PPP1R15A-expressing monocytic MDSCs promote immunosuppressive liver microenvironment in fibrosis-associated hepatocellular carcinoma.

Background & Aims: Recent studies demonstrated the importance of fibrosis in promoting an immunosuppressive liver microenvironment and thereby aggressive hepatocellular carcinoma (HCC) growth and resistance to immune checkpoint blockade (ICB), particularly via monocyte-to-monocytic myeloid-derived suppressor cell (M-MDSC) differentiation triggered by hepatic stellate cells (HSCs). We thus aimed to identify druggable targets in these immunosuppressive myeloid cells for HCC therapy. Methods: M-MDSC signature genes were identified by integrated transcriptomic analysis of a human HSC-monocyte culture system and tumor-surrounding fibrotic livers of patients with HCC. Mechanistic and functional studies were conducted using in vitro-generated and patient-derived M-MDSCs. The therapeutic efficacy of a M-MDSC targeting approach was determined in fibrosis-associated HCC mouse models. Results: We uncovered over-expression of protein phosphatase 1 regulatory subunit 15A (PPP1R15A), a myeloid cell-enriched endoplasmic reticulum stress modulator, in human M-MDSCs that correlated with poor prognosis and ICB non-responsiveness in patients with HCC. Blocking TGF-ß signaling reduced PPP1R15A expression in HSC-induced M-MDSCs, whereas treatment of monocytes by TGF-ß upregulated PPP1R15A, which in turn promoted ARG1 and S100A8/9 expression in M-MDSCs and reduced T-cell proliferation. Consistently, lentiviral-mediated knockdown of Ppp1r15a in vivo significantly reduced ARG1+S100A8/9+ M-MDSCs in fibrotic liver, leading to elevated intratumoral IFN-γ+GZMB+CD8+ T cells and enhanced anti-tumor efficacy of ICB. Notably, pharmacological inhibition of PPP1R15A by Sephin1 reduced the immunosuppressive potential but increased the maturation status of fibrotic HCC patient-derived M-MDSCs. Conclusions: PPP1R15A+ M-MDSC cells are involved in immunosuppression in HCC development and represent a novel potential target for therapies. Impact and implications: Our cross-species analysis has identified PPP1R15A as a therapeutic target governing the anti-T-cell activities of fibrosis-associated M-MDSCs (monocytic myeloid-derived suppressor cells). The results from the preclinical models show that specific inhibition of PPP1R15A can break the immunosuppressive barrier to restrict hepatocellular carcinoma growth and enhance the efficacy of immune checkpoint blockade. PPP1R15A may also function as a prognostic and/or predictive biomarker in patients with hepatocellular carcinoma.

Metformin suppresses interleukin-22 induced hepatocellular carcinoma by upregulating Hippo signaling pathway.

BACKGROUND AND AIMS: Epidemiological studies have shown direct associations between type 2 diabetes and the risk of cancers. Accumulating evidence indicates that metformin is profoundly implicated in preventing tumor development. However, the exact mechanism underlying the antitumor effects of metformin in hepatocellular carcinoma (HCC) is still not clear. METHODS: In this study, we investigated the effects of metformin on a mouse HCC model and interleukin-22 (IL-22)-associated carcinogenesis in vitro. RESULTS: We found that metformin significantly suppressed the incidence and tumor burden of HCC in the diethyl-nitrosamine-induced HCC mouse model. As expected, the expression of IL-22, an important factor involved in HCC progression, was markedly reduced by metformin. Treatment of HCC cells with metformin inhibited IL-22 induced cell proliferation, migration, and invasion, and promoted cell apoptosis. Furthermore, ectopic expression of IL-22 makes HCC more aggressive, whereas metformin largely compromised it in vitro and in vivo. Mechanistically, the whole transcriptome analysis and functional analysis revealed that Hippo signaling pathway was involved in the antitumor ability of metformin. Consistent with this, metformin directly inhibited LATS1/2 and activated Mst1/2, phosphorylated YAP1 in vitro. After blocking the Hippo pathway by XMU-MP-1, the inhibitor of MST1/2, the inhibitory effects by metformin were dramatically attenuated as shown by in vitro study. CONCLUSIONS: Collectively, our findings illuminate a new regulatory mechanism, metformin activates Hippo signaling pathway to regulate IL-22 mediated HCC progression and provide new insights into its tumor-suppressive roles.

Preliminary clinical experience applying donor-derived cell-free DNA to discern rejection in pediatric liver transplant recipients.

Donor-derived cell-free DNA (dd-cfDNA) has been of major interest recently as a non-invasive marker of graft injury, but has not yet been extensively tested in children. From May to September in 2019, a total of 76 pediatric patients receiving a liver graft were enrolled and there were 27 patients excluded. Ultimately plasma samples and matched liver specimens from 49 patients were successfully collected whenever rejection was suspected clinically. Dd-cfDNA were analyzed and then compared to biopsy. Of these, 11 (22.4%) patients were found to have rejection by biopsy. Dd-cfDNA levels were higher among patients with rejection compared to those with no rejection. In subgroup analysis, dd-cfDNA% among patients with rejection differed from those with EBV/CMV infection and DILI patients. Similarly, observations were available concerning dd-cfDNA (cp/mL). The AUC for dd-cfDNA% and dd-cfDNA (cp/mL) were 0.878, 0.841, respectively, both of which were higher than conventional LFTs. For rejection, dd-cfDNA% ≥ 28.7% yielded a sensitivity of 72.7%, specificity 94.7% and dd-cfDNA (cp/mL) ≥ 2076 cp/mL, yielded a sensitivity of 81.8%, specificity 81.9%. Of note, the dd-cfDNA distribution was significantly different between whole liver and LLS transplantation. In the setting of pediatric LTx, dd-cfDNA appears to be a sensitive biomarker indicating the presence of rejection.International Clinical Trails Registry Platform: ChiCTR1900022406.

Dual Effect of Hepatic Macrophages on Liver Ischemia and Reperfusion Injury during Liver Transplantation.

Ischemia-reperfusion injury (IRI) is a major complication in liver transplantation (LT) and it is closely related to the recovery of grafts' function. Researches has verified that both innate and adaptive immune system are involved in the development of IRI and Kupffer cell (KC), the resident macrophages in the liver, play a pivotal role both in triggering and sustaining the sterile inflammation. Damage-associated molecular patterns (DAMPs), released by the initial dead cell because of the ischemia insult, firstly activate the KC through pattern recognition receptors (PRRs) such as toll-like receptors. Activated KCs is the dominant players in the IRI as it can secret various pro-inflammatory cytokines to exacerbate the injury and recruit other types of immune cells from the circulation. On the other hand, KCs can also serve in a contrary way to ameliorate IRI by upregulating the anti-inflammatory factors. Moreover, new standpoint has been put forward that KCs and macrophages from the circulation may function in different way to influence the inflammation. Managements towards KCs are expected to be the effective way to improve the IRI.

Clinical analysis of liver transplantation in autoimmune liver diseases.

BACKGROUND: Autoimmune liver diseases (ALDs) consist of autoimmune hepatitis (AIH), primary biliary cirrhosis (PBC), primary sclerosing cholangitis (PSC), IgG4-associated cholangitis and overlap syndromes. Patients with these diseases may gradually progress to end-stage liver diseases and need liver transplantation. The present study aimed to explore the prognosis of patients with ALDs after liver transplantation. METHODS: The clinical data of 80 patients with ALD (24 cases of AIH, 35 of PBC, 15 of PSC and 6 of AIH-PBC overlap syndromes) who underwent liver transplantation in Renji Hospital, Shanghai Jiao Tong University School of Medicine from June 2004 to September 2016 were collected retrospectively. The causes of death were analyzed and the postoperative cumulative survival rate was estimated by the Kaplan-Meier method. Recurrence and other complications were also analyzed. RESULTS: Of the 80 patients, 18 were males and 62 were females. The average age was 50.5 years and the average Model for End-stage Liver Disease (MELD) score was 14.1. After a median follow-up of 19.8 months, 8 patients died. The 1-, 3- and 5-year cumulative survival rates were all 89.0%. Three cases of recurrent ALDs were diagnosed (3.8%) but they were not totally consistent with primary diseases. Biliary tract complication occurred in 10 patients (12.5%). The new onset of tumor was observed in 1 patient (1.3%). De novo HBV/CMV/EBV infection was found in 3, 8 and 3 patients, respectively. CONCLUSION: Liver transplantation is an effective and safe treatment for end-stage ALD.

Improved portal vein venoplasty with an autogenous patch in pediatric living donor liver transplantation.

A stenotic or hypoplastic portal vein (PV) represents a challenge for PV reconstruction in pediatric living donor liver transplantation (LDLT). Several PV venoplastic techniques have been developed. However, we still seek improved venoplastic techniques with better efficacy and compatibility. From June 2016 to July 2017, 271 LDLT procedures were performed at the Department of Liver Surgery, Renji Hospital. A total of 16 consecutive children with stenotic and sclerotic PVs underwent a novel technique-the autogenous PV patch plastic technique. Vessel patches were procured from the left branch (LB), or the bifurcation of the right branch and LB of the PV in the native liver. Then, the PVs were enlarged by suturing the patches along the longitudinal axis from the confluence of the PV and coronary vein (CV). In this series, 15/16 achieved good intraoperational PV flow, and 1 showed low PV flow but was treated with stent placement. Within a median follow-up of 11 months (1-18 months), 15 patients were alive and had normal graft function, whereas 1 child died from lung infection 1 month after transplantation. No PV complications were detected. In conclusion, the autogenous patch venoplasty technique using the PV-CV confluence is simple and safe. This novel venoplastic reconstruction technique could serve as a surgical option to achieve satisfactory outcomes, especially those with stenotic PV (<4.5 mm) and dilated CV (>3.0 mm). Liver Transplantation 2018 AASLD.