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Gregory J Gores

Publications and source records attributed to Gregory J Gores.

At least 19 recordsLinked to original sources
PubMed2007

T cell targeting and phagocytosis of apoptotic biliary epithelial cells in primary biliary cirrhosis.

Primary biliary cirrhosis (PBC) is characterized by loss of tolerance against ubiquitously expressed mitochondrial autoantigens followed by biliary and salivary gland epithelial cell (BEC and SGEC) destruction by autoreactive T cells. It is unclear why BECs and SGECs are targeted. Previous work demonstrated that the reduced form of the major PBC autoantigen predominated in apoptotic BECs and SGECs as opposed to an oxidized form in other apoptotic cells. This led to the hypothesis that presentation of novel self-peptides from phagocytosed apoptotic BECs might contribute to BEC targeting by autoreactive T cells. The effect of autoantigen redox status on self-peptide formation was examined along with the phagocytic ability of BECs. Oxidation of PBC autoantigens first was shown to be due to protein S-glutathionylation of lipoyllysine residues. Absence of protein S-glutathionylation generated novel self-peptides and affected T cell recognition of a lipoyllysine containing peptide. Liver biopsy staining revealed BEC phagocytosis of apoptotic BECs (3.74+/-2.90% of BEC) was present in PBC (7 of 7 cases) but not in normal livers (0 of 3). BECs have the ability to present novel mitochondrial self-peptides derived from phagocytosed apoptotic BECs. Apoptotic cell phagocytosis by non-professional phagocytes may influence the tissue specificity of autoimmune diseases.

Animals↗
PubMed2006

Predictors of disease recurrence following neoadjuvant chemoradiotherapy and liver transplantation for unresectable perihilar cholangiocarcinoma.

BACKGROUND: Sixty-five patients with unresectable hilar cholangiocarcinoma (CCA) have undergone orthotopic liver transplantation (OLT) after neoadjuvant chemoradiotherapy per a clinical care protocol developed in 1993. We reviewed our experience with the aim to identify clinicopathological predictors of disease recurrence. METHODS: All patients with CCA that underwent OLT at our institution between 1993 and January 1, 2006 were treated in accord with our published protocol. We analyzed multiple clinical and explant pathologic factors using Cox regression analysis. RESULTS: Sixty-five patients with CCA underwent OLT. Four patients died within six months due to postoperative complications. At last follow-up, 11 patients (17%) had developed recurrence seven to 64 months after OLT. Mean time to recurrence was 29 months, and eight patients had died from recurrent disease. Patient and disease-free survival were 76% and 60% five years after OLT. Predictors of recurrence were older age, pretransplant cancer antigen (CA) 19-9 >100 U/ml, prior cholecystectomy, mass on cross-sectional imaging, residual tumor in explant >2 cm, tumor grade and perineural invasion in explant. Underlying primary sclerosing cholangitis, percutaneous biliary intubation, gender, and other time points for CA 19-9 were not associated with recurrence. Prolonged staging-to-OLT intervals for patients transplanted after implementation of model for end-stage liver disease (MELD) showed a trend toward increased recurrence. CONCLUSIONS: Older patients and those with high CA-19.9 levels, and larger tumors are more likely to develop recurrent disease. Prolonged waiting time may emerge as a significant risk factor with longer follow-up. These findings may guide patient selection, applicability of live donor transplantation and MELD score exceptions for this aggressive protocol.

Adult↗
PubMed2006

The human immunodeficiency virus type 1 tat protein enhances Cryptosporidium parvum-induced apoptosis in cholangiocytes via a Fas ligand-dependent mechanism.

While Cryptosporidium parvum infection of the intestine has been reported in both immunocompetent and immunocompromised individuals, biliary infection is seen primarily in adult AIDS patients and is associated with development of AIDS cholangiopathy. However, the mechanisms of pathogen-induced AIDS cholangiopathy remain unclear. Since we previously demonstrated that the Fas/Fas ligand (FasL) system is involved in paracrine-mediated C. parvum cytopathicity in cholangiocytes, we also tested the potential synergistic effects of human immunodeficiency virus type 1 (HIV-1) transactivator of transcription (Tat)-mediated FasL regulation on C. parvum-induced apoptosis in cholangiocytes by semiquantitative reverse transcription-PCR, immunoblotting, immunofluorescence analysis, and immunogold electron microscopy. H69 cells do not express CXCR4 and CCR5, which are receptors required for direct HIV-1 viral infection. However, recombinant biologically active HIV-1-associated Tat protein increased FasL expression in the cytoplasm of cholangiocytes without a significant increase in apoptosis. We found that C. parvum-induced apoptosis was associated with translocation of intracellular FasL to the cell membrane surface and release of full-length FasL from infected H69 cells. Tat significantly (P < 0.05) increased C. parvum-induced apoptosis in bystander cells in a dose-dependent manner. Moreover, Tat enhanced both C. parvum-induced FasL membrane translocation and release of full-length FasL. In addition, the FasL neutralizing antibody NOK-1 and the caspase-8 inhibitor Z-IETD-fmk both blocked C. parvum-induced apoptosis in cholangiocytes. The data demonstrated that HIV-1 Tat enhances C. parvum-induced cholangiocyte apoptosis via a paracrine-mediated, FasL-dependent mechanism. Our results suggest that concurrent active HIV replication, with associated production of Tat protein, and C. parvum infection synergistically increase cholangiocyte apoptosis and thus jointly contribute to AIDS-related cholangiopathies.

Animals↗
PubMed2006

Cholangiocarcinoma: modern advances in understanding a deadly old disease.

Cholangiocarcinomas are tumors that arise anywhere in the biliary tract, presumably of cholangiocyte origin. The global incidence of this rare disease is on the rise. Several known risk factors exist, and link chronic biliary inflammation to the pathogenesis of cholangiocarcinoma. Among these, amplification of the epidermal growth factor receptor, the interleukin-6 signaling pathway, inducible nitric oxide, erb-2, and cyclooxygenase-2 are well defined. Most patients present late, with a median survival of months. Although, imaging studies and clinical context often indicate cholangiocarcinoma, pathologic and cytologic diagnosis is difficult to obtain. Advanced cytologic tests with fluorescence in situ hybridization or digital image analysis can increase diagnostic sensitivity. Surgical resection is the current therapy of choice for both intrahepatic and ductal cholangiocarcinomas. However, the 5-year survival is poor, with 60 to greater than 90% recurrence rates. In a single center experience, liver transplantation with neoadjuvant chemoirradiation, for highly selected patients, has a 5-year disease free survival of greater than 80%. Future targeted therapies will depend on a better understanding of the cellular and molecular biology of cholangiocarcinomas.

Bile Duct Neoplasms↗
PubMed2006

Advanced cytologic techniques for the detection of malignant pancreatobiliary strictures.

BACKGROUND & AIMS: Two advanced cytologic techniques for detecting aneuploidy-digital image analysis (DIA) and fluorescence in situ hybridization (FISH)-have recently been developed to help identify malignant pancreatobiliary strictures. The aim of this study was to assess the clinical utility of cytology, DIA, and FISH for the identification of malignant pancreatobiliary strictures. METHODS: Brush cytologic specimens from 233 consecutive patients undergoing endoscopic retrograde cholangiopancreatography for pancreatobiliary strictures were examined by all 3 (cytology, DIA, and FISH) techniques. Strictures were stratified as proximal (n = 33) or distal (n = 114) based on whether they occurred above or below the cystic duct, respectively. Strictures in patients with primary sclerosing cholangitis (n = 86) were analyzed separately. RESULTS: Despite the stratification, the performances of the tests were similar. Conventional cytology has a low sensitivity (4%-20%) but 100% specificity. Because of the high specificity for cytology, we assessed the performance of the other tests when conventional cytology was negative. In this clinical context, FISH had an increased sensitivity (35%-60%) when assessing for chromosomal gains (polysomy) while preserving the specificity of cytology. The sensitivity and specificity of DIA was intermediate as compared with routine cytology and FISH but was additive to FISH values demonstrating only trisomy of chromosome 7 or chromosome 3. CONCLUSIONS: These findings suggest that FISH and DIA increase the sensitivity for the diagnosis of malignant pancreatobiliary tract strictures over that obtained by conventional cytology while maintaining an acceptable specificity.

Adolescent↗
PubMed2006

Proteasome inhibition attenuates hepatic injury in the bile duct-ligated mouse.

Proteasome inhibition has recently been demonstrated to inhibit hepatic fibrogenesis in the bile duct-ligated (BDL) mouse by blocking stellate cell NF-kappaB activation. The effect of proteasome inhibition on liver injury, however, is unclear. Our aims were to assess the effect of the proteasome inhibitor bortezomib on liver injury in the BDL mouse. Liver injury was assessed in 7-day BDL mice treated with a single dose of bortezomib on day 4 after bile duct ligation. Despite NF-kappaB inhibition by bortezomib, liver injury and hepatocyte apoptosis were reduced in treated BDL mice. The antiapoptotic effect of bortezomib was likely mediated by an increase in hepatic cellular FLICE inhibitory protein (c-FLIP) levels, a potent antiapoptotic protein. Unexpectedly, numerous mitotic hepatocytes were observed in the bortezomib-treated BDL mice liver specimens. Consistent with this observation, PCNA immunoreactivity and cyclin A protein expression were also increased with bortezomib treatment. Bortezomib therapy was also associated with a decrease in numbers and activation of Kupffer cells/macrophages. In conclusion, these data suggest that the proteasome inhibitor bortezomib reduces hepatocyte injury in the BDL mouse by mechanisms associated with a reduction in hepatocyte apoptosis, a decrease in Kupffer cell/macrophage number and activation, and increased hepatocyte proliferation.

Animals↗
PubMed2006

A novel endoscopic approach to brachytherapy in the management of Hilar cholangiocarcinoma.

OBJECTIVES: Traditionally, biliary brachytherapy sources are placed percutaneously via transhepatic drains or endoscopically via nasobiliary tubes (NBT). Another ERCP is needed for stent replacement after NBT removal. The aim of this study was to determine the feasibility and safety of endoscopic transpapillary insertion of irradiation sources through 10-Fr stents. METHODS: Medical records of Mayo Clinic Rochester patients undergoing biliary brachytherapy for hilar cholangiocarcinoma (CCA) were reviewed. Patients were part of a treatment protocol with curative intent including external beam radiation therapy (4,500 cGy), radiation sensitization (5-FU), and low dose rate (LDR) brachytherapy (<3,000 cGy) followed by liver transplantation. The 10-Fr biliary stent placed across the malignant biliary stricture was directly cannulated using a radiopaque (192)Ir embedded ribbon within a 300-cm long, 5.1-Fr plastic sheath. After withdrawal of the endoscope, the external end of the brachytherapy catheter was rerouted transnasally and secured. Each patient was hospitalized in a shielded room up to 24 h after which the brachytherapy catheter was removed by hand. RESULTS: Between 1999 and 2004, 32 patients underwent biliary brachytherapy via endoscopically placed 10-Fr plastic stents (mean age 50.6 yr, 69% PSC, bilateral brachytherapy catheters 28.1%). The technical complication observed was immediate brachytherapy catheter displacement (7 of 32, 22%) managed by prompt brachytherapy catheter repositioning. CONCLUSION: LDR biliary brachytherapy administration via endoscopically placed biliary stents is technically feasible and appears reasonably safe in select patients with unresectable perihilar CCA. Unlike NBTs, stents can potentially be placed in bilateral ductal systems to accommodate dual brachytherapy catheters when indicated.

Bile Duct Neoplasms↗
PubMed2006

Induction of intrahepatic cholangiocellular carcinoma by liver-specific disruption of Smad4 and Pten in mice.

Cholangiocellular carcinoma (CC), the second most common primary liver cancer, is associated with a poor prognosis. It has been shown that CCs harbor alterations of a number of tumor-suppressor genes and oncogenes, yet key regulators for tumorigenesis remain unknown. Here we have generated a mouse model that develops CC with high penetrance using liver-specific targeted disruption of tumor suppressors SMAD4 and PTEN. In the absence of SMAD4 and PTEN, hyperplastic foci emerge exclusively from bile ducts of mutant mice at 2 months of age and continue to grow, leading to tumor formation in all animals at 4-7 months of age. We show that CC formation follows a multistep progression of histopathological changes that are associated with significant alterations, including increased levels of phosphorylated AKT, FOXO1, GSK-3beta, mTOR, and ERK and increased nuclear levels of cyclin D1. We further demonstrate that SMAD4 and PTEN regulate each other through a novel feedback mechanism to maintain an expression balance and synergistically repress CC formation. Finally, our analysis of human CC detected PTEN inactivation in a majority of p-AKT-positive CCs, while about half also lost SMAD4 expression. These findings elucidate the relationship between SMAD4 and PTEN and extend our understanding of CC formation.

Animals↗
PubMed2006

Free fatty acids induce JNK-dependent hepatocyte lipoapoptosis.

Elevated serum free fatty acids (FFAs) and hepatocyte lipoapoptosis are features of non-alcoholic fatty liver disease. However, the mechanism by which FFAs mediate lipoapoptosis is unclear. Because JNK activation is pivotal in both the metabolic syndrome accompanying non-alcoholic fatty liver disease and cellular apoptosis, we examined the role of JNK activation in FFA-induced lipoapoptosis. Multiple hepatocyte cell lines and primary mouse hepatocytes were treated in culture with monounsaturated fatty acids and saturated fatty acids. Despite equal cellular steatosis, apoptosis and JNK activation were greater during exposure to saturated versus monounsaturated FFAs. Inhibition of JNK, pharmacologically as well as genetically, reduced saturated FFA-mediated hepatocyte lipoapoptosis. Cell death was caspase-dependent and associated with mitochondrial membrane depolarization and cytochrome c release indicating activation of the mitochondrial pathway of apoptosis. JNK-dependent lipoapoptosis was associated with activation of Bax, a known mediator of mitochondrial dysfunction. As JNK can activate Bim, a BH3 domain-only protein capable of binding to and activating Bax, its role in lipoapoptosis was also examined. Small interfering RNA-targeted knock-down of Bim attenuated both Bax activation and cell death. Collectively the data indicate that saturated FFAs induce JNK-dependent hepatocyte lipoapoptosis by activating the proapoptotic Bcl-2 proteins Bim and Bax, which trigger the mitochondrial apoptotic pathway.

Animals↗
PubMed2006

Bax inhibition protects against free fatty acid-induced lysosomal permeabilization.

Lysosomal permeabilization is a key feature of hepatocyte lipotoxicity, yet the mechanisms mediating this critical cellular event are unclear. This study examined the mechanisms involved in free fatty acid (FFA)-induced lysosomal permeabilization and the role of Bax, a Bcl-2 family member, in this event. Exposure of liver cells to palmitate induced Bax activation and translocation to lysosomes. Studies to suppress Bax activation either by pharmacological approaches or small interfering-RNA-mediated inhibition of Bax expression showed that lysosomal permeabilization is Bax dependent. In addition, palmitate treatment resulted in a significant decrease in Bcl-X(L), a Bax antagonist. Moreover, forced Bcl-X(L) expression blocked lysosomal permeabilization. Lysosomal permeabilization by FFA was ceramide and caspase independent. Finally, paradigms that inhibit lysosomal permeabilization also reduced apoptosis. In conclusion, these data strongly support a regulatory role for Bax in FFA-mediated lysosomal permeabilization and subsequent cell death.

Animals↗
PubMed2006

Deaths on the liver transplant waiting list: an analysis of competing risks.

The usual method of estimating survival probabilities, namely the Kaplan-Meier method, is suboptimal in the analysis of deaths on the transplant waiting list. Death, transplantation, and withdrawal from list must all be considered. In this analysis, we applied the competing risk analysis method, which allows evaluating these end points individually and simultaneously, to compare the risk of waiting list death across era, blood types, liver disease diagnosis, and severity (Model for End-stage Liver Disease; MELD). Of 861 patients registered on the waiting list at Mayo Clinic Rochester between 1990 and 1999, 657 (76%) patients underwent transplantation, 82 (10%) died while waiting, 41 (5%) withdrew from the list, and 81 (9%) patients were still waiting as of February 2002. The risk of death at 3 years was 10% by the competing risk analysis. During the study period, the median time to transplantation increased from 45 to 517 days. In univariate analyses, there was no significant difference in the risk of death by era of listing (P = .25) or blood type (P = .31), whereas the risk of death was significantly higher in patients with alcohol-induced liver disease and those with higher MELD score (P < .01). A multivariable analysis showed that after adjusting for MELD, blood type, and diagnosis, patients listed in the latter era had higher mortality. In conclusion, the competing risk analysis method is useful in estimating the risk of death among patients awaiting liver transplantation.

Adult↗
PubMed2006

Proteasome inhibition induces hepatic stellate cell apoptosis.

Induction of hepatic stellate cell (HSC) apoptosis attenuates hepatic fibrosis, and, therefore, mechanisms to induce HSC cell death are of therapeutic interest. Proteasome inhibitors induce apoptosis in transformed cells, especially those cells dependent upon nuclear factor kappa B (NF-kappaB) activation. Because stimulated HSCs also trigger NF-kappaB activation, the aim of this study was to determine if proteasome inhibitors induce HSC apoptosis. The immortalized human HSC line, LX-2, and primary rat HSCs were treated with the proteasome inhibitors bortezomib and MG132. Both proteasome inhibitors induced HSC apoptosis. Proteasome inhibition blocked NF-kappaB activation and, more importantly, NF-kappaB inhibition by Bay11-7082-triggered HSC apoptosis. Activated HSC survival is dependent upon the NF-kappaB target gene A1, an anti-apoptotic Bcl-2 family member, as siRNA targeted knockdown of A1-induced HSC apoptosis. In contrast, proteasome inhibition-induced alterations in TRAIL, death receptor 5, and Bim could not be implicated in the apoptotic response. The relevance of these findings was confirmed in the bile-duct-ligated mouse where bortezomib reduced hepatic markers of stellate cell activation and fibrosis. In conclusion, proteasome inhibition is a potential therapeutic strategy for inducing HSC apoptosis and inhibiting liver fibrogenesis.

Animals↗
PubMed2006

Apoptosis and necrosis in the liver: a tale of two deaths?

Death of hepatocytes and other hepatic cell types is a characteristic feature of liver diseases as diverse as cholestasis, viral hepatitis, ischemia/reperfusion, liver preservation for transplantation and drug/toxicant-induced injury. Cell death typically follows one of two patterns: oncotic necrosis and apoptosis. Necrosis is typically the consequence of acute metabolic perturbation with ATP depletion as occurs in ischemia/reperfusion and acute drug-induced hepatotoxicity. Apoptosis, in contrast, represents the execution of an ATP-dependent death program often initiated by death ligand/death receptor interactions, such as Fas ligand with Fas, which leads to a caspase activation cascade. A common event leading to both apoptosis and necrosis is mitochondrial permeabilization and dysfunction, although the mechanistic basis of mitochondrial injury may vary in different settings. Prevention of these modes of cell death is an important target of therapy, but controversies still exist regarding which mode of cell death predominates in various forms of liver disease and injury. Resolution of these controversies may come with the recognition that apoptosis and necrosis frequently represent alternate outcomes of the same cellular pathways to cell death, especially for cell death mediated by mitochondrial permeabilization. An understanding of processes leading to liver cell death will be important for development of effective interventions to prevent hepatocellular death leading to liver failure and to promote cancer and stellate cell death in malignancy and fibrotic disease.

Acetaminophen↗
PubMed2006

Constitutive androstane receptor (CAR) ligand, TCPOBOP, attenuates Fas-induced murine liver injury by altering Bcl-2 proteins.

The constitutive androstane receptor (CAR) modulates xeno- and endobiotic hepatotoxicity by regulating detoxification pathways. Whether activation of CAR may also protect against liver injury by directly blocking apoptosis is unknown. To address this question, CAR wild-type (CAR+/+) and CAR knockout (CAR-/-) mice were treated with the CAR agonist 1,4-bis[2-(3,5-dichloropyridyloxy)] benzene (TCPOBOP) and then with the Fas agonist Jo2 or with concanavalin A (ConA). Following the administration of Jo2, hepatocyte apoptosis, liver injury, and animal fatalities were abated in TCPOBOP-treated CAR+/+ but not in CAR-/- mice. Likewise, acute and chronic ConA-mediated liver injury and fibrosis were also reduced in wild-type versus CAR(-/-) TCPOBOP-treated mice. The proapoptotic proteins Bak (Bcl-2 antagonistic killer) and Bax (Bcl-2-associated X protein) were depleted in livers from TCPOBOP-treated CAR+/+ mice. In contrast, mRNA expression of the antiapoptotic effector myeloid cell leukemia factor-1 (Mcl-1) was increased fourfold. Mcl-1 promoter activity was increased by transfection with CAR and administration of TCPOBOP in hepatoma cells, consistent with a direct CAR effect on Mcl-1 transcription. Indeed, site-directed mutagenesis of a putative CAR consensus binding sequence on the Mcl-1 promoter decreased Mcl-1 promoter activity. Mcl-1 transgenic animals demonstrated little to no acute liver injury after administration of Jo2, signifying Mcl-1 cytoprotection. In conclusion, these observations support a prominent role for CAR cytoprotection against Fas-mediated hepatocyte injury via a mechanism involving upregulation of Mcl-1 and, likely, downregulation of Bax and Bak.

Animals↗
PubMed2006

Primary sclerosing cholangitis: summary of a workshop.

Primary sclerosing cholangitis (PSC) is a rare but important liver disease that leads to cirrhosis and need for liver transplantation in a high proportion of cases. The disease occurs in approximately 1 per 100,000 population per year, usually presents in adulthood, and affects men more often than women. Typical serum biochemical results, autoantibodies and liver biopsy are suggestive but not diagnostic of PSC, the diagnosis requiring cholangiographic demonstration of stricturing and dilatation of the intra- and/or extra-hepatic bile ducts. The natural history of PSC is variable, the average survival being 12 to 17 years. The cause of PSC is still unknown. Although considered an autoimmune disease, PSC has several atypical features and a strong genetic component. The therapy of PSC is unsatisfactory. Standard doses of ursodeoxycholic acid (UDCA) lead to improvements in biochemical abnormalities but not in histology, cholangiographic appearance or survival. Several innovative therapies have been tried in PSC, but with scant evidence of benefit. For patients with high grade strictures, endoscopic dilatation is beneficial. Liver transplantation is successful for end-stage liver disease due to PSC and improves survival. PSC may recur after transplantation but is rarely progressive. The most dreaded complication of PSC is cholangiocarcinoma. Diagnosis of this highly malignant tumor is difficult, and there are no biomarkers for its early detection. Liver transplantation for cholangiocarcinoma has an exceedingly poor outcome, although transplantation with neoadjuvant chemoirradiation holds promise in selected patients. Thus, significant opportunities remain for basic and clinical research into the cause, natural history, and therapy of PSC.

Biopsy↗
PubMed2006

Liver transplantation for gastroenteropancreatic neuroendocrine cancers: Defining selection criteria to improve survival.

Liver transplantation for gastroenteropancreatic neuroendocrine cancer (GEP) is controversial. The aim of this study was to assess patient outcomes after liver transplantation for hepatic metastases from GEP. Medical records of patients who underwent liver transplantation for GEP were reviewed. Immunohistochemistry for assessing the Ki67 proliferation index was performed on explanted liver tissue. Nineteen patients who underwent liver transplantation had a mean follow-up of 22 months with a range of 0 to 84 months. There was 1 intraoperative death, and 3 patients had disease recurrence after liver transplantation leading to death in 1 patient. Overall estimated 1-year survival for 17 patients included in the treatment protocol (mean follow-up, 15 months) was 87% with an estimated 1-year recurrence-free rate (conditional on survival) of 77%. Three of 11 patients with pancreatic islet cell GEP developed disease recurrence, whereas all 8 patients with carcinoid GEP remain free of disease. Analysis of the Ki67 proliferation index in 18 patients did not differentiate those with recurrence from those without disease recurrence. In conclusion, liver transplantation for patients with hepatic metastases from GEP is a viable therapeutic option in highly selected patients.

Adult↗