An objective diagnosis of gout and calcium pyrophosphate deposition disease with machine learning of Raman spectra acquired in a point-of-care setting.

OBJECTIVE: Raman spectroscopy is proposed as a next-generation method for the identification of monosodium urate (MSU) and calcium pyrophosphate (CPP) crystals in synovial fluid. As the interpretation of Raman spectra requires specific expertise, the method is not directly applicable for clinicians. We developed an approach to demonstrate that the identification process can be automated with the use of machine learning techniques. The developed system is tested in a point-of-care-setting at our outpatient rheumatology department. METHODS: We collected synovial fluid samples from 446 patients with various rheumatic diseases from three centra. We analyzed all samples with our Raman spectroscope and used 246 samples for training and 200 samples for validation. Trained observers classified every Raman spectrum as MSU, CPP or else. We designed two one-against-all classifiers, one for MSU and one for CPP. These classifiers consisted of a principal component analysis model followed by a support vector machine. RESULTS: The accuracy for classification of CPP using the 2023 ACR/EULAR CPPD classification criteria was 96.0% (95% CI 92.3-98.3), while the accuracy for classification of MSU with using the 2015 ACR/EULAR gout classification criteria was 92.5% (95% CI 87.9-95.7). Overall, the accuracy for classification of pathological crystals was 88.0% (95% CI 82.7-92.2). The model was able to discriminate between pathologic crystals, artifacts, and other particles such as microplastics. CONCLUSION: We here demonstrate that potentially complex Raman spectra from clinical patient samples can be successfully classified by a machine learning approach, resulting in an objective diagnosis independent of the opinion of the medical examiner.

Noncontact Diffuse Reflectance Spectroscopy of Synovial Fluid Samples for Rapid Identification of Infections.

Severe joint infections, such as septic arthritis, require rapid diagnostic testing of the synovial fluid aspirated from joints level so that a surgical team can be assembled quickly. We present a diffuse reflectance spectroscopy (DRS) system for noncontact determination of infection. Using a light-tight syringe holder and fiber optic probe, diffusely reflected light from 475 to 655 nm was acquired from 18 patient samples through the wall of a syringe in a noncontact and sterile manner. We determined the reflectance ratios at two different wavelengths-R490/R600 and R580/R600 and found statistically significant differences (p < 0.05) in both ratios between the infected and noninfected groups. Critically, the R490/R600 and R580/R600 ratios were significantly correlated with clinical biomarkers-the white blood cell (WBC) and red blood cell (RBC) counts, respectively. This study demonstrates the potential of DRS as a rapid diagnostic tool for joint infections.

Connexin 43 Modulation in Human Chondrocytes, Osteoblasts and Cartilage Explants: Implications for Inflammatory Joint Disorders.

Connexin 43 (Cx43) is crucial for the development and homeostasis of the musculoskeletal system, where it plays multifaceted roles, including intercellular communication, transcriptional regulation and influencing osteogenesis and chondrogenesis. Here, we investigated Cx43 modulation mediated by inflammatory stimuli involved in osteoarthritis, i.e., 10 ng/mL Tumor Necrosis Factor alpha (TNFα) and/or 1 ng/mL Interleukin-1 beta (IL-1ß), in primary chondrocytes (CH) and osteoblasts (OB). Additionally, we explored the impact of synovial fluids from osteoarthritis patients in CH and cartilage explants, providing a more physio-pathological context. The effect of TNFα on Cx43 expression in cartilage explants was also assessed. TNFα downregulated Cx43 levels both in CH and OB (-73% and -32%, respectively), while IL-1ß showed inconclusive effects. The reduction in Cx43 levels was associated with a significant downregulation of the coding gene GJA1 expression in OB only (-65%). The engagement of proteasome in TNFα-induced effects, already known in CH, was also observed in OB. TNFα treatment significantly decreased Cx43 expression also in cartilage explants. Of note, Cx43 expression was halved by synovial fluid in both CH and cartilage explants. This study unveils the regulation of Cx43 in diverse musculoskeletal cell types under various stimuli and in different contexts, providing insights into its modulation in inflammatory joint disorders.

The Role of Receptor Activator of Nuclear Factor-κB Ligand/Osteoprotegerin Ratio in Synovial Fluid as a Potential Marker for Periprosthetic Osteolysis Following Total Ankle Arthroplasty.

Background: Periprosthetic osteolysis is a prevalent complication following total ankle arthroplasty (TAA), implicating various cytokines in osteoclastogenesis as pivotal in this process. This study aimed to evaluate the relationship between osteolysis and the concentrations of osteoclastogenesis-related cytokines in synovial fluid and investigate its clinical value following TAA. Methods: Synovial fluid samples from 23 ankles that underwent revision surgery for osteolysis following TAA were analyzed as the osteolysis group. As a control group, we included synovial fluid samples obtained from 23 ankles during primary TAA for osteoarthritis. The receptor activator of nuclear factor-κB ligand (RANKL)/osteoprotegerin (OPG) ratio in these samples was quantified using sandwich enzyme-linked immunosorbent assay techniques, and a bead-based multiplex immunoassay facilitated the detection of specific osteoclastogenesis-related cytokines. Results: RANKL levels averaged 487.9 pg/mL in 14 of 23 patients in the osteolysis group, with no detection in the control group's synovial fluid. Conversely, a significant reduction in OPG levels was observed in the osteolysis group (p = 0.002), resulting in a markedly higher mean RANKL/OPG ratio (0.23) relative to controls (p = 0.020). Moreover, the osteolysis group had increased concentrations of various osteoclastogenesis-related cytokines (tumor necrosis factor-α, interleukin [IL]-1ß, IL-6, IL-8, IP-10, and monocyte chemotactic protein-1) in the synovial fluid relative to the control group. Conclusions: Our results demonstrated that periprosthetic osteolysis was associated with osteoclastogenesis activation through an elevated RANKL/OPG ratio following TAA. We assume that RANKL and other osteoclastogenesis-related cytokines in the synovial fluid have clinical value as a potential marker for the development and progression of osteolysis following TAA.

Fcγ-receptor-IIIA bioactivity of circulating and synovial immune complexes in rheumatoid arthritis.

OBJECTIVE: Previous technical limitations prevented the proof of Fcγ-receptor (FcγR)-activation by soluble immune complexes (sICs) in patients. FcγRIIIa (CD16) is a risk factor in rheumatoid arthritis (RA). We aimed at determining the presence of CD16-activating sICs in RA and control diseases. METHODS: Sera from an exploratory cohort (n=50 patients with RA) and a validation cohort (n=106 patients with RA, 20 patients with psoriasis arthritis (PsA), 22 patients with systemic lupus erythematosus (SLE) and 31 healthy controls) were analysed using a new reporter cell assay. Additionally, 26 synovial fluid samples were analysed, including paired serum/synovial samples. RESULTS: For the first time using a reliable and sensitive functional assay, the presence of sICs in RA sera was confirmed. sICs possess an intrinsic capacity to activate CD16 and can be found in both synovial fluid and in blood. In low experimental dilutions, circulating sICs were also detected in a subset of healthy people and in PsA. However, we report a significantly increased frequency of bioactive circulating sICs in RA. While the bioactivity of circulating sICs was low and did not correlate with clinical parameters, synovial sICs were highly bioactive and correlated with serum autoantibody levels. Receiver operator curves indicated that sICs bioactivity in synovial fluid could be used to discriminate immune complex-associated arthritis from non-associated forms. Finally, circulating sICs were more frequently found in SLE than in RA. The degree of CD16 bioactivity showed strong donor-dependent differences, especially in SLE. CONCLUSIONS: RA is characterised by the presence of circulating and synovial sICs that can engage and activate CD16.

(Chemical) Roles of HOCl in Rheumatic Diseases.

Chronic rheumatic diseases such as rheumatoid arthritis (RA) are characterized by a dysregulated immune response and persistent inflammation. The large number of neutrophilic granulocytes in the synovial fluid (SF) from RA patients leads to elevated enzyme activities, for example, from myeloperoxidase (MPO) and elastase. Hypochlorous acid (HOCl), as the most important MPO-derived product, is a strong reactive oxygen species (ROS) and known to be involved in the processes of cartilage destruction (particularly regarding the glycosaminoglycans). This review will discuss open questions about the contribution of HOCl in RA in order to improve the understanding of oxidative tissue damaging. First, the (chemical) composition of articular cartilage and SF and the mechanisms of cartilage degradation will be discussed. Afterwards, the products released by neutrophils during inflammation will be summarized and their effects towards the individual, most abundant cartilage compounds (collagen, proteoglycans) and selected cellular components (lipids, DNA) discussed. New developments about neutrophil extracellular traps (NETs) and the use of antioxidants as drugs will be outlined, too. Finally, we will try to estimate the effects induced by these different agents and their contributions in RA.

ELIXCYTE®, an Allogenic Adipose-Derived Stem Cell Product, Mitigates Osteoarthritis by Reducing Inflammation and Preventing Cartilage Degradation In Vitro.

Adipose-derived stem cells (ADSCs) comprise a promising therapy for osteoarthritis (OA). The therapeutic potential of ELIXCYTE®, an allogeneic human ADSC (hADSC) product, was demonstrated in a phase I/II OA clinical trial. However, the exact mechanism underlying such effects is not clear. Moreover, studies suggest that interleukin-11 (IL-11) has anti-inflammatory, tissue-regenerative, and immune-regulatory functions. Our aim was to unravel the mechanism associated with the therapeutic effects of ELIXCYTE® on OA and its relationship with IL-11. We cocultured ELIXCYTE® with normal human articular chondrocytes (NHACs) in synovial fluid obtained from individuals with OA (OA-SF) to investigate its effect on chondrocyte matrix synthesis and degradation and inflammation by assessing gene expression and cytokine levels. NHACs exposed to OA-SF exhibited increased MMP13 expression. However, coculturing ELIXCYTE® with chondrocytes in OA-SF reduced MMP13 expression in chondrocytes and downregulated PTGS2 and FGF2 expression in ELIXCYTE®. ELIXCYTE® treatment elevated anti-inflammatory cytokine (IL-1RA, IL-10, and IL-13) levels, and the reduction in MMP13 was positively correlated with IL-11 concentrations in OA-SF. These findings indicate that IL-11 in OA-SF might serve as a predictive biomarker for the ELIXCYTE® treatment response in OA, emphasizing the therapeutic potential of ELIXCYTE® to mitigate OA progression and provide insights into its immunomodulatory effects.

A major functional role of synovial fluid is to reduce the rate of cartilage fatigue failure under cyclical compressive loading.

OBJECTIVE: Based on our recent study, which showed that cartilage fatigue failure in reciprocating sliding contact results from cyclical compressive forces, not from cyclical frictional forces, we hypothesize that a major functional role for synovial fluid (SF) is to reduce the rate of articular cartilage fatigue failure from cyclical compressive loading. DESIGN: The rate of cartilage fatigue failure due to repetitive compressive loading was measured by sliding a glass lens against an immature bovine cartilage tibial plateau strip immersed in mature bovine SF, phosphate-buffered saline (PBS), or SF/PBS dilutions (50% SF and 25% SF; n = 8 for all four bath conditions). After 24 h of reciprocating sliding (5400 cycles), samples were visually assessed, and if damage was observed, the test was terminated; otherwise, testing was continued for 72 h (16,200 cycles), with solution refreshed daily. RESULTS: All eight samples in the PBS group exhibited physical damage after 24 h, with an average final surface roughness of Rq= 0.210 ± 0.067 mm. The SF group showed no damage after 24 h; however, two of eight samples became damaged after 72 h, producing a significantly lower average surface roughness than the PBS group (Rq=0.059 ± 0.030 mm; p < 10-4). For the remaining groups, at 72 h, one of eight samples was damaged in the 50% SF group, and five of eight samples were damaged in the 25% SF group. CONCLUSIONS: The results strongly support our hypothesis, showing that decreased amounts of SF in the testing bath produce increased rates of fatigue failure in cartilage that was subjected to reciprocating sliding contact.

Multiplex PCR in septic arthritis and periprosthetic joint infections microorganism identification: Results from the application of a new molecular testing diagnostic algorithm.

Purpose: Pathogen identification is key in the treatment of septic arthritis (SA) and periprosthetic joint infections (PJI). This study evaluates the outcome of the application of a new, score-based SA and PJI diagnostic algorithm, which includes the execution of molecular testing on synovial fluid. Methods: A score-based diagnostic algorithm, which includes serologic and synovial fluid markers determination using multiplex PCR (mPCR) and Next Generation Sequencing (NGS) molecular testing, has been applied to a consecutive series of patients with clinically suspected SA or PJI. Patients with a score ≥6 underwent synovial fluid molecular testing, together with traditional culture, to identify the pathogen and its genetically determined antibiotic resistance. Results: One hundred and seventeen joints in 117 patients (62.5% women; average age 73 years) met the criteria for possible SA/PJI. The affected joint was the knee in 87.5% (joint replacement 66.5%; native joint 21%) and the hip in 12.5% (all replaced joints). 43/117 patients (36.7%) were ultimately diagnosed with SA/PJI. Among the various testing technologies applied, mPCR was the main determinant for pathogen identification in 63%, standard culture in 26%, and mNGS in 11%. Staphylococcus aureus and Enterococcus faecalis were the top two microorganisms identified by mPCR, while Staphylococcus epidermidis was the prevalent organism identified by NGS. mPCR detected the presence/absence of the genetically determined antibiotic resistance of all identified microorganisms. The average timeframe for pathogen identification was 3.13 h for mPCR, 4.5 days for culture, and 3.2 days for NGS. Conclusions: Molecular diagnostic technologies represent an innovative screening for fast microorganism identification when a joint infection is clinically suspected. Level of Evidence: Level IV, case series.

Infrared thermogram image guided discontinuous appearances of hyaluronic acid for classification of arthritic knee joints.

The liveliness of a human potentially depends on his/her smooth movability. To accomplish the work of daily life, the joints of the body need to be healthy. However, the occurrence of Rheumatoid arthritis and Osteoarthritis has a significant prevalence towards the immovability of humankind. Rheumatoid arthritis (RA) and Osteoarthritis (OA) mostly affect the joints of the hand and knee which result in lifelong pain, inability to climb, walk, etc. In the early stages, these diseases attack the synovial membrane and synovial fluid, and further it destroys the soft tissues and bone structure. By early diagnosis, we can start the treatment in the early stage which may cure these diseases with such extreme consequences. As per clinical studies of previous literature, it is observed that synovial fluid imbalance appears in the early stage of such diseases and Hyaluronic Acid (HA) concentration also decreases for that. Therefore, estimation of HA is a significant key to arthritis disease classification and grading. In this paper, we proposed a hybrid framework for classification of arthritic knee joints based on the analysis of the discontinuous appearances of the HA concentration using infrared imaging technology. To meet up the specific necessities, firstly we have proposed a modified K-Means clustering algorithm for extraction of the region of interest (ROI) i.e., the knee joint surface. Secondly, a mathematical formulation is proposed to calculate the concentration of HA from the segmented ROIs. This experimental process was implemented on the publicly available IR (Infrared) Knee Joint Dataset and for further evaluation of the novelty of mathematical formulation, we have extended the proposed work to the classification of healthy and arthritis affected knee joints depending on significant discriminative characteristics of the HA concentration with respect to the existing significant imaging features. Experimental results and analysis demonstrates that concentration of HA has the dominant potential for classifying healthy and arthritic knee joints using infrared holistic images. Our experimental analysis reveals that estimation and combination of the HA concentration features with conventional handcrafted and deep features increases the classification performance with an average accuracy of 91% and 97.22% respectively as compared to the each individual feature sets.

Lipidome profiling of neutrophil-derived extracellular vesicles unveils their contribution to the ensemble of synovial fluid-derived extracellular vesicles during joint inflammation.

The molecular signature of cell-derived extracellular vesicles (EVs) from synovial fluid (SF) offers insights into the cells and molecular processes associated with joint disorders and can be exploited to define biomarkers. The EV-signature is determined by cargo molecules and the lesser-studied lipid bilayer. We here investigated the lipidome of SF-EVs in inflamed joints derived from Rheumatoid Arthritis (RA) and Spondyloarthritis (SpA) patients, two autoimmune-driven joint diseases, and compared these signatures to the lipid profile of equine SF-EVs obtained during induced acute synovitis. Since neutrophils are primary SF-infiltrating cells during these inflammatory joint diseases, we also analyzed how inflammatory stimuli alter the lipidomic profile of human and equine neutrophil-derived EVs (nEVs) in vitro and how these signatures relate to the lipidome signatures of SF-EVs from inflamed joints. We identified neutrophil stimulation intensity-dependent changes in the lipidomic profile of nEVs with elevated presence of dihexosylceramide (lactosylceramide), phosphatidylserine, and phosphatidylethanolamine ether-linked lipid classes in human nEVs upon full neutrophil activation. In horses, levels of monohexosylceramide (glucosylceramide) increased instead of dihexosylceramide, indicating species-specific differences. The lipid profiles of RA and SpA SF-EVs were relatively similar and showed a relative resemblance with stimulated human nEVs. Similarly, the lipidome of equine synovitis-derived SF-EVs closer resembled the one of stimulated equine nEVs. Hence, lipidome profiling can provide insights into the contribution of nEVs to the heterogeneous pool of SF-EVs, deepening our understanding of inflammatory joint diseases and revealing molecular changes in joint homeostasis, which can lead to the development of more precise disease diagnosis and treatment strategies.

A novel inhibitory pathway of synovial inflammation exerted by glucocorticoids and tumor necrosis factor inhibitors via lymphocyte activation gene-3 up-regulation: an ex-vivo study.

OBJECTIVE: To investigate the impact of glucocorticoids (GCs) and anti-rheumatic drugs on the lymphocyte activation gene-3 (LAG-3) and on programmed cell death-1 (PD-1) expression on synovial and peripheral cells ex-vivo. METHODS: Synovial fluid mononuclear cells (SFMCs) from psoriatic arthritis (PsA, n = 26) and rheumatoid arthritis (RA, n = 13) patients, SFCs from osteoarthritis (OA, n = 5) patients and peripheral blood mononuclear cells (PBMCs) of healthy donors (n = 14) were co-cultured with GCs, glucocorticoid receptor antagonist RU486, methotrexate (MTX) and biologics. LAG-3 and PD-1 expressions on immune subsets were analyzed by flow cytometry. RESULTS: GCs in PsA inhibited SFMCs growth vs medium (2.3 ± 0.4X105  vs 5.3 ± 0.7X105, respectively, p < 0.01) and markedly upregulated CD14+LAG-3+ cells (11.7 ± 2.4% vs 0.8 ± 0.3%, p < 0.0001, respectively), but not CD3+LAG-3+ and CD14+PD-1+ cells. MTX had no effect on CD14+LAG-3+ cells (0.7 ± 0.3%). The TNFi inhibitors, infliximab (IFX) and etanercept, but not IL-12/23i, upregulated CD14+LAG-3+ cells vs medium (2.0 ± 0.6% and 1.6 ± 0.4% vs 0.5 ± 0.1%, p < 0.03, respectively). SFMCs growth inhibition in both PsA and RA correlated with CD14+LAG-3+ cell upregulation (r = 0.53, p = 0.03). RU486 inhibited GC-induced CD14+LAG-3+ cell up-regulation in a dose-dependent manner compared with GC alone (5µM 5.3 ± 1.2% and 50µM 1.3 ± 0.5% vs 7.0 ± 1.4%, p < 0.003), but had no significant effect on CD14+LAG-3+ cells co-cultured with IFX. GCs in healthy donors' PBMCs upregulated the immune subsets CD3+LAG-3+, CD14+LAG-3+ and CD14+PD-1+ cells. CONCLUSION: This study proposes a novel regulatory mechanism of GCs and of TNFi mediated by LAG-3 upregulation in synovial monocytes and PBMCs. LAG-3 modulation may be a promising target for development of novel therapies for inflammatory arthritis.

Diagnostic Performance of a Molecular Assay in Synovial Fluid Targeting Dominant Prosthetic Joint Infection Pathogens.

Prosthetic joint infection (PJI) is one of the most serious complications of joint replacement surgery among orthopedic surgeries and occurs in 1 to 2% of primary surgeries. Additionally, the cause of PJIs is mostly bacteria from the Staphylococcus species, accounting for more than 98%, while fungi cause PJIs in only 1 to 2% of cases and can be difficult to manage. The current gold-standard microbiological method of culturing synovial fluid is time-consuming and produces false-negative and -positive results. This study aimed to identify a novel, accurate, and convenient molecular diagnostic method. The DreamDX primer-hydrolysis probe set was designed for the pan-bacterial and pan-fungal detection of DNA from pathogens that cause PJIs. The sensitivity and specificity of DreamDX primer-hydrolysis probes were 88.89% (95% CI, 56.50-99.43%) and 97.62% (95% CI, 87.68-99.88%), respectively, compared with the microbiological method of culturing synovial fluid, and receiver operating characteristic (ROC) area under the curve (AUC) was 0.9974 (*** p < 0.0001). It could be concluded that the DreamDX primer-hydrolysis probes have outstanding potential as a molecular diagnostic method for identifying the causative agents of PJIs, and that host inflammatory markers are useful as adjuvants in the diagnosis of PJIs.

Could synovial fluid be a useful substrate for the forensic analysis of diatoms?

To date, synovial fluid has not been the subject of targeted analysis as a possible substrate to search for the presence of diatoms in the forensic context of drowning. However, its unique characteristics of production and isolation from the external environment could make it suitable for this purpose, similar to what has already been demonstrated in the literature for vitreous humor. By considering this, synovial fluid was analyzed in a specific case that came to our attention, where the coexisting signs of polytrauma and drowning were documented during autopsy, demonstrating a period of vitality during immersion. After a thin smear of the supernatant was obtained from the centrifugation of the synovial fluid sample, diatoms were successfully detected, consistent with those found in other organs and the water of the canal. The detection of diatoms in the synovial fluid was an objective finding, but its generalizability is limited because this was a pilot application. However, in cases where death by drowning is suspected and the body has multiple areas breached by trauma, the technique of analyzing diatoms in the synovial fluid could have great potential. Therefore, it is appropriate to further explore this technique in order to obtain more forensic evidence in such a setting.

Identification of autoantibodies against PsoP27 in synovial fluid derived from psoriatic arthritis and rheumatoid arthritis patients.

PsoP27 is an antigen expressed in psoriatic lesions. It plays an inflammatory role in psoriasis. This study objective was to characterize antibodies (Abs) against PsoP27 in patients with psoriatic arthritis (PsA) and rheumatoid arthritis (RA). Levels of Abs against native and citrullinated PsoP27 in PsA and RA patients' synovial fluid (SF) and sera were determined by ELISA. SF of osteoarthritis (OA) patients and sera of healthy donors were used as controls. Levels of Abs against PsoP27 were correlated with disease activity scores. Abs against native and citrullinated PsoP27 levels in SF of PsA (n = 48; 0.38 ± 0.03 and 0.44 ± 0.04, respectively) and RA (n = 22; 0.57 ± 0.1 and 0.62 ± 0.09, respectively) were significantly higher than in OA patients (n = 23; 0.14 ± 0.01 and 0.15 ± 0.01, respectively) (p < .0001). For both Abs, there were no significant differences between their level in PsA and RA patients. There was no difference in the level of Abs against citrullinated PsoP27 in SF of seronegative versus seropositive RA patients. Levels of Abs against both native and citrullinated PsoP27 in the SF and level of systemic C-reactive protein in PsA correlated positively, while in RA there were no significant correlations with disease activity scores. No differences in level of Abs against PsoP27 were found in the sera of all three study groups. Abs against native and citrullinated PsoP27 are present in PsA and RA SF but not in those of OA patients, suggesting a potential role of those Abs in inflammatory joint diseases.

Exploring the Early Molecular Pathogenesis of Osteoarthritis Using Differential Network Analysis of Human Synovial Fluid.

The molecular mechanisms that drive the onset and development of osteoarthritis (OA) remain largely unknown. In this exploratory study, we used a proteomic platform (SOMAscan assay) to measure the relative abundance of more than 6000 proteins in synovial fluid (SF) from knees of human donors with healthy or mildly degenerated tissues, and knees with late-stage OA from patients undergoing knee replacement surgery. Using a linear mixed effects model, we estimated the differential abundance of 6251 proteins between the three groups. We found 583 proteins upregulated in the late-stage OA, including MMP1, collagenase 3 and interleukin-6. Further, we selected 760 proteins (800 aptamers) based on absolute fold changes between the healthy and mild degeneration groups. To those, we applied Gaussian Graphical Models (GGMs) to analyze the conditional dependence of proteins and to identify key proteins and subnetworks involved in early OA pathogenesis. After regularization and stability selection, we identified 102 proteins involved in GGM networks. Notably, network complexity was lost in the protein graph for mild degeneration when compared to controls, suggesting a disruption in the regular protein interplay. Furthermore, among our main findings were several downregulated (in mild degeneration versus healthy) proteins with unique interactions in the healthy group, one of which, SLCO5A1, has not previously been associated with OA. Our results suggest that this protein is important for healthy joint function. Further, our data suggests that SF proteomics, combined with GGMs, can reveal novel insights into the molecular pathogenesis and identification of biomarker candidates for early-stage OA.

Increase in gonococcal arthritis in Madrid, Spain, 2022-2023.

In recent years, there has been an increase in Neisseria gonorrhoeae infections in Europe and Spain. Disseminated gonococcal infection is an uncommon clinical presentation that includes gonococcal arthritis. Improved antibiotic treatment has reduced the incidence of gonococcal arthritis. However, the increase in gonococcal infections may have increased the frequency of this clinical entity in recent times. We report five cases of gonococcal arthritis in patients in a tertiary-care hospital in the northern area of Madrid (Spain) from October 2022 to October 2023. Major cases occurred in male patients with unprotected sex and polyarticular symptoms requiring hospital admission and treatment with ceftriaxone and cefixime. The use of molecular techniques has allowed the detection of a greater number of culture-negative cases of gonococcal arthritis, as well as the detection of mutations associated with resistance to fluoroquinolone for switching to oral treatment.

Identification of plasma and urinary inflammatory markers in severe knee osteoarthritis: Relations with synovial fluid markers.

BACKGROUND: This study aimed to identify plasma and urinary cytokines as potential biomarkers for severe knee osteoarthritis (OA). It also investigated associations between these cytokines and cartilage markers, as well as their connections with synovial fluid (SF) markers. METHODS: Samples of plasma, urine, and SF were obtained from patients (n = 40) undergoing total knee arthroplasty (TKA) or unicompartmental knee arthroplasty (UKA) due to severe knee OA. Control samples of plasma and urine were collected from non-OA individuals (n = 15). We used a Luminex immunoassay for the simultaneous measurement of 19 cytokines, MMP-1, and MMP-3 levels. COMP, CTX-II, and hyaluronan (HA) levels were quantified using enzyme-linked immunosorbent assay (ELISA) kits. Receiver operating characteristic (ROC) curves were utilized to analyze each biomarker's performance. Correlations among these biomarkers were evaluated via Spearman's correlation. RESULTS: The levels of plasma (p)CCL11, pCXCL16, pIL-8, pIL-15, pHA, urinary (u)CCL2, uCCL11, uCCL19, uCXCL16, uIL-1ß, uIL-6, uIL-8, uIL-12p70, uIL-15, uIL-33, uMMP-3, uHA, uCTX-II, and uCOMP were significantly elevated in individuals with severe knee OA. Notably, specific correlations were observed between the plasma/urine biomarkers and SF biomarkers: pCCL11 with sfHA (r = 0.56) and sfTNF-α (r = 0.58), pIL-15 with sfCCL19 (r = 0.43) and sfCCL20 (r = 0.44), and uCCL19 with sfCCL11 (r = 0.45) and sfIL-33 (r = 0.51). Positive correlations were also observed between uCCL11 and its corresponding sfCCL11(r = 0.49), as well as between sfCCL11 and other cytokines, namely sfCCL4, sfCCL19, sfCCL20, sfIL-33, and sfTNF-α (r = 0.46-0.63). CONCLUSION: This study provides an extensive profile of systemic inflammatory mediators in plasma of knee OA and identified four inflammatory markers (pCCL11, pIL-15, uCCL11, and uCCL19) reflecting joint inflammation.