By Melissa Harris | Dennis Culloton, the public relations man who counseled the Ricketts family through its acquisition of the Chicago Cubs last year, is leaving Guy Chipparoni’s Res Publica Group and striking out on his own.

Culloton said that he is taking the Ricketts account with him but declined to reveal other clients.

“It’s probably premature to reveal that in the Tribune, but I expect to have a strong practice in health care, sports and transportation,” he said.

Those areas match his background. Prior to serving as executive vice president of Res Publica, Culloton worked as press secretary for Illinois Gov. George Ryan and the chief spokesman for the city department overseeing O’Hare and Midway airports. He also was a public affairs executive at Blue Cross and Blue Shield of Illinois.

Lissa Druss Christman, an Emmy-winning executive producer at Comcast SportsNet, will become chief creative officer at Culloton Strategies. Christman said she reconnected with Culloton while producing a half-hour show on the Ricketts family.

Culloton, 44, said his departure from Res Publica and Chipparoni, known as “Chip,” was amicable.

“Chip and I worked together for seven years and have known each other longer than that,” he said. “We talked about this issue for a long time, and I just decided no guts, no glory.”

Chipparoni was not immediately available for comment. Culloton says he’s looking for office space for his new firm today.