Altered Storage and Function of von Willebrand Factor in Human Cardiac Microvascular Endothelial Cells Isolated from Recipient Transplant Hearts.

The assembly of von Willebrand factor (VWF) into ordered helical tubules within endothelial Weibel-Palade bodies (WPBs) is required for the efficient deployment of the protein at sites of vascular injury. VWF trafficking and storage are sensitive to cellular and environmental stresses that are associated with heart disease and heart failure. Altered storage of VWF manifests as a change in WPB morphology from a rod shape to a rounded shape and is associated with impaired VWF deployment during secretion.

Leukocyte Adhesion Under Hemodynamic Flow Conditions.

Vascular endothelial cells (ECs) line the luminal side of all blood vessels and act as a selective barrier between blood and tissue. ECs are constantly exposed to biochemical and biomechanical stimuli from the blood and underlying tissue. Fluid shear stress acts in parallel to the vessel wall, resulting from friction of blood against EC.

Role of anti-vimentin antibodies in renal transplantation.

Background: The role of non-HLA antibodies in rejection is not clear. We investigate whether antibodies to vimentin are made after renal transplantation and if production is associated with interstitial fibrosis and tubular atrophy (IFTA).

Methods: In this retrospective study, sera from 70 recipients of renal allografts (40 controls, 30 IFTA) were studied.

Pre-transplant donor HLA-specific antibodies: characteristics causing detrimental effects on survival after lung transplantation.

Background: The impact of Luminex-detected HLA antibodies on outcomes after lung transplantation is unclear. Herein we have undertaken a retrospective study of pre-transplant sera from 425 lung transplants performed between 1991 and 2003.

Methods: Pre-transplant sera, originally screened by complement-dependent cytotoxicity (CDC) assays, were retrospectively tested for the presence of HLA-specific antibodies using HLA-coated Luminex beads and C4d deposition on Luminex beads.

Heat shock protein-27 delays acute rejection after cardiac transplantation: an experimental model.

Background: Rejection is the major obstacle to survival after cardiac transplantation. We investigated whether overexpression of heat shock protein (Hsp)-27 in mouse hearts protects against acute rejection and the mechanisms of such protection.

Methods: Hearts from B10.

Role of anti-vimentin antibodies in allograft rejection.

Production of anti-vimentin antibodies (AVA) after solid organ transplantation are common. Although classically thought to be expressed mainly within the cytosol, recent evidence demonstrates that extracellular or cell surface expression of vimentin is not unusual. This review examines the evidence to assess whether AVA contribute to allograft pathology.

Solid phase assay measuring C4d deposition to determine complement fixation by HLA-specific antibodies.

The definition of HLA-specific antibodies in solid organ transplant patients is a necessary tool for recipient selection prior to transplantation and monitoring for rejection post transplant. Solid phase assays can detect both complement fixing and non-complement fixing HLA-specific antibodies. Here we describe a method for determining the presence of complement fixing HLA-specific antibodies using a sensitive solid phase assay.

Antibody alone is not a stimulator of exocytosis of Weibel-Palade bodies from human endothelial cells.

Background: The mechanisms of antibody-mediated damage to allografts are not well understood. We have examined the effect of antibodies to human leukocyte antigens on secretion of von Willebrand factor (vWF) from endothelial cells (ECs).

Methods: The effect of monoclonal antibodies (W6/32, L2, and L243), in the presence and absence of sublytic concentrations of complement, on the release of vWF from Weibel-Palade bodies (WPBs) in human umbilical vein ECs (HUVECs), human aortic ECs (HAECs), and human heart microvascular ECs (HHMECs) was investigated using biochemical and live-cell imaging.

The interplay between the Rab27A effectors Slp4-a and MyRIP controls hormone-evoked Weibel-Palade body exocytosis.

Weibel-Palade body (WPB) exocytosis underlies hormone-evoked VWF secretion from endothelial cells (ECs). We identify new endogenous components of the WPB: Rab3B, Rab3D, and the Rab27A/Rab3 effector Slp4-a (granuphilin), and determine their role in WPB exocytosis. We show that Rab3B, Rab3D, and Rab27A contribute to Slp4-a localization to WPBs.

Genetic or pharmaceutical blockade of phosphoinositide 3-kinase p110δ prevents chronic rejection of heart allografts.

Chronic rejection is the major cause of long-term heart allograft failure, characterized by tissue infiltration by recipient T cells with indirect allospecificity. Phosphoinositol-3-kinase p110δ is a key mediator of T cell receptor signaling, regulating both T cell activation and migration of primed T cells to non-lymphoid antigen-rich tissue. We investigated the effect of genetic or pharmacologic inactivation of PI3K p110δ on the development of chronic allograft rejection in a murine model in which HY-mismatched male hearts were transplanted into female recipients.

Late antibody-mediated rejection after heart transplantation following the development of de novo donor-specific human leukocyte antigen antibody.

Background: Antibody-mediated rejection (AMR) is an important problem after heart transplantation. Most cases seem to occur in sensitized recipients with preformed donor-specific human leukocyte antigen antibody (DSA) early after transplantation. Few data exist on AMR in patients who form de novo DSA.

Accommodation: does it apply to human leukocyte antigens?

The term "accommodation" was invoked to describe endothelial cell resistance to antibody-mediated rejection after ABO-incompatible kidney or experimental xenograft transplantation. Currently, there is much interest in how to achieve successful human leukocyte antigen (HLA)-incompatible allograft transplantation in HLA-sensitized patients and how to treat antibody-mediated rejection after ABO-compatible HLA-incompatible allotransplantation. The term "accommodation" is often used interchangeably to describe patients who have donor-specific ABO or HLA alloantibodies in the absence of damage to their allograft.

HLA and MICA: targets of antibody-mediated rejection in heart transplantation.

Background: The goal of this study was to determine whether antidonor antibodies directed against human leukocyte antigen (HLA) or endothelial cells (ECs) expressed antigens, including major histocompatibility complex class I chain-related antigens A (MICA) are associated with the diagnosis of antibody-mediated rejection (AMR) in heart transplant recipients.

Methods: We studied posttransplant antidonor HLA antibodies in 168 heart allograft recipients transplanted from October 2001 to December 2005. Among them, there were 37 AMR+ patients and 131 age- and sex- matched AMR- controls.

Report from a consensus conference on antibody-mediated rejection in heart transplantation.

Background: The problem of AMR remains unsolved because standardized schemes for diagnosis and treatment remains contentious. Therefore, a consensus conference was organized to discuss the current status of antibody-mediated rejection (AMR) in heart transplantation.

Methods: The conference included 83 participants (transplant cardiologists, surgeons, immunologists and pathologists) representing 67 heart transplant centers from North America, Europe, and Asia who all participated in smaller break-out sessions to discuss the various topics of AMR and attempt to achieve consensus.

The indirect alloimmune response causes microvascular endothelial dysfunction-a possible role for alloantibody.

Background: The causes of endothelial dysfunction after cardiac transplantation are unknown. Here, we have investigated whether the indirect alloimmune response mediates endothelial dysfunction in a major histocompatibility complex class I mismatch model.

Methods: PVG.

Protective effect of phosphorylated Hsp27 in coronary arteries through actin stabilization.

There is evidence for an inverse association between cellular expression of Hsp27 and vascular disease with carotid plaques, endarterectomy specimens, and cardiac biopsies investigated to date. Here we compare non-diseased coronary arteries from human heart transplant donors and patients with dilated cardiomyopathy (DCM) with no evidence of coronary artery disease, to coronary arteries from patients with ischemic heart disease (IHD) in order to determine abundance of phosphorylated Hsp27 (phospho-Hsp27) in plaque-free diseased vessels and elucidate how this protective effect is brought about through protein regulation. Western blotting identified phospho-Hsp27, phosphorylated on Ser82, Ser78, and Ser15, to be specifically decreased in IHD, but not DCM, compared to non-diseased vessels.

Autoimmunity to vimentin potentiates graft vasculopathy in murine cardiac allografts.

Background: There is increasing evidence for a role for autoimmunity in transplant rejection. It has previously been shown that autoantibodies to vimentin (Vim) accelerate acute rejection of murine cardiac allografts. We have investigated whether autoimmunity to Vim contributes to development of cardiac allograft vasculopathy (CAV).

Leucocyte adhesion under haemodynamic flow conditions.

Vascular endothelial cells (EC) line the luminal side of all blood vessels and act as a selective barrier between blood and tissue. EC are constantly exposed to biochemical and biomechanical stimuli from the blood and underlying tissue. Fluid shear stress acts in parallel to the vessel wall, resulting from friction of blood against EC.

Effect of phosphorylated hsp27 on proliferation of human endothelial and smooth muscle cells.

Recent studies have suggested a protective role of hsp27 against atherosclerosis and transplant graft vasculopathy. Here we have investigated the effects of over-expression of wild-type hsp27 and its phosphorylation mimics on proliferation of human endothelial cells (ECs) and smooth muscle cells (SMCs). ECs and SMCs cultured from human blood vessels or cells lines (human microvascular endothelial cell line and human telomerase reverse transcriptase subunit SMC) were infected with adenovirus containing DNA from wild-type hsp27, hyper-phosphorylated hsp27 mimic (3D hsp27), hypo-phosphorylated hsp27 mimic (3A hsp27) or anti-sense hsp27, and proliferation measured over the next 5 days.

Clinical relevance of complement-fixing antibodies in cardiac transplantation.

This paper includes a review of the relative importance of pretransplant complement-fixing and non-complementing-fixing human leukocyte antigen (HLA) and non-HLA antibodies (Abs). Sera from 565 adult cardiac transplant recipients were retrospectively analysed for the presence of HLA antibodies using complement-dependent cytotoxicity (CDC), HLA-coated Luminex beads, and C4d deposition on Luminex beads and results were correlated with graft survival. Of 565 patients, 14 had CDC-positive donor-specific Abs (DSA) before their transplant.

A reevaluation of the role of IgM Non-HLA antibodies in cardiac transplantation.

Background: Preexisting IgG antibodies to donor human leukocyte antigens (HLA) are a risk factor for rapid allograft rejection. However, non-HLA antibodies, of the IgM class, also called autoreactive antibodies, are not believed to affect graft survival. The aim of this study was to determine the incidence and clinical relevance of pretransplant lymphocytotoxic non-HLA IgM antibodies on long-term cardiac allograft survival.

Expression of endothelial intercellular adhesion molecule-1 is determined by genotype: effects on efficiency of leukocyte adhesion to human endothelial cells.

Two biallelic polymorphisms, previously described in the human intercellular adhesion molecule (ICAM)-1 gene at codon 241 (glycine [G] to arginine [R] substitution) and codon 469 (glutamic acid [E] to lysine [K] substitution) have been associated with a number of diseases including myocardial infarction, transplant rejection, and diabetes. However, the functional significance of these polymorphisms has not been determined. ICAM-1 cell surface expression and ICAM-1-mediated leukocyte adhesion were investigated using Cos7 transfected with ICAM-1 polymorphic variants or human umbilical vein endothelial cells (HUVEC) of different ICAM-1 genotypes.