TLR4-dependant immune response, but not hepatitis B virus reactivation, is important in radiation-induced liver disease of liver cancer radiotherapy

Abstract

Toll-like receptor 4 (TLR4) is an important trigger of the immune response against hepatitis B virus (HBV) infection and liver injuries. The roles of HBV reactivation versus TLR4-dependant immune response may be critical factors in preventing radiation-induced liver diseases (RILDs) after liver cancer radiotherapy. This study consists of three phases. In the primary phase, livers of mutant TLR4 (TLR4(-)) mice were irradiated with 30 Gy in either the absence or presence of HBV infection. The latter was done by introduction of plasmid pAAV/HBV 1.2. In the advanced phase, RILDs were compared in normal TLR4 (TLR4(+)) versus TLR4(-) mice. In the validation phase, 28 liver cancer patients who had undergone radiotherapy before hepatectomy were enrolled. Liver biopsies near tumors, irradiated with 35-48 Gy, were used to construct tissue microarrays. HBV reactivation, TLR4 expression, and severity of RILDs were studied in both mouse and human. More HBV reactivation, without significant RILD, was observed in irradiated versus unirradiated TLR4(-) mice. RILD scores of TLR4(+) mice were higher than TLR4(-) mice. In humans, serious RILDs tended to develop in patients with high TLR4 expression, but not in patients with low TLR4 or high HBV surface antigen expression. High TLR4 expression was seen in only 2 of 12 HBV-reactive patients, but in HBV-nonreactive patients, it was seen in 6 of 9 (P < 0.03). In summary, RILDs correlated with high TLR4 expression, but not with HBV reactivation, which is inhibited in liver with high TLR4 expression after liver cancer radiotherapy.

TLR4-Dependent Immune Response Promotes Radiation-Induced Liver Disease by Changing the Liver Tissue Interstitial Microenvironment during Liver Cancer Radiotherapy

“…Distress or injury in liver tissues after irradiation might stimulate TLR4, promoting further damage of hepatocytes and hepatic NPCs. The results of our current and previous studies demonstrate that the TLR4-dependent immune response plays a vital role in RILD (13). In the current study, compared with TLR4- showed that TLR4 þ mice developed more severe RILD (moderate granulocyte infiltration and/or piecemeal necrosis in livers indicated by arrows) than TLR4 À mice after 30 Gy irradiation of the liver.…”

“…Mice in the control groups were anesthetized without irradiation. These experiments to induce RILD in mice using helical tomotherapy were performed three times, and the whole liver irradiation procedures were similar to those described in our previous study (13).…”

Activation of the JNK-c-Jun pathway in response to irradiation facilitates Fas ligand secretion in hepatoma cells and increases hepatocyte injury

“…Two independent cohorts with a total of 50 HCC patients were enrolled in this study as previously described [ 15 ]. In one cohort, after about 2 months of liver radiotherapy, 22 liver cancer patients underwent hepatectomy between January 2005 and May 2013.…”

“…Immunohistochemical staining was performed based on the method of Wu [ 15 ]. In a typical procedure, after rehydration and antigen retrieval, cell slides were incubated with diluted primary antibodies against FasL (1:100, Santa Cruz) at 4 °C overnight, followed by HRP-conjugated secondary antibody (anti-rabbit, 1:200; DingguoBio) at 37 °C for 30 min.…”

A mouse radiation‐induced liver disease model for stereotactic body radiation therapy validated in patients with hepatocellular carcinoma

“…In addition, these parameters of the liver RT dose and normal tissue dose constraints of the mouse RILD model in this study were confirmed by another study from our group, which had successfully investigated the mechanism of RILDs related to the TLR4-dependent immune response. 33…”