siRNA-based therapeutic approaches for rheumatic diseases

Administration of Liposomal-Based Pde3b Gene Therapy Protects Mice Against Collagen-Induced Rheumatoid Arthritis via Modulating Macrophage Polarization

Background

Rheumatoid arthritis (RA) is a chronic and systemic autoimmune disease characterized by synovial inflammation and joint destruction. Despite progress in RA therapy, it remains difficult to achieve long-term remission in RA patients. Phosphodiesterase 3B (Pde3b) is a member of the phosphohydrolyase family that are involved in many signal transduction pathways. However, its role in RA is yet to be fully addressed.

Methods

Studies were conducted in arthritic DBA/1 mice, a suitable mouse strain for collagen-induced rheumatoid arthritis (CIA), to dissect the role of Pde3b in RA pathogenesis. Next, RNAi-based therapy with Pde3b siRNA-loaded liposomes was assessed in a CIA model. To study the mechanism involved, we investigated the effect of Pde3b knockdown on macrophage polarization and related signaling pathway.

Results

We demonstrated that mice with CIA exhibited upregulated Pde3b expression in macrophages. Notably, intravenous administration of liposomes loaded with Pde3b siRNA promoted the macrophage anti-inflammatory program and alleviated CIA in mice, as indicated by the reduced inflammatory response, synoviocyte infiltration, and bone and cartilage erosion. Mechanistic study revealed that depletion of Pde3b increased cAMP levels, by which it enhanced PKA-CREB-C/EBPβ pathway to transcribe the expression of anti-inflammatory program-related genes.

Conclusion

Our results support that Pde3b is involved in the pathogenesis of RA, and Pde3b siRNA-loaded liposomes might serve as a promising therapeutic approach against RA.

Pulmonary siRNA Delivery with Sophisticated Amphiphilic Poly(Spermine Acrylamides) for the Treatment of Lung Fibrosis

RNA interference (RNAi) is an efficient strategy to post-transcriptionally silence gene expression. While all siRNA drugs on the market target the liver, the lung offers a variety of currently undruggable targets, which can potentially be treated with RNA therapeutics. To achieve this goal, the synthesis of poly(spermine acrylamides) (P(SpAA) is reported herein. Polymers are prepared via polymerization of N-acryloxysuccinimide (NAS) and afterward this active ester is converted into spermine-based pendant groups. Copolymerizations with decylacrylamide are employed to increase the hydrophobicity of the polymers. After deprotection, polymers show excellent siRNA encapsulation to obtain perfectly sized polyplexes at very low polymer/RNA ratios. In vitro 2D and 3D cell culture, ex vivo and in vivo experiments reveal superior properties of amphiphilic spermine-copolymers with respect to delivery of siRNA to lung cells in comparison to commonly used lipid-based transfection agents. In line with the in vitro results, siRNA delivery to human lung explants confirm more efficient gene silencing of protease-activated receptor 2 (PAR2), a G protein-coupled receptor involved in fibrosis. This study reveals the importance of the balance between efficient polyplex formation, cellular uptake, gene knockdown, and toxicity for efficient siRNA delivery in vitro, in vivo, and in fibrotic human lung tissue ex vivo.

Inhibition of the MALT1-LPCAT3 axis protects cartilage degeneration and osteoarthritis

The proinflammatory cytokines and arachidonic acid (AA)-derived eicosanoids play a key role in cartilage degeneration in osteoarthritis (OA). The lysophosphatidylcholine acyltransferase 3 (LPCAT3) preferentially incorporates AA into the membranes. Our recent studies showed that MALT1 [mucosa-associated lymphoid tissue lymphoma translocation protein 1]) plays a crucial role in propagating inflammatory signaling triggered by IL-1β and other inflammatory mediators in endothelial cells. The present study shows that LPCAT3 expression was up-regulated in both human and mice articular cartilage of OA, and correlated with severity of OA. The IL-1β-induces cell death via upregulation of LPCAT3, MMP3, ADAMTS5, and eicosanoids via MALT1. Gene silencing or pharmacological inhibition of LPCAT3 or MALT1 in chondrocytes and human cartilage explants notably suppressed the IL-1β-induced cartilage catabolism through inhibition of expression of MMP3, ADAMTS5, and also secretion of cytokines and eicosanoids. Mechanistically, overexpression of MALT1 in chondrocytes significantly upregulated the expression of LPCAT3 along with MMP3 and ADAMTS5 via c-Myc. Inhibition of c-Myc suppressed the IL-1β-MALT1-dependent upregulation of LPCAT3, MMP3 and ADAMTS5. Consistent with the in vitro data, pharmacological inhibition of MALT1 or gene silencing of LPCAT3 using siRNA-lipid nanoparticles suppressed the synovial articular cartilage erosion, pro-inflammatory cytokines, and eicosanoids such as PGE2, LTB4, and attenuated osteoarthritis induced by the destabilization of the medial meniscus in mice. Overall, our data reveal a previously unrecognized role of the MALT1-LPCAT3 axis in osteoarthritis. Targeting the MALT1-LPCAT3 pathway with MALT1 inhibitors or siRNA-liposomes of LPCAT3 may become an effective strategy to treat OA by suppressing eicosanoids, matrix-degrading enzymes, and proinflammatory cytokines.

Overcoming delivery barriers for RNA therapeutics in the treatment of rheumatoid arthritis

RNA therapeutics can manipulate gene expression or protein production, making them suitable for treating a wide range of diseases. Theoretically, any disease that has a definite biological target would probably find feasible therapeutic approach from RNA-based therapeutics. Numerous clinical trials using RNA therapeutics fighting against cancer, infectious diseases or inherited diseases have been reported and achieved desirable therapeutic efficacy. So far, encouraging findings from various animal experimental studies have also confirmed the great potential of RNA-based therapies in the treatment of rheumatic arthritis (RA). However, the in vivo multiple physiological barriers still seriously compromise the therapeutic efficacy of RNA drugs. Thus, safe and effective delivery strategies for RNA therapeutics are quite essential for their further and wide application in RA therapy. In this review, we will discuss the recent progress achieved using RNA-based therapeutics and focus on delivery strategies that can overcome the in vivo delivery barriers in RA treatment. Furthermore, discussion about the existing problems in current RNA delivery systems for RA therapy has been also included here.

Emergence of Small Interfering RNA-Based Gene Drugs for Various Diseases

Small molecule, peptide, and protein-based drugs have been developed over decades to treat various diseases. The importance of gene therapy as an alternative to traditional drugs has increased after the discovery of gene-based drugs such as Gendicine for cancer and Neovasculgen for peripheral artery disease. Since then, the pharma sector is focusing on developing gene-based drugs for various diseases. After the discovery of the RNA interference (RNAi) mechanism, the development of siRNA-based gene therapy has been accelerated immensely. siRNA-based treatment for hereditary transthyretin-mediated amyloidosis (hATTR) using Onpattro and acute hepatic porphyria (AHP) by Givlaari and three more FDA-approved siRNA drugs has set up a milestone and further improved the confidence for the development of gene therapeutics for a spectrum of diseases. siRNA-based gene drugs have more advantages over other gene therapies and are under study to treat different types of diseases such as viral infections, cardiovascular diseases, cancer, and many more. However, there are a few bottlenecks to realizing the full potential of siRNA-based gene therapy. They include chemical instability, nontargeted biodistribution, undesirable innate immune responses, and off-target effects. This review provides a comprehensive view of siRNA-based gene drugs: challenges associated with siRNA delivery, their potential, and future prospects.

A novel Anti-ROS osteoblast-specific delivery system for ankylosing spondylitis treatment via suppression of both inflammation and pathological new bone formation

Ankylosing spondylitis (AS) is a common rheumatic disorder distinguished by chronic inflammation and heterotopic ossification at local entheses sites. Currently available medications, including nonsteroidal anti-inflammatory drugs (NSAIDs), disease-modifying anti-rheumatic drugs (DMARDs) and TNF inhibitors, are limited by side effects, high costs and unclear inhibitory effects on heterotopic ossification. Herein, we developed manganese ferrite nanoparticles modified by the aptamer CH6 (CH6-MF NPs) that can efficiently scavenge ROS and actively deliver siRNA into hMSCs and osteoblasts in vivo for effective AS treatment. CH6-MF NPs loaded with BMP2 siRNA (CH6-MF-Si NPs) effectively suppressed abnormal osteogenic differentiation under inflammatory conditions in vitro. During their circulation and passive accumulation in inflamed joints in the Zap70^mut mouse model, CH6-MF-Si NPs attenuated local inflammation and rescued heterotopic ossification in the entheses. Thus, CH6-MF NPs may be an effective inflammation reliever and osteoblast-specific delivery system, and CH6-MF-Si NPs have potential for the dual treatment of chronic inflammation and heterotopic ossification in AS.

Induction of apoptosis and autosis in cardiomyocytes by the combination of homocysteine and copper via NOX-mediated p62 expression

High levels of homocysteine (Hcy) associated with cardiovascular events are accompanied by increased copper (Cu) concentrations in the blood. Hcy has been shown to promote endothelial dysfunction, whereas the effect of Hcy on cardiomyocytes and the role of Cu in the pathogenesis remain less understood. In the present study, it is demonstrated that the combination of Hcy and Cu²⁺-induced apoptosis and autosis of cardiomyocytes simultaneously, and thus led to cardiac dysfunction in hyperhomocysteinemic rats. These effects were associated with p22^phox activation and NADPH oxidase (NOX)-mediated p62 upregulation. Inhibition of the expression of p22^phox or p62 in cardiomyocytes significantly attenuated Hcy and Cu²⁺-mediated reactive oxygen species (ROS) generation and cell death. Furthermore, interrupting the NOX-p62 axis prevented diastolic dysfunction in hyperhomocysteinemic rats (HcyR). These findings establish that the induction of apoptosis and autosis of cardiomyocytes through stimulating the NOX-p62-signaling pathway constitutes a novel mechanism of Hcy and Cu-induced cardiac dysfunction.

Improving the anti-inflammatory efficacy of dexamethasone in the treatment of rheumatoid arthritis with polymerized stealth liposomes as a delivery vehicle

Rheumatoid arthritis (RA) is an autoimmune disease that causes chronic inflammation of the joints of the body. Although liposomes are a promising drug delivery vehicle, there is still a challenge of using conventional liposomes for the treatment of RA due to their short circulation time and physicochemical instability in blood vessels. Here, we report the formation of polymerized stealth liposomes composed of 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine (DC8,9PC) and 1,2-distearoyl-sn-glycero-3-phospho-ethanolamine-poly(ethyleneglycol) (DSPE-PEG2000) with a thin-film hydration method, in which DC8,9PC molecules are cross-linked in the bilayer of the liposomes by UV irradiation and the PEG chains present at the surface of the liposomes provide a stealth layer. We demonstrate that the polymerized stealth liposomes are stable and show long circulation time in blood vessels. They can be internalized by cells without significant toxicity. After being injected into arthritic rats, the polymerized stealth liposomes with loaded dexamethasone (Dex) show long blood circulation time and accumulate preferentially in inflamed joints, consequently suppressing the level of proinflammatory cytokines (TNF-α and IL-1β) in joint tissues, reducing the swelling of inflamed joints and alleviating the progression of RA. We believe that polymerized stealth liposomes can be used as a promising drug delivery vehicle for various therapeutic applications.

Polycation fluorination improves intraperitoneal siRNA delivery in metastatic pancreatic cancer

Pancreatic ductal adenocarcinoma (PDAC) is a growing medical problem associated with extensive metastasis and high mortality. Intraperitoneal (IP) administration of therapeutics promises to help the treatment of cancers originated from organs in the peritoneal cavity. In this study, we evaluated how physicochemical properties of self-assembled polycation/siRNA nanoparticles affect their IP delivery efficacy in an orthotopic PDAC model. We have examined the effect of covalent polycation modification with lipophobic and hydrophobic tetrafluoro-p-toluic acid (TFTA), hydrophobic cholesterol, and hydrophilic poly(ethylene glycol) respectively. The surface charge of the three different nanoparticles was also modulated by coating the surface with serum albumin. We found that positively charged fluorine-containing particles with lipophobic properties based on a mixture of positively charged polymeric AMD3100 CXCR4 antagonist (PAMD) and PAMD modified with TFTA (mPAMD-TFTA)/siRNA displayed the best cell uptake and transfection efficacy in vitro. Biodistribution evaluation of the nanoparticles in a syngeneic orthotopic PDAC model revealed that the fluorine-containing formulation also achieved the highest PDAC tumor accumulation after IP administration. With a combination of CXCR4 inhibition by PAMD and PLK1 downregulation by siRNA, the treatment with mPAMD-TFTA/siPLK1 showed significant inhibition of both primary and metastatic PDAC tumors. Overall, our study provides insights into and guides the design of the nanoparticles for improved IP delivery of siRNA in PDAC.

Recent developments in natural and synthetic polymeric drug delivery systems used for the treatment of osteoarthritis

Osteoarthritis (OA), is a common musculoskeletal disorder that will progressively increase in older populations and is expected to be the most dominant cause of disability in the world population by 2030. The progression of OA is controlled by a multi-factorial pathway that has not been completely elucidated and understood yet. However, over the years, research efforts have provided a significant understanding of some of the processes contributing to the progression of OA. Both cartilage and bone degradation processes induce articular cells to produce inflammatory mediators that produce proinflammatory cytokines that block the synthesis of collagen type II and aggrecan, the major components of cartilage. Systemic administration and intraarticular injection of anti-inflammatory agents are the first-line treatments of OA. However, small anti-inflammatory molecules are rapidly cleared from the joint cavity which limits their therapeutic efficacy. To palliate this strong technological drawback, different types of polymeric materials such as microparticles, nanoparticles, and hydrogels, have been examined as drug carriers for the delivery of therapeutic agents to articular joints. The main purpose of this review is to provide a summary of recent developments in natural and synthetic polymeric drug delivery systems for the delivery of anti-inflammatory agents to arthritic joints. Furthermore, this review provides an overview of the design rules that have been proposed so far for the development of drug carriers used in OA therapy. Overall it is difficult to state clearly which polymeric platform is the most efficient one because many advantages and disadvantages could be pointed to both natural and synthetic formulations. That requires further research in the near future.

Extracellular Vesicles - Advanced Nanocarriers in Cancer Therapy: Progress and Achievements

Extracellular vesicles (EVs) are a class of cell-derived, lipid bilayer membrane composed vesicles, and some of them such as exosomes and ectosomes have been proven, playing remarkable roles in transmitting intercellular information, and being involved in each property of cell physiological activities. Nowadays, EVs are considered as potential nanocarriers which could partially resolve the problems of current chemotherapy because of their distinctive advantages. As endogenous membrane encompassed vesicles with nanosize, EVs are able to pass through the natural barriers with prolonged circulation time in vivo and have intrinsic cell targeting properties, they are less toxic, and less immunogenic. Recently, studies focusing on EV-based drug delivery system for cancer therapy have exploded dramatically. This review aims to outline the current applications of EVs as potential nanosized drug carriers in cancer therapy. Firstly, the characteristics and biofunctions of each EV subtype are described. Then the variety of therapeutic cargoes, the loading methods, and the targeting strategy of engineered EVs are emphatically introduced. Thereafter the pros and cons of EVs applied as therapeutic carriers, as well as the future prospects in this field, are discussed.

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

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

Applications of RNA interference in the treatment of arthritis

RNA interference (RNAi) is a cellular mechanism for post-transcriptional gene regulation mediated by small interfering RNA (siRNA) and microRNA. siRNA-based therapy holds significant promise for the treatment of a wide-range of arthritic diseases. siRNA selectively suppresses the expression of a gene product and can thus achieve the specificity that is lacking in small molecule inhibitors. The potential use of siRNA-based therapy in arthritis, however, has not progressed to clinical trials despite ample evidence for efficacy in preclinical studies. One of the main challenges to clinical translation is the lack of a suitable delivery vehicle to efficiently and safely access diverse pathologies. Moreover, the ideal targets in treatment of arthritides remain elusive given the complexity and heterogeneity of these disease pathogeneses. Herein, we review recent preclinical studies that use RNAi-based drug delivery systems to mitigate inflammation in models of rheumatoid arthritis and osteoarthritis. We discuss a self-assembling peptide-based nanostructure that demonstrates the potential of overcoming many of the critical barriers preventing the translation of this technology to the clinic.

Dynamic profiles, biodistribution and integration evaluation after intramuscular/intravenous delivery of a novel therapeutic DNA vaccine encoding chicken type II collagen for rheumatoid arthritis in vaccinated normal rodent

Background

The persistence, biodistribution, and risk of integration into the host genome of any new therapeutic DNA vaccine must be established in preclinical studies. We previously developed the DNA vaccine pcDNA-CCOL2A1 encoding chicken type II collagen (CCII) for the treatment of rheumatoid arthritis (RA). In the present study, we characterized its dynamic profile, biodistribution, and potential for genomic DNA integration in normal vaccinated rodent.

Results

A real-time quantitative PCR analysis (RT-qPCR) of animals administered a single dose of pcDNA-CCOL2A1 (300 μg/kg by intramuscular injection) showed that CCOL2A1 mRNA level in the blood peaked between 2 and 6 h post-immunization and then rapidly declined, and was undetectable between day 1–42. CCOL2A1 transcript was detected at the muscle injection site on days 3–14 post-immunization. Starting from day 14, the transcript was detected in the heart, liver, lung, and kidney but not in the spleen or thymus, and was expressed only in the lung on day 28. There was no CCOL2A1 mRNA present in the testes or ovaries at any time point. Non-invasive in vivo fluorescence imaging revealed CCII protein expression from 2 h up to day 10 and from 2 h up to day 35 after administration of pcDNA-CCOL2A1 via the intravenous and intramuscular routes, respectively; the protein had disappeared by day 42. Importantly, CCOL2A1 was not integrated into the host genome.

Conclusions

These results indicate that pcDNA-CCOL2A1 vaccine is rapidly cleared within a short period of time and is therefore safe, and merits further development as a therapeutic vaccine for RA treatment.

Lipidoid-siRNA Nanoparticle-Mediated IL-1β Gene Silencing for Systemic Arthritis Therapy in a Mouse Model

Interleukin-1 beta (IL-1β) plays a central role in the induction of rheumatoid arthritis (RA). In the present study, we demonstrated that lipidoid-polymer hybrid nanoparticle (FS14-NP) can efficiently deliver siRNA against IL-1β (siIL-1β) to macrophages and effectively suppress the pathogenesis of experimental arthritis induced by collagen antibody (CAIA mice). FS14-NP/siIL-1β achieved approximately 70% and 90% gene-silencing efficiency in the RAW 264.7 cell line and intraperitoneal macrophages, respectively. Intravenous administration of FS14-NP/siRNA led to rapid accumulation of siRNA in macrophages within the arthritic joints. Furthermore, FS14-NP/siIL-1β treatment lowered the expression of pro-inflammatory cytokines in arthritic joints and dramatically attenuated ankle swelling, bone erosion, and cartilage destruction. These results demonstrate that FS14-NP/siIL-1β may represent an effective therapy for systemic arthritis and other inflammatory disorders.

Osteoblastic PLEKHO1 contributes to joint inflammation in rheumatoid arthritis

Background

Osteoblasts participating in the inflammation regulation gradually obtain concerns. However, its role in joint inflammation of rheumatoid arthritis (RA) is largely unknown. Here, we investigated the role of osteoblastic pleckstrin homology domain-containing family O member 1 (PLEKHO1), a negative regulator of osteogenic lineage activity, in regulating joint inflammation in RA.

Methods

The level of osteoblastic PLEKHO1 in RA patients and collagen-induced arthritis (CIA) mice was examined. The role of osteoblastic PLEKHO1 in joint inflammation was evaluated by a CIA model and a K/BxN serum-transfer arthritis (STA) model which were induced in osteoblast-specific Plekho1 conditional knockout mice and mice expressing high Plekho1 exclusively in osteoblasts, respectively. The effect of osteoblastic PLEKHO1 inhibition was explored in a CIA mice model and a non-human primate arthritis model. The mechanism of osteoblastic PLEKHO1 in regulating joint inflammation were performed by a series of in vitro studies.

Results

PLEKHO1 was highly expressed in osteoblasts from RA patients and CIA mice. Osteoblastic Plekho1 deletion ameliorated joint inflammation, whereas overexpressing Plekho1 only within osteoblasts exacerbated local inflammation in CIA mice and STA mice. PLEKHO1 was required for TRAF2-mediated RIP1 ubiquitination to activate NF-κB for inducing inflammatory cytokines production in osteoblasts. Moreover, osteoblastic PLEKHO1 inhibition diminished joint inflammation and promoted bone formation in CIA mice and non-human primate arthritis model.

Conclusions

These data strongly suggest that the highly expressed PLEKHO1 in osteoblasts contributes to joint inflammation in RA. Targeting osteoblastic PLEKHO1 may exert dual therapeutic action of alleviating joint inflammation and promoting bone formation in RA.

Superparamagnetic iron oxide nanoparticles modified with polyethylenimine and galactose for siRNA targeted delivery in hepatocellular carcinoma therapy

Introduction

A safe and effective in vivo siRNA delivery system is a prerequisite for liver tumor treatment based on siRNA cancer therapeutics. Nanoparticles based on superparamagnetic iron oxide (SPIO) provide a promising delivery system. In this study, we aimed to explore a novel nanoparticle, which is composed of SPIO.

Materials and methods

The particles have a core of iron oxide that is modified by galactose (Gal) and polyethylenimine (PEI), which act as shells, providing targeted delivery of therapeutic siRNA to the liver cancer. Gal-PEI-SPIO nanoparticles were synthesized, and the characteristics of the Gal-PEI-SPIO encapsulated with siRNA were analyzed.

Results

The particles remained nanoparticles and displayed negligible cytotoxicity when loaded with siRNA. In a serum stability assay, the Gal-PEI-SPIO nanoparticles could shield the siRNA from serum degradation and prolong the half-life of the siRNA in the system. Simultaneously, we found that the mixture could be efficiently taken up by Hepa1–6 cells in a flow cytometry assay. To study the anticancer effect, quantitative polymerase chain reaction and Western blotting were used to validate the silencing efficacy of the complexes in vitro. Subsequently, the nanoparticle mixtures were administered intravenously to tumor-bearing mice to explore the tissue distribution and the effect of the siRNA against cancer. We found that the nanoparticles could provide targeted siRNA delivery, accumulate easily in orthotopic tumors, enhance siRNA accumulation in the tumor tissues for 24 h and protect the siRNA from serum nuclease degradation in comparison with the control group. After these study procedures, the mice were sacrificed, and the tumors were removed to compare the tumor size and analyze the therapeutic effect on tumor growth. The tumor volume and the liver/body weight ratio were significantly reduced in the si-c-Met therapy groups. Additionally, the mRNA levels were also lower than those observed in the controls.

Conclusion

Based on these results, we concluded that Gal-PEI-SPIO represents a promising and efficient platform for siRNA delivery in tumor therapy.

Cartilage-targeting drug delivery: can electrostatic interactions help?

Current intra-articular drug delivery methods do not guarantee sufficient drug penetration into cartilage tissue to reach cell and matrix targets at the concentrations necessary to elicit the desired biological response. Here, we provide our perspective on the utilization of charge-charge (electrostatic) interactions to enhance drug penetration and transport into cartilage, and to enable sustained binding of drugs within the tissue's highly negatively charged extracellular matrix. By coupling drugs to positively charged nanocarriers that have optimal size and charge, cartilage can be converted from a drug barrier into a drug reservoir for sustained intra-tissue delivery. Alternatively, a wide variety of drugs themselves can be made cartilage-penetrating by functionalizing them with specialized positively charged protein domains. Finally, we emphasize that appropriate animal models, with cartilage thickness similar to that of humans, must be used for the study of drug transport and retention in cartilage.

Mannan-Binding Lectin-Associated Serine Protease 1/3 Cleavage of Pro-Factor D into Factor D In Vivo and Attenuation of Collagen Antibody-Induced Arthritis through Their Targeted Inhibition by RNA Interference-Mediated Gene Silencing

The complement system is proposed to play an important role in the pathogenesis of rheumatoid arthritis (RA). The complement system mannan-binding lectin-associated serine proteases (MASP)-1/3 cleave pro-factor D (proDf; inactive) into Df (active), but it is unknown where this cleavage occurs and whether inhibition of MASP-1/3 is a relevant therapeutic strategy for RA. In the present study, we show that the cleavage of proDf into Df by MASP-1/3 can occur in the circulation and that inhibition of MASP-1/3 by gene silencing is sufficient to ameliorate collagen Ab-induced arthritis in mice. Specifically, to examine the cleavage of proDf into Df, MASP-1/3-producing Df-/- liver tissue (donor) was transplanted under the kidney capsule of MASP-1/3-/- (recipient) mice. Five weeks after the liver transplantation, cleaved Df was present in the circulation of MASP-1/3-/- mice. To determine the individual effects of MASP-1/3 and Df gene silencing on collagen Ab-induced arthritis, mice were injected with scrambled, MASP-1/3-targeted, or Df-targeted small interfering RNAs (siRNAs). The mRNA levels for MASP-1 and -3 decreased in the liver to 62 and 58%, respectively, in mice injected with MASP-1/3 siRNAs, and Df mRNA decreased to 53% in the adipose tissue of mice injected with Df siRNAs; additionally, circulating MASP-1/3 and Df protein levels were decreased. In mice injected with both siRNAs the clinical disease activity, histopathologic injury scores, C3 deposition, and synovial macrophage/neutrophil infiltration were significantly decreased. Thus, MASP-1/3 represent a new therapeutic target for the treatment of RA, likely through both direct effects on the lectin pathway and indirectly through the alternative pathway.

Deregulation and therapeutic potential of microRNAs in arthritic diseases

Epigenetic abnormalities are part of the pathogenetic alterations involved in the development of rheumatic disorders. In this context, the main musculoskeletal cell lineages, which are generated from the pool of mesenchymal stromal cells (MSCs), and the immune cells that participate in rheumatic diseases are deregulated. In this Review, we focus on microRNA (miRNA)-mediated regulatory pathways that control cell proliferation, drive the production of proinflammatory mediators and modulate bone remodelling. The main studies that identify miRNAs as regulators of immune cell fate, MSC differentiation and immunomodulatory properties - parameters that are altered in rheumatoid arthritis (RA) and osteoarthritis (OA) - are also discussed, with emphasis on the importance of miRNAs in the regulation of cellular machinery, extracellular matrix remodelling and cytokine release. A deeper understanding of the involvement of miRNAs in rheumatic diseases is needed before these regulatory pathways can be explored as therapeutic approaches for patients with RA or OA.

The Interplay Between Monocytes/Macrophages and CD4(+) T Cell Subsets in Rheumatoid Arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease characterized by inflammation of the synovial lining (synovitis). The inflammation in the RA joint is associated with and driven by immune cell infiltration, synovial hyperproliferation, and excessive production of proinflammatory mediators, such as tumor necrosis factor α (TNFα), interferon γ (IFNγ), interleukin (IL)-1β, IL-6, and IL-17, eventually resulting in damage to the cartilage and underlying bone. The RA joint harbors a wide range of immune cell types, including monocytes, macrophages, and CD4(+) T cells (both proinflammatory and regulatory). The interplay between CD14(+) myeloid cells and CD4(+) T cells can significantly influence CD4(+) T cell function, and conversely, effector vs. regulatory CD4(+) T cell subsets can exert profound effects on monocyte/macrophage function. In this review, we will discuss how the interplay between CD4(+) T cells and monocytes/macrophages may contribute to the immunopathology of RA.

A New Approach for the Treatment of Arthritis in Mice with a Novel Conjugate of an Anti-C5aR1 Antibody and C5 Small Interfering RNA

Rheumatoid arthritis (RA) is an inflammatory autoimmune joint disease in which the complement system plays an important role. Of the several components of complement, current evidence points to C5 as the most important inducer of inflammation. Several groups generated Abs or small interfering RNAs (siRNAs) or small molecule inhibitors against C5 and C5aR1 (CD88) that have showed some efficacy in RA in animal models. However, none of these candidate therapeutics has moved from bench to bedside. In this study, we test in collagen Ab-induced arthritis (CAIA) a new therapeutic strategy using a novel anti-C5ab-C5 siRNA conjugate. We first demonstrate that although C5aR2 or C5L2 (GPR77) plays no role in CAIA, C5aR1 contributes to pathogenesis. We demonstrate that injection of siRNAs blocking C5, C5aR1, or the combination decreased clinical disease activity in mice with CAIA by 45%, 51%, and 58%, respectively. Anti-C5 Ab (BB5.1) has only limited efficacy, but significantly reduced arthritis up to 66%. We then generated a novel anti-C5aR1 Ab-protamine-C5 siRNA conjugate. To our knowledge, we show for the first time that whereas unconjugated Ab plus siRNAs reduce arthritis by 19%, our anti-C5aR1 Ab-protamine-C5 siRNA conjugate was effective in reducing arthritis by 83% along with a parallel decrease in histopathology, C3 deposition, neutrophils, and macrophages in the joints of mice with CAIA. These data suggest that by targeting anti-C5 siRNAs to the receptor for its C5a activation fragment (C5aR1), a striking clinical effect can be realized.

Targeting dendritic cell function during systemic autoimmunity to restore tolerance

Systemic autoimmune diseases can damage nearly every tissue or cell type of the body. Although a great deal of progress has been made in understanding the pathogenesis of autoimmune diseases, current therapies have not been improved, remain unspecific and are associated with significant side effects. Because dendritic cells (DCs) play a major role in promoting immune tolerance against self-antigens (self-Ags), current efforts are focusing at generating new therapies based on the transfer of tolerogenic DCs (tolDCs) during autoimmunity. However, the feasibility of this approach during systemic autoimmunity has yet to be evaluated. TolDCs may ameliorate autoimmunity mainly by restoring T cell tolerance and, thus, indirectly modulating autoantibody development. In vitro induction of tolDCs loaded with immunodominant self-Ags and subsequent cell transfer to patients would be a specific new therapy that will avoid systemic immunosuppression. Herein, we review recent approaches evaluating the potential of tolDCs for the treatment of systemic autoimmune disorders.

New and emerging treatments for osteoarthritis management: will the dream come true with personalized medicine?

INTRODUCTION

Osteoarthritis (OA) is a dynamic process involving the main tissues of the joint for which a global approach should be considered. No disease-modifying OA drug (DMOAD) has yet been approved. New therapeutic strategies are needed that would be cost effective by reducing the need for pharmacological interventions and surgical management while targeting specific pathways leading to OA. The treatment landscape of OA is about to change based on new agents having shown some structural effects and emerging therapies with DMOAD effects.

AREAS COVERED

In this review based on a Medline (via PubMed) search, promising new and emerging therapies with a potential structural effect (DMOAD) will be discussed including growth factors, platelet-rich plasma, autologous stem cells, bone remodeling modulators, cytokine inhibition, gene therapy, and RNA interference.

EXPERT OPINION

DMOAD development should focus on targeting some phenotypes of OA patients evidenced with sensitive techniques such as magnetic resonance imaging, as a single treatment will unlikely be appropriate for all OA patients. This will allow the development of DMOADs based on personalized medicine. An exciting new era in DMOAD development is within reach, provided future clinical trials are sufficiently powered, systematically designed, use the appropriate evaluation tools, and target the appropriate categories of OA patients.

Polyethyleneimine-functionalized iron oxide nanoparticles for systemic siRNA delivery in experimental arthritis

AIMS

This study aimed to examine the efficacy of a nanocarrier (polyethyleneimine [PEI]-superparamagnetic iron oxide nanoparticle [SPIO]), composed of a core of iron oxide and a shell of PEI, in the systemic delivery of therapeutic siRNA to experimental arthritic joints.

MATERIALS & METHODS

PEI-SPIO/siRNA nanoparticles were synthesized and characterized in vitro. Nanoparticles were administered intravenously to arthritic rats to analyze cellular uptake, tissue distribution and the therapeutic effect of a siRNA against the IL-2/-15 receptor β chain (IL-2/IL-15Rβ).

RESULTS

PEI-SPIOs loaded with siRNA displayed negligible cytotoxicity, improved siRNA stability, efficient uptake by macrophages and the ability to induce specific gene silencing in vitro. PEI-SPIO-delivered siRNA accumulated easily in inflamed joints and was efficiently taken up by joint macrophages and T cells. Although IL-2/IL-15Rβ siRNA-loaded PEI-SPIOs alone were efficacious in the treatment of experimental arthritis, combination therapy with both PEI-SPIO/IL-2/IL-15Rβ siRNA and a magnetic field displayed an additive anti-inflammatory effect.

CONCLUSION

PEI-functionalized SPIOs can be employed for systemic siRNA delivery in rheumatoid arthritis and enhanced therapeutic benefit can be achieved by the use of an external magnetic field.

The role of miR-155 in regulatory T cells and rheumatoid arthritis

Recently, various micro(mi)RNAs have been found deregulated in the setting of rheumatoid arthritis (RA), but their role in the pathogenesis of this disease remains a matter of debate. In the meanwhile, increasing evidence indicates a defective function of regulatory T cells (Tregs) in RA. This review discusses relevant studies addressing the function of Tregs and Cytotoxic T-Lymphocyte Antigen 4 in RA, provides recent data on the role of miRNAs for Tregs homeostasis, and focuses on the role of miR-155 in Tregs. In a final perspective section we discuss the potential impact of therapeutic miR-155 modulation in RA.

The miR-17 ∼ 92 Cluster: A Key Player in the Control of Inflammation during Rheumatoid Arthritis

MicroRNAs (miRNAs) are now recognized as essential regulators of gene expression in plants and animals. They potentially modulate the expression of multiple genes thereby enabling homeostatic settings in physiological conditions. Their role is also increasingly considered in many diseases in which deregulated epigenetic mechanisms induce aberrant gene expression. Work conducted in our laboratory has recently led to the identification of miRNAs essential for the control of inflammatory reactions that occur during rheumatoid arthritis (RA). In this review, we describe two such miRNAs, members of the miR-17 ∼ 92 cluster, which has been previously implicated in cancer. Based on our data and on predicted miRNA:mRNA interactions, we will extrapolate a model whereby the miR-17 ∼ 92 cluster appears as a global regulator of the Apoptosis Signal-Regulating Kinase 1 signalosome, a central actor in the inflammatory pathways activated during RA. We will also discuss the potential therapeutic outcomes emerging from this model.

Computational analysis of siRNA recognition by the Ago2 PAZ domain and identification of the determinants of RNA-induced gene silencing

RNA interference (RNAi) is a highly specialized process of protein-siRNA interaction that results in the regulation of gene expression and cleavage of target mRNA. The PAZ domain of the Argonaute proteins binds to the 3' end of siRNA, and during RNAi the attaching end of the siRNA switches between binding and release from its binding pocket. This biphasic interaction of the 3' end of siRNA with the PAZ domain is essential for RNAi activity; however, it remains unclear whether stronger or weaker binding with PAZ domain will facilitate or hinder the overall RNAi process. Here we report the correlation between the binding of modified siRNA 3' overhang analogues and their in vivo RNAi efficacy. We found that higher RNAi efficacy was associated with the parameters of lower Ki value, lower total intermolecular energy, lower free energy, higher hydrogen bonding, smaller total surface of interaction and fewer van der Waals interactions. Electrostatic interaction was a minor contributor to compounds recognition, underscoring the presence of phosphate groups in the modified analogues. Thus, compounds with lower binding affinity are associated with better gene silencing. Lower binding strength along with the smaller interaction surface, higher hydrogen bonding and fewer van der Waals interactions were among the markers for favorable RNAi activity. Within the measured parameters, the interaction surface, van der Waals interactions and inhibition constant showed a statistically significant correlation with measured RNAi efficacy. The considerations provided in this report will be helpful in the design of new compounds with better gene silencing ability.