SADS-CoV nsp1 inhibits the STAT1 phosphorylation by promoting K11/K48-linked polyubiquitination of JAK1 and blocks the STAT1 acetylation by degrading CBP.

The newly discovered zoonotic coronavirus swine acute diarrhea syndrome coronavirus (SADS-CoV) causes acute diarrhea, vomiting, dehydration, and high mortality rates in newborn piglets. Although SADS-CoV uses different strategies to evade the host's innate immune system, the specific mechanism(s) by which it blocks the interferon (IFN) response remains unidentified. In this study, the potential of SADS-CoV nonstructural proteins (nsp) to inhibit the IFN response was detected. The results determined that nsp1 was a potent antagonist of IFN response. SADS-CoV nsp1 efficiently inhibited signal transducer and activator of transcription 1 (STAT1) phosphorylation by inducing Janus kinase 1 (JAK1) degradation. Subsequent research revealed that nsp1 induced JAK1 polyubiquitination through K11 and K48 linkages, leading to JAK1 degradation via the ubiquitin-proteasome pathway. Furthermore, SADS-CoV nsp1 induced CREB-binding protein degradation to inhibit IFN-stimulated gene production and STAT1 acetylation, thereby inhibiting STAT1 dephosphorylation and blocking STAT1 transport out of the nucleus to receive antiviral signaling. In summary, the results revealed the novel mechanisms by which SADS-CoV nsp1 blocks the JAK-STAT signaling pathway via the ubiquitin-proteasome pathway. This study yielded valuable findings on the specific mechanism of coronavirus nsp1 in inhibiting the JAK-STAT signaling pathway and the strategies of SADS-CoV in evading the host's innate immune system.

Improvements in immune/melanocyte biomarkers with JAK3/TEC family kinase inhibitor ritlecitinib in vitiligo.

BACKGROUND: Vitiligo is an autoimmune depigmenting disorder with no effective and safe treatments. Its pathogenesis is not fully elucidated. OBJECTIVE: This substudy of a randomized, double-blind, placebo-controlled phase 2b trial (NCT03715829) evaluated effects of ritlecitinib, an oral JAK3/TEC family kinase inhibitor, on skin and blood biomarkers in participants with nonsegmental vitiligo (NSV). METHODS: Sixty-five adults with NSV participated in the substudy and received daily treatment for 24 weeks with placebo (n = 14) or ritlecitinib with or without a 4-week loading dose: 200 (loading dose)/50 mg (n = 13), 100/50 mg (n = 12), 50 mg (n = 11), 30 mg (n = 8), or 10 mg (n = 6). Skin (lesional and nonlesional) biopsy samples were obtained at baseline and at 4 and 24 weeks. Changes from baseline to weeks 4 and 24 in skin and blood molecular and cellular biomarkers were evaluated by RNA sequencing, quantitative real-time PCR, proteomic analysis, and flow cytometry. RESULTS: Ritlecitinib-treated groups showed downregulation of immune biomarkers and upregulation of melanocyte-related markers at weeks 4 and 24 compared to baseline and/or placebo. Significant reductions were seen in CD3+/CD8+ T-cell infiltrates, with significant increases in melanocyte markers (tyrosinase; Melan-A) in NSV lesions in the 50 mg ritlecitinib groups (both P < .05). There was significant, dose-dependent downregulation in T-cell activation, NK, cytotoxic, and regulatory markers in lesional skin (IL-2, IL2-RA, IL-15, CCR7, CD5, CRTAM, NCR1, XCL1, KIR3DL1, FASLG, KLRD; P < .05). TH1 and TH2 markers were also downregulated in lesional skin and blood in a dose-dependent manner (P < .05). Changes in immune biomarkers correlated with clinical response. CONCLUSIONS: Ritlecitinib significantly downregulated proinflammatory biomarkers and increased melanocyte products in skin and blood of participants with NSV, suggesting its potential in treatment. Ritlecitinib-mediated changes positively correlated with clinical response.

CBL family E3 ubiquitin ligases control JAK2 ubiquitination and stability in hematopoietic stem cells and myeloid malignancies.

Janus kinase 2 (JAK2) is a central kinase in hematopoietic stem/progenitor cells (HSPCs), and its uncontrolled activation is a prominent oncogenic driver of hematopoietic neoplasms. However, molecular mechanisms underlying the regulation of JAK2 have remained elusive. Here we report that the Casitas B-cell lymphoma (CBL) family E3 ubiquitin ligases down-regulate JAK2 stability and signaling via the adaptor protein LNK/SH2B3. We demonstrated that depletion of CBL/CBL-B or LNK abrogated JAK2 ubiquitination, extended JAK2 half-life, and enhanced JAK2 signaling and cell growth in human cell lines as well as primary murine HSPCs. Built on these findings, we showed that JAK inhibitor (JAKi) significantly reduced aberrant HSPCs and mitigated leukemia development in a mouse model of aggressive myeloid leukemia driven by loss of Cbl and Cbl-b Importantly, primary human CBL mutated (CBLmut ) leukemias exhibited increased JAK2 protein levels and signaling and were hypersensitive to JAKi. Loss-of-function mutations in CBL E3 ubiquitin ligases are found in a wide range of myeloid malignancies, which are diseases without effective treatment options. Hence, our studies reveal a novel signaling axis that regulates JAK2 in normal and malignant HSPCs and suggest new therapeutic strategies for treating CBLmut myeloid malignancies.

Palmitoylation-dependent control of JAK1 kinase signaling governs responses to neuropoietic cytokines and survival in DRG neurons.

Janus Kinase-1 (JAK1) plays key roles during neurodevelopment and following neuronal injury, while activatory JAK1 mutations are linked to leukemia. In mice, Jak1 genetic deletion results in perinatal lethality, suggesting non-redundant roles and/or regulation of JAK1 for which other JAKs cannot compensate. Proteomic studies reveal that JAK1 is more likely palmitoylated compared to other JAKs, implicating palmitoylation as a possible JAK1-specific regulatory mechanism. However, the importance of palmitoylation for JAK1 signaling has not been addressed. Here, we report that JAK1 is palmitoylated in transfected HEK293T cells and endogenously in cultured Dorsal Root Ganglion (DRG) neurons. We further use comprehensive screening in transfected non-neuronal cells and shRNA-mediated knockdown in DRG neurons to identify the related enzymes ZDHHC3 and ZDHHC7 as dominant protein acyltransferases (PATs) for JAK1. Surprisingly, we found palmitoylation minimally affects JAK1 localization in neurons, but is critical for JAK1's kinase activity in cells and even in vitro. We propose this requirement is likely because palmitoylation facilitates transphosphorylation of key sites in JAK1's activation loop, a possibility consistent with structural models of JAK1. Importantly, we demonstrate a leukemia-associated JAK1 mutation overrides the palmitoylation-dependence of JAK1 activity, potentially explaining why this mutation is oncogenic. Finally, we show that JAK1 palmitoylation is important for neuropoietic cytokine-dependent signaling and neuronal survival and that combined Zdhhc3/7 loss phenocopies loss of palmitoyl-JAK1. These findings provide new insights into the control of JAK signaling in both physiological and pathological contexts.

A gastrointestinal locally activating Janus kinase inhibitor to treat ulcerative colitis.

In this study, we integrated machine learning (ML), structure-tissue selectivity-activity-relationship (STAR), and wet lab synthesis/testing to design a gastrointestinal (GI) locally activating JAK inhibitor for ulcerative colitis treatment. The JAK inhibitor achieves site-specific efficacy through high local GI tissue selectivity while minimizing the requirement for JAK isoform specificity to reduce systemic toxicity. We used the ML model (CoGT) to classify whether the designed compounds were inhibitors or noninhibitors. Then we used the regression ML model (MTATFP) to predict their IC50 against related JAK isoforms of predicted JAK inhibitors. The ML model predicted MMT3-72, which was retained in the GI tract, to be a weak JAK1 inhibitor, while MMT3-72-M2, which accumulated in only GI tissues, was predicted to be an inhibitor of JAK1/2 and TYK2. ML docking methods were applied to simulate their docking poses in JAK isoforms. Application of these ML models enabled us to limit our synthetic efforts to MMT3-72 and MMT3-72-M2 for subsequent wet lab testing. The kinase assay confirmed MMT3-72 weakly inhibited JAK1, and MMT3-72-M2 inhibited JAK1/2 and TYK2. We found that MMT3-72 accumulated in the GI lumen, but not in GI tissue or plasma, but released MMT3-72-M2 accumulated in colon tissue with minimal exposure in the plasma. MMT3-72 achieved superior efficacy and reduced p-STAT3 in DSS-induced colitis. Overall, the integration of ML, the structure-tissue selectivity-activity-relationship system, and wet lab synthesis/testing could minimize the effort in the optimization of a JAK inhibitor to treat colitis. This site-specific inhibitor reduces systemic toxicity by minimizing the need for JAK isoform specificity.

Involvement of Janus kinase-dependent Bcl-xL overexpression in steroid resistance of group 2 innate lymphoid cells in asthma.

The mechanisms underlying the development of steroid resistance in asthma remain unclear. To establish whether as well as the mechanisms by which the activation of Janus kinases (JAKs) is involved in the development of steroid resistance in asthma, murine steroid-resistant models of the proliferation of group 2 innate lymphoid cells (ILC2s) in vitro and asthmatic airway inflammation in vivo were analysed. ILC2s in the lungs of BALB/c mice were sorted and then incubated with IL-33, thymic stromal lymphopoietin (TSLP), and/or IL-7 with or without dexamethasone (10 nM), the pan-JAK inhibitor, delgocitinib (1-10 000 nM), and/or the Bcl-xL inhibitor, navitoclax (1-100 nM), followed by the detection of viable and apoptotic cells. The anti-apoptotic factor, Bcl-xL was detected in ILC2s by flow cytometry. As a steroid-resistant asthma model, ovalbumin (OVA)-sensitized BALB/c mice were intratracheally challenged with OVA at a high dose of 500 µg four times. Dexamethasone (1 mg/kg, i.p.), delgocitinib (3-30 mg/kg, p.o.), or navitoclax (30 mg/kg, p.o.) was administered during the challenges. Cellular infiltration into the lungs was analysed by flow cytometry. Airway remodelling was histologically evaluated. The following results were obtained. (1) Cell proliferation concomitant with a decrease in apoptotic cells was induced when ILC2s were cultured with TSLP and/or IL-7, and was potently inhibited by dexamethasone. In contrast, when the culture with TSLP and IL-7 was performed in the presence of IL-33, the proliferative response exhibited steroid resistance. Steroid-resistant ILC2 proliferation was suppressed by delgocitinib in a concentration-dependent manner. (2) The culture with IL-33, TSLP, and IL-7 induced the overexpression of Bcl-xL, which was clearly inhibited by delgocitinib, but not by dexamethasone. When ILC2s were treated with navitoclax, insensitivity to dexamethasone was significantly cancelled. (3) The development of airway remodelling and the infiltration of ILC2s into the lungs in the asthma model were not suppressed by dexamethasone, but were dose-dependently inhibited by delgocitinib. Combination treatment with dexamethasone and either delgocitinib or navitoclax synergistically suppressed these responses. Therefore, JAKs appear to play significant roles in the induction of steroid resistance by up-regulating Bcl-xL in ILC2s. The inhibition of JAKs and Bcl-xL has potential as pharmacotherapy for steroid-resistant asthma, particularly that mediated by ILC2s.

A panel of janus kinase inhibitors identified with anti-inflammatory effects protect mice from lethal influenza virus infection.

Influenza remains a significant threat to public health. In severe cases, excessive inflammation can lead to severe pneumonia or acute respiratory distress syndrome, contributing to patient morbidity and mortality. While antivirals can be effective if administered early, current anti-inflammatory drugs have limited success in treating severe cases. Therefore, discovering new anti-inflammatory agents to inhibit influenza-related inflammatory diseases is crucial. Herein, we screened a drug library with known targets using a human monocyte U937 infected with the influenza virus to identify novel anti-inflammatory agents. We also evaluated the anti-inflammatory effects of the hit compounds in an influenza mouse model. Our research revealed that JAK inhibitors exhibited a higher hit rate and more potent inhibition effect than inhibitors targeting other drug targets in vitro. Of the 22 JAK inhibitors tested, 15 exhibited robust anti-inflammatory activity against influenza virus infection in vitro. Subsequently, we evaluated the efficacy of 10 JAK inhibitors using an influenza mouse model and observed that seven provided protection ranging from 40% to 70% against lethal influenza virus infection. We selected oclacitinib as a representative compound for an extensive study to further investigate the in vivo therapeutic potential of JAK inhibitors for severe influenza-associated inflammation. Our results revealed that oclacitinib effectively suppressed neutrophil and macrophage infiltration, reduced pro-inflammatory cytokine production, and ultimately mitigated lung injury in mice infected with lethal influenza virus without impacting viral titer. These findings suggest that JAK inhibitors can modulate immune responses to influenza virus infection and may serve as potential treatments for influenza.IMPORTANCEAntivirals exhibit limited efficacy in treating severe influenza when not administered promptly during the infection. Current steroidal and nonsteroidal anti-inflammatory drugs demonstrate restricted effectiveness against severe influenza or are associated with significant side effects. Therefore, there is an urgent need for novel anti-inflammatory agents that possess high potency and minimal adverse reactions. In this study, 15 JAK inhibitors were identified through a screening process based on their anti-inflammatory activity against influenza virus infection in vitro. Remarkably, 7 of the 10 selected inhibitors exhibited protective effects against lethal influenza virus infection in mice, thereby highlighting the potential therapeutic value of JAK inhibitors for treating influenza.

Cyclooxygenase-2/prostaglandin E2 pathway regulates infectious bronchitis virus replication in avian macrophages.

Infectious bronchitis virus (IBV) is a significant respiratory pathogen that affects chickens worldwide. As an avian coronavirus, IBV leads to productive infection in chicken macrophages. However, the effects of IBV infection in macrophages on cyclooxygenase-2 (COX-2) expression are still to be elucidated. Therefore, we investigated the role of IBV infection on the production of COX-2, an enzyme involved in the synthesis of prostaglandin E2 (PGE2) in chicken macrophages. The chicken macrophage cells were infected with two IBV strains, and the cells and culture supernatants were harvested at predetermined time points to measure intracellular and extracellular IBV infection. IBV infection was quantified as has been the COX-2 and PGE2 productions. We found that IBV infection enhances COX-2 production at both mRNA and protein levels in chicken macrophages. When a selective COX-2 antagonist was used to reduce the COX-2 expression in macrophages, we observed that IBV replication decreased. When IBV-infected macrophages were treated with PGE2 receptor (EP2 and EP4) inhibitors, IBV replication was reduced. Upon utilizing a selective COX-2 antagonist to diminish PGE2 expression in macrophages, a discernible decrease in IBV replication was observed. Treatment of IBV-infected macrophages with a PGE2 receptor (EP2) inhibitor resulted in a reduction in IBV replication, whereas the introduction of exogenous PGE2 heightened viral replication. Additionally, pretreatment with a Janus-kinase two antagonist attenuated the inhibitory effect of recombinant chicken interferon (IFN)-γ on viral replication. The evaluation of immune mediators, such as inducible nitric oxide (NO) synthase (iNOS), NO, and interleukin (IL)-6, revealed enhanced expression following IBV infection of macrophages. In response to the inhibition of COX-2 and PGE2 receptors, we observed a reduction in the expressions of iNOS and IL-6 in macrophages, correlating with reduced IBV infection. Overall, IBV infection increased COX-2 and PGE2 production in addition to iNOS, NO, and IL-6 expression in chicken macrophages in a time-dependent manner. Inhibition of the COX-2/PGE2 pathway may lead to increased macrophage defence mechanisms against IBV infection, resulting in a reduction in viral replication and iNOS and IL-6 expressions. Understanding the molecular mechanisms underlying these processes may shed light on potential antiviral targets for controlling IBV infection.

Omenn Syndrome in Two Infants with Different Hypomorphic Variants in Janus Kinase 3.

Biallelic null or hypomorphic variants in JAK3 cause SCID and less frequently Omenn syndrome. We investigated homozygous hypomorphic JAK3 mutations in two patients, and expression and function of a novel JAK3R431P variant in Omenn syndrome. Immunophenotyping of PBMC from the patient with the novel JAK3R431P variant was undertaken, by flow cytometry and Phosflow after stimulation with IL-2, IL-7, and IL-15. JAK3 expression was investigated by Western blotting. We report two patients with homozygous hypomorphic JAK3 variants and clinical features of Omenn syndrome. One patient had a previously described JAK3R775H variant, and the second had a novel JAK3R431P variant. One patient with a novel JAK3R431P variant had normal expression of JAK3 in immortalised EBV-LCL cells but reduced phosphorylation of STAT5 after stimulation with IL-2, IL-7, and IL-15 consistent with impaired kinase activity. These results suggest the JAK3R431P variant to be hypomorphic. Both patients are alive and well after allogeneic haematopoietic stem cell transplantation. They have full donor chimerism, restitution of thymopoiesis and development of appropriate antibody responses following vaccination. We expand the phenotype of hypomorphic JAK3 deficiency and demonstrate the importance of functional testing of novel variants in disease-causing genes.

Effects of upadacitinib on enthesitis in patients with psoriatic arthritis: a post hoc analysis of SELECT-PsA 1 and 2.

OBJECTIVES: To characterize the effect of upadacitinib 15 mg once daily (UPA15) on enthesitis in patients with psoriatic arthritis from the SELECT-PsA Phase 3 trials. METHODS: Patients with an inadequate response/intolerance to ≥ 1 non-biologic DMARD (SELECT-PsA 1) or ≥ 1 biologic DMARD (SELECT-PsA 2) received UPA15, adalimumab 40 mg every other week or placebo (weeks 0-24) switched to UPA15 (week 24 onward). The Leeds Enthesitis Index (LEI) and Spondyloarthritis Research Consortium of Canada (SPARCC) index were used to assess improvement in enthesitis, enthesitis resolution, maintenance of enthesitis resolution, and protection from enthesitis development through week 56. RESULTS: Data from 639 patients receiving UPA15 and 635 patients receiving placebo (including 317 patients who switched from placebo to UPA15) were analysed. UPA15 led to higher rates of enthesitis resolution vs placebo at week 24 (LEI: 59.8% vs 38.0%; SPARCC index: 50.6% vs 31.5%, respectively) and greater improvements in the LEI (-1.7 vs -1.0) and SPARCC index (-3.4 vs -1.9); improvements were maintained through week 56. Improvements were observed after 12 weeks of UPA15 treatment. Over 90% of patients without enthesitis (LEI = 0) at baseline receiving UPA15 were enthesitis-free at week 56, and UPA15 prevented recurrence of enthesitis at week 56 in > 80% of patients with enthesitis at baseline who achieved resolution (LEI = 0) at week 24. CONCLUSIONS: UPA15 is associated with a comprehensive improvement in enthesitis, with improvements observed after 12 weeks of treatment. Additionally, treatment with UPA15 was associated with maintaining an enthesitis-free state after resolution and protection against new-onset enthesitis. CLINICALTRIALS.GOV IDENTIFIERS: NCT03104400 (SELECT-PsA 1) and NCT03104374 (SELECT-PsA 2).

Cancer risk in patients with rheumatoid arthritis treated with janus kinase inhibitors: a nationwide Danish register-based cohort study.

OBJECTIVES: We aimed to investigate the risk of first primary cancer in patients with RA treated with janus kinase inhibitors (JAKi) compared with those who received biologic DMARDs (bDMARDs) in a real-world setting. METHODS: We performed an observational cohort study using the nationwide registers in Denmark. Patients with RA aged 18+ years, without a previous cancer diagnosis, and who initiated treatment with JAKi or bDMARDs from 1 January 2017 to 31 December 2020 were followed for any cancer (except non-melanoma skin cancer). We applied inverse probability of treatment weighting (IPTW) to account for covariate differences between treatment groups. IPTW-generated weights were used with cause-specific Cox (CSC) models to calculate hazard ratios (HRs) for cancer incidence in JAKi-treated compared with bDMARD-treated patients with RA. RESULTS: We identified 875 and 4247 RA patients treated with JAKi and bDMARDs, respectively. The JAKi group contributed 1315 person years (PYRS) and 19 cancers, the bDMARD group contributed 8597 PYRS and 111 cancers, with corresponding crude incidence rates per 1000 PYRS of 14.4 and 12.9. Comparing the two groups using weighted CSC models, a HR of 1.41 (95% CI 0.76, 2.37, 95% CIs) was seen for JAKi- vs bDMARD-treated patients with RA. CONCLUSION: JAKi treatment in real-world patients with RA was not associated with a statistically significant increased risk of first primary cancer compared with those who received bDMARDs. However, several numerically increased risk estimates were detected, and a clinically important excess risk of cancer among JAKi recipients cannot be dismissed.

Predictive factors and treatment outcomes associated with difficult-to-treat rheumatoid arthritis conditions: the ANSWER cohort study.

OBJECTIVES: To investigate the predictive factors for difficult-to-treat rheumatoid arthritis (D2T RA) and assess the efficacy of biological disease-modifying antirheumatic drugs (bDMARDs) and Janus kinase inhibitors (JAKi). METHODS: Retrospective analysis was conducted on data from the ANSWER cohort comprising 3,623 RA patients treated with bDMARDs or JAKi in Japan. Multivariate Cox proportional hazards modelling was used to analyse the hazard ratios (HRs) for treatment retention. RESULTS: Of these, 450 (12.4%) met the first two criteria of EULAR D2T RA definition (defined as D2T RA in this study). Factors contributing to D2T RA included age over 75 (compared to those under 65, HR = 0.46, 95% CI: 0.31 to 0.69), higher rheumatoid factor (RF) titres (HR = 1.005, 95% CI: 1.00 to 1.01), higher clinical disease activity index (HR = 1.02, 95% CI: 1.01 to 1.03), lower methotrexate dosage (HR = 0.97, 95% CI: 0.95 to 0.99), and comorbidities like hypertension (HR = 1.53, 95% CI: 1.2 to 1.95) and diabetes (HR = 1.37, 95% CI: 1.09 to 1.73). Anti-interleukin 6 receptor antibodies (aIL-6R, HR = 0.53, 95% CI: 0.37 to 0.75) and JAKi (HR = 0.64, 95% CI: 0.46 to 0.90) were associated with fewer discontinuations due to ineffectiveness compared to tumour necrosis factor inhibitors. Oral glucocorticoids usage (HR = 1.65, 95% CI: 1.11 to 2.47) was linked to increased discontinuation due to toxic adverse events. CONCLUSION: Younger onset, higher RF titres, and comorbidities predicted D2T RA development. For managing D2T RA, aIL-6R and JAKi exhibited superior drug retention.

IL-6 inhibitors and JAK inhibitors as favourable treatment options for patients with anaemia and rheumatoid arthritis: ANSWER cohort study.

OBJECTIVES: Anaemia, a common comorbidity of RA, is related to high disease activity and poor prognosis. It is unknown which biologic/targeted synthetic (b/ts)-DMARDs are optimal for patients with anaemia and RA in regulating anaemia and controlling disease activity. METHODS: We investigated the change in haemoglobin (Hb) levels, drug retention rates and disease activities after the administration of b/ts-DMARDs with different modes of action [TNF inhibitors (TNFis), immunoglobulin fused with cytotoxic T-lymphocyte antigen (CTLA-4-Ig), IL-6 receptor inhibitors (IL-6Ris) and Janus kinase inhibitors (JAKis)] in patients with RA stratified by baseline Hb levels using the multicentre observational registry for patients with RA in Japan (ANSWER cohort). RESULTS: A total of 2093 patients with RA were classified into three groups based on tertiles of the baseline Hb levels (Hblow, anaemic; Hbint, intermediate; Hbhigh, non-anaemic). IL-6Ri increased Hb levels in all groups (the mean change at 12 months in Hblow was +1.5 g/dl, Hbint +0.7 g/dl and Hbhigh +0.1 g/dl). JAKis increased the Hb level in patients with anaemia and RA and retained or decreased the Hb level in non-anaemic patients (the mean change at 12 months in Hblow was +0.6 g/dl, Hbint 0 g/dl and Hbhigh -0.3 g/dl). In patients with anaemia and RA, overall adjusted 3-year drug retention rates were higher in JAKi followed by IL-6Ri, CTLA4-Ig and TNFi (78.6%, 67.9%, 61.8% and 50.8%, respectively). Change of disease activity at 12 months was not different among different b/ts-DMARDs treatments. CONCLUSION: IL-6Ri and JAKi can effectively treat patients with anaemia and RA in a real-world setting.

TYK2 inhibition with deucravacitinib ameliorates erosive oral lichen planus.

Erosive oral lichen planus (OLP) is a challenging disease. This T cell driven disorder frequently shows a treatment unresponsive course and strongly limits patients' quality of life. The disease lacks FDA or EMA approved drugs for its treatment and the efficacy of the commonly administered treatments (i.e. topical and systemic steroids, steroid sparing agents) is often only partial. Although the etiopathogenesis of the disease still needs to be fully elucidated, recent advances helped to identify interferon-É£ (IFN-É£) as a pivotal cytokine in OLP pathogenesis, thus making the interference with its signalling a therapeutic target. Janus kinase (JAK) inhibitors therefore gained relevance for their inhibitory effect on IFN-É£ signalling. While some drugs such as abrocitinib, upadacitinib, tofacitinib directly interfere with IFN-É£ signalling through blockade of JAK1 and/or JAK2, deucravacitinib, a selective TYK-2 inhibitor indirectly interferes on IFN-É£ activation through interference with interleukin (IL)-12, a potent promotor for Th1/IFN-É£ responses. This mechanism of action makes deucravacitinib a candidate drug for the treatment of OLP. Here we provide initial evidence that deucravacitinib 6 mg daily has a beneficial effect in three patients with oral OLP.

TREX-1 related Aicardi-Goutières syndrome improved by Janus kinase inhibitor.

Aicardi-Goutières syndrome (AGS) is a genetic interferonopathy classically characterized by early onset of severe neurologic injury with basal ganglia calcifications, white matter abnormalities, and progressive cerebral atrophy, along with lymphocytosis and raised interferon alpha (INFα) in the cerebrospinal fluid (CSF). Here, we report a 31/2 year-old patient born with prenatal onset AGS, first manifesting as intra-uterine growth retardation. Cranial ultrasonography and cerebral MRI revealed ventriculomegaly and periventricular and basal ganglia calcifications, along with cerebral atrophy. Perinatal infections and known metabolic disorders were excluded. Both CSF lymphocytosis and raised INFα were present. Molecular analysis disclosed two already described compound heterozygous pathogenic variants in TREX1 (c. 309dup, p.(Thr104Hisfs*53) and c. 506G > A, p.(Arg169His)). The evolution was marked by severe global developmental delay with progressive microcephaly. Promptly, the patient developed irritability, quadri-paretic dyskinetic movements, and subsequently tonic seizures. Sensorineural hearing loss was detected as well as glaucoma. Initially, he was symptomatically treated with trihexyphenidyl followed by levetiracetam and topiramate. At age 22 months, baricitinib (0.4 mg/kg/day) was introduced, leading to normal serum INFα levels. Clinically, dyskinetic movements significantly decreased as well as irritability and sleep disturbance. We confirmed that baricitinib was a useful treatment with no major side effect.

Association of JAK2V617F allele burden and clinical correlates in polycythemia vera: a systematic review and meta-analysis.

Janus kinase 2 (JAK2) V617F mutation is present in most patients with polycythemia vera (PV). One persistently puzzling aspect unresolved is the association between JAK2V617F allele burden (also known as variant allele frequency) and the relevant clinical characteristics. Numerous studies have reported associations between allele burden and both hematologic and clinical features. While there are strong indications linking high allele burden in PV patients with symptoms and clinical characteristics, not all associations are definitive, and disparate and contradictory findings have been reported. Hence, this study aimed to synthesize existing data from the literature to better understand the association between JAK2V617F allele burden and relevant clinical correlates. Out of the 1,851 studies identified, 39 studies provided evidence related to the association between JAK2V617F allele burden and clinical correlates, and 21 studies were included in meta-analyses. Meta-analyses of correlation demonstrated that leucocyte and erythrocyte counts were significantly and positively correlated with JAK2V617F allele burden, whereas platelet count was not. Meta-analyses of standardized mean difference demonstrated that leucocyte and hematocrit were significantly higher in patients with higher JAK2V617F allele burden, whereas platelet count was significantly lower. Meta-analyses of odds ratio demonstrated that patients who had higher JAK2V617F allele burden had a significantly greater odds ratio for developing pruritus, splenomegaly, thrombosis, myelofibrosis, and acute myeloid leukemia. Our study integrates data from approximately 5,462 patients, contributing insights into the association between JAK2V617F allele burden and various hematological parameters, symptomatic manifestations, and complications. However, varied methods of data presentation and statistical analyses prevented the execution of high-quality meta-analyses.

Identification and validation of the association of Janus kinase 2 mutations with the response to immune checkpoint inhibitor therapy.

BACKGROUND: Janus kinase 2 (JAK2) mutation plays an important role in T cell immunity. However, the effect of JAK2 mutation on immunotherapy is largely uncharacterized. METHODS: In this study, we analyzed the effect of JAK2 mutation on the efficacy and outcomes of immune checkpoint inhibitor (ICI) therapy in the discovery cohort (n = 662) and the verification cohort (n = 1423). Furthermore, we explored the association of JAK2 mutation with the tumor immune microenvironment in a multiomics cohort. RESULTS: In the discovery cohort (n = 662), JAK2 mutant-type patients had a better objective response rate (58.8% vs. 26.7%, P = 0.010), durable clinical benefit (64.7% vs. 38.9%, P = 0.043), progression-free survival (hazard ratio [HR] = 0.431, P = 0.015), and overall survival (HR = 0.378, P = 0.025), relative to JAK2 wild-type patients. Moreover, we further verified the prognostic significance of JAK2 mutation in an independent ICI treatment cohort with a larger sample size (n = 1423). In addition, we discovered that the JAK2 mutation was remarkably related to increased immunogenicity, such as a higher TMB, higher expression of costimulatory molecules and stimulation of antigen processing mechanisms. In addition, JAK2 mutation was positively correlated with activated anticancer immunity, such as infiltration of various immune cells and higher expression of chemokines. CONCLUSION: Our study demonstrates that JAK2 mutation is a novel marker that can be used to effectively predict prognosis and response to ICI therapy.

Keratinocyte Exosomes for Topical Delivery of Tofacitinib in Treatment of Psoriasis: an In Vitro/ In Vivo Study in Animal Model of Psoriasis.

INTRODUCTION: Exosomes are extracellular vesicles in the range of 40-150 nm released from the cell membrane. Exosomes secreted by keratinocytes can communicate with other keratinocytes and immune cells with specific biomarkers at their surface, which may be effective on inflammation of psoriasis and its pathogenesis. OBJECTIVE: The present study aimed to formulate and study effectiveness of an exosomal delivery system of tofacitinib (TFC). METHODS: TFC was loaded by different methods in exosomes and then characterized for particle size, zeta potential, drug loading efficiency, and release efficiency. By comparing these parameters, the probe sonication method was chosen to load TFC into exosomes. The MTT assay was used to compare the cytotoxicity of the free drug with the TFC-loaded exosomes (TFC-Exo), and Real-time PCR was used to determine the expression levels of several genes involved in psoriasis expressed in the A-431 keratinocyte and their suppression after treatment. Animal model of psoriasis was induced in BALB/c mice by imiquimod and the efficacy of free TFC, and TFC-Exo were studies on macroscopic appearance and histopathological symptoms. RESULTS: Exosomes encapsulating TFC showed lower cytotoxicity in MTT assay, higher suppression the expression of TNF-a, IL-23, IL-6, and IL-15 genes in real-time PCR and better therapeutic effect on animal models compered to free TFC. CONCLUSIONS: This method of drug delivery for TFC may be effective on enhancing its therapeutic effects and reduction its side effects favorably in chronic administration.

Meaningful Symptomatic Change in Patients With Myelofibrosis From the SIMPLIFY Studies.

OBJECTIVES: Patients with myelofibrosis develop symptoms due to bone marrow fibrosis, systemic inflammation, and/or organomegaly. Alleviating symptoms improves overall quality of life. Clinical trials have historically defined symptom response as a reduction of at least 50% in Total Symptom Score at week 24 compared with baseline. Whether 50% constitutes a meaningful benefit has not been established. This study determined the meaningful change threshold (MCT) for 2 momelotinib phase III trials, SIMPLIFY-1 and SIMPLIFY-2. METHODS: The absolute and percentage MCT was determined using anchor-based methods applied to the modified Myeloproliferative Neoplasm Symptom Assessment Form v2.0 and Patient Global Impression of Change. MCTs were applied retrospectively to determine responder rates. Generalized estimating equations estimated the treatment-related difference in likelihood of improvement. RESULTS: In SIMPLIFY-1, a Janus kinase inhibitor-naive population, the MCT was 8 points. In SIMPLIFY-2, a previously Janus kinase inhibitor-treated population, the MCT was 6 points. A 32% MCT was determined in both studies, showing that the historic 50% reduction threshold may be a conservative choice. In SIMPLIFY-1, a similar proportion of patients achieved responder status with 24 weeks of momelotinib or ruxolitinib therapy based on the absolute MCT (39% vs 41%, respectively). In SIMPLIFY-2, a significantly greater proportion of patients treated with momelotinib achieved responder states compared with best available therapy based on absolute and percent change MCTs. CONCLUSIONS: This study demonstrates that momelotinib provided clinically meaningful symptom benefit for patients with myelofibrosis and provides insight into the appropriateness of the symptom change threshold used in historical studies.

Deciphering the molecular choreography of Janus kinase 2 inhibition via Gaussian accelerated molecular dynamics simulations: a dynamic odyssey.

The Janus kinases (JAK) are crucial targets in drug development for several diseases. However, accounting for the impact of possible structural rearrangements on the binding of different kinase inhibitors is complicated by the extensive conformational variability of their catalytic kinase domain (KD). The dynamic KD contains mainly four prominent mobile structural motifs: the phosphate-binding loop (P-loop), the αC-helix within the N-lobe, the Asp-Phe-Gly (DFG) motif, and the activation loop (A-loop) within the C-lobe. These distinct structural orientations imply a complex signal transmission path for regulating the A-loop's flexibility and conformational preference for optimal JAK function. Nevertheless, the precise dynamical features of the JAK induced by different types of inhibitors still remain elusive. We performed comparative, microsecond-long, Gaussian accelerated molecular dynamics simulations in triplicate of three phosphorylated JAK2 systems: the KD alone, type-I ATP-competitive inhibitor (CI) bound KD in the catalytically active DFG-in conformation, and the type-II inhibitor (AI) bound KD in the catalytically inactive DFG-out conformation. Our results indicate significant conformational variations observed in the A-loop and αC helix motions upon inhibitor binding. Our studies also reveal that the DFG-out inactive conformation is characterized by the closed A-loop rearrangement, open catalytic cleft of N and C-lobe, the outward movement of the αC helix, and open P-loop states. Moreover, the outward positioning of the αC helix impacts the hallmark salt bridge formation between Lys882 and Glu898 in an inactive conformation. Finally, we compared their ligand binding poses and free energy by the MM/PBSA approach. The free energy calculations suggested that the AI's binding affinity is higher than CI against JAK2 due to an increased favorable contribution from the total non-polar interactions and the involvement of the αC helix. Overall, our study provides the structural and energetic insights crucial for developing more promising type I/II JAK2 inhibitors for treating JAK-related diseases.