Ingrid M. W. van Hoogstraten

Mechanisms in Allergic Contact Dermatitis

During the past few decades, our understanding of why, where, and when allergic contact dermatitis (ACD) might develop has rapidly increased. Critical discoveries include the identification of T cells as mediators of cell-mediated immunity, their thymic origin and recirculation patterns, and the molecular basis of their specificity to just one or few allergens out of the thousands of allergens known. Progress has also resulted from the identification of genes that determine T-cell function, and the development of monoclonal antibodies that recognize their products. Moreover, the bioindustrial production of large amounts of these products, e.g. cytokines, and the breeding of mice with disruptions in distinct genes (knock-out mice) or provided with additional genes of interest (transgenic mice), have allowed in-depth analysis of skin-inflammatory processes, such as those taking place in ACD.

Successful Induction of Allergic Contact Dermatitis to Mercury and Chromium in Mice

Availability of reproducible mouse models for allergic contact dermatitis (ACD) to the metal allergens nickel, mercury and chromium, would be of great value for pathogenetic and preventive studies. We explored epicutaneous sensitization to nickel, mercury and chromium in mice in which oral grooming of the sensitization site was prevented by a plaster cast around the abdomen and lower thorax. This procedure was based on earlier findings that oral ingestion of allergen could prevent contact sensitization. The present results show that BALB/c mice can be readily sensitized to mercury and chromium using this epicutaneous casting method, without the further use of adjuvants. With nickel, however, neither this method, nor conventional methods involving the use of Freunds complete adjuvant (FCA) were effective.

Human leukocyte antigen DQ2.2 and celiac disease.

ABSTRACT Patients with celiac disease (CD) lacking both human leukocyte antigen (HLA)-DQ2.5 in cis (DQA1*05:01, DQB1*02:01) or trans (DQA1*05:05, DQB1*02:02) configuration and HLA-DQ8 (DQA1*03:01, DQB1*03:02) are considered to be rare. Therefore, absence of these genotypes is commonly used to exclude the diagnosis of CD. To investigate whether this approach is justified, the HLA-distribution in 155 children with CD was studied. A total of 139 (89.7%) patients carried HLA-DQ2.5. Of the remaining patients, 7 (4.5%) carried HLA-DQ8. Interestingly, the 9 (5.8%) patients lacking HLA-DQ2.5 and HLA-DQ8 carried HLA-DQA1*02:01 and -DQB1*02:02 (HLA-DQ2.2). Therefore, HLA-DQ2.2 should be included as an important HLA-type related to CD.

Specific Celiac Disease Antibodies in Children on a Gluten-Free Diet

OBJECTIVE: Celiac disease (CD) is characterized by histologic alterations in small bowel biopsies. Circulating specific CD antibodies at the time of diagnosis and their disappearance after a gluten-free diet support the diagnosis of CD. We aimed to determine the behavior of the CD antibodies immunoglobulin A anti-tissue transglutaminase (anti-TG2) and immunoglobulin A endomysium (EMA) in children with CD after starting a gluten-free diet. METHODS: This was a retrospective multicenter study in the Netherlands between 2001 and 2009. Inclusion criteria were all newly diagnosed patients with CD younger than 19 years who had at least 1 anti-TG2 and/or EMA measurement before and after starting a gluten-free diet. Eight different anti-TG2 kits were used with substrates of guinea pig TG2 in 1 (Sigma) and 7 human-recombinant TG2: Varelisa and EliA Celikey Phadia-GmbH; Orgentec Diagnostica-GmbH; Diarect AG; Roboscreen GmbH; Aeskulisa Diagnostics; Binding Site Ltd. EMA was analyzed with indirect immunofluorescence tests. Statistical analyses were performed by using mixed-model repeated measurements and survival analysis. RESULTS: There were 129 children with CD included (mean age: 5.6 years; SD ± 4.2). The mean concentration of anti-TG2 decreased significantly within 3 months after starting a gluten-free diet (P < .0001). The cumulative percentage of children who became negative for EMA after ½, 1, 1½, and 2 years was 31%, 60%, 74%, and 87%, respectively. For anti-TG2, a comparable trend was shown: 35%, 55%, 64%, and 78%, respectively. CONCLUSIONS: Doctors taking care of children with CD should be aware that the mean concentration of anti-TG2 will show a 74% decrease (95% confidence interval: 69%–79%) after 3 months of gluten-free diet, and ∼80% of the children will be sero-negative for EMA and anti-TG2 after 2 years of the diet.

Development of a concomitant nickel and chromium sensitization model in the guinea pig

Although nickel allergy is the most frequent contact hypersensitivity in man, reports on successful nickel sensitization in experimental animals are scarce. Chromium hypersensitivity, on the other hand, is readily induced in guinea pigs. In this study we set out to obtain reproducible nickel sensitization in guinea pigs, in order to establish an animal model for immunospecific tolerance and desensitization studies in which two non-cross-reacting metal allergens, chromium and nickel, could be studied simultaneously. Strong and reproducible sensitization to nickel was achieved by injecting low amounts of Freunds complete adjuvant and nickel sulfate in a split-adjuvant procedure. Strong erythematous reactions were observed as early as 14 days after sensitization and could be elicited both by intradermal and open epicutaneous challenges. Optimal evaluation was with nickel sulfate administered epicutaneously in 40% dimethyl sulfoxide to enhance skin penetration. Hypersensitivity could be transferred with lymphocytes and not with serum. Sensitization procedures for nickel and chromium then could successfully be combined in a double sensitization procedure. With four different guinea pig strains no genetic restriction was observed for the induction of nickel or chromium sensitivity. However, for both metals a clear sex and age dependence was observed: female guinea pigs reached a higher degree of sensitization than males, whereas sensitization in young animals was relatively weak.

Frequency of lower respiratory tract infections in relation to adaptive immunity in children with Down syndrome compared to their healthy siblings

Aim:  Children with Down syndrome (DS) experience respiratory tract infections (RTIs) more frequently than healthy children. We investigated whether this is related to different immunological characteristics associated with DS.

Innate stimulatory capacity of high molecular weight transition metals Au (gold) and Hg (mercury)

Nickel, cobalt and palladium ions can induce an innate immune response by triggering Toll-like receptor (TLR)-4 which is present on dendritic cells (DC). Here we studied mechanisms of action for DC immunotoxicity to gold and mercury. Next to gold (Na3Au (S2O3)2⋅2H2O) and mercury (HgCl2), nickel (NiCl2) was included as a positive control. MoDC activation was assessed by release of the pro-inflammatory mediator IL-8. Also PBMC were studied, and THP-1 cells were used as a substitution for DC for evaluation of cytokines and chemokines, as well as phenotypic, alterations in response to gold and mercury. Our results showed that both Na3Au (S2O3)2⋅2H2O and HgCl2 induce substantial release of IL-8, but not IL-6, CCL2 or IL-10, from MoDc, PBMC, or THP-1 cells. Also gold and, to a lesser extent mercury, caused modest dendritic cell maturation as detected by increased membrane expression of CD40 and CD80. Both metals thus show innate immune response capacities, although to a lower extent than reported earlier for NiCl2, CoCl2 and Na2 [PdCl4]. Importantly, the gold-induced response could be ascribed to TLR3 rather than TLR4 triggering, whereas the nature of the innate mercury response remains to be clarified. In conclusion both gold and mercury can induce innate immune responses, which for gold could be ascribed to TLR3 dependent signalling. These responses are likely to contribute to adaptive immune responses to these metals, as reflected by skin and mucosal allergies.

Antibody titers against food antigens decrease upon a gluten-free diet, but are not useful for the follow-up of (refractory) celiac disease.

Sascha Gross, Roy L.J. van Wanrooij, Greetje J. Tack, Kyra A. Gelderman, Sjoerd F. Bakker, Ingrid M.W. van Hoogstraten, Eskelina A. Neefjes-Borst, Marco W.J. Schreurs, Gerd Bouma, Chris J.J. Mulder, Boudewina M.E. von Blomberg and Hetty J. Bontkes, Medical Immunology Unit, Department of Pathology, Department of Gastroenterology, VU Medical Centre, Amsterdam and Department of Immunology, Erasmus MC, University Medical Center, Rotterdam, The Netherlands

A multiplex assay to rapidly exclude HLA-DQ2.5 and HLA-DQ8 expression in patients at risk for celiac disease

Abstract Background: Celiac disease (CD) is an inflammatory disorder of the small intestine induced by gluten ingestion. CD has a strong genetic association with human leukocyte antigen (HLA)-DQ2.5 and HLA-DQ8. The absence of HLA-DQ2.5 and HLA-DQ8 has a strong negative predictive value for CD. Genetic screening of HLA-DQ2.5 and HLA-DQ8 in patients at risk is of great value. Methods: We designed, developed, and validated a multiplex assay based on multiplex ligation-dependent probe amplification (MLPA) technology, allowing the simultaneous detection of DQA1*05-DQB1*02, encoding HLA-DQ2.5, and DQA1*03-DQB1*03:02, encoding HLA-DQ8. The amplified products were separated and identified using capillary electrophoresis. Results: When compared with a polymerase chain reaction followed by single-strand conformation polymorphism/ heteroduplex analysis, one discrepancy was found. Sequencing analysis showed that the developed MLPA assay result was correct. Furthermore, we demonstrated that the MLPA method is able to distinguish between the heterozygote and homozygote expression of HLA-DQ2.5 or HLA-DQ8. Conclusions: This study shows that it is possible to rapidly and accurately screen for the absence of HLA-DQ2.5 and HLA-DQ8 using MLPA, excluding patients at risk for CD for further serological or histological follow-up. In addition, MLPA might be an accurate tool to screen for other specific HLA types in the context of disease association in a diagnostic laboratory setting.

Immunostimulatory capacity of dental casting alloys on endotoxin responsiveness

Statement of problem. Oral metal exposure has been associated with systemic and local adverse reactions, probably due to elemental release from the alloys. Although supraphysiological concentrations of salts from dentally applied metals can activate innate cells through TLR4 (Ni, Co, Pd) and TLR3 (Au), whether direct exposure to solid alloys can also trigger innate immune reactivity is still unknown. Purpose. The purpose of this in vitro study was to determine whether dental cast alloy specimens can activate innate cells and influence their responsiveness to bacterial endotoxin. Material and methods. Human monocyte‐derived dendritic cells (MoDC) and THP‐1 cells were cultured on top of different alloy specimens (Ni‐Cr, Co‐Cr, Pd‐Cu, Pd‐Ag, Ti‐6Al‐4V, amalgam, gold, and stainless steel) or in alloy‐exposed culture medium with or without endotoxin (lipopolysaccharide [LPS]; Escherichia coli 055:B5). Interleukin‐8 (IL‐8) production was used as the parameter for innate stimulation and evaluated by enzyme‐linked immunosorbent assay after 24 hours of culture. The statistical significance of the effects of various casting alloys on the secretion of IL‐8 was analyzed by using the nonparametric Wilcoxon rank sum test (&agr;=.05). Results. Dental cast alloys induced IL‐8 production in MoDC and THP‐1 cells, with Au and Pd‐Cu providing the strongest stimulation. The alloy‐exposed culture media tested contained sufficient stimulatory metal ions to induce detectable IL‐8 production in THP‐1 cells, except for the Ni‐Cr and stainless steel exposed media. Au and Pd‐Cu alloys were also most effective in potentiating LPS responsiveness as measured by IL‐8 production. Conclusions. Using an in vitro culture system to expose MoDC and THP‐1 cells to different alloy specimens this study showed that contact with the solid alloys, in particular when they contain Pd or Au, can trigger innate immune responses and augment responsiveness to bacterial endotoxin.