Changes of serum levels of MMP-3, sRANKL, and OPG in juvenile-onset ankylosing spondylitis patients carrying different HLA-B27 subtypes

Serum levels of interleukin-34 and RANKL as multivariable predictors of bone erosion seen by ultrasonography in patients with ankylosing spondylitis

Background

Ankylosing spondylitis (AS) is a chronic inflammatory arthritic disease, and sacroiliitis, enthesitis, and propensity for sacroiliac and spinal fusion are characteristic pathological features. Interleukin-34 (IL-34) plays a role in the induction and differentiation of osteoclasts. Other inflammatory factors are not directly involved in the induction and differentiation, but play an indirect role by modulating the level of receptor activator of nuclear factor-κB (RANKL) and other molecules during the process of inflammatory bone destruction in AS. However, to our knowledge, the relationship between enthesitis and bone erosion, and IL-34 and RANKL in AS has not yet been elucidated.

Objective

To determine the correlation between serum IL-34, RANKL, and disease severity including enthesitis and bone erosion in patients with AS and develop multivariable predictive model.

Methods

We conducted a cross-sectional study of 40 patients with AS, compared with 40 patients with osteoarthritis, and 40 healthy volunteers. Their serum levels of IL-34 and RANKL were measured using enzyme-linked immunosorbent assays (ELISAs). Enthesitis and bone erosion were assessed with real-time ultrasonography. Spearman rank correlation coefficients were determined to analyze the relationship between the variables. Multiple logistic regression was used to determine associations and receiver operating characteristic (ROC) curve analyses were conducted to determine the diagnostic performance of cytokine levels.

Results

In patients with AS, serum levels of IL-34 (878.9 ± 116.4 pg/mL) and RANKL (155.6 ± 13.8 pg/mL) were significantly (P < 0.01) higher than those in patients with osteoarthritis (626.6 ± 79.0 and 138.1 ± 15.3 pg/mL, respectively) or a healthy group (612.9 ± 61.1 and 104.9 ± 15.4 pg/mL, respectively). Serum levels of IL-34 were not significantly correlated with the levels of RANKL. In patients with AS, serum levels of IL-34 and RANKL adjusted for age and weight were significantly correlated with enthesitis (0.798, P < 0.01; 0.347, P < 0.05, respectively) and bone erosion (0.822, P < 0.01; 0.368, P < 0.05, respectively). The area under the ROC curve (AUC) for the serum levels of IL-34 was 0.995 between patients with AS and healthy individuals. When serum level of IL-34 was >697.1 pg/mL, the sensitivity (SE) was >99% and specificity (SP) was 95.0%. The AUC for IL-34 was 0.982 between patients with AS and patients with osteoarthritis. When serum IL-34 was >688.4 pg/mL, the SE was >99% and SP 85.0%. IL-34 correlation with the number of bone erosions of enthesis was rs = 0.795, P < 0.01. The AUC for serum RANKL was 0.993 between patients with AS and healthy individuals. When serum RANKL was >126.2 pg/mL, the SE was 97.5% and SP 97.5%. The AUC for serum RANKL was 0.798 between patients with AS and patients with osteoarthritis. When serum RANKL was >149.3 pg/mL, the SE was 70% and SP was 80.0%.

Conclusions

In patients with AS, serum levels of IL-34 and RANKL may be useful indicators of enthesitis, especially for bone erosions. IL-34 is associated with AS-associated enthesis damage and is a potential biomarker for predicting subsequent progression in patients with AS.

Bone mineral density, bone metabolism-related factors, and microRNA-218 are correlated with disease activities in Chinese ankylosing spondylitis patients

Objective

To investigate bone mineral density (BMD), bone metabolism‐related factors, and microRNA‐218 in Chinese ankylosing spondylitis (AS) patients and to identify their correlation with disease activities and the treatment with TNF‐α inhibitors.

Methods

A total of 89 AS patients were enrolled in the study. Patients’ information and laboratory examination results were collected. BMD of the anteroposterior lumbar spine (L2‐L4), left femoral neck, and whole body were measured and T‐scores were calculated. MicroRNA‐218 was extracted from PBMCs of AS patients and detected by RT‐PCR. Bone metabolism‐related factors were detected using protein chips and flow cytometer.

Results

Out of 86 patients undergoing whole‐body BMD measurement, 14 had osteopenia and 72 had normal BMD without osteoporosis or high BMD. Compared with short‐ (disease duration ≤3 years) and long‐term groups (disease duration ≥10 years), medium‐term group (disease duration ranges from 3 to 10 years) showed lowest BMD. Patients with onset age ≤20 years old had significantly lower BMD than the other groups (p < 0.05). The BMD of femoral neck had negative correlation with CRP (p < 0.05) and no correlation with BASDAI or ESR. Both whole‐body BMD and femoral neck BMD were negatively correlated with BASMI (p < 0.05). Dickkopf‐1 (DKK‐1), platelet‐derived growth factor‐BB (PDGF‐BB), and receptor activator of NF‐κB ligand (RANKL)/osteoprotegerin (OPG) were significantly increased, while Osteopontin (OPN) was significantly decreased in AS patients. Expression of microRNA‐218 in PBMC of AS patients was low and was positively correlated with BASMI (p < 0.05), but it was not correlated with the duration of disease, age of onset, BASDAI, ESR, or BMD.

Conclusion

Loss of bone mass mainly occurred at the inflammatory sites in AS patients, depending on the severity of inflammation. The alleviation of inflammation can improve loss of bone mass and bone metabolism disorders. Anti‐inflammatory treatment is critical for the treatment of secondary osteoporosis caused by AS.

Serum RANKL levels in Chinese patients with ankylosing spondylitis: a meta-analysis

Objective

We aimed to determine the association between serum receptor activator of nuclear factor-kappa B ligand (sRANKL) levels and ankylosing spondylitis (AS) in Chinese patients.

Methods

The PubMed, Cochrane Library, Embase, Chinese Biomedical Database, Web of Science, China National Knowledge Infrastructure, VIP, and Wan Fang databases were searched for studies conducted before October 1, 2020, without language restrictions. STATA version 12.0 and Revman version 5.3 were used to analyze the data. The standard mean differences (SMDs) and corresponding 95% confidence intervals (95% CIs) were calculated.

Results

Twelve clinical case–control studies, including 585 patients with AS and 423 healthy controls, were included. The combined SMD for sRANKL suggested that the sRANKL level was significantly higher in Chinese patients with AS than in healthy controls (SMD: 3.27, 95% CI 2.11–4.43, P < 0.00001). Serum RANKL-related factor osteoprotegerin (OPG) levels (SMD: 0.86, 95% CI 0.09–1.64, P < 0.03) were lower in the Chinese patients with AS than in healthy controls, and the RANKL/OPG ratio (SMD = 1.05, 95% CI 0.64–1.46, P < 0.00001) in Chinese patients with AS was approximately the same as that of healthy controls. Subgroup analysis indicated that patients from North and South China had higher sRANKL levels than controls; the sRANKL levels of patients from South China were higher in the subgroup with a Bath Ankylosing Spondylitis Functional Index (BASFI) of > 4 than those of patients in other subgroups. In terms of duration, patients with AS for > 8 years had higher sRANKL levels than health controls. Other subgroup analyses were conducted by region, language, source of control, age, and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI). In these subgroups, the sRANKL levels were significantly higher in the patients with AS than in healthy controls. The BASFI and BASDAI were sources of heterogeneity.

Conclusions

The sRANKL levels are higher in Chinese patients with AS, especially among those from South China. sRANKL levels may be positively correlated with the pathogenesis of AS among Chinese patients.

MALT-1 inhibition attenuates the inflammatory response of ankylosing spondylitis by targeting NF-κB activation

BACKGROUND

The present study aimed to investigate the effects of mucosa-associated lymphoid tissue lymphoma translocation protein (MALT)-1 on ankylosing spondylitis and its underlying mechanisms.

METHODS

Proteoglycan induced ankylosing spondylitis (PGIA) mouse model was established and the expression patterns of MALT-1 were determined in joint tissue. Next, the mice were intraarticularly administrated with MALT-1 in the PGIA mouse model. Meanwhile, shRNA was intraarticularly administrated to PGIA mice. The incidence of arthritis and clinical score was evaluated. Besides, the levels of inflammatory cytokines and matrix metalloproteinases (MMPs) were measured. Protein expressions of full-length CYLD (FL-CYLD), C-terminal cleavage fragment (CYLD-CL), and nuclear factor (NF)-κB were determined.

RESULTS

The mRNA and protein levels of MALT1 were increased in the PGIA mouse model. The treatment of MALT-1 accelerated arthritis incidence and joint damage, whereas shMALT-1 suppressed arthritis symptoms in the PGIA mouse model. In addition, treatment of shMALT-1 suppressed the levels of inflammatory cytokines (tumor necrosis factor (TNF)-α, interleukin (IL)-6, and IL-1β), MMP-3, and MMP-9. Furthermore, the treatment of shMALT-1 suppressed the levels of CYLD and NF-κB in the joint tissues in the PGIA mouse model.

CONCLUSION

The inhibition of MALT-1 suppressed the inflammatory response in ankylosing spondylitis in part by the regulation of CYLD and NF-κB.

MicroRNA let-7i-3p affects osteoblast differentiation in ankylosing spondylitis via targeting PDK1

Ankylosing spondylitis (AS) is a chronic autoimmune disease in which let-7i has been studied to involved. But, whether let-7i-3p could regulate osteoblast differentiation in AS remains unclear. This research targeted to decipher the impact of let-7i-3p on AS progression by modulating pyruvate dehydrogenase kinase 1 (PDK1). The bone mineral density of femur and lumbar vertebra and the maximum loading and bending elastic modulus of tibia, tumor necrosis factor-α (TNF-α), matrix metalloproteinase (MMP)-3, osteoprotegerin (OPG) and receptor activator of nuclear factor-κB ligand (RANKL) in serum of AS mice, the pathological condition of synovial tissue were determined via let-7i-3p inhibitor and OE-PDK1 in animal experiment. Also, the cell viability and ALP activity were measured by let-7i-3p inhibitor and OE-PDK1 in cell experiments. let-7i-3p and PDK1 expression were detected. Let-7i-3p raised and PDK1 declined in AS mice. Depleted let-7i-3p and restored PDK1 increased bone mineral density and maximum loading and bending elastic modulus of tibia, reduced TNF-α, MMP-3 and RANKL contents, attenuated the pathological condition of synovial tissue and raised OPG content in AS mice. In cell experiments, up-regulating PDK1 and down-regulating let-7i-3p enhanced cell viability and ALP activity in AS mice. Low expression of let-7i-3p could enhance osteoblast differentiation in AS by up-regulating PDK1.Abbreviations: AS: Ankylosing spondylitis; PDK1: pyruvate dehydrogenase kinase 1; TNF-α: tumor necrosis factor-α MMP: matrix metalloproteinase; OPG: osteoprotegerin; RANKL: receptor activator of nuclear factor-κB ligand; miRNAs: MicroRNAs; BMD: bone mineral density; PFA: paraformaldehyde; NC: negative control; OE: overexpression; HE: Hematoxylin-eosin; PBS: phosphate-buffered saline; EDTA: ethylene diamine tetraacetic acid; DMEM: Dulbecco's Modified Eagle Medium; RT-qPCR: Reverse transcription quantitative polymerase chain reaction; GAPDH: glyceraldehyde phosphate dehydrogenase; UTR: untranslated region; WT: wild type; MUT: mutant type.

Novel approaches to develop biomarkers predicting treatment responses to TNF-blockers

Introduction: Chronic inflammatory diseases (CIDs) cause significant morbidity and are a considerable burden for the patients in terms of pain, impaired function, and diminished quality of life. Important progress in CID treatment has been obtained with biological therapies, such as tumor-necrosis-factor blockers. However, more than a third of the patients fail to respond to these inhibitors and are exposed to the side effects of treatment, without the benefits. Therefore, there is a strong interest in developing tools to predict response of patients to biologics. Areas covered: The authors searched PubMed for recent studies on biomarkers for disease assessment and prediction of therapeutic responses, focusing on the effect of TNF blockers on immune responses in spondyloarthritis (SpA), and other CID, in particular rheumatoid arthritis and inflammatory bowel disease. Conclusions will be drawn about the possible development of predictive biomarkers for response to treatment. Expert opinion: No validated biomarker is currently available to predict treatment response in CID. New insight could be generated through the development of new bioinformatic modeling approaches to combine multidimensional biomarkers that explain the different genetic, immunological and environmental determinants of therapeutic responses.

Serum Deoxyribonuclease 1-like 3 is a potential biomarker for diagnosis of ankylosing spondylitis

BACKGROUND

Ankylosing spondylitis (AS) is an autoimmune disease with high disability rate, and it is sometimes difficult to distinguish from generalized osteoarthritis (GOA). Deoxyribonuclease 1-like 3 (DNASE1L3) was associated with a variety of autoimmune diseases. However, the serum DNASE1L3 level in AS and GOA remain unreported. Herein, this study was designed to gauge serum DNASE1L3 level in patients with AS and GOA, and to discern the utility of serum DNASE1L3 as a biomarker for assessing the severity of patients with AS.

METHODS

The study population consisted of 60 patients with AS, 60 patients with GOA and 60 control subjects. Serum DNASE1L3 levels were measured using enzyme-linked immunosorbent assay (ELISA) assay. Disease activity were assessed with Bath Ankylosing Spondylitis Disease Activity Index (BASDAI) in AS patients.

RESULTS

Our data showed that serum DNASE1L3 levels were significantly higher in patients with AS than that of the healthy controls and patients with GOA. Serum DNASE1L3 levels in patients with AS were positively correlated with BASDAI scores, C3 and C-reactive protein (CRP). Furthermore, serum DNASE1L3 showed higher discriminatory accuracy in the diagnosis of AS from GOA (AUC = 0.851, sensitivity = 78.33% and specificity = 81.67%).

CONCLUSIONS

Elevated Serum DNASE1L3 levels in patients with AS were significantly associated with the clinic features and disease activity. DNASE1L3 could be a serum biomarker with a positive diagnostic value in patients with AS, and which could be used as a differential diagnostic indicator for GOA and AS.

HLA-B*27 subtypes and their implications in the pathogenesis of ankylosing spondylitis

Ankylosing spondylitis (AS) is a highly heritable kind of arthritis that affects the vertebral column. AS risk has been associated strongly with Human leukocyte antigen (HLA)-B*27. In fact, some HLA-B*27 subtypes have been associated with the increased disease risk, although some specific subtypes have not shown such associations. It is supposed that HLA-B*27 plays a major role in the etiopathogenesis of the disease. However, the difference in pathogenic outcomes of HLA-B*27 certain subtypes needs to be clarified. The purpose of this review article is to overview on the detailed implications of the HLA-B*27 subtypes in the etiopathogenesis of AS. Moreover, the role of ERAP1 in AS and its epistasis with HLA-B*27 have been reviewed.

I-BET151 inhibits expression of RANKL, OPG, MMP3 and MMP9 in ankylosing spondylitis in vivo and in vitro

Ankylosing spondylitis (AS) is characterized by osteoclastogenesis and inflammatory bone resorption. The present study aimed to investigate the effect of bromodomain and extra-terminal domain (BET) protein inhibitor I-BET151 on AS process. A total of 38 AS Chinese patients were recruited and a further 38 sex- and age-matched healthy participants were selected as control. The Bath AS Function Index and Bath AS Disease Activity Index were assessed in AS patients and levels of erythrocyte sedimentation rate and C-reactive protein were measured in AS and healthy groups. Serum from AS patients was used to induce MG63 osteoblasts and BET inhibitor I-BET151 at concentrations of 50, 100 and 200 ng/ml used for treatment of the cells. A HLA-B27/β2m transgenic AS Lewis rat model was established and treated with 30 mg/kg I-BET151 for 5 weeks. Levels of receptor activator of nuclear factor-κB ligand (RANKL), osteoprotegerin (OPG), matrix metalloproteinase (MMP)3, and MMP9 were measured using ELISA in vivo and additionally detected with western blotting and polymerase chain reaction in vitro. The levels of RANKL, OPG, MMP3 and MMP9 were upregulated in AS serum, AS serum treated MG63 cells and HLA-B27/β2m transgenic AS rats. Conversely, levels of RANKL, OPG, MMP3 and MMP9 were significantly inhibited in cells or animals treated with I-BET151. Overall, the results of the present study demonstrated that BET inhibitor I-BET151 suppresses levels of RANKL, OPG, MMP3 and MMP9 in AS in vivo and in vitro. I-BET151 may exhibit the potential to be used as a therapeutic in the treatment of AS patients.

Spondyloarthritis: Matrix Metalloproteinasesas Biomarkers of Pathogenesis and Response to Tumor Necrosis Factor (TNF) Inhibitors

The term spondyloarthritis (SpA) is used to describe a group of multifactorial chronic inflammatory diseases characterized by a predisposing genetic background and clinical manifestations typically involving the sacroiliac joint. The absence of pathognomonic clinical and/or laboratory findings generally results in a delay in diagnosis and, consequently, in treatment. In addition, 20–40% of SpA patients are non-responders to tumor necrosis factor (TNF) inhibitor therapies. Given these considerations, it is important to identify biomarkers that can facilitate the diagnosis and assessment of disease activity. As inflammation plays a key role in the pathogenesis of SpA, inflammatory mediators have been investigated as potential biomarkers for diagnosing the disease and predicting response to therapy. Some investigators have focused their attention on the role of matrix metalloproteinases (MMPs), which are known to be markers of synovial inflammation that is generated in the joint in reaction to inflammatory stimuli. Several studies have been carried out to verify if serum MMPs levels could be useful to diagnose SpA, to assess disease severity, and to predict response to TNF inhibitor therapy. The current review focuses on MMPs’ role in SpA pathogenesis, diagnosis and therapeutic implications.

Optimal Affinity of a Monoclonal Antibody: Guiding Principles Using Mechanistic Modeling

Affinity optimization of monoclonal antibodies (mAbs) is essential for developing drug candidates with the highest likelihood of clinical success; however, a quantitative approach for setting affinity requirements is often lacking. In this study, we computationally analyzed the in vivo mAb-target binding kinetics to delineate general principles for defining optimal equilibrium dissociation constant ([Formula: see text]) of mAbs against soluble and membrane-bound targets. Our analysis shows that in general [Formula: see text] to achieve 90% coverage for a soluble target is one tenth of its baseline concentration ([Formula: see text]), and is independent of the dosing interval, target turnover rate or the presence of competing ligands. For membrane-bound internalizing targets, it is equal to the ratio of internalization rate of mAb-target complex and association rate constant ([Formula: see text]). In cases where soluble and membrane-bound forms of the target co-exist, [Formula: see text] lies within a range determined by the internalization rate ([Formula: see text]) of the mAb-membrane target complex and the ratio of baseline concentrations of soluble and membrane-bound forms ([Formula: see text]). Finally, to demonstrate practical application of these general rules, we collected target expression and turnover data to project [Formula: see text] for a number of marketed mAbs against soluble (TNFα, RANKL, and VEGF) and membrane-bound targets (CD20, EGFR, and HER2).