Acute lung injury (ALI) is a significant complication of sepsis, characterized by high morbidity, mortality, and poor prognosis. Neutrophils, as critical intrinsic immune cells in the lung, play a fundamental role in the development and progression of ALI. During ALI, neutrophils generate neutrophil extracellular traps (NETs), and excessive NETs can intensify inflammatory injury. Research indicates that Taohe Chengqi decoction (THCQD) can ameliorate sepsis-induced lung inflammation and modulate immune function. This study aimed to investigate the mechanisms by which THCQD improves ALI and its relationship with NETs in sepsis patients, seeking to provide novel perspectives and interventions for clinical treatment. The findings demonstrate that THCQD enhanced survival rates and reduced lung injury in the cecum ligation and puncture (CLP)-induced ALI mouse model. Furthermore, THCQD diminished neutrophil and macrophage infiltration, inflammatory responses, and the production of pro-inflammatory cytokines, including interleukin-1β (IL-1β), IL-6, and tumor necrosis factor α (TNF-α). Notably, subsequent experiments confirmed that THCQD inhibits NET formation both in vivo and in vitro. Moreover, THCQD significantly decreased the expression of peptidyl arginine deiminase 4 (PAD4) protein, and molecular docking predicted that certain active compounds in THCQD could bind tightly to PAD4. PAD4 overexpression partially reversed THCQD's inhibitory effects on PAD4. These findings strongly indicate that THCQD mitigates CLP-induced ALI by inhibiting PAD4-mediated NETs.
Extracellular Traps/immunology* ; Acute Lung Injury/immunology* ; Animals ; Sepsis/immunology* ; Drugs, Chinese Herbal/pharmacology* ; Mice ; Neutrophils/immunology* ; Male ; Protein-Arginine Deiminase Type 4/genetics* ; Mice, Inbred C57BL ; Humans ; Disease Models, Animal ; Cytokines/metabolism*

OBJECTIVES: To investigate the inhibitory effect of GSK484, a PAD4 inhibitor, on H3Cit expression following sepsis and its effects for improving sepsis-induced endothelial dysfunction. METHODS: Eighteen C57BL/6 mice were randomized into sham-operated group, sepsis model group and GSK484 treatment group (n=6), and in the latter two groups, models of sepsis were established by cecal ligation and puncture (CLP). The mice in GSK484 treatment group were given an intraperitoneal injection of GSK484 (4 mg/kg) on the second day following the surgery. Twenty-four hours after the injection, the mice were euthanized for measurement of serum levels of VEGF, ESM-1, IL-6 and IL-1β using ELISA. Lung tissue pathology was observed with HE staining, and pulmonary expressions of F-actin, VE-cadherin, ZO-1 and H3Cit proteins were detected using immunofluorescence staining and Western blotting. In primary cultured of mouse lung microvascular endothelial cells, the effect of stimulation with LPS (10 μg/mL) for 24 h on tube formation, proliferation, apoptosis and expressions of VEGF, ESM-1, IL-6 and IL-1β were assessed using CCK-8 assay, flow cytometry and ELISA. RESULTS: Compared to the sham-operated mice, the septic mice exhibited significant lung tissue pathologies characterized by vascular congestion, alveolar rupture, edema, and neutrophil infiltration. Serum levels of IL-6, IL-1β, VEGF, and ESM-1 were elevated, pulmonary expressions of F-actin, VE-cadherin, and ZO-1 were decreased, and H3Cit expression was increased significantly in the septic mice. GSK484 treatment effectively mitigated these changes in the septic mice. The LPS-stimulated endothelial cells showed increased productions of IL-6, IL-1β, VEGF and ESM-1, which were significantly reduced after treatment with 2.5 μmol/L GSK484. CONCLUSIONS GSK484 treatment effectively suppresses H3Cit expression in septic mice to ameliorate sepsis-induced endothelial dysfunction.
Animals ; Sepsis/drug therapy* ; Mice ; Mice, Inbred C57BL ; Lung Injury/drug therapy* ; Endothelial Cells/drug effects* ; Interleukin-6/metabolism* ; Protein-Arginine Deiminase Type 4/metabolism* ; Lung/metabolism* ; Vascular Endothelial Growth Factor A/metabolism* ; Interleukin-1beta/metabolism* ; Disease Models, Animal ; Cadherins/metabolism* ; Apoptosis/drug effects* ; Imidazoles ; Antigens, CD

OBJECTIVE: To investigate the expression of peptidylarginine deiminase 4 (PADI4) during the process of differentiation into granulocyte of NB4 cells induced by all-trans-retinoic acid (ATRA) and whether PADI4 is involved in the inflammatory cytokines expression. METHODS: Granulocyte differentiation model of NB4 cells induced by ATRA was established. The cell morphology changes were observed by Wright-Giemsa staining. The expression of cell differentiation marker CD11b was analyzed by flow cytometry. The mRNA and protein expression of PADI4 was detected by RT-PCR and Western blot, respectively. The expression of tumor necrosis factor (TNF) α and interleukin (IL) 1β was analyzed by ELISA, and also examined with the knockdown of PADI4 expression by siRNA. RESULTS: After NB4 cells induced by ATRA, the cytoplasm increased and the ratio of nuclear to cytoplasmic was reduced. Nuclear dented, and rod-shaped nucleus, lobulated phenomenon increased (P<0.05). Flow cytometry analysis results showed that the cell surface molecule CD11b expression increased (P<0.01). RT-PCR and Western blot showed the expression of PADI4 increased at both transcriptional and translational levels during the process of the differentiation. ELISA showed TNF-α and IL-1β secretion increased in differentiated macrophages, while they could be inhibited by PADI4-specific siRNA. CONCLUSION During the differentiation into granulocyte of NB4 cells induced by ATRA, PADI4 expression increased. Furthermore, PADI4 appeared to play a critical role in inflammatory cytokines secretion.
Cell Differentiation ; Cell Line, Tumor ; Cytokines/metabolism* ; Granulocytes ; Humans ; Leukemia, Promyelocytic, Acute ; Protein-Arginine Deiminase Type 4/metabolism* ; Tretinoin/pharmacology*