UPDATE 2-Johnson Matthey battles lower profit at its biggest unit

Johnson Matthey on Wednesday lowered the profit outlook for its largest unit that makes pollution filters for cars and trucks and announced the departure of the unit's head, sending its shares down more than 3%. Shares of the FTSE 100 company was the biggest loser on London's blue-chip index. The moves follow scrutiny of Johnson Matthey's catalytic filters for trucks, which have been linked to emission issues at truckmakers Volvo and Cummins.