Association between gut microbiota and spinal stenosis: a two-sample mendelian randomization study.

Introduction: Considerable evidence has unveiled a potential correlation between gut microbiota and spinal degenerative diseases. However, only limited studies have reported the direct association between gut microbiota and spinal stenosis. Hence, in this study, we aimed to clarify this relationship using a two-sample mendelian randomization (MR) approach. Materials and Methods: Data for two-sample MR studies was collected and summarized from genome-wide association studies (GWAS) of gut microbiota (MiBioGen, n = 13, 266) and spinal stenosis (FinnGen Biobank, 9, 169 cases and 164, 682 controls). The inverse variance-weighted meta-analysis (IVW), complemented with weighted median, MR-Egger, weighted mode, and simple mode, was used to elucidate the causality between gut microbiota and spinal stenosis. In addition, we employed mendelian randomization pleiotropy residual sum and outlier (MR-PRESSO) and the MR-Egger intercept test to assess horizontal multiplicity. Cochran's Q test to evaluate heterogeneity, and "leave-one-out" sensitivity analysis to determine the reliability of causality. Finally, an inverse MR analysis was performed to assess the reverse causality. Results: The IVW results indicated that two gut microbial taxa, the genus Eubacterium fissicatena group and the genus Oxalobacter, have a potential causal relationship with spinal stenosis. Moreover, eight potential associations between genetic liability of the gut microbiota and spinal stenosis were implied. No significant heterogeneity of instrumental variables or horizontal pleiotropy were detected. In addition, "leave-one-out" sensitivity analysis confirmed the reliability of causality. Finally, the reverse MR analysis revealed that no proof to substantiate the discernible causative relationship between spinal stenosis and gut microbiota. Conclusion: This analysis demonstrated a possible causal relationship between certain particular gut microbiota and the occurrence of spinal stenosis. Further studies focused on the mechanism of gut microbiota-mediated spinal stenosis can lay the groundwork for targeted prevention, monitoring, and treatment of spinal stenosis.

Comparative Gene-Expression Analysis of the Ligamentum Flavum of Patients with Lumbar Spinal Canal Stenosis: Comparison between the Dural and Dorsal Sides of the Thickened Ligamentum Flavum.

Thickening of the ligamentum flavum is the main factor in the development of lumbar spinal canal stenosis (LSCS). Although previous studies have reported factors related to ligamentum flavum thickening, its etiology has not been clarified. Furthermore, it is often difficult to set proper controls to investigate the pathologies of thickening due to differences in patient characteristics, such as age, sex, obesity, and comorbidities. This study aimed to elucidate the pathologies of ligamentum flavum thickening by comparing the dural and dorsal sides of the thickened ligamentum flavum in patients with LSCS. Ligamentum flavum samples were collected from 19 patients with LSCS. The samples were divided into the dural and dorsal sides. The dural side was used as a control to assess the pathologies occurring on the dorsal side. Elastic Masson staining was used to assess the elastic fibres. Gene expression levels were comprehensively assessed using quantitative reverse transcription polymerase chain reaction and DNA microarray analyses. Gene ontology analysis was used to identify biological processes associated with differentially expressed genes. The elastic fibres were significantly decreased on the dorsal side of the thickened ligamentum flavum. Genes related to fibrosis, inflammation, tissue repair, remodeling, and chondrometaplasia, such as COL1A2, COL3A1, COL5A1, TGFB1, VEGFA, TNFA, MMP2, COL10A1, and ADAMTS4, were highly expressed on the dorsal side of the thickened ligamentum flavum. The biological processes occurring on the dorsal side of the thickened ligamentum flavum were extracellular matrix organization, cell adhesion, extracellular matrix disassembly, and proteolysis.These are considered important pathologies of ligamentum flavum thickening.

Surgically Treated Degenerative Lumbar Spine Diseases in Twins.

BACKGROUND: There is growing evidence to suggest a potential genetic component underlying the development and progression of lumbar spine diseases. However, the heritability and the concordance rates for the phenotypes requiring surgery for the common spine diseases lumbar spinal stenosis (LSS) and lumbar disc herniation (LDH) are unknown. The aim of this study was to determine the heritability and the concordance rates for LSS and LDH requiring surgery by studying monozygotic (MZ) and dizygotic (DZ) twin pairs. METHODS: Patients between 18 and 85 years of age who underwent surgery for LSS or LDH between 1996 and 2022 were identified in the national Swedish spine registry (LSS: 45,110 patients; LDH: 39,272 patients), and matched with the Swedish Twin Registry to identify MZ and DZ twins. Pairwise and probandwise concordance rates, heritability estimates, and MZ/DZ concordance ratios were calculated. RESULTS: We identified 414 twin pairs (92 MZ and 322 DZ pairs) of whom 1 or both twins underwent surgery for LSS. The corresponding number for LDH was 387 twin pairs (118 MZ and 269 DZ pairs). The probandwise concordance rate for LSS requiring surgery was 0.25 (26 of 105) (95% confidence interval [CI], 0.14 to 0.34) for MZ twins and 0.04 (12 of 328) (95% CI, 0.01 to 0.07) for DZ twins. The corresponding values for LDH requiring surgery were 0.03 (4 of 120) (95% CI, 0 to 0.08) and 0.01 (4 of 271) (95% CI, 0 to 0.04), respectively. The probandwise MZ/DZ concordance ratio was 6.8 (95% CI, 2.9 to 21.5) for LSS and 2.3 (95% CI, 0 to 8.9) for LDH. The heritability was significantly higher in LSS compared with LDH (0.64 [95% CI, 0.50 to 0.74] versus 0.19 [95% CI, 0.08 to 0.35]). CONCLUSIONS: Our findings suggest that genetic factors may play an important role in the risk of developing LSS requiring surgery, whereas heredity seems to be of less importance in LDH requiring surgery. LEVEL OF EVIDENCE: Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Causal relationships between anthropometric traits, bone mineral density, osteoarthritis and spinal stenosis: A Mendelian randomisation investigation.

OBJECTIVE: Spinal stenosis is a common condition among older individuals, with significant morbidity attached. Little is known about its risk factors but degenerative conditions, such as osteoarthritis (OA) have been identified for their mechanistic role. This study aims to explore causal relationships between anthropometric risk factors, OA, and spinal stenosis using Mendelian randomisation (MR) techniques. DESIGN: We applied two-sample MR to investigate the causal relationships between genetic liability for select risk factors and spinal stenosis. Next, we examined the genetic relationship between OA and spinal stenosis with linkage disequilibrium score regression and Causal Analysis Using Summary Effect estimates MR method. Finally, we used multivariable MR (MVMR) to explore whether OA and body mass index (BMI) mediate the causal pathways identified. RESULTS: Our analysis revealed strong evidence for the effect of higher BMI (odds ratio [OR] = 1.54, 95%CI: 1.41-1.69, p-value = 2.7 × 10-21), waist (OR = 1.43, 95%CI: 1.15-1.79, p-value = 1.5 × 10-3) and hip (OR = 1.50, 95%CI: 1.27-1.78, p-value = 3.3 × 10-6) circumference on spinal stenosis. Strong evidence of causality was also observed for higher bone mineral density (BMD): total body (OR = 1.21, 95%CI: 1.12-1.29, p-value = 1.6 × 10-7), femoral neck (OR = 1.35, 95%CI: 1.09-1.37, p-value = 7.5×10-7), and lumbar spine (OR = 1.38, 95%CI: 1.25-1.52, p-value = 4.4 × 10-11). We detected high genetic correlations between spinal stenosis and OA (rg range: 0.47-0.66), with Causal Analysis Using Summary Effect estimates results supporting a causal effect of OA on spinal stenosis (ORallOA = 1.6, 95%CI: 1.41-1.79). Direct effects of BMI, BMD on spinal stenosis remained after adjusting for OA in the MVMR. CONCLUSIONS: Genetic susceptibility to anthropometric risk factors, particularly higher BMI and BMD can increase the risk of spinal stenosis, independent of OA status. These results may inform preventative strategies and treatments.

Molecular and Genetic Mechanisms of Spinal Stenosis Formation: Systematic Review.

Spinal stenosis (SS) is a multifactorial polyetiological condition characterized by the narrowing of the spinal canal. This condition is a common source of pain among people over 50 years old. We perform a systematic review of molecular and genetic mechanisms that cause SS. The five main mechanisms of SS were found to be ossification of the posterior longitudinal ligament (OPLL), hypertrophy and ossification of the ligamentum flavum (HLF/OLF), facet joint (FJ) osteoarthritis, herniation of the intervertebral disc (IVD), and achondroplasia. FJ osteoarthritis, OPLL, and HLF/OLFLF/OLF have all been associated with an over-abundance of transforming growth factor beta and genes related to this phenomenon. OPLL has also been associated with increased bone morphogenetic protein 2. FJ osteoarthritis is additionally associated with Wnt/ß-catenin signaling and genes. IVD herniation is associated with collagen type I alpha 1 and 2 gene mutations and subsequent protein dysregulation. Finally, achondroplasia is associated with fibroblast growth factor receptor 3 gene mutations and fibroblast growth factor signaling. Although most publications lack data on a direct relationship between the mutation and SS formation, it is clear that genetics has a direct impact on the formation of any pathology, including SS. Further studies are necessary to understand the genetic and molecular changes associated with SS.

Integrative analysis of genome-wide DNA methylation and single-nucleotide polymorphism identified ACSM5 as a suppressor of lumbar ligamentum flavum hypertrophy.

BACKGROUND: Hypertrophy of ligamentum flavum (HLF) is a common lumbar degeneration disease (LDD) with typical symptoms of low back pain and limb numbness owing to an abnormal pressure on spinal nerves. Previous studies revealed HLF might be caused by fibrosis, inflammatory, and other bio-pathways. However, a global analysis of HLF is needed severely. METHODS: A genome-wide DNA methylation and single-nucleotide polymorphism analysis were performed from five LDD patients with HLF and five LDD patients without HLF. Comprehensive integrated analysis was performed using bioinformatics analysis and the validated experiments including Sanger sequencing, methylation-specific PCR, qPCR and ROC analysis. Furthermore, the function of novel genes in ligamentum flavum cells (LFCs) was detected to explore the molecular mechanism in HLF through knock down experiment, overexpression experiment, CCK8 assay, apoptosis assay, and so on. RESULTS: We identified 69 SNP genes and 735 661 differentially methylated sites that were enriched in extracellular matrix, inflammatory, and cell proliferation. A comprehensive analysis demonstrated key genes in regulating the development of HLF including ACSM5. Furthermore, the hypermethylation of ACSM5 that was mediated by DNMT1 led to downregulation of ACSM5 expression, promoted the proliferation and fibrosis, and inhibited the apoptosis of LFCs. CONCLUSION: This study revealed that DNMT1/ACSM5 signaling could enhance HLF properties in vitro as a potential therapeutic strategy for HLF.

Association between spinal stenosis and wild-type ATTR amyloidosis.

Age-related cardiac amyloidosis results from deposits of wild-type tranthyretin amyloid (ATTRwt) in cardiac tissue. ATTR may play a role in carpal tunnel syndrome (CTS) and in spinal stenosis (SS), indicating or presaging systemic amyloidosis. We investigated consecutive patients undergoing surgery for SS for ATTR deposition in the resected ligamentum flavum (LF) and concomitant risk of cardiac amyloidosis. Each surgical specimen (LF) was stained with Congo red, and if positive, the amyloid deposits were typed by mass spectrometry. Patients with positive specimens underwent standard of care evaluation with fat pad aspirates, serum and urine protein electrophoresis with immunofixation, free light-chain assay, TTR gene sequencing and technetium 99 m-pyrophosphate-scintigraphy. In 2018-2019, 324 patients underwent surgery for SS and 43 patients (13%) had ATTR in the LF with wild-type TTR gene sequences. Two cases of ATTRwt cardiac amyloidosis were diagnosed and received treatment. In this large series, ATTRwt was identified in 13% of the patients undergoing laminectomy for SS. Patients with amyloid in the ligamentum flavum were older and had a higher prevalence of CTS, suggesting a systemic form of ATTR amyloidosis involving connective tissue. Further prospective study of patients with SS at risk for systemic amyloidosis is warranted.

Genome-wide association studies of low back pain and lumbar spinal disorders using electronic health record data identify a locus associated with lumbar spinal stenosis.

ABSTRACT: Identifying genetic risk factors for lumbar spine disorders may lead to knowledge regarding underlying mechanisms and the development of new treatments. We conducted a genome-wide association study involving 100,811 participants with genotypes and longitudinal electronic health record data from the Electronic Medical Records and Genomics Network and Geisinger Health. Cases and controls were defined using validated algorithms and clinical diagnostic codes. Electronic health record-defined phenotypes included low back pain requiring healthcare utilization (LBP-HC), lumbosacral radicular syndrome (LSRS), and lumbar spinal stenosis (LSS). Genome-wide association study used logistic regression with additive genetic effects adjusting for age, sex, site-specific factors, and ancestry (principal components). A fixed-effect inverse-variance weighted meta-analysis was conducted. Genetic variants of genome-wide significance (P < 5 × 10-8) were carried forward for replication in an independent sample from UK Biobank. Phenotype prevalence was 48.8% for LBP-HC, 19.8% for LSRS, and 7.9% for LSS. No variants were significantly associated with LBP-HC. One locus was associated with LSRS (lead variant rs146153280:C>G, odds ratio [OR] = 1.17 for G, P = 2.1 × 10-9), but was not replicated. Another locus on chromosome 2 spanning GFPT1, NFU1, and AAK1 was associated with LSS (lead variant rs13427243:G>A, OR = 1.10 for A, P = 4.3 × 10-8) and replicated in UK Biobank (OR = 1.11, P = 5.4 × 10-5). This was the first genome-wide association study meta-analysis of lumbar spinal disorders using electronic health record data. We identified 2 novel associations with LSRS and LSS; the latter was replicated in an independent sample.

Circular RNA Expression Profile in Patients with Lumbar Spinal Stenosis Associated with Hypertrophied Ligamentum Flavum.

STUDY DESIGN: Sequencing and experimental analysis of the expression profile of circular RNAs (circRNAs) in hypertrophic ligamentum flavum (LFH). OBJECTIVES: The aim of this study was to identify differentially expressed circRNAs between LFH and nonhypertrophic ligamentum flavum tissues from lumbar spinal stenosis (LSS) patients. SUMMARY OF BACKGROUND DATA: Hypertrophy of the ligamentum flavum (LF) can cause LSS. circRNAs are important in various diseases. However, no circRNA expression patterns related to LF hypertrophy have been reported. METHODS: A total of 33 patients with LSS participated in this study. LF tissue samples were obtained when patients underwent decompressive laminectomy during surgery. The expression profile of circRNAs was analyzed by transcriptome high-throughput sequencing and validated with quantitative real-time polymerase chain reaction (PCR). Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses were performed for the differentially expressed circRNA-associated genes and related pathways. The connections between circRNAs and microRNAs were explored using Cytoscape. The role of hsa_circ_0052318 on LF cell fibrosis was assessed by analyzing the expression of collagen I and collagen III. RESULTS: The results showed that 2439 circRNAs of 4025 were differentially expressed between the LFH and nonhypertrophic ligamentum flavum tissues, including 1276 upregulated and 1163 downregulated circRNAs. The Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses revealed that these differentially expressed circRNAs functioned in biological processes, cellular components, and molecular functions. Autophagy and mammalian target of rapamycin were the top two signaling pathways affected by these circRNAs. Five circRNAs (hsa_circ_0021604, hsa_circ_0025489, hsa_circ_0002599, hsa_circ_0052318, and hsa_circ_0003609) were confirmed by quantitative real-time PCR. The network indicated a strong relationship between circRNAs and miRNAs. Furthermore, hsa_circ_0052318 overexpression decreased mRNA and protein expression of collagen I and III in LF cells from LFH tissues. CONCLUSION: This study identified circRNA expression profiles characteristic of hypertrophied LF in LSS patients, and demonstrated that hsa_circ_0052318 may play an important role in the pathogenesis of LF hypertrophy.Level of Evidence: N/A.

ADAM10 promotes the proliferation of ligamentum flavum cells by activating the PI3K/AKT pathway.

Ligamentum flavum hypertrophy (LFH) is an important cause of spinal canal stenosis and posterior longitudinal ligament ossification. Although a number of studies have focused on the mechanisms responsible for LFH, the cellular mechanisms remain poorly understood. The aim of the present study was to investigate the roles of differentially expressed genes (DEGs) in LFH, elucidate the mechanisms responsible for LFH and provide a potential therapeutic target for further studies. The GSE113212 dataset was downloaded from the Gene Expression Omnibus (GEO) database. The microarray data were analyzed and DEGs were obtained. Bioinformatics methods, such as Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment and protein­protein interaction (PPI) network analyses were used to obtain the key genes and signaling pathways. In addition, cells derived from hypertrophied ligamentum flavum were cultured, and the key genes and signaling pathways in ligamentum cells were identified through in vitro cell biology and molecular biology experiments. A total of 2,123 genes were screened as DEGs. Among these DEGs, 1,384 genes were upregulated and 739 genes were downregulated. The KEGG pathway analysis revealed that the DEGs were mainly enriched in the PI3K/AKT signaling pathway, and the PPI network analysis screened A disintegrin and metalloproteinase 10 (ADAM10) as a key gene. In vitro experimental verification revealed that ADAM10 promoted the proliferation of ligamentum flavum cells and led to the hypertrophy of the ligamentum by activating the PI3K/AKT pathway. On the whole, the in vitro experimental results suggested that ADAM10 promoted the proliferation of ligamentum flavum cells by activating the PI3K/AKT pathway, which may represent a pathogenic mechanism of LFH. The findings of the present study may provide a basis and direction for further studies on the cellular mechanisms of LFH and present a potential novel therapeutic target and clinical approach.

Congenital cervical spine malformation due to bi-allelic RIPPLY2 variants in spondylocostal dysostosis type 6.

RIPPLY2 is an essential part of the formation of somite patterning during embryogenesis and in establishment of rostro-caudal polarity. Here, we describe three individuals from two families with compound-heterozygous variants in RIPPLY2 (NM_001009994.2): c.238A > T, p.(Arg80*) and c.240-4 T > G, p.(?), in two 15 and 20-year-old sisters, and a homozygous nonsense variant, c.238A > T, p.(Arg80*), in an 8 year old boy. All patients had multiple vertebral body malformations in the cervical and thoracic region, small or absent rib involvement, myelopathies, and common clinical features of SCDO6 including scoliosis, mild facial asymmetry, spinal spasticity and hemivertebrae. The nonsense variant can be classified as likely pathogenic based on the ACMG criteria while the splice variants must be classified as a variant of unknown significance. With this report on two further families, we confirm RIPPLY2 as the gene for SCDO6 and broaden the phenotype by adding myelopathy with or without spinal canal stenosis and spinal spasticity to the symptom spectrum.

Pedigree analysis of lumbar developmental spinal stenosis: Determination of potential inheritance patterns.

Lumbar developmental spinal stenosis (DSS) refers to multilevel pre-existing narrowed spinal canals, which predispose to neural compromise. The objective of this study is to identify any inheritance pattern of DSS by utilizing pedigree charts. This was a case series of 13 families with a total of 80 subjects having magnetic resonance imaging (MRI) from L1 to S1. Cases (subjects with DSS) or controls (subjects without DSS) were identified by measuring their anteroposterior (AP) vertebral canal diameters. Multilevel model analyses were also performed to evaluate whether there is substantial clustering of observations within the families, and the effect of multilevel DSS. The intraclass correlation coefficient (ICC) and Akaike information criteria (AIC) were compared between models. Correlations between subject demographics and AP vertebral canal diameter were statistically insignificant at all levels. Only vertebral canal cross-sectional area, and axial and sagittal vertebral canal diameter were found to be statistically different between cases and controls at all levels (all p < .05). Both males and females were affected by DSS and there was no skipping of generation, which highly suggested DSS followed an autosomal dominant inheritance pattern. After accounting for multilevel DSS, there was a drop of more than 10 in AIC and some variances were also explained within families. This is the first study that suggests multilevel lumbar DSS to have an autosomal dominant inheritance pattern. Within families with a background of DSS, subjects had a smaller canal size, contributed by shortened axial and sagittal AP vertebral canal diameter, and smaller canal cross-sectional area.

Two GWAS-identified variants are associated with lumbar spinal stenosis and Gasdermin-C expression in Chinese population.

The aim of this study is to investigate the expression levels of genome-wide association studies (GWAS)-identified variants near Gasdermin-C (GSDMC) and its association with lumbar disc degeneration (LDD) in a Chinese population. In accordance with previously reported findings, our study involved the top 4 variants; rs6651255, rs7833174, rs4130415, and rs7816342. A total of 800 participants, 400 LDD patients and 400 controls were involved in the study. The LDD patients were divided into two mutually exclusive subgroups: subgroup 1: lumbar disc herniation; subgroup 2: lumbar spinal stenosis. Genotyping were performed using TaqMan assay, and Enzyme-Linked Immunosorbent Assay (ELISA) used to measure the plasma GSDMC levels, while quantitative reverse-transcription (qRT)-PCR and immunohistochemistry (IHC) were used to evaluate the GSDMC expression levels. Among the studied variants, there were no statistically significant differences in allelic and genotypic frequencies between LDD patients and their controls (all P > 0.05). However, the subgroup analysis revealed a significant association between rs6651255 and rs7833174 in patients with lumbar spinal stenosis (subgroup 2). Furthermore, the max-statistic test revealed that the inheritance models of two variants of lumbar spinal stenosis were represented by the recessive model. The plasma and mRNA expression levels of GSDMC were significantly higher in patients with lumbar spinal stenosis compared with the control group (P < 0.05). Furthermore, the CC genotypes of rs6651255 and rs7833174 were significantly associated with increased plasma expression levels of GSDMC in patients with lumbar spinal stenosis (P < 0.01). Two GWAS-identified variants (rs6651255 and rs7833174) near GSDMC were associated with a predisposition to lumbar spinal stenosis. GSDMC protein and mRNA expression levels may have prognostic qualities as biomarkers for the existence, occurrence or development of lumbar spinal stenosis.

Etiology of developmental spinal stenosis: A genome-wide association study.

Our study aimed to identify possible single nucleotide polymorphisms (SNPs) via a genome-wide association study (GWAS) approach and a candidate gene platform that were associated with lumbar developmental spinal stenosis (DSS). Southern Chinese population-based study volunteers were assessed (age range: 18-55 years). DSS was defined as the anteroposterior bony spinal canal diameter on T1-weighted axial MRI of L1 to S1. Genotyping was performed using the Illumina HumanOmniZhongHua-8 BeadChip. Using the canal diameter as the quantitative trait, genomic statistical analyses was performed. A total of 469 subjects were recruited. The mean axial AP measurements noted were: L1: 21.8 mm, L2: 21.9 mm, L3: 22.4 mm, L4: 20.2 mm, L5: 19.6 mm, and S1: 17.3 mm. Q-Q plots of genome-wide associations found significant differences in L4 and L5 measurements. More significant SNPs were found on chromosomes 8, 11, and 18. Low-density lipoprotein receptor-related protein 5 on chromosome 11 was found to be an important functional gene in canal bony development via candidate gene approach. We found two clusters in the findings with one including the upper levels (L1-L4) and the other the lower levels (L5 and S1). This is the first GWAS addressing DSS. The presence of multiple SNPs suggests a multi-factorial origin of DSS. Further analyses noted region-specific genetic predisposition, delineating distinct upper to lower lumbar regions of DSS. With better understanding of the DSS phenotype and genetic markers, the at-risk population can be identified early, preventative measures can be initiated, lifestyle/activity modification can be implemented, and more novel and precision-based therapeutics can be developed. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:1262-1268, 2018.

MiR-21 promotes fibrosis and hypertrophy of ligamentum flavum in lumbar spinal canal stenosis by activating IL-6 expression.

The molecular mechanism underlying the fibrosis of ligamentum flavum(LF) in patients with lumbar spinal canal stenosis(LSCS) remains unknown. MicroRNAs are reported to play important roles in regulating fibrosis in different organs. The present study aimed to identify fibrosis related miR-21 expression profile and investigate the pathological process of miR-21 in the fibrosis of LF hypertrophy and associated regulatory mechanisms. 15 patients with LSCS underwent surgical treatment were enrolled in this study. For the control group, 11 patients with lumbar disc herniation(LDH) was included. The LF thickness was measured on MRI. LF samples were obtained during the surgery. Fibrosis score was assessed by Masson's trichrome staining. The expression of miR-21 in LF tissues were determined by RT-PCR. Correlation among LF thickness, fibrosis score, and miR-21 expression was analyzed. In addition, Lentiviral vectors for miR-21 mimic were constructed and transfected into LF cells to examine the role of miR-21 in LF fibrosis. Types I and III collagen were used as indicators of fibrosis. IL-6 expression in LF cells after transfection was investigated by RT-PCR and ELISA. Patients in two groups showed similar outcomes regarding age, gender, level of LF tissue. The thickness and fibrosis score of LF in the LSCS group were significantly greater than those in LDH group (all P < 0.05). Similarly, the expression of miR-21 in LSCS group was substantially higher than that in LDH group(P < 0.05). Furthermore, the miR-21 expression exhibited positive correlations with the LF thickness (r = 0.595, P < 0.05) and fibrosis score (r = 0.608, P < 0.05). Of note, miR-21 over-expression increased the expression levels of collagen I and III (P < 0.05). Also, IL-6 expression and secretion in LF cells was elevated after transfection of miR-21 mimic. MiR-21 is a fibrosis-associated miRNA and promotes inflammation in LF tissue by activating IL-6 expression, leading to LF fibrosis and hypertrophy.

Expression of the JAK/STAT signaling pathway in the ligamentum flavum of patients with lumbar spinal canal stenosis.

BACKGROUND: Ligamentum flavum (LF) hypertrophy is an important cause of lumbar spinal canal stenosis (LSS), one of the most common spinal disorders in the elderly. Although many cytokines are reported to be associated with LF hypertrophy, the intracellular signaling system is rarely discussed. The purpose of this study was to identify the JAK/STAT signaling pathway and to examine the role of the JAK/STAT systems in the hypertrophied LF. METHODS: The LF of 10 LSS patients was analyzed and the expression of JAK1, STAT3, phosphorylated (p)-STAT3, and actin was examined by Western blot analysis. The expression of p-STAT3 was also examined by immunostaining and its positive cell ratio was compared between LSS and non-LSS samples. We measured the thickness of the LF on magnetic resonance images and studied the relationship between its thickness and the expression of p-STAT3. RESULTS: JAK1, STAT3, and p-STAT3 were detected in almost all samples by Western blot analysis. Immunoreactivity against p-STAT3 was observed mainly in endothelial- and fibroblast-like cells. The expression of p-STAT3 was significantly higher in LSS than non-LSS samples; it was significantly stronger on the dorsal than the dural side of the LF and positively correlated with the thickness of the LF on the dorsal side. CONCLUSIONS: The JAK/STAT signaling pathway is positively correlated with the thickness of the LF. Our findings suggest that JAK1 and STAT3 molecules are involved in and regulate LF hypertrophy.

Minimally Invasive Surgical Management of Thoracic Ossification of the Ligamentum Flavum Associated with X-linked Hypophosphatemia.

BACKGROUND: X-linked hypophosphatemia (XLH) is the most common inherited form of renal phosphate wasting and inherited rickets. Patients have hyperplasia of fibrochondrocytes in tendons and ligaments, causing the structures to thicken and calcify. Thickening of the lamina, hypertrophy of facet joints, and calcification of spinal ligaments are sequelae of this condition and can result in central or foraminal stenosis that compresses nerve roots or the spinal cord. We present a case of XLH with calcification of the ligamentum flavum in which the patient was operated on using minimally invasive posterior decompression. CASE DESCRIPTION: A 49-year-old man with a history of XLH presented to our emergency department with symptomatic myelopathy from multilevel thoracic stenosis. Radiographically, the calcified ligamentum flavum appeared to be the cause of the stenosis at various levels. The patient underwent a posterior decompression at the levels of compression, T4-T5, T8-T9, T9-T10, and T11-T12, via a minimally invasive spine surgery approach. Intraoperatively, the ligamentum flavum appeared to be both calcified and the source of spinal compression. Postoperatively, the patient experienced neurologic and radiographic improvement. CONCLUSION: Patients with a history of XLH and multilevel symptomatic spine stenosis can be treated successfully and safely with a minimally invasive posterior decompression.

A genealogical and clinical study of the phenotypical variation within the Swedish transthyretin His88Arg (p. His108Arg) amyloidosis family.

UNLABELLED: In 2005 we reported the first case of transthyretin His88Arg (p. His108Arg) amyloidosis, a mutation characterised by cardiomyopathy. Six additional gene carriers of whom five have clinical symptoms of disease have now been identified in Sweden, and we have been able to identify a possible founder and to characterise the Swedish phenotype of the transthyretin (TTR) His88Arg mutation. Genealogical studies of church records were used to identify the individuals with the disease and their families. Routine clinical investigations of neurological and heart manifestation of the disease were utilised. We found that genealogically all seven individuals were related and originated from the same region in Sweden. Amyloid deposits were demonstrated in biopsies and the TTR His88Arg mutation was identified in all patients. Patients had a late onset disease (≥ 50 years of age) and all exhibited a severe amyloid cardiomyopathy. A pronounced peripheral axonal neuropathy was with certainty demonstrated in one patient only, who also was operated for a magnetic resonance confirmed spinal stenosis, however, without any effect on his neurological symptoms. Five of the patients had carpal tunnel syndrome. The first reported case is now deceased from cardiac failure. One patient has had a sequential heart and liver transplantation. One gene carrier had no symptoms or findings of disease on latest evaluation at the age of 44. IN CONCLUSION: the Swedish TTRHis88Arg patients all have a common Swedish founder. Cardiomyopathy with heart failure, as well as carpal tunnel syndrome and spinal stenosis were early signs of disease; but peripheral neuropathy was present in one patient before symptoms of cardiomyopathy so the phenotypical presentation of this mutation is variable.

Lumbar spinal stenosis is a highly genetic condition partly mediated by disc degeneration.

Objective. Lumbar spinal stenosis is one of the most commonly diagnosed spinal disorders in older adults. Although the pathophysiology of the clinical syndrome is not well understood, a narrow central canal or intervertebral foramen is an essential or defining feature. The aim of the present study was to estimate the magnitude of genetic versus environmental influences on central lumbar spinal stenosis and to investigate disc degeneration and stature or bone development as possible genetic pathways.Methods. A classic twin study with multivariate analyses considering lumbar level and other covariates was conducted. The study sample comprised 598 male twins (147 monozygotic and 152 dizygotic pairs), 35-70 years of age, from the population-based Finnish Twin Cohort. The primary phenotypes were central lumbar stenosis as assessed qualitatively on magnetic resonance imaging (MRI) and quantitatively measured dural sac cross-sectional area. Additional phenotypes (to examine possible genetic pathways) included disc bulging and standing height, as an indicator of overall skeletal size or development.Results. The heritability estimate (h²) for qualitatively assessed central lumbar spinal stenosis on MRI was 66.9% (95% confidence interval [95% CI] 56.8,74.5). The broad-sense heritability estimate for dural sac cross-sectional area was 81.2% (95% CI 74.5, 86.1),with a similar magnitude of genetic influences across lumbar levels (h²=72.4­75.6). The additive genetic correlation of quantitatively assessed stenosis and disc bulging was extremely high. There was no indication of shared genetic influences between stenosis and stature.Conclusion. Central lumbar spinal stenosis and associated dural sac dimensions are highly genetic, and disc degeneration (bulging) appears to be one pathway through which genes influence spinal stenosis.

Progression of lumbar spinal stenosis is influenced by polymorphism of thrombospondin 2 gene in the Korean population.

PURPOSE: The aim of this study is to determine the contribution of thrombospondin 2 (THBS2) polymorphisms to the development and progression of lumbar spinal stenosis (LSS) in the Korean population. METHODS: We studied 148 symptomatic patients with radiographically proven LSS and 157 volunteers with no history of back problems from our institution. Magnetic resonance images were obtained for all the patients and controls. Quantitative image evaluation for LSS was performed to evaluate the severity of LSS. All patients and controls were genotyped for THBS2 allele variations using a polymerase chain reaction-based technique. RESULTS: We found no causal single nucleotide polymorphism (SNPs) in THBS2 that were significantly associated with LSS. Two SNPs (rs6422747, rs6422748) were over-represented in controls [P = 0.042, odds ratio [OR] = 0.55 and P = 0.042, OR = 0.55, respectively]. Haplotype analysis showed that the ''AGAGACG'' haplotype (HAP4) and ''AAGGACG'' haplotype (HAP5) were over-represented in severe LSS patients (P = 0.0147, OR = 2.02 and P = 0.0137, OR = 2.48, respectively). In addition, the ''AAAGGGG'' haplotype (HAP1) was over-represented in controls (P = 0.0068, OR = 0.30). CONCLUSIONS: Although no SNPs in THBS2 were associated with LSS, haplotypes (HAP4 and HAP5) were significantly associated with progression of LSS in the Korean population, whereas another haplotype (HAP1) may play a protective role against LSS development.