title: Impaired expression of inflammatory cytokines and chemokines at early stages of infection with Leishmania amazonensis.
abstract: Infection of mice with Leishmania major results in disease progression or resolution, largely depending on the genetic backgrounds of the mouse strains. Infection with Leishmania amazonensis, on the other hand, causes progressive cutaneous lesions in most inbred strains of mice. We hypothesized that deficient activation of early immune responses contributes to the pathogenesis in L. amazonensis-infected mice. To distinguish early molecular events that determine the outcome of Leishmania infections, we examined cytokine gene expression in C57BL/6 mice infected with either L. amazonensis or L. major (a healing model). After 2 to 4 weeks, L. amazonensis-infected mice had significantly delayed and depressed expression of inflammatory cytokines (interleukin-12 [IL-12], gamma interferon, IL-1 alpha, IL-1 beta), CC chemokines (CC chemokine ligand 3 [CCL3]/macrophage inflammatory protein 1 alpha [MIP-1 alpha], CCL4/MIP-1 beta, CCL5/RANTES, MIP-2), and chemokine receptors (CCR1, CCR2, CCR5) in foot tissues and draining lymph nodes compared to the expression in L. major-infected controls. These findings correlated with defective T-cell responsiveness to parasite stimulation in vivo and in vitro. Adoptive transfer of L. amazonensis-specific Th1 cells prior to infection overcame the immune defects of the animals, leading to complete control of the disease. Studies with gene knockout mice suggested that IL-10, but not IL-4, contributed partially to compromised immunity in L. amazonensis-infected hosts. The data suggest that there is impairment in multiple immune functions at early stages of infection with L. amazonensis parasites and provide a compelling rationale to explore immune augmentation as an intervention in American cutaneous leishmaniasis.
authors.affiliation: Department of Microbiology and Immunology, WHO Center for Tropical Diseases, Sealy Center for Vaccine Development, University of Texas Medical Branch at Galveston, Galveston, Texas 77555-1070, USA.
authors.forename: Jiaxiang
authors.initials: J
authors.lastname: Ji
authors.forename: Jiaren
authors.initials: J
authors.lastname: Sun
authors.forename: Lynn
authors.initials: L
authors.lastname: Soong
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D000953:Antigens, Protozoan; D019742:Chemokines, CC / Q000096:biosynthesis* / Q000235:genetics*; D016207:Cytokines / Q000096:biosynthesis* / Q000235:genetics*; D005260:Female; D066298:In Vitro Techniques; D018836:Inflammation Mediators / Q000378:metabolism*; D016753:Interleukin-10 / Q000172:deficiency / Q000235:genetics / Q000276:immunology; D015847:Interleukin-4 / Q000172:deficiency / Q000235:genetics / Q000276:immunology; D007894:Leishmania mexicana; D016774:Leishmaniasis, Diffuse Cutaneous / Q000209:etiology / Q000235:genetics* / Q000276:immunology*; D051379:Mice; D008807:Mice, Inbred BALB C; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D018417:Th1 Cells / Q000276:immunology
chemical_list: D000953:Antigens, Protozoan; D019742:Chemokines, CC; D016207:Cytokines; D018836:Inflammation Mediators; D016753:Interleukin-10; D015847:Interleukin-4