JAK Inhibitors Research Articles

Therapy outcomes of IL-17 and JAK inhibitors in rosacea: A systematic review.

Therapy outcomes of IL-17 and JAK inhibitors in rosacea: A systematic review.

Exploration of Potential Anti-inflammatory cum Anti-Rheumatoid-arthritis Phyto-molecule through Integrated Green Approach: Network Pharmacology, Molecular Docking, Molecular dynamics, In-vitro and Ex-vivo study.

Rheumatoid arthritis (RA) and associated inflammatory complications are the most prevalent illnesses and can turn into fatal conditions if left untreated. Allopathic medicine is not satisfactory for curing RA. Scientific literature reports reveal that several phyto-compounds viz. flavonoids, saponins, and terpenoids, can heal joints and organs from auto-inflammatory rheumatoid arthritis and pain. Gene ontology, gene network analysis, molecular clustering, and literature review were used to optimise RA-specific highly expressed genes. In-silico molecular docking was performed to short-out potential phytomolecules (Neohesperidin dihydrochalcone (NHDC)) from 1000 datasets-library against RA and validate using MD simulation running at 100 ns. In-vitro anti-inflammatory assays of NHDC inhibited egg-albumin denaturation, IC50 of 47.739 ± 0.51 µg/ml. The ex-vivo MTT assay with NHDC rendered 67.209% inhibition at 100 µM against fd-FLS-cells. NHDC downregulated pro-inflammatory cytokine IL-17A production by 61.11% and 50% at 300 and 200 μM, respectively. Thus, this Studies recommend that NHDC may be highlighted as a novel multi-target PADI4 and JAK3 inhibitor with better efficacy and minimal toxicity in RA warranted to In-Vivo and clinical investigation. The current findings have uncovered remarkable genes and signalling pathways linked to RA, which could enhance our existing comprehension of the molecular mechanisms that drive its development and progression.

Alopecia areata does not increase the risk of venous thromboembolism: an All of Us case-control study.

Alopecia areata (AA) is an autoimmune disease driven by cytokine dysregulation resulting in hair loss, and recent data suggests inflammation may be occurring systemically. This systemic increase in inflammatory cytokines may increase the incidence of thrombotic events, including deep vein thrombosis, stroke, myocardial infarction, and pulmonary embolism. As the use of JAK inhibitors for AA becomes more common, it is important to further investigate this potential relationship to prevent exacerbation of such events. The purpose of this case-control study was to determine if there is an increased association between thrombotic events and alopecia areata using the All of Us database. We matched 926 patients with AA 4:1 to controls without any alopecia, and we found that there was a statistically significant increase in the incidence of venous thromboembolism (VTE) in patients with AA (p = 0.009). Multivariable conditional logistic regression was then used to estimate the odds of AA in relation to VTE, controlling for common hypercoagulable factors (atrial fibrillation, estrogen replacement, obesity, malignancy, pregnancy, and smoking history). We found that after controlling for these risk factors, there was no significant difference in the incidence in VTE between those with and without AA (OR: 1.549, CR 95% (0.862, 2.783)). While recent reports have suggested alopecia areata to be significantly associated with venous thromboembolisms, we did not observe a significant association after controlling for hypercoagulable factors.

The treatment of Tofacitinib for rosacea through the inhibition of the JAK/STAT signaling pathway.

Rosacea is a chronic inflammatory skin disease characterized by facial erythema and telangiectasia. Despite ongoing research, the pathogenesis of rosacea remains incompletely understood, and current therapies are not entirely satisfactory. The JAK/STAT signaling pathway plays an essential role in immunoregulation, inflammation, and neurovascular regulation. Inhibition of the JAK/STAT pathway appears to hold promise as a potential therapy for rosacea. This study aimed to investigate the effects of the JAK inhibitor tofacitinib on rosacea and to preliminarily explore its therapeutic mechanism. To this end, a rosacea-like mouse model was induced using LL37 and treated with a 2% tofacitinib emulsion. The results demonstrated that topical application of tofacitinib significantly ameliorated rosacea-like phenotype, reduced the infiltration of CD4+ T cells and mast cells, and suppressed dermal angiogenesis. RT-qPCR analysis revealed a reduction in mRNA expression levels of STAT1, STAT4, and STAT5a in skin lesions following topical tofacitinib treatment. Additionally, three patients diagnosed with erythematotelangiectatic rosacea (ETR) were included in the study and treated with oral tofacitinib, leading to a significant improvement in erythema and flushing symptoms. These findings collectively suggest that tofacitinib alleviates LL37-induced rosacea-like skin inflammation in mice and rosacea skin lesions by inhibiting the JAK/STAT signaling pathway.

Immunophenotyping and Therapeutic Insights from Chronic Mucocutaneous Candidiasis Cases with STAT1 Gain-of-Function Mutations.

Heterozygous STAT1 Gain-of-Function (GOF) mutations are the most common cause of chronic mucocutaneous candidiasis (CMC) among Inborn Errors of Immunity. Clinically, these mutations manifest as a broad spectrum of immune dysregulation, including autoimmune diseases, vascular disorders, and malignancies. The pathogenic mechanisms of immune dysregulation and its impact on immune cells are not yet fully understood. In treatment, JAK inhibitors have shown therapeutic effectiveness in some patients. We analyzed clinical presentations, cellular phenotypes, and functional impacts in five Taiwanese patients with STAT1 GOF. We identified two novel GOF mutations in 5 patients from 2 Taiwanese families, presenting with symptoms of CMC, late-onset rosacea, and autoimmunity. The enhanced phosphorylation and delayed dephosphorylation were displayed by the patients' cells. There are alterations in both innate and adaptive immune cells, including expansion of CD38+HLADR +CD8+ T cells, a skewed activated Tfh cells toward Th1, reduction of memory, marginal zone and anergic B cells, all main functional dendritic cell lineages, and a reduction in classical monocyte. Baricitinib showed therapeutic effectiveness without side effects. Our study provides the first comprehensive clinical and molecular characteristics in STAT1 GOF patient in Taiwan and highlights the dysregulated T and B cells subsets which may hinge the autoimmunity in STAT1 GOF patients. It also demonstrated the therapeutic safety and efficacy of baricitinib in pediatric patient. Further research is needed to delineate how the aberrant STAT1 signaling lead to the changes in cellular populations as well as to better link to the clinical manifestations of the disease.

Effectiveness of Zhengqing Fengtongning in combination with routine rheumatoid arthritis treatment: A real-world multicenter retrospective study

BackgroundZhengqing Fengtongning (ZF) is a modern traditional Chinese medicine preparation used to treat rheumatoid arthritis (RA). In this study, we aimed to prove the effectiveness of ZF in combination with routine RA treatment in the real world. MethodsThis was a retrospective study including 3877 RA patients in multi-centers from August 2015 to April 2023. The experimental group received ZF and the control group received other RA regimens. Propensity score matching was used to eliminate bias. The effectiveness of ZF in combination with routine RA treatment was evaluated through DAS28, ESR, CRP and RF. ResultsThe effectiveness of combining ZF with methotrexate (MTX), iguratimod (IGU), leflunomide (LEF), MTX + LEF, and MTX + nonsteroidal anti-inflammatory drugs in treating RA was significantly better than that of not combining ZF (p < 0.05). The effectiveness of combining ZF was significantly better than that of combining total glucosides of paeony, Kunxian capsule, or Biqi capsule (p < 0.05). No significant difference existed in effectiveness among MTX, IGU, and ZF combined with JAK inhibitor or TNF-ɑ inhibitor (p > 0.05). ConclusionsThis study provides evidence that the effectiveness of MTX, IGU, LEF, MTX + LEF, and MTX + NSAIDs combined with ZF in treating RA was better than those without ZF.

Identifying disease-modifying potential in myelofibrosis clinical trials

AbstractThe ultimate goal of bringing most new drugs to the clinic in hematologic malignancy is to improve overall survival. However, the use of surrogate end points for overall survival is increasingly considered standard practice, because a well validated surrogate end point can accelerate the outcome assessment and facilitate better clinical trial design. Established examples include monitoring minimal residual disease in chronic myeloid leukemia and acute leukemia, and metabolic response assessment in lymphoma. However, what happens when a clinical trial end point that is not a good surrogate for disease-modifying potential becomes ingrained as an expected outcome, and new agents are expected or required to meet this end point to demonstrate “efficacy”? Janus kinase (JAK) inhibitors for myelofibrosis (MF) have a specific impact on reducing symptom burden and splenomegaly but limited impact on the natural history of the disease. Since the introduction of ruxolitinib more than a decade ago there has been modest incremental success in clinical trials for MF but no major leap forward to alter the natural history of the disease. We argue that the clinical development of novel agents for MF will be accelerated by moving away from using end points that are specifically tailored to measure the beneficial effects of JAK inhibitors. We propose that specific measures of relevant disease burden, such as reduction in mutation burden as determined by molecular end points, should replace established end points. Careful reanalysis of existing data and trials in progress is needed to identify the most useful surrogate end points for future MF trials and better serve patient interest.

JAK inhibition in Down Syndrome Regression Disorder

Down Syndrome Regression Disorder (DRSD) is an uncommon but devastating condition affecting primarily adolescents and young adults with Down syndrome (DS). Individuals with DS display a dysregulated immune system associated with hyperactive interferon signaling, which is associated with a high incidence of autoimmune conditions. While the cause of DSRD is unknown, increasing evidence indicates that it may have an immune basis, and some individuals with DSRD have responded to intravenous immunoglobulin therapy. This case series describes three individuals with probable DSRD who received the JAK inhibitor tofacitinib and saw improvement in DSRD symptoms across multiple domains of neurological function.

Glucocorticoid sparing effect of Janus Kinase inhibitors compared to biological Disease Modifying Anti-Rheumatic Drugs in rheumatoid arthritis, a single-center retrospective analysis.

Glucocorticoid sparing in rheumatoid arthritis (RA) treatment is crucial to minimizing adverse effects associated with long-term use. Janus kinase inhibitors (JAKi) could potentially offer a more potent glucocorticoid-sparing effect than biological Disease-Modifying Antirheumatic Drugs (bDMARDs). This is a single-center retrospective analysis of RA patients treated with JAKi or bDMARDs. Glucocorticoid tapering, rescue therapy and discontinuation were analyzed through mixed-effects models, Poisson regression, and multivariable logistic regression, respectively, adjusting for baseline disease activity, demographic factors, and treatment line. A total of 716 RA patients treated with JAKi (n = 156) or bDMARDs (n = 560) were evaluated. JAKi treatment was associated with a more rapid reduction in glucocorticoid dose within the first 6 months and 60% higher odds of discontinuation compared with bDMARDs (adjusted odds ratio 1.63, 95% CI 1.02-2.60, p 0.039). Despite a higher baseline glucocorticoid dose, over 50% of JAKi-treated patients discontinued glucocorticoids after 12 months, vs ∼40% for bDMARDs. The need for glucocorticoid rescue therapy was significantly higher in the bDMARD group (rate ratio 2.66 (95% CI, 1.88-3.74)). Our findings indicate that JAK inhibitors facilitate more rapid glucocorticoid tapering compared with bDMARDs in RA patients. These results underscore the potential of JAK inhibitors to reduce long-term glucocorticoid exposure, highlighting their value in RA management strategies, including minimizing glucocorticoid-related adverse effects.

JAK Inhibitors - Pros and Cons Learned from Their Use in Rheumatic Diseases

JAK Inhibitors - Pros and Cons Learned from Their Use in Rheumatic Diseases

Real-world experience of using dupilumab and JAK inhibitors to manage pruritus in epidermolysis bullosa pruriginosa.

Epidermolysis bullosa pruriginosa (EBP) is a form of dystrophic EB associated with severe pruritus and has skewed Th2 inflammation. Our study suggests that JAK inhibitors may offer superior efficacy compared to dupilumab in treating EBP. Moreover, JAK inhibitors downregulate JAK-STAT signalling and Th1/2 cell differentiation in lesional skin while not in peripheral blood.

Targeting treatment resistance: unveiling the potential of RNA methylation regulators and TG-101,209 in pan-cancer neoadjuvant therapy

BackgroundTumor recurrence and mortality rates remain challenging in cancer patients despite comprehensive treatment. Neoadjuvant chemotherapy and immunotherapy aim to eliminate residual tumor cells, reducing the risk of recurrence. However, drug resistance during neoadjuvant therapy is a significant hurdle. Recent studies suggest a correlation between RNA methylation regulators (RMRs) and response to neoadjuvant therapy.MethodsUsing a multi-center approach, we integrated advanced techniques such as single-cell transcriptomics, whole-genome sequencing, RNA sequencing, proteomics, machine learning, and in vivo/in vitro experiments. Analyzing pan-cancer cohorts, the association between neoadjuvant chemotherapy/immunotherapy effectiveness and RNA methylation using single-cell sequencing was investigated. Multi-omics analysis and machine learning algorithms identified genomic variations, transcriptional dysregulation, and prognostic relevance of RMRs, revealing distinct molecular subtypes guiding pan-cancer neoadjuvant therapy stratification.ResultsOur analysis unveiled a strong link between neoadjuvant therapy efficacy and RNA methylation dynamics, supported by pan-cancer single-cell sequencing data. Integration of omics data and machine learning algorithms identified RMR genomic variations, transcriptional dysregulation, and prognostic implications in pan-cancer. High-RMR-expressing tumors displayed increased genomic alterations, an immunosuppressive microenvironment, poorer prognosis, and resistance to neoadjuvant therapy. Molecular investigations and in vivo/in vitro experiments have substantiated that the JAK inhibitor TG-101,209 exerts notable effects on the immune microenvironment of tumors, rendering high-RMR-expressing pan-cancer tumors, particularly in pancreatic cancer, more susceptible to chemotherapy and immunotherapy.ConclusionsThis study emphasizes the pivotal role of RMRs in pan-cancer neoadjuvant therapy, serving as predictive biomarkers for monitoring the tumor microenvironment, patient prognosis, and therapeutic response. Distinct molecular subtypes of RMRs aid individualized stratification in neoadjuvant therapy. Combining TG-101,209 adjuvant therapy presents a promising strategy to enhance the sensitivity of high-RMR-expressing tumors to chemotherapy and immunotherapy. However, further validation studies are necessary to fully understand the clinical utility of RNA methylation regulators and their impact on patient outcomes.

Efficacy and Safety of Upadacitinib for Axial Spondyloarthritis: A Systematic Review and Meta-Analysis.

Upadacitinib, a selective JAK1 inhibitor, has demonstrated promising results in the treatment of axial Spondyloarthritis (AxSpA). AxSpA management remains challenging since there is a gap in knowledge regarding the potential effect of upadacitinib in axSpA patients. Exploring novel therapeutic options is crucial. Therefore, we performed this systematic review and meta-analysis to summarize and synthesize results collected from available randomized-- controlled trials (RCTs) about the efficacy and safety of upadacitinib for patients with axSpA. A systematic literature search of Medline via PubMed, Web of Science, Scopus, EBSCO, and Cochrane Central was conducted in October 2023. Relevant RCTs were selected, and their data were extracted and analyzed using the RevMan 5.4 software. The main outcomes were assessment in Spondylarthritis International Society (ASAS) 20, ASAS40, SPARCC MRI sacroiliac joint, and Bath Ankylosing Spondylitis disease activity index (BASDAI) 50. Three RCTs with a total of 920 participants were included in this study. Upadacitinib showed significant improvement in the ASAS40 response, ASAS20 response, BASDAI50 response, and SPARCC MRI Sacroiliac Joint change from baseline compared to placebo at 14-week duration (RR 2.19, 95% CI (1.79 to 2.68), P < 0.00001), (RR 1.62, 95% CI [1.42 to 1.84), P < 0.00001), (RR 2.16, 95% CI (1.75 to 2.67), P < 0.00001), and (MD -3.32 points, 95% CI (-3.96 to -2.68), P < 0.00001) respectively. However, this efficacy decreased after the 52-week duration in terms of ASAS40 RR 2.19 vs. 1.02, ASAS20 RR 1.62 vs. 0.98, BASDAI 50 RR 2.16 vs. 1.05, and ASAS Partial Remission RR 3.82 vs. 1.07. Upadacitinib 15 mg showed satisfactory and promising efficacy in the treatment of AxSpA, with no difference in safety profile compared to the placebo.

Hepatitis B reactivation in PsA patients: an SLR and meta-analysis for IL-17, IL-23 and JAK inhibitors.

Hepatitis B reactivation (HBVr) constitutes a side effect of the treatment of autoimmune rheumatic diseases. Even though HBVr risk of conventional synthetic disease modifying anti-rheumatic drugs (csDMARDs) and anti-tumor necrosis factor (anti-TNF) agents has long been established, the risk of targeted synthetic (ts)DMARDs and anti-interleukin (anti-IL) agents remains largely unknown. We conducted a SLR (PubMed, Scopus and EMBASE) and metanalysis to examine the HBVr risk for the following: anti-IL17, anti-IL12/23, anti-IL23 and JAK-inhibitors in patients with chronic HBV infection (HBsAg presence or detectable HBV-DNA) and in patients with prior HBV infection (HBcAb-positive and HBsAg-negative). Meta-analysis was performed using both the fixed and random effects method and was conducted using the R computing language. Overall, our study revealed a low HBVr risk of < 6% in all agents; the risk was significantly higher for people having chronic compared with those with resolved HBV (14,4% vs 5.1%, respectively p< 0.01). There was no difference among different drugs in the HBVr rates [anti-IL-17: 4% (95% CI: 1-9%), anti-IL-12/IL-23: 2% (95% CI: 0-5%), JAK-inhibitors: 4% (95% CI: 1-8%), anti-IL23: 0%]. Of note, HBVr rate reached 28% in patients with chronic HBV who did not receive anti-viral treatment. For patients with resolved hepatitis the respective percentage was 4.7%. Overall, our meta-analysis shows that patients with chronic HBV receiving anti-IL-17, anti-IL-12/23, anti-IL-23 and JAK-inhibitors have significant risk for HBVr, especially if they are not under anti-viral treatment. In contrast, resolved HBV seems to offer minor risk for HBVr even without anti-viral treatment.

Evaluation of the Efficacy of Tofacitinib, a JAK Inhibitor, in Alleviating Sepsis-Induced Multiple Organ Dysfunction Syndrome.

Sepsis, a life-threatening condition triggered by an uncontrolled response to infection, results in a systemic inflammatory response syndrome (SIRS) and the failure of multiple organs leading to multiple organ dysfunction (MODS). In the present study, we investigated the therapeutic potential of tofacitinib (TOFA), an FDA-approved inhibitor of JAK1 and JAK3 against sepsis, using a mouse model induced by cecal ligation puncture (CLP). Swiss albino mice were employed to replicate the CLP-induced sepsis model and were randomly divided into four groups: control, CLP, 150 mg/kg TOFA, and 300 mg/kg TOFA. Six hours after the last TOFA dose, we collected blood and tissue samples from the liver, lungs, kidneys, and spleen for histological analysis. Blood samples were used to assess granulocyte and lymphocyte percentages. Throughout the experiment, we monitored body weight and short-term survival. Our comparative histological analysis revealed that 150 mg/kg TOFA had a protective effect against multiple organ damage. Conversely, the study highlighted the harmful effects of 300 mg/kg TOFA, primarily due to liver and renal toxicity within this group. In summary, our findings demonstrate that tofacitinib at an optimal dose of 150 mg/kg showed promise as a potential therapeutic intervention for sepsis-induced multiple organ failure. However, caution is warranted when considering higher dosages.

A meta-analysis of therapeutic trials of topical ruxolitinib cream for the treatment of vitiligo: therapeutic efficacy, safety, and implications for therapeutic practice.

Vitiligo, an autoimmune condition characterized by depigmented skin patches due to the loss of functional melanocytes, has been linked to dysregulation in the JAK-STAT signaling pathway, particularly in IFN-g signaling. The use of JAK inhibitors, such as ruxolitinib cream, a JAK1 and JAK2 inhibitor, presents a promising approach for vitiligo treatment. This study aims to systematically assess the effectiveness and safety of ruxolitinib cream in patients with vitiligo. We conducted a systematic review and meta-analysis following PRISMA guidelines to evaluate the efficacy and safety of ruxolitinib cream for the treatment of vitiligo. A comprehensive search of PubMed, Google Scholar, and Cochrane Library databases for randomized controlled trials (RCTs). Data selection, screening, extraction, and risk of bias assessment were meticulously performed. Statistical analysis was conducted using Review Manager Software, version 5.4, with significant heterogeneity addressed through appropriate methods. Our meta-analysis included 3 studies with 830 vitiligo patients. Significant improvements were observed in F-VASI, T-VASI, F-BSA, and T-BSA scores, with greater efficacy at 24weeks compared to 12weeks [MD -24.17, 95% CI (-31.78 to -16.56), P < 0.00001], [MD -14.12, 95% CI (-20.54 to -7.70); P < 0.0000], [MD -16.25, 95% CI (-22.20 to -10.31), P < 0.00001], [MD -9.19, 95% CI (-13.47 to -4.92); P < 0.00001]. Ruxolitinib showed increased risk ratios for F-VASI75, F-VASI90, and F-VASI50, indicating better outcomes with longer treatment durations [MD 2.9, 95% CI 1.88-4.49; P < 0.00001], [MD 4.66, 95% CI 2.09-10.39; P = 0.0002], [MD 2.53, 95% CI 1.84-3.46; P < 0.00001]. No significant differences were found in mild and moderate adverse events, while severe cases favored ruxolitinib. Placebo had a significant advantage in any adverse events, with no significant difference in drug-related adverse events. Serious adverse events did not significantly differ between groups. The findings strongly support the efficacy of ruxolitinib therapy in improving various parameters over time for treating vitiligo. However, thorough consideration of its safety profile, particularly concerning adverse events and potential side effects, is warranted. Further studies with larger sample sizes are needed to confirm these conclusions.

Micelle Enabled Buchwald‐Hartwig Amination in Water with the Bening by Design Surfactant TPGS‐750‐M for the Synthesis of the JAK Inhibitor 4‐((2‐Chlorophenyl)amino)‐6‐((6‐methylpyridin‐2‐yl)amino)nicotinamide

AbstractAn efficient and scalable Buchwald‐Hartwig amination towards the synthesis of the API candidate 4‐((2‐Chlorophenyl)amino)‐6‐((6‐methylpyridin‐2‐yl)amino)nicotinamide as a JAK inhibitor was described. The process was developed using water and a water‐miscible co‐solvent. It was facilitated by the benign by design surfactant TPGS‐750‐M, that promoted the robust and reliable preparation of our target compound in high yields, with improved reaction profile and via an operationally simple protocol.

Botulinum toxin type A inhibits the formation of hypertrophic scar through the JAK2/STAT3 pathway.

Hypertrophic scar (HS) is a fibrous proliferative disorder that occurs in the dermis after skin injury. Studies have confirmed that Botulinum toxin type A (BTA) is effective in scar prevention and treatment. However, the specific mechanism remains uncertain. Hypertrophic scar fibroblasts (HSFs) and normal skin fibroblasts (NSFs) from the skin tissues of HS patients were isolated and cultured. Western blot analysis was conducted to measure the expression of JAK2/STAT3 pathway-related proteins. HSFs were treated with the JAK2 inhibitor (AG490) or agonist (C-A1). The CCK-8 assay, EdU staining, scratch-wound assay and transwell assay were used to examine the biological properties of HSFs. Western blot, immunofluorescence, and Sirius red staining were used to assess the fibrosis of HSFs. Additionally, a mouse full-thickness wound model was constructed to investigate the role of BTA in wound healing. The results showed that the JAK2 and STAT3 phosphorylation levels were markedly increased in HS tissues and HSFs. AG490 treatment reduced cell viability, proliferation and migration capacity, and inhibited the fibrosis of HSFs, whereas C-A1 treatment had the opposite effect. BTA treatment inhibited the JAK2/STAT3 pathway. BTA reduced cell viability, proliferation and migration ability, and inhibited the fibrosis of HSFs, while C-A1 intervention weakened the impact of BTA. Meanwhile, BTA promoted wound healing and reduced collagen deposition in vivo. In conclusion, BTA inhibited the JAK2/STAT3 pathway, which in turn hindered the proliferation, migration and fibrosis of HSFs, and promoted wound healing in mice.

Molecular basis for JAK2 inhibition with type II compounds.

176 Background: Upon prolonged exposure, the therapeutic efficiency of current clinical JAK2 inhibitors (type I inhibitors) can be attenuated, leading to drug resistance both in vitro and in vivo through non-genetic mechanisms. In contrast, type II inhibitors stabilize the inactive conformation of the kinase domain preventing the heterodimerization-mediated JAK2 activation. This confers efficacy to type I inhibitor persistent cells, improved efficacy against myeloproliferative neoplasms and other cancers such as B-cell acute lymphoblastic leukemia. Despite the advantages of type II JAK inhibitors, the discovery of type II inhibitor resistance mutation, L884P, in the kinase domain has hampered the further development of JAK2-targeted type II therapeutics. Methods: Here we use combination of protein-inhibitor binding assays, cell-based assays, X-ray crystallography, and computational tools to elucidate the resistance mechanism of JAK2-L884P mutation, to facilitate the development of type II inhibitors with activity against both wild-type and L884P mutated JAK2. Results: We have determined an atomic resolution crystal structure of JAK2-L884P mutant, revealing that mutation induces local changes in the structure but not in the ATP pocket. Furthermore, we have identified several type II compounds inhibiting. Interestingly, they show no major differences in potency in vitro against wild-type of L884P mutated JAK2. Selected compounds profiled in cell lines carrying wild-type or L884P-mutated JAK2, show differences in their cell viability, indicating that a resistance arises via allosteric effects. Conclusions: L884P mutation impacts the inhibitory potency of type II inhibitors via allosteric mechanism.Crystallographic analysis of our type II shortlisted compounds revealed that they differ in their binding modes and suggests that L884P-insensitive drugs can be developed. Preliminary cell-based experiments results confirm these findings. We will now focus on validating these observations with biomolecular simulations to clarify the molecular basis for the inhibitor resistance via L884P mutation. Our studies will facilitate the development of novel type II drugs against JAK2 in myeloproliferative neoplasms.

Preventing periprosthetic osteolysis in aging populations through lymphatic activation and stem cell-associated secretory phenotype inhibition

With increases in life expectancy, the number of patients requiring joint replacement therapy and experiencing periprosthetic osteolysis, the most common complication leading to implant failure, is growing or underestimated. In this study, we found that osteolysis progression and osteoclast differentiation in the surface of the skull bone of adult mice were accompanied by significant expansion of lymphatic vessels within bones. Using recombinant VEGF-C protein to activate VEGFR3 and promote proliferation of lymphatic vessels in bone, we counteracted excessive differentiation of osteoclasts and osteolysis caused by titanium alloy particles or inflammatory cytokines LPS/TNF-α. However, this effect was not observed in aged mice because adipogenically differentiated mesenchymal stem cells (MSCs) inhibited the response of lymphatic endothelial cells to agonist proteins. The addition of the JAK inhibitor ruxolitinib restored the response of lymphatic vessels to external stimuli in aged mice to protect against osteolysis progression. These findings suggest that inhibiting SASP secretion by adipogenically differentiated MSCs while activating lymphatic vessels in bone offers a new method to prevent periprosthetic osteolysis during joint replacement follow-up.