CAR Protects Females from Diet-Induced Steatosis and Associated Metabolic Disorders

Non-Alcoholic Fatty Liver Disease (NAFLD) is the most common cause of chronic liver disease worldwide, affecting 70-90% of obese individuals. In humans, a lower NAFLD incidence is reported in pre-menopausal women, although the mechanisms affording this protection remain under-investigated. Here, we tested the hypothesis that the constitutive androstane nuclear receptor (CAR) plays a role in the pathogenesis of experimental NAFLD. Male and female wild-type (WT) and CAR knock-out (CAR-/-) mice were subjected to a high-fat diet (HFD) for 16 weeks. We examined the metabolic phenotype of mice through body weight follow-up, glucose tolerance tests, analysis of plasmatic metabolic markers, hepatic lipid accumulation, and hepatic transcriptome. Finally, we examined the potential impact of HFD and CAR deletion on specific brain regions, focusing on glial cells. HFD-induced weight gain and hepatic steatosis are more pronounced in WT males than females. CAR-/- females present a NASH-like hepatic transcriptomic signature suggesting a potential NAFLD to NASH transition. Transcriptomic correlation analysis highlighted a possible cross-talk between CAR and ERα receptors. The peripheral effects of CAR deletion in female mice were associated with astrogliosis in the hypothalamus. These findings prove that nuclear receptor CAR may be a potential mechanism entry-point and a therapeutic target for treating NAFLD/NASH.

Steatosis and Metabolic Disorders Associated with Synergistic Activation of the CAR/RXR Heterodimer by Pesticides

The nuclear receptor, constitutive androstane receptor (CAR), which forms a heterodimer with the retinoid X receptor (RXR), was initially reported as a transcription factor that regulates hepatic genes involved in detoxication and energy metabolism. Different studies have shown that CAR activation results in metabolic disorders, including non-alcoholic fatty liver disease, by activating lipogenesis in the liver. Our objective was to determine whether synergistic activations of the CAR/RXR heterodimer could occur in vivo as described in vitro by other authors, and to assess the metabolic consequences. For this purpose, six pesticides, ligands of CAR, were selected, and Tri-butyl-tin (TBT) was used as an RXR agonist. In mice, CAR's synergic activation was induced by dieldrin associated with TBT, and combined effects were induced by propiconazole, bifenox, boscalid, and bupirimate. Moreover, a steatosis, characterized by increased triglycerides, was observed when TBT was combined with dieldrin, propiconazole, bifenox, boscalid, and bupirimate. Metabolic disruption appeared in the form of increased cholesterol and lowered free fatty acid plasma levels. An in-depth analysis revealed increased expression of genes involved in lipid synthesis and lipid import. These results contribute to the growing understanding of how environmental contaminants can influence nuclear receptor activity and associated health risks.

Effect of an oral preparation containing hyaluronic acid, chondroitin sulfate, hydrolyzed collagen type II and hydrolyzed keratin on synovial fluid features and clinical indices in knee osteoarthritis. A pilot study

The aim of this study was to evaluate the effect of an oral preparation containing a naturally occurring matrix of hydrolyzed collagen type II, chondroitin sulfate (CS), and hyaluronic acid (HA), and bioactive oligopeptides of natural hydrolyzed keratin (K) in patients affected by knee OA through the evaluation of synovial fluid (SF) and clinical changes before and after treatment. Thirty patients with knee OA and swollen joint were included in the study and submitted to arthrocentesis. Patients were randomized in two groups: 1) the treatment group (N.15) took a dietary supplement containing 120 mg HA, 240 mg CS and 300 mg K once a day for 4 weeks; 2) the control group (N.15) was only submitted to arthrocentesis. Patient symptoms were evaluated at the beginning and at the end of the study by the WOMAC self-assessment questionnaire, the Lequesne algofunctional index, and the VAS forms. SF changes were evaluated by measuring local inflammatory indices, cytokines IL-1β, IL-8, IL-6, IL-10 and GM-CSF. The group of patients treated with the oral supplement showed an improvement in the clinical indices WOMAC (p<0.01), Lequesne (p=0.014) and VAS pain (p<0.01). On the contrary, no significant changes were found in the control group. The SF collected from the treated group showed a reduction of IL-8 (p=0.015), IL-6 and IL-10 levels, while no changes in cytokines were observed in the control group. This pilot study suggests that an oral administration of a preparation containing a combination of HA, CS and K can improve some clinical parameters and affect cytokine concentrations in SF in patients with knee OA.

Constitutive Androstane Receptor: A Peripheral and a Neurovascular Stress or Environmental Sensor

Xenobiotic nuclear receptors (NR) are intracellular players involved in an increasing number of physiological processes. Examined and characterized in peripheral organs where they govern metabolic, transport and detoxification mechanisms, accumulating data suggest a functional expression of specific NR at the neurovascular unit (NVU). Here, we focus on the Constitutive Androstane Receptor (CAR), expressed in detoxifying organs such as the liver, intestines and kidneys. By direct and indirect activation, CAR is implicated in hepatic detoxification of xenobiotics, environmental contaminants, and endogenous molecules (bilirubin, bile acids). Importantly, CAR participates in physiological stress adaptation responses, hormonal and energy homeostasis due to glucose and lipid sensing. We next analyze the emerging evidence supporting a role of CAR in NVU cells including the blood-brain barrier (BBB), a key vascular interface regulating communications between the brain and the periphery. We address the emerging concept of how CAR may regulate specific P450 cytochromes at the NVU and the associated relevance to brain diseases. A clear understanding of how CAR engages during pathological conditions could enable new mechanistic, and perhaps pharmacological, entry-points within a peripheral-brain axis.

Life-long Dietary Pesticide Cocktail Induces Astrogliosis Along with Behavioral Adaptations and Activates p450 Metabolic Pathways

Exposure to environmental contaminants is a public health concern. However, pre-clinical studies that examine the impact of pesticides at low-dose and the long-term consequences are uncommon. Here, C57BL6/j male and female mice were daily fed from weaning and up to 12 months, corresponding to early-childhood into middle-age in humans, using chow pellets containing a cocktail of pesticides at tolerable daily intake levels. We found that 12 months of dietary exposure to pesticides was associated with a moderate perenchymal or perivascular astrogliosis in specific hippocampal sub-regions. The expression of platelet-derived growth factor receptor beta was modified at the perivascular level. Examination of Iba1⁺ microglial cells did not reveal sizeable changes. Concomitantly to astrogliosis, spontaneous spatial memory and sociability were modified in males at 12 months of dietary exposure to pesticides. Telemetry electrocorticograhic explorations ruled out the presence of epileptiform activity or theta-gamma wave modifications in these conditions. Long-term pesticides impacted the periphery where the hepatic P450 metabolic cytochromes Cyp4a14 and Cyp4a10 were significantly upregulated in male and female mice during the 12 months of exposure. The expression of β-oxidation genes, such as Acox1, Cpt1a and Eci, was also significantly increased in male and female mice in response to pesticides. Collectively, our results indicate that a life-long exposure to a pesticide cocktail elicits sex-dependent, spatio-temporally restricted brain modifications and significant activation of P450 pathways in the periphery. These brain-peripheral adjustments are discussed as time or age-dependent vulnerability elements.

AB0060 STING AND PROINFLAMMATORY CYTOKINES IN SYNOVIAL FLUID OF PATIENTS WITH DIFFERENT ARTHRITIDES

Background:

STING (stimulator of interferon genes) is a cytosolic protein that is found in endoplasmic reticulum (ER) membrane, mitochondria and mitochondria-associated membranes. Although it is well established that STING plays an important role in innate immune responses, its potential involvement in rheumatic disease processes remains to be clarified (1).

Objectives:

The aims of this study were to evaluate the levels of STING and its relationship with local inflammation in the synovial fluid (SF) of patients with psoriatic arthritis (PsA), rheumatoid arthritis (RA), gout, calcium pyrophosphate (CPP) crystal-induced arthritis (CPP-IA), osteoarthritis (OA) and OA with CPP crystals (OA+CPP).

Methods:

SF was collected from the knees of 60 untreated patients: 10 with PsA, 10 with RA, 10 with gout, 10 with CPP-IA, 10 with OA and 10 with OA+CPP. SF was examined under optical light microscopy. White cell count (WBC) and the polymorphonuclear cell (PMN) percentage were determined in SF according to standard procedures. SF IL-8, IL-6, IL-1β and extra- and intra-cellular STING levels were assayed by ELISA.

Results:

The levels of WBC were higher in SFs from gouty patients (27.7±20.56 103/mm3), while OA and OA+CPP patients showed the lowest WBC count (0.34±0.3 103/mm3, 0.3±0.28 103/mm3). SFs from inflammatory arthritis contained elevated percentages of PMN (gout: 85.5±10.86%, CPP-IA: 84±11.31%, RA: 80.33±8.14%, PsA: 42.6±35.97%). Extracellular STING was determined in OA (440±413.31 pg/ml), OA+CPP (225±205.06 pg/ml) and CPP-IA (475±7.07 pg/ml) SF, while was not detectable in RA, PsA and gout. Intracellular STING levels were similar and the highest in SFs from gout (96.4±35.44 pg/ml) and RA (90.64±23.13 pg/ml), while remained under detection limit only in SFs from PsA. SF concentration of IL-6 was lower in OA (354.87±377.56 pg/ml) and OA+CPP (389.56±104.14 pg/ml) as compared with inflammatory arthritides (PsA: 3807.14±489.86 pg/ml; RA: 17354±2334.87 pg/ml; gout: 19359±84.85 pg/ml; CPP-IA: 20389.56±104.14 pg/ml). The patients with gout and RA had the highest levels of IL-8 (2159.54±347.09 pg/ml; 2039.6±97.74 pg/ml) and IL-1β (35.93±20.46 pg/ml; 44.36±23.16 pg/ml), while OA showed the lowest concentrations (IL-8: 23.21±11.32 pg/ml; IL-1β: 0.47±0.13 pg/ml). In the total group of patients, we found a negative correlation between extracellular STING and IL-8 (r=-0.53; p=0.004) and IL-1β (r=-0.47; p=0.012). There was a positive correlation between intracellular STING and IL-8 (r=0.54; p=0.017), IL-1β (r=0.77; p<0.001) and IL-6 (r=0.69 p=0.009).

Conclusion:

This study is the first to define the presence of STING in SF of different arthritides. The high levels of extracellular STING in OA, OA+CPP and CPP-IA SFs may be due to the activation of factors that reduce its interaction with the ER. The effect of downregulating factors in PsA might explain the low concentration of intracellular STING in these patients.

References:

[1]Barber GN. STING: infection, inflammation and cancer. Nat Rev Immunol 2015;15:760-70.

Disclosure of Interests:

Anna Scanu: None declared, Roberto Luisetto: None declared, Francesca Oliviero: None declared, Paola Galozzi: None declared, Augusta Ortolan: None declared, Mariagrazia Lorenzin: None declared, Mara Felicetti: None declared, Andrea Doria Consultant of: GSK, Pfizer, Abbvie, Novartis, Ely Lilly, Speakers bureau: UCB pharma, GSK, Pfizer, Janssen, Abbvie, Novartis, Ely Lilly, BMS, Roberta Ramonda Speakers bureau: Novartis, Celgene, Janssen, Pfizer, Abbvie, Lilly

OP0174 POLYDATIN PREVENTS CALCIUM PYROPHOSPHATE CRYSTAL-INDUCED ARTHRITIS IN MICE

Background:

Acute calcium pyrophosphate (CPP) crystal-induced inflammation is characterized by the massive release of cytokines and pro-inflammatory mediators and, from a clinical point of view, pain and limited joint function. Contrary to the precipitation of urate crystals that can be prevented through the use of hypouricemic drugs, there is no pharmacological therapy that can prevent the formation of pyrophosphate crystals.

Polydatin (PD),a natural precursor of resveratrol, is a stilbenoid mainly contained in grape juice and bark of Polygonum Cuspidate. Its antioxidant, anti-inflammatory and immunomodulating properties have been demonstrated in several experimental models. We have recently shown that this compound is able to prevent the inflammatory response to pathogenic crystals in vitro (1).

Objectives:

The aim of this study was to assess the anti-inflammatory preventing effect of polydatin in the mouse model of acute crystal-induced arthritis.

Methods:

A suspension of sterile CPP crystals (0.3 mg/20 μL PBS) have been injected intra-articularly (i.a.) into one ankle joint of Balb/c mice under isoflurane anesthesia. Animals were randomized in 5 groups: 1- CPP injection, 2- CPP + PD, 3- CPP + colchicine (control drug), 4- CPP + vehicle (control. N 1), 5- PBS injection (control N. 2). Polydatin and colchicine were administered by gavage (respectively 40 mg/kg and 1mg/kg in 200 μL PBS/EtOH/glucose) at 24, 15 and 1 h before and 1, 6 and 24 h after (prophylactic model) or 1, 6 and 24 h after (therapeutic model) i.a. injection of CPP crystals.

Ankle swelling was measured at different time points using a precision caliper. After 48h (peak of the acute phase) mice were euthanized and blood and ankle joints were collected for inflammatory cytokine (IL-1ß and KC) determination and histological analysis, respectively.

Results:

The mean change in ankle swelling after i.a injection was 0.595±0.434 mm. Prophylactic treatment with PD and colchicine significantly diminished ankle swelling to 0.175±0.115 mm and 0.137±0.100 mm, respectively (Kruskal Wallis p 0.0025; Dunn’s post test p < 0.01 CPP vs PD+CPP). The therapeutic administration of PD did not have significant effects on delta swelling (0.468±0.372 mm - PD vs 0.243±0.152 mm - colchicine). In mice treated with CPP crystals, histological analysis revealed areas of edema and increased cell infiltrate in articular and periarticular tissues and the presence of reactive lymphnodes. Tissue necrosis around inflamed tissue has been observed. Treatment with PD importantly reduced cell infiltrate in the prophylactic but not in the therapeutic protocol.

Serum IL-1ß and KC levels, which increased significantly (p<0.05) after 48h from i.a injection, diminished in non significant manner after prophylactic and therapeutic treatment. The gene expression study revealed a reduction of IL-1ß and KC mRNA after PD and colchicine treatment in both groups.

Conclusion:

PD can effectively prevent acute inflammatory response to crystals in the mouse model of CPP arthritis. Oral PD prophylactic treatment showed a similar effect of colchicine in reducing ankle swelling and cell infiltrate. However, only colchicine showed to be effective in the therapeutic protocol.

These results raise the possibility that PD might have utility in the prevention of crystal-induced acute attacks in humans.

References:

[1]Oliviero F, et al. Polydatin and resveratrol inhibit the inflammatory process induced by urate and pyrophosphate crystals in thp-1 cells.Foods 2019 Nov 7;8(11). pii: E560.

Disclosure of Interests:

Francesca Oliviero: None declared, Francesca Galuppini: None declared, Anna Scanu: None declared, Paola Galozzi: None declared, Vanni Lazzarin: None declared, Paolo Sfriso: None declared, Gianpietro Ravagnan: None declared, Roberta Ramonda Speakers bureau: Novartis, Celgene, Janssen, Pfizer, Abbvie, Lilly, Paolo Spinella: None declared, LEONARDO PUNZI: None declared, Gianmaria Pennelli: None declared, Roberto Luisetto: None declared

Distinct tribological endotypes of pathological human synovial fluid reveal characteristic biomarkers and variation in efficacy of viscosupplementation at reducing local strains in articular cartilage

OBJECTIVE

Viscosupplementation has been used for decades to treat mild to moderate osteoarthritis, yet it is unknown if the lubricating function of different pathological synovial fluids (SF) vary, or if they respond differentially to viscosupplementation. The objectives of this study were to (i) evaluate the friction coefficients and induced shear strains in articular cartilage when lubricated with pathological SF, (ii) identify the effect of hyaluronic acid (HA) supplementation on friction coefficients and shear strains, and (iii) identify SF biomarkers that correlate with lubricating function.

METHOD

Human pathological SF was grouped by white blood cell count (inflammatory: >2000 cells/mm³, n = 6; non-inflammatory: <2000 cells/mm³, n = 6). Compositional analyses for lubricin and cytokines were performed. Friction coefficients and local tissue shear strain measurements were coupled using new, microscale rheological analyses by lubricating neonatal bovine cartilage explants with SF alone and in a 1:1 ratio with HA (Hymovis®).

RESULTS

Friction coefficients were not significantly different between the inflammatory and non-inflammatory pathologies (p = 0.09), and were poorly correlated with peak tissue strains at the cartilage articular surface (R² = 0.34). A subset of inflammatory SF samples induced higher tissue strains, and HA supplementation was most effective at lowering friction and tissue strains in this inflammatory subset. Across all pathologies there were clear relationships between polymorphonuclear neutrophil (PMN), IL-8, and lubricin concentrations with cartilage tissue strains.

CONCLUSION

These results suggest that pathological SF is characterized by distinct tribological endotypes where SF lubricating behaviors are differentially modified by viscosupplementation and are identifiable by biomarkers.

Author Correction: Dimorphic metabolic and endocrine disorders in mice lacking the constitutive androstane receptor

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Biomarkers, imaging and disease activity indices in patients with early axial spondyloarthritis: the Italian arm of the SpondyloArthritis-Caught-Early (SPACE) Study

The study aimed to evaluate biomarkers facilitating early diagnosis of axial spondyloarthritis (axSpA) and correlations between them and disease activity parameters and imaging indexes. Patients with low back pain (LBP) (≥3 months, ≤2 years, onset ≤45 years) participating in the Italian arm of the SpondyloArthritis-Caught-Early SPACE study underwent a physical examination, questionnaires, laboratory tests, X-rays and MRI of the spine and sacroiliac joints (SIJ). An expert rheumatologist formulated axSpA diagnosis in accordance with Assessment of SpondyloArthritis International Society (ASAS) criteria. Disease activity and physical functioning were assessed using imaging, clinical and serological indices. Spine and SIJ MRI and X-rays were scored independently by 2 readers using the SPARCC, mSASSS and NY-criteria. Patients were classified as: subjects with signs of radiographic sacroiliitis (r-axSpA), subjects with signs of sacroiliitis on SIJ-MRI but not on X-rays (nr-axSpA MRI SIJ+) or subjects with no signs of sacroiliitis on MRI/X-rays but with >2 SpA features and signs of bone oedema on MRI spine (nr-axSpA MRI SIJ-/undifferentiated SpA). Significant differences were found in the prevalence of radiographic sacroiliitis, active sacroiliitis on MRI and SPARCC SIJ scores. Biomarker levels were not significantly increased in any of the patient groups. The correlations between IL-17 and IL-23 and other indices were not significant; correlations were found between IL-22 and BASFI, BASG1, HAQ, VAS pain, between mSASSS and MMP3, and between the latter and hsCRP. Although not significantly higher in any of the three groups, IL-22, MMP3 and hsCRP values were correlated with some disease activity indexes and with mSASSS. Large observational studies are required to confirm these preliminary findings.

Spine and sacroiliac joints on magnetic resonance imaging in patients with early axial spondyloarthritis: prevalence of lesions and association with clinical and disease activity indices from the Italian group of the SPACE study

Our aim was to determine the prevalence of spine and sacroiliac joint (SIJ) lesions on magnetic resonance imaging (MRI) in patients with early axial spondyloarthritis (axSpA) and their correlation with disease activity indices. Sixty patients with low back pain (LBP) (≥3 months, ≤2 years, onset ≤45 years), attending the SpA-clinic of the Unità Operativa Complessa Reumatologia of Padova [SpondyloArthritis-Caught-Early (SPACE) study], were studied following a protocol including physical examination, questionnaires, laboratory tests, X-rays and spine and SIJ MRI. Positive spine and SIJ MRI and X-rays images were scored independently by 2 readers using the SPARCC method, modified Stoke ankylosing spondylitis spine score and New York criteria. The axial pain and localization of MRI-lesions were referred to 4 sites: cervical/thoracic/lumbar spine and SIJ. All patients were classified into three groups: patients with signs of radiographic sacroiliitis (r-axSpA), patients without signs of r-axSpA but with signs of sacroiliitis on MRI (nr-axSpA MRI SIJ+), patients without signs of sacroiliitis on MRI and X-rays (nr-axSpA MRI SIJ-). The median age at LBP onset was 29.05±8.38 years; 51.6% of patients showed bone marrow edema (BME) in spine-MRI and 56.7% of patients in SIJ-MRI. Signs of enthesitis were found in 55% of patients in the thoracic district. Of the 55% of patients with BME on spine-MRI, 15% presented presented a negative SIJMRI. There was a significant difference between these cohorts with regard to the prevalence of radiographic sacroiliitis, active sacroiliitis on MRI and SPARCC SIJ score. The site of pain correlated statistically with BME lesions in thoracic and buttock districts. Since positive spine-MRI images were observed in absence of sacroiliitis, we can hypothesize that this finding could have a diagnostic significance in axSpA suspected axSpA.

Pain and microcrystalline arthritis

Microcrystals are responsible for some of the most common and complex arthropathies which are often accompanied by intense, severe pain and inflammatory reactions. The main pathogens are crystals of monosodium urate (MSU), responsible for the gout, calcium pyrophosphate (CPP), which deposits also in various clinical forms of arthopathies, and basic calcium phosphate associated with osteoarthritis. In this context, the microcrystal arthritis is characterized by multiple, acute attacks followed by chronic pain, disability, impaired quality of life, and increased mortality. Given their chronic nature, they represent an ever more urgent public health problem. MSU and CPP crystals are also able to activate nociceptors. The pain in mycrocrystalline arthritis (MCA) is an expression of the inflammatory process. In the course of these diseases there is an abundant release of inflammatory molecules, including prostaglandins 2 and kinins. Interleukin-1 represents the most important cytokine released during the crystal-induced inflammatory process. Therefore, clinically, pain is the most important component of MCA, which lead to functional impairment and disability in a large proportion of the population. It is fundamental to diagnose these diseases as early as possible, and to this aim, to identify appropriate and specific targets for a timely therapeutic intervention.

Laboratory findings in psoriatic arthritis

Psoriatic arthritis (PsA) has been classically defined as an inflammatory arthritis associated with psoriasis. However, in comparison with other relevant inflammatory arthropathies, in which a definite diagnosis is frequently possible only by means of laboratory investigations, in PsA true laboratory diagnostic markers are lacking. Some markers are utilised more to differentiate other diseases than to characterise PsA. For example in polyarticular PsA, which may be in some cases indistinguishable from RA, the rheumatoid factor (RF) or the more specific and recently introduced antibodies to cyclic citrullinated peptides (anti-CCP), may be useful to better identify RA. However, RF was found in 5% to 13% of patients with PsA, and anti-CCP may be observed in almost similar percentage. The determination of ESR and/or CRP is frequently disappointing in PsA, since they are both elevated in only half of the patients with PsA. However, ESR and/or CRP are included in the most utilised response criteria for RA, such as ACR and DAS, and, in addition are also considered reliable in the assessment of PsA. Furthermore, elevated levels of ESR have been proposed as one of the best predictors of damage progression and, in addition, a low ESR seems protective, while an ESR >15 mm/h is one of the factors associated with an increased mortality in PsA. The synovial fluid (SF) effusion is much higher in PsA, in comparison with other arthropathies. When available, SF analysis may offer additive information useful for the diagnosis, such as the increased number of leukocytes, which underlines the inflammatory nature of the effusion even in a patient with normal serum levels of acute phase response. We found that elevated IL-1 levels in SF of patients with early disease (<6 months), may be predictive of an evolution in polyarticular form at follow-up. This observation is in keeping with the crucial role that inflammatory cytokines play in PsA, probably related to a genetic predisposition. The recent introduction in PsA of anti-TNF-alpha agents and the demonstration of their efficacy in the management of many clinical disease expressions including peripheral arthropathy, axial involvement, enthesopathy and skin manifestations, have stimulated the research also in the field of the possible laboratory markers.

Synovial colony-stimulating factor-1 mRNA expression in diffuse pigmented villonodular synovitis

OBJECTIVES

To delineate the molecular mechanisms underlying the process of the diffuse-type giant cell tumours, also called pigmented villonodular synovitis, a rare, aggressive condition of the synovium, the knee synovial tissue expression of colony-stimulating factor-1 gene, as detected by real-time polymerase chain reaction, was compared between patients affected with pigmented villonodular knee synovitis and knee meniscal tears, or persistent gonoarthitis.

METHODS

Multiple synovial biopsies of the knee were performed by arthroscopy in five consecutive patients affected by diffuse pigmented villonodular knee synovitis and in 12 patients affected by knee meniscal tears (n. 6) or persistent active gonarthritis (n. 6), recruited from the patients attending the Rheumatology Day Surgery Outpatient Clinic of the University of Padova Hospital. The ethics committee approved the study protocol and the participants signed consent statements after being informed about the content of the study. The diagnosis was made on the basis of a histological examination. The colony-stimulating factor-1 gene expression was assessed by reverse transcription followed by real-time polymerase chain reaction.

RESULTS

The detection by RT-PCR of synovial colony-stimulating factor-1 mRNA showed a wide spectrum of expression in the three groups of distinct knee joint disease affected patients, with significantly higher level of colony-stimulating factor-1 mRNA expression in synovial tissue of pigmented villonodular synovitis, in comparison to that of knee meniscal injuries and persistent gonoarthritis patients.

CONCLUSIONS

Our findings point out to an important role of colony-stimulating factor-1 in pigmented villonodular knee synovitis disease process and support the idea that colony-stimulating factor-1/colony-stimulating factor-1 receptor interaction may represent a potential therapeutic target of this disease.

[HDL inhibit cytokine production in a mouse model of urate crystal-induced inflammation]

OBJECTIVES

To evaluate whether high density lipoproteins (HDL) affect monosodium urate (MSU) crystal-induced inflammation in the murine air pouch model.

METHODS

MSU crystals were prepared by Denko's method and sterilized by heating at 180°C for 2 h before each experiment. Human HDL were isolated from peripheral blood of healthy volunteers. MSU crystals (2 mg in 1 ml of PBS) were injected into subcutaneous air pouches in mice in the presence or absence of HDL (0.1 mg). Negative control pouches received 1 ml of PBS. To recover pouch fluid, the pouches were washed with 2 ml of PBS after the animals were sacrificed. The leukocyte count in the lavage fluids was obtained using a hemocytometer and differential leukocyte count was determined by May-Grunwald-Giemsa staining. IL-6, KC, CCL2 and TNF-α levels were measured in exudates by ELISA.

RESULTS

MSU crystals increased the number of leukocytes and the neutrophil migration, as well as the concentrations of IL-6, KC and CCL2 in pouch fluids, while the TNF-α levels were not detectable. The treatment with HDL led to a reduction in all inflammatory parameters: the leukocyte count decreased by 73%; the neutrophil density decreased by 35%; the IL-6, KC and CCL2 concentration decreased by 4-, 6- and 5-fold respectively.

CONCLUSIONS

This study shows that HDL may limit the inflammatory process by inhibiting leukocyte recruitment and cytokine release. HDL are likely to represent a mechanism of control of crystal-induced inflammation.

New horizons in osteoarthritis

Osteoarthritis (OA), also known as degenerative joint disease, is the most frequent chronic musculoskeletal disease and the leading cause of disability in elderly persons. There are currently at least 27 million persons afflicted with OA in the United States, and the annual cost to society in medical care and wage loss is expected to reach nearly $100 billion dollars by 2020, with consequent increased spending on its diagnosis and treatment, side effect prevention, and loss of productivity. Despite this enormous burden, many aspects of OA are still unknown, with implications not only in terms of diagnosis and assessment but also with regard to therapy. Awareness of this state of affairs has attracted many researchers to this field, making OA one of the most actively studied sectors of rheumatology. Although some clinicians are unaware of recent advances, there is a large body of publications indicating that much has been achieved. Major progress has been made in formulating better definitions of risk factors, in particular in indicating the responsibility of biomechanical and genetic factors, and, with regard to pathogenesis, underlining the role of subchondral bone, cytokines and proteinases. Assessment of OA activity and its progression has been improved with the advent of biomarkers and new imaging procedures, in particular sonography and magnetic resonance imaging (MRI), but also of better clinical instruments, including more reliable patient questionnaires. Information from ongoing studies may improve the to some extent incomplete definition of OA phenotypes. Finally, promising new horizons have been opened up even with regard to the treatment of OA, which is still for the most part unsatisfactory except for surgical replacement therapy. Numerous new substances have been formulated and the findings of trials studying their effects are encouraging, although much has yet to be done.

Molecular pathways involved in synovial cell inflammation and tumoral proliferation in diffuse pigmented villonodular synovitis

Diffuse-type tenosynovial giant cell tumors, also known as pigmented villonodular synovitis, are unique mesenchymal lesions that arise from the synovial tissue of the joints. They are predominantly intraarticular, aggressive, infiltrative processes, characterized by both inflammatory or neoplastic properties and local destructive progression. The pattern of synovial gene and protein expressions in pigmented villonodular synovitis, similar to those in activated macrophages in rheumatoid arthritis, and the phenotype of multinucleated giant cells, characteristic of osteoclasts, suggest that there is a common autocrine mechanism in osteoclast differentiation in both diseases and indicate the potential utility of tumor necrosis factor (TNF)-alpha blockade. High synovial colony stimulating factor 1 (CSF1) messenger RNA (m RNA) expression in pigmented villonodular synovitis, unrelated to a chromosomal translocation involving CSF1 locus, may indicate that there is a synergic paracrine loop mediated by TNF-alpha and CSF1, as shown in both inflammatory and neoplastic conditions. The effects of a new therapeutic approach consisting in intraarticular TNF-alpha blockade were studied in four pigmented villonodular synovitis knees. Knee injections produced a rapid reduction in clinical and sonographic indexes and immunohistological alterations, confirmed by arthroscopic synovectomy. A delayed relapse in one of the four knees and unaltered synovial CSF1 expression were other important findings. In the light of these observations, CSF1/CSF1R interaction probably represents a more sensible therapeutic target than TNF-alpha blockade in the diffuse form of pigmented villonodular synovitis.