Starving the synovium: angiogenesis and inflammation in rheumatoid arthritis

Systematic Review: Targeted Molecular Imaging of Angiogenesis and Its Mediators in Rheumatoid Arthritis

Extensive angiogenesis is a characteristic feature in the synovial tissue of rheumatoid arthritis (RA) from a very early stage of the disease onward and constitutes a crucial event for the development of the proliferative synovium. This process is markedly intensified in patients with prolonged disease duration, high disease activity, disease severity, and significant inflammatory cell infiltration. Angiogenesis is therefore an interesting target for the development of new therapeutic approaches as well as disease monitoring strategies in RA. To this end, nuclear imaging modalities represent valuable non-invasive tools that can selectively target molecular markers of angiogenesis and accurately and quantitatively track molecular changes in multiple joints simultaneously. This systematic review summarizes the imaging markers used for single photon emission computed tomography (SPECT) and/or positron emission tomography (PET) approaches, targeting pathways and mediators involved in synovial neo-angiogenesis in RA.

Role of mesenteric component in Crohn’s disease: A friend or foe?

Crohn’s disease (CD) is a complex and relapsing gastrointestinal disease with mesenteric alterations. The mesenteric neural, vascular, and endocrine systems actively take part in the gut dysbiosis-adaptive immunity-mesentery-body axis, and this axis has been proven to be bidirectional. The abnormalities of morphology and function of the mesenteric component are associated with intestinal inflammation and disease progress of CD via responses to afferent signals, neuropeptides, lymphatic drainage, adipokines, and functional cytokines. The hypertrophy of mesenteric adipose tissue plays important roles in the pathogenesis of CD by secreting large amounts of adipokines and representing a rich source of proinflammatory or profibrotic cytokines. The vascular alteration, including angiogenesis and lymphangiogenesis, is concomitant in the disease course of CD. Of note, the enlarged and obstructed lymphatic vessels, which have been described in CD patients, are likely related to the early onset submucosa edema and being a cause of CD. The function of mesenteric lymphatics is influenced by endocrine of mesenteric nerves and adipocytes. Meanwhile, the structure of the mesenteric lymphatic vessels in hypertrophic mesenteric adipose tissue is mispatterned and ruptured, which can lead to lymph leakage. Leaky lymph factors can in turn stimulate adipose tissue to proliferate and effectively elicit an immune response. The identification of the role of mesentery and the crosstalk between mesenteric tissues in intestinal inflammation may shed light on understanding the underlying mechanism of CD and help explore new therapeutic targets.

CYT387 Inhibits the Hyperproliferative Potential of Fibroblast-like Synoviocytes via Modulation of IL-6/JAK1/STAT3 Signaling in Rheumatoid Arthritis

Fibroblast-like synoviocytes (FLS) are the critical effector cells primarily involved in rheumatoid arthritis (RA) disease pathogenesis. Interleukin (IL)-6, a proinflammatory cytokine most abundantly expressed in the rheumatoid synovium, promotes Janus kinase (JAK)/signal transducer and transcriptional activator (STAT) signaling cascade activation in RA-FLS, thus leading to its aggressive phenotype, invasiveness, and joint destruction. Momelotinib (CYT387) is a selective small-molecule inhibitor of JAK1/2 and is clinically approved to treat myelofibrosis. However, the therapeutic efficacy of CYT387 in FLS mediated RA pathogenesis is less known. In the present study, we investigated the modulatory effect of CYT387 on IL6/JAK/STAT signaling cascade in FLS induced RA pathogenesis. CYT387 treatment inhibited IL-6 induced high proliferative and migratory potential of FLS cells isolated from adjuvant-induced arthritic (AA) rats. CYT387 reduced the expression of PRMT5, survivin, and HIF-1α mediated by IL-6/sIL-6R in AA-FLS in a dose-dependent manner. The IL-6/sIL-6R induced expression of angiogenic factors such as VEGF and PIGF in AA-FLS cells was found downregulated by CYT387 treatment. Importantly, CYT387 significantly reduced IL-6/sIL-6R dependent activation of JAK1 and STAT3 and increased SOCS3 expression in AA-FLS cells. Next, the S3I-201 mediated blockade of STAT3 activation supported the inhibitory effect of CYT387 on IL-6/JAK1/STAT3 signaling cascade in AA-FLS. Overall, this study proves that CYT387 inhibits proliferation, migration, and pathogenic disease potential of FLS isolated from adjuvant-induced arthritic (AA) rats via targeting IL-6/JAK1/STAT3 signaling cascade.

Liposomal Nanosystems in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an autoimmune disease that affects the joints and results in reduced patient quality of life due to its chronic nature and several comorbidities. RA is also associated with a high socioeconomic burden. Currently, several available therapies minimize symptoms and prevent disease progression. However, more effective treatments are needed due to current therapies' severe side-effects, especially under long-term use. Drug delivery systems have demonstrated their clinical importance-with several nanocarriers present in the market-due to their capacity to improve therapeutic drug index, for instance, by enabling passive or active targeting. The first to achieve market authorization were liposomes that still represent a considerable part of approved delivery systems. In this manuscript, we review the role of liposomes in RA treatment, address preclinical studies and clinical trials, and discuss factors that could hamper a successful clinical translation. We also suggest some alterations that could potentially improve their progression to the market.

Anti-angiogenic effect of Shikonin in rheumatoid arthritis by downregulating PI3K/AKT and MAPKs signaling pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Zicao is the dried root of Lithospermum erythrorhizon Sieb, et Zucc, Arnebia euchroma (Royle) Johnst, or Arnebia guttata Bunge and commonly used to treat viral infection, inflammation, arthritis and cancer in China.Shikonin (SKN) is a major active chemical component isolated from zicao. Previous research showed that SKN has anti-inflammatory, immunomodulatory and analgesic effects, and inhibits the development of arthritis and the condition of collagen arthritis (CIA) mice; nevertheless, its role in the angiogenesis of rheumatoid arthritis (RA) has not been elucidated.

AIM OF THE STUDY

The purpose of this study was to investigate the antiangiogenic activity of SKN in CIA rats and various angiogenesis models.

MATERIAL AND METHODS

The anti-arthritic effect of SKN on CIA rats was tested by arthritis score, arthritis incidence, radiological observation and histopathology evaluation of inflamed joints. Vessel density evaluated with CD31 immunohistochemistry/immunofluorescence in joint synovial membrane tissues of CIA rats, chick chorioallantoic membrane assay, rat aortic ring assay, and the migration, invasion, adhesion and tube formation of human umbilical vein endothelial (HUVEC) cells induced by tumor necrosis factor (TNF)-α were used to measured the antiangiogenenic activity of SKN. Moreover, the effect of SKN on the expression of angiogenic mediators, such as vascular endothelial growth factor (VEGF), VEGFR2, TNF-α, interleukin (IL)-1β, platelet derived growth factor (PDGF) and transforming growth factor (TGF)-β in sera and joint synovia of rats, and in TNF-α-induced MH7A/HUVEC cells were measured by immunohistochemistry, enzyme linked immunosorbent assay, Western blot and/or real-time polymerase chain reaction (PCR). Through the analysis of protein and mRNA levels of phosphoinositide 3-kinase (PI3K), Akt and PTEN, and the autophosphorylation of ERK1/2, JNK and p38 in joint synovia of rats and in TNF-α-induced HUVEC cells, the molecular mechanism of its inhibition was elucidated by using Western blot and/or real-time PCR.

RESULTS

SKN significantly reduced the arthritis score and arthritis incidence, and inhibited inflammation, pannus formation, cartilage and bone destruction of inflamed joints in CIA rats. Partially, SKN remarkably decreased the immature blood vessels in synovial membrane tissues of inflamed joints from CIA rats. It also suppressed in vivo angiogenesis in chick embryo and VEGF₁₆₅-induced microvessel sprout formation ex vivo. Meanwhile, SKN inhibited TNF-α-induced migration, invasion, adhesion and tube formation of HUVEC cells. Moreover, SKN significantly decreased the expression of angiogenic activators including VEGF, VEGFR2, TNF-α, IL-1β, PDGF and TGF-β in synovia of CIA rats and/or in MH7A/HUVEC cells. More interestingly, SKN downregulated PI3K and Akt, and simultaneously upregulated PTEN both at protein and mRNA levels in synovia tissues and/or in TNF-α-induced HUVEC cells. It also suppressed the phosphorylation and gene level of TNF-α-induced signaling molecules, as ERK1/2, JNK, and p38 in synovium and/or in TNF-α-induced HUVEC cells.

CONCLUSION

These findings indicate for the first time that SKN has the anti-angiogenic effect in RA in vivo, ex vivo and in vitro by interrupting the PI3K/AKT and MAPKs signaling pathways.

Evaluation of Femoral Head Perfusion by Contrast-Enhanced Ultrasound in a Rabbit Model of Steroid-Induced Osteonecrosis

OBJECTIVES

To study the technical feasibility of contrast-enhanced ultrasound (CEUS) in evaluating femoral head perfusion in a rabbit model of steroid-induced femoral head osteonecrosis.

METHODS

Twenty rabbits were divided randomly into a control group (n = 8) and an experimental group (n = 12). Rabbits in the experimental group were induced by lipopolysaccharide and methylprednisolone to build a model of steroid-induced femoral head osteonecrosis. Contrast-enhanced ultrasound examinations were performed at 3 and 5 weeks after induction. Then, pathologic examinations and microvessel density (MVD) calculations were performed on the excised rabbit femoral heads.

RESULTS

The MVD of the experimental group decreased significantly 3 and 5 weeks after induction compared with that of the control group. According to the CEUS examination results, significant differences existed in the ascending slope, descending slope, mean transit time, and time to peak between the groups at 5 weeks (P < .05). A correlation analysis showed that the descending slope had a certain correlation with the MVD (correlation coefficient, 0.376). A receiver operating characteristic curve was used to analyze the capacity of the CEUS parameters to predict the occurrence of osteonecrosis. The areas under the curve for the ascending slope and descending slope were 0.758 and 0.760, respectively (P < .05).

CONCLUSIONS

Contrast-enhanced ultrasound can visualize the microcirculation in steroid-induced osteonecrosis of the femoral head in rabbits and may be a useful imaging method for the early monitoring and prediction of femoral head osteonecrosis.

Nanomedicines for the delivery of glucocorticoids and nucleic acids as potential alternatives in the treatment of rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease that affects 0.5-1% of the world population. Current treatments include on one hand non-steroidal anti-inflammatory drugs and glucocorticoids (GCs) for treating pain and on the other hand disease-modifying anti-rheumatic drugs such as methotrexate, Janus kinase inhibitors or biologics such as antibodies targeting mainly cytokine expression. More recently, nucleic acids such as siRNA, miRNA, or anti-miRNA have shown strong potentialities for the treatment of RA. This review discusses the way nanomedicines can target GCs and nucleic acids to inflammatory sites, increase drug penetration within inflammatory cells, achieve better subcellular distribution and finally protect drugs against degradation. For GCs such a targeting effect would allow the treatment to be more effective at lower doses and to reduce the administration frequency as well as to induce much fewer side-effects. In the case of nucleic acids, particularly siRNA, knocking down proteins involved in RA, could importantly be facilitated using nanomedicines. Finally, the combination of both siRNA and GCs in the same carrier allowed for the same cell to target both the GCs receptor as well as any other signaling pathway involved in RA. Nanomedicines appear to be very promising for the delivery of conventional and novel drugs in RA therapeutics. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Biology-Inspired Nanomaterials > Nucleic Acid-Based Structures.

A Combined Transcriptomic and Genomic Analysis Identifies a Gene Signature Associated With the Response to Anti-TNF Therapy in Rheumatoid Arthritis

Background: Rheumatoid arthritis (RA) is the most frequent autoimmune disease involving the joints. Although anti-TNF therapies have proven effective in the management of RA, approximately one third of patients do not show a significant clinical response. The objective of this study was to identify new genetic variation associated with the clinical response to anti-TNF therapy in RA.

Methods: We performed a sequential multi-omic analysis integrating different sources of molecular information. First, we extracted the RNA from synovial biopsies of 11 RA patients starting anti-TNF therapy to identify gene coexpression modules (GCMs) in the RA synovium. Second, we analyzed the transcriptomic association between each GCM and the clinical response to anti-TNF therapy. The clinical response was determined at week 14 using the EULAR criteria. Third, we analyzed the association between the GCMs and anti-TNF response at the genetic level. For this objective, we used genome-wide data from a cohort of 348 anti-TNF treated patients from Spain. The GCMs that were significantly associated with the anti-TNF response were then tested for validation in an independent cohort of 2,706 anti-TNF treated patients. Finally, the functional implication of the validated GCMs was evaluated via pathway and cell type epigenetic enrichment analyses.

Results: A total of 149 GCMs were identified in the RA synovium. From these, 13 GCMs were found to be significantly associated with anti-TNF response (P < 0.05). At the genetic level, we detected two of the 13 GCMs to be significantly associated with the response to adalimumab (P = 0.0015) and infliximab (P = 0.021) in the Spain cohort. Using the independent cohort of RA patients, we replicated the association of the GCM associated with the response to adalimumab (P = 0.0019). The validated module was found to be significantly enriched for genes involved in the nucleotide metabolism (P = 2.41e-5) and epigenetic marks from immune cells, including CD4+ regulatory T cells (P = 0.041).

Conclusions: These findings show the existence of a drug-specific genetic basis for anti-TNF response, thereby supporting treatment stratification in the search for response biomarkers in RA.

Hydroalcoholic extract of Brazilian green propolis modulates inflammatory process in mice submitted to a low protein diet

The occurrence of inflammation and protein malnutrition is an aggravating risk factor for morbidity and mortality in the clinical setting. The green propolis, a natural product made by Apis mellifera bees from Baccharis dracunculifolia resin, has therapeutic potential to modulate chronic inflammation. However, its effect on inflammation in an impaired nutritional status is not known. The aim of this study was to characterize the effects of the administration of the hydroalcoholic extract of the green propolis in the chronic inflammatory process of mice submitted to a low-protein diet. For this, we used the subcutaneous implantation of sponge disks as an inflammatory model and the animals were distributed in the following groups: standard protein diet (12% protein content), control treatment; standard protein diet, propolis treatment; low-protein diet (3% protein content), control treatment; low-protein diet, propolis treatment. Propolis was given daily at a dose of 500 mg/kg (p.o.) during a period of 7 or 15 days. Our main findings show that animals fed with standard protein diet and treated with propolis had low levels of red blood cells, hemoglobin, and hematocrit, with the subsequent reestablishment of these levels, in addition to monocyte count elevation and higher TNF levels after one week of treatment. In the low-protein diet group, the propolis treatment provided a significant recovery in weight and maintenance of total serum protein levels at the end of two weeks of treatment. Histological analysis showed propolis reduced the inflammatory infiltrate in the sponges of both standard and low-protein diet groups. In addition, the propolis extract presented antiangiogenic effect in both groups. Therefore, our data suggests that the hydroalcoholic extract of the green propolis promotes weight recovery and avoid the reduction of protein levels, in addition to inhibit inflammation and angiogenesis in animals fed with a low-protein diet.

Linking systemic angiogenic markers to synovial vascularization in rheumatoid arthritis

Background

Neoangiogenesis is a crucial event to promote the development of the hyperplasic proliferative pathologic synovium in Rheumatoid arthritis (RA). Ultrasound (US) is sensitive for detection of power Doppler (PD) vascularization.

Objective

To explore the associations between a set of complementary circulating angiogenic markers and a comprehensive US assessment in patients with RA.

Patients and methods

Serum levels of eight angiogenic markers were measured by quantitative ELISAs in a total of 125 patients with RA, who were all systematically assessed in parallel by PDUS, performed on 32 joints.

Results

Serum levels of soluble Vascular Cell Adhesion Molecule-1 (sVCAM-1) and Tie-2 were more likely to be increased in patients with synovial hyperemia detected on at least one joint (Power Doppler grade ≥1). sVCAM-1, Tie-2 and Angiostatin concentrations gradually increased together with the grade of the semiquantitative PDUS scale and concentrations of these three markers were markedly increased in patients with moderate to marked hyperemia (Power Doppler grade 2 and 3). Levels of sVCAM-1, Tie-2, and Angiostatin correlated with a global arthritis sum score, defined by the sum of the semiquantitative PDUS scores for all joints examined. Levels of Tie-2 and Placenta Growth Factor (PlGF) were associated with PDUS features indicating residual disease activity.

Conclusion

Our results support the relevance of measuring serum levels of vascular markers to evaluate the intensity and extent of synovial vascularization. Angiogenic markers, and particularly Tie-2, could be a valuable surrogate of active synovitis and their place in relation to PDUS in clinical practice deserve further investigation.

Synovitis in mice with inflammatory arthritis monitored with quantitative analysis of dynamic contrast-enhanced NIR fluorescence imaging using iRGD-targeted liposomes as fluorescence probes

BACKGROUND

Rheumatoid arthritis (RA) is a common inflammatory disorder characterized primarily by synovitis and pannus formation in multiple joints, causing joints destruction and irreversible disability in most cases. Early diagnosis and effective therapy monitoring of RA are of importance for achieving the favorable prognosis.

METHODS

We first prepared the targeted fluorescence probes, and then explored the feasibility of near-infrared (NIR) fluorescence molecular imaging to detect and evaluate the RA via the targeted fluorescence probes by quantitative analysis in this study.

RESULTS

The targeted fluorescence probes (indocyanine green-liposomes decorated with iRGD peptide [iLPs]) was successfully prepared. The quantitative analysis found that strong fluorescence signal was detected in inflamed paws and the fluorescence signal in iLPs group was 3.03-fold higher than that in non-targeted (indocyanine green-liposomes decorated without iRGD peptide [LPs]) group (P<0.01) at 15 min after injection, whereas the fluorescence signal from iLPs signal can almost not be observed in the non-inflamed paws, showing the high sensitivity and accuracy for arthritis by the NIR fluorescence imaging based on iLPs.

CONCLUSION

The NIR fluorescence imaging by iLPs may facilitate improved arthritis diagnosis and early assessment of the disease progression by providing an in vivo characterization of angiogenesis in inflammatory joint diseases.

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.

The Potential Role of Kallistatin in the Development of Abdominal Aortic Aneurysm

Abdominal aortic aneurysm (AAA) is a vascular condition that causes permanent dilation of the abdominal aorta, which can lead to death due to aortic rupture. The only treatment for AAA is surgical repair, and there is no current drug treatment for AAA. Aortic inflammation, vascular smooth muscle cell apoptosis, angiogenesis, oxidative stress and vascular remodeling are implicated in AAA pathogenesis. Kallistatin is a serine proteinase inhibitor, which has been shown to have a variety of functions, potentially relevant in AAA pathogenesis. Kallistatin has been reported to have inhibitory effects on tumor necrosis factor alpha (TNF-α) signaling induced oxidative stress and apoptosis. Kallistatin also inhibits vascular endothelial growth factor (VEGF) and Wnt canonical signaling, which promote inflammation, angiogenesis, and vascular remodeling in various pre-clinical experimental models. This review explores the potential protective role of kallistatin in AAA pathogenesis.

Inhomogeneity of immune cell composition in the synovial sublining: linear mixed modelling indicates differences in distribution and spatial decline of CD68+ macrophages in osteoarthritis and rheumatoid arthritis

Background

Inhomogeneity of immune cell distribution in the synovial sublining layer was analyzed in order to improve our mechanistic understanding of synovial inflammation and explore potential refinements for histological biomarkers in rheumatoid arthritis (RA) and osteoarthritis (OA).

Methods

Synovial tissue of 20 patients (11 RA, 9 OA) was immunohistochemically stained for macrophages (CD68), synovial fibroblasts (CD55), T cells (CD3), plasma cells (CD38), endothelial cells (vWF) and mast cells (MCT). The synovial sublining layer was divided into predefined adjacent zones and fractions of the stained area (SA) were determined by digital image analysis for each cell marker.

Results

Distribution of CD68, CD55, CD38 and MCT staining of the sublining area was heterogeneous (Friedman ANOVA p < 0.05). The highest expression for all markers was observed in the upper layer close to the lining layer with a decrease in the middle and lower sublining. The SA of CD68, CD55 and CD38 was significantly higher in all layers of RA tissue compared to OA (p < 0.05), except the CD38 fraction of the lower sublining. Based on receiver operating characteristics analysis, CD68 SA of the total sublining resulted in the highest area under the curve (AUC 0.944, CI 95 % 0.844–1.0, p = 0.001) followed by CD68 in the upper and middle layer respectively (both AUC 0.933, CI 95 % 0.816–1.0, p = 0.001) in both RA and OA. Linear mixed modelling confirmed significant differences in the SA of sublining CD68 between OA and RA (p = 0.0042) with a higher concentration of CD68+ towards the lining layer and more rapid decline towards the periphery of the sublining in RA compared to OA (p = 0.0022).

Conclusions

Immune cells are inhomogeneously distributed within the sublining layer. RA and OA tissue display differences in the number of CD68 macrophages and differences in CD68 decline within the synovial sublining.

The role of high-mobility group box protein 1 in collagen antibody-induced arthritis is dependent on vascular endothelial growth factor

High-mobility group box 1 (HMGB1) has been implicated in angiogenesis and rheumatoid arthritis (RA). The aim of this study was to define more clearly the role of HMGB1 in the synovial angiogenesis and pathogenesis of an immune model of arthritis. BALB/c mice were injected with monoclonal anti-collagen antibody cocktail followed by lipopolysaccharide to induce arthritis. HMGB1 and vascular endothelial growth factor (VEGF) were over-expressed in the areas of the synovium where more inflammation and neoangiogenesis were present. The selective blockade of HMGB1 or VEGF resulted alternatively in a lower severity of arthritis evaluated by the arthritis index. Furthermore, exogenous HMGB1 administration caused a worsening of arthritis, associated with VEGF up-regulation and increased synovial angiogenesis. The selective inhibition of VEGF also resulted in no induction of arthritis in mice receiving exogenous HMGB1. Cytokine enzyme-linked immunosorbent assay (ELISA) analyses performed on peripheral blood and synovial fluid demonstrated a significant reduction of interleukin (IL)-1β, IL-6 and tumour necrosis factor (TNF)-α in mice where HMGB1 and VEGF pathways were blocked. Interestingly, the selective blockade of HMGB1 and VEGF resulted in an increase of the peripheral IL-17A concentration. The development of arthritis mediated by HMGB1 and the synovial angiogenesis can be blocked by inhibiting the VEGF activity. The proinflammatory and proangiogenic cytokine IL-17A was increased when HMGB1 is inhibited, but the synovial angiogenesis was nevertheless reduced in this model of arthritis. Taken together, these findings shed new light on the role of this nuclear protein in the pathogenesis of arthritis in an RA-like model.

The Anti-inflammatory Effect of GV1001 Mediated by the Downregulation of ENO1-induced Pro-inflammatory Cytokine Production

GV1001 is a peptide derived from the human telomerase reverse transcriptase (hTERT) sequence that is reported to have anti-cancer and anti-inflammatory effects. Enolase1 (ENO1) is a glycolytic enzyme, and stimulation of this enzyme induces high levels of pro-inflammatory cytokines from concanavalin A (Con A)-activated peripheral blood mononuclear cells (PBMCs) and ENO1-expressing monocytes in healthy subjects, as well as from macrophages in rheumatoid arthritis (RA) patients. Therefore, this study investigated whether GV1001 downregulates ENO1-induced pro-inflammatory cytokines as an anti-inflammatory peptide. The results showed that GV1001 does not affect the expression of ENO1 in either Con A-activated PBMCs or RA PBMCs. However, ENO1 stimulation increased the production of pro-inflammatory cytokines such as tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6, and these cytokines were downregulated by pretreatment with GV1001. Moreover, p38 mitogen-activated protein kinase (MAPK) and nuclear factor (NF)-κB were activated when ENO1, on the surface of Con A-activated PBMCs and RA PBMCs, was stimulated, and they were successfully suppressed by pre-treatment with GV1001. These results suggest that GV1001 may be an effective anti-inflammatory peptide that downregulates the production of pro-inflammatory cytokines through the suppression of p38 MAPK and NF-κB activation following ENO1 stimulation.

Reduced levels of circulating progenitor cells in juvenile idiopathic arthritis are counteracted by anti TNF-α therapy

Background

Endothelial progenitor cells (EPC) promote angiogenesis and vascular repair. Though reduced EPC levels have been shown in rheumatoid arthritis, no study has so far evaluated EPCs in children with juvenile idiopathic arthritis (JIA). We aimed to study circulating EPCs in children with JIA, their relation to disease activity, and effects of anti TNF-α treatment.

Methods

Circulating EPCs were quantified by flow cytometry based on CD34, CD133 and KDR expression in peripheral blood of 22 patients with oligoarticular JIA and 29 age-matched controls. EPCs were re-assessed in children with methotrexate-resistant oligo-extended JIA before and up to 12 month after initiation of anti-TNF-alpha therapy. Plasma concentrations of inflammatory and EPC-regulating factors were measured using a multiplex array. Confocal immunofluorescence was used to demonstrate EPCs in synovial tissues.

Results

Children with active JIA showed a significant reduction of relative and absolute counts of circulating progenitor cells and EPCs compared to age-matched healthy controls. CD34⁺ cell levels were modestly and inversely correlated to disease activity. A strong inverse correlation was found between serum TNF-α and EPC levels. In 8 patients treated with anti TNF-α agents, the number of EPCs rose to values similar to healthy controls. CD34⁺KDR⁺ EPCs were found in the synovial tissue of JIA children, but not in control.

Conclusions

Children with JIA have reduced levels of the vasculoprotective and proangiogenic EPCs. While EPCs may contribute to synovial tissue remodelling, EPC pauperization may indicate an excess cardiovascular risk if projected later in life.

Endothelial progenitor cell levels in juvenile idiopathic arthritis patients: effects of anti-inflammatory therapies

BACKGROUND

Juvenile idiopathic arthritis (JIA), similarly to other arthritides, can be associated with damage of endothelial layer of which structure and function is dependent on reparative properties of endothelial progenitor cells (EPC). To date, it remained unknown whether EPC numbers are altered in young JIA patients and whether on-going anti-inflammatory therapies could exert positive effects on these progenitor cells.

METHODS

We performed a quantitative analysis of EPC numbers in 25 patients diagnosed with JIA according to International League of Associations for Rheumatism (ILAR) criteria [age 11.50 (7.50-15.00) years] in a broad context of inflammatory and cardiovascular parameters as well as different types of anti-inflammatory treatments. 11 healthy children [age 13.00 (11.00-14.00) years] were recruited as a control group.

RESULTS

We demonstrated that EPC numbers were similar in JIA patients and control subjects (0.02% vs. 0.05%, respectively, p = 0.37). EPC levels in JIA patients were negatively correlated with index of insulin resistance (rho = -0.458, p = 0.021), endogenous insulin (rho = -0.472, p = 0.017), triglyceride (rho = -0.438, p = 0.029) and TNF-alpha levels (rho = -0.446, p = 0.026). Notably, glucocorticoid (GC) therapy, was associated with detection of decreased EPC levels in JIA patients (p = 0.023). In contrast, methothrexate (MTX) and etanercept therapy in JIA patients did not affect EPC levels (p = 0.92 and p = 0.08, respectively).

CONCLUSIONS

We found that EPC numbers are maintained at normal levels in JIA patients and are not enhanced by disease-specific anti-inflammatory treatments.

PAF receptor antagonist Ginkgolide B inhibits tumourigenesis and angiogenesis in colitis-associated cancer

Platelet activating factor (PAF), a potent pro-inflammatory phospholipid, has been found to trigger tumor growth and angiogenesis through its G-protein coupled receptor (PAFR). This study was aimed to investigate the potential role of PAF in azoxymethane (AOM)/dextran sulfate sodium (DSS) induced colitis-associated cancer (CAC), using PAFR antagonist Ginkgolide B (GKB). We found GKB up-regulated serum level of PAF-AH activity. As assessed by disease activity index (DAI), histological injury scores, leukocytes infiltration, and expression of pro-inflammatory cytokines, GKB ameliorated colonic inflammation and decreased tumor number and load in mice. GKB also decreased expression of vascular endothelial growth factor (VEGF) and microvessel density (MVD) in tumor. These results suggest that PAFR antagonist might be a potential therapeutic strategy for CAC.

Role of endoplasmic reticulum stress in rheumatoid arthritis pathogenesis

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by abnormal proliferation of synoviocytes, leukocyte infiltration, and angiogenesis. The endoplasmic reticulum (ER) is the site of biosynthesis for all secreted and membrane proteins. The accumulation of unfolded proteins in the ER leads to a condition known as ER stress. Failure of the ER's adaptive capacity results in abnormal activation of the unfolded protein response. Recently, we have demonstrated that ER stress-associated gene signatures are highly expressed in RA synovium and synovial cells. Mice with Grp78 haploinsufficiency exhibit the suppression of experimentally induced arthritis, suggesting that the ER chaperone GRP78 is crucial for RA pathogenesis. Moreover, increasing evidence has suggested that GRP78 participates in antibody generation, T cell proliferation, and pro-inflammatory cytokine production, and is therefore one of the potential therapeutic targets for RA. In this review, we discuss the putative, pathophysiological roles of ER stress and GRP78 in RA pathogenesis.

The role of the tissue omega-6/omega-3 fatty acid ratio in regulating tumor angiogenesis

Angiogenesis is a necessary step in tumor growth and metastasis. It is well established that the metabolites of omega-6 and omega-3 fatty acids, which must be obtained through the diet and cannot be synthesized de novo in mammals, have differential effects on cellular processes. Omega-6 fatty acid (n-6 FA)-derived metabolites promote angiogenesis by increasing growth factor expression whereas omega-3 fatty acids (n-3 FA) have anti-angiogenic and antitumor properties. However, most studies thus far have failed to account for the role of the n-6 FA/n-3 FA ratio in angiogenesis and instead examined the absolute levels of n-6 and n-3 FA. This review highlights the biochemical interactions between n-6 and n-3 FA and focuses on how the n-6/n-3 FA ratio in tissues modulates tumor angiogenesis. We suggest that future work should consider the n-6/n-3 FA ratio to be a key element in experimental design and analysis. Furthermore, we recommend that clinical interventions should aim to both reduce n-6 metabolites and simultaneously increase n-3 FA intake.

Early intervention in the treatment of rheumatoid arthritis: focus on tocilizumab

Tocilizumab is a fully humanized monoclonal antibody against interleukin-6 receptors that was approved for the treatment of patients with rheumatoid arthritis (RA). Several lines of evidence, obtained both from conventional disease-modifying anti-rheumatic drugs (DMARDs) and tumor necrosis factor (TNF) inhibitors, have supported the concept of "window of opportunity" as showing that these therapies consistently work better in early disease as compared to established RA. This review addresses the question of whether a window of opportunity gained with conventional DMARDs and TNF inhibitors can also be achieved with tocilizumab. To this end, data regarding the use of tocilizumab in early RA patients are summarized. Currently available data suggest that the earlier the treatment with tocilizumab, the better the clinical outcome can be, which may have implications for various aspects of RA treatment strategies.

Imaging evaluation of inflammation in the musculoskeletal system: current concepts and perspectives

Inflammation is the non-specific stereotyped reaction of the musculoskeletal system to various types of aggression, such as infection, tumor, autoimmune diseases, or trauma. Precise evaluation and, increasingly, reliable quantification of inflammation are now key factors for optimal patient management, as targeted therapies (e.g., anti-angiogenesis, anti-macrophages, anti-cytokines) are emerging as everyday drugs. In current practice, inflammation is evaluated mostly using MRI and US on the basis of its non-specific extracellular component due to the increased volume of free water. Inflamed tissue is described as areas of low T1 signal and high T2 signal on magnetic resonance imaging or as hypoechogenic areas on ultrasound imaging, and the evaluation of the increased tissue vascularity can be performed using gadolinium-enhanced MRI or power Doppler US. Emerging new imaging tools, regrouped under the label "cellular and molecular imaging" and defined as the in vivo characterization and measurement of biologic processes at the cellular and molecular level, demonstrate the possible shift of medical imaging from a macroscopic and non-specific level to a microscopic and targeted scale. Cellular and molecular imaging now allows the investigation of specific pathways involved in inflammation (e.g., angiogenesis, cell proliferation, and recruitment, proteases generation, metabolism, gene expression). PET and SPECT imaging are the most commonly used "molecular" imaging modalities, but recent progress in MR, US, and optical imaging has been made. In the future, those techniques might enable a detection of inflammation at its very early stage, its quantification through the definition of biomarkers, and possibly demonstrate the response to therapy at molecular and cellular levels.

Double-antiangiogenic protein DAAP targeting vascular endothelial growth factor A and angiopoietins attenuates collagen-induced arthritis

Introduction

Angiogenesis plays a critical role in synovial inflammation and joint destruction in rheumatoid arthritis (RA). Vascular endothelial growth factor A (VEGF-A) and angiopoietins are two important mediators of synovial angiogenesis. We have previously developed a novel chimeric decoy receptor, namely, double-antiangiogenic protein (DAAP), which can both bind VEGF-A and angiopoietins and block their actions. This study was performed to evaluate the antiarthritic effect of DAAP and the combination effect with the tumor necrosis factor α (TNF-α) inhibitor in collagen-induced arthritis (CIA).

Methods

Recombinant DAAP, VEGF-Trap, Tie2-Fc and dimeric Fc proteins were produced and purified from CHO cells in large-scale bioreactors. CIA was induced in DBA/1 mice with type II collagen. The preventive effect of DAAP was determined and compared with other decoy receptors such as VEGF-Trap or Tie2-Fc, which block VEGF-A or angiopoietins, respectively. The clinical, radiographic, pathologic and immunohistochemical analyses were performed in CIA mice. The levels of matrix metalloprotease 3 (MMP-3) and interleukin 1β (IL-1β) were quantified by enzyme-linked immunosorbent assay, and receptor activator of nuclear factor κB ligand (RANKL) mRNA levels were measured by polymerase chain reaction. Finally, we investigated the combination effects of DAAP with a low dose of TNF-α decoy receptor (etanercept 10 mg/kg).

Results

On the basis of clinical and radiographic evaluation, DAAP had a much greater inhibitory effect than VEGF-Trap or Tie2-Fc on arthritis severity and bone destruction. These inhibitory effects were accompanied by significantly diminishing pathologic abnormalities, CD31-positive vasculature and synovial infiltration by F4/80-positive macrophages. The levels of MMP-3, IL-1β and RANKL were much lower in the DAAP-injected group than those of the control. Furthermore, DAAP showed a therapeutic effect and a combination effect with etanercept when injected after arthritis onset in established CIA.

Conclusions

DAAP has not only potent prophylactic effects on both inflammation and bone destruction but also therapeutic effects, alone and in combination with a TNF-α inhibitor in CIA mice. These results suggest that DAAP could be used as an effective new therapeutic agent for RA.

Differential expression of mitogen activating protein kinases in periodontitis

AIM

Following toll-like receptor (TLR) engagement, lipopolysaccharide (LPS) can stimulate the expression of pro-inflammatory cytokines thus activating the innate immune response. The production of inflammatory cytokines results, in part, from the activation of kinase-induced signalling cascades and transcriptional factors. Of the four distinct classes of mitogen-activated protein kinases (MAPK) described in mammals, p38, c-Jun N-terminal activated kinases (JNK1-3) and extracellular activated kinases (ERK1,2) are the best studied. Previous data have established that p38 MAPK signalling is required for inflammation and bone loss in periodontal disease pre-clinical animal models.

MATERIALS & METHODS

In this study, we obtained healthy and diseased periodontal tissues along with clinical parameters and microbiological parameters. Excised fixed tissues were immunostained with total and phospho-specific antibodies against p38, JNK and ERK kinases.

RESULTS

Intensity scoring from immunostained tissues was correlated with clinical periodontal parameters. Rank correlations with clinical indices were statistically significantly positive (p-value < 0.05) for total p38 (correlations ranging 0.49-0.68), phospho-p38 (range 0.44-0.56), and total ERK (range 0.52-0.59) levels, and correlations with JNK levels also supported association (range 0.42-0.59). Phospho-JNK and phospho-ERK showed no significant positive correlation with clinical parameters of disease.

CONCLUSION

These data strongly implicate p38 MAPK as a major MAPK involved in human periodontal inflammation and severity.

Inflammatory neovascularization during graft-versus-host disease is regulated by αv integrin and miR-100

Acute graft-versus-host disease (GvHD) is a complex process involving endothelial damage and neovascularization. Better understanding of the pathophysiology of neovascularization during GvHD could help to target this process while leaving T-cell function intact. Under ischemic conditions, neovascularization is regulated by different micro RNAs (miRs), which potentially play a role in inflamed hypoxic GvHD target organs. We observed strong neovascularization in the murine inflamed intestinal tract (IT) during GvHD. Positron emission tomography imaging demonstrated abundant αvβ3 integrin expression within intestinal neovascularization areas. To interfere with neovascularization, we targeted αv integrin-expressing endothelial cells, which blocked their accumulation in the IT and reduced GvHD severity independent of immune reconstitution and graft-versus-tumor effects. Additionally, enhanced neovascularization and αv integrin expression correlated with GvHD severity in humans. Expression analysis of miRs in the inflamed IT of mice developing GvHD identified miR-100 as significantly downregulated. Inactivation of miR-100 enhanced GvHD indicating a protective role for miR-100 via blocking inflammatory neovascularization. Our data from the mouse model and patients indicate that inflammatory neovascularization is a central event during intestinal GvHD that can be inhibited by targeting αv integrin. We identify negative regulation of GvHD-related neovascularization by miR-100, which indicates common pathomechanistic features of GvHD and ischemia.

Altered sequence of the ETS1 transcription factor may predispose to rheumatoid arthritis susceptibility

OBJECTIVE

ETS1 belongs to the ETS family of transcription factors that regulate the expression of various immune-related genes. The aim of this study was to identify whether the ETS1 single nucleotide polymorphism (SNP) rs11221332, described in Caucasian subjects, plays a role in rheumatoid arthritis (RA) susceptibility.

METHODS

We genotyped this polymorphism in 136 unrelated patients with RA and 147 healthy individuals with no history of autoimmune disease. Genotyping was performed with a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assay and the data were analysed using SPSS statistical software.

RESULTS

A statistically significant difference was observed in the distribution of the rs11221332 genotypes between RA patients and controls (p = 0.041). Comparing the distribution of rs11221332 alleles between the groups studied, a greater difference was found [odds ratio (OR) 1.504, 95% confidence interval (CI) 1.036-2.183; p = 0.039].

CONCLUSIONS

The present study revealed, for first time, the positive association of a polymorphism in the sequence of the ETS1 transcription factor with RA susceptibility. Further studies in other ethnic groups of patients are needed to confirm the results of the present genetic association study related to ETS1, a widely used transcription factor in the regulation of the expression of various genes.

Suppression of inflammation in a mouse model of rheumatoid arthritis using targeted lipase-labile fumagillin prodrug nanoparticles

Nanoparticle-based therapeutics are emerging technologies that have the potential to greatly impact the treatment of many human diseases. However, drug instability and premature release from the nanoparticles during circulation currently preclude clinical translation. Herein, we use a lipase-labile (Sn 2) fumagillin prodrug platform coupled with a unique lipid surface-to-surface targeted delivery mechanism, termed contact-facilitated drug delivery, to counter the premature drug release and overcome the inherent photo-instability of fumagillin, an established anti-angiogenic agent. We show that α(v)β(3)-integrin targeted fumagillin prodrug nanoparticles, administered at 0.3 mg of fumagillin prodrug/kg of body weight suppress the clinical disease indices of KRN serum-mediated arthritis in a dose-dependent manner when compared to treatment with the control nanoparticles with no drug. This study demonstrates the effectiveness of this lipase-labile prodrug nanocarrier in a relevant preclinical model that approximates human rheumatoid arthritis. The lipase-labile prodrug paradigm offers a translatable approach that is broadly applicable to many targeted nanosystems and increases the translational potential of this platform for many diseases.

A novel pathogenic role of the ER chaperone GRP78/BiP in rheumatoid arthritis

An accumulation of misfolded proteins can trigger a cellular survival response in the endoplasmic reticulum (ER). In this study, we found that ER stress-associated gene signatures were highly expressed in rheumatoid arthritis (RA) synoviums and synovial cells. Proinflammatory cytokines, such as TNF and IL-1β, increased the expression of GRP78/BiP, a representative ER chaperone, in RA synoviocytes. RA synoviocytes expressed higher levels of GRP78 than osteoarthritis (OA) synoviocytes when stimulated by thapsigargin or proinflammatory cytokines. Down-regulation of Grp78 transcripts increased the apoptosis of RA synoviocytes while abolishing TNF- or TGF-β-induced synoviocyte proliferation and cyclin D1 up-regulation. Conversely, overexpression of the Grp78 gene prevented synoviocyte apoptosis. Moreover, Grp78 small interfering RNA inhibited VEGF(165)-induced angiogenesis in vitro and also significantly impeded synoviocyte proliferation and angiogenesis in Matrigel implants engrafted into immunodeficient mice. Additionally, repeated intraarticular injections of BiP-inducible factor X, a selective GRP78 inducer, increased synoviocyte proliferation and angiogenesis in the joints of mice with experimental OA. In contrast, mice with Grp78 haploinsufficiency exhibited the suppression of experimentally induced arthritis and developed a limited degree of synovial proliferation and angiogenesis. In summary, this study shows that the ER chaperone GRP78 is crucial for synoviocyte proliferation and angiogenesis, the pathological hallmark of RA.

Inhibition of epidermal growth factor receptor tyrosine kinase ameliorates collagen-induced arthritis

Rheumatoid arthritis (RA) is an autoimmune synovitis characterized by the formation of pannus and the destruction of cartilage and bone in the synovial joints. Although immune cells, which infiltrate the pannus and promote inflammation, play a prominent role in the pathogenesis of RA, other cell types also contribute. Proliferation of synovial fibroblasts, for example, underlies the formation of the pannus, while proliferation of endothelial cells results in neovascularization, which supports the growth of the pannus by supplying it with nutrients and oxygen. The synovial fibroblasts also promote inflammation in the synovium by producing cytokines and chemokines. Finally, osteoclasts cause the destruction of bone. In this study, we show that erlotinib, an inhibitor of the tyrosine kinase epidermal growth factor receptor (EGFR), reduces the severity of established collagen-induced arthritis, a mouse model of RA, and that it does so by targeting synovial fibroblasts, endothelial cells, and osteoclasts. Erlotinib-induced attenuation of autoimmune arthritis was associated with a reduction in number of osteoclasts and blood vessels, and erlotinib inhibited the formation of murine osteoclasts and the proliferation of human endothelial cells in vitro. Erlotinib also inhibited the proliferation and cytokine production of human synovial fibroblasts in vitro. Moreover, EGFR was highly expressed and activated in the synovium of mice with collagen-induced arthritis and patients with RA. Taken together, these findings suggest that EGFR plays a central role in the pathogenesis of RA and that EGFR inhibition may provide benefits in the treatment of RA.

NF-AT5 is a critical regulator of inflammatory arthritis

OBJECTIVE

To investigate the role of NF-AT5, an osmoprotective transcription factor, in synovial hyperplasia and angiogenesis in patients with rheumatoid arthritis (RA).

METHODS

The expression of NF-AT5 in synovial tissue and synoviocytes from RA patients was examined by immunohistochemistry and Western blot analysis, respectively. Messenger RNA (mRNA) in RA synoviocytes and human umbilical vein endothelial cells (HUVECs) transfected with dummy small interfering RNA (siRNA) or NF-AT5 siRNA were profiled using microarray technology. Assays to determine synoviocyte apoptosis and proliferation were performed in the presence of NF-AT5 siRNA. VEGF₁₆₅-induced angiogenesis was assessed by measuring the proliferation, tube formation, and wound migration of HUVECs. Experimental arthritis was induced in mice by injection of anti-type II collagen antibody.

RESULTS

NF-AT5 was highly expressed in rheumatoid synovium, and its activity was increased by proinflammatory cytokines, such as interleukin-1β and tumor necrosis factor α. The mRNA profiling of synoviocytes and HUVECs transfected with NF-AT5-targeted siRNA revealed 3 major changes in cellular processes associated with the pathogenesis of RA: cell cycle and survival, angiogenesis, and cell migration. Consistent with these results, NF-AT5 knockdown in RA synoviocytes and HUVECs inhibited their proliferation/survival and impeded angiogenic processes in HUVECs. Mice with NF-AT5 haploinsufficiency (NF-AT5(+/-)) developed a very limited degree of synovial proliferation, as seen on histologic analysis, and decreased angiogenesis, and they exhibited a nearly complete suppression of experimentally induced arthritis.

CONCLUSION

NF-AT5 regulates synovial proliferation and angiogenesis in chronic arthritis.

Angiogenic activity of sera from pulmonary tuberculosis patients in relation to IL-12p40 and TNFα serum levels

The role of angiogenesis in the pathogenesis of tuberculosis (TB) is not clear. The aim of this study was to examine the effect of sera from TB patients on angiogenesis induced by different subsets of normal human mononuclear cells (MNC) in relation to IL-12p40 and TNFα serum levels. Serum samples from 36 pulmonary TB patients and from 22 healthy volunteers were evaluated. To assess angiogenic reaction the leukocytes-induced angiogenesis test according to Sidky and Auerbach was performed. IL-12p40 and TNFα serum levels were evaluated by ELISA. Sera from TB patients significantly stimulated angiogenic activity of MNC compared to sera from healthy donors and PBS (p < 0.001). The number of microvessels formed after injection of lymphocytes preincubated with sera from TB patients was significantly lower compared to the number of microvessels created after injection of MNC preincubated with the same sera (p < 0.016). However, the number of microvessels created after the injection of lymphocytes preincubated with sera from healthy donors or with PBS alone was significantly higher (p < 0.017). The mean levels of IL-12p40 and TNFα were significantly elevated in sera from TB patients compared to healthy donors. We observed a correlation between angiogenic activity of sera from TB patients and IL-12p40 and TNFα serum levels (p < 0.01). Sera from TB patients constitute a source of mediators that participate in angiogenesis and prime monocytes for production of proangiogenic factors. The main proangiogenic effect of TB patients’ sera is mediated by macrophages/monocytes. TNFα and IL-12p40 may indirectly stimulate angiogenesis in TB.

Extraluminal factors contributing to inflammatory bowel disease

Many identified and yet unknown factors contribute to the pathogenesis of inflammatory bowel disease (IBD). The genome-wide association studies clearly support the earlier developed concept that IBD occurs in genetically predisposed individuals who are exposed to distinct environmental factors, which together result in dysregulation of the mucosal immune system. Thus, the majority of previous studies have focused on the immune response within the intestinal wall. The present review aims to emphasize the contribution of three extraluminal structures to this inflammatory process, namely the mesenteric fat tissue, the lymphatics and the microvasculature. Broadening our view across the intestinal wall will not only facilitate our understanding of the disease, but will also us to identify future therapeutic targets.

The importance of neovascularization and its inhibition for allogeneic hematopoietic stem cell transplantation

GVHD and tumor relapse are fundamental problems in allogeneic HSCT. Recent research has linked neovascularization to GVHD, tumor growth, and graft-versus-tumor (GVT) activity. Damage of the endothelium by the conditioning regimen provides the initiation stimulus for recruitment of donor-derived endothelial cells and their progenitors. During the early inflammatory phase of GVHD there is considerable neovascularization facilitating migration of inflammatory cells to target organs. In the course of GVHD, however, the vasculature itself becomes a target of alloreactive donor T cells. As a consequence, later stages of GVHD are characterized by fibrosis and rarefaction of blood vessels. Importantly, the inhibition of tumor-neovascularization by activated donor T cells that release antiangiogenic substances contributes to GVT and may be enhanced by pharmacologic inhibition of neovascularization. Furthermore, the therapeutic inhibition of neovascularization may improve immunotherapy for cancer by enhancing leukocyte infiltration in tumor tissue because of normalization of tumor vessels and stimulation of leukocyte-vessel wall interactions. These insights identify important mechanisms underlining the importance of neovascularization for allogeneic immune responses and move therapeutic approaches targeting neovascularization into the spotlight. This perspective covers current knowledge of the role of neovascularization during GVHD as well as GVT and its implications for HSCT.

Obesity in rheumatoid arthritis

Obesity is a major threat for public health and its study has attracted significant attention in the general population, predominantly due to its association with significant metabolic and cardiovascular complications. In RA research, BMI is frequently reported as a demographical variable, but obesity, as such, has received little interest. This is surprising, in view of the clear associations of obesity with other arthritides, particularly OA, but also in view of the now-clear association of RA with increased cardiovascular morbidity and mortality. In this review, we summarize the studies that have looked into obesity in the RA population, evaluate their findings, identify knowledge gaps and propose directions for future research. We also pose a question of high clinical and research significance: is the use of BMI still a valid way of assessing obesity in RA?

Inhibition of neovascularization to simultaneously ameliorate graft-vs-host disease and decrease tumor growth

BACKGROUND Blood vessels are formed either by sprouting of resident tissue endothelial cells (angiogenesis) or by recruitment of bone marrow (BM)-derived circulating endothelial progenitor cells (EPCs, vasculogenesis). Neovascularization has been implicated in tumor growth and inflammation, but its roles in graft-vs-host disease (GVHD) and in tumors after allogeneic BM transplantation (allo-BMT) were not known. METHODS We analyzed neovascularization, the contribution of endothelial cells and EPCs, and the ability of anti-vascular endothelial-cadherin antibody, E4G10, to inhibit neovascularization in mice with GVHD after allo-BMT using immunofluorescence microscopy and flow cytometry. We examined survival and clinical and histopathologic GVHD in mice (n = 10-25 per group) in which GVHD was treated with the E4G10 antibody using immunohistochemistry, flow cytometry, and cytokine immunoassay. We also assessed survival, the contribution of green fluorescent protein-marked EPCs to the tumor vasculature, and the ability of E4G10 to inhibit tumor growth in tumor-bearing mice (n = 20-33 per group) after allo-BMT using histopathology and bioluminescence imaging. All statistical tests were two-sided. RESULTS We found increased neovascularization mediated by vasculogenesis, as opposed to angiogenesis, in GVHD target tissues, such as liver and intestines. Administration of E4G10 inhibited neovascularization by donor BM-derived cells without affecting host vascularization, inhibited both GVHD and tumor growth, and increased survival (at 60 days post-BMT and tumor challenge with A20 lymphoma, the probability of survival was 0.29 for control antibody-treated allo-BMT recipients vs 0.7 for E4G10-treated allo-BMT recipients, 95% confidence interval = 0.180 to 0.640, P < .001). CONCLUSIONS Therapeutic targeting of neovascularization in allo-BMT recipients is a novel strategy to simultaneously ameliorate GVHD and inhibit posttransplant tumor growth, providing a new approach to improve the overall outcome of allogeneic hematopoietic stem cell transplantation.

Anti-arthritic effect of scopoletin, a coumarin compound occurring in Erycibe obtusifolia Benth stems, is associated with decreased angiogenesis in synovium

Scopoletin is the main constituent of coumarin found in the stems of Erycibe obtusifolia Benth, a traditional Chinese medicine used in the treatment of rheumatoid arthritis. We have previously demonstrated that scopoletin is able to decrease the serum level of uric acid in hyperuricemic mice induced by potassium oxonate, and attenuate croton oil-induced inflammation. In the present study, we evaluated the anti-arthritic effects of scopoletin in rat adjuvant-induced arthritis by assessing paw swelling, pathology, and synovial angiogenesis. It was found that scopoletin, injected intraperitoneally at doses of 50, 100 mg/kg, reduced both inoculated and non-inoculated paw swelling as well as articular index scores, and elevated the mean body weight of adjuvant-induced arthritic rats. Rats treated with higher dose of scopoletin showed a near-normal histological architecture of the joints and a reduced new blood vessel formation in the synovial tissues. Furthermore, scopoletin downregulated the overexpression of vascular endothelial growth factor, basic fibroblast growth factor and interleukin 6 in the synovial tissues of adjuvant-induced arthritic rats. In conclusion, scopoletin is capable of ameliorating clinical symptoms of rat adjuvant-induced arthritis, by reducing numbers of new blood vessels in the synovium and the production of important endogenous angiogenic inducers. Therefore, this compound may be a potential agent for angiogenesis-related diseases and could serve as a structural base for screening more potent synthetic analogs.

Disease modifying and antiangiogenic activity of 2-methoxyestradiol in a murine model of rheumatoid arthritis

Background

A critical component of disease progression in rheumatoid arthritis (RA) involves neovascularization associated with pannus formation. 2-methoxyestradiol (2ME2) is a naturally occurring molecule with no known physiologic function, although at pharmacologic concentrations it has antiproliferative and antiangiogenic activities. We investigated the impact of orally administered 2ME2 on the initiation and development of proliferative synovitis using the anti-collagen monoclonal antibodies (CAIA) model.

Methods

Severe polyarticular arthritis was induced in Balb/c female mice by administration of 2 mg of a monoclonal antibody cocktail intravenously into the tail vein of mice. Twenty-four hours following monoclonal antibody administration, mice were injected with 25 μg of LPS (E. coli strain 0111:B4) via the intraperitoneal route. Treatment with 2ME2 (100, 75, 50, 25, 10, 1 mg/kg, p.o., daily), or vehicle control began 24 hrs following LPS challenge and continued to day 21. Hind limbs were harvested, sectioned and evaluated for DMARD activity and general histopathology by histomorphometric analysis and immunohistochemistry (vWF staining). In a separate study, different dosing regimens of 2ME2 (100 mg/kg; q.d. vs q.w. vs q.w. × 2) were evaluated. The effect of treatment with 2ME2 on gene expression of inflammatory cytokines and angiogenic growth factors in the joint space was evaluated 5 and 14 days after the induction of arthritis.

Results

Mice treated with 2ME2 beginning 24 hours post anti-collagen monoclonal antibody injection, showed a dose-dependent inhibition in mean arthritic scores. At study termination (day 21), blinded histomorphometric assessments of sectioned hind limbs demonstrated decreases in synovial inflammation, articular cartilage degradation, pannus formation, osteoclast activity and bone resorption. At the maximal efficacious dosing regimen (100 mg/kg/day), administration of 2ME2 resulted in total inhibition of the study parameters and prevented neovascularization into the joint. Examination of gene expression on dissected hind limbs from mice treated for 5 or 14 days with 2ME2 showed inhibition of inflammatory cytokine message for IL-1β, TNF-α, IL-6 and IL-17, as well as the angiogenic cytokines, VEGF and FGF-2.

Conclusion

These data demonstrate that in the CAIA mouse model of RA, 2ME2 has disease modifying activity that is at least partially attributable to the inhibition of neovascular development. Further, the data suggests new mechanistic points of intervention for 2ME2 in RA, specifically inhibition of inflammatory mediators and osteoclast activity.

The hypoxic synovial environment regulates expression of vascular endothelial growth factor and osteopontin in juvenile idiopathic arthritis

OBJECTIVE

Synovial angiogenesis, a critical determinant of juvenile idiopathic arthritis (JIA) pathogenesis, is sustained by various mediators, including vascular endothelial growth factor (VEGF) and osteopontin (OPN). We characterized the contribution of the local hypoxic environment to VEGF and OPN production by monocytic cells recruited to the synovium in JIA.

METHODS

Paired synovial fluid (SF) and peripheral blood (PB) samples were collected from 20 patients with JIA. Mononuclear cells (MC) were isolated, and monocytic cells were purified by adherence, maintained in a hypoxic environment, or subjected to reoxygenation. VEGF and OPN protein concentrations were tested in SF, plasma, and culture supernatants by ELISA, and mRNA expression was assessed in freshly purified and cultured cells by reverse transcriptase-polymerase chain reaction. Synovial tissue was obtained at synovectomy from 4 patients with JIA, and analyzed by immunohistochemistry for VEGF, OPN, CD68, and hypoxia-inducible factor-1alpha (HIF-1alpha).

RESULTS

VEGF mRNA expression was increased in SFMC and SF monocytic cells compared to matched PBMC and PB monocytic cells or SF lymphocytes, correlating with significantly higher protein levels in SF relative to plasma samples. Accordingly, OPN mRNA expression in SF monocytic cells was associated with significant increase of SF protein. Immunohistochemistry revealed the presence of both factors in synovial tissues at the level of the lining and sublining layers, which colocalized with intense CD68 and HIF-1alpha staining, suggesting production by hypoxic synovial monocytic cells. VEGF and OPN expression was abrogated upon SF monocytic cell reoxygenation and maintained by exposure to prolonged hypoxia.

CONCLUSION

Hypoxic synovial monocytic cells are a likely source of VEGF and OPN in JIA. These data point to a role for hypoxia in the perpetuation of synovitis in JIA.

Regulation of angiogenesis by oxygen sensing mechanisms

The choices for blood vessels to undergo angiogenesis or stay quiescent are mostly determined by the status of tissue oxygenation. A major link between tissue hypoxia and active angiogenesis is the accumulation of hypoxia-inducible factor (HIF)-alpha subunits which play a major role in the transcriptional activation of genes encoding angiogenic factors. HIF-alpha abundance is negatively regulated by a subfamily of dioxygenases referred to as prolyl hydroxylase domain-containing proteins (PHDs) which use O(2) as a substrate to hydroxylate HIF-alpha subunits and hence tag them for rapid degradation. Under hypoxic conditions, HIF-alpha subunits accumulate due to reduced hydroxylation efficiency and form transcriptionally active heterodimers with HIF-1ss to activate the expression of angiogenic factors and other proteins important for cellular adaptation to hypoxia. Angiogenesis is regulated by a combination of at least two different mechanisms. The paracrine mechanism is mediated by non-endothelial expression of angiogenic factors such as vascular endothelial growth factor (VEGF)-A, which in turn interact with endothelial cell surface receptors to initiate angiogenic activities. In the autocrine mechanism, endothelial cell themselves are induced to express VEGF-A, which collaborate with the paracrine mechanism to support angiogenesis and protect vascular integrity. Because of critical roles of PHDs and HIFs in regulating angiogenic activities, studies are underway to assess their candidacy as targets for angiogenesis therapies.

Unfractionated heparin and new heparin analogues from ascidians (chordate-tunicate) ameliorate colitis in rats

The anti-inflammatory effect of mammalian heparin analogues, named dermatan sulfate and heparin, isolated from the ascidian Styela plicata was accessed in a TNBS-induced colitis model in rats. Subcutaneous administration of the invertebrate compounds during a 7-day period drastically reduced inflammation as observed by the normalization of the macroscopic and histological characteristics of the colon. At the molecular level, a decrease in the production of TNF-alpha, TGF-beta, and VEGF was observed, as well as a reduction of NF-kappaB and MAPK kinase activation. At the cellular level, the heparin analogues attenuated lymphocyte and macrophage recruitment and epithelial cell apoptosis. A drastic reduction in collagen-mediated fibrosis was also observed. No hemorrhagic events were observed after glycan treatment. These results strongly indicate the potential therapeutic use of these compounds for the treatment of colonic inflammation with a lower risk of hemorrhage when compared with mammalian heparin.