The relationship of ischemia-reperfusion injury of transplanted lung and the up-regulation of major histocompatibility complex II on host peripheral lymphocytes.

OBJECTIVES: This study was designed to examine the relationship between ex vivo preservation time of the transplanted lung and the extent of injury and to relate this to the severity of rejection with and without allogenicity. METHODS: Single lung transplantation was performed on two groups of domestic swine. Group A (n = 7) and group B (n = 6) had ex vivo preservation times of 4 and 15 hours, respectively, at 4 degrees C hypothermia. Group C (n = 6) underwent 2 hours of warm ischemia via dissection and isolation of the left lung with ligation of its bronchial artery and crossclamping of the left pulmonary artery, vein, and bronchus without explantation. Assessment measures included lung function, antioxidant enzyme activities in the plasma and lung tissue, levels of inflammatory mediators in the recipient plasma, and quantification of major histocompatibility complex II HLA-DR-beta on host peripheral lymphocytes. RESULTS: All groups demonstrated increases in interleukin-10, lung weight, and HLA-DR-1beta expression and decreases in lung-tissue antioxidant enzyme activities, gas exchange, and lung compliance. There was a strong positive correlation between ex vivo preservation time and the expression of HLA-DR-beta and a negative correlation between ischemic time and lung-tissue superoxide dismutase. CONCLUSIONS: These results suggest that the intensity of the host immunogenic response is related to the severity of ischemia-reperfusion injury and is independent of tissue incompatibility and/or the type of ischemic insult. We conclude that the extension of ex vivo preservation time may predispose the transplanted lung to more severe rejection.

Prominence of apolipoproteins B, (a), and E in the intimae of coronary arteries in transplanted human hearts: geographic relationship to vessel wall proteoglycans.

BACKGROUND: Transplant arteriopathy (TA) is characterized by vessel wall thickening with prominent glycosaminoglycan and lipid deposits. In this light, we have recently demonstrated the distribution of proteoglycans in allograft coronary arteries. The aim of this study is to examine the distribution of apolipoproteins within allograft coronary arteries and to investigate their localization in relation to proteoglycans. METHOD: Particular transverse sections of left and right epicardial coronary arteries from 46 human cardiac allografts, 11 normal hearts, and 11 hearts with native atherosclerosis were stained immunohistochemically for apolipoprotein B, apolipoprotein (a) (apo[a]), apolipoprotein E (apoE), biglycan, decorin, and versican by use of an automated immunostainer. RESULTS: Apo(a) and apoE immunopositivity in TA was much more intense than that in native atherosclerosis, whereas the reverse was true for apoB. Prominent apoE deposits were evident circumferentially in endothelia and extracellularly in superficial intima of mildly diseased TA, as well as in deeper intima of severely diseased TA. Apo(a) had a staining pattern very similar to apoE except for a patchy deposition also seen in TA media. The intimal areas staining prominently with apoE or apo(a) in TA arteries corresponded very closely to the areas with proteoglycan deposits, especially versican. CONCLUSION: The distinctive patterns of apolipoprotein accumulation in TA and native atherosclefosis appear to reflect different pathogenetic processes in the two conditions. The colocalization of proteoglycans and apolipoproteins in TA intima supports the hypothesis that interactions between proteoglycans and apolipoproteins influence lipid retention and overload in allograft coronary arteries.

Biglycan, decorin, and versican protein expression patterns in coronary arteriopathy of human cardiac allograft: distinctness as compared to native atherosclerosis.

BACKGROUND: Histochemical staining has demonstrated previously dramatic deposits of glycosaminoglycans associated with prominent lipid accumulations in thickened vessel walls of allograft coronary arteries. In this study, we characterized the amount, distribution, and types of proteoglycan in the walls of coronary arteries from human cardiac allografts and from native atherosclerotic (NA) controls as part of a strategy to understand the pathogenesis of transplant arteriopathy (TA). METHOD: We used polyclonal rabbit antibodies against human biglycan, decorin, and versican localize the proteoglycan molecules in standardized transverse sections of the proximal left anterior descending and right coronary arteries. Slides were scored in a blinded fashion for intensity of proteoglycan staining (0 to 6+) and for localization in the vessel walls. RESULTS: Unique patterns of proteoglycan distribution were present in TA and NA. Biglycan was particularly prominent in intima and evolving atheromata in severely diseased TA coronary arteries, but not in NA. Decorin was present mainly in adventitia of all vessels and in the intima of NA. Prominent versican accumulation occurred in intima and media of TA coronaries, associated with smooth muscle cells and foam cells. There was a reciprocal pattern of biglycan and decorin staining. Versican colocalized with biglycan. Intimal biglycan and versican deposits were positively correlated to the extent of luminal narrowing in TA. CONCLUSION: The distinctive staining patterns for biglycan, decorin and versican in both native and allograft disease indicate that the synthesis and distribution of these proteoglycans are regulated by different local mechanisms in different atheromatous diseases.

Prominence of coronary arterial wall lipids in human heart allografts. Implications for pathogenesis of allograft arteriopathy.

Transplant arteriopathy is a major late complication in human heart allograft recipients and the pathogenesis of such arteriopathy remains uncertain. The degree to which lipids and atheromata are involved in the arteriopathic lesions remains unsettled, and there is uncertainty regarding the significance of insudation or retention of lipids within the coronary artery walls of transplanted hearts. On current immunosuppressive regimens, most patients experience an increased serum total cholesterol and low-density lipoprotein cholesterol after transplant. Elevation of these blood lipids has an undetermined relationship to arteriopathy. We carried out morphological, morphometric, immunohistochemical, ultrastructural, and biochemical studies of particular coronary artery segments from 23 unselected explant or autopsy allografts and donor age-matched native coronary controls. Patients died of cardiac and non-cardiac reasons over a period of 4 to 1610 days after transplant. Atheromata were frequent, and diffuse intra- and extra-cellular accumulation of lipids in both intimal and medial walls was documented by oil red O positivity, immunohistochemical staining (muscle-specific alpha-actin), transmission and scanning electron microscopy, and biochemical analysis. Mean total cholesterol, esterified cholesterol, free cholesterol, and phospholipid content (microgram/cm2 intimal surface area) and concentration (microgram/mg dry defatted weight) in arteriopathic coronaries were > 10-fold higher than in comparable native coronary segments. Extent of lipids in the arterial walls was highly correlated with digitized percent luminal narrowing, mean daily and cumulative cyclosporin dose, and mean cumulative prednisone dose. Our data suggests strongly that lipid accumulation is an important early and persistent phenomenon in the development of transplant arteriopathy.

Molecular cloning of murine intercellular adhesion molecule (ICAM-1).

We have previously reported a murine lymphocyte surface antigen MALA-2 of approximately 95,000 Mr which is expressed mainly on activated lymphocytes. The rat monoclonal antibody YN1/1 that detects this antigen profoundly inhibits mixed lymphocyte response. We have now purified MALA-2 and determined its partial amino acid sequence. By using non-redundant synthetic oligonucleotides as probes, based on the amino acid sequence, we have isolated two full length cDNA clones encoding MALA-2. The two clones are identical except for the 5' end sequence. Expression of MALA-2 on transfected COS cells is only achieved with one of the two cDNA clones. The nucleotide sequence as well as the deduced amino acid sequence of MALA-2 display striking homology with those of the recently reported human intercellular adhesion molecule ICAM-1. All the unique features of the human ICAM-1, including its homology with the neural adhesion molecule NCAM, its internal repeat structure and the immunoglobulin-like structure, are found in MALA-2. Furthermore, purified MALA-2 crosslinked to a solid support binds Con A blasts that express LFA-1, the putative receptor for ICAM-1, and the binding can be blocked by YN1/1 antibody or antimurine LFA-1 antibody indicating a direct interaction of these molecules in cell adhesion. Therefore, we consider MALA-2 to be the murine homolog of human ICAM-1. Since ICAM-1 is known to be of primary importance in immune responses and inflammatory reactions, having a monoclonal antibody and a mouse model will provide the opportunity to study the functional role of ICAM-1 in vivo.