Tetrachlorobenzoquinone exhibits immunotoxicity by inducing neutrophil extracellular traps through a mechanism involving ROS-JNK-NOX2 positive feedback loop

Dihydrophenanthropyrans derived from the pseudobulbs of Pholidota chinensis alleviates neutrophilic inflammation by inhibiting MAPKs and calcium

Five dihydrophenanthropyrans (1-5) were isolated from the pseudobulbs of Pholidota chinensis, among which 1,3-di(4'-hydroxybenzy)-imbricatin (3) was isolated from the nature for the first time. Their structures were elucidated and established through various spectroscopic methods. These compounds exhibited a potent inhibition effect on both N-formyl-methionyl-leucyl-phenylalanine (fMLF)-induced superoxide anion generation and elastase release with IC50 values ranging from 0.23 to 7.63 μM. Furthermore, dihydrophenanthropyrans (1-3) also demonstrated a dose-dependent reactive oxygen species (ROS) scavenging effect. In addition, dihydrophenanthropyrans (2-3) exhibited a dose-dependent reduction in the intracellular Ca2+ concentration ([Ca2+]i) in fMLF-activated human neutrophils. Moreover, dihydrophenanthropyrans (1-3) selectively inhibited the phosphorylation of c-Jun N-terminal kinases (JNKs) and p38, while only dihydrophenanthropyran (1) inhibited the phosphorylation of extracellular signal-regulated kinases (ERKs) in fMLF-activated human neutrophils. Notably, dihydrophenanthropyrans (1-3) did not affect protein kinase B (AKT) activity in these cells. These findings highlight the potent anti-inflammatory capabilities of dihydrophenanthropyrans, manifested through their ability to inhibit superoxide anion generation, suppress elastase release, and selectively modulate key signaling pathways in human neutrophils. This suggests that dihydrophenanthropyrans hold significant promise as therapeutic agents for conditions associated with neutrophil-mediated inflammation.

Drug conjugates for the treatment of lung cancer: from drug discovery to clinical practice

A drug conjugate consists of a cytotoxic drug bound via a linker to a targeted ligand, allowing the targeted delivery of the drug to one or more tumor sites. This approach simultaneously reduces drug toxicity and increases efficacy, with a powerful combination of efficient killing and precise targeting. Antibody‒drug conjugates (ADCs) are the best-known type of drug conjugate, combining the specificity of antibodies with the cytotoxicity of chemotherapeutic drugs to reduce adverse reactions by preferentially targeting the payload to the tumor. The structure of ADCs has also provided inspiration for the development of additional drug conjugates. In recent years, drug conjugates such as ADCs, peptide‒drug conjugates (PDCs) and radionuclide drug conjugates (RDCs) have been approved by the Food and Drug Administration (FDA). The scope and application of drug conjugates have been expanding, including combination therapy and precise drug delivery, and a variety of new conjugation technology concepts have emerged. Additionally, new conjugation technology-based drugs have been developed in industry. In addition to chemotherapy, targeted therapy and immunotherapy, drug conjugate therapy has undergone continuous development and made significant progress in treating lung cancer in recent years, offering a promising strategy for the treatment of this disease. In this review, we discuss recent advances in the use of drug conjugates for lung cancer treatment, including structure-based drug design, mechanisms of action, clinical trials, and side effects. Furthermore, challenges, potential approaches and future prospects are presented.

Insight into the mechanism of melatonin in attenuating PCB126-induced liver injury: Resistance to ROS-dependent NETs formation to alleviate inflammation and lipid metabolism dysfunction

3,3',4',4',5-Polychlorinated biphenyls (PCB126) is classified as a persistent organic environmental pollutant that can cause liver damage by producing excessive reactive oxygen species (ROS). ROS also can stimulate neutrophil extracellular traps (NETs) formation, which cause damage to organism if NETs are produced in excess. Melatonin is generally considered to possess strong antioxidant and anti-inflammation prosperities, but it is unclear whether it can alleviate PCB126-induced injury. To explore whether PCB126-induced liver injury is related to the formation of NETs and whether melatonin has a potent protective effect, we established PCB126 exposure/ PCB126 and melatonin co-treatment mouse models by gavage. To further clarify the specific mechanism, we also cultured neutrophils and AML12 cells to replicate in vivo model. Here, we found PCB126 exposure resulted in an elevation in the activities of MDA, LPO, PCO, and 8-OHdG, and a reduction in the activities of CAT, GSH-PX and SOD. We found that PCB126 exposure led to an elevation in the expression levels of chemokines (CCL2, CCL3, CCL4, CXCL12, and CXCL8) and marker factors for NETs formation (MPO, NE, NOX2, PKCα, and PKCζ) in the PCB126 group. IF, SYTOX staining, and SEM results also revealed that PCB126 could stimulate NETs formation. In addition, results of a co-culture system of PBNs and AML12 cells revealed that the expression levels of inflammatory cytokines (IL-1β, IL-6, and TNF-α) significantly decreased and the expression levels of metabolism factors (Fas, Acc, and Srebp) slightly decreased for scavenging NETs, indicating NETs formation aggravated PCB126-induced hepatic damages. Noteworthy, treatment with melatonin reversed these results. In summary, our findings revealed that melatonin alleviated hepatic damage aggravated by PCB126-induced ROS-dependent NETs formation through suppressing excessive ROS production. This finding not only enriches toxicological mechanism of PCB126, but more importantly extends biological effects of melatonin and its potential application values.

ROS regulation in gliomas: implications for treatment strategies

Gliomas are one of the most common primary malignant tumours of the central nervous system (CNS), of which glioblastomas (GBMs) are the most common and destructive type. The glioma tumour microenvironment (TME) has unique characteristics, such as hypoxia, the blood-brain barrier (BBB), reactive oxygen species (ROS) and tumour neovascularization. Therefore, the traditional treatment effect is limited. As cellular oxidative metabolites, ROS not only promote the occurrence and development of gliomas but also affect immune cells in the immune microenvironment. In contrast, either too high or too low ROS levels are detrimental to the survival of glioma cells, which indicates the threshold of ROS. Therefore, an in-depth understanding of the mechanisms of ROS production and scavenging, the threshold of ROS, and the role of ROS in the glioma TME can provide new methods and strategies for glioma treatment. Current methods to increase ROS include photodynamic therapy (PDT), sonodynamic therapy (SDT), and chemodynamic therapy (CDT), etc., and methods to eliminate ROS include the ingestion of antioxidants. Increasing/scavenging ROS is potentially applicable treatment, and further studies will help to provide more effective strategies for glioma treatment.

Protective effect of vitamin C against tetrachlorobenzoquinone-induced 5-hydroxymethylation-dependent apoptosis in HepG2 cells mainly via the mitochondrial apoptosis pathway

Tetrachlorobenzoquinone (TCBQ) is an active metabolite of pentachlorophenol, and stimulates the accumulation of ROS to trigger apoptosis. The preventive effect of vitamin C (Vc) against TCBQ-induced apoptosis in HepG2 cells is unknown. And there is little known about TCBQ-triggered 5-hydromethylcytosine (5hmC)-dependent apoptosis. Here, we confirmed that Vc alleviated TCBQ-induced apoptosis. Through investigating the underlying mechanism, we found TCBQ downregulated 5hmC levels of genomic DNA in a Tet-dependent manner, with a particularly pronounced decrease in the promoter region, using UHPLC-MS-MS analysis and hydroxymethylated DNA immunoprecipitation sequencing. Notably, TCBQ exposure resulted in alterations of 5hmC abundance to ∼91% of key genes at promoters in the mitochondrial apoptosis pathway, along with changes of mRNA expression in 87% of genes. By contrast, 5hmC abundance of genes only exhibited slight changes in the death receptor/ligand pathway. Interestingly, the pretreatment with Vc, a positive stimulator of 5hmC generation, restored 5hmC in the genomic DNA to near-normal levels. More notably, Vc pretreatment further counter-regulated TCBQ-induced alteration of 5hmC abundance in the promoter with 100% of genes, accompanying the reverse modulation of mRNA expressions in 89% of genes. These data from Vc pretreatment supported the relationship between TCBQ-induced apoptosis and the altered 5hmC abundance. Additionally, Vc also suppressed TCBQ-stimulated generation of ROS, and further increased the stability of mitochondria. Our study illuminates a new mechanism of TCBQ-induced 5hmC-dependent apoptosis, and the dual mechanisms of Vc against TCBQ-stimulated apoptosis via reversely regulating 5hmC levels and scavenging ROS. The work also provided a possible strategy for the detoxification of TCBQ.

Selenium mitigates the inhibitory effect of TBBPA on NETs release by regulating ROS/MAPK pathways-induced carp neutrophil apoptosis and necroptosis

Tetrabromobisphenol A (TBBPA) is one of the most common and persistent organic pollutants found in the environment. When TBBPA is ingested by organisms through various pathways and stored in the body, it shows obvious harmful effects. Selenium (Se) works as an antioxidant in the body, allowing it to withstand the poisonous effects of dangerous substances. The effects and mechanisms of Se and TBBPA on carp neutrophil immune function, apoptosis, and necroptosis, however, are unknown. As a result, we created TBBPA exposure and Se antagonism models using carp neutrophils as study objects, and we investigated the expression of genes implicated in extracellular traps (NETs), cytokines, apoptosis, and necroptosis. The findings demonstrated that extracellular traps neutrophils in the TBBPA group displayed the inhibition of NETs, apoptosis, and necrosis, as well as an increase in Reactive oxygen species (ROS) levels and activation of the MAPK pathway. The expression of genes related to the mitochondrial apoptosis pathway (Bax, Cyt-c, Bcl-2 and Caspase-3) and necroptosis pathway (MLKL, RIPK1, RIPK3, Caspase-8 and FADD) were activated. The expression of inflammatory factors IL-1 and TNF-α were increased, and the expression of IL-2 and IFN-γ were decreased. But an appropriate concentration of Se can mitigate the effects of TBBPA. Our results suggest that Se can mitigate the inhibitory effect of TBBPA on NETs release by regulating apoptosis and necroptosis of carp neutrophil via ROS/MAPK pathways. These results provide a basis information for exploring the toxicity of TBBPA, and enrich the anti-toxicity mechanism of trace element Se in the body.

ERK/p38/ROS burst responses to environmentally relevant concentrations of diphenyl phosphate-evoked neutrophil extracellular traps formation: Assessing the role of autophagy

Organophosphorus compounds were proposed to impair immune surveillance and increase the total burden of pathogens. However, scarce attention has been paid to the effects of organophosphate flame retardants (OPFRs) on neutrophils. Previous literature outlined that neutrophil extracellular traps (NETs) death (NETosis) is associated with autophagy-related signaling. Here we found that 20 μM diphenyl phosphate (DPHP) could promote NETs formation via assessing markers of NETs and the morphological changes. Concurrently, flow cytometry and western blot analysis revealed that DPHP-triggered NETs formation was associated with reactive oxygen species (ROS) burst and activation of extracellular signal-regulated kinase (ERK) and p38. Additionally, the results revealed that autophagy occurred in DPHP-triggered NETs formation, manifested as enhanced LC3B protein expressions and reduced p62 protein expressions. Mechanism dissection revealed that inhibition of autophagy by 3-methyladenine (3-MA) alleviated the ROS burst and subsequent NETosis caused by DPHP. Conversely, autophagy enhancer Rapamycin (Rapa) augmented the above effects of DPHP, including the generation of ROS and NETosis. Collectively, these data suggested ERK/p38 signaling and ROS burst might be an important cause of DPHP-triggered NETs formation, while suppression of excessive autophagy could rescue these actions. These observations provided a theoretical basis for the treatment and prevention of OPFRs-induced immunotoxicity.

Trypanosoma brucei Lipophosphoglycan Induces the Formation of Neutrophil Extracellular Traps and Reactive Oxygen Species Burst via Toll-Like Receptor 2, Toll-Like Receptor 4, and c-Jun N-Terminal Kinase Activation

Trypanosoma brucei brucei is the causative agent of African animal trypanosomosis, which mainly parasitizes the blood of the host. Lipophosphoglycan (LPG), a polymer anchored to the surface of the parasites, activates the host immune response. In this study, we revealed that T. brucei LPG stimulated neutrophils to form neutrophil extracellular traps (NETs) and release the reactive oxygen species (ROS). We further analyzed the involvement of toll-like receptor 2 (TLR2) and toll-like receptor 4 (TLR4) and explored the activation of signaling pathway enzymes in response to LPG stimulation. During the stimulation of neutrophils by LPG, the blockade using anti-TLR2 and anti-TLR4 antibodies reduced the phosphorylation of c-Jun N-terminal kinase (JNK), the release of DNA from the NETs, and the burst of ROS. Moreover, the addition of JNK inhibitor and nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor exhibited similar effects. Our data suggest that T. brucei LPG activates the phosphorylation of JNK through TLR2 and TLR4 recognition, which causes the formation of NETs and the burst of ROS.