In a Dutch oven, cook sausage and ground beef over medium heat until meat is cooked and browned; drain. Stir in onion, celery and garlic. Cook and stir until tender. Add tomatoes, beans, broth, tomato paste, sugar, chili powder, Worcestershire sauce, cumin and red pepper flakes. Bring to a boil; reduce heat, cover and simmer for 20 minutes, stirring occasionally. Serve with cheese, sour cream and onion.