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The Journal of Immunology, 2001, 166: 3416-3422.
Copyright © 2001 by The American Association of Immunologists

General Suppression of Macrophage Gene Expression During Leishmania donovani Infection1

Sureemas Buates* and Greg Matlashewski2,{dagger}

* Institute of Parasitology, McGill University, St. Anne de Bellevue, Quebec, Canada; and {dagger} Department of Microbiology and Immunology, McGill University, Montreal, Canada


   Abstract
Top
 Abstract
Introduction
 Materials and Methods
 Results
 Discussion
 References
 
Within the mammalian host, Leishmania donovani is an obligatory intracellular protozoan that resides and multiplies exclusively in the phagolysosomes of macrophages. The outcome of this infection is governed by the interaction between Leishmania and macrophage molecules that ultimately effect the expression of genes within both cells. To explore the effect of this intracellular infection on macrophage gene expression, a cDNA expression array analysis was performed to compare gene expression profiles in noninfected and L. donovani-infected macrophages. In this manner, it was possible to examine the effect of infection on the expression of several hundred well-characterized host cell genes in an unbiased manner. Interestingly, ~40% of the genes whose expression was detected in macrophages were down-regulated during infection with L. donovani. However, several genes were also induced during the infection process, some of which could play a role in recruitment of additional macrophages to the site of infection. Taken together, the general suppression of gene expression in addition to the selective induction of key genes is likely to play an important role in allowing the parasite to survive and proliferate within its host macrophage cell.


   Introduction
Top
 Abstract
 Introduction
Materials and Methods
 Results
 Discussion
 References
 
Leishmania, the causative agent of human leishmaniasis, is a digenetic protozoan parasite that inhabits two highly specific hosts during its life cycle. In the midgut of the sandfly vector it multiplies as the extracellular flagellated promastigotes, and in the mammalian macrophages it survives and replicates intracellularly as the nonflagellated amastigotes in the phagolysosomes or parasitophorous vacuoles. Macrophages play an important role against invasive microorganisms including Leishmania and act as APCs during infection. In addition, macrophages are the effector cells that kill intracellular organisms including Leishmania once a protective Th1 cell immune response has been established (reviewed in Ref. 1). Therefore, during a Leishmania infection, macrophages not only serve as the host cells for this parasite, but they are also important effector cells for the killing of this organism. Therefore, the outcome of infection depends on the balance between the host ability to activate macrophage killing and the parasite ability to suppress or evade this host immune response.

During an established infection, Leishmania has developed mechanisms to subvert the macrophage microbicidal activity. For example, L. donovani amastigotes interfered with the expression of MHC II molecules following stimulation with IFN-{gamma} (reviewed in Ref. 2) and the B7-1 costimulatory molecule (3, 4, 5). This infection also results in reduced expression of IL-1 and TNF-{alpha} genes following stimulation with LPS or Staphylococcus aureus (6, 7, 8). Several reports have also documented an impairment in signal transduction in infected macrophages (9, 10, 11, 12).

Although these and other studies have examined the expression of a variety of specific genes in response to various macrophage ligands, little is known about what happens to global host cell gene expression when Leishmania is multiplying within macrophages. Therefore, we have undertaken to compare the expression of 588 well-characterized genes in noninfected and L. donovani-infected macrophages using a cDNA expression array analysis. In this manner, it was possible to obtain a novel perspective on the effect of infection on macrophage gene expression. Of particular interest, L. donovani infection resulted in suppression of ~40% of the cellular genes whose expression was detectable in macrophages, although housekeeping genes were expressed at equal levels in infected and noninfected cells. In addition, L. donovani infection did also result in an up-regulation of a small number of genes in macrophages including macrophage inflammatory proteins (MIP)3 1{alpha} and 1{beta}, which could result in the recruitment of new macrophages to the site of infection. The selective induction of such genes together with the widespread suppression of gene expression during infection likely plays key roles to ensure the suitability of the infected host cell for the parasite survival and replication.


   Materials and Methods
Top
 Abstract
 Introduction
 Materials and Methods
Results
 Discussion
 References
 
Preparation of bone marrow-derived macrophages (BMM)

BMM were obtained from femurs of 6- to 8-wk-old female BALB/c mice (Charles River Canada, St. Constant, Québec, Canada) as previously described (8, 10, 12) by flushing femurs with RPMI 1640 complete medium. These cells were incubated in tissue culture dishes (Nunc, Roskilde, Denmark) for 1 day at 37°C in 5% CO2 in moist air in RPMI 1640 complete medium containing 15% (v/v) L929 cell-conditioned medium as a source of M-CSF or CSF-1. After 1 day in culture, the immature nonadherent cells were transferred into new polystyrene culture dishes (Falcon 1029; Fisher, Montreal, Canada), which were weakly adherent for macrophages and were cultured in 15% CSF-1 to induce macrophage differentiation for 7 days. The resulting BMM population was made quiescent by culturing them in CSF-1-free medium for 18 h. Cell viability after scraping was determined by trypan blue exclusion assay, and live cells were counted with a hemocytometer. The quiescent BMM (106 cells/ml) in polystyrene tubes were infected with amastigotes of 1S2D strain of L. donovani at a ratio of 4:1 amastigotes per macrophage for 12 h. Noningested parasites were removed by three washed at low speed (225 x g) with warm RPMI 1640 complete medium. Infection levels were determined by microscopic examination of Giemsa-stained cytocentrifuge preparations. Infected cells were cultured for 4 days before total RNA isolation, at a time when amastigotes are actively proliferating inside the macrophages.

RNA isolation

Total RNA from noninfected and infected BMM was isolated and subjected to DNase treatment to eliminate genomic DNA contamination using Atlas Pure Total RNA Labeling System (Clontech Laboratories, Palo Alto, CA). The integrity of total RNA was confirmed by agarose gel electrophoresis.

Gene array analysis

Gene expression was analyzed using the Atlas Mouse cDNA Expression Array (Clontech Laboratories). The basic principal of this technique can be viewed as reverse Northern blotting using several hundred well-characterized and organized cDNA probes. Poly(A)+ RNA was enriched from total RNA using Atlas Pure Total RNA Labeling System (Clontech). Poly(A)+ RNA enrichment samples were reverse transcribed in the presence of reverse transcriptase (Clontech Laboratories) and [{alpha}-32P]dATP. The generated radiolabeled cDNA probes from noninfected and infected cells with a specific radioactivity of {approx}1.3 x 106 cpm were purified from unincorporated nucleotides and hybridized to identical membranes containing the mouse cDNA arrays. Each cDNA array contains 588 previously characterized mouse genes. Each of the cDNAs on the array contains 200–600 bp of unique sequences lacking a poly(A) tail, repetitive elements, or highly homologous sequences to minimize cross-hybridization and nonspecific bindings of the labeled cDNA probes. The amount of each cDNA fragment on the array contains 10 ng of DNA immobilized in two adjacent dots, and the strength of the signal is proportional to the level of the mRNA. Following hybridization, high-stringency washes were performed and the membranes were subjected to autoradiography. The hybridization pattern was analyzed with the AtlasImage 1.1 software package (Clontech Laboratories) specifically designed for analyzing Atlas Array data. Approximately 50% of the RNA in the infected cell was derived from L. donovani as determined by parasite ribosomal RNA levels relative to the macrophage ribosomal RNA levels. Therefore, two times as much RNA was used from the infected cell as from the noninfected cell to prepare the hybridization probes. As detailed in Results, the hybridization intensity levels were carefully standardized using several highly expressed housekeeping genes whose respective expression levels were the same in the infected and noninfected cells.

Northern blot analysis

Total RNA from noninfected and infected BMM was isolated using Atlas Pure Total RNA Labeling System (Clontech Laboratories). Ten micrograms of total cellular RNA was denatured by glyoxal at 50°C for 1 h and chilled on ice for 5 min. One microgram of ethidium bromide was added to each sample before electrophoresis in 1% agarose gel to fractionate RNA as previously described (13). Following electrophoresis, RNA was blotted on to Hybond-N nylon membrane (Amersham, Little Chalfont, U.K.) as recommended by the manufacturer. The RNA was cross-linked to the membrane using UV irradiation and prehybridized with 20x SSC phosphate/EDTA, 50x Denhardt, 50% formamide, 10% SDS, and 10 mg/ml denatured salmon sperm DNA at 42°C for 3 h. Hybridization was performed at 42°C for 18 h with probes purified from agarose gels and nick translated in the presence of 125 µCi [{alpha}-32P]dCTP (ICN Biochemicals, Québec, Canada). Membranes were washed once at room temperature and twice at 55°C with 0.5x SSC for 30 min each and autoradiographed at -70°C in cassettes on Kodak Bio Max MS films (Rochester, NY) with Bio Max MS intensifying screens. The mouse MIP-1{beta}, monocyte chemoattractant protein (MCP)-1 receptor A (MCP-1RA), and CD40 probes used were the 326-, 297-, and 337-bp cDNA fragment, respectively, (Clontech Laboratories). To ensure that equal amounts of RNA were analyzed, blots were stripped, rehybridized with a radiolabeled cDNA probe for actin (1.25 kb PstI of pBA-1), washed, and again subjected to autoradiography. When quantified by scanning densitometry, multiple exposures were used to ensure that all signals were within the linear response range of the film.


   Results
Top
 Abstract
 Introduction
 Materials and Methods
 Results
Discussion
 References
 
The objective of this study was to investigate the effect of L. donovani infection on basal gene expression in macrophages at a time when the parasite is actively multiplying in these cells. The rationale for selecting BMM and the 4-day time point of infection is based on several previous studies (14, 15, 16, 17). First, these are nontumorigenic primary macrophages that become 100% infected with L. donovani, and the highest level of amastigote proliferation in these cells is reached at 4 days following infection as detailed in our previous studies (14, 15). Second, although the infected macrophages are maintained in the absence of growth factor, the cells remain viable because the infection process effectively inhibits apoptosis as we have previously described (16, 17). Therefore, these observations confirmed the suitability of this experimental system to examine the effect of L. donovani infection on macrophage gene expression.

An equal number of viable noninfected and infected BMM were used for the RNA extraction. RNA was isolated from noninfected BMM that were made quiescent through culturing in the absence of growth factor for 18 h before harvesting and from BMM that were infected for 4 days. Poly(A)-enriched RNA was used as the template to prepare the {alpha}-32P-radiolabeled cDNA probes. The probes were then hybridized to two identical gene array membranes that contained an extensive representation of previously characterized cellular genes involved in a variety of functions and clustered in six quadrants as follows: 1) oncogenes, tumor suppressor genes, and cell cycle regulators; 2) stress response genes, ion channels and transport genes, and intracellular signal transduction modulators and effectors; 3) apoptosis-related genes and genes involved in DNA synthesis, DNA repair, and DNA recombination; 4) transcriptional factors and general DNA binding proteins; 5) cell surface receptors, and cell adhesion molecules; and 6) cell-cell communication factors.

To quantify the level of gene expression, the membranes were subjected to autoradiography and the relative intensity for each gene was analyzed by using AtlasImage 1.1 software as detailed in Materials and Methods. To compare transcript levels in infected and noninfected cells, appropriate internal reference genes were used for standardization. Conventionally, so called housekeeping genes are used as internal standards for which we examined the genes encoding ubiquitin, G3PDH, {beta}-actin, and ribosomal protein S29. As shown in Fig. 1Go, which focuses only on these four internal standard genes, the transcript levels were equal in the infected and noninfected cells. Based on these control data showing a similar level of housekeeping gene expression in the infected and noninfected cells, it was next possible to examine the expression of the other genes on the array.



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  		FIGURE 1. Gene expression profiles of house-keeping genes on the gene array from noninfected and L. donovani-infected cells in upper and lower panels, respectively. The location of ubiquitin, G3PDH, {beta}-actin, and ribosomal protein S29 genes are indicated.

 
As is visually apparent in Fig. 2Go, the level of many of the transcripts was reduced in the infected cells relative to the noninfected cells. Of the 245 genes that had detectable expression in the noninfected macrophages, 90 showed a reduced level of expression by at least 2-fold in the infected macrophages. Therefore, 37% of the genes with detectable expression in the noninfected macrophages were down-regulated in the infected cells, and these are listed in Table IGo. Based on this observation, there appears to be a general down-modulation in macrophage gene expression relative to the housekeeping genes at a time when the infection has established and the parasite is actively multiplying.



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  		FIGURE 2. Gene expression profiles of normal and L. donovani-infected cells are presented in upper and lower panels, respectively. Total RNA was isolated from either normal or L. donovani-infected cells. Poly(A)+ RNA was enriched from total RNA and was used as a template to synthesize {alpha}-32P-radiolabeled cDNA probes of equal specific activity. The cDNA probes were hybridized to two identical gene array membranes. The membranes were exposed to x-ray films and autoradiographed. The membranes contain 588 genes, divided into six functional groups: oncogenes, tumor suppressor genes, and cell cycle regulators (A); stress response genes, ion channels and transport genes, and intracellular signal transduction modulators and effectors (B); apoptosis-related genes and genes involved in DNA synthesis, DNA repair, and DNA recombination (C); transcriptional factors and general DNA binding proteins (D); cell surface receptors, and cell adhesion molecules (E); and cell-cell communication factors (F). The housekeeping genes used as internal references are in the G row. The location of the ubiquitin, G3PDH, {beta}-actin, and ribosomal protein S29 genes are indicated.

 

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  		Table I. Genes down-regulated in L. donovani-infected cellsa

 
Although the majority of differences represented a reduction in expression in the infected cells, there were several interesting examples where genes were up-regulated in the infected cells, and these are shown in Table IIGo. For example MIP-1{alpha} and MIP-1{beta} genes were up-regulated in the infected cells. The products from these genes could play a major role in the recruitment of additional macrophages to the site of infection to increase the number of potential host cells for the parasite to infect.


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  		Table II. Genes upregulated in L. donovani-infected cellsa

 
However, it was important to verify that the data generated with the cDNA array analysis accurately reflected the alteration in transcript level resulting from infection. Therefore, Northern blot analysis was conducted to analyze the expression of three genes whose levels were elevated (MIP-1{beta}) or down-regulated (MCP-1RA and CD40) during infection. As shown in Fig. 3Go, the MIP-1{beta} mRNA was significantly higher in the infected cells compared with the noninfected cells, and this is consistent with the gene array analysis (Fig. 2GoF, coordinates 3f). Northern bolt analysis of MCP-1RA and CD40 genes also strongly supported the results obtained from the gene array, which likewise showed that these genes were down-regulated during infection. Taken together, the Northern blot analysis confirmed that the gene array approach accurately reflected cellular transcript levels in the infected cells.



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  		FIGURE 3. Northern blot analysis of the MIP-1{beta}, MCP-1RA, and CD40 mRNAs. Total RNA was isolated from normal or L. donovani-infected BMM. The RNA samples were fractionated on agarose gel and then subjected to Northern blotting analysis using {alpha}-32P-radiolabeled cDNA probes corresponding to the indicated genes.

 

   Discussion
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
References
 
Although a considerable amount of research has been conducted to compare molecular changes in macrophages associated with Leishmania infection, this is the first study to examine global changes in gene expression during a productive infection with this parasite. The major observations reported within are that: 1) infection resulted in a general suppression of gene expression in which some 37% of the detectable expressed genes were down-regulated during infection; 2) infection also resulted in the induction of several genes, some of which would be expected to enhance the infection process including the MIP genes. These observation contribute considerably to define the host cell response during infection and provide a foundation for future studies to define the mechanisms involved. In addition, this could provide novel drug targets such as for example inhibiting MIP-1{beta} to see whether this would reduce the level or spread of infection.

The present study was undertaken to determine the effect of Leishmania infection of global gene expression in host macrophages. For this purpose, a gene array analysis using an appropriate representation of well-characterized genes was undertaken in this study. An unexpected result was the general suppression of a significant percentage of genes during infection. It is noteworthy that this result would also be expected if the analysis was conducted on a microarray containing the entire genome. Although this study was also able to identify the induction of several interesting genes during infection, future studies using a micoarray approach will likely identify significantly more induced genes. Nevertheless, it is clear that the experimental approach described within has been successful in providing novel and significant new insight into this infection process.

Although a significant percentage of the expressed genes were down-regulated during infection, the majority of these were down-regulated by about 2-fold. A 2-fold down-regulation of a few genes may not have a significant effect on the host cell. However, as demonstrated within, almost 40% of the genes whose expression was detectable were down-regulated by 2-fold or greater. Because of this large number of down-regulated genes, this would be expected to have a significant overall effect on the host cell. The down-regulation of these genes likely reduces the capacity of the cell to function normally and thus contributes to the ability of the amastigotes to proliferate in the compromised cell.

However, it is noteworthy that several genes were down-regulated to a much greater extent than 2-fold, and it is of interest to consider the potential role of these genes during infection. For example, the CD40 gene was down-regulated by about 5-fold, and it has been previously shown that activation of macrophages by Th1 cells during the killing of intracellular Leishmania required the interaction between CD40 on the macrophages and the CD40 ligand on the Th1 lymphocytes (18, 19, 20). In addition, CD40 deficiency in resistant mice rendered these animals susceptible to infection with Leishmania major (21). Therefore, down-regulation of expression of the CD40 gene during infection as demonstrated within would enhance the survival of Leishmania.

There was also a more significant reduction in the expression of the MCP-1RA gene (also referred to as CCR-2) in infected cells as determined by the gene array analysis, and this was also consistent with the Northern blot data. This gene encodes the receptor for the MCP (22). MCP-1RA (CCR-2) knockout mice have been characterized with an abnormality in monocyte/macrophage migration and were defective in the production of Th1-generating cytokines including IFN-{gamma} (23). Therefore, down-regulation of MCP-1RA gene expression could also enhance parasite survival through impairing migration of the infected cell and reducing the ability to mount an anti-Leishmania Th1 immune response. Finally, the proapoptotic gene BAD was also significantly down-regulated, and this is consistent with our previous observation that infection results in an inhibition of apoptosis (16). It would be of interest to undertake a larger examination of genes involved in the apoptosis process in these cells.

It is also interesting to consider some of the genes that were significantly induced during infection such as MIP-1{alpha} and MIP-1{beta}. The MIP-1{alpha} and MIP-1{beta} gene products are potent chemoattractants for monocyte/macrophages. These cytokines may be important in attracting the noninfected immature monocyte/macrophages, which could represent a safe target into the site of infection because these immature cells can be infected but would not be expected to kill the parasite.

It will be important in future studies to determine the mechanism in which both the suppression and induction of gene expression occurs simultaneously during infection. For example, the general suppression of gene expression could be due in part to the impairment of signal transduction pathways of the parasite including the protein kinase C (9, 10, 11, 12, 24). In fact, this study showed that infection with L. donovani down-regulated many of proteins that are important in the intracellular signal transduction pathway including mitogen-activated protein kinase kinases 1 and 3 as shown in Table IGo. Moreover, infection also resulted in a suppression of general transcription factors including NF-{kappa}B p105 and RelB. These proteins are all members of the NF-{kappa}B/Rel family of transcription factors that regulate the expression of a variety of genes involved in immune response, inflammatory responses, and cellular growths (for example, GM-CSF, IL-2, IL-6, IL-8, etc.) (25). Taken together, the results from this study reveal that this infection has a remarkable overall effect on cellular gene expression, and this could provide an explanation why Leishmania is able to survive in perhaps the most hostile cellular environment in the mammalian host, the macrophage cell.


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  		Table 1A. Continued

 

   Footnotes
 
1 This work was funded by the Canadian Institutes of Health Research and the United Nations Development Program/World Bank/World Health Organization special program for research and training in tropical diseases. G.M. is the recipient of a Medical Research Council Senior Scientist Award. Back

2 Address correspondence and reprint requests to Dr. Greg Matlashewski, Department of Microbiology and Immunology, McGill University, 3775 University Street, Montreal, Canada H3A 2B4. Back

3 Abbreviations used in this paper: MIP, macrophage inflammatory protein; BMM, bone marrow-derived macrophage; MCP, monocyte chemoattractant protein; MCP-1RA, MCP-1 receptor A. Back

Received for publication October 27, 2000. Accepted for publication December 21, 2000.


   References
Top
 Abstract
 Introduction
 Materials and Methods
 Results
 Discussion
 References
 

  1. Mauel, J.. 1996. Intracellular survival of protozoan parasites with special reference to Leishmania spp., Toxoplasma gondii and Trypanosoma cruzi. Adv. Parasitol. 38:1.[Medline]
  2. Reiner, N. E.. 1994. Altered cell signaling and mononuclear phagocyte deactivation during intracellular infection. Immunol. Today 15:374.[Medline]
  3. Kaye, P. M., N. J. Rogers, A. J. Curry, J. C. Scott. 1994. Deficient expression of co-stimulatory molecules on Leishmania-infected macrophages. Eur. J. Immunol. 24:2850.[Medline]
  4. Saha, B., G. Das, H. Vohra, N. K. Ganguly, G. C. Mishra. 1995. Macrophage-T cell interaction in experimental visceral leishmaniasis: failure to express costimulatory molecules on Leishmania-infected macrophages and its implication in the suppression of cell mediated immunity. Eur. J. Immunol. 25:2492.[Medline]
  5. Murphy, M. L., C. R. Engwerda, P. M. Gorak, P. M. Kaye. 1997. B7-2 blockade enhances T cell responses to Leishmania donovani. J. Immunol. 159:4460.[Abstract]
  6. Reiner, N. E.. 1987. Parasite accessory cell interactions in murine leishmaniasis. I. Evasion and stimulus-dependent suppression of the macrophage interleukin-1 response by Leishmania donovani. J. Immunol. 138:1919.[Abstract]
  7. Reiner, N. E., W. Ng, C. B. Wilson, W. R. McMaster, S. K. Burchett. 1990. Modulation of in vitro monocyte cytokine responses to Leishmania donovani: interferon-{gamma} prevents parasite-induced inhibition of interleukin-1 production and primes monocytes to respond to Leishmania by producing both tumor necrosis factor-{alpha} and interleukin-1. J. Clin. Invest. 85:1914.
  8. Descoteaux, A., G. Matlashewski. 1989. c-fos and tumor necrosis factor gene expression in Leishmania donovani-infected macrophages. Mol. Cell. Biol. 9:5223.[Abstract/Free Full Text]
  9. Moore, K. J., S. Labrecque, G. Matlashewski. 1993. Alteration of Leishmania donovani infection levels by selective impairment of macrophage signal transduction. J. Immunol. 150:4457.[Abstract]
  10. Descoteaux, A., S. J. Turco, D. L. Sacks, G. Matlashewski. 1991. Leishmania donovani lipophosphoglycan selectively inhibits signal transduction in macrophages. J. Immunol. 146:2747.[Abstract]
  11. Olivier, M., R. Brownsey, N. Reiner. 1992. Defective stimulus-response coupling in human monocytes infected with Leishmania donovani is associated with altered activation of protein kinase C. Proc. Natl. Acad. Sci. USA 89:7481.[Abstract/Free Full Text]
  12. Descoteaux, A., G. Matlashewski, S. J. Turco. 1992. Inhibition of macrophage protein kinase C-mediated protein phosphorylation by Leishmania donovani lipophosphoglycan. J. Immunol. 149:3008.[Abstract]
  13. Thomas, P. S.. 1980. Hybridization of denatured RNA and small DNA fragments transferred to nitrocellulose. Proc. Natl. Acad. Sci. USA 77:5201.[Abstract/Free Full Text]
  14. Moore, K., S. Labrecque, G. Matlashewski. 1993. Alteration of Leishmania donovani infection levels by selective impairment of macrophage signal transduction. J. Immunol. 150:4457.
  15. Buates, S., G. Matlashewski. 1999. Treatment of experimental leishmaniasis with the immunomodulators imiquimod and S-28463: efficacy and mode of action. J. Infect. Dis. 179:1485.[Medline]
  16. Moore, K., G. Matlashewski. 1994. Intracellular infection by Leishmania donovani inhibits macrophage apoptosis. J. Immunol. 152:2930.[Abstract]
  17. Moore, K., S. Turco, G. Matlashewski. 1994. Leishmania donovani infection enhances macrophage viability in the absence of exogenous growth factor. J. Leukocyte Biol. 55:91.[Abstract]
  18. Campbell, K. A., P. J. Ovendale, M. K. Kennedy, W. C. Fanslow, S. G. Reed, C. R. Maliszewski. 1996. CD40 ligand is required for protective cell-mediated immunity to Leishmania major. Immunity 4:283.[Medline]
  19. Soong, L., J. C. Xu, I. S. Grewal, P. Kima, J. Sun, Jr B. J. Longley, N. H. Ruddle, D. McMahon-Pratt, R. A. Flavell. 1996. Disruption of CD40-CD40 ligand interactions results in an enhanced susceptibility to Leishmania amazonensis infection. Immunity 4:263.[Medline]
  20. Heinzel, F. P., R. M. Rerko, A. M. Hujer. 1998. Underproduction of interleukin-12 in susceptible mice during progressive leishmaniasis is due to decreased CD40 activity. Cell. Immunol. 184:129.[Medline]
  21. Kamanaka, M., P. Yu, T. Yasui, K. Yoshida, T. Kawabe, T. Horii, T. Kishimoto, H. Kikutani. 1996. Protective role of CD40 in Leishmania major infection at two distinct phases of cell-mediated immunity. Immunity 4:275.[Medline]
  22. Charo, I. F., S. J. Myers, A. Herman, C. Franci, A. J. Connolly, S. R. Coughlin. 1994. Molecular cloning and functional expression of two monocyte chemoattractant protein 1 receptors reveals alternative splicing of the carboxyl-terminal tails. Proc. Natl. Acad. Sci. USA 91:2752.[Abstract/Free Full Text]
  23. Boring, L., J. Gosling, S. W. Chensue, S. L. Kunkel, R. V. J. Farese, H. F. Broxmeyer, I. F. Charo. 1997. Impaired monocyte migration and reduced type 1 (Th1) cytokine responses in C-C chemokine receptor 2 knockout mice. J. Clin. Invest. 100:2552.[Medline]
  24. Giorgione, J. R., S. J. Turco, R. M. Epand. 1996. Transbilayer inhibition of protein kinase C by the lipophosphoglycan from Leishmania donovani. Proc. Natl. Acad. Sci. USA 93:11634.[Abstract/Free Full Text]
  25. Jr Baldwin, A. S.. 1996. The NF-{kappa}B and I{kappa}-B proteins: new discoveries and insights. Annu. Rev. Immunol. 14:649.[Medline]



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Impaired Expression of Inflammatory Cytokines and Chemokines at Early Stages of Infection with Leishmania amazonensis
Infect. Immun., August 1, 2003; 71(8): 4278 - 4288.
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D. Chaussabel, R. T. Semnani, M. A. McDowell, D. Sacks, A. Sher, and T. B. Nutman
Unique gene expression profiles of human macrophages and dendritic cells to phylogenetically distinct parasites
Blood, July 15, 2003; 102(2): 672 - 681.
[Abstract] [Full Text] [PDF]

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