Question

1. Patients with inflammatory bowel disease (IBD) have been shown to have gastrointestinal (GI) microbes distinct from healthy patients that are matched for age/weight/diet and other variables. One hallmark of IBD is the leakage of IgA from the GI tract into the bloodstream. How would you determine if the GI microbiota of IBD patients can cause IgA leakage (in detail)? Assume that you have access to GI microbiota samples from IBD patients and matched healthy controls, a colony of germ-free mice, and a blood test for IgA. (3 pts)

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Answer 1

In order to determine if the effect of GI microbiota on leakage of IgA into the bloodstream, the following experiment needs to be done

First and foremost, confirm that the germ-free mice do not have any IgA leakage by doing a blood test.

Now, to one half of the germ-free mice colony, marked as 'test',  introduce the gut microbiota of individuals with IBD ( who also shows IgA leakage).

Introduce the gut microbiota of matched healthy individuals ( those without IBD and IgA leakage) into the other half of the mice colony ( control )

Now monitor the blood of these 'test' and çontrol'mice for leakage of IgA into it by using the blood test for IgA.

If the germ-free mice with the 'test' microbiota, i.e one from the individuals who have IBD develop leakage of IgA into the bloodstream while the control population of mice does not show any IgA leakage, it can be shown that the gut microbiota in the affected individuals has a direct effect on the IgA leakage.