Willscott E. Naugler

The wolf in sheep's clothing: the role of interleukin-6 in immunity, inflammation and cancer

Recent discoveries involving the cytokine interleukin (IL)-6 have originated from diverse disciplines, revealing roles in biological processes that are likewise varied. The most novel findings suggest a connection between inflammation and diseases, such as insulin resistance associated with diabetes mellitus and cancer, which had not or only weakly been appreciated previously. The IL-6 pathway is one of the mechanisms linking inflammation to these disease processes. In addition, new evidence points toward IL-6 as one of the mediators coordinating the interface between adaptive and innate immunity. Here, we review the evidence linking IL-6 to inflammatory diseases and cancer.

NF-κB and Cancer — Identifying Targets and Mechanisms

A connection between inflammation and carcinogenesis has long been known, but the precise mechanisms are just beginning to be understood. NF-kappaB proteins, transcription factors which integrate stress signals and orchestrate immune responses, have also recently been linked to carcinogenesis. Hallmarks of cancer development include self-sufficiency in growth signals, insensitivity to growth-inhibitors, evasion of apoptosis, limitless replicative potential, tissue invasion and metastasis, and sustained angiogenesis. NF-kappaB signaling has been implicated in each of these hallmarks, and recent experimental studies have illuminated the mechanistic pathways by which NF-kappaB signaling contributes to these aspects of carcinogenesis. This review will focus on recent experimental data supporting the hypothesis that inflammation promotes carcinogenesis, and that NF-kappaB signaling is at the heart of such inflammation.

Saturated fatty acids inhibit induction of insulin gene transcription by JNK-mediated phosphorylation of insulin-receptor substrates

JNKs are attractive targets for treatment of obesity and type-2 diabetes. A sustained increase in JNK activity was observed in dietary and genetic models of obesity in mice, whereas JNK deficiency prevented obesity-induced insulin resistance. A similar insulin-sensitizing effect was seen upon treatment of obese mice with JNK inhibitors. We now demonstrate that treatment with the saturated fatty acid palmitic acid results in sustained JNK activation and insulin resistance in primary mouse hepatocytes and pancreatic β-cells. In the latter, palmitic acid treatment inhibits glucose-induced insulin gene transcription, in part, by interfering with autocrine insulin signaling through phosphorylation of insulin-receptor substrates 1 and 2 at sites that interfere with binding to activated insulin receptors. This mechanism may account for the induction of central insulin resistance by free fatty acids.

Bipotential Adult Liver Progenitors Are Derived from Chronically Injured Mature Hepatocytes

Adult liver progenitor cells are biliary-like epithelial cells that emerge only under injury conditions in the periportal region of the liver. They exhibit phenotypes of both hepatocytes and bile ducts. However, their origin and their significance to injury repair remain unclear. Here, we used a chimeric lineage tracing system to demonstrate that hepatocytes contribute to the progenitor pool. RNA-sequencing, ultrastructural analysis, and in vitro progenitor assays revealed that hepatocyte-derived progenitors were distinct from their biliary-derived counterparts. In vivo lineage tracing and serial transplantation assays showed that hepatocyte-derived proliferative ducts retained a memory of their origin and differentiated back into hepatocytes upon cessation of injury. Similarly, human hepatocytes in chimeric mice also gave rise to biliary progenitors in vivo. We conclude that human and mouse hepatocytes can undergo reversible ductal metaplasia in response to injury, expand as ducts, and subsequently contribute to restoration of the hepatocyte mass.

Comparison of Oligonucleotide Ligation Assay and Consensus Sequencing for Detection of Drug-Resistant Mutants of Human Immunodeficiency Virus Type 1 in Peripheral Blood Mononuclear Cells and Plasma

ABSTRACT Drug-resistant mutants of human immunodeficiency virus type 1 (HIV-1) recede below the limit of detection of most assays applied to plasma when selective pressure is altered due to changes in antiretroviral treatment (ART). Viral variants with different mutations are selected by the new ART when replication is not suppressed or wild-type variants with greater replication fitness outgrow mutants following the cessation of ART. Mutants selected by past ART appear to persist in reservoirs even when not detected in the plasma, and when conferring cross-resistance they can compromise the efficacy of novel ART. Oligonucleotide ligation assay (OLA) of virus in plasma and peripheral blood mononuclear cells (PBMC) was compared to consensus sequence dideoxynucleotide chain terminator sequencing for detection of 91 drug resistance mutations that had receded below the limit of detection by sequencing of plasma. OLA of plasma virus detected 27.5% (95% confidence interval [CI], 19 to 39%) of mutant genotypes; consensus sequencing of the PBMC amplicon from the same specimen detected 23.1% (95% CI, 14 to 34%); and OLA of PBMC detected 53.8% (95% CI, 44 to 64%). These data suggest that concentrations of drug-resistant mutants were greater in PBMC than in plasma after changes in ART and indicate that the OLA was more sensitive than consensus sequencing in detecting low levels of select drug-resistant mutants.

Waiting time predicts survival after liver transplantation for hepatocellular carcinoma: A cohort study using the United Network for Organ Sharing registry

Recipients of liver transplantation (LT) for hepatocellular carcinoma (HCC) have an 8% to 20% risk of HCC recurrence. Single‐center studies suggest that a period of waiting after HCC therapy may facilitate the selection of patients at low risk for post‐LT HCC recurrence and mortality. We evaluated whether a longer waiting time after Model for End‐Stage Liver Disease (MELD) prioritization for HCC predicts longer post‐LT survival. From the United Network for Organ Sharing registry, we selected 2 groups registered for LT between March 2005 and March 2009: (1) HCC patients receiving MELD prioritization and (2) non‐HCC patients. Patients were stratified by their MELD status at LT (a marker of time on the wait list after HCC MELD prioritization) and were followed from LT until death or censoring through October 2012. By comparing post‐LT survival to intention‐to‐treat (ITT) survival from registration, we assessed predictors of post‐LT survival and estimated the benefit of LT. The median MELD scores at LT were 22 (HCC) and 24 (non‐HCC). A higher MELD score at LT was independently associated with lower post‐LT mortality in the HCC group [hazard ratio (HR) = 0.84, 95% confidence interval (CI) = 0.73‐0.98] and higher post‐LT mortality in the non‐HCC group (HR = 1.20, 95% CI = 1.15‐1.25). Compared with the HCC group, the non‐HCC group had lower post‐LT mortality [relative risk (RR) = 0.85, log‐rank P < 0.01] but higher ITT mortality (RR = 1.25, log‐rank P < 0.01) because of a 33 percentage point lower probability of undergoing LT. In conclusion, a longer waiting time before LT for HCC predicted longer post‐LT survival in a national transplant registry. Delaying LT for HCC may reduce disparities in ITT survival and access to LT among different indications and thereby improve system utility and organ allocation equity for the overall pool of LT candidates. Liver Transpl 20:1045–1056, 2014.

Survival and Cost-Effectiveness Analysis of Competing Strategies in the Management of Small Hepatocellular Carcinoma

The aim of the present study is to compare the survival rates and cost‐effectiveness of different treatment strategies for small (<2 cm) hepatocellular carcinoma (HCC). Markov chains are developed to model different management strategies for patients with compensated cirrhosis and small HCC. Probabilities of progression and survival and the likelihood of orthotopic liver transplantation are taken from the literature and incorporated into the models. As a starting population, 1000 patients are followed over a period of 10 years. Patients treated immediately with transarterial chemoembolization (TACE) or radiofrequency ablation (RFA) live as long as or longer than patients who are monitored expectantly with the intention of liver transplantation once the HCC has grown larger than 2 cm and a higher transplant priority score becomes available. With TACE, immediate treatment results in an average survival time of 4.269 years versus 4.324 years with the monitoring strategy. With RFA, immediate treatment results in an average survival time of 5.273 years versus 5.236 years with the monitoring strategy. In addition, the cost analysis shows that immediate treatment with either TACE or RFA is less expensive than monitoring. The better cost‐effectiveness of immediate therapy versus the monitoring strategy remains robust and unaffected by variations of the assumptions built into the model. In conclusion, in patients with compensated cirrhosis and small HCC, a strategy of immediate treatment with either TACE or RFA prevails over a strategy of expectant monitoring with the intention of transplantation. Liver Transpl 16:1186–1194, 2010.

Bile Acid Flux Is Necessary for Normal Liver Regeneration

Background & Aims Many signals governing liver regeneration (LR) following 2/3 partial hepatectomy (PH) are recognized, but the primary signal(s) remains unknown. The aim of the study was to confirm that the remnant liver after PH lacks capacity to secrete the BA pool returning via the enterohepatic ciruculation (EHC), which may in turn stimulate LR. Methods After standard PH, BA flux was documented and BA signaling (Fgf15) and synthesis (Cyp7a) determined by qPCR. Rat biliary fistula (BF) and Asbt knockout mouse models interrupted the EHC prior to PH, and standard assays for LR employed along with complete RNA sequencing. CCl4 intoxication after BF tested the hypothesis in an alternate injury model. Results BA rise in systemic blood immediately following PH, confirming that the remnant liver cannot handle the BA returning via portal circulation. When the BA pool is drained prior to PH in the rat BF model, LR is markedly attenuated, a phenomenon reversed with duodenal BA replacement. Hepatocyte proliferation is similarly attenuated after PH in the Asbt knockout mouse as well as after CCl44 intoxication in rats with BF. Complete RNA sequencing in the rat PH model shows that early c-jun and AP-1 gene expression pathways are down regulated in the absence of BA, coincident with attenuated LR. Conclusions Absent BA return to the liver after PH or CCl4 injury markedly attenuates LR, though hepatocyte proliferation still occurs, inferring that BA flux and signaling are not the sole signals governing LR. Transcriptional networks involving c-jun and AP-1 are involved in the BA-specific effects on hepatocyte proliferation.

Malignant infiltration of the liver presenting as acute liver failure.

There have been few reports of acute liver failure (ALF), with encephalopathy and coagulopathy, caused by infiltration of the liver by malignant cells. We describe a case series of 27 patients with ALF caused by malignancy. We examined a large, multicenter ALF registry (1910 patients; mean age, 47.1 ± 13.9 y) and found only 27 cases (1.4%) of ALF attributed to malignancy. Twenty cases (74%) presented with abdominal pain and 11 presented with ascites. The most common malignancies included lymphoma or leukemia (33%), breast cancer, (30%), and colon cancer (7%); 90% of the patients with lymphoma or leukemia had no history of cancer, compared with 25% of patients with breast cancer. Overall, 44% of the patients had evidence of liver masses on imaging. Diagnosis was confirmed by biopsy in 15 cases (55%) and by autopsy for 6 cases. Twenty-four patients (89%) died within 3 weeks of ALF.

Impact of locoregional therapy and alpha‐fetoprotein on outcomes in transplantation for liver cancer: a UNOS Region 6 pooled analysis

Liver transplantation (LT) provides optimal long‐term disease‐free survival for hepatocellular carcinoma (HCC). High pre‐LT alpha‐fetoprotein (AFP) has been associated with HCC recurrence, but it is unclear whether a drop in AFP or locoregional therapy impacts survival/recurrence after LT. LT‐recipients transplanted for HCC in three centers (UNOS Region 6) were reviewed (2006–2009) for demographics, tumor characteristics, locoregional therapy, AFP, recurrence, and survival. Among 211 LT recipients (mean age 56.4 yr, 83% male, mean MELD 12.2), 94% met Milan criteria and 61% received locoregional therapy. Mean disease‐free survival (DFS) was 1549.7 d, and 84% are currently alive. Factors affecting DFS included recurrence (RR, 0.074; 95% CI, 0.038–0.14), normal peak AFP (29.6, 95% CI, 2.96–296.3), peak AFP >400 (RR, 0.15; 95% CI, 0.03–0.73) and AFP at LT >400 (RR, 15.5; 95% CI, 2.4–100.5). Twenty‐one patients had recurrence and were more likely beyond Milan criteria (5/23(21%) vs. 8/220 (4%), p = 0.0038), with peak AFP >400 and AFP at LT >400 (p = 0.001). Locoregional therapy did not affect mean DFS (1458.0 vs. 1603.8 d, p = 0.05) or recurrence (12.5% vs. 6%). Predictors of recurrence were similar to previous studies, including high AFP and tumor outside Milan criteria. While locoregional therapy itself did not affect DFS/recurrence, a decrease in AFP pre‐transplant appears to positively influence outcomes in those who received locoregional therapy.