Blockage of the formation of new blood vessels by recombinant human endostatin contributes to the regression of rat adjuvant arthritis

Bioink with cartilage-derived extracellular matrix microfibers enables spatial control of vascular capillary formation in bioprinted constructs

Microvasculature is essential for the exchange of gas and nutrient for most tissues in our body. Some tissue structures such as the meniscus presents spatially confined blood vessels adjacent to non-vascularized regions. In biofabrication, mimicking the spatial distribution of such vascular components is paramount, as capillary ingrowth into non-vascularized tissues can lead to tissue matrix alterations and subsequent pathology. Multi-material 3D bioprinting can potentially resolve anisotropic tissue features, although building complex constructs comprising stable vascularized and non-vascularized regions remains a major challenge. Here, we developed endothelial cell(EC)-laden pro- and anti-angiogenic bioinks, supplemented with bioactive matrix-derived microfibers (MFs) that were created from type I collagen sponges (col-1) and cartilage decellularized extracellular matrix (CdECM). EC-driven capillary network formation started two days after bioprinting. Supplementing cartilage-derived MFs to endothelial-cell laden bioinks reduced the total length of neo-microvessels by 29% after 14 days, compared to col-1 MFs-laden bioinks. As a proof of concept, the bioinks were bioprinted into an anatomical meniscus shape with a biomimetic vascularized outer and non-vascularized inner region, using a microgel suspension bath. The constructs were cultured up to 14 days, with in the outer zone the HUVEC-, mural cell-, and col-1 MF-laden pro-angiogenic bioink, and in the inner zone a meniscus progenitor cell (MPC)- and CdECM MF-laden anti-angiogenic bioink, revealing successful spatial confinement of the nascent vascular network only in the outer zone. Further, to co-facilitate both microvessel formation and MPC-derived matrix formation, we formulated cell culture medium conditions with a temporal switch. Overall, this study provides a new strategy that could be applied to develop zonal biomimetic meniscal constructs. Moreover, the use of ECM-derived MFs to promote or inhibit capillary networks opens new possibilities for the biofabrication of tissues with anisotropic microvascular distribution. These have potential for many applications including in vitro models, cancer progression, and testing anti-angiogenic therapies.

Acidosis induces synovial fibroblasts to release vascular endothelial growth factor via acid-sensitive ion channel 1a

Acid-sensitive ion channel 1a (ASIC1a) is a member of the extracellular H+ activated cation channel family. Studies have shown that tissue acidification contributes to the formation of microvessels in rheumatoid arthritis (RA) synovial tissue, but its underlying mechanisms remain unclear. The purpose of this study was to investigate the role of tissue acidification in microvascular formation of arthritic synovial tissue and the effect of ASIC1a on vascular endothelial growth factor (VEGF) release from arthritic synovial tissue. Our results indicate that ASIC1a expression, VEGF expression, and microvessel density (MVD) are elevated in RA synovial tissue and adjuvant arthritis (AA) rat synovial tissue. When AA rats were treated with ASIC1a-specific blocker psalmotoxin-1 (PcTx-1), the expression of ASIC1a, VEGF expression, and MVD were all reduced. Acidification of RA synovial fibroblasts (RASF) can promote the release of VEGF. PcTx-1 and ASIC1a-short hairpin RNA can inhibit acid-induced release of VEGF. In addition, the ASIC1a overexpression vector can promote acid-induced VEGF release. This indicates that extracellular acidification induces the release of VEGF by RASF via ASIC1a. These findings suggest that blocking ASIC1a mediates the release of VEGF from synoviocytes may provide a potential therapeutic strategy for RA therapy.

The Tumor-Like Phenotype of Rheumatoid Synovium: Molecular Profiling and Prospects for Precision Medicine

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by destructive hyperplasia of the synovium. Fibroblast-like synoviocytes (FLS) are a major component of synovial pannus and actively participate in the pathologic progression of RA. How rheumatoid FLS acquire and sustain such a uniquely aggressive phenotype remains poorly understood. We describe the current state of knowledge of the molecular alterations in rheumatoid FLS at the genomic, epigenomic, transcriptomic, proteomic, and metabolomic levels, which offers a means to reconstruct the pathways leading to rheumatoid pannus. Such data provide new pathologic insight and suggest means to more sensitively assess disease activity and response to therapy, as well as support new avenues for therapeutic development.

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.

Recombinant human endostatin inhibits TNF-alpha-induced receptor activator of NF-κB ligand expression in fibroblast-like synoviocytes in mice with adjuvant arthritis

Bone loss is a critical pathology responsible for the functional disability in patients with rheumatoid arthritis (RA). It is well known that receptor activator of nuclear factor kappa-B (NF-κB) ligand (RANKL) plays a crucial role in bone loss in RA. The purpose of this study was to determine whether recombinant human endostatin (rh-endostatin) mediates bone erosion in RA by regulation of RANKL expression in an experimental model of RA, consisting of mice with adjuvant-induced arthritis (AA). Cultured AA fibroblast-like synoviocytes (FLSs) obtained from these mice were induced by tumor necrosis factor-α (TNF-α) combined with or without rh-endostatin. The levels of RANKL and osteoprotegerin (OPG) mRNA, soluble and membrane-bound proteins were assessed by real-time PCR, ELISA, and Western blotting. Western blotting and the luciferase reporter assay were used to study related signaling pathways. Rh-endostatin inhibited RANKL mRNA expression, soluble and membrane-bound protein expression in AA FLSs but not in CD4+ T cells. However, OPG expression and secretion was not affected by rh-endostatin in AA FLSs. Molecular analysis demonstrated that rh-endostatin significantly inhibited TNF-α-induced MAPK and AP-1 signaling pathways. Moreover, rh-endostatin attenuated TNF-α-induced NF-κB signaling by suppressing the phosphorylation level of inhibitor kappaBα (IκBα) and nuclear translocation of NF-κB p65 in FLSs from mice with AA. These results provide the first evidence that rh-endostatin inhibits TNF-α-induced RANKL expression in AA FLSs.

Recombinant Human Endostatin Suppresses Mouse Osteoclast Formation by Inhibiting the NF-κB and MAPKs Signaling Pathways

Rheumatoid arthritis is an autoimmune disease characterized by synovial hyperplasia and progressive joint destruction. As reported previously, recombinant human endostatin (rhEndostatin) is associated with inhibition of joint bone destruction present in rat adjuvant-induced arthritis; however, the effect of rhEndostatin on bone destruction is not known. This study was designed to assess the inhibitory effect and mechanisms of rhEndostatin on formation and function of osteoclasts in vitro, and to gain insight into the mechanism underlying the inhibitory effect of bone destruction. Bone marrow-derived macrophages isolated from BALB/c mice were stimulated with receptor activator of NF-κB ligand (RANKL) and macrophage colony-stimulating factor to establish osteoclast formation. Osteoclast formation was determined by TRAP staining. Cell viability of BMMs affected by rhEndostatin was determined using a MTT assay. Bone resorption was examined with a bone resorption pits assay. The expression of osteoclast-specific markers was analyzed using quantitative real-time PCR. The related signaling pathways were examined using a Luciferase reporter assay and western blot analysis. Indeed, rhEndostatin showed a significant reduction in the number of osteoclast-like cells and early-stage bone resorption. Moreover, molecular analysis demonstrated that rhEndostatin attenuated RANKL-induced NF-κB signaling by inhibiting the phosphorylation of IκBα and NF-κB p65 nuclear translocation. Furthermore, rhEndostatin significantly inhibited the activation of RANKL-dependent mitogen-activated protein kinases, such as ERK1/2, JNK, and p38. Hence, we demonstrated for the first time that preventing the formation and function of osteoclasts is an important anti-bone destruction mechanism of rhEndostatin, which might be useful in the prevention and treatment of bone destruction in RA.

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.

The potential role of angiogenic factors in rheumatoid arthritis

Angiogenesis is an important phenomenon in the pathogenesis of some diseases, such as numerous types of tumors and autoimmunity, and also a number of soluble and cell-bound factors may stimulate neovascularization in inflammatory reaction processes. Here, by highlighting the significance of angiogenesis reaction in rheumatoid arthritis (RA), we will mainly focus on the role of various growth factors, cytokines, enzymes, cells, hypoxic conditions and transcription factors in the angiogenic process and we will then explain some therapeutic strategies based on blockage of angiogenesis and modification of the vascular pathology in RA.

Putative effects of potentially anti-angiogenic drugs in rheumatic diseases

A role for angiogenesis has been described in several rheumatic diseases, including rheumatoid arthritis, psoriatic arthritis, ankylosing spondylitis, systemic sclerosis, systemic lupus erythematosus, vasculitides, and osteoarthritis, leading to the possibility that angiogenesis inhibition may be an additional useful therapeutic arm. While the role of anti-angiogenic therapy in rheumatoid arthritis has received attention, it is conceivable that the inhibition of pathological angiogenesis may also be a useful therapeutical approach in other rheumatic diseases. Numerous compounds, such as, for example, various interleukins, antibodies directed against angiogenic factors, peptides, estrogen metabolites, disease-modifying anti-rheumatic drugs, have been found to have anti-angiogenic properties. However, additional research is needed to obtain a clear understanding of the pathogenic mechanism of angiogenesis and the potential applications of anti-angiogenic therapy in rheumatic diseases.

Blood vessels, a potential therapeutic target in rheumatoid arthritis?

New micro-vessels formation within synovium and macro-vessels endothelial damage with atheroma are two major features of rheumatoid arthritis, the former related to the articular involvement of the disease, the latter to its main systemic complication. The similarities between pannus development and solid tumors growth, and the efficacy of anti-angiogenic treatments in oncology, opened the perspective of directly targeting angiogenesis in arthritis. Nevertheless, despite the success of different anti-angiogenic therapeutic strategies in many arthritis experimental models, the application in human disease is still lacking. Recent data suggest that synovial neoangiogenesis and macro-vessels endothelial damage might be two linked phenomena. While synovial angiogenesis seems to be detrimental to endothelial damage repair, even anti-angiogenic treatments might paradoxically aggravate macro-vascular disease, especially in the context of uncontrolled inflammation. These elements induce to further explore the interconnections between inflammation and angiogenesis on one side and between micro- and macro-vascular diseases on the other, in order to establish the proper way to therapeutically target blood vessels in rheumatoid arthritis.

Angiogenesis in rheumatoid arthritis

Angiogenesis is the formation of new capillaries from pre-existing vessels. A number of soluble and cell-bound factors may stimulate neovascularization. The perpetuation of angiogenesis involving numerous soluble and cell surface-bound mediators has been associated with rheumatoid arthritis (RA). These angiogenic mediators, among others, include growth factors, primarily vascular endothelial growth factor (VEGF) and hypoxia-inducible factors (HIFs), as well as pro-inflammatory cytokines, various chemokines, matrix components, cell adhesion molecules, proteases and others. Among the several potential angiogenesis inhibitors, targeting of VEGF, HIF-1, angiogenic chemokines, tumor necrosis factor-alpha and the alpha(V)beta(3) integrin may attenuate the action of angiogenic mediators and thus synovial angiogenesis. In addition, some naturally produced or synthetic compounds including angiostatin, endostatin, paclitaxel, fumagillin analogues, 2-methoxyestradiol and thalidomide may be included in the management of RA.

Angiogenesis and its targeting in rheumatoid arthritis

Angiogenesis, the development of new capillaries, is involved in leukocyte ingress into the synovium during the development and progression of rheumatoid arthritis. Several soluble and cell surface-bound mediators including growth factors, cytokines, chemokines, proteolytic matrix-degrading enzymes, cell adhesion molecules and others may promote synovial neovascularization. On the other hand, endogenous angiostatic factors, such as angiostatin, endostatin, interleukin-4 (IL-4), IL-13, interferons and some angiostatic chemokines are also produced within the rheumatoid synovium, however, their effects are insufficient to control synovial angiogenesis and inflammation. Several specific and non-specific strategies have been developed to block the action of angiogenic mediators. The first line of angiostatic agents include vascular endothelial growth factor (VEGF), angiopoietin, alpha(V)beta(3) integrin antagonist, as well as non-specific angiogenesis inhibitors including traditional disease-modifying agents (DMARDs), anti-tumor necrosis factor biologics, angiostatin, endostatin, fumagillin analogues or thalidomide. Potentially any angiostatic compound could be introduced to studies using animal models of arthritis or even to human rheumatoid arthritis trials.

Angiogenesis as a therapeutic target in arthritis: learning the lessons of the colorectal cancer experience

The idea of a therapeutic modality aimed at 'starving' a tissue of blood vessels, and consequentially of oxygen and nutrients, was born from the concept that blood vessel formation (angiogenesis) is central to the progression and maintenance of diseases which involve tissue expansion/invasion. In the first instance, solid malignancies were the target for anti-angiogenic treatments, with colorectal cancer being the first disease for which an angiogenesis inhibitor--anti-vascular endothelial growth factor antibody bevacizumab--was approved in 2004. Our understanding of the pathogenesis of rheumatoid arthritis (RA) has lead to many parallels being drawn between this chronic inflammatory disease and solid tumours, in that both involve tissue expansion, invasion, expression of cytokines and growth factors and areas of hypoxia/hypoperfusion. As a result, angiogenesis blockade has been touted as a possible treatment for RA. The lessons learnt during the progression of eventually successful therapies such as bevacizumab should undoubtedly guide us in the future development of comparable treatments for RA.

Effect of (S)-4-(1-(5-chloro-2-(4-fluorophenyoxy)benzamido)ethyl) benzoic acid (CJ-42794), a selective antagonist of prostaglandin E receptor subtype 4, on ulcerogenic and healing responses in rat gastrointestinal mucosa

Recent research showed the involvement of prostaglandin E receptor subtype 4 (EP4) in hypersensitivity to inflammatory pain and suggested that the EP4 receptor is a potential target for the pharmacological treatment of inflammatory pain. We examined the effects of (S)-4-(1-(5-chloro-2-(4-fluorophenyoxy) benzamido)ethyl) benzoic acid (CJ-42794), a selective EP4 antagonist, on gastrointestinal ulcerogenic and healing responses in rats, in comparison with those of various cyclooxygenase (COX) inhibitors. CJ-42794 alone, given p.o., did not produce any damage in the gastrointestinal mucosa, similar to 5-(4-chlorophenyl)-1-(4-methoxyphenyl)-3-(trifluoromethyl)-1H-pyrazole (SC-560) (COX-1 inhibitor) or rofecoxib (COX-2 inhibitor), whereas indomethacin (nonselective COX inhibitor) caused gross lesions. Rofecoxib but not CJ-42794, however, damaged these tissues when coadministered with SC-560 and aggravated gastric lesions produced by aspirin. Indomethacin and SC-560 worsened the gastric ulcerogenic response to cold-restraint stress, yet neither CJ-42794 nor rofecoxib had any effect. Furthermore, indomethacin and SC-560 at lower doses damaged the stomach and small intestine of adjuvant arthritic rats. In arthritic rats, rofecoxib but not CJ-42794 provoked gastric ulceration, whereas CJ-42794 produced little damage in the small intestine. The repeated administration of CJ-42794 and rofecoxib as well as indomethacin impaired the healing of chronic gastric ulcers with a down-regulation of vascular endothelial growth factor expression in the ulcerated mucosa. These results suggest that CJ-42794 does not cause any damage in the normal rat gastrointestinal mucosa and in the arthritic rat stomach and does not worsen the gastric ulcerogenic response to stress or aspirin in normal rats, although this agent slightly damages the small intestine of arthritic rats and impairs the healing of gastric ulcers.