Impact of age and cardiovascular risk factors on the incidence of adverse events in patients with rheumatoid arthritis treated with Janus Kinase inhibitors: data from a real-life multicentric cohort.

Inhibiting Janus Kinases (JAK) is a crucial therapeutic strategy in rheumatoid arthritis (RA). However, the use of JAK inhibitors has recently raised serious safety concerns. The study aims to evaluate the safety profile of JAKi in patients with RA and identify potential risk factors (RFs) for adverse events (AEs). Data of RA patients treated with JAKi in three Italian centers from January 2017 to December 2022 were retrospectively analyzed. 182 subjects (F:117, 64.3%) underwent 193 treatment courses. 78.6% had at least one RF, including age ≥ 65 years, obesity, smoking habit, hypertension, dyslipidemia, hyperuricemia, diabetes, previous VTE or cancer, and severe mobility impairment. We identified 70 AEs (28/100 patients/year), among which 15 were serious (6/100 patients/year). A high disease activity was associated with AEs occurrence (p = 0.03 for CDAI at T0 and T6; p = 0.04 for SDAI at T0 and T6; p = 0.01 and p = 0.04 for DAS28ESR at T6 and T12, respectively). No significant differences in AEs occurrence were observed after stratification by JAKi molecules (p = 0.44), age groups (p = 0.08) nor presence of RFs (p > 0.05 for all of them). Neither the presence of any RFs, nor the cumulative number of RFs shown by the patient, nor age ≥ 65 did predict AEs occurrence. Although limited by the small sample size and the limited number of cardiovascular events, our data do not support the correlation between cardiovascular RFs-including age-and a higher incidence of AEs during JAKi therapy. The role of uncontrolled disease activity in AEs occurrence should by emphasized.

The Role of Major Salivary Gland Ultrasound in the Diagnostic Workup of Sicca Syndrome: A Large Single-Centre Study.

(1) Objective: To determine the diagnostic accuracy of major salivary gland ultrasonography (SGUS) in primary Sjogren's syndrome (SS), we used the Outcome Measures in Rheumatology Clinical Trials (OMERACT) scoring system on a large single-centre cohort of patients with sicca syndrome. (2) Method: We retrospectively collected the clinical, imaging and serological data of all the patients referred with a suspicion of SS who underwent SGUS and minor salivary glands biopsy. (3) Results: A total of 132 patients were included. The SGUS scores were correlated between the two sides (p < 0.001). The diagnostic cut-off for SS (AUROC: 0.7408) was 6 for the SGUS-global sum (sensitivity: 32.43%; specificity: 96.84%). The cut-off with the highest specificity for SS diagnosis was 7. In the patients with a final diagnosis of SS, the mean SGUS score was significantly higher (p < 0.001) than that of the non-SS patients (3.73 vs. 1.32 for the SGUS-global sum). A significant correlation was demonstrated between the SGUS scores and final SS diagnosis (p < 0.001), biopsy positivity (p < 0.001), ANA positivity (p = 0.016), Ro-SSA positivity (p = 0.01), and gland fibrosis (p = 0.02). (4) Conclusions: SGUS, using the OMERACT scoring system, has moderate sensitivity and high specificity for the diagnosis of SS. The scoring showed a strong and direct correlation with all the clinical hallmarks of SS diagnosis, such as the positivity of a labial salivary gland biopsy, ANA and Ro-SSA statuses, and salivary gland fibrosis. Because of its high specificity, a SGUS-global score > 6 could be therefore employed for the diagnosis of SS in the case of ANA negativity or the unavailability of a biopsy.

ToRaRI (Tofacitinib in Rheumatoid Arthritis a Real-Life experience in Italy): Effectiveness, safety profile of tofacitinib and concordance between patient-reported outcomes and physician's global assessment of disease activity in a retrospective study in Central-Italy.

INTRODUCTION: The use of Janus Kinase Inhibitors (JAK-Is) in rheumatoid arthritis (RA) has entered in daily practice. In consideration of ORAL-Surveillance trial and the new EULAR recommendations, real-world data are needed to assess Jak-Is safety and effectiveness. The multicenter study presented here aimed to evaluate effectiveness and safety of tofacitinib in a real-life cohort. METHODS: A retrospective analysis was performed from September 2021 to December 2022. Data were collected when tofacitinib was started (T0) and after 3 (T3), 6 (T6) and 12 (T12) months of treatment. The primary objective was to analyze the efficacy and safety of tofacitinib. Safety was assessed by recording adverse events (AEs) with and without discontinuation. The secondary objective was to assess the difference between Patient-Reported Outcomes (PROs) and Physician's Global Assessment of disease activity (PhGA). RESULTS: 122 patients were included in the study from the following rheumatology Centers: Pisa, Ancona, Florence (two Centers), Siena, and Sardinia. A statistically significant improvement in DAS-28-CRP, CDAI and SDAI score was observed at T3, T6, compared to baseline (p < 0.001). Improvement was confirmed in patients who reach T12. Patients naïve to bDMARDs showed a shorter remission time and higher remission rates. There was also a statistically significant improvement in PROs compared to baseline (p < 0.001). The improvement was rapid and was consistent with PhGA. The 12-month retention rate for tofacitinib was 89.35%. Reasons to stop tofacitinib were: insufficient response (7), gastrointestinal symptoms (2), infection (1), malignancy (1), Zoster (1), pruritus sine materia (1). CONCLUSIONS: Tofacitinib is safe and effective in our RA cohort. It induces higher remission rates in patients naive to bDMARDs, suggesting that there may be a benefit using it as first-line therapy. Additionally, improvement in PROs was consistent with PhGA scores, demonstrating how tofacitinib affects both the objective and subjective components of disease activity. Key Points 1. JAK inhibitors are considered at a similar level as biologic agents in terms of effectiveness. 2. After ORAL-Surveillance results, real-world data are needed to assess the benefit/risk profile of Jaki. 3. Disagreement between patients and physicians has been previously reported with biologic therapy among patients with rheumatoid arthritis, with patients rating disease activity higher than physicians. 4. Jak inhibitors could reduce this discrepancy, due to their mechanism of action.

ReLiFiRa (Real Life Filgotinib in Rheumatoid Arthritis): Retrospective Study of Efficacy and Safety in Common Clinical Practice.

BACKGROUND: Filgotinib (FIL) is a selective JAK1 inhibitor with an affinity 30-fold higher than JAK2, approved to treat moderate to severe active rheumatoid arthritis (RA), in adults with inadequate response or intolerance to one or more disease-modifying antirheumatic drugs (DMARDs). METHODS: We conducted a retrospective, multicentric study in order to evaluate efficacy and safety of FIL 200 mg daily therapy, after 3 and 6 months, in 120 patients affected by RA, managed in Tuscany and Umbria rheumatological centers. The following clinical records were analyzed: demographical data, smoking status, previous presence of comorbidities (Herpes zoster -HZ- infection, venous thromboembolism -VTE-, major adverse cardiovascular events -MACE-, cancer, diabetes, and hypertension), disease duration, presence of anti-citrullinated protein antibodies (ACPA), rheumatoid factor (RF), number of biological failures, and prior csDMARDs utilized. At baseline, and after 3 (T3) and 6 (T6) months of FIL therapy, we evaluated mean steroid dosage, csDMARDs intake, clinimetric indexes (DAS28, CDAI, HAQ, patient and doctor PGA, VAS), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), and body mass index (BMI). RESULTS: At baseline, the mean disease duration was 9.4 ± 7.5 years; the prevalence of previous HZ infection, VTE, MACE, and cancer was respectively 4.12%, 0%, 7.21%, and 0.83%, respectively. In total, 76.3% of patients failed one or more biologics (one biological failure, 20.6%; two biological failures, 27.8%; three biological failures, 16.5%; four biological failures, 10.3%; five biological failures, 1.1%). After 3 months of FIL therapy, all clinimetric index results significantly improved from baseline, as well as after 6 months. Also, ESR and CRP significatively decreased at T3 and T6. Two cases of HZ were recorded, while no new MACE, VTE, or cancer were recorded during the observation time. CONCLUSION: Despite the limitations of the retrospective study and of the observational period of only 6 months, real-life data on the treatment of RA patients with FIL demonstrate that this Jak inhibitor therapy is safe in terms of CV, VTE events, and occurrence of cancer, and is also effective in a population identified as "difficult to treat" due to failure of previous b-DMARD therapy.

Diagnostic role of minor salivary glands biopsy in Sjögren's syndrome: correlations between histology and autoimmunity in a large, monocentric cohort.

Introduction: Based on ACR/EULAR classification criteria, minor salivary glands biopsy (MSGB) is a useful diagnostic tool for the diagnosis of primary Sjögren's syndrome (SS). The main objective of our study was to evaluate the diagnostic role of MSGB, as well as to highlight correlations between histological findings and autoimmune profiles. Material and methods: We retrospectively evaluated histological and autoimmunity data from patients who underwent MSGB in our department in cases of suspected SS, from March 2011 to December 2018. Salivary gland samples were evaluated using Chisholm and Mason (CM) grading and the focus score (FS). Results: A total of 1,264 patients (108 males, 1,156 females) were included. The median age was 55.22 ±13.51 years (range: 15-87). In univariate binary logistic regression, CM ≥ 3 and FS ≥ 1 were significantly predicted by antinuclear antibodies (ANA), anti-extractable nuclear antigens (ENA) and anti-Ro/SSA titer as well as anti-La/SSB, anti-Ro/SSA, rheumatoid factor (RF) and anti-citrullinated protein antibodies (ACPA) positivity. In multivariate analysis, CM ≥ 3 and MSGB positivity were significantly associated with ANA titer; FS ≥ 1 was not associated with laboratory findings. A positive biopsy was associated with laboratory findings, as ANA and ENA titers, anti-Ro/SSA, anti-La/SSB, RF and ACPA positivity may discriminate patients with SS-related histological findings. Conclusions: Minor salivary glands biopsy is a useful tool to diagnose SS in cases of highly suggestive clinical symptoms but in the absence of a specific autoimmunity.

Routine IgG4 staining in minor salivary gland biopsy in a cohort of Italian Caucasian patients suffering from xerostomia.

Objectives: IgG4-related disease is a potentially systemic disease mimicking and overlapping with different autoimmune diseases, such as primary Sjögren's syndrome (pSS). The involvement of salivary glands, previously called Mikulicz's disease, has been reclassified as IgG4-related sialadenitis (SA). The aim of this study was to assess the prevalence of IgG4-SA in a cohort of Italian Caucasian patients presenting with xerostomia and to evaluate the eventual overlap between IgG4-SA and pSS. Material and methods: We included 154 patients - 15 males and 139 females, mean age 54.18 ±14.24 years, who underwent minor salivary gland biopsy between March and December 2019 for xerostomia. Histopathology was evaluated using Chisholm-Mason (CM) and focus score (FS) for pSS and immunohistochemical study with IgG4 staining for IgG4-SA were performed. Serum autoantibodies (anti-SSa/RoAb, anti-SSB/LaAb, antinuclear antibodies, rheumatoid factor) were also assessed. Results: In 69 patients (44.8%) FS 0 was found, while FS ≥ 1 was presented in 85 (55.2%). Chisholm-Mason score < 3 and CM ≥ 3 was found in 73 (47.4%) and 81 (52.6%) cases, respectively. IgG4/high-power field level was 20 in 3 pSS patients (1.9%), but none of them had an IgG4/IgG ratio ≥ 40, as well as tissue fibrosis with storiform pattern, obliterative vasculitis, and tissue eosinophilia. The diagnosis of pSS, was confirmed in 92 patients (59.74%). No patient was definitively diagnosed with an IgG4-related disease. Conclusions: In the case of xerostomia, the evaluation of the histopathological specimen for IgG4 should not be routinely performed, at least in an Italian-based Caucasian population. Moreover, immunohistochemistry should not be requested in the case of a negative result of biopsy for pSS.

Inflammatory muscle involvement in systemic vasculitis: A systematic review.

Vasculitis are severe systemic autoimmune diseases which may involve different organs and systems. Conversely, muscles do not represent an organ commonly involved by systemic vasculitis and myositis is not include among any classification or diagnostic criterion of vasculitis. In this regard, we aimed to review the literature in order to report all the available evidence concerning the inflammatory involvement of muscle in patients affected by systemic vasculitis. We collected a total of 108 papers, for a sum of 395 patients affected by muscle vasculitis. Most of them suffered from medium and small vessels vasculitis (mainly polyarteritis nodosa and ANCA-associated vasculitis) or from vasculitis secondary to rheumatoid arthritis. Conversely, muscle involvement in case of large vessel vasculitis occurred seldom, while only few papers reported such occurrence in Kawasaki or Behçet's disease. Histological findings may differ, but the most common ones displayed a necrotizing vasculitis of perimysium vessels, while granulomatous vasculitis was assessed only in case of ANCA-associated vasculitis patients. Creatine kinase were usually within normal range, seldom elevated, while imaging findings were generally undistinguishable from the ones found in idiopathic inflammatory myopathies: magnetic resonance imaging displays signal hyperintensity in T2 and STIR scans, while few data exist for positron emission tomography. The presentation of the disease may be fearsome and severe, sometimes life-threatening, but an overall good response to conventional immunosuppressants and/or glucocorticoids has been reported.

Ultrasound evaluation of the scapholunate ligament and scapholunate joint space in patients with wrist complaints in a rheumatologic setting.

AIM: The aims of the study were to perform an ultrasound assessment of the dorsal portion of the scapholunate interosseous ligament and scapholunate joint space in patients with wrist complaints in a rheumatologic setting, to describe ultrasound abnormalities about scapholunate interosseous ligament region, and to correlate them with clinical data, presence of dorsal ganglion cysts and diagnoses of rheumatic diseases. MATERIAL AND METHODS: Seventy-four consecutive patients with wrist pain and/or swelling were evaluated by routine power Doppler ultrasound. Forty normal wrists were studied to confirm the normality values of the scapholunate joint. RESULTS: The mean width of the normal scapholunate joint was 2.49 mm (±0.49 SD), with a coefficient of variation on repeated measurements of 3.662%. The best predictors of scapholunate interosseous ligament degeneration were: older age (p <0.0001), male gender (p = 0.0049), and radiocarpal effusion (p = 0.0156). The presence of osteophytosis and calcifications of the scapholunate joint were higher (p <0.001) in rheumatic patients. Scapholunate calcifications showed a sensitivity of 98.2% and a specificity of 61.1% for calcium pyrophosphate deposition disease. Dorsal ganglion cysts were more frequent in younger subjects (p <0.0012) without rheumatic conditions (p <0.0001) or midcarpal synovitis (p <0.0001). Larger cysts often exhibited power Doppler signal (p <0.0001). The best predictors of scapholunate dissociation were: male gender (p = 0.0002), presence of midcarpal synovitis (p <0.0137), and higher grade of scapholunate interosseous ligament degeneration (p <0.0001). Scapholunate widening was greater (p = 0.0419) in calcium pyrophosphate deposition disease or rheumatoid arthritis than in other rheumatic conditions. CONCLUSIONS: Ultrasound findings of scapholunate interosseous ligament degeneration and calcification, scapholunate space enlargement, and dorsal ganglion cysts should be considered in ultrasound reporting, since they add useful information about the diagnosis of associated rheumatic conditions.

The switch from etanercept originator to SB4: data from a real-life experience on tolerability and persistence on treatment in joint inflammatory diseases.

AIMS: Switching from originator to biosimilar is part of current practice in inflammatory rheumatic musculoskeletal diseases (iRMDs) such as rheumatoid arthritis (RA), psoriatic arthritis (PsA) and axial spondylarthritis (axSpA), with evidences derived from both etanercept (ETN) to SB4-switching randomized controlled trials and real-life registries. We investigated the safety and treatment persistence of ETN/SB4 in a multi-iRMD cohort derived from two rheumatology departments in our region. METHODS: Adult patients with iRMDs, treated with ETN for at least 6 months and switched to SB4 in stable clinical condition, were eligible for this retrospective evaluation. Retrospective data on adverse events, loss of efficacy and persistence on treatment were collected until latest available follow-up. RESULTS: A total of 220 patients (85 RA, 81 PsA, 33 axSpA, 14 juvenile idiopathic arthritis and seven other conditions; 142 females, mean age 58 ± 7 years, disease duration 12 ± 4 years, ETN duration 7 ± 4 years) were enrolled, with median follow-up of 12.1 (9.7-15.8) months. A total of 50 patients (22.7%) presented with at least one adverse event, with 36 (16.4%) disease flares and 30 (13.6%: 11 for safety and 19 loss of efficacy) SB4 withdrawals. Cumulative SB4 treatment persistence was 99.1%, 88.6% and 64.6% at 6, 12 and 18 months respectively. Back-switch to ETN was performed in 17/30 cases, the remaining cases were managed with change of biologic disease modifying or conventional synthetic anti-rheumatic drug. Age was the only significant predictor of SB4 interruption at 6 months. CONCLUSION: Our real-life data confirm the safety profile of switching from ETN to SB4, with slightly higher treatment persistence rates compared with other real-life registries.

The Tim-3-Galectin-9 Pathway and Its Regulatory Mechanisms in Human Breast Cancer.

Human cancer cells operate a variety of effective molecular and signaling mechanisms which allow them to escape host immune surveillance and thus progress the disease. We have recently reported that the immune receptor Tim-3 and its natural ligand galectin-9 are involved in the immune escape of human acute myeloid leukemia (AML) cells. These cells use the neuronal receptor latrophilin 1 (LPHN1) and its ligand fibronectin leucine rich transmembrane protein 3 (FLRT3, and possibly other ligands) to trigger the pathway. We hypothesized that the Tim-3-galectin-9 pathway may be involved in the immune escape of cancer cells of different origins. We found that studied breast tumors expressed significantly higher levels of both galectin-9 and Tim-3 compared to healthy breast tissues of the same patients and that these proteins were co-localized. Increased levels of LPHN2 and expressions of LPHN3 as well as FLRT3 were also detected in breast tumor cells. Activation of this pathway facilitated the translocation of galectin-9 onto the tumor cell surface, however no secretion of galectin-9 by tumor cells was observed. Surface-based galectin-9 was able to protect breast carcinoma cells against cytotoxic T cell-induced death. Furthermore, we found that cell lines from brain, colorectal, kidney, blood/mast cell, liver, prostate, lung, and skin cancers expressed detectable amounts of both Tim-3 and galectin-9 proteins. The majority of cell lines expressed one of the LPHN isoforms and FLRT3. We conclude that the Tim-3-galectin-9 pathway is operated by a wide range of human cancer cells and is possibly involved in prevention of anti-tumor immunity.

High mobility group box 1 (HMGB1) acts as an "alarmin" to promote acute myeloid leukaemia progression.

High mobility group box 1 (HMGB1) is a non-histone protein localised in the cell nucleus, where it interacts with DNA and promotes nuclear transcription events. HMGB1 levels are elevated during acute myeloid leukaemia (AML) progression followed by participation of this protein in triggering signalling events in target cells as a pro-inflammatory stimulus. This mechanism was hypothesised to be employed as a survival pathway by malignant blood cells and our aims were therefore to test this hypothesis experimentally. Here we report that HMGB1 triggers the release of tumour necrosis factor alpha (TNF-α) by primary human AML cells. TNF-α induces interleukin 1 beta (IL-1ß) production by healthy leukocytes, leading to IL-1ß-induced secretion of stem cell factor (SCF) by competent cells (for example endothelial cells). These results were verified in mouse bone marrow and primary human AML blood plasma samples. In addition, HMGB1 was found to induce secretion of angiogenic vascular endothelial growth factor (VEGF) and this process was dependent on the immune receptor Tim-3. We therefore conclude that HMGB1 is critical for AML progression as a ligand of Tim-3 and other immune receptors thus supporting survival/proliferation of AML cells and possibly the process of angiogenesis.

Highly specific targeting of human acute myeloid leukaemia cells using pharmacologically active nanoconjugates.

In this study we used 5 nm gold nanoparticles as delivery platforms to target cancer cells expressing the immune receptor Tim-3 using single chain antibodies. Gold surfaces were also covered with the cytotoxic drug rapamycin which was immobilised using a glutathione linker. These nanoconjugates allowed highly specific and efficient delivery of cytotoxic rapamycin into human malignant blood cells.

A Human Bi-specific Antibody against Zika Virus with High Therapeutic Potential.

Zika virus (ZIKV), a mosquito-borne flavivirus, causes devastating congenital birth defects. We isolated a human monoclonal antibody (mAb), ZKA190, that potently cross-neutralizes multi-lineage ZIKV strains. ZKA190 is highly effective in vivo in preventing morbidity and mortality of ZIKV-infected mice. NMR and cryo-electron microscopy show its binding to an exposed epitope on DIII of the E protein. ZKA190 Fab binds all 180 E protein copies, altering the virus quaternary arrangement and surface curvature. However, ZIKV escape mutants emerged in vitro and in vivo in the presence of ZKA190, as well as of other neutralizing mAbs. To counter this problem, we developed a bispecific antibody (FIT-1) comprising ZKA190 and a second mAb specific for DII of E protein. In addition to retaining high in vitro and in vivo potencies, FIT-1 robustly prevented viral escape, warranting its development as a ZIKV immunotherapy.

The Tim-3-galectin-9 Secretory Pathway is Involved in the Immune Escape of Human Acute Myeloid Leukemia Cells.

Acute myeloid leukemia (AML) is a severe and often fatal systemic malignancy. Malignant cells are capable of escaping host immune surveillance by inactivating cytotoxic lymphoid cells. In this work we discovered a fundamental molecular pathway, which includes ligand-dependent activation of ectopically expressed latrophilin 1 and possibly other G-protein coupled receptors leading to increased translation and exocytosis of the immune receptor Tim-3 and its ligand galectin-9. This occurs in a protein kinase C and mTOR (mammalian target of rapamycin)-dependent manner. Tim-3 participates in galectin-9 secretion and is also released in a free soluble form. Galectin-9 impairs the anti-cancer activity of cytotoxic lymphoid cells including natural killer (NK) cells. Soluble Tim-3 prevents secretion of interleukin-2 (IL-2) required for the activation of cytotoxic lymphoid cells. These results were validated in ex vivo experiments using primary samples from AML patients. This pathway provides reliable targets for both highly specific diagnosis and immune therapy of AML.

Balance of Anti-CD123 Chimeric Antigen Receptor Binding Affinity and Density for the Targeting of Acute Myeloid Leukemia.

Chimeric antigen receptor (CAR)-redirected T lymphocytes are a promising immunotherapeutic approach and object of pre-clinical evaluation for the treatment of acute myeloid leukemia (AML). We developed a CAR against CD123, overexpressed on AML blasts and leukemic stem cells. However, potential recognition of low CD123-positive healthy tissues, through the on-target, off-tumor effect, limits safe clinical employment of CAR-redirected T cells. Therefore, we evaluated the effect of context-dependent variables capable of modulating CAR T cell functional profiles, such as CAR binding affinity, CAR expression, and target antigen density. Computational structural biology tools allowed for the design of rational mutations in the anti-CD123 CAR antigen binding domain that altered CAR expression and CAR binding affinity without affecting the overall CAR design. We defined both lytic and activation antigen thresholds, with early cytotoxic activity unaffected by either CAR expression or CAR affinity tuning but later effector functions impaired by low CAR expression. Moreover, the anti-CD123 CAR safety profile was confirmed by lowering CAR binding affinity, corroborating CD123 is a good therapeutic target antigen. Overall, full dissection of these variables offers suitable anti-CD123 CAR design optimization for the treatment of AML.

The immune receptor Tim-3 acts as a trafficker in a Tim-3/galectin-9 autocrine loop in human myeloid leukemia cells.

The immune receptor Tim-3 is often highly expressed in human acute myeloid leukemia (AML) cells where it acts as a growth factor and inflammatory receptor. Recently, it has been demonstrated that Tim-3 forms an autocrine loop with its natural ligand galectin-9 in human AML cells. However, the pathophysiological functions of Tim-3 in human AML cells remain unclear. Here, we report for the first time that Tim-3 is required for galectin-9 secretion in human AML cells. However, this effect is cell-type specific and was found so far to be applicable only to myeloid (and not, for example, lymphoid) leukemia cells. We concluded that AML cells might use Tim-3 as a trafficker for the secretion of galectin-9 which can then be possibly used to impair the anticancer activities of cytotoxic T cells and natural killer (NK) cells.

Differential expression and biochemical activity of the immune receptor Tim-3 in healthy and malignant human myeloid cells.

The T cell immunoglobulin and mucin domain 3 (Tim-3) is a plasma membrane-associated receptor which is involved in a variety of biological responses in human immune cells. It is highly expressed in most acute myeloid leukaemia (AML) cells and therefore may serve as a possible target for AML therapy. However, its biochemical activities in primary human AML cells remain unclear. We therefore analysed the total expression and surface presence of the Tim-3 receptor in primary human AML blasts and healthy primary human leukocytes isolated from human blood. We found that Tim-3 expression was significantly higher in primary AML cells compared to primary healthy leukocytes. Tim-3 receptor molecules were distributed largely on the surface of primary AML cells, whereas in healthy leukocytes Tim-3 protein was mainly expressed intracellularly. In primary human AML blasts, both Tim-3 agonistic antibody and galectin-9 (a Tim-3 natural ligand) significantly upregulated mTOR pathway activity. This was in line with increased accumulation of hypoxia-inducible factor 1 alpha (HIF-1α) and secretion of VEGF and TNF-α. Similar results were obtained in primary human healthy leukocytes. Importantly, in both types of primary cells, Tim-3-mediated effects were compared with those induced by lipopolysaccharide (LPS) and stem cell factor (SCF). Tim-3 induced comparatively moderate responses in both AML cells and healthy leukocytes. However, Tim-3, like LPS, mediated the release of both TNF-α and VEGF, while SCF induced mostly VEGF secretion and did not upregulate TNF-α release.

The immune receptor Tim-3 mediates activation of PI3 kinase/mTOR and HIF-1 pathways in human myeloid leukaemia cells.

The T-cell immunoglobulin and mucin domain 3 (Tim-3) is a plasma membrane-associated protein that is highly expressed in human acute myeloid leukaemia cells. As an acute myeloid leukaemia antigen, it could therefore be considered as a potential target for immune therapy and highly-specific drug delivery. However, a conceptual understanding of its biological role is required before consideration of this protein for therapeutic settings. Here, we reveal the detailed mechanism of action underlying the biological responses mediated by the Tim-3 receptor in myeloid cells. Our studies demonstrate that Tim-3 triggers growth factor type responses in acute myeloid leukaemia cells by activating a phosphatidylinositol-3 kinase (PI-3K)/mammalian target of rapamycin (mTOR) pathway. In addition, the receptor activates hypoxic signalling pathways upregulating glycolysis and pro-angiogenic responses. These findings suggest that Tim-3 could be used as a potential therapeutic target for immune therapy and drug delivery in human acute myeloid leukaemia cells.