A Series of Furimazine Derivatives for Sustained Live-Cell Bioluminescence Imaging and Application to the Monitoring of Myogenesis at the Single-Cell Level.

Bioluminescence (BL) imaging, which utilizes light emitted through the enzymatic reaction of luciferase oxidizing its substrate luciferin, enables sensitive and noninvasive monitoring of life phenomena. Herein, we developed a series of caged furimazine (FMZ) derivatives by introducing a protective group at the C-3 position and a hydroxy group at the C-6 phenyl ring to realize long-term live-cell BL imaging based on the NanoLuc (NLuc)/NanoKAZ (NKAZ)-FMZ system. The membrane permeability and cytotoxicity of the substrates were evaluated and related to their hydrophobicity. Among the series, the derivative with the bulkiest protective group (adamantanecarbonyl group) and a hydroxy substituent (named Ad-FMZ-OH) showed significantly prolonged and constant BL signal in cells expressing NLuc compared to the native FMZ substrate. This derivative enabled continuous BL imaging at the single-cell level for 24 h. Furthermore, we applied Ad-FMZ-OH to BL imaging of myocyte fusion and succeeded in the consecutive and sensitive monitoring at a single-cell level over a day. In summary, NLuc/NKAZ-caged FMZ derivatives have the potential to be applied to live-cell BL imaging of various life phenomena that require long-term observation.

Real-world efficacy of letermovir prophylaxis for cytomegalovirus infection after allogeneic hematopoietic stem cell transplantation: A single-center retrospective analysis.

INTRODUCTION: Cytomegalovirus (CMV) infection is a common complication following allogeneic hematopoietic stem cell transplantation (aHSCT) and is associated with increased mortality. Letermovir (LET) is a novel antiviral drug used to prevent CMV infection. METHODS: We analyzed 111 consecutive patients who underwent aHSCT, retrospectively, to evaluate the efficacy of LET prophylaxis for clinically significant CMV infection (csCMVi) in real-world situations. In addition, we analyzed the influence of LET on transplant outcomes. Thirty-eight patients who were administered LET prophylactically were compared with 73 patients without LET prophylaxis after aHSCT. RESULTS: On day 180, the cumulative incidence of csCMVi in patients who received LET prophylaxis was significantly lower than that in patients without LET prophylaxis (29.7% vs. 56.2%, P < 0.001). Among the patients who developed csCMVi, the interval from aHSCT to the initiation of preemptive therapy was significantly longer in patients who received LET prophylaxis than in those who did not (129.5 days vs. 42 days, P < 0.001). The six-month overall survival was 86.1% in patients who received LET prophylaxis and 66.8% in the non-LET group (P = 0.035). CONCLUSION: LET prophylaxis was highly effective in preventing csCMVi and could potentially improve transplant outcomes, particularly when initiated early after transplantations.

Potential of Single-Molecule Live-Cell Imaging for Chemical Translational Biology.

Single-molecule live-cell imaging is the most direct approach for monitoring the motility of molecules in living cells. Considering the relationship between the motility of molecules and their function, information obtained from single-molecule imaging involves essential clues for understanding the regulatory mechanisms of the processes of target molecules, and translation to applied sciences such as drug discovery. In this Concept, examples of single-molecule imaging studies on G protein-coupled receptors (GPCRs) are mainly introduced, and recent techniques of single-molecule imaging for overcoming the limitation of single-molecule live-cell imaging are discussed. Based on these studies, the prospects of single-molecule imaging will be outlined.

Long-term single cell bioluminescence imaging with C-3 position protected coelenterazine analogues.

Bioluminescence is a powerful imaging modality for monitoring biological phenomena both in vitro and in vivo. Bioluminescence imagin (BLI) is becoming a seamless imaging technology covering the range from cells to organs of small animals. Long-term imaging at the single cell level would lead to a true understanding of the dynamics of life phenomena. This work presents a long-term single cell bioluminescence imaging technology accomplished with C-3 position protected furimazines (FMZs), a CTZ analogues, which generate intense blue emission when paired with a highly stable engineered luciferase, Nanoluc. Four types of FMZs protected at the C-3 position have been synthesized. The type and steric bulkiness of the protection group strongly contributed to storage stability and the kinetics of the bioluminescence reactions of the analogues in human living cells. In particular, two developed FMZ analogues resulted in significantly longer bioluminescence emission with higher S/N ratio than FMZ at single cell level. Long-term bioluminescence single cell imaging technology with the developed FMZ analogues will lead to seamless imaging in the range from cells to organs of small animals.

GM-CSF therapy inhibits chronic graft-versus-host disease via expansion of regulatory T cells.

Regulatory T cells (Tregs) attenuate excessive immune responses, making their expansion beneficial in immune-mediated diseases, including allogeneic bone marrow transplantation associated with graft-versus-host disease (GVHD). In addition to interleukin-2, Tregs require T-cell receptor and costimulatory signals from antigen-presenting cells, such as DCs, for their optimal proliferation. Granulocyte-macrophage colony-stimulating factor (GM-CSF) increases DC number and may promote DC-dependent Treg proliferation. Here, we demonstrate that GM-CSF treatment increases CD4+ CD8- DCs, which are associated with Treg expansion. In a mouse model of chronic GVHD (cGVHD), GM-CSF therapy expanded Tregs, protected against the development of skin GVHD, and regulated both Th1 and Th17 responses in the peripheral lymph nodes, resulting in an attenuation of skin cGVHD. Notably, the expanded Tregs were instrumental to GM-CSF-mediated cGVHD inhibition, which was dependent upon an increased ratio of Tregs to conventional T cells rather than augmentation of suppressive function. These data suggest that GM-CSF induces Treg proliferation by expanding CD4+ CD8- DCs, which in turn regulate alloimmune responses in a cGVHD mouse model. Thus, GM-CSF could be used as a therapeutic DC modulator to induce Treg expansion and to inhibit excessive alloimmune responses in immune-related diseases.

Clinical efficacy of mogamulizumab for relapsed/refractory aggressive adult T-cell leukemia/lymphoma: A retrospective analysis.

OBJECTIVES: Although phase 2 studies have confirmed the efficacy of mogamulizumab for adult T-cell leukemia/lymphoma (ATL), real-world data on its benefits are limited. We assessed the benefits of mogamulizumab for relapsed/refractory ATL in clinical practice. METHODS: We retrospectively analyzed patients with acute- and lymphoma-type ATL. Among 57 patients diagnosed with ATL between January 2008 and August 2018, 42 who received salvage therapy were eligible, including 24 who received mogamulizumab. RESULTS: The overall response rate to mogamulizumab was 54.2%. Median survival time (MST) and 1-year overall survival (OS) rate from mogamulizumab initiation were 7.7 months and 42.0%, respectively. Patients with acute-type ATL showed longer MST (15.1 months) and higher 1-year OS (63.6%). MST without skin rash was 5.0 months, and 1-year OS was 34.3%; however, MST with skin rash was not reached and 1-year OS was 66.7%. Among patients who received the salvage therapy, longer MST and higher 1-year OS were observed with mogamulizumab than without mogamulizumab (P = .078; 9.2 vs. 3.9 months; 47.9% vs. 17.6%, respectively). Mogamulizumab administration improved prognosis in patients with acute-type ATL and skin rash. CONCLUSIONS: In clinical practice, mogamulizumab improved OS in patients with relapsed/refractory ATL, especially those with acute-type ATL and skin rash.

Efficacy and safety of anagrelide as a first-line drug in cytoreductive treatment-naïve essential thrombocythemia patients in a real-world setting.

OBJECTIVE: This study aimed to retrospectively assess the efficacy and safety of anagrelide in cytoreduction therapy-naïve essential thrombocythemia (ET) patients in a real-world setting. METHOD: Data from 53 ET patients who received anagrelide as a first-line therapy were reviewed for patient characteristics, antiplatelet status, cytoreduction status, therapeutic effects, adverse events, thrombohemorrhagic event development, progression to myelofibrosis or acute leukemia, and cause of death. RESULTS: The rate of achieving a platelet count of <600 × 109 /L during anagrelide monotherapy was 83.0%. Adverse events occurred in 32 of 53 patients, and tended to be slightly more severe in patients with cardiac failure; however, they were mostly tolerable. The therapeutic effect of anagrelide was consistent, regardless of genetic mutation profiles. The incidence of anemia as an adverse event was significantly higher in the CALR mutation-positive group. Favorable platelet counts were also achieved in patients for whom hydroxyurea was introduced as a replacement for anagrelide or in addition to anagrelide because of unresponsiveness or intolerance to treatment. CONCLUSION: In Japanese cytoreduction therapy-naïve ET patients, anagrelide administration as a first-line therapy demonstrated favorable effects in reducing platelet counts, and its safety profile that was generally consistent with those in previous reports.

Protein Dynamics of the Sensor Protein HemAT as Probed by Time-Resolved Step-Scan FTIR Spectroscopy.

The heme-based aerotactic transducer (HemAT) is an oxygen-sensor protein consisting of a sensor and a signaling domain in the N- and C-terminal regions, respectively. Time-resolved step-scan FTIR spectroscopy was employed to characterize protein intermediate states obtained by photolysis of the carbon monoxide complexes of sensor-domain, full-length HemAT, and the Y70F (B-helix), L92A (E-helix), T95A (E-helix), and Y133F (G-helix) HemAT mutants. We assign the spectral components to discrete substructures, which originate from a helical structure that is solvated (1638 cm-1) and a native helix that is protected from solvation by interhelix tertiary interactions (1654 cm-1). The full-length protein is characterized by an additional amide I absorbance at 1661 cm-1, which is attributed to disordered structure suggesting that further protein conformational changes occur in the presence of the signaling domain in the full-length protein. The kinetics monitored within the amide I absorbance of the polypeptide backbone in the sensor domain exhibit two distinct relaxation phases (t1 = 24 and t2 = 694 µs), whereas that of the full-length protein exhibits monophasic behavior for all substructures in a time range of t = 1253-2090 µs. These observations can be instrumental in monitoring helix motion and the role of specific mutants in controlling the dynamics in the communication pathway from the sensor to the signaling domain. The kinetics observed for the amide I relaxation for the full-length protein indicate that the discrete substructures within full-length HemAT, unlike those of the sensor domain, relax independently.

Live Cell Imaging of Endogenous RNAs Using Pumilio Homology Domain Mutants: Principles and Applications.

Recently, dynamic changes in the location of RNA in space and time in living cells have become a target of interest in biology because of their essential roles in controlling physiological phenomena. To visualize RNA, methods for the fluorescent labeling of RNA in living cells have been developed. For RNA labeling, oligonucleotide-based RNA probes have mainly been used because of their high selectivity for target RNAs. By contrast, protein-based RNA probes have not been used widely because of their lack of design flexibility, although they have various potential advantages compared with nucleotide-based probes, such as controllability of intracellular localization, high detectability, and ease of introduction into cells and transgenic organisms in a cell type and tissue specific manner by genetic engineering techniques. This Perspective focuses on a possible approach to the development of protein-based RNA probes using Pumilio homology domain (PUM-HD) mutants. The PUM-HD is a domain of an RNA binding protein that allows custom-made modifications to recognize a given eight-base RNA sequence. PUM-HD-based RNA probes have been applied to visualize various RNAs in living cells. Here, the techniques and RNA imaging results obtained using the PUM-HD are introduced.

A robust split-luciferase-based cell fusion screening for discovering myogenesis-promoting molecules.

Myogenesis-promoting chemicals are an important source of new pharmaceuticals for the treatment of skeletal muscle atrophy that impairs quality of life. This report presents a robust and quantitative bioluminescence-based assay for screening myogenesis-promoting compounds in chemical libraries. The assay system consists of two stable C2C12 myoblast cell lines, each of which expresses either an N-terminal or a C-terminal split luciferase fragment fused to a naturally split DnaE intein as an indicator for cell fusion. Cell fusion during myogenesis induces bioluminescence in the cytosol because of the reconstitution of luciferases. The luminescence intensity quantitatively represents the progress in the cell fusion and therefore indicates the extent of myogenesis. We applied this assay system to a high-throughput screening of myogenesis-promoting compouns in 1191 pharmacologically proven bioactive small molecules, which revealed two chemical compounds as myogenesis-promoting compounds: Imatinib and Doxazosin mesylate. The assay system enabled a robust and quantitative evaluation of the extent of myogenesis through simple luminescence measurements, and is expected to be widely applicable for high-throughput screening of cell fusion-promoting and inhibiting molecules.

[Successful treatment with brentuximab vedotin maintenance therapy after autologous stem cell transplantation in high-risk Hodgkin lymphoma].

A 56-year-old woman was diagnosed with classical Hodgkin lymphoma in December 2012. She achieved complete remission (CR) with six cycles of adriamycin, bleomycin, vinblastine, and dacarbazine (ABVD). In March 2015, she experienced a relapse marked by high fever, respiratory discomfort, and pain in the left thigh owing to tumor involvement of the femur. She was treated with one cycle of brentuximab vedotin (BV), followed by irradiation of the left femoral lesion. She achieved partial remission (PR) but developed recurrence after the third cycle of BV. She achieved PR again with two cycles of standard bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone (BEACOPP) regimen; therefore, autologous stem cell transplantation (ASCT) was performed. Because the dosing interval used for BV therapy was longer than that in the recommended schedule, we could not definitively attribute her recurrence to BV resistance. Moreover, she maintained a good performance status after recurrence during subsequent cycles of BV therapy. Because of attaining PR after ASCT, she subsequently received a total of 12 BV cycles for consolidation. She achieved CR 3 months after ASCT and has remained in CR until 29 months. For patients who show relapse after initial BV therapy, retreatment with BV should be carefully considered. Patients who show relapse after achieving at least PR with initial BV therapy are potential candidates for post-ASCT BV maintenance therapy to reduce their tumor burden.

Probing the Role of the Heme Distal and Proximal Environment in Ligand Dynamics in the Signal Transducer Protein HemAT by Time-Resolved Step-Scan FTIR and Resonance Raman Spectroscopy.

HemAT is a heme-containing oxygen sensor protein that controls aerotaxis. Time-resolved step-scan FTIR studies were performed on the isolated sensor domain and full-length HemAT proteins as well as on the Y70F (B-helix), L92A (E-helix), T95A (E-helix), and Y133F (G-helix) mutants to elucidate the effect of the site-specific mutations on the ligand dynamics subsequent to CO photolysis. The mutations aimed to perturb H-bonding and electrostatic interactions near the heme Fe-bound gaseous ligand (CO) and the heme proximal environment. Rebinding of CO to the heme Fe is biphasic in the sensor domain and full-length HemAT as well as in the mutants, with the exception of the Y133F mutant protein. The monophasic rebinding of CO in Y133F suggests that in the absence of the H-bond between Y133 and the heme proximal H123 residue the ligand rebinding process is significantly affected. The role of the proximal environment is also probed by resonance Raman photodissociation experiments, in which the Fe-His mode of the photoproduct of sensor domain HemAT-CO is detected at a frequency higher than that of the deoxy form in the difference resonance Raman spectra. The role of the conformational changes of Y133 (G-helix) and the role of the distal L92 and T95 residues (E-helix) in regulating ligand dynamics in the heme pocket are discussed.

Realistic Lenalidomide Dose Adjustment Strategy for Transplant-Ineligible Elderly Patients with Relapsed/Refractory Multiple Myeloma: Japanese Real-World Experience.

Lenalidomide is an immunomodulatory drug administered orally in the treatment of multiple myeloma. Some elderly patients require a reduced lenalidomide dose because of comorbidities and/or adverse events. This study investigated the actual dose of lenalidomide in elderly patients, finding that most received reduced (5-10 mg) doses. The most common reasons for dose reduction were renal dysfunction (54% of patients), fatigue (grade ≥3; 20%), hematologic disorder (grade ≥3; 14%), and rash (grade ≥3; 9%). Their median time to progression was 11.8 months and their median overall survival was 39.2 months. The overall response rate was 73%, including 17% with a complete response, 19% with a very good partial response, and 37% with a partial response. These results showed that, contrary to western countries, most patients were treated with a reduced dose of lenalidomide in Japan. However, it is suggested that continued treatment with a tolerable dose may yield favorable outcomes.

Genetically Encoded Fluorescent Probe for Imaging Apoptosis in Vivo with Spontaneous GFP Complementation.

Apoptosis plays a pivotal role in development and tissue homeostasis in multicellular organisms. Dysfunction of apoptosis is involved in many fatal diseases such as cancer. Visualization of apoptosis in living animals is necessary to understand the mechanism of apoptosis-related diseases. Here, we describe a genetically encoded fluorescent probe for imaging apoptosis in living multicellular organisms, based on spontaneous complementation of two fragments of a green fluorescent protein (GFP) variant (GFP OPT). The probe is designed for detection of mitochondria-mediated apoptosis during which a mitochondrial protein of Smac is released into cytosol. The Smac is connected with a carboxy-terminal fragment of GFP OPT (GFP11), whereas the remainder of GFP OPT (GFP(1-10)) is located in the cytosol. Under an apoptotic condition, the Smac is released from mitochondria into cytosol, allowing complementation of the GFP-OPT fragments and the emission of fluorescence. Live-cell imaging demonstrates that the probe enables detection of apoptosis in living cells with a high signal-to-background ratio. We applied the probe to living zebrafish, in which apoptotic cells were visualized with fluorescence. The technique provides a useful tool for the study of apoptosis in living animals, facilitating elucidation of the mechanisms of apoptosis-related diseases.

Rapid improvement of hyperammonemic encephalopathy by bortezomib treatment in IgD-type multiple myeloma.

A 74-year-old man visited our hospital with complaints of anorexia, weight loss, and impaired activities of daily living. He presented mild consciousness disturbance at the first visit, but specific causes were identified. The IgD level was>2,000 mg/dl and bone marrow biopsy was performed after aspiration failed due to excessive density. He was diagnosed with IgD/λ multiple myeloma (MM). He lapsed into a coma with an extremely high ammonia level of 484 µg/dl on day 8 after admission. His diagnosis was established as hyperammonemic encephalopathy (HE). He was treated with dexamethasone (Dex) pulse therapy and continuous hemodiafiltration. Minor improvement of hyperammonemia was achieved. Combination therapy with bortezomib and Dex was commenced. His ammonia level rapidly decreased and his mental state improved. HE accompanied by MM is rare and further studies are needed to clarify outcomes in response to treatment using the novel agent Bor. Although HE is potentially fatal, we found Bor to be rapidly effective against HE.

Simultaneous time-lamination imaging of protein association using a split fluorescent timer protein.

Studies of temporal behaviors of protein association in living cells are crucially important for elucidating the fundamental roles and the mechanism of interactive coordination for cell activities. We developed a method for investigating the temporal alternation of a particular protein assembly using monomeric fluorescent proteins, fluorescent timers (FTs), of which the fluorescent color changes from blue to red over time. We identified a dissection site of the FTs, which allows complementation of the split FT fragments. The split fragments of each FT variant recovered their fluorescence and maintained inherent rates of the color changes upon the reassembly of the fragments in vitro. We applied this method to visualize the aggregation process of α-synuclein in living cells. The size of the aggregates with the temporal information was analyzed from ratio values of the blue and red fluorescence of the reconstituted FTs, from which the aggregation rates were evaluated. This method using the split FT fragments enables tracing and visualizing temporal alternations of various protein associations by single fluorescence measurements at a given time point.

[Primary Central Nervous System Post-Transplant Lymphoproliferative Disorder in a Patient with Acute Lymphocytic Leukemia].

A 27-year-old woman with acute lymphocytic leukemia, who underwent allogeneic hematopoietic stem cell transplantation, complained of nausea and blurred vision 288 days after the transplantation. Intracranial tumors were identified on brain MRI. She received whole brain radiation after open biopsy, but she died. The tumors had characteristics of diffuse large B cell lymphoma, and she was finally diagnosed with primary central nervous system post-transplant lymphoproliferative disorder. This disease is rare and has a poor outcome. Therefore, accumulation of cases and establishment of treatments for this condition are urgently needed.

Methods of split reporter reconstitution for the analysis of biomolecules.

Intracellular signaling inside living cells is controlled by the specific localization of biomolecules, including proteins, with timescales ranging from milliseconds to several hours. To elucidate the related spatial and temporal signal processes, development of optical probes for cellular events is a challenging task in present studies. Herein, we describe recent advances in the basic design of the optical probes, which have been inspired by luminescent creatures, and their practical application to visualize intracellular events in living cells and animals. A discussion of different probe designs reveals their benefits and shortcomings.

Intracellular tau fragment droplets serve as seeds for tau fibrils.

Intracellular tau aggregation requires a local protein concentration increase, referred to as "droplets". However, the cellular mechanism for droplet formation is poorly understood. Here, we expressed OptoTau, a P301L mutant tau fused with CRY2olig, a light-sensitive protein that can form homo-oligomers. Under blue light exposure, OptoTau increased tau phosphorylation and was sequestered in aggresomes. Suppressing aggresome formation by nocodazole formed tau granular clusters in the cytoplasm. The granular clusters disappeared by discontinuing blue light exposure or 1,6-hexanediol treatment suggesting that intracellular tau droplet formation requires microtubule collapse. Expressing OptoTau-ΔN, a species of N-terminal cleaved tau observed in the Alzheimer's disease brain, formed 1,6-hexanediol and detergent-resistant tau clusters in the cytoplasm with blue light stimulation. These intracellular stable tau clusters acted as a seed for tau fibrils in vitro. These results suggest that tau droplet formation and N-terminal cleavage are necessary for neurofibrillary tangles formation in neurodegenerative diseases.

Concomitant use of interleukin-2 and tacrolimus suppresses follicular helper T cell proportion and exerts therapeutic effect against lupus nephritis in systemic lupus erythematosus-like chronic graft versus host disease.

Introduction: Defective interleukin-2 (IL-2) production contributes to immune system imbalance in patients with systemic erythematosus lupus (SLE). Recent clinical studies suggested that low-dose IL-2 treatment is beneficial for SLE and the therapeutic effect is associated with regulatory T cell (Treg) expansion. Pharmacological calcineurin inhibition induces a reduction in the number of Tregs because they require stimulation of T cell receptor signaling and IL-2 for optimal proliferation. However, the activation of T cell receptor signaling is partially dispensable for the expansion of Tregs, but not for that of conventional T cells if IL-2 is present. Aim: We examined whether addition of IL-2 restores the Treg proportion even with concurrent use of a calcineurin inhibitor and if the follicular helper T cell (Tfh) proportion is reduced in an SLE-like murine chronic graft versus host disease model. Methods: Using a parent-into-F1 model, we investigated the effect of IL-2 plus tacrolimus on Treg and Tfh proportions and the therapeutic effect. Results: Treatment with a combination of IL-2 and tacrolimus significantly delayed the initiation of proteinuria and decreased the urinary protein concentration, whereas tacrolimus or IL-2 monotherapy did not significantly attenuate proteinuria. Phosphorylation of signal transducer and activator of transcription 3, a positive regulator of Tfh differentiation, was reduced by combination treatment, whereas phosphorylation of signal transducer and activator of transcription 5, a negative regulator, was not reduced. Conclusion: Addition of calcineurin inhibitors as adjunct agents may be beneficial for IL-2-based treatment of lupus nephritis.