Die Rolle von Butyrophilin subfamily 2 member A2 (Btn2a2) bei der Reifung von T Zellen

Butyrophilins (BTNs) and Butyrophilin-like molecules (BTNLs) constitute a family of transmembrane molecules with structural and functional resemblance to the B7 family of molecules. Recently, a co-inhibitory role of Btn2a2 on ab T cell activation has been recognized. In addition, Btn2a2 deficient mice exhibited enhanced effector T cell responses to immunization and exacerbated disease in a CD4+ T cell-dependent experimental autoimmune encephalomyelitis (EAE) model. These effects were attributed to hematopoietic antigen presenting cells (APCs), and Btn2a2 was co-regulated with MHC class II genes. However, the generality of such observations, the exact role of Btn2a2 in T cell activation, as well as the cell type responsible for these effects remain unknown. Therefore, in this study, we aimed to characterize the effects of Btn2a2 in health and disease and delineate its expression pattern. We found that, rather than showing increased susceptibility to induced autoimmune disease in murine models of experimental lupus and arthritis, Btn2a2-/- mice showed spontaneous autoimmunity that occurred with increasing age. This was manifested by the production of autoantibodies against nuclear antigens and severe lymphocytic organ intrusions in lacrimal and salivary glands, which were accompanied by physiological impairments, such as decreased production of lacrimal fluid. In addition, Btn2a2-/- mice mounted enhanced immune responses against intestinal pathogens, resulting in superior clearance. Moreover, we show that under physiological conditions, Btn2a2 expression was mainly restricted to the thymus, and this was not due to hematopoietic APCs but almost exclusively to thymic epithelial cells (TECs). Expression was dependent on RANKL and, at least in medullary TECs (mTECs), was CIITA-mediated, suggesting co-regulation with MHC II genes. Mechanistically, we reveal co-inhibitory properties of Btn2a2 on thymocytes as Btn2a2-Fc interfered with activation-induced apoptosis of DP and SP thymocytes in vitro, while the lack of Btn2a2 resulted in higher TCR signaling and activation of OT-II thymocytes, as shown by elevated CD5 levels, a direct measure of TCR signal strength. Consistently, the peripheral T cell pool of Btn2a2-/- mice was is skewed towards CD5hi cells, and these cells showed increased basal TCR phosphorylation in steady-state. Further, we show that Btn2a2-/- mice display reduced T cell numbers, a state that is associated with lymphopenia-induced proliferation and correlates with autoimmunity in mice and humans. Thus, we conclude that a CD5-skewed, activation-prone T cell repertoire incident to a proliferation-promoting, lymphopenic environment, perhaps in concert with another, yet unknown factor, precipitate in autoimmunity.Butyrophiline (BTNs) und Butyrophilin-ähnliche Moleküle (BTNLs) bilden eine Familie von Transmembranmolekülen mit struktureller und funktioneller Ähnlichkeit mit der B7-Familie von Molekülen. Kürzlich konnte eine inhibitorische Rolle von Btn2a2 auf ab T Zellen in vitro festgestellt werden. Darüber hinaus zeigten Btn2a2-deziente Mäuse verstärkte Effektor-T-Zell-Reaktionen auf Immunisierung und einen verschlimmerten Krankheitsverlauf im Modell der CD4+ T-Zell-abhängigen experimentellen Autoimmun- Enzephalomyelitis (EAE). Diese Effekte wurden hämatopoetischen Antigen-präsentierenden Zellen (APCs) zugeschrieben, und Btn2a2 wurde zusammen mit MHC-Klasse-II-Genen reguliert. Die Allgemeingültigkeit dieser Beobachtungen, die genaue Rolle von Btn2a2 bei der T-Zell-Aktivierung sowie der für diese Effekte verantwortliche Zelltyp sind jedoch nach wie vor unbekannt. In dieser Studie wollten wir daher die Effekte von Btn2a2 in Gesundheit und Krankheit charakterisieren und sein Expressionsmuster untersuchen. Obwohl Btn2a2-/- Mäuse keine erhöhte Anfälligkeit für induzierte Autoimmunkrankheiten in experimentellen Lupus- und Arthritis-Modellen zeigten, konnten wir eine spontane Autoimmunität bei Btn2a2-/- Mäusen feststellen, die mit zunehmendem Alter auftrat. Diese äußerte sich in der Produktion von Autoantikörpern gegen nukleäre Antigene sowie schweren lymphozytären Organintrusionen in Tränen- und Speicheldrüsen, die mit physiologischen Beeinträchtigungen einhergingen, wie beispielsweise einer verminderten Produktion von Tränenflüssigkeit. Darüber hinaus zeigten Btn2a2-/- Mäuse eine verstärkte Immunantwort gegen Darmpathogene, die mit einer verbesserten Clearance einherging. Zudem konnten wir zeigen, dass unter physiologischen Bedingungen Btn2a2-Expression hauptsächlich auf den Thymus begrenzt war, und diese war nicht etwa auf hämatopoietische Antigen-präsentierende Zellen zurückzuführen sondern fast ausschließlich auf Thymusepithelzellen (TECs). Reguliert wurde die Expression durch RANKL und war, zumindest in medullären TECs (mTECs), CIITA-vermittelt, was auf eine Co-Regulation mit MHC II Gene hindeutet. Mechanistisch beobachteten wir co-inhibitorische Eigenschaften von Btn2a2 auf Thymozyten, denn Btn2a2-Fc konnte die aktivierungsinduzierte Apoptose von DP- und SP-Thymozyten in vitro beeinträchten, während das Fehlen von Btn2a2 zu einem höheren TCR-Signal und stärkeren Aktivierung von OT-II-Thymozyten führte, wie durch erhöhte CD5 Levels, einem direkten Maß für die TCR-Signalstärke, gezeigt wird. Im Einklang damit haben wir festgestellt, dass der periphere T-Zell-Pool von Btn2a2-/- Mäusen einen erhöhten Anteil an CD5hi T Zellen aufweist, und diese Zellen zeigten eine erhöhte basale TCR-Phosphorylierung im Steady-State. Außerdem zeigen wir, dass Btn2a2-/- Mäuse eine reduzierte T-Zellzahl aufweisen, ein Zustand, der mit Lymphopenieinduzierter Proliferation einhergeht und mit Autoimmunität bei Mäusen und Menschen korreliert. Aus diesen Beobachtungen schließen wir, dass ein CD5-verschobenes, aktivierungsanfälliges T-Zell-Repertoire in einer proliferationsfördernden, lymphopenischen Umgebung, vielleicht in Verbindung mit einem anderen, noch unbekannten Faktor, Autoimmunität auslöst

The Prevalence and Clinical Correlates of an Auscultatory Gap in Systemic Sclerosis Patients

Introduction. Accurate blood pressure (BP) measurement is essential to the diagnosis and management of hypertension in patients with systemic sclerosis (SSc) to help prevent renal and cardiovascular complications. The presence of an auscultatory gap during manual BP measurement—the temporary disappearance of the Korotkoff sounds during cuff deflation—leads to a potentially important underestimate of systolic BP if undetected. Objectives. Since the presence of an auscultatory gap is frequently associated with increased vascular stiffness, we investigated its presence and correlates in 50 consecutive SSc patients. Methods. For each patient, BP was measured sequentially using three different approaches performed in the same order. Results. Sixteen of 50 patients (32%) had an auscultatory gap which if undetected would have resulted in clinically important underestimates of systolic BP in 4 patients. The presence of an auscultatory gap was statistically associated with the presence of antibodies to RNA polymerase III (P<0.0068) and SSc diagnosis type (P<0.01). Conclusions. Our study demonstrates that auscultatory gaps are relatively common in SSc and correlate with markers for SSc vasculopathy. If undetected auscultatory gaps may result in clinically important underestimation of BP. Thus, electronic oscillometric BP may be preferred in SSc patients

Measuring power consumption in an integrated circuit

A method for determining power consumption of a power domain within an integrated circuit is presented. In a first step, a local power supply impedance profile (Z(f)) of this power domain is determined. Subsequently, a local time-resolved power supply voltage (U(t)) is measured while a well-defined periodic activity is executed in power domain. A set of time-domain measured voltage data (U(t)) is thus accumulated and transformed into the frequency domain to yield a voltage spectrum (U(f)). A current spectrum I(t) is calculated from this voltage profile (U(f)) by using the power supply impedance profile Z(f) of this power domain as I(t)=Ff −1{U(f)/Z(f)}. Finally, a time-resolved power consumption spectrum P(t) is determined from measured voltage spectrum U(t)) and calculated current spectrum (I(t)). This power consumption (P(t)) may be compared with a reference (Pref(t)) to verify whether power consumption within power domain matches expectations

An in vivo gene delivery approach for the isolation of reasonable numbers of type 2 innate lymphoid cells

Group 2 innate lymphoid cells (ILC2s) are a recently recognized subset of innate lymphocytes with crucial role in mucosal immunity and tissue homeostasis. Over the past decade, substantial advances in our understanding of ILC2 biology have established them as an essential element in innate and adaptive immunity. However, their relatively low abundance and laborious purification from mucosal tissues make their study difficult. Moreover, due to a lack of an ILC2-specific Cre mouse-line, adoptive transfer of ILC2s into ILC-deficient hosts is inevitable. Herein we describe an in-depth protocol for the induction, isolation, and expansion of murine ILC2s. By combining an in vivo gene delivery approach to boost ILC2 numbers and a cell culture strategy to expand isolated cells, large quantities of highly pure ILC2s can be obtained. The isolated cells maintain their phenotype and can be used for subsequent cell transfer or in vitro studies. In comparison to previous protocols, this approach is cost-effective and efficient with potential yield of more than 20 million ILC2s isolated per mouse. • Group 2 innate lymphoid cells (ILC2s) are extensively studied in mouse models and humans in recent years. • Low abundance of ILC2s and current lack of specific ILC2 knockout mice makes in vivo research challenging. • This method allows high and pure ILC2 numbers for in vitro or adoptive in vivo transfer experiments

Aircraft Wake Vortex Scenarios Simulation Package - WakeScene

Wake-vortex advisory systems and modifications of ATC procedures that aim at increasing airport capacity without compromising safety have been developed in recent years. Prior to the introduction of such systems the associated risks must be assessed. The WakeScene (Wake Vortex Scenarios Simulation) Package allows to assess the encounter probability behind different wake-vortex generating aircraft during approach and landing. WakeScene consists of modules that model traffic mix, aircraft trajectories, meteorological conditions, wake vortex evolution, and potential hazard area. This manuscript introduces the operating sequence of WakeScene, the employed sub-models and data bases, the simulation environment and evaluation tools together with the so far accomplished validation work. Examples of WakeScene applications and an outlook on further developments of the software package conclude the report

The Role of Dietary Fiber in Rheumatoid Arthritis Patients: A Feasibility Study

Short-chain fatty acids are microbial metabolites that have been shown to be key regulators of the gut–joint axis in animal models. In humans, microbial dysbiosis was observed in rheumatoid arthritis (RA) patients as well as in those at-risk to develop RA, and is thought to be an environmental trigger for the development of clinical disease. At the same time, diet has a proven impact on maintaining intestinal microbial homeostasis. Given this association, we performed a feasibility study in RA patients using high-fiber dietary supplementation with the objective to restore microbial homeostasis and promote the secretion of beneficial immunomodulatory microbial metabolites. RA patients (n = 36) under routine care received daily high-fiber bars or cereals for 28 days. Clinical assessments and laboratory analysis of immune parameters in blood and stool samples from RA patients were done before and after the high-fiber dietary supplementation. We observed an increase in circulating regulatory T cell numbers, favorable Th1/Th17 ratios, as well as decreased markers of bone erosion in RA patients after 28 days of dietary intervention. Furthermore, patient-related outcomes of RA improved. Based on these results, we conclude that controlled clinical studies of high-fiber dietary interventions could be a viable approach to supplement or complement current pharmacological treatment strategies

RANKL-Induced Btn2a2 – A T Cell Immunomodulatory Molecule – During Osteoclast Differentiation Fine-Tunes Bone Resorption

Butyrophilins, which are members of the extended B7 family of immunoregulators structurally related to the B7 family, have diverse functions on immune cells as co-stimulatory and co-inhibitory molecules. Despite recent advances in the understanding on butyrophilins’ role on adaptive immune cells during infectious or autoimmune diseases, nothing is known about their role in bone homeostasis. Here, we analyzed the role of one specific butyrophilin, namely Btn2a2, as we have recently shown that Btn2a2 is expressed on the monocyte/macrophage lineage that also gives rise to bone degrading osteoclasts. We found that expression of Btn2a2 on monocytes and pre-osteoclasts is upregulated by the receptor activator of nuclear factor κ-B ligand (RANKL), an essential protein required for osteoclast formation. Interestingly, in Btn2a2-deficient osteoclasts, typical osteoclast marker genes (Nfatc1, cathepsin K, TRAP, and RANK) were downregulated following RANKL stimulation. In vitro osteoclast assays resulted in decreased TRAP positive osteoclast numbers in Btn2a2-deficient cells. However, Btn2a2-deficient osteoclasts revealed abnormal fusion processes shown by their increased size. In vivo steady state µCT and histological analysis of bone architecture in complete Btn2a2-deficient mice showed differences in bone parameters further highlighting the fine-tuning effect of BTN2a2. Moreover, in rheumatoid arthritis patients and experimental arthritis, we detected significantly decreased serum levels of the secreted soluble Btn2a2 protein. Taken together, we identified the involvement of the immunomodulatory molecule Btn2a2 in osteoclast differentiation with potential future implications in basic and translational osteoimmunology