Gold activates mast cells via calcium influx through multiple H2O2-sensitive pathways including L-type calcium channels

Recent Advances of Gold Compounds in Anticancer Immunity

In recent years, gold compounds have gained more and more attentions in the design of new metal anticancer drugs. Numerous researches have reported that gold compounds, in addition to their widely studied cytotoxic antitumor effects, also reverse tumor immune escape and directly facilitate the functions of immune cells, leading to enhanced anticancer effects. This review mainly summarizes our current understandings of antitumor effects of gold drugs and their relationships with various aspects of antitumor immunity, including innate immunity, adaptive immunity, immunogenic cell death, and immune checkpoints, as well as their roles in adverse effects. Some recent examples of anticancer gold compounds are highlighted. The property of gold compounds is expected to combine with anticancer immunotherapy, such as immune checkpoint inhibitors, to develop new anticancer therapeutic strategies.

Anaphylaxis and anaphylactoid reactions associated with the insertion of peripherally inserted central catheters: A multiyear comparative retrospective cohort study

OBJECTIVE

Peripherally inserted central catheters (PICCs) are a mainstay of nonpermanent vascular access devices. In this study, we assessed patients displaying anaphylaxis or anaphylactoid reactions to the PowerPICC SOLO and Groshong PICC (Bard Access Systems) using the Sherlock tip locating system (TLS).

METHODS

Patients from 2 tertiary-care hospitals were systematically monitored over 4 years for adverse events following the insertion of a PICC using the Sherlock TLS. Insertion data were also collected using the BioFlo PICC (Angiodynamics)from a third hospital site and from The Ottawa Hospital over 4 years as an additional comparator. Three definitions of anaphylaxis and anaphylactoid reactions were utilized, and the Cohen κ was used to assess interrater agreement. Analysis of reactions among the patient cohorts was performed using the χ2 test with Yates correction or the Fisher exact test as appropriate.

RESULTS

Among 8,257 insertions using the TLS PICCs, 37 potential reactions (0.45%) were recorded. Using specific definitions for anaphylaxis or anaphylactoid reactions, 54.1%-91.9% met criteria. Comparator populations using data from Calgary (n = 491) and Ottawa (n = 7,889) using the BioFlo PICC insertion found no reactions. Anaphylactic or anaphylactoid reactions were significantly associated with the PowerPICC SOLO and Groshong PICC with the TLS compared to the BioFlo PICC (P < .0001) across all definitions. The largest subset of patients experiencing adverse reactions had cystic fibrosis (CF) (n = 4, 10.8%).

CONCLUSION

Our study results demonstrate significant adverse events associated with the PowerPICC SOLO and Groshong PICC using the Sherlock TLS inserted across a range of patient populations. The incidence rate of anaphylaxis or anaphylactoid reactions in the CF population at our center is significantly higher than in non-CF patients (P < .001).

Gold induces a pseudo-allergic reaction via MRGPRX2 both in vitro and in vivo

The traditional mast cell (MC) degranulation pathway is mediated by crossing-linking of high-affinity IgE receptor (FcεRI), whereas a non-traditional, but analogous, pseudo-allergic way was recently reported to occur via Mas-Related G Protein-Coupled Receptor X2 (MRGPRX2). Severe contact hypersensitivity to metallic gold, typically considered non-sensitizing, has been reported. However, whether gold induces IgE-independent allergy remains unclear. Therefore, this study assessed the effects of gold chloride (CA) on MC activation and its relation to MRGPRX2. Our data show that CA acted on MRGPRX2 to increase cellular calcium levels and induced the release of inflammatory mediators in vitro. Compared to Mrgprb2-knockout (KO) mice, CA dose-dependently induced passive cutaneous anaphylaxis (PCA) in wild-type (WT) mice. Furthermore, peritoneal mast cells (MPMCs) were extracted from WT and Mrgprb2-KO mice and stimulated by CA, but only MPMCs from WT mice could be activated. Our results suggest that CA-induced pseudo-allergic responses are MRGPRX2 dependent.

Angiopoietin1 inhibits mast cell activation and protects against anaphylaxis

Since morbidity and mortality rates of anaphylaxis diseases have been increasing year by year, how to prevent and manage these diseases effectively has become an important issue. Mast cells play a central regulatory role in allergic diseases. Angiopoietin1 (Ang-1) exhibits anti-inflammatory properties by inhibiting vascular permeability, leukocyte migration and cytokine production. However, Ang-1's function in mast cell activation and anaphylaxis diseases is unknown. The results of our study suggest that Ang-1 decreased lipopolysaccharide (LPS)-induced pro-inflammatory cytokines production of mast cells by suppressing IκB phosphorylation and NF-κB nuclear translocation. Ang-1 also strongly inhibited compound 48/80 induced and FcεRI-mediated mast cells degranulation by decreasing intracellular calcium levels in vitro. In vivo lentivirus-mediated delivery of Ang-1 in mice exhibited alleviated leakage in IgE-dependent passive cutaneous anaphylaxis (PCA). Furthermore, exogenous Ang-1 intervention treatment prevented mice from compound 48/80-induced mesentery mast cell degranulation, attenuated increases in pro-inflammatory cytokines, relieved lung injury, and improved survival in anaphylaxis shock. The results of our study reveal, for the first time, the important role of Ang-1 in the activation of mast cells, and identify a therapeutic effect of Ang-1 on anaphylaxis diseases.

Redox-control of the alarmin, Interleukin-1α

The pro-inflammatory cytokine Interleukin-1α (IL-1α) has recently emerged as a susceptibility marker for a wide array of inflammatory diseases associated with oxidative stress including Alzheimer's, arthritis, atherosclerosis, diabetes and cancer. In the present study, we establish that expression and nuclear localization of IL-1α are redox-dependent. Shifts in steady-state H₂O₂ concentrations (SS-[H₂O₂]) resulting from enforced expression of manganese superoxide dismutase (SOD2) drive IL-1α mRNA and protein expression. The redox-dependent expression of IL-1α is accompanied by its increased nuclear localization. Both IL-1α expression and its nuclear residency are abrogated by catalase co-expression. Sub-lethal doses of H₂O₂ also cause IL-1α nuclear localization. Mutagenesis revealed IL-1α nuclear localization does not involve oxidation of cysteines within its N terminal domain. Inhibition of the processing enzyme calpain prevents IL-1α nuclear localization even in the presence of H₂O₂. H₂O₂ treatment caused extracellular Ca²⁺ influx suggesting oxidants may influence calpain activity indirectly through extracellular Ca²⁺ mobilization. Functionally, as a result of its nuclear activity, IL-1α overexpression promotes NF-kB activity, but also interacts with the histone acetyl transferase (HAT) p300. Together, these findings demonstrate a mechanism by which oxidants impact inflammation through IL-1α and suggest that antioxidant-based therapies may prove useful in limiting inflammatory disease progression.

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Sod2-dependent increases in steady-state H₂O₂ promote IL-1α expression.

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H₂O₂ causes nuclear localization of IL-1α and extracellular Ca²⁺ influx.

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Inhibition of the Ca²⁺ regulated calpain prevents H₂O₂ dependent IL-1α nuclear localization.

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Nuclear IL-1α interacts with p300 and promotes NF-κB activity.

TRPM2 contributes to antigen-stimulated Ca²⁺ influx in mucosal mast cells

Food allergy (FA) is a common allergic disease without any currently available effective drug therapies. Mucosal mast cells (MMCs) play a particularly important role in FA, and the increase in their cytosolic Ca(2+) concentration ([Ca(2+)]cyt) is considered to be a principal component of the degranulation process. However, the mechanisms governing Ca(2+) influx remain poorly understood in MMCs. Recent reports have highlighted the functions of the transient receptor potential melastatin 2 (TRPM2) channel in immunocytes, including its role in monocyte chemokine production and macrophage phagocytic activity. Although TRPM2 gene expression has been demonstrated in mast cells, the significance of such expression remains virtually unknown. In this study, we found that antigen-stimulated degranulation was significantly reduced in mucosal-type bone marrow-derived mast cells (mBMMCs) prepared from TRPM2-knockout (TRPM2-KO) mice (TRPM2-KO mBMMCs) and was suppressed following the administration of three TRPM2 inhibitors with different chemical structures, including econazole, flufenamic acid (FFA), and 2-aminoethoxydiphenyl borate. Furthermore, the antigen-stimulated increase in [Ca(2+)]cyt was significantly decreased in TRPM2-KO mBMMCs and was also suppressed by the TRPM2 inhibitors econazole and FFA. In addition, thapsigargin-induced increase in [Ca(2+)]cyt was significantly decreased in TRPM2-KO mBMMCs. These results suggest that TRPM2 may participate in antigen-induced extracellular Ca(2+) influx and subsequent degranulation. In addition, TRPM2 inhibitors were shown to improve food allergic reactions in a mouse model. Together, these results suggest that TRPM2 inhibitors suppress MMC degranulation via regulation of the increase in [Ca(2+)]cyt. Thus, TRPM2 may play a key role in degranulation by modulating intracellular Ca(2+) in MMCs.