Vascular endothelial growth factor gene variations as a risk predictor in disc degeneration / Variação do gene fator de crescimento endotelial vascular como preditor de risco para a degeneração discal

ABSTRACT Objective: To evaluate the frequency of polymorphisms in the vascular endothelial growth factor (VEGF) gene, as well as to identify a potential risk haplotype among the polymorphic regions in this gene in patients with disc degeneration and in the Control Group. Methods: This study analyzed a total of 217 individuals distributed into the Disc Degeneration and Control Groups. Peripheral blood was collected from all patients to detect VEGF gene polymorphisms identified by qPCR (rs699947, rs1570360, rs2010963, rs833061 and rs3025039). All patients presenting disc degeneration had the confirmation by nuclear magnetic resonance test and were rated according to disc degeneration level. Results: All polymorphisms were in Hardy- Weinberg equilibrium (p>0.05) in the studied population. The genotypic frequency for Disc Degeneration and Control Group were rs699947 p = 0.475, rs1570360 p = 0.862, rs2010963 p = 0.823, rs833061 p=0.596 and rs3025039 p=0.230. In haplotype analysis, the compositions CAGGC (p=0.094) and CCGGC (p=0.054) stood out. Conclusion: The correlation between VEGF gene polymorphism as a risk predictor for disc degeneration was negative in the studied population. However, the VEGF gene has a large polymorphic region, and it is activated by various catabolic and metabolic factors in the disc degeneration process, which has not been fully elucidated.

RESUMO Objetivo: Avaliar a frequência dos polimorfismos no gene fator de crescimento endotelial vascular (VEGF), bem como identificar potencial haplótipo de risco entre as regiões polimórficas deste gene em pacientes com degeneração discal e em Grupo Controle. Métodos: Este estudo analisou 217 pacientes distribuídos nos Grupos Degeneração Discal e Grupo Controle. Foi coletado sangue periférico de todos os pacientes para a detecção dos polimorfismos do gene VEGF identificados por qPCR (rs699947, rs1570360, rs2010963, rs833061 e rs3025039). Todos os pacientes que apresentaram degeneração discal tiveram a confirmação por meio de ressonância magnética nuclear e avaliação do nível de degeneração do disco. Resultados: Todos os polimorfismos foram encontrados no equilíbrio de Hardy-Weinberg (p>0,05) na população estudada. A frequência genotípica para o Grupo Degeneração de Disco e do Grupo Controle foi rs699947 p=0,475, rs1570360 p=0,862, rs2010963 p=0,823, rs833061 p=0,596 e rs3025039 p=0,230. Para a análise do haplótipo, destacaram-se as composições CAGGC (p=0,094) e CCGGC (p=0,054). Conclusão: A correlação entre os polimorfismos do gene VEGF como preditor de risco para degeneração discal foi negativa na população estudada. No entanto, o VEGF possui grande região polimórfica, ativada por vários fatores catabólicos e metabólicos no processo de degeneração discal, que não está completamente elucidado.

Analysis of crucial molecules involved in herniated discs and degenerative disc disease

OBJECTIVES: Herniated discs and degenerative disc disease are major health problems worldwide. However, their pathogenesis remains obscure. This study aimed to explore the molecular mechanisms of these ailments and to identify underlying therapeutic targets. MATERIAL AND METHODS: Using the GSE23130 microarray datasets downloaded from the Gene Expression Omnibus database, differentially co-expressed genes and links were identified using the differentially co-expressed gene and link method with a false discovery rate ,0.25 as a significant threshold. Subsequently, the underlying molecular mechanisms of the differential co-expression of these genes were investigated using Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis. In addition, the transcriptional regulatory relationship was also investigated. RESULTS: Through the analysis of the gene expression profiles of different specimens from patients with these diseases, 539 differentially co-expressed genes were identified for these ailments. The ten most significant signaling pathways involving the differentially co-expressed genes were identified by enrichment analysis. Among these pathways, apoptosis and extracellular matrix-receptor interaction pathways have been reported to be related to these diseases. A total of 62 pairs of regulatory relationships between transcription factors and their target genes were identified as critical for the pathogenesis of these diseases. CONCLUSION: The results of our study will help to identify the mechanisms responsible for herniated discs and degenerative disc disease and provides a theoretical basis for further therapeutic study.

Snapshot of degenerative aging of porcine intervertebral disc: a model to unravel the molecular mechanisms

Larger animal models, such as porcine, have been validated as appropriate models of the human disc with respect to biomechanics and biochemistry. They are advantageous for research as the models are relatively straightforward to prepare and easily obtainable for research to perform surgical techniques. The intention of this study was to quantitatively analyze gene expression for collagen and proteoglycan components of the extracellular matrix and for collagenase (MMP-1) in porcine discs of varying ages (Newborn; 2-3weeks, Mature; 6-9 month, Older; 2-3 years). In this study, we observed that the cell number and GAG (glycosaminoglycan) formation dramatically decreased with aging. Also, gene expression in the annulus fibrosus (AF) and nucleus pulposus (NP) cells changed with aging. The level of MMP-1 mRNA increased with age and both type I, II collagens decreased with age. The level of aggrecan mRNA was highest in the mature group and decreased significantly with aging. In the mature group, MMP-1 expression was minimal compared to the newborn group. In AF cells, type II collagen was expressed at a high level in the mature group with a higher level of aggrecan, when aged NP showed a decrease in type II collagen. The model of IVD degeneration in the porcine disc shows many changes in gene expression with age that have been previously documented for human and may serve as a model for studying changes in IVD metabolism with age. We concluded that the porcine model is excellent to test hypotheses related to disc degeneration while permitting time-course study in biologically active systems.

Fatores genéticos e ambientais envolvidos na degeneração do disco intervertebral / Genetic and environmental factors involved on intervertebral disc degeneration

A etiologia da degeneração do disco intervertebral (DDI) ainda não está totalmente esclarecida. O gene do receptor da vitamina D (VDR) tem sido apontado como um dos possíveis envolvidos no surgimento das discopatias. Por outro lado, este estudo relaciona pela primeira vez, a participação dos genes das glutatião transferases M1 e T1 (GSTT1 e GSTM1), responsáveis pela inativação dos componentes do cigarro, na DDI. Foi extraído DNA de leucócitos de 66 pacientes e 88 controles, pareados por gênero e idade. O polimorfismo VDR-FokI foi amplificado por reação em cadeia da polimerase (PCR) seguido de restrição com a enzima FokI. Os polimorfismos das GSTT1/M1 foram determinados por meio da PCR multiplex. A história familial e a gravidade da doença se destacaram nos pacientes portadores do alelo f do gene VDR-FokI (P=0,000 e 0,0012, respectivamente). A idade de surgimento da doença mostrou-se precoce nos indivíduos com genótipo _/f (média de 26 anos). Foi encontrada associação do polimorfismo FokI com a degeneração precoce e gravidade da DDI, sendo que o hábito de fumar também interferiu nesse processo, independente da presença ou não do genótipo favorável para GSTT1/M1.

The etiology of intervertebral disc degeneration (IDD) has not been fully clarified yet. Vitamin D receptorÆs gene (VDR) has been suggested as one of the potential entities involved in disc pathologies onset. On the other hand, this study correlates, for the first time, glutathione transferases M1 and T1 genes (GSTT1 and GSTM1) participation, which are responsible for cigarette componentsÆ inactivation, in IDD. DNA was extracted from leukocytes of 66 patients and 88 controls, paired by gender and age. The VDR-Fokl polymorphism was amplified by polymerase chain reaction (PCR) followed by restriction with Fokl enzyme. GSTT1/M1 polymorphisms were determined by means of PCR multiplex. Family history and disease severity were highlighted in patients carrying the f allele of the VDR-Fokl gene (P=0.000 and 0.0012, respectively). The age at disease onset has shown to be early in individuals with _/f genotype (average 26 years old). A correlation was found between Fokl polymorphism and early degeneration and IDD severity, with smoking habit also interfering in this process, regardless of the presence or absence of a favorable genotype for GSTT1/M1.