Characterization of metabolites determined by means of 1H HR MAS NMR in intervertebral disc degeneration

Nutrient metabolism of the nucleus pulposus: A literature review

Cells take in, consume, and synthesize nutrients for numerous physiological functions. This includes not only energy production but also macromolecule biosynthesis, which will further influence cellular signaling, redox homeostasis, and cell fate commitment. Therefore, alteration in cellular nutrient metabolism is associated with pathological conditions. Intervertebral discs, particularly the nucleus pulposus (NP), are avascular and exhibit unique metabolic preferences. Clinical and preclinical studies have indicated a correlation between intervertebral degeneration (IDD) and systemic metabolic diseases such as diabetes, obesity, and dyslipidemia. However, a lack of understanding of the nutrient metabolism of NP cells is masking the underlying mechanism. Indeed, although previous studies indicated that glucose metabolism is essential for NP cells, the downstream metabolic pathways remain unknown, and the potential role of other nutrients, like amino acids and lipids, is understudied. In this literature review, we summarize the current understanding of nutrient metabolism in NP cells and discuss other potential metabolic pathways by referring to a human NP transcriptomic dataset deposited to the Gene Expression Omnibus, which can provide us hints for future studies of nutrient metabolism in NP cells and novel therapies for IDD.

A protocol for recruiting and analyzing the disease-oriented Russian disc degeneration study (RuDDS) biobank for functional omics studies of lumbar disc degeneration

Lumbar intervertebral disc degeneration (DD) disease is one of the main risk factors for low back pain and a leading cause of population absenteeism and disability worldwide. Despite a variety of biological studies, lumbar DD is not yet fully understood, partially because there are only few studies that use systematic and integrative approaches. This urges the need for studies that integrate different omics (including genomics and transcriptomics) measured on samples within a single cohort. This protocol describes a disease-oriented Russian disc degeneration study (RuDDS) biobank recruitment and analyses aimed to facilitate further omics studies of lumbar DD integrating genomic, transcriptomic and glycomic data. A total of 1,100 participants aged over 18 with available lumbar MRI scans, medical histories and biological material (whole blood, plasma and intervertebral disc tissue samples from surgically treated patients) will be enrolled during the three-year period from two Russian clinical centers. Whole blood, plasma and disc tissue specimens will be used for genotyping with genome-wide SNP-arrays, glycome profiling and RNA sequencing, respectively. Omics data will be further used for a genome-wide association study of lumbar DD with in silico functional annotation, analysis of plasma glycome and lumbar DD disease interactions and transcriptomic data analysis including an investigation of differential expression patterns associated with lumbar DD disease. Statistical tests applied in each of the analyses will meet the standard criteria specific to the attributed study field. In a long term, the results of the study will expand fundamental knowledge about lumbar DD development and contribute to the elaboration of novel personalized approaches for disease prediction and therapy. Additionally to the lumbar disc degeneration study, a RuDDS cohort could be used for other genetic studies, as it will have unique omics data.

Trial registration numberNCT04600544.

Taurine attenuates ER stress‑associated apoptosis and catabolism in nucleus pulposus cells

Nucleus pulposus (NP) apoptosis and subsequent excessive degradation of the extracellular matrix (ECM) are key pathological characteristics of intervertebral disc degeneration (IDD). The present study aims to examine the signaling processes underlying the effects of taurine on IDD, with specific focus on endoplasmic reticulum (ER) stress-mediated apoptosis and ECM degradation, in NP cells. To clarify the role of taurine in IDD, NP cells were treated with various concentrations of taurine and IL-1β or thapsigargin (TG). Cell Counting Kit-8, western blotting, TUNEL, immunofluorescence assays and reverse transcription-quantitative PCR were applied to measure cell viability, the expression of ER stress-associated proteins (GRP78, CHOP and caspase-12), apoptosis and the levels of metabolic factors associated with ECM (MMP-1, 3, 9, ADAMTS-4, 5 and collagen II), respectively. Taurine was found to attenuate ER stress and prevent apoptosis in NP cells induced by IL-1β treatment. Additionally, taurine significantly decreased the expression of ER stress-activated glucose regulatory protein 78, C/EBP homologous protein and caspase-12. TUNEL results revealed that taurine decreased the number of apoptotic TG-treated NP cells. TG-treated NP cells also exhibited characteristics of increased ECM degradation, supported by observations of increased MMP-1, MMP-3, MMP-9 and A disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS)-4 and ADAMTS-5 expression in addition to decreased collagen-II expression. However, taurine treatment significantly reversed all indicators of excessive ECM catabolism aforementioned. These data suggest that taurine can mediate protection against apoptosis and ECM degradation in NP cells by inhibiting ER stress, implicating therapeutic potential for the treatment of IDD.

Protocol for parallel proteomic and metabolomic analysis of mouse intervertebral disc tissues

The comprehensiveness of data collected by "omics" modalities has demonstrated the ability to drastically transform our understanding of the molecular mechanisms of chronic, complex diseases such as musculoskeletal pathologies, how biomarkers are identified, and how therapeutic targets are developed. Standardization of protocols will enable comparisons between findings reported by multiple research groups and move the application of these technologies forward. Herein, we describe a protocol for parallel proteomic and metabolomic analysis of mouse intervertebral disc (IVD) tissues, building from the combined expertise of our collaborative team. This protocol covers dissection of murine IVD tissues, sample isolation, and data analysis for both proteomics and metabolomics applications. The protocol presented below was optimized to maximize the utility of a mouse model for "omics" applications, accounting for the challenges associated with the small starting quantity of sample due to small tissue size as well as the extracellular matrix-rich nature of the tissue.

Applications of high-resolution magic angle spinning MRS in biomedical studies II-Human diseases

High-resolution magic angle spinning (HRMAS) MRS is a powerful method for gaining insight into the physiological and pathological processes of cellular metabolism. Given its ability to obtain high-resolution spectra of non-liquid biological samples, while preserving tissue architecture for subsequent histopathological analysis, the technique has become invaluable for biochemical and biomedical studies. Using HRMAS MRS, alterations in measured metabolites, metabolic ratios, and metabolomic profiles present the possibility to improve identification and prognostication of various diseases and decipher the metabolomic impact of drug therapies. In this review, we evaluate HRMAS MRS results on human tissue specimens from malignancies and non-localized diseases reported in the literature since the inception of the technique in 1996. We present the diverse applications of the technique in understanding pathological processes of different anatomical origins, correlations with in vivo imaging, effectiveness of therapies, and progress in the HRMAS methodology.

Assessing the correlation between the degree of disc degeneration on the Pfirrmann scale and the metabolites identified in HR-MAS NMR spectroscopy

OBJECTIVE

The objective of this study is to assess the correlation between the degree of degeneration of lumbar discs according to the Pfirrmann classification system and the concentrations of metabolites determined by means of 1H high-resolution magic angle spinning nuclear magnetic resonance (1H HR MAS NMR) spectroscopy.

MATERIALS AND METHODS

Twenty-six human intervertebral lumbar discs that were operated on due to degenerative disease were analyzed. Routine preoperative 1.5T, T2-weighed magnetic resonance (MR) images were used to classify the cases according to the Pfirrmann classification system. In all the cases, during microdiscectomy, the fragments of the annulus fibrosus and nucleus pulposus were harvested and their metabolic profile was examined by means of 1H HR MAS. The grades of disc degeneration on the Pfirrmann scale were correlated with the metabolite concentrations.

RESULTS

Spectral analyses of the intervertebral discs with Pfirrmann grades IV and V demonstrated significantly higher concentrations of creatine, glycine, hydroxyproline, alanine, leucine, valine, acetate, isoleucine, α,β-glucose, and myo-inositol, and a lower intensity of the N-acetyl peak of chondroitin sulfate, compared to the spectra with Pfirrmann grade III.

CONCLUSION

Our results demonstrate correlations between metabolite concentrations and the degree of lumbar disc degeneration assessed using the Pfirrmann grading system and provide another step toward the potential use of in vivo MR spectroscopy for investigation of biomarkers in lumbar disc degeneration.