PARK2 Induces Osteoclastogenesis through Activation of the NF-κB Pathway

Cell life-or-death events in osteoporosis: All roads lead to mitochondrial dynamics

Mitochondria exhibit heterogeneous shapes and networks within and among cell types and tissues, also in normal or osteoporotic bone tissues with complex cell types. This dynamic characteristic is determined by the high plasticity provided by mitochondrial dynamics and is stemmed from responding to the survival and functional requirements of various bone cells in a specific microenvironments. In contrast, mitochondrial dysfunction, induced by dysregulation of mitochondrial dynamics, may act as a trigger of cell death signals, including common apoptosis and other forms of programmed cell death (PCD). These PCD processes consisting of tightly structured cascade gene expression events, can further influence the bone remodeling by facilitating the death of various bone cells. Mitochondrial dynamics, therefore, drive the bone cells to stand at the crossroads of life and death by integrating external signals and altering metabolism, shape, and signal-response properties of mitochondria. This implies that targeting mitochondrial dynamics displays significant potential in treatment of osteoporosis. Considerable effort has been made in osteoporosis to emphasize the parallel roles of mitochondria in regulating energy metabolism, calcium signal transduction, oxidative stress, inflammation, and cell death. However, the emerging field of mitochondrial dynamics-related PCD is not well understood. Herein, to bridge the gap, we outline the latest knowledge on mitochondrial dynamics regulating bone cell life or death during normal bone remodeling and osteoporosis.

PARK2 as a susceptibility factor for nontuberculous mycobacterial pulmonary disease

BACKGROUND

The genetic signatures associated with the susceptibility to nontuberculous mycobacterial pulmonary disease (NTM-PD) are still unknown. In this study, we performed RNA sequencing to explore gene expression profiles and represent characteristic factor in NTM-PD.

METHODS

Peripheral blood samples were collected from patients with NTM-PD and healthy individuals (controls). Differentially expressed genes (DEGs) were identified by RNA sequencing and subjected to functional enrichment and immune cell deconvolution analyses.

RESULTS

We enrolled 48 participants, including 26 patients with NTM-PD (median age, 58.0 years; 84.6% female), and 22 healthy controls (median age, 58.5 years; 90.9% female). We identified 21 upregulated and 44 downregulated DEGs in the NTM-PD group compared to those in the control group. NTM infection did not have a significant impact on gene expression in the NTM-PD group compared to the control group, and there were no differences in the proportion of immune cells. However, through gene ontology (GO), gene set enrichment analysis (GSEA), and protein-protein interaction (PPI) analysis, we discovered that PARK2 is a key factor associated with NTM-PD. The PARK2 gene, which is linked to the ubiquitination pathway, was downregulated in the NTM-PD group (fold change, - 1.314, P = 0.047). The expression levels of PARK2 remained unaltered after favorable treatment outcomes, suggesting that the gene is associated with host susceptibility rather than with the outcomes of infection or inflammation. The area under the receiver operating characteristic curve for the PARK2 gene diagnosing NTM-PD was 0.813 (95% confidence interval, 0.694-0.932).

CONCLUSION

We identified the genetic signatures associated with NTM-PD in a cohort of Korean patients. The PARK2 gene presents as a potential susceptibility factor in NTM-PD .

Advances in the Pathogenesis of Steroid-Associated Osteonecrosis of the Femoral Head

Osteonecrosis of the femoral head (ONFH) is a refractory orthopedic condition characterized by bone cell ischemia, necrosis, bone trabecular fracture, and clinical symptoms such as pain, femoral head collapse, and joint dysfunction that can lead to disability. The disability rate of ONFH is very high, which imposes a significant economic burden on both families and society. Steroid-associated osteonecrosis of the femoral head (SANFH) is the most common type of ONFH. However, the pathogenesis of SANFH remains unclear, and it is an urgent challenge for orthopedic surgeons to explore it. In this paper, the pathogenesis of SANFH and its related signaling pathways were briefly reviewed to enhance comprehension of the pathogenesis and prevention of SANFH.

Diabetic Rats Induced Using a High-Fat Diet and Low-Dose Streptozotocin Treatment Exhibit Gut Microbiota Dysbiosis and Osteoporotic Bone Pathologies

Type 2 diabetes mellitus (T2DM) presents a challenge for individuals today, affecting their health and life quality. Besides its known complications, T2DM has been found to contribute to bone/mineral abnormalities, thereby increasing the vulnerability to bone fragility/fractures. However, there is still a need for appropriate diagnostic approaches and targeted medications to address T2DM-associated bone diseases. This study aims to investigate the relationship between changes in gut microbiota, T2DM, and osteoporosis. To explore this, a T2DM rat model was induced by combining a high-fat diet and low-dose streptozotocin treatment. Our findings reveal that T2DM rats have lower bone mass and reduced levels of bone turnover markers compared to control rats. We also observe significant alterations in gut microbiota in T2DM rats, characterized by a higher relative abundance of Firmicutes (F) and Proteobacteria (P), but a lower relative abundance of Bacteroidetes (B) at the phylum level. Further analysis indicates a correlation between the F/B ratio and bone turnover levels, as well as between the B/P ratio and HbA1c levels. Additionally, at the genus level, we observe an inverse correlation in the relative abundance of Lachnospiraceae. These findings show promise for the development of new strategies to diagnose and treat T2DM-associated bone diseases.

Recent advances of NFATc1 in rheumatoid arthritis-related bone destruction: mechanisms and potential therapeutic targets

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease characterized by inflammation of the synovial tissue and joint bone destruction, often leading to significant disability. The main pathological manifestation of joint deformity in RA patients is bone destruction, which occurs due to the differentiation and proliferation of osteoclasts. The transcription factor nuclear factor-activated T cell 1 (NFATc1) plays a crucial role in this process. The regulation of NFATc1 in osteoclast differentiation is influenced by three main factors. Firstly, NFATc1 is activated through the upstream nuclear factor kappa-B ligand (RANKL)/RANK signaling pathway. Secondly, the Ca2+-related co-stimulatory signaling pathway amplifies NFATc1 activity. Finally, negative regulation of NFATc1 occurs through the action of cytokines such as B-cell Lymphoma 6 (Bcl-6), interferon regulatory factor 8 (IRF8), MAF basic leucine zipper transcription factor B (MafB), and LIM homeobox 2 (Lhx2). These three phases collectively govern NFATc1 transcription and subsequently affect the expression of downstream target genes including TRAF6 and NF-κB. Ultimately, this intricate regulatory network mediates osteoclast differentiation, fusion, and the degradation of both organic and inorganic components of the bone matrix. This review provides a comprehensive summary of recent advances in understanding the mechanism of NFATc1 in the context of RA-related bone destruction and discusses potential therapeutic agents that target NFATc1, with the aim of offering valuable insights for future research in the field of RA. To assess their potential as therapeutic agents for RA, we conducted a drug-like analysis of potential drugs with precise structures.

Avenanthramide-C Shows Potential to Alleviate Gingival Inflammation and Alveolar Bone Loss in Experimental Periodontitis

Periodontal disease is a chronic inflammatory disease that leads to the gradual destruction of the supporting structures of the teeth including gums, periodontal ligaments, alveolar bone, and root cementum. Recently, interests in alleviating symptoms of periodontitis (PD) using natural compounds is increasing. Avenanthramide-C (Avn-C) is a polyphenol found only in oats. It is known to exhibit various biological properties. To date, the effect of Avn-C on PD pathogenesis has not been confirmed. Therefore, this study aimed to verify the protective effects of Avn-C on periodontal inflammation and subsequent alveolar bone erosion in vitro and in vivo. Upregulated expression of catabolic factors, such as matrix metalloproteinase 1 (MMP1), MMP3, interleukin (IL)-6, IL-8, and COX2 induced by lipopolysaccharide and proinflammatory cytokines, IL-1β, and tumor necrosis factor α (TNF-α), was dramatically decreased by Avn-C treatment in human gingival fibroblasts and periodontal ligament cells. Moreover, alveolar bone erosion in the ligature-induced PD mouse model was ameliorated by intra-gingival injection of Avn-C. Molecular mechanism studies revealed that the inhibitory effects of Avn-C on the upregulation of catabolic factors were mediated via ERK (extracellular signal-regulated kinase) and NF-κB pathway that was activated by IL-1β or p38 MAPK and JNK signaling that was activated by TNF-α, respectively. Based on this study, we recommend that Avn-C may be a new natural compound that can be applied to PD treatment.

Guizhi Shaoyao Zhimu granules attenuate bone destruction in mice with collagen-induced arthritis by promoting mitophagy of osteoclast precursors to inhibit osteoclastogenesis

BACKGROUND

Guizhi Shaoyao Zhimu decoction, a traditional Chinese medicine formula used empirically for the treatment of rheumatoid arthritis (RA), has been shown to alleviate bone destruction in rats with collagen-induced arthritis (CIA).

PURPOSE

The aim of this study is to characterize the effects of Guizhi Shaoyao Zhimu granules (GSZGs) on bone destruction in RA and the underlying mechanism.

STUDY DESIGN

A CIA arthritis model using DBA/1 mice. The animals were divided into a normal group; CIA model group; low, medium, and high-dose GSZG groups (3, 6, and 9 g/kg/day); and a methotrexate group (1.14 mg/kg/w). In vitro, a cytokine induced osteoclastogenesis model was established.

METHODS

After 28 days of treatment, the paw volume was measured, bone destruction was examined by micro-CT, and the generation of osteoclasts in bone tissue was evaluated via tartrate-resistant acid phosphatase (TRAP) staining. Furthermore, the inhibitory effect and underlying mechanism of action of GSZG on RANKL-induced osteoclastogenesis were investigated in vitro.

RESULTS

The in vivo analyses demonstrated that the paw volume and degree of bone erosion of mice in the medium- and high-dose GSZG groups were significantly decreased compared to the CIA model group. In addition, GSZG treatment suppressed the excessive generation of osteoclasts in the bone tissue of CIA mice. In vitro, GSZG inhibited RANKL-induced osteoclastogenesis and osteoclast-mediated bone resorption. Specifically, it only inhibited the generation of osteoclast precursors (OCPs); it had no significant effect on the fusion of OCPs or maturation of osteoclasts. Finally, we showed that the inhibitory effect of GSZG on osteoclastogenesis was related to the promotion of PTEN-induced kinase protein 1 (PINK1)/Parkin pathway-mediated mitophagy of osteoclast precursors, which was verified using a PINK1 knockdown small interfering RNA in OCPs.

CONCLUSION

These findings indicate that GSZG is a candidate for the treatment of bone destruction in RA and provide a more detailed elucidation of the mechanism of GSZG anti-RA bone erosion, i.e., inhibition of the ROS/NF-κB axis through the PINK1/Parkin-mediated mitochondrial autophagic pathway to inhibit osteoclast precursor production, compared to the published literature.

A computational approach based on weighted gene co-expression network analysis for biomarkers analysis of Parkinson's disease and construction of diagnostic model

Background

Parkinson's disease (PD) is a common age-related chronic neurodegenerative disease. There is currently no affordable, effective, and less invasive test for PD diagnosis. Metabolite profiling in blood and blood-based gene transcripts is thought to be an ideal method for diagnosing PD.

Aim

In this study, the objective is to identify the potential diagnostic biomarkers of PD by analyzing microarray gene expression data of samples from PD patients.

Methods

A computational approach, namely, Weighted Gene Co-expression Network Analysis (WGCNA) was used to construct co-expression gene networks and identify the key modules that were highly correlated with PD from the GSE99039 dataset. The Least Absolute Shrinkage and Selection Operator (LASSO) regression analysis was performed to identify the hub genes in the key modules with strong association with PD. The selected hub genes were then used to construct a diagnostic model based on logistic regression analysis, and the Receiver Operating Characteristic (ROC) curves were used to evaluate the efficacy of the model using the GSE99039 dataset. Finally, Reverse Transcription-Polymerase Chain Reaction (RT-PCR) was used to validate the hub genes.

Results

WGCNA identified two key modules associated with inflammation and immune response. Seven hub genes, LILRB1, LSP1, SIPA1, SLC15A3, MBOAT7, RNF24, and TLE3 were identified from the two modules and used to construct diagnostic models. ROC analysis showed that the diagnostic model had a good diagnostic performance for PD in the training and testing datasets. Results of the RT-PCR experiments showed that there were significant differences in the mRNA expression of LILRB1, LSP1, and MBOAT7 among the seven hub genes.

Conclusion

The 7-gene panel (LILRB1, LSP1, SIPA1, SLC15A3, MBOAT7, RNF24, and TLE3) will serve as a potential diagnostic signature for PD.