Gülsüm Özlem Elpek

Cellular and molecular mechanisms in the pathogenesis of liver fibrosis: An update

There have been considerable recent advances towards a better understanding of the complex cellular and molecular network underlying liver fibrogenesis. Recent data indicate that the termination of fibrogenic processes and the restoration of deficient fibrolytic pathways may allow the reversal of advanced fibrosis and even cirrhosis. Therefore, efforts have been made to better clarify the cellular and molecular mechanisms that are involved in liver fibrosis. Activation of hepatic stellate cells (HSCs) remains a central event in fibrosis, complemented by other sources of matrix-producing cells, including portal fibroblasts, fibrocytes and bone marrow-derived myofibroblasts. These cells converge in a complex interaction with neighboring cells to provoke scarring in response to persistent injury. Defining the interaction of different cell types, revealing the effects of cytokines on these cells and characterizing the regulatory mechanisms that control gene expression in activated HSCs will enable the discovery of new therapeutic targets. Moreover, the characterization of different pathways associated with different etiologies aid in the development of disease-specific therapies. This article outlines recent advances regarding the cellular and molecular mechanisms involved in liver fibrosis that may be translated into future therapies. The pathogenesis of liver fibrosis associated with alcoholic liver disease, non-alcoholic fatty liver disease and viral hepatitis are also discussed to emphasize the various mechanisms involved in liver fibrosis.

Expression of heat-shock proteins hsp27, hsp70 and hsp90 in malignant epithelial tumour of the ovaries

Recently, considerable attention has been focused on the role of the small heat‐shock protein group hsp27, hsp70 and hsp90 in the clinical outcome of several malignancies. However, conflicting data exist regarding the prognostic role of hsp27 expression in ovarian carcinoma, and the prognostic significance of hsp70 and hsp90 expression still remains unknown in these tumours. The purpose of this study was to investigate immunohistochemically whether hsp27, hsp70 and hsp90 expression was associated with clinicopathological parameters and survival in 52 epithelial ovarian carcinomas. Chi‐square test, Kaplan‐Meier and Cox regression analysis were used for statistical analysis. Among clinicopathological parameters, hsp27, hsp70 and hsp90 expression was only correlated with FIGO stage; hsp70 and hsp90 positivity failed to detect survival. However, the overall survival rate of patients with hsp27 expression was 13%, which was significantly worse than that of patients without hsp27 expression (47%) (p<0.01). The prognosis was also adversely affected by FIGO stage (p<0.01) and presence of ascites (p<0.01). In multivariate analysis, hsp27 expression and FIGO stage were independent prognostic variables. Our results indicate that hsp70 and hsp90 expression had no prognostic relevance in epithelial ovarian carcinomas. However, hsp27 expression and FIGO stage in these tumours could be reliable indicators of prognosis.

Effect of astaxanthin on hepatocellular injury following ischemia/reperfusion

This study investigated the effect of astaxanthin (ASX; 3,3-dihydroxybeta, beta-carotene-4,4-dione), a water-dispersible synthetic carotenoid, on liver ischemia-reperfusion (IR) injury. Astaxanthin (5 mg/kg/day) or olive oil was administered to rats via intragastric intubation for 14 consecutive days before the induction of hepatic IR. On the 15th day, blood vessels supplying the median and left lateral hepatic lobes were occluded with an arterial clamp for 60 min, followed by 60 min reperfusion. At the end of the experimental period, blood samples were obtained from the right ventricule to determine plasma alanine aminotransferase (ALT) and xanthine oxidase (XO) activities and animals were sacrificed to obtain samples of nonischemic and postischemic liver tissue. The effects of ASX on IR injury were evaluated by assessing hepatic ultrastructure via transmission electron microscopy and by histopathological scoring. Hepatic conversion of xanthine dehygrogenase (XDH) to XO, total GSH and protein carbonyl levels were also measured as markers of oxidative stress. Expression of NOS2 was determined by immunohistochemistry and Western blot analysis while nitrate/nitrite levels were measured via spectral analysis. Total histopathological scoring of cellular damage was significantly decreased in hepatic IR injury following ASX treatment. Electron microscopy of postischemic tissue demonstrated parenchymal cell damage, swelling of mitochondria, disarrangement of rough endoplasmatic reticulum which was also partially reduced by ASX treatment. Astaxanthine treatment significantly decreased hepatic conversion of XDH to XO and tissue protein carbonyl levels following IR injury. The current results suggest that the mechanisms of action by which ASX reduces IR damage may include antioxidant protection against oxidative injury.

Hypoxia-inducible factor-1α expression in experimental cirrhosis: correlation with vascular endothelial growth factor expression and angiogenesis†

Angiogenesis progresses together with fibrogenesis during chronic liver injury. Hypoxia‐inducible factor‐1α (HIF‐1α), a master regulator of homeostasis, plays a pivotal role in hypoxia‐induced angiogenesis through its regulation of vascular endothelial growth factor (VEGF). The association between hypoxia, angiogenesis and VEGF expression has been demonstrated in experimental cirrhosis. However, expression of HIF‐1α has yet to be reported. The aim of this study was to investigate the significance of HIF‐1α expression during experimental liver fibrosis and the relationships between HIF‐1α expression, VEGF expression and angiogenesis. Cirrhosis was induced in male Wistar rats by intraperitoneal administration of diethyl nitrosamine (DEN) (100 mg/kg, once a week). The serial sections from liver tissues were stained with anti‐HIF‐1α, anti‐VEGF and anti‐CD34 antibodies before being measured by light microscopy. Our results showed that HIF‐1α expression gradually increases according to the severity of fibrosis (p<0.01). Moreover, its expression was found to be correlated with angiogenesis (r=0.916) and VEGF expression (r=0.969). The present study demonstrates that HIF‐1α might have a role in the development of angiogenesis via regulation of VEGF during experimental liver fibrogenesis and suggests that this factor could be a potential target in the manipulation of angiogenesis in chronic inflammatory diseases of the liver.

Incidental calcifying fibrous tumor of the stomach presenting as a polyp

Calcifying fibrous tumor (CFT) is an uncommon lesion of uncertain cause and pathogenesis that has a unique histological appearance. These lesions are described mainly in the subcutaneous or deep soft tissues, followed by subserosal locations. Intrinsic visceral CFT is extremely rare. Herein is described a rare case of CFT that involved the gastric wall, along with a review of the literature. An incidental small polypoid lesion was excised during urgent surgery for penetrating injury at the lesser curvature in a 25‐year‐old man, previously healthy. The lesion was a well‐demarcated, small (10 mm) tumor that occupied the submucosa. The characteristic histopathological features and the presence of spindle cells that express factor XIIIa allowed a diagnosis of CFT to be made. The present case and the review revealed that, despite their frequent subperitoneal location, intra‐abdominal CFT might present as intrinsic visceral lesions and might be found incidentally. These lesions tend to be smaller when compared to their symptomatic counterparts. The diffuse factor XIIIa expression in CFT might be useful to differentiate this entity from other intra‐abdominal soft‐tissue tumors in problematic cases. Although rarity of intrinsic visceral CFT necessitates new cases to determine their exact biological behavior, the present case highlights their presence in the stomach as a symptomless small polypoid lesion.

Microvessel count, proliferating cell nuclear antigen and Ki-67 indices in gastric adenocarcinoma.

The aim of the present study was to immunohistochemically investigate the prognostic value of neovascularization (expressed as microvessel count-MVC) and tumor cell proliferation (expressed as PCNA labeling index - PLI and Ki-67 labeling index- KLI) in gastric adenocarcinoma. Correlations with clinicopathologic features were also evaluated. Tumor specimens from 74 patients diagnosed as gastric adenocarcinoma were included in this study. For-malin fixed, paraffin embedded tissue sections stained immunohistochemically with F-VIII, PC10 and MIB-1 monoclonal antibodies. By ocular grid subdivided into 100 areas, number of microvessels and PC10, MIB-1 positive and negative cells were counted at x400 magnification. Chi-square test, Kaplan-Meier method and cox regression analysis were used for statistical analysis. The results showed that, MVC and PLI had a significant correlation with invasion and lymph node metastasis. The prognosis was significantly worse in patients with high MVC (>14) and with high PLI (>49%). However any relationship was not observed between KLI (38%) and clinicopathologic parameters, so KLI failed to predict the prognosis. Cox model showed that, MVC and PLI were independent prognostic variables. Ki-67 labeling index in gastric carcinomas has no prognostic relevance. However, the evaluation of microvessel count and proliferating cell nuclear antigen index in gastric carcinomas could be reliable indicators of prognosis.

Androgen Receptor Levels of Oral and Genital Ulcers and Skin Pathergy Test in Patients with Behçet’s Disease

Background: Hormonal factors have long been proposed to play a role in Behçet’s disease (BD). Male sex, systemic onset, HLA-B51 positivity and a younger age of onset in BD are associated with severer disease, and the disease generally runs a milder course in women. Vascular involvement is more common, and the skin pathergy test (SPT) is more strongly positive in men. BD rarely develops before puberty or after the age of 50 years. Clinical manifestations of the disease, with the exception of eye symptoms, tend to improve with time. Therefore, BD may be androgen driven to some degree. Objectives: We aimed to investigate androgen receptor (AR) levels of oral ulcers (OU), genital ulcers (GU) and SPT areas and compared them with those of adjacent normal-appearing skin/mucosa from patients with BD. Methods: Thirty-eight patients with BD (16 female, 22 male; mean ± SD age, 36.45 ± 10.2 years), diagnosed according to the criteria of the International Study Group for Behçet’s Disease, were included in the study with blind histological examination. Biopsies from OU of 10 patients, GU of 11 patients, SPT areas of 17 patients and adjacent (approximately 2 cm distant) normal-appearing skin/mucosa in patients with BD were performed. Nuclear AR levels were studied by an immunohistochemical technique, using monoclonal antibodies. The percentage of positively staining cells was recorded as the AR index (ARI). In addition, the prevalence and the positivity rate of SPT has also been evaluated. Results: ARI values in the lesional and control (non-lesional adjacent) skin/mucosa were found to be 14.5 versus 18% for OU, 28.7 versus 25.5% for GU and 36.3 versus 21.8% (p = 0.068) for SPT areas. The positive SPT areas in male patients showed a higher ARI than those of female patients (43.36 and 23.33%; p = 0.078). The ARI values of SPT areas in male patients but not in female patients were found to be significantly higher as compared with non-lesional skin (21.63%; p = 0.039). The SPT positivity was also more common in male patients compared with female patients (86.4% and 62.5%), although the difference was not significant (p = 0.88). SPT have been found to be more strongly positive among the males (4.63 ± 3.3) compared with female patients (3.18 ± 1.9), and the difference was statistically significant (p = 0.022). Conclusions: Our findings indicate that androgens seem to play a role both in the formation and increased positivity of the SPT areas in male patients with BD.

Measurement of intracellular biomolecular oxidation in liver ischemia–reperfusion injury via immuno-spin trapping

Hepatic ischemia-reperfusion (I/R) can lead to liver failure in association with remote organ damage, both of which have significant rates of morbidity and mortality. In this study, novel spin trapping and histopathological techniques have been used to investigate in vivo free radical formation in a rat model of warm liver I/R injury. 5,5-Dimethyl-1-pyrroline N-oxide (DMPO) was administered to rats via intraperitoneal injection at a single dose of 1.5g of pure DMPO/kg body wt 2h before the initiation of liver ischemia. Blood vessels supplying the median and left lateral hepatic lobes were occluded with an arterial clamp for 60min, followed by 60min reperfusion. The effects of DMPO on I/R injury were evaluated by assessing the hepatic ultrastructure via transmission electron microscopy and by histopathological scoring. Immunoelectron microscopy was performed to determine the cellular localization of DMPO nitrone adducts. Levels of nitrone adducts were also measured to determine in situ scavenging of protein and DNA radicals. Total histopathological scoring of cellular damage was significantly decreased in hepatic I/R injury after DMPO treatment. DMPO treatment significantly decreased the hepatic conversion of xanthine oxidase and 4-hydroxynonenal formation in I/R injury compared to the untreated I/R group. The distribution of gold-nanoparticle-labeled DMPO nitrone adducts was observed in mitochondria, cytoplasm, and nucleus of hepatocytes. The formation of protein- and DNA-nitrone adducts was increased in DMPO-treated I/R livers compared to DMPO controls, indicating increased in situ protein and DNA radical formation and scavenging by DMPO. These results suggest that DMPO reduces I/R damage via protection against oxidative injury.

Clinicopathologic evaluation of CDw75 antigen expression in patients with gastric carcinoma.

Situated on mature B lymphocytes, CDw75 antigen is a sialylated carbohydrate epitope generated by the enzyme β‐galactosyl α‐2,6‐sialyltransferase. Although CDw75 antigen expression was found to be correlated with aggressive behaviour of tumour cells in gastric adenocarcinomas, its prognostic role still remains unknown. The objective of this study was to determine the value of CDw75 antigen expression as a marker of the metastatic potential and prognosis of gastric adenocarcinomas. CDw75 antigen expression was evaluated immunohistochemically in 64 tumours and their nodal metastases. The correlation was analysed between CDw75 antigen expression and selected clinicopathological variables, including surrival.

Clinicopathologic evaluation of CDw75 antigen expression in colorectal adenocarcinomas

CDw75, a B lymphocyte surface antigen, is a sialylated carbohydrate epitope, which is generated by the enzyme β galactosyl α2,6 sialyltransferase (Sia-T1). In colon carcinomas, although higher levels of Sia-T1 has been described and found to be correlated with metastatic potential of tumor cells, the expression of CDw75 antigen still remains unknown. To address this issue, we investigated immunohistochemically CDw75 antigen expression in 195 colorectal adenocarcinomas and their nodal metastases. The correlation between CDw75 antigen expression with selected clinicopathologic variables was analyzed by using Chi-square and Fisher’s exact tests. Positive staining was observed in 101 cases. Non-neoplastic mucosa was negative consistently. The frequency of positivity was decreased according to the degree of differentiation (p<0.001). Antigen expression was found to be associated with deeper penetration (p<0.006), positive lymph nodes (p<0.001), distant metastases (p<0.006) and advanced stage (p<0.001). Same relationships were detected in well and moderately differentiated tumors when CDw75 immunoreactivity was evaluated in each histologie grade separately. Our findings indicate that CDw75 antigen expression may be a good indicator of the biological aggressiveness of colorectal adenocarcinomas especially in tumors with well and moderately differentiated morphology.