ß-Nitrostyrene derivatives attenuate LPS-mediated acute lung injury via the inhibition of neutrophil-platelet interactions and NET release.

Acute lung injury (ALI) and the acute respiratory distress syndrome (ARDS) are high-mortality and life-threatening diseases that are associated with neutrophil activation and accumulation within lung tissue. Emerging evidence indicates that neutrophil-platelet aggregates (NPAs) at sites of injury increase acute inflammation and contribute to the development of ALI. Although numerous studies have increased our understanding of the pathophysiology of ALI, there is still a lack of innovative and useful treatments that reduce mortality, emphasizing that there is an urgent need for novel treatment strategies. In this study, a new series of small compounds of ß-nitrostyrene derivatives (BNSDs) were synthesized, and their anti-inflammatory bioactivities on neutrophils and platelets were evaluated. The new small compound C7 modulates neutrophil function by inhibiting superoxide generation and elastase release. Compound C7 elicits protective effects on LPS-induced paw edema and acute lung injury via the inhibition of neutrophil accumulation, proinflammatory mediator release, platelet aggregation, myeloperoxidase activity, and neutrophil extracellular trap (NET) release. NET formation was identified as the bridge for the critical interactions between neutrophils and platelets by confocal microscopy and flow cytometry. This research provides new insights for elucidating the complicated regulation of neutrophils and platelets in ALI and sheds further light on future drug development strategies for ALI/ARDS and acute inflammatory diseases.

Protective role of casuarinin from Melastoma malabathricum against a mouse model of 5-fluorouracil-induced intestinal mucositis: Impact on inflammation and gut microbiota dysbiosis.

BACKGROUND: 5-FU-induced intestinal mucositis (FUIIM) is a common gastrointestinal side effect of chemotherapy, leading to gastric pain in clinical cancer patients. In a previous study, we demonstrated that neutrophil elastase (NE) inhibitors could alleviate FUIIM and manipulate the homeostasis of the gut microbiota. The root of Melastoma malabathricum, also called Ye-Mu-Dan, has been used as a traditional Chinese medicine for gastrointestinal disease. Water extract of the roots of M. malabathricum exhibits an inhibitory effect on NE, with an IC50 value of 9.13 µg/ml. PURPOSE: In this study, we aimed to isolate an anti-NE compound from the root of M. malabathricum and to determine the protective effect of the bioactive component on a mouse model of FUIIM with respect to tissue damage, inflammation, intestinal barrier dysfunction, and gut microbiota dysbiosis. METHODS: A water extract of the roots of M. malabathricum was prepared and its major bioactive compound, was identified using bioactivity-guided fractionation. The effects of samples on the inhibition of NE activity were evaluated using enzymatic assays. To evaluate the effects of the bioactive compound in an FUIIM animal model, male C57BL/6 mice treated with or without casuarinin (50 and 100 mg/kg/day, p.o.), and then received of 5-fluorouracil (50 mg/kg/day) intraperitoneally for 5 days to induce FUIIM. Histopathological staining was used to monitor the tissue damage, proliferation of intestinal crypts, and expression of tight junction proteins. The inflammation score was estimated by determining the levels of oxidative stress, neutrophil-related proteases, and proinflammatory cytokines in tissue and serum. The ecology of the gut microbiota was evaluated using 16S rRNA gene sequencing. RESULTS: Casuarinin had the most potent and selective effect against NE, with an IC50 value of 2.79 ± 0.07 µM. Casuarinin (100 mg/kg/day, p.o.) significantly improved 5-FU-induced body weight loss together with food intake reduction, and it also significantly reversed villus atrophy, restored the proliferative activity of the intestinal crypts, and suppressed inflammation and intestinal barrier dysfunction in the mouse model of FUIIM. Casuarinin also reversed 5-FU-induced gut microbiota dysbiosis, particularly the abundance of Actinobacteria, Candidatus Arthromitus, and Lactobacillus murinus, and the Firmicutes-to-Bacteroidetes ratio. CONCLUSION: This study firstly showed that casuarinin isolated from the root part of M. malabathricum could be used as a NE inhibitor, whereas it could improve FUIIM by modulating inflammation, intestinal barrier dysfunction, and gut microbiota dysbiosis. In summary, exploring anti-NE natural product may provide a way to find candidate for improvement of FUIIM.

Neutrophil elastase inhibitor (MPH-966) improves intestinal mucosal damage and gut microbiota in a mouse model of 5-fluorouracil-induced intestinal mucositis.

BACKGROUND: 5-Fluorouracil (5-FU)-based chemotherapy is first-line chemotherapy for colorectal cancer. However, 5-FU-induced intestinal mucositis (FUIIM) is a common adverse effect that severely impairs drug tolerance and results in poor patient health. METHODS: Male C57BL/6 mice were given 5-FU (50 mg/kg/day, i.p.) and treated with MPH-966 (5 and 7.5 mg/kg/day, p.o.) for five days. The body weight loss and the amount of food intake, and histopathological findings were recorded and analyzed. In addition, the neutrophil infiltration, levels of neutrophil serine proteases and pro-inflammatory cytokines, and tight junction proteins expression in intestinal tissues were determined. The ecology of gut microbiota was performed through next-generation sequencing technologies. RESULTS: Neutrophil elastase (NE) overexpression is a key feature in FUIIM. This study showed that treatment with the specific NE inhibitor MPH-966 (7.5 mg/kg/day, p.o.) significantly reversed 5-FU-induced loss in body weight and food intake; reversed villous atrophy; significantly suppressed myeloperoxidase, NE, and proteinase 3 activity; and reduced pro-inflammatory cytokine expression in an FUIIM mouse model. In addition, MPH-966 prevented 5-FU-induced intestinal barrier dysfunction, as indicated by the modulated expression of the tight junction proteins zonula occludin-1 and occludin. MPH-966 also reversed 5-FU-induced changes in gut microbiota diversity and abundances, specifically the Firmicutes-to-Bacteroidetes ratio; Muribaculaceae, Ruminococcaceae, and Eggerthellaceae abundances at the family level; and Candidatus Arthromitus abundance at the genus level. CONCLUSION: These data indicate that NE inhibitor is a key treatment candidate to alleviate FUIIM by regulating abnormal inflammatory responses, intestinal barrier dysfunction, and gut microbiota imbalance.