Systemic evaluation of the relationship between psoriasis, psoriatic arthritis and osteoporosis: observational and Mendelian randomisation study

Shared genetic architecture highlights the bidirectional association between major depressive disorder and fracture risk

Background

There is limited evidence suggesting that osteoporosis might exacerbate depressive symptoms, while more studies demonstrate that depression negatively affects bone density and increases fracture risk.

Aims

To explore the relationship between major depressive disorder (MDD) and fracture risk.

Methods

We conducted a nested case-control analysis (32 670 patients with fracture and 397 017 individuals without fracture) and a matched cohort analysis (16 496 patients with MDD and 435 492 individuals without MDD) in the same prospective UK Biobank data set. Further, we investigated the shared genetic architecture between MDD and fracture with linkage disequilibrium score regression and the MiXeR statistical tools. We used the conditional/conjunctional false discovery rate approach to identify the specific shared loci. We calculated the weighted genetic risk score for individuals in the UK Biobank and logistic regression was used to confirm the association observed in the prospective study.

Results

We found that MDD was associated with a 14% increase in fracture risk (hazard ratio (HR) 1.14, 95% CI 1.14 to 1.15, p<0.001) in the nested case-control analysis, while fracture was associated with a 72% increase in MDD risk (HR 1.72, 95% CI 1.64 to 1.79, p<0.001) in the matched cohort analysis, suggesting a longitudinal and bidirectional relationship. Further, genetic summary data suggested a genetic overlap between MDD and fracture. Specifically, we identified four shared genomic loci, with the top signal (rs7554101) near SGIP1. The protein encoded by SGIP1 is involved in cannabinoid receptor type 1 signalling. We found that genetically predicted MDD was associated with a higher risk of fracture and vice versa. In addition, we found that the higher expression level of SGIP1 in the spinal cord and muscle was associated with an increased risk of fracture and MDD.

Conclusions

The genetic pleiotropy between MDD and fracture highlights the bidirectional association observed in the epidemiological analysis. The shared genetic components (such as SGIP1) between the diseases suggest that modulating the endocannabinoid system could be a potential therapeutic strategy for both MDD and bone loss.

Associations of residential greenness with bone mineral density and osteoporosis: the modifying effect of genetic susceptibility

OBJECTIVES

To investigate the associations of residential greenness with bone mineral density and incident osteoporosis, and further evaluate the potential modifying effect of genetic susceptibility.

METHODS

We used the Normalised Difference Vegetation Index (NDVI) at various buffer distances, including 300 m (NDVI300m), 500 m (NDVI500m), 1000 m (NDVI1000m) and 1500 m (NDVI1500m), to serve as indicators of greenness. We fitted linear regression, logistic regression and Cox proportional hazard models to assess the associations of residential greenness with estimated bone mineral density (eBMD), prevalent osteoporosis and incident osteoporosis, respectively. With the Polygenic Risk Score (PRS) for osteoporosis, we further assessed the joint effects of genetic risk and greenness on the risk of osteoporosis. We conducted causal mediation analyses to explore potential mediators.

RESULTS

Each IQR increase in NDVI300m was associated with 0.0007 (95% CI 0.0002 to 0.0013) increase in eBMD, 6% lower risk of prevalent osteoporosis (OR 0.94; 95% CI 0.92 to 0.97) and 5% lower risk of incident osteoporosis (HR 0.95; 95% CI 0.93 to 0.98). The joint effects of greenness and PRS on the risk of osteoporosis displayed a clear dose-response pattern. Compared with individuals exposed to low NDVI levels and high genetic risk, those exposed to high NDVI levels and low genetic risk had a 56% (95% CI 51% to 61%) lower risk of osteoporosis. The primary mediators in the association between greenness and incident osteoporosis were identified as PM2.5 and NO2.

CONCLUSIONS

Residential greenness was associated with higher bone mineral density and decreased risk of incident osteoporosis.

Deciphering the complex relationship between type 2 diabetes and fracture risk with both genetic and observational evidence

The 'diabetic bone paradox' suggested that type 2 diabetes (T2D) patients would have higher areal bone mineral density (BMD) but higher fracture risk than individuals without T2D. In this study, we found that the genetically predicted T2D was associated with higher BMD and lower risk of fracture in both weighted genetic risk score (wGRS) and two-sample Mendelian randomization (MR) analyses. We also identified ten genomic loci shared between T2D and fracture, with the top signal at SNP rs4580892 in the intron of gene RSPO3. And the higher expression in adipose subcutaneous and higher protein level in plasma of RSPO3 were associated with increased risk of T2D, but decreased risk of fracture. In the prospective study, T2D was observed to be associated with higher risk of fracture, but BMI mediated 30.2% of the protective effect. However, when stratified by the T2D-related risk factors for fracture, we observed that the effect of T2D on the risk of fracture decreased when the number of T2D-related risk factors decreased, and the association became non-significant if the T2D patients carried none of the risk factors. In conclusion, the genetically determined T2D might not be associated with higher risk of fracture. And the shared genetic architecture between T2D and fracture suggested a top signal around RSPO3 gene. The observed effect size of T2D on fracture risk decreased if the T2D-related risk factors could be eliminated. Therefore, it is important to manage the complications of T2D to prevent the risk of fracture.

Low Bone Mineral Density and the Risk of Benign Paroxysmal Positional Vertigo

OBJECTIVE

This study aimed to comprehensively analyze the relationship between low bone mineral density (BMD) and the risk of benign paroxysmal positional vertigo (BPPV) based on the large prospective population-based UK Biobank (UKB) cohort.

STUDY DESIGN

Prospective population-based cohort study.

SETTING

The UKB.

METHODS

This prospective cohort study included UKB participants recruited between 2006 and 2010 who had information on BMD and did not have BPPV before being diagnosed with low BMD. Univariable and multivariable logistic regression models were constructed to assess the association between low BMD (overall low BMD, osteopenia, and osteoporosis) and BPPV. We further conducted sex and age subgroup analysis, respectively. Finally, the effects of antiosteoporosis and female sex hormone medications on BPPV in participants with osteoporosis were evaluated.

RESULTS

In total, 484,303 participants were included in the final analysis, and 985 developed BPPV after a maximum follow-up period of 15 years. Osteoporosis was associated with a higher risk of BPPV (odds ratio [OR] = 1.37, P = .0094), whereas osteopenia was not. Subgroup analyses suggested that the association between osteoporosis and BPPV was significant only in elderly females (≥60 years, OR = 1.51, P = .0007). However, no association was observed between antiosteoporosis or female sex hormone medications and BPPV in the participants with osteoporosis.

CONCLUSION

Osteoporosis was associated with a higher risk of developing general BPPV, especially in females aged ≥ 60 years old, whereas osteopenia was not associated with BPPV.

Biguanide chitosan microneedles with cell-free DNA scavenging ability for psoriasis therapy

High levels of cell-free DNA (cfDNA) induce psoriasis. Currently, the treatment of psoriasis has the disadvantages of penetration difficulty, suppression of normal immunity, and skin irritation. In this study, biguanide chitosan microneedles (BGC-MNs) were prepared to treat psoriasis by removing cfDNA from the dermis through the skin barrier. The effects of chitosan with different bisguanidine contents on DNA-binding capacity, biocompatibility, and inflammation inhibition were compared, revealing that chitosan containing 20% bisguanidine (BGC2) was found to have the best overall performance. In vitro, BGC2 effectively cleared cfDNA and inhibited the production of inflammatory factors. BGC-MN made from BGC2 had good mechanical and solubility properties. In vivo, BGC-MNs cleared cfDNA, reduced the level of inflammatory factors in the dermis, and exerted a good therapeutic effect on mice with psoriasis. These results suggested that BGC-MNs provided a new approach to treating psoriasis in terms of scavenging cfDNA and exerting anti-inflammatory effects.

Causal Relationship Between Immune Cells/Cytokines and Dilated Cardiomyopathy

To date, whether there is any causal relationship between dilated cardiomyopathy (DCM) and the changes in the levels/expression of immune cells/cytokines is still unclear. This study aimed to investigate the causal relationship between the levels of various types of immune cells/cytokines and DCM. Herein, two-sample Mendelian randomization (MR) (TSMR) using R software was conducted. Single nucleotide polymorphisms (SNPs) related to the levels of various types of immune cells/cytokines and DCM were screened based on the genome-wide association studies (GWAS) obtained from open-source databases. The TSMR was conducted using inverse variance weighted (IVW), method, MR-Egger regression, weighted median method, and simple estimator based on mode to explore the causal association between the levels of each immune cell/cytokine and DCM. Sensitivity analysis was conducted using MR-Egger regression and a leave-one-out sensitivity test. A total of 1816 SNPs related to host immune status and DCM were identified. The IVW results showed a relationship between DCM and the circulating levels of basophils/eosinophils, total eosinophils-basophils, lymphocytes, and C-reactive protein (CRP). Increased lymphocytes levels (odds ratio (OR) = 0.91, 95% confidence interval (CI): 0.84-0.97, P = 0.005) were seen as protective against DCM, whereas increased basophil (OR = 1.18, 95% CI: 1.04-1.33, P = 0.022), eosinophil (OR = 1.1, 95% CI: 1.03-1.17, P = 0.007), eosinophil-basophil (OR = 1.09, 95% CI: 1.02-1.17, P = 0.014), and CRP (OR = 1.1, 95% CI: 1.03-1.18, P = 0.013) levels were associated with an increased risk of DCM. These analyses revealed that there may be a relationship between immune cells/select cytokine status and the onset of DCM. Future studies are required to further validate these outcomes in animal models and clinical trials.

Osteoporosis in psoriatic arthritis: Risk factors, insufficiency fractures and its association with the disease activity

OBJECTIVE

The prevalence of osteoporosis (OP) and insufficiency fractures in psoriatic arthritis (PsA) remains controversial. The aim of this study was to describe the prevalence of OP and insufficiency fractures in a representative cohort of patients with PsA, and to analyse its association with general risk factors and characteristics of the psoriatic disease in our geographical area.

METHODS

Multi-centric, descriptive study of patients with PsA. We recorded clinical characteristics, as well as protective and risk factors for OP and insufficiency fractures. Hip and lumbar densitometry and lateral X-ray of the spine were evaluated. Descriptive statistics for OP and risk factors were calculated. The patients with OP were compared to those without by univariate analyses, and results were adjusted by age and sex. The association of OP and fractures with clinical characteristics was analysed by logistic regression.

RESULTS

166 patients (50 men; 116 women) were included. OP was present in 26.5%, and it was more frequent in women and patients above 50 years old. Insufficiency fractures occurred in 5.4% of the total sample. In the logistic regression, OP was associated with age over 50 [OR 3.7; 95% CI (1.2-11.6); p=.02]. No association with clinical parameters was found. The most frequent risk factors among patients with OP were vitamin D insufficiency, sedentary behaviour, low calcium intake, and active smoking. In the logistic regression, OP was associated with early menopause [OR 11.7; 95% CI (1.29-106.0); p=.029] and sedentary behaviour [OR 2.3; 95% CI (1.0-5.2); p=.049].

CONCLUSIONS

In patients with PsA, OP is more frequent in women and patients over 50 years old. A sedentary lifestyle and early menopause may add extra risk for OP. Type, duration disease, and treatments are not associated with OP or insufficiency fractures.

Analysis of the Relationship between Rheumatoid Arthritis and Osteoporosis Based on Mendelian Randomization

BACKGROUND

As the global population ages, the World Health Organization has found a yearly increase in the incidence of rheumatoid arthritis and osteoporosis. This trend poses a challenge to public health and healthcare and calls for the implementation of more preventive and treatment measures to address these health issues.

OBJECTIVE

This study aims to investigate the causal relationship between rheumatoid arthritis (RA) and osteoporosis (OP) using the Mendelian randomization (MR) method.

METHODS

OP diagnosis was based on the gold standard of bone mineral density (BMD). Single nucleotide polymorphisms (SNPs) were identified from the genome-wide association research database formed by RA and BMD, with a parameter setting of P < 5×10-8, chain imbalance r2<0.01, and kb = 10,000. Five complementary MR methods, including inverse variance weighted (IVW), MR-Egger regression, weighted median, simple mode estimation based on mode, and weighted estimation based on mode, were used to evaluate the causal relationship between RA and OP/BMD using odds ratio (OR) values and 95% confidence intervals (CI). Sensitivity analyses were performed using heterogeneity tests, horizontal pleiotropy, and individual rejection tests.

RESULTS

A total of 78 instrumental variables were identified that were closely related to both RA and BMD in mixed populations, while 14 instrumental variables were identified in the European population and 38 instrumental variables were identified in the Asian population. Using IVW as the main analysis method, the MR analysis results of RA and BMD showed the following: mixed population OR = 0.96, 95%CI: 0.93-1.00; European population OR = 0.55, 95%CI: 0.27-1.12; and Asian population OR = 0.95, 95%CI: 0.90-1.01. Sensitivity analyses showed that the MR results were robust.

CONCLUSION

The study found insufficient evidence of a causal relationship between RA and OP/BMD, suggesting that RA may not have a direct effect on OP/BMD.

Management of psoriatic arthritis: a consensus opinion by expert rheumatologists

Background

Psoriatic arthritis (PsA) is a chronic inflammatory musculoskeletal disease involving several articular and extra-articular structures. Despite the important progresses recently made in all of the aspects of this disease, its management is still burdened by unresolved issues. The aim of this exercise was to provide a set of statements that may be helpful for the management of PsA.

Methods

A group of 38 Italian rheumatologists with recognized expertise in PsA selected and addressed the following four topics: "early PsA," "axial-PsA," "extra-articular manifestations and comorbidities," "therapeutic goals." Relevant articles from the literature (2016-2022) were selected by the experts based on a PubMed search. A number of statements for each topic were elaborated.

Results

Ninety-four articles were selected and evaluated, 68 out of the 1,114 yielded by the literature search and 26 added by the Authors. Each of the four topic was subdivided in themes as follows: transition from psoriasis to PsA, imaging vs. CASPAR criteria in early diagnosis, early treatment for "early PsA"; axial-PsA vs. axialspondyloarthritis, diagnosis, clinical evaluation, treatment, standard radiography vs. magnetic resonance imaging for "axial PsA"; influence of inflammatory bowel disease on the therapeutic choice, cardiovascular comorbidity, bone damage, risk of infection for "comorbidities and extra-articular manifestations"; target and tools, treat-to-target strategy, role of imaging for "therapeutic goals." The final document consisted of 49 statements.

Discussion

The final product of this exercise is a set of statements concerning the main issues of PsA management offering an expert opinion for some unmet needs of this complex disease.

Genetic causal relationship between gut microbiome and psoriatic arthritis: a bidirectional two-sample Mendelian randomization study

Background

Several observational studies have suggested a potential relationship between gut microbiome and psoriatic arthritis (PsA). However, the causality of this relationship still remains unclear. We aim to explore if the specific gut microbiome is causally associated with PsA at the genetic level and offer valuable insights into the etiology of PsA.

Methods

In this study, we employed a bidirectional two-sample Mendelian randomization (MR) analysis to investigate the causal effects of the gut microbiome on PsA. Publicly accessible genome-wide association study summary data of gut microbiome were obtained from the MiBioGen consortium (n = 14,306), while the summary statistics of psoriatic arthropathies were sourced from the FinnGen consortium R8 release data (2,776 cases and 221,323 controls). The primary analytical method employed was inverse variance weighted (IVW), complemented by supplementary methods including MR-Egger, weighted median, weighted mode, maximum likelihood, MR-PRESSO, and cML-MA. Reverse MR analysis was performed on the bacteria that were found to be causally associated with PsA in forward MR analysis. Cochran's IVW Q statistic was utilized to assess the heterogeneity of instrumental variables among the selected single nucleotide polymorphisms.

Results

IVW estimates revealed that Ruminococcaceae_UCG-002 (odds ratio (OR) = 0.792, 95% confidence interval (CI), 0.643-0.977, p = 0.029) exhibited a protective effect on PsA. Conversely, Blautia (OR = 1.362, 95% CI, 1.008-1.842, p = 0.044), Eubacterium_fissicatena_group (OR = 1.28, 95% CI, 1.075-1.524, p = 0.006), and Methanobrevibacter (OR = 1.31, 95% CI, 1.059-1.621, p = 0.013) showed a positive correlation with the risk of PsA. No significant heterogeneity, horizontal pleiotropy, or outliers were observed, and the results of the MR analysis remained unaffected by any single nucleotide polymorphisms. According to the results of reverse MR analysis, no significant causal effect of PsA was found on gut microbiome.

Conclusion

This study establishes for the first time a causal relationship between the gut microbiome and PsA, providing potential valuable strategies for the prevention and treatment of PsA. Further randomized controlled trials are urgently warranted to support the targeted protective mechanisms of probiotics on PsA.

Searching for Intrinsic Causality between Colonic Dysbiosis and Non-Ischemic Cardiomyopathy: A Mendelian Randomization-Based Analysis

Objective: Little is known about gut microbiota (GM) and cardiomyopathy. Their causal relationship was explored using two-sample Mendelian randomization (TSMR) performed by R software. Methods: The single nucleotide polymorphisms (SNPs) were further screened based on the genome-wide association studies (GWAS) of gut microbiota and cardiomyopathy obtained from an open database. TSMR was performed using an MR-Egger regression, simple estimator based on mode, weighted median method, inverse variance weighted (IVW), weighted estimator and CML-MA-BIC to explore the causal association. And the sensitivity analysis was carried out using an MR-Egger regression and the leave-one-out sensitivity test. Results: As for 211 GM taxa, IVW results confirmed that the class Actinobacteria (OR = 0.81, p = 0.021) and genus Coprobacter (OR = 0.85, p = 0.033) were protective factors for cardiomyopathy. The phylum Firmicutes (OR = 0.87, p < 0.01), family Acidaminococcaceae (OR = 0.89, p < 0.01), genus Desulfovibrio (OR = 0.92, p = 0.030) and genus Prevotella9 (OR = 0.93, p = 0.029) were protective factors for ischemic cardiomyopathy. The family Rhodospirillaceae (OR = 1.06, p = 0.036) and genus Turicibacter (OR = 1.09, p = 0.019) were risk factors for ischemic cardiomyopathy. The genus Olsenella (OR = 0.91, p = 0.032) was a protective factor for non-ischemic cardiomyopathy. The order Rhodospirillales (OR = 1.14, p = 0.024), family Rikenellaceae (OR = 1.21, p = 0.012) and genus Gordonibacter (OR = 1.12, p = 0.019) were risk factors for non-ischemic cardiomyopathy. The robustness of MR results was reflected in the heterogeneity (p > 0.05) and pleiotropy (p > 0.05) analyses. Conclusions: A potential causal relationship of cardiomyopathy with some GM taxa has been confirmed in the current study.

Ambient PM2.5 Exposure and Bone Homeostasis: Analysis of UK Biobank Data and Experimental Studies in Mice and in Vitro

BACKGROUND

Previous evidence has identified exposure to fine ambient particulate matter (PM 2.5 ) as a leading risk factor for adverse health outcomes. However, to date, only a few studies have examined the potential association between long-term exposure to PM 2.5 and bone homeostasis.

OBJECTIVE

We sought to examine the relationship between long-term PM 2.5 exposure and bone health and explore its potential mechanism.

METHODS

This research included both observational and experimental studies. First, based on human data from UK Biobank, linear regression was used to explore the associations between long-term exposure to PM 2.5 (i.e., annual average PM 2.5 concentration for 2010) and bone mineral density [BMD; i.e., heel BMD (n = 37,440 ) and femur neck and lumbar spine BMD (n = 29,766 )], which were measured during 2014-2020. For the experimental animal study, C57BL/6 male mice were assigned to ambient PM 2.5 or filtered air for 6 months via a whole-body exposure system. Micro-computed tomography analyses were applied to measure BMD and bone microstructures. Biomarkers for bone turnover and inflammation were examined with histological staining, immunohistochemistry staining, and enzyme-linked immunosorbent assay. We also performed tartrate-resistant acid phosphatase (TRAP) staining and bone resorption assay to determine the effect of PM 2.5 exposure on osteoclast activity in vitro. In addition, the potential downstream regulators were assessed by real-time polymerase chain reaction and western blot.

RESULTS

We observed that long-term exposure to PM 2.5 was significantly associated with lower BMD at different anatomical sites, according to the analysis of UK Biobank data. In experimental study, mice exposed long-term to PM 2.5 exhibited excessive osteoclastogenesis, dysregulated osteogenesis, higher tumor necrosis factor-alpha (TNF- α ) expression, and shorter femur length than control mice, but they demonstrated no significant differences in femur structure or BMD. In vitro, cells stimulated with conditional medium of PM 2.5 -stimulated macrophages had aberrant osteoclastogenesis and differences in the protein/mRNA expression of members of the TNF- α / Traf 6 / c -Fos pathway, which could be partially rescued by TNF- α inhibition.

DISCUSSION

Our prospective observational evidence suggested that long-term exposure to PM 2.5 is associated with lower BMD and further experimental results demonstrated exposure to PM 2.5 could disrupt bone homeostasis, which may be mediated by inflammation-induced osteoclastogenesis. https://doi.org/10.1289/EHP11646.

Targeting sulfation-dependent mechanoreciprocity between matrix and osteoblasts to mitigate bone loss

Sulfation is a widespread modification of biomolecules that has been incompletely explored to date. Through cross-phenotype meta-analysis of bone mineral density in up to 426,824 genotyped human participants along with phenotypic characterization of multiple mutant mouse lines, we identified a causative role for sulfate transporter solute carrier family 26 member A2 (SLC26A2) deficiency in osteoporosis. Ablation of SLC26A2 in osteoblasts caused severe bone loss and accumulation of immature bone cells and elicited peculiar pericellular matrix (PCM) production characterized by undersulfation coupled with decreased stiffness. These altered chemophysical properties of the PCM disrupted the formation of focal adhesions in osteoblasts. Bulk RNA sequencing and functional assays revealed that the mechanoreciprocal inhibition of focal adhesion kinase (FAK) and Yes1-associated transcriptional regulator (YAP)/WW domain containing transcription regulator 1 (TAZ) signaling impinged osteoblast maturation upon SLC26A2 deficiency. Moreover, pharmacological abrogation of the Hippo kinases and forced wheel-running ameliorated SLC26A2-deficient osteoporosis by promoting YAP/TAZ activity. Analysis of mouse single-cell RNA sequencing data suggested coordination among sulfate metabolism, focal adhesion, and YAP/TAZ activity during osteoblast-to-osteocyte transition. In addition to the SLC26A2-deficient setting, altered FAK and YAP/TAZ signaling was also observed in bone cells of ovariectomized mice and patients with osteoporosis, and pharmacological enforcing of YAP/TAZ activity ameliorated bone loss in ovariectomized mice. Collectively, these data unveil a role for sulfation in the developmental mechanoreciprocity between matrix and osteoblasts, which could be leveraged to prevent bone loss.

Investigating the association between serum ADAM/ADAMTS levels and bone mineral density by mendelian randomization study

PURPOSE

A Disintegrin and Metalloproteinase (ADAM) and A Disintegrin and Metalloproteinase with Thrombospondin Motif (ADAMTS) have been reported potentially involved in bone metabolism and related to bone mineral density. This Mendelian Randomization (MR) analysis was performed to determine whether there are causal associations of serum ADAM/ADAMTS with BMD in rid of confounders.

METHODS

The genome-wide summary statistics of four site-specific BMD measurements were obtained from studies in individuals of European ancestry, including forearm (n = 8,143), femoral neck (n = 32,735), lumbar spine (n = 28,498) and heel (n = 426,824). The genetic instrumental variables for circulating levels of ADAM12, ADAM19, ADAM23, ADAMTS5 and ADAMTS6 were retrieved from the latest genome-wide association study of European ancestry (n = 5336 ~ 5367). The estimated causal effect was given by the Wald ratio for each variant, the inverse-variance weighted model was used as the primary approach to combine estimates from multiple instruments, and sensitivity analyses were conducted to assess the robustness of MR results. The Bonferroni-corrected significance was set at P < 0.0025 to account for multiple testing, and a lenient threshold P < 0.05 was considered to suggest a causal relationship.

RESULTS

The causal effects of genetically predicted serum ADAM/ADAMTS levels on BMD measurements at forearm, femoral neck and lumbar spine were not statistically supported by MR analyses. Although causal effect of ADAMTS5 on heel BMD given by the primary MR analysis (β = -0.006, -0.010 to 0.002, P = 0.004) failed to reach Bonferroni-corrected significance, additional MR approaches and sensitivity analyses indicated a robust causal relationship.

CONCLUSION

Our study provided suggestive evidence for the causal effect of higher serum levels of ADAMTS5 on decreased heel BMD, while there was no supportive evidence for the associations of ADAM12, ADAM19, ADAM23, and ADAMTS6 with BMD at forearm, femoral neck and lumbar spine in Europeans.

Investigating the causal relationship between ankylosing spondylitis and osteoporosis in the European population: a bidirectional Mendelian randomization study

Background

Ankylosing Spondylitis (AS) is an inflammatory condition affecting the spine, which may lead to complications such as osteoporosis (OP). Many observational studies have demonstrated a close relationship with strong evidence between OP and AS. The combination of AS and OP is already an indisputable fact, but the exact mechanism of AS complicated with OP is unclear. To better prevent and treat OP in patients with AS, it is necessary to understand the specific mechanism of OP in these patients. In addition, there is a study showing that OP is a risk factor for AS, but the causal relationship between them is not yet clear. Therefore, we conducted a bidirectional Mendelian randomization (MR) analysis to determine whether there is a direct causal effect between AS and OP and to investigate the co-inherited genetic information between the two.

Methods

Bone mineral density (BMD) was used as a phenotype for OP. The AS dataset was taken from the IGAS consortium and included people of European ancestry (9,069 cases and 13,578 controls). BMD datasets were obtained from the GEFOS consortium, a large GWAS meta-analysis study, and the UK Biobank and were categorized based on site (total body (TB): 56,284 cases; lumbar spine (LS): 28,498 cases; femoral neck (FN): 32,735 cases; forearm (FA): 8,143 cases; and heel: 265,627 cases) and age (0-15: 11,807 cases; 15-30: 4,180 cases; 30-45: 10,062 cases; 45-60: 18,062 cases; and over 60: 22,504 cases).To obtain the casual estimates, the inverse variant weighted (IVW) method was mainly used due to its good statistical power and robustness. The presence of heterogeneity was evaluated using Cochran's Q test. Pleiotropy was assessed utilizing MR-Egger regression and MR-pleiotropy residual sum and outlier (MR-PRESSO).

Results

Generally, there were no significant causal associations between genetically predicted AS and decreased BMD levels. The results of MR-Egger regression, Weighted Median, and Weighted Mode methods were consistent with those of the IVW method. However, there was a sign of a connection between genetically elevated BMD levels and a decreased risk of AS (Heel-BMD: OR = 0.879, 95% CI: 0.795-0.971, P = 0.012; Total-BMD: OR = 0.948, 95% CI: 0.907-0.990, P = 0.017; LS-BMD: OR = 0.919, 95% CI: 0.861-0.980, P = 0.010). The results were confirmed to be reliable by sensitivity analysis.

Conclusion

This MR study found that the causal association between genetic liability to AS and the risk of OP or lower BMD in the European population was not evident, which highlights the second effect (e.g., mechanical reasons such as limited movement) of AS on OP. However, genetically predicted decreased BMD/OP is a risk factor for AS with a causal relationship, implying that patients with OP should be aware of the potential risk of developing AS. Moreover, OP and AS share similar pathogenesis and pathways.

Association of insulin resistance with bone mineral density in a nationwide health check-up population in China

INTRODUCTION

Insulin resistance (IR) is closely associated with cardio-metabolic diseases. However, the impact of IR on bone mass remains obscure. The present study is to evaluate the association between the triglyceride-glucose (TyG) indicated IR and bone mass in a nationwide health check-up population in China.

METHODS

We conducted a retrospective cross-sectional study including 788,247 participants and a longitudinal cohort study in 8770 participants who had repeated measurements of TyG index and bone mass in at least a 2-year follow-up period. The restricted cubic splines and logistic models were used to analyze the association between IR and bone mass in the cross-sectional study. The Cox model was applied to evaluate the relationship between baseline IR and the subsequent incidence of low bone mass and osteoporosis in the longitudinal study.

RESULTS

In the cross-sectional study, the TyG index had positive correlations with low bone mass, osteoporosis, or both after adjusting for confounding factors (all P < 0.001). In the longitudinal cohort study, the baseline TyG index was significantly associated with the incidence of low bone mass, osteoporosis, or both during the follow-up period, with hazard ratios (HRs) of 1.56 (95 % confidence interval [CI]: 1.25, 1.93, P < 0.05), 1.66 (95%CI: 1.06, 2.59, P < 0.05), and 1.55 (95%CI: 1.27, 1.88, P < 0.05) after adjusting for confounding factors, respectively.

CONCLUSIONS

These results suggest that IR indicated by TyG is significantly associated with an increased risk of low bone mass and osteoporosis. Therefore, bone mass monitoring and early prevention strategies may be needed in individuals with IR to prevent the occurrence of low bone mass and osteoporosis.

Mendelian Randomization Studies in Psoriasis and Psoriatic Arthritis: A Systematic Review

Psoriasis (PSO) and psoriatic arthritis (PSA) are inflammatory diseases with complex genetic and environmental contributions. Although studies have identified environmental and clinical associations with PSO/PSA, causality is difficult to establish. Mendelian randomization (MR) employs the random assortment of genetic alleles at birth to evaluate the causal impact of exposures. We systematically reviewed 27 MR studies in PSO/PSA examining health behaviors, comorbidities, and biomarkers. Exposures, including smoking, obesity, cardiovascular disease, and Crohn's disease, were causal for PSO and PSA, whereas PSO was causally associated with several comorbidities. These findings provide insights that can guide preventive counseling and precision medicine.

Both indirect maternal and direct fetal genetic effects reflect the observational relationship between higher birth weight and lower adult bone mass

BACKGROUND

Birth weight is considered not only to undermine future growth, but also to induce lifelong diseases; the aim of this study is to explore the relationship between birth weight and adult bone mass.

METHODS

We performed multivariable regression analyses to assess the association of birth weight with bone parameters measured by dual-energy X-ray absorptiometry (DXA) and by quantitative ultrasound (QUS), independently. We also implemented a systemic Mendelian randomization (MR) analysis to explore the causal association between them with both fetal-specific and maternal-specific instrumental variables.

RESULTS

In the observational analyses, we found that higher birth weight could increase the adult bone area (lumbar spine, β-coefficient= 0.17, P < 2.00 × 10^-16; lateral spine, β-coefficient = 0.02, P = 0.04), decrease bone mineral content-adjusted bone area (BMCadjArea) (lumbar spine, β-coefficient= - 0.01, P = 2.27 × 10^-14; lateral spine, β-coefficient = - 0.05, P = 0.001), and decrease adult bone mineral density (BMD) (lumbar spine, β-coefficient = - 0.04, P = 0.007; lateral spine; β-coefficient = - 0.03, P = 0.02; heel, β-coefficient = - 0.06, P < 2.00 × 10^-16), and we observed that the effect of birth weight on bone size was larger than that on BMC. In MR analyses, the higher fetal-specific genetically determined birth weight was identified to be associated with higher bone area (lumbar spine; β-coefficient = 0.15, P = 1.26 × 10^-6, total hip, β-coefficient = 0.15, P = 0.005; intertrochanteric area, β-coefficient = 0.13, P = 0.0009; trochanter area, β-coefficient = 0.11, P = 0.03) but lower BMD (lumbar spine, β-coefficient = - 0.10, P = 0.01; lateral spine, β-coefficient = - 0.12, P = 0.0003, and heel β-coefficient = - 0.11, P = 3.33 × 10^-13). In addition, we found that the higher maternal-specific genetically determined offspring birth weight was associated with lower offspring adult heel BMD (β-coefficient = - 0.001, P = 0.04).

CONCLUSIONS

The observational analyses suggested that higher birth weight was associated with the increased adult bone area but decreased BMD. By leveraging the genetic instrumental variables with maternal- and fetal-specific effects on birth weight, the observed relationship could be reflected by both the direct fetal and indirect maternal genetic effects.

The causal impact of childhood obesity on bone mineral density and fracture in adulthood: A two-sample Mendelian randomization study

Observational studies have indicated the associations between obesity with bone mineral density (BMD) and fracture but yield inconsistent results. The impact of childhood obesity on bone health in adulthood is even less clear. The present study adopted the Mendelian randomization methods to determine whether the genetically predicted childhood obesity was causally associated with BMD and the risk of fracture. Genetic variants were extracted from genome-wide association studies (GWAS) to identify childhood obesity loci [IEU open GWAS project: childhood obesity (ID: ieu-a-1096)] and single nucleotide polymorphisms (SNPs) as instrumental variables to investigate causality. We used two-sample univariable Mendelian randomization (MR) to estimate causal relationships between childhood obesity on BMD and fracture subtypes based on SNPs from European samples. To avoid bias, Cochran's Q test and leave-one-out variant analysis were performed. The MR analysis shows strong evidence that childhood obesity is causally associated with eBMD (OR 1.068, 95% CI 1.043–1.095, P &lt; 0.001) and a weak decreased risk of leg fracture (OR 0.9990, 95% CI 0.9981–0.9999, P =0.033) based on the inverse variance weighting (IVW) method. After adjusting for diabetes and adult obesity, the results of eBMD remained the same. The MR analysis revealed sufficient evidence to indicate childhood obesity was causally associated with increased BMD and decreased risk of leg fracture in adults. Childhood obesity could be taken into consideration when assessing eBMD.

Impact of Chronic Inflammation in Psoriasis on Bone Metabolism

Psoriasis is a chronic inflammatory disease of the skin and joints associated with several comorbidities such as arthritis, diabetes mellitus and metabolic syndrome, including obesity, hypertension and dyslipidaemia, Crohn's disease, uveitis and psychiatric and psychological diseases. Psoriasis has been described as an independent risk factor for cardiovascular diseases and thus patients with psoriasis should be monitored for the development of cardiovascular disease or metabolic syndrome. However, there is mounting evidence that psoriasis also affects the development of osteoporosis, an important metabolic disease with enormous clinical and socioeconomic impact. At present, there are still controversial opinions about the role of psoriasis in osteoporosis. A more in depth analysis of this phenomenon is of great importance for affected patients since, until now, bone metabolism is not routinely examined in psoriatic patients, which might have important long-term consequences for patients and the health system. In the present review, we summarize current knowledge on the impact of psoriatic inflammation on bone metabolism and osteoporosis.

General and abdominal obesity operate differently as influencing factors of fracture risk in old adults

To infer the causality between obesity and fracture and the difference between general and abdominal obesity, a prospective study was performed in 456,921 participants, and 10,142 participants developed an incident fracture with follow-up period of 7.96 years. A U-shape relationship was observed between BMI and fracture, with the lowest risk of fracture in overweight participants. The obesity individuals had higher fracture risk when BMD was adjusted, and the protective effect of moderate-high BMI on fracture was mostly mediated by bone mineral density (BMD). However, for abdominal obesity, the higher WCadjBMI (linear) and HCadjBMI (J-shape) were found to be related to higher fracture risk, and less than 30% of the effect was mediated by BMD. By leveraging genetic instrumental variables, it provided additional evidences to support the aforementioned findings. In conclusion, keeping moderate-high BMI might be of benefit to old people in terms of fracture risk, whereas abdominal adiposity might increase risk of fracture.

Secondary Osteoporosis and Metabolic Bone Diseases

Fragility fracture is a worldwide problem and a main cause of disability and impaired quality of life. It is primarily caused by osteoporosis, characterized by impaired bone quantity and or quality. Proper diagnosis of osteoporosis is essential for prevention of fragility fractures. Osteoporosis can be primary in postmenopausal women because of estrogen deficiency. Secondary forms of osteoporosis are not uncommon in both men and women. Most systemic illnesses and organ dysfunction can lead to osteoporosis. The kidney plays a crucial role in maintaining physiological bone homeostasis by controlling minerals, electrolytes, acid-base, vitamin D and parathyroid function. Chronic kidney disease with its uremic milieu disturbs this balance, leading to renal osteodystrophy. Diabetes mellitus represents the most common secondary cause of osteoporosis. Thyroid and parathyroid disorders can dysregulate the osteoblast/osteoclast functions. Gastrointestinal disorders, malnutrition and malabsorption can result in mineral and vitamin D deficiencies and bone loss. Patients with chronic liver disease have a higher risk of fracture due to hepatic osteodystrophy. Proinflammatory cytokines in infectious, autoimmune, and hematological disorders can stimulate osteoclastogenesis, leading to osteoporosis. Moreover, drug-induced osteoporosis is not uncommon. In this review, we focus on causes, pathogenesis, and management of secondary osteoporosis.

High Frequency Ultrasound-Based Evaluation of Clinical Effect of Ephedra-Forsythia-Red Bean Decoction Addition and Subtraction Treatment of Psoriasis Vulgaris

This study aimed to investigate the therapeutic effect of ephedra-forsythia-red bean decoction (a formula of traditional Chinese medicine) addition and subtraction treatment of psoriasis vulgaris based on 22 MHz high-frequency ultrasound, so as to provide reference for the selection of traditional Chinese medicine formulas for psoriasis and the clinical application of ultrasound. 80 patients with psoriasis vulgaris with exterior closing and internal depression syndrome diagnosed and treated in the hospital were divided into an observation group (40 cases) and a control group. Patients in the observation group were received ephedra-forsythia-red bean decoction addition and subtraction; and those in the control group were received traditional Chinese medicine of observation group subtraction of raw ephedra, cinnamomum cassia, addition of fineleaf schizonepeta herb, divaricate saposhnikovia root. 22 MHz high-frequency ultrasonography was also performed. The psoriasis area and severity index (PASI) score and efficacy indicators were compared between the two groups. The results showed that the detection rate of nail malnutrition and psoriasis infiltration in psoriasis by high-frequency ultrasound was significantly higher than that by arthroscopy, and the difference was significant ( $P<0.05$ ). The total PASI score of the two groups after treatment was significantly lower than that before treatment, and the total PASI score of the observation group was lower than that of the control group, and the difference was statistically significant ( $P<0.05$ ). The total effective rate of the observation group (87.5%) was significantly higher than that of the control group (67.5%), and the difference was statistically significant ( $P<0.05$ ). It was found that high-frequency ultrasound can effectively display the condition and prognosis of patients with psoriasis. Ephedra-forsythia-red bean decoction was an effective traditional Chinese medicine formula for the treatment of psoriasis vulgaris.

Trends in fractures in patients with spondyloarthritis: a nationwide population-based study (TREND-EspA study)

Our aim was to analyze trends in fracture rates in SpA patients over an extended time period. Only an increase of axial fractures, more specifically vertebral fractures, is observed in SpA.

PURPOSE

To analyze fracture incidence and trend in patients with spondyloarthritis (SpA) over an extended time period.

METHODS

Retrospective observational population-based study with matched cohorts. Data from the Minimum Basic Data Set (MBDS) of Spain were reviewed. All SpA patient hospitalizations reported from 1999 to 2015 (SpA cohort) were analyzed. A control cohort (non-SpA cohort) matched by age, sex, region, and year of hospitalization was recruited. The age and sex-adjusted crude incidence rate was calculated for any fractures (axial and peripheral). Generalized linear models (GLM) were used for trend analysis. Association between fracture type and SpA (and its subtypes) was assessed using unconditional logistic regression models.

RESULTS

In the SpA cohort, the age and sex-adjusted rates per 100,000 inhabitants/year of total fracture and different types of fracture were 45.72 any fractures, 17.64 axial, and 28.02 peripheral; 29.42 osteoporotic (12.67 vertebra, 12.29 hip, 1.50 pelvis, 1.82 humerus and 2.09 radius). In the non-SpA cohort, they were 65.79 any, 12.08 axial, 51.52 peripheral; 31.17 osteoporotic (4.94 vertebra, 16.15 hip, 2.29 pelvis, 3.64 humerus, 5.38 radius). Between 1999 and 2015, the trend in incidence rate for total fracture and different types of fracture increased similarly for both cohorts. In the SpA cohort, an increase of axial fractures was found (AOR 1.444; 95%CI 1.297-1.609), and specifically of vertebral fractures (AOR 2.440; 95%CI 2.097-2.839). Other types of fractures did not increase.

CONCLUSIONS

Only an increase of axial fractures, more specifically vertebral fractures, is observed in SpA. Trend in incidence is similar in both cohorts.

Observational and genetic evidence highlight the association of human sleep behaviors with the incidence of fracture

We combined conventional evidence from longitudinal data in UK Biobank and genetic evidence from Mendelian randomization (MR) approach to infer the causality between sleep behaviors and fracture risk. We found that participants with insomnia showed 6.4% higher risk of fracture (hazard ratio [HR] = 1.064, 95% CI = 1.038-1.090, P = 7.84 × 10^-7), falls and bone mineral density (BMD) mediated 24.6% and 10.6% of the intermediary effect; the MR analyses provided the consistent evidence. A U-shape relationship was observed between sleep duration and fracture risk (P < 0.001) with the lowest risk at sleeping 7-8 h per day. The excessive daytime sleepiness and "evening" chronotype were associated with fracture risk in observational study, but the association between chronotype and fracture did not show in MR analyses. We further generated a sleep risk score (SRS) with potential risk factors (i.e., insomnia, sleep duration, chronotype, and daytime sleepiness). We found that the risk of fracture increased with an increasing SRS (HR = 1.087, 95% CI = 1.065-1.111, P = 1.27 × 10^-14). Moreover, 17.4% of the fracture cases would be removed if all participants exhibited a healthy sleep pattern. In conclusion, insomnia had a causal effect on fracture, falls had a larger intermediary effect than BMD in this association. Individuals with fracture risk could benefit from the intervention on unhealthy sleep pattern.

The association between psoriasis and psoriatic arthritis with the risk of osteoporosis, osteopenia and bone fractures: A systematic review and meta-analysis

BACKGROUND AND AIMS

The possible association between psoriatic/psoriatic arthritis (PsA) and bone loss has been observed; however, studies have yielded inconclusive results. This meta-analysis aimed to assess whether there is an increase in the risk of osteoporosis, osteopenia and fractures in patients with psoriasis/PsA, compared with healthy individuals.

METHODS

PubMed and Scopus were systematically searched from their inception to September 2020 to identify relevant studies. Relative risk, hazard ratio or odds ratio (OR), with their corresponding 95% confidence intervals (95% CI) were calculated and pooled using a random-effects model.

RESULTS

A total of 12 different studies, with a total of 199 389 296 participants, were included. Overall, no significant relationship was observed between psoriasis/PsA and the risk of osteoporosis (psoriasis: OR = 1.28, 95%CI = 0.86-1.90; PsA: OR = 1.32, 95%CI = 0.79-2.19) and osteopenia (psoriasis: OR = 1.50, 95%CI = 0.75-3.02; PsA: OR = 1.61, 95%CI = 0.67-3.85). However, in the subgroup analysis, psoriasis was significantly associated with an increased risk of osteoporosis in men (OR = 1.27, 95%CI = 1.02-1.59) and studies with cohort design (OR = 1.04, 95%CI = 1.003-1.09). Psoriasis was also related to the risk of osteopenia in studies on a combination of both genders (OR = 2.86, 95%CI = 2.70-3.02). The pooled analysis demonstrated a significantly higher risk of fractures among patients with psoriasis (OR = 1.29, 95%CI = 1.02-1.63) and PsA (OR = 2.88, 95%CI = 1.51-5.48), compared with participants without psoriasis/PsA.

CONCLUSIONS

Patients with psoriasis/PsA have an increased risk of fractures. There is little evidence supporting the relation of psoriasis to osteoporosis/osteopenia.

Risk factors associated with osteoporosis and fracture in psoriatic arthritis

BACKGROUND

Although there are few studies mentioned there may be some relationship between psoriatic arthritis (PsA) and osteoporosis, clinical data in real world still need to be clarified in China. The aim of this study was to assess the areal and volumetric bone mineral density (BMD), frequency of fracture, and risk factors in patients with PsA.

METHODS

A total of one hundred PsA patients who visited Peking University First Hospital and one hundred age- and sex-matched healthy controls with DXA data were enrolled in the study. Patients with clinical fractures confirmed by X-ray during follow-up were also recorded. Clinical characteristics of the patients were recorded and compared between the abnormal BMD group and the normal BMD group, as well as between the fracture and non-fracture groups. Risk factors for fracture and low BMD were analyzed.

RESULTS

Mean BMD at the total hip and femoral neck was significantly lower in PsA patients than that in healthy controls (0.809 ± 0.193 vs. 0.901 ± 0.152 g/cm2, P  = 0.041; 0.780 ± 0.146 vs. 0.865 ± 0.166 g/cm2, P  = 0.037, respectively). Moreover, lumbar spine BMD was negatively correlated with psoriasis duration, swollen joint count and DAS28-CRP (r = -0.503, -0.580, -0.438; P < 0.05). Total hip BMD and femoral neck BMD were negatively correlated with HAQ (r = -0.521, -0.335; P < 0.05). Fractures occurred in 29 patients during the follow-up period. Logistic regression analysis showed that older age (OR 1.132 [95%CI: 1.026-1.248), P < 0.05], higher HAQ score (OR 1.493, 95%CI: 1.214-1.836, P < 0.01), higher disease activity index for psoriatic arthritis (OR 1.033, 95% CI: 1.002-1.679, P < 0.05) and hip joint involvement (OR 6.401, 95% CI: 4.012-44.180, P < 0.05) were risk factors for fracture in the multivariate model.

CONCLUSIONS

Increased risks of osteoporosis and fracture were found in PsA patients compared to healthy controls. Besides age, high disease activity and hip joint involvement were risk factors for decreased BMD and fracture.

MiR-133a delivery to osteoblasts ameliorates mechanical unloading-triggered osteopenia progression in vitro and in vivo

Mechanical unloading-induced bone loss is a clinical challenge, and deep understanding for this disease is necessary for developing novel and effective therapies. MicroRNAs (miRNAs) are small non-coding RNAs, and involved in bone remodeling. In the study, we attempted to explore the potential of miR-133a in regulating osteoblast activation and its anti-osteopenia function both in vitro and in vivo. Our in vitro studies at first showed that miR-133a could significantly promote the expression of osteocalcin (OCN), Collagen I, alkaline phosphatase (ALP), runt-related transcription factor 2 (Runx2) and osterix (Osx), promoting the activation and mineralization of osteoblasts. Then, hindlimb unloading (HU)-challenged mice were established with or without intravenous injection of agomir-miR-133a using an osteoblast-targeting delivery system. We found that miR-133a in osteoblasts significantly alleviated the bone loss, microstructural, and biomechanical property in mice with mechanical unloading, contributing to osteopenia alleviation. Furthermore, both in vitro and in vivo experiments showed that miR-133a could restrain osteoclastogenesis via tartrate-resistant acid phosphatase (TRAP) staining. In conclusion, our results suggested that miR-133a may be a promising factor in mediating the occurrence and progression of osteopenia caused by mechanical unloading, and thus targeting miR-133a could be considered as an effective therapeutic strategy for the suppression of pathological osteopenia.

Twelve years of GWAS discoveries for osteoporosis and related traits: advances, challenges and applications

Osteoporosis is a common skeletal disease, affecting ~200 million people around the world. As a complex disease, osteoporosis is influenced by many factors, including diet (e.g. calcium and protein intake), physical activity, endocrine status, coexisting diseases and genetic factors. In this review, we first summarize the discovery from genome-wide association studies (GWASs) in the bone field in the last 12 years. To date, GWASs and meta-analyses have discovered hundreds of loci that are associated with bone mineral density (BMD), osteoporosis, and osteoporotic fractures. However, the GWAS approach has sometimes been criticized because of the small effect size of the discovered variants and the mystery of missing heritability, these two questions could be partially explained by the newly raised conceptual models, such as omnigenic model and natural selection. Finally, we introduce the clinical use of GWAS findings in the bone field, such as the identification of causal clinical risk factors, the development of drug targets and disease prediction. Despite the fruitful GWAS discoveries in the bone field, most of these GWAS participants were of European descent, and more genetic studies should be carried out in other ethnic populations to benefit disease prediction in the corresponding population.

Osteoporosis in Inflammatory Arthritides: New Perspective on Pathogenesis and Treatment

Osteoporosis is a skeletal disorder characterized by impaired bone strength and increased risk of fragility fracture and is among the most relevant comorbidities of rheumatic diseases. The purpose of the present review is to discuss the pathogenesis of local and systemic bone involvement in inflammatory arthritides, especially Rheumatoid Arthritis, Psoriatic Arthritis, and Spondyloarthritides, as well as the effect of anti-rheumatic treatments and anti-osteoporotic medication on bone health and fracture incidence, including recent data on novel therapeutic perspective.