Endocan Knockdown Down-Regulates the Expression of Angiogenesis-Associated Genes in Il-1ß Activated Chondrocytes

Endocan is a small soluble proteoglycan (PG) known to be involved in inflammation and angiogenesis. Increased endocan expression was found in the synovia of arthritic patients and chondrocytes stimulated with IL-1ß. Considering these findings, we aimed to investigate the effects of endocan knockdown on the modulation of pro-angiogenic molecules expression in a model of IL-1ß-induced inflammation in human articular chondrocytes. Endocan, VEGF-A, MMP-9, MMP-13, and VEGFR-2 expression was measured in both normal and endocan knockdown chondrocytes stimulated with IL-1ß. VEGFR-2 and NF-kB activation were also measured. Results have shown that endocan, VEGF-A, VEGFR-2, MMP-9, and MMP-13 were significantly up-regulated during IL-1ß-induced inflammation; interestingly, the expression of such pro-angiogenic molecules and NF-kB activation were significantly reduced by endocan knockdown. These data support the hypothesis that endocan released by activated chondrocytes may be involved in the mechanisms that stimulate cell migration and invasion, as well as angiogenesis, in the pannus of arthritic joints.

Endocan Promotes Pro-Tumorigenic Signaling in Lung Cancer Cells: Modulation of Cell Proliferation, Migration and lncRNAs H19 and HULC Expression

Endocan is a circulating proteoglycan secreted by several cell lines and identified as a potential biomarker of inflammation and angiogenesis. Endocan-increased expression has been found in a broad spectrum of human tumors, including lung cancer, and is associated with a poor prognosis. To elucidate the possible mechanism, this study aimed to investigate the role of endocan in non-small-cell lung carcinoma (NSCLC) using an in vitro model of cultured cells. Endocan expression was knocked down by using a specific small interfering RNA. The effects of endocan knockdown have been evaluated on VEGF-A, VEGFR-2, HIF-1α, the long non-coding RNAs H19 and HULC expression, and AKT and ERK 1/2 degree of activation. Cell migration and proliferation have been studied as well. VEGF-A, VEGFR-2, HIF-1α, and the long non-coding RNAs H19 and HULC expression were significantly affected by endocan knockdown. These effects correlated with a reduction of cell migration and proliferation and of AKT and ERK 1/2 activation. Our findings suggest that endocan promotes a more aggressive cancer cell phenotype in NSCLC.

Corrigendum: Exploiting curcumin synergy with natural products using quantitative analysis of dose-effect relationships in an experimental in vitro model of osteoarthritis

[This corrects the article DOI: 10.3389/fphar.2019.01347.].

Drug-Induced Photosensitivity: Clinical Types of Phototoxicity and Photoallergy and Pathogenetic Mechanisms

Drug-induced photosensitivity (DIP) is a common cutaneous adverse drug reaction, resulting from the interaction of ultraviolet radiations, mostly ultraviolet A, with drugs. DIP includes phototoxicity and photoallergy. A phototoxic reaction is obtained when topical and systemic drugs or their metabolites absorb light inducing a direct cellular damage, while a photoallergic reaction takes place when the interaction between drugs and ultraviolet radiations causes an immune cutaneous response. Clinically, phototoxicity is immediate and appears as an exaggerated sunburn, whereas photoallergy is a delayed eczematous reaction. DIP may show several clinical subtypes. In this mini-review we report the pathogenetic mechanisms and causative drugs of DIP. We offer a detailed description of DIP clinical features in its classical and unusual subtypes, such as hyperpigmentation/dyschromia, pseudoporphyria, photo-onycolysis, eruptive teleangiectasia, pellagra-like reaction, lichenoid reaction, photodistributed erythema multiforme and subacute/chronic cutaneous lupus erythematosus. We described how physicians may early recognize and manage DIP, including diagnostic tests to rule out similar conditions. We made suggestions on how to improve sun exposure behaviors of patients at risk of DIP by means of an aware use of sunscreens, protective clothing and recent technologic tools. We highlighted the lack of sun safety programs addressed to patients at risk of DIP, who need a formal education about their condition.

miR9 inhibits 6-mer HA-induced cytokine production and apoptosis in human chondrocytes by reducing NF-kB activation

The present study aimed to investigate the expression of miR9 and its correlation with cytokines, proteolytic enzymes and apoptosis in an experimental model of 6-mer HA induced inflammation in human chondrocytes. Human articular chondrocytes, transfected with a miR-9 mimic and miR-9 inhibitor, were stimulated with 6-mer HA in presence/absence of a specific NF-kB inhibitor. 6-mer HA induced a significant increase of TLR-4, CD44, IL-8, IL-18, MMP-9, ADAMTS-5, BAX and BCL-2 mRNAs expression and the related proteins, as well as NF-kB activation, associated with a significant up regulation of miR-9. In chondrocytes transfected with the miR-9 mimic before 6-mer HA treatment we found a decrease of such inflammatory cytokines, metalloproteases and pro-apoptotic molecules, while we found them increased in chondrocytes transfected with the miR9 inhibitor before 6-mer HA stimulation. The activities of TLR-4 and CD44, up regulated by 6-mer HA, were not modified by miR9 mimic/inhibitor, while the NF-kB activation was significantly affected. We suggested that the up regulation of miR9, induced by 6-mer HA, could be a cellular attempt to limit cell damage during inflammation.

Expression and Change of miRs 145, 221 and 222 in Hypertensive Subjects Treated with Enalapril, Losartan or Olmesartan

miR profile could be associated to CV risk, and also to prognosis/outcome in response to therapeutic approach. We aimed to evaluate if anti-hypertensive drugs enalapril, losartan or olmesartan have effects on monocyte miR profile in essential hypertensives without target organ involvement. For this purpose, 82 hypertensives and 49 controls were included; we evaluated SBP/DBP, lipid profile, glucose, CRP, fibrinogen, arterial stiffness indices (PWV; AIx), and cIMT at baseline (T0) and after 24 weeks of treatment (T1). Subjects with LDL-C ≥ 160 mg/dL, TG ≥ 200 mg/dL, BMI ≥ 30, and other additional CV risk factors were excluded. Patients who were prescribed to receive once-a-day enalapril 20 mg, losartan 100 mg or olmesartan 20 mg were eligible for the study. At T1, we found a significant improvement of SBP (-18.5%), DBP (-18%), HDL-C and LDL-C (+3% and -5.42%), glucose (-2.15%), BMI (-3.23%), fibrinogen (-11%), CRP (-17.5%,), AIx (-49.1%) PWV (-32.2%), and monocyte miR expression (miR-221: -28.4%; miR-222: -36%; miR-145: +41.7%) with respect to baseline. miR profile was compared to control subjects at baseline and at T1. We found some little difference in the behaviour of the three treatments on some variables: olmesartan was the most effective in reducing fibrinogen, DBP, CRP, and AIx (-13.1%, -19.3%, -21.4%, and -56.8%, respectively). Enalapril was the drug more significantly increasing the expression of miR-145. In conclusion, enalapril, losartan and olmesartan are effective in improving mechanical and humoral factors associated to AS and atherogenesis. These drugs appear to be able to modify miRs 221/222 and miR-145 expression in drug-naïve hypertensives, making it closer to that of control subjects; additionally, this provides a good blood pressure compensation, contributing to slow the progression of vascular damage.

Endocan, a novel inflammatory marker, is upregulated in human chondrocytes stimulated with IL-1 beta

Endocan is a circulating proteoglycan, involved in immunity, inflammation, and endothelial function. It has been recently suggested as a biomarker of inflammation, increased angiogenesis, and cancer. In vitro studies have shown that endocan expression could be upregulated by inflammatory cytokines and proangiogenic molecules. High endocan levels were also shown in arthritic joint tissues and particularly in sites characterized by severe inflammation. This study was performed to evaluate endocan expression in chondrocytes stimulated with IL-ß. mRNA and related protein production were measured for endocan, TNF-α, and IL-6. NF-kB activity was also evaluated. IL-1ß treatment induced a significant upregulation of both endocan and the inflammatory parameters as well as NF-kB activity. The treatment of chondrocytes with the specific NF-kB inhibitor before IL-1ß stimulation was able to reduce endocan and the inflammatory markers over-expression. The results of our study indicated that endocan is also expressed in human chondrocytes; furthermore, consistent with previous results in other cell types and tissues, IL-1ß-induced inflammatory response involves the expression of endocan through NF-kB activation. In this context, endocan seems to be an important inflammatory marker associated with the activation of NF-kB pathway.

miR146a up-regulation is involved in small HA oligosaccharides-induced pro-inflammatory response in human chondrocytes

BACKGROUND

Small HA fragments are produced during cartilage degradation and their role seems to be preponderant during pathologies in which cartilage injury contribute to trigger and perpetuate the inflammatory mechanism. Several reports have increasingly shown that MicroRNAs (miRs), a small non-coding mRNAs are involved in the regulation of multiple biological processes, including cell proliferation and inflammation response in different pathologies, among them miR146a seems to be involved in inflammatory processes.

METHODS

Starting by these evidences we investigated the levels of miR146a and its correlation with inflammatory mediators in an experimental model of 6-mer HA-induced inflammatory response in human cultured chondrocytes.

RESULTS

Treatment of chondrocytes with 6-mer HA showed up-regulation in inflammation parameters such as TLR-4, and CD44 receptors activation, IL-6, IL-1β and MMP-13 mRNA expression and proteins production, as well as NF-kB activation. We also revealed an up-regulation of miR146a. Transfection with a miR146a mimic or miR146a inhibitor produced the following effects: chondrocytes receiving miR146a mimic and then 6-mer HA significantly reduced inflammatory cytokines and MMP-13, while exposition of chondrocytes with miR146a inhibitor and then the 6-mer HA incremented the activity of damaging cytokines and MMP13. Expression of CD44 receptor was not affected by miR-146a treatments, while TLR-4 expression and NF-kB activation were modified.

CONCLUSIONS

We concluded that up-regulation of miR146a occurred in 6-mer HA-induced inflammation response may reduce the inflammatory cascade by modulating TLR-4 and NF-kB activation.

GENERAL SIGNIFICANCE

These results could be useful in develop new therapeutic strategies with the aim to reduce OA and RA incidence.

Hyaluronan oligosaccharides modulate inflammatory response, NIS and thyreoglobulin expression in human thyrocytes

Autoimmune thyroid diseases, such as Hashimoto's thyroiditis, are characterized by lymphocytic infiltration and altered function of the thyroid. During inflammation, it has been reported a decreased expression in Tg and NIS, accompanied by an increase in HA production that accumulates in the gland. HA fragments produced in different pathological states can modulate gene expression in a variety of cell types and may prime inflammatory response by interacting with the TLR-2, TLR-4 and CD44 that, in turn, induce NF-kB activation finally responsible of inflammatory mediator transcription, such as IL-1β, TNF-α and IL-6. The aim of this study was to investigate the potential inflammatory effect and the biochemical pathways activated by 6-mer HA oligosaccharides in cultured human thyrocytes. 6-mer HA treatment induced up-regulation of TLR-2, TLR-4, CD44 mRNA and related protein levels, increased HA production and NF-kB activation, that in turn increased IL-1β and IL-6 concentrations. Instead, we found evidence of an opposite effect on thyroid specific-gene Tg and NIS, that were decreased after 6-mer HA addition. Thyrocytes exposition to specific blocking antibodies for TLR-2, TLR-4 and CD44 abolished up-regulation of NF-κB activation and the consequent pro-inflammatory cytokine production, while restored Tg and NIS levels. A further goal of this study was demonstrate that also other LMW HA have pro inflammatory proprieties. These data suggest that HA fragments, through the involvement of TLR-2, TLR-4 and CD44 signaling cascade, contribute to prime the inflammatory response in thyrocytes and, by reducing the expression of thyroid-specific genes, could promote the loss of function of gland such as in Hashimoto's thyroiditis.

Biglycan and atherosclerosis: Lessons from high cardiovascular risk conditions

Atherosclerosis (ATH) is a chronic, dynamic, evolutive process involving morphological and structural subversion of artery walls, leading to the formation of atherosclerotic plaques. ATH generally initiates during the childhood, occurring as a result of a number of changes in the intima tunica and in the media of arteries. A key event occurring during the pathobiology of ATH is the accumulation of lipoproteins in the sub-intimal spaces mediated by extracellular matrix (ECM) molecules, especially by the chondroitin sulfate/dermatan sulfate (CS/DS) -containing proteoglycans (CS/DSPGs). Among them, the proteoglycan biglycan (BGN) is critically involved in the onset and progression of ATH and evidences show that BGN represents the missing link between the pro-atherogenic status induced by both traditional and non-traditional cardiovascular risk factors and the development and progression of vascular damage. In the light of these findings, the role of BGN in dyslipidemia, hypertension, cigarette smoking, diabetes, chronic kidney disease and inflammatory status is briefly analyzed and discussed in order to shed new light on the underlying mechanisms governing the association between BGN and ATH.

Hyaluronan Fragmentation During Inflammatory Pathologies: A Signal that Empowers Tissue Damage

The mechanisms that modulate the response to tissue injury are not fully understood. Abnormalities in the repair response are associated with a variety of chronic disease states characterized by inflammation, followed subsequently by excessive ECM deposition. As cell-matrix interactions are able to regulate cellular homeostasis, modification of ECM integrity appears to be an unspecific factor in promoting the onset and progression of inflammatory diseases. Evidence is emerging to show that endogenous ECM molecules supply signals to damage tissues and cells in order to promote further ECM degradation and inflammation progression. Several investigations have been confirmed that HA fragments of different molecular sizes exhibit different biological effects and responses. In fact, the increased deposition of HA into the ECM is a strong hallmark of inflammation processes. In the context of inflammatory pathologies, highly polymerized HA is broken down into small components, which are able to exacerbate the inflammatory response by inducing the release of various detrimental mediators such as reactive oxygen species, cytokines, chemokines and destructive enzymes and by facilitating the recruitment of leukocytes. However, strategies involving the modulation of the HA fragment with specific receptors on cell surface could represent different promising effects for therapeutic scope. This review will focus on the inflammation action of small HA fragments in recent years obtained by in vivo reports.

β-Caryophyllene Mitigates Collagen Antibody Induced Arthritis (CAIA) in Mice Through a Cross-Talk between CB2 and PPAR-γ Receptors

β-caryophyllene (BCP) is a cannabinoid receptor 2 (CB2) agonist that tempers inflammation. An interaction between the CB2 receptor and peroxisome proliferator-activated receptor gamma (PPAR-γ) has been suggested and PPAR-γ activation exerts anti-arthritic effects. The aim of this study was to characterize the therapeutic activity of BCP and to investigate PPAR-γ involvement in a collagen antibody induced arthritis (CAIA) experimental model. CAIA was induced through intraperitoneal injection of a monoclonal antibody cocktail and lipopolysaccharide (LPS; 50 μg/100 μL/ip). CAIA animals were then randomized to orally receive either BCP (10 mg/kg/100 μL) or its vehicle (100 μL of corn oil). BCP significantly hampered the severity of the disease, reduced relevant pro-inflammatory cytokines, and increased the anti-inflammatory cytokine IL-13. BCP also decreased joint expression of matrix metalloproteinases 3 and 9. Arthritic joints showed increased COX2 and NF-ĸB mRNA expression and reduced expression of the PPARγ coactivator-1 alpha, PGC-1α, and PPAR-γ. These conditions were reverted following BCP treatment. Finally, BCP reduced NF-ĸB activation and increased PGC-1α and PPAR-γ expression in human articular chondrocytes stimulated with LPS. These effects were reverted by AM630, a CB2 receptor antagonist. These results suggest that BCP ameliorates arthritis through a cross-talk between CB2 and PPAR-γ.

Serglycin as part of IL-1β induced inflammation in human chondrocytes

Serglycin (SRGN) is an intracellular proteoglycan produced and secreted by several cell types. The increased expression of SRGN was associated with greater aggressiveness in cancer and inflammation. In this study, we demonstrated that SRGN is increased in human chondrocytes after IL-β stimulation. Furthermore, we found that secreted SRGN was able to bind the CD44 receptor thus participating in the extension of the inflammatory response. Using SRGN knockdown cells we observed a significantly decrease in specific inflammatory markers and NF-kB activation. Similar results were observed by blocking the CD44 receptor. These data provide further evidences for a direct involvement of SRGN in the mechanisms regulating the non-infectious chondrocytes damage, and the consequent joint inflammation and cartilage destruction in arthritis.

Hyaluronan fragments produced during tissue injury: A signal amplifying the inflammatory response

Inflammation is a complex mechanism that plays a key role during diseases. Dynamic features of the extracellular matrix (ECM), in particular, during phases of tissue inflammation, have long been appreciated, and a great deal of several investigations has focused on the effects of ECM derivatives on cell function. It has been well defined that during inflammatory and tissue injury, ECM components were degraded. ECM degradation direct consequence is the loss of cell homeostasis, while a further consequence is the generation of fragments from larger precursor molecules. These bio-functional ECM shred defined matrikines as capable of playing different actions, especially when they function as powerful initiators, able to prime the inflammatory mechanism. Non-sulphated glycosaminoglycan hyaluronan (HA) is the major component of the ECM that undergoes specific modulation during tissue damage and inflammation. HA fragments at very low molecular weight are produced as a result of HA depolymerization. Several evidence has considered the plausibility that HA breakdown products play a modulatory action in the sequential stages of inflammation, although the effective mechanism of these HA derivative compounds act is not completely defined. This review will focus on the pro-inflammatory effects of HA fragments in recent years obtained by in vitro investigations.

Exploiting Curcumin Synergy With Natural Products Using Quantitative Analysis of Dose-Effect Relationships in an Experimental In Vitro Model of Osteoarthritis

Introduction: Drug combination is widely used to treat chronic inflammatory diseases. A similar strategy might be worth of interest to design plant-derived natural products to treat inflammatory conditions. Curcumin is a natural phenolic compound which shares anti-inflammatory activity with both flavocoxid, a flavonoid mixture of baicalin and catechin, and β-caryophyllene, a bicyclic sesquiterpene. The aim of this study was to investigate the synergy potential of curcumin with both flavocoxid and β-caryophyllene in human articular chondrocytes triggered with lipopolysaccharide (LPS), in an experimental in vitro model of osteoarthritis. Materials and Methods: Human articular chondrocytes were stimulated with LPS alone or in combination with different treatments. Total RNA was extracted 4 h after treatment to study interleukin 1β (IL-1β), NF-κB, and STAT3 mRNA expression. A drug combination study was designed choosing 5 doses to demonstrate a synergistic effect of compounds, according to Chou and Talalay method. A median-effect equation was applied and finally, the combination index (CI) was used to clarify the nature of the compounds interaction (synergistic versus additive versus antagonistic inhibitory effects); CI < 1, CI = 1, and CI > 1 indicated synergistic, additive, and antagonistic effects, respectively. Results: LPS prompted IL-1β expression. Curcumin, flavocoxid and β-caryophyllene suppressed IL-1β expression with different IC₅₀. A synergistic action for the reduction of the inflammatory phenotype in human chondrocytes was observed for the combination curcumin-flavocoxid with a percentage from 10% to 90%, and for the combination curcumin-β-caryophyllene from 50% to 90%. IC₅₀ doses of either flavocoxid, β-caryophyllene and curcumin alone or in combination were safe and did not affect cell vitality. Moreover, the same IC₅₀ doses reduced the transcription factors NF-κB and STAT3 mRNA expression and interestingly the effects of the combinations were greater than the natural products alone, thus suggesting that the site where the synergy takes place could be at the signal transduction level. Discussion: The results suggest that curcumin synergizes with either flavocoxid or β-caryophyllene, exerting an anti-inflammatory activity and thus strongly suggesting the potential of a dual combination of these compounds for the management of osteoarthritis and unmasking a new feature of these natural products.

Endothelial progenitor cells and rheumatic disease modifying therapy

Rheumatic diseases are associated with accelerated atherosclerosis and with increased risk of cardiovascular morbidity and mortality. The mechanisms underlying the higher prevalence of cardiovascular disease are not completely clarified, but it is likely that a pivotal role is played by vascular inflammation and consequently to altered vascular endothelium homeostasis. Also, high prevalence of traditional risk factors, proatherogenic activation and endothelial dysfunction further contribute to vascular damage. Circulating endothelial progenitor cells (EPCs) can restore dysfunctional endothelium and protect against atherosclerotic vascular disease. However, abnormalities in number and function of these cells in patients with rheumatic condition have been extensively reported. During the last years, growing interest in the mechanisms of endothelial renewal and its potential as a therapy for CVD has been shown; in addition, pioneering studies show that EPC dysfunction might be improved with pharmacological strategies. However, how to restore EPC function, and whether achieving this aim may be effective in preventing cardiovascular complications in rheumatic disease, remain to be established. In this review we report an overview on the current stand of knowledge on the effect of pharmaceutical and lifestyle intervention in improving EPCs number and function in rheumatic disease.

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.

The proteoglycan biglycan mediates inflammatory response by activating TLR-4 in human chondrocytes: Inhibition by specific siRNA and high polymerized Hyaluronan

Cartilage degeneration are hallmarks of wear, tear, mechanical and inflammatory damage of the joint cartilage. Tissue degradation as well as compromising the integrity and function of the organ, produces different intermediates, directly able to stimulate further inflammatory effect, therefore, amplifying the inflammation response. Biglycan is a soluble component of the extracellular matrix that is released during tissue injury. It has been reported that released biglycan is an endogenous ligand for TLR-2/4 in some cell type. We studied the role of biglycan in an experimental model of biglycan-induced inflammatory response in human chondrocytes and the effect of high polymerized HA on reducing its activity. Exposition of chondrocytes to LPS generated cell injury, including high levels of biglycan. Chondrocyte treatment with biglycan produces a high mRNA expression of several detrimental inflammation mediators such as IL-1β, IL-6, MMP-13, and IL-17, as well as NF-kB and TLR-4 activation. Administration of high polymerized HA to chondrocytes exposed to biglycan was able to attenuate the inflammatory response by decreasing the expression of the inflammatory mediators. Involvement of the TLR-4 in the mediation of the biglycan action was confirmed using a specific silent agent (siRNA). Taken together, these data could be used to develop new anti-inflammatory approaches.

Hyaluronan in experimental injured/inflamed cartilage: In vivo studies

Joint disease is characterized by an imbalance between the synthesis and degradation of articular cartilage and subchondral bone accompanied by capsular fibrosis, osteophyte formation and varying degrees of inflammation of the synovial membrane. Many animal models have been developed to study arthritis and osteoarthritis that enable experimental conditions, diet and environmental risk factors to be carefully controlled. Animal-based studies have demonstrated the positive effects of exogenous HA on the preservation of joint cartilage in different models of arthritis and osteoarthritis. Although many promising effects of exogenous HA have been reported, there remains uncertainty as to its effectiveness in reversing cartilage injury and other manifestations of joint diseases because of difficulties in interpreting and unifying the results of these studies. A review of the literature of the last decade was conducted to report the results and to determine what we have learned from animal models in relation to joint inflammation induced by experimental models and HA treatment.

Hyaluronan in the experimental injury of the cartilage: biochemical action and protective effects

INTRODUCTION

Our knowledge of extracellular matrix (ECM) structure and function has increased enormously over the last decade or so. There is evidence demonstrating that ECM provides signals affecting cell adhesion, shape, migration, proliferation, survival, and differentiation. ECM presents many domains that become active after proteolytic cleavage. These active ECM fragments are called matrikines which play different roles; in particular, they may act as potent inflammatory mediators during cartilage injury.

FINDINGS

A major component of the ECM that undergoes dynamic regulation during cartilage damage and inflammation is the non-sulphated glycosaminoglycan (GAG) hyaluronan (HA). In this contest, HA is the most studied because of its different activity due to the different polymerization state. In vivo evidences have shown that low molecular weight HA exerts pro-inflammatory action, while high molecular weight HA possesses anti-inflammatory properties. Therefore, the beneficial HA effects on arthritis are not only limited to its viscosity and lubricant action on the joints, but it is especially due to a specific and effective anti-inflammatory activity. Several in vitro experimental investigations demonstrated that HA treatment may regulate different biochemical pathways involved during the cartilage damage. Emerging reports are suggesting that the ability to recognize receptors both for the HA degraded fragments, whether for the high-polymerized native HA involve interaction with integrins, toll-like receptors (TLRs), and the cluster determinant (CD44). The activation of these receptors induced by small HA fragments, via the nuclear factor kappa-light-chain enhancer of activated B cell (NF-kB) mediation, directly or other different pathways, produces the transcription of a large number of damaging intermediates that lead to cartilage erosion.

CONCLUSIONS

This review briefly summarizes a number of findings of the recent studies focused on the protective effects of HA, at the different polymerization states, on experimental arthritis in vitro both in animal and human cultured chondrocytes.

6-Mer Hyaluronan Oligosaccharides Modulate Neuroinflammation and α-Synuclein Expression in Neuron-Like SH-SY5Y Cells

Several studies have shown the degradation of the extracellular matrix at the site of neuroinflammation and increased release of degradation products of glycosaminoglycans. Among these, low molecular weight fragments of hyaluronan (HA) may play a key role in the events leading to neuroinflammation and/or neuronal degeneration. Small HA fragments are able to induce inflammation by stimulating both TLR-2 and TLR-4 as well as CD44 receptors. This stimulation culminates in the nuclear translocation of NF-kB that in turn induces the production of pro-inflammatory intermediates such as TNF-α and IL-1β. The potential of HA fragments, as mediators of inflammation, it has been poorly investigated in neuron-like SH-SY5Y cells so the aim of this study was to investigate the neuroinflammatory effects of very small HA oligosaccharides, the involvement of TLR-2, TLR-4, and CD44 and the production of α-synuclein in such cells. The addition of HA fragments to cell cultures up-regulated TLR-2, TLR-4, and CD44 levels, induced NF-kB activity and increased both TNF-α and IL-β as well as α-synuclein production. On blocking the activity of TLR-2, TLR-4, and CD44 the levels of inflammatory parameters and of α-synuclein were significantly reduced. Since several data have shown as α-synuclein, produced from neurons, is able to initiate ex novo or to maintain an existing neuroinflammatory response, which has been suggested as one of the principal components involved in neurodegenerative pathologies, as PD, we suggest that HA pathways should be given careful consideration when devising future anti-neuroinflammatory strategies to defend against the onset of neurodegenerative disorders. J. Cell. Biochem. 117: 2835-2843, 2016. © 2016 Wiley Periodicals, Inc.

Beta-arrestin 1 is involved in the catabolic response stimulated by hyaluronan degradation in mouse chondrocytes

Beta-arrestin-1 (β-arrestin-1) is an adaptor protein that functions in the termination of G-protein activation and seems to be involved in the mediation of the inflammatory response. Interleukin-1β (IL-1β) elicits the expression of inflammatory mediators through a mechanism involving hyaluronan (HA) degradation, thereby contributing to toll-like receptor 4 (TLR-4) and CD44 activation. Stimulation of both receptors induces nuclear factor kappaB (NF-kB) activation that, through transforming-growth-factor-activated-kinase-1 (TAK-1), in turn stimulates the inflammatory mediators of transcription. As β-arrestin-1 seems to play an inflammatory role in arthritis, we have investigated the involvement of β-arrestin-1 in a model of IL-1β-induced inflammatory response in mouse chondrocytes. IL-1β treatment significantly increases chondrocytes TLR-4, CD44, β-arrestin-1, TAK-1, and serine/threonine kinase (AKT) mRNA expression and related protein levels. NF-kB is also markedly activated with consequent tumor-necrosis-factor-alpha, interleukin-6, and inducible-nitric-oxide-synthase up-regulation. Treatment of IL-1β-stimulated chondrocytes with β-arrestin-1 and/or AKT and/or TAK-1-specific inhibitors significantly reduces all parameters, although the inhibitory effect exerted by TAK-1-mediated pathways is more effective than that of β-arrestin-1. β-Arrestin-1-induced NF-kB activation is mediated by the AKT pathway as shown by IL-1β-stimulated chondrocytes treated with AKT inhibitor. Finally, a specific HA-blocking peptide (Pep-1) has confirmed the inflammatory role of degraded HA as a mediator of the IL-1β-induced activation of β-arrestin-1.

Evaluation of putative cytotoxic activity of crude extracts from Onopordum acanthium leaves and Spartium junceum flowers against the U-373 glioblastoma cell line

Crude hydromethanolic (80% methanol) extracts produced by maceration of Onopordum acanthium leaves and Spartium junceum flowers were tested for cytotoxic effects against glioblastoma U-373 tumour cells. Onopordum acanthium extract was found to be ~5 times more cytotoxic than Spartium junceum (IC50 values of 309 and 1602μg/ml, respectively). Similar to most chemotherapeutic agents killing through the intrinsic pathway, Onopordum killed the cells via apoptosis, which was confirmed by the activation of caspase-3. Spartium exerted its weak cytotoxic effect, presumably by a caspase-independent, non-apoptotic form of necrotic-like programmed cell death. Onopordum acanthium is considered a promising plant for the researchers investigating putative biological activities, particularly antitumour and immune-related activity.

Inhibition of small HA fragment activity and stimulation of A2A adenosine receptor pathway limit apoptosis and reduce cartilage damage in experimental arthritis

Recent studies have found that the inactivation of small hyaluronan (HA) fragments originating from native HA during inflammation reduced the inflammatory response in models of experimental arthritis. The stimulation of adenosine receptors A2A reduced inflammation by inhibiting NF-kB activation. The combination of both treatments was significantly more effective than either of the individual treatments. The aim of this study was to further investigate the effects of a combined treatment using the HA inhibitor Pep-1 and a selective A2AR agonist (CV-1808) on the structure and ultrastructure of the articular cartilage and on apoptosis in a model of collagen-induced arthritis (CIA) in mice. Arthritic mice were treated with Pep-1 and/or CV-1808 intraperitoneally daily for 20 days. At day 35, the hind limbs were processed for light microscopy (hematoxylin/eosin and Safranin-O-Fast Green) and for transmission and scanning electron microscopy. CIA increased IL-6, caspase-3 and caspase-7 mRNA expression and the related protein levels in arthritic articular cartilage, and significantly increased concentrations of Bcl-2-associated X protein (Bax), while B cell-lymphoma-2 protein (Bcl-2) was markedly reduced. The combined Pep-1/CV-1808 treatment significantly reduced CIA injury, particularly at the highest doses, demonstrated by the presence of Safranin-O-positive cartilage, with a smooth surface and normal chondrocytes in the superficial, intermediate and deep zones. Morphological data and histological scoring were strongly supported by the reduction in inflammation and apoptotic markers. The results further support the role of HA degradation and A2A receptors in arthritis.

Beta-arrestin-2 negatively modulates inflammation response in mouse chondrocytes induced by 4-mer hyaluronan oligosaccharide

Beta-arrestin-2 is an adaptor protein that terminates G protein activation and seems to be involved in the modulation of the inflammatory response. Small hyaluronan (HA) fragments, such as 4-mer HA oligosaccharides, are known to interact with the toll-like receptor-4 (TLR-4) with consequent activation of the nuclear factor kappaB (NF-kB) that in turn stimulates the inflammation response. NF-kB activation is mediated by different pathways, in particular by the transforming growth factor-activated kinase-1 (TAK-1). Conversely, increased levels of protein kinase A (PKA), induced by cyclic adenosine monophosphate (cAMP), seem to inhibit NF-kB activation. We studied the involvement and role of beta-arrestin-2 in mouse chondrocytes stimulated with 4-mer HA fragments. The exposure of chondrocytes to 4-mer HA produced a significant up-regulation in TLR-4, cAMP, beta-arrestin-2, TAK-1, protein 38 mitogen-activated protein kinase (p38MAPK), and PKA, both in terms of mRNA expression and of the related protein levels. NF-kB was significantly activated, thereby producing the transcription of pro-inflammatory mediators, including tumor necrosis factor alpha, interleukin-6, and interleukin-17. The treatment of 4-mer HA-stimulated chondrocytes with antibodies against beta-arrestin-2 and/or a specific PKA inhibitor, significantly increased the inflammatory response, while the treatment with a specific p38MAPK inhibitor significantly reduced the inflammatory response. Interestingly, the anti-inflammatory action exerted by beta-arrestin-2 appeared to be mediated in part through the direct inhibition of p38MAPK, preventing NF-kB activation, and in part through cAMP and PKA activation primed by G protein signaling, which exerted an inhibitory effect on NF-kB. Taken together, these results could be useful for future anti-inflammatory strategies.

Inhibition of the hyaluronan oligosaccharides inflammatory response: reduction of adenosine 2A receptor activation by EPAC and PKA

The aim of this study was to investigate the involvement of exchange proteins directly activated by cyclic adenosine (ADO) monophosphate (EPAC) in 4-mer hyaluronan (HA) oligosaccharide-induced inflammatory response in mouse normal synovial fibroblasts (NSF). Treatment of NSF with 4-mer HA increased Toll-like receptor-4, TNF-alpha and IL-1beta mRNA expression and of the related proteins, as well as nuclear factor kappaB (NF-kB) activation. Addition to NSF, previously stimulated with 4-mer HA oligosaccharides, of ADO significantly reduced NF-kB activation, TNF-alpha and IL-1beta expression. The pre-treatment of NSF with cyclic ADO monophosphate and/or PKA and/or EPAC-specific inhibitors significantly inhibited the anti-inflammatory effect exerted by ADO. In particular, the EPAC inhibitor reduced the ADO effect to a major extent than the PKA inhibitor. These results mean that both PKA and EPAC pathways are involved in ADO-induced NF-kB inhibition although EPAC seems to be more involved than PKA.

MiRNome expression is deregulated in the peripheral lymphoid compartment of multiple myeloma

MicroRNAs (miRNAs) are short non-coding RNAs involved in the regulation of gene expression. Selected groups of miRNAs are differentially expressed in various types of cancers. Alterations in miRNAs gene expression have been shown in cells from the B-cell malignancy, multiple myeloma (MM). However, although MM is a disease of plasma cells, abnormalities have been detected in the peripheral blood of the patients. The goal of our study was to analyse the entire miRNome in peripheral lymphocytes of MM patients using reverse transcription quantitative polymerase chain reaction. Using in silica analysis, we also evaluated some of the most interesting and significant pathways. Analysis revealed that MM samples had a distinct miRNA profile compared to the controls. This resulted in the identification of 203 miRNAs, 85 of which were over-expressed and 118 under-expressed. Of these, 184 possessed validated or highly predicted mRNA targets. We identified 12 354 mRNA targets of the transcriptome: 36·4% of the related proteins are involved in death processes while the 21% are required for growth and cell proliferation. We have demonstrated that miRNAs are differentially expressed in the peripheral blood of MM patients compared to controls, affecting some pathways involved in the anti-apoptotic process, cell proliferation and maybe anti-angiogenesis.

Combined treatment with hyaluronan inhibitor Pep-1 and a selective adenosine A2 receptor agonist reduces inflammation in experimental arthritis

Investigations have suggested degradation of native hyaluronan (HA) into small oligosaccharides as being involved in the development and progression of inflammatory diseases, particularly rheumatoid arthritis (RA). Inflammatory responses occur by modulating the TLR4 and 2, and the CD44 natural HA receptor. As reported recently, the adenosine A2 receptor (A2AR) plays an important anti-inflammatory role in arthritis. TLR4, TLR2 and CD44 stimulation activate NF-κB, which stimulates the production of pro-inflammatory cytokines and other mediators. In contrast, A2AR stimulation inhibits NF-κB activation. The aim of this study was to investigate the effect of combined treatment of HA inhibitor Pep-1 and a selective A2AR agonist (CV-1808) in collagen-induced arthritis (CIA) in mice. Arthritis was induced via intradermal injection of bovine collagen-II. Mice were treated with Pep-1 plus CV-1808 intraperitoneally daily for 20 d. CIA increased TLR4, TLR2, CD44 and A2AR mRNA expression and the related proteins in the joint cartilage of arthritic mice, where significantly increased concentrations were of TNF-α, IL-1-β, IL-17, matrix metalloprotease-13 and inducible nitric oxide synthase. Pep-1 with CV-1808 treatment significantly reduced CIA damage and all the up-regulated biochemical parameters. These reductions were supported by microscopic analysis and synovial fluid HA levels.

The SOD mimic MnTM-2-PyP(5+) reduces hyaluronan degradation-induced inflammation in mouse articular chondrocytes stimulated with Fe (II) plus ascorbate

In pathological conditions, oxidative burst generates hyaluronan (HA) fragmentation with a consequent increase in the number of small HA oligosaccharides. These fragments are able to stimulate an inflammatory response in different cell types by activating the CD44 and the toll-like receptors 4 (TLR-4) and 2 (TLR-2). The stimulation of CD44 and TLRs in turn activates the NF-kB which induces the production of several pro-inflammatory mediators that amplify and perpetuate inflammation. We aimed to study the antioxidant effect of the SOD mimic, synthetic manganese porphyrin, Mn(III) 5,10,15,20-tetrakis(N-methylpyridinium-2-yl)porphyrin (MnTM-2-PyP(5+)) on preventing HA degradation in mouse articular chondrocytes stimulated with Fe (II) plus ascorbate. Fe (II) plus ascorbate stimulation induced oxidative burst confirmed by high levels of hydroxyl radical/peroxynitrite production, increased lipid peroxidation and HA degradation. HA fragments highly induced mRNA expression and the related protein production of CD44, TLR-4 and TLR-2, NF-kB activation and significantly up-regulated the inflammatory cytokines, tumor necrosis factor alpha (TNF-alpha), interleukin-1beta (IL-1beta), and other pro-inflammatory mediators, i.e. matrix metalloprotease 13 (MMP-13) and inducible nitric oxide synthase (iNOS). Treatment of cells with MnTM-2-PyP(5+)was able to attenuate oxidative burst, HA degradation and NF-kB activation, and markedly decreased mRNA expression of CD44, and TLRs and the related protein synthesis, as well as the levels of up-regulated inflammatory mediators. Adding a specific HA-blocking peptide (PEP-1) to cells significantly reduced all the inflammatory parameters up-regulated by Fe (II) plus ascorbate, and increased MnTM-2-PyP(5+) activity. These findings suggest that HA degradation plays a key role in the initial inflammatory response of cartilage and antioxidants and could be a useful tool to prevent the propagation of this mechanism.

4-mer hyaluronan oligosaccharides stimulate inflammation response in synovial fibroblasts in part via TAK-1 and in part via p38-MAPK

4-mer hyaluronan (HA) oligosaccharides stimulate pro-inflammatory effects in different cell types by interacting with both the toll-like receptor-4 (TLR-4) and -2 (TLR-2). This interaction induces the activation of the transforming growth factor activated kinase-1 (TAK-1) that activates the nuclear factor kappaB (NF-kB) either directly and/or through the activation of p38-mitogen-activated protein kinase (p38-MAPK). This in turn induces the transcription of proinflammatory mediators that prime inflammation. Our aim was to investigate the involvement of TAK-1 and p38-MAPK in 4-mer HA oligosaccharide-induced inflammatory response in mouse synovial fibroblasts obtained from normal DBA/J1 mice (NSF) and from mice subjected to collagen-induced arthritis (CIA). Treatment of NSF and rheumatoid arthritis synovial fibroblasts (RASF) with 4-mer HA showed a marked up-regulation of TLR-4, TLR-2, TAK-1 and p38-MAPK mRNA expression and of the related proteins, as well as NF-kB activation. High levels were also detected of TNF-α, IL- 1β, MMP-13 and iNOS. Treatment of NSF and RASF, previously stimulated with 4-mer HA oligosaccharides, with TAK- 1 and/or p38-MAPK specific inhibitors significantly reduced all the parameters, although the inhibitory effect of p38- MAPK was less effective than that of TAK-1. The addition of CD44 antibody to both NSF and RASF showed that CD44 was not involved in 4-mer HA-induced inflammation.

Protein kinase a mediated anti-inflammatory effects exerted by adenosine treatment in mouse chondrocytes stimulated with IL-1β

Hyaluronan (HA) fragments produced by degradation of native highly polymerized HA during inflammation may exacerbate proinflammatory responses in different pathologies. In contrast, the nucleoside adenosine (ADO) interacting with cell surface adenosine receptors A(2A) R, A(2B) R, A(1,) and A(3) , acts as endogenous modulator of the inflammation. The engagement of high-affinity A(2A) R by ADO activates a pathway leading to increased cAMP production. Elevated levels of cAMP associate with the activation of protein kinase A (PKA) able to inhibit NF-kB, hence exerting anti-inflammatory activity. In this study the effect of ADO treatment in normal murine chondrocytes stimulated with interleukin-1beta (IL-1beta) was investigated. mRNA and related protein levels were measured for enzymes, receptors and pro-inflammatory cytokines TNF-alpha, IL-6 and Il-18. IL-1beta stimulation significantly up-regulated HA levels, its fragmentation, cAMP, PKA, cytokine levels, and activated NF-kB. ADO treatment increased cAMP and PKA levels, while reduced NF-kB activation and cytokine levels. HA inhibition by specific synthetic HA blocking peptide (Pep-1) reduced IL-1beta action but not ADO activity. While A(2A) R inhibition by specific small interference RNA (siRNA) increased inflammation and decreased cAMP and PKA levels. This study suggests that HA is partially responsible for the up-regulation of proinflammatory cytokines in chondrocytes and that endogenous/exogenous ADO may reduce inflammation via PKA.

6-Mer hyaluronan oligosaccharides increase IL-18 and IL-33 production in mouse synovial fibroblasts subjected to collagen-induced arthritis

Hyaluronan (HA) oligosaccharides stimulate pro-inflammatory responses in different cell types by modulating both cluster determinant 44 (CD44) and TLR4. The activation of these receptors is also mediated by collagen-induced arthritis (CIA) that, via two different pathways, culminates in the liberation of NF-κB. This then stimulates the production of pro-inflammatory cytokines, including IL-18 and IL-33, that are greatly involved in rheumatoid arthritis. The aim of this study was to investigate the effects of 6-mer HA oligosaccharides on mouse synovial fibroblasts obtained from normal DBA/J1 mice or mice subjected to CIA. Compared with normal synovial fibroblasts (NSF), rheumatoid arthritis synovial fibroblasts (RASF) showed no up-regulation of CD44 and TLR4 mRNA expression and the related proteins, as well as no activation of NF-κB. Very low levels of both mRNA and related proteins were also detected for IL-18 and IL-33. Treatment of NSF and RASF with 6-mer HA oligosaccharides significantly increased all the parameters in both fibroblast groups, although to a greater extent in RASF. The addition of hyaluronan binding protein to both NSF and RASF inhibited HA activity and was able to reduce the effects of 6-mer HA oligosaccharides and the consequent inflammatory response.

The stimulation of adenosine 2A receptor reduces inflammatory response in mouse articular chondrocytes treated with hyaluronan oligosaccharides

The adenosine 2A receptor (A(2A)R) is greatly involved in inflammation pathologies such as rheumatoid arthritis. By interacting with A(2A)R, the purine nucleoside adenosine acts as a potent endogenous inhibitor of the inflammatory process in a variety of tissues. Hyaluronan (HA) fragments act to prime inflammation via CD44 and the toll-like receptor 4 (TLR-4). The aim of this study was to investigate whether the inhibition/stimulation of A(2A)R modulates the inflammation cascade primed by small HA fragments in mouse articular chondrocytes. 6-mer HA treatment induced up-regulation of CD44, TLR4 and A(2A)R mRNA expression and the related protein levels, and NF-kB activation, that in turn increased TNF-α, IL-1β, and IL-6 and production. Treatment with a selective (2)A adenosine receptor agonist (2-phenylaminoadenosine) enhanced A(2A)R increase, as well as the inhibition of CD44 and TLR4 activity using two specific antibodies abolished up-regulation of CD44 and TLR4, and significantly reduced, especially by antibody inhibition, NF-kB activation and pro-inflammatory cytokine production. Furthermore, the exposure of chondrocytes to A(2A)R specific interference mRNA (A(2A)R siRNA) enhanced HA 6-mer induced NF-kB activation and inflammatory cytokine increase. Finally, the use of an exchange protein activated by cAMP (EPAC) siRNA and a specific PKA inhibitor showed a predominant EPAC involvement in the mediation of the anti-inflammatory activity exerted by A(2A)R stimulation. These data suggest that HA depolymerization occurring during inflammation contributes to priming of the inflammatory cascade, while endogenous adenosine, by exerting anti-inflammatory response via A(2A)R, could be a modulatory mechanism that attempts to attenuate the inflammation process.

Adenosine A2A receptor activation and hyaluronan fragment inhibition reduce inflammation in mouse articular chondrocytes stimulated with interleukin-1β

Small hyaluronan (HA) fragments produced from native HA during inflammation contribute greatly to cell injury in many pathologies. HA oligosaccharides increase proinflammatory cytokine levels by activating both CD44 and toll-like receptor (TLR)-4. Stimulation of CD44 and TLR-4 then activates nuclear factor-κB, which induces the production of proinflammatory cytokines. The adenosine 2A receptor (A(2A)R) is also involved in several inflammation pathologies, and the nucleoside adenosine acts as a potent endogenous inhibitor of inflammation in various tissues by interacting with this receptor. The aim of this study was to investigate the effects of an HA-blocking peptide that inhibits the proinflammatory action of HA oligosaccharides produced during inflammation, together with a specific A(2A)R agonist in a model of normal mouse articular chondrocytes stimulated with interleukin (IL)-1β. IL-1β stimulation significantly increased mRNA expression and the related protein production of TLR-4, TLR-2, CD44 and A(2A)R in articular chondrocytes. The induced nuclear factor-κB activation was also associated with increased levels of inflammatory cytokines, including tumor necrosis factor-α and IL-6, and other inflammatory mediators, such as matrix metalloprotease-13 and inducible nitric oxide synthase. Treatment of chondrocytes with the HA-blocking peptide Pep-1 and/or a specific A(2A)R agonist (CGS-21680) significantly reduced all of the inflammatory parameters upregulated by IL-1β. These results suggest that the inflammatory response may be reduced either by blocking oligosaccharides from HA degradation or by A(2A)R stimulation.

The inhibition of hyaluronan degradation reduced pro-inflammatory cytokines in mouse synovial fibroblasts subjected to collagen-induced arthritis

Hyaluronan (HA) degradation produces small oligosaccharides that are able to increase pro-inflammatory cytokines in rheumatoid arthritis synovial fibroblasts (RASF) by activating both CD44 and the toll-like receptor 4 (TLR-4). CD44 and TLR-4 stimulation in turn activate the NF-kB that induces the production of pro-inflammatory cytokines. Degradation of HA occurs via two mechanisms: one exerted by reactive oxygen species (ROS) and one controlled by different enzymes in particular hyaluronidases (HYALs). We aimed to investigate the effects of inhibiting HA degradation (which prevents the formation of small HA fragments) on synovial fibroblasts obtained from normal DBA/J1 mice (NSF) and on synovial fibroblasts (RASF) obtained from mice subjected to collagen induced arthritis (CIA), both fibroblast types stimulated with tumor necrosis factor alpha (TNF-α). TNF-α stimulation produced high mRNA expression and the related protein production of CD44 and TLR-4 in both NSF and RASF, and activation of NF-kB was also found in all fibroblasts. TNF-α also up-regulated the inflammatory cytokines, interleukin-1beta (IL-1beta) and interleukin-6 (IL-6), and other pro-inflammatory mediators, such as matrix metalloprotease-13 (MMP-13), inducible nitric oxide synthase (iNOS), as well as HA levels and small HA fragment production. Treatment of RASF with antioxidants and specific HYAL1, HYAL2, and HYAL3 small interference RNA (siRNAs) significantly reduced TLR-4 and CD44 increase in the mRNA expression and the related protein synthesis, as well as the release of inflammatory mediators up-regulated by TNF-α. These data suggest that the inhibition of HA degradation during arthritis may contribute to reducing TLR-4 and CD44 activation and the inflammatory mediators response.

Hyaluronan in part mediates IL-1beta-induced inflammation in mouse chondrocytes by up-regulating CD44 receptors

Interleukin-1beta (IL-1beta) elicits the expression of inflammatory mediators through a mechanism involving the CD44 receptor. Hyaluronan (HA) depolymerization also contributes to CD44 activation. This study investigated the potential of HA fragments, obtained by hyaluronidase (HYAL) treatment, as mediators of CD44 activation on IL-1beta-induced inflammation in mouse chondrocytes. mRNA and related protein levels were measured for CD44, tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), matrix metalloproteinase-13 (MMP-13) and inducible nitric oxide synthase (iNOS) in chondrocytes, treated or untreated with IL-1beta, either with or without the addition of HYAL. The level of NF-kB activation was also assayed. CD44 mRNA expression was higher than controls in chondrocytes treated with IL-1beta. IL-1beta also induced NF-kB up-regulation and increased TNF-alpha, IL-6, MMP-13 and iNOS expression. Different effects resulted from HYAL treatment. Treatment of chondrocytes exposed to IL-1beta with HYAL synergistically increased the same parameters up-regulated by IL-1beta, while the same parameters were increased by HYAL in chondrocytes not exposed to IL-1beta but to a lesser extent. Specific CD44 blocking antibody and hyaluronan binding protein (HABP), which inhibit HA activity, were used to confirm CD44 to be the target of IL-1beta action through HA mediation. HA levels and molecular size further confirm the role of degraded HA. These findings suggest that IL-1beta exerts inflammatory activity via CD44 by the mediation of HA fragments derived from HA depolymerization.

Inhibition of hyaluronan synthesis reduced inflammatory response in mouse synovial fibroblasts subjected to collagen-induced arthritis

Hyaluronan (HA) fragments are able to induce inflammation by stimulating both CD44 and toll-like receptor 4 (TLR-4). CD44 and TLR-4 activation stimulates the liberation of NF-kB and pro-inflammatory cytokine responses. The aim of this study was to investigate the effects of hyaluronidase (HYAL) treatment, which depolymerises HA into small fragments, and of the addition of specific hyaluronan synthases-1, 2, and 3 small interference RNA (HASs siRNA), which silence HASs activity, on normal mouse synovial fibroblasts (NSF) and on rheumatoid arthritis synovial fibroblasts (RASF) obtained from mice subjected to collagen induced arthritis (CIA). The addition of HYAL to NSF and/or RASF significantly increased the TLR-4, CD44 and NF-kB activity, as well as the pro-inflammatory cytokines, interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6), and interleukin-33 (IL-33) in both groups, but to a greater extent in RASF. The addition to NSF and/or RASF of the HASs siRNA, which block HASs activity and therefore the availability of HA substrate for HYAL, was able to reduce HYAL effects in both NSF and RASF. Finally, the HA evaluation confirmed the increment of HA at low molecular weight after HYAL treatment.

Hyaluronan differently modulates TLR-4 and the inflammatory response in mouse chondrocytes

Hyaluronic acid (HA) may exert different action depending on its degree of polymerization. Small HA fragments induce proinflammatory responses, while highly polymerized HA exerts a protective effect in inflammatory pathologies such as rheumatoid arthritis. In both cases the toll-like receptor 4 (TLR-4) seems to be involved in the modulation of the inflammation process. The aim of this study was to investigate the influence of short HA oligosaccharides (HA 4-mers) and high molecular weight HA (HMWHA) in the inflammatory response in normal mouse chondrocytes. Messenger RNA and related protein levels were measured for TLR-4, tumor necrosis factor-alpha (TNF-alpha), interleukin-1beta (IL-1beta), interleukin-6 (IL-6), and interleukin-18 (IL-18) in cells with and without the addition of HA. NF-kB activation was also evaluated. 4-mer HA treatment produced a significant up-regulation of all parameters considered while HMWHA did not exert any activity in untreated cells although it was able to reduce the effects of 4- mers HA significantly. Specific TLR-4 small interference RNA (siRNA) was used to confirm TLR-4 as the target of HA action. This study suggests that HA may modulate proinflammatory cytokines via its different degree of polymerization and inflammatory action may be modulated as a result of the interaction between HA and TLR-4.

Polydeoxyribonucleotide reduces cytokine production and the severity of collagen-induced arthritis by stimulation of adenosine A(₂A) receptor

OBJECTIVE

Broad antiinflammatory effects following adenosine A(₂A) receptor stimulation have been demonstrated in acute inflammatory diseases, including arthritis. Polydeoxyribonucleotide (PDRN) activates the adenosine A(₂A) receptor. This study was undertaken to investigate the effects of PDRN in collagen-induced arthritis (CIA) in mice.

METHODS

Arthritis was induced in DBA/1 mice by an intradermal injection of 100 μl of bovine type II collagen in Freund's complete adjuvant. Mice were immunized a second time 21 days later. Control animals received 100 μl of a saline solution. Animals with CIA were randomized to receive one of the following: vehicle (1 ml/kg); PDRN (8 mg/kg intraperitoneally daily); 3,7-dimethyl-propargylxanthine (DMPX), a specific adenosine A(₂A) receptor antagonist (0.1 mg/kg intraperitoneally daily); or PDRN plus DMPX. The treatment was initiated immediately after the second immunization and continued to day 45. Clinical evaluation of arthritis was performed throughout the study. On day 45, the animals were killed and the severity of arthritis was evaluated histologically. Cartilage expression and circulating levels of high mobility group box chromosomal protein 1 (HMGB-1), tumor necrosis factor α (TNFα), interleukin-6 (IL-6), and IL-10 were investigated. Inflammatory cytokine production was also evaluated in stimulated human chondrocytes treated with PDRN.

RESULTS

PDRN treatment significantly ameliorated clinical signs of arthritis, improved histologic damage, reduced the cartilage expression and circulating levels of HMGB-1, TNFα, and IL-6, and enhanced IL-10 expression. The concomitant administration of DMPX and PDRN ablated the PDRN-induced protective effect in experimental arthritis. PDRN also reduced cytokine production from stimulated human chondrocytes.

CONCLUSION

Our findings indicate that PDRN may represent a new alternative for the treatment of arthritis.

Hyaluronan reduces inflammation in experimental arthritis by modulating TLR-2 and TLR-4 cartilage expression

Previous studies have reported that low molecular mass HA and highly polymerized HA respectively elicited pro- and anti-inflammatory responses by modulating the toll-like receptor 4 (TLR-4) and the TLR-2. The activation of TLR-4 and TLR-2 mediated by collagen-induced arthritis (CIA) induces the myeloid differentiation primary response protein (MyD88) and the tumor necrosis factor receptor-associated factor 6 (TRAF6), and ends with the liberation of NF-kB which, in turn, stimulates pro-inflammatory cytokine production. The aim of this study was to investigate the influence of high molecular weight HA at different concentrations on TLR-4 and TLR-2 modulation in CIA in mice. Arthritis was induced in mice via intradermal injection of an emulsion containing bovine type II collagen in complete Freund's adjuvant. Mice were treated with HA intraperitoneally daily for 30days. CIA increased TLR-4, TLR-2, MyD88 and TRAF6 mRNA expression and the related protein in the cartilage of arthritic joints. High levels of both mRNA and related protein were also detected for tumor necrosis factor alpha (TNF-α), interleukin 1-beta (IL-1-β), interleukin-17 (IL-17), matrix metalloprotease-13 (MMP-13) and inducible nitric oxide synthase (iNOS) in the joint of arthritic mice. HA treatment significantly limited CIA incidence and decreased all the parameters up-regulated by CIA. The improvement of biochemical parameters was also supported by histological analysis, plasma and synovial fluid HA levels. These results suggest that the TLR-4 and TLR-2 play an important role in the arthritis mechanism and the interaction/block of HA at high molecular mass may reduce inflammation and cartilage injury.

Systemic administration of high-molecular weight hyaluronan stimulates wound healing in genetically diabetic mice

Hyaluronic acid (HA), an essential component of the extracellular matrix, is an efficient space filler that maintains hydration, serves as a substrate for assembly of proteoglycans and is involved in wound healing. Although numerous pieces of evidence demonstrate beneficial effects in promoting wound healing in diabetes, a systemic approach has never been tested. We used an incisional wound healing model in genetically diabetic mice to test the effects of systemic injection of HA. Diabetic (n=56) and normoglycemic (n=56) mice were subjected to incision and randomized (8 groups of 7 animals each) to receive HA at different doses, 7.5, 15 and 30mg/kg/i.p., or vehicle (0.9% NaCl solution) for 12days. At the end of the experiment animals were sacrificed and skin wounds were excised for histological, biochemical and molecular analysis. Histology revealed that the most effective dose to improve wound repair and angiogenesis in diabetic mice was 30mg/kg. Furthermore HA injection (30mg/kg) improved the altered healing pattern in diabetic animals, increased skin remodeling proteins TGF-β and transglutaminase-II and restored the altered expression of cyclin B1/Cdc2 complex. Evaluation of skin from diabetic animals injected with HA revealed also an increase in HA content, suggesting that systemic injection may be able to restore the reduced intracellular HA pool of diabetic mice. Finally HA markedly improved skin mechanical properties. These promising results, if confirmed in a clinical setting, may improve the care and management of diabetic patients.

High-molecular weight hyaluronan reduced renal PKC activation in genetically diabetic mice

The cluster determinant (CD44) seems to play a key role in tissues injured by diabetes type 2. CD44 stimulation activates the protein kinase C (PKC) family which in turn activates the transcriptional nuclear factor kappa B (NF-κB) responsible for the expression of the inflammation mediators such as tumor necrosis factor alpha (TNF-α), interleukin-6 (IL-6), interleukin-18 (IL-18), inducible nitric oxide synthase (iNOS), and matrix metalloproteinases (MMPs). Regulation of CD44 interaction with its ligands depends greatly upon PKC. We investigated the effect of the treatment with high-molecular weight hyaluronan (HA) on diabetic nephropathy in genetically diabetic mice. BKS.Cg-m+/+Lepr(db) mice had elevated plasma insulin from 15 days of age and high blood sugar levels at 4 weeks. The severe nephropathy that developed was characterized by a marked increased in CD44 receptors, protein kinase C betaI, betaII, and epsilon (PKC(βI), PKC(βII), and PKCε) mRNA expression and the related protein products in kidney tissue. High levels of mRNA and related protein levels were also detected in the damaged kidney for NF-κB, TNF-α, IL-6, IL-18, MMP-7, and iNOS. Chronic daily administration of high-molecular mass HA for 2 weeks significantly reduced CD44, PKC(βI), PKC(βII), and PKCα gene expression and the related protein production in kidney tissue and TNF-α, IL-6, IL-18, MMP-7, and iNOS expression and levels also decreased. Histological analysis confirmed the biochemical data. However, blood parameters of diabetes were unchanged. These results suggest that the CD44 and PKC play an important role in diabetes and interaction of high-molecular weight HA with these proteins may reduce inflammation and secondary pathologies due to this disease.

Small hyaluronan oligosaccharides induce inflammation by engaging both toll-like-4 and CD44 receptors in human chondrocytes

Small degradation fragments of hyaluronan (HA) may stimulate an inflammatory response in a variety of tissues at the injury site. HA oligosaccharides are endogenous ligands for the cluster determinant 44 (CD44) receptor as well as for toll-like receptor 4 (TLR-4). Previous data have shown that HA fragments may induce pro-inflammatory cytokine expression by interacting with both the CD44 receptor and TLR-4. CD44 and TLR-4 stimulation activates different inflammatory pathways that culminate with the activation of the transcriptional nuclear factor kappaB (NF-kappaB) which is responsible for the expression of inflammation mediators such as tumor necrosis factor alpha (TNF-alpha), interleukin-6 (IL-6) and interleukin-1 beta (IL-1beta). The aim of this study was to investigate the inflammatory effects of very small HA oligosaccharides on both TLR-4 and CD44 involvement in normal human articular chondrocytes. Adding HA fragments to chondrocyte cultures up-regulated CD44 and TLR-4 expression, activated NF-kappaB translocation and increased the pro-inflammatory cytokines TNF-alpha, IL-6 and IL-1beta. The addition of a specific CD44 blocking antibody reduced CD44 and all inflammatory cytokine expression as well as protein production. However, cytokine expression remained significantly higher than in untreated chondrocytes. TLR-4 expression was not affected. The treatment with TLR-4 blocking antibody decreased TLR-4 and inflammatory cytokine expression, although cytokine expression was significantly higher than in control cells. CD44 expression was unaffected. The addition of both CD44 and TLR-4 blocking antibodies significantly reduced CD44, TLR-4 and inflammatory cytokine expression.

Molecular cloning and characterization of adult Sparus aurata hemoglobin genes

Among Teleosts, Sparus aurata occupies a prominent place in the gastronomic and economic fields of the Mediterranean basin and other geographic districts. The knowledge of its molecular structures and functional features, such as hemoglobin, may be helpful to understand the adaptive biochemical mechanisms that allow this fish to live under extreme conditions, including fish farming. In Sparus aurata red blood cells two different alpha and one beta hemoglobin genes have been identified. The alpha1 gene codifies a putative protein of 144 amino acids, the alpha2 gene produces a protein of 143 amino acids, and the beta gene encodes a chain of 148 amino acids. Comparative analysis of various hemoglobins indicates that allosteric regulation can be modified by the substitution of one or a few key residues. The comparison of the percentage sequence differences for alpha and beta chains in fishes indicates that evolutionary relationships between different species may be helpful to understand the mechanisms of their differentiation from other vertebrates. Hemoglobin alpha and beta chains of about 50 teleostean temperate and Antarctic fishes were analyzed to build phylogenetic trees using different algorithms: the neighbor-joining method, the maximum likelihood approach, and the Bayesian inference computation. Sparus aurata alpha chains are positioned in a paraphyletic cluster, which includes the same subunit of Chrysophrys auratus and Seriola quinqueradiata, whereas the beta chain is on an homophyletic branch with that of Chrysophrys auratus. Therefore, the phylogenetic approach suggests that both Sparus aurata hemoglobin alpha genes are paralogues and may have derived from a duplication event.

Molecular size hyaluronan differently modulates toll-like receptor-4 in LPS-induced inflammation in mouse chondrocytes

Hyaluronan (HA) action depends upon its molecular size. Low molecular weight HA elicits pro-inflammatory responses by modulating the toll-like receptor-4 (TLR-4) or by activating the nuclear factor kappa B (NF-kB). In contrast, high molecular weight HA manifests an anti-inflammatory effect via CD receptors and by inhibiting NF-kB activation. Lipopolysaccharide (LPS) -mediated activation of TLR-4 complex induces the myeloid differentiation primary-response protein (MyD88) and the tumor necrosis factor receptor-associated factor-6 (TRAF-6), and ends with the liberation of NF-kB/Rel family members. The aim of this study was to investigate the influence of HA at different MWs (low, medium, high) on TLR-4 modulation in LPS-induced inflammatory response in mouse chondrocyte cultures. Messenger RNA and related protein levels were measured for TLR-4, MyD88, and TRAF-6 in both untreated and LPS-treated chondrocytes, with and without the addition of HA (two doses for each MW). NF-kB activation, TNF-alpha and IL-1beta levels, matrix metalloprotease-13 (MMP-13), and inducible nitric oxide synthase (iNOS) gene expression were also evaluated. LPS increased all the parameters studied as well as NF-kB activation. Low MW HA upregulated TLR-4 expression, increased MyD88 and TRAF-6 and the inflammation mediators in untreated chondrocytes, and it enhanced the LPS effect in LPS-treated cells. Medium and high MW HA exerted no activity in untreated cells and only the latter reduced the LPS effects. Specific TLR-4 blocking antibody was utilised to confirm TLR-4 as the target of HA action. These findings suggest that the regulatory effect exerted by HA (at any MW) on NF-kB activation may depend upon the interaction between HA and TLR-4 and HA may thereby modulate pro-inflammatory activity via its different state of aggregation.

Differential effect of molecular mass hyaluronan on lipopolysaccharide-induced damage in chondrocytes

Hyaluronan is a biological polysaccharide that may exist in different degrees of polymerization. Several investigations reported that low molecular mass hyaluronan may have pro-inflammatory activity, while high molecular mass hyaluronan can exert beneficial effects. Starting from these data, the aim of this study was to investigate the effect of hyaluronan of different molecular mass in mouse articular chondrocyte cultures stimulated with lipopolysaccharide (LPS). Inflammation was induced in chondrocytes by acute treatment with 2.0 microg/ml LPS. High levels of tumour necrosis factor (TNF)-alpha, interleukin (IL)-1beta, IL-6, interferon (IFN)-gamma and iNOS gene expression and their related proteins were found in chondrocytes 24 h after treatment with LPS. High concentrations of NO, NF-kappaB activation, IkappaBalpha phosphorylation and apoptosis, evaluated by the increase in caspase-3 expression and its related protein amount were also produced by LPS stimulation. In contrast, LPS reduced aggrecan and collagen type II (Col2A) expression and their protein production. The treatment of chondrocytes with hyaluronan of different molecular mass produced the following effects: (i) low molecular mass hyaluronan exerted a slight inflammatory effect in untreated chondrocytes, while in LPS-treated chondrocytes it enhanced cytokine production and decreased aggrecan and Col2A compared with cells treated with LPS alone; (ii) no effect was exerted on LPS-induced apoptosis and NO production; (iii) medium molecular mass hyaluronan did not exert any inflammatory/anti-inflammatory activity in LPS-untreated/treated cells and failed to reduce apoptosis; and (iv) high molecular mass hyaluronan had no inflammatory effect in LPS-untreated cells while it was able to reduce all the detrimental effects stimulated by LPS treatment. These data confirm the multifactorial role played by hyaluronan and suggest, in particular, that hyaluronan may modulate inflammation during pathologies by its different degrees of polymerization.

Glycosaminoglycans reduced inflammatory response by modulating toll-like receptor-4 in LPS-stimulated chondrocytes

Lipopolysaccharide (LPS)-mediated activation of toll-like receptor-4 (TLR-4) complex induces specific signaling pathways, such as the myeloid differentiation primary response protein-88 (MyD88) and the tumor necrosis factor receptor-associated factor-6 (TRAF-6), involving NF-kappaB activation. As previous data reported that hyaluronan (HA) and heparan sulfate (HS) may interact with TLR-4, the aim of this study was to investigate whether glycosaminoglycans (GAGs) may modulate the TLR-4 receptor in a model of LPS-induced inflammatory cytokines in mouse chondrocytes. LPS stimulation up-regulated all inflammation parameters. The GAG treatment produced various effects: HA reduced MyD88 and TRAF-6 levels and NF-kappaB activation at the higher dose only, and exerted a very low anti-inflammatory effect; chondroitin-4-sulfate (C4S) and chondroitin-6-sulfate significantly inhibited MyD88, TRAF-6 and NF-kappaB activation, the inflammation cytokines, and inducible nitric oxide synthase; HS, like C4S, significantly reduced MyD88, TRAF-6, NF-kappaB and inflammation. Specific TLR-4 blocking antibody confirmed that TLR-4 was the target of GAG action.

Differential effect of molecular size HA in mouse chondrocytes stimulated with PMA

BACKGROUND

Hyaluronan (HA) fragments elicit the expression of inflammatory mediators through a mechanism involving the CD44 receptor. This study investigated the effects of HA at different molecular weights on PMA-induced inflammation in mouse chondrocytes.

METHODS

mRNA and related protein levels were measured for CD44, PKCdelta, PKCepsilon, TNF-alpha, IL-1beta, MMP-13, and iNOS in chondrocytes, untreated or PMA treated, with and without the addition of HA. The level of NF-kB activation was also assayed.

RESULTS

CD44, PKCdelta, and PKCepsilon mRNA expression resulted higher than controls in chondrocytes treated with PMA. PMA also induced NF-kB up-regulation and increased TNF-alpha, IL-1beta, MMP-13, and iNOS expression. HA treatment produced different effects: low MW HA up-regulated CD44 expression, increased PKCdelta and PKCepsilon levels, and enhanced inflammation in untreated chondrocytes; while in PMA-treated cells it increased CD44, PKCdelta, PKCepsilon, NF-kB, TNF-alpha, IL-1beta, MMP-13, and iNOS expression and enhanced the effects of PMA; medium MW HA did not exert action; high MW HA had no effect on untreated chondrocytes; however, it reduced PKCdelta, PKCepsilon, NF-kB activation and inflammation in PMA-stimulated cells. Specific CD44 blocking antibody was utilised to confirm CD44 as the target of HA modulation.

GENERAL SIGNIFICANCE

These data suggest that HA via CD44 may modulate inflammation via its different molecular mass.

Effect of cytokines on hyaluronan synthase activity and response to oxidative stress by fibroblasts

Cytokines such as tumour necrosis factor-alpha (TNFalpha), interferon-gamma (IFNgamma), and transforming growth factor-beta (TGF1beta) modulate hyaluronan synthase (HAS) gene expression and protein activity. The aim of this research is to evaluate the response of HAS gene expression and the related protein synthesis in fibroblasts after treatment with TNFalpha, IFNgamma and TGF1beta and to assess the potential protective effect of increased hyaluronan (HA) synthesis during oxidative stress. In this study, gene expression, protein synthesis, hyaluronan content, cell death, lactate dehydrogenase (LDH) activity, membrane lipid peroxidation and endogenous antioxidant depletion are determined for HAS1, HAS2 and HAS3. Messenger RNA (mRNA) expression and protein formation of the three HAS genes is modulated using different cytokines and various doses and correlated with increased HA synthesis. Protection of fibroblasts from injury induced by exposure to reactive oxygen species was significantly increased by TGF1beta and was associated with increased gene expression and protein formation of HAS1 and HAS2 enzymes synthesising high-molecular-weight HA. It is proposed that specific HAS enzyme activity and HA molecular weight specificity is involved in the protective mechanism.