Biodistribution of a near infrared fluorophore-labeled anti Shiga toxin molecule by non-invasive in vivo optical imaging in mice

ANDREA L. BERENGENO; VANESA ZYLBERMAN; NATALIA R. SALVETTI; BELKIS MARELLI; SANTIAGO SANGUINETI; FACUNDO SALINAS; YANINA HIRIART; HUGO H. ORTEGA

Mar del Plata

Encuentro; Reunión conjunta SAIC SAI SAFIS 2018; 2018

Abstract:Hemolytic uremic syndrome (HUS) is a multisystemic disorder characterized by microangiopathic hemolytic anemia, thrombocytopenia and acute renal damage. Shiga toxin (Stx) producing Escherichia coli (STEC) O157:H7 is the most common serotype associated with HUS in children younger than 5 years old. Argentina has the highest incidence of HUS in the world. Recently a new treatment capable of neutralizing the toxic effect of Stx and its variants has been developed. The efficacy and potency against Stx1 and Stx2 of F(ab?)2 fragments from an equine antiserum were proved in preclinical models. Although the anti-Stx F(ab?)2 pharmacokinetic was shown to be similar to that of immunoglobulin derived molecules, the tissue distribution and bioaccumulation have not been described. Our objective was to evaluate the biodistribution of anti-Stx F(ab?)2 labeled with a NIR fluorophore using an in vivo optical imaging system in mice. The 800CW Protein Labeling Kit - HMW was utilized to label the anti-Stx and 5 BALB/cCmedc mice (25 days old) were treated with 10 mg/kg. At 0.5, 1, 2, 4, 6, 8, 12 and 24 h after inoculation images were acquired using the Pearl Trilogy Image System (LI-COR Biosciences) with Ex/Em setting at 785/820 nm. After in vivo imaging, animals were sacrificed. Ex vivo imaging after removal of brain, heart, lungs, liver, spleen, kidneys, stomach, intestines, adrenal glands, eyes, seminal vesicles, prostate and bladder was performed. In vivo fluorescence was observed in large vessels, liver and kidneys at 0.5 h after inoculation with a decrease intensity over time. Ex vivo localization of anti-Stx in liver and kidneys was confirmed. Fluorescence signal in bladder was detected. This distribution should be associated with a high vascularization of these organs. Our results demonstrate that in vivo imaging systems are a valuable technology to understand biodistribution and targeting of new therapeutic biological molecules in experimental models.