Correlation study and histopathological description of intestinal alterations in dogs infected with Leishmania infantum

Abstract

The aim of this work was a correlation study and histopathological description of alterations associated with the presence of Leishmania infantum amastigote in the intestinal wall of dogs infected with canine visceral leishmaniasis (CVL). Three groups were used: G1 (n = 8), comprising naturally infected dogs with CVL with amastigotes of L. infantum in the small and large intestines; G2 (n = 9), infected dogs with CVL, without intestinal amastigotes; and G3 (n = 3), uninfected dogs. Histochemistry and immunohistochemistry methods were used for histopathology and amastigotes identification. 47.1% (8/17) of dogs from G1 group had amastigotes in the mucosa, submucosa and muscle layers of the small and large intestines and it was observed a prominent inflammatory reaction characterized by chronic infiltration of mononuclear cells: macrophages, lymphocytes and plasma cells. Comparison between the groups showed only a significant difference in relation to mucosal microscopic structural alterations in dogs from G1 in relation to G2 and G3. Parasite burden showed significant correlations with the microscopic alterations and clinical status of dogs in G1. By the conclusion, the inflammatory reactions caused by the parasites in the intestines might have contributed towards alterations in digestive processes, worsening the dogs' clinical status of CVL.Keywords: Dog, histology, immunohistochemistry, intestine, leishmaniasis, amastigotes. ResumoO objetivo foi realizar um estudo de correlação e descrição histopatológica das lesões associadas à presença de amastigotas de Leishmania infantum na parede intestinal de cães infectados com leishmaniose visceral canina (LVC). Os cães foram subdivididos em três grupos: G1 (n = 8) cães naturalmente infectados com LVC e com amastigotas de L. infantum no intestino; G2 (n = 9) com LVC, mas sem o parasitismo intestinal; e G3 (n = 3) cães não infectados. Métodos histoquímicos e imunoistoquímicos foram utilizados para a histopatologia e a identificação das amastigotas, respectivamente. 47,1% (8/17) dos cães infectados (grupo G1) apresentavam formas amastigotas na mucosa, submucosa e camada muscular do intestino delgado e grosso, destacando-se uma reação inflamatória caracterizada por infiltrado crônico de células mononucleares; macrófagos, linfócitos e plasmócitos. Observou-se uma diferença significativa somente com relação às alterações estruturais microscópicas intestinais nos cães do G1 quando comparadas com G2 e G3. A intensidade parasitária intestinal teve correlação significativa com as alterações microscópicas e os sinais clínicos dos cães do G1. Concluiu-se que as amastigotas de L. infantum por causarem reações inflamatórias na parede intestinal dos cães podem ter contribuído para as alterações dos processos digestórios, agravando ainda mais o quadro clínico dos animais.Palavras-chave: Cão, histologia, imunoistoquímica, intestino, leishmaniose, amastigotas.

T lymphocytes and macrophages in the intestinal tissues of dogs infected with Leishmania infantum

“…Program R, version 3.1.1 (R CORE TEAM, 2017). and colon of a dog with CVL associated with a chronic intestinal inflammatory reaction (PINTO et al, 2011(PINTO et al, , 2013SILVA et al, 2016). Additional information about histopathological description of intestinal alterations of the dogs (G1 group) of this study can be found in Silva et al (2016).…”

“…Leishmania infantum is an intracellular parasite that multiplies in macrophages residing in several organs and lymphoid tissues, including intestinal tissues of dogs (PINTO et al, 2011(PINTO et al, , 2013SILVA et al, 2016), causing clinical and pathological alterations (FEITOSA et al, 2000). Anderson et al (1980) observed macrophage infected with L. infantum in the lamina propria and submucosa of the stomach, duodenum, jejunum, ileum, Note: According to the F-test, there is no significant difference to the level of 5% probability (p ≤ 0.05).…”

“…and colon of a dog with CVL associated with a chronic intestinal inflammatory reaction (PINTO et al, 2011(PINTO et al, , 2013SILVA et al, 2016). Additional information about histopathological description of intestinal alterations of the dogs (G1 group) of this study can be found in Silva et al (2016). In the present study, the increase of macrophages in intestinal tissues (small and large intestines) was observed in CVL-positive dogs (G1 and G2 groups), but hypertrophic macrophages with L. infantum amastigotes were seen only in G1 dogs (naturally infected dogs with intestinal amastigotes).…”

“…An inflammatory reaction in the gastrointestinal (GI) tract associated with the presence of intramacrophagic Leishmania amastigotes has been reported in experimentally infected dogs (KEENAN et al, 1984) and in naturally infected dogs (FERRER et al, 1991;PINTO et al, 2011;TOPLU & AYDOGAN, 2011;SILVA et al, 2016). Although uncommon, occurrences of erosive and ulcerative colitis and hemorrhagic diarrhea have been described in dogs in association with severe clinical signs of disease (GONZÁLEZ et al, 1990;FERRER et al, 1991).…”

Infection by Leishmania (Leishmania) infantum chagasi causes intestinal changes B‐1 cells dependent

“…The intestine is an important immune organ affected in the presence of VL . Intestinal changes have been evidenced, such as inflammatory infiltration, epithelial degeneration and alterations in the muscular layer in dogs, in addition to intracellular amastigotes that were found in humans along with diarrhoea and malabsorption …”