Anja Thorenz

Unique human immune signature of Ebola virus disease in Guinea

Despite the magnitude of the Ebola virus disease (EVD) outbreak in West Africa, there is still a fundamental lack of knowledge about the pathophysiology of EVD. In particular, very little is known about human immune responses to Ebola virus. Here we evaluate the physiology of the human T cell immune response in EVD patients at the time of admission to the Ebola Treatment Center in Guinea, and longitudinally until discharge or death. Through the use of multiparametric flow cytometry established by the European Mobile Laboratory in the field, we identify an immune signature that is unique in EVD fatalities. Fatal EVD was characterized by a high percentage of CD4+ and CD8+ T cells expressing the inhibitory molecules CTLA-4 and PD-1, which correlated with elevated inflammatory markers and high virus load. Conversely, surviving individuals showed significantly lower expression of CTLA-4 and PD-1 as well as lower inflammation, despite comparable overall T cell activation. Concomitant with virus clearance, survivors mounted a robust Ebola-virus-specific T cell response. Our findings suggest that dysregulation of the T cell response is a key component of EVD pathophysiology.

Multiparametric Functional MRI: Non-Invasive Imaging of Inflammation and Edema Formation after Kidney Transplantation in Mice.

Background Kidney transplantation (ktx) in mice is used to learn about rejection and to develop new treatment strategies. Past studies have mainly been based on histological or molecular biological methods. Imaging techniques to monitor allograft pathology have rarely been used. Methods Here we investigated mice after isogenic and allogenic ktx over time with functional MRI with diffusion-weighted imaging (DWI) and mapping of T2-relaxation time (T2-mapping) to assess graft inflammation and edema formation. To characterize graft pathology, we used PAS-staining, counted CD3-positive T-lymphocytes, analyzed leukocytes by means flow cytometry. Results DWI revealed progressive restriction of diffusion of water molecules in allogenic kidney grafts. This was paralleled by enhanced infiltration of the kidney by inflammatory cells. Changes in tissue diffusion were not seen following isogenic ktx. T2-times in renal cortex were increased after both isogenic and allogenic transplantation, consistent with tissue edema due to ischemic injury following prolonged cold ischemia time of 60 minutes. Lack of T2 increase in the inner stripe of the inner medulla in allogenic kidney grafts matched loss of tubular autofluorescence and may result from rejection-driven reductions in tubular water content due to tubular dysfunction and renal functional impairment. Conclusions Functional MRI is a valuable non-invasive technique for monitoring inflammation, tissue edema and tubular function. It permits on to differentiate between acute rejection and ischemic renal injury in a mouse model of ktx.

Sodium Channel Nav1.3 Is Expressed by Polymorphonuclear Neutrophils during Mouse Heart and Kidney Ischemia In Vivo and Regulates Adhesion, Transmigration, and Chemotaxis of Human and Mouse Neutrophils In Vitro

Background: Voltage-gated sodium channels generate action potentials in excitable cells, but they have also been attributed noncanonical roles in nonexcitable cells. We hypothesize that voltage-gated sodium channels play a functional role during extravasation of neutrophils. Methods: Expression of voltage-gated sodium channels was analyzed by polymerase chain reaction. Distribution of Nav1.3 was determined by immunofluorescence and flow cytometry in mouse models of ischemic heart and kidney injury. Adhesion, transmigration, and chemotaxis of neutrophils to endothelial cells and collagen were investigated with voltage-gated sodium channel inhibitors and lidocaine in vitro. Sodium currents were examined with a whole cell patch clamp. Results: Mouse and human neutrophils express multiple voltage-gated sodium channels. Only Nav1.3 was detected in neutrophils recruited to ischemic mouse heart (25 ± 7%, n = 14) and kidney (19 ± 2%, n = 6) in vivo. Endothelial adhesion of mouse neutrophils was reduced by tetrodotoxin (56 ± 9%, unselective Nav-inhibitor), ICA121431 (53 ± 10%), and Pterinotoxin-2 (55 ± 9%; preferential inhibitors of Nav1.3, n = 10). Tetrodotoxin (56 ± 19%), ICA121431 (62 ± 22%), and Pterinotoxin-2 (59 ± 22%) reduced transmigration of human neutrophils through endothelial cells, and also prevented chemotactic migration (n = 60, 3 × 20 cells). Lidocaine reduced neutrophil adhesion to 60 ± 9% (n = 10) and transmigration to 54 ± 8% (n = 9). The effect of lidocaine was not increased by ICA121431 or Pterinotoxin-2. Conclusions: Nav1.3 is expressed in neutrophils in vivo; regulates attachment, transmigration, and chemotaxis in vitro; and may serve as a relevant target for antiinflammatory effects of lidocaine.

IL-17A blockade or deficiency does not affect progressive renal fibrosis following renal ischaemia reperfusion injury in mice

IL‐17A contributes to acute kidney injury and fibrosis. Therefore, we asked whether IL‐17A deficiency or treatment with a IL‐17A blocking antibody impacts severe renal ischaemia reperfusion injury (IRI) and the progression to chronic kidney disease (CKD).

Longitudinal evaluation of perfusion changes in acute and chronic renal allograft rejection using arterial spin labeling in translational mouse models

To examine the longitudinal changes of renal perfusion due to acute and chronic renal allograft rejection by using arterial spin labeling (ASL) MRI in translational mouse models of isogenic and allogenic kidney transplantation (ktx).

Ischemia Reperfusion Injury (IRI) causes Local Release of Free Heme which Aggravates Inflammation and Contributes to Delayed Graft Function

Ischemia reperfusion injury (IRI) is relevant in solid organ transplantation and contributes to delayed graft function (DGF). In this study, release of free heme after renal IRI and the consecutive inflammatory response were studied in mice. Methods Renal IRI was induced by 15, 35 and 45 min unilateral renal pedicle clamping in mice. Sham surgery served as control. Mice were sacrificed at 2 and 4 and 24 hours after IRI. Free heme was measured in the kidney and systemic complement activation was measured in blood samples. qPCR for pro-inflammatory cytokine expression, histology and immunohistochemistry for acute kidney injury were done. Results In correlation with increased duration of ischemia time the free heme generation in the tissue increased and enhanced local pro-inflammatory cytokine release (TNF-alpha, MCP-1, IL-6) was measured. AKI score and inflammatory cell infiltration into the tissue increased as well. Complement activation was higher in correlation with longer ischemia time Conclusion Free heme release in ischemic organs aggravates local inflammation. Strategies to reduce free heme production prior to solid organ transplantation would be promising therapeutic approaches to reduce the risk of DGF.

C5AR2 Deficiency Shows Enhanced Regeneration Capacity after Renal Ischemia Reperfusion Injury via AKT and FGF Dependent Mechanisms

Background Ischemia reperfusion injury (IRI) contributes to acute kidney injury (AKI) and to delayed graft function which can be up to 50% due to prolonged cold ischemia time kidney transplantation. A hallmark of IRI is activation of the comeplement system but so far, there is little known about the different roles of the two C5a receptors (C5aR1 versus C5aR2). In this study C5aR1 and C5aR2 deficient mice were investigated used in the renal IRI model and different pathological responses were by longitudinal monitoring. Methods Unilateral IRI of 45 min was done in C5aR1, C5aR2 -/- and wild type mice (WT). Renal morphology, inflammation, regeneration and renal fibrosis were investigated by immunohistochemistry and qPCR. To measure renal perfusion functional magnetic resonance imaging (MRI) was done at day 1, 7 and 21. Renal tissue was processed for high content antibody microarrays and differential total protein and phospho protein expression was analyzed. Based on the proteomics results AKT and p-AKT protein expression in the tissue was investigated by Western blotting. Results Extensive renal fibrosis was detected in WT mice within 3 weeks after IRI whereas C5aR deficienct mice showed partial protection. Especially, C5aR2 deficient mice showed enhanced tubular proliferation measured by Ki-67 expression and improved renal perfusion over time. Macrophage infiltration was attenuated in C5aR2 -/- mice and the transcript of the anti-inflammatory cytokine IL-10 was significantly up-regulated. Moreover, proteomics revealed significantly enhanced phosphorylation of the pro-angiogenic FGF1 in C5aR2-/- IRI kidneys at d1. In addition, total AKT protein and consecutively also phospho-AKT was significantly higher in C5aR2-/- compared to the other mouse strains. Conclusion C5aR2 deficient mice have enhanced p-FGF and p-AKT levels after IRI which might have contributed to improved regeneration of peritubular capillaries, tubular epithelial cells and better renal perfusion.

Enhanced activation of interleukin-10, heme oxygenase-1, and AKT in C5aR2-deficient mice is associated with protection from ischemia reperfusion injury–induced inflammation and fibrosis

Severe ischemia reperfusion injury (IRI) results in rapid complement activation, acute kidney injury and progressive renal fibrosis. Little is known about the roles of the C5aR1 and C5aR2 complement receptors in IRI. In this study C5aR1-/- and C5aR2-/- mice were compared to the wild type in a renal IRI model leading to renal fibrosis. C5a receptor expression, kidney morphology, inflammation, and fibrosis were measured in different mouse strains one, seven and 21 days after IRI. Renal perfusion was evaluated by functional magnetic resonance imaging. Protein abundance and phosphorylation were assessed with high content antibody microarrays and Western blotting. C5aR1 and C5aR2 were increased in damaged tubuli and even more in infiltrating leukocytes after IRI in kidneys of wild-type mice. C5aR1-/- and C5aR2-/- animals developed less IRI-induced inflammation and showed better renal perfusion than wild-type mice following IRI. C5aR2-/- mice, in particular, had enhanced tubular and capillary regeneration with less renal fibrosis. Anti-inflammatory IL-10 and the survival/growth kinase AKT levels were especially high in kidneys of C5aR2-/- mice following IRI. LPS caused bone marrow-derived macrophages from C5aR2-/- mice to release IL-10 and to express the stress response enzyme heme oxygenase-1. Thus, C5aR1 and C5aR2 have overlapping actions in which the kidneys of C5aR2-/- mice regenerate better than those in C5aR1-/- mice following IRI. This is mediated, at least in part, by differential production of IL-10, heme oxygenase-1 and AKT.

Gd-EOB-DTPA-enhanced MRI for quantitative assessment of liver organ damage after partial hepatic ischaemia reperfusion injury: correlation with histology and serum biomarkers of liver cell injury

ObjectiveTo evaluate Gd-EOB-DTPA-enhanced MRI for quantitative assessment of liver organ damage after hepatic ischaemia reperfusion injury (IRI) in mice.MethodsPartial hepatic IRI was induced in C57Bl/6 mice (n = 31) for 35, 45, 60 and 90 min. Gd-EOB-DTPA-enhanced MRI was performed 1 day after surgery using a 3D-FLASH sequence. A subgroup of n = 9 animals with 60 min IRI underwent follow-up with MRI and histology 7 days after IRI. The total liver volume was determined by manual segmentation of the entire liver. The volume of functional, contrast-enhanced liver parenchyma was quantified by a region growing algorithm (visual threshold) and an automated segmentation (Otsu’s method). The percentages of functional, contrast-enhanced and damaged non-enhanced parenchyma were calculated according to these volumes. MRI data was correlated with serum liver enzyme concentrations and histologically quantified organ damage using periodic acid–Schiff (PAS) staining.ResultsThe percentage of functional (contrasted) liver parenchyma decreased significantly with increasing ischaemia times (control, 94.4 ± 3.3%; 35 min IRI, 89.3 ± 4.1%; 45 min IRI, 87.9 ± 3.3%; 60 min IRI, 68 ± 10.5%, p < 0.001 vs. control; 90 min IRI, 55.9 ± 11.5%, p < 0.001 vs. control). The percentage of non-contrasted liver parenchyma correlated with histologically quantified liver organ damage (r = 0.637, p < 0.01) and serum liver enzyme elevations (AST r = 0.577, p < 0.01; ALT r = 0.536, p < 0.05). Follow-up MRI visualized recovery of functional liver parenchyma (71.5 ± 8.7% vs. 84 ± 2.1%, p < 0.05), consistent with less histological organ damage on day 7.ConclusionWe demonstrated the feasibility of Gd-EOB-DTPA-enhanced MRI for non-invasive quantification of damaged liver parenchyma following IRI in mice. This novel methodology may refine the characterization of liver disease and could have application in future studies targeting liver organ damage.Key Points• Prolonged ischaemia times in partial liver IRI increase liver organ damage.• Gd-EOB-DTPA-enhanced MRI at hepatobiliary phase identifies damaged liver volume after hepatic IRI.• Damaged liver parenchyma quantified with MRI correlates with histological liver damage.• Hepatobiliary phase Gd-EOB-DTPA-enhanced MRI enables non-invasive assessment of recovery from liver injury.

Renal ischemia reperfusion injury causes hypertension and renal perfusion impairment in the CD1 mice which promotes progressive renal fibrosis

Renal ischemia-reperfusion injury (IRI) is a severe complication of major surgery and a risk factor for increased morbidity and mortality. Here, we investigated mechanisms that might contribute to IRI-induced progression to chronic kidney disease (CKD). Acute kidney injury (AKI) was induced by unilateral IRI for 35 min in CD1 and C57BL/6 (B6) mice. Unilateral IRI was used to overcome early mortality. Renal morphology, NGAL upregulation, and neutrophil infiltration as well as peritubular capillary density were studied by immunohistochemistry. The composition of leukocyte infiltrates in the kidney after IRI was investigated by flow cytometry. Systemic blood pressure was measured with a tail cuff, and renal perfusion was quantified by functional magnetic resonance imaging (fMRI). Mesangial matrix expansion was assessed by silver staining. Following IRI, CD1 and B6 mice developed similar morphological signs of AKI and increases in NGAL expression, but neutrophil infiltration was greater in CD1 than B6 mice. IRI induced an increase in systemic blood pressure of 20 mmHg in CD1, but not in B6 mice; and CD1 mice also had a greater loss of renal perfusion and kidney volume than B6 mice ( P < 0.05). CD1 mice developed substantial interstitial fibrosis and decreased peritubular capillary (PTC) density by day 14 while B6 mice showed only mild renal scarring and almost normal PTC. Our results show that after IRI, CD1 mice develop more inflammation, hypertension, and later mesangial matrix expansion than B6 mice do. Subsequently, CD1 animals suffer from CKD due to impaired renal perfusion and pronounced permanent loss of peritubular capillaries.