Neriman Gokden

Resveratrol improves renal microcirculation, protects the tubular epithelium, and prolongs survival in a mouse model of sepsis-induced acute kidney injury.

The mortality rate of patients who develop acute kidney injury during sepsis nearly doubles. The effectiveness of therapy is hampered because it is usually initiated only after the onset of symptoms. As renal microvascular failure during sepsis is correlated with the generation of reactive nitrogen species, the therapeutic potential of resveratrol, a polyphenol vasodilator that is also capable of scavenging reactive nitrogen species, was investigated using the cecal ligation and puncture (CLP) murine model of sepsis-induced acute kidney injury. Resveratrol when given at 5.5 h following CLP reversed the decline in cortical capillary perfusion, assessed by intravital microscopy, at 6 h in a dose-dependent manner. Resveratrol produced the greatest improvement in capillary perfusion and increased renal blood flow and the glomerular filtration rate without raising systemic pressure. A single dose at 6 h after CLP was unable to improve renal microcirculation assessed at 18 h; however, a second dose at 12 h significantly improved microcirculation and decreased the levels of reactive nitrogen species in tubules, while improving renal function. Moreover, resveratrol given at 6, 12, and 18 h significantly improved survival. Hence, resveratrol may have a dual mechanism of action to restore the renal microcirculation and scavenge reactive nitrogen species, thus protecting the tubular epithelium even when administered after the onset of sepsis.

Evidence for the Role of Reactive Nitrogen Species in Polymicrobial Sepsis-Induced Renal Peritubular Capillary Dysfunction and Tubular Injury

Acute kidney injury (AKI) remains a frequent and serious complication of human sepsis that contributes significantly to mortality. For better understanding of the development of AKI during sepsis, the cecal ligation and puncture (CLP) murine model of sepsis was studied using intravital video microscopy (IVVM) of the kidney. IVVM with FITC-dextran was used to determine the percentage of capillaries with continuous, intermittent or no flow at 0 (sham), 10, 16, and 22 h after CLP. There was a dramatic fall in capillary perfusion as early as 10 h after CLP that persisted through 22 h. The percentage of vessels with continuous flow at 16 h decreased from 73 +/- 2% in shams to 16 +/- 2% (P < 0.05), whereas the percentage of vessels with no flow increased from 4 +/- 1% in shams to 42 +/- 2% (P < 0.05). The capillary perfusion defect preceded the rise in serum creatinine. IVVM with dihydrorhodamine-123 was used to quantify in real time reactive nitrogen species (RNS) generation by renal tubules, and the inducible nitric oxide synthase inhibitor L-iminoethyl-lysine (mg/kg) was used to examine the role of inducible nitric oxide synthase inhibitor on capillary dysfunction and RNS generation. Tubular generation of RNS was significantly elevated at 10 h after CLP and was associated with tubules that were bordered by capillaries with reduced perfusion. L-iminoethyl-lysine significantly reversed the capillary perfusion defect, blocked RNS generation, and reduced AKI. These data show that capillary dysfunction and RNS generation contribute to tubular injury and suggest that RNS should be considered a potential therapeutic target in the treatment of sepsis-induced AKI.

Development of Oxidative Stress in the Peritubular Capillary Microenvironment Mediates Sepsis-Induced Renal Microcirculatory Failure and Acute Kidney Injury

Acute kidney injury is a frequent and serious complication of sepsis. To better understand the development of sepsis-induced acute kidney injury, we performed the first time-dependent studies to document changes in renal hemodynamics and oxidant generation in the peritubular microenvironment using the murine cecal ligation and puncture (CLP) model of sepsis. CLP caused an increase in renal capillary permeability at 2 hours, followed by decreases in mean arterial pressure, renal blood flow (RBF), and renal capillary perfusion at 4 hours, which were sustained through 18 hours. The decline in hemodynamic parameters was associated with hypoxia and oxidant generation in the peritubular microenvironment and a decrease in glomerular filtration rate. The role of oxidants was assessed using the superoxide dismutase mimetic/peroxynitrite scavenger MnTMPyP [Mn(III)tetrakis(1-methyl-4-pyridyl)porphyrin]. At 10 mg/kg administered 6 hours after CLP, MnTMPyP did not alter blood pressure, but blocked superoxide and peroxynitrite generation, reversed the decline in RBF, capillary perfusion, and glomerular filtration rate, preserved tubular architecture, and increased 48-hour survival. However, MnTMPyP administered at CLP did not prevent capillary permeability or the decrease in RBF and capillary perfusion, which suggests that these early events are not mediated by oxidants. These data demonstrate that renal hemodynamic changes occur early after sepsis and that targeting the later oxidant generation can break the cycle of injury and enable the microcirculation and renal function to recover.

Immunohistochemical Distinction of Primary Adrenal Cortical Lesions from Metastatic Clear Cell Renal Cell Carcinoma: A Study of 248 Cases

The diagnosis of metastatic clear cell renal cell carcinoma (CC-RCC) can be difficult because of its morphologic heterogeneity and the increasing use of small image-guided biopsies that yield scant diagnostic material. This is further complicated by the degree of morphologic and immunophenotypic overlap with nonrenal neoplasms and tissues, such as adrenal cortex. In this study, a detailed immunoprofile of 63 adrenal cortical lesions, which included 54 cortical neoplasms, was compared with 185 metastatic CC-RCCs using traditional [anticalretinin, CD10, antichromogranin, antiepithelial membrane antigen, anti-inhibin, antimelanA, anticytokeratins (AE1/AE3 and AE1/CAM5.2), antirenal cell carcinoma marker, and antisynaptophysin)] and novel [anticarbonic anhydrase-IX, antihepatocyte nuclear factor-1b, antihuman kidney injury molecule-1 (hKIM-1), anti-PAX-2, anti-PAX-8, antisteroidogenic factor-1 (SF-1), and anti-T-cell immunoglobulin mucin-1] antibodies. Tissue microarray methodology was used to simulate small image-guided biopsies. Staining extent and intensity were scored semiquantitatively for each antibody. In comparing different intensity thresholds required for a “positive” result, a value of ≥2+ was identified as optimal for diagnostic sensitivity/specificity. For the distinction of adrenal cortical lesions from metastatic CC-RCCs, immunoreactivity for the adrenal cortical antigens SF-1 (86% adrenal; 0% CC-RCC), calretinin (89% adrenal; 10% CC-RCC), inhibin (86% adrenal; 9% CC-RCC), and melanA (86% adrenal; 10% CC-RCC) and for the renal epithelial antigens hKIM-1 (0% adrenal; 83% CC-RCC), PAX-8 (0% adrenal; 83% CC-RCC), hepatocyte nuclear factor-1b (0% adrenal; 76% CC-RCC), epithelial membrane antigen (0% adrenal; 78% CC-RCC), and carbonic anhydrase-IX (3% adrenal; 87% CC-RCC) had the most potential use. Use of novel renal epithelial markers hKIM-1 (clone AKG7) and/or PAX-8 and the adrenocortical marker SF-1 in an immunohistochemical panel for distinguishing adrenal cortical lesions from metastatic CC-RCC offers improved diagnostic sensitivity and specificity.

Sirolimus-induced thrombotic microangiopathy in a renal transplant recipient

A rare but well-documented serious adverse reaction to the administration of the calcineurin inhibitors tacrolimus and cyclosporine in renal transplant recipients is the development of medication-induced thrombotic microangiopathy. The recently introduced immunosuppressive medication sirolimus has a very similar molecular structure to tacrolimus and also binds to the same intracellular proteins. Despite these similarities with tacrolimus, sirolimus has a different side-effect profile and reportedly lacks documented specific renal toxicity. This is a case report of the isolated administration of sirolimus without a concomitant calcineurin inhibitor being associated with the development of renal transplant biopsy-proven thrombotic microangiopathy. The patient is a 47-year-old African-American woman whose primary cause of renal failure was not thrombotic micrangiopathy, and she received a 5-antigen mismatched cadaveric renal transplant. Because of preexisting nephrosclerosis in the renal transplant, this patient was never administered a calcineurin inhibitor but was always maintained on sirolimus. With recent animal data showing that sirolmus can be nephrotoxic in a renal ischemic-reperfusion model (similar to what happens with a renal transplant), the authors speculate on a mechanism for this adverse reaction.

Renal oncocytoma revisited: a clinicopathological study of 109 cases with emphasis on problematic diagnostic features

Trpkov K, Yilmaz A, Uzer D, Dishongh K M, Quick C M, Bismar T A & Gokden N
(2010) Histopathology57, 893–906

The utility of PAX-2 in distinguishing metastatic clear cell renal cell carcinoma from its morphologic mimics: an immunohistochemical study with comparison to renal cell carcinoma marker.

PAX-2 is a homeogene expressed during kidney development. Although immunohistochemical expression of PAX-2 has been described in a variety of primary renal cell carcinoma (RCC) subtypes and in metastatic RCC, its specificity as a marker of renal lineage in a metastatic setting has not been fully evaluated. In addition, its utility has not been directly compared with the most widely used antibody in this setting, renal cell carcinoma marker (RCCma). We studied PAX-2 expression in metastatic clear cell renal cell carcinoma (CC-RCC) and in a variety of nonrenal neoplasms with clear cytoplasm that may potentially mimic CC-RCC. Archival material from 27 CC-RCCs metastatic to various organs and 50 close morphologic mimics of CC-RCC were retrieved. Immunohistochemistry with PAX-2 and RCCmaπ antibodies was performed on each case. Nuclear staining (PAX-2) or membranous staining (RCCma) was scored semiquantitatively. Twenty-three of 27 (85%) metastatic CC-RCCs showed nuclear immunoreactivity for PAX-2, whereas RCCma reactivity was found in 19 of 27 (70%). The immunoprofiles of the metastatic CC-RCC were PAX-2+/RCCma+: 19 of 27 (70%), PAX-2+/RCCma−: 5 of 27 (19%), PAX-2−/RCCma+: 2 of 27 (7%), and PAX-2-/RCCma-: 1 of 27 (4%). Five of the 50 mimics of CC-RCC (10%) had at least focal nuclear reactivity with PAX-2, including 1 of 3 parathyroid carcinomas (33%), 3 of 7 clear cell carcinomas of the ovary (43%), and the 1 clear cell papillary cystadenoma of the epididymis. Membranous RCCma reactivity was identified in 26 of the 50 mimics (52%). We conclude that PAX-2 is a useful marker for distinguishing metastatic CC-RCC from its potential morphologic mimics, but caution must be used in certain differential diagnostic settings where nonrenal tumors such as parathyroid carcinoma, ovarian clear cell carcinoma, and clear cell papillary cystadenoma of the epididymis were shown to express both PAX-2 and RCCma.

Hemodynamic changes in the kidney in a pediatric rat model of sepsis-induced acute kidney injury

Sepsis is a leading cause of acute kidney injury (AKI) and mortality in children. Understanding the development of pediatric sepsis and its effects on the kidney are critical in uncovering new therapies. The goal of this study was to characterize the development of sepsis-induced AKI in the clinically relevant cecal ligation and puncture (CLP) model of peritonitis in rat pups 17-18 days old. CLP produced severe sepsis demonstrated by time-dependent increase in serum cytokines, NO, markers of multiorgan injury, and renal microcirculatory hypoperfusion. Although blood pressure and heart rate remained unchanged after CLP, renal blood flow (RBF) was decreased 61% by 6 h. Renal microcirculatory analysis showed the number of continuously flowing cortical capillaries decreased significantly from 69 to 48% by 6 h with a 66% decrease in red blood cell velocity and a 57% decline in volumetric flow. The progression of renal microcirculatory hypoperfusion was associated with peritubular capillary leakage and reactive nitrogen species generation. Sham adults had higher mean arterial pressure (118 vs. 69 mmHg), RBF (4.2 vs. 1.1 ml·min(-1)·g(-1)), and peritubular capillary velocity (78% continuous flowing capillaries vs. 69%) compared with pups. CLP produced a greater decrease in renal microcirculation in pups, supporting the notion that adult models may not be the most appropriate for studying pediatric sepsis-induced AKI. Lower RBF and reduced peritubular capillary perfusion in the pup suggest the pediatric kidney may be more susceptible to AKI than would be predicted using adults models.

Plasmacytoid Carcinoma of the Bladder: A Urothelial Carcinoma Variant With a Predilection for Intraperitoneal Spread

PURPOSE Bladder plasmacytoid carcinoma is an invasive urothelial carcinoma subtype that is emphasized for its morphological overlap with plasma cells and metastatic carcinoma. Our experience suggests frequent intraperitoneal spread that is not typical of conventional urothelial carcinoma. MATERIALS AND METHODS We identified cases of plasmacytoid urothelial carcinoma diagnosed on radical cystectomy. Patient age, gender, American Joint Committee on Cancer (7th edition) stage, metastatic spread/recurrence sites and clinical disease status at last followup were recorded. RESULTS A total of 10 male and 5 female patients 42 to 81 years old were identified. One tumor was pT2, 11 pT3 and 3 pT4. Six of 15 patients (40%) presented with lymph node metastasis and 5 (33%) had intraperitoneal metastasis at cystectomy. These initial sites of metastatic spread included the prerectal space, ovary and vagina, ovary and fallopian tube, bowel serosa, and omentum and bowel serosa in 1 case each. Three patients had subsequent metastasis involving the prerectal space, pleural fluid and small bowel serosa, and bowel serosa in 1 each. Eight patients had followup information available, including 3 who died of disease, 3 with disease and 2 with no evidence of disease. CONCLUSIONS Of the patients 33% with the plasmacytoid variant of urothelial carcinoma presented with intraperitoneal disease spread and 20% had subsequent metastasis involving serosal surfaces. The possibility of noncontiguous intraperitoneal spread involving serosal surfaces should be recognized to ensure proper intraoperative staging and clinical followup for patients with plasmacytoid carcinoma.

Dermatofibrosarcoma protuberans of the vulva and groin: detection of COL1A1‐PDGFB fusion transcripts by RT‐PCR

Background:  Dermatofibrosarcoma protuberans (DFSP) is an uncommon infiltrative tumor of the dermis with characteristic cytogenetic features, specifically the translocation t(17;22)(q22;q13) which often manifests as a supernumerary ring chromosome r(17;22). The translocation results in the fusion of two genes, collagen type I alpha 1(COL1A1) and platelet‐derived growth factor B‐chain (PDGFB). The trunk and extremities are the anatomic sites of predilection for DFSP, whereas the vulva and groin are quite uncommon sites of involvement.