Z Gastroenterol 2015; 53 - K13
DOI: 10.1055/s-0035-1558918

Distinct CD4+ T cell subset composition with higher Th17/Treg ratio in peripheral blood and hepatic tissue of patients with NAFLD, NASH and healthy controls

M Rau 1, A Schilling 1, J Meertens 1, I Hering 1, T Kudlich 1, C Jurowich 2, N Beyersdorf 3, A Geier 1
  • 1Division of Hepatology, Department of Medicine II, University Hospital Würzburg
  • 2Department of General and Visceral Surgery, University Hospital Würzburg
  • 3Institute for Virology and Immunobiology, University of Würzburg

Background: The prevalence of non-alcoholic fatty liver disease (NAFLD) is rising in the last decades and non-alcoholic fatty liver (NAFL) as well as non-alcoholic steatohepatitis (NASH) are now endemic in Western countries. The current hypothesis about the pathogenesis is a two hit theory, i.e. first steatosis due to e.g. metabolic syndrome and then inflammation of the fatty liver due to bacterial translocation from the gut. Thus, 5 to 20% of NAFL patients progress to NASH. It is still not well understood why some patients develop NASH and others remain with NAFL. Higher frequencies of Th17 cells were observed in livers of a NASH mouse model and higher IL-17 and IL-21 gene expression was described in human livers of NASH patients.

We hypothesized that the phenotype of peripheral CD4+ T cells might be predictive for the degree and quality of hepatic T cell infiltration and histopathology.

Aims: To analyse differences in the hepatic and peripheral immune phenotype in patients with NAFL and NAFLD with a focus on conventional CD4+ effector T cell subsets and CD4+ regulatory T cells (Tregs).

Methods: 40 patients with NAFL, 17 patients with NASH and 44 healthy controls (HC) were included in this study. Multi-colour FACS analysis was performed of PBMCs and intrahepatic lymphocytes. CD4+ T cells were stimulated with PMA and ionomycin for intracellular detection of cytokine production (IL-17, IL-4, INF-g, IL-21).

Results: Patients were older, had a higher BMI and a higher CK-18 serum level in comparison to HC. In peripheral blood, NAFLD and NASH patients had higher frequencies of HLA-DR+, i.e. activated, effector memory, IFN-g+, IL-17+, IL-21+ and IL-4+ cells and lower frequencies of CD45RA+ CD25+ resting Tregs among CD4+ T cells than HC. Closer analysis of Th1 cells among PBMCs revealed that T-bet expression was lower among CXCR3+ cells of NASH than NAFLD patients. The CD4+ T cells infiltrating the liver of NAFLD and NASH patients consisted to more than 80% of CXCR3+ effector memory cells with more than 50% recently activated, i.e. HLA-DR+, cells and frequencies of cells producing the named cytokines elevated at least five- to ten-fold in comparison to PBMCs. Higher frequencies of IL-17+ cells among intrahepatic CD4+ T cells and a higher Th17/resting Treg ratio distinguished NAFLD from NASH patients.

Conclusions: Our data indicate that NAFL patients show a “prehepatitic” immune cell profile very similar to that seen in NASH. The progression from NAFLD to NASH is marked by increased frequencies of IL-17+ cells among intrahepatic CD4+ T cells and a higher Th17/Treg ratio. In the peripheral blood, NASH patients showed a lower expression of T-bet among CXCR3+ CD4+ T cells than NAFLD patients.