Mast cells find their way to the kidney.
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Animals↗
Biomedical subjects
A A Eddy
Publications and source records attributed to A A Eddy.
PAI-1 deficiency attenuates the fibrogenic response to ureteral obstruction.
BACKGROUND: Progressive renal disease is characterized by the induction of plasminogen activator inhibitor-1 (PAI-1), suggesting that impaired activity of the renal plasmin cascade may play a role in renal fibrosis. METHODS: To test this hypothesis, the severity of renal fibrosis caused by unilateral ureteral obstruction (UUO) was compared in PAI-1 wild-type (+/+) and PAI-1 deficient (-/-) mice. The extent of interstitial inflammation and fibrosis, renal plasminogen activator and plasmin activity, and renal expression of profibrotic genes was evaluated after 3, 7, and 14 days of UUO. RESULTS: Renal PAI-1 mRNA levels increased 8- to 16-fold in the +/+ mice after UUO surgery, and PAI-1 protein was detected in kidney homogenates. Interstitial fibrosis was significantly attenuated in -/- mice compared with +/+ mice at day 7 and day 14, based on the interstitial area stained with picrosirius red and total kidney collagen content. However, neither the mean renal plasminogen activator nor plasmin activities were increased in -/- mice compared with +/+ mice. The number of interstitial macrophages were significantly lower in the -/- mice three and seven days after UUO; interstitial myofibroblasts were significantly fewer at three days. At the same time points, this altered interstitial cellularity was associated with a significant reduction in renal mRNA levels for transforming growth factor-beta and procollagens alpha 1(I) and alpha 1(III). CONCLUSIONS: These studies establish an important fibrogenic role for PAI-1 in the renal fibrogenic response. The results demonstrate that one important fibrosis-promoting function of PAI-1 is its role in the recruitment of fibrosis-inducing cells, including myofibroblasts and macrophages.
Animals↗
Molecular basis of renal fibrosis.
All progressive renal diseases are the consequence of a process of destructive fibrosis. This review will focus on tubulointerstitial fibrosis, the pathophysiology of which will be divided into four arbitrary phases. First is the cellular activation and injury phase. The tubules are activated, the peritubular capillary endothelium facilitates migration of mononuclear cells into the interstitium where they mature into macrophages, and myofibroblasts/activated fibroblasts begin to populate the interstitium. Each of these cells releases soluble products that contribute to ongoing inflammation and ultimately fibrosis. The second phase, the fibrogenic signaling phase, is characterized by the release of soluble factors that have fibrosis-promoting effects. Several growth factors and cytokines have been implicated, with primary roles suggested for transforming growth factor-beta, connective tissue growth factor, angiotensin II and endothelin-1. Additional factors may participate including platelet-derived growth factor, basic fibroblast growth factor, tumor necrosis factor-alpha and interleukin-1, while interferon-gamma and hepatocyte growth factor may elicit antifibrotic responses. Third is the fibrogenic phase when matrix proteins, both normal and novel to the renal interstitium, begin to accumulate. During this time both increased matrix protein synthesis and impaired matrix turnover are evident. The latter is due to the renal production of protease inhibitors such as the tissue inhibitors of metalloproteinases and plasminogen activator inhibitors which inactivate the renal proteases that normally regulate matrix turnover. Fourth is the phase of renal destruction, the ultimate sequel to excessive matrix accumulation. During this time the tubules and peritubular capillaries are obliterated. The number of intact nephrons progressively declines resulting in a continuous reduction in glomerular filtration.
Animals↗
Interstitial fibrosis in mice with overload proteinuria: deficiency of TIMP-1 is not protective.
BACKGROUND: Progressive renal interstitial fibrosis is characterized by up-regulated expression of the gene that encodes the tissue inhibitor of metalloproteinases-1 (TIMP-1), a regulator of extracellular matrix remodeling, suggesting that impaired matrix turnover contributes to the fibrogenic process. The present study was designed to develop a murine model of renal interstitial fibrosis, and to determine the functional significance of up-regulated Timp-1 expression by comparing the severity of this renal disease in wild-type mice and mice genetically deficient in Timp-1. METHODS: Initial pilot studies developed and characterized a murine model of bovine serum albumin (BSA)-induced protein-overload proteinuria with respect to the degree of proteinuria, severity of interstitial fibrosis, and renal mRNA levels for genes encoding matrix proteins, transforming growth factor-beta1 (TGF-beta1), and TIMP-1, -2, -3, and -4. In the final study, the severity of interstitial fibrosis was compared in wild-type and Timp-1-deficient mice after six weeks of proteinuria. RESULTS: Mice injected with large daily intraperitoneal doses of BSA developed proteinuria, interstitial inflammation, and progressive interstitial fibrosis. A time course study based on measurements after one, two, and six weeks of BSA injections showed increased renal mRNA levels for the matrix genes procollagens alpha1(I), alpha1(III), and alpha2(IV) and TGF-beta1 and Timp-1. Timp-2 and Timp-3 genes were constitutively expressed at high levels in the normal kidneys and showed little change in the proteinuric kidneys. Timp-4 transcripts were not detected in any of the kidneys. After six weeks of BSA overload-proteinuria, the groups (N = 8 per group) of wild-type and Timp-1-deficient mice developed significant interstitial fibrosis compared with the control saline-injected groups. The severity of the interstitial fibrosis was similar in both proteinuric groups based on an assessment of the final kidney weight, total kidney collagen content, and the number of interstitial fields with increased fibronectin staining. CONCLUSIONS: Results of the present study indicate that TIMP-1 deficiency does not alter the degree of interstitial fibrosis in the murine overload proteinuria model. Potential explanations include Timp-1 genetic redundancy, as suggested by the observation that, despite significant intrarenal induction of the Timp-1 gene expression, net renal metalloproteinase-9 (MMP-9) activity was not significantly altered. TIMP-1 is a multifunctional protein that may play a metalloproteinase-independent role in response to renal injury.
Animals↗
A morbid course in a girl with mixed connective tissue disease.
We describe an 18-year-old girl with a 13-year history of mixed connective tissue disease whose clinical course was unique: she ultimately developed end-stage kidney and bowel disease that led to a protracted morbid clinical course. We report this case to alert pediatric nephrologists to the importance of early recognition of possible intestinal disease in these patients. Unfortunately, no therapy is currently known to reverse the pathological process in the bowel, but multiorgan transplantation might be an option if the numerous medical complications of end-stage bowel disease can be successfully controlled.
Adolescent↗
Proton stoichiometry of the overexpressed uracil symport of the yeast Saccharomyces cerevisiae.
Information about the molecular biology of the uracil carrier of Saccharomyces cerevisiae is now available but its properties as a symport are unexplored. We have now studied its proton stoichiometry at pH 6.5, 4.8 and 4.2, in a yeast strain overexpressing the symport and unable to metabolize uracil. After the depletion of cellular ATP, uracil uptake followed an approximately exponential time course to reach a plateau. Proton uptake was then indistinguishable from the basal rate shown in controls without added uracil. It was concluded that more than 87% of the uracil flux through the system was coupled to symported protons. Because the basal rate was a significant fraction of the total rate of proton uptake at pH 4.2 or 4.8, the ratio of the proton and uracil flows could not be defined uniquely during the initial near-linear phase of uptake. However, the average rate of proton uptake during increasing time intervals up to 120 s was shown to be a linear function of the corresponding average rate of uracil uptake. This relationship, defining approx. 90% of the eventual uracil uptake, was used to deduce the mean proton stoichiometry as approx. 3 at pH 4.2, falling to near 2 at pH 6.5. The rate of uracil uptake increased 4-fold when the negative proton gradient (Delta mu(H)) acting across the plasma membrane increased from 60 to 200 mV. The rate fell markedly after depolarization by KCl. The maximum uracil gradient (Delta mu(S)) was less affected by depolarization. The ratio Delta mu(S)/Delta mu(H) fell from approx. 2 to near 1 as Delta mu(H) increased in the above range. In contrast with the starved yeast, uracil accumulation during energy metabolism followed a pump-leak model.
Biological Transport↗
Interstitial fibrosis in hypercholesterolemic rats: role of oxidation, matrix synthesis, and proteolytic cascades.
Uninephrectomized rats with diet-induced hypercholesterolemia develop interstitial inflammation and fibrosis after 8 to 12 weeks. Fibrosis has been associated with the accumulation of lipid peroxidation products within the tubulointerstitium, along with increased renal mRNA levels for transforming growth factor beta-1 (TCF-beta 1), some matrix proteins, and the tissue inhibitor of metalloproteinases (TIMP-1). However, mRNA levels for urokinase-type plasminogen activator (uPA) have been found to be decreased. The purpose of the present study was to determine whether antioxidant therapy could attenuate interstitial fibrosis in hypercholesterolemic rats and to determine changes in the pattern of renal gene expression induced by antioxidant therapy. Three groups of uninephrectomized rats were studied after 12 weeks of feeding standard rat chow, an atherogenic diet (standard chow plus 4% cholesterol/1% cholic acid), or an atherogenic diet supplemented with high doses of the antioxidants probucol and vitamin E. Rats fed the atherogenic diet developed hypercholesterolemia and a 56% increase in total kidney collagen compared with rats fed standard chow. In comparison, the hypercholesterolemic rats treated with antioxidants had normal levels of renal lipid peroxidation products and a normal kidney collagen content. In contrast, there were no significant differences in urinary albumin excretion rates or the number of interstitial macrophages between the two hypercholesterolemic groups. Compared with the untreated hypercholesterolemic group, antioxidant therapy induced significant reductions in renal mRNA levels for procollagen III (to 60% of untreated levels), collagen IV (60%), and TIMP-1 (20%), while uPA levels were significantly increased (to 210%). Paradoxically, antioxidant therapy was associated with a significant increase in renal TGF-beta 1 mRNA levels (to 150%), although TGF-beta 1 protein expression shifted from interstitial to tubular epithelial cells in predominance. The results of the present study demonstrate the efficiency of antioxidant therapy in preventing renal interstitial fibrosis in hypercholesterolemic rats with a single kidney. Based on changes in renal gene expression at the mRNA level, impaired matrix protein synthesis and increased intrarenal activity of the metalloproteinases and uPA/plasmin may play a role in the attenuation of fibrosis.
Animals↗
Failure of antioxidant therapy to attenuate interstitial disease in rats with reversible nephrotic syndrome.
The present two studies were designed to determine whether oxidized LDL contributes to the tubulointerstitial changes seen in rats during the acute phase of acute puromycin aminonucleoside nephrosis (PAN). In the single-dose study, rats were given one injection of puromycin aminonucleoside (PA; 15 mg/100 g body wt) and killed 1, 2, or 3 wk thereafter. The four animal groups were saline controls, PAN controls, PAN plus probucol, and PAN plus lovastatin. This study showed that the addition of probucol significantly reduced the mean levels of serum cholesterol and renal lipid-peroxidation products, an effect not seen with lovastatin therapy. Compared with saline controls, PAN controls had a significant increase in total kidney collagen (7.9 +/- 1.2 versus 5.9 +/- 0.6 mg/kidney at 3 wk). Neither probucol nor lovastatin therapy attenuated the interstitial inflammation or fibrosis. In the multidose study, rats were given the same initial PA dose and were uninephrectomized on day 12. They were killed on day 35 after two smaller PA doses were given on days 16 and 23. Animal groups were saline controls, PAN controls, PAN plus probucol, and PAN plus vitamin E. Hepatic lipid-peroxidation products were significantly lower in the probucol-treated, but not in the vitamin E-treated, PAN groups when compared with the PAN controls. Neither probucol nor vitamin E prevented the increase in total kidney collagen that was observed in the PAN control group (7.4 +/- 0.7, 10.1 +/- 2.6, and 9.3 +/- 1.8 mg of collagen/kidney, respectively, versus 5.4 +/- 0.5 mg/kidney for the saline controls). Renal cortical mRNA levels for matrix-encoding genes and protease inhibitors were similar in the three nephrotic groups. Transforming growth factor-beta1 mRNA levels were highly variable within each group and not significantly different at day 35, but showed a significant positive correlation with the degree of albuminuria (r = 0.70). The present results demonstrate that the treatment of acutely nephrotic rats with antioxidant therapy did not attenuate interstitial inflammation or fibrosis. We speculate that other factors, possibly a consequence of proteinuria itself, are the predominant pathogenetic mediators of the tubulointerstitial damage in acute nephrotic syndrome.
Animals↗
The nephrotic syndrome: from the simple to the complex.
The nephrotic syndrome represents a series of physiological results ensuing from the occurrence of significant urinary loss of protein. Although the common initiating event of proteinuria has long been established, the list of problems that result has continued to grow as our understanding of the pathophysiology of nephrosis has increased. This article discusses this pathophysiology, emphasizing the consequences of nephrotic-range proteinuria. These consequences include not only acute and subacute manifestations of disrupted homeostasis, but also ways in which nephrosis itself may amplify mechanisms by which progressive renal nephron loss occurs. New insights into the factors that initiate and maintain glomerulosclerosis and interstitial fibrosis may offer potential approaches to preventing or ameliorating chronic renal insufficiency.
Child↗
Expulsion of uracil and thymine from the yeast Saccharomyces cerevisiae: contrasting responses to changes in the proton electrochemical gradient.
The outflow of uracil from the yeast Saccharomyces cerevisiae is known to be relatively fast in certain circumstances, to be retarded by proton conductors and to occur in strains lacking a uracil proton symport. In the present work, it was shown that uracil exit from washed yeast cells is an active process, creating a uracil gradient of the order of -80 mV relative to the surrounding medium. Glucose accelerated uracil exit, while retarding its entry. DNP or sodium azide each lowered the gradient to about -30 mV, simultaneously increasing the rate of uracil entry. They also lowered cellular ATP content. Manipulation of the external ionic conditions governing delta mu H+ at the plasma membrane had no detectable effect on uracil transport in yeast preparations thoroughly depleted of ATP. It was concluded that uracil exit is probably not driven by the proton gradient but may utilize ATP directly. It is known that thymine is not normally absorbed by yeast. However, thymine expulsion was here observed during deamination of the substrate 5-methylcytosine in the presence of glucose. In the absence of glucose, or following ATP depletion, thymine uptake from the medium only occurred when delta mu H+ was dissipated, either by DNP or azide, or by manipulation of the external ionic environment. The yeast expelled absorbed thymine when delta mu H+ was restored to the physiological range. The properties of the system corresponded to those of an H+/thymine antiport that is distinct from the mechanism expelling uracil.
Adenosine Triphosphate↗
Expression and function of monocyte chemoattractant protein-1 in experimental nephrotic syndrome.
This study investigates the expression and function of monocyte chemoattractant protein-1 (MCP-1) in rats with aminonucleoside nephrosis induced by a single intraperitoneal injection of puromycin aminonucleoside (PAN). On Day 7, PAN-treated rats had a sixfold increase in renal MCP-1 messenger (m)RNA levels and a twofold increase in interleukin-1 beta mRNA levels. During the course of PAN nephrosis, most of the de novo MCP-1 protein resembled protein droplets that were prominent in glomeruli between Days 3 and 14 and weaker but visible in tubules between Days 5 and 10. In addition, occasional tubules showed a cytoplasmic staining pattern for MCP-1. Two studies evaluated the effect of MCP-1 neutralization on renal monocyte recruitment. In the first study, PAN-treated rats were treated with affinity-purified MCP-1-neutralizing rabbit IgG on Days 0, 1, 3, and 5; kidneys were harvested on Day 7. There was no difference in the mean number of interstitial macrophages [119 +/- 28 vs 88 +/- 9 ED-1+ cells/1000 tubulointerstitial (TI) cells; 106 +/- 28 vs 119 +/- 33 Ia+ cells/1000 TI cells] or intraglomerular macrophages [2.0 +/- 0.9 vs 1.7 +/- 0.5 ED-1+ cells/glomerular cross section (gcs); 1.2 +/- 0.3 vs 1.1 +/- 0.4 Ia+ cells/gcs] compared with nephrotic rats treated with nonimmune rabbit IgG. In the second study, a group of PAN-treated rats was treated with MCP-1-neutralizing IgG administered continuously by an intraperitoneal miniosmotic pump for 7 days and was compared with a control group treated in an identical fashion with PAN and nonimmune IgG. On Day 7 there was no difference in the mean number of interstitial macrophages (55 +/- 45 vs 67 +/- 16 ED-1+ and 70 +/- 63 vs 61 +/- 13 Ia+ cells/1000 TI cells) and intraglomerular macrophages (1.0 +/- 0.4 vs 1.6 +/- 0.9 ED-1+ and 0.6 +/- 0.1 vs 1.1 +/- 0.7 Ia+ cells/gcs). The results of this study suggest that although MCP-1 gene and protein expression are increased in the kidneys of rats with aminonucleoside nephrosis, MCP-1 does not appear to play an essential role in early renal monocyte recruitment in this model.
Animals↗
Interstitial inflammation and fibrosis in rats with diet-induced hypercholesterolemia.
Abnormalities in lipid metabolism appear to play a pathogenic role in progressive renal disease. To elucidate the cellular and molecular basis of renal interstitial fibrosis in uninephrectomized rats with diet-induced hypercholesterolemia, we fed experimental rats with standard rat chow supplemented with 4% cholesterol and 1% cholic acid. Control rats were fed an isocaloric diet. Groups of 7 control and 7 experimental rats were killed after 4, 8, and 12 weeks. Hypercholesterolemic rats developed albuminuria; serum creatinine was elevated at 12 weeks. By 12 weeks numerous oil red O-positive cells were present throughout the interstitium and to a lesser extent in tubules. Total renal lipid-peroxidation products were significantly increased (172 +/- 15, 198 +/- 28, and 197 +/- 13 mmol malondialdehyde/kidney at 4, 8, and 12 weeks vs. 123 +/- 17, 144 +/- 6, and 125 +/- 10 mmol in controls). Immunostaining revealed oxidatively modified lipoproteins within tubular and interstitial cells. The interstitial disease was characterized by an interstitial infiltrate of monocytes. Significant increases were detected in renal cortical mRNA levels for monocyte chemoattractant protein-1 (MCP-1), osteopontin, and vascular cell adhesion molecule-1 (VCAM-1), associated with changes in the pattern of immunostaining for each encoded proteins. Total kidney collagen was significantly increased at 12 weeks (9.8 +/- 0.9 mg/kidney vs. 7.8 +/- 0.9 mg in controls). At 12 weeks there was a significant increase in interstitial immunostaining for collagen I, collagen III, collagen IV, fibronectin and tenascin. A significant threefold increase in renal cortical mRNA levels for transforming growth factor beta-1 (TGF-beta 1) at 4 and 12 weeks was associated with the appearance of TGF-beta 1-positive interstitial cells. Renal matrix protein mRNA levels were measured at 4, 8, and 12 weeks. The only statistically significant elevations were procollagen alpha 1(I) and procollagen alpha 1(III) at weeks 8 and 12. In contrast, renal cortical mRNA levels for the tissue inhibitor of metalloproteinases-1 (TIMP-1) were significantly increased at 4, 8 and 12 weeks (1.4 +/- 0.5, 2.7 +/- 0.9 and 2.7 +/- 1.4 arbitrary densitometric units, respectively, vs. 1.0 +/- 0.4, 1.0 +/- 0.5 and 1.0 +/- 0.4 units for controls), and urokinase-type plasminogen activator (muPA) mRNA levels were significantly decreased at 4, 8, and 12 weeks (0.4 +/- 0.1 arbitrary densitometric units for all three experimental groups vs. 1.0 +/- 0.4, 1.0 +/- 0.3, and 1.0 +/- 0.4 units for the control groups). In summary, rats with diet-induced hypercholesterolemia develop renal interstitial fibrosis over several weeks. Following the accumulation of lipids within tubulointerstitial cells, interstitial nephritis develops. The fibrotic phase is characterized by modest changes in matrix protein mRNA levels, up-regulated TIMP-1, and down-regulated muPA levels, suggesting that altered matrix degradation plays a role in the interstitial fibrogenesis in this model.
Actins↗
Cytosine accumulation as a measure of the proton electrochemical gradient acting on the overexpressed cytosine permease of Saccharomyces cerevisiae.
The magnitude of the proton gradient (delta mu H+) driving solute accumulation in Saccharomyces cerevisiae has long been in doubt, principally because of the lack of an agreed method for assaying its electrical component, the membrane potential (delta psi). In the present work, the size of the cytosine gradient (delta mu cyt) that the yeast generated was used as a measure of the driving gradient (delta mu H+). The selected yeast lacked cytosine deaminase and overexpressed cytosine permease, a 1 H+/cytosine system. delta mu cyt, assayed in washed cell suspensions fermenting glucose and containing 0.5 or 50 mM KCl, was about 260 mV at pH 4 or 5, falling to about 194 mV at pH 7. As a first estimate, -delta mu H+ was thus at least as large at the respective pH value. A 20 mM solution of the lipophilic cation tetraphenylphosphonium lowered delta mu cyt to a value roughly equal to the magnitude of the pH gradient (delta pH). A mathematical model was used to correct the first estimates of delta mu H+ for the effect of cytosine leakage outside the symport. In such a system, delta mu cyt cannot exceed the equivalent ratio Vmax/KmL, where Vmax and Km are kinetic parameters of the symport and L is the rate coefficient for leakage. The feasibility of assaying delta mu H+ depends on it not being much larger than that ratio. The model was tested successfully against observations made with yeast preparations depleted of ATP. After correction, -delta mu H+ during fermentation was estimated to be up to 25 mV larger than delta mu cyt and at least 70 mV larger than previous estimates in the literature involving lipophilic cations. From a knowledge of delta pH, delta psi was in turn deduced and compared with the maximum methylamine gradient (delta mu M) the yeast formed. The results supported the claim in the literature that, at acid pH, delta mu M is a measure of delta psi.
Biological Transport↗
Molecular insights into renal interstitial fibrosis.
Progressive interstitial fibrosis accompanied by loss of renal tubules and interstitial capillaries typifies all progressive renal diseases. Dynamic and complex, the process evidently overlaps with matrix remodeling; it may even be reversible. The interstitial fibrous tissue comprises several normal and novel matrix proteins, proteoglycans, and glycoproteins. Interstitial myofibroblasts are a major site of matrix protein overproduction, although resident fibroblasts, tubular cells, and inflammatory cells may contribute. Inadequate matrix degradation also appears to contribute to the fibrogenic process. Two protease cascades, the metalloproteinases and the plasminogen activator/ plasmin family of serine proteases, are implicated in the turnover of interstitial matrix proteins; upregulated expression of protease inhibitors has been observed in each. Increased tissue inhibitor of metalloproteinase-1 and plasminogen activator inhibitor-1 levels suggest that the intrinsic renal activity of the metalloproteinases and serine proteases are inhibited while matrix proteins accumulate in the interstitium. Several signals that may direct the interstitial fibrogenic process have been identified, but not yet proved to cause it. Upregulated expression of transforming growth factor beta-1, the proteotypic fibrogenic cytokine, has been observed in experimental and human models; it probably does not act alone. There may be supportive roles for platelet-derived growth factor, interleukin-1, basic fibroblast growth factor, angiotensin II, and endothelin-1. Although it is not known why interstitial fibrosis compromises renal function, atrophy of renal tubules may be pivotal. Ischemic necrosis and/or apoptosis may generate nonfunctioning atubular and sclerotic glomeruli. Future studies must delineate the molecular basis of the differences between renal repair and renal destruction by fibrosis, two processes that share many common features.
Animals↗
Expression of genes that promote renal interstitial fibrosis in rats with proteinuria.
The development of progressive tubular atrophy and interstitial fibrosis represents a final common pathway leading to renal insufficiency. My laboratory has been investigating several rat models of primary glomerular disease in an effort to determine cellular and molecular mechanisms of renal interstitial fibrosis. These models include puromycin aminonucleoside nephrosis (PAN), protein-overload proteinuria, passive Heymann nephritis, and diet-induced hypercholesterolemia. From a functional perspective, it is likely that the associated loss of tubules accounts for the decline in renal function. Four recurrent themes are emerging from our studies.
Animals↗
Neurologic manifestations of pediatric systemic lupus erythematosus.
Central nervous system involvement is a common but rarely reviewed feature of pediatric systemic lupus erythematosus (SLE). We retrospectively reviewed the charts of 91 patients with pediatric SLE and using a standardized data abstraction form documented 40 patients with central nervous system (CNS-SLE) involvement. The mean age of onset of SLE was 13.3 years. In 19 patients the CNS manifestation was a presenting symptom, in 12 patients CNS involvement was present within the first year of diagnosis, and in 9 patients it took up to 7 years for CNS disease to become evident. Nineteen children (48%) manifested neuropsychiatric SLE, which included depression, concentration or memory problems, and frank psychosis. Seizures were present in 8 patients (20%), 6 had cerebral ischemic events (15%), 1 had chorea (3%), 2 had papilledema (5%), and 2 patients had a peripheral neuropathy (5%). Nine patients (22%) had severe headache consistent with lupus headache. Seven children had more than one CNS manifestation. In the investigation of CNS-SLE, computed tomography and/or magnetic resonance imaging scans were helpful in patients with focal ischemic lesions and venous sinus thrombosis. Electroencephalography was abnormal only in 33% of patients with seizure disorders and rarely helpful in patients with diffuse neuropsychiatric symptoms. Single-photon emission computed tomography scans were abnormal in most patients with neuropsychiatric SLE, especially in those with frank psychosis. The lupus anticoagulant was present in the patient with chorea and was frequently present in patients with cerebral vascular events. Long-term outcome was good: only 1 child died of cerebral hemorrhagic infarction and 3 others had significant persistent CNS deficits. The majority of patients (90%) had excellent recovery from CNS-SLE.
Adolescent↗
Renal expression of genes that promote interstitial inflammation and fibrosis in rats with protein-overload proteinuria.
Rats with significant proteinuria induced by daily injections of bovine serum albumin develop interstitial inflammation and fibrosis. The present study was designed to investigate the molecular basis of interstitial monocyte (Mø) recruitment and early interstitial fibrosis. Groups of rats were sacrificed after one, two and three weeks. Despite an increase in interstitial Mø at week 1, whole kidney mRNA levels were not elevated for monocyte chemoattractant protein-1 (MCP-1), osteopontin or vascular cell adhesion molecule-1 (VCAM-1). Only osteopontin mRNA levels were significantly elevated in the renal cortex at four days. At two and three weeks, MCP-1 and osteopontin mRNA levels were increased and the proteins showed distinct tubular patterns of distribution. By immunostaining increased expression of VCAM-1 and intercellular adhesion molecule-1 (ICAM-1) was restricted to their presence or the surface of the interstitial inflammatory cells. TGF-beta 1 mRNA levels were increased at weeks 1, 2 and 3 (2.1, 2.9, 3.6x); interstitial and occasional cortical tubular cells expressed TGF-beta 1 mRNA and protein. There was a progressive rise in the number of cortical interstitial fields with increased staining for collagen (col) 1 (18, 29, 44%), col III (39, 61, 63%), col IV (7, 13, 29%), laminin (4, 10, 30%), fibronectin (14, 28, 37%), tenascin (19, 22, 14%) and in total renal col measured biochemically (1.1, 1.4, 2.0x) at weeks 1, 2 and 3, respectively. Renal matrix protein mRNA levels were variable and not always predictive of fibrosis. Only col I and tenascin levels were increased at week 1; all matrix protein mRNA levels except col IV were increased at week 2; but only tenascin, laminin and col IV mRNA levels remained elevated at three weeks. Plasminogen activator inhibitor-1 (PAI-1) and tissue inhibitor of metallo-proteinases (TIMP)-1 mRNA levels were significantly increased at two weeks. During the three weeks there was no change in urokinase, stromelysin or TIMP-3 mRNA levels. These results suggest that both increased matrix protein synthesis and altered matrix remodeling/degradation contribute to the final interstitial fibrogenic process in rats with protein-overload proteinuria. Mø, one of the sources of TGF-beta 1, infiltrate the interstitium by complex recruitment mechanisms which may depend in part on osteopontin, ICAM-1 and VCAM-1 expression.
Animals↗
Protein restriction reduces transforming growth factor-beta and interstitial fibrosis in nephrotic syndrome.
Nephrotic syndrome induced by puromycin aminonucleoside (PAN) is characterized by tubulointerstitial (TI) inflammation, foci of TI fibrosis, and increased renal mRNA levels for matrix genes, the tissue inhibitor of metalloproteinases (TIMP), and the transforming growth factor-beta 1 (TGF-beta 1). To investigate the ability of a low-protein diet known to decrease TI inflammation to alter the degree of renal fibrosis, we studied four groups of rats: 27% protein PAN, 27% protein control, 8% protein PAN, and 8% protein control. Renal TGF-beta 1 mRNA levels correlated with the number of interstitial macrophages (r = 0.76) and were significantly reduced by dietary protein restriction. On day 10, Northern blot analysis showed that the elevated renal mRNA levels for procollagens alpha 1 (I), alpha 1(III), and alpha 2(IV) and fibronectin in the PAN-treated rats were significantly reduced by 8% dietary protein. In contrast, genes regulating matrix degradation (stromelysin and TIMP) were relatively unchanged by the low-protein diet. The number of foci of interstitial fibrosis and total renal collagen were greater in the PAN + 27% protein group than in the control groups. Both parameters of fibrosis were partially normalized in the PAN + 8% protein group. The results of this study suggest that dietary protein restriction attenuates TI fibrosis in PAN-induced nephrosis by partially reversing the increase in renal matrix synthesis. This effect was associated with decreased renal expression of the fibrogenic cytokine TGF-beta 1, which may be partially mediated by the concomitant reduction in the number of interstitial inflammatory macrophages.
Animals↗