Development of a Natural Model of Cutaneous Leishmaniasis: Powerful Effects of Vector Saliva and Saliva Preexposure on the Long-Term Outcome of Leishmania major Infection in the Mouse Ear Dermis
16 Nov 1998-Journal of Experimental Medicine (The Rockefeller University Press)-Vol. 188, Iss: 10, pp 1941-1953
TL;DR: The studies reveal a dramatic exacerbating effect of SGS on lesion development in the dermal site, and a complete abrogation of this effect in mice preexposed to salivary components, the first to suggest that for individuals at risk of vector-borne infections, history of exposure to vector saliva might influence the outcome of Exposure to transmitted parasites.
Abstract: We have developed a model of cutaneous leishmaniasis due to Leishmania major that seeks to mimic the natural conditions of infection. 1,000 metacyclic promastigotes were coinoculated with a salivary gland sonicate (SGS) obtained from a natural vector, Phlebotomus papatasii, into the ear dermis of naive mice or of mice preexposed to SGS. The studies reveal a dramatic exacerbating effect of SGS on lesion development in the dermal site, and a complete abrogation of this effect in mice preexposed to salivary components. In both BALB/c and C57Bl/6 (B/6) mice, the dermal lesions appeared earlier, were more destructive, and contained greater numbers of parasites after infection in the presence of SGS. Furthermore, coinoculation of SGS converted B/6 mice into a nonhealing phenotype. No effect of SGS was seen in either IL-4- deficient or in SCID mice. Disease exacerbation in both BALB/c and B/6 mice was associated with an early (6 h) increase in the frequency of epidermal cells producing type 2 cytokines. SGS did not elicit type 2 cytokines in the epidermis of mice previously injected with SGS. These mice made antisaliva antibodies that were able to neutralize the ability of SGS to enhance infection and to elicit IL-4 and IL-5 responses in the epidermis. These results are the first to suggest that for individuals at risk of vector-borne infections, history of exposure to vector saliva might influence the outcome of exposure to transmitted parasites.
Citations
More filters
TL;DR: Established models of T-helper-2-cell dominance in BALB/c mice infected with Leishmania major — involving the early production of interleukin-4 by a small subset of LeishMania-specific CD4+ T cells — have been refined by accumulating evidence that this response is not sufficient and, under some circumstances, not required to promote susceptibility.
Abstract: Established models of T-helper-2-cell dominance in BALB/c mice infected with Leishmania major -- involving the early production of interleukin-4 by a small subset of Leishmania-specific CD4+ T cells -- have been refined by accumulating evidence that this response is not sufficient and, under some circumstances, not required to promote susceptibility. In addition, more recent studies in L. major-resistant mice have revealed complexities in the mechanisms responsible for acquired immunity, which necessitate the redesign of vaccines against Leishmania and other pathogens that require sustained cell-mediated immune responses.
1,136 citations
Cites background from "Development of a Natural Model of C..."
...Furthermore, pre-exposure of mice to sandfly saliva was found to neutralize the enhancing effects of saliv...
[...]
TL;DR: A novel therapeutic approach to eliminate latency, infection reservoirs, and the risk of reactivation disease is suggested as sterile cure was achieved in IL-10–deficient and IL-4/IL-10 double-deficient mice.
Abstract: Some pathogens (e.g., Mycobacterium tuberculosis, Toxoplasma gondii, Leishmania spp) have been shown to persist in their host after clinical cure, establishing the risk of disease reactivation. We analyzed the conditions necessary for the long term maintenance of Leishmania major in genetically resistant C57BL/6 mice after spontaneous healing of their dermal lesions. Interleukin (IL)-10 was found to play an essential role in parasite persistence as sterile cure was achieved in IL-10–deficient and IL-4/IL-10 double-deficient mice. The requirement for IL-10 in establishing latency associated with natural infection was confirmed in IL-10–deficient mice challenged by bite of infected sand flies. The host-parasite equilibrium was maintained by CD4+ and CD8+ T cells which were each able to release IL-10 or interferon (IFN)-γ, and were found to accumulate in chronic sites of infection, including the skin and draining lymph node. A high frequency of the dermal CD4+ T cells released both IL-10 and IFN-γ. Wild-type mice treated transiently during the chronic phase with anti–IL-10 receptor antibodies achieved sterile cure, suggesting a novel therapeutic approach to eliminate latency, infection reservoirs, and the risk of reactivation disease.
583 citations
Cites methods from "Development of a Natural Model of C..."
...Parasite titrations in biphasic media for estimation of parasite loads were performed as described previously (16)....
[...]
TL;DR: Results indicate that DTH response against saliva provides most or all of the protective effects of this vaccine and that salivary gland proteins or their cDNAs are viable vaccine targets against leishmaniasis.
Abstract: Leishmania parasites are transmitted to their vertebrate hosts by infected phlebotomine sand fly bites. Sand fly saliva is known to enhance Leishmania infection, while immunity to the saliva protects against infection as determined by coinoculation of parasites with vector salivary gland homogenates (SGHs) or by infected sand fly bites (Kamhawi, S., Y. Belkaid, G. Modi, E. Rowton, and D. Sacks. 2000. Science. 290:1351–1354). We have now characterized nine salivary proteins of Phlebotomus papatasi, the vector of Leishmania major. One of these salivary proteins, extracted from SDS gels and having an apparent mol wt of 15 kD, was able to protect vaccinated mice challenged with parasites plus SGH. A DNA vaccine containing the cDNA for the predominant 15-kD protein (named SP15) provided this same protection. Protection lasted at least 3 mo after immunization. The vaccine produced both intense humoral and delayed-type hypersensitivity (DTH) reactions. B cell–deficient mice immunized with the SP15 plasmid vaccine successfully controlled Leishmania infection when injected with Leishmania plus SGH. These results indicate that DTH response against saliva provides most or all of the protective effects of this vaccine and that salivary gland proteins or their cDNAs are viable vaccine targets against leishmaniasis.
382 citations
Cites background or result from "Development of a Natural Model of C..."
...papatasi SGH induce the release of IL-4 at the site of inoculation (15)....
[...]
...papatasi SGH confer protection to subsequent inoculation of parasites plus SGH (15, 18), we hypothesize that this immunity is not due to neutralization of salivary immunomodulators— such as adenosine—but rather to the modification of the parasite inoculation site due to a cell-mediated reaction with salivary gland antigens....
[...]
...Having proposed that immunity to sand fly saliva may confer protection to subsequent Leishmania infection (15, 18), we proceeded to (a) characterize the main proteins in the salivary glands of the sand fly P....
[...]
...We previously suggested that the exacerbating effect of SGH was mediated by an early release of IL-4 at the inoculation site (15)....
[...]
...For example, in a previous work, the release of IL-4 was neutralized by antibodies against SGH in presensitized mice, a result correlating with protection against infection (15)....
[...]
TL;DR: The results extend to a natural infection model a role for Th1 cells in both acquired resistance and lesion formation, and document the remarkable avoidance of this response during a prolonged phase of parasite amplification in the skin.
Abstract: A model of Leishmania major infection in C57BL/6 mice has been established that combines two main features of natural transmission: low dose (100 metacyclic promastigotes) and inoculation into a dermal site (the ear dermis). The evolution of the dermal lesion could be dissociated into two distinct phases. The initial “silent” phase, lasting 4–5 wk, favored establishment of the peak load of parasites in the dermis in the absence of lesion formation or any overt histopathologic changes in the site. The second phase corresponds to the development of a lesion associated with an acute infiltration of neutrophils, macrophages, and eosinophils into the dermis and was coincident with the killing of parasites in the site. The onset of immunity/pathology was correlated with the appearance of cells staining for IL-12p40 and IFN-γ in the epidermal compartment, and an expansion of T cells capable of producing IFN-γ in the draining lymph node. Parasite growth was not enhanced over the first 4.5 wk in anti-CD4-treated mice, SCID mice, or C57BL/6 mice deficient in IL-12p40, IFN-γ, CD40 ligand, or inducible NO synthase. These mice all failed to ultimately control infection in the site, but in some cases (anti-CD4 treated, IL-12p40−/−, CD40 ligand−/−, and SCID) high dermal parasite loads were associated with little or no pathology. These results extend to a natural infection model a role for Th1 cells in both acquired resistance and lesion formation, and document the remarkable avoidance of this response during a prolonged phase of parasite amplification in the skin.
377 citations
Cites background or methods from "Development of a Natural Model of C..."
...The dermal cells were identified by characteristic size (forward scatter) and granulosity (side scatter) combined with two-color analysis, as previously described ( 11 )....
[...]
...The epidermal cells were recovered as previously described ( 11 ) with modifications; briefly, the ventral and dorsal ear sheets were separated and transferred dermal side down on DMEM-penicillin/streptomycin with 0.5% trypsin (U.S....
[...]
...Cultures were incubated at 37°C in 5% CO 2. Supernatant fluids were harvested at 24 and 48 h and were assayed for IL-4 and IFN-g, respectively, by ELISA as previously described ( 11 )....
[...]
...The ear dermis was chosen as the inoculation site because, in addition to being a common transmission site in rodent reservoirs, it offers the advantage that all the dynamic events occurring at the site of infection as well as the interconnected compartments of the epidermis and draining lymph node can be carefully monitored ( 11 , 12)....
[...]
...We previously established a model of natural infection that focused on the exacerbating effects of vector saliva on lesion development in a dermal site ( 11 )....
[...]
TL;DR: A summary of the new findings in the emerging field of monocyte heterogeneity is given and a short description of the differentiation patterns of blood monocyte subpopulations are provided, with an emphasis on how these sub Populations can be influenced by infection.
Abstract: The term "monocyte" implies a single, homogenous population of cells with uniform physiology. Recent evidence from a number of laboratories indicates that it is likely that blood monocytes may consist of several subpopulations of cells, which differ in size, nuclear morphology, granularity, and functionality. The aim of this review is to give a summary of the new findings in the emerging field of monocyte heterogeneity. We provide a short description of the differentiation patterns of blood monocyte subpopulations, with an emphasis on how these subpopulations can be influenced by infection. We provide a comparison among the main monocyte subpopulations in humans, mice, and rats and illustrate some of the common features of these cells and some of the important interspecies distinctions. We will also discuss the bone marrow precursors of these cells and the differentiation patterns of these subsets in different tissues in response to infection. Most of the data about monocyte trafficking during infection are necessarily derived from murine models, and comparisons between mouse and man must be made with caution. However, these models may provide interesting springboards to permit us to speculate about the topic of monocyte heterogeneity in humans.
371 citations
Cites background from "Development of a Natural Model of C..."
...mice [39] did not result in detectable changes in the monocyte...
[...]
References
More filters
TL;DR: In this paper, the expression and recognition of a major histocompatibility complex (MHC) class I-related molecule, MICA, matches this localization, and the closely related MICB were recognized by intestinal epithelial T cells expressing diverse Vδ1 γδ TCRs.
Abstract: T cells with variable region Vδ1 γδ T cell receptors (TCRs) are distributed throughout the human intestinal epithelium and may function as sentinels that respond to self antigens. The expression of a major histocompatibility complex (MHC) class I–related molecule, MICA, matches this localization. MICA and the closely related MICB were recognized by intestinal epithelial T cells expressing diverse Vδ1 γδ TCRs. These interactions involved the α1α2 domains of MICA and MICB but were independent of antigen processing. With intestinal epithelial cell lines, the expression and recognition of MICA and MICB could be stress-induced. Thus, these molecules may broadly regulate protective responses by the Vδ1 γδ T cells in the epithelium of the intestinal tract.
1,080 citations
TL;DR: It is indicated that IL-12 plays an essential role in regulating IFNγ production and in facilitating normal DTH responses and other phenomena associated with Th1 responses and cell-mediated immunity, i.e., IL-2 secretion and CTL generation, were not compromised in the absence of IL- 12.
984 citations
TL;DR: Results provide formal evidence that, in contrast to recognition of major histocompatibility complex-bound peptide antigens by αβ T cells, human γδ T cells can recognize naturally occurring small non-peptidic antIGens.
Abstract: T lymphocytes express either alpha beta or gamma delta T-cell receptor heterodimers. Most alpha beta T cells recognize antigenic peptides bound to major histocompatibility complex molecules but the antigen recognition and biological function of gamma delta T cells is unknown. A major human gamma delta T-cell subset expressing V gamma 2 and V delta 2 germline genes, but having diverse junctional sequences, is found in human mycobacterial lesions and responds in vitro to antigens of bacteria and parasites. In addition, certain haematopoietic tumour cells are specifically recognized and lysed by these T cells. V gamma 2V delta 2-bearing T cells were shown to recognize mycobacterial antigens that are protease resistant and phosphatase sensitive. Because of the difficulty in isolating natural antigens from mycobacterial culture filtrates or extracts, we synthesized a series of monoalkyl phosphates, and found that some, particularly monoethyl phosphate, could mimic the activity of mycobacterial antigens in stimulating these gamma delta T cells. Here we report the identification of natural antigens produced by mycobacteria recognized by human V gamma 2V delta 2-bearing T cells as isopentenyl pyrophosphate and related prenyl pyrophosphate derivatives, compounds involved in the synthesis of complex polyisoprenoid compounds in microbial and mammalian cells. Substitution of phosphate for the pyrophosphate moiety, or elimination of the double bond, greatly reduced antigenic activity of these compounds. These results provide formal evidence that, in contrast to recognition of major histocompatibility complex-bound peptide antigens by alpha beta T cells, human gamma delta T cells can recognize naturally occurring small non-peptidic antigens.
956 citations
TL;DR: In this article, the authors used flow cytometry to identify the presence of intracellular cytokines (cytoflow) and analyse T-cell production of IFN-gamma and IL-4 from mice infected with Listeria monocytogenes or Nippostrongylus brasiliensis.
Abstract: Exposure to various pathogens can stimulate at least two patterns of cytokine production by CD4-positive T cells. Responses that result in secretion of interferon-gamma (IFN-gamma), lymphotoxin and interleukin-2 (IL-2) are classified as T-helper-1 (Th1); CD4+ T-cell production of IL-4, IL-5, IL-9, IL-10 and IL-13 is called a T-helper-2 response (Th2). Differentiation of CD4+ T cells into either Th1 or Th2 cells is influenced by the cytokine milieu in which the initial antigen priming occurs. Here we use flow cytometry to identify the presence of intracellular cytokines (cytoflow) and analyse T-cell production of IFN-gamma and IL-4 from mice infected with Listeria monocytogenes or Nippostrongylus brasiliensis. We show that T cells bearing gamma delta receptors discriminate early in infection between these two pathogens by producing cytokines associated with the appropriate T-helper response. Our results demonstrate that gamma delta T cells are involved in establishing primary immune responses.
663 citations
TL;DR: Distribution du sang dans la peau, agregation des plaquettes et vasoconstriction, coagulation, inflammation and hemostase, immunite, role de la salive chez les arthropodes hematophages.
Abstract: Distribution du sang dans la peau, agregation des plaquettes et vasoconstriction, coagulation, inflammation et hemostase, immunite, role de la salive chez les arthropodes hematophages. Coevolution des hotes et leurs ectoparasites
553 citations
"Development of a Natural Model of C..." refers background in this paper
...E xperimental models of leishmaniasis have only rarely attempted to reproduce the biology of natural transmission, including a consideration of ( a ) dose—sand flies inoculate low numbers of parasites, variably estimated at 10–1,000 metacyclic promastigotes (1); ( b ) saliva—parasites are coinoculated with small amounts of sand fly saliva that contain antihemostatic (2) and potentially immunomodulatory (3, 4) molecules that facilitate blood feeding; and ( c ) site of inoculation—infection is initiated in the skin, which is organized as specialized dermal and epidermal compartments containing unique cells such as keratinocytes, dendritic epidermal T cells (DETC), 1 and Langerhans’ cells that enable it to deal with the hostile external environment to which it is frequently exposed (5)....
[...]
...Blood sucking arthropods, including infected sand flies capable of egesting Leishmania, will salivate into the skin in order to locate blood and maintain its flow during ingestion (2)....
[...]