Regulatorische Foxp3+CD4+ T-Zellen sind essentiell für das Gleichgewicht des intestinalen Immunsystems. Eine Einschränkung ihrer Suppressionsfunktion wird bei Patienten mit Immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX)-Syndrom beobachtet und führt im Tiermodell zu lymphoproliferativen Erkrankungen und intestinalen Entzündungen. Von entscheidender Bedeutung für Homöostase und Suppressionsfunktion regulatorischer T-Zellen ist das Signalmolekül Interleukin-2 (IL-2). Im Gegensatz zu Effektor-T-Zellen exprimieren Foxp3+CD4+ T-Zellen den hochaffinen IL-2-Rezeptor αβγ konstitutiv. IL-2 wird von regulatorischen T-Zellen nicht in relevanten Mengen exprimiert. Sie sind somit auf von anderen Zellen sezerniertes IL-2 angewiesen. In der vorliegenden Arbeit wird gezeigt, dass im Tiermodell regulatorische Foxp3+CD4+ T-Zellen durch Applikation eines IL-2/anti-IL-2-Antikörperkomplex nicht nur in mesenterialen Lymphknoten und Milz, sondern auch lokal in der Lamina propria mucosae des Kolons der Versuchstiere expandiert werden. Als relevante Quelle von IL-2 in situ könnten aktivierte proliferierende T-Zellen dienen. Um dies näher zu untersuchen, wurde die Proteinexpression proliferierender Einzelzellen mittels Matrix assisted laser desorption/ionisation-Time of flight-Massenspektrometrie-Imaging (MALDI-Imaging) analysiert. Es gelang die Identifikation präferentiell in lymphoiden Geweben exprimierter Peptidmassen. Obwohl die Einzelzellanalyse mittels MALDI-Imaging prinzipiell möglich erscheint, ist ein Nachweis von Zytokinen wie IL-2 derzeit aufgrund fehlender Sensitivität im Proteinmassebereich zwischen 10kDa und 20kDa nicht möglich. Die therapeutischen Möglichkeiten der Expansion regulatorischer Foxp3+ T-Zellen durch stabile IL-2-Rezeptor-Agonisten und die Rolle von IL-2 für die intestinale Immunregulation sollten weiter untersucht werden.:Bibliographische Beschreibung 3 Inhaltsverzeichnis 4 Abkürzungsverzeichnis 7 1. Einleitung 9 1.1. Störung der Barrierefunktion des intestinalen Immunsystems als Ursache chronisch entzündlicher Darmerkrankungen 9 1.2. Foxp3+ regulatorische T-Zellen 10 1.3. Die Rolle von Interleukin-2 für regulatorische T-Zellen 11 1.4. Signaltransduktion in regulatorischen T-Zellen als Grundlage ihrer selektiven Expansion und Induktion 12 1.5. Möglichkeiten der präferentiellen Expansion regulatorischer T-Zellen 15 1.5.1. Expansion regulatorischer T-Zellen durch Agonisten des hochaffinen IL-2-Rezeptors 15 1.5.2. Induktion regulatorischer T-Zellen durch TGF-β 16 1.5.3. Expansion regulatorischer T-Zellen durch Rapamycin (Sirolimus) 17 1.5.4. Expansion regulatorischer T-Zellen durch UVB-Bestrahlung bzw. Vitamin D-Rezeptor-Agonisten 18 1.5.5. Expansion regulatorischer T-Zellen durch Histon-Deacetylaseinhibitoren 19 1.6. Suppression von Effektor-T-Zellen durch regulatorische T-Zellen 20 1.6.1. Zellkontaktabhängige Mechanismen 20 1.6.2. Zellkontaktunabhängige Mechanismen 22 1.7. Matrix assisted laser desorption ionisation-Time of flight-Massenspektromie (MALDI-TOF-MS): Bedeutung und Funktion 23 1.8. Zielstellung 25 2. Materialien und Methoden 26 2.1. Versuchstiere 26 2.2. IL-2/IgG2b-Fusionsprotein-Vorexperiment 26 2.2.1. Induktion von 2,4,6-Trinitrobenzensulfonsäure (TNBS)-Kolitis 26 2.2.2. Durchführung des IL-2/IgG2b-Fusionsprotein-Vorexperimentes 26 2.3. Durchführung des IL-2/anti-IL-2-Antikörperkomplex-Experiments 27 2.4. Durchflusszytometrie 27 2.5. Histologische Färbungen 28 2.5.1. Probenvorbereitung 28 2.5.2. Hämatoxylin/Eosin (HE) Färbung 29 2.5.3. Immunfluoreszenz-Färbungen 29 2.5.4. Ki67-Schnellfärbung 30 2.5.5. Mikroskopie und Photographie 30 2.6. Histologische Auswertungen 31 2.6.1. Kolitis-Score 31 2.6.2. Bildanalyse 31 2.6.3. Validierung der automatischen Bildanalyse mittels CellProfiler 33 2.7. MALDI-Imaging 35 2.7.1. Probenvorbereitung für MALDI-Imaging 35 2.7.2. Analyse der Peptidexpression in Gewebeschnitten mittels MALDI-Imaging 36 2.8. Statistische Auswertungen 36 2.8.1. Statistische Tests 36 2.8.2. Berechnung der zu erwartenden Zahl von Kontakten zwischen Ki67+ und Foxp3+ Zellen 36 3. Ergebnisse 38 3.1. Design des IL-2/anti-IL-2-Antikörperkomplex Experimentes 38 3.2. Mit IL-2/anti-IL-2-Antikörperkomplex behandelte Tiere zeigen Splenomegalie und Lymphadenomegalie 40 3.3. Behandlung mit einem IL-2/anti-IL-2-Antikörperkomplex führt zur präferentiellen Expansion regulatorischer T-Zellen in mesenterialen Lymphknoten und Milz 41 3.4. Behandlung mit IL-2/anti-IL-2-Antikörperkomplex führt nicht zu Kolitis 43 3.5. Behandlung mit IL-2/anti-IL-2-Antikörperkomplex führt zur präferentiellen Expansion regulatorischer T-Zellen in der Lamina propria mucosae 45 3.6. IL-2/anti-IL-2-Antikörperkomplex steigert die Proliferation regulatorischer T-Zellen in der Lamina propria mucosae und lymphoiden Follikeln des Kolons 47 3.7. Regulatorische T-Zellen sind nach Behandlung mit IL-2/anti-IL-2-Antikörperkomplex weiter mit proliferierenden Zellen assoziiert. 50 3.8. MALDI-Imaging als Möglichkeit der Proteinexpressionsanalyse in situ 52 3.8.1. Vergleich der Proteinexpression in verschiedenen Geweben von Ileum und Zäkum mit der Expression in Thymus und mesenterialem Lymphknoten 55 3.8.2. MALDI-Imaging nach Schnellfärbung Ki67+ Zellen mit Streptavidin 63 3.8.3. Analyse der Massenspektren von Einzelzellen mittels MALDI-Imaging 66 4. Diskussion 68 4.1. Applikation von IL-2/anti-IL-2-Antikörperkomplex hat keine fatalen Nebenwirkungen 68 4.2. IL-2/anti-IL-2-Antikörperkomplex führt zur präferentiellen Expansion regulatorischer T-Zellen in mesenterialen Lymphknoten, Milz und Kolon 70 4.3. IL-10 als wichtiger Vermittler der Suppressionsaktivität durch IL-2/anti-IL-2-Antikörperkomplex expandierter regulatorischer T-Zellen 71 4.4. Expansion regulatorischer T-Zellen beim Menschen: Voraussetzungen und Chancen 72 4.5. Regulatorische T-Zellen akkumulieren an proliferierenden Zellen 73 4.6. Nachweis spezifischer Massen in Gewebe und Einzelzellen mittels MALDI-Imaging 74 5. Zusammenfassung 80 Literaturverzeichnis 83 Publikationen 90 Erklärung über die eigenständige Abfassung der Arbeit 97 Lebenslauf 98 Danksagungen 99

Thymic stromal lymphopoietin (TSLP) produced by epithelial cells acts on dendritic cells (DCs) to drive differentiation of TH2-cells, and is therefore important in allergic disease pathogenesis. However, DCs themselves make significant amounts of TSLP in response to microbial products, but little is known about the key downstream signals that induce and modulate this TSLP secretion from human DCs. We show that human monocyte derived DC (mDC) secretion of TSLP in response to Candida albicans and β-glucans requires dectin-1, Syk, NF-κB, and p38 MAPK signaling. In addition, TSLP production by mDCs is greatly enhanced by IL-1β, but not TNF-α, in contrast to epithelial cells. Furthermore, TSLP secretion is significantly increased by signals emanating from the endoplasmic reticulum (ER) stress response, specifically the unfolded protein response sensors, inositol-requiring transmembrane kinase/endonuclease 1 and protein kinase R-like ER kinase, which are activated by dectin-1 stimulation. Thus, TSLP production by mDCs requires the integration of signals from dectin-1, the IL-1 receptor, and ER stress signaling pathways. Autocrine TSLP production is likely to play a role in mDC-controlled immune responses at sites removed from epithelial cell production of the cytokine, such as lymphoid tissue.

Tim-3 and PD-1 are powerful immunoinhibitory molecules involved in immune tolerance, autoimmune responses, and antitumor or antiviral immune evasion. A current model for Tim-3 regulation during immune responses suggests a divergent function, such that Tim-3 acts synergistically with TLR signaling pathways in innate immune cells to promote inflammation, yet the same molecule terminates Th1 immunity in adaptive immune cells. To better understand how Tim-3 might be functioning in innate immune responses, we examined the kinetics of Tim-3 expression in human CD14 + M/M 4 in relation to expression of IL-12, a key cytokine in the transition of innate to adaptive immunity. Here, we show that Tim-3 is constitutively expressed on unstimulated peripheral blood CD14 + monocytes but decreases rapidly upon TLR stimulation. Conversely, IL-12 expression is low in these cells but increases rapidly in CD14 + M/M.J, in correlation with the decrease in Tim-3. Blocking Tim-3 signaling or silencing Tim-3 expression led to a significant increase in TLR-mediated IL-12 production, as well as a decrease in activation-induced up-regula-tion of the immunoinhibitor, PD-1; TNF-a production was not altered significantly, but IL-10 production was increased. These results suggest that Tim-3 has a role as a regulator of pro- and anti-inflammatory innate immune responses.

Tim-3 has been linked to several inflammatory diseases by regulation on both adaptive and innate immunities. Here, we assessed the augmented expression of Tim-3 in brain tissue of ischemia-reperfusion mice and PBMCs of ischemic stroke (IS) patients. The augmented expression of Tim-3 significantly correlated with abnormal lipid levels. In vitro studies showed that plasma from ischemic stroke patients induced Tim-3 expression in THP- 1 cells. More importantly, our results revealed a significant correlation of Tim-3 expression on CD4 + T cells with systemic IL-17 in patients with ischemic stroke. Consistently, we also found a positive correlation of Tim-3 expression on CD14 + monocytes and serum TNF-a in IS patients. Collectively, augmented expression of Tim-3 may play an important role in the pathogenesis of ischemic stroke by regulation of proinflammatory cytokines. Further studies will give us new insights on the pathogenesis of ischemic stroke and potentially provide a new target at the medical therapy.

AimsInnate immune and inflammatory responses are involved in myocardial ischaemia/reperfusion (I/R) injury. The interleukin-1 receptor (IL-1R)-mediated, MyD88-dependent nuclear factor kappa B (NF-κB) activation pathway plays an important role in the induction of innate immunity and inflammation. However, the role of the IL-1R-MyD88 pathway in myocardial I/R injury has not been thoroughly investigated. We hypothesized that inhibition of the interaction of IL-1R with MyD88 will attenuate myocardial ischaemic injury through reducing inflammatory responses.Methods and resultsMale C57BL/6 mice were subjected to myocardial ischaemia (45 min) followed by reperfusion (4 h). In the treatment group, after mice were subjected to ischaemia (45 min), the TIR/BB-loop mimetic (AS-1), which inhibits the interaction of IL-1R with MyD88, was administered immediately before reperfusion. Hearts were harvested and cellular proteins were isolated for immunoprecipitation and immunoblotting. AS-1 administration significantly decreased infarct size by 32.92 compared with the untreated I/R group. Ejection fraction and fractional shortening in AS-1-treated mice were also significantly increased by 18.0 and 25.6, respectively, compared with the untreated I/R group. AS-1 administration significantly decreased the I/R-increased interaction between IL-1R and MyD88, attenuated the I/R-increased NF-κB binding activity, and reduced levels of inflammatory cytokines and adhesion molecules in the myocardium compared with the untreated I/R group. In addition, AS-1 administration significantly decreased myocardial myeloperoxidase activity by 23.6 and neutrophil infiltration in the myocardium compared with the untreated I/R group.ConclusionThe results demonstrated an important role for the IL-1R-mediated MyD88-dependent signalling pathway in myocardial I/R injury. The data suggest that modulation of the IL-1R/MyD88 interaction could be a strategy for reducing myocardial ischaemic injury.

Maternal immune activation (MIA) can affect fetal brain development and thus behavior of young and adult offspring. Reports have shown that increased Interleukin-6 (IL-6) in the maternal serum plays a key role in altering fetal brain development, and may impair social behaviors in the offspring. Interestingly, these effects could be attenuated by blocking IL-6. The current study investigated the effects of luteolin, a citrus bioflavonoid, and its structural analog, diosmin, on IL-6 induced JAK2/STAT3 (Janus tyrosine kinase-2/signal transducer and activator of transcription-3) phosphorylation and signaling as well as behavioral phenotypes of MIA offspring. Luteolin and diosmin inhibited neuronal JAK2/STAT3 phosphorylation both in vitro and in vivo following IL-6 challenge as well as significantly diminishing behavioral deficits in social interaction. Importantly, our results showed that diosmin (10 mg/kg day) was able to block the STAT3 signal pathway; significantly opposing MIA-induced abnormal behavior and neuropathological abnormalities in MIA/adult offspring. Diosmin's molecular inhibition of JAK2/STAT3 pathway may underlie the attenuation of abnormal social interaction in IL-6/MIA adult offspring.

Background: Diminished cytokine production in infancy has been associated with an increased risk for allergen sensitization and early-life wheeze. Objective: We sought to assess the effect of low cytokine production in the first year of life on the development of wheeze through age 13 years. Methods: Cytokine production (IFN-γ and IL-2) by mitogen-stimulated mononuclear cells was determined from peripheral blood samples (9.4 months, n = 118) in a subset of healthy infants enrolled in the Tucson Children's Respiratory Study. The occurrence of wheeze during the previous year was ascertained at ages 2, 3, 6, 8, 11, and 13 years by means of questionnaire. Relative risk for wheeze was computed with generalized estimating equations. Results: The risk of wheezing between 2 and 13 years was significantly higher for subjects with low 9-month IFN-γ production (relative risk, 2.29; 95% CI, 1.35-3.89) and borderline significant for those with intermediate IFN-γ production (relative risk, 1.59; 95% CI, 0.95-2.68) compared with those who produced high levels of IFN-γ (P value for linear association = .002). Nine-month IL-2 production was unrelated to wheeze. In relation to complex wheezing phenotypes, 9-month IFN-γ production was inversely related to toddler wheeze (occurring only before age 6 years, P = .03) and chronic wheeze (occurring before and after age 6 years, P = .007) but not school-age wheeze (occurring only after age 6 years, P = .06). Conclusion: The results suggest that characteristics of the immune system present during the first year of life can anticipate the likelihood of development of episodes of airway obstruction characterized by wheezing. Clinical implications: Immune susceptibility to asthma is established very early during postnatal life.

The interaction between CD40 ligand (CD154) expressed on activated T cells and its receptor, CD40, has been shown to play a role in the onset and maintenance of autoimmune inflammation. Recent studies suggest that CD154+T cells also contribute to the regulation of atherogenesis due to their capacity to activate CD40+cells of the vasculature, including vascular smooth muscle cells (VSMC). The present study evaluated the signalling events initiated through CD40 ligation which culminate in VSMC chemokine production. CD40 ligation resulted in the phosphorylation/activation of mitogen-activated protein kinases (MAPKs), extracellular signal-regulated kinases 1 and 2 (ERK1/2), and p38, but not c-jun N-terminal kinase. Inhibition of both ERK1/2 and p38 activity abrogated CD40 stimulation of IL-8 and MCP-1 production. CD40-mediated induction of chemokines also showed dependence on the Src family kinase activity. The Src kinase inhibitor, PP2, was found to inhibit CD40-induced phosphorylation of ERK1/2 as well as activation of IκB kinase. An evaluation of Src kinases that may be important in CD40 signalling identified Lyn as a potential candidate. These data indicate that CD40 signalling in VSMC activates a Src family kinase-initiated pathway that results in the induction of MAPK activities required for successful induction of chemokine synthesis.

Objective: Determine if aspirin inhibits the IL-1β-stimulated expression of inducible nitric oxide synthase (iNOS), nitric oxide (NO), and prostaglandin E2 (PGE2) in rat ovarian dispersates cultured in vitro. Design: Prospective, controlled in vitro study. Setting: Academic research laboratory. Animals: Ovaries collected from immature rats. Intervention(s): Ovaries were collected from immature rats and enzymatically dispersed. Ovarian dispersates were placed into plates containing media alone or media supplemented with IL-1β (100 U/mL) and varying concentrations of aspirin (0, 1, 3, 5 and 10 mM). Ovarian dispersates were cultured in a humidified environment of 5% CO2 in air at 37°C for 24 or 48 hours. Main Outcome Measure(s): Twenty-four- and 48-hour iNOS, nitrite (a stable metabolite of NO), and PGE2 levels were determined from ovarian dispersates cultured in vitro. Result(s): Administration of IL-1β increased nitrite and PGE2 levels over that observed in the control group after culture of ovarian dispersates for 24 and 48 hours. Aspirin dose dependently reduced the IL-1β-stimulated increase in nitrite production from ovarian dispersates after culture for 24 and 48 hours. Aspirin completely (24 hours) or dose dependently (48 hours) prevented the IL-β-stimulated increase in PGE2. Coadministration of IL-1β and aspirin (10 mM) attenuates IL-1β-stimulated iNOS expression after culture for 24 and 48 hours. Conclusion(s): Aspirin significantly inhibits the IL-1β-stimulated expression of iNOS, NO, and PGE2 in ovarian dispersates cultured in vitro.

We defined how blood-derived vitronectin (VTN) rapidly and potently activates leukemia inhibitory factor (LIF) and pro-inflammatory interleukin 6 (IL-6) in vitro and after vascular injury in the brain. Treatment with VTN (but not fibrinogen, fibronectin, laminin-111 or collagen-I) substantially increased LIF and IL-6 within 4 h in C6-astroglioma cells, while VTN-/- mouse plasma was less effective than that from wild-type mice. LIF and IL-6 were induced by intracerebral injection of recombinant human (rh)VTN in mice, but induction seen upon intracerebral hemorrhage was less in VTN-/- mice than in wild-type littermates. In vitro, VTNeffects were inhibited by RGD, αvβ3 and αvβ5 integrin-blocking peptides and antibodies. VTN activated focal adhesion kinase (FAK; also known as PTK2), whereas pharmacological- or siRNA-mediated inhibition of FAK, but not PYK2, reduced the expression of LIF and IL-6 in C6 and endothelial cells and after traumatic cell injury.Dominant-negative FAK (Y397F) reduced the amount of injury-induced LIF and IL-6. Pharmacological inhibition or knockdown of uPAR (also known as PLAUR), which binds VTN, also reduced cytokine expression, possibly through a common target of uPAR and integrins. We propose that VTN leakage into tissues promotes inflammation. Integrin-FAKsignaling is therefore a novel IL-6 and LIF regulation mechanism relevant to the inflammation and stem cell fields.