Raised serum vascular endothelial growth factor levels are associated with destructive change in inflammatory arthritis

Rheumatoid arthritis molecular targets and their importance to flavonoid-based therapy

Rheumatoid arthritis (RA) is a progressive, chronic, autoimmune, inflammatory, and systemic condition that primarily affects the synovial joints and adjacent tissues, including bone, muscle, and tendons. The World Health Organization recognizes RA as one of the most prevalent chronic inflammatory diseases. In the last decade, there was an expansion on the available RA therapeutic options which aimed to improve patient's quality of life. Despite the extensive research and the emergence of new therapeutic approaches and drugs, there are still significant unwanted side effects associated to these drugs and still a vast number of patients that do not respond positively to the existing therapeutic strategies. Over the years, several references to the use of flavonoids in the quest for new treatments for RA have emerged. This review aimed to summarize the existing literature about the flavonoids' effects on the major pathogenic/molecular targets of RA and their potential use as lead compounds for the development of new effective molecules for RA treatment. It is demonstrated that flavonoids can modulate various players in synovial inflammation, regulate immune cell function, decrease synoviocytes proliferation and balance the apoptotic process, decrease angiogenesis, and stop/prevent bone and cartilage degradation, which are all dominant features of RA. Although further investigation is necessary to determine the effectiveness of flavonoids in humans, the available data from in vitro and in vivo models suggest their potential as new disease-modifying anti-rheumatic drugs. This review highlights the use of flavonoids as a promising avenue for future research in the treatment of RA.

Examining the functions of the vascular endothelial growth factor/hypoxia-inducible factor signaling pathway in psoriatic arthritis

Objectives

The present study aimed to examine the roles of the vascular endothelial growth factor (VEGF), hypoxia-inducible factor (HIF), and heme oxygenase-1 (HO-1) in psoriatic arthritis (PsA).

Patients and methods

In this cross-sectional study conducted between November 2020 and May 2021, 64 patients (43 female, 21 male; mean age: 43.2±10.4 years; range, 22 to 60 years) with active PsA were included in the patient group, and 64 healthy volunteers (43 female, 21 male; mean age: 42.8±10.5 years; range, 23 to 61 years) were included in the control group. The demographic features of all cases were recorded. The following indices were used to assess the activity of PsA: Bath Ankylosing Spondylitis Disease Activity Index, Disease Activity Score in 28 joints (DAS28), and Visual Analog Scale. Additionally, Disease Activity in Psoriatic Arthritis (DAPSA) and Psoriasis Area and Severity Index (PASI) were used to evaluate the patients. The biochemical parameters of the patients were calculated. The serum levels of VEGF, HIF, and HO-1 were determined using an enzyme-linked immunosorbent assay.

Results

When the molecule levels and clinical features of the groups were evaluated, it was found that the VEGF and HIF-1 levels were higher in the patient group compared to the control group (p<0.05). No difference was observed in the comparison of the HO-1 levels of the patient group and the control group (p<0.05). A positive correlation was found between VEGF, HIF-1, and HO-1 (p<0.05). A positive relationship was found between VEGF and HIF-1 and erythrocyte sedimentation rate, C-reactive protein, DAPSA score, and PASI score (p<0.05). It was also determined that there was a positive relationship between the HIF molecule and DAS28 (p<0.05).

Conclusion

According to the results obtained in the present study, VEGF and HIF play a role in the etiology of PsA, and the observation of intermolecular correlation suggests that these molecules move together in pathogenesis.

Perspective for Discovery of Small Molecule IL-6 Inhibitors through Study of Structure–Activity Relationships and Molecular Docking

Interleukin-6 (IL-6) is a proinflammatory cytokine that plays a key role in the pathogenesis and physiology of inflammatory and autoimmune diseases, such as coronary heart disease, cancer, Alzheimer's disease, asthma, rheumatoid arthritis, and most recently COVID-19. IL-6 and its signaling pathway are promising targets in the treatment of inflammatory and autoimmune diseases. Although, anti-IL-6 monoclonal antibodies are currently being used in clinics, huge unmet medical needs remain because of the high cost, administration-related toxicity, lack of opportunity for oral dosing, and potential immunogenicity of monoclonal antibody therapy. Furthermore, nonresponse or loss of response to monoclonal antibody therapy has been reported, which increases the importance of optimizing drug therapy with small molecule drugs. This work aims to provide a perspective for the discovery of novel small molecule IL-6 inhibitors by the analysis of the structure-activity relationships and computational studies for protein-protein inhibitors targeting the IL-6/IL-6 receptor/gp130 complex.

Associations among serum VEGF and CGRP levels with the peripheral vascular blood flow of the skin of the hands in women with Fibromyalgia

BACKGROUND

Fibromyalgia (FM) is a long-term condition of unknown physiopathology, whose hallmark symptoms are diffuse musculoskeletal chronic pain and fatigue.

OBJECTIVES

We aimed to analyze the associations among serum vascular endothelial growth factor (VEGF) and calcitonin gene-related peptide (CGRP) levels with the peripheral temperature of the skin of both hands and the core body temperature in patients with FM and healthy controls.

METHODS

We conducted a case-control observational study with fifty-three women diagnosed with FM and twenty-four healthy women. VEGF and CGRP levels were spectrophotometrically analyzed in serum by enzyme-linked immunosorbent assay. We used an infrared thermography camera to assess the peripheral temperature of the skin of the dorsal thumb, index, middle, ring, and pinkie fingertips and dorsal centre as well as the palm thumb, index, middle, ring, and pinkie fingertips, palm centre and thenar and hypothenar eminences of both hands and an infrared thermographic scanner to record the tympanic membrane and axillary temperature.

RESULTS

Linear regression analysis adjusting for age, menopause status, and body mass index showed that serum VEGF levels were positively associated with the maximum (β = 65.942, 95% CI [4.100,127.784], p = 0.037), minimum (β = 59.216, 95% CI [1.455,116.976], p = 0.045), and mean (β = 66.923, 95% CI [3.142,130.705], p = 0.040) temperature of the thenar eminence of the non-dominant hand, as well as with the maximum temperature of the hypothenar eminence of the non-dominant hand (β = 63.607, 95% CI [3.468,123.747], p = 0.039) in women diagnosed with FM.

CONCLUSIONS

Mild associations were observed between serum VEGF levels and the peripheral temperature of the skin in hand areas in patients with FM; therefore, it is not possible to establish a clear relationship between this vasoactive molecule and vasodilation of the hands in these patients.

Morphological and Mechanical Characterization of Extracellular Vesicles and Parent Human Synoviocytes under Physiological and Inflammatory Conditions

The morphology of fibroblast-like synoviocytes (FLS) issued from the synovial fluid (SF) of patients suffering from osteoarthritis (OA), rheumatoid arthritis (RA), or from healthy subjects (H), as well as the ultrastructure and mechanical properties of the FLS-secreted extracellular vesicles (EV), were analyzed by confocal microscopy, transmission electron microscopy, atomic force microscopy, and tribological tests. EV released under healthy conditions were constituted of several lipid bilayers surrounding a viscous inner core. This "gel-in" vesicular structure ensured high mechanical resistance of single vesicles and good tribological properties of the lubricant. RA, and to a lesser extent OA, synovial vesicles had altered morphology, corresponding to a "gel-out" situation with vesicles surrounded by a viscous gel, poor mechanical resistance, and poor lubricating qualities. When subjected to inflammatory conditions, healthy cells developed phenotypes similar to that of RA samples, which reinforces the importance of inflammatory processes in the loss of lubricating properties of SF.

TGF-β1 regulates chondrocyte proliferation and extracellular matrix synthesis via circPhf21a-Vegfa axis in osteoarthritis

Background

The transforming growth factor-beta (TGF-β) signaling pathway is an important pathway associated with the pathogenesis of osteoarthritis (OA). This study was to investigate the involvement of circRNAs in the TGF-β signaling pathway.

Methods

Cell Counting Kit-8 (CCK-8) assay and 5-ethynyl-2′-deoxyuridine (EdU) assay were used to detect the proliferation of primary mouse chondrocytes (PMCs). RNA-sequencing together with bioinformatics analysis were used to systematically clarify TGF-β1 induced alternations of circRNAs in PMCs. The regulatory and functional role of circPhf21a was examined in PMCs. Downstream targets of circPhf21a were explored by RNA-sequencing after overexpression of circPhf21a and verified by RT-qPCR in PMCs. Finally, the role and mechanism of circPhf21a in OA were explored in mouse models.

Results

We found that TGF-β1 promoted the proliferation of PMCs. Meanwhile, RT-qPCR and western blotting indicated that TGF-β1 promoted extracellular matrix (ECM) anabolism. RNA-sequencing revealed that a total of 36 circRNAs were differentially expressed between PMCs treated with and without TGF-β1. Of these, circPhf21a was significantly decreased by TGF-β1. Furthermore, circPhf21a knockdown promoted the proliferation and ECM synthesis of PMCs, whereas overexpression of circPhf21a showed the opposite effects. Mechanically, the expression profiles of the mRNAs revealed that Vegfa may be the target of circPhf21a. Additionally, we found that circPhf21a was significantly upregulated in the mouse OA model, and inhibition of circPhf21a significantly relieved the progression of OA.

Conclusions

Our results found that TGF-β1 promoted the proliferation and ECM synthesis of PMCs via the circPhf21a-Vegfa axis, which may provide novel therapeutic targets for OA treatment.

Potential value of serum brain-derived neurotrophic factor, vascular endothelial growth factor, and S100B for identifying major depressive disorder in knee osteoarthritis patients

BACKGROUND

The chronic pain and functional limitations in osteoarthritis (OA) patients can increase risk of psychiatric disorders, e.g., major depression disorder (MDD), which may further aggravate the clinical symptoms of OA. Early detection of MDD is essential in the clinical practice of OA.

MATERIALS AND METHODS

Two hundred and fifteen participants with knee OA were recruited, including 134 MDD patients (i.e., MDD group) and 81 ones without MDD (i.e., control group). Among them, 81 OA participants in the control group received a 3-year follow-up and were divided into trans-MDD group (who transforming into MDD; N = 39) and non-MDD group (who keeping non-MDD; N = 42) at the end of the follow-up. The 17-item Hamilton Depression Scale (HAMD-17), Self-Rating Depression Scale (SDS), and Visual Analogue Scale (VAS) were performed. Furthermore, serum levels of brain-derived neurotrophic factor (BDNF), vascular endothelial growth factor (VEGF), S100B, and IGF-1 were detected.

RESULTS

(1) Compared with OA participants without MDD, there were significant decrease in serum BDNF and significant increase in serum VEGF and S100B and VAS scores in OA participants with MDD. (2) A mediation of the association was found between the VAS scores and the HAMD-17 scores through the BDNF as mediator in OA participants with MDD. (3) Significantly lower baseline BDNF levels and higher baseline S100B levels were detected in OA participants who transforming to MDD after a 3-year follow-up when compared with those who keeping non-MDD. (4) In the trans-MDD group, significant associations of the change of serum BDNF levels with rate of change of HAMD-17 scores were found, and baseline serum S100B levels positively correlated with the HAMD-17 scores at the end of the follow-up. (5) In OA participants, the composite indicator of BDNF, VEGF, and S100B differentiated MDD patients from controls with the area under the curve (AUC) value of 0.806, and the combined indicator of baseline BDNF and S100B distinguished trans-MDD participants from non-MDD ones with an AUC value of 0.806.

CONCLUSION

Serum BDNF, VEGF, and S100B may be potential biomarkers to identify MDD in OA patients. Meanwhile, serum BDNF and S100B shows great potential to predict the risk of MDD for OA.

Endothelial Progenitor Cells and Rheumatoid Arthritis: Response to Endothelial Dysfunction and Clinical Evidences

Rheumatoid Arthritis (RA) is a chronic autoimmune inflammatory disease characterized by the swelling of multiple joints, pain and stiffness, and accelerated atherosclerosis. Sustained immune response and chronic inflammation, which characterize RA, may induce endothelial activation, damage and dysfunction. An equilibrium between endothelial damage and repair, together with the preservation of endothelial integrity, is of crucial importance for the homeostasis of endothelium. Endothelial Progenitor Cells (EPCs) represent a heterogenous cell population, characterized by the ability to differentiate into mature endothelial cells (ECs), which contribute to vascular homeostasis, neovascularization and endothelial repair. A modification of the number and function of EPCs has been described in numerous chronic inflammatory and auto-immune conditions; however, reports that focus on the number and functions of EPCs in RA are characterized by conflicting results, and discrepancies exist among different studies. In the present review, the authors describe EPCs' role and response to RA-related endothelial modification, with the aim of illustrating current evidence regarding the level of EPCs and their function in this disease, to summarize EPCs' role as a biomarker in cardiovascular comorbidities related to RA, and finally, to discuss the modulation of EPCs secondary to RA therapy.

Expression of VEGF-A Signaling Pathway in Cartilage of ACLT-induced Osteoarthritis Mouse Model

BACKGROUND

Anterior cruciate ligament transection surgery (ACLT)-induced OA model was often used to investigate the molecular mechanism of knee osteoarthritis (KOA). Researches have shown that vascular endothelial growth factor (VEGF) played an important role in OA. The present study aimed to investigate the pathological changes after ACLT surgery and reveal the expression characteristics of the VEGF-A/VEGFR2 signaling pathway in this model.

METHODS

Moderate KOA model was established by ACLT, and 1, 2, 4, 8, and 12 weeks after surgery, hematoxylin-eosin (HE) and Safranin-O(S-O) staining were used to detect the pathological changes in mouse knee cartilage, and the matrix biomarkers A Disintegrin and Metalloproteinase with Thrombospondin Motifs 5(ADAMTS5), Collagen II (COL-II) were detected using immunohistochemistry (IHC), CD31 was detected by immunofluorescence (IF) to show the vascular invasion in cartilage, and proteins expression of VEGF-A pathway were detected by Western blot (WB). Meanwhile, the inflammatory biomarkers cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) in cartilage were detected by WB.

RESULTS

ACLT surgery can lead to degeneration of cartilage in mice, and the characteristics of the lesion were time-dependent. The ADAMTS5-positive cells increased while COL-II decreased in OA cartilage with time, and new blood vessels labeled by CD31 can be seen from 1 week in OA cartilage, and increased in 8 and 12 weeks. The expression of VEGF-A, VEGFR2, COX-2, and iNOS were higher than control groups, which were basically consistent with the degree of osteoarthritis.

CONCLUSIONS

The degenerative degree of articular cartilage was time-dependent; angiogenesis and inflammation were important pathological changes of cartilage in KOA. The expression of the VEGF-A/VEGFR2 signaling pathway was basically correlated with the degree of KOA.

Effects of betulinic acid on synovial inflammation in rats with collagen-induced arthritis

Betulinic acid (BA) inhibits the migration, invasion, and cytoskeletal reorganization of fibroblast-like synoviocytes (RA-FLS) in patients with rheumatoid arthritis. Here, to further explore the mechanism of action of BA in collagen-induced arthritis (CIA) rats, we investigated the pharmacodynamic effects of BA on synovial inflammation in a rat model of type II CIA. After inducing hind paw swelling, the rats were divided into four groups: healthy controls (normal), and rats that underwent CIA and received methotrexate treatment (MTX), BA treatment (BA), or no treatment (CIA). Body weight and hind paw swelling were determined regularly, and arthritis scores were calculated weekly. On day 35, rats were sacrificed and their hind ankle joints sectioned and stained with hematoxylin and eosin for histopathological evaluation. BA significantly reduced CIA-induced hind paw swelling, synovial tissue proliferation, cartilage destruction, and vasospasm. BA treatment also decreased serum interleukin (IL)-1β, IL-6, and tumor necrosis factor-alpha (TNF-α) levels in rats with CIA. The CCK-8 assay was used to detect the proliferation of isolated vimentin⁺CD68^- RA-FLS; RA-FLS were stimulated with TNF-α in vitro. BA significantly inhibited TNF-α-stimulated RA-FLS proliferation, as well as IL-1β and IL-6 secretion. BA also downregulated the transcription of vascular endothelial growth factor (VEGF) and transforming growth factor β (TGF-β) and decreased the expression of the NF-кB pathway proteins (NF-kB-P65, IkBα, and IKKα/β) in the TNF-α-stimulated RA-FLS. These results indicate that BA alleviated the symptoms of CIA by inhibiting synoviocyte proliferation, modifying TNF-α- and NF-кB-related inflammatory pathways, and downregulating inflammatory mediators and growth factors including IL-1β, IL-6, VEGF, and TGF-β.

Association of Circulating Vascular Endothelial Growth Factor Levels With Autoimmune Diseases: A Systematic Review and Meta-Analysis

Background

Autoimmune diseases (ADs) are characterized by immune-mediated tissue damage, in which angiogenesis is a prominent pathogenic mechanism. Vascular endothelial growth factor (VEGF), an angiogenesis modulator, is significantly elevated in several ADs including rheumatoid arthritis (RA), systemic sclerosis (SSc), and systemic lupus erythematosus (SLE). We determined whether circulating VEGF levels were associated with ADs based on pooled evidence.

Methods

The analyses included 165 studies from the PubMed, EMBASE, Cochrane Library, and Web of Science databases and fulfilled the study criteria. Comparisons of circulating VEGF levels between patients with ADs and healthy controls were performed by determining pooled standard mean differences (SMDs) with 95% confidence intervals (CIs) in a random-effect model using STATA 16.0. Subgroup, sensitivity, and meta-regression analyses were performed to determine heterogeneity and to test robustness.

Results

Compared with healthy subjects, circulating VEGF levels were significantly higher in patients with SLE (SMD 0.84, 95% CI 0.25-1.44, P = 0.0056), RA (SMD 1.48, 95% CI 0.82-2.15, P <0.0001), SSc (SMD 0.56, 95% CI 0.36-0.75, P <0.0001), Behcet's disease (SMD 1.65, 95% CI 0.88-2.41, P <0.0001), Kawasaki disease (SMD 2.41, 95% CI 0.10-4.72, P = 0.0406), ankylosing spondylitis (SMD 0.78, 95% CI 0.23-1.33, P = 0.0052), inflammatory bowel disease (SMD 0.57, 95% CI 0.43-0.71, P <0.0001), psoriasis (SMD 0.98, 95% CI 0.62-1.34, P <0.0001), and Graves' disease (SMD 0.69, 95% CI 0.20-1.19, P = 0.0056). Circulating VEGF levels correlated with disease activity and hematological parameters in ADs.

Conclusion

Circulating VEGF levels were associated with ADs and could predict disease manifestations, severity and activity in patients with ADs.

Systematic Review Registration

PROSPERO, identifier CRD42021227843.

Biomarkers in Rheumatoid Arthritis

The utilization and identification of biomarkers in rheumatoid arthritis (RA) to facilitate timely diagnosis and the optimal management of the disease is an area of active investigation. This review focuses on biomarkers available for routine clinical use, details potential investigational biomarkers, and raises outstanding clinical questions.

Effects of All-Trans Retinoic Acid on the Optimization of Synovial Explant Induced by Tumor Necrosis Factor Alpha

Current studies focused on the effects of all-trans-retinoic acid (ATRA) on synovial explants from rats with rheumatoid arthritis (RA) induced by lipopolysaccharides (LPS). In our study, synovial membranes were extracted aseptically from the quadriceps femoris of the knee joint of rats, and then incubated in medium containing 10% neonate bovine serum for 24 h adaptive culture. We first measured variations of correlation factors in synovium at 24, 48, 72, 96 and 120 h in control medium or in medium containing 20 ng/mL tumor necrosis factor alpha (TNF-α) (TNF-α-experiment). Then, we investigated the synovium exposed to three ATRA concentrations after 48 h incubation (ATRA-experiment). The effects of ATRA on synovitis were evaluated by observing the expression of inflammatory cytokines, angiogenic factors and the production of proteases in nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) pathway and apoptosis and autophagy. In TNF-α-experiment, the secretion of nitric oxide (NO), interleukin-6 (IL-6), vascular endothelial growth factor (VEGF), and matrix metalloproteinase-9 (MMP-9) increased significantly after TNF-α stimulation without pathological damage to the synovium. Hence, we successfully obtained the synovial explants model, which had longer inflammatory response time. In the ATRA-experiment, ATRA suppressed the secretion of IL-6 and NO, downregulated the NF-κB P65 and Bcl-2, increased levels of autophagy marker protein LC3, but different doses of ATRA showed inconsistent regulatory effects on VEGF and MMP-9. In short, ATRA inhibited TNF-α induced synovitis by the regulation of inflammatory cytokines and inhibiting NF-κB signal transduction and potentially promoting autophagy, apoptosis and angiogenesis, displaying its role in alleviating synovial inflammation in patients with RA.

The sFlt-1 to PlGF Ratio in Pregnant Women with Rheumatoid Arthritis: Impact of Disease Activity and Sulfasalazine Use

OBJECTIVES

An elevated sFlt-1/PlGF-ratio has been validated as a significant predictor of preeclampsia, but has not been established in women with rheumatoid arthritis (RA). We explored whether the sFlt-1/PlGF-ratio could be altered due to disease activity in RA, and could be applied in this population to predict preeclampsia. Since sulfasalazine has been suggested to improve the angiogenic imbalance in preeclampsia, we also aimed to examine whether sulfasalazine could affect sFlt-1 or PlGF levels.

METHODS

Making use of a nationwide, observational, prospective cohort study on pregnant women with RA, sFlt-1 and PlGF were measured in the third trimester. A total of 221 women, aged 21-42 years, were included, with a median gestational age of 30 + 3 weeks.

RESULTS

No differences in sFlt-1 or PlGF were observed between women with high, intermediate or low disease activity (p= 0.07 and p= 0.41), whereas sFlt-1 and PlGF did not correlate with DAS28-CRP score (r=-0.01 and r=-0.05, respectively). Four (2%) women with a sFlt-1/PlGF-ratio ≤38 developed preeclampsia in comparison to three (43%) women with a ratio > 38, corresponding to a negative predictive value of 98.1%. Sulfasalazine users (n = 57) did not show altered levels of sFlt-1 or PlGF in comparison to non-sulfasalazine users (n = 164, p= 0.91 and p= 0.11).

CONCLUSION

Our study shows that in pregnant women with RA, the sFlt-1/PlGF-ratio is not altered due to disease activity and a cut-off ≤38 can be used to exclude preeclampsia. Additionally, sulfasalazine use did not affect sFlt-1 or PlGF levels in this population.

Blood in the joint: effects of hemarthrosis on meniscus health and repair techniques

Injury to the meniscus is common and frequently leads to the development of post-traumatic osteoarthritis (PTOA). Many times meniscus injuries occur coincident with anterior cruciate ligament (ACL) injuries and lead to a bloody joint effusion. Hemarthrosis, or bleeding into the joint, has been implicated in degeneration of joint tissues. The goal of this review paper is to understand the pathophysiology of blood-induced joint damage, the possible effects of blood on meniscus tissue, and the implications for current meniscus repair techniques that involve the introduction of blood-derived products into the joint. In this review, we illustrate the similarities in the pathophysiology of joint damage due to hemophilic arthropathy (HA) and osteoarthritis (OA). Although numerous studies have revealed the harmful effects of blood on cartilage and synovium, there is currently a gap in knowledge regarding the effects of hemarthrosis on meniscus tissue homeostasis, healing, and the development of PTOA following meniscus injury. Given that many meniscus repair techniques utilize blood-derived and marrow-derived products, it is essential to understand the effects of these factors on meniscus tissue and the whole joint organ to develop improved strategies to promote meniscus tissue repair and prevent PTOA development.

The Relationship Between Serum Angiogenic Factor Levels and Disease Activity in Rheumatoid Arthritis

Objectives

This study aims to evaluate the relationship between serum angiogenic factor levels and disease activity in patients with rheumatoid arthritis (RA) using both clinical and dynamic wrist magnetic resonance imaging (MRI) data.

Patients and methods

Simultaneous serum angiogenesis markers [vascular endothelial growth factor (VEGF), angiopoietin-1 (ANG1), ANG2, and tyrosine-protein kinase receptor for angiopoietin (Tie-2)] were studied in 40 patients with RA (13 males, 27 females; mean age 51.1±10.8 years; range, 23 to 69 years) and 20 healthy controls (11 males, 9 females; mean age 47.3±12.8 years; range, 29 to 69 years) and dynamic contrast-enhanced wrist MRI was performed in 40 RA patients and seven controls. Rate of early in 55th second (REE) and Relative enhancement (REt) values were calculated from the signal time curve values obtained from the analysis of images. In clinical assessment, duration of morning stiffness, patient pain assessment [visual analog scale (VAS)], physician and patient global assessments (VAS) were recorded. The number of tender joints and swollen joints were determined. Disease activity score 28 and Ritchie scores were calculated. Health assessment questionnaire was used for functional evaluation. Anti-cyclic citrullinated peptide, rheumatoid factor, erythrocyte sedimentation rate and high sensitive C-reactive protein analyses were performed.

Results

Serum VEGF, REE and REt values were significantly higher in RA patients than healthy controls (p=0.002, p=0.00, p=0.00, respectively). There was no significant correlation between serum angiogenesis markers and clinical parameters or REE and REt (p>0.05). VEGF value correlated positively with disease duration (p=0.024).

Conclusion

Serum VEGF was higher in RA patients. While its level was associated with disease duration, no significant correlation was found with disease activity. As a diagnostic test, dynamic contrast-enhanced MRI was a valuable method for showing disease activity.

Gene polymorphisms and serum levels of sVEGFR-1 in patients with systemic lupus erythematosus

Correlation between soluble vascular endothelial growth factor receptor-1 (sVEGFR-1) concentration, VEGFR1 gene polymorphisms and systemic lupus erythematosus (SLE) risk remains unclear. The present case–control study comprised 254 SLE patients, 385 other rheumatic diseases patients and 390 healthy controls. Serum levels of sVEGFR-1 were detected by enzyme-linked immunosorbent assay. Seven VEGFR1 genetic variants (rs2296188, rs9943922, rs2296283, rs7324510, rs9554322, rs9582036, rs9554320) were genotyped by KASP. Serum levels of sVEGFR-1 were up-regulated in SLE and positively correlated with disease activity. Furthermore, serum sVEGFR-1 presented a distinctive elevation in SLE in comparison with other rheumatic diseases. Frequencies of allele T of rs2296283 and allele G of rs9554322 were significant lower in SLE patients (P = 0.003, P = 0.004). Frequencies of genotypes TT of rs2296188 and rs2296283 were declined in patients compared with healthy controls (P = 0.039, P = 0.033). CC genotype of rs7324510 and rs9582036 was negatively correlated with SLE risk (OR = 0.538, OR = 0.508). Distribution of GG, GC, GG + GC genotypes of rs9554322 were different between SLE patients and healthy controls (P = 0.027, P = 0.036, P = 0.010). Moreover, frequency of TC genotype of rs7324510 was higher in SLE patients with lupus headache (χ² = 9.924, P = 0.039) and frequency of TC genotype of rs9943922 was lower in patients with cylindruriain (χ² = 7.589, P = 0.026). Frequencies of allele C of rs7324510 and allele T of rs9943922 were decreased in SLE patients with cylindruria and hypocomplementemia, respectively (χ² = 4.195, P = 0.041, χ² = 3.971, P = 0.046). However, frequency of allele C of rs9554322 was increased in SLE patients with pyuria (χ² = 11.702, P = 0.001). In addition, SLE patients carrying GG, GC, CC genotypes for rs9554322 had higher levels of serum sVEGFR-1. In conclusion, serum sVEGFR-1 was elevated in SLE patients and may be a disease marker. VEGFR1 gene polymorphisms related to risk of SLE in a Chinese Han population.

Understanding the immunopathogenesis of autoimmune diseases by animal studies using gene modulation: A comprehensive review

Autoimmune diseases are clinical syndromes that result from pathogenic inflammatory responses driven by inadequate immune activation by T- and B-cells. Although the exact mechanisms of autoimmune diseases are still elusive, genetic factors also play an important role in the pathogenesis. Recently, with the advancement of understanding of the immunological and molecular basis of autoimmune diseases, gene modulation has become a potential approach for the tailored treatment of autoimmune disorders. Gene modulation can be applied to regulate the levels of interleukins (IL), tumor necrosis factor (TNF), cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4), interferon-γ and other inflammatory cytokines by inhibiting these cytokine expressions using short interfering ribonucleic acid (siRNA) or by inhibiting cytokine signaling using small molecules. In addition, gene modulation delivering anti-inflammatory cytokines or cytokine antagonists showed effectiveness in regulating autoimmunity. In this review, we summarize the potential target genes for gene or immunomodulation in autoimmune diseases including rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), inflammatory bowel diseases (IBD) and multiple sclerosis (MS). This article will give a new perspective on understanding immunopathogenesis of autoimmune diseases not only in animals but also in human. Emerging approaches to investigate cytokine regulation through gene modulation may be a potential approach for the tailored immunomodulation of some autoimmune diseases near in the future.

Receptor targeting drug delivery strategies and prospects in the treatment of rheumatoid arthritis

Rheumatoid arthritis (RA), a chronic inflammatory disease, is characterized by cartilage damage, bone tissue destruction, morphological changes in synovial fluids, and synovial joint inflammation. The inflamed synovial tissue has potential for passive and active targeting because of enhanced permeability and retention effect and the existence of RA synovial macrophages and fibroblasts that selectively express surface receptors such as folate receptor β, CD44 and integrin αVβ. Although there are numerous interventions in RA treatment, they are not safe and effective. Therefore, it is important to develop new drug or drug delivery systems that specifically targets inflamed/swollen joints but attenuates other possible damages to healthy tissues. Recently some receptors such as toll-like receptors (TLRs), the nucleotide-binding oligomerization domain-like receptors, and Fc-γ receptor have been identified in synovial tissue and immune cells that are involved in induction or suppression of arthritis. Analysis of the TLR pathway has moreover suggested new insights into the pathogenesis of RA. In the present paper, we have reviewed drug delivery strategies based on receptor targeting with novel ligand-anchored carriers exploiting CD44, folate and integrin αVβ as well as TLRs expressed on synovial monocytes and macrophages and antigen presenting cells, for possible active targeting in RA. TLRs could not only open a new horizon for developing new drugs but also their antagonists or humanized monoclonal antibodies that block TLRS specially TLR4 and TLR9 signaling could be used as targeting agents to antigen presenting cells and dendritic cells. As a conclusion, common conventional receptors and multifunctional ligands that arte involved in targeting receptors or developing nanocarriers with appropriate ligands for TLRs can provide profoundly targeting drug delivery systems for the effective treatment of RA.

Dysregulated miR-125a promotes angiogenesis through enhanced glycolysis

Background

Although neoangiogenesis is a hallmark of chronic inflammatory diseases such as inflammatory arthritis and many cancers, therapeutic agents targeting the vasculature remain elusive. Here we identified miR-125a as an important regulator of angiogenesis.

Methods

MiRNA levels were quantified in Psoriatic Arthritis (PsA) synovial-tissue by RT-PCR and compared to macroscopic synovial vascularity. HMVEC were transfected with anti-miR-125a and angiogenic mechanisms quantified using tube formation assays, transwell invasion chambers, wound repair, RT-PCR and western blot. Real-time analysis of EC metabolism was assessed using the XF-24 Extracellular-Flux Analyzer. Synovial expression of metabolic markers was assessed by immunohistochemistry and immunofluorescent staining. MiR-125a CRISPR/Cas9-based knock-out zebrafish were generated and vascular development assessed. Finally, glycolytic blockade using 3PO, which inhibits Phosphofructokinase-fructose-2,6-bisphophatase 3 (PFKFB3), was assessed in miR-125a−/− ECs and zebrafish embryos.

Findings

MiR-125a is significantly decreased in PsA synovium and inversely associated with macroscopic vascularity. In-vivo, CRISPR/cas9 miR-125a^−/− zebrafish displayed a hyper-branching phenotype. In-vitro, miR-125a inhibition promoted EC tube formation, branching, migration and invasion, effects paralleled by a shift in their metabolic profile towards glycolysis. This metabolic shift was also observed in the PsA synovial vasculature where increased expression of glucose transporter 1 (GLUT1), PFKFB3 and Pyruvate kinase muscle isozyme M2 (PKM2) were demonstrated. Finally, blockade of PFKFB3 significantly inhibited anti-miR-125a-induced angiogenic mechanisms in-vitro, paralleled by normalisation of vascular development of CRISPR/cas9 miR-125a^−/− zebrafish embryos.

Intepretation

Our results provide evidence that miR-125a deficiency enhances angiogenic processes through metabolic reprogramming of endothelial cells.

Fund

Irish Research Council, Arthritis Ireland, EU Seventh Framework Programme (612218/3D-NET).

KDR (VEGFR2) Genetic Variants and Serum Levels in Patients with Rheumatoid Arthritis

We investigated kinase insert domain-containing receptor (KDR) polymorphisms and protein levels in relation to susceptibility to and severity of Rheumatoid Arthritis (RA). 641 RA patients and 340 controls (HC) were examined for the rs1870377 KDR variant by the polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP) method and for rs2305948 and rs2071559 KDR single nucleotide polymorphisms (SNPs) by TaqMan SNP genotyping assay. KDR serum levels were determined by enzyme-linked immunosorbent assay (ELISA). The rs1870377 KDR variant has shown association with RA under the codominant (p = 0.02, OR = 1.76, 95% CI = 1.09–2.85) and recessive models (p = 0.019, OR = 1.53, 95% CI = 1.07–2.20). KDR rs2305948 was associated with RA under the dominant model (p = 0.005, OR = 1.38, 95% CI = 1.10–1.73). Under the codominant model, the frequency of the rs2071559 TC and GG genotypes were lower in RA patients than in controls (p < 0.001, OR = 0.51, 95% CI = 0.37–0.69, and p = 0.002, OR = 0.57, 95% CI = 0.39–0.81). KDR rs2071559 T and rs2305948 A alleles were associated with RA (p = 0.001, OR = 0.60, 95% CI = 0.45–0.81 and p = 0.008, OR = 1.71, CI = 1.15–2.54). KDR rs2305948SNP was associated with Disease Activity Score (DAS)-28 score (p < 0.001), Visual Analog Scale (VAS) score (p < 0.001), number of swollen joints (p < 0.001), mean value of CRP (p < 0.001). A higher KDR serum level was found in RA patients than in HC (8018 pg/mL versus 7381 pg/mL, p = 0.002). Present results shed light on the role of KDR genetic variants in the severity of RA.

IL-35, TNF-α, BAFF, and VEGF serum levels in patients with different rheumatic diseases

Objectives

Inflammatory processes in rheumatic diseases spread via various types of immune system cells and tissues with the aid of inflammatory cytokines and growth factors and the participation of vascular endothelium. Research is still conducted to determine the role of individual factors in the pathophysiology of rheumatic diseases. The task is complicated because the multiplane network of cytokines is characterized by complex correlations manifesting as positive and negative feedback, which impedes the definitive interpretation of the role of specific cytokines. Therefore, it seems justified to perform a comparative analysis of the expression of at least several molecules in one study, which may help reveal their role in the pathogenesis of rheumatic diseases and have prognostic value.

Material and methods

The aim of the study involves the assessment and comparative analysis of the concentrations of interleukin 35 (IL-35), tumour necrosis factor α (TNF-α), B-cell-activating factor (BAFF), and vascular endothelial growth factor (VEGF) in peripheral blood serum in patients with rheumatoid arthritis (RA) (n = 43), systemic lupus erythematosus (SLE) (n = 28), antiphospholipid syndrome (APS) (n = 24), and mixed connective tissue disease (MCTD) (n = 9). The main intention is to search for biomarkers for specific rheumatic diseases. Cytokine and growth factor levels were determined using specific ELISA kits.

Results

Statistically significant differences in VEGF and IL-35 concentrations occurred between patients with APS vs. RA and SLE vs. RA. There was a significant high positive correlation between the concentration of BAFF and TNF-α (r = 0.77, p < 0.0000) in patients with APS, as well as in patients with SLE (r = 0.55, p = 0.00).

Conclusions

BAFF and TNF-α may be promising biomarkers in patients with APS and VEGF in patients with RA. Additionally, IL-35 may be a useful marker for the diagnosis of APS. Positive correlation of BAFF and TNF-α concentrations in APS and SLE potentially indicates much more similar etiopathogenesis of these diseases than it could be previously predicted.

Correlation between circulating VEGF levels and disease activity in rheumatoid arthritis: a meta-analysis

OBJECTIVE

To systematically review evidence regarding the relationship between circulating vascular endothelial growth factor (VEGF) levels and rheumatoid arthritis (RA), the correlation between serum VEGF levels and RA activity, and the association between VEGF polymorphisms and RA susceptibility.

METHODS

We conducted a meta-analysis of the serum/plasma VEGF levels in patients with RA and controls, the correlation coefficients between the circulating VEGF levels and disease activity in patients with RA, and the association between VEGF -2578 A/C, -634 C/G, +936 T/C, and -1154 A/G polymorphisms and the risk for RA.

RESULTS

In total, 13 studies including 2508 patients with RA and 2489 controls were included. Meta-analysis revealed that VEGF level was significantly higher in the RA than in the control group (standard mean difference [SMD] = 1.480, 95% confidence interval [CI] = 0.71-2.241, p = 1.4 × 10^-4). Stratification by adjustment for age and gender revealed significantly higher VEGF levels for the adjustment and non-adjustment groups in the RA group (SMD = 1.360, 95% CI = 0.445-2.276, p = 0.004; SMD = 1.557, 95% CI = 0.252-2.861, p = 0.019, respectively). Meta-analysis of correlation coefficients showed a significantly positive correlation between circulating VEGF levels and disease activity in RA, and between circulating VEGF and C‑reactive protein levels. However, no association was found between RA and the VEGF -2578 A/C, -634 C/G, +936 T/C, and -1154 A/G polymorphisms.

CONCLUSION

Our meta-analysis revealed significantly higher circulating VEGF levels in patients with RA and a positive correlation between VEGF levels and disease activity in RA, but no association between the VEGF -2578 A/C, -634 C/G, +936 T/C, and -1154 A/G polymorphisms and the development of RA.

A fresh look at angiogenesis in juvenile idiopathic arthritis

Angiogenesis is the complex process of creating new capillaries from preexisting blood vessels due to hypoxemia, injury or inflammation of the tissues. Numerous cytokines and cell mediators have been identified to induce and stimulate angiogenesis, but vascular endothelial growth factor (VEGF) is a key regulator. The role of proangiogenic factors in the pathogenesis of chronic arthritis is currently a subject of intensive investigations in adult patients with rheumatoid arthritis (RA) and, to a limited extent, in children with juvenile idiopathic arthritis (JIA). Recent studies has shown a significant correlation between proangiogenic marker concentrations and the severity of inflammation in either RA or JIA patients. The serum neovascularization markers correlate with the power Doppler ultrasound image of the inflamed joint and hypertrophic synovium, which may be connected with the disease activity.

The aim of this paper is to describe the state of the art on the important role of angiogenesis in adult and childhood rheumatoid arthritis.

Vascular endothelial growth factor expression and their action in the synovial membranes of patients with painful knee osteoarthritis

BACKGROUND

Research suggests that vascular endothelial growth factor (VEGF) levels in the synovial fluid of knee osteoarthritis (KOA) patients are positively correlated with KOA severity. The relationship between synovial VEGF levels and pain in human KOA patients is not fully understood, and the role of VEGF in the pain pathway remains unclear.

METHODS

We harvested synovial membrane (SM) from 102 patients with radiographic evidence of KOA (unilateral Kellgren/Lawrence [K/L] grade 2-4) during total knee arthroplasty. Patients scored their pain on a 0 to 10 cm visual analog scale (VAS). VEGF levels in the SM of KOA patients with strong/severe (VAS ≥ 6) and mild/moderate pain (VAS < 6) were compared. Correlations between VAS and VEGF mRNA expression were investigated. To investigate a possible mechanism for VEGF-induced pain, the distribution of VEGF and the neuropeptide apelin was determined by immunohistochemical analyses. To investigate the role of VEGF in regulating apelin expression, SM cells were exposed to VEGF.

RESULTS

VEGF expression in the VAS ≥ 6 group was significantly greater than expression in the VAS < 6 group. Expression levels of VEGF were also positively correlated with VAS. VEGF-positive cells were identified in the lining of the SM. Expression of apelin mRNA and protein were significantly elevated in SM cells treated with exogenous VEGF compared to those treated with vehicle.

CONCLUSION

Synovial VEGF may be involved in pain pathways in KOA and its action may be mediated by apelin.

Vascular Morphogenesis in the Context of Inflammation: Self-Organization in a Fibrin-Based 3D Culture System

Introduction: New vessel formation requires a continuous and tightly regulated interplay between endothelial cells with cells of the perivascular microenvironment supported by mechanic-physical and chemical cues from the extracellular matrix. Aim: Here we investigated the potential of small fragments of synovial tissue to form de novo vascular structures in the context of inflammation within three dimensional (3D) fibrin-based matrices in vitro, and assessed the contribution of mesenchymal stromal cell (MSC)-immune cell cross-talk to neovascularization considering paracrine signals in a fibrin-based co-culture model. Material and Methods: Synovial tissue fragments from patients with rheumatoid arthritis (RA) and inflammatory osteoarthritis (OA) were cultivated within 3D fibrin matrices for up to 4 weeks. Cellular and structural re-arrangement of the initially acellular matrix were documented by phase contrast microscopy and characterized by confocal laser-scanning microscopy of topographically intact 3D cultures and by immunohistochemistry. MSC-peripheral blood mononuclear cell (PBMC) co-cultures in the 3D fibrin system specifically addressed the influence of perivascular cell interactions to neo-vessel formation in a pro-inflammatory microenvironment. Cytokine levels in the supernatants of cultured explant tissues and co-cultures were evaluated by the Bio-Plex cytokine assay and ELISA. Results: Vascular outgrowth from the embedded tissue into the fibrin matrix was preceded by leukocyte egress from the tissue fragments. Neo-vessels originating from both the embedded sample and from clusters locally formed by emigrated mononuclear cells were consistently associated with CD45⁺ leukocytes. MSC and PBMC in co-culture formed vasculogenic clusters. Clusters and cells with endothelial phenotype emerging from them, were surrounded by a collagen IV scaffold. No vascular structures were observed in control 3D monocultures of PBMC or MSC. Paracrine signals released by cultured OA tissue fragments corresponded with elevated levels of granulocyte-colony stimulating factor, vascular endothelial growth factor and interleukin-6 secreted by MSC-PBMC co-cultures. Conclusion: Our results show that synovial tissue fragments with immune cell infiltrates have the potential to form new vessels in initially avascular 3D fibrin-based matrices. Cross-talk and cluster formation of MSC with immune cells within the 3D fibrin environment through self-organization and secretion of pro-angiogenic paracrine factors can support neo-vessel growth.

Anti-angiogenic effects of biotechnological therapies in rheumatic diseases

Introduction

Angiogenesis plays a key role in the pathogenesis of numerous rheumatic diseases, such as rheumatoid arthritis, psoriatic arthritis, and vasculitides. Therefore, the inhibition of pathological angiogenesis may be considered a useful therapeutical approach in these rheumatic diseases.

Methods

This review article is based on a literature research about the role of biotechnological therapies in angiogenesis inhibition.

Results and conclusions

Several evidences have demonstrated a role for biotechnological therapies in angiogenesis inhibition. Nevertheless, further research and clinical trials are needed to better quantify the real impact of biotechnological therapies on pathological angiogenesis.

Sorafenib Reveals Anti-Arthritic Potentials in Collagen Induced Experimental Arthritis Model

Objectives

This study aims to examine the effects of sorafenib on a collagen-induced arthritis model.

Materials and methods

The study included 50 randomly selected female Wistar-albino rats (8-10-week-old, weighing between 200 g to 250 g). The rats were divided into five equal groups as control, arthritis, etanercept, sorafenib high-dose, and sorafenib low-dose groups, respectively. Arthritis was induced by injecting mixed intradermal chicken type II collagen and incomplete Freund's adjuvant. Twenty-four hours after the advent of arthritis; rats in group 3 were injected subcutaneous etanercept (6 mg/kg/week), while those in groups 4 and 5 were given sorafenib (10 or 30 mg/ kg/day) orally until they were sacrificed on the 34th day. The rat claws and trunk bloods were carefully examined to note perisynovial inflammation and cartilage/bone injury through histopathology. Tissue vascular endothelial growth factor (VEGF) and VEGF receptor levels were carefully checked using western blot analysis.

Results

Analysis of the experimental data showed that collagen-induced arthritis decreased in treatments groups after 12-13 days and 34th day in contrast with the arthritis group. Histopathological examination revealed broad perisynovial inflammation and cartilage/bone break down in the arthritis group. Compared to the control group, tissue VEGF and VEGF receptor levels increased in the arthritis group. Sorafenib and etanercept decreased tissue VEGF and VEGF receptor levels, perisynovial inflammation, damage of cartilage/bone.

Conclusion

Our findings indicate that sorafenib treatment ameliorates collagen-induced arthritis with anti-VEGF effectiveness.

Friends Turned Foes: Angiogenic Growth Factors beyond Angiogenesis

Angiogenesis, the formation of new blood vessels from pre-existing ones is a biological process that ensures an adequate blood flow is maintained to provide the cells with a sufficient supply of nutrients and oxygen within the body. Numerous soluble growth factors and inhibitors, cytokines, proteases as well as extracellular matrix proteins and adhesion molecules stringently regulate the multi-factorial process of angiogenesis. The properties and interactions of key angiogenic molecules such as vascular endothelial growth factors (VEGFs), fibroblast growth factors (FGFs) and angiopoietins have been investigated in great detail with respect to their molecular impact on angiogenesis. Since the discovery of angiogenic growth factors, much research has been focused on their biological actions and their potential use as therapeutic targets for angiogenic or anti-angiogenic strategies in a context-dependent manner depending on the pathologies. It is generally accepted that these factors play an indispensable role in angiogenesis. However, it is becoming increasingly evident that this is not their only role and it is likely that the angiogenic factors have important functions in a wider range of biological and pathological processes. The additional roles played by these molecules in numerous pathologies and biological processes beyond angiogenesis are discussed in this review.

Angiogenesis Dysregulation in Psoriatic Arthritis: Molecular Mechanisms

There is evidence that psoriatic arthritis is closely linked to angiogenesis. Morphological changes described in blood vessels of psoriatic arthritis joints suggest the presence of a dysregulated angiogenesis resulting in the formation of immature vessels. Even if the reason of this inefficient angiogenesis is still unclear, an imbalance between angiogenic and antiangiogenic factors is probably responsible for inducing a dysregulated angiogenesis in psoriatic arthritis, which seems to be involved in its pathogenesis and clinical features. Nevertheless, among chronic arthritides, while angiogenesis in rheumatoid arthritis has been largely studied with a great amount of literature data, limited data on angiogenesis role in psoriatic arthritis are available. This review article is focused on current knowledge on the mechanisms responsible for dysregulated angiogenesis in psoriatic arthritis.

[Polymorphism in the regulatory regions -С2578A and +C936T of the vascular endothelial growth factor (VEGF-A) gene in Russian women with rheumatoid arthritis]

AIM

To analyze polymorphism in the regulatory regions of the vascular endothelial growth factor (VEGF) gene in female patients with rheumatoid arthritis (RA).

SUBJECTS AND METHODS

The investigation enrolled 257 female patients with RA. A control group consisted of 297 women without chronic diseases. The investigators examined the single-nucleotide polymorphism of VEGF-А2578С in the promoter region (rs699947) and that of VEGF+С936Т 3 in the retranslated region (rs3025039) of the gene. Genotyping was performed by restriction fragment length polymorphism analysis.

RESULTS

There was an increase in the frequency of VEGF+936 CT and a reduction in that of the VEGF+936СС genotypes in the seronegative patients as compared to the healthy women. The VEGF+936СС genotype frequency was higher in the patients with seropositive RA than in the subgroup of seronegative patients. The frequency of the VEGF-2578СС genotype was increased in the patients with RA and rheumatoid nodules, as compared to the healthy women.

CONCLUSION

The data presented suggest that the presence of certain VEGF gene variants located in the regulatory regions may reflect the nature of immunopathological mechanisms in RA.

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.

Arthritis models: usefulness and interpretation

Animal models of arthritis are used to better understand pathophysiology of a disease or to seek potential therapeutic targets or strategies. Focusing on models currently used for studying rheumatoid arthritis, we show here in which extent models were invaluable to enlighten different mechanisms such as the role of innate immunity, T and B cells, vessels, or microbiota. Moreover, models were the starting point of in vivo application of cytokine-blocking strategies such as anti-TNF or anti-IL-6 treatments. The most popular models are the different types of collagen-induced arthritis and arthritis in KBN mice. As spontaneous arthritides, human TNF-α transgenic mice are a reliable model. It is mandatory to use animal models in the respect of ethical procedure, particularly regarding the number of animals and the control of pain. Moreover, design of experiments should be of the highest level, animal models of arthritis being dedicated to exploration of well-based novelties, and never used for confirmation or replication of already proven concepts. The best interpretations of data in animal models of arthritis suppose integrated research, including translational studies from animals to humans.

Ex vivo all-trans retinoic acid modulates NO production and regulates IL-6 effect during rheumatoid arthritis: a study in Algerian patients

Rheumatoid arthritis (RA) is a chronic autoimmune disease. The pathophysiology of RA implicates several mediators such as nitric oxide (NO) and cytokines such as interleukin-6 (IL-6), which is deeply involved in the main characteristics of RA. Furthermore, all-trans retinoic acid (ATRA) is an active vitamin A derivative well-known to have diverse immunomodulatory actions. In our study, we investigated first, the ex vivo immunomodulatory potential of ATRA on NO pathway by peripheral blood mononuclear cells (PBMCs) from Algerian RA patients. Then, we assessed the possible regulatory effect of ATRA on NO production induced by IL-6. PBMCs isolated from active and inactive RA patients and healthy controls were cultured with different concentrations of IL-6 or/with ATRA. NO production was assessed using the Griess method. Inducible nitric oxide synthase expression and NF-κB activity were analyzed by immunofluorescence test. Our results revealed a high NO production during active RA. We noticed that while IL-6 induced a high NO production and iNOS expression, ATRA downregulated both. ATRA also inhibited nuclear NF-κB translocation. Interestingly, it seems that NO production mediated by IL-6 on PBMCs of RA patients is downregulated by ATRA. Taken together, our results highlight the immunomodulatory effect of ATRA on NO pathway in RA patients and its possible role in regulating IL-6-mediated NO production. All these findings suggest its potential therapeutic role during RA.

Calprotectin (S100A8/A9) has the strongest association with ultrasound-detected synovitis and predicts response to biologic treatment: results from a longitudinal study of patients with established rheumatoid arthritis

BACKGROUND

Calprotectin (S100A8/A9 or MRP8/14) and S100A12 (leukocyte-derived proteins), interleukin 6 (IL-6) and vascular endothelial growth factor (VEGF) are markers of inflammation and angiogenesis. Ultrasound (US) is sensitive for detection of greyscale synovitis and power Doppler (PD) vascularization. The objective of the present study was to explore the associations between calprotectin, S100A12, IL-6, VEGF, erythrocyte sedimentation rate, C-reactive protein and a comprehensive US assessment in patients with rheumatoid arthritis (RA) starting biologic disease-modifying anti-rheumatic drug (bDMARD) treatment.

METHODS

A total of 141 patients with RA were assessed by US, clinical examination and biomarker levels at baseline and at 1, 2, 3, 6 and 12 months after initiation of bDMARDs. US assessment of 36 joints and 4 tendon sheaths were scored semi-quantitatively (0-3 scale). European League Against Rheumatism (EULAR) response was calculated. Statistical assessments performed to explore the associations between biomarkers and US sum scores included Spearman's rank correlation analysis as well as linear and linear mixed model regression analyses.

RESULTS

Calprotectin showed the overall strongest correlations with both US sum scores (r _s = 0.25-0.62) and swollen joint counts (of 32) (r _s = 0.24-0.47) (p < 0.05 at all examinations). An association with US sum scores remained after we adjusted for age, sex, disease duration and all the other markers in a regression analysis at baseline. Decreased calprotectin at the first month was predictive of both EULAR response (p ≤ 0.001) and decreased sum PD scores at 3, 6 and 12 months (p ≤ 0.05).

CONCLUSIONS

Calprotectin had the highest association with US synovitis and predicted treatment response. It may thus be considered as a marker for evaluating inflammation and responsiveness in patients with RA on bDMARD treatment.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry (ANZCTR) identifier: ACTRN12610000284066 . Registered on 8 April 2010 (retrospectively registered).

Relationship between VEGF Gene Polymorphisms and Serum VEGF Protein Levels in Patients with Rheumatoid Arthritis

BACKGROUND

Rheumatoid arthritis (RA) is one of the chronic autoimmune diseases, with genetic and environmental predisposition, and synovial angiogenesis is considered to be a notable stage in its pathogenesis. Angiogenesis or vascular proliferation has been suggested to be a pivotal mechanism involved in both inflammation/immune activation and joint invasion and destruction. RA may be considered an "angiogenic disease" because it is associated with active tissue neovascularization. Vascular endothelial growth factor (VEGF) promotes vascular permeability, regulates angiogenesis, endothelial cell proliferation and migration, chemotaxis, and capillary hyper permeability and therefore is involved in the development of inflammation. VEGF is the most potent proangiogenic molecule promoting the angiogenic phenotype of RA and is upregulated in RA.

OBJECTIVES

The aim of the study was to identify functional VEGF variants and their possible association with VEGF expression, susceptibility to and severity of RA.

METHODS

581 RA patients and of 341 healthy individuals were examined for -1154 A/G, -2578 A/C VEGF gene polymorphisms by PCR-RFLP method and for -634 G/C VEGF gene polymorphisms by TaqMan SNP genotyping assay. Serum VEGF levels in RA patients and controls were measured by ELISA.

RESULTS

The -1154 A/G VEGF gene polymorphism under the codominant, recessive (AA+AG vs. GG) and dominant (AA vs. AG+GG) models were associated with RA (p = 0.0009; p = 0.004; p = 0.017, respectively). VEGF -2578 A/C revealed differences in the case-control distribution in codominant, recessive, dominant and overdominant models (all p<0.0001). Furthermore, the -634 G/C VEGF gene SNP was not correlated with susceptibility to RA in Polish population. The genotype-phenotype analysis showed significant association between the VEGF -1154 A/G and -634 G/C and mean value of the hemoglobin (all p = 0.05), additionally they relevated that the number of women with the polymorphic allele -2578 C was lower than the number of women with wild type allele -2578A (p = 0.006). Serum VEGF levels were significantly higher in RA patients than in control groups (both p = 0,0001).

CONCLUSION

Present findings indicated that VEGF genetic polymorphism as well as VEGF protein levels may be associated with the susceptibility to RA in the Polish population.

Anti-angiogenic effect of total saponins of Rhizoma Dioscorea nipponica on collagen induced-arthritis in rats

Rheumatoid arthritis (RA) is a common chronic autoimmune and incurable disease. The aim of the present study was to investigate the therapeutic effect and mechanism of the total saponins of Rhizoma Dioscorea nipponica (TSRDN) in RA. A collagen induced-arthritis (CIA) rat model was established. CIA rats were randomly divided into three groups and lavaged with an equal volume of solvent (CIA group), TSRDN (25 mg/kg/day, RDN group) and tripterygium (TP; 12 mg/kg/day, TP group) for 21 days, respectively. Normal rats served as a control group. Hematoxylin-eosin (HE) staining was used to observe the histopathological injury of synovial tissues. The level of CD31, which used for marking and counting, micro vessel density (MVD) and the expression levels of vascular endothelial growth factor (VEGF) and signal transducer and activator of transcription 3 (STAT3) were detected by immunohistochemical analysis. Additionally, the DNA-binding activity of nuclear factor-κB (NF-κB) was determined using an ELISA kit. HE staining showed obvious synovial hyperplasia, inflammatory cell infiltration, pannus formation, cartilage and bone erosion in the CIA group rats. In addition, compared with control group, the level of MVD, the expression of VEGF and STAT3, and the DNA-binding activity of NF-κB were all increased in CIA group rat synovial tissue (all P<0.01); however, TSRDN or tripterygium were able to inhibit these changes (all P<0.01). It was speculated that TSRDN may prevent angiogenesis by inhibiting the expression of STAT3 and the DNA-binding activity of NF-κB p65, thereby potentially improving CIA.

Anti-inflammatory effects of oroxylin A on RAW 264.7 mouse macrophages induced with polyinosinic-polycytidylic acid

Oroxylin A (5,7-dihydroxy-6-methoxy-2-phenylchromen-4-one; Baicalein 6-methyl ether) is an active flavonoid compound originally isolated from Scutellaria radix, which has been used to treat pulmonary infection in Korea, China, and Japan. Oroxylin A is known to possess dopamine reuptake inhibitor activity. However, the effects of oroxylin A on virus-induced macrophages has not been fully elucidated. In the present study, the anti-inflammatory effects of oroxylin A on double-stranded RNA-induced macrophages were examined. Production of nitric oxide (NO), various cytokines, as well as calcium release and the mRNA expression of signal transducer and activator of transcription 1 (STAT1) in dsRNA polyinosinic-polycytidylic acid (PIC)-induced RAW 264.7 mouse macrophages were evaluated. Oroxylin A restored the cell viability in PIC-induced RAW 264.7 mouse macrophages at concentrations of up to 50 µM. Additionally, oroxylin A significantly inhibited the production of nitric oxide (NO), interleukin (IL)-1α, IL-1β, IL-6, IL-10, interferon gamma-induced protein 10, granulocyte-colony stimulating factor (CSF), granulocyte macrophage-CSF, leukemia inhibitory factor (IL-6 class cytokine), lipopolysaccharide-induced CXC chemokine (LIX), monocyte chemoattractant protein 1, macrophage inflammatory protein (MIP)-1α, MIP-1β, MIP-2, Regulated on Activation, Normal T Expressed and Secreted, tumor necrosis factor-α, and vascular endothelial growth factor as well as calcium release and the mRNA expression of STAT1 in PIC-induced RAW 264.7 cells (P<0.05). Thus, the present results suggest that oroxylin A has anti-inflammatory properties, associated with its inhibition of NO, cytokines, chemokines and growth factors in PIC-induced macrophages via the calcium-STAT pathway.

Targeting VEGF and Its Receptors for the Treatment of Osteoarthritis and Associated Pain

Increased vascular endothelial growth factor (VEGF) levels are associated with osteoarthritis (OA) progression. Indeed, VEGF appears to be involved in OA-specific pathologies including cartilage degeneration, osteophyte formation, subchondral bone cysts and sclerosis, synovitis, and pain. Moreover, a wide range of studies suggest that inhibition of VEGF signaling reduces OA progression. This review highlights both the potential significance of VEGF in OA pathology and pain, as well as potential benefits of inhibition of VEGF and its receptors as an OA treatment. With the emergence of the clinical use of anti-VEGF therapy outside of OA, both as high-dose systemic treatments and low-dose local treatments, these particular therapies are now more widely understood. Currently, there is no established disease-modifying drug available for patients with OA, which warrants continued study of the inhibition of VEGF signaling in OA, as stand-alone or adjuvant therapy. © 2016 American Society for Bone and Mineral Research.

Clinical effects of tocilizumab on cytokines and immunological factors in patients with rheumatoid arthritis

Interleukin (IL)-6 is one of the crucial proinflammatory cytokines. The dysregulation of IL-6 plays a pivotal role in rheumatoid arthritis (RA) and is involved in several of the common clinical manifestations associated with active RA. Recent therapies targeting IL-6 and tumor necrosis factor (TNF) have resulted in clinical improvements in signs and symptoms, disability and quality of life in patients with early and long-standing RA. Because it has been demonstrated that cytokines and inflammatory/immunological factors appear to be important and sensitive mediators in RA patients treated with tocilizumab and with anti-TNF biologics, it is important to investigate whether tocilizumab administration has any effect(s) on the profiles of cytokines and inflammatory/immunological factors and whether these changes correlate with the clinical improvement in RA disease activity. In this review, we discuss the effects on cytokine regulation and the differentiation of immune cells, especially T cells, after tocilizumab therapy in patients with RA.

Six Novel Loci Associated with Circulating VEGF Levels Identified by a Meta-analysis of Genome-Wide Association Studies

Vascular endothelial growth factor (VEGF) is an angiogenic and neurotrophic factor, secreted by endothelial cells, known to impact various physiological and disease processes from cancer to cardiovascular disease and to be pharmacologically modifiable. We sought to identify novel loci associated with circulating VEGF levels through a genome-wide association meta-analysis combining data from European-ancestry individuals and using a dense variant map from 1000 genomes imputation panel. Six discovery cohorts including 13,312 samples were analyzed, followed by in-silico and de-novo replication studies including an additional 2,800 individuals. A total of 10 genome-wide significant variants were identified at 7 loci. Four were novel loci (5q14.3, 10q21.3, 16q24.2 and 18q22.3) and the leading variants at these loci were rs114694170 (MEF2C, P = 6.79x10^-13), rs74506613 (JMJD1C, P = 1.17x10^-19), rs4782371 (ZFPM1, P = 1.59x10^-9) and rs2639990 (ZADH2, P = 1.72x10^-8), respectively. We also identified two new independent variants (rs34528081, VEGFA, P = 1.52x10^-18; rs7043199, VLDLR-AS1, P = 5.12x10^-14) at the 3 previously identified loci and strengthened the evidence for the four previously identified SNPs (rs6921438, LOC100132354, P = 7.39x10^-1467; rs1740073, C6orf223, P = 2.34x10^-17; rs6993770, ZFPM2, P = 2.44x10^-60; rs2375981, KCNV2, P = 1.48x10^-100). These variants collectively explained up to 52% of the VEGF phenotypic variance. We explored biological links between genes in the associated loci using Ingenuity Pathway Analysis that emphasized their roles in embryonic development and function. Gene set enrichment analysis identified the ERK5 pathway as enriched in genes containing VEGF associated variants. eQTL analysis showed, in three of the identified regions, variants acting as both cis and trans eQTLs for multiple genes. Most of these genes, as well as some of those in the associated loci, were involved in platelet biogenesis and functionality, suggesting the importance of this process in regulation of VEGF levels. This work also provided new insights into the involvement of genes implicated in various angiogenesis related pathologies in determining circulating VEGF levels. The understanding of the molecular mechanisms by which the identified genes affect circulating VEGF levels could be important in the development of novel VEGF-related therapies for such diseases.

Vascular Endothelial Growth Factor (VEGF) is a protein with a fundamental role in development of vascular system. The protein, produced by many types of cells, is released in the blood. High levels of VEGF have been observed in different pathological conditions especially in cancer, cardiovascular, and inflammatory diseases. Therefore, identifying the genetic factors influencing VEGF levels is important for predicting and treating such pathologies. The number of genetic variants associated with VEGF levels has been limited. To identify new loci, we have performed a Genome Wide Association Study meta-analysis on a sample of more than 16,000 individuals from 10 cohorts, using a high-density genetic map. This analysis revealed 10 variants associated with VEGF circulating levels, 6 of these being novel associations. The 10 variants cumulatively explain more than 50% of the variability of VEGF serum levels. Our analyses have identified genes known to be involved in angiogenesis related diseases and genes implicated in platelet metabolism, suggesting the importance of links between this process and VEGF regulation. Overall, these data have improved our understanding of the genetic variation underlying circulating VEGF levels. This in turn could guide our response to the challenge posed by various VEGF-related pathologies.

Serum Markers in Rheumatoid Arthritis: A Longitudinal Study of Patients Undergoing Infliximab Treatment

Objective. The aim of this study was to investigate the clinical effect and serum markers in a cohort of rheumatoid arthritis patients with moderate to high disease activity, participating in an open clinical phase IV study conducted in Norway between 2001 and 2003 receiving infliximab treatment. Method. A total of 39 patients were studied, with a mean age of 54 years and 12-year disease duration. The analyses were performed using serum from patients at four assessment time points: baseline and 3, 6, and 12 months after starting treatment with infliximab. A wide variety of clinical data was collected and disease activity of 28 joints and Simple Disease Activity Index were calculated. The joint erosion was determined by X-ray imaging and the Sharp/van der Heijde score was determined. Serum analysis included multiplex immunoassays for 12 cytokines, 5 matrix metalloproteases, and 2 VEGFs. Results. The majority of the RA patients in this study had initially moderate to high disease activity and the infliximab treatment reduced the disease activity significantly and also reduced any further joint destruction and improved disease status. Most of the serum levels of cytokines and metalloproteases remained unchanged during the course of the study, and we were unable to detect changes in TNF-α in serum. Serum levels of IL-6 and VEGF-A decreased significantly after initiation of infliximab treatment. Conclusion. The serum levels of IL-6 and VEGF-A may be promising disease markers as they vary with disease progression. The clinical significance of these findings is yet to be determined and has to be confirmed in future clinical trials before being applied in the clinics.

Hypoxic regulation of osteoclast differentiation and bone resorption activity

Bone integrity is maintained throughout life via the homeostatic actions of bone cells, namely, osteoclasts, which resorb bone, and osteoblasts, which produce bone. Disruption of this balance in favor of osteoclast activation results in pathological bone loss, which occurs in conditions including osteoporosis, rheumatoid arthritis, primary bone cancer, and cancer metastasis to bone. Hypoxia also plays a major role in these conditions, where it is associated with disease progression and poor prognosis. In recent years, considerable interest has arisen in the mechanisms whereby hypoxia and the hypoxia-inducible transcription factors, HIF-1α and HIF-2α, affect bone remodeling and bone pathologies. This review summarizes the current evidence for hypoxia-mediated regulation of osteoclast differentiation and bone resorption activity. Role(s) of HIF and HIF target genes in the formation of multinucleated osteoclasts from cells of the monocyte-macrophage lineage and in the activation of bone resorption by mature osteoclasts will be discussed. Specific attention will be paid to hypoxic metabolism and generation of ATP by osteoclasts. Hypoxia-driven increases in both glycolytic flux and mitochondrial metabolic activity, along with consequent generation of mitochondrial reactive oxygen species, have been found to be essential for osteoclast formation and resorption activity. Finally, evidence for the use of HIF inhibitors as potential therapeutic agents targeting bone resorption in osteolytic disease will be discussed.