Gene expression in the colon of DSS-treated Pglyrp1-/-, Pglyrp2-/-, Pglyrp3-/-, and Pglyrp4-/- mice

Pglyrp1-/-, Pglyrp2-/-, Pglyrp3-/-, and Pglyrp4-/- mice are all more sensitive than wild type (WT) mice to dextran sulfate sodium (DSS)-induced colitis. The purpose of this study was to determine which genes are differentially induced by DSS treatment in the colon of Pglyrp1-/-, Pglyrp2-/-, Pglyrp3-/-, and Pglyrp4-/- mice compared to WT mice. The results demonstrate higher induction of proinflammatory gene expression in Pglyrp1-/-, Pglyrp2-/-, Pglyrp3-/-, and Pglyrp4-/- mice than in WT mice after DSS treatment. The majority of genes whose expression is increased in Pglyrp1-/-, Pglyrp2-/-, Pglyrp3-/-, and Pglyrp4-/- mice but not in WT mice are interferon-inducible genes. Thus, Peptidoglycan Recognition Proteins Pglyrp1, Pglyrp2, Pglyrp3, and Pglyrp4 protect mice from excessive inflammatory response and damage to the colon by limiting expression of interferon-inducible genes in the colon. WT and Pglyrp1-/-, Pglyrp2-/-, Pglyrp3-/-, and Pglyrp4-/- mice (5/group) were either untreated or treated orally with 5% dextran sulfate sodium (DSS) in drinking water for 48 hrs. RNA was obtained from the colon from each mouse individually and assayed for gene expression using whole genome arrays (Affymetrix Mouse GeneChip® Gene 1.0 ST Array).