Danger Signals Research Articles

IR813-Induced Photothermal Therapy: Leveraging Immunogenic Cell Death for Cancer Treatment

Background: Photothermal therapy has the potential to enhance the precision and safety of oncological treatments. However, applicable photothermal agents associated with its photothermal activated immunogenic cell death remain exploiting. Methods: This study evaluates the effectiveness of IR813, a photothermal agent, combined with near-infrared (NIR) light for cancer treatment. In vitro, 4T1 cancer cells were treated with IR813 (5 μg/mL) and exposed to NIR irradiation (1 W/cm2) for 5 min. In vivo, after the tumor-bearing mice administered with IR813 (1 mg/kg) and exposed to NIR irradiation (1 W/cm2) for 10 min, the tumor volume, survival and immune activation were evaluated. Results: IR813 significantly increased the cytotoxicity of 4T1 cancer cells following near-infrared irradiation, resulting in the release of damage-associated molecular patterns and immunogenic cell death. Specifically, the cell viability was reduced to 5% compared to the control group. In vivo, irradiating the accumulation of IR813 at the tumor site had the potential to mediate substantial photothermal tumor suppression, improved mouse survival, and reduced metastasis, with minimal adverse reactions. Furthermore, the immune responses stimulated by IR813-induced photothermal therapy were evidenced by increased mature dendritic cell and cytotoxic T lymphocyte counts and a decrease in regulatory T cells in the spleen, tumor, and lymph nodes. Conclusions: These findings suggest that IR813-induced photothermal therapy is a promising approach for enhancing immunotherapy, directly inhibiting tumors while boosting systemic anti-cancer immunity.

Photosensitive Hybrid γδ-T Exosomes for Targeted Cancer Photoimmunotherapy.

Melanoma is the most aggressive type of skin cancers. Traditional chemotherapy and radiotherapy have limited effectiveness and can lead to systemic side effects. Photodynamic therapy (PDT) is a photoresponsive cancer therapy based on photosensitizers to generate reactive oxygen species (ROS) to eradicate tumor cells. Our previous study showed that exosomes derived from human γδ-T cells (γδ-T exosomes) could control Epstein-Barr virus-associated tumors. Here, we combined γδ-T exosomes and PDT for targeted photoimmunotherapy by membrane fusion of γδ-T exosomes and Chlorin e6 (Ce6)-loaded liposomes. The functional surface proteins, such as CCR5 and PD-1, on the hybrid exosomes mediated the specific binding of hybrid exosomes toward melanoma tissues. The cytolytic molecules, such as granzyme A, granzyme B, perforin, and granulysin from γδ-T exosomes, induced specific apoptosis of cancer cells without harming normal cells. In response to light irradiation, ROS generation inside melanoma cells synergized with cytolytic molecules to induce apoptosis and promote immunogenic cancer cell death (ICD). The subsequently released damage-associated molecular patterns (DAMPs) could stimulate human dendritic cell maturation and induce melanoma antigen-specific CD4+ and CD8+ T-cell responses, thereby enhancing antitumor immunity. This study provides a promising strategy by combining γδ-T exosomes and PDT for photoimmunotherapy, thereby expanding the clinical applications of γδ-T exosome therapy for cancer patients.

Targeted Delivery of SmacN7 Peptide Induces Immunogenic Cell Death in Cervical Cancer Treatment.

Cervical cancer is a common tumor in women and one of the common causes of cancer death in women. Due to the aggressive and non-specific nature of traditional chemotherapy, there is a growing need for new treatment modalities. Currently, tumor immunotherapy is increasingly garnering attention as a disruptive treatment approach. Therefore, we constructed CCTP-SmacN7, a delivery system capable of releasing active molecules in the tumor microenvironment. CCTP-SmacN7 can not only inhibit tumor proliferation and migration, but also induce tumors to produce large amounts of reactive oxygen species. The production of reactive oxygen species can activate tumors to release or expose damage-associated molecular patterns, promote DC cell maturation, and ultimately activate T cells. Here, we present an innovative targeted treatment approach for cervical cancer. While inducing tumor immunogenic cell death, this program can also improve the tumor microenvironment and initiate the tumor immune cycle.

Oxidative and nitrative DNA damage induced by industrial chemicals in relation to carcinogenesis.

Many chemicals have been used for industrial purposes, and some of them are carcinogenic to humans. However, their molecular mechanisms have not been well understood. Reactive oxygen species are generated from industrial chemicals and contribute to carcinogenesis. Particles and fibers are accumulated in respiratory systems by inhalation exposure and cause chronic inflammation. Under inflammatory conditions, reactive nitrogen species are generated from inflammatory and epithelial cells. These species cause oxidative and nitrative DNA damage, leading to carcinogenesis. We carried out experiments on DNA damage induced by various industrial chemicals and investigated their molecular mechanisms. We examined oxidative DNA damage induced by industrial chemicals using DNA fragments derived from human cancer-relevant genes by polyacrylamide gel electrophoresis. We also examined the formation of 8-nitroguanine (8-nitroG), a DNA lesion formed under inflammatory conditions, in lung tissues and cultured cells exposed to industrial chemicals by immunohistochemistry and immunocytochemistry. Benzene and o-toluidine metabolites caused oxidative damage to DNA fragments in the presence of Cu(II). H2O2 and Cu(I) were generated during oxidation of these chemicals and involved in DNA damage. 8-NitroG formation was observed in lung tissues of asbestos-exposed mice and humans. Carbon nanomaterials and indium compounds induced 8-nitroG formation in human lung epithelial cells via the release of damage-associated molecular patterns from exposed cells. Various industrial chemicals are considered to induce carcinogenesis by causing oxidative and nitrative DNA damage. These findings would provide an insight into risk assessment of industrial chemicals and prevention of carcinogenesis that occurs in workplaces.

Simultaneous Induction of Immunogenic Pyroptosis and PD-L1 Downregulation by One Single Photosensitizer for Synergistic Cancer Photoimmunotherapy.

Pyroptosis, an excellent form of immunogenic cell death that can effectively activate antitumor immune responses, is attracting considerable interest as a promising approach for cancer immunotherapy. Immunogenic pyroptosis can recruit and stimulate dendritic cells to provoke further activation and tumor infiltration of T cells by releasing danger-associated molecular patterns, thus improving the tumor response to PD-1/PD-L1 checkpoint blockade immunotherapy. Here, we report the discovery of a bifunctional photosensitizer Nile Violet that can simultaneously trigger caspase-3/GSDME-mediated immunogenic pyroptosis and PD-L1 downregulation for cancer photoimmunotherapy. It was shown that this synergistic therapeutic strategy significantly inhibited tumor growth by triggering a systemic antitumor immune response. This work highlights the potential of inducing immunogenic pyroptosis and PD-L1 downregulation for synergistic tumor ablation via a single agent.

Allergen-induced activation of epithelial P2Y2 receptors promotes ATP exocytosis and type 2 immunity in airways.

Environmental allergens induce the release of danger signals from the airway epithelium that trigger type 2 immune responses and promote airway inflammation. To investigate the role of allergen-stimulated P2Y2 receptor activation in regulating ATP, IL-33 and DNA release by human bronchial epithelial (hBE) cells and mouse airways. hBE cells were exposed to Alternaria alternata extract and secretion of ATP, IL-33 and DNA were studied in vitro. Molecular and cellular mechanisms were examined by biochemical and genetic approaches. Mice were treated intranasally (i.n.) with pharmacologic agents and exposed to Alternaria extract. Exposure of hBE cells to Alternaria extract stimulated P2Y2 receptors coupled to phospholipase Cβ3, leading to activation of multiple PKC isoforms and an increase in intracellular Ca2+ concentration. Small interfering RNAs (siRNAs) targeting PKCδ or inhibiting PKCδ activity with delcasertib blocked exocytosis of ATP and reduced IL-33 and DNA secretion. Moreover, a peptide antagonist for MARCKS reduced vesicular ATP release. A proximity ligand assay showed that Alternaria extract stimulated MARCKS desorption from the plasma membrane and delcasertib prevented the response. Finally, the P2Y2 receptor antagonist AR-C118925XX and delcasertib blocked IL-33, DNA and type 2 cytokine secretion in vivo in mice exposed to Alternaria. P2Y2 receptor stimulation following allergen exposure promoted activation of PLCβ3, PKCδ and MARCKS protein desorption from the apical membrane, which facilitated ATP exocytosis and subsequent secretion of IL-33 and DNA. Epithelial P2Y2 receptors serve as primary sensors for aeroallergen-induced alarmin release by airway epithelial cells.

P0065 Circulating cell-free DNA and mitochondrial DNA differentiate disease activity in paediatric-onset inflammatory bowel disease: Interim analysis from Scotland-wide Mini-MUSIC study (2020-26)

Abstract Background Mitochondrial dysfunction has been implicated in the pathogenesis of inflammatory bowel disease (IBD) particularly paediatric-onset IBD (PIBD).1,2 Circulating cell-free DNA (cfDNA) and mitochondrial DNA (mtDNA) are damage-associated molecular patterns (DAMPS) released into the bloodstream during tissue damage and cell death and can be detected in peripheral blood samples.3 Recent studies have suggested that levels of cfDNA and mtDNA may correlate with disease activity in adult IBD4 but their utility in paediatric populations remains unexplored. This study aims to present initial data on the potential use of cfDNA and mtDNA as biomarkers in PIBD. Methods Mini-MUSIC and GI-DAMPS are ongoing longitudinal and cross-sectional multi-centre translational research studies in Scotland (2020 – 2026) with a primary aim of investigating the inflammatory mechanisms of IBD with a focus on multi-omics, immune- and microbiome-profiling aligned to prospective clinical follow-up. We measured circulating cfDNA (GAPDH) and mtDNA (ND2), using digital droplet PCR, in the peripheral blood of patients diagnosed under 17 years of age (A1 phenotype) and correlated this with phenotypic data and disease activity scores. Results Sixty-five A1 patients were included (39/65 (60%) male; 51 Crohn’s disease (CD), 6 ulcerative colitis (UC), 1 inflammatory bowel disease unclassified (IBDU) and 7 symptomatic non-IBD controls) with a median (IQR) age at diagnosis of 13 (10.0-15.0) years. mtDNA levels were significantly higher in those with highly active disease compared to those in remission (median [IQR] 145.1 (89.5-673.7 ng/μl) vs 64.4 (24.3-167.5 ng/μl), p=0.008) and compared to non-IBD symptomatic controls (median [IQR] 145.1 (89.5-673.7 ng/μl) vs 28.8 (12.6 – 138.7 ng/μl), p=0.036). Circulating cell-free DNA levels were significantly higher in those with highly active disease than non-IBD controls (4.94 (1.1-9.9 ng/ul) vs median [IQR] 0.53 (0.0-1.4 ng/ul), p=0.017). mtDNA levels were positively correlated with endoscopic disease activity (SES-CD) in Crohn’s disease (Pearson r=0.7619, p=0.004). Conclusion Our initial data from ongoing work, demonstrate that the levels of cfDNA and mtDNA in the blood are potentially valuable biomarkers for differentiating disease activity in PIBD and to identify PIBD-patients where mitochondrial dysfunction is dominant and thereby with the potential to stratify future human mechanistic studies and mitochondrial-targeted therapies.

Multi-pathway oxidative stress amplification via controllably targeted nanomaterials for photoimmunotherapy of tumors

Photoimmunotherapy, which combines phototherapy with immunotherapy, exhibits significantly improved therapeutic effects compared with mono-treatment regimens. However, its use is associated with drawbacks, such as insufficient reactive oxygen species (ROS) production and uneven photosensitizer distribution. To address these issues, we developed a controllable, targeted nanosystem that enhances oxidative stress through multiple pathways, achieving synergistic photothermal, photodynamic, and immunotherapy effects for tumor treatment. These nanoparticles (D/I@HST NPs) accurately target overexpressed transferrin receptors (TfRs) on the surface of tumor cells through surface-modified transferrin (Tf). After endocytosis, D/I@HST NPs generate ROS under 808-nm laser irradiation, breaking the ROS-responsive crosslinking agent and increasing drug release and utilization. Tf also carries Fe3+, which is reduced to Fe2+ by iron reductase in the acidic tumor microenvironment (TME). Consequently, the endoperoxide bridge structure in dihydroartemisinin is cleaved, causing additional ROS generation. Furthermore, the released IR-780 exerts both photodynamic and photothermal effects, enhancing tumor cell death. This multi-pathway oxidative stress amplification and photothermal effect can trigger immunogenic cell death in tumors, promoting the release of relevant antigens and damage-associated molecular patterns, thereby increasing dendritic cell maturation and sensitivity of tumor cells to immunotherapy. Mature dendritic cells transmit signals to T cells, increasing T cells infiltration and activation, facilitating tumor growth inhibition and the suppression of lung metastasis. Furthermore, the myeloid-derived suppressor cells in the tumor decreases significantly after treatment. In summary, this multi-pathway oxidative stress-amplified targeted nanosystem effectively inhibits tumors, reverses the immunosuppressive tumor microenvironment, and provides new insights into tumor immunotherapy combined with phototherapy.

P0105 Evaluation of Stimuli Driving Oncostatin M Expression in Bone Marrow-Derived Macrophages

Abstract Background Oncostatin M (OSM) is a cytokine linked to inflammatory diseases, including inflammatory bowel disease (IBD), where it contributes to inflammation, tissue remodeling, and fibrosis. Despite its established role, the specific signals driving OSM expression in colitis remain unclear. Methods Bone marrow-derived macrophages (BMDMs) were differentiated using M-CSF and stimulated for 36 hours with a range of Toll-like receptor (TLR) agonists, damage-associated molecular patterns (DAMPs), cytokines, and bacterial lysates. OSM secretion was quantified using enzyme-linked immunosorbent assays (ELISA). To dissect key signaling pathways, we applied chemical inhibitors and utilized macrophages derived from gene-deficient mice. Results Myd88-dependent stimuli, including TLR1/2 (Pam3CSK4), TLR4 (LPS), TLR2/6 (FSL-1), TLR7/8 (R848), IL-1α, and IL-33, significantly increased OSM expression in BMDMs. Gram-negative (E. coli, C. rodentium) and Gram-positive (S. aureus) bacterial lysates also enhanced OSM secretion. Pro-inflammatory cytokine IFN-γ further boosted OSM levels, consistent with in vivo findings of OSM upregulation in inflammatory monocytes. Additionally, IL-4, which induces a tissue repair phenotype in macrophages, markedly increased OSM secretion. Conclusion OSM expression in BMDMs is driven by multiple signaling pathways, indicating a synergistic effect of diverse stimuli. Identifying key stimulatory and inhibitory molecules, alongside macrophage-specific knockout analyses, will help clarify the upstream regulators of OSM. Understanding these drivers may uncover new therapeutic targets in IBD and offer insights into the onset of fibrotic processes.

Role of astrocytes connexins - pannexins in acute brain injury.

Acute brain injuries (ABIs) encompass a broad spectrum of primary injuries such as ischemia, hypoxia, trauma, and hemorrhage that converge into secondary injury where some mechanisms show common determinants. In this regard, astroglial connexin and pannexin channels have been shown to play an important role. These channels are transmembrane proteins sharing similar topology and form gateways between adjacent cells named gap junctions (GJs) and pores into unopposed membranes named hemichannels (HCs). In astrocytes, GJs and HCs enable intercellular communication and have active participation in normal brain physiological processes, such as calcium waves, synapsis modulation, regional blood flow regulation, and homeostatic control of the extracellular environment, among others. However, after acute brain injury, astrocytes can change their phenotype and modify the activity of both channels and hemichannels, which can result in the amplification of danger signals, increased mediators of inflammation, and neuronal death, contributing to the expansion of brain damage and neurological deterioration. This is known as secondary brain damage. In this review, we discussed the main biological mechanism of secondary brain damage with a particular focus on astroglial connexin and pannexin participation during acute brain injuries.

Extracellular ATP regulates phagocytic activity, mitochondrial respiration, and cytokine secretion of human astrocytic cells.

The two main glial cell types of the central nervous system (CNS), astrocytes and microglia, are responsible for neuroimmune homeostasis. Recent evidence indicates astrocytes can participate in removal of pathological structures by becoming phagocytic under conditions of neurodegenerative disease when microglia, the professional phagocytes, are impaired. We hypothesized that adenosine triphosphate (ATP), which acts as damage-associated molecular pattern (DAMP), when released at high concentrations into extracellular space, upregulates phagocytic activity of human astrocytes. This study is the first to measure changes in phagocytic activity and mitochondrial respiration of human astrocytic cells in response to extracellular ATP. We demonstrate that ATP-induced phagocytic activity of U118 MG astrocytic cells is accompanied by upregulated mitochondrial oxidative phosphorylation, which likely supports this energy-dependent process. Application of a selective antagonist A438079 provides evidence identifying astrocytic purinergic P2X7 receptor (P2X7R) as the potential regulator of their phagocytic function. We also report a rapid ATP-induced increase in intracellular calcium ([Ca2+]i), which could serve as regulator of both the phagocytic activity and mitochondrial metabolism, but this hypothesis will need to be tested in future studies. Since ATP upregulates interleukin (IL)-8 secretion by astrocytes but has no effect on their cytotoxicity towards neuronal cells, we conclude that extracellular ATP affects only specific functions of astrocytes. The selectivity of P2X7R-dependent regulation of astrocyte functions by extracellular ATP could allow targeting this receptor-ligand interaction to upregulate their phagocytic function. This could have beneficial outcomes in neurodegenerative disorders, such as Alzheimer's disease, that are characterized by reactive astrocytes and defective phagocytic processes.

Lung seven transmembrane receptors are involved in Arabidopsis root growth mediated by Danger-associated peptide Pep1.

Lung seven transmembrane receptor family is a small part of Arabidopsis gene family. So far, the function of some members of the this family is unknown. Plant elicitor peptide1 (Pep1) is one of damage-associated molecular patterns (DAMPs), which could trigger root growth inhibition and plant immunity responses. Here, we identified members of the Lung seven transmembrane family, and proved they are important for Pep1-induced root growth and development. We found that the expression levels of 7TM2 and 7TM6 were elevated in wild-type treated with Pep1. Phenotypic analysis showed that the growth phenotypes of 7tm2 and 7tm6 were similar to the wild-type under Pep1 treatment, but the 7tm2 7tm6 had a Pep1 hypersensitivity phenotype compared to wild-type. Furthermore, the complementation lines were able to restore the Pep1 phenotype of 7tm2 7tm6 to that similar to wild-type. These results suggest that 7TM2 and 7TM6 are involved in the regulation of root growth by Pep1. This study revealed the new functions of the Lung seven transmembrane receptor family and provided new ideas for further revealing the molecular mechanism of Pep1-regulated root growth and development.

Type 2 conventional dendritic cell functional heterogeneity: ontogenically committed or environmentally plastic?

Conventional dendritic cells (cDCs) are sentinels of the mammalian immune system that sense a wide range of danger and homeostatic signals to induce appropriately targeted T cell immune responses. Traditionally classified into two main subsets, cDC1 and cDC2, recent research shows that cDC2s exhibit significant heterogeneity and can be further subdivided. Studies in mice and humans show that, beyond their ontogeny, cDC2s acquire dynamic and tissue-specific characteristics that are influenced by local environmental signals, which impact on their functions during homeostasis, inflammation, and infection. The novel concept is proposed that tissue-derived signals and tissue plasticity can override preestablished developmental programming, thereby redefining developmental trajectories and cDC2 functionality. Ultimately, understanding cDC2 heterogeneity and plasticity has important implications for modulating T cell immunity in health and disease.

Mechanisms of Lipid-Associated Macrophage Accrual in Metabolically Stressed Adipose Tissue.

Adipose tissue (AT) inflammation, a hallmark of the metabolic syndrome, is triggered by overburdened adipocytes sending out immune cell recruitment signals during obesity development. An AT immune landscape persistent throughout weight loss and regain constitutes an immune-obesogenic memory that hinders long-term weight loss management. Lipid-associated macrophages (LAMs) are emerging as major players in diseased, inflamed metabolic tissues and may be key contributors to an obesogenic memory in AT. Our previous study found that LAM abundance increases with weight loss via intermittent fasting (IF) in obese mice, which is driven by adipocyte p53 signalling. However, the specific signals causing LAM accumulation in AT under IF remain unknown. In this piece, we hypothesise on a range of adipocyte-secreted signals that can harbor immune-attractive features upon fasting/refeeding cycles. We highlight possible mechanisms including cell death signalling, matrikines, and other damage-associated molecular patterns (DAMPs), as well as adipo(-cyto)kines, lipid mediators, metabolites, extracellular vesicles, and epigenetic rewiring. Finally, we consider how advances in mechanisms of AT LAM recruitment gleaned from preclinical models might be translatable to long-term weight management in humans. Thus, we provide vantage points to study signals driving monocyte recruitment, polarisation towards LAMs, and LAM retention, to harness the therapeutic potential of modulating AT LAM levels by impacting the immune-obesogenic memory in metabolic disease.

Lymphatic platelet thrombosis limits bone repair by precluding lymphatic transporting DAMPs

In the musculoskeletal system, lymphatic vessels (LVs), which are interdigitated with blood vessels, travel and form an extensive transport network. Blood vessels in bone regulate osteogenesis and hematopoiesis, however, whether LVs in bone affect fracture healing is unclear. Here, we investigate the lymphatic draining function at the tibial fracture sites using near-infrared indocyanine green lymphatic imaging (NIR-ICG) and discover that lymphatic drainage insufficiency (LDI) starts on day one and persists for up to two weeks following the fracture in male mice. Sufficient lymphatic drainage facilitates fracture healing in male mice. Furthermore, we identify that lymphatic platelet thrombosis (LPT) blocks the draining lymphoid sinus and LVs, causes LDI, and inhibits fracture healing in male mice, which can be rescued by a blood thinner. Moreover, unblocked lymphatic drainage decreases neutrophils and increases M2-type macrophages of the hematoma niche to support osteoblast (OB) survival and bone marrow-derived mesenchymal stem cell (BMSC) proliferation via transporting damage-associated molecular patterns (DAMPs) in male rats. Lymphatic platelet thrombolysis also benefits senile fracture healing in female mice. These findings demonstrate that LPT limits bone regeneration by impeding lymphatic transporting DAMPs. Together, these findings represent a way forward in the treatment of bone repair.

The actin cytoskeleton regulates danger-associated molecular pattern signaling and PEP1 RECEPTOR1 internalization.

In plants, cytoskeletal proteins assemble into dynamic polymers that play numerous roles in diverse fundamental cellular processes, including endocytosis, vesicle trafficking, and the spatial distribution of organelles and protein complexes. Plant elicitor peptides (Peps) are damage/danger-associated molecular patterns (DAMPs) that are perceived by the receptor-like kinases PEP RECEPTOR 1 (PEPR1) and PEPR2 to enhance innate immunity and inhibit root growth in Arabidopsis (Arabidopsis thaliana). To date, however, there is little evidence that the actin cytoskeleton of the host cell participates in DAMP-induced innate immunity. Here, we demonstrated that the actin cytoskeleton alters the Pep1-triggered immune response. In addition, dual-color total internal reflection fluorescence-structured illumination microscopy (TIRF-SIM) showed that PEPR1 diffusion on the plasma membrane is closely related to the actin cytoskeleton. We performed single-particle tracking to quantify individual protein particles and found that the actin cytoskeleton notably regulates PEPR1 mobility and cluster size. More importantly, we demonstrated that actin filament reconfiguration is sufficient to inhibit Pep1-induced internalization, which alters the immune response. Taken together, these findings suggest that the actin cytoskeleton functions as an integration node for Pep1 signaling and PEPR1 endocytosis.

Reactive Metabolites Cause Idiosyncratic Drug-Induced Liver Injury via Inflammasome Activation in Antigen-Presenting Cells.

Although the pathophysiology of idiosyncratic drug-induced liver injury (IDILI) is unclear, it is presumed to be immune-mediated, involving complex interactions between drug metabolism and activation of the immune system. The following four reactive metabolite production patterns are considered: (1) parent compounds into reactive metabolites within neutrophils or antigen-presenting cells (APCs), (2) reactive metabolites produced by cytochrome P450 (CYP), (3) nonreactive metabolites produced by CYP into reactive metabolites within APCs, and (4) reactive metabolites produced by non-CYPs. Reactive metabolites indirectly activate inflammasomes in APCs, leading to IDILIs. These metabolites can cause cell damage, resulting in the release of damage-associated molecular patterns (DAMPs), which subsequently activate APCs. Given the diversity of DAMPs, comprehensive analyses are warranted to identify additional candidates. If validates, these DAMPs could be used as early biomarkers and predictive markers of IDILIs onset.

Extracellular peroxiredoxin 6 released from alveolar epithelial cells as a DAMP drives macrophage activation and inflammatory exacerbation in acute lung injury.

Acute respiratory distress syndrome (ARDS) is featured with acute lung inflammatory injury. Our prospective study found that higher levels of peroxiredoxin 6(PRDX6) were detected in bronchoalveolar lavage (BAL) fluid from ARDS patients. Elevated PRDX6 was also correlated with monocytic activation and poor prognosis in ARDS patients. To investigate the origin of extracellular PRDX6, we conducted in vitro and in vivo experiments, demonstrating that PRDX6 can be actively released from alveolar epithelial cells under stress conditions. Our study demonstrated that it could be released from injured lung epithelial cells into the bronchoalveolar interstitial space in mice with acute lung injury and in vitro experiments. Moreover, exogenous PRDX6 was shown to activate the TLR4/NF-κB signalling pathway and induce M1 polarization of macrophages. Notably, the inflammatory effects of PRDX6 were mitigated by specific inhibition of the TLR4 (Toll-like receptor 4)-MD2 (Myeloid differentiation factor 2) complex. Using molecular docking simulations and in vitro binding assays, we confirmed a direct interaction between PRDX6 and MD2, further supporting its role as a damage-associated molecular patterns (DAMP) in ARDS. Our findings suggest that extracellular PRDX6 in bronchoalveolar lavage fluid could be a new DAMP factor in ALI, providing new insights into the pathogenesis of secondary hit in ALI/ARDS and highlighting PRDX6 as a potential therapeutic target for mitigating lung inflammation.

An Albumin-Photosensitizer Supramolecular Assembly with Type I ROS-Induced Multifaceted Tumor Cell Deaths for Photodynamic Immunotherapy.

Photodynamic therapy holds great potentials in cancer treatment, yet its effectiveness in hypoxic solid tumor is limited by the oxygen-dependence and insufficient oxidative potential of conventional type II reactive oxygen species (ROS). Herein, the study reports a supramolecular photosensitizer, BSA@TPE-BT-SCT NPs, through encapsulating aggregation-enhanced emission photosensitizer by bovine serum albumin (BSA) to significantly enhance ROS, particularly less oxygen-dependent type I ROS for photodynamic immunotherapy. The abundant type I ROS generated by BSA@TPE-BT-SCT NPs induce multiple forms of programmed cell death, including apoptosis, pyroptosis, and ferroptosis. These multifaceted cell deaths synergistically facilitate the release of damage-associated molecular patterns and antitumor cytokines, thereby provoking robust antitumor immunity. Both in vitro and in vivo experiments confirmed that BSA@TPE-BT-SCT NPs elicited the immunogenic cell death, enhance dendritic cell maturation, activate T cell, and reduce myeloid-derived suppressor cells, leading to the inhibition of both primary and distant tumors. Additionally, BSA@TPE-BT-SCP NPs also exhibited excellent antitumor performance in a humanized mice model, evidenced by a reduction in senescent T cells among these activated T cells. The findings advance the development of robust type I photosensitizers and unveil the important role of type I ROS in enhancing multifaceted tumor cell deaths and antitumor immunogenicity.

Mechanisms of mitochondrial damage-associated molecular patterns associated with inflammatory response in cardiovascular diseases.

Cardiovascular diseases (CVDs) continue to be a substantial global healthcare burden despite considerable progress in therapies. The inflammatory response during the progression of CVD has attracted considerable attention. Mitochondria serve as the principal energy source for the heart. In cardiovascular illnesses, mitochondrial homeostasis is disrupted, accompanied by structural and functional impairments. During mitochondrial stress or injury, mitochondrial damage-associated molecular patterns (mtDAMPs), such as mitochondrial DNA, cardiolipin, N-formyl peptide, and adenosine triphosphate, are released to activate pattern recognition receptors and trigger immunological responses. Inflammatory responses mediated by mtDAMPs substantially contribute to the pathophysiology of cardiovascular illnesses. In this review, we discuss the molecular mechanisms by which different mtDAMPs control the inflammatory response, address the pathological consequences of mtDAMPs in inducing or exacerbating the inflammatory response in CVDs, and summarize potential therapeutic targets in relevant experimental studies. Preventing or reducing mtDAMP release may play a role in CVD progression by alleviating the inflammatory response.