Compared to SPF mice, the expression of serine protease inhibitor (Serpina1e) and amyloid P component (APCS), hallmark proteins of colitis, was upregulated more than fourfold in DSS‐treated mice (Figure4A), whereas BP treatment led to a significant downregulation of these two hallmark proteins by more than twofold (p < 0.001; Figure 4A). This evidence concerns the gene SERPINA1 and colitis.