Helen P. Cathro

Compartmentalization of neutrophils in the kidney and lung following acute ischemic kidney injury

During renal ischemia-reperfusion, local and distant tissue injury is caused by an influx of neutrophils into the affected tissues. Here we measured the kinetics of margination and transmigration of neutrophils in vivo in the kidney and lungs following renal ischemia-reperfusion. After bilateral renal injury, kidney neutrophil content increased threefold at 24 h. The neutrophils were found primarily in the interstitium and to a lesser degree marginated to the vascular endothelium. These interstitial neutrophils had significantly lower levels of intracellular IFN-gamma, IL-4, IL-6, and IL-10 a tendency for decreased amounts of IL-4 and TNF-alpha compared to the marginated neutrophils. Localization of the neutrophils to the kidney interstitium was confirmed by high resolution microscopy and these sites of transmigration were directly associated with areas of increased vascular permeability. Activation of the adenosine 2A receptor significantly decreased both kidney neutrophil transmigration by about half and vascular permeability by about a third. After unilateral renal ischemia-reperfusion, the unclipped kidney and lungs did not accumulate interstitial neutrophils or have increased vascular permeability despite a marked increase of neutrophil margination in the lungs. Our findings suggest there is a sequential recruitment and transmigration of neutrophils from the vasculature into the kidney interstitium at the site of tissue injury following renal ischemia-reperfusion.

Large-scale molecular and tissue microarray analysis of mesothelin expression in common human carcinomas

The 40-kilodalton processed glycoprotein, mesothelin, is highly expressed in epithelial mesotheliomas and adenocarcinomas of the ovary (serous papillary) and pancreas, but its expression in a large series of other common carcinomas has not been completely explored. In the present study, we used oligonucleotide and tissue microarrays to profile the expression of the mesothelin gene (MSLN) and encoded protein, respectively. Among 150 carcinomas of multiple anatomic sites, we found the highest average expression of MSLN in serous carcinomas of the ovary and adenocarcinomas of the pancreas, consistent with previous reports, as well as measurable but less-striking expression in pulmonary, gastric/esophageal, and colorectal adenocarcinomas. On tissue microarrays containing 621 carcinomas derived from the same and additional sites as those profiled by gene expression, mesothelin immunoreactivity was highest in cancers of the ovary (serous papillary, endometrioid, and undifferentiated) and pancreas, with less frequent staining seen in adenocarcinomas of the endometrium, lung, and stomach/esophagus. Some immunopositivity was observed in 42% of pulmonary adenocarcinomas, including 18% that had >50% of tumor cells that were immunoreactive. Some 14% of breast and 30% of colorectal adenocarcinomas showed immunopositivity, but no case contained >50% tumor cells that were immunoreactive. Mesothelin was either entirely absent or present in <5% of carcinomas of the prostate, bladder/ureter, liver, kidney, and thyroid. Overall, we observed good concordance between the results obtained by oligonucleotide and tissue microarrays. This large study of the MSLN gene and protein expression in common carcinomas provides data for future investigations that evaluate the utility of mesothelin/megakaryocyte potentiating factor as a potential serum tumor marker or target of immunotoxin-based therapy in human cancers.

Banff Schema for Grading Pancreas Allograft Rejection: Working Proposal by a Multi-Disciplinary International Consensus Panel

Accurate diagnosis and grading of rejection and other pathological processes are of paramount importance to guide therapeutic interventions in patients with pancreas allograft dysfunction. A multi‐disciplinary panel of pathologists, surgeons and nephrologists was convened for the purpose of developing a consensus document delineating the histopathological features for diagnosis and grading of rejection in pancreas transplant biopsies. Based on the available published data and the collective experience, criteria for the diagnosis of acute cell‐mediated allograft rejection (ACMR) were established. Three severity grades (I/mild, II/moderate and III/severe) were defined based on lesions known to be more or less responsive to treatment and associated with better‐ or worse‐graft outcomes, respectively. The features of chronic rejection/graft sclerosis were reassessed, and three histological stages were established. Tentative criteria for the diagnosis of antibody‐mediated rejection were also characterized, in anticipation of future studies that ought to provide more information on this process. Criteria for needle core biopsy adequacy and guidelines for pathology reporting were also defined.

DICER1 mutations in childhood cystic nephroma and its relationship to DICER1-renal sarcoma.

The pathogenesis of cystic nephroma of the kidney has interested pathologists for over 50 years. Emerging from its initial designation as a type of unilateral multilocular cyst, cystic nephroma has been considered as either a developmental abnormality or a neoplasm or both. Many have viewed cystic nephroma as the benign end of the pathologic spectrum with cystic partially differentiated nephroblastoma and Wilms tumor, whereas others have considered it a mixed epithelial and stromal tumor. We hypothesize that cystic nephroma, like the pleuropulmonary blastoma in the lung, represents a spectrum of abnormal renal organogenesis with risk for malignant transformation. Here we studied DICER1 mutations in a cohort of 20 cystic nephromas and 6 cystic partially differentiated nephroblastomas, selected independently of a familial association with pleuropulmonary blastoma and describe four cases of sarcoma arising in cystic nephroma, which have a similarity to the solid areas of type II or III pleuropulmonary blastoma. The genetic analyses presented here confirm that DICER1 mutations are the major genetic event in the development of cystic nephroma. Further, cystic nephroma and pleuropulmonary blastoma have similar DICER1 loss of function and ‘hotspot’ missense mutation rates, which involve specific amino acids in the RNase IIIb domain. We propose an alternative pathway with the genetic pathogenesis of cystic nephroma and DICER1-renal sarcoma paralleling that of type I to type II/III malignant progression of pleuropulmonary blastoma.

The urine microRNA profile may help monitor post-transplant renal graft function.

Non-invasive, cost-effective biomarkers that allow accurate monitoring of graft function are needed in kidney transplantation. Since microRNAs (miRNAs) have emerged as promising disease biomarkers we sought to establish an miRNA signature in urinary cell pellets comparing kidney transplant patients diagnosed with chronic allograft dysfunction (CAD) with interstitial fibrosis and tubular atrophy and those recipients with normal graft function. Overall, we evaluated 191 samples from 125 deceased donor primary kidney transplant recipients in the discovery, initial validation and the longitudinal validation studies for non-invasive monitoring of graft function. Of 1,733 mature miRNAs studied using microarrays, 22 were found to be differentially expressed between groups. Ontology and pathway analyses showed inflammation as the principal biological function associated with these miRNAs. Twelve selected miRNAs were longitudinally evaluated in urine samples of an independent set of 66 patients, at two time-points post-kidney transplant. A subset of these miRNAs was found to be differentially expressed between groups early post-kidney transplant before histological allograft injury was evident. Thus, a panel of urine miRNAs was identified as potential biomarkers for monitoring graft function and anticipating progression to CAD in kidney transplant patients.

Podoplanin is a better immunohistochemical marker for sarcomatoid mesothelioma than calretinin.

Immunohistochemistry using a broad panel of markers is an invaluable tool for diagnosing sarcomatoid mesothelioma. Membranous podoplanin staining has been proposed as a specific and sensitive marker to distinguish epithelioid mesothelioma from adenocarcinoma. We found that cytoplasmic podoplanin staining was present in sarcomatoid mesotheliomas, and wanted to explore the reproducibility and specificity of this staining pattern. Immunohistochemistry for podoplanin, using 2 podoplanin antibodies (antipodoplanin and D2-40), was performed in 55 mesotheliomas (24 epithelioid, 18 sarcomatoid, and 13 biphasic), 80 pulmonary adenocarcinomas, 8 synovial sarcomas, and 16 sarcomatoid carcinomas. Expression of calretinin, vimentin, MOC31, and TTF-1 was also examined in all adenocarcinomas, sarcomatoid carcinomas, 7 synovial sarcomas, and 21 of the mesotheliomas. Calretinin staining performed previously on an additional 31 mesotheliomas was reviewed. Using membranous or cytoplasmic staining as indicative of positivity, we found that antipodoplanin and D2-40 each stained 84% of mesotheliomas (antipodoplanin: 46/55; D2-40: 38/44), including 72% of sarcomatoid mesotheliomas (antipodoplanin: 13/18; D2-40: 11/14). With antipodoplanin antibody, no staining was seen in the pulmonary adenocarcinomas (0/80, 0%) or the synovial sarcomas (0/8, 0%), and weak cytoplasmic staining was seen in only 1 sarcomatoid carcinoma (1/15, 7%). D2-40 showed similar results, staining 3% (2/80) of pulmonary adenocarcinomas, 13% (1/8) of synovial sarcomas, and 8% (1/13) of sarcomatoid carcinomas. Overall sensitivities and specificities were 84% and 99% for antipodoplanin, and 86% and 96% for D2-40. These findings suggest that cytoplasmic podoplanin expression may be useful in the diagnosis of sarcomatoid mesothelioma, although it should be used with caution on biopsy material.

Immunophenotypic differences between intestinal-type and low-grade papillary sinonasal adenocarcinomas: An immunohistochemical study of 22 cases utilizing CDX2 and MUC2

Nonsalivary sinonasal adenocarcinomas can be divided into low-grade and high-grade tumors. The former are often papillary and the latter are usually of intestinal type, morphologically similar to metastatic colonic carcinoma. Antibodies to CDX2, a transcription factor gene highly specific for intestinal adenocarcinomas, MUC2, a mucin gene expressed in adenocarcinomas from various sites, and cytokeratins (CK) 7 and 20 were used to examine the two groups of tumors. Formalin-fixed, paraffin-embedded tissue from 22 sinonasal adenocarcinomas was reclassified into 9 high-grade intestinal-type, 3 high-grade nonintestinal, and 10 low-grade, predominantly papillary adenocarcinomas. Immunohistochemical staining was graded on a 0 to 4+ scale with 5% or greater tumor cell staining considered positive. Of the high-grade intestinal group, 78% demonstrated 4+ CDX2 positivity, with 44% MUC2 positive. Although 89% of this group was CK7 positive, the percent of staining was variable. A majority (67%) of the intestinal cases was 4+ CK20 positive. Almost every nonintestinal adenocarcinoma (90%) (low- and high-grade) was CK7 positive (7 of 9, 4+), without expression of any of the three colonic adenocarcinoma markers. The three high-grade nonintestinal tumors had the expression profile of the low-grade papillary group with the exception of focal MUC2 positivity in 1 case. Intestinal-type adenocarcinomas have an expression profile distinct from nonintestinal sinonasal adenocarcinomas. The former are similar, but not identical, to colonic adenocarcinomas. Immunohistochemical staining for CDX2, MUC2, and differential cytokeratins does not differentiate metastatic colorectal from primary sinonasal intestinal-type adenocarcinoma.

Low-grade sinonasal adenocarcinomas: the association with and distinction from respiratory epithelial adenomatoid hamartomas and other glandular lesions.

Sinonasal adenocarcinomas (SNACs) are uncommon malignancies that show a variety of growth patterns. These lesions are classified as intestinal or nonintestinal, the latter subclassified as low grade or high grade. We have noted that some low-grade nonintestinal SNACs are associated with respiratory epithelial adenomatoid hamartomas (REAHs), also rare lesions that have recently been shown to be neoplastic. We reviewed 29 nonintestinal low-grade SNACs seen at our institution over a 20-year period, with particular attention to morphology and concomitant REAHs. Nine (31%) low-grade SNACs demonstrated a predominantly exophytic and papillary growth pattern, and 18 (72%) had a more tubular growth pattern. Two (7%) were categorized as “other.” Six low-grade tubular SNACs were associated with REAHs. An immunohistochemical panel was performed on 2 of these cases; neoplastic cells were immunoreactive with antibodies to CK7 and S100 protein and nonreactive with antibodies to CK20, similar to other low-grade SNACs. No basal cells or myoepithelial differentiation was seen with immunohistochemical stains for p63 and 34βE12. This association of low-grade tubular SNACs with REAHs suggests that REAHs may be related to some adenocarcinomas.

Cgnz1 allele confers kidney resistance to damage preventing progression of immune complex–mediated acute lupus glomerulonephritis

The mechanisms regulating acute and chronic glomerulonephritis are dependent on different genetic mechanisms, where the Cgnz1 allele confers kidney protection in immune complex–mediated proliferative lupus nephritis.

Evaluation of molecular profiles in calcineurin inhibitor toxicity post-kidney transplant: input to chronic allograft dysfunction.

The molecular basis of calcineurin inhibitor toxicity (CNIT) in kidney transplantation (KT) and its contribution to chronic allograft dysfunction (CAD) with interstitial fibrosis (IF) and tubular atrophy (TA) were evaluated by: (1) identifying specific CNIT molecular pathways that associate with allograft injury (cross‐sectional study) and (2) assessing the contribution of the identified CNIT signature in the progression to CAD with IF/TA (longitudinal study). Kidney biopsies from well‐selected transplant recipients with histological diagnosis of CNIT (n = 14), acute rejection (n = 13) and CAD with IF/TA (n = 10) were evaluated. Normal allografts (n = 18) were used as controls. To test CNIT contribution to CAD progression, an independent set of biopsies (n = 122) from 61 KT patients collected at 3 and ∼12 months post‐KT (range = 9–18) were evaluated. Patients were classified based on 2‐year post‐KT graft function and histological findings as progressors (n = 30) or nonprogressors to CAD (n = 31). Molecular signatures characterizing CNIT samples were identified. Patients classified as progressors showed an overlap of 7% and 22% with the CNIT signature at 3 and at ∼12 months post‐KT, respectively, while the overlap was <1% and 1% in nonprogressor patients, showing CNIT at the molecular level as a nonimmunological factor involved in the progression to CAD.