NADPH oxidase 4 (Nox4) deletion accelerates liver regeneration in mice

Liver is a unique organ in displaying a reparative and regenerative response after acute/chronic damage or partial hepatectomy, when all the cell types must proliferate to re-establish the liver mass. The NADPH oxidase NOX4 mediates Transforming Growth Factor-beta (TGF-β) actions, including apoptosis in hepatocytes and activation of stellate cells to myofibroblasts. Aim of this work was to analyze the impact of NOX4 in liver regeneration by using two mouse models where Nox4 was deleted: 1) general deletion of Nox4 (NOX4-/-) and 2) hepatocyte-specific deletion of Nox4 (NOX4hepKO). Liver regeneration was analyzed after 2/3 partial hepatectomy (PH). Results indicated an earlier recovery of the liver-to-body weight ratio in both NOX4-/- and NOX4hepKO mice and an increased survival, when compared to corresponding WT mice. The regenerative hepatocellular fat accumulation and the parenchyma organization recovered faster in NOX4 deleted livers. Hepatocyte proliferation, analyzed by Ki67 and phospho-Histone3 immunohistochemistry, was accelerated and increased in NOX4 deleted mice, coincident with an earlier and increased Myc expression. Primary hepatocytes isolated from NOX4 deleted mice showed higher proliferative capacity and increased expression of Myc and different cyclins in response to serum. Transcriptomic analysis through RNA-seq revealed significant changes after PH in NOX4-/- mice and support a relevant role for Myc in a node of regulation of proliferation-related genes. Interestingly, RNA-seq also revealed changes in the expression of genes related to activation of the TGF-β pathway. In fact, levels of active TGF-β1, phosphorylation of Smads and levels of its target p21 were lower at 24 h in NOX4 deleted mice. Nox4 did not appear to be essential for the termination of liver regeneration in vivo, neither for the in vitro hepatocyte response to TGF-β1 in terms of growth inhibition, which suggest its potential as therapeutic target to improve liver regeneration, without adverse effects.

Bone Geometry, Density, and Microarchitecture in the Distal Radius and Tibia in Adults With Marfan Syndrome Assessed by HR-pQCT

Marfan syndrome (MFS) is a hereditary disorder of connective tissue caused by mutations in the fibrillin-1 gene. Studies have shown that patients with MFS have lower bone mass, but little is known about the other constituents of bone strength. We hypothesize that patients with MFS will have larger bone area and compromised cortical microarchitecture compared with non-MFS individuals. A total of 74 adult patients with MFS and 145 age- and sex-matched non-MFS reference individuals were included in this study. High-resolution peripheral quantitative computed tomography (HR-pQCT) at the distal radius and distal tibia and dual-energy X-ray absorptiometry of total hip and the lumbar spine were performed, and bone turnover and sex hormones were measured. Patients with MFS had significantly lower areal bone mineral density (BMD) at the total spine (-13%) and total hip (-7%) when compared with the reference group. Patients with MFS had significantly larger total bone area at both the radius (+27%) and tibia (+34%). Volumetric BMD at both measured sites showed significantly reduced total, trabecular, and cortical volumetric BMD in patients with MFS compared with the reference group. The microarchitectural parameters at the radius and tibia were compromised in patients with MFS with significantly reduced trabecular number and thickness, leading to a higher trabecular separation and significantly reduced cortical thickness and increased cortical porosity compared with the reference group. The differences in bone density, geometry, or microarchitecture were not explained by increased bone turnover markers or circulating levels of sex hormones. We conclude patients with MFS have altered bone geometry, altered bone microstructure, and lower bone mass (lower areal BMD and volumetric BMD at all sites) compared with healthy reference individuals. Future studies should focus on fracture rates and fracture risk in adult and aging patients with MFS. © 2020 American Society for Bone and Mineral Research (ASBMR).

Cooperative Effect of Erythropoietin and TGF-β Inhibition on Erythroid Development in Human Pluripotent Stem Cells

Patient-specific human induced-pluripotent stem cells (hiPSCs) represent important cell sources to treat patients with acquired blood disorders. To realize the therapeutic potential of hiPSCs, it is crucial to understand signals that direct hiPSC differentiation to a hematopoietic lineage fate. Our previous study demonstrated that CD34(+)CD31(+) cells derived from human pluripotent stem cells (hPSCs) contain hemato-endothelial progenitors (HEPs) that give rise to hematopoietic cells and endothelial cells. Here, we established a serum-free and feeder-free system to induce the differentiation of hPSC-derived CD34(+)CD31(+) progenitor cells to erythroid cells. We show that extracellular matrix (ECM) proteins promote the differentiation of CD34(+)CD31(+) progenitor cells into CD235a(+) erythroid cells through CD41(+)CD235a(+) megakaryocyte-erythroid progenitors (MEP). Erythropoietin (EPO) is a predominant factor for CD34(+)CD31(+) progenitor differentiation to erythroid cells, whereas transforming growth factor beta (TGF-β) inhibits the development of CD34(+)CD31(+) progenitor cells. Apoptosis of progenitor cells is induced by TGF-β in early erythroid differentiation. Suppression of TGF-β signaling by SB431542 at early stage of CD34(+)CD31(+) progenitor differentiation induces the erythroid cell generation. Together, these findings suggest that TGF-β suppression and EPO stimulation promote erythropoiesis of CD34(+)CD31(+) progenitor cells derived from hPSCs.

Interferon-microRNA signalling drives liver precancerous lesion formation and hepatocarcinogenesis

OBJECTIVE

Precancerous lesion, a well-established histopathologically premalignant tissue with the highest risk for tumourigenesis, develops preferentially from activation of DNA damage checkpoint and persistent inflammation. However, little is known about the mechanisms by which precancerous lesions are initiated and their physiological significance.

DESIGN

Laser capture microdissection was used to acquire matched normal liver, precancerous lesion and tumour tissues. miR-484(-/-), Ifnar1(-/-) and Tgfbr2(△hep) mice were employed to determine the critical role of the interferon (IFN)-microRNA pathway in precancerous lesion formation and tumourigenesis. RNA immunoprecipitation (RIP), pull-down and chromatin immunoprecipitation (ChIP) assays were applied to explore the underlying mechanisms.

RESULTS

miR-484 is highly expressed in over 88% liver samples clinically. DEN-induced precancerous lesions and hepatocellular carcinoma were dramatically impaired in miR-484(-/-) mice. Mechanistically, ectopic expression of miR-484 initiates tumourigenesis and cell malignant transformation through synergistic activation of the transforming growth factor-β/Gli and nuclear factor-κB/type I IFN pathways. Specific acetylation of H3K27 is indispensable for basal IFN-induced continuous transcription of miR-484 and cell transformation. Convincingly, formation of precancerous lesions were significantly attenuated in both Tgfbr2(△hep) and Ifnar1(-/-) mice.

CONCLUSIONS

These findings demonstrate a new protumourigenic axis involving type I IFN-microRNA signalling, providing a potential therapeutic strategy to manipulate or reverse liver precancerous lesions and tumourigenesis.

Tim-3 fosters HCC development by enhancing TGF-β-mediated alternative activation of macrophages

OBJECTIVE

Tumour-associated macrophages (TAMs) and their alternative activation contribute greatly to the development of hepatocellular carcinoma (HCC). Tim-3 is highly expressed on macrophages and regulates macrophage functions in several conditions. However, whether Tim-3 is involved in the activation and the function of TAMs has not been reported.

DESIGN

Tim-3 expression in HCC samples was evaluated by flow cytometry, immunohistochemistry and confocal analysis. We analysed the effects of Tim-3 knockdown on macrophages in growth of H22 tumour homografts in BALB/c mice. Tim-3 interference was performed by neutralising antibody, small interfering RNA or short hairpin RNA-expressing lentivirus. Cytokine production was evaluated by reverse transcription PCR, ELISA or Cytometric Bead Array. The effects of Tim-3 interference in macrophages were examined with regard to alternative activation of macrophages and proliferation and migration of Hepa1-6 cells. Cell growth curve, colony formation and transwell assays were involved to estimate cell proliferation and migration.

RESULTS

Tim-3 expression was significantly increased in both peripheral blood monocytes and TAMs in patients with HCC. The Tim-3 expression in monocytes/TAMs strongly correlated with higher tumour grades and the poor survival of patients with HCC. Consistently, HCC conditioned medium or transforming growth factor-β fostered Tim-3 expression and the alternative activation of macrophages. Moreover, Tim-3 interference in macrophages significantly inhibited the alternative activation of macrophages and suppressed HCC cell growth both in vitro and in vivo. Blocking interleukin 6 reversed the Tim-3-mediated effects on HCC cell growth in vitro.

CONCLUSIONS

Tim-3 displays critical roles in microenvironment-induced activation and protumoral effects of TAMs in HCC. Interference of Tim-3 might be great potential in HCC therapy.

Therapeutic targeting of GSK3β enhances the Nrf2 antioxidant response and confers hepatic cytoprotection in hepatitis C

OBJECTIVE

Impaired adaptive response to oxidative injuries is a fundamental mechanism central to the pathogenesis of chronic hepatitis C (CHC). Glycogen synthase kinase (GSK) 3β is an indispensable regulator of the oxidative stress response. However, the exact role of GSK3β in CHC is uncertain and was examined.

DESIGN

GSK3β and Nrf2 signalling pathways were examined in JFH1 HCV infected Huh7.5.1 hepatocytes, and also in liver biopsy specimens from CHC patients.

RESULTS

HCV infection elicited prominent Nrf2 antioxidant response in hepatocytes, marked by elevated expression of the Nrf2-dependent molecule haem oxygenase-1 and subsequent protection from apoptotic cell death. Inhibitory phosphorylation of GSK3β seems to be essential and sufficient for HCV-induced Nrf2 response. Mechanistically, GSK3β associated and physically interacted with Nrf2 in hepatocytes. In silico analysis revealed that Nrf2 encompasses multiple GSK3β phosphorylation consensus motifs, denoting Nrf2 as a cognate substrate of GSK3β. In the presence of TGFβ1, the HCV-induced GSK3β phosphorylation was blunted via a protein phosphatase 1-dependent mechanism and the cytoprotective Nrf2 response drastically impaired. This effect was counteracted by lithium, a selective inhibitor of GSK3β. In liver biopsy specimens from CHC patients, the expression of phosphorylated GSK3β positively correlated with Nrf2 expression and was inversely associated with the degree of liver injury. Moreover, CHC patients who received long-term lithium carbonate therapy primarily for concomitant psychiatric disorders exhibited much less liver injury, associated with enhanced hepatic expression of Nrf2.

CONCLUSIONS

Inhibition of GSK3β exerts hepatoprotection in CHC possibly through its direct regulation of Nrf2 antioxidant response.

Moving towards personalised therapy in patients with hepatocellular carcinoma: the role of the microenvironment

The goal of personalised therapy based on hepatocellular carcinoma (HCC) molecular characteristics is still beyond our grasp. Systemic treatments show poor efficacy, mainly because of the great heterogeneity of the tumour. Indeed, differences in aetiology, disease stage and biochemical composition of the fibrotic liver make cirrhosis itself a highly dyshomogeneous disease. Cancer cells grow in a cirrhotic microenvironment, interacting with stromal cells and engaging matrix components that differ from patient to patient, hampering the development of drugs to treat all patients. Growing evidence suggests a role for the cross-talk between HCC and the host stroma in driving disease progression and hence prognosis and survival. Many efforts have been devoted to identifying genes responsible for good or bad prognosis, but no study has yet proven helpful in guiding therapeutic choices and management over time, also taking into account the development of drug resistance. The questions of what to target and in which patient are still unsolved. In the personalised therapy scenario, the patient rather than the disease becomes the target of the therapy. However, this still requires an evidence-based medical approach. Herein, we will discuss how individual differences in terms of quality and quantity of the tissue microenvironment components affect progression of HCC. Then, we will highlight potential druggable pathways, also considering ongoing clinical trials. The development of biomarkers will be discussed in the light of new experimental research conducted with the aim of moving towards personalised therapy in patients with HCC.