Sara Morgenstern

Variable response to probiotics in two models of experimental colitis in rats

Background and AimClinical and experimental data suggest an important role for intestinal microflora in the pathogenesis of inflammatory bowel disease, and probiotics have been shown to ameliorate pouchitis. We evaluated the effect of different preparations of probiotic bacteria on experimental colitis in rats. MethodsRats were treated daily intragastrically with two probiotic preparations, VSL#3 or Lactobacillus strain GG (LGG), 7 days before induction of colitis and for another week thereafter. Colitis was induced by intracolonic administration of either dinitrobenzene sulfonic acid (DNBS) or iodoacetamide. Rats were killed 7 days after induction of colitis, the colon isolated, washed, weighed, lesion area measured, and mucosa processed for determination of myeloperoxidase (MPO) and nitric oxide synthase (NOS) activities and prostaglandin E2 (PGE2) generation. ResultsIn rats cotreated with VSL#3 or LGG and iodoacetamide, there was a significant decrease in the lesion area, 98 ± 37 mm2 and 142 ± 43 mm2, respectively, as compared with 342 ± 66 mm2 in the control group. Colonic wet weight significantly decreased to 1.3 ± 0.1 g/10 cm and 1.4 ± 0.1 g/10 cm, respectively, as compared with 1.7 ± 0.1 g/10 cm. There was also a significant decrease in PGE2 generation, MPO, and NOS activities in the VSL#3 and LGG treatment groups. Presence of VSL#3 bacteria in the rats colon was confirmed by culture and polymerase chain reaction (PCR) amplification. Neither probiotic preparation had an effect on the extent of colonic damage in DNBS-induced colitis. ConclusionBoth VSL#3 and LGG significantly ameliorated colitis induced by the sulfhydryl-blocker iodoacetamide, but had no effect on the immune-mediated DNBS-induced colitis. The results suggest a possible role for sulfhydryl compounds in the protective effect of probiotic bacteria, and support their use in patients with inflammatory bowel disease.

A Diagnostic Assay Based on MicroRNA Expression Accurately Identifies Malignant Pleural Mesothelioma

The definitive identification of malignant pleural mesothelioma (MPM) has significant clinical implications, yet other malignancies often involve the lung pleura, confounding the diagnosis of MPM. In the absence of accurate markers, MPM can be difficult to distinguish from peripheral lung adenocarcinoma and metastatic epithelial cancers. MicroRNA expression is tissue-specific and highly informative for identifying tumor origin. We identified microRNA biomarkers for the differential diagnosis of MPM and developed a standardized microRNA-based assay. Formalin-fixed, paraffin-embedded samples of 33 MPM and 210 carcinomas were used for assay development. Using microarrays, we identified microRNAs differentially expressed between MPM and various carcinomas. Hsa-miR-193-3p was overexpressed in MPM, while hsa-miR-200c and hsa-miR-192 were overexpressed in peripheral lung adenocarcinoma and carcinomas that frequently metastasize to lung pleura. We developed a standardized diagnostic assay based on the expression of these microRNAs. The assay reached a sensitivity of 100% and a specificity of 94% in a blinded validation set of 68 samples from the lung and pleura. This diagnostic assay can provide a useful tool in the differential diagnosis of MPM from other malignancies in the pleura.

MicroRNAs as a potential prognostic factor in gastric cancer

AIM To compare the microRNA (miR) profiles in the primary tumor of patients with recurrent and non-recurrent gastric cancer. METHODS The study group included 45 patients who underwent curative gastrectomies from 1995 to 2005 without adjuvant or neoadjuvant therapy and for whom adequate tumor content was available. Total RNA was extracted from formalin-fixed paraffin-embedded tumor samples, preserving the small RNA fraction. Initial profiling using miR microarrays was performed to identify potential biomarkers of recurrence after resection. The expression of the differential miRs was later verified by quantitative real-time polymerase chain reaction (qRT-PCR). Findings were compared between patients who had a recurrence within 36 mo of surgery (bad-prognosis group, n = 14, 31%) and those who did not (good-prognosis group, n = 31, 69%). RESULTS Three miRs, miR-451, miR-199a-3p and miR-195 were found to be differentially expressed in tumors from patients with good prognosis vs patients with bad prognosis (P < 0.0002, 0.0027 and 0.0046 respectively). High expression of each miR was associated with poorer prognosis for both recurrence and survival. Using miR-451, the positive predictive value for non-recurrence was 100% (13/13). The expression of the differential miRs was verified by qRT-PCR, showing high correlation to the microarray data and similar separation into prognosis groups. CONCLUSION This study identified three miRs, miR-451, miR-199a-3p and miR-195 to be predictive of recurrence of gastric cancer. Of these, miR-451 had the strongest prognostic impact.

MONOCLONAL ANTI-ENDOTHELIAL CELL ANTIBODIES FROM A PATIENT WITH TAKAYASU ARTERITIS ACTIVATE ENDOTHELIAL CELLS FROM LARGE VESSELS

OBJECTIVE To create monoclonal anti-endothelial cell antibodies (mAECA) from a patient with Takayasu arteritis to evaluate their ability to activate human umbilical vein endothelial cells (HUVEC), and to characterize the mechanism of EC activation. METHODS A panel of mAECA was generated from peripheral blood lymphocytes of a patient with Takayasu arteritis, using Epstein-Barr virus transformation. Activity against macrovascular EC (HUVEC) and microvascular EC (human bone marrow EC immortalized by SV40) antigens was detected by enzyme-linked immunosorbent assay. Inhibition studies were used to select the monoclonal antibodies (mAECA) which share the same EC epitope binding specificity as the total IgG-AECA from the Takayasu arteritis patient. The binding of the mAECA to human aortic EC was studied by immunohistochemistry. The secretion levels of interleukin-6 (IL-6) and von Willebrand factor (vWF) were determined, to serve as markers for EC activation. The activated EC were examined for the adherence of a monocytic cell line (U937), as well as for expression of vascular cell adhesion molecule 1, intercellular adhesion molecule 1, and E-selectin. In addition, nuclear extracts of the mAECA-treated EC were analyzed for the induction of translocation of nuclear factor kappaB (NF-kappaB), using a specific NF-kappaB oligoprobe in an electrophoretic mobility shift assay. RESULTS Six mAECA were selected, the mixture of which produced 100% inhibition of binding of the original IgG (from the patient with Takayasu arteritis) to HUVEC. All mAECA possessed high activity against macrovascular EC, but none had significant antimicrovascular EC activity. The mAECA, but not normal human IgG, had anti-human aortic EC activity. Four of the 6 mAECA activated EC, manifested by increased IL-6 and vWF secretion. The 4 mAECA induced EC expression of adhesion molecules and increased adhesion of U937 monocytic cells to EC. In addition, these mAECA stimulated the nuclear translocation of the NF-kappaB transcription factor. CONCLUSION Our findings suggest that AECA may directly stimulate EC in Takayasu arteritis through elevation of adhesion molecule expression associated with NF-kappaB activation and adhesion of monocytes, and may therefore play a pathogenic role in the development of the vasculopathy in Takayasu arteritis.

Diagnostic Performance of a Novel Device for Real-Time Margin Assessment in Lumpectomy Specimens

BACKGROUND Margin status in breast lumpectomy procedures is a prognostic factor for local recurrence and the need to obtain clear margins is often a cause for repeated surgical procedures. A recently developed device for real-time intraoperative margin assessment (MarginProbe; Dune Medical Devices, Caesarea, Israel), was clinically tested. The work presented here looks at the diagnostic performance of the device. METHODS The device was applied to freshly excised lumpectomy and mastectomy specimens at specific tissue measurement sites. These measurement sites were accurately marked, cut out, and sent for histopathologic analysis. Device readings (positive or negative) were compared with histology findings (namely malignant, containing any microscopically detected tumor, or nonmalignant) on a per measurement site basis. The sensitivity and specificity of the device was computed for the full dataset and for additional relevant subgroups. RESULTS A total of 869 tissue measurement sites were obtained from 76 patients, 753 were analyzed, of which 165 were cancerous and 588 were nonmalignant. Device performance on relatively homogeneous sites was: sensitivity 1.00 (95% CI: 0.85-1), specificity 0.87 (95% CI: 0.83-0.90). Performance for the full dataset was: sensitivity 0.70 (95% CI: 0.63-0.77), specificity 0.70 (95% CI: 0.67-0.74). Device sensitivity was estimated to change from 56% to 97% as the cancer feature size increased from 0.7 mm to 6.6 mm. Detection rate of samples containing pure DCIS clusters was not different from rates of samples containing IDC. CONCLUSIONS The device has high sensitivity and specificity in distinguishing between normal and cancer tissue even down to small cancer features.

Tumor microRNA-29a expression and the risk of recurrence in stage II colon cancer

There is emerging evidence for the prognostic role of various microRNA (miRNA) molecules in colon cancer. The aim of this study was therefore to compare the miRNA profiles in the primary tumor of patients with recurrent and non-recurrent colon cancer. The study population included 110 patients, 51 (46%) with stage I and 59 (54%) with stage II disease, who underwent curative colectomies between 1995 and 2005 without adjuvant therapy and for whom reliable miRNA expression data were available. RNA was extracted from formalin-fixed paraffin-embedded (FFPE) tumor samples. Initial profiling, using microarrays, was done in order to identify potential biomarkers of recurrence. The miRNA expression was later verified by quantitative real-time polymerase chain reaction (qRT-PCR). Findings were compared between patients who had a recurrence within 36 months of surgery (bad prognosis group, n=23, 21%) and those who did not (good prognosis group, n=87, 79%) in the entire group and within each stage. The results showed that in stage I, none of the 903 miRNAs tested showed differential expression between patients with good prognosis compared with those with poor prognosis. In contrast, in stage II, one miRNA, miR-29a, showed a clear differential expression between the groups (p=0.028). High expression of miR-29a was associated with a longer disease-free survival (DFS), on both univariate and multivariate analyses. Using miR-29a, the positive predictive value for non-recurrence was 94% (2 recurrences among 31 patients). The differential expression of miR-29a was verified by qRT-PCR, showing a similar impact of this miR on DFS. In conclusion, this study demonstrated a significant impact of miR-29a on the risk of recurrence in patients with stage II but not in patients with stage I colon cancer. Based on these results, a validation study is planned.

Does Helicobacter pylori affect gastric mucin expression? Relationship between gastric antral mucin expression and H. pylori colonization

BACKGROUND/OBJECTIVE: Helicobacter pylori colonizes the gastric mucous gel layer, the surface epithelium and glands. It has been shown that H. pylori infection causes aberrant expression of gastric mucins MUC 5 and MUC 6. This study aimed to determine the distribution of MUC 5 and MUC 6 in the gastric antrum of dyspeptic patients, and to investigate changes in this pattern in the presence of H. pylori and after successful eradication. MATERIALS AND METHODS: Gastric antrum biopsy specimens were examined by immunohistochemistry for mucin gene (MUC 5 and MUC 6) expression. Polyclonal antibodies were used to detect amino acid tandem repeats of each protein. A scoring system (0-3) was used to assess staining intensity at three sites: foveola, mucous neck cells and glands. H. pylori status was determined by histology and rapid urease test, and considered positive or negative when both tests were positive or negative, respectively. The study included 49 patients positive for H. pylori, in 36 of whom successful eradication was performed, and 11 H. pylori-negative patients. RESULTS: There was a gradient of MUC 5 expression, higher to lower, from the surface to the glands, which was more pronounced before eradication. Increased MUC 5 synthesis in the mucous neck cells and in the glands was found after H. pylori eradication (P = 0.016). MUC 6 was synthesized in the glands more than in the mucous neck cells or foveola. MUC 6 was also secreted into the lumen and probably comprised the superficial part of the unstirred mucous layer. CONCLUSION: The change in MUC 5 synthesis may reflect H. pylori colonization.

HLA-DR and β2 microglobulin expression in medullary and atypical medullary carcinoma of the breast: histopathologically similar but biologically distinct entities

Aims—To examine the expression of HLA-DR and β2 microglobulin in medullary carcinoma and atypical medullary carcinoma of the breast to determine if the effective presentation of tumour antigens to the immune system can differentiate between these two histopathologically similar entities. Methods—Expression of HLA-DR and β2 microglobulin was examined by immunohistochemical methods in five samples of medullary carcinoma of the breast, which has a relatively favourable prognosis, six samples of atypical medullary carcinoma of the breast, which has a prognosis closer to that of regular invasive duct carcinoma, and 20 samples of invasive duct carcinomas, 10 with an accompanying lymphocytic infiltrate. Results—A positive and significant correlation was found between tumour type and both HLA-DR and β2 microglobulin expression. Expression was most prominent in medullary carcinoma, followed by atypical medullary carcinoma and invasive duct carcinoma with and without lymphocytic infiltrates. The mean intensity and percentage of HLA-DR tumour immunostaining were significantly higher in medullary carcinoma than in the other three tumour groups, as was the mean intensity of β2 microglobulin immunostaining. Mean percentage of β2 microglobulin immunostaining was significantly higher in medullary carcinoma than in invasive duct carcinoma without lymphocytic infiltrates, and showed a trend to increase from invasive duct carcinoma with lymphocytic infiltrates to atypical medullary carcinoma and medullary carcinoma. Conclusions—Medullary carcinoma and atypical medullary carcinoma of the breast differ in their expression of HLA-DR and β2 microglobulin. The relatively favourable prognosis of medullary carcinoma of the breast may be related to effective tumour antigen presentation to the immune system through MHC-I and MHC-II expression. Immunotherapy aimed at MHC-I and MHC-II induction might have a beneficial effect in breast cancer.

Gallbladder inflammation is associated with increase in mucin expression and pigmented stone formation

Mucin is a high molecular weight glycoprotein that plays an important role in protecting the gallbladder epithelium from the detergent effect of bile. However, it also participates in gallstone formation. There is little information about a possible relationship between gallbladder inflammation and mucin expression or gallbladder stones’ characteristics. The aims of this study were to investigate stone characteristics and patterns of mucin expression in the gallbladder epithelium and bile of gallstone patients, in relation to inflammation. Gallbladder bile and tissue samples from 21 patients were obtained at surgery. Mucin content was evaluated by gel filtration on a Sepharose CL-4B column. Dot blot for bile mucin apoproteins and immunohistochemistry staining for gallbladder mucosal mucin apoproteins were performed with antibodies to MUC2, MUC3, MUC5AC, MUC5B and MUC6. Staining intensity score (0–3) was used for assessment of antigen expression and the level of inflammation. Gallstone cholesterol content was determined in 16 patients. MUC 5AC and MUC 5B were demonstrated in 95.4 and 100% of gallbladder bile samples, respectively. Immunohistochemistry staining with antibodies to MUC 2, MUC 3, MUC 5AC, MUC 5B and MUC 6 were positive in 0, 100, 85.7, 100 and 95.4% of the gallbladder mucosal samples, respectively. Pigmented brown stones were associated with a higher level of gallbladder inflammation. Mucin species expressed in gallbladder epithelium are MUC3, MUC5AC, MUC5B and MUC6. MUC5AC and MUC5B are secreted into bile. Inflammation of the gallbladder is accompanied by a higher level of MUC5AC expression and is associated with pigmented brown stones.

Upper and lower gastrointestinal findings in PTEN mutation-positive Cowden syndrome patients participating in an active surveillance program

OBJECTIVES:Cowden syndrome (CS), associated with germline PTEN mutations, is an autosomal-dominant disorder with increased frequencies of thyroid and breast cancers. Recent reports document the occurrence of gastrointestinal (GI) polyps and increased risk of colon cancer in PTEN mutation carriers. Studies to date, however, have not been based on mutation carriers undergoing active, systematic, routine-interval GI surveillance. Our objective is to document the upper and lower GI findings in CS patients undergoing such an active GI surveillance program.METHODS:In a 5-year period, 3,000 consecutive patients were referred to our high-risk GI cancer clinic for various reasons. Of these 3,000, 10 met full-blown clinical criteria for the diagnosis of CS. Individuals with identified PTEN mutations underwent annual upper and lower endoscopy surveillance programs using dual white light and narrow-band imaging. All biopsies including archived materials were reviewed by a single dedicated GI pathologist.RESULTS:Ten PTEN mutation carriers from different ethnic backgrounds were invited and all participated in the active GI surveillance program. Eight patients had colonic polyps, mostly hyperplastic (eight patients) and hamartomatous (five patients), but also adenomatous (three patients), ganglioneuromatous (three patients), and juvenile polyps (two patients). One patient (10%) had an early-onset rectal cancer (aged 44 years), which was null for PTEN expression on immunohistochemistry. All patients had gastric polyps and nine (90%) had duodenal polyps, mostly hyperplastic and hamartomatous. Additional three patients (30%) had adenomatous duodenal polyps.CONCLUSIONS:PTEN mutation–positive CS patients have a higher frequency of upper GI polyps than previously believed. They appear prone to develop adenomatous upper and lower tract dysplastic polyps and cancer. Thus, the polyps encountered during upper or lower endoscopy in these patients should not be automatically considered innocent hamartomas without malignant potential. Active surveillance programs in specialized centers should be considered in these patients.