Lumbar intervertebral disc mRNA sequencing identifies the regulatory pathway in patients with disc herniation and spondylolisthesis

Here, we show results from next generation RNA sequencing (RNA-seq) on mRNA isolated from 10 human nucleus pulposus (NP) samples of lumbar degenerated discs (DH and DS; n=5 for each tissue) and other musculoskeletal tissues (Bone, cartilage, growth plate, and muscle; n=7 for each tissue). Pathway and network analyses based on gene ontology (GO) terms were used to identify the biological functions of differentially expressed mRNAs. A total of 701 genes were found to be significantly upregulated in lumbar NP tissue compared to other musculoskeletal tissues. These differentially expressed mRNAs were primarily involved in DNA damage, immunity and G1/S transition of mitotic cell cycle. Interestingly, DH-specific signaling genes showed major network in chemotactic (e.g., CXCL10, CXCL11, IL1RL2 and IL6) and matrix-degrading pathway (e.g., MMP16, ADAMTSL1, 5, 8, 12, and 15), while DS-specific signaling genes were found to be those involved in cell adhesion (e.g., CDH1, EPHA1and EFNA2) and inflammatory cytokines (e.g., CD19, CXCL5, CCL24, 25 and XCL2). Our findings provide new leads for therapeutic drug discovery that would permit optimization of medical or pharmacological intervention for cases of lumbar DDD. A total of 10 intervertebral disc specimens were collected for research use from 10 adult patients undergoing lumbar discectomy. Patients in this study underwent surgery for the treatment of symptomatic degenerative disk disease presenting with disc herniation or with spondylolisthesis.The specimens used in this investigation were collected under institutional review board approved protocols (IRB# 14-008177).