ABSTRACT
Objective:To evaluate the role of orphan nuclear receptor Nur77 in tunicamycin(TM)-induced injury to hippocampal neurons and the relationship with endoplasmic reticulum stress in mice.Methods:Mouse HT22 cells were divided into 4 groups ( n=10 each) using a random number table method: control group (C group), Nur77 specific agonist Csn-B group (Csn-B group), endoplasmic reticulum stress inducer TM group (TM group), and TM+ Csn-B group. Cells in C group were cultured for 24 h under normal condition. In Csn-B group, Csn-B at a final concentration of 10 μg/ml was added to the culture medium, and the cells were incubated for 24 h. In TM group, TM at a final concentration of 200 ng/ml was added to the culture medium and the cells were incubated for 24 h to induce cell endoplasmic reticulum stress injury. Cells in TM+ Csn-B group were pretreated with Csn-B at a final concentration of 10 μg/ml for 15 min, then TM at a final concentration of 200 ng/ml was added, and the cells were co-incubated for 24 h. The cell viability was examined by CCK-8 assay kit after treatment in each group. The expression of endoplasmic reticulum stress-related protein CCAAT/enhancer-binding protein homologous protein (CHOP), glucose regulated protein 78 (GRP78)and apoptosis-associated protein Bcl-2, Bax, caspase-3 and cleaved-caspase-3 was detected by Western blot. Results:Compared with C group, the cell viability was significantly decreased, and the expression of CHOP, GRP78, Bax and cleaved-caspase-3 was up-regulated, and the expression of Bcl-2 and caspase-3 was down-regulated in TM group ( P<0.05 or 0.01). Compared with TM group, the cell viability was significantly increased, the expression of CHOP, GRP78, Bax and cleaved-caspase-3 was down-regulated, and the expression of Bcl-2 and caspase-3 was up-regulated in TM+ Csn-B group ( P<0.05 or 0.01). Conclusions:Orphan nuclear receptor Nur77 is involved in TM-induced injury to hippocampal neurons, which is related to activation of the endoplasmic reticulum stress in mice.
ABSTRACT
Periprosthetic joint infection (PJI) is one of the destructive complications after artificial joint replacement, which leads to postoperative joint pain, prolonged hospital stays, repeated multiple operations, dysfunction and even mortality. However, there is no specific diagnosis method for PJI. Although some progress has been made in the research of pathogenic microorganisms, diagnostic criteria, prevention strategies and treatment regimens of PJI in recent years, the quick and accurate diagnose and reducing of postoperative PJI is still the hotspot and difficulty in the field of artificial joint replacement. Gram-positive bacteria are the most common pathogenic bacteria, the prevalence of multidrug resistant pathogens, mixed bacterial infections and culture negative bacteria remain increasing. The epidemiological data of pathogen can guide clinical diagnosis and empirical use of antibiotics, which can help reducing of resistant bacteria. The International Consensus Meeting (ICM) proposed new diagnostic criteria, refined secondary criteria and assigned detailed scoring rules. New biochemical markers (such as leucocyte esterase and α-defensin, etc.), sonication of prosthesis combined with gene detection, imaging detection (such as 3-phase bone scanning labeled with technetium-99m, etc.), and next-generation sequencing is helpful to improve the accuracy of PJI diagnosis. Scientific and standardized perioperative management programs and new preventive measures, such as intraoperative application of vancomycin powder and diluted iodophor irrigation, are benefit to prevent and reduce the occurrence of PJI. Two-stage revision is still the standard intervention for chronic PJI, while one-stage revision combined with intra-articular antibiotics injection can effectively eradicate PJI in patients with acute or some chronic PJI with clear pathogenic bacteria.
ABSTRACT
Objective:To explore the effect of cholesterol on the expression of genes for matrix synthesis and degradation of human meniscal fibrochondrocytes and its mechanism.Methods:Meniscal tissue was taken from patients undergoing arthroscopic surgery to extract fibrochondrocytes. The cells were divided into a control group in which the normal cells were not processed, a positive control group in which interleukin-1 β was used to create a degeneration model, and 2 treatment groups which were subjected to treatment with 15 and 30 μg/mL cholesterol respectively. Safranin O staining, β-galactosidase staining and enzymic kits were used to detect the morphology and total cholesterol (TCH) content of meniscal fibrochondrocytes in the 4 groups. Immunofluorescence and western blot were used to detect the protein expression of type Ⅰcollagen precursor α1 (COL1A1) and type Ⅱ collagen precursor α1 (COL2A1). RT-qPCR was used to detect the mRNA expression of COL1A1, COL2A1, matrix metalloproteinase (MMP) 3, MMP9, MMP13, and genes related to cholesterol efflux pathways [like liver X receptor α (LXR α), ATP binding cassette transporter A1 (ABCA1) and ABCG1]. Results:There was no significant difference between the control and the positive control groups in the TCH content in human meniscal fibrochondrocytes ( P>0.05). The treatments with 15 and 30 μg/mL cholesterol resulted in significantly increased TCH contents in human meniscal fibrochondrocytes in the treatment groups ( P<0.05). Compared with the control group, the mRNA expression of LXR α, ABCA1 and ABCG1 was significantly decreased in the treatment groups ( P<0.05), and the meniscal fibrochondrocytes in the positive group and the treatment groups presented with a lower density, chaotic distribution and obvious signs of degradation. Compared with the control groups, the mRNA expression of matrix synthesis genes (COL1A1 and COL2A1) in the meniscal fibrochondrocytes was significantly inhibited while the mRNA expression of matrix degradation metalloenzymes (MMP3, MMP9 and MMP13) was significantly promoted ( P<0.05). Conclusion:Cholesterol may inhibit the cholesterol efflux pathways of meniscal fibrochondrocytes, and thus cause accumulation of cholesterol in the meniscal fibrochondrocytes, eventually leading to degeneration of meniscus.