Journal Article

Repression of JAK2-STAT1 and PD-L1 by CEP-33779 ameliorates the LPS-induced decline in phagocytic activity of alveolar macrophages and mitigates lung injury in mice

Wang, Hong-Yan, Tu, Yong-Sheng, Wang, Yu-Han, Li, A-Guo

2024

Overview

The role of the JAK2-STAT1/PD-L1 pathway in the phagocytic activity of alveolar macrophages (AMs) during LPS-induced acute lung injury in mice remains poorly understood. This study aims to explore whether the JAK2-STAT1/PD-L1 pathway is upregulated on AMs in LPS-induced mice acute lung injury and to further explore the impact of the JAK2-specific inhibitor CEP-33779 on the LPS-induced impairment of AMs phagocytic activity and lung injury. ALI was induced in mice via intratracheal administration of LPS, followed by intragastric administration of JAK2 inhibitor CEP-33779 suspension. Immunohistochemistry was conducted to assess PD-L1 expression in lung tissue, as well as p-JAK2, p-STAT1, and PD-L1 expression on AMs in bronchoalveolar lavage fluid (BALF) using immunofluorescence. Levels of TNF-α and IL-6, as well as protein concentration in BALF, were measured using enzyme-linked immunosorbent assay and Bicinchoninic acid assays, respectively. Hematoxylin-eosin staining and lung injury score were employed to evaluate pathological changes in mouse lungs. Total cell count in BALF was determined using a cell counter. Furthermore, western blot and immunofluorescence was conducted to assess the effect of JAK2 and STAT1 inhibitor on JAK2-STAT1 pathway activation and PD-L1 expression, while confocal microscopy with latex beads rabbit IgG FITC complex was used to observe MH-S cells phagocytic ability. The study revealed that LPS stimulation triggered the activation of the JAK2-STAT1 pathway and an upregulation of PD-L1 on AMs in both LPS-induced acute lung injury mice and MH-S cell lines. Moreover, treatment with the JAK2 and STAT1 inhibitor effectively reduced the activation of JAK2-STAT1 signaling, downregulated PD-L1 expression on AMs in BALF from LPS-induced ALI mice and LPS-stimulated MH-S cells, and significantly improved the LPS-induced reduction in phagocytic activity in MH-S cells. Most notably, CEP-33779 treatment significantly mitigated the pulmonary inflammatory response and lung injury in mice with LPS-induced ALI. Collectively, these findings imply that the JAK2-STAT1 pathway plays a role in the upregulation of PD-L1, which in turn is associated with the diminished phagocytic activity in LPS-induced AMs as well as lung injury. Furthermore, our study highlights that CEP-33779 treatment can effectively improve the reduced phagocytic activity of AMs and relieve lung injury induced by LPS through suppression of the JAK2-STAT1/PD-L1 pathway.

• Publisher: Frontiers Media SA,Frontiers Media S.A
• Subject: acute lung injury / Acute Lung Injury - chemically induced / Acute Lung Injury - immunology / Acute Lung Injury - metabolism / alveolar macrophage / Alveoli / Animals / Antibodies / B7-H1 Antigen - metabolism / Bacterial infections / Bronchus / Cell lines / CEP-33779 / Confocal microscopy / Cytokines / Disease Models, Animal / Edema / Enzyme-linked immunosorbent assay / Immunofluorescence / Immunoglobulin G / Immunohistochemistry / Immunology / Inflammation / Janus kinase 2 / Janus Kinase 2 - metabolism / Kinases / Latex beads / Lavage / Lipopolysaccharides / Lungs / Macrophages / Macrophages, Alveolar - drug effects / Macrophages, Alveolar - immunology / Macrophages, Alveolar - metabolism / Male / Mice / Mice, Inbred C57BL / Pathogens / PD-L1 / PD-L1 protein / Phagocytes / phagocytosis / Phagocytosis - drug effects / Sepsis / Signal Transduction / Stat1 protein / STAT1 Transcription Factor - metabolism / T cell receptors / Trachea / Tumor necrosis factor-α / Up-regulation