Inflammatory synovial fluid microenvironment drives primary human chondrocytes to actively take part in inflammatory joint diseases

Direct comparison of non-osteoarthritic and osteoarthritic synovial fluid-induced intracellular chondrocyte signaling and phenotype changes

OBJECTIVE

Since the joint microenvironment and tissue homeostasis are highly dependent on synovial fluid, we aimed to compare the essential chondrocyte signaling signatures of non-osteoarthritic vs end-stage osteoarthritic knee synovial fluid. Moreover, we determined the phenotypic consequence of the distinct signaling patterns on articular chondrocytes.

METHODS

Protein profiling of synovial fluid was performed using antibody arrays. Chondrocyte signaling and phenotypic changes induced by non-osteoarthritic and osteoarthritic synovial fluid were analyzed using a phospho-kinase array, luciferase-based transcription factor activity assays, and RT-qPCR. The origin of osteoarthritic synovial fluid signaling was evaluated by comparing the signaling responses of conditioned media from cartilage, synovium, infrapatellar fat pad and meniscus. Osteoarthritic synovial fluid induced pathway-phenotype relationships were evaluated using pharmacological inhibitors.

RESULTS

Compared to non-osteoarthritic synovial fluid, osteoarthritic synovial fluid was enriched in cytokines, chemokines and growth factors that provoked differential MAPK, AKT, NFκB and cell cycle signaling in chondrocytes. Functional pathway analysis confirmed increased activity of these signaling events upon osteoarthritic synovial fluid stimulation. Tissue secretomes of osteoarthritic cartilage, synovium, infrapatellar fat pad and meniscus activated several inflammatory signaling routes. Furthermore, the distinct pathway signatures of osteoarthritic synovial fluid led to accelerated chondrocyte dedifferentiation via MAPK/ERK signaling, increased chondrocyte fibrosis through MAPK/JNK and PI₃K/AKT activation, an elevated inflammatory response mediated by cPKC/NFκB, production of extracellular matrix-degrading enzymes by MAPK/p38 and PI₃K/AKT routes, and enabling of chondrocyte proliferation.

CONCLUSION

This study provides the first mechanistic comparison between non-osteoarthritic and osteoarthritic synovial fluid, highlighting MAPKs, cPKC/NFκB and PI₃K/AKT as crucial OA-associated intracellular signaling routes.

Elevated expression of TAM receptor tyrosine kinase in synovial fluid and synovial tissue of rheumatoid arthritis

To investigate the expression and roles of TAM (Tyro3/Axl/Mer) receptor tyrosine kinases (TK) in synovial fluid and synovial tissue of patients with rheumatoid arthritis (RA). The expression of TAM TKs in the synovial fluid and synovial tissues of RA and osteoarthritis (OA) patients was measured by ELISA and immunohistochemistry. The relationships between soluble TAM TKs (sTAM TKs) levels and the clinical features, laboratory parameters and disease activity were analyzed in RA. The concentrations of sTAM TK in the synovial fluids of RA patients were increased in comparison to those of OA patients. Compared with OA patients, the expression of membrane Tyro3 TK (mTyro3 TK) and mMer TK in RA patient synovial tissue were significantly increased, which may partly explain the possible mechanism of elevated levels of sTAM TK in RA patient synovial fluid. sAxl TK levels were decreased in RA patients under sulfasalazine treatment and elevated in patients under Iguratimod treatment. Furthermore, sTyro3 TK levels were positively correlated with erythrocyte sedimentation rate (ESR) and negatively correlated with white blood cells (WBCs), red blood cells (RBCs), and hemoglobin (HB) in RA patients. The levels of sMer TK were positively associated with disease duration and rheumatoid factor (RF) and negatively correlated with HB, complement 3 (C3), and C4. Taken together, TAM TKs might be involved in RA synovial tissue inflammation.

Synovial Fluid Regulates the Gene Expression of a Pattern of microRNA via the NF-κB Pathway: An In Vitro Study on Human Osteoarthritic Chondrocytes

Synovial fluid (SF) represents the primary source of nutrients of articular cartilage and is implicated in maintaining cartilage metabolism. We investigated the effects of SF, from patients with osteoarthritis (OA), rheumatoid arthritis (RA), and controls, on a pattern of microRNA (miRNA) in human OA chondrocytes. Cells were stimulated with 50% or 100% SF for 24 h and 48 h. Apoptosis and superoxide anion production were detected by cytometry; miRNA (34a, 146a, 155, 181a), cytokines, metalloproteinases (MMPs), type II collagen (Col2a1), antioxidant enzymes, B-cell lymphoma (BCL)2, and nuclear factor (NF)-κB by real-time PCR. The implication of the NF-κB pathway was assessed by the use of NF-κB inhibitor (BAY-11-7082). RA and OA SF up-regulated miR-34a, -146a, -155, -181a, interleukin (IL)-1β, IL-6, tumor necrosis factor (TNF)-α, MMP-1, MMP-13, and ADAMTs-5 gene expression, while it down-regulated Col2a1. Pathological SF also induced apoptosis, reduced viability, and decreased BCL2 mRNA, whereas it increased superoxide anions, the expression of antioxidant enzymes, p65 and p50 NF-κB. Opposite and positive results were obtained with 100% control SF. Pre-incubation with BAY-11-7082 counteracted SF effects on miRNA. We highlight the role of the SF microenvironment in regulating some miRNA involved in inflammation and cartilage degradation during OA and RA, via the NF-κB pathway.

Apoptosis, Autophagy, NETosis, Necroptosis, and Pyroptosis Mediated Programmed Cell Death as Targets for Innovative Therapy in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory joint disease that can lead to clinical manifestations of systemic diseases. Its leading features include chronic synovial inflammation and degeneration of the bones and joints. In the past decades, multiple susceptibilities for rheumatoid arthritis have been identified along with the development of a remarkable variety of drugs for its treatment; which include analgesics, glucocorticoids, nonsteroidal anti-inflammatory medications (NSAIDs), disease-modifying anti-rheumatic drugs (DMARDs), and biologic response modifiers (bDMARDs). Despite the existence of many clinical treatment options, the prognosis of some patients remains poor due to complex mechanism of the disease. Programmed cell death (PCD) has been extensively studied and ascertained to be one of the essential pathological mechanisms of RA. Its dysregulation in various associated cell types contributes to the development of RA. In this review, we summarize the role of apoptosis, cell death-associated neutrophil extracellular trap formation, necroptosis, pyroptosis, and autophagy in the pathophysiology of RA to provide a theoretical reference and insightful direction to the discovery and development of novel therapeutic targets for RA.

Influence of Cellular Microenvironment on Human Articular Chondrocyte Cell Signaling

OBJECTIVE

Alteration of the cellular microenvironment may influence the intra- and intercellular communication and contribute to cartilage injury and repair. The purpose of this study was to investigate how matrix elasticity/stiffness affects chondrogenic activities, including cell survival, phenotypic expression, and the release of both pro- and anti-inflammatory cytokines.

DESIGN

Human articular chondrocytes (HACs) cultured on traditional 2-dimensional (2D) plastic surfaces were compared with those cultured within 3D hydrogel matrices of varying stiffness. Chondrogenic proliferation, differentiation, and the expression of pro- and anti-inflammatory cytokines were evaluated. Both interleukin-1-beta (IL-1β) and human synovial fluid-derived cells (hSFCs) were introduced to study the effects of matrix stiffness on chondrocyte response.

RESULTS

Cells demonstrated the most robust chondrogenic differentiation and secreted the least pro-inflammatory cytokines when the matrix stiffness was close to their native microenvironment. The IL-1β effects were attenuated when HACs were co-cultured with hSFCs.

CONCLUSION

Modifying the matrix stiffness to mimic the native cartilage microenvironment not only optimized chondrogenic expression but also was essential for the regulation of physiological homeostasis. This study proposed a new toolkit to study cell-molecule, cell-cell, and cell-matrix influence on cartilage physiology.

lncRNA GAS5 suppresses rheumatoid arthritis by inhibiting miR-361-5p and increasing PDK4

Rheumatoid arthritis (RA) is an inflammatory disease that causes hyperplasia of synovial tissue and cartilage destruction. This research was to investigate the effects of lncRNA GAS5/miR-361-5p/PDK4 on rheumatoid arthritis. By qRT-PCR, GAS5 and PDK4 were found to be overexpressed in synovial tissue, fibroblast-like synoviocytes of RA patients and LPS-induced chondrocytes, while the miR-361-5p expression was significantly reduced. GAS5 overexpression resulted in a decrease in the proliferation and Bcl-2 protein expression, and an increase in the Bax protein level. On the contrary, miR-361-5p sponged by GAS5 could accelerate chondrocyte proliferation, inhibit apoptosis. PDK4 targeted by miR-361-5p could inhibit RA, and partially eliminated the effect of miR-361-5p on RA. Our study suggested that GAS5 suppressed RA by competitively adsorbing miR-361-5p to modulate PDK4 expression.

Inflammatory microenvironment-targeted nanotherapies

Inflammatory microenvironments (IMEs) are common pathological characteristics and drive the development of multiple chronic diseases. Thus, IME-targeted therapies exhibit potential for the treatment of inflammatory diseases. Nanoplatforms have significant advantages in improving the efficiency of anti-inflammatory treatments. Owing to their improved therapeutic effects and reduced side effects, IME-targeted nanotherapies have recently drawn interest from the research community. This review introduces IMEs and discusses the application of IME-targeted nanotherapies for inflammatory diseases. The development of rational targeting strategies tailored to IMEs in damaged tissues can help promote therapies for chronic diseases.

Macrophage migration inhibitory factor may play a protective role in osteoarthritis

BACKGROUND

Osteoarthritis (OA) is the most prevalent form of arthritis and the major cause of disability and overall diminution of quality of life in the elderly population. Currently there is no cure for OA, partly due to the large gaps in our understanding of its underlying molecular and cellular mechanisms. Macrophage migration inhibitory factor (MIF) is a procytokine that mediates pleiotropic inflammatory effects in inflammatory diseases such as rheumatoid arthritis (RA) and ankylosing spondylitis (AS). However, data on the role of MIF in OA is limited with conflicting results. We undertook this study to investigate the role of MIF in OA by examining MIF genotype, mRNA expression, and protein levels in the Newfoundland Osteoarthritis Study.

METHODS

One hundred nineteen end-stage knee/hip OA patients, 16 RA patients, and 113 healthy controls were included in the study. Two polymorphisms in the MIF gene, rs755622, and -794 CATT_5-8, were genotyped using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and PCR followed by automated capillary electrophoresis, respectively. MIF mRNA levels in articular cartilage and subchondral bone were measured by quantitative polymerase chain reaction. Plasma concentrations of MIF, tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and interleukin-1 beta (IL-1β) were measured by enzyme-linked immunosorbent assay.

RESULTS

rs755622 and -794 CATT_5-8 genotypes were not associated with MIF mRNA or protein levels or OA (all p ≥ 0.19). MIF mRNA level in cartilage was lower in OA patients than in controls (p = 0.028) and RA patients (p = 0.004), while the levels in bone were comparable between OA patients and controls (p = 0.165). MIF protein level in plasma was lower in OA patients than in controls (p = 3.01 × 10^-10), while the levels of TNF-α, IL-6 and IL-1β in plasma were all significantly higher in OA patients than in controls (all p ≤ 0.0007). Multivariable logistic regression showed lower MIF and higher IL-1β protein levels in plasma were independently associated with OA (OR per SD increase = 0.10 and 8.08; 95% CI = 0.04-0.19 and 4.42-16.82, respectively), but TNF-α and IL-6 became non-significant.

CONCLUSIONS

Reduced MIF mRNA and protein expression in OA patients suggested MIF might have a protective role in OA and could serve as a biomarker to differentiate OA from other joint disorders.

Damage control orthopaedics in polytraumatized patients- current concepts

The principles of fracture management in patients with multiple injuries continue to be of crucial importance. Early treatment of unstable polytraumatized patients with head, chest, abdomen or pelvic injuries, with blood loss followed by immediate fracture fixation (Early Total Care -ETC) may be associated with secondary life threatening posttraumatic systemic inflammatory response syndrome (SIRS). Development of SIRS is typically a function of the type and severity of the initial injury (the "first hit"). Immediate Fracture fixation, using reamed nails or plates, in such unstable patients with multiple injuries is subsequently defined as the "second hit" and may be associated with development of acute respiratory distress syndrome (ARDS) and multiple organ failure (MOF), with relatively high morbidity and mortality. The other alternative for long bone fracture fixation in unstable polytraumatized patients is based on immediate treatment of life threatening conditions related to the injuries, followed by the initial use of minimally invasive modular external frames for long bone fractures and is called Damage Control Orthopedics (DCO) and is widely accepted. In order to refine the DCO concept and to avoid an overuse of external fixation, the "Safe Definitive Surgery" (SDS) concept has been introduced, which is a dynamic synthesis of both strategies (ETC and DCO). The SDS strategy employs clinical parameters and includes repeated assessment of patients. The following paper is going to summarize historical backgrounds and recent concepts in treatment of polytraumatized patients.

Rheumatoid arthritis synovial microenvironment induces metabolic and functional adaptations in dendritic cells

Rheumatoid arthritis (RA) is a chronic autoimmune disease which causes degradation of cartilage and bone. It is well appreciated that the pathogenic hallmark of RA is the mass influx of inflammatory cells into the joint. However, the role that dendritic cells (DC) may play in this inflammatory milieu is still relatively unexplored. Moreover, the contribution this unique synovial microenvironment has on DC maturation is still unknown. Using monocyte-derived DC (MoDC), we established an in-vitro model to recapitulate the synovial microenvironment to explore DC maturation. MoDC treated with conditioned media from ex-vivo synovial tissue biopsy cultures [explant-conditioned media (ECM)] have increased expression of proinflammatory cytokines, chemokines and adhesion molecules. ECM DC have increased expression of CD83 and CC-chemokine receptor (CCR)7 and decreased expression of CCR5 and phagocytic capacity, suggestive of heightened DC maturation. ECM-induced maturation is concomitant with altered cellular bioenergetics, whereby increased expression of glycolytic genes and increased glucose uptake are observed in ECM DC. Collectively, this results in a metabolic shift in DC metabolism in favour of glycolysis. These adaptations are in-part mediated via signal transducer and activator of transcription-3 (STAT-3), as demonstrated by decreased expression of proinflammatory cytokines and glycolytic genes in ECM DC in response to STAT-3 inhibition. Finally, to translate these data to a more in-vivo clinically relevant setting, RNA-seq was performed on RA synovial fluid and peripheral blood. We identified enhanced expression of a number of glycolytic genes in synovial CD1c+ DC compared to CD1c+ DC in circulation. Collectively, our data suggest that the synovial microenvironment in RA contributes to DC maturation and metabolic reprogramming.

The Role of Autophagy and Mitophagy in Bone Metabolic Disorders

Bone metabolic disorders include osteolysis, osteoporosis, osteoarthritis and rheumatoid arthritis. Osteoblasts and osteoclasts are two major types of cells in bone constituting homeostasis. The imbalance between bone formation by osteoblasts and bone resorption by osteoclasts has been shown to have a direct contribution to the onset of these diseases. Recent evidence indicates that autophagy and mitophagy, the selective autophagy of mitochondria, may play a vital role in regulating the proliferation, differentiation and function of osteoblasts and osteoclasts. Several signaling pathways, including PINK1/Parkin, SIRT1, MAPK8/FOXO3, Beclin-1/BECN1, p62/SQSTM1, and mTOR pathways, have been implied in the regulation of autophagy and mitophagy in these cells. Here we review the current progress about the regulation of autophagy and mitophagy in osteoblasts and osteoclasts in these bone metabolic disorders, as well as the molecular signaling activated or deactivated during this process. Together, we hope to draw attention to the role of autophagy and mitophagy in bone metabolic disorders, and their potential as a new target for the treatment of bone metabolic diseases and the requirements of further mechanism studies.

Functional analysis of synovial fluid from osteoarthritic knee and carpometacarpal joints unravels different molecular profiles

OBJECTIVE

In this work, we aimed to elucidate the molecular mechanisms driving primary OA. By studying the dynamics of protein expression in two different types of OA joints we searched for similarities and disparities to identify key molecular mechanisms driving OA.

METHODS

For this purpose, human SF samples were obtained from CMC-I OA and knee joint of OA patients. SF samples were analysed by label-free quantitative liquid chromatography mass spectrometry. Disease-relevant proteins identified in proteomics studies, such as clusterin, paraoxonase/arylesterase 1 (PON1) and transthyretin were validated by enzyme-linked immunosorbent assays, and on the mRNA level by droplet digital PCR. Functional studies were performed in vitro using primary chondrocytes.

RESULTS

Differential proteomic changes were observed in the concentration of 40 proteins including clusterin, PON1 and transthyretin. Immunoassay analyses of clusterin, PON1, transthyretin and other inflammatory cytokines confirmed significant differences in protein concentration in SF of CMC-I and knee OA patients, with primarily lower protein expression levels in CMC-I. Functional studies on chondrocytes unequivocally demonstrated that stimulation with SF obtained from knee OA, in contrast to CMC-I OA joint, caused a significant upregulation in pro-inflammatory response, cell death and hypertrophy.

CONCLUSION

This study demonstrates that differential expression of molecular players in SF from different OA joints evokes diverse effects on primary chondrocytes. The pathomolecular mechanisms of OA may significantly differ in various joints, a finding that brings a new dimension into the pathogenesis of primary OA.

MicroRNA-27b-3p inhibits apoptosis of chondrocyte in rheumatoid arthritis by targeting HIPK2

BACKGROUND

Understanding the mechanism of chondrocytes degeneration could provide a new potential therapeutic idea for rheumatoid arthritis (RA) treatment. MicroRNA-27b-3p (miR-27b-3p) has been shown to regulate a variety of cell behaviors in various cell types. However, the role of miR-27b-3p in RA remains unknown.

MATERIALS AND METHODS

Expression of miR-27b-3p and HIPK2 in cartilage tissues and chondrocytes was characterized using qRT-PCR and Western blot. MiR-27b-3p was overexpressed or suppressed in chondrocytes to observe the potential role of miR-27b-3p.

RESULTS

We found declined miR-27b-3p and elevated HIPK2 in RA tissues and cells using qRT-PCR. Dual-luciferase reporter assay validated HIPK2 is a direct target of miR-27b-3p, confirmed by Western blot results. Pearson correlation presented that there was a significantly negative correlation between miR-27b-3p and HIPK2 mRNA. Overexpression of miR-27b-3p significantly reduced the expression of pro-apoptotic protein c-caspase3 and increased the expression of anti-apoptotic Bcl-2; however, downregulation of miR-27b-3p has a significant effect of inducing apoptosis. Furthermore, overexpression of miR-27b-3p combined with recombinant HIPK2 protein showed the inhibitory effect of miR-27b-3p was abolished by HIPK2.

CONCLUSION

We found declined miR-27b-3p and elevated HIPK2 in RA tissues and cells. Further in vitro studies demonstrated that miR-27b might inhibit chondrocyte apoptosis and thus attenuate RA development by directly inhibiting HIPK2 expression.

A photothermal-triggered nitric oxide nanogenerator combined with siRNA for precise therapy of osteoarthritis by suppressing macrophage inflammation

Although nitric oxide (NO) can be used to treat osteoarthritis (OA) by inhibiting inflammation, a method for the accurately controlled release of NO in inflammatory cells is still elusive. Herein, photothermal-triggered NO nanogenerators NO-Hb@siRNA@PLGA-PEG (NHsPP) were constructed by assembling photothermal-agents and NO molecules within nanoparticles. In the NHsPP nanoparticles the hemoglobin (Hb) nanoparticles can act as a NO carrier which can absorb near-infrared light at 650 nm (0.5 W cm-2) and convert it into heat to trigger the release of NO. Moreover, after loading Notch1-siRNA, precise treatment can be achieved. Furthermore, using the synergistic effect of photothermal therapy, the NHsPP nanoparticles achieved simultaneous treatment with NO, siRNA and PTT. Through this combination therapy, the therapeutic effect of the NHsPP nanoparticles was significantly enhanced compared to the treatment groups using only NO, siRNA or PTT. This combination therapy inhibits the inflammatory response effectively by reducing the level of pro-inflammatory cytokines and the macrophage response. Subsequently, guided by dual-modal imaging, the NHsPP nanoparticles can not only accumulate effectively in OA mice, but can also reduce the inflammatory response and efficiently prevent cartilage erosion, without causing toxic side effects in the major organs. Therefore, this novel photothermal nanoparticle-based NO-releasing system is expected to be a potential alternative for clinical inflammatory disease therapy and may provide image guidance when combined with other nanotherapy systems.

Terpenes as possible drugs for the mitigation of arthritic symptoms - A systematic review

BACKGROUND

Arthritis is a syndrome associated with exacerbated inflammation, joint destruction and chronic pain and disability. Chronic treatment of arthritis is associated with several side effects and high abandonment. Therefore, there has been an ongoing search for alternative treatments to overcome these problems.

PURPOSE

Natural products, which are already widely used for their biological, cosmetic and pharmacotechnic properties, are a possible source for new drugs. Terpenes, a large class of organic compounds produced mainly by plants and trees, are a promising natural product and have already been shown to be effective in treating chronic pain, particularly of an inflammatory origin.

STUDY DESIGN AND METHODS

This review identifies the main terpenes with anti-arthritic activity reported in the last 10 years. A survey was conducted between December 2017 and June 2018 in the PUBMED, SCOPUS and Science Direct databases using combinations of the descriptors terpenes, arthritis and inflammation.

RESULTS

The results showed that terpenes have promising biological effects in relation to the treatment of arthritis, with the 24 terpenes identified in our survey being effective in the modulation of inflammatory mediators important to the physiopathology of arthritis, such as IL-6, IL-17, TNF-α, NFκB, and COX-2, among others. It is important to note that most of the studies used animal models, which limits, at least in part, the direct translation to humans of the experimental evidence produced by the studies.

CONCLUSION

Together, our finds suggest that terpenes can modulate the immuno-regulatory and destructive tissue events that underlie the clinical presentation and the progression of arthritis and are worthy of further clinical investigation.

RETRACTED: Effects of Artesunate on chondrocyte proliferation, apoptosis and autophagy through the PI3K/AKT/mTOR signaling pathway in rat models with rheumatoid arthritis

This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy). This article has been retracted at the request of the Editor-in-Chief. Concern was raised about the reliability of the Western blot results in Figure 5D and 5F, which appear to have a similar phenotype as contained within another publication, as detailed here: https://pubpeer.com/publications/CD4DF7B6DCA28182EC6809846F3653; and here: https://docs.google.com/spreadsheets/d/1r0MyIYpagBc58BRF9c3luWNlCX8VUvUuPyYYXzxWvgY/edit#gid=262337249. Concerns were also raised about the provenance of the flow cytometry data in Figure 7A. In addition, suspected duplications were detected in Western blots contained within Figure 5E and 5F. The journal requested the corresponding author comment on these concerns and provide raw data. The corresponding author communicated that the raw data was not available and some of the results were not repeatable and therefore not solid enough to support the conclusions. The authors requested retraction of this article. The Editor-in-Chief assessed this case and decided to retract the article.

Serglycin is involved in inflammatory response in articular mouse chondrocytes

Serglycin is expressed by a variety of cell types and mediates different functions in both normal and pathological conditions by interacting with different biological molecules, such as the CD44 receptor. Many studies suggest that serglycin has a crucial role in inflammatory response, but there are limited data on the functions of this proteoglycan in chondrocytes. In this study we investigated the effect of serglycin knockdown induced by a specific serglycin small interfering RNA (SRGN siRNA) in normal mouse chondrocytes stimulated with lipopolysaccharide (LPS). LPS administration in normal chondrocytes increased the expression of serglycin mRNA and related protein and the production of the pro-inflammatory mediators TNF-alpha, IL-1beta, IL-6, iNOS and MMP-9, through NF-kB activation. In addition, a marked increased expression of CD44 after LPS stimulation was observed. Notably, the CD44 expression and the inflammatory response were significantly reduced by SRGN siRNA treatment in LPS treated chondrocytes. Similar results were obtained in normal mouse chondrocytes exposed to LPS, using a specific blocking antibody against CD44. These results indicate that serglycin produced in LPS-induced inflammation in normal mouse chondrocytes is able to modulate inflammation by interacting with CD44 receptor, suggesting a possible key role in the cartilage inflammation.

Cartilage Metabolism is Modulated by Synovial Fluid Through Metalloproteinase Activity

Synovial fluid (SF) contains various cytokines that regulate chondrocyte metabolism and is dynamically associated with joint disease. The objective of this study was to investigate the effects of diluted normal SF on catabolic metabolism of articular cartilage under inflammatory conditions. For this purpose, SF was isolated from healthy bovine joints, diluted, and added to cartilage explant cultures stimulated with interleukin-1 (IL-1) for 12 days. The kinetic release of sulfated glycosaminoglycan (sGAG) and collagen, as well as nitric oxide and gelatinase matrix metalloproteinases were analyzed in the supernatant. Chondrocyte survival and matrix integrity in the explants were evaluated with Live/Dead and histological staining. Diluted synovial fluid treatment suppressed sGAG and collagen release, downregulated the production of nitric oxide and matrix metalloproteinases, reduced IL-1-induced chondrocyte death, and rescued matrix depletion. Our results demonstrate that normal SF can counteract inflammation-driven cartilage catabolism. This study reports on the protective function of healthy SF and the therapeutic potential of recapitulation of SF for cartilage repair.

Screening of differentially expressed proteins in psoriasis vulgaris by two-dimensional gel electrophoresis and mass spectrometry

The aim of the present study was to elucidate differentially expressed proteins in lesional tissues of psoriasis vulgaris (PV) and normal tissues. Lesional skin tissues were collected from PV patients, along with normal skin tissues from healthy individuals. The protein content of the samples was extracted and then separated by two-dimensional gel electrophoresis (2-DGE). Any proteins that were differentially expressed in the lesional skin of PV patients compared with the healthy controls were analyzed by mass spectrometry and bioinformatics. In the stratum corneum and dermis of PV patients, the total number of proteins identified by 2-DGE was 1,969±21 and 1,928±49, respectively. Of these, 30 proteins were differentially expressed in the PV patients, of which 14 were identified as: Type 1 keratin cytoskeleton proteins (including K1C10, K1C14, K1C15 and K1C16); the type 2 keratin cytoskeleton protein, K2C1; actin-associated proteins (including ARP3, ACTA and ACTBM); prohibitin; heat shock proteins (HSPB1 and CH60); centrosome protein, CP135; and membrane associated proteins (including ANXA4 and ANXA5). The differential expression of protein between PV lesions and normal tissue can be considered as pathological biomarker. Elucidating the abnormal regulation of these proteins can provide mechanism of the development of PV and may contribute to significant approaches for PV treatments.

Distraction arthroplasty with arthroscopic microfracture in a patient with rheumatoid arthritis of the ankle joint

We treated a 39-year-old female who had experienced destruction of her ankle joint owing to rheumatoid arthritis. This relatively young patient wished to avoid ankle fusion and joint replacement. Therefore, distraction arthroplasty with arthroscopic microfracture was performed to improve her symptoms and preserve motion. A microfracture procedure specifically for cartilage defects of the tibial plafond and talar dome was performed with the arthroscope, after which a hinged external fixator was applied to distract the ankle joint. The ankle joint space was enlarged by the external device and joint movement allowed. After 3 months, removal of the external device and repeat arthroscopy revealed newly formed fibrocartilage on the surfaces of both the tibia and the talus. At 2 years after the surgery, a radiograph showed that the joint space enlargement of the ankle had been maintained. The American Orthopaedic Foot and Ankle Society score improved from 37 points preoperatively to 82 points at 2 years postoperatively. Our findings suggest that good clinical results can be achieved with distraction arthroplasty and arthroscopic microfracture in a relatively young patient with rheumatoid arthritis.

Icariside II inhibits cell proliferation and induces cell cycle arrest through the ROS-p38-p53 signaling pathway in A375 human melanoma cells

Icariside II (IS) is a metabolite of icariin, which is derived from Herba Epimedii. In the present study, the antiproliferative effects of IS on A375 human melanoma cells were examined in vitro and a possible mechanism through the ROS-p38-p53 pathway is discussed. A cell WST-8 assay revealed that treatment with IS markedly reduced cell viability from 77 to 21% (25 and 100 µM, respectively), and cell counting demonstrated that IS treatment reduced cell proliferation. IS treatment also induced cell cycle arrest of A375 cells at the G0/G1 and G2/M transitions and inhibited the expression of cell-cycle related proteins, including cyclin E, cyclin-dependent kinase 2 (CDK2), cyclin B1 and phosphorylated cyclin-dependent kinase 1 (P-CDK1). In this study, it was determined that IS inhibits cell proliferation and induces cell cycle arrest through the generation of reactive oxygen species and activation of p38 and p53. These findings were further supported by the evidence that pretreatment with N-acetyl-L-cysteine, SB203580 or pifithrin-α significantly blocked IS-induced reduction of cell viability, increase of cell death and cell cycle arrest. In conclusion, IS inhibits cell proliferation and induces cell cycle arrest. Crucially, it was confirmed that these effects were mediated at least in part by activating the ROS-p38-p53 pathway.

The role of total and cartilage-specific estrogen receptor alpha expression for the ameliorating effect of estrogen treatment on arthritis

INTRODUCTION

Estrogen (E2) delays onset and decreases severity of experimental arthritis. The aim of this study was to investigate the importance of total estrogen receptor alpha (ERα) expression and cartilage-specific ERα expression in genetically modified mice for the ameliorating effect of estrogen treatment in experimental arthritis.

METHODS

Mice with total (total ERα-/-) or cartilage-specific (Col2α1-ERα-/-) inactivation of ERα and wild-type (WT) littermates were ovariectomized, treated with E2 or placebo, and induced with antigen-induced arthritis (AIA). At termination, knees were collected for histology, synovial and splenic cells were investigated by using flow cytometry, and splenic cells were subjected to a T-cell proliferation assay.

RESULTS

E2 decreased synovitis and joint destruction in WT mice. Amelioration of arthritis was associated with decreased frequencies of inflammatory cells in synovial tissue and decreased splenic T-cell proliferation. E2 did not affect synovitis or joint destruction in total ERα-/- mice. In Col2α1-ERα-/- mice, E2 protected against joint destruction to a similar extent as in WT mice. In contrast, E2 did not significantly ameliorate synovitis in Col2α1-ERα-/- mice.

CONCLUSIONS

Treatment with E2 ameliorates both synovitis and joint destruction in ovariectomized mice with AIA via ERα. This decreased severity in arthritis is associated with decreased synovial inflammatory cell frequencies and reduced splenic T-cell proliferation. ERα expression in cartilage is not required for estrogenic amelioration of joint destruction. However, our data indicate that ERα expression in cartilage is involved in estrogenic effects on synovitis, suggesting different mechanisms for the amelioration of joint destruction and synovitis by E2.

Anti-inflammatory strategies in cartilage repair

Cartilage defects are normally concomitant with posttraumatic inflammation and pose a major challenge in cartilage repair. Due to the avascular nature of cartilage and its inability to surmount an inflammatory response, the cartilage is easily attacked by proinflammatory factors and oxidative stress; if left untreated, osteoarthritis may develop. Suppression of inflammation has always been a crux for cartilage repair. Pharmacological drugs have been successfully applied in cartilage repair; however, they cannot optimally work alone. This review article will summarize current pharmacological drugs and their application in cartilage repair. The development of extracellular matrix-based scaffolds and preconditioned tissue-specific stem cells will be emphasized because both of these tissue engineering components could contribute to an enhanced ability not only for cartilage regeneration but also for anti-inflammation. These strategies could be combined to boost cartilage repair under inflammatory conditions.

Cytokine levels (IL-4, IL-6, IL-8 and TGFβ) as potential biomarkers of systemic inflammatory response in trauma patients

PURPOSE

Much research is now being conducted in order to understand the role of cytokines in the development of the inflammatory response following trauma. The purpose of this study was to evaluate whether serum levels of certain cytokines, measured immediately after initial injury, can be used as potential biomarkers for predicting the development and the degree of severity of the systemic inflammatory response (SIRS) in patients with moderate and severe trauma.

METHODS

We conducted a prospective study with 71 individuals of whom 13 (18.3 %) were healthy controls and 58 (81.7 %) were traumatized orthopaedic patients who were categorized into two groups: 31 (43.6 %) with moderate injuries and 27 (38.1 %) patients with severe orthopaedic trauma. Thirty cc of heparinized blood were drawn from each individual within a few hours after the injury. Serum levels of pro-inflammatory, regulatory and anti-inflammatory cytokines were measured in each individual participant.

RESULTS

High levels of pro-inflammatory cytokines IL-1β,-6,-8,-12, tumour necrosis factor alpha and interferon gamma were found in all injured patients compared to healthy controls. Only IL-6 and IL-8 were significantly higher in the injured patients. Levels of the regulatory cytokines, transformed growth factor beta (TGF-β) and IL-10 were higher in the injured patients, but significant only for TGF-β. Levels of IL-4 were significantly lower in the injured groups as compared to the controls.

CONCLUSIONS

Secretion of large amounts of pro-inflammatory cytokines and decreased level of anti-inflammatory cytokines during the acute phase of trauma may lead to the development of systemic inflammatory response syndrome (SIRS) in unstable polytraumatized patients. SIRS may result in life threatening conditions as acute respiratory distress syndrome (ARDS) and multiple organ failure (MOF). High levels of IL-6, IL-8, TGFβ and low levels of IL-4 were found to be reliable markers for the existence of immune reactivity in trauma patients. More research is needed to study pattern of cytokine levels along the acute period of injury, after surgical interventions and during recovery.

Pronounced biomaterial dependency in cartilage regeneration using nonexpanded compared with expanded chondrocytes

Aim: We aimed to investigate freshly isolated compared with culture-expanded chondrocytes with respect to early regenerative response, cytokine production and cartilage formation in response to four commonly used biomaterials. Materials & methods: Chondrocytes were both directly and after expansion to passage 2, incorporated into four biomaterials: Polyactive™, Beriplast®, HyStem® and a type II collagen gel. Early cartilage matrix gene expression, cytokine production and glycosaminoglycan (GAG) and DNA content in response to these biomaterials were evaluated. Results: HyStem induced more GAG production, compared with all other biomaterials (p ≤ 0.001). Nonexpanded cells did not always produce more GAGs than expanded chondrocytes, as this was biomaterial-dependent. Cytokine production and early gene expression were not predictive for final regeneration. Conclusion: For chondrocyte-based cartilage treatments, the biomaterial best supporting cartilage matrix production will depend on the chondrocyte differentiation state and cannot be predicted from early gene expression or cytokine profile.

Prolactin promotes cartilage survival and attenuates inflammation in inflammatory arthritis

Chondrocytes are the only cells in cartilage, and their death by apoptosis contributes to cartilage loss in inflammatory joint diseases, such as rheumatoid arthritis (RA). A putative therapeutic intervention for RA is the inhibition of apoptosis-mediated cartilage degradation. The hormone prolactin (PRL) frequently increases in the circulation of patients with RA, but the role of hyperprolactinemia in disease activity is unclear. Here, we demonstrate that PRL inhibits the apoptosis of cultured chondrocytes in response to a mixture of proinflammatory cytokines (TNF-α, IL-1β, and IFN-γ) by preventing the induction of p53 and decreasing the BAX/BCL-2 ratio through a NO-independent, JAK2/STAT3-dependent pathway. Local treatment with PRL or increasing PRL circulating levels also prevented chondrocyte apoptosis evoked by injecting cytokines into the knee joints of rats, whereas the proapoptotic effect of cytokines was enhanced in PRL receptor-null (Prlr(-/-)) mice. Moreover, eliciting hyperprolactinemia in rats before or after inducing the adjuvant model of inflammatory arthritis reduced chondrocyte apoptosis, proinflammatory cytokine expression, pannus formation, bone erosion, joint swelling, and pain. These results reveal the protective effect of PRL against inflammation-induced chondrocyte apoptosis and the therapeutic potential of hyperprolactinemia to reduce permanent joint damage and inflammation in RA.

Competitive stem cell recruitment by multiple cytotactic cues

A multitude of cytotactic cues direct cell migration in development, cancer metastasis and wound healing. However, our understanding of cell motility remains fragmented partially because current migration devices only allow the study of independent factors. We developed a cell motility assay that allows competitive recruitment of a given cell population simultaneously by gradients of multiple cytotactic cues, observable under real-time imaging. Well-defined uniform gradients of cytotactic cues can be independently generated and sustained in each channel. As a case study, bone marrow mesenchymal stem/stromal cells (MSCs) were exposed to 15 cytokines that are commonly present in arthritis. Cytokines that induced robust recruitment of MSCs in multiple groups were selected to 'compete' in a final round to yield the most chemotactic factor(s) based on cell migration numbers, distances, migration indices and motility over time. The potency of a given cytokine in competition frequently differed from its individual action, substantiating the need to test multiple cytokines concurrently due to synergistic or antagonistic effects. This new device has the rare capacity to screen molecules that induce cell migration in cancer therapy, drug development and tissue regeneration.

Osteoarthritis synovial fluid activates pro-inflammatory cytokines in primary human chondrocytes

PURPOSE

Two of the most common joint diseases are rheumatoid arthritis (RA) and osteoarthritis (OA). Cartilage degradation and erosions are important pathogenetic mechanisms in both joint diseases and have presently gained increasing interest. The aim of the present study was to investigate the effects of the synovial fluid environment of OA patients in comparison with synovial fluids of RA patients on human chondrocytes in vitro.

METHODS

Primary human chondrocytes were incubated in synovial fluids gained from patients with OA or RA. The detection of vital cell numbers was determined by histology and by using the Casy Cell Counter System. Cytokine and chemokine secretion was determined by a multiplex suspension array.

RESULTS

Microscopic analysis showed altered cell morphology and cell shrinkage following incubation with synovial fluid of RA patients. Detection of vital cells showed a highly significant decrease of vital chondrocyte when treated with RA synovial fluids in comparison with OA synovial fluids. An active secretion of cytokines such as vascular endothelial growth factor (VEGF) of chondrocytes treated with OA synovial fluids was observed.

CONCLUSIONS

Significantly increased levels of various cytokines in synovial fluids of RA, and surprisingly of OA, patients were shown. Activation of pro-inflammatory cytokines of human chondrocytes by synovial fluids of OA patient supports a pro-inflammatory process in the pathogenesis of OA.