Bi, Yan

INTRODUCTION: Solid organ transplant recipients are at increased risk of de novo malignancies, in some cases up to 15.6%. Data regarding pancreatic cancer following liver transplantation is limited. We aim to evaluate the incidence of pancreatic adenocarcinoma among liver transplant recipients in the United States. Describe survival in those patients and identify subgroup of patients at increased risk. METHODS: We examined the United Network of Organ Sharing (UNOS) database and identified patients with pancreatic adenocarcinoma who underwent liver transplant between 1988 and 2016. Patients 18 years of age and older were included. Demographics, primary diagnosis and survival data were recorded. Kaplan-Meier survival analyses and log-rank tests were performed. RESULTS: In the UNOS database, survival data regarding 142,488 patients was available and the cause of death was identified in 14,533 liver transplant recipients. A total of 140 patients developed pancreatic adenocarcinoma after liver transplantation. Most common indications for transplantations were Hepatitis C, alcohol cirrhosis and hepatocellular carcinoma (25 [17.9%], 24 [17.1%] and 9 [6.4%] respectively). Annual incidence was 16 pancreatic cancer cases per 100,000 transplant recipients. Compared to national annual incidence of 12.9 cancer cases per 100,000 patients, the relative risk was 1.23 (95% CI 0.59–2.56). Compared to other liver transplant recipients, those who developed pancreatic cancer were older and transplanted earlier in the time period evaluated ( P < 0.001 and P = 0.002 respectively). Gender, ethnicity, BMI, and primary diagnosis (i.e., transplant indication) were not significantly different among groups. Patient survival was significantly lower in patients who developed pancreatic adenocarcinoma (Log-rank test P < 0.001) (Figure 1). CONCLUSION: Analysis of the UNOS database showed that pancreatic adenocarcinoma is increased among liver transplant recipients without reaching statistical significance. Primary indications for transplantation and demographics were similar among both groups. Our findings suggest that pancreatic adenocarcinoma is more likely associated to long-standing immunosuppression and non-traditional risk factors rather than alcohol consumption or obesity. Further studies describing the natural history of pancreatic cancer after solid organ transplantation are suggested.

INTRODUCTION: Immunoglobulin G4-related sclerosing cholangitis (IgG4-SC) has been recognized worldwide. However, its natural history and long-term outcomes are not well known. METHODS: In this retrospective, single center, cohort study, we identified patients who received a diagnosis of IgG4-SC at Mayo Clinic Rochester from 1999 to 2018. The diagnosis of IgG4-SC was rigorously ascertained by review of medical records and using the validated HISORt criteria. Comprehensive clinical data was extracted from patients' charts. Long-term outcomes of interest included cirrhosis, cholangiocarcinoma (CCA), and death. To compare outcomes, a random sample of PSC patients was selected in a 1:1 ratio matched for age of diagnosis and gender. Survival analyses were performed for comparisons using the Kaplan-Meier method, and log-rank test, and the cumulative incidence of cirrhosis and CCA was assessed using the competing risks regression method. RESULTS: A total of 61 patients were diagnosed with IgG4-SC during the study period. The median age of diagnosis was 66 years (IQR: 56–71 years), 85% were male, and the median follow-up was 6.1 years (IQR: 3.2–8.3 years). The pancreas was the most commonly involved extra-biliary organ (93%). Fifty-five patients received prednisone of whom 96% experienced complete or partial remission. Sixteen patients received rituximab as maintenance therapy, of whom 88% maintained remission. Three patients (5%) developed cirrhosis, and 2 patients (3%) developed CCA. Nine patients (15%) died; 2 due to cirrhosis, 2 due to CCA, 1 due to pancreatic cancer, and 4 due to non-hepatobiliary causes. Patients with IgG4-SC had significantly lower 5- and 10-year cumulative incidence of developing cirrhosis (5 y: 4% vs. 34%; 10 y: 6% vs. 43%; P < 0.001) and CCA (5 y: 3% vs. 17%; 10 y: 4% vs. 22%; P = 0.012) compared with PSC patients. Two patients in the PSC group underwent liver transplantation, while none in the IgG4-SC group. Overall 5- and 10-year survival was greater in the IgG4-SC cohort (5 y: 92% vs. 70%; 10 y: 77% vs. 57%; P = 0.02). CONCLUSION: Patients with IgG4-SC, the majority of whom received treatment, have a small potential risk of long-term hepatobiliary complications. Their risk of cirrhosis, CCA and death, was lower than in patients with PSC. The better outcome in the IgG4-SC group is likely due to the benefit of treatment. Surveillance in this population needs further assessment, especially the subset that does receive or respond to treatment.

Intra-acinar trypsinogen activation occurs in the earliest stages of pancreatitis and is believed to play important roles in pancreatitis pathogenesis. However, the exact role of intra-acinar trypsin activity in pancreatitis remains elusive. Here, we aimed to examine the specific effects of intra-acinar trypsin activity on the development of pancreatitis using a transgenic mouse model. This transgenic mouse model allowed for the conditional expression of a mutant trypsinogen that can be activated specifically inside pancreatic acinar cells. We found that expression of this active mutated trypsin had no significant effect on triggering spontaneous pancreatitis. Instead, several protective compensatory mechanisms, including SPINK1 and heat shock proteins, were upregulated. Notably, these transgenic mice developed much more severe acute pancreatitis, compared with control mice, when challenged with caerulein. Elevated tissue edema, serum amylase, inflammatory cell infiltration and acinar cell apoptosis were dramatically associated with increased trypsin activity. Furthermore, chronic pathological changes were observed in the pancreas of all transgenic mice, including inflammatory cell infiltration, parenchymal atrophy and cell loss, fibrosis, and fatty replacement. These changes were not observed in control mice treated with caerulein. The alterations in pancreata from transgenic mice mimicked the histological changes common to human chronic pancreatitis. Taken together, we provided in vivo evidence that increased intra-acinar activation of trypsinogen plays an important role in the initiation and progression of both acute and chronic pancreatitis. NEW & NOTEWORTHY Trypsinogen is activated early in pancreatitis. However, the roles of trypsin in the development of pancreatitis have not been fully addressed. Using a genetic approach, we showed trypsin activity is critical for the severity of both acute and chronic pancreatitis.

Replacement of the exocrine parenchyma by fibrous tissue is a main characteristic of chronic pancreatitis. Understanding the mechanisms of pancreatic fibrogenesis is critical for the development of preventive and therapeutic interventions. Cyclooxygenase-2 (COX-2), a rate-limiting enzyme for prostaglandin synthesis, is expressed in patients with chronic pancreatitis. However, it is unknown whether COX-2 can cause chronic pancreatitis. To investigate the roles of pancreatic acinar COX-2 in fibrogenesis and the development of chronic pancreatitis, COX-2 was ectopically expressed specifically in pancreatic acinar cells in transgenic mice. Histopathological changes and expression levels of several profibrogenic factors related to chronic pancreatitis were evaluated. COX-2 was expressed in the pancreas of the transgenic mice, as detected by Western blot analysis. Immunohistochemical staining showed COX-2 was specifically expressed in pancreatic acinar cells. COX-2 expression led to progressive changes in the pancreas, including pancreas megaly, persistent inflammation, collagen deposition, and acinar-to-ductal metaplasia. Quantitative RT-PCR and immunostaining showed that profibrogenic factors were upregulated and pancreatic stellate cells were activated in the COX-2 transgenic mice. Expression of COX-2 in pancreatic acinar cells is sufficient to induce chronic pancreatitis. Targeting this pathway may be valuable in the prevention of chronic pancreatitis. NEW & NOTEWORTHY COX-2 expression is observed in pancreatic tissues of human chronic pancreatitis. In this study, we showed that COX-2 expression caused the development of chronic pancreatitis in transgenic mice, supporting the idea that COX-2 inhibition may be an effective preventive and therapeutic strategy.

Animal models of pancreatitis are useful for elucidating the pathogenesis of pancreatitis and developing and testing novel interventions. In this review, we aim to summarize the most commonly used animal models, overview their pathophysiology, and discuss their strengths and limitations. We will also briefly describe common animal study procedures and refer readers to more detailed protocols in the literature. Although animal models include pigs, dogs, opossums, and other animals, we will mainly focus on rodent models because of their popularity. Autoimmune pancreatitis and genetically engineered animal models will be reviewed elsewhere.

Chronic passive hepatic congestion (congestive hepatopathy) leads to hepatic fibrosis; however, the mechanisms involved in this process are not well understood. We developed a murine experimental model of congestive hepatopathy through partial ligation of the inferior vena cava (pIVCL). C57BL/6 and transgenic mice overexpressing tissue factor pathway inhibitor (SM22α‐TFPI) were subjected to pIVCL or sham. Liver and blood samples were collected and analyzed in immunohistochemical, morphometric, real‐time polymerase chain reaction, and western blot assays. Hepatic fibrosis and portal pressure were significantly increased after pIVCL concurrent with hepatic stellate cell (HSC) activation. Liver stiffness, as assessed by magnetic resonance elastography, correlated with portal pressure and preceded fibrosis in our model. Hepatic sinusoidal thrombosis as evidenced by fibrin deposition was demonstrated both in mice after pIVCL as well as in humans with congestive hepatopathy. Warfarin treatment and TFPI overexpression both had a protective effect on fibrosis development and HSC activation after pIVCL. In vitro studies show that congestion stimulates HSC fibronectin (FN) fibril assembly through direct effects of thrombi as well as by virtue of mechanical strain. Pretreatment with either Mab13 or Cytochalasin‐D, to inhibit β‐integrin or actin polymerization, respectively, significantly reduced fibrin and stretch‐induced FN fibril assembly. Conclusion : Chronic hepatic congestion leads to sinusoidal thrombosis and strain, which in turn promote hepatic fibrosis. These studies mechanistically link congestive hepatopathy to hepatic fibrosis. (H epatology 2015;61:648‐659)

Hepatic stellate cells (HSCs) generate matrix, which in turn may also regulate HSCs function during liver fibrosis. We hypothesized that HSCs may endocytose matrix proteins to sense and respond to changes in microenvironment. Primary human HSCs, LX2, or mouse embryonic fibroblasts (MEFs) [wild-type; c-abl−/−; or Yes, Src, and Fyn knockout mice (YSF−/−)] were incubated with fluorescent-labeled collagen or gelatin. Fluorescence-activated cell sorting analysis and confocal microscopy were used for measuring cellular internalization of matrix proteins. Targeted PCR array and quantitative real-time PCR were used to evaluate gene expression changes. HSCs and LX2 cells endocytose collagens in a concentration- and time-dependent manner. Endocytosed collagen colocalized with Dextran 10K, a marker of macropinocytosis, and 5-ethylisopropyl amiloride, an inhibitor of macropinocytosis, reduced collagen internalization by 46%. Cytochalasin D and ML7 blocked collagen internalization by 47% and 45%, respectively, indicating that actin and myosin are critical for collagen endocytosis. Wortmannin and AKT inhibitor blocked collagen internalization by 70% and 89%, respectively, indicating that matrix macropinocytosis requires phosphoinositide-3-kinase (PI3K)/AKT signaling. Overexpression of dominant-negative dynamin-2 K44A blocked matrix internalization by 77%, indicating a role for dynamin-2 in matrix macropinocytosis. Whereas c-abl−/− MEF showed impaired matrix endocytosis, YSF−/− MEF surprisingly showed increased matrix endocytosis. It was also associated with complex gene regulations that related with matrix dynamics, including increased matrix metalloproteinase 9 (MMP-9) mRNA levels and zymographic activity. HSCs endocytose matrix proteins through macropinocytosis that requires a signaling network composed of PI3K/AKT, dynamin-2, and c-abl. Interaction with extracellular matrix regulates matrix dynamics through modulating multiple gene expressions including MMP-9.