Jie Wu

Background: Acute allograft rejection is largely dependent on T cell‐driven immune responses; however, the molecular programs that establish and maintain effector T cell states during rejection remain incompletely defined. Methods: Single‐cell transcriptomic analysis was conducted to characterize the activation of signalling pathways in T cells during acute allograft rejection. The function of MEK1/2 signalling was evaluated both in vitro and in vivo using mice with targeted deletion of Mek1/2 in T cells and pharmacological inhibition. Phosphoproteomic analysis, immunofluorescence staining, and western blotting were conducted to investigate downstream signalling mechanisms, particularly those involving SMAD4. Results: Effector CD4 and CD8 T cells exhibited enhanced MEK/ERK pathway activation throughout the rejection process. MEK1/2 inhibition, either via genetic deletion or pharmacological blockade, attenuated T cell activation and effector activity, leading to reduced rejection and prolonged graft survival. Phosphoproteomic analysis identified SMAD4 as a key downstream effector of MEK1/2 signalling. Mechanistically, MEK1/2 deficiency reduced SMAD4 nuclear translocation in activated T cells, accompanied by diminished effector T cell responses. Conclusions: MEK1/2 signalling regulates T cell activation and effector phenotypes via SMAD4 nuclear translocation in heart transplant rejection. Therapeutic intervention targeting this pathway may contribute to alloimmune response regulation and improve transplant outcomes.

Cardiac allograft vasculopathy (CAV) is the primary impairment that influences the long-term prognosis of transplanted hearts. CAV is characterized by diffuse intimal hyperplasia of the coronary arteries, which is mediated by chronic inflammation, the alloimmune response, and vascular remodeling. Current immunosuppressive regimens effectively control acute rejection but have limited efficacy in preventing CAV and are associated with significant adverse effects upon long-term use. Regulatory T cells (Tregs) are essential for preserving immunological homeostasis and facilitating transplantation tolerance. They are pivotal in suppressing the activation of effector T cells (Teffs), modulating local inflammation, and postponing the progression of CAV. This review comprehensively elucidates the pathophysiology of and diagnostic advancements in CAV, emphasizes the phenotypic heterogeneity, immunosuppressive mechanisms, and protective role of Tregs in heart transplantation, and thoroughly discuss the interplay of PD-1/PD-L1, IL-33, IL-6, CTLA-4, fatty acid oxidation (FAO), and other signaling pathways in modulating Treg function and CAV pathogenesis. In terms of the translational medicine, the adoptive infusion of in vitro -expanded autologous Tregs has demonstrated the ability to postpone CAV in preclinical models; nonetheless, its clinical use is limited by cell stability, challenging preparation processes, and the lack of efficacy biomarkers. Therefore, this review seeks to establish a theoretical foundation and research viewpoint to comprehensively understand the immunological mechanisms of CAV and the advancement of novel Treg-targeted therapies.

Myocardial infarction, characterized by irreversible cardiomyocyte loss, progressive cardiac fibrosis and subsequent deteriorated heart function, constitute an intractable global health burden. Promoting endogenous cardiomyocyte proliferation to achieve functional cardiac regeneration represents an available foreground for combatting heart failure. Based on extensive preclinical evidence, researchers have characterized the cellular and molecular mechanisms governing cardiomyocyte proliferation and elucidated the modulatory influence of the metabolic factors and extracellular matrix. Insights from various studies have facilitated the development of regenerative approaches that reprogramming terminally differentiated cardiomyocytes toward a more metabolic plastic and fetal-like state, thereby enhancing the proliferative and reparative potential. Integration of metabolic and mechanical signals has emerged as a critical determinant of successful cardiomyocyte reactivation, providing a mechanistic rationale for combinatorial therapeutic strategies. Nevertheless, despite remarkable progression in mechanistic understanding and proof-of-concept studies, cardiac regeneration protocols advanced to robust clinical validation or pharmacal application have yet to be developed. This review provides a historical and biologically grounded synthesis of preclinical advances in cardiac repair, regeneration and cardiomyocyte reprogramming, with particular emphasis on translational feasibility and clinical applicability. Current strategies and preclinical trial outcomes are summarized to construct a readiness framework that maps the developmental maturity of each approach. Finally, the review highlights existing biological and technical barriers, as well as emerging opportunities poised to shape the future of cardiac regenerative medicine.

Background: One of the most significant recent advancements in cancer immunotherapy is the development of chimeric antigen receptor (CAR) technology. More recently, this approach has been gradually modified for the research associated with various treatment-resistant nonneoplastic diseases by engineering immune cells to provide precise targeting. Results: This narrative review discusses two primary therapeutic approaches the use of CAR technology in the treatment of nonneoplastic diseases. One strategy involves the elimination of specific pathogenic cell populations. Specifically, by engineering T cells, macrophages, or natural killer (NK) cells, pathogenic cells can be eliminated in autoimmune disorders, infectious diseases, and fibrotic lesions. The second approach aims to restore immune homeostasis by using engineered regulatory T cells (Tregs) to control augmented immune effector responses. This strategy has been shown to promote transplant tolerance and has therapeutic potential for inflammatory bowel disease and type 1 diabetes. Furthermore, this review addresses major issues concerning the persistence, safety, and manufacturing accessibility of CAR cells and discusses some emerging technological approaches that could be used for focused refinements of this technology. Conclusions: The precision medicine platform for CAR technology has advanced beyond oncology by integrating targeted cell destruction with the management of immune homeostasis. As future possibilities with frontier cell engineering and interdisciplinary approaches are explored, CAR cell therapy is likely to evolve into a more adaptable, refined, and clinically viable immunotherapy technology, with its therapeutic potential expanded to a broad range of diseases.

BACKGROUND: Aortic valve calcification increases leaflet stiffness and contributes to the development of calcific aortic valve disease. The molecular and cellular mechanisms underlying calcification remain unclear. Here, we aimed to investigate the role of PRMT3 (protein arginine methyltransferase 3) in valvular calcification and calcific aortic valve disease progression. METHODS: Both aortic valve leaflets and valvular interstitial cells from patients were used to evaluate the expression pattern and investigate the underlying mechanism of PRMT3 in calcific aortic valve disease pathogenesis. High-cholesterol diet–fed Apoe (apolipoprotein E)–deficient ( ApoE ^−/− ) mice with Prmt3 haploinsufficiency were used to examine the role of PRMT3 in aortic valve calcification. The effects of PRMT3 inhibition (SGC707) and degradation (PROTAC compound 11) on aortic valve calcification were investigated in vivo. To elucidate the mechanisms underlying the procalcific effects of PRMT3, we performed immunoprecipitation coupled with liquid chromatography–tandem mass spectrometry and coimmunoprecipitation assays with an enzymatically inactive PRMT3 variant as well as arginine-to-lysine and lysine-to-alanine substitution PCSK9 variants. RESULTS: We found that PRMT3 expression was significantly upregulated during aortic valve calcification. RUNX2 (runt-related transcription factor 2) recruited P300 to promote PRMT3 expression through histone H3 lysine 27 acetylation. Moreover, Prmt3 haploinsufficiency markedly ameliorated aortic valve calcification in high-cholesterol diet–fed ApoE ^−/− mice, as revealed by reduced thickness and calcium deposition in the aortic valve leaflets, improved echocardiographic measures (decreased peak transvalvular jet velocity, reduced mean transvalvular pressure gradient, and increased aortic valve area), and decreased levels of osteogenic markers OPN (osteopontin) and Osx (Osterix) in the aortic valve leaflets. In addition, anticalcific effects were achieved through pharmacologic PRMT3 inhibition with SGC707 and PRMT3 degradation through PROTAC. Consistent with the in vivo results, we found that PRMT3 promoted the osteogenic differentiation of human valvular interstitial cells through its enzymatic activity. Mechanistically, we revealed that PRMT3 catalyzed the asymmetric dimethylation of PCSK9 at the arginine 582 residue (R582), which was accompanied by a prolonged PCSK9 half-life. This methylation prevented the binding of the E3 ligase CHIP (carboxyl terminus of Hsc70-interacting protein) to PCSK9 at lysine 575 (K575), thereby abrogating ubiquitination-mediated degradation of PCSK9, which is a procalcific factor, and accelerating aortic valve calcification progression. CONCLUSIONS: We identify a previously unrecognized posttranslational mechanism regulating PCSK9 stability in valve interstitial cells during calcific aortic valve disease and establish a link between PRMT3-mediated arginine methylation and valve-specific lipid–osteogenic coupling.

Background: Emerging evidence has underscored the significance of antitumor humoral immunity, which is associated with the development of T follicular helper (Tfh) cell. However, the molecular mechanisms underlying Tfh differentiation in antitumor immunity remains poorly understood. Methods: We analyzed publicly available RNA-seq data across various representative immune models to identify signature pathways of Tfh cells. Subsequently, we generated T-cell-specific Mek 1/2 knockout mice and investigated the functional phenotypes through Tfh cell polarization, adoptive transfer, and flow cytometry assays. Next, we employed multi-omics sequencing and overexpression experiments to delineate the underlying mechanisms of cellular phenotypes. Finally, by integrated analysis of scRNA-seq datasets combined with MEK inhibitor intervention studies, we elucidated the anti-tumor humoral responses of MEK inhibitors in both murine tumor models and TCGA-SKCM patient cohort. Results: Mitogen-activated protein kinase kinase 1/2 (MEK1/2) signaling was identified as a potential regulator of Tfh cells and antitumor humoral response. Codeletion or pharmacological inhibition of MEK1/2 effectively promoted Tfh cell development in vitro and in vivo. Mechanistically, ATAC-seq and RNA-seq integrative analysis revealed interferon regulatory factor 4 (IRF4)-dependent epigenetic modulation of characteristic Tfh cell genes, thereby driving Tfh differentiation. Overexpression of Irf4 counteracted Mek 1/2 ablation-mediated Tfh cell generation. Moreover, MEK1/2 inhibitor therapy enhanced Tfh infiltration coupled with humoral immune responses in murine melanoma model and was correlated with favorable clinical prognosis in melanoma patients. Conclusions: Our study revealed the MEK1/2-IRF4 axis potentiates Tfh development to enhance the antitumor humoral response. These findings may provide an unprecedented strategy to improve antitumor immunotherapy efficacy by harnessing humoral immune responses.

Cytotoxic CD4 ⁺ T lymphocytes are a unique subset of CD4 ⁺ T cells characterized by their cytokine secretion and cytolytic activity. Unlike traditional CD4 ⁺ helper T cells, cytotoxic CD4 ⁺ T lymphocytes exhibit similar cytotoxicity to that of CD8 ⁺ T cells, revealing unexpected plasticity in CD4 ⁺ T-cell functions. This flexibility suggests that CD4 ⁺ T cells can transform and acquire effector functions beyond their conventional functions, emphasizing their importance in various immune responses. Despite the identification of cytotoxic CD4 ⁺ T lymphocytes decades ago, recent advancements have broadened our understanding of their phenotypic diversity, transcriptional regulation, differentiation pathways, and functional roles. Cytotoxic CD4 ⁺ T lymphocytes play pivotal roles across a broad spectrum of diseases, including cancer, infectious diseases, autoimmune disorders, and cardiovascular diseases. They typically mediate strong inflammatory responses and kill target cells through cytotoxicity, playing a crucial role in maintaining immune homeostasis. In this review, we synthesize current findings on cytotoxic CD4 ⁺ T lymphocytes, emphasizing their origin, biomarkers, regulatory molecules, and biological functions. Additionally, we focus on their pathological roles in the progression of various diseases and examine how cytotoxic CD4 ⁺ T lymphocytes contribute to disease development and progression. We also provide a comprehensive summary of therapeutic strategies targeting cytotoxic CD4 ⁺ T cells and review the associated clinical trial data, aiming to propose new strategies for disease management through the targeting of cytotoxic CD4 ⁺ T lymphocytes.

Background: Surgical strategies for congenital aortic stenosis and regurgitation in children, particularly in infants (p < 0.001), and the median peak velocity decreased from 4.1 m/s to 2.9 m/s ( p < 0.001), postoperatively. No new moderate or severe aortic regurgitation was observed early postoperatively, and preexisting lesions of this severity were resolved. There were no in-hospital deaths or severe complications. At four years, survival was 96% and freedom from reoperation 75.4% in the overall cohort; in infants, survival was 100% with 66.7% freedom from reoperation. Conclusions: AVP with pericardium patch is a safe and effective procedure for congenital aortic stenosis and regurgitation in pediatric patients. It represents a promising surgical option for pediatric patients, including infants.