Focal bone involvement in inflammatory arthritis: the role of IL17

The immune cells in modulating osteoclast formation and bone metabolism

Osteoclasts are pivotal in regulating bone metabolism, with immune cells significantly influencing both physiological and pathological processes by modulating osteoclast functions. This is particularly evident in conditions of inflammatory bone resorption, such as rheumatoid arthritis and periodontitis. This review summarizes and comprehensively analyzes the research progress on the regulation of osteoclast formation by immune cells, aiming to unveil the underlying mechanisms and pathways through which diseases, such as rheumatoid arthritis and periodontitis, impact bone metabolism.

Bone metabolism and inflammatory biomarkers in radiographic and non-radiographic axial spondyloarthritis patients: a comprehensive evaluation

Introduction

Axial spondyloarthritis (axSpA) is a heterogeneous disease that can be represented by radiographic axSpA (r-axSpA) and non-radiographic axSpA (nr-axSpA). This study aimed to evaluate the relationship between the markers of inflammation and bone turnover in r-axSpA patients and nr-axSpA patients.

Methods

A cross-sectional study included 29 r-axSpA patients, 10 nr-axSpA patients, and 20 controls matched for age and sex. Plasma markers related to bone remodeling such as human procollagen type 1 N-terminal propeptide (P1NP), sclerostin, tartrate-resistant acid phosphatase 5b (TRACP5b), receptor activator of nuclear factor kappa B ligand (RANKL), and osteoprotegerin (OPG) were measured by an ELISA kit. A panel of 92 inflammatory molecules was analyzed by proximity extension assay.

Results

R-axSpA patients had decreased plasma levels of P1NP, a marker of bone formation, compared to controls. In addition, r-axSpA patients exhibited decreased plasma levels of sclerostin, an anti-anabolic bone hormone, which would not explain the co-existence of decreased plasma P1NP concentration; however, sclerostin levels could also be influenced by inflammatory processes. Plasma markers of osteoclast activity were similar in all groups. Regarding inflammation-related molecules, nr-axSpA patients showed increased levels of serum interleukin 13 (IL13) as compared with both r-axSpA patients and controls, which may participate in the prevention of inflammation. On the other hand, r-axSpA patients had higher levels of pro-inflammatory molecules compared to controls (i.e., IL6, Oncostatin M, and TNF receptor superfamily member 9). Correlation analysis showed that sclerostin was inversely associated with IL6 and Oncostatin M among others.

Conclusion

Altogether, different inflammatory profiles may play a role in the development of the skeletal features in axSpA patients particularly related to decreased bone formation. The relationship between sclerostin and inflammation and the protective actions of IL13 could be of relevance in the axSpA pathology, which is a topic for further investigation.

RETRACTED ARTICLE: Secukinumab-induced paradoxical skin lesions, but successful treatment with tofacitinib in SAPHO syndrome: a case report

We, the Editors and Publisher of Journal of Dermatological Treatment, have retracted the following article:Li Luan & Chengzhi Lv (2023) Secukinumab-induced paradoxical skin lesions, but successful treatment with tofacitinib in SAPHO syndrome: a case report, Journal of Dermatological Treatment, DOI: 10.1080/09546634.2023.2193662Since publication of the article, concerns were raised by a reader regarding the lack of recorded patient consent to publish. Upon further investigation, it was determined that written consent for the publication was not obtained by the authors. The authors were contacted for an explanation and confirmed written consent for the publication was not obtained.As this represents a breach of the journal's editorial policies, we are therefore retracting the article. The corresponding author listed in this publication has been informed.We have been informed in our decision-making by our editorial policies and the COPE guidelines.The retraction article will remain online to maintain the scholarly record, but it will be digitally watermarked on each page as 'Retracted'.

Consequences of Aging on Bone

With the aging of the global population, the incidence of musculoskeletal diseases has been increasing, seriously affecting people's health. As people age, the microenvironment within skeleton favors bone resorption and inhibits bone formation, accompanied by bone marrow fat accumulation and multiple cellular senescence. Specifically, skeletal stem/stromal cells (SSCs) during aging tend to undergo adipogenesis rather than osteogenesis. Meanwhile, osteoblasts, as well as osteocytes, showed increased apoptosis, decreased quantity, and multiple functional limitations including impaired mechanical sensing, intercellular modulation, and exosome secretion. Also, the bone resorption function of macrophage-lineage cells (including osteoclasts and preosteoclasts) was significantly enhanced, as well as impaired vascularization and innervation. In this study, we systematically reviewed the effect of aging on bone and the within microenvironment (including skeletal cells as well as their intracellular structure variations, vascular structures, innervation, marrow fat distribution, and lymphatic system) caused by aging, and mechanisms of osteoimmune regulation of the bone environment in the aging state, and the causal relationship with multiple musculoskeletal diseases in addition with their potential therapeutic strategy.

Impact of autologous platelet-rich plasma therapy vs. hyaluronic acid on synovial fluid biomarkers in knee osteoarthritis: a randomized controlled clinical trial

Objective

Observe the effects of platelet-rich plasma (PRP) therapy on inflammatory cytokines in the synovial fluid of the knee joint of patients with KOA, and explore the effects of PRP intra-articular injection on the inflammation of the knee joint environment and the possible mechanism of action.

Methods

Seventy patients were randomized to undergo three blinded weekly intra-articular injections of PRP or hyaluronic acid (HA). The concentrations of inflammatory cytokines, including interleukin (IL)-6, IL-1β, tumor necrosis factor (TNF)-α, IL-8, IL-17A, IL-17F, IL-4, IL-5, and IL-10, in the synovial fluid were evaluated before the intervention and 1 month after the third injection. The Western Ontario and McMaster University (WOMAC) and visual analog scale (VAS) scores were used to assess pain and functional status of the knee joints in both groups before the intervention, immediately post-intervention, and 1, 3, 6, and 12 months after the intervention.

Results

Baseline characteristics were similar in both groups with no statistical difference. The IL-6, IL-1β, TNF-α, IL-17A, and IL-10 levels in the synovial fluid of the observation group decreased significantly after, vs. before, the intervention (p < 0.05), whereas the IL-8, IL-17F, and IL-4 levels decreased (p > 0.05) and IL-5 levels increased (p > 0.05). There was no statistically significant difference between inflammatory cytokine levels in the synovial fluid of the samples from the control group before and after the intervention (p > 0.05). There were no statistically significant differences between the two groups immediately after intervention (p > 0.05). At 1, 3, 6, and 12 months after intervention, the WOMAC and VAS scores were significantly better in the observation group than in the control group (p < 0.05).

Conclusion

Platelet plasma therapy can reduce the concentrations of inflammatory cytokines IL-6, IL-1β, TNF-α, IL-17A, and IL-10 in the synovial fluid of KOA patients, reduce the expression levels of IL-8, IL-17F, and IL-4, clear the pro-inflammatory factors, improve the inflammatory environment of the affected knee joint, and alleviate pain caused by inflammation. Thus, alleviating pain and improving knee function in patients with KOA.

Osteoimmunology of Spondyloarthritis

The mechanisms underlying the development of bone damage in the context of spondyloarthritis (SpA) are not completely understood. To date, a considerable amount of evidence indicates that several developmental pathways are crucially involved in osteoimmunology. The present review explores the biological mechanisms underlying the relationship between inflammatory dysregulation, structural progression, and osteoporosis in this diverse family of conditions. We summarize the current knowledge of bone biology and balance and the foundations of bone regulation, including bone morphogenetic protein, the Wnt pathway, and Hedgehog signaling, as well as the role of cytokines in the development of bone damage in SpA. Other areas surveyed include the pathobiology of bone damage and systemic bone loss (osteoporosis) in SpA and the effects of pharmacological treatment on focal bone damage. Lastly, we present data relative to a survey of bone metabolic assessment in SpA from Italian bone specialist rheumatology centers. The results confirm that most of the attention to bone health is given to postmenopausal subjects and that the aspect of metabolic bone health may still be underrepresented. In our opinion, it may be the time for a call to action to increase the interest in and focus on the diagnosis and management of SpA.

Increased synovial immunohistochemistry reactivity of TGF-β1 in erosive peripheral psoriatic arthritis

BACKGROUND

Immune and non-immune cells contribute to the pathology of chronic arthritis, and they can contribute to tissue remodeling and repair as well as disease pathogenesis. The present research aimed to analyze inflammation and bone destruction/regeneration biomarkers in patients with psoriatic arthritis (PsA), rheumatoid arthritis (RA), osteoarthritis (OA), and ankylosing spondylitis (AS).

METHODS

Samples were obtained from the inflamed knee of patients with knee arthritis who had been referred for undergoing arthroscopies. The synovial membrane was processed for pathological description, IHC analysis, and quantification of mRNA expression ratio by qRT-PCR. Serum levels of TGF-β1, IL-23, IL-6, IL-17 A, IL-22, Dkk1, Sclerostin, BMP2, BMP4, Wnt1, and Wnt5a were measured by ELISA. All these data were analyzed and compared with the demographic, clinical, blood tests, and radiological characteristics of the patients.

RESULTS

The synovial membrane samples were obtained from 42 patients for IHC, extraction, and purification of RNA for synovial mRNA expression analysis, and serum for measuring protein levels from 38 patients. IHC reactivity for TGF-β1 in the synovial tissue was higher in patients with psoriatic arthritis (p 0.036) and was positively correlated with IL-17 A (r = 0.389, p = 0.012), and Dkk1 (r = 0.388, p = 0.012). Gene expression of the IL-17 A was higher in PsA patients (p = 0.018) and was positively correlated with Dkk1 (r = 0.424, p = 0.022) and negatively correlated with BMP2 (r = -0.396, p = 0.033) and BMP4 (r = -0.472, p = 0.010). It was observed that IHC reactivity for TGF-β1 was higher in patients with erosive PsA (p = 0.024).

CONCLUSIONS

The IHC reactivity of TGF-β1 in synovial tissue was higher in patients with erosive psoriatic arthritis, and TGF-β1 was in relation to higher levels of gene expression of IL-17 A and Dkk1.

Anti-tumor necrosis factor alpha treatment does not influence serum levels of the markers associated with radiographic progression in ankylosing spondylitis

OBJECTIVES

The study aimed to determine the levels of change of the markers related to radiographic progression, such as Dickkopf-1 (DKK-1), sclerostin (SOST), bone morphogenetic protein (BMP)-2 and -4, and interleukin (IL)-17 and -23, in ankylosing spondyloarthritis (AS) during anti-tumor necrosis factor alpha (TNF-α) treatment.

PATIENTS AND METHODS

Fifty-three anti-TNF-α naïve AS patients (34 males, 19 females; median: 38 years; range, 20 to 52 years) refractory to conventional treatments meeting the modified New York criteria or Assessment of SpondyloArthritis International Society classification criteria were enrolled to this cross-sectional, controlled study between October 2015 and January 2017. Fifty healthy volunteers (35 males, 15 females; median: 36 years; range, 18 to 55 years) with similar age and sex characteristics were recruited. Serum DKK-1, BMP-2, BMP-4, SOST, IL-17, and IL-23 levels were measured in both groups. The serum levels of the markers were measured again after about two years (mean follow-up duration of 21.7±6.4 months) in AS patients who started anti-TNF-α treatment. Demographic, clinical characteristics, and laboratory parameters were recorded. The disease activity at the time of inclusion was assessed through the Bath Ankylosing Spondylitis Disease Activity Index.

RESULTS

Serum DKK-1, SOST, IL-17, and IL-23 levels in the AS group before anti-TNF-a treatment were significantly higher compared to the control group (p<0.01 for DKK-1, p<0.001 for others). There was no difference regarding serum BMP-4 levels, whereas BMP-2 levels were significantly higher in the control group (p<0.01). Forty (75.47%) AS patients had serum marker levels measured after anti-TNF-α treatment. No significant change was observed in the serum levels of these 40 patients measured 21.7±6.4 months after the initiation of anti-TNF-α treatment (p>0.05 for all).

CONCLUSION

In AS patients, there was no change in DKK-1/SOST, BMP, and IL-17/23 cascade with anti-TNF-α treatment. This finding may suggest that these pathways act independently of each other, and their local effects are not influenced by systemic inflammation.

Bone Health in Children with Rheumatic Disorders: Focus on Molecular Mechanisms, Diagnosis, and Management

Bone is an extremely dynamic and adaptive tissue, whose metabolism and homeostasis is influenced by many different hormonal, mechanical, nutritional, immunological and pharmacological stimuli. Genetic factors significantly affect bone health, through their influence on bone cells function, cartilage quality, calcium and vitamin D homeostasis, sex hormone metabolism and pubertal timing. In addition, optimal nutrition and physical activity contribute to bone mass acquisition in the growing age. All these factors influence the attainment of peak bone mass, a critical determinant of bone health and fracture risk in adulthood. Secondary osteoporosis is an important issue of clinical care in children with acute and chronic diseases. Systemic autoimmune disorders, like juvenile idiopathic arthritis, can affect the skeletal system, causing reduced bone mineral density and high risk of fragility fractures during childhood. In these patients, multiple factors contribute to reduce bone strength, including systemic inflammation with elevated cytokines, reduced physical activity, malabsorption and nutritional deficiency, inadequate daily calcium and vitamin D intake, use of glucocorticoids, poor growth and pubertal delay. In juvenile arthritis, osteoporosis is more prominent at the femoral neck and radius compared to the lumbar spine. Nevertheless, vertebral fractures are an important, often asymptomatic manifestation, especially in glucocorticoid-treated patients. A standardized diagnostic approach to the musculoskeletal system, including prophylaxis, therapy and follow up, is therefore mandatory in at risk children. Here we discuss the molecular mechanisms involved in skeletal homeostasis and the influence of inflammation and chronic disease on bone metabolism.

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.

Pharmacological Management of Synovitis, Acne, Pustulosis, Hyperostosis, and Osteitis Syndrome Syndrome: A Proposal of a Treatment Algorithm

ABSTRACT

Synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome is a rare chronic disease with marked clinical and radiological heterogeneity. It is characterized by a combination of dermatological and osteoarticular manifestations. The treatment of SAPHO syndrome is not yet codified. It includes several therapeutic options such as anti-inflammatory drugs, bisphosphonates, antibiotics, conventional disease-modifying antirheumatic drugs, and biological treatment.This article aims to provide an updated review of the different pharmacological options for SAPHO syndrome. We also propose a therapeutic algorithm for the management of this disease.

Prediction of the Molecular Mechanism of Eucommiae Cortex - Achyranthis Bidentatae Radix in the treatment of Osteoarthritis: Network Pharmacology and Molecular Docking

OBJECTIVE

To retrieve the core drug of osteoarthritis in clinic using Data Mining, predict the drug molecular action target through the Network Pharmacology, identify the key nodes of the interaction by combining with the related targtes of osteoarthritis, explore the pharmacological mechanism of Traditional Chinese Medicine against osteoarthritis and other possible mechanisms of actions.

METHODS

to retrieve the commonly used therapeutic formulations for osteoarthritis patients in clinical with PubMed, CNKI, VIP, CBM, WanFang Database and other databases, and screen out the core drugs through the Ancient and Modern Medical Case Cloud Platform and software Gephi, filter out the core drug molecules and targets combined with TCMSP database and the targets of osteoarthritis in Genecard and OMIM database, plunge those data into R project and Cytoscape to construct the intersection model of Drug molecule-osteoarthritis, establish PPI network and GO and conduct KEGG enrichment analysis with String database. Vina molecular docking was finally implemented to draw molecular docking diagram, and the results were analyzed after comprehensive analysis.

RESULTS

The core drug pairs were identified as "Eucommiae Cortex - Achyranthis Bidentatae Radix" through correlation analysis, complex network analysis based on the coefficient. "Eucommiae Cortex - Achyranthis Bidentatae Radix" can intervene cell behavior through multiple pathways and regulate cell metabolism, cytokine synthesis, oxidative and cellular immunity with the help of topology analysis in String Database.

CONCLUSIONS

The core molecules of Quercetin and Kaempferol derived from "Eucommia bark - achyranthes" can change the spatial conformation of PTGSs by hydrogen bonding with PTGSs, the hydrophobic bonds and van der Waals forces generated by Baicalein, Wogonin and β-carotene, thereby changing the activity of PTGSs and affecting bone properties the process of osteoarthritis.

Biomechanical Evaluation of the Transcortical and Transpedicular Trajectories for Pedicle Screw Insertion in Thoracolumbar Fracture Fixation for Ankylosing Spondylitis

Background: Ankylosing spondylitis (AS) is a chronic disorder characterized by an imbalance between bone formation and resorption. Spinal fractures often occur after minor trauma in patients with AS. For thoracolumbar fractures, transpedicular screw (TPS) fixation through the posterior approach has been suggested. The cortical bone trajectory (CBT) technique has also been used to prevent screw pull-out in patients with poor bone quality. The aim of current study was to assess the biomechanical characteristics of the TPS and CBT technique in thoracolumbar AS fracture fixation by finite element analysis.

Methods: The three-dimensional finite element models of the AS spine were created. The CBT and TPS methods of screw insertion were used in AS spinal fracture models. An intact AS spine model was considered the control. An axial force and torsion in rotation, flexion/extension and lateral flexion were applied in all models in CBT, TPS, and control groups.

Results: The AS spine showed similar construct stiffness after posterior fixation by CBT and TPS techniques under axial, rotational, and flexion/extension loading conditions. The TPS technique showed better intact stability under all loading conditions. Similarly, the TPS technique provided superior fracture regional stability against axial and rotational loads than did the CBT technique. The maximum von Mises stresses were 1714.4 ± 129.8 MPa and 1208.7 ± 107.3 MPa (p < 0.001), which occurred in the CBT and TPS groups under compressive loading.

Conclusions: The TPS technique provides better biomechanical strength under axial, rotational, flexion/extension, and lateral flexion loading than does the CBT technique. Compared with CBT, TPS is more effective in maintaining the stability of AS thoracolumbar fractures from a finite element analysis perspective.

IL17F: A Possible Risk Marker for Spondyloarthritis in HLA-B*27 Negative Brazilian Patients

HLA-B*27 is an important marker for spondyloarthritis (SpA), however, many SpA patients are HLA-B*27 negative. Thus, the aim of this study was to investigate the influence of IL17, TNF and VDR gene polymorphisms in SpA patients who were HLA-B*27 negative. This case-control study was conducted in 158 patients [102 patients with ankylosing spondylitis (AS) and 56 with psoriatic arthritis (PsA)] and 184 controls. HLA-B*27 genotyping was performed using PCR-SSP and IL17A (rs2275913), IL17F (rs763780), TNF-308 (rs1800629), TNF-238 (rs361525), FokI C>T (rs2228570), TaqI C>T (rs731236), ApaI A>C (rs7975232), and BsmI C>T (rs1544410) using PCR-RFLP. Statistical analyses were performed by Chi-square and logistic regression using OpenEpi and SNPStats software. The IL17F C allele frequency was higher in patients with SpA, AS and PsA compared to controls. The IL17F T/C genotype frequency was higher in SpA patients in an overdominant inheritance model and when men and women were separately analyzed. IL17A_IL17F AC haplotype was significantly associated to the risk for SpA patients. As for VDR, the ApaI a/a was a potential risk factor for SpA in men. In conclusion, IL17F C variant contributed to the risk of SpA in Brazilian patients who were HLA-B*27 negative and could be a potential marker for SpA.

Exploring IL-17 in spondyloarthritis for development of novel treatments and biomarkers

Spondyloarthritis (SpA) is an umbrella term describing a family of chronic inflammatory rheumatic diseases. These diseases are characterised by inflammation of the axial skeleton, peripheral joints, and entheseal insertion sites throughout the body which can lead to structural joint damage including formation of axial syndesmophytes and peripheral osteophytes. Genetic evidence, preclinical and clinical studies indicate a clear role of interleukin (IL)- 23 and IL-17 as mediators in SpA pathogenesis. Targeting the IL-23/-17 pathways seems an efficient strategy for treatment of SpA patients, and despite the remaining challenges the pathway holds great promise for further advances and improved therapeutic opportunities. Much research is focusing on serological markers and imaging strategies to correctly diagnose patients in the early stages of SpA. Biomarkers may facilitate personalised medicine tailored to each patient's specific disease to optimise treatment efficacy and to monitor therapeutic response. This narrative review focuses on the IL-17 pathway in SpA-related diseases with emphasis on its role in pathogenesis, current approved IL-17 inhibitors, and the need for biomarkers reflecting core disease pathways for early diagnosis and measurement of disease activity, prognosis, and response to therapy.

Safety of secukinumab for the treatment of active ankylosing spondylitis

Introduction: Secukinumab is a fully human monoclonal antibody which targets and neutralizes interleukin (IL)-17A, a cytokine that plays an important role in the pathophysiology of ankylosing spondylitis (AS). Secukinumab is the first IL-17A inhibitor approved for the treatment of AS.Areas covered: This paper aimed to evaluate the role of IL-17 in human beings, and the blocking of this cytokine with secukinumab while reviewing its efficacy and safety in the treatment of AS from data of MEASURE clinical trials.Expert opinion: MEASURE clinical trials showed efficacy and safety of secukinumab in patients with AS. Mild infections were the most frequent adverse event observed. Mucocutaneous candidiasis was a relatively common side effect due to the role of IL-17A in mucocutaneous defense against extracellular organisms. Secukinumab remained generally well tolerated over the longer-term. The combination of efficacy and safety makes secukinumab a good option of treatment for patients with AS refractory to non-steroidal anti-inflammatory drugs.

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.

Secukinumab provides sustained low rates of radiographic progression in psoriatic arthritis: 52-week results from a phase 3 study, FUTURE 5

Objective

To evaluate the effect of secukinumab on radiographic progression through 52 weeks in patients with PsA from the FUTURE 5 study.

Methods

Patients with active PsA, stratified by prior anti-TNF use (naïve or inadequate response), were randomized to s.c. secukinumab 300 mg load (300 mg), 150 mg load (150 mg), 150 mg no load regimens or placebo at baseline, at weeks 1, 2 and 3 and every 4 weeks starting at week 4. Radiographic progression was assessed by change in van der Heijde-modified total Sharp score (vdH-mTSS; mean of two readers). Statistical analysis used a linear mixed-effects model (random slope) at weeks 24 and 52, and observed data at week 52. Assessments at week 52 included additional efficacy endpoints (non-responders imputation and mixed-effects models for repeated measures) and safety.

Results

The majority (86.6%) of patients completed 52 weeks of treatment. The proportion of patients with no radiographic progression (change from baseline in vdH-mTSS ⩽0.5) was 91.8, 85.2 and 87.2% in 300, 150 and 150 mg no load groups, respectively, at week 52. The change in vdH-mTSS from baseline to week 52 using random slope [mean change (s.e.)] was –0.18 (0.17), 0.11 (0.18) and –0.20 (0.18) in 300, 150 and 150 mg no load groups, respectively; the corresponding observed data [mean change (s.d.)] was –0.09 (1.02), 0.13 (1.39) and 0.21 (1.15). Clinical efficacy endpoints were sustained, and no new or unexpected safety signals were reported through 52 weeks.

Conclusion

Secukinumab 300 and 150 mg with or without s.c. loading regimen provided sustained low rates of radiographic progression through 52 weeks of treatment.

Trial registration

ClinicalTrials.gov, http://clinicaltrials.gov, NCT02404350.

Role of the IL-23 pathway in the pathogenesis and treatment of enthesitis in psoriatic arthritis

INTRODUCTION

Enthesitis is a key feature of spondyloarthritis (SpA). Several studies have underlined the role of interleukin (IL)-23 in SpA development as a crucial cytokine in the pathogenesis of enthesitis.

AREA COVERED

This review summarizes recent evidence of the role of IL-23 in the pathogenesis of and as a target of the treatment of enthesitis. We review the definition, diagnosis and clinical impact of enthesitis and its connection with microbial infections, gut dysbiosis, and mechanical stress. We also review clinical trials and real-life studies of drugs targeting the p19 or p40 subunits of IL-23.

EXPERT OPINION

Novel therapies targeting the p19 or p40 subunit of IL-23 appear to be promising treatment options for patients with enthesitis. Although we are currently unable to identify the best therapeutic window to target IL-23 in SpA disease evolution, the promising ability of this therapy to control the gut-entheseal axis is increasing our knowledge of SpA pathogenesis.

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.

Quantification of pro-inflammatory cytokines and osteoclastogenesis markers in successful and failed orthodontic mini-implants

Objectives:

Miniscrew has been frequently used, considering that anchorage control is a critical point in orthodontic treatment, and its failure, the main adverse problem. Using two groups of stable (successful) and unstable (failed) mini-implants, this in vivo study aimed to quantify proinflammatory cytokines IL-1 α, IL-6, IL-17, and TNF-α and osteoclastogenesis marker RANK, RANKL, and OPG in gingival tissue, using the real-time polymerase chain reaction technique.

Methodology:

Thirteen patients of both sexes (11-49 years old) under orthodontic treatment were selected, obtaining 11 successful and 7 failed mini-implants. The mini-implants were placed and removed by the same surgeon, in both jaws. The mean time of permanence in the mouth was 29.4 months for successful and 7.6 months for failed mini-implants. At removal time, peri-mini-implant gingival tissue samples were collected and processed for quantification of the proinflammatory cytokines and osteoclastogenesis markers. Nonparametric Wilcoxon rank-sum test considering the clusters and Kruskal-Wallis test were used for statistical analysis (α=0.05).

Results:

No significant difference (p>0.05) was observed between the groups for either quantification of cytokines or osteoclastogenesis markers, except for IL-6 (p<0.05).

Conclusions:

It may be concluded that the expression of IL-1α, IL-17, TNF-α, RANK, RANKL, and OPG in peri-implant gingival tissue were not determinant for mini-implant stability loss, but the higher IL-6 expression could be associated with mini-implant failure.

Psoriatic Arthritis: What is Happening at the Joint?

Psoriatic arthritis (PsA) is a heterogeneous and inflammatory disease with diverse clinical manifestations, including psoriasis, nail psoriasis, peripheral joint disease, axial joint disease, enthesitis, and dactylitis. Typically, this varied clinical presentation complicates the clinician's ability to distinguish PsA from other forms of arthritis. In the synovium of individuals with PsA, upregulation of the genes WNT3A, BMPR2, and TGFBR1 results in bone erosion and new bone formation, a pattern unique to the disease. Additionally, genes associated with angiogenesis and vascularization such as VEGF and TGFB1 facilitate inflammation and joint damage. Gross pathogenesis of PsA is driven by proinflammatory cytokines, and key cytokines affecting joint structures include tumor necrosis factor-α, interleukin (IL)-6, IL-17A, IL-21, IL-22, and IL-23. Early diagnosis is critical for providing treatment that prevents irreversible disease progression and function loss. This narrative review discusses differentiation of PsA from other forms of arthritis. Additionally, we detail the role of cytokines at the joint in mediating PsA pathogenesis.Funding: Novartis Pharmaceuticals Corporation.

Implication of IL-17 in Bone Loss and Structural Damage in Inflammatory Rheumatic Diseases

Proinflammatory cytokines play an important role in the systemic and focal bone loss associated with chronic inflammatory diseases. Targeting these cytokines with biologics and small molecules has led to a major improvement of the bone health of patients with inflammatory arthritis. Cytokines from the IL-17 family have been shown to be involved in the pathogenesis of several diseases such as spondyloarthritis, psoriatic arthritis, or psoriasis. IL-17A has been the first described and the most studied. The recent development of targeted therapies against IL-17A or its receptor and their efficacy has confirmed the importance of this cytokine in the development of inflammatory diseases. The aim of this review was to describe the effects of the IL-17 family and more particularly of IL-17A on bone and cartilage tissues. At the cellular level, IL-17A is proosteoclastogenic whereas its effects on osteoblasts depend on the stage of differentiation of these cells. In vivo, IL-17A is not required for normal bone homeostasis but plays an important role in bone loss notably in an ovariectomized mouse model of osteoporosis. Preliminary data from clinical trials showed a stabilisation of bone density in patients treated with anti-IL-17A antibodies. IL-17A plays a central role in the cartilage damage through the induction of collagenases and by decreasing the expression of their inhibitors in synergy with the other proinflammatory cytokines. The prevention of structural damage by anti-IL-17A therapies has been demonstrated in several pivotal clinical trials. Overall, blocking the IL-17A pathway seems to have a positive effect on the bone and cartilage damage observed in inflammatory arthritis. Differences and specificity of these effects compared to those already described with other biologics such as anti-TNF therapies remain to be explored.

IL17RC affects the predisposition to thoracic ossification of the posterior longitudinal ligament

Background

Thoracic ossification of the posterior longitudinal ligament (T-OPLL) can cause thoracic spinal stenosis, which results in intractable myelopathy and radiculopathy. The etiology of T-OPLL is unknown and the condition is difficult to treat surgically. Whole-genome sequencing identified a genetic variant at rs199772854 of the interleukin 17 receptor C (IL17RC) gene as a potentially pathogenic locus associated with T-OPLL. We aimed to determine whether the rs199772854A site mutation causes abnormal expression of the IL17RC in Han Chinese patients with T-OPLL and predict the possible pathogenic mechanisms of T-OPLL. Analyses were performed to determine whether IL17RC is involved in the pathogenicity of T-OPLL.

Methods

Peripheral blood and OPLL tissue were collected from a total of 72 patients with T-OPLL disease (36 patients carrying the rs199772854A site mutation in IL17RC and 36 wild-type patients). The expression of IL17RC was analyzed by enzyme-linked immunosorbent assay, reverse transcription-quantitative polymerase chain reaction, immunohistochemistry, and Western blotting.

Results

rs199772854A mutation resulted in markedly increased IL17RC gene expression levels in peripheral blood samples and the OPLL tissue obtained following clinical surgery (P < 0.05).

Conclusions

The results suggest that the rs199772854A site mutation of IL17RC can significantly increase the expression of IL17RC. The IL17RC gene rs199772854A site polymorphism is a potential pathogenic mutation in T-OPLL disease, which may be associated with the occurrence of T-OPLL.

Kadsura heteroclita stem suppresses the onset and progression of adjuvant-induced arthritis in rats

BACKGROUND

Rheumatoid arthritis (RA) is a chronic autoimmune diseased state, characterized by hyperplasia of the synovial membrane, degradation of cartilage, and bone erosion of diarthrodial joints. Kadsura heteroclita (Roxb) Craib (Schizandraceae), a traditional Tujia ethnomedicine called Xue Tong in China, has been long used for the prevention and treatment of rheumatic and arthritic diseases, especially in the southern China. This study aimed to evaluate anti-arthritic effects of the ethanol extract of Kadsura heteroclita stems (KHS) on complete Freund's adjuvant (CFA)-induced arthritis (AIA) in rats, as well as to explore the underlying mechanisms of anti-arthritis.

METHODS

AIA was established in male Sprague-Dawley (SD) rats as described previously, and animals were daily treated by gavage with KHS ethanol extract (200, 400, or 800 mg/kg) or vehicle (0.3% CMCNa) throughout the 30-day experiment. The incidence and severity of arthritis were evaluated using clinical parameters. At the end of experiments, tissue swelling and bone destruction of the hind paws were assessed by computed tomography (CT) and histopathological analyses. Serum levels of tumor necrosis factor (TNF-α), interleukin-1β (IL-1β), IL-6, and IL-17A and IL-17F were measured by ELISA, and protein expression of matrix metalloproteinases-1 (MMP-1), MMP-3 and tissue inhibitor of MMP-1 (TIMP-1) were detected by Western blot.

RESULTS

Treatment with KHS dose-dependently inhibited paw swelling and reduced arthritis scores of AIA rats. CT images displayed that KHS remarkably protected AIA rats from tissue swelling and bone erosion of joints. Histopathological analyses revealed that KHS markedly reduced inflammatory cell infiltration, synovial proliferation, and the formation of pannus in the ankle joints of AIA rats. KHS was found to significantly suppress the production of TNF-α, IL-1 β, IL-6, IL-17A and IL-17F, inhibited the protein expression of MMP-1 and MMP-3, and elevated the protein expressions of TIMP-1.

CONCLUSION

KHS demonstrates potential anti-arthritic effects via inhibiting pivotal mediators of inflammation and cartilage destruction. This study strongly supports identification and isolation of active fractions of KHS which would be a potential candidate for further investigation as a new anti-arthritic botanical drug.

Altered morpho-functional features of bones in autoimmune disease-prone BXSB/MpJ- Yaa mice

IMPACT STATEMENT

Bone disease, such as osteoporosis and rheumatoid arthritis, increases because of the progression of an aging society. Autoimmune disease are important and predisposing factors for the pathogenesis of the bone disease; however, the pathological mechanism is unclear. We have demonstrated that systemic autoimmune disease in BXSB/MpJ- Yaa is closely associated with the morpho-functional abnormalities of bones including bone marrow and has complicated pathology. The abnormalities are characterized by altered regulations of serum calcium, anemia tendency, and hematopoiesis with increased WBCs and decreased PLs, short length and low mass of long bones, imbalance in the populations of osteoclasts and osteoblasts, and increased expression of candidate genes for causing and/or exacerbating their phenotypes. Therefore, BXSB/MpJ- Yaa serves as a model to elucidate bone phenotypes in systemic autoimmune disease that would be affected by the factors in the bone as well as the other immune and/or mineral metabolism organs both in human and experimental medicine.

Recent advances in ankylosing spondylitis: understanding the disease and management

The term spondyloarthritis refers to a group of immune-mediated diseases characterised by inflammation of the axial skeleton, peripheral joints, and entheses. Ankylosing spondylitis (AS) is the most common and characteristic of these entities and even though it was first described over two centuries ago, the understanding of the underlying disease mechanism remains incomplete. It is known that around 40% of patients with AS have subclinical bowel inflammation, suggesting that the origin of the disease could be in the gut. Also, more genes and new molecules have demonstrated a role in the pathogenesis of AS. In this review, we analyse the latest therapies for spondyloarthritis and the most relevant discoveries over the last three years, together with their implications for different aspects of the disease.

The role of secukinumab in the treatment of psoriatic arthritis and ankylosing spondylitis

Psoriatic arthritis and ankylosing spondylitis are chronic inflammatory diseases that can cause significant disability. The commercialization of the first tumour necrosis factor (TNF) inhibitors led to a radical improvement of the quality of life of people affected by these conditions; however, response was not universal, highlighting the need for alternative therapeutic targets. Secukinumab is a monoclonal interleukin (IL)-17A inhibitor which has been proven efficacious for psoriatic arthritis and ankylosing spondylitis in recent clinical trials. Dactylitis, enthesitis, skin and nails are some of the domains in which the inhibition of IL-17 has shown significant improvements apart from the joints. Its safety profile and satisfactory medium- to long-term outcome data are some of the aspects suggesting its potential impact in treatment protocols in the short term.

Serum CCL11 level is associated with radiographic spinal damage in patients with ankylosing spondylitis

The clinical significance of C-C motif chemokine11 (CCL11) in bone metabolism in ankylosing spondylitis (AS) is not clearly elucidated. Thus, this cross-sectional study aimed to compare serum levels of CCL11 between patients with AS and healthy controls and to investigate the relationship between serum levels of CCL11 and radiographic spinal damage in patients with AS. We consecutively recruited 55 male patients with AS and 26 age- and sex-matched healthy controls. Serum levels of CCL11, tumor necrosis factor-α (TNF-α), interleukin-17, and Dickkopf-1 (DKK-1) were measured with commercially available enzyme-linked immunosorbent assay kits. Radiographs were scored according to the modified Stoke ankylosing spondylitis spine score (mSASSS), and syndesmophytes were defined as mSASSS ≥ 2. The serum levels of CCL11 in AS patients with syndesmophytes were significantly higher than those in AS patients without syndesmophytes (p = 0.007) and healthy controls (p = 0.006). In AS patients, the serum levels of CCL11 were significantly and positively correlated with mSASSS (p = 0.006), number of syndesmophytes (p = 0.029). After adjusting for confounding factors, elevated serum levels of CCL11 were associated with increased mSASSS (β = 0.007, p = 0.03) and higher risk for the presence of syndesmophytes (OR 2.34 per 50 pg/ml increase, p = 0.012) in AS patients. We found that the serum level of CCL11 was associated with structural damage in patients with AS, suggesting that CCL11 may serve as a promising biomarker for new bone formation in AS.

Nanotopography-based strategy for the precise manipulation of osteoimmunomodulation in bone regeneration

Immune cells play vital roles in regulating bone dynamics. Successful bone regeneration requires a favourable osteo-immune environment. The high plasticity and diversity of immune cells make it possible to manipulate the osteo-immune response of immune cells, thus modulating the osteoimmune environment and regulating bone regeneration. With the advancement in nanotechnology, nanotopographies with different controlled surface properties can be fabricated. On tuning the surface properties, the osteo-immune response can be precisely modulated. This highly tunable characteristic and immunomodulatory effects make nanotopography a promising strategy to precisely manipulate osteoimmunomdulation for bone tissue engineering applications. This review first summarises the effects of the immune response during bone healing to show the importance of regulating the immune response for the bone response. The plasticity of immune cells is then reviewed to provide rationales for manipulation of the osteoimmune response. Subsequently, we highlight the current types of nanotopographies applied in bone biomaterials and their fabrication techniques, and explain how these nanotopographies modulate the immune response and the possible underlying mechanisms. The effects of immune cells on nanotopography-mediated osteogenesis are emphasized, and we propose the concept of "nano-osteoimmunomodulation" to provide a valuable strategy for the development of nanotopographies with osteoimmunomodulatory properties that can precisely regulate bone dynamics.

IL-23/Th17 targeted therapies in SAPHO syndrome. A case series

SAPHO syndrome is a rare entity with skin and rheumatologic inflammatory presentation. The treatment is not standardized, and in case of inadequate response to anti-inflammatory drugs, the use of anti-TNF or anti-IL-1 biologic treatments has been reported. The IL-23/Th17 axis may be involved in SAPHO syndrome. We report the results of six courses of IL-23 and IL-17 targeted therapies (3 ustekinumab and 3 secukinumab) in patients with SAPHO syndrome unresponsive to previous treatments (csDMARDs and bDMARDs). With a mean treatment duration of 5.5 months, improvement of skin symptoms was noticed in three cases, one improvement with secukinumab and two remissions (one with secukinumab, one with ustekinumab). Regarding the rheumatic symptoms, no major improvement was obvious under any of the six treatment courses. No particular safety concerns were reported, except cases of paradoxical psoriasis flare in one under ustekinumab and the other case under secukinumab.

Mechanistic rationales for targeting interleukin-17A in spondyloarthritis

The term spondyloarthritis (SpA) is used to describe a group of inflammatory autoimmune diseases, including ankylosing spondylitis and psoriatic arthritis, with common genetic risk factors and clinical features. SpA is clinically distinct from rheumatoid arthritis and typically affects the spine, sacroiliac joints, entheses, and, less commonly, peripheral joints. Although the pathogenesis of SpA is not fully understood, recent findings have identified the interleukin (IL)-17 pathway as a key mediator of disease pathogenesis. Clinical evidence for the efficacy of IL-17A inhibition by biologic agents was initially shown in patients with chronic plaque psoriasis, another autoimmune disease mediated by the IL-17 pathway. Subsequently, similar positive efficacy for inhibition of IL-17A was seen in patients with ankylosing spondylitis and psoriatic arthritis. Inhibition of IL-17A may also improve cardiovascular and metabolic comorbidities often found in patients with SpA because studies have linked these disorders to the IL-17 pathway. In this review, we will examine key preclinical studies that demonstrated the mechanistic role of IL-17A in the development SpA and discuss how these observations were translated into clinical practice.