Effect of hyperlipidaemia to accelerate intervertebral disc degeneration in the injured rat caudal disc model

Evaluating the causal effect of atherosclerosis on the risk of intervertebral disc degeneration

Background

Intervertebral disc degeneration (IDD) and atherosclerosis are two common age-related conditions that can cause significant morbidity. While previous studies have suggested an association between the two conditions, the nature of this association remains unclear.

Methods

We used Mendelian randomization (MR) to investigate the causal relationship between IDD and atherosclerosis. We identified genetic variants associated with IDD using summary statistics from a large genome-wide association study (GWAS). These variants were then used as instrumental variables to infer causal relationships with atherosclerosis in summary statistics from a separate GWAS.

Results

Our MR analysis provided evidence for a causal relationship between IDD and atherosclerosis. We found that the genetic predisposition to atherosclerosis was associated with a higher risk of IDD (odds ratio [OR] = 3.55, 95% confidence interval [CI]: 1.07-11.74, p = 0.04). The IVW estimates were consistent with the observational findings and other robust MR methods. Sensitivity analyses suggested that our findings were robust to potential sources of bias.

Conclusions

Our study provides evidence for a causal link between IDD and atherosclerosis, suggesting that interventions targeting atherosclerosis could have potential benefits for reducing the risk of IDD. Further research is needed to explore the underlying mechanisms that link these two conditions and to investigate potential therapeutic interventions.

Association of Hyperlipidemia With Perioperative Complications in Posterior Cervical Spine Fusion: A Comparative Retrospective Study

STUDY DESIGN

A retrospective database study.

OBJECTIVES

The purpose of the current study was to investigate the impact of hyperlipidemia (HLD) on the incidence of perioperative complications associated with posterior cervical spine fusion (PCF).

BACKGROUND

HLD is a very common disease that leads to atherosclerosis. Therefore, it can cause fatal diseases as well as lifestyle-related diseases. The possible impact of HLD on outcomes after PCF has not yet been investigated.

METHODS

Patients with cervical degeneration underwent initial PCF from 2010 through the third quarter of 2020 using the MSpine subset of the PearlDiver Patient Record Database. The incidence of perioperative complications was queried using relevant ICD-9, 10, and CPT codes. χ 2 analysis was performed in age-, sex-, and Charlson Comorbidity Index (CCI)-matched populations to compare between non-HLD and HLD patients in each single-level and multilevel PCF.

RESULTS

Through propensity score matching, 1600 patients each in the HLD and non-HLD groups were analyzed in the single-level PCF, 6855 patients were analyzed in the multilevel PCF were analyzed. The comorbidity of HLD significantly decreased the incidence of respiratory failure in single-level PCF (OR=0.58, P <0.01). In the multilevel PCF, the presence of HLD increased the incidence of cervicalgia (OR=1.26, P =0.030). On the contrary, the incident of spinal cord injury (OR=0.72, P <0.01), dysphagia (OR=0.81, P =0.023), respiratory failure (OR=0.85, P =0.030), pneumonia (OR=0.70, P =0.045), neurological bladder (OR=0.84, P =0.041), and urinary tract infection (OR=0.85, P =0.021) in the HLD group were significantly lower than those in non-HLD group.

CONCLUSIONS

In the current study, the presence of HLD significantly increased the incidence of postoperative cervicalgia in multilevel PCF. On the other hand, the incidence of some complications was significantly decreased with HLD. Further studies are needed taking into account other factors such as the treatment of HLD, its efficacy, and intraoperative events.

LEVEL OF EVIDENCE

Level III.

Cytokine Imbalance as a Biomarker of Intervertebral Disk Degeneration

The intervertebral disk degeneration (IDD) and its associated conditions are an important problem in modern medicine. The onset of IDD may be in childhood and adolescence in patients with a genetic predisposition. IDD progresses with age, leading to spondylosis, spondylarthrosis, intervertebral disk herniation, and spinal stenosis. The purpose of this review is an attempt to summarize the data characterizing the patterns of production of pro-inflammatory and anti-inflammatory cytokines in IDD and to appreciate the prognostic value of cytokine imbalance as its biomarker. This narrative review demonstrates that the problem of evaluating the contribution of pro-inflammatory and anti-inflammatory cytokines to the maintenance or alteration of cytokine balance may be a new key to unlocking the mystery of IDD development and new therapeutic strategies for the treatment of IDD in the setting of acute and chronic inflammation. The presented data support the hypothesis that cytokine imbalance is one of the most important biomarkers of IDD.

A novel rat model of vertebral inflammation-induced intervertebral disc degeneration mediated by activating cGAS/STING molecular pathway

In this study, we describe a new rat model of vertebral inflammation-induced caudal intervertebral disc degeneration (VI-IVDD), in which IVD structure was not damaged and controllable segment and speed degeneration was achieved. VI-IVDD model was obtained by placing lipopolysaccharide (LPS) in the caudal vertebral bodies of rats. Rat experimental groups were set as follows: normal control group, group with a hole drilled in the middle of vertebral body and not filled with LPS (Blank group), group with a hole drilled in the middle of vertebral body and filled with LPS (Mid group), and group with hole drilled in the vertebral body in proximity of IVD and filled with LPS (NIVD group). Radiological results of VI-IVDD rats showed a significant reduction in the intervertebral space height and decrease in MRI T2 signal intensity. Histological stainings also revealed that the more the nucleus pulposus and endplate degenerated, the more the annulus fibrosus structure appeared disorganized. Immunohistochemistry analysis demonstrated that the expression of Aggrecan and collagen-II decreased, whereas that of MMP-3 increased in Mid and NIVD groups. Abundant local production of pro-inflammatory cytokines was detected together with increased infiltration of M1 macrophages in Mid and NIVD groups. Apoptosis ratio remarkably enhanced in Mid and NIVD groups. Interestingly, we found a strong activation of the cyclic GMP-AMP synthase /stimulator of interferon gene signalling pathway, which is strictly related to inflammatory and degenerative diseases. In this study, we generated a new, reliable and reproducible IVDD rat model, in which controllable segment and speed degeneration was achieved.

Drp1-mediated mitochondrial fission is involved in oxidized low-density lipoprotein-induced AF cella poptosis

This study aimed to assess the negative effect of oxidized low-density lipoprotein (oxLDL) on annulus fibrosus (AF) cells and decipher the mechanism of action of the process. After treating AF cells with various concentrations (0, 25, 50, 100, and 200 μg/mL) of oxLDL for 24 and 48 hours, their viability was evaluated using cell counting kit-8 and live/dead staining. The percentage of AF cell death was determined with Annexin V/propidium iodide apoptosis staining. The expression of proteins related to the mitochondrial apoptosis pathway was determined using Western blot. Additionally, mitochondrial membrane potential (MMP) and intracellular reactive oxygen species (ROS) were assessed with JC-1 staining and dichlorodihydrofluorescein diacetate ormitoSOX probes, respectively. Mitochondrial morphology was observed with a transmission electron microscope. After treatment with oxLDL, AF cell viability decreased, pro-apoptosis proteins (such as Bax, cleaved caspase-9, and cleaved caspase-3) increased, and anti-apoptosis proteins (Bcl-2) declined. Excessive ROS and diminished MMP were also detected during this process, as were enhanced mitochondrial fission and augmented Drp1 expression. Furthermore, knocking down the expression of Drp1 rescued oxLDL-induced AF cell death. Collectively, these results suggest that oxLDL induces AF cell death through a mitochondria-related pathway. Enhanced mitochondrial fission was involved in oxLDL-induced AF cell death. Targeting Drp1, a target for regulating the process of mitochondrial fission, may be a feasible strategy for preventing intervertebral disc degeneration in hyperlipidemia.