Browsing by Author "Guerra, Luanda Liboreiro"

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    Analysis of the cytokine profile in spleen cells from dogs naturally infected by Leishmania chagasi.
    (2007) Lage, Ramon Silva; Oliveira, Guilherme Corrêa de; Busek, Solange Cristina Uber; Guerra, Luanda Liboreiro; Giunchetti, Rodolfo Cordeiro; Oliveira, Rodrigo Corrêa de; Reis, Alexandre Barbosa
    Recent studies suggest that asymptomatic dogs infected with canine visceral leishmaniasis (CVL) develop a Th1 immunological profile whilst oligosymptomatic and symptomatic CVL-infected animals present a Th2 profile. In the present study, an RT-PCR method has been standardised and employed to evaluate the frequency and the semi-quantitative level of expression of the cytokines IL-4, IL-10, IL-12, INF- g and TNF- a in splenocytes of 30 dogs naturally infected with Leishmania chagasiand of 7 non-infected dogs (NID). An increase in the level of expression of IL-12 ( p = 0.059) was detected in all CVL-infected dogs compared with NID. In dogs exhibiting high parasitism, the frequency of expression of IL-10 was higher ( p = 0.011) than in animals presenting low parasitism or medium parasitism (MP) and in NID animals, whilst the level of expression of IL-10 was higher (p = 0.0094) than in animals exhibiting MP and in the NID group. Positive correlations between the levels of expression of IL-10 with respect to the progression of the disease (IL-10: r = 0.3510; p = 0.0337) and the levels of expression of IL-10 and INF- g increase in parasitism (IL-10: r = 0.3428; p = 0.0438 and INF- g: r = 0.4690; p = 0.0045) were observed. Such data suggest that CVL is marked by a balanced production of Th1 and Th2 cytokines, with a predominant accumulation of IL-10 as a consequence of an increase in parasitic load and progression of the disease, and INF- g was related with the increase in parasitic load.
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    Evaluation of the influence of tissue parasite density on hematological and phenotypic cellular parameters of circulating leukocytes and splenocytes during ongoing canine visceral leishmaniasis.
    (2009) Guerra, Luanda Liboreiro; Carvalho, Andréa Teixeira de; Giunchetti, Rodolfo Cordeiro; Martins Filho, Olindo Assis; Reis, Alexandre Barbosa; Oliveira, Rodrigo Corrêa de
    During Leishmania infection, tissue parasitism at different sites may differ and imply distinct immunopathological patterns during canine visceral leishmaniasis (CVL). For this reason, we have assessed by flow cytometry the impact of spleen and skin parasite density on the phenotypic profile of splenocytes and circulating leukocytes of 40 Brazilian dogs naturally infected by Leishmania chagasi categorized according to splenic and cutaneous parasite load. Our major statistically significant findings demonstrated that dogs with splenic high parasitism presented a significant decrease in absolute counts of CD5+ T lymphocytes in comparison with dogs presenting splenic medium parasitism. Moreover, a decrease in the absolute number of circulating monocytes was observed as a hallmark of high parasitism. The increased frequency of CD8+ T cells is associated with low splenic parasitism during CVL. Although we did not found any significant differences between the immunophenotypic analysis performed in circulating lymphocytes according to cutaneous parasite load, there were negative correlations between CD5+ and CD8+ T cells and cutaneous parasite density reemphasizes the role of T cell-mediated immune response in resistance mechanisms during ongoing CVL. These results add new insights about the pathogenesis of CVL and may help in the establishment of additional tools for future studies on drugs and vaccine approaches.
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    Isotype patterns of immunoglobulins : hallmarks for clinical status and tissue parasite density in brazilian dogs naturally infected by Leishmania (Leishmania) chagasi.
    (2006) Reis, Alexandre Barbosa; Carvalho, Andréa Teixeira de; Vale, André Macedo; Marques, Marcos José; Giunchetti, Rodolfo Cordeiro; Mayrink, Wilson; Guerra, Luanda Liboreiro; Andrade, Renata Aline de; Oliveira, Rodrigo Corrêa de; Martins Filho, Olindo Assis
    The role of anti-leishmanial immune response underlying the susceptibility/resistance during canine visceral leishmaniasis (CVL) has been recognized throughout ex vivo and in vitro investigations. Recently, we demonstrated that immunoglobulin levels (Igs), as well as the parasite load are relevant hallmarks of distinct clinical status of CVL. To further characterize and upgrade the background on this issue, herein, we have evaluated, inLeishmania ( Leishmania ) chagasinaturally infected dogs, the relationship between tissue parasitism (skin, bone marrow, spleen, liver and lymph node), the CVL clinical status (asymptomatic (AD), with no suggestive signs of the disease; oligosymptomatic (OD), with maximum three clinical signs—opaque bristles; localized alopecia and moderate loss of weight; symptomatic (SD), serologically positive with severe clinical signs of visceral leishmaniasis), and the humoral immunological profile of anti-Leishmania immunoglobulins (IgG, IgG1, IgG2, IgM, IgA and IgE). Our major statistically significant findings revealed distinct patterns of tissue parasite density within L. chagasi-infected dogs despite their clinical status, pointing out the spleen and skin as the most relevant sites of high parasitism during ongoing CVL. Parasite density of bone marrow and spleen were the most reliable parasitological markers to decode the clinical status of CVL. Moreover, the parasite density of bone marrow better correlates with most anti- Leishmania Igs reactivity. Additionally, a prognostic hallmark for canine visceral leishmaniasis was found, highlighting strong correlation between IgG1 and asymptomatic disease, but with IgA, IgE and IgG2 displaying better association with symptomatic disease. The new aspects of this study highlighted pioneer findings that correlated the degree of tissue parasite density (low (LP), medium (MP) and high (HP) parasitism) with distinct patterns of anti- Leishmania Igs reactivity. In this scope, our data re-enforce the anti- Leishmania IgG but with IgA reactivity as the better marker for overall tissue parasitism. The association between clinical status, Ig profile and the tissue parasitism support a novel investigation on the impact of humoral immune response and susceptibility/resistance mechanism during ongoing CVL
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    Phenotypic features of circulating leucocytes as immunological markers for clinical status and bone marrow parasite density in dogs naturally infected by Leishmania chagasi.
    (2006) Reis, Alexandre Barbosa; Carvalho, Andréa Teixeira de; Giunchetti, Rodolfo Cordeiro; Guerra, Luanda Liboreiro; Carvalho, Maria das Graças; Mayrink, Wilson; Genaro, Odair; Oliveira, Rodrigo Corrêa de; Martins Filho, Olindo Assis
    Canine visceral leishmaniasis (CVL) manifests itself as a broad clinical spectrum ranging from asymptomatic infection to patent severe disease. Despite relevant findings suggesting changes on lymphocytes subsets regarding the CVL clinical forms, it still remains to be elucidated whether a distinct phenotypic profile would be correlated with degree of tissue parasite density.Herein, we have assessed the correlation between the clinical status as well as the impact of bone marrow parasite density on the phenotypic profile of peripheral blood leucocytes in 40 Brazilian dogs naturally infected by Leishmania chagasi. Our major findings describe the lower frequency of B cells and monocytes as the most important markers of severe CVL. Our main statistically significant findings reveal that the CD8+ T cell subset reflects most accurately both the clinical status and the overall bone marrow parasite density, as increased levels of CD8+ lymphocytes appeared as the major phenotypic feature of asymptomatic disease and dogs bearing a low parasite load. Moreover, enhanced major histocompatibility complex (MHC)-II density as well as a higher CD45RB/CD45RA expression index seems to represent a key element to control disease morbidity. The association between clinical status, bone marrow parasitism and CD8+ T cells re-emphasizes the role of the T cellmediated immune response in the resistance mechanisms during ongoing CVL. Higher levels of circulating T lymphocytes (both CD4+ and CD8+ T cells) and lower MHC-II expression by peripheral blood lymphocytes seem to be the key for the effective immunological response, a hallmark of asymptomatic CVL.