Troponina C na detecção imuno-histoquímica de alterações regressivas precoces no miocárdio de ovinos naturalmente intoxicados por Amaranthus spinosus (Amaranthaceae)

Abstract

ABSTRACT.-Costa S.Z.R., Peixoto P.V., Brust L.A.C., d' Avila M.S., Santos A.M., Driemeier D., Nogueira V. A. & França T.N. 2016. [Troponin C in the immunohistochemistry detection of early regressive changes in sheep myocardium naturally poisoned by Amaranthus spinosus (Amaranthaceae).] Troponina C na detecção imuno-histoquímica de alterações regressivas precoces no miocárdio de ovinos naturalmente intoxicados por Amaranthus spinosus (Amaranthaceae). Pesquisa Veterinária Brasileira 36(2):83-89. Curso de Pós-Graduação em Medicina Veterinária, Instituto de Veterinária, Universidade Federal Rural do Rio de Janeiro, BR-465 Km 7, Seropédica, RJ 23890-000, Brazil. E-mail: samayzillmann@gmail.com Amaranthus spp. are nephrotoxic plants popularly known as "pigweed". In cases of poisoning by these plants, the main histopathological alteration is found in the kidneys as toxic tubular nephrosis; however, in some cases, there may be cardiac changes. ECG changes associated with hyperkalemia have been described in pigs poisoned by Amaranthus retroflexus. Degeneration and necrosis of myocytes have been described in pigs poisoned by A. caudatus and sheep poisoned by A. spinosus. There are doubts regarding cardiac changes, since in most cases they are incipient and don't exhibit inflammatory reaction, which can lead to misinterpretation. For this study, paraffin blocks with tissues from a poisoning outbreak by A. spinosus in southeastern Brazil were used. The objective of the study was to detect the presence of incipient regressive changes in the myocardium of sheep poisoned by A. spinosus using anti-troponin C antibody-based immunohistochemistry. Fragments of hearts from 8 adult sheep and 2 fetuses naturally poisoned by A. spinosus were used. In the immunohistochemistry evaluation of the 8 hearts from the adult sheep there were several groups of myocytes with significant decrease or absence of immunoreactivity for anti-troponin C antibody. In most cases, these same areas on Hematoxylin and Eosin (HE) staining exhibited changes that varied from mild cellular tumefaction to increased eosinophilia, as well as loss of striation, cell lysis and karyolysis, sometimes accompanied by inflammatory infiltrate. In four cases, it was possible to notice that several small groups of myocytes exhibited decreased immunoreactivity corresponding to cells with undetectable or very subtle alterations on HE staining. The hearts of both fetuses did not exhibit areas with loss or decreased immunoreactivity for the anti-troponin C antibody. The results of this immunohistochemical evaluation confirmed the presence of incipient regressive changes and confirmed the occurrence of well-established necrotic lesions in the myocardium of sheep poisoned by Amaranthus spinosus. There was correspondence between areas where immunostaining for troponin was absent and areas with the most marked lesions obser-1 Recebido em 24 de julho de 2015Aceito para publicação em 28 de novembro de 2015 Parte da Tese de Doutorado do primeiro autor.

Clinical-pathological and immunohistochemical evaluations of cardiac lesions in cats with chronic kidney disease

“…There was an increase in eosinophilic cardiomyocytes confirmed by the loss of troponin from cardiac myocytes through IHC using human cTnC antibody. These findings corroborate those observed in dogs with CKD and heartworm disease (Carretón et al 2012(Carretón et al , D'avila et al 2016, sheep with acute and subacute nephrotoxic injury (Costa et al 2016), and cattle (Pavarini et al 2012, Bandinelli et al 2014 with cardiac injuries, which confirm the viability of this technique for these species. Regarding the extent of cardiac injury in cats, small foci of isolated necrosis or individual cardiomyocytes were observed, demonstrating that, even in advanced stages of CKD, cardiac lesions manifest differently in this species, which can be explained by the different pathophysiology and consequent clinical-pathological behavior of the feline species (Bagshaw et al 2013).…”

“…Few studies have reported the use of IHC with anti-troponin antibody to detect cardiac lesions in veterinary medicine. Recently, through IHC for the human cTnC antibody, degenerative-necrotic lesions have been observed in the heart of cattle poisoned by Amorimia exotropica (Pavarini et al 2012, Bandinelli et al 2014) and of sheep poisoned by Amaranthus spinosus (Costa et al 2016). Foci of hypereosinophilic cardiomyocytes with coagulation necrosis, neutrophilic inflammation, and subtle to mild variation in the staining pattern of some fibers with part of them showing a total loss of troponin I were found in the myocardium of dogs infected with Dirofilaria immitis (Carretón et al 2012(Carretón et al ).…”

“…Several immunohistochemical techniques with high specificity and sensitivity have been developed aiming to detect damage to the cardiomyocytes. Among these, cardiac troponin has shown promising results in cattle (Ortmann et al 2000, Pavarini et al 2012, Bandinelli et al 2014, sheep (Costa et al 2016), anddogs (D'avila et al 2016). Necrotic cardiomyocytes, detectable or not by routine optical microscopy exams, show negative immunostaining, while those unaffected are positive for troponin (Jenkins et al 2010, Bandinelli et al 2014Costa et al 2016.…”

Troponina C na detecção imuno-histoquímica de alterações regressivas precoces no miocárdio de bovinos e ovinos intoxicados por monofluoroacetato de sódio

“…A diminuição ou ausência da expressão de troponina cardíaca observada em todos os bovinos e ovinos desse estudo, indica variável grau de lesão de cardiomiócitos. Recentemente, lesões degenerativo-necróti-cas semelhantes foram demonstradas através da imuno--histoquímica para cTnC no coração de bovinos intoxicados por Amorimia exotropica (Pavarini et al 2012, Bandinelli et al 2014) e ovinos por Amaranthus spinosus (Costa et al 2014). Além disso, estudos anteriores relatam o aumento da eosinofilia citoplasmática de fibras cardíacas em bovinos intoxicados por Mascagnia (Amorimia) sp.…”

“…Em ovinos, a troponina sérica foi dosada em casos de arritmia cardíaca após intoxicação por salinomicina (Hajimohammadi et al 2014) e lesão miocárdica em animais com acidose lática ruminal (Kirbas et al 2014). Com relação à imuno-histoquímica, são escassos os trabalhos que relatam o uso do anticorpo anti-cTnC na detecção de alterações cardíacas em bovinos (Tunca et al 2008, Pavarini et al 2012) e ovinos (Costa et al 2014). O anticorpo anticTnC humano é sensível para detectar lesões cardíacas em bovinos (Pavarini et al 2012) e ovinos (Costa et al 2014), o que sugere que os sítios antigênicos para estas proteínas são similares entre as espécies testadas.…”