Effect of Russell's viper (Vipera russelli siamensis) venom on renal hemodynamics in dogs

Acute phase reactions in Daboia siamensis venom and fraction-induced acute kidney injury: the role of oxidative stress and inflammatory pathways in in vivo rabbit and ex vivo rabbit kidney models

Background

This study examines the direct nephrotoxic effects of Daboia siamensis venom (RVV) and venom fractions in in vivo and isolated perfused kidneys (IPK) to understand the role of inflammation pathways and susceptibility to oxidative stress in venom or fraction-induced acute renal failure.

Methods

We administered RVV and its venom fractions (PLA2, MP, LAAO, and PDE) to rabbits in vivo and in the IPK model. We measured oxidative stress biomarkers (SOD, CAT, GSH, and MDA) in kidney tissue, as well as inflammatory cytokines (TNF-α, IL-1β, IFN-γ, IL-4, IL-5, and IL-10), MDA and GSH levels in plasma and urine. We also calculated fractional excretion (FE) for pro-/anti-inflammatory cytokines and oxidative stress biomarkers, including the ratios of pro-/anti-inflammatory cytokines in urine after envenomation.

Results

In both kidney models, significant increases in MDA, SOD, CAT, and GSH levels were observed in kidney tissues, along with elevated concentrations of MDA and GSH in plasma and urine after injecting RVV and venom fractions. Moreover, RVV injections led to progressive increases in FEMDA and decreases in FEGSH. The concentrations of IL-4, IL-5, IL-10, IFN-γ, and TNF-α in plasma increased in vivo, as well as in the urine of the IPK model, but not for IL-1β in both plasma and urine after RVV administrations. Urinary fractional excretion of TNF-α, IL-1β, IFN-γ, IL-4, IL-5, and IL-10 tended to decrease in vivo but showed elevated levels in the IPK model. A single RVV injection in vivo disrupted the balance of urinary cytokines, significantly reducing either the TNF-α/IL-10 ratio or the IFN-γ/IL-10 ratio.

Conclusion

RVV induces renal tubular toxicity by increasing oxidative stress production and elevating inflammatory cytokines in urine. During the acute phase of acute kidney injury, the balance of urine cytokines shifts toward anti-inflammatory dominance within the first two hours post-RVV and venom fractions.

The pathophysiological effects of Russell's viper (Daboia siamensis) venom and its fractions in the isolated perfused rabbit kidney model: A potential role for platelet activating factor

The pathophysiological effects of Russell's viper venom (RVV) and its fractions, including phospholipase A₂ (RvPLA₂), metalloprotease (RvMP), L-amino acid oxidase (RvLAAO), and phosphodiesterase (RvPDE) on renal functions were investigated using the isolated perfused rabbit kidney (IPK) model. Moreover, whether their effects on renal alterations were promoted by platelet activating factor (PAF) was tested using the PAF receptor antagonist, WEB 2086. There was a marked reduction in the perfusion pressure (PP) and renal vascular resistance (RVR) 10 min after RVV administration (1.0 mg/100 ml of perfusate), thereafter both PP and RVR gradually increased and approached the control level within 90 min. These effects were abolished by pretreatment with WEB2086 (2 μg/μl). Administration with RvPLA₂ (280 μg/ml), RvMP (280 μg/ml), or RvLAAO (135 μg/ml) alone increased both the PP and RVR, whereas RvPDE (100 μg/ml) reduced both the PP and RVR. Pretreatment with WEB 2086 completely abolished the effects induced by RvMP, but not the other fractions. The RVV also caused a marked decrease in the glomerular filtration rate (GFR), urinary flow rate (UF), and osmolar clearance (Cosm), and these effects were not inhibited by pretreatment with WEB2086. Each RVV fraction also increased, to varying extents, the GFR, UF, and Cosm, and these effects induced by RvPLA₂ or RvMP, but not the other fractions, were completely blocked by WEB 2086. Changes in percent filtered Na⁺ and K⁺ excreted in the IPK by RVV, RvPDE, and RvMP were abolished by pretreatment with WEB 2086. Histological evaluation profiled mainly tubulonephrosis in the treated kidney. These results reveal that the alterations in renal functions induced by RVV and its fractions are due to the synergistic action of the different components of snake venom, instead of the action of a single component. The effects of RVV and its fractions in rabbit IPK are mediated at least in part by PAF.

Marine toxins and nephrotoxicity:Mechanism of injury

Marine toxins are known among several causes of toxin induced renal injury. Enzymatic mechanism by phospholipase A₂ is responsible for acute kidney injury (AKI) in sea snake envenoming without any change in cardiac output and systemic vascular resistance. Cnidarian toxins form pores in the cell membrane with Ca influx storm resulting in cell death. Among plankton toxins domoic acid, palytoxin and maitotoxin cause renal injury by ion transport into the cell through ion channels resulting in renal cell swelling and lysis. Okadaic acid, calyculin A, microcystin LR and nodularin cause AKI by serine threonine phosphatase inhibition and hyperphosphorylation with increased activity of Ca²⁺/calmodulin - dependent protein kinase II, increased cytosolic Ca²⁺, reactive oxygen species, caspase and P53. Renal injury by plankons is mostly subclinical and requires sensitive biomarker for diagnosis. In this respect repeated consumption of plankton toxin contaminated seafood is a risk of developing chronic renal disease. The subject deserves more clinical study and scientific attention.

Acute effect of Russell’s viper (Daboia siamensis) venom on renal tubular handling of sodium in isolated rabbit kidney

Background: The common complication in cases of poisoning by Russell’s viper (Daboia siamensis) venom (RVV) is acute renal failure, but the pathogenesis involved in the alteration of kidney function is still not well understood.

Objective: To clarify the role of RVV in the pathogenesis of renal damage, the present study examines the functional short-term alterations acutely induced by RVV in isolated perfused rabbit kidney.

Methods: Effects of RVV on renal tubular handling of sodium including mean perfusion pressure (PP), the renalvascular resistance (RVR), the glomerular filtration rate (GFR), the urinary flow (V) and osmolar clearance (Cosm) were studied in two groups of isolated perfused rabbit kidneys; each group had four isolated rabbit kidneys. RVV was added to the perfusion system to obtain the final concentration of 10 ⃞g/ml.

Results: Immediate decreases in PP and RVR caused by the venom were significantly apparent (p < 0.05) in the first 15 min after RVV administration. A gradual rise in both PP and RVR occurred 15 min after the initial reduction of the first phase, but its remained below pretreatment values. The GFR, V, and Cosm decreased significantly throughout experiments after venom perfusion (p < 0.05). The total fractional sodium excretion increased significantly after venom perfusion throughout experiments, while significant reductions (p < 0.05) of renal tubular handling of sodium were apparent for proximal absolute reabsorption of sodium and proximal fractional reabsorption of sodium including marked reductions of distal absolute reabsorption of sodium and distal fractional reabsorption of sodium of the venom treated kidney. Optical microscopy of treated kidney tissue showed acute tubular necrosis at the end of experiment.

Conclusion: The present study suggests that an administration of RVV in the isolated rabbit kidney causes direct acute nephrotoxicity and acute alterations of main functional parameters that are probably mediated by either the direct action of venom components or an indirect effect from vasoactive mediators released from renal cells of the RVV-treated kidney.

Effects of phospholipase A2 and metalloprotease fractions of Russell's viper venom on cytokines and renal hemodynamics in dogs

Several enzymes in Russell's viper (Daboia siamensis) venom are involved in the venom effects and renal injury. The effects of fractional components of Russell's viper venom, phospholipase A(2) and metalloprotease fractions, were examined in two groups of four experimental dogs each. Animals received an intravenous injection of 140 μg/kg of each venom fraction. The inflammatory effects and renal hemodynamic changes were assessed. Plasma concentrations of interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and PGE2 were elevated by both phospholipase A(2) (PLA(2)) and metalloprotease (MP) fractions. The plasma level of nitric oxide was increased after PLA(2) fraction injection but not with MP fraction injection. Leukocytosis with increase in lymphocytes, monocytes and granulocytes was observed after both PLA(2) and MP injections. Results from this study suggested that both PLA(2) and MP were inflammatory. Increased red blood cell count, hematocrit and hemoglobin concentration were observed in animals injected with PLA(2) fraction, but not with MP fraction. Hemodynamically, PLA(2) fraction induced marked decrease in mean arterial pressure with decreased renal vascular resistance initially followed later by increased renal vascular resistance. MP fraction caused less decrease of mean arterial pressure but increased renal vascular resistance throughout the experiment. Both enzymes decreased renal blood flow, glomerular filtration rate and urine flow. The findings indicate vasodilating effect of PLA(2) fraction and vasoconstricting effect and decreased cardiac function of MP fraction.

Effect of purified Russell's viper venom-factor X activator (RVV-X) on renal hemodynamics, renal functions, and coagulopathy in rats

Acute renal failure (ARF) is the most frequent and a serious complication in victims of Russell's viper snakebites. Russell's viper venom-factor X activator (RVV-X) has been identified as a main procoagulant enzyme involving coagulopathy, which might be responsible for changes in renal hemodynamics and renal functions. Here, we purified RVV-X from crude Russell's viper venom to study renal hemodynamics, renal functions, intravascular clot, and histopathological changes in Sprague-Dawley rats. Changes in renal hemodynamics and renal functions were evaluated by measuring the mean arterial pressure, glomerular filtration rate (GFR), effective renal plasma flow (ERPF), effective renal blood flow (ERBF), renal vascular resistance (RVR), and fractional excretion of electrolytes. After 10 min, rats receiving both crude venom and purified RVV-X decreased GFR, ERPF, and ERBF and increased RVR. These changes correlated to renal lesions. Along with the determination of intravascular clot, rats injected with purified RVV-X increased the average D-dimer level and reached a peak at 10 min, declined temporarily, and then reached another peak at 30 min. The temporal association between clots and renal dysfunction was observed in rats within 10 min after the injection of purified RVV-X. These findings suggested RVV-X as a major cause of renal failure through intravascular clotting in the renal microcirculation.

Effects of Bungarus candidus (Malayan krait) venom on general circulation and renal hemodynamics in experimental animals

Background: Many studies have reported the occurrence of lethal acute renal failure after snakebites. Bungarus candidus (Malayan krait) is a medically important venomous snake distributed widely throughout Southeast Asia. The best known features of systemic envenoming by B. candidus are neurotoxic. Objective: Obtain more information on effects of B. candidus venom on changes in systemic and renal hemodynamics in experimental animals. Methods: Twelve adult male New Zealand white rabbits were used to study the effect of B. candidus venom on general circulation and renal hemodynamics. An anesthetized animal was intravenously injected with B. candidus venom at a dosage of 50μg/kg bodyweight. All changes of parameters were observed after initial post venom injection and recorded at 30 min intervals until 150 minutes after envenomation. Results: After envenomation, cardiovascular responses showed a marked decrease in mean arterial pressure within two minutes, afterwards gradually returning closely to baseline values. There were stepwise decreases in heart rate and cardiac output, while total peripheral resistance was slightly increased. The renal hemodynamics significantly decreased by glomerular filtration rate, effective renal plasma flow and effective renal blood flow, while the filtration fraction significantly increased. Envenomed animals showed a reduction in renal fraction, while renal vascular resistance stepwise increased. The plasma potassium level tended to increase. Animals showed stepwise decreases in urinary excretion of Na+, K+ and Cl-. A marked decrease in plasma calcium level was apparent at 120 minutes, while plasma creatine phosphokinase and lactate dehydrogenase levels increased at 30-120 minutes. Conclusion: A significant drop in blood pressure was attributed to a sustained fall in cardiac output, which would be associated with a reduction in heart rate. Sustained hypotension would contribute to reduction of renal blood flow, which results in decreased GFR.

Snakebite nephrotoxicity in Asia

Snakebites have the highest incidence in Asia and represent an important health problem. Clinical renal manifestations include proteinuria, hematuria, pigmenturia, and renal failure. Nephropathy usually is caused by bites by snakes with hemotoxic or myotoxic venoms. These snakes are Russell's viper, saw-scaled viper, hump-nosed pit viper, green pit viper, and sea-snake. Renal pathologic changes include tubular necrosis, cortical necrosis, interstitial nephritis, glomerulonephritis, and vasculitis. Hemodynamic alterations caused by vasoactive mediators and cytokines and direct nephrotoxicity account significantly for the development of nephropathy. Hemorrhage, hypotension, disseminated intravascular coagulation, intravascular hemolysis, and rhabdomyolysis enhance renal ischemia leading to renal failure. Enzymatic activities of snake venoms account for direct nephrotoxicity. Immunologic mechanism plays a minor role.

Effects of Russell's viper venom fractions on systemic and renal hemodynamics

Changes in systemic and renal hemodynamics induced by Russell's viper venom are well established. The component of the venom responsible for hemodynamic alteration has not been identified. By Sephadex column chromatography five fractions of Russell's viper (Daboia russellii siamensis) venom were isolated. Each venom fraction consisted of phospholipase A2, proteolytic enzyme, phosphomonoesterase, phosphodiesterase, arginine ester hydrolase and hyaluronidase of varying activities. Hemodynamic effects of each venom fraction including mean arterial pressure, cardiac output, systemic and renal vascular resistance, renal blood flow and glomerular filtration rate were studied in five groups of dogs; each group had four dogs. Minimal hemodynamic changes were observed in dogs receiving venom fraction I. Increased renal vascular resistance with diminution of renal blood flow and glomerular filtration rate was observed in dogs receiving venom fractions II, III, IV and V. A markedly increased renal vascular resistance with maximal decrease in renal blood flow and glomerular filtration rate was caused by fraction III of the venom with highest PLA2 and proteolytic enzyme activities. However, renal hemodynamic changes appeared to correlate better with proteolytic enzyme activity than PLA2 activity. The findings suggested the proteolytic enzyme as an important determinant of hemodynamic alteration. Fractional excretion of Na was increased in dogs injected with venom fraction IV, and is presumed to be due to the inhibition of tubular reabsorption of Na by a natriuretic factor in this venom fraction.

Snakebite nephropathy (Review Article)

There is a broad clinical spectrum of renal involvement in snakebite. Besides the local and systemic symptoms, clinical renal manifestations vary from mild proteinuria, haematuria, pigmenturia to acute renal failure. Bites by haemotoxic snakes and myotoxic snakes are the common causes of renal involvement especially acute renal failure. Therefore, renal failure is often associated with haemorrhagic diathesis, intravascular haemolysis and rhabdomyolysis. Renal pathological changes include mesangiolysis, glomerulonephritis, vasculitis, tubular necrosis, interstitial nephritis and cortical necrosis. Tubular necrosis is an important pathological counterpart of acute renal failure. Haemodynamic alterations induced by cytokines and vasoactive mediators leading to renal ischaemia are important in the pathogenesis of acute renal failure. Haemolysis, intravascular coagulation and rhabdomyolysis are important contributing factors. Direct nephrotoxicity can be induced by the venom through metalloproteases and phosphilipase A2. Immunologic mechanism plays a minor role in the pathogenesis of the renal lesion.

Histopathological changes induced by the venom of the snake Vipera raddei (Armenian adder)

The venom of the Armenian adder (Vipera raddei Boettger, 1890) was tested for its ability to induce histopathological changes in rabbits after long-term (once every 6 days for 30 days) intramuscular injection of the venom (0.35 mg/kg approx. 0.5 LD 50), by light microscopic examination of some organs (liver, heart, kidney, adrenal, lung, spleen). V. raddei (Vr) venom induces changes including necrosis and edematous appearance with cellular infiltration and vacuolation. The injury of kidneys includes significant changes of the glomerular apparatus. Lung sections showed infiltration of erythrocytes within bronchial alveoli and dilation of bronchi. Liver sections showed vascular damage, significant quantities of hemosiderin and also presence of lymphohistiocyte elements. In the heart, Armenian adder venom produced slight disruption of the structure of cardiomyocytes, fibrosis and congestion of blood vessels. The histological structure of the spleen was not disturbed by the venom but there were lymphoblasts and numerous polynuclear macrophages within the central zone of follicules, which may indicate a development of moderate inflammatory reactions and activation of the complement system. Our results suggest that the venom of V. raddei induces moderate histopathological changes in vital organs.

Renal ischaemia, transient glomerular leak and acute renal tubular damage in patients envenomed by Russell's vipers (Daboia russelii siamensis) in Myanmar

Fifty-two patients who had been bitten by Russell's vipers in Myanmar developed acute renal failure (serum creatinine exceeding 1.3 mg/dL). Thirty-four of them (65%) became oliguric, but the other 18 (35%) maintained a urine output of more than 400 mL/24 h. In oliguric patients, gastrointestinal haemorrhages, renal angle tenderness and conjunctival oedema occurred more commonly, and peak serum creatinine, blood urea nitrogen and the fractional excretion of sodium were significantly higher (P < 0.01) than in non-oliguric patients, indicating a greater degree of renal damage. Urinary concentrations of beta 2 microglobulin and retinol binding protein were raised in most of the patients indicating failure of proximal tubular reabsorption of these proteins, while high urinary N-acetyl glucosaminidase concentrations were consistent with renal tubular damage. Plasma concentrations of active renin were very high, suggesting that renal ischaemia, associated with activation of the renin-angiotensin system, was involved in the development of renal dysfunction.

Development of renal function abnormalities following bites by Russell's vipers (Daboia russelii siamensis) in Myanmar

Renal function was monitored in 24 patients with systemic envenoming following proven Russell's viper bite. In all patients, blood clotted within 20 min on admission. In 15 cases severe defibrination (systemic envenoming) developed during the next 3-5 d. None of the patients received antivenom before admission but enzyme-refined monospecific antivenom was given to those who developed signs of systemic envenoming. Specific antigen was detected by enzyme immuno-assay in all 21 subjects tested. Nine patients whose renal function remained normal did not develop systemic envenoming, and recovered without any treatment even though venom antigen was detectable in their serum. Ten patients developed mild renal dysfunction and systemic envenoming, but recovered after treatment with antivenom alone. The remaining 5 patients, all of whom were oliguric from admission, developed acute renal failure despite treatment with antivenom, but some recovered after peritoneal dialysis. Serum venom antigen levels were high in the last 2 groups, but there was some overlap. Albuminuria, found only in patients who became systemically envenomed, was associated with high fractional sodium excretion in those who developed acute oliguric renal failure. Albuminuria may appear before a gross clotting defect is detectable. It is an indication for antivenom and spot measurements might prove a useful early predictor of outcome.

Acute effect of Russell's viper (Vipera russelli siamensis) venom on renal hemodynamics and autoregulation of blood flow in dogs

Renal hemodynamics and autoregulation of blood flow were investigated following intravenous injection of Russell's viper venom (0.1 mg/kg) in dogs anesthetized with sodium pentobarbital. After venom injection, the glomerular filtration rate fell significantly throughout the experimental period of three hr. Urine flow rate and renal blood flow also decreased and the filtered load of electrolytes declined significantly. The fractional excretion of sodium, potassium and phosphorus increased following venom administration. These data suggest that the venom may depress both glomerular and tubular functions. The renal autoregulation of blood flow was maintained during the experimental reduction of renal arterial pressure. We conclude that the ability of renal vasculature to autoregulate renal blood flow is not inhibited by Russell's viper venom, even though renal function is depressed.