Profiling of human IL-22+ T cell clones from patients affected with Schistosoma mansoni: Insights into macrophage regulation and liver fibrosis

Abstract

Tissue damage in Schistosoma mansoni infection results from a granulomatous, T cell-mediated response to parasite eggs, leading to liver fibrosis and portal hypertension. This immune response, initially Th1-dominated, progressively shifts toward a Th2 profile, contributing to hepatic stellate cell (HSC) activation and fibrosis. However, the precise regulatory mechanisms remain unclear. In this study, we analyzed T cell responses to soluble egg antigens (SEA) in 121 T cell clones (Tcc) from S. mansoni-infected patients. All clones produced high levels of IL-13 upon anti-CD3 stimulation; a minority secreted IFN-γ (n = 33) or IL-10 (n = 38). Notably, 51 clones co-produced IL-22 and IL-13. To investigate IL-22's role, we examined IL-22 receptor (IL-22R) expression on human M0 and M2 macrophages. Both subsets expressed IL-22R, and its engagement triggered phosphorylation of p38, STAT3, and STAT5. IL-22 also downregulated IL-13-induced M2 markers (CD163, CD200R). Furthermore, IL-22 treatment of HSCs inhibited IL-13-driven collagen I/III production and cell proliferation. These results suggest that IL-22-producing T cells modulate Th2 macrophage polarization and directly suppress fibrogenesis in HSCs. IL-22 may thus act as a regulatory cytokine counteracting liver fibrosis during schistosomiasis.

Fig 1. Cells obtained from 8 different donors were collected, treated with SEA (10

μg/ml) for 5 days and proliferation analyzed by FACS, as described in Methods. The plots show the data obtained in the presence (SEA) and absence of antigen (CTR) in one representative experiment out of 8. In B the percentage of proliferating cells from each donor compared to non affected control (*p ≤ 0.05 as calculated by paired Student’s t test) is shown.

Fig 2. PBMC from 8 patients were co-cultured with or without SEA (10

μg/ml) and culture supernatants were collected at day 5. Cytokine content was measured by ELISA Data are expressed as mean pgs/100.000 cells ± SD of triplicates (*p ≤ 0.05 as calculated by paired Student’s t test).

Fig 3. A) T cell lines obtained from PBMC of Schistosoma patients treated with SEA (10 μg/ml), cloned by limiting dilution and analyzed by ELISA after 48h incubation with anti-CD3 Ab. Bars of the graph represent the number of pg/ml of IL-22, IFN, IL-10, IL4,IL-13,IL17 secreted by each clone obtained from 3 different donors. B) Euler diagram of cytokines expression of T cell clones obtained from 3 different donors.

Fig 4. M0 and M2 macrophages obtained from 3 healthy different donors were analyzed by Flow cytometry, as described in methods. Plot show the expression of IL-22 receptor and CD14 in M0 and M2 macrophages.

WB analysis was performed on protein lysates from M0 treated with 25ng/ml of IL-22 at different time point. The following antibodies were used: anti-phospho ERK1/2 (Thr202/Tyr202) cell signaling, anti-phospho P38 alpha (Thr 180,/Tyr 182), anti-phospho Stat3 (Tyr705), anti-phospho Stat5 (Tyr694), Gapdh was used as loading control. Numbers in bold represent fold increase of protein expression vs control. Figure represent one representative experiment of 3. Graphs represent the mean values of densitometric intensity (D.I.) of each band ± SD of DCs normalized to GAPDH(*p ≤ 0.05 **p ≤ 0.005, as calculated by paired Student’s t test).

Fig 5. A) M0 macrophages obtained from 3 different healthy donors were cultured 48h in the presence of IL-13 (20 ng/ml) with or without IL-22 (25 ng/ml) and analyzed by FACS, as described in Methods. The plots show the data of one representative experiment out of 3. B) Graphs show the percentage of cells expressing the indicated markers at 48h (*P < 0.05).

Fig 6. A) HSC were cultured for 24h presence or absence of IL-22 (25 ng/ml) and protein lysates were analyzed for Collagen I and III protein expression by western blots. Graph show the fold decrease of signals of a representative experiment out of 3. B) HSC were collected, treated with the cytokines, as described above, for 48h and cell proliferation was analyzed by FACS, as described in Methods. The plots show the data obtained in a representative experiment out of 3. C) HSC were cultured for 24h with IL-13 (20 ng/ml) in presence or absence of IL-22 (25 ng/ml) and protein lysates were analyzed for Collagen I and III protein expression by western blots. Graph show the fold decrease of signals of a representative experiment out of 3. D) HSC were collected, treated with the cytokines, as described above, for 48h and cell proliferation was analyzed by FACS, as described in Methods. The plots show the data obtained in a representative experiment out of 3.