Mast Cell Proteases Activate Astrocytes and Glia-Neurons and Release Interleukin-33 by Activating p38 and ERK1/2 MAPKs and NF-κB

Abstract

Inflammatory mediators released from activated microglia, astrocytes, neurons, and mast cells mediate neuroinflammation. Parkinson's disease (PD) is characterized by inflammation-dependent dopaminergic neurodegeneration in substantia nigra. 1-Methyl-4-phenylpyridinium (MPP), a metabolite of parkinsonian neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), induces inflammatory mediators' release from brain cells and mast cells. Brain cells' interaction with mast cells is implicated in neuroinflammation. However, the exact mechanisms involved are not yet clearly understood. Mouse fetal brain-derived cultured primary astrocytes and glia-neurons were incubated with mouse mast cell protease-6 (MMCP-6) and MMCP-7, and mouse bone marrow-derived mast cells (BMMCs) were incubated with MPP and brain protein glia maturation factor (GMF). Interleukin-33 (IL-33) released from these cells was quantitated by enzyme-linked immunosorbent assay. Both MMCP-6 and MMCP-7 induced IL-33 release from astrocytes and glia-neurons. MPP and GMF were used as a positive control-induced IL-33 and reactive oxygen species expression in mast cells. Mast cell proteases and MPP activate p38 and extracellular signal-regulated kinases 1/2 (ERK1/2), mitogen-activated protein kinases (MAPKs), and transcription factor nuclear factor-kappa B (NF-κB) in astrocytes, glia-neurons, or mast cells. Addition of BMMCs from wt mice and transduction with adeno-GMF show higher chemokine (C-C motif) ligand 2 (CCL2) release. MPP activated glial cells and reduced microtubule-associated protein 2 (MAP-2) expression indicating neurodegeneration. IL-33 expression increased in the midbrain and striatum of PD brains as compared with age- and sex-matched control subjects. Glial cells and neurons interact with mast cells and accelerate neuroinflammation and these interactions can be explored as a new therapeutic target to treat PD.

Mast Cell Activation, Neuroinflammation, and Tight Junction Protein Derangement in Acute Traumatic Brain Injury

“…Then, the serum was separated from the clot by centrifugation of tubes at 2000 g for 10 min in a refrigerated centrifuge and stored at -80°C until CCL2 assay by ELISA. Brain tissue sections (20 μ m) were prepared from these brains for the detection of mast cells by toluidine blue and the analysis of PAR-2, NeuN, VEGFR2, claudin 5, and ZO-1 expression by immunofluorescence staining, as we have reported previously [ 21 , 29 ]. Maintenance of mice and the experiments were carried out “according to the recommendations in the G uide for the Care and Use of Laboratory Animals of the National Institutes of Health (NIH) and the approval of the committee on the Ethics of Animal Experiments of the University of Missouri (Columbia, MO).”…”

“…CCL2 level was quantified in the brain lysate and serum using a commercial DuoSet ELISA kit as per the manufacturers' guidelines. The optical density of the plate was read at 450 nm with a microplate reader (Molecular Devices, Sunnyvale, CA), as we have reported previously [ 29 – 31 ].…”

“…Cryostat sections from 24 h and 72 h TBI brains and sham control mouse brains were fixed with a 4% paraformaldehyde solution. Immunofluorescence labeling was performed using an anti-PAR-2 mouse monoclonal antibody (1 : 100) along with an anti-NeuN rabbit polyclonal antibody (1 : 500), as we reported [ 21 , 29 ]. Briefly, the brain sections were incubated with mixed antibodies at 4°C overnight with gentle shaking and incubated with a mixture of Alexa Flour 488 goat anti-rabbit IgG (1 : 300) and anti-mouse IgG/goat anti-mouse Texas red secondary antibodies (1 : 500) for one hour at room temperature with gentle shaking for immunofluorescence labeling.…”

“…Then, the sections were washed with DPBS, mounted, dried, and viewed with a confocal fluorescent microscope (Leica Microsystems GmbH, Germany; at Harry S. Truman Memorial Veterans Hospital, Columbia, MO). Photomicrographs were taken using an oil immersion objective (40x or 63x), as we already reported [ 29 , 32 – 36 ]. Similarly, we have performed double immunofluorescence staining for VEGFR2 (1 : 200), claudin 5 (1 : 100), and ZO-1 (5 μ g/ml) in the brain sections from 24 h and 72 h TBI brains as well as sham control mouse brains along with DAPI for cellular nuclei.…”

Mast cell‑mediated neuroinflammation may have a role in attention deficit hyperactivity disorder (Review)

“…Furthermore, IL-33 may be stimulated from microglia pre-activated with pathogen-associated molecular patterns via TLRs (73,74). Together, MC protease and matrix metalloproteinase (MMP) activate p38, ERK1/2, MAPKs and transcription factors including NF-κB in astrocytes, microglia and MCs (75). IL-6 and TNF-α released from microglia upregulate protease-activated receptor 2 (PAR2) expression in MCs, causing MC activation and TNF-α release (76).…”