Inorganic arsenic administration suppresses human neutrophil function in vitro

Immunoadjuvant therapy in the regulation of cell death in sepsis: recent advances and future directions

Sepsis is characterized by a concomitant early pro-inflammatory response by immune cells to an infection, and an opposing anti-inflammatory response that results in protracted immunosuppression. The primary pathological event in sepsis is widespread programmed cell death, or cellular self-sacrifice, of innate and adaptive immune cells, leading to profound immunological suppression. This severe immune dysfunction hampers effective primary pathogen clearance, thereby increasing the risk of secondary opportunistic infections, latent viral reactivation, multiple organ dysfunction, and elevated mortality. The types of cell death include apoptosis (type I programmed cell death), autophagy (type II programmed cell death), NETosis (a program for formation of neutrophil extracellular traps (NETs)) and other programmed cell deaths like pyroptosis, ferroptosis, necroptosis, each contributing to immunosuppression in distinct ways during the later phases of sepsis. Extensive apoptosis of lymphocytes, such as CD4+, CD8+ T cells, and B cells, is strongly associated with immunosuppression. Apoptosis of dendritic cells further compromises T and B cell survival and can induce T cell anergy or promote regulatory Treg cell proliferation. Moreover, delayed apoptosis and impaired neutrophil function contribute to nosocomial infections and immune dysfunction in sepsis. Interestingly, aberrant NETosis and the subsequent depletion of mature neutrophils also trigger immunosuppression, and neutrophil pyroptosis can positively regulate NETosis. The interaction between programmed cell death 1 (PD-1) or programmed cell death 1 ligand (PD-L1) plays a key role in T cell modulation and neutrophil apoptosis in sepsis. The dendritic cell growth factor, Fms-like tyrosine kinase (FLTEL), increases DC numbers, enhances CD 28 expression, attenuates PD-L1, and improves survival in sepsis. Recently, immunoadjuvant therapies have attracted attention for their potential to restore host physiological immunity and homeostasis in patients with sepsis. This review focuses on several potential immunotherapeutic agents designed to bolster suppressed innate and adaptive immune responses in the management of sepsis.

Innovative Bio-based Hydrogel Microspheres Micro-Cage for Neutrophil Extracellular Traps Scavenging in Diabetic Wound Healing

Neutrophil extracellular traps (NETs) seriously impede diabetic wound healing. The disruption or scavenging of NETs using deoxyribonuclease (DNase) or cationic nanoparticles has been limited by liberating trapped bacteria, short half-life, or potential cytotoxicity. In this study, a positive correlation between the NETs level in diabetic wound exudation and the severity of wound inflammation in diabetic patients is established. Novel NETs scavenging bio-based hydrogel microspheres 'micro-cage', termed mPDA-PEI@GelMA, is engineered by integrating methylacrylyl gelatin (GelMA) hydrogel microspheres with cationic polyethyleneimine (PEI)-functionalized mesoporous polydopamine (mPDA). This unique 'micro-cage' construct is designed to non-contact scavenge of NETs between nanoparticles and the diabetic wound surface, minimizing biological toxicity and ensuring high biosafety. NETs are introduced into 'micro-cage' along with wound exudation, and cationic mPDA-PEI immobilizes them inside the 'micro-cage' through a strong binding affinity to the cfDNA web structure. The findings demonstrate that mPDA-PEI@GelMA effectively mitigates pro-inflammatory responses associated with diabetic wounds by scavenging NETs both in vivo and in vitro. This work introduces a novel nanoparticle non-contact NETs scavenging strategy to enhance diabetic wound healing processes, with potential benefits in clinical applications.

CircP50 functions through the phosphorylation- and acetylation-activated p53 pathway to mediate inorganic arsenic-induced apoptosis in A549 cells

As a class I carcinogen, arsenic has been reported to cause diseases accompanied by circRNAs regulating proliferation and apoptosis at the molecular level, but whether circP50 (circBase ID: hsa_circ_0008012) does the same has not been demonstrated. The aim of this study is to provide the basis for anti-lung cancer mechanism research, by studying the expression of circP50 under arsenic-induced conditions, and the effect and mechanism on the proliferation and apoptosis of A549 cells based on the circP50 knockdown models. To explore whether the circP50 is responsive to arsenic exposure, the qRT-PCR was applied to discover that the relative expression of circP50 in A549 cells increased only with increasing NaAsO₂ dose and independent of its metabolites. We further determined the mechanism of circP50 by establishing circP50 knockdown models. The results of cell viability and EdU assays indicated the proliferation of A549 cells. According to the western blotting, phosphorylation of p53 at Ser15, Ser376, and Ser392 and acetylation of p53 at Lys370 and Lys382 were inhibited, resulting in the deficiency of p53 expression. Subsequently, the expression of genes downstream of p53 was reduced, including p21, PUMA, Caspase3, and Bcl-xS. Furthermore, the expressions of IKB-α, p65, and p50 decreased, but C-myc expression did not change significantly, referring to the NF-κB pathway was not dominant. The results suggest that circP50 mainly functions through the p53 pathway to mediate apoptosis in response to arsenic exposure.

Arsenic as an immunotoxicant

Arsenic is world-wide contaminant to which millions of people are exposed. The health consequences of arsenic exposure are varied, including cancer, cardiometabolic disease, and respiratory disorders. Arsenic is also toxic to the immune system, which may link many of the pathologies associated with arsenic exposure. The immune system can be classified into two interconnected arms: the innate and the adaptive immune responses. Herein, we discuss the effects of arsenic on key cell types within each of these arms, highlighting both in vitro and in vivo responses. These cells include macrophages, neutrophils, dendritic cells, and both B and T lymphocytes. Furthermore, we will explore data from human populations where altered immune status is implicated in disease and identify several data gaps where research is needed to complete our understanding of the immunotoxic effects of arsenic.