Search

Study Design: Profiling proteins expressed in the nucleus pulposus (NP) of intervertebral discs (IVDs) in five different biological states. Purpose: To evaluate the molecular complexity of the collagen (COL) framework and its role in the health and disease of human IVDs. Overview of Literature: Changes in COL composition have been linked to degenerative disk disease (DDD). Despite the fact that humans have 28 different types of COLs, most of the literature focuses solely on COL-1 and COL-2. This study used high-end proteomic technology to examine the entire COL composition of the human IVD across fetal (developmental-FD), normal (healthy-ND), scoliotic (early degeneration-SD), herniated (degenerate-DH), and degenerated (DD) disk phenotypes. Methods: Forty NP tissues were snap-frozen in liquid nitrogen (-196°C) immediately before being subjected to proteomic and bioinformatic analyses from five different disk phenotypes (eight each). Results: Tandem mass spectrometric analysis revealed a total of 1,050 proteins in FDs, 1,809 in ND, 1,487 in SD, 1,859 in DH, and 1,538 in the DD group. Of 28 major collagens reported in the human body, this study identified 24 different collagens with 34 subtypes in NP. Fibril-forming collagens (COL-1, 2, and 11A1) and fibril-associated collagens with interrupted triple helices (COL-9A1, 12A1, and 14A1) were abundantly expressed in FDs, representing their role in the development of NP. Multiplexin (COL-15), a hybrid proteoglycan-collagen molecule, was discovered only in FDs. Degeneration was associated with COL2A1 downregulation and COL-10A1 upregulation. Conclusions: COL10 was discovered to be a new biomarker for disk degeneration. Besides COL-1 and 2, other important COLs (6, 9, 11, 12, 14, 15) with anabolic potential and abundant expression in the fetal phenotype could be investigated for tissue engineering and novel DDD therapy. [ABSTRACT FROM AUTHOR]

Study Design: Profiling proteins expressed in the nucleus pulposus of fetal intervertebral disc (IVD). Purpose: To evaluate the molecular complexity of fetal IVDs not exposed to mechanical, traumatic, inflammatory, or infective insults to generate improved knowledge on disc homeostasis. Overview of Literature: Low back pain is the most common musculoskeletal disorder, causing a significant reduction in the quality of life, and degenerative disc disorders mainly contribute to the increasing socioeconomic burden. Despite extensive research, the causative pathomechanisms behind degenerative disc disorders are poorly understood. Precise molecular studies on the intricate biological processes involved in maintaining normal disc homeostasis are needed. Methods: IVDs of nine fetal specimens obtained from medical abortions were used to dissect out the annulus fibrosus and nucleus pulposus under sterile operating conditions. Dissected tissues were transferred to sterile Cryovials and snap frozen in liquid nitrogen before transporting to the research laboratory for protein extraction and further liquid chromatography tandem mass spectrometry (LCMS/ MS) analysis. Collected data were further analyzed using Gene Functional Classification Tool in DAVID and STRING databases. Results: A total of 1,316 proteins were identified through LC-MS/MS analysis of nine fetal IVD tissues. Approximately 247 proteins present in at least four fetal discs were subjected to further bioinformatic analysis. The following 10 clusters of proteins were identified: collagens, ribosomal proteins, small leucine-rich proteins, matrilin and thrombospondin, annexins, protein disulfide isomerase family proteins and peroxiredoxins, tubulins, histones, hemoglobin, and prolyl 4-hydroxylase family proteins. Conclusions: This study provides fundamental information on the proteome networks involved in the growth and development of healthy fetal discs in humans. Systematic cataloging of proteins involved in various structural and regulatory processes has been performed. Proteins expressed most abundantly (collagen type XIV alpha 1 chain, biglycan, matrilin 1, and thrombospondin 1) in their respective clusters also elucidate the possibility of utilizing these proteins for potential regenerative therapies. [ABSTRACT FROM AUTHOR]

Objective: To catalog and characterize the proteome of normal human intervertebral disc (IVD). Methods: Nine magnetic resonance imaging (MRI) normal IVDs were harvested from 9 different brain dead yet alive voluntary organ donors and were subjected to electrospray ionization-liquid chromatography tandem mass spectrometry (ESI-LC-MS/MS) acquisition. Results: A total of 1,116 proteins were identified. Functional enrichment analysis tool DAVID ver. 6.8 categorized: extracellular proteins (38%), intracellular (31%), protein-containing complex (13%), organelle (9%), membrane proteins (6%), supramolecular complex (2%), and 1% in the cell junction. Molecular function revealed: binding activity (42%), catalytic activity (31%), regulatory activity (14%), and structural activity (7%). Molecular transducer, transporter, and transcription regulator activity together contributed to 6%. A comparison of the proteins obtained from this study to others in the literature showed a wide variation in content with only 3% of bovine, 5% of murine, 54% of human scoliotic discs, and 10.2% of discs adjacent to lumbar burst fractures common to our study of organ donors. Between proteins reported in scoliosis and lumbar fracture patients, only 13.51% were common, further signifying the contrast amongst the various MRI normal IVD samples. Conclusion: The proteome of “healthy” human IVDs has been defined, and our results show that proteomic data on IVDs obtained from scoliosis, fracture patients, and cadavers lack normal physiological conditions and should not be used as biological controls despite normal MRI findings. This questions the validity of previous studies that have used such discs as controls for analyzing the pathomechanisms of disc degeneration. [ABSTRACT FROM AUTHOR]

The accumulating evidence associating subclinical infection with degenerative disc disease (DDD) and the controversy of contamination vs infection mandates further understanding of the microbial activity in the disc and host-microbiome interaction. To utilize a novel approach of metabolomics to probe the presence of bacterial metabolites involved in colonization, survival and replication in human lumbar intervertebral discs (LIVD). An observational case-control study. Nucleus pulposus from the LIVD of three brain-dead voluntary organ donors (MRI normal and classified as controls) and of three patients undergoing surgery for degenerative disc disease (DDD) (cases) were utilized. To prove presence of live and metabolically active bacteria in intervertebral disc. Untargeted metabolite profiling was carried out in six discs (3 controls and 3 cases) after extraction using methanol: acetonitrile: water (2 2:1) solvent system and acquired through HPLC-MS/MS platform using C18 reversed-phase column. From the total IVD metabolome, microbial metabolites were filtered by mapping against HMDB, ChEBI, SigMol, Siderophore database, ecdmb database, and PaMet databases. Biological functions of the metabolites were then studied by MSEA pipeline from Metaboanalyst, and the enrichment ratio, p-value, and Variably Importance Projection scores (VIPS) of the metabolites calculated. Degeneration responsive changes in the abundance of the microbial metabolites were calculated based on the peak intensities between the control and cases. Mass spectrometry identified a total of 17601 and 15003 metabolites, respectively, in the control and diseased discs. Preliminary mapping of the above metabolites against HMDB indicated the multiple sources and of these, 64 metabolites were of microbial origin, accounting for 1.6% of the total IVD metabolome. Principle Component Analysis (PCA) and Orthogonal Partial Least Square-Discriminant Analysis (OPLSD-DA) showed distinct clustered patterns between control and disease, indicating a strong variation in concentration, peak and spectral values of the 64 metabolites between controls and cases. After exclusion of metabolites that were also associated with humans, drugs and food, 39 metabolites specific to bacteria were isolated. Nine were primary related to bacterial growth and survival, and the remaining 30 were secondary related to different environmental stress response activities. The three significant pathways (p 1.0) was found for nine metabolites which included (S)-14-methyilhexadecanoic acid related to P.acnes, 9-OxoODE, and 13-OxoODE related to gut flora, vibriobactin - a siderophore, tuberculosinol and iso-tuberculosinol, virulence factors of M.tuberculosis. There was also upregulation of autoinducer- 2, an important "Quorum sensing molecule" involved in bacterial cross-talk. We identified several bacterial-specific metabolites participating in pathways involved in bacterial growth, survival and cross-talk. These were found in both groups but upregulated in diseased discs. Presence of quorum sensing molecules and cell-cell interactions provides firm proof of colonization and growth. These findings indicate that bacterial presence is not mere contamination but a colonization with possible role in infection-mediated inflammaging in DDD. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]

The true understanding of aging and disc degeneration (DD) is still elusive. MRI has not helped our attempts to understand the health and disease status of the discs as it reflects mainly the end morphological changes and not the changes at a molecular level. Understanding degeneration at a molecular level through proteomics might allow differentiation from normal aging and also aid in the development of biomarkers for early diagnosis and preventive therapies. To utilize proteomics to understand the molecular basis of healthy, aging and degenerating discs and conclusively differentiate normal aging and degeneration. Proteomic analysis of human intervertebral disc samples. L4-L5 disc samples from three groups were acquired and subjected to proteomic analysis. Samples from individuals aged in the 2nd, 3rd, and 4th decades were used to represent young healthy discs (Group A). Those from MRI normal donors aged in the 5th, 6th and 7th decades represented normal aging (Group B). Five degenerated discs obtained from patients at surgery represented degeneration (Group C). The entire proteome map and alteration in protein expressions were further analyzed using bioinformatics analysis. This was a self-funded project. There were 84 common proteins. Specific proteins numbered 225 in A, 315 in B and 283 in C. By gene ontology biological process identification, Group A predominated with extracellular matrix organization, cytoskeletal structural and normal metabolic proteins. Group B differed in having additional basal expression of immune response, complement inhibitors and senescence proteins. Group C was different, with up regulation of proteins associated with oxidative stress response, positive regulators of apoptosis, innate immune response, complement activation and defense response to gram positive bacteria indicating ongoing inflammaging. Our study documented diverse proteome signatures between the young, aging and degenerating discs. Inflammaging was the main differentiation between normal biological aging and DD. Multiple inflammatory molecules unique to DD were identified, allowing the possibility of developing specific biomarkers for early diagnosis and thereby provide evidence-based metrics for preventive measures rather than surgical intervention and also to monitor progress of the disease. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]

Patients with Modic changes form a distinct clinical subset with reports of higher intensity of pain, poor clinical and surgical outcomes and higher incidence of recurrence. MC also is an independent risk factor for increased postoperative surgical site infection. This study aimed to investigate the biological changes at molecular level, in discs with Modic changes. Experimental analysis. Nucleus pulposus (NP) from 24 patients undergoing microdiscectomy for disc herniation [14 discs with Modic changes and 10 without Modic changes] were procured. The overall expression of proteins, biological processes, protein-protein and metabolite interactions were analyzed and compared. Host defense response proteins (HDRPs) and immunological pathways activated in patients with Modic changes were documented and analyzed. Label-free proteomic approach with stringent filters revealed a total of 208 proteins in Modic changes and 193 in non-Modic change groups. Forty-five proteins were specific to Modic changes; 30 to non-Modic changes and 163 common to both. Downregulated proteins in Modic changes belonged to components of extracellular matrix such as collagens (COL- 6A1, 6A2, 6A3, 11A1, 12A1, and 20A1), and proteoglycans (versican [VCAN], and biglycan [BGN]). Inflammatory molecules [plasminogen (PLG), angiogenin (ANG), fibroblast growth factor-binding protein 2 (FGFBP2), tetranectin (CLEC3B), cartilage acidic protein 1(CRTAC1), kininogen (KNG1), chitinase-3-like protein 2 (CHI3L2), and ferritin (FTL) were expressed only in the Modic changes group. The significantly altered pathways in Modic changes included Fc Fragment of IgG Receptor IIIa (FCGR3A)-mediated phagocytosis, regulation of Toll-like receptors (TLR) by endogenous ligand, neutrophil and platelet degranulation. 50 HDRPs were identified in the study, 14 of which were specific to Modic changes and included acute phase reactants, antimicrobial peptides, complement cascade proteins, inflammatory molecule and stress response proteins. Metabolite-protein interaction analysis revealed a significant interaction between 19 proteins, specifically involving ubiquitin mediating proteasome degradative pathway and an association with the metabolite-glutamic acid in the Modic changes group. Accumulation of glutamic acid in Modic changes discs was confirmed by quantitative amino acid analysis using High-performance liquid chromatography. Our study confirms that Modic changes represent an intense inflammatory status due to activation of host defense response and immunological pathways. Downstream effects leading to ubiquitin mediated proteasomal degradation of ECM proteins and the resulting metabolites such as glutamic acid could cause excessive pain and needs further investigation. Clinical Significance: We have documented the expression of inflammatory molecules, immune mechanisms and host defense response proteins which throw molecular insights into the pathological mechanisms of Modic changes. Further, ubiquitin mediated proteasomal degradation and accumulation of glutamate in discs with Modic changes might serve as targets for molecular therapy. This abstract does not discuss or include any applicable devices or drugs. [ABSTRACT FROM AUTHOR]