Subcutaneous Inoculation of Echinococcus multilocularis Induces Delayed Regeneration after Partial Hepatectomy

Abstract

Alveolar echinococcosis (AE) is caused by the larval stage of echinococcus multilocularis (E. multilocularis), and hepatectomy is the main modality in hepatic AE patients. Liver regeneration after partial hepatectomy (PHx) in such patients is challenging, and further investigation is needed. Thus far, knowledge regarding the possible impact of E. multilocularis on liver regeneration after PHx is limited. Herein, a subcutaneous infection model of E. multilocularis was developed in C57 BL/6 mice, and after 3 months, PHx was performed. Plasma and liver samples were harvested under inhalational isofluorane (2%) anaesthesia at designated post-PHx time points (0, 24, 48, 96 and 168 h). The parameters included the future remnant liver/body weight ratio (FLR/BW), liver function tests (AST and ALT) and related cytokines (TNF-α, IL-6, Factor V, HMGB1, TGF-β, TSP-1, and TLR4) and proteins (MyD88 and STAT3). To assess the proliferation intensity of hepatocytes, BrdU, Ki67 and PAS staining were carried out in regenerated liver tissue. The FLR/BW in the infected group from 48 h after surgery was lower than that in the control group. The BrdU positive hepatocyte proportions reached their peak at 48 h in the control group and 96 h in the infected group and then gradually decreased. During the first 48 h after surgery, both the AST and ALT levels in the infected group were lower; however, these levels were altered from 96 h after surgery. In the infected group, the concentrations and mRNA expression levels of the pre-inflammatory cytokines TNF-α and IL-6 demonstrated a delayed peak. Moreover, post-operatively, the TGF-β and TSP-1 levels showed high levels in the infected group at each different time-point compared to those in the control group; however, high levels of TGF-β were observed at 96 h in the control group. The MyD88 and STAT3 protein expression levels in the infected group were markedly higher than those in the control group 96 h after surgery. Delayed liver regeneration after PHx was observed in the C57 BL/6 mice with the subcutaneous infection of E. multilocularis in the current study. This phenomenon could be partially explained by the alteration in the pro-inflammatory cytokines in the immunotolerant milieu induced by chronic E. multilocularis infection.