Limits...
Leishmania mexicana infection induces IgG to parasite surface glycoinositol phospholipids that can induce IL-10 in mice and humans.

Buxbaum LU - PLoS Negl Trop Dis (2013)

Bottom Line: These changes decrease IFN-γ from T cells and nitric oxide production in infected cells, which are both required for Leishmania control.Several groups have been unsuccessful in identifying amastigote surface proteins that bind IgG.Further characterization of the target glycolipids will have important implications for drug and vaccine development and will elucidate the poorly understood role of glycolipids in the immunology of infections.

View Article: PubMed Central - PubMed

Affiliation: Philadelphia Research and Education Foundation, Philadelphia, Pennsylvania, United States of America. buxbaum17@hotmail.com

ABSTRACT
Infection with the intracellular protozoan parasite Leishmania mexicana causes chronic disease in C57BL/6 mice, in which cutaneous lesions persist for many months with high parasite burdens (10(7)-10(8) parasites). This chronic disease process requires host IL-10 and FcγRIII. When Leishmania amastigotes are released from cells, surface-bound IgG can induce IL-10 and suppress IL-12 production from macrophages. These changes decrease IFN-γ from T cells and nitric oxide production in infected cells, which are both required for Leishmania control. However, antibodies targets and the kinetics of antibody production are unknown. Several groups have been unsuccessful in identifying amastigote surface proteins that bind IgG. We now show that glycoinositol phospholipids (GIPLs) of L. mexicana are recognized by mouse IgG1 by 6 weeks of infection, with a rapid increase between 12 and 16 weeks, consistent with the timing of chronic disease in C57BL/6 mice vs. healing in FcγRIII-deficient mice. A single prominent spot on TLC is recognized by IgG, and the glycolipid is a glycosyl phosphatidylinositol containing a branched mannose structure. We show that the lipid structure of the GIPL (the sn-2 fatty acid) is required for antibody recognition. This GIPL is abundant in L. mexicana amastigotes, rare in stationary-phase promastigotes, and absent in L. major, consistent with a role for antibodies to GIPLs in chronic disease. A mouse monoclonal anti-GIPL IgG recognizes GIPLs on the parasite surface, and induces IL-10 from macrophages. The current work also extends this mouse analysis to humans, finding that L. mexicana-infected humans with localized and diffuse cutaneous leishmaniasis have antibodies that recognize GIPLs, can bind to the surface of amastigotes, and can induce IL-10 from human monocytes. Further characterization of the target glycolipids will have important implications for drug and vaccine development and will elucidate the poorly understood role of glycolipids in the immunology of infections.

Show MeSH

Related in: MedlinePlus

Opsonization with early and late L. mexicana anti-sera.Sera from mice infected with L. mexicana for 9 wks (n = 5) and 27 wks (n = 6) were used to opsonize L. mexicana axenic amastigotes. A. Parasite surface mouse-IgG1 and -IgG2a/c were detected by flow cytometry. Unopsonized amastigotes (thin black), uninfected serum (thick black), and serum from infected mice (colored) are shown. B. Data from A with Geometric Mean Fluorescence Intensity (GMFI) are shown for each time point, with mean and SE. P = 6×10−5 for the difference between 9- and 27-wk samples. Data are representative of 2 similar experiments.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3649955&req=5

pntd-0002224-g002: Opsonization with early and late L. mexicana anti-sera.Sera from mice infected with L. mexicana for 9 wks (n = 5) and 27 wks (n = 6) were used to opsonize L. mexicana axenic amastigotes. A. Parasite surface mouse-IgG1 and -IgG2a/c were detected by flow cytometry. Unopsonized amastigotes (thin black), uninfected serum (thick black), and serum from infected mice (colored) are shown. B. Data from A with Geometric Mean Fluorescence Intensity (GMFI) are shown for each time point, with mean and SE. P = 6×10−5 for the difference between 9- and 27-wk samples. Data are representative of 2 similar experiments.

Mentions: We have shown by ELISA that at early times there is an IgG1 response and later an IgG2a/c response in B6 mice to parasite antigens (freeze-thawed Ag). Here we showed that this same kinetics occur with amastigote surface-binding IgG. Strong IgG1 and negligible IgG2a/c are seen at 9 wks post-infection, but both IgG1 and IgG2a/c to surface epitopes are present late in infection (27 wks) (Fig. 2A). The geometric mean fluorescence intensities (GMFI) are shown (Fig. 2B), with significant differences between 9- and 27-wk IgG2a/c binding, but no difference in IgG1 binding at the two time points. We have already shown that IgG, when bound to L. mexicana amastigotes, can induce IL-10 from macrophages stimulated with lipopolysaccharide [16], and that IL-10 is required for chronic disease caused by infection with this parasite [14].


Leishmania mexicana infection induces IgG to parasite surface glycoinositol phospholipids that can induce IL-10 in mice and humans.

Buxbaum LU - PLoS Negl Trop Dis (2013)

Opsonization with early and late L. mexicana anti-sera.Sera from mice infected with L. mexicana for 9 wks (n = 5) and 27 wks (n = 6) were used to opsonize L. mexicana axenic amastigotes. A. Parasite surface mouse-IgG1 and -IgG2a/c were detected by flow cytometry. Unopsonized amastigotes (thin black), uninfected serum (thick black), and serum from infected mice (colored) are shown. B. Data from A with Geometric Mean Fluorescence Intensity (GMFI) are shown for each time point, with mean and SE. P = 6×10−5 for the difference between 9- and 27-wk samples. Data are representative of 2 similar experiments.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3649955&req=5

pntd-0002224-g002: Opsonization with early and late L. mexicana anti-sera.Sera from mice infected with L. mexicana for 9 wks (n = 5) and 27 wks (n = 6) were used to opsonize L. mexicana axenic amastigotes. A. Parasite surface mouse-IgG1 and -IgG2a/c were detected by flow cytometry. Unopsonized amastigotes (thin black), uninfected serum (thick black), and serum from infected mice (colored) are shown. B. Data from A with Geometric Mean Fluorescence Intensity (GMFI) are shown for each time point, with mean and SE. P = 6×10−5 for the difference between 9- and 27-wk samples. Data are representative of 2 similar experiments.
Mentions: We have shown by ELISA that at early times there is an IgG1 response and later an IgG2a/c response in B6 mice to parasite antigens (freeze-thawed Ag). Here we showed that this same kinetics occur with amastigote surface-binding IgG. Strong IgG1 and negligible IgG2a/c are seen at 9 wks post-infection, but both IgG1 and IgG2a/c to surface epitopes are present late in infection (27 wks) (Fig. 2A). The geometric mean fluorescence intensities (GMFI) are shown (Fig. 2B), with significant differences between 9- and 27-wk IgG2a/c binding, but no difference in IgG1 binding at the two time points. We have already shown that IgG, when bound to L. mexicana amastigotes, can induce IL-10 from macrophages stimulated with lipopolysaccharide [16], and that IL-10 is required for chronic disease caused by infection with this parasite [14].

Bottom Line: These changes decrease IFN-γ from T cells and nitric oxide production in infected cells, which are both required for Leishmania control.Several groups have been unsuccessful in identifying amastigote surface proteins that bind IgG.Further characterization of the target glycolipids will have important implications for drug and vaccine development and will elucidate the poorly understood role of glycolipids in the immunology of infections.

View Article: PubMed Central - PubMed

Affiliation: Philadelphia Research and Education Foundation, Philadelphia, Pennsylvania, United States of America. buxbaum17@hotmail.com

ABSTRACT
Infection with the intracellular protozoan parasite Leishmania mexicana causes chronic disease in C57BL/6 mice, in which cutaneous lesions persist for many months with high parasite burdens (10(7)-10(8) parasites). This chronic disease process requires host IL-10 and FcγRIII. When Leishmania amastigotes are released from cells, surface-bound IgG can induce IL-10 and suppress IL-12 production from macrophages. These changes decrease IFN-γ from T cells and nitric oxide production in infected cells, which are both required for Leishmania control. However, antibodies targets and the kinetics of antibody production are unknown. Several groups have been unsuccessful in identifying amastigote surface proteins that bind IgG. We now show that glycoinositol phospholipids (GIPLs) of L. mexicana are recognized by mouse IgG1 by 6 weeks of infection, with a rapid increase between 12 and 16 weeks, consistent with the timing of chronic disease in C57BL/6 mice vs. healing in FcγRIII-deficient mice. A single prominent spot on TLC is recognized by IgG, and the glycolipid is a glycosyl phosphatidylinositol containing a branched mannose structure. We show that the lipid structure of the GIPL (the sn-2 fatty acid) is required for antibody recognition. This GIPL is abundant in L. mexicana amastigotes, rare in stationary-phase promastigotes, and absent in L. major, consistent with a role for antibodies to GIPLs in chronic disease. A mouse monoclonal anti-GIPL IgG recognizes GIPLs on the parasite surface, and induces IL-10 from macrophages. The current work also extends this mouse analysis to humans, finding that L. mexicana-infected humans with localized and diffuse cutaneous leishmaniasis have antibodies that recognize GIPLs, can bind to the surface of amastigotes, and can induce IL-10 from human monocytes. Further characterization of the target glycolipids will have important implications for drug and vaccine development and will elucidate the poorly understood role of glycolipids in the immunology of infections.

Show MeSH
Related in: MedlinePlus