Parasite-specific IL-17-type cytokine responses and soluble IL-17 receptor levels in Alveolar Echinococcosis patients

Abstract

Alveolar Echinococcosis (AE) caused by the cestode Echinococcus multilocularis, is a severe helminth infection of man, where unrestricted parasite growth will ultimately result in organ failure and fatality. The tissue-infiltrative growth of the larval metacestode and the limited efficacy of available drugs complicate successful intervention in AE; patients often need life-long medication, and if possible, surgical resection of affected tissues and organs. Resistance to AE has been reported, but the determinants which confer protection are not known. ln this study, we analyzed in patients at distinct stages of Alveolar Echirococcosis, that is cured, stable and progressive AE, as well as in infection-free controls, the cellular production and plasma levels of pro-inflammatory cytokines lL-17A, lL-17B, lL-17F and their soluble receptors lL-17RA (slL-17RA) and IL-17RB (sIL-17RB). Significantly elevated levels of IL-17B and slL-17RB were observed, whilst lL-17F and slL-17RA were reduced in patients with AE. Similarly, the cellular production of lL-17F and slL-L7RA in response to E. multilocularis antigens was low in AE patients, while levels of slL-17RB were highly enhanced. These observations suggest immune-modulating properties of E. multitocularis on lL-17 cytokine-mediated pro-inflammatory immune responses; this may facilitate the tissue infiltrative growth of the parasite and its persistence in the human host.

Figure 1

Plasma concentrations of interleukin (IL)-17B (part a) and soluble receptor IL-17RB (part b) in Alveolar Echinococcosis (AE) patients and in infection-free controls (CTRL). The patients were grouped according to their state of infection, that is, cured, stable, or progressive (Prog.) Alveolar Echinococcosis. The plasma concentrations are shown as the mean values in pg/mL with the 95% upper and lower confidence interval. The level of significance was adjusted by the Bonferroni-Holm method. Significant differences between the groups are indicated (*P < 0.05, **P < 0.01, and ***P < 0.001).

Figure 2

Plasma concentrations of interleukin (IL)-17A (part a) and IL-17F (part b) and of soluble IL-17RA (part c) in Alveolar Echinococcosis (AE) patients and infection-free controls (CTRL). Patients were grouped according to their state of infection, that is, cured, stable, or progressive (Prog.) Alveolar Echinococcosis. The plasma concentrations are shown as the mean values in pg/ml with the 95% upper and lower confidence interval. The level of significance was adjusted by the Bonferroni-Holm method. Significant differences between the groups are indicated (*P < 0.05, **P < 0.01, and ***P < 0.001).

Figure 3

Echinococcus multilocularis antigen induced cellular production of soluble interleukin-17 receptor A (sIL-17RA) by peripheral blood mononuclear cells (PBMCs) from Alveolar Echinococcosis (AE) patients and infection-free controls (CTRL). Patients were grouped according to their state of infection, that is, cured, stable, or progressive (Prog.) Alveolar Echinococcosis. PBMCs from patients and controls were stimulated with E. multilocularis vesicle extract (EmV) for 24 (part a) and 48 hours (part b) or left without stimulation. Cytokine concentrations in cell culture supernatant were quantified by specific ELISA. The EmAg-induced cytokine production (Netto Prod.) was calculated by subtracting the cytokine production in not stimulated PBMC cultures from EmV-stimulated cytokine production. The cytokine production is shown as mean values in pg/mL with the 95% upper and lower confidence interval. The level of significance was adjusted by the Bonferroni-Holm method. The significant differences between groups are indicated (*P < 0.05, **P < 0.01, ***P < 0.001).

Figure 4

Echinococcus multilocularis antigen induced cellular production of soluble interleukin-17 receptor B (sIL-17RB) by PBMC from Alveolar Echinococcosis (AE) patients and infection-free controls (CTRL). Patients were grouped according to their state of infection, that is, cured, stable, or progressive (Prog.) Alveolar Echinococcosis. PBMCs from patients and controls were stimulated with Echinococcus multilocularis vesicle extract (EmV) (a) and single-cell extract (EmZ) (b) for 24 and 48 hours or left unstimulated. Cytokine concentrations in cell culture supernatant were determined by specific ELISA. The EmAg-induced cytokine production (Netto Prod.) was calculated by subtracting the cytokine production in not stimulated PBMC (Baseline) cultures from EmV-stimulated cytokine production (Brutto production). The cytokine production is shown as mean values in pg/mL with the 95% upper and lower confidence interval. The level of significance was adjusted by the Bonferroni-Holm method. The significant differences between groups are indicated (*P < 0.05, **P < 0.01, and ***P < 0.001).

Figure 5

Echinococcus multilocularis antigen- (EmAg-) induced cellular production of interleukin-17F (IL-17F) by PBMC from Alveolar Echinococcosis (AE) patients and infection-free controls (CTRL). Patients were grouped according to their state of infection, that is, cured, stable, or progressive (Prog.) Alveolar Echinococcosis. PBMC from patients and controls were stimulated with E. multilocularis vesicle extract (EmV) for 24 (part a) and 48 hours (part b) or left unstimulated. Cytokine concentrations in cell culture supernatant were determined by specific ELISA. The EmAg-induced cytokine production (Netto Prod.) was calculated by subtracting the cytokine production in not stimulated PBMC cultures (baseline) from EmV-stimulated cytokine production (Brutto production). The cytokine production is shown as mean values in pg/mL with the 95% upper and lower confidence interval. The level of significance was adjusted by the Bonferroni-Holm method. The significant differences between groups are indicated (*P < 0.05, **P < 0.01, and ***P < 0.001).