The human immune response during cutaneous leishmaniasis: NO problem.
ABSTRACT During some helminth infections, increased expression of the low-affinity receptor for IgE (CD23/FcepsilonRII) by macrophages and/or increased levels of plasma IgE have been seen, but their role in host protection or disease progression remains unclear. Recently, crosslinking of CD23 was shown to promote intracellular killing of Leishmania parasites in human macrophages, a phenomenon involving the production of tumor necrosis factor alpha and nitric oxide (NO). Based upon various in vitro and in vivo studies of human cutaneous leishmaniasis, Djavad Mossalayi, Michel Arock, Dominique Mazier, Philipe Vincendeau and Ioannis Vouldoukis here propose a model for an immune response that involves CD23-IgE-mediated NO release during protection, as well as during active cutaneous leishmaniasis.
Article: Nitric oxide-mediated proteasome-dependent oligonucleosomal DNA fragmentation in Leishmania amazonensis amastigotes.[show abstract] [hide abstract]
ABSTRACT: Resistance to leishmanial infections depends on intracellular parasite killing by activated host macrophages through the L-arginine-nitric oxide (NO) metabolic pathway. Here we investigate the cell death process induced by NO for the intracellular protozoan Leishmania amazonensis. Exposure of amastigotes to moderate concentrations of NO-donating compounds (acidified sodium nitrite NaNO(2) or nitrosylated albumin) or to endogenous NO produced by lipopolysaccharide or gamma interferon treatment of infected macrophages resulted in a dramatic time-dependent cell death. The combined use of several standard DNA status analysis techniques (including electrophoresis ladder banding patterns, YOPRO-1 staining in flow cytofluorometry, and in situ recognition of DNA strand breaks by TUNEL [terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling] assay) revealed a rapid and extensive fragmentation of nuclear DNA in both axenic and intracellular NO-treated amastigotes of L. amazonensis. Despite some similarities to apoptosis, the nuclease activation responsible for characteristic DNA degradation was not under the control of caspase activity as indicated by the lack of involvement of cell-permeable inhibitors of caspases and cysteine proteases. In contrast, exposure of NO-treated amastigotes with specific proteasome inhibitors, such as lactacystin or calpain inhibitor I, markedly reduced the induction of the NO-mediated apoptosis-like process. These data strongly suggest that NO-induced oligonucleosomal DNA fragmentation in Leishmania amastigotes is, at least in part, regulated by noncaspase proteases of the proteasome. The determination of biochemical pathways leading up to cell death might ultimately allow the identification of new therapeutic targets.Infection and Immunity 08/2002; 70(7):3727-35. · 4.16 Impact Factor
Article: Bacterial lipoprotein-based vaccines induce tumor necrosis factor-dependent type 1 protective immunity against Leishmania major.[show abstract] [hide abstract]
ABSTRACT: Immunity against Leishmania major requires rapid induction of a type 1 immune response in which tumor necrosis factor alpha (TNF-alpha) plays an essential role. Hence, vaccination strategies that simulate the protective immune response found in hosts that have recovered from natural infection provide a rational approach to combat leishmaniasis. One method for optimizing the qualitative and quantitative immune responses after vaccination is to use an adjuvant. In this study we demonstrate that the OprI lipoprotein (L-OprI) from Pseudomonas aeruginosa induces a long-term cellular (gamma interferon [IFN-gamma]) and humoral (immunoglobulin G2a) type 1 immune response against a truncated 32-kDa version (COOHgp63) of the 63-kDa major cell surface glycoprotein gp63. By contrast, immunization with COOHgp63 either fused to OprI nonlipoprotein or with no adjuvant did not result in the induction of type 1 immune responses. The adjuvanticity of L-OprI is strongly dependent on its capacity to induce TNF-alpha, since generation of type 1 immune responses is clearly delayed and impaired in TNF-alpha(-/-) mice. Vaccination with L-OprICOOHgp63 fusion protein protected BALB/c mice against L. major infection for at least 19 weeks. Vaccinated mice were largely free of lesions or clearly controlled lesion size on termination of the experiment. The control of disease progression in mice vaccinated with L-OprICOOHgp63 was associated with enhancement of antigen-specific IFN-gamma production. These data indicate that bacterial lipoproteins constitute appropriate adjuvants to include in vaccines against diseases in which type 1 immune responses are important for protection.Infection and Immunity 02/2002; 70(1):240-8. · 4.16 Impact Factor