The genetics of intervertebral disc degeneration.Associated genes

A Comprehensive Review of Genetic Variations in Collagen-Encoding Genes and Their Implications in Intervertebral Disc Degeneration

This comprehensive review examines the intricate relationship between genetic variations in collagen-encoding genes and their implications in intervertebral disc degeneration (IVDD). Intervertebral disc degeneration is a prevalent spinal condition characterized by structural and functional changes in intervertebral discs (IVDs), and understanding its genetic underpinnings is crucial for advancing diagnostic and therapeutic strategies. The review begins by exploring the background and importance of collagen in IVDs, emphasizing its role in providing structural integrity. It then delves into the significance of genetic variations within collagen-encoding genes, categorizing and discussing their potential impact on disc health. The methods employed in studying these variations, such as genome-wide association studies (GWASs) and next-generation sequencing (NGS), are also reviewed. The subsequent sections analyze existing literature to establish associations between genetic variations and IVDD, unraveling molecular mechanisms linking genetic factors to disc degeneration. The review concludes with a summary of key findings, implications for future research and clinical practice, and a reflection on the importance of understanding genetic variations in collagen-encoding genes to diagnose and treat IVDD. The insights gleaned from this review contribute to our understanding of IVDD and hold promise for the development of personalized interventions based on individual genetic profiles.

MMP3 single-nucleotide polymorphisms are associated with noncontact ACL injuries in competing high-level athletes

Matrix metalloproteinases (MMPs) play an important role in matrix remodeling, as well as in ligament integrity. Anterior cruciate ligament (ACL) rupture is a severe and frequent knee injury in sports. The aim of this study was to investigate polymorphisms within the MMP3 gene with the predisposition for noncontact ACL rupture in the Croatian professional athletes. One hundred eighty-seven (95 with ACL rupture occurring through a noncontact mechanism and 92 asymptomatic controls) unrelated Caucasians were recruited between 2016 and 2017. All participants were genotyped for three single-nucleotide polymorphisms (SNP) within the MMP3 gene: rs591058 C/T, rs650108 A/G, and rs679620 G/A using the pyrosequencing method. For all three investigated SNPs, genotype frequencies have significantly differed between cases and controls. The MMP3 rs591058 TT (p = 0.0012, odds ratio [OR] = 38.541, 95% confidence interval [CI] = 1.7024-8.7254), rs650108 GG (p = 0.0051, OR = 23.338, 95% CI = 1.2899-4.2226) and rs679620 AA (p = 0.0030, OR = 34.750, 95% CI = 1.5266-7.9101) genotypes, as well as haplotype variant T-G-A (p = 0.0104, OR = 1.71, 95% CI = 1.13-2.59) were significantly overrepresented in cases compared to controls. These results support association between functional variants within the MMP3 gene and the risk of ACL rupture. Still, further research is needed to corroborate these results in a larger population.

Epidemiology of Lumbar Degenerative Phenotypes of Children and Adolescents: A Large-Scale Imaging Study

STUDY DESIGN

Cross-sectional study.

OBJECTIVE

Recently, there has been a rise in children and adolescents developing low back pain and/or sciatica. Degenerative lumbar spine MRI phenotypes can occur in this population but reports have been sporadic and the true incidence of such spine changes remains debatable. As such, the study aimed to address the epidemiology of MRI phenotypes of the lumbar spine in this young population.

METHODS

597 children and adolescents with lumbar MRIs were included in the study. T1- and T2-weighted lumbar images from L1/2 to L5/S1 were analyzed in axial and sagittal planes. Global phenotype assessment was performed of each level and based on established nomenclature protocols.

RESULTS

The cohort consisted of 57.3% (342) boys and 42.7% (255) girls, with a mean age of 10.75 ± 5.25 years (range: 0 to 18 years). The prevalence of imaging findings of lumbar disc degeneration (LDD) and lumbar disc herniation (LDH) were 2.2% (95% CI: 0.93-3.43) and 5.8% (95%CI: 2.58-8.99), respectively. There was significant difference between each disc segment from L1/2 to L5/S1 for both LDD and LDH. Schmorl's nodes were noted in 16 cases (2.7%, youngest case as 15 years), with 11 boys (68.8%) and most frequent segment as L3/4. Modic changes and high-intensity zones were absent in this cohort.

CONCLUSIONS

LDD can emerge as early as the first decade of life with Schmorl's nodes, without additional specific phenotypes, including Modic changes and high-intensity zones. The study provides valuable information of a unique age group that is often under-represented but equally important as adults.

Intervertebral disc degeneration and osteoarthritis: a common molecular disease spectrum

Intervertebral disc degeneration (IDD) and osteoarthritis (OA) affecting the facet joint of the spine are biomechanically interdependent, typically occur in tandem, and have considerable epidemiological and pathophysiological overlap. Historically, the distinctions between these degenerative diseases have been emphasized. Therefore, research in the two fields often occurs independently without adequate consideration of the co-dependence of the two sites, which reside within the same functional spinal unit. Emerging evidence from animal models of spine degeneration highlight the interdependence of IDD and facet joint OA, warranting a review of the parallels between these two degenerative phenomena for the benefit of both clinicians and research scientists. This Review discusses the pathophysiological aspects of IDD and OA, with an emphasis on tissue, cellular and molecular pathways of degeneration. Although the intervertebral disc and synovial facet joint are biologically distinct structures that are amenable to reductive scientific consideration, substantial overlap exists between the molecular pathways and processes of degeneration (including cartilage destruction, extracellular matrix degeneration and osteophyte formation) that occur at these sites. Thus, researchers, clinicians, advocates and policy-makers should consider viewing the burden and management of spinal degeneration holistically as part of the OA disease continuum.

Risk factors for lumbar disc herniation in adolescents and young adults: A case-control study

Background

There is a limited understanding of the risk factors for lumbar disc herniation (LDH) in younger people, even though the evidence suggests that LDH is more prevalent in this population. This study aimed to comprehensively analyze the risk factors for LDH in adolescents and young adults.

Methods

The medical records of all patients were retrospectively reviewed with inclusion criteria of being younger than 25 years. Magnetic resonance imaging (MRI) was used to confirm LDH from September 2016 to September 2021. Furthermore, 104 healthy people in the same age range were enrolled as the control group from physical examination centers. Gender, BMI, smoking, drinking, genetic history, sitting posture, daily sitting time, traumatic history of the lower back, scoliosis, and daily exercise time were examined for all enrolled people. These factors were statistically analyzed to determine the high-risk factors.

Results

A total of 208 young individuals were enrolled in the present study. The mean age of the study group and the control group was 21.06 ± 3.27 years (range: 11-25 years) and 21.26 ± 2.23 years (range: 15-25 years), respectively. The result of the chi-squared test demonstrated that there was a significant difference in BMI of more than 30 (p < 0.001), genetic history (p = 0.004), sitting posture (p < 0.001), daily sitting time of more than 6 h (p < 0.001), and the history of low back trauma (p = 0.002). Additionally, multivariate logistic regression showed that these were high-risk factors for LDH, particularly the duration of daily sitting time (more than 6 h).

Conclusions

BMI of more than 30, genetic history, sitting posture, daily sitting time of more than 6 h, and a history of low back trauma are the high-risk factors for adolescents and young adults with LDH. Therefore, providing them with the proper guidance and education, particularly about the protection of the lower back and the reduction of spinal load, could play a key role in preventing and reducing LDH.

Risk Factors for Adjacent Segment Disease Following Anterior Cervical Discectomy and Fusion with Plate Fixation: A Systematic Review and Meta-Analysis

BACKGROUND

Adjacent segment disease (ASD) following anterior cervical discectomy and fusion with plating (ACDF-P) may yield a poor prognosis or reoperation. This review aimed to summarize risk factors for radiographic ASD (RASD) and clinical ASD (CASD) after ACDF-P.

METHODS

Six electronic databases were searched from inception to October 30, 2021. Four reviewers independently screened titles, abstracts, and full-text articles to identify relevant studies. Methodological quality of the included studies was evaluated. Meta-analyses for risk factors were conducted, if possible.

RESULTS

Sixteen cohort and 3 case-control studies (3,563 participants) were included. These studies showed low (n = 2), moderate (n = 9), and high (n = 8) risk of bias. One risk factor for RASD was pooled for 2 meta-analyses based on the follow-up period. Four different risk factors for CASD at ≥4 years were pooled for meta-analyses. Limited evidence showed that multi-level fusion, greater asymmetry in total or functional cross-sectional area of the cervical paraspinal muscle, and preoperative degeneration in a greater number of segments were associated with a higher RASD incidence <4 years after ACDF-P. In contrast, no significant risk factors were identified for CASD <4 years after ACDF-P. At ≥4 years after ACDF-P, limited evidence supported that both cephalad and caudal plate-to-disc distances of <5 mm were associated with a higher RASD incidence, and very limited evidence supported that developmental canal stenosis, preoperative RASD, unfused C5-C6 or C6-C7 adjacent segments, use of autogenous bone graft, and spondylosis-related ACDF-P were associated with a higher CASD incidence.

CONCLUSIONS

Although several risk factors for RASD and CASD development after ACDF-P were identified, the supporting evidence was very limited to limited. Future prospective studies should extend the existing knowledge by more robustly identifying risk factors for RASD and CASD after ACDF-P to inform clinical practice.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Degenerative Disc Disease of the Spine: From Anatomy to Pathophysiology and Radiological Appearance, with Morphological and Functional Considerations

Degenerative disc disease is a common manifestation in routine imaging of the spine; this finding is partly attributable to physiological aging and partly to a pathological condition, and sometimes this distinction is simply not clear. In this review, we start focusing on disc anatomy and pathophysiology and try to correlate them with radiological aspects. Furthermore, there is a special focus on degenerative disc disease terminology, and, finally, some considerations regarding disc morphology and its specific function, as well as the way in which these aspects change in degenerative disease. Radiologists, clinicians and spine surgeons should be familiar with these aspects since they have an impact on everyday clinical practice.

Effects of Sex and Obesity on LEP Variant and Leptin Level Associations in Intervertebral Disc Degeneration

Intervertebral disc degeneration (IVDD), for which obesity and genetics are known risk factors, is a chronic process that alters the structure and function of the intervertebral discs (IVD). Circulating leptin is positively correlated with body weight and is often measured to elucidate the pathogenesis of IVD degeneration. In this study, we examined the associations of LEP single nucleotide polymorphisms (SNPs) genetic and environmental effects with IVDD. A total of 303 Taiwanese patients with IVDD (mean age, 58.6 ± 12.7 years) undergoing cervical discectomy for neck pain or lumbar discectomy for back pain were enrolled. Commercially available enzyme-linked immunosorbent assay (ELISA) kits measured the circulating plasma leptin levels. TaqMan SNP genotyping assays genotyped the LEP SNPs rs2167270 and rs7799039. Leptin levels were significantly increased in obese individuals (p < 0.001) and non-obese or obese women (p < 0.001). In the dominant model, recoded minor alleles of rs2167270 and rs7799039 were associated with higher leptin levels in all individuals (p = 0.011, p = 0.012). Further, the association between these LEP SNPs and leptin levels was significant only in obese women (p = 0.025 and p = 0.008, respectively). There was an interaction effect between sex and obesity, particularly among obese women (interaction p = 0.04 and 0.02, respectively). Our findings demonstrate that these SNPs have sex-specific associations with BMI in IVDD patients, and that obesity and sex, particularly among obese women, may modify the LEP transcription effect.

Targeting Autophagy for Developing New Therapeutic Strategy in Intervertebral Disc Degeneration

Intervertebral disc degeneration (IVDD) is a prevalent cause of low back pain. IVDD is characterized by abnormal expression of extracellular matrix components such as collagen and aggrecan. In addition, it results in dysfunctional growth, senescence, and death of intervertebral cells. The biological pathways involved in the development and progression of IVDD are not fully understood. Therefore, a better understanding of the molecular mechanisms underlying IVDD could aid in the development of strategies for prevention and treatment. Autophagy is a cellular process that removes damaged proteins and dysfunctional organelles, and its dysfunction is linked to a variety of diseases, including IVDD and osteoarthritis. In this review, we describe recent research findings on the role of autophagy in IVDD pathogenesis and highlight autophagy-targeting molecules which can be exploited to treat IVDD. Many studies exhibit that autophagy protects against and postpones disc degeneration. Further research is needed to determine whether autophagy is required for cell integrity in intervertebral discs and to establish autophagy as a viable therapeutic target for IVDD.

A Case-control Study of Major Genetic Predisposition Risk Alleles in Developing DDD in the Northeast US Population: Effects of Gene-gene Interactions

STUDY DESIGN

A case-control study of risk alleles for degenerative disc disease (DDD) using magnetic resonance (MR) imaging for phenotyping.

OBJECTIVE

We aim to provide the first statistically adequately powered study of the relationship between the presence of common risk alleles and occurrence of DDD in Eastern US population.

SUMMARY OF BACKGROUND DATA

Many genetic predisposing factors have been identified in elevating the risk of DDD, including common variants in VDR, COL1A1, AGC1, COL9A2/3 genes.

METHODS

We utilized the Mass General Brigham (MGB) Biobank in which subjects' Medical Record is linked with genotyped data from single-nucleotide polymorphism (SNP) arrays. Subjects with lumbosacral spine MR imaging studies were used to construct the Cases cohort; the Biobank's Controls cohort was used as the Control cohort. Odds ratios (OR) and False-discovery-rate (FDR) q values from multiple-hypotheses-testing corrections were used to assess the likelihood of DDD given occurrence of the listed DDD risk alleles.

RESULTS

Four-hundred-fourteen subjects (mean age = 64, range = 27 to 94) were Cases and 925 Controls (mean age = 46, range = 21-61). A systematic search has identified 25 SNPs in 18 genes in the SNP arrays. At univariate level, rs1544410 in VDR was significantly associated with DDD for male subjects (odds ratio [OR] = 0.594, P = 0.011). After adjustment for all significant variants and demographics, three predictor variables had a significant association with the outcome, age (OR = 1.130, q < 0.0001), rs143383 (OR = 1.951, q = 0.056), and rs3737821 (OR = 2.701, q = 0.069). A novel variant-to-variant correlation rs143383:rs763110 had a significant adjusted OR = 7.933, q = 0.070).

CONCLUSION

In this large-scale study of common variants' correlation with the presence of DDD in the Northeast United States, we have found a novel and significant variant-to-variant interaction to be associated with the risk of developing DDD, corroborating and necessitating the inclusion of gene-gene interactions in predictive risk model development for DDD.Level of Evidence: 4.

Matrilin3/TGFβ3 gelatin microparticles promote chondrogenesis, prevent hypertrophy, and induce paracrine release in MSC spheroid for disc regeneration

Degenerative disc disease (DDD) is the leading cause of excruciating lower back pain and disability in adults worldwide. Among the current treatments for DDD, cell-based therapies such as the injection of both disc- and non-disc-derived chondrocytes have shown significant improvements in the patients’ condition. However, further advancement of these therapies is required to not only ensure a supply of healthy chondrocytes but also to promote regeneration of the defective cells in the injury site. Here, we report that the incorporation of gelatin microparticles coloaded with transforming growth factor beta 3 and matrilin 3 promoted chondrogenic differentiation of adipose-derived mesenchymal stem cell spheroids while preventing hypertrophy and terminal differentiation of cells. Moreover, these composite spheroids induced the release of chondrogenic cytokines that, in turn, promoted regeneration of degenerative chondrocytes in vitro. Finally, injections of these composite spheroids in a rat model of intervertebral disc disease promoted restoration of the chondrogenic properties of the cells, thereby allowing regeneration of the chondrogenic tissue in vivo.

Prediction of a Potential Mechanism of Intervertebral Disc Degeneration Based on a Novel Competitive Endogenous RNA Network

Low back pain which resulted from intervertebral disc degeneration (IDD) is a common health problem that afflicts people all over the world. Due to the lack of an overall understanding of the molecular interactions involved in IDD, we hope to better understand the pathogenetic mechanisms that drive the degenerative process. The purpose of this study is to obtain mRNAs, miRNAs, lncRNAs, and circRNAs associated with IDD gained from public databases and to establish an interaction network. According to the results of microarray analysis and bioinformatics analysis from the contrast of IDD and normal nucleus pulposus tissues, a total of 49 mRNAs, 10 miRNAs, 30 lncRNAs, and 4 circRNAs were obtained and a lncRNA/circRNA–miRNA–mRNA interaction network was constructed. NEAT1–miR-5100–COL10A1 and miR663AHG/HEIH/hsa-circ-0003600–miR-4741–HAS2/HYAL1/LYVE1 might be potential interaction axes of the molecular mechanism in IDD. The increased expression of NEAT1 might inhibit miR-5100 and subsequently upregulate the expression of COL10A1, which leads to IDD, while the increased expression of miR663AHG/HEIH/hsa-circ-0003600 might inhibit miR-4741 and indirectly upregulate HAS2/HYAL1/LYVE1, and leads to the protection from IDD. More interaction axes are to be exploited to provide theoretical bases for further study on IDD.

Stem Cells and Intervertebral Disc Regeneration Overview-What They Can and Can't Do

BACKGROUND

Low back pain (LPB) is the main cause of disability worldwide with enormous socioeconomic burdens. A major cause of LBP is intervertebral disc degeneration (IDD): a chronic, progressive process associated with exhaustion of the resident cell population, tissue inflammation, degradation of the extracellular matrix and dehydration of the nucleus pulposus. Eventually, IDD may lead to serious sequelae including chronic LBP, disc herniation, segmental instability, and spinal stenosis, which may require invasive surgical interventions. However, no treatment is actually able to directly tackle IDD and hamper the degenerative process. In the last decade, the intradiscal injection of stem cells is raising as a promising approach to regenerate the intervertebral disc. This review aims to describe the rationale behind a regenerative stem cell therapy for IDD as well as the effect of stem cells following their implantation in the disc environment according to preclinical studies. Furthermore, actual clinical evidence and ongoing trials will be discussed, taking into account the future perspective and current limitations of this cutting-edge therapy.

METHODS

A literature analysis was performed for this narrative review. A database search of PubMed, Scopus and ClinicalTrials.gov was conducted using "stem cells" combined with "intervertebral disc", "degeneration" and "regeneration" without exclusion based on publication date. Articles were firstly screened on a title-abstract basis and, subsequently, full-text were reviewed. Both preclinical and clinical studies have been included.

RESULTS

The database search yielded recent publications from which the narrative review was completed.

CONCLUSIONS

Based on available evidence, intradiscal stem cell therapy has provided encouraging results in terms of regenerative effects and reduction of LBP. However, multicenter, prospective randomized trials are needed in order confirm the safety, efficacy and applicability of such a promising treatment.

MicroRNA‑25‑3p regulates human nucleus pulposus cell proliferation and apoptosis in intervertebral disc degeneration by targeting Bim

Intervertebral disc degeneration (IDD) is a degenerative disease of the spine originating from the intervertebral disc. MicroRNAs (miRNAs or miRs) are a group of endogenous small non‑coding RNAs that act on target genes and play a critical role in numerous biological processes. However, the underlying mechanism of miR‑25‑3p in IDD remains unclear. Therefore, the present study aimed to explore the role of miR‑25‑3p in the pathogenesis of IDD. The results demonstrated that miR‑25‑3p was downregulated in rat degenerative nucleus pulposus (NP) cells and that Bcl‑2 interacting mediator of cell death (Bim) was a direct target of miR‑25‑3p. Next, to investigate the effect of miR‑25‑3p on normal NP cell proliferation and apoptosis, NP cells were transfected with an miR‑25‑3p inhibitor, a negative control of miR‑25‑3p inhibitor, miR‑25‑3p inhibitor + control‑small interference RNA (siRNA) or miR‑25‑3p inhibitor + Bim‑siRNA for 48 h and cell proliferation and apoptosis were then analyzed. The results demonstrated that the miR‑25‑3p inhibitor could decrease NP cell proliferation and induce cell apoptosis, and these effects were reversed by Bim‑siRNA. In addition, an in vitro cell model of IDD was established by subjecting NP cells to 10 ng/ml interleukin (IL)‑1β for 24 h. Further experiments suggested that IL‑1β treatment induced a reduction in NP cell proliferation and an increase in cell apoptosis, which were prevented by the miR‑25‑3p mimic. All the effects of miR‑25‑3p mimic on IL‑1β‑treated NP cells were significantly reversed by Bim upregulation. These findings suggested that miR‑25‑3p may be a novel therapeutic target for IDD prevention.

Analysis of key genes and pathways associated with the pathogenesis of intervertebral disc degeneration

BACKGROUND

Intervertebral disc degeneration (IDD) is widely known as the main contributor to low back pain which has a negative socioeconomic impact worldwide. However, the underlying mechanism remains unclear. This study aims to analyze the dataset GSE23130 using bioinformatics methods to identify the pivotal genes and pathways associated with IDD.

MATERIAL/METHODS

The gene expression data of GSE23130 was downloaded, and differentially expressed genes (DEGs) were extracted from 8 samples and 15 controls. GO and KEGG pathway enrichment analyses were performed. Also, protein-protein interaction (PPI) network was constructed and visualized, followed by identification of hub genes and key module.

RESULTS

A total of 30 downregulated and 79 upregulated genes were identified. The DEGs were mainly enriched in the regulation of protein catabolic process, extracellular matrix organization, collagen fibril organization, and extracellular structure organization. Meanwhile, we found that most DEGs were primarily enriched in the PI3K-Akt signaling pathway. The top 10 hub genes were FN1, COL1A2, SPARC, COL3A1, CTGF, LUM, TIMP1, THBS2, COL5A2, and TGFB1.

CONCLUSIONS

In summary, key candidate genes and pathways were identified by using integrated bioinformatics analysis, which may provide insights into the underlying mechanisms and offer potential target genes for the treatment of IDD.

No evidence of a correlation between lumbar spinal subtypes and intervertebral disc degeneration among asymptomatic middle-aged and aged patients

The aim of the present study was to identify whether lumbar spinal subtypes (LSS) were associated with lumbar disc degeneration (LDD) among asymptomatic middle-aged and aged subjects. A cohort of 158 asymptomatic Chinese adults aged >40 years was recruited and 97 volunteers that met the inclusion criteria with complete information available were selected for inclusion. According to spinal morphology, volunteers were divided into four subtypes based on the classification of Roussouly. After baseline information was collected and spinopelvic parameters were measured, the data were compared among the four groups. According to the Pfirrmann classification, the degree of LDD was evaluated at each level on the MRI. For grades I-V, LDD at each level was effectively compared. Each of the four LSS from I to IV according to Roussouly classification from types I to IV were comprised of 25 (25.8%), 19 (19.6%), 38 (39.2%) and 15 (15.5%) of volunteers, respectively. Lumbar lordosis, sacral slope and pelvic incidence were significantly different among the four sub-types (P<0.001 for each), but no difference in pelvic tilt was observed (P=0.21). From types I to IV LSS, the proportion of disc degeneration was found to be 44, 52, 50 and 48%, respectively, which exhibited no statistically significant difference among LSS. No correlation between LSS and intervertebral disc degeneration was obtained among the asymptomatic middle-aged and aged subjects. The present study provides a reference for spinal surgery and indicated that additional risk factors should be assessed in the asymptomatic population of this age group, particularly in terms of differentially expressed genes.

Genetic risk factors for lumbar disc disease

AIM AND BACKGROUND

Lumbar disc degeneration (LDD) is thought to be multifactorial in origin. Very recently the focus has shifted to the involvement of a family of candidate genes in the pathogenesis of LDD. There is particular emphasis on the vitamin D receptor gene (VDR gene). The VDR polymorphisms FOK1, TAQ1, and APO1 have been variably associated with LDD.

OBJECTIVE

To evaluate the association between the FOK1/Taq1 genes and LDD.

MATERIALS AND METHODS

One hundred unrelated healthy (asymptomatic) individuals who presented for routine health checkup and 93 consecutive patients (43 males and 50 females) with no history of low back pain were enrolled in the study after informed consent was obtained. The MRI images of cases and controls were graded and peripheral blood samples were collected from all participants and sent for genetic analysis.

RESULTS

Individuals with the dominant genotype for Taq1 had a significantly higher association with LDD than those without it. There was no association between LDD and the Fok1 genotype.

CONCLUSION

Genetic predisposition is an important risk factor for LDD.

Association of the matrix metalloproteinase 3 (MMP3) single nucleotide polymorphisms with tendinopathies: case-control study in high-level athletes

BACKGROUND

Matrix metalloproteinases (MMPs) play an important role in matrix remodelling, as well as in tendon integrity. Due to overuse, athletes often develop chronic tendinopathies. If not treated, they lead to severe impairment, even complete tendon ruptures.

AIM

The main purpose of this study was to investigate whether three functional polymorphisms within the MMP3 gene are associated with increased risk of developing tendinopathies in high-level Croatian athletes.

METHODS

We have recruited one hundred fifty-five (63 high-level athletes with diagnosed tendinopathies and 92 asymptomatic controls) unrelated Caucasians for this case-control genetic study. All participants were genotyped for three single nucleotide polymorphisms (SNP) within the MMP3 gene: rs591058 C/T, rs650108 A/G and rs679620 G/A using the pyrosequencing method.

RESULTS

The MMP3 rs650108 GG (P = 0.0074) and rs679620 AA (P = 0.0119) genotypes were significantly over-represented in cases compared with controls, while rs591058 TT (P = 0.0759), as well as haplotype variant T - G - A (P = 0.06), implicated that there is an indication of predisposition for tendinopathies.

CONCLUSION

These results support association between functional variants within the MMP3 gene and the risk of tendinopathies in high-level athletes. Further research is needed to replicate these results in a larger population.

Lack of association between COL1A1 and COL9A2 single nucleotide polymorphisms and intervertebral disc degeneration

BACKGROUND

Collagens are the main components of the extracellular matrix of intervertebral discs. The genetic mutations in collagen genes could potentially play a causal role in pathophysiology of intervertebral disc degeneration (IVDD). In this study, we investigate the association of COL1A1 and COL9A2 single nucleotide polymorphisms (SNPs) with IVDD.

MATERIAL AND METHODS

ninety-six Iranian IVDD patients and 94 controls matched for age and sex were included. 5 cc of peripheral blood samples were obtained for DNA extraction using the Phenol-Chloroform method. The primers for SNPs COL1A1 rs909102 and COL9A2 were designed based on the TaqMan protocol and genotyped by real-time PCR with TaqMan.

RESULTS

The 'T' allele, 'CC' and 'TT' genotypes of COL1A1 rs909102 were more common among patients, however not significantly. Despite the similar allele distribution of COL9A2 rs137853213 in patients and controls, the homozygote genotypes were more frequent among patients, though this was not significant either.

CONCLUSION

The allele and genotype distributions of COL1A1 rs909102 and COL9A2 rs137853213 SNPs were not significantly associated with IVDD in an Iranian population.

Gene polymorphisms and expression levels of interleukin-6 and interleukin-10 in lumbar disc disease: a meta-analysis and immunohistochemical study

Background

To investigate the association between interleukin-6 (IL-6) (rs1800795, rs1800796, rs1800797, rs13306435, rs2069849) and interleukin-10 (IL-10) (rs1800871, rs1800896) gene polymorphisms, expression levels, and lumbar disc disease (LDD).

Methods

We conducted a literature research on PubMed, Embase, Web of Science, Cochrane Library, and China National Knowledge Infrastructure (CNKI) until February 28, 2019. We included all case-control studies about the association between IL-6 and IL-10 gene polymorphisms and LDD. The odds ratio (OR) and 95% confidence interval (CI) were calculated to estimate the strength of association. Statistical analysis was conducted by Review Manager (RevMan) 5.3 software. Furthermore, immunohistochemistry (IHC) and RT-PCR were performed to evaluate IL-6 and IL-10 expressions in the normal and degenerated disc.

Results

A total of 6 studies, involving 1456 cases and 1611 controls, were included in this meta-analysis. G alleles of rs1800795 and rs1800797 in the IL-6 gene were significantly associated with LDD (rs1800795: G vs. C, OR = 1.38, 95% CI = 1.16–1.64, P = 0.0002; rs1800797: G vs. A, OR = 1.35, 95% CI = 1.14–1.61, P = 0.0006). Begg’s funnel plot and Egger’s tests did not show any evidence of publication bias. IL-6 expression and IL-6 mRNA levels were significantly increased in the degenerated disc compared with those in the normal disc (IL-6 immunopositive cells, 73.68 ± 10.99% vs. 37.23 ± 6.42%, P < 0.001).

Conclusions

IL-6 gene polymorphisms (rs1800795 and rs1800797) were significantly associated with susceptibility to LDD. A high expression level of IL-6 may be an important risk factor for LDD.

Lessons learned from intervertebral disc pathophysiology to guide rational design of sequential delivery systems for therapeutic biological factors

Intervertebral disc (IVD) degeneration has been associated with low back pain, which is a major musculoskeletal disorder and socio-economic problem that affects as many as 600 million patients worldwide. Here, we first review the current knowledge of IVD physiology and physiopathological processes in terms of homeostasis regulation and consecutive events that lead to tissue degeneration. Recent progress with IVD restoration by anti-catabolic or pro-anabolic approaches are then analyzed, as are the design of macro-, micro-, and nano-platforms to control the delivery of such therapeutic agents. Finally, we hypothesize that a sequential delivery strategy that i) firstly targets the inflammatory, pro-catabolic microenvironment with release of anti-inflammatory or anti-catabolic cytokines; ii) secondly increases cell density in the less hostile microenvironment by endogenous cell recruitment or exogenous cell injection, and finally iii) enhances cellular synthesis of extracellular matrix with release of pro-anabolic factors, would constitute an innovative yet challenging approach to IVD regeneration.

Genetic Influence in Disc Degeneration - Systematic Review of Literature

Disc degeneration is a condition that compromises the intervertebral disc functions, which can lead to several important pathological processes, such as disc herniation and canal stenosis. Although its etiology is still unknown, more and more studies have demonstrated the preponderant role of genetic factors to the detriment of environmental factors. Aiming to review the current knowledge about the genes associated with intervertebral disc degeneration, we have performed a narrative review based on the medical literature in the English language from the last 10 years regarding this subject. We have concluded that several genes have been associated with disc degeneration in humans, including the genes for collagen I α-1 ( COL1A1 ), collagen IX ( COL9A2 and COL9A3 ), collagen XI ( COL11A2 ), interleukin 6 ( IL-6 ), aggrecan ( AGC1 ), vitamin D receptor ( VDR ), and matrix metalloproteinase 3 ( MMP-3) , in addition to microRNAs. Therefore, the present review emphasizes the latest advancements in the association of genes with specific phenotypes of degenerated discs, single-nucleotide polymorphisms, heritage and genetic-environmental interactions in relation to disc degeneration to help future reviews regarding the genetic mechanisms underlying these processes.

Downregulation of microRNA-129-5p increases the risk of intervertebral disc degeneration by promoting the apoptosis of nucleus pulposus cells via targeting BMP2

miR-129-5p is implicated in many diseases, such as laryngeal cancer and breast cancer. In this study, we studied the mechanism underlying the role of BMP2 in intervertebral disc degeneration (IDD). We used a luciferase assay system to determine the relationship between BMP2 and miR-129-5 expression. In addition, Western blot and real-time PCR were used to confirm the regulatory relationship between miR-129-5p and its targets, while flow cytometry was used to evaluate the effect of miR-129-5p on the apoptosis of neural progenitor cells (NPCs). BMP2 was confirmed as a direct target of miR-129-5p. Furthermore, the expression of miR-129 was downregulated along with upregulated BMP2 expression in IDD patients. Meanwhile, BMP2 was validated as the target of miR-129-5p in cells transfected with miR-129-5p and BMP2 siRNA. Also, compared with NPCs transfected with blank/scramble controls or miR-129-5p inhibitors, the NPCs treated with miR-129-5p mimics or BMP2 siRNA exhibited evidently elevated viability and inhibited apoptosis. The data demonstrated that miR-129-5p was poorly expressed in IDD patients, and the dysregulation of miR-129-5p might contribute to the development of IDD by targeting BMP2 expression.

Vitamin D Receptor gene polymorphisms and plasma levels are associated with lumbar disc degeneration

The purpose of this study was to investigate the association of Vitamin D Receptor (VDR) gene polymorphisms and VDR levels with lumbar disc degeneration (LDD). TaqMan SNP Genotyping Assay was utilized to probe VDR gene polymorphisms including the FokI (rs2228570), ApaI (rs7975232) and TaqI (rs731236) in 454 patients with LDD and 485 controls. Enzyme-Linked Immunosorbent Assay (ELISA) was used to detect plasma VDR levels. The patients with LDD were divided into three subgroups (subgroup 1: lumbar disc herniation; subgroup 2: lumbar spinal stenosis; subgroup 3: lumbar spondylolisthesis) to further probe the association of plasma VDR levels and VDR gene polymorphisms and LDD. Moreover, immunohistochemistry (IHC) was implemented to evaluate VDR expression in lumbar degenerated disc and normal disc. Allele and genotype frequency of TaqI (rs731236) were significantly different in patients with LDD and controls (all P < 0.05). For TaqI polymorphism, the frequencies of T allele were significantly higher in the LDD patients compared with controls (OR = 1.319; 95%CI 1.091 to 1.595; P = 0.004, adjusted (OR = 1.319; 95%CI 1.091 to 1.595; P = 0.004, adjusted OR = 1.383; 95%CI 1.135 to 1.684; P = 0.016). Furthermore, the allele distribution showed a higher frequency of the T allele in the patients with lumbar disc herniation in subgroup 1 (OR = 1.384; 95% CI 1.105 to 1.732; P = 0.004, adjusted OR = 1.319; 95%CI 1.091 to 1.595; P = 0.016). Plasma VDR levels and VDR expression were significantly lower in patients with LDD compared with controls (all P < 0.05). Moreover, the TT genotype of TaqI polymorphism was significantly associated with lower plasma VDR levels in patients with LDD (P = 0.002). TaqI (rs731236) polymorphism was associated with a predisposition to LDD. Plasma VDR and VDR expression levels may be the marker for the occurrence and development of LDD.

Effects of Oxygen Concentration and Culture Time on Porcine Nucleus Pulposus Cell Metabolism: An in vitro Study

Low back pain is a common ailment that affects millions of individuals each year and is linked to degeneration of the intervertebral discs in the spine. Intervertebral disc degeneration is known to result from an imbalance in anabolic and catabolic activity by disc cells. Due to the avascular nature of the intervertebral disc, oxygen deficiency may occur in the central nucleus pulposus (NP). The resulting hypoxia affects matrix regulation and energy metabolism of disc cells, although the mechanisms are not fully understood. This study investigates in vitro glucose consumption and gene expression by NP cells over time under varying oxygen tensions. Notochordal porcine NP cells were cultured in agarose discs at 21, 5, or 1% oxygen tension for 1, 5, or 10 days. The expression of 10 key matrix genes, as well as Brachyury (T), by NP cells was analyzed using RT-PCR. Glucose consumption was measured using a two-point method. Results show that culture time and oxygen tension significantly affect glucose consumption rates by porcine NP cells. There were also significant changes in T expression based on oxygen level and culture time. The 1% oxygen tension had a significantly higher T expression on day 10 than the other two groups, which may indicate a better maintenance of the notochordal phenotype. MMP 1 and 13 expression increased over time for all groups, while only the 5% group showed an increase over time for MMP 3. TIMP expression followed the direction of MMPs but to a lesser magnitude. Five percent and twenty-one percent oxygen tensions led to decreases in anabolic gene expression while 1% led to increases. Oxygen concentration and culture time significantly impacted glucose consumption rate and the gene expression of matrix regulatory genes with hypoxic conditions most accurately maintaining the proper NP phenotype. This information is valuable not only for understanding disc pathophysiology, but also for harnessing the potential of notochordal NP cells in therapeutic applications.

A Novel Non-invasive Effective Method for Potential Treatment of Degenerative Disc Disease: A Hypothesis

The pathophysiology of the intervertebral discs plays a significant role in the people's life quality. There is not adequate research done in the pathogenesis and treatment of intervertebral disc degeneration. Alternately, self-educated physiology offers a novel and noninvasive method to reverse the degenerated discs. In this single case study, report attempts have been made to highlight the effect of the self-educative physiology, on magnetic resonance imaging investigations, of progressive healing, on the degenerated intervertebral discs. Based on this novel method, an effort has been made to review literature on the degeneration of intervertebral discs and available mode of treatments and then to propose a hypothesis for the biochemical mechanisms of healing. The idea is that transforming growth factor-β1 from seminal plasma secretions may contribute to releasing the osteogenic protein- 1 which induces nucleus pulposus and annulus fibrosus cells in intervertebral discs for repairs. In addition, the patient's medical history is presented with background information.

Frequency-dependent shear properties of annulus fibrosus and nucleus pulposus by magnetic resonance elastography

Aging and degeneration are associated with changes in mechanical properties in the intervertebral disc, generating interest in the establishment of mechanical properties as early biomarkers for the degenerative cascade. Magnetic resonance elastography (MRE) of the intervertebral disc is usually limited to the nucleus pulposus, as the annulus fibrosus is stiffer and less hydrated. The objective of this work was to adapt high-frequency needle MRE to the characterization of the shear modulus of both the nucleus pulposus and annulus fibrosus. Bovine intervertebral discs were removed from fresh oxtails and characterized by needle MRE. The needle was inserted in the center of the disc and vibrations were generated by an amplified piezoelectric actuator. MRE acquisitions were performed on a 4.7-T small-animal MR scanner using a spin echo sequence with sinusoidal motion encoding gradients. Acquisitions were repeated over a frequency range of 1000-1800 Hz. The local frequency estimation inversion algorithm was used to compute the shear modulus. Stiffness maps allowed the visualization of the soft nucleus pulposus surrounded by the stiffer annulus fibrosus surrounded by the homogeneous gel. A significant difference in shear modulus between the nucleus pulposus and annulus fibrosus, and an increase in the shear modulus with excitation frequency, were observed, in agreement with the literature. This study demonstrates that global characterization of both the nucleus pulposus and annulus fibrosus of the intervertebral disc is possible with needle MRE using a preclinical magnetic resonance imaging (MRI) scanner. MRE can be a powerful method for the mapping of the complex properties of the intervertebral disc. The developed method could be adapted for in situ use by preserving adjacent vertebrae and puncturing the side of the intervertebral disc, thereby allowing an assessment of the contribution of osmotic pressure to the mechanical behavior of the intervertebral disc.

Effect of disc degeneration on the mechanical behavior of the human lumbar spine: a probabilistic finite element study

BACKGROUND CONTEXT

Intervertebral disc degeneration has been subject to numerous in vivo and in vitro investigations and numerical studies during recent decades, reporting partially contradictory findings. However, most of the previous studies were limited in the number of specimens investigated and, therefore, could not consider the vast variety of the specimen geometries, which are likely to strongly influence the mechanical behavior of the spine.

PURPOSE

To complement the understanding of the mechanical consequences of disc degeneration, whereas considering natural variations in the major spinal geometrical parameters.

DESIGN/SETTING

A probabilistic finite element study.

METHODS

A parametric finite element model of a human L4-L5 motion segment considering 40 geometrical parameters was developed. One thousand individual geometries comprising four degeneration grades were generated in a probabilistic manner, and the influence of the severity of disc degeneration on the mechanical response of the motion segment to different loading conditions was statistically evaluated.

RESULTS

Variations in the individual structural parameters resulted in marked variations in all evaluated parameters within each degeneration grade. Nevertheless, the effect of degeneration in almost all evaluated response values was statistically significant. With degeneration, the intradiscal pressure progressively decreased. At the same time, the facet loads increased and the ligament tension was reduced. The initially nonlinear load-deformation relationships became linear whereas the segment stiffness increased.

CONCLUSIONS

Results indicate significant stiffening of the motion segment with progressing degeneration and gradually increasing loading of the facets from nondegenerated to moderately degenerated conditions along with a significant reduction of the ligament tension in flexion.

Genetic background of degenerative disc disease in the lumbar spine

This is a review paper on the topic of genetic background of degenerative disc diseases in the lumbar spine. Lumbar disc diseases (LDDs), such as lumbar disc degeneration and lumbar disc herniation, are the main cause of low back pain. There are a lot of studies that tried to identify the causes of LDDs. The causes have been categorized into environmental factors and genetic factors. Recent studies revealed that LDDs are mainly caused by genetic factors. Numerous studies have been carried out using the genetic approach for LDDs. The history of these studies is divided into three periods: (1) era of epidemiological research using familial background and twins, (2) era of genomic research using DNA polymorphisms to identify susceptible genes for LDDs, and (3) era of functional research to determine how the genes cause LDDs. This review article was undertaken to present the history of genetic approach to LDDs and to discuss the current issues and future perspectives.

Cartilage intermediate layer protein 1 (CILP1): A novel mediator of cardiac extracellular matrix remodelling

Heart failure is accompanied by extracellular matrix (ECM) remodelling, often leading to cardiac fibrosis. In the present study we explored the significance of cartilage intermediate layer protein 1 (CILP1) as a novel mediator of cardiac ECM remodelling. Whole genome transcriptional analysis of human cardiac tissue samples revealed a strong association of CILP1 with many structural (e.g. COL1A2 r² = 0.83) and non-structural (e.g. TGFB3 r² = 0.75) ECM proteins. Gene enrichment analysis further underscored the involvement of CILP1 in human cardiac ECM remodelling and TGFβ signalling. Myocardial CILP1 protein levels were significantly elevated in human infarct tissue and in aortic valve stenosis patients. CILP1 mRNA levels markedly increased in mouse heart after myocardial infarction, transverse aortic constriction, and angiotensin II treatment. Cardiac fibroblasts were found to be the primary source of cardiac CILP1 expression. Recombinant CILP1 inhibited TGFβ-induced αSMA gene and protein expression in cardiac fibroblasts. In addition, CILP1 overexpression in HEK293 cells strongly (5-fold p < 0.05) inhibited TGFβ signalling activity. In conclusion, our study identifies CILP1 as a new cardiac matricellular protein interfering with pro-fibrotic TGFβ signalling, and as a novel sensitive marker for cardiac fibrosis.

The Interface of Mechanics and Nociception in Joint Pathophysiology: Insights From the Facet and Temporomandibular Joints

Chronic joint pain is a widespread problem that frequently occurs with aging and trauma. Pain occurs most often in synovial joints, the body's load bearing joints. The mechanical and molecular mechanisms contributing to synovial joint pain are reviewed using two examples, the cervical spinal facet joints and the temporomandibular joint (TMJ). Although much work has focused on the macroscale mechanics of joints in health and disease, the combined influence of tissue mechanics, molecular processes, and nociception in joint pain has only recently become a focus. Trauma and repeated loading can induce structural and biochemical changes in joints, altering their microenvironment and modifying the biomechanics of their constitutive tissues, which themselves are innervated. Peripheral pain sensors can become activated in response to changes in the joint microenvironment and relay pain signals to the spinal cord and brain where pain is processed and perceived. In some cases, pain circuitry is permanently changed, which may be a potential mechanism for sustained joint pain. However, it is most likely that alterations in both the joint microenvironment and the central nervous system (CNS) contribute to chronic pain. As such, the challenge of treating joint pain and degeneration is temporally and spatially complicated. This review summarizes anatomy, physiology, and pathophysiology of these joints and the sensory pain relays. Pain pathways are postulated to be sensitized by many factors, including degeneration and biochemical priming, with effects on thresholds for mechanical injury and/or dysfunction. Initiators of joint pain are discussed in the context of clinical challenges including the diagnosis and treatment of pain.

Does sedentary behavior increase the risk of low back pain? A population-based co-twin study of Spanish twins

BACKGROUND

The relationship between sedentary lifestyle and low back pain (LBP) remains unclear and previous research has not accounted for genetic and early environmental factors.

PURPOSE

Our aim was to investigate if sedentary behavior is associated with the lifetime prevalence of persistent LBP and the risk of developing persistent LBP, care-seeking due to LBP, and activity limiting LBP when genetics and early environmental factors are accounted for.

STUDY DESIGN

Both cross-sectional and longitudinal designs with a within-pair twin case-control were implemented.

PATIENT SAMPLE

There were 2,148 twins included in the cross-sectional analysis whereas 1,098 twins free of persistent LBP at baseline were included in the longitudinal analysis.

OUTCOME MEASURES

Sedentary behavior was the explanatory variable. Lifetime prevalence of LBP was the outcome variable in the cross-sectional analysis. The incidence of persistent LBP, care-seeking due to LBP, and activity limiting LBP were the outcome variables for the longitudinal analysis.

METHODS

This observational study was supported by a grant in 2012. No competing interests were declared.

RESULTS

In the cross-sectional analysis, sedentary behavior was slightly associated with an increased prevalence of persistent LBP in females but not in males. This association was not apparent when genetics and early environmental factors were accounted for. We acknowledge that the small sample included in the co-twin analyses have yielded wide confidence intervals, and that caution should be exercised when interpreting and an association may not be ruled out. In the longitudinal analysis, sedentary behavior did not significantly increase the risk of persistent LBP, care-seeking due to LBP, or activity limiting LBP.

CONCLUSIONS

Sedentary behavior is associated with concurrent LBP. However, this association is weak; it only appears in females and decreases when accounting for genetics. Future studies using a twin design with larger samples should be conducted to further test these findings.

Single Nucleotide Variants of Candidate Genes in Aggrecan Metabolic Pathway Are Associated with Lumbar Disc Degeneration and Modic Changes

Introduction

Lumbar disc degeneration (LDD) is genetically determined and severity of LDD is associated with Modic changes. Aggrecan is a major proteoglycan in the intervertebral disc and end plate. Progressive reduction of aggrecan is a main feature of LDD and Modic changes.

Objectives

The study investigated the associations of single nucleotide variants (SNVs) of candidate genes in the aggrecan metabolic pathway with the severity of LDD and Modic changes. In-silico functional analysis of significant SNVs was also assessed.

Methods

A descriptive cross sectional study was carried out on 106 patients with chronic mechanical low back pain. T1, T2 sagittal lumbar MRI scans were used to assess the severity of LDD and Modic changes. 62 SNVs in ten candidate genes (ACAN, IL1A, IL1B, IL6, MMP3, ADAMTS4, ADAMTS5, TIMP1, TIMP2 and TIMP3) were genotyped on Sequenom MassARRAY iPLEX platform. Multiple linear regression analysis was carried out using PLINK 1.9 in accordance with additive genetic model. In-silico functional analysis was carried out using Provean, SIFT, PolyPhen and Mutation Taster.

Results

Mean age was 52.42±9.42 years. 74 (69.8%) were females. The rs2856836, rs1304037, rs17561 and rs1800587 variants of the IL1A gene were associated with the severity of LDD and Modic changes. The rs41270041 variant of the ADAMTS4 gene and the rs226794 variant of the ADAMTS5 gene were associated with severity of LDD while the rs34884997 variant of the ADAMTS4 gene, the rs55933916 variant of the ADAMTS5 gene and the rs9862 variant of the TIMP3 gene were associated with severity of Modic changes. The rs17561 variant of the IL1A gene was predicted as pathogenic by the PolyPhen prediction tool.

Conclusions

SNVs of candidate genes in ACAN metabolic pathway are associated with severity of LDD and Modic changes in patients with chronic mechanical low back pain. Predictions of in-silico functional analysis of significant SNVs are inconsistent.

MRI Phenotyping of COL9A2/Trp2 and COL9A3/Trp3 Alleles in Lumbar Disc Disease: A Case-control Study in South-Western Iranian Population Reveals a Significant Trp3-Disease Association in Males

STUDY DESIGN

A case-control study of the Trp2/3 alleles of COL9A2/3 genes and their correlation with occurrence of Lumbar disc disease (DDD) as phenotyped by magnetic resonance imaging.

OBJECTIVE

To establish a better understanding of relationship between presence of said alleles and occurrence of DDD in South-Western Iranian population.

SUMMARY OF BACKGROUND DATA

A number of genetic predisposing factors have been identified in elevating the risk of developing DDD. Specifically, the Trp2 and Trp3 alleles of COL9A2 and COL9A3 genes have been suggested as DDD risk variants.

METHODS

A total of 108 patients (mean age = 41±11.8 yrs, range = 20-66 yrs) with 57 controls (mean age = 35±10.0 yrs, range = 20-58 yrs) participated in the study. The frequency of G/A polymorphism in COL9A2 gene on location 326 on chromosome 1 and G/A/C/ or T polymorphism in 103 location of COL9A3 gene on chromosome 20 was assessed using a PCR short-primer technique. Outcome measure was defined as presence of DDD on MRI. Odds ratios (OR) and 95% confidence intervals (CI) were used to assess the likelihood of DDD given occurrence of Trp2(3).

RESULTS

Each allele was present in both patients and controls. The Trp2 allele was positive in 28.5% of individuals (31.5% of patients; 22.8% of controls), OR 1.55 (0.71-3.56). The Trp3 allele, the frequency was 23.6% in all patients (26.9% patients; 17.5% controls), OR 1.72 (0.73-4.33). We observed a 5.8-fold increase in the odds of DDD in males when the Trp3 allele was present, OR 5.83 (1.09-9.98), P = 0.0273.

CONCLUSION

Both Trp2 and Trp3 alleles occurred more frequently compared with other studied ethnicities. The sampled Iranian population exhibited a similar Trp2 frequency to a Southern Chinese population, and Trp3 occurrence to Finnish and Greek population. We found that male patient were much more likely to develop DDD when Trp 3 was present.

LEVEL OF EVIDENCE

N/A.

Genetic aspects of intervertebral disc degeneration

Intervertebral disc degeneration (IVDD) is one of the common causes of low back pain. Similar to many other multifactorial diseases, it is affected by environmental and genetic factors. Although not completely understood, genetic factors include a wide spectrum of variations, such as single nucleotide polymorphisms, which could play a significant role in the etiology of this disease. Besides, the interactions with environmental factors could make the role of genetic factors more complicated. Genetic variations in disc components could participate in developing degenerative disc disease through altering the normal homeostasis of discs. Gene polymorphisms in disc proteins (collagens I, II, III, IX, and XI), proteoglycans (aggrecan), cytokines (interleukins I, VI, and X), enzymes (matrix metalloproteinases II, III, and IX), and vitamin D receptor seem to play considerable roles in the pathology of this disease. There are also many other investigated genes that could somehow take part in the process. However, it seems that more studies are needed to clarify the exact role of genetics in IVDD.

The Association Between Low Back Pain and Composition of IgG Glycome

Low back pain (LBP) is a common debilitating condition which aetiology and pathogenesis are poorly understood. We carried out a first so far analysis of associations between LBP and plasma IgG N-glycome in a sample of 4511 twins from TwinsUK database assessed for LBP, lumbar disc degeneration (LDD) as its possible cause, and IgG-glycan levels. Using weighted correlation network analysis, we established a correlation between LBP and glycan modules featured by glycans that either promote or block antibody-dependent cell-mediated cytotoxicity (ADCC). The levels of four glycan traits representing two of those modules were statistically significantly different in monozygotic twins discordant for LBP. Also, the trend to higher prevalence of systemic inflammatory disorders was shown for twins with low level of fucosylated glycans and high level of non-fucosylated glycans. Core fucosylation of IgG is a “safety switch” reducing ADCC, thus our results suggest the involvement of ADCC and associated inflammation in pathogenesis of LBP. No correlation between LDD scores and glycans was found assuming that the inflammation may not be a part of LDD. These data provide a new insight into understanding the complex pathophysiology of LBP and suggest glycan levels as a possible biomarker for inflammation-related subtypes of LBP.

Genetic Factors in Intervertebral Disc Degeneration

Low back pain (LBP) is a major cause of disability and imposes huge economic burdens on human society worldwide. Among many factors responsible for LBP, intervertebral disc degeneration (IDD) is the most common disorder and is a target for intervention. The etiology of IDD is complex and its mechanism is still not completely understood. Many factors such as aging, spine deformities and diseases, spine injuries, and genetic factors are involved in the pathogenesis of IDD. In this review, we will focus on the recent advances in studies on the most promising and extensively examined genetic factors associated with IDD in humans. A number of genetic defects have been correlated with structural and functional changes within the intervertebral disc (IVD), which may compromise the disc's mechanical properties and metabolic activities. These genetic and proteomic studies have begun to shed light on the molecular basis of IDD, suggesting that genetic factors are important contributors to the onset and progression of IDD. By continuing to improve our understanding of the molecular mechanisms of IDD, specific early diagnosis and more effective treatments for this disabling disease will be possible in the future.

Elevated interleukin-6 expression levels are associated with intervertebral disc degeneration

The present study aimed to investigate whether serum interleukin-6 (IL-6) expression levels were associated with the onset and progression of intervertebral disc degeneration (IDD). A comprehensive meta-analysis of the scientific literature from numerous electronic databases was performed, in order to obtain published studies associated with the topic of interest. Relevant case-control studies that had previously assessed a correlation between IL-6 expression levels and IDD were identified using predetermined inclusion and exclusion criteria. The STATA version 12.0 software was used for statistical analysis of the extracted data. A total of 112 studies were initially retrieved, with eight studies meeting the inclusion criteria. These contained a total of 392 subjects, of which 263 were patients with IDD and 129 were healthy controls. A meta-analysis of the eight studies demonstrated that serum IL-6 protein expression levels may be associated with IDD, and this was irrespective of IDD subtype (bulging, protrusion, or sequestration). Notably, serum expression levels of the IL-6 protein were upregulated in intervertebral disc (IVD) protrusion tissue, as compared with normal IVD tissue; thus suggesting that IL-6 may have an important role in the pathophysiological process of IDD.

Aging and degeneration of the intervertebral disc: review of basic science

<p>Currently there is a growing interest in the study of intervertebral discs due to loss of manpower brought to society by low back and neck pains. These papers seek to delineate the difference between normal aging and disc degeneration, trying to understand what factor would be determining for the second condition. Thus, the morphology field was expanded and knowledge on the structure of intervertebral discs currently uses the research field of cell and molecular biology, and genetics. The results indicate that regardless of age or condition, the intervertebral disc undergoes long and extensive remodeling of its constituents, which are influenced by several factors: environmental, soluble, cell growth and extracellular matrix. In this literature review we describe the biological characteristics of the cervical and lumbar intervertebral disc with a focus on basic science of aging and degeneration, selecting the latest findings and discussions of the area, which influence future research and clinical thoughts.</p>

Fractalkine receptor chemokine (CX3CR1) influences on cervical and lumbar disc herniation

BACKGROUND

Herniation of nuclear or disc material along with, inflammatory chemokines such as prostaglandin E2, interleukin-6, matrix metalloproteinase and nitric oxide has definite correlation, possibly they are over produced. CX3CL1 and its receptor (CX3CR1) are part of chemokine system involved in leukocyte recruitment and adhesion in chronic inflammatory disease, but its role in spinal herniated nucleus pulposus (HNP) is unknown. We evaluated the expression of CX3CL1 and CX3CR1 in patients with disc herniation to clarify the role of CX3CL1 and CX3CR1 in the disc degeneration and to compare between cervical and lumbar HNP.

MATERIALS AND METHODS

The mRNA concentrations of CX3CL1/CX3CR1 chemokine were analyzed in the surgically obtained disc specimens from C-HNP (n = 13) and L-HNP (n = 13) by real-time polymerase chain reaction (PCR). The localization of CX3CL1/CX3CR1 chemokine in the disc of C-HNP and L-HNP patients was determined using immunohistochemical study. Blood samples from patients with C-HNP and L-HNP patients were stained for CX3CR1 with flow cytometric analysis.

RESULTS

The CX3CL1 positive cell ratio in the discs was observed in both groups by immunohistochemical study. CX3CR1 was strongly expressed on endothelial cells in C-spine disc, but sparely expressed in L-spine disc. There was greater CX3CR1 mRNA expression in C-HNP patients than in L-HNP patients as quantified by reversal transcription-PCR (P = 0.010). CX3CR1 positive cell frequencies and CX3CR1 expression levels were increased in CD4 (+) T-cells and natural killer (NK) cells from patients with C-HNP (P = 0.210 and P = 0.040).

CONCLUSIONS

This study identified that increases in CX3CL1 and CX3CR1-expressing cells are significantly related to pathomechanism of HNP for the first time. Especially, CD4 (+) T-cells and NK cells expressing CX3CR1 may play an important role in developing C-HNP.

Analysis of FokI polymorphism of vitamin D receptor gene in intervertebral disc degeneration

AIM

We have hypothesized a possible relationship between disc degeneration (DD) and VDR FokI/T2C polymorphism.

METHODS

A case-control study was performed comprising 121 Brazilian patients with confirmed DD by nuclear magnetic resonance and a control group consisting of 131 healthy patients without a history of disc cysts of the lumbar spine. Detection of VDR FokI/T2C polymorphism was performed using restriction fragment length polymorphism-polymerase chain reaction. The chi-square test was used to compare allele and genotype frequencies between groups, and a p-value of <0.05 was considered statistically significant.

RESULTS

The results disclosed statistical difference between allele distribution among cases and controls (p=0.025, odds ratio=1.58, confidence interval=1.07-2.32) considering VDR FokI/T2C polymorphism.

CONCLUSION

The results showed a positive association between VDR FokI/T2C polymorphism and DD in Brazilian patients tested.

Matrix metalloproteinase-3, vitamin D receptor gene polymorphisms, and occupational risk factors in lumbar disc degeneration

BACKGROUND

Lumbar disc degeneration (LDD) is a process that begins early in life, contributing to the development of low back pain. LDD is a consequence of a variety of factors, and its etiology remains poorly understood. Objectives to investigate occupational and genetic risk factors inducing lumbar disc degeneration, and to evaluate the possible association of genetic polymorphisms of matrix metalloproteinase 3 (MMP-3) and vitamin D receptor (VDR) with the severity of LDD in an Egyptian population.

SUBJECTS AND METHODS

A case control study involving 84 LDD and 60 controls was carried out. Five types of work related factors were investigated by questionnaire, complete neurological examination for all subjects and MRI for the cases. Polymerase chain reaction and restriction fragment length polymorphism methods were applied to detect polymorphisms in MMP-3 Promoter (-1,171 6A/5A) (rs 731236) and VDR-Apa (rs 35068180).

RESULTS

We found that family history, back injury, smoking, high level of sitting, bending/twisting, physical workload, lifting, whole body vibration, mutant allele 5A of MMP-3 and mutant allele T of VDR were significantly associated with LDD (OR = 2.9, 3.1, 2.1, 11.1, 15.9, 11.7, 8.2, 12.6, 2.5 and 3.1 respectively, p < 0.05). Cases that carry allele 5A and/or allele T were associated with LDD severity.

CONCLUSION

LDD is closely associated in occurrence and severity with occupational, environmental risk factors and susceptibility genes namely MMP-3, and VDR (ApaI). This study throws light on the importance of screening for early detection of susceptible individuals and disease prevention.

Is there any relation between cervical cord plaques and discopathy in patients with multiple sclerosis?

INTRODUCTION

Multiple sclerosis (MS) is the most common chronic autoimmune demyelinating disease of the central nervous system. The purpose of this study is to determine the relationship between the site of the cervical discopathy and cervical spinal cord plaque in MS patients.

METHODS

This retrospective study included all patients with a definite diagnosis of MS who were treated at an outpatient clinic between September 2004 and September 2011. All patients underwent cervical magnetic resonance imaging (MRI) for primary investigation of the disease. Cervical MRI scans were evaluated for detection of any evidence of cervical discopathy and cervical MS plaques. Any correlation between the site of the MS lesions and discopathy was recorded.

RESULTS

From 536 patients who were involved in the study, 214 patients had both cervical discopathy and cervical cord plaques. In this group 148 (69.1% of patients) had cervical plaque at the same site of cervical discopathy. The number of patients with cervical cord plaque and discopathy at same site was significantly higher than those with plaque and discopathy at different sites (P<0.05).

CONCLUSION

The study data suggests a possible correlation between cervical discopathy and cervical MS plaque.

Characterization of microRNA expression profiles in patients with intervertebral disc degeneration

Intervertebral disc degeneration (IDD) is associated with lower back pain and is a global burden with severe healthcare and socioeconomic consequences. However, the underlying mechanisms of IDD remain largely unelucidated. Accumulating evidence has indicasted that newly defined gene regulators, microRNAs (miRNAs), play a vital role in neurodegenerative, pathophysiological and certain reproductive disorders. To characterize the differential miRNA expression profiles between IDD and spinal cord injury, specimens from 3 patients with IDD and 3 with spinal cord injury were selected for microarray analysis. Total RNA from these 6 specimens was extracted and subjected to global miRNA expression analysis using the Exiqon miRCURY™ LNA Array (v.16.0). The microarray data were then validated by quantitative reverse transcription polymerase chain reaction (qRT-PCR). In addition, bioinformatics analysis was performed to investigate the dysregulated miRNA target genes and signaling pathways involved. Among the miRNAs analyzed, 25 miRNAs were found to be upregulated and 26 were found to be downregulated in the IDD group compared with the spinal cord injury group. The qRT-PCR results validated the microarray data. Bioinformatics analysis indicated that the signaling pathways most likely to be controlled by these miRNAs were the phosphoinositide 3-kinase (PI3K)-Akt, mitogen-activated protein kinase (MAPK), epidermal growth factor receptor (EGFR; ErbB) and Wnt pathways. Our results demonstrated that the miRNA expression in patients with IDD differed significantly from that in patients who sustained injury to the intervertebral disc. Our data indicate that the dysregulated miRNAs control the signaling pathways important for the maintenance of IDD. Further studies on miRNA target gene identification and biological functions may address the specific regulatory mechanisms of miRNAs in IDD, and may provide valuable insight into the diagnosis and treatment of IDD.

Assessment of the matrix degenerative effects of MMP-3, ADAMTS-4, and HTRA1, injected into a bovine intervertebral disc organ culture model

STUDY DESIGN

In vitro study to develop an intervertebral disc degeneration organ culture model, using coccygeal bovine intervertebral discs (IVDs) and injection of proteolytic enzymes MMP-3, ADAMTS-4, and HTRA1.

OBJECTIVE

This study aimed to develop an in vitro model of enzyme-mediated intervertebral disc degeneration to mimic the clinical outcome in humans for investigation of therapeutic treatment options.

SUMMARY OF BACKGROUND DATA

Bovine IVDs are comparable with human IVDs in terms of cell composition and biomechanical behavior. Researchers injected papain and trypsin into them to create an intervertebral disc degeneration model with a degenerated nucleus pulposus (NP) area. They achieved macroscopic cavities as well as a loss of glycosaminoglycans (GAGs). However, none of these enzymes are clinically relevant.

METHODS

Bovine IVDs were harvested maintaining the endplates. Active forms of MMP-3, ADAMTS-4, and HTRA1 were injected at a dose of 10 μg/mL each. Phosphate-buffered saline was injected as a control. Discs were cultured for 8 days and loaded diurnally (days 1-4 with ≈0.4 MPa for 16 hr) and left under free swelling condition from days 4 to 8 to avoid expected artifacts because of dehydration of the NP. Outcome parameters included disc height, metabolic cell activity, DNA content, GAG content, total collagen content, relative gene expression, and histological investigation.

RESULTS

The mean metabolic cell activity was significantly lower in the NP area of discs injected with ADAMTS-4 than the day 0 control discs. Disc height was decreased after injection with HTRA1 and was significantly correlated with changes in GAG/DNA of the NP tissue. Total collagen content tended to be lower in groups injected with ADAMTS4 and MMP-3.

CONCLUSION

MMP-3, ADAMTS-4, and HTRA1 provoked neither visible matrix degradation nor major shifts in gene expression. However, cell activity was significantly reduced and HTRA1 induced loss of disc height that positively correlated with changes in GAG/DNA content. The use of higher doses of these enzymes or a combination thereof may, therefore, be necessary to induce disc degeneration.

At the borders of medical reasoning: aetiological and ontological challenges of medically unexplained symptoms

Medically unexplained symptoms (MUS) remain recalcitrant to the medical profession, proving less suitable for homogenic treatment with respect to their aetiology, taxonomy and diagnosis. While the majority of existing medical research methods are designed for large scale population data and sufficiently homogenous groups, MUS are characterised by their heterogenic and complex nature. As a result, MUS seem to resist medical scrutiny in a way that other conditions do not. This paper approaches the problem of MUS from a philosophical point of view. The aim is to first consider the epistemological problem of MUS in a wider ontological and phenomenological context, particularly in relation to causation. Second, the paper links current medical practice to certain ontological assumptions. Finally, the outlines of an alternative ontology of causation are offered which place characteristic features of MUS, such as genuine complexity, context-sensitivity, holism and medical uniqueness at the centre of any causal set-up, and not only for MUS. This alternative ontology provides a framework in which to better understand complex medical conditions in relation to both their nature and their associated research activity.