Effect of progranulin on expression of interleukin-10 and polarization of pulmonary macrophages through the regulation of regulatory T cells

Abstract:

Objective：To study the effect of progranulin（PGRN） on the expression of interleukin（IL）-10 and the polarization of pulmonary macrophages through the regulation of regulatory T cells（Tregs） in mouse model with acute lung injury（ALI）. Methods：The C57BL/6 mice were randomly divided into the normal control group（Control group），the lipopolysaccharides（LPS） group and the LPS+PGRN treatment group（LPS+PGRN group）. The ALI mouse model was induced by LPS（2.5 mg/kg） via intratracheal instillation. The LPS+PGRN group was treated with 0.1 mg/kg PGRN after half an hour of LPS instillation. The mice were anesthetized with 3% chloral hydrate at 24h after LPS instillation，lung tissues and heparin anticoagulant blood were taken. The severity of lung injury was evaluated by histopathology with hematoxylin and eosin staining. The Tregs in peripheral blood was detected by flow cytometry. The expression of IL-6，tumor necrosis factor（TNF）-α and IL-10 in plasma were tested by enzyme linked immunosorbent assay. The phenotype of macrophages in lung tissue was detected by immunofluorescence. Results：The ratio of Tregs in peripheral blood，the expression of IL-6，TNF-α，and IL-10 in plasma，and the proportion of M1 and M2 macrophages in the lung tissue between different groups had statistically significant differences（F=69.340，P=0.000；F=73.100，P=0.000；F=17.800，P=0.000；F=11.780，P=0.003；F=67.560，P=0.000；F=197.100，P=0.000）. After PGRN treatment，the lung injury of ALI mouse model was significantly reduced and the proportion of Tregs in peripheral blood was higher[LPS：（4.714±0.265）%，LPS+PGRN：（8.930±0.255）%，P=0.000]. The expression of proinflammatory cytokines IL-6[LPS：（3 021.000±294.900） pg/mL，LPS+PGRN：（276.700±148.000） pg/mL，P=0.000] and TNF-α[LPS：（90.980±10.240） pg/mL，LPS+PGRN：（20.410±9.190） pg/mL，P=0.002] was significantly decreased. The expression of anti-inflammatory cytokine IL-10 in plasma significantly was increased[LPS：（296.400±44.280） pg/mL，LPS+PGRN：（2551.000±655.100） pg/mL，P=0.014]，and M1 lung macrophages was decreased[LPS：（17.870±1.890）%，LPS+PGRN：（4.436±0.248）%，P=0.000]，while M2 lung macrophages was increased[LPS：（2.284±0.444）%，LPS+PGRN：(11.920±0.458）%，P=0.000]. Conclusion：PGRN can increase the expression of IL-10 and M2 lung macrophages through the regulation of Tregs in ALI mouse model，so as to influence the polarization of lung macrophages.