Bernd Lahrmann

Postischemic brain infiltration of leukocyte subpopulations differs among murine permanent and transient focal cerebral ischemia models.

Cellular and humoral inflammations play important roles in ischemic brain injury. The effectiveness of immunomodulatory therapies may critically depend on the chosen experimental model. Our purpose was to compare the post‐ischemic neuroinflammation among murine permanent and transient middle cerebral artery occlusion (MCAO) models. Permanent MCAO was induced by transtemporal electrocoagulation and 30 minutes or 90 minutes transient MCAO was induced by intraluminal filament in C57BL/6 mice. Infiltration of leukocyte subpopulations was quantified by immunohistochemistry and fluorescence‐activated cell sorting. Cerebral cytokine and adhesion molecule expression was measured by real‐time polymerase chain reaction (RT‐PCR). Neutrophil infiltration was noted at 24 h after transient MCAO, but did not further increase until 5 days in the permanent MCAO model. Few T cells were observed in both MCAO models at 24 h, but permanent MCAO demonstrated much more infiltrating T cells at 5 days. Pronounced microglial activation was evident at 24 h and 5 days after permanent but not after transient MCAO. The number of invading NK cells and expression of MHCII on CD11b+ cells did not differ among the three groups. Five days after MCAO, the expression of IL‐1, TNF‐α and IFN‐γ and of the adhesion molecules ICAM‐1 and VCAM‐1 was significantly higher in the permanent than in the transient MCAO groups. Cellular and humoral inflammation differs substantially among commonly used MCAO models. Neuroinflammation is more pronounced after permanent electrocoagulatory MCAO compared with 30 minutes and 90 minutes filament‐MCAO.

HPV-related methylation signature predicts survival in oropharyngeal squamous cell carcinomas

High-risk types of human papilloma virus (HPV) are increasingly associated with oropharyngeal squamous cell carcinoma (OPSCC). Strikingly, patients with HPV-positive OPSCC are highly curable with ionizing radiation and have better survival compared with HPV-negative patients, but the underlying molecular mechanisms remain poorly understood. We applied an array-based approach to monitor global changes in CpG island hypermethylation between HPV-negative and HPV-positive OPSCCs and identified a specific pattern of differentially methylated regions that critically depends on the presence of viral transcripts. HPV-related alterations were confirmed for the majority of candidate gene promoters by mass spectrometric, quantitative methylation analysis. There was a significant inverse correlation between promoter hypermethylation of ALDH1A2, OSR2, GATA4, GRIA4, and IRX4 and transcript levels. Interestingly, Kaplan-Meier analysis revealed that a combined promoter methylation pattern of low methylation levels in ALDH1A2 and OSR2 promoters and high methylation levels in GATA4, GRIA4, and IRX4 promoters was significantly correlated with improved survival in 3 independent patient cohorts. ALDH1A2 protein levels, determined by immunohistochemistry on tissue microarrays, confirmed the association with clinical outcome. In summary, our study highlights specific alterations in global gene promoter methylation in HPV-driven OPSCCs and identifies a signature that predicts the clinical outcome in OPSCCs.

Pathogenic role of the eight probably/possibly carcinogenic HPV types 26, 53, 66, 67, 68, 70, 73 and 82 in cervical cancer

Eight HPV types (HPV26, 53, 66, 67, 68, 70, 73 and 82) that are phylogenetically closely related to 12 WHO‐defined high‐risk (HR) HPV have been rarely but consistently identified as single HPV infections in about 3% of cervical cancer (CxCa) tissues. Due to lack of biological data, these types are referred to as probable/possible (p) HR‐HPV. To analyse their biological activity in direct comparison to HR‐HPV types, we selected 55 formalin‐fixed, paraffin‐embedded (FFPE) CxCa tissues harbouring single pHR‐HPV infections (2–13 cases per type) and 266 tissues harbouring single HR‐HPV (7–40 cases per type) from a worldwide, retrospective, cross‐sectional study. Single HPV infection was verified by two genotyping methods. Presence of type‐specific spliced E6*I mRNA transcripts and expression of cellular proteins indicative of HPV transformation were assessed in all cases. In 55 CxCa tissues with pHR‐HPV, E6*I mRNA expression was 100%; high p16INK4a, 98%; low pRb, 96%; low CyD1, 93%; and low p53, 84%. Compared to HPV16 tissues as a reference, individual frequencies of these five markers did not differ significantly, either for any of the eight pHR‐HPV and the 11 other HR types individually or for the groups of pHR and HR types without HPV16. We conclude that the eight pHR‐HPV types, when present as a single infection in CxCa, are biologically active and affect the same cellular pathways as any of the fully recognized carcinogenic HR‐HPV types. Therefore we have provided molecular evidence of carcinogenicity for types currently classified as probably/possibly carcinogenic. Although this evidence is crucial for HPV‐type carcinogenicity classification, per se it is not sufficient for inclusion of these HPV types into population‐wide primary and secondary prevention programmes. Such decisions have to include careful estimation of effectiveness and cost–benefit analyses. Copyright

Identification of oropharyngeal squamous cell carcinomas with active HPV16 involvement by immunohistochemical analysis of the retinoblastoma protein pathway.

Viral oncogene RNA expression is regarded as reliable biomarker to identify oropharyngeal squamous cell carcinomas (OPSCC) with active HPV16 involvement. This study addressed whether the expression profile of the cellular proteins p16INK4a, pRb, Cyclin D1 and p53 provide surrogate marker combinations that identify OPSCC with active HPV16 in situations where only formalin‐fixed biopsies are available. Protein expression was analyzed by immunohistochemistry on tissue microarrays created from 188 OPSCC of which the HPV16 DNA and RNA status had been established previously from snap‐frozen biopsies. Associations of single markers and of marker combinations with HPV16 DNA, viral RNA expression patterns and overall survival as primary end point were evaluated by statistical analysis. Most tumors with active HPV16 involvement (RNA+ group; n = 40) showed a specific protein pattern, that is, high p16INK4a (80%), low pRb (85%), low Cyclin D1 (95%) and normal p53 (73%). This pattern was significantly different from the pattern observed in HPV DNA‐negative tumors (HPV– group) and in HPV16 DNA‐positive tumors lacking viral RNA expression patterns (RNA– group). The combination of high p16INK4a and low pRb levels was distinctly superior to p16INK4a alone; it was strongly associated with RNA+ tumors (OR 41.4, 95%CI 10.7–162.5), with improved survival (HR 0.37, 95%CI 0.2–0.8) and had best predictive values (78% sensitivity, 93% specificity, 78% PPV, 93% NPV). In conclusion, if only formalin‐fixed biopsy material is available, the marker combination high p16INK4a/low pRb is well suited to identify OPSCC with biologically active HPV16 which represent a distinct OPSCC entity with improved prognosis.

Expression analysis of aldehyde dehydrogenase 1A1 (ALDH1A1) in colon and rectal cancer in association with prognosis and response to chemotherapy

BackgroundAldehyde dehydrogenase 1A1 (ALDH1A1) has been described as a cancer stem cell marker and as a regulator of cellular chemoresistance. Therefore, ALDH1A1 has been suggested as potential biomarker to stratify patients into different risk categories for a “personalized” therapy approach. We have investigated the prognostic role of ALDH1A1 in primary colorectal cancer and its value in predicting response to chemotherapy in metastatic colorectal cancer.MethodsImmunostaining against ALDH1A1 was performed on a paraffin-embedded tissue microarray including 659 primary colon cancer samples and 338 rectal cancer samples. Likewise, tissue of 44 palliatively resected colorectal liver metastases on whole-mount tissue slides was immunostained against ALDH1A1. Cytoplasmic, nuclear, and stromal expression of ALDH1A1 was assessed and merged with histopathological and clinical data.ResultsUnivariate and multivariate analysis revealed that cytoplasmic and stromal expression of ALDH1A1 is not significantly associated with prognosis either in colon or in rectal cancer. Furthermore, cytoplasmic expression of ALDH1A1 does not predict response to palliative chemotherapy in patients with metastatic diseases. Intriguingly, as a novel finding, nuclear expression of ALDH1A1 was observed in a small subgroup of patients with colon cancer and rectal cancer. In colon cancer, nuclear expression was significantly associated with shortened overall survival by univariate and multivariate analysis.ConclusionsImmunohistochemical expression analysis of ALDH1A1 in colon cancer is useful for the detection of nuclear expression in a small subpopulation of patients and is associated with shorter survival. Cytoplasmic expression fails to be of clinical relevance as prognostic or predictive marker in colorectal cancer.

A virtual microscopy system to scan, evaluate and archive biomarker enhanced cervical cytology slides.

Background: Although cytological screening for cervical precancers has led to a reduction of cervical cancer incidence worldwide it is a subjective and variable method with low single-test sensitivity. New biomarkers like p16 that specifically highlight abnormal cervical cells can improve cytology performance. Virtual microscopy offers an ideal platform for assisted evaluation and archiving of biomarker-stained slides. Methods: We first performed a quantitative analysis of p16-stained slides digitized with the Hamamatsu NDP slide scanner. From the results an automated algorithm was created to reliably detect cells, nuclei and p16-stained cells. The algorithms performance was evaluated on two complete slides and tiles from 52 independent slides (11,628, 4094 and 25,619 cells/clusters, respectively). Results: We achieved excellent performance to discriminate unstained cells from nuclei and biomarker-stained cells. The automated algorithm showed a high overall and positive agreement (99.0–99.7% and 70.9–83.4%, respectively) with the gold standard and had a very high sensitivity (89.1–100.0%) and specificity (98.9–100.0%) to detect biomarker-stained cells. Conclusions: We implemented a virtual microscopy system allowing highly efficient automated prescreening and archiving of biomarker-stained slides. Based on the initial results, we will evaluate the performance of our system in large epidemiologic studies against disease endpoints.

Semantic Focusing Allows Fully Automated Single-Layer Slide Scanning of Cervical Cytology Slides

Liquid-based cytology (LBC) in conjunction with Whole-Slide Imaging (WSI) enables the objective and sensitive and quantitative evaluation of biomarkers in cytology. However, the complex three-dimensional distribution of cells on LBC slides requires manual focusing, long scanning-times, and multi-layer scanning. Here, we present a solution that overcomes these limitations in two steps: first, we make sure that focus points are only set on cells. Secondly, we check the total slide focus quality. From a first analysis we detected that superficial dust can be separated from the cell layer (thin layer of cells on the glass slide) itself. Then we analyzed 2,295 individual focus points from 51 LBC slides stained for p16 and Ki67. Using the number of edges in a focus point image, specific color values and size-inclusion filters, focus points detecting cells could be distinguished from focus points on artifacts (accuracy 98.6%). Sharpness as total focus quality of a virtual LBC slide is computed from 5 sharpness features. We trained a multi-parameter SVM classifier on 1,600 images. On an independent validation set of 3,232 cell images we achieved an accuracy of 94.8% for classifying images as focused. Our results show that single-layer scanning of LBC slides is possible and how it can be achieved. We assembled focus point analysis and sharpness classification into a fully automatic, iterative workflow, free of user intervention, which performs repetitive slide scanning as necessary. On 400 LBC slides we achieved a scanning-time of 13.9±10.1 min with 29.1±15.5 focus points. In summary, the integration of semantic focus information into whole-slide imaging allows automatic high-quality imaging of LBC slides and subsequent biomarker analysis.

A comparison of dacron versus Flocked nylon swabs for anal cytology specimen collection.

Objectives: We compared the performance of commonly used Dacron versus flocked nylon swabs for anal cytology. Study Design: From 23 HIV-positive men screened at Kaiser Permanente San Francisco (San Francisco, Calif., USA), 2 anal specimens were collected, 1 with each swab in random order, and placed into liquid cytology medium. Specimens were tested for cellularity by quantifying a genomic DNA (erv-3). The number of cells was assessed from prepared slides by automated image analysis. Performance was compared between swabs using 2-sample t tests and standard crossover trial analysis methods accounting for period effect. Results: Flocked swabs collected slightly more erv-3 cells than Dacron for the first sample although not significantly (p = 0.18) and a similar number of erv-3 cells for the second sample (p = 0.85). Flocked swabs collected slightly more cells per slide than the Dacron swabs at both time periods although this was only significant in the second time period (p = 0.42 and 0.03 for first and second periods, respectively). In crossover trial analysis, flocked swabs outperformed Dacron for cell count per slide based on slide imaging (p = 0.03), but Dacron and flocked swabs performed similarly based on erv-3 quantification (p = 0.14). Conclusions: Further studies should determine whether flocked swabs increase the representation of diagnostically important cells compared to Dacron.

Mismatch repair-deficient crypt foci in lynch syndrome-molecular alterations and association with clinical parameters

Lynch syndrome is caused by germline mutations of DNA mismatch repair (MMR) genes, most frequently MLH1 and MSH2. Recently, MMR-deficient crypt foci (MMR-DCF) have been identified as a novel lesion which occurs at high frequency in the intestinal mucosa from Lynch syndrome mutation carriers, but very rarely progress to cancer. To shed light on molecular alterations and clinical associations of MMR-DCF, we systematically searched the intestinal mucosa from Lynch syndrome patients for MMR-DCF by immunohistochemistry. The identified lesions were characterised for alterations in microsatellite-bearing genes with proven or suspected role in malignant transformation. We demonstrate that the prevalence of MMR-DCF (mean 0.84 MMR-DCF per 1 cm2 mucosa in the colorectum of Lynch syndrome patients) was significantly associated with patients’ age, but not with patients’ gender. No MMR-DCF were detectable in the mucosa of patients with sporadic MSI-H colorectal cancer (n = 12). Microsatellite instability of at least one tested marker was detected in 89% of the MMR-DCF examined, indicating an immediate onset of microsatellite instability after MMR gene inactivation. Coding microsatellite mutations were most frequent in the genes HT001 (ASTE1) with 33%, followed by AIM2 (17%) and BAX (10%). Though MMR deficiency alone appears to be insufficient for malignant transformation, it leads to measurable microsatellite instability even in single MMR-deficient crypts. Our data indicate for the first time that the frequency of MMR-DCF increases with patients’ age. Similar patterns of coding microsatellite instability in MMR-DCF and MMR-deficient cancers suggest that certain combinations of coding microsatellite mutations, including mutations of the HT001, AIM2 and BAX gene, may contribute to the progression of MMR-deficient lesions into MMR-deficient cancers.

Hepatic metastases of colorectal cancer are rather homogeneous but differ from primary lesions in terms of immune cell infiltration

The immune system plays an important role in shaping the clinical course of colorectal cancer (CRC). However, it is still unclear how the immune infiltrates of primary CRC lesions and distant metastases by immune effector cells are related to each other. To address this issue, we quantified CD3+, CD8+ and granzyme B+ lymphocytes in primary CRC samples and corresponding liver metastases. This analysis showed that the prognostic predictions that can be drawn from the infiltration of immune cells in primary CRCs and their metastases are heterogeneous. To investigate whether such heterogeneity would also be observed within CRC hepatic metastases, the density of the immune infiltrate and cytokine production were assessed in opposite sides of the same metastatic lesion. In addition, tumor-infiltrating lymphocytes were assessed in sequential sections of the same metastatic lesion, with a spacing of 30 μm. In summary, consistent cell counts and cytokine levels were detected within the same lesion. The study of a case of synchronous metastases, however, suggested that different metastatic lesions within the same patient may be heterogeneous, perhaps indicating a major impact for local causes on tumor infiltration by immune cells. In summary, our study demonstrates a consistent degree of heterogeneity between primary tumors and hepatic metastases but an excellent intra-lesional homogeneity. These findings may be of key importance for patient stratification and the development of personalized strategies against CRC.