Hepatic overexpression of cAMP-responsive element modulator α induces a regulatory T-cell response in a murine model of chronic liver disease

Objective Th17 cells are a subset of CD4 + T-helper cells characterised by interleukin 17 (IL-17) production, a cytokine that plays a crucial role in inflammation-associated diseases. The cyclic AMP-responsive element modulator-α (CREMα) is a central mediator of T-cell pathogenesis, which contributes to increased IL-17 expression in patients with autoimmune disorders. Since an increased Th17 response is associated with a poor prognosis in patients with chronic liver injury, we investigated the relevance of Th17 cells for chronic liver disease (CLD) and hepatocarcinogenesis. Design Transgenic mice overexpressing CREMα were crossed with hepatocyte-specific Nemo knockout mice (Nemo Δhepa ) to generate Nemo Δhepa /CREMα Tg mice. The impact of CREMα Tg on CLD progression was examined. Additionally, soft agar colony formation assays, in vitro studies, adoptive transfer of bone marrow-derived cells (BMDCs) and T cells, and gene arrays in T cells were performed. Results 8-week-old Nemo Δhepa /CREMα Tg mice presented significantly decreased transaminase levels, concomitant with reduced numbers of CD11b + dendritic cells and CD8 + T cells. CREMα Tg overexpression in Nemo Δhepa mice was associated with significantly reduced hepatic fibrogenesis and carcinogenesis at 52 weeks. Interestingly, hepatic stellate cell-derived retinoic acid induced a regulatory T-cell (Treg) phenotype in CREMα Tg hepatic T cells. Moreover, simultaneous adoptive transfer of BMDCs and T cells from CREMα Tg into Nemo Δhepa mice ameliorated markers of liver injury and hepatitis. Conclusions Our results demonstrate that overexpression of CREMα in T cells changes the inflammatory milieu, attenuating initiation and progression of CLD. Unexpectedly, our study indicates that CREMα transgenic T cells shift chronic inflammation in Nemo Δhepa livers towards a protective Treg response.