Characterisation of the vascular pathology in Sigmodon hispidus (Rodentia: Cricetidae) following experimental infection with Angiostrongylus costaricensis (Nematoda: Metastrongylidae)

BACKGROUND Angiostrongylus costaricensis is a nematode that causes human abdominal angiostrongyliasis, a disease found mainly in Latin American countries and particularly in Brazil and Costa Rica. Its life cycle involves exploitation of both invertebrate and vertebrate hosts. Its natural reservoir is a vertebrate host, the cotton rat Sigmodon hispidus. The adult worms live in the ileo-colic branches of the upper mesenteric artery of S. hispidus, causing periarteritis. However, there is a lack of data on the development of vasculitis in the course of infection. OBJECTIVE To describe the histopathology of vascular lesions in S. hispidus following infection with A. costaricensis. METHODS Twenty-one S. hispidus were euthanised at 30, 50, 90 and 114 days post-infection (dpi), and guts and mesentery (including the cecal artery) were collected. Tissues were fixed in Carson’s Millonig formalin, histologically processed for paraffin embedding, sectioned with a rotary microtome, and stained with hematoxylin-eosin, resorcin-fuchsin, Perls, Sirius Red (pH = 10.2), Congo Red, and Azan trichrome for brightfield microscopy analysis. FINDINGS At 30 and 50 dpi, live eggs and larvae were present inside the vasa vasorum of the cecal artery, leading to eosinophil infiltrates throughout the vessel adventitia and promoting centripetal vasculitis with disruption of the elastic layers. Disease severity increased at 90 and 114 dpi, when many worms had died and the intensity of the vascular lesions was greatest, with intimal alterations, thrombus formation, iron accumulation, and atherosclerosis. CONCLUSION In addition to abdominal angiostrongyliasis, our data suggest that this model could be very useful for autoimune vasculitis and atherosclerosis studies.

Estudo da evolução das lesões vasculares presentes na angiostrongilíase abdominal experimental em Sigmodon hispidus (Rodentia: Cricetidae) / Study of the vascular lesions evolution which present in experimentalabdominal angiostrongyliasis in Sigmodon hispidus (Rodentia: Cricetidae)

Introdução: O Angiostrongylus costaricensis é um nematódeo que causa aangiostrongilíase abdominal. O ciclo de vida deste parasita envolve um hospedeiro invertebrado (intermediário) e um hospedeiro vertebrado mamífero (definitivo). Na natureza, um dos principais hospedeiros definitivos deste parasita é o roedor Sigmodon hispidus. O nematódeo instala-se na artéria mesentérica superior do hospedeiro definitivo, causando inicialmente uma periarterite e o sinofílica e posteriormente um trombo. Histopatologicamente, uma tríade de achados fundamentais define esta patologia: massivo infiltrado e o sinofílico; vasculiteeosinofílica e reação granulomatosa. Apesar da importância clínica, pouco se sabe a cerca dessa patologia. Objetivos: Caracterizar as lesões histopatológicas do território vascular e intestinal; acompanhar a dinâmica hematológica periférica e central; avaliar colesterolemia total e a presença de bactérias na lesão de S. hispidusinfectados com A. costaricensis. Material e Métodos: S. hispidus infectados com A. costaricensis foram eutanasiados em 30, 50, 90 e 114 dpi e foram coletados o intestino e mesentério (incluindo a artéria cecal). Os tecidos foram fixados emformalina Millonig de Carson e, histologicamente processados para microscopia de luz ou imunohistoquímica. O sangue também foi coletado através de punção cardíaca ou do plexo braquial e utilizado para realização de hemograma e análise da colesterolemia total e análise microbiológica. A lesão local também foi coletada para análise microbiológica. Resultados e discussão:...

Introduction: Angiostrongylus costaricensis is a roundworm which causes theabdominal angiostrongyliasis. This parasite’s life cycle involves an invertebrate host(intermediary) and a vertebrate host (definitive). In nature, the usual definitive host forthis parasite is the rodent Sigmodon hispidus. Adult worms install in the uppermesenteric artery of the definitive host, causing in the beginning an eosinophilicpolyarteritis and then a thrombus. Histopathologically, a triad of essential findingdefines this pathology as: massive eosinophilic infiltrate; eosinophilic vasculitis andthe granulomatous reaction. Despite the clinical importance, we know just a fewabout this pathology. Objectives: To characterize the histopathological lesions of thevascular and intestinal territories; to follow the peripheral and central hematologicdynamics; to evaluate the total cholesterol and the bacteria presence in the lesion onthe infected S. hispidus by A. costaricensis. Material and Methods: S. hispidusinfected by A. costaricensis were euthanized in 30, 50, 90 and 114 dpi and werecolected the intestine and mesentery (including the cecal artery). Tissues were fixedin Carson’s Millonig formalin and, histopathologically processed to light microscopy orimmunohistochemistry. The blood was also gathered through the cardiac puncture orfrom the brachial plexus and used to the CBC conduction and analysis of totalcholesterol and microbiological analysis. The local lesion was also gathered tomicrobiological analysis. Results and discussion:...