Does vitamin D status influence lumbar disc degeneration and low back pain in postmenopausal women? A retrospective single-center study

Potential causal association between serum vitamin D levels and intervertebral disc degeneration: A mendelian randomization study

OBJECTIVES

Intervertebral disc degeneration (IDD) is a prevalent musculoskeletal disorder with substantial implications for disability and healthcare expenditures. The role of serum vitamin D (25-Hydroxyvitamin D, 25(OH)D) levels in the pathogenesis of various musculoskeletal conditions has been explored in prior observational studies, suggesting a potential association. While previous observational studies have suggested an association between the two conditions, it might confound the effect of 25(OH)D on IDD. This Mendelian randomization (MR) study seeks to elucidate the causal relationship between 25(OH)D and IDD.

METHODS

We performed a MR analysis using summary-level data from genome-wide association studies (GWAS) of 25(OH)D (sample size = 441,291 European) and IDD (sample size = 336,439 (cases = 41,669, controls = 294,770) European). Single nucleotide polymorphisms (SNPs) significantly associated with 25(OH)D (p < 5 × 10-8) were selected as instrumental variables. The associations between genetically predicted 25(OH)D and IDD were estimated using the inverse-variance weighted (IVW) method, with sensitivity analyses employing the weighted median, MR-Egger, and MR-PRESSO approaches to assess the robustness of the findings.

RESULTS

In the primary IVW analysis, genetically predicted 25(OH)D was unrelated associated with IDD (odds ratio (OR) = 0.9671, 95% confidence interval (CI): 0.8956-1.0444, p = 0.39). The results remained consistent across the sensitivity analyses, and no significant directional pleiotropy was detected (MR-Egger intercept: p = 0.64).

CONCLUSIONS

This study found no obvious evidence that 25(OH)D is causally associated with IDD risks. We call for larger sample size studies to further unravel the potential causal relationship and the exact mechanism.

Vitamin D delays intervertebral disc degeneration and improves bone quality in ovariectomized rats

Known to be involved in bone-cartilage metabolism, Vitamin D (VD) may play a role in human's disc pathophysiology. Given that postmenopausal women are prone to suffer VD deficiency and intervertebral disc degeneration (IDD), this study is intended to investigate whether VD can delay IDD in ovariectomized rats by improving bone microstructure and antioxidant stress. Female Sprague-Dawley rats were randomly allocated into four groups: sham, oophorectomy (OVX)+VD deficiency (VDD), OVX, and OVX+VD supplementation (VDS). In vivo, after a 6-month intervention, imaging and pathology slice examinations showed that IDD induced by OVX was significantly alleviated in VDS and deteriorated by VDD. The expressions of aggrecan and Collagen II in intervertebral disc were reduced by OVX and VDD, and elevated by VDS. Compared with the OVX+VDD and OVX group vertebrae, OVX+VDS group vertebrae showed significantly improved endplate porosity and lumbar bone mineral density with increased percent bone volume and trabecular thickness. Furthermore, 1α,25(OH)2D3 restored the redox balance (total antioxidant capacity, ratio of oxidized glutathione/glutathione) in the disc. The cocultivation of 1α,25(OH)2D3 and nucleus pulposus cells (NPCs) was conducted to observe its potential ability to resist excessive oxidative stress damage induced by H2O2. In vitro experiments revealed that 1α,25(OH)2D3 reduced the senescence, apoptosis, and extracellular matrix degradation induced by H2O2 in NPCs. In conclusion, VDS exhibits protective effects in OVX-induced IDD, partly by regulating the redox balance and preserving the microstructure of endplate. This finding provides a new idea for the prevention and treatment of IDD.

Causal associations between modifiable risk factors and intervertebral disc degeneration

BACKGROUND

Intervertebral disc degeneration (IVDD) is a common degenerative condition, which is thought to be a major cause of lower back pain (LBP). However, the etiology and pathophysiology of IVDD are not yet completely clear.

PURPOSE

To examine potential causal effects of modifiable risk factors on IVDD.

STUDY DESIGN

Bidirectional Mendelian randomization (MR) study.

PATIENT SAMPLE

Genome-wide association studies (GWAS) with sample sizes between 54,358 and 766,345 participants.

OUTCOME MEASURES

Outcomes included (1) modifiable risk factors associated with IVDD use in the forward MR; and (2) modifiable risk factors that were determined to have a causal association with IVDD in the reverse MR, including smoking, alcohol intake, standing height, education level, household income, sleeplessness, hypertension, hip osteoarthritis, HDL, triglycerides, apolipoprotein A-I, type 2 diabetes, fasting glucose, HbA1c, BMI and obesity trait.

METHODS

We obtained genetic variants associated with 33 exposure factors from genome-wide association studies. Summary statistics for IVDD were obtained from the FinnGen consortium. The risk factors of IVDD were analyzed by inverse variance weighting method, MR-Egger method, weighted median method, MR-PRESSO method and multivariate MR Method. Reverse Mendelian randomization analysis was performed on risk factors found to be caustically associated with IVDD in the forward Mendelian randomization analysis. The heterogeneity of instrumental variables was quantified using Cochran's Q statistic.

RESULTS

Genetic predisposition to smoking (OR=1.221, 95% CI: 1.068-1.396), alcohol intake (OR=1.208, 95% CI: 1.056-1.328) and standing height (OR=1.149, 95% CI: 1.072-1.231) were associated with increased risk of IVDD. In addition, education level (OR=0.573, 95%CI: 0.502-0.654)and household income (OR=0.614, 95%CI: 0.445-0.847) had a protective effect on IVDD. Sleeplessness (OR=1.799, 95%CI: 1.162-2.783), hypertension (OR=2.113, 95%CI: 1.132-3.944) and type 2 diabetes (OR=1.069, 95%CI: 1.024-1.115) are three important risk factors causally associated with the IVDD. In addition, we demonstrated that increased levels of triglycerides (OR=1.080, 95%CI:1.013-1.151), fasting glucose (OR=1.189, 95%CI:1.007-1.405), and HbA1c (OR=1.308, 95%CI:1.017-1.683) could significantly increase the odds of IVDD. Hip osteoarthritis, HDL, apolipoprotein A-I, BMI and obesity trait factors showed bidirectional causal associations with IVDD, therefore we considered the causal associations between these risk factors and IVDD to be uncertain.

CONCLUSIONS

This MR study provides evidence of complex causal associations between modifiable risk factors and IVDD. It is noteworthy that metabolic disturbances appear to have a more significant effect on IVDD than biomechanical alterations, as individuals with type 2 diabetes, elevated triglycerides, fasting glucose, and elevated HbA1c are at higher risk for IVDD, and the causal association of obesity-related characteristics with IVDD incidence is unclear. These findings provide new insights into potential therapeutic and prevention strategies. Further research is needed to clarify the mechanisms of these risk factors on IVDD.

Sirt1 protects against intervertebral disc degeneration induced by 1,25-dihydroxyvitamin D insufficiency in mice by inhibiting the NF-κB inflammatory pathway

Background

It has been demonstrated that vitamin D deficiency is associated with an increased risk of patients developing lumbar disc herniation. However, intervertebral disc degeneration caused by active vitamin D deficiency has not been reported. Thus, the purpose of this study was to e investigate the role and mechanism of 1,25-dihydroxyvitamin D (1,25(OH)₂D) insufficiency in promoting intervertebral disc degeneration.

Methods

The phenotypes of intervertebral discs were compared in wild-type mice and mice with heterozygous deletion of 1α-hydroxylase [1α(OH)ase^+/-] at 8 mouths of age using iconography, histology and molecular biology. A mouse model that overexpressed Sirt1 in mesenchymal stem cells on a 1α(OH)ase^+/- background (Sirt1^Tg/1α(OH)ase^+/-) was generated by crossing Prx1-Sirt1 transgenic mice with 1α(OH)ase^+/- mice and comparing their intervertebral disc phenotypes with those of Sirt1^Tg, 1α(OH)ase^+/- and wild-type littermates at 8 months of age. A vitamin D receptor (VDR)-deficient cellular model was generated by knock-down of endogenous VDR using Ad-siVDR transfection into nucleus pulposus cells; VDR-deficient nucleus pulposus cells were then treated with or without resveratrol. The interactions between Sirt1 and acetylated p65, and p65 nuclear localization, were examined using co-immunoprecipitation, Western blots and immunofluorescence staining. VDR-deficient nucleus pulposus cells were also treated with 1,25(OH)₂D₃, or resveratrol or 1,25(OH)₂D₃ plus Ex527 (an inhibitor of Sirt1). Effects on Sirt1 expression, cell proliferation, cell senescence, extracellular matrix protein synthesis and degradation, nuclear factor-κB (NF-κB), and expression of inflammatory molecules, were examined, using immunofluorescence staining, Western blots and real-time RT-PCR.

Results

1,25(OH)₂D insufficiency accelerated intervertebral disc degeneration by reducing extracellular matrix protein synthesis and enhancing extracellular matrix protein degradation with reduced Sirt1 expression in nucleus pulposus tissues. Overexpression of Sirt1 in MSCs protected against 1,25(OH)₂D deficiency-induced intervertebral disc degeneration by decreasing acetylation and phosphorylation of p65 and inhibiting the NF-κB inflammatory pathway. VDR or resveratrol activated Sirt1 to deacetylate p65 and inhibit its nuclear translocation into nucleus pulposus cells. Knockdown of VDR decreased VDR expression and significantly reduced the proliferation and extracellular matrix protein synthesis of nucleus pulposus cells, significantly increased the senescence of nucleus pulposus cells and significantly downregulated Sirt1 expression, and upregulated matrix metallopeptidase 13 (MMP13), tumor necrosis factor-α (TNF-α) and interleukin 1β (IL-1β) expression; the ratios of acetylated and phosphorylated p65/p65 in nucleus pulposus cells were also increased. Treatment of nucleus pulposus cells with VDR reduction using 1,25(OH)₂D₃ or resveratrol partially rescued the degeneration phenotypes, by up-regulating Sirt1 expression and inhibiting NF-κB inflammatory pathway; these effects in nucleus pulposus cells were blocked by inhibition of Sirt1.

Conclusion

Results from this study indicate that the 1,25(OH)₂D/VDR pathway can prevent the degeneration of nucleus pulposus cells by inhibiting the NF-κB inflammatory pathway mediated by Sirt1.The Translational Potential of This Article: This study provides new insights into the use of 1,25(OH)₂D₃ to prevent and treat intervertebral disc degeneration caused by vitamin D deficiency.

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.

Vertebral endplate defects are associated with bone mineral density in lumbar degenerative disc disease

PURPOSE

Evidence has shown that lumbar vertebral endplate defects are clinically relevant and closely related to disc degeneration, but the relationship between endplate defects and bone mineral density (BMD) remains unclear. This study aimed to explore the association between endplate defects and BMD-related values in patients with lumbar degenerative disc disease (LDD).

METHODS

Three hundred and twenty-five Chinese adult subjects diagnosed with LDD underwent dual energy X-ray absorptiometry. Endplate defects were classified using lumbar MRI. Groups were subdivided based on the occurrence rates of defect endplates. BMD at the lumbar vertebral and bilateral femur necks was compared between groups, and the association between endplate defects and lumbar BMD-related values was analyzed and adjusted for confounders including age, sex, serum levels of 25-hydroxy vitamin D (25(OH)D), calcium (Ca) and phosphorus (P).

RESULTS

Of 325 patients and 3250 endplates, 59.72% had defects, and 188 patients were divided into the higher defect rate group (occurrence rate > 50%). The higher defect rate group was associated with older age, more common postmenopausal females, higher osteoporosis rates and lower serum Ca and P levels. Lumbar BMD was greater than that at bilateral femur necks and was not equal to osteoporosis diagnosis. Endplate defects were more prevalent in lower segments. The occurrence of endplate defects was positively associated with lumbar BMD-related values in the partial correlation analysis. The association between endplate defects and lumbar BMD varies for subtypes and segments, with a trend of positive association in rim and erosive subtypes after adjusting for confounders.

CONCLUSIONS

The present study demonstrated that the occurrence of endplate defects was associated with greater lumbar BMD values in patients with LDD. This association varies for different defect subtypes and segments. The results indicated that endplate defects should be taken into consideration in osteoporosis treatment to alleviate disc degeneration.

VDR promotes nucleus pulposus cell mitophagy as a protective mechanism against oxidative stress injury

Intervertebral disk degeneration (IDD) is a common aging disease. Excessive apoptosis of nucleus pulposus (NP) cells has been widely considered a main contributor to IDD. Emerging science has shown that autophagy plays a protective role against apoptosis under oxidative stress. Vitamin D receptor (VDR) is a steroid hormone receptor that can regulate autophagy. The purpose of this study was to clarify whether VDR alleviates IDD by promoting autophagy. H₂O₂ stimulation was used to establish oxidative stress conditions. Initially, the expression level of VDR in human degenerative NP tissues was measured by immunohistochemistry. In addition, the CRISPR-dCas9-VPR system and siRNA were utilized to upregulate or downregulate VDR and Parkin expression, respectively. Autophagic and apoptotic markers were determined by Western blotting and RT-qPCR. Transmission electron microscopy was used to monitor the occurrence of autophagy in rat NP cells. VDR expression was downregulated in human degenerative NP tissues and H₂O₂-stimulated rat NP cells, indicating a negative correlation between VDR expression and IDD. VDR overexpression promoted mitophagy and prevented apoptosis and mitochondrial injury under oxidative stress. Additionally, mitophagy inhibition by 3-MA abolished the protective effect of VDR activation in vitro. Furthermore, VDR activation promoted mitophagy via the PINK1/Parkin pathway in H₂O₂-treated NP cells. This study demonstrates that VDR activation ameliorates oxidative damage and decreases NP cell apoptosis by promoting PINK1/Parkin-dependent mitophagy, indicating that VDR may serve as a promising therapeutic target in the management of IDD.

Recent Advances in Managing Spinal Intervertebral Discs Degeneration

Low back pain (LBP) represents a frequent and debilitating condition affecting a large part of the global population and posing a worldwide health and economic burden. The major cause of LBP is intervertebral disc degeneration (IDD), a complex disease that can further aggravate and give rise to severe spine problems. As most of the current treatments for IDD either only alleviate the associated symptoms or expose patients to the risk of intraoperative and postoperative complications, there is a pressing need to develop better therapeutic strategies. In this respect, the present paper first describes the pathogenesis and etiology of IDD to set the framework for what has to be combated to restore the normal state of intervertebral discs (IVDs), then further elaborates on the recent advances in managing IDD. Specifically, there are reviewed bioactive compounds and growth factors that have shown promising potential against underlying factors of IDD, cell-based therapies for IVD regeneration, biomimetic artificial IVDs, and several other emerging IDD therapeutic options (e.g., exosomes, RNA approaches, and artificial intelligence).

Vitamin D/VDR in the pathogenesis of intervertebral disc degeneration: Does autophagy play a role?

To date, the underlying mechanisms involved intervertebral disc degeneration (IDD) remain unclear, which has hindered the development of molecular biological therapy for IDD. Autophagy is vital for intracellular quality control and metabolic balance in intervertebral disc cells. Hence, autophagy homeostasis is important. Emerging evidence has implicated vitamin D (VD) and the vitamin D receptor (VDR) in IDD progression because of their effects on different autophagy steps. However, the results of clinical trials in which VD supplementation was assessed as a treatment for IDD are controversial. Furthermore, experimental studies on the interplay between VD/VDR and autophagy are still in their infancy. In view of the significance of the crosstalk between VD/VDR and autophagy components, this review focuses on the latest research on VD/VDR modulation in autophagy and investigates the possible regulatory mechanisms. This article will deepen our understanding of the relationship between VD/VDR and autophagy and suggests novel strategies for IDD prevention and treatment.

Frequency of vitamin d deficiency in patients with lumbar spinal stenosis and its relationship with obesity, depression, and pain intensity: a cross-sectional study

ABSTRACT Objective This study was conducted to determine the frequency of vitamin D deficiency in patients with lumbar spinal stenosis and to define the relationship between vitamin D levels and obesity, depression, and pain intensity. Methods This study was conducted with 69 patients (Male = 32, Female = 37) diagnosed with lumbar spinal stenosis. The participants’ 25(OH)D levels were measured by radioimmunoassay. In addition, bone metabolic status, including bone mineral density and bone turnover markers, was also evaluated. The Beck Depression Inventory was used to determine the depression statuses of the patients, while the McGill Melzack Pain Questionnaire was administered to measure pain intensity. The results were evaluated at a significance level of p<0.05. Results Vitamin D deficiency (<20 ng/mL) was found in 76.8% of the patients. Binary logistic regression analysis showed a significantly higher frequency of vitamin D deficiency in patients who: 1) had higher body mass indexes (OR 3.197, 95% CI 1.549-6.599); 2) fared higher in Beck’s depression score (OR 1.817, 95% CI 1.027–3.217); and 3) were female rather than male (OR 1.700, 95% CI 0.931-3.224) (p<0.05). Conclusion In this study, vitamin D deficiency was prevalent in lumbar spinal stenosis patients. In addition, obese, depressed, and female individuals have higher risks of vitamin D deficiency.

Smoking behavior and circulating vitamin D levels in adults: A meta-analysis

To determine the effect of smoking on circulating vitamin D in adults, we performed a meta-analysis. Literature before 9 May 2021 was retrieved from electronic literature databases such as EMBASE, PubMed, and Cochrane. The quality of the included studies was assessed by two researchers against the Newcastle-Ottawa scale and JBI Evidence-based Health Care Centre criteria. All eligible studies and statistical analyses were performed using STATA 14. Twenty-four studies with 11,340 participants meeting the criteria were included in the meta-analysis. The results of meta-analysis showed that the level of circulating 25(OH)D in smokers was lower than that in nonsmokers. A subgroup analysis based on vitamin D supplement use showed that both smokers who used vitamin D supplements and smokers who did not use vitamin D supplements had lower blood 25(OH)D levels compared with the control group. In addition, subjects were divided into different subgroups according to age for meta-analysis, and the results showed that the serum 25(OH)D level in each subgroup of smokers was lower than that in the control group. This meta-analysis revealed differences in circulating vitamin D levels between smokers and nonsmokers, with smokers likely to have lower circulating vitamin D levels.

Correlation between Vitamin D deficiency and nonspecific chronic low back pain: A retrospective observational study

CONTEXT

Chronic lower back pain (CLBP) and Vitamin D deficiency are two common conditions presenting to primary care physicians.

AIMS

To study the vitamin D status in North Indians presenting with nonspecific CLBP and the correlation between vitamin D levels and pain severity by the Visual Analogue Scale (VAS).

SETTINGS AND DESIGN

An observational study. Record of all CLBP patients presenting to the outpatient department in 2019, were analyzed, retrospectively.

METHODS AND MATERIALS

All the patients of age 18 to 65 and either sex with nonspecific CLBP were included. Patients were divided into two: Vitamin D deficient (Group 1) and normal (Group 2) with cut off Serum Vitamin D values at 30 ng/mL. Demographic data and Visual Analogue Scale scores (VAS) of both groups were recorded.

STATISTICAL ANALYSIS USED

Correlations between Vitamin D values and VAS scores were investigated using the Spearman coefficient, and the results with P of ≤ 0.05 were contemplated significant.

RESULTS

Of total 376 patients with nonspecific CLBP, the majority were adults, females, married, vegetarians, overweight or obese, and had a mean sun exposure time of two hours. Vitamin D deficient Group 1 had 302 (80.32%) patients with significantly lower (P < 0.0001) mean vitamin D levels compared to Group 2 (74 patients i.e., 19.68%). Spearman's rho coefficient between vitamin D and VAS, showed a negative correlation (-0.554), with a P value < 0.00001.

CONCLUSIONS

This study indicated a high probability of vitamin D deficiency in the nonspecific CLBP population and a negative correlation between vitamin D status and pain severity.

Identification of risk factors for falls in postmenopausal women: a systematic review and meta-analysis

The purpose of this study was to identify risk factors for falls in postmenopausal women and provide evidence for the primary prevention of falls in postmenopausal women. The protocol for this meta-analysis is registered with PROSPERO (CRD42020170927). We searched PubMed, the Cochrane Library and EMBASE for observational studies on the risk factors for falls in postmenopausal women. Review Manager 5.3 was used to calculate the relative risk (RR) or weighted mean difference (WMD) of potential risk factors related to falls. STATA 14.0 was used for the quantitative evaluation of publication bias. Eleven studies with 42,429 patients from 7 countries were included. The main risk factors for falls in postmenopausal women were patient sociodemographic risk factors (age: WMD = 0.37, 95% CI 0.07 to 0.68; body weight: WMD = 0.88, 95% CI 0.56 to 1.12; BMI: WMD = 0.34, 95% CI 0.21 to 0.46; exercise: RR = 0.97, 95% CI 0.94 to 0.99; and FES-I: WMD = 6.60, 95% CI 0.72 to 12.47) and medical risk factors (dietary calcium intake: WMD = - 16.91, 95% CI - 25.80 to - 8.01; previous fracture history: RR = 1.21, 95% CI 1.13 to 1.29; previous falls: RR = 2.02, 95% CI 1.91 to 2.14; number of diseases, ˃ 2: RR = 1.17, 95% CI 1.11 to 1.23; and number of reported chronic health disorders: WMD = 0.30, 95% CI 0.10 to 0.49). Knowledge of the many risk factors associated with falls in postmenopausal women can aid in fall prevention. However, we cannot rule out some additional potential risk factors (age at the onset of menopause, years since last menstruation, hormone therapy and BMD) that need further clinical research.

Vitamin D supplementation after the menopause

The purpose of this review was to assess recent evidence regarding the effects of low vitamin D levels on some highly prevalent clinical conditions of postmenopausal women. We reviewed and selected recent literature regarding menopause-related conditions associated with vitamin D deficiency and interventions to manage them. Low circulating 25-hydroxyvitamin D (25(OH)D) levels related to menopause are linked to diet, lifestyle, changes in body composition, insulin sensitivity, and reduced physical activity. Vitamin D supplementation increases serum 25(OH)D levels while normalizing parathyroid hormone and bone markers, and in women with serum 25(OH)D levels below 10 ng/ml supplementation may improve bone mineral density. Low vitamin D status has been associated with the metabolic syndrome, high triglyceride levels, and low high-density lipoprotein cholesterol levels. When compared with placebo, vitamin D supplementation may lower the risk of the metabolic syndrome, hypertriglyceridemia, and hyperglycemia. There is an inverse relationship between fat mass and serum 25(OH)D levels and, therefore, the dosage of supplementation should be adjusted according to the body mass index. Although vitamin D supplementation may improve glucose metabolism in prediabetic subjects, data regarding muscle strength are conflictive. There is evidence that vitamin D over-treatment, to reach extremely high circulating 25(OH)D levels, does not result in better clinical outcomes. The identification and treatment of vitamin D deficiency in postmenopausal women may improve their general health and health outcomes. Vitamin D supplementation should preferably be based on the use of either cholecalciferol or calcifediol.