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

Abstract

This study was about a semi-quantitative analysis of T lymphocytes (CD4 + and CD8 + , FoxP3 + regulatory T cells), and macrophages in the gut wall of dogs naturally infected with Leishmania infantum. Thirteen dogs were divided into three groups: group 1 (G1, n=5), dogs with canine visceral leishmaniasis (CVL) and infected with L. infantum amastigotes in the intestine; group 2 (G2, n=5), dogs with CVL but without intestinal amastigotes; and group 3 (G3, n=3), uninfected dogs (control group). There was no significant difference (p ≥ 0.05) on CD4 + and Treg cell numbers among the groups, whereas the levels of CD8 + T cells and macrophages were significantly higher in dogs from G1 group than in G2 and G3 (p ≤ 0.05), especially in intestinal segments with high parasite burden. Parasite burden correlated positively with levels of CD8 + T cells and macrophages (p ≤ 0.05), but was inversely correlated to levels of CD4 + T lymphocytes and FoxP3 + Treg cells. In conclusion, in the intestine of dogs with CVL, the increase of CD8 + T cells and macrophages population associated with high parasite burdens, but no changes of CD4 + T cells and FoxP3 + Treg cells suggest a possible immunoregulation by the parasite not dependent on Treg cells.Keywords: T lymphocytes, macrophages, canine visceral leishmaniasis, intestinal tract. ResumoEste estudo foi uma análise semi-quantitativa de linfócitos T (CD4 + , CD8 + e regulatórios -Treg FoxP3 + ) e macrófagos na parede intestinal de cães naturalmente infectados com Leishmania infantum. Treze cães foram divididos em três grupos: grupo 1 (G1, n=5) continha cães com leishmaniose visceral canina (LVC) e com amastigotas intestinais; grupo 2 (G2, n=5) continha cães com LVC, mas sem amastigotas intestinais e o grupo 3 (G3, n=3) continha cães não infectados (grupo controle). Verificou-se que não houve diferença significativa (p ≤ 0.05) no número de células CD4 + e de Treg entre os grupos, mas o número de células T CD8 + e macrófagos foi significativamente superior nos cães do grupo G1 em relação ao G2 e ao G3 (p ≤ 0,05), especialmente nos segmentos intestinais com altas cargas parasitárias. As altas cargas parasitarias correlacionaram positivamente com os números de CD8 + e macrófagos (p ≤ 0,05), mas negativamente com as células CD4 + e Treg. Em conclusão, no intestino dos cães com LVC, o aumento das populações de células T CD8 + e de macrófagos associado a altas cargas parasitárias, mas nenhuma alteração de células T CD4 + e células Treg FoxP3 + sugerem uma possível imunorregulação pelo parasita não dependente de células Treg.Palavras-chave: Linfócito T, macrófagos, leishmaniose visceral canina, trato intestinal.

Investigating associations between intestinal alterations and parasite load according to Bifidobacterium spp. and Lactobacillus spp. abundance in the gut microbiota of hamsters infected by Leishmania infantum

“…All studies reporting on tissue changes in IT arising from Leishmania sp infection detected changes in the ratio of lymphocytes to epithelial cells. (16,23,24) In the megaesophagus and megacolon, neuronal degeneration has been associated with enteric ganglion invasion by cytotoxic T cells. (37) Herein, the alterations seen in the myenteric and submucosal plexuses occurred simultaneously with histopathological changes, i.e.…”

“…have shown histopathological alterations in the jejunum and colon, as well as changes in the expression of immune receptors, cytokines and immune cells. (13,14,15,16) Among all VL experimental models, the Golden Syrian hamster Mesocricetus auratus is considered a superior animal model to evaluate the parasite-host relationship, immunopathogenesis, drug discovery and vaccine development studies; (17,18,19,20,21) however these animals have not been used to investigate the effects of VL on IT and GM.…”

The Effect of FOXP3+ Regulatory T Cells on Infectious and Inflammatory Diseases

“…For instance, investigation of T cell immunity in dog models indicated that in the intestine, the percentage of CD8 + T cells and macrophage increased while numbers of CD4 + T cells and FOXP3 + Tregs were not influenced in the Leishmania-infected group. 32 In infected dogs, the number of T cells decreased while the IL-10 + Tregs increased in the spleen. 33 These data suggest that Tregs play important roles during Leishmania infections.…”

“…Several studies showed that hepatic stellate cells are critical to the incidence of leishmaniasis. For instance, investigation of T cell immunity in dog models indicated that in the intestine, the percentage of CD8 + T cells and macrophage increased while numbers of CD4 + T cells and FOXP3 + Tregs were not influenced in the Leishmania -infected group 32 . In infected dogs, the number of T cells decreased while the IL-10 + Tregs increased in the spleen 33 .…”