Titer-Dependent Effect of Anti-Citrullinated Protein Antibodies On Systemic Bone Mass in Rheumatoid Arthritis Patients

A Clinical Evaluation of the Role of Autoimmunity in the Relation Between Erosions and Bone Mineral Density in Rheumatoid Arthritis

Background/objectives: Both erosions and osteoporosis in rheumatoid arthritis (RA) have common mechanisms. The aim of this study was to evaluate the relationship between erosion and bone mineral density (BMD) in RA and whether it can be driven by autoimmunity. Methods: Patients fulfilling the ACR 1987- or ACR/EULAR 2010-criteriae for RA. performed radiographs (erosions evaluated by the modified Sharp/van der Heidje erosion score) and biology for anti-citrullinated peptide antibodies (ACPAs), rheumatoid factors (RFs) and anti-nuclear antibodies (ANAs) at intervals of less than 2 years from dual-energy X-ray absorptiometry (DXA) for BMD assessment. Results: A total of 149 patients were included, (75.8% women, mean age of 62 y.o (SD 9.61) and a median disease duration of 132 months [60; 240]). A total of 61.1% patients were ACPA positive, 79.9% were erosive and 10.7% had a hip or spine T-score ≤ -2.5. A higher erosion score was associated with a lower BMD (value: -0.222; p = 0.009) and T-score (value -0.397; p < 0.0001) in the hip. ACPA status was associated with a higher erosion score (63.0 (53.2) vs. 45.5 (44.1) for ACPA- (p = 0.04)). ACPA titers were associated with a lower BMD in the hip (value -0.216; p = 0.01). In linear regression, erosion and BMD were still associated, but this association is not driven by ACPA status or titer. Conclusions: In RA patients, erosions and BMD are inversely associated but this relationship does not seem to be driven by autoimmunity only. However, the presence of ACPA or erosion should lead to osteoporosis screening.

Autoantibodies Serum Level and 10-Year Risk of Fractures Evaluated by FRAX® Tool in Rheumatoid Arthritis Patients

Purpose

FRAX® is a tool used for evaluation of risk of fracture in RA and non-RA patients and to identify those eligible for intervention. One of the limitations of FRAX in RA settings is that it does not consider factors known to contribute to osteoporosis such as autoantibodies. This study analysed the association of anti-mutated citrullinated vimentin antibody (anti-MCV), anti-cyclic citrullinated peptide antibody (anti-CCP), IgM rheumatoid factor (RF), IgA RF with 10-year risk of major osteoporosis and hip fracture.

Methods

FRAX® tool was used to estimate 10-year risk of major osteoporosis fracture and hip fracture in 189 RA patients over 40 years of age. Anti-MCV, anti-CCP, IgM RF and IgA RF were tested using enzyme immunoassay and analysed at different levels. Results were adjusted for various confounders including disease activity.

Results

Fifty-one (26.9%) RA patients had high (≥20%) 10-year risk of major osteoporosis fracture and 67 (35.4%) had high (>3%) 10-year risk of hip fracture. Among all the tested autoantibodies, only IgM RF at elevated levels was associated with high 10-year risk of major osteoporosis fracture (adjusted OR = 4.1, 95% CI = 1.5-11.3, p = 0.006) and of hip fracture (adjusted OR = 17.4, 95% CI = 3.7-81.3, p < 0.0001). There was no agreement between FRAX and femoral neck (FN) BMD. None of the autoantibodies tested were associated with FN osteopenia or osteoporosis including IgM RF at high levels.

Conclusion

Our study highlights the importance of quantitative measurement of autoantibodies in assessment of risk for fractures among RA patients. Our preliminary findings need to be assessed in prospective studies to determine the actual predictive value of high IgM RF levels among patients with RA.

Comorbidity of patients with noncommunicable diseases in general practice. Eurasian guidelines

Создание руководства поддержано Советом по терапевтическим наукам отделения клинической медицины Российской академии наук.

Prognostic nutritional index as an indicator for the development of bone fragility fracture in patients with rheumatoid arthritis

OBJECTIVES

The validity of prognostic nutritional index (PNI) as an index of incident bone fragility fracture (inc-BFF) in rheumatoid arthritis (RA) patients was investigated.

METHODS

RA patients whom continuously followed up for >3 years were picked up. Patients were classified in accordance with inc-BFF positivity (BFF+ and BFF-). Their clinical background including PNI was statistically examined for inc-BFF. The background factors were compared between the two groups. Patients were narrowed into subgroups according to the factor that showed a significant difference between the two groups, and they were statistically examined according to the PNI for the inc-BFF. The two groups were narrowed with propensity score matching and compared to the PNI.

RESULTS

A total of 278 patients with 44 BFF+ and 234 BFF- were recruited. In the background factors, the presence of prevalent BFF and the simplified disease activity index remission rate had a significantly higher risk ratio. In a subgroup who comorbid lifestyle-related diseases, PNI had a significantly higher risk ratio for the inc-BFF. After the propensity score matching, the PNI showed no significant difference between the two groups.

CONCLUSIONS

PNI is available when patients with RA comorbid lifestyle-related diseases. PNI is not an independent key for the inc-BFF in RA patients.

Regulation of differentiation and generation of osteoclasts in rheumatoid arthritis

INTRODUCTION

Rheumatoid arthritis (RA), which affects nearly 1% of the world's population, is a debilitating autoimmune disease. Bone erosion caused by periarticular osteopenia and synovial pannus formation is the most destructive pathological changes of RA, also leads to joint deformity and loss of function,and ultimately affects the quality of life of patients. Osteoclasts (OCs) are the only known bone resorption cells and their abnormal differentiation and production play an important role in the occurrence and development of RA bone destruction; this remains the main culprit behind RA.

METHOD

Based on the latest published literature and research progress at home and abroad, this paper reviews the abnormal regulation mechanism of OC generation and differentiation in RA and the possible targeted therapy.

RESULT

OC-mediated bone destruction is achieved through the regulation of a variety of cytokines and cell-to-cell interactions, including gene transcription, epigenetics and environmental factors. At present, most methods for the treatment of RA are based on the regulation of inflammation, the inhibition of bone injury and joint deformities remains unexplored.

DISCUSSION

This article will review the mechanism of abnormal differentiation of OC in RA, and summarise the current treatment oftargeting cytokines in the process of OC generation and differentiation to reduce bone destruction in patients with RA, which isexpected to become a valuable treatment choice to inhibit bone destruction in RA.

Risk factors for osteoporosis and fractures in rheumatoid arthritis

People with rheumatoid arthritis (RA) have both disease-specific risk factors for osteoporosis and fractures in addition to those that affect the general population. Disease specific risks include directly pathogenic auto-antibodies, chronic exposure to systemic inflammation, and joint damage causing early disability. Risk factors that affect the general population which may have a higher prevalence in RA include smoking, calcium and vitamin D deficiency as well as hypogonadism. Additionally, chronic exposure to glucocorticoids results in reduced bone mineral density and body composition changes which can further increase fracture risk. In this review we discuss these risk-factors for osteoporosis as well as factors that may impact fall and fracture risk in people with RA.

The Impact of Seropositivity on Systemic Bone Loss in Rheumatoid Arthritis-A 3-Year Interim Analysis of a Longitudinal Observational Cohort Study

Objective

To explore the impact of seropositivity on systemic bone loss in rheumatoid arthritis (RA).

Methods

We conducted an interim analysis of the RA registry. Patients were examined with dual-energy X-ray absorptiometry at baseline and again 3 years later. Participants were grouped into seropositive (SPRA) and seronegative (SNRA) based on the presence or absence of rheumatoid factor (RF) and/or anti-cyclic citrullinated peptide antibodies (ACPA). After matching (1:2) for age and sex, SNRA and SPRA patients were divided into groups A and B. Each matched group (A or B) was further subdivided according to the number of antibodies present (0, group I; 1, group II; 2, group III). Multiple ordinary least squares regression was used with the dependent variables to develop a model to predict bone mineral density (BMD) change.

Results

A total of 477 participants who completed a 3-year observation period were included. After matching, 312 participants were enrolled (group A, 104; group B, 208). Three years later, group B had significant BMD reduction in the femoral neck (FN) (p < 0.001), total hip (TH) (p = 0.001), and first through fourth lumbar vertebrae (L1–4) (p = 0.006), while group A had bone loss only at FN (p = 0.002). Groups I, II, and III included 104, 52, and 156 participants, respectively. Compared to baseline, BMD decreased significantly at FN (p = 0.002) in group I, FN (p < 0.001) in group II, and FN (p < 0.001), TH (p = 0.002), and L1–4 (p = 0.016) in group III. In terms of regression-adjusted percent change in BMD, more significantly negative changes were found at all measured sites in group B (p < 0.001, all) and at TH and L1–4 within groups I-III (p for trend < 0.001 and < 0.001, respectively). Regardless of antibodies, anti-osteoporotic therapy can preserve bone density in RA patients.

Conclusion

After 3 years, SPRA patients lost more bone density than SNRA patients. More attention should be paid to SPRA patients, especially those with double-positive antibodies, including a vigorous evaluation of BMD and fracture risk. Anti-osteoporotic therapy can prevent BMD loss irrespective of autoantibodies.

Effect of sarcopenia and poor balance on vertebral spinal osteoporotic fracture in female rheumatoid arthritis

This study investigated the effect of poor balance and sarcopenia on vertebral spinal osteoporotic fracture (VOPF) in female rheumatoid arthritic (RA) patients. A total of 195 female RA and 126 normal subjects were enrolled, and the correlations between sarcopenia, poor balance and VOPF were analyzed. Furthermore, we explored the relationships between sarcopenia or poor balance with disease related indexes of female RA. Binary logistic regression analyses were performed to identify potential risk factors for VOPF in female RA. We found that female RA had an increased risk of sarcopenia, poor balance (Berg balance scale, BBS ≤ 40) and VOPF than controls (P < 0.0001). Female RA with VOPF were more likely to have poor balance and sarcopenia than those without VOPF (P < 0.0001-0.05). Meanwhile, female RA with sarcopenia and poor balance often had higher disease activity, more serious joint damage and worse joint function (P < 0.05) compared with those without sarcopenia and poor balance. Binary logistic regression analysis (LR backwald) revealed that age (OR = 1.112, 95% CI 1.065-1.160, P < 0.0001), OP (OR = 10.137, 95% CI 4.224-24.330, P < 0.0001) and GCs usage (OR = 3.532, 95% CI 1.427-8.741, P = 0.006) were risk factors, while SMI (OR = 0.386, 95% CI 0.243-0.614, P < 0.0001) and BBS (OR = 0.952, 95% CI 0.929-0.976, P < 0.0001) were protective factors for VOPF in female RA. Hence, sarcopenia and poor balance are associated with a higher risk for VOPF and are closely related to disease activity and joint structure damage of female RA.

Abnormalities of Peripheral Lymphocyte Subsets in Rheumatoid Arthritis Patients Complicated with Osteoporosis

Introduction

Osteoporosis (OP) is one of the major comorbidities of rheumatoid arthritis (RA). Recent studies have shown that immune cells modulate bone health and regulate bone remodeling. However, the alterations of lymphocyte subsets in RA patients with OP are unclear. Here, we assessed the absolute numbers and proportions of the subsets in RA sufferers with OP and investigated the clinical significance.

Methods

A total of 777 RA patients and 117 gender- and age-matched healthy controls (HCs) were enrolled in this study. Patients were divided into RA-non-OP and RA-OP group according to their bone mineral density (BMD) and the history of fragility fracture. Peripheral lymphocyte subsets of participants were assessed by flow cytometry.

Results

Among 220 (28.31%) RA-OP patients, there were higher levels of erythrocyte sedimentation rate (ESR) (P = 0.011), C-reactive protein (CRP) (P = 0.028), rheumatoid factor (RF) (P = 0.013) and anti-cyclic citrullinated peptide antibody (ACPA) (P = 0.010), while red blood cells (RBC) (P = 0.039) were lower than those in RA-non-OP group. Compared with those of HCs and RA-non-OP group, the level of circulating Th17 cells in RA-OP patients was significantly increased (P < 0.05), while those of Tregs decreased (P < 0.01), leading to a higher ratio of Th17/Treg (P < 0.01). Notably, the level of B cells in both RA-non-OP and RA-OP group was reduced, this alteration was more obvious in patients with OP (P < 0.05).

Conclusions

Immune disorders characterized by peripheral Th17/Treg imbalance and reduced B cells may contribute directly or indirectly to OP in RA, and this deserves more clinical attention.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40744-022-00452-x.

Secondary Osteoporosis

Osteoporosis is a global public health problem, with fractures contributing to significant morbidity and mortality. Although postmenopausal osteoporosis is most common, up to 30% of postmenopausal women, > 50% of premenopausal women, and between 50% and 80% of men have secondary osteoporosis. Exclusion of secondary causes is important, as treatment of such patients often commences by treating the underlying condition. These are varied but often neglected, ranging from endocrine to chronic inflammatory and genetic conditions. General screening is recommended for all patients with osteoporosis, with advanced investigations reserved for premenopausal women and men aged < 50 years, for older patients in whom classical risk factors for osteoporosis are absent, and for all patients with the lowest bone mass (Z-score ≤ -2). The response of secondary osteoporosis to conventional anti-osteoporosis therapy may be inadequate if the underlying condition is unrecognized and untreated. Bone densitometry, using dual-energy x-ray absorptiometry, may underestimate fracture risk in some chronic diseases, including glucocorticoid-induced osteoporosis, type 2 diabetes, and obesity, and may overestimate fracture risk in others (eg, Turner syndrome). FRAX and trabecular bone score may provide additional information regarding fracture risk in secondary osteoporosis, but their use is limited to adults aged ≥ 40 years and ≥ 50 years, respectively. In addition, FRAX requires adjustment in some chronic conditions, such as glucocorticoid use, type 2 diabetes, and HIV. In most conditions, evidence for antiresorptive or anabolic therapy is limited to increases in bone mass. Current osteoporosis management guidelines also neglect secondary osteoporosis and these existing evidence gaps are discussed.

Regulation of bone mass in inflammatory diseases

Inflammation is among the major determinants of bone loss in chronic disease and aging. Bone metabolism is radically affected by inflammation with consequent bone loss and increased fracture risk. Various cytokines and mediators are involved in the pathogenesis of bone loss in inflammatory conditions. The present review has the aim of discussing the main pathways involved in the pathogenesis of bone loss in inflammatory diseases, focusing in particular on the Wnt system and its regulators. Literature review of studies published between inception to 2021 on osteoporosis and inflammation was conducted. I will discuss the epidemiology of osteoporosis and fractures in common inflammatory diseases. The molecular basis of bone loss related to inflammation will be discussed as well. Finally, the effects of various anti-inflammatory medications on bone metabolism will be reviewed.

A CD40 variant is associated with systemic bone loss among patients with rheumatoid arthritis

OBJECTIVES

Little is known about genes predisposing to systemic bone loss (SBL) in rheumatoid arthritis (RA). Therefore, we examined the association between SBL and variants of genes playing a critical role in both immune response and bone homeostasis among patients with RA.

METHODS

IRAK-1 rs3027898, IRAK-2 rs3844283, IRAK-2 rs708035, IFIH1 rs1990760, CD40 rs48104850, TNFAIP3 rs2230926, and miR146-a rs2910164 were genotyped in 176 adult RA patients. Bone mineral density (BMD) was measured using dual-energy X-ray absorptiometry (DXA).

RESULTS

Low BMD was observed in 116 (65.9%) patients. Among them, 60 (34.1%) had low femoral neck (FN) Z score, 72 (40.9%) had low total femur (TF) Z score, and 105 (59.6%) had low lumbar spine (LS) Z score. Among all the SNPs assessed, only CD40 rs4810485 was found to be associated with reduced TF Z score with the CD40 rs4810485 T allele protecting against reduced TF Z score (OR = 0.40, 95% CI = 0.23-0.68, p = 0.0005). This association was confirmed in the multivariate logistic regression analysis (OR = 0.31, 95% CI = 0.16-0.59, p = 3.84 × 10^-4). Moreover, median FN BMD was reduced among RA patients with CD40 rs4810485 GG genotype compared to RA patients harbouring CD40 rs4810485 TT and GT genotypes (0.788 ± 0.136 versus 0.826 ± 0.146 g/cm², p = 0.001). IRAK-1 rs3027898, IRAK-2 rs3844283, rs708035, IFIH rs1990760, TNFAIP3 rs2230926, and miR146-a rs2910164 were not found to be associated with SBL.

CONCLUSION

This study for the first time ever demonstrated an association between a CD40 genetic variant and SBL among patients with RA.

KEY POINTS

• CD40 rs4810485 GG genotype is associated with decreased BMD among patients with RA. • CD40 rs4810485 might serve as a genetic marker for SBL in RA. • CD40 genetic variations might be integrated in future development of more effective therapeutic interventions for prevention of SBL in RA.

Mapping Knowledge Structure and Themes Trends of Osteoporosis in Rheumatoid Arthritis: A Bibliometric Analysis

Background: Rheumatoid arthritis is a chronic disabling disease characterized by chronic inflammation, articular cartilage destruction, and reduced bone mass. Multiple studies have revealed that the development of osteoporosis in rheumatoid arthritis (RA; ORA) patients could be led to a reduced quality of life and increased healthcare costs. Nevertheless, no attempt has been made to analyze the field of ORA research with the bibliometric method. This study aimed to provide a comprehensive overview of the knowledge structure and theme trends in the field of ORA research from a bibliometric perspective.

Methods: Articles and reviews regarding ORA from 1998 to 2021 were identified from the Web of Science database. An online bibliometric platform, CiteSpace, and VOSviewer software were used to generate visualization knowledge maps including co-authorship, co-citation, and co-occurrence analysis. SPSS, R, and Microsoft Excel software were used to conduct curve fitting and correlation analysis, and to analyze quantitative indicators, such as publication and citation counts, h-index, and journal citation reports.

Results: A total of 1,081 papers with 28,473 citations were identified. Publications were mainly concentrated in North America, Western Europe, and Eastern Asia. Economic strength is an important factor affecting scientific output. The United States contributed the most publications (213) with the highest h-index value (46) as of September 14, 2021. Diakonhjemmet Hospital and professor Haugeberg G were the most prolific institution and influential authors, respectively. Journal of Rheumatology was the most productive journal concerning ORA research. According to the burst references, “anti-citrullinated protein antibodies” and “preventing joint destruction” have been recognized as the hot research issues in the domain. The keywords co-occurrence analysis identified “teriparatide,” “interleukin-6,” “Wnt,” and “vertebral fractures” as the important future research directions.

Conclusion: This was the first bibliometric study comprehensively summarizing the trends and development of ORA research. Our findings could offer practical sources for scholars to understand the key information in this field, and identify the potential research frontiers and hot directions in the near future.

A Comparison of Demographics, Disease Activity, Disability, and Treatment Among Rheumatoid Arthritis Patients with and without Osteoporosis

Introduction

Osteoporosis (OP) is one of the most common comorbidities associated with rheumatoid arthritis (RA). Literatures reported that the risk for developing OP was strongly associated with duration and severity of RA. We aim to elaborate on the consequences of OP on disease activity and management plan in patients with RA.

Patients and Methods

A retrospective cohort study recruited 408 patients, including those with RA alone and with RA plus OP. The RA disease activity in the patients was assessed using disease activity score in 28 joints (DAS28-CRP). A statistical analysis was performed to compare data between the two groups of patients and determine any significant risk factor associated with the development of OP in RA patients.

Results

Of 408 patients who were included in this study, 353 patients (86.5%) had only RA, while 55 patients (13.5%) had RA with OP and showed significant difference (P = 0.04) concerning age categories. Patients diagnosed with RA and OP had RA duration longer than RA-only patients (independent t-test, P = 0.01). The two groups had almost similar disease activity at the three clinical visits, as well, had nearly similar disability at their first visit, whereas RA with OP patients had significant greater disability at their 2^nd and 3^rd visits (independent t-test, P = 0.001). Both groups were treated with the same biologic and non-biologic medication of similar frequency, although RA patients with OP received steroid more frequently than patients had RA only (61.7% vs. 41.7%, chi square test, P = 0.03).

Conclusion

There was no significant difference in disease activity at both groups of patients. However, RA with OP group had longer duration of RA, were more frequently treated with steroids, and had greater disability. We recommend physicians focus on controlling RA disease activity, early screening for and treating of OP.

IgA rheumatoid factor is associated with bone mineral density preservation in rheumatoid arthritis

INTRODUCTION

Autoantibodies such as IgM rheumatoid factor (RF) and anti-citrullinated proteins/peptides antibodies (ACPA) have previously been incriminated in systemic bone loss in rheumatoid arthritis (RA). There are, however, no data describing association of IgA RF and IgG RF with systemic bone loss.

OBJECTIVE

This study was aimed to investigate the association of RF isotypes with systemic bone loss among patients with RA.

METHODS

RF isotypes and ACPA were measured by enzyme-linked immunosorbent assay among 153 patients with RA. Bone mineral density (BMD) was assessed using dual-energy X-ray absorptiometry.

RESULTS

Ninety-four (61.4%) patients had positive IgA RF, 89 (58.2%) had positive IgG RF, 109 (71.2%) had positive IgM RF, whereas 122 (80.3%) RA patients tested positive for ACPA. Compared to the IgA RF-negative patients, IgA RF-positive patients exhibited higher disease activity and had higher RF titers. Seven (4.6%) patients had low BMD at femoral neck, 12 (7.8%) at total femur, and 47 (30.7%) at lumbar spine. IgA RF was found to be associated with protection against low BMD at spine (OR = 0.47, 95% CI = 0.23-0.95, p = 0.034). This association was further confirmed in the multivariate regression analysis taking into account several potential confounding factors (OR = 0.21, 95% CI = 0.06-0.65, p = 0.039). No association between low BMD and the presence of IgG RF or IgM RF or ACPA was found.

CONCLUSION

IgA RF for the first time ever was shown to be associated with BMD preservation at spine in RA. Key points • IgA RF was associated with protection against low spinal BMD. • No association between low BMD and the presence of IgG RF or IgM RF was found.

IgA Immune Complexes Induce Osteoclast-Mediated Bone Resorption

Objective

Autoantibodies are detected in most patients with rheumatoid arthritis (RA) and can be of the IgM, IgG or IgA subclass. Correlations between IgA autoantibodies and more severe disease activity have been previously reported, but the functional role of IgA autoantibodies in the pathogenesis of RA is ill understood. In this study, we explored the effect of IgA immune complexes on osteoclast mediated bone resorption.

Methods

Anti-citrullinated peptide antibody (ACPA) and anti-carbamylated protein (anti-CarP) antibody levels of the IgA and IgG isotype and rheumatoid factor (RF) IgA were determined in synovial fluid (SF) of RA patients. Monocytes, neutrophils, and osteoclasts were stimulated with precipitated immune complexes from SF of RA patients or IgA- and IgG-coated beads. Activation was determined by neutrophil extracellular trap (NET) release, cytokine secretion, and bone resorption.

Results

NET formation by neutrophils was enhanced by SF immune complexes compared to immune complexes from healthy or RA serum. Monocytes stimulated with isolated SF immune complexes released IL-6 and IL-8, which correlated with the levels of ACPA IgA levels in SF. Osteoclasts cultured in the presence of supernatant of IgA-activated monocytes resorbed significantly more bone compared to osteoclasts that were cultured in supernatant of IgG-activated monocytes (p=0.0233). Osteoclasts expressed the Fc receptor for IgA (FcαRI; CD89) and Fc gamma receptors. IgA-activated osteoclasts however produced significantly increased levels of IL-6 (p<0.0001) and IL-8 (p=0.0007) compared to IgG-activated osteoclasts. Both IL-6 (p=0.03) and IL-8 (p=0.0054) significantly enhanced bone resorption by osteoclasts.

Conclusion

IgA autoantibodies induce release of IL-6 and IL-8 by immune cells as well as osteoclasts, which enhances bone resorption by osteoclasts. We anticipate that this will result in more severe disease activity in RA patients. Targeting IgA-FcαRI interactions therefore represents a promising novel therapeutic strategy for RA patients with IgA autoantibodies.

Anti-carbamylated protein antibodies in premenopausal rheumatoid arthritis women: relation to disease activity and bone loss

OBJECTIVES

Anti-carbamylated protein antibodies (anti-CarP Abs) are present in patients with RA, however, their association with bone loss is not confirmed. The purpose of this study was to determine the relation between the serum level of anti-CarP Abs in premenopausal RA women and disease activity and bone loss.

METHODS

This case-control study was conducted on 48 premenopausal women with RA and 48 matched healthy premenopausal women. All RA women were subjected to clinical examination, disease activity assessment using the 28-joint DAS (DAS28) and Clinical Disease Activity Index (CDAI), functional assessment using the HAQ, physical activity assessment using the International Physical Activity Questionnaire (IPAQ), fatigue assessment using the Modified Fatigue Impact Scale (MFIS), serological tests as well as anti-CarP Abs using ELISA. Moreover, the BMD was measured by DXA and plain X-ray of both hands was done to assess juxta-articular osteopenia and erosions.

RESULTS

The anti-CarP Abs level was significantly higher in RA patients than in healthy controls. The serum level of anti-CarP Abs had a significant positive correlation with the RA DAS28, CDAI, HAQ, MFIS and original Sharp score, while a significant negative correlation was present with the IPAQ. Anti-CarP Abs were negatively correlated with either spine BMD or Z-score and positively correlated with the original Sharp score.

CONCLUSION

Anti-CarP Abs were higher in premenopausal RA women compared with older and BMI matched healthy women. Anti-CarP Abs are associated with higher RA disease activity, increased disability and fatigability and decreased physical activity. Moreover, anti-CarP Abs are associated with systemic trabecular bone loss as well as local bone loss.

Impact of Anti-Citrullinated Protein Antibodies on Progressive Systemic Bone Mineral Density Loss in Patients With Early Rheumatoid Arthritis After Two Years of Treat-to-Target

Objectives

To investigate the association of anti-citrullinated protein antibodies (ACPA) with changes in systemic bone mineral density (BMD) in patients with early rheumatoid arthritis (RA) after two years of treat-to-target.

Methods

BMD was measured at the lumbar spine (LS) and femoral neck (FN) in 100 patients with recent onset RA at baseline and after 24 months of treatment aimed at low disease activity (LDA) according to the 28-joints disease activity score (DAS28 <3.2). Multivariable regression analyses were performed to determine independent associations between autoantibodies and other disease and treatment-related parameters with BMD loss.

Results

After 24 months, the majority of the patients were at least in LDA (78%), with slightly more ACPA-positive subjects achieving the target. The BMD had significantly decreased at both the LS (mean [SD] percent loss -1.8 [6.2], p=0.03) and the FN (-2.4 [7.3], p=0.03) in ACPA-positive but not in ACPA-negative patients. Consequently, the proportion of patients with reduced BMD (Z score ≤-1) after 24 months was significantly higher among ACPA-positive patients at both the spine (39.5% vs 19.3%, p=0.05) and the hip (37.2% vs 12.2%, p=0.007). The association between ACPA and BMD loss was independent of other variables including age, gender, disease activity, cumulative dose of glucocorticoids and duration of therapy with bisphosphonates at the LS but not the FN.

Conclusions

ACPA are associated with ongoing BMD loss at the spine despite suppression of inflammation and adoption of prophylactic measures. ACPA-positive RA patients should be therefore strictly monitored for the development of osteoporosis.

Autoantibodies in Rheumatoid Arthritis - Laboratory and Clinical Perspectives

Measurement of two groups of autoantibodies, rheumatoid factor (RF) and anti-citrullinated protein/peptide antibodies (ACPA) have gained increasing significance in the diagnosis and classification of rheumatoid arthritis (RA) over the last 65 years. Despite this rising importance of autoimmune serology in RA, there is a palpable lack of harmonization between different commercial RF and ACPA tests. While a minimal diagnostic specificity has been defined for RF tests, which almost always are related to an international reference preparation, neither of this applies to ACPA. Especially assays with low diagnostic specificity are associated with very low positive predictive values or post-test probabilities in real world settings. In this review we focus on issues of practical bearing for the clinical physician diagnosing patients who potentially have RA, or treating patients diagnosed with RA. We advocate that all clinically used assays for RF and ACPA should be aligned to a common diagnostic specificity of 98-99% compared to healthy controls. This high and rather narrow interval corresponds to the diagnostic specificity seen for many commercial ACPA tests, and represents a specificity that is higher than what is customary for most RF assays. Data on antibody occurrence harmonized in this way should be accompanied by test result-specific likelihood ratios for the target diagnosis RA on an ordinal or interval scale, which will provide the clinical physician with more granular and richer information than merely relating numerical values to a single cut-off point. As many physicians today are used to evaluate autoantibodies as positive or negative on a nominal scale, the introduction of test result-specific likelihood ratios will require a change in clinical mindset. We also discuss the use of autoantibodies to prognosticate future arthritis development in at-risk patients as well as predict severe disease course and outcome of pharmacological treatment.

Association Between Bone Mineral Density and Autoantibodies in Patients With Rheumatoid Arthritis

Objective

Autoantibodies, such as anti–citrullinated protein antibodies (ACPAs), have been described as inducing bone loss in rheumatoid arthritis (RA), which can also be reflected by bone mineral density (BMD). We therefore examined the association between osteoporosis and autoantibodies in two independent RA cohorts.

Methods

Dual x‐ray absorptiometry (DXA) of the lumbar spine and left hip was performed in 408 Dutch patients with early RA during 5 years of follow‐up and in 198 Swedish patients with early RA during 10 years of follow‐up. The longitudinal effect of ACPAs and other autoantibodies on several BMD measures was assessed using generalized estimating equations.

Results

In the Dutch cohort, significantly lower BMD at baseline was observed in ACPA‐positive patients compared to ACPA‐negative patients, with an estimated marginal mean BMD in the left hip of 0.92 g/cm² (95% confidence interval [95% CI] 0.91–0.93) versus 0.95 g/cm² (95% CI 0.93–0.97) (P = 0.01). In line with this, significantly lower Z scores at baseline were noted in the ACPA‐positive group compared to the ACPA‐negative group (estimated marginal mean Z score in the left hip of 0.18 [95% CI 0.08–0.29] versus 0.48 [95% CI 0.33–0.63]) (P < 0.01). However, despite clear differences at baseline, ACPA positivity was not associated with greater decrease in absolute BMD or Z scores over time. Furthermore, there was no association between BMD and higher levels of ACPAs or other autoantibodies (rheumatoid factor and anti–carbamylated protein antibodies). In the Swedish cohort, ACPA‐positive patients tended to have a higher prevalence of osteopenia at baseline (P = 0.04), but again, ACPA positivity was not associated with an increased prevalence of osteopenia or osteoporosis over time.

Conclusion

The presence of ACPAs is associated with significantly lower BMD at baseline, but not with greater BMD loss over time in treated RA patients. These results suggest that ACPAs alone do not appear to contribute to bone loss after disease onset when disease activity is well‐managed.

Osteoporosis and fractures in rheumatoid arthritis

PURPOSE OF REVIEW

Rheumatoid arthritis (RA) is associated with increased risk for osteoporotic fracture. We highlight RA-specific risk factors for bone mineral density (BMD) loss and fractures and considerations regarding the diagnosis and treatment of osteoporosis in patients with RA.

RECENT FINDINGS

Anticitrullinated protein antibody (ACPA) positivity, although associated with low BMD in early RA, is not associated with accelerated BMD loss over time when compared to ACPA negative individuals. Studies have found reduced BMD in individuals on low doses of glucocorticoids (GCs). Poor functional status and frailty are additional important risk factors for low BMD and fractures. Heightened fracture risk in RA may be mitigated by tight disease control, and biologic therapies are associated with more stable BMD compared to nonbiologic therapies. Evidence-based guidelines specific for treating osteoporosis in patients with RA do not exist. Thus, treatment decisions are based on general osteoporosis guidelines, taking into account additional RA-specific risk factors.

SUMMARY

Recent studies have advanced knowledge of RA-specific risk factors for BMD loss and fractures. Future studies applying these findings to modify established fracture risk algorithms as well as evaluating osteoporosis treatments in RA cohorts are needed to reduce the risk of disabling fractures in these patients.

Establishment and verification of an osteoporosis risk model in patients with rheumatoid arthritis: a valuable new model

To establish a model for osteoporosis risk in patients with rheumatoid arthritis and validate the model. A newly generated predictive model has been suggested to have good differentiation, calibration, and clinical validity and may be a useful clinical model for predicting osteoporosis in patients with rheumatoid arthritis.

PURPOSE

To establish a prediction model for osteoporosis risk in patients with rheumatoid arthritis and validate the model internally and externally.

METHODS

A total of 270 patients with rheumatoid arthritis who underwent bone mineral density measurement at our hospital from June 2019 to June 2020 were enrolled in the study. The patients were divided into two groups according to their entry time: a training set containing the first 2/3 of the patients (n = 180) and a validation set containing the remaining 1/3 of the patients (n = 90). Binary logistic regression analysis was used to establish the regression models, and the concordance index (C-index), calibration plot, and decision curve analysis were used to evaluate the prediction model.

RESULTS

Five variables, including age (X1), course of disease (X2), the disease activity score using 28 joint counts (DAS28) (X4), anti-cyclic citrullinated peptide antibody (CCP) (X7), and 7-joint ultrasonic bone erosion (X14), were selected to enter the model. The prediction model is Logit Y = - 12.647 + 0.133X1 + 0.011X2 + 0.754X4 + 0.001X7 + 0.605X14. The model had good differentiation; the C-index in the internal verification was 0.947 (95% CI is 0.932-0.977) and the C-index in the external verification was 0.946 (95% CI is 0.940-0.994). The calibration plot of the model showed excellent consistency between the prediction probability and actual probability. When > 0.483 was taken as the cutoff value for the diagnosis of osteoporosis, the sensitivity, specificity, positive likelihood ratio, negative likelihood ratio, and Jordan index of the model were 90.24%, 87.76%, 7.37, 0.11, and 78.00%, respectively.

CONCLUSION

A newly generated predictive model has been suggested to have good differentiation, calibration, and clinical validity and may be a useful clinical model for predicting osteoporosis in patients with rheumatoid arthritis.

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.

Bone phenotypes in rheumatology - there is more to bone than just bone

Osteoarthritis, rheumatoid arthritis, psoriatic arthritis, and ankylosing spondylitis, all have one clear common denominator; an altered turnover of bone. However, this may be more complex than a simple change in bone matrix and mineral turnover. While these diseases share a common tissue axis, their manifestations in the area of pathology are highly diverse, ranging from sclerosis to erosion of bone in different regions. The management of these diseases will benefit from a deeper understanding of the local versus systemic effects, the relation to the equilibrium of the bone balance (i.e., bone formation versus bone resorption), and the physiological and pathophysiological phenotypes of the cells involved (e.g., osteoblasts, osteoclasts, osteocytes and chondrocytes). For example, the process of endochondral bone formation in chondrocytes occurs exists during skeletal development and healthy conditions, but also in pathological conditions. This review focuses on the complex molecular and cellular taxonomy of bone in the context of rheumatological diseases that alter bone matrix composition and maintenance, giving rise to different bone turnover phenotypes, and how biomarkers (biochemical markers) can be applied to potentially describe specific bone phenotypic tissue profiles.

Osteoporosis in patients with rheumatoid arthritis: an update in epidemiology, pathogenesis, and fracture prevention

INTRODUCTION

Rheumatoid arthritis (RA) is a chronic disabling disease characterized by a symmetrical articular involvement due to ongoing joint inflammation, if left insufficiently treated. Local and generalized bone loss is one of the main extra-articular complications of RA and leads to an increased risk for fragility fractures, which further impair functional ability, quality of life, and life expectancy. Therefore, there is an urgent need for good fracture risk management in the vulnerable RA patient.

AREAS COVERED

The authors review: the epidemiology and pathophysiology (i.e. risk factors) of osteoporosis (OP), fracture, and vertebral fracture risk assessment, the effects of anti-rheumatic drugs on bone loss, pharmacological treatment of OP in RA including both bisphosphonates (BP) and newer drugs including anti-resorptives and osteoanabolic treatment options.

EXPERT OPINION

Patients with active RA have elevated bone resorption and local bone loss. Moreover, these patients are at increased risk for generalized bone loss, vertebral and non-vertebral fractures. Since general risk factors (such as low BMI, fall risk) and RA-related factors play a role, optimal fracture prevention in RA patients is based on optimal diagnostics based on both of these factors, and on the use of adequate non-medical and medical treatment options.

Pharmacological Management of Osteoporosis in Rheumatoid Arthritis Patients: A Review of the Literature and Practical Guide

Rheumatoid arthritis (RA) is a chronic disabling disease that is associated with increased localized and generalized osteoporosis (OP). Previous studies estimated that approximately one-third of the RA population experience bone loss. Moreover, RA patients suffer from a doubled fracture incidence depending on several clinical factors, such as disease severity, age, glucocorticoid (GC) use, and immobility. As OP fractures are related to impaired quality of life and increased mortality rates, OP has an enormous impact on global health status. Therefore, there is an urgent need for a holistic approach in daily clinical practice. In other words, both OP- and RA-related factors should be taken into account in treatment guidelines for OP in RA. First, to determine the actual fracture risk, dual-energy X-ray absorptiometry (DXA), including vertebral fracture assessment (VFA) and calculation of the 10-year fracture risk with FRAX^®, should be performed. In case of high fracture risk, calcium and vitamin D should be supplemented alongside anti-osteoporotic treatment. Importantly, RA treatment should be optimal, aiming at low disease activity or remission. Moreover, GC treatment should be at the lowest possible dose. In this way, good fracture risk management will lead to fracture risk reduction in RA patients. This review provides a practical guide for clinicians regarding pharmacological treatment options in RA patients with OP, taking into account both osteoporotic-related factors and factors related to RA.

The Impact of Cigarette Smoking on Risk of Rheumatoid Arthritis: A Narrative Review

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation and subsequent proliferation of synovial tissues, which eventually leads to cartilage and bone destruction without effective treatments. Anti-citrullinated cyclic peptide/protein antibody (ACPA) and rheumatoid factor (RF) are two main characteristic autoantibodies found in RA patients and are associated with unfavorable disease outcomes. Although etiologies and causes of the disease have not been fully clarified yet, it is likely that interactive contributions of genetic and environmental factors play a main role in RA pathology. Previous works have demonstrated several genetic and environmental factors as risks of RA development and/or autoantibody productions. Among these, cigarette smoking and HLA-DRB1 are the well-established environmental and genetic risks, respectively. In this narrative review, we provide a recent update on genetic contributions to RA and the environmental risks of RA with a special focus on cigarette smoking and its impacts on RA pathology. We also describe gene–environmental interaction in RA pathogenesis with an emphasis on cigarette smoking and HLA-DRB1.

Osteoimmunology in rheumatoid and psoriatic arthritis: potential effects of tofacitinib on bone involvement

Chronic inflammation, such as that present in rheumatoid arthritis (RA) and psoriatic arthritis (PsA), leads to aberrations in bone remodeling, which is mediated by several signaling pathways, including the Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway. In this light, pro-inflammatory cytokines are now clearly implicated in these processes as they can perturb normal bone remodeling through their action on osteoclasts and osteoblasts at both intra- and extra-articular skeletal sites. As a selective inhibitor of JAK1 and JAK3, tofacitinib has the potential to play a role in the management of rheumatic diseases such as RA and PsA. Preclinical studies have demonstrated that tofacitinib can inhibit disturbed osteoclastogenesis in RA, which suggests that targeting the JAK-STAT pathway may help limit bone erosion. Evidence from clinical trials with tofacitinib in RA and PsA is encouraging, as tofacitinib treatment has been shown to decrease articular bone erosion. In this review, the authors summarize current knowledge on the relationship between the immune system and the skeleton before examining the involvement of JAK-STAT signaling in bone homeostasis as well as the available preclinical and clinical evidence on the benefits of tofacitinib on prevention of bone involvement in RA and PsA.Key Points• Chronic inflammation in rheumatoid arthritis (RA) and psoriatic arthritis (PsA) leads to disturbances in bone remodeling• Bone remodeling is mediated by several signaling pathways, including the JAK-STAT pathway• Tofacitinib, a selective inhibitor of JAK1 and JAK3, is active in RA and PsA and may help limit systemic bone loss through inhibiting disturbed osteoclastogenesis• Clinical trials show that tofacitinib reduces articular bone erosion.

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.

Shared epitope defines distinct associations of cigarette smoking with levels of anticitrullinated protein antibody and rheumatoid factor

OBJECTS

Although the association of cigarette smoking (CS) with susceptibility to rheumatoid arthritis (RA) has been established, the impact of CS on anticitrullinated cyclic peptide/protein antibody (ACPA) and rheumatoid factor (RF) levels in RA has yet been clear, especially in relation to shared epitope (SE) alleles.

METHODS

A total of 6239 subjects, the largest Asian study ever, from two independent Japanese cohorts were enrolled. Precise smoking histories, levels of ACPA and RF, and HLA-DRB1 allele status were withdrawn from databases. Associations between CS and high ACPA or RF levels, defined by the top quartiles, were evaluated. The effect of HLA-DRB1 alleles on the association was further investigated.

RESULTS

CS at RA onset conferred the risks of high levels of both antibodies, especially RF (OR 2.06, p=7.4×10^-14; ACPA, OR 1.29, p=0.012), suggesting that RF level is more sensitive to CS than ACPA level. The patients who had quitted CS before RA onset showed a trend of decreased risks of developing high levels of ACPA or RF, and the risks steadily decreased according to the cessation years. The association of CS with high ACPA level was observed only in subjects carrying SE alleles, while the association of high RF level was observed regardless of SE.

CONCLUSIONS

CS confers the risks of high autoantibody levels in RA in different manners; CS interacts with SE alleles on ACPA level, while CS impacts on RF level despite SE allele. These data suggest novel distinct production mechanisms of RF and ACPA.

How Autoantibodies Regulate Osteoclast Induced Bone Loss in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease, characterized by autoimmunity that triggers joint inflammation and tissue destruction. Traditional concepts of RA pathogenesis have strongly been focused on inflammation. However, more recent evidence suggests that autoimmunity per se modulates the disease and in particular bone destruction during the course of RA. RA-associated bone loss is caused by increased osteoclast differentiation and activity leading to rapid bone resorption. Autoimmunity in RA is based on autoantibodies such as rheumatoid factor (RF) and autoantibodies against citrullinated proteins (ACPA). These autoantibodies exert effector functions on immune cells and on bone resorbing osteoclasts, thereby facilitating bone loss. This review summarizes potential pathways involved in increased destruction of bone tissue in RA, particularly focusing on the direct and indirect actions of autoantibodies on osteoclast generation and function.

Relationship between bone mineral density and anti-citrullinated protein antibody and rheumatoid factor in patients with rheumatoid arthritis

Objective

Rheumatoid arthritis (RA) is one of the causes of osteoporosis, and it leads to systemic bone loss. The anti-citrullinated protein antibody (ACPA) and rheumatoid factor (RF) are associated with local and systemic low bone mineral density and osteoclast-mediated bone resorption independently of inflammation in patients with RA. In this article, we aimed to evaluate the relationship between the ACPA, RF, and systemic bone mineral density in patients with RA.

Methods

Ninety-three patients (6 male, 87 female) with RA were included in the study. The disease activity score 28-erythrocyte sedimentation rate and titers of RF, ACPA, and bone mineral density of the total hip, femoral neck, and lumbar areas were evaluated. The independent samples t-test, Mann-Whitney U-test, Spearman’s correlation, and multivariable regression analysis were used for the statistical analysis.

Results

The RF and ACPA were positive in 40.9% and 48.4% of patients with RA, respectively. Disease activity was negatively correlated with the T- and Z-scores. The T- and Z-scores were lower in the seropositive group than in the seronegative group. The ACPA was negatively correlated with the T- and Z-scores of the femoral neck. There was a significant difference for the Z-score of the femoral neck in patients with ACPA and RF-positive patients compared to seronegative patients with RA.

Conclusion

A low bone mineral density, especially in the femoral neck, is associated with the presence of ACPA and RF. It would be a more appropriate approach to carefully monitor osteoporosis in seropositive RA patients.

Anti-citrullinated protein antibodies are associated with osteopenia but not with pain at diagnosis of rheumatoid arthritis: data from the BARFOT cohort

BACKGROUND

Anti-citrullinated protein antibodies (ACPA) have been suggested to have a potential role in both bone loss and pain in rheumatoid arthritis (RA), based on studies in vitro and in animal models. Here we addressed if anti-cyclic citrullinated (anti-CCP) antibodies were associated with osteopenia or pain in patients with RA, at the time for diagnosis.

METHODS

Baseline data from the BARFOT (Better Anti-Rheumatic PharmacOTherapy) cohort, which consists of patients with RA with a disease duration of 1 year or less, were analyzed. To be included, they should have been assessed by anti-CCP, dual-energy X-ray absorptiometry (DEXA) of lumbar spine and hip, and/or digital X-ray radiogrammetry (DXR) of the metacarpal bones. Osteopenia was defined as a z-score < - 1 SD. Pain VAS > 40 mm, was defined as patient unacceptable pain. Multiple logistic regression analyses were performed to assess whether anti-CCP was independently associated with osteopenia or unacceptable pain.

RESULTS

Of the 657 patients, 65% were women, 58% were anti-CCP positive, 37% had osteopenia in the lumbar spine, and 29% had osteopenia in the hip. Sixty-one percent had unacceptable pain at diagnosis. Patients positive for anti-CCP had significantly more frequently osteopenia in the femoral neck and Ward's triangle compared with anti-CCP-negative patients (p = 0.016 and 0.003, respectively). This difference was found in men at any anti-CCP titer, but in women, osteopenia in these hip locations was found only in those with high anti-CCP titers (> 500 IU/ml). Anti-CCP was not associated with osteopenia in the lumbar spine or the metacarpal bones. In multiple logistic regression analyses, anti-CCP was independently associated with osteopenia in the femoral neck and/or Ward's triangle but not with unacceptable pain. Instead, inflammatory variables were independently associated with unacceptable pain.

CONCLUSION

These data show that in patients with early RA, anti-CCP positivity was independently associated with osteopenia in the femoral neck and/or Ward, but not in the lumbar spine. In our patients, we could not confirm a recently suggested association between anti-CCP antibodies and pain. Further studies are necessary to explore the possible clinical relevance of interactions between ACPA, bone, and pain found in vitro and in animal models.

Association of high titers of anti-carbamylated protein antibodies with decreased bone mineral density in early arthritis patients

Rheumatoid arthritis (RA) has a negative impact on bone that is partly mediated by anti-citrullinated proteins antibodies (ACPA). These antibodies are associated with erosions, and with juxta-articular and systemic bone loss. Other RA autoantibodies, the anti-carbamylated protein antibodies (anti-CarPA), are independently associated with erosions. However, we do not know if they are also associated with juxta-articular and systemic bone loss. Here, we have addressed this question with data from 548 early arthritis (EA) patients. Bone mineral density (BMD) was assessed by dual-energy x-ray absorptiometry at the lumbar spine (LS), total hip (TH) and metacarpophalangeal joints (MCP). The 25.9% anti-CarPA positive patients did not show significant differences in BMD Z-scores with the negative patients. Nevertheless, this result was due to the similarity between negative and low-positive (below the median of the positive) patients, whereas the high-positive patients showed significant decrease of BMD at LS (β = -0.39, p = 0.01) and TH (β = -0.30, p = 0.02); but not at the juxta-articular bone of MCP. Given the overlap between anti-CarPA and ACPA, we included the two autoantibodies in an analysis that showed significantly lower BMD Z-scores at LS and TH (p< 0.01) only in the ACPA positive/anti-CarPA high-positive subgroup. However, the similar coefficients of regression between the ACPA positive/anti-CarPA high-positive and the ACPA negative/anti-CarPA high-positive subgroups (β = -0.50 vs. -0.52 at LS, and β = -0.37 vs. -0.30 at TH) suggested an independent association. Overall, these results support a contribution of anti-CarPA to systemic bone loss in EA patients.

Detection of IgM-rheumatoid factor and anti-citrullinated protein antibodies in healthy horses and their comparison

Rheumatoid factor (RF) is used in human and veterinary medicine in the form of IgM RF traditionally to support the diagnosis of rheumatoid arthritis (RA). In the latest diagnostic criteria, presence of anti - citrullinated protein antibodies (ACPA) was added to the grading system for the diagnosis of RA in humans. A change which is not integrated or routinely used in veterinary medicine. The criteria changed partly because of RF's diagnostic shortcomings, which include its increased titer detection in humans with non-rheumatoid diseases, inability to predict the disease and increased titers over the limit in the older population. Clinical signs similar to human RA were reported in horses in a condition known as idiopathic polysynovitis. Similarities in the clinical presentation to RA raised a question to the usability of RF and ACPA in horses. In our study, sixty clinically healthy horses, ranging from 3 days to 30 years of age, were evaluated for their serum levels of IgM RF. 55 of these horses were tested for ACPA, using methods of ELISA measuring Anti - CFG (Anti citrullinated fibrinogen antibody). The results of the study demonstrated the existence of an age-dependent increase in the level of IgM RF up to the age of about 9 years and ACPA's independence of the horse's age as well as both markers independence of the horse sex.

Association of High Anti-Cyclic Citrullinated Peptide Seropositivity and Lean Mass Index With Low Bone Mineral Density in Rheumatoid Arthritis

OBJECTIVE

Osteoporotic fractures are associated with high morbidity and mortality. Persons with rheumatoid arthritis (RA) have twice the risk of osteoporosis-related fracture than age-matched controls, the causes for which remain unknown. We investigated contributions of RA characteristics, medication use, and body composition to low bone mineral density (BMD) in patients with RA.

METHODS

Data were from the Arthritis, Body Composition, and Disability Study (n = 138; 82 women, 56 men). Demographic, clinical, laboratory, and functional variables were collected at study visits. Body composition (fat, lean muscle, and BMD) was measured by dual x-ray absorptiometry. Linear regression analyses evaluated the association between predictors and femoral neck BMD.

RESULTS

Average disease duration was 19 years, 70% of patients were rheumatoid factor positive, and 55% were high-positive anti-cyclic citrullinated peptide (anti-CCP). Age and high anti-CCP positivity were negatively associated with BMD after controlling for other variables (β = -0.003 and -0.055, respectively, P < 0.05). Appendicular lean mass index (ALMI) was positively associated with BMD (β = 0.053, P < 0.0001). In high anti-CCP positivity participants, increasing anti-CCP levels were associated with a negative linear trend in BMD (β = -0.011, P = 0.026).

CONCLUSION

High anti-CCP positivity and ALMI were strongly associated with BMD in patients with RA. The linear relationship of anti-CCP levels with lower BMD supports the hypothesis that processes specific to RA negatively impact BMD. In contrast, ALMI was positively associated with BMD, emphasizing the importance of this potentially modifiable risk factor. Our findings highlight the complicated interplay of RA disease-specific and functional factors and their impact on bone mass.

The Role of Autoantibodies in Bone Metabolism and Bone Loss

Many autoimmune diseases are associated with deranged bone metabolism. The resulting localized or systemic bone loss can compromise the quality of life of patients by causing local bone deformities or fragility fractures. There is emerging evidence that antibodies have a direct impact on key players of bone homeostasis, in particular osteoclasts. Clinical and pre-clinical studies provide insight into the function of autoantibodies related to Rheumatoid Arthritis (rheumatoid factor, anti-citrullinated protein antibodies, and anti-carbamylated protein antibodies) and their inflammation-independent interaction with bone cells. Furthermore, we summarize the current knowledge about neutralizing antibodies to the antiresorptive protein osteoprotegerin, which have been described in patients with Coeliac Disease, Rheumatoid Arthritis, and Spondyloarthritis.

A Cross-Sectional Study of the Association between Autoantibodies and Qualitative Ultrasound Index of Bone in an Elderly Sample without Clinical Autoimmune Disease

Bone loss is characteristic of the ageing process and a common complication of many autoimmune diseases. Research has highlighted a potential role of autoantibodies in pathologic bone loss. The confounding effects of immunomodulatory drugs make it difficult to establish the contribution of autoantibodies amongst autoimmune disease sufferers. We attempted to examine the relationship between autoantibodies and bone mass in a population of 2812 elderly participants without clinical autoimmune disease. Serum samples were assayed for a panel of autoantibodies (anti-nuclear, extractable nuclear antigen, anti-neutrophil cytoplasmic, thyroid peroxidase, tissue transglutaminase, anti-cardiolipin, rheumatoid factor, and cyclic citrullinated peptide). Bone mass was measured using quantitative ultrasound (QUS) of the calcaneus. The relationship between each autoantibody and bone mass was determined using linear regression models. Anti-nuclear autoantibodies were the most prevalent, positive in approximately 11%, and borderline in roughly 23% of our sample. They were also the only autoantibody observed to be significantly associated with QUS index in the univariate analysis (n = 1628; r = -0.20; 95% CI: -0.40-0.00; p = 0.046). However, statistical significance was lost after adjustment for various other potential confounders. None of the other autoantibodies was associated with QUS index in either univariate or multivariate analysis. We are limited by the cross-sectional nature of the study and the low prevalence of autoantibodies in our nonclinical sample.

Association of Low Bone Mineral Density with Anti-Citrullinated Protein Antibody Positivity and Disease Activity in Established Rheumatoid Arthritis: Findings from a US Observational Cohort

Introduction

To assess the relationship between low bone mineral density (BMD), anti-cyclic citrullinated peptide-2 (anti-CCP2) antibodies, and disease activity in patients with established rheumatoid arthritis (RA).

Methods

Patients enrolled in a single-center, observational cohort registry of patients with RA. Eligible patients had known BMD, as measured by digital X-ray radiogrammetry (DXR–BMD), and anti-CCP2 antibody measurements at the same time point or within 6 months. Anti-CCP2–immunoglobulin (Ig)G-positive (+) patients (≥ 20 U/mL) were distributed into three equal groups (Gp1–3), representing increasing anti-CCP2 antibody concentrations. Associations between BMD and anti-CCP2 antibody status and titer were explored in multivariate regression analyses controlling for covariates (including age, duration of RA, use of steroids, use of osteoporosis medication). Association between disease activity (DAS28 [CRP] < 2.6) and bone loss was also explored.

Results

A total of 149 patients (all women) were included (47 anti-CCP2 antibody negative [−], 102 anti-CCP2+ [34\titer group]). Mean disease duration was greater in the three anti-CCP2+ groups vs. the anti-CCP2− group. DXR–BMD was lower in the anti-CCP2+ vs. the anti-CCP2− groups (Gp1–3 vs. anti-CCP2−: P < 0.0001 for left and right hands). DXR–BMD decreased with increasing anti-CCP2 titer (P < 0.001 for left and right hands). Patients with low DXR–BMD were less likely to have a DAS28 (CRP) < 2.6 (P = 0.0181).

Conclusion

Among patients with established RA, data suggest that anti-CCP2+ patients, particularly those with high anti-CCP2 antibody titers, have lower hand BMD, and patients with lower hand BMD are less likely to have low disease activity.

Funding

Bristol-Myers Squibb.

Trial Registration

Clinicaltrials.gov identifier, NCT01793103.

Electronic supplementary material

The online version of this article (10.1007/s12325-017-0657-x) contains supplementary material, which is available to authorized users.

Anti-CCP-positive patients with RA have a higher 10-year probability of fracture evaluated by FRAX®: a registry study of RA with osteoporosis/fracture

Background

Positive anticyclic citrullinated peptide (anti-CCP+) is associated with bone loss in patients with rheumatoid arthritis (RA). However, whether overall positivity or specific levels of anti-CCP are associated with prevalent fracture or a 10-year probability of fracture remains unclear.

Methods

This interim analysis of an RA registry was conducted at Chang Gung Memorial Hospital in Kaohsiung (CGMHK) for RA-related osteoporosis/fracture. Consecutive patients with RA who had visited the rheumatology clinic at CGMHK since September 1, 2014, and fulfilled the classification criteria of RA were enrolled. The demographics, disease duration, Disease activity in 28 joints based on erythrocyte sedimentation rate (DAS28-ESR), lifestyle, evidence of previous fracture, risk factors of fracture in the Fracture Risk Assessment Tool (FRAX®), and FRAX® score of each participant were collected. Anti-CCP, rheumatoid factor (RF), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and bone mineral density (BMD) were measured at enrollment. The patients were grouped by positivity or quartiles of anti-CCP level (I–IV).

Results

Five hundred twenty-one patients with RA were enrolled through May 31, 2016. In total, 359 (68.9%) patients were anti-CCP+. Compared with anti-CCP− patients, anti-CCP+ patients had a significantly higher DAS28-ESR (p = 0.0001) and 10-year probability of major (15.0 [18.9] vs. 12.0 [15.3], p = 0.0461) or hip (5.0 [9.2] vs. 3.6 [8.2], p = 0.0118) fracture, but a significantly lower BMD of the FN (p = 0.0196). The rates of osteoporosis and previous fracture were comparable. There were 130, 127, 132, and 132 patients in groups I–IV, respectively. The DAS28-ESR was significantly different (p = 0.0001) among the groups and correlated to anti-CCP levels. The BMD and 10-year probability of major (p = 0.0067) and hip (p = 0.0013) fracture among the groups were also different.

Conclusions

Anti-CCP+ RA patients had a higher 10-year probability of major or hip fracture, independent of anti-CCP levels, and a lower BMD of the FN than anti-CCP− patients.

Is osteoporosis an autoimmune mediated disorder?

The last two decades have marked a growing understanding of the interaction occurring between bone and immune cells. The chronic inflammation and immune system dysfunction commonly observed to occur during the ageing process and as part of a range of other pathological conditions, commonly associated with osteoporosis has led to the recognition of these processes as important determinants of bone disease. This is further supported by the recognition that the immune and bone systems in fact share regulatory mechanisms and progenitor molecules. Research into this complex synergy has provided a better understanding of the immunopathogenesis underlying bone diseases such as osteoporosis. However, existing research has largely focussed on delineating the role played by inflammation in pathogenic bone destruction, despite increasing evidence implicating autoantibodies as important drivers of osteoporosis. This review shall attempt to provide a comprehensive overview of existing research examining the role played by autoantibodies in osteoporosis in order to determine the potential for further research in this area. Autoantibodies represent promising targets for the improved treatment and diagnosis of inflammatory bone loss.

Tocilizumab potentially prevents bone loss in patients with anticitrullinated protein antibody-positive rheumatoid arthritis

Rheumatoid arthritis (RA) is associated with a high risk of osteoporosis and fracture. Interleukin (IL)-6 inhibitors may suppress osteoclast activation. Anticitrullinated protein antibody (ACPA) titers are inversely associated with bone mineral density (BMD). However, the differential effect of ACPA on bone turnover marker (BTM) and BMD changes after IL-6 inhibition remains unclear. This prospective study recruited patients with active RA with inadequate response to methotrexate or biologics. BMD was measured before and after 2-year tocilizumab (TCZ) treatment. Serum osteocalcin, N-terminal propeptide of type I collagen (P1NP), and C-terminal cross-linking telopeptide of type I collagen (CTX) levels were assessed at the baseline and after treatment. We enrolled 76 patients with RA (89.5% women, age: 57.2 ± 13.3 years) receiving TCZ. The 28-joint disease activity score was negatively correlated with BMD and T-scores of the lumbar spine and bilateral femoral neck. ACPA-positive patients had lower lumbar spine and femoral neck T-scores. After 2-year TCZ treatment, CTX levels significantly decreased (0.32 ± 0.21 vs. 0.26 ± 0.17, p = 0.038). Femoral neck BMD increased significantly (0.71 ± 0.22 vs. 0.69 ± 0.55, p = 0.008). Decreased CTX levels and improved BMD were observed only in ACPA-positive patients. After treatment, femoral neck BMD significantly increased only in patients receiving a glucocorticoid dose of ≥5 mg/day. Two-year TCZ treatment reduced bone resorption and increased femoral BMD in ACPA-positive patients. The net effects of glucocorticoids and IL-6 inhibition on BMD imply that strict inflammation control might affect bone metabolism.

Decrease in bone mineral density during three months after diagnosis of early rheumatoid arthritis measured by digital X-ray radiogrammetry predicts radiographic joint damage after one year

Background

Periarticular osteopenia is an early sign of incipient joint injury in rheumatoid arthritis (RA), but cannot be accurately quantified using conventional radiography. Digital X-ray radiogrammetry (DXR) is a computerized technique to estimate bone mineral density (BMD) from hand radiographs. The aim of this study was to evaluate whether decrease in BMD of the hands (BMD loss), as determined by DXR 3 months after diagnosis, predicts radiographic joint damage after 1 and 2 years in patients with early RA.

Methods

Patients (n = 176) with early RA (<12 months after onset of symptoms) from three different Swedish rheumatology centers were consecutively included in the study, and 167 of these patients were included in the analysis. Medication was given in accordance with Swedish guidelines, and the patients were followed for 2 years. Rheumatoid factor and antibodies to cyclic citrullinated peptides (anti-CCP) were measured at baseline, and 28-joint Disease Activity Score (DAS28) was assessed at each visit. Radiographs of the hands and feet were obtained at baseline, 3 months (hands only) and 1 and 2 years. Baseline and 1-year and 2-year radiographs were evaluated by the Larsen score. Radiographic progression was defined as a difference in Larsen score above the smallest detectable change. DXR-BMD was measured at baseline and after 3 months. BMD loss was defined as moderate when the decrease in BMD was between 0.25 and 2.5 mg/cm²/month and as severe when the decrease was greater than 2.5 mg/cm²/month. Multivariate regression was applied to test the association between DXR-BMD loss and radiographic damage, including adjustments for possible confounders.

Results

DXR-BMD loss during the initial 3 months occurred in 59% of the patients (44% moderate, 15% severe): 32 patients (19%) had radiographic progression at 1 year and 45 (35%) at 2 years. In multiple regression analyses, the magnitude of DXR-BMD loss was significantly associated with increase in Larsen score between baseline and 1 year (p = 0.033, adjusted R-squared = 0.069).

Conclusion

DXR-BMD loss during the initial 3 months independently predicted radiographic joint damage at 1 year in patients with early RA. Thus, DXR-BMD may be a useful tool to detect ongoing joint damage and thereby to improve individualization of therapy in early RA.