Interleukin-10 (IL-10) in experimental visceral leishmaniasis and IL-10 receptor blockade as immunotherapy - PubMed (original) (raw)

Interleukin-10 (IL-10) in experimental visceral leishmaniasis and IL-10 receptor blockade as immunotherapy

Henry W Murray et al. Infect Immun. 2002 Nov.

Abstract

Interleukin-10 (IL-10) is thought to promote intracellular infection, including human visceral leishmaniasis, by disabling Th1 cell-type responses and/or deactivating parasitized tissue macrophages. To develop a rationale for IL-10 inhibition as treatment in visceral infection, Th1 cytokine-driven responses were characterized in Leishmania donovani-infected BALB/c mice in which IL-10 was absent or overexpressed or its receptor (IL-10R) was blockaded. IL-10 knockout and normal mice treated prophylactically with anti-IL-10R demonstrated accelerated granuloma assembly and rapid parasite killing without untoward tissue inflammation; IL-12 and gamma interferon mRNA expression, inducible nitric oxide synthase reactivity, and responsiveness to antimony chemotherapy were also enhanced in knockout mice. In IL-10 transgenic mice, parasite replication was unrestrained, and except for antimony responsiveness, measured Th1 cell-dependent events were all initially impaired. Despite subsequent granuloma assembly, high-level infection persisted, and antimony-treated transgenic mice also relapsed. In normal mice with established infection, anti-IL-10R treatment was remarkably active, inducing near-cure by itself and synergism with antimony. IL-10's deactivating effects regulate outcome in experimental visceral leishmaniasis, and IL-10R blockade represents a potential immuno- and/or immunochemotherapeutic approach in this infection.

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Figures

FIG. 1.

FIG. 1.

Course of L. donovani liver infection in (A) normal BALB/c (open circles), IL-10 knockout (solid circles), control wild-type (open squares), and IL-10 transgenic (solid squares) mice and (B) in normal BALB/c mice injected intraperitoneally with control monoclonal antibody (open circles) or anti-IL-10R (solid circles) starting 1 day after infection and once weekly thereafter. Results in A and B are from two to three experiments and indicate mean ± standard error of the mean values for 6 to 15 mice per group at each time point. In A, P < 0.05 for knockout versus normal mice and for transgenic versus wild-type controls at weeks 3, 4, and 8. In B, P < 0.05 for control monoclonal antibody- versus anti-IL-10R-treated mice at all time points.

FIG. 2.

FIG. 2.

Liver granuloma assembly (A), maturation (B), and antileishmanial function (C) after L. donovani challenge in IL-10 knockout (solid circles) and IL-10 transgenic (solid squares) mice. Results for normal BALB/c and wild-type controls were similar and were pooled (open circles). Data are from two experiments and indicate mean ± standard error of the mean values for four to five mice per group at each time point.

FIG. 3.

FIG. 3.

Histologic reaction to L. donovani in the liver. (A and C) Normal BALB/c mice 2 weeks after infection show early granuloma formation with recruited lymphocytes and monocytes at fused parasitized Kupffer cells (arrows). (B, D, and E) In contrast, in 2-week-infected knockout mice, granulomas are fully developed (mature), parasite-free, and primarily composed of mononuclear phagocytes with a few recruited lymphocytes (E, arrows). (F) By week 8, the tissue reaction in knockout mice has largely involuted. Magnification: (A and B) 315×; (C to E) 500×; (F) 200×.

FIG. 4.

FIG. 4.

Histologic effects of early or late application of IL-10R blockade in livers of normal BALB/c mice. (A and B) Mice injected with control monoclonal antibody (A) or anti-IL-10R (B) 1 day after infection (day +1) and on day +7; livers were examined on day +14. Control monoclonal antibody-injected mice show developing granulomas containing numerous amastigotes; anti-IL-10R-treated mice demonstrate mature, parasite-free granulomas with few surrounding lymphocytes. (C and D) Mice injected once with control monoclonal antibody (C) or anti-IL-10R (D) 2 weeks after infection (day +14) and then examined on day +21. In D, anti-IL-10R treatment enhanced granuloma assembly and maturation. Magnification: (A and B) 500×; (C and D) 315×.

FIG. 5.

FIG. 5.

Histologic effects of sustained IL-10 in infected livers. (A, C, and E) Control wild-type mice show initial granuloma assembly at week 2 (A), full maturation at week 4 (C), and granuloma involution with resolution of infection at week 8 (E). (B, D, and F) IL-10 transgenic mice show poor cell recruitment, suppressed granuloma assembly, and heavily parasitized Kupffer cells at week 2 (B), emerging granulomas at week 4 (D), and mature granulomas at week 8 (F). Despite intact structure, week 8 granulomas are filled with amastigotes. Magnification: (A, B, and F) 500×; (C to E) 315×.

FIG. 6.

FIG. 6.

IL-12 p40 (A) and IFN-γ (B) mRNA expression 2 and 4 weeks after L. donovani infection in livers of normal BALB/c (□) and IL-10 knockout (▨) mice and wild-type (▪) and IL-10 transgenic (▤) mice. Reverse transcription-PCR results, normalized to the amount of β-actin mRNA in each lane, are mean values for three to four mice per group at each time point (standard error of the mean range, 3 to 21%). Results are expressed as increase over the mean amount of cytokine mRNA in livers of uninfected mice from the same group.

FIG. 7.

FIG. 7.

Immunocytochemical expression of inducible nitric oxide synthase at parasitized liver granulomas 2 weeks after L. donovani infection. (A) Normal BALB/c and (B) IL-10 knockout mice; (C) wild-type and (D) IL-10 transgenic mice. In D, arrows indicate reduced to nearly absent inducible nitric oxide synthase reaction product at parasitized foci in transgenic mice. Magnification: ×200.

FIG. 8.

FIG. 8.

Response to antimony treatment in IL-10 knockout (A) and transgenic (B) mice. (A) One week after infection (day +7), liver parasite burdens in normal BALB/c (655 ± 58 LDU, n = 6) and knockout mice (620 ± 43 LDU, n = 8) were similar and are indicated by intersection of the arrow-headed line with the vertical axis. Normal (open circles) and IL-10 knockout (solid circles) mice were injected once intraperitoneally on day +7 with the indicated suboptimal doses of antimony, and LDUs were measured on day +14. Day +14 results (two experiments, mean ± standard error of the mean values for seven to nine mice per group) above the horizontal line indicate parasite replication and below the line indicate parasite killing. (B) Wild-type (open squares) and IL-10 transgenic (solid squares) mice were injected once with optimal-dose antimony (500 mg/kg) on day +14 and then received no further treatment. Results indicate mean ± standard error of the mean values from two experiments for 6 to 10 mice at each time point. In A, P < 0.05 for treated knockout versus normal mice at all antimony doses. In B, P < 0.05 for transgenic versus wild-type controls at week 12.

FIG. 9.

FIG. 9.

Treatment effect of anti-IL-10R monoclonal antibody alone (A) or combined with antimony (B) in normal BALB/c mice. (A) Two weeks after infection, mice received no treatment (open squares) or injections of control monoclonal antibody (open circles) or anti-IL-10R monoclonal antibody (solid circles) on days +14 and +21. Solid square indicates mice injected only on day +14 with anti-IL-10R monoclonal antibody. (B) At 12 days after infection, mice received no treatment (group 1) or a single injection of control monoclonal antibody (group 2) or anti-IL-10R (group 3). Mice in each group were then not further treated (open bars) or on day +14 received antimony, 50 mg/kg (hatched bars). Solid bar indicates control group 1 mice injected on day +14 with optimal-dose antimony (500 mg/kg). LDUs were determined in untreated mice on day +14 and in all mice on day +21. Results in A and B are from two to three experiments and indicate mean ± standard error of the mean values for 6 to 11 mice at each time point. In A, P < 0.05 for day +21 and +28 for anti-IL-10R- versus control monoclonal antibody-treated mice. In B, P < 0.05 for anti-IL-10R- versus control monoclonal antibody-treated mice on day +21 without or with antimony treatment and for anti-IL-10R monoclonal antibody alone versus anti-IL-10R plus antimony on day +21.

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