Defensive linemen Derrick Shelby and Cameron Wake are both questionable for the game, Shelby's injury however is a bit odd in that it isn't a typical football injury you read about. The backup DE was seen in the locker room after the Redskins game with a severe black eye, and it appears to have messed with him substantially.
Wake is the biggest name for the defensive line on this list though, as his pass-rushing prowess will not be easy to replace. If push comes to shove, linebacker Chris McCain has recently said that all of his snaps in practice have been at defensive end, so he would probably be the emergency player there.