EP2/EP4 targeting prevents tumor-derived PGE2-mediated immunosuppression in cDC2s

Inhibition of PDT-induced PGE2 surge for enhanced photo-immunotherapy

Nowadays, photodynamic therapy (PDT) offers a non-invasive tumor treatment with high safety profiles and minimal side effects, implying a promising clinical application for patients with malignant tumors. However, the lack of efficacy in metastasis and recurrence still notably limits its application. To solve this problem, one promising strategy is to improve the immune response activated by PDT. Unfortunately, tumor cells derived PGE2 could create immunosuppressive microenvironments and impair the function of multiple immune cells, leading to a failure of immune system activation. Moreover, our research revealed the up-regulation of Ptgs2 in tumor cells after the PDT process, which is associated with a series of pro-tumor effects, including proliferation, invasion, metastasis, apoptotic resistance, and immune evasion. Consequently, controlling the PGE2 surge induced by PDT is crucial for optimizing the efficacy of photo-immunotherapy. Therefore, we combined the regulation of the COX2-PGE2 axis with PDT. The addition of COX inhibitors (COX-Is) could improve the efficiency of PDT, reduce the immunosuppressive effect of PGE2, and help dying tumor cells activate the immune system. Herein, a tumor-targeted nano-delivery platform (FI@T-Lipo) was developed using advanced microfluidic technology. FI@T-Lipo based PDT showed a systemic therapeutic effect in triple negative breast cancer through reclaiming the anti-tumor effect of the immune system under COX2-PGE2 blockage. In a word, we developed an in-situ tumor vaccination strategy based on COX-Is enhanced PDT, which could alleviate intra-tumoral immune suppression and boost immune system activation. Our study offers a promising modality for advancing clinical treatment strategies for metastatic malignant tumors.

Prostaglandin E2 receptor EP4 activation induces tolerogenic dendritic cells to mitigate ischemic acute kidney injury

The prevalence and mortality rates of acute kidney injury (AKI) remain high, with ischemia-reperfusion (I/R) being a major cause in clinical settings. Dendritic cells (DCs) play a crucial role in inducing the infiltration of inflammatory cells into the kidneys during I/R, leading to persistent kidney damage. However, immature DCs (imDCs) maintain self-tolerance under homeostatic conditions. Therefore, targeting the immunomodulatory duality of DCs to prevent I/R-AKI is of significant importance. In this study, we found Pre-treatment of bone marrow-derived dendritic cells (BMDCs) with the EP4 receptor agonist L-902,688 induced the generation of EP4highCCR7high DC (LDC), However, there was a decrease in its maturation markers (CD80, CD86, and MHCII). Additionally, treatment with the EP4 receptor antagonist GW 627,368 resulted in reduced CCR7 expression on DCs without significantly affecting DC maturation. Furthermore, levels of pro-inflammatory cytokines decreased in the supernatant of LDCs while secretion of the anti-inflammatory cytokine IL-10 surged, indicating that LDCs possess stronger immune tolerance. Subsequent co-culturing mouse renal tubular epithelial cells TCMK-1 with LDCs did not impair TCMK-1 cells viability but rather enhanced cell migration rates. Following hypoxia-reoxygenation (H/R) treatment, TCMK-1 cells co-cultured with LDCs exhibited reduced intracellular ROS levels, improved oxidative stress response, reduced apoptosis, and preserved migratory capacity. In addition, our in vivo pharmacological intervention experiments manifested that the preemptive activation of the EP4 receptor conferred remarkable renal protection by inhibiting renal DC maturation. Collectively, our findings further investigate the involvement of PGE2-EP4 signaling in the regulation of DC immune function, emphasizing the potential benefits of targeting the PGE2-EP4-DC axis for preventing I/R-AKI.

Tumor-derived vesicles in immune modulation: focus on signaling pathways

Tumor-derived extracellular vesicles (TDEVs) represent a heterogeneous population of extracellular vesicles (EVs), including exosomes, microvesicles, and apoptotic bodies, which are essential for tumor growth. EVs function as natural carriers of bioactive molecules, including lipids, proteins, and nucleic acids, enabling them to influence and regulate complex cellular interactions within the tumor microenvironment (TME). The TDEVs mainly have immunosuppressive functions as a result of the inhibitory signals disrupting the immune cell anti-tumor activity. They enhance tumor progression and immune evasion by inhibiting the effector function of immune cells and by altering critical processes of immune cell recruitment, polarization, and functional suppression by different signaling pathways. In this sense, TDEVs modulate the NF-κB pathway, promoting inflammation and inducing immune evasion. The Janus kinase (JAK)-signal transducer and activator of transcription (STAT) signaling is required for TDEV-mediated immune suppression and the manifestation of tumor-supporting features. The phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) signaling, necessary for metabolic reprogramming, is orchestrated by TDEV to abrogate immune response and drive cancer cell proliferation. Finally, exosomal cargo can modulate the NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome, activating pro-inflammatory responses that influence tumor development and immunomodulation. In this review, we take a deep dive into how TDEVs affect the immune cells by altering key signaling pathways. We also examine emerging therapeutic approaches aimed at disrupting EV-mediated pathways, offering promising avenues for the development of novel EV-based cancer immunotherapy.

Tumor secretome shapes the immune landscape during cancer progression

The focus of cancer immunotherapy has traditionally been on immune cells and tumor cells themselves, often overlooking the tumor secretome. This review provides a comprehensive overview of the intricate relationship between tumor cells and the immune response in cancer progression. It highlights the pivotal role of the tumor secretome - a diverse set of molecules secreted by tumor cells - in significantly influencing immune modulation, promoting immunosuppression, and facilitating tumor survival. In addition to elucidating these complex interactions, this review discusses current clinical trials targeting the tumor secretome and highlights their potential to advance personalized medicine strategies. These trials aim to overcome the challenges of the tumor microenvironment by designing therapies tailored to the secretome profiles of individual cancer patients. In addition, advances in proteomic techniques are highlighted as essential tools for unraveling the complexity of the tumor secretome, paving the way for improved cancer treatment outcomes.