An E3 ligase network engages GCN1 to promote the degradation of translation factors on stalled ribosomes.

Ribosomes frequently stall during mRNA translation, resulting in the context-dependent activation of quality control pathways to maintain proteostasis. However, surveillance mechanisms that specifically respond to stalled ribosomes with an occluded A site have not been identified. We discovered that the elongation factor-1α (eEF1A) inhibitor, ternatin-4, triggers the ubiquitination and degradation of eEF1A on stalled ribosomes. Using a chemical genetic approach, we unveiled a signaling network comprising two E3 ligases, RNF14 and RNF25, which are required for eEF1A degradation. Quantitative proteomics revealed the RNF14 and RNF25-dependent ubiquitination of eEF1A and a discrete set of ribosomal proteins. The ribosome collision sensor GCN1 plays an essential role by engaging RNF14, which directly ubiquitinates eEF1A. The site-specific, RNF25-dependent ubiquitination of the ribosomal protein RPS27A/eS31 provides a second essential signaling input. Our findings illuminate a ubiquitin signaling network that monitors the ribosomal A site and promotes the degradation of stalled translation factors, including eEF1A and the termination factor eRF1.

mRNA decoding in human is kinetically and structurally distinct from bacteria.

In all species, ribosomes synthesize proteins by faithfully decoding messenger RNA (mRNA) nucleotide sequences using aminoacyl-tRNA substrates. Current knowledge of the decoding mechanism derives principally from studies on bacterial systems1. Although key features are conserved across evolution2, eukaryotes achieve higher-fidelity mRNA decoding than bacteria3. In human, changes in decoding fidelity are linked to ageing and disease and represent a potential point of therapeutic intervention in both viral and cancer treatment4-6. Here we combine single-molecule imaging and cryogenic electron microscopy methods to examine the molecular basis of human ribosome fidelity to reveal that the decoding mechanism is both kinetically and structurally distinct from that of bacteria. Although decoding is globally analogous in both species, the reaction coordinate of aminoacyl-tRNA movement is altered on the human ribosome and the process is an order of magnitude slower. These distinctions arise from eukaryote-specific structural elements in the human ribosome and in the elongation factor eukaryotic elongation factor 1A (eEF1A) that together coordinate faithful tRNA incorporation at each mRNA codon. The distinct nature and timing of conformational changes within the ribosome and eEF1A rationalize how increased decoding fidelity is achieved and potentially regulated in eukaryotic species.

Construction of Near-Infrared Probes with Remarkable Large Stokes Shift Based on a Novel Purine Platform for the Visualization of mtG4 Upregulation during Mitochondrial Disorder in Somatic Cells and Human Sperms.

G-quadruplex structures within the nuclear genome (nG4) is an important regulatory factor, while the function of G4 in the mitochondrial genome (mtG4) still needs to be explored, especially in human sperms. To gain a better understanding of the relationship between mtG4 and mitochondrial function, it is crucial to develop excellent probes that can selectively visualize and track mtG4 in both somatic cells and sperms. Herein, based on our previous research on purine frameworks, we attempted for the first time to extend the conjugated structure from the C-8 site of purine skeleton and discovered that the purine derivative modified by the C-8 aldehyde group is an ideal platform for constructing near-infrared probes with extremely large Stokes shift (>220 nm). Compared with the compound substituted with methylpyridine (PAP), the molecule substituted with methylthiazole orange (PATO) showed better G4 recognition ability, including longer emission (∼720 nm), more significant fluorescent enhancement (∼67-fold), lower background, and excellent photostability. PATO exhibited a sensitive response to mtG4 variation in both somatic cells and human sperms. Most importantly, PATO helped us to discover that mtG4 was significantly increased in cells with mitochondrial respiratory chain damage caused by complex I inhibitors (6-OHDA and rotenone), as well as in human sperms that suffer from oxidative stress. Altogether, our study not only provides a novel ideal molecular platform for constructing high-performance probes but also develops an effective tool for studying the relationship between mtG4 and mitochondrial function in both somatic cells and human sperms.

Risk factors of early disease progression and decreased survival for multiple myeloma patients after upfront autologous stem cell transplantation.

Multiple myeloma (MM) stands as the second most prevalent hematological malignancy, constituting approximately 10% of all hematological malignancies. Current guidelines recommend upfront autologous stem cell transplantation (ASCT) for transplant-eligible MM patients. This study seeks to delineate factors influencing post-ASCT outcomes in MM patients. Our cohort comprised 150 MM patients from Taipei Veterans General Hospital, with progression-free survival (PFS) as the primary endpoint and overall survival (OS) as the secondary endpoint. A Cox proportional hazards model was employed to discern potential predictive factors for survival. ASCT age ≥ 65 (hazard ratio [HR] 1.94, 95% confidence interval [CI] 1.08-3.47) and the presence of extramedullary disease (HR 2.53, 95% CI 1.53-4.19) negatively impacted PFS. Conversely, treatment response ≥ VGPR before ASCT (HR 0.52, 95% CI 0.31-0.87) and total CD34+ cells collected ≥ 4 × 106 cells/kg on the first stem cell harvesting (HR 0.52, 95% CI 0.32-0.87) were positively associated with PFS. For OS, patients with ISS stage III (HR 2.06, 95% CI 1.05-4.04), the presence of extramedullary disease (HR 3.92, 95% CI 2.03-7.58), light chain ratio ≥ 100 before ASCT (HR 7.08, 95% CI 1.45-34.59), post-ASCT cytomegalovirus infection (HR 9.43, 95% CI 3.09-28.84), and a lower conditioning melphalan dose (< 140 mg/m2; HR 2.75, 95% CI 1.23-6.17) experienced shorter OS. In contrast, post-ASCT day + 15 absolute monocyte counts (D15 AMC) > 500/µl (HR 0.36, 95% CI 0.17-0.79) and post-ASCT day + 15 platelet counts (D15 PLT) > 80,000/µl (HR 0.48, 95% CI 0.24-0.94) were correlated with improved OS. Significantly, early PLT and AMC recovery on day + 15 predicting longer OS represents a novel finding not previously reported. Other factors also align with previous studies. Our study provides real-world insights for post-ASCT outcome prediction beyond clinical trials.

Prognostic factors in patients with bone marrow hemophagocytosis and its association with hematologic malignancies.

Hemophagocytic lymphohistiocytosis (HLH) is a heterogeneous group of hyperinflammatory statuses that are difficult to diagnose and can be life-threatening. Bone marrow (BM) hemophagocytosis is one of the diagnostic criteria according to HLH 2004 diagnostic criteria and HS score. Limited studies have focused on the prognostic factors of BM hemophagocytosis and its association with hematologic malignancies. We aimed to analyze the clinical significance of BM hemophagocytosis. Patients with BM hemophagocytosis, either by cytology or pathology, were enrolled at Taipei Veterans General Hospital from January 2002 to July 2021. Relevant clinical and laboratory data were extracted from medical records. Of 119 patients with BM hemophagocytosis, 57 were diagnosed with hematologic malignancies. The median age of the patients was 58, ranging from 21 to 90. Splenomegaly (adjusted odds ratio [aOR] 2.96; 95% confidence interval [CI] 1.13-7.79) was a risk factor for hematologic malignancies, while autoimmune disease (aOR 0.07; 95% CI 0.01-0.39) and increased D-dimer (aOR 0.25; 95% CI 0.07-0.92) were protective factors. Risk factors for mortality in patients with BM hemophagocytosis were hematologic malignancies (adjusted hazard ratio [aHR] 2.34; 95% CI 1.24-4.44), Eastern Cooperative Oncology Group score ≥3 (aHR 2.42; 95% CI 1.20-4.89) and thrombocytopenia (aHR 3.09; 95% CI 1.04-9.16). In conclusion, among patients with BM hemophagocytosis, splenomegaly was a predictor of hematologic malignancies. Patients with hematologic malignancies, poor performance status, or thrombocytopenia had a higher mortality risk. Further validation studies are warranted.

Risk Factors and Outcomes of Stem Cell Mobilization Failure in Multiple Myeloma Patients.

Introduction: Autologous hematopoietic stem cell transplantation (ASCT) is a well-established treatment for patients with multiple myeloma (MM), and adequate stem cell collection must be assured before ASCT. However, prediction of poor mobilizers (PMs) is still difficult despite several risk factors for mobilization failure having been identified. Methods: We retrospectively analyzed MM patients at Taipei Veterans General Hospital in Taiwan who underwent stem cell collection between October 2006 and August 2020. A CD34+ cell collection of <1 × 106 cells/kg was defined as a mobilization failure. The primary endpoint was mobilization failure. The secondary endpoint was overall survival (OS). Odds ratios (ORs) and 95% confidence intervals (CIs) for mobilization failure were calculated using a logistic regression model. The cumulative incidence of mortality was estimated using the Kaplan-Meier method. Results: In the multivariate analysis, absolute monocyte count <500/µL (adjusted OR 10.75, 95% CI: 1.82-63.57, p = 0.009), platelet count <150,000/µL (adjusted OR 12.49, 95% CI: 2.65-58.89, p = 0.001) before mobilization, and time interval from diagnosis to stem cell harvest ≥180 days (adjusted OR 7.69, 95% CI: 1.61-36.87, p = 0.011) were risk factors for PMs. PM patients had poorer OS compared to patients with successful stem cell collection in the univariate analysis (log-rank test p = 0.027). The predicted probability of PMs was estimated by the multiple logistic regression model with a sensitivity of 84.6% and a specificity of 84.0%. Conclusion: Absolute monocyte count <500/µL, platelet count <150,000/µL, and treatment duration more than 180 days before stem cell mobilization are risk factors for unsuccessful stem cell collection. Our prediction models have high sensitivity and specificity for mobilization failure prediction and allow for early interventions for possible PMs.

Underweight as a risk factor of mortality in patients with newly diagnosed multiple myeloma.

PURPOSE: Multiple myeloma (MM), a clonal plasma cell malignancy, composes around 10% of hematologic malignancies. Though recent advances in treatment have dramatically improved MM survival, some aggressive courses of disease and dismal outcomes still exist. Low body weight, undernutrition, and cachexia are noted at MM diagnosis. We aim to evaluate the impact of low body mass index (BMI) and undernutrition in MM patients. METHODS: We retrospectively analyzed MM patients at Taipei Veterans General Hospital in Taiwan between January 1, 2006 and October 31, 2018. Being underweight is defined as having a BMI of under 18.5 kg/m2. The patient's baseline characteristics, including BMI, serum albumin level, and comorbidities, etc., were recorded. The primary endpoint of the study was all-cause mortality. A Cox regression model was used to estimate the risk factors of mortality. RESULTS: A total of 378 newly diagnosed MM patients were enrolled in this study. The median age of the patients was 69. Thirty patients (7.9%) were underweight at diagnosis. The median overall survival was 1.3 years (95% CI 0.3-5.7) and 5.0 years (95% CI 3.1-5.9) for patients with low BMI and for patients with normal or higher BMI, respectively. In the multivariate analysis, low BMI (95% CI 1.07-4.44), ECOG ≥2 (95% CI 1.02-2.89), hypoalbuminemia (95% CI 1.21-4.01), high LDH (95% CI 1.22-3.49), and light chain ratio > 100 (95% CI 1.06-2.77) were independent risk factors of mortality. CONCLUSION: MM patients who were underweight, with hypoalbuminemia, poor performance status, higher LDH, and light chain ratio > 100 were associated with poor overall survival.

Risk and impact of invasive fungal infections in patients with multiple myeloma.

Infection is associated with great morbidity and mortality in patients with multiple myeloma (MM), but evidence for invasive fungal infections (IFIs) is lacking. We aimed to investigate risk factors for IFI in MM patients and to determine its impact on patients' survival. We retrospectively analyzed MM patients at Taipei Veterans General Hospital in Taiwan between January 2002 and October 2018. MM was diagnosed according to the International Myeloma Working Group criteria. IFI was defined according to the European Organization for Research and Treatment of Cancer/Mycoses Study Group criteria. All risk factors of IFI in MM patients were estimated using Cox regression models in the univariate and multivariate analyses. Of the 623 patients recruited, 22 (3.5%) were diagnosed with proven or probable IFI. Light chain disease (adjusted hazard ratio [HR] 6.74, 95% confidence interval [CI] 2.10-21.66), hemoglobin less than 8 g/dl (adjusted HR 3.34, 95% CI 1.32-8.42), serum albumin < 3.5 g/dl (adjusted HR 3.24, 95% CI 1.09-9.68), and having received allogeneic stem cell transplantation (allo-SCT) (adjusted HR 5.98, 95% CI 1.62-22.03) were significantly associated with IFI in the multivariate analysis. Contracting IFI was in turn associated with early mortality (adjusted HR 11.60, 95% CI 1.26-106.74). Light chain disease, anemia, hypoalbuminemia, and receiving allo-SCT were independent predictors of IFI in MM patients. The early mortality risk is much higher in those encountering IFI. Physicians must be aware of the rare but potentially lethal infections.

Chiral reagents in glycosylation and modification of carbohydrates.

Carbohydrates play a significant role in numerous biological events, and the chemical synthesis of carbohydrates is vital for further studies to understand their various biological functions. Due to the structural complexity of carbohydrates, the stereoselective formation of glycosidic linkages and the site-selective modification of hydroxyl groups are very challenging and at the same time extremely important. In recent years, the rapid development of chiral reagents including both chiral auxiliaries and chiral catalysts has significantly improved the stereoselectivity for glycosylation reactions and the site-selectivity for the modification of carbohydrates. These new tools will greatly facilitate the efficient synthesis of oligosaccharides, polysaccharides, and glycoconjugates. In this tutorial review, we will summarize these advances and highlight the most recent examples.

Risk of hemophagocytic lymphohistiocytosis in adults with fevers of unknown origin: the clinical utility of a new scoring system on early detection.

The diagnosis of hemophagocytic lymphohistiocytosis (HLH) is delayed by most physicians. This study aimed to identify early parameters and suitable scoring systems for the risk of HLH. Clinical and laboratory data collected ≤3 days after admission were defined as early parameters and used to calculate the number of HLH-2004 criteria met and bone marrow (BM) score. Between January 2006 and February 2016, 233 immunocompetent adults with naïve fever of unknown origin who underwent a BM study were enrolled to mimic patients at risk of HLH and randomly assigned into the developmental or validation cohort. Hemophagocytic lymphohistiocytosis was finally diagnosed in 47 patients, with non-Hodgkin lymphoma as the major etiology (51.1%). Upon admission, four-fifths of patients who developed subsequent HLH fulfilled ≤3 of 8 HLH-2004 criteria, and 6 early parameters were independent predictors of HLH: anemia (hemoglobin < 10 g/dL), thrombocytopenia (platelet count < 100 × 103 /µL), leukoerythroblastosis, hyperbilirubinemia (total bilirubin > 2 × upper normal limit), hyperferritinemia (ferritin > 1000 ng/mL), and splenomegaly. Compared with the HLH criteria met upon admission, the BM score was an independent predictor (odds ratio = 1.621; 95% confidence interval, 1.355-1.940) with excellent discrimination (area under the receiver operating characteristic curve = 0.920; 95% confidence interval, 0.883-0.958). The sensitivity and specificity for a BM score cutoff of 10 points were 95% and 75%, respectively. When approaching immunocompetent adults with a continuously high fever, the BM score at initial admission assists with early identification of patients at risk of HLH.

Clinical-associated characteristics and microbiological features of bloodstream nontyphoidal salmonella infection in adult patients receiving allogeneic hematopoietic stem cell transplantation.

Bloodstream nontyphoidal salmonella (NTS) infection is rare, but its associated characteristics and microbiological features in immunocompromised patients are worth paying attention to, particularly for those receiving allogeneic hematopoietic stem cell transplantation (SCT). No studies so far have analyzed post-transplant bloodstream NTS infection. Therefore, we reviewed 423 adult patients undergoing allogeneic hematopoietic SCT from 2003 to 2014. Nine out of four hundred twenty-three patients (2.13%) developed post-transplant bloodstream NTS infection, including two patients who had subsequent or combined metastatic infections. The median age at SCT was 35 years (interquartile range, 29-46) among the nine patients with bloodstream NTS infection. Male patients were predominant (78%). The median onset of bloodstream NTS infection was at 315 days after SCT (range, 207-629). Multivariate analysis revealed that extensive chronic graft-versus-host disease (GVHD) (OR 8.054, p = 0.003) and nonmyeloablative transplant conditioning (OR 4.604, p = 0.037) were significant associated characteristics for NTS infection. Currently, there are no published data analyzing and exploring post-transplant bloodstream NTS infections in adult allogeneic hematopoietic SCT. Our study determined the associated characteristics and microbiological features for this infection.

Prognostic value of ion channel genes in Chinese patients with gliomas based on mRNA expression profiling.

Increasing evidence suggests that ion channels not only regulate electric signaling in excitable cells but also play important roles in the development of human cancer. However, the roles of ion channels in glioma remain controversial. We systematically analyzed the expression patterns of ion channel genes in a cohort of Chinese patients with glioma using whole-genome mRNA expression profiling. First, a molecular signature comprising 47 ion channel genes (IC47) was identified using Spearman's rank correlation test conducted between tumor grade and gene expression. We assigned a risk score based on IC47 to each glioma patient. We demonstrated that the risk score effectively predicted overall survival in glioma patients. Next, we screened IC47 in different molecular glioma subtypes. IC47 showed a Mesenchymal subtype and wild-type IDH1 preference. Gene ontology (GO) analysis and gene set variation analysis (GSVA) for the functional annotation of IC47 showed that patients with high-risk scores tended to exhibit the decreased expression of proteins associated with the apoptosis and cell adhesion, and higher expression of proteins associated with the cell cycle and cell proliferation. These results suggest that ion channel gene expression could improve the subtype classification in gliomas at the molecular level. The findings in the present study have been validated in two independent cohorts.

Isoquinoline-1-Carboxylate as a Traceless Leaving Group for Chelation-Assisted Glycosylation under Mild and Neutral Reaction Conditions.

Glycosyl isoquinoline-1-carboxylate was developed as a novel benchtop stable and readily available glycosyl donor. The glycosylation reaction was promoted by the inexpensive Cu(OTf)2 salt under mild reaction conditions. The copper isoquinoline-1-carboxylate salt was precipitated from the solution and thus rendered a traceless leaving group. Surprisingly, the proton from the acceptor was absorbed by the precipitated metal complex and the reaction mixture remained at neutral pH. The copper-promoted glycosylation was also proven to be completely orthogonal to the gold-promoted glycosylation, and an iterative synthesis of oligosaccharides from benchtop stable anomeric ester building blocks becomes possible under mild reaction conditions.

Rhodium(I)-Catalyzed Benzannulation of Heteroaryl Propargylic Esters: Synthesis of Indoles and Related Heterocycles.

A de novo synthesis of a benzene ring allows for the preparation of a diverse range of heterocycles including indoles, benzofurans, benzothiophenes, carbazoles, and dibenzofurans from simple heteroaryl propargylic esters using a unified carbonylative benzannulation strategy. Multiple substituents can be easily introduced to the C4-C7 positions of indoles and related heterocycles.

Iridium-Catalyzed Dynamic Kinetic Isomerization: Expedient Synthesis of Carbohydrates from Achmatowicz Rearrangement Products.

A highly stereoselective dynamic kinetic isomerization of Achmatowicz rearrangement products was discovered. This new internal redox isomerization provided ready access to key intermediates for the enantio- and diastereoselective synthesis of a series of naturally occurring sugars. The nature of the de novo synthesis also enables the preparation of both enantiomers.

Stereoselective halocyclization of alkenes with N-acyl hemiaminal nucleophiles.

Halocyclization of alkenes was realized using N-acylhemiaminal nucleophiles. High diastereoselectivity could be achieved for the formation of three stereogenic centers in this halogen-mediated cyclization reaction. We also demonstrated that enantioselective bromocyclization of alkenes using N-acylhemiaminal nucleophiles was possible.

Structural and Functional Neural Alterations in Internet Addiction: A Study Protocol for Systematic Review and Meta-Analysis.

A growing number of neuroimaging studies have revealed abnormal brain structural and functional alterations in subjects with internet addiction (IA), however, with conflicting conclusions. We plan to conduct a systematic review and meta-analysis on the studies of voxelbased morphometry (VBM) and resting-state functional connectivity (rsFC), to reach a consolidated conclusion and point out the future direction in this field. A comprehensive search of rsFC and VBM studies of IA will be conducted in the PubMed, Cochrane Library, and Web of Science databases to retrieve studies published from the inception dates to August 2021. If the extracted data are feasible, activation likelihood estimation and seed-based d mapping methods will be used to meta-analyze the brain structural and functional changes in IA patients. This study will hopefully reach a consolidated conclusion on the impact of IA on human brain or point out the future direction in this field.

Long-term outcomes of frontline intensification in primary CNS lymphoma: A real-world single-center experience.

BACKGROUND: Frontline intensification (including consolidative whole-brain radiotherapy or high-dose chemotherapy with autologous stem-cell transplantation after induction therapy) has been proposed to treat primary central nervous system lymphoma (PCNSL). However, no prospective randomized trials have answered whether frontline intensification can offer a survival benefit to PCNSL patients. We aim to clarify the outcomes and survival influence of frontline intensification on real-world patients with different risk-stratified PCNSLs. METHODS: Between January 2003 and December 2016, 110 PCNSL adults were retrospectively included, and 76 patients achieved at least PR after induction therapy, including 38 patients who received frontline intensification. The median follow-up with the 31 survivors was 7.52 years. RESULTS: Of the 38 induction-completed patients who had not received frontline intensification, 95% achieved post-induction therapy CR/CRu; however, all inevitably recurred. In the 38 who received frontline intensification, CR/CRu improved from 45% (pre-frontline intensification) to 84% (post-frontline intensification), and they achieved significantly better PFS (non-reach vs. 522 days, p < 0.001) and OS (non-reach vs. 899 days, p < 0.001). Additionally, patients had similar PFS and OS rates when receiving HDC-ASCT and/or WBRT as frontline intensification. Frontline intensification significantly improved PFS and OS survival in higher-risk patients (intermediate/high IELSG risk, MSKCC group 2/3, or Nottingham/Barcelona score ≥ 2 points) but did not improve OS in lower-risk patients. Among the 38 patients who received frontline intensification, two had treatment-related mortality; 14 recurred after frontline intensification. MTX-based chemotherapy was the main salvage modality, and the median OS was 295 days after recurrence. Progressive disease and infection (especially pneumonia) are two major causes of mortality in patients who receive frontline intensification. CONCLUSIONS: When achieving CR/CRu/PR after induction chemotherapy, frontline intensification should be adopted to improve PFS and OS in real-world PCNSL patients, especially higher-risk patients.

Herpes zoster prophylaxis: Essential for treating newly diagnosed multiple myeloma patients.

BACKGROUND: Multiple myeloma (MM) is known for its immune disturbance and patients suffering from MM are thus vulnerable to opportunistic infections, including herpes zoster (HZ). As HZ infection remarkably affects patients' quality of life and poses huge economic burdens on the health system, we aim to identify the risk factors of HZ infection and evaluate the effects of different dosages, types, and durations of anti-HZ prophylaxis drugs to prevent HZ infection. METHODS: 551 MM patients at Taipei Veterans General Hospital in Taiwan between January 1, 2009 and August 31, 2021 were restrospectively analyzed. The patients' baseline characteristics were recorded. The primary endpoint of the study was the incidence of HZ infection among the studied patient population. Due to the lack of cost coverage from Taiwanese public health insurance on HZ prophylaxis drugs, the use of anti-HZ drugs mainly depends on physicians' preferences and patients' choices. RESULTS: In our study, prophylaxis was given to 283 of the patients. In the multivariate analysis, we included non-prophylaxis, age ≥ 60, corrected serum calcium ≥12 mg/dl, serum creatinine ≥2 mg/dl, serum ß2-microglobulin ≥5500 mg/L, autologous stem cell transplant (SCT), and allogeneic SCT for analysis. Our results demonstrated that the non-prophylaxis group (HR: 2.37, 95% CI 1.57-3.57) and patients receiving autologous SCT (HR: 2.22, 95% CI 1.28-3.86) and allogeneic SCT (HR: 5.12, 95% CI 1.13-23.22) had higher risk of HZ infection. The difference in dosage and types of anti-HZ drugs showed similar protective effects. In patients who stopped anti-HZ prophylaxis before active cancer-related treatment, a higher risk of getting HZ infection compared to the corresponding group was also observed (adjusted HR 3.09, 95% CI 1.35-7.07, p = 0.008). CONCLUSIONS: We concluded that MM patients should receive HZ prophylaxis drugs while receiving active cancer-related treatment. Patients receiving SCT are also at high risk of getting HZ infection, even under prophylaxis.

Surface TREM2 on circulating M-MDSCs as a novel prognostic factor for adults with treatment-naïve diffuse large B-cell lymphoma.

INTRODUCTION: Circulating monocytic myeloid-derived suppressive cells (M-MDSCs) are implicated as a poor prognostic factor and cause CAR T-cell failure in diffuse large B-cell lymphoma (DLBCL). Triggering receptors expressed on myeloid cells 2 (TREM2) are a transmembrane glycoprotein that polarize macrophages to anti-inflammation phenotype but have never been explored on M-MDSCs. This study aims to elucidate the expression and clinical impact of surface TREM2 on circulating M-MDSCs derived from DLBCL adults. METHODS: This prospective, observational study enrolled 100 adults with newly diagnosed and treatment-naïve DLBCL from May 2019 to October 2021. Human circulating M-MDSCs were obtained from freshly isolated peripheral blood, and each patient's surface-TREM2 level on M-MDSCs was normalized via a healthy control at the same performance of flow-cytometry analysis. Murine MDSCs derived from bone marrow (BM-MDSCs) were adopted to assess the link between Trem2 and cytotoxic T lymphocytes. RESULTS: More circulating M-MDSCs at diagnosis of DLBCL predicted worse progression-free (PFS) and overall survival (OS). Patients with higher IPI scores, bone marrow involvement, or lower absolute counts of CD4+ or CD8+ T cells in PB had significantly higher normalized TREM2 levels on M-MDSCs. Additionally, normalized TREM2 levels on M-MDSCs could be grouped into low (< 2%), medium (2-44%), or high (> 44%) levels, and a high normalized TREM2 level on M-MDSCs was proven as an independent prognostic factor for both PFS and OS via multivariate Cox regression analysis and associated with worst PFS and OS. Interestingly, normalized levels of surface TREM2 on M-MDSCs were negatively associated with absolute counts of PB CD8+ T cells and positively correlated with levels of intracellular arginase 1 (ARG1) within M-MDSCs. Wild-type BM-MDSCs had significantly higher mRNA levels of Arg1 and showed more prominent ability to suppress the proliferation of co-cultured CD8+ T cells than BM-MDSCs from Trem2 knockout mice, and the suppressive ability could be impaired by adding Arg1 inhibitors (CB1158) or supplementing L-arginine. CONCLUSION: In treatment-naïve DLBCL adults, a high surface-TREM2 level on circulating M-MDSCs is a poor prognostic factor for both PFS and OS and warrants further investigation for its potential as a novel target in immunotherapy.