Soluble inflammatory mediators of synoviocytes stimulated by monosodium urate crystals induce the production of oxidative stress, pain, and inflammation mediators in chondrocytes

Brief report[Abstract] We hypothesized that the secretion of inflammatory mediators from synoviocytes affects the chondrocyte homeostasis of articular cartilage. This study was a preliminary attempt to elucidate the molecular mechanisms by which soluble mediators obtained from activated synoviocytes induce oxidative stress and inflammation in chondrocytes. We measured the concentrations of interleukin-6 (IL-6), interleukin-8 (IL-8), monocyte chemoattractant protein-1 (MCP-1), nerve growth factor (NGF), superoxide anion (O2•-), hydrogen peroxide (H2O2), and nitric oxide (NO•) from articular human cells. First, we created a conditional basal medium by exposing synoviocytes (HS) to monosodium urate crystals (CBM). The chondrocytes were exposed to either CBM (CCM), urate crystals directly (CMSU), or remained untreated (CC) as a negative control. Data were analyzed by ANOVA tests; Bonferroni test was performed for multiple comparisons between groups. Interestingly, we observed that mediators of inflammation and oxidative stress were significantly higher in CCM than CMSU and CC groups (P<0.01). The specific concentrations were as follows: 19.85 ng/mL of IL-6, 9.79 ng/mL of IL-8, 5.17 ng/mL of NGF, and 11.91 ng/mL of MCP-1. Of note, we observed the same trend for reactive oxygen and nitrogen species (P<0.001). Soluble mediators secreted by synoviocytes after being activated with MSU crystals (as observed in individuals who present gout attacks) trigger chondrocyte activation intensifying the articular inflammatory, oxidative, and pain states that damage cartilage in OA; this damage is more severe even when compared to HC directly exposed to monosodium urate crystals. Key Points • The molecular relation between MSU depositions and cartilage damage could be mediated by pro-inflammatory soluble mediators and oxidative molecules. • The secretion of pro-inflammatory mediators by activated synoviocytes is more harmful to chondrocytes than a direct activation in the chondrocyte culture. • Under this model, there is an important imbalance in the matrix homeostasis due to changes in several chemokines, cytokines, and other factors such as NGF, as well as oxidative mediators

miR-145, miR-92a and miR-375 Show Differential Expression in Serum from Patients with Diabetic Retinopathies

Diabetic retinopathies are important disabling conditions. Micro-RNAs (miRNAs) are regulators of gene expression and diseases can change their expression. Our aim was to analyze the expression of miRNAs in serum and vitreous samples from patients with diabetic retinopathies. The following groups and number of individuals were included: proliferative diabetic retinopathy (PDR) (n = 16), diabetic macular edema (DME) (n = 17), and idiopathic epiretinal membrane (IEM) as non-diabetic controls (n = 23). The initial miRNA expression was explored using TaqMan low-density arrays (TLDAs) with subsequent validation through a quantitative polymerase chain reaction (qPCR). Target genes were identified through bioinformatic tools for enrichment analysis. The TLDAs revealed the following miRNAs with differential expression in terms of PDR vs. IEM: miR-320a-3p, miR-92a-3p, and miR-375-3p in the serum, with miR-541-5p and miR-223-5p in the vitreous samples. DME vs IEM: miR-486-5p, miR-145-5p, miR-197-3p, and miR-125b-5p in the serum, and miR-212-3p in vitreous samples. PDR vs. DME: miR-486-5p, miR-100-5p, miR-328-3p, miR-660-5p, and miR-145 in the serum and none in the vitreous samples. Validation was confirmed only for miR-145, miR-92a, and miR-375 in the serum. The relevant enriched pathways for these three validated miRNAs, miR-145, miR-92a, and miR-375 were the vascular endothelial growth factor and its receptor, hepatocyte growth factor receptor, epidermal growth factor, focal adhesion, and phosphoinositide 3-kinase. Our results support the involvement of miRNAs in the pathophysiology of diabetic retinopathies and reinforce their potential as biomarkers or therapeutic resources

The Overexpression of NALP3 Inflammasome in Knee Osteoarthritis Is Associated with Synovial Membrane Prolidase and NADPH Oxidase 2

Osteoarthritis is characterized by the presence of proinflammatory cytokines and reactive oxygen species. We aimed to clarify the role of prooxidant enzyme content at the synovial membrane level and how it correlates with the inflammatory process in patients with knee osteoarthritis (KOA). In synovial membranes from KOA patients and control group, we analyzed the protein content of prooxidant enzymes such as Nox2, xanthine oxidase (XO), and prolidase as well as the proinflammatory NALP3. Results show that protein content of prolidase and Nox2 increased 4.8- and 8.4-fold, respectively, and XO showed an increasing trend, while the NALP3 inflammasome increased 5.4-fold with respect to control group. Levels of prolidase and XO had a positive correlation between the levels of NALP3 and Nox2. By principal component analysis the protein expression pattern by study groups was evaluated. Three clusters were identified; protein expression patterns were higher for clusters two (prolidase) and three (XO and Nox2) between KOA patients and controls. Data suggest that prooxidant enzymes increase in synovial membrane of KOA patients and may contribute to the inflammatory state and degradation of the articular cartilage

Hyperlipidemic microenvironment conditionates damage mechanisms in human chondrocytes by oxidative stress

Abstract Background Currently, two pathogenic pathways describe the role of obesity in osteoarthritis (OA); one through biomechanical stress, and the other by the contribution of systemic inflammation. The aim of this study was to evaluate the effect of free fatty acids (FFA) in human chondrocytes (HC) expression of proinflammatory factors and reactive oxygen species (ROS). Methods HC were exposed to two different concentrations of FFA in order to evaluate the secretion of adipokines through cytokines immunoassays panel, quantify the protein secretion of FFA-treated chondrocytes, and fluorescent cytometry assays were performed to evaluate the reactive oxygen species (ROS) production. Results HC injury was observed at 48 h of treatment with FFA. In the FFA-treated HC the production of reactive oxygen species such as superoxide radical, hydrogen peroxide, and the reactive nitrogen species increased significantly in a at the two-dose tested (250 and 500 μM). In addition, we found an increase in the cytokine secretion of IL-6 and chemokine IL-8 in FFA-treated HC in comparison to the untreated HC. Conclusion In our in vitro model of HC, a hyperlipidemia microenvironment induces an oxidative stress state that enhances the inflammatory process mediated by adipokines secretion in HC

Additional file 5: of Monosodium urate crystals induce oxidative stress in human synoviocytes

Characterization of cell populations. Synoviocytes culture marked with anti-CD166 and anti-CD14. Each bar shows the average ± standard deviation of three independent experiments from different patients (n = 5); *P < 0.05. (DOCX 26 kb

Additional file 1: Table S1. of Monosodium urate crystals induce oxidative stress in human synoviocytes

Primers used for qRT-PCR gene analysis. (DOCX 14 kb

Additional file 4: of Monosodium urate crystals induce oxidative stress in human synoviocytes

UGDH gene expression and CD14 in synoviocytes. Synoviocytes characterized by qRT-PCR. Each bar shows the average ± standard deviation of three independent experiments from different patients (n = 5); *P < 0.05. (DOCX 25 kb