Mechanisms of and treatments for alcohol-induced disc degeneration

PROJECT SUMMARY: The rapid increase in painful intervertebral disc (IVD) degeneration (IDD) makes it an urgent need to develop solutions for stopping IDD progression. IDD is associated with cell senescence, chronic inflammation, loss of IVD cellularity, matrix alterations, and changes in mechanical properties. In the United States, approximately 28.6 million adults have a diagnosis of alcohol use disorder (AUD), and AUD has been associated with chronic musculoskeletal pain, including back pain, and IDD-related surgical complications after spinal procedures. Chronic back pain increases the risk of greater alcohol consumption, and increased alcohol intake is associated with higher risk of IDD. Despite the high prevalence of painful IDD and AUD, no studies exist that link chronic alcohol consumption and IDD. The overall goal of this proposal is to identify this link by elucidating the mechanisms that drive IDD during chronic alcohol misuse and therapeutically halting IDD progression. Alcohol is known to cause accumulation of reactive oxygen species (ROS) and advanced glycation endproducts (AGEs), which is the most striking evidence of oxidative damage to the IVD and is known to cause IVD matrix stiffness. We previously showed that pioglitazone (PIO), a peroxisome proliferator-activated receptor gamma (PPAR) agonist and FDA approved drug, protects against ethanol (EtOH)-induced ROS accumulation by activating PPAR and decreasing the expression of NAPDH oxidase (NOX) 4 in alveolar macrophages. Here, we present exciting preliminary evidence that chronic alcohol consumption induces early degenerative changes by altering IVD morphology and stiffness. Aim 1 will establish the phenotype of chronic alcohol-induced IDD in mice. The effect of alcohol on IDD will be assessed for morphological, molecular, and biomechanical changes, as well as for pain. In vitro studies will evaluate the underlying pathways by exposing healthy human IVD cells to the EtOH metabolite, acetaldehyde. Effects on NOX4, ROS generation, cell senescence, and mitochondrial dysfunction will be determined molecularly and immunocytochemically and using an extracellular flux bioanalyzer. Aim 2 will test the therapeutic potential of PIO in stopping EtOH induced degenerative changes in human IVD cells using in vitro bulk-RNAseq, multiplex-ELISA, and immunocytochemistry. This project is highly significant because AUD and discogenic back pain are major burdens in the United States. New insights into mechanisms and treatments for IDD will combine mechanistic and translational studies. This study is conceptually innovative because the correlation between AUD and IDD has not been studied previously, and the use of an extracellular flux bioanalyzer to determine cell metabolic phenotype switching between glycolysis and oxidative phosphorylation in IVD cells is technically innovative. Outcomes will be impactful because PIO is an FDA approved drug and promising results can be readily translated to provide minimally-invasive treatments for people suffering from IDD, especially those with AUD.