Heterogeneity of immune cells and their communications unveiled by transcriptome profiling in acute inflammatory lung injury.

Background: Acute Respiratory Distress Syndrome (ARDS) or its earlier stage Acute lung injury (ALI), is a worldwide health concern that jeopardizes human well-being. Currently, the treatment strategies to mitigate the incidence and mortality of ARDS are severely restricted. This limitation can be attributed, at least in part, to the substantial variations in immunity observed in individuals with this syndrome. Methods: Bulk and single cell RNA sequencing from ALI mice and single cell RNA sequencing from ARDS patients were analyzed. We utilized the Seurat program package in R and cellmarker 2.0 to cluster and annotate the data. The differential, enrichment, protein interaction, and cell-cell communication analysis were conducted. Results: The mice with ALI caused by pulmonary and extrapulmonary factors demonstrated differential expression including Clec4e, Retnlg, S100a9, Coro1a, and Lars2. We have determined that inflammatory factors have a greater significance in extrapulmonary ALI, while multiple pathways collaborate in the development of pulmonary ALI. Clustering analysis revealed significant heterogeneity in the relative abundance of immune cells in different ALI models. The autocrine action of neutrophils plays a crucial role in pulmonary ALI. Additionally, there was a significant increase in signaling intensity between B cells and M1 macrophages, NKT cells and M1 macrophages in extrapulmonary ALI. The CXCL, CSF3 and MIF, TGFß signaling pathways play a vital role in pulmonary and extrapulmonary ALI, respectively. Moreover, the analysis of human single-cell revealed DCs signaling to monocytes and neutrophils in COVID-19-associated ARDS is stronger compared to sepsis-related ARDS. In sepsis-related ARDS, CD8+ T and Th cells exhibit more prominent signaling to B-cell nucleated DCs. Meanwhile, both MIF and CXCL signaling pathways are specific to sepsis-related ARDS. Conclusion: This study has identified specific gene signatures and signaling pathways in animal models and human samples that facilitate the interaction between immune cells, which could be targeted therapeutically in ARDS patients of various etiologies.

Neutrophil extracellular traps and their implications in airway inflammatory diseases.

Neutrophil extracellular traps (NETs) are essential for immune defense and have been increasingly recognized for their role in infection and inflammation. In the context of airway inflammatory diseases, there is growing evidence suggesting the involvement and significance of NETs. This review aims to provide an overview of the formation mechanisms and components of NETs and their impact on various airway inflammatory diseases, including acute lung injury/ARDS, asthma, chronic obstructive pulmonary disease (COPD) and cystic fibrosis. By understanding the role of NETs in airway inflammation, we can gain valuable insights into the underlying pathogenesis of these diseases and identify potential targets for future therapeutic strategies that either target NETs formation or modulate their harmful effects. Further research is warranted to elucidate the complex interactions between NETs and airway inflammation and to develop targeted therapies that can effectively mitigate their detrimental effects while preserving their beneficial functions in host defense.

Nanoformulated ABT-199 to effectively target Bcl-2 at mitochondrial membrane alleviates airway inflammation by inducing apoptosis.

Elimination of airway inflammatory cells is essential for asthma control. As Bcl-2 protein is highly expressed on the mitochondrial outer membrane in inflammatory cells, we chose a Bcl-2 inhibitor, ABT-199, which can inhibit airway inflammation and airway hyperresponsiveness by inducing inflammatory cell apoptosis. Herein, we synthesized a pH-sensitive nanoformulated Bcl-2 inhibitor (Nf-ABT-199) that could specifically deliver ABT-199 to the mitochondria of bronchial inflammatory cells. The proof-of-concept study of an inflammatory cell mitochondria-targeted therapy using Nf-ABT-199 was validated in a mouse model of allergic asthma. Nf-ABT-199 was proven to significantly alleviate airway inflammation by effectively inducing eosinophil apoptosis and inhibiting both inflammatory cell infiltration and mucus hypersecretion. In addition, the nanocarrier or Nf-ABT-199 showed no obvious influence on cell viability, airway epithelial barrier and liver function, implying excellent biocompatibility and with non-toxic effect. The nanoformulated Bcl-2 inhibitor Nf-ABT-199 accumulates in the mitochondria of inflammatory cells and efficiently alleviates allergic asthma.

Melatonin Attenuates Pain Hypersensitivity and Decreases Astrocyte-Mediated Spinal Neuroinflammation in a Rat Model of Oxaliplatin-Induced Pain.

Neuroinflammatory response in spinal dorsal horn has been demonstrated to be a critical factor in oxaliplatin-induced pain. Melatonin has been shown to have anti-inflammatory and anti-allodynia effects in both preclinical and clinical studies. In the present study, we investigated the role of systemic administration of melatonin on oxaliplatin-induced pain. Intraperitoneal (i.p.) injection with oxaliplatin induced significantly mechanical allodynia and thermal hyperalgesia. Melatonin (i.p.) significantly alleviated mechanical allodynia and thermal hyperalgesia in the oxaliplatin but not sham-treated rats. The attenuation of nociceptive response persisted at least to 3 days after melatonin injection, throughout the entire observing window. Immunohistochemistry showed that oxaliplatin induced a significant increase of glial fibrillary acidic protein (GFAP) immunodensities, which could be suppressed by melatonin. Western blotting showed that GFAP protein levels were significantly elevated in the oxaliplatin-vehicle group. Melatonin significantly decreased oxaliplatin-induced upregulation of GFAP expressions. Oxaliplatin injection also enhanced the messenger RNA (mRNA) expressions of cytokines including interleukin-1ß (IL-1ß) and tumor necrosis factor-α (TNF-α) and chemokines including monocyte chemoattractant protein-1 (MCP-1) and monocyte inflammatory protein-1 (MIP-1α) in the spinal dorsal horn, which could be significantly repressed by melatonin. In vitro study showed that mRNA levels of TNF-α, IL-1ß, MCP-1, and MIP-1α in primarily astrocytes were significantly increased after lipopolysaccharide (LPS, 1 µg/ml) stimulation. Melatonin (10 and 100 µM) greatly inhibited synthesis of these inflammatory mediators, in a dose-related manner. Conclusively, our data provide a novel implication of anti-nociceptive mechanism of melatonin in chemotherapy-related pain.

Bcl-2 inhibitors reduce steroid-insensitive airway inflammation.

BACKGROUND: Asthmatic inflammation is dominated by accumulation of either eosinophils, neutrophils, or both in the airways. Disposal of these inflammatory cells is the key to disease control. Eosinophilic airway inflammation is responsive to corticosteroid treatment, whereas neutrophilic inflammation is resistant and increases the burden of global health care. Corticosteroid-resistant neutrophilic asthma remains mechanistically poorly understood and requires novel effective therapeutic strategies. OBJECTIVE: We sought to explore the underlying mechanisms of airway inflammation persistence, as well as corticosteroid resistance, and to investigate a new strategy of effective treatment against corticosteroid-insensitive neutrophilic asthma. METHODS: Mouse models of either eosinophil-dominated or neutrophil-dominated airway inflammation were used in this study to test corticosteroid sensitivity in vivo and in vitro. We also used vav-Bcl-2 transgenic mice to confirm the importance of granulocytes apoptosis in the clearance of airway inflammation. Finally, the Bcl-2 inhibitors ABT-737 or ABT-199 were tested for their therapeutic effects against eosinophilic or neutrophilic airway inflammation and airway hyperresponsiveness. RESULTS: Overexpression of Bcl-2 protein was found to be responsible for persistence of granulocytes in bronchoalveolar lavage fluid after allergic challenge. This was important because allergen-induced airway inflammation aggravated and persisted in vav-Bcl-2 transgenic mice, in which nucleated hematopoietic cells were overexpressed with Bcl-2 and resistant to apoptosis. The Bcl-2 inhibitors ABT-737 or ABT-199 play efficient roles in alleviation of either eosinophilic or corticosteroid-resistant neutrophilic airway inflammation by inducing apoptosis of immune cells, such as eosinophils, neutrophils, TH2 cells, TH17 cells, and dendritic cells. Moreover, these inhibitors were found to be more efficient than steroids to induce granulocyte apoptosis ex vivo from patients with severe asthma. CONCLUSION: Apoptosis of inflammatory cells is essential for clearance of allergen-induced airway inflammation. The Bcl-2 inhibitors ABT-737 or ABT-199 might be promising drugs for the treatment of airway inflammation, especially for corticosteroid-insensitive neutrophilic airway inflammation.

Exogenous interleukin-17A inhibits eosinophil differentiation and alleviates allergic airway inflammation.

IL-17 is known to play important roles in immune and inflammatory disease, such as in asthma, but its functions in allergic airway inflammation are still controversial, and the molecular mechanisms mediating these functions remain unclear. Increased production of eosinophils in bone marrow and their emergence in the airway have been linked to the onset and progression of allergic asthma. In this study, we investigated the effects of exogenous IL-17 on allergic airway inflammation and explored the underlying molecular mechanisms through eosinophil generation. Exogenous IL-17 significantly attenuated the features of allergic inflammation induced by ovalbumin in mice. It inhibited eosinophil differentiation both in vivo and in vitro, accompanied by down-regulated expression of CC chemokine receptor 3, GATA binding protein 1 (GATA-1), and GATA binding protein 2 (GATA-2), as well as reduced formation of common myeloid progenitors and eosinophil progenitors, but without influencing eosinophil apoptosis. IL-17 also significantly decreased the number of eosinophils in IL-5-transgenic mice, although it notably increased the levels of IL-3, IL-5, and granulocyte/macrophage colony-stimulating factor. In addition, IL-17 had little effect on secretion of the inflammatory cytokines by eosinophils. Neutralization of endogenous IL-17 significantly augmented eosinophil recruitment in the airways. Together, these findings suggest that exogenous IL-17 protects against allergic airway inflammation, most likely through inhibition of the eosinophil differentiation in bone marrow.

Balance of apoptotic cell death and survival in allergic diseases.

Allergic diseases result from over-reaction of the immune system in response to exogenous allergens, where inflammatory cells have constantly extended longevity and contribute to an on-going immune response in allergic tissues. Here, we review disequilibrium in the death and survival of epithelial cells and inflammatory cells in the pathological processes of asthma, atopic dermatitis, and other allergic diseases.