TLR4 and colitis: TLR4-mediated production of hyaluronic acid may also induce macrophage Cox-2 and thus exert antiinflammatory effects during DSS colitis.107 Mesenchyme-derived PGE2 preserves proliferation of crypt progenitor cells via MyD88, which is essential for IEC restitution during acute DSS injury.108 Of note, it was recently proposed that DSS may act as a direct alarmin for TLR4,107 but whether DSS truly binds to TLR4 remains to be determined.