Analysis of SF and plasma cytokines provides insights into the mechanisms of inflammatory arthritis and may predict response to therapy

Pulmonary pharmacodynamics of an anti-GM-CSFRα antibody enables therapeutic dosing that limits exposure in the lung

Pulmonary alveolar proteinosis is associated with impaired alveolar macrophage differentiation due to genetic defects in the granulocyte macrophage colony-stimulating factor (GM-CSF) axis or autoantibody blockade of GM-CSF. The anti-GM-CSFRα antibody mavrilimumab has shown clinical benefit in patients with rheumatoid arthritis, but with no accompanying pulmonary pathology observed to date. We aimed to model systemic versus pulmonary pharmacodynamics of an anti-GM-CSFRα antibody to understand the pharmacology that contributes to this therapeutic margin. Mice were dosed intraperitoneal with anti-GM-CSFRα antibody, and pharmacodynamics bioassays for GM-CSFRα inhibition performed on blood and bronchoalveolar lavage (BAL) cells to quantify coverage in the circulation and lung, respectively. A single dose of 3 mg/kg of the anti-GM-CSFRα antibody saturated the systemic cellular pool, but dosing up to 10 times higher had no effect on the responsiveness of BAL cells to GM-CSF. Continued administration of this dose of anti-GM-CSFRα antibody for 7 consecutive days also had no inhibitory effect on these cells. Partial inhibition of GM-CSFRα function on cells from the BAL was only observed after dosing for 5 or 7 consecutive days at 30 mg/kg, 10-fold higher than the proposed therapeutic dose. In conclusion, dosing with anti-GM-CSFRα antibody using regimes that saturate circulating cells, and have been shown to be efficacious in inflammatory arthritis models, did not lead to complete blockade of the alveolar macrophages response to GM-CSF. This suggests a significant therapeutic window is possible with GM-CSF axis inhibition.

Inflammatory cytokine levels, disease activity, and function of patients with rheumatoid arthritis treated with combined conventional disease-modifying antirheumatic drugs or biologics

The objective of this study was to compare the effects of treatment by combined conventional disease-modifying antirheumatic drugs (cDMARDs) or biologics on cytokines, disease activity, and function in rheumatoid arthritis (RA). Sera from a cohort of 81 patients with long-standing RA treated with combined cDMARDs or biologics were measured for 12 cytokines. Comparisons of serum cytokine concentrations with treatment types (combination 2, 3 cDMARDs or biologics), serologic status (positivity for RF and anti-cyclic citrullinated peptide antibody (anti-CCP Ab)), DAS28-ESR, and function were performed. Spearman correlation coefficients between individual cytokines and clinical parameters were explored. Approximately half of the patients were prescribed two cDMARDs. Mean duration of current treatment was 42 months. More than 70 % had moderate disease activity or normal function/slight disability. Serum concentrations of interleukin (IL)-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-17A, IL-23, IL-33, interferon (IFN)-γ, granulocyte monocyte-colony stimulating factor (GM-CSF), and TNF-α in patients taking combined cDMARDs did not significantly differ from those on biologics. Seventy-nine serum samples (97.5 %) had undetectable levels of 1 to 10 cytokines. Concentrations of several cytokines were significantly higher in patients with moderate to high disease activity, seropositive or poor functional status. Weak correlations between cytokine levels and RA disease activity or function were demonstrated. The highest correlation coefficients were observed with IL-33, IL-8, and IL-6. Long-term treatment with cDMARDs did not differ from biologics with respect to cytokine concentrations, disease activity, and function. The cytokine profiles in established RA were mainly those produced from effector cells, especially IL-6, IL-8, and IL-33. Both IL-8 and IL-33 may be potential biomarkers and/or treatment targets in patients with late RA.

Tocilizumab in refractory rheumatoid arthritis: long-term efficacy, safety, and tolerability beyond 2 years

Objectives

To evaluate the long-term efficacy and safety of tocilizumab (TCZ) in clinical patients with rheumatoid arthritis (RA) refractory to synthetic disease-modifying antirheumatic drugs, anti-tumor necrosis factor agents, and B-cell depletion therapy with rituximab (RTX).

Methods

We conducted a single-center retrospective study of 22 patients with RA treated with TCZ. We collected data including demographics and medication histories. We recorded clinical parameters including tender joint counts and swollen joint counts, and laboratory parameters including inflammatory makers and lipid profiles over regular intervals of TCZ treatment.

Results

In all, 22 patients with RA were included, 20 of whom were female. The median age at the first dose of TCZ was 62 years (range: 35–75 years). The mean duration of the disease from diagnosis with RA to May 2015 was 15.7 years (range: 6–30 years). A total of 15 out of 22 patients remained on TCZ at the end of the study, and in all, there was an improvement in markers of disease activity following initiating TCZ. The effect was sustained for a mean of 35 months (SD±15.5 months, range: 9–72 months). Of the 17 patients who failed to respond to RTX previously, 12 patients remained on TCZ. In all, eight out of 22 patients developed adverse events, five of whom discontinued TCZ. In contrast to previously documented short-term data, TCZ did not result in a statistically significant (P<0.05) long-term deterioration in lipid profile for any of the lipid parameters measured in our cohort (mean ± SD at initiation of TCZ to most recent follow-up: total cholesterol 5.25±1.05 to 5.28±0.77 mmol/L, high-density lipoprotein 1.72±0.54 to 1.67±0.43 mmol/L, low-density lipoprotein 3.05±0.98 to 2.98±0.81 mmol/L, and cholesterol to high-density lipoprotein ratio 3.41±1.23 to 3.40±1.22).

Conclusion

The efficacy of TCZ in patients with RA refractory to disease-modifying drugs, including anti-tumor necrosis factor blockade and RTX, is sustained over 3 years. TCZ confers a good safety profile in the long term even in patients who previously developed adverse events to other rheumatic drugs. In the long run, there is no statistically significant deterioration in lipid profile during treatment with TCZ.

Differential changes in gene expression in human neutrophils following TNF-α stimulation: Up-regulation of anti-apoptotic proteins and down-regulation of proteins involved in death receptor signaling

Responses of human neutrophils to TNF‐α are complex and multifactorial. Exposure of human neutrophils to TNF‐α in vitro primes the respiratory burst, delays apoptosis and induces the expression of several genes including chemokines, and TNF‐α itself. This study aimed to determine the impact of TNF‐α exposure on the expression of neutrophil genes and proteins that regulate apoptosis. Quantitative PCR and RNA‐Seq, identified changes in expression of several apoptosis regulating genes in response to TNF‐α exposure. Up‐regulated genes included TNF‐α itself, and several anti‐apoptotic genes, including BCL2A1, CFLAR (cFLIP) and TNFAIP3, whose mRNA levels increased above control values by between 4‐20 fold (n = 3, P < 0.05). In contrast, the expression of pro‐apoptotic genes, including CASP8, FADD and TNFRSF1A and TNFRSF1B, were significantly down‐regulated following TNF‐α treatment. These changes in mRNA levels were paralleled by decreases in protein levels of caspases 8 and 10, TRADD, FADD, TNFRSF1A and TNFRSF1B, and increased cFLIP protein levels, as detected by western blotting. These data indicate that when neutrophils are triggered by TNF‐α exposure, they undergo molecular changes in transcriptional expression to up‐regulate expression of specific anti‐apoptotic proteins and concomitantly decrease expression of specific proteins involved in death receptor signaling which will alter their function in TNF‐α rich environments.

LPS-Induced G-CSF Expression in Macrophages Is Mediated by ERK2, but Not ERK1

Granulocyte colony-stimulating factor (G-CSF) selectively stimulates proliferation and differentiation of neutrophil progenitors which play important roles in host defense against infectious agents. However, persistent G-CSF production often leads to neutrophilia and excessive inflammatory reactions. There is therefore a need to understand the mechanism regulating G-CSF expression. In this study, we showed that U0126, a MEK1/2 inhibitor, decreases lipopolysaccharide (LPS)-stimulated G-CSF promoter activity, mRNA expression and protein secretion. Using short hairpin RNA knockdown, we demonstrated that ERK2, and not ERK1, involves in LPS-induced G-CSF expression, but not LPS-regulated expression of TNF-α. Reporter assays showed that ERK2 and C/EBPβ synergistically activate G-CSF promoter activity. Further chromatin immunoprecipitation (ChIP) assays revealed that U0126 inhibits LPS-induced binding of NF-κB (p50/p65) and C/EBPβ to the G-CSF promoter, but not their nuclear protein levels. Knockdown of ERK2 inhibits LPS-induced accessibility of the G-CSF promoter region to DNase I, suggesting that chromatin remodeling may occur. These findings clarify that ERK2, rather than ERK1, mediates LPS-induced G-CSF expression in macrophages by remodeling chromatin, and stimulates C/EBPβ-dependent activation of the G-CSF promoter. This study provides a potential target for regulating G-CSF expression.

Antibody arrays in biomarker discovery

All of life is regulated by complex and organized chemical reactions that help dictate when to grow, to move, to reproduce, and to die. When these processes go awry, or are interrupted by pathological agents, diseases such as cancer, autoimmunity, or infections can result. Cytokines, chemokines, growth factors, adipokines, and other chemical moieties make up a vast subset of these chemical reactions that are altered in disease states, and monitoring changes in these molecules could provide for the identification of disease biomarkers. From the first identification of carcinoembryonic antigen, to the discovery of prostate-specific antigen, to numerous others described within, biomarkers of disease are detectable in a plethora of sample types. The growing number of biomarkers for infection, autoimmunity, and cancer allow for increasingly early detection, to identification of novel drug targets, to prognostic indicators of disease outcome. However, more and more studies are finding that a single cytokine or growth factor is insufficient as a true disease biomarker and that a more global perspective is needed to understand true disease biology. Such a broad view requires a multiplexed platform for chemical detection, and antibody arrays meet and exceed this need by performing this detection in a high-throughput fashion. Herein, we will discuss how antibody arrays have evolved, and how they have helped direct new drug target design, helped identify therapeutic disease markers, and helped in earlier disease detection. From asthma to renal disease, and neurological dysfunction to immunologic disorders, antibody arrays afford a bright future for new biomarkers discovery.

Novel immunostimulatory effects of osteoclasts and macrophages on human γδ T cells

It has been widely reported that T cells are capable of influencing osteoclast formation and bone remodelling, yet relatively little is known of the reciprocal effects of osteoclasts for affecting T cell function and/or activity. In this study we investigated the effects of human osteoclasts on the function of γδ T cells, a subset of non-CD4(+) T cells implicated in a variety of inflammatory disease states. γδ T cells and CD4(+) T cells were isolated from peripheral blood of healthy volunteers and were co-cultured with autologous mature osteoclasts (generated by treatment with M-CSF and RANKL) before phenotypical and functional changes in the T cell populations were assessed. Macrophages, osteoclasts, and conditioned medium derived from macrophages or osteoclasts induced activation of γδ T cells, as determined by the expression of the early activation marker CD69. TNFα was a major mediator of this stimulatory effect on γδ T cells. Consistent with this stimulatory effect, osteoclasts augmented proliferation of IL-2-stimulated γδ T cells and also supported the survival of unstimulated γδ and CD4(+) T cells, although these effects required co-culture with osteoclasts. Co-culture with osteoclasts also increased the proportion of γδ T cells producing IFNγ, but did not modulate IFNγ or IL-17 production by CD4(+) T cells. We provide new insights into the in vitro interactions between human γδ T cells and osteoclasts/macrophages, and demonstrate that osteoclasts or their precursors are capable of influencing γδ T function both via the release of soluble factors and also through direct cell-cell interactions.

Suppression of proteoglycan-induced autoimmune arthritis by myeloid-derived suppressor cells generated in vitro from murine bone marrow

Background

Myeloid-derived suppressor cells (MDSCs) are innate immune cells capable of suppressing T-cell responses. We previously reported the presence of MDSCs with a granulocytic phenotype in the synovial fluid (SF) of mice with proteoglycan (PG)-induced arthritis (PGIA), a T cell-dependent autoimmune model of rheumatoid arthritis (RA). However, the limited amount of SF-MDSCs precluded investigations into their therapeutic potential. The goals of this study were to develop an in vitro method for generating MDSCs similar to those found in SF and to reveal the therapeutic effect of such cells in PGIA.

Methods

Murine bone marrow (BM) cells were cultured for 3 days in the presence of granulocyte macrophage colony-stimulating factor (GM-CSF), interleukin-6 (IL-6), and granulocyte colony-stimulating factor (G-CSF). The phenotype of cultured cells was analyzed using flow cytometry, microscopy, and biochemical methods. The suppressor activity of BM-MDSCs was tested upon co-culture with activated T cells. To investigate the therapeutic potential of BM-MDSCs, the cells were injected into SCID mice at the early stage of adoptively transferred PGIA, and their effects on the clinical course of arthritis and PG-specific immune responses were determined.

Results

BM cells cultured in the presence of GM-CSF, IL-6, and G-CSF became enriched in MDSC-like cells that showed greater phenotypic heterogeneity than MDSCs present in SF. BM-MDSCs profoundly inhibited both antigen-specific and polyclonal T-cell proliferation primarily via production of nitric oxide. Injection of BM-MDSCs into mice with PGIA ameliorated arthritis and reduced PG-specific T-cell responses and serum antibody levels.

Conclusions

Our in vitro enrichment strategy provides a SF-like, but controlled microenvironment for converting BM myeloid precursors into MDSCs that potently suppress both T-cell responses and the progression of arthritis in a mouse model of RA. Our results also suggest that enrichment of BM in MDSCs could improve the therapeutic efficacy of BM transplantation in RA.

Identification of myeloid-derived suppressor cells in the synovial fluid of patients with rheumatoid arthritis: a pilot study

Background

Myeloid-derived suppressor cells (MDSCs) are a heterogeneous population of innate immune cells with a granulocyte-like or monocyte-like phenotype and a unique ability to suppress T-cell responses. MDSCs have been shown to accumulate in cancer patients, but recent studies suggest that these cells are also present in humans and animals suffering from autoimmune diseases. We previously identified MDSCs in the synovial fluid (SF) of mice with experimental autoimmune arthritis. The goal of the present study was to identify MDSCs in the SF of patients with rheumatoid arthritis (RA).

Methods

RA SF cells were studied by flow cytometry using antibodies to MDSC cell surface markers as well as by analysis of cell morphology. The suppressor activity of RA SF cells toward autologous peripheral blood T cells was determined ex vivo. We employed both antigen-nonspecific (anti-CD3/CD28 antibodies) and antigen-specific (allogeneic cells) induction systems to test the effects of RA SF cells on the proliferation of autologous T cells.

Results

SF from RA patients contained MDSC-like cells, the majority of which showed granulocyte (neutrophil)-like phenotype and morphology. RA SF cells significantly suppressed the proliferation of anti-CD3/CD28-stimulated autologous T cells upon co-culture. When compared side by side, RA SF cells had a more profound inhibitory effect on the alloantigen-induced than the anti-CD3/CD28-induced proliferation of autologous T cells.

Conclusion

MDSCs are present among RA SF cells that are commonly regarded as inflammatory neutrophils. Our results suggest that the presence of neutrophil-like MDSCs in the SF is likely beneficial, as these cells have the ability to limit the expansion of joint-infiltrating T cells in RA.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2474-15-281) contains supplementary material, which is available to authorized users.

Preclinical characterisation of the GM-CSF receptor as a therapeutic target in rheumatoid arthritis

Objective

Previous work has suggested that the granulocyte macrophage colony stimulating factor (GM-CSF)–GM-CSF receptor α axis (GM-CSFRα) may provide a new therapeutic target for the treatment of rheumatoid arthritis (RA). Therefore, we investigated the cellular expression of GM-CSFRα in RA synovial tissue and investigated the effects of anti-GM-CSFRα antibody treatment in vitro and in vivo in a preclinical model of RA.

Methods

We compared GM-CSFRα expression on macrophages positive for CD68 or CD163 on synovial biopsy samples from patients with RA or psoriatic arthritis (PsA) to disease controls. In addition, we studied the effects of CAM-3003, an anti-GM-CSFR antibody in a collagen induced arthritis model of RA in DBA/1 mice. The pharmacokinetic profile of CAM-3003 was studied in naïve CD1(ICR) mice (see online supplement) and used to interpret the results of the pharmacodynamic studies in BALB/c mice.

Results

GM-CSFRα was expressed by CD68 positive and CD163 positive macrophages in the synovium, and there was a significant increase in GM-CSFRα positive cells in patients in patients with RA as well as patients with PsA compared with patients with osteoarthritis and healthy controls. In the collagen induced arthritis model there was a dose dependent reduction of clinical arthritis scores and the number of F4/80 positive macrophages in the inflamed synovium after CAM-3003 treatment. In BALB/c mice CAM-3003 inhibited recombinant GM-CSF mediated margination of peripheral blood monocytes and neutrophils.

Conclusions

The findings support the ongoing development of therapies aimed at interfering with GM-CSF or its receptor in various forms of arthritis, such as RA and PsA.

Mechanisms, impact and management of pain in rheumatoid arthritis

People with rheumatoid arthritis (RA) identify pain as their most important symptom, one that often persists despite optimal control of inflammatory disease. RA pain arises from multiple mechanisms, involving inflammation, peripheral and central pain processing and, with disease progression, structural change within the joint. Consequently, RA pain has a wide range of characteristics-constant or intermittent, localized or widespread-and is often associated with psychological distress and fatigue. Dominant pain mechanisms in an individual are identified by critical evaluation of clinical symptoms and signs, and by laboratory and imaging tests. Understanding these mechanisms is essential for effective management, although evidence from preclinical models should be interpreted with caution. A range of pharmacological analgesic and immunomodulatory agents, psychological interventions and surgery may help manage RA pain. Pain contributes importantly to the clinical assessment of inflammatory disease activity, and noninflammatory components of RA pain should be considered when gauging eligibility for or response to biologic agents. Further randomized controlled trials are required to determine the optimal usage of analgesics in RA, and novel agents with greater efficacy and lower propensity for adverse events are urgently needed. Meanwhile, targeted use of existing treatments could reduce pain in people with RA.

TNFα, PDGF, and TGFβ synergistically induce synovial lining hyperplasia via inducible PI3Kδ

OBJECTIVES

To determine the mechanism underlying hypertrophic synovium in rheumatoid arthritis (RA).

METHODS

We examined micromass cultures of fibroblast-like synoviocytes (FLSs) stimulated with tumor necrosis factor α (TNFα), platelet-derived growth factor (PDGF), and/or transforming growth factor β (TGFβ). The hypertrophic architecture of the micromasses, expression of phosphoinositide 3 kinase (PI3K) isoforms, and persistent activation of PI3K-Akt pathways were investigated. FLSs transfected with siRNA were also examined in the micromass cultures.

RESULTS

The combination of TNFα, PDGF, and TGFβ (TPT condition) induced obvious hypertrophic architecture of the intimal lining layer in FLSs in micromass cultures, and was accompanied by upregulated expression of matrix metalloproteinase-3 (MMP3), Cadherin-11, and PI3Kδ. In monolayer FLSs, the TPT condition enhanced the expression of PI3Kδ and persistent activation of the PI3K-Akt pathway. Knockdown of PI3Kδ significantly inhibited the formation of the hypertrophic synovial lining in the TPT condition.

CONCLUSIONS

These results collectively indicate that inducible PI3Kδ plays a crucial role in persistent activation of PI3K-Akt in FLSs, and in the formation of a hypertrophic synovial lining. PI3Kδ may be an alternative treatment target for the regulation of proliferative synovium in RA.

Cytokines as biomarkers in rheumatoid arthritis

RA is a complex disease that develops as a series of events often referred to as disease continuum. RA would benefit from novel biomarker development for diagnosis where new biomarkers are still needed (even if progresses have been made with the inclusion of ACPA into the ACR/EULAR 2010 diagnostic criteria) and for prognostic notably in at risk of evolution patients with autoantibody-positive arthralgia. Risk biomarkers for rapid evolution or cardiovascular complications are also highly desirable. Monitoring biomarkers would be useful in predicting relapse. Finally, predictive biomarkers for therapy outcome would allow tailoring therapy to the individual. Increasing numbers of cytokines have been involved in RA pathology. Many have the potential as biomarkers in RA especially as their clinical utility is already established in other diseases and could be easily transferable to rheumatology. We will review the current knowledge's relation to cytokine used as biomarker in RA. However, given the complexity and heterogeneous nature of RA, it is unlikely that a single cytokine may provide sufficient discrimination; therefore multiple biomarker signatures may represent more realistic approach for the future of personalised medicine in RA.

Effects of IL-6 and IL-6 blockade on neutrophil function in vitro and in vivo

OBJECTIVES

Reports on the regulation of neutrophil function by IL-6 are often conflicting. Therapeutic inhibition of IL-6 in RA is associated with occasional neutropenia, but the mechanisms underlying this observation are poorly understood. This study investigated interactions between IL-6, the anti-IL-6 receptor agent tocilizumab (TCZ) and neutrophils in vitro and in vivo.

METHODS

Neutrophils were isolated from healthy controls and incubated in vitro with pharmacologically relevant concentrations of IL-6 or TCZ. Neutrophils were also isolated from RA patients, including a cohort following TCZ therapy. Apoptosis was measured by annexin V/propidium iodide (PI) flow cytometry; phagocytosis was measured by incubating apoptotic neutrophils with THP-1-derived macrophages; chemotaxis was measured using cell migration through hanging-cell inserts towards IL-8 and cell surface proteins, including adhesion molecules CD11b (αMβ2 integrin) and CD62L (L-selectin) were measured by flow cytometry.

RESULTS

IL-6 (10-100 ng/ml) did not affect the rate of neutrophil apoptosis, priming of the respiratory burst or adhesion molecule expression nor act as a neutrophil chemoattractant. However, IL-6 enhanced signal transducer and activator of transcription 3 (STAT3) activation and neutrophil migration towards IL-8. TCZ in vitro did not induce apoptosis or phagocytosis of neutrophils, nor did it have a significant effect upon apoptosis or cell surface molecule expression. Neutrophil functions in ex vivo neutrophils from RA patients receiving TCZ treatment were unaffected.

CONCLUSION

Therapeutic blockade of IL-6, while inducing a transient neutropenia, does not directly affect neutrophil functions associated with host defence. TCZ-associated neutropenia cannot be explained by direct induction of apoptosis by TCZ, induction of apoptosis following depletion of IL-6, nor increased phagocytosis of neutrophils.

MOR103, a human monoclonal antibody to granulocyte-macrophage colony-stimulating factor, in the treatment of patients with moderate rheumatoid arthritis: results of a phase Ib/IIa randomised, double-blind, placebo-controlled, dose-escalation trial

Objectives

To determine the safety, tolerability and signs of efficacy of MOR103, a human monoclonal antibody to granulocyte–macrophage colony-stimulating factor (GM-CSF), in patients with rheumatoid arthritis (RA).

Methods

Patients with active, moderate RA were enrolled in a randomised, multicentre, double-blind, placebo-controlled, dose-escalation trial of intravenous MOR103 (0.3, 1.0 or 1.5 mg/kg) once a week for 4 weeks, with follow-up to 16 weeks. The primary outcome was safety.

Results

Of the 96 randomised and treated subjects, 85 completed the trial (n=27, 24, 22 and 23 for pooled placebo and MOR103 0.3, 1.0 and 1.5 mg/kg, respectively). Treatment emergent adverse events (AEs) in the MOR103 groups were mild or moderate in intensity and generally reported at frequencies similar to those in the placebo group. The most common AE was nasopharyngitis. In two cases, AEs were classified as serious because of hospitalisation: paronychia in a placebo subject and pleurisy in a MOR103 0.3 mg/kg subject. Both patients recovered fully. In exploratory efficacy analyses, subjects in the MOR103 1.0 and 1.5 mg/kg groups showed significant improvements in Disease Activity Score-28 scores and joint counts and significantly higher European League Against Rheumatism response rates than subjects receiving placebo. MOR103 1.0 mg/kg was associated with the largest reductions in disease activity parameters.

Conclusions

MOR103 was well tolerated and showed preliminary evidence of efficacy in patients with active RA. The data support further investigation of this monoclonal antibody to GM-CSF in RA patients and potentially in those with other immune-mediated inflammatory diseases.

Trial registration number

NCT01023256

Plasma IL-6 levels correlate with clinical and ultrasound measures of arthritis in patients with systemic lupus erythematosus

OBJECTIVE

The objective of this paper is to elucidate the role of specific cytokines in lupus (SLE) arthritis.

METHODS

Fifty SLE and 40 RA patients had an ultrasound (US) scan of their hand as per standardized protocols. US scores were expressed per joint and as a total 'US activity' score, (sum of power Doppler (PD) and grey-scale synovial hypertrophy scores in all joints) and a total erosion score. SLE disease activity was assessed (BILAG and SELENA-SLEDAI). Plasma levels of IL-6, TNF-alpha and BLyS were measured using sandwich ELISA kits (Quantikine kits, R & D).

RESULTS

On the basis of the US results SLE patients were divided into three groups: erosive arthritis (n = 20), non-erosive arthritis (n = 18) and those with a normal US scan (n = 12). Across the SLE groups plasma IL-6 levels correlated with CRP (p < 0.001), hand deformity scores (p = 0.005), BILAG musculoskeletal score (p = 0.009), wrist PD score (p = 0.01), the presence of tenosynovitis (p = 0.008) and total US activity score (p < 0.001) (which remained constant when corrected for total BILAG score). Neither TNF-alpha nor BLyS levels correlated with US or clinical measures of lupus arthritis; however, TNF-alpha correlated with total BILAG score (p < 0.001).

CONCLUSION

This is the first study to examine levels of specific cytokines in a cohort of SLE patients stratified in terms of joint disease by US, where the most significant finding is that IL-6 levels correlated both with clinical and US measures of arthritis disease activity.

ACPA fine-specificity profiles in early rheumatoid arthritis patients do not correlate with clinical features at baseline or with disease progression

INTRODUCTION

Autoantibodies against citrullinated peptides/proteins (ACPA) are found in approximately 75% of the sera of patients with rheumatoid arthritis (RA). The RA-specific ACPA are frequently present prior to disease onset and their presence associates with a more erosive disease course. ACPA can therefore be used to aid the diagnosis and prognosis of RA. Recently, it became clear that ACPA are very heterogeneous, both in an individual patient and among different patients. The aim of this study was to investigate whether clinically meaningful ACPA profiles exist in early RA patients.

METHODS

Twenty citrullinated peptides and the corresponding non-citrullinated control peptides were immobilized on microarray sensor chips. Sera from 374 early arthritis patients were analyzed by surface plasmon resonance imaging (iSPR) of biomolecular interactions on the sensor chip.

RESULTS

Cluster analysis of the reactivities with the citrullinated peptides, after subtraction of the reactivities with the corresponding control peptides confirmed the heterogeneity of the ACPA response in RA and revealed 12 distinct ACPA profiles. The association of the 5 most frequent profiles with clinical features at diagnosis and during the disease course was examined, showing no statistically significant associations.

CONCLUSIONS

Compared to the detection of ACPA in RA sera by CCP-based assays, ACPA profiling in early arthritis patients did not reveal associations with disease activity and progression scores.

RNA-seq reveals activation of both common and cytokine-specific pathways following neutrophil priming

Neutrophils are central to the pathology of inflammatory diseases, where they can damage host tissue through release of reactive oxygen metabolites and proteases, and drive inflammation via secretion of cytokines and chemokines. Many cytokines, such as those generated during inflammation, can induce a similar “primed” phenotype in neutrophils, but it is unknown if different cytokines utilise common or cytokine-specific pathways to induce these functional changes. Here, we describe the transcriptomic changes induced in control human neutrophils during priming in vitro with pro-inflammatory cytokines (TNF-α and GM-CSF) using RNA-seq. Priming led to the rapid expression of a common set of transcripts for cytokines, chemokines and cell surface receptors (CXCL1, CXCL2, IL1A, IL1B, IL1RA, ICAM1). However, 580 genes were differentially regulated by TNF-α and GM-CSF treatment, and of these 58 were directly implicated in the control of apoptosis. While these two cytokines both delayed apoptosis, they induced changes in expression of different pro- and anti-apoptotic genes. Bioinformatics analysis predicted that these genes were regulated via differential activation of transcription factors by TNF-α and GM-CSF and these predictions were confirmed using functional assays: inhibition of NF-κB signalling abrogated the protective effect of TNF-α (but not that of GM-CSF) on neutrophil apoptosis, whereas inhibition of JAK/STAT signalling abrogated the anti-apoptotic effect of GM-CSF, but not that of TNF-α (p<0.05). These data provide the first characterisation of the human neutrophil transcriptome following GM-CSF and TNF-α priming, and demonstrate the utility of this approach to define functional changes in neutrophils following cytokine exposure. This may provide an important, new approach to define the molecular properties of neutrophils after in vivo activation during inflammation.

Cytokine measurements and possible interference from heterophilic antibodies--problems and solutions experienced with rheumatoid factor

Cytokines are important in the understanding of the immune process in health and disease and are valuable indicators in diagnostics. Measurements of cytokines are based on immunometric methods, and it is important to understand possible pitfalls in these methods to produce reliable cytokine data. This paper focuses on obtaining optimal measurements when applying enzyme-linked immunosorbent assay (ELISA) or multiplex immunoassays (MIA). Cytokines are measured in serum or plasma, as well as in various other body fluids, all containing a series of antibodies and the possibility of interference from these. Some antibodies, such as heterophilic and human anti-animal antibodies, are able to interfere with all immunoassays, but the immunometric techniques are most prone to serious interference from this source. Another type, rheumatoid factor (RF) is a composite of different autoimmune antibodies which can be present in both blood and synovial fluid. RF is present in some arthritic diseases as well as in some other medical conditions. When present, especially RF IgM is known to interfere with the immunometric measurements. A possible and affordable solution to diminish this interference is PEG precipitation, but other efficient, but more expensive, methods, such as precipitation using Protein L or commercially available blocking agents, are also available. Interference of RF is at present not tested in all cytokine assays, but degree of interference from RF, human anti-animal and heterophilic antibodies, as well as from other possible disease-specific antibodies, must always be considered when developing and applying new assays for cytokine measurements.

HLA-G may predict the disease course in patients with early rheumatoid arthritis

The current management of early rheumatoid arthritis (ERA) is to start an intensive treatment as soon as possible. To avoid under/overtreatment, it is important to identify reliable ERA evolution biomarkers. HLA-G molecules has been associated with rheumatoid arthritis, suggesting a role in disease regulation. HLA-G antigens are expressed as membrane bound and soluble isoforms (mHLA-G, sHLA-G) that act as ligand for immune-inhibitory receptors (ILT2, ILT4, KIR2DL4). Expression of HLA-G is influenced by a 14 bp insertion/deletion polymorphism in exon 8 of the gene, where the deletion is associated with mRNA stability. We analyzed 23 ERA patients during a 12 months follow-up disease treatment for sHLA-G, IL-1beta, IL-6, IL-10 and TNF-alpha levels in plasma samples by ELISA, mHLA-G and ILT2 expression on peripheral blood CD14 positive cells by flow cytometry and typed HLA-G 14 bp deletion/insertion polymorphism by Real-Time PCR. Disease status (DAS28), ultrasonography with power Doppler and laboratory data were checked. Cytokine levels confirmed the anti-inflammatory effect of the treatment. sHLA-G, mHLA-G and ILT2 expression inversely correlated with DAS28 disease scores. The frequency of 14 bp deletion allele increased in patients with disease remission. Based on these results, HLA-G may be a candidate biomarker to evaluate early prognosis and disease activity in ERA patients.

Disease-dependent local IL-10 production ameliorates collagen induced arthritis in mice

Rheumatoid arthritis (RA) is a chronic destructive autoimmune disease characterised by periods of flare and remission. Today’s treatment is based on continuous immunosuppression irrespective of the patient’s inflammatory status. When the disease is in remission the therapy is withdrawn but withdrawal attempts often results in inflammatory flares, and re-start of the therapy is commenced when the inflammation again is prominent which leads both to suffering and increased risk of tissue destruction. An attractive alternative treatment would provide a disease-regulated therapy that offers increased anti-inflammatory effect during flares and is inactive during periods of remission. To explore this concept we expressed the immunoregulatory cytokine interleukin (IL)-10 gene under the control of an inflammation dependent promoter in a mouse model of RA - collagen type II (CII) induced arthritis (CIA). Haematopoetic stem cells (HSCs) were transduced with lentiviral particles encoding the IL-10 gene (LNT-IL-10), or a green fluorescence protein (GFP) as control gene (LNT-GFP), driven by the inflammation-dependent IL-1/IL-6 promoter. Twelve weeks after transplantation of transduced HSCs into DBA/1 mice, CIA was induced. We found that LNT-IL-10 mice developed a reduced severity of arthritis compared to controls. The LNT-IL-10 mice exhibited both increased mRNA expression levels of IL-10 as well as increased amount of IL-10 produced by B cells and non-B APCs locally in the lymph nodes compared to controls. These findings were accompanied by increased mRNA expression of the IL-10 induced suppressor of cytokine signalling 1 (SOCS1) in lymph nodes and a decrease in the serum protein levels of IL-6. We also found a decrease in both frequency and number of B cells and serum levels of anti-CII antibodies. Thus, inflammation-dependent IL-10 therapy suppresses experimental autoimmune arthritis and is a promising candidate in the development of novel treatments for RA.