LL-37 expression in the rectal mucosa of Intervention or Placebo groups of patients with shigellosis. Rectal biopsies were obtained on day 1 and day 7 from a subgroup of Shigella-infected patients, treated with butyrate (n = 15) or placebo (n = 11). Immunohistochemical detection of LL-37 was performed in paraffin sections. SE and LP were separately assessed for the quantification of LL-37 staining in each tissue section and the results were given as ACIA (Acquired Computerized Image Analysis) score. Lower and upper boundaries of the boxes and the horizontal bars in between indicate 25th percentile, 75th percentile and group median respectively. Single lines extending from the boxes represent lower and upper quartiles. Each circle above or below the boxes indicates one outlier. Two-way repeated measure ANOVA was performed to determine significant interaction between butyrate and placebo therapy on different days, and when interaction was significant the Holm-Sidak post hoc comparison procedure was used to compare the effects of butyrate therapy on outcome measures. Significance: p≤ 0.05. Expression of LL-37 in SE increased significantly from day 1 to day 7 in the Intervention group compared with the Placebo group (p = 0.04). There was no significant changes over time between groups in the expression of LL-37 in LP (p = 0.14). SE- surface epithelium; LP-lamina propria.