Edward R. Abril

Early hepatic microvascular injury in response to acetaminophen toxicity.

Objective: The hepatic toxic response to acetaminophen (APAP) is characterized by centrilobular (CL) necrosis preceded by hepatic microvascular injury and congestion. The present study was conducted to examine changes in liver microcirculation after APAP dosing.

Ethanol and cytokine secretion

Cytokines are regulatory polypeptides secreted during the generation of an immune or inflammatory response by lymphocytes, cells of the monocyte/macrophage series, and a variety of other cell types. Alterations in the production, site of action, or metabolism of cytokines by exogenous factors, such as ethanol (EtOH), may have deleterious effects on the immune system as a whole. EtOH has been implicated in the onset of a variety of immune defects in vivo including effects on the production of cytokines critically involved in inflammatory responses (tumor necrosis factor, interleukin 1 and interleukin 6). In this review, we examine current knowledge regarding the effects of EtOH on the release of cytokines in humans and in animal models, in vitro and in vivo, which may help to elucidate the adverse actions of EtOH on mammalian immune systems.

Changes in lymphocyte subsets and macrophage functions from high, short-term dietary ethanol in C57/BL6 mice

Chronic administration of a diet containing 7% ethanol (36% of total calories) for 8 days to male C57/BL6 mice resulted in significant changes in functioning of macrophages. Peritoneal exudate macrophages from the ethanol-fed mice released more tumor cell cytotoxic materials upon culturing in vitro than cells from controls. However, peritoneal exudate cells continued to respond to exogenous beta carotene in vitro to produce additional cytotoxic materials. Phagocytosis of sheep red blood cells in vitro was suppressed in cells from ethanol treated mice. The number of splenic lymphocytes of various subsets was significantly changed by the ethanol exposure. Total T cells and T suppressor cells were lower, with a significant decrease in B cells containing IgM on their surface. The percentage of spleen cells showing markers for macrophage functions and their activation were significantly reduced. It is concluded that short-term chronic consumption of dietary ethanol, which was sufficient to produce physical dependence, results in significant alterations in lymphocyte subtypes and suppression of some macrophage functions.

Beta-carotene stimulates human leukocytes to secrete a novel cytokine.

The effect of beta‐carotene on cytokine production by human peripheral blood leukocytes was tested. Beta‐carotene stimulated the secretion of a novel cytotoxic cytokine when peripheral blood cells were exposed to carotenoid concentrations between 10‐6 and 10‐10M. Beta‐carotene–treated supernatants caused the cytolysis of four out of the six human tumor cell lines tested. Low level toxicity was also observed when normal diploid fibroblast lines were exposed to beta‐carotene–treated leukocyte supernatants. The cytotoxic activity elicited by beta‐carotene was found to be distinct from characterized cytokines based on both antisera neutralization and target cell specificity studies. This study demonstrates that beta‐carotene can induce human leukocytes to secrete one or more cytokines that can manifest cytotoxic activity against human tumor cells in vitro.

Dietary steatotic liver attenuates acetaminophen hepatotoxicity in mice.

Objective: To determine whether hepatic steatosis is susceptible to acetaminophen (APAP) hepatotoxicity.

Ethanol Binging Enhances Hepatic Microvascular Responses to Acetaminophen in Mice

Objective: Chronic alcoholism has been considered to be a risk for acetaminophen (APAP) hepatotoxicity, but little is known about the effect of binge alcohol drinking on APAP‐induced liver injury. The present study was conducted to examine the effect of ethanol binging on APAP‐induced hepatic microcirculatory dysfunction.

Nanoparticle delivery of an AKT/PDK1 inhibitor improves the therapeutic effect in pancreatic cancer

The K-ras mutation in pancreatic cancer can inhibit drug delivery and increase drug resistance. This is exemplified by the therapeutic effect of PH-427, a small molecule inhibitor of AKT/PDK1, which has shown a good therapeutic effect against a BxPC3 pancreatic cancer model that has K-ras, but has a poor therapeutic effect against a MiaPaCa-2 pancreatic cancer model with mutant K-ras. To increase the therapeutic effect of PH-427 against the MiaPaCa-2 pancreatic cancer model with mutant K-ras, we encapsulated PH-427 into poly(lactic-co-glycolic acid) nanoparticles (PNP) to form drug-loaded PH-427-PNP. PH-427 showed a biphasic release from PH-427-PNP over 30 days during studies in sodium phosphate buffer, and in vitro studies revealed that the PNP was rapidly internalized into MiaPaCa-2 tumor cells, suggesting that PNP can improve PH-427 delivery into cells harboring mutant K-ras. In vivo studies of an orthotopic MiaPaCa-2 pancreatic cancer model showed reduced tumor load with PH-427-PNP as compared with treatment using PH-427 alone or with no treatment. Ex vivo studies confirmed the in vivo results, suggesting that PNP can improve drug delivery to pancreatic cancer harboring mutant K-ras.

Effects of acetaminophen on hepatic microcirculation in mice

Acetaminophen (APAP) intoxication from overdosing can result in severe hepatic damage, which is characterized by hemorrhagic centrilobular necrosis and by towering the levels of transaminase. The APAP-induced hepatic necrosis is preceded by centrilobular microvascular congestion thought to be due to collapse of the sinusoidal wall and the infiltration of blood elements into the space of Disse [1]. These findings suggest that, in addition to direct hepatocellular damage, sinusoidal endothelial cells (SECs) participate in liver injury elicited by APAP overdose. As a result, the present study was conducted to examine changes in hepatic microcirculation after APAP administration using in vivo microscopic methods.

Time-serial Assessment of Drug Combination Interventions in a Mouse Model of Colorectal Carcinogenesis Using Optical Coherence Tomography

Optical coherence tomography (OCT) is a high-resolution, nondestructive imaging modality that enables time-serial assessment of adenoma development in the mouse model of colorectal cancer. In this study, OCT was utilized to evaluate the effectiveness of interventions with the experimental antitumor agent α-difluoromethylornithine (DFMO) and a nonsteroidal anti-inflammatory drug sulindac during early [chemoprevention (CP)] and late stages [chemotherapy (CT)] of colon tumorigenesis. Biological endpoints for drug interventions included OCT-generated tumor number and tumor burden. Immunochistochemistry was used to evaluate biochemical endpoints [Ki-67, cleaved caspase-3, cyclooxygenase (COX)-2, β-catenin]. K-Ras codon 12 mutations were studied with polymerase chain reaction-based technique. We demonstrated that OCT imaging significantly correlated with histological analysis of both tumor number and tumor burden for all experimental groups (P < 0.0001), but allows more accurate and full characterization of tumor number and burden growth rate because of its time-serial, nondestructive nature. DFMO alone or in combination with sulindac suppressed both the tumor number and tumor burden growth rate in the CP setting because of DFMO-mediated decrease in cell proliferation (Ki-67, P < 0.001) and K-RAS mutations frequency (P = 0.04). In the CT setting, sulindac alone and DFMO/sulindac combination were effective in reducing tumor number, but not tumor burden growth rate. A decrease in COX-2 staining in DFMO/sulindac CT groups (COX-2, P < 0.01) confirmed the treatment effect. Use of nondestructive OCT enabled repeated, quantitative evaluation of tumor number and burden, allowing changes in these parameters to be measured during CP and as a result of CT. In conclusion, OCT is a robust minimally invasive method for monitoring colorectal cancer disease and effectiveness of therapies in mouse models.

Does mutated K-RAS oncogene attenuate the effect of Sulindac in colon cancer chemoprevention?

The NSAID sulindac has been successfully used alone or in combination with other agents to suppress colon tumorigenesis in patients with genetic predisposition and also showed its efficacy in prevention of sporadic colon adenomas. At the same time, some experimental and clinical reports suggest that a mutant K-RAS oncogene may negate sulindac antitumor efficacy. To directly assess sulindac activity at suppressing premalignant lesions carrying K-RAS mutation, we utilized a novel mouse model with an inducible colon-specific expression of the mutant K-ras oncogene (K-rasG12D). Tumor development and treatment effects were monitored by minimally invasive endoscopic Optical coherence tomography. Expression of the mutant K-ras allele accelerated azoxymethane (AOM)-induced colon carcinogenesis in C57BL/6 mice, a strain otherwise resistant to this carcinogen. Sulindac completely prevented AOM-induced tumor formation in K-ras wild-type (K-ras wt) animals. In K-rasG12D–mutant mice, a 38% reduction in tumor number, an 83% reduction in tumor volume (P ≤ 0.01) and an increase in the number of adenoma-free mice (P = 0.04) were observed. The partial response of K-RasG12D animals to sulindac treatment was evident by the decrease in mucosal thickness (P < 0.01) and delay in progression of the precancerous aberrant crypt foci to adenomas. Molecular analyses showed significant induction in cyclooxygenase 2 (COX-2), cleaved caspase-3 (CC3), and Ki-67 expression by AOM, but not sulindac treatment, in all genotypes. Our data underscore the importance of screening for K-RAS mutations in individuals with colon polyps to provide more personalized interventions targeting mutant K-RAS signaling pathways. Cancer Prev Res; 11(1); 16–26. ©2017 AACR.