Apoptosis of the Tracheal Epithelium Can Increase the Number of Recipient Bone Marrow–Derived Myofibroblasts in Allografts and Exacerbate Obliterative Bronchiolitis After Tracheal Transplantation in Mice

Triggering receptor expressed on myeloid cells-1 aggravates obliterative bronchiolitis via enhancing the proinflammatory phenotype of macrophages

BACKGROUND

Triggering Receptor Expressed on Myeloid cells-1 (TREM-1) plays an important role in innate immune system. However, whether and how TREM-1 contributes to obliterative bronchiolitis (OB) progression remains unclear.

METHODS

A murine orthotopic tracheal transplantation model was constructed to mimic the pathogenesis of OB. qPCR and immunoblotting were used to measure TREM-1 expression. RNA sequencing was used to investigate the impact of TREM-1 on proinflammatory phenotype of macrophages. Trem-1 knockout mice and Nlrp3 knockout mice were generated to investigate the role of the TREM-1/NLRP3 pathway in the proinflammatory phenotype of macrophages. The infiltration of immune cells within the grafts was quantified using immunofluorescence staining. Flow cytometry was used to detect the proportion of different immune cells in mice spleen and the expression levels of iNOS and co-stimulatory molecules in macrophages.

RESULTS

The expression of TREM-1 was upregulated in the mouse OB model. Genetic ablation or pharmacological inhibition of TREM-1 ameliorated OB, whereas the stimulation of TREM-1 using anti-TREM-1 agonistic antibody exacerbated OB. Moreover, Trem-1 ablation reduced the infiltration of iNOS+ macrophages and limited the T cell responses. In vitro studies revealed that Trem-1 deletion impaired the proinflammatory function and antigen presentation ability of macrophages. Additionally, Trem-1 knockout inhibited the activation of NLRP3 signaling pathway. NLRP3 overexpression restored the proinflammatory phenotype of Trem-1 knockout macrophages.

CONCLUSIONS

These findings indicated that TREM-1 could promote the proinflammatory phenotype of macrophages through NLRP3 inflammasome activation, thereby exacerbating OB progression. These findings indicated that TREM-1 may serve as a therapeutic target for OB treatment.

Preventing CXCL12 elevation helps to reduce acute exacerbation of COPD in individuals co-existing type-2 diabetes: A bioinformatics and clinical pharmacology study

AIMS

To investigate the immunology shared mechanisms underlying chronic obstructive pulmonary disease (COPD) and type 2 diabetes mellitus (T2DM) and examine the impact of anti-diabetic drugs on acute exacerbation of COPD (AECOPD).

METHODS

We analyzed GSE76925, GSE76894, GSE37768, and GSE25724 to identify differentially expressed genes. Hub-genes were identified through protein-protein interaction network analysis and evaluated by the receiver operating characteristic curve. CXCL12 emerged as a robust biomarker, and its correlation with lung function and CD8+ T cells were further quantified and validated. The activated signaling pathways were inferred through Gene set enrichment analysis (GSEA). The retrospective clinical analysis was executed to identify the influence of dipeptidyl peptidase-4 inhibitors (DPP-4i) on CXCL12 and evaluate the drug's efficacy in AECOPD.

RESULTS

The significant up-regulation of CXCL12 expression in patients with two diseases were revealed. CXCL12 exhibited a negative correlation with pulmonary function (r = -0.551, p < 0.05). Consistent with analysis in GSE76925 and GSE76894, the positive correlation between the proportion of CD8+ T cells was demonstrated(r=0.469, p<0.05). GSEA identified "cytokines interaction" as an activated signaling pathway, and the clinical study revealed the correlation between CXCL12 and IL-6 (r=0.668, p<0.05). In patients with COPD and T2DM, DDP-4i treatment exhibited significantly higher serum CXCL12, compared to GLP-1RA. Analysis of 187 COPD patients with T2DM indicated that the DPP-4i group had a higher frequency of AECOPD compared to the GLP-1RA group (OR 1.287, 95%CI [1.018-2.136]).

CONCLUSIONS

CXCL12 may represent a therapeutic target for COPD and T2DM. GLP-1RA treatment may be associated with lower CXCL12 levels and a lower risk of AECOPD compared to DPP-4i treatment.

CLINICAL TRIAL REGISTRATION

China Clinical Trial Registration Center（ChiCTR2200055611）.

Role of transforming growth factor-β in airway remodelling in bronchiolitis obliterans

Airway remodelling is the main pathological mechanism of bronchiolitis obliterans (BO). Several studies have found that transforming growth factor-β (TGF-β) expression is increased in BO during airway remodelling, where it plays an important role in various biological processes by binding to its receptor complex to activate multiple signalling proteins and pathways. This review examines the role of TGF-β in airway remodelling in BO and its potential as a therapeutic target, highlighting the mechanisms of TGF-β activation and signalling, cellular targets of TGF-β actions, and research progress in TGF-β signalling and TGF-β-mediated processes.

The Effects of Rapamycin on the Proliferation, Migration, and Apoptosis of Human Tracheal Fibroblasts (HTrF) and Human Tracheal Epithelial Cells (HTEpiC)

Background: Restenosis after airway stenting needs to be addressed urgently. Rapamycin has been proven to inhibit restenosis elsewhere. This study aimed at observing its effects on the respiratory tract. Methods: CCK-8, wound healing, Transwell and apoptosis assays were performed to detect the effects of rapamycin on the survival, migration, and apoptosis, respectively, of human tracheal fibroblasts (HTrF) and human tracheal epithelial cells (HTEpiC). Results: The effective concentrations of paclitaxel, mitomycin C and rapamycin on HTrF were 10⁻⁷–10⁻⁴ mol/L, 10⁻⁶–10⁻⁴ mol/L, and 10⁻⁵–10⁻⁴ mol/L, respectively. At the effective concentrations, the inhibition rates of paclitaxel on HTEpiC were (43.03 ± 1.12)%, (49.49 ± 0.86)%, (55.22 ± 1.43)%, and (93.19 ± 0.45)%; the inhibition rates of mitomycin C on HTEpiC were (88.11 ± 0.69)%, (93.82 ± 0.96)%, and (94.94 ± 0.54)%; the inhibition rates of rapamycin on HTEpiC were (10.19 ± 0.35)% and (94.55 ± 0.71)%. At the concentration of (1–4) × 10⁻⁵ mol/L, the inhibition rate of rapamycin on HTrF was more than 50%, and that on HTEpiC was less than 20% (p < 0.05). Conclusions: Compared to paclitaxel and mitomycin C, rapamycin had the least effect on HTEpiC while effectively inhibiting HTrF. The optimum concentration range was (1–4) × 10⁻⁵ mol/L.

Nlrp3 Inflammasome Inhibitor MCC950 Ameliorates Obliterative Bronchiolitis by Inhibiting Th1/Th17 Response and Promoting Treg Response After Orthotopic Tracheal Transplantation in Mice

BACKGROUND

Obliterative bronchiolitis (OB) remains the major complication limiting long-term survival of patients after lung transplantation. We aimed to explore the effects of the selective NACHT, LRR, and PYD domains-containing protein 3 (Nlrp3) inflammasome inhibitor MCC950 on the pathogenesis of OB.

METHODS

Mouse orthotopic tracheal transplants were performed to mimic OB. MCC950 (50 mg/kg) or saline was intraperitoneally injected daily. The luminal occlusion rate and collagen deposition were evaluated by hematoxylin and eosin and Masson's trichrome staining, respectively. Infiltration of CD4+, CD8+ T cells, and neutrophils was detected with immunohistochemical staining. The frequencies of T helper 1 cell (Th1), T helper 17 cell (Th17), and regulatory T cells (Treg) were measured by flow cytometry. Cytokine levels were measured by ELISA kits.

RESULTS

MCC950 treatment significantly inhibited Nlrp3 inflammasome activation after allogeneic tracheal transplant and markedly decreased the luminal occlusion rate and collagen deposition in the allograft. The numbers of infiltrating CD4+, CD8+ T cells, and neutrophils in the allograft were also significantly reduced by MCC950 treatment. MCC950 dramatically decreased the frequencies of Th1/Th17 cells and the levels of interferon gamma/interleukin (IL)-17A and increased the Treg cell frequencies and IL-10 level; however, these effects were abolished by the addition of IL-1β and IL-18 both in vitro and in vivo. OB was also rescued by the addition of IL-1β and/or IL-18.

CONCLUSIONS

Blocking Nlrp3 inflammasome activation with MCC950 ameliorates OB lesions. The mechanistic analysis showed that MCC950 regulated the balance of Th1/Th17 and Treg cells and that this process is partially mediated by inhibition of IL-1β and IL-18. Therefore, targeting the Nlrp3 inflammasome is a promising strategy for controlling OB after lung transplantation.

Bioinformatics analysis and verification of gene targets for benign tracheal stenosis

Background

Tracheal injury could cause intratracheal scar hyperplasia which in turn causes benign tracheal stenosis (TS). With the increasing use of mechanical ventilation and ventilator, the incidence of TS is increasing. However, the molecular mechanisms of TS have not been elucidated. It is significant to further explore the molecular mechanisms of TS.

Methods

The repeatability of public data was verified. Differently expressed genes (DEGs) and most significant genes were identified between TS and normal samples. Enrichment analysis of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) were analyzed. The comparative toxicogenomics database were analyzed. TS patients were recruited and RT‐qPCR were performed to verify the most significant genes.

Results

There exist strong correlations among samples of TS and normal group. There was a total of 194 DEGs, including 61 downregulated DEGs and 133 upregulated DEGs. GO were significantly enriched in mitotic nuclear division, cell cycle, and cell division. Analysis of KEGG indicated that the top pathways were cell cycle, and p53 pathway. MKI67(OMIM:176741), CCNB1(OMIM:123836), and CCNB2(OMIM:602755) were identified as the most significant genes of TS, and validated by the clinical samples.

Conclusion

Bioinformatics methods might be useful method to explore the mechanisms of TS. In addition, MKI67, CCNB1, and CCNB2 might be the most significant genes of TS.

Combined treatment with sinomenine and acupuncture on collagen-induced arthritis through the NF-κB and MAPK signaling pathway

Sinomenine is a monomer extracted from the traditional Chinese medicine plant Sabia japonica, which possesses several pharmacological properties including prominent abirritation, mitigation, anti-inflammation, immune suppression, cough relief, stimulation of histamine release, decrease in blood pressure and antiarrhythmia. Sinomenine is clinically employed to treat rheumatic disease. To investigate the impact of combined sinomenine treatment with acupuncture on the progression of arthritis and explore the potential underlying molecular mechanisms, the present study analyzed a collagen-induced arthritis model. Results from the combined curative (CC) treatment group (combined treatment with sinomenine and acupuncture) demonstrated a decrease in volume changes and arthritis score changes within rat paws, and increased the overall body weight in arthritic rats. CC treatment significantly decreased tumor necrosis factor α, interleukin (IL)-6, IL-1β and IL-8 serum levels in arthritic rats. CC treatment significantly increased superoxide dismutase and inhibited malondialdehyde levels in arthritic rats. The protein expression of cyclooxygenase-2, inducible nitric oxide synthase, matrix metalloproteinase (MMP)2 and MMP9 in arthritic rats was suppressed owing to CC treatment. Finally, nuclear factor κB and phosphorylated p38 mitogen-activated protein kinase (MAPK) protein expression in arthritic rats were also suppressed following CC treatment. The results indicate that the combined treatment of sinomenine and acupuncture on collagen-induced arthritis takes effect through the nuclear factor κB and MAPK signaling pathway.