Julia M. Huber

IL-9 Production by Regulatory T Cells Recruits Mast Cells That Are Essential for Regulatory T Cell-Induced Immune Suppression

Both mast cells (MCs) and regulatory T cells (Tregs) have gained attention as immunosuppressive cell populations. To investigate a possible interaction, we used the Th1- and Th17-dependent model of nephrotoxic serum nephritis (NTS), in which both MCs and Tregs have been shown to play a protective role. Transfer of wild-type (wt) Tregs into wt recipients almost completely prevents development of NTS and leads to a profound increase of MCs in the renal draining lymph nodes (LNs). By contrast, transfer of wt Tregs into animals deficient in MCs, which are characterized by an exaggerated susceptibility to NTS, no longer exhibited protective effects. Blocking the pleiotropic cytokine IL-9, known to be involved in MC recruitment and proliferation, by means of a mAb in mice receiving Tregs abrogated protection from NTS. Moreover, transfer of IL-9–deficient Tregs also failed to protect from NTS. In the absence of Treg-derived IL-9, MCs fail to accumulate in the LNs, despite the fact that IL-9 deficiency does not alter the general suppressive activity of Tregs. In summary, to our knowledge, we provide the first direct in vivo evidence that the nephroprotective, anti-inflammatory effects of Tregs critically depend on IL-9–mediated attraction of MCs into kidney-draining LNs.

Development of an Innovative 3D Cell Culture System to Study Tumour - Stroma Interactions in Non-Small Cell Lung Cancer Cells

Introduction We describe a novel 3D co-culture model using non-small cell lung cancer (NSCLC) cell lines in combination with lung fibroblasts. This model allows the investigation of tumour-stroma interactions and addresses the importance of having a more in vivo like cell culture model. Methods Automation-compatible multi-well hanging drop microtiter plates were used for the production of 3D mono- and co-cultures. In these hanging drops the two NSCLC cell lines A549 and Colo699 were cultivated either alone or co-cultured with lung fibroblasts. The viability of tumour spheroids was confirmed after five and ten days by using Annexin V/Propidium Iodide staining for flow-cytometry. Tumour fibroblast spheroid formation was characterized by scanning electron microscope (SEM), semi-thin sections, fluorescence microscope and immunohistochemistry (IHC). In addition to conventional histology, protein expression of E-Cadherin, vimentin, Ki67, fibronectin, cytokeratin 7 and α-smooth muscle actin (α-SMA) was investigated by IHC. Results Lower viability was observed in A549 monocultures compared to co-cultures, whereas Colo699 monocultures showed better viability compared to co-cultures. Ki67 expression varied significantly between mono- and co-cultures in both tumour cell lines. An increase of vimentin and decreased E-Cadherin expression could be detected during the course of the cultivation suggesting a transition to a more mesenchymal phenotype. Furthermore, the fibroblast cell line showed an expression of α-SMA only in co-culture with the cancer cell line A549, thereby indicating a mesenchymal to mesenchymal shift to an even more myofibroblast phenotype. Conclusion We demonstrate that our method is a promising tool for the generation of tumour spheroid co-cultures. Furthermore, these spheroids allow the investigation of tumour-stroma interactions and a better reflection of in vivo conditions of cancer cells in their microenvironment. Our method holds potential to contribute to the development of anti-cancer agents and support the search for biomarkers.

The Liver-Selective Thyromimetic T-0681 Influences Reverse Cholesterol Transport and Atherosclerosis Development in Mice

Background Liver-selective thyromimetics have been reported to efficiently reduce plasma cholesterol through the hepatic induction of both, the low-density lipoprotein receptor (LDLr) and the high-density lipoprotein (HDL) receptor; the scavenger receptor class B type I (SR-BI). Here, we investigated the effect of the thyromimetic T-0681 on reverse cholesterol transport (RCT) and atherosclerosis, and studied the underlying mechanisms using different mouse models, including mice lacking LDLr, SR-BI, and apoE, as well as CETP transgenic mice. Methodology/Principal Findings T-0681 treatment promoted bile acid production and biliary sterol secretion consistently in the majority of the studied mouse models, which was associated with a marked reduction of plasma cholesterol. Using an assay of macrophage RCT in mice, we found T-0681 to significantly increase fecal excretion of macrophage-derived neutral and acidic sterols. No positive effect on RCT was found in CETP transgenic mice, most likely due to the observed decrease in plasma CETP mass. Studies in SR-BI KO and LDLr KO mice suggested hepatic LDLr to be necessary for the action of T-0681 on lipid metabolism, as the compound did not have any influence on plasma cholesterol levels in mice lacking this receptor. Finally, prolonged treatment with T-0681 reduced the development of atherosclerosis by 60% in apoE KOs on Western type diet. In contrast, at an earlier time-point T-0681 slightly increased small fatty streak lesions, in part due to an impaired macrophage cholesterol efflux capacity, when compared to controls. Conclusions/Significance The present results show that liver-selective thyromimetics can promote RCT and that such compounds may protect from atherosclerosis partly through induction of bile acid metabolism and biliary sterol secretion. On-going clinical trials will show whether selective thyromimetics do prevent atherosclerosis also in humans.

The proteasome inhibitor Bortezomib aggravates renal ischemia-reperfusion injury

Bortezomib is a well-established treatment option for patients with multiple myeloma (MM). It is a selective and reversible inhibitor of the proteasome that is responsible for the degradation of many regulatory proteins that are involved in apoptosis, cell-cycle regulation, or transcription. Because patients with MM are prone to develop acute renal failure, we evaluated the influence of bortezomib on renal ischemia-reperfusion injury (IRI). Mice were subjected to renal IRI by having the renal pedicles clamped for 30 min followed by reperfusion for 3, 24, and 48 h. Mice were either pretreated with 0.5 mg/kg body wt bortezomib or vehicle intravenously 12 h before induction of IRI. Serum creatinine and tubular necrosis were significantly increased in bortezomib compared with vehicle-treated mice. The inflammatory response was found to be significantly decreased in bortezomib-treated mice as reflected by a decreased infiltration of CD4(+) T cells and a significantly decreased Th1 cytokine expression in the kidneys. In contrast, apoptosis was significantly increased in kidneys of bortezomib-treated mice compared with vehicle-treated controls. Increased numbers of TUNEL-positive cells/mm(2) and increased mRNA expression of proapoptotic factors were detected in kidneys of bortezomib-treated mice. Of note, p21, a cell senescence marker, was also significantly increased in kidneys of bortezomib-treated mice. In summary, we provide evidence that bortezomib worsens the outcome of renal IRI by leading to increased apoptosis of tubular cells despite decreased infiltrating T cells and proinflammatory mediators.

Reduced plasma high-density lipoprotein cholesterol in hyperthyroid mice coincides with decreased hepatic adenosine 5 '-triphosphate-binding cassette transporter 1 expression

The aim of the study was to investigate the influence of severe hyperthyroidism on plasma high-density lipoprotein cholesterol (HDL-C). Recently, it was shown in mice that increasing doses of T(3) up-regulate hepatic expression of scavenger receptor class B, type I, resulting in increased clearance of plasma HDL-C. Here, we show that severe hyperthyroidism in mice did not affect hepatic expression of scavenger receptor class B, type I, but reduced hepatic expression of ATP-binding cassette transporter 1, accompanied by a 40% reduction of HDL-C. The sterol content of bile, liver, and feces was markedly increased, accompanied by up-regulation of hepatic cholesterol 7alpha-hydroxylase, and ATP-binding cassette transporter 5, which is known to promote biliary sterol secretion upon dimerization with ATP-binding cassette transporter 8. Both control and hyperthyroid mice exerted identical plasma clearance of iv injected [(3)H]HDL-C, supporting the view that severe hyperthyroidism does not affect HDL-C clearance but, rather, its formation via hepatic ATP-binding cassette transporter 1.

Lipocalin-2 Expressed in Innate Immune Cells Is an Endogenous Inhibitor of Inflammation in Murine Nephrotoxic Serum Nephritis

Lipocalin-2 (Lcn-2) is involved in divergent processes such as acute kidney injury or bacterial host defence. Our study was designed to evaluate the functional role of Lcn-2 in nephrotoxic serum nephritis (NTS). Since Lcn-2 is expressed in tubular epithelial cells as well as in cells of innate immunity such as macrophages and polymorphonuclear neutrophils (PMN), we induced NTS in wild-type (WT), Lcn-2 knock-out (KO) mice and WT/Lcn-2 KO chimeras. Mice lacking Lcn-2 exhibited more glomerular damage with increased proteinuria and interstitial leukocyte accumulation compared to WT mice. Chimeras able to express Lcn-2 in macrophages and PMN but not in epithelial cells were found to develop NTS comparable to wild-type controls. In contrast, chimeras expressing Lcn-2 in tubular epithelial cells with no expression in innate immune cells developed increased NTS due to decreased concerted apoptosis but increased necrosis and formation of damage-associated molecular patterns (DAMPs) such as high-mobility group box 1 (HMGB-1) in the kidney. In vivo blockade of HMGB-1, a toll-like receptor (TLR)-2 agonist, significantly reduced inflammation and NTS in Lcn-2 knock-out mice. In parallel, TLR-2 signalling was found to drive Lcn-2 transcription in vitro. Taken together, Lcn-2 expressed in innate immune cells is protective in NTS by inducing concerted apoptosis and inhibiting the formation of HMGB-1 thereby limiting cytokine production via TLR-2 signalling. In parallel, TLR-2 dependent transcription of Lcn-2 is an endogenous inhibitor of inflammation in NTS.

Tim3 Is Upregulated and Protective in Nephrotoxic Serum Nephritis

T cell immunoglobulin and mucin protein-3 (Tim3) is mainly expressed on the cell surface of T-helper lymphocytes (T(H)) that negatively regulates T(H)-type 1 (T(H)-1) responses. Because blockade of Tim3 aggravates disease activity in T(H)-1-dependent diseases, we investigated whether Tim3 is involved in the pathogenesis of the T(H)-1-dependent nephrotoxic nephritis (NTS). We first evaluated Tim3 expression in mice after induction of nephrotoxic serum nephritis (NTS) and then studied the effects of anti-Tim3 treatment toward the course of NTS for up to seven days. Whereas Tim3 expression was undetectable in control mice, we found significantly increased Tim3 expression in kidneys, but not in draining lymph nodes, at one, four, and eight weeks after induction of NTS. Tim3-expressing cells that infiltrated kidneys of mice subjected to NTS turned out to be CD4(+) T cells rather than CD8(+) cytotoxic T cells and dendritic cells. Administration of a blocking anti-Tim3 antibody aggravated nephritis as shown by significantly increased albuminuria, respective histological changes, and increased expression of the kidney injury molecule lipocalin-2. In parallel, an increase of infiltrating T cells, macrophages, and macrophage pro-inflammatory cytokine formation as well as increased proliferation and apoptosis in kidneys of anti-Tim3-treated mice was detected. Together, we provide the first evidence that Tim3 is up-regulated in kidneys in NTS and that Tim3 exerts protective roles in the course of disease.

Expression of granzyme A in human polymorphonuclear neutrophils

Polymorphonuclear neutrophils (PMNs) are the first line of defence against invading pathogens. They contain a multitude of antimicrobial and potentially cytotoxic substances packed in granules and secretory vesicles. Here, we show that granzyme A (GzmA) is constitutively expressed in human PMNs, but not in the promyelocytic cell line HL‐60, by performing flow cytometry, western blot, enzyme‐linked immunosorbent assay and quantitative polymerase chain reaction. To further track the intracellular localization of GzmA, we performed subcellular fractionation and found GzmA to be present in peroxidase‐negative granules. Finally, stimulation with opsonized Escherichia coli or the bioincompatible haemodialysis membrane cuprophane led to up‐regulation of GzmA expression at the transcriptional level as well as at the translational level. In conclusion, we provide clear evidence that GzmA is constitutively expressed in human PMNs and can be up‐regulated upon stimulation. These findings may also indicate a role for GzmA in PMNs in defence against invading pathogens.

Development of a 3D angiogenesis model to study tumour – endothelial cell interactions and the effects of anti-angiogenic drugs

The tumour microenvironment and tumour angiogenesis play a critical role in the development and therapy of many cancers, but in vitro models reflecting these circumstances are rare. In this study, we describe the development of a novel tri-culture model, using non-small cell lung cancer (NSCLC) cell lines (A549 and Colo699) in combination with a fibroblast cell line (SV 80) and two different endothelial cell lines in a hanging drop technology. Endothelial cells aggregated either in small colonies in Colo699 containing microtissues or in tube like structures mainly in the stromal compartment of microtissues containing A549. An up-regulation of hypoxia and vimentin, ASMA and a downregulation of E-cadherin were observed in co- and tri-cultures compared to monocultures. Furthermore, a morphological alteration of A549 tumour cells resembling “signet ring cells” was observed in tri-cultures. The secretion of proangiogenic growth factors like vascular endothelial growth factor (VEGF) was measured in supernatants. Inhibition of these proangiogenic factors by using antiangiogenic drugs (bevacizumab and nindetanib) led to a significant decrease in migration of endothelial cells into microtissues. We demonstrate that our method is a promising tool for the generation of multicellular tumour microtissues and reflects in vivo conditions closer than 2D cell culture.

Infiltration of lymphocyte subpopulations into cancer microtissues as a tool for the exploration of immunomodulatory agents and biomarkers

INTRODUCTION The interaction between the immune system and malignant diseases is a proven key target for cancer therapy. We describe an innovative 3D cell culture system comprising both immune and cancer cells to evaluate their interaction and immune cell infiltration to provide an innovative in vitro screening of immunomodulatory agents and biomarkers. METHODS 3D tumor microtissues were cultivated using a hanging drops system. Human non-small-cell lung cancer cell lines were incubated for 7 days to form microtissues. On day 5, peripheral blood mononuclear cells (PBMC) were added with or without interleukin-2 (IL-2) for 24 or 48h. Viability of cancer cells and the infiltrating PBMC subpopulations were investigated by flow cytometry. Aggregation of tumor cells and PBMC and the infiltration of the PBMC into the tumor microtissues were analyzed by immunohistochemistry. Quantification of infiltration was measured by applying the TissueFAXS system. RESULTS Immunohistochemistry revealed PBMC infiltration in all cell lines which increased under IL-2 stimulation. Analysis of infiltrating populations showed both lymphocyte subpopulations and monocytes within the tumor microtissues. In all three co-cultures, CD3+CD8+ and CD3+CD8+CD45R0+CD28+ lymphocytes were increased with IL-2, whereas CD3+CD8+CD45R0-CD28+ PBMCs were decreased with and without IL-2 stimulation. CONCLUSION In summary, we present a novel cell culture system to study the interaction between cancer cells and immune cells in 3-dimensional microtissues. In addition, we report for the first time an in vitro infiltration assay based on 3D microtissues. This model has the potential to provide a tool for ex-vivo drug testing and biomarker screening of immunomodulatory agents.