Lithium stimulates proliferation in cultured thyrocytes by activating Wnt/beta-catenin signalling

BACKGROUND

Lithium, clinically used in the treatment of bipolar disorders, is well known to induce thyroid growth. However, the mechanism involved is only incompletely characterized. Although it is conventionally believed that thyroid proliferation depends on the thyroid-stimulating hormone (TSH)/cAMP/cAMP response element binding protein (CREB) pathway, recent data indicate that Wnt/beta-catenin signalling may be of critical importance. In other cell types lithium activates canonical Wnt signalling by GSK-3beta inhibition, which in turn stabilizes cytosolic free beta-catenin. Here we investigated the potential modulation of Wnt/beta-catenin signalling under lithium treatment in primary and neoplastic human thyrocytes.

METHODS

Primary (S18) and neoplastic (NPA, FTC133) thyrocytes treated with and without LiCl were analysed using Western blotting, immunoprecipitation, reporter-gene assay, MTT proliferation assay and transfection studies.

RESULTS

LiCl dose-dependently inhibited GSK-3beta, stabilized free beta-catenin and inhibited beta-catenin degradation. Furthermore, LiCl altered the assembly of adherens junction by upregulating the E-cad-herin repressor, Snail, and downregulated E-cadherin expression. At a dose of 5 mM, LiCl significantly increased the proliferative potency of thyrocytes, which appeared to be mediated by beta-catenin, since nuclear beta-catenin stimulated T-cell factor/lymphoid enhancer factor (TCF/LEF)-mediated transcription and upregulated downstream targets like cyclin D1. To characterize the specificity of Wnt/beta-catenin-driven thyrocyte proliferation, we transfected primary thyrocytes and FTC133 cells with dominant negative TCF4 to block Wnt-dependent pathways or with dominant negative CREB to inhibit the TSH/cAMP cascade. In cells transfected with dominant negative CREB lithium-stimulated proliferation was unchanged whereas blocking Wnt/beta-catenin by dominant negative TCF4 reduced proliferation by approx. 50%.

CONCLUSION

Our data indicate that Wnt/beta-catenin signalling is of major importance in the control of lithium-dependent thyrocyte proliferation.

Wnt-5a has tumor suppressor activity in thyroid carcinoma

Stabilization of beta-catenin by inhibition of its phosphorylation is characteristic of an activation of the canonical Wnt/beta-catenin signaling pathway and is associated with various human carcinomas. It contrasts to an as yet incompletely characterized action of an alternative noncanonical Wnt signaling pathway on neoplastic transformation. The aim of the present study was to test the effects of a member of the noncanonical Wnt signaling pathway, Wnt-5a, in primary thyroid carcinomas and in thyroid carcinoma cell lines. Compared to normal tissue Wnt-5a mRNA expression was clearly increased in thyroid carcinomas. Immunohistochemically, a bell-shaped response was observed with low to undetectable levels in normal tissue and in anaplastic tumors whereas differentiated thyroid carcinomas showed strong positive immunostaining for Wnt-5a. Transfection of Wnt-5a in a thyroid tumor cell line FTC-133 was able to reduce proliferation, migration, invasiveness and clonogenicity in these cells. These effects of Wnt-5a are associated with membranous beta-catenin translocation and c-myc oncogene suppression and are mediated through an increase in intracellular Ca(2+) release, which via CaMKII pathways promotes beta-catenin phosphorylation. Specific inhibition of beta-catenin phosphorylation by W-7, a calmodulin inhibitor, or by KN-93, a CaMKII inhibitor, supports these findings whereas PKC inhibitors were without effect. This interaction occurs downstream of GSK-3 beta as no Wnt-5a effect was seen on the Ser(9) phosphorylation of GSK-3 beta. Our data are compatible with the hypothesis that Wnt-5a serves as an antagonist to the canonical Wnt-signaling pathway with tumor suppressor activity in differentiated thyroid carcinomas.

Porcine cell microchimerism but lack of productive porcine endogenous retrovirus (PERV) infection in naive and humanized SCID-beige mice treated with porcine peripheral blood mononuclear cells

Pigs are considered a suitable source of cells and organs for xenotransplantation. All known strains of pigs contain porcine endogenous retrovirus (PERV) and PERV released by porcine cells may infect human cells in vitro and severe-combined immunodeficient (SCID) mice in vivo. Humanized SCID (hu-SCID) mice develop immune response to porcine antigens. Here we investigated PERV transmission in humanized SCID-beige mice using porcine peripheral blood mononuclear cells (PBMC) as the donor tissue (and the source of PERV). Mice were infused in the peritoneal cavity with 1.5-3.0 x 10(7) unfractionated human PBMC. Unfractionated porcine PBMC (1.5-3.0 x 10(7) cell/mouse) were infused to the mice simultaneously with human PBMC or 3 weeks after human PBMC infusion. The treated mice were monitored for weight and skin changes, donor cell chimerism, anti-pig antibodies and PERV transmission. All humanized mice tested 5-12 weeks after human PBMC transplantation were macrochimeric (up to 40% of cells in blood) for human cells, where 99% of the human cells were T-lymphocytes. Although human B lymphocytes were very rare in the blood of humanized mice at that point, the mice were positive for human anti-pig natural antibodies. The control SCID-beige mice or mice treated with porcine PBMC alone were negative for anti-porcine antibodies. Approximately 70% of the humanized mice treated with porcine PBMC were also microchimeric for porcine cells. Although some tissue samples of these mice were positive for PERV DNA in the absence of porcine DNA indicating PERV infection, the infection was non-productive as PERV transcripts were not detectable in those tissues. PERV infection of human and mouse cells in vitro by co-culturing with porcine PBMC was also non-productive. Humanized SCID-beige mice suffered weight loss and occasional minor skin changes due to graft vs. host disease caused by human PBMC but none of the mice showed observable effect attributable to the apparent PERV infection alone.

Optimal size selection of laryngeal mask airway in Malaysian female adult population

BACKGROUND

The summary of various studies done looking at size selection of the laryngeal mask airway (LMA) in adults is that, selection based on sex is appropriate, and that both sizes 4 or 5 are adequate for adult females. However, in our local population these sizes may be too large especially the size 5 for adult females.

OBJECTIVE

To determine the optimal size of LMA in Malaysian female adults.

METHOD

135 ASA 1 or 2 adult female patients coming for elective surgery, requiring general anaesthesia suitable for LMA insertion were randomised into 3 groups to receive either a size 3, 4 or 5 LMA. Optimal size of the LMA was assessed based on 4 parameters, the number of attempts at placement, the oropharyngeal leak pressure (OLP), fibre optic score and the percentage of the vocal cords seen.

RESULTS

The 3 groups were demographically similar. There was no difference in the 3 groups in terms of number of attempts of placement, OLP and fibre-optic score. The percentage of vocal cords seen with the size 3 LMA was significantly less than for the size 4 and size 5 (p = 0.009). For the size 5 LMA group in 10/45 patients, the size 5 LMA was too big making it incorrectly positioned after successful insertion and in another 3/45 patients it was difficult to pass the size 5 LMA past the open mouth during insertion. There were no such problems with the size 3 or 4 LMA groups.

CONCLUSION

The optimal size of LMA for the female Malaysian adult is size 4.

Attenuation of aortic graft arteriosclerosis by systemic administration of Allotrap peptide RDP58

There remains no treatment for chronic allograft rejection mainly manifested by progressive arteriosclerosis. We investigated the effect of Allotrap peptide RDP58 therapy on arteriosclerosis in an aortic allotransplant model. RDP58 was administered intraperitoneally at 0.1, 0.5, or 2.5 mg/kg, every other day after transplantation. RDP58 therapy markedly inhibited vascular intimal thickening, media necrosis, and adventitial cellular inflammation. The attenuation of arteriosclerosis was associated with the induction of heme oxygenase (HO)-1 expression, inhibition of TNF-alpha production in aortic allografts, as well as decreased specific complement-dependent cytotoxic antibodies in serum. RDP58 inhibited both smooth muscle cell (SMC) proliferation with an 80% inhibition at 100 microM without evidence of cytotoxicity and TNF-induced apoptosis of SMCs in a dose-dependent fashion. These data suggest that the suppressive effect of RDP58 on allograft arteriosclerosis is due to multiple actions of the peptide, including induction of HO-1, inhibition of TNF-alpha, and a direct effect on SMC proliferation.

Ex vivo priming of naïve T cells into EBV-specific Th1/Tc1 effector cells by mature autologous DC loaded with apoptotic/necrotic LCL

Posttransplant lymphoproliferative disorders (PTLDs) represent life-threatening complications of bone marrow and solid organ transplantation (SOTx). These are B-cell malignancies triggered by Epstein-Barr Virus (EBV) infection in chronically immunosuppressed (IS) recipients. Immunosuppressed EBV seronegative (EBV(-)) organ recipients are at highest risk of developing PTLD owing to the lack of anti-EBV memory T cells to control subsequent EBV challenges. Our aim is to establish effective anti-EBV T-cell generation protocols for prevention or treatment of PTLD encountered in SOTx. We have used autologous dendritic cells (DCs) loaded with apoptotic/necrotic lymphoblastoid cell lines (LCLs) to evaluate the ability of such an approach to activate naïve T cells in vitro. In EBV(-) individuals, both CD8+ and CD4+ T-cell responses were amplified by this approach, as detected by IFN-gamma ELISPOT and cytotoxicity assays. The CD8+ T cells were poly-specific anti-EBNA3 A, -LMP2 and -BMLF1, with uniform reversion to a CD45RO+/RA-phenotype, decreased CD62L expression, and up-regulation of the activation markers CD28 and CD69. Addition of rhIL-12 improved anti-viral T-cell responses and reduced the functional differences observed between EBV(+) and EBV(-) responders. In conclusion, the DC/LCL method promotes cross-presentation of EBV-associated epitopes and may serve as an effective protocol for the adoptive immunotherapy of PTLD in EBV(-) SOTx patients.

Audit on tracheostomies performed at the General Intensive Care Unit, Kuala Lumpur Hospital

During a 6-month period from October 2000 to March 2001, we analysed the indications, methods, waiting period and complications following a tracheostomy at the General Intensive Care Unit (GIGU) of Hospital Kuala Lumpur. There were 49 tracheostomies performed during this period. Thirty of them were performed in the GICU using the percutaneous dilatational method while 19 were performed electively in the Operating Theatre (OT) by the ear, nose and throat (ENT) surgeons. The main indications for a tracheostomy were prolonged mechanical ventilation and airway protection for patients with a poor Glasgow Coma Scale. The average waiting time for a tracheostomy after a decision was made to perform one was 1.34 +/- 0.72 days for a percutaneous tracheostomy and 3.72 +/- 2.52 days for a surgical tracheostomy. This difference was statistically significant (p < 0.001). There was excessive bleeding in 3 patients in the percutaneous tracheostomy group and 1 patient in the surgical tracheostomy group. Percutaneous tracheostomy is now the main method of tracheostomy at the GICU in Hospital Kuala Lumpur. Haemorrhage is the most significant complication of this procedure. However the overall complication rate is comparable with that of a surgical tracheostomy.

Purification and characterization of a thermophilic and acidophilic chitinase from Microbispora sp. V2

AIM

Purification and characterization of a chitinase from Microbispora sp. V2.

METHODS AND RESULTS

The chitinase from Microbispora sp. V2 was purified to homogeneity by gel filtration chromatography with 4.6% recovery. It had a molecular weight of 35 kDa and showed maximum activity towards p-nitrophenyl-beta-d-N,N'-diacetylchitobiose, indicating a chitobiosidase activity. The enzyme had a pH optimum of 3.0 and temperature optimum of 60 degrees C. It was stable in a wide pH range from 3.0 to 11.0, retaining 61% activity at pH 3.0 and 52% activity at pH 11.0. It retained 71% activity at 30 degrees C and 45% activity at 50 degrees C, up to 24 h. The enzyme activity was not inhibited by any of the metal ions tested except Hg2+, in the presence of which only 10% activity was retained.

CONCLUSIONS

The 35 kDa chitinase from Microbispora sp. V2 has an acidic pH optimum and a high temperature optimum. It is fairly stable and active, and degrades chitin efficiently, although the growth of the culture and enzyme production is slow.

SIGNIFICANCE AND IMPACT OF THE STUDY

This report is the first detailed study of a chitinase from Microbispora sp. V2, isolated from hot springs. The chitinase from Microbispora sp. V2 may have potential applications in the recycling of chitinous wastes, particularly due to its thermophilic and acidophilic character. Studies at molecular level may provide further insight on the chitinolytic system of Microbispora spp. with respect to the number and types of chitinases and their regulation.

Purification, crystallization and preliminary X-ray diffraction studies of recombinant class A non-specific acid phosphatase of Salmonella typhimurium

The phoN gene of Salmonella enterica sv. Typhimurium strain MD6001 was cloned in the multicopy plasmid pBluescript SK(-). The nucleotide sequence of the cloned gene differs from the corresponding S. typhimurium LT2 sequence at 23 residues, leading to 15 amino-acid differences, but was very close to the S. typhi phoN sequence (only three nucleotide and two amino-acid differences). The recombinant PhoN protein was purified to homogeneity. Two forms of crystals were harvested from a single crystallization condition. Diffraction intensity data were collected using a laboratory X-ray source to resolution limits of 2.5 and 2.8 A for crystals belonging to space group C2 and C222(1), respectively. Based on non-crystallographic symmetry, four monomers of PhoN are expected to be present in the asymmetric unit of the C2 unit cell. Two monomers of a biologically active dimer in the asymmetric unit of the C222(1) unit cell are expected from the Matthews coefficient.

Flt3-L augments the engraftment of donor-derived bone marrow cells when combined with sublethal irradiation and costimulatory (CD28/B7 and CD40/CD40L) blockade

T-cell costimulatory blockade as a constituent for recipient conditioning prior to bone marrow transplantation has led to the development of less toxic protocols for the establishment of donor cell chimerism. We therefore hypothesized that the addition of the hematopoietic growth factor, Flt3-ligand (Flt3-L), to the perioperative inhibition of the CD28/B7 and CD40/CD40 ligand costimulatory pathways would enhance the engraftment of allogeneic bone marrow. Recipient BALB/c ByJ (H-2(d), Mls(c), Vbeta6+/Vbeta8+ TCR) received a single sublethal dose of total body irradiation (300 rad) 6 h prior to transplantation IV with unfractionated donor CBA/J (H-2(k), Mls(d), Vbeta6-/Vbeta8+ TCR) bone marrow cells. CTLA4-Ig and/or MRI were administered at 500 microg IP on days 0, 2, 4, and 6 posttransplantation. Flt3-L was administered at 10 microg IP on days 0-6. Donor cell chimerism was determined on days 30-90 by flow cytometric analysis. Donor-specific tolerance was assessed by skin grafting. In vitro TCR cross-linking assays and flow cytometry were utilized to explore the deletion of donor-reactive T cells. Recipients receiving CTLA4-Ig and MRI engrafted allogeneic bone marrow cells in the peripheral blood (3/6; 50%) with chimerism being detected at 2-31%. Addition of Flt3-L to this preconditioning regimen enhanced the incidence of engraftment of donor bone marrow cells (10/13; 3-70%). Long-term survival of donor but not third-party-specific skin grafts demonstrated that donor-specific tolerance had been achieved in the chimeric recipients. Deletion of the donor-reactive T cells within the chimeric recipients was also observed. The addition of hematopoietic growth factors and cytokines to the nonmyeloablative regimen of sublethal irradiation and T-cell costimulatory blockade provides a novel strategy for the establishment of donor cell chimerism and for the induction of stable and robust donor-specific tolerance. The deletion of donor-reactive T cells using this protocol suggests the reliability and feasibility of this protocol for clinical transplantation.

Use of recombinase activation gene-2 deficient mice to ascertain the role of cellular and humoral immune responses in the development of chronic rejection

INTRODUCTION

Given its multifactorial etiology, the relative contribution of anti-donor cellular and humoral immune responses in the pathogenesis of chronic rejection is as yet ambiguous. We hypothesized that alloreactive T and B cells play a seminal role in the development of this lesion.

METHODS

To address this hypothesis, RAG-2(-/-) mice were used as donors and recipients in a well-established murine model of aortic transplantation. Grafts were transplanted across the following groups: Group I: C3H --> C3H; Group II: Wild-type [WT] 129Sv (H-2(b)) --> C3H (H-2(k)); Group III: C3H --> WT 129Sv; Group IV: 129SvEv RAG-2(-/-) --> C3H; and Group V: C3H --> 129SvEv RAG-2(-/-). Grafts were harvested at d40 to 146 post-transplantation for morphologic and immunohistochemical analyses and semi-quantitative RT-PCR was employed to evaluate the intragraft mRNA expression of various immune mediators. Mixed lymphocyte reaction and complement-mediated alloantibody cytotoxicity assays were performed to determine anti-donor proliferative and humoral responses, respectively.

RESULTS

Unlike that across the syngeneic combination (Group I), marked intimal thickening with corresponding luminal narrowing was observed in the majority of the aortic allografts (Groups II-IV). On the contrary, the morphology of C3H aortic allografts harvested from the majority of the RAG-2(-/-) was remarkably preserved. Correspondingly, anti-donor proliferative and humoral immune responses were undetectable in C3H --> RAG-2(-/-) recipients as was the intragraft mRNA expression of the Th(1) and the Th(2)-type cytokines.

CONCLUSIONS

Taken together, these data suggest that in this murine model of aortic allotransplantation, donor-specific cellular and humoral responses play a dominant role in the initiation and perpetuation of chronic rejection.

Clinical and laboratory evaluation of the safety of a bioartificial liver assist device for potential transmission of porcine endogenous retrovirus

BACKGROUND

The potential risk of transmission of porcine endogenous retroviruses (PERV) from xenogeneic donors into humans has been widely debated. Because we were involved in a phase I/II clinical trial using a bioartificial liver support system (BLSS), we proceeded to evaluate the biosafety of this device.

MATERIALS AND METHODS

The system being evaluated contains primary porcine hepatocytes freshly isolated from pathogen-free, purpose-raised herd. Isolated hepatocytes were installed in the shell, which is separated by a semipermeable membrane (100-kD nominal cutoff) from the lumen through which the patients' whole blood is circulated. Both before and at defined intervals posthemoperfusion, patients' blood was obtained for screening. Additionally, effluent collected from a clinical bioreactor was analyzed. The presence of viral particles was estimated by reverse transcriptase-polymerase chain reaction (RT-PCR) and RT assays. For the detection of pig genomic and mitochondrial DNA, sequence-specific PCR (SS-PCR) was used. Finally, the presence of infectious viral particles in the samples was ascertained by exposure to the PERV-susceptible human cell line HEK-293.

RESULTS

PERV transcripts, RT activity, and infectious PERV particles were not detected in the luminal effluent of a bioreactor. Culture supernatant from untreated control or mitogen-treated porcine hepatocytes (cleared of cellular debris) also failed to infect HEK-293 cell lines. Finally, RT-PCR, SS-PCR, and PERV-specific RT assay detected no PERV infection in the blood samples obtained from five study patients both before and at various times post-hemoperfusion.

CONCLUSION

Although longer patient follow-up is required and mandated to unequivocally establish the biosafety of this device and related bioartificial organ systems, these analyses support the conclusion that when used under standard operational conditions, the BLSS is safe.

Identification of the CD32/FcgammaRIIc-Q13/STP13 polymorphism using an allele-specific restriction enzyme digestion assay

We have recently reported that in addition to FcgammaRIIIa (CD16), approximately 45% of normal individuals also express FcgammaRIIc (CD32) on their natural killer (NK) cells. We found this expression to be regulated by an allelic polymorphism localized in the first extracellular exon (EC1) of the FcgammaRIIC gene, corresponding to aa 13. This is determined by a single nucleotide substitution, which results in either a functional open reading frame (glutamine-Q) or a premature stop codon (STP). Identification of this polymorphism provided a good explanation for the lack of CD32 expression previously observed with NK cells in some normal individuals. Here, we describe a new method for detection of FcgammaRIIc allelism based on RT-PCR amplification followed by an allele-specific restriction enzyme digestion. This method is rapid, reliable and time saving, as compared to the currently available allele-specific oligo-nucleotide probe-based Southern Blotting.

Crop residue addition effects on myriad forms and sorption of phosphorus in a Vertisol

Crop residues are a vital organic resource and their extensive use in soil management for sustainable agriculture is widely advocated. The effects of soybean residue (SR) and wheat residue (WR) applied alone or in combination with fertilizer P (FP) on dynamics of labile P, distribution of P fractions and P sorption in a Vertisol (Typic Haplustert) were assessed in a 16 week long incubation study. The amount of P added through crop residues, FP or their combination was kept constant at 10 mg P kg(-1) soil. Addition of SR or WR resulted in net increase of labile inorganic (Pi) and organic (Po) P, and microbial P throughout the incubation period, except that the WR decreased labile Pi during the first two weeks due to Pi immobilization. Integration of FP with SR had no added benefit compared to SR alone, while use of FP + WR proved better in ensuring short-term P availability by offsetting initial P immobilization associated with WR alone. Sequential fractionation of soil P at the end of 16 weeks showed that addition of SR and WR alone or in combination with FP favoured a build-up in labile Pi and Po (NaHCO3-Pi and Po), and moderately labile Po (NaOH-Po) fractions at the expense of recalcitrant P (HCl-P). The P sorption capacity of soil and P required to maintain optimum solution P concentration of 0.2 mg P 1(-1) also decreased with addition of these crop residues. The implication of the results of this study is that soybean and wheat residues can potentially improve soil P fertility by increasing labile Pi and Po, and moderately labile Po fractions, decreasing P sorption and concomitantly causing dissolution of recalcitrant P in soil.

Heavy metals concentrations in the sediments from Kolleru Lake, India

Kolleru Lake is the largest natural freshwater lake of Andhra Pradesh in India. It is situated between the latitudes 16 degrees 32(1) and 16 degrees 47(1)N and longitude 81 degrees 05(1) and 81 degrees 21(1) E. The catchment area of the lake is 4763 sq. km. The sediment samples were collected at different points from Kolleru Lake in three seasons a year over a period of three years and analyzed for heavy metals and organic matter. Concentrations of Cu, Pd, Cd, Mn, Ni, Co, Fe and Zn in the sediments were analysed by using Atomic absorption spectrometer (AAS) and selected sediments samples were analysed for Be, Sr, Ba, B, Mo, Tl, V, Cr, Ag, Bi, As and Se by using inductively coupled plasma Mass Spectrometer (ICP-MS).

Quantitation of immunosuppression by tacrolimus using flow cytometric analysis of interleukin-2 and interferon-gamma inhibition in CD8(-) and CD8(+) peripheral blood T cells

The authors have determined the frequency of intracellular interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) synthesis by T-cell subsets in whole blood (WB) and isolated lymphocytes in 16 transplant recipients treated with tacrolimus and 10 control patients who were not transplant recipients. The authors also determined the impact of varying amounts of red blood cells (RBC) on immunosuppression by tacrolimus. Samples were analyzed by two-color flow cytometry, and the results were expressed as a ratio of whole blood to isolated lymphocytes. In healthy subjects who were not transplant recipients, the frequency of IL-2--producing CD8(-) and CD8(+) cells was higher in WB than in isolated lymphocytes (mean +/- SD of whole blood to lymphocytes ratio: 1.24 +/- 0.5 and 1.67 +/- 0.62, respectively). Adding varying amounts of RBC had no significant impact on IL-2 production by CD8(-) and CD8(+) T cells. Adding tacrolimus (10 ng/mL) to lymphocyte cultures inhibited (90%) IL-2 production in isolated T cells but not in the whole-blood assay. The dose of tacrolimus required for a 50% inhibition of IL-2 release in T cells was 10-fold higher in cultures with RBC than without. Peripheral blood mononuclear cells (PBMC) isolated from tacrolimus-treated whole blood (WB) showed less IL-2 inhibition than did lymphocytes in the WB. The authors also tested cytokine production in WB and PBMCs in 16 transplant recipients and observed various patterns of reactivity. The frequency of IL-2--producing CD8(-) and CD8(+) cells was similar using two different methods in 10 of 16 patients tested. By contrast, in the remaining six patients the authors observed a significant inhibition of IL-2 production in both CD8(-) and CD8(+) T-cell subsets in the whole-blood assay but not in the isolated lymphocytes. The frequency of CD8(-) IFN-gamma--producing cells was significantly lower in 9 of 16 patients, but the same individuals showed no inhibition of their CD8(+) IFN-gamma T cells. The trough levels of tacrolimus did not predict the level of cytokine inhibition in the whole-blood assay in these patients. The authors' results show that the whole-blood assay for cytokine production can be used for monitoring the in vivo effect of tacrolimus in transplant recipients.

Interleukin-17 antagonism inhibits acute but not chronic vascular rejection

BACKGROUND

Blocking the action of interleukin (IL) 17 with an IL-17 receptor (R):Fc fusion protein inhibits T-cell proliferative responses to alloantigens and prolongs vascularized heart graft survival. In this study, we examined whether IL-17 antagonism could suppress the development of chronic rejection.

METHODS

A 0.6-cm section of C57BL10 (H2b) thoracic aorta was transplanted to recipient C3H (H2k) abdominal aorta. IL-17R:Fc or control human immunoglobulin G was administered i.p. (500 microg/day) from days 0 to 6 or from days 0 to 29. Mice were killed on days 7 or 30. Grafts were examined histologically and stained for alpha-smooth muscle actin (alpha-smA). Antidonor mixed leukocyte reaction, cytotoxic T cell, and alloantibody responses were quantified.

RESULTS

On day 7, control grafts showed mononuclear cell (MNC) infiltration, pronounced endothelial damage, and apoptosis of intimal and medial cell compartments. By day 30, there was concentric intimal thickening, accumulation of alpha-smA+ cells, and collagen deposition. Patchy destruction of the elastic membranes and loss of alpha-smA expression in media were evident. IL-17R:Fc for 6 days decreased MNC infiltration in the intimal and medial compartments at day 7. The endothelium was preserved (completely or partially) in all grafts. The medial compartment showed normal alpha-smA expression. Irrespective of IL-17R:Fc treatment for either 6 days or continuously, allografts harvested at day 30 showed circumferential intimal thickening, with accumulation of alpha-smA+ cells and collagen deposition. There was no effect on circulating alloantibody levels.

CONCLUSIONS

These findings support a role for IL-17 in the immunopathogenesis of acute vascular rejection and demonstrate the potential of IL-17 antagonism for therapy. By contrast, IL-17 antagonism does not appear to prevent ensuing chronic graft vascular disease, in particular neointimal formation.