Exploiting the nephrotoxic effects of venom from the sea anemone, Phyllodiscus semoni, to create a hemolytic uremic syndrome model in the rat

Abstract

In the natural world, there are many creatures with venoms that have interesting and varied activities. Although the sea anemone, a member of the phylum Coelenterata, has venom that it uses to capture and immobilise small fishes and shrimp and for protection from predators, most sea anemones are harmless to man. However, a few species are highly toxic; some have venoms containing neurotoxins, recently suggested as potential immune-modulators for therapeutic application in immune diseases. Phyllodiscus semoni is a highly toxic sea anemone; the venom has multiple effects, including lethality, hemolysis and renal injuries. We previously reported that venom extracted from Phyllodiscus semoni induced acute glomerular endothelial injuries in rats resembling hemolytic uremic syndrome (HUS), accompanied with complement dysregulation in glomeruli and suggested that the model might be useful for analyses of pathology and development of therapeutic approaches in HUS. In this mini-review, we describe in detail the venom-induced acute renal injuries in rat and summarize how the venom of Phyllodiscus semoni could have potential as a tool for analyses of complement activation and therapeutic interventions in HUS.

Keywords: complement; complement regulators; hemolytic uremic syndrome; marine envenomation; renal failure; sea anemone.

Figure 1

Photographs of Phyllodiscus semoni (Unbachi-isogintyaku) and nematocysts. (A) The intact organism as found in the seas off Okinawa Island; (B) Close-up view of the globular vesicles (white arrows) with nematocysts. Scales bar is in the upper right corner of frame B. The underwater photos were taken by M. Mizuno.

Figure 2

Time course of renal pathology after injection of PsTX-T. A-1, B-1, C-1, D-1, E-1 and F-1 are glomeruli in cortex under 200× magnifications. A-2, B-2, C-2, D-2, E-2 and F-2 are glomeruli under 400× magnifications. A-3, B-3, C-3, D-3, E-3 and F-3 are tubuli in cortex under 200× magnifications. A-4, B-4, C-4, D-4, E-4 and F-4 are outer medulla under 200× magnifications. A-5, B-5, C-5, D-5, E-5 and F-5 are inner medulla under 200× magnifications. For light microscopic (LM) analyses, tissues were fixed in methacarn overnight and embedded in paraffin. Two-micrometer sections were stained with periodic acid-Schiff. Time course is noted across the top of the plates. Arrows indicate deposition of fibrin-like materials. Arrowheads indicate cellular proliferation. Scale bars are in the upper left corner of frames A-1 to A-5. Adapted from [76], Copyright © 2007, with permission from Elsevier.

Figure 3

Summary of time course of renal injuries, C3b/C5b-9 deposition and infiltration of inflammatory cells in glomeruli after intravenous injection of PsTX-T. Panel A summarises severity of renal injuries assessed under light microscopy and scored as -, no change, through +++ injury, scaled according to the number of affected glomeruli and area of tubular injuries: -, no change; +/-, minimal change; +, less than 25%; ++, between 25% and 75%; +++, widespread injury with severe damage involving over 75%. Panels B and C summarise degrees of C3 deposition and membrane attack complex (MAC; C5b-9) deposition in glomeruli of the kidney after PsTX-T administration; the degree of deposition of C3b or C5b-9 was scored as −, negative, through +++ according to the positive staining area: −, negative staining; +/−, minimal staining; +, positive staining less than 25%; ++, between 25% and 50%; +++, more than 50%. Panel D shows total number of infiltrating inflammatory cell recognized as leukocyte common antigen (LCA)-positive cells and RP-3 positive neutrophils in glomeruli. Panel E shows time course of impaired renal function. Cre: creatinine, BUN: blood urea nitrogen. Each value is shown as mean ± SE.

Figure 4

Distribution of CD55 in glomeruli after PsTX-T injection. After administration of PsTX-T, binding of anti-CD55 was decreased at 6 h (B) and lowest between 24 h and 3 days (C and D). Expression of CD55 was restored in most of the glomeruli by 14 days after injection of PsTX-T (G). For immunohistological analysis, kidney was embedded in OCT compound (Sakura Finetechnical Co., Tokyo, Japan), snapfrozen in liquid nitrogen, cryostat-sectioned at 2 μm, and fixed with acetone for 10 min at room temperature. To investigate the expression of CD55, sections were incubated with anti-rat CD55 (clone; RD-III7) followed by fluorescenin isothiocyanate-labeled anti-rat CD55 as our previous report [76]. Original magnifications are shown in right bottom of each frame. Scale bars are in the upper right corner of frames A and F.