The 12,13-diHOME produced by bacterial epoxide hydrolase genes altered the expression of PPARγ (peroxisome proliferator-activated receptor γ)-regulated genes, reduced anti-inflammatory cytokine secretion and the number of regulatory T cells, increased inflammation, impeded immune tolerance and was involved in the development of atopy, eczema, or asthma (45). This evidence concerns the gene PPARG and asthma.