Activated mesenchymal stem/stromal cells promote myeloid cell differentiation via CCL2/CCR2 signaling

Myeloid cells, which originate from hematopoietic stem/progenitor cells (HSPCs), play a crucial role in mitigating infections. This study aimed to explore the impact of mesenchymal stem/stromal cells (MSCs) on the differentiation of HSPCs and progenitors through the C-C motif chemokine CCL2/CCR2 signaling pathway. Murine MSCs, identified as PDGFRα+Sca-1+ cells (PαS cells), were found to secrete CCL2, particularly in response to lipopolysaccharide stimulation. MSC-secreted CCL2 promoted the differentiation of granulocyte/macrophage progenitors into the myeloid lineage. MSC-derived CCL2 plays an important role in the early phase of myeloid cell differentiation in vivo. Single-cell RNA sequencing analysis confirmed that CCL2-mediated cell fate determination was also observed in human bone marrow cells. These findings provide valuable insights for investigating the in vivo effects of MSC transplantation.

Role of LL-37 in Oral Bacterial DNA Accumulation in Dental Plaque

Dental plaque, a highly structured polymicrobial biofilm, persistently forms in the oral cavity and is a common problem affecting oral health. The role of oral defense factors in either collaborating or disrupting host-microbiome interactions remains insufficiently elucidated. This study aims to explore the role of LL-37, a critical antimicrobial peptide in the oral cavity, in dental plaque formation. Through immunostaining dental plaque specimens, we observed that LL-37 and DNA colocalized in the samples, appearing as condensed clusters. In vitro experiments revealed that LL-37 binds rapidly to oral bacterial DNA, forming high molecular weight, DNase-resistant complexes. This interaction results in LL-37 losing its inherent antibacterial activity. Further, upon the addition of LL-37, we observed a visible increase in the precipitation of bacterial DNA. We also discovered a significant correlation between the levels of the DNA-LL-37 complex and LL-37 within dental plaque specimens, demonstrating the ubiquity of the complex within the biofilm. By using immunostaining on dental plaque specimens, we could determine that the DNA-LL-37 complex was present as condensed clusters and small bacterial cell-like structures. This suggests that LL-37 immediately associates with the released bacterial DNA to form complexes that subsequently diffuse. We also demonstrated that the complexes exhibited similar Toll-like receptor 9-stimulating activities across different bacterial species, including Porphyromonas gingivalis, Fusobacterium nucleatum, Prevotella intermedia, and Streptococcus salivarius. However, these complexes prompted dissimilar activities, such as the production of IL-1β in monocytic cells via both NLRP3 pathway-dependent and pathway-independent mechanisms. This study, therefore, reveals the adverse role of LL-37 in dental plaque, where it binds bacterial DNA to form complexes that may precipitate to behave like an extracellular matrix. Furthermore, the unveiled stimulating properties and species-dependent activities of the oral bacterial DNA-LL-37 complexes enrich our understanding of dental plaque pathogenicity and periodontal innate immune responses.

Impact of non-driver gene mutations on thrombo-haemorrhagic events in ET patients

Risk-adapted therapy is recommended to prevent major clinical complications, such as thrombo-haemorrhagic events, in patients with essential thrombocythaemia (ET). In this study, we analysed the association between non-driver gene mutations and thrombo-haemorrhagic events in 579 patients with ET. ASXL1 and TP53 mutations were frequently identified in patients with ET complicated by thrombosis (22.7% and 23.1%, respectively), and the DNMT3A mutation was frequently identified in patients who experienced haemorrhage (15.2%). Multivariate analyses of thrombosis-free survival (TFS) revealed that ASXL1 and TP53 mutations are associated with thrombosis (hazard ratio [HR] = 3.140 and 3.752 respectively). Patients harbouring the ASXL1 or TP53 mutation had significantly worse TFS rates than those without mutation (p = 0.002 and p < 0.001 respectively). Furthermore, JAK2V617F-mutated patients with accompanying ASXL1 mutations showed significantly shorter TFS compared with those without ASXL1 mutations (p = 0.003). Multivariate analyses of haemorrhage-free survival (HFS) revealed that the DNMT3A mutation (HR = 2.784) is associated with haemorrhage. DNMT3A-mutated patients showed significantly shorter HFS than those without the mutation (p = 0.026). Non-driver gene mutations should be considered in treatment strategies and may provide important information for personalised treatment approaches.

MPL gene mutation is a possible risk factor for thrombosis in patients with essential thrombocythemia in Japan

OBJECTIVES

Since MPL mutation is a rare driver gene mutation found in a small number of essential thrombocythemia (ET) patients, the clinical characteristics of patients with MPL mutations and their association with thrombotic events have not yet been elucidated in Japan.

METHODS

We enrolled 579 Japanese ET patients based on the diagnostic criteria of the WHO classification 2017 and compared clinical characteristics of MPL-mutated patients (n = 22; 3.8%) to JAK2V617F-mutated (n = 299; 51.6%), CALR-mutated (n = 144; 24.9%), and triple-negative (TN) (n = 114; 19.7%) patients.

RESULTS

Thrombosis during follow up was observed in 4 out of 22 (18.2%) in the MPL-mutated group, which was the highest among all driver gene mutation groups (JAK2V617F-mutated, 8.7%; CALR-mutated, 3.5%; TN,1.8%). The MPL- and JAK2V617F-mutated groups had worse thrombosis-free survival (TFS) than the CALR-mutated (p = 0.043) and TN groups (p = 0.006). Univariable analysis revealed that a history of thrombosis was a possible risk factor for thrombosis among MPL-mutated patients (hazard ratio: 9.572, p = 0.032).

CONCLUSIONS

MPL-mutated ET patients should require more intensive management to prevent recurrence of thrombosis.

Secreted mutant calreticulins as rogue cytokines in myeloproliferative neoplasms

Mutant calreticulin (CALR) proteins resulting from a -1/+2 frameshifting mutation of the CALR exon 9 carry a novel C-terminal amino acid sequence and drive the development of myeloproliferative neoplasms (MPNs). Mutant CALRs were shown to interact with and activate the thrombopoietin receptor (TpoR/MPL) in the same cell. We report that mutant CALR proteins are secreted and can be found in patient plasma at levels up to 160 ng/mL, with a mean of 25.64 ng/mL. Plasma mutant CALR is found in complex with soluble transferrin receptor 1 (sTFR1) that acts as a carrier protein and increases mutant CALR half-life. Recombinant mutant CALR proteins bound and activated the TpoR in cell lines and primary megakaryocytic progenitors from patients with mutated CALR in which they drive thrombopoietin-independent colony formation. Importantly, the CALR-sTFR1 complex remains functional for TpoR activation. By bioluminescence resonance energy transfer assay, we show that mutant CALR proteins produced in 1 cell can specifically interact in trans with the TpoR on a target cell. In comparison with cells that only carry TpoR, cells that carry both TpoR and mutant CALR are hypersensitive to exogenous mutant CALR proteins and respond to levels of mutant CALR proteins similar to those in patient plasma. This is consistent with CALR-mutated cells that expose TpoR carrying immature N-linked sugars at the cell surface. Thus, secreted mutant CALR proteins will act more specifically on the MPN clone. In conclusion, a chaperone, CALR, can turn into a rogue cytokine through somatic mutation of its encoding gene.

Non-driver gene mutation analysis in a large cohort of polycythemia vera and essential thrombocythemia

OBJECTIVES

A proportion of patients with polycythemia vera (PV) and essential thrombocythemia (ET) harbor non-driver mutations associated with poor prognosis. In this study, we analyzed the frequency of non-driver mutations in a large Japanese PV and ET cohort. Furthermore, we studied the relationship of these mutations and prognosis in Japanese patients.

METHODS

We enrolled 843 Japanese patients with PV or ET. Non-driver mutations were analyzed by target resequencing using next-generation sequencing. The association of the mutations with the prognosis was estimated using multivariable logistic regression analysis and log-rank test.

RESULTS

Non-driver mutations were detected in 31.1% and 24.5% patients with PV and ET, respectively. Among them, ASXL1 mutations were identified as a risk factor for leukemic/myelofibrotic transformation in PV and ET patients (hazard ratio: 4.68, p = .006). The higher-risk groups of the mutation-enhanced international prognostic system (MIPSS)-PV and MIPSS-ET incorporating non-driver mutations exhibited significantly shorter overall survival compared with the low-risk group (p < .001).

CONCLUSIONS

These results implicate the importance of studying non-driver mutations for predicting the prognosis and survival of Japanese PV and ET patients.

Reevaluation of cardiovascular risk factors for thrombotic events in 580 Japanese patients with essential thrombocythemia

Risk-adapted therapy is recommended to prevent thrombosis in essential thrombocythemia (ET) patients. An advanced age, a history of thrombosis, and the presence of the JAK2V617F mutation are well-defined risk factors for thrombosis in ET; however, the impact of cardiovascular risk (CVR) factors on thrombosis in ET remains elusive. Therefore, we herein investigated the impact of CVR factors on thrombosis in 580 ET patients who met the 2017 World Health Organization Classification diagnostic criteria. A univariate analysis identified hypertriglyceridemia and multiple CVR factors as strong risk factors for thrombosis (hazard ratio [HR] 3.530, 95% confidence interval [CI] 1.630-7.643, P = 0.001 and HR 3.368, 95% CI 1.284-8.833, P = 0.014, respectively) and hyper-LDL cholesterolemia as a potential risk factor (HR 2.191, 95% CI 0.966-4.971, P = 0.061). A multivariate analysis revealed that hypertriglyceridemia was an independent risk factor for thrombosis (HR 3.364, 95% CI 1.541-7.346, P = 0.002). Furthermore, poor thrombosis-free survival was observed in patients with a serum triglyceride level ≥ 1.2 mmol/L (HR = 2.592, P = 0.026 vs. < 1.2 mmol/L) or two or more CVR factors (P = 0.011 vs. no CVR factors and P = 0.005 vs. one CVR factor). These results revealed the impact of CVR factors on thrombosis in ET. Since CVR factors are manageable, lifestyle interventions, such as the control of serum triglyceride levels, may effectively prevent thrombosis in ET patients.

Phase 1 Clinical Trial of PPMX-T003, a Novel Human Monoclonal Antibody Specific for Transferrin Receptor 1, to Evaluate Its Safety, Pharmacokinetics, and Pharmacodynamics

This study aimed to evaluate the safety, pharmacokinetics, and pharmacodynamics of PPMX-T003, a novel human monoclonal antibody for transferrin receptor 1 (TFR1), in healthy individuals. Forty participants were enrolled and randomized to PPMX-T003 dose groups (n = 6/group) and the placebo group (n = 10). The safety and pharmacokinetics profiles were assessed according to the sequential, ascending single-dose intravenous infusions of PPMX-T003 from 0.008 mg/kg to 0.25 mg/kg. Adverse events (AEs) after PPMX-T003 administration occurred in 16 of 30 participants. Any severe AE and AE incidence were not reported, but they tended to increase depending on the dose. Laboratory tests, vital signs, and standard 12-lead electrocardiogram showed no clinically relevant changes. Five participants experienced an infusion-related reaction but recovered on days 5-10. Regarding pharmacokinetics, PPMX-T003 has a nonlinear elimination pattern. PPMX-T003 in the 0.25 mg/kg group showed apparent (>50%) decreased serum levels of reticulocytes from day 3 and sustained moderate (<10%) fall of hematocrit and hemoglobin counts from day 7. In conclusion, the antibody-mediated blockade of TFR1 elicited the expected fall in blood cell levels and showed an acceptable safety profile, supporting the continuing development of PPMX-T003 as a new candidate for polycythemia vera treatment.

A marine sponge-derived lectin reveals hidden pathway for thrombopoietin receptor activation

N-glycan-mediated activation of the thrombopoietin receptor (MPL) under pathological conditions has been implicated in myeloproliferative neoplasms induced by mutant calreticulin, which forms an endogenous receptor-agonist complex that traffics to the cell surface and constitutively activates the receptor. However, the molecular basis for this mechanism is elusive because oncogenic activation occurs only in the cell-intrinsic complex and is thus cannot be replicated with external agonists. Here, we describe the structure and function of a marine sponge-derived MPL agonist, thrombocorticin (ThC), a homodimerized lectin with calcium-dependent fucose-binding properties. In-depth characterization of lectin-induced activation showed that, similar to oncogenic activation, sugar chain-mediated activation persists due to limited receptor internalization. The strong synergy between ThC and thrombopoietin suggests that ThC catalyzes the formation of receptor dimers on the cell surface. Overall, the existence of sugar-mediated MPL activation, in which the mode of activation is different from the original ligand, suggests that receptor activation is unpredictably diverse in living organisms.

Cardiovascular risk factors and underlying pathology and prevalence of lipid plaques in women with acute coronary syndromes in different age groups

Background

An incidence of cardiovascular events increases with age in women. The relationship between cardiovascular risk factors, and the underlying pathology and the prevalence of lipid plaques has not been systematically studied in different age groups in women presented with acute coronary syndromes (ACS).

Purpose

We investigated the underlying pathology and the prevalence of lipid plaques in culprit lesions by optical coherence tomography (OCT) in women with different risk factors.

Methods

A total of 382 women who underwent pre-intervention OCT imaging were included. The underlying pathology and the prevalence of lipid plaques in the culprit lesion was compared between women with and without cardiovascular risk factors (i.e. hypertension, smoking, hyperlipidemia, diabetes mellitus, family history and chronic kidney disease) in three different age groups (&lt;60 yr, 60–70 yr, &gt;70 yr).

Results

The relative prevalence of plaque erosion was higher in younger women (&lt;60 yr) and decreased with age (from 51% to 28%, p&lt;0.001). There was no significant difference in the prevalence of lipid plaques between women with and without risk factors, except a higher prevalence of lipid plaques in current smokers compared to non-smokers (79% vs. 63%, p=0.003). In women with hyperlipidemia, the prevalence of lipid plaques was modest in young ages (&lt;60 yr), but increased steeply with age (p&lt;0.001). The increasing age trend for lipid plaque was also observed in women with hypertension (p=0.03) and current smokers (p=0.01). In women with diabetes mellitus and family history, the prevalence of lipid plaques was high even in young ages (&lt;60 yr) and did not increase with age.

Conclusion

The prevalence of plaque erosion was higher in younger women (&lt;60 yr) and decreased with age. Current smokers had significantly higher prevalence of lipid plaque. Patients with diabetes and positive family history had a higher prevalence of lipid plaque at young age. The prevalence of lipid plaques increased with age particularly in women with hyperlipidemia and hypertension.

Funding Acknowledgement

Type of funding sources: Foundation.

Level of vascular inflammation is higher in acute coronary syndromes compared to chronic coronary disease

Background

Vascular inflammation has been recognized as one of the key factors in the pathogenesis of acute coronary syndromes (ACS). Peri-coronary adipose tissue (PCAT) attenuation by computed tomography angiography (CTA) has emerged as a marker specific for coronary artery inflammation. We examined the relationship between clinical presentation and coronary artery inflammation assessed by PCAT attenuation and coronary plaque characteristics.

Methods

Patients with ACS or stable angina pectoris (SAP) who underwent pre-intervention coronary CTA and optical coherence tomography (OCT) were enrolled. PCAT attenuation was measured around the culprit lesion and in the proximal 40 mm of all coronary arteries. PCAT attenuation and OCT findings were compared between patients with ACS versus SAP.

Results

Among 471 patients (ACS: 198, SAP: 273), PCAT attenuation was higher in ACS patients than in SAP patients both at the culprit plaque level (−67.5±9.6 Hounsfield unit [HU] vs. −71.5±11.0 HU, p&lt;0.001) and the culprit vessel level (−68.3±7.7 HU vs. −71.1±7.9 HU, p&lt;0.001). The mean PCAT attenuation of all 3 coronary arteries was also significantly higher in ACS patients than in SAP patients (−68.8±6.3 HU vs. −70.5±7.1 HU, p=0.007). After adjusting patient characteristics, not only thin-cap fibroatheroma (OR: 2.44; 95% CI: 1.63–3.65) and macrophages (OR: 2.07; 95% CI: 1.34–3.21) but also PCAT attenuation in the culprit plaque (OR: 1.04; 95% CI: 1.02–1.06) was associated with the clinical presentation of ACS.

Conclusions

PCAT attenuation at culprit plaque, culprit vessel, and pan-coronary levels was higher in ACS patients than in SAP patients. Vascular inflammation appears to play a crucial role in the development of ACS.

Funding Acknowledgement

Type of funding sources: None.

Clinical features of acquired erythrocytosis: Low levels of serum erythropoietin in a subset of non-neoplastic erythrocytosis patients

BACKGROUND

Acquired erythrocytosis can be classified into polycythemia vera (PV) and non-neoplastic erythrocytosis (NNE). The vast majority of PV patients harbor JAK2 mutations, but differentiating JAK2 mutation-negative PV from NNE is challenging due to a lack of definitive molecular markers.

METHODS

We studied the clinical features of 121 patients with erythrocytosis of which 47 (38.8%) were JAK2 mutation-positive and also fulfilled the diagnostic criteria for PV, and 67 (55.4%) JAK2 mutation-negative erythrocytosis patients who were diagnosed as NNE. Diagnosis was strictly based on driver mutation analysis and central pathology review.

RESULTS

No JAK2 mutation-negative PV patients were found in our cohort. The NNE group showed significantly younger (p < 0.01) age with higher frequency of smoking (p < 0.001), alcohol consumption (p < 0.001), and diabetes mellitus (p < 0.05), whereas the PV group (n = 47) showed significantly higher white blood cell count, platelet count, and lactate dehydrogenase (p < 0.001). Although serum erythropoietin (EPO) levels were significantly higher in NNE compared to PV (p < 0.001), approximately 40% of the NNE patients had EPO levels below the lower range of normal, fulfilling a minor diagnostic criterion of PV and raising the possibility of PV misdiagnosis.

CONCLUSION

Low EPO levels in JAK2 mutation-negative erythrocytosis may not be a reliable diagnostic criterion for distinguishing PV from NNE.

Causes of Thrombocytosis: A Single-center Retrospective Study of 1,202 Patients

Objective Thrombocytosis can occur as a primary event accompanying hematological diseases or as a secondary event. Since the publication of the World Health Organization classification in 2008, thrombocytosis is now generally defined as a platelet count above 450×10⁹/L. Furthermore, the discovery of driver-gene mutations in myeloproliferative neoplasms (MPNs) has simplified the diagnostic approach for thrombocytosis. To identify the causes of thrombocytosis using this new definition, we conducted a retrospective study. Methods We identified outpatients and inpatients aged 20 years or older with platelet counts >450×10⁹/L in a half-year period at a single institute and analyzed the causes of thrombocytosis and associated clinical characteristics. Results Among 1,202 patients with thrombocytosis, 150 (12.5%) had primary and 999 (83.1%) had secondary thrombocytosis. Of these patients with primary thrombocytosis, 129 (86%) had at least 1 molecular marker indicative of MPNs. The major causes of secondary thrombocytosis were tissue injury (32.2%), infection (17.1%), chronic inflammatory disorders (11.7%) and iron deficiency anemia (11.1%). The median platelet count and the incidence of thrombosis were significantly higher in patients with primary thrombocytosis than in those with secondary thrombocytosis. Conclusion Thrombocytosis mainly occurs as a secondary event; however, it is important to determine the cause of and prevent thrombosis, particularly in cases of primary thrombocytosis.

In silico-labeled ghost cytometry

Characterization and isolation of a large population of cells are indispensable procedures in biological sciences. Flow cytometry is one of the standards that offers a method to characterize and isolate cells at high throughput. When performing flow cytometry, cells are molecularly stained with fluorescent labels to adopt biomolecular specificity which is essential for characterizing cells. However, molecular staining is costly and its chemical toxicity can cause side effects to the cells which becomes a critical issue when the cells are used downstream as medical products or for further analysis. Here, we introduce a high-throughput stain-free flow cytometry called in silico-labeled ghost cytometry which characterizes and sorts cells using machine-predicted labels. Instead of detecting molecular stains, we use machine learning to derive the molecular labels from compressive data obtained with diffractive and scattering imaging methods. By directly using the compressive 'imaging' data, our system can accurately assign the designated label to each cell in real time and perform sorting based on this judgment. With this method, we were able to distinguish different cell states, cell types derived from human induced pluripotent stem (iPS) cells, and subtypes of peripheral white blood cells using only stain-free modalities. Our method will find applications in cell manufacturing for regenerative medicine as well as in cell-based medical diagnostic assays in which fluorescence labeling of the cells is undesirable.

MPL overexpression induces a high level of mutant-CALR/MPL complex: a novel mechanism of ruxolitinib resistance in myeloproliferative neoplasms with CALR mutations

Ruxolitinib (RUX), a JAK1/2-inhibitor, is effective for myeloproliferative neoplasm (MPN) with both JAK2V617 F and calreticulin (CALR) mutations. However, many MPN patients develop resistance to RUX. Although mechanisms of RUX-resistance in cells with JAK2V617 F have already been characterized, those in cells with CALR mutations remain to be elucidated. In this study, we established RUX-resistant human cell lines with CALR mutations and characterized mechanisms of RUX-resistance. Here, we found that RUX-resistant cells had high levels of MPL transcripts, overexpression of both MPL and JAK2, and increased phosphorylation of JAK2 and STAT5. We also found that mature MPL proteins were more stable in RUX-resistant cells. Knockdown of MPL in RUX-resistant cells by shRNAs decreased JAK/STAT signaling. Immunoprecipitation assays showed that binding of mutant CALR to MPL was increased in RUX-resistant cells. Reduction of mutated CALR decreased proliferation of the resistant cells. When resistant cells were cultured in the absence of RUX, the RUX-resistance was reversed, with reduction of the mutant-CALR/MPL complex. In conclusion, MPL overexpression induces higher levels of a mutant-CALR/MPL complex, which may cause RUX-resistance in cells with CALR mutations. This mechanism may be a new therapeutic target to overcome RUX-resistance.

A novel orexin antagonist from a natural plant was discovered using zebrafish behavioural analysis

OBJECTIVE

Phenotypic screening is one of the most practical approaches to the identification of mediators of behaviour, since it is difficult to model brain function in vitro, at a cellular level. We used a zebrafish (Danio rerio) behavioural assay to discover novel, natural, neuroactive compounds.

MATERIALS AND METHODS

A zebrafish behavioural assay was performed for seven natural compounds, obtained from plants. The behavioural profiles were compared to those of known psychoactive drugs. We characterised a natural compound exhibiting a behaviour profile similar to that of suvorexant, using in silico, in vitro and microarray expression analysis.

RESULTS

The behavioural analysis performed in this study classified central nervous system drugs according to their mechanism. Zebrafish treated with a natural compound, 8b-(4'-Hydroxytigloyloxy) costunolide (8b), showed behaviour profiles similar to those of zebrafish treated with suvorexant, a known orexin antagonist. This behavioural assay was validated using in silico and in vitro assays, which revealed that the new compound was a dual orexin receptor antagonist. In addition, transcriptome analysis suggested that 8b might regulate the nuclear factor-κB (NF-κB) related pathway.

CONCLUSIONS

We conclude that zebrafish phenotypic screening, combined with in silico assays and gene expression profiling, is a useful strategy to discover and characterize novel therapeutic compounds, including natural products.

CREB3L1 overexpression as a potential diagnostic marker of Philadelphia chromosome-negative myeloproliferative neoplasms

Discrimination of Philadelphia-negative myeloproliferative neoplasms (Ph-MPNs) from reactive hypercytosis and myelofibrosis requires a constellation of testing including driver mutation analysis and bone marrow biopsies. We searched for a biomarker that can more easily distinguish Ph-MPNs from reactive hypercytosis and myelofibrosis by using RNA-seq analysis utilizing platelet-rich plasma (PRP)-derived RNAs from patients with essential thrombocythemia (ET) and reactive thrombocytosis, and CREB3L1 was found to have an extremely high impact in discriminating the two disorders. To validate and further explore the result, expression levels of CREB3L1 in PRP were quantified by reverse-transcription quantitative PCR and compared among patients with ET, other Ph-MPNs, chronic myeloid leukemia (CML), and reactive hypercytosis and myelofibrosis. A CREB3L1 expression cutoff value determined based on PRP of 18 healthy volunteers accurately discriminated 150 driver mutation-positive Ph-MPNs from other entities (71 reactive hypercytosis and myelofibrosis, 6 CML, and 18 healthy volunteers) and showed both sensitivity and specificity of 1.0000. Importantly, CREB3L1 expression levels were significantly higher in ET compared with reactive thrombocytosis (P < .0001), and polycythemia vera compared with reactive erythrocytosis (P < .0001). Pathology-affirmed triple-negative ET (TN-ET) patients were divided into a high- and low-CREB3L1-expression group, and some patients in the low-expression group achieved a spontaneous remission during the clinical course. In conclusion, CREB3L1 analysis has the potential to single-handedly discriminate driver mutation-positive Ph-MPNs from reactive hypercytosis and myelofibrosis, and also may identify a subgroup within TN-ET showing distinct clinical features including spontaneous remission.

Clinical impacts of the mutational spectrum in Japanese patients with primary myelofibrosis

Patients with primary myelofibrosis (PMF) have a poorer prognosis than those with other subtypes of myeloproliferative neoplasms (MPNs). To investigate the relationship between gene mutations and the prognosis of Japanese PMF patients, we analyzed mutations in 72 regions located in 14 MPN-relevant genes (CSF3R, MPL, JAK2, CALR, DNMT3A, TET2, EZH2, ASXL1, IDH1/2, SRSF2, SF3B1, U2AF1, and TP53) utilizing a target resequencing platform. In our cohort, ASXL1 mutations were more frequently detected in both overt and prefibrotic PMF patients than other mutations. The frequency of ASXL1 mutations was slightly higher among overt PMF patients than among prefibrotic PMF patients (44.6% vs 25.0%, FDR = 0.472). Decision tree classification algorithms revealed that ASXL1, EZH2, and SRSF2 mutations were associated with a poor prognosis for overt PMF. Overall survival was significantly shorter in patients harboring ASXL1, EZH2, or SRSF2 mutations than in those without these mutations (p = 0.03). These results suggest that, as reported in Western countries, MIPSS70 is applicable to Japanese PMF patients and ASXL1, EZH2, and SRSF2 mutations may be utilized as surrogate markers of a poor prognosis.

Occurrence and clinical course of peri-stent contrast staining: comparison between second-generation drug-eluting stents and third generation drug-eluting stents

Background

Peri-stent contrast staining (PSS) has been reported to be associated with very late stent thrombosis.

The aims of this study was to compare the occurrence rate of PSS between second generation drug-eluting stents (2nd DES) and third generation drug-eluting stents (3rd DES), and to identify clinical characteristics associated with PSS.

Methods and results

This study comprised 1899 patients with 2493 de novo lesions treated with 2nd or 3rd DES from October 2015 to September 2018. Follow-up angiography was available for 1883 lesions (75.5%). There were 725 patients with 968 lesions treated with 2nd DES, and 716 patients with 915 lesions treated with 3rd DES. The occurrence of PSS, types of PSS, and VLST related to PSS were compared between 2nd and 3rd DES implantation. Mean follow-up period was 30±12 months. The occurrence rate of PSS and segmental type of PSS were similar between two groups (2nd DES vs. 3rd DES, 1.5% vs. 1.7%, p=0.73, 47% vs. 50%, p=0.85, and respectively). The VLST related to PSS occurred in only one case in 3rd DES group. (0% vs. 6.3%, p=0.33).

Conclusion

The occurrence rate of PSS and clinical course were similar between 2nd and 3rd DES.

Funding Acknowledgement

Type of funding source: None

Predictors for rapid progression of coronary calcification: an optical coherence tomography (OCT) study

Background

The natural progression of coronary calcification has not been systematically studied. In vivo coronary calcium can be evaluated by OCT.

Purpose

To identify the incidence and predictors for rapid progression of coronary calcification.

Methods

Patients with serial OCT imaging at baseline and at 6 months were selected from our database. Changes in calcium index during 6-month follow-up and predictors for progression of calcification were studied. Calcium index was defined as the product of the mean calcium arc and calcium length. Rapid progression of calcification was defined as an increase in calcium index above the median value.

Results

Among 187 patients who had serial OCT imaging, 235 calcified plaques were identified in 108 patients (57.8%) at baseline with median calcium index of 132.0 (Interquartile range 58.5–281.2). After 6 months, the calcium index increased in 95.3% of calcified plaques from 132.0 to 178.2 (p&lt;0.001). In multivariable analysis, diabetes mellitus (DM), chronic kidney disease (CKD), lipid-rich plaque, and macrophages were found to be independent predictors for rapid progression of coronary calcification (table). Interestingly, rapid progression of calcification was associated with a significant reduction of inflammatory features (thin-cap fibroatheroma [TCFA]; baseline 21.2% vs. follow-up 11.9%, p=0.003, macrophages; baseline 74.6% vs. follow-up 61.0%, p=0.001).

Conclusions

This study demonstrated that DM, CKD, lipid-rich plaque, and macrophages were independent predictors for rapid progression of coronary calcification. High level of vascular inflammation may stimulate rapid progression of calcification.

Funding Acknowledgement

Type of funding source: None

Predictors of rapid plaque progression: an optical coherence tomography study

Background

Two patterns of plaque progression have been described: slow linear progression and rapid step-wise progression. The former will cause stable angina when the narrowing reaches a critical threshold, while the latter may lead to acute coronary syndromes or sudden cardiac death.

Purpose

The aim of the study was to identify morphologic predictors for rapid plaque progression.

Methods

Patients who had OCT imaging during the index procedure and follow-up angiography with a minimum of 6-month interval were selected. Non-culprit lesion was defined as a plaque with a diameter stenosis ≥30% on index angiogram. Lesion progression was defined as the decrease of angiographic minimum lumen diameter ≥0.4 mm at follow-up (mean, 7.1 months). Baseline morphological characteristics of the plaques with rapid progression were evaluated by OCT. In a subgroup with follow-up OCT imaging for plaques with progression, morphological changes from baseline to follow-up were assessed.

Results

Among 517 lesions, 50 lesions showed progression. These lesions had a significantly higher prevalence of lipid-rich plaque (76.0% vs. 50.5%), thin-cap fibroatheroma (TCFA) (20.0% vs. 5.8%), layered plaque (60.0% vs. 34.0%), macrophage accumulation (62.0% vs. 42.4%), microvessel (46.0% vs. 29.1%), plaque rupture (12.0% vs. 4.7%), and thrombus (6.0% vs. 1.1%), compared to those without progression. The multivariable analysis identified lipid-rich plaque [odds ratio (OR) 2.17, 95% confidence interval (CI) 1.02–4.62, p=0.045], TCFA (OR 5.85, 95% CI 2.01–17.03, p=0.001), and layered plaque (OR 2.19, 95% CI 1.03–4.17, p=0.040) as predictors of subsequent lesion progression. In a subgroup with follow-up OCT, a new layer was detected in 14/41 (34.1%) plaques.

Conclusions

Lipid-rich plaque, TCFA, and layered plaque were predictors of subsequent rapid plaque progression. A new layer, a signature of rapid progression through plaque disruption and healing, was detected in 1/3 of the cases.

Funding Acknowledgement

Type of funding source: None

Impact of left atrial appendage morphology on the silent cerebral infarction after cryoballoon ablation for atrial fibrillation

Aims

Cryoballoon ablation (CBA) is effective for atrial fibrillation (AF), however acute silent cerebral infarction (SCI) is not uncommon after CBA. This study aimed to clarify the relationship between the morphology of LAA and SCI.

Methods and results

From 2015 to 2019, 207 consecutive patients (65.1±11.4 years, 26.6% of female, 31.4% of persistent AF) who underwent CBA for AF at our hospital were enrolled. All patients were evaluated with computed tomography for LAA before CBA and divided into two groups as chicken wing (CW) group and non-CW group. SCI was evaluated with magnetic resonance imaging at the following day after CBA. As a result, 18.4% of patients have occurred SCI after CBA. Although the patients' background didn't differ between the two groups, the Hounsfield scale (LAA/Aorta ratio) was lower (non-CW vs. CW = 0.68±0.12 vs. 0.73±0.11, p=0.004), and LAA orifice size tended to be larger (16.9±4.6 vs. 15.8±4.1, p=0.053) in non-CW group. SCI significantly occurred in non-CW group (29.5% vs. 11.6%, p=0.003), especially in cauliflower shape of 45.0%. In multivariate analysis, non-CW (p=0.002, Odds ratio 3.2, 95% of CI 1.5–7.0), skipped DOAC before CBA (p=0.04, Odds ratio 6.1, 95% of CI 1.1–115.4), and touch-up ablation in left atrium (p=0.02, Odds ratio 2.8, 95% CI 1.2–6.5) were independent predictors of SCI.

Conclusions

SCI was not rare after CBA for AF. Morphology of LAA was strongly associated with SCI.

Funding Acknowledgement

Type of funding source: None

Circadian variations in pathogenesis of ST-segment elevation myocardial infarction

Background

Previous studies have reported a circadian variation in the onset of ST-segment elevation myocardial infarction (STEMI). However, underlying mechanisms for the circadian variation have not been fully elucidated.

Purpose

We investigated the relationship between onset of STEMI and the underlying pathology using optical coherence tomography (OCT).

Methods

Patients presenting with STEMI were selected from an international, multi-center, longitudinal registry study, which included patients who underwent OCT imaging of the culprit lesion at 11 institutions in 6 countries. Onset of MI was estimated using the time of OCT imaging. Patients were divided into 4 groups based on the estimated time of onset (00:00–05:59, 06:00–11:59, 12:00–17:59, or 18:00–23:59). Underlying pathologies of MI (plaque rupture, plaque erosion, and calcified plaque) were compared among the 4 groups.

Results

Among 648 patients, plaque rupture was diagnosed in 386 patients (59.6%), plaque erosion in 197 patients (30.4%), and calcified plaque in 65 patients (10.0%). A marked circadian variation was detected in the incidence of plaque rupture with a peak at 9:00, whereas it was not evident in plaque erosion or calcified plaque. The probability of plaque rupture increased in the periods of 06:00–11:59 (odds ratio: 2.13, 95% confidence interval: 1.30 to 3.49, p=0.002) and 12:00–17:59 (odds ratio: 2.10, 95% confidence interval: 1.23 to 3.58, p=0.005), compared to the period of 00:00–05:59. This circadian pattern was observed only during weekdays (p=0.013) and it was not evident during the weekend (p=0.742).

Conclusions

Plaque rupture occurred most frequently in the morning and the circadian variation was evident only during the weekdays. Acute MI caused by plaque rupture may be related to catecholamine surge.

Funding Acknowledgement

Type of funding source: None

[Mutant calreticulin and the molecular mechanisms in development of myeloproliferative neoplasms]

This review aimed to evaluate the molecular mechanism underlying the development of myeloproliferative neoplasms (MPN) caused by mutant calreticulin (CALR). This mutation is found in a subset of patients with Philadelphia chromosome-negative MPNs, and it encodes a molecular chaperone. However, it is essentially impossible to elucidate the oncogenic property of mutant CALR from the wild-type CALR function. Studies have reported that mutant CALR forms a homomultimeric complex via intermolecular interaction between novel domains acquired due to a frameshift mutation, gains a high binding affinity for myeloproliferative leukemia protein (MPL), the thrombopoietin receptor, through a presumptive structural change, and acts as an agonist for MPL. In this review, I would like to describe the course of the discovery of this unique molecular mechanism and discuss future scope of research on mutant CALR.

Mechanism underlying the development of myeloproliferative neoplasms through mutant calreticulin

Deregulation of cytokine signaling is frequently associated with various pathological conditions, including malignancies. In patients with myeloproliferative neoplasms (MPNs), recurrent somatic mutations in the calreticulin (CALR) gene, which encodes a molecular chaperone that resides in the endoplasmic reticulum, have been reported. Studies have defined mutant CALR as an oncogene promoting the development of MPN, and deciphered a novel molecular mechanism by which mutant CALR constitutively activates thrombopoietin receptor MPL and its downstream molecules to induce cellular transformation. The mechanism of interaction and activation of MPL by mutant CALR is unique, not only due to the latter forming a homomultimeric complex through a novel mutant‐specific sequence generated by frameshift mutation, but also for its ability to interact with immature asparagine‐linked glycan for eventual engagement with immature MPL in the endoplasmic reticulum. The complex formed between mutant CALR and MPL is then transported to the cell surface, where it induces constitutive activation of downstream kinase JAK2 bound to MPL. Refined structural and cell biological studies can provide an in‐depth understanding of this unusual mechanism of receptor activation by a mutant molecular chaperone. Mutant CALR is also involved in modulation of the immune response, transcription, and intracellular homeostasis, which could contribute to the development of MPN. In the present article, we comprehensively review the current understanding of the underlying molecular mechanisms for mutant molecular chaperone‐induced cellular transformation.

P1912Incidence of silent cerebral thromboembolism in catheter ablation for atrial fibrillation under the use of DOAC: Comparison of cryoballoon versus radiofrequency ablation system

Background

Silent cerebral thromboembolism (CE) in catheter ablation for atrial fibrillation (AF) is not rare. Prior our study has reported lower incidence of silent CE in AF radiofrequency (RF) ablation using irrigated-tip catheter than conventional 4 or 8mm-tip catheter. In addition, the incidence of silent CE in AF ablation under direct oral anticoagulant (DOAC) was equivalent to continuous therapeutic warfarin. Recently pulmonary vein isolation (PVI) using cryoballoon (CB) has emerged as an alternative technique to RF ablation because some studies suggested that the efficacy for PVI by CB was equivalent to RF. However, incidence of silent CE in CB ablation under the use of DOAC is unknown.

Objective

We aimed to evaluate the incidence new silent CE in AF ablation using CB system compared with irrigated RF system under the use of DOAC.

Methods

322 consecutive patients with paroxysmal or persistent AF (155 using CB system, 167 using RF system) who underwent the first AF ablation were taking DOAC more than one month prior to the procedure. Throughout AF ablation procedure, heparin was administered to maintain activated clotting time (ACT) between 300 and 400 seconds. Head MRI was performed in all patients within 24 hours after the procedure.

Results

In 14 (9.0%) patients using CB and in 20 (12.0%) patients using RF, head MRI showed new embolic lesions without neurological symptom (P=0.469). Although the amount of heparin during the procedure in group CB was significantly less than in group RF (16134±3125 U vs. 18689±5222 U; P<0.0001), amount of heparin per hour in group CB was more than in group RF (8335±1955 U/h vs. 6143±1918 U/h; P<0.0001) because procedure time in group CB was shorter than in group RF (121.3±34.1 min vs. 189.5±47.4 min; P<0.0001). Mean ACT in both groups was maintained high level (3367±25.3 sec. vs. 338.6±23.5 sec.; P=0.479). In univariate analysis, minimum ACT during procedure, as before puncture of interatrial septum, were significantly correlated with the incidence of silent CE (P=0.027).

Conclusions

The incidence of silent CE in AF ablation using CB system was lower than RF system, although it was not a significant difference between different ablation techniques for AF. In AF ablation, the use of CB may be preferred rather than RF as ablation system in regard to risk reduction of thromboembolic complications.

P6402Ischemic and bleeding events during dual antiplatelet therapy after second-generation drug-eluting stent implantation in hemodialysis patients: a propensity score-matched analysis

Background

Dual-antiplatelet therapy (DAPT) after second-generation drug eluting stent (2-DES) implantation reduced the risk of stent thrombosis and subsequent ischemic events, with an increase in bleeding risk. Although chronic kidney disease patients have high ischemic and bleeding risk, little is known about both risks in hemodialysis patients after 2-DES implantation during DAPT.

Method

From July 2009 to March 2017, we retrospectively analyzed post-discharge major adverse cardiac and cerebrovascular events [MACCE: cardiac death, myocardial infarction, target vessel revascularization (TVR) and cerebral infarction] and bleeding events in 644 consecutive patients during DAPT after 2-DES implantation. We divided them into 2 groups [102 hemodialysis (HD) and 518 non-hemodialysis (Non-HD) patients, mean age, 71±10 years] after excluding 24 patients (lost to follow up and peritoneal dialysis). Follow-up period was 49±24 months. Median DAPT duration was 12 months. The primary endpoint was MACCE. The secondary endpoint was bleeding events according to the Bleeding Academic Research Consortium (BARC) type 2, 3, or 5. MACCE and bleeding events were compared between HD and Non-HD by using the propensity score-matching (PSM) method.

Results

Among the 620 eligible patients, the primary and secondary events occurred in 207 (33.3%) and 76 (12.3%) patients, respectively. The rates of unadjusted MACCE [HD vs Non-HD: 53.9% vs 29.3%; Hazard ratio (HR) 2.39, p<0.01] and bleeding events (HD vs Non-HD: 21.6% vs 10.4%; HR 2.50, p<0.01) were significantly higher in HD than Non-HD.

After 1-to-1 propensity score adjustment for baseline differences (hypertension, diabetes mellitus, low ejection fraction, low albumin, anemia, and high C-reactive protein), a total of 160 patients (80 HD vs 80 Non-HD) was created. The rate of MACCE [HD vs Non-HD: 52.5% vs 31.3%; adjusted HR 2.04, p<0.01] was significantly higher in HD than Non-HD. Regarding MACCE, cardiac death (HD vs Non-HD: 18.8% vs 8.8%; adjusted HR 2.65, p=0.03) and TVR (HD vs Non-HD: 15.0% vs 6.3%; adjusted HR 2.74, p=0.046) occurred significantly higher in HD. On the other hand, bleeding events did not exhibit significant differences though HD had a numerically higher event rate (HD vs Non-HD: 25.0% vs 16.3%; adjusted HR 1.68, p=0.15), indicating that the bleeding risk in HD would be strongly dependent on the patient's background.

Conclusions

As a result of PSM, HD was shown to contribute to ischemic risk rather than bleeding risk. Even in the 2-DES era, HD was an independent risk factor of cardiac death and TVR. Therefore, further study on the current regimen of DAPT would be necessary while balancing both ischemic and bleeding risk.

P3590Impact of right ventricular branch slow flow phenomenon post percutaneous coronary intervention for acute coronary syndrome to predict sustained right ventricular dysfunction

Background

Although Right Ventricular dysfunction (RVD) is one of the predictor of poor prognosis, it is believed that ischemic RVD after percutaneous coronary intervention (PCI) for acute coronary syndrome (ACS) restores quickly. Because right ventricular perfusion has more ischemic preconditioning compared with left ventricle, due to their complex perfusion system. However, little is known about the time courses of RVD after ACS-PCI andtheir prognosis. We evaluated the relationship between right ventricular branch slow flow phenomenon (RVB-SF) post ACS-PCI in right coronary artery (RCA) and RVD at 6–8 months follow-up.

Method

We retrospectively analyzed consecutive 82 patients who underwent PCI for ACS in proximal or mid portion of RCA from August 2011 to March 2018 in our institution. Finally, both baseline and follow-up data were obtained from 70 patients. We analyzed TIMI frame count (TFC) to confirm the presence of RVB-SF (TFC ≥40 frame) after PCI. We also analyzed right ventricular fractional area change (RVFAC) at baseline and follow-up using echocardiography to detect sustained RVD (RVFAC ≤35%).

Result

We divided the patients into two groups (RVB-SF: 36 patients, RVB non-SF: 34 patients). Patient clinical characteristics were similar in both groups (sex, age, risk factors, medication, onset to balloon time, left ventricular stroke volume, max creatine kinase). Baseline RVFAC and follow-up RVFAC was significantly smaller in RVB-SF than in RVB non-SF, respectively. (27.1±1.7% vs. 38.3±1.8%, 31.4±1.0% vs. 48.7±1.1%, P<0.0001). However, ΔRVFAC (follow-up RVFAC – baseline RVFAC) was similar between groups. The size of inferior vena cava and systolic pulmonary artery pressure at follow-up were similar in both groups (12.1±0.6 mm vs. 11.7±0.7 mm, P=0.67, 25.7±1.5 mmHg vs. 25.2±1.5 mmHg, P=0.82). In RVB non-SF, 10 patients (29.4%) were diagnosed clinical RVAMI. However, follow-up RVFAC were similar and preserved in both groups (RVAMI: 48.1±1.3%, non-RVAMI: 49.9±1.9%, P=0.85). In RVB-SF, 19 patients (52.7%) were diagnosed clinical RVAMI. Follow-up RVFAC did not improved significantly in both groups (RVAMI: 30.4±1.4% vs. non-RVAMI: 32.6±1.5%, P=0.70). Multivariate analysis showed RVB-SF was the only independent predictor of sustained RVD at 6–8 months follow-up after ACS-PCI.

Conclusion

RVB-SF findings after ACS-PCI for RCA could predict sustained RVD at mid-term follow-up, which may indicate future prolonged RVD.

Clinical and molecular features of patients with prefibrotic primary myelofibrosis previously diagnosed as having essential thrombocythemia in Japan

OBJECTIVE

Prefibrotic/early primary myelofibrosis (pre-PMF) and essential thrombocythemia (ET) exhibited different features of bone marrow; however, this is not always easy to judge objectively, making pathologists' distinction often suboptimal. In the WHO 2008 criteria, pre-PMF was not defined as a subgroup of PMF; therefore, affected patients were at a higher risk of misdiagnosis with ET. In this study, we examined the prevalence of pre-PMF patients among those previously diagnosed with ET in Japan.

METHOD

We reviewed bone marrow specimens and clinical and molecular parameters of patients who were previously diagnosed with ET by the WHO 2008 criteria.

RESULTS

Among 107 ET patients, 13 patients were redefined as having pre-PMF. Pre-PMF patients exhibited a higher frequency of MPL mutation and increased platelet counts compared to true ET patients. Molecular analysis revealed the frequencies of high-risk molecular mutations, such as ASXL1, EZH2, and SRSF2, were significantly increased in pre-PMF patients than those in true ET patients.

CONCLUSION

These results demonstrated the value of reexamining clinical records for patients diagnosed with ET by the WHO 2008 criteria and emphasized that adequate examinations of patients' bone marrow are crucial for an accurate diagnosis of pre-PMF and ET.

Molecular features, prognosis, and novel treatment options for pediatric acute megakaryoblastic leukemia

INTRODUCTION

Acute megakaryoblastic leukemia (AMegL) is a rare hematological neoplasm most often diagnosed in children and is commonly associated with Down's syndrome (DS). Although AMegLs are specifically characterized and typically diagnosed by megakaryoblastic expansion, recent advancements in molecular analysis have highlighted the heterogeneity of this disease, with specific cytogenic and genetic alterations characterizing different disease subtypes. Areas covered: This review will focus on describing recurrent molecular variations in both DS and non-DS pediatric AMegL, their role in promoting leukemogenesis, their association with different clinical aspects and prognosis, and finally, their influence on future treatment strategies with a number of specific drugs beyond conventional chemotherapy already under development. Expert opinion: Deep understanding of the genetic and molecular landscape of AMegL will lead to better and more precise disease classification in terms of diagnosis, prognosis, and possible targeted therapies. Development of new therapeutic approaches based on these molecular characteristics will hopefully improve AMegL patient outcomes.

[Development of myeloproliferative neoplasms by mutant calreticulin: underlying mechanisms]

Unique frameshift mutations in the calreticulin (CALR) gene, which encodes a molecular chaperone present in the endoplasmic reticulum, were identified in a subset of patients with myeloproliferative neoplasms (MPNs). Recently, it has been reported that mutant CALR constitutively activates the thrombopoietin (TPO) receptor MPL, even in the absence of TPO, thereby inducing cellular transformation. Hence, the tumorigenic role of mutant CALR in the development of MPNs is now clear; nevertheless, the precise molecular mechanism the interaction between mutant CALR and MPL remains elusive. We recently illustrated that the accumulation of mutant CALR in the Golgi apparatus and its N-glycan binding capacity are needed for its tumorigenic capacity, including the interaction and activation of MPL. These findings implied that mutant CALR recognizes MPL during the receptor maturation using its original property as a molecular chaperone. Although the molecular mechanism underlying the activation of MPL by CALR remains elusive, it became clear that the mechanism of interaction between mutant CALR and MPL is quite different from that of TPO, the natural ligand, and MPL.