Metabolic and inflammatory profiles define phenotypes with clinical relevance in female knee osteoarthritis patients with joint effusion.

OBJECTIVES: Osteoarthritis has been the subject of abundant research in the last years with limited translation to the clinical practice, probably due to the disease's high heterogeneity. In this study, we aimed to identify different phenotypes in knee osteoarthritis (KOA) patients with joint effusion based on their metabolic and inflammatory profiles. METHODS: A non-supervised strategy based on statistical and machine learning methods was applied to 45 parameters measured on 168 female KOA patients with persistent joint effusion, consecutively recruited at our hospital after a monographic OA outpatient visit. Data comprised anthropometric and metabolic factors and a panel of systemic and local inflammatory markers. The resulting clusters were compared regarding their clinical, radiographic and ultrasound severity at baseline and their radiographic progression at two years. RESULTS: Our analyses identified four KOA inflammatory phenotypes (KOIP): a group characterized by metabolic syndrome, probably driven by body fat and obesity, and by high local and systemic inflammation (KOIP-1); a metabolically healthy phenotype with mild overall inflammation (KOIP-2); a non-metabolic phenotype with high inflammation levels (KOIP-3); and a metabolic phenotype with low inflammation and cardiovascular risk factors not associated with obesity (KOIP-4). Of interest, these groups exhibited differences regarding pain, functional disability and radiographic progression, pointing to a clinical relevance of the uncovered phenotypes. CONCLUSION: Our results support the existence of different KOA phenotypes with clinical relevance and differing pathways regarding their pathophysiology and disease evolution, which entails implications in patients' stratification, treatment tailoring and the search of novel and personalized therapies.

Synovial fluid but not plasma interleukin-8 is associated with clinical severity and inflammatory markers in knee osteoarthritis women with joint effusion.

Several cytokines and adipokines are related to clinical severity and progression in knee osteoarthritis. The aim of this study was to evaluate the associations of IL-8 with clinical severity and with local and systemic adipokines and cytokines. This is a Cross-sectional study including 115 women with symptomatic primary knee osteoarthritis with ultrasound-confirmed joint effusion. Age, symptoms duration and body mass index were collected. Radiographic severity was evaluated according to Kellgren-Lawrence. Pain and disability were assessed by Lequesne and Knee injury and Osteoarthritis Outcome Score pain, symptoms and function scales. Three inflammatory markers and five adipokines were measured by ELISA in serum and synovial fluid. Partial correlation coefficient (PCC) and corresponding 95% confidence interval were used to evaluate association. Synovial fluid IL-8 was significantly associated with clinical severity scales. After controlling for potential confounders, associations measured by a Partial Correlation Coefficient (PCC) remained essentially unaltered for Lequesne (PCC = 0.237), KOOS pain (PCC = - 0.201) and KOOS symptoms (PCC = - 0.209), KOOS function (PCC = - 0.185), although the later did not reach statistical significance. Also in synovial fluid samples, associations were found between IL-8 and TNF (PCC = 0.334), IL6 (PCC = 0.461), osteopontin (PCC = 0.575), visfatin (PCC = 0.194) and resistin (PCC = 0.182), although significance was not achieved for the later after statistical control for confounders. None of these associations were detected in serum. In conclusion, IL-8 was associated with clinical severity, inflammatory markers and adipokines in synovial fluid, but not in blood. Although the reported associations are weak to moderate in magnitude, these findings reinforce the notion that local and not systemic inflammation is more relevant to clinical severity in knee OA women with joint effusion.

Synovial Adiponectin Was More Associated with Clinical Severity than Synovial Leptin in Women with Knee Osteoarthritis.

OBJECTIVE: Different adipokines have been reported to play a role in the development, progression, and severity of knee osteoarthritis, but this association may be mediated by obesity. The aim of this study was to evaluate separately the associations of leptin and adiponectin with clinical severity and inflammatory markers in nonobese and obese women with knee osteoarthritis. DESIGN: Cross-sectional study with systematic inclusion of 115 women with symptomatic primary knee osteoarthritis. Age, physical exercise, symptoms duration, and body mass index were collected. Radiographic severity was evaluated according to Kellgren-Lawrence scale. Pain and disability were assessed by WOMAC-total, -pain, -function subscales. Two adipokines (leptin and adiponectin) and 3 inflammatory markers (TNF-α, hsCRP, and IL-6) were measured by ELISA in synovial fluid and serum. RESULTS: Synovial fluid adiponectin was associated with WOMAC pain, function, and total and with synovial fluid IL-6 in nonobese female knee osteoarthritis after controlling by confounders (partial correlation coefficient [PCC] = 0.395, 0.387, 0.427, and 0.649, respectively). Synovial fluid and serum leptin were significantly associated with IL-6 (PCC = 0.354) after controlling by confounders but associations with clinical severity and the rest of inflammatory markers were mitigated after control. CONCLUSIONS: Adiponectin in synovial fluid was associated with clinical severity and local inflammatory markers in knee osteoarthritis women, while leptin relation was attenuated when controlled by confounders.