Methods for activating Toll-like receptor 4 via cholesterol-dependent cytolysins isolated from a Gram-positive bacteria are provided. In addition compositions containing an isolated cholesterol-dependent cytolysin or a fragment thereof or a mimetic of the cytolysin or fragment thereof and methods for use of such composition in inhibiting binding and/or interaction of Toll-like receptor 4 with endotoxin are provided. Methods for identifying modulators of Toll-like receptor 4 activation by a cholesterol-dependent cytolysin and use of such modulators in treatment of septicemia and/or septic shock are also provided.