Tip-DC development during parasitic infection is regulated by IL-10 and requires CCL2/CCR2, IFN-gamma and MyD88 signaling

The development of classically activated monocytic cells (M1) is a prerequisite for effective elimination of parasites, including African trypanosomes. However, persistent activation of M1 that produce pathogenic molecules such as TNF and NO contributes to the development of trypanosome infection-associated tissue injury including liver cell necrosis in experimental mouse models. Aiming to identify mechanisms involved in regulation of M1 activity, we have recently documented that during Trypanosoma brucei infection, CD11b⁺Ly6C⁺CD11c⁺ TNF and iNOS producing DCs (Tip-DCs) represent the major pathogenic M1 liver subpopulation. By using gene expression analyses, KO mice and cytokine neutralizing antibodies, we show here that the conversion of CD11b⁺Ly6C⁺ monocytic cells to pathogenic Tip-DCs in the liver of T. brucei infected mice consists of a three-step process including (i) a CCR2-dependent but CCR5- and Mif-independent step crucial for emigration of CD11b⁺Ly6C⁺ monocytic cells from the bone marrow but dispensable for their blood to liver migration; (ii) a differentiation step of liver CD11b⁺Ly6C⁺ monocytic cells to immature inflammatory DCs (CD11c⁺ but CD80/CD86/MHC-II^low) which is IFN-γ and MyD88 signaling independent; and (iii) a maturation step of inflammatory DCs to functional (CD80/CD86/MHC-II^high) TNF and NO producing Tip-DCs which is IFN-γ and MyD88 signaling dependent. Moreover, IL-10 could limit CCR2-mediated egression of CD11b⁺Ly6C⁺ monocytic cells from the bone marrow by limiting Ccl2 expression by liver monocytic cells, as well as their differentiation and maturation to Tip-DCs in the liver, showing that IL-10 works at multiple levels to dampen Tip-DC mediated pathogenicity during T. brucei infection. A wide spectrum of liver diseases associates with alteration of monocyte recruitment, phenotype or function, which could be modulated by IL-10. Therefore, investigating the contribution of recruited monocytes to African trypanosome induced liver injury could potentially identify new targets to treat hepatic inflammation in general, and during parasite infection in particular.

Most infections are associated with host inflammatory responses that can result in multiple organ failure and death. It is therefore essential to understand the mechanisms balancing host immune response and tissue damage. Mouse models of African trypanosome infection represent valuable tools to study the mechanisms contributing to the inflammatory (pathogenic) or anti-inflammatory (anti-pathogenic) immune response. We recently identified TNF and NO producing DCs (Tip-DCs) as major contributors to liver pathogenicity in Trypanosoma brucei infected mice. Herein, the role of different chemokine and cytokines in the generation of Tip-DCs was investigated. Tip-DCs originated from bone marrow derived monocytes that egressed to the blood in a CCR2 chemokine receptor dependent manner. Then, monocytes extravasated to inflamed liver where IFN-γ and MyD88 signaling promoted their maturation to Tip-DCs. Both the egression of monocytes from bone marrow and their IFN-γ/MyD88 dependent maturation to Tip-DCs was counteracted by IL-10, hereby reducing liver pathogenicity. Liver injury, affecting millions of persons worldwide with often lethal consequences, frequently results from uncontrolled activation of recruited monocyte-derived cells that can be modulated by IL-10. Thus, the mechanisms regulating liver immunopathogenicity during parasitic infection identified herein could lead to new therapeutic policies in the field of hepatic inflammation.

Domain-wall movement control in Co/Au multilayers by He(+)-ion-bombardment-induced lateral coercivity gradients

Defined perpendicular anisotropy gradients in the Co sublayers of a [Co(0.6  nm)/Au(2  nm)](3) sputter-deposited multilayer have been introduced by light ion bombardment through a wedged Au stopper layer. Within such a layer system, domain walls between up- and down-magnetized areas are controllably movable by an external perpendicular homogeneous magnetic field. This method and layer system is very promising for a controlled magnetic particle transport within the stray fields of the moving domain walls.

Incidence and outcome of traumatic brain injury in an urban area in Western Europe over 10 years

INTRODUCTION

Valid epidemiological data on incidence and outcome of traumatic brain injury (TBI) show great variability. A study on incidence, severity and outcome of TBI was conducted in an urban area of one million inhabitants.

MATERIALS AND METHODS

130,000 prehospital emergencies were screened for TBI.

INCLUSION CRITERIA

Glasgow Coma Scale (GCS) score <or=8 and/or Abbreviated Injury Scale for head injuries (AIS(head)) score >or=2 with confirmed TBI via appropriate diagnostics.

RESULTS

Annual incidence was 7.3/100,000. Overall mortality rate was 45.8%: 182 (28%) were prehospital deaths, 116 (17.8%) patients died in hospital. Two hundred and fourteen of 352 (60.8%) surviving patients were sufficiently rehabilitated at discharge [Glasgow Outcome Scale (GOS) score = 1], but 138 patients (39.2%) survived with persisting deficits. GOS was associated with initial GCS and AIS(head).

CONCLUSION

The incidence of TBI was lower compared to the literature. The overall mortality was high, especially prehospital and early in-hospital mortality rates.

Delayed neuronal death after brain trauma involves p53-dependent inhibition of NF-kappaB transcriptional activity

Acute and chronic neurodegeneration, for example, following brain injury or Alzheimer's disease, is characterized by programmed death of neuronal cells. The present study addresses the role and interaction of p53- and NF-kappaB-dependent mechanisms in delayed neurodegeneration following traumatic brain injury (TBI). After experimental TBI in mice p53 rapidly accumulated in the injured brain tissue and translocated to the nucleus of damaged neurons, whereas NF-kappaB transcriptional activity simultaneously declined. Post-traumatic neurodegeneration correlated with the increase in p53 levels and was significantly reduced by the selective p53 inhibitor pifithrin-alpha (PFT). Strikingly, this protective effect was observed even when PFT treatment was delayed up to 6 h after trauma. Inhibition of p53 activity resulted in the concomitant increase in NF-kappaB transcriptional activity and upregulation of NF-kappaB-target proteins, for example X-chromosomal-linked inhibitor of apoptosis (XIAP). It is interesting to note that inhibition of XIAP abolished the neuroprotective effects of PFT in cultured neurons exposed to camptothecin, glutamate, or oxygen glucose deprivation. In conclusion, delayed neuronal cell death after brain trauma is mediated by p53-dependent mechanisms that involve inhibition of NF-kappaB transcriptional activity. Hence, p53 inhibition provides a promising approach for the treatment of acute brain injury, since it blocks apoptotic pathways and concomitantly triggers survival signaling with a therapeutic window relevant for clinical applications.

Tumor necrosis factor alpha- and inducible nitric oxide synthase-producing dendritic cells are rapidly recruited to the bladder in urinary tract infection but are dispensable for bacterial clearance

The role of dendritic cells (DC) in urinary tract infections (UTI) is unknown. These cells contribute directly to the innate defense against various viral and bacterial infections. Here, we studied their role in UTI using an experimental model induced by transurethral instillation of the uropathogenic Escherichia coli (UPEC) strain 536 into C57BL/6 mice. While few DC were found in the uninfected bladder, many had been recruited after 24 h, mostly to the submucosa and uroepithelium. They expressed markers of activation and maturation and exhibited the CD11b+ F4/80+ CD8- Gr-1- myeloid subtype. Also, tumor necrosis factor alpha (TNF-alpha)- and inducible nitric oxide synthase (iNOS)-producing CD11bINT DC (Tip-DC) were detected, which recently were proposed to be critical in the defense against bacterial infections. However, Tip-DC-deficient CCR2-/- mice did not show reduced clearance of UPEC from the infected bladder. Moreover, clearance was also unimpaired in CD11c-DTR mice depleted of all DC by injection of diphtheria toxin. This may be explained by the abundance of granulocytes and of iNOS- and TNF-alpha-producing non-DC that were able to replace Tip-DC functionality. These findings demonstrate that some of the abundant DC recruited in UTI contributed innate immune effector functions, which were, however, dispensable in the microenvironment of the bladder.

Robot-Assisted Craniotomy

In the Special Research Centre 414 of the German Research Funding (DFG, Bonn) a system for robot-assisted cranial surgery was developed. It is designed for the accurate and safe execution of craniotomies and repositioning of bone pieces. The system is intended for use in the surgical therapy of craniosynostosis. Preoperatively, CT imaging is performed. In a computerized planning system the position and shape of the intended craniotomy is intuitively planned on a virtual model of the patient's skull. Intraoperatively, after conventional removal of the covering soft tissue, the robot performs the craniotomy autonomously. Extensive testing in phantom studies and animal tests confirmed the reliability and accuracy of the system. A thorough risk analysis of the system was performed. In this paper, the first clinical use of the system on a patient is described and the clinical importance is discussed.

Heat shock protein 60 is released in immune-mediated glomerulonephritis and aggravates disease: in vivo evidence for an immunologic danger signal

Heat shock proteins (Hsp) are ubiquitous intracellular proteins that can be released in various forms of cellular stress. Some Hsp, such as Hsp60, have been shown to stimulate directly T cell-mediated immune responses in vitro. Here, it is demonstrated that Hsp60 is released from the kidneys and excreted into the urine of mice with nephrotoxic nephritis (NTN), a model of rapidly progressive glomerulonephritis. For examining the functional relevance of Hsp60 release, this protein was injected into mice with subnephritogenic NTN, in which only transient proteinuria and minimal organ damage occur that do not progress to terminal kidney failure. Injection of Hsp60 strikingly aggravated disease, as evidenced by global glomerular necrosis, tubulointerstitial damage, and complete anuria after 10 to 12 d. This effect was mediated neither by endotoxin contaminations of Hsp60 nor by autologous antibodies. It was strictly T cell dependent but not associated with a systemic Th1/Th2 shift. Thus, Hsp60 is an endogenous mediator stimulating immune effector mechanisms that contribute to the progression of NTN. These findings demonstrate in vivo that Hsp60 fulfills criteria of immunologic danger signals and suggest that such signals may be involved in immune-mediated kidney disease.

Identification and functional characterization of dendritic cells in the healthy murine kidney and in experimental glomerulonephritis

The kidney tubulointerstitium contains numerous bone marrow-derived antigen-presenting cells, which are often referred to as resident tissue macrophages, although several previous studies had demonstrated characteristics of dendritic cells (DC). In this study, we describe a subset of tubulointerstitial cells expressing the DC marker CD11c. A protocol was established to isolate these cells for in vitro analysis. Renal CD11c(+) cells resembled splenic DC, but not peritoneal macrophages, in morphology, lysosomal content, phagocytic activity, microbicidal effector functions, expression of T cell costimulatory molecules, and ability to activate T cells. Nevertheless, many CD11c(+) renal cells expressed low or intermediate levels of F4/80 and CD11b, indicating that both markers are not absolutely specific for macrophages in the kidney. Subpopulations of renal DC could be distinguished based on their expression of MHC class II and costimulatory molecules and may represent different maturation stages. In nephrotoxic glomerulonephritis, increased numbers of CD11c(+) cells showing DC functionality were found in the tubulointerstitium. Focal accumulation was seen within tubulointerstitial mononuclear infiltrates and adjacent to, but not within, inflamed glomeruli. These results are the first to identify and characterize renal CD11c(+) cells as DC and to demonstrate marked changes in experimental glomerulonephritis.

Alpha 5 subunit-containing GABAA receptors affect the dynamic range of mouse hippocampal kainate-induced gamma frequency oscillations in vitro

Though all in vitro models of gamma frequency network oscillations are critically dependent on GABAA receptor-mediated synaptic transmission little is known about the specific role played by different subtypes of GABAA receptor. Strong expression of the alpha5 subunit of the GABAA receptor is restricted to few brain regions, amongst them the hippocampal dendritic layers. Receptors containing this subunit may be expressed on the extrasynaptic membrane of principal cells and can mediate a tonic GABAA conductance. Using hippocampal slices of wild-type (WT) and alpha5-/- mice we investigated the role of alpha5 subunits in the generation of kainate-induced gamma frequency oscillations (20-80 Hz). The change in power of the oscillations evoked in CA3 by increasing network drive (kainate, 50-400 nm) was significantly greater in alpha5-/- than in WT slices. However, the change in frequency of gamma oscillations with increasing network drive seen in WT slices was absent in alpha5-/- slices. Raising the concentration of extracellular GABA by bathing slices in the GABA transaminase inhibitor vigabatrin and blocking uptake with tiagabine reduced the power of gamma oscillations more in WT slices than alpha5-/- slices (43%versus 15%). The data suggest that loss of this GABAA receptor subunit alters the dynamic profile of gamma oscillations to changes in network drive, possibly via actions of GABA at extrasynaptic receptors.

[Cadaver study: robot-assisted cranial resection and implantation of titanium plates]

A processing chain for the prefabrication of individual titanium implants for cranioplasty was developed at the Ruhr-University Bochum. In patients with tumours a simultaneous resection of cranial bone and insertion of the individual implant is desirable. At first resection templates were used for this. New developments aim at a preoperative definition of resection trajectories for surgical robots corresponding to both the planning of the resection and the implant. This study used ovine cadaver skulls for robot resection experiments. The results demonstrate possible applications, limitations and necessary prerequisites in robot assisted cranial surgery.