Hypoxia modulates expression of the 70-kD heat shock protein and reduces Leishmania infection in macrophages.

Department of Parasitology, Biology Institute, Universidade Estadual de Campinas, Campinas, SP, Brazil.
Journal of Biomedical Science (Impact Factor: 2.74). 10/2004; 11(6):847-54. DOI: 10.1159/000081832
Source: PubMed

ABSTRACT Hypoxia, a microenvironmental factor present in diseased tissues, has been recognized as a specific metabolic stimulus or a signal of cellular response. Experimental hypoxia has been reported to induce adaptation in macrophages such as differential migration, elevation of proinflammatory cytokines and glycolytic enzyme activities, and decreased phagocytosis of inert particles. In this study we demonstrate that although exposure to hypoxia (5% O2, 5% CO2, and balanced N2) did not change macrophage viability, or 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cleavage and proliferation, it significantly reduced expression of the 70-kD heat shock protein (HSP70), which was restored to prehypoxia levels after reoxygenation. The influence of low oxygen tension on macrophage functional activity was also studied, i.e. the ability of these cells to maintain or resist infection by a microorganism. We demonstrate that macrophages from two different sources (a murine cell line and primary cells) exposed to hypoxia were efficiently infected with Leishmania amazonensis, but after 24 h showed a reduction in the percentage of infected cells and of the number of intracellular parasites per macrophage, indicating that hypoxia induced macrophages to kill the intracellular parasites. These results support the notion that hypoxia, a microenvironmental factor, can modulate macrophage protein expression and functional activity.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Macrophages are among the oldest cell types in the animal kingdom, and they have a long evolutionary history and experience various evolutionary pressures. It was clear from the earliest studies that variations exist in macrophage populations. Macrophages are known to adapt to their microenvironment. Although the paradigm for macrophage plasticity is their flexible program driven by environmental signals, the most common working hypothesis is that of a dichotomy between two major macrophage phenotypes, M1 and M2. A PubMed and Web of Science databases search was performed providing evidences that numerous authors have expanded the concept of plasticity and conducted experimental studies focusing on the complex program of phenotypes. This review evaluated a number of issues relating to macrophage plasticity, environmental heterogeneity and the potential for changes to be reversal or non reversal in an ecological context. The ecological principles of phenotypic plasticity which can assist in evaluating and interpreting macrophage experimental data are discussed as well.
    Agents and Actions 07/2013; 62(9). DOI:10.1007/s00011-013-0647-7 · 2.14 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: T-complex protein-1 (TCP1) complex, a chaperonin class of protein, ubiquitous in all genera of life, is involved in intracellular assembly and folding of various proteins. The gamma subunit of TCP1 complex (TCP1γ), plays a pivotal role in the folding and assembly of cytoskeleton protein(s) as an individual or complexed with other subunits. Here, we report for the first time cloning, characterization and expression of the TCP1γ of Leishmania donovani (LdTCP1γ), the causative agent of Indian Kala-azar. Primary sequence analysis of LdTCP1γ revealed the presence of all the characteristic features of TCP1γ. However, leishmanial TCP1γ represents a distinct kinetoplastid group, clustered in a separate branch of the phylogenic tree. LdTCP1γ exhibited differential expression in different stages of promastigotes. The non-dividing stationary phase promastigotes exhibited 2.5 fold less expression of LdTCP1γ as compared to rapidly dividing log phase parasites. The sub-cellular distribution of LdTCP1γ was studied in log phase promastigotes by employing indirect immunofluorescence microscopy. The protein was present not only in cytoplasm but it was also localized in nucleus, peri-nuclear region, flagella, flagellar pocket and apical region. Co-localization of LdTCP1γ with actin suggests that, this gene may have a role in maintaining the structural dynamics of cytoskeleton of parasite.
    Biochemical and Biophysical Research Communications 11/2012; 429(1-2). DOI:10.1016/j.bbrc.2012.10.090 · 2.28 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Autophagy is the primary mechanism of degradation of cellular proteins and at least two functions can be attributed to this biological phenomenon: increased nutrient supply via recycling of the products of autophagy under nutrient starvation; and antimicrobial response involved in the innate immune system. Many microorganisms induce host cell autophagy and it has been proposed as a pathway by which parasites compete with the host cell for limited resources. In this report we provide evidence that the intracellular parasite Leishmania amazonensis induces autophagy in macrophages. Using western blotting, the LC3II protein, a marker of autophagosomes, was detected in cell cultures with a high infection index. Macrophages infected with L. amazonensis were examined by transmission electronic microscopy, which revealed enlarged myelin-like structures typical late autophagosome and autolysosome. Other evidence indicating autophagy was Lysotracker red dye uptake by the macrophages. Autophagy also occurs in the leishmaniasis skin lesions of BALB/c mice, detected by immunohistochemistry with anti-LC3II antibody. In this study, autophagy inhibitor 3-methyladenine (3MA) reduced the infection index, while autophagy inductors, such as rapamycin or starvation, did not alter the infection index in cultivated macrophages, suggesting that one aspect of the role of autophagy could be the provision of nutritive support to the parasite.
    Tissue and Cell 08/2012; 44(6). DOI:10.1016/j.tice.2012.08.003 · 1.05 Impact Factor