Epidemic jaundice: Harvard's 5th General Hospital at Musgrave Park in World War II.
Explore the source record for details and available documents.
Disease Outbreaks↗
Biomedical subjects
J S Logan
Publications and source records attributed to J S Logan.
The structure of anti-Gal immunoglobulin genes in naïve and stimulated Gal knockout mice.
BACKGROUND: Naturally occurring antibodies (Nabs) that bind to terminal galactose alpha1,3-galactose carbohydrate structures (Gal) are present in humans and Old World monkeys but are negatively regulated in other mammalian species because they express Gal epitopes on their cell surfaces. A Gal knockout mouse (Gal-/-) model, generated by homologous disruption of alpha1,3-galactosyltransferase gene, is capable of producing natural anti-Gal Abs. METHODS: To study the genetic control of the anti-Gal response, we have generated anti-Gal hybridomas from Gal-/- mice and analyzed VH genes of anti-Gal Abs from naïve animals and from mice stimulated by rat heterotopic heart transplantation. RESULTS: Six immunoglobulin (Ig)M anti-Gal hybridomas derived from naïve Gal-/- mice exhibited anti-Gal binding activity with some cross-reactivity to related carbohydrate structures. These naïve anti-Gal Abs used five different VH genes in a germline configuration. Anti-Gal IgM hybridomas isolated after a rat heterotopic heart xenograft (4 days) utilized germline VH gene segments from the VH7183 family and exhibited less cross-reactivity. In contrast to mice 4 days after xenograft, we have predominantly isolated IgG anti-Gal hybridomas from mice 21 days after rat heterotopic heart xenografts, indicating an isotype switch. Nine of the IgG anti-Gal hybridomas secreted IgG3 subclass and one produced IgG1. Sequence analysis of the VH gene usage from the induced anti-Gal IgG antibodies demonstrated a restricted gene utilization (VHJ606-V14A). CONCLUSION: Our results demonstrate that the anti-Gal response in naïve Gal-/- mice is encoded by multiple germline progenitors. In response to a xenograft, the induced anti-Gal Abs exhibited a restricted gene usage and somatic mutations, indicating a positive selection.
Animals↗
A human CD46 transgenic pig model system for the study of discordant xenotransplantation.
BACKGROUND: The chronic shortage in the supply of human organs available for allotransplantation has turned attention toward the use of animals as potential donors, with pigs as the most likely species under consideration. Hyperacute rejection, the initial and immediate barrier to a pig-to-primate xenograft, has been addressed by generation of transgenic pigs that express the human membrane-bound complement-regulatory proteins CD59 and/or CD55. Difficulty has been encountered in generation of transgenic animals that express a third membrane-bound complement-regulatory protein, CD46. METHODS: We have generated transgenic animals by using a large genomic construct that encompasses the entire human CD46 gene. RESULTS: We report the first description of transgenic mice and pigs that express high levels of human CD46 in a cell and tissue type-specific manner, resembling patterns of endogenous CD46 expression observed in human tissues. Furthermore, when human CD46 transgenic porcine hearts were transplanted into baboons, the grafts did not succumb to hyperacute rejection, and survival extended for up to 23 days. Under the same conditions, nontransgenic grafts underwent hyperacute rejection within 90 min. CONCLUSIONS: This is the first report to describe generation of transgenic pigs that express human CD46, and the first in vivo demonstration of the ability of human CD46 expressed on pig organs to regulate complement activation and overcome hyperacute rejection upon transplantation of a vascularized organ into nonhuman primates.
Animals↗
The role of anti-Galalpha1-3Gal antibodies in acute vascular rejection and accommodation of xenografts.
BACKGROUND: A major impediment to the transplanting of porcine organs into humans is the susceptibility of porcine organs to acute vascular rejection, which can destroy a vascularized xenograft over a period of hours to days. Acute vascular rejection of porcine-to-primate xenografts is thought to be triggered by binding of xenoreactive antibodies to the graft. We tested whether antibodies, binding to Galalpha1-3Gal epitopes in porcine tissue, initiate this phenomenon. METHODS AND RESULTS: Specific depletion of anti-Galalpha1-3Gal antibodies from the blood of baboons, using extracorporeal perfusion of separated plasma through columns of Sepharose beads covalently linked to the antigenic trisaccharide, Galalpha1-3Galbeta1-4GlcAc, averted the development of acute vascular rejection in porcine organs transgenic for human decay-accelerating factor and CD59. More importantly, after immunodepletion was stopped and Gala1-3Gal antibodies were allowed to return, these same organs continued to function and remained pathologically normal and thus seemed to achieve a state of accommodation. CONCLUSION: These results demonstrate that anti-Galalpha1-3Gal antibodies cause acute vascular rejection and suggest that depletion of these antibodies leads to accommodation of the donor cardiac xenograft and could supply an important model for additional study.
Acute Disease↗
Prospects for xenotransplantation.
Pig-to-primate organ survival has been extended from a few minutes to weeks and occasionally months, following the development of transgenic pigs that express human complement-regulatory proteins, efficient antibody removal technologies and immunosuppressive strategies. The current limitation to the clinical application of this technology is acute vascular rejection, and an understanding of the mechanisms of this process and the development of modalities to overcome it are key to making significant progress at solving the critical shortage of organs for transplantation. Approaches that address this issue are underway in a number of laboratories.
Animals↗
Non-depleting anti-CD4, but not anti-CD8, antibody induces long-term survival of xenogeneic and allogeneic hearts in alpha1,3-galactosyltransferase knockout (GT-Ko) mice.
The anti-galactose-alpha1,3-galactose (Gal) antibody (Ab) response following pig-to-human transplantation is vigorous and largely resistant to currently available immunosuppression. The recent generation of GT-Ko mice provides a unique opportunity to study the immunological basis of xenograft-elicited anti-Gal Ab response in vivo, and to test the efficacy of various strategies at controlling this Ab response [1]. In this study, we compared the ability of non-depleting anti-CD4 and anti-CD8 to control rejection and antibody production in GT-Ko mice following xenograft and allograft transplantation. Hearts from baby Lewis rat or C3H mice were transplanted heterotopically into GT-Ko. Non-depleting anti-CD4 (YTS177) and anti-CD8 (YTS105) Abs were used at 1 mg/mouse, and given as four doses daily from day -2 to 1 then q.o.d. till day 21. Xenograft rejection occurred at 3 to 5 days post-transplantation in untreated GT-Ko recipients, and was histologically characterized as vascular rejection. Anti-CD4, but not anti-CD8, Ab treatment prolonged xenograft survival to 68 to 74 days and inhibited anti-Gal Ab as well as xeno-Ab production. In four of the five hearts from anti-CD4 mAbs-treated GT-Ko mice, we observed classic signs of chronic rejection, namely, thickened intima in the lumen of vessels, significant IgM deposition, fibrosis and modest mononuclear cell infiltrate of Mac-1+ macrophages and scattered T cells (CD8>CD4). Xenograft rejection in untreated, as well as anti-CD4- and anti-CD8-treated, recipients was associated with increased intragraft IL-6, IFN-gamma and IL-10 mRNA. C3H allografts were rejected in 7 to 9 days by untreated GT-Ko mice and were histologically characterized as cellular rejection. Treatment with anti-CD4 and anti-CD8 mAb resulted in graft survivals of >94.8 and 11.8 days, respectively. Anti-CD4 mAb treatment resulted in a transient inhibition of alloreactive and anti-Gal Ab production. The presence of circulating alloreactive and anti-Gal Abs at >50 days post-transplant was associated with significant IgM and IgG deposition in the graft. Yet, in the anti-CD4 mAb-treated group, the allografts showed no signs of rejection at the time of sacrifice (>100 days post-transplantation). All rejected allografts had elevated levels of intragraft IL-6, IFN-gamma and IL-10 mRNA, while the long-surviving anti-CD4-treated allografts had reduced mRNA levels of these cytokines. Collectively, our studies suggest that the elicited xeno-antibody production and anti-Gal Ab production in GT-Ko mice are CD4+ T-cell dependent. The majority of xenografts succumbed to chronic rejection, while allografts survived with minimal histological change, despite elevated levels of circulating alloAbs. Thus, immunosuppression with anti-CD4 mAb therapy induces long-term survival of allografts more effectively than to xenografts.
Animals↗
The role of antibodies in dysfunction of pig-to-baboon pulmonary transplants.
OBJECTIVE: Pulmonary transplantation has become the preferred treatment for end-stage lung disease, but application of the procedure is limited because of a paucity of donors. One way to solve donor limitations is to use animal organs as a donor source or xenotransplantation. The current barrier to pulmonary xenotransplantation is the rapid failure of the pulmonary xenograft. Although antibodies are known to play a role in heart and kidney xenograft rejection, their involvement in lung dysfunction is less defined. This project was designed to define the role of antibodies in pulmonary graft rejection in a pig-to-baboon model. METHODS: Orthotopic transgenic swine left lung transplants were performed in baboons depleted of antibodies by one of three techniques before transplantation: (1) ex vivo swine kidney perfusion, (2) total immunoglobulin-depleting column perfusion, and (3) ex vivo swine lung perfusion. Results were compared with those of transgenic swine lung transplants in unmodified baboons. RESULTS: All three techniques of antibody removal resulted in depletion of xenoreactive antibodies. Only pretransplantation lung perfusion improved pulmonary xenograft function compared with lung transplantation in unmodified baboons. CONCLUSIONS: The pathogenesis of pulmonary injury in a swine-to-primate transplant model is different from that in renal and cardiac xenografts. Depletion of antibodies alone does not have a beneficial effect and may actually be detrimental.
Animals↗
A strategic vision for telemedicine and medical informatics in space flight.
This Workshop was designed to assist in the ongoing development and application of telemedicine and medical informatics to support extended space flight. Participants included specialists in telemedicine and medical/health informatics (terrestrial and space) medicine from NASA, federal agencies, academic centers, and research and development institutions located in the United States and several other countries. The participants in the working groups developed vision statements, requirements, approaches, and recommendations pertaining to developing and implementing a strategy pertaining to telemedicine and medical informatics. Although some of the conclusions and recommendations reflect ongoing work at NASA, others provided new insight and direction that may require a reprioritization of current NASA efforts in telemedicine and medical informatics. This, however, was the goal of the Workshop. NASA is seeking other perspectives and views from leading practitioners in the fields of telemedicine and medical informatics to invigorate an essential and high-priority component of the International Space Station and future extended exploration missions. Subsequent workshops will further define and refine the general findings and recommendations achieved here. NASA's ultimate aim is to build a sound telemedicine and medical informatics operational system to provide the best medical care available for astronauts going to Mars and beyond.
Aerospace Medicine↗
CD46 transgene expression in pig peripheral blood mononuclear cells does not alter their susceptibility to measles virus or their capacity to downregulate endogenous and transgenic CD46.
CD46 (or membrane cofactor protein) protects autologous cells from complement-mediated lysis and has been expressed as a transgene in pigs to overcome complement-mediated hyperacute rejection of porcine organs upon transplantation into primates. Since CD46 has been identified as a receptor for measles virus (MV), the susceptibility of CD46-transgenic (tg) pig peripheral blood mononuclear cells (PBMC) to infection with MV strains which do and do not use CD46 as receptor was investigated. Surprisingly, it was found that MV vaccine strains (e.g. Edmonston) bound to tg as well as non-tg pig PBMC. Phytohaemagglutinin-stimulated CD46-tg and non-tg pig PBMC were equally well infected with MV vaccine strains irrespective of CD46 expression. Upon infection, tg CD46 was downregulated from the cell surface. In contrast, the binding capacity for MV wild-type strains to pig and human PBMC was low, irrespective of CD46 expression. These MV strains did not infect tg or non-tg pig cells. Expression of endogenous pig CD46 was detected with polyclonal sera against human CD46. After infection of pig PBMC with MV strain Edmonston, endogenous pig CD46 was also downregulated. This suggests an interaction between MV Edmonston and pig CD46. However, polyclonal CD46 sera did not inhibit infection with MV Edmonston indicating that CD46 may not exclusively act as a receptor for MV on these cells. Interestingly, similar results were observed using human PBMC. Data suggest that CD46 downregulation after interaction with MV may also occur in porcine organs which express endogenous and/or human CD46 as a means of protection against complement-mediated damage.
Animals↗
MondoA, a novel basic helix-loop-helix-leucine zipper transcriptional activator that constitutes a positive branch of a max-like network.
Max is a common dimerization partner for a family of transcription factors (Myc, Mad [or Mxi]), and Mnt [or Rox] proteins) that regulate cell growth, proliferation, and apoptosis. We recently characterized a novel Max-like protein, Mlx, which interacts with Mad1 and Mad4. Here we describe the cloning and functional characterization of a new family of basic helix-loop-helix-leucine zipper heterodimeric partners for Mlx termed the Mondo family. MondoA forms homodimers weakly and does not interact with Max or members of the Myc or Mad families. MondoA and Mlx associate in vivo, and surprisingly, they are localized primarily to the cytoplasm of cultured mammalian cells. Treatment of cells with the nuclear export inhibitor leptomycin B results in the nuclear accumulation of MondoA and Mlx, demonstrating that they shuttle between the cytoplasmic and nuclear compartments rather than having exclusively cytoplasmic localization. MondoA preferentially forms heterodimers with Mlx, and this heterocomplex can bind to, and activate transcription from, CACGTG E-boxes when targeted to the nucleus via a heterologous nuclear localization signal. The amino termini of the Mondo proteins are highly conserved among family members and contain separable and autonomous cytoplasmic localization and transcription activation domains. Therefore, Mlx can mediate transcriptional repression in conjunction with the Mad family and can mediate transcriptional activation via the Mondo family. We propose that Mlx, like Max, functions as the center of a transcription factor network.
Amino Acid Sequence↗
High level transcription of the complement regulatory protein CD59 requires an enhancer located in intron 1.
CD59 is a complement regulatory protein and may also act as a signal-transducing molecule. CD59 transgenic mice have been generated using a CD59 minigene (CD59 minigene-1). Although this minigene contained a 4.6-kilobase pair 5'-flanking region from the human CD59 gene as a promoter, the expression levels of the CD59 mRNA were substantially lower than those observed in humans, suggesting that CD59 gene expression might also require other transcriptional regulatory elements such as an enhancer. To investigate the transcriptional regulation of the CD59 gene, we used three cell lines that express CD59 at different levels. We have identified DNase I-hypersensitive sites in intron 1 in HeLa cells, which express CD59 at high levels, but not in Jurkat (intermediate level) or Raji cells (low level). Furthermore, cell line-specific enhancer activity was detected in a fragment containing these DNase I-hypersensitive sites. The CD59 enhancer was mapped to between -1155 and -888 upstream of the 5'-end of exon 2. To investigate the enhancer activity in vivo, a new CD59 minigene was constructed by the addition of the enhancer fragment into CD59 minigene-1. High expressor CD59 transgenic mice were generated using the new minigene.
Animals↗
Human complement regulatory proteins protect swine lungs from xenogeneic injury.
BACKGROUND: Pulmonary xenotransplantation is not possible because of hyperacute lung injury, the pathogenesis of which is unknown. This study evaluates complement-dependent pathways of pulmonary injury during heterologous perfusion of swine lungs. METHODS: Lungs from unmodified swine and swine expressing human decay-accelerating factor and human CD59 (hDAF/hCD59 swine) were perfused with either human plasma or baboon blood. Pulmonary vascular resistance and static pulmonary compliance were measured serially, and swine lung tissue were examined by light microscopy. Complement activation was assessed by serial measurements of baboon plasma C3a-desArg concentrations. RESULTS: Perfusion of unmodified swine lungs with human plasma and baboon blood resulted in hyperacute lung injury within minutes of perfusion. However, function was preserved in swine lungs expressing human decay-accelerating factor and human CD59. In both study groups, xenogeneic perfusion with baboon blood resulted in at least a sevenfold increase in plasma C3a-desArg levels suggesting transient activation of complement. CONCLUSIONS: Lungs from swine expressing human decay-accelerating factor and human CD59 were resistant to injury during perfusion with human plasma and baboon blood, indicating that complement mediated some of the features of xenogeneic acute lung injury.
Animals↗
Hearts from transgenic pigs constructed with CD59/DAF genomic clones demonstrate improved survival in primates.
We have previously created transgenic pigs bearing the human complement regulatory proteins CD59 and decay-accelerating factor (DAF) by either the intercellular transfer or the cDNA transgenic method. To achieve more physiologic protein expression, we constructed a new line of transgenic pigs with CD59 and DAF human genomic clones. We transplanted these CD59/DAF transgenic pig hearts into baboons immunosuppressed with cyclosporine, methylprednisone or leflunomide/mofetil mycophenolate. The four wild-type hearts survived for 20-80 min, whereas the four CD59/DAF hearts functioned for 85-130 h. Immunohistochemical staining showed levels of CD59 and DAF protein expression similar to that in human hearts. Wild-type and transgenic hearts demonstrate a similar level of IgM deposition, although transgenic hearts suffered less hyperacute rejection and thus less membrane attack complex deposition. The histology of the transgenic grafts after explant was consistent with acute vascular rejection, with a high level of IgG deposit compared with wild-type control. We conclude that this new line of CD59/DAF transgenic pigs express high levels of the transgene products, which conferred longer survival because of better protection from hyperacute rejection. Similar to previous transgenic pigs, however, these animals suffered from delayed xenograft rejection.
Animals↗
Potential use of genetically modified pigs as organ donors for transplantation into humans.
1. Transplantation is currently viewed as a successful treatment for end-stage organ failure. Its more widespread use is severely limited by a shortage of human organ donors. This has stimulated the scientific and medical communities to look at the potential use of animals to solve this problem. For a number of reasons, the pig appears to be the preferred species. 2. The initial immunological problem encountered in pig-to-primate transplantation is a process of hyperacute rejection, which is mediated by the binding of antibodies to the graft endothelium followed by the activation of the complement cascade. We have sought to overcome these initial immunological challenges by focusing our attention not only on the recipient of the graft but also on the donor. Therefore, we have generated transgenic animals with specific genetic modifications designed to inhibit the activation of the complement cascade. Upon transplantation to baboons of organs derived from these transgenic pigs, we have been able to demonstrate that hyperacute rejection can be prevented. We will discuss the generation of these and other transgenic animals and their potential role in clinical xenotransplantation.
Animals↗
Role of CD46 in measles virus infection in CD46 transgenic mice.
The susceptibility of CD46 (human membrane cofactor protein) transgenic mice to measles virus (MV) infection was investigated. Cell cultures (lung and kidney) established from transgenic and control mice showed that although both could be infected only those from the CD46+ mice gave fusion. A complete round of replication with the release of infectious virus was detected exclusively in the transgenic cell cultures whose permissiveness to MV was markedly less than that of Vero cells. The ability of MV to replicate in vivo in mice was studied using both vaccine and laboratory-adapted wild-type strains of virus. After intraperitoneal and intranasal inoculations of transgenic mice, virus replication could not be detected. In contrast intracerebral inoculation induced infection in both transgenic and nontransgenic mice. Our results from in vitro infection studies support the hypothesis that CD46 is a major host cell factor involved in the MV-induced fusion process and MV entry. The studies further indicate that MV tropism is not governed solely by the expression of the CD46 gene and that the high efficiency of the replicative cycles characteristic of fully permissive host cells requires additional factors, which are lacking in both transgenic and nontransgenic mice.
Administration, Intranasal↗
Complement-mediated pulmonary xenograft injury: studies in swine-to-primate orthotopic single lung transplant models.
BACKGROUND: The pathogenesis of acute pulmonary xenograft injury has not yet been determined. The present study evaluates the role of complement in mediating pulmonary xenograft dysfunction by using cobra venom factor (CVF) to deplete recipient complement and transgenic swine, which express human regulators of complement activation (human decay-accelerating factor [hDAF] and hCD59). METHODS: Fifteen orthotopic lung transplants were performed as follows: group I, swine-to-swine (n=5); group II, unmodified swine-to-baboon (n=3); group III, unmodified swine-to-(CVF treated) baboon (n=3); and group IV, hCD59/hDAF swine-to-baboon (n=4). Left pulmonary artery flow and pulmonary vascular resistance were measured at 30-min intervals. Serial lung biopsies were examined by light microscopy and immunofluorescence. The activation of complement was quantified by measurement of baboon plasma CH50 and C4 functional activity. RESULTS: Group II xenotransplants ceased functioning within 30 min of reperfusion. Histopathologic ab normalities included erythrocyte/platelet aggregates and hemorrhagic pulmonary edema. Groups I and IV showed excellent function throughout. hDAF/hCD59 lungs (group IV) showed trace venular fibrin plugs and moderate loss of alveolar architecture. Pretreatment with CVF (group III) was ineffective in preventing xenograft injury. CONCLUSIONS: These results characterize the fundamental features of discordant pulmonary xenotransplantation. Correction of the known defects in the regulation of heterologous complement activation was partially effective in preventing pulmonary xenograft dysfunction, suggesting that complement mediates, in part, some of the features of acute lung injury after discordant lung xenotransplantation.
Animals↗
The role of antibodies in acute vascular rejection of pig-to-baboon cardiac transplants.
Long-term success in xenotransplantation is currently hampered by acute vascular rejection. The inciting cause of acute vascular rejection is not yet known; however, a variety of observations suggest that the humoral immune response of the recipient against the donor may be involved in the pathogenesis of this process. Using a pig-to-baboon heterotopic cardiac transplant model, we examined the role of antibodies in the development of acute vascular rejection. After transplantation into baboons, hearts from transgenic pigs expressing human decay-accelerating factor and CD59 underwent acute vascular rejection leading to graft failure within 5 d; the histology was characterized by endothelial injury and fibrin thrombi. Hearts from the transgenic pigs transplanted into baboons whose circulating antibodies were depleted using antiimmunoglobulin columns (Therasorb, Unterschleisshein, Germany) did not undergo acute vascular rejection in five of six cases. Biopsies from the xenotransplants in Ig-depleted baboons revealed little or no IgM or IgG, and no histologic evidence of acute vascular rejection in the five cases. Complement activity in the baboons was within the normal range during the period of xenograft survival. In one case, acute vascular rejection of a xenotransplant occurred in a baboon in which the level of antidonor antibody rose after Ig depletion was discontinued. This study provides evidence that antibodies play a significant role in the pathogenesis of acute vascular rejection, and suggests that acute vascular rejection might be prevented or treated by therapies aimed at the humoral immune response to porcine antigens.
Acute Disease↗
Transgenic pigs expressing human CD59 and decay-accelerating factor produce an intrinsic barrier to complement-mediated damage.
We characterize a line of transgenic pigs that express the human complement-regulatory proteins human CD59 and human decay-accelerating factor. These genes, under the control of heterologous promoters, are expressed in a variety of organs, including the vasculature of the heart, kidney, and liver. We demonstrate that moderate levels of these gene products are sufficient to protect peripheral blood cells from human or baboon complement. Using pig to baboon heterotopic heart transplants, we show that expression of these proteins is sufficient to block the complement-mediated damage that is the hallmark of such xenografts, when nontransgenic organs are used. These results indicate that there is significant species specificity of intrinsic complement regulatory protein function. This specificity is evident in transgenic organs in which low levels of human CD59 and human decay-accelerating factor expression significantly effect the humoral immune response that causes xenograft rejection. This result suggests that transgenic organs with high levels of human complement-regulatory protein expression will be sufficient to alleviate the humoral immunological barriers that currently block the use of xenogeneic organs for human transplantation.
Animals↗