Elevated inflammatory gene expression in intervertebral disc tissues in mice with ADAM8 inactivated

Tnfa , Il6 , Cxcl1 , and Adam8 Genes Are the Early Markers After Mouse Tail Intervertebral Disc Injury

OBJECTIVES

The early molecular events after intervertebral disc injury remain unclear. In this study, we aimed to compare inflammatory markers from 1 day to 4 wks after injury to have a comprehensive understanding of the intervertebral disc response to injury.

DESIGN

Mouse tail intervertebral disc injury was induced by a needle puncture. Inflammatory marker gene expression and morphological changes were recorded at 1 day, 1 wk, and 4 wks after injury.

RESULTS

Tnfa , Il6 , and Cxcl1 gene expression peaked at day 1 post-needle puncture of the mouse intervertebral disc, Adam8 gene expression peaked at 1-wk time point, while Tipe2 gene expression was upregulated at week 4 postinjury. F4/80 positive cells, likely to be macrophages, are present as early as day 1 in the injured intervertebral discs and consistently present at week 4 postinjury. Loss of Safranin O staining and increased histological scores of the injured intervertebral discs are consistent with progressive degeneration after injury.

CONCLUSIONS

Inflammatory cytokines including Tnfa precede Tipe2 , suggesting that Tipe2 is likely induced by Tnfa . Upregulation of Adam8 and Cxcl1 gene expression persisted at week 4, suggesting that they play a role in the transition to chronic phase of intervertebral disc degeneration.

Serum antioxidant enzymes in spinal stenosis patients with lumbar disc herniation: correlation with degeneration severity and spinal fusion rate

OBJECTIVE

To determine whether superoxide dismutase (SOD) and glutathione reductase (GR) correlated with the intervertebral disc degeneration (IDD) severity and the postoperative spinal fusion rate in lumbar spinal stenosis patients accompanied with lumbar disc herniation.

METHODS

This retrospective study investigated 310 cases of posterior lumbar decompression and fusion. The cumulative grade was calculated by adding the pfirrmann grades of all the lumbar discs. Subjects were grouped based on the median cumulative grade. Logistic regression was used to determine the associations among the demographical, clinical, and laboratory indexes and severe degeneration and fusion. The receiver operating characteristic (ROC) curve was performed to measure model discrimination, and Hosmer-Lemeshow (H-L) test was used to measure calibration.

RESULTS

SOD and GR levels were significantly lower in the severe degeneration group (cumulative grade > 18) than in the mild to moderate degeneration group (cumulative grade ≤ 18). Furthermore, the SOD and GR concentrations of the fusion group were significantly higher than that of the non-fusion group (p < 0.001 and p = 0.006). The multivariate binary logistic models revealed that SOD and GR were independently influencing factors of the severe degeneration (OR: 0.966, 95%CI: 0.950-0.982, and OR: 0.946, 95%CI: 0.915-0.978, respectively) and non-fusion (OR: 0.962; 95% CI: 0.947-0.978; OR: 0.963; 95% CI: 0.933-0.994). The models showed excellent discrimination and calibration. Trend analysis indicated that the levels of SOD and GR tended to decrease with increasing severity (p for trend < 0.001 and 0.003). In addition, it also revealed that SOD provided protection from non-fusion in a concentration-dependent manner (p for trend < 0.001). However, GR concentration-dependent effects were not apparent (p for trend = 0.301).

CONCLUSION

High serum SOD and GR levels are associated with a better fusion prognosis and a relief in degeneration severity.

Recent advances in the repair of degenerative intervertebral disc for preclinical applications

The intervertebral disc (IVD) is a load-bearing, avascular tissue that cushions pressure and increases flexibility in the spine. Under the influence of obesity, injury, and reduced nutrient supply, it develops pathological changes such as fibular annulus (AF) injury, disc herniation, and inflammation, eventually leading to intervertebral disc degeneration (IDD). Lower back pain (LBP) caused by IDD is a severe chronic disorder that severely affects patients' quality of life and has a substantial socioeconomic impact. Patients may consider surgical treatment after conservative treatment has failed. However, the broken AF cannot be repaired after surgery, and the incidence of re-protrusion and reoccurring pain is high, possibly leading to a degeneration of the adjacent vertebrae. Therefore, effective treatment strategies must be explored to repair and prevent IDD. This paper systematically reviews recent advances in repairing IVD, describes its advantages and shortcomings, and explores the future direction of repair technology.

In vivo Mouse Intervertebral Disc Degeneration Models and Their Utility as Translational Models of Clinical Discogenic Back Pain: A Comparative Review

Low back pain is a leading cause of disability worldwide and studies have demonstrated intervertebral disc (IVD) degeneration as a major risk factor. While many in vitro models have been developed and used to study IVD pathophysiology and therapeutic strategies, the etiology of IVD degeneration is a complex multifactorial process involving crosstalk of nearby tissues and systemic effects. Thus, the use of appropriate in vivo models is necessary to fully understand the associated molecular, structural, and functional changes and how they relate to pain. Mouse models have been widely adopted due to accessibility and ease of genetic manipulation compared to other animal models. Despite their small size, mice lumbar discs demonstrate significant similarities to the human IVD in terms of geometry, structure, and mechanical properties. While several different mouse models of IVD degeneration exist, greater standardization of the methods for inducing degeneration and the development of a consistent set of output measurements could allow mouse models to become a stronger tool for clinical translation. This article reviews current mouse models of IVD degeneration in the context of clinical translation and highlights a critical set of output measurements for studying disease pathology or screening regenerative therapies with an emphasis on pain phenotyping. First, we summarized and categorized these models into genetic, age-related, and mechanically induced. Then, the outcome parameters assessed in these models are compared including, molecular, cellular, functional/structural, and pain assessments for both evoked and spontaneous pain. These comparisons highlight a set of potential key parameters that can be used to validate the model and inform its utility to screen potential therapies for IVD degeneration and their translation to the human condition. As treatment of symptomatic pain is important, this review provides an emphasis on critical pain-like behavior assessments in mice and explores current behavioral assessments relevant to discogenic back pain. Overall, the specific research question was determined to be essential to identify the relevant model with histological staining, imaging, extracellular matrix composition, mechanics, and pain as critical parameters for assessing degeneration and regenerative strategies.