<qa>  What is the NIHs substudy?Outcome parameters include the rates of complete and partial steroid tapering while maintaining remission, the rates of adverse events, and secondary clinical outcomes such as duration of response, rate of and time to relapse, and changes in symptom index scores. In addition, the NIH will perform a substudy that includes serial colonoscopy to measure cytokine and cell population changes in mononuclear cells extracted from biopsies. 