Highly Efficient Oral Iguratimod/Polyvinyl Alcohol Nanodrugs Fabricated by High-Gravity Nanoprecipitation Technique for Treatment of Rheumatoid Arthritis.

Rheumatoid arthritis (RA), a systemic autoimmune disease, poses a significant human health threat. Iguratimod (IGUR), a novel disease-modifying antirheumatic drug (DMARD), has attracted great attention for RA treatment. Due to IGUR's hydrophobic nature, there's a pressing need for effective pharmaceutical formulations to enhance bioavailability and therapeutic efficacy. The high-gravity nanoprecipitation technique (HGNPT) emerges as a promising approach for formulating poorly water-soluble drugs. In this study, IGUR nanodrugs (NanoIGUR) are synthesized using HGNPT, with a focus on optimizing various operational parameters. The outcomes revealed that HGNPT enabled the continuous production of NanoIGUR with smaller sizes (ranging from 300 to 1000 nm), more uniform shapes, and reduced crystallinity. In vitro drug release tests demonstrated improved dissolution rates with decreasing particle size and crystallinity. Notably, in vitro and in vivo investigations showcased NanoIGUR's efficacy in inhibiting synovial fibroblast proliferation, migration, and invasion, as well as reducing inflammation in collagen-induced arthritis. This study introduces a promising strategy to enhance and broaden the application of poorly water-soluble drugs.

Structural optimizations on the 7H-pyrrolo[2,3-d]pyrimidine scaffold to develop highly selective, safe and potent JAK3 inhibitors for the treatment of Rheumatoid arthritis.

Janus Kinase 3 (JAK3) is important for the signaling transduction of cytokines in immune cells and is identified as potential target for treatment of rheumatoid arthritis (RA). Recently, we designed and synthesized two JAK3 inhibitors J1b and J1f, which featured with high selectivity but mild bioactivity. Therefore, in present study the structure was optimized to increase the potency. As shown in the results, most of the compounds synthesized showed stronger inhibitory activities against JAK3 in contrast to the lead compounds, among which 9a was the most promising candidate because it had the most potent effect in ameliorating carrageenan-induced inflammation of mice and exhibited low acute in vivo toxicity (MTD > 2 g/kg). Further analysis revealed that 9a was highly selective to JAK3 (IC50 = 0.29 nM) with only minimal effect on other JAK members (>3300-fold) and those kinases bearing a thiol in a position analogous to that of Cys909 in JAK3 (>150-fold). Meanwhile, the selectivity of JAK3 was also confirmed by PBMC stimulation assay, in which 9a irreversibly bound to JAK3 and robustly inhibited the signaling transduction with mild suppression on other JAKs. Moreover, it was showed that 9a could remarkably inhibited the proliferation of lymphocytes in response to concanavalin A and significantly mitigate disease severity in collagen induced arthritis. Therefore, present data indicate that compound 9a is a selective JAK3 inhibitor and could be a promising candidate for clinical treatment of RA.

Selection and Mechanism Study of Q-Markers for Xanthocerais lignum Anti-Rheumatoid Arthritis Based on Serum Spectrum-Effect Correlation Analysis.

OBJECTIVE: To elucidate the chemical profile of Xanthocerais lignum's extracts of different polarities and their impact on rheumatoid arthritis (RA), we identified anti-RA markers and predicted their action mechanisms. METHODS: A collagen-induced arthritis rat model was established, and UPLC-Q-Exactive Orbitrap MS technology was employed to analyze and identify the chemical constituents within the alcohol extract of Xanthocerais lignum and its various extraction fractions, as well as their translocation into the bloodstream. Serum spectrum-effect correlation analysis was utilized to elucidate the pharmacodynamic material basis of Xanthocerais lignum against RA and to screen for Q-Markers. Finally, the potential anti-RA mechanisms of the Q-Markers were predicted through compound-target interaction data and validated using molecular docking techniques. RESULTS: We identified 71 compounds, with flavan-3-ols and flavanones as key components. Of these, 36 were detected in the bloodstream, including 17 original and 19 metabolized forms. Proanthocyanidin A2, dihydroquercetin, catechin, and epicatechin (plus glucuronides) showed potential anti-RA activity. These compounds, acting as Q-Markers, may modulate ERK, NF-κB, HIF-1α, and VEGF in the HIF-1 pathway. CONCLUSIONS: This research clarifies Xanthocerais lignum's pharmacodynamic material basis against RA, identifies 4 Q-Markers, and offers insights into their mechanisms, aiding quality assessment and lead compound development for RA treatment.

Computer-Aided Drug Design of Novel Derivatives of 2-Amino-7,9-dihydro-8H-purin-8-one as Potent Pan-Janus JAK3 Inhibitors.

Rheumatoid arthritis (RA) remains one of the most prevalent autoimmune diseases worldwide. Janus kinase 3 (JAK3) is an essential enzyme for treating autoimmune diseases, including RA. Molecular modeling techniques play a crucial role in the search for new drugs by reducing time delays. In this study, the 3D-QSAR approach is employed to predict new JAK3 inhibitors. Two robust models, both field-based with R2 = 0.93, R = 0.96, and Q2 = 87, and atom-based with R2 = 0.94, R = 0.97, and Q2 = 86, yielded good results by identifying groups that may readily direct their interaction. A reliable pharmacophore model, DHRRR1, was provided in this work to enable the clear characterization of chemical features, leading to the design of 13 inhibitors with their pIC50 values. The DHRRR1 model yielded a validation result with a ROC value of 0.87. Five promising inhibitors were selected for further study based on an ADMET analysis of their pharmacokinetic properties and covalent docking (CovDock). Compared to the FDA-approved drug tofacitinib, the pharmaceutical features, binding affinity and stability of the inhibitors were analyzed through CovDock, 300 ns molecular dynamics simulations, free energy binding calculations and ADMET predictions. The results show that the inhibitors have strong binding affinity, stability and favorable pharmaceutical properties. The newly predicted molecules, as JAK3 inhibitors for the treatment of RA, are promising candidates for use as drugs.

Epigenetic Suppression of HIV in Myeloid Cells by the BRD4-Selective Small Molecule Modulator ZL0580.

Brain-resident microglia and myeloid cells (perivascular macrophages) are important HIV reservoirs in vivo, especially in the central nervous system (CNS). Despite antiretroviral therapy (ART), low-level persistent HIV replication in these reservoirs remains detectable, which contributes to neuroinflammation and neurological disorders in HIV-infected patients. New approaches complementary to ART to repress residual HIV replication in CNS reservoirs are needed. Our group has recently identified a BRD4-selective small molecule modulator (ZL0580) that induces the epigenetic suppression of HIV. Here, we examined the effects of this compound on HIV in human myeloid cells. We found that ZL0580 induces potent and durable suppression of both induced and basal HIV transcription in microglial cells (HC69) and monocytic cell lines (U1 and OM10.1). Pretreatment of microglia with ZL0580 renders them more refractory to latent HIV reactivation, indicating an epigenetic reprogramming effect of ZL0580 on HIV long terminal repeat (LTR) in microglia. We also demonstrate that ZL0580 induces repressive effect on HIV in human primary monocyte-derived macrophages (MDMs) by promoting HIV suppression during ART treatment. Mechanistically, ZL0580 inhibits Tat transactivation in microglia by disrupting binding of Tat to CDK9, a process key to HIV transcription elongation. High-resolution micrococcal nuclease mapping showed that ZL0580 induces a repressive chromatin structure at the HIV LTR. Taken together, our data suggest that ZL0580 represents a potential approach that could be used in combination with ART to suppress residual HIV replication and/or latent HIV reactivation in CNS reservoirs, thereby reducing HIV-associated neuroinflammation.IMPORTANCE Brain-resident microglia and perivascular macrophages are important HIV reservoirs in the CNS. Persistent viral replication and latent HIV reactivation in the CNS, even under ART, are believed to occur, causing neuroinflammation and neurological disorders in HIV-infected patients. It is critical to identify new approaches that can control residual HIV replication and/or latent HIV reactivation in these reservoirs. We here report that the BRD4-selective small molecule modulator, ZL0580, induces potent and durable suppression of HIV in human microglial and monocytic cell lines. Using an in vitro HIV-infected, ART-treated MDM model, we show that ZL0580 also induces suppressive effect on HIV in human primary macrophages. The significance of our research is that it suggests a potential new approach that has utility in combination with ART to suppress residual HIV replication and/or HIV reactivation in CNS reservoirs, thereby reducing neuroinflammation and neurological disorders in HIV-infected individuals.

Perspectives of Methotrexate-Based Radioagents for Application in Nuclear Medicine.

Methotrexate is a gold standard among disease modifying antirheumatic drugs and is also extensively used clinically in combination with oncological therapies. Thus, it is not surprising that nuclear medicine found an interest in methotrexate in the search for diagnostic and therapeutic solutions. Numerous folate-related radiopharmaceuticals have been proposed for nuclear medicine purposes; however, methotrexate radioagents represent only a minority. This imbalance results from the fact that methotrexate has significantly weaker affinity for folate receptors than folic acid. Nevertheless, radiolabeled methotrexate agents utilized as a tool for early detection and imaging of inflammation in rheumatoid arthritis patients gave promising results. Similarly, the use of multimodal MTX-release nanosystems may find potential applications in radiosynovectomy and theranostic approaches in folate receptor positive cancers.

Design, synthesis and anti-rheumatoid arthritis evaluation of double-ring conjugated enones.

Four series of double-ring conjugated enones were designed, synthesized and studied for the inhibition of synovial cell activity through the modification of Dysodensiol K core structure, double-ring, double-bond and double-carbonyl groups. For in vitro synovial cell assay of rats, compound 151 and 168 exhibited good inhibitory activities, with IC50 values of 2.71 ± 0.18 and 2.68 ± 0.16 µM respectively. At the same time, the LDH release and LD50 test results revealed that the target compounds were low cytotoxicity and acute toxicity. For in vivo CIA model test through the oral administration, compounds 151 and 168 were exhibited similar effect to positive control group methotrexate.

Anti-rheumatic activity of pseudoephedrine (a substituted phenethylamine) in complete Freund's adjuvant-induced arthritic rats by down regulating IL-1ß, IL-6 and TNF-α as well as upregulating IL-4 and IL-10.

Pseudoephedrine (substituted phenethylamine) is well known as psychotic and bronchodilator. Numerous studies on phenethylamine derivatives indicated that these agents have the potential to abolish inflammatory responses in the non-biological and biological systems. These facts provided the basis to conduct a study on pseudoephedrine to explore its therapeutics in Complete Freund's Adjuvant (CFA)-induced arthritis. Furthermore, existing treatment approaches for RA associated with limited effect on chronic immunological models. Real-time polymerase chain reaction (q-PCR) was performed to execute the expression of pro and anti-inflammatory cytokines in treated and non-treated arthritic rats. These findings were further co investigate by histological observations. The paw volume, paw diameter, weight variations and arthritic score were determined at specific days throughout the experiment of 28 days. Pseudoephedrine at all doses significantly (p < 0.001) suppressed the expression of PGE2, TNF-α, IL-1ß and IL-6. Moreover, pseudoephedrine (20 and 40 mg/kg) caused significant augmentation of IL-4 and IL-10. Similarly, the drug expressed a significant anti-arthritic effect by reducing the paw volume, paw diameter and arthritic score. Similarly, it also reverts the reduction in body weight of arthritic rats at all above-mentioned doses. These findings supported the anti-arthritic potential of pseudoephedrine and recommended it for clinical trials.

Identification and Quantification of Oxidation Products in Full-Length Biotherapeutic Antibodies by NMR Spectroscopy.

Therapeutic proteins are an indispensable class of drugs and often therapeutics of last resort. They are sensitive to oxidation, which is of critical concern, because it can affect drug safety and efficacy. Protein oxidation, with methionine and tryptophan as the most susceptible moieties, is mainly monitored by HPLC-MS techniques. However, since several oxidation products display the same mass difference, their identification by MS is often ambiguous. Therefore, an alternative analytical method able to unambiguously identify and, ideally, also quantify oxidation species in proteins is highly desired. Here, we present an NMR-based approach to monitor oxidation in full-length proteins under denaturing conditions, as demonstrated on two biotherapeutic monoclonal antibodies (mAbs). We show that methionine sulfoxide, methionine sulfone, N-formylkynurenine, kynurenine, oxindolylalanine, hydroxypyrroloindole, and 5-hydroxytryptophan result in characteristic chemical shift correlations suited for their identification and quantification. We identified the five most abundant oxidation products in forced degradation studies of two full-length therapeutic mAbs and can also unambiguously distinguish oxindolylalanine from 5-hydroxytryptophan, which are undistinguishable by MS due to the same mass shift. Quantification of the abundant methionine sulfoxide by NMR and MS gave highly comparable values. These results underline the suitability of NMR spectroscopy for the identification and quantification of critical quality attributes of biotherapeutics.

Localization of Therapeutic Fab-CHP Conjugates to Sites of Denatured Collagen for the Treatment of Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation in synovial joints and protease-induced cartilage degradation. Current biologic treatments for RA can effectively reduce symptoms, primarily by neutralizing the proinflammatory cytokine TNFα; however, continued, indiscriminate overinhibition of inflammatory factors can significantly weaken the host immune system, leading to opportunistic infections and interrupting treatment. We hypothesize that localizing anti-TNFα therapeutics to denatured collagen (dCol) present at arthritic joints, via conjugation with collagen-hybridizing peptides (CHPs), will reduce off-site antigen binding and maintain local immunosuppression. We isolated the antigen-binding fragment of the clinically approved anti-TNFα therapeutic infliximab (iFab) and prepared iFab-CHP conjugates via lysine-based conjugation with an SMCC linker. After successful conjugation, confirmed by LC-MS, the binding affinity of iFab-CHP was characterized by ELISA-like assays, which showed comparable antigen binding relative to infliximab, comparable dCol binding relative to CHP, and the hybrid ability to bind both dCol and TNFα simultaneously. We further demonstrated localization of Fab-CHP to areas of high dCol in vivo and promising therapeutic efficacy, assessed by histological staining (Safranin-O and H&E), in a pilot mouse study.

Auxiliary in vitro and in vivo biological evaluation of hydrogen peroxide sensitive prodrugs of methotrexate and aminopterin for the treatment of rheumatoid arthritis.

Rheumatoid arthritis (RA) is a chronic inflammatory disease that causes severe joints damage and other extra-articular alterations. Despite the efficacy of low-dose methotrexate (LD-MTX) in RA treatment, adverse effects are the predominant reasons for discontinuation of therapy. As a therapeutic targeting strategy, the presence of increased concentrations of reactive oxygen species (ROS) in the inflammatory environment can serve as the stimulus for prodrug activation in site-selective drug delivery systems. Our group has previously reported novel ROS sensitive prodrugs (1-3) of MTX and aminopterin (AMT) for site-selective delivery to inflammatory tissue associated with RA, with the aim of reducing side effects in RA therapy. Herein, we investigate the effect and toxicity of the same prodrugs in a rat CIA (collagen-induced arthritis) model of RA. We find that prodrug 1, an arylboronic acid ROS-sensitive MTX-prodrug, displays similar in vivo efficacy as MTX at an equimolar dose, while avoiding adverse effects known to restrict MTX treatment. To further characterize prodrug 1 and its ROS mediated activation, we synthesized compound 4, a negative control lacking the boronic acid moiety. We then investigated the effect of molecules on cell proliferation and cytotoxicity in the presence of the ROS scavenger pyruvate, as well as their stability in buffer and cell media, demonstrating a direct correlation between ROS concentration and the prodrug activity. Moreover, the in vitro ADME properties were investigated, including permeability, rat plasma and microsomal stability.

Discovery of diaminopyrimidine-carboxamide derivatives as JAK3 inhibitors.

Selective inhibition of janus kinase (JAK) has been identified as an important strategy for the treatment of autoimmune disorders. Optimization at the C2 and C4-positions of pyrimidine ring of Cerdulatinib led to the discovery of a potent and orally bioavailable 2,4-diaminopyrimidine-5-carboxamide based JAK3 selective inhibitor (11i). A cellular selectivity study further confirmed that 11i preferentially inhibits JAK3 over JAK1, in JAK/STAT signaling pathway. Compound 11i showed good anti-arthritic activity, which could be correlated with its improved oral bioavailability. In the repeat dose acute toxicity study, 11i showed no adverse changes related to gross pathology and clinical signs, indicating that the new class JAK3 selective inhibitor could be viable therapeutic option for the treatment of rheumatoid arthritis.

Amentadione from the Alga Cystoseira usneoides as a Novel Osteoarthritis Protective Agent in an Ex Vivo Co-Culture OA Model.

Osteoarthritis (OA) remains a prevalent chronic disease without effective prevention and treatment. Amentadione (YP), a meroditerpenoid purified from the alga Cystoseira usneoides, has demonstrated anti-inflammatory activity. Here, we investigated the YP anti-osteoarthritic potential, by using a novel OA preclinical drug development pipeline designed to evaluate the anti-inflammatory and anti-mineralizing activities of potential OA-protective compounds. The workflow was based on in vitro primary cell cultures followed by human cartilage explants assays and a new OA co-culture model, combining cartilage explants with synoviocytes under interleukin-1ß (IL-1ß) or hydroxyapatite (HAP) stimulation. A combination of gene expression analysis and measurement of inflammatory mediators showed that the proposed model mimicked early disease stages, while YP counteracted inflammatory responses by downregulation of COX-2 and IL-6, improved cartilage homeostasis by downregulation of MMP3 and the chondrocytes hypertrophic differentiation factors Col10 and Runx2. Importantly, YP downregulated NF-κB gene expression and decreased phosphorylated IkBα/total IkBα ratio in chondrocytes. These results indicate the co-culture as a relevant pre-clinical OA model, and strongly suggest YP as a cartilage protective factor by inhibiting inflammatory, mineralizing, catabolic and differentiation processes during OA development, through inhibition of NF-κB signaling pathways, with high therapeutic potential.

Active Ingredients and Anti-Arthritic Mechanisms of Ba-Wei-Long-Zuan Granule Revealed by 1 H-NMR-Based Metabolomics Combined with Network Pharmacology Analysis.

Ba-Wei-Long-Zuan granule (BWLZ) is a traditional herbal preparation. It has been widely used for the treatment of rheumatoid arthritis (RA). However, its active ingredients and mechanisms of action are still unclear. The present study aims to reveal the active compounds and anti-arthritic mechanisms of BWLZ against collagen-induced arthritis (CIA) by using 1 H-NMR-based metabolomics, molecular docking and network pharmacology methods. After 30 days of administration, BWLZ could effectively improve the metabolic disorders in CIA rats. The anti-arthritic effect of BWLZ was related to its restoration of 16 disturbed serum metabolites. Molecular docking and network analysis showed that 20 compounds present in BWLZ could act on multiple targets. Among them, coclaurine and hesperidin showed the highest hit rates for target proteins related to both metabolic regulation and RA, indicating that these two compounds might be potential active ingredients of BWLZ. Moreover, pathway enrichment analysis suggested that the anti-arthritic mechanisms of BWLZ might be attributed to its network regulation of several biological processes, such as steroid hormone biosynthesis, mTOR signaling pathway, alanine, aspartate and glutamate metabolism, and synthesis and degradation of ketone bodies. These results provide further evidence for the anti-arthritic properties of BWLZ and are beneficial for its quality control and clinical application. The potential targets and biological processes found in this study may provide valuable information for further studying the molecular mechanisms of BWLZ against RA. In addition, our work provides new insights for revealing the active ingredients and regulatory mechanisms of complex herbal preparations.

Discovery of Tricyclic Pyranochromenone as Novel Bruton's Tyrosine Kinase Inhibitors with in Vivo Antirheumatic Activity.

Bruton's tyrosine kinase (BTK) is an attractive target for treating patients with B cell malignancies and autoimmune diseases. Many BTK inhibitors have been identified; however, like other kinase inhibitors, they lack diversity in their core structures. Therefore, it is important to secure a novel scaffold that occupies the adenine-binding site of BTK. We screened an in-house library of natural products and their analogs via a biochemical assay to identify a novel scaffold for targeting BTK. A pyranochromenone scaffold, derived from a natural active component decursin, was found to be effective at targeting BTK and was selected for further optimization. A series of pyranochromenone analogs was synthesized through the modification of pyranochromenone at the C7 position. Pyranochromenone compounds with an electrophilic warhead exhibited promising BTK inhibitory activity, with IC50 values in the range of 0.5-0.9 µM. A docking study of the representative compound 8 provided a reasonable explanation for compound activity. Compound 8 demonstrated good selectivity over other associated kinases and decreased the production of proinflammatory cytokines in THP cells. Moreover, compound 8 presented significant in vivo efficacy in a murine model of collagen-induced arthritis.

Food-Derived Nanoscopic Drug Delivery Systems for Treatment of Rheumatoid Arthritis.

Rheumatoid arthritis (RA) is a severe systemic inflammatory disease with no cure at present. Recent developments in the understanding of inflammation and nanomaterial science have led to increased applications of nanostructured drug delivery systems in the treatment of RA. The present review summarizes novel fabrications of nanoscale drug carriers using food components as either the delivered drugs or carrier structures, in order to achieve safe, effective and convenient drug administration. Polyphenols and flavonoids are among the most frequently carried anti-RA therapeutics in the nanosystems. Fatty substances, polysaccharides, and peptides/proteins can function as structuring agents of the nanocarriers. Frequently used nanostructures include nanoemulsions, nanocapsules, liposomes, and various nanoparticles. Using these nanostructures has improved drug solubility, absorption, biodistribution, stability, targeted accumulation, and release. Joint vectorization, i.e., using a combination of bioactive molecules, can bring elevated therapeutic outcomes. Utilization of anti-arthritic chemicals that can self-assemble into nanostructures is a promising research orientation in this field.

Synthesis, Molecular Docking, and In Vitro Boron Neutron Capture Therapy Assay of Carboranyl Sinomenine.

In comparison with pristine sinomenine and carborane precursors, the calculations of molecular docking with matrix metalloproteinases (MMPs) and methylcarboranyl-n-butyl sinomenine showed improved interactions. Accordingly, methylcarboranyl-n-butyl sinomenine shows a high potential in the treatment of rheumatoid arthritis (RA) in the presence of slow neutrons. The reaction of potassium salt of sinomenie, which is generated from the deprotonation of sinomenine (1) using potassium carbonate in a solvent of N,N-dimethyl formamide, with 4-methylcarboranyl-n-butyl iodide, (2) forms methylcarboranyl-n-butyl sinomenine (3) in 54.3% yield as a new product. This new compound was characterized by 1H, 13C, and 11B NMR spectroscopy, FT-IR spectroscopy, and elemental analyses to confirm its molecular composition. In addition to molecular docking interactions with MMPs, the in vitro killing effects of 3, along with its toxicity measurements, exhibited its potential to be the new drug delivery agent for boron neutron capture synovectomy (BNCS) and boron neutron capture therapy (BNCT) for the treatment of rheumatoid arthritis (RA) and cancers in the presence of slow neutrons, respectively.

[Small molecules treatment in rheumatoid arthritis]. / Petites molécules dans la polyarthrite rhumatoïde.

If treatment target is not reached with a conventional disease-modifying antirheumatic drug (csDMARD) such as methotrexate in rheumatoid arthritis, it is recommended to use a biologic (bDMARD) or a Janus kinase (JAK) inhibitor, small synthetic molecules recently developed. Oral administration and short half-life can favour the choice of JAK inhibitors, as well as the opportunity to use it in monotherapy, even though co-treatment with csDMARD is recommended. As yet long-term studies are lacking, little is known about adverse effects although risk of herpes virus infections is clearly higher with JAK inhibitors than bDMARD treatments.

Lors du contrôle insuffisant de l'activité de la polyarthrite rhumatoïde (PR) par traitement conventionnel (csDMARD) comme le méthotrexate, il est recommandé d'introduire un traitement biologique (bDMARD) ou un inhibiteur de Janus kinase (JAK). Ces derniers sont de petites molécules synthétiques récemment développées. La prise per os et une demi-vie courte peuvent favoriser le choix d'un inhibiteur de JAK. De plus, une utilisation en monothérapie est envisageable, bien qu'une association avec un csDMARD soit préférée. En raison d'un manque d'études à long terme, leurs effets indésirables sont peu connus, hormis les infections à virus herpétique qui sont plus élevées qu'avec les bDMARD.

Profiling drugs for rheumatoid arthritis that inhibit synovial fibroblast activation.

Activation of synovial fibroblasts (SFs) contributes to rheumatoid arthritis (RA) by damaging synovial membranes and generating inflammatory cytokines that recruit immune cells to the joint. In this paper we profile cytokine secretion by primary human SFs from healthy tissues and from donors with RA and show that SF activation by TNF, IL-1α, and polyinosinic-polycytidylic acid (Poly(I:C)) cause secretion of multiple cytokines found at high levels in RA synovial fluids. We used interaction multiple linear regression to quantify therapeutic and countertherapeutic drug effects across activators and donors and found that the ability of drugs to block SF activation was strongly dependent on the identity of the activating cytokine. (5z)-7-oxozeaenol (5ZO), a preclinical drug that targets transforming growth factor-ß-activated kinase 1 (TAK1), was more effective at blocking SF activation across all contexts than the approved drug tofacitinib, which supports the development of molecules similar to 5ZO for use as RA therapeutics.

Metabolic Activation of Tofacitinib Mediated by Myeloperoxidase in Vitro.

Tofacitinib (TFT) is used for the treatment of moderately and severely active rheumatoid arthritis. Unfortunately, TFT was reported to induce leukopenia, and the underlying mechanisms remain unclear. The present study demonstrated that TFT was oxidized to a chemically reactive nitrenium ion by myeloperoxidase (MPO) occurring in neutrophils. The electrophilic ion showed chemical reactivity toward N-acetyl-cysteine (NAC) to produce two TFT-NAC conjugates (M1 and M2) in incubation of TFT with leucocytes in the presence of NAC. The generation of the nitrenium ion was verified by HClO-mediated oxidation of TFT. In addition, the nitrenium ion was found to react with sulfhydryl groups of cysteine residues of cellular protein in leucocytes after exposure to TFT. The study facilitates the understanding of the mechanisms of TFT toxic action.