Alemtuzumab preconditioning with tacrolimus monotherapy - The impact of serial monitoring for donor-specific antibody

BACKGROUND. Antibody preconditioning with tacrolimus monotherapy has allowed many renal allograft recipients to be maintained on spaced weaning. METHODS. Of 279 renal allograft recipients transplanted between March 2003 and December 2004, 222 (80%) had spaced weaning (i.e., reduction of tacrolimus monotherapy dosing to every other day, three times a week, twice a week, or once a week) attempted. Routine monitoring for donor-specific antibody (DSA) was begun in September 2004. Mean follow-up is 34±6.5 months after transplantation and 26±8.1 months after the initiation of spaced weaning. RESULTS. One hundred and twenty-two (44%) patients remained on spaced weaning. One- and 2-year actual patient/graft survival was 99%/99%, and 97%/96%. Fifty-six (20%) patients experienced acute rejection after initiation of spaced weaning. One- and 2-year actual patient/graft survival was 100%/98%, and 94%/78%. Forty-two (15%) patients with stable renal function had spaced weaning stopped because of the development of DSA, which disappeared in 17 (40%). One- and 2-year actual patient and graft survival was 100% and 100%. CONCLUSION. Adult renal transplant recipients who are able to be maintained on spaced weaning have excellent outcomes. Patients with stable renal function who have reversal of weaning because of the development of DSA also have excellent outcomes. Routine monitoring for DSA may allow patients to avoid late rejection after spaced weaning. © 2008 Lippincott Williams & Wilkins, Inc

Identification of the cathelicidin peptide LL-37 as agonist for the type I insulin-like growth factor receptor

The human cathelicidin antimicrobial protein-18 and its C terminal peptide, LL-37, displays broad antimicrobial activity that is mediated through direct contact with the microbial cell membrane. In addition, recent studies reveal that LL-37 is involved in diverse biological processes such as immunomodulation, apoptosis, angiogenesis and wound healing. An intriguing role for LL-37 in carcinogenesis is also beginning to emerge and the aim of this paper was to explore if and how LL-37 contributes to the signaling involved in tumor development. To this end, we investigated the putative interaction between LL-37 and growth factor receptors known to be involved in tumor growth and progression. Among several receptors tested, LL-37 bound with the highest affinity to insulin-like growth factor 1 receptor (IGF-1R), a receptor that is strongly linked to malignant cellular transformation. Furthermore, this interaction resulted in a dose-dependent phosphorylation and ubiquitination of IGF-1R, with downstream signaling confined to the mitogen-activated protein kinase/extracellular signal-regulated kinase (ERK)-pathway but not affecting phosphatidylinositol 3 kinase/Akt signaling. We found that signaling induced by LL-37 was dependent on the recruitment of β-arrestin to the fully functional IGF-1R and by using mutant receptors we demonstrated that LL-37 signaling is dependent on β-arrestin-1 binding to the C-terminus of IGF-1R. When analyzing the biological consequences of increased ERK activation induced by LL-37, we found that it resulted in enhanced migration and invasion of malignant cells in an IGF-1R/β-arrestin manner, but did not affect cell proliferation. These results indicate that LL-37 may act as a partial agonist for IGF-1R, with subsequent intra-cellular signaling activation driven by the binding of β-arrestin-1 to the IGF-1R. Functional experiments show that LL-37-dependent activation of the IGF-1R signaling resulted in increased migratory and invasive potential of malignant cells

Proteasome inhibitor-based therapy for antibody-mediated rejection

The development of donor-specific anti-human leukocyte antigen antibodies (DSAs) following renal transplantation significantly reduces long-term renal graft function and survival. The traditional therapies for antibody-mediated rejection (AMR) have provided inconsistent results and transient effects that may be due to a failure to deplete mature antibody-producing plasma cells. Proteasome inhibition (PI) is a novel AMR therapy that deletes plasma cells. Initial reports of PI-based AMR treatment in refractory rejection demonstrated the ability of bortezomib to deplete plasma cells producing DSA, reduce DSA levels, provide histological improvement or resolution, and improve renal allograft function. These results have subsequently been confirmed in a multicenter collaborative study. PI has also been shown to provide effective primary AMR therapy in case reports. Recent studies have demonstrated that PI therapy results in differential responses in early and late post-transplant AMR. Additional randomized studies are evaluating the role of PI in transplant induction, acute AMR, and chronic rejection in renal transplantation. An important theoretical advantage of PI-based regimens is derived from several potential strategies for achievement of synergy

Differentiated transplant derived airway epithelial cell cytokine secretion is not regulated by cyclosporine

<p>Abstract</p> <p>Background</p> <p>While lung transplantation is an increasingly utilized therapy for advanced lung diseases, chronic rejection in the form of Bronchiolitis Obliterans Syndrome (BOS) continues to result in significant allograft dysfunction and patient mortality. Despite correlation of clinical events with eventual development of BOS, the causative pathophysiology remains unknown. Airway epithelial cells within the region of inflammation and fibrosis associated with BOS may have a participatory role.</p> <p>Methods</p> <p>Transplant derived airway epithelial cells differentiated in air liquid interface culture were treated with IL-1β and/or cyclosporine, after which secretion of cytokines and growth factor and gene expression for markers of epithelial to mesenchymal transition were analyzed.</p> <p>Results</p> <p>Secretion of IL-6, IL-8, and TNF-α, but not TGF-β1, was increased by IL-1β stimulation. In contrast to previous studies using epithelial cells grown in submersion culture, treatment of differentiated cells in ALI culture with cyclosporine did not elicit cytokine or growth factor secretion, and did not alter IL-6, IL-8, or TNF-α production in response to IL-1β treatment. Neither IL-1β nor cyclosporine elicited expression of markers of the epithelial to mesenchymal transition E-cadherin, EDN-fibronectin, and α-smooth muscle actin.</p> <p>Conclusion</p> <p>Transplant derived differentiated airway epithelial cell IL-6, IL-8, and TNF-α secretion is not regulated by cyclosporine <it>in vitro</it>; these cells thus may participate in local inflammatory responses in the setting of immunosuppression. Further, treatment with IL-1β did not elicit gene expression of markers of epithelial to mesenchymal transition. These data present a model of differentiated airway epithelial cells that may be useful in understanding epithelial participation in airway inflammation and allograft rejection in lung transplantation.</p

Cellular glycosylation affects Herceptin binding and sensitivity of breast cancer cells to doxorubicin and growth factors

Alterations in protein glycosylation are a key feature of oncogenesis and have been shown to affect cancer cell behaviour perturbing cell adhesion, favouring cell migration and metastasis. This study investigated the effect of N-linked glycosylation on the binding of Herceptin to HER2 protein in breast cancer and on the sensitivity of cancer cells to the chemotherapeutic agent doxorubicin (DXR) and growth factors (EGF and IGF-1). The interaction between Herceptin and recombinant HER2 protein and cancer cell surfaces (on-rate/off-rate) was assessed using a quartz crystal microbalance biosensor revealing an increase in the accessibility of HER2 to Herceptin following deglycosylation of cell membrane proteins (deglycosylated cells Bmax: 6.83 Hz; glycosylated cells Bmax: 7.35 Hz). The sensitivity of cells to DXR and to growth factors was evaluated using an MTT assay. Maintenance of SKBR-3 cells in tunicamycin (an inhibitor of N-linked glycosylation) resulted in an increase in sensitivity to DXR (0.1 µM DXR P<0.001) and a decrease in sensitivity to IGF-1 alone and to IGF-1 supplemented with EGF (P<0.001). This report illustrates the importance of N-linked glycosylation in modulating the response of cancer cells to chemotherapeutic and biological treatments and highlights the potential of glycosylation inhibitors as future combination treatments for breast cancer

PI3K/AKT is involved in mediating survival signals that rescue Ewing tumour cells from fibroblast growth factor 2-induced cell death

While in vitro studies had shown that fibroblast growth factor 2 (FGF2) can induce cell death in Ewing tumours, it remained unclear how Ewing tumour cells survive in vivo within a FGF2-rich microenvironment. Serum- and integrin-mediated survival signals were, therefore, studied in adherent monolayer and anchorage-independent colony cell cultures. In a panel of Ewing tumour cell lines, either adhesion to collagen or exposure to serum alone only had a minor protective effect against FGF2. However, both combined led to complete resistance to 5 ng ml−1 FGF2 in three of four FGF2-sensitive cell lines (RD-ES, RM-82 and WE-68), and to an increased survival as compared to other culture conditions in TC-71 cells. Inhibition studies with LY294002 demonstrated that the serum signal is mediated via the phosphoinositide 3-OH kinase/AKT pathway. Thus, Ewing tumour cells escape FGF2-induced cell death by modulating FGF2 signalling. The tumour microenvironment provides the necessary survival signals by integrin-mediated adhesion and soluble serum factor(s). These survival signals warrant further investigation as a potential resistance mechanism to other apoptosis-inducing agents in vivo

Insulin-Like Growth Factors Promote Vasculogenesis in Embryonic Stem Cells

The ability of embryonic stem cells to differentiate into endothelium and form functional blood vessels has been well established and can potentially be harnessed for therapeutic angiogenesis. However, after almost two decades of investigation in this field, limited knowledge exists for directing endothelial differentiation. A better understanding of the cellular mechanisms regulating vasculogenesis is required for the development of embryonic stem cell-based models and therapies. In this study, we elucidated the mechanistic role of insulin-like growth factors (IGF1 and 2) and IGF receptors (IGFR1 and 2) in endothelial differentiation using an embryonic stem cell embryoid body model. Both IGF1 or IGF2 predisposed embryonic stem to differentiate towards a mesodermal lineage, the endothelial precursor germ layer, as well as increased the generation of significantly more endothelial cells at later stages. Inhibition of IGFR1 signaling using neutralizing antibody or a pharmacological inhibitor, picropodophyllin, significantly reduced IGF-induced mesoderm and endothelial precursor cell formation. We confirmed that IGF-IGFR1 signaling stabilizes HIF1α and leads to up-regulation of VEGF during vasculogenesis in embryoid bodies. Understanding the mechanisms that are critical for vasculogenesis in various models will bring us one step closer to enabling cell based therapies for neovascularization

Insulin-like growth factor-I receptor activity is essential for Kaposi's sarcoma growth and survival

Kaposi's sarcoma (KS) is a highly vascular tumour and is the most common neoplasm associated with human immunodeficiency virus (HIV-1) infection. Growth factors, in particular vascular endothelial growth factor (VEGF), have been shown to play an important role in its development. The role of insulin-like growth factors (IGFs) in the pathophysiology of different tumours led us to evaluate the role of IGF system in KS. The IGF-I receptors (IGF-IR) were identified by immunohistochemistry in biopsies taken from patients with different AIDS/HIV-related KS stages and on KSIMM cells (an established KS-derived cell line). Insulin-like growth factor-I is a growth factor for KSIMM cells with a maximum increase of 3H-thymidine incorporation of 130±27.6% (P<0.05) similar to that induced by VEGF and with which it is additive (281±13%) (P<0.05). Moreover, specific blockade of the receptor (either by α IR3 antibody or by picropodophyllin, a recently described selective IGF-IR tyrosine phosphorylation inhibitor) induced KSIMM apoptosis, suggesting that IGF-IR agonists (IGF-I and -II) mediate antiapoptotic signals for these cells. We were able to identify an autocrine loop essential for KSIMM cell survival in which IGF-II is the IGF-IR agonist secreted by the cells. In conclusion, IGF-I pathway inhibition is a promising therapeutical approach for KS tumours