A Signature of Maternal Anti-Fetal Rejection in Spontaneous Preterm Birth: Chronic Chorioamnionitis, Anti-Human Leukocyte Antigen Antibodies, and C4d

Chronic chorioamnionitis is found in more than one-third of spontaneous preterm births. Chronic chorioamnionitis and villitis of unknown etiology represent maternal anti-fetal cellular rejection. Antibody-mediated rejection is another type of transplantation rejection. We investigated whether there was evidence for antibody-mediated rejection against the fetus in spontaneous preterm birth.This cross-sectional study included women with (1) normal pregnancy and term delivery (n = 140) and (2) spontaneous preterm delivery (n = 140). We analyzed maternal and fetal sera for panel-reactive anti-HLA class I and class II antibodies, and determined C4d deposition on umbilical vein endothelium by immunohistochemistry. Maternal anti-HLA class I seropositivity in spontaneous preterm births was higher than in normal term births (48.6% vs. 32.1%, p = 0.005). Chronic chorioamnionitis was associated with a higher maternal anti-HLA class I seropositivity (p<0.01), significant in preterm and term birth. Villitis of unknown etiology was associated with increased maternal and fetal anti-HLA class I and II seropositivity (p<0.05, for each). Fetal anti-HLA seropositivity was closely related to maternal anti-HLA seropositivity in both groups (p<0.01, for each). C4d deposition on umbilical vein endothelium was more frequent in preterm labor than term labor (77.1% vs. 11.4%, p<0.001). Logistic regression analysis revealed that chronic chorioamnionitis (OR = 6.10, 95% CI 1.29–28.83), maternal anti-HLA class I seropositivity (OR = 5.90, 95% CI 1.60–21.83), and C4d deposition on umbilical vein endothelium (OR = 36.19, 95% CI 11.42–114.66) were associated with preterm labor and delivery.A major subset of spontaneous preterm births has a signature of maternal anti-fetal cellular and antibody-mediated rejections with links to fetal graft-versus-host disease and alloimmune reactions

Identification of the nonclassical HLA molecules, mica, as targets for humoral immunity associated with irreversible rejection of kidney allografts.

BACKGROUND: A substantial portion of kidney allografted patients experience early acute rejection episodes and even irreversible rejections in the early posttransplantation period. The presence of HLA alloantibodies before grafting is associated with early immunological complications, but in many patients rejections and graft loss occur even in the absence of such antibodies. METHODS: In this study, 748 serum samples taken before and at various time points after kidney transplantation from 139 patients were investigated for the presence, frequency, and specificity of kidney microvascular endothelial cell (KMEC)-reactive antibodies using major histocompatability class (MHC) I-related chain A (MICA) transfected cells and flow cytometry, antibody blocking experiments, and Western blotting. The ability of MICA-specific antibodies to fix complement and to induce a prothrombotic phenotype in KMECs was investigated. RESULTS: A polymorphic, 62 kDa nonclassical HLA class I molecule is identified as a new target molecule for reactivity in sera from patients with irreversible rejections. Specific blocking and transfection experiments verified the target molecule as MICA. A significant correlation was established for pre- or posttransplantation MICA humoral immunity and graft loss (P&lt;0.001). MICA-specific antibody titers increased in the posttransplantation period and were present before any signs of clinical rejection. MICA antibody-containing patient sera induced a prothrombotic phenotype in KMECs. CONCLUSION: The increasing polymorphism detected at the MIC loci combined with the results of this study suggest that typing for the MIC loci and crossmatching for the detection of anti-MIC antibodies before transplantation should be used routinely. A better recipient-donor selection based on a negative crossmatch for both anti-donor HLA and MICA antibodies will decrease early graft rejections and losses

Activated porcine embryonic brain endothelial cells induce a proliferative human T-lymphocyte response

Transplantation of allogeneic embryonic neural tissue is a potential treatment for patients with Parkinson's and Huntington's diseases. The supply of human donor tissue is limited, and alternatives such as the use of animal (e.g., porcine) donor tissue are currently being evaluated. Before porcine grafts can be used clinically, strategies to prevent neural xenograft rejection must be developed. Knowledge on how human T lymphocytes recognize porcine embryonic neural tissue would facilitate the development of such strategies. To investigate the ability of porcine embryonic brain microvascular endothelial cells (PBMEC) to stimulate human T-cell proliferation, PBMEC were immuno-magnetically isolated and cocultured with purified human CD4 or CD8 single-positive T cells. PBMEC had a cobblestone-like growth pattern and expressed the endothelial cell markers CD31 and CD106. PBMEC stimulated with the supernatant of phytohemagglutinin-activated porcine peripheral blood mononuclear cells or porcine IFN-gamma, but not nonstimulated PBMEC, induced proliferation of both CD8 and CD4 T cells as assessed by [H-3]thymidine incorporation. Flow cytometric analyses showed that the degree of CD8 and CD4 T cell proliferation correlated with the expression levels of class I and 11 major histocompatibility complex (MHC) antigens, respectively. PBMEC expressed a CTLA-4/Fc-reactive molecule, most likely CD86, suggesting that these cells are able to deliver a costimulatory signal to the T cells. Human TNF-alpha, but not human IFN-gamma, induced class I, but not class II, MHC expression on PBMEC. Within a neural graft or the regional lymph nodes, PBMEC might stimulate human T cells via the direct pathway, and should therefore be removed from the donor tissue prior to transplantation

Human natural antibodies cytotoxic to pig embryonic brain cells recognize novel non-Galalpha1,3Gal-based xenoantigens

Transplantation of porcine embryonic brain cells, including dopaminergic neurons, from ventral mesencephalon (VM) is considered a potential treatment for patients with Parkinson's disease. In the present study, we characterized the distribution among VM cells of the major porcine endothelial xenoantigen, the Galalpha1,3Gal epitope, and evaluated the cytotoxic effect of anti-Galalpha1,3Gal antibody-depleted and nondepleted human AB serum on VM cells. Overall levels of Galalpha1,3Gal-epitope expression was very low on the VM cell population using Bandeiraea simplicifolia IB(4) lectin staining of resuspended VM cells in flow cytometric analyses or staining of SDS-PAGE-separated, solubilized VM cell membrane proteins in Western blot analyses. Lectin-histochemical staining of sections of pig embryonal VM regions with BSA IB(4) lectin showed staining restricted to endothelial cells and microglia. In the presence of complement, both nondepleted and anti-Galalpha1,3Gal antibody-depleted AB sera were shown to be cytotoxic to VM cells as assessed in microcytotoxicity- and flow cytometry-based cytotoxicity assays. Purified IgM and IgG were both cytotoxic in the presence of complement. Three major VM cell membrane antigens of approximately 210, 105, and 50 kDa were reactive with natural IgM antibodies present in pooled human AB sera. Thus, antibody-dependent cytotoxicity may contribute to pig to human brain cell xenorejection, necessitating donor tissue modifications prior to a more widespread utilization of neural tissue xenografting

Cold-perfusion decellularization of whole-organ porcine pancreas supports human fetal pancreatic cell attachment and expression of endocrine and exocrine markers

Despite progress in the field of decellularization and recellularization, the outcome for pancreas has not been adequate. This might be due to the challenging dual nature of pancreas with both endocrine and exocrine tissues. We aimed to develop a novel and efficient cold-perfusion method for decellularization of porcine pancreas and recellularize acellular scaffolds with human fetal pancreatic stem cells. Decellularization of whole porcine pancreas at 4°C with sodium deoxycholate, Triton X-100 and DNase efficiently removed cellular material, while preserving the extracellular matrix structure. Furthermore, recellularization of acellular pieces with human fetal pancreatic stem cells for 14 days showed attached and proliferating cells. Both endocrine (C-peptide and PDX1) and exocrine (glucagon and α-amylase) markers were expressed in recellularized tissues. Thus, cold-perfusion can successfully decellularize porcine pancreas, which when recellularized with human fetal pancreatic stem cells shows relevant endocrine and exocrine phenotypes. Decellularized pancreas is a promising biomaterial and might translate to clinical relevance for treatment of diabetes