Sox9-expressing cells promote regeneration after radiation-induced lung injury via the PI3K/AKT pathway

NLRP3 inflammasome mediates abnormal epithelial regeneration and distal lung remodeling in silica‑induced lung fibrosis

NOD-like receptor protein 3 (NLRP3) inflammasome is closely related to silica particle‑induced chronic lung inflammation but its role in epithelial remodeling, repair and regeneration in the distal lung during development of silicosis remains to be elucidated. The present study aimed to determine the effects of the NLRP3 inflammasome on epithelial remodeling and cellular regeneration and potential mechanisms in the distal lung of silica‑treated mice at three time points. Pulmonary function assessment, inflammatory cell counting, enzyme‑linked immunosorbent assay, histological and immunological analyses, hydroxyproline assay and western blotting were used in the study. Single intratracheal instillation of a silica suspension caused sustained NLRP3 inflammasome activation in the distal lung. Moreover, a time‑dependent increase in airway resistance and a decrease in lung compliance accompanied progression of pulmonary fibrosis. In the terminal bronchiole, lung remodeling including pyroptosis (membrane‑distributed GSDMD+), excessive proliferation (Ki67+), mucus overproduction (mucin 5 subtype AC and B) and epithelial‑mesenchymal transition (decreased E‑Cadherin+ and increased Vimentin+), was observed by immunofluorescence analysis. Notably, aberrant spatiotemporal expression of the embryonic lung stem/progenitor cell markers SOX2 and SOX9 and ectopic distribution of bronchioalveolar stem cells were observed in the distal lung only on the 7th day after silica instillation (the early inflammatory phase of silicosis). Western blotting revealed that the Sonic hedgehog/Glioma‑associated oncogene (Shh/Gli) and Wnt/β‑catenin pathways were involved in NLRP3 inflammasome activation‑mediated epithelial remodeling and dysregulated regeneration during the inflammatory and fibrotic phases. Overall, sustained NLRP3 inflammasome activation led to epithelial remodeling in the distal lung of mice. Moreover, understanding the spatiotemporal profile of dysregulated epithelial repair and regeneration may provide a novel therapeutic strategy for inhalable particle‑related chronic inflammatory and fibrotic lung disease.

Role of Sox9 in BPD and its effects on the Wnt/β-catenin pathway and AEC-II differentiation

The excessive activation of the Wnt/β-catenin signaling pathway is an important regulatory mechanism that underlies the excessive proliferation and impaired differentiation of type 2 alveolar epithelial cells (AEC-II) in bronchopulmonary dysplasia (BPD). Sox9 has been shown to be an important repressor of the Wnt/β-catenin signaling pathway and plays an important regulatory role in various pathophysiological processes. We found that the increased expression of Sox9 in the early stages of BPD could downregulate the expression of β-catenin and promote the differentiation of AEC-II cells into AEC-I, thereby alleviating the pathological changes in BPD. The expression of Sox9 in BPD is regulated by long noncoding RNA growth arrest-specific 5. These findings may provide new targets for the early intervention of BPD.

Effects of Therapeutic Platelet-Rich Plasma on Overactive Bladder via Modulating Hyaluronan Synthesis in Ovariectomized Rat

Postmenopausal women who have ovary hormone deficiency (OHD) may experience urological dysfunctions, such as overactive bladder (OAB) symptoms. This study used a female Sprague Dawley rat model that underwent bilateral ovariectomy (OVX) to simulate post-menopause in humans. The rats were treated with platelet-rich plasma (PRP) or platelet-poor plasma (PPP) after 12 months of OVX to investigate the therapeutic effects of PRP on OHD-induced OAB. The OVX-treated rats exhibited a decrease in the expression of urothelial barrier-associated proteins, altered hyaluronic acid (hyaluronan; HA) production, and exacerbated bladder pathological damage and interstitial fibrosis through NFƘB/COX-2 signaling pathways, which may contribute to OAB. In contrast, PRP instillation for four weeks regulated the inflammatory fibrotic biosynthesis, promoted cell proliferation and matrix synthesis of stroma, enhanced mucosal regeneration, and improved urothelial mucosa to alleviate OHD-induced bladder hyperactivity. PRP could release growth factors to promote angiogenic potential for bladder repair through laminin/integrin-α6 and VEGF/VEGF receptor signaling pathways in the pathogenesis of OHD-induced OAB. Furthermore, PRP enhanced the expression of HA receptors and hyaluronan synthases (HAS), reduced hyaluronidases (HYALs), modulated the fibroblast-myofibroblast transition, and increased angiogenesis and matrix synthesis via the PI3K/AKT/m-TOR pathway, resulting in bladder remodeling and regeneration.

Fractionated FLASH radiation in xenografted lung tumors induced FLASH effect at a split dose of 2 Gy

PURPOSE

To explore the minimum split dose of FLASH radiotherapy (FLASH).

MATERIAL AND METHODS

Lungs of nude mice were used to verify the capacity of normal tissue sparing of FLASH, while tumor-bearing nude mice were used to evaluate the curative power. Xenografted tumor models were established in Balb/c-nu mice using A549 cells at a concentration of 5 × 10 6 / 100   μ L . With the same total dose (20 Gy), the dose rate of FLASH was 200 Gy/s when conventional radiotherapy(CONV) was 0.033 Gy/s. Two schemes of FLASH irradiations were applied: single pulse (FLASH1) and ten pulses (FLASH10). Then, according to the different tissue types and irradiation schemes, mice were divided into eight groups: Control-T, CONV-T, FLASH1-T, FLASH10-T (T for tumor) and Control-L, CONV-L, FLASH1-L, FLASH10-L (L for lung). Evaluation of FLASH effect was based on the changes in tumor volume and pathological analysis of tumor and lung tissues before and after irradiation.

RESULTS

Compared to control group, the mean volume of tumors in nude mice increased slowly or decreased after irradiation with both FLASH and CONV (Control-T: 233.6± 55.19 mm3, CONV-T: 146.1± 50.62 mm3, FLASH1-T: 148± 18.83 mm3, FLASH10-T: 119.1± 50.62 mm3, p  ≤   . 05) . Tumor cells of irradiated groups had similar degrees of dissolution damage and inflammation, while the acute radiation pneumonia induced by FLASH was less severe. The pulmonary pathology of FLASH1-L and FLASH10-L were similar, and only a few neutrophils were observed. In addition to inflammatory cells, slight thickening of alveolar septum and obvious interstitial hemorrhage were also observed in the CONV-L group.

CONCLUSION

The FLASH effect was successfully reproduced in both single and fractionated irradiation, with 2 Gy being the minimum split dose to achieve the FLASH effect in existing experiments. It is suggested that the transient oxygen depletion might not be the only mechanism behind the FLASH effect.

Reassessing the embryonic origin and potential of craniofacial ectomesenchyme

Of all the cell types arising from the neural crest, ectomesenchyme is likely the most unusual. In contrast to the neuroglial cells generated by neural crest throughout the embryo, consistent with its ectodermal origin, cranial neural crest-derived cells (CNCCs) generate many connective tissue and skeletal cell types in common with mesoderm. Whether this ectoderm-derived mesenchyme (ectomesenchyme) potential reflects a distinct developmental origin from other CNCC lineages, and/or epigenetic reprogramming of the ectoderm, remains debated. Whereas decades of lineage tracing studies have defined the potential of CNCC ectomesenchyme, these are being revisited by modern genetic techniques. Recent work is also shedding light on the extent to which intrinsic and extrinsic cues determine ectomesenchyme potential, and whether maintenance or reacquisition of CNCC multipotency influences craniofacial repair.

Single-Cell RNA-Sequencing Reveals Epithelial Cell Signature of Multiple Subtypes in Chemically Induced Acute Lung Injury

Alveolar epithelial cells (AECs) play a role in chemically induced acute lung injury (CALI). However, the mechanisms that induce alveolar epithelial type 2 cells (AEC2s) to proliferate, exit the cell cycle, and transdifferentiate into alveolar epithelial type 1 cells (AEC1s) are unclear. Here, we investigated the epithelial cell types and states in a phosgene-induced CALI rat model. Single-cell RNA-sequencing of bronchoalveolar lavage fluid (BALF) samples from phosgene-induced CALI rat models (Gas) and normal controls (NC) was performed. From the NC and Gas BALF samples, 37,245 and 29,853 high-quality cells were extracted, respectively. All cell types and states were identified and divided into 23 clusters; three cell types were identified: macrophages, epithelial cells, and macrophage proliferating cells. From NC and Gas samples, 1315 and 1756 epithelial cells were extracted, respectively, and divided into 11 clusters. The number of AEC1s decreased considerably following phosgene inhalation. A unique SOX9-positive AEC2 cell type that expanded considerably in the CALI state was identified. This progenitor cell type may develop into alveolar cells, indicating its stem cell differentiation potential. We present a single-cell genome-scale transcription map that can help uncover disease-associated cytologic signatures for understanding biological changes and regeneration of lung tissues during CALI.

SRY-related high-mobility group box 9 (SOX9) alleviates cigarette smoke extract (CSE)-induced inflammatory injury in human bronchial epithelial cells by suppressing stromal interaction molecule 1 (STIM1) expression

BACKGROUND AND OBJECTIVE

Chronic obstructive pulmonary disease (COPD) is a chronic airway disease with airflow limitation and abnormal inflammatory response. It has been verified that SOX9 plays a key role in lung function of various lung diseases and SOX9 is closely associated with COPD. Additionally, literature has reported that STIM1 is involved in lung injury and is highly expressed in neutrophils from COPD patients. This study aimed to characterize the biological roles of SOX9 and STIM1 in the pathogenesis of COPD and to elucidate the regulatory mechanism.

METHODS

Human bronchial epithelial cells (BEAS-2B) were treated with CSE to construct in vitro COPD model. The levels of SOX9 and STIM1 in CSE-treated BEAS-2B cells were detected by western blot and RT-qPCR assay. Then, JASPAR datasets were utilized to analyze SOX9 binding sites in the promoter region of STIM1. Besides, luciferase reporter assay and ChIP assay were employed to validate the binding sites in STIM1 promoter region to SOX9. In addition, viability and apoptosis of BEAS-2B cells were assessed by utilizing MTT assay and TUNEL staining. ELISA kits and corresponding commercial kits were applied to measure the levels of TNF-α, IL-6, IL-1β, SOD, GSH-Px and MDA.

RESULTS

CSE treatment dose- and time-dependently reduced SOX9 expression in BEAS-2B cells. SOX9 overexpression enhanced the viability and suppressed the apoptosis of CSE-treated BEAS-2B cells as well as attenuated CSE-induced inflammation and oxidative stress. Then, it was validated that SOX9 bound to the promoter region of STIM1. Moreover, SOX9 overexpression-mediated impacts on cell viability, cell apoptosis, inflammation and oxidative stress in CSE-treated BEAS-2B cells were partially abolished by upregulation of STIM1.

CONCLUSION

To sum up, results here suggested that overexpression of SOX9 could mitigate inflammatory injury in CSE-treated bronchial epithelial cells by suppressing STIM1.