James L. Burchette

Diagnosis And Management Of Bk Polyomavirus Interstitial Nephritis In Renal Transplant Recipients

BACKGROUND Interstitial nephritis caused by BK polyomavirus is a recognized complication of renal transplantation. A study of renal transplant recipients at Duke University Medical Center was undertaken to evaluate diagnostic modalities and assess clinical outcomes in transplant polyomavirus infections. METHODS Polyomavirus nephritis was identified in 6 of 240 patients who received renal transplants between January 1996 and June 1998 and an additional patient who underwent transplantation in 1995. The clinical records of these seven patients were reviewed, as were all renal biopsy and nephrectomy specimens. Electron microscopy (EM) was performed on negatively stained urine samples from 6 patients with polyomavirus infection and 23 patients with other diagnoses. RESULTS Patients with polyomavirus infection shared several clinical features, including ureteral obstruction (5/7 patients), lymphocele (3/7), bacterial urinary tract infection (3/7), hematuria (3/7), cytomegalovirus infection (3/7), and immunosuppression with mycophenolate mofetil (6/7). All patients experienced elevations in serum creatinine, which stabilized or decreased in four patients with altered or decreased immunosuppression. The diagnosis of polyomavirus infection was established by renal biopsy and EM of urine in five patients, by biopsy alone in one, and by EM alone in one. Sequential examinations of urine by EM were used to monitor the course of infection in six patients. CONCLUSIONS Interstitial nephritis due to BK polyomavirus occurred in 2.5% of patients receiving renal transplants at our center since 1996. Polyomavirus infection can cause transplant dysfunction and graft loss, but progression of the infection can frequently be abrogated with alterations in immunosuppressive therapy. Both renal biopsy and EM of urine samples are useful in the diagnosis and monitoring of polyomavirus infections.

Immunoreactive prostatic specific antigen in male periurethral glands.

Prostatic specific antigen (PSA) is considered an antigen unique to benign and malignant prostatic tissue. Recent evidence in the literature has raised serious doubts about the specificity of this antigen. In this study twenty male urethral specimens were evaluated for PSA and prostatic acid phosphatase (PAP) from patients without evidence of prostatic cancer. Eight of these 20 urethral specimens exhibited strong immunostaining for both PSA and PAP, localized in the periurethral glands. Five of the 17 urethral biopsies were positive for both antigens, while all three of the whole mount autopsy specimens stained positive for PSA and PAP. Within the autopsy series, there was heterogenous staining of the periurethral glands within the same specimen. This evidence disproves the fact that PSA and PAP are organ specific as previously described. More than likely any tissue of cloacal origin has potential for staining positive for prostatic specific antigen and prostatic acid phosphatase.

Stimulation of lymphocyte responses by angiotensin II promotes kidney injury in hypertension

Activation of the renin-angiotensin system contributes to the progression of chronic kidney disease. Based on the known cellular effects of ANG II to promote inflammation, we posited that stimulation of lymphocyte responses by ANG II might contribute to the pathogenesis of hypertensive kidney injury. We therefore examined the effects of the immunosuppressive agent mycophenolate mofetil (MMF) on the course of hypertension and kidney disease induced by chronic infusion of ANG II in 129/SvEv mice. Although it had no effect on the severity of hypertension or cardiac hypertrophy, treatment with MMF significantly reduced albuminuria and ameliorated kidney injury, decreasing glomerulosclerosis and reducing lymphocyte infiltration into the renal interstitium. Attenuation of renal pathology with MMF was associated with reduced expression of mRNAs for the proinflammatory cytokines interferon-gamma and tumor necrosis factor-alpha and the profibrotic cytokine transforming growth factor-beta. As infiltration of the kidney by T lymphocytes was a prominent feature of ANG II-dependent renal injury, we carried out experiments examining the effects of ANG II on lymphocytes in vitro. We find that exposure of splenic lymphocytes to ANG II causes prominent rearrangements of the actin cytoskeleton. These actions require the activity of Rho kinase. Thus, ANG II exaggerates hypertensive kidney injury by stimulating lymphocyte responses. These proinflammatory actions of ANG II seem to have a proclivity for inducing kidney injury while having negligible actions in the pathogenesis of cardiac hypertrophy.

Hedgehog pathway activation parallels histologic severity of injury and fibrosis in human nonalcoholic fatty liver disease

The Hedgehog (HH)‐signaling pathway mediates several processes that are deregulated in patients with metabolic syndrome (e.g., fat mass regulation, vascular/endothelial remodeling, liver injury and repair, and carcinogenesis). The severity of nonalcoholic fatty liver disease (NAFLD) and metabolic syndrome generally correlate. Therefore, we hypothesized that the level of HH‐pathway activation would increase in parallel with the severity of liver damage in NAFLD. To assess potential correlations between known histologic and clinical predictors of advanced liver disease and HH‐pathway activation, immunohistochemistry was performed on liver biopsies from a large, well‐characterized cohort of NAFLD patients (n = 90) enrolled in the Nonalcoholic Steatohepatitis Clinical Research Network (NASH CRN) Database 1 study. Increased HH activity (evidenced by accumulation of HH‐ligand–producing cells and HH‐responsive target cells) strongly correlated with portal inflammation, ballooning, and fibrosis stage (each P < 0.0001), supporting a relationship between HH‐pathway activation and liver damage. Pathway activity also correlated significantly with markers of liver repair, including numbers of hepatic progenitors and myofibroblastic cells (both P < 0.03). In addition, various clinical parameters that have been linked to histologically advanced NAFLD, including increased patient age (P < 0.005), body mass index (P < 0.002), waist circumference (P < 0.0007), homeostatic model assessment of insulin resistance (P < 0.0001), and hypertension (P < 0.02), correlated with hepatic HH activity. Conclusion: In NAFLD patients, the level of hepatic HH‐pathway activity is highly correlated with the severity of liver damage and with metabolic syndrome parameters that are known to be predictive of advanced liver disease. Hence, deregulation of the HH‐signaling network may contribute to the pathogenesis and sequelae of liver damage that develops with metabolic syndrome. (HEPATOLOGY 2012;55:1711–1721)

Increased production of sonic hedgehog by ballooned hepatocytes

Ballooned hepatocytes distinguish non‐alcoholic steatohepatitis (NASH) from steatosis. Such cells contain dilated endoplasmic reticulum and ubiquitin aggregates, characteristics of endoplasmic reticulum stress. Hepatocyte ballooning increases the risk for fibrosis in NASH, suggesting that ballooned hepatocytes release pro‐fibrogenic factors. Hedgehog ligands function as pro‐fibrogenic factors in liver diseases, but mechanisms for hedgehog ligand production remain poorly understood. We evaluated the hypothesis that endoplasmic reticulum stress induces hepatocyte production of hedgehog ligands that provide paracrine pro‐fibrogenic signals to neighbouring cells. In livers from NASH patients, keratin 8/18 and ubiquitin staining demonstrated enlarged, keratin 8/18‐negative/ubiquitin‐positive hepatocytes (ballooned hepatocytes) that were positive for Sonic hedgehog. In order to model endoplasmic reticulum stress in vitro, primary mouse hepatocytes were treated with tunicamycin. Compared to vehicle, tunicamycin significantly increased Sonic hedgehog and Indian hedgehog expression. Furthermore, conditioned medium from tunicamycin‐treated hepatocytes increased Gli‐luciferase reporter activity 14‐fold more than conditioned medium from vehicle‐treated hepatocytes. Cyclopamine (hedgehog signalling inhibitor) abrogated the effect of conditioned medium from tunicamycin‐treated hepatocytes, verifying that soluble hepatocyte‐derived factors activate hedgehog signalling. Ballooned hepatocytes in NASH patients did not express the hedgehog target gene, Gli2, α‐smooth muscle actin or vimentin, but were surrounded by Gli2‐positive stromal cells expressing these myofibroblast markers. Trichrome staining demonstrated the accumulation of ballooned hepatocytes in areas of matrix deposition, and numbers of Sonic hedgehog‐positive hepatocytes correlated with the degree of ballooning and fibrosis stage. Hepatocytes undergoing endoplasmic reticiulum stress generate hedgehog ligands which act as paracrine pro‐fibrogenic factors for hedgehog‐responsive stromal cells. These results help to explain why fibrosis stage correlates with hepatocyte ballooning in NASH. Copyright

Desmoplastic (sclerotic) nevus: an underrecognized entity that resembles dermatofibroma and desmoplastic melanoma.

Desmoplastic (sclerotic) nevus, a benign melanocytic neoplasm characterized by predominantly spindle-shaped nevus cells within a fibrotic stroma, can be confused with fibrous lesions and other melanocytic proliferations, including desmoplastic melanoma. We compared the histologic and immunohistochemical features of 16 desmoplastic nevi, nine desmoplastic melanomas, four hypopigmented blue nevi, and six dermatofibromas. The similarities between desmoplastic nevi and dermatofibromas included epidermal hyperplasia (12 of 16), presence of keloidal collagen (15 of 16), hypercellularity (16 of 16), and increased numbers of factor XIIIa-positive dendritic cells (12 of 12). The absence of adnexal induction (0 of 16), the rarity of lesions with multinucleated cells (3 of 16) or epidermal hyperpigmentation (2 of 16), and the presence of S-100 immunoreactivity (16 of 16) and melanocytic proliferation (9 of 16) helped differentiate desmoplastic nevi from dermatofibromas. The similarities between desmoplastic nevi and desmoplastic melanomas included the presence of atypical cells (16 of 16) and HMB-45 expression in the superficial portion of the lesions (11 of 16). The infrequent location on the head or neck (1 of 16), the absence of mitotic figures (0 of 16), a significantly lower number of Ki-67-reactive cells, and a decrease in HMB-45 expression in the deep area of the lesions (8 of 11) helped distinguish desmoplastic nevi from desmoplastic melanoma. Desmoplastic nevi had overlapping features with hypopigmented blue nevi, but features tending to favor the latter included a predominance of ovoid nuclei, higher numbers of atypical cells, and homogeneous staining with HMB-45. We conclude that a combination of histologic and immunohistochemical criteria facilitates the reliable diagnosis of desmoplastic nevus from its simulators.

Extramammary Paget Disease Is Characterized by the Consistent Lack of Estrogen and Progesterone Receptors But Frequently Expresses Androgen Receptor

Extramammary Paget disease (EPD) is an uncommon cutaneous malignant neoplasm that arises in areas rich in apocrine glands (perineum, vulva, and axilla). Apocrine gland origin or apocrine differentiation of cells of EPD has been suggested. Estrongen, progesterone, and androgen hormone receptors have been reported to exhibit a characteristic pattern of expression in mammary apocrine type carcinomas; however, their expression in EPD has not been elucidated fully. By using immunohistochemical methods, we studied the expression of steroid receptors in EPD on formalin-fixed paraffin-embedded tissue samples from 28 patients with EPD without associated visceral malignant neoplasms or adnexal carcinoma. Androgen receptor (AR) was identified in 15 of 28 cases. The proportion of AR-positive cells varied from 1% to more than 75%; 8 cases expressed AR in more than 10% of cells. Strong AR expression also was seen in the invasive carcinoma arising from 1 case of EPD. All cases lacked immunohistochemically detectable estrogen and progesterone receptors. The immunophenotype characteristic of apocrine carcinomas (AR-positive, estrogen receptor-negative, progesterone receptor-negative) was seen in a substantial proportion of EPD cases. Results suggest that AR expression is a factor in pathogenesis of EPD. This may be important for the therapy of recurrent or invasive disease.

CD10 expression in trichoepithelioma and basal cell carcinoma

Background:  Trichoepithelioma (TE) is a benign neoplasm that shares both clinical and histologic features with basal cell carcinoma (BCC). However, it is important to distinguish these neoplasms. Limited immunohistochemical stains are available to separate these two tumors.

Mutations in the Gene That Encodes the F-Actin Binding Protein Anillin Cause FSGS

FSGS is characterized by segmental scarring of the glomerulus and is a leading cause of kidney failure. Identification of genes causing FSGS has improved our understanding of disease mechanisms and points to defects in the glomerular epithelial cell, the podocyte, as a major factor in disease pathogenesis. Using a combination of genome-wide linkage studies and whole-exome sequencing in a kindred with familial FSGS, we identified a missense mutation R431C in anillin (ANLN), an F-actin binding cell cycle gene, as a cause of FSGS. We screened 250 additional families with FSGS and found another variant, G618C, that segregates with disease in a second family with FSGS. We demonstrate upregulation of anillin in podocytes in kidney biopsy specimens from individuals with FSGS and kidney samples from a murine model of HIV-1-associated nephropathy. Overexpression of R431C mutant ANLN in immortalized human podocytes results in enhanced podocyte motility. The mutant anillin displays reduced binding to the slit diaphragm-associated scaffold protein CD2AP. Knockdown of the ANLN gene in zebrafish morphants caused a loss of glomerular filtration barrier integrity, podocyte foot process effacement, and an edematous phenotype. Collectively, these findings suggest that anillin is important in maintaining the integrity of the podocyte actin cytoskeleton.

A Novel Role for Type 1 Angiotensin Receptors on T Lymphocytes to Limit Target Organ Damage in Hypertension

Rationale: Human clinical trials using type 1 angiotensin (AT1) receptor antagonists indicate that angiotensin II is a critical mediator of cardiovascular and renal disease. However, recent studies have suggested that individual tissue pools of AT1 receptors may have divergent effects on target organ damage in hypertension. Objective: We examined the role of AT1 receptors on T lymphocytes in the pathogenesis of hypertension and its complications. Methods and Results: Deficiency of AT1 receptors on T cells potentiated kidney injury during hypertension with exaggerated renal expression of chemokines and enhanced accumulation of T cells in the kidney. Kidneys and purified CD4+ T cells from “T cell knockout” mice lacking AT1 receptors on T lymphocytes had augmented expression of Th1-associated cytokines including interferon-&ggr; and tumor necrosis factor-&agr;. Within T lymphocytes, the transcription factors T-bet and GATA-3 promote differentiation toward the Th1 and Th2 lineages, respectively, and AT1 receptor-deficient CD4+ T cells had enhanced T-bet/GATA-3 expression ratios favoring induction of the Th1 response. Inversely, mice that were unable to mount a Th1 response due to T-bet deficiency were protected from kidney injury in our hypertension model. Conclusions: The current studies identify an unexpected role for AT1 receptors on T lymphocytes to protect the kidney in the setting of hypertension by favorably modulating CD4+ T helper cell differentiation.