Erector spinae plane block versus fascia iliaca block after total hip arthroplasty: a randomized clinical trial comparing analgesic effectiveness and motor block

Background

Ultrasound-guided, supra-inguinal fascia iliaca block (FIB) provides effective analgesia after total hip arthroplasty (THA), but is complicated by high rates of motor block. The erector spinae plane block (ESPB) is a promising motor-sparing technique. In this study, we test the analgesic superiority of FIB over ESPB, while also comparing motor impairment.

Methods

In this randomized, observer-blinded clinical trial, patients scheduled for THA with spinal anesthesia were randomly assigned to receive either ultrasound-guided FIB or ESPB preoperatively. Primary outcome was morphine consumption at 24 hours after surgery. Secondary outcomes were: pain scores; assessment of sensory and motor block; incidence of postoperative nausea and vomiting and other complications; and development of chronic post-surgical pain.

Results

Sixty patients completed the study. There were no statistically-significant differences in morphine consumption at 24 hours (p = 0.68) or pain scores at any time point. FIB produced more reliable sensory block in the femoral nerve (p = 0.001) and lateral femoral cutaneous nerve (p = 0.018) distributions. However, quadriceps motor strength was better preserved in the ESPB group when compared to the FIB group (p = 0.002). No differences were observed for hip adduction motor strength (p = 0.253). No differences between groups were observed in terms of side effects or chronic pain incidence.

Consclusions

ESPB may represent a promising alternative to FIB for postoperative analgesia after THA. ESPB and FIB offer similar opioid-sparing benefits within the first day after surgery, but ESPB results in less quadriceps motor impairment.

Complement Alternative Pathway Deficiency in Recipients Protects Kidney Allograft From Ischemia/Reperfusion Injury and Alloreactive T Cell Response

Despite the introduction of novel and more targeted immunosuppressive drugs, the long-term survival of kidney transplants has not improved satisfactorily. Early antigen-independent intragraft inflammation plays a critical role in the initiation of the alloimmune response and impacts long-term graft function. Complement activation is a key player both in ischemia/reperfusion injury (IRI) as well as in adaptive antigraft immune response after kidney transplantation. Since the alternative pathway (AP) amplifies complement activation regardless of the initiation pathways and renal IR injured cells undergo uncontrolled complement activation, we speculated whether selective blockade of AP could be a strategy for prolonging kidney graft survival. Here we showed that Balb/c kidneys transplanted in factor b deficient C57 mice underwent reduced IRI and diminished T cell-mediated rejection. In in vitro studies, we found that fb deficiency in T cells and dendritic cells conferred intrinsic impaired alloreactive/allostimulatory functions, respectively, both in direct and indirect pathways of alloantigen presentation. By administering anti-fB antibody to C57 wt recipients in the early post Balb/c kidney transplant phases, we documented that inhibition of AP during both ischemia/reperfusion and early adaptive immune response is necessary for prolonging graft survival. These findings may have implication for the use of AP inhibitors in clinical kidney transplantation.

AAV9-mediated engineering of autotransplanted kidney of non-human primates

Ex vivo gene transfer to the graft before transplantation is an attractive option for circumventing systemic side effects of chronic antirejection therapy. Gene delivery of the immunomodulatory protein cytotoxic T-lymphocyte-associated protein 4-immunoglobulin (CTLA4-Ig) prevented chronic kidney rejection in a rat model of allotransplantation without the need for systemic immunosuppression. Here we generated adeno-associated virus type 2 (AAV2) and AAV9 vectors encoding for LEA29Y, an optimized version of CTLA4-Ig. Both LEA29Y vectors were equally efficient for reducing T-cell proliferation in vitro. Serotype 9 was chosen for in vivo experiments owing to a lower frequency of preformed antibodies against the AAV9 capsid in 16 non-human primate tested sera. AAV9-LEA29Y was able to transduce the kidney of non-human primates in an autotransplantation model. Expression of LEA29Y mRNA by renal cells translated into the production of the corresponding protein, which was confined to the graft but not detected in serum. Results in non-human primates represent a step forward in maintaining the portability of this strategy into clinics.

Time course of cytokines, hemodynamic and metabolic parameters during hyperthermic intraperitoneal chemotherapy

INTRODUCTION

Systemic response to cytoreductive surgery (CRS) and hyperthermic intraperitoneal chemotherapy (HIPEC) causes the activation of endocrine, metabolic, hemodynamic and inflammatory processes. The aim of this work is to describe and analyze the time course of the inflammatory markers concentration during CRS+HIPEC in plasma and peritoneal fluids and the association with hemodynamic and metabolic parameters.

MATERIAL AND METHODS

Pre-, Intra- and Post-operative data were collected. Tumor necrosis factor (TNF), interleukine 6, procalcitonine (PCT), cancer antigen 125 (CA-125) in blood and in peritoneal fluids were evaluated.

RESULTS

Thirty-eight patients included, 29 (76.3%) female. Mean/median PCI: 9.2/5. Primary malignancy: 5 colo-rectal (13.2%), 5 gastric (13.2%), 23 ovarian (60.5%) and 5 others (13.2%). CCR 0-1 reached in all patients. Cardiac Index, Heart rate and Central Venous Pressure, increased during the procedure while Stroke Volume Variation showed a decrease. Mean Arterial Pressure and Superior Vena Cava Oxygenation were stable through the whole procedure. TNF and CA-125 were steady during the whole procedure; IL-6 had a relevant increase from baseline to start of perfusion (p<0.01); PCT had a steady increase at every time point. Peritoneal sampling showed a statistically significant increase (p<0.01) between start and end of the perfusion phase for all markers but TNF. Serum and peritoneal marker concentration were similar for TNF, PCT and CA-125. IL-6 showed a sharp difference.

CONCLUSION

The most significant variations are those of IL-6 and PCT. The cytokines level parallel the hemodynamic derangements. Treatment during HIPEC should mimic the established treatment during sepsis and septic shock.

An unanticipated role for survivin in organ transplant damage

Ischemia/reperfusion (I/R) injury is a major determinant of graft survival in kidney transplantation. Survivin, an inhibitor of apoptosis that participates in the control of mitosis and cell cycle progression, has been implicated in renal protection and repair after I/R injury; however, no study has been performed in the transplant setting. We investigated the role of survivin in modulating posttransplant I/R injury in syngeneic and allogeneic kidney grafts, and studied whether protection from I/R injury impacted on the recipient immune system, on chronic allograft nephropathy and rejection. We used genetically engineered mice with survivin haploinsufficiency and WT mice in which survivin over-expression was induced by gene-delivery. Survivin haploinsufficiency in syngeneic grafts was associated with exuberant I/R tissue injury, which triggered inflammation eventually resulting in graft loss. Conversely, survivin over-expression in the grafts minimized I/R injury and dysfunction in syngeneic grafts and in a clinically relevant fully MHC-mismatched allogeneic combination. In the latter, survivin over-expression translated into limited anti-donor adaptive immune response and less long-term allograft injury with protection from renal parenchymal damage. Our data support survivin over-expression in the graft as a novel target for protocols aimed at limiting tissue damage at the time of transplant ultimately modulating the recipient immune system.

A novel strategy to enhance mesenchymal stem cell migration capacity and promote tissue repair in an injury specific fashion

Mesenchymal stem cells (MSCs) of bone marrow origin appear to be an attractive candidate for cell-based therapies. However, the major barrier to the effective implementation of MSC-based therapies is the lack of specific homing of exogenously infused cells and overall the inability to drive them to the diseased or damaged tissue. In order to circumvent these limitations, we developed a preconditioning strategy to optimize MSC migration efficiency and potentiate their beneficial effect at the site of injury. Initially, we screened different molecules by using an in vitro injury-migration setting, and subsequently, we evaluated the effectiveness of the different strategies in mice with acute kidney injury (AKI). Our results showed that preconditioning of MSCs with IGF-1 before infusion improved cell migration capacity and restored normal renal function after AKI. The present study demonstrates that promoting migration of MSCs could increase their therapeutic potential and indicates a new therapeutic paradigm for organ repair.

The impact of perioperative transfusion of blood products on survival after pediatric liver transplantation

Intraoperative transfusion of red blood cells (RBC) is associated with adverse outcome after LT in adult patients. This relationship in pediatric patients has not been studied in depth, and its analysis is the scope of this study. Forty-one variables associated with outcome, including blood product transfusions, were studied in a cohort of 243 pediatric patients undergoing a cadaveric LT between 2002 and 2009 at the General Hospital of Bergamo. Multivariate stepwise Cox proportional hazards models were adopted with adjustment by propensity scores to minimize factors associated with the use of blood products. Median age at transplant was 1.37 yr. In uni- and multivariate analyses, perioperative transfusion of FFP and RBC was an independent risk factor for predicting one-yr patient and graft survival. The effect on one-yr survival was dose-related with a hazard ratio of 3.15 for three or more units of RBC (p = 0.033) and 3.35 for three or more units of FFP (p = 0.021) when compared with 1 or no units transfused. The negative impact of RBC and FFP transfusion was confirmed by propensity score-adjusted analysis. These findings may have important implications for transfusion practice in the LT pediatric recipients.

Adenoviral-mediated gene transfer restores plasma ADAMTS13 antigen and activity in ADAMTS13 knockout mice

ADAMTS13 is a plasma metalloprotease that regulates the size of the von Willebrand factor (VWF) multimers. Genetic or acquired deficiency of ADAMTS13 causes thrombotic thrombocytopenic purpura (TTP) in humans. Plasma infusion is the treatment of choice for patients with congenital ADAMTS13 deficiency. However, this practice exposes patients to the risk of infections, allergies and fluid volume overload. The search for alternative treatments is required. Here, we tested the ability of systemically administered adenovirus encoding human ADAMTS13 to restore the deficient protein in the circulation of Adamts13(-/-) mice. Injection of the adenovirus efficiently transduced the liver, kidney, lung, heart and spleen, resulting in the secretion of ADAMTS13 into plasma. A reduced area of thrombi was observed when blood from Ad-ADAMTS13-treated mice was perfused over a collagen-coated surface in a parallel plate flow chamber compared with blood of Ad-betaGal-treated controls. The secreted ADAMTS13 protein was functionally active even after 2 months from injection. The data provide the proof of principle for developing a novel therapy for the correction of ADAMTS13 deficiency in patients with hereditary TTP.

Endothelin receptor selectivity in chronic renal failure

Chronic kidney diseases are increasing worldwide at an alarming rate, and they are emerging as a major public health problem. Treatments that slow the progression of chronic kidney disease are needed. Endothelin-1 (ET-1) is a potent vasoconstrictor with proinflammatory, mitogenic and profibrotic effects that is closely involved in both normal renal physiology and pathology. Increasing evidence suggests that ET-1 and its cognate receptors are involved in a variety of progressive renal disorders to the extent that renal ET-1 expression correlates with disease severity and renal function impairment. Endothelin receptor antagonists have been used in renoprotection studies owing to their capacity of improving renal hemodynamics and reducing proteinuria. Whether selective ET(A) or non-selective ET(A)/ET(B) receptor antagonists are preferable is still a matter of debate. As angiotensin II blockers are not invariably effective in retarding disease progression when treatment is started late in the course of the disease, it is foreseeable that an ET-1 antagonist in addition to angiotensin-converting enzyme inhibitors could represent a combined treatment for progressive nephropathies. The focus of this review is to examine the role endothelin-1 plays in kidney diseases and to determine the ideal setting for antagonizing its biological activity in chronic nephropathies.

The use of desflurane or propofol in combination with remifentanil in myasthenic patients undergoing a video-assisted thoracoscopic-extended thymectomy

BACKGROUND

Although several studies of the use of desflurane in anesthesia have revealed many desirable qualities, there are no data on the use and effects especially on the neuromuscular function of desflurane on myasthenia gravis (MG) patients. The purpose of this study was to evaluate the use of either desflurane or propofol, both combined with remifentanil, in patients with MG undergoing a video-assisted thoracoscopic-extended thymectomy (VATET).

METHODS

Thirty-six MG patients who underwent VATET were enrolled. Nineteen patients were anesthetized with remifentanil and propofol infused with a target-controlled infusion plasma model, and 17 patients with desflurane and remifentanil. No muscle relaxant was used. The intubating conditions, hemodynamic and respiratory changes, neuromuscular transmission and post-operative complications were evaluated.

RESULTS

Neuromuscular transmission was significantly decreased in the desflurane group (6.7%, from 3% to 9% during anesthesia P=or<0.05). The intubating conditions were good in all 36 patients and 35 patients were successfully extubated in the operating room. The time-to-awakening, post-operatory pH and base excess were significantly different in the two groups, with a decreasing mean arterial pressure in the group administered with desflurane. No patients required reintubation due to myasthenic or cholinergic crisis, or respiratory failure. No other significant differences between the two groups studied were observed.

CONCLUSION

Our experience indicates that anesthesia with desflurane plus remifentanil in patients with MG could determine a reversible muscle relaxation effect, but with no clinical implication, allowing a faster recovery with no difference in extubation time and post-operative complications in the two groups.

ACE inhibition reduces glomerulosclerosis and regenerates glomerular tissue in a model of progressive renal disease

Today angiotensin II inhibition is primarily used to slow the rate of progression of kidney diseases. There is evidence that these therapies can induce a partial regression of glomerular lesions. However, we do not know yet the extent of sclerotic lesion regression and whether new glomerular tissue is formed to help support the renal function. We used male Munich Wistar Fromter (MWF) rats, an experimental model for progressive kidney disease, to quantify kidney structural lesions upon angiotensin-converting enzyme (ACE) inhibition therapy. Animals were studied at 50 weeks of age, when renal function and structure are severely altered, and after a 10-week observation period, without or with treatment with lisinopril (80 mg/l in drinking water). A group of untreated Wistar rats was used as controls. With age, proteinuria, and serum creatinine worsen, but lisinopril almost normalized proteinuria and stabilized serum creatinine. Serial section analysis of whole glomerular tufts showed that at baseline, glomerulosclerosis affected the entire glomerular population, and that these changes further increased with age. Lisinopril significantly reduced incidence and extent of glomerulosclerosis, with the presence of glomerular tufts not affected by sclerosis (23% of glomeruli). Glomerular volume was not significantly affected by treatment, and glomerular mass spared from sclerosis increased from 46.9 to 65.5% upon treatment, indicating consistent regeneration of glomerular tissue. Lisinopril normalized baseline glomerular transforming growth factor-beta and alpha-smooth muscle actin overexpression, and prevented worsening of interstitial changes. Hence, ACE inhibition, which is widely used in human kidney disease, may not only halt the progression of renal failure, but also actually induce the regeneration of new renal tissue.

Gene therapy: how to target the kidney. Promises and pitfalls

The success of gene therapy strongly depends on an efficient delivery system to allow local transfer and expression of the therapeutic gene in the target organ or tissue. Vector systems have been improved and many show promise. There are two different categories of delivery vehicles: non-viral and viral vectors, both with advantages and disadvantages that must be taken into consideration in view of the final aim. Compared to other solid organs, the kidney offers the main advantage of access by different routes that dictate different sites of transfection. Thus, the choice of the delivery vehicle and administration route has to take account which cells are to be specifically targeted by the gene transfer approach. This concept will be discussed in the first part of the review. Using a gene therapy approach, improvements of renal function and interstitial inflammation have been achieved in experimental models of glomerulonephritis and tubulo-interstitial damage. Gene therapy applied to renal transplantation has shown promising results in rodents, almost controlling acute rejection. Finally, the development of animal models resembling the clinical features of human genetic renal disorders offers a first step towards new treatments among which gene therapy could become reality in the near future. The main findings concerning the suitability of gene therapy for slowing the progression of kidney diseases, and preventing acute renal graft rejection, or treating genetic disorders, are discussed.

Angiotensin-converting enzyme inhibition prevents glomerular-tubule disconnection and atrophy in passive Heymann nephritis, an effect not observed with a calcium antagonist

In proteinuric nephropathies tubular atrophy leads to glomerular-tubule disconnection through an unknown mechanism. Here we studied whether proteinuria promoted glomerular-tubule disconnection in individual nephrons and whether this phenomenon was prevented by an angiotensin-converting enzyme (ACE) inhibitor. Passive Heymann nephritis (PHN) and control rats were studied at 4 and 8 months. Two additional groups of PHN rats received lisinopril (40 mg/L) or a calcium channel blocker (lacidipine, 3 mg/kg) from day 7 after surgery to 8 months. At sacrifice, kidneys were serially sectioned to identify glomerular- tubule abnormalities in individual nephrons and changes in interstitial volume. In PHN rats, the time-dependent increase in proteinuria was paralleled by tubular atrophy leading to glomerular-tubule disconnection and interstitial volume enlargement. Marked apoptosis was invariably found in atrophic tubules in contrast to the absent or very mild terminal dUTP nick-end labeling staining in tubules normally connected to glomeruli in PHN animals. Treatment with an ACE inhibitor prevented hypertension, proteinuria, the formation of atrophic tubuli, glomerular-tubule disconnection and limited the fractional interstitial volume expansion. Although lacidipine limited hypertension, it did not reduce proteinuria or prevent tubular atrophy and disconnection. Multivariate analysis showed that the appearance of atubular glomeruli and the increase in interstitial volume were better predicted by proteinuria than blood pressure. This study suggests that ACE inhibitors effectively prevent glomerular-tubule disconnection possibly by their ability of reducing proteinuria, which in turn favors proximal tubular cell apoptosis. Agents that only reduced hypertension but not proteinuria do not affect tubular behavior.

Mycophenolate mofetil combined with a cyclooxygenase-2 inhibitor ameliorates murine lupus nephritis

BACKGROUND

Approaches to the treatment of lupus nephritis include immunosuppressants associated with anti-inflammatory drugs, mainly steroids, which, however, cause major side effects. Mycophenolate mofetil (MMF) has been described as being less toxic than conventional immunosuppressants, and it was effective in preventing progressive nephritis in lupus mice. Our study evaluated the therapeutic effect of MMF in NZB/W F1 hybrid mice with established disease. We also examined the combination of MMF with a selective cyclooxygenase-2 (COX-2) inhibitor, DFU, based on previous findings of excessive renal production of COX-2-derived thromboxane A2 (TXA2) in lupus nephritis.

METHODS

Four groups of NZB/W mice (N = 30 each group), starting at five months of age, were given daily by gavage the following: vehicle, MMF 60 mg/kg, DFU 3 mg/kg, or MMF + DFU. Fifteen mice for each group were used for the survival studies, and the remaining mice were sacrificed at nine months.

RESULTS

MMF or DFU alone partially delayed the onset of proteinuria compared with vehicle. Combined therapy was significantly (P < 0.05) more effective than single drugs. Animal survival was partially ameliorated by MMF and significantly improved by the drug combination in comparison with the vehicle (P = 0.005) and DFU alone (P < 0.03). At nine months, serum blood urea nitrogen (BUN) levels were lower in all of the treated groups than in the vehicle group. Renal damage was also limited, but to a greater extent in mice given the combined therapy. In untreated mice, renal COX-2 mRNA expression was up-regulated, and generation of TXB(2), the stable breakdown product of TXA(2), increased. DFU prevented the abnormal renal TXB(2) production, confirming the COX-2 origin of this eicosanoid, whereas renal 6-keto-PGF(1 alpha) and prostaglandin E(2) (PGE(2)) were not affected substantially.

CONCLUSIONS

These results offer a strong case for exploring the possibility that in humans MMF combined with COX-2 inhibitors has a role in the treatment options for lupus nephritis. This combined drug therapy may be at least as effective as steroids but without the obvious nephrotoxicity of the latter.

Endothelin antagonists and renal protection

Proteinuric nephropathies either of diabetic or nondiabetic origin tend to develop renal structural damage associated with progressive renal function decline over time. In proteinuric glomerular disease excessive protein reabsorption by proximal tubular epithelial cells modulates tubular cell function to the extent that cell growth and their phenotypic expression of growth factors and inflammatory chemokines and cytokines is upregulated. Recent evidence is available that renal tubular cells synthesize endothelins (ETs), a family of peptides with potent vasoconstrictor and proliferation properties, and that overloading these cells with proteins induces a dose-dependent increase in the synthesis and release of ET-1. This peptide, accumulating in the renal interstitium, eventually participates in activation of the sequence of events that leads to interstitial inflammation and ultimately renal scarring. Increased renal synthesis of ET-1 occurs in vivo as documented in several animal models of proteinuric progressive nephropathies, in which enhanced renal ET-1 gene expression as well as the excretion of the peptide in the urine correlated with the urinary protein excretion rate. Similarly, in patients with chronic renal disease an association has been found between increased urinary excretion of ET-1 and renal damage. A strong argument in favor of ET-1 as a mediator of renal injury derives from preclinical studies with selective and non-selective ET receptor antagonists that have became available in the past few years. They block the effect of ET to their specific receptors called ET(A) and ET(B), and have been reported to have a renoprotective effect in several animal models of progressive renal disease, including in rats with remnant kidney or experimental diabetes as well as mice with lupus nephritis. The peptide nature of some of these compounds, which are currently appearing in the literature, may however hamper their future use in humans. Administration of nonpeptide ET receptor antagonists to humans would hopefully overcome this problem and possibly provide a new therapeutic approach for patients with renal disease who do not adequately respond to the currently available therapy with angiotensin-converting enzyme inhibitors or angiotensin II receptor antagonists.

Research on renal endothelin in proteinuric nephropathies dictates novel strategies to prevent progression

Proteinuria is one of the major risk factors for renal disease progression in patients with chronic nephropathies. Studies in disease models have helped to delineate mechanisms leading to renal structural damage as a result of persistent dysfunction of the glomerular barrier to proteins, even when the primary immune or non-immune insult to the kidney has ceased. From these preclinical studies, a role for endothelin in proteinuric chronic renal diseases has been suggested, thus providing the rationale for novel therapeutic approaches with endothelin receptor antagonists to maximize renoprotection so far achieved with blockade of the renin-angiotensin system by angiotensin-converting enzyme inhibition or angiotensin II receptor antagonism. Trials are needed to explore this potential area of clinical interest.

How renal cytokines and growth factors contribute to renal disease progression

Terminal renal failure is the final common fate of chronic nephropathies regardless of the type of original insult. After removal of a critical number of nephrons, adaptive hemodynamic changes in the remaining nephrons ensure enough filtration power to the kidney but are ultimately detrimental. Such changes are largely mediated by the local formation of angiotensin II (AII) and prevented by the use of angiotensin-converting enzyme inhibitors, which also limit the forced opening of large unselective pores in the glomerular barrier, restoring size selectivity. Recent studies suggested that proteins filtered through the glomerular capillary, previously considered a marker of the severity of renal lesions, might have intrinsic toxicity on the proximal tubular cells and a contributory role in the progression of renal damage. Protein overload of proximal tubular cells induced the secretion of endothelin-1 (ET-1), monocyte chemoattractant protein-1 (MCP-1), and regulated on activation, normal T expressed and secreted (RANTES) that was mainly directed toward the basolateral compartment of the cell. Evidence available in rat models of proteinuric renal disease shows that expression of genes encoding such vasoactive and proinflammatory molecules as ET-1, MCP-1, and RANTES was consistently upregulated, and synthesis of the corresponding peptides was enhanced in renal tissue. Additional mechanisms of proximal tubular cell activation leading to interstitial inflammation and matrix deposition are the filtration of protein-bound metals and hormones and deposition and activation of filtered complement. Limiting protein traffic and the biological effect of excessive tubular protein reabsorption by drugs interfering with AII synthesis or biological activity prevents renal disease progression.

Protein traffic activates NF-kB gene signaling and promotes MCP-1-dependent interstitial inflammation

Mononuclear cells accumulate in the renal interstitium and contribute to renal injury in proteinuric nephropathies. Angiotensin-converting enzyme (ACE) inhibitors reduce protein trafficking and also lessen renal structural and functional damage. Many proinflammatory genes, including monocyte chemoattractant protein-1 (MCP-1), a chemoattractant for monocytes and T lymphocytes, are transcriptionally regulated by nuclear factor-kappa B (NF-kB). We aimed to study NF-kB activation and MCP-1 expression over time in two models of progressive proteinuric nephropathies (5/6 nephrectomy and passive Heymann nephritis [PHN]) and evaluate the effect of antiproteinuric therapy with an ACE inhibitor on these factors. In both models, increased urinary protein excretion over time was associated with a remarkable increase in NF-kB activity, which was almost completely suppressed by reducing proteinuria with lisinopril. NF-kB activation was paralleled by upregulation of MCP-1 messenger RNA and interstitial accumulation of ED-1-positive monocytes/macrophages and CD8-positive T cells. Lisinopril inhibited MCP-1 upregulation and limited interstitial inflammation. In a group of PHN rats with advanced disease and severe proteinuria, a dose of lisinopril high enough to inhibit renal ACE activity failed to reduce proteinuria and also did not limit NF-kB activation, which was sustained over time, along with MCP-1 gene overexpression and interstitial inflammation. These data suggest that NF-kB is activated in the presence of increased protein traffic, enhancing the nuclear transcription of the MCP-1 gene with potent chemotactic and inflammatory properties. This mechanism may help explain the long-term renal toxicity of filtered proteins.

A novel interpretation of the role of von Willebrand factor in thrombotic microangiopathies based on platelet adhesion studies at high shear rate flow

Clinical manifestations of thrombotic microangiopathies (TMA) are secondary to platelet aggregation and thrombotic occlusion of the microvasculature of the affected organs. Abnormalities in von Willebrand factor (vWF) in these patients were considered instrumental in promoting the process leading to microvascular thrombosis. We evaluated the capacity of plasma in these patients to induce adhesion of normal platelets and thrombus formation under conditions of controlled fluid shear stress. We also studied vWF multimeric distribution to establish whether abnormalities of this glycoprotein correlate with platelet adhesion and thrombus formation. Plasma from patients in the acute phase and remission showed the same capacity to induce platelet adhesion and thrombus formation at a low level of shear rate (600 sec(-1)) as plasma from control subjects. At a high shear rate (1,500 sec(-1)), platelet adhesion and thrombus dimensions were significantly increased (P: < 0.05) by plasma from patients with TMA compared with controls. The capacity to enhance thrombus formation at high shear stress was present during the acute phase and disease remission and did not correlate with the presence of unusually large vWF multimers. Increased thrombus formation with patient plasma is completely normalized by blocking the interaction of vWF with the platelet receptors, glycoprotein (GP)Ib and GPIIb-IIIa, suggesting that the phenomenon is completely mediated by vWF. Our results suggest the possibility of an intrinsically altered vWF molecule in these patients that is probably more effective than normal vWF in mediating platelet adhesion and thrombus formation.

Nonviral and viral gene transfer to the kidney in the context of transplantation

BACKGROUND/AIMS

Local modulation of the immune response through genetic manipulation of the graft is an attractive novel approach to overcome the toxicity of immunosuppressive therapy to prevent acute graft rejection. We have previously reported that the cationic polymer polyethylenimine 25k (PEI 25k) transduced reporter genes when injected into the renal artery, but with a low transfection efficiency. Here we compare the risk/benefit profiles of such a nonviral versus a viral technique of gene transfer to the kidney in the context of renal transplantation.

METHODS

Donor kidneys from Lewis rats were perfused in a closed circuit with an artificial cell-free medium containing PEI 25k complexed to an expression vector coding for the beta-galactosidase (beta-gal) gene and subsequently transplanted in a syngeneic animal. In a second set of experiments, donor kidneys were injected or perfused with a replication-deficient adenovirus encoding the beta-gal gene (AdCMV. beta-gal; 1 x 10(9) plaque-forming units) before transplantation.

RESULTS

Perfusion of the kidney with PEI 25k/DNA complexes resulted in large areas of hypoperfusion characterized by injured glomeruli and tubuli, capillary thrombosis and accumulation of C3 in glomerular capillaries. Reperfusion of the kidney was achieved by lowering the PEI 25k/DNA ratio, but no detectable transfection was observed. In animals receiving adenovirus, the beta-gal activity increased with time and was localized mainly in proximal and distal tubular cells, as documented by beta-gal histochemistry and in situ hybridization. A significantly increased expression of beta-gal was achieved by perfusion of the kidney with AdCMV.beta-gal before transplantation, beta-gal staining mainly localizing in proximal and distal tubular cells.

CONCLUSIONS

Unlike nonviral methods of gene delivery, adenovirus-mediated gene transfer to the kidney offers exciting perspectives for the development of molecular medicine in the field of organ transplantation.

Protein overload activates proximal tubular cells to release vasoactive and inflammatory mediators

Chronic renal diseases with highly enhanced glomerular permeability to proteins are accompanied by tubulointerstitial inflammation and scarring and progression to renal failure. As a consequence of increased glomerular permeability, proteins filtered through the glomerular capillary in excessive amount have intrinsic renal toxicity at least partially linked to their accumulation in the proximal tubular cell cytoplasm during the process of reabsorption along the nephron. Experimental evidence is available showing that protein overload per se activates proximal tubular epithelial cells in culture to upregulate genes encoding for endothelin, chemokines and cytokines. These vasoactive and inflammatory substances, formed in excessive quantities by the tubular cells, are released mainly into the basolateral compartment, a pattern of secretion that in the kidney would favor recruitment and activation of inflammatory cells into the renal interstitium and fibrogenic reaction leading to renal scarring.

Combining an antiproteinuric approach with mycophenolate mofetil fully suppresses progressive nephropathy of experimental animals

Chronic renal diseases progress to organ insufficiency, which may require replacement therapy within one to three decades even independently of the type of initial insults. In the majority of cases, the degrees of proteinuria and interstitial leukocyte infiltration and scarring are strictly correlated with the rate of disease progression. This study tests the hypothesis that excess intrarenal protein traffic may cause lymphocyte-dependent interstitial injury that, while not fully controlled by antiproteinuric therapy, can be further inhibited by concomitant immunosuppression. A primarily nonimmune model was used to reproduce progressive renal disease due to a critical loss of nephron mass. Angiotensin-converting enzyme (ACE) inhibitor limited proteinuria, interstitial inflammation, MHC class II antigen expression, and severe lesions. Combined treatment with ACE inhibitor and a specific antilymphocyte agent, mycophenolate mofetil, dramatically attenuated macrophage and T cell infiltration, MHC-class II overexpression, dendritic cells, and all manifestations of the disease. Evidence of lymphocyte-mediated renal injury in the setting of excess protein traffic provides the basis for combining ACE inhibition and immunosuppression to halt progression of proteinuric kidney disease and minimize the need for dialysis or transplantation.

Unrecognized pattern of von Willebrand factor abnormalities in hemolytic uremic syndrome and thrombotic thrombocytopenic purpura

Heterogeneous abnormalities in multimeric structure and fragmentation of endothelial-derived von Willebrand factor (vWF) have been reported in hemolytic uremic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP). This study was conducted to establish whether different patterns of vWF abnormalities were associated with different clinical syndromes. Plasmatic levels of vWF antigen (vWF:Ag), vWF release from endothelial cells (EC) exposed to patient sera, and vWF multimeric pattern were studied during episodes and again in remission in three groups of patients with severe forms of HUS and TTP paradigmatic of the most common clinical patterns of disease presentation: (1) plasma-responsive; (2) plasma-resistant; and (3) frequently relapsing. Plasma vWF:Ag and serum-induced vWF release from EC were increased in the acute phase of either plasma-responsive and plasma-resistant HUS and TTP, but normalized at remission only in plasma-responsive cases. Both indices were persistently normal in the relapsing forms. Enhanced vWF fragmentation as defined by disappearance of high molecular weight and increase in low molecular weight forms was a consistent finding of the acute phases, and always normalized in remission in all three groups. Unusually large vWF multimers were found exclusively in plasma of relapsing forms of HUS and TTP both during and between relapses. Enhanced levels of vWF:Ag and serum capability to induce vWF release in vitro are markers of disease activity and may reflect systemic endothelial injury and consequent activation. Their presence discriminates acute single-episode cases from relapsing forms and, when failing to normalize with plasma therapy, predicts plasma resistance. Enhanced low molecular weight multimers that closely paralleled disease activity suggest a permissive role of fragmented vWF in the formation of microvascular thrombi. Finally, finding of unusually large multimers exclusively in relapsing forms of HUS and TTP even between relapses, when no other clinical signs of disease activity could be detected, suggests that they cannot be the only factor in microvascular thrombosis.

Renoprotection by nitric oxide donor and lisinopril in the remnant kidney model

Previous studies showed a renoprotective effect of l-arginine in experimental uremia. Whether this was caused by an increased nitric oxide (NO) release or depended on l-arginine per se is not clear. Here, we evaluated whether chronic administration of an NO donor, molsidomine, controlled systemic blood pressure and renal disease progression and prolonged survival in rats with renal mass reduction (RMR). Rats with RMR received the following daily in the drinking water: group 1 (n = 21), no specific therapy (vehicle); group 2 (n = 12), molsidomine, 120 mg/L; group 3 (n = 9), lisinopril, 25 mg/L; and group 4 (n = 12), reserpine, 5 mg/L, hydralazine, 80 mg/L, and hydrochlorothiazide, 25 mg/L, from day 21 after surgery, when rats had hypertension and proteinuria, until the death of the vehicle-treated rats. Molsidomine normalized systemic hypertension, only partially reduced proteinuria and serum creatinine levels, but significantly prolonged animal survival, particularly in the early stage of the disease. Lisinopril at a similar systemic blood pressure was even better than molsidomine in limiting proteinuria, preserving renal function, and prolonging survival, but triple therapy, despite being effective on blood pressure, offered no renoprotection or prolonged survival. Endothelin-1 (ET-1) levels, formed in excessive amounts by the kidneys of these animals, were reduced by molsidomine and lisinopril, but not by triple therapy. The prolongation of survival by NO donor could be attributed to its effect of reducing ET levels, which in turn may limit the smooth muscle cell proliferation and matrix accumulation responsible for organ and, especially, myocardial fibrosis in uremia.

Nature and mediators of renal lesions in kidney transplant patients given cyclosporine for more than one year

BACKGROUND

Cyclosporine (CSA) has improved patients and organ-graft survival rates, but its chronic nephrotoxicity is still an issue. Although prolonged vasoconstriction could contribute to chronic CsA tubulointerstitial changes by producing chronic ischemia, this relationship has been difficult to demonstrate thus far, and cellular origin and mediators of these structural alterations remain ill-defined.

METHODS

As a part of a clinical trial in kidney transplant recipients on triple immunosuppressive therapy (CsA, azathioprine and steroid), which includes renal biopsy as "per protocol," 22 patients enrolled between 12 and 24 months posttransplantation underwent renal hemodynamic evaluation by measuring glomerular filtration rate and renal plasma flow by the plasma clearance of unlabeled iohexol and the renal clearance of para-aminohippuric acid, respectively. In parallel, the CsA pharmacokinetic profile was also determined. A week later, a protocol biopsy of kidney graft was performed. Light microscopy examination and localization of endothelin-1, RANTES, monocyte chemoattractant protein-1 gene expression by in situ hybridization in the graft specimens were evaluated and related to the pattern of histologic lesions.

RESULTS

Ten out of 22 kidney transplant recipients who underwent the protocol biopsy had CsA nephrotoxicity, eight had chronic rejection, and four had no lesions at histological examination. The total daily exposure to CsA was higher in patients with CsA nephrotoxicity than in those with chronic rejection or no lesions at biopsy. Renal function was preserved in the CsA toxicity group as compared with the chronic rejection group, despite some degree of renal hypoperfusion. Tubular atrophy and striped interstitial fibrosis were found in all patients with light microscopical evidence of CsA nephrotoxicity, whereas glomerular and arteriolar lesions were less frequent. Intense staining for endothelin-1, RANTES, and monocyte chemoattractant protein-1 mRNAs selectively localized at tubular epithelial cells was found in biopsies taken from patients with CsA nephrotoxicity, but not in the chronic graft rejection group, whose tubuli had only minimal staining for RANTES mRNA on a few occasions.

CONCLUSION

Long-term CsA administration to kidney allograft recipients leads to tubulointerstitial injury independently of its vascular effect. The possible contribution to the development of interstitial fibrosis of inflammatory and growth factors released by tubular cells in which CsA accumulates is proposed.

Endothelin antagonists

The very potent endogenous vasoconstrictor endothelin was discovered in 1988. We know now that there are three isoforms (1, 2, and 3) and two receptor subtypes (A and B). A whole range of peptide and non-peptide antagonists has been developed, some selective for A or B receptors and others with non-selective A/B antagonistic activity. So far the main application of these agents has been experimental--ie, endothelin blockers are used to throw light on disease mechanisms, most notably cardiovascular and renal. However, the non-selective antagonist bosentan and a few other agents have been studied clinically. Evidence so far from preclinical studies and healthy volunteers and from the limited number of investigations in patients permits a listing of the potential areas of clinical interest. These are mainly cardiovascular (eg, hypertension, cerebrovascular damage, and possibly heart failure) and renal. Clouds on the horizon are the need to show that these new agents are better than existing drugs; the possibility of conflicting actions if mixed A/B antagonists are used; and animal evidence hinting that endothelin blockade during development could be dangerous.

Mechanism of progression of renal disease: growth factors and related mechanisms

Several studies have consistently indicated a close association between altered glomerular permeability to proteins and renal damage. Dietary and pharmacologic manipulations that restore the selectivity of the glomerular barrier to macromolecules stop progressive renal injury. We propose that abnormal traffic of proteins through the glomerular capillary has an intrinsic renal toxicity because of protein over-reabsorption by proximal tubular cells. Protein overload induces functional alterations of tubular cells, including overexpression of vasoactive and proinflammatory mediators such as endothelin-1. This review examines the role of endothelin-1 as a trigger of renal damage, both in vitro and in vivo, and summarizes relevant supporting data.

Renoprotective effect of contemporary blocking of angiotensin II and endothelin-1 in rats with membranous nephropathy

BACKGROUND

We previously showed that chronic administration of an angiotensin converting enzyme (ACE) inhibitor to rats with passive Heymann nephritis (PHN), a model of membranous nephropathy with proteinuria and increased renal synthesis of endothelin-1 (ET-1), reduces urinary proteins and partially limits the exaggerated ET-1 renal synthesis. Here we compared the effect of an ETA receptor antagonist and an ACE-inhibitor given as single therapies with a combination of the two drugs in uninephrectomized PHN rats.

METHODS

PHN was induced with a single i.v. injection of rabbit anti-Fx1A antibody in 40 male Sprague Dawley rats. To accelerate the onset of renal damage rats underwent uninephrectomy seven days later and were subsequently treated until eight months with the ETA receptor antagonist LU-135252 (50 mg/kg b.i.d. p.o.) or the ACE-inhibitor trandolapril (1 mg/kg in the drinking water) or the combination of the two drugs.

RESULTS

Either LU-135252 or trandolapril given alone prevented the increase in systolic blood pressure (SBP). Combined therapy was even more effective than single drugs. While LU-135252 and trandolapril reduced proteinuria by 23 to 25%, the drug combination resulted in 45% lowering of urinary proteins. Serum creatinine was significantly decreased by the combination, but not by the single drugs. Glomerulosclerosis and tubulointerstitial damage were more reduced by combined therapy than by LU-135252 or trandolapril alone.

CONCLUSIONS

These data suggest that contemporary blocking angiotensin II (Ang II) and ET-1 in an accelerated model of PHN had an additive renoprotective effect than single blocking Ang II or ET-1 and would represent a therapeutic advantage for renal disease patients who do not completely respond to ACE inhibitors.

Upregulation of renal and systemic cyclooxygenase-2 in patients with active lupus nephritis

In lupus nephritis (LN), renal thromboxane A2 (TXA2) production is increased, and inhibition of TXA2 activity improves renal function. In patients with LN, renal function depends very much on vasodilatory prostaglandins, and indeed inhibiting the prostaglandin-forming enzyme cyclooxygenase (COX) with aspirin or related compounds was detrimental on renal hemodynamics in these patients. There are no data so far on whether the excessive TXA2 production in LN derives from upregulation of type I or type II isoforms of COX. It was found that TXB2 synthesis and COX-2 gene expression were higher in peripheral blood mononuclear cells from patients with active LN compared to patients in the inactive form of the disease and to healthy subjects. Unlike COX-2, levels of COX-1 mRNA were comparable in lupus patients and control subjects and were not influenced by the disease activity. Immunoperoxidase studies on kidney biopsies showed COX-1 staining in glomerular arterioles and other renal vessels, with no evident difference between lupus biopsies and control specimens taken from either individuals who were free of renal disease or patients with non-lupus nephropathies. In contrast, COX-2 staining was definitely stronger in specimens from patients with active LN than control specimens. In active LN, COX-2-specific staining was localized mainly in the glomeruli, with a weaker signal on tubuli and in the interstitium. Double-staining studies with an antibody against the macrophage marker CD68 and an anti-COX-2 antibody definitely showed that COX-2 and CD68 often colocalized on the same cell, with only occasional glomerular COX-2-stained mesangial areas. Patients with non-lupus nephropathies had no increase in renal COX-2 expression. These results indicate that COX-2 upregulation is a specific finding of active LN and that monocytes infiltrating the glomeruli contribute to the exaggerated local synthesis of TXA2. If this is correct, COX-2 may soon become a target for therapeutic intervention in this disease.

Identification of a novel gene--SSK1--in human endothelial cells exposed to shear stress

To identify transcriptionally regulated genes potentially involved in the effect of shear stress on endothelial gene expression, we performed a differential display analysis of mRNAs from human umbilical vein endothelial cell (HUVEC) exposed to laminar shear stress (12 dynes/cm2) in comparison to HUVEC maintained in static condition. We identified a cDNA fragment overexpressed by laminar shear stress. The full-length, SSK1, was 3653 long and encoded for a novel protein of 1050 amino acids. Northern blot demonstrates that SSK1 mRNA is expressed at high levels also in placenta, a weak transcript was present in heart, skeletal muscle, kidney and pancreas. Homology searches of the protein databases showed that SSK1 is related to numerous serine-threonine kinases. The highest homology was found with a very recently described gene, BUBR1, an analogue of BUB1, which is a kinase involved in the regulation of cell cycle. The most conserved residues in catalytic domains II, III, VIb, VII, VIII and IX of serine-threonine protein kinases were found in the C terminal region of SSK1 which further supports the kinase nature of the new protein. The putative serine-threonine kinase SSK1 may represent a tool by which mechanical forces regulates phosphorylation events within endothelial cells.

Unselective inhibition of endothelin receptors reduces renal dysfunction in experimental diabetes

Chronic nephropathies are associated with enhanced renal synthesis of endothelin (ET)-1. A recent study demonstrated that an ET(A) receptor antagonist given to diabetic rats at the moment of disease induction prevented the development of renal injury. Here we investigated whether an unselective ET(A)/ET(B) receptor antagonist, PD 142,893, was renoprotective when given to streptozotocin diabetic rats when animals were already proteinuric. The effect of PD 142,893 was compared with that of an ACE inhibitor, lisinopril, known to retard progressive renal disease in experimental and human diabetes. PD 142,893 normalized systemic blood pressure, reduced urinary protein and albumin excretion, and ameliorated renal blood flow in diabetic rats, but it did not affect such parameters in control rats. Lisinopril had a renoprotective effect comparable to PD 142,893, although lisinopril controlled systemic blood pressure better. Northern blot analysis of ET-1 mRNA revealed upregulation of ET-1 gene in the diabetic kidney. Similar results were obtained by in situ hybridization in glomeruli and tubuli of diabetic rats. Both treatments remarkably attenuated exaggerated renal ET-1 gene expression. These data suggest that ET-1 is a contributory mediator of kidney damage in diabetes and indicate that ET receptor antagonists may represent a new therapeutic mean for treatment of progressive diabetic nephropathy.

Pharmacologic control of angiotensin II ameliorates renal disease while reducing renal TGF-beta in experimental mesangioproliferative glomerulonephritis

We evaluated the effect of blocking angiotensin II (AngII) on the development of proteinuria and glomerular injury in antithymocyte serum (ATS) glomerulonephritis. Disease was induced in Sprague-Dawley rats by a single intravenous injection of rabbit ATS. Three groups of rats were considered: group 1 (n = 13), ATS rats with no therapy; group 2 (n = 13), ATS rats treated with angiotensin-converting enzyme inhibitor (40 mg/L lisinopril in the drinking water); and group 3 (n = 13), ATS rats treated with AngII receptor antagonist (50 mg/L L-158,809 in the drinking water). Treatment started 3 hours after ATS injection and lasted 4 days. An additional group of control rats (group 4, n = 13) received preimmune serum. At day 4, ATS rats developed proteinuria (46+/-5 mg/d v control 12+/-1 mg/d; P < 0.01), which was prevented by both lisinopril and L-158,809 (14+/-0.2 mg/d and 15+/-1.6 mg/d, respectively, P < 0.01 v ATS). Systolic blood pressure was comparable in ATS rats and in controls (119+/-4 mm Hg v 120+/-2 mm Hg). Systolic blood pressure values were significantly decreased after either lisinopril or L-158,809 (104+/-3 mm Hg and 101+/-5 mm Hg, respectively; P < 0.01 v ATS). Serum creatinine levels were similar in all groups. Quantitation of proliferating cells and macrophages by analysis of proliferating cell nuclear antigen-positive and ED1-positive cells/glomerular cross-section showed a marked increase in proliferating cell nuclear antigen-positive cells in glomeruli of ATS rats over controls (12.6+/-0.5 cells/glomerular cross-section v 1.9+/-0.2 cells/glomerular cross-section; P < 0.01), which was significantly (P < 0.01) prevented by both treatments (lisinopril, 5.7+/-1.0 cells/glomerular cross-section; L-158,809, 4.8+/-1.5 cells/glomerular cross-section). The increase in ED1-positive cells (10+/-0.7 cells/glomerular cross-section v controls, 1.8+/-0.2 cells/glomerular cross-section; P < 0.01) was also significantly (P < 0.01) reduced by lisinopril and L-158,809 (4.1+/-0.7 cells/glomerular cross-sections and 2.6+/-0.6 cells/glomerular cross-section, respectively). Blocking of AngII activity prevented almost completely the formation of microaneurysms in ATS rats (percent of glomeruli with microaneurysms: ATS, 11.5%+/-3.5%; ATS + lisinopril, 0.4%+/-0.2%; ATS + L-158,809, 0.8%+/-0.8%; controls, 0%). Because AngII is a potent inducer of renal transforming growth factor-beta (TGF-beta), a cytokine involved in the regulation of cell proliferation, matrix deposition, and monocyte migration (which is overexpressed in the kidney of ATS rats), we then evaluated the effect of AngII inhibitors on renal gene expression of TGF-beta1 and on urinary TGF-beta1. TGF-beta1 mRNA levels in kidneys of ATS rats were 3.6-fold higher than those of controls and were reduced by 46% and 32% after treatment with lisinopril and L-158,809, respectively. Urinary TGF-beta1 excretion increased in ATS (37.3+/-6.0 ng/d v controls, 13.8+/-3.4 ng/d; P< 0.01) but was normalized by lisinopril and L-158,809 (7.6+/-1.9 ng/d and 6.4+/-0.4 ng/d, respectively; P < 0.01). Thus, in ATS, blocking AngII synthesis prevents proteinuria and reduces glomerular cell proliferation and inflammatory cell infiltration, possibly by reducing excessive renal TGF-beta synthesis. These findings may be relevant for future strategies in the treatment of human mesangioproliferative glomerulonephritis.

Angiotensin II blockade limits tubular protein overreabsorption and the consequent upregulation of endothelin 1 gene in experimental membranous nephropathy

Proteinuric renal diseases are associated with excessive renal synthesis of endothelin 1 (ET-1) either in experimental animals or humans. This has been interpreted as an upregulation of ET-1 gene in proximal tubular cells secondary to overreabsorption of an unusual amount of filtered proteins. Here we used a model of chronic proteinuria, passive Heymann nephritis (PHN), to localize the structure of the kidney responsible for excessive ET-1 expression and synthesis and to clarify whether drugs that reduce glomerular protein trafficking modified the distribution of ET-1 mRNA and the corresponding peptide in the kidney. PHN was induced in Sprague-Dawley rats after injection of rabbit anti-Fx1A antibody. Group 1 (n = 5) was untreated, group 2 (n = 5) was given daily the angiotensin-converting enzyme inhibitor lisinopril (40 mg/l) plus the angiotensin II receptor antagonist L-158,809 (50 mg/l) from day 7--when rats were already proteinuric--to month 12. An additional group of normal rats (n = 5) was used as controls. Urinary excretion of ET-1 was significantly increased in PHN rats as compared with controls and normalized by the treatment. By in situ hybridization a weak signal for ET-1 mRNA was detectable in glomeruli, distal tubular segments, and proximal tubules of control kidneys. By contrast, a strong labeling was found in the kidneys of rats with PHN which was mainly localized to proximal tubules and renal interstitium. The pattern of renal ET-1-like immunoreactivity was remarkably consistent with ET-1 mRNA expression. In animals with PHN given the angiotensin II blocking therapy, the urinary excretion of proteins normalized, and the structural integrity of the kidney was well preserved. In the kidney tissue taken from these animals, both ET-1 mRNA and protein staining were quite comparable to controls. These data suggest a link between excessive protein tubular reabsorption and enhanced renal ET-1 in chronic nephropathies and provide a novel explanation for the renoprotective effect in vivo of drugs that, by blocking the biological activity of angiotensin II, reduce glomerular protein traffic and possible deleterious effects of excessive tubular protein overloading.