results are shown as the mean +/− SEM of 3 replicas of one caecaloid line, which are representative of two caecaloid lines. Source data are provided as a Source data file. c Representative images of toluidine blue-stained transverse sections from caecaloids uninfected and infected with T. muris L1 larvae for 24 h showing degradation (asterisk) of the overlaying mucus layer immediate above the infected cells. Scale bars 20 μm. Imaging experiments on T. muris-infected caecaloids were done in triplicate across at least three independent replicas using three caecaloid lines derived from three C57BL/6 mice. d Measurement of the density of toluidine blue staining via quantification of the %CMYK recorded (Adobe Photoshop). Five data points from each of three areas were counted: (1) mucus layer overlaying uninfected IECs, (2) cleared mucus above IECs infected with whipworm L1 larvae, and (3) mucus-free background (above and away from the IECs section), for each of five L1 larvae infecting caecaloids. Data are presented as median values with interquartile range. ****p < 0.0001 Kruskal Wallis test and Dunn’s comparisons among groups. A Source data file is provided.