Effects of Sex and Obesity on LEP Variant and Leptin Level Associations in Intervertebral Disc Degeneration

Targeting FABP4 to Inhibit AGEs-RAGE/NF-κB Signalling Effectively Ameliorates Nucleus Pulposus Dysfunction and Angiogenesis in Obesity-Related Intervertebral Disc Degeneration

Intervertebral disc degeneration (IVDD) is a primary contributor to low back pain, posing significant social and economic burdens. Increasing evidence shows that obesity contributes to IVDD, yet the underlying mechanisms remain elusive. Here, we firstly revealed a causal correlation between obesity and IVDD via a two-sample mendelian randomization analysis and identified fatty acid-binding protein 4 (FABP4) as the potential regulator to associate IVDD and obesity. Elevated FABP4 expression promoted extracellular matrix (ECM) disequilibrium and angiogenesis to exacerbate IVDD progression. Genetically knocking out or pharmacologically inhibiting FABP4 in high-fat diet-induced mice alleviated IVDD. Mechanistically, obesity activated the mammalian target of rapamycin complex 1 (mTORC1), which upregulated FABP4 expression, leading to the accumulation of advanced glycation end-products (AGEs) in intervertebral disc tissue. AGEs further activated the NF-κB signalling pathway, exacerbating ECM degradation and neovascularization. Conversely, rapamycin-mediated inhibition of mTORC1 suppressed FABP4 expression in nucleus pulposus cells (NPCs), alleviating IVDD in vivo. Collectively, our findings reveal a critical role of the obesity-induced mTORC1-FABP4 axis in ECM degradation and angiogenesis during IVDD progression. Targeting FABP4 may represent a promising therapeutic strategy for IVDD in obese individuals.

Lipid metabolic disorders and their impact on cartilage endplate and nucleus pulposus function in intervertebral disk degeneration

Lipid metabolism encompasses the processes of digestion, absorption, synthesis, and degradation of fats within biological systems, playing a crucial role in sustaining normal physiological functions. Disorders of lipid metabolism, characterized by abnormal blood lipid levels and dysregulated fatty acid metabolism, have emerged as significant contributors to intervertebral disk degeneration (IDD). The pathogenesis of IDD is multifaceted, encompassing genetic predispositions, nutritional and metabolic factors, mechanical stressors, trauma, and inflammatory responses, which collectively facilitate the progression of IDD. Although the precise mechanisms underlying IDD remain incompletely elucidated, there is substantial consensus regarding the close association between lipid metabolism disorders and its development. Intervertebral disks are essential for maintaining spinal alignment. Their primary functions encompass shock absorption, preservation of physiological curvature, facilitation of movement, and provision of stability. The elasticity and thickness of these disks effectively absorb daily impacts, safeguard the spine, uphold its natural curvature and flexibility, while also creating space for nerve roots to prevent compression and ensure normal transmission of nerve signals. Research indicates that such metabolic disturbances may compromise the functionality of cartilaginous endplates (CEP) and nucleus pulposus (NP), thereby facilitating IDD's onset and progression. The CEP is integral to internal material exchange and shock absorption while mitigating NP herniation under mechanical load conditions. As the central component of intervertebral disks, NP is essential for maintaining disk height and providing shock-absorbing capabilities; thus, damage to these critical structures accelerates IDD progression. Furthermore, lipid metabolism disorders contribute to IDD through mechanisms including activation of endoplasmic reticulum stress pathways, enhancement of oxidative stress levels, induction of cellular pyroptosis alongside inhibition of autophagy processes-coupled with the promotion of inflammation-induced fibrosis and fibroblast proliferation leading to calcification within intervertebral disks. This review delineates the intricate interplay between lipid metabolism disorders and IDD; it is anticipated that advancing our understanding of this pathogenesis will pave the way for more effective preventive measures and therapeutic strategies against IDD in future research.

Does body mass index influence intraoperative costs and operative times for open transforaminal lumbar interbody fusion? A time-driven activity-based costing analysis

Background

The increasing prevalence of obesity has raised concerns about its impact on surgical outcomes and healthcare costs. This study evaluates the influence of Body Mass Index (BMI) on intraoperative costs and operative times during open Transforaminal Lumbar Interbody Fusion (TLIF) procedures using a Time-Driven Activity-Based Costing (TDABC) approach.

Methods

A retrospective analysis was conducted on 279 patients who underwent TLIF between 2019 and 2022. Patients were categorized into 5 BMI cohorts: healthy weight (BMI 18.5-24.99), overweight (BMI 25.0-29.99), Class I obese (BMI 30.0-34.99), Class II obese (BMI 35.0-39.99), and Class III obese (BMI >40). Intraoperative costs were calculated using TDABC methodology, with costs segmented into supply and personnel expenses. Operative times were measured in 3 phases: surgery time (incision to closure), OR time (patient entering to leaving), and turnover time. Multivariable regression models assessed the relationship between BMI and various intraoperative time and cost metrics, adjusting for potential confounders.

Results

BMI was significantly associated with increased operative times and personnel costs. Each unit increase in BMI corresponded to an additional 1.90 minutes in the operating room (p = .01) and a $25.72 increase in personnel costs (p = .008). However, no significant association was found between BMI and total or supply costs. Regression analyses indicated that obese patients did not significantly differ from healthy weight patients in terms of total intraoperative costs.

Conclusions

Higher BMI is associated with increased operative times and personnel costs in TLIF procedures, though it does not significantly impact total intraoperative costs when controlling for confounders. These findings suggest that BMI may not need to be a significant deterrent in patient selection for TLIF under bundled payment models.

Assessing the causal relationship between CRP, IL-1α, IL-1β, and IL-6 levels and intervertebral disc degeneration: a two-sample Mendelian randomization study

Growing research has suggested an association between chronic inflammation and Intervertebral disc degeneration (IVDD), but whether there is a causal effect remains unknown. This study adopted two-sample Mendelian randomization (MR) approach to explore the etiological role of chronic inflammation in IVDD risk. Here, summary statistics for C-reactive protein (CRP), interleukin (IL)-1 α , IL-1 β , IL-6 expression and IVDD were obtained from genome-wide association studies (GWAS) of European ancestry. MR analyses were conducted by using inverse variance weighted (IVW), Wald Ratio, weighted median, and MR-Egger method. Sensitivity analyses were conducted to assess the robustness of the results. The MR analyses suggested a lack of causal association of CRP, IL-6 , and IL-1 α levels on IVDD (CRP-IVDD: odds ratio [OR] = 0.97, 95% confidence interval [CI] 0.86-1.09, P = 0.583; IL-6-IVDD: OR = 1.04, 95% CI 0.86-1.27, P = 0.679; IL-1 α -IVDD: OR = 1.09, 95%CI 1.00-1.18, P = 0.058). However, there was a sign of a connection between genetically elevated IL-1 β levels and a decreased IVDD incidence (OR = 0.87, 95%CI 0.77-0.99, P = 0.03). Our findings suggest a connection between IL-1 β levels and the risk of IVDD. However, due to the support of only one SNP, heterogeneity and pleiotropy tests cannot be performed, the specific underlying mechanisms warrant further investigation.

Serum iron concentration and leptin inversely relate, partially mediated by body mass index in American adults

Iron metabolism and leptin are interconnected, and both link with obesity. In this cross-sectional study, we hypothesized that serum iron markers associate with leptin, with body mass index (BMI) acting as a mediator, confounder, and effect modifier in this relationship. We analyzed data from the National Health and Nutrition Examination Survey III, with a focus on serum iron markers and leptin. The relationship between serum iron markers and leptin was determined by multiple linear regression. The bootstrap method was used to investigate the mediating effect of BMI on this association. Among 3888 American adults, serum iron and transferrin saturation showed a negative association with leptin (log2-transformed) (β: -0.010, 95% confidence interval [CI], -0.013 to -0.006, P < .001; β: -0.006, 95% CI, -0.008 to -0.004, P < .001). Total iron-binding capacity was positively associated with the serum concentration of leptin (log2-transformed) (β: 0.002, 95% CI, 0-0.004, P = .0292). Sex, BMI, and body fat percentage significantly influenced these associations. Notably, the association between the iron markers and leptin diminished in individuals with a BMI ≥30 kg/m2. There was no observable relationship between leptin and serum ferritin concentrations. BMI mediated 4.81% of the serum iron-leptin association, with no mediation of body fat percentage. Our study identified a link between serum iron and leptin, with BMI as a mediating factor. In clinical settings, it is vital to understand how treatments targeting iron metabolism can directly impact serum leptin concentration and the subsequent physiological changes.

Roles of organokines in intervertebral disc homeostasis and degeneration

The intervertebral disc is not isolated from other tissues. Recently, abundant research has linked intervertebral disc homeostasis and degeneration to various systemic diseases, including obesity, metabolic syndrome, and diabetes. Organokines are a group of diverse factors named for the tissue of origin, including adipokines, osteokines, myokines, cardiokines, gastrointestinal hormones, and hepatokines. Through endocrine, paracrine, and autocrine mechanisms, organokines modulate energy homeostasis, oxidative stress, and metabolic balance in various tissues to mediate cross-organ communication. These molecules are involved in the regulation of cellular behavior, inflammation, and matrix metabolism under physiological and pathological conditions. In this review, we aimed to summarize the impact of organokines on disc homeostasis and degeneration and the underlying signaling mechanism. We focused on the regulatory mechanisms of organokines to provide a basis for the development of early diagnostic and therapeutic strategies for disc degeneration.

Association of polymorphism in leptin receptor gene with susceptibility of adolescent idiopathic scoliosis

PURPOSE

Abnormal leptin bioavailability has play key roles in the etiology of adolescent idiopathic scoliosis (AIS). Both leptin and its receptor levels may be modulated by the presence of genetic polymorphisms. This study aimed to evaluate the role of polymorphisms in the leptin (LEP) and its main receptor (LEPR) genes in the AIS susceptibility in girls.

METHODS

A retrospective case-control study was conducted with 189 AIS and 240 controls. LEP rs2167270 and LEPR rs2767485 polymorphisms were genotyped using a TaqMan validated assay. Associations were evaluated by odds ratios (OR) and 95% confidence intervals (CI).

RESULTS

The AIS group showed a predominance of girls under 18 years old (n = 140, 74.1%), 148 (78.3%) had low or normal BMI, 111 (58.7%) had Cobb ≥ 45º and 130 (68.7%) were skeletally mature. Minor allele frequencies of rs2167270 and rs2767485 were 35.7% and 18.3%, for AIS and 35.6% and 25.4% for controls, respectively. LEPR rs2767485 T and TC + TT were associated with higher risk of AIS (OR = 1.53; 95% CI = 1.09-2.13 and OR = 1.84; 95% CI = 1.69-2.01, respectively), since CC genotype was only present in the control group. In addition, the LEP rs2167270 GA + AA was more frequent in low weight group (BMI ≤ 24.9) of girls with AIS. There was no significant association between LEP rs2167270 and AIS susceptibility, and LEPR rs2767485 and BMI.

CONCLUSION

The LEPR rs2767485 was associated with the genetic susceptibility of AIS and LEP rs2167270 with low BMI. These data can contribute to the identification of genetic biomarkers to improve the diagnosis and treatment.

Predictive Factors Associated with Chronic Neck Pain in Patients with Cervical Degenerative Disease: A Retrospective Cohort Study

Purpose

To explore the predictive factors of neck pain (NP) in patients with cervical degenerative disease by retrospectively analyzing their occupational and demographic characteristics and to provide a valuable reference for preventing and treating chronic NP.

Patients and Methods

We retrospectively reviewed the occupational and demographic data of patients with cervical degenerative disease who had undergone anterior cervical surgery between June 2021 and December 2022 at our center. The patients were divided into NP and no-NP groups based on whether they had chronic NP before surgery. Relevant occupational and demographic data from all patients were statistically analyzed, and all variables were made categorical. Forward stepwise logistic regression models were constructed for preoperative chronic neck pain to explore the possible risk factors associated with chronic neck pain.

Results

The differences in smoking, being an office worker, BMI, and disease types between NP and no-NP groups were statistically significant. In contrast, there were no statistically significant in age, sex, academic level, duration, and degeneration grade between the two groups. Moreover, further logistic regression analysis indicated that smoking, being an office worker, having an abnormal BMI, and cervical spondylotic radiculopathy (CSR) were related to chronic neck pain.

Conclusion

The present study indicated that smoking, being an office worker, having an abnormal BMI, and CSR were predisposing risk factors for NP associated with cervical degenerative disease. Although intervertebral disc degeneration is the pathology basis of NP, the degeneration grade was not related to the occurrence of NP in our current study. Therefore, quitting smoking, avoiding sedentariness, and maintaining a normal BMI may prevent NP to some extent.

Comparative histopathological analysis of age-associated intervertebral disc degeneration in CD-1 and C57BL/6 mice: Anatomical and sex-based differences

Background

Intervertebral disc (IVD) degeneration is a major contributor to back pain and disability. The cause of IVD degeneration is multifactorial, with no disease-modifying treatments. Mouse models are commonly used to study IVD degeneration; however, the effects of anatomical location, strain, and sex on the progression of age-associated degeneration are poorly understood.

Methods

A longitudinal study was conducted to characterize age-, anatomical-, and sex-specific differences in IVD degeneration in two commonly used strains of mice, C57BL/6 and CD-1. Histopathological evaluation of the cervical, thoracic, lumbar, and caudal regions of mice at 6, 12, 20, and 24 months of age was conducted by two blinded observers at each IVD for the nucleus pulposus (NP), annulus fibrosus (AF), and the NP/AF boundary compartments, enabling analysis of scores by tissue compartment, summed scores for each IVD, or averaged scores for each anatomical region.

Results

C57BL/6 mice displayed mild IVD degeneration until 24 months of age; at this point, the lumbar spine demonstrated the most degeneration compared to other regions. Degeneration was detected earlier in the CD-1 mice (20 months of age) in both the thoracic and lumbar spine. In CD-1 mice, moderate to severe degeneration was noted in the cervical spine at all time points assessed. In both strains, age-associated IVD degeneration in the thoracic and lumbar spine was associated with increased histopathological scores in all IVD compartments. In both strains, minimal degeneration was detected in caudal IVDs out to 24 months of age. Both C57BL/6 and CD-1 mice displayed sex-specific differences in the presentation and progression of age-associated IVD degeneration.

Conclusions

These results showed that the progression and severity of age-associated degeneration in mouse models is associated with marked differences based on anatomical region, sex, and strain. This information provides a fundamental baseline characterization for users of mouse models to enable effective and appropriate experimental design, interpretation, and comparison between studies.

Leptin and the rs2167270 Polymorphism Are Associated with Glycemic Control in Type Two Diabetes Mellitus Patients on Metformin Therapy

Background and Objectives: Type two diabetes mellitus (T2DM) is a chronic disease with debilitating complications and high mortality. Evidence indicates that good glycemic control delays disease progression and is hence a target of disease management protocols. Nonetheless, some patients cannot maintain glycemic control. This study aimed to investigate the association between serum leptin levels and several SNPs of the LEP gene with the lack of glycemic control in T2DM patients on metformin therapy. Materials and Methods: In a hospital-based case-control study, 170 patients with poor glycemic control and 170 patients with good glycemic control were recruited. Serum leptin was measured. Patients were genotyped for three SNPs in the LEP gene (rs7799039, rs2167270, and rs791620). Results: Serum leptin was significantly lower in T2DM patients with poor glycemic control (p < 0.05). In multivariate analysis, serum leptin levels significantly lowered the risk of having poor glycemic control (OR = 0.985; CI: 0.976-0.994; p = 0.002); moreover, the GA genotype of rs2167270 was protective against poor glycemic control compared to the GG genotype (OR = 0.417; CI: 0.245-0.712; p = 0.001). Conclusions: Higher serum leptin and the GA genotype of the rs2167270 SNP of the LEP gene were associated with good glycemic control in T2DM patients on metformin therapy. Further studies with a larger sample size from multiple institutions are required to validate the findings.