Evaluation of markers of immunity in different metastatic immune microenvironments suggests more suppression within breast to liver metastases in breast cancer.

PURPOSE: Programmed death receptor ligand-1 (PD-L1) expression and tumor mutational burden (TMB) are approved screening biomarkers for immune checkpoint inhibition (ICI) in advanced triple negative breast cancer. We examined these biomarkers along with characterization of the tumor microenvironment (TME) between breast tumors (BrTs), axillary metastases (AxMs), liver metastases (LvMs), non-axillary lymph node metastases, and non-liver metastases to determine differences related to site of metastatic disease. METHODS: 3076 unpaired biopsies from breast cancer patients were analyzed using whole transcriptome sequencing and NextGen DNA depicting TMB within tumor sites. The PD-L1 positivity was determined with VENTANA PD-L1 (SP142) assay. The immune cell fraction within the TME was calculated by QuantiSeq and MCP-counter. RESULTS: Compared to BrT, more LvM samples had a high TMB (≥ 10 mutations/Mb) and fewer LvM samples had PD-L1+ expression. Evaluation of the TME revealed that LvM sites harbored lower infiltration of adaptive immune cells, such as CD4+, CD8+, and regulatory T-cells compared with the BrT foci. We saw differences in innate immune cell infiltration in LvM compared to BrT, including neutrophils and NK cells. CONCLUSIONS: LvMs are less likely to express PD-L1+ tumor cells but more likely to harbor high TMB as compared to BrTs. Unlike AxMs, LvMs represent a more immunosuppressed TME and demonstrate lower gene expression associated with adaptive immunity compared to BrTs. These findings suggest biopsy site be considered when interpreting results that influence ICI use for treatment and further investigation of immune composition and biomarkers expression by metastatic site.

Interaction of RIPK1 and A20 modulates MAPK signaling in murine acetaminophen toxicity.

Acetaminophen (APAP)-induced liver necrosis is a form of regulated cell death (RCD) in which APAP activates the mitogen-activated protein kinases (MAPKs) and specifically the c-Jun-N-terminal kinase (JNK) pathway, leading to necrotic cell death. Previously, we have shown that receptor interacting protein kinase-1 (RIPK1) knockdown is also protective against APAP RCD upstream of JNK. However, whether the kinase or platform function of RIPK1 is involved in APAP RCD is not known. To answer this question, we used genetic mouse models of targeted hepatocyte RIPK1 knockout (RIPK1HepCKO) or kinase dead knock-in (RIPK1D138N) and adult hepatocyte specific knockout of the cytoprotective protein A20 (A20HepCKO), known to interact with RIPK1, to study its potential involvement in MAPK signaling. We observed no difference in injury between WT and RIPK1D138N mice post APAP. However, RIPK1HepCKO was protective. We found that RIPK1HepCKO mice had attenuated pJNK activation, while A20 was simultaneously upregulated. Conversely, A20HepCKO markedly worsened liver injury from APAP. Mechanistically, we observed a significant upregulation of apoptosis signal-regulating kinase 1 (ASK1) and increased JNK activation in A20HepCKO mice compared with littermate controls. We also demonstrated that A20 coimmunoprecipitated (co-IP) with both RIPK1 and ASK1, and that in the presence of RIPK1, there was less A20-ASK1 association than in its absence. We conclude that the kinase-independent platform function of RIPK1 is involved in APAP toxicity. Adult RIPK1HepCKO mice are protected against APAP by upregulating A20 and attenuating JNK signaling through ASK1, conversely, A20HepCKO worsens injury from APAP.

We Are Not Immune: Racial and Ethnic Disparities in Autoimmune Liver Diseases.

Autoimmune liver diseases are attributed to a complex interplay of biologic, acquired, and environmental factors. Increased prevalence, later stage at presentation, worse response to standard therapy, and transplant-related disparities have all been reported in racial and ethnic minorities such as Black and Latinx patients with autoimmune liver diseases. While biology and inherited genetic predispositions may partly explain these disparities, definitive and universal genetic variations underlying these differences in outcomes have not been defined. Nonetheless, socioeconomic status, access to health care, environmental and societal factors, and implicit provider bias can all contribute to poor patient outcomes. There remains an unmet need to understand and mitigate the factors contributing to health inequity in autoimmune liver diseases. In this review, we summarize the data on racial and ethnic disparities in presentation, treatment response, and outcomes pertaining to autoimmune liver diseases in minority populations, on the premise that understanding disparities is the first step toward reaching health equity.

IgG:IgM Ratios of Liver Plasma Cells Reveal Similar Phenotypes of Primary Biliary Cholangitis With and Without Features of Autoimmune Hepatitis.

Within the spectrum of autoimmune liver diseases, there are patients who manifest features of more than one disease, which was previously identified as having overlap syndrome1,2 and is now referred to as variant syndromes. The most common variant syndrome is between primary biliary cholangitis (PBC) and autoimmune hepatitis (AIH). Typically, AIH presents with elevated serum immunoglobulin (Ig) G, whereas PBC is associated with elevated serum IgM.3,4 Previous studies have suggested that plasma cells in liver biopsies of AIH patients are predominantly IgG+, whereas in PBC, there is an abundance of IgM+ cells.5,6 We wanted to determine the immunostaining pattern for IgG and IgM of liver plasma cells among Hispanic patients in Los Angeles with features of both PBC-AIH compared with those with PBC or AIH alone.

Cell Death in Liver Diseases: A Review.

Regulated cell death (RCD) is pivotal in directing the severity and outcome of liver injury. Hepatocyte cell death is a critical event in the progression of liver disease due to resultant inflammation leading to fibrosis. Apoptosis, necrosis, necroptosis, autophagy, and recently, pyroptosis and ferroptosis, have all been investigated in the pathogenesis of various liver diseases. These cell death subroutines display distinct features, while sharing many similar characteristics with considerable overlap and crosstalk. Multiple types of cell death modes can likely coexist, and the death of different liver cell populations may contribute to liver injury in each type of disease. This review addresses the known signaling cascades in each cell death pathway and its implications in liver disease. In this review, we describe the common findings in each disease model, as well as the controversies and the limitations of current data with a particular focus on cell death-related research in humans and in rodent models of alcoholic liver disease, non-alcoholic fatty liver disease and steatohepatitis (NASH/NAFLD), acetaminophen (APAP)-induced hepatotoxicity, autoimmune hepatitis, cholestatic liver disease, and viral hepatitis.

The Receptor Interacting Protein Kinases in the Liver.

The receptor interacting serine/threonine kinase1 and 3 (RIPK1, RIPK3) are regulators of cell death and survival. RIPK1 kinase activity is required for necroptosis and apoptosis, while its scaffolding function is necessary for survival. Although both proteins can mediate apoptosis, RIPK1 and RIPK3 are most well-known for their role in the execution of necroptosis via the mixed lineage domain like pseudokinase. Necroptosis is a caspase-independent regulated cell death program which was first described in cultured cells with unknown physiologic relevance in the liver. Many recent reports have suggested that RIPK1 and/or RIPK3 participate in liver disease pathogenesis and cell death. Notably, both proteins have been shown to mediate inflammation independent of cell death. Whether necroptosis occurs in hepatocytes, and how it is executed in the presence of an intact caspase machinery is controversial. In spite of this controversy, it is evident that RIPK1 and RIPK3 participate in many experimental liver disease models. Therefore, in addition to cell death signaling, their necroptosis-independent role warrants further examination.

Knockdown of RIPK1 Markedly Exacerbates Murine Immune-Mediated Liver Injury through Massive Apoptosis of Hepatocytes, Independent of Necroptosis and Inhibition of NF-κB.

Receptor-interacting protein kinase (RIPK)1 has an essential role in the signaling pathways triggered by death receptors through activation of NF-κB and regulation of caspase-dependent apoptosis and RIPK3/mixed lineage kinase domain-like protein (MLKL)-mediated necroptosis. We examined the effect of RIPK1 antisense knockdown on immune-mediated liver injury in C57BL/6 mice caused by α-galactosylceramide (αGalCer), a specific activator for invariant NKT cells. We found that knockdown of RIPK1 markedly exacerbated αGalCer-mediated liver injury and induced lethality. This was associated with increased hepatic inflammation and massive apoptotic death of hepatocytes, as indicated by TUNEL staining and caspase-3 activation. Pretreatment with zVAD.fmk, a pan-caspase inhibitor, or neutralizing Abs against TNF, almost completely protected against the exacerbated liver injury and lethality. Primary hepatocytes isolated from RIPK1-knockdown mice were sensitized to TNF-induced cell death that was completely inhibited by adding zVAD.fmk. The exacerbated liver injury was not due to impaired hepatic NF-κB activation in terms of IκBα phosphorylation and degradation in in vivo and in vitro studies. Lack of RIPK1 kinase activity by pretreatment with necrostatin-1, a RIPK1 kinase inhibitor, or in the RIPK1 kinase-dead knock-in (RIPK1D138N) mice did not exacerbate αGalCer-mediated liver injury. Furthermore, RIPK3-knockout and MLKL-knockout mice behaved similarly as wild-type control mice in response to αGalCer, with or without knockdown of RIPK1, excluding a switch to RIPK3/MLKL-mediated necroptosis. Our findings reveal a critical kinase-independent platform role for RIPK1 in protecting against TNF/caspase-dependent apoptosis of hepatocytes in immune-mediated liver injury.

Randomized trial of 1-week versus 2-week intervals for endoscopic ligation in the treatment of patients with esophageal variceal bleeding.

UNLABELLED: The appropriate interval between ligation sessions for treatment of esophageal variceal bleeding is uncertain. The optimal interval would provide variceal eradication as rapidly as possible to lessen early rebleeding while minimizing ligation-induced adverse events. We randomly assigned patients hospitalized with acute esophageal variceal bleeding who had successful ligation at presentation to repeat ligation at 1-week or 2-week intervals. Beta-blocker therapy was also prescribed. Ligation was performed at the assigned interval until varices were eradicated and then at 3 and 9 months after eradication. The primary endpoint was the proportion of patients with variceal eradication at 4 weeks. Four-week variceal eradication occurred more often in the 1-week than in the 2-week group: 37/45 (82%) versus 23/45 (51%); difference = 31%, 95% confidence interval 12%-48%. Eradication occurred more rapidly in the 1-week group (18.1 versus 30.8 days, difference = -12.7 days, 95% confidence interval -20.0 to -5.4 days). The mean number of endoscopies to achieve eradication or to the last endoscopy in those not achieving eradication was comparable in the 1-week and 2-week groups (2.3 versus 2.1), with the mean number of postponed ligation sessions 0.3 versus 0.1 (difference = 0.2, 95% confidence interval -0.02 to 0.4). Rebleeding at 4 weeks (4% versus 4%) and 8 weeks (11% versus 9%), dysphagia/odynophagia/chest pain (9% versus 2%), strictures (0% versus 0%), and mortality (7% versus 7%) were similar with 1-week and 2-week intervals. CONCLUSION: One-week ligation intervals led to more rapid eradication than 2-week intervals without an increase in complications or number of endoscopies and without a reduction in rebleeding or other clinical outcomes; the decision regarding ligation intervals may be individualized based on patient and physician preferences and local logistics and resources. (Hepatology 2016;64:549-555).