Neuroinflammatory response is primarily a protective mechanism in the brain. However, excessive and chronic inflammatory responses can lead to deleterious effects involving immune cells, brain cells and signaling molecules. Neuroinflammation induces and accelerates pathogenesis of Parkinson’s disease (PD), Alzheimer’s disease (AD) and Multiple sclerosis (MS). Neuroinflammatory pathways are indicated as novel therapeutic targets for these diseases. Mast cells are immune cells of hematopoietic origin that regulate inflammation and upon activation release many proinflammatory mediators in systemic and central nervous system (CNS) inflammatory conditions. In addition, inflammatory mediators released from activated glial cells induce neurodegeneration in the brain. Systemic inflammation-derived proinflammatory cytokines/chemokines and other factors cause a breach in the blood brain-barrier (BBB) thereby allowing for the entry of immune/inflammatory cells including mast cell progenitors, mast cells and proinflammatory cytokines and chemokines into the brain. These peripheral-derived factors and intrinsically generated cytokines/chemokines, α-synuclein, corticotropin-releasing hormone (CRH), substance P (SP), beta amyloid 1–42 (Aβ1–42) peptide and amyloid precursor proteins can activate glial cells, T-cells and mast cells in the brain can induce additional release of inflammatory and neurotoxic molecules contributing to chronic neuroinflammation and neuronal death. The glia maturation factor (GMF), a proinflammatory protein discovered in our laboratory released from glia, activates mast cells to release inflammatory cytokines and chemokines. Chronic increase in the proinflammatory mediators induces neurotoxic Aβ and plaque formation in AD brains and neurodegeneration in PD brains. Glial cells, mast cells and T-cells can reactivate each other in neuroinflammatory conditions in the brain and augment neuroinflammation. Further, inflammatory mediators from the brain can also enter into the peripheral system through defective BBB, recruit immune cells into the brain, and exacerbate neuroinflammation. We suggest that mast cell-associated inflammatory mediators from systemic inflammation and brain could augment neuroinflammation and neurodegeneration in the brain. This review article addresses the role of some atypical inflammatory mediators that are associated with mast cell inflammation and their activation of glial cells to induce neurodegeneration.

BackgroundWe evaluated candidate circulating serum cytokines, chemokines and growth factors in patients with locally/regionally advanced melanoma receiving neoadjuvant ipilimumab with toxicity and clinical outcome.MethodsPatients were treated with ipilimumab (10 mg/kg IV every 3 weeks, 2 doses) before and after surgery. xMAP multiplex serum testing for 36 functionally selected cytokines and chemokines was performed at baseline and at six weeks (following ipilimumab). Based on our prior data, the association of IL-17 and immune related colitis was tested. Serum cytokines were divided into functional groups (Th1, Th2, Regulatory, Proinflammatory) and were assessed at baseline and week 6 using sparse-group Lasso modeling to assess the association of various cytokine groups with progression free survival (PFS). The linear combination of the cytokines/chemokines in this model was then used as a risk score and a Kaplan-Meier curve was generated to examine the association of the dichotomized score and PFS.ResultsThirty-five patients were enrolled whose staging was: IIIB (3; N2b), IIIC (30; N2c, N3), IV (2). Median follow-up was 18 months. Among 33 evaluable patients, median PFS was 11 months (95 % CI = 6.2–19.2). IL-17 was found to correlate significantly with the incidence of grade 3 diarrhea/colitis when measured at baseline (p = 0.02) with a trend towards significance at 6 weeks (p = 0.06). In the modeling analysis, at baseline, the linear combination of 2 regulatory cytokines [TGF- β1 (ρ = 0.19) and IL-10 (ρ = -0.34)] was significantly associated with PFS (HR 2.66; p = 0.035). No significant correlations with clinical outcomes were found in examining the week 6 cytokines.ConclusionsBaseline IL-17 level was significantly associated with the later development of severe diarrhea/colitis while the combination of baseline TGF- β1 and IL-10 levels were associated with therapeutic clinical outcome after neoadjuvant ipilimumab. These findings warrant further investigation and validation.Trial registrationClinicalTrials.gov Identifier NCT00972933.

Traumatic brain injury (TBI) is a major health problem in the United States, which affects about 1.7 million people each year. Glial cells, T-cells, and mast cells perform specific protective functions in different regions of the brain for the recovery of cognitive and motor functions after central nervous system (CNS) injuries including TBI. Chronic neuroinflammatory responses resulting in neuronal death and the accompanying stress following brain injury predisposes or accelerates the onset and progression of Alzheimer’s disease (AD) in high-risk individuals. About 5.7 million Americans are currently living with AD. Immediately following brain injury, mast cells respond by releasing prestored and preactivated mediators and recruit immune cells to the CNS. Blood-brain barrier (BBB), tight junction and adherens junction proteins, neurovascular and gliovascular microstructural rearrangements, and dysfunction associated with increased trafficking of inflammatory mediators and inflammatory cells from the periphery across the BBB leads to increase in the chronic neuroinflammatory reactions following brain injury. In this review, we advance the hypothesis that neuroinflammatory responses resulting from mast cell activation along with the accompanying risk factors such as age, gender, food habits, emotional status, stress, allergic tendency, chronic inflammatory diseases, and certain drugs can accelerate brain injury-associated neuroinflammation, neurodegeneration, and AD pathogenesis.

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.

BackgroundNivolumab is approved for the treatment of refractory metastatic renal cell carcinoma. Patterns and predictors of progressive disease (PD) on nivolumab, and outcomes in such patients are lacking.MethodsA retrospective analysis of patients (pts) with metastatic clear cell renal cell carcinoma (ccRCC) who received nivolumab at Cleveland Clinic (2015–2017) was performed. PD was defined per Response Evaluation Criteria in Solid Tumors (RECIST) v1.1 or clinical progression as per treating physician. Univariate analyses (UVA) and multivariate analyses (MVA) were used to identify clinical and laboratory markers as potential predictors of progression-free survival (PFS).ResultsNinety patients with mean age of 65, 74% men, and 83% good or intermediate International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) risk group were included. Median number of prior systemic treatments was 2 (range, 1–6). Median overall survival (OS) and PFS were 15.8 and 4.4 months, respectively. Fifty-seven patients (63%) had PD and 44% of patients with radiographic PD had new organ sites of metastases with brain (8/23, 35%) being the most common. Twelve patients received treatment beyond progression (TBP), and among 6 patients with available data, 3 (50%) had any tumor shrinkage (2 pts. with 17% shrinkage, one pt. with 29% shrinkage). Of 57 patients with PD, 28 patients (49%) were able to initiate subsequent treatment, mainly with axitinib and cabozantinib, while 40% of patients were transitioned to hospice after PD. In MVA, a higher baseline Neutrophil-to-Lymphocyte ratio (NLR) (HR, 1.86; 95% CI, 1.05–3.29; p = 0.033) was associated with an increased risk of progression, whereas higher (> 0.1 k/uL) baseline eosinophil count was associated with a lower risk of progression (HR, 0.54; 95% CI, 0.30–0.98; p = 0.042).ConclusionBrain was the most common site of PD in patients treated with nivolumab, and only half of patients progressing on nivolumab were able to initiate subsequent treatment. The risk of PD increased with a higher baseline NLR and reduced with a higher baseline eosinophil count.Electronic supplementary materialThe online version of this article (10.1186/s40425-018-0425-8) contains supplementary material, which is available to authorized users.