Ossification of the posterior longitudinal ligament related genes identification using microarray gene expression profiling and bioinformatics analysis

Integrating Bioinformatic Strategies with Real-World Data to Infer Distinctive Immunocyte Infiltration Landscape and Immunologically Relevant Transcriptome Fingerprints in Ossification of Ligamentum Flavum

Purpose

Ossification of the ligamentum flavum (OLF) is a multifactorial disease characterized by an insidious and debilitating process of abnormal bone formation in ligamentum tissues. However, its definite pathogenesis has not been fully elucidated. Potential links between the immune system and various forms of heterotopic ossification have been discussed for many years, whereas no research investigated the immune effects on the initiation and development of OLF. Therefore, we attempt to shed light on this issue.

Methods

A series of bioinformatic algorithms were integrated to evaluate the immune score and the immunocyte infiltration patterns between OLF and normal samples, screen OLF-related and immune-related differentially expressed genes (OIDEGs), and analyze their biological functions. Correlation analysis inferred OIDEGs-related differentially expressed lncRNAs (OIDELs) and infiltrating immune cells (OIICs) to construct an immunoregulatory network.

Results

Differential immune score and immune cell infiltration were determined between two groups, and 10 OIDEGs with diverse biological function annotations were identified and verified. A lncRNA-gene-immunocyte regulatory network further revealed 10 OIDEGs, 41 OIDELs and 7 OIICs that were highly correlated. Among them, CD1E and STAT3 were predicted as hub genes whether at the expression level or interaction level. cDCs emerged as having the most prominent differences and the highest degree of connectivity. FO393414.3, AC096734.1, LINC01137 and DLX6-AS1 with the greatest number of OIDEGs were thought to be more likely to participate in immunoregulation of OLF.

Conclusion

This is the first research to preliminarily elucidate OLF-related immunocyte infiltration landscape and immune-associated transcriptome signatures based on bioinformatic strategies and real-world data, which may provide compelling insights into the pathogenesis and therapeutic targets of OLF.

Whole-genome sequencing reveals novel genes in ossification of the posterior longitudinal ligament of the thoracic spine in the Chinese population

BACKGROUND

Ossification of the posterior longitudinal ligament (OPLL) of the spine is a complex, multifactorial disease. Although several genes that are linked to cervical OPLL susceptibility have been reported, specific genetic studies regarding thoracic OPLL are lacking. Whole-genome sequencing has been considered as an efficient strategy to search for disease-causing genes.

METHODS

We analysed whole-genome sequences in a cohort of 25 unrelated patients with thoracic OPLL. Bioinformatics analysis and various algorithms were used to predict deleterious variants. Sanger sequencing was used to confirm the variants.

RESULTS

Four deleterious mutations in three genes (c.2716C>T (p.Arg906Cys) in collagen type VI α6 (COL6A6); c.1946G>C (p.Gly649Ala) in collagen type IX α1 (COL9A1); and c.301T>C (p.Ser101Pro) and c.171A>G (p.Ile57Met) in toll-like receptor 1 (TLR1)) were successfully identified. All the variants were confirmed by Sanger sequencing.

CONCLUSION

The novel deleterious mutations of the three genes may contribute to the development of thoracic OPLL.

Role of Cx43-Mediated NFкB Signaling Pathway in Ossification of Posterior Longitudinal Ligament: An In Vivo and In Vitro Study

STUDY DESIGN

In vivo and in vitro experiments.

OBJECTIVE

To illustrate the further molecular mechanism of Cx43-mediated osteoblastic differentiation of ligament cells.

SUMMARY OF BACKGROUND DATA

Ossification of the posterior longitudinal ligament (OPLL) is one of the main causes of myelopathy in Asians, but its etiology has not been clarified. We have previously found the mechanical stress can upregulate Cx43 expression in ligament cells, which transduces mechanical signal to promote osteoblastic differentiation.

METHODS

The posterior longitudinal ligaments were collected intraoperatively. Ligament fibroblasts were isolated and cultured, and an in vitro mechanical loading model was established. In vivo and in vitro expression levels of Cx43 protein were compared between OPLL and non-OPLL patients. The activation of nuclear factor (NF)-κB (p65) signal and related inflammatory responses were detected in ligament cells under mechanical loading. The mechanical stress-induced inflammatory response and osteoblastic differentiation of OPLL cells were investigated after the treatment with Cx43 siRNA or NFкB (p65) inhibitor.

RESULTS

We first confirmed higher Cx43 levels in both in vivo ligament tissue from OPLL patients and in vitro cultured OPLL cells. We also found NFκB (p65) signal and related inflammatory response were activated by mechanical stimulation. The activation of NFκB (p65) signal was dependent upon Cx43, as its knockdown reduced signal. Moreover, treatment with Cx43 siRNA or NFкB (p65) inhibitor significantly decreased the mechanical-induced inflammation response, but partly attenuated mechanical-stimulated osteoblastic differentiation of OPLL cells.

CONCLUSION

Cx43-mediated NFкB (p65) signal played an important role in mechanical stress-induced OPLL by transduction of mechanical signal, while giving rise to the activation of inflammatory response in ligament fibroblastsLevel of Evidence: N/A.

The Pathogenesis of Ossification of the Posterior Longitudinal Ligament

Ossification of the posterior longitudinal ligament (OPLL) is a multi-factorial disease involving an ectopic bone formation of spinal ligaments. It affects 0.8-3.0% aging Asian and 0.1-1.7% aging European Caucasian. The ossified ligament compresses nerve roots in the spinal cord and causes serious neurological problems such as myelopathy and radiculopathy. Research in understanding pathogenesis of OPLL over the past several decades have revealed many genetic and non-genetic factors contributing to the development and progress of OPLL. The characterizations of aberrant signaling of bone morphogenetic protein (BMP) and mitogen-activated protein kinases (MAPK), and the pathological phenotypes of OPLL-derived mesenchymal stem cells (MSCs) have provided new insights on the molecular mechanisms underlying OPLL. This paper reviews the recent progress in understanding the pathophysiology of OPLL and proposes future research directions on OPLL.

Network Cluster Analysis of Protein-Protein Interaction Network-Identified Biomarker for Type 2 Diabetes

Type 2 diabetes mellitus (T2DM) is a complex disease that is caused by an impairment in the secretion of β-cell insulin and by a peripheral resistance to insulin. Most patients suffering from T2DM and from obesity exhibit insulin resistance in the muscles, liver, and fat, resulting in a reduced response of these tissues to insulin. In healthy individuals, pancreatic islet β-cells secrete insulin to regulate the increase in blood glucose levels. Once these β-cells fail to function, T2DM develops. Despite the progress achieved in this field in recent years, the genetic causes for insulin resistance and for T2DM have not yet been fully discovered. The present study aims to characterize T2DM by comparing its gene expression with that of normal controls, as well as to identify biomarkers for early T2DM. Gene expression profiles were downloaded from the Gene Expression Omnibus, and differentially expressed genes (DEGs) were identified for type 2 diabetes. Furthermore, functional analyses were conducted for the gene ontology and for the pathway enrichment. In total, 781 DEGs were identified in the T2DM samples relative to healthy controls. These genes were found to be involved in several biological processes, including cell communication, cell proliferation, cell shape, and apoptosis. We constructed a protein-protein interaction (PPI) network, and the clusters in the PPI were analyzed by using ClusterONE. Six functional genes that may play important roles in the initiation of T2DM were identified within the network.