👤 Lynn D Cornell

Most newly discovered membranous nephropathy (MN) antigens have been mutually exclusive, but there are rare cases of dual antigen MN based on immunohistochemistry (IHC)/immunofluorescence (IF) or serologic testing. Here, we searched for cases of dual antigen MN at Mayo Clinic and Arkana Laboratories with the diagnosis established by light/electron microscopy and IF. At Mayo Clinic, we performed laser capture microdissection of glomeruli followed by liquid chromatography tandem mass spectrometry (LC MS/MS) on paraffin-embedded kidney biopsy tissue to detect 12 MN antigens. Nine cases of dual antigen MN (four at Mayo Clinic, five at Arkana Laboratories) were confirmed by both LC MS/MS and IHC/IF. The detected antigens were NELL1 + CNTN1 (two cases), NCAM1 + EXT1/2 (two cases), and one case each NDNF + NELL1, NELL1 + PLA2R1, THSD7A + PLA2R1, PCDH7 + PLA2R1, and CNTN1 + PCDH7. Median age at diagnosis was 68 years (range 23-84). Eight patients presented with nephrotic syndrome and microscopic hematuria. Median serum creatinine at diagnosis was 1 mg/dL. The underlying conditions, when present, and serological characteristics, correlated with the involved antigens. The frequency at Mayo Clinic was 2.6% of PLA2R1-negative MN cases. Given that IHC/IF and LC MS/MS for MN antigen detection are typically not pursued in PLA2R1-associated MN, dual-antigen MN is likely underdiagnosed. Dual-antigen MN can involve a variety of MN antigens, including those that are podocyte-expressed, transmembrane, or secreted. Most patients with MN present with nephrotic syndrome and microscopic hematuria. Further studies are needed to understand the pathophysiology of dual-antigen MN and determine their role both in the therapeutic approach and clinical outcomes. Our findings suggest that LC MS/MS is a valuable methodology for detection of dual antigen MN. Show less

Melanoma cells evade drug treatment by changing their phenotype from proliferative to migrative cells and vice versa in a process known as phenotype switching. The Microphthalmia-associated transcription factor (MITF) is a key regulator of phenotype switching in melanoma. Previous studies have shown that loss of MITF affects the expression of epithelial-to-mesenchymal transition marker genes such as E-cadherin (CDH1) and N-cadherin (CDH2). However, the specific roles of CDH1 and CDH2 in phenotype switching as well as their direct correlation with MITF remain unclear. This study aimed to investigate how MITF regulates CDH1 expression in melanoma. The results showed that a 1 kb intronic CDH1 fragment (CDH1-B) leads to MITF-dependent activation of CDH1 expression through specific binding sites. Although MITF represses the expression of the epithelial-to-mesenchymal transition transcription factors SNAIL, ZEB1, and TWIST1, knockdown of SNAI1 and TWIST1 did not affect CDH1 expression or expression from the CDH1-B element. In addition, ZEB1 did not affect expression from the CDH1-B element, suggesting that MITF activates CDH1 directly through this regulatory element. Our results show the direct role of MITF in regulating CDH1 expression in melanoma, highlighting an important step in the phenotype switching process. Show less

In patients with secondary (autoimmune) membranous nephropathy, two novel proteins, Exostosin 1 and Exostosin 2 (EXT1/EXT2), are potential disease antigens, biomarkers, or both. In this study, we validate the EXT1/EXT2 findings in a large cohort of membranous lupus nephritis. We conducted a retrospective cohort study of patients with membranous lupus nephritis, and performed immunohistochemistry studies on the kidney biopsy specimens against EXT1 and EXT2. Clinicopathologic features and outcomes of EXT1/EXT2-positive versus EXT1/EXT2-negative patients were compared. Our study cohort included 374 biopsy-proven membranous lupus nephritis cases, of which 122 (32.6%) were EXT1/EXT2-positive and 252 (67.4%) were EXT1/EXT2-negative. EXT1/EXT2-positive patients were significantly younger ( The prevalence of EXT1/EXT2 positivity was 32.6% in our cohort of membranous lupus nephritis. Compared with EXT1/EXT2-negative membranous lupus nephritis, EXT1/EXT2-positive disease appears to represent a subgroup with favorable kidney biopsy findings with respect to chronicity indices. Cases of membranous lupus nephritis that are EXT1/EXT2-negative are more likely to progress to ESKD compared with those that are EXT1/EXT2-positive. Show less

Common fragile sites (CFSs) are large regions with profound genomic instability that often span extremely large genes a number of which have been found to be important tumor suppressors. RNA sequencing previously revealed that there was a group of six large CFS genes which frequently had decreased expression in oropharyngeal squamous cell carcinomas (OPSCCs) and real-time reverse transcriptase polymerase chain reaction experiments validated that these six large CFS genes (PARK2, DLG2, NBEA, CTNNA3, DMD, and FHIT) had decreased expression in most of the tumor samples. In this study, we investigated whether the decreased expression of these genes has any clinical significance in OPSCCs. We analyzed the six CFS large genes in 45 OPSCC patients and found that 27 (60%) of the OPSCC tumors had decreased expression of these six genes. When we correlated the expression of these six genes to each patient's clinical records, for 11 patients who had tumor recurrence, 10 of them had decreased expression of almost all 6 genes. When we divided the patients into two groups, one group with decreased expression of the six genes and the other group with either slight changes or increased expression of the six genes, we found that there is significant difference in the incidence of tumor recurrence between these two groups by Kaplan-Meier plot analysis (P < .05). Our results demonstrated that those OPSCC tumors with decreased expression of this select group of six large CFS genes were much more likely to be associated with tumor recurrence and these genes are potential prognostic markers for predicting tumor recurrence in OPSCC. Show less

The kidney is the organ most commonly involved in systemic amyloidosis. This study reports the largest clinicopathologic series of renal amyloidosis. This study provides characteristics of 474 renal amyloidosis cases evaluated at the Mayo Clinic Renal Pathology Laboratory from 2007 to 2011, including age, sex, serum creatinine, proteinuria, type of amyloid, and tissue distribution according to type. The type of amyloid was Ig amyloidosis in 407 patients (85.9%), AA amyloidosis in 33 (7.0%), leukocyte chemotactic factor 2 amyloidosis in 13 (2.7%), fibrinogen A α chain amyloidosis in 6 (1.3%), Apo AI, Apo AII, or Apo AIV amyloidosis in 3 (0.6%), combined AA amyloidosis/Ig heavy and light chain amyloidosis in 1 (0.2%), and unclassified in 11 (2.3%). Laser microdissection/mass spectrometry, performed in 147 cases, was needed to determine the origin of amyloid in 74 of the 474 cases (16%), whereas immunofluorescence failed to diagnose 28 of 384 light chain amyloidosis cases (7.3%). Leukocyte chemotactic factor 2 amyloidosis and Apo AI, Apo AII, or Apo AIV amyloidosis were characterized by diffuse interstitial deposition, whereas fibrinogen A α chain amyloidosis showed obliterative glomerular involvement. Compared with other types, Ig amyloidosis was associated with lower serum creatinine, higher degree of proteinuria, and amyloid spicules. In the authors' experience, the vast majority of renal amyloidosis cases are Ig derived. The newly identified leukocyte chemotactic factor 2 amyloidosis form was the most common of the rarer causes of renal amyloidosis. With the advent of laser microdissection/mass spectrometry for amyloid typing, the origin of renal amyloidosis can be determined in >97% of cases. Show less