Miroslav Sekulic

A Compendium of Urinary Biomarkers Indicative of Glomerular Podocytopathy

It is well known that glomerular podocyte injury and loss are present in numerous nephropathies and that the pathophysiologic consecution of disease hinges upon the fate of the podocyte. While multiple factors play a hand in glomerulopathy progression, basic logic lends that if one monitors the podocytes status, that may reflect the status of disease. Recent investigations have focused on what one can elucidate from the noninvasive collection of urine, and have proven that certain, specific biomarkers of podocytes can be readily identified via varying techniques. This paper has brought together all described urinary biomarkers of podocyte injury and is made to provide a concise summary of their utility and testing in laboratory and clinical theatres. While promising in the potential that they hold as tools for clinicians and investigators, the described biomarkers require further comprehensive vetting in the form of larger clinical trials and studies that would give their value true weight. These urinary biomarkers are put forth as novel indicators of glomerular disease presence, disease progression, and therapeutic efficacy that in some cases may be more advantageous than the established parameters/measures currently used in practice.

Angiotensin II regulates NOS expression in afferent arterioles of the developing porcine kidney.

NO protection is crucial against angiotensin II (ANG II) mediated vasoconstriction in postnatal preglomerular resistance vessels. Although whole kidney NOS is developmentally regulated, NOS regulation in developing renal resistance vessels is unknown. The hypothesis was NOS expression and function in developing afferent arterioles are regulated by ANG II through AT1 and AT2 receptors. Afferent arterioles from porcine kidneys, ages newborn, 7, 21 d, and adult, were dissected using a polybead perfusion technique. Dissected afferent arterioles were treated with ANG II and with either the AT1 receptor inhibitor candesartan or the AT2 receptor inhibitor PD 123319 and evaluated for NOS isoform expression and NOS enzymatic activity. Although NOS activity and neuronal NOS (nNOS) expression were greater in the newborn than in the adult, endothelial NOS (eNOS) expression was greater in the adult. ANG II increased NOS activity and eNOS expression at all ages, but nNOS expression only in developing afferents. AT1 and AT2 receptor blockade significantly attenuated NOS activity and eNOS expression at all ages, but nNOS expression only in developing afferents. ANG II regulates nNOS and eNOS expression and NOS activity in afferent arterioles of the developing kidney via AT1 and AT2 receptors.

Neuronal nitric oxide synthase, nNOS, regulates renal hemodynamics in the postnatal developing piglet

Introduction:Nitric oxide (NO) vasodilation critically modulates renal hemodynamics in the neonate compared with the adult. Based on the postnatal expression pattern of renal neuronal nitric oxide synthase (nNOS), the hypothesis was that nNOS is the major NOS isoform regulating renal hemodynamics in the immature, but not mature, kidney.Results:NOS inhibitors did not alter mean arterial pressure (MAP) in either group. Intrarenal S-methyl-L-thiocitrulline (L-SMTC) in newborns significantly reduced renal blood flow (RBF) 38 ± 4%, glomerular filtration rate (GFR) 42 ± 6%, and increased renal vascular resistance (RVR) 37 ± 7%, whereas intrarenal L-nitro-arginine methyl ester (L-NAME) affected RBF, GFR, and RVR equivalent to L-SMTC treatment. When L-NAME was administered after L-SMTC treatment, newborn renal hemodynamic changes were not further altered from what was observed when L-SMTC was administered alone. In contrast, in the adult, only intrarenal L-NAME, and not L-SMTC, affected renal hemodynamic responses.Discussion:In conclusion, these studies demonstrate that nNOS is an important regulator of renal hemodynamics in the newborn kidney, but not in the adult.Methods:Experiments compared renal hemodynamic responses with intrarenal infusion of L-NAME, an inhibitor of all NOS isoforms, with the selective nNOS inhibitor L-SMTC in the newborn piglet and the adult pig.

Rheological Influence Upon the Glomerular Podocyte and Resultant Mechanotransduction

The glomerular podocyte is exposed to numerous mechanical forces as a constituent of the glomerular filtration apparatus. This includes fluid shear stress (FSS) displaced upon the podocytic foot processs apical, lateral, and basal surfaces. Even in the face of continuous flow the podocyte is capable of contributing to physiologic filtration, however with pathologic levels of hyperfiltration there is increased FSS placed upon the cell. The mechanisms by which the podocyte detects and responds to FSS are topics of recent investigations, with the aim to clarify the way these cells are injured and/or adapt in times of hyperfiltration and disease states. As the pathogenesis of numerous glomerulopathies is contingent on the status of the podocyte, understanding the manner that these cells can be modified by FSS is essential. Likewise, determination of the effect of such mechanical forces upon other resident cells of the renal corpuscle would reveal the contribution of FSS in the progression of glomerular diseases. The biochemical manner in which podocytes sense and respond to FSS, that is mechanotransduction, will be discussed.

Parenchymal infiltration and lymphoma-associated membranoproliferative pattern of glomerular injury: an unusual presentation of mantle cell lymphoma.

Lymphomatous processes have been shown to involve the kidney by direct and paraneoplastic mechanisms. Direct injury can manifest by effacement of typical parenchymal architecture by the lymphomatous infiltrate, and indirect, paraneoplastic mechanisms have been associated with a variety of glomerular lesions. Mantle cell lymphoma (MCL) has rarely been reported to be associated with both direct infiltration and/ or paraneoplastic glomerular lesions. We describe a patient with rapidly progressive glomerulonephritis whose renal biopsy showed effacement of the renal parenchyma by MCL and a membranoproliferative pattern of glomerular injury. The patients bone marrow was also involved by MCL, and serology revealed small M-spikes and a positive rheumatoid factor. The clinicopathologic findings were consistent with a membranoproliferative pattern of glomerular injury secondary to MCL with infiltrative destruction of renal parenchyma. This case is unusual in that MCL was diagnosed on renal biopsy, that there was a two-pronged mechanism of renal injury, and that there were two separate monoclonal immunoglobulins elaborated by the lymphoma that could be associated with the glomerular injury. Although it is uncommon to make an initial diagnosis of lymphoma from a renal biopsy, it should be recognized that patients with lymphoma might develop clinically significant renal sequelae secondary to both direct and indirect mechanisms of lymphoma-mediated nephropathy.

Kidney Biopsy Yield: An Examination of Influencing Factors

Kidney biopsies are conducted under varying scenarios, presenting variables that could potentially influence yield and adequacy of tissue collected. We retrospectively reviewed 636 native and allograft kidney biopsies, and compared tissue collected between differing practitioners performing the biopsy (nephrologists or radiologists), imaging modalities for guidance (ultrasound or computed tomography), gauge needle used (18 or 16 G), and between on-site evaluators of biopsy adequacy conducted at the time of biopsy (general pathologists, renal pathologists, nephrologists). For radiologists using ultrasound guidance and 18 G needles, those using on-site evaluation of adequacy collected more glomeruli and glomeruli per length of tissue core than those not using on-site evaluation. Radiologists not using on-site evaluation but who used a larger bore needle (16 vs. 18 G) could generally collect comparable tissue as other biopsy performers who used on-site evaluation. Radiologists performing ultrasound-guided biopsies with 18 G needles without on-site evaluation consistently provided poorer tissue yield and had a higher rate of providing insufficient tissue so that a diagnosis could not be rendered. Nephrologists collected less total length of tissue cores, glomeruli, and arteries per case (whether performing the biopsy and/or performing on-site adequacy) compared with other groups using on-site evaluation, however, providing comparable density of glomeruli and arteries. Complication rates did not differ between compared groups using 18 G needles. It is our observation that the various conditions by which a kidney biopsy is obtained influences the yield of tissue collected and the subsequent ability for a pathologist to effectively provide a diagnosis.

Kidney dysfunction in the low-birth weight murine adult: implications of oxidative stress

Maternal undernutrition (MUN) during pregnancy leads to low-birth weight (LBW) neonates that have a reduced kidney nephron endowment and higher morbidity as adults. Using a severe combined caloric and protein-restricted mouse model of MUN to generate LBW mice, we examined the progression of renal insufficiency in LBW adults. Through 6 mo of age, LBW males experienced greater albuminuria (ELISA analysis), a more rapid onset of glomerular hypertrophy, and a worse survival rate than LBW females. In contrast, both sexes experienced a comparable progressive decline in renal vascular density (immunofluorescence analysis), renal blood flow (Laser-Doppler flowmetry analysis), glomerular filtration rate (FITC-sinistrin clearance analysis), and a progressive increase in systemic blood pressure (measured via tail-cuff method). Isolated aortas from both LBW sexes demonstrated reduced vasodilation in response to ACh, indicative of reduced nitric oxide bioavailability and endothelial dysfunction. ELISA and immunofluorescence analysis revealed a significant increase of circulating reactive oxygen species and NADPH oxidase type 4 (NOX4) expression in both LBW sexes, although these increases were more pronounced in males. Although more effective in males, chronic tempol treatment did improve all observed pathologies in both sexes of LBW mice. Chronic NOX4 inhibition with GKT137831 was more effective than tempol in preventing pathologies in LBW males. In conclusion, despite some minor differences, LBW female and male adults have a reduced nephron endowment comparable with progressive renal and vascular dysfunction, which is associated with increased oxidative stress and subsequent endothelial dysfunction. Tempol treatment and/or NOX4 inhibition attenuates renal and vascular dysfunction in LBW adults.

Pancreatic involvement by metastasizing neoplasms as determined by endoscopic ultrasound-guided fine needle aspiration: A clinicopathologic characterization

Pancreatic tumors often represent primary neoplasms, however organ involvement with metastatic disease can occur. The use of endoscopic ultrasound‐guided fine needle aspiration (EUS‐FNA) to determine the underlying pathology provides guidance of clinical management.

Nodular fasciitis of the vulva: a challenging histopathologic diagnosis supported by the detection of USP6 gene rearrangement.

Nodular fasciitis involving the vulva on physical examination can mimic a Bartholin gland lesion, and histologically can have overlapping features with more ominous mesenchymal pathologies. We describe a case in which a 52‐year‐old perimenopausal woman presents with a vulvar mass. After an initial biopsy and later excision, the myofibroblastic lesion was noted to have areas of differing cellularity, with compact nodule formations at the periphery. Immunohistochemical staining showed lesional cells to be positive for desmin, estrogen receptor, progesterone receptor, and smooth muscle actin, and negative for CD34, ALK‐1, myogenin, caldesmon, S100, and wide spectrum (Oscar) cytokeratin. Desmin is generally negative in this lesion type, but the positivity in this case was considered to be secondary to the origin of the myofibroblastic cells of the vulva. The morphologic pattern and immunophenotype favored a diagnosis of nodular fasciitis, however, the degree of hypercellularity and desmin positivity warranted further analysis. The diagnosis was supported with fluorescence in situ hybridization that demonstrated USP6 gene rearrangement. This highlights the necessity in certain challenging cases for ancillary molecular and/or cytogenetic analysis.

Disseminated peritoneal leiomyomatosis postmorcellated resection of uterine leiomyomatous tissue.

In a retrospective review, we identified six cases of disseminated peritoneal leiomyomatosis (DPL) that occurred after resection for uterine leiomyoma(ta) using a morcellation procedure between 2010 and 2016. DPL occurred in less than 1% of all patients who underwent a prior hysterectomy with morcellation, and DPL never occurred without having underwent such a resection. The median age of women at the time of their original resection of uterine tissue was 38.6 years; the median time interval until resection of DPL after the primary morcellation procedure was 73 months and the median age was 48 years. At the time of DPL resection, a median of 6.5 individual lesions was present per patient, with each lesion having a median size of 1.2 cm in the greatest dimension. The most common peritoneal sites of involvement included the sigmoid colon serosa, right pelvis/pelvic side wall, and anterior abdominal parietal peritoneum. The same parameters are described for previously reported cases of DPL in the literature developing after a morcellated resection of uterine leiomyoma(ta). The use of morcellating hysterectomy specimens with leiomyomata may lead to the development of DPL by seeding, may involve numerous peritoneal sites, and often presents 2 years after the original resection.