Mast cell activation and autism.

Autism spectrum disorders (ASD) are neurodevelopmental disorders characterized by varying degrees of dysfunctional communication and social interactions, repetitive and stereotypic behaviors, as well as learning and sensory deficits. Despite the impressive rise in the prevalence of autism during the last two decades, there are few if any clues for its pathogenesis, early detection or treatment. Increasing evidence indicates high brain expression of pro-inflammatory cytokines and the presence of circulating antibodies against brain proteins. A number of papers, mostly based on parental reporting on their children's health problems, suggest that ASD children may present with "allergic-like" problems in the absence of elevated serum IgE and chronic urticaria. These findings suggest non-allergic mast cell activation, probably in response to environmental and stress triggers that could contribute to inflammation. In utero inflammation can lead to preterm labor and has itself been strongly associated with adverse neurodevelopmental outcomes. Premature babies have about four times higher risk of developing ASD and are also more vulnerable to infections, while delayed development of their gut-blood-brain barriers makes exposure to potential neurotoxins likely. Perinatal mast cell activation by infectious, stress-related, environmental or allergic triggers can lead to release of pro-inflammatory and neurotoxic molecules, thus contributing to brain inflammation and ASD pathogenesis, at least in a subgroup of ASD patients. This article is part of a Special Issue entitled: Mast cells in inflammation.

Mast cells and inflammation.

Mast cells are well known for their role in allergic and anaphylactic reactions, as well as their involvement in acquired and innate immunity. Increasing evidence now implicates mast cells in inflammatory diseases where they are activated by non-allergic triggers, such as neuropeptides and cytokines, often exerting synergistic effects as in the case of IL-33 and neurotensin. Mast cells can also release pro-inflammatory mediators selectively without degranulation. In particular, IL-1 induces selective release of IL-6, while corticotropin-releasing hormone secreted under stress induces the release of vascular endothelial growth factor. Many inflammatory diseases involve mast cells in cross-talk with T cells, such as atopic dermatitis, psoriasis and multiple sclerosis, which all worsen by stress. How mast cell differential responses are regulated is still unresolved. Preliminary evidence suggests that mitochondrial function and dynamics control mast cell degranulation, but not selective release. Recent findings also indicate that mast cells have immunomodulatory properties. Understanding selective release of mediators could explain how mast cells participate in numerous diverse biologic processes, and how they exert both immunostimulatory and immunosuppressive actions. Unraveling selective mast cell secretion could also help develop unique mast cell inhibitors with novel therapeutic applications. This article is part of a Special Issue entitled: Mast cells in inflammation.

Rupatadine inhibits inflammatory mediator release from human laboratory of allergic diseases 2 cultured mast cells stimulated by platelet-activating factor.

BACKGROUND: Mast cells are involved in allergy and inflammation by the secretion of multiple mediators, including histamine, cytokines, and platelet-activating factor (PAF), in response to different triggers, including emotional stress. PAF has been associated with allergic inflammation, but there are no clinically available PAF inhibitors. OBJECTIVE: To investigate whether PAF could stimulate human mast cell mediator release and whether rupatadine (RUP), a dual histamine-1 and PAF receptor antagonist, could inhibit the effect of PAF on human mast cells. METHODS: Laboratory of allergic diseases 2 cultured mast cells were stimulated with PAF (0.001, 0.01, and 0.1 µmol/L) and substance P (1 µmol/L) with or without pretreatment with RUP (2.5 and 25 µmol/L), which was added 10 minutes before stimulation. Release of ß-hexosaminidase was measured in supernatant fluid by spectrophotoscopy, and histamine, interleukin-8, and tumor necrosis factor were measured by enzyme-linked immunosorbent assay. RESULTS: PAF stimulated a statistically significant release of histamine, interleukin-8, and tumor necrosis factor (0.001-0.1 µmol/L) that was comparable to that stimulated by substance P. Pretreatment with RUP (25 µmol/L) for 10 minutes inhibited this effect. In contrast, pretreatment of laboratory of allergic diseases 2 cells with diphenhydramine (25 µmol/L) did not inhibit mediator release, suggesting that the effect of RUP was not due to its antihistaminic effect. CONCLUSION: PAF stimulates human mast cell release of proinflammatory mediators that is inhibited by RUP. This action endows RUP with additional properties in treating allergic inflammation.

Turkish version of the chronic urticaria quality of life questionnaire: cultural adaptation, assessment of reliability and validity.

Chronic spontaneous urticaria has a substantial impact on patients' quality of life. The first disease-specific tool to assess quality of life impairment in this condition, the Chronic Urticaria Quality of Life Questionnaire (CU-Q2oL), was developed recently. The aim of this study was to adapt the original Italian version to the Turkish language and to evaluate its reliability, validity, and sensitivity to change. The Turkish version was developed by performing forward- and back-translation. It was then applied to 140 consecutive patients with chronic spontaneous urticaria, along with the Dermatology Life Quality Index and the Skindex-29. Disease activity was assessed using the Urticaria Activity Score. Sensitivity to change was measured in 101 patients, who completed the instruments twice at intervals of 4 weeks. Confirmatory factor analysis demonstrated that the six-scale structure of the original Italian version ("pruritus", "swelling", "impact on life activities", "sleep problems", "limits", "looks") can be retained in the Turkish instrument. Analysis regarding convergent validity showed good correlations of the Turkish CU-Q2oL with the other instruments. In addition, it was found to discriminate well between patients with different levels of urticaria activity, and to be sensitive to change. In conclusion, the Turkish version of CU-Q2oL is a reliable, valid, and sensitive instrument, which will help to characterize better the clinical impact of chronic spontaneous urticaria and treatment outcomes in Turkish patients. Its identical scale structure to that of other CU-Q2oL instruments makes it ideal for cross-cultural comparisons and for its application in future national and multinational studies.

Tacrolimus 0.1% vs mometasone furoate topical treatment in allergic contact hand eczema: a prospective randomized clinical study.

Tacrolimus is a macrolide immunosuppressant that has been demonstrated to inhibit T-lymphocyte activation without the side-effects of corticosteroids. The safety profile of tacrolimus makes it a promising therapeutic option for dermatitis. To evaluate and compare the therapeutic ability of tacrolimus 0.1% ointment and mometasone furoate 0.1% ointment in patients with chronic hand eczema and positive patch tests. Thirty adults with chronic hand eczema and positive patch test reaction to relevant contact allergens were treated with tacrolimus 0.1% ointment or mometasone furoate 0.1% ointment in a single-centre, randomized comparative study. The scores of the evaluated clinical parameters (erythema, infiltration, vesiculation, desquamation, presence of cracks and itching) did not differ between Groups A and B at any of the four time points (p>0.05).On the other hand, in both groups, a significant difference was detected in all parameters between baseline and Day 90 recorded values. Tacrolimus is a promising alternative therapy for contact dermatitis patients as it is effective from the first month of treatment, well tolerated and offers similar therapeutic results to topical corticosteroid therapy.

Human mast cell degranulation and preformed TNF secretion require mitochondrial translocation to exocytosis sites: relevance to atopic dermatitis.

BACKGROUND: Mast cells derive from hematopoietic cell precursors and participate in tissue allergic, immune, and inflammatory processes. They secrete many mediators, including preformed TNF, in response to allergic, neuropeptide, and environmental triggers. However, regulation of mast cell degranulation is not well understood. OBJECTIVE: We investigated the role of mitochondrial dynamics in degranulation of human cultured mast cells. METHODS: Human umbilical cord blood-derived mast cells (hCBMCs) and Laboratory of Allergic Diseases 2 (LAD2) mast cells were examined by confocal and differential interference contrast microscopy during activation by IgE/antigen and substance P (SP). Mast cells in control and atopic dermatitis (AD) skin were evaluated by transmission electron microscopy. LAD2 cells were pretreated with mitochondrial division inhibitor, a dynamin-related protein 1 (Drp1) inhibitor, and small interfering RNA for Drp1, which is necessary for mitochondrial fission and translocation. Calcineurin and Drp1 gene expression was analyzed in stimulated LAD2 cells and AD skin biopsies. RESULTS: Stimulation of hCBMCs with IgE/antigen or LAD2 cells with SP leads to rapid (30 minutes) secretion of preformed TNF. Degranulation is accompanied by mitochondrial translocation from a perinuclear location to exocytosis sites. Extracellular calcium depletion prevents these effects, indicating calcium requirement. The calcium-dependent calcineurin and Drp1 are activated 30 minutes after SP stimulation. Reduction of Drp1 activity by mitochondrial division inhibitor and decrease of Drp1 expression using small interfering RNA inhibit mitochondrial translocation, degranulation, and TNF secretion. Mitochondrial translocation is also evident by transmission electron microscopy in skin mast cells from AD biopsies, in which gene expression of calcineurin, Drp1, and SP is higher than in normal skin. CONCLUSION: Human mast cell degranulation requires mitochondrial dynamics, also implicated in AD.

Neurotensin is increased in serum of young children with autistic disorder.

Autism spectrum disorders (ASD) are a group of pervasive neurodevelopmental disorders diagnosed in early childhood. They are associated with a set of "core symptoms" that include disabilities in social interaction skills, verbal and non-verbal communication, as well as repetitive and stereotypic behaviors. There is no definite pathogenetic mechanism or diagnostic tests. Many children with ASD also have "allergic-like" symptoms, but test negative implying mast cell activation by non-allergic triggers. We measured by Milliplex arrays serum levels of 3 neuropeptides that could stimulate mast cells in children with autistic disorder (n = 19; 16 males and 3 females; mean age 3.0 ± 0.4 years) and healthy, unrelated controls (n = 16; 13 males and 3 females; mean age 3 ± 1.2 years). Only neurotensin (NT) was significantly increased from 60.5 ± 6.0 pg/ml in controls to 105.6 ± 12.4 pg/ml in autistic disorder (p = 0.004). There was no statistically significant difference in the serum levels of ß-endorphin or substance P (SP). NT could stimulate immune cells, especially mast cells, and/or have direct effects on brain inflammation and ASD.

Mitochondrial DNA and anti-mitochondrial antibodies in serum of autistic children.

Autism spectrum disorders (ASD) are neurodevelopmental disorders characterized by difficulties in communication, cognitive and learning deficits, as well as stereotypic behaviors. For the majority of cases there are no reliable biomarkers or distinct pathogenesis. However, increasing evidence indicates ASD may be associated with some immune dysregulation, and may have a neuroimmune component. We recently showed that the peptide neurotensin (NT) is increased in autistic children. We now show that NT induces release of extracellular mitochondrial DNA (mtDNA) that could act as "autoimmune" trigger. We further show that serum from young autistic patients contains mtDNA (n = 20; cytochrome B, p = 0.0002 and 7S, p = 0.006), and anti-mitochondrial antibody Type 2 (n = 14; p = 0.001) as compared to normally developing, unrelated controls (n = 12). Extracellular blood mtDNA and other components may characterize an autistic endophenotype and may contribute to its pathogenesis by activating autoimmune responses.

Cytokines and other mediators in alopecia areata.

Alopecia areata, a disease of the hair follicles with multifactorial etiology and a strong component of autoimmune origin, has been extensively studied as far as the role of several cytokines is concerned. So far, IFN-gamma, interleukins, TNF-alpha, are cytokines that are well known to play a major role in the pathogenesis of the disease, while several studies have shown that many more pathways exist. Among them, MIG, IP-10, BAFF, HLA antigens, MIG, as well as stress hormones are implicated in disease onset and activity. Within the scope of this paper, the authors attempt to shed light upon the complexity of alopecia areata underlying mechanisms and indicate pathways that may suggest future treatments.

Acute generalized exanthematous pustulosis (AGEP) triggered by a spider bite.

BACKGROUND: Acute generalized exanthematous pustulosis (AGEP) is a rare and severe cutaneous reaction usually triggered by drugs. Other causative factors such as viral infections are rarely involved. In this study, we report a case of AGEP caused by a spider bite. CASE SUMMARY: A 56-year-old woman was referred to the allergy unit after a spider bite at the left popliteal fossa, while gardening, 5 days earlier. The offending spider was captured and identified by an entomologist as belonging to the Loxosceles rufescens species. No acute reaction was observed; however, after 24 hours, due to the occurrence of typical dermonecrotic skin lesions associated with erythema and edema, Cefuroxime and Clindamycin were administered intramuscularly after medical advice was given. Almost 72 hours after the spider bite, an erythematous and partly edematous eruption appeared locally in the gluteus area bilaterally, which progressively expanded to the trunk, arms and femors. Within 24 hours dozens of small, pinhead sized, non-follicular pustules were present, mainly in the folds. The patient complained of a burning sensation of the skin in addition to pruritus; and simultaneously had a fever of 38-39 degrees C as the eruption expanded. DISCUSSION: A spider bite may represent a possible causative factor of AGEP. A spider's venom contains sphingomyelinase that stimulates the release of IL8 and GM-CSF, which are involved in AGEP pathogenesis. Whether or not the con-current use of antibiotics has an effect in AGEP appearance when combined with a spider's venom, cannot be excluded.

Anaphylaxis to gadobenate dimeglumine (Multihance): a case report.

BACKGROUND: Gadolinium chelates are relatively safe contrast media used in MRI. Immediate severe adverse effects are exceptionally rare and mostly concern mild anaphylactoid reactions. We report a case of anaphylaxis to gadobenate dimeglumine (Gd-BOPTA, Multihance), a gadolinium-based contrast agent. METHODS: A 32-year-old female patient with a personal history of multiple sclerosis, while undergoing an MRI scan, developed bronchospasm and acute urticaria with diffuse giant pruritic plaques in the first minute of Gd-BOPTA infusion. The procedure was cancelled and acute treatment of the reaction took place. The patient reported 2 additional MRI scans with definite use of unknown contrast media in the past 2 years without any adverse effect. Blood samples were obtained 2 and 48 h after the reaction for measurement of serum tryptase concentration (Pharmacia Diagnostics, Uppsala, Sweden). Skin prick tests and intradermal tests were performed using 1:1,000, 1:100 and 1:10 dilution of the offending agent and alternative gadolinium-based agents [gadodiamide (Omniscan) and gadoteric acid (Dotarem)]. A group of 10 nonatopic individuals who underwent the same skin testing comprised the control group. RESULTS: Tryptase concentration was highly elevated 2 h after the reaction (21 microg/l) compared with that at 48 h (3 microg/l). Skin prick tests in our patient were all negative, while intradermal testing with 0.03 ml of 1:100 and 1:10 preparations of Multihance showed a definite positive wheal-and-flare reaction. Skin tests to the alternative agents showed no response. In the control group, all performed tests were negative. CONCLUSION: We report the first case of an allergic reaction to gadobenate dimeglumine. Besides, skin testing seems to be a precious diagnostic tool which, if positive, strongly suggests a mast cell-mediated underlying mechanism.

The critical role of mast cells in allergy and inflammation.

Mast cells are well known for their involvement in allergic and anaphylactic reactions, but recent findings implicate them in a variety of inflammatory diseases affecting different organs, including the heart, joints, lungs, and skin. In these cases, mast cells appear to be activated by triggers other than aggregation of their IgE receptors (FcepsilonRI), such as anaphylatoxins, immunoglobulin-free light chains, superantigens, neuropeptides, and cytokines leading to selective release of mediators without degranulation. These findings could explain inflammatory diseases, such as asthma, atopic dermatitis, coronary inflammation, and inflammatory arthritis, all of which worsen by stress. It is proposed that the pathogenesis of these diseases involve mast cell activation by local release of corticotropin-releasing hormone (CRH) or related peptides. Combination of CRH receptor antagonists and mast cell inhibitors may present novel therapeutic interventions.

Mast cells in allergic and inflammatory diseases.

Mast cells are important in the development of allergic and anaphylactic reactions, but also in acquired and innate immunity. There is also increasing evidence that mast cells participate in inflammatory diseases, where they can be activated by non-allergic triggers, such as neuropeptides and cytokines, often having synergistic effects as in the case of substance P (SP) and IL-33. Secretion of vasoactive mediators, cytokines and proteinases contribute to the development of coronary artery disease (CAD), as well as to diet-induced obesity and the metabolic syndrome. Mast cells may be able to orchestrate such different biological processes through their ability to release pro-inflammatory mediators selectively without the degranulation typical of allergic reactions. Recent evidence suggests that mitochondrial uncoupling protein 2 (UCP2) and mitochondrial translocation regulate mast cell degranulation, but not selective mediator release. Better understanding of these two processes and how mast cells exert both immunostimulatory and immunosuppressive actions could lead to the development of inhibitors of release of specific mediators with novel therapeutic applications.

Substance P (SP) induces expression of functional corticotropin-releasing hormone receptor-1 (CRHR-1) in human mast cells.

Corticotropin-releasing hormone (CRH) is secreted under stress and regulates the hypothalamic-pituitary-adrenal axis. However, CRH is also secreted outside the brain where it exerts proinflammatory effects through activation of mast cells, which are increasingly implicated in immunity and inflammation. Substance P (SP) is also involved in inflammatory diseases. Human LAD2 leukemic mast cells express only CRHR-1 mRNA weakly. Treatment of LAD2 cells with SP (0.5-2 µM) for 6 hours significantly increases corticotropin-releasing hormone receptor-1 (CRHR-1) mRNA and protein expression. Addition of CRH (1 µM) to LAD2 cells, which are "primed" with SP for 48 hours and then washed, induces synthesis and release of IL-8, tumor necrosis factor (TNF), and vascular endothelial growth factor (VEGF) 24 hours later. These effects are blocked by pretreatment with an NK-1 receptor antagonist. Treatment of LAD2 cells with CRH (1 µM) for 6 hours induces gene expression of NK-1 as compared with controls. However, repeated stimulation of mast cells with CRH (1 µM) leads to downregulation of CRHR-1 and upregulation in NK-1 gene expression. These results indicate that SP can stimulate mast cells and also increase expression of functional CRHR-1, whereas CRH induces NK-1 gene expression. These results may explain CRHR-1 and NK-1 expression in lesional skin of psoriatic patients.

Brief report: "allergic symptoms" in children with Autism Spectrum Disorders. More than meets the eye?

Many children with Autism Spectrum Disorders (ASD) have either family and/or personal history of "allergic symptomatology", often in the absence of positive skin or RAST tests. These symptoms may suggest mast cell activation by non-allergic triggers. Moreover, children with mastocytosis or mast cell activation syndrome (MCAS), a spectrum of rare diseases characterized by increased number of activated mast cells in many organs, appear to have ASD at a rate tenfold higher (1/10 children) than that of the general population (1/100 children). Mast cell activation by allergic, infectious, environmental and stress-related triggers, especially perinatally, would release pro-inflammatory and neurotoxic molecules. We speculate these could disrupt the gut-blood-brain barriers, thus contributing to brain inflammation and ASD pathogenesis. Increased mast cell responsiveness may define at least a subgroup of ASD subjects, who could benefit from inhibition of mast cell activation.