Serum adenosine deaminase may predict disease activity in rheumatoid arthritis

Pharmacological Aspects of Natural Quercetin in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease that can lead to severe joint damage, disability and mortality. Quercetin (QUE) is a natural flavonoid that is ubiquitous in fruits and vegetables. This article reviews the effect of QUE on articular and extra-articular manifestations of RA in vitro and in vivo. In general, for articular manifestations, QUE inhibited synovial membrane inflammation by reducing inflammatory cytokines and mediators, decreasing oxidative stress, inhibiting proliferation, migration and invasion, and promoting apoptosis of fibroblast-like synoviocytes (FLS), regulated autoimmune response through modulating Th17/Treg imbalance and Th17 cells differentiation, reducing autoantibodies levels and regulating ectonucleoside triphosphate diphosphohydrolase (E-NTPDase)/ectoadenosine deaminase (E-ADA) activities, reduced bony damage via lowering matrix metalloproteinase (MMP)-1, MMP-3, receptor activator of nuclear factor kappa B ligand (RANKL) expression and osteoclasts formation. For extra-articular manifestations, QUE could reverse the neurodegenerative processes of the enteric nervous system (ENS) and exhibited cytoprotective, genoprotective and hepatoprotective effects. In addition, we also summarize some contradictory experimental results and explore the possibility for these differences to form a sound basis for the clinical application of QUE for RA.

Potential therapeutic application of biophenols - plants secondary metabolites in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease showed that persistent inflammation in the joints, induces the cartilage destruction, bone erosion, and leukocyte infiltration in the synovium. RA mostly affects the joints of hands, feet, wrists, ankles, and knees. Each year, approximately 20-40 new cases are reported per lac population and the disease affects women more than men. The etiology of RA is still unknown, but many pathways have been identified as potential targets in its pathophysiology, including the PI3K/AKT signaling pathway, NF-κB signaling, Adenosine signaling, Wnt, SYK/BTK, and mTOR signaling pathways. Biophenol, plant secondary metabolite, is considered one of the most abundantly phytoconstituents to have potential anti-inflammatory effects associated with multiple pathways. These indicate that biophenols can be used for its protective effect on the development and symptoms of RA. The current review explores and discusses the role of different biophenols in the treatment of RA disease.

Quercetin mitigates rheumatoid arthritis by inhibiting adenosine deaminase in rats

Rheumatoid arthritis (RA) is a chronic inflammatory joint disease characterized by synovial proliferation and bone destruction. Adenosine deaminase (ADA) is a key inflammatory enzyme that increases joint stiffness and pain in RA. In this study, we evaluated the in-silico, and in vivo inhibitory effect of quercetin isolated from Egyptian Fenugreek on ADA enzyme activity. We also determined the combinatorial effect of quercetin on methotrexate mediated anti-inflammatory efficacy and toxicity. In-silico molecular docking was conducted and confirmed in an in vivo RA rat model. The results showed that the inhibition constant of quercetin on joint ADA by docking and in-vitro was 61.9 and 55.5 mM, respectively. Therefore, quercetin exhibits anti-inflammatory effect in a rat RA model as evidenced by reducing the specific activity of ADA in joint tissues, lower jaw volume, enhance body weight, downregulate ADA gene expression, reduce levels of RA cytokines interleukin-1^β, interleukin-6, tumor necrosis factor-α, also, rheumatoid factor, C-reactive protein, and anti-cyclic citrullinated peptide RA biomarker levels. These findings demonstrate that the purified quercetin has a promising anti-inflammatory effect against RA disease through its inhibitory effects on the ADA enzyme. Furthermore, isolated quercetin improved the anti-inflammatory efficacy of methotrexate, reduced its toxic effects by increasing antioxidant enzymes and reducing oxidative stress.

Adenosine Deaminase Gene Polymorphism and Baseline Serum Level of Adenosine Deaminase as a Biomarker of Response to Methotrexate in Rheumatoid Arthritis

BACKGROUND

Methotrexate (MTX) is the first-line therapy for rheumatoid arthritis (RA), but nearly 30% of RA patients do not respond to it. Methotrexate acts by enhancing the level of adenosine, which gets converted to inosine by the enzyme adenosine deaminase (ADA). We studied whether ADA gene polymorphism and serum levels of total ADA are associated with responsiveness to MTX.

METHODS

Two hundred seven disease-modifying antirheumatic drug-naive active RA patients (DAS28-ESR [Disease Activity Score-28 for rheumatoid arthritis with erythrocyte sedimentation rate] ≥3.2) satisfying the European League Against Rheumatism (EULAR)/American College of Rheumatology 2010 criteria were enrolled. Genotyping was done in all patients, and in a subset (n = 59), blood was collected at baseline and at 2 months of MTX treatment for serum total ADA estimation by ELISA. Response at 4 months was assessed by EULAR criteria, and patients were classified as responders or nonresponders. The correlation of baseline clinical parameters, ADA gene polymorphism, and serum total ADA levels with EULAR response was sought.

RESULTS

After 4 months of MTX monotherapy, 172 patients (83.1%) were classified as responders and 35 (16.9%) as nonresponders. Except DAS28-ESR (6.1 [5.43-6.84] in responders vs 5.6 [4.77-6.21] in nonresponders, p = 0.02), other baseline parameters (age, disease duration, ESR, and C-reactive protein level) were similar between responders and nonresponders. Single nucleotide polymorphisms in ADA gene, baseline serum ADA levels (10.52 ± 5.37 ng/mL in responders vs 12.28 ± 5.14 ng/mL in nonresponders), or change in ADA levels after 2 months of MTX therapy did not show any association with MTX response (p = 0.73, p = 0.34, p = 0.55, respectively). Adenosine deaminase genotype did not affect the blood ADA level.

CONCLUSIONS

No association was seen between ADA single nucleotide polymorphism rs244076 as well as serum ADA level and response to MTX therapy.

The association between serum adenosine deaminase levels and Graves' disease

BACKGROUND

Adenosine deaminase (ADA) is essential for the differentiation and maturation of lymphocytes, while lymphocytes infiltration in thyroid tissue is a vital pathological feature of Graves' disease (GD). The aim of the present study was to compare the concentration of ADA between healthy controls (HC) and patients with GD, and evaluate the association between ADA and GD.

METHODS

A total of 112 GD patients and 77 matched HC were enrolled in this study. Each participant was examined for thyroid hormones and autoantibodies, ADA concentration, and thyroid ultrasonography.

RESULTS

Serum ADA levels in GD patients were significantly higher than that in HC subgroup (P < 0.001). In GD patients, serum ADA levels were positively associated with serum-free triiodothyronine (FT3), free thyroxine (FT4), thyroid peroxidase antibody (TPOAb), thyroid-stimulating hormone receptor antibody (TRAb) levels, and total thyroid gland volume (thyroid VolT) and negatively associated with serum thyroid-stimulating hormone receptor (TSH) levels (all P < 0.05). There were no similar correlations in the HC subgroup. Multiple linear regression analysis suggested that serum TSH, FT3, and ADA levels played an important role in serum TRAb levels.

CONCLUSIONS

Our results demonstrated that serum ADA levels were closely associated with GD.

Adenosine deaminase modulates metabolic remodeling and orchestrates joint destruction in rheumatoid arthritis

Rheumatoid Arthritis (RA) is a chronic autoimmune disease associated with inflammation and joint remodeling. Adenosine deaminase (ADA), a risk factor in RA, degrades adenosine, an anti-inflammatory molecule, resulting in an inflammatory bias. We present an integrative analysis of clinical data, cytokines, serum metabolomics in RA patients and mechanistic studies on ADA-mediated effects on in vitro cell culture models. ADA activity differentiated patients into low and high ADA sets. The levels of the cytokines TNFα, IFNγ, IL-10, TGFβ and sRANKL were elevated in RA and more pronounced in high ADA sets. Serum metabolomic analysis shows altered metabolic pathways in RA which were distinct between low and high ADA sets. Comparative analysis with previous studies shows similar pathways are modulated by DMARDs and biologics. Random forest analysis distinguished RA from control by methyl-histidine and hydroxyisocaproic acid, while hexose-phosphate and fructose-6-phosphate distinguished high ADA from low ADA. The deregulated metabolic pathways of High ADA datasets significantly overlapped with high ADA expressing PBMCs GEO transcriptomics dataset. ADA induced the death of chondrocytes, synoviocyte proliferation, both inflammation in macrophages and their differentiation into osteoclasts and impaired differentiation of mesenchymal stem cells to osteoblasts and mineralization. PBMCs expressing elevated ADA had increased expression of cytokines and P2 receptors compared to synovial macrophages which has low expression of ADA. Our data demonstrates increased cytokine levels and distinct metabolic signatures of RA based on the ADA activity, suggests an important role for ADA in the pathophysiology of RA joints and as a potential marker and therapeutic target in RA patients.

Serum Adenosine Deaminase as a Useful Marker to Estimate Coronary Artery Calcification in Type 2 Diabetes Mellitus Patients

We investigated the association between serum adenosine deaminase and coronary artery calcification (CAC) in type 2 diabetes mellitus (T2DM) patients. The cross-sectional study included 459 patients with T2DM, the clinical and laboratory tests were performed, and all T2DM patients were separated into the 3 groups based on the tertile of serum adenosine deaminase levels. In the baseline data, the CAC score had statistically significant differences between the 3 groups (p < 0.001). Serum adenosine deaminase levels were positively correlated with CAC score in T2DM patients (r = 0.355, p < 0.001). The results of multiple linear regression analysis showed that serum adenosine deaminase was independent positively correlated with CAC score in T2DM patients (r = 0.255, p < 0.001). Receiver-operating characteristic curve analysis showed that area under curve was 0.750 to identify T2DM patients with CAC. Serum adenosine deaminase levels are correlated with CAC scores in T2DM patients, clinically, serum adenosine deaminase should be considered as an underlying marker to determine the severity of atherosclerosis in T2DM patients.

Activities of Serum Adenosine Deaminase and its Isoenzymes in Patients with Systemic Lupus Erythematosus, Rheumatoid Arthritis, Ankylosing Spondylitis and Myasthenia Gravis

Objective The aim of this study was to evaluate the changes and diagnostic value of serum ADA activity in autoimmune diseases, including systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), ankylosing spondylitis (AS), and myasthenia gravis (MG).

Methods Serum ADA activity, including total ADA (tADA) and its isoenzymes (ADA1 and ADA2), was determined in patients with different autoimmune diseases (144 RA, 114 SLE, 55 AS, 68 MG). The changes in serum ADA activity in patients were analysed. A receiver operating characteristic (ROC) curve analysis was applied to evaluate the diagnostic performance of serum ADA activity.

Results Compared with healthy controls, the serum tADA activity in SLE patients was significantly increased (p<0.001), while the serum tADA activity in patients with RA, AS and MG did not change (p>0.05). The ROC analysis showed that the optimal cut-off value of serum tADA activity for SLE diagnosis was 10.5 U/L (79.8% specificity and 74.6% sensitivity; likelihood ratio (LR): 3.693; p<0.001). Moreover, our results showed that there were no significant changes of ADA1 and ADA2 activity in RA, AS and MG patients, while the serum ADA2 activity was significantly increased in SLE patients. The ROC analysis showed that ADA2 activity could be used in diagnosing SLE with 75.4% specificity and 78.1% sensitivity (LR: 3.175). Based on the ROC curve analysis, serum tADA activity (79.8% specificity and 74.6% sensitivity; likelihood ratio (LR): 3.693) and ADA2 activity (75.4% specificity and 78.1% sensitivity; LR: 3.175) are unlikely to be used in diagnosing SLE. Furthermore, there was a positive correlation between tADA activity and SLE disease activity (r=0.303, p=0.010). Notably, serum tADA activity in SLE patients with arthritis was higher than in patients without arthritis (p=0.005), which suggests that tADA activity might be related to lupus arthritis.

Conclusion These findings suggest that serum tADA and ADA2 activity might play an important role in SLE progression.

ATP and adenosine: Role in the immunopathogenesis of rheumatoid arthritis

Rheumatoid arthritis (RA) is a classic inflammatory autoimmune disease. Local joint destruction and extra-articular manifestations of RA deeply compromise the life quality of the affected patients. RA immunopathogenesis depends on continuous immunogenic activation in which the purinergic system participates. The purinergic system comprises the signaling and metabolism of purines such as adenosine triphosphate (ATP) and adenosine. ATP signaling is involved in the activation and maintenance of the inflammatory state of RA through the activation of P2X7 and the production of cytokines, which orchestrate the pathogenesis of RA. The breakdown of ATP through the CD39/CD73 axis produces adenosine, which mostly inhibits the inflammatory process through activation of specific P1 receptors. Adenosine is hydrolyzed by adenosine deaminase (ADA) that interacts with other molecules playing additional roles in this disease. This review explores the release, metabolism, and the effects of binding of ATP and adenosine to their respective receptors in the context of RA, as well as their potential use as biomarkers and therapeutic targets.

Adenosine Deaminase Activity and HLA-DRB as Diagnostic Markers for Rheumatoid Arthritis

BACKGROUND

Rheumatoid Arthritis (RA) is a chronic multi systemic disorder with the unclarified ethiopathology. Although several markers have been presented for recognition of RA, but none of them has been specific. New markers such as HLA typing and activity of Adenosine Deaminase (ADA) isoenzymes could be useful and specific.

OBJECTIVE

The aim of this study is to evaluate the pattern of ADA isoenzymes activity and HLA typing in both RA patients and healthy cases.

METHODS

Blood samples were collected from 55 RA patients and 60 healthy subjects, over a period of 6 months. Levels of C-reactive Protein (CRP), Rheumatoid Factor (RF) and ADA (ADA1, ADA2, total ADA) were measured using AVITEX kit and HITACHI Auto Analyzer. In addition, HLA-DRB1*01,*04 and *10 was detected using PCR-SSP.

RESULTS

ADA activity, particularly ADA2 level, was significantly higher among RA group (Pv <0.05). The concentrations of tADA in patients with RF and CRP positive were significantly higher (Pv <0.05). The allele prevalence of DRB1*01 was significantly higher in RA patients (13.1%) compared with control group (5.5%, respectively) (P <0.05, Bonferroni adjustment P<0.003). Calculated sensitivity and specificity for diagnostic tests in this study are listed as: CRP (75%), RF (80%), ADA (84%) and RF (90%), ADA (83%), CRP (72%), respectively.

CONCLUSION

Increased tADA level and the frequency of DRB1*10 and *01 caused susceptibility to RA.

Salivary adiponectin, but not adenosine deaminase, correlates with clinical signs in women with Sjögren's syndrome: a pilot study

OBJECTIVES

To evaluate salivary adiponectin and adenosine deaminase (ADA) in women suffering from Sjögren's syndrome (SS).

METHODS

Salivary adiponectin and ADA were measured in patients with SS (n = 17) and compared to their values in healthy controls (n = 13) and patients suffering from drug-induced xerostomia (non-SS sicca group; n = 19). A clinical history was made for each patient, patients were examined clinically, and xerostomia inventory (XI) was performed.

RESULTS

Salivary adiponectin corrected by total protein was higher in patients with SS than in healthy individuals (P < 0.05) or patients with non-SS sicca (P < 0.01) and correlated with XI (r = 0.555; P < 0.05). Salivary ADA was higher in patients with SS and non-SS sicca compared to controls (P < 0.05 in both cases).

CONCLUSION

The results of the present study indicate that adiponectin and ADA are increased in the saliva of patients with SS.

CLINICAL RELEVANCE

Salivary adiponectin corrected by total protein can be a potential biomarker of SS.

TRIAL REGISTRATION

NCT03156569.

Mechanism of action of methotrexate in rheumatoid arthritis, and the search for biomarkers

The treatment and outcomes of patients with rheumatoid arthritis (RA) have been transformed over the past two decades. Low disease activity and remission are now frequently achieved, and this success is largely the result of the evolution of treatment paradigms and the introduction of new therapeutic agents. Despite the rapid pace of change, the most commonly used drug in RA remains methotrexate, which is considered the anchor drug for this condition. In this Review, we describe the known pharmacokinetic properties and putative mechanisms of action of methotrexate. Consideration of the pharmacodynamic perspective could inform the development of biomarkers of responsiveness to methotrexate, enabling therapy to be targeted to specific groups of patients. Such biomarkers could revolutionize the management of RA.

Serum Adenosine Deaminase as Inflammatory Marker in Rheumatoid Arthritis

BACKGROUND

Rheumatoid arthritis (RA) is a prototypical inflammatory joint disease. The degree of inflammation is reflected in the extent of joint damage, which further has influence on the quality of life of patients with RA, including risk of atherosclerosis. Hence, besides clinical indices, estimation of degree of inflammation using biochemical markers helps in effecting optimum treatment strategies. C-reactive protein (CRP) is established as an inflammatory marker in patients with RA. Adenosine deaminase (ADA), an enzyme of purine metabolism is considered as a marker of cell mediated immunity and has also been suggested as a marker of inflammatory process in RA. The present study attempts to study the efficacy of serum ADA activity as an inflammatory marker in RA.

MATERIALS AND METHODS

Forty six RA patients and forty six age and sex matched healthy controls were included in the study. ADA activity and high sensitivity C-reactive protein (hsCRP) levels in serum were measured in all the subjects. Statistical analyses were done using Medcalc statistical software version 12.2.2.

RESULTS

ADA activity and hsCRP levels were increased in RA patients compared to controls (p<0.0001 and 0.0001 respectively). Significant positive correlation was obtained between hsCRP and ADA in patients (r=0.316, p=0.033). Receiver operating characteristic (ROC) curve analysis revealed statistically significant area under curve (AUC) for ADA that is comparable to that obtained for hsCRP (0.776, p<0.0001 for ADA, 0.726, p<0.0001 for hsCRP). Similar diagnostic utility was obtained with ROC generated cut-off value of 25.3 IU/L (82.6% sensitivity and 65.2% specificity) and with control mean value of 23.48 IU/L (86.96% sensitivity and 54.35% specificity) for ADA.

CONCLUSION

Findings of the present study indicate the importance of ADA as a marker of inflammation. Considering the higher sensitivity obtained, we propose control mean (23.48 IU/L) as a cut-off for serum ADA activity as an inflammatory marker. Owing to the simplicity and also the cost effectiveness of ADA assay, ADA may be recommended as a marker of inflammation in patients with RA. However, further larger and well controlled studies are needed to establish its role as inflammatory marker.

No association between serum adenosine deaminase activity and disease activity in Crohn's disease

BACKGROUND

Adenosine deaminase activity is proposed as a marker of inflammation in some inflammatory conditions.

AIMS

To investigate the association of serum adenosine deaminase activity and disease activity in Crohn's disease patients.

METHODS

In a cross-sectional study, 30 consecutive known cases of Crohn's disease (15 with active disease and 15 in remission) referring to a university hospital in Tehran (Iran) and 15 age- and gender-matched healthy controls were studied. Disease activity was assessed using the Crohn's disease activity index (cutoff >150). Total serum adenosine deaminase activity, C-reactive protein, erythrocyte sedimentation rate, and fecal calprotectin were evaluated in patients. Serum adenosine deaminase activity was measured in controls.

RESULTS

Mean age of the patients was 36.8 ± 12.6 years, and 56.7 % were male. Serum adenosine deaminase activity in patients with active disease, patients in remission, and controls was 12.3 ± 5.9, 14.6 ± 6.2, and 11.9 ± 6.4 U/L, respectively (P = 0.458). Compared with patients in remission, those with active disease had higher erythrocyte sedimentation rate (40.4 ± 30.6 vs. 16.9 ± 16.0 mm/h, P = 0.014) and higher frequency of positive C-reactive protein (66.6 vs. 13.3 %, P = 0.004) and positive fecal calprotectin tests (86.6 vs. 33.3 %, P = 0.004). Serum adenosine deaminase activity was not correlated with erythrocyte sedimentation rate (r = 0.05, P = 0.761) and was not different between patients with positive and negative C-reactive protein (12.2 ± 5.4 vs. 14.2 ± 6.5 U/L, P = 0.393) and fecal calprotectin tests (11.7 ± 5.3 vs. 16.0 ± 6.5 U/L, P = 0.063).

CONCLUSIONS

In patients with Crohn's disease, serum adenosine deaminase activity is not associated with clinical disease activity or with other inflammation markers and cannot be suggested as an inflammation marker.

Serum Adenosine Deaminase Level is High But Not Related with Disease Activity Parameters in Patients with Rheumatoid Arthritis

Serum adenosine deaminase (ADA) has been previously proposed to predict disease activity in patients with rheumatoid arthritis (RA). The aim of this study was to investigate the level of serum ADA, and the relationship between ADA and disease activity markers, in a group of patients with RA.

A hundred and 10 patients with a diagnosis of RA were recruited from outpatient clinic of Rheumatology Unit. Demographic properties comprising age, gender, disease duration and drugs were recorded. Disease activity based on disease activity score (DAS)28-erythrocyte sedimentation rate (ESR) and DAS28- C reactive protein (CRP,) ESR, CRP levels, as well as pain by visual analog scale and rheumatoid factor (RF) were recorded. Serum ADA levels (IU/L) were determined in all RA patients and in 55 age and sex similar healthy control subjects.

Ninety-six female and 14 male RA patients with a mean age of 54.32±11.51, and with a mean disease duration of 11.5±9.13 years were included to the study. The control group comprised of 48 female and 7 male healthy subjects. 35.5% of the patients were on methotrexate (MTX) and 64.5% of patients were on combined DMARDs or combined MTX and anti-TNF therapies. The mean serum ADA level was statistically higher in RA patients than in control subjects (27.01±10.6 IU/L vs 21.8 ±9.9 IU/L). The mean values of ESR (23.2±14.8 mm/h), CRP (1.71±1.11mg/dL), pain by VAS (37.2±27.1), DAS28-ESR (2.72±0.77), DAS28 CRP (1.37±0.5) were not correlated with ADA levels (p>0.05).

Our results have shown that serum ADA levels are higher in RA patients than in controls but were not related with any of the disease activity markers. We conclude that ADA in the serum may not be a reliable biochemical marker to predict disease activity in patients with RA.

Serum adenosine deaminase in patients with rheumatoid arthritis treated with methotrexate

Objective:

Recently, adenosine deaminase (ADA) is introduced as helpful marker in diagnosis, prognosis, and monitoring of treatment in rheumatoid arthritis (RA). The aim of this study was to determine the efficacy of the serum ADA in diagnosis, prognosis, and monitoring of treatment with methotrexate (MTX) in RA.

Methods:

This was a self-controlled clinical trial conducted in university hospitals of Isfahan, Iran. The serum level of ADA, erythrocyte sedimentation rate (ESR), and rheumatoid factor (RF) were measured for 70 patients with active RA (Disease Activity Score-28 [DAS28] > 3/2). After three months of MTX treatment and disease remission (DAS28 < 2.6) these markers were measured again. ANCOVA multiregression and paired t-test were used to compare and evaluate the mean level and correlation of ADA, ESR, IgM-RF, and DAS before and after RA remission.

Findings:

The mean value for ADA activity was significantly higher than the normal one compared with other studies. Significant decreases were seen in values of ADA, ESR, RF, visual analogue scale (VAS), and DAS after remission. Also, the correlation coefficient between the values of ADA with ESR and DAS were statistically significant in baseline. Moreover, the statistically significant correlation between ADA and ESR, VAS, and DAS were seen after remission. No correlation was found in the case of the dosage of MTX with the value of ADA.

Conclusion:

It was concluded that ADA may be considered useful as a marker in diagnosis, prognosis, and monitoring of treatment with Methotrexate in RA.

Evaluation of circulating levels of inflammatory and bone formation markers in axial spondyloarthritis

Studies have demonstrated the important role of bone remodelling and osteoimmunology in the progression of inflammatory lesions in axial spondyloarthritis (SpA) disease. This study was conducted to evaluate the inflammatory response by analysis of the serum levels of pro-inflammatory and new bone formation markers in patients with axial SpA who were treated or not treated with anti-tumour necrosis factor-α (anti-TNF-α) or non-steroidal drugs (NSAIDs) and to identify whether these drugs modify the activity and severity of the disease. The serum levels of myeloperoxidase (MPO), adenosine deaminase (ADA), nitric oxide metabolites (NOx), bone alkaline phosphatase (BAP), Dickkopf-1 (DKK-1), and osteoprotegerin (OP) were measured in 52 SpA patients who were treated or not with anti-TNF-α or NSAIDs and in 26 healthy controls using colourimetric and enzyme immunoassay tests. The activity and the severity of illness in patients with SpA were assessed using questionnaires (Bath Ankylosing Spondylitis Metrology Index (BASMI), Bath Ankylosing Spondylitis Functional Index (BASFI), and Bath Ankylosing Spondylitis Disease Activity Index (BASDAI)). A significant difference between the controls and the patients without medication was observed in relation to NOx, BAP, and OP (p<0.01). When the patients were compared with regard to their treatment, there were no clinically significant differences between the groups (p>0.05). In conclusion, The NOx, BAP, and OP are emerging as important inflammatory pathways in axial SpA. Also the anti-TNF-α or non-steroidal drugs reduce the inflammation and destructions, however these treatments do not modify the serum levels of these biomarkers.

Purinergic signalling in the musculoskeletal system

It is now widely recognised that extracellular nucleotides, signalling via purinergic receptors, participate in numerous biological processes in most tissues. It has become evident that extracellular nucleotides have significant regulatory effects in the musculoskeletal system. In early development, ATP released from motor nerves along with acetylcholine acts as a cotransmitter in neuromuscular transmission; in mature animals, ATP functions as a neuromodulator. Purinergic receptors expressed by skeletal muscle and satellite cells play important pathophysiological roles in their development or repair. In many cell types, expression of purinergic receptors is often dependent on differentiation. For example, sequential expression of P2X5, P2Y1 and P2X2 receptors occurs during muscle regeneration in the mdx model of muscular dystrophy. In bone and cartilage cells, the functional effects of purinergic signalling appear to be largely negative. ATP stimulates the formation and activation of osteoclasts, the bone-destroying cells. Another role appears to be as a potent local inhibitor of mineralisation. In osteoblasts, the bone-forming cells, ATP acts via P2 receptors to limit bone mineralisation by inhibiting alkaline phosphatase expression and activity. Extracellular ATP additionally exerts significant effects on mineralisation via its hydrolysis product, pyrophosphate. Evidence now suggests that purinergic signalling is potentially important in several bone and joint disorders including osteoporosis, rheumatoid arthritis and cancers. Strategies for future musculoskeletal therapies might involve modulation of purinergic receptor function or of the ecto-nucleotidases responsible for ATP breakdown or ATP transport inhibitors.

Serum levels of calreticulin in correlation with disease activity in patients with rheumatoid arthritis

OBJECTIVE

The aim of our study was to investigate the contribution of serum calreticulin (CRT) in the assessment of disease activity in rheumatoid arthritis (RA).

METHODS

Serum CRT levels were measured by ELISA in 70 patients with established RA, 30 systemic lupus erythematosus (SLE), 25 other autoimmune diseases, 20 osteoarthritis (OA), and 35 of healthy controls (HC). Correlations of CRT serum levels with disease activity [Disease Activity Score for 28 joints (DAS28)], erythrocyte sedimentation rate(ESR) and C-reactive protein (CRP) were assessed. Serum CRT levels were also detected in RA patients whose RF, anti-CCP and anti- MCV antibodies were positive and negative.

RESULTS

Serum CRT levels in RA patients (4.817 ± 2.425 ng/ml) was significantly higher (P <0.05) compared with those in the serum of OA (3.574 ± 0.942 ng/ml), SLE (4.013 ± 1.536 ng/ml), other autoimmune diseases (3.882 ± 0.837 ng/ml) and HC (3.726 ± 0.627 ng/ml). Significant positive correlation of CRT with DAS28, ESR and CRP was found in RA patients. Furthermore, RA patients whose anti-CCP and anti-MCV antibodies were positive had higher levels of CRT (P < 0.01).

CONCLUSION

Serum CRT levels were increased in patients with RA compared with those controls. Moreover, a significant correlation was observed between serum CRT levels and disease activity in RA. It might be used as a potential biomarker for clinical diagnosis and provide additional information regarding disease activity along with the traditional indices such as ESR and CRP.

Serum anti-cyclic citrullinated peptide antibodies may predict disease activity in rheumatoid arthritis

To define the relationship between serum anti-cyclic citrullinated peptide antibodies (anti-CCP) and disease activity, and to construct a new disease activity index by using anti-CCP in rheumatoid arthritis (RA). One hundred and five RA patients were included. Disease activity based on DAS28-ESR and serum anti-CCP was measured. There was correlation between serum anti-CCP and DAS28-ESR. (R (2) = 0.71, P value < 0.01). New disease activity index was developed by replacing anti-CCP with ESR in DAS28-ESR. There was correlation between new model and DAS28-ESR. (R (2) = 0.91, P value < 0.01) The new composite index best cut-off values corresponding to DAS28-ESR values of 2.6, 3.2, and 5.1 were 3.21, 3.38, and 4.74, respectively. There was agreement between new model and DAS28-ESR for determination of patients in different disease activity categories. (Kappa = 0.71, P value < 0.01). The new disease activity index that applies serum anti-CCP may predict disease activity in RA.

A2A and A3 adenosine receptor expression in rheumatoid arthritis: upregulation, inverse correlation with disease activity score and suppression of inflammatory cytokine and metalloproteinase release

INTRODUCTION

The reduction of the inflammatory status represents one of the most important targets in rheumatoid arthritis (RA). A central role of A2A and A3 adenosine receptors (ARs) in mechanisms of inflammation has been reported in different pathologies. The primary aim of this study was to investigate the A2A and A3ARs and their involvement in RA progression measured by Disease Activity Score in 28 or 44 joints (DAS28 or DAS).

METHODS

ARs were analyzed by saturation binding assays, mRNA and Western blotting analysis in lymphocytes from early and established RA patients. The effect of A2A and A3AR agonists in nuclear factor kB (NF-kB) pathway was evaluated. Tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β) and interleukin-6 (IL-6) release was carried out by A2A and A3AR activation. AR pharmacological regulation in matrix metalloproteinase-1 (MMP-1) and metalloproteinase-3 (MMP-3) release was also studied.

RESULTS

In lymphocytes obtained from RA patients, A2A and A3ARs were up-regulated if compared with healthy controls. A2A and A3AR activation inhibited the NF-kB pathway and diminished inflammatory cytokines such as TNF-α, IL-1β and IL-6. A2A and A3AR agonists mediated a reduction of MMP-1 and MMP-3 release. A2A and A3AR density inversely correlated with DAS28 and DAS suggesting a direct role of the endogenous activation of these receptors in the control of RA joint inflammation.

CONCLUSIONS

Taken together these data demonstrate that the inflammatory and clinical responses in RA are regulated by A2A and A3ARs and support the use of A2A and/or A3AR agonists as novel and effective pharmacological treatment in RA patients.