Renal involvement in Russell's viper bite patients without disseminated intravascular coagulation

Acute kidney failure following severe viper envenomation: clinical, biological and ultrasonographic aspects

Background:

Acute kidney injury (AKI) is a frequent complication of snakebite envenomation, which is still little known in sub-Saharan Africa. This study aims to describe the clinical, biological and ultrasonographic aspects of AKI following severe snakebite envenomation managed in the intensive care unit.

Method:

A prospective observational survey was performed in Benin over a period of 18 months. All patients suffering severe snakebite envenomation (SBE) were included. The diagnosis of AKI was made using the KDIGO criteria. Kidney ultrasound exam was performed in all patients to assess internal bleeding and morphological and structural abnormalities of the kidneys.

Results:

Fifty-one cases of severe SBE were included. All patients presented inflammatory syndrome and showed abnormal WBCT whereas bleeding was found in 46 of them (90%). The median time to hospital presentation was three days. The majority of patients were male (M/F sex ratio = 1.55) and the median age was 26. Sixteen patients (31%) showed AKI according to the KDIGO criteria. Severe AKI (KDIGO stage 2 and 3) was observed in three patients, including one stage 2 and two stage 3. Kidney ultrasound revealed three cases of kidney capsular hematoma (6%), two cases of kidney hypertrophy (3%), three cases of kidney injury (4%), two stage 1 KDIGO and one stage 2 KDIGO. Only one patient benefited from hemodialysis. All patients showing AKI recovered without sequels. The median duration of hospital stays was four days. Seven patients died (14%) including four among the 16 AKI patients. Antivenom has been administered to 41 patients (80%). The comparison between patients without and with AKI did not show any significant difference except gender (p = 10^-2).

Conclusion:

AKI is a common complication of severe snakebite envenomation. Resulting from inflammatory and hemorrhagic disorders, AKI may prove to be a short-term life-threatening factor.

Bedside Coagulation Tests in Diagnosing Venom-Induced Consumption Coagulopathy in Snakebite

Venom-induced consumption coagulopathy is the most important systemic effect of snake envenoming. Coagulation tests are helpful to accurately and promptly diagnose venom-induced consumption coagulopathy and administer antivenom, which is the only specific treatment available. However, bedside clotting tests play a major role in diagnosing coagulopathy in low-income settings, where the majority of snakebites occur. We conducted a literature search in MEDLINE^® from 1946 to 30 November 2019, looking for research articles describing clinical studies on bedside coagulation tests in snakebite patients. Out of 442 articles identified, 147 articles describing bedside clotting assays were included in the review. Three main bedside clotting tests were identified, namely the Lee–White clotting test, 20-min whole blood clotting time and venous clotting time. Although the original Lee–White clotting test has never been validated for snake envenoming, a recently validated version has been used in some South American countries. The 20-min whole blood clotting time test is the most commonly used test in a wide range of settings and for taxonomically diverse snake species. Venous clotting time is almost exclusively used in Thailand. Many validation studies have methodological limitations, including small sample size, lack of case-authentication, the inclusion of a heterogeneous mix of snakebites and inappropriate uses of gold standard tests. The observation times for bedside clotting tests were arbitrary, without proper scientific justification. Future research needs to focus on improving the existing 20-min whole blood clotting test, and also on looking for alternative bedside coagulation tests which are cheap, reliable and quicker.

Acute Kidney Injury Induced by Bothrops Venom: Insights into the Pathogenic Mechanisms

Acute kidney injury (AKI) following snakebite is common in developing countries and Bothrops genus is the main group of snakes in Latin America. To evaluate the pathogenic mechanisms associated with Bothrops venom nephrotoxicity, we assessed urinary and blood samples of patients after hospital admission resulting from Bothrops snakebite in a prospective cohort study in Northeast Brazil. Urinary and blood samples were evaluated during hospital stay in 63 consenting patients, divided into AKI and No-AKI groups according to the KDIGO criteria. The AKI group showed higher levels of urinary MCP-1 (Urinary monocyte chemotactic protein-1) (median 547.5 vs. 274.1 pg/mgCr; p = 0.02) and urinary NGAL (Neutrophil gelatinase-associated lipocalin) (median 21.28 vs. 12.73 ng/mgCr; p = 0.03). Risk factors for AKI included lower serum sodium and hemoglobin levels, proteinuria and aPTT (Activated Partial Thromboplastin Time) on admission and disclosed lower serum sodium (p = 0.01, OR = 0.73, 95% CI: 0.57–0.94) and aPTT (p = 0.031, OR = 26.27, 95% CI: 1.34–512.11) levels as independent factors associated with AKI. Proteinuria showed a positive correlation with uMCP-1 (r = 0.70, p < 0.0001) and uNGAL (r = 0.47, p = 0.001). FE_Na (Fractional Excretion of sodium) correlated with uMCP-1 (r = 0.47, P = 0.001) and uNGAL (r = 0.56, p < 0.0001). sCr (serum Creatinine) showed a better performance to predict AKI (AUC = 0.85) in comparison with new biomarkers. FE_K showed fair accuracy in predicting AKI (AUC = 0.92). Coagulation abnormality was strongly associated with Bothrops venom-related AKI. Urinary NGAL and MCP-1 were good biomarkers in predicting AKI; however, sCr remained the best biomarker. FE_K (Fractional Excretion of potassium) emerged as another diagnostic tool to predict early AKI. Positive correlations between uNGAL and uMCP-1 with proteinuria and FE_Na may signal glomerular and tubular injury. Defects in urinary concentrations highlighted asymptomatic abnormalities, which deserve further study.

A novel heparin-dependent inhibitor of activated protein C that potentiates consumptive coagulopathy in Russell's viper envenomation

The activation of coagulation factors V and X by Russell's viper venom (RVV) has been implicated in the development of consumptive coagulopathies in severely envenomed patients. However, factor Va is prone to inactivation by activated protein C (APC), an important serine protease that negatively regulates blood coagulation. It is therefore hypothesized that APC may be down-regulated by some of the venom components. In this study, we managed to isolate a potent Kunitz-type APC inhibitor, named DrKIn-I. Using chromogenic substrate, DrKIn-I dose-dependently inhibited the activity of APC. Heparin potentiated the inhibition and reduced the IC(50) of DrKIn-I by 25-fold. DrKIn-I, together with heparin, also protected factor Va from APC-mediated inactivation. Using surface plasmon resonance, DrKIn-I exhibited fast binding kinetics with APC (association rate constant = 1.7 × 10(7) M(-1) s(-1)). Direct binding assays and kinetic studies revealed that this inhibition (K(i) = 53 pM) is due to the tight binding interactions of DrKIn-I with both heparin and APC. DrKIn-I also effectively reversed the anticoagulant activity of APC and completely restored the thrombin generation in APC-containing plasma. Furthermore, although the injection of either DrKIn-I or RVV-X (the venom factor X-activator) into ICR mice did not significantly deplete the plasma fibrinogen concentration, co-administration of DrKIn-I with RVV-X resulted in complete fibrinogen consumption and the deposition of fibrin thrombi in the glomerular capillaries. Our results provide new insights into the pathogenesis of RVV-induced coagulopathies and indicate that DrKIn-I is a novel APC inhibitor that is associated with potentially fatal thrombotic complications in Russell's viper envenomation.

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.

Ability of a small, basic protein isolated from Russell's viper venom (Daboia russelli russelli) to induce renal tubular necrosis in mice

Russell's viper venom (RVV) induced acute renal failure involves both direct and indirect nephrotoxic actions where the specific component/s are yet to be identified. A basic cytotoxin of 7.2kDa (RVV-7) has been identified as potential nephrotoxin. Autoradiographic experiments demonstrated that only RVV-7 among RVV toxins binds specifically to mice kidney membrane. Homogeneous preparation of RVV-7 confirmed its necrotic cell killing property having EC(50) of 4.79+/-3.28microM. Tissue distribution kinetics of RVV-7 in mice showed its higher localization in kidney compared to blood and liver. Role of inherent factor responsible for its localization in kidney was assessed after chemical inactivation of its cytotoxic activity. Cytotoxicity was neutralized by histidine modification but consequent alteration of in vivo distribution was insignificant. Classical concept of glomerular capillary wall (GCW) permselectivity barrier denotes that apart from size selectivity, GCW also restricts anionic proteins from filtration. Reducing the pI of RVV-7 by chemical manipulation of its surface positive charges resulted to decreased accumulation in kidney. Histological observations of kidney from mice treated in vivo with RVV-7 showed degenerated tubular epithelium. These findings indicate that basic character and small size of RVV-7 are favorable for its rapid accumulation in kidney leading to necrotic destruction of tubular epithelium.

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.

Pathology of renal diseases in the tropics

Renal diseases unique to the tropics are those that occur in association with infectious diseases including dengue hemorrhagic fever, typhoid fever, shigellosis, leptospirosis, lepromatous leprosy, malaria, opisthorchiasis, and schistosomiasis. These renal complications can be classified on the basis of their clinical and pathologic characteristics into acute transient reversible glomerulonephritis, chronic progressive irreversible glomerulonephritis, amyloidosis, and acute renal failure (ARF) resulting from acute tubular necrosis, acute tubulointerstitial nephritis, and thrombotic microangiopathy. Certain primary glomerular diseases including immunoglobulin (Ig) M nephropathy and focal segmental and global glomerulosclerosis are prevalent in some tropical countries. Renal complications of venomous snakebites also are common in the tropics. This article discusses and summarizes important works in the literature in respect to the clinical syndromes, pathologic features, and pathogenesis of tropical renal diseases both in humans and experimental animal models.