Discussion
With the development of experimental technology, especially electron microscopy, it is known that in patients with CRSwNP, the patient’s nasal mucosal epithelial cells are edema degeneration, the barrier function of the nasal mucosa is impaired, and the resistance to harmful substances and microorganisms is insufficient, which leads to repeated inflammatory reactions in the nasal cavity, and then gradually lead to the remodeling of nasal mucosa. Transmission electron microscope observation showed that the CRSwNP tissue showed edema of nasal mucosa epithelial cells, a large number of mitochondrial hyperplasia in the cytoplasm, endoplasmic reticulum edema and the formation of a large number of swallowed vesicles; Submembrane edema, dilation of small blood vessels and capillaries in the tissue, intrinsic interstitial edema accompanied by a large number of inflammatory cells10-13. Also in clinical diagnosis, the most common pathological classification of CRSwNP disease is edema polyps, accounting for about 85%-90%.
In addition to functional endoscopic surgical resection, glucocorticoids are widely used in clinical treatment of CRSwNP, and their therapeutic effect has reached consensus. Local and systemic application of glucocorticoids in the nasal cavity is considered to be effective for the treatment of CRSwNP. Cochrane evaluation showed that glucocorticoids can effectively improve systemic symptoms of patients with nasal polyps and reduce edema of nasal polyps. This mechanism is proved to be that glucocorticoid can quickly enter the cell nucleus and interact with the glucocorticoid response element on the chromosome by binding to its receptor, initiating or inhibiting downstream gene expression, thereby exerting a physiological role. However, although there is a clear understanding of the structural changes of CRSwNP tissues and cells, the mechanism of the formation of CRSwNP tissue edema is still unclear.
According to the mechanism of glucocorticoid treatment of CRSwNP, we tried to co-cultured CRSwNP cells with a glucocorticoid-rich medium to observe the changes in edmea of CRSwNP, and then analyze the expression of gene transcriptomes to compare with normal cultured CRSwNP cells. Then we analyzed the differentially expressed genes of the two groups, so as to predict the mechanism of nasal polyp edema is related to that signal, while using CRISPR-Case9 gene editing technology for simple verification.
In immunofluorescence staining of CRSwNP tissues, we found that a large number of interstitial cells edema increased, a large number of inflammatory cells infiltration. After the intervention of glucocorticoid, the edema of CRSwNP cells is significantly reduced by the difference between the CON group and the DSTG group. GO enrichment, KEGG analysis and PPI network analysis revealed that this mechanism is closely related to the ribosome pathway involved in RPL26. This proves that the RPL26 gene may play an important physiological role in the mechanism of CRSwNP cells edema.
Cell Research reported that RPL26 is the main substrate for ubiquitination of mammalian cells and a special regulator of ubiquitination of ribosomal proteins5. The RPL26 gene encodes the ribosomal protein of the L24P family and is highly expressed in the mitochondria in the cytoplasm, which can regulate mitochondrial function. RPL26 encodes a protein that can effectively eliminate ectopic stasis in the cell after ubiquitination, and this effect is not through the traditional eukaryotic endoplasmic reticulum-related protein degradation protein quality control system (ERAD) or cytosolic ribosome The quality control (RQC) system works, but transports the accumulated polypeptide from the endoplasmic reticulum to the lysosome in the cytoplasm for degradation14, 15, 16.
We established RPL26 silencing and overexpressing CRSwNP cell system. The study found that after RPL26 silencing expression, the degree of CRSwNP tissue edema increased; but after RPL26 overexpression, CRSwNP edema was significantly reduced. In the apoptosis experiment, no matter whether it is RPL26 silencing system or RPL26 over-expression, there is no significant difference in apoptosis between the two groups of experiments and normal CRSwNP tissue. Highly expressed rpl26 can effectively reduce the degree of cell edema and have little effect on apoptosis. The higher apoptosis rate was detected in anti-rpl26 group, which may be related to excessive cell edema. This result is consistent with the results of pre-transcriptome genetic analysis, confirming that RPL26 plays an important role in the regulation of CRSwNP tissue edema. Using online gene annotation sites and ncbi database to query information, the function of RPL26 may be completed through the ribosomal signaling pathway17,18,19, but this conjecture still needs further experimental confirmation.