Osteoimmunology: Could inhibition of IL-1 and TNF improve healing of meniscal lesions and prevent the development of osteoarthritis?

Identification of cuproptosis-related subtypes, characterization of immune microenvironment infiltration, and development of a prognosis model for osteoarthritis

Background

Osteoarthritis (OA) is a prevalent chronic joint disease with an obscure underlying molecular signature. Cuproptosis plays a crucial role in various biological processes. However, the association between cuproptosis-mediated immune infifiltration and OA progression remains unexplored. Therefore, this study elucidates the pathological process and potential mechanisms underlying cuproptosis in OA by constructing a columnar line graph model and performing consensus clustering analysis.

Methods

Gene expression profifile datasets GSE12021, GSE32317, GSE55235, and GSE55457 of OA were obtained from the comprehensive gene expression database. Cuproptosis signature genes were screened by random forest (RF) and support vector machine (SVM). A nomogram was developed based on cuproptosis signature genes. A consensus clustering was used to distinguish OA patients into different cuproptosis patterns. To quantify the cuproptosis pattern, a principal component analysis was developed to generate the cuproptosis score for each sample. Single-sample gene set enrichment analysis (ssGSEA) was used to provide the abundance of immune cells in each sample and the relationship between these significant cuproptosis signature genes and immune cells.To quantify the cuproptosis pattern, a principal component analysis technique was developed to generate the cuproptosis score for each sample. Cuproptosis-related genes were extracted and subjected to differential expression analysis to construct a disease prediction model and confifirmed by RT-qPCR.

Results

Seven cuproptosis signature genes were screened (DBT, LIPT1, GLS, PDHB, FDX1, DLAT, and PDHA1) to predict the risk of OA disease. A column line graph model was developed based on these seven cuproptosis signature genes, which may assist patients based on decision curve analysis. A consensus clustering method was used to distinguish patients with disorder into two cuproptosis patterns (clusters A and B). To quantify the cuproptosis pattern, a principal component analysis technique was developed to generate the cuproptosis score for each sample. Furthermore, the OA characteristics of patients in cluster A were associated with the inflflammatory factors IL-1b, IL-17, IL-21, and IL-22, suggesting that the cuproptosis signature genes play a vital role in the development of OA.

Discussion

In this study, a risk prediction model based on cuproptosis signature genes was established for the fifirst time, and accurately predicted OA risk. In addition, patients with OA were classifified into two cuproptosis molecule subtypes (clusters A and B); cluster A was highly associated with Th17 immune responses, with higher IL-1b, IL-17, and IL-21 IL-22 expression levels, while cluster B had a higher correlation with cuproptosis. Our analysis will help facilitate future research related cuproptosis-associated OA immunotherapy. However, the specifific mechanisms remain to be elucidated.

Inhibition of Toll-Like Receptor 4 Signaling Pathway Accelerates the Repair of Avascular Necrosis of Femoral Epiphysis through Regulating Macrophage Polarization in Perthes Disease

BACKGROUND

Legg-Calvé-Perthes disease (LCPD) is still a refractory disease in children's orthopedics. With the introduction of the concept of "osteoimmunology", the immune-inflammatory mechanisms between bone and immune system have become a research focus of LCPD. However, few studies have reported on the pathological role of inflammation-related receptors such as toll-like receptors (TLRs) as well as immune cells such as macrophages in LCPD. This study was for investigating the mechanism of TLR4 signaling pathway on the direction of macrophage polarization and the repair of avascular necrosis of femoral epiphysis in LCPD.

METHODS

With GSE57614 and GSE74089, differentially expressed genes were screened. Through enrichment analysis and protein-protein interaction network, the functions of TLR4 were explored. Furthermore, immunohistochemistry, enzyme-linked immunosorbent assay (ELISA), hematoxylin & eosin (H&E) staining, micro-CT, tartrate-resistant acid phosphatase (TRAP) dyeing and western blotting were performed for determining the influences of TAK-242 (a TLR4 inhibitor) on the repair of avascular necrosis of femoral epiphysis in rat models.

RESULTS

Totally 40 co-expression genes were screened as well as enriched in TLR4 signaling pathway. Immunohistochemistry and ELISA analyses certified that TLR4 facilitated macrophage polarization toward the M1 phenotype and prevented macrophage polarization toward the M2 phenotype. Besides, the results of H&E and TRAP staining, micro-CT, and western blotting showed that TAK-242 can inhibit osteoclastogenesis and promote osteogenesis.

CONCLUSION

Inhibition of TLR4 signaling pathway accelerated the repair of avascular necrosis of femoral epiphysis by regulating macrophage polarization in LCPD.

Effects of Hesperidin on H₂O₂-Treated Chondrocytes and Cartilage in a Rat Osteoarthritis Model

Background

The purpose of this research was to investigate the effects of hesperidin on hydrogen peroxide (H₂O₂)-induced chondrocytes injury and cartilage degeneration in a rat model of osteoarthritis (OA).

Material/Methods

Chondrocytes were isolated from rat knee joints and treated with hesperidin alone or combined with H₂O₂. Then, Cell Counting Kit-8 (CCK-8) assay was used to assess cell viability. Activity of reactive oxygen species (ROS) and levels of malondialdehyde (MDA) were estimated. Cell apoptosis was assessed by flow cytometry assay. In addition, gene expression levels were measured for caspase 3, tumor necrosis factor-alpha (TNF-α), interleukin-1beta (IL-1β), collagen type II (Col2a1), aggrecan, (sex-determining region Y)-box 9 (SOX9), matrix metalloproteinase (MMP)-13, and inducible nitric oxide synthase (iNOS) through quantitative real-time polymerase chain reaction (qPCR). To examine the effects on cartilage destruction in vivo, hesperidin or vehicle control were orally administrated in a surgically-induced osteoarthritis (OA) model.

Results

The results indicated that hesperidin pretreatment of chondrocytes reduce H₂O₂-induced cytotoxicity and apoptosis. Hesperidin pretreatment decreased the formation of MDA and intracellular ROS, including chondrocyte apoptosis. Hesperidin also reversed the activity of H₂O₂ on inhibiting the Col2a1, aggrecan, and SOX9 gene expression and increasing the gene expression of caspase 3, IL-1β, TNFα, iNOS, and MMP13. In addition, hesperidin administration markedly attenuated cartilage destruction and reduced IL-1β and TNF-α levels in a surgically-induced OA model.

Conclusions

Our study suggests that hesperidin can prevent H₂O₂-induced chondrocytes injury through its antioxidant effects in vitro and reduce cartilage damage in a rat model of OA.

Cyclin D1 Gene Silencing Promotes IL-1β-Induced Apoptosis in Rat Chondrocytes

This study investigated the effects of cyclin D1 gene silencing on cell proliferation and apoptosis of interleukin-1β (IL-1β)-induced osteoarthritis (OA) chondrocytes. Chondrocytes from healthy sprague-dawley rats were divided into blank, OA model (chondrocytes underwent IL-1β inducement), OA trial (chondrocytes underwent IL-1β inducement with cyclin D1-shRNA treatment), and negative control (NC; chondrocytes underwent IL-1β inducement and control-shRNA treatment) groups. Cell proliferation was assessed by CCK-8 assay, and cell cycle and apoptosis by flow cytometry. qRT-PCR and Western blotting were performed to detect cyclin D1 and apoptosis-related factors expression levels. Chondrocyte proliferation increased after 72-96 h after incubation. The OA trial group exhibited reduced cell proliferation at 48, 72, and 96 h after treatment. The OA model, OA trial, and NC groups all contained more cells arrested in G1 phase and had higher apoptosis rates than the blank group. Additionally, the OA trial group contained more cells arrested in G1 phase, with increased apoptosis rates compared to the OA model and NC groups. The OA model group had lowest expression of cyclin D1 whereas the blank group contained the highest among the four groups. qRT-PCR also showed that the OA model, OA trial, and NC groups all had increased expression levels of Bax and reduced expression levels of Bcl-2 and P53 compared to the blank group, whereby by the OA group had the most significant change. The combined evidence in our study shows that cyclin D1 gene silencing suppresses proliferation and induces apoptosis of rat chondrocytes in IL-1β-induced OA. J. Cell. Biochem. 119: 290-299, 2018. © 2017 Wiley Periodicals, Inc.

Interleukin-1β and tumor necrosis factor-α increase stiffness and impair contractile function of articular chondrocytes

Interleukin-1β (IL-1β) and tumor necrosis factor-α (TNF-α) are major proinflammatory cytokines involved in osteoarthritis (OA). These cytokines disturb chondrocyte metabolism by suppressing the synthesis of extracellular matrix proteins and stimulating the release of catabolic proteases, but little is known about their role in chondrocyte mechanics. Thus, the aim of this study was to measure the effects of IL-1β and TNF-α on the mechanical properties of the chondrocytes. Chondrocytes from goat knee joints were cultured in 96-well plates. The cellular stiffness and contractile function were probed using optical magnetic twisting cytometry, the cytoskeleton and the expression of extracellular matrix proteins were visualized using immunofluorescent staining, and chondrocyte phenotypical expression was measured by western blot analysis. Results showed that chondrocyte stiffness was dramatically decreased by disruption of F-actin but was unaffected by disruption of the intermediate filament vimentin. Treatment with 10 ng/ml IL-1β or 40 ng/ml TNF-α for 24 h substantially increased the expression level of F-actin and cellular stiffness, and impaired cell stiffening in response to the contractile agonist histamine, but these effects were blocked by the Rho-associated protein kinase inhibitor Y27632. In conclusion, IL-1β and TNF-α substantially change the mechanical properties of the chondrocytes in vitro. While changes of chondrocyte mechanics in vivo during OA progression remain unclear, this finding reveals a prominent role of these cytokines in cellular mechanics and provides insight for anti-cytokine therapies of OA.