Katrin Splith

Increased plasma levels of microparticles expressing CD39 and CD133 in acute liver injury

Background We have previously demonstrated that CD133 and CD39 are expressed by hematopoietic stem cells (HSC), which are mobilized after liver injury and target sites of injury, limit vascular inflammation, and boost hepatic regeneration. Plasma microparticles (MP) expressing CD39 can block endothelial activation. Here, we tested whether CD133+ MP might be shed in a CD39-dependent manner in a model of liver injury and could potentially serve as biomarkers of liver failure in the clinic. Methods Wild-type and Cd39-null mice were subjected to acetaminophen-induced liver injury. Mice were sacrificed and plasma MP were isolated by ultracentrifugation. HSC and CD133+ MP levels were analyzed by fluorescence-activated cell sorting. Patients were enrolled with acute (n=5) and acute on chronic (n=5) liver injury with matched controls (n=7). Blood was collected at admission and plasma CD133+ and CD39+ MP subsets were analyzed by fluorescence-activated cell sorting. Results HSC and CD133+ MP levels were significantly increased only in the plasma of wild-type mice with acetaminophen hepatotoxicity (P<0.05). No increases in CD133+ MP were noted in Cd39-null mice. Plasma MP increases were observed in patients with liver injury. These MP were characterized by significantly higher levels of CD39 (P<0.05). Conclusions HSC and plasma CD133+ MP levels increase in a CD39-dependent manner during experimental acute liver injury. Increased levels of CD39+ MP are differentially noted in patients with liver injury. Further research is needed to determine whether MP fluxes are secondary to pathophysiologic insults to the liver or might reflect compensatory responses.

Age-Dependent Metabolic and Immunosuppressive Effects of Tacrolimus.

Immunosuppression in elderly recipients has been underappreciated in clinical trials. Here, we assessed age‐specific effects of the calcineurin inhibitor tacrolimus (TAC) in a murine transplant model and assessed its clinical relevance on human T cells. Old recipient mice exhibited prolonged skin graft survival compared with young animals after TAC administration. More important, half of the TAC dose was sufficient in old mice to achieve comparable systemic trough levels. TAC administration was able to reduce proinflammatory interferon‐γ cytokine production and promote interleukin‐10 production in old CD4+ T cells. In addition, TAC administration decreased interleukin‐2 secretion in old CD4+ T cells more effectively while inhibiting the proliferation of CD4+ T cells in old mice. Both TAC‐treated murine and human CD4+ T cells demonstrated an age‐specific suppression of intracellular calcineurin levels and Ca2+ influx, two critical pathways in T cell activation. Of note, depletion of CD8+ T cells did not alter allograft survival outcome in old TAC‐treated mice, suggesting that TAC age‐specific effects were mainly CD4+ T cell mediated. Collectively, our study demonstrates age‐specific immunosuppressive capacities of TAC that are CD4+ T cell mediated. The suppression of calcineurin levels and Ca2+ influx in both old murine and human T cells emphasizes the clinical relevance of age‐specific effects when using TAC.

Antibody-Mediated Rejection of Arterialised Venous Allografts Is Inhibited by Immunosuppression in Rats

Objectives and Design We determined in a rat model (1) the presence and dynamics of alloantibodies recognizing MHC complexes on quiescent Brown-Norway (BN) splenic cells in the sera of Lewis (LEW) recipients of Brown-Norway iliolumbar vein grafts under tacrolimus immunosuppression; and (2) the presence of immunoglobulins in the wall of acute rejected vein allografts. Materials and Methods Flow cytometry was used for the analysis of day 0, 14 and 30 sera obtained from Lewis recipients of isogeneic iliolumbar vein grafts (group A) or Brown-Norway grafts (group B, C) for the presence of donor specific anti-MHC class I and II antibodies. Tacrolimus 0.2 mg/kg daily was administered from day 1 to day 30 (group C). Histology was performed on day 30. Results Sera obtained preoperatively and on day 30 were compared in all groups. The statistically significant decrease of anti MHC class I and II antibody binding was observed only in allogenic non-immunosuppressed group B (splenocytes: MHC class I - day 0 (93%±7% ) vs day 30 (66%±7%), p = 0.02, MHC class II - day 0 (105%±3% ) vs day 30 (83%±5%), p = 0.003; B-cells: MHC class I - day 0 (83%±5%) vs day 30 (55%±6%), p = 0.003, MHC class II - day 0 (101%±1%) vs day 30 (79%±6%), p = 0.006; T-cells: MHC class I - day 0 (71%±7%) vs day 30 (49%±5%), p = 0.04). No free clusters of immunoglobulin G deposition were detected in any experimental group. Conclusion Arterialized venous allografts induce strong donor-specific anti-MHC class I and anti-MHC class II antibody production with subsequent immune-mediated destruction of these allografts with no evidence of immunoglobulin G deposition. Low-dose tacrolimus suppress the donor-specific antibody production.

Immunosuppressive protocol with delayed use of low-dose tacrolimus after aortic transplantation suppresses donor-specific anti-MHC class I and class II antibody production in rats.

BACKGROUND Arterial allografts are used as vascular conduits in the treatment of prosthetic graft infection. Immunosuppression decreases their rupture risk rate. However, immunosuppression can be unprofitable in florid infection. Previously, we confirmed inhibition of cell-mediated destruction of rat aortic grafts by delayed use of tacrolimus. In this work, we studied the influence of this protocol on the antibody-mediated rejection. MATERIAL AND METHODS Flow cytometry was used for the retrospective analysis of day 0, 14, and 30 sera obtained from Lewis rat recipients of isogeneic fresh infrarenal aortic grafts (group A) or Brown-Norway rat aortic grafts (group B,C,D) for the presence of donor-specific anti-MHC class I and II antibodies. Tacrolimus in daily dose of 0.2 mg/kg was administered from day 1 to day 30 (group C) or from day 7 to day 30 (group D). RESULTS Inhibition of fluorescence-labeled anti-BN MHC class I and MHC class II antibodies binding to BN-splenocytes was observed only by day 14 and day 30 sera of allogeneic non-immunosuppressed Lewis rats (group B). The day 30 sera significantly decreased anti-MHC I (42±3%) and anti-MHC II antibody binding (56±3%) compared to day 0 (76±9%, p=0.005 and 79±5%, p=0.003, respectively). Deposition of immunoglobulins G into the tunica media was observed only in non-immunosuppressed aortic allografts on day 30. CONCLUSIONS Fresh aortic allografts induce donor-specific anti-MHC class I and anti-MHC class II antibody production. Delayed administration of tacrolimus completely suppressed antibody production and antibody-mediated destruction of aortic allografts.

Biological characterization of novel nitroimidazole-peptide conjugates in vitro and in vivo

Recently, we reported on the design of a multimodal peptide conjugate useful as delivery platform for targeting hypoxic cells. A nitroimidazole (2‐(2‐nitroimidazol‐1‐yl)acetic acid, NIA) moiety, which is selectively entrapped in hypoxic cells, was coupled to a cell‐penetrating peptide serving as the transporter. Furthermore, attachment of a bifunctional linker allowed the introduction of a diagnostic or therapeutic radiometal. However, although selective tumor accumulation could be detected in vivo, a fast renal clearance of the compound was observed. The present study aims to improve the system by using the more proteolytically stable all‐d version of the peptide carrier (DsC18), by attaching two NIA moieties instead of one (DsC18(NIA)2) to enhance the tumor uptake, and by incorporating the bifunctional chelator NODAGA instead of DOTA (NODAGA‐DsC18(NIA)2) to optimize labeling chemistry. First, we characterized in vitro the novel all‐d peptide compared with its parent l‐version. Then, in order to investigate and compare the pharmacological profiles of the peptides, these were radiolabeled with 64CuII and 68GaIII, and the biodistribution and kinetics were evaluated in vivo. Our results show the versatility of the d‐peptide as cell‐penetrating peptide and transporter. However, attaching two NIA groups modified the system in such a way that no selective tumor uptake could be observed compared with the peptide without NIA moieties. Still, this work highlights new pharmacokinetic data on the biodistribution of such compounds in vivo. Copyright

Ascites’ neutrophil function is significantly impaired in patients with decompensated cirrhosis but can be restored by autologous plasma incubation

Systemic immune cell dysfunction is a typical feature of liver diseases and increases the risk of bacterial infection, especially spontaneous bacterial peritonitis. We evaluated functional properties of neutrophil granulocytes in blood and ascites of patients both with and without decompensated cirrhosis. We collected blood and ascites samples from 63 patients with cirrhosis and eight without cirrhosis. Phagocytosis activity (PA) and oxidative burst activity (OBA) were evaluated after ex vivo stimulation with E. coli, while fluorescence signals were measured by flow cytometry. Ascites’ neutrophil function tests were repeated after incubation with autologous plasma. Ascites’ neutrophils showed an impaired PA and OBA (median blood PA 98.1% (86.8–99.8) vs. ascites’ PA 50.5% (0.4–97.3), p < 0.0001; median blood OBA 98.7% (27.5–100) vs. ascites’ OBA 27.5% (0.3–96.7), p < 0.0001). Patients with non-cirrhotic ascites showed higher PA but equally suppressed OBA. Ascites’ neutrophil function could be partially restored after incubation with autologous plasma (median increase PA: 22.5% (−49.7 – +93.2), p = 0.002; OBA: 22.8% (−10.4 – +48.8), p = 0.002). Ascites’ neutrophils of patients with cirrhosis are functionally impaired, but could be partially restored after incubation with plasma. Further investigations are needed to identify the factors in ascites that are associated with neutrophils’ function.

The nanomolar sensing of nicotinamide adenine dinucleotide in human plasma using a cycling assay in albumin modified simulated body fluids

Nicotinamide adenine dinucleotide (NAD), a prominent member of the pyridine nucleotide family, plays a pivotal role in cell-oxidation protection, DNA repair, cell signalling and central metabolic pathways, such as beta oxidation, glycolysis and the citric acid cycle. In particular, extracellular NAD+ has recently been demonstrated to moderate pathogenesis of multiple systemic diseases as well as aging. Herein we present an assaying method, that serves to quantify extracellular NAD+ in human heparinised plasma and exhibits a sensitivity ranging from the low micromolar into the low nanomolar domain. The assay achieves the quantification of extracellular NAD+ by means of a two-step enzymatic cycling reaction, based on alcohol dehydrogenase. An albumin modified revised simulated body fluid was employed as standard matrix in order to optimise enzymatic activity and enhance the linear behaviour and sensitivity of the method. In addition, we evaluated assay linearity, reproducibility and confirmed long-term storage stability of extracellular NAD+ in frozen human heparinised plasma. In summary, our findings pose a novel standardised method suitable for high throughput screenings of extracellular NAD+ levels in human heparinised plasma, paving the way for new clinical discovery studies.

Mononuclear-cell-derived microparticles attenuate endothelial inflammation by transfer of miR-142-3p in a CD39 dependent manner

Plasma microparticles (MP) bear functional active ectonucleotidases of the CD39 family with implications in vascular inflammation. MP appear to be able to fuse with cells and transfer genetic information. Here, we tested whether levels of different immunomodulatory microRNAs (miRs) in plasma MP are modulated by CD39 after experimental hepatectomy. We further investigated whether horizontal transfer of miR-142-3p between mononuclear (MNC) and endothelial cells via MP is regulated by purinergic signaling. Partial hepatectomy was performed in C57BL/6 wild type and Cd39 null mice. MP were collected via ultracentrifugation. MNC were stimulated with nucleotides and nucleosides, in vitro, and tested for miR-142-3p levels. Fusion of MNC-derived MP and endothelial cells with subsequent transfer of miR-142-3p was imaged by flow cytometry and confocal microscopy. Endothelial inflammation and apoptosis were quantified after transfection with miR-142-3p. Significantly lower miR-142-3p levels were observed in plasma MP of Cd39 null mice after partial hepatectomy, when compared to C57BL/6 wild types (p < 0.05). In contrast to extracellular nucleotides, anti-inflammatory adenosine significantly increased miR-142-3p levels in MNC-derived MP, in vitro (p < 0.05). MNC-derived MP are able to transfer miR-142-3p to endothelial cells by fusion. Transfection of endothelial cells with miR-142-3p decreased TNF-α levels (p < 0.05) and endothelial apoptosis (p < 0.05). MiR-142-3p levels in MNC-derived MP are modulated by nucleoside signaling and might reflect compensatory responses in vascular inflammation. Our data suggest the transfer of genetic information via shed MP as a putative mechanism of intercellular communication—with implications in organ regeneration.

Angiogenic miRNAs, the angiopoietin axis and related TIE2-expressing monocytes affect outcomes in cholangiocarcinoma

Background Tumour angiogenesis is modulated on both an epigenetic and protein level and has potential implications for immune cell responses. However, the importance of related angiogenic biomarkers in cholangiocarcinoma (CCA) is unknown. This study assessed human CCA samples for the expression of angiogenesis-associated microRNAs, angiopoietins (Angs) and monocytes expressing the Ang-receptor, TIE2, with regards to prognostic significance after liver resection. Methods Angiogenic miRNAs were analysed in frozen samples of intrahepatic CCA (iCC; n = 43) and hilar CCA (HC; n = 45). Ang-1 and Ang-2, as well as TIE2-expressing monocytes (TEMs), were detected in paraffin-embedded iCC sections (n = 88). MiRNA expression and the abundance of TEMs and Angs were correlated with clinicopathological characteristics and survival. Results MiR-126 was downregulated in 76.7% of all CCA samples, with high relative expression associated with smaller tumours and reduced lymph node metastasis. High Ang-1 expression was associated with less lymphangiosis carcinomatosa and better histological grading (all p < 0.05). The absence of TEMs in iCC correlated with elevated CA19-9 levels. High relative miR-126 and low miR-128 levels were associated with improved survival in iCC and HC, respectively (all p < 0.05). High miR-126, low miR-128 and TEMs were independent prognostic factors for recurrence-free and overall survival (all p < 0.05). Conclusions These results suggest that angiogenic miRNAs, Angs and TEMs are of prognostic value in CCA. In addition to the possible functional links between angiogenic miRNA expression profiles, Angs and immune-cell responses by TEMs, these data have clinical implications as novel diagnostic tools.

The value of microparticles in detecting acute rejection episodes after liver transplantation

Abstract Context: Non-invasive markers for diagnosis of acute rejection (AR) following liver transplantation have not been developed, yet. Objective: We analyzed the correlation of plasma microparticle levels (MP) with AR. Materials and Methods: MP (CD4, CD8, CD25, CD31, MHC) of 11 AR patients and 11 controls were analyzed within the first week after transplantation. Results: CD4, CD8 and CD31 positive MP were higher in the AR, whereas overall MP count, CD25 and MHCI positive MP proportions did not differ between both groups. Discussion and Conclusion: MP dynamics within the first period of transplantation could help to clarify on-going mechanisms of immunomodulation.