The endothelial heparan sulfate-antithrombin III natural anticoagulant pathway in normal and transplanted human kidneys

Knockdown of serpin peptidase inhibitor clade C member 1 inhibits the growth of nasopharyngeal carcinoma cells

Nasopharyngeal carcinoma (NPC) is a type of cancer originating in the nasopharynx. There are no NPC‑specific treatments available at present. Serpin peptidase inhibitor clade C member 1 (SERPINC1) serves roles in anticoagulation and anti‑inflammation. The aim of the present study was to investigate the role of SERPINC1 in the proliferation and apoptosis of NPC cells. Tumor and adjacent healthy tissue samples were collected from patients with NPC. Additionally, the SERPINC1 gene was silenced in the HNE3 cell line using short interfering RNA targeted against SERPINC1 (SERPINC1‑siRNA). Cell viability was determined via a Cell Counting Kit‑8 assay; furthermore, proliferation and apoptosis were investigated via flow cytometry. Western blotting and reverse transcription‑quantitative polymerase chain reaction analysis were performed to determine the expression levels of protein and mRNA. It was revealed that the expression levels of SERPINC1 mRNA and protein were increased in NPC tumor tissues compared with in adjacent healthy tissues. The expression of SERPINC1 mRNA and protein in HNE3 cells decreased following SERPINC1‑siRNA transfection. Furthermore, knockdown of SERPINC1 promoted apoptosis and inhibited proliferation. It was also demonstrated that silencing SERPINC1 upregulated the expression of B‑cell lymphoma-2 (Bcl‑2)‑associated X protein and p53 mRNA and protein, and downregulated that of Bcl‑2, survivin and cyclin D1. Downregulation of SERPINC1 reduced the phosphorylation of phosphatidylinositol 3‑kinase (PI3K), protein kinase B (Akt) and mammalian target of rapamycin (mTOR). Thus, SERPINC1 knockdown may promote the apoptosis of HNE3 cells and inhibit proliferation via the suppression of the PI3K/Akt/mTOR signaling pathway.

Prolonged thrombocytopenia after living donor liver transplantation is a strong prognostic predictor irrespective of splenectomy: the significance of ADAMTS13 and graft function [corrected]

The precise mechanism of prolonged thrombocytopenia following living donor liver transplantation (LDLT) remains unclear. To determine risk factors associated with prolonged thrombocytopenia following LDLT, with a focus on the activity of ADAMTS13 (a disintegrin-like and metalloproteinase with thrombospondin type-1 motifs member 13) and the influence of splenectomy. Adult LDLT patients were divided into two groups on the basis of platelet counts (100 × 10(3)/μL) on POD 14: high and low platelet (HP and LP) groups. Survival analysis was performed in the 100 patients, and ADAMTS13 activity and von Willebrand factor (VWF) levels in the plasma were measured in 65 adult recipients. The 6-month survival rate was significantly lower in the LP group (n = 36) than in the HP group (n = 62) (61.1 vs. 93.5 %). ADAMTS13 activity had been significantly lower in the LP group (n = 23) than in the HP group (n = 42). The VWF/ADAMTS13 ratio was significantly higher in the LP group than in the HP group. The independent risk factors for thrombocytopenia on POD14 were preoperative AT levels and ADAMTS13 activity on POD14. TPO levels on POD14 were significantly higher in the LP group than in the HP group, while those on POD28 in the LP group were significantly decreased, despite the low platelet levels. Irrespective of splenectomy, platelet counts and ADAMTS13 activity in the LP group remained low until POD28, while VWF/ADAMTS13 ratio significantly increased until POD28. These results suggest that prolonged thrombocytopenia after LDLT was associated with not only a decrease in ADAMTS13 due to sinusoidal endothelial cell injury, but also low TPO production due to hepatocyte dysfunction, irrespective of splenectomy [corrected].

Antithrombin III inhibits lymphocyte proliferation, immunoglobulin production and mRNA expression of lymphocyte growth factors (IL-2, gamma-IFN and IL-4) in vitro

BACKGROUND

Antithrombin III (AT-III) is a physiological inhibitor of thrombin and other serine proteases, and has antiinflammatory properties. Thrombin is known to enhance T lymphocyte activation in vitro and serine proteases can act as costimulators for lymphocyte proliferation and cytokine production. We have previously shown that AT-III significantly inhibited allograft rejection in a highly histoincompatible model of rat lung transplantation and in vitro cell proliferation in ConA-stimulated rat spleen cells. In this study, we examined the involvement of cytokine gene expression in the above inhibitory effect of AT-III. We also examined the effect of AT-III on several in vitro immune reactions in human peripheral blood mononuclear cells (PBMCs).

METHODS

mRNA expression of cytokines/cytokine receptor important in lymphocyte activation was examined. Rat spleen cells were stimulated with Con-A with/without AT-III and submitted for reverse transcriptase-polymerase chain reaction (RT-PCR). To assess the effect of AT-III on human PBMCs, we examined the effects of AT-III on cell proliferation of human PBMCs stimulated in mixed lymphocyte reaction (MLR) (allogeneic stimulation), with OKT3 (T cell receptor activation) and with PHA (mitogenic stimulation). The effect of AT-III on PWM-stimulated immunoglobulin (Ig) production by human PBMCs was also examined. All experiments for cell proliferation were performed in 10% serum and in serum-free (SF) media to determine whether AT-III exerted its effects through its interaction with thrombin in serum.

RESULTS

mRNA expression of IL-2, gamma-IFN and IL-4 in ConA-stimulated rat spleen cells was nearly completely inhibited by AT-III at 15 IU/ml. mRNA levels for IL-6, IL-2R and TGF-beta1 were not significantly affected by AT-III. AT-III showed a dose-dependent inhibition of cell proliferation in human PBMCs. At 15 IU/ml, cell proliferation was inhibited by approximately 86%, approximately 81% and approximately 56% in the MLR-, OKT3- and PHA-stimulated PBMCs, respectively in both serum and SF media. AT-III inhibited PWM-stimulated Ig production in a dose-dependent manner. IgG, IgM and IgA production was reduced by approximately 60%, 80% and 70%, respectively in cultures incubated with 15 IU/ml AT-III.

CONCLUSIONS

(1) Inhibition of IL-2, gamma-IFN and IL-4 mRNA expression might be responsible for inhibition of cell proliferation by AT-III in ConA-stimulated rat spleen cells, (2) AT-III inhibits cell proliferation in the MLR-, OKT3- and PHA-stimulated human PBMCs, and Ig production in PWM-stimulated human PBMCs, (3) The immune regulatory effects of AT-III are independent of its interaction with thrombin since similar levels of suppression were seen in SF media, and (4) These results suggest that AT-III has potent inhibitory effects on lymphocyte activation and cytokine production and may have potential applications as an immunomodulatory agent.

Vascular antithrombin and clinical outcome in heart transplant patients

A procoagulant microvasculature is associated with accelerated development of coronary artery disease (CAD) and failure in heart transplant patients. This study was performed to evaluate how changes in natural anticoagulation within cardiac allografts affect outcome. We prospectively studied 141 consecutive cardiac allograft recipients who underwent transplantation between 1988 and 1997. Serial endomyocardial biopsy specimens (6.5 +/- 0.1 biopsy specimens/patient) obtained during the first 3 months after transplantation were studied immunohistochemically to evaluate vascular antithrombin, and annual coronary angiograms (3.8 +/- 0.2 angiograms/patient) were studied to evaluate CAD. Antithrombin was present in arteries and veins, but not in capillaries, of all donor heart biopsy samples. Allografts that maintained vascular antithrombin had the best prognosis. Allografts with early and persistent loss of vascular antithrombin (n = 21) developed CAD earlier (p < 0.001), developed more severe disease (p < 0.001), showed more disease progression (p < 0.001), and failed more often (p = 0.003) and earlier (p < 0.001) than allografts retaining normal vascular antithrombin (n = 45). However, allografts that lost and recovered vascular antithrombin while developing unusual capillary antithrombin binding (n = 75) had less CAD, developed CAD later, had less severe disease and less disease progression (p < 0.01), and failed less often (p = 0.01) and later (p = 0.03) than allografts with persistent loss of vascular antithrombin. The persistent lack of a thromboresistant microvasculature increases risk of subsequent CAD and graft failure. However, recovery of vascular antithrombin and development of unusual capillary antithrombin binding improves allograft outcome.

Localization and characterization of antithrombin in human kidneys

Antithrombin is a serine protease inhibitor that is critical in maintaining a thromboresistant vasculature. The association between low serum antithrombin concentration and renal disease suggests that the kidney plays a role in the conservation of plasma antithrombin. We used immunohistochemical techniques to determine the spatial distribution, heparin binding characteristics, and intracellular and intercellular localization of antithrombin in biopsy specimens (n = 53) of human donor kidneys obtained at the time of transplantation. In the renal cortex, double antibody techniques demonstrated the presence of intracellular antithrombin in proximal tubule epithelial cells. The reactivity was granular and was co-localized with vesicle-like structures. Distal and collecting tubules did not demonstrate intraepithelial antithrombin reactivity. No tubule structures in the medullary region demonstrated intracellular antithrombin, but all these structures showed intense basement membrane antithrombin reactivity. Double antibody techniques also demonstrated that the heparin binding domain of intraepithelial antithrombin was occupied. Semiquantitative scores for intraepithelial antithrombin were significantly decreased in renal biopsy specimens obtained 30 min after anastomosis compared with biopsies from the same organ obtained before anastomosis. These findings suggest that antithrombin, probably in association with heparin or heparan sulfate, is internalized by renal proximal epithelial cells. Although the ultimate fate of intraepithelial antithrombin is not known, this may represent a mechanism by which the kidney helps to maintain plasma antithrombin concentrations.

Antithrombin III treatment improves parameters of acute inflammation in a highly histoincompatible model of rat lung allograft rejection

BACKGROUND

Antithrombin III (AT-III) is an antithrombotic agent with known anti-inflammatory properties that is also known to attenuate acute inflammation, prevent ischemia-reperfusion injury, and disseminated intravascular coagulation (DIC) associated with sepsis and endotoxemia. Here, we examined the ability of AT-III to modify parameters of acute inflammation in a highly histoincompatible model of rat lung allograft rejection (AR).

METHODS

After left single lung transplantations (BN-->Lew), recipient animals were treated i.v. with 50 U/kg of human AT-III (low dose group), 500 U/kg of human AT-III (high dose group), or normal saline (control group) on days 2 and 4 posttransplant. All animals were sacrificed on day 6, and several pathological categories of acute inflammation related to AR were scored (0-4). The effect of AT-III on concanavalin A (Con A)-stimulated rat spleen cell proliferation was also examined.

RESULTS

The stage of AR, and the degrees of edema, hemorrhage, and necrosis were significantly reduced in the high dose group compared with the control group. AT-III significantly inhibited rat spleen cell proliferation in response to Con A, in a dose-dependent manner. Maximal inhibition was seen at 15 U/ml in culture. Identical inhibition of Con-A-stimulated cultures occurred in both serum free and serum-containing media, indicating that AT-III inhibition of Con-A-stimulated rat spleen cell proliferation is independent of its actions on thrombin.

CONCLUSIONS

1) AT-III treatment significantly improves parameters of acute inflammation seen in a highly histoincompatible model of rat lung AR. 2) AT-III inhibits in vitro T cell proliferation to the potent mitogen Con A, suggesting that protease inhibition may inhibit T cell activation in vitro. 3). The beneficial effects of AT-III on parameters of lung AR relate to the anti-coagulant, anti-inflammatory, and possibly immunoregulatory actions of AT-III.

A stable prostacyclin analog, beraprost sodium, attenuates platelet accumulation and preservation-reperfusion injury of isografts in a rat model of lung transplantation

BACKGROUND

Recent studies have shown that the extent of platelet accumulation in the vasculature of transplanted organs correlates with the degree of preservation-reperfusion injury. In this study, we examined the effect of a stable prostacyclin analog, beraprost sodium, which possesses potent antiplatelet activity, on parameters of platelet accumulation and preservation-reperfusion injury of isografts in a rat model of lung transplantation.

METHODS

The heart-lung blocks of donor rats were flushed with and preserved in modified Euro-Collins solution at 4 degrees C for 6 hr or 24 hr. The left lung was transplanted into recipient rats and reperfused for 1 hr. Lung injury was evaluated by the pulmonary blood flow ratios to the lung isografts, the weight gain of the isografts, and histological examination. Small portions of the lung isografts were excised and stained with an antibody specific for rat platelets. A scoring system was developed to semiquantitate the intensity of antibody staining (score 0-4). The recipient rats received oral administration of beraprost sodium (0.3 mg/kg) before lung transplantation. Control animals received no beraprost sodium.

RESULTS

In the 6-hr preservation study, administration of beraprost sodium significantly reduced the score for platelet accumulation (1.8+/-0.4 vs. 3.3+/-0.5, P<0.01). This observation was accompanied by a significantly decreased degree of preservation-reperfusion injury as evidenced by an increased blood flow ratio (13.7+/-2.6% vs. 4.5+/-3.6%, P<0.01) and a reduced weight gain (0.7+/-0.2 g vs. 1.1+/-0.2 g, P<0.01). Histological examination revealed severe capillary congestion in three of six cases in the control group, while no capillary congestion was observed in the beraprost group. In the 24-hr preservation study, no differences were seen in platelet accumulation scores or parameters of lung injury.

CONCLUSION

Beraprost sodium, an antiplatelet agent, reduces platelet accumulation and preservation-reperfusion injury of lung transplants at 6 hr in this rat isograft model.

Tubular antithrombin at transplantation determines subsequent renal allograft function

BACKGROUND

Antithrombin is found in the microvasculature and tubules of normal and transplanted human kidneys. Although depletion of vascular antithrombin is associated with renal allograft dysfunction, neither the distribution nor clinical significance of tubular antithrombin is known.

METHODS

Changes in tubular antithrombin in biopsy specimens (n=41) obtained from donor kidneys at transplantation were studied immunohistochemically. The relationship between these changes and subsequent graft function was analyzed.

RESULTS

Granular intracellular antithrombin was found only within the proximal tubular epithelium. Allografts with depleted tubular antithrombin at transplantation (n=20) had significantly greater plasma creatinine concentrations at posttransplant days 3 (P < 0.001) and 5 (P < 0.03) than allografts with normal tubular antithrombin (n=21). Indeed, depletion of tubular antithrombin at transplantation correlated with the degree of graft dysfunction at 3 days after transplantation.

CONCLUSIONS

Depleted tubular antithrombin at transplantation is associated with reduced early graft function, and this may identify patients at risk of a complicated follow-up.

Expression of tissue type plasminogen activator and type 1 plasminogen activator inhibitor, and persistent fibrin deposition in chronic renal allograft failure

Persistent fibrin deposition has been observed in kidneys undergoing chronic rejection, and has been suggested to contribute to the obliteration of the vasculature in these grafts. The mechanisms leading to it are not clear. Fibrinolysis, the process to remove fibrin in tissues, is initiated by tissue type plasminogen activator (tPA) and suppressed by type 1 plasminogen activator inhibitor (PAI-1). To investigate their roles in chronic rejection and fibrin deposition, we serially examined the expression of tPA and PAI-1 in an unmodified chronic rejection model, using a Fisher 344 to Lewis rat renal transplant, at 0, 2, 4, 6, 10, 12, 16 and 20 weeks post-transplantation (N = 4 rats/time point in each group). We also analyzed fibrin deposition and the development of chronic changes in the grafts. Our results show that tPA was up-regulated only in the acute phase of rejection (P < 0.05), whereas PAI-1 was induced and persistently expressed during the progressive phase of chronic rejection, together with persistent fibrin deposition in the grafts. Immunohistochemistry showed PAI-1 was mainly localized to the damaged/proliferative vascular intima. The results suggest that persistent induction of PAI-1 may be responsible for the continuance of fibrin deposition, which is associated with irreversible damage and chronic graft loss.

Heparan-dependent endothelial antithrombin binding is increased by butyrate

Heparin biosynthesis involves a critical early step of N-deacetylation which is inhibited by the short chain fatty acid n-butyrate. Such inhibition causes mast cells to produce heparins with high affinity for antithrombin (AT). We have cultured endothelial cells in media supplemented with short chain fatty acids and have found that isobutyric, propionic and valeric acids cause significant increases in endothelial binding of AT measured by flow cytometry, but n-butyric acid was the most effective fatty acid to increase AT binding. Such binding,was heparan sulfate-dependent, for it was decreased significantly by pre-treatment of the cells with heparinase. These findings suggest that inhibition of N-deacetylation in heparan biosynthesis affects sulfation and results in the distribution of negative charges and conformation changes within the heparan domain that binds AT to endothelial plasma membranes. These changes also were associated with up-regulation of the intercellular adhesion molecule-1, which is a marker of endothelial activation.

The effect of sex and age on antithrombin biosynthesis in the rat

Antithrombin is the primary inhibitor of Factor Xa and thrombin. Numerous reports have indicated that age and sex can influence antithrombin levels, but details of the regulation of antithrombin biosynthesis are not known. Thus, a characterization of antithrombin mRNA in eight tissues of young and old male and female rats was carried out. Liver produced the most mRNA, and hence contributes the majority of the plasma antithrombin, followed by the kidneys, with no age or sex related differences in mRNA levels being observed. Elevated amounts of mRNA were detected in aortas of old male rats compared to young ones. No antithrombin mRNA was detected in brain, lung, heart or skeletal muscle, and spleen showed low but variable levels. Plasma antithrombin protein was elevated in old female rats compared to young female or old male rats. These results show that the rat provides a potentially useful system to study the in vivo regulation of antithrombin biosynthesis.

Tissue plasminogen activator, plasminogen activator inhibitor-1, and fibrin as indexes of clinical course in cardiac allograft recipients. An immunocytochemical study

BACKGROUND

Tissue-type plasminogen activator (TPA) is the principal activator of plasminogen. Since hemostasis in the microcirculation of allografts is a well-recognized complication of transplantation, we asked (1) whether the distribution and amount of cellular TPA in biopsies of transplanted human hearts are associated with fibrin deposits in and around the microcirculation, (2) whether such changes involve the physiological inhibitors of TPA and plasmin, and (3) whether the presence of these activators and inhibitors of fibrinolysis in tissue is correlated with clinical outcome.

METHODS AND RESULTS

We immunocytochemically quantified the presence of fibrin, plasmin, TPA, and the TPA inhibitor PAI-1 in 938 biopsies from 68 consecutive cardiac allografts over a 54-month period. The localization, distribution, and quantification of TPA in arteriolar smooth muscle cells revealed that 35 of the 68 allografts maintained vascular TPA reactivity consistent with time-zero biopsies of autologous donor hearts: this was designated as the normal TPA group. In contrast, 33 of the 68 allografts significantly lost vascular TPA reactivity compared with time-zero biopsies of autologous donor hearts: this was designated as the depleted TPA group. Analysis of sequential biopsies from both groups during 54 months revealed that the mean cumulative quantitative TPA value for the normal TPA group was 1.0 +/- 0.01, whereas the depleted TPA group value was 1.9 +/- 0.02 (P = .0001), and the mean cumulative quantitative fibrin value for the normal TPA group was 1.0 +/- 0.01, whereas the depleted TPA group value was 1.5 +/- 0.05 (P = .0001). Biopsies of allografts in the depleted TPA group contained endothelial reactivity for TPA-PAI-1 complexes, whereas biopsies from the normal TPA group did not. Plasmin-associated molecules were rarely identified in biopsies of the normal TPA group but were present in the depleted TPA group, and the fibrin-to-plasmin ratio in the normal TPA group always was less than the fibrin-to-plasmin ratio in biopsies from the depleted TPA group. Analysis of demographic and risk factors revealed no significant differences between patients in the normal and depleted TPA groups, but none of the 35 patients in the normal TPA group died or were retransplanted, and 13 of the 33 patients in the depleted TPA group died or required retransplantation (P = .0001).

CONCLUSIONS

Time-zero hearts (n = 68) and 34 of 38 stable allografts contained immunocytochemically detectable TPA only in vascular smooth muscle cells. Twenty-nine of 30 patients with normal TPA in their time-zero biopsies who subsequently developed a poor clinical outcome were found to have depleted TPA in biopsies evaluated during their first postoperative month and remained depleted throughout the study. Of 33 patients with depleted TPA, 39% died or required retransplantation. Depleted arteriolar TPA associated significantly with vascular and interstitial deposits of fibrin, plasmin, and endothelial TPA-PAI-1 complexes. These findings indicate that hemostatic and fibrinolytic pathways are activated in falling allografts, and they reveal evidence of depleted TPA before clinical or histopathological signs of failure. Patients with such allografts were found to be at high risk of death independently of other widely used clinical/laboratory parameters of prediction.

Role of heparan sulfate in immune system-blood vessel interactions

Heparan sulfate proteoglycan, a component of endothelial cell membranes and extracellular matrices, is involved in a number of the critical functions of endothelium and of antigen-presenting cells. This review discusses how heparan sulfate is released from endothelial cells during inflammation, how the loss of heparan sulfate potentially alters endothelial cell physiology, and how the presence of heparan sulfate in a soluble form might regulate the functioning of lymphocytes at sites of inflammation.

Vascular events in placentae and organ allografts

This investigation explores the transplantation analogy of placentae with allografted human organs. Biopsies of cardiac and renal allografts and placentae were studied immunocytochemically with antibodies to components of the immunological, coagulational, anticoagulational, and fibrinolytic systems. Cellular rejection of cardiac and renal allografts was identified by infiltrating lymphocytes and macrophages. This was accompanied by vascular damage characterized by loss of endothelial anticoagulant pathways, vascular deposits of fibrin, and depletion of arterial tissue plasminogen activator (tPA). Failing allografts, including placentae from abnormal pregnancies, demonstrated coagulation/fibrinolytic changes consistent with vascular rejection, regardless of the presence of cellular infiltrates. An IgM autoantibody to allogeneic endothelium was associated with vascular protection. Its presence in cardiac and renal transplant biopsies was associated with an absence of fibrin deposits, and its absence was associated with vascular damage. Atherosclerosis commonly was identified in allograft biopsies (including placentae from abnormal pregnancies). These changes were shown in serial biopsies of transplanted hearts to be preceded by or associated with diminished IgM autoantibody, impaired endothelial anticoagulant pathways, vascular fibrin deposits, and depleted arterial reactivity for tPA. These results indicate the transplantation analogy of pregnancy should be viewed more specifically as vascular smooth muscle cell and endothelial responses to as yet unidentified microenvironmental stimuli.

Microvascular perturbations in human allografts: analogies in preeclamptic placentae

The thromboresistance of endothelium is maintained as long as natural anticoagulant pathways are functionally present on endothelial plasma membranes. The principal anticoagulant pathways in human hearts and kidneys are thrombomodulin (TM) and heparan sulfate proteoglycan-antithrombin III (HSPG-ATIII). The downregulation of TM or the loss of ATIII is associated with fibrin deposition. This sequence of events occurs when stable allografts of hearts or kidneys become unstable or rejected. Human placentae do not contain the HSPG-ATIII natural anticoagulant pathway, but the TM system is uniformly represented on endothelium of normal chorionic villi. However, many villi in placentae from preeclamptic pregnancies contain thrombomodulin-negative endothelium, and these vessels contain fibrin thrombi. These thrombi compromise blood flow through the placental microcirculation and are associated with ischemic changes either with or without the presence of cellular infiltrates.

Fetal stem vessel endothelial changes in placentae from normal and abnormal pregnancies

Areas of immunocytochemically defined immunopathology are common in placentae from secondary recurrent spontaneous aborters. Endothelial cells of affected villi were found to be negative for the thrombomodulin natural anticoagulant pathway, and these cells were reactive with monoclonal antibodies to tissue factor and fibrin. Endothelial cells of normal villi adjacent to affected villi also were negative for thrombomodulin and positive for tissue factor and fibrin, but endothelium of normal villi distant to affected villi were thrombomodulin-positive, tissue factor-negative, and did not contain deposits of fibrin. These findings indicate that a loss of endothelial anticoagulant activity precedes the onset of immunopathology. This observation, coupled with the findings that fetal stem vessels normally lack the heparan sulfate proteoglycan-antithrombin III natural anticoagulant pathway and that normal cord blood contains a heparin-like anticoagulant, suggest that a failure of endothelial anticoagulation may be a primary event in the development of placental immunopathology.