Synovium and blood capillaries at the femoral attachment of anterior cruciate ligament are significantly abundant than those at the tibial attachment / Sinovial y capilares sanguíneos en la inserción femoral del ligamento cruzado anterior son significativamente más abundantes que los de la inserción tibial

SUMMARY: The anterior cruciate ligament (ACL) is a ligament that mainly controls the anterior and rotational mobility of the knee joint, and its surface is covered by a synovial membrane with large number of blood vessels. In general, nutritional supply to the ligament is from many capillaries in the adjacent synovium. However, statistical studies of the capillaries distributed to the ACL are insufficient. In this study, we examined cross-sectional histological images of the femoral attachment (femoral level), middle level of the tendon (middle level), and tibial attachment (tibial level) of the ACL and statistically analyzed blood capillary distribution among the three levels. The ACLs of 10 cadavers were divided into 5 equal sections, and 4mm-thick paraffin sections were made at the femoral level, middle level, and tibial level, and then hematoxylin-eosin (HE) staining were performed. The area of each transverse section was measured using Image-J 1.51n (U. S. National Institutes of Health, Bethesda, MD, USA). Fiber bundles of the ACL were relatively small and sparse in cross-sectional area at the femoral level and became larger and denser toward the tibial level. Many blood levels. The synovium at the attachment of ACL covered the surface of the fiber bundle and also penetrated deeply between the fiber bundles. In particular, the blood capillaries were densely distributed in the synovium at the femoral attachment rather than another two levels. Indeed, the number of capillaries were also most abundant in the femoral level. The cross-sectional ACL area at the femoral level is significantly small, however, the blood capillaries were most abundant. Therefore, when the ACL is injured, its reconstruction with preservation of the femoral ligamentous remnant may be clinically useful for remodeling of the grafted tendon.

El ligamento cruzado anterior (LCA) es un ligamento que controla principalmente la movilidad anterior y rotacional de la articulación de la rodilla, y su superficie está cubierta por una membrana sinovial con gran cantidad de vasos sanguíneos. En general, el suministro de nutrientes al ligamento proviene de muchos capilares en la sinovial adyacente. Sin embargo, los estudios estadísticos de los capilares distribuidos en el LCA son insuficientes. En este estudio, examinamos imágenes histológicas trans- versales de la inserción femoral (nivel femoral), el nivel medio del tendón (nivel medio) y la inserción tibial (nivel tibial) del LCA y analizamos estadísticamente la distribución de los capilares sanguíneos entre los tres niveles. Los LCA de 10 cadáveres se dividieron en 5 secciones iguales y se realizaron cortes en parafina de 4 µm de espesor a nivel femoral, medio y tibial, y luego se realizó tinción con hematoxilina-eosina (HE). El área de cada sección transversal se midió utilizando Image-J 1.51n (Institutos Nacionales de Salud de EE. UU., Bethesda, MD, EE. UU.). Los haces de fibras del LCA eran relativamente pequeños y escasos en el área de la sección transversal a nivel femoral y se hicieron más grandes y más densos hacia el nivel tibial. La membrana sinovial en la unión del LCA cubría la superficie del haz de fibras y también penetraba profundamente entre entre los haces de fibras. En particular, los capilares sanguíneos estaban densamente distribuidos en la unión femoral de la sinovial respecto a los otros dos niveles. De hecho, el número de capilares también fue más abundante a nivel femoral. El área transversal del LCA a nivel femoral era significativamente pequeña, sin embargo, los capilares sanguíneos fueron los más abundantes. Por lo tanto, cuando hay una lesión del LCA su reconstrucción con preservación del ligamento femoral remanente puede ser clínicamente útil para remodelar el tendón injertado.

Angiogenesis as a potential treatment strategy for rheumatoid arthritis.

Angiogenesis is an early and key event in the pathogenesis of rheumatoid arthritis (RA) and is crucial for the proliferation of synovial tissue and the formation of pannus. This process is regulated by both angiogenesis-stimulating factors and angiogenesis inhibitors, the basis for the "on-off hypothesis of angiogenesis." In RA, inflammation, immune imbalance, and hypoxia can further turn on the switch for blood vessel formation and induce angiogenesis. The new vasculature can recruit white blood cells, induce immune imbalance, and aggravate inflammation. At the same time, it also can provide oxygen and nutrients for the proliferating synovial tissue, which can accelerate the process of RA. The current therapies for RA mainly target the inflammatory response of autoimmune activation. Although these therapies have been greatly improved, there are still many patients whose RA is difficult to treat or who do not fully respond to treatment. Therefore, new innovative therapies are still urgently needed. This review covers the mechanism of synovial angiogenesis in RA, including the detailed process of angiogenesis and the relationship between inflammation, immune imbalance, hypoxia, and synovial angiogenesis, respectively. At the same time, in the context of the development of angiogenesis inhibition therapy for cancer, we also discuss similar treatment strategies for RA, especially the combination of targeted angiogenesis inhibition therapy and immunotherapy.

Ezrin regulates synovial angiogenesis in rheumatoid arthritis through YAP and Akt signalling.

This study aimed to investigate the role and regulatory mechanisms of Ezrin in synovial vessels in rheumatoid arthritis (RA). Synovial tissues were obtained from people with osteoarthritis people and patients with RA patients. We also used an antigen-induced arthritis (AIA) mice model by using Freund's adjuvant injections. Ezrin expression was analysed by immunofluorescence and immunohistochemical staining in synovial vessels of patients with RA and AIA mice. We investigated the role of Ezrin on vascular endothelial cells and its regulatory mechanism in vivo and in vitro by adenoviral transfection technology. Our results suggest a role for the Ezrin protein in proliferation, migration and angiogenesis of vascular endothelial cells in RA. We also demonstrate that Ezrin plays an important role in vascular endothelial cell migration and tube formation through regulation of the Hippo-yes-associated protein 1 (YAP) pathway. YAP, as a key protein, can further regulate the activity of PI3K/Akt signalling pathway in vascular endothelial cells. In AIA mice experiments, we observed that the inhibition of Ezrin or of its downstream YAP pathway can affect synovial angiogenesis and may lead to progression of RA. In conclusion, Ezrin plays an important role in angiogenesis in the RA synovium by regulating YAP nuclear translocation and interacting with the PI3K/Akt signalling pathway.

Longitudinal Changes in Knee Joint Synovial Vascularity in a Rabbit Model of Rheumatoid Arthritis: Quantification Using Power Doppler Ultrasound and Contrast-Enhanced Ultrasound.

We studied a rabbit model of rheumatoid arthritis (RA) to examine the time course of changes in synovial neovascularization based on quantitative power Doppler ultrasound and contrast-enhanced ultrasound (CEUS). Twenty-five male New Zealand rabbits were in the ovalbumin-induced arthritis (OIA) group, and 5 were in the control group. Both rear knee joints of all rabbits were examined using conventional US and CEUS over 16 weeks. The knee synoviums of OIA rabbits were sampled by US-guided biopsy, and expression of CD31 and vascular endothelial growth factor (VEGF) was determined by immunohistochemistry. The correlation of joint damage based on multimodal US with microvessel density (CD31 positivity) and VEGF expression at different times was analyzed. OIA rabbits had increased synovial expression of CD31 and VEGF from weeks 6 to 12 (p < 0.01). During the early stage of CEUS enhancement, "dot enhancement" was more common at weeks 6 and 8, and "stripe enhancement" was more common at weeks 12 and 16 (p < 0.05). There were significant positive correlations of synovial CD31 and VEGF expression with power Doppler image grade, CEUS grade and peak intensity (p < 0.05 for all). Thus, OIA rabbits mimicked early-stage RA at 6 to 8 weeks, middle-stage RA at 8 to 12 weeks and late-stage RA at 12 to 16 weeks. Power Doppler image grade, CEUS grade and peak intensity, especially when combined with CD31 expression data, accurately characterized the extent of synovial vascularization in a rabbit model of RA. Increased vascularity based on CEUS may have value for the early diagnosis of RA.

Autophagy Activation by Resveratrol Reduces Severity of Experimental Rheumatoid Arthritis.

SCOPE: Previous work reported that dietary supplementation with resveratrol lowers synovial hyperplasia, inflammatory and oxidative damage in an antigen-induced arthritis (AIA) model. Here, it is investigated whether resveratrol can regulate the abnormal synovial proliferation by inducing autophagy and controlling the associated inflammatory response. METHODS AND RESULTS: Animals treated with resveratrol 8 weeks before AIA induction show the highest significant signal for microtubule-associated protein 1 light chain 3 by confocal microscopy. Besides, resveratrol significantly reduces p62 expression, but it does not increase the signal of beclin-1. Also, active caspase-3 expression, as well as poly(ADP-ribose) polymerase, is upregulated in the AIA group, and is significantly reduced in resveratrol-treated AIA group. Resveratrol also mitigates angiopoietin-1 and vascular endothelial growth factor signals. Finally, resveratrol significantly reduces the serum levels of IL-1ß, C reactive protein, and prostaglandin E2, as well as nuclear factor κB synovial tissue expression, which shows a significant correlation with p62 expression. CONCLUSION: Dietary supplementation with resveratrol induces the noncanonical autophagy pathway and limits the cross-talk with inflammation, which in consequence modulates the synovial hyperplasia. Preventive strategies that incorporate dietary intervention with resveratrol may offer a potential therapeutic alternative to drugs to influence the risk of rheumatoid arthritis and influence its course.

Implication of the deacetylase sirtuin-1 on synovial angiogenesis and persistence of experimental arthritis.

OBJECTIVES: To decipher the phenotype of endothelial cells (ECs) derived from circulating progenitors issued from patients with rheumatoid arthritis (RA). METHODS: RA and control ECs were compared according to their proliferative capacities, apoptotic profile, response to tumour necrosis factor (TNF)-α stimulation and angiogenic properties. Microarray experiments were performed to identify gene candidates relevant to pathological angiogenesis. Identified candidates were detected by RT-PCR and western blot analysis in ECs and by immunohistochemistry in the synovium. Their functional relevance was then evaluated in vitro after gene invalidation by small interfering RNA and adenoviral gene overexpression, and in vivo in the mouse model of methyl-bovine serum albumin-(mBSA)-induced arthritis. RESULTS: RA ECs displayed higher proliferation rate, greater sensitisation to TNF-α and enhanced in vitro and in vivo angiogenic capacities. Microarray analyses identified the NAD-dependent protein deacetylase sirtuin-1 (SIRT1) as a relevant gene candidate. Decreased SIRT1 expression was detected in RA ECs and synovial vessels. Deficient endothelial SIRT1 expression promoted a proliferative, proapoptotic and activated state of ECs through the acetylation of p53 and p65, and lead the development of proangiogenic capacities through the upregulation of the matricellular protein cysteine-rich angiogenic protein-61. Conditional deletion of SIRT1 in ECs delayed the resolution of experimental methyl-bovine serum albumin-(mBSA)-induced arthritis. Conversely, SIRT1 activation reversed the pathological phenotype of RA ECs and alleviates signs of experimental mBSA-induced arthritis. CONCLUSIONS: These results support a role of SIRT1 in RA and may have therapeutic implications, since targeting angiogenesis, and especially SIRT1, might be used as a complementary therapeutic approach in RA.

Enhanced angiogenic function in response to fibroblasts from psoriatic arthritis synovium compared to rheumatoid arthritis.

INTRODUCTION: Angiogenesis is an early event in the pathogenesis of both psoriatic arthritis (PsA) and rheumatoid arthritis (RA); however, there are striking differences in blood vessel morphology and activation between the two arthropathies. The aim of this study was to assess if the PsA and RA joint microenvironments differentially regulate endothelial cell function. METHODS: PsA and RA primary synovial fibroblasts (SFC) were isolated from synovial biopsies, grown to confluence, and supernatants harvested and termed 'conditioned media' (CM). Human umbilical vein endothelial cells (HUVEC) were cultured with PsA SFC or RA SFC-CM (20%). HUVEC tube formation, migration, and PBMC adhesion were assessed by matrigel tube formation, wound repair, and PBMC adhesion assays. HUVEC cell surface expression of ICAM, VCAM, and E-Selectin was assessed by flow cytometry. Transcriptome analysis of genes promoting angiogenesis was performed by real-time PCR. Finally, a MSD multiplex angiogenic assay was performed on PsA SFC and RA SFC supernatants. RESULTS: Macroscopic synovitis and vascularity were similar in PsA and RA patients; however, significant differences in vascular morphological pattern were recorded with tortuous, elongated vessels observed in PsA compared to straight regular branching vessels observed in RA. Transcriptome analysis showed strong upregulation of the pro-angiogenic signature in HUVEC primed with PsA SFC-CM compared to RA SFC-CM and basal control. In parallel, paired PsA SFC-CM significantly induced HUVEC tube formation compared to that of RA SFC-CM. Furthermore, PsA SFC-CM induced HUVEC migration was paralleled by a significant induction in VEGFA, PFKFB3, ICAM-1, and MMP3 mRNA expression. A significant increase in PBMC adhesion and cell surface expression of VCAM-1, ICAM-1, and E-Selectin expression was also demonstrated in PsA SFC-CM-primed HUVEC compared to RA SFC-CM. Finally, VEGF, TSLP, Flt-1, and Tie-2 expression was elevated in PsA SFC-CM compared to RA SFC-CM, with no significant difference in other pro-angiogenic mediators including MIP-3, bFGF, PIGF, and MCP-1. CONCLUSION: PsA SFC and RA SFC secreted factors differentially regulate endothelial cell function, with soluble mediators in the PsA joint microenvironment inducing a more pro-angiogenic phenotype compared to the RA.

Phosphoinositide-3 kinase gamma regulates caspase-1 activation and leukocyte recruitment in acute murine gout.

This study investigates the participation of PI3Kγ in the development of joint inflammation and dysfunction in an experimental model of acute gout in mice. Acute gout was induced by injection of monosodium urate (MSU) crystals into the tibiofemoral joint of mice. The involvement of PI3Kγ was evaluated using a selective inhibitor and mice deficient for PI3Kγ (PI3Kγ-/- ) or with loss of kinase activity. Neutrophils recovered from the inflamed joint were quantified and stained for phosphorylated Akt (pAkt) and production of reactive oxygen species (ROS). The adherence of leukocytes to the joint microvasculature was assessed by intravital microscopy and cleaved caspase-1 by Western blot. Injection of MSU crystals induced massive accumulation of neutrophils expressing phosphorylated Akt. In the absence of PI3Kγ, there was reduction of pAkt expression, chemokine production, and neutrophil recruitment. Genetic or pharmacological inhibition of PI3Kγ reduced the adherence of leukocytes to the joint microvasculature, even in joints with established inflammation. Neutrophils from PI3Kγ-/- mice produced less ROS than wild-type neutrophils. There was decreased joint damage and dysfunction in the absence of PI3Kγ. In addition, in the absence of PI3Kγ activity, there was reduction of cleaved caspase-1 and IL-1ß production in synovial tissue after injection of MSU crystals and leukotriene B4 . Our studies suggest that PI3Kγ is crucial for MSU crystal-induced acute joint inflammation. It is necessary for regulating caspase-1 activation and for mediating neutrophil migration and activation. Drugs that impair PI3Kγ function may be useful to control acute gout inflammation.

Mechanisms of vascular permeability and remodeling associated with hemarthrosis in factor VIII-deficient mice.

BACKGROUND: Vascular remodeling associated with hemophilic arthropathy (HA) may contribute to bleed propagation, but the mechanisms remain poorly understood. OBJECTIVES: To explore molecular mechanisms of HA and the effects of hemostasis correction on synovial vascular remodeling after joint injury in hypocoagulable mice. METHODS: Factor VIII (FVIII)-deficient mice +/- FVIII treatment and hypocoagulable wild-type mice (Hypo BALB/c) were subjected to subpatellar puncture. Hypo BALB/c mice were treated with warfarin and anti-FVIII before injury, after which warfarin was continued for 2 weeks or reversed +/- continuous anti-FVIII until harvest. Synovial vascularity was analyzed at baseline and 2 to 4 weeks post injury by histology, musculoskeletal ultrasound with power Doppler (microvascular flow), and Evans blue extravasation (vascular permeability). Synovial gene expression and systemic markers of vascular collagen turnover were studied in FVIII-deficient mice by RNA sequencing and enzyme-linked immunosorbent assay. RESULTS: Vascular changes occurred in FVIII-deficient and Hypo BALB/c mice after injury with minimal effect of hemostasis correction. Increased vascular permeability was only significant in FVIII-deficient mice, who exhibited more pronounced vascular remodeling than Hypo BALB/c mice despite similar bleed volumes. FVIII-deficient mice exhibited a strong transcriptional response in synovium that was only partially affected by FVIII treatment and involved genes relating to angiogenesis and extracellular matrix remodeling, with vascular collagen turnover markers detected systemically. CONCLUSIONS: Intact hemostasis at the time of hemarthrosis and during healing are both critical to prevent vascular remodeling, which appears worse with severe and prolonged FVIII deficiency. Unbiased RNA sequencing revealed potential targets for intervention and biomarker development to improve management of HA.

[Effect of Fengshi Qutong Capsules on synovial angiogenesis in rats with type â ¡ collagen induced arthritis].

To observe the effect of Fengshi Qutong Capsules(FSQTC) on angiogenesis of rat aortarings and in knee joint synovium of type Ⅱ collagen-induced arthritis(CIA) rats. The blood vessel of aorta rings of normal SD rats were induced by vascular endothelial growth factor(VEGF) 20 µg·L~(-1 )in vitro, and were treated with FSQTC(0.02, 0.1 and 0.5 µg·L~(-1)) continuously for 9 days. The number, length and area of neovascularization of the vascular ring were measured. SD rats were immunized to establish collagen-induced arthritis. CIA rats were treated with FSQTC(0.25, 0.5, 1 g·kg~(-1)·d~(-1)) and methotrexate(0.2 mg·kg~(-1)·d~(-1)) daily for 19 days. Histopathological examination(HE) was performed to observe the vascular morphology and vascular density in the synovial membrane of the inflamed joint. Immunohistochemistry was performed to observe the expression of platelets-endothelial cell adhesion molecule(CD31), VEGF and VEGF receptor 2(VEGFR_2)in the synovium. Immunofluorescence was performed to observe the expression of CD31 and α smooth muscle actin(αSMA) in synovial membrane.TGF-ß, PDGF and VEGFR_2 in serum were detected by enzyme-linked immunosorbent assay. The number, branch length and area of blood vessels of aorta rings were significantly increased induced by VEGF, and FSQTC could significantly reduce the number, branch length and area of blood vessels. Compared with the normal group, the vascular density, CD31 positive expression, CD31~+/αSMA~- immature and total vascular positive expression in the synovial membrane of the model group were significantly increased, and so as VEGF and VEGFR_2 in the synovium. The VEGFR_2, TGF-ß and PDGF in sera were also significantly increased in model group. FSQTC reduced the synovial vascular density and inhibited the positive expression of CD31, CD31~+/αSMA~- immature blood vessels and total vascular. FSQTC has no significant effect on CD31~+/αSMA~+mature blood vessels. FSQTC also negatively inhibited the expression of VEGF, VEGFR_2, TGF-ß and PDGF in synovial membrane and/or sera. The effect of methotrexate is similar with to the high dose group. Our results demonstrated that FSQTC could inhibit the angiogenesis of synovial tissue in CIA rats and of aortaring in rats, which is related to the reduction of angiogenesis regulatory factor.

Vascular endothelial growth factor signaling in VE-cadherin expression and tube-like formation by rheumatoid arthritic synovial fibroblast-like cells.

An increase in the vasculature is one of most representative changes in the synovial tissue of joints in rheumatoid arthritis (RA) and is closely associated with disease progression. Although the vasculatures are believed to be a result of VE-cadherin-dependent angiogenesis and a possible therapeutic target of the disease, synovial fibroblastic cells express VE-cadherin and form tube-like structures, suggesting that vasculatures in RA synovium may not simply result from angiogenesis. This paper analyzes a mechanism of VE-cadherin expression by rheumatoid arthritic synovial fibroblast-like cells (RSFLs) and their involvement in the tube-like formation. A representative angiogenic factor, vascular endothelial growth factor (VEGF), and its binding to a predominant receptor (VEGFR2) activated VE-cadherin expression and the signaling pathways of ERK/MAPK and PI3K/AKT/mTOR. Treatment of RSFLs with signaling pathway inhibitors, VEGFR2 siRNA and a VEGF-antagonizing mimicking peptide inhibited VE-cadherin expression dose-dependently. VEGF-stimulated tube-like formation by RSFLs on Matrigel was hindered by the mimicking peptide and inhibitor treatment. This data demonstrates that RSFLs activated by VEGF binding of VEGFR2 express VE-cadherin and formed tube-like structure under the control of ERK/MAPK and PI3K/AKT/mTOR pathways suggesting that the inhibition suppresses vascular development in RA synovium.

Altered metabolic pathways regulate synovial inflammation in rheumatoid arthritis.

Rheumatoid arthritis is characterized by synovial proliferation, neovascularization and leucocyte extravasation leading to joint destruction and functional disability. The blood vessels in the inflamed synovium are highly dysregulated, resulting in poor delivery of oxygen; this, along with the increased metabolic demand of infiltrating immune cells and inflamed resident cells, results in the lack of key nutrients at the site of inflammation. In these adverse conditions synovial cells must adapt to generate sufficient energy to support their proliferation and activation status, and thus switch their cell metabolism from a resting regulatory state to a highly metabolically active state. This alters redox-sensitive signalling pathways and also results in the accumulation of metabolic intermediates which, in turn, can act as signalling molecules that further exacerbate the inflammatory response. The RA synovium is a multi-cellular tissue, and while many cell types interact to promote the inflammatory response, their metabolic requirements differ. Thus, understanding the complex interplay between hypoxia-induced signalling pathways, metabolic pathways and the inflammatory response will provide better insight into the underlying mechanisms of disease pathogenesis.

Resveratrol Alleviates Rheumatoid Arthritis via Reducing ROS and Inflammation, Inhibiting MAPK Signaling Pathways, and Suppressing Angiogenesis.

Rheumatoid arthritis (RA) is a systemic autoimmune disease primarily affecting joints and is featured by chronic synovial inflammation and angiogenesis. We employed a bovine type-II collagen (BIIC)-induced Sprague-Dawley rat arthritis model and an in vitro RA model based on interleukin (IL)-1ß-stimulated rat synovial cells (RSC-364) to explore the preventive effect of resveratrol on RA and the underlying mechanisms. We found that resveratrol ameliorated BIIC-elicited synovitis and RA-related pathological hallmarks such as inflammatory cell infiltration and angiogenesis in the synovial tissue. Also, BIIC-stimulated rats displayed increased serum levels of proinflammatory cytokines and reactive oxygen species (ROS), as manifested by elevated serum malonaldehyde contents combined with reduced superoxide dismutase activity. It is noteworthy that resveratrol abolished BIIC-induced ROS and inflammation, confirming the antioxidative and anti-inflammatory actions of resveratrol in the context of RA. Furthermore, immunoblotting indicated that resveratrol downregulated the increase in the levels of hypoxia-inducible factor-1α (HIF-1α) and that of the activated phosphorylation of p38 mitogen-activated protein kinase (MAPK) and c-Jun N-terminal kinase in IL-1ß-stimulated RSC-364 cells. Moreover, we observed that resveratrol-treated RSC-364 cells displayed both G0/G1 cell-cycle arrest and enhanced levels of apoptosis. Altogether, the present evidence established the preventive role of resveratrol in RA progression. Mechanistically, resveratrol inhibits MAPK signaling pathways, likely by reducing ROS accumulation, to suppress the inflammatory response and cell proliferation and to provoke cell apoptosis in the synovial tissue, along with mitigation of HIF-1α-mediated angiogenesis. Thus resveratrol appears to hold great potential for clinical translation as a novel RA therapeutic.

Morin Exerts Anti-Arthritic Effects by Attenuating Synovial Angiogenesis via Activation of Peroxisome Proliferator Activated Receptor-γ.

SCOPE: Morin, a flavonoid occurring in many dietary plants, can reduce the number of synovial blood vessels and ameliorate collagen-induced arthritis (CIA) in rats. Herein, its underlying mechanisms in view of the peroxisome proliferator activated receptor-γ (PPARγ) pathway are addressed. METHODS AND RESULTS: In vitro, wound-healing and transwell assays are conducted to explore the effect of morin on HUVECs migration. Morin inhibits HUVECs migration and tube formation induced by VEGF, which is reversed by PPARγ antagonist GW9662 or siPPARγ. Molecular docking and competitive binding assays show that morin could bind to PPARγ. Morin increases the expression of PDK4 and CD36 in a PPARγ-dependent manner and increases the luciferase activity in cells transfected with PPARγ plasmid, which indicates that morin could activate PPARγ after binding. In addition, morin increases the expression of PTEN, a target gene of PPARγ that suppresses angiogenesis and inhibits PI3K/Akt signaling. The effects of morin on the PTEN-PI3K/Akt pathway are diminished by GW9662 and siPPARγ. In vivo studies show that morin ameliorates rat CIA, reduces synovial angiogenesis, and upregulates the expression of PTEN in the synovium, which is almost completely abolished by GW9662. CONCLUSIONS: Morin is a potential agonist of PPARγ, which attenuates synovial angiogenesis and arthritis via the PPARγ-PTEN-PI3K/Akt pathway.

Infrapatellar fat pad features in osteoarthritis: a histopathological and molecular study.

Objective: The infrapatellar fat pad (IFP) is considered a local producer of adipocytokines, suggesting a potential role in OA. The objective of this study was to evaluate the histopathological and molecular characteristics of OA IFPs compared with controls. Methods: The histopathological characteristics of IFPs were evaluated in patients undergoing total knee replacements and in control patients (without OA), considering the following parameters: presence of inflammatory cells, vascularization, adipose lobules dimension and thickness of the interlobular septa. Immunohistochemistry was performed to evaluate VEGF, monocyte chemotactic protein 1 (MCP-1) and IL-6 proteins. Quantitative real time PCR was performed to evaluate the expression levels of adipocytokines in the OA IFPs. Results: OA IFPs showed an increase in inflammatory infiltration, vascularization and thickness of the interlobular septa compared with controls. VEGF, MCP-1 and IL-6 proteins were higher in OA IFPs compared with in controls. Inflammatory infiltration, hyperplasia, vascularization and fibrosis were increased in OA IFP synovial membranes compared with in those of controls. VEGF protein levels were associated with an increased number of vessels in the OA IFPs, while MCP-1 and IL-6 protein levels were associated with higher grades of inflammatory infiltration. Leptin levels were positively correlated with adiponectin and MCP-1expression, while adiponectin positively correlated with peroxisome proliferative activated receptor gamma, MCP-1 and IFP vascularity. MCP-1 showed a positive correlation with peroxisome proliferative activated receptor gamma. IFP lobules dimensions were positively correlated with IL-6 expression and negatively with thickness of interlobular septa. VEGF mRNA levels were positively correlated with increased synovial vascularity. Conclusions: OA IFPs and synovial membranes are more inflamed, vascularized and fibrous compared with those of control patients (without OA).

Targeting synovial neoangiogenesis in rheumatoid arthritis.

In Rheumatoid arthritis (RA), neoangiogenesis is an early and crucial event to promote the development of the hyperplasic proliferative pathologic synovium. Endothelial cells are critical for the formation of new blood vessels since they highly contribute to angiogenesis and vasculogenesis. Current therapies in RA target the inflammatory consequences of autoimmune activation and despite major improvements these last years still refractory patients or incomplete responders may be seen raising the point of the need to identify complementary additive and innovative therapies. This review resumes the mechanisms of synovial neoangiogenesis in RA, including recent insights on the implication of vasculogenesis, and the regulation of synovial neoangiogenesis by angiogenic and inflammatory mediators. In line with the recent development of vascular-targeted therapies used in cancer and beyond, we also discuss possible therapeutic implications in RA, in particular the combination of targeted immunotherapies with anti-angiogenic molecules.

Differential effects of IL-6 blockade tocilizumab and TNF inhibitors on angiogenesis in synovial tissues from patients with rheumatoid arthritis.

OBJECTIVE: To compare the influences of tocilizumab (TCZ) and TNF inhibitors (TNFi) on the angiogenesis in synovial tissues of rheumatoid arthritis (RA). METHODS: Synovial tissues were obtained during joint operations from 13 RA patients treated with TCZ for at least 4 months with or without previous use of TNFi, from 13 RA patients with TNFi alone and from 10 RA patients with only conventional synthetic DMARDs (csDMARDs). Synovial tissues were evaluated by hematoxylin and eosin stain as well as by immunohistological staining with anti-CD31 in which the microvessel densities (MVD) were quantitated. Synovial histopathology was scored for various components. RESULTS: The most remarkable change in the synovium with TCZ was reduced angiogenesis as well as degeneration of lining layers irrespective of the previous use of TNFi. Thus, MVD in patients treated with TCZ with or without previous TNFi were significantly decreased compared with those in patients with TNFi alone or with csDMARDs. Moreover, MVD was significantly correlated with lining layer proliferation, but not with synovial stromal proliferation or inflammatory changes. CONCLUSIONS: These results demonstrated that inhibition of angiogenesis is a unique action of TCZ. Moreover, the data also suggest that lining layers proliferation might be closely associated with angiogenesis.

Number and distribution of nutrient foramina within the femoral neck and their relationship to the retinacula of Weitbrecht: an anatomical study.

Precise knowledge of the vascular supply of the femoral head is critical when contemplating surgery around the femoral head and neck junction. To determine the blood supply to the femoral neck, 2417 nutrient foramina from 76 cadaveric specimens were analyzed based on size, number, and distribution. Within the subcapital, transcervical, and basicervical regions of the femoral neck, the largest numbers of nutrient foramina were found on the superior (lateral) surface, followed by the anterior and posterior surfaces, and then the inferior (medial) surface (all p < 0.001). The diameters of most of the nutrient foramina were less than 1 mm. For the posterior and superior surfaces, the nutrient foramina in the basicervical region were significantly larger than those within the transcervical or subcapital regions (nutrient foramina >2 mm posteriorly: 23.6, 12.7, and 9.0 % in the basicervical, transcervical, and subcapital regions, respectively; superiorly: 23.7 vs. 15.4 vs. 16.8 %, respectively). In conclusion, neither the anterior nor the inferior surfaces in the basicervical, transcervical, and subcapital regions showed any significant differences in nutrient foraminal size. The areas containing densely distributed nutrient foramina were consistent with the regions covered by the retinacula of Weitbrecht.

Decrease in articular hypoxia and synovial blood flow at early time points following infliximab and etanercept treatment in rheumatoid arthritis.

OBJECTIVES: An important feature of rheumatoid arthritis (RA) is hypoxia-driven synovial angiogenesis, but the relationship between change in vascularity, as measured by power Doppler ultrasound (PDUS), and oxygen tensions is unaddressed. METHODS: Metacarpophalangeal (MCP) joint PDUS was assessed in 23 patients with RA, alongside arthroscopic synovitis and oxygen tension measurements, at baseline and 4 weeks after anti-tumour necrosis factor (TNF) inhibitors. RESULTS: Anti-TNF reduced PDUS scores, which were negatively correlated with rise in oxygen tensions. The latter was related to good EULAR response at week 52. CONCLUSIONS: Anti-TNF results in rapid reduction in synovial blood flow, with a corresponding rise in oxygen tension most marked in EULAR good responders.