α1-Antitrypsin attenuates acute rejection of orthotopic murine lung allografts

Background

α1-Antitrypsin (AAT) is an acute phase glycoprotein, a multifunctional protein with proteinase inhibitory, anti-inflammatory and cytoprotective properties. Both preclinical and clinical experiences show that the therapy with plasma purified AAT is beneficial for a broad spectrum of inflammatory conditions. The potential effects of AAT therapy have recently been highlighted in lung transplantation (LuTx) as well.

Methods

We used a murine fully mismatched orthotopic single LuTx model (BALB/CJ as donors and C57BL/6 as recipients). Human AAT preparations (5 mg, n = 10) or vehicle (n = 5) were injected to the recipients subcutaneously prior to and intraperitoneally immediately after the LuTx. No immune suppressive drugs were administered. Three days after the transplantation, the mice were sacrificed, and biological samples were assessed.

Results

Histological analysis revealed significantly more severe acute rejection in the transplanted lungs of controls than in AAT treated mice (p < 0.05). The proportion of neutrophil granulocytes, B cells and the total T helper cell populations did not differ between two groups. There was no significant difference in serum CXCL1 (KC) levels. However, when compared to controls, human AAT was detectable in the serum of mice treated with AAT and these mice had a higher serum anti-elastase activity, and significantly lower proportion of Th1 and Th17 among all Th cells. Cleaved caspase-3-positive cells were scarce but significantly less abundant in allografts from recipients treated with AAT as compared to those treated with vehicle.

Conclusion

Therapy with AAT suppresses the acute rejection after LuTx in a mouse model. The beneficial effects seem to involve anti-protease and immunomodulatory activities of AAT.

Identification of distinct secretory patterns and their regulatory networks of ischemia versus reperfusion phases in clinical heart transplantation

BACKGROUND

Ischemia/reperfusion injury (IRI) is associated with inflammatory responses contributing to the development of primary graft dysfunction (PGD) and rejection. Here, we investigated the pathophysiology of IRI and the early phase after heart transplantation (HTx) regarding its cytokine/chemokine and endothelial networks.

METHODS

Using multiplex technology, we assessed protein concentrations in plasma samples of HTx recipients (n = 11) pre-, postoperatively, 24 h and 3 weeks after HTx. The same proteins were quantified in organ storage solutions at the end of heart storage (n = 10). Unsupervised cluster, principal component analysis (PCA), K-nearest neighbor (KNN) network classifier analysis, ANOVA and Spearman correlation analyses were performed to identify specific patterns for IRI and individual kinetics of important soluble factors in HTx.

RESULTS

Unique patterns of soluble factors were identified in plasma of HTx patients. KNN analysis defined IL-10, IL-6, sIL-6Rα, IL-1RA, IL-16, sVEGFR-1, IGFBP-1, HGF and sHer-2 as strongest signals directly post-Tx declining 24 hrs after HTx. By contrast, MIF, osteopontin (OPN), sVCAM-1 and sICAM-1, IGFBP-1, SCGF-ß, HGF were highly enriched in organ storage solutions, reflecting distinct ischemic (storage solution) vs. reperfusion (plasma) signatures.

CONCLUSIONS

We identified specific inflammatory signatures for ischemic vs. reperfusion phases of HTx, associated with pro- as well as anti-inflammatory and endothelial biomarker candidates for IRI. These signatures might help to identify potential danger factors and their networks at both the ex situ (ischemic) as well as the reperfusion phase in the recipient after implantation.

Delayed non-myeloablative irradiation to induce long-term allograft acceptance in a large animal lung transplantation model

We previously induced long-term allograft acceptance in an allogeneic lung transplantation (LTx) model in miniature swine using perioperative non-myeloablative irradiation (IRR) combined with infusion of donor specific alloantigen. In order to improve clinical applicability, we delayed induction with irradiation in this study. Left sided single LTx was performed in minipigs. Group 1 received non-myeloablative irradiation (7Gy thymus and 1.5Gy whole body IRR) before LTx and a perioperative donor specific splenocyte infusion (SpTx). Group 2 received perioperative SpTx but delayed IRR three days after LTx. Group 3 was exposed to delayed IRR without SpTx. Whereas 4 out of 7 animals from the non-delayed group never rejected their grafts and were electively sacrificed on postoperative day (POD) +500, all animals from group 2 rejected their grafts before POD 108. In group 3, 3 out of 8 animals developed long-term allograft acceptance. In all groups, donor leukocyte chimerism peaked up to 20% in peripheral blood one hour after reperfusion of the lung. Group 1 maintained prolonged chimerism beyond POD 7, whereas chimerism levels in groups 2 and 3 decreased continuously thereafter. Delayed irradiation has the potential to improve long-term graft survival, yet not as efficient as a perioperative conditioning protocol.

Novel mouse model of cardiopulmonary bypass

OBJECTIVES

Cardiopulmonary bypass (CPB) is an essential component of many cardiac interventions, and therefore, there is an increasing critical demand to minimize organ damage resulting from prolonged extracorporeal circulation. Our goal was to develop the first clinically relevant mouse model of CPB and to examine the course of extracorporeal circulation by closely monitoring haemodynamic and oxygenation parameters.

METHODS

Here, we report the optimization of device design, perfusion circuit and microsurgical techniques as well as validation of physiological functions during CPB in mice after circulatory arrest and reperfusion. Validation of the model required multiple blood gas analyses, and therefore, this initial report describes an acute model that is incompatible with survival due to the need of repetitive blood draws.

RESULTS

Biochemical and histopathological assessment of organ damage revealed only mild changes in the heart and lungs and signs of the beginning of acute organ failure in the liver and kidneys.

CONCLUSIONS

This new CPB mouse model will facilitate preclinical testing of therapeutic strategies in cardiovascular diseases and investigation of CPB in relation to different insults and pre-existing comorbidities. In combination with genetically modified mice, this model will be an important tool to dissect the molecular mechanisms involved in organ damage related to extracorporeal circulation.

Cardiopulmonary Bypass in a Mouse Model: A Novel Approach

As prolonged cardiopulmonary bypass becomes more essential during cardiac interventions, an increasing clinical demand arises for procedure optimization and for minimizing organ damage resulting from prolonged extracorporal circulation. The goal of this paper was to demonstrate a fully functional and clinically relevant model of cardiopulmonary bypass in a mouse. We report on the device design, perfusion circuit optimization, and microsurgical techniques. This model is an acute model, which is not compatible with survival due to the need for multiple blood drawings. Because of the range of tools available for mice (e.g., markers, knockouts, etc.), this model will facilitate investigation into the molecular mechanisms of organ damage and the effect of cardiopulmonary bypass in relation to other comorbidities.

Lung function early after lung transplantation is correlated with the frequency of regulatory T cells

PURPOSES

Outcomes following lung transplantation are limited by bronchiolitis obliterans syndrome (BOS). As the number of circulating regulatory T cells (Treg) is lower in lung recipients with BOS than in stable lung recipients, we hypothesized that Treg is also correlated with lung function in the early post-transplantation period.

METHODS

This prospective study included 18 consecutive patients whose lung function parameters were recorded 3 weeks and 3 months after transplantation, between February and July 2007. Peripheral blood mononuclear cells were stained with anti-CD3, -CD4, -CD8, -CD19, -CD25, -CD28, -CD45RA, -CD45RO, -CD69, -CD127, -CTLA4, and -Foxp3 antibodies and FACS assays were performed. In addition, intracellular cytokines were stained for FACS.

RESULTS

Treg-specific markers (Foxp3, CD127(lo), and CTLA4) in the CD25+ CD4+ population were correlated with both forced expiratory volume in 1 s and forced vital capacity. Th1-cytokine secretion was more dominant in CD4+ CD25+ T cells than in CD4+ CD25- T cells. In contrast, Th2 and Treg cytokine secretion was the dominant response in stable recipients.

CONCLUSIONS

The frequency of Treg cells was positively correlated with good lung function in the early period after lung transplantation.

Preconditioning therapy with lentiviral vector-programmed dendritic cells accelerates the homeostatic expansion of antigen-reactive human T cells in NOD.Rag1-/-.IL-2rγc-/- mice

Dendritic cell (DC)-based immunization is a potent strategy to direct prompt and durable immune responses against viral reactivations after transplantations. Here, we show that overnight lentiviral vector (LV) gene transfer into human monocytes co-expressing granulocyte-macrophage colony stimulating factor and interleukin (IL)-4 induced self-differentiated DCs (SMART-DCs) with stable DC immunophenotype over weeks in culture and secreted several inflammatory cytokines. SMART-DCs injected subcutaneously in immunodeficient NOD.Rag1(-/-).IL2rγ(-/-) (NRG) mice 1 day after LV transduction were stable for a month in vivo. "Conventional" DCs (cDCs) and SMART-DCs were compared with regard to their potency to accelerate the expansion, biodistribution, and antigenic stimulation of autologous human T cells. Peripheral blood cells obtained from human cytomegalovirus (hCMV)-reactive donors and full-length hCMV pp65 antigenic protein or peptides were used. DCs loaded with pp65 were administered subcutaneously into NRG mice as a preconditioning treatment a week prior to intravenous infusion with T cells. Optical imaging analyses demonstrated that in mice preconditioned with SMART-DC-pp65, T cells were directly recruited to the immunization site and subsequently spread to the spleen and other organs. A dramatic expansion of both human CD8(+) and CD4(+) T cells could be observed within a few days after infusion, and this was associated with consistent measurable CD8(+) effector memory T-cell responses against different pp65 epitopes. Thus, this mouse model demonstrates the proof-of-principle for SMART-DCs to accelerate expansion of human lymphocytes, resulting in poly-functional and antigen-specific immune responses against hCMV-pp65.

Time-based analysis of silver-stained proteins in acrylamide gels

Silver staining of proteins after PAGE often remains the method of choice in many laboratories. Nevertheless, it is known that quantification of protein levels is keenly restricted to a small range of protein concentrations leading to an over- or underestimation of protein amounts. To overcome this, a time-based analysis method was developed to avoid the saturation effect of the silver-staining reaction, thus resulting in an improved dynamic range of the gel image produced and therefore better quantification of proteins. Instead of the well-known end-point image analysis, gray intensities of time series images of a developing gel are determined and times until a threshold gray value is reached are calculated. These times are used to calculate a new grayscale image which can be analyzed using commercial image processing software.