Effect of anaphylactic shock on suppressors of cytokine signaling

HDAC6-MYCN-CXCL3 axis mediates allergic inflammation and is necessary for allergic inflammation-promoted cellular interactions

Histone deacetylase 6 (HDAC6) has been shown to play an important role in allergic inflammation. This study hypothesized that novel downstream targets of HDAC6 would mediate allergic inflammation. Experiments employing HDAC6 knock out C57BL/6 mice showed that HDAC6 mediated passive cutaneous anaphylaxis (PCA) and passive systemic anaphylaxis (PSA). Antigen stimulation increased expression of N-myc (MYCN) and CXCL3 in an HDAC6-dependent manner in the bone marrow-derived mast cells. MYCN and CXCL3 were necessary for both PCA and PSA. The role of early growth response 3 (EGR3) in the regulation of HDAC6 expression has been reported. ChIP assays showed EGR3 as a direct regulator of MYCN. miR-34a-5p was predicted to be a negative regulator of MYCN. Luciferase activity assays showed miR-34a-5p as a direct regulator of MYCN. miR-34a-5p mimic negatively regulated PCA and PSA. MYCN decreased miR-34a-5p expression in antigen-stimulated rat basophilic leukemia cells (RBL2H3). MYCN was shown to bind to the promoter sequence of CXCL3. In an IgE-independent manner, recombinant CXCL3 protein increased expression of HDAC6, MYCN, and β-hexosaminidase activity in RBL2H3 cells. Mouse recombinant CXCL3 protein enhanced the angiogenic potential of the culture medium of RBL2H3. CXCL3 was necessary for the enhanced angiogenic potential of the culture medium of antigen-stimulated RBL2H3. The culture medium of RBL2H3 was able to induce M2 macrophage polarization in a CXCL3-dependent manner. Recombinant CXCL3 protein also increased the expression of markers of M2 macrophage. Thus, the identification of the novel role of HDAC6-MYCN-CXCL3 axis can help better understand the pathogenesis of anaphylaxis.

FcεRI-HDAC3-MCP1 Signaling Axis Promotes Passive Anaphylaxis Mediated by Cellular Interactions

Anaphylaxis is an acute and life-threatening systemic reaction. Food, drug, aero-allergen and insect sting are known to induce anaphylaxis. Mast cells and basophils are known to mediate Immunoglobulin E (IgE)-dependent anaphylaxis, while macrophages, neutrophils and basophils mediate non IgE-dependent anaphylaxis. Histone deacetylases (HDACs) play various roles in biological processes by deacetylating histones and non-histones proteins. HDAC inhibitors can increase the acetylation of target proteins and affect various inflammatory diseases such as cancers and allergic diseases. HDAC3, a class I HDAC, is known to act as epigenetic and transcriptional regulators. It has been shown that HDAC3 can interact with the high-affinity Immunoglobulin E receptor (FcεRI), to mediate passive anaphylaxis and cellular interactions during passive anaphylaxis. Effects of HDAC3 on anaphylaxis, cellular interactions involving mast cells and macrophages during anaphylaxis, and any tumorigenic potential of cancer cells enhanced by mast cells will be discussed in this review. Roles of microRNAs that form negative feedback loops with hallmarks of anaphylaxis such as HDAC3 in anaphylaxis and cellular interactions will also be discussed. The roles of MCP1 regulated by HDAC3 in cellular interactions during anaphylaxis are discussed. Roles of exosomes in cellular interactions mediated by HDAC3 during anaphylaxis are also discussed. Thus, review might provide clues for development of drugs targeting passive anaphylaxis.

Mediators released during human anaphylaxis

A range of mediators are generated during anaphylaxis, with redundancy of effects, multiple overlapping pathways, and involvement of several cell types. Key steps in the reaction occur at the site of initial contact, and mediators may not be detectable systemically. Furthermore, the potencies of various mediators vary enormously, and clinical effects may occur below our level of detection. We also do not know what converts (amplifies) a local reaction into systemic anaphylaxis. Murine models have identified several novel mediators that may propagate and/or regulate this process and also indicate that circulating neutrophils may play an important role in reaction amplification. Differential expression of various genes within specific intracellular signalling pathways of mediator release may further explain the varying severities of anaphylactic reactions. As our knowledge of the mechanisms of activation, key mediators, and the regulation of mediator release improves, new treatments for prevention and acute management may emerge.

Anaphylaxis

PURPOSE OF REVIEW

This article aims to make a review of the up-to-date knowledge on anaphylaxis and outline the recent advances on pathophysiology, diagnosis, and management of anaphylaxis.

RECENT FINDINGS

New data confirm the increase in prevalence of anaphylaxis and emphasize immunopathologic mechanisms. However, anaphylaxis is often underdiagnosed and guidelines are poorly applied, particularly in emergency departments.

SUMMARY

An improvement of rapid diagnosis and treatment combined with education of population will decrease mortality and morbidity of anaphylaxis.