Microscale arrays for the profiling of start and stop signals coordinating human-neutrophil swarming.

Neutrophil swarms protect healthy tissues by sealing off sites of infection. In the absence of swarming, microbial invasion of surrounding tissues can result in severe infections. Recent observations in animal models have shown that swarming requires rapid neutrophil responses and well-choreographed neutrophil migration patterns. However, in animal models physical access to the molecular signals coordinating neutrophil activities during swarming is limited. Here, we report the development and validation of large microscale arrays of zymosan-particle clusters for the study of human neutrophils during swarming ex vivo. We characterized the synchronized swarming of human neutrophils under the guidance of neutrophil-released chemokines, and measured the mediators released at different phases of human-neutrophil swarming against targets simulating infections. We found that the network of mediators coordinating human-neutrophil swarming includes start and stop signals, proteolytic enzymes and enzyme inhibitors, as well as modulators of activation of other immune and non-immune cells. We also show that the swarming behavior of neutrophils from patients following major trauma is deficient and gives rise to smaller swarms than those of neutrophils from healthy individuals

Migration of CXCR3+ T regulatory cells towards the chemokine IP-10

Introduction Chemotaxis is the process where cells migrate under influence of specific chemoattractant mediators (chemokines) toward an extracellular gradient. The study of in vitro chemotaxis with traditional methods has its limitations, however a new promising method to study cell migration on single cell level is with microfluidics. I designed a microfluidic model to study migratory behavior of a CD4+ T regulatory cell subset (Tregs). Tregs are essential for tempering immune reactions. The traffic of T regulatory cells to local inflammatory sites is now known to be important for suppression and tolerance, therefore migration of Tregs from blood to the inflamed tissue is essential for the suppression of alloimmunity. Cell migration is promoted by chemokines; a well-established T cell chemoattractant is interferon-inducible protein 10 (IP-10). One of its ligands, CXCR3, is expressed on activated human CD4+ T cells and is important in T effector cell trafficking. The presence of CXCR3+ T cells and IP-10 within allograft biopsies is associated with rejection. However, the Briscoe lab recently found that CXCR3 is also expressed on Tregs. With help of microfluidics I proof that CXCR3+ Tregs migrate to the chemokine IP-10. Materials and Methods For my migration studies I isolated human CD4+CD25+CD127dim/- cells from PBMC and stained them with an anti-CXCR3 antibody. With FACS I sorted the Tregs into CXCR3+ and CXCR3- populations. I introduced these populations in our microfluidic device, which consist out of a microfluidic network array of up to 450 parallel micro channels connected to one main channel. The device was primed with a chemokine solution of IP-10 (100 nM) and fibronectin (250 nM). The cells were monitored for 3 hours using time-lapse microscopy. Results I designed a microfluidic device that enabled us to study cell migratory behavior on a single cell level. Using my device we found that CXCR3+ Tregs migrate towards IP-10 and that the directional persistence of CXCR3+ is significantly greater (P<0.01) than that observed for CXCR3- Tregs. Discussion The lab demonstrates that CXCR3 is expressed on human FOXP3+CD4+ T cell subsets. I developed a microfluidic device for quantitative analysis of CD4+ T cell migration and used it to identify the function of CXCR3 on a T regulatory subset. Microfluidics was used successfully to show that CXCR3+ Tregs migrate persistently towards IP-10, suggesting that CXCR3 facilitates the peripheral migration of Tregs into allografts where they have potential to suppress ongoing rejection.

Redenen voor het combineren van meerdere banen

Werkenden die twee of meer banen combineren, vormen geen uitzondering op de Nederlandse arbeidsmarkt. Een analyse op een representatieve steekproef van de werkzame beroepsbevolking toont wie er banen combineren en wat de belangrijkste redenen daarvoor zijn

Multi-jobbing als employability-strategie

Werkenden voor wie de werksituatie bestaat uit een combinatie van twee of meer banen, vormen geen uitzondering op de Nederlandse arbeidsmarkt. Toch weten we nog weinig over de motieven voor het combineren van meerdere banen – ofwel multi-jobbing. Dit artikel betreft een kwalitatieve verkenning onder twintig multi-jobbers van 45 jaar en ouder die recentelijk een transitie hebben gemaakt van één baan in loondienst naar meerdere banen in loondienst of een baan gecombineerd met zzp-schap. Multi-jobbing als alternatieve (tussen)vorm van arbeidsmobiliteit is nog een erg onderbelicht onderzoeksthema en relevant voor werkenden in een latere loopbaanfase waarvoor reguliere baanmobiliteit veel minder vanzelfsprekend is. We beschrijven de diverse push- en pullmotieven voor het aangaan van een combinatiebaan of hybride baan die duiden op multi-jobbing als noodsituatie, ideaalsituatie of overgangssituatie. De studie maakt verder duidelijk dat een groot deel van de geïnterviewden een tweede baan bewust gebruikt als persoonlijke employability-strategie. We bediscussiëren multi-jobbing als arbeidsmarktgedrag dat in een latere loopbaanfase inspeelt op de onzekerheid die gepaard gaat met mobiliteit

Targeting complement activation in brain-dead donors improves renal function after transplantation.

Kidneys recovered from brain-dead donors have inferior outcomes after transplantation compared to kidneys from living donors. Since complement activation plays an important role in renal transplant related injury, targeting complement activation in brain-dead donors might improve renal function after transplantation. Brain death (BD) was induced in Fisher rats by inflation of an epidurally placed balloon catheter and ventilated for 6h. BD animals were treated with soluble complement receptor 1 (sCR1) 1h before or 1h after BD. Kidney transplantation was performed and 7 days after transplantation animals were sacrificed. Plasma creatinine and urea were measured at days 0, 1, 3, 5 and 7 after transplantation. Renal function was significantly better at day 1 after transplantation in recipients receiving a sCR1 pre-treated donor kidney compared to recipients of a non-treated donor graft. Also treatment with sCR1, 1h after the diagnosis of BD, resulted in a better renal function after transplantation. Gene expression of IL-6, IL-1beta and TGF-beta were significantly lower in renal allografts recovered from treated donors. This study shows that targeting complement activation, during BD in the donor, leads to an improved renal function after transplantation in the recipient