Role of Advanced Glycation End Products as New Biomarkers in Systemic Lupus Erythematosus

Advanced glycation end-products (AGEs) may play a relevant role as inducers in the chronic inflammatory pathway present in immune-mediated diseases, such as systemic lupus erythematosus (SLE). AGEs concentrations have been associated, with discrepant results to date, with some parameters such as disease activity or accrual damage, suggesting their potential usefulness as biomarkers of the disease. Our objectives are to confirm differences in AGEs levels measured by cutaneous autofluorescence between SLE patients and healthy controls (HC) and to study their correlation with various disease parameters. Cross-sectional study, where AGEs levels were measured by skin autofluorescence, and SLE patients' data were compared with those of sex- and age-matched HC in a 1:3 proportion through a multiple linear regression model. Associations of AGEs levels with demographic and clinical data were analyzed through ANOVA tests. Both analyses were adjusted for confounders. AGEs levels in SLE patients were significantly higher than in HC (p < 0.001). We found statistically significant positive associations with SLE disease activity index (SLEDAI) and damage index (SDI), physician and patient global assessment, C-reactive protein, leukocyturia, complement C4, IL-6 and oral ulcers. We also found a negative statistically significant association with current positivity of anti-nuclear and anti-Ro60 antibodies. AGEs seem to have a contribution in LES pathophysiology, being associated with activity and damage and having a role as a new management and prognosis biomarker in this disease. The association with specific antibodies and disease manifestations may indicate a specific clinical phenotype related to higher or lower AGEs levels.

AB0498 CONCENTRATIONS OF ADVANCED GLYCATION END PRODUCTS (AGEs) CORRELATE WITH INDEXES OF ACTIVITY AND DAMAGE ACCRUAL IN PATIENTS WITH SYSTEMIC LUPUS ERYTHEMATOSUS (SLE)

Background

It has been postulated that AGES could have a relevant role as inducers in the chronic inflammatory pathway present in various diseases1; among them, in immune-mediated diseases such as SLE, as well as that its concentration could be related to some parameters of the disease such as activity 2 or accumulated damage 3, showing studies discrepant results to date.

Objectives

To describe correlations between the concentrations of AGEs measured by cutaneous autofluorescence and various parameters related to the disease in a population of SLE patients.

Methods

AGE concentrations were measured by skin autofluorescence (Age Reader Mu Connect from Diagnoptics Technologies BV) in 66 SLE Caucasian patients and correlations with demographic and clinical data were analyzed, after adjusting for age, smoking and corticosteroids as possible confounding factors, according to previous data. Previous validation studies have shown that skin autofluorescence is strongly related to AGE levels in skin biopsies4. The indices were analyzed both as quantitative and categorized variables according to previously established categories or to medians/tertiles/quartiles depending on the distribution of the variable in our population.

Results

Table 1 shows some descriptive characteristics of our cohort. There were clinically and statistically significant differences in the values of AGEs according to the patient’s SLEDAI and SLICC. Specifically, it was observed that AGEs’ values in the population with severe activity according to SLEDAI was 0.61 (95% CI 0.85-2.046; p=0.045) points > than in those in remission (p=0.045); as well as AGEs‘ values in patients with SLICC ≥1 was 1.23 (95% CI 0.49-1.98; p=0.030) points > than in the group without cumulative damage. In all the models, the values of AGEs increased significantly with age, smoking and current treatment with corticosteroids, except for the model including the SLICC variable. Interactions in said model were explored, and it was observed that the concentration of AGES depended on the interaction between the value of SLICC and the intake of corticosteroids, so that differences were only observed between SLICC groups in those who took corticosteroids.

Table 1.

Descriptive characteristics of the cohort. c: categorized.

AverageSD%Age5415BMI25.364.68SmokerNo68.2Yes31.8AGEs2.60.7Disease duration (years)1611DAS282.221.16cDAS28remission71.2low9.1moderate15.2high4.5SLEDAI54cSLEDAIremission21.2low16.7moderate51.5high10.6SLICC11cSLICC00.0148.5>130.3321.2FACIT Fatigue Scale1810Patient global assessment (PGA)3.02.4cPGA0-131.82-328.8>339.4Physician global assessment1.71.3cPhysician global assessment0-147.0>153.0Visual Analogue Scale (VAS)3.13.1cVAS034.81-430.3>434.8Health Assessment Questionnaire (HAQ)0.5270.551cHAQ033.30-0.7536.4>0.7530.3CorticoidsYes27.3No72.7

Conclusion

A correlation with elevated values of AGEs was observed in those SLE patients with higher scores in the indexes of activity (SLEDAI) and damage accrual (SLICC). The fact that the differences in SLICC are only observed in those patients treated with corticosteroids suggests that, maybe, only the accumulated damage related to taking corticosteroids could be mediated by AGEs.

References

[1]Medzhitov R. Origin and physiological roles of inflammation. Nature 2008;454:428–435.

[2]Vytášek R, Šedová L, Vilím V. Increased concentration of two different advanced glycation end-products detected by enzyme immunoassays with new monoclonal antibodies in sera of patients with rheumatoid arthritis. BMC Musculoskelet Disord 2010;11:83.

[3]leeuw K de, Graaff R, Vries R de, Dullaart RP, Smit AJ, Kallenberg CG, Bijl M. Accumulation of advanced glycation endproducts in patients with systemic lupus erythematosus. Rheumatology 2007;46:1551–1556.

[4]Meerwaldt R, Links T, Graaff R, Thorpe SR, Baynes JW, Hartog J, Gans R, Smit A. Simple noninvasive measurement of skin autofluorescence. Ann N Y Acad Sci 2005;1043:290-298.

Disclosure of Interests

None declared

AB1460 ACCUMULATED ADVANCED GLYCATION ENDPRODUCTS ARE SIGNIFICANTLY HIGHER IN PATIENTS WITH IMMUNE-MEDIATED INFLAMMATORY DISEASES THAN IN HEALTHY POPULATION

Background

Advanced glycation endproducts (AGEs) are the result of non-enzymatic glycation of proteins, lipids or nucleic acids. In circumstances characterized by increased oxidative and carbonyl stress, such as chronic inflammation, AGEs can be formed more rapidly1, generating reactive oxygen species and activating inflammatory signaling cascades through their chief signaling receptor (commonly abbreviated as RAGE)2. This positive feedback of inflammation can play a role in the etiology of immune-mediated inflammatory diseases, more specifically in rheumatoid arthritis (RA), ankylosing spondylitis (AS) and systemic lupus erythematosus (SLE).

Objectives

To investigate whether the accumulated concentrations of AGEs in patients with SLE, RA or AS are significantly higher than in healthy patients.

Methods

One hundred thirteen consecutive patients fulfilling ACR/EULAR criteria for RA, 60 patients fulfilling ASAS/OMERACT MRI criteria for AS, 97 patients fulfilling ACR/SLICC criteria for SLE and 527 sex-matched healthy controls were recruited.in cross-sectional study. Exclusion criteria were pregnancy, diabetes mellitus, corticosteroid treatment ≥ 20mg/day and malignant neoplasm. Accumulated AGEs were non-invasively measured by skin autofluorescence (Age Reader Mu Connect, Diagnostics Technologies B.V) and demographic and clinical data were collected. AGEs comparisons between patients and controls were performed by multiple linear regression analysis adjusted by confunders, previously described in literature (age, smoking habit and cardiovascular risk-factors). Age was centered at 55 years.

Results

Table 1 shows some descriptive characteristics of our cohorts. AGEs adjusted mean was significantly increased in SLE patients compared with matched controls (95% CI [2.27, 2.76] vs [1.66, 1.89], p<0.0001), RA patients and controls (95% CI [2.41, 2.61] vs [1.68, 1.88], p<0.0001) and AS patients and controls (95% CI [2.03, 2.6] vs [1.66, 1.93], p<0.0001). In all 3 models, AGEs were also significantly positive correlated with smoking habit measured by packs per year (p<0.001) and age (p<0.0001).

Table 1.

Descriptive characteristics of the cohorts

SLERAASPatientsControlsPatientsControlsPatientsControlsN=96N=189N=113N=240N=60N=99AGEs2.57 (0.65)1.98 (0.45)2.59 (0.58)2.00 (0.42)2.26 (0.46)1.90 (0.46)Age51.0 [43.0;61.0]56.0 [52.0;62.0]58.0 [54.0;65.0]61.0 [56.0;66.0]47.5 [41.0;55.0]53.0 [49.0;57.0]SmokerNo76 (79.2%)133 (70.4%)86 (76.1%)196 (81.7%)42 (70.0%)58 (58.6%)Yes20 (20.8%)56 (29.6%)27 (23.9%)44 (18.3%)18 (30.0%)41 (41.4%)Packs/year0.00 [0.00;10.8]2.50 [0.00;18.8]2.50 [0.00;18.0]0.00 [0.00;12.6]0.00 [0.00;7.88]14.9 [2.00;30.6]HypertensionNo74 (77.1%)116 (61.4%)77 (68.1%)146 (60.8%)53 (88.3%)75 (75.8%)Yes22 (22.9%)73 (38.6%)36 (31.9%)94 (39.2%)7 (11.7%)24 (24.2%)ObesityNo80 (83.3%)128 (67.7%)86 (76.1%)163 (67.9%)51 (85.0%)81 (81.8%)Yes16 (16.7%)61 (32.3%)27 (23.9%)77 (32.1%)9 (15.0%)18 (18.2%)DyslipidemiaNo85 (88.5%)104 (55.0%)79 (69.9%)108 (45.0%)51 (85.0%)55 (55.6%)Yes11 (11.5%)85 (45.0%)34 (30.1%)132 (55.0%)9 (15.0%)44 (44.4%)

Continuous normal: mean (SD); Continuous non-normal: median [IQR]; Categorical: absolute (relative frequency)

Conclusion

Accumulated AGEs in all 3 pathologies are significantly higher than in the healthy controls. The different means of AGEs in each of the diseases, being higher in SLE and lower in AS, may suggest a different participation of AGEs in the immune-mediated mechanisms of each pathology.

References

[1]K. de Leeuw, R. Graaff et al., Accumulation of advanced glycation endproducts in patients with systemic lupus erythematosus, Rheumatology, Volume 46, Issue 10, October 2007, Pg 1551–1556.

[2]Yan S., Ramasamy R. & Schmidt A. Mechanisms of Disease: advanced glycation end-products and their receptor in inflammation and diabetes complications. Nat Rev Endocrinol4, 285–293 (2008).

Disclosure of Interests

None declared

AB0047 CARTILAGE DEGRADATION STATUS OF KNEE OSTEOARTHIRTIC PATIENTS CAN BE PREDICTED BY CHONDROCYTE GENE EXPRESSION ANALYSIS

Background

Osteoarthritis (OA) is the most common degenerative joint disease, but its pathogenesis is still poorly understood. OA is characterized by articular cartilage loss due to an imbalance in anabolic and catabolic gene expression of the chondrocyte, together with aberrant expression of transcription factors and inflammatory mediators.

Objectives

We aim to evaluate de genes implicated in the chondrocyte failure regarding the four issues assessed to evaluate cartilage integrity using Mankin score (MkS): surface integrity, cellularity, cell cloning and staining.

Methods

Knee OA (KOA) patients aged 60-75 undergoing a total knee replacement, were recruited. At surgery, tibial plateau and femur condyles were deposited in DMEM medium and sent to the laboratory within 4 hours of the extraction. Punches from areas located at low, medium and high load (1) were excised from each sample (approximately 11 areas per patient). For RNA analysis, punches were kept in RNAlater at -20ºC until analyzed. RNA extraction, cDNA synthesis and cDNA amplification of the selected genes were performed previous to gene expression quantifycation by OpenArray Assay with custom plates. ΔCt was analyzed by ExpressionSuite V1.3 using 6 housekeeping genes. For histology study, punchs were fixated in formalin and embedded in parafin. Sections of 4 µm were stained with hematoxilin eosin and Safranin O-Fast Green. Slices were scored using the modified MkS (2) by 3 independent observers. R (v3.3.2) analysis was used to explored the results with principal components analysis (PCA) and linear regression (LR).

Results

Surgical samples were obtained from a total of 27 patients and 219 different areas were analyzed. ΔCt of the 51 genes analyzed by PCA showed that 9 components were enough to represent >80% of variance of the model. The genes associated with each component are summarized in Table 1. LR shows that second and first component were significantly associated to all or most of the fields included in the MkS, respectively. In contrast, component 4, 5 and 9 were not associated with any field. Lower expression of genes represented in component 1 (mainly related with extracellular matrix content) are associated with higher MkS values. On the other hand, component 2 summarizes data of genes mainly related with factors regulating cell metabolism. In this case, higher expression of TNFαIP6, NGF, IGFBP1, CRLF1, TNFα, and lower expression of ACAN, COL11A2, COL2A1, COL10A1, SOX9 and TGFβ1, among others, are associated with increased MkS values.

Table 1.

Genes that most contribute (by order) to component 1 & 2 (due to space limitation). Data of LR analysis for each component and MkS item. Significant association marked in bold.

ComponentGenesMankin score item (β coefficient; p-value)Surface integrityCellularityCell cloningStaining1SERPINE2, COL8A2, OGN, COL5A, TIMP3, BMP6, CRLF1, TIMP2, WISP1, ST3GAL1, SERPINE1, TNFSF10, ASPN, NGF, CD44, TNFRSF11B, TGFA, ADAMTS5, COL15A1, LUM, TNFAIP6, PTGS2, BMP2-0.092; 0.006-0.025; 0.047-0.028; 0.078-0.043; 0.0152ACAN, GPC5, CFH, FGFR3, COL11A2, TGFB1, GREM1, TNFAIP6, NGF, SOX9, IGFBP1, MMP3, FGF2, CRLF1, TNFa, COL2A1, COL10A10.261; 2.54 10-70.050; 0.0100.066; 0.0050.072; 0.0073-0.174; 0.003-0.029; 0.191-0.076; 0.0060.004; 0.89840.068; 0.410-0.019; 0.543-0.055; 0.161-0.021; 0.6275-0.082; 0.3640.051; 0.1460.020; 0.644-0.052; 0.28360.050; 0.6050.023; 0.5480.111; 0.0170.062; 0.2287-0.120; 0.266-0.090; 0.0320.010; 0.839-0.113; 0.0528-0.134; 0.2740.006; 0.892-0.198; 0.001-0.131; 0.0479-0.220; 0.096-0.041; 0.425-0.101; 0.1100.020; 0.780

Conclusion

There is a correlation between the expression level of the studied genes and the MkS values, although the role played by each gene might be different according to the MkS issue evaluated. These results could be useful to describe biomarkers that identify burden of disease in KOA.

References

[1]Adouni M, Shirazi-Adl A. J Orthop Res. 2014 Jan;32(1):69-78.

[2]Moody HR, Heard BJ, et al. J Anat. 2012 Jul;221(1):47-54.

Acknowledgements

We acknowledge Berend Bremmen for his help in Mankin Score bibliography revision and image scoring.

Disclosure of Interests

None declared

POS0179 IMPLICATIONS OF BRAIN ACTIVITY IN THE TREATMENT DECISION OF KNEE OSTEOARTHRITIS

Background

Chronic pain related to knee osteoarthritis (KOA) is a common health problem and functional magnetic resonance imaging (fMRI) is a useful technique which can determine different brain activation (1).

Objectives

The main purpose of our study was to observe whether there is different risk to central sensitization and different brain activation in patients with KOA according to the treatment followed (conservative (CNV) Vs. total knee replacement (TKR))

Methods

Patients diagnosed of primary KOA following a CNV treatment or undergoing TKR were recruited. The two groups were matched by age, sex and BMI. Clinical central sensitization was considered if patients presented spread tenderness, evaluated with an algometer, in more than 1 site of the extended peripatellar map (2) (notice that pain at points 3, 7 and 8 were not counted) fMRI testing involved pressure painful stimulation to the articular interline and to a commonly sensitized site (tibial surface, point 10).To evaluate the associations between central sensitization and the risk to undergo a TKR; logistic regression was performed to estimate OR and 95% confidence intervals (95%CI). Models were adjusted by sex, age and BMI (R (R v.3.5.2).Whole-brain activation maps were compared between groups using Statistical Parametric Mapping software (SPM12 http://www.fil.ion.ucl.ac.uk/spm).

Results

Women have a significant higher risk to present central sensitization than men (OD 12,11 (95% CI 4,32-33,95) p-value:2,09*106), but no differences were observed between CNV and TKR group (OR TKR 0,69 (95% CI 0,24-1,98)) (Table 1). The differences observed in brain activation between the treatment groups in the interline fMRI test (point 7) did not correspond to any specific brain area. However, TKR group showed a higher activation that implicated the region of the amygdala and anterior hippocampus during the tibial fMRI test (point 10).

Table 1.

Central sensitization Odds Ratio (OR) with 95% Confidence Interval (95%CI)

O.R. (95% CI)p-valueTreatment0.69 (0.24- 1.98)0,494Sex12.11 (4.32- 33.95)2,09*10-6Age0.72 (0.26- 1.97)0,525BMI1.88 (0.69- 5.17)0,219

Conclusion

Presenting central sensitization is not a risk for KOA patients to undergo a TKR, but the mechanism underlaying sensitization in both treatment groups might be different, with amygdala playing an important role in TKR patients. The amygdala is an important element of the brain systems that both express emotions and modulate pain. The activation of the amygdala in response to pressure stimulation on a sensitized knee site is interpreted as a failure of the descending pain inhibitory systems, and the occurrence of a major emotional response during the painful experience in patients that ultimately received TKR.

References

[1]Pujol, J. et al., 2017. Brain imaging of pain sensitization in patients with knee osteoarthritis. Pain, 158(9), pp.1831–1838.

[2]Arendt-Nielsen L, Nie H, Laursen MB, Laursen BS, Madeleine P, Simonsen OH, Graven-Nielsen T. Sensitization in patients with painful knee osteoarthritis. Pain 2010;149:573-8

Extended peripatellar map including the points tested for tenderness, and brain areas differently activated between both treatments groups during painful stimulation to point 7 (interline) and point 10 (tibial surface, a commonly sensitized site).

Disclosure of Interests

None declared

Evaluation of a single-shot of a high-density viscoelastic solution of hyaluronic acid in patients with symptomatic primary knee osteoarthritis: the no-dolor study

BACKGROUND

Pronolis®HD mono 2.5% is a novel, one-shot, high-density sterile viscoelastic solution, recently available in Spain, which contains a high amount of intermediate molecular weight hyaluronic acid (HA), highly concentrated (120 mg in 4.8 mL solution: 2.5%). The objective of the study was to analyze the efficacy and safety of this treatment in symptomatic primary knee osteoarthritis (OA).

METHODS

This observational, prospective, multicenter, single-cohort study involved 166 patients with knee OA treated with a single-shot of Pronolis®HD mono 2.5% and followed up as many as 24 weeks.

RESULTS

Compared with baseline, the score of the Western Ontario and McMaster Universities Arthritis Osteoarthritis Index (WOMAC) pain subscale reduced at the 12-week visit (primary endpoint, median: 9 interquartile range [IQR]: 7-11 versus median: 4; IQR: 2-6; p < 0.001). The percentage of patients achieving > 50% improvement in the pain subscale increased progressively from 37.9% (at 2 weeks) to 66.0% (at 24 weeks). Similarly, WOMAC scores for pain on walking, stiffness subscale, and functional capacity subscale showed significant reductions at the 12-week visit which were maintained up to the 24-week visit. The EuroQol visual analog scale score increased after 12 weeks (median: 60 versus 70). The need for rescue medication (analgesics/nonsteroidal anti-inflammatory drugs) also decreased in all post-injection visits. Three patients (1.6%) reported local adverse events (joint swelling) of mild intensity.

CONCLUSIONS

In conclusion, a single intra-articular injection of the high-density viscoelastic gel of HA was associated with pain reduction and relief of other symptoms in patients with knee OA.

TRIAL REGISTRATION

ClinicalTrial# NCT04196764.

Fibronectin-coating enhances attachment and proliferation of mesenchymal stem cells on a polyurethane meniscal scaffold

Introduction

Partial meniscectomy is one of the most common surgical strategy for a meniscal injury, but sometimes, patients complain of knee pain due to an overload in the ablated compartment. In these cases, implantation of tissue engineering scaffold could be indicated. Currently, two commercial scaffolds, based on collagen or polycaprolactone-polyurethane (PCL-PU), are available for meniscus scaffolding. In short term follow-up assessments, both showed clinical improvement and tissue formation. However, long-term studies carried out in PCL-PU showed that the new tissue decreased in volume and assumed an irregular shape. Moreover, in some cases, the scaffold was totally reabsorbed, without new tissue formation.

Mesenchymal stem cells (MSCs) combined with scaffolds could represents a promising approach for treating meniscal defects because of their multipotency and self-renewal. In this work, we aimed to compare the behaviour of MSCs and chondrocytes on a PCL-PU scaffold in vitro. MSCs express integrins that binds to fibronectin (FN), so we also investigate the effect of a FN coating on the bioactivity of the scaffold.

Methods

We isolated rabbit bone marrow MSCs (rBM-MSCs) from two skeletally mature New Zealand white rabbits and stablished the optimum culture condition to expand them. Then, they were seeded over non-coated and FN-coated scaffolds and cultured in chondrogenic conditions. To evaluate cell functionality, we performed an MTS assay to compare cell proliferation between both conditions. Finally, a histologic study was performed to assess extracellular matrix (ECM) production in both samples, and to compare them with the ones obtained with rabbit chondrocytes (rCHs) seeded in a non-coated scaffold.

Results

A culture protocol based on low FBS concentration was set as the best for rBM-MSCs expansion. The MTS assay revealed that rBM-MSCs seeded on FN-coated scaffolds have more cells on proliferation (145%; 95% CI: 107%–182%) compared with rBM-MSCs seeded on non-coated scaffolds. Finally, the histologic study demonstrated that rCHs seeded on non-coated scaffolds displayed the highest production of ECM, followed by rBM-MSCs seeded on FN-coated scaffolds. Furthermore, both cell types produced a comparable ECM pattern.

Conclusion

These results suggest that MSCs have low capacity attachment to PCL-PU scaffolds, but the presence of integrin alpha5beta1 (FN-receptor) in MSCs allows them to interact with the FN-coated scaffolds. These results could be applied in the design of scaffolds, and might have important clinical implications in orthopaedic surgery of meniscal injuries.

•

Cultures with low FBS are more suitable to isolation and expansion of rBM-MSC.

•

PCL-PU scaffolds coated with FN show improve adhesion properties for rBM-MSCs.

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rBM-MSCs seeded in PCL-PU + FN produce ECM similar to the one produced by chondrocytes.

Evidence-Based Network Modelling to Simulate Nucleus Pulposus Multicellular Activity in Different Nutritional and Pro-Inflammatory Environments

Initiation of intervertebral disc degeneration is thought to be biologically driven. This reflects a process, where biochemical and mechanical stimuli affect cell activity (CA) that compromise the tissue strength over time. Experimental research enhanced our understanding about the effect of such stimuli on different CA, such as protein synthesis or mRNA expression. However, it is still unclear how cells respond to their native environment that consists of a “cocktail” of different stimuli that might locally vary. This work presents an interdisciplinary approach of experimental and in silico research to approximate Nucleus Pulposus CA within multifactorial biochemical environments. Thereby, the biochemical key stimuli glucose, pH, and the proinflammatory cytokines TNF-α and IL1β were considered that were experimentally shown to critically affect CA. To this end, a Nucleus Pulposus multicellular system was modelled. It integrated experimental findings from in vitro studies of human or bovine Nucleus Pulposus cells, to relate the individual effects of targeted stimuli to alterations in CA. Unknown stimulus-CA relationships were obtained through own experimental 3D cultures of bovine Nucleus Pulposus cells in alginate beads. Translation of experimental findings into suitable parameters for network modelling approaches was achieved thanks to a new numerical approach to estimate the individual sensitivity of a CA to each stimulus type. Hence, the effect of each stimulus type on a specific CA was assessed and integrated to approximate a multifactorial stimulus environment. Tackled CA were the mRNA expressions of Aggrecan, Collagen types I & II, MMP3, and ADAMTS4. CA was assessed for four different proinflammatory cell states; non-inflamed and inflamed for IL1β, TNF-α or both IL1β&TNF-α. Inflamed cell clusters were eventually predicted in a multicellular 3D agent-based model. Experimental results showed that glucose had no significant impact on proinflammatory cytokine or ADAMTS4 mRNA expression, whereas TNF-α caused a significant catabolic shift in most explored CA. In silico results showed that the presented methodology to estimate the sensitivity of a CA to a stimulus type importantly improved qualitative model predictions. However, more stimuli and/or further experimental knowledge need to be integrated, especially regarding predictions about the possible progression of inflammatory environments under adverse nutritional conditions. Tackling the multicellular level is a new and promising approach to estimate manifold responses of intervertebral disc cells. Such a top-down high-level network modelling approach allows to obtain information about relevant stimulus environments for a specific CA and could be shown to be suitable to tackle complex biological systems, including different proinflammatory cell states. The development of this methodology required a close interaction with experimental research. Thereby, specific experimental needs were derived from systematic in silico approaches and obtained results were directly used to enhance model predictions, which reflects a novelty in this research field. Eventually, the presented methodology provides modelling solutions suitable for multiscale approaches to contribute to a better understanding about dynamics over multiple spatial scales. Future work should focus on an amplification of the stimulus environment by integrating more key relevant stimuli, such as mechanical loading parameters, in order to better approximate native physiological environments.

COVID-19 Incidence in Patients With Immunomediated Inflammatory Diseases: Influence of Immunosuppressant Treatments

The effect of immunosuppressant treatments on the incidence of coronavirus disease (COVID-19) remains largely unknown. We studied the association between the pre-exposure to disease-modifying antirheumatic drugs (DMARDs) that decrease immunological responses and the incidence of COVID-19 to explore the possible effects of these treatments in early manifestations of the disease. For this purpose, we performed a cross-sectional study including 2,494 patients with immunomediated inflammatory diseases (IMIDs) recruited at the outpatient Rheumatology, Dermatology and Gastroenterology services of Hospital del Mar. The primary outcome was the clinical diagnosis of COVID-19 performed by a physician at the hospital or at the primary care center, from the March 1-29, 2020. Multivariable Poisson regression models were fitted to estimate COVID-19 relative risk (RR) adjusted by comorbidities. We revealed that biological (RR = 0.46, CI 95% = 0.31-0.67) and synthetic (RR = 0.62, CI 95% = 0.43-0.91) DMARDs used in IMIDs diminished the incidence of COVID-19. Striking sex differences were revealed with anti-TNFα compounds (RR = 0.50, CI 95% = 0.33-0.75) with higher effects in women (RR = 0.33, CI 95% = 0.17-0.647). Treatment with low glucocorticoid doses also revealed sex differences decreasing the incidence of COVID-19 predominantly in women (RR = 0.72, CI 95% = 0.42-1.22). Our results report a decreased incidence of COVID-19 in patients receiving specific DMARDs with different immunodepressor mechanisms with striking sex differences. These results underline the interest of repurposing specific DMARDs for the possibility of minimizing the severity of disease progression in the early stages of COVID-19.

FRI0426 EMOTIONAL COMPONENTS AND INFLAMMATION ARE HIGHLY RELEVANT IN PAIN REPORTED BY KNEE OSTEOARTHRITIC PATIENTS

Background:

Osteoarthritis (OA) is a leading cause of disability in elderly and the most frequent form is knee OA (KOA) (1). Pain is the principal symptom that leads patients to visit clinicians, and it is the main reason, together with functionality, for patients to undergo a total knee replacement (TKR) after apparently unsuccessful conservative (CNV) treatments (2). It is well-known that there is a poor correlation between the radiographic severity (based on Kellgren & Lawrence (KL) score) and the reported pain (3), so other variables may be responsible for the intensity of pain.

Objectives:

Identifying the leading causes of pain in each patient would improve the management of the disease. In this study we aim to investigate the role of emotional components, nociception process and inflammation in treatment decision, as a global measure of pain suffered by KOA patients, taking into account sex, age and BMI.

Methods:

KOA patients, carefully selected to be idiopathic, graded 2-3 in KL, were recruited at Hospital del Mar. The following variables were recorded: WOMAC, Hospital Anxiety and Depression Scale (HAD), Pain Catastrophizing Scale (PCS), tender points (TP) (measure with a pressure algometer at points defined in the Arendt-Nielsen extended peripatellar map), synovial hypertrophy (SH) and effusion (SE) (measure by ultrasounds), and PCR and ESR serum levels. Patients were classified according to 4 factors: treatment (CNV/TKR), sex, age (60-67/68-75) and BMI (<30/>30). All groups were balanced. Multivariate and correlations analysis were performed.

Results:

Eighty-seven patients have been recruited. Patients from the TKR group present significant higher WOMAC (p=0.000), PCS (p=0.002) and SE (p= 0.038) values than CNV ones, without interaction with the other factors, except for SE, that presents interaction with BMI (Fig. 1). Women reported significant upper WOMAC (p=0.001) and HAD rates (p=0.020), but also higher number of TP and ESR levels (p= 0.000 and 0.002, respectively). The level of sensitization was significantly higher in women than in men (p=0.000). Several significant correlations were found, mainly between WOMAC and emotional components, as well as between TP and WOMAC, PCS, and inflammation markers (Table 1).

Conclusion:

PCS is an emotional component that could explain in part the lack of correlation between joint status and patient’s symptomatology. Working out strategies for pain management could improve this PCS values and therefore reduce the need for TKR. Furthermore, this study also highlights the two mainly types of OA etiology: mechanical and inflammatory. It suggests that inflammation is mostly responsible for OA progression in patients with low BMI, and plays a strong role in women pathology. Finally, specific treatments targeting central pain sensitization could also improve the management of the pathology in women.

References:

[1]Guccione AA, Felson DT, Anderson JJ, Anthony JM, Zhang Y, Wilson PW, et al. The effects of specific medical conditions on the functional limitations of elders in the Framingham Study. Am J Public Health. 1994 Mar;84(3):351-8.

[2]O’Neill TW, Felson DT. Mechanisms of Osteoarthritis (OA) Pain. Curr Osteoporos Rep. 2018 Oct;16(5):611-6.

[3]Dieppe PA. Relationship between symptoms and structural change in osteoarthritis. what are the important targets for osteoarthritis therapy? J Rheumatol Suppl. 2004 Apr;70:50-3.

Acknowledgments:

MICINN Funds are acknowledged (HOLOA-DPI2016-80283-C2-1/2-R)

Disclosure of Interests:

None declared

AB0874 FUNCTIONALITY IN OSTEOARTHRITIC GAIT IS RELATED TO TREATMENT DECISION. A MULTIFACTORIAL ANALYSIS

Background:

Osteoarthritis (OA) is a degenerative disease with complex underling mechanisms1–3. The interactions among several factors make the study of the disease very complex and often lead to different treatment, i.e. surgical or conservative, decisions for subjects clinically and radiographically similar. Recent explorations performed at the body level pointed out that macro-factors, like overweight or gait, can influence the development of the disease4. The number of related factors is high, and they are very likely to interact with each other. However, the literature lacks randomized and balanced studies to verify such effects of multiple factors5.

Objectives:

The aim of this work was to develop a multifactorial analysis to explore whether and how gait functionality and dynamics can be related to treatment decision.

Methods:

A multifactorial analysis of gait dynamics in OA subjects was developed. 81 OA subjects, graded 2-3 in KL, were selected based on 4 clinical factors: Gender (male – female), Age (60-67 – 68-75), BMI (25–29.9 – 30+) and Treatment (total knee replacement (TKR) – conservative treatment). Gait analysis was performed using 8 cameras BTS Smart-DX 700, 1.5 Mpixels 250 fps and 2 force plates BTS P-6000 500 Hz sampling (BTS S.p.A., Milan, Italy). Helen Hayes marker protocol with medial markers was used for the study. Each volunteer was asked to perform a minimum of 5 valid gait sequences. Functionality and dynamics parameters were measured.

Functionality: Velocity of gait and the time needed to perform a gait cycle were computed.

Dynamics:The reaction forces and torques at the ankles, knees and hips were computed through inverse dynamic analyses.

Analysis of variance was performed for the four factors described among the functionality and dynamics parameters.

Results:

The multifactorial analysis showed that functionality values are more subjective to the studied factors than the dynamics ones.

Functionalityseems to be directly related to the clinical treatment. Patients who selected TKR needed more time to make a step, spent more time in double stand position and walked slower (p<0.002). Older subject also walked slower but this dependency seemed to variate with age (interaction between clinical treatment and age – p<0.02 – Figure 1).

Figure 1

Interaction between Clinical treatment and age.

Dynamics: Forces at the joints seemed to be affected by the gender and an interaction between age and BMI (p< p<0.005, p<0.02) but not by the kind of therapy. Differently, torques were statistically related to the clinical treatment (p<0.007). Age was also significant as was the interaction between age and BMI (both p<0.007).

Conclusion:

Reduced functionality seems to be related to the selection of therapy. In contrast to current paradigm, forces at the joints may have no role in the definition of the best therapy for OA subjects. Subjects requiring TKR do not present higher loads at the joints. However, torques seems to be related to the therapy selected. Instead of forces, kinematics and posture assessments might support rational definitions of the therapy and future multifactorial analysis should take them into consideration.

References:

[1]Ding M. et al.J Bone Joint Surg Br. 2003;85(6):906-912.

[2]Kamibayashi L. et al.Calcif Tissue Int. 1995;57:69-73.

[3]Li B, Aspden RM.J Bone Miner Res. 1997;12(4):641-651.

[4]Berenbaum F et al.Curr Opin Rheumatol. 2013;25(1):114-118.

[5]Ioannidis JPA.Soc Sci Med. 2018;210(April):53-56.

Acknowledgments:

MICINN Funds are acknowledged (HOLOA-DPI2016-80283-C2-1/2-R, RYC-2015-18888)

Disclosure of Interests:

None declared

In vivo effect of opticin deficiency in cartilage in a surgically induced mouse model of osteoarthritis

The SLRP opticin (OPTC) has been demonstrated to be produced and degraded in osteoarthritic (OA) human cartilage. Here, we investigated the in vivo effect of OPTC deficiency in OA cartilage. OA was induced in 10-week-old Optc^−/− and Optc^+/+ mice. Ten weeks post-surgery, cartilage was processed for histology and immunohistochemistry. SLRP expression was determined in non-operated mouse cartilage. OA Optc^−/− demonstrated significant protection against cartilage degradation. Data revealed that in non-operated Optc^−/− cartilage, expression of SLRPs lumican and epiphycan was up-regulated at day 3 and in 10-week-olds (p ≤ 0.039), and fibromodulin down-regulated in 10-week-olds (p = 0.001). Immunohistochemistry of OA mice showed a similar pattern. In OA Optc^−/− cartilage, markers of degradation and complement factors were all down-regulated (p ≤ 0.038). In OA Optc^−/− cartilage, collagen fibers were thinner and better organized (p = 0.038) than in OA Optc^+/+ cartilage. The protective effect of OPTC deficiency during OA results from an overexpression of lumican and epiphycan, known to bind and protect collagen fibers, and a decrease in fibromodulin, contributing to a reduction in the complement activation/inflammatory process. This work suggests that the evaluation of the composition of the different SLRPs in OA cartilage could be applied as a new tool for OA prognosis classification.

A Genome-wide Association Study Identifies Risk Alleles in Plasminogen and P4HA2 Associated with Giant Cell Arteritis

Giant cell arteritis (GCA) is the most common form of vasculitis in individuals older than 50 years in Western countries. To shed light onto the genetic background influencing susceptibility for GCA, we performed a genome-wide association screening in a well-powered study cohort. After imputation, 1,844,133 genetic variants were analyzed in 2,134 case subjects and 9,125 unaffected individuals from ten independent populations of European ancestry. Our data confirmed HLA class II as the strongest associated region (independent signals: rs9268905, p = 1.94 × 10^-54, per-allele OR = 1.79; and rs9275592, p = 1.14 × 10^-40, OR = 2.08). Additionally, PLG and P4HA2 were identified as GCA risk genes at the genome-wide level of significance (rs4252134, p = 1.23 × 10^-10, OR = 1.28; and rs128738, p = 4.60 × 10^-9, OR = 1.32, respectively). Interestingly, we observed that the association peaks overlapped with different regulatory elements related to cell types and tissues involved in the pathophysiology of GCA. PLG and P4HA2 are involved in vascular remodelling and angiogenesis, suggesting a high relevance of these processes for the pathogenic mechanisms underlying this type of vasculitis.

Healthy and Osteoarthritic Synovial Fibroblasts Produce a Disintegrin and Metalloproteinase with Thrombospondin Motifs 4, 5, 7, and 12: Induction by IL-1β and Fibronectin and Contribution to Cartilage Damage

Current description of osteoarthritis includes the involvement of synovial inflammation. Studies contributing to understanding the mechanisms of cross-talk and feedback among the joint tissues could be relevant to the development of therapies that block disease progression. During osteoarthritis, synovial fibroblasts exposed to anomalous mechanical forces and an inflammatory microenvironment release factors such as a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS) metalloproteinases that mediate tissue damage and perpetuate inflammation. We therefore studied the production of ADAMTS by synovial fibroblasts and their contribution to cartilage degradation. Moreover, we analyzed the implication of two mediators present in the osteoarthritis joint, IL-1β as proinflammatory cytokine, and 45-kDa fibronectin fragments as products of matrix degradation. We reported that synovial fibroblasts constitutively express and release ADAMTS 4, 5, 7, and 12. Despite the contribution of both mediators to the stimulation of Runx2 and Wnt/β-catenin signaling pathways, as well as to ADAMTS expression, promoting the degradation of aggrecan and cartilage oligomeric matrix protein from cartilage, fibronectin fragments rather than IL-1β played the major pathological role in osteoarthritis, contributing to the maintenance of the disease. Moreover, higher levels of ADAMTS 4 and 7 and a specific regulation of ADAMTS-12 were observed in osteoarthritis, suggesting them as new potential therapeutic targets. Therefore, synovial fibroblasts provide the biochemical tools to the chronicity and destruction of the osteoarthritic joints.

A large-scale genetic analysis reveals a strong contribution of the HLA class II region to giant cell arteritis susceptibility

We conducted a large-scale genetic analysis on giant cell arteritis (GCA), a polygenic immune-mediated vasculitis. A case-control cohort, comprising 1,651 case subjects with GCA and 15,306 unrelated control subjects from six different countries of European ancestry, was genotyped by the Immunochip array. We also imputed HLA data with a previously validated imputation method to perform a more comprehensive analysis of this genomic region. The strongest association signals were observed in the HLA region, with rs477515 representing the highest peak (p = 4.05 × 10(-40), OR = 1.73). A multivariate model including class II amino acids of HLA-DRβ1 and HLA-DQα1 and one class I amino acid of HLA-B explained most of the HLA association with GCA, consistent with previously reported associations of classical HLA alleles like HLA-DRB1(∗)04. An omnibus test on polymorphic amino acid positions highlighted DRβ1 13 (p = 4.08 × 10(-43)) and HLA-DQα1 47 (p = 4.02 × 10(-46)), 56, and 76 (both p = 1.84 × 10(-45)) as relevant positions for disease susceptibility. Outside the HLA region, the most significant loci included PTPN22 (rs2476601, p = 1.73 × 10(-6), OR = 1.38), LRRC32 (rs10160518, p = 4.39 × 10(-6), OR = 1.20), and REL (rs115674477, p = 1.10 × 10(-5), OR = 1.63). Our study provides evidence of a strong contribution of HLA class I and II molecules to susceptibility to GCA. In the non-HLA region, we confirmed a key role for the functional PTPN22 rs2476601 variant and proposed other putative risk loci for GCA involved in Th1, Th17, and Treg cell function.

Reduced proliferation and osteocalcin expression in osteoblasts of male idiopathic osteoporosis

Osteoporosis is characterized by low bone mineral density (BMD), resulting in increasing susceptibility to bone fractures. In men, it has been related to some diseases and toxic habits, but in some instances the cause of the primary--or idiopathic--osteoporosis is not apparent. In a previous study, our group compared histomorphometric measurements in cortical and cancellous bones from male idiopathic osteoporosis (MIO) patients to those of control subjects and found reduced bone formation without major differences in bone resorption. To confirm these results, this study analyzed the etiology of this pathology, examining the osteoblast behavior in vitro. We compared two parameters of osteoblast activity in MIO patients and controls: osteoblastic proliferation and gene expression of COL1A1 and osteocalcin, in basal conditions and with vitamin D(3) added. All these experiments were performed from a first-passage osteoblastic culture, obtained from osteoblasts that had migrated from the transiliac explants to the plate. The results suggested that the MIO osteoblast has a slower proliferation rate and decreased expression of genes related to matrix formation, probably due to a lesser or slower response to some stimulus. We concluded that, contrary to female osteoporosis, in which loss of BMD is predominantly due to increased resorption, low BMD in MIO seems to be due to an osteoblastic defect.

The Zn- and Cd-clusters of recombinant mammalian MT1 and MT4 metallothionein domains include sulfide ligands

Recombinant (E. coli ) synthesis of mammalian MT1 and MT4 domains as separate peptides in Zn(II) and Cd(II) enriched growth media has rendered metal complexes containing sulfide anions as additional ligands. The Cd preparations show higher sulfide content than the Zn preparations. Also, the betaMT1 and betaMT4 fragments exhibit higher sulfide/peptide ratios than the respective alpha fragments. Titration of Zn3-betaMT1 with Cd(II) followed by addition of several sodium sulfide equivalents shows that the Cd(II)-betaMT1 species can incorporate sulfide ligands in vitro, with a concomitant evolution of their UV-vis and CD fingerprints to those characteristic of the Cd-S2- chromophores. Current results have also provided full understanding of previous data collected by this group in the characterization of the Cd-betaMT1 preparations obtained from large-scale fermentor synthesis by allowing identification of at least 2S2- ligands per Cd-betaMT1 species. Furthermore, the results here presented have revealed that synthesis of betaMT4 in Cd-supplemented cultures yielded Cd,S(2-)-containing clusters instead of the proposed heterometallic Zn,Cd-betaMT4 complexes. Finally, a global evaluation of our results suggests that the higher the Cu-thionein character of a MT peptide, the higher is its tendency to harbor nonproteic ligands (i.e., sulfide anions) when building divalent metal clusters, especially Cd-MT complexes.

Comparative metal binding and genomic analysis of the avian (chicken) and mammalian metallothionein

Chicken metallothionein (ckMT) is the paradigm for the study of metallothioneins (MTs) in the Aves class of vertebrates. Available literature data depict ckMT as a one-copy gene, encoding an MT protein highly similar to mammalian MT1. In contrast, the MT system in mammals consists of a four-member family exhibiting functional differentiation. This scenario prompted us to analyse the apparently distinct evolutionary patterns followed by MTs in birds and mammals, at both the functional and structural levels. Thus, in this work, the ckMT metal binding abilities towards Zn(II), Cd(II) and Cu(I) have been thoroughly revisited and then compared with those of the mammalian MT1 and MT4 isoforms, identified as zinc- and copper-thioneins, respectively. Interestingly, a new mechanism of MT dimerization is reported, on the basis of the coordinating capacity of the ckMT C-terminal histidine. Furthermore, an evolutionary study has been performed by means of in silico analyses of avian MT genes and proteins. The joint consideration of the functional and genomic data obtained questions the two features until now defining the avian MT system. Overall, in vivo and in vitro metal-binding results reveal that the Zn(II), Cd(II) and Cu(I) binding abilities of ckMT lay between those of mammalian MT1 and MT4, being closer to those of MT1 for the divalent metal ions but more similar to those of MT4 for Cu(I). This is consistent with a strong functional constraint operating on low-copy number genes that must cope with differentiating functional limitation. Finally, a second MT gene has been identified in silico in the chicken genome, ckMT2, exhibiting all the features to be considered an active coding region. The results presented here allow a new insight into the metal binding abilities of warm blooded vertebrate MTs and their evolutionary relationships.

Influence of chloride ligands on the structure of Zn- and Cd-metallothionein species

It is now commonly accepted that non-proteic ligands contribute to the structure and stability of metal-metallothionein (M-MT) species, although this contribution may differ substantially depending on the MT and the metal ions involved. Conversely, literature data are unconnected, lacking correlation studies between the contribution of inorganic ligands to the M-MT complexes and the corresponding CD and UV-vis fingerprints. To contribute towards filling this gap, we have analyzed the influence of chloride anions in the Zn- and Cd-MT complexes of mammalian MT1 and MT4 isoforms. Starting from the initial hypothesis that the shoulders appearing at 240nm in the UV-vis difference spectra during the Cd(II) titrations of Zn-MTs would be indicative of chloride participation in these metal-MT complexes, we can now propose that, while their absence definitely rules out these ligands being involved in metal coordination, their presence should not necessarily be attributed to the formation of metal-Cl bonds. Instead, we identified a global blue shift for the UV-vis difference spectral envelope as the most liable indication of chloride participation in the binding sites of the M-MT species. Following this criterion, we determined that chloride anions are bound to the Cd(7)-MT1 and Cd(4)-alphaMT1 complexes but not in the isostoichiometric Zn complexes, nor in the Zn- or Cd-complexes of the homologous MT4 peptides.

Functional differentiation in the mammalian metallothionein gene family: metal binding features of mouse MT4 and comparison with its paralog MT1

This paper reports on the characterization of the metal binding abilities of mammalian MT4 and their comparison with those of the well known MT1. Heterologous Escherichia coli expression in cultures supplemented with zinc, cadmium, or copper was achieved for MT4 and for its separate alphaMT4 and betaMT4 domains as well as for MT1 and its alphaMT1 domain in cadmium-enriched medium. The in vivo conformed metal complexes and the in vitro substituted zinc/cadmium and zinc/copper MT4 aggregates were characterized. Biosynthesis of MT4 and betaMT4 in Cd(II)-supplemented medium revealed that these peptides failed to form the same homometallic species as MT1, thus appearing less effective for cadmium coordination. Conversely, the entire MT4 and both of its domains showed better Cu(I) binding properties than MT1, affording Cu(10)-MT4, Cu(5)-alphaMT4 and Cu(7)-betaMT4, stoichiometries that make the domain dependence toward Cu(I) clear. Overall results allow consideration of MT4 as a novel copper-thionein, made up of two copper-thionein domains, the first of this class reported in mammals, and by extension in vertebrates. Furthermore, the in silico protein sequence analyses corroborated the copper-thionein nature of the MT4 peptides. As a consequence, there is the suggestion of a possible physiological role played by MT4 related with copper requirements in epithelial differentiating tissues, where MT4 is expressed.