Ultrastructural Evidence for Direct Renal Infection with SARS-CoV-2

BackgroundA significant fraction of patients with coronavirus disease 2019 (COVID-19) display abnormalities in renal function. Retrospective studies of patients hospitalized with COVID-19 in Wuhan, China, report an incidence of 3%–7% progressing to ARF, a marker of poor prognosis. The cause of the renal failure in COVID-19 is unknown, but one hypothesized mechanism is direct renal infection by the causative virus, SARS-CoV-2.MethodsWe performed an autopsy on a single patient who died of COVID-19 after open repair of an aortic dissection, complicated by hypoxic respiratory failure and oliguric renal failure. We used light and electron microscopy to examine renal tissue for evidence of SARS-CoV-2 within renal cells.ResultsLight microscopy of proximal tubules showed geographic isometric vacuolization, corresponding to a focus of tubules with abundant intracellular viral arrays. Individual viruses averaged 76 µm in diameter and had an envelope studded with crown-like, electron-dense spikes. Vacuoles contained double-membrane vesicles suggestive of partially assembled virus.ConclusionsThe presence of viral particles in the renal tubular epithelium that were morphologically identical to SARS-CoV-2, and with viral arrays and other features of virus assembly, provide evidence of a productive direct infection of the kidney by SARS-CoV-2. This finding offers confirmatory evidence that direct renal infection occurs in the setting of AKI in COVID-19. However, the frequency and clinical significance of direct infection in COVID-19 is unclear. Tubular isometric vacuolization observed with light microscopy, which correlates with double-membrane vesicles containing vacuoles observed with electronic microscopy, may be a useful histologic marker for active SARS-CoV-2 infection in kidney biopsy or autopsy specimens.

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Integrin receptors in renal tubular epithelium: new insights into pathophysiology of acute renal failure

AJP Renal Physiology ◽

10.1152/ajprenal.1993.264.1.f1 ◽

1993 ◽

Vol 264 (1) ◽

pp. F1-F8 ◽

Cited By ~ 8

Author(s):

M. S. Goligorsky ◽

W. Lieberthal ◽

L. Racusen ◽

E. E. Simon

Keyword(s):

Renal Failure ◽

Acute Renal Failure ◽

Epithelial Cells ◽

Apical Surface ◽

Tubular Epithelium ◽

Tubular Epithelial Cells ◽

Renal Tubular Epithelial Cells ◽

Integrin Receptors ◽

Renal Tubular Epithelium ◽

Renal Tubular

This review summarizes the existing evidence implicating disordered adhesion of renal tubular epithelial cells to the basement membrane in the pathophysiology of acute renal failure. The following three major lines of investigation are discussed: 1) exfoliation of renal tubular epithelial cells as a potential mechanism of tubular obstruction, 2) normal distribution of integrin receptors along the tubular apparatus, and 3) redistribution of integrin receptors and remodeling of the cytoskeleton following acute injury to renal tubular epithelium. We advance the hypothesis that the loss of the basolateral expression of integrin receptors is responsible for the exfoliation of viable proximal epithelial cells and that the redistribution of integrin receptors from the basolateral to the apical surface of epithelial cells facilitates adhesion of detached cells to the in situ cells. These two processes culminate in tubular obstruction.

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Histomorphology and Immunohistochemistry of a Congenital Nephromegaly Demonstrate Concurrent Features of Heritable and Acquired Cystic Nephropathies in a Girgentana Goat (Capra falconeri)

Case Reports in Veterinary Medicine ◽

10.1155/2021/8749158 ◽

2021 ◽

Vol 2021 ◽

pp. 1-8

Author(s):

Christian Mayer ◽

Steffen Ormanns ◽

Monir Majzoub-Altweck

Keyword(s):

Kidney Diseases ◽

Renal Tissue ◽

Renal Parenchyma ◽

Biliary Duct ◽

Differentiation Markers ◽

Mesenchymal Transition ◽

Tissue Sections ◽

Renal Tubular Epithelium ◽

First Case ◽

Renal Tubular

Polycystic kidney diseases (PKD) represent frequent congenital and adult nephropathies in humans and domestic animals. This report illustrates an uncommon state of congenital PKD in a girgentana goat (Capra falconeri). A stillborn female goat kid was submitted for postmortem examination and underwent macroscopic and microscopic examination. The kidneys showed a bilateral nephromegaly and a perpendicular polycystic altered texture of the renal parenchyma. Renal tissue sections were comprehensively investigated by histopathology (overview and special stains), immunohistochemistry (CD10, CD117, pan-cytokeratin, cytokeratin 7, E-cadherin, Pax2, Pax8, and vimentin), and electron microscopy (SEM, TEM). Histopathology of renal tissue sections revealed polycystic alterations of the renal parenchyma as well as conspicuous polypoid proliferates/projections of the renal tubular epithelium, which showed clear cell characteristics. Furthermore, epithelial projections were indicative for epithelio-mesenchymal-transition, cellular depolarization, and strong expression of differentiation markers Pax2, Pax8, and CD10. Ultrastructural morphology of the projections was characterized by numerous diffusely distributed, demarked round cytoplasmic structures and several apico-lateral differentiations. Additionally, hepatic malformations comprising biliary duct proliferation with saccular dilation and bridging fibrosis were observed. Notably, this report describes the first case of a congenital cystic nephropathy with overlapping features of heritable and acquired nephropathies in any species. Epithelio-mesenchymal-transition and altered cadherin expression seem to be crucial components of a suspected pathomechanism during cystogenesis.

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CO2 equilibria in renal tissue

AJP Renal Physiology ◽

10.1152/ajprenal.1980.239.4.f307 ◽

1980 ◽

Vol 239 (4) ◽

pp. F307-F318 ◽

Cited By ~ 1

Author(s):

Gerhard Malnic

Keyword(s):

Carbonic Acid ◽

Water Layer ◽

Renal Tissue ◽

Buffer System ◽

Renal Tubules ◽

Tubular Epithelium ◽

Renal Tubular Epithelium ◽

Arterial Blood ◽

Disequilibrium Ph ◽

Renal Tubular

Disequilibrium situations within the bicarbonate/CO2 buffer system have been observed in the kidney. On the one hand, a Pco2 difference between final urine and arterial blood has been detected. On the other, a disequilibrium pH was found in cortical renal tubules and attributed to either increased carbonic acid concentrations or to Pco2 levels above those of arterial blood. Recent methodological developments have yielded better insight into these disequilibrium situations. They include, besides the use of pH microelectrodes, the introduction of microcalorimetric total CO2 determinations and Pco2 microelectrodes. There is agreement concerning the finding of a Pco2 10–40 mmHg above that in arterial blood in renal cortical tubules; however, stellate vessel Pco2 equal to tubular Pco2 was found by only one group of investigators. According to their view, diffusion equilibrium exists between all cortical structures, a finding disputed by others using a similar methodology. CO2 permeability of tubular epithelium is also still controversial, with values ranging from one-half (microcalorimetric method) to one-twentieth (pH-equilibration method) of an equivalent water layer having been reported. Two positions emerge on the basis of recent experimental results: the existence of very high permeability to CO2 and consequent diffusion equilibrium in renal cortex, and the occurrence of CO2 diffusion limitation leading to the establishment of finite Pco2 gradients across renal tubular epithelium. disequilibrium pH; CO2 permeability; tubular Pco2; CO22 fluxes; carbonic anhydrase

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Convergent use of phosphatidic acid for Hepatitis C virus and SARS-CoV-2 replication organelle formation

10.1101/2021.05.10.443480 ◽

2021 ◽

Author(s):

Keisuke Tabata ◽

Vibhu Prasad ◽

David Paul ◽

Ji-Young Lee ◽

Minh-Tu Pham ◽

...

Keyword(s):

Hepatitis C Virus ◽

Hepatitis C ◽

Phosphatidic Acid ◽

Rna Viruses ◽

Light And Electron Microscopy ◽

Membrane Vesicles ◽

Double Knockout ◽

Double Membrane ◽

Targeting Therapy ◽

Alternative Pathways

Double membrane vesicles (DMVs) are used as replication organelles by phylogenetically and biologically distant pathogenic RNA viruses such as hepatitis C virus (HCV) and severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Viral DMVs are morphologically analogous to DMVs formed during autophagy, and although the proteins required for DMV formation are extensively studied, the lipids driving their biogenesis are largely unknown. Here we show that production of the lipid phosphatidic acid (PA) by acylglycerolphosphate acyltransferase (AGPAT) 1 and 2 in the ER is important for DMV biogenesis in viral replication and autophagy. Using DMVs in HCV-replicating cells as model, we found that AGPATs are recruited to and critically contribute to HCV replication and DMV formation. AGPAT1/2 double knockout also impaired SARS-CoV-2 replication and the formation of autophagosome-like structures. By using correlative light and electron microscopy, we observed the relocalization of AGPAT proteins to HCV and SARS-CoV-2 induced DMVs. In addition, an intracellular PA sensor accumulated at viral DMV formation sites, consistent with elevated levels of PA in fractions of purified DMVs analyzed by lipidomics. Apart from AGPATs, PA is generated by alternative pathways via phosphotidylcholine (PC) and diacylglycerol (DAG). Pharmacological inhibition of these synthesis pathways also impaired HCV and SARS-CoV-2 replication as well as formation of autophagosome-like DMVs. These data identify PA as an important lipid used for replication organelle formation by HCV and SARS-CoV-2, two phylogenetically disparate viruses causing very different diseases, i.e. chronic liver disease and COVID-19, respectively. In addition, our data argue that host-targeting therapy aiming at PA synthesis pathways might be suitable to attenuate replication of these viruses.

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The Response of Testis Cells to Low Dose X-Irradiation

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100099155 ◽

1981 ◽

Vol 39 ◽

pp. 542-543

Author(s):

D. E. Philpott ◽

W. Sapp ◽

C. Williams ◽

Joann Stevenson ◽

S. Black

Keyword(s):

Electron Microscopy ◽

Stem Cell ◽

Light Microscopy ◽

Dose Level ◽

Cross Sections ◽

Low Dose ◽

Light And Electron Microscopy ◽

Cellular Responses ◽

Post Irradiation ◽

X Irradiation

The response of spermatogonial cells to X-irradiation is well documented. It has been shown that there is a radiation resistent stem cell (As) which, after irradiation, replenishes the seminiferous epithelium. Most investigations in this area have dealt with radiation dosages of 100R or more. This study was undertaken to observe cellular responses at doses less than 100R of X-irradiation utilizing a system in which the tissue can be used for light and electron microscopy.Brown B6D2F1 mice aged 16 weeks were exposed to X-irradiation (225KeV; 15mA; filter 0.35 Cu; 50-60 R/min). Four mice were irradiated at each dose level between 1 and 100 rads. Testes were removed 3 days post-irradiation, fixed, and embedded. Sections were cut at 2 microns for light microscopy. After staining, surviving spermatogonia were identified and counted in tubule cross sections. The surviving fraction of spermatogonia compared to control, S/S0, was plotted against dose to give the curve shown in Fig. 1.

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Solving the mechanisms responsible for organelle behavior in vivo by same-cell correlative light and electron microscopy

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100120473 ◽

1992 ◽

Vol 50 (1) ◽

pp. 14-15

Author(s):

Conly L. Rieder

Keyword(s):

Electron Microscopy ◽

Quantitative Analysis ◽

Light Microscopy ◽

Living Cell ◽

Light And Electron Microscopy ◽

Time Behavior ◽

Dynamic Interactions ◽

Positive Identification ◽

Cellular Components

The behavior of many cellular components, and their dynamic interactions, can be characterized in the living cell with considerable spatial and temporal resolution by video-enhanced light microscopy (video-LM). Indeed, under the appropriate conditions video-LM can be used to determine the real-time behavior of organelles ≤ 25-nm in diameter (e.g., individual microtubules—see). However, when pushed to its limit the structures and components observed within the cell by video-LM cannot be resolved nor necessarily even identified, only detected. Positive identification and a quantitative analysis often requires the corresponding electron microcopy (EM).

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Development of an in vitro Model for the Study of the Response of Equine Tendon Fibroblasts to Injury and Medication

Veterinary and Comparative Orthopaedics and Traumatology ◽

10.1055/s-0038-1632561 ◽

1997 ◽

Vol 10 (01) ◽

pp. 6-11 ◽

Cited By ~ 3

Author(s):

R. F. Rosenbusch ◽

L. C. Booth ◽

L. A. Dahlgren

Keyword(s):

Electron Microscopy ◽

Extracellular Matrix ◽

Light Microscopy ◽

Light And Electron Microscopy ◽

Tendon Healing ◽

Matrix Proteins ◽

Isolated Cells ◽

Superficial Digital Flexor Tendon ◽

Vitro Model

SummaryEquine tendon fibroblasts were isolated from explants of superficial digital flexor tendon, subcultured and maintained in monolayers. The cells were characterized by light microscopy, electron microscopy and radiolabel studies for proteoglycan production. Two predominant cell morphologies were identified. The cells dedifferentiated toward a more spindle shape with repeated subcultures. Equine tendon fibroblasts were successfully cryopreserved and subsequently subcultured. The ability to produce proteoglycan was preserved.The isolated cells were identified as fibroblasts, based on their characteristic shape by light microscopy and ultrastructure and the active production of extracellular matrix proteins. Abundant rough endoplasmic reticulum and the production of extracellular matrix products demonstrated active protein production and export. Proteoglycans were measurable via liquid scintillation counting in both the cell-associated fraction and free in the supernatant. This model is currently being utilized to study the effects of polysulfated glycosaminoglycan on tendon healing. Future uses include studying the effects of other pharmaceuticals, such as hyaluronic acid, on tendon healing.A model was developed for in vitro investigations into tendon healing. Fibroblasts were isolated from equine superficial digital flexor tendons and maintained in monolayer culture. The tenocytes were characterized via light and electron microscopy. Proteoglycan production was measured, using radio-label techniques. The fibroblasts were cryopreserved and subsequently subcultured. The cells maintained their capacity for proteoglycan production, following repeated subculturing and cryopreservation.

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Aristolochic acid induces renal tubular injury and inhibits expression of bone morphogenetic protein-7 mRNA in renal tissue of rats

Journal of Chinese Integrative Medicine ◽

10.3736/jcim20080514 ◽

2008 ◽

Vol 6 (5) ◽

pp. 502-507 ◽

Cited By ~ 2

Author(s):

HL Wang

Keyword(s):

Bone Morphogenetic Protein ◽

Aristolochic Acid ◽

Renal Tissue ◽

Tubular Injury ◽

Bone Morphogenetic Protein 7 ◽

Morphogenetic Protein ◽

Renal Tubular

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Osteopontin expressed by renal tubular epithelium mediates interstitial monocyte infiltration in rats

AJP Renal Physiology ◽

10.1152/ajprenal.2000.278.1.f110 ◽

2000 ◽

Vol 278 (1) ◽

pp. F110-F121 ◽

Cited By ~ 30

Author(s):

Hirokazu Okada ◽

Kenshi Moriwaki ◽

Raghuram Kalluri ◽

Tsuneo Takenaka ◽

Hiroe Imai ◽

...

Keyword(s):

Target Genes ◽

Renal Plasma Flow ◽

Mrna Level ◽

Antisense Oligodeoxynucleotide ◽

Tubular Epithelium ◽

Rt Pcr ◽

Goodpasture Syndrome ◽

Renal Tubular Epithelium ◽

Protein Excretion ◽

Renal Tubular

In this study, we have shown that intravenously administered antisense oligodeoxynucleotide (ODN) was demonstrated to be taken up by tubular epithelium, after which it blocked mRNA expression of target genes in normal and nephritic rats. Therefore, we injected osteopontin (OPN) antisense ODN to Goodpasture syndrome (GPS) rats every second day between days 27 and 35, the time when renal OPN expression increased and interstitial monocyte infiltration was aggravated. In parallel to blockade of tubular OPN expression, this treatment significantly attenuated monocyte infiltration and preserved renal plasma flow in GPS rats at day 37, compared with sense ODN-treated and untreated GPS rats. No significant changes were observed in OPN mRNA level by RT-PCR and histopathology of the glomeruli after ODN treatment, which was compatible with an absence of differences in the urinary protein excretion rate. In conclusion, OPN expressed by tubular epithelium played a pivotal role in mediating peritubular monocyte infiltration consequent to glomerular disease.

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