Lung interstitial macrophages alter dendritic cell functions to prevent airway allergy in mice

The respiratory tract is continuously exposed to both innocuous airborne antigens and immunostimulatory molecules of microbial origin, such as LPS. At low concentrations, airborne LPS can induce a lung DC-driven Th2 cell response to harmless inhaled antigens, thereby promoting allergic asthma. However, only a small fraction of people exposed to environmental LPS develop allergic asthma. What prevents most people from mounting a lung DC-driven Th2 response upon exposure to LPS is not understood. Here we have shown that lung interstitial macrophages (IMs), a cell population with no previously described in vivo function, prevent induction of a Th2 response in mice challenged with LPS and an experimental harmless airborne antigen. IMs, but not alveolar macrophages, were found to produce high levels of IL-10 and to inhibit LPS-induced maturation and migration of DCs loaded with the experimental harmless airborne antigen in an IL-10-dependent manner. We further demonstrated that specific in vivo elimination of IMs led to overt asthmatic reactions to innocuous airborne antigens inhaled with low doses of LPS. This study has revealed a crucial role for IMs in maintaining immune homeostasis in the respiratory tract and provides an explanation for the paradox that although airborne LPS has the ability to promote the induction of Th2 responses by lung DCs, it does not provoke airway allergy under normal conditions.

Anti-CTLA-4 treatment induces IL-10-producing ICOS+ regulatory T cells displaying IDO-dependent anti-inflammatory properties in a mouse model of colitis

BACKGROUND AND AIMS

Cytotoxic T lymphocyte-associated antigen 4 (CTLA-4) has been shown to act as a negative regulator of T cell function and has been implicated in the regulation of T helper 1 (Th1)/Th2 development and the function of regulatory T cells. Tests were carried out to determine whether anti-CTLA-4 treatment would alter the polarisation of naive T cells in vivo.

METHODS

Mice were treated with anti-CTLA-4 monoclonal antibody (mAb) (UC10-4F10) at the time of immunisation or colonic instillation of trinitrobenzene sulfonic acid (TNBS). The cytokines produced by lymph node cells after in vitro antigenic stimulation and the role of indoleamine 2,3 dioxygenase (IDO) and of interleukin-10 (IL-10) were tested, and the survival of mice was monitored.

RESULTS

Injection of anti-CTLA-4 mAb in mice during priming induced the development of adaptive CD4(+) regulatory T cells which expressed high levels of ICOS (inducible co-stimulator), secreted IL-4 and IL-10. This treatment inhibited Th1 memory responses in vivo and repressed experimental intestinal inflammation. The anti-CTLA-4-induced amelioration of disease correlated with IDO expression and infiltration of ICOS(high) Foxp3(+) T cells in the intestine, suggesting that anti-CTLA-4 acted indirectly through the development of regulatory T cells producing IL-10 and inducing IDO.

CONCLUSIONS

These observations emphasise the synergy between IL-10 and IDO as anti-inflammatory agents and highlight anti-CTLA-4 treatment as a potential novel immunotherapeutic approach for inducing adaptive regulatory T cells.

Dendritic cells genetically engineered to express IL-10 induce long-lasting antigen-specific tolerance in experimental asthma

Dendritic cells (DCs) are professional APCs that have a unique capacity to initiate primary immune responses, including tolerogenic responses. We have genetically engineered bone marrow-derived DCs to express the immunosuppressive cytokine IL-10 and tested the ability of these cells to control experimental asthma. A single intratracheal injection of OVA-pulsed IL-10-transduced DCs (OVA-IL-10-DCs) to naive mice before OVA sensitization and challenge prevented all of the cardinal features of airway allergy, namely, eosinophilic airway inflammation, airway hyperreactivity, and production of mucus, Ag-specific Igs, and IL-4. OVA-IL-10-DCs also reversed established experimental asthma and had long-lasting and Ag-specific effects. We furthermore showed, by using IL-10-deficient mice, that host IL-10 is required for mediating the immunomodulatory effects of OVA-IL-10-DCs and demonstrated a significant increase in the percentage of OVA-specific CD4(+)CD25(+)Foxp3(+)IL-10(+) regulatory T cells in the mediastinal lymph nodes of OVA-IL-10-DC-injected mice. Finally, adoptive transfer of CD4(+) mediastinal lymph node T cells from mice injected with OVA-IL-10-DCs protected OVA-sensitized recipients from airway eosinophilia upon OVA provocation. Our study describes a promising strategy to induce long-lasting Ag-specific tolerance in airway allergy.

[The role of thrombin in angiogenesis]

The formation of vasculature is a key step during embryogenesis. The vasculature and the intravascular blood compartment, which uses the former as a means of transportation, develop in a close spatial and temporal relationship. This review discusses the role of the blood coagulation system, particularly thrombin, as a tool to coordinate blood vessel formation. Mouse models indicate that a lack of coagulation factors results in impaired thrombin generation and consequently display a phenotype of disturbed cardiovascular development. Similar phenotypes are present in mouse models of impaired thrombin binding to its cellular receptor PAR1 or of disrupted signaling via G-proteins. Moreover, there is compelling evidence that thrombin signaling in vascular development cannot be explained by a model based only on the classical extrinsic and intrinsic coagulation pathways. As angiogenesis in adults follows the same signaling patterns as in embryos, it is of importance to learn about these pathways, hoping that they may serve as therapeutic targets in cardiovascular disease.

[The role of microparticles in vascular diseases]

Microparticles (MP) are small cell vesicles that are released by activated or apoptotic cells and that are amenable to quantification in peripheral blood. MP consist of the cytoplasm and the cell membrane of their cell of origin, which allows for their assignment to these cells. By the detection of the respected MP one can conclude to the functional status of the cell of origin. It is known that MP confer specific information between cells and contribute to inflammatory and coagulatory processes. They are detectable in many acute and chronic vascular diseases as a surrogate marker for disease activity but also play a role in the pathophysiology of vascular diseases.

Blood clots in the cumulus-oocyte complex predict poor oocyte quality and post-fertilization development

Assessment of oocyte maturity and quality (morphological appearance) at the time of retrieval is difficult as the egg is obscured by a large cumulus mass that hinders adequate scoring. Since no data are available on the possible relationship between the cumulus-oocyte complex (COC) and oocyte morphology, this prospective intracytoplasmic sperm injection study was set up in 87 consecutive patients. COC were grouped according to expansion of both corona radiata and cumulus matrix. Special emphasis was placed on recording morphological anomalies of COC (inclusion of blood clots and amorphous clumps). For all mature ovae, quality was assessed and preimplantation development followed up to blastocyst stage if fertilized. The risk of not harvesting an oocyte was higher in COC with blood clots compared with normal cumulus matrices (P = 0.004). COC expansion did not allow for prediction of either nuclear status or quality of the egg. The presence of blood clots within the cumulus matrix was associated with reduced oocyte quality (dense central granulation), fertilization rate and blastocyst formation, compared with unaffected COC (P < 0.05). It may be postulated that COC showing blood inclusions derive from poor quality follicles, which has a detrimental effect on oocyte quality and further cleavage to blastocyst stage. Consequently, mechanical removal of blood clots cannot rescue the corresponding embryo.

Surface and Bulk Degradation of Teflon® FEP Retrieved from the Hubble Space Telescope Solar Arrays

Teflon® fluorinated ethylene propylene (FEP) is used on the Hubble Space Telescope (HST) as the outer layer of multilayer insulation (MLI) blankets. During space shuttle servicing missions (SM) to HST through thickness cracks were observed in the FEP layers. Material brought to Earth for investigation showed signs of severe degradation. During servicing mission 3B, the 4th servicing mission to HST in March 2002, the second pair of European Space Agency ESA built solar arrays was retrieved and flown back to Earth after 8.25 years in space. Samples of the MLI thermal control material were taken from the solar array drive arm (SADA) and investigated for surface and bulk degradation. The MLI was enveloped around the SADA and thus allowed the examination of FEP degradation in dependence of the orientation of space exposed areas with respect to the Sun. Therefore micrographs of FEP surfaces and fractographs of through thickness cracks were taken and the solar absorptance αS and the normal emittance εN was measured on the entire MLI. Differential scanning calorimetrical analyses as well as electron spectroscopy for chemical analyses were conducted to analyze chemical changes of the bulk polymer and the surface layer, respectively. Tensile properties and mass losses of the space exposed material were evaluated as well. Results of the investigated thermal control material are compared with samples exposed on the ground to thermal cycling, soft X-rays and vacuum ultra-violet radiation as well as to previously reported results on space-exposed FEP. The paper thus gives further insight into the mechanism and processes contributing to the on orbit degradation of Teflon® FEP and correlates the presented data with exposure levels and exposure conditions.

Gerinnungshemmende Therapie des akuten Koronarsyndroms

Das akute Koronarsyndrom ist eine der häufigsten kardialen Erkrankungen. Seine Behandlung stützt sich im Wesentlichen auf Koronarintervention und gerinnungshemmende Therapie. Die thrombozytenaggregationshemmende Therapie besteht zurzeit aus Azetylsalizylsäure und Clopidogrel und ggf. periinterventioneller Glykoprotein-IIb/ IIIa-Blockade. Mit Prasugrel steht ein neuer thrombozytenaggregationshemmender Wirkstoff kurz vor der Einführung in die Klinik.

Bei der antithrombotischen Therapie geht die Entwicklung zu Pharmaka mit Anti-Faktor-Xa-Aktivität (z. B. Fondaparinux) oder direkter Antithrombinwirkung (z. B Bivalirudin). In diesem Übersichtsartikel werden die Entwicklungen der vergangenen Monate auf dem Gebiet der gerinnungshemmenden Therapie des akuten Koronarsyndroms diskutiert.

[Anticoagulation in acute coronary syndrome. An update]

The acute coronary syndrome (ACS) is one of the most frequent diagnoses in cardiology. The therapeutic corner-stones of ACS are PCI (percutaneous coronary intervention) and inhibition of blood coagulation. Current antiplatelet therapy consists of aspirin in combination with clopidogrel and glycoprotein IIb/IIIa blockade if needed. Prasugel is a new antiplatelet agent that is in the process of being approved for routine clinical use. In terms of antithrombotic therapy latest developments focus on drugs with anti-factor Xa activity, such as fondaparinux, or direct anti-thrombin activity, such as bivalirudin. This review discusses latest developments in the field of anti-platelet and anti-thrombotic therapy for ACS.

Die Bedeutung von Mikropartikeln bei vaskulären Erkrankungen

Mikropartikel (MP) sind kleine Zellvesikel, die von Zellen im Rahmen von Aktivierung oder Apoptose freigesetzt werden und im Blut nachweisbar sind. MP bestehen aus Plasma und Zellmembran ihrer Ursprungszelle und können anhand ihrer Oberflächenantigene ihrer Ursprungszelle zugeordnet werden. Durch den Nachweis entsprechender MP kann somit eine Aussage über den Funktionszustand der Ursprungszelle (Aktivierung oder Apoptose) getroffen werden. Mittlerweile ist bekannt, dass MP als Vektoren spezifische biologische Informationen zwischen einzelnen Zellen austauschen können und somit ein wesentliches Bindeglied in der Pathophysiologie inflammatorischer und koagulatorischer Prozesse darstellen. Da viele Gefäßerkrankungen mit inflammatorischen und thrombotischen Prozessen einhergehen, sind MP nachweisbar und bekommen sowohl als Diagnostikum (Surrogatmarker) als auch als pathophysiologischer Baustein vaskulärer Erkrankungen zunehmende Bedeutung.

Die Rolle von Thrombin in der Blutgefäßentwicklung

Die Bildung des Blutgefäßsytems ist ein entscheidender Schritt in der Embryonalentwicklung. Blutgefäßsystem und Blut entwickeln sich in enger räumlicher Nachbarschaft. In dieser Übersichtsarbeit wird die Rolle des Blutgerinnungssystems, inbesondere von Thrombin, als Koordinator der Blutgefäßbildung diskutiert.

In Mausmodellen zeigt sich, dass der Verlust von Gerinnungsfaktoren zu verminderter Thrombinbildung führt und von einer gestörten kardiovaskulären Entwicklung begleitet ist. Ähnliche Phänotypen lassen sich in Tiermodellen beobachten, in denen die Bindung von Thrombin und seinen Zelloberflächenrezeptor PAR-1 oder die anschließende G-Protein-Signalkaskade gestört sind. Darüber hinaus wird deutlich, dass die Thrombinsignalübertragung in der Blutgefäßentwicklung nicht durch das klassische Modell der extrinsischen und intrinsischen Blutgerinnungskaskade erklärbar sind, sondern zahlreiche Quervernetzungen bestehen. Da embryonale und adulte Blutgefäßbildung ähnlichen Mechanismen folgen, ist es entscheidend diese zu verstehen, um neuartige vaskuläre Therapiestrategien entwickeln zu können.

Injection of lipopolysaccharide induces the migration of splenic neutrophils to the T cell area of the white pulp: role of CD14 and CXC chemokines

There is increasing evidence that neutrophils are involved in the regulation of adaptive immunity. We therefore tested whether these cells may colocalize with T lymphocytes in lymphoid organs. Our results demonstrate that administration of the microbial product LPS induces the migration of neutrophils in the spleen from the red pulp and the marginal zone to the area of the white pulp where T cells reside. This movement is CD14-dependent, whereas the recruitment of neutrophils in the peritoneal cavity is increased in the absence of CD14. Our data further suggest the involvement of the chemokine MIP-2 and keratinocyte-derived chemokine and their receptor CXCR2. We conclude that neutrophils may interact with naïve T cells upon infection/inflammation and that the migration of neutrophils in the lymphoid organs and in the periphery is regulated differently by a signal transduced by CD14.

[Is stent thrombosis the new Achilles heel of interventional cardiology? State of the Art clinical trials, causes and approaches for prevention]

Coronary stents are the mainstay of percutaneous coronary intervention. Stent thrombosis is a potentially catastrophic and often life-threatening complication. If it occurs it presents in up to 80% as myocardial infarction, about half of the affected patients die from this complication. The dual antiplatelet therapy has markedly reduced its occurrence. Today, stent thrombosis occurs in <1%, usually as a delayed event; but compared to bare metal stents the overall incidence has not increased in meta-analyses of randomized trials. The advent of drug-eluting stents (DES) has raised concerns regarding the occurrence of delayed stent thrombosis. Delayed arterial wall healing as well as prothrombotic characteristics of the drug eluting stent itself may contribute to stent thrombosis. In order to prevent stent thrombosis a standardized fixed dose antiplatelet therapy with ASA and clopidogrel is recommended. But, their efficacy depends on patient's individual characteristics such drug metabolism. Therefore, individual determination of platelet function in each patient undergoing stent implantation may help to avoid prothrombotic as well as bleeding complications.

Developmental fate of ovoid oocytes

BACKGROUND

Irregularities in composition, thickness and/or color of the zona pellucida may impair optimal function and result in reduced outcome. Anomalies of oocyte shape have not been investigated in detail in this respect.

METHODS

Therefore, all patients attending our clinic within a period of 1 year were screened for the presence of ovoid gametes and the corresponding developmental potential was evaluated. For all elongated gametes, a roundness index (RI; length divided by width) was calculated in order to quantify shape.

RESULTS

RI did not affect fertilizability (P > 0.05). The degree of dysmorphism was found to be related to cleavage pattern. The more ovoid a gamete was, the higher was the risk of the corresponding zygote not cleaving like a tetrahedron (P < 0.01). Abnormal cleavage (a rather flat array of blastomeres) was associated with delayed compaction (P < 0.01) and blastocyst formation (P < 0.001). The quality of blastocysts was not affected at any stage in ovoid concepti (P > 0.05).

CONCLUSIONS

Ovoid oocytes with abnormal cleavage pattern show delayed preimplantation development, probably due to a reduced number of cell-to-cell contacts.

African Trypanosomiasis: Naturally Occurring Regulatory T Cells Favor Trypanotolerance by Limiting Pathology Associated with Sustained Type 1 Inflammation

Tolerance to African trypanosomes requires the production of IFN-gamma in the early stage of infection that triggers the development of classically activated macrophages controlling parasite growth. However, once the first peak of parasitemia has been controlled, down-regulation of the type 1 immune response has been described. In this study, we have evaluated whether regulatory T cells (Tregs) contribute to the limitation of the immune response occurring during Trypanosoma congolense infection and hereby influence the outcome of the disease in trypanotolerant C57BL/6 host. Our data show that Foxp3+ Tregs originating from the naturally occurring Treg pool expanded in the spleen and the liver of infected mice. These cells produced IL-10 and limited the production of IFN-gamma by CD4+ and CD8+ effector T cells. Tregs also down-regulated classical activation of macrophages resulting in reduced TNF-alpha production. The Treg-mediated suppression of the type 1 inflammatory immune response did not hamper parasite clearance, but was beneficial for the host survival by limiting the tissue damages, including liver injury. Collectively, these data suggest a cardinal role for naturally occurring Tregs in the development of a trypanotolerant phenotype during African trypanosomiasis.