Identification and bioinformatics analysis of lncRNAs in serum of patients with ankylosing spondylitis.

OBJECTIVES: The aim of this study was to explore the long non-coding RNA (lncRNA) expression profiles in serum of patients with ankylosing spondylitis (AS). The role of these lncRNAs in this complex autoimmune situation needs to be evaluated. METHODS: We used high-throughput whole-transcriptome sequencing to generate sequencing data from three patients with AS and three normal controls (NC). Then, we performed bioinformatics analyses to identify the functional and biological processes associated with differentially expressed lncRNAs (DElncRNAs). We confirmed the validity of our RNA-seq data by assessing the expression of eight lncRNAs via quantitative reverse transcription polymerase chain reaction (qRT-PCR) in 20 AS and 20 NC samples. We measured the correlation between the expression levels of lncRNAs and patient clinical index values using the Spearman correlation test. RESULTS: We identified 72 significantly upregulated and 73 significantly downregulated lncRNAs in AS patients compared to NC. qRT-PCR was performed to validate the expression of selected DElncRNAs; the results demonstrated that the expression levels of MALAT1:24, NBR2:9, lnc-DLK1-35:13, lnc-LARP1-1:1, lnc-AIPL1-1:7, and lnc-SLC12A7-1:16 were consistent with the sequencing analysis results. Enrichment analysis showed that DElncRNAs mainly participated in the immune and inflammatory responses pathways, such as regulation of protein ubiquitination, major histocompatibility complex class I-mediated antigen processing and presentation, MAPkinase activation, and interleukin-17 signaling pathways. In addition, a competing endogenous RNA network was constructed to determine the interaction among the lncRNAs, microRNAs, and mRNAs based on the confirmed lncRNAs (MALAT1:24 and NBR2:9). We further found the expression of MALAT1:24 and NBR2:9 to be positively correlated with disease severity. CONCLUSION: Taken together, our study presents a comprehensive overview of lncRNAs in the serum of AS patients, thereby contributing novel perspectives on the underlying pathogenic mechanisms of this condition. In addition, our study predicted MALAT1 has the potential to be deeply involved in the pathogenesis of AS.

RNA sequencing and bioinformatics analysis of differentially expressed genes in the peripheral serum of ankylosing spondylitis patients.

BACKGROUND: Ankylosing spondylitis (AS) is a chronic progressive autoimmune disease characterized by spinal and sacroiliac arthritis, but its pathogenesis and genetic basis are largely unclear. METHODS: We randomly selected three serum samples each from an AS and a normal control (NC) group for high-throughput sequencing followed by using edgeR to find differentially expressed genes (DEGs). Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes, Reactome pathway analyses, and Gene Set Enrichment Analysis were used to comprehensively analyze the possible functions and pathways involved with these DEGs. Protein-protein interaction (PPI) networks were constructed using the STRING database and Cytoscape. The modules and hub genes of these DEGs were identified using MCODE and CytoHubba plugins. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was used to validate the expression levels of candidate genes in serum samples from AS patients and healthy controls. RESULTS: We successfully identified 100 significant DEGs in serum. When we compared them with the NC group, 49 of these genes were upregulated in AS patients and 51 were downregulated. GO function and pathway enrichment analysis indicated that these DEGs were mainly enriched in several signaling pathways associated with endoplasmic reticulum stress, including protein processing in the endoplasmic reticulum, unfolded protein response, and ubiquitin-mediated proteolysis. We also constructed a PPI network and identified the highly connected top 10 hub genes. The expression levels of the candidate hub genes PPARG, MDM2, DNA2, STUB1, UBTF, and SLC25A37 were then validated by RT-qPCR analysis. Finally, receiver operating characteristic curve analysis suggested that PPARG and MDM2 may be the potential biomarkers of AS. CONCLUSIONS: These findings may help to further elucidate the pathogenesis of AS and provide valuable potential gene biomarkers or targets for the diagnosis and treatment of AS.

Profiling and Bioinformatics Analysis of Differentially Expressed circRNAs in Spinal Ligament Tissues of Patients with Ankylosing Spondylitis.

Recent studies have reported that circular RNAs (circRNAs) play a crucial regulatory role in a variety of human diseases. However, the roles of circRNAs in ankylosing spondylitis (AS) remain unclear. In this study, we conducted circRNA expression profiling of the spinal ligament tissues of patients with AS by RNA sequencing (RNA-seq) and analyzed the potential functions of differentially expressed circRNA by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses to investigate the potential mechanisms associated with AS. The results showed that a total of 1,172 circRNAs were detected in the spinal ligament tissue samples, of which 123 circRNAs were significantly differentially expressed by a fold change ≥ 1.5 and p value < 0.05. Among these, 57 circRNAs were upregulated, and 66 were downregulated. GO and KEGG analyses demonstrated that the differentially expressed circRNAs were mainly involved in the regulation of biological processes of peptidyl-serine phosphorylation and human immune system that may be related to AS. In addition, the circRNA/miRNA interaction networks were established to predict the potential roles of differentially expressed circRNAs by bioinformatics analysis. Taken together, these results revealed the expression profiles of circRNAs and the potential functions of the differentially expressed circRNAs in the spinal ligament tissue of patients with AS, which may provide new clues for understanding the mechanisms associated with AS, and proceed to identify novel potential molecular targets for the diagnoses and treatment of AS.

A posterior-only approach for ankylosing spondylitis (AS) with thoracolumbar pseudoarthrosis: a clinical retrospective study.

BACKGROUND: Surgical treatment has been recommended by most surgeons to treat pseudarthrosis in ankylosing spondylitis (AS). However, there is still some debate on the necessity of anterior fusion. There is very limited literature on the treatment and surgical outcomes of thoracolumbar pseudarthrosis in AS patients treated through a posterior-only approach. METHODS: From January 1, 2012 to December 31, 2017, a total of 42 cases diagnosed with thoracolumbar pseudarthrosis in AS patients with moderate kyphosis were included in this study. All of the patients received posterior-only kyphosis correction, internal fixation and fusion without anterior fusion, and underwent at least 2 years of follow-up. Clinical and radiographic results and complications were assessed. RESULTS: All of the patients were followed up for an average of 35.3 months (range, 24-48 months), and they achieved successful bone graft fusion at the pseudarthrosis sites. Satisfactory radiographic changes were achieved in these patients. The Cobb angles of global kyphosis (GK) were corrected from 53.2 ± 5.4 degrees preoperatively to 33.2 ± 4.3 degrees postoperatively, and to 36.1 ± 5.3 degrees at the latest follow-up. The Cobb angles of local kyphosis (LK) were corrected from 43.3 ± 4.6 degrees preoperatively to 26.8 ± 3.3 degrees postoperatively, and to 28.2 ± 3.6 degrees at the latest follow-up. The mean sagittal vertical axis (SVA) were corrected from 7.6 ± 4.2 cm preoperatively to 4.3 ± 2.1 cm postoperatively, and to 4.8 ± 2.3 cm at the latest follow-up. No serious neurological complication or deep wound infection was found in these 42 patients. CONCLUSION: Posterior-only kyphosis correction and fixation without anterior fusion can achieve excellent bone fusion and satisfactory improvement in AS patients with thoracolumbar pseudarthrosis. This method may be a good choice for treating thoracolumbar pseudarthrosis in AS patients with moderate kyphosis.

Repair mechanism of astrocytes and non-astrocytes in spinal cord injury.

BACKGROUND: Spinal cord injury (SCI) is a destructive disease that incurs huge personal and social costs, and there is no effective treatment. Although the pathogenesis and treatment mechanism of SCI has always been a strong scientific focus, the pathogenesis of SCI is still under investigation. AIM: To determine the key genes based on the modularization of in-depth analysis, in order to identify the repair mechanism of astrocytes and non-astrocytes in SCI. METHODS: Firstly, the differences between injured and non-injured spinal cord of astrocyte (HA), injured and non-injured spinal cord of non-astrocyte (FLOW), injured spinal cord of non-injured astrocyte (HA) and non-injured spinal cord of non-astrocyte (FLOW), and non-injured spinal cord of astrocyte (HA) and non-astrocyte (FLOW) were analyzed. The total number of differentially expressed genes was obtained by merging the four groups of differential results. Secondly, the genes were co-expressed and clustered. Then, the enrichment of GO function and KEGG pathway of module genes was analyzed. Finally, non-coding RNA, transcription factors and drugs that regulate module genes were predicted using hypergeometric tests. RESULTS: In summary, we obtained 19 expression modules involving 5216 differentially expressed genes. Among them, miR-494, XIST and other genes were differentially expressed in SCI patients, and played an active regulatory role in dysfunction module, and these genes were recognized as the driving genes of SCI. Enrichment results showed that module genes were significantly involved in the biological processes of inflammation, oxidation and apoptosis. Signal pathways such as NF-kappa B/A20, AMPK and MAPK were significantly regulated. In addition, non-coding RNA pivot (including miR-136-5p and let-7d-5p, etc.) and transcription factor pivot (including NFKB1, MYC, etc.) were identified as significant regulatory dysfunction modules. CONCLUSION: Overall, this study uncovered a co-expression network of key genes involved in astrocyte and non-astrocyte regulation in SCI. These findings helped to reveal the core dysfunction modules, potential regulatory factors and driving genes of the disease, and to improve our understanding of its pathogenesis.

MicroRNA-218-5p relieves postmenopausal osteoporosis through promoting the osteoblast differentiation of bone marrow mesenchymal stem cells.

MicroRNAs (miRs) are short noncoding RNAs that play key regulatory roles in osteoblast differentiation. In this study, the specific regulatory roles of miR-218-5p on postmenopausal osteoporosis (PMOP) were investigated. The mouse model of PMOP was established by bilateral ovariectomy, and the injection of miR-218-5p mimics significantly relieved PMOP degree. Then, bone marrow mesenchymal stem cells (BMMSCs) isolated from PMOP mice were induced into osteoblasts. When compared with normal BMMSCs, PMOP BMMSCs exhibited significantly lower alkaline phosphatase (ALP) activity and less mineralized nodules, as well as downregulated miR-218-5p, Runx2, Osterix, COL1A1, and OCN after induction (P < .05). The transfection of miR-218-5p mimics, and inhibitor significantly promoted, inhibited the osteoblast differentiation of PMOP BMMSCs, respectively. In addition, COL1A1 was a target of miR-218-5p. The transfection of miR-218-5p mimics into PMOP BMMSCs significantly upregulated COL1A1 at 14th and 21st day post-induction, but not at 7th day. Our findings suggest miR-218-5p may relieve PMOP through promoting the osteoblast differentiation of BMMSCs.

The renin-angiotensin system in the synovium promotes periarticular osteopenia in a rat model of collagen-induced arthritis.

Periarticular osteopenia is the most specific hallmark of rheumatoid arthritis (RA). The renin-angiotensin system (RAS) in the synovium has been found to participate in the pathogenic process of RA. This study examined whether and how RAS regulates periarticular osteopenia in RA. The synovial tissues from patients with RA and osteoarthritis (OA) were prepared. Female Sprague-Dawley rats were treated with either saline, bovine type II collagen (CII) to induce arthritis (CIA), or CII combined with perindopril, an inhibitor of angiotensin-converting enzyme (ACE). Expressions of RAS components, including AT1R, AT2R and ACE, in human and rat synovial tissues were detected. Bone mass of rat joints was examined. Levels of RANKL, OPG and DKK-1 in rat synovium and expressions of TRAF6 and ß-catenin in rat bone were examined. The results showed that AT1R, AT2R and ACE in human and rat synovium were up-regulated, but the increased ACE in rat synovial tissues was abrogated by perindopril. While CIA rats displayed increased bone resorption and decreased bone formation, perindopril treatment almost completely abrogated the RAS-mediated osteopenia, indicating that inhibition of ACE reduced the joint damages in rats. The expressions of RANKL and DKK-1 increased in CIA rats as compared with those in the control; TRAF6 was up-regulated and ß-catenin was down-regulated in the bone tissues of CIA rats. The changes were then reversed by the use of perindopril. Our findings demonstrate that RAS in the synovium promotes periarticular osteopenia by increasing bone resorption and decreasing bone formation through modulating the RANKL/RANK/TRAF6 and Wnt/ß-catenin pathways.

Surgical strategies for thoracic myelopathy due to ossification of ligamentum flavum: A technical note based on radiological type.

AIM: Ossification of the ligamentumflavum (OLF) is a primary cause of thoracic myelopathy. A relatively safe surgical technique based on radiological type is described for the OLF-induced thoracic myelopathy. MATERIAL AND METHODS: Forty patients with thoracic myelopathy caused by OLF were studied retrospectively. The OLF was divided into fused and non-fused types according to the CT and MRI findings. All patients underwent posterior decompression. For the fused type, open-door laminectomy and for the non-fused type, French-door laminectomy surgical techniques were adopted. Pre-operation, post-operative, and follow-up neurological status were evaluated using the modified Japanese Orthopaedic Association (mJOA) score. RESULTS: The mean duration of symptoms was 9.2±11.5 and 8.4±9.7months in the non-fused and fused groups, respectively. The apex of OLF at the most severely compressed level was located at 2.7±1.9mm above the disc level: 2.4±1.6 and 3.0±2.2mm in the non-fused and fused groups, respectively. The preoperative mJOA scores were 5.0±1.1 and 4.2±0.9 in the non-fused and fused groups, respectively. After the operation, the neurological deficits in all patients improved. With an average follow-up of 33.9 months, the mJOA score ultimately improved in both groups. CONCLUSION: In OLF-induced thoracic myelopathy, the en bloc elevation of the laminae with the OLF plaque is emphasized at the key site for surgical decompression. Based on the present classification of OLF, different surgical strategies should be adopted for a safe neurological decompression.

MiR-9 promotes osteoblast differentiation of mesenchymal stem cells by inhibiting DKK1 gene expression.

The aim of this study is to investigate the role of miR-9 and its mechanism on the osteoblast differentiation of mesenchymal stem cells. Real-time PCR and western blotting were used to study gene expression. Assay of Alkaline phosphatase activity and alizarin red staining were used to examine osteoblast differentiation. Transfection of miR-9 mimics or lent-shmiR-9 was used to modulate the level of miR-9 in C2C12. Overexpression of miR-9 in C2C12 cells stimulated alkaline phosphatase activity and osteoblast mineralization, as well as the expression of osteoblast marker genes Col I, Ocn and Bsp. Gene silencing of miR-9 in C2C12 resulted in the suppression of alkaline phosphatase activity and osteoblast mineralization, as well as the expression of Col I, Ocn and Bsp. DKK1 mRNA was not affected by miR-9 overexpression, however, DKK1 protein was significantly decreased. Moreover, DKK1 3'-UTR mediated transcriptional luciferase activity was also significantly suppressed by miR-9 overexpression. DKK1 mRNA was not affected by miR-9 gene silencing, however, DKK1 protein was significantly stimulated. Moreover, DKK1 3'-UTR mediated transcriptional luciferase activity was significantly stimulated by miR-9 gene silencing, and suppressed by miR-9 overexpression, however, DKK1 3'-UTR mutant mediated luciferase activity was unaffected. The siRNA derived gene silencing of DKK1 blocked the inhibiting effect of shmiR-9 on the expression of alkaline phosphatase; and blocked the inhibiting effect of shmiR-9 on the expression of ColI, Ocn and Bsp. MiR-9 promotes osteoblast differentiation of mesenchymal cell C2C12 by suppressing the gene expression of DKK1.

Role of reactive oxygen species in angiotensin II: induced receptor activator of nuclear factor-κB ligand expression in mouse osteoblastic cells.

Angiotensin II (Ang II) has been shown to induce receptor activator of nuclear factor-κB ligand (RANKL) expression in osteoblasts associated with its effect on reactive oxygen species (ROS) production. The objective of the present study was to investigate the potential pathways by which Ang II induces RANKL expression and the role of ROS in Ang II-induced RANKL expression in mouse osteoblastic MC3T3-E1 cells. Treatment with Ang IIinduced RANKL expression in a dose- and time-dependent manner in osteoblasts, which was attenuated by pre-treatment with an AT1 receptor antagonist (olmesartan), ROS scavenger (N-acetylcysteine, NAC), or the ERK inhibitor (U0126), but not with AT2R antagonist (PD123319). Furthermore, Ang II enhanced AT1R and NAD(P)H oxidase (NOX) p22(phox) and p67(phox) expression and activity in osteoblasts. In addition, Ang II promoted ROS production, which was mitigated by pre-treatment with olmesartan or a NOX inhibitor (diphenyleneiodonium, DPI), but not with PD1123319 or U0126, in osteoblasts. Moreover, Ang II enhanced the ERK1/2 phosphorylation, which was abrogated by pre-treatment with olmesartan, NAC, DPI, or U0126 in osteoblasts. These results suggest that Ang II, through its AT1R, enhanced NOX activity and ROS production, and activated the ERK pathway to up-regulate RANKL expression in osteoblasts in vitro.