Exogenous Lipocalin 2 Ameliorates Acute Rejection in a Mouse Model of Renal Transplantation.

Lipocalin 2 (Lcn2) is rapidly produced by damaged nephron epithelia and is one of the most promising new markers of renal injury, delayed graft function and acute allograft rejection (AR); however, the functional importance of Lcn2 in renal transplantation is largely unknown. To understand the role of Lcn2 in renal AR, kidneys from Balb/c mice were transplanted into C57Bl/6 mice and vice versa and analyzed for morphological and physiological outcomes of AR at posttransplantation days 3, 5, and 7. The allografts showed a steady increase in intensity of interstitial infiltration, tubulitis and periarterial aggregation of lymphocytes associated with a substantial elevation in serum levels of creatinine, urea and Lcn2. Perioperative administration of recombinant Lcn2:siderophore:Fe complex (rLcn2) to recipients resulted in functional and morphological amelioration of the allograft at day 7 almost as efficiently as daily immunosuppression with cyclosporine A (CsA). No significant differences were observed in various donor-recipient combinations (C57Bl/6 wild-type and Lcn2(-/-) , Balb/c donors and recipients). Histochemical analyses of the allografts showed reduced cell death in recipients treated with rLcn2 or CsA. These results demonstrate that Lcn2 plays an important role in reducing the extent of kidney AR and indicate the therapeutic potential of Lcn2 in transplantation.

Influence of iodinated contrast media on the activities of histamine inactivating enzymes diamine oxidase and histamine N-methyltransferase in vitro

BACKGROUND: Iodinated contrast media can cause pseudoallergic reactions associated with histamine release in significant numbers of patients. To clarify whether these adverse reactions may be aggravated by a compromised histamine catabolism we asked if radiographic contrast agents in vitro inhibit the histamine inactivating enzymes diamine oxidase (DAO) and histamine N-methyltransferase (HMT). METHODS: Nine iodinated contrast agents were tested in vitro. Following pre-incubation of purified porcine kidney DAO and recombinant human HMT with 0.1-10 mM of the respective contrast medium (H2O and specific inhibitors of DAO and HMT as controls) enzyme activities were determined by using radiometric micro assays. RESULTS: None of the contrast media irrespective of their structure showed significant inhibition of the activities of DAO and HMT. Pre-incubation of the enzymes with specific inhibitors led to complete inhibition of the respective enzymatic activity. CONCLUSIONS: The iodinated contrast media tested in vitro did not exhibit inhibition of histamine converting enzymes at physiologically relevant concentrations. However due to the in vitro character of this study these results do not directly reflect the in vivo situation

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Influence of iodinated contrast media on the activities of histamine inactivating enzymes diamine oxidase and histamine N-methyltransferase in vitro.

BACKGROUND: Iodinated contrast media can cause pseudoallergic reactions associated with histamine release in significant numbers of patients. To clarify whether these adverse reactions may be aggravated by a compromised histamine catabolism we asked if radiographic contrast agents in vitro inhibit the histamine inactivating enzymes diamine oxidase (DAO) and histamine N-methyltransferase (HMT). METHODS: Nine iodinated contrast agents were tested in vitro. Following pre-incubation of purified porcine kidney DAO and recombinant human HMT with 0.1-10mM of the respective contrast medium (H2O and specific inhibitors of DAO and HMT as controls) enzyme activities were determined by using radiometric micro assays. RESULTS: None of the contrast media irrespective of their structure showed significant inhibition of the activities of DAO and HMT. Pre-incubation of the enzymes with specific inhibitors led to complete inhibition of the respective enzymatic activity. CONCLUSIONS: The iodinated contrast media tested in vitro did not exhibit inhibition of histamine converting enzymes at physiologically relevant concentrations. However due to the in vitro character of this study these results do not directly reflect the in vivo situation.

Basic fibroblast growth factor isoforms promote axonal elongation and branching of adult sensory neurons in vitro.

Synthesis of the multifunctional cytokine basic fibroblast growth factor (FGF-2) is up-regulated after sciatic nerve lesion. In this study, the effects of low and high molecular weight FGF-2 isoforms on axonal elongation and branching of dissociated rat sensory neurons derived from adult lumbar dorsal root ganglia were investigated. These neurons express FGF receptor (FGFR) type I in the cytoplasmic/membrane compartment and in nuclear speckles. FGF-2 isoforms increase the number of axonal branches in cultures obtained from control rats, but do not promote axonal elongation. In response to a preconditioning lesion, i.e. transection of the sciatic nerve 1 week before culture, the axonal length of ipsilateral lumbar sensory neurons increases two-fold when compared with non-lesioned control rats, and this response is significantly enhanced by FGF-2 isoforms but not by nerve growth factor (NGF). Neurons dissociated from ganglia located contralaterally to the lesion exhibit a smaller increase in axon elongation (30%). The stimulating effects of FGF-2 isoforms on axon growth are fully blocked, and the enhanced regeneration of prelesioned neurons is reduced by the FGFR inhibitor SU5402 suggesting an involvement of endogenous FGF signaling in response to a lesion. The present data support a direct neurotrophic role of the 18 kD and 23 kD FGF-2 isoforms on adult axonal regeneration which may be of therapeutic value in the treatment of peripheral nerve lesions. Furthermore, evidence is provided for an enhanced regenerative capacity not only of preaxotomized neurons but also of homonymous non-axotomized neurons.

Stimulation of gammadelta T cells by aminobisphosphonates and induction of antiplasma cell activity in multiple myeloma.

Bisphosphonates are well-known inhibitors of osteoclastic bone resorption, but recent clinical reports support the possibility of direct or indirect antitumor effects by these compounds. Because bisphosphonates share structural homologies with recently identified gamma delta T-cell ligands, we examined the stimulatory capacity of bisphosphonates to gamma delta T cells and determined whether gamma delta T-cell stimulation by bisphosphonates could be exploited to generate antiplasma cell activity in multiple myeloma (MM). All tested aminobisphosphonates (alendronate, ibandronate, and pamidronate) induced significant expansion of gamma delta T cells (V gamma 9V delta 2++ subset) in peripheral blood mononuclear cell cultures of healthy donors at clinically relevant concentrations (half-maximal activity, 0.9-4 mcmol/L). The proliferative response of gamma delta T cells to aminobisphosphonates was IL-2 dependent, whereas activation of gamma delta T cells (up-regulation of CD25 and CD69) occurred in the absence of exogenous cytokines. Pamidronate-activated gamma delta T cells produced cytokines (ie, interferon [IFN]-gamma) and exhibited specific cytotoxicity against lymphoma (Daudi) and myeloma cell lines (RPMI 8226, U266). Pamidronate-treated bone marrow (BM) cultures of 24 patients with MM showed significantly reduced plasma cell survival compared with untreated cultures, especially in cultures in which activation of BM-gamma delta T cells was evident (14 of 24 patients with MM). gamma delta T-cell depletion from BM cultures completely abrogated the cytoreductive effect on myeloma cells in 2 of 3 tested patients with MM. These results show that aminobisphosphonates stimulating gamma delta T cells have pronounced effects on the immune system, which might contribute to the antitumor effects of these drugs. (Blood. 2000;96:384-392)

Vgamma9/Vdelta2 T cell activation induced by bacterial low molecular mass compounds depends on the 1-deoxy-D-xylulose 5-phosphate pathway of isoprenoid biosynthesis.

Isopentenyl diphosphate (IPP), an important precursor of isoprenoid biosynthesis in prokaryotic and eukaryotic organisms, has been shown to activate Vgamma9/Vdelta2 T cells, the major subset of human gammadelta T cells. The biosynthesis of IPP has been first described as the acetate/mevalonate pathway. Recently, 1-deoxy-D-xylulose 5-phosphate (DOXP) and 2-C-methyl-D-erythritol 4-phosphate have been shown to be key metabolites in the DOXP pathway also leading to the formation of IPP in some eubacteria such as Escherichia coli. Here we report that the low molecular mass fraction of extracts from bacteria using the DOXP pathway induces Vgamma9/Vdelta2 T cell activation, while analogous preparations from bacteria using the classical mevalonate pathway fail to do so. Addition of 1-deoxy-D-xylulose potentiates the ability of E. coli extracts to activate Vgamma9/Vdelta2 T cells. As the amounts of IPP present in the bacterial preparations are not sufficient to induce significant Vgamma9/Vdelta2 T cell activation, our data suggest that compounds other than IPP associated with the DOXP pathway are responsible for Vgamma9/Vdelta2 T cell activation.