Inhibition of Netosis with PAD Inhibitor Attenuates Endotoxin Shock Induced Systemic Inflammation

A β-Carboline Derivate PAD4 Inhibitor Reshapes Neutrophil Phenotype and Improves the Tumor Immune Microenvironment against Triple-Negative Breast Cancer

Triple-negative breast cancer is a highly aggressive and heterogeneous breast cancer subtype characterized by early metastasis, poor prognosis, and high recurrence. Targeting histone citrullination-mediated chromatin dysregulation to induce epigenetic alterations shows great promise in TNBC therapy. We report the synthesis, optimization, and evaluation of a novel series of β-carboline-derived peptidyl arginine deiminase 4 inhibitors that exhibited potent inhibition of TNBC cell proliferation. The most outstanding PAD4 inhibitor, compound 28, hindered the PAD4-H3cit-NET signaling pathway and inhibited the growth of solid tumors and pulmonary metastatic nodules in the 4T1 in situ mouse model. Furthermore, 28 improved the tumor immune microenvironment by reshaping neutrophil phenotype, upregulating the proportions of dendritic cells and M1 macrophages, and reducing the amount of myeloid-derived suppressor cells. In conclusion, our work offered 28 as an efficacious PAD4 inhibitor that exerts a combination of conventional chemotherapy and immune-boosting effects, which represents a potential therapy strategy for TNBC.

Development of a rectally administrable Dnase1 to treat septic shock by targeting NETs

AIMS

Neutrophil extracellular trap (NET), which is formed by DNA threads, induces septic shock by aggravating systemic inflammation. An intravenous administration of deoxyribonuclease is regarded as a compelling modality for treating septic shock. However, alternative routes should be chosen when cutaneous veins are all collapsed due to hypotension. In this study, we genetically engineered this enzyme to develop a rectal suppository formulation to treat septic shock.

MAIN METHODS

Dnase1 was mutated at two amino acid residues to increase its stability in the blood and fused with a cell-penetrating peptide CR8 to increase its absorption through the rectal mucosa, which is designated AR-CR8. The life-saving effect of AR-CR8 was evaluated in a LPS-induced shock mouse model.

KEY FINDINGS

AR-CR8 was shown to remove NETs effectively in human neutrophils. When AR-CR8 was administered to the mouse rectum, the deoxyribonuclease activity in the mouse serum was significantly increased. In the LPS-induced shock model, 90 % of the control mice died over 72 h after LPS injection. In contrast, the rectal administration of AR-CR8 showed a mortality rate of 30 % by 72 h after LPS injection. The Log-rank test revealed that the survival rate is significantly higher in the AR-CR8 group. The NET markers in the mouse serum were enhanced by LPS, and significantly downregulated in the AR-CR8 group. These results suggest that AR-CR8 ameliorates LPS-induced shock by degrading NETs.

SIGNIFICANCE

The engineered DNASE1 could be developed as a rectal suppository formulation to treat septic shock urgently at out-of-hospital places where no syringe is available.

Contribution of monocyte and macrophage extracellular traps to neutrophilic airway inflammation in severe asthma

BACKGROUND

Increased blood/sputum neutrophil counts are related to poor clinical outcomes of severe asthma (SA), where we hypothesized that classical monocytes (CMs)/CM-derived macrophages (Mφ) are involved. We aimed to elucidate the mechanisms of how CMs/Mφ induce the activation of neutrophils/innate lymphoid cells (ILCs) in SA.

METHODS

Serum levels of monocyte chemoattractant protein-1 (MCP-1) and soluble suppression of tumorigenicity 2 (sST2) were measured from 39 patients with SA and 98 those with nonsevere asthma (NSA). CMs/Mφ were isolated from patients with SA (n = 19) and those with NSA (n = 18) and treated with LPS/interferon-gamma. Monocyte/M1Mφ extracellular traps (MoETs/M1ETs) were evaluated by western blotting, immunofluorescence, and PicoGreen assay. The effects of MoETs/M1ETs on neutrophils, airway epithelial cells (AECs), ILC1, and ILC3 were assessed in vitro and in vivo.

RESULTS

The SA group had significantly higher CM counts with increased migration as well as higher levels of serum MCP-1/sST2 than the NSA group. Moreover, the SA group had significantly greater production of MoETs/M1ETs (from CMs/M1Mφ) than the NSA group. The levels of MoETs/M1ETs were positively correlated with blood neutrophils and serum levels of MCP-1/sST2, but negatively correlated with FEV1%. In vitro/in vivo studies demonstrated that MoETs/M1ETs could activate AECs, neutrophils, ILC1, and ILC3 by increased migration as well as proinflammatory cytokine production.

CONCLUSIONS

CM/Mφ-derived MoETs/M1ETs could contribute to asthma severity by enhancing neutrophilic airway inflammation in SA, where modulating CMs/Mφ may be a potential therapeutic option.

Neutrophil extracellular traps in influenza infection

Despite recent progress in developing novel therapeutic approaches and vaccines, influenza is still considered a global health threat, with about half a million mortality worldwide. This disease is caused by Influenza viruses, which are known for their rapid evolution due to different genetical mechanisms that help them develop new strains with the ability to evade therapies and immunization. Neutrophils are one of the first immune effectors that act against pathogens. They use multiple mechanisms, including phagocytosis, releasing the reactive oxygen species, degranulation, and the production of neutrophil extracellular traps. Neutrophil extracellular traps are used to ensnare pathogens; however, their dysregulation is attributed to inflammatory and infectious diseases. Here, we discuss the effects of these extracellular traps in the clinical course of influenza infection and their ability to be a potential target in treating influenza infection.

Citrullination and the protein code: crosstalk between post-translational modifications in cancer

Post-translational modifications (PTMs) of proteins are central to epigenetic regulation and cellular signalling, playing an important role in the pathogenesis and progression of numerous diseases. Growing evidence indicates that protein arginine citrullination, catalysed by peptidylarginine deiminases (PADs), is involved in many aspects of molecular and cell biology and is emerging as a potential druggable target in multiple diseases including cancer. However, we are only just beginning to understand the molecular activities of PADs, and their underlying mechanistic details in vivo under both physiological and pathological conditions. Many questions still remain regarding the dynamic cellular functions of citrullination and its interplay with other types of PTMs. This review, therefore, discusses the known functions of PADs with a focus on cancer biology, highlighting the cross-talk between citrullination and other types of PTMs, and how this interplay regulates downstream biological events. This article is part of the Theo Murphy meeting issue 'The virtues and vices of protein citrullination'.

Role of Peptidylarginine Deiminase 4 in Central Nervous System Diseases

The deimination or citrullination of arginine residues in the polypeptide chain by peptidylarginine deiminase 4 alters the charge state of the polypeptide chain and affects the function of proteins. It is one of the main ways of protein post-translational modifications to regulate its function. Peptidylarginine deiminase 4 is widely expressed in multiple tissues and organs of the body, especially the central nervous system, and regulates the normal development of organisms. The abnormal expression and activation of peptidylarginine deiminase 4 is an important pathological mechanism for the occurrence and development of central nervous system diseases such as multiple sclerosis, Alzheimer's disease, cerebral ischemia reperfusion injury, and glioblastoma.

Lipid Metabolism Reprogramming of Immune Cells in Acne: An Update

Acne vulgaris is one of the most widespread skin conditions and the main reason for visiting a dermatologist. Inflammatory response and abnormal infiltrations of immune cells are the main pathogenesis of acne. The increased lipid is the prerequisite for the acne, and the perturbation of lipid composition and content is consistent with the severity of acne. Furthermore, the increased lipid production not only contributes to the occurrence and development of acne, but also sensitizes the function of immune cells. The lipid metabolic dysfunction aggravates the severity of local tissue and provides pro-inflammatory-cytokine cues, which indicates the crucial roles of lipid metabolism on immune cells. Recent advances have demonstrated the lipid metabolism reprogramming of various immune cells in acne lesion. The abnormal lipid accumulation, lipolysis, and fatty acid oxidation lead to the activation and differentiation of immune cells, which promotes the pro-inflammatory cytokines production. Thus, this review discusses the emerging role of lipid metabolism reprogramming of immune cells in the progress of acne and aims to constitute food for others' projects involved in acne research.