PubMed Health⌕ Search

Biomedical subjects

R Buelow

Publications and source records attributed to R Buelow.

At least 19 recordsLinked to original sources
PubMed2006

Improved long-term graft survival after HO-1 induction in brain-dead donors.

Brain death (BD) of the donor, a risk factor uniquely relevant for organs derived from cadaver donors, influences organ quality by induction of various inflammatory events. Consequently ischemia/reperfusion injury is deteriorated and acute and chronic rejections accelerated. Donor treatment might be an approach to improve the quality of the graft. The induction of heme oxygenase 1 (HO-1) has been shown to exert beneficial effects in living-donor transplantation models. Therefore, we examined the impact of donor treatment with the selective inducer of HO-1, cobalt protoporphyrin (CoPP), on organ quality and transplant outcome in a standardized BD model in a F344-->LEW kidney transplant rat model. Immediately after BD induction, donor animals were administered a single dose of CoPP (5 mg/kg) and in control groups, HO-1 activity was blocked with zinc protoporphyrin (ZnPP, 20 mg/kg). Recipients of organs from brain-dead donors treated with CoPP survived significantly better than those from untreated brain-dead donors (p < 0.05) and intra-graft analysis showed improved histology (p < 0.05). Blockade of HO-1 with ZnPP decreased the survival rates (p < 0.05) comparable to untreated brain-dead donors. Our results demonstrate that HO-1 induction by one single treatment of CoPP in brain-dead donors leads to enhanced allograft survival.

Animals↗
PubMed2005

Sequence analysis of 0.4 megabases of the rabbit germline immunoglobulin kappa1 light chain locus.

Two rabbit germline bacterial artificial chromosome (BAC) libraries from animals with the b5 and b4 allotype were screened with probes specific for the immunoglobulin kappa1 light chain locus. Two partially overlapping BAC clones containing Vkappa elements of b5 allotype were isolated from the b5 library and one BAC clone containing Jkappa1, Ckappa and Vkappa was isolated from the b4 library. These three BAC clones were sequenced. They span about 0.4 MB of the rabbit Ig kappa1 light chain locus including 36 Vkappa elements, five J elements and the coding region of Ckappa1. The organization of the locus and the potential function of newly identified functional and structural elements are discussed.

Amino Acid Sequence↗
PubMed2004

Induction of long-term cardiac allograft survival by heme oxygenase-1 gene transfer.

Elevated expression of heme oxygenase-1 (HO-1), an intracellular enzyme that degrades heme into carbon monoxide (CO), biliverdine and free iron, has anti-inflammatory and antiapoptotic effects in diverse models. Here, we analyzed the effects of specific overexpression of HO-1 following adenovirus-mediated (AdHO-1) gene transfer in an acute cardiac allograft rejection model. The intragraft (i.g.) injection of AdHO-1 into cardiac allografts, as well as intramuscular (i.m.) or intravenous (i.v.) administration, prolonged allograft survival with, respectively, 13.3, 62.5 and 80% of the grafts surviving long term (>100 days), whereas control grafts were rejected with acute kinetics. HO-1 overexpression was associated with inhibited allogeneic responses in MLRs using graft-infiltrating leukocytes and splenocytes, but not with lymph node cells. The inhibition of splenocyte proliferation was mediated by soluble factors and was dependent on the presence of APCs, since purified T cells proliferated normally. i.v. but not i.g. AdHO-1 administration decreased the number of graft-infiltrating leukocytes, cytokine mRNA accumulation and apoptosis in transplanted hearts, whereas i.v. and i.g. AdHO-1 did not modify normal immune responses against cognate antigens, indicating that there was no general immunosuppression. These results indicate that HO-1 overexpression prolongs the survival of vascularized allografts by promoting tolerogenic mechanisms acting on allogeneic cellular immune responses.

Adenoviridae↗
PubMed2003

Generation of heme oxygenase-1-transgenic rats.

Heme oxygenase-1 (HO-1) expression protects cells from a variety of cellular insults and inhibits inflammation. However, its role in the regulation of immune responses has not yet been clearly established. We generated HO-1 transgenic rats to directly test the impact of HO-1 on the different immune mechanisms. To temporally control the expression of HO-1, we used a one-plasmid tetracycline (tet)-inducible system. This plasmid contains the H-2K(b) promoter, which transcribes the tet transactivator (tTA) and expression of a human HO-1 cDNA is obtained in the absence of tetracycline. The DNA construct was microinjected into one-cell rat embryos and mothers and pups were maintained with tetracycline. Eight transgenic founders were obtained. Analysis of transgene expression in the absence of tet showed that 2 lines (12.4 and 12.6) expressed HO-1 mRNA in several organs (as detected by reverse transcription polymerase chain reaction) and at the protein level only in the thymus. Expression levels of transgene-derived HO-1 increased after withdrawal of tet compared with transgenic rats maintained with tet, as detected by analysis of mRNA levels by quantitative real-time reverse transcription polymerase chain reaction. Gross examination and histopathological analysis of several organs in both lines showed no anomalies. Thymocytes and splenocytes of both lines showed normal cell subpopulations and allogeneic proliferation compared with controls. Systemic immune responses against cognate antigens were normal in both lines, as evaluated by the proliferation of lymph node cells and the production of antibodies against keyhole limpet hemocyanin after immunization. Animals from line 12.6 rejected transplanted allogeneic hearts with the same kinetics as controls. In conclusion, short-term induction of HO-1 overexpression did not modify immune responses compared to those of control non-transgenic animals.

Animals↗
PubMed2003

RDP58, a novel immunomodulatory peptide with anti-inflammatory effects. A pharmacological study in trinitrobenzene sulphonic acid colitis and Crohn disease.

BACKGROUND: Tumour necrosis factor (TNF) plays a key role in the pathogenesis of Crohn disease (CD). RDP58 is a novel anti-inflammatory decapeptide which was developed using a novel rational design strategy. Recently, RDP58 has proved to be a potent inhibitor of TNF production at a post-transcriptional step. The aims of this study were to investigate the anti-inflammatory properties of RDP58 ex vivo in human CD and in vivo in an experimental model colitis. METHODS: Biopsies and lamina propria mononuclear cells from inflamed colonic mucosa of 18 CD patients were cultured for 24 h in the presence or absence of RDP58. TNF was quantified in a bioassay: interferon (IFN)-gamma and interleukin (IL)-1beta levels were measured by enzyme-linked immunosorbent assays. Colitis was induced by intra-rectal administration of 2, 4, 6 trinitrobenzene sulphonic acid (TNBS) in rats. Inflammation was assessed following 7 days of oral therapy with RDP58 or vehicle alone. RESULTS: RDP58 led to decreased TNF and IFN-gamma (but not IL-1beta) production by biopsies and lamina propria mononuclear cells from CD patients. In rats with TNBS-induced colitis, oral RDP58 therapy reduced weight loss and diarrhoea and improved macroscopic and histological inflammation scores. CONCLUSIONS: Our results suggest that RDP58 may be an effective therapy for CD with the clinical advantage of an oral administration.

Adolescent↗
PubMed2002

RDP58, a locally active TNF inhibitor, is effective in the dextran sulphate mouse model of chronic colitis.

OBJECTIVE AND DESIGN: RDP58 is a novel anti-inflammatory peptide that inhibits TNF synthesis and upregulates heme oxygenase-1. RDP58 therapy was evaluated in the dextran sodium sulphate (DSS) model of chronic colitis. MATERIAL: Colitis was induced by giving DSS to mice (n = 8 animals/group). Toxicity studies were done in Rhesus monkeys (n = 5), dogs (n = 3) and mice (n = 10). TREATMENT: In colitis, mice were treated with p.o. vehicle (saline), RDP58 (5 and 10 mg/kg/day) or 5-ASA (50 mg/kg/day). METHODS: Disease activity index (DAI) was used as the endpoint of efficacy. RESULTS: RDP58 therapy significantly reduced DAI and histological scores in all animals. DAI scores in RDP58 treated animals declined faster than 5-ASA. RDP58 at 5 or 10 mg/ kg/day significantly reduced DAI compared to 5-ASA. RDP58 significantly reduced acute, chronic and total inflammation scores. It enhanced re-epithelialization by reducing crypt scores. RDP58 was not bioavailable and was well tolerated. CONCLUSIONS: Therapeutic efficacy of RDP58 combined with a lack of bioavailibility and toxicity suggest that RDP58 may be a promising new therapeutic for IBD.

Animals↗
PubMed2002

Inhibition of graft arteriosclerosis development in rat aortas following heme oxygenase-1 gene transfer.

Heme oxygenase 1 (HO-1) is an enzyme which degrades heme into tree end products: biliverdin, free iron and carbon monoxide. This enzyme has recently been shown to have anti-inflammatory and tissue protective effects. HO-1 expression is involved in organ protection in pathological situations, and immunosuppressive treatments resulting in indefinite graft survival without chronic rejection have been associated with HO-1 expression by cells of the vessel wall. The aim of this study was to analyze the effect of specific HO-1 overexpression. We used a recombinant adenovirus coding for human HO-1 cDNA in a rat aorta chronic rejection model, 30 days after transplantation. Control groups included rats non treated or treated with a non-coding adenovirus Addl324. We first demonstrated that AdHO-1 was efficiently expressed in endothelial cells in vitro, and in rat aortas ex vivo after adenovirus gene transfer. We found that intimal thickening in AdHO-1 treated aortas (10.8 +/- 3.8%, n=5) was significantly decreased compared to untreated (21.2 +/- 5.6%, n = 5) or Addl324-treated (21.1 +/- 1.2%, n = 4) aortas. Immunohistology showed that treatment with AdHO-1 resulted in a significant reduction in leukocyte infiltration and a decreasing number of VSMC in the intima, compared to Addl324-treated aortas. However, this effect of HO-1 on chronic rejection did not imply modifications on numbers of apoptotic cells in the graft or of alloantibody levels. We have demonstrated, for the first time, that specific HO-1 overexpression following gene transfer of HO-1 inhibited chronic rejection by reducing leukocyte and VSMC infiltration of the aorta intima.

Adenoviridae↗
PubMed2002

Orally administered RDP58 reduces the severity of dextran sodium sulphate induced colitis.

Oral administration of the novel anti-inflammatory peptide RDP58 markedly reduced the severity of dextran sulphate sodium (DSS) colitis as determined by clinical and quantitative histological criteria. The architecture of the colonic epithelium in DSS treated mice receiving RDP58 remained relatively normal compared with that of control DSS treated animals. 5-Bromo-2'-deoxyuridine (BrdU) labelling studies showed a pronounced inhibition of colonic epithelial cell proliferation during DSS treatment, which was partially reversed by RDP58 therapy. Remarkably, RDP58 almost completely prevented colonic epithelial cell death induced by DSS treatment. RDP58 therapy also inhibited the accumulation of neutrophils in the colon of DSS treated mice and effectively down regulated tumour necrosis factor (TNF) expression. Preservation of the intestinal mucosa by RDP58 may thus derive from its influence on TNF expression as well as additional anti-inflammatory properties. These findings indicate that RDP58 represents a new, orally available agent potentially useful in the treatment of inflammatory bowel disease.

Acute Disease↗
PubMed2001

Total and active thymoglobulin levels: effects of dose and sensitization on serum concentrations.

A group of 79 renal transplant patients undergoing acute rejection episodes were treated with Thymoglobulin (rabbit anti-thymocyte globulin), 1.5 mg/kg/day for 6-14 days as part of a double-blinded trial comparing the efficacy of Thymoglobulin and Atgam (horse anti-thymocyte globulin). Serial serum samples from the patients were tested to determine the level of Thymoglobulin (i.e. rabbit IgG levels = total Thymoglobulin) and anti-Thymoglobulin using ELISAs. Antibodies binding to human lymphocytes (active Thymoglobulin), were determined by flow cytometry; no correlation was seen between treatment efficacy and either active or total Thymoglobulin concentrations; the overall treatment success rate was 86%. Pharmacokinetics of total and active Thymoglobulin were distinctly different; active Thymoglobulin disappeared much more rapidly: only 12% of patients had detectable active Thymoglobulin by day 90 compared to 81% of patients with detectable total Thymoglobulin; percent active Thymoglobulin decreased from a peak of 0.56-0.7% during treatment, to 0.07-0.35% by day 21, and less than 0.14% by day 30. Thymoglobulin and active Thymoglobulin concentrations were modeled by multiple regression. Using dose number and sensitization as independent variables, 47-76% of the variability seen in interpatient Thymoglobulin levels could be explained, while for active Thymoglobulin levels, the measured variables accounted for 13-48% of the observed interpatient variation. We conclude that: (1) for a group of patients receiving primary Thymoglobulin treatment (averaging nine full and one partial dose per patient), neither Thymoglobulin nor active Thymoglobulin levels are predictive of treatment outcome; (2) active Thymoglobulin disappears more rapidly from the circulation than total Thymoglobulin; and (3) patients that develop anti-rabbit IgG antibodies clear Thymoglobulin and active Thymoglobulin more rapidly than unsensitized patients.

Animals↗
PubMed2001

Inhibition of cutaneous UV light-induced tumor necrosis factor-alpha protein production by Allotrap 1258, a novel immunomodulatory peptide.

Peptides derived from the heavy chain of the HLA Class-I molecules have been shown to modulate immune responses both in vivo and in vitro. Using a computer-aided rational drug design approach, novel immunomodulatory peptides were designed based on peptide 2702.75-85, derived from HLA-B2702. Several peptides were identified which had increased immunomodulatory activity, including peptides RDP1258 and its D-isomer the peptide Allotrap 1258. The present study using Skh/hr hairless mouse skin model evaluated the in vivo effects of Allotrap 1258 on acute UVB-induced skin inflammation. Here we demonstrate that intraperitoneal administration of Allotrap 1258 1 h prior to UV exposure resulted in significantly diminished levels of UV-induced tumor necrosis factor (TNF)-alpha protein production in the epidermis but had no effect on other parameters of the acute UV-induced inflammatory response. By virtue of its ability to suppress TNF-alpha protein production, Allotrap 1258 could prove to be an effective modulator of inflammatory responses.

Adjuvants, Immunologic↗
PubMed2001

Heme oxygenase-1 overexpression protects rat livers from ischemia/reperfusion injury with extended cold preservation.

This study analyzes the effects and mechanisms of heme oxygenase-1 (HO-1)-mediated cytoprotection in rat livers exposed to cold preservation. In the first series, rats were pretreated with cobalt protoporphyrin (CoPP) or zinc protoporphyrin (ZnPP), HO-1 inducer and antagonist, respectively. Livers were stored at 4 degrees C for 24 h, and then perfused ex vivo for 2 h. Livers pretreated with CoPP had significantly higher portal venous blood flow and increased total bile production, as compared with the ZnPP group. This correlated with histologic (Banff) criteria of hepatocyte injury/liver function. In the second series, rat livers were stored at 4 degrees C for 24 h or 40 h, and then transplanted into syngeneic recipients. After 24 h of preservation, 80% of rats bearing CoPP-pretreated liver grafts survived 21 days (vs. 50% in controls). After 40h of cold preservation, liver transplant survival at day 1, 7 and 21 for the CoPP group was: 100%, 71% and 57%, respectively (vs. 50%, 50% and 33% in controls). This correlated with improved hepatic function/histologic (Suzuki) criteria of hepatocyte injury after HO-1 overexpression (immunohistology/Western blots) by infiltrating macrophages. This study documents the potential utility of HO-1-inducing agents in preventing ischemia/reperfusion injury resulting from prolonged storage of liver transplants.

Animals↗
PubMed2000

Anti-Gal antibodies in humans and 1, 3alpha-galactosyltransferase knock-out mice.

BACKGROUND: Due to the absence of alphaGAL epitopes, humans and galactosyltransferase knock-out (GALT/ KO) mice express high levels of anti-Gal antibodies. We describe the properties of mouse anti-GAL antibodies. METHODS: Anti-GAL IgG antibodies were quantified by affinity purification. Antibody affinities and avidities were determined in direct binding and competition assays. Antibody-mediated rejection was investigated using hyperimmunized GALT/KO mice as recipients of GAL+ heart allografts. RESULTS: In young GALT/KO mice the levels of anti-GAL antibodies were low. Immunization of GALT/KO mice resulted in increased anti-GAL antibody expression. In mouse serum 0.6% of IgG was specific for alphaGAL compared to 0.5% in human serum. The avidity of purified mouse and human anti-GAL IgG was 30 and 6 nM, the affinity 15 and 50 microM, respectively. The isotype distribution in mouse and human anti-GAL IgG appeared to be similar to the isotype distribution in normal sera. The affinity of mouse and human anti-GAL IgM was 150 and 750 microM, respectively. Immunized GALT/KO recipients of GAL+ heart transplants rejected their grafts within 2 hr although nonimmunized GALT/KO mice retained their grafts for up to 6 days. Immunohistological examination of the rejected GAL+ hearts revealed massive deposition of IgM and IgG on endothelial cells of the graft with a concomitant deposition of complement. CONCLUSIONS: Our studies demonstrate that anti-GAL antibodies from immunized GALT/KO mice bind alphaGAL with an avidity/affinity similar to human anti-GAL antibodies and are able to induce hyperacute rejection of GAL+ heart allografts.

Animals↗
PubMed2000

Inhibition of tumor necrosis factor mRNA translation by a rationally designed immunomodulatory peptide.

Based on sequences of immunomodulatory peptides derived from the heavy chain of HLA Class I, novel immunomodulatory peptides with increased potency were developed by computer-aided rational design. Allotrap 1258 was characterized in detail and shown to inhibit cell-mediated immune responses in vitro and in vivo. Immunomodulatory activity was associated with the capability of the peptides to modulate heme oxygenase (HO) activity. In this study we analyzed the effect of Allotrap 1258 on cytokine expression. Allotrap 1258 inhibited concanavalin A- and lipopolysaccharide-induced human and mouse tumor necrosis factor (TNF) production in vitro and in vivo but had no effect on interleukin (IL)-1, IL-2, IL-4, IL-6, or IL-10 expression. Experiments with HO-1/KO and iNOS/KO mice showed that Allotrap 1258-mediated inhibition of TNF was independent of HO-1 and iNOS. Quantitation of TNF protein expression and mRNA steady state levels demonstrated that Allotrap 1258-mediated inhibition occurred at the translational level. Deletion of the AU-rich element in the 3'-untranslated region (UTR) of TNF mRNA, a region known to be involved in TNF mRNA translation, had minimal effect on Allotrap 1258-mediated inhibition. However, replacement of the TNF 3'-UTR with the human globin 3'-UTR rendered the peptide inactive. This demonstrates that besides AU-rich elements, other sequences in the 3'-UTR of TNF mRNA are involved in translational control of TNF expression. Such sequences are necessary for Allotrap 1258-mediated inhibition of TNF production.

3' Untranslated Regions↗
PubMed2000

Alleviation of graft-versus-host disease after conditioning with cobalt-protoporphyrin, an inducer of heme oxygenase-1.

BACKGROUND: Recently, we demonstrated that elevated expression of heme oxygenase-1 (HO-1 or Hsp-32) resulted in the modulation of several immune effector functions. Here we evaluated whether induction of HO-1 after administration of cobalt protoporphyrin (CoPP) can prevent the development of acute graft-versus-host-disease (GVHD). METHODS: Acute GVHD was initiated by injection of unfractionated spleen cells from C57BL/6 into B6D2/F1 mice. RESULTS: Administration of CoPP resulted in increased survival: 85% of CoPP-treated animals survived for >100 days compared with only 29% of saline-treated control animals (P<0.05). In contrast, administration of ZnPP, a well-known inhibitor of HO, accelerated GVHD development. The protective effect of CoPP therapy seemed to be caused by immunomodulation of donor cells, because treatment of cell donors prevented development of acute GVHD in 80% of recipients compared with 0% in control animals. Spontaneous lymphocyte proliferation could be measured with splenocytes harvested from animals developing GVHD but not with splenocytes from recipients of CoPP-treated donor cells. CoPP-treatment had no effect on interleukin-2 or interleukin-4 synthesis but inhibited interferon-gamma production. Mice with active GVHD demonstrated a defective lympho-proliferative response to alloantigens or concanavalin A. However, spleen cells isolated from survivors (on day 100) responded normally. Flow cytometric analysis of splenic T cell populations revealed a severe reduction in recipient type (H-2b,d) cells in mice with active GVHD, whereas in protected mice the number of cells remained normal. CONCLUSION: The results from this study confirmed our previous observation that up-regulation of HO-1 activity is associated with down-regulation of several immune effector functions. This resulted in protection from acute GVHD in a parent into F1 mouse model.

Animals↗
PubMed2000

Blocking of CD44-hyaluronic acid interaction prolongs rat allograft survival.

BACKGROUND: Lymphocyte activation and infiltration into a transplanted organ is an integral component of the rejection process. Graft infiltration of lymphocytes requires adhesion of leukocytes to the endothelium, diapedesis, and transmigration. One of several proteins involved in this process is CD44, which is known to interact with endothelial hyaluronan (HA). Blockade of cell-matrix and cell-cell interactions have been used extensively for modulation of immune responses and graft rejection. Based on these observations, we evaluated the effects of blocking CD44-HA interactions in a transplantation model. METHODS: We used a low molecular weight hyaluronic acid formulation (LMWHA) for the treatment of rat renal and cardiac allograft recipients. LMWHA was administered intraperitoneally at 0.5-5 mg/kg for 5-10 days after transplantation with or without a subtherapeutic dose of cyclosporine. RESULTS: LMWHA monotherapy prolonged allograft survival significantly, but only for a few days. In combination with low-dose cyclosporine, long-term survival of allografts was observed in some of recipients. CONCLUSION: Further definition of the underlying mechanism of LMWHA therapy may provide a rationale for the development of novel, nontoxic, nonimmunogenic immunotherapies.

Animals↗
PubMed2000

Gene transfer of immunomodulatory peptides correlates with heme oxygenase-1 induction and enhanced allograft survival.

BACKGROUND: Decapeptides derived from human HLA class I sequences have been shown to prolong allograft survival. The mechanism of action of these peptides has been uncertain, because they act in an MHC unrestricted manner. Recently, it was found that these peptides bind heme oxygenase 1 (HO-1). In the present study, we sought to determine whether local delivery of these peptides through gene transfer could extend allograft survival, and to explore the underlying mechanisms. METHODS: C57BL/6 neonatal hearts were transplanted to CBA/J recipients and the peptide, or plasmid DNA encoding the peptide, was injected directly into the allograft at the time of the transplant. RESULTS: Direct injection of 1 microg of the B2702 peptide into the allograft did not prolong survival (13.3+/-0.8 vs. 13.4+/-0.8 days for untreated controls), but injection of 400 microg of peptide did extend survival (22.0+/-0.6). Injection of plasmid DNA encoding the B2702 peptide was superior to peptide delivery, extending graft survival to 30.8+/-1.5 days. Similar results were obtained using another plasmid encoding the rationally designed peptide BC1 (28.5+/-1.7), whereas no significant prolongation was observed using a plasmid encoding the control peptide B2705 (16.5+/-1.0). To explore the hypothesis that these peptides exert their immunosuppressive effect by altering HO-1 activity, animals were treated with iron protoporphyrin, an inducer of HO-1 activity, or tin protoporphyrin, an inhibitor of HO-1. Treatment with iron protoporphyrin alone extended graft survival (24.5+/-1.6) and did not alter the benefit in survival seen with BC1 gene transfer (28.0+/-0.8). In contrast, treatment with tin protoporphyrin abolished the benefit of BC1 gene transfer (17.0+/-0.6). CONCLUSIONS: These results demonstrate that plasmid mediated gene transfer is an effective means for delivering immunosuppressive peptides to extend allograft survival. The experiments suggest that these peptides may act by increasing HO-1 activity and support a role for HO-1 in immune regulation and allograft survival.

Animals↗