Long-Term Treatment With TNF-Alpha Inhibitors Improves Bone Mineral Density But Not Vertebral Fracture Progression in Ankylosing Spondylitis

Improvement of bone mineral density and new vertebral fractures during 8 years of TNF-α inhibition in patients with axial spondyloarthritis

OBJECTIVE

In our prospective cohort with standardized bi-annual measurements of bone mineral density (BMD) and spinal radiographs, we evaluated the long-term course of BMD and the development of radiographic vertebral fractures (VFs) during 8 years of TNFi treatment in patients with radiographic axial spondyloarthritis (r-axSpA).

METHODS

Consecutive axSpA patients from the GLAS cohort receiving TNFi for ≥8 years were included. Patients who received anti-osteoporotic treatment were excluded. Lumbar spine (LS) BMD was assessed at baseline, 1 year and bi-annually using DEXA. Radiographic VFs were evaluated using the Genant classification.

RESULTS

126 axSpA patients were included; 75 % male, mean age 42 ± 11 years, ASDAS 3.8 ± 0.8, median LS BMD Z-score -0.5 (IQR -1.4-0.7) and 20 % had radiographic VFs at baseline. Disease activity improved rapidly and sustained. LS BMD Z-score improved significantly up to 4 years compared to the previous time point and sustained thereafter. Median percentage of improvement compared to baseline was 8.9 % (2.8-15.8) and 7.2 % (2.2-14.7) after 4 and 8 years, respectively. Of 90 patients with baseline and 8-year radiographs, 14 (16 %) developed new VFs and 5 (6 %) showed an increase in severity of existing VFs. Of all 44 VFs present at 8 years, 30 % were grade 2 (n = 12) or grade 3 (n = 1).

CONCLUSION

In r-axSpA patients treated with TNFi for 8 years, LS BMD Z-score increased significantly, especially during the first 4 year of treatment. Radiographic VFs continued to develop or progressed, irrespective of improvement in BMD. Therefore, clinical attention for trabecular bone loss is important in daily clinical practice.

Osteoporosis and fracture risk are multifactorial in patients with inflammatory rheumatic diseases

Patients with inflammatory rheumatic and musculoskeletal diseases (iRMDs) such as rheumatoid arthritis, connective tissue diseases, vasculitides and spondyloarthropathies are at a higher risk of osteoporosis and fractures than are individuals without iRMDs. Research and management recommendations for osteoporosis in iRMDs often focus on glucocorticoids as the most relevant risk factor, but they largely ignore disease-related and general risk factors. However, the aetiopathogenesis of osteoporosis in iRMDs has many facets, including the negative effects on bone health of local and systemic inflammation owing to disease activity, other iRMD-specific risk factors such as disability or malnutrition (for example, malabsorption in systemic sclerosis), and general risk factors such as older age and hormonal loss resulting from menopause. Moreover, factors that can reduce fracture risk, such as physical activity, healthy nutrition, vitamin D supplementation and adequate treatment of inflammation, are variably present in patients with iRMDs. Evidence relating to general and iRMD-specific protective and risk factors for osteoporosis indicate that the established and very often used term 'glucocorticoid-induced osteoporosis' oversimplifies the complex inter-relationships encountered in patients with iRMDs. Osteoporosis in these patients should instead be described as 'multifactorial'. Consequently, a multimodal approach to the management of osteoporosis is required. This approach should include optimal control of disease activity, minimization of glucocorticoids, anti-osteoporotic drug treatment, advice on physical activity and nutrition, and prevention of falls, as well as the management of other risk and protective factors, thereby improving the bone health of these patients.

The prevalence of vertebral fractures in diffuse idiopathic skeletal hyperostosis and ankylosing spondylitis: A systematic review and meta-analysis

Background

Subjects with ankylosing spinal disorders, including diffuse idiopathic skeletal hyperostosis (DISH) and ankylosing spondylitis (AS) are more prone to vertebral fractures and frequently present with neurological deficit compared to the patients without an ankylosed spine. Moreover, prevalent vertebral fractures are an important predictor for subsequent fracture risk. However, the pooled fracture prevalence for DISH is unknown and less recent for AS. We aimed to systematically investigate the prevalence and risk of vertebral fractures in DISH and AS populations.

Methods

Publications in Medline and EMBASE were searched from January 1980 until July 2023 for cohort studies reporting vertebral fractures in AS and DISH. Data on prevalence were pooled with random effects modeling after double arcsine transformation. Heterogeneity was assessed with I2 statistics and we performed subgroup analysis and meta-regression to explore sources of heterogeneity.

Results

We included 7 studies on DISH (n = 1,193, total fractures = 231) with a pooled vertebral fracture prevalence of 22.6% (95%CI: 13.4%-33.4%). For AS, 26 studies were included (n = 2,875, total fractures = 460) with a pooled vertebral fracture prevalence of 15.2% (95%CI: 11.6%-19.1%). In general, fracture prevalence for AS remained similar for several study-level and clinically relevant characteristics, including study design, diagnostic criteria, spine level, and patient characteristics in subgroup analysis. AS publications from 2010 to 2020 showed higher fracture prevalence compared to 1990 to 2010 (18.6% vs. 11.6%). Fractures in DISH were most common at the thoracolumbar junction, whereas for AS, the most common location was the mid-thoracic spine.

Conclusions

Vertebral fractures are prevalent in AS and DISH populations. Differences in fracture distribution along the spinal axis exist between the 2 disorders. Additional longitudinal studies are needed for incident fracture assessment in patients with ankylosing spinal disorders.

Cytokines: The links between bone and the immune system

Osteoporosis results from an imbalance in a highly balanced physiological process called bone remodeling, in which osteoclast-mediated bone resorption and osteoblast-mediated bone formation play important roles. Osteoimmunology is a newly discovered interdisciplinary research field that focuses on the relationship between bone and the immune system. Specifically, bone and the immune system interact through cytokines, immune cells secrete cytokines, and cytokines finely regulate bone metabolism by mediating the differentiation and activity of osteoclasts and osteoblasts. Therefore, understanding the influence of cytokines on bone metabolism is conducive for the development of novel targeted drugs against immune-related bone diseases. This review summarizes the pathophysiological functions of various common cytokines in bone and discusses the potential clinical value of multiple cytokines in immune-mediated bone diseases.

Pathogenesis, assessment, and management of bone loss in axial spondyloarthritis

INTRODUCTION

Axial spondyloarthritis (axSpA) presents a complex scenario where both new bone formation in entheseal tissues and significant trabecular bone loss coexist, emphasizing the intricate nature of bone dynamics in this context.

METHODS

A search of the literature was conducted to compose a narrative review exploring the pathogenesis, possible assessment methods, and potential management options for axSpA.

RESULTS

While chronic systemic and local inflammation contribute to bone loss, the mechanisms behind axSpA-associated bone loss exhibit distinct characteristics influenced by factors like mechanical stress and the gut microbiome. These factors directly or indirectly stimulate osteoclast differentiation and activation through the RANK-RANKL axis, while simultaneously impeding osteoblast differentiation via negative regulation of bone anabolic pathways, including the Wnt signaling pathway. This disruption in the balance between bone-resorbing osteoclasts and bone-forming osteoblasts contributes to overall bone loss in axSpA. Early evaluation at diagnosis is prudent for detecting bone changes. While traditional dual x-ray absorptiometry (DXA) has limitations due to potential overestimation from spinal new bone formation, alternative methods like trabecular bone score (TBS), quantitative CT (QCT), and quantitative ultrasound (QUS) show promise. However, their integration into routine clinical practice remains limited. In addition to approved anti-inflammatory drugs, lifestyle adjustments like regular exercise play a key role in preserving bone health. Tailoring interventions based on individual risk profiles holds potential for mitigating bone loss progression.

CONCLUSION

Recognizing the pivotal role of bone loss in axSpA underscores the importance of integrating regular assessments and effective management strategies into clinical practice. Given the multifaceted contributors to bone loss in axSpA, a multidisciplinary approach is essential.

DNA methylation-mediated Rbpjk suppression protects against fracture nonunion caused by systemic inflammation

Challenging skeletal repairs are frequently seen in patients experiencing systemic inflammation. To tackle the complexity and heterogeneity of the skeletal repair process, we performed single-cell RNA sequencing and revealed that progenitor cells were one of the major lineages responsive to elevated inflammation and this response adversely affected progenitor differentiation by upregulation of Rbpjk in fracture nonunion. We then validated the interplay between inflammation (via constitutive activation of Ikk2, Ikk2ca) and Rbpjk specifically in progenitors by using genetic animal models. Focusing on epigenetic regulation, we identified Rbpjk as a direct target of Dnmt3b. Mechanistically, inflammation decreased Dnmt3b expression in progenitor cells, consequently leading to Rbpjk upregulation via hypomethylation within its promoter region. We also showed that Dnmt3b loss-of-function mice phenotypically recapitulated the fracture repair defects observed in Ikk2ca-transgenic mice, whereas Dnmt3b-transgenic mice alleviated fracture repair defects induced by Ikk2ca. Moreover, Rbpjk ablation restored fracture repair in both Ikk2ca mice and Dnmt3b loss-of-function mice. Altogether, this work elucidates a common mechanism involving a NF-κB/Dnmt3b/Rbpjk axis within the context of inflamed bone regeneration. Building on this mechanistic insight, we applied local treatment with epigenetically modified progenitor cells in a previously established mouse model of inflammation-mediated fracture nonunion and showed a functional restoration of bone regeneration under inflammatory conditions through an increase in progenitor differentiation potential.

Trends in Fracture Rates Over Two Decades Among Veterans With Ankylosing Spondylitis

OBJECTIVE

There is an increased risk of fracture in individuals with ankylosing spondylitis (AS) compared to the general population, possibly due to systemic inflammatory effects. The use of tumor necrosis factor inhibitors (TNFi) may reduce fracture risk by inhibiting inflammation. We assessed fracture rates in AS versus non-AS comparators and whether these rates have changed since the introduction of TNFi.

METHODS

We used the national Veterans Affairs database to identify adults ≥18 years old with ≥1 International Classification of Diseases, Ninth Revision (ICD-9)/ICD-10 code for AS and at least 1 disease-modifying antirheumatic drug prescription. As comparators, we selected a random sample of adults without AS diagnosis codes. We calculated fracture incidence rates for AS and comparators, with direct standardization to the cohort structure in 2017. To compare fracture rates from 2000 to 2002 (pre-TNFi) versus 2004-2020 (TNFi era), we performed an interrupted time series analysis.

RESULTS

We included 3,794 individuals with AS (mean age 53 years, 92% male) and 1,152,805 comparators (mean age 60 years, 89% male). For AS, the incidence rate of fractures increased from 7.9/1,000 person-years in 2000 to 21.6/1,000 person-years in 2020. The rate also increased among comparators, although the ratio of fracture rates (AS/comparators) remained relatively stable. In the interrupted time series, the fracture rate for AS patients in the TNFi era was nonsignificantly increased compared to the pre-TNFi era.

CONCLUSION

Fracture rates have increased over time for both AS and non-AS comparators. The fracture rate in individuals with AS did not decrease after TNFi introduction in 2003.

The Association of Calcium Signaling Pathway Gene Variants, Bone Mineral Density and Mild Cognitive Impairment in Elderly People

The association of calcium signaling pathway gene variants, bone mineral density (BMD) and mild cognitive impairment (MCI) is poorly understood so far. A total of 878 participants from Qingdao city were recruited in this study. According to the candidate gene selection method, 58 single nucleotide polymorphisms (SNPs) in eight calcium signaling genes were selected. The association between gene polymorphisms and MCI was revealed by using multiple genetic models. Polygenic risk scores (PRS) were used to summarize the effects of the whole gene. Logistic regression was used to analyze the association between each PRS and MCI. The multiplicative interaction term in the regression models was used to estimate the interaction effects between the PRS and BMD. We observed significant associations of rs6877893 (NR3C1), rs6448456 (CCKAR), and rs723672 (CACNA1C) polymorphisms with MCI. The PRSs of NR3C1 (OR = 4.012, 95% CI = 1.722-9.347, p < 0.001), PRKCA (OR = 1.414, 95% CI = 1.083-1.845, p = 0.011) and TRPM1 (OR = 3.253, 95% CI = 1.116-9.484, p = 0.031) were associated with an increased risk of developing MCI, and the PRS of total genes (OR = 0.330, 95% CI = 0.224-0.485, p < 0.001) was associated with a decreased risk of developing MCI. In interaction effect analysis, the interaction effect of PRKCA and BMD was significant. Genetic variations of the calcium signaling pathway were associated with MCI in older people. There was an interaction effect between PRKCA gene variants and BMD on MCI.

Vertebral Bone Mineral Density, Vertebral Strength, and Syndesmophyte Growth in Ankylosing Spondylitis: The Importance of Bridging

OBJECTIVE

To examine the relationship between vertebral trabecular bone mineral density (tBMD), vertebral strength, and syndesmophytes in patients with ankylosing spondylitis (AS) using quantitative computed tomography (QCT).

METHODS

We performed QCT of the spine to measure syndesmophytes and tBMD in 5 vertebrae (T11-L3) in 61 patients with AS. Finite element analysis was performed to measure vertebral strength in compressive overload, including in trabecular and cortical compartments. In cross-sectional analyses, we examined associations of syndesmophyte height with tBMD and vertebral strength in each vertebra. In 33 patients followed up for 2 years, we investigated whether baseline tBMD and vertebral strength predicted syndesmophyte growth in the same vertebra, and vice versa.

RESULTS

In the cross-sectional analyses, 126 vertebrae had bridging, 77 vertebrae had nonbridging syndesmophytes, and 83 vertebrae had no syndesmophytes. There were strong inverse associations between syndesmophyte height and tBMD, total strength, and trabecular strength only among bridged vertebrae. In the longitudinal analysis, nonbridged vertebrae with low tBMD (adjusted β = -0.01 [95% confidence interval (95% CI) -0.019, -0.0012]) and low strength (adjusted β = -0.0003 [95% CI -0.0004, -0.0002]) had more syndesmophyte growth over time. Similar associations were absent among bridged vertebrae. Conversely, vertebrae with bridging at baseline had a significant loss in percent tBMD over time (adjusted β = -0.001 [95% CI -0.0017, -0.0004]).

CONCLUSION

Associations between syndesmophytes and vertebral density and strength in AS differ between bridged and nonbridged vertebrae. Among nonbridged vertebrae, low tBMD and strength are associated with syndesmophyte growth. Bridging is associated with large subsequent losses in tBMD, possibly due to mechanical offloading.

A brief human history of ankylosing spondylitis: A scoping review of pathogenesis, diagnosis, and treatment

Background:

Ankylosing spondylitis (AS) is a chronic, progressive, inflammatory disease of the spine and SI joints. Diagnostic criteria and treatments have continued to evolve, necessitating a historical compendium of AS and its management. This paper aims to review the historical context underlying the discovery of AS, as well as the major diagnostic and therapeutic discoveries in the last two centuries.

Methods:

A scoping review of the literature pertaining to AS was performed via the Pubmed, Scopus, and Web of Science databases. Future directions of AS treatments were assessed by querying the clinicaltrials.gov website.

Results:

The history of AS can be traced as far back as ancient Egypt (as evidenced by the discovery of its presence in ancient Egyptian mummies) to the late 20^th century, when the inherited nature of AS was linked to a genetic factor, HLA-B27. Each discovery made throughout the years led to further investigations into the pathophysiology, diagnosis, and treatment of AS. The criteria to differentiate AS from rheumatoid arthritis were first reported in 1893. Since then, diagnostic criteria for AS have undergone a series of changes before the present-day diagnostic criteria for AS were ultimately determined in 2009 by the Assessment of Spondyloarthritis International Society.

Conclusion:

As the pathophysiology of AS is better understood, healthcare providers are able to diagnose and treat the condition more effectively. In particular, earlier diagnosis and multiple treatment options have facilitated efficient and more effective treatment.

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.

Efficacy of thunder-fire moxibustion in treating ankylosing spondylitis of kidney deficiency and governor meridian cold and its influence on TNF-α and RANKL: study protocol for a prospective, nonblinded, single-center, randomized controlled trial

Background

Ankylosing spondylitis (AS) is a common chronic inflammatory spondyloarthropathy. It is considered in traditional Chinese medicine (TCM) that the pathogenesis of AS is mainly due to Yang deficiency of kidney governor meridian and internal prosperity of cold evil. Thunder-fire moxibustion is a kind of moxibustion that is characterized in abundance in drug composition, high heat radiation, and strong penetration. Thunder-fire moxibustion on the spinal segment of the governor meridian in treating AS seems compatible with the main pathogenesis of kidney deficiency and governor meridian cold. The trial aims to explore the efficacy of thunder-fire moxibustion in patients with AS of kidney deficiency and governor meridian cold and its influence on bone metabolism, through a prospective randomized trial.

Methods

Sixty patients with AS of kidney deficiency and governor meridian cold will be recruited and randomly assigned to the treatment group (thunder-fire moxibustion three times a week plus basic treatment) and the control group (basic treatment) at the Center of TCM of Beijing Luhe Hospital Affiliated to Capital Medical University (Beijing, China). Each patient will be treated for 4 weeks. The primary outcome is the efficacy of TCM syndrome, and the secondary outcome indexes will include the Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Spondylitis Functional Index (BASFI), Short-Form-36 Questionnaire (SF-36), tumor necrosis factor-α (TNF-α), and receptor activator of nuclear factor-κB ligand (RANKL). TNF-α and RANKL with observation will be determined once respectively before and after treatment, while the other indexes will be observed once prior to the treatment, 2 weeks post-treatment, and at the end of the treatment. Side effects will be recorded and analyzed as well. Inter-group comparison and analysis will be performed based on the intention-to-treat set and per-protocol set.

Discussion

This prospective randomized trial will help verify the efficacy of thunder-fire moxibustion in treating AS of kidney deficiency and governor meridian cold, discuss preliminarily its mechanism in treating this disease, and provide high-quality evidences for scientific researches on clinical treatment with thunder-fire moxibustion against AS.

Trial registration

Chinese Clinical Trial Registry ChiCTR2100044227. Registered on 12 March 2021

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-022-06227-7.

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.

Regulation of TNF-Induced Osteoclast Differentiation

Increased osteoclast (OC) differentiation and activity is the critical event that results in bone loss and joint destruction in common pathological bone conditions, such as osteoporosis and rheumatoid arthritis (RA). RANKL and its decoy receptor, osteoprotegerin (OPG), control OC differentiation and activity. However, there is a specific concern of a rebound effect of denosumab discontinuation in treating osteoporosis. TNFα can induce OC differentiation that is independent of the RANKL/RANK system. In this review, we discuss the factors that negatively and positively regulate TNFα induction of OC formation, and the mechanisms involved to inform the design of new anti-resorptive agents for the treatment of bone conditions with enhanced OC formation. Similar to, and being independent of, RANKL, TNFα recruits TNF receptor-associated factors (TRAFs) to sequentially activate transcriptional factors NF-κB p50 and p52, followed by c-Fos, and then NFATc1 to induce OC differentiation. However, induction of OC formation by TNFα alone is very limited, since it also induces many inhibitory proteins, such as TRAF3, p100, IRF8, and RBP-j. TNFα induction of OC differentiation is, however, versatile, and Interleukin-1 or TGFβ1 can enhance TNFα-induced OC formation through a mechanism which is independent of RANKL, TRAF6, and/or NF-κB. However, TNFα polarized macrophages also produce anabolic factors, including insulin such as 6 peptide and Jagged1, to slow down bone loss in the pathological conditions. Thus, the development of novel approaches targeting TNFα signaling should focus on its downstream molecules that do not affect its anabolic effect.

TNF-Polarized Macrophages Produce Insulin-like 6 Peptide to Stimulate Bone Formation in Rheumatoid Arthritis in Mice

The risk of osteoporosis is increased in rheumatoid arthritis (RA). Anti-tumor necrosis factor (TNF) therapy has markedly improved the outcomes of RA patients but does not improve osteoporosis in some reports. This could be a combined result of disease severity and other therapeutic agents, such as glucocorticoids that accelerate osteoporosis progression. We evaluated the effects of anti-TNF therapy on osteoporosis in an animal model of RA and explored the possible mechanisms involved. Six-week-old TNF transgenic (TNF-Tg) mice with early stage erosive arthritis were treated with TNF antibody (Ab) or control immunoglobulin (IgG) weekly for 4 weeks. We found that TNF Ab completely blocked the development of erosive arthritis in TNF-Tg mice, but only slightly increased vertebral bone mass, associated with reduction in parameters of both bone resorption and formation. Similarly, TNF Ab slightly increased trabecular bone mass in tibias of 8-month-old TNF-Tg mice with advanced erosive arthritis. Interestingly, TNFα increased osteoblast differentiation from mouse bone marrow stromal cells (BMSCs) containing large number of macrophages but not from pure mesenchymal progenitor cells (MPCs). TNFα-polarized macrophages (TPMs) did not express iNos and Arginase 1, typical markers of inflammatory and resident macrophages. Interestingly, TPMs stimulated osteoblast differentiation, unlike resident and inflammatory macrophages polarized by IL-4 and interferon-λ, respectively. RNA-seq analysis indicated that TPMs produced several anabolic factors, including Jagged1 and insulin like 6 (INSL6). Importantly, inhibition of either Jagged1 or INSL6 blocked TNFα-induced osteoblast differentiation. Furthermore, INSL6 Ab significantly decreased the expansion of TNF-induced MPCs in BMSCs, and anti-TNF Ab reduced INSL6 expression by macrophages in vitro and in TNF-Tg mice in vivo. We conclude that TPMs produce INSL6 to stimulate bone formation and anti-TNF Ab blocks not only enhanced bone resorption but also the anabolic effect of TPMs on bone, limiting its effect to increase bone mass in this model of RA. © 2021 American Society for Bone and Mineral Research (ASBMR).

Trends in hospitalizations for vertebral compression fracture in ankylosing spondylitis: data from the National Inpatient Sample 2000-2014

Ankylosing spondylitis (AS) patients are at increased risk of vertebral compression fractures (VCF). Our objective was to examine the yearly trend of VCF hospitalizations in AS patients as compared to rheumatoid arthritis (RA) and the general population. National Inpatient Sample (NIS) database (2000-2014) was used to identify adult (≥ 18 years) hospitalizations, based on validated ICD-9 diagnosis codes. The rate of VCF hospitalizations, as a primary diagnosis, was assessed in three mutually exclusive groups: AS, RA, and the general population. The prevalence of VCF hospitalization was highest in AS (2.70%), compared to 0.77% in RA and 0.35% in the general population. Over the 15-year period, VCF hospitalization in AS was noted to have an increasing trend (Annual Percent Change (APC) = 4.73, p < 0.05) in contrast to the stable trend in the general population (APC = 0.34, p = NS) and a declining trend in RA (APC -3.61, p < 0.05). VCF related to AS was also associated with a longer hospital stay as compared to the general population (8.1 days vs. 5.1 days, p < 0.05) and higher inpatient mortality (3.4% vs. 1.0%, p < 0.05). A higher rate of VCF hospitalization along with an increasing trend was noted in AS as compared to RA and compared to the general population. Better screening approaches and treatment strategies for AS patients with VCF risk are urgently needed to reduce hospitalizations and related complications. Key Points • An increasing trend of VCF hospitalization was noted in AS, in contrast to a declining trend in RA and a stable trend in the general population. • VCF in AS was associated with longer hospital stay and higher inpatient mortality than in RA and the general population.

Targeting angiogenesis for fracture nonunion treatment in inflammatory disease

Atrophic fracture nonunion poses a significant clinical problem with limited therapeutic interventions. In this study, we developed a unique nonunion model with high clinical relevance using serum transfer-induced rheumatoid arthritis (RA). Arthritic mice displayed fracture nonunion with the absence of fracture callus, diminished angiogenesis and fibrotic scar tissue formation leading to the failure of biomechanical properties, representing the major manifestations of atrophic nonunion in the clinic. Mechanistically, we demonstrated that the angiogenesis defect observed in RA mice was due to the downregulation of SPP1 and CXCL12 in chondrocytes, as evidenced by the restoration of angiogenesis upon SPP1 and CXCL12 treatment in vitro. In this regard, we developed a biodegradable scaffold loaded with SPP1 and CXCL12, which displayed a beneficial effect on angiogenesis and fracture repair in mice despite the presence of inflammation. Hence, these findings strongly suggest that the sustained release of SPP1 and CXCL12 represents an effective therapeutic approach to treat impaired angiogenesis and fracture nonunion under inflammatory conditions.

Chondrogenesis mediates progression of ankylosing spondylitis through heterotopic ossification

Ankylosing spondylitis (AS) is chronic inflammatory arthritis with a progressive fusion of axial joints. Anti-inflammatory treatments such as anti-TNF-α antibody therapy suppress inflammation but do not effectively halt the progression of spine fusion in AS patients. Here we report that the autoimmune inflammation of AS generates a microenvironment that promotes chondrogenesis in spine ligaments as the process of spine fusion. Chondrocyte differentiation was observed in the ligaments of patients with early-stage AS, and cartilage formation was followed by calcification. Moreover, a large number of giant osteoclasts were found in the inflammatory environment of ligaments and on bony surfaces of calcified cartilage. Resorption activity by these giant osteoclasts generated marrow with high levels of active TGF-β, which induced new bone formation in the ligaments. Notably, no Osterix+ osteoprogenitors were found in osteoclast resorption areas, indicating uncoupled bone resorption and formation. Even at the late and maturation stages, the uncoupled osteoclast resorption in bony interspinous ligament activates TGF-β to induce the progression of ossification in AS patients. Osteoclast resorption of calcified cartilage-initiated ossification in the progression of AS is a similar pathologic process of acquired heterotopic ossification (HO). Our finding of cartilage formation in the ligaments of AS patients revealed that the pathogenesis of spinal fusion is a process of HO and explained why anti-inflammatory treatments do not slow ankylosing once there is new bone formation in spinal soft tissues. Thus, inhibition of HO formation, such as osteoclast activity, cartilage formation, or TGF-β activity could be a potential therapy for AS.

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.

Semaphorin 4D Induces an Imbalance of Th17/Treg Cells by Activating the Aryl Hydrocarbon Receptor in Ankylosing Spondylitis

Objectives

Semaphorin 4D (Sema4D) is constitutively expressed on T cells and osteoclasts, and regulates T cell proliferation and bone remodeling. In addition, several studies have shown that Sema4D is involved in the pathogenesis of autoimmunity. We undertook this study to investigate the mechanism by which Sema4D affects the pathogenic progress of ankylosing spondylitis (AS).

Methods

Soluble Sema4D (sSema4D) levels in serum were analyzed by enzyme-linked immunosorbent assay. The cell surface levels and transcripts of Sema4D were evaluated in CD4 + and CD19 + cells from the AS patients and healthy individuals. The mRNA expression levels were assessed by quantitative polymerase chain reaction (qPCR). The proportions of Treg cells and IL-17-producing T-cells (Th17 cells) differentiated from CD4 + T cells were analyzed by flow cytometric analysis. The aryl hydrocarbon receptor (AhR) agonistic effect of Sema4D was detected by analyzing the activation of downstream signaling pathways and target genes using Luciferase and EROD assay.

Results

Levels of sSema4D were elevated in both serum from AS patients, and clinical features markers were correlated with serum sSema4D levels. Sema4D facilitated CD4 + T cells proliferation and Th17 cells differentiation and inhibited Treg cells differentiation by enhancing RORγt expression and reducing Foxp3 expression, with increasing expression and secretion of IL-17 and IL-22. It induced the expression and activity of AhR target gene CYP1A1 and XRE reporter activity via interaction with CD72.

Conclusion

These findings indicate that Sema4D as a potent activator of T cells in the immune response contributes to the inflammation of AS by inducing imbalance in Th17 and Treg cell populations in an AhR-dependent manner, suggesting it is a crucial participant in AS pathogenesis.

Biologic therapy and spinal radiographic progression in patients with axial spondyloarthritis: A structured literature review

We aimed to perform a structured literature review of spinal radiographic progression, as assessed by the modified Stoke Ankylosing Spondylitis Spine Score (mSASSS), in patients with ankylosing spondylitis (AS) or nonradiographic axial spondyloarthritis (nr-axSpA) treated with biologic therapy. Searches were limited to English language manuscripts published in the 11 years prior to 9 July 2019. Randomized controlled trials, open-label extensions (OLEs) and observational studies reporting mSASSS progression in patients with AS or nr-axSpA treated with biologics were eligible for inclusion. Bias was assessed using the methodological index for nonrandomized studies (MINORS) tool. Among the 322 studies identified in the literature search, 23 (11 OLEs and 12 cohort studies) met the eligibility criteria and were selected for inclusion. Most studies reported mSASSS progression in patients with AS receiving tumor necrosis factor inhibitor (TNFi) treatment. One study reported mSASSS progression in patients with AS treated with secukinumab, an interleukin-17A inhibitor. The mean (range) MINORS score was 11.3 (7-15) for the 15 noncomparative studies and 15 (12-22) for the 8 comparative studies. Although results of the individual studies were variable, mSASSS progression in patients with AS was generally minimal and slow with long-term TNFi therapy. Moreover, odds ratios for the likelihood of mSASSS progression with/without TNFi favoured TNFi therapy in several of the cohort studies. The rate of mSASSS progression following continuous secukinumab treatment was low and remained stable over 4 years. Of two studies reporting progression in patients with nr-axSpA treated with TNFis, one showed no mSASSS progression; however, the lack of control limited comparative conclusions.

The Risk and Consequences of Vertebral Fracture in Patients with Ankylosing Spondylitis: A Population-based Data Linkage Study

OBJECTIVE

To compare the long-term prevalence, incidence, and outcomes of vertebral fracture (VF) between ankylosing spondylitis (AS) patients and matched controls, including the role of extraarticular manifestations (EAM) and osteoporosis.

METHODS

This was a statewide observational study using linked health data for 2321 patients with AS and 22,976 controls presenting to hospital from 1980 to 2015. Data were analyzed using incidence rates (per 1000 person-yrs) and ratios (IRR), multivariable Cox proportional hazards regression, and Kaplan-Meier survival curves.

RESULTS

Over a median 13.92 (interquartile range 7.58-21.67) years of follow-up, patients with AS had a greater VF prevalence and greater incidence of developing a new VF compared to controls (9.3% vs 2.5%, 6.8% vs 1.9%, respectively, all P < 0.001). Patients with AS had an increased risk of developing a VF after adjustments for age, sex, and osteoporosis (HR 2.55, 95% CI 2.11-3.09) compared to controls; this risk remained throughout the study period. Patients with AS were 5 years younger at time of first VF (P = 0.008) and had a greater likelihood of a recurrent VF (IRR 4.64; 95% CI 4.54-4.75) compared to respective controls. Mortality overall was comparable between patients with AS and controls after adjustment for age, sex, osteoporosis, and VF status (HR 0.90; 95% CI 0.80-1.01).

CONCLUSION

The significantly increased risk of VF in patients with AS has not altered following the introduction of tumor necrosis factor inhibitor treatment. Although patients with AS experience a first VF at a younger age than controls, this does not lead to an increased risk of death.

Bone metabolic biomarkers and bone mineral density in male patients with early-stage Alzheimer's disease

PURPOSE

Alzheimer's disease (AD), osteoporosis, and osteopenia are the most common diseases in older individuals and share some similar pathophysiological processes of degeneration. The aim of this study is to investigate the association between bone metabolic biomarkers, bone mineral density (BMD), and early-stage AD in men.

METHODS

Forty-two male early-stage AD patients and 40 age-matched healthy older volunteers were enrolled. Serum calcium, osteocalcin, 1,25(OH)₂D₃, urine deoxypyridinoline/creatinine (DPD/Cr) ratio, urine calcium/creatinine (Ca/Cr) ratio, and BMD were measured. The correlation between early-stage AD and bone quality was evaluated.

RESULTS

The urine DPD/Cr, urine Ca/Cr, and serum osteocalcin levels in the early-stage AD patients were significantly higher than those in the healthy control (HC) group (P < 0.05). The BMD data showed that the cortical and total BMD at 38% of the tibial length in the early-stage AD patients were lower than those in the HC group (P < 0.05). Furthermore, there was a negative correlation between the Montreal Cognitive Assessment score and serum osteocalcin or urine DPD/Cr levels. Abnormal urine DPD/Cr, urine Ca/Cr, and cortical BMD levels were independent risk factors in male patients with early-stage AD.

CONCLUSION

Bone metabolic biomarkers and BMD are closely associated with early-stage AD in male patients. Our data indicated that the measurement of bone metabolic biomarkers and BMD may provide an alternative approach for screening AD patients at the early stage.

Osteoporosis in Rheumatic Diseases

Osteoporosis is a chronic disease characterized by an increased risk of fragility fracture. Patients affected by rheumatic diseases are at greater risk of developing osteoporosis. The purpose of the present review is to discuss the pathogenesis, epidemiology, and treatment of osteoporosis in patients affected by rheumatic diseases with special focus for rheumatoid arthritis, psoriatic arthritis, spondyloarthritis, systemic lupus erythematosus, systemic sclerosis, vasculitides, Sjogren syndrome, and crystal-induced arthritis.