Tumor extracellular vesicle-derived PD-L1 promotes T cell senescence through lipid metabolism reprogramming

T cell aging and exhaustion: Mechanisms and clinical implications

T cell senescence and exhaustion represent critical aspects of adaptive immune system dysfunction, with profound implications for health and the development of disease prevention and therapeutic strategies. These processes, though distinct, are interconnected at the molecular level, leading to impaired effector functions and reduced proliferative capacity of T cells. Such impairments increase susceptibility to diseases and diminish the efficacy of vaccines and treatments. Importantly, T cell senescence and exhaustion can dynamically influence each other, particularly in the context of chronic diseases. A deeper understanding of the molecular mechanisms underlying T cell senescence and exhaustion, as well as their interplay, is essential for elucidating the pathogenesis of related diseases and restoring dysfunctional immune responses. This knowledge will pave the way for the development of targeted therapeutic interventions and strategies to enhance immune competence. This review aims to summarize the characteristics, mechanisms, and disease associations of T cell senescence and exhaustion, while also delineating the distinctions and intersections between these two states to enhance our comprehension.

Exosomal dynamics: Bridging the gap between cellular senescence and cancer therapy

Cancer remains one of the most devastating diseases, severely affecting public health and contributing to economic instability. Researchers worldwide are dedicated to developing effective therapeutics to target cancer cells. One promising strategy involves inducing cellular senescence, a complex state in which cells exit the cell cycle. Senescence has profound effects on both physiological and pathological processes, influencing cellular systems through secreted factors that affect surrounding and distant cells. Among these factors are exosomes, small extracellular vesicles that play crucial roles in cellular communication, development, and defense, and can contribute to pathological conditions. Recently, there has been increasing interest in engineering exosomes as precise drug delivery vehicles, capable of targeting specific cells or intracellular components. Studies have emphasized the significant role of exosomes from senescent cells in cancer progression and therapy. Notably, chemotherapeutic agents can alter the tumor microenvironment, induce senescence, and trigger immune responses through exosome-mediated cargo transfer. This review explores the intricate relationship between cellular senescence, exosomes, and cancer, examining how different therapeutics can eliminate cancer cells or promote drug resistance. It also investigates the molecular mechanisms and signaling pathways driving these processes, highlighting current challenges and proposing future perspectives to uncover new therapeutic strategies for cancer treatment.

Integrated Bioinformatics Analysis and Cellular Experimental Validation Identify Lipoprotein Lipase Gene as a Novel Biomarker for Tumorigenesis and Prognosis in Lung Adenocarcinoma

Lung adenocarcinoma (LUAD) is one of the leading causes of death worldwide, and thus, more biomarker and therapeutic targets need to be explored. Herein, we aimed to explore new biomarkers of LUAD by integrating bioinformatics analysis with cell experiments. We firstly identified 266 druggable genes that were significantly differentially expressed between LUAD tissues and adjacent normal lung tissues. Among these genes, SMR analysis with p-value correction suggested that declining lipoprotein lipase (LPL) levels may be causally associated with an elevated risk of LUAD, which was corroborated by co-localization analysis. Analyses of clinical data showed that LPL in lung cancer tissues has considerable diagnostic value for LUAD, and elevated LPL levels were positively associated with improved patient survival outcomes. Cell experiments with an LPL activator proved these findings; the activator inhibited the proliferation and migration of lung cancer cells. Next, we found that LPL promoted the infiltration of immune cells such as DCs, IDCs, and macrophages in LUAD by mononuclear sequencing analysis and TIMER2.0. Meanwhile, patients with low levels of LPL expression demonstrated superior immunotherapeutic responses to anti-PD-1 therapy. We conclude that LPL acts as a diagnostic and prognostic marker for LUAD.

Affinity Modifications of Porous Microscaffolds Impact Bone Regeneration by Modulating the Delivery Kinetics of Small Extracellular Vesicles

Biomaterials functionalized with small extracellular vesicles (sEVs) hold great regenerative potential, and their therapeutic efficacy hinges on the delivery kinetics of the sEVs. Achieving rapid and stable loading, along with precisely controlled release of sEVs, necessitates affinity modifications of biomaterials. Here, we provide a quantitative description of the interaction between sEVs and various affinity molecules (i.e., polydopamine (PDA), tannic acid (TA), heparin, polyethylenimine (PEI), and calcium phosphate (CaP)) through molecular dynamics simulation. The interaction strengths followed the order of PDA < heparin < TA < CaP < PEI. To tailor the delivery kinetics of stem cells from human exfoliated deciduous teeth (SHED)-derived sEVs with concentration-dependent bioactivities, we employed two representative affinity molecules, namely PDA and CaP, to modify PLGA porous microscaffolds (PLGA MS), resulting in PDA-modified PLGA MS (PDA@MS) and biomineralized PDA-modified PLGA MS (B/PDA@MS). The B/PDA@MS exhibited the highest loading efficiency (>20 μg/mg microscaffolds) and optimized the release profile of sEVs over 21 days. Upon injection into a 5 mm defect in the rat cranial bone, sEV-loaded B/PDA@MS demonstrated the highest level of bone regeneration, with the new bone volume fraction (BV/TV) and bone mineral density (BMD) reaching 64.0% and 604.5 mg/cm3 within 8 weeks, respectively. This work not only presents a biomineralized microscaffold with sustained sEVs release and high osteogenic potential but also offers guidance on the further design and translation of sEV-functionalized biomaterials with broader applications.

Glycolytic enzyme PFKFB4 governs lipolysis by promoting de novo lipogenesis to drive the progression of hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is among the most aggressive malignancies, marked by high recurrence rates and limited treatment efficacy, especially in HBV-associated HCC (HBV-HCC). This subtype exhibits pronounced metabolic reprogramming, with lipid synthesis playing a pivotal role in driving tumor aggressiveness and therapeutic resistance. However, the molecular mechanisms underlying this metabolic shift remain unclear. In our study, analysis of the LIHC-TCGA database and comparisons between HCC tissues and adjacent peri-tumoral tissues revealed that 6-Phosphofructo-2-Kinase/Fructose-2,6-Biphosphatase 4 (PFKFB4) is significantly upregulated in HBV-HCC. Moreover, elevated PFKFB4 expression correlates with poorer prognosis and unfavorable overall survival among HBV-HCC patients. Functional assays demonstrated that PFKFB4 promotes HCC proliferation by enhancing glycolysis and de novo lipid synthesis. Notably, PFKFB4 not only increases glycolytic flux but also upregulates sterol regulatory element-binding protein 1 (SREBP1) expression via its enzymatic activity. Mechanistically, PFKFB4 suppresses phosphorylated AMP-activated protein kinase (p-AMPK) through enhanced aerobic glycolysis, which in turn stimulates the level of SREBP1. Collectively, these findings position PFKFB4 as a critical mediator of metabolic reprogramming in HBV-HCC and a promising therapeutic target.