Treatment of chronic renal allograft rejection in rats with a low-molecular-weight heparin (reviparin)

Prevention of Triglyceridemia by (Non-)Anticoagulant Heparin(oids) Does Not Preclude Transplant Vasculopathy and Glomerulosclerosis

Background: In renal transplantation, chronic transplant dysfunction (CTD) is associated with increased PCSK9 and dyslipidemia. PCSK9 is an enzyme that increases plasma cholesterol levels by downregulating LDLR expression. We recently showed increased PCSK9-syndecan-1 interaction in conditions of proteinuria and renal function loss. Treatment with heparin(oids) might be a therapeutic option to improve dyslipidemia and CTD. We investigated the effects of (non-)anticoagulant heparin(oids) on serum lipids, syndecan-1 and PCSK9 levels, and CTD development. Methods: Kidney allotransplantation was performed from female Dark Agouti to male Wistar Furth recipients. Transplanted rats received daily subcutaneous injections of saline, unfractionated heparin, and RO-heparin or NAc-heparin (2 mg heparin(oid)/kg BW) until sacrifice after 9 weeks of treatment. Results: Saline-treated recipients developed hypertension, proteinuria, and loss of creatinine clearance (all p < 0.05 compared to baseline), along with glomerulosclerosis and arterial neo-intima formation. Saline-treated recipients showed significant increase in plasma triglycerides (p < 0.05), borderline increase in non-HDLc/HDLc (p = 0.051), and ∼10-fold increase in serum syndecan-1 (p < 0.05), without significant increase in serum PCSK9 at 8 weeks compared to baseline. Heparin and non-anticoagulant RO-heparin administration in transplanted rats completely prevented an increase in triglycerides compared to saline-treated recipients at 8 weeks (both p < 0.05). Heparin(oids) treatment did not influence serum total cholesterol (TC), plasma syndecan-1 and PCSK9 levels, creatinine clearance, proteinuria, glomerulosclerosis, and arterial neo-intima formation, 8 weeks after transplantation. Combining all groups, increased syndecan-1 shedding was associated with TC (r = 0.5; p = 0.03) and glomerulosclerosis (r = 0.53; p = 0.021), whereas the non-HDLc/HDLc ratio was associated with the neo-intimal score in the transplanted kidneys (r = 0.65; p < 0.001). Conclusion: Prevention of triglyceridemia by (non-)anticoagulant heparin(oids) neither influenced PCSK9/syndecan-1 nor precluded CTD, which however did associate with the shedding of lipoprotein clearance receptor syndecan-1 and the unfavorable cholesterol profile.

Increased migration of antigen presenting cells to newly-formed lymphatic vessels in transplanted kidneys by glycol-split heparin

Background

Chronic renal transplant dysfunction is characterized by loss of renal function and tissue remodeling, including chronic inflammation and lymph vessel formation. Proteoglycans are known for their chemokine presenting capacity. We hypothesize that interruption of the lymphatic chemokine–proteoglycan interaction interferes with the lymphatic outflow of leukocytes from the renal graft and might decrease the anti-graft allo-immune response.

Methods

In a rat renal chronic transplant dysfunction model (female Dark-Agouti to male Wistar Furth), chemokines were profiled by qRT-PCR in microdissected tubulo-interstitial tissue. Disruption of lymphatic chemokine–proteoglycan interaction was studied by (non-anticoagulant) heparin-derived polysaccharides in vitro and in renal allografts. The renal allograft function was assessed by rise in plasma creatinine and urea.

Results

Within newly-formed lymph vessels of transplanted kidneys, numerous CD45⁺ leukocytes were found, mainly MHCII⁺, ED-1^-, IDO^-, HIS14^-, CD103^- antigen presenting cells, most likely representing a subset of dendritic cells. Treatment of transplanted rats with regular heparin and two different (non-)anticoagulant heparin derivatives revealed worsening of kidney function only in the glycol-split heparin treated group despite a two-fold reduction of tubulo-interstitial leukocytes (p<0.02). Quantitative digital image analysis however revealed increased numbers of intra-lymphatic antigen-presenting cells only in the glycol-split heparin group (p<0.01). The number of intra-lymphatic leukocytes significantly correlates with plasma creatinine and urea, and inversely with creatinine clearance.

Conclusions

Treatment of transplanted rats with glycol-split heparin significantly increases the number of intra-lymphatic antigen presenting cells, by increased renal diffusion of lymphatic chemokines, thereby increasing the activation and recruitment of antigen presenting cells towards the lymph vessel. This effect is unwanted in the transplantation setting, but might be advantageous in e.g., dendritic cell vaccination.

Low-molecular-weight heparins do not modify obliterative airway disease in rat tracheal allografts

Immunosuppressive and antiproliferative effects of heparin may be beneficial in the field of solid organ transplantation. The aim of this study was to examine the effect of low-molecular-weight heparin (LMWH) compounds on the development of obliterative airway disease (OAD) in the rat tracheal transplant model. Allogenic heterotopic tracheal transplantations were performed from Brown-Norway into Lewis rats. Recipients were treated either with nadroparin, enoxaparin, parnaparin, or vehicle from day 0 until harvesting at day 7 or 21. Graft rejection was morphometrically assessed to determine the extent of luminal obliteration end epithelial necrosis. All tracheal grafts harvested at day 7 demonstrated nearly equivalent degree of luminal obstruction regardless of treatment regimen. Likewise, at day 21 the extent of airway narrowing and the degree of inflammatory cell infiltration were similar among the groups. Moreover, loss of airway epithelium was not prevented by LMWH treatments. Finally, intragraft mRNA expression for transforming growth factor-β1 and platelet-derived growth factor-A, interleukin-2, interferon-γ, and monocyte chemoattractant protein-1 did not differ between the groups. In contrast with findings in other animal models, treatment with LMWH preparations did not modify the development of OAD in rat tracheal allografts.

The Importance of Glomerular Deposits of Von Willebrand Factor in Human Renal Allografts

OBJECTIVE

The aim of this study was to evaluate the importance of glomerular expression of von Willebrand factor (vWF) in human renal allografts.

METHODS

We investigated graft biopsies from 72 renal transplant recipients, 40 with acute rejection (AR) and 32 with chronic allograft nephropathy (CAN). All biopsy specimens were immunostained with vWF and CD68 and graded using 3-tiered scales. The follow-up biopsies of patients with AR were reevaluated for development of glomerular sclerosis.

RESULTS

A significant difference was found between type 1 and type 2 AR with regard to glomerular vWF expression (P < 0.01). None of the patients with type 1 AR showed mesangial vWF expression, but 36.4% of patients with type 2 AR showed segmental mesangial vWF expression. In follow-up biopsies, 18 of 40 patients developed significant glomerular sclerosis, and patients with mesangial vWF expression (grade 3 GvWF) showed glomerular sclerosis earlier than did others (P < 0.01). In addition, the outcome for grafts that showed grade 3 glomerular vWF was significantly worse than was the outcome noted for grafts that showed grade 1 or grade 2 glomerular vWF (P < 0.001). Half of the biopsy specimens in the CAN group showed global mesangial vWF expression. Glomerular macrophage infiltration was correlated with degree of glomerular vWF expression both in the AR and in the CAN groups (P < 0.05, P= 0.001, respectively).

CONCLUSION

We hypothesized that the increasing amount of glomerular vWF may be used as a marker of acute vascular rejection and may help for the evaluation of renal allograft biopsies without sufficient arteries. In addition, it can also be a marker for development of early glomerular sclerosis and may help us determine which patients are in need of further treatment.

Influence of hypersulfated and low molecular weight heparins on ischemia/reperfusion: injury and allograft rejection in rat kidneys

The aim of the study was to evaluate the effect of the hypersulfated nonanticoagulant heparin derivative LU 51198 (LU) and of the low molecular weight heparin reviparin (REVI) on ischemia/reperfusion (I/R) injury, acute rejection (AR) and chronic allograft nephropathy (CAN) in rats. Organs were harvested 5 days after 60 min of renal I/R injury. For investigation of AR and CAN we used the allogeneic Fisher-Lewis model. Kidneys were harvested at one respectively 32 weeks after transplantation. Rats were treated with either vehicle, LU or REVI. After I/R injury, treatment with REVI or LU reduced infiltration with MHC II and R73-positive cells, whereas only REVI reduced ED1-positive cells and expression of monocyte chemoattractant protein-1. There was no effect of REVI and LU on acute allograft rejection. Treatment with LU or REVI reduced glomerular infiltration with ED1 and MHCII-positive cells and renal expression of transforming growth factor-beta 32 weeks after transplantation. Only REVI treatment reduced albuminuria, interstitial infiltration and histological signs of CAN. LU, and in a more potent manner REVI, reduce signs of CAN and renal inflammation after I/R injury. Chemically modified heparins without anticoagulatory effects may offer a new treatment option in preventing I/R injury and CAN in human kidney transplantation.

Effects of low molecular weight heparin in obstructed kidneys: decrease of collagen, fibronectin and TGF-β, and increase of chondroitin/dermatan sulfate proteoglycans and macrophage infiltration

BACKGROUND

Heparin exerts beneficial effects in different experimental models of nephropathy, as observed by the preservation of the structural morphology of the kidney after heparin therapy. Here we investigate molecular and cellular events involved in the protective effects of heparin in the progression of renal disease after unilateral ureteral obstruction.

METHODS

Thirty-six rats were divided into six groups: group C (control) was not subjected to any surgical manipulation; group S (sham) was subjected to surgical manipulation but without ureteral ligation; group UUO was subjected to ureteral obstruction and received no treatment; group UUO + S was subjected to ureteral obstruction and received saline subcutaneously (s.c.) once daily; group UUO + H was subjected to ureteral obstruction and received low molecular weight heparin (LMW-Hep; 4 mg/kg) s.c. once daily; and group C + H was not subjected to any surgical manipulation and received LMW-Hep (4 mg/kg) s.c. once daily. After 14 days, the content of collagen, fibronectin, total glycosaminoglycans (GAGS), chondroitin sulfate/dermatan sulfate proteoglycans (CS/DSPGs), transforming growth factor-beta (TGF-beta) and cellular infiltration were determined in the kidneys by immunohistochemical and biochemical techniques.

RESULTS

Collagen, fibronectin, total GAGS, CS/DSPGs, TGF-beta and cellular infiltration increased significantly in group UUO. LMW-Hep treatment reduced collagen, fibronectin and TGF-beta, but induced an increase in the content of total GAGS, CS/DSPGs and macrophage infiltration in group UUO + H when compared with group UUO.

CONCLUSIONS

LMW-Hep diminishes fibrosis in obstructed kidneys by downregulating the synthesis of collagen, fibronectin and TGF-beta. The mechanisms underlying the overproduction of CS/DSPGs and the increase in cellular infiltration upon LMW-Hep administration remain to be elucidated.

Treatment of proteinuria with low-molecular-weight heparin after renal transplantation

The development of nephrotic-range proteinuria after renal transplantation is an unfavourable prognostic factor for graft survival. In contrast to that in other nephropathies, the role of renin-angiotensin blockade in kidney transplantation is less well defined, and its anti-proteinuric effect is markedly reduced in the presence of segmental glomerulosclerosis. Here, we describe two patients who developed severe proteinuria after renal transplantation, despite effective blood pressure control with an ACE inhibitor. Histological changes were consistent with IgA-nephropathy and focal segmental glomerulosclerosis. Both patients were treated with low-molecular-weight heparin in addition to pre-existing ACE inhibition. This regimen led to a significant and long-lasting reduction of proteinuria. Our data suggest that low-molecular-weight heparin possesses strong renoprotective properties, thus confirming previous data from experimental nephropathies. This approach might represent a promising new strategy for treatment of proteinuria after kidney transplantation.

Preconditioning Strategies to Limit Graft Immunogenicity and Cold Ischemic Organ Injury

During the transplant process, the graft is exposed to numerous events, which may enhance its immunogenicity. In particular, factors related to brain death, such as hemodynamic instability and systemic release of cytokines, cold preservation on harvesting, and reperfusion injury, are known to accumulate in harm, conveying a proinflammatory state to the graft before transplant. Alloimmune reactivity is initiated when the host immune system detects non–self-antigens in the context of “danger signals.” Eliminating these danger signals by modifying the graft before transplant has the potential to attenuate the alloimmune response. The molecules, which mediate danger signals, have not yet been fully identified. Free oxygen radicals and interferon-γ are important candidates. One of the most important protective mechanisms against oxidative stress is the heme oxygenase 1 system. Up-regulation of heme oxygenase 1 in grafts has been shown to prevent ischemia-reperfusion damage and improve long-term graft survival in various transplant models. The benefit of blocking the action of interferon-γ in kidney transplants is less clear because the compound plays such a complex and pivotal role in the immune response, and experimental data with interferon-γ receptor knockout mice are conflicting. It has recently become clear that catecholamines are important graft-modifying agents. Dopamine is capable of stimulating the induction of protective enzymes like heme oxygenase-1 (HO-1) rendering the organ more resistant to the insult of ischemia/reperfusion and inflammation. Retrospective clinical data suggest that treatment of brain-dead organ donors with catecholamines is associated with less rejection and a better long-term graft survival of kidneys transplanted from these donors. Catecholamines can also modulate cytokine production and prevent cold-induced damage. Other substances, such as proteoglycans and phosphatidylethanolamine-bound hyaluronic acid, may interfere with the actions of interferon-γ. Further studies of these compounds in experimental animal models and in prospective randomized clinical trials will help establish their efficacy in donor pretreatment. It is important to underscore that donor pretreatment will have great advantages for the recipient because an improved long-term graft survival could thus be achieved cost-efficiently and without great effort or side effects.

Successful pregnancy with low molecular weight heparin in two women with recurrent miscarriage of unknown etiology

We report here two cases of recurrent miscarriages that were successfully treated with continuous intravenous administration of low molecular weight heparin (LMWH). One patient experienced 11 spontaneous abortions, and the other eight abortions. Previous treatments including prednisone, aspirin and mononuclear-cell immunization were all unsuccessful. They were negative for anticardiolipin antibodies and lupus anticoagulant, and had no inherited thrombophilic disorder. Intravenous administration of LMWH, 4800 units of dalteparin, was started as soon as the conception was confirmed, and was continued until 34 weeks of gestation. They were delivered of live born infants.

High dose of antithrombin III induces indefinite survival of fully allogeneic cardiac grafts and generates regulatory cells

BACKGROUND

The authors investigated whether antithrombin III (AT-III) could induce unresponsiveness to alloantigens.

METHODS

CBA mice were given intravenous injection of 50 or 500 U/kg AT-III or control plasma the same day as transplantation of a heart from a C57BL/6 mouse. An adoptive transfer study and mixed leukocyte culture analysis were also performed.

RESULTS

Naive CBA mice rejected C57BL/6 cardiac grafts acutely (median survival time [MST], 9 days). The 50-U/kg dose of AT-III induced a moderate increase in graft survival (MST, 25 days), whereas control mice rejected their graft acutely (MST, 7 days). With the 500-U/kg dose of AT-III, all grafts survived indefinitely (>100 days) and regulatory cells were generated. In vitro, AT-III suppressed proliferation of mixed leukocyte responses and generation of interleukin-2.

CONCLUSION

AT-III can be not only an antithrombotic agent but also a strong immunomodulating agent when used at high dose.