The effect of aging on the microbiome, the mechanism of action by which the microbiome modulates the immune response, the mechanism by which the relative neutrophil deficiency in the aged host leads to worse outcome, the role of IL-22 in the aging effect on CDI, the interaction of the microbiome and the humoral response, are some of the burning questions raised by these studies. Here, IL22 is linked to hyperinsulinemic hypoglycemia, familial, 4.