Frontiers of Medicine

ISSN 2095-0217

ISSN 2095-0225(Online)

CN 11-5983/R

2018 Impact Factor: 1.847

Cover Story   2023, Volume 17 Issue 4
Cover Figure
The 15 quality control indicators of Chinese ICU constituting the 6 core elements and their weights based on EFA. (Courtesy of Drs. Guangliang Shan, Dawei Liu, and Xiang Zhou. See pages 675-684 by Longxiang Su et al. for more information.)
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, Volume 17 Issue 4

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REVIEW
Immunometabolism: a new dimension in immunotherapy resistance
Chaoyue Xiao, Wei Xiong, Yiting Xu, Ji’an Zou, Yue Zeng, Junqi Liu, Yurong Peng, Chunhong Hu, Fang Wu
Front. Med.. 2023, 17 (4): 585-616.  
https://doi.org/10.1007/s11684-023-1012-z

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Immune checkpoint inhibitors (ICIs) have demonstrated unparalleled clinical responses and revolutionized the paradigm of tumor treatment, while substantial patients remain unresponsive or develop resistance to ICIs as a single agent, which is traceable to cellular metabolic dysfunction. Although dysregulated metabolism has long been adjudged as a hallmark of tumor, it is now increasingly accepted that metabolic reprogramming is not exclusive to tumor cells but is also characteristic of immunocytes. Correspondingly, people used to pay more attention to the effect of tumor cell metabolism on immunocytes, but in practice immunocytes interact intimately with their own metabolic function in a way that has never been realized before during their activation and differentiation, which opens up a whole new frontier called immunometabolism. The metabolic intervention for tumor-infiltrating immunocytes could offer fresh opportunities to break the resistance and ameliorate existing ICI immunotherapy, whose crux might be to ascertain synergistic combinations of metabolic intervention with ICIs to reap synergic benefits and facilitate an adjusted anti-tumor immune response. Herein, we elaborate potential mechanisms underlying immunotherapy resistance from a novel dimension of metabolic reprogramming in diverse tumor-infiltrating immunocytes, and related metabolic intervention in the hope of offering a reference for targeting metabolic vulnerabilities to circumvent immunotherapeutic resistance.

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Heterogeneity of the tumor immune microenvironment and clinical interventions
Zheng Jin, Qin Zhou, Jia-Nan Cheng, Qingzhu Jia, Bo Zhu
Front. Med.. 2023, 17 (4): 617-648.  
https://doi.org/10.1007/s11684-023-1015-9

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The tumor immune microenvironment (TIME) is broadly composed of various immune cells, and its heterogeneity is characterized by both immune cells and stromal cells. During the course of tumor formation and progression and anti-tumor treatment, the composition of the TIME becomes heterogeneous. Such immunological heterogeneity is not only present between populations but also exists on temporal and spatial scales. Owing to the existence of TIME, clinical outcomes can differ when a similar treatment strategy is provided to patients. Therefore, a comprehensive assessment of TIME heterogeneity is essential for developing precise and effective therapies. Facilitated by advanced technologies, it is possible to understand the complexity and diversity of the TIME and its influence on therapy responses. In this review, we discuss the potential reasons for TIME heterogeneity and the current approaches used to explore it. We also summarize clinical intervention strategies based on associated mechanisms or targets to control immunological heterogeneity.

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Minimal residual disease in solid tumors: an overview
Yarui Ma, Jingbo Gan, Yinlei Bai, Dandan Cao, Yuchen Jiao
Front. Med.. 2023, 17 (4): 649-674.  
https://doi.org/10.1007/s11684-023-1018-6

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Minimal residual disease (MRD) is termed as the small numbers of remnant tumor cells in a subset of patients with tumors. Liquid biopsy is increasingly used for the detection of MRD, illustrating the potential of MRD detection to provide more accurate management for cancer patients. As new techniques and algorithms have enhanced the performance of MRD detection, the approach is becoming more widely and routinely used to predict the prognosis and monitor the relapse of cancer patients. In fact, MRD detection has been shown to achieve better performance than imaging methods. On this basis, rigorous investigation of MRD detection as an integral method for guiding clinical treatment has made important advances. This review summarizes the development of MRD biomarkers, techniques, and strategies for the detection of cancer, and emphasizes the application of MRD detection in solid tumors, particularly for the guidance of clinical treatment.

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RESEARCH ARTICLE
Evaluation of ICUs and weight of quality control indicators: an exploratory study based on Chinese ICU quality data from 2015 to 2020
Longxiang Su, Xudong Ma, Sifa Gao, Zhi Yin, Yujie Chen, Wenhu Wang, Huaiwu He, Wei Du, Yaoda Hu, Dandan Ma, Feng Zhang, Wen Zhu, Xiaoyang Meng, Guoqiang Sun, Lian Ma, Huizhen Jiang, Guangliang Shan, Dawei Liu, Xiang Zhou, on behalf of China-NCCQC
Front. Med.. 2023, 17 (4): 675-684.  
https://doi.org/10.1007/s11684-022-0970-x

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This study aimed to explore key quality control factors that affected the prognosis of intensive care unit (ICU) patients in Chinese mainland over six years (2015−2020). The data for this study were from 31 provincial and municipal hospitals (3425 hospital ICUs) and included 2 110 685 ICU patients, for a total of 27 607 376 ICU hospitalization days. We found that 15 initially established quality control indicators were good predictors of patient prognosis, including percentage of ICU patients out of all inpatients (%), percentage of ICU bed occupancy of total inpatient bed occupancy (%), percentage of all ICU inpatients with an APACHE II score ≥15 (%), three-hour (surviving sepsis campaign) SSC bundle compliance (%), six-hour SSC bundle compliance (%), rate of microbe detection before antibiotics (%), percentage of drug deep venous thrombosis (DVT) prophylaxis (%), percentage of unplanned endotracheal extubations (%), percentage of patients reintubated within 48 hours (%), unplanned transfers to the ICU (%), 48-h ICU readmission rate (%), ventilator associated pneumonia (VAP) (per 1000 ventilator days), catheter related blood stream infection (CRBSI) (per 1000 catheter days), catheter-associated urinary tract infections (CAUTI) (per 1000 catheter days), in-hospital mortality (%). When exploratory factor analysis was applied, the 15 indicators were divided into 6 core elements that varied in weight regarding quality evaluation: nosocomial infection management (21.35%), compliance with the Surviving Sepsis Campaign guidelines (17.97%), ICU resources (17.46%), airway management (15.53%), prevention of deep-vein thrombosis (14.07%), and severity of patient condition (13.61%). Based on the different weights of the core elements associated with the 15 indicators, we developed an integrated quality scoring system defined as F score=21.35%×nosocomial infection management + 17.97%×compliance with SSC guidelines + 17.46%×ICU resources + 15.53%×airway management + 14.07%×DVT prevention + 13.61%×severity of patient condition. This evidence-based quality scoring system will help in assessing the key elements of quality management and establish a foundation for further optimization of the quality control indicator system.

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ACSL5, a prognostic factor in acute myeloid leukemia, modulates the activity of Wnt/β-catenin signaling by palmitoylation modification
Wenle Ye, Jinghan Wang, Jiansong Huang, Xiao He, Zhixin Ma, Xia Li, Xin Huang, Fenglin Li, Shujuan Huang, Jiajia Pan, Jingrui Jin, Qing Ling, Yungui Wang, Yongping Yu, Jie Sun, Jie Jin
Front. Med.. 2023, 17 (4): 685-698.  
https://doi.org/10.1007/s11684-022-0942-1

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Acyl-CoA synthetase long chain family member 5 (ACSL5), is a member of the acyl-CoA synthetases (ACSs) family that activates long chain fatty acids by catalyzing the synthesis of fatty acyl-CoAs. The dysregulation of ACSL5 has been reported in some cancers, such as glioma and colon cancers. However, little is known about the role of ACSL5 in acute myeloid leukemia (AML). We found that the expression of ACSL5 was higher in bone marrow cells from AML patients compared with that from healthy donors. ACSL5 level could serve as an independent prognostic predictor of the overall survival of AML patients. In AML cells, the ACSL5 knockdown inhibited cell growth both in vitro and in vivo. Mechanistically, the knockdown of ACSL5 suppressed the activation of the Wnt/β-catenin pathway by suppressing the palmitoylation modification of Wnt3a. Additionally, triacsin c, a pan-ACS family inhibitor, inhibited cell growth and robustly induced cell apoptosis when combined with ABT-199, the FDA approved BCL-2 inhibitor for AML therapy. Our results indicate that ACSL5 is a potential prognosis marker for AML and a promising pharmacological target for the treatment of molecularly stratified AML.

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Immunosuppressive tumor microenvironment contributes to tumor progression in diffuse large B-cell lymphoma upon anti-CD19 chimeric antigen receptor T therapy
Zixun Yan, Li Li, Di Fu, Wen Wu, Niu Qiao, Yaohui Huang, Lu Jiang, Depei Wu, Yu Hu, Huilai Zhang, Pengpeng Xu, Shu Cheng, Li Wang, Sahin Lacin, Muharrem Muftuoglu, Weili Zhao
Front. Med.. 2023, 17 (4): 699-713.  
https://doi.org/10.1007/s11684-022-0972-8

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Anti-CD19 chimeric antigen receptor (CAR)-T cell therapy has achieved 40%–50% long-term complete response in relapsed or refractory diffuse large B-cell lymphoma (DLBCL) patients. However, the underlying mechanism of alterations in the tumor microenvironments resulting in CAR-T cell therapy failure needs further investigation. A multi-center phase I/II trial of anti-CD19 CD28z CAR-T (FKC876, ChiCTR1800019661) was conducted. Among 22 evaluable DLBCL patients, seven achieved complete remission, 10 experienced partial remissions, while four had stable disease by day 29. Single-cell RNA sequencing results were obtained from core needle biopsy tumor samples collected from long-term complete remission and early-progressed patients, and compared at different stages of treatment. M2-subtype macrophages were significantly involved in both in vivo and in vitro anti-tumor functions of CAR-T cells, leading to CAR-T cell therapy failure and disease progression in DLBCL. Immunosuppressive tumor microenvironments persisted before CAR-T cell therapy, during both cell expansion and disease progression, which could not be altered by infiltrating CAR-T cells. Aberrant metabolism profile of M2-subtype macrophages and those of dysfunctional T cells also contributed to the immunosuppressive tumor microenvironments. Thus, our findings provided a clinical rationale for targeting tumor microenvironments and reprogramming immune cell metabolism as effective therapeutic strategies to prevent lymphoma relapse in future designs of CAR-T cell therapy.

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FERM domain-containing protein FRMD6 activates the mTOR signaling pathway and promotes lung cancer progression
Tianzhuo Wang, Huiying Guo, Lei Zhang, Miao Yu, Qianchen Li, Jing Zhang, Yan Tang, Hongquan Zhang, Jun Zhan
Front. Med.. 2023, 17 (4): 714-728.  
https://doi.org/10.1007/s11684-022-0959-5

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FRMD6, a member of the 4.1 ezrin–radixin–moesin domain-containing protein family, has been reported to inhibit tumor progression in multiple cancers. Here, we demonstrate the involvement of FRMD6 in lung cancer progression. We find that FRMD6 is overexpressed in lung cancer tissues relative to in normal lung tissues. In addition, the enhanced expression of FRMD6 is associated with poor outcomes in patients with lung squamous cell carcinoma (n = 75, P = 0.0054) and lung adenocarcinoma (n = 94, P = 0.0330). Cell migration and proliferation in vitro and tumor formation in vivo are promoted by FRMD6 but are suppressed by the depletion of FRMD6. Mechanistically, FRMD6 interacts and colocalizes with mTOR and S6K, which are the key molecules of the mTOR signaling pathway. FRMD6 markedly enhances the interaction between mTOR and S6K, subsequently increasing the levels of endogenous pS6K and downstream pS6 in lung cancer cells. Furthermore, knocking out FRMD6 inhibits the activation of the mTOR signaling pathway in Frmd6−/− gene KO MEFs and mice. Altogether, our results show that FRMD6 contributes to lung cancer progression by activating the mTOR signaling pathway.

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Dihydroartemisinin increased the abundance of Akkermansia muciniphila by YAP1 depression that sensitizes hepatocellular carcinoma to anti-PD-1 immunotherapy
Zhiqin Zhang, Xinli Shi, Jingmin Ji, Yinglin Guo, Qing Peng, Liyuan Hao, Yu Xue, Yiwei Liu, Caige Li, Junlan Lu, Kun Yu
Front. Med.. 2023, 17 (4): 729-746.  
https://doi.org/10.1007/s11684-022-0978-2

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The effect of anti-programmed cell death 1 (anti-PD-1) immunotherapy is limited in patients with hepatocellular carcinoma (HCC). Yes-associated protein 1 (YAP1) expression increased in liver tumor cells in early HCC, and Akkermansia muciniphila abundance decreased in the colon. The response to anti-PD-1 treatment is associated with A. muciniphila abundance in many tumors. However, the interaction between A. muciniphila abundance and YAP1 expression remains unclear in HCC. Here, anti-PD-1 treatment decreased A. muciniphila abundance in the colon, but increased YAP1 expression in the tumor cells by mice with liver tumors in situ. Mechanistically, hepatocyte-specific Yap1 knockout (Yap1LKO) maintained bile acid homeostasis in the liver, resulting in an increased abundance of A. muciniphila in the colon. Yap1 knockout enhanced anti-PD-1 efficacy. Therefore, YAP1 inhibition is a potential target for increasing A. muciniphila abundance to promote anti-PD-1 efficacy in liver tumors. Dihydroartemisinin (DHA), acting as YAP1 inhibitor, increased A. muciniphila abundance to sensitize anti-PD-1 therapy. A. muciniphila by gavage increased the number and activation of CD8+ T cells in liver tumor niches during DHA treatment or combination with anti-PD-1. Our findings suggested that the combination anti-PD-1 with DHA is an effective strategy for liver tumor treatment.

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Neutralization against SARS-CoV-2 Delta/Omicron variants and B cell response after inactivated vaccination among COVID-19 convalescents
Hao Wang, Yu Yuan, Bihao Wu, Mingzhong Xiao, Zhen Wang, Tingyue Diao, Rui Zeng, Li Chen, Yanshou Lei, Pinpin Long, Yi Guo, Xuefeng Lai, Yuying Wen, Wenhui Li, Hao Cai, Lulu Song, Wei Ni, Youyun Zhao, Kani Ouyang, Jingzhi Wang, Qi Wang, Li Liu, Chaolong Wang, An Pan, Xiaodong Li, Rui Gong, Tangchun Wu
Front. Med.. 2023, 17 (4): 747-757.  
https://doi.org/10.1007/s11684-022-0954-x

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Emerging SARS-CoV-2 variants have made COVID-19 convalescents susceptible to re-infection and have raised concern about the efficacy of inactivated vaccination in neutralization against emerging variants and antigen-specific B cell response. To this end, a study on a long-term cohort of 208 participants who have recovered from COVID-19 was conducted, and the participants were followed up at 3.3 (Visit 1), 9.2 (Visit 2), and 18.5 (Visit 3) months after SARS-CoV-2 infection. They were classified into three groups (no-vaccination (n = 54), one-dose (n = 62), and two-dose (n = 92) groups) on the basis of the administration of inactivated vaccination. The neutralizing antibody (NAb) titers against the wild-type virus continued to decrease in the no-vaccination group, but they rose significantly in the one-dose and two-dose groups, with the highest NAb titers being observed in the two-dose group at Visit 3. The NAb titers against the Delta variant for the no-vaccination, one-dose, and two-dose groups decreased by 3.3, 1.9, and 2.3 folds relative to the wild-type virus, respectively, and those against the Omicron variant decreased by 7.0, 4.0, and 3.8 folds, respectively. Similarly, the responses of SARS-CoV-2 RBD-specific B cells and memory B cells were boosted by the second vaccine dose. Results showed that the convalescents benefited from the administration of the inactivated vaccine (one or two doses), which enhanced neutralization against highly mutated SARS-CoV-2 variants and memory B cell responses. Two doses of inactivated vaccine among COVID-19 convalescents are therefore recommended for the prevention of the COVID-19 pandemic, and vaccination guidelines and policies need to be updated.

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Primary assessment of the diversity of Omicron sublineages and the epidemiologic features of autumn/winter 2022 COVID-19 wave in Chinese mainland
Gang Lu, Yun Ling, Minghao Jiang, Yun Tan, Dong Wei, Lu Jiang, Shuting Yu, Fangying Jiang, Shuai Wang, Yao Dai, Jinzeng Wang, Geng Wu, Xinxin Zhang, Guoyu Meng, Shengyue Wang, Feng Liu, Xiaohong Fan, Saijuan Chen
Front. Med.. 2023, 17 (4): 758-767.  
https://doi.org/10.1007/s11684-022-0981-7

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With the recent ongoing autumn/winter 2022 COVID-19 wave and the adjustment of public health control measures, there have been widespread SARS-CoV-2 infections in Chinese mainland. Here we have analyzed 369 viral genomes from recently diagnosed COVID-19 patients in Shanghai, identifying a large number of sublineages of the SARS-CoV-2 Omicron family. Phylogenetic analysis, coupled with contact history tracing, revealed simultaneous community transmission of two Omicron sublineages dominating the infections in some areas of China (BA.5.2 mainly in Guangzhou and Shanghai, and BF.7 mainly in Beijing) and two highly infectious sublineages recently imported from abroad (XBB and BQ.1). Publicly available data from August 31 to November 29, 2022 indicated an overall severe/critical case rate of 0.035% nationwide, while analysis of 5706 symptomatic patients treated at the Shanghai Public Health Center between September 1 and December 26, 2022 showed that 20 cases (0.35%) without comorbidities progressed into severe/critical conditions and 153 cases (2.68%) with COVID-19-exacerbated comorbidities progressed into severe/critical conditions. These observations shall alert healthcare providers to place more resources for the treatment of severe/critical cases. Furthermore, mathematical modeling predicts this autumn/winter wave might pass through major cities in China by the end of the year, whereas some middle and western provinces and rural areas would be hit by the upcoming infection wave in mid-to-late January 2023, and the duration and magnitude of upcoming outbreak could be dramatically enhanced by the extensive travels during the Spring Festival (January 21, 2023). Altogether, these preliminary data highlight the needs to allocate resources to early diagnosis and effective treatment of severe cases and the protection of vulnerable population, especially in the rural areas, to ensure the country’s smooth exit from the ongoing pandemic and accelerate socio-economic recovery.

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Machine learning modeling identifies hypertrophic cardiomyopathy subtypes with genetic signature
Jiaqi Dai, Tao Wang, Ke Xu, Yang Sun, Zongzhe Li, Peng Chen, Hong Wang, Dongyang Wu, Yanghui Chen, Lei Xiao, Hao Liu, Haoran Wei, Rui Li, Liyuan Peng, Ting Yu, Yan Wang, Zhongsheng Sun, Dao Wen Wang
Front. Med.. 2023, 17 (4): 768-780.  
https://doi.org/10.1007/s11684-023-0982-1

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Previous studies have revealed that patients with hypertrophic cardiomyopathy (HCM) exhibit differences in symptom severity and prognosis, indicating potential HCM subtypes among these patients. Here, 793 patients with HCM were recruited at an average follow-up of 32.78 ± 27.58 months to identify potential HCM subtypes by performing consensus clustering on the basis of their echocardiography features. Furthermore, we proposed a systematic method for illustrating the relationship between the phenotype and genotype of each HCM subtype by using machine learning modeling and interactome network detection techniques based on whole-exome sequencing data. Another independent cohort that consisted of 414 patients with HCM was recruited to replicate the findings. Consequently, two subtypes characterized by different clinical outcomes were identified in HCM. Patients with subtype 2 presented asymmetric septal hypertrophy associated with a stable course, while those with subtype 1 displayed left ventricular systolic dysfunction and aggressive progression. Machine learning modeling based on personal whole-exome data identified 46 genes with mutation burden that could accurately predict subtype propensities. Furthermore, the patients in another cohort predicted as subtype 1 by the 46-gene model presented increased left ventricular end-diastolic diameter and reduced left ventricular ejection fraction. By employing echocardiography and genetic screening for the 46 genes, HCM can be classified into two subtypes with distinct clinical outcomes.

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Hyperosmolarity promotes macrophage pyroptosis by driving the glycolytic reprogramming of corneal epithelial cells in dry eye disease
Yu Han, Yu Zhang, Kelan Yuan, Yaying Wu, Xiuming Jin, Xiaodan Huang
Front. Med.. 2023, 17 (4): 781-795.  
https://doi.org/10.1007/s11684-023-0986-x

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Tear film hyperosmolarity plays a core role in the development of dry eye disease (DED) by mediating the disruption of ocular surface homeostasis and triggering inflammation in ocular surface epithelium. In this study, the mechanisms involving the hyperosmolar microenvironment, glycolysis mediating metabolic reprogramming, and pyroptosis were explored clinically, in vitro, and in vivo. Data from DED clinical samples indicated that the expression of glycolysis and pyroptosis-related genes, including PKM2 and GSDMD, was significantly upregulated and that the secretion of IL-1β significantly increased. In vitro, the indirect coculture of macrophages derived from THP-1 and human corneal epithelial cells (HCECs) was used to discuss the interaction among cells. The hyperosmolar environment was found to greatly induce HCECs’ metabolic reprogramming, which may be the primary cause of the subsequent inflammation in macrophages upon the activation of the related gene and protein expression. 2-Deoxy-d-glucose (2-DG) could inhibit the glycolysis of HCECs and subsequently suppress the pyroptosis of macrophages. In vivo, 2-DG showed potential efficacy in relieving DED activity and could significantly reduce the overexpression of genes and proteins related to glycolysis and pyroptosis. In summary, our findings suggested that hyperosmolar-induced glycolytic reprogramming played an active role in promoting DED inflammation by mediating pyroptosis.

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PERSPECTIVE
The nature of cancer
Min Yan, Quentin Liu
Front. Med.. 2023, 17 (4): 796-803.  
https://doi.org/10.1007/s11684-022-0975-5

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13 articles