Retention of PDGFR-beta function in mice in the absence of phosphatidylinositol 3'-kinase and phospholipase Cgamma signaling pathways

Signal transduction by the platelet-derived growth-factor receptor beta (PDGFR-beta) tyrosine kinase is required for proper formation of vascular smooth muscle cells (VSMC). However, the importance of individual PDGFR-beta signal transduction pathways in vivo is not known. To investigate the role of two of the pathways believed to be critical for PDGF signal transduction, we have generated mice that bear a PDGFR-beta that can no longer activate PI3kinase or PLCgamma. Although these mutant mice have normal vasculature, we provide multiple lines of evidence in vivo and from cells derived from the mutant mice that suggest that the mutant PDGFR-beta operates at suboptimal levels. Our observations indicate that although loss of these pathways can lead to attenuated PDGF-dependent cellular function, certain PDGFR-beta-induced signal cascades are not essential for survival in mice.

Isolation and characterization of substance P-containing dense core vesicles from rabbit optic nerve and termini

In neurons, neuropeptides and other synaptic components are transported down the axon to the synapse in vesicles using molecular motors of the kinesin family. In the synapse, these neuropeptides are found in dense core vesicles (DCVs), and, following calcium-mediated exocytosis, they interact with receptors on the target cell. We have developed a rapid, large-scale technique for purifying peptide-containing DCVs from specific nuclei in the central nervous system. By using differential velocity gradient and equilibrium gradient centrifugation, neuropeptide-containing DCVs can be separated by size and density from optic nerve (ON) and its termini, the lateral geniculate nuclei and the superior colliculi. Isolated DCVs contain neuropeptides (substance P and brain-derived neurotrophic factor), synaptic vesicle (SV) membrane proteins (SV2, synaptotagmins, synaptophysin, Rab3 and synaptobrevin), SV-associated proteins (alpha-synuclein), secretory markers for DCVs previously isolated (secretogranin II), and beta-amyloid precursor protein. By using electron microscopic techniques, DCV were also visualized and shown to be immunoreactive for neuropeptides, neurotrophins, and SV membrane proteins. Because of the interesting group of physiological and potentially pathophysiological proteins associated with these vesicles; this isolation procedure, applicable to other CNS nuclei, should represent an important research tool.

Vascular endothelial growth factor accelerates renal recovery in experimental thrombotic microangiopathy

BACKGROUND

Renal microvascular injury characterizes thrombotic microangiopathy (TMA). The possibility that angiogenic growth factors may accelerate recovery in TMA has not been studied.

METHODS

TMA was induced in rats by the selective right renal artery perfusion of antiglomerular endothelial cell IgG (30 mg/kg). Twenty-four hours later, rats received vascular endothelial growth factor (VEGF121, 100 microg/kg/day) or vehicle (control) daily until day 14. To evaluate renal function, the unperfused left kidney was removed at day 14, and rats were sacrificed at day 17.

RESULTS

The induction of TMA was associated with loss of glomerular and peritubular capillary endothelial cells and decreased arteriolar density at day 1. Some spontaneous capillary recovery was present by day 17; however, repair was incomplete, and severe tubulointerstitial damage occurred. The lack of complete microvascular recovery was associated with reduced VEGF immunostaining in the outer medulla. VEGF-treated rats had more glomeruli with intact endothelium, less glomerular ischemia (collapsed glomeruli), and greater peritubular capillary density with less peritubular capillary loss. This was associated with less tubulointerstitial fibrosis, less cortical atrophy, and improved renal function.

CONCLUSIONS

VEGF accelerates renal recovery in this experimental model of TMA. These studies suggest that angiogenic growth factors may provide a new therapeutic strategy for diseases associated with endothelial cell injury.

Restricted diet rescues rat enteric motor neurones from age related cell death

BACKGROUND

Alone among autonomic neurones, enteric neurones are known to be vulnerable to age related cell death; over 50% may be lost in aging rodents. A previous study demonstrated unexpectedly that neurones of the myenteric plexus from rats fed a restricted diet appeared not to suffer from extensive cell death in contrast with previous studies of ad libitum fed animals.

AIMS

To compare myenteric neurone numbers in the ileum of young and aging male Sprague-Dawley rats fed either ad libitum or a restricted diet.

METHODS

Neurones were counted in whole mount preparations of rat ileum stained immunohistochemically for the pan-neuronal marker PGP9.5, for choline acetyltransferase, or for nitric oxide synthase, or with NADH or NADPH histochemistry.

RESULTS

Neurone numbers in the rat myenteric plexus were substantially affected by the dietary regimen: ad libitum feeding (50-60 g per day of standard rat chow) resulted in the death of about 50% of myenteric neurones in 24 month Sprague-Dawley rats, while numbers were unchanged when the daily dietary intake was halved between the ages of six and 24 months. Animals fed a double restricted diet (15 g per day) showed no cell loss at 30 months, as well as the predicted increase in longevity. Neurone loss was largely complete by 16 months in ad libitum fed animals. Numbers of cholinergic (possibly motor) neurones, as demonstrated by choline acetyltransferase immunohistochemistry, were substantially reduced in ad libitum fed aging rats but not in animals fed a restricted diet. Loss of cholinergic neurones after ad libitum feeding was confirmed by reduced numbers of neurones of a size range matching that of cholinergic neurones.

CONCLUSIONS

Ad libitum feeding of adult rats has adverse effects on the survival of myenteric neurones, neurone loss commencing before 16 months of age. Cholinergic neurones appear to be particularly vulnerable to the effects of diet. Restricting dietary intake from six months of age prevents neurone loss almost entirely up to 30 months of age in these rats.

Evaluation of toxicokinetic variables and arthropathic changes in juvenile rabbits after oral administration of an investigational fluoroquinolone, PD 117596

OBJECTIVE

To compare toxicokinetic variables and associated tissue drug concentrations with severity of articular lesions in weight-bearing joints of juvenile rabbits after oral administration of a fluoroquinolone.

ANIMAL

Ten 6- to 7-week-old, 800- to 1,200-g, New Zealand White rabbits.

PROCEDURES

Rabbits were gavaged daily with the fluoroquinolone PD 117596 at 500 mg/kg of body weight for 5 days. Blood samples were collected on day 4 at preestablished times, up to 24 hours after drug administration. On day 5 gross lesion severity and prevalence were evaluated in the major weight-bearing joints, and tissue specimens were collected (60 minutes after drug administration). Serum and tissue drug concentrations were determined by microbiologic plate assay.

RESULTS

Macroscopically, treatment rabbits had a high prevalence of arthropathy with the distal portion of the femur having the highest prevalence and severity of lesions. Grossly, alterations to articular cartilage included 1 to 4 mm in diameter vesicles or erosions. Histologically, vesicles were identified in the midzone or close to the zone of calcified cartilage of treatment rabbits. Chondrocyte cellularity was reduced in affected areas, and perivesicular regions had reduced staining with Safranin O. Correlation analysis of area under the curve values with total scores for lesion severity had a significant positive relationship.

CONCLUSIONS

Our findings support the use of juvenile rabbits as a model for arthropathic changes induced by fluoroquinolone administration.

Magnetic resonance imaging in the management of suspected spinal canal disease in patients with known malignancy

AIM

The aim of this study was to examine the spectrum of spinal canal disease in patients with known malignancy using magnetic resonance imaging (MRI).

MATERIALS AND METHODS

One hundred and fifty-five patients underwent a total of 159 spinal MRI examinations over a three-year period. Patients were examined using a 1.0T magnet and a phased array surface spine coil. Sagittal T1 weighted spin echo and STIR sequences were routinely employed. Axial T1 and T2 weighted spin echo images were obtained at sites of identified pathology. Contrast enhanced sagittal and axial T1 weighted spin echo images were acquired when the unenhanced appearances did not correlate with the clinical findings or when the images suggested intradural or intramedullary disease.

RESULTS

Malignant disease affecting the spinal cord or cauda equina was noted in 104/159 (65%) patients (extradural n= 78, intradural n= 20, intramedullary n= 7); one patient had evidence of both intradural and intramedullary deposits. Multiple levels of extradural cord/cauda equina compression were present in 18/78 patients (23%). The thoracic spine was the most frequently affected (74%). Bone elements were the major component of extradural compression in 11/78 patients (14%). Intradural metastases were multiple in 15/20 patients (75%). Four of the six solitary intramedullary metastases were situated in the conus medullaris.

CONCLUSION

Magnetic resonance imaging of the entire spine is the investigation of choice in patients with known malignancy and suspected spinal canal disease. Contrast-enhanced images should be acquired when the unenhanced appearances do not correlate with the clinical findings or when they suggest intradural or intramedullary disease.Loughrey, G. J. (2000). Clinical Radiology55, 849-855.

Osteopontin expression in progressive renal injury in remnant kidney: role of angiotensin II

BACKGROUND

Osteopontin (OPN) is a macrophage chemotactic and adhesion molecule and has been shown to play a role in glomerular and tubulointerstitial injury in several kidney disease models.

METHODS

The present study examined whether OPN expression is involved in the progression of renal disease following subtotal (5/6) nephrectomy (STNx) in rats and whether angiotensin II (Ang II) mediates the up-regulation of renal OPN expression and macrophage accumulation in this model by administering valsartan, an Ang II type I (AT1) receptor antagonist, or ramipril, an angiotensin-converting enzyme (ACE) inhibitor.

RESULTS

In normal and sham-operated rat kidneys, OPN was expressed in a few tubules (<5%) and was absent in glomeruli. Following STNx (weeks 2 to 16), there was substantial up-regulation of OPN mRNA and protein expression in glomeruli [2 to 12 cells/glomerular cross section (gcs)] and tubular epithelial cells (20 to 75% OPN+). The up-regulation of OPN expression was associated with macrophage accumulation within the kidney, severe proteinuria, loss of renal function, and severe histologic damage, including tubulitis and tubulointerstitial fibrosis (all P < 0.001). Treatment with either valsartan or ramipril completely abrogated the up-regulation of OPN mRNA and protein expression in glomeruli and tubules. The reduction in OPN expression was associated with a significant inhibition of macrophage accumulation and progressive renal injury (P < 0.001).

CONCLUSION

An up-regulation of OPN expression may play a role in progressive renal injury following STNx. Inhibition of OPN expression may be one of the mechanisms by which Ang II blockade attenuated renal injury after renal ablation.

Involvement of macrophage migration inhibitory factor (MIF) in experimental uric acid nephropathy

BACKGROUND

Deposition of uric acid in the kidney can lead to progressive tubulointerstitial injury with granuloma formation. We hypothesized that uric acid crystal deposition may induce granuloma formation by stimulating local expression of macrophage migration inhibitory factor (MIF), which is a known mediator of delayed type hypersensitivity (DTH).

MATERIALS AND METHODS

A model of acute uric acid nephropathy was induced in rats by the administration of oxonic acid (an inhibitor of uricase), together with uric acid supplements. MIF expression and local cellular response were examined by in situ hybridization and immunohistochemistry.

RESULTS

Kidney tissue examined at 35 days posttreatment showed widespread tubulointerstitial damage with intratubular uric acid crystal deposition and granuloma formation. Tubules within the areas of granuloma showed a six-fold increase in MIF mRNA, compared with uninvolved areas by in situ hybridization. Moreover, the areas of increased MIF mRNA expression correlated with sites of dense accumulation of macrophages and T cells, and these cells were activated when assessed by the expression of interleukin-2R (IL-2R) and (MHC) class II. Interestingly, cytoplasmic staining for MIF protein in the uric acid (UA) crystal-associated granulomatous lesions was reduced, indicating a rapid MIF secretion by damaged tubules and macrophages secondary to uric acid crystal stimulation. This was confirmed by the demonstration of a marked increase in urinary MIF protein by Western blot analysis. Control rats fed either a normal diet or only oxonic acid had no discernible evidence of renal disease by routine light microscopy and minimal tubular expression of MIF mRNA and protein.

CONCLUSIONS

These data suggest that intrarenal granulomas in urate nephropathy may be the consequence of a crystal induced DTH reaction mediated by MIF.

Tubulointerstitial injury and loss of nitric oxide synthases parallel the development of hypertension in the Dahl-SS rat

OBJECTIVE

Alterations in renal nitric oxide (NO) are involved in the hypertension of the Dahl salt-sensitive (Dahl-SS) rat We sought to identify the kinetics and sites of expression of the major NO synthase (NOS) isoforms.

DESIGN

The renal expression of the major NOS were examined in Dahl-SS and salt-resistant rats (Dahl-SR) while on a low salt (0.1% NaCl) diet at 3 and 9 weeks of age.

METHODS

Renal biopsies from Dahl-SS and Dahl-SR rats were compared for evidence of renal injury and for alterations in expression of the NOS enzymes by quantitative immunohistochemistry.

RESULTS

At 3 weeks of age Dahl-SS and Dahl-SR rats have normal renal histology and similar immunohistochemical expression of NOS1, -2, and -3. At 9 weeks Dahl-SS rats had significantly higher blood pressure than Dahl-SR rats (P< 0.005 ), and lower macula densa NOS1 (P< 0.05) and cortical and medullary NOS3 (P< 0.05). NOS2 was reduced in cortical tubules in biopsies showing severe tubulointerstitial damage, but was not significantly different between Dahl-SS and Dahl-SR groups as a whole. Dahl-SS rats also manifested glomerular and tubulointerstitial injury. Tubular expression of osteopontin (OPN), which is an inhibitor of NOS2, correlated with the systolic BP in individual Dahl-SS rats (r2 = 0.80, P < 0.0001 ).

CONCLUSION

Tubulointerstitial injury and the loss of NOS occur after birth and parallel the development of hypertension. We suggest that the structural and functional changes that occur with renal injury in the Dahl-SS rat may contribute to the development of hypertension.

Toxicity of various amyloid beta peptide species in cultured human blood-brain barrier endothelial cells: increased toxicity of dutch-type mutant

The amyloid beta peptide (A beta) is the major component of the neuritic and cerebrovascular amyloid plaques that are one of the characteristic features of Alzheimer's disease (AD). This peptide has been shown to be toxic to several relevant cell types, including neurons, cerebrovascular smooth muscle cells, and endothelial cells. We have studied the toxic effects of both soluble and aggregated species of A beta(1-40) and the mutation A beta(1-40)Glu-->Gln(22), which is the major species deposited in the cerebrovascular blood vessels of victims of hereditary cerebral hemorrhage with amyloidosis, Dutch type. We find that aggregates of both peptides, as well as of A beta(1-42) and A beta(25-35), are toxic to cultured human cerebrovascular endothelial cells (hBEC) obtained from the brain of a victim of AD (at doses lower than those that are toxic to CNS neurons or leptomeningeal smooth muscle cells). Soluble A beta(1-40) Gln(22) is equally toxic to hBEC, whereas wild-type A beta(1-40) is toxic only at higher doses. This toxicity is seen at the lowest dose of A beta(1-40) Gln (22) used, 20 nM. The soluble A beta(1-40)Gln(22) aggregates on the surface of the cells, in contrast to A beta(1-40), and its toxicity can be blocked both by an inhibitor of free radical formation and by Congo red, which inhibits amyloid fibril formation. We discuss the possibility that the enhanced toxicity of A beta(1-40)Gln(22) is mediated by a A beta receptor on the endothelial cells.

Serum amyloid A in Alzheimer's disease brain is predominantly localized to myelin sheaths and axonal membrane

Immunohistochemical localization of the injury specific apolipoprotein, acute phase serum amyloid A (A-apoSAA), was compared in brains of patients with neuropathologically confirmed Alzheimer's disease (AD), multiple sclerosis (MS), Parkinson's disease (PD); Pick's disease (Pick's), dementia with Lewy bodies (DLB), coronary artery disease (CAD), and schizophrenia. Affected regions of both AD and MS brains showed intense staining for A-apoSAA in comparison to an unaffected region and non-AD/MS brains. The major site of A-apoSAA staining in both diseases was the myelin sheaths of axons in layers V and VI of affected cortex. A-apoSAA contains a cholesterol binding site near its amino terminus and is likely to have a high affinity for cholesterol-rich myelin. These findings, along with our recent evidence that A-apoSAA can inhibit lipid synthesis in vascular smooth muscle cells suggest that A-apoSAA plays a role in the neuronal loss and white matter damage occurring in AD and MS.

Treatment of hepatitis C-associated glomerular disease

Hepatitis C virus (HCV) infection can lead to chronic active hepatitis, cirrhosis, and liver failure; however it is also associated with a wide range of extrahepatic features. Renal manifestations include cryoglobulinemic membranoproliferative glomerulonephritis and membranous nephropathy. Treatment of HCV with alpha-interferon is only moderately effective and suffers from a high relapse rate. More recently, combination therapy with ribavirin has led to improved suppression of HCV RNA levels. In this review we briefly describe the features of renal disease associated with HCV infection and discuss the therapeutic options.

Distinct patterns of glomerular disease in Lima, Peru

AIM

We performed both a retrospective and prospective study to elucidate the types of glomerular diseases present in adults in Lima, Peru.

MATERIAL AND METHODS

In the retrospective study, we analyzed 1,263 renal biopsies over a 10-year period (1985 -1995) that were processed at a central reference renal pathology laboratory in Lima. 101 cases were examined in the prospective study.

RESULTS

The most common glomerular diseases observed were those due to systemic lupus erythematosus (30.2%), membranoproliferative glomerulonephritis (MPGN, 14.8%), and focal and segmental glomerulosclerosis (FSGS, 13.9%). Although mesangial-proliferative nephritis was observed in 9.5% of cases, IgA nephropathy was rare (0.9%). Examination of the year to year frequency showed that MPGN has tended to decrease in frequency with time whereas FSGS has been increasing. Although there is known to be a high frequency of infections in Peru, only 4.2% of the cases in the retrospective study were associated with infection. Furthermore, in the prospective study, only one case of hepatitis C and no cases of hepatitis B viral infection were detected, including in the 11 cases of MPGN observed.

CONCLUSION

We conclude that the epidemiology of glomerular disease in Lima, Peru, is distinct from most areas of the world, but has similarities to certain regions in Africa, in that MPGN is common whereas IgA nephropathy appears to be rare. Further studies are necessary to elucidate the reasons why the patterns of glomerular disease are different from that observed in other parts of the world.

Noncontact anterior cruciate ligament injuries: risk factors and prevention strategies

An estimated 80,000 anterior cruciate ligament (ACL) tears occur annually in the United States. The highest incidence is in individuals 15 to 25 years old who participate in pivoting sports. With an estimated cost for these injuries of almost a billion dollars per year, the ability to identify risk factors and develop prevention strategies has widespread health and fiscal importance. Seventy percent of ACL injuries occur in noncontact situations. The risk factors for non-contact ACL injuries fall into four distinct categories: environmental, anatomic, hormonal, and biomechanical. Early data on existing neuromuscular training programs suggest that enhancing body control may decrease ACL injuries in women. Further investigation is needed prior to instituting prevention programs related to the other risk factors.

C5b-9 membrane attack complex mediates endothelial cell apoptosis in experimental glomerulonephritis

We studied the role of the C5b-9 membrane attack complex in two models of inflammatory glomerulonephritis (GN) initiated by acute glomerular endothelial injury in Piebold-viral-Glaxo (PVG) complement-sufficient rats (C+), C6-deficient rats (C6-), and rats systematically depleted of complement with cobra venom factor (CVF). GN was induced by performing a left nephrectomy and selectively perfusing the right kidney with either 1) the lectin concanavalin A (Con A) followed by complement-fixing anti-Con A (Con A GN) or 2) purified complement-fixing goat anti-rat glomerular endothelial cell (GEN) antibody [immune-mediated thrombotic microangiopathy (ITM)]. Comparable levels of GEN apoptosis were detected in C+ animals in both models. CVF administration reduced GEN apoptosis by 10- to 12-fold. GEN apoptosis was C5b-9 dependent because PVG C6- rats were protected from GEN loss. Furthermore, functional inhibition of the cell surface complement regulatory protein CD59 by renal perfusion with anti-CD59 antibody in ITM resulted in a 3.5-fold increase in GEN apoptosis. Last, in Con A GN, abrogation of GEN apoptosis preserved endothelial integrity and renal function. This study demonstrates the specific role of C5b-9 in the induction of GEN apoptosis in experimental inflammatory GN, a finding with implications for diseases associated with the presence of antiendothelial cell antibodies.

Mechanisms of increased venous smooth muscle tone in desoxycorticosterone acetate-salt hypertension

The purpose of the present study was to identify mechanisms that contribute to increased venous smooth muscle tone in desoxycorticosterone acetate (DOCA)-salt hypertension in rats. Male Sprague-Dawley rats were uninephrectomized, received subcutaneous implants of DOCA, and drank 1% sodium chloride/0.2% potassium chloride solutions. Sham-operated rats received only uninephrectomy and drank tap water. Three to 4 weeks later, arterial and venous catheters were implanted for measurements of arterial and central venous pressures, respectively, and a silicone balloon catheter was permanently fixed in the right atrium to produce brief circulatory arrest. Venous smooth muscle activity was estimated on the basis of repeated measurements of mean circulatory filling pressure in conscious rats resting in their home cages. DOCA-salt-treated rats were hypertensive and had elevated mean circulatory filling pressure compared with normotensive sham-operated rats. Blockade of the endothelin subtype A receptor with 1 mg/kg ABT-627 IV decreased arterial blood pressure and mean circulatory filling pressure significantly more in hypertensive rats than in normotensive rats. Ganglionic blockade with 30 mg/kg hexamethonium IV also decreased arterial blood pressure and mean circulatory filling pressure more in hypertensive than in normotensive rats. Pretreatment with ABT-627 did not affect subsequent hemodynamic responses to ganglionic blockade. We conclude that venous smooth muscle tone is increased in DOCA-salt hypertension through the independent actions of both endogenous endothelin-1 acting on subtype A receptors and sympathetically mediated venoconstrictor activity.

Osteopontin expression in human crescentic glomerulonephritis

Osteopontin expression in human crescentic glomerulonephritis.

BACKGROUND

Osteopontin is a molecule with diverse biological functions, including cell adhesion, migration, and signaling. The expression of osteopontin has been demonstrated in a number of models of renal injury in association with accumulations of monocyte/macrophages, including recent reports of osteopontin expression in glomerular crescents in a rat model of anti-glomerular basement membrane glomerulonephritis.

METHODS

Glomerular expression of osteopontin in biopsies of human crescentic glomerulonephritis (N = 25), IgA nephropathy with crescents (N = 2), and diffuse proliferative lupus glomerulonephropathy with crescents (N = 1) was studied by immunohistochemistry, in situ hybridization, and combined immunohistochemistry/in situ hybridization. Additionally, antibodies to cell-specific phenotypic markers were used to identify cellular components of the glomerular crescent, which express osteopontin protein and mRNA.

RESULTS

All of the crescents present in the biopsies studied contained a significant number of cells that expressed osteopontin protein and mRNA, demonstrated by immunohistochemistry and in situ hybridization, respectively. Using replicate tissue sections and combined immunohistochemistry/in situ hybridization, we showed that the majority of the strongly osteopontin-positive cells are monocyte/macrophages. In addition to the very strong and cell-associated localization, a weaker and more diffuse pattern of osteopontin protein and mRNA expression could be seen in a number of crescents. None of the osteopontin mRNA-expressing cells could be identified as parietal epithelial cells, CD3-positive T cells, or alpha-smooth muscle actin-positive myofibroblasts. Interstitial monocyte/macrophages did not express osteopontin, except when located in a periglomerular inflammatory infiltrate.

CONCLUSIONS

Macrophages present in the human glomerular crescent express osteopontin protein and mRNA at a high level. This expression supports a role for osteopontin in the formation and progression of the crescentic lesion via chemotactic and signaling properties of the molecule.

Calreticulin is transported to the surface of NG108-15 cells where it forms surface patches and is partially degraded in an acidic compartment

Although calreticulin (Crt) is primarily localized to the endoplasmic reticulum (ER), our results using biotinylation and immunocytochemical methods indicate that a small but significant amount of Crt is present and forms large patches on the surface of NG108-15 cells (a mouse neuroblastoma-rat glioma hybrid cell line). (35)S-labelled Crt molecules begin to reach the cell surface after only 10 min of labelling and disappear slowly from the cell surface. After 4 hr of labelling, approximately half of the newly synthesized Crt molecules are on the cell surface. We believe that some Crt molecules may escape from the KDEL receptor-mediated salvage pathway as they are synthesized and proceed through the secretory pathway to the cell surface. Immunoprecipitation from the culture medium shows that Crt is not released from the cell surface to the medium, suggesting tight binding to surface molecules. NH(4)Cl can block the degradation of Crt; therefore, Crt is presumably degraded in the lysosome pathway. However, blockage of the disappearance of surface Crt is less efficient than that of internal Crt. This suggests that the disappearance of Crt from the cell surface may not be due solely to its degradation, but may reflect transport into another cell compartment such as the ER.

Clinicopathologic correlations in lupus nephritis in Lima, Peru

BACKGROUND

We assessed whether immunohistologic markers for glomerular or tubulointerstitial injury might provide better correlations with ongoing renal function and disease activity as compared with the WHO classification or the NIH activity and chronicity indices in lupus nephritis.

METHODS

Thirty-three patients with clinically defined systemic lupus underwent renal biopsy over a 1-year period at Hospital Loayza in Lima, Peru. Biopsy specimens were evaluated for macrophages, proliferating cells, alpha-actin expression, and type IV collagen deposition in both glomeruli and the tubulointerstitium and the results compared with the current WHO and NIH classifications in relation to the clinical presentation.

RESULTS

Patients with WHO class IV lupus nephritis were more likely to have lower serum complements, greater proteinuria and hematuria, and worse renal function. An elevated NIH activity index correlated with microhematuria, proteinuria, and impaired renal function, whereas an elevated chronicity index correlated with renal function, hypertension, and microhematuria, but not with proteinuria. The presence of glomerular macrophages correlated with both glomerular alpha-actin expression and type IV collagen deposition, but did not correlate with renal function or proteinuria. In contrast, interstitial macrophages correlated not only with interstitial collagen deposition and myofibroblast accumulation, but also correlated with both renal function and the presence of nephrotic syndrome.

CONCLUSIONS

Both the WHO classification and the NIH activity/chronicity indices correlate with clinical manifestations of lupus nephritis. While glomerular macrophage accumulation correlates with mesangial cell activation (alpha-actin expression) and collagen deposition, and interstitial macrophage accumulation correlates with interstitial fibroblast activation and collagen deposition, only interstitial macrophages correlate with renal function. Of particular interest will be future studies to determine whether these markers correlate with the prognosis.

Analysis of factors that affect outcome of primary cadaveric renal transplantation in the UK. HLA Task Force of the Kidney Advisory Group of the United Kingdom Transplant Support Service Authority (UKTSSA)

BACKGROUND

In the UK, kidneys are exchanged between centres on the basis of matching for HLA. We analysed various factors that might affect graft outcome to establish whether exchange of kidneys on this basis remains valid.

METHODS

6363 primary cadaveric renal transplants carried out in 23 centres in the UK between 1986 and 1993 were used in the analysis. 6338 (99.6%) patients who underwent transplantation were followed up at 1 year. 5-year follow-up data were available for 2907 (97.8%) of the 2972 patients who survived to 5 years. We made random checks to validate the data. A multifactorial analysis with Cox's proportional hazards models was used to analyse factors that had a possible effect on graft outcome. To ensure that the analysis of matching was constant during the 8-year study, our analysis was based on the HLA antigens used for organ exchange (11 A locus antigens, 27 B locus antigens, and 12 DR locus antigens). We assessed overall outcome at 5 years and during three periods after transplantation at: 0-3 months, 3-36 months, and after 36 months.

FINDINGS

The following factors were significantly associated with graft outcome in the multifactorial analysis: year of graft, age of donor, age of recipient, whether the recipient had diabetes, cause of donor's death, cold ischaemic time, transport of kidneys, transplant centre, and matching for HLA. The best outcome was achieved with kidneys that had no mismatches at HLA-A, HLA-B, and HLA-DR loci (000 mismatches). The next most favourable outcome was achieved with one mismatch at either A or B loci or one mismatch at both the A and B , but no mismatch at the DR locus (100, 010, or 110 mismatches). Age of the donor and recipient had a significant effect on transplant outcome: older age was associated with increased risk of graft failure.

INTERPRETATION

Various factors affect the outcome of primary cadaveric renal transplantation, particularly the age of the donor and the recipient. However, the effect of matching for HLA remains a strong one and fully justifies the continuing policy in the UK of exchanging kidneys on the basis of HLA matching, especially to recipients when there is a 000 mismatch for HLA between donor and recipient. On the basis of this analysis, a new allocation scheme for kidneys was introduced in the UK in 1998. During the first 9 months of the scheme, there has been a doubling of the number of HLA-000 mismatched kidneys transplanted.

KDEL proteins are found on the surface of NG108-15 cells

Although KDEL proteins are primarily localized to the endoplasmic reticulum (ER), we have employed surface biotinylation method to demonstrate that the KDEL proteins calreticulin (Crt), protein disulfide isomerase (PDI) and the 78-kDa glucose regulated protein (GRP78) are found on the surface of the NG108-15 cell line. In contrast, the 94-kDa glucose regulated protein (GRP94), another KDEL protein, is not found on the cell surface. Calnexin (Cnx), a type-1 integral transmembrane ER protein which is partially homologous to Crt but lacks the KDEL sequence, is not detected on the cell surface either. While only small amounts of the total GRP78, PDI and Crt molecules exist on the cell surface at steady state, a significant fraction of the newly synthesized molecules are transported to the cell surface and transport of these proteins is inhibited by treatment with brefeldin A. The surface GRP78 contains the KDEL sequence. On the cell surface, GRP78, PDI and Crt associate with other proteins and form complexes of different sizes. Surface Crt is found to be essential for the neurite formation when NG108-15 cells are induced to differentiate using dibutyryl cAMP.

A new national allocation scheme for adult kidneys in the United Kingdom. United Kingdom Transplant Support Service Authority (UKTSSA) Users' Kidney Advisory Group and its Task Forces

A new allocation scheme for kidneys from adult cadaver donors was introduced in the UK on July 1st, 1998. The new scheme is based on data from an analysis of factors influencing transplant survival instigated by the Kidney Advisory Group (KAG) of the UKTSSA. A cohort of 6,363 first cadaver allografts performed in the UK between 1986-1993 was used for the analysis with 99.6% one-year follow-up and 97.8% 5-year follow-up. HLA matching was one of a number of factors that were found to influence transplant survival, thus supporting the policy of exchange of kidneys based on matching. The new allocation scheme is based on 3 tiers in which cadaver organs are offered first in Tier 1 to patients with zero HLA antigen mismatches (000 matchgrade), in Tier 2 to favorably matched patients, (matched for HLA-DR and mismatched for a maximum of one HLA-A and one-B locus antigen -100, 010, 110 matchgrades) and remaining kidneys in Tier 3 to non-favorably matched patients. A points score devised by a subgroup of the KAG to reflect natural justice and common sense is used as a discriminator between equally matched patients. The points are based on recipient age, donor-recipient age difference, waiting time, matchability for HLA antigens, sensitization to HLA antigens and the transplant unit balance of organ exchange. The performance of the scheme will be closely monitored, but computer simulations predict that there will be an overall improvement in transplant survival as a result of an increase in well matched transplants.

Dissociation of mesangial cell migration and proliferation in experimental glomerulonephritis

BACKGROUND

Recently, we documented that following in vivo mesangial cell (MC) ablation in the Thy1 model, reconstitution of the mesangium occurs by a coordinated proliferation and migration of Thy1 (OX-7)-positive cells originating from the hilus and extraglomerular mesangium. We investigated the role of basic fibroblast growth factor (bFGF) in the mediation of these events.

METHODS

Rats were injected with antithymocyte serum and 48 hours later were pulsed with 3H-thymidine to label proliferating cells. Ninety minutes later, a baseline renal biopsy was obtained, and rats were injected with neutralizing anti-bFGF antibodies or control IgG. Sacrificial biopsies were obtained at 96 hours of disease. Using computer image analysis, biopsies from both time points were quantitated for the number of radiolabeled MC (proliferation) and their mean distance from the hilus (migration). The effect of bFGF on the migration of MCs in culture was examined using a chemotactic assay.

RESULTS

At sacrifice, autoradiographs of rats receiving anti-bFGF had significantly fewer radiolabeled MCs as compared with rats receiving control IgG (8.7+/-1.9 vs. 14.7+/-3.5, P = 0.0001), yielding an overall 40% reduction in proliferation. There was no difference, however, in the final distance of radiolabeled MCs from the glomerular hilus in the two groups, indicating that the administration of anti-bFGF did not effect MC migration in this model. In an in vitro chemotactic assay, MCs migrated in response to platelet-derived growth factor (PDGF) BB (20 ng/ml), but did not migrate in response to bFGF at a wide range of concentrations (0.5 to 50 ng/ml).

CONCLUSIONS

These studies demonstrate that bFGF is an important mediator of MC proliferation but that it does not significantly influence MC migration. This is the first demonstration showing that the mediators effecting proliferation can be dissociated from those mediating migration in renal injury.