ILC2 regulates hyperoxia-induced lung injury via an enhanced Th17 cell response in the BPD mouse model.

BACKGROUD: Recent research has focused on the role of immune cells and immune responses in the pathogenesis of bronchopulmonary dysplasia (BPD), but the exact mechanisms have not yet been elucidated. Previously, the key roles of type 2 innate lymphoid cells (ILC2) in the lung immune network of BPD were explored. Here, we investigated the role Th17 cell response in hyperoxia-induced lung injury of BPD, as well as the relationship between ILC2 and Th17 cell response. METHODS: A hyperoxia-induced BPD mouse model was constructed and the pathologic changes of lung tissues were evaluated by Hematoxylin-Eosin staining. Flow cytometry analysis was conducted to determine the levels of Th17 cell, ILC2 and IL-6+ILC2. The expression levels of IL-6, IL-17 A, IL-17 F, and IL-22 in the blood serum and lung tissues of BPD mice were measured by ELISA. To further confirm the relationship between ILC2 and Th17 cell differentiation, ILC2 depletion was performed in BPD mice. Furthermore, we used immunomagnetic beads to enrich ILC2 and then flow-sorted mouse lung CD45+Lin-CD90.2+Sca-1+ILC2. The sorted ILC2s were injected into BPD mice via tail vein. Following ILC2 adoptive transfusion, the changes of Th17 cell response and lung injury were detected in BPD mice. RESULTS: The expression levels of Th17 cells and Th17 cell-related cytokines, including IL-17 A, IL-17 F, and IL-22, were significantly increased in BPD mice. Concurrently, there was a significant increase in the amount of ILC2 and IL-6+ILC2 during hyperoxia-induced lung injury, which was consistent with the trend for Th17 cell response. Compared to the control BPD group, ILC2 depletion was found to partially abolish the Th17 cell response and had protective effects against lung injury after hyperoxia. Furthermore, the adoptive transfer of ILC2 enhanced the Th17 cell response and aggravated lung injury in BPD mice. CONCLUSIONS: This study found that ILC2 regulates hyperoxia-induced lung injury by targeting the Th17 cell response in BPD, which shows a novel strategy for BPD immunotherapy.

Crosstalk between ILC2s and Th2 CD4+ T Cells in Lung Disease.

Cytokine secretion, such as interleukin-4 (IL-4), IL-5, IL-9, IL-13, and amphiregulin (Areg), by type 2 innate lymphoid cells (ILC2s) is indispensable for homeostasis, remodeling/repairing tissue structure, inflammation, and tumor immunity. Often viewed as the innate cell surrogate of T helper type 2 (Th2) cells, ILC2s not only secrete the same type 2 cytokines, but are also inextricably related to CD4+T cells in terms of cell origin and regulatory factors, bridging between innate and adaptive immunity. ILC2s interact with CD4+T cells to play a leading role in a variety of diseases through secretory factors. Here, we review the latest progress on ILC2s and CD4+T cells in the lung, the close relationship between the two, and their relevance in the lung disease and immunity. This literature review aids future research in pulmonary type 2 immune diseases and guides innovative treatment approaches for these diseases.

Dynamic Changes of NCR- Type 3 Innate Lymphoid Cells and Their Role in Mice with Bronchopulmonary Dysplasia.

Inflammation is one of the important pathogenesis of bronchopulmonary dysplasia (BPD). Type 3 innate lymphoid cells (ILC3) play a role in a variety of inflammatory lung diseases. In this study, we established the BPD model by injecting lipopolysaccharide into the amniotic cavity of pregnant mice. Here, we investigated the dynamic changes of ILC3 and NKP46- ILC3 population in lung tissues of mice from BPD and the control groups. Results showed that the proportion of ILC3 and NKP46-ILC3 in the BPD group was higher than those of the control group. In addition, the cytokines interleukin-17 (IL-17) and interleukin-22 (IL-22) secreted by ILC3 in this model had also changed that their expression was significantly increased compared with that of the control group. Flow cytometry demonstrated that ILC3 were a rapid source of IL-17. In the anti-CD90 knockdown experiment, we confirmed the alleviation of BPD inflammation in the absence of ILC3. In addition, we injected mice with anti-IL-17 neutralizing antibody, and the results showed that IL-17 could aggravate BPD inflammation. Taken together, ILC3 may play a pro-inflammatory role in BPD by secreting IL-17.

A crosstalk between type 2 innate lymphoid cells and alternative macrophages in lung development and lung diseases (Review).

Type 2 innate lymphoid cells (ILC2s) are important innate immune cells that are involved in type 2 inflammation, in both mice and humans. ILC2s are stimulated by factors, including interleukin (IL)­33 and IL­25, and activated ILC2s secrete several cytokines that mediate type 2 immunity by inducing profound changes in physiology, including activation of alternative (M2) macrophages. M2 macrophages possess immune modulatory, phagocytic, tissue repair and remodeling properties, and can regulate ILC2s under infection. The present review summarizes the role of ILC2s as innate cells and M2 macrophages as anti­inflammatory cells, and discusses current literature on their important biological significance. The present review also highlights how the crosstalk between ILC2s and M2 macrophages contributes to lung development, induces pulmonary parasitic expulsion, exacerbates pulmonary viral and fungal infections and allergic airway diseases, and promotes the development of lung diseases, such as pulmonary fibrosis, chronic obstructive pulmonary disease and carcinoma of the lungs.

[The number of ILC3 and their related cytokines IL-17 and IL-22 increase in lungs of mice with bronchopulmonary dysplasia].

Objective To investigate dynamic changes of type 3 innate lymphoid cells (ILC3) in lungs of mice with bronchopulmonary dysplasia (BPD). Methods Forty newborn C57BL/6 mice were randomized into air group and the hyperoxia group, 20 mice in each group. C57BL/6 newborn mice were delivered by caesarean section on the 19th day of pregnancy and exposed to 850 mL/L O2 for replication of the BPD model. Five mice in each group were sacrificed 1 day, 3, 7, 14 days after they were born for procurement of fresh lung tissues. HE staining was used to observe the pathological changes of lung tissues. ELISA was used to detect the protein content of downstream cytokines interleukin-17 (IL-17), IL-22 and granulocyte-macrophage colony stimulating factor (GM-CSF) in lung homogenate. Flow cytometry was used for measuring the proportion of ILC3 in lymphocytes as well as the proportions of IL-17+ ILC3 and IL-22+ ILC3 in the lung. Results The proportion of ILC3 in lung tissues reached the peak on the 7th day after birth. In contrast with the air group, the proportion of ILC3 in the hyperoxia group was significantly elevated at the same time points. The protein content of IL-17 and IL-22 in the hyperoxia group went up significantly in comparison with those in the air group at the same time points, while the GM-CSF content in the hyperoxia group showed no significant changes. The proportions of IL-17+ILC3 and IL-22+ILC3 in the hyperoxia group significantly increased as compared with those in the air group at the same time points. Conclusion The secretion of IL-17 and IL-22 derived from ILC3 is associated with BPD.

Tissue-Resident Type 2 Innate Lymphoid Cells Arrest Alveolarization in Bronchopulmonary Dysplasia.

Bronchopulmonary dysplasia (BPD) is a severe complication of the respiratory system associated with preterm birth. Type 2 innate lymphoid cells (ILC2s) play a major role in tissue homeostasis, inflammation, and wound healing. However, the role in BPD remains unclear. The present study showed that ILC2s, interleukin-4 (IL-4), IL-13, and anti-inflammatory (M2) macrophages increased significantly in BPD mice as compared to the control mice. Administration with recombinant mouse IL-33 amplified the above phenomena and aggravated the alveolar structural disorder and functional injury in mice subjected to BPD, and the opposite was true with anti-ST2 antibody. In addition, the depletion of ILC2s in BPD mice with anti-CD90.2 antibody substantially abolished the destructive effect on BPD. In the treatment of BPD with dexamethasone, the number of ILC2s and M2 macrophages and levels of IL-4 and IL-13 decreased with remission as compared to the control group. This study identified a major destructive role of the ILC2s in BPD that could be attenuated as a therapeutic strategy.

Sumoylation of CCAAT-enhancer-binding protein α inhibits lung differentiation in Bronchopulmonary Dysplasia model rats.

Bronchopulmonary dysplasia (BPD) is a major cause of mortality and morbidity in premature infants, characterized by alveolar simplification, surfactant deficiency, and respiratory distress. In the present study, we have investigated the functional roles of sumoylated CCAAT/enhancer binding protein alpha (C/EBPα) in the BPD rat model. A significant increase in small ubiquitin-like modifier 1 (SUMO1) and sumoylated C/EBPα protein levels were observed in BPD rats, and the levels of the sumoylated C/EBPα were associated with the pulmonary surfactant proteins (SPs). In order to confirm the role of sumoylated C/EBPα in BPD rats, SUMO1 was knocked down by lentiviral transfection of neonatal rat lungs with SUMO1-RNAi-LV. We found that the expression of C/EBPα and surfactant proteins increased following SUMO1 knockdown. Furthermore, the relatively low decrease in the levels of C/EBPα sumoylation was correlated with reduced glycogen consumption. Besides, co-immunoprecipitation assays revealed that sumoylation is involved in the regulation of the interaction between C/EBPα and TGFß2 in the lung. In conclusion, our findings indicate that sumoylation may act as a negative regulator of the C/EBPα-mediated transactivation in BPD rats.