Systems biologic analysis of T regulatory cells genetic pathways in murine primary biliary cirrhosis

CD4(+)Foxp3(+) regulatory T cells (Tregs) play a non-redundant role in control of excessive immune responses, and defects in Tregs have been shown both in patients and murine models of primary biliary cirrhosis (PBC), a progressive autoimmune biliary disease. Herein, we took advantage of a murine model of PBC, the dominant negative transforming growth factor beta receptor II (dnTGF beta RII) mice, to assess Treg genetic defects and their functional effects in PBC. By using high-resolution microarrays with verification by PCR and protein expression, we found profound and wide-ranging differences between dnTGF beta BRII and normal, wild type Tregs. Critical transcription factors were down-regulated including Eos, Ahr, Klf2, Foxp1 in dnTGF beta RII Tregs. Functionally, driTGF beta RII Tregs expressed an activated, pro-inflammatory phenotype with upregulation of Ccl5, Granzyme B and IFN-gamma. Genetic pathway analysis suggested that the primary effect of loss of TGF beta pathway signaling was to down regulate immune regulatory processes, with a secondary upregulation of inflammatory processes. These findings provide new insights into T regulatory genetic defects; aberrations of the identified genes or genetic pathways should be investigated in human PBC Tregs. This approach which takes advantage of biologic pathway analysis illustrates the ability to identify genes/pathways that are affected both independently and dependent on abnormalities in TGF beta signaling. Such approaches will become increasingly useful in human autoimmunity. (C) 2015 Elsevier Ltd. All rights reserved.