Early diagnosis of arthritis in mice with collagen-induced arthritis, using a fluorogenic matrix metalloproteinase 3-specific polymeric probe

A Metabolic Driven Bio-Responsive Hydrogel Loading Psoralen for Therapy of Rheumatoid Arthritis

Overexpressed matrix metalloproteinases, hypoxia microenvironment, and metabolic abnormality are important pathological signs of rheumatoid arthritis (RA). Designing a delivery carrier according to the pathological characteristics of RA that can control drug release in response to disease severity may be a promising treatment strategy. Psoralen is the main active ingredient isolated from Psoralea corylifolia L. and possesses excellent anti-inflammatory activities as well as improving bone homeostasis. However, the specific underlying mechanisms, particularly the possible relationships between the anti-RA effects of psoralen and related metabolic network, remain largely unexplored. Furthermore, psoralen shows systemic side effects and has unsatisfactory solubility. Therefore, it is desirable to develop a novel delivery system to maximize psoralen's therapeutic effect. In this study, a self-assembled degradable hydrogel platform is developed that delivers psoralen and calcium peroxide to arthritic joints and controls the release of psoralen and oxygen according to inflammatory stimulation, to regulate homeostasis and the metabolic disorder of the anoxic arthritic microenvironment. Therefore, the hydrogel drug delivery system based on the responsiveness of the inflammatory microenvironment and regulation of metabolism provides a new therapeutic strategy for RA treatment.

Design of Smart Size-, Surface-, and Shape-Switching Nanoparticles to Improve Therapeutic Efficacy

Multiple biological barriers must be considered in the design of nanomedicines, including prolonged blood circulation, efficient accumulation at the target site, effective penetration into the target tissue, selective uptake of the nanoparticles into target cells, and successful endosomal escape. However, different particle sizes, surface chemistries, and sometimes shapes are required to achieve the desired transport properties at each step of the delivery process. In response, this review highlights recent developments in the design of switchable nanoparticles whose size, surface chemistry, shape, or a combination thereof can be altered as a function of time, a disease-specific microenvironment, and/or via an externally applied stimulus to enable improved optimization of nanoparticle properties in each step of the delivery process. The practical use of such nanoparticles in chemotherapy, bioimaging, photothermal therapy, and other applications is also discussed.

Molecular Imaging of Inflammatory Disease

Inflammatory diseases include a wide variety of highly prevalent conditions with high mortality rates in severe cases ranging from cardiovascular disease, to rheumatoid arthritis, to chronic obstructive pulmonary disease, to graft vs. host disease, to a number of gastrointestinal disorders. Many diseases that are not considered inflammatory per se are associated with varying levels of inflammation. Imaging of the immune system and inflammatory response is of interest as it can give insight into disease progression and severity. Clinical imaging technologies such as computed tomography (CT) and magnetic resonance imaging (MRI) are traditionally limited to the visualization of anatomical information; then, the presence or absence of an inflammatory state must be inferred from the structural abnormalities. Improvement in available contrast agents has made it possible to obtain functional information as well as anatomical. In vivo imaging of inflammation ultimately facilitates an improved accuracy of diagnostics and monitoring of patients to allow for better patient care. Highly specific molecular imaging of inflammatory biomarkers allows for earlier diagnosis to prevent irreversible damage. Advancements in imaging instruments, targeted tracers, and contrast agents represent a rapidly growing area of preclinical research with the hopes of quick translation to the clinic.

Tocilizumab-Conjugated Polymer Nanoparticles for NIR-II Photoacoustic-Imaging-Guided Therapy of Rheumatoid Arthritis

The progressive debilitating nature of rheumatoid arthritis (RA) combined with its unknown etiology and initial similarity to other inflammatory diseases makes early diagnosis a significant challenge. Early recognition and treatment of RA is essential for achieving effective therapeutic outcome. NIR-II photoacoustic (PA) molecular imaging (PMI) is emerging as a promising new strategy for effective diagnosis and treatment guidance of RA, owing to its high sensitivity and specificity at large penetration depth. Herein, an antirheumatic targeted drug tocilizumab (TCZ) is conjugated to polymer nanoparticles (PNPs) to develop the first NIR-II theranostic nanoplatform, named TCZ-PNPs, for PA-imaging-guided therapy of RA. The TCZ-PNPs are demonstrated to have strong NIR-II extinction coefficient, high photostability and excellent biocompatibility. NIR-II PMI results reveal the excellent targeting abilities of TCZ-PNPs for the effective noninvasive diagnosis of RA joint tissue with a high signal-to noise ratio (SNR) of 35.8 dB in 3D PA tomography images. Remarkably, one-month treatment and PA monitoring using TCZ-PNPs shows RA is significantly suppressed. In addition, the therapeutic evaluation of RA mice by NIR-II PMI is shown to be consistent with clinical micro-CT and histological analysis. The TCZ-PNPs-assisted NIR-II PMI provides a new strategy for RA theranostics, therapeutic monitoring and the beyond.

Paradigms in Fluorescence Molecular Imaging: Maximizing Measurement of Biological Changes in Disease, Therapeutic Efficacy, and Toxicology/Safety

Fluorescence molecular imaging (MI) is an important concept in preclinical research that focuses on the visualization of cellular and biological function in a non-invasive fashion to better understand in vivo disease processes and treatment effects. MI differs fundamentally from traditional preclinical imaging strategies in that it generally relies on reporter probes specific for particular targets or pathways that can be used to reveal biological changes in situ, at the site(s) of disease. In contrast, the more established imaging modalities, like magnetic resonance imaging, X-ray, micro X-ray computed tomography, and ultrasound, historically have relied primarily on late-stage anatomical or physiologic changes. The practical application of fluorescence MI, however, has drifted somewhat from the emphasis on quantifying biology, and based on the publication record, it now appears to include any imaging in which a probe or contrast agent is used to non-invasively acquire in vivo endpoint information. Unfortunately, the mere use of a defined biologically specific probe, in the absence of careful study design, does not guarantee that any useful biological information is actually gained, although often useful endpoint results still can be achieved. This review proposes to add subcategories of MI, termed MI biological assessment (or MIBA), that emphasize a focus on obtaining early and clear biological changes associated with disease development, therapeutic efficacy, and drug-induced tissue changes. Proper selection of probes and careful study design are critical for maximizing the non-invasive assessment of in vivo biological changes, and applications of these critical elements are described.

Stimuli-responsive Drug Delivery Systems as an Emerging Platform for Treatment of Rheumatoid Arthritis

Rheumatoid Arthritis (RA) is a systemic autoimmune disease accompanied by chronic inflammation. Due to the long-term infiltration in inflammatory sites, joints get steadily deteriorated, eventually resulting in functional incapacitation and disability. Despite the considerable effect, RA sufferers treated with current drug therapeutic efficacy are exposed to severe side effects. Application of Drug Delivery Systems (DDS) has improved these situations while the problem of limited drug exposure remains untackled. Stimuli-responsive DDS that are responsive to a variety of endogenous and exogenous stimuli, such as pH, redox status, and temperature, have emerged as a promising therapeutic strategy to optimize the drug release. Herein, we discussed the therapeutic regimes and serious side effects of current RA therapy, as well as focused on some of the potential stimuliresponsive DDS utilized in RA therapy. Besides, the prospective room in designing DDS for RA treatment has also been discussed.

Oral and Subcutaneous Administration of a Near-Infrared Fluorescent Molecular Imaging Agent Detects Inflammation in a Mouse Model of Rheumatoid Arthritis

Rheumatoid arthritis (RA) is an inflammatory autoimmune disease that causes irreversible damage to the joints. However, effective drugs exist that can stop disease progression, leading to intense interest in early detection and treatment monitoring to improve patient outcomes. Imaging approaches have the potential for early detection, but current methods lack sensitivity and/or are time-consuming and expensive. We examined potential routes for self-administration of molecular imaging agents in the form of subcutaneous and oral delivery of an integrin binding near-infrared (NIR) fluorescent imaging agent in an animal model of RA with the long-term goal of increasing safety and patient compliance for screening. NIR imaging has relatively low cost, uses non-ionizing radiation, and provides minimally invasive spatial and molecular information. This proof-of-principle study shows significant uptake of an IRDye800CW agent in inflamed joints of a collagen antibody induced arthritis (CAIA) mouse model compared to healthy joints, irrespective of the method of administration. The imaging results were extrapolated to clinical depths in silico using a 3D COMSOL model of NIR fluorescence imaging in a human hand to examine imaging feasability. With target to background concentration ratios greater than 5.5, which are achieved in the mouse model, these probes have the potential to identify arthritic joints following oral delivery at clinically relevant depths.

Effect of methotrexate on collagen-induced arthritis in male Wistar rats

To evaluate the effect of methotrexate on collagen-induced arthritis, micro-computed tomography (micro-CT) and histopathological analyses were used in male Wistar rats. Rats were divided randomly into three groups. Group 1 was treated with 0.9% saline, and groups 2 and 3 were boosted with type Ⅱ collagen. From day 21 to 42, groups 1 and 2 were orally treated with 0.9% saline and group 3 was orally treated with 1.5 mg/kg methotrexate. All rats were sacrificed at day 42 after the first collagen treatment. Micro-CT analyses showed bony parameters, such as bone volume and trabecular number, were decreased in group 2 compared to group 1, and these parameters were recovered in group 3. Histopathological examination and pathological parameter scoring showed that the knee joints of rats in group 2 had severe joint destruction, showing cartilage and bone erosion, enlarged cavities with inflammatory cell infiltration and activation of synovial fibroblasts. By contrast, these changes were reduced in group 3. Taken together, methotrexate treatment showed therapeutic potential in male rat collagen-induced arthritis model, and micro-CT analysis and histopathological tools could be integrated to assess the quantification/qualification of arthritic lesions.

Applications of nanoparticles in biomedical imaging

An urgent need for early detection and diagnosis of diseases continuously pushes the advancements of imaging modalities and contrast agents. Current challenges remain for fast and detailed imaging of tissue microstructures and lesion characterization that could be achieved via development of nontoxic contrast agents with longer circulation time. Nanoparticle technology offers this possibility. Here, we review nanoparticle-based contrast agents employed in most common biomedical imaging modalities, including fluorescence imaging, MRI, CT, US, PET and SPECT, addressing their structure related features, advantages and limitations. Furthermore, their applications in each imaging modality are also reviewed using commonly studied examples. Future research will investigate multifunctional nanoplatforms to address safety, efficacy and theranostic capabilities. Nanoparticles as imaging contrast agents have promise to greatly benefit clinical practice.

Recent advances in nanomedicines for the treatment of rheumatoid arthritis

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

Assessment of murine collagen-induced arthritis by longitudinal non-invasive duplexed molecular optical imaging

OBJECTIVE

In the present study we evaluated the use of four commercially available fluorescent probes to monitor disease activity in murine CIA and its suppression during glucocorticoid therapy.

METHODS

Arthritis was induced in male DBA/1 mice by immunization with type II collagen in Complete Freund's Adjuvant, followed by a boost of collagen in PBS. Four fluorescent probes from PerkinElmer in combination [ProSense 750 fluorescent activatable sensor technology (FAST) with Neutrophil Elastase 680 FAST and MMPSense 750 FAST with CatK 680 FAST] were used to monitor disease development from day 5 through to day 40 post-immunization. Fluorescence generated in vivo by the probes was correlated with clinical and histological score and paw measurements.

RESULTS

The fluorescence intensity emitted by each probe was shown to correlate with the conventional measurements of disease. The highest degree of correlation was observed with ProSense 750 FAST in combination with Neutrophil Elastase 680 FAST; these probes were then used to successfully assess CIA suppression during dexamethasone treatment.

CONCLUSION

We have demonstrated that longitudinal non-invasive duplexed optical fluorescence imaging provides a simple assessment of arthritic disease activity within the joints of mice following the induction of CIA and may represent a powerful tool to monitor the efficacy of drug treatments in preclinical studies.

Analysis of the trajectory of osteoarthritis development in a mouse model by serial near-infrared fluorescence imaging of matrix metalloproteinase activities

OBJECTIVE

A major hurdle in osteoarthritis (OA) research is the lack of sensitive detection and monitoring methods. It is hypothesized that proteases, such as matrix metalloproteinases (MMPs), are up-regulated in the early stages of OA development. This study was undertaken to investigate if a near-infrared (NIR) fluorescent probe activated by MMPs could visualize in vivo OA progression beginning in the early stages of the disease.

METHODS

Using an MMP-activatable NIR fluorescent probe (MMPSense 680), we assessed the up-regulation of MMP activity in vitro by incubating human chondrocytes with the proinflammatory cytokine interleukin-1β (IL-1β). MMP activity was then evaluated in vivo serially in a mouse model of chronic, injury-induced OA. To track MMP activity over time, mice were imaged 1-8 weeks after OA-inducing surgery. Imaging results were correlated with histologic findings.

RESULTS

In vitro studies confirmed that NIR fluorescence imaging identified enhanced MMP activity in IL-1β-treated human chondrocytes. In vivo imaging showed significantly higher fluorescence intensity in OA knees compared to sham-operated (control) knees of the same mice. Additionally, the total emitted fluorescence intensity steadily increased over the entire course of OA progression that was examined. NIR fluorescence imaging results correlated with histologic findings, which showed an increase in articular cartilage structural damage over time.

CONCLUSION

Imaging of MMP activity in a mouse model of OA provides sensitive and consistent visualization of OA progression, beginning in the early stages of OA. In addition to facilitating the preclinical study of OA modulators, this approach has the potential for future translation to humans.

99mTc-NTP 15-5 Imaging for Cartilage Involvement in Experimental Rheumatoid Arthritis: Comparison with Routinely Used Molecular Imaging Methods and Sensitivity to Chronic Nonsteroidal Antiinflammatory Drug Treatment

This study determined, using the intraarticular complete Freund adjuvant arthritis mice model, whether the radiotracer (99m)Tc-N-(triethylammonium)-3-propyl-[15]ane-N5 ((99m)Tc-NTP 15-5) targeting proteoglycans has a pathophysiologic validity for in vivo imaging of rheumatoid arthritis (RA) and its response to chronic nonsteroidal antiinflammatory drugs.

METHODS

We investigated the time course of cartilage remodeling by (99m)Tc-NTP 15-5 scintigraphy, bone damages by (99m)Tc-hydroxymethylene diphosphonate imaging, inflammation by (18)F-FDG PET, and joint proteoglycan content and pain behavior in animals, without and with meloxicam treatment. Paw circumference, thermal pain behavior, and histology as well as proteoglycan content of the whole joint were determined.

RESULTS

(99m)Tc-NTP 15-5 showed specific tracer accumulation within RA joints, with a significant increase in scintigraphic ratio observed in RA versus shams from day 3 to day 28. (18)F-FDG evidenced uptake in RA joints from day 15 to day 29. Animals treated with meloxicam (5 mg/kg) exhibited a dose-dependent decrease in both (99m)Tc-NTP 15-5 and (18)F-FDG uptake ratios versus saline-treated animals. (99m)Tc-hydroxymethylene diphosphonate bone scans were only positive at day 14 in RA versus shams, with a significant effect of meloxicam. An increase in proteoglycans of RA joint and thermal pain behavior were observed and were dose-dependently reduced by meloxicam.

CONCLUSION

These experimental results bring data in favor of the (99m)Tc-NTP 15-5 radiotracer for assessing, in vivo, cartilage remodeling in RA that could be used to monitor therapy.

Effect of methotrexate on collagen-induced arthritis assessed by micro-computed tomography and histopathological examination in female rats

We tested the hypothesis that micro-computed tomography (micro-CT) analysis provides a better quantitative readout of the therapeutic potential of methotrexate (MTX) for treating collagen-induced arthritis (CIA) in rats and compared to conventional histopathological examination. Rats were divided into three groups: Group 1 (G1) was treated with 0.9% saline, whereas groups 2 (G2) and 3 (G3) were boosted with type II collagen at days 0 and 7. Following the first collagen immunization, rats in G1 and G2 were treated with 0.9% saline and those in G3 were treated with 1.5 mg/kg MTX from day 14 to 28. All rats were sacrificed on day 28, at which point and all hind knee joints were analyzed by micro-CT and histopathological examination. Micro-CT analyses showed that bone volume and trabecular number were significantly decreased in G2 and G3 compared to G1 (p<0.01), as was percent bone volume (p<0.05 and p<0.01, respectively). However, bone surface/bone volume was significantly increased in G2 and G3 compared to G1 (p<0.05 and p<0.01, respectively). Trabecular separation was significantly increased in G3 compared to G1 (p<0.05). Histopathological examination showed that knee joints of rats in G2 and G3 showed severe joint destruction with inflammatory cell infiltration. However, cartilage destruction was slightly reduced in G3 compared to G2. Taken together, these results suggest that MTX treatment reduced cartilage destruction in rats with CIA, and micro-CT analyses made it possible to quantify arthritic bony lesion.

Micro-computed tomography evaluation and pathological analyses of female rats with collagen-induced arthritis

Imaging techniques have been introduced to assess the efficacy and toxicity of developing pharmaceuticals. The purpose of this study was to perform a comprehensive characterization of collagen-induced arthritis (CIA) in rats using micro-computed tomography (micro-CT) and to compare the results with data from conventional pathological examination. Arthritis was induced by collagen in 24 female Wistar rats. Micro-CT and pathological analyses were performed to assess arthritis progression. Micro-CT analysis showed marked joint destruction occurring in a time-dependent manner following collagen administration. Bone volume was significantly decreased in the tibia at weeks 3 and 4 compared to week 0 (p < 0.05 and p < 0.01, respectively). Additionally, percent bone volume was significantly reduced in the tibia at week 4 compared to week 0 (p < 0.05). In contrast, bone surface/bone volume and trabecular separation were significantly increased in the tibia of the animals at week 4 compared to week 0 (p < 0.05). Severe joint destruction with extensive inflammation, erosion of cartilage and bone, and infiltration of inflammatory cells were observed in the knee joints of the collagen-treated rats. Taken together, micro-CT made it possible to quantify CIA lesions and should be performed with pathological examination in rats.

Self-assembled glycol chitosan nanoparticles for disease-specific theranostics

Hydrophobically modified glycol chitosan (hGC) conjugates spontaneously form self-assembled nanoparticles (NPs) in aqueous conditions, and glycol chitosan NPs (CNPs) have been extensively studied for the past few decades. For disease-specific theranostics, CNPs could be simply modified with imaging agents, and the hydrophobic domains of hGC are available for encapsulation of various drugs. Based on the excellent physiochemical and biological properties, CNPs have been investigated for multimodal imaging and target specific drug delivery. In particular, a recent application of CNPs has shown great potential as an efficient theranostic system because the CNPs could be utilized for a disease-specific theranostic delivery system of different imaging agents and therapeutics, simultaneously. Furthermore, various therapeutic agents including chemo-drugs, nucleotides, peptides, and photodynamic chemicals could be simply encapsulated into the CNPs through hydrophobic or charge-charge interactions. Under in vivo conditions, the encapsulated imaging agents and therapeutic drugs have been successfully delivered to targeted diseases. In this article, the overall research progress on CNPs is reviewed from early works. The current challenges of CNPs to overcome in theranostics are also discussed, and continuous studies would provide more opportunities for early diagnosis of diseases and personalized medicine.

Prediction of antiarthritic drug efficacies by monitoring active matrix metalloproteinase-3 (MMP-3) levels in collagen-induced arthritic mice using the MMP-3 probe

Active matrix metalloproteinase-3 (MMP-3) is a prognostic marker of rheumatoid arthritis (RA). We recently developed an MMP-3 probe that can specifically detect the active form of MMP-3. The aim of this study was to investigate whether detection and monitoring of active MMP-3 could be useful to predict therapeutic drug responses in a collagen-induced arthritis (CIA) model. During the period of treatment with drugs such as methotrexate (MTX) or infliximab (IFX), MMP-3 mRNA and protein levels were correlated with fluorescence signals in arthritic joint tissues and in the serum of CIA mice. Also, bone volume density and erosion in the knee joints and the paws of CIA mice were measured with microcomputed tomography (micro-CT), X-ray, and histology to confirm drug responses. In joint tissues and serum of CIA mice, strong fluorescence signals induced by the action of active MMP-3 were significantly decreased when drugs were applied. The decrease in RA scores in drug-treated CIA mice led to fluorescence reductions, mainly as a result of down-regulation of MMP-3 mRNA or protein. The micro-CT, X-ray, and histology results clearly showed marked decreases in bone and cartilage destruction, which were consistent with the reduction of fluorescence by down-regulation of active MMP-3 in drug-treated CIA mice. We suggest that the MMP-3 diagnostic kit could be used to detect and monitor the active form of MMP-3 in CIA mice serum during a treatment course and thereby used to predict the drug response or resistance to RA therapies at an earlier stage. We hope that monitoring of active MMP-3 levels in arthritis patients using the MMP-3 diagnostic kit will be a promising tool for drug discovery, drug development, and monitoring of drug responses in RA therapy.

In vivo imaging of matrix metalloproteinase 12 and matrix metalloproteinase 13 activities in the mouse model of collagen-induced arthritis

OBJECTIVE

To develop enzyme-activatable Förster resonance energy transfer (FRET) substrate probes to detect matrix metalloproteinase 12 (MMP-12) and MMP-13 activities in vivo in mouse models of inflammatory arthritis.

METHODS

Peptidic FRET probes activated by MMP-12 and MMP-13 were reverse designed from inhibitors selected from a phosphinic peptide inhibitor library. Selectivity of the probes was demonstrated in vitro using MMP-1, MMP-2, MMP-3, MMP-12, and MMP-13. In vivo activation of the probes was tested in the zymosan-induced mouse model of inflammation, and probe specificity was evaluated by the MMP inhibitor GM6001 and specific synthetic inhibitors of MMP-12 and MMP-13. The probes were used to monitor these enzyme activities in the collagen-induced arthritis (CIA) model in vivo.

RESULTS

The MMP-12 and MMP-13 activity probes (MMP12ap and MMP13ap, respectively) discriminated between the activities of the 2 enzymes. The in vivo activation of these probes was inhibited by GM6001 and by their respective specific inhibitors. In the CIA model, MMP12ap activation peaked 5 days after disease onset and showed strong correlation with disease severity during this time (r = 0.85, P < 0.0001). MMP13ap activation increased gradually after disease onset and correlated with disease severity over a longer period of 15 days (r = 0.58, P < 0.0001).

CONCLUSION

We generated two selective FRET probes that can be used to monitor MMP-12 and MMP-13 activities in live animals. MMP12ap follows the initial stage of inflammation in CIA, while MMP13ap follows the progression of the disease. The specificity of these probes is useful in monitoring the efficacy of MMP inhibitors.

Molecular imaging of rheumatoid arthritis: emerging markers, tools, and techniques

Early diagnosis and effective monitoring of rheumatoid arthritis (RA) are important for a positive outcome. Instant treatment often results in faster reduction of inflammation and, as a consequence, less structural damage. Anatomical imaging techniques have been in use for a long time, facilitating diagnosis and monitoring of RA. However, mere imaging of anatomical structures provides little information on the processes preceding changes in synovial tissue, cartilage, and bone. Molecular imaging might facilitate more effective diagnosis and monitoring in addition to providing new information on the disease pathogenesis. A limiting factor in the development of new molecular imaging techniques is the availability of suitable probes. Here, we review which cells and molecules can be targeted in the RA joint and discuss the advances that have been made in imaging of arthritis with a focus on such molecular targets as folate receptor, F4/80, macrophage mannose receptor, E-selectin, intercellular adhesion molecule-1, phosphatidylserine, and matrix metalloproteinases. In addition, we discuss a new tool that is being introduced in the field, namely the use of nanobodies as tracers. Finally, we describe additional molecules displaying specific features in joint inflammation and propose these as potential new molecular imaging targets, more specifically receptor activator of nuclear factor κB and its ligand, chemokine receptors, vascular cell adhesion molecule-1, αVβ₃ integrin, P2X7 receptor, suppression of tumorigenicity 2, dendritic cell-specific transmembrane protein, and osteoclast-stimulatory transmembrane protein.

Inhibition of notch signalling ameliorates experimental inflammatory arthritis

OBJECTIVE

To test the hypothesis that Notch signalling plays a role in the pathogenesis of rheumatoid arthritis (RA) and to determine whether pharmacological inhibition of Notch signalling with γ-secretase inhibitors can ameliorate the RA disease process in an animal model.

METHODS

Collagen-induced arthritis was induced in C57BL/6 or Notch antisense transgenic mice by immunisation with chicken type II collagen (CII). C57BL/6 mice were administered with different doses of inhibitors of γ-secretase, an enzyme required for Notch activation, at disease onset or after onset of symptoms. Severity of arthritis was monitored by clinical and histological scores, and in vivo non-invasive near-infrared fluorescence (NIRF) images. Micro-CT was used to confirm joint destruction. The levels of CII antibodies and cytokines in serum were determined by ELISA and bead-based cytokine assay. The expression levels of cytokines were studied by quantitative PCR in rheumatoid synovial fibroblasts.

RESULTS

The data show that Notch signalling stimulates synoviocytes and accelerates their production of proinflammatory cytokines and immune responses involving the upregulation of IgG1 and IgG2a. Pharmacological inhibition of γ-secretase and antisense-mediated knockdown of Notch attenuates the severity of inflammatory arthritis, including arthritis indices, paw thickness, tissue damage and neutrophil infiltration, and reduces the levels of active NF-κB, ICAM-1, proinflammatory cytokines and matrix metalloproteinase-3 activity in the mouse model of RA.

CONCLUSIONS

These results suggest that Notch is involved in the pathogenesis of RA and that inhibition of Notch signalling is a novel approach for treating RA.

TNF-α gene silencing using polymerized siRNA/thiolated glycol chitosan nanoparticles for rheumatoid arthritis

Among various proinflammatory cytokines involved in the pathogenesis of rheumatoid arthritis (RA), tumor necrosis factor (TNF)-α plays a pivotal role in the release of other cytokines and induction of chronic inflammation. Even though siRNA has the therapeutic potential, they have a challenge to be delivered into the target cells because of their poor stability in physiological fluids. Herein, we design a nanocomplex of polymerized siRNA (poly-siRNA) targeting TNF-α with thiolated glycol chitosan (tGC) polymers for the treatment of RA. Poly-siRNA is prepared through self-polymerization of thiol groups at the 5' end of sense and antisense strand of siRNA and encapsulated into tGC polymers, resulting in poly-siRNA-tGC nanoparticles (psi-tGC-NPs) with an average diameter of 370 nm. In the macrophage culture system, psi-tGC-NPs exhibit rapid cellular uptake and excellent in vitro TNF-α gene silencing efficacy. Importantly, psi-tGC-NPs show the high accumulation at the arthritic joint sites in collagen-induced arthritis (CIA) mice. Treatment monitoring data obtained by the matrix metalloproteinase 3-specific nanoprobe and microcomputed tomography show that intravenous injection of psi-tGC-NPs significantly inhibits inflammation and bone erosion in CIA mice, comparable to methotrexate (5 mg/kg). Therefore, the availability of psi-tGC-NP therapy that target specific cytokines may herald new era in the treatment of RA.

Biomimetic aggrecan reduces cartilage extracellular matrix from degradation and lowers catabolic activity in ex vivo and in vivo models

Aggrecan, a major macromolecule in cartilage, protects the extracellular matrix (ECM) from degradation during the progression of osteoarthritis (OA). However, aggrecan itself is also susceptible to proteolytic cleavage. Here, the use of a biomimetic proteoglycan (mAGC) is presented, which functionally mimics aggrecan but lacks the known cleavage sites, protecting the molecule from proteolytic degradation. The objective of this study is to test the efficacy of this molecule in ex vivo (human OA synovial fluid) and in vivo (Sprague-Dawley rats) osteoarthritic models. These results indicate that mAGC's may protect articular cartilage against the loss of key ECM components, and lower catabolic protein and gene expression in both models. This suppression of matrix degradation has the potential to provide a healthy environment for tissue repair.

Molecular imaging: an innovative force in musculoskeletal radiology

OBJECTIVE

A review of the innovative role molecular imaging plays in musculoskeletal radiology is provided. Musculoskeletal molecular imaging is under development in four key areas: imaging the activity of osteoblasts and osteoclasts, imaging of molecular and cellular biomarkers of arthritic joint destruction, cellular imaging of osteomyelitis, and imaging generators of musculoskeletal pain.

CONCLUSION

Together, these applications suggest that next-generation musculoskeletal radiology will facilitate quantitative visualization of molecular and cellular biomarkers, an advancement that appeared futuristic just a decade ago.

Detection of active matrix metalloproteinase-3 in serum and fibroblast-like synoviocytes of collagen-induced arthritis mice

The activity of rheumatoid arthritis (RA) correlates with the expression of proteases. Among several proteases, matrix metalloproteinase-3 (MMP-3) is one of the biological markers used to diagnose RA. The active form of MMP-3 is a key enzyme involved in RA-associated destruction of cartilage and bone. Thus, detection of active MMP-3 in serum or in vivo is very important for early diagnosis of RA. In this study, a soluble MMP-3 probe was prepared to monitor RA progression by detecting expression of active MMP-3 in collagen-induced arthritis (CIA) mice in vivo in both serum and fibroblast-like synoviocytes (FLSs). The MMP-3 probe exhibited strong sensitivity to MMP-3 and moderate sensitivity to MMP-7 at nanomolecular concentrations, but was not sensitive to other MMPs such as MMP-2, MMP-9, and MMP-13. In an optical imaging study, the MMP-3 probe produced early and strong NIR fluorescence signals prior to observation of erythema and swelling in CIA mice. The MMP-3 probe was able to rapidly and selectively detect and monitor active MMP-3 in diluted serum from CIA mice. Furthermore, histological data demonstrated that activated FLSs in arthritic knee joints expressed active MMP-3. Together, our results demonstrated that the MMP-3 probe may be useful for detecting active MMP-3 for diagnosis of RA. More importantly, the MMP-3 probe was able to detect active MMP-3 in diluted serum with high sensitivity. Therefore, the MMP-3 probe developed in this study may be a very promising probe, useful as a biomarker for early detection and diagnosis of RA.

Photo-crosslinked hyaluronic acid nanoparticles with improved stability for in vivo tumor-targeted drug delivery

One of the major hurdles of the nanoparticles as drug carriers is the unintended burst release of loaded drugs during blood circulation. To surmount this issue, we developed photo-crosslinked hyaluronic acid nanoparticles (c-HANPs) with improved stability for tumor-targeted drug delivery. They were readily prepared via UV-triggered chemical crosslinking with the acrylate groups in the polymer backbone. The size of c-HANPs was not much different from that of uncrosslinked HANPs. However, c-HANPs exhibited significantly high stability in a physiological buffer and released the loaded drug, paclitaxel (PTX), in a sustained manner. It is noteworthy that the drug release rate from c-HANPs remarkably increased in the presence of hyaluronidase, an enzyme abundant at the intracellular compartments of the tumor cells. It was found from in vitro cellular uptake tests that c-HANPs were rapidly taken up by the tumor cells via the receptor (CD44)-mediated endocytosis, which was not inhibited by photo-crosslinking. In non-invasive animal imaging results, they showed higher tumor-targeting ability than uncrosslinked HANPs because high stability of c-HANPs enabled their long circulation in the body. Owing to the sustained release of the drug and enhanced tumor-targeting ability, c-HANPs showed higher therapeutic efficacy compared to free PTX and uncrosslinked HANPs. These data implied the promising potential of c-HANP as tumor-targeting drug carriers and demonstrated the remarkable effect of the improved stability upon the biodistribution and therapeutic efficacy of drug-loaded nanoparticles.

The activity against Ehrlich's ascites tumors of doxorubicin contained in self assembled, cell receptor targeted nanoparticle with simultaneous oral delivery of the green tea polyphenol epigallocatechin-3-gallate

Doxorubicin (DOX) is a well-known anticancer drug used for the treatment of a wide variety of cancers. However, undesired toxicity of DOX limits its uses. To address the issue of minimizing toxicity of DOX by making it targeted towards cancer cells, DOX was entrapped in self-assembled 6-O-(3-hexadecyloxy-2-hydroxypropyl)-hyaluronic acid (HDHA) nanoparticles. We hypothesized that by encapsulating the drug in biodegradable nanoparticles, its therapeutic efficacy would improve, if targeted against cancer cells. We synthesized cell receptor targeted, DOX loaded HDHA nanoparticles (NPs) and non-targeted DOX loaded O-hexadecylated dextran (HDD) nanoparticles (NPs) and characterized them for their entrapment efficiency, percent yield, drug load, surface morphology, particle size and in vitro drug release. The anticancer efficacy of DOX loaded HDHA-NPs was evaluated by measuring the changes in tumor volumes, tumor weights, and mean survival rate of Swiss albino mice grafted with Ehrlich's ascites carcinoma (EAC) cells. For this, the animals were given HDHA-DOX-NPs (1.5 mg/kg b.wt.) intravenously and a green tea polyphenol, Epigallocatechin-3-gallate (EGCG) (20 mg/kg b.wt.), orally through gavage. The targeted NP dose with EGCG significantly increased mean survival time of the animals and enhanced the therapeutic efficacy of the drug compared to the non-targeted NPs and free DOX. Further, we showed that these NPs (HDD and HDHA) were more active in the presence of EGCG than DOX alone in inducing apoptosis in EAC cells as evident by an increase in sub-G1 cells (percent), Annexin V positive cells and chromatin condensation along with the reduction in mitochondrial membrane potential (MMP). The study demonstrates that DOX loaded HDHA-NPs along with EGCG significantly inhibit the growth of EAC cells with ∼38-fold dose advantage compared to DOX alone and thus opens a new dimension in cancer chemotherapy.

Tumor-targeting multi-functional nanoparticles for theragnosis: new paradigm for cancer therapy

Theragnostic nanoparticles (NPs) contain diagnostic and therapeutic functions in one integrated system, enabling diagnosis, therapy, and monitoring of therapeutic response at the same time. For diagnostic function, theragnostic NPs require the inclusion of noninvasive imaging modalities. Among them, optical imaging has various advantages including sensitivity, real-time and convenient use, and non-ionization safety, which make it the leading technique for theragnostic NPs. For therapeutic function, theragnostic NPs have been applied to chemotherapy, photodynamic therapy, siRNA therapy and photothermal therapy. In this review, we present a recent progress reported in the development and applications of theragnostic NPs for cancer therapy. More specifically, we will focus on theragnostic NPs related with optical imaging, highlighting promising strategies based on optical imaging techniques.

Chemical biology for understanding matrix metalloproteinase function

The matrix metalloproteinase (MMP) family has long been associated with normal physiological processes such as embryonic implantation, tissue remodeling, organ development, and wound healing, as well as multiple aspects of cancer initiation and progression, osteoarthritis, inflammatory and vascular diseases, and neurodegenerative diseases. The development of chemically designed MMP probes has advanced our understanding of the roles of MMPs in disease in addition to shedding considerable light on the mechanisms of MMP action. The first generation of protease-activated agents has demonstrated proof of principle as well as providing impetus for in vivo applications. One common problem has been a lack of agent stability at nontargeted tissues and organs due to activation by multiple proteases. The present review considers how chemical biology has impacted the progress made in understanding the roles of MMPs in disease and the basic mechanisms of MMP action.