Marion J. Pollheimer

Intramural and extramural vascular invasion in colorectal cancer: prognostic significance and quality of pathology reporting.

Blood vessel invasion has been associated with poor outcome in colorectal cancer (CRC), whereas the prognostic impact of lymphatic invasion is less clear. The authors of this report evaluated venous and lymphatic invasion as potential prognostic indicators in patients with CRC focusing on lymph node‐negative patients and compared routine and review pathology diagnoses.

Tumor necrosis is a new promising prognostic factor in colorectal cancer

The prognostic significance of tumor necrosis in colorectal cancer is unclear. Our study aimed to analyze the prognostic value of tumor necrosis with respect to progression-free and cancer-specific survival and to relate findings to expression of proteins involved in the control of cancer cell death, such as p53 and bcl-2. A total of 381 colorectal cancer specimens were retrospectively reevaluated. The extent of tumor necrosis was semiquantitatively assessed and recorded as either absent, focal (≤10% of the tumor area), moderate (10%-30%), or extensive (≥30%). Expression of p53 and bcl-2 was assessed immunohistochemically and recorded as either positive (using a cutoff value of 10%) or negative. In addition, mismatch repair protein status was assessed by immunohistochemistry using antibodies directed against hMLH1, hMSH2, and hMSH6. Tumor necrosis was observed in 365 (96%) cases, with 180 (47%) tumors showing focal necrosis, 119 (31%) moderate necrosis, and 66 (17%) extensive necrosis, respectively. Extent of necrosis was significantly associated with high T classification (P < .001), high N classification (P = .005), high International Union Against Cancer stage (P < .001), poor tumor differentiation (P < .001), large tumor size (P < .001), and blood vessel invasion (P = .01). No association of tumor necrosis with expression of p53, bcl-2, and mismatch repair protein status was observed. Tumor necrosis proved to be an independent prognostic variable with respect to progression-free and cancer-specific survival. In conclusion, tumor necrosis showed significant impact on prognosis of colorectal cancer patients. Its presence is readily assessable in hematoxylin and eosin-stained sections and should therefore routinely be commented upon in the pathology report.

Differential effects of norUDCA and UDCA in obstructive cholestasis in mice

Background & Aims The quest for effective drugs to treat cholangiopathies led to the development of norUDCA previously shown to have potent choleretic effects and to heal cholangiopathy in Abcb4 knockout (Abcb4−/−) mice. Its mother compound UDCA had detrimental effects in common bile duct ligated (CBDL) mice, presumably related to its choleretic effects. norUDCA choleretic effects may therefore raise safety concerns when used in cholangiopathies with biliary obstruction. We therefore aimed at comparing the effects of UDCA and norUDCA in clear-cut obstructive cholestasis. Methods 0.5% UDCA- or norUDCA-fed wild type and Abcb4−/− mice were subjected to CBDL or selective bile duct ligation (SBDL) and compared to controls with regard to liver injury. Bile flow, bile composition, and biliary manometry were compared in UDCA-fed, norUDCA-fed and control mice. Toxicity of UDCA and norUDCA was compared in vitro. Results Compared to UDCA, liver injury in CBDL mice was significantly lower in almost all norUDCA groups. In SBDL mice, only UDCA induced bile infarcts in the ligated lobes, whereas norUDCA even ameliorated liver injury. In vitro, UDCA induced cellular ATP depletion and was significantly more toxic than norUDCA in HepG2 cells, mouse bile duct epithelial cells, and primary human hepatocytes. Conclusions Compared to norUDCA, UDCA is significantly more toxic in CBDL mice. norUDCA, in contrast to UDCA, significantly ameliorates liver injury in SBDL mice. Our findings uncover profound differences in metabolism and therapeutic mechanisms of both bile acids with important clinical consequences.

Bile acids trigger cholemic nephropathy in common bile‐duct–ligated mice

Tubular epithelial injury represents an underestimated but important cause of renal dysfunction in patients with cholestasis and advanced liver disease, but the underlying mechanisms are unclear. To address the hypothesis that accumulation and excessive alternative urinary elimination of potentially toxic bile acids (BAs) may contribute to kidney injury in cholestasis, we established a mouse model for detailed in vivo time course as well as treatment studies. Three‐day common bile duct ligation (CBDL) induced renal tubular epithelial injury predominantly at the level of aquaporin 2–positive collecting ducts with tubular epithelial and basement membrane defects. This was followed by progressive interstitial nephritis and tubulointerstitial renal fibrosis in 3‐, 6‐, and 8‐week CBDL mice. Farnesoid X receptor knockout mice (with a hydrophilic BA pool) were completely protected from CBDL‐induced renal fibrosis. Prefeeding of hydrophilic norursodeoxycholic acid inhibited renal tubular epithelial injury in CBDL mice. In addition, we provide evidence for renal tubular injury in cholestatic patients with cholemic nephropathy. Conclusion: We characterized a novel in vivo model for cholemic nephropathy, which offers new perspectives to study the complex pathophysiology of this condition. Our findings suggest that urinary‐excreted toxic BAs represent a pivotal trigger for renal tubular epithelial injury leading to cholemic nephropathy in CBDL mice. (Hepatology 2013; 58:2056–2069)

Absence of adipose triglyceride lipase protects from hepatic endoplasmic reticulum stress in mice.

Nonalcoholic fatty liver disease (NAFLD) is characterized by triglyceride (TG) accumulation and endoplasmic reticulum (ER) stress. Because fatty acids (FAs) may trigger ER stress, we hypothesized that the absence of adipose triglyceride lipase (ATGL/PNPLA2)–the main enzyme for intracellular lipolysis, releasing FAs, and closest homolog to adiponutrin (PNPLA3) recently implicated in the pathogenesis of NAFLD–protects against hepatic ER stress. Wild‐type (WT) and ATGL knockout (KO) mice were challenged with tunicamycin (TM) to induce ER stress. Serum biochemistry, hepatic TG and FA profiles, liver histology, and gene expression for markers of hepatic lipid metabolism, ER stress, and inflammation were explored. Moreover, cell‐culture experiments were performed in Hepa1.6 cells after the knockdown of ATGL before FA and TM treatment. TM increased hepatic TG accumulation in ATGL KO, but not in WT, mice. Lipogenesis and β‐oxidation were repressed at the gene‐expression level (sterol regulatory element‐binding transcription factor 1c, fatty acid synthase, acetyl coenzyme A carboxylase 2, and carnitine palmitoyltransferase 1 alpha) in both WT and ATGL KO mice. Genes for very‐low‐density lipoprotein (VLDL) synthesis (microsomal triglyceride transfer protein and apolipoprotein B) were down‐regulated by TM in WT and even more in ATGL KO mice, which displayed strongly reduced serum VLDL cholesterol levels. Notably, ER stress markers glucose‐regulated protein, C/EBP homolog protein, spliced X‐box‐binding protein, endoplasmic‐reticulum–localized DnaJ homolog 4, and inflammatory markers Tnfα and iNos were induced exclusively in TM‐treated WT, but not ATGL KO, mice. Total hepatic FA profiling revealed a higher palmitic acid/oleic acid (PA/OA) ratio in WT mice, compared to ATGL KO mice, at baseline. Phosphoinositide‐3‐kinase inhibitor–known to be involved in FA‐derived ER stress and blocked by OA–was increased in TM‐treated WT mice only. In line with this, in vitro OA protected hepatocytes from TM‐induced ER stress. Conclusions: Lack of ATGL may protect from hepatic ER stress through alterations in FA composition. ATGL could constitute a new therapeutic strategy to target ER stress in NAFLD. (HEPATOLOGY 2012;56:270–280 )

Value of tumor size as a prognostic variable in colorectal cancer: a critical reappraisal.

Objectives: Vertical tumor growth, reflected by T classification, represents the most important prognostic variable in colorectal cancer. Our study aimed to investigate the impact of tumor size, particularly the maximum tumor diameter, on outcome of affected patients. Methods: A total of 381 colorectal cancer specimens were re-evaluated. Tumor size and location were extracted from the medical history and were known for 359 patients (94%). Receiver-operator characteristic analysis was applied to identify the optimal (maximum of sum of sensitivity and specificity) cut-off values with respect to prognostic impact. Results: Median tumor size was 4.5 cm (range, 0.6–15). Tumor size exceeding 4.5 cm was observed in 159 patients (44%) and was associated with high T and N classification, UICC stage, and tumor grade. At median follow-up of 45 months (range, 0–180), 141 patients (40%) showed tumor progression. Although 4.5 cm was identified as the optimal cut-off value within the whole group of patients, receiver-operator characteristic analysis restricted to different parts of the large bowel determined 5 cm, 5.3 cm, 3.9 cm, and 3.4 cm as cut-off values with the strongest discriminatory capacity in colon, right-sided colon, left-sided colon, and rectum cancers, respectively. Applying these cut-off values, tumor size was significantly associated with progression-free and cancer-specific survival in univariate and multivariate analyses in colon, yet not in rectum cancers. Conclusions: Tumor size proved to be an independent prognostic parameter for patients with colorectal cancer. Optimal cut-off values vary among different parts of the large bowel. Whereas prognostic significance is strong within the colon, it appears to be of minor value within the rectum.

Characterization of animal models for primary sclerosing cholangitis (PSC)

Primary sclerosing cholangitis (PSC) is a chronic cholangiopathy characterized by biliary fibrosis, development of cholestasis and end stage liver disease, high risk of malignancy, and frequent need for liver transplantation. The poor understanding of its pathogenesis is also reflected in the lack of effective medical treatment. Well-characterized animal models are utterly needed to develop novel pathogenetic concepts and study new treatment strategies. Currently there is no consensus on how to evaluate and characterize potential PSC models, which makes direct comparison of experimental results and effective exchange of study material between research groups difficult. The International Primary Sclerosing Cholangitis Study Group (IPSCSG) has therefore summarized these key issues in a position paper proposing standard requirements for the study of animal models of PSC.

Will we ever model PSC? - "it's hard to be a PSC model!".

Cholangiopathies such as primary sclerosing cholangitis (PSC) represent an important group of liver diseases of the intra- and extrahepatic bile ducts frequently causing end-stage liver disease with significant morbidity and mortality due to limited treatment options. The relatively low incidence of PSC and the difficult accessibility of the human bile duct system for longitudinal studies may represent some of the critical reasons for the lack of profound knowledge in regard to PSC pathophysiology. Therefore, there is an urgent need for reliable, well-defined and easily reproducible animal models to learn more about the pathophysiology of PSC and to test novel treatment modalities. In an ideal world, immunogenetically predisposed animals would develop fibrous-obliterative cholangitis of the intra- and extrahepatic bile ducts in association with inflammation of the gut (especially colitis) in a highly reproducible manner allowing to test new drugs. To date, however, no such animal model is available. We aimed to provide a systematic overview of current available rodent models for sclerosing cholangitis and biliary fibrosis and therefore critically analyzed the characteristics of models for chemically-induced cholangitis, knock-out mouse models with cholangitis, cholangitis induced by infectious agents, models of experimental biliary obstruction, models involving enteric bacterial cell-wall components or colitis, and models of primary biliary epithelial and endothelial cell injury.

Renal cell carcinoma metastatic to the stomach: single‐centre experience and literature review

To investigate the incidence, clinical presentation and therapy of gastric metastases, an uncommon finding, in a large group of patients with renal cell carcinoma (RCC).

Mucinous differentiation in colorectal cancer – indicator of poor prognosis?

Langner C, Harbaum L, Pollheimer M J, Kornprat P, Lindtner R A, Schlemmer A, Vieth M & Rehak P 
(2012) Histopathology 60, 1060–1072