Anti-Inflammatory and Immunomodulatory Role of Bone Marrow-Derived MSCs in Mice with Acute Lung Injury

Bone marrow mesenchymal stem cells-derived exosomes ameliorate LPS-induced acute lung injury by miR-223-regulated alveolar macrophage M2 polarization

Numerous studies have shown that the M2 polarization of alveolar macrophages (AM) plays a protective role in acute lung injury (ALI). Mesenchymal stem cells (MSCs) secreted exosomes have been reported to be involved in inflammatory diseases by the effects of polarized M1/M2 macrophage populations. However, whether bone marrow mesenchymal stem cells (BMMSCs) derived exosomes could protect from ALI and its mechanisms are still unclear. Here, we explored the role of exosomes from BMMSC in rat AM polarization and the lipopolysaccharide- (LPS-) induced ALI rat model. Furthermore, the levels of exosomal miR-223 in BMMSCs were measured by RT-qPCR. Additionally, miR-223 mimics and its inhibitors were used to verify the vital role of miR-223 of BMMSCs-derived exosomes in the polarization of M2 macrophages. The results showed that BMMSCs-derived exosomes were taken up by the AM. Exosomes derived from BMMSCs promoted M2 polarization of AM in vitro. BMMSCs exosomes effectively mitigated pathological injuries, lung edema, and the inflammation of rats from LPS-induced ALI, accompanied by an increase of M2 polarization of AM in lung tissue. Interestingly, we also found that miR-223 was enriched in BMMSCs-derived exosomes, and overexpression of miR-223 in BMMSCs-derived exosomes promoted M2 polarization of AM while depressing miR-223 showed opposite effects in AM. The present study demonstrated that BMMSCs-derived exosomes triggered alveolar M2 polarization to improve inflammation by transferring miR-223, which may provide new therapeutic strategies in ALI.

[Gastrodin injection alleviates lung injury caused by focal cerebral ischemia in rats through NGF/TrkA pathway-mediated activation of the anti-inflammatory pathway]

OBJECTIVE

To investigate the therapeutic mechanism of gastrodin injection for alleviating lung injury caused by focal cerebral ischemia in rats and the role of the NGF-TrkA pathway in mediating this effect.

METHODS

Forty SD rats were equally randomized into normal group, sham-operated group, model group and gastrodin group, and in the latter two groups, rat models of focal cerebral ischemia were established by embolization of the right middle cerebral artery. After successful modeling, the rats were treated with intraperitoneal injection of gastrodin injection at the daily dose of 10 mg/kg for 14 days. After the treatment, the wet/dry weight ratio of the lung tissue was determined, the pathological changes in the lung tissue were observed using HE staining, and the levels of IL-10 and TNF-α in the arterial blood were detected with ELISA. The expressions of NF-κB p65 and TNF-α in the lung tissue were detected with Western blotting, and the expressions of NGF and TrkA were detected using immunohistochemical staining and Western blotting.

RESULTS

Compared with the normal control and sham-operated groups, the rats in the model group showed obvious inflammatory lung injury, significantly increased wet/ dry weight ratio of the lungs (P < 0.01), increased TNF-α level in arterial blood (P < 0.01), and significantly up-regulated protein expressions of NF-κB p65 (P < 0.01), TNF-α (P < 0.01), NGF (P < 0.05) and TrkA(P < 0.05) in the lung tissue. Treatment with gastrodin injection obviously alleviated lung inflammation, decreased the wet/dry weight ratio of the lungs (P < 0.05), and significantly lowered TNF-α level (P < 0.01) and increased IL-10 level in the arterial blood in the rat models (P < 0.01); gastrodin injection also significantly decreased the protein expressions of NF-κB p65 and TNF-α (P < 0.05) and up-regulated the expressions of NGF and TrkA in the lung tissue of the rats (P < 0.05).

CONCLUSION

The NGF/TrkA pathway may participate in cerebral ischemia-induced inflammatory lung injury, which can be obviously alleviated by gastrodin through the activation of the anti-inflammatory pathway mediated by the NGF/TrkA pathway.

Bergamottin alleviates LPS-induced acute lung injury by inducing SIRT1 and suppressing NF-κB

Acute lung injury (ALI) is associated with a high mortality due to inflammatory cell infiltration and lung edema. The development of ALI commonly involves the activation of NF-κB. Since bergamottin is a natural furanocoumarin showing the ability to inhibit the activation of NF-κB, in this study we aimed to determine the effect of bergamottin on ALI. RAW264.7 mouse macrophages were pre-treated with bergamottin and then stimulated with LPS. Macrophage inflammatory responses were examined. Bergamottin (50 mg/kg body mass) was intraperitoneally administrated to mice 12 h before injection of LPS, and the effect of bergamottin on LPS-induced ALI was evaluated. Our results showed that LPS exposure led to increased production of TNF-α, IL-6, and monocyte chemoattractant protein-1 (MCP-1), which was impaired by bergamottin pre-treatment. In vivo studies confirmed that bergamottin pre-treatment suppressed LPS-induced lung inflammation and edema and reduced the levels of pro-inflammatory cytokines in lung tissues and bronchoalveolar lavage fluids. Mechanistically, bergamottin blocked LPS-induced activation of NF-κB signaling in lung tissues. Additionally, bergamottin treatment reduced NF-κB p65 protein acetylation, which was coupled with induction of SIRT1 expression. In conclusion, our results reveal the anti-inflammatory property of bergamottin in preventing ALI. Induction of SIRT1 and inhibition of NF-κB underlies the anti-inflammatory activity of bergamottin.

Immunosuppressive effect of mesenchymal stem cells on lung and gut CD8+ T cells in lipopolysaccharide-induced acute lung injury in mice

Objectives

Acute lung injury (ALI) not only affects pulmonary function but also leads to intestinal dysfunction, which in turn contributes to ALI. Mesenchymal stem cell (MSC) transplantation can be a potential strategy in the treatment of ALI. However, the mechanisms of synergistic regulatory effects by MSCs on the lung and intestine in ALI need more in‐depth study.

Materials and methods

We evaluated the therapeutic effects of MSCs on the murine model of lipopolysaccharide (LPS)‐induced ALI through survival rate, histopathology and bronchoalveolar lavage fluid. Metagenomic sequencing was performed to assess the gut microbiota. The levels of pulmonary and intestinal inflammation and immune response were assessed by analysing cytokine expression and flow cytometry.

Results

Mesenchymal stem cells significantly improved the survival rate of mice with ALI, alleviated histopathological lung damage, improved intestinal barrier integrity, and reduced the levels of inflammatory cytokines in the lung and gut. Furthermore, MSCs inhibited the inflammatory response by decreasing the infiltration of CD8⁺ T cells in both small‐intestinal lymphocytes and Peyer's patches. The gut bacterial community diversity was significantly altered by MSC transplantation. Furthermore, depletion of intestinal bacterial communities with antibiotics resulted in more severe lung and gut damages and mortality, while MSCs significantly alleviated lung injury due to their immunosuppressive effect.

Conclusions

The present research indicates that MSCs attenuate lung and gut injury partly via regulation of the immune response in the lungs and intestines and gut microbiota, providing new insights into the mechanisms underlying the therapeutic effects of MSC treatment for LPS‐induced ALI.