Tyrosine kinases as targets for the treatment of rheumatoid arthritis

Scanning Electron Microscopic Analysis of the Bone-Resorption Activity in Mature Osteoclasts

Bone homeostasis depends on the balance between bone deposition and bone resorption, which are mediated by the activity of osteoblasts and osteoclasts, respectively. Blocking osteoclast activity can be a therapeutic strategy in rheumatoid arthritis (RA) to reduce subsequent bone erosion. Therefore, investigating the activity of osteoclasts is essential for understanding the pathology of RA. Bone-resorption pits, which are caused by activated osteoclasts, are significantly increased in RA. Scanning electron microscopic analysis of bone-resorption pits is an effective method for understanding the pathology of RA. This chapter describes the method for observing the surface microstructure of pit formation on bone slices.

N-substituting perturbation on the interaction affinity and recognition specificity between rheumatic immune-related Abl SH3 domain and its peptoid ligands

Abl is a nonreceptor tyrosine kinase involved in a variety of disease pathways such as rheumatic immune. Full-length Abl protein consists of a catalytic tyrosine kinase (TK) domain as well as two regulatory Src homology domains 2 and 3 (SH2 and SH3, respectively); the latter recognizes and binds to those natural proline-rich peptide segments containing a PxxP motif on the protein surface of its interacting partners. However, natural peptides cannot bind effectively to the modular domain in high affinity and strong selectivity due to their small size and broad specificity. Here, a synthetic proline-rich peptide p41 was used as template; its structural diversity was extended by combinationally replacing the Pro0 and Pro+3 residues with a number of N-substituted amino acids. Consequently, peptide affinity change upon the replacement was derived to create a systematic N-substituting perturbation profile, from which we identified several N-substitution combinations at the Pro0 and Pro+3 residues of p41 PxxP motif that may moderately or significantly improve the peptide binding potency to Abl; they represent potent peptoid binders of Abl SH3 domain, with affinity improved considerably relative to p41. More significantly, the designed potent peptoids were also found to exhibit a good SH3-selectivity for their cognate Abl over other noncognate nonreceptor tyrosine kinases, with S = 9.7-fold.

Novel Bruton's tyrosine kinase inhibitor TAS5315 suppresses the progression of inflammation and joint destruction in rodent collagen-induced arthritis

Rheumatoid arthritis is an inflammatory autoimmune disease, characterized by autoantibody production, synovial inflammation, and joint destruction. Its pathogenesis is due to environmental factors and genetic backgrounds. Bruton's tyrosine kinase is a cytoplasmic non-receptor tyrosine kinase, expressed in most hematopoietic cell lineages, except T cells and plasma cells, and regulates various immune-related signaling pathways, thereby playing a crucial role in pathogenesis. Thus, inhibiting Bruton's tyrosine kinase may prove beneficial in treating autoimmune diseases. In the present study, we characterized Bruton's tyrosine kinase inhibitor, TAS5315, in vitro and evaluated its therapeutic effects in experimental arthritis models. TAS5315 markedly inhibited Bruton's tyrosine kinase enzyme activity and suppressed the B-cell receptor signaling pathway in Ramos cells. Moreover, it suppressed the expression of CD69, CD86, and MHC class II in mouse B lymphocytes and the production of TNF-α and MIP-1α in mouse macrophages and decreased bone resorption activity in mouse osteoclasts. Furthermore, it ameliorated the pathological changes in two rodent models of collagen-induced arthritis in vivo. TAS5315 improved bone mineral density and bone intensity. Thus, these results suggest that TAS5315 could be a promising therapeutic option for the treatment of rheumatoid arthritis.

NF-κB Signaling and Inflammation-Drug Repurposing to Treat Inflammatory Disorders?

NF-κB is a central mediator of inflammation, response to DNA damage and oxidative stress. As a result of its central role in so many important cellular processes, NF-κB dysregulation has been implicated in the pathology of important human diseases. NF-κB activation causes inappropriate inflammatory responses in diseases including rheumatoid arthritis (RA) and multiple sclerosis (MS). Thus, modulation of NF-κB signaling is being widely investigated as an approach to treat chronic inflammatory diseases, autoimmunity and cancer. The emergence of COVID-19 in late 2019, the subsequent pandemic and the huge clinical burden of patients with life-threatening SARS-CoV-2 pneumonia led to a massive scramble to repurpose existing medicines to treat lung inflammation in a wide range of healthcare systems. These efforts continue and have proven to be controversial. Drug repurposing strategies are a promising alternative to de novo drug development, as they minimize drug development timelines and reduce the risk of failure due to unexpected side effects. Different experimental approaches have been applied to identify existing medicines which inhibit NF-κB that could be repurposed as anti-inflammatory drugs.

Enhancing extracellular vesicles for therapeutic treatment of arthritic joints

Extracellular vesicles are small membrane-derived packages of information that are released from virtually all cell types. These nano-packages contain regulatory material including proteins, lipids, mRNA and microRNA and are a key mechanism of paracellular communication within a given microenvironment. Encompassed with a lipid bilayer, these organelles have been attributed numerous roles in regulating both physiological and pathological functions. Herein, we describe the role of EVs in the context of Rheumatoid and Osteoarthritis and explore how they could be harnessed to treat inflammatory and degenerative joint conditions. These structures offer a promising therapeutic strategy for treating musculoskeletal diseases due to their bioactive content, stability, small size and intrinsic ability to enter the avascular cartilage, a notoriously challenging tissue to target. We also discuss how EVs can be manipulated to load therapeutic cargo or present additional targeting moieties to enhance their beneficial actions and tissue regenerative properties.

Imatinib therapy for patients with recent-onset type 1 diabetes: a multicentre, randomised, double-blind, placebo-controlled, phase 2 trial

BACKGROUND

Type 1 diabetes results from autoimmune-mediated destruction of β cells. The tyrosine kinase inhibitor imatinib might affect relevant immunological and metabolic pathways, and preclinical studies show that it reverses and prevents diabetes. Our aim was to evaluate the safety and efficacy of imatinib in preserving β-cell function in patients with recent-onset type 1 diabetes.

METHODS

We did a multicentre, randomised, double-blind, placebo-controlled, phase 2 trial. Patients with recent-onset type 1 diabetes (<100 days from diagnosis), aged 18-45 years, positive for at least one type of diabetes-associated autoantibody, and with a peak stimulated C-peptide of greater than 0·2 nmol L^-1 on a mixed meal tolerance test (MMTT) were enrolled from nine medical centres in the USA (n=8) and Australia (n=1). Participants were randomly assigned (2:1) to receive either 400 mg imatinib mesylate (4 × 100 mg film-coated tablets per day) or matching placebo for 26 weeks via a computer-generated blocked randomisation scheme stratified by centre. Treatment assignments were masked for all participants and study personnel except pharmacists at each clinical site. The primary endpoint was the difference in the area under the curve (AUC) mean for C-peptide response in the first 2 h of an MMTT at 12 months in the imatinib group versus the placebo group, with use of an ANCOVA model adjusting for sex, baseline age, and baseline C-peptide, with further observation up to 24 months. The primary analysis was by intention to treat (ITT). Safety was assessed in all randomly assigned participants. This study is registered with ClinicalTrials.gov, NCT01781975 (completed).

FINDINGS

Patients were screened and enrolled between Feb 12, 2014, and May 19, 2016. 45 patients were assigned to receive imatinib and 22 to receive placebo. After withdrawals, 43 participants in the imatinib group and 21 in the placebo group were included in the primary ITT analysis at 12 months. The study met its primary endpoint: the adjusted mean difference in 2-h C-peptide AUC at 12 months for imatinib versus placebo treatment was 0·095 (90% CI -0·003 to 0·191; p=0·048, one-tailed test). This effect was not sustained out to 24 months. During the 24-month follow-up, 32 (71%) of 45 participants who received imatinib had a grade 2 severity or worse adverse event, compared with 13 (59%) of 22 participants who received placebo. The most common adverse events (grade 2 severity or worse) that differed between the groups were gastrointestinal issues (six [13%] participants in the imatinib group, primarily nausea, and none in the placebo group) and additional laboratory investigations (ten [22%] participants in the imatinib group and two [9%] in the placebo group). Per the trial protocol, 17 (38%) participants in the imatinib group required a temporary modification in drug dosing and six (13%) permanently discontinued imatinib due to adverse events; five (23%) participants in the placebo group had temporary modifications in dosing and none had a permanent discontinuation due to adverse events.

INTERPRETATION

A 26-week course of imatinib preserved β-cell function at 12 months in adults with recent-onset type 1 diabetes. Imatinib might offer a novel means to alter the course of type 1 diabetes. Future considerations are defining ideal dose and duration of therapy, safety and efficacy in children, combination use with a complimentary drug, and ability of imatinib to delay or prevent progression to diabetes in an at-risk population; however, careful monitoring for possible toxicities is required.

FUNDING

Juvenile Research Diabetes Foundation.

Soluble neuropilin-1 in gingival crevicular fluid is associated with rheumatoid arthritis: An exploratory case-control study

BACKGROUND

To explore the soluble Neuropilin-1 (sNRP-1) concentrations in gingival crevicular fluid (GCF) and the periodontal clinical status of patients with Rheumatoid Arthritis (RA).

MATERIALS AND METHODS

We conducted an exploratory study with 40 study participants, 20 with RA, and 20 healthy controls. Clinical and periodontal data were recorded, and GCF samples were obtained. sNRP-1 levels in GCF were determined by ELISA assay. Descriptive statistics, Mann-Whitney U test, Unpaired t-test, logistic regression model, and Area Under Receiver Operating Characteristic Curve (AUC-ROC) were made to explore the diagnostic performance accuracy.

RESULTS

RA patients had significantly higher levels of sNRP-1 in GCF (p ​= ​0.0447). The median levels of GCF-sNRP-1 were 208.85 ​pg/μl (IQR 131.03) in the RA group compared to 81.46 ​pg/μl (IQR 163.73) in the control group. We observed an association between the GCF-sNRP-1 concentrations and the RA diagnosis (OR:1.009; CI 1.00-1.001; p ​= ​0.047). The diagnosis of chronic periodontitis was also associated with RA (OR: 6.9; CI 1.52-31.37; p ​= ​0.012). Moreover, the AUC-ROC of GCF-sNRP-1 concentrations combined with periodontal clinical parameters such as periodontal probing depth and periodontal inflamed surface area was 0.80.

CONCLUSION

This exploratory case-control study shows that RA patients had significantly higher levels of sNRP-1 in GCF. New longitudinal studies are necessary to evaluate the role of NRP-1 in periodontal tissues and consider it an oral biomarker with clinical value in RA.

Minor immunosuppressive spiroorthoester group-containing pregnane glycosides from the root barks of Periploca sepium

LC-MS guided chemical investigation of the periploside-rich extract of the root barks of Periploca sepium afforded six new minor pregnane glycosides, named periplosides A1-A6 (1-6). Their structures were characterized on the basis of extensive spectroscopic analysis. Compounds 1-6 were evaluated for their inhibitory activities against the proliferation of T and B lymphocytes in vitro, among them, compound 5 exhibited significant inhibitory activities and the most favorite selective index (SI) values against the proliferation of T lymphocyte (IC₅₀ = 0.30 μM, SI = 176) and B lymphocyte (IC₅₀ = 0.55 μM, SI = 97).

Targeted delivery in scleroderma fibrosis

Systemic sclerosis (SSc) is considered one of the most challenging and difficult to treat among rheumatic disorders, due to its severity, multiorgan manifestation and different outcomes. It manifests fibrosis in different organs, mostly in skin and lungs. The skin fibrosis expression is considered the first sign of the disease and usually it is followed by internal organ fibrosis. An aberrant immune system activation seems to relate to the expression of the disease, but even environmental influences and dysregulation of many molecules signalling pathways are involved in the development of the disease. Current therapies are limited and characterized by multiple side effects: systemic route is the elective administration route, which decreases patient adherence to the therapy, as they are often already bothered by pain and disfigurement. Treatments available are organ-based, originally indicated for other conditions and there is no therapy available to reduce the fibroblast population size within existing fibrotic lesions. Disease-modifying therapies or immunomodulatory agents that are highly effective in other rheumatic diseases have shown disappointing results in SSc. There are thus no standardized and effective treatments for this disease, and there are even unanswered questions related to the insurgence of the pathology and all the mechanisms involved. An ideal approach could be considered "targeted therapy" that will be an increasingly attainable objective insofar as our understanding of the disease improves. The advantages in identifying the molecule and the signalling pathways involved in the pathology have helped to find some novel compounds for the therapy of scleroderma fibrosis or following innovative uses for already-approved drugs, corroborated by many clinical studies.

1H-NMR-Based Analysis for Exploring Knee Synovial Fluid Metabolite Changes after Local Cryotherapy in Knee Arthritis Patients

Rehabilitation using cryotherapy has widely been used in inflammatory diseases to relieve pain and decrease the disease activity. The aim of this study was to explore the metabolite changes in inflammatory knee-joint synovial fluids following local cryotherapy treatment (ice or cold CO2). We used proton nuclear magnetic resonance (1H NMR) spectroscopy to assess the metabolite patterns in synovial fluid (SF) in patients with knee arthritis (n = 46) before (D0) and after (D1, 24 h later) two applications of local cryotherapy. Spectra from aqueous samples and organic extracts were obtained with an 11.75 Tesla spectrometer. The metabolite concentrations within the SF were compared between D1 and D0 using multiple comparisons with the application of a false discovery rate (FDR) adjusted at 10% for each metabolite. A total of 32 metabolites/chemical structures were identified including amino acids, organic acids, fatty acids or sugars. Pyruvate, alanine, citrate, threonine was significantly higher at D1 vs D0 (p < 0.05). Tyrosine concentration significantly decreases after cryotherapy application (p < 0.001). We did not observe any effect of gender and cooling technique on metabolite concentrations between D0 and D1 (p > 0.05). The present study provides new insight into a short-term effect of cold stimulus in synovial fluid from patients with knee arthritis. Our observations suggest that the increased level of metabolites involved in energy metabolism may explain the underlying molecular pathways that mediate the antioxidant and anti-inflammatory capacities of cryotherapy.

A network pharmacology approach to explore the potential targets underlying the effect of sinomenine on rheumatoid arthritis

OBJECTIVE

To explore the potential targets underlying the effect of sinomenine (SIN) on rheumatoid arthritis (RA) by utilizing a network pharmacology approach.

METHODS

SIN and its drug targets were identified using network analysis followed by experimental validation. First, the Pharmmapper, UniProt and GeneCards databases were mined for information relevant to the prediction of SIN targets and RA-related targets. Second, the SIN-target gene and SIN-RA target gene networks were created in Cytoscape software followed by the collection of the candidate targets of each component by R software. Eventually, the key targets and enriched pathways were examined by Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis.

RESULTS

Sixty-seven potential targets of SIN and 3797 related targets involved in RA were subjected to network analysis, and the 20 intersection targets indicated the principal pathways linked to RA. Additionally, 16 key targets, which were linked to more than three genes, were determined to be crucial genes. GO analysis showed that 14 biological processes, 5 cellular components and 2 molecular functions were identified, when corrected by a P value ≤ 0.01. Seven related signaling pathways were identified by KEGG analysis, when corrected according to a Bonferroni P value ≤ 0.05.

CONCLUSION

The present study explored the potential targets and signaling pathways of SIN during the treatment of RA, which may help to illustrate the mechanism (s) involved in the action of SIN and may provide a better understanding of its anti-rheumatoid arthritis effects in terms of inhibiting angiogenesis, synovial hyperplasia, and bone destruction.

Tyrosine kinase inhibitors for the treatment of rheumatoid arthritis: phase I to Ⅱ clinical trials

Introduction: Rheumatoid arthritis (RA) is a chronic, refractory disorder caused by autoimmunity in the synovial joints. Disease-modifying anti-rheumatic drugs (DMARDs) and biologicals offer remission in only two-thirds of RA patients within 3 months, hence new therapeutic approaches are necessary. Tyrosine kinase inhibitors (TKIs) are newly developed small molecule drugs which have demonstrated encouraging results in this disease.Areas covered: The key findings from phase I and II clinical trials that have investigated the use of novel TKIs in the treatment of RA are discussed. We examined the literature published between January 2014 to January 2019 using electronic databases including PubMed, Web of Science, Medline, Embase, and Google Scholar. Additional information about phase I and II trials on the ClinicalTrial.gov website up to January 2019 was also retrieved.Expert opinion: JAK inhibitors are promising drugs with sound efficacy and acceptable safety and may be beneficial to patients who do not respond to DMARDs and biologicals. The response rates among RA patients to TKIs are diverse; genetic and environmental factors may be involved in the varying responses which are closely related to the pathogenesis of RA. Future studies may reveal the underlying mechanisms of resistance and non-response.

Multi-tissue network analysis for drug prioritization in knee osteoarthritis

Knee osteoarthritis (OA) is a joint disease that affects several tissues: cartilage, synovium, meniscus and subchondral bone. The pathophysiology of this complex disease is still not completely understood and existing pharmaceutical strategies are limited to pain relief treatments. Therefore, a computational method was developed considering the diverse mechanisms and the multi-tissue nature of OA in order to suggest pharmaceutical compounds. Specifically, weighted gene co-expression network analysis (WGCNA) was utilized to identify gene modules that were preserved across four joint tissues. The driver genes of these modules were selected as an input for a network-based drug discovery approach. WGCNA identified two preserved modules that described functions related to extracellular matrix physiology and immune system responses. Compounds that affected various anti-inflammatory pathways and drugs targeted at coagulation pathways were suggested. 9 out of the top 10 compounds had a proven association with OA and significantly outperformed randomized approaches not including WGCNA. The method presented herein is a viable strategy to identify overlapping molecular mechanisms in multi-tissue diseases such as OA and employ this information for drug discovery and compound prioritization.

Non-receptor tyrosine kinase signaling in autoimmunity and therapeutic implications

Autoimmune diseases are characterized by impaired immune tolerance towards self-antigens, leading to enhanced immunity to self by dysfunctional B cells and/or T cells. The activation of these cells is controlled by non-receptor tyrosine kinases (NRTKs), which are critical mediators of antigen receptor and cytokine receptor signaling pathways. NRTKs transduce, amplify and sustain activating signals that contribute to autoimmunity, and are counter-regulated by protein tyrosine phosphatases (PTPs). The function of and interaction between NRTKs and PTPs during the development of autoimmunity could be key points of therapeutic interference against autoimmune diseases. In this review, we summarize the current state of knowledge of the functions of NRTKs and PTPs involved in B cell receptor (BCR), T cell receptor (TCR), and cytokine receptor signaling pathways that contribute to autoimmunity, and discuss their targeting for therapeutic approaches against autoimmune diseases.

SYK Inhibition Potentiates the Effect of Chemotherapeutic Drugs on Neuroblastoma Cells in Vitro

Neuroblastoma is a malignancy arising from the developing sympathetic nervous system and the most common and deadly cancer of infancy. New therapies are needed to improve the prognosis for high-risk patients and to reduce toxicity and late effects. Spleen tyrosine kinase (SYK) has previously been identified as a promising drug target in various inflammatory diseases and cancers but has so far not been extensively studied as a potential therapeutic target in neuroblastoma. In this study, we observed elevated SYK gene expression in neuroblastoma compared to neural crest and benign neurofibroma. While SYK protein was detected in the majority of examined neuroblastoma tissues it was less frequently observed in neuroblastoma cell lines. Depletion of SYK by siRNA and the use of small molecule SYK inhibitors significantly reduced the cell viability of neuroblastoma cell lines expressing SYK protein. Moreover, SYK inhibition decreased ERK1/2 and Akt phosphorylation. The SYK inhibitor BAY 61-3606 enhanced the effect of different chemotherapeutic drugs. Transient expression of a constitutive active SYK variant increased the viability of neuroblastoma cells independent of endogenous SYK levels. Collectively, our findings suggest that targeting SYK in combination with conventional chemotherapy should be further evaluated as a treatment option in neuroblastoma.

Treatment Effects of the Second-Generation Tyrosine Kinase Inhibitor Dasatinib on Autoimmune Arthritis

Rheumatoid arthritis (RA) is a multifactorial autoimmune disease that primarily manifests as persistent synovitis and progressive joint destruction. Imatinib exhibited a therapeutic effect in murine collagen-induced arthritis (CIA) via selective inhibition tyrosine kinases. The second-generation tyrosine kinase inhibitor dasatinib exhibits more durable hematological and cytogenetic effects and more potency compared to imatinib. However, the effect of dasatinib on CIA is poorly understood. The present study investigated the treatment effect of dasatinib on autoimmune arthritis. We demonstrated that dasatinib alleviated arthritis symptoms and histopathological destruction in CIA mice. Dasatinib treatment inhibited the production of proinflammatory cytokines including IL-1β, TNF-α, and IL-6, and promoted the production of the anti-inflammatory cytokine IL-10. Dasatinib treatment also suppressed the expression of anti-mouse CII antibodies including total IgG, IgG1, IgG2, and IgG2b, in CIA mice. We further demonstrated that dasatinib inhibited the migration and proliferation of fibroblast-like synoviocytes (FLS) from RA patients and promoted FLS apoptosis. The mRNA expression of MMP13, VEGF, FGF, and DKK1 was down-regulated in FLS treated with dasatinib. Our findings suggest that dasatinib exhibited treatment effects on CIA mice and that FLS are an important target cell of dasatinib treatment in autoimmune arthritis.

Notch Signaling Activity Determines Uptake and Biological Effect of Imatinib in Systemic Sclerosis Dermal Fibroblasts

Tyrosine kinase inhibitors have emerged as a therapeutic option for rheumatic diseases such as systemic sclerosis (SSc). Because tyrosine kinases like c-Abl kinase are important for fibroblast activation and fibrosis development in SSc, the c-Abl inhibitor imatinib was proposed for SSc treatment. Transporters for organic cations have become increasingly recognized as an important determinant for uptake and efficacy of tyrosine kinase inhibitors. Therefore, we investigated the role of organic cation transporters in the uptake of imatinib. Moreover, the influence of important SSc pathogenetic factors, like PDGF and Notch pathway activation on these uptake processes, has been studied. We showed that organic cation transporters OCT1-3, novel organic cation transporters OCTN1/2, and the multidrug and toxin extrusion protein MATE1 are expressed in healthy dermal and SSc fibroblasts. Decreased expression levels of MATE1 and decreased imatinib uptake were measured in SSc fibroblasts. In small interfering RNA experiments, MATE1 was identified as key transporter for imatinib uptake and biological effect in dermal fibroblasts. Furthermore, PDGF reduced imatinib uptake by decreasing MATE1 expression in SSc fibroblasts, but not in healthy fibroblasts. Blocking the Notch pathway in SSc fibroblasts increased MATE1 transporter expression and imatinib uptake. In conclusion, MATE1-mediated transport governs therapeutic efficacy of imatinib in SSc.

A cytokine protein-protein interaction network for identifying key molecules in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory disease of the synovial joints. Though the current RA therapeutics such as disease-modifying antirheumatic drugs (DMARDs), nonsteroidal anti-inflammatory drugs (NSAIDs) and biologics can halt the progression of the disease, none of these would either dramatically reduce or cure RA. So, the identification of potential therapeutic targets and new therapies for RA are active areas of research. Several studies have discovered the involvement of cytokines in the pathogenesis of this disease. These cytokines induce signal transduction pathways in RA synovial fibroblasts (RASF). These pathways share many signal transducers and their interacting proteins, resulting in the formation of a signaling network. In order to understand the involvement of this network in RA pathogenesis, it is essential to identify the key transducers and their interacting proteins that are part of this network. In this study, based on a detailed literature survey, we have identified a list of 12 cytokines that induce signal transduction pathways in RASF. For these cytokines, we have built a signaling network using the protein-protein interaction (PPI) data that was obtained from public repositories such as HPRD, BioGRID, MINT, IntAct and STRING. By combining the network centrality measures with the gene expression data from the RA related microarrays that are available in the open source Gene Expression Omnibus (GEO) database, we have identified 24 key proteins of this signaling network. Two of these 24 are already drug targets for RA, and of the remaining, 12 have direct PPI links to some of the current drug targets of RA. Therefore, these key proteins seem to be crucial in the pathogenesis of RA and hence might be treated as potential drug targets.

Discovery of a highly selective JAK3 inhibitor for the treatment of rheumatoid arthritis

Janus tyrosine kinase 3 (JAK3) is expressed in lymphoid cells and is involved in the signalling of T cell functions. The development of a selective JAK3 inhibitor has been shown to have a potential benefit in the treatment of autoimmune disorders. In this article, we developed the 4-aminopiperidine-based compound RB1, which was highly selective for JAK3 inhibition, with an IC₅₀ of value of 40 nM, but did not inhibit JAK1, JAK2 or tyrosine kinase 2 (TYK2) at concentrations up to 5 µM. Furthermore, RB1 also exhibited favourable selectivity against a panel of representative kinases. In a battery of cytokine-stimulated cell-based assays, this potent inhibitor of JAK3 activity with good selectivity against other kinases could potently inhibit JAK3 activity over the activity of JAK1 or JAK2 (over at least 100-fold). A combination of liquid chromatography-mass spectrometry (LC-MS) experiments validated that RB1 covalently modified the unique cysteine 909 residue in JAK3. In vivo, RB1 exerted significantly improved pathology in the joints of a collagen-induced arthritis mouse model. The reasonable pharmacokinetics properties (F = 72.52%, T1/2 = 14.6 h) and favourable results of toxicology experiments (LD₅₀ > 2 g/kg) suggest that RB1 has the potential to be an efficacious treatment for RA.

Rheumatoid Arthritis: A Novel Approach in Diagnosis and Treatment

The rheumatoid arthritis is chronic disease with progressive course and deteriorations of joints as well as other organs. The pathogenesis of rheumatoid arthritis is characterized with chronic synovitis and inflammation. The main roles in development of rheumatoid arthritis have auto-reactive T cells and inflammatory cytokines, especially tumor necrosis factor α, interleukin 1 and interleukin 6. The management of rheumatoid arthritis has evolved significantly in the past twenty years, especially with introduction new diagnostic criteria by European League for Rheumatoid Arthritis which are very sensitive for early arthritis. The main goal of treating rheumatoid arthritis is to start with therapy in the phase of the disease when destruction of joints can still be prevented. Therapeutic strategies for rheumatoid arthritis involve wide palette of different drugs which can be divided into conventional and biological Disease Modifying Anthirheumatic Drugs. The use of methotrexate in combination with biological drugs provide targeting not only structural changes in rheumatoid arthritis but also and immunological pathways in development of rheumatoid arthritis. These drugs synergistically provide clinical remission and low activity of rheumatoid arthritis in the majority of patients. The uses of biological drugs are limited due their high costs or safety profile. In order to reduce costs and toxicity in the treatment of rheumatoid arthritis, new treat- to –target concept is established. The new class of drugs which modulate signal pathways and activity of tyrosine kinase are under investigations in post marketing surveys in patients with rheumatoid arthritis as in efficacy as in safety issues.

Bone Resorption Activity in Mature Osteoclasts

Bone homeostasis depends on balanced bone deposition and bone resorption, which are mediated by osteoblasts and osteoclasts, respectively. As one therapeutic strategy, the blockage of osteoclast activity reduces subsequent bone erosion. Morphological analysis of bone resorption pits formed by osteoclasts by using scanning electron microscope is an effective method for understanding rheumatoid arthritis. Here we describe methods for observing surface microstructure of pits formed by osteoclasts on hard tissue sections.

Novel LCK/FMS inhibitors based on phenoxypyrimidine scaffold as potential treatment for inflammatory disorders

Tyrosine kinases including LCK and FMS are involved in inflammatory disorders as well as many types of cancer. Our team has designed and synthesized thirty novel pyrimidine based inhibitors targeting LCK, classified into four different series (amides, ureas, imines (Schiff base) and benzylamines). Twelve of them showed nanomolar IC₅₀ values. Compound 7g showed excellent selectivity profile and was selectively potent over FMS kinase (IC₅₀ value of 4.6 nM). Molecular docking study was performed to help us rationalize the obtained results and predict the possible binding mode for our compounds in both LCK and FMS. Based on the obtained biological assay data and modelling results, a detailed SAR study was discussed. As a further testing regarding the anti-inflammatory effect of the new compounds, in vitro cellular assay over RAW 264.7 macrophages was performed. Compound 7g exhibited excellent anti-inflammatory effect. Therefore, we report the design of novel phenoxypyrimidine derivatives as potent and selective LCK inhibitors and the discovery of 7g as potent and selective FMS/LCK dual inhibitor for the potential application in inflammatory disorders including rheumatoid arthritis (RA).

Compensatory anabolic signaling in the sarcopenia of experimental chronic arthritis

Inflammatory activity in rheumatoid arthritis may alter the regulation of muscle mass leading to a secondary sarcopenia, commonly termed rheumatoid cachexia (RC). We characterized alterations to muscle structure and various pro-inflammatory, catabolic and regenerative markers in an animal model of RC. Antigen induced arthritis (AiA) was performed in 20 male adult rabbits. AiA animals exhibited significantly less weight gain, a markedly elevated serum C-reactive protein (CRP), lighter muscles with shorter cross-sectional diameter and increased myonuclei when compared to controls. Atrogin-1 and MuRF-1 were up-regulated alongside an increase in IL-1β, active NF-κB and a higher ratio of phosphorylated to inactive p38 MAPK. CCL-2 and TNF levels were reduced and IL-6 was unchanged between groups. We observed decreased pSTAT3, unchanged pSTAT1 and Myf5, but increased Pax7, MyoD and myogenin. AiA rabbits had a reduction in myostatin from gastrocnemii and synovium with a congruent decrease in serum myostatin compared to controls. Chronic arthritis induced an RC-like secondary sarcopenia with increased muscle protein breakdown. Elevated IL-1β may trigger proteolysis via elevated NF-κB and p38 MAPK signaling with a compensatory anabolic response suggested by myonuclear expansion, increased Pax7, MyoD and myogenin, reduced pSTAT3 as well as reduced serum, synovial and muscular myostatin.

Importance of the novel organic cation transporter 1 for tyrosine kinase inhibition by saracatinib in rheumatoid arthritis synovial fibroblasts

Recent therapeutic approaches of rheumatoid arthritis (RA) address the use of small molecules such as tyrosine kinase inhibitors (TKIs). However, the TKIs developed to date have important side effects and/or scarce efficacy in inflammatory diseases such as RA. Since intracellular effective TKIs must enter the cell to reach their intracellular targets, here we investigated the interaction of the TKI saracatinib, a dual inhibitor of c-Src and c-Abl signaling, with transporters for organic cations as well as the role of these transporters for the biological effect of saracatinib in human RA-synovial fibroblasts (hRASF). Saracatinib significantly reduced proliferation of hRASF. The cellular saracatinib uptake was mainly dependent on the human novel organic cation transporter 1 (hOCTN1), which showed the highest apparent affinity for saracatinib among all other transporters for organic cations analyzed here. In hRASF, saracatinib biologic function was dependent on hOCTN1. Further analysis showed that disease specific factors (pH, inflammatory cytokines such as TNFα) regulated saracatinib uptake in hRASF. The knowledge of which transporters mediate the specific uptake of TKIs in target cells and of how the expression and function of such transporters are regulated in RA is of highest priority to develop effective drugs for successful therapy with minimal side-effects.

Irreversible inhibition of BTK kinase by a novel highly selective inhibitor CHMFL-BTK-11 suppresses inflammatory response in rheumatoid arthritis model

BTK plays a critical role in the B cell receptor mediated inflammatory signaling in the rheumatoid arthritis (RA). Through a rational design approach we discovered a highly selective and potent BTK kinase inhibitor (CHMFL-BTK-11) which exerted its inhibitory efficacy through a covalent bond with BTK Cys481. CHMFL-BTK-11 potently blocked the anti-IgM stimulated BCR signaling in the Ramos cell lines and isolated human primary B cells. It significantly inhibited the LPS stimulated TNF-α production in the human PBMC cells but only weakly affecting the normal PBMC cell proliferation. In the adjuvant-induced arthritis rat model, CHMFL-BTK-11 ameliorated the inflammatory response through blockage of proliferation of activated B cells, inhibition of the secretion of the inflammatory factors such as IgG1, IgG2, IgM, IL-6 and PMΦ phagocytosis, stimulation of secretion of IL-10. The high specificity of CHMFL-BTK-11 makes it a useful pharmacological tool to further detect BTK mediated signaling in the pathology of RA.

Discoidin domain receptor 2 mediates collagen-induced activation of membrane-type 1 matrix metalloproteinase in human fibroblasts

Membrane-type 1 matrix metalloproteinase (MT1-MMP) is a membrane-bound MMP that is highly expressed in cells with invading capacity, including fibroblasts and invasive cancer cells. However, pathways of MT1-MMP up-regulation are not clearly understood. A potential physiological stimulus for MT1-MMP expression is fibrillar collagen, and it has been shown that it up-regulates both MT1-MMP gene and functions in various cell types. However, the mechanisms of collagen-mediated MT1-MMP activation and its physiological relevance are not known. In this study, we identified discoidin domain receptor 2 (DDR2) as a crucial receptor that mediates this process in human fibroblasts. Knocking down DDR2, but not the β1 integrin subunit, a common subunit for all collagen-binding integrins, inhibited the collagen-induced MT1-MMP-dependent activation of pro-MMP-2 and up-regulation of MT1-MMP at the gene and protein levels. Interestingly, DDR2 knockdown or pharmacological inhibition of DDR2 also inhibited the MT1-MMP-dependent cellular degradation of collagen film, suggesting that cell-surface collagen degradation by MT1-MMP involves DDR2-mediated collagen signaling. This DDR2-mediated mechanism is only present in non-transformed mesenchymal cells as collagen-induced MT1-MMP activation in HT1080 fibrosarcoma cells and MT1-MMP function in MDA-MB231 breast cancer cells were not affected by DDR kinase inhibition. DDR2 activation was found to be noticeably more effective when cells were stimulated by collagen without the non-helical telopeptide region compared with intact collagen fibrils. Furthermore, DDR2-dependent MT1-MMP activation by cartilage was found to be more efficient when the tissue was partially damaged. These data suggest that DDR2 is a microenvironment sensor that regulates fibroblast migration in a collagen-rich environment.

Identification of functional pathways associated with the conditional ablation of serum response factor in Dstncorn1 mice

The aim of the present study was to investigate the signaling pathways associated with functional alterations in corneal tissues following the conditional ablation of serum response factor (Srf) in Dstn^corn1 mice. The gene expression profiling array GSE49688, which includes 3 samples each from the wild-type (WT), Dstn^corn1 mutant (corn1) and corn1 mice following the conditional ablation of Srf from the corneal epithelium [namely rescued (res)] mouse groups, was downloaded from the Gene Expression Omnibus database. The limma package was used to identify differentially expressed genes (DEGs) among the three mouse groups. DEGs were subsequently analyzed by dynamic comparison, hierarchical clustering and pathway enrichment analysis. Pathway alteration scores were also calculated in order to study the dynamic metergasis of each identified pathway. A total of 788 DEGs were identified between the corn1 and res groups, 1,365 DEGs were identified between the corn1 and WT groups, and 852 DEGs were identified between the res and WT groups. Among these DEGs, 228 genes were differentially expressed across all three groups, and were mainly enriched in signaling pathways involved in the regulation of the actin cytoskeleton, including the cofilin 1 (CFL1), the mitogen-activated protein kinase (MAPK) signaling pathway and focal adhesion. The dilated cardiomyopathy signaling pathway displayed the highest alteration score, and was enriched with integrin and integrin β-6 (ITGB6). In conclusion, the actin cytoskeleton regulatory pathway, MAPK and dilated cardiomyopathy signaling pathways, as well as CFL1 and ITGB6 genes, may be regulated by Srf to serve important roles in the progression of corneal disease.

Janus kinase inhibitors for rheumatoid arthritis

Treatment of autoimmune diseases, such as rheumatoid arthritis (RA), has advanced substantially over the past decade with the development of biologics targeting inflammatory cytokines. Recent progress in treating RA has been achieved with janus kinase (JAK) inhibitors (Jakinibs), an orally available disease-modifying anti-rheumatic drug targeting the intracellular kinase JAK and with similar efficacy to biologics. The first Jakinib approved for RA was tofacitinib, which exerted superiority to methotrexate and non-inferiority to tumor necrosis factor (TNF) inhibitors. In recent years, the Jakinib baricitinib has demonstrated superiority to both methotrexate and a TNF inhibitor, adalimumab. Given these promising findings, Jakinibs are expected to represent the next generation compounds for treating RA, and a number of Jakinibs are currently in clinical trials. Jakinibs can differ substantially in their selectivity against JAKs; tofacitinib and baricitinib target multiple JAKs, whereas the most recently developed Jakinibs target only a single JAK. The influence of Jakinib selectivity on efficacy and side effects is of great interest, requiring further careful observation.

Current concepts in the management of rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by inflammation and joint destruction that causes significant morbidity and mortality. However, the combined use of methotrexate, a synthetic disease-modifying antirheumatic drug (DMARD), and biologic DMARD has revolutionized treatment of RA. Clinical remission is now realistic targets, achieved by a large proportion of RA patients, and rapid and appropriate induction of remission by intensive treatment with biological DMARD and methotrexate is prerequisite to halt joint damage and functional disabilities. However, biological DMARD is limited to intravenous or subcutaneous uses and orally available small but strong molecules have been developed. Oral administration of tofacitinib targeting the Janus kinase (JAK) is significantly effective than placebo in active patients with methotrexatenaïve, inadequately responsive to methotrexate or tumor necrosis factor (TNF)-inhibitors. The efficacy was rapid and as strong as adalimumab, a TNF-inhibitor. Meanwhile, association of tofacitinib on carcinogenicity and malignancy is under debate and further investigation on post-marketing survey would be warranted. On the other hand, discontinuation of a biological DMARD without disease flare is our next goal and desirable from the standpoint of risk reduction and cost effectiveness, especially for patients with clinical remission. Recent reports indicate that more than half of early RA patients could discontinue TNF-targeted biological DMARD without clinical flare and functional impairment after obtaining clinical remission. Contrarily, for established RA, fewer patients sustained remission after the discontinuation of biological DMARD and "deep remission" at the discontinuation was a key factor to keep the treatment holiday of biological DMARD.

Ability of Interleukin-33- and Immune Complex-Triggered Activation of Human Mast Cells to Down-Regulate Monocyte-Mediated Immune Responses

OBJECTIVE

Mast cells have been implicated in the pathogenesis of rheumatoid arthritis (RA). In particular, their activation by interleukin-33 (IL-33) has been linked to the development of arthritis in animal models. The aim of this study was to evaluate the functional responses of human mast cells to IL-33 in the context of RA.

METHODS

Human mast cells were stimulated with IL-33 combined with plate-bound IgG or IgG anti-citrullinated protein antibodies (ACPAs), and their effects on monocyte activation were evaluated. Cellular interactions of mast cells in RA synovium were assessed by immunofluorescence analysis, and the expression of messenger RNA (mRNA) for mast cell-specific genes was evaluated in synovial biopsy tissue from patients with early RA who were naive to treatment with disease-modifying antirheumatic drugs.

RESULTS

IL-33 induced the up-regulation of Fcγ receptor type IIa and enhanced the activation of mast cells by IgG, including IgG ACPAs, as indicated by the production of CXCL8/IL-8. Intriguingly, mast cell activation triggered with IL-33 and IgG led to the release of mediators such as histamine and IL-10, which inhibited monocyte activation. Synovial mast cells were found in contact with CD14+ monocyte/macrophages. Finally, mRNA levels of mast cell-specific genes were inversely associated with disease severity, and IL-33 mRNA levels showed an inverse correlation with the levels of proinflammatory markers.

CONCLUSION

When human mast cells are activated by IL-33, an immunomodulatory phenotype develops, with human mast cells gaining the ability to suppress monocyte activation via the release of IL-10 and histamine. These findings, together with the presence of synovial mast cell-monocyte interactions and the inverse association between the expression of mast cell genes at the synovial level and disease activity, suggest that these newly described mast cell-mediated inhibitory pathways might have a functional relevance in the pathogenesis of RA.

From desk to bed: computational simulations provide indication for rheumatoid arthritis clinical trials

Background

Rheumatoid arthritis (RA) is among the most common human systemic autoimmune diseases, affecting approximately 1% of the population worldwide. To date, there is no cure for the disease and current treatments show undesirable side effects. As the disease affects a growing number of individuals, and during their working age, the gathering of all information able to improve therapies -by understanding their and the disease mechanisms of action- represents an important area of research, benefiting not only patients but also societies. In this direction, network analysis methods have been used in previous work to further our understanding of this complex disease, leading to the identification of CRKL as a potential drug target for treatment of RA. Here, we use computational methods to expand on this work, testing the hypothesis in silico.

Results

Analysis of the CRKL network -available at http://www.picb.ac.cn/ClinicalGenomicNTW/software.html- allows for investigation of the potential effect of perturbing genes of interest. Within the group of genes that are significantly affected by simulated perturbation of CRKL, we are lead to further investigate the importance of PXN. Our results allow us to (1) refine the hypothesis on CRKL as a novel drug target (2) indicate potential causes of side effects in on-going trials and (3) importantly, provide recommendations with impact on on-going clinical studies.

Conclusions

Based on a virtual network that collects and connects a large number of the molecules known to be involved in a disease, one can simulate the effects of controlling molecules, allowing for the observation of how this affects the rest of the network. This is important to mimic the effect of a drug, but also to be aware of -and possibly control- its side effects. Using this approach in RA research we have been able to contribute to the field by suggesting molecules to be targeted in new therapies and more importantly, to warrant efficacy, to hypothesise novel recommendations on existing drugs currently under test.

JAK inhibitor tofacitinib for treating rheumatoid arthritis: from basic to clinical

Rheumatoid arthritis (RA) is a representative autoimmune disease characterized by chronic and destructive inflammatory synovitis. The multiple cytokines play pivotal roles in RA pathogenesis by inducing intracellular signaling, and members of the Janus kinase (JAK) family are essential for such signal transduction. An orally available JAK3 inhibitor, tofacitinib, has been applied for RA, with satisfactory effects and acceptable safety in multiple clinical examinations. From phase 2 dose-finding studies, tofacitinib 5 mg and 10 mg twice a day appear suitable for further evaluation. Subsequently, multiple phase 3 studies were carried out, and tofacitinib with or without methotrexate (MTX) is efficacious and has a manageable safety profile in active RA patients who are MTX naïve or show inadequate response to methotrexate (MTX-IR), disease-modifying antirheumatic drugs (DMARD)-IR, or tumor necrosis factor (TNF)-inhibitor-IR. The common adverse events were infections, such as nasopharyngitis; increases in cholesterol, transaminase, and creatinine; and decreases in neutrophil counts. Although the mode of action of tofacitinib remains unclear, we clarified that the inhibitory effects of tofacitinib could be mediated through suppression of interleukin (IL)-17 and interferon (IFN)-γ production and proliferation of CD4(+) T cells in the inflamed synovium. Taken together, an orally available kinase inhibitor tofacitinib targeting JAK-mediated signals would be expected to be a new option for RA treatment.

Activity assay of epidermal growth factor receptor tyrosine kinase inhibitors in triple-negative breast cancer cells using peptide-conjugated magnetic beads

Triple-negative breast cancer (TNBC) is a highly aggressive subtype of breast cancer with limited treatment options. Epidermal growth factor receptor I (EGFR) has emerged as a promising target in TNBC. Limited success of the EGFR kinase inhibiting small molecules in clinical trials may be attributed in part to inaccuracy in identifying EGFR signatures in patient tumors. In light of the absence of a simple correlation between EGFR expression and its degree of activation, a simple and reliable tool that can quantify EGFR kinase activity in tumor samples may be of therapeutic value in predicting patient-specific EGFR targeted therapies. This study reports the development of an assay that can quantitatively profile EGFR kinase activities and inhibitor sensitivities in TNBC cell lysates by using peptide reporters covalently tethered to magnetic beads in a controlled orientation. The use of magnetic beads provides rapid sample handling and easy product isolation. The potential of this approach was demonstrated by screening a set of five clinically relevant EGFR tyrosine kinase inhibitors. Formatted for microwell plates, this magnetic bead-based kinase assay may be used as a complementary approach for direct high-throughput screening of small molecule inhibitors.

The immune inhibitory receptor osteoactivin is upregulated in monocyte-derived dendritic cells by BCR-ABL tyrosine kinase inhibitors

Multiple approaches presently aim to combine targeted therapies using tyrosine kinase inhibitors with immunotherapy. Ex vivo-generated dendritic cells are frequently used in such strategies due to their unique ability to initiate primary T-cell immune responses. Besides governing tumor cell growth, many kinases targeted by tyrosine kinase inhibitors are involved in the development and function of dendritic cells and thus tyrosine kinase inhibitor therapy may cause immunoinhibitory side effects. We here report that exposure of developing human monocyte-derived dendritic cells to the BCR-ABL inhibitors imatinib, dasatinib, and nilotinib results in profound upregulation of the transmembrane glycoprotein osteoactivin that has recently been characterized as a negative regulator of T-cell activation. Thus, in line with osteoactivin upregulation, exposure to tyrosine kinase inhibitors resulted in significantly reduced stimulatory capacity of dendritic cells in mixed lymphocyte reactions that could be restored by the addition of blocking anti-osteoactivin antibody. Our data demonstrate that tyrosine kinase inhibitor-mediated inhibition of dendritic cell function is, at least in great part, mediated by upregulation of the immune inhibitory molecule osteoactivin.

The JAK inhibitor tofacitinib regulates synovitis through inhibition of interferon-γ and interleukin-17 production by human CD4+ T cells

OBJECTIVE

Tofacitinib (CP-690,550) is a novel JAK inhibitor that is currently in clinical trials for the treatment of rheumatoid arthritis (RA). The aim of this study was to examine the effects of tofacitinib in vitro and in vivo in RA, in order to elucidate the role of JAK in the disease process.

METHODS

CD4+ T cells, CD14+ monocytes, and synovial fibroblasts (SFs) were purified from the synovium and peripheral blood of patients with RA and were evaluated for the effect of tofacitinib on cytokine production and cell proliferation. For in vivo analysis, synovium and cartilage samples obtained from patients with RA were implanted in immunodeficient mice (SCID-HuRAg mice), and tofacitinib was administered via an osmotic minipump.

RESULTS

Tofacitinib treatment of CD4+ T cells originating from synovium and peripheral blood inhibited the production of interleukin-17 (IL-17) and interferon-γ (IFNγ) in a dose-dependent manner, affecting both proliferation and transcription, but had no effect on IL-6 and IL-8 production. Tofacitinib did not affect IL-6 and IL-8 production by RASFs and CD14+ monocytes. However, conditioned medium from CD4+ T cells cultured with tofacitinib inhibited IL-6 production by RASFs and IL-8 production by CD14+ monocytes. Treatment of SCID-HuRAg mice with tofacitinib decreased serum levels of human IL-6 and IL-8 and markedly suppressed invasion of synovial tissue into cartilage.

CONCLUSION

Tofacitinib directly suppressed the production of IL-17 and IFNγ and the proliferation of CD4+ T cells, resulting in inhibition of IL-6 production by RASFs and IL-8 production by CD14+ cells and decreased cartilage destruction. In CD4+ T cells, presumably Th1 and Th17 cells, JAK plays a crucial role in RA synovitis.

The Bruton tyrosine kinase inhibitor PCI-32765 ameliorates autoimmune arthritis by inhibition of multiple effector cells

INTRODUCTION

The aim was to determine the effect of the Bruton tyrosine kinase (Btk)-selective inhibitor PCI-32765, currently in Phase I/II studies in lymphoma trials, in arthritis and immune-complex (IC) based animal models and describe the underlying cellular mechanisms.

METHODS

PCI-32765 was administered in a series of murine IC disease models including collagen-induced arthritis (CIA), collagen antibody-induced arthritis (CAIA), reversed passive anaphylactic reaction (RPA), and passive cutaneous anaphylaxis (PCA). Clinical and pathologic features characteristic of each model were examined following treatment. PCI-32765 was then examined in assays using immune cells relevant to the pathogenesis of arthritis, and where Btk is thought to play a functional role. These included proliferation and calcium mobilization in B cells, cytokine and chemokine production in monocytes/macrophages, degranulation of mast cells and its subsequent cytokine/chemokine production.

RESULTS

PCI-32765 dose-dependently and potently reversed arthritic inflammation in a therapeutic CIA model with an ED(50) of 2.6 mg/kg/day. PCI-32765 also prevented clinical arthritis in CAIA models. In both models, infiltration of monocytes and macrophages into the synovium was completely inhibited and importantly, the bone and cartilage integrity of the joints were preserved. PCI-32765 reduced inflammation in the Arthus and PCA assays. In vitro, PCI-32765 inhibited BCR-activated primary B cell proliferation (IC(50) = 8 nM). Following FcγR stimulation, PCI-32765 inhibited TNFα, IL-1β and IL-6 production in primary monocytes (IC(50) = 2.6, 0.5, 3.9 nM, respectively). Following FcεRI stimulation of cultured human mast cells, PCI-32765 inhibited release of histamine, PGD(2), TNF-α, IL-8 and MCP-1.

CONCLUSIONS

PCI-32765 is efficacious in CIA, and in IC models that do not depend upon autoantibody production from B cells. Thus PCI-32765 targets not only B lymphocytes but also monocytes, macrophages and mast cells, which are important Btk-expressing effector cells in arthritis.

Comparison of imatinib, nilotinib and silymarin in the treatment of carbon tetrachloride-induced hepatic oxidative stress, injury and fibrosis

Effective and well-tolerated anti-fibrotic drugs are currently lacking. Therefore, this study was carried out to investigate the potential anti-fibrotic effects of imatinib, nilotinib and silymarin on established hepatic fibrosis in the carbon tetrachloride (CCl(4)) rat model. Male Wistar rats received intraperitoneal injections of CCl(4) twice weekly for 8weeks, as well as daily intraperitoneal treatments of imatinib (10 and 20mg/kg), nilotinib (10 and 20mg/kg) and silymarin (100mg/kg) during the last 4weeks of CCl(4)-intoxication. At the end of the study, hepatic damage was evaluated by analysis of liver function tests and hepatic oxidative stress parameters. Hepatic fibrosis was evaluated by histopathology and morphometry, as well as collagen and 4-hydroxyproline contents. Nilotinib (20mg/kg) was the most effective treatment to counteract CCl(4)-induced hepatic injury as indicated by liver function tests and histopathology. Nilotinib (10mg/kg), nilotinib (20mg/kg) and silymarin (100mg/kg) treatments reduced the mean score of hepatic fibrosis by 31%, 68% and 47%, respectively, and hepatic collagen content by 47%, 49% and 18%, respectively in CCl(4)-treated rats. Hepatic morphometric evaluation and 4-hydroxyproline content revealed that CCl(4)-induced fibrosis was ameliorated significantly by nilotinib (20mg/kg) and imatinib (20mg/kg). Unlike nilotinib, imatinib (20mg/kg) showed some sort of hepatic injury evidenced by elevation of serum aminotransferases and total bilirubin levels, and hepatic total nitrate/nitrite content, as well as characteristic anisonucleosis visualized with the hematoxylin-eosin staining. In conclusion, this study provides the evidence that nilotinib exerts anti-fibrotic activity and suggests that it may be valuable in the treatment of hepatic fibrosis in humans.

Photocleavable peptide-conjugated magnetic beads for protein kinase assays by MALDI-TOF MS

Peptides were immobilized onto superparamagnetic beads via photocleavable linkers. This enabled simple, rapid, and label-free protein kinase assays via MALDI-TOF MS detection of substrate peptide phosphorylation. Abltide, a model substrate for the Abl protein tyrosine kinase model, was coupled onto amine-terminated beads, incubated with ATP and recombinant c-Abl kinase, and released and further detected to determine phosphorylation. Abltide phosphorylation was found to depend significantly on the length and composition of linkers to the bead surface. Inserting a diblock spacer of poly(glycine) and poly(ethylene glycol) segments markedly enhanced phosphorylation. To validate the assay, the activity of two small-molecule kinase inhibitors, imatinib and dasatinib, which target the oncogenic mutant tyrosine kinase Bcr-Abl to treat chronic myeloid leukemia (CML), was tested. Examining inhibition of the purified c-Abl or Bcr-Abl in K562 CML cell extracts, IC(50) values were determined to be consistent with the literature. This simple, label-free, MALDI-based protein kinase assay can be readily adapted to allow multiplexed assays of multiple peptide substrates and/or analysis of alternative post-translational modifications as a tool for drug discovery and clinical testing.

Involvement of Src family tyrosine kinase in apoptosis of human neutrophils induced by protozoan parasite Entamoeba histolytica

Tyrosine kinases are one of the most important regulators for intracellular signal transduction related to inflammatory responses. However, there are no reports describing the effects of tyrosine kinases on neutrophil apoptosis induced by Entamoeba histolytica. In this study, isolated human neutrophils from peripheral blood were incubated with live trophozoites in the presence or absence of tyrosine kinase inhibitors. Entamoeba-induced receptor shedding of CD16 and PS externalization in neutrophils were inhibited by pre-incubation of neutrophils with the broad-spectrum tyrosine kinase inhibitor genistein or the Src family kinase inhibitor PP2. Entamoeba-induced ROS production was also inhibited by genistein or PP2. Moreover, genistein and PP2 blocked the phosphorylation of ERK and p38 MAPK in neutrophils induced by E. histolytica. These results suggest that Src tyrosine kinases may participate in the signaling event for ROS-dependent activation of MAPKs during neutrophil apoptosis induced by E. histolytica.