JAK/STAT5 signaling pathway inhibitor ruxolitinib reduces airway inflammation of neutrophilic asthma in mice model.

OBJECTIVE: The aim of this study was to explore the role of JAK/STAT signaling pathway inhibitor Ruxolitinib in neutrophilic airway inflammation and its possible immunological mechanism.

MATERIALS AND METHODS: A total of 60 female C57BL/6 mice were randomly divided into neutrophilic asthma (NA) group, Ruxolitinib-treated (Ruxo) group and control (Con) group. Mice in NA and Ruxo groups were sensitized with ovalbumin (OVA) and excited to establish mice models of asthma. Bronchoalveolar lavage fluid (BALF) was collected at 24 h after the last atomization, and the total number of karyocyte and the percentages of sorted cells were detected. The activity of interleukin-17 (IL-17) in BALF was detected by enzyme-linked immunosorbent assay (ELISA). Lung tissue was separated and subjected to hematoxylin-eosin (HE) staining, and the pathological changes of lung tissue were observed under an optical microscope. The proportion of T helper 17 (Th17) cells in the lung was detected by flow cytometry (FCM). After successful modeling of NA mice, immunomagnetic bead purified mouse splenic cluster of differentiation 4+(CD4+) T was treated with IL-7 and Ruxolitinib, and the proportion of differentiated Th17 cells to CD4+ T cells and Ki-67, B-cell lymphoma 2 (Bcl-2) and activated Caspase3 expressions in Th17 cells were detected via FCM.

RESULTS: Compared with those in NA group, the number of karyocytes and the percentages of neutrophils (NEU) and eosinophils (EOS) in BALF in Ruxo group were significantly reduced. The pathological changes of lung tissue in Ruxo group were overtly less than those in NA group. In comparison with NA group, Ruxo group had decreased IL-17A level in BALF and reduced proportion of Th17 cells in lung tissue. In in vitro experiment, compared with those in Con group, decreased percentages of Ki-67 and Bcl-2 proteins and increased percentage of Caspase3 in Th17 cells were found in Ruxo group.

CONCLUSIONS: Ruxolitinib may suppress the survival of Th17 cells by inhibiting the JAK/STAT5 signaling pathway and regulate the anti-apoptosis proteins Bcl-2 and Caspase3, thus promoting the increase of Thl7 cells entering the apoptotic pathway and reducing airway inflammation in NA mice.