Pathomechanisms of Atopic Dermatitis : Special Emphasis on Superantigen, Topical Treatment and Interleukin-33 receptor

Atopic dermatitis (AD) is a common pruritic skin disease with prevalence rates up to 20 % in children and 3 % in adults. Skin barrier defects combined with modified immune responses of the innate and adaptive immune system activate complex pathophysiological pathways that are involved in the development of this disease. AD is characterized by acute flare-ups as well as chronic eczematous pruritic skin lesions and dry skin. It is crucial to clarify the mechanisms underlying AD in order to devise mechanism-based therapeutic approaches. However, the immunological mechanisms participating in AD are far from being completely understood. This thesis investigates mechanisms believed to be involved in atopic skin inflammation by utilizing an AD-like experimental animal model as well as human patients. The AD-like mouse model was also used to examine the model's suitability for evaluating topical medications for treating AD. In addition, this thesis investigates some of the mechanisms in the so-called atopic march. Results highlight new molecular mechanisms involved in AD and the atopic march. Microbial superantigen, derived from Staphylococcus aureus exacerbates the allergen-induced skin inflammation mostly by a mixed Th1/Th2 type inflammation in the presence of both CD8+ and CD4+ T cells and elevated IgE concentrations. This kind of severe inflammation, induced by allergen and superantigen in the murine skin, was declined with topical corticosteroid and calcineurin inhibitor. According to these results, this AD model is both reproducible and suitable for testing novel treatment options in AD. Finally, a recently characterized Th2-promoting cytokine, IL-33, and its receptor, ST2, were investigated in murine models of AD and allergic asthma as well as in human AD and in different cell models. The results obtained from ST2-/- mice suggest that the IL-33/ST2 pathway can regulate innate immune responses and CD8+ T cell mediated responses in the skin and in lung tissue. However, ST2 appeared to be dispensable for the development of Th2 response in the sensitized skin, whereas it was the main inducer of Th2 cytokines in asthmatic airways. Together, these results obtained from the murine model of AD and from the skin of patients with AD reveal new molecular mechanisms involved in AD.Atooppinen ihottuma on yleinen ihosairaus erityisesti lapsilla, mutta se voi jatkua myös läpi elämän. Taudin kehittymiseen liittyy ihon pintakerroksen vaurio, joka muuttaa immuunijärjestelmän solujen aktivoitumista ja toimintaa. Atooppinen ihottuma ilmentyy akuuttina tai kroonisena kutisevana ja kuivana tulehdusalueena. Atooppisen ihottuman tautimekanismien selvittäminen on tärkeää, että voidaan kehittää tautimekanismeihin vaikuttavia hoitomuotoja. Tässä väitöskirjassa on tutkittu atooppisen ihottuman tautimekanismeja käyttäen kokeellista mallia ja potilasnäytteitä. Lisäksi tutkittiin soveltuuko kokeellinen malli ihmisillä käytettävien lääkeaineiden testaukseen. Lopuksi tutkittiin mekanismeja, jotka liittyvät ihon kautta tapahtuvaan herkistymiseen ja lopulta allergisen astman kehittymiseen kokeellisessa mallissa. Tulokset osoittavat, että stafylokokkibakteerin erittämä superantigeeni pahentaa ihotulehdusta kokeellisessa mallissa aiheuttaen Th1 ja Th2 tyypin tulehdusvälittäjäaineiden, sytokiinien lisääntyneen tuotannon. Superantigeenille herkistetyllä ihoalueella oli sekä CD4+ että CD8+ T soluja. Allergeenialtistetussa ihossa superantigeeni lisäsi CD8+ T solujen määrää. Lisäksi allergiaan liittyvien IgE luokan vasta-aineiden tuotanto lisääntyi superantigeenille altistetussa ihossa. Superantigeenin ja allergeenin aiheuttama tulehdusreaktio parantui huomattavasti topikaalisella kortikosteroidilla ja kalsineuriinisalpaajalla. Tulokset osoittavat, että mallia voidaan käyttää uusien atooppisen ihottuman hoitoon tarkoitettujen lääkeaineiden testaukseen. Väitöskirjassa tutkittiin myös hiljattain karakterisoidun tulehdusvälittäjäaineen, interleukiini-33:n ja sen reseptorin, ST2:n, ilmentymistä ja merkitystä atooppisessa ihottumassa, atooppisen ihottuman ja allergisen astman tautimalleissa ja solumalleissa. IL-33 tasot nousivat ihossa allergeeni- ja superantigeenialtistuksessa. Lisäksi filagriinin puutos, joka liittyy keskeisesti ihon pintakerroksen toimintaan, aiheutti spontaanisti IL-33 ja ST2 mRNA tuotannon lisääntymisen ihossa. ST2 on liitetty Th2 soluihin ja sen tuotanto lisääntyi antigeenin, superantigeenin ja ihovaurion yhteydessä. ST2 geenin puuttuminen hiirillä ei kuitenkaan vähentänyt Th2 tyypin sytokiinien tuotantoa atooppisen ihottuman mallissa. Lisäksi geenin puuttuminen lisäsi CD8+ T solujen, makrofaagien ja neutrofiilien määrää herkistetyllä iholla. Merkittävää oli Th2 tyypin sytokiinien väheneminen keuhkokudoksessa ihon kautta herkistetyillä hiirillä. Tuloksista saadaan uutta tietoa Th2 tyyppisestä reaktiosta ihossa ja keuhkoissa

Verisolujen integriinit ja taudit

English summaryPeer reviewe

Verisolujen integriinit ja taudit

English summaryPeer reviewe

A Randomized, Open-Label Trial of Hen's Egg Oral Immunotherapy : Efficacy and Humoral Immune Responses in 50 Children

BACKGROUND: Egg allergy is the second most common food allergy in children. Persistent food allergy increases the risk of anaphylaxis and reduces the quality of life. OBJECTIVE: To determine the efficacy of oral immunotherapy (OIT) with raw egg white powder and study its effects on humoral responses in children with persistent egg allergy. METHODS: Fifty children aged 6 to 17 years with egg allergy, diagnosed by double-blind, placebo-controlled food challenge, were randomized 3:2 to 8 months of OIT with a maintenance dose of 1 g of egg white protein or 6 months of avoidance after which the avoidance group crossed over to OIT. We examined changes in IgE, IgG4, and IgA concentrations to Gal d 1-4 during OIT compared with avoidance and assessed clinical reactivity at 8 and 18 months. RESULTS: After 8 months, 22 of 50 children (44%) on OIT and 1 of 21 (4.8%) on egg avoidance were desensitized to the target dose, 23 of 50 (46%) were partially desensitized (dosePeer reviewe

Beta2-Integrins and Interacting Proteins in Leukocyte Trafficking, Immune Suppression, and Immunodeficiency Disease

Beta2-integrins are complex leukocyte-specific adhesion molecules that are essential for leukocyte (e.g., neutrophil, lymphocyte) trafficking, as well as for other immunological processes such as neutrophil phagocytosis and ROS production, and T cell activation. Intriguingly, however, they have also been found to negatively regulate cytokine responses, maturation, and migratory responses in myeloid cells such as macrophages and dendritic cells, revealing new, and unexpected roles of these molecules in immunity. Because of their essential role in leukocyte function, a lack of expression or function of beta2-integrins causes rare immunodeficiency syndromes, Leukocyte adhesion deficiency type I, and type III (LAD-I and LAD-III). LAD-I is caused by reduced or lost expression of beta2-integrins, whilst in LAD-III, beta2-integrins are expressed but dysfunctional because a major integrin cytoplasmic regulator, kindlin-3, is mutated. Interestingly, some LAD-related phenotypes such as periodontitis have recently been shown to be due to an uncontrolled inflammatory response rather than to an uncontrolled infection, as was previously thought. This review will focus on the recent advances concerning the regulation and functions of beta2-integrins in leukocyte trafficking, immune suppression, and immune deficiency disease.Peer reviewe

Integrative Transcriptomics Reveals Activation of Innate Immune Responses and Inhibition of Inflammation During Oral Immunotherapy for Egg Allergy in Children

We previously reported the results of a randomized, open-label trial of egg oral immunotherapy (OIT) in 50 children where 44% were desensitized and 46% were partially desensitized after 8 months of treatment. Here we focus on cell-mediated molecular mechanisms driving desensitization during egg OIT. We sought to determine whether changes in genome-wide gene expression in blood cells during egg OIT correlate with humoral responses and the clinical outcome. The blood cell transcriptome of 50 children receiving egg OIT was profiled using peripheral blood mononuclear cell (PBMC) samples obtained at baseline and after 3 and 8 months of OIT. We identified 467 differentially expressed genes (DEGs) after 3 or 8 months of egg OIT. At 8 months, 86% of the DEGs were downregulated and played a role in the signaling of TREM1, IL-6, and IL-17. In correlation analyses, Gal d 1-4-specific IgG4 antibodies associated positively with DEGs playing a role in pathogen recognition and antigen presentation and negatively with DEGs playing a role in the signaling of IL-10, IL-6, and IL-17. Desensitized and partially desensitized patients had differences in their antibody responses, and although most of the transcriptomic changes were shared, both groups had also specific patterns, which suggest slower changes in partially desensitized and activation of NK cells in the desensitized group. OIT for egg allergy in children inhibits inflammation and activates innate immune responses regardless of the clinical outcome at 8 months. Changes in gene expression patterns first appear as posttranslational protein modifications, followed by more sustained epigenetic gene regulatory functions related to successful desensitization.Peer reviewe

Long-term changes in milk component immunoglobulins reflect milk oral immunotherapy outcomes in Finnish children

Background Milk oral immunotherapy (OIT) may increase the amount of milk protein that can be ingested without triggering an allergic reaction. It is important to understand why some patients benefit from the treatment while others do not. Objective The aim was to define the differences in the milk allergen component-specific (casein, alpha-lactalbumin, ss-lactoglobulin) immunoglobulin (sIg [sIgE, sIgG4, and sIgA]) levels relative to the long-term outcomes of milk OIT. Methods In this long-term, open-label follow-up study, 286 children started milk OIT between 2005 and 2015. Follow-up data were collected at two points: the post-buildup phase and long term (range 1-11 years, median 6 years). Comparisons of sIg levels were made among three outcome groups of self-reported long-term milk consumption (high-milk dose, low-milk dose, and avoidance). Results A total of 168 (59%) of the 286 patients on OIT participated. Most patients (57%) were in the high-dose group; here, 80% of these patients had a baseline casein sIgE value less than 28 kUA/L, they had the lowest casein sIgE levels at all time (p < .001), their casein sIgG4/IgE levels increased, and long-term casein sIgA was highest compared with the low-dose and avoidance groups (p = .02). Low-milk dose group had the highest casein sIgG4/IgE levels in long term (p = .002). Conclusion The baseline Ig profiles and responses to milk OIT differed depending on long-term milk consumption. Lower casein sIgE levels were associated with better outcome. Milk casein sIgA differed in the long term among high-milk consumers.Peer reviewe

A beta2-Integrin/MRTF-A/SRF Pathway Regulates Dendritic Cell Gene Expression, Adhesion, and Traction Force Generation

beta2-integrins are essential for immune system function because they mediate immune cell adhesion and signaling. Consequently, a loss of beta2-integrin expression or function causes the immunodeficiency disorders, Leukocyte Adhesion Deficiency (LAD) type I and III. LAD-III is caused by mutations in an important integrin regulator, kindlin-3, but exactly how kindlin-3 regulates leukocyte adhesion has remained incompletely understood. Here we demonstrate that mutation of the kindlin-3 binding site in the b2-integrin (TTT/AAA-b2-integrin knock-in mouse/KI) abolishes activation of the actin-regulated myocardin related transcription factor A/serum response factor (MRTF-A/SRF) signaling pathway in dendritic cells and MRTF-A/SRF-dependent gene expression. We show that Ras homolog gene family, member A (RhoA) activation and filamentous-actin (F-actin) polymerization is abolished in murine TTT/AAA-b2-integrin KI dendritic cells, which leads to a failure ofMRTF-A to localize to the cell nucleus to coactivate genes together with SRF. In addition, we show that dendritic cell gene expression, adhesion and integrin-mediated traction forces on ligand coated surfaces is dependent on the MRTF-A/SRF signaling pathway. The participation of b2-integrin and kindlin-3-mediated cell adhesion in the regulation of the ubiquitous MRTF-A/SRF signaling pathway in immune cells may help explain the role of b2-integrin and kindlin-3 in integrin-mediated gene regulation and immune system function.Peer reviewe

Anti-Inflammatory Effects of Metformin Irrespective of Diabetes Status

Rationale: The diabetes drug metformin is under investigation in cardiovascular disease but the molecular mechanisms underlying possible benefits are poorly understood. Objective: Here we have studied anti-inflammatory effects of the drug and their relationship to anti-hyperglycaemic properties. Methods and Results: In primary hepatocytes from healthy animals, metformin and the IKKβ inhibitor BI605906 both inhibited TNFα-dependent IκB degradation and expression of pro-inflammatory mediators IL-6, IL-1b, and CXCL1/2. Metformin suppressed IKKα/β activation, an effect which could be separated from some metabolic actions, in that BI605906 did not mimic effects of metformin on lipogenic gene expression, glucose production and AMPK activation. Equally AMPK was not required either for mitochondrial suppression of IκB degradation. Consistent with discrete anti-inflammatory actions, in macrophages metformin specifically blunted secretion of pro-inflammatory cytokines, without inhibiting M1/M2 differentiation or activation. In a large treatment naïve diabetes population cohort, we observed differences in the systemic inflammation marker, Neutrophil to Lymphocyte Ratio (NLR), following incident treatment with either metformin or sulfonylurea monotherapy. Compared to sulfonylurea exposure, metformin reduced the mean log-transformed NLR after 8-16 months by 0.09 units (95% CI=0.02-0.17, p=0.013), and increased the likelihood that NLR would be lower than baseline after 8-16 months (OR 1.83, 95% CI=1.22-2.75, p=0.00364). Following up these findings in a double blind placebo controlled trial in nondiabetic heart failure (trial registration: NCT00473876), metformin suppressed plasma cytokines including the ageing-associated cytokine CCL11. Conclusions: We conclude that anti-inflammatory properties of metformin are exerted irrespective of diabetes status. This may accelerate investigation of drug utility in non-diabetic cardiovascular disease groups

Hiilinanoputkien aiheuttamien terveysvaikutusten karakterisointi systeemitoksikologian avulla

Hiilinanoputket ovat monikäyttöisiä teollisia nanomateriaaleja, jotka soveltuvat lukuisiin teollisuusaloihin. Hiilinanoputkien asbestin kaltainen muoto on kuitenkin nostanut esiin kysymyksiä niiden turvallisuudesta.1