Expression of IL-35 and its regulatory effects on Th9 cells in patients with type 1 diabetes mellitus / 中华微生物学和免疫学杂志

ABSTRACT

Objective:To investigate the changes in IL-35 expression in patients with type 1 diabetes mellitus (T1DM) and to analyze the role of IL-35 in regulating Th9 cells.Methods:Thirty-one T1DM patients and 13 controls were enrolled. Plasma and peripheral blood mononuclear cells (PBMCs) were isolated. The levels of IL-35 and IL-9 in plasma were measured by ELISA. The expression of IL-35 subunits, EBI3 and IL-12p35, as well as Th9 transcription factor PU.1 at mRNA level was detected by real-time PCR. The percentages of Th9 cells were measured by flow cytometry. Changes in cell proliferation, the percentage of Th9 cells, PU.1 expression at mRNA level and IL-9 secretion were detected after stimulating PBMCs from T1DM patients and controls with recombinant human IL-35. CD4 + CCR4 -CCR6 -CXCR3 - cells and CD8 + T cells were isolated from PBMCs of 11 T1DM patients. CD4 + CCR4 -CCR6 -CXCR3 - cells were first stimulated with recombinant human IL-35 and then co-cultured with CD8 + T cells. IFN-γ and TNF-α in the culture supernatants were measured by ELISA. Perforin and granzyme B secretion was measured by enzyme-linked immunospot assay. Student′s t-test, paired t-test or LSD- t test was used for statistical analysis. Results:Plasma IL-35 level was lower in T1DM patients than in controls [(67.13±9.94) pg/ml vs (97.77±23.61) pg/ml, P<0.000 1]. Compared with controls, T1DM patients had decreased expression of EBI3 and IL-12p35 at mRNA level in PBMCs ( P<0.000 1). The percentage of Th9 cells, PU.1 expression at mRNA level and plasma IL-9 level were increased in T1DM patients as compared with those in controls [(3.47±0.99)% vs (2.76±0.75)%, P=0.029; P<0.000 1; (99.08±11.85) pg/ml vs (86.38±12.72) pg/ml, P=0.002 8]. IL-35 had no significant influence on the proliferation of PBMCs from both T1DM patients and controls ( P>0.05). The percentage of Th9 cells and PU.1 expression at mRNA level in PBMCs from T1DM patients were down-regulated in response to IL-35 stimulation ( P<0.01), while no significant difference was observed in the control group ( P>0.05). IL-9 secretion by PBMCs was down-regulated in response to IL-35 stimulation in both T1DM and control groups ( P<0.01). CD4 + CCR4 -CCR6 -CXCR3 - cells promoted the secretion of IFN-γ, TNF-α, perforin and granzyme B by CD8 + T cells from T1DM patients ( P<0.05), but the effects could be inhibited by IL-35 ( P<0.05). Conclusions:Decreased IL-35 in T1DM patients could not exert effective immunosuppressive activity, leading to the enhancement of Th9 cell activity and inflammatory injury.