Detection of apoptosis and matrical degeneration within the intervertebral discs of rats due to passive cigarette smoking

Analysis of Nicotine Toxicity and Mechanisms of Senescence in Nucleus Pulposus Cells Using Network Toxicology and Molecular Docking Technique

Aim

Through the use of network toxicology, the research sought to determine whether cellular senescence and associated molecular mechanisms in nicotine-induced intervertebral disc degeneration (IVDD) were potentially harmful.

Methods

The primary chemical structure and 105 targets of action of nicotine were determined by using the Swiss Target Prediction, Cell Age, and PubChem databases. 855 IVDD senescence genes were found using the GEO and Cell Age datasets.

Results

After additional screening and Cytoscape development, 9 key targets were identified. Additionally, these targets' co-expression pattern analysis and protein interactions were confirmed to be identical. The core targets of nicotine-induced IVDD cellular senescence were found to be primarily enriched in the positive regulation of cell proliferation, telomere shortening, histone acetylation, and cellular senescence-related processes, according to gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG). The KEGG signaling pathway also made it clear that the Apelin signaling route, nicotinate and nicotinamide metabolism, cell cycle, and apoptosis are all strongly linked to nicotine-induced IVDD cellular senescence. We chose four genes associated with the cellular senescence pathway-HDAC1, HDAC4, and NAMPT, MYLK-for molecular docking with the toxic substance nicotine. The findings validated nicotine's strong affinity for the primary targets.

Conclusion

All things considered, the current research indicates that nicotine may contribute to cellular senescence in IVDD via controlling the histone deacetylation process, telomere shortening, the Apelin signaling pathway, and pathways linked to the metabolism of nicotinate and nicotinamide. The theoretical foundation for investigating the molecular mechanisms of nicotine-induced senescence in IVDD is established.

Engineering Intervertebral Disc Regeneration: Biomaterials, Cell Sources and Animal Models

Intervertebral disc (IVD) degeneration is an age-related problem triggering chronic spinal issues, such as low back pain and IVD herniation. Standard surgical treatment for such spinal issues is the removal of the degenerated or herniated IVD and fusion of adjacent vertebrae to stabilise the joint and locally decompress the spinal cord and/or nerve roots to relieve pain. However, a key challenge of current surgical strategies is the increasing risk of adjacent segment degeneration due to the disruption of native biomechanics of the functional spinal unit, dominated by the loss of the IVD. In the past two decades, research has focused on developing a number of bioengineering approaches to repair and regenerate the IVD; in particular, tissue engineering of the IVD, using bioscaffolds and stem cells represents a promising area. This review highlights the current tissue engineering approaches utilising biomaterials, animal models and cell sources for IVD regeneration and discusses future opportunities.

Endplate remodeling: a key indicator of cigarette smoke exposure-induced intervertebral disc degeneration in a male rat model

Recent clinical studies have established a strong association between cigarette smoking and degenerative disc disease. Both in vitro and in vivo research indicated that cigarette smoke disrupts cellular homeostasis in the intervertebral disc (IVD), leading to spatiotemporal remodeling of the extracellular matrix, with a notable reduction in solute diffusivity within the cartilage endplate (CEP). As the CEP serves as a critical mechanical barrier and solute diffusion pathway for the IVD, both roles can be compromised by pathological changes in the tissue. This underscores the need for a more comprehensive examination of endplate remodeling during IVD degeneration, particularly in the context of cigarette smoking and cessation. The objective of this study was to perform a quantitative analysis of the structure-material property relationship changes in the endplate at tissue and cellular levels to determine how endplate mineralization progresses during IVD degeneration in the context of cigarette smoke exposure and cessation, using our previously developed Sprague-Dawley rat model. Our results indicate that cigarette smoke exposure-induced endplate remodeling is characterized by a higher CEP histological grade, increased aberrant CEP calcification level, and elevated bony endplate surface flatness score, all of which correlated with an accelerated chondrocyte cell life cycle. Smoke cessation alone was insufficient to reverse the mineralization progression in the endplate. Principal component analysis further identified alterations in endplate morphometry at the tissue level and disruptions in the chondrocyte life cycle at cellular level as key markers of degenerative remodeling. These findings establish endplate remodeling as a key indicator of smoke exposure-induced IVD degeneration and inform the development of novel therapeutic strategies aimed at preserving or improving disc health.

Effect of cigarette smoke exposure and cessation on regional diffusion properties in rat intervertebral discs

Background

Cigarette smoking is a recognized risk factor for orthopedic disorders, particularly intervertebral disc (IVD) degenerative disease. However, the IVD pathophysiology, especially the spatial-temporal remodeling progression in the context of cigarette smoking, remains unclear. This study aimed to address this knowledge gap through a quantitative assessment of IVD structural composition and diffusion properties using a Sprague-Dawley rat model.

Methods

Twenty-four rats were divided into control and smoke exposure cohorts, each with two sub-groups of six rats. One smoke exposure sub-group was sacrificed after 2 months of daily cigarette smoke exposure in a custom smoking apparatus, while the other was sacrificed after an additional 5 months of smoke cessation. The control groups were age-matched to the smoke exposure groups. A fluorescent recovery after photobleaching (FRAP) technique was used to determine solute diffusivities and multi-photon excitation (MPE) imaging was performed to characterize structural changes in the annulus fibrosus (AF), nucleus pulposus (NP), and cartilage endplate (CEP).

Results

A decrease in diffusivity was observed in the CEP and the AF (radial direction only) after 2 months of smoke exposure. MPE imaging showed aberrant CEP calcification and reduced AF radial collagen fiber bundle diameter, suggesting that the IVD exhibits regionally dependent structural remodeling due to smoke exposure. Furthermore, the smoke cessation group showed deteriorating alterations of structure and diffusivities in all three-disc regions, including the NP, indicating that five-month smoke cessation alone didn't reverse the progression of IVD degenerative remodeling during aging.

Conclusion

This study advances the understanding of IVD pathophysiology in the context of cigarette smoke exposure and cessation, laying the groundwork for potential earlier diagnosis and optimized interventions.

How to spot the recurring lumbar disc? Risk factors for recurrent lumbar disc herniation (rLDH) in adult patients with lumbar disc prolapse: a systematic review and meta-analysis

Despite a fast-growing evidence-base examining the relationship of certain clinical and radiological factors such as smoking, BMI and herniation-type with rLDH, there remains much debate around which factors are clinically important. We conducted a systematic review and meta-analysis to identify risk factors for recurrent lumbar disc herniation (rLDH) in adults after primary discectomy. A systematic literature search was carried out using Ovid-Medline, EMBASE, Cochrane library and Web of Science databases from inception to 23rd June-2022. Observational studies of adult patients with radiologically-confirmed rLDH after ≥3 months of the initial surgery were included, and their quality assessed using the Quality-In-Prognostic-Studies (QUIPS) appraisal tool. Meta-analyses of univariate and multivariate data and a sensitivity-analysis for rLDH post-microdiscectomy were performed. Twelve studies (n=4497, mean age:47.3; 34.5% female) were included, and 11 studies (n=4235) meta-analysed. The mean follow-up was 38.4 months. Mean recurrence rate was 13.1% and mean time-to-recurrence was 24.1 months (range: 6-90 months). Clinically, older age (OR:1.04, 95%CI:1.00-1.08, n=1014), diabetes mellitus (OR:3.82, 95%CI:1.58-9.26, n=2330) and smoking (OR:1.80, 95%CI:1.03- 3.14, n=3425) increased likelihood of recurrence. Radiologically, Modic-change type-2 (OR:7.93, 95%CI:5.70-11.05, n=1706) and disc extrusion (OR:12.23, 95%CI:8.60-17.38, n=1706) increased likelihood of recurrence. The evidence did not support an association between rLDH and sex; BMI; occupational labour/driving; alcohol-consumption; Pfirmann- grade, or herniation-level. Older patients, smokers, patients with diabetes, those with type-2 Modic-changes or disc extrusion are more likely to experience rLDH. Higher quality studies with robust adjustment of confounders are required to determine the clinical bearing of all other potential risk factors for rLDH.

Environmental polycyclic aromatic hydrocarbon exposure is associated with low back pain

Several studies have assessed the influence of several often-ignored environmental factors on low back pain (LBP), but the effects of environmental polycyclic aromatic hydrocarbon (PAH) exposure on LBP are unclear. During the 2001-2004 cycle of the National Health and Nutrition Examination Survey (NHANES), our study was given to a representative sample of US participants older than 20 (N = 2743). Environmental PAH exposure was calculated using urinary PAH metabolite concentrations. Weighted logistic regression was performed to assess the connection between PAH levels and LBP, with mediation analysis utilised to explore the underlying mechanism. Levels of 1-hydroxynaphthalene (1-OHNa), 2-hydroxynaphthalene (2-OHNa) and total PAHs had a statistically significant positive association with LBP. The odds ratios per 1-unit increase for log-transformed levels of urinary 1-OHNa, 2-OHNa, and total PAHs with LBP were 1.01 (95% CI 1.02-1.19), 1.19 (95% CI 1.04-1.36) and 1.16 (95% CI 1.03-1.32), respectively. The results revealed a strong dose-response association between 1-OHNa, 2-OHNa, total PAHs, and LBP risk. Subgroup analysis indicated that 2&3-OHPh may increase the risk of LBP in the lower family income subgroup. Gamma-glutamyl transaminase (GGT), known as a biomarker of oxidative stress, was strongly related to PAHs. The relationship between total PAHs and LBP was mediated in part by GGT. Our study demonstrates associations between environmental PAH exposure and LBP that need more research to determine the precise effects of various PAH compounds on LBP.

Consensus statement on smoking cessation in patients with pain

Smoking is closely associated with the development of various cancers and tobacco-related illnesses such as cardiovascular and respiratory disorders. However, data are scarce on the relationship between smoking and both acute and chronic pain. In addition to nicotine, tobacco smoke contains more than 4000 different compounds. Although nicotine is not the sole cause of smoking-induced diseases, it plays a critical role in pain-related pathophysiology. Despite the acute analgesic effects of nicotine, long-term exposure leads to tolerance and increased pain sensitivity due to nicotinic acetylcholine receptor desensitization and neuronal plastic changes. The purpose of smoking cessation interventions in smoking patients with pain is primarily not only to reduce their pain and associated limitations in activities of daily living, but also to improve the outcomes of underlying pain-causing conditions and reduce the risks of tobacco-related disorders. This statement aims to summarize the available evidence on the impact of smoking on pain and to inform medical professionals of the significance of smoking cessation in patients with pain.

The effects of smoking on clinical and structural outcomes after rotator cuff repair: a systematic review and meta-analysis

BACKGROUND

Several factors have been reported to adversely affect clinical and structural outcomes after rotator cuff repair (RCR). However, the effects of smoking on rotator cuff healing and clinical outcomes remain controversial. The purpose of this study was to compare the clinical and structural outcomes after RCR between smokers and nonsmokers. We hypothesized that there would be no significant difference in the clinical scores after RCR and that smoking would be associated with a significantly increased risk of retear and reoperation.

METHODS

This systematic review was performed in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines using the PubMed, Cochrane Library, and Embase databases. We included only articles in which patients underwent arthroscopic and open RCR, the clinical outcome scores were reported for smokers and nonsmokers, and the number of rotator cuff retears and reoperations were reported. Data relevant to this study were extracted and statistically analyzed. We used the Newcastle-Ottawa Scale to assess the risk of bias in each study and calculated the I² value to quantify the effect of heterogeneity.

RESULTS

Fourteen eligible articles were identified, with 73,817 participants (8553 smokers and 65,264 nonsmokers). The meta-analysis demonstrated that there were no significant differences in the American Shoulder and Elbow Surgeons score (P = .10), Simple Shoulder Test score (P = .19), University of California-Los Angeles score (P = .09), or visual analog scale score (P = .19) between smokers and nonsmokers after surgery, but the Constant score was significantly lower (P = .005) for smokers. Smoking was significantly associated with an increased risk of retear (P = .002; risk ratio, 2.06 [95% confidence interval, 1.30-3.28]; I² = 31%) and reoperation (P < .001; risk ratio, 1.29 [95% confidence interval, 1.20-1.40]; I² = 36%) in patients after RCR.

CONCLUSION

Besides the Constant score, which was lower in smokers, there were no significant differences in the clinical scores after RCR between smokers and nonsmokers. However, smoking was associated with a significantly increased risk of retear and reoperation.

Smoking and degenerative spinal disease: A systematic review

Smoking is a major cause of morbidity and mortality worldwide and is responsible for the death of more than 8 million people per year globally. Through a systematic literature review, we aim to review the harmful effects of tobacco smoking on degenerative spinal diseases (DSD). DSD is a debilitating disease and there is a need to identify if smoking can be an attributable contender for the occurrence of this disease, as it can open up avenues for therapeutic options. Sources such as PubMed and Embase were used to review literature, maintaining tobacco smoking and spinal diseases as inclusion factors, excluding any article that did not explore this relationship. Risk of bias was assessed using analysis of results, sample size and methods and limitations. Upon review of the literature, tobacco smoking was found to be a major risk factor for the occurrence of DSDs, particularly lumbar spinal diseases. Smokers also experienced a greater need for surgery and greater postoperative wound healing complications, increased pain perception, delay in recovery and decreased satisfaction after receiving surgery. These effects were noted along the entire spine. Many mechanisms of action have been identified in the literature that provide plausible pictures of how smoking leads to spinal degeneration, exploring possible primary targets which can open up opportunities to develop potential therapeutic agents. More studies on cervical and thoracic spinal degeneration would be beneficial in identifying the effect of nicotine on these spinal levels. Some limitations included insufficient sample size, inconclusive evidence and lack of sufficient repeat studies. However, there appears to be a sufficient amount of research on smoking directly contributing to lumbar spinal pathology.

•

Smoking is a risk factor for the occurence of degenerative spinal disease (DSD).

•

There are numerous pathological mechanisms attributed to spinal pathology by smoking.

•

Smoking appears to be a significant risk factor for lumbar DSDs, with smoke studies also suggesting its role in cervical DSDs.

•

There is insufficient research on the effect of smoking on the thoracic spine.

•

Smoking leads to worse outcomes and potential complications post-surgery, as well as increased pain perception and poorer subjective response post-surgery.

Intervertebral Disc Degeneration Models for Pathophysiology and Regenerative Therapy -Benefits and Limitations

Aim:This review summarized the recent intervertebral disc degeneration (IDD) models and described their advantages and potential disadvantages, aiming to provide an overview for the current condition of IDD model establishment and new ideas for new strategies development of the treatment and prevention of IDD.Methods:The database of PubMed was searched up to May 2021 with the following search terms: nucleus pulposus, annulus fibrosus, cartilage endplate, intervertebral disc(IVD), intervertebral disc degeneration, animal model, organ culture, bioreactor, inflammatory reaction, mechanical stress, pathophysiology, epidemiology. Any IDD model-related articles were collected and summarized.Results:The best IDD model should have the features of repeatability, measurability and controllability. There are a lot of aspects to be considered in the selection of animals. Mice, rats and rabbits are low-cost and easy to access. However, their IVD size and shape are more different from human anatomy than pigs, cattle, sheep and goats. Organ culture models and animal models are two options in model establishment for IDD. The IVD organ culture model can put the studying variables into the controllable system for transitional research. Unlike the animal model, the organ culture model can only be used to evaluate the short-term effects and it is not applicable in simulating the complex process of IDD. Similarly, the animal models induced by different methods also have their advantages and disadvantages. For studying the mechanism of IDD and the corresponding treatment and prevention strategies, the selection of model should be individualized based on the purpose of each study.Conclusions:Various models have different characteristics and scope of application due to their different rationales and methods of construction. Currently, there is no experimental model that can perfectly mimic the degenerative process of human IVD. Personalized selection of appropriate model based on study purpose and experimental designing can enhance the possibility to obtain reliable and real results.

Epidemiology of chronic back pain among adults and elderly from Southern Brazil: a cross-sectional study

BACKGROUND

Chronic back pain (CBP) can negatively affect one's quality of life and health condition, posing significant social and economic burdens.

OBJECTIVES

(1) To determine the prevalence of CBP and analyze associated factors in adult and elderly individuals in a municipality in southern Brazil; (2) to verify who sought medical attention or missed work because of back pain; and (3) to estimate the impact of CBP on selected health outcomes.

METHODS

This was a population-based cross-sectional study conducted with individuals aged 18 years and older. CBP was defined as "pain for three consecutive months in the cervical, thoracic, or lumbar regions in the last year." Demographic, socioeconomic, behavioral, and physical and mental health information was collected. The impact of CBP was assessed by the etiological fraction method.

RESULTS

The prevalence of CBP was 20.7% (95% CI: 18.3, 23.0) among the 1300 study participants. The factors associated with CBP were women, elderly, smokers, obesity, and sleeping fewer hours per night, as well as those with higher mental stress levels, history of fracture, arthritis/rheumatism, and work-related musculoskeletal disorder/repetitive strain injury. One-third of those with CBP missed work (31%) and 68% visited the physician over a 12-month period. All health outcomes analyzed (poor or very poor sleep quality, regular or poor health perception, worsened quality of life, depressive symptoms, perceived sadness) were significantly associated with CBP.

CONCLUSION

One in five adults or elderly reported having CBP over the previous 12 months. This condition was associated with poorer health perception, poorer quality of life, and depressive symptoms.

Canine models of spine disorders

Neck and low back pain are common among the adult human population and impose large social and economic burdens on health care and quality of life. Spine-related disorders are also significant health concerns for canine companions with etiopathogeneses, clinical presentations, and diagnostic and therapeutic options that are very similar to their human counterparts. Historically, induced and spontaneous pathology in laboratory rodents, dogs, sheep, goats, pigs, and nonhuman primates have been used for study of human spine disorders. While each of these can serve as useful preclinical models, they all have inherent limitations. Spontaneously occurring spine disorders in dogs provide highly translatable data that overcome many of the limitations of other models and have the added benefit of contributing to veterinary healthcare as well. For this scoping review, peer-reviewed manuscripts were selected from PubMed and Google Scholar searches using keywords: "intervertebral disc," "intervertebral disc degeneration," "biomarkers," "histopathology," "canine," and "mechanism." Additional keywords such as "injury," "induced model," and "nucleus degeneration" were used to further narrow inclusion. The objectives of this review were to (a) outline similarities in key features of spine disorders between dogs and humans; (b) describe relevant canine models; and (c) highlight the applicability of these models for advancing translational research and clinical application for mechanisms of disease, diagnosis, prognosis, prevention, and treatment, with a focus on intervertebral disc degeneration. Best current evidence suggests that dogs share important anatomical, physiological, histological, and molecular components of spinal disorders in humans, such that induced and spontaneous canine models can be very effective for translational research. Taken together, the peer-reviewed literature supports numerous advantages for use of canine models for study of disorders of the spine when the potential limitations and challenges are addressed.

The Impact of "Vaping" Electronic Cigarettes on Spine Health

“Vaping” or the use of electronic cigarettes (e-cigarettes) has greatly increased within the past decade, with growing popularity among adolescents. E-cigarettes have many harmful effects on multiple organ systems, but more research is needed to fully understand the extent of possible risks. Our narrative literature review aims to provide comprehensive insight into the impact of e-cigarette use on spinal health with a specific focus on intervertebral disc (IVD) health, bone health, and spinal fusion. There are many metallic compounds and chemical flavoring additives within e-cigarette liquids that are associated with human toxicity. These chemical toxins have been linked to increased oxidative stress leading to systemic inflammation. E-cigarette carcinogens have shown to have a toxic effect on osteoblast cells, and long-term use may decrease bone mineral density and increase the future risk for osteoporosis. Additionally, nicotine in e-liquids negatively impacts IVD health by creating hypoxic environments that degenerate the IVD vasculature and cellular matrix. While studies have demonstrated the inhibitory effects of nicotine use on spinal fusions in animal models, the impact of e-cigarette use on spinal fusion operations in human patients is currently lacking. Future research should focus on the influence of e-cigarette use on spinal health, particularly in adolescents with long-term follow-up, as childhood is a critical time for bone growth and development. Additionally, studies exploring the effects of e-cigarettes on spinal surgery outcomes, such as spinal fusions, are sparse in the literature. Further prospective research studies with a focus on the variety of e-cigarette chemical toxins and flavoring agents is needed to assess the impact on spinal health.