Role of interleukin 6 in liver cell regeneration after hemi-hepatectomy, correlation with liver enzymes and flow cytometric study

Preoperative albumin-bilirubin score and liver resection percentage determine postoperative liver regeneration after partial hepatectomy

BACKGROUND

The success of liver resection relies on the ability of the remnant liver to regenerate. Most of the knowledge regarding the pathophysiological basis of liver regeneration comes from rodent studies, and data on humans are scarce. Additionally, there is limited knowledge about the preoperative factors that influence postoperative regeneration.

AIM

To quantify postoperative remnant liver volume by the latest volumetric software and investigate perioperative factors that affect posthepatectomy liver regeneration.

METHODS

A total of 268 patients who received partial hepatectomy were enrolled. Patients were grouped into right hepatectomy/trisegmentectomy (RH/Tri), left hepatectomy (LH), segmentectomy (Seg), and subsegmentectomy/nonanatomical hepatectomy (Sub/Non) groups. The regeneration index (RI) and late regeneration rate were defined as (postoperative liver volume)/[total functional liver volume (TFLV)] × 100 and (RI at 6-months - RI at 3-months)/RI at 6-months, respectively. The lower 25th percentile of RI and the higher 25th percentile of late regeneration rate in each group were defined as "low regeneration" and "delayed regeneration". "Restoration to the original size" was defined as regeneration of the liver volume by more than 90% of the TFLV at 12 months postsurgery.

RESULTS

The numbers of patients in the RH/Tri, LH, Seg, and Sub/Non groups were 41, 53, 99 and 75, respectively. The RI plateaued at 3 months in the LH, Seg, and Sub/Non groups, whereas the RI increased until 12 months in the RH/Tri group. According to our multivariate analysis, the preoperative albumin-bilirubin (ALBI) score was an independent factor for low regeneration at 3 months [odds ratio (OR) 95%CI = 2.80 (1.17-6.69), P = 0.02; per 1.0 up] and 12 months [OR = 2.27 (1.01-5.09), P = 0.04; per 1.0 up]. Multivariate analysis revealed that only liver resection percentage [OR = 1.03 (1.00-1.05), P = 0.04] was associated with delayed regeneration. Furthermore, multivariate analysis demonstrated that the preoperative ALBI score [OR = 2.63 (1.00-1.05), P = 0.02; per 1.0 up] and liver resection percentage [OR = 1.02 (1.00-1.05), P = 0.04; per 1.0 up] were found to be independent risk factors associated with volume restoration failure.

CONCLUSION

Liver regeneration posthepatectomy was determined by the resection percentage and preoperative ALBI score. This knowledge helps surgeons decide the timing and type of rehepatectomy for recurrent cases.

Signaling pathways of liver regeneration: Biological mechanisms and implications

The liver possesses a unique regenerative ability to restore its original mass, in this regard, partial hepatectomy (PHx) and partial liver transplantation (PLTx) can be executed smoothly and safely, which has important implications for the treatment of liver disease. Liver regeneration (LR) can be the very complicated procedure that involves multiple cytokines and transcription factors that interact with each other to activate different signaling pathways. Activation of these pathways can drive the LR process, which can be divided into three stages, namely, the initiation, progression, and termination stages. Therefore, it is important to investigate the pathways involved in LR to elucidate the mechanism of LR. This study reviews the latest research on the key signaling pathways in the different stages of LR.

Induction of synthesis of matrix metalloproteinases by interleukin-6; evidence for hepatic regeneration following hemi-hepatectomy

Aim of the study

Interleukin-6 (IL-6) can play a role in hepatic regeneration through many mechanisms, one of which is the induction of synthesis of matrix metalloproteinases (MMPs). The aim of the study is to focus on the significance and role of MMPs in the regenerative process to reveal the correlation between IL-6 and MMPs in rats following partial hepatectomy.

Material and methods

Following hemi-hepatectomy, eighty male rats were divided into a control group and a group treated with IL-6 35 µg/100 gm body weight according to a lethality study. The blood samples were drawn from all animal groups for MMP-9 serum level assessment. For the quantitative determination of MMP-9 an enzyme-linked immunosorbent assay (ELISA) was used (Cytoimmune Science Inc., MD) through the quantitative sandwich immunosorbent assay technique. A monoclonal antibody for MMP-9 was pre-coated onto microplate standards. After washing away the unbound substances, an enzyme-linked polyclonal antibody specific for cytokine was added to the wells and color developed in proportion to the amount of total cytokine (pro and/or active) bound in the initial step. The color development was stopped and the intensity of the color was measured.

Results

The liver regeneration rate (%) was significantly higher in the group of rats treated with IL-6 (median value was 49.55% vs. 33.20%), p < 0.001. The MMPs’ serum level was significantly higher in the group of rats with resection and treatment (median value was 8.01).

Conclusions

These results give evidence for the vital role of MMPs in the process of hepatic regeneration, the level of which, in turn, has a close relationship with the level of IL-6. MMPs have diverse effects in promoting angiogenesis, remodeling of extracellular matrix and endothelial cell proliferation.