Allergic skin diseases : studies on mechanisms in experimental atopic dermatitis and allergic contact dermatitis

Atopic dermatitis (AD) is an allergic skin disease, characterized by relapsing eczema, dry skin and chronic skin inflammation. A large proportion of AD patients develop other allergies or asthma later in life. Allergic contact dermatitis (ACD) in turn, is one of the leading occupational diseases worldwide. Therefore, allergic skin diseases not only impair the quality of life of patients but also cause a great economical burden for the society. This thesis investigates some of the mechanisms behind allergic skin diseases. In an AD-model, an AD-like skin inflammation was induced by mechanical skin injury and epicutaneous sensitization. This induced a Th2 cytokine dominated inflammatory response at the site of allergen exposure, and elevation of allergy-related IgE antibody levels in the serum. The effects of skin colonizing bacteria Staphylococcus aureus derived enterotoxin B (SEB) were evaluated on the inflammatory response in AD-model. SEB application significantly exacerbated the allergen induced inflammatory response in the skin, increasing cellular infiltration, enhancing Th2 cytokine production and provoking Th1 cytokine production. Furthermore, SEB induced the production of SEB-specific IgE antibodies and enhanced the production of allergen-specific IgE antibodies. These results demonstrate that bacterial skin colonization may both augment the inflammatory response in AD patients and play a role in the chronification of the disease. Although regulatory T cells (Treg) are known to prevent allergic responses, their role in AD is still not clear. We utilized DEREG mice, in which the Foxp3+ Treg cells can be transiently depleted, to study the role of Foxp3+ Treg cells in the AD-like skin inflammation. The epidermal barrier in AD patients is often damaged by scratching or genetic defect. We observed that in the absence of Foxp3+ Treg cells, the skin injury alone induced a stronger inflammation compared with WT. The addition of allergen further enhanced the inflammatory response and especially increased the production of Th2 cytokines, suggesting that Foxp3+ cells are also essential in controlling the allergic responses in the skin. In addition, when allergen was administered into the lungs at a time point when the Treg compartment had been restored, augmented inflammatory response was observed in the lungs, indicating, that impaired Foxp3+ Treg function during skin sensitization may modulate the possible asthma responses developing later on. In the ACD-model, the skin inflammation was induced by epicutaneous application of oxazolone in two phases: sensitization, when memory cells against the hapten were generated and elicitation, when the same hapten was applied on the skin, resulting in a clinically observed inflammatory response. The role of Foxp3+ Treg cells was studied in these two phases and also in the clearance of the inflammation. The absence of Foxp3+ Treg cells in the sensitization phase dramatically exacerbated the skin inflammation, whereas the absence in the elicitation phase had no effect on the inflammatory response during the first 24 hours post challenge. Instead, both depletions severely impaired the resolution of the inflammation, most likely due to the impaired ability of restored Foxp3+ Treg cells to accumulate in the skin. These results reveal that Foxp3+ Treg cells are crucial during the sensitization phase in the LNs and during the resolution phase in the skin. CCR4 is a chemokine receptor which together with chemokine receptor CCR10 is involved in lymphocyte trafficking into the skin. Surprisingly, the ACD response in CCR4 knock-out mice was exacerbated as compared with WT. When the inflammatory response was followed at different time points after sensitization and challenge, increased proliferation of CD4+ cells was observed in CCR4-/- mice, indicating that CCR4 is somehow involved in the regulation of CD4+ cells during ACD responses.Atooppinen ihottuma on krooninen allerginen ihosairaus jota sairastaville saattaa kehittyä myöhemmin myös muita allergioita ja astmaa. Allerginen kosketusihottuma puolestaan on yksi merkittävimmistä ammattitaudeista. Tässä väitöskirjassa on tutkittu joitakin mekanismeja, jotka vaikuttavat näiden tautien syntyyn ja ylläpitoon. Atooppisen ihottuman tautimallissa tulehdusreaktio saadaan aikaan ihon kautta tapahtuvan allergeenialtistuksen avulla. Tämä aiheuttaa tulehdussolujen kulkeutumista ihoon sekä lisää allergiaan liittyvien Th2-tyypin tulehdusvälittäjäaineiden ja IgE-luokan vasta-aineiden määrää. Tässä väitöskirjassa selvitettiin, että erityisesti atooppista ihottumaa sairastavien iholla esiintyvän Staphylococcus aureus -bakteerin tuottama enterotoksiini B (SEB) merkittävästi pahentaa allergeenin aiheuttamaa ihotulehdusta ja lisäksi aikaansaa Th1 tyypin välittäjäaineiden tuottoa, joilla uskotaan olevan merkitystä taudin kroonistumisessa. Siksi bakteeri-infektioiden hallinta onkin tärkeää atooppista ihottumaa sairastavien hoidossa. Säätely T-solut säätelevät tulehdusreaktioiden voimakkuutta. Me selvitimme säätely-T-solujen roolia sekä atooppisessa ihottumassa että kosketusallergiassa hyödyntäen hiirikantaa, joilta säätely T-solut voidaan väliaikaisesti poistaa. Atooppista ihottumaa sairastavien ihon pintakerros on usein vaurioitunut kutinan aiheuttamasta raapimisesta tai geneettisestä mutaatiosta johtuen. Tutkimuksessamme havaitsimme, että säätely-T-solujen poissaollessa jo lievä ihovaurio aiheutti normaalihiirtä voimakkaamman ihotulehduksen. Allergeenialtistus pahensi tulehdusta entisestään, lisäten erityisesti Th2 tyypin välittäjäaineiden ja IgE luokan vasta-aineiden määrää. Lisäksi, kun allergeenia annosteltiin hiiren keuhkoihin aikapisteessä, jolloin säätely-T-solujen määrä oli jo palautunut normaaliksi, voitiin havaita pahentunut tulehdus keuhkoissa normaalihiiriin verrattuna mikä viittaa siihen, että heikentyneellä säätely-T-solujen toiminnalla saattaa olla pitkäaikaisia vaikutuksia. Allergisen kosketusihottuman mallissa ihotulehdus aiheutetaan kahdessa vaiheessa. Herkistysvaiheessa muodostuu allergeenia tunnistavia muistisoluja, mutta ei ihotulehdusta. Elisitaatiovaiheessa allergeenin annostelu iholle aiheuttaa tyypillisen kosketusallergiareaktion. Selvitimme säätely-T-solujen roolia näissä kahdessa eri vaiheessa. Säätely-T-solujen poistaminen herkistysvaiheessa johti merkittävästi pahentuneeseen ihotulehdukseen, kun taas poisto juuri ennen elisitaatiovaihetta ei vaikuttanut millään tavalla tulehdusvasteeseen ensimmäisten 24 tunnin aikana. Sen sijaan tulehdusreaktion lopettaminen viivästyi merkittävästi molemmissa ryhmissä, todennäköisesti siitä syystä, että säätely-T-solut eivät kulkeutuneet ihoon. Säätely-T-solujen toiminnalla on siis merkittävä rooli sekä atooppisen ihottuman että allergisen kosketusihottuman tulehdusreaktion synnyssä ja/tai tulehduksen voimakkuuden ja pituuden säätelyssä. CCR4 on kemokiinireseptori, jota yhdessä kemokiinireseptori CCR10:n kanssa tarvitaan T-solujen kulkeutumisessa ihoon. Hiirillä, joilta puuttuu kemokiinireseptori CCR4, kehittyy odotusten vastaisesti pahentunut allerginen kosketusihottuma normaalihiireen verrattuna. Havaitsimme, että ns. auttaja-T-solut jakaantuivat nopeammin CCR4-/- hiiressä, viitaten siihen, että CCR4 reseptorilla on jokin rooli näiden solujen jakautumisen säätelyssä

FASCIA Method in the Assessment of Lymphocyte Mitogen Responses in the Laboratory Diagnostics of Primary Immunodeficiencies

Peer reviewe

Complex 2B4 Regulation of Mast Cells and Eosinophils in Murine Allergic Inflammation

The cell surface molecule 2B4 (CD244) is an important regulator of lymphocyte activation, and its role in antiviral immunity and lymphoproliferative disorders is well established. Although it is also expressed on mast cells (MCs) and eosinophils (Eos), the functions of 2B4 on these allergy-orchestrating cells remain unclear. We therefore investigated the role of 2B4 on murine MCs and Eos, particularly how this molecule affects allergic and nonallergic inflammatory processes involving these effector cells. Experiments in bone marrow–derived cultures revealed an inhibitory effect for 2B4 in MC degranulation, but also an opposing stimulatory effect in eosinophil migration and delayed activation. Murine disease models supported the dual 2B4 function: In 2B4-/- mice with nonallergic peritonitis and mild atopic dermatitis (AD), modest infiltrates of Eos into the peritoneum and skin (respectively) confirmed that 2B4 boosts eosinophil trafficking. In a chronic AD model, 2B4-/- mice showed overdegranulated MCs, confirming the inhibiting 2B4 effect on MC activation. This multifunctional 2B4 profile unfolded in inflammation resembles a similar mixed effect of 2B4 in natural killer cells. Taken together, our findings provide evidence for physiological 2B4 stimulatory/inhibitory effects in MCs and Eos, pointing to a complex role for 2B4 in allergy

Assembly of Peripheral Actomyosin Bundles in Epithelial Cells Is Dependent on the CaMKK2/AMPK Pathway

Summary Defects in the maintenance of intercellular junctions are associated with loss of epithelial barrier function and consequent pathological conditions, including invasive cancers. Epithelial integrity is dependent on actomyosin bundles at adherens junctions, but the origin of these junctional bundles is incompletely understood. Here we show that peripheral actomyosin bundles can be generated from a specific actin stress fiber subtype, transverse arcs, through their lateral fusion at cell-cell contacts. Importantly, we find that assembly and maintenance of peripheral actomyosin bundles are dependent on the mechanosensitive CaMKK2/AMPK signaling pathway and that inhibition of this route leads to disruption of tension-maintaining actomyosin bundles and re-growth of stress fiber precursors. This results in redistribution of cellular forces, defects in monolayer integrity, and loss of epithelial identity. These data provide evidence that the mechanosensitive CaMKK2/AMPK pathway is critical for the maintenance of peripheral actomyosin bundles and thus dictates cell-cell junctions through cellular force distribution.Peer reviewe

Aortan dissekoituma - päivystyksen musta joutsen

Vertaisarvioitu. English abstract.Aortan dissekoituminen on henkeä uhkaava tilanne, jossa aortan seinämäkerrokset irtoavat toisistaan sisäkalvossa tapahtuneen repeämän vuoksi. Klassinen oire on äkillisesti alkava ja dissekoituman edetessä paikkaa vaihtava rintakipu. Tämän oireen puuttuessa diagnoosiin pääsy voi olla haasteellista, sillä oireet tulevat useista eri elinjärjestelmistä dissekoituman sijainnin ja etenemisen mukaisesti. Kuvaamme kaksi potilastapausta, joissa molemmissa klassinen oirekuva puuttui

Immune-microbiota interaction in Finnish and Russian Karelia young people with high and low allergy prevalence

Background After the Second World War, the population living in the Karelian region was strictly divided by the "iron curtain" between Finland and Russia. This resulted in different lifestyle, standard of living, and exposure to the environment. Allergic manifestations and sensitization to common allergens have been much more common on the Finnish compared to the Russian side. Objective The remarkable allergy disparity in the Finnish and Russian Karelia calls for immunological explanations. Methods Young people, aged 15-20 years, in the Finnish (n = 69) and Russian (n = 75) Karelia were studied. The impact of genetic variation on the phenotype was studied by a genome-wide association analysis. Differences in gene expression (transcriptome) were explored from the blood mononuclear cells (PBMC) and related to skin and nasal epithelium microbiota and sensitization. Results The genotype differences between the Finnish and Russian populations did not explain the allergy gap. The network of gene expression and skin and nasal microbiota was richer and more diverse in the Russian subjects. When the function of 261 differentially expressed genes was explored, innate immunity pathways were suppressed among Russians compared to Finns. Differences in the gene expression paralleled the microbiota disparity. High Acinetobacter abundance in Russians correlated with suppression of innate immune response. High-total IgE was associated with enhanced anti-viral response in the Finnish but not in the Russian subjects. Conclusions and clinical relevance Young populations living in the Finnish and Russian Karelia show marked differences in genome-wide gene expression and host contrasting skin and nasal epithelium microbiota. The rich gene-microbe network in Russians seems to result in a better-balanced innate immunity and associates with low allergy prevalence.Peer reviewe

Thrombus Aspirates From Patients With Acute Ischemic Stroke Are Infiltrated by Viridans Streptococci

BACKGROUND: Acute ischemic stroke may be due to embolism from ruptured atherosclerotic carotid arteries. DNA of oral bacteria, mainly the viridans streptococci group, has been detected in thrombus aspirates of patients with ischemic stroke as well as in carotid endarterectomy samples. Because viridans streptococci are known to possess thrombogenic properties, we studied whether their presence in thrombus aspirates and in carotid artery specimens can be confirmed using bacterial immunohistochemistry. METHODS AND RESULTS: Thrombus aspirates from 61 patients with ischemic stroke (70.5% men; mean age, 66.8 years) treated with mechanical thrombectomy, as well as carotid endarterectomy samples from 20 symptomatic patients (65.0% men; mean age, 66.2 years) and 48 carotid artery samples from nonstroke autopsy cases (62.5% men; mean age, 66.4 years), were immunostained with an antibody cocktail against 3 species ( Streptococcus sanguinis, Streptococcus mitis, and Streptococcus gordonii) of viridans streptococci. Of the thrombus aspirates, 84.8% were immunopositive for viridans streptococci group bacteria, as were 80.0% of the carotid endarterectomy samples, whereas immunopositivity was observed in 31.3% of the carotid artery samples from nonstroke autopsies. Most streptococci were detected inside neutrophil granulocytes, but there were also remnants of bacterial biofilm as well as free bacterial infiltrates in some samples. CONCLUSIONS: Oral streptococci were found in aspirated thrombi of patients with acute ischemic stroke as well as in carotid artery samples. Our results suggest that viridans streptococci group bacteria may play a role in the pathophysiology of ischemic stroke.Peer reviewe

Transcriptional Repressor HIC1 Contributes to Suppressive Function of Human Induced Regulatory T Cells

Regulatory T (Treg) cells are critical in regulating the immune response. In vitro induced Treg (iTreg) cells have significant potential in clinical medicine. However, applying iTreg cells as therapeutics is complicated by the poor stability of human iTreg cells and their variable suppressive activity. Therefore, it is important to understand the molecular mechanisms of human iTreg cell specification. We identified hypermethylated in cancer 1 (HIC1) as a transcription factor upregulated early during the differentiation of human iTreg cells. Although FOXP3 expression was unaffected, HIC1 deficiency led to a considerable loss of suppression by iTreg cells with a concomitant increase in the expression of effector T cell associated genes. SNPs linked to several immune-mediated disorders were enriched around HIC1 binding sites, and in vitro binding assays indicated that these SNPs may alter the binding of HIC1. Our results suggest that HIC1 is an important contributor to iTreg cell development and function

Circulating cell-free DNA in health and disease - the relationship to health behaviours, ageing phenotypes and metabolomics

Circulating cell-free DNA (cf-DNA) has emerged as a promising biomarker of ageing, tissue damage and cellular stress. However, less is known about health behaviours, ageing phenotypes and metabolic processes that lead to elevated cf-DNA levels. We sought to analyse the relationship of circulating cf-DNA level to age, sex, smoking, physical activity, vegetable consumption, ageing phenotypes (physical functioning, the number of diseases, frailty) and an extensive panel of biomarkers including blood and urine metabolites and inflammatory markers in three human cohorts (N = 5385; 17–82 years). The relationships were assessed using correlation statistics, and linear and penalised regressions (the Lasso), also stratified by sex.cf-DNA levels were significantly higher in men than in women, and especially in middle-aged men and women who smoke, and in older more frail individuals. Correlation statistics of biomarker data showed that cf-DNA level was higher with elevated inflammation (C-reactive protein, interleukin-6), and higher levels of homocysteine, and proportion of red blood cells and lower levels of ascorbic acid. Inflammation (C-reactive protein, glycoprotein acetylation), amino acids (isoleucine, leucine, tyrosine), and ketogenesis (3-hydroxybutyrate) were included in the cf-DNA level-related biomarker profiles in at least two of the cohorts.In conclusion, circulating cf-DNA level is different by sex, and related to health behaviour, health decline and metabolic processes common in health and disease. These results can inform future studies where epidemiological and biological pathways of cf-DNA are to be analysed in details, and for studies evaluating cf-DNA as a potential clinical marker.</p