The role of immunoglobulin A

Using a systems biology approach, we discovered and dissected a three-way interaction between the immune system, the intestinal epithelium, and the microbiota. We found that mice lacking B lymphocytes, or lacking IgA, have low intestinal expression of lipid metabolism genes regulated by the transcription factor GATA4, and a consequent decrease in fat absorption in the intestine. The defect disappeared in germ free mice, suggesting that it is dependent on the microbiota; and sequencing analysis of the bacteria showed subtle differences between normal and B-cell deficient mice. Analysis of gene expression of gut biopsies from patients with common variable immunodeficiency and intestinal dysfunction revealed a high similarity to mouse B-cell knockout profiles. These data provide an explanation for a longstanding enigmatic association between immunodeficiency and defective lipid absorption in humans. This series represents the subsection of the study where we adress the role of immunoglobulin A. The data is from IgA KO and corresponding control mice. Intensity of each channel was extracted from two-color arrays. We used direct dye swap design and performed paired analysis between small intestine of KO and control mice. Corresponding paires of KO and control were hybridized on the same array and can be matched by the array name.