Differential impact of L-arginine deprivation on the activation and effector functions of T cells and macrophages

The metabolism of the amino acid l-arginine is emerging as a crucial mechanism for the regulation of immune responses. Here, we characterized the impact of l-arginine deprivation on T cell and macrophage (MΦ) effector functions: We show that whereas l-arginine is required unconditionally for T cell activation, MΦ can up-regulate activation markers and produce cytokines and chemokines in the absence of l-arginine. Furthermore, we show that l-arginine deprivation does not affect the capacity of activated MΦ to up-regulate l-arginine-metabolizing enzymes such as inducible NO synthase and arginase 1. Thus, our results show that to exert their effector functions, T cells and MΦ have different requirements for l-arginine.

Ursodeoxycholic acid reduces lipid peroxidation and mucin secretagogue activity in gallbladder bile of patients with cholesterol gallstones

BACKGROUND

Recently it has been postulated that gallbladder mucin hypersecretion observed in the pathogenesis of cholesterol gallstone disease may be induced by biliary lipid peroxidation. Ursodeoxycholic acid treatment reduces mucin concentration and the formation of cholesterol crystals in the gallbladder bile of patients with cholesterol gallstones and this effect might be mediated by a decrease of biliary lipid peroxidation.

MATERIAL AND METHODS

In a double-blind, placebo-controlled trial patients with symptomatic cholesterol gallstones received either ursodeoxycholic acid (750 mg daily) (n = 10) or placebo (n = 12) 10-12 days prior to cholecystectomy. As a marker for lipid peroxidation malondialdehyde was measured in bile together with mucin concentration. In addition, the mucin secretagogue activity of the individual bile samples was assessed in cultured dog gallbladder epithelial cells.

RESULTS

Ursodeoxycholic acid therapy resulted in a significant reduction of lipid peroxidation in bile as determined by the biliary malondialdehyde concentration (1.36 +/- 0.28 vs. 2.05 +/- 0.38 micromol L(-1); P < 0.005) and the malondialdehyde (micromol L(-1))/total bile acid (mmol L(-1)) ratio (0.02 +/- 0.005 vs. 0.06 +/- 0.01; P < 0.001). Furthermore, a decrease in mucin concentrations (0.7 +/- 0.3 vs. 1.3 +/- 0.5 mg mL(-1); P < 0.005) and of the mucin secretagogue activity of gallbladder bile (0.9 +/- 0.2 vs. 2.2 +/- 0.3 times control; P < 0.001) was observed.

CONCLUSIONS

The reduction of lipid peroxidation and mucin secretagogue activity of gallbladder bile induced by ursodeoxycholic acid treatment may contribute to the beneficial effects of this drug on gallbladder bile composition and symptoms in cholesterol gallstone patients.

Pathogenesis of CNS involvement in disorders of amino and organic acid metabolism

Inherited disorders of amino and organic acid metabolism have a high cumulative frequency, and despite heterogeneous aetiology and varying clinical presentation, the manifestation of neurological disease is common. It has been demonstrated for some of these diseases that accumulating pathological metabolites are directly involved in the manifestation of neurological disease. Various pathomechanisms have been suggested in different in vitro and in vivo models including an impairment of brain energy metabolism, an imbalance of excitatory and inhibitory neurotransmission, altered transport across the blood-brain barrier and between glial cells and neurons, impairment of myelination and disturbed neuronal efflux of metabolic water. This review summarizes recent knowledge on pathomechanisms involved in phenylketonuria, glutaric aciduria type I, succinic semialdehyde dehydrogenase deficiency and aspartoacylase deficiency with examples, highlighting general as well as disease-specific concepts and their putative impact on treatment.

Efficient in vitro generation of adult multipotent cells from mobilized peripheral blood CD133+ cells

OBJECTIVES

To generate non-haematopoietic tissues from mobilized haematopoietic CD133(+) stem cells.

MATERIALS AND METHODS

Mobilized peripheral blood CD133(+) cells from adult healthy donors were used. In vitro ability of highly enriched CD133(+) cells from mobilized peripheral blood to generate multipotent cells, and their potential to give rise to cells with characteristics of neuroectoderm, endoderm and mesoderm layers was investigated.

RESULTS

We found that a recently identified population of CD45(+) adherent cells generated in vitro after culture of highly purified CD133(+) cells for 3-5 weeks with Flt3/Flk2 ligand and interleukin-6 can, in presence of the appropriate microenvironmental cues, differentiate into neural progenitor-like cells (NPLCs), hepatocyte-like cells and skeletal muscle-like cells. We have termed them to be adult multipotent haematopoietic cells (AMHCs). AMHC-derived NPLCs expressed morphological, phenotypic and molecular markers associated with primary neural progenitor cells. They can differentiate into astrocyte-like cells, neuronal-like cells and oligodendrocyte-like cells. Moreover, AMHC-derived NPLCs produced 3,4-dihydrophenylalanine and dopamine and expressed voltage-activated ion channels, suggesting their functional maturation. In addition, AMHC-derived hepatocyte-like cells and skeletal muscle-like cells, showed typical morphological features and expressed primary tissue-associated proteins.

CONCLUSION

Our data demonstrate that AMHCs may therefore serve as a novel source of adult multipotent cells for autologous replacement cell therapies.

Novel insight into the regulation of GSH biosynthesis in higher plants

In higher plants, the redox-active tripeptide glutathione (GSH) fulfills a plethora of functions. These include its pivotal role for maintaining the cellular redox poise and its involvement in detoxification of heavy metals and xenobiotics. Intimately linked to these functions, GSH also acts as a cellular signal, mediating control of enzyme and/or regulatory protein activities, either directly or via glutaredoxins. The redox potential of the GSH/GSSG couple is not only affected by the GSH/GSSG ratio but also by changes in GSH synthesis and/or degradation. As this couple operates as redox buffer in several cellular compartments, the regulation of GSH biosynthesis and transport (both intra- and intercellularly) are fundamental to the maintenance of cellular redox homeostasis during plant development and, even more so, when plants are exposed to biotic or abiotic stress. This review highlights novel aspects of GSH biosynthesis and transport with a focus on the regulation of the GSH1 (= gamma-glutamylcysteine synthetase) enzyme. Interestingly, GSH1 appears to be exclusively confined to the plastids, whereas the second biosynthetic enzyme, GSH2, is predominantly localized in the cytosol. GSH1 expression and enzyme activity are under multiple controls, extending from transcriptional regulation to post-translational redox control. Now that the plant GSH1 protein structure has been solved, the molecular basis of GSH1 function and redox regulation can be addressed. The review concludes with a discussion of the simultaneous changes observed for GSH synthesis, transport, and metabolism during Cd-induced phytochelatin accumulation.

Animal serum-free culture conditions for isolation and expansion of multipotent mesenchymal stromal cells from human BM

BACKGROUND

Multipotent mesenchymal stromal cells (MSC) have become important tools in regenerative and transplantation medicine. Rapidly increasing numbers of patients are receiving in vitro-expanded MSC. Culture conditions typically include FSC because human serum does not fully support growth of human MSC in vitro (MSC(FCS)). Concerns regarding BSE, other infectious complications and host immune reactions have fueled investigation of alternative culture supplements.

METHODS

As PDGF has long been identified as a growth factor for MSC, we tested media supplementation with platelet lysate for support of MSC proliferation.

RESULTS

We found that primary cultures of BM-derived MSC can be established with animal serum-free media containing fresh frozen plasma and platelets (MSC(FFPP)). Moreover, MSC(FFPP) showed vigorous proliferation that was superior to classical culture conditions containing FCS. MSC(FFPP) morphology was equivalent to MSC(FCS), and MSC(FFPP) expressed CD73, CD90, CD105, CD106, CD146 and HLA-ABC while being negative for CD34, CD45 and surface HLA-DR, as expected. In addition to being phenotypically identical, MSC(FFPP) could efficiently differentiate into adipocytes and osteoblasts. In terms of immune regulatory properties, MSC(FFPP) were indistinguishable from MSC(FCS). Proliferation of PBMC induced by IL-2 in combination with OKT-3 or by PHA was inhibited in the presence of MSC(FFPP).

DISCUSSION

Taken together, FCS can be replaced safely by FFPP in cultures of MSC for clinical purposes.

Impact of low copy repeats on the generation of balanced and unbalanced chromosomal aberrations in mental retardation

Low copy repeats (LCRs) are stretches of duplicated DNA that are more than 1 kb in size and share a sequence similarity that exceeds 90%. Non-allelic homologous recombination (NAHR) between highly similar LCRs has been implicated in numerous genomic disorders. This study aimed at defining the impact of LCRs on the generation of balanced and unbalanced chromosomal rearrangements in mentally retarded patients. A cohort of 22 patients, preselected for the presence of submicroscopic imbalances, was analysed using submegabase resolution tiling path array CGH and the results were compared with a set of 41 patients with balanced translocations and breakpoints that were mapped to the BAC level by FISH. Our data indicate an accumulation of LCRs at breakpoints of both balanced and unbalanced rearrangements. LCRs with high sequence similarity in both breakpoint regions, suggesting NAHR as the most likely cause of rearrangement, were observed in 6/22 patients with chromosomal imbalances, but not in any of the balanced translocation cases studied. In case of chromosomal imbalances, the likelihood of NAHR seems to be inversely related to the size of the aberration. Our data also suggest the presence of additional mechanisms coinciding with or dependent on the presence of LCRs that may induce an increased instability at these chromosomal sites.

Is serological testing a reliable tool in laboratory diagnosis of syphilis? Meta-analysis of eight external quality control surveys performed by the german infection serology proficiency testing program

The accuracy of diagnostic tests is critical for successful control of epidemic outbreaks of syphilis. The reliability of syphilis serology in the nonspecialist laboratory has always been questioned, but actual data dealing with this issue are sparse. Here, the results of eight proficiency testing sentinel surveys for diagnostic laboratories in Germany between 2000 and 2003 were analyzed. Screening tests such as Treponema pallidum hemagglutination assay (mean accuracy, 91.4% [qualitative], 75.4% [quantitative]), Treponema pallidum particle agglutination assay (mean accuracy, 98.1% [qualitative], 82.9% [quantitative]), and enzyme-linked immunosorbent assays (ELISAs) (mean qualitative accuracy, 95%) were more reliable than Venereal Disease Research Laboratory (VDRL) testing (mean accuracy, 89.6% [qualitative], 71.1% [quantitative]), the fluorescent treponemal antibody absorption test (FTA-ABS) (mean accuracy, 88% [qualitative], 65.8% [quantitative]), and immunoblot assays (mean qualitative accuracy, 87.3%). Clearly, immunoglobulin M (IgM) tests were more difficult to manage than IgG tests. False-negative results for samples that have been unambiguously determined to be IgM and anti-lipoid antibody positive accounted for 4.7% of results in the IgM ELISA, 6.9% in the VDRL test, 18.5% in the IgM FTA-ABS, and 23.0% in the IgM immunoblot assay. For negative samples, the mean percentage of false-positive results was 4.1% in the VDRL test, 5.4% in the IgM ELISA, 0.7% in the IgM FTA-ABS, and 1.4% in the IgM immunoblot assay. On average, 18.3% of participants misclassified samples from patients with active syphilis as past infection without indicating the need for further treatment. Moreover, 10.2% of laboratories wrongly reported serological evidence for active infection in samples from patients with past syphilis or in sera from seronegative blood donors. Consequently, the continuous participation of laboratories in proficiency testing and further standardization of tests is strongly recommended to achieve better quality of syphilis serology.

Haploidentical Stem Cell Transplantation in Patients with Pediatric Solid Tumors: Preliminary Results of a Pilot Study and Analysis of Graft versus Tumor Effects

Pediatric patients with relapsed metastatic tumors have a poor prognosis and new treatment strategies are warranted. We present preliminary results of a pilot study, evaluating the feasibility and toxicity of transplantation of haploidentical T and B cell depleted grafts with high numbers of NK cells. 6 patients with relapsed metastatic neuroblastomas (n = 4), rhabdomyosarcoma (n = 1) or Ewing's sarcoma (n = 1) after previous autologous transplantation received CD3/CD19 depleted grafts from mismatched family donors with a median number of 16 x 10 (6)/kg stem cells, 167 x 10 (6)/kg Natural Killer cells and only 5.4 x 10 (4)/kg residual T cells. A melphalan-based, reduced intensity conditioning was used. Despite pretransplant chemotherapy, patients entered transplantation with significant tumor burden. Primary engraftment occurred in 6/6 patients. One patient had secondary graft failure. Hematopoietic recovery was rapid (ANC > 0.5 x 10 (9)/L: 11 days (9-12); independence from platelet substitution: 8 days (7-11)). Four patients had acute GvHD grade II, limited chronic GvHD was observed in 2 patients. No transplant-related mortality and only low toxicity occurred. Four patients died from progression, two patients are alive. Overall median survival time is 6 months (2-11) to date. Analysis of posttransplant NK cell function revealed stable cytotoxic activity against K562 targets, whereas activity against neuroblastoma targets was low. Stimulation with cytokines and use of appropriate antibodies clearly enhanced specific lysis in vitro. In summary, these preliminary results indicate the feasibility and low toxicity even in intensively pre-treated patients with neuroblastomas/sarcomas. This approach may form the basis for posttransplant immunomodulation and other therapeutic strategies. Further experience is warranted to evaluate the method.

CXCR4 chemokine receptor mediates prostate tumor cell adhesion through alpha5 and beta3 integrins

The mechanisms leading to prostate cancer metastasis are not understood completely. Although there is evidence that the CXC chemokine receptor (CXCR) 4 and its ligand CXCL12 may regulate tumor dissemination, their role in prostate cancer is controversial. We examined CXCR4 expression and functionality, and explored CXCL12-triggered adhesion of prostate tumor cells to human endothelium or to extracellular matrix proteins laminin, collagen, and fibronectin. Although little CXCR4 was expressed on LNCaP and DU-145 prostate tumor cells, CXCR4 was still active, enabling the cells to migrate toward a CXCL12 gradient. CXCL12 induced elevated adhesion to the endothelial cell monolayer and to immobilized fibronectin, laminin, and collagen. Anti-CXCR4 antibodies or CXCR4 knock out significantly impaired CXCL12-triggered tumor cell binding. The effects observed did not depend on CXCR4 surface expression level. Rather, CXCR4-mediated adhesion was established by alpha5 and beta3 integrin subunits and took place in the presence of reduced p38 and p38 phosphorylation. These data show that chemoattractive mechanisms are involved in adhesion processes of prostate cancer cells, and that binding of CXCL12 to its receptor leads to enhanced expression of alpha5 and beta3 integrins. The findings provide a link between chemokine receptor expression and integrin-triggered tumor dissemination.

Biochemical characterization of MelJ and MelK

Melithiazol and myxothiazol are two myxobacterial metabolites that are highly efficient electron transport inhibitors of the respiratory chain. MelJ and MelK encoded in the melithiazol biosynthetic gene cluster were recently shown to be involved in the formation of the methyl ester from a hypothetical amide intermediate. In vivo studies suggest that the structurally highly similar amide myxothiazol A can be used as a substrate mimic of the hypothetical melithiazol amide to characterize the hydrolase MelJ. Both enzymes were produced in Escherichia coli as intein chitin fusion proteins and were purified using affinity chromatography. MelJ was found to catalyse the conversion of the amide myxothiazol to free myxothiazol acid. The formerly unknown myxothiazol acid was purified and used as a substrate for the methyl transferase MelK which methylates the compound using S-adenosyl-methionine as cosubstrate. Sequence analyses suggest that MelJ and MelK are members of the amidase signature family and of a new subclass of methyltransferases, respectively. Kinetic analyses point at a very high substrate specificity for both enzymes. Furthermore, the in vitro reconstitution of a unique mechanism of methyl ester formation found in myxobacteria is reported.

Vergleich von Früh- und Spätrehabilitation bei zerebral geschädigten Patienten mit Gesichtsfelddefekten

BACKGROUND

Most rehabilitation studies on visual field deficits after stroke or trauma are conducted after completion of the spontaneous recovery phase. However, the question arises whether more extensive visual field improvements can be reached when the training starts very soon after the lesion.

METHODS

In this study, the results of 26 patients who began visual restoration therapy within the first 12 months after the lesion were compared with an age-related group whose lesions were more than 1 year old.

RESULTS

The early-onset group showed an improvement of 8% in computer campimetry and 10-15% in conventional automated perimetry. The late-onset group had 13.5% improvement in campimetry and 20% in perimetry.

CONCLUSION

In contrast to our assumptions, there was no significant difference between the groups. Furthermore, the late-onset group showed considerably greater improvement than the early-onset group. It is proposed that pronounced attention deficits soon after brain damage may complicate the training.

A comparison between three graft manipulation methods for haploidentical stem cell transplantation in pediatric patients: preliminary results of a pilot study

Transplantation of hematopoietic stem cells from mismatched related donors makes a potential donor available for every child in need of stem cell transplantation. Here, we compare three different graft manipulation methods in patients with leukemias and lymphomas: positive selection of stem cells with either CD34 (n = 39) or CD133-coated magnetic microbeads (n = 14) and a new strategy which depletes T- and B-cells through the use of CD3- and CD19-coated microbeads (n = 11). Median purity of stem cells was comparable after CD34 (+)-selection and CD133 (+)-selection, whereas stem cells were only slightly enriched after CD3 (+)/CD19 (+)-depletion (97.5 %, 93.4 % and 1.02 %). Indirect depletion of T-cells by positive selection resulted in 1 x 10 (4) (median) residual CD3 (+)-cells/kg (0.7-3 x 10 (4)). Patients with CD3/CD19-depleted grafts received 3.2 x 10 (4) (median) (0.7-16 x 10 (4)) residual T-cells/kg. Those grafts also comprised NK-cells (median number: 86 x 10 (6)/kg), dendritic cells and monocytes/granulocytes. Primary engraftment of the stem cell products was comparable after CD34- and CD133-selection (85 and 72 %). In the CD3/CD19 group, 91 % had a primary engraftment. After reconditioning, all patients (64/64) were finally engrafted. Patients with CD34-selected or CD133-selected grafts had similar incidences of a GvHD II-IV (3 and 7 %), whereas a GvHD was slightly increased in patients receiving CD3/CD19-depleted cells (27 %). Reconstitution of CD3 (+) T-cells was faster in the CD3/CD19 group than in the CD34 or CD133 group. These preliminary results indicate, that CD3/CD19-selected grafts may be advantageous regarding engraftment and immunoreconstitution. Since effector cell with potential antileukemic activity are cotransfused, such grafts may be suited in particular for patients with insufficient remission.

Prostate tumor CXC-chemokine profile correlates with cell adhesion to endothelium and extracellular matrix

Though chemokines of the CXC family are thought to play key roles in neoplastic transformation and tumor invasion, information about CXC chemokines in prostate cancer is sparse. To evaluate the involvement of CXC chemokines in prostate cancer, we analyzed the CXC coding mRNA of both chemokine ligands (CXCL) and chemokine receptors (CXCR), using the prostate carcinoma cell lines PC-3, DU-145 and LNCaP. CXCR proteins were further evaluated by Western blot, CXCR surface expression by flow cytometry and confocal microscopy. The expression pattern was correlated to adherence of the tumor cells to an endothelial cell monolayer or to extracellular matrix components. Based on growth and adhesion capacity, PC-3 and DU-145 were identified to be highly aggressive tumor cells (PC-3>DU-145), whereas LNCaP belonged to the low aggressive phenotype. CXCL1, CXCL3, CXCL5 and CXCL6 mRNA, chemokines with pro-angiogenic activity, were strongly expressed in DU-145 and PC-3, but not in LNCaP. CXCR3 and CXCR4 surface level differed in the following order: LNCaP>DU-145>PC-3. The differentiation factor, fatty acid valproic acid, induced intracellular CXCR accumulation. Therefore, prostate tumor malignancy might be accompanied by enhanced synthesis of angiogenesis stimulating CXC chemokines. Further, shifting CXCR3 and CXCR4 from the cell surface to the cytoplasm might activate pro-tumoral signalling events and indicate progression from a low to a highly aggressive phenotype.

SKY and FISH analysis of radiation-induced chromosome aberrations: a comparison of whole and partial genome analysis

For a retrospective dose estimation of human exposure to ionising radiation, a partial genome analysis is routinely used to quantify radiation-induced chromosome aberrations. For this purpose, fluorescence in situ hybridisation (FISH) with whole chromosome painting probes for selected chromosomes is usually applied covering about 20% of the whole genome. Since genome-wide screening techniques like spectral karyotyping (SKY) and multiplex FISH (mFISH) have been developed the detection of radiation-induced aberrations within the whole genome has now become feasible. To determine the correspondence between partial and whole genome analysis of radiation-induced chromosome aberrations, they were measured comprehensively in this study using in vitro irradiated blood samples from three donors. We were able to demonstrate that comparable results can be detected with both approaches. However, complex aberrations might be misinterpreted by partial genome analysis. We therefore conclude that whole genome analysis by SKY is useful especially in the high dose range to correct aberration data for complex exchange aberrations.

Bcl-2 mediated inhibition of erucylphosphocholine-induced apoptosis depends on its subcellular localisation

The synthetic phospholipid derivative erucylphosphocholine (ErPC) is a potent inducer of apoptosis in human tumor cell lines. This membrane-targeted drug induces apoptosis independently from death receptor signaling through a mitochondrial pathway that is inhibited by over-expression of Bcl-2. Within the cell, Bcl-2 resides in membranes of mitochondria, endoplasmic reticulum (ER) and the nucleus. However, the importance of its subcellular localisation in distinct organelles for protection against apoptosis is not completely understood. To investigate the impact of Bcl-2 localised at defined subcellular compartments on its protective effects against ErPC-induced apoptosis, Bcl-2 expression was directed to the outer membrane of the mitochondria or the ER of Jurkat T Lymphoma cells, using Bcl-2 mutants with modified membrane anchors. The mitochondrial insertion sequence of ActA directed Bcl-2 to the mitochondria (Bcl-2/MT), the ER-specific sequence of cytochrome b5 to the ER (Bcl-2/ER). Additionally, Jurkat cells expressing wild-type Bcl-2 (Bcl-2/WT) or a transmembrane domain-lacking mutant (Bcl-2/DeltaTM) were employed. While restricted expression of Bcl-2 either at membranes of the mitochondria or the ER strongly interfered with ErPC-induced mitochondrial damage and apoptosis, cytosolic Bcl-2/DeltaTM exhibited only reduced protection. Thus, membrane localisation of Bcl-2 is a prerequisite for substantial protection against ErPC-induced apoptosis. For efficient long-term inhibition of ErPC-induced apoptosis Bcl-2 had to be present in the membranes of both compartments, the ER and the mitochondria. The finding that ER-targeted Bcl-2 interferes with ErPC-induced mitochondrial damage points to an involvement of the ER in apoptosis signaling upstream of the mitochondria and to a crosstalk between both compartments.