Cellular immunophenotypic profile in the splenic compartment during canine visceral leishmaniasis
Alexandre Barbosa Reis1, Andréa Teixeira-Carvalho2, Rodolfo Cordeiro Giunchetti3
1Programa de Pós-Graduação em Ciências Farmacêuticas, Escola de Farmácia, Universidade Federal de Ouro Preto, Ouro Preto, CEP 35400-000 Minas Gerais, Brasil; Núcleo de Pesquisa em Ciências Biológicas, Universidade Federal de Ouro Preto, Ouro Preto, Minas Gerais CEP 35400-000, Brasil; Instituto Nacional de Ciência e Tecnologia em Doenças Tropicais, Salvador, Bahia, Brasil.
Insights
The spleen
Area of Science:
- Veterinary Immunology
- Parasitology
- Canine Infectious Diseases
Background:
- Canine visceral leishmaniasis (CVL) is a significant zoonotic disease caused by Leishmania infantum.
- The spleen's role in CVL pathogenesis and immune response remains incompletely understood.
- Understanding splenic immune cell dynamics is crucial for diagnosing and managing CVL.
Purpose of the Study:
- To investigate the role of splenic cellular immunophenotypic profiles in the pathogenesis of canine visceral leishmaniasis (CVL).
- To correlate splenic immune cell populations and functions with clinical status in Leishmania infantum-infected dogs.
- To identify potential biomarkers for asymptomatic versus symptomatic CVL.
Main Methods:
- Analysis of splenic cellular immunophenotypic profiles in 52 naturally infected dogs with varying clinical presentations (asymptomatic, oligosymptomatic, symptomatic) and 7 controls.
- Flow cytometry was used to assess T cell subsets (CD4+, CD8+), B cells (CD21+), and activation markers (MHC-II).
- In vitro splenocyte proliferation assays and Leishmania soluble antigen (LSA) stimulation were performed to evaluate immune responses.
Main Results:
- Asymptomatic dogs (AD-II) showed higher CD8+ T splenocytes and a lower CD4+/CD8+ ratio compared to controls.
- Oligosymptomatic and symptomatic dogs exhibited lower CD21+ cell percentages than asymptomatic dogs.
- Splenocyte proliferation index inversely correlated with clinical severity; symptomatic dogs displayed reduced MHC-II expression upon LSA stimulation.
Conclusions:
- CD8+ T splenocytes play a crucial role in effective immune responses, characteristic of asymptomatic CVL.
- Reduced MHC-II expression in splenocytes after LSA stimulation is a potential biomarker for symptomatic CVL.
- Splenic immunophenotyping offers insights into disease progression and host-parasite interactions in CVL.
Abstract:
To determine the role of the spleen in the pathogenesis of canine visceral leishmaniasis (CVL), we analyzed cellular immunophenotypic profiles of 52 dogs naturally infected with Leishmania infantum, clinically classified as follows: asymptomatic dogs-I (AD-I), seronegative/PCR+; asymptomatic dogs-II (AD-II), seropositive/PCR+; oligosymptomatic dogs (OD) and symptomatic dogs (SD). Seven non-infected dogs (CD) were included as a control group. AD-II presented higher levels of CD8+ T splenocytes and lower TCD4+/TCD8+ ratio in comparison with CD. OD and SD showed lower percentages of CD21+ as compared with AD-II. All seropositive dogs presented lower levels of CD45RA+ than CD. Regardless of the stimuli used, the proliferation index from splenocytes in vitro was inversely correlated with clinical status. After LSA stimulation, there was a higher percentage of specific CD8+ T in AD-II than CD and non-stimulated culture. In contrast, splenocytes from SD under in vitro LSA stimulation induced decreased MHC-II+ expression in comparison with all groups, and non-stimulated culture. In conclusion, the role of CD8+ T splenocytes seems to be important for an effective immunological response, a hallmark of asymptomatic CVL, whereas the pronounced loss of MHC-II expression upon LSA stimulation is a biomarker of symptomatic CVL.
