Expression of receptor activator of nuclear factor-kappa B ligand in leukocytes during acute kidney rejection after transplantation in rats

The Diagnostic Impact of C4d, CD68, and NF-κB Expression in the Differentiation Between Recurrent Hepatitis C and Acute Cellular Rejection After Liver Transplantation

Liver transplantation is the selected treatment for patients with advanced liver disease and cirrhosis, mostly as a complication of hepatitis C virus (HCV). Recurrent HCV and acute cellular rejection (ACR) of the graft are the most common causes of graft failure. The distinction between the 2 conditions is essential because they are managed differently. In some cases, the clinical and histopathologic features may overlap between recurrent hepatitis C and ACR, making differentiation difficult. The aim of this study was to investigate the role of C4d, CD68, and nuclear factor kappa-B (NF-κB) in the differentiation between ACR and recurrent HCV in the post-liver-transplant biopsy using immunohistochemistry. C4d expression in endothelial cells of portal or central veins (P=0.001) and the number of macrophages highlighted by CD68 (P=0.02) were in favor of ACR, whereas NF-κB expression by hepatocytes was in favor of recurrent hepatitis C. Vascular injury demonstrated by endothelial expression of C4d and prominent macrophage infiltration identified by CD68 expression were the distinguishing criteria for ACR and representing humoral and cellular-mediated immunity as evoking factors for graft injury. The upregulation of NF-κB in the hepatocytes of recurrent hepatitis C could be an immune response to infection or it may be induced by HCV itself.

Quantitation of the Rank-Rankl Axis in Primary Biliary Cholangitis

There is substantial data that suggests an abnormality of innate immunity in patients with primary biliary cholangitis (PBC) which includes the transcription factor nuclear factor-kB (NF-kB) and well as downstream inflammatory signaling pathways. In addition, ImmunoChip analysis has identified a novel PBC-associated locus near the receptor activator of NF-kB ligand (RANKL) gene. Based on these observations, we investigated the role of the RANKL axis in the liver of patients with PBC compared to controls. We used immunohistochemistry to quantitate liver expression of RANKL, its receptor (RANK), and importantly the decoy receptor osteoprotegerin (OPG), including a total of 122 liver samples (PBC = 37, primary sclerosing cholangitis = 20, autoimmune hepatitis = 26, chronic hepatitis B = 32 and unaffected controls = 7). In addition, we studied RANKL-RANK-OPG co-localization in CD4 and CD8 T cells, B cells, dendritic cells, macrophages, NK, NKT cells, hepatocytes, and cholangiocytes. We report herein that RANK is constitutively expressed by cholangiocytes in both unaffected and diseased liver. However, cholangiocytes from PBC express significantly higher levers of RANK than either the unaffected controls or liver diseased controls. CD4, CD8 and CD19 cells with in the portal areas around bile ducts in PBC express significantly higher levels of RANKL compared to controls. Importantly, the overall hepatic RANKL level and the ratio of hepatic RANKL/OPG correlated with disease severity in PBC. In conclusion, our data indicate a role of RANK-RANKL axis in the innate immune activation in PBC and we hypothesize that the damaged cholangiocytes, which express high levels of RANK, lead to the recruitment of RANKL positive cells and ultimately the classic portal tract infiltrates.