CpG-Motive im Mausmodell für allergisches Asthma – Einfluß immunstimulatorischer DNA-Sequenzen auf die Entwicklung der allergischen Sensibilisierung und bronchialen Hyperreagibilität

Die Prävalenz und Inzidenz allergischer Erkrankungen haben in den industrialisierten Ländern in den vergangenen Jahrzehnten stetig zugenommen. Für die Entwicklung des allergischen Phänotyps sind genetische und Umwelteinflüsse im weitesten Sinne verantwortlich. Die „Hygiene-Hypothese“ geht davon aus, daß mikrobielle Stimuli allergie-protektiv wirken. Insbesondere bakterielle Antigene und bakterielle DNA-Sequenzen mit einem zentralen, unmethylierten Cytosin/Guanin Motiv (CpG) konnten für immunostimulatorische Effekte im Sinne einer anti-allergischen Immunantwort (Th1) verantwortlich gemacht werden. In der vorliegenden Arbeit wurde untersucht, ob ein CpG-Allergen-Adsorbat (ISS) in der Lage ist, den allergischen (Th2-) Phänotyp im Sinne einer Th1-Protektion zu beeinflussen. Dazu wurde schrittweise ein Mausmodell etabliert, das die Beurteilung der ISS-Wirkung auf klinische und immunologische Parameter erlaubt. In einem prophylaktischen Ansatz, bei dem die Behandlung vor der Auslösung der Allergiesymptome stattfand, ist ISS in der Lage, die Zahl der Entzündungszellen sowie die der mukusproduzierenden Becherzellen zu verringern, die Entstehung bronchialer Hyperreagibilität (AHR) zu unterdrücken und Th1-assoziierte IgG2a Antikörper zu stärken. Nach Auslösen der Symptome konnte die Wirksamkeit der CpG-Behandlung im Sinne einer sekundären Prävention erneut belegt werden. Die Sekretion des Th1-Leitzytokins IFN-γ wird erhöht. In einem Therapieansatz, der der klinischen Situation eines Allergikers mit Asthma nahe kommt, kann ISS die AHR unterdrücken und die IgG2a Titer anheben. Auf Zytokinebene wird ein Wechsel von Th2 nach Th1 nicht erreicht. Die Ergebnisse zeigen, daß die ISS-Adsorbat-Immuntherapie einen vielversprechenden Ansatz zur Behandlung des allergischen Asthma darstellt, wenn auch die beobachteten Effekte nicht auf eine isolierte „Verdrängung“ einer Th2- durch eine Th1- Immunantwort zurückzuführen sind. Vielmehr scheinen sich die erwünschten Th1-Effekte parallel zur bestehenden Th2-Antwort zu entwickeln. Das hier vorgestellte Mausmodell bietet erstmals die Möglichkeit, Immunmodulationswirkungen in einer kliniknahen Situation zu untersuchen und eröffnet damit neue Perspektiven zur Erforschung dieses innovativen Therapiekonzeptes

Treatment of Allergic Airway Inflammation and Hyperresponsiveness by Antisense-Induced Local Blockade of Gata-3 Expression

Recent studies in transgenic mice have revealed that expression of a dominant negative form of the transcription factor GATA-3 in T cells can prevent T helper cell type 2 (Th2)-mediated allergic airway inflammation in mice. However, it remains unclear whether GATA-3 plays a role in the effector phase of allergic airway inflammation and whether antagonizing the expression and/or function of GATA-3 can be used for the therapy of allergic airway inflammation and hyperresponsiveness. Here, we analyzed the effects of locally antagonizing GATA-3 function in a murine model of asthma. We could suppress GATA-3 expression in interleukin (IL)-4–producing T cells in vitro and in vivo by an antisense phosphorothioate oligonucleotide overlapping the translation start site of GATA-3, whereas nonsense control oligonucleotides were virtually inactive. In a murine model of asthma associated with allergic pulmonary inflammation and hyperresponsiveness in ovalbumin (OVA)-sensitized mice, local intranasal administration of fluorescein isothiocyanate–labeled GATA-3 antisense oligonucleotides led to DNA uptake in lung cells associated with a reduction of intracellular GATA-3 expression. Such intrapulmonary blockade of GATA-3 expression caused an abrogation of signs of lung inflammation including infiltration of eosinophils and Th2 cytokine production. Furthermore, treatment with antisense but not nonsense oligonucleotides induced a significant reduction of airway hyperresponsiveness in OVA-sensitized mice to levels comparable to saline-treated control mice, as assessed by both enhanced pause (PenH) responses and pulmonary resistance determined by body plethysmography. These data indicate a critical role for GATA-3 in the effector phase of a murine asthma model and suggest that local delivery of GATA-3 antisense oligonucleotides may be a novel approach for the treatment of airway hyperresponsiveness such as in asthma. This approach has the potential advantage of suppressing the expression of various proinflammatory Th2 cytokines simultaneously rather than suppressing the activity of a single cytokine

Monitoring immune modulation by nutrition in the general population: identifying and substantiating effects on human health

Optimal functioning of the immune system is crucial to human health, and nutrition is one of the major exogenous factors modulating different aspects of immune function. Currently, no single marker is available to predict the effect of a dietary intervention on different aspects of immune function. To provide further guidance on the assessment and interpretation of the modulation of immune functions due to nutrition in the general population, International Life Sciences Institute Europe commissioned a group of experts from academia, government and the food industry to prepare a guidance document. A draft of this paper was refined at a workshop involving additional experts. First, the expert group defined criteria to evaluate the usefulness of immune function markers. Over seventy-five markers were scored within the context of three distinct immune system functions: defence against pathogens; avoidance or mitigation of allergy; control of low-grade (metabolic) inflammation. The most useful markers were subsequently classified depending on whether they by themselves signify clinical relevance and/or involvement of immune function. Next, five theoretical scenarios were drafted describing potential changes in the values of markers compared with a relevant reference range. Finally, all elements were combined, providing a framework to aid the design and interpretation of studies assessing the effects of nutrition on immune function. This stepwise approach offers a clear rationale for selecting markers for future trials and provides a framework for the interpretation of outcomes. A similar stepwise approach may also be useful to rationalise the selection and interpretation of markers for other physiological processes critical to the maintenance of health and well-bein

A proposal for early dosing regimens in heart transplant patients receiving thymoglobulin and calcineurin inhibition

There is currently no consensus regarding the dose or duration of rabbit antithymocyte globulin (rATG) induction in different types of heart transplant patients, or the timing and intensity of initial calcineurin inhibitor (CNI) therapy in rATG-treated individuals. Based on limited data and personal experience, the authors propose an approach to rATG dosing and initial CNI administration. Usually rATG is initiated immediately after exclusion of primary graft failure, although intraoperative initiation may be appropriate in specific cases. A total rATG dose of 4.5 to 7.5 mg/kg is advisable, tailored within that range according to immunologic risk and adjusted according to immune monitoring. Lower doses (eg, 3.0 mg/kg) of rATG can be used in patients at low immunological risk, or 1.5 to 2.5 mg/kg for patients with infection on mechanical circulatory support. The timing of CNI introduction is dictated by renal recovery, varying between day 3 and day 0 after heart transplantation, and the initial target exposure is influenced by immunological risk and presence of infection. Rabbit antithymocyte globulin and CNI dosing should not overlap except in high-risk cases. There is a clear need for more studies to define the optimal dosing regimens for rATG and early CNI exposure according to risk profile in heart transplantation

Role of nerve growth factor in a mouse model of allergic airway inflammation and asthma

The role of nerve growth factor (NGF), a potent mediator acting in the development and differentitation of both neuronal and immune cells, was examined in a mouse model of allergic asthma. NGF‐positive cells were detected in the inflammatory infiltrate of the lung and enhanced levels of NGF were detected in serum and broncho‐alveolar lavage fluids. Mononuclear cells in inflamed airway mucosa as well as broncho‐alveolar macrophages were identified as one source of NGF production. Splenic mononuclear cells from allergen‐sensitized mice produced NGF in response to allergen. They responded to exogenously added NGF with a dose‐dependent increase in IL‐4 and IL‐5 production and augmented IgE and IgG1 synthesis. In contrast, IFN‐γ and IgG2a levels remained unaffected. The effects were NGF specific, since they could be blocked by an anti‐NGF‐antibody. Nasal application of anti‐NGF to allergen‐sensitized mice significantly reduced IL‐4 and prevented development of airway hyperreactivity. These results show that allergic airway inflammation is accompanied by enhanced local NGF production that acts as an amplifier for Th2 effector functions and plays an important role in the development of airway hyperreactivity. Therefore it is suggested that NGF may serve as a link between the immune and nerve system