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Suppression of adaptive immunity to heterologous antigens during Plasmodium infection through hemozoin-induced failure of dendritic cell function.

Millington OR, Di Lorenzo C, Phillips RS, Garside P, Brewer JM - J. Biol. (2006)

Bottom Line: This effect on T-cell activation can be transferred to uninfected recipients by DCs isolated from infected mice.Significantly, T cells activated by these DCs subsequently lack effector function, as demonstrated by a failure to migrate to lymphoid-organ follicles, resulting in an absence of B-cell responses to heterologous antigens.Fractionation studies show that hemozoin, rather than infected erythrocyte (red blood cell) membranes, reproduces the effect of intact infected red blood cells on DCs.

View Article: PubMed Central - HTML - PubMed

Affiliation: Division of Immunology, Infection and Inflammation, University of Glasgow, Glasgow G11 6NT, UK. owain.millington@strath.ac.uk

ABSTRACT

Background: Dendritic cells (DCs) are central to the initiation and regulation of the adaptive immune response during infection. Modulation of DC function may therefore allow evasion of the immune system by pathogens. Significant depression of the host's systemic immune response to both concurrent infections and heterologous vaccines has been observed during malaria infection, but the mechanisms underlying this immune hyporesponsiveness are controversial.

Results: Here, we demonstrate that the blood stages of malaria infection induce a failure of DC function in vitro and in vivo, causing suboptimal activation of T cells involved in heterologous immune responses. This effect on T-cell activation can be transferred to uninfected recipients by DCs isolated from infected mice. Significantly, T cells activated by these DCs subsequently lack effector function, as demonstrated by a failure to migrate to lymphoid-organ follicles, resulting in an absence of B-cell responses to heterologous antigens. Fractionation studies show that hemozoin, rather than infected erythrocyte (red blood cell) membranes, reproduces the effect of intact infected red blood cells on DCs. Furthermore, hemozoin-containing DCs could be identified in T-cell areas of the spleen in vivo.

Conclusion: Plasmodium infection inhibits the induction of adaptive immunity to heterologous antigens by modulating DC function, providing a potential explanation for epidemiological studies linking endemic malaria with secondary infections and reduced vaccine efficacy.

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P. chabaudi infection causes reduced expansion of B cells and failure of CD4+ T-cell migration through modulation of DCs. (a) Uninfected (squares) or P. chabaudi-infected (circles) BALB/c mice received OVA-specific CD4+ T cells and HEL-specific B cells 12 days after infection and were immunized with OVA-HEL/LPS (filled symbols) 24 h later. Controls remained unimmunized (open symbols). Results shown are the absolute number of HEL-specific B cells in the spleen (left) and lymph nodes (LN, right) and represent the mean of 3 mice per group ±1 s.d. and are representative of 3 similar experiments (*p ≤ 0.05, #p ≤ 0.005 uninfected and immunized versus P. chabaudi-infected immunized). (b) Five days after immunization, spleens from the mice described in (a) were snap frozen and prepared for immunohistochemistry. Sections were stained using biotinylated-KJ1.26 followed by Streptavidin-AlexaFluor 647 to detect OVA-specific T cells (red) and B220-FITC to identify B-cell areas (green). Images shown are representative of 3 mice per group from 2 similar experiments. (c) Sections stained as in (b) were analyzed by laser-scanning cytometry. Results are expressed as mean proportion of OVA-specific T cells per unit area in the regions indicated. The number of OVA-specific T cells contained in identically sized regions of follicle and periarteriolar lymphoid sheath (PALS) was calculated and expressed as a proportion of total KJ1.26+ cells in the section to avoid bias due to the difference in expansion between uninfected and infected spleens. Results represent triplicate readings of 3 mice per group ±1 s.d. (*p ≤ 0.05 uninfected and immunized versus P. chabaudi-infected and immunized). (d) Bone-marrow-derived DCs were cultured with P. chabaudi pRBCs (circles) or RBCs (squares) for 18 h before pulsing with 5 mg/ml OVA (filled symbols). Controls remained unpulsed (open symbols). OVA-specific CD4+ T cells were then added at a ratio of 1:1 and cultured for 72 h in vitro. T cells were isolated, washed and transferred into uninfected recipients immunized 48 h before transfer to synchronize the immune response. Clonal expansion was then assessed as described above. Results show the mean proportion of CD4+KJ1.26+ T cells and represent the mean of 3 mice per group ±1 s.d. (*p ≤ 0.05, RBC-cultured, OVA-pulsed DCs versus pRBC-cultured, OVA-pulsed DC). (e) DCs were purified from spleens of uninfected or P. chabaudi-infected mice and pulsed with 5 mg/ml OVA for 2 h. Cells were then harvested, washed and 5 × 105 DCs transferred into uninfected BALB/c mice along with CFSE-labeled OVA-specific T cells. The level of CFSE in OVA-specific CD4+ cells was analyzed 5 days later, as described in Figure 8.
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Figure 9: P. chabaudi infection causes reduced expansion of B cells and failure of CD4+ T-cell migration through modulation of DCs. (a) Uninfected (squares) or P. chabaudi-infected (circles) BALB/c mice received OVA-specific CD4+ T cells and HEL-specific B cells 12 days after infection and were immunized with OVA-HEL/LPS (filled symbols) 24 h later. Controls remained unimmunized (open symbols). Results shown are the absolute number of HEL-specific B cells in the spleen (left) and lymph nodes (LN, right) and represent the mean of 3 mice per group ±1 s.d. and are representative of 3 similar experiments (*p ≤ 0.05, #p ≤ 0.005 uninfected and immunized versus P. chabaudi-infected immunized). (b) Five days after immunization, spleens from the mice described in (a) were snap frozen and prepared for immunohistochemistry. Sections were stained using biotinylated-KJ1.26 followed by Streptavidin-AlexaFluor 647 to detect OVA-specific T cells (red) and B220-FITC to identify B-cell areas (green). Images shown are representative of 3 mice per group from 2 similar experiments. (c) Sections stained as in (b) were analyzed by laser-scanning cytometry. Results are expressed as mean proportion of OVA-specific T cells per unit area in the regions indicated. The number of OVA-specific T cells contained in identically sized regions of follicle and periarteriolar lymphoid sheath (PALS) was calculated and expressed as a proportion of total KJ1.26+ cells in the section to avoid bias due to the difference in expansion between uninfected and infected spleens. Results represent triplicate readings of 3 mice per group ±1 s.d. (*p ≤ 0.05 uninfected and immunized versus P. chabaudi-infected and immunized). (d) Bone-marrow-derived DCs were cultured with P. chabaudi pRBCs (circles) or RBCs (squares) for 18 h before pulsing with 5 mg/ml OVA (filled symbols). Controls remained unpulsed (open symbols). OVA-specific CD4+ T cells were then added at a ratio of 1:1 and cultured for 72 h in vitro. T cells were isolated, washed and transferred into uninfected recipients immunized 48 h before transfer to synchronize the immune response. Clonal expansion was then assessed as described above. Results show the mean proportion of CD4+KJ1.26+ T cells and represent the mean of 3 mice per group ±1 s.d. (*p ≤ 0.05, RBC-cultured, OVA-pulsed DCs versus pRBC-cultured, OVA-pulsed DC). (e) DCs were purified from spleens of uninfected or P. chabaudi-infected mice and pulsed with 5 mg/ml OVA for 2 h. Cells were then harvested, washed and 5 × 105 DCs transferred into uninfected BALB/c mice along with CFSE-labeled OVA-specific T cells. The level of CFSE in OVA-specific CD4+ cells was analyzed 5 days later, as described in Figure 8.

Mentions: One of the most significant components of CD4+ T-cell effector function is migration into primary lymphoid follicles to interact with, and provide help for, antigen-specific B cells [50]. To track the effect of malaria infection on these populations, we transferred B-cell-receptor transgenic B cells specific for hen egg-white lysozyme (HEL) taken from the MD4 transgenic mouse, together with the OVA-specific DO11.10 T cells and immunized with OVA coupled to HEL [51]. B-cell expansion in uninfected animals peaked 5 days after immunization (Figure 9a). Expansion of HEL-specific B cells was almost completely ablated in P. chabaudi-infected animals immunized with OVA-HEL/LPS (Figure 9a), however, suggesting a defect in B-cell activation and/or T-cell help in infected mice.


Suppression of adaptive immunity to heterologous antigens during Plasmodium infection through hemozoin-induced failure of dendritic cell function.

Millington OR, Di Lorenzo C, Phillips RS, Garside P, Brewer JM - J. Biol. (2006)

P. chabaudi infection causes reduced expansion of B cells and failure of CD4+ T-cell migration through modulation of DCs. (a) Uninfected (squares) or P. chabaudi-infected (circles) BALB/c mice received OVA-specific CD4+ T cells and HEL-specific B cells 12 days after infection and were immunized with OVA-HEL/LPS (filled symbols) 24 h later. Controls remained unimmunized (open symbols). Results shown are the absolute number of HEL-specific B cells in the spleen (left) and lymph nodes (LN, right) and represent the mean of 3 mice per group ±1 s.d. and are representative of 3 similar experiments (*p ≤ 0.05, #p ≤ 0.005 uninfected and immunized versus P. chabaudi-infected immunized). (b) Five days after immunization, spleens from the mice described in (a) were snap frozen and prepared for immunohistochemistry. Sections were stained using biotinylated-KJ1.26 followed by Streptavidin-AlexaFluor 647 to detect OVA-specific T cells (red) and B220-FITC to identify B-cell areas (green). Images shown are representative of 3 mice per group from 2 similar experiments. (c) Sections stained as in (b) were analyzed by laser-scanning cytometry. Results are expressed as mean proportion of OVA-specific T cells per unit area in the regions indicated. The number of OVA-specific T cells contained in identically sized regions of follicle and periarteriolar lymphoid sheath (PALS) was calculated and expressed as a proportion of total KJ1.26+ cells in the section to avoid bias due to the difference in expansion between uninfected and infected spleens. Results represent triplicate readings of 3 mice per group ±1 s.d. (*p ≤ 0.05 uninfected and immunized versus P. chabaudi-infected and immunized). (d) Bone-marrow-derived DCs were cultured with P. chabaudi pRBCs (circles) or RBCs (squares) for 18 h before pulsing with 5 mg/ml OVA (filled symbols). Controls remained unpulsed (open symbols). OVA-specific CD4+ T cells were then added at a ratio of 1:1 and cultured for 72 h in vitro. T cells were isolated, washed and transferred into uninfected recipients immunized 48 h before transfer to synchronize the immune response. Clonal expansion was then assessed as described above. Results show the mean proportion of CD4+KJ1.26+ T cells and represent the mean of 3 mice per group ±1 s.d. (*p ≤ 0.05, RBC-cultured, OVA-pulsed DCs versus pRBC-cultured, OVA-pulsed DC). (e) DCs were purified from spleens of uninfected or P. chabaudi-infected mice and pulsed with 5 mg/ml OVA for 2 h. Cells were then harvested, washed and 5 × 105 DCs transferred into uninfected BALB/c mice along with CFSE-labeled OVA-specific T cells. The level of CFSE in OVA-specific CD4+ cells was analyzed 5 days later, as described in Figure 8.
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Figure 9: P. chabaudi infection causes reduced expansion of B cells and failure of CD4+ T-cell migration through modulation of DCs. (a) Uninfected (squares) or P. chabaudi-infected (circles) BALB/c mice received OVA-specific CD4+ T cells and HEL-specific B cells 12 days after infection and were immunized with OVA-HEL/LPS (filled symbols) 24 h later. Controls remained unimmunized (open symbols). Results shown are the absolute number of HEL-specific B cells in the spleen (left) and lymph nodes (LN, right) and represent the mean of 3 mice per group ±1 s.d. and are representative of 3 similar experiments (*p ≤ 0.05, #p ≤ 0.005 uninfected and immunized versus P. chabaudi-infected immunized). (b) Five days after immunization, spleens from the mice described in (a) were snap frozen and prepared for immunohistochemistry. Sections were stained using biotinylated-KJ1.26 followed by Streptavidin-AlexaFluor 647 to detect OVA-specific T cells (red) and B220-FITC to identify B-cell areas (green). Images shown are representative of 3 mice per group from 2 similar experiments. (c) Sections stained as in (b) were analyzed by laser-scanning cytometry. Results are expressed as mean proportion of OVA-specific T cells per unit area in the regions indicated. The number of OVA-specific T cells contained in identically sized regions of follicle and periarteriolar lymphoid sheath (PALS) was calculated and expressed as a proportion of total KJ1.26+ cells in the section to avoid bias due to the difference in expansion between uninfected and infected spleens. Results represent triplicate readings of 3 mice per group ±1 s.d. (*p ≤ 0.05 uninfected and immunized versus P. chabaudi-infected and immunized). (d) Bone-marrow-derived DCs were cultured with P. chabaudi pRBCs (circles) or RBCs (squares) for 18 h before pulsing with 5 mg/ml OVA (filled symbols). Controls remained unpulsed (open symbols). OVA-specific CD4+ T cells were then added at a ratio of 1:1 and cultured for 72 h in vitro. T cells were isolated, washed and transferred into uninfected recipients immunized 48 h before transfer to synchronize the immune response. Clonal expansion was then assessed as described above. Results show the mean proportion of CD4+KJ1.26+ T cells and represent the mean of 3 mice per group ±1 s.d. (*p ≤ 0.05, RBC-cultured, OVA-pulsed DCs versus pRBC-cultured, OVA-pulsed DC). (e) DCs were purified from spleens of uninfected or P. chabaudi-infected mice and pulsed with 5 mg/ml OVA for 2 h. Cells were then harvested, washed and 5 × 105 DCs transferred into uninfected BALB/c mice along with CFSE-labeled OVA-specific T cells. The level of CFSE in OVA-specific CD4+ cells was analyzed 5 days later, as described in Figure 8.
Mentions: One of the most significant components of CD4+ T-cell effector function is migration into primary lymphoid follicles to interact with, and provide help for, antigen-specific B cells [50]. To track the effect of malaria infection on these populations, we transferred B-cell-receptor transgenic B cells specific for hen egg-white lysozyme (HEL) taken from the MD4 transgenic mouse, together with the OVA-specific DO11.10 T cells and immunized with OVA coupled to HEL [51]. B-cell expansion in uninfected animals peaked 5 days after immunization (Figure 9a). Expansion of HEL-specific B cells was almost completely ablated in P. chabaudi-infected animals immunized with OVA-HEL/LPS (Figure 9a), however, suggesting a defect in B-cell activation and/or T-cell help in infected mice.

Bottom Line: This effect on T-cell activation can be transferred to uninfected recipients by DCs isolated from infected mice.Significantly, T cells activated by these DCs subsequently lack effector function, as demonstrated by a failure to migrate to lymphoid-organ follicles, resulting in an absence of B-cell responses to heterologous antigens.Fractionation studies show that hemozoin, rather than infected erythrocyte (red blood cell) membranes, reproduces the effect of intact infected red blood cells on DCs.

View Article: PubMed Central - HTML - PubMed

Affiliation: Division of Immunology, Infection and Inflammation, University of Glasgow, Glasgow G11 6NT, UK. owain.millington@strath.ac.uk

ABSTRACT

Background: Dendritic cells (DCs) are central to the initiation and regulation of the adaptive immune response during infection. Modulation of DC function may therefore allow evasion of the immune system by pathogens. Significant depression of the host's systemic immune response to both concurrent infections and heterologous vaccines has been observed during malaria infection, but the mechanisms underlying this immune hyporesponsiveness are controversial.

Results: Here, we demonstrate that the blood stages of malaria infection induce a failure of DC function in vitro and in vivo, causing suboptimal activation of T cells involved in heterologous immune responses. This effect on T-cell activation can be transferred to uninfected recipients by DCs isolated from infected mice. Significantly, T cells activated by these DCs subsequently lack effector function, as demonstrated by a failure to migrate to lymphoid-organ follicles, resulting in an absence of B-cell responses to heterologous antigens. Fractionation studies show that hemozoin, rather than infected erythrocyte (red blood cell) membranes, reproduces the effect of intact infected red blood cells on DCs. Furthermore, hemozoin-containing DCs could be identified in T-cell areas of the spleen in vivo.

Conclusion: Plasmodium infection inhibits the induction of adaptive immunity to heterologous antigens by modulating DC function, providing a potential explanation for epidemiological studies linking endemic malaria with secondary infections and reduced vaccine efficacy.

Show MeSH
Related in: MedlinePlus