I don't know the "technical" reason but my dentist(s) and orthodontist told me my lower jaw is arthritic, and kept growing past the time it should, relative to the fixed upper jaw, so it is pressing outwards on the teeth in the upper jaw, and that is also why I can't open my mouth quite as far as a normal person. I know when my adult teeth came in it was way too crowded in there, and before they tried to fix this with the braces, I had to have both the wisdom teeth and 4 smaller bicuspids removed, then they tried to change the shape of my upper palate first (as an adult). I read somewhere that hormones and growth rate can be effected by lack of nutrition and that affects when different body parts mature, so a lot of people can have teeth crowding, and smaller jaws, I wish I had bookmarked that. Things that are not aligned perfectly tend to get a lot of pressure on them, also, I suspect it can affect saliva production to get glutened, but haven't read any studies on this.
Sinuses, I don't know the technical explanation either, but everyone knows certain foods make them "snottier" than normal. If I want to make my nose run, all I have to do is eat the wrong thing and go outside when it's cooler and exercise. It turns into a multiple kleenex event. When I was younger, I could not figure out why most other people's noses did not do this. I remember taking PE classes outdoors, and always having to use tissues. Now, my nose sort of behaves itself, if I'm eating properly, allowing for there is still a lot of pollen at certain times of year. Perhaps the excess snot produced is more vulnerable to getting infections overall, if there is an ongoing auto immune attack, coinciding with decreased moisture being produced, and changes in temperature. Wonder if being low in certain vitamins or minerals contributes... Infected, trapped snot in sinuses = headache. Mouth? Again, I know I have dry mouth because the dentists tell me this, even tho the not very cognizant rheumies I have seen try to tell me this is "not" sjogrens, to which I think "talk to the dental hand" and get back with me. Also had a nurse explain to me that with my drier than normal mucous membranes, I should never mess around with a chest cold but be seen soon, also, I should try not to take antihistamines for it if I could stand it, as that also would tend to make it worse getting the proper drainage, and they wanted me to cough "productively," and it would be better to get the nose running to get rid of it sooner.
I get much less sick, gluten free, knock on wood.
You could try searching around Pub Med, I found one study from 2002 where the researchers tried putting gliadin directly into the noses of the patients to see what would happen, and there was an inflammatory response from the nasal mucosa. While this isn't exactly what you wanted, because we normally don't snort gluten, but eat it accidentally, it is sort of funny that somebody, somewhere, thought of trying it to see what would happen, since we've had some strong discussions about topical applications of gluten in toiletries and cosmetics in the past on this board. http://www.ncbi.nlm....les/PMC1906320/
If the gut being inflamed can cause snot nose, then we have the answer. And here you go: Chronic sinonasal disease in patients with inflammatory bowel disease:
48% of patients with chronic gut problems have sinus problems, too. Aha!