Celiac disease, aka sprue, is caused by a malabsorption of nutrients from food in the digestive tract. When individuals affected by this chronic illness intake any food with gluten, the immune system starts attack the small intestines with mediators. Hence, the small intestine's role is impeded from absorbing nutrients from food and the individual has increase risk of weight loss, diarrhea, flatulence, weakness, and abdominal pain.
Removing gluten from the diet stops the small intestine from being destroyed.
As far as the elevated enzymes, the liver gets injured by chemical mediators produced by the immune system to metabolize the byproducts of the food.