"the inflammatory response is sparked by antigen derived from gut bacteria, the trillions of gut bacteria"
No, this theory has been debunked countless times.
If the inflammatory response was directed at the gut flora, crohn's disease patients would have superficial inflammation all over the intestine, including the colon, everywhere the gut flora comes into contact with the epithelial cells, there should be inflammation. That is not the case in crohn's disease, crohn's disease involves patchy and deep tissue inflammation.
Only deep transmural inflammation in crohn's disease can lead to fistula and strictures in patients. The response is targeting pathogenic bacteria that have entered tissue.
Granuloma seen in crohn's disease should be enough by themselves to discredit the microbiome theory, granuloma in intestinal disease happens in response to tissue and macrophage penetration of bacteria, it happens in diseases like intestinal TB, it happens during foodborne infections, it happens in every disease that involves a response to a tissue bacteria. Including crohn's disease.
Crohn's disease early endoscopic signs involve inflamed ulcers where M cells reside, which point to specific macrophage penetrating bacteria that have entered tissue and set off macrophages in the lamina propria.
Genetic predispotion in crohn's disease point to an incompetent bacterial recognition in NOD2, and an incompetent xenophagy response in ATG16L1, which again point to intracellular bacteria exploiting phagocytosis incompetence.
Early crohn's disease does not involve dysbiosis, dysbiosis comes later in response to inflammation. Dysbiosis resolves itself when crohn's disease patients take anti-inflammatories. The suggestion that crohn's disease patients came down with the disease because one day, the immune system suddenly decided to lose tolerance to the microbiome and mount an immune response for no reason is a popostrous suggestion.
If the immune response was directed at the dysbiotic microbiome in crohn's disease, fecal transplants would work, they don't.
"diets / vitamins / bile acids"
Crohn's disease will not be solved with diets and vitamins. The inflammation does not start at the epithelial border, it starts in the lamina propria where macrophages are chronically activated, failed clearance of bacteria by phagocyte leads to chronic inflammation. Vitamins or special diets won't change that.
Only elemental nutrition leads to remission, which is a consequence of nutrient deprivation due to high bioavailability and uptake, it has nothing to do with any local effect in the intestine, every single EN works just as well. It's also something no diet will ever be able to replicate. EN are specifically engineered to be bioavailable and to have uptake high in the GI tract.
IV feeds as a dietary intervention work also, by the same mechanic EN do, nutrient deprivation, it lowers bacterial load. Intravenous feed solutions are made by the same companies making EN.
The way EN and IV feeds work is thanks to advances of the last decades that allow us to manipulate nutrients, no diet can recreate this.
After decades of research, there are no known "dietary triggers" in crohn's disease. It does a disservice to crohn's disease patients to put forward the idea that there are, because patients get the dangerous idea in their head that they can manage their own disease if they go on "SCD" or "Paleo", or if they don't eat this or that. The idea that they can manage their own disease without seeking help. If there was a dietary trigger in crohn's disease, we would have found it by now.