However, lysozyme can also be bactericidal for Gram-negative bacteria in vivo through synergistic action with salivary lactoferrin in the normal state.64 Therefore, this in vitro specificity of lysozyme activity may not be largely involved in the dysbiosis of salivary microbiota in IBD patients, in which the abundance of Gram-positive bacteria was not significantly different as compared with HCs (Supplementary Table S3). This evidence concerns the gene LTF and inflammatory bowel disease.