Is there an increased risk of hiv infection/other stis for men & women with celiac disease; both those who are penetrated in anal sex, and those not?

Not really: There is a range of effects with celiac disease.Those who don't know can suffer poor health with impaired nutrition,irritable bowel syndrome,etc. Impaired healing & response to any illness might be expected.Once they get it under control by avoiding gluten & any cross reacting factors like food dyes,food allergies, their response to any illness is like anyone else.