Advancements in the pathogenesis of hepatic osteodystrophy and the potential therapeutic of mesenchymal stromal cells.

Hepatic osteodystrophy (HOD) is a metabolically associated bone disease mainly manifested as osteoporosis with the characteristic of bone loss induced by chronic liver disease (CLD). Due to its high incidence in CLD patients and increased risk of fracture, the research on HOD has received considerable interest. The specific pathogenesis of HOD has not been fully revealed. While it is widely believed that disturbance of hormone level, abnormal secretion of cytokines and damage of intestinal barrier caused by CLD might jointly affect the bone metabolic balance of bone formation and bone absorption. At present, the treatment of HOD is mainly to alleviate the bone loss by drug treatment, but the efficacy and safety are not satisfactory. Mesenchymal stromal cells (MSCs) are cells with multidirectional differentiation potential, cell transplantation therapy based on MSCs is an emerging therapeutic approach. This review mainly summarized the pathogenesis and treatment of HOD, reviewed the research progress of MSCs therapy and the combination of MSCs and scaffolds in the application of osteoporotic bone defects, and discussed the potential and limitations of MSCs therapy, providing theoretical basis for subsequent studies.

FOXO1 regulates Th17 cell-mediated hepatocellular carcinoma recurrence after hepatic ischemia-reperfusion injury.

BACKGROUND: Hepatic ischemia-reperfusion injury (IRI) is considered as an effecting factor for hepatocellular carcinoma (HCC) recurrence. Th17/Treg cells are a pair of essential components in adaptive immune response in liver IRI, and forkhead box O1 (FOXO1) has the properties of maintaining the function and phenotype of immune cells. Herein, we illuminated the correlation and function between Th17/Treg cell balance and FOXO1 in IRI-induced HCC recurrence. METHODS: RNA sequencing was performed on naive CD4+ T cells from normal and IRI model mice to identify relevant transcription factors. Western blotting, qRT-PCR, immunohistochemical staining, and flow cytometry were performed in IRI models to indicate the effect of FOXO1 on the polarization of Th17/Treg cells. Then, transwell assay of HCC cell migration and invasion, clone formation, wound healing assay, and Th17 cells adoptively transfer was utilized to assess the function of Th17 cells in IRI-induced HCC recurrence in vitro and in vivo. RESULTS: Owning to the application of RNA sequencing, FOXO1 was screened and assumed to perform a significant function in hepatic IRI. The IRI model demonstrated that up-regulation of FOXO1 alleviated IR stress by attenuating inflammatory stress, maintaining microenvironment homeostasis, and reducing the polarization of Th17 cells. Mechanistically, Th17 cells accelerated IRI-induced HCC recurrence by shaping the hepatic pre-metastasis microenvironment, activating the EMT program, promoting cancer stemness and angiogenesis, while the upregulation of FOXO1 can stabilize the liver microenvironment homeostasis and alleviate the negative effects of Th17 cells. Moreover, the adoptive transfer of Th17 cells in vivo revealed its inducing function in IRI-induced HCC recurrence. CONCLUSIONS: These results indicated that FOXO1-Th17/Treg axis exerts a crucial role in IRI-mediated immunologic derangement and HCC recurrence, which could be a promising target for reducing the HCC recurrence after hepatectomy. Liver IRI affects the balance of Th17/Treg cells by inhibiting the expression of FOXO1, and the increase of Th17 cells has the ability to induce HCC recurrence through EMT program, cancer stemness pathway, the formation of premetastatic microenvironment and angiogenesis.

Aberrant acetylated modification of FGF21­KLB signaling contributes to hepatocellular carcinoma metastasis through the ß­catenin pathway.

ß­Klotho (KLB) is a vital element of the fibroblast growth factor (FGF) receptor complex and acts as a co­receptor to facilitate the binding of FGF19 and FGF21 to the FGFRs on the target cells. The present study aimed to determine the contribution of FGF21­KLB signaling to hepatocellular carcinoma (HCC) metastasis. KLB expression was measured in HCC tissues and cell lines using western blot and reverse transcription­quantitative PCR. Furthermore, the proliferation, apoptosis and metastasis capacity of KLB­knockdown Huh7 cells (human HCC cell line) were assessed by Cell Counting Kit­8 assay, 5­ethynyl­2'­deoxyuridine assay, flow cytometry, wound­healing assay and Transwell assay. Enrichment analysis was used to explore the underlying regulatory mechanisms of KLB. The metastasis potential of human HCC cells in the context of FGF21 with or without KLB inhibition was determined in vitro and in vivo. Acetylated modification of KLB was determined using a co­immunoprecipitation assay. The results indicated a significant upregulation of KLB in HCC tissues compared with the corresponding normal tissues. In addition, KLB expression was closely associated with HCC metastasis. Migration and invasion assays revealed that KLB knockdown promoted the metastatic capability of HCC cells. Gene set variation analysis and subsequent mechanistic investigations revealed that KLB is the upstream regulatory factor of ß­catenin signaling. Furthermore, FGF21 was indicated to suppress HCC metastasis by inhibiting ß­catenin signaling­driven epithelial­mesenchymal transition (EMT), while KLB knockdown and simultaneous FGF21 overexpression promoted HCC cell motility. Histone deacetylase 3 (HDAC3) was further characterized as the potential deacetylase for KLB. Furthermore, the results revealed that HDAC3 inhibitor­mediated acetylated modification led to KLB inactivation, resulting in the blockade of FGF21­KLB signaling, which further triggered the expression of EMT induction­related genes in Huh7 cells. In conclusion, the present study demonstrated that aberrant acetylated modification of KLB inhibited FGF21­KLB signaling, thereby promoting ß­catenin signaling­driven EMT and HCC metastasis.

Mitochondria-Associated Endoplasmic Reticulum Membrane (MAM) Is a Promising Signature to Predict Prognosis and Therapies for Hepatocellular Carcinoma (HCC).

BACKGROUND: The roles of mitochondria and the endoplasmic reticulum (ER) in the progression of hepatocellular carcinoma (HCC) are well established. However, a special domain that regulates the close contact between the ER and mitochondria, known as the mitochondria-associated endoplasmic reticulum membrane (MAM), has not yet been investigated in detail in HCC. METHODS: The TCGA-LIHC dataset was only used as a training set. In addition, the ICGC and several GEO datasets were used for validation. Consensus clustering was applied to test the prognostic value of the MAM-associated genes. Then, the MAM score was constructed using the lasso algorithm. In addition, uncertainty of clustering in single-cell RNA-seq data using a gene co-expression network (AUCell) was used for the detection of the MAM scores in various cell types. Then, CellChat analysis was applied for comparing the interaction strength between the different MAM score groups. Further, the tumor microenvironment score (TME score) was calculated to compare the prognostic values, the correlation with the other HCC subtypes, tumor immune infiltration landscape, genomic mutations, and copy number variations (CNV) of different subgroups. Finally, the response to immune therapy and sensitivity to chemotherapy were also determined. RESULTS: First, it was observed that the MAM-associated genes could differentiate the survival rates of HCC. Then, the MAM score was constructed and validated using the TCGA and ICGC datasets, respectively. The AUCell analysis indicated that the MAM score was higher in the malignant cells. In addition, enrichment analysis demonstrated that malignant cells with a high MAM score were positively correlated with energy metabolism pathways. Furthermore, the CellChat analysis indicated that the interaction strength was reinforced between the high-MAM-score malignant cells and T cells. Finally, the TME score was constructed, which demonstrated that the HCC patients with high MAM scores/low TME scores tend to have a worse prognosis and high frequency of genomic mutations, while those with low MAM scores/high TME scores were more likely to have a better response to immune therapy. CONCLUSIONS: MAM score is a promising index for determining the need for chemotherapy, which reflects the energy metabolic pathways. A combination of the MAM score and TME score could be a better indicator to predict prognosis and response to immune therapy.

FOXO1 Alleviates Liver Ischemia-reperfusion Injury by Regulating the Th17/Treg Ratio through the AKT/Stat3/FOXO1 Pathway.

Background and Aims: Hepatic ischemic reperfusion injury (IRI) occurring during surgery seriously affects patient prognosis. The specific mechanism of IRI has not been fully elucidated. The study aim was to explore the changes of inflammatory environment, and the relationship of the Th17/Treg cell ratio and FOXO1 expression in hepatic IRI. Methods: Liver samples at different ischemic times were collected from patients and mice. The expression of inflammatory markers and FOXO1 in the liver was detected by western blotting and qPCR. Phenotypic changes of liver lymphocytes were analyzed by flow cytometry. The AKT/Stat3/FOXO1 pathway was verified by targeting AKT with GSK2141795. The role of FOXO1 in liver inflammation and changes in lymphocyte phenotype was confirmed by upregulating FOXO1 with resveratrol. Results: Prolonged ischemic time aggravates liver injury in both humans and mouse models of hepatic IRI. IR-stress caused Th17/Treg imbalance and FOXO1 down-regulation by activating the AKT/Stat3/FOXO1 signaling pathway. Upregulation of FOXO1 reversed the Th17/Treg cytokine imbalance and altered the inflammation environment in the liver. Conclusions: Liver IRI induced Th17/Treg imbalance. Upregulation of FOXO1 reversed the imbalance and alleviated liver inflammation.

Transplantation of Mesenchymal Stem Cells Attenuates Acute Liver Failure in Mice via an Interleukin-4-dependent Switch to the M2 Macrophage Anti-inflammatory Phenotype.

Background and Aims: Transplantation of mesenchymal stem cells (MSCs) derived from bone marrow (BM) is an alternative treatment of acute liver failure (ALF) mainly because of the resulting anti-inflammatory activity. It is not known how MSCs regulate local immune responses and liver regeneration. This study explored the effects of MSCs on hepatic macrophages and the Wnt signaling pathway in ALF. Methods: MSCs were isolated from BM aspirates of C57BL/6J mice, and transplanted in mice with ALF induced by D-galactosamine (D-Gal). The proliferation of hepatocytes was assayed by immunohistochemical (IHC) staining of Ki-67 and proliferating cell nuclear antigen (PCNA). The levels of key proteins in the Wnt signaling pathway were assayed by western blotting and cytokines were determined enzyme-linked immunosorbent assays (ELISAs). A macrophage polarization assay characterized the M1/M2 ratio. The potential role of interleukin-4 (IL-4) in the biological activity of MSCs was determined by silencing of IL-4. Results: Transplantation of allogeneic MSCs significantly attenuated D-Gal-induced hepatic inflammation and promoted liver regeneration. MSC transplantation significantly promoted a phenotypic switch from proinflamatory M1 macrophages to anti-inflammatory M2 macrophages, leading to significant Wnt-3a induction and activation of the Wnt signaling pathway in mice with D-Gal-induced ALF. Of the paracrine factors secreted by MSCs (G-CSF, IL-6, IL-1 beta, IL-4, and IL-17A), IL-4 was specifically induced following transplantation in the ALF model mice. The silencing of IL-4 significantly abrogated the phenotypic switch to M2 macrophages and the protective effects of MSCs in both the ALF model mice and a co-culture model in an IL-4 dependent manner. Conclusions: In vivo and in vitro studies showed that MSCs ameliorated ALF through an IL-4-dependent macrophage switch toward the M2 anti-inflammatory phenotype. The findings may have clinical implications in that overexpression of IL-4 may enhance the therapeutic effects of allogeneic MSC transplantation in the treatment of ALF.

The role and function of CD4+ T cells in hepatic ischemia-reperfusion injury.

INTRODUCTION: Hepatic ischemia-reperfusion injury (IRI) is a severe complication frequently encountered in liver surgery, seriously affecting the therapeutic effects, tissue function. Various immune cells are involved in hepatic IRI, including macrophages, NKT cells, DCs, CD4 + T cells, and CD8 + T cells, among which CD4 + T cells play a critical role in this process. This article aims to summarize the functions and changes in various CD4 + T cell type counts and related cytokine levels in hepatic IRI and to review the possible mechanisms of mutual conversion between T cell types. AREAS COVERED: We have covered the functions and changes that occur in Th1, Th17, and Treg cells in liver IRI, as well as the pathways and factors associated with them. We also discuss the prospects of clinical application and future directions for therapeutic advances. EXPERT OPINION: This section explores the current clinical trials involving CD4 + T cells, especially Tregs, explains the limitations of their application, and summarizes the future development trends of cell engineering and their combination with the CAT technology. We also provide new ideas and therapeutic targets for alleviating liver IRI or other liver inflammatory diseases.