Trojan horses and guided missiles: targeted therapies in the war on arthritis

The therapeutic potential of immunoengineering for systemic autoimmunity

Disease-modifying drugs have transformed the treatment options for many systemic autoimmune diseases. However, an evolving understanding of disease mechanisms, which might vary between individuals, is paving the way for the development of novel agents that operate in a patient-tailored manner through immunophenotypic regulation of disease-relevant cells and the microenvironment of affected tissue domains. Immunoengineering is a field that is focused on the application of engineering principles to the modulation of the immune system, and it could enable future personalized and immunoregulatory therapies for rheumatic diseases. An important aspect of immunoengineering is the harnessing of material chemistries to design technologies that span immunologically relevant length scales, to enhance or suppress immune responses by re-balancing effector and regulatory mechanisms in innate or adaptive immunity and rescue abnormalities underlying pathogenic inflammation. These materials are endowed with physicochemical properties that enable features such as localization in immune cells and organs, sustained delivery of immunoregulatory agents, and mimicry of key functions of lymphoid tissue. Immunoengineering applications already exist for disease management, and there is potential for this new discipline to improve disease modification in rheumatology.

Prodrug-based nanomedicines for rheumatoid arthritis

Most antirheumatic drugs with high toxicity exhibit a narrow therapeutic window due to their nonspecific distribution in the body, leading to undesirable side effects and reduced patient compliance. To in response to these challenges, prodrug-based nanoparticulate drug delivery systems (PNDDS), which combines prodrug strategy and nanotechnology into a single system, resulting their many advantages, including stability for prodrug structure, the higher drug loading capacity of the system, improving the target activity and bioavailability, and reducing their untoward effects. PNDDS have gained attention as a method for relieving arthralgia syndrome of rheumatoid arthritis in recent years. This article systematically reviews prodrug-based nanocarriers for rheumatism treatment, including Nano systems based on prodrug-encapsulated nanomedicines and conjugate-based nanomedicines. It provides a new direction for the clinical treatment of rheumatoid arthritis.

New insights in osteoarthritis diagnosis and treatment: Nano-strategies for an improved disease management

Osteoarthritis (OA) is a common chronic joint pathology that has become a predominant cause of disability worldwide. Even though the origin and evolution of OA rely on different factors that are not yet elucidated nor understood, the development of novel strategies to treat OA has emerged in the last years. Cartilage degradation is the main hallmark of the pathology though alterations in bone and synovial inflammation, among other comorbidities, are also involved during OA progression. From a molecular point of view, a vast amount of signaling pathways are implicated in the progression of the disease, opening up a wide plethora of targets to attenuate or even halt OA. The main purpose of this review is to shed light on the recent strategies published based on nanotechnology for the early diagnosis of the disease as well as the most promising nano-enabling therapeutic approaches validated in preclinical models. To address the clinical issue, the key pathways involved in OA initiation and progression are described as the main potential targets for OA prevention and early treatment. Furthermore, an overview of current therapeutic strategies is depicted. Finally, to solve the drawbacks of current treatments, nanobiomedicine has shown demonstrated benefits when using drug delivery systems compared with the administration of the equivalent doses of the free drugs and the potential of disease-modifying OA drugs when using nanosystems. We anticipate that the development of smart and specific bioresponsive and biocompatible nanosystems will provide a solid and promising basis for effective OA early diagnosis and treatment. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Implantable Materials and Surgical Technologies > Nanotechnology in Tissue Repair and Replacement.

[Research progress of nanomaterials for intra-articular targeted drug delivery in treatment of osteoarthritis]

Objective

To review the research progress of intra-articular targeted delivery of nanomaterials in the treatment of osteoarthritis (OA).

Methods

The domestic and foreign related literature on intra-articular targeted delivery of nanomaterials for the treatment of OA was extensively reviewed, and their targeting strategies were discussed and summarized.

Results

Rapid drug clearance from the joint remains a critical limitation in drug efficacy. Nanocarriers can not only significantly improve the residence profiles of drugs in the joint, but also achieve targeted delivery of drugs to specific joint tissues through active or passive targeting strategies.

Conclusion

With the continuous development of various emerging tissue- or cell-specific drugs, the targeted delivery of drugs with nanomaterials promise to realize the clinical translation of these drugs in the treatment of OA.

Inflammation-homing "living drug depot" for efficient arthritis treatment

Delivering therapeutic agents efficiently to inflamed joints remains an intractable problem in rheumatoid arthritis (RA) treatment due to the complicated physiological barriers. Circulating monocytes could selectively migrate to inflamed sites and differentiate into resident macrophages to aggravate RA. Therefore, a drug carrier that can be specifically internalized by circulating monocytes and switch monocytes into anti-inflammatory phenotype when reaching inflamed sites, might bypass the in vivo physiological barriers and achieve efficient RA therapy. Herein, we design a dextran sulfate (DS) functionalized nanoparticle (ZDNP) to selectively deliver anti-inflammatory agent dexamethasone (Dex) to circulating monocytes via the scavenger receptors on monocytes. Monocytes engulfing drug-loaded ZDNP could subsequently home to arthritic joints and act as a "living drug depot" to combat RA. Results revealed that ZDNP could be preferentially internalized by circulating monocytes when intravenously administrated in vivo. In a rat arthritic model, we found that circulating monocytes remarkably facilitated drug distribution and retention in inflamed joints. Moreover, monocytes engulfing drug-loaded nanoparticles exhibited favorable anti-inflammatory ability and M2-biased differentiation. Our work offers a facile approach to achieve site-directed anti-inflammatory therapy by taking advantage of the inflammation-homing ability of circulating monocytes. STATEMENT OF SIGNIFICANCE: Circulating monocytes can migrate to inflamed sites and then differentiate into macrophages to aggravate arthritis. Therefore, a drug carrier that can be specifically internalized by circulating monocytes and switch monocytes into anti-inflammatory phenotype when reaching inflamed sites may achieve efficient arthritis therapy. Here, we designed a monocyte-targeting nanoparticle (ZDNP) to selectively deliver anti-inflammatory Dex to circulating monocytes. When injected intravenously, ZDNP was effectively internalized by circulating monocytes via a scavenger receptor and subsequently was transported to arthritic joints, where monocytes engulfing the drug-loaded nanoparticles could switch to an anti-inflammatory phenotype to inhibit arthritis progress. We provide detailed evidence about the in vivo fate of ZDNP and unravel how monocytes act as a "living drug depot" to achieve site-directed arthritis therapy.

Delivery of germacrone (GER) using macrophages-targeted polymeric nanoparticles and its application in rheumatoid arthritis

Macrophages can transform into M1 (pro-inflammatory) and M2 (anti-inflammatory) phenotypes, which mediate the immune/inflammatory response in rheumatoid arthritis (RA). Activated M1 phenotype macrophages and overexpression of folate (FA) receptors are abundant in inflammatory synovium and joints and promote the progression of RA. Germacrone (GER) can regulate the T helper 1 cell (Th1)/the T helper 2 cell (Th2) balance to delay the progression of arthritis. To deliver GER to inflammatory tissue cells to reverse M1-type proinflammatory cells and reduce inflammation, FA receptor-targeting nanocarriers loaded with GER were developed. In activated macrophages, FA-NPs/DiD showed significantly higher uptake efficiency than NPs/DiD. In vitro experiments confirmed that FA-NPs/GER could promote the transformation of M1 macrophages into M2 macrophages. In adjuvant-induced arthritis (AIA) rats, the biodistribution profiles showed selective accumulation at the inflammatory site of FA-NPs/GER, and significantly reduced the swelling and inflammation infiltration of the rat's foot. The levels of pro-inflammatory cytokines (TNF-α, IL-1β) in the rat's inflammatory tissue were significantly lower than other treatment groups, which indicated a significant therapeutic effect in AIA rats. Taken together, macrophage-targeting nanocarriers loaded with GER are a safe and effective method for the treatment of RA.

Therapeutic nanocarriers comprising extracellular matrix-inspired peptides and polysaccharides

INTRODUCTION

The extracellular matrix (ECM) is vital for cell and tissue development. Given its importance, extensive work has been conducted to develop biomaterials and drug delivery vehicles that capture features of ECM structure and function.

AREAS COVERED

This review highlights recent developments of ECM-inspired nanocarriers and their exploration for drug and gene delivery applications. Nanocarriers that are inspired by or created from primary components of the ECM (e.g. elastin, collagen, hyaluronic acid (HA), or combinations of these) are explicitly covered. An update on current clinical trials employing elastin-like proteins is also included.

EXPERT OPINION

Novel ECM-inspired nanoscale structures and conjugates continue to be of great interest in the materials science and bioengineering communities. Hyaluronic acid nanocarrier systems in particular are widely employed due to the functional activity of HA in mediating a large number of disease states. In contrast, collagen-like peptide nanocarriers are an emerging drug delivery platform with potential relevance to a myriad of ECM-related diseases, making their continued study most pertinent. Elastin-like peptide nanocarriers have a well-established tolerability and efficacy track record in preclinical analyses that has motivated their recent advancement into the clinical arena.

Research progress in the application of bile acid-drug conjugates: A "trojan horse" strategy

Bile acid transporters are highly expressed in intestinal cells and hepatocytes, and they determine the uptake of drugs in cells by modulating cellular entry and exit. In order to improve the oral bioavailability of drugs and investigate the potential application prospects of drugs used to target cancer, numerous studies have adopted these transporters to identify prodrug strategies. Through the connection of covalent bonds between drugs and bile acids, the resulting bile acid-drug conjugates continue to be recognized as similar to natural unmodified bile acid and is translocated by the transporter. The present mini-review provides a brief summary of recent progress of the application of bile acid-drug conjugates based primarily on ASBT, NTCP, and OATP, with the hope of contributing to subsequent research.

SPECT imaging and highly efficient therapy of rheumatoid arthritis based on hyperbranched semiconducting polymer nanoparticles

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease. Although significant progress has been made in clinical treatment, joint inflammation may continue or worsen, and may even progress to the end-stage that requires joint replacement. Traditional therapy using methotrexate (MTX) would cause serious off-target systemic toxicities. Therefore, it is crucial to effectively and specifically deliver MTX to targeted inflamed joints to decrease its adverse systemic toxicities and improve its therapeutic index. Herein, we develop multifunctional nanocarriers for diagnostic radioisotope (99mTc) labeling and therapeutic targeted drug (MTX) delivery by using PEGylated hyperbranched semiconducting polymer nanoparticles (HSP-PEG-NPs) as carriers. Upon intravenous administration, the nanoparticles can extravasate through the turbulent blood-joint barrier and access the inflamed joints. In vivo SPECT/CT imaging shows high accumulation in the inflamed joints of mice with RA after intravenous injection of HSP-PEG-NPs with 99mTc labeling (99mTc-HSP-PEG). In vivo therapeutic evaluations suggest that MTX@HSP-PEG-NPs significantly alleviate RA with a high therapeutic index and relatively low adverse systemic toxicities in comparison with free MTX at the same dose. Our study shows that HSP-PEG-NPs could serve as multifunctional vehicles to deliver radioisotopes for in vivo imaging, and MTX for RA treatment, highlighting the innovative development of the nanoparticle-based RA treatment strategy for clinical applications.

Nanomedicines for the treatment of rheumatoid arthritis: State of art and potential therapeutic strategies

Increasing understanding of the pathogenesis of rheumatoid arthritis (RA) has remarkably promoted the development of effective therapeutic regimens of RA. Nevertheless, the inadequate response to current therapies in a proportion of patients, the systemic toxicity accompanied by long-term administration or distribution in non-targeted sites and the comprised efficacy caused by undesirable bioavailability, are still unsettled problems lying across the full remission of RA. So far, these existing limitations have inspired comprehensive academic researches on nanomedicines for RA treatment. A variety of versatile nanocarriers with controllable physicochemical properties, tailorable drug release pattern or active targeting ability were fabricated to enhance the drug delivery efficiency in RA treatment. This review aims to provide an up-to-date progress regarding to RA treatment using nanomedicines in the last 5 years and concisely discuss the potential application of several newly emerged therapeutic strategies such as inducing the antigen-specific tolerance, pro-resolving therapy or regulating the immunometabolism for RA treatments.

Electroactive material-based biosensors for detection and drug delivery

Electroactive materials are employed at the interface of biology and electronics due to their advantageous intrinsic properties as soft organic electronics. We examine the most recent literature of electroactive material-based biosensors and their emerging role as theranostic devices for the delivery of therapeutic agents. We consider electroactive materials through the lens of smart drug delivery systems as materials that enable the release of therapeutic cargo in response to specific physiological and external stimuli and discuss the way these mechanisms are integrated into medical devices with examples of the latest advances. Studies that harness features unique to conductive polymers are emphasized; lastly, we highlight new perspectives and future research direction for this emerging technology and the challenges that remain to overcome.

Novel Bispecific Antibody for Synovial-Specific Target Delivery of Anti-TNF Therapy in Rheumatoid Arthritis

Biologic drugs, especially anti-TNF, are considered as the gold standard therapy in rheumatoid arthritis. However, non-uniform efficacy, incidence of infections, and high costs are major concerns. Novel tissue-specific agents may overcome the current limitations of systemic administration, providing improved potency, and safety. We developed a bispecific antibody (BsAb), combining human arthritic joint targeting, via the synovial-specific single-chain variable fragment (scFv)-A7 antibody, and TNFα neutralization, via the scFv-anti-TNFα of adalimumab, with the binding/blocking capacity comparable to adalimumab -immunoglobulin G (IgG). Tissue-targeting capacity of the BsAb was confirmed on the human arthritic synovium in vitro and in a synovium xenograft Severe combined immune deficient (SCID) mouse model. Peak graft accumulation occurred at 48 h after injection with sustained levels over adalimumab-IgG for 7 days and increased therapeutic effect, efficiently decreasing tissue cellularity, and markers of inflammation with higher potency compared to the standard treatment. This study provides the first description of a BsAb capable of drug delivery, specifically to the disease tissue, and a strong evidence of improved therapeutic effect on the human arthritic synovium, with applications to other existing biologics.

Modulating inflammation through the neutralization of Interleukin-6 and tumor necrosis factor-α by biofunctionalized nanoparticles

Biological agents that neutralize the activity of pro-inflammatory cytokines are revolutionizing the treatment of inflammatory conditions. However, the antibodies (Abs) short half-life and off-target distribution critically limit their efficacy and safety. Therefore, this work proposes the immobilization of anti-TNF-α and anti-IL-6 Abs at the surface of polymeric nanoparticles (NPs) in order to extend and increase the Abs therapeutic efficacy, owing to the protection from degradation that the NPs provide, and to avoid off-target side effects through local administration. In an in vitro model of inflammation, biofunctionalized NPs were able to reduce the harmful effects on human chondrocytes provided by inflammatory macrophages, being demonstrated the additive effects of the dual neutralization. Significantly, biofunctionalized NPs ameliorated inflammation more efficiently than soluble Abs in an in vivo experimental model of inflammation, exhibiting a safe profile, a prolonged action, and a stronger efficacy. Hence, as this strategy is able to increase the therapeutic efficacy of the currently available treatments, it is a promising potential therapeutic option for inflammatory conditions.

The Dual Role of the Liver in Nanomedicine as an Actor in the Elimination of Nanostructures or a Therapeutic Target

The development of nanostructures for therapeutic purpose is rapidly growing, following the results obtained in vivo in animal models and in the clinical trials. Unfortunately, the potential therapeutic efficacy is not completely exploited, yet. This is mainly due to the fast clearance of the nanostructures in the body. Nanoparticles and the liver have a unique interaction because the liver represents one of the major barriers for drug delivery. This interaction becomes even more relevant and complex when the drug delivery strategies employing nanostructures are proposed for the therapy of liver diseases, such as hepatocellular carcinoma (HCC). In this case, the selective delivery of therapeutic nanoparticles to the tumor microenvironment collides with the tendency of nanostructures to be quickly eliminated by the organ. The design of a new therapeutic approach based on nanoparticles to treat HCC has to particularly take into consideration passive and active mechanisms to avoid or delay liver elimination and to specifically address cancer cells or the cancer microenvironment. This review will analyze the different aspects concerning the dual role of the liver, both as an organ carrying out a clearance activity for the nanostructures and as target for therapeutic strategies for HCC treatment.

Active Cellular and Subcellular Targeting of Nanoparticles for Drug Delivery

Nanoparticle (NP)-mediated drug delivery (NMDD) for active targeting of diseases is a primary goal of nanomedicine. NPs have much to offer in overcoming the limitations of traditional drug delivery approaches, including off-target drug toxicity and the need for the administration of repetitive doses. In the last decade, one of the main foci in NMDD has been the realization of NP-mediated drug formulations for active targeted delivery to diseased tissues, with an emphasis on cellular and subcellular targeting. Advances on this front have included the intricate design of targeted NP-drug constructs to navigate through biological barriers, overcome multidrug resistance (MDR), decrease side effects, and improve overall drug efficacy. In this review, we survey advancements in NP-mediated drug targeting over the last five years, highlighting how various NP-drug constructs have been designed to achieve active targeted delivery and improved therapeutic outcomes for critical diseases including cancer, rheumatoid arthritis, and Alzheimer's disease. We conclude with a survey of the current clinical trial landscape for active targeted NP-drug delivery and how we envision this field will progress in the near future.

Intra-articular targeting of nanomaterials for the treatment of osteoarthritis

Osteoarthritis is a prevalent and debilitating disease that involves pathological contributions from numerous joint tissues and cells. The joint is a challenging arena for drug delivery, since the joint has poor bioavailability for systemically administered drugs and experiences rapid clearance of therapeutics after intra-articular injection. Moreover, each tissue within the joint presents unique barriers to drug localization. In this review, the various applications of nanotechnology to overcome these drug delivery limitations are investigated. Nanomaterials have reliably shown improvements to retention profiles of drugs within the joint space relative to injected free drugs. Additionally, nanomaterials have been modified through active and passive targeting strategies to facilitate interactions with and localization within specific joint tissues such as cartilage and synovium. Last, the limitations of drawing cross-study comparisons, the implications of synovial fluid, and the potential importance of multi-modal therapeutic strategies are discussed. As emerging, cell-specific disease modifying osteoarthritis drugs continue to be developed, the need for targeted nanomaterial delivery will likely become critical for effective clinical translation of therapeutics for osteoarthritis. STATEMENT OF SIGNIFICANCE: Improving drug delivery to the joint is a pressing clinical need. Over 27 million Americans live with osteoarthritis, and this figure is continuously expanding. Numerous drugs have been investigated but have failed in clinical trials, likely related to poor bioavailability to target cells. This article comprehensively reviews the advances in nano-scale delivery vehicles designed to overcome the delivery barriers in the joint. This is the first review to analyze active and passive targeting strategies systematically for different target sites while also delineating between tissue homing and whole joint retention. By bringing together the lessons learned across numerous nano-scale platforms, researchers may be able to hone future nanomaterial designs, allowing emerging therapeutics to perform with clinically relevant efficacy and disease modifying potential.

Peptide-targeted liposomal delivery of dexamethasone for arthritis therapy

Aim: Rheumatoid arthritis is an autoimmune disease affecting the joints. Antiarthritic drugs are given systemically, thereby exposing various healthy organs to these drugs, resulting in adverse reactions. Accordingly, there is an urgent need for targeted drug delivery methods for inflamed joints. Materials & methods: We developed a liposomal drug delivery system using a novel peptide ligand (CKPFDRALC) named ART-2, which homes to the inflamed joints when injected intravenously to rats with adjuvant-induced arthritis. Results: The ART-2-coated liposomes encapsulating an antiarthritic drug, dexamethasone (DEX), were more effective in inhibiting arthritis progression than control-DEX liposomes or free DEX, despite a comparable safety profile. Conclusion: Peptide-targeted therapy has advantages over conventional drug delivery and can be adapted for rheumatoid arthritis therapy.

Secreted Protein Acidic and Rich in Cysteine Mediated Biomimetic Delivery of Methotrexate by Albumin-Based Nanomedicines for Rheumatoid Arthritis Therapy

Rheumatoid arthritis (RA) is one of the most common chronic autoimmune diseases. Despite considerable advances in clinical treatment of RA, suboptimal response to therapy and treatment discontinuation are still unresolved challenges due to systemic toxicity. It is of crucial importance to actively target and deliver therapeutic agents to inflamed joints in order to promote in situ activity and decrease systemic toxicity. In this study, we found that SPARC (secreted protein acidic and rich in cysteine) was overexpressed in the synovial fluid and synovium of RA patients as well as mice with collagen-induced arthritis (CIA), which has been scarcely reported. Building upon the SPARC signature of RA joint microenvironment and the intrinsic high affinity of SPARC for albumin, we fabricated methotrexate-loaded human serum albumin nanomedicines (MTX@HSA NMs) and explored them as biomimetic drug delivery systems for RA therapy. Upon intravenous injection of chlorin e6-labeled MTX@HSA NMs into CIA mice, the fluorescence/magnetic resonance dual-modal imaging revealed higher accumulations and longer retention of MTX@HSA NMs in inflamed joints with respect to free MTX molecules. In vivo therapeutic evaluations suggested that the MTX@HSA NMs were able to attenuate the progression of RA with better efficacy and fewer side effects even at half  dose of administrated MTX in comparison with free MTX. By unraveling the mechanism driving the efficient accumulation of MTX@HSA NMs in RA joints and showing their ability to improve the safety and therapeutic efficacy of MTX, our work sheds light on the development of innovative anti-RA nanomedicines with a strong potential for clinical translation.

IL-17 in Rheumatoid Arthritis and Precision Medicine: From Synovitis Expression to Circulating Bioactive Levels

Interleukin (IL)-17A has a direct contribution in early induction and late chronic stages of various inflammatory diseases. In vitro and in vivo experiments have first characterized its local effects on different cell types and then its systemic effects. For instance, IL-17 axis is now identified as a key driver of psoriasis through its effects on keratinocytes. Similar observations apply for rheumatoid arthritis (RA) where IL-17A triggers changes in the synovium that lead to synovitis and maintain local inflammation. These results have prompted the development of biologics to target this cytokine. However, while convincing studies are reported on the efficacy of IL-17 inhibitors in psoriasis, there are conflicting results in RA. Patient heterogeneity but also the involvement of mediators that regulate IL-17 function may explain these results. Therefore, new tools and concepts are required to identify patients that could benefit from these IL-17 targeted therapies in RA and the development of predictive biomarkers of response has started with the emergence of various bioassays. Current strategies are also focusing on synovial biopsies that may be used to stratify patients. From local to systemic levels, new approaches are developing and move the field of RA management into the era of precision medicine.

Nanoparticle Properties for Delivery to Cartilage: The Implications of Disease State, Synovial Fluid, and Off-Target Uptake

A major hurdle limiting the ability to treat and cure osteoarthritis, a common and debilitating disease, is rapid joint clearance and limited cartilage targeting of intra-articular therapies. Nanoscale drug carriers have the potential to improve therapeutic targeting and retention in the joint after direct injection; however, there still lacks a fundamental understanding of how the physicochemical properties of nanoparticles (NPs) influence localization to the degenerating cartilage and how joint conditions such as disease state and synovial fluid impact NP biodistribution. The goal of this study was to assess how physicochemical properties of NPs influence their interactions with joint tissues and, ultimately, cartilage localization. Ex vivo models of joint tissues were used to study how poly(lactide- co-glycolide) (PLGA) and polystyrene (PS) NP size, charge, and surface chemistry influence cartilage retention under normal and disease-mimicking conditions. Of the particles investigated, PLGA NPs surface-modified with a quaternary ammonium cation had the greatest retention within cartilage explants; however, retention was diminished 2- to 2.9-fold in arthritic tissue and in the presence of synovial fluid. Interactions with synovial fluid induced changes to NP surface properties and colloidal stability in vitro. The impact of NP charge on "off-target" synoviocyte uptake was also dependent on synovial fluid interactions. The results suggest that the design of nanocarriers for targeted drug delivery within the joint cannot be based on a single parameter such as zeta potential or size, and that the fate of injected delivery systems will likely be influenced by the disease state of the joint and the presence of synovial fluid.

Emergent nanotherapies in microcrystal-induced arthritis

The anti-inflammatory and immunomodulatory effects of nanoparticles in several chronic diseases have been extensively researched. The aim of this review is to examine how nanoparticles modulate the inflammatory pathways that characterize the most prevalent forms of microcrystal-induced arthritis, including gout, pseudogout, and BCP-induced arthritis. The nanoparticles of chitosan-coated calcium phosphate, uricase, aceclofenac, and gold have been investigated in crystal-inducedarthritis. The most important results of the studies outlined in this review show that nanoparticles can inhibit the expression and the release of some pro-inflammatory mediators and proteolytic enzymes, and the activity of different transcriptional factors in vitro, as well as decrease the uric acid levels in several studies of in vitro and in vivo models of gout, which show interesting results in terms of decreasing the amount of crystals and tissue damage, respectively. In view of their multiple beneficial effects, nanoparticles can be considered a valuable therapy that contributes to the pharmacological treatment in crystalinduced arthritis.

Synovial fibroblast-targeting liposomes encapsulating an NF-κB-blocking peptide ameliorates zymosan-induced synovial inflammation

Synovial fibroblasts (SFs) play a crucial role in the inflammatory process of rheumatoid arthritis (RA). The highly activated NF‐κB signal in SFs is responsible for most of the synovial inflammation associated with this disease. In this study, we have developed an SF‐targeting liposomal system that encapsulates the NF‐κB‐blocking peptide (NBD peptide) HAP‐lipo/NBD. HAP‐lipo/NBDs demonstrated efficient SF‐specific targeting in vitro and in vivo. Our study also showed a significant inhibitory effect of HAP‐lipo/NBD on NF‐κB activation, inflammatory cytokine release and SF migration capability after zymosan stimulation. Furthermore, the systemic administration of HAP‐lipo/NBDs significantly inhibited synovial inflammation and improved the pathological scores of arthritis induced by zymosan. Thus, these results suggest that an SF‐targeting NF‐κB‐blocking strategy is a potential approach for the development of alternative, targeted anti‐RA therapies.

Role of TrkA signalling and mast cells in the initiation of osteoarthritis pain in the monoiodoacetate model

OBJECTIVE

Aiming to delineate novel neuro-immune mechanisms for NGF/TrkA signalling in osteoarthritis (OA) pain, we evaluated inflammatory changes in the knee joints following injection of monoiodoacetate (MIA) in mice carrying a TrkA receptor mutation (P782S; TrkA KI mice).

METHOD

In behavioural studies we monitored mechanical hypersensitivity following intra-articular MIA and oral prostaglandin D₂ (PGD₂) synthase inhibitor treatments. In immunohistochemical studies we quantified joint mast cell numbers, calcitonin gene-related peptide expression in synovia and dorsal root ganglia, spinal cord neuron activation and microgliosis. We quantified joint leukocyte infiltration by flow cytometry analysis, and PGD₂ generation and cyclooxygenase-2 (COX-2) expression in mast cell lines by ELISA and Western blot.

RESULTS

In TrkA KI mice we observed rapid development of mechanical hypersensitivity and amplification of dorsal horn neurons and microglia activation 7 days after MIA. In TrkA KI knee joints we detected significant leukocyte infiltration and mast cells located in the vicinity of synovial nociceptive fibres. We demonstrated that mast cells exposure to NGF results in up-regulation of COX-2 and increase of PGD₂ production. Finally, we observed that a PGD₂ synthase inhibitor prevented MIA-mechanical hypersensitivity in TrkA KI, at doses which were ineffective in wild type (WT) mice.

CONCLUSION

Using the TrkA KI mouse model, we delineated a novel neuro-immune pathway and suggest that NGF-induced production of PGD₂ in joint mast cells is critical for referred mechanical hypersensitivity in OA, probably through the activation of PGD₂ receptor 1 in nociceptors: TrkA blockade in mast cells constitutes a potential target for OA pain.

Targeting Anti-TGF-β Therapy to Fibrotic Kidneys with a Dual Specificity Antibody Approach

Targeted delivery of a therapeutic agent to a site of pathology to ameliorate disease while limiting exposure at undesired tissues is an aspirational treatment scenario. Targeting diseased kidneys for pharmacologic treatment has had limited success. We designed an approach to target an extracellular matrix protein, the fibronectin extra domain A isoform (FnEDA), which is relatively restricted in distribution to sites of tissue injury. In a mouse unilateral ureteral obstruction (UUO) model of renal fibrosis, injury induced significant upregulation of FnEDA in the obstructed kidney. Using dual variable domain Ig (DVD-Ig) technology, we constructed a molecule with a moiety to target FnEDA and a second moiety to neutralize TGF-β After systemic injection of the bispecific TGF-β + FnEDA DVD-Ig or an FnEDA mAb, chemiluminescent detection and imaging with whole-body single-photon emission computed tomography (SPECT) revealed significantly higher levels of each molecule in the obstructed kidney than in the nonobstructed kidney, the ipsilateral kidney of sham animals, and other tissues. In comparison, a systemically administered TGF-β mAb accumulated at lower concentrations in the obstructed kidney and exhibited a more diffuse whole-body distribution. Systemic administration of the bispecific DVD-Ig or the TGF-β mAb (1-10 mg/kg) but not the FnEDA mAb attenuated the injury-induced collagen deposition detected by immunohistochemistry and elevation in Col1a1, FnEDA, and TIMP1 mRNA expression in the obstructed kidney. Overall, systemic delivery of a bispecific molecule targeting an extracellular matrix protein and delivering a TGF-β mAb resulted in a relatively focal uptake in the fibrotic kidney and reduced renal fibrosis.

New structural formats of therapeutic antibodies for rheumatology

Pharmaceutical companies strive continuously to develop better medications in order to remain competitive. In the arena of monoclonal antibodies and related biologics (fusion proteins containing an IgG Fc fragment), the thrust is not only toward identifying new targets, but also toward developing new molecular formats. Here, new-generation antibodies used to treat rheumatic diseases are discussed, with emphasis on relations linking structure to pharmacological effects and on the improvements expected from the new formats. Isotypic and allotypic antibody diversity has pharmacological implications and is already exploited in commercially available antibodies. Efforts to engineer the Fc fragment of the various immunoglobulin G subclasses are reviewed with reference to abatacept, ixekizumab, other mutated IgG4 antibodies currently in development, sapelizumab, anifrolumab, and tanezumab. Bispecific antibodies are a focus of increasing interest (particularly those binding to both IL-17 and TNFα) and may earn a place in the therapeutic armamentarium as a means of avoiding the use of antibody combinations. However, the construction and production of bispecific antibodies continues to raise major technological challenges. Other molecular formats involve the fusion of antibodies to cytokines or the use of nanobodies and peptibodies. These new formats are at the very early stages of development, and their clinical relevance remains unclear.

The effects of TGF-βs on immune responses

Transforming growth factor (TGF)-β family is a cytokine family with various biological processes and forms a highly homologous group of three mammalian isoforms, TGF-β1, TGF-β2, and TGF-β3. Most of the attention on TGF-β family in immunology has been mainly focused on TGF-β1 in that TGF-β1 induces anti-inflammatory regulatory T cells (Treg), and inflammatory T helper 17 (Th17) cells in combination with interleukin-6. Although little attention has been focused on the immunological roles of TGF-β2 and TGF-β3, the function of TGF-β3 for maintaining immunological homeostasis has recently been identified such as the induction of Th17 cells and direct regulatory effects on humoral immunity. TGF-β1 and TGF-β3 shares similar anti-inflammatory or pro-inflammatory functions, but exhibits significantly different effects on fibrosis and chondrogenesis. For the clinical application of TGF-βs, the mechanisms by which each TGF-β isoform regulates immunity has to be elucidated. In this review, we provide an overview of the effects, cellular targets, and therapeutic potential of TGF-βs on immune responses and autoimmune diseases.

Tocilizumab-Alendronate Conjugate for Treatment of Rheumatoid Arthritis

An autoimmune disease of rheumatoid arthritis (RA) causes severe inflammation on the synovial membrane, which results in the destruction of articular cartilage and bone. Here, Tocilizumab (TCZ)-Alendronate (ALD) conjugate is synthesized for the early intervention of RA. A humanized monoclonal antibody of TCZ shows an immunosuppressive effect, targeting interleukin-6 (IL-6) receptor in the RA pathogenesis. ALD is an anti-inflammatory bisphosphonate drug which can bind to the exposed bone surface. ALD is conjugated selectively to N-glycan on Fc region of TCZ using a chemical linker of 3-(2-pyridyldithio)propionyl hydrazide (PDPH)-poly(ethylene glycol)-N-hydroxysuccinimide (PDPH-PEG-NHS). The successful synthesis of TCZ-ALD conjugate is corroborated by ¹H NMR, the purpald assay, mass spectrometry (MS), and high performance liquid chromatography (HPLC). In vitro binding affinity and cell viability tests confirmed the biological activity of TCZ-ALD conjugate. Furthermore, in vivo efficacy of TCZ-ALD conjugate is confirmed by microcomputed tomography (CT), histology, and Western blot analyses for the treatment of RA.

Ectopic lymphoid neogenesis in rheumatic autoimmune diseases

Ectopic lymphoid neogenesis often occurs in the target tissues of patients with chronic rheumatic autoimmune diseases such as rheumatoid arthritis, Sjögren syndrome and other connective tissue disorders, including systemic lupus erythematosus and myositis. However, the mechanisms of ectopic lymphoid-like structure (ELS) formation and function are not entirely understood. For example, it is unclear whether ELSs indicate distinct disease phenotypes or whether they are evolutionary manifestations of chronic inflammation. Also unclear is why ELSs form in some patients but not in others. Nonetheless, ELSs frequently display functional features of ectopic germinal centres and can actively contribute to the maintenance of autoimmunity through the production of disease-specific autoantibodies; furthermore, they seem to influence disease severity and response to both synthetic and biologic DMARDs. In this Review, we discuss current knowledge and gaps in understanding of ELS formation and function including their prevalence in the above rheumatic autoimmune diseases; the mechanisms underlying their formation, maintenance and function, including positive and negative regulatory pathways; their functional relevance in the perpetuation of autoimmunity; their relationship with disease phenotypes, clinical outcomes and response to treatment; and the potential for specific targeting of ELSs through novel therapeutic modalities.

Leveraging Physiology for Precision Drug Delivery

Physiological characteristics of diseases bring about both challenges and opportunities for targeted drug delivery. Various drug delivery platforms have been devised ranging from macro- to micro- and further into the nanoscopic scale in the past decades. Recently, the favorable physicochemical properties of nanomaterials, including long circulation, robust tissue and cell penetration attract broad interest, leading to extensive studies for therapeutic benefits. Accumulated knowledge about the physiological barriers that affect the in vivo fate of nanomedicine has led to more rational guidelines for tailoring the nanocarriers, such as size, shape, charge, and surface ligands. Meanwhile, progresses in material chemistry and molecular pharmaceutics generate a panel of physiological stimuli-responsive modules that are equipped into the formulations to prepare “smart” drug delivery systems. The capability of harnessing physiological traits of diseased tissues to control the accumulation of or drug release from nanomedicine has further improved the controlled drug release profiles with a precise manner. Successful clinical translation of a few nano-formulations has excited the collaborative efforts from the research community, pharmaceutical industry, and the public towards a promising future of smart drug delivery.

Recent advances in nanomedicines for the treatment of rheumatoid arthritis

Schematic illustration of inflammatory microenvironment in inflamed joints and events occurring in rheumatoid arthritis.

Novel synthetic (E)-2-methoxy-4-(3-(4-methoxyphenyl) prop-1-en-1-yl) phenol inhibits arthritis by targeting signal transducer and activator of transcription 3

Rheumatoid arthritis (RA) is a severely debilitating chronic autoimmune disease that leads to long-term joint damage. Signal transducer and activator of transcription 3 (STAT3)-targeted small molecules have shown promise as therapeutic drugs for treating RA. We previously identified (E)-2,4-bis(p-hydroxyphenyl)-2-butenal (BHPB), a tyrosine-fructose Maillard reaction product, as a small molecule with potent anti-inflammatory and anti-arthritic properties, mediated through the inhibition of STAT3 activation. The aim of this study was to develop a novel BHPH derivative with improved anti-arthritic properties and drug-likeness. We designed and synthesised (E)-2-methoxy-4-(3-(4-methoxyphenyl) prop-1-en-1-yl) phenol (MMPP), a novel synthetic BHPB analogue, and investigated its anti-inflammatory and anti-arthritic activities in experimentally-induced RA. We showed that MMPP strongly inhibited pro-inflammatory responses by inhibiting in vitro STAT3 activation and its downstream signalling in murine macrophages and human synoviocytes from patients with RA. Furthermore, we demonstrated that MMPP exhibited potent anti-arthritic activity in a collagen antibody-induced arthritis (CAIA) mouse model in vivo. Collectively, our results suggest that MMPP has great potential for use in the treatment of RA.

Adding Functions to Biomaterial Surfaces through Protein Incorporation

The concept of biomaterials has evolved from one of inert mechanical supports with a long-term, biologically inactive role in the body into complex matrices that exhibit selective cell binding, promote proliferation and matrix production, and may ultimately become replaced by newly generated tissues in vivo. Functionalization of material surfaces with biomolecules is critical to their ability to evade immunorecognition, interact productively with surrounding tissues and extracellular matrix, and avoid bacterial colonization. Antibody molecules and their derived fragments are commonly immobilized on materials to mediate coating with specific cell types in fields such as stent endothelialization and drug delivery. The incorporation of growth factors into biomaterials has found application in promoting and accelerating bone formation in osteogenerative and related applications. Peptides and extracellular matrix proteins can impart biomolecule- and cell-specificities to materials while antimicrobial peptides have found roles in preventing biofilm formation on devices and implants. In this progress report, we detail developments in the use of diverse proteins and peptides to modify the surfaces of hard biomaterials in vivo and in vitro. Chemical approaches to immobilizing active biomolecules are presented, as well as platform technologies for isolation or generation of natural or synthetic molecules suitable for biomaterial functionalization.

Rational design of antirheumatic prodrugs specific for sites of inflammation

Objective

Biologic drugs, such as the anti–tumor necrosis factor (anti‐TNF) antibody adalimumab, have represented a breakthrough in the treatment of rheumatoid arthritis. Yet, concerns remain over their lack of efficacy in a sizable proportion of patients and their potential for systemic side effects such as infection. Improved biologic prodrugs specifically targeted to the site of inflammation have the potential to alleviate current concerns surrounding biologic anticytokine therapies. The purpose of this study was to design, construct, and evaluate in vitro and ex vivo the targeting and antiinflammatory capacity of activatable bispecific antibodies.

Methods

Activatable dual variable domain (aDVD) antibodies were designed and constructed to target intercellular adhesion molecule 1 (ICAM‐1), which is up‐regulated at sites of inflammation, and anti‐TNF antibodies (adalimumab and infliximab). These bispecific molecules included an external arm that targets ICAM‐1 and an internal arm that comprises the therapeutic domain of an anti‐TNF antibody. Both arms were linked to matrix metalloproteinase (MMP)–cleavable linkers. The constructs were tested for their ability to bind and neutralize both in vitro and ex vivo targets.

Results

Intact aDVD constructs demonstrated significantly reduced binding and anti‐TNF activity in the prodrug formulation as compared to the parent antibodies. Human synovial fluid and physiologic concentrations of MMP enzyme were capable of cleaving the external domain of the antibody, revealing a fully active molecule. Activated antibodies retained the same binding and anti‐TNF inhibitory capacities as the parent molecules.

Conclusion

The design of a biologic prodrug with enhanced specificity for sites of inflammation (synovium) and reduced specificity for off‐target TNF is described. This construct has the potential to form a platform technology that is capable of enhancing the therapeutic index of drugs for the treatment of RA and other inflammatory diseases.

The impact of nanoparticle protein corona on cytotoxicity, immunotoxicity and target drug delivery

In a perfect sequence of events, nanoparticles (NPs) are injected into the bloodstream where they circulate until they reach the target tissue. The ligand on the NP surface recognizes its specific receptor expressed on the target tissue and the drug is released in a controlled manner. However, once injected in a physiological environment, NPs interact with biological components and are surrounded by a protein corona (PC). This can trigger an immune response and affect NP toxicity and targeting capabilities. In this review, we provide a survey of recent findings on the NP-PC interactions and discuss how the PC can be used to modulate both cytotoxicity and the immune response as well as to improve the efficacy of targeted delivery of nanocarriers.

Hypoxia-responsive nanocarriers for cancer imaging and therapy: recent approaches and future perspectives

This review focuses on hypoxia-responsive nanocarriers, which can be disintegrated by recognizing the hypoxic microenvironment of cancer cells, and their utilization in cancer imaging and therapy.

Therapeutic potential of regulatory cytokines that target B cells

Autoreactive B cells play a crucial role in the pathogenesis of autoimmune diseases by producing auto-antibodies and presenting antigens. Regulatory cytokines that simultaneously suppress multiple pathways have the potential to control autoreactive B cells. The generally inhibitory cytokine IL-10 may have a stimulatory effect on human B-cell survival and antibody production. TGF-β family cytokines can decrease or increase antibody production and can suppress B-cell proliferation and differentiation. In contrast to TGF-β1, which induces extensive fibrosis, TGF-β3 and bone morphogenetic protein 6 (BMP-6)/BMP-7 induce non-scarring wound healing and counteract tissue fibrosis. Therefore, TGF-β3 and BMP-6/BMP-7 may be clinically applicable as therapeutic cytokines that target B cells. Recent progress in protein engineering may enable us to generate novel biologic therapies based on TGF-β family cytokines.

Going with the flow: harnessing the power of the vasculature for targeted therapy in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic, systemic, autoimmune disease that leads to excessive joint inflammation and is associated with significant morbidity and mortality. Although much is still to be learned about the aetiology RA, a growing body of evidence suggests that an altered vascular environment is an important aspect of its pathophysiology. In this context, RA shares many similarities with cancer, and it is expected that several angiogenic targets in cancer might be relevant to the treatment of RA. Here, we discuss how these targets can be combined with advances in drug development to generate the next generation of RA therapeutics.

Treatment of rheumatoid arthritis: Unraveling the conundrum

Rheumatoid arthritis (RA) is a heterogeneous disease with a complex and yet not fully understood pathophysiology, where numerous different cell-types contribute to a destructive process of the joints. This complexity results into a considerable interpatient variability in clinical course and severity, which may additionally involve genetics and/or environmental factors. After three decades of focused efforts scientists have now achieved to apply in clinical practice, for patients with RA, the "treat to target" approach with initiation of aggressive therapy soon after diagnosis and escalation of the therapy in pursuit of clinical remission. In addition to the conventional synthetic disease modifying anti-rheumatic drugs, biologics have greatly improved the management of RA, demonstrating efficacy and safety in alleviating symptoms, inhibiting bone erosion, and preventing loss of function. Nonetheless, despite the plethora of therapeutic options and their combinations, unmet therapeutic needs in RA remain, as current therapies sometimes fail or produce only partial responses and/or develop unwanted side-effects. Unfortunately the mechanisms of 'nonresponse' remain unknown and most probable lie in the unrevealed heterogeneity of the RA pathophysiology. In this review, through the effort of unraveling the complex pathophysiological pathways, we will depict drugs used throughout the years for the treatment of RA, the current and future biological therapies and their molecular or cellular targets and finally will suggest therapeutic algorithms for RA management. With multiple biologic options, there is still a need for strong predictive biomarkers to determine which drug is most likely to be effective, safe, and durable in a given individual. The fact that available biologics are not effective in all patients attests to the heterogeneity of RA, yet over the long term, as research and treatment become more aggressive, efficacy, toxicity, and costs must be balanced within the therapeutic equation to enhance the quality of life in patients with RA.

Rheumatoid arthritis-celiac disease relationship: joints get that gut feeling

Rheumatoid arthritis (RA) and celiac disease (CD) belong to the autoimmune disease family. Despite being separate entities they share multiple aspects. Epidemiologically they share comparable incidence environmental influences, associated antibodies and a recent incidental surge. They differ in their HLA pre-dispositions and specific predictive and diagnostic biomarkers. At the clinical level, celiac disease exhibits extra-intestinal rheumatic manifestations and RA gastrointestinal ones. Small bowel pathology exists in rheumatic patients. A trend towards responsiveness to a gluten free diet has been observed, ameliorating celiac rheumatic manifestations, whereas dietary interventions for rheumatoid arthritis remain controversial. Pathophysiologically, both diseases are mediated by endogenous enzymes in the target organs. The infectious, dysbiotic and increased intestinal permeability theories, as drivers of the autoimmune cascade, apply to both diseases. Contrary to their specific HLA pre-disposition, the diseases share multiple non-HLA loci. Those genes are crucial for activation and regulation of adaptive and innate immunity. Recently, light was shed on the interaction between host genetics and microbiota composition in relation to CD and RA susceptibility, connecting bugs and us and autoimmunity. A better understanding of the above mentioned similarities in the gut-joint inter-relationship, may elucidate additional facets in the mosaic of autoimmunity, relating CD to RA.