Transcription factor FOXF1 identifies compartmentally distinct mesenchymal cells with a role in lung allograft fibrogenesis

FOXF1 reverses lung fibroblasts transdifferentiation via inhibiting TGF-β/SMAD2/3 pathway in silica-induced pulmonary fibrosis

Silicosis is one of the most common and severe types of pneumoconiosis and is characterized by lung dysfunction, persistent lung inflammation, pulmonary nodule formation, and irreversible pulmonary fibrosis. The transdifferentiation of fibroblasts into myofibroblasts is one of the main reasons for the exacerbation of silicosis. However, the underlying mechanism of transcription factors regulating silicosis fibrosis has not been clarified. The aim of this study was to investigate the potential mechanism of transcription factor FOXF1 in fibroblast transdifferentiation in silica-induced pulmonary fibrosis. Therefore, a silicosis mouse model was established, and we found that FOXF1 expression level was significantly down-regulated in the silicosis group, and after overexpression of FOXF1 by adeno-associated virus (AAV), FOXF1 expression level was up-regulated, and silicosis fibrosis was alleviated. In order to further explore the specific regulatory mechanism of FOXF1 in silicosis, we established a fibroblasts transdifferentiation model induced by TGF-β in vitro. In the model, the expression levels of SMAD2/3 and P-SMAD2/3 were up-regulated, but the expression levels of SMAD2/3 and P-SMAD2/3 were down-regulated, inhibiting transdifferentiation and accumulation of extracellular matrix after the overexpressed FOXF1 plasmid was constructed. However, after silencing FOXF1, the expression levels of SMAD2/3 and P-SMAD2/3 were further up-regulated, aggravating transdifferentiation and accumulation of extracellular matrix. These results indicate that the activation of FOXF1 in fibroblasts can slow down the progression of silicosis fibrosis by inhibiting TGF-β/SMAD2/3 classical pathway, which provides a new idea for further exploration of silicosis treatment.

Single-cell RNA sequencing identifies hippocampal microglial dysregulation in diet-induced obesity

Obesity is a growing global concern in adults and youth with a parallel rise in associated complications, including cognitive impairment. Obesity induces brain inflammation and activates microglia, which contribute to cognitive impairment by aberrantly phagocytosing synaptic spines. Local and systemic signals, such as inflammatory cytokines and metabolites likely participate in obesity-induced microglial activation. However, the precise mechanisms mediating microglial activation during obesity remain incompletely understood. Herein, we leveraged our mouse model of high-fat diet (HFD)-induced obesity, which mirrors human obesity, and develops hippocampal-dependent cognitive impairment. We assessed hippocampal microglial activation by morphological and single-cell transcriptomic analysis to evaluate this heterogeneous, functionally diverse, and dynamic class of cells over time after 1 and 3 months of HFD. HFD altered cell-to-cell communication, particularly immune modulation and cellular adhesion signaling, and induced a differential gene expression signature of protein processing in the endoplasmic reticulum in a time-dependent manner.

FOXF1 attenuates TGF‑β1‑induced bronchial epithelial cell injury by inhibiting CDH11‑mediated Wnt/β‑catenin signaling

Forkhead box F1 (FOXF1) has been reported to be associated with lung development. However, the role of FOXF1 in asthma is still not fully understood. In the present study, the biological role and the potential mechanism of FOXF1 was explored in transforming growth factor β1 (TGF-β1)-induced bronchial epithelial cell injury. Reverse transcription-quantitative PCR and western blotting were performed to detect the expression levels of FOXF1 and cadherin (CDH) 11 in TGF-β1-induced bronchial epithelial cells. Proliferation, apoptosis and inflammation were assessed using Cell Counting Kit-8 assay, flow cytometry, western blotting and ELISA. Fibrosis and epithelial-mesenchymal transition (EMT) were evaluated using immunofluorescence and western blotting. The expression levels of the proteins involved in the Wnt/β-catenin pathway were detected by western blotting. The results indicated that FOXF1 expression was downregulated, while CDH11 expression was upregulated in TGF-β1-treated BEAS-2B cells. FOXF1 overexpression promoted proliferation, inhibited induction of apoptosis and suppressed the inflammatory response of BEAS-2B cells exposed to TGF-β1. In addition, FOXF1 overexpression restrained TGF-β1-induced bronchial epithelial fibrosis and EMT and inhibited the activation of the Wnt/β-catenin pathway. CDH11 overexpression reversed the effects of FOXF1 overexpression on proliferation, apoptosis, fibrosis, EMT and inflammation by regulating the Wnt/β-catenin pathway. Collectively, the results of the present study suggested that FOXF1 regulated TGF-β1-induced BEAS-2B cell injury by inhibiting CDH11-mediated Wnt/β-catenin signaling. This may provide a novel therapeutic strategy for the treatment of asthma.

Gene expression profiles in mesenchymal stromal cells from bone marrow, adipose tissue and lung tissue of COPD patients and controls

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is characterized by irreversible lung tissue damage. Novel regenerative strategies are urgently awaited. Cultured mesenchymal stem/stromal cells (MSCs) have shown promising results in experimental models of COPD, but differences between sources may impact on their potential use in therapeutic strategies in patients.

AIM

To assess the transcriptome of lung-derived MSCs (LMSCs), bone marrow-derived MSCs (BM-MSC) and adipose-derived MSCs (AD-MSCs) from COPD patients and non-COPD controls.

METHODS

We studied differences in gene expression profiles between the MSC-subtypes, as well as between COPD and control using RNA sequencing (RNA-seq).

RESULTS

We show that besides heterogeneity between donors, MSCs from different sources have strongly divergent gene signatures. The growth factors FGF10 and HGF were predominantly expressed in LMSCs. MSCs from all sources displayed altered expression profiles in COPD, with most pronounced significantly up- and downregulated genes in MSCs from adipose tissue. Pathway analysis revealed that the most differentially expressed genes in COPD-derived AD-MSCs are involved in extracellular matrix (ECM) binding and expression. In LMSCs, the gene that differed most strongly between COPD and control was CSGALNACT1, an ECM modulating gene.

CONCLUSION

Autologous MSCs from COPD patients display abnormalities with respect to their transcriptome, which were surprisingly most profound in MSCs from extrapulmonary sources. LMSCs may be optimally equipped for lung tissue repair because of the expression of specific growth factor genes.

Reprogramming alveolar macrophage responses to TGF-β reveals CCR2+ monocyte activity that promotes bronchiolitis obliterans syndrome

Bronchiolitis obliterans syndrome (BOS) is a major impediment to lung transplant survival and is generally resistant to medical therapy. Extracorporeal photophoresis (ECP) is an immunomodulatory therapy that shows promise in stabilizing BOS patients, but its mechanisms of action are unclear. In a mouse lung transplant model, we show that ECP blunts alloimmune responses and inhibits BOS through lowering airway TGF-β bioavailability without altering its expression. Surprisingly, ECP-treated leukocytes were primarily engulfed by alveolar macrophages (AMs), which were reprogrammed to become less responsive to TGF-β and reduce TGF-β bioavailability through secretion of the TGF-β antagonist decorin. In untreated recipients, high airway TGF-β activity stimulated AMs to express CCL2, leading to CCR2+ monocyte-driven BOS development. Moreover, we found TGF-β receptor 2-dependent differentiation of CCR2+ monocytes was required for the generation of monocyte-derived AMs, which in turn promoted BOS by expanding tissue-resident memory CD8+ T cells that inflicted airway injury through Blimp-1-mediated granzyme B expression. Thus, through studying the effects of ECP, we have identified an AM functional plasticity that controls a TGF-β-dependent network that couples CCR2+ monocyte recruitment and differentiation to alloimmunity and BOS.

Lef1 is transcriptionally activated by Klf4 and suppresses hyperoxia-induced alveolar epithelial cell injury

PURPOSE

Bronchopulmonary dysplasia (BPD) is a long-term respiratory condition. More than a quarter of extremely premature newborns are harmed by BPD. At present, there are no apparent effective drugs or treatments for the condition. In this study, we aimed to investigate the functional role and mechanism of lymphoid enhancer-binding factor 1 (Lef1) in BPD in vitro.

MATERIALS AND METHODS

Blood samples from BPD patients and healthy volunteers were gathered, and an in vitro model of BPD was developed in alveolar epithelial cells (AECs) MLE-12 induced by hyperoxia. Then expression of krüppel-like factor 4 (KLF4/Klf4) and LEF1/Lef1 were evaluated. After Lef1 overexpressing plasmid and the vector were transfected into hyperoxia-induced MLE-12 cells, cell proliferation assays were carried out. Cell apoptosis was investigated by a flow cytometry assay, and apoptosis related proteins Bcl-2, cleaved-caspase 3 and 9 were analyzed by a western blot assay. The binding between Klf4 and Lef1 promoter predicted on the JASPAR website was verified using luciferase and ChIP assays. For further study of the mechanism of Klf4 and Lef1 in BPD, gain-of-function experiments were performed.

RESULTS

The mRNA levels of KLF4/Klf4 and LEF1/Lef1 were diminished in clinical BPD serum samples and hyperoxia-induced MLE-12 cells. Overexpression of Lef1 stimulated AEC proliferation and suppressed AEC apoptosis induced by hyperoxia. Mechanically, Klf4 bound to Lef1's promoter region and aids transcription. Moreover, the results of gain-of-function experiments supported that Klf4 could impede AEC damage induced by hyperoxia via stimulating Lef1.

CONCLUSION

Klf4 and Lef1 expression levels were declined in hyperoxia-induced AECs, and Lef1 could be transcriptionally activated by Klf4 and protect against hyperoxia-induced AEC injury in BPD. As a result, Lef1 might become a prospective therapeutic target for BPD.