PERK is a critical metabolic hub for immunosuppressive function in macrophages

The integrated stress response fine-tunes stem cell fate decisions upon serine deprivation and tissue injury

Epidermal stem cells produce the skin's barrier that excludes pathogens and prevents dehydration. Hair follicle stem cells (HFSCs) are dedicated to bursts of hair regeneration, but upon injury, they can also reconstruct, and thereafter maintain, the overlying epidermis. How HFSCs balance these fate choices to restore physiologic function to damaged tissue remains poorly understood. Here, we uncover serine as an unconventional, non-essential amino acid that impacts this process. When dietary serine dips, endogenous biosynthesis in HFSCs fails to meet demands (and vice versa), slowing hair cycle entry. Serine deprivation also alters wound repair, further delaying hair regeneration while accelerating re-epithelialization kinetics. Mechanistically, we show that HFSCs sense each fitness challenge by triggering the integrated stress response, which acts as a rheostat of epidermal-HF identity. As stress levels rise, skin barrier restoration kinetics accelerate while hair growth is delayed. Our findings offer potential for dietary and pharmacological intervention to accelerate wound healing.

Endoplasmic reticulum stress on glioblastoma: Tumor growth promotion and immunosuppression

Exogenous or endogenous factors such as hypoxia, nutritional deficiencies, acidic microenvironments and their own high metabolic demands usually lead to tumor endoplasmic reticulum dysfunction and trigger endoplasmic reticulum stress (ERS). ERS sensors intercept such stress signals, which subsequently initiate the unfolded protein response (UPR), enabling tumor cells to adapt robustly in the hostile environment. Many studies have found that the ERS response affects a variety of tumor-infiltrating immune cells and suppresses their anti-tumor responses through different mechanisms. Given that glioblastoma (GBM) are immunosuppressive "cold tumors" with a poor prognosis. This paper not only discusses the promotion of GBM growth by ERS response, but also reviews the mechanisms by which ERS response promotes an immunosuppressive microenvironment.

Sphingolipid synthesis in tumor-associated macrophages confers immunotherapy resistance in hepatocellular carcinoma

Dysregulated metabolism of immune cells in the tumor microenvironment leads to immune evasion and tumor progression. As a major cell component in the tumor, the metabolic reprogramming of tumor-associated macrophages (TAMs) creates an immunosuppressive microenvironment in hepatocellular carcinoma (HCC). Our study found that sphingolipid (particularly, sphingosine-1-phosphate or S1P) levels are a clinical indicator for prognosis and immunotherapy response in patients with HCC. S1P primarily derived from TAMs, where NIMA-related kinase 2 (NEK2) plays a key role in controlling the activity of serine palmitoyl-CoA transferase, a rate-limiting enzyme in S1P biosynthesis. The S1P produced by NEK2hi TAMs promotes hepatic tumor progression and confers immunotherapy resistance. Targeting S1P synthesis with a NEK2 inhibitor or S1P antagonist disrupted the immunosuppressive function of macrophages, shifted regulatory T cells (Tregs) to TH17 cells, and increased the number and activity of tumor-infiltrating T effectors, thereby enhancing antitumor efficacy in synergy with immune checkpoint blockade therapy.

The PERK/ATF4 pathway is required for metabolic reprogramming and progressive lung fibrosis

Asbestosis is a prototypical type of fibrosis that is progressive and does not resolve. ER stress is increased in multiple cell types that contribute to fibrosis; however, the mechanism(s) by which ER stress in lung macrophages contributes to fibrosis is poorly understood. Here, we show that ER stress resulted in protein kinase RNA-like ER kinase (PERK; Eif2ak3) activation in humans with asbestosis. Similar results were seen in asbestos-injured mice. Mice harboring a conditional deletion of Eif2ak3 were protected from fibrosis. Lung macrophages from asbestosis individuals had evidence of metabolic reprogramming to fatty acid oxidation (FAO). Eif2ak3fl/fl mice had increased oxygen consumption rate (OCR), whereas OCR in Eif2ak3-/- Lyz2-cre mice was reduced to control levels. PERK increased activating transcription factor 4 (Atf4) expression, and ATF4 bound to the Ppargc1a promoter to increase its expression. GSK2656157, a PERK-specific inhibitor, reduced FAO, Ppargc1a, and Aft4 in lung macrophages and reversed established fibrosis in mice. These observations suggest that PERK is a therapeutic target to reverse established fibrosis.

Inhibition of IRE1α Alleviates Renal Fibrosis and Downregulates M1 Macrophage Activation via the p38 MAPK Pathway

The enhanced M1 macrophage activation and proportion significantly promote the progression of renal fibrosis in the unilateral ureteral obstruction (UUO) model, while the underlying mechanisms need to be further studied. Here, we examined whether or not endoplasmic reticulum (ER) stress contributed to M1 macrophage activation and the mechanisms in this process. In the UUO mouse model, the proportion of M1 macrophages could be significantly increased in the early renal fibrosis, with the ER stress activated. The inhibitor of ER stress (4-PBA) significantly suppressed the activation of M1 macrophages and alleviated the renal fibrosis in the UUO mouse model. Furthermore, the renal fibrosis could be relieved after the administration of IRE1α inhibitor (4μ8C), with the downregulation of ER stress and M1 macrophage activation. Mechanistically, ER stress-enhanced activation of M1 macrophages was regulated through the IRE1α/XBP1s-p38 MAPK pathway. IRE1α-deficient macrophages could alleviate the renal fibrosis in the UUO mouse model. Thus, our findings suggest that the ER stress pathway regulates M1 macrophage activation in the UUO model, which provides a novel therapeutic approach for renal fibrosis.

Synergistic anti-tumor effects of mRNA vaccine and PERK inhibitor combination in melanoma treatment

Melanoma is a highly aggressive form of skin cancer. mRNA vaccines deliver genetic material encoding specific antigens into cells, thereby triggering the host immune system to produce the antigen. Gp-100, an antigenic protein expressed on the surface of melanoma cells, serves as a target mRNA to stimulate the cytotoxic T lymphocyte (CTL) response. However, the absence of natural killer (NK) cells can lead to significant tumor cell proliferation. Gardiquimod, a TLR7 agonist, enhances NK cell cytotoxicity, promoting tumor clearance. In advanced melanoma, the unfolded protein response (UPR) often becomes dysregulated. By inhibiting protein kinase R-like ER kinase (PERK), the UPR can be disrupted, inducing apoptosis in cancer cells and shifting the tumor microenvironment (TME) towards an increased M1/M2 macrophage ratio. This study developed a cationic liposome-based mRNA vaccine (GD-LPR) using DOTMA to co-deliver gp-100 mRNA and the TLR7 agonist Gardiquimod, combined with the PERK inhibitor GSK2656157 (GSK), for synergistic melanoma immunotherapy. GD-LPR achieved 95 % mRNA encapsulation efficiency and demonstrated enhanced dendritic cell maturation and NK cell activation both in vitro and in vivo. In subcutaneous melanoma models, GD-LPR+GSK reduced tumor volume and prolonged survival by modulating the tumor microenvironment (TME): increasing CD8+ T cells (Fig. 3 f), repolarizing M2 to M1 macrophages (Fig. 4 f), and suppressing IL-10 while elevating pro-inflammatory cytokines (IL-2, IFN-γ, TNF-α). Mechanistically, GSK inhibited PERK/ATF-4 signaling, synergizing with GD-LPR to suppress lung metastasis. The combination of the GD-LPR vaccine and GSK provides new potential strategies for treating melanoma, particularly in subcutaneous tumors and lung metastases.

PERK+ Macrophages Drive Immunotherapy Resistance in Lymph Node Metastases of Oral Squamous Cell Carcinoma

PURPOSE

Neoadjuvant anti-PD-1 immunotherapy combined with chemotherapy has shown promising pathologic responses in various cancers, including oral squamous cell carcinoma (OSCC). However, the pathologic response of lymph node (LN) metastases remains poorly understood. This study aims to systematically evaluate the pathologic response rates (pRR) of LN metastases in patients with OSCC and identify potential targets to improve therapeutic outcomes.

PATIENTS AND METHODS

We assessed the pRRs of LN metastases and matched primary tumors (PT) in patients with OSCC enrolled in a randomized, two-arm, phase II clinical trial (NCT04649476). Single-cell and spatial transcriptomics and multiplex IHC were performed to analyze the tumor microenvironment and identify potential therapeutic targets in LN metastases. A neoadjuvant orthotopic OSCC mouse model was established to evaluate the therapeutic potential of these targets.

RESULTS

We observed significant heterogeneity in pathologic regression of LN metastases, with lower pRRs compared with PTs. pRRs in LN metastases were correlated with overall and disease-free survival in patients with OSCC. We identified an abundance of macrophages in LN metastases exhibiting an unfolded protein response and activated protein kinase RNA-like endoplasmic reticulum kinase (PERK) signaling. These macrophages contributed to an extracellular matrix-enriched microenvironment through interactions with fibroblasts, which hindered T cell-mediated cytotoxicity. Pharmacologic inhibition of the PERK pathway significantly enhanced anti-PD-1 therapy in LN metastases and PTs in the mouse model.

CONCLUSIONS

Our study confirms that the pathologic response of LN metastases in patients with OSCC undergoing neoadjuvant immunotherapy or immunochemotherapy is inferior to that of PTs. It suggests that targeting the PERK pathway in macrophages could be a potential strategy to enhance treatment outcomes.

Transforming the Tumor Microenvironment: An Outstanding AIE-Active Photosensitizer to Boost the Effectiveness of Immunotherapy

Immunotherapy, currently the most promising therapeutic approach for cancer, has shown significant efficacy. However, its clinical effectiveness is often constrained by such factors as tumor heterogeneity, the abundance of M2 macrophages, tumor-vascular hypoxia, and the immunosuppressive microenvironment created by immune checkpoint (IC) complexes. In this work, an effective photosensitizer (TSPA) with aggregation-induced emission (AIE) nature is adopted to counter above limitations. The synthesized TSPA demonstrated potent efficacy in eradicating primary tumors because of their effective generation reactive oxygen species (ROS) after undergoing photodynamic therapy (PDT) process. Moreover, TSPA can improve hypoxic conditions in tumor by normalizing blood vessels, and can instigate immunogenic cell death (ICD), thus stimulating immune cell activation. TSPA demonstrates the ability to reprogram M2 tumor-associated macrophages (TAMs) into the anti-tumor M1 phenotype, thereby increasing the infiltration of M1 macrophages within the tumor. This procedure notably ameliorates the immune microenvironment, effectively suppressing the long-term metastasis of breast cancer (BC). This research notably enhances the efficiency of tumor immunotherapy and is anticipated to emerge as a new strategy for improving the tumor's immunosuppressive microenvironment and overcoming immune evasion.

Lithium carbonate exposure disrupts neurodevelopment by perturbing primary cilia and ER homeostasis

Lithium, which is widely used in medicine and batteries, has become increasingly prevalent in the environment, raising concerns about its impact on human health. Lithium carbonate (Li2CO3) is a common treatment and relapse prevention method for bipolar disorder. It can freely cross the placental barrier; however, lithium treatment is accompanied by side effects, particularly in women of reproductive age. Among these, neural tube defects (NTDs) have the most severe impact on nervous system development; however, their underlying mechanisms remain unclear. This study explored the potential mechanisms by which Li2CO3 exposure contributes to NTDs. Pregnant mice were intraperitoneally injected with Li2CO3 (360 mg/kg), which mimicked high-exposure scenarios such as an unintended pregnancy during lithium therapy or exposure to industrial contamination. Embryos were assessed for morphological changes, primary cilia length, and endoplasmic reticulum (ER) homeostasis using histological analysis, scanning electron microscopy, PCR array analysis, immunofluorescence, and quantitative real-time PCR. Network and bioinformatics analyses were used to identify primary molecular targets and pathways. We also evaluated the effects of inositol supplementation on cilia during Li2CO3 exposure. The results revealed that treatment with Li2CO3 at 360 mg/kg induced exencephaly in some embryos, reduced primary cilia length, and dysregulated cilia-associated gene expression in the neural tube. PCR Array, network metabolism, and immunofluorescence analyses revealed that HSP90AB1, a critical regulator of ER homeostasis, was upregulated in Li2CO3-treated embryos with NTDs. Li2CO3 exposure disturbed ER homeostasis in the developing brain. Interestingly, inositol supplementation partially rescued ciliogenesis impairment in lithium-treated NIH3T3 cells. Li2CO3 exposure disrupted primary ciliary development and ER homeostasis in the embryonic neural tube. Maintaining adequate maternal inositol levels during Li2CO3 exposure before and during pregnancy prevents NTDs. These findings help in better understanding and reassessing the risks associated with lithium, especially in terms of maternal and fetal health.

Unraveling UPR-mediated intercellular crosstalk: Implications for immunotherapy resistance mechanisms

Endoplasmic reticulum (ER) is the critical organelle that regulates essential cellular processes, including protein synthesis, folding, and post-translational modification, as well as lipid metabolism and calcium homeostasis. Disruption in ER homeostasis leads to a condition known as ER stress, characterized by the accumulation of misfolded or unfolded proteins. This triggers the unfolded protein response (UPR), an adaptive pathway mediated by three ER-resident sensors: inositol-requiring enzyme 1α (IRE1α), protein kinase R-like ER kinase (PERK), and activating transcription factor 6 (ATF6). Increasing evidence highlights sustained UPR activation in malignant and immune cells within the tumor microenvironment (TME), which promotes tumor progression and metastasis while simultaneously impairing antitumor immunity. This review explores how UPR-driven intercellular signaling influences immunotherapy resistance, focusing on the alterations occurring in tumor cells as well as in the surrounding immune environment. By providing insights into these mechanisms, we aim to highlight the therapeutic potential of targeting the UPR pathways in modulating cancer immunity.

Monoallelic TYROBP deletion is a novel risk factor for Alzheimer's disease

Biallelic loss-of-function variants in TYROBP and TREM2 cause autosomal recessive presenile dementia with bone cysts known as Nasu-Hakola disease (NHD, alternatively polycystic lipomembranous osteodysplasia with sclerosing leukoencephalopathy, PLOSL). Some other TREM2 variants contribute to the risk of Alzheimer's disease (AD) and frontotemporal dementia, while deleterious TYROBP variants are globally extremely rare and their role in neurodegenerative diseases remains unclear. The population history of Finns has favored the enrichment of deleterious founder mutations, including a 5.2 kb deletion encompassing exons 1-4 of TYROBP and causing NHD in homozygous carriers. We used here a proxy marker to identify monoallelic TYROBP deletion carriers in the Finnish biobank study FinnGen combining genome and health registry data of 520,210 Finns. We show that monoallelic TYROBP deletion associates with an increased risk and earlier onset age of AD and dementia when compared to noncarriers. In addition, we present the first reported case of a monoallelic TYROBP deletion carrier with NHD-type bone cysts. Mechanistically, monoallelic TYROBP deletion leads to decreased levels of DAP12 protein (encoded by TYROBP) in myeloid cells. Using transcriptomic and proteomic analyses of human monocyte-derived microglia-like cells, we show that upon lipopolysaccharide stimulation monoallelic TYROBP deletion leads to the upregulation of the inflammatory response and downregulation of the unfolded protein response when compared to cells with two functional copies of TYROBP. Collectively, our findings indicate TYROBP deletion as a novel risk factor for AD and suggest specific pathways for therapeutic targeting.

Immunometabolism of Innate Immune Cells in Gastrointestinal Cancer

Cancer cells are often described as voracious consumers of nutrients, with glucose frequently cited as a key energy source; however, their metabolic plasticity allows them to adapt and utilize various substrates, including lipids and amino acids, to sustain growth and survival. However, the metabolic demands of immune cells within the tumor microenvironment (TME) are less commonly discussed despite their critical role in shaping the immune response. In this review, we explored the intricate interplay between immunometabolism and innate immunity cells in gastrointestinal cancers. We focused on how metabolic pathways, including glycolysis, fatty acid oxidation, and amino acid metabolism, drive the immunosuppressive functions of myeloid-derived suppressor cells (MDSCs) and tumor-associated neutrophils (TANs), tumor-associated macrophages (TAMs) and innate lymphocyte subsets such as NK cells. These cells contribute to a hostile immune landscape, supporting tumor growth and evasion from immune surveillance in a phenomenon of tumor-derived immunosuppression. Additionally, we investigated the influence of dietary interventions on the metabolic reprogramming of these immune cells, highlighting how nutrition can modulate the TME. Finally, we discussed emerging therapeutic strategies that target metabolic vulnerabilities in MDSCs, TANs, NK cells, and monocytes, offering a novel avenue for enhancing antitumor immunity. By dissecting these mechanisms, we aim to provide insights into how metabolic pathways can be harnessed to improve cancer treatment outcomes. This review underscores the importance of understanding immunometabolism not only as a driver of immune suppression but also as a potential therapeutic target in gastrointestinal cancer.

Dietary targeting of TRPM8 rewires macrophage immunometabolism reducing colitis severity

The interplay between diet, host genetics, microbiota, and immune system has a key role in the pathogenesis of inflammatory bowel disease (IBD). Although the causal pathophysiological mechanisms remain unknown, numerous dietary nutrients have been shown to regulate gut mucosal immune function, being effective in influencing innate or adaptive immunity. Here, we proved that transient receptor potential melastatin 8 (TRPM8), a non-selective cation channel, mediates LPS- evoked Ca2+ influx in macrophages leading to their activation. Additionally, we showed that TRPM8 is selectively blocked by the dietary flavonoid luteolin, which induced a pro-tolerogenic phenotype in pro-inflammatory macrophages. Accordingly, genetic deletion of Trpm8 in macrophages caused a deficit in the activation of pro-inflammatory metabolic and transcriptional reprogramming, leading to reduced production of key pro-inflammatory cytokines such as interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α. The TRPM8 anti-inflammatory effect was found to be dependent on lactate which in turn induces IL-10 gene expression. Adoptive transfer of TRPM8-deficient bone marrow in wild-type mice improved intestinal inflammation in a model of colitis. Accordingly, oral administration of luteolin protected mice against colitis through an impairment in the innate immune response. Our study reveals the potential of targeting TRPM8 through specific nutrient interventions to regulate immune function in sub-clinical scenarios or to treat inflammatory diseases, primarily driven by chronic immune responses, such as IBD.

Metabolic Dialogue Shapes Immune Response in the Tumor Microenvironment

The fate of immune cells is fundamentally linked to their metabolic program, which is also influenced by the metabolic landscape of their environment. The tumor microenvironment represents a unique system for intercellular metabolic interactions, where tumor-derived metabolites suppress effector CD8+ T cells and promote tumor-promoting macrophages, reinforcing an immune-suppressive niche. This review will discuss recent advancements in metabolism research, exploring the interplay between various metabolites and their effects on immune cells within the tumor microenvironment.

Embracing diversity: macrophage complexity in cancer

Macrophages are myeloid cells that receive, integrate, and respond to tumoral cues. Tumors evolve and are shaped by macrophages, with tumor-associated macrophage (TAM)-tumor sculpting capacities going beyond an increase in their cellular mass. Longitudinal and local heterogeneity of TAM states is now possible with the use of single-cell and spatial transcriptomics. However, understanding TAM biology and its fundamental functional programs is still challenging, probably because of the lack of models that fully integrate TAM complexity. Here, we aim to review TAM diversity not only at the level of single-cell phenotypes but also by integrating complex physiological signals that determine their complexity and plasticity in tumors.

lncRNA ENST000000454471 promotes lung adenocarcinoma progression and tumor immune escape: Protein structure and biological functions of histone deacetylase 8

The purpose of this study was to investigate the role of lncRNA ENST0000000454471 in lung adenocarcinoma progression and tumor immune escape, and to analyze the protein structure and biological function of HDAC8. Various experimental techniques were used in this study, including real-time quantitative PCR (qPCR) to detect the difference in lncRNA ENST0000000454471 expression between lung adenocarcinoma tissue and normal lung tissue. Cell experiments included cell proliferation, migration and invasion experiments to evaluate the effect of lncRNA ENST0000000454471 on the behavior of lung adenocarcinoma cells. Molecular biological techniques such as chromatin immunoprecipitation (ChIP) and co-immunoprecipitation (Co-IP) were used to investigate the interaction between lncRNA ENST0000000454471 and HDAC8. The protein structure was analyzed by X-ray crystallography and molecular dynamics simulation. Cell experiments showed that overexpression of lncRNA ENST0000000454471 promoted the proliferation, migration and invasion of lung adenocarcinoma cells, and inhibitors of HDAC8 could reverse these effects. Further molecular mechanism studies showed that lncRNA ENST0000000454471 regulates the expression of several genes related to tumor progression and immune escape through interaction with HDAC8. Protein structure analysis revealed the active sites and regulatory regions of HDAC8, providing a structural basis for understanding its biological function.

Phosphatase PHLPP1 is an alveolar-macrophage-intrinsic transcriptional checkpoint controlling pulmonary fibrosis

Alveolar macrophages (AMs) are crucial for lung homeostasis, and their dysfunction causes uncontrolled fibrotic responses and pulmonary disorders. Protein phosphatases control multiple cellular events. However, whether nuclear phosphatases cooperate with histone modifiers to affect pulmonary fibrosis progress remains obscure. Here, we identified pleckstrin homology domain and leucine-rich repeat protein phosphatase 1 (PHLPP1) as a key protective factor for pulmonary fibrosis. Transcriptomics and epigenomics data confirmed that PHLPP1 selectively targeted Kruppel-like factor 4 (KLF4) for transcriptional inhibition in AMs. Nuclear PHLPP1 directly bound and dephosphorylated histone deacetylase 8 (HDAC8) at serine 39, thereby enhancing its deacetylase enzyme activity and subsequently suppressing KLF4 expression via the decreased histone acetylation and chromatin accessibility. Thus, loss of PHLPP1 amplified KLF4-centric profibrotic transcriptional program in AMs, while intratracheal administration of Klf4-short hairpin RNA (shRNA) adeno-associated virus ameliorated lung fibrosis in PHLPP1-deficient mice. Our study implies that targeting decreased PHLPP1 in AMs might be a promising therapeutic strategy for pulmonary fibrosis.

Targeting cTRIP12 counteracts ferroptosis resistance and augments sensitivity to immunotherapy in pancreatic cancer

AIMS

Current therapeutic strategies for pancreatic ductal adenocarcinoma (PDAC) have limited efficacy in increasing patient survival rates, largely due to ferroptosis resistance and immunosuppression. The aim of this study is to identify molecular mechanisms associated with ferroptosis resistance and immunosuppression in PDAC tumour cells.

METHODS

Circular RNA sequencing (circRNA-seq) was performed on clinical samples to identify potential circRNAs that mediate ferroptosis resistance. C11-BODIPY staining, FerroOrange staining, the glutathione ratio, malondialdehyde quantification, and transmission electron microscopy were employed to assess ferroptosis. RNA pulldown, mass spectrometry, RNA immunoprecipitation, and coimmunoprecipitation assays were conducted to investigate the molecular mechanisms involved. A HuNSG mouse xenograft tumour model was utilized to validate therapeutic agents.

RESULTS

A circRNA derived from TRIP12 (cTRIP12) was identified in PDAC samples resistant to ferroptosis. cTRIP12 knockdown increased the sensitivity of PDAC cells to ferroptosis and immunotherapy. Subsequent mechanistic studies revealed that cTRIP12 specifically binds to the O-linked N-acetylglucosamine transferase (OGT) protein and increases intracellular O-GlcNAcylation levels, leading to increased protein levels of ferritin heavy chain (FTH) and PD-L1 in tumour cells. Notably, high cTRIP12 expression suppressed ferroptosis sensitivity and increased immune resistance in PDAC cells by functioning as a protein scaffold through its interaction with OGT and protein kinase R-like endoplasmic reticulum kinase (PERK). cTRIP12 inhibition induced ferroptosis in PDAC cells by reducing FTH and PD-L1 expression and synergistically increased the immunotherapy efficacy. In vivo animal experiments confirmed that the triple therapy consisting of GSK2656157, erastin, and anti-CTLA-4 effectively suppressed the progression of PDAC in tumours with high cTRIP12 expression.

CONCLUSION

We elucidated the molecular mechanisms underlying the simultaneous occurrence of ferroptosis resistance and immune suppression in PDAC patients. Our study provides a novel therapeutic strategy that could promote ferroptosis in tumour cells and increase immunotherapy efficacy.

Unfolded protein responses: Dynamic machinery in wound healing

Skin wound healing is a dynamic process consisting of multiple cellular and molecular events that must be tightly coordinated to repair the injured tissue efficiently. The healing pace is decided by the type of injuries, the depth and size of the wounds, and whether wound infections occur. However, aging, comorbidities, genetic factors, hormones, and nutrition also impact healing outcomes. During wound healing, cells undergo robust processes of synthesizing new proteins and degrading multifunctional proteins. This imposes an increasing burden on the endoplasmic reticulum (ER), causing ER stress. Unfolded protein response (UPR) represents a collection of highly conserved stress signaling pathways originated from the ER to maintain protein homeostasis and modulate cell physiology. UPR is known to be beneficial for tissue healing. However, when excessive ER stress exceeds ER's folding potential, UPR pathways trigger cell apoptosis, interrupting tissue regeneration. Understanding how UPR pathways modulate the skin's response to injuries is critical for new interventions toward the control of acute and chronic wounds. Herein, in this review, we focus on the participation of the canonical and noncanonical UPR pathways during different stages of wound healing, summarize the available evidence demonstrating UPR's unique position in balancing homeostasis and pathophysiology of healing tissues, and highlight the understudied areas where therapeutic opportunities may arise.

Sustained therapeutic effects of self-assembled hyaluronic acid nanoparticles loaded with α-Ketoglutarate in various osteoarthritis stages

Osteoarthritis (OA) is a prevalent degenerative disease characterized by irreversible destruction of articular cartilage, for which no current drugs are known to modify its progression. While intra-articular (IA) injections of hyaluronic acid (HA) offer temporary relief, their effectiveness and long-term benefits are debated. Alpha-ketoglutarate (αKG) has potential chondroprotective properties, but its use is limited by a short half-life and poor cartilage-targeting efficiency. Here, we developed self-assembled HA-αKG nanoparticles (NPs) to combine the benefits of both HA and αKG, showing stability, bioavailability, and sustained pH-responsive release in the knee joint. In both early and advanced OA stages in mice, HA, αKG, and HA-αKG NPs could relieve pain, enhance mobility, and reduce cartilage damage, with HA-αKG NPs demonstrating the best efficacy. Mechanistically, αKG not only promotes cartilage matrix synthesis but also inhibits degradation by activating the PERK-ATF4 signaling pathway to reduce endoplasmic reticulum stress (ERS) in chondrocytes. This study highlights the therapeutic potential of HA-αKG NPs for treating various OA stages, with efficient and sustained effects, suggesting rapid clinical adoption and high acceptability among clinicians and patients.

Metabolism-epigenetic interaction-based bone and dental regeneration: From impacts and mechanisms to treatment potential

Metabolic pathways exhibit fluctuating activities during bone and dental loss and defects, suggesting a regulated metabolic plasticity. Skeletal remodeling is an energy-demanding process related to altered metabolic activities. These metabolic changes are frequently associated with epigenetic modifications, including variations in the expression or activity of enzymes modified through epigenetic mechanisms, which directly or indirectly impact cellular metabolism. Metabolic reprogramming driven by bone and dental conditions alters the epigenetic landscape by modulating the activities of DNA and histone modification enzymes at the metabolite level. Epigenetic mechanisms modulate the expression of metabolic genes, consequently influencing the metabolome. The interplay between epigenetics and metabolomics is crucial in maintaining bone and dental homeostasis by preserving cell proliferation and pluripotency. This review, therefore, aims to examine the effects of metabolic reprogramming in bone and dental-related cells on the regulation of epigenetic modifications, particularly acetylation, methylation, and lactylation. We also discuss the effects of chromatin-modifying enzymes on metabolism and the potential therapeutic benefits of dietary compounds as epigenetic modulators. In this review, we highlight the inconsistencies in current research findings and suggest potential approaches to translate fundamental insights into clinical treatments for bone and tooth diseases.

Biomimetic Membrane Vesicles Reprogram Microglia Polarization and Remodel the Immunosuppressive Microenvironment of Glioblastoma via PERK/HIF-1α/Glycolysis Pathway

The malignant interaction between tumor cells and immune cells is one of the important reasons for the rapid progression and refractoriness of glioblastoma (GBM). As an essential metabolic center of M2 macrophages, the inhibition of protein kinase RNA-like endoplasmic reticulum kinase (PERK) leads to the reduction of M2 macrophages. Nevertheless, the restriction of the blood-brain barrier (BBB) and non-specific cell targeting hinder the application of PERK inhibitors in GBM. Herein, the optimal NP-M-M2pep is developed successfully, which has shown the capacity of BBB penetration and specific targeting of M2 microglia. In addition to inhibiting the polarization of M2 microglia, the administration of iPERK@NP-M-M2pep reprogrammed M2 microglia into M1 ones in vitro via PERK/HIF-1α/glycolysis pathway. Efficient brain accumulation of nanoparticles is achieved after tail vein injection, with effective inhibition of GBM progression after one course of treatment. The glioma-associated microglia and macrophages (GAM) with M2 type are induced to M1 and the immunosuppressive TME is remodeled by upregulating immunostimulatory cells and downregulating immunosuppressive cells. In summary, the biomimetic membrane vesicles (BMVs) specifically delivered iPERK to GAMs offer an inspiring strategy to reprogram microglia polarization, re-educate immunosuppressive TME, and inhibit the progression of GBM.

Cancer ATF4-mediated CD58 endocytosis impairs anti-tumor immunity and immunotherapy

Co-stimulatory molecules are imperative for CD8+ T cells to eliminate target cell and maintain sustained cytotoxicity. Despite an advanced understanding of the co-stimulatory molecules deficiency that results in tumor escape, the tumor cell-intrinsic mechanisms that regulate co-stimulatory molecules remain enigmatic, and an in-depth dissection could facilitate the improvement of treatment options. To this end, in this study, we report that the deficiency of the critical costimulatory molecule CD58, mediated by the expression of ATF4 in tumor cells, impairs the formation of immunological synapses (IS) and leads to the deterioration of antitumor immune function of CD8+ T cells. Mechanistically, ATF4 transcriptionally upregulated dynamin 1 (DNM1) expression leading to DNM1-dependent endocytosis (DDE)-mediated degradation of CD58. Furthermore, administration of DDE inhibitor prochlorperazine or ATF4 knockdown effectively restored CD58 expression, boosting CD8+ T cell cytotoxicity and immunotherapy efficiency. Thus, our study reveals that ATF4 in tumor cells weakens CD58 expression to interfere with complete IS formation, and indicates potential approaches to improve the cytolytic function of CD8+ T cell in tumor immunotherapy.

PERK-Olating Through Cancer: A Brew of Cellular Decisions

The type I protein kinase PERK is an endoplasmic reticulum (ER) transmembrane protein that plays a multifaceted role in cancer development and progression, influencing tumor growth, metastasis, and cellular stress responses. The activation of PERK represents one of the three signaling pathways induced during the unfolded protein response (UPR), which is triggered, in particular, in tumor cells that constitutively experience various intracellular and extracellular stresses that impair protein folding within the ER. PERK activation can lead to both pro-survival and proapoptotic outcomes, depending on the cellular context and the extent of ER stress. It helps the reprogramming of the gene expression in cancer cells, thereby ensuring survival in the face of oncogenic stress, such as replicative stress and DNA damage, and also microenvironmental challenges, including hypoxia, angiogenesis, and metastasis. Consequently, PERK contributes to tumor initiation, transformation, adaptation to the microenvironment, and chemoresistance. However, sustained PERK activation in cells can also impair cell proliferation and promote apoptotic death by various interconnected processes, including mitochondrial dysfunction, translational inhibition, the accumulation of various cellular stresses, and the specific induction of multifunctional proapoptotic factors, such as CHOP. The dual role of PERK in promoting both tumor progression and suppression makes it a complex target for therapeutic interventions. A comprehensive understanding of the intricacies of PERK pathway activation and their impact is essential for the development of effective therapeutic strategies, particularly in diseases like cancer, where the ER stress response is deregulated in most, if not all, of the solid and liquid tumors. This article provides an overview of the knowledge acquired from the study of animal models of cancer and tumor cell lines cultured in vitro on PERK's intracellular functions and their impact on cancer cells and their microenvironment, thus highlighting potential new therapeutic avenues that could target this protein.

Regulatory function of endoplasmic reticulum stress in colorectal cancer: Mechanism, facts, and perspectives

Colorectal cancer (CRC) is an exceedingly common and profoundly impactful malignancy of the digestive system, posing a grave threat to human health. Endoplasmic reticulum stress (ERS) is an intracellular biological reaction that mobilizes the unfolded protein response (UPR) to tackling dysregulation in protein homeostasis. This process subtly modulates the cell to either restore normal cellular function or steer it towards apoptosis. The high metabolic demands of CRC cells sculpt a rigorous tumor microenvironment (TME), compelling CRC cells to experience ERS. Adaptive responses induced by mild ERS furnish the necessary conditions for the survival of CRC cells, whereas the cell death mechanisms triggered by sustained ERS could be considered a prospective strategy for cancer therapy. Considering the complex regulation of ERS in cancer development, this article offers a comprehensive review of the molecular mechanisms through which ERS influences CRC fate. It provides crucial insights for exploring the role of ERS in the occurrence and progression of CRC, laying a new theoretical foundation for devising precise therapeutic strategies targeting ERS. Furthermore, by synthesizing extensive clinical and preclinical studies, we delve into therapeutic strategies targeting ERS, including the potential of targeting ERS in immunotherapy, the utilization of native compounds, advancements in proteasome inhibitors, and the potential synergies of these strategies with traditional chemotherapy agents and emerging therapeutic approaches.

Harnessing amino acid pathways to influence myeloid cell function in tumor immunity

Amino acids are pivotal regulators of immune cell metabolism, signaling pathways, and gene expression. In myeloid cells, these processes underlie their functional plasticity, enabling shifts between pro-inflammatory, anti-inflammatory, pro-tumor, and anti-tumor activities. Within the tumor microenvironment, amino acid metabolism plays a crucial role in mediating the immunosuppressive functions of myeloid cells, contributing to tumor progression. This review delves into the mechanisms by which specific amino acids-glutamine, serine, arginine, and tryptophan-regulate myeloid cell function and polarization. Furthermore, we explore the therapeutic potential of targeting amino acid metabolism to enhance anti-tumor immunity, offering insights into novel strategies for cancer treatment.

Interferon-driven Metabolic Reprogramming and Tumor Microenvironment Remodeling

IFNs play a critical role in cancer biology, including impacting tumor cell behavior and instructing the tumor microenvironment (TME). IFNs recently have been shown to reprogram tumor metabolism through distinct mechanisms. Furthermore, IFNs shape the TME by modulating immune cell infiltration and function, contributing to the intricate interaction between the tumor and stromal cells. This review summarizes the effects of IFNs on metabolic reprogramming and their impacts on the function of immune cells within the TME, with a particular focus on the dual roles of IFNs in mediating both anti-tumor and pro-tumor immune responses. Understanding the significance of IFNs-mediated processes aids to advise future therapeutic strategies in cancer treatment.

Linking macrophage metabolism to function in the tumor microenvironment

Macrophages are present at high frequency in most solid tumor types, and their relative abundance negatively correlates with therapy responses and survival outcomes. Tissue-resident macrophages are highly tuned to integrate tissue niche signals, and multiple factors within the idiosyncratic tumor microenvironment (TME) drive macrophages to polarization states that favor immune suppression, tumor growth and metastasis. These diverse functional states are underpinned by extensive and complex rewiring of tumor-associated macrophage (TAM) metabolism. In this Review, we link distinct and specific macrophage functional states within the TME to major, phenotype-sustaining metabolic programs and discuss the metabolic impact of macrophage-modulating therapeutic interventions.

Deciphering SPP1-related macrophage signaling in the pathogenesis of intervertebral disc degeneration

This study delved into the molecular mechanisms underlying mechanical stress-induced intervertebral disc degeneration (msi-IDD) through single-cell and high-throughput transcriptome sequencing in mouse models and patient samples. Results exhibited an upsurge in macrophage presence in msi-IDD intervertebral disc (IVD) tissues, with secreted phosphoprotein 1 (SPP1) identified as a pivotal driver exacerbating degeneration via the protein kinase RNA-like endoplasmic reticulum kinase/ activating transcription factor 4/ interleukin-10 (PERK/ATF4/IL-10) signaling axis. Inhibition of SPP1 demonstrated promising outcomes in mitigating msi-IDD progression in both in vitro and in vivo models. These findings underscore the therapeutic promise associated with the modulation of the PERK signaling pathway in IDD, shedding light on the pathogenesis of msi-IDD and proposing a promising avenue for intervention strategies.

Emerging role of metabolic reprogramming in the immune microenvironment and immunotherapy of thyroid cancer

The metabolic reprogramming of cancer cells is a hallmark of many malignancies. To meet the energy acquisition needs of tumor cells for rapid proliferation, tumor cells reprogram their nutrient metabolism, which is caused by the abnormal expression of transcription factors and signaling molecules related to energy metabolic pathways as well as the upregulation and downregulation of abnormal metabolic enzymes, receptors, and mediators. Thyroid cancer (TC) is the most common endocrine tumor, and immunotherapy has become the mainstream choice for clinical benefit after the failure of surgical, endocrine, and radioiodine therapies. TC change the tumor microenvironment (TME) through nutrient competition and metabolites, causing metabolic reprogramming of immune cells, profoundly changing immune cell function, and promoting immune evasion of tumor cells. A deeper understanding of how metabolic reprogramming alters the TME and controls immune cell fate and function will help improve the effectiveness of TC immunotherapy and patient outcomes. This paper aims to elucidate the metabolic communication that occurs between immune cells around TC and discusses how metabolic reprogramming in TC affects the immune microenvironment and the effectiveness of anti-cancer immunotherapy. Finally, targeting key metabolic checkpoints during metabolic reprogramming, combined with immunotherapy, is a promising strategy.

The role of the C5a-C5aR pathway in iron metabolism and gastric cancer progression

Gastric cancer continues to be a leading global health concern, with current therapeutic approaches requiring significant improvement. While the disruption of iron metabolism in the advancement of gastric cancer has been well-documented, the underlying regulatory mechanisms remain largely unexplored. Additionally, the complement C5a-C5aR pathway has been identified as a crucial factor in gastric cancer development. The impact of the complement system on iron metabolism and its role in gastric cancer progression is an area warranting further investigation. Our research demonstrates that the C5a-C5aR pathway promotes gastric cancer progression by enhancing iron acquisition in tumor cells through two mechanisms. First, it drives macrophage polarization toward the M2 phenotype, which has a strong iron-release capability. Second, it increases the expression of LCN2, a high-affinity iron-binding protein critical for iron export from tumor-associated macrophages, by activating endoplasmic reticulum stress in these cells. Both mechanisms facilitate the transfer of iron from macrophages to cancer cells, thereby promoting tumor cell proliferation. This study aims to elucidate the connection between the complement C5a-C5aR pathway and iron metabolism within the tumor microenvironment. Our data suggest a pivotal role of the C5a-C5aR pathway in tumor iron management, indicating that targeting its regulatory mechanisms may pave the way for future iron-targeted therapeutic approaches in cancer treatment.

CREB3L1 facilitates pancreatic tumor progression and reprograms intratumoral tumor-associated macrophages to shape an immunotherapy-resistance microenvironment

BACKGROUND

To date, a growing body of evidence suggests that unfolded protein response (UPR) sensors play a vital role in carcinogenesis. However, it remains unclear whether they are involved in pancreatic ductal adenocarcinoma (PDAC) and how they relate to clinical outcomes. This study aims to investigate the biological function and mechanism of how a novel UPR sensor, CREB3L1 works in PDAC and further evaluate its clinical application prospect.

METHODS

We tested UPR signaling including CREB3L1 in Thapsigargin-treated PDAC cells. Subsequently, we defined CREB3L1 expression and further analyzed its expression with clinical characteristics in PDAC. Then, we established gene-modified cells to determine whether CREB3L1 functions in cell proliferation and migration capacity. Besides, we constructed subcutaneously and orthotopically transplanted mice models to verify their progrowing function and pulmonary metastasis models to prove their proinvasion role. What's more, RNAseq, qPCR, Western blotting, immunohistochemistry and multicolor flow cytometry experiments were used to explore the mechanism of how CREB3L1 worked in PDAC. Lastly, CREB3L1 expression correlation with PDAC immunotherapy outcome and immune cell signatures were explored in the patients with advanced PDAC who received PD-1 antibody therapy.

RESULTS

We first confirmed CREB3L1 could be induced by endoplasmic reticulum stressor and found its aberrant activation was associated with poorer overall survival in PDAC patients indicating the protumor function of the new UPR sensor. Functionally, we confirmed CREB3L1 contributing to PDAC malignant progression including growth and metastasis by multiple in in vitro and in vivo models. Mechanistically, CREB3L1 upregulated COL3A1 and promoted dense stroma formation for facilitating PDAC and knocking down COL3A1 disrupted CREB3L1 protumor function. Furthermore, CREB3L1-induced TAM polarization toward an M2 phenotype and reduced the infiltration of CD8+ T cells. Clinically, CREB3L1 correlated with immune cell signatures as well as immune checkpoint blockade (ICB) treatment response and outcome that CREB3L1aberrant activation indicated poorer efficacy and worse prognosis than the low in PDAC which might empower clinical decision.

CONCLUSIONS

Collectively, this study revealed CREB3L1 facilitated PDAC progression, shaped an immune exclude tumor microenvironment and distinguished therapy response and outcome of ICB therapy indicating CREB3L1 could be a promising novel molecular target and biomarker for PDAC treatment.

Matairesinol repolarizes M2 macrophages to M1 phenotype to induce apoptosis in triple-negative breast cancer cells

OBJECTIVE

Triple-Negative Breast Cancer (TNBC), the most challenging subtype of Breast Cancer (BC), currently lacks targeted therapy, presenting a significant therapeutic gap in its management. Tumor Associated Macrophages (TAMs) play a significant role in TNBC progression and could be targeted by repolarizing them from M2 to M1 phenotype. Matairesinol (MAT), a plant lignan, has been shown to exhibit anticancer, anti-inflammatory and immunomodulatory activities. In this study, we explored how MAT-induced repolarization of THP-1-derived M2 macrophages towards the M1 phenotype, which could effectively target the TNBC cell line, MDA-MB-231.

METHODS

The differential expression of genes in THP-1-derived macrophages at mRNA levels was evaluated by RNAseq assay. An inverted microscope equipped with a CMOS camera was utilized to capture the morphological variations in THP-1 cells and THP-1-derived macrophages. Relative mRNA expression of M1 and M2 specific marker genes was quantified by qRT-PCR. Cell viability and induction of apoptosis were evaluated by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) and 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolylcarbocyanine iodide (JC-1 dye) assays, respectively.

RESULTS

MAT reduced the viability of M2a and M2d macrophages and repolarized them to M1 phenotype. Conditioned medium (CM) from MAT-treated M2a and M2d macrophages significantly reduced the viability of TNBC cells by apoptosis.

CONCLUSION

Targeting M2 macrophages is an important strategy to regulate cancer progression. Our study provides evidence that MAT may be a promising drug candidate for developing novel anti-TNBC therapy. However, further studies are warranted to thoroughly elucidate the molecular mechanism of action of MAT and evaluate its therapeutic potential in TNBC in vitro and in vivo models.

Dual functions of silibinin in attenuating aortic dissection via regulating iron homeostasis and endoplasmic reticulum stress against ferroptosis

Aortic dissection (AD) poses a significant threat to cardiovascular health globally, yet its underlying mechanisms remain elusive. Smooth muscle cells death and phenotypic switching are critically important pathological processes in AD. Currently, no pharmacological therapies have proven effective in managing AD. This study aims to elucidate the involvement of ferroptosis in AD progression and explore ferroptosis inhibition as a potential therapeutic approach for AD management. Elevated expression of ferroptosis markers (HMOX1, ACSL4, and 4-HNE) was observed in AD patients and β-Aminopropionitrile (BAPN)-induced mice. In vivo administration of silibinin (SIL) attenuated aortic dilation, inflammation, mitochondrial injury, and ferroptosis. SIL treatment enhanced cell viability and mitochondrial function while reducing reactive oxygen species (ROS) generation and mitigating ferroptosis in primary human aortic smooth muscle cells (HASMCs) induced by RSL3 or IKE. Mechanistically, RNA-sequencing analysis identified dysregulation of iron homeostasis and endoplasmic reticulum stress, which were modulated by SIL. Molecular docking, cellular thermal shift assay, drug affinity responsive target stability, and surface plasmon resonance analysis confirmed HMOX1 as a direct target of SIL, highlighting its role in modulating iron homeostasis. Moreover, NCT-502, a PHGDH inhibitor, reversed the protective effect of SIL in RSL3-induced HASMCs. Conversely, 4-PBA and ZnPP demonstrate a facilitative role. This suggests that SIL plays a crucial role in ferroptosis development by modulating iron homeostasis and endoplasmic reticulum stress-mediated serine biosynthesis, both in vitro and in vivo. Iron homeostasis and endoplasmic reticulum stress of HASMCs drive the development of aortic dissection. These findings unveil a novel role of SIL in mitigating ferroptosis in HASMCs, offering a promising therapeutic avenue for treating AD.

The UPRising connection between endoplasmic reticulum stress and the tumor microenvironment

The tumor microenvironment (TME) represents a dynamic network of cancer cells, stromal cells, immune mediators, and extracellular matrix components, crucial for cancer progression. Stress conditions such as oncogene activation, nutrient deprivation, and hypoxia disrupt the endoplasmic reticulum (ER), activating the unfolded protein response (UPR), the main adaptive mechanism to restore ER function. The UPR regulates cancer progression by engaging cell-autonomous and cell-non-autonomous mechanisms, reprogramming the stroma and promoting immune evasion, angiogenesis, and invasion. This review explores the role of UPR beyond cancer cells, focusing on how ER stress signaling reshapes the TME, supporting tumor growth. The therapeutic potential of targeting the UPR is also discussed.

EP152R-mediated endoplasmic reticulum stress contributes to African swine fever virus infection via the PERK-eIF2α pathway

African swine fever virus (ASFV) is a large, icosahedral, double-stranded DNA virus in the Asfarviridae family and the causative agent of African swine fever (ASF). ASFV causes a hemorrhagic fever with high mortality rates in domestic and wild pigs. ASFV contains an open reading frame named EP152R, previous research has shown that EP152R is an essential gene for virus rescue in swine macrophages. However, the detailed functions of ASFV EP152R remain elusive. Herein, we demonstrate that EP152R, a membrane protein located in the endoplasmic reticulum (ER), induces ER stress and swelling, triggering the PERK/eIF2α pathway, and broadly inhibiting host protein synthesis in vitro. Additionally, EP152R strongly promotes immune evasion, reduces cell proliferation, and alters cellular metabolism. These results suggest that ASFV EP152R plays a critical role in the intracellular environment, facilitating viral replication. Furthermore, virus-level experiments have shown that the knockdown of EP152R or PERK inhibitors efficiently affects viral replication by decreasing viral gene expression. In summary, these findings reveal a series of novel functions of ASFV EP152R and have important implications for understanding host-pathogen interactions.

Extrinsic and Cell-Intrinsic Stress in the Immune Tumor Micro-Environment

In continuously progressive tumor tissues, the causes of cellular stress are multiple: metabolic alterations, nutrient deprivation, chronic inflammation and hypoxia. To survive, tumor cells activate the stress response program, a highly conserved molecular reprogramming proposed to cope with challenges in a hostile environment. Not only cancer cells are affected, but stress responses in tumors also have a profound impact on their normal cellular counterparts: fibroblasts, endothelial cells and infiltrating immune cells. In recent years, there has been a growing interest in the interaction between cancer and immune cells, especially in difficult conditions of cellular stress. A growing literature indicates that knowledge of the molecular pathways activated in tumor and immune cells under stress conditions may offer new insights for possible therapeutic interventions. Counter-regulating the stress caused by the presence of a growing tumor can therefore be a weapon to limit disease progression. Here, we review the main pathways activated in cellular stress responses with a focus on immune cells present in the tumor microenvironment.

Single cell-spatial transcriptomics and bulk multi-omics analysis of heterogeneity and ecosystems in hepatocellular carcinoma

This study profiled global single cell-spatial-bulk transcriptome landscapes of hepatocellular carcinoma (HCC) ecosystem from six HCC cases and a non-carcinoma liver control donor. We discovered that intratumoral heterogeneity mainly derived from HCC cells diversity and pervaded the genome-transcriptome-proteome-metabolome network. HCC cells are the core driving force of taming tumor-associated macrophages (TAMs) with pro-tumorigenic phenotypes for favor its dominant growth. Remarkably, M1-types TAMs had been characterized by disturbance of metabolism, poor antigen-presentation and immune-killing abilities. Besides, we found simultaneous cirrhotic and HCC lesions in an individual patient shared common origin and displayed parallel clone evolution via driving disparate immune reprograms for better environmental adaptation. Moreover, endothelial cells exhibited phenotypically conserved but executed differential functions in a space-dependent manner. Further, the spatiotemporal traits of rapid recurrence niche genes were identified and validated by immunohistochemistry. Our data unravels the great significance of HCC cells in shaping vibrant tumor ecosystems corresponding to clinical scenarios.

Metabolic Reprogramming of Immune Cells in the Tumor Microenvironment

Metabolic reprogramming of immune cells within the tumor microenvironment (TME) plays a pivotal role in shaping tumor progression and responses to therapy. The intricate interplay between tumor cells and immune cells within this ecosystem influences their metabolic landscapes, thereby modulating the immune evasion tactics employed by tumors and the efficacy of immunotherapeutic interventions. This review delves into the metabolic reprogramming that occurs in tumor cells and a spectrum of immune cells, including T cells, macrophages, dendritic cells, and myeloid-derived suppressor cells (MDSCs), within the TME. The metabolic shifts in these cell types span alterations in glucose, lipid, and amino acid metabolism. Such metabolic reconfigurations can profoundly influence immune cell function and the mechanisms by which tumors evade immune surveillance. Gaining a comprehensive understanding of the metabolic reprogramming of immune cells in the TME is essential for devising novel cancer therapeutic strategies. By targeting the metabolic states of immune cells, it is possible to augment their anti-tumor activities, presenting new opportunities for immunotherapeutic approaches. These strategies hold promise for enhancing treatment outcomes and circumventing the emergence of drug resistance.

ER stress-induced YAP upregulation leads to chondrocyte phenotype loss in age-related osteoarthritis

Background

Osteoarthritis (OA) is a common degenerative joint disease, leading to pain and restricted mobility. Age-related endoplasmic reticulum (ER) stress has been implicated in the pathogenesis of OA, but the underlying mechanisms remain unclear. This study aims to explore the relationship between age-related ER stress, YAP overexpression, and chondrocyte phenotype loss in the development of OA.

Methods

Cartilage samples were collected from patients undergoing amputation, and age-related ER stress markers and YAP expression were assessed using immunohistochemical staining and qPCR. Transgenic mice with cartilage-specific YAP overexpression (YAPOE) were created, and Pamrevlumab was administered to evaluate its therapeutic effects.

Results

Higher expression of ER stress markers and YAP were showed in aged tissues compared to younger tissues. YAP overexpression led to decreased levels of cartilage phenotype markers and increased osteogenesis-related proteins. In vivo, YAPOE mice exhibited OA-like cartilage degeneration, which was mitigated by Pamrevlumab treatment.

Conclusion

Age-related ER stress induces YAP overexpression, contributing to OA pathogenesis. Pamrevlumab effectively prevents this phenotype loss in YAPOE mice, suggesting its potential as a therapeutic agent for OA. These findings provide new insights into the molecular mechanisms of OA and highlight the importance of targeting the ER stress-YAP-CTGF signaling pathway in OA treatment and prevention.

Metabolic regulation of the immune system in health and diseases: mechanisms and interventions

Metabolism, including glycolysis, oxidative phosphorylation, fatty acid oxidation, and other metabolic pathways, impacts the phenotypes and functions of immune cells. The metabolic regulation of the immune system is important in the pathogenesis and progression of numerous diseases, such as cancers, autoimmune diseases and metabolic diseases. The concept of immunometabolism was introduced over a decade ago to elucidate the intricate interplay between metabolism and immunity. The definition of immunometabolism has expanded from chronic low-grade inflammation in metabolic diseases to metabolic reprogramming of immune cells in various diseases. With immunometabolism being proposed and developed, the metabolic regulation of the immune system can be gradually summarized and becomes more and more clearer. In the context of many diseases including cancer, autoimmune diseases, metabolic diseases, and many other disease, metabolic reprogramming occurs in immune cells inducing proinflammatory or anti-inflammatory effects. The phenotypic and functional changes of immune cells caused by metabolic regulation further affect and development of diseases. Based on experimental results, targeting cellular metabolism of immune cells becomes a promising therapy. In this review, we focus on immune cells to introduce their metabolic pathways and metabolic reprogramming, and summarize how these metabolic pathways affect immune effects in the context of diseases. We thoroughly explore targets and treatments based on immunometabolism in existing studies. The challenges of translating experimental results into clinical applications in the field of immunometabolism are also summarized. We believe that a better understanding of immune regulation in health and diseases will improve the management of most diseases.

Crosstalk between macrophages and immunometabolism and their potential roles in tissue repair and regeneration

Immune metabolism is a result of many specific metabolic reactions, such as glycolysis, the tricarboxylic acid (TCA) pathway, the pentose phosphate pathway (PPP), mitochondrial oxidative phosphorylation (OXPHOS), fatty acid oxidation (FAO), fatty acid biosynthesis (FAs) and amino acid pathways, which promote cell proliferation and maintenance with structural and pathological energy to regulate cellular signaling. The metabolism of macrophages produces many metabolic intermediates that play important regulatory roles in tissue repair and regeneration. The metabolic activity of proinflammatory macrophages (M1) mainly depends on glycolysis and the TCA cycle system, but anti-inflammatory macrophages (M2) have intact functions of the TCA cycle, which enhances FAO and is dependent on OXPHOS. However, the metabolic mechanisms of macrophages in tissue repair and regeneration have not been well investigated. Thus, we review how three main metabolic mechanisms of macrophages, glucose metabolism, lipid metabolism, and amino acid metabolism, regulate tissue repair and regeneration.

A new perspective on the therapeutic potential of tumor metastasis: targeting the metabolic interactions between TAMs and tumor cells

Tumor-associated macrophages (TAMs) undergo metabolic reprogramming, encompassing glucose, amino acid, fatty acid metabolism, tricarboxylic acid (TCA) cycle, purine metabolism, and autophagy, within the tumor microenvironment (TME). The metabolic interdependencies between TAMs and tumor cells critically influence macrophage recruitment, differentiation, M2 polarization, and secretion of epithelial-mesenchymal transition (EMT)-related factors, thereby activating intratumoral EMT pathways and enhancing tumor cell invasion and metastasis. Tumor cell metabolic alterations, including hypoxia, metabolite secretion, aerobic metabolism, and autophagy, affect the TME's metabolic landscape, driving macrophage recruitment, differentiation, M2 polarization, and metabolic reprogramming, ultimately facilitating EMT, invasion, and metastasis. Additionally, macrophages can induce tumor cell EMT by reprogramming their aerobic glycolysis. Recent experimental and clinical studies have focused on the metabolic interactions between macrophages and tumor cells to control metastasis and inhibit tumor progression. This review highlights the regulatory role of TAM-tumor cell metabolic codependencies in EMT, offering valuable insights for TAM-targeted therapies in highly metastatic tumors. Modulating the metabolic interplay between tumors and TAMs represents a promising therapeutic strategy for treating patients with metastatic cancers.

XBP1 Facilitating NF-κB-p65 Nuclear Translocation Promotes Macrophage-Originated Sterile Inflammation Via Regulating MT2 Transcription in the Ischemia/Reperfusion Liver

BACKGROUND & AIMS

XBP1, most conserved transcription factor of endoplasmic reticulum stress, plays important roles in physiological and pathologic settings and has profound effects on disease progression and prognosis, so it is necessary to investigate XBP1 in macrophage-originated sterile inflammation during liver ischemia/reperfusion injury (IRI). Macrophage XBP1 expression and liver injury are analyzed in patients undergoing ischemia-related hepatectomy.

METHODS

A myeloid-specific male XBP1-knockout (XBP1M-KO) strain is created for function and mechanism of XBP1 on macrophage-derived sterile inflammation in murine liver IRI with in vitro parallel research. Macrophages cocultured with hypoxia-treated hepatocytes are applied to investigate impact of XBP1 in vitro, with analysis of RNA sequencing and databases.

RESULTS

Clinically, macrophage XBP1 expression significantly increases in ischemic liver tissues and positively correlates with liver injury after hepatectomy. Less hepatocellular damage is presented in XBP1M-KO mice than in XBP1-proficient (XBP1FL/FL) control animals. In vitro, XBP1 deficiency inhibits sterile inflammation and migration in macrophages cocultured with hypoxia-treated hepatocytes. Analysis of RNA sequencing and databases determines Metallothionein 2 (MT2) as XBP1 target gene, negatively regulated by binding with its promoter. XBP1 deficiency increases MT2 and IKBα expression, but inhibits nuclear factor-κB-p65 phosphorylation, markedly neutralizing XBP1M-KO-related benefits by promoting sterile inflammation during liver IRI.

CONCLUSIONS

XBP1 promotes macrophage-originated sterile inflammation, increases liver IRI by binding to MT2 promoter, and regulates MT2/nuclear factor-κB pathway, potentially therapeutic for clinical liver IRI.

Emerging role of Jumonji domain-containing protein D3 in inflammatory diseases

Jumonji domain-containing protein D3 (JMJD3) is a 2-oxoglutarate-dependent dioxygenase that specifically removes transcriptional repression marks di- and tri-methylated groups from lysine 27 on histone 3 (H3K27me2/3). The erasure of these marks leads to the activation of some associated genes, thereby influencing various biological processes, such as development, differentiation, and immune response. However, comprehensive descriptions regarding the relationship between JMJD3 and inflammation are lacking. Here, we provide a comprehensive overview of JMJD3, including its structure, functions, and involvement in inflammatory pathways. In addition, we summarize the evidence supporting JMJD3's role in several inflammatory diseases, as well as the potential therapeutic applications of JMJD3 inhibitors. Additionally, we also discuss the challenges and opportunities associated with investigating the functions of JMJD3 and developing targeted inhibitors and propose feasible solutions to provide valuable insights into the functional exploration and discovery of potential drugs targeting JMJD3 for inflammatory diseases.

Remodeling the hepatic immune microenvironment and demolishing T cell traps to enhance immunotherapy efficacy in liver metastasis

Immune checkpoint inhibitors (ICIs) exhibit compromised therapeutic efficacy in many patients with advanced cancers, particularly those with liver metastases. Much of this incapability can be ascribed as an irresponsiveness resulting from the "cold" hepatic tumor microenvironment that acts as T cell "traps" for which there currently lack countermeasures. We report a novel nanomedicine that converts the hepatic immune microenvironment to a "hot" phenotype by targeting hepatic macrophage-centric T cell elimination. Using the nanomedicine, composed of KIRA6 (an endothelium reticulum stress inhibitor), α-Tocopherol nanoemulsions, and anti-PD1 antibodies, we found its potency in murine models of orthotopic colorectal tumors and hepatic metastases, restoring immune responses and enhancing anti-tumor effects. A post-treatment scrutiny of the immune microenvironment landscape in the liver reveals repolarization of immunosuppressive hepatic macrophages, upregulation of Th1-like effector CD4+ T cells, and rejuvenation of dendritic cells along with CD8+ T cells. These findings suggest adaptations of liver-centric immune milieu modulation strategies to improve the efficacy of ICIs for a variety of "cold" tumors and their liver metastases.

Endoplasmic reticulum stress in diseases

The endoplasmic reticulum (ER) is a key organelle in eukaryotic cells, responsible for a wide range of vital functions, including the modification, folding, and trafficking of proteins, as well as the biosynthesis of lipids and the maintenance of intracellular calcium homeostasis. A variety of factors can disrupt the function of the ER, leading to the aggregation of unfolded and misfolded proteins within its confines and the induction of ER stress. A conserved cascade of signaling events known as the unfolded protein response (UPR) has evolved to relieve the burden within the ER and restore ER homeostasis. However, these processes can culminate in cell death while ER stress is sustained over an extended period and at elevated levels. This review summarizes the potential role of ER stress and the UPR in determining cell fate and function in various diseases, including cardiovascular diseases, neurodegenerative diseases, metabolic diseases, autoimmune diseases, fibrotic diseases, viral infections, and cancer. It also puts forward that the manipulation of this intricate signaling pathway may represent a novel target for drug discovery and innovative therapeutic strategies in the context of human diseases.

ZDHHC9-mediated Bip/GRP78 S-palmitoylation inhibits unfolded protein response and promotes bladder cancer progression

Recent studies have highlighted palmitoylation, a novel protein post-translational modification, as a key player in various signaling pathways that contribute to tumorigenesis and drug resistance. Despite this, its role in bladder cancer (BCa) development remains inadequately understood. In this study, ZDHHC9 emerged as a significantly upregulated oncogene in BCa. Functionally, ZDHHC9 knockdown markedly inhibited tumor proliferation, promoted tumor cell apoptosis, and enhanced the efficacy of gemcitabine (GEM) and cisplatin (CDDP). Mechanistically, SP1 was found to transcriptionally activate ZDHHC9 expression. ZDHHC9 subsequently bound to and palmitoylated the Bip protein at cysteine 420 (Cys420), thereby inhibiting the unfolded protein response (UPR). This palmitoylation at Cys420 enhanced Bip's protein stability and preserved its localization within the endoplasmic reticulum (ER). ZDHHC9 might become a novel therapeutic target for BCa and could also contribute to combination therapy with GEM and CDDP.

Aberrant regulation of serine metabolism drives extracellular vesicle release and cancer progression

Cancer cells secrete extracellular vesicles (EVs) to regulate cells in the tumor microenvironment to benefit their own growth and survive in the patient's body. Although emerging evidence has demonstrated the molecular mechanisms of EV release, regulating cancer-specific EV secretion remains challenging. In this study, we applied a microRNA library to reveal the universal mechanisms of EV secretion from cancer cells. Here, we identified miR-891b and its direct target gene, phosphoserine aminotransferase 1 (PSAT1), which promotes EV secretion through the serine-ceramide synthesis pathway. Inhibition of PSAT1 affected EV secretion in multiple types of cancer, suggesting that the miR-891b/PSAT1 axis shares a common mechanism of EV secretion from cancer cells. Interestingly, aberrant PSAT1 expression also regulated cancer metastasis via EV secretion. Our data link the PSAT1-controlled EV secretion mechanism and cancer metastasis and show the potential of this mechanism as a therapeutic target in multiple types of cancer.

Extracellular vesicles from a novel Lactiplantibacillus plantarum strain suppress inflammation and promote M2 macrophage polarization

Background

Lactiplantibacillus plantarum (L. plantarum) is known for its probiotic properties, including antioxidant and anti-inflammatory effects. Recent studies have highlighted the role of extracellular vesicles (EVs) from prokaryotic cells in anti-inflammatory effects.

Objective

This study aims to investigate the anti-inflammatory effects of extracellular vesicles derived from a newly isolated strain of L. plantarum (LP25 strain) and their role in macrophage polarization.

Methods

The LP25 strain and its extracellular vesicles were isolated and identified through genomic sequencing, transmission electron microscopy (TEM), and nanoparticle tracking analysis (NTA). RAW 264.7 cells were treated with lipopolysaccharide (LPS) and/or LP25-derived extracellular vesicles (LEV). Morphological changes in the cells were observed, and the expression levels of pro-inflammatory cytokines (TNF-α, IL-6)、iNOS and anti-inflammatory cytokines (IL-10) 、Arg-1 were measured using quantitative real-time PCR (qPCR). Flow cytometry was used to detect the expression of Arg-1 in the treated cells.

Results

Treatment with LP25 EVs led to significant morphological changes in RAW 264.7 cells exposed to LPS. LP25 EVs treatment resulted in increased expression of Arg-1 and anti-inflammatory cytokines IL-10, and decreased expression of iNOS and surface markers protein CD86. Flow cytometry confirmed the increased expression of the M2 macrophage marker Arg-1 in the LP25 EVs-treated group.

Conclusion

Extracellular vesicles from Lactiplantibacillus plantarum LP25 can suppress inflammatory responses and promote the polarization of macrophages toward the anti-inflammatory M2 phenotype. These findings provide new evidence supporting the anti-inflammatory activity of L. plantarum-derived EVs.