Background Non-alcoholic fatty liver disease (NAFLD) roughly affects a quarter of the world
population and is mainly characterized histologically by lipid deposition in hepatocytes.
In some cases, NAFLD may evolve to non-alcoholic steatohepatitis (NASH) with immune
cell recruitment and hepatocyte ballooning. Primary sclerosing cholangitis (PSC) is
a progressive cholangiopathy with onion-skinning fibrosis around injured bile ducts
and inflammatory infiltrates. The goal of this study is to apply a novel multiplex
immunostaining approach optimized in our laboratory, for comparing morphological changes
in liver histology of NAFLD, NASH and PSC patients, and identifying similarities and
discrepancies between immune cell populations.
Methods Liver FFPE sections from normal, NAFLD, NASH and PSC patients, and from mouse NASH
and PSC models were used. We recently implemented in our laboratory a method of sequential
immunostaining that allows to stain >15 markers on a singular FFPE tissue section.
This protocol was combined with digital image analysis tools.
Results We successfully stained and analyzed archival FFPE samples from normal, NAFLD, NASH
and PSC patients. In NASH and PSC, disease stage is associated with remarkable loss
of lobular areas, increased fibrosis and defined infiltration of myeloid and lymphoid
cell populations. NASH patients predominantly exhibit myeloid-cell infiltration, whereas
PSC patients had a pronounced lymphoid cell response. Nonetheless, both diseases displayed
intense monocyte accumulation in the perilobular areas, and this finding was confirmed
on murine models of liver disease.
Conclusions Monocytes/macrophages infiltration and accumulation represent the most common histological
feature associated with the progression of NASH and PSC.
