LTF induces senescence and degeneration in the meniscus via the NF-κB signaling pathway: A study based on integrated bioinformatics analysis and experimental validation

Abstract

Background: The functional integrity of the meniscus continually decreases with age, leading to meniscal degeneration and gradually developing into osteoarthritis (OA). In this study, we identified diagnostic markers and potential mechanisms of action in aging-related meniscal degeneration through bioinformatics and experimental verification.Methods: Based on the GSE98918 dataset, common differentially expressed genes (co-DEGs) were screened using differential expression analysis and the WGCNA algorithm, and enrichment analyses based on Gene Ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways were further performed. Next, the co-DEGs were imported into the STRING database and Cytoscape to construct a protein‒protein interaction (PPI) network and further validated by three algorithms in cytoHubba, receiver operating characteristic (ROC) curve analysis and the external GSE45233 dataset. Moreover, the diagnostic marker lactotransferrin (LTF) was verified in rat models of senescence and replicative cellular senescence via RT‒qPCR, WB, immunohistochemistry and immunofluorescence, and then the potential molecular mechanism was explored by loss of function and overexpression of LTF.Results: According to the analysis of the GSE98918 dataset, we identified 52 co-DEGs (42 upregulated genes and 10 downregulated genes) in the OA meniscus. LTF, screened out by Cytoscape, ROC curve analysis in the GSE98918 dataset and another external GSE45233 dataset, might have good predictive power in meniscal degeneration. Our experimental results showed that LTF expression was statistically increased in the meniscal tissue of aged rats (24 months) and senescent passage 5th (P5) meniscal cells. In P5 meniscal cells, LTF knockdown inhibited the NF-κB signaling pathway and alleviated senescence. LTF overexpression in passage 0 (P0) meniscal cells increased the expression of senescence-associated secretory phenotype (SASP) and induced senescence by activating the NF-κB signaling pathway. However, the senescence phenomenon caused by LTF overexpression could be reversed by the NF-κB inhibitor pyrrolidine dithiocarbamate (PDTC).Conclusion: For the first time, we found that increased expression of LTF was observed in the aging meniscus and could induce meniscal senescence and degeneration by activating the NF-κB signaling pathway. These results revealed that LTF could be a potential diagnostic marker and therapeutic target for age-related meniscal degeneration.

A Novel Role for Protein Tyrosine Phosphatase 1B in Alleviating Chondrocyte Senescence

“…By activation of the NF-B signaling pathway, LTF might cause meniscal senescence and degeneration. These findings suggested that LTF may serve as a possible treatment target for meniscal degeneration associated with aging as well as a diagnostic marker . In primary chondrocytes, DPP-4 expression was linked to increased senescence-related β-galactosidase activity, p16 expression, senescence-related gene and catabolic gene expression (ADAMTS5, MMP13, IL6, and IL8), increased senescence-associated secretory phenotype secretion, and decreased anabolic gene expression (COL2A1 and ACAN) .…”

“…These findings suggested that LTF may serve as a possible treatment target for meniscal degeneration associated with aging as well as a diagnostic marker. 41 In primary chondrocytes, DPP-4 expression was linked to increased senescence-related β-galactosidase activity, p16 expression, senescence-related gene and catabolic gene expression (ADAMTS5, MMP13, IL6, and IL8), increased senescence-associated secretory phenotype secretion, and decreased anabolic gene expression (COL2A1 and ACAN). 42 In this study, 25 hub cellular senescence-related DEGs were selected, their important biological roles were described, and correlation networks were built by using a variety of bioinformatic techniques.…”

Deciphering the impact of aging on splenic endothelial cell heterogeneity and immunosenescence through single-cell RNA sequencing analysis

“…For example, LTF binding to CD14 receptor competes with the bacterial LPS (product of dying bacteria) [ 44 ] and can attenuate NF-κB-induced transcription of genes for various inflammatory mediators [ 45 ]. Also, it is reported that high LTF expression might contribute to meniscal aging and degeneration through the NF-κB signaling pathway [ 46 ].Therefore, we could speculate that the endothelial-immunology transition is regulated by Ltf.…”

“…S8 D). It is well-known that LTF could activate the NF-κB signaling pathway, promoting macrophage activation [ 43 ].Also, it is reported that high LTF expression might contribute to meniscal aging and degeneration through the NF-κB signaling pathway [ 46 ].Therefore, we could speculate that the endothelial-immunology transition is regulated by Ltf.…”

Metabolic pathways in immune senescence and inflammaging: Novel therapeutic strategy for chronic inflammatory lung diseases. An EAACI position paper from the Task Force for Immunopharmacology

“…NF-κB controls the SASP as many components are NF-κB target genes 39 and increased NF-κB phosphorylation has been detected in senescent cells of different origin. [39][40][41][42][43] An increase in secretory activity is driven by the high NAD+/NADH ratio produced by the high mobility group A proteins (HMGA)-nicotinamide phosphoribosyltransferase (NAMPT) axis, along with increased glycolysis and mitochondrial respiration. SASP factors in turn alter NAD+ metabolism and stimulate the expression on immune cells of CD38, a NADase which leads to NAD+ reduction.…”