bring something down means make unhappy (e.g. This sad news will bring people down.)
bring up means introduce something in a conversation, or raise, look after a child (e.g. They were brought up by my grandparents. Please don’t bring it up again.)
bring someone up means teach to have beliefs (e.g. My parent brings me up to believe in our own abilities.)
bring something up means to start talking or to vomit (e.g. She was drinking so much I thought she’d bring up her dinner soon.)