Osteoarthritis (OA) pain implies an indication for joint replacement in patients with end-stage OA. However, chronic postoperative pain is observed in 10–40% of patients with OA. Here, we identified genes whose expression in the peripheral blood before surgery could denote the risk of postoperative pain development. We examined the peripheral blood of 26 healthy subjects and 50 patients with end-stage OA prior to joint replacement surgery. Pain was evaluated before surgery using the visual analog scale (VAS) index and neuropathic pain questionnaires, Douleur Neuropathique 4 Questions (DN4) and PainDETECT questionnaires. Functional activity was assessed using the Western Ontario and McMaster Universities osteoarthritis index (WOMAC). Three and six months after surgery, pain indices according to VAS of 30% and higher were considered. Metalloproteinase (MMP)-9 and tissue inhibitor of metalloproteinase (TIMP)1 protein levels were measured using ELISA in the peripheral blood mononuclear cells (PBMCs). Total RNA isolated from whole blood was analysed using quantitative real-time RT-PCR for caspase-3, MMP-9, TIMP1, cathepsins K and S, tumour necrosis factor (TNF)α, interleukin (IL)-1β, and cyclooxygenase (COX)-2 gene expression. Seventeen patients reported post-surgical pain. Expression of cathepsins K and S, caspase-3, TIMP1, IL-1β, and TNFα genes before surgery was significantly higher in these patients compared to pain-free patients with OA. Receiver-operating characteristic (ROC) curve analyses confirmed significant associations between these gene expressions and the likelihood of pain development after arthroplasty. High baseline expression of genes associated with extracellular matrix destruction (cathepsins S and K, TIMP1), inflammation (IL-1β, TNFα), and apoptosis (caspase-3) measured in the peripheral blood of patients with end-stage OA before knee arthroplasty might serve as an important biomarker of postoperative pain development.

Background:Osteoarthritis (OA) is a chronic rheumatic disease, which involves pain, limited inflammation and local destruction of the knee joint. OA pain is a major clinical symptom, which limits working capacity and denotes an important indication for joint replacement in the end-stage OA. In spite of significant number of positive outcomes, chronic postoperative pain represents a major adverse consequence of surgery, which is observed in 10-40% of OA patients. Therefore, identification of patients potentially capable of developing chronic postoperative pain prior to surgery could significantly improve therapy outcome. Central sensitization is in charge of pain symptoms in about 30% of end-stage OA patients. Several recently identified molecular markers such as cytokines, chemokines, calcium and glutamate transporters, caspases, and proteases has been shown to be responsible for central sensitization. Therefore, we hypothesized that genes related to pain sensitization whose expression is upregulated in about 30% of the examined end-stage OA patient cohort might be responsible for postoperative pain.Objectives:To outline an approach for search of biomarkers related to chronic postoperative pain development before joint replacement in the peripheral blood of end-stage OA patients.Methods:We examined peripheral blood of 26 healthy volunteers (average age 55±8.3 years old) and 53 end-stage OA patients (average age 56.5±8.9 years old) undergoing joint replacement surgery. MMP-9, TIMP1, TGFβ1, and caspase 3 protein levels were quantified by ELISA. Total RNA isolated from whole blood was used in expression studies for the genes related to central sensitization such as mechanistic target of rapamycin, mTOR; caspase 3; metalloproteinase (MMP)-9; tissue inhibitor of metalloproteinase TIMP1; cathepsins K and S; interleukin (IL)-1β; cyclooxygenase (COX)2; tumor necrosis factor (TNF)α, and transforming growth (TGF)β1. These were performed with quantitative real-time RT-PCR.Results:Retrospective analysis of gene expression in the peripheral blood of end-stage OA patients before joint replacement surgery revealed that gene expression data for TNFα, IL-1β, COX2, TGFβ1, and mTOR were not applicable as these gene expressions were significantly higher compared to healthy controls in all the examined OA patients. High expression of pain associated cathepsin S in 17% of the examined OA patients and cathepsin K, in 21% might indicate the possibility of postoperative pain development in these OA patients. In contrast, low expression of caspase 3 in 43% of the examined OA patients and MMP-9, in 23%, might point toward the absence of postoperative pain in these subjects.Conclusion:Gene expression analysis in the peripheral blood of the end-stage OA patients measured before joint replacement surgery might represent an approach for prediction of postoperative pain development. Disclosure of Interests: : None declared

Postoperative pain (POP) is a serious complication that reduces the result of total knee (TKA) or hip arthroplasty (THA) in patients with osteoarthritis (OA). The search for predictors of postoperative pain is an actual problem.The aim of the study – to assessing relationship the polymorphisms of the KCNS1, COMT and OPRM1 genes and the development of POP in OA patients who underwent TKA or THA.Material and methods. The study group consisted of 95 patients with OA knee or hip (64.6% of women, 65.4±9.0 years) who underwent TKA (47.8%) or THA (52.2%). The presence of POP was determined when pain in the area of surgical intervention ≥40 mm (100 mm visual analog scale, VAS) persisted or appeared 3 and 6 months after surgery. All patients underwent genotyping of polymorphisms of the genes KCNS1 (rs734784), COMT (rs6269, rs4633) and OPRM1 (rs1799971) by polymerase chain reaction in real time using original sequence-specific primers and samples labeled with various fluorescent labels. Registration and interpretation of the obtained results were carried out on the DT-96 amplifier (DNA-Technology LLC, Russia).Results. POP was observed in 32.6% of patients who underwent TKA or THA. The frequency of POP after TKA and THA was 30.2% and 34.0% (p=0.882). Statistical analysis revealed no differences in the frequencies of the genotypes of the studied genes (p>0,05). The presence of a homozygous genotype of the GG polymorphism of the KCNS1 gene (rs734784) was associated with the presence of POP in accordance with the recessive genetic model (GG vs AA+AG; odds ratio (OR) – 3.96 [95% confidence interval (CI): 1.51; 10.37]; p=0.005). The presence of the mutant allele T (TT+CT) in the genotype of the COMT polymorphism (rs4633) reduced the risk of POP compared to the carrier of the CC genotype (OR=0.32 [95% CI: 0.12; 0.83]; p=0.02) in accordance with the dominant genetic model. There was no significant correlation between the development of POP and the carrier of different genotypes and alleles of the COMT (rs6269) and OPRM1 (rs1799971) genes.Conclusions. There is a statistically significant association the polymorphism of the KCNS1 (rs734784) and COMT (rs4633) genes and the development of chronic POP in patients who underwent TKA or THA. Further studies of the genetic predisposition to POP are required on more clinical material.

Background:Osteoarthritis (OA) is a chronic rheumatic disease, which involves pain, limited inflammation, and local destruction of the knee joint. OA pain is a major clinical symptom, which limits working capacity and denotes an important indication for joint replacement in the end-stage OA. In spite of significant number of positive outcomes, chronic postoperative pain represents a major adverse consequence of surgery, which is observed in 10-40% of OA patients. Therefore, identification of patients potentially capable of developing chronic postoperative pain prior to surgery could significantly improve therapy outcome. Recently we hypothesized that genes related to pain sensitization whose expression is upregulated in about 10-40% of the examined end-stage OA patient cohort might be responsible for postoperative pain. Retrospective analysis of gene expression in the peripheral blood of end-stage OA patients before joint replacement surgery revealed that expression of cathepsins S and K, caspase 3, and MMP-9 genes might be associated with postoperative pain development [Ann Rheum Dis,78, suppl 2:A520].Objectives:To examine the validity of our hypothesis in the prospective study.Methods:We examined peripheral blood of 26 healthy volunteers (average age 55±8.3 years old) and 40 end-stage OA patients (average age 56.5±8.9 years old) undergoing joint replacement surgery. Patients were examined before and 6 months after surgery. Pain was assessed prior to surgery using VAS index and neuropathic pain questionnaires DN4 and PainDETECT. Functional activity was evaluated by WOMAC. After surgery pain indices according to VAS of 30% and higher were considered. MMP-9 and caspase 3 protein levels were quantified by ELISA. Total RNA isolated from whole blood was used in expression studies for caspase 3; metalloproteinase (MMP)-9; cathepsins K and S genes. These were performed with quantitative real-time RT-PCR.Results:Out of 40 patients pain complaints were obtained from 9 patients (22,5%) after 6 months’ post-surgery. Prior to surgery all the examined genes were significantly upregulated in the patients who developed post-operative pain compared to healthy controls and those subjects who did not develop pain after surgery. However, no difference in the levels of the examined pain-related and functional indices in patients, who developed pain or not, was noted before surgery. ROC curve analyses confirmed significant associations (p<0.05) between expressions of the examined genes prior to surgery with the likelihood of pain development after surgery. The cut-off values for the examined gene expressions were 11.34 for cathepsin S (sensitivity of 0.89 and specificity of 0.76), 10.11 for caspase 3 (sensitivity of 0.86 and specificity of 0.65), 10.09 for cathepsin K (sensitivity of 0.86 and specificity of 0.78). Moreover, among the examined genes cathepsin S expression was the most informative predictor of postoperative pain development [AUC= 0.857, 95%CI (0.708-1.000)].Conclusion:High cathepsin S gene expression in the peripheral blood of the end-stage OA patients measured prior to joint replacement surgery could serve an important biomarker of post-operative pain development.Disclosure of Interests: :None declared

Osteoarthritis (OA) is a chronic rheumatic disease that is characterized by pain and articular cartilage degradation. Pain in OA is a main clinical symptom that limits working capacity and is one of the indications for joint replacement. However, 10-40% of patients with OA also continue to experience painful sensations after surgery.Objective: to develop a method for searching for biomarkers to predict the dynamics of pain in the postoperative period and to determine the feasibility of arthroplasty on the basis of a retrospective analysis of relative blood gene expression prior to surgery.Patients and methods. The investigators tested the blood taken from 53 OA patients (mean age, 56.5±8.9 years) before knee arthroplasty and from 26 healthy donors (mean age, 55±8.3 years). Total RNA was isolated from blood and after reverse transcription into complementary DNA was used to measure the level of relative gene expression in real-time polymerase chain reaction.Results and discussion. A retrospective analysis of the expression of genes associated with central sensitization in 53 patients with OA before arthroplasty showed that the data on the expression of tumor necrosis factor-α, interleukin-1β, cyclooxygenase-2, and transforming growth factor β1 were uninformative due to their high blood expression in all the patients. The high gene expression of cathepsin S (in 17% of the patients) and cathepsin K (in 21%) and the low gene expression of tissue inhibitor of metalloproteinases 1 (TIMP-1) (in 31%) may indicate that postoperative pain can be persistent. In contrast, no post-arthroplasty pain can be expected in 43% OA patients with low caspase 3 expression and in 23% of those with low MMP-9 one.Conclusion. Analysis of pre-arthroplasty blood gene expression in patients with OA seems to be a promising approach to predicting the dynamics of pain after surgical treatment.