Biomedical subjects

R Largo

Publications and source records attributed to R Largo.

At least 19 recordsLinked to original sources

PubMed2006

Osteoporosis increases the severity of cartilage damage in an experimental model of osteoarthritis in rabbits.

OBJECTIVE: To evaluate the effect of osteoporosis (OP) in cartilage damage developed in an experimental model of osteoarthritis (OA) in mature female rabbits in order to investigate the relationship between OP and OA. METHODS: OA was experimentally induced by anterior cruciate section and partial medial meniscectomy in the left knee of 12 rabbits. OP was experimentally induced prior to OA in six rabbits by bilateral ovariectomy (OVX) and systemic corticosteroid administration during 4 weeks. Knees were evaluated with high resolution magnetic resonance imaging (MRI) before knee surgery to rule out any detrimental effect of corticosteroids on cartilage. Gross and microscopic cartilage changes were assessed 16 weeks after surgery in bilateral knees. Left knees were considered osteoarthritic or osteoarthritic plus osteoporotic. Right knees were used as osteoporotic and healthy controls, respectively. Bone mineral density (BMD) was measured with dual energy X-ray absorptiometry (DXA) at the lumbar spine, global knee and subchondral knee bone, and its variations correlated with cartilage abnormalities. RESULTS: MRI before knee surgery disclosed no cartilage or bone abnormalities in any of the studied groups. OP increased the severity of cartilage abnormalities in experimental knee OA significantly (P<0.05). Cartilage damage was inversely correlated with BMD variations measured at the lumbar spine (r=-0.74; P=0.015). BMD changes in global and subchondral knee bone also showed a trend to correlate inversely with cartilage damage. CONCLUSIONS: Prior induction of OP increases the severity of cartilage damage in experimental OA. Increase in cartilage damage correlates with bone loss. These findings suggest a direct relationship between OP and OA.

Absorptiometry, Photon↗

PubMed2006

Expression of the peptide C4b-binding protein beta in the arthritic joint.

BACKGROUND: C4b-binding protein (C4BP) is a plasma oligomeric glycoprotein that participates in the regulation of complement and haemostasis. Complement-regulatory activity depends on the C4BPalpha-polypeptide, whereas the C4BPbeta-polypeptide inactivates protein S, interfering with the anti-coagulatory protein C-dependent pathway. OBJECTIVE: To investigate the expression of C4BPbeta in the rheumatoid joint. METHODS: Expression of C4BP was studied in synovial explants from patients with rheumatoid arthritis, osteoarthritis and healthy controls, using immunohistochemistry and in situ hybridisation. C4BP isoforms and free C4BPbeta were studied in synovial effusions from patients with rheumatoid arthritis, osteoarthritis and microcrystalline arthritis (MCA) by immunoblotting; total and free protein S levels were studied by enzyme immunoassay. RESULTS: C4BPbeta was overexpressed in the synovial membranes of patients with rheumatoid arthritis, in close association with the severity of synovitis and the extension of interstitial fibrin deposits. As many as 85% fluids from patients with rheumatoid arthritis contained free C4BPbeta, whereas this unusual polypeptide was present in 50% fluids from patients with MCA and 40% fluids from patients with osteoarthritis. Free protein S at the effusions was pathologically reduced in patients with rheumatoid arthritis and MCA, and remained normal in patients with osteoarthritis. CONCLUSION: C4BPbeta is expressed by the inflamed synovial tissue, where it can participate in processes of tissue remodelling associated with invasive growth.

Adult↗

PubMed2006

Long term NSAID treatment inhibits COX-2 synthesis in the knee synovial membrane of patients with osteoarthritis: differential proinflammatory cytokine profile between celecoxib and aceclofenac.

OBJECTIVE: To compare the effect of celecoxib with that of a classic non-steroidal anti-inflammatory drug (NSAID) on synovial inflammation and on the synovial expression of proinflammatory genes in patients with knee osteoarthritis (OA). METHODS: 30 patients with severe knee OA scheduled for total knee replacement surgery were included in a 3 month clinical trial. They were randomised to two groups: patients treated with celecoxib (CBX) (200 mg/24 h) and patients treated with aceclofenac (ACF) (100 mg/12 h). Those patients with OA who did not want to be treated with NSAIDs served as a control group. During knee surgery, synovial fluid (SF) and synovial membrane (SM) were collected. A SM specimen was fixed and embedded in paraffin and another part was frozen for molecular biology studies. RESULTS: At the end of study both CBX and ACF treated patients showed a significant improvement in pain and knee function compared with controls. Both drugs significantly reduced prostaglandin E(2) (PGE(2)) SF concentration and down regulated COX-2 mRNA and protein expression at the SM. However, synovial macrophage infiltration (CD68 antigen staining) and expression of proinflammatory mediators, such as interleukin 1beta and tumour necrosis factor alpha, were decreased only by CBX treatment. CONCLUSION: Both drugs improved joint pain and function, inhibited SF PGE(2) concentration, and induced a decrease in synovial COX-2 expression and synthesis not related to the tissue inflammatory status. These data suggest that PGE(2) blocking agents may decrease PGE(2) production not only by direct COX-2 inhibition but also by down regulating COX-2 expression and synthesis. However, CBX and ACF appear to have different anti-inflammatory profiles in controlling OA synovial macrophage infiltration and proinflammatory expression.

Aged↗

PubMed2005

Bone mineral measurements of subchondral and trabecular bone in healthy and osteoporotic rabbits.

INTRODUCTION: Experimental models of osteoporosis in rabbits are useful to investigate anabolic agents because this animal has a fast bone turnover with predominant remodelling over the modelling processes. For that purpose, it is necessary to characterize the densitometric values of each type of bony tissue. OBJECTIVE: To determine areal bone mass measurement in the spine and in trabecular, cortical and subchondral bone of the knee in healthy and osteoporotic rabbits. DESIGN: Bone mineral content and bone mineral density were measured in lumbar spine, global knee, and subchondral and cortical bone of the knee with dual energy X-ray absorptiometry using a Hologic QDR-1000/W densitometer in 29 skeletally mature female healthy New Zealand rabbits. Ten rabbits underwent triplicate scans for evaluation of the effect of repositioning. Osteoporosis was experimentally induced in 15 rabbits by bilateral ovariectomy and postoperative corticosteroid treatment for 4 weeks. Identical dual energy X-ray absorptiometry (DXA) studies were performed thereafter. RESULTS: Mean values of bone mineral content at the lumbar spine, global knee, subchondral bone and cortical tibial metaphysis were: 1934+/-217 mg, 878+/-83 mg, 149+/-14 mg and 29+/-7.0 mg, respectively. The mean values of bone mineral density at the same regions were: 298+/-24 mg/cm(2), 455+/-32 mg/cm(2), 617+/-60 mg/cm(2) and 678+/-163 mg/cm(2), respectively. Bone mineral content and bone density of healthy rabbits followed a normal distribution at the four skeletal regions studied. Precision after triplicate repositioning yielded a coefficient of variation ranging from 2.6% to 3.8%. The least significant change ranged between 7.3% and 10.7%. Bone mineral density measured at the four different skeletal regions correlated significantly. Bone mineral density in osteoporotic rabbits was significantly lower in the four regions studied than that in controls, rendering a T-score of, respectively, -2.0+/-1.1 in the lumbar spine, -2.2+/-2.1 in the global knee, -1.9+/-0.6 in the subchondral bone, and -5.7+/-3.1 in the cortical tibia (P<0.05). CONCLUSIONS: DXA is a reliable and precise method to evaluate the bone mass in rabbits. Our results also suggest that subchondral bone is a bone of mixed densitometric characteristics with marked cortical bone predominance.

Absorptiometry, Photon↗

PubMed2004

Histopathological correlation of cartilage swelling detected by magnetic resonance imaging in early experimental osteoarthritis.

OBJECTIVE: We previously reported that an increase of cartilage thickness is the earliest measurable change by magnetic resonance imaging (MRI) in early stages of experimental osteoarthritis (OA). Our present objective was to study the microscopic translation of this finding in order to know whether the cartilage thickness increment represents the earliest structural damage or whether it alternatively constitutes a non-progressive reversible phenomenon. METHODS: OA was induced by partial medial meniscectomy in rabbits. Normal and sham-operated animals were used as controls. Gross and microscopic cartilage changes were sequentially assessed after surgery at 0, 2, 4, 6, 8, 10 and 52 weeks, and compared to MRI findings. RESULTS: The swelling of cartilage detected by MRI correlated with depletion in matrix proteoglycans and cellular loss, which were closely related to the progression of OA at the earliest stages. Abnormalities of the cartilage structure appeared only in advanced OA. CONCLUSION: Cartilage swelling detected by MRI is due to proteoglycan depletion and represents the earliest abnormality in OA. Because it is accompanied by cellular loss, it cannot be merely attributed to surgical trauma and represents true tissue damage. The biological meaning of volume variations detected by MRI should be assessed carefully taking into account the disease stage as an increase in cartilage height also reflects cartilage damage and not a reparative process.

Animals↗

PubMed2004

Sequential changes of parathyroid hormone related protein (PTHrP) in articular cartilage during progression of inflammatory and degenerative arthritis.

OBJECTIVE: To investigate immunolocalisation of parathyroid hormone related protein (PTHrP) in two sequential models of experimental cartilage damage (inflammatory and degenerative) in order to elucidate differences in chondrocyte response to the disease. METHODS: Immunohistochemistry with a polyclonal rabbit antiserum to the N-terminal domain of PTHrP was used to detect this protein in two different rabbit models sharing progressive cartilage damage: antigen induced arthritis (AIA) and osteoarthritis (OA) secondary to partial medial meniscectomy. Cartilage specimens from early (2 days in AIA; 8 weeks in experimental OA) and late (3 weeks in AIA; 52 weeks in OA) disease were compared. RESULTS: Cell and matrix PTHrP staining in early AIA and OA was similar to that in controls. Late AIA cartilage showed a significant decrease in PTHrP positive cells and in the cartilage matrix. In contrast, at late OA stages, distinct PTHrP positivity was detected in proliferating cell clones, as assessed by proliferating cell nuclear antigen staining around cartilage damaged areas. CONCLUSION: PTHrP staining of hyaline articular cartilage shows a different pattern during progression of each type of arthritis: an overall decrease associated with the inflammatory disease, and an increase in the proliferating chondrocyte clones with degenerative arthritis.

Animals↗

PubMed2004

EP2/EP4 signalling inhibits monocyte chemoattractant protein-1 production induced by interleukin 1beta in synovial fibroblasts.

BACKGROUND: Besides its proinflammatory properties, prostaglandin E(2) (PGE(2)) acts as a regulator of the expression of inducible genes. Inhibition of PGE(2) synthesis might thus result in a paradoxical deleterious effect on inflammation. OBJECTIVE: To examine the effect of PGE(2) on monocyte chemoattractant protein-1 (MCP-1) expression in cultured synovial fibroblasts (SF) stimulated with interleukin (IL)1beta. METHODS: MCP-1 expression was assessed in SF stimulated with IL1beta in the presence of PGE(2) or different NSAIDs by RT-PCR or northern blot and immunocytochemistry. Expression of cyclo-oxygenase (COX) isoforms was studied by western blot techniques. The role of PGE(2) receptors (EP) in PGE(2) action was assessed employing EP receptor subtype-specific agonists. RESULTS: PGE(2) significantly inhibited IL1beta induced MCP-1 expression in SF in a dose dependent manner. IL1beta increased COX-2 and did not alter COX-1 synthesis in SF. 11-Deoxy-PGE(1), an EP(2)/EP(4) agonist, reproduced PGE(2) action on MCP-1 expression. Butaprost, a selective EP(2) agonist, was less potent than PGE(2). Sulprostone, an EP(1)/EP(3) agonist, had no effect on IL1beta induced MCP-1 expression. Inhibition of endogenous PGE(2) synthesis by NSAIDs further enhanced MCP-1 mRNA expression in IL1beta stimulated SF, an effect prevented by addition of exogenous PGE(2). CONCLUSION: Activation of EP(2)/EP(4) receptors down regulates the expression of MCP-1 in IL1beta stimulated SF, while PGE(2) pharmacological inhibition cuts off this signalling pathway and results in a superinduction of MCP-1 expression. The data suggest that NSAIDs may intercept a natural regulatory circuit controlling the magnitude of inflammation, which questions their continuous administration in inflammatory joint diseases.

Animals↗

PubMed2003

Glucosamine inhibits IL-1beta-induced NFkappaB activation in human osteoarthritic chondrocytes.

OBJECTIVE: Glucosamine sulfate (GS) is a commonly used drug for the treatment of osteoarthritis. The mechanism of the action of this drug does, however, remain to be elucidated. In human osteoarthritic chondrocytes (HOC) stimulated with a proinflammatory cytokine, we studied whether GS could modify the NFkappaB activity and the expression of COX-2, a NFkappaB-dependent gene. METHODS: Using HOC in culture stimulated with interleukin-1 beta (IL-1beta), the effects of GS on NFkappaB activation, nuclear translocation of NFkappaB/Rel family members, COX-1 and COX-2 expressions and syntheses and prostaglandin E2 (PGE2) concentration were studied. RESULTS: GS significantly inhibited NFkappaB activity in a dose-dependent manner, as well as the nuclear translocation of p50 and p65 proteins. Furthermore, GS-preincubated IL-1beta-stimulated HOC showed an increase in IkappaBalpha in the cell cytoplasm in comparison with HOC incubated with IL-1beta alone. GS also inhibited the gene expression and the protein synthesis of COX-2 induced by IL-1beta, while no effect on COX-1 synthesis was seen. GS also inhibited the release of PGE2 to conditioned media of HOC stimulated with IL-1beta. CONCLUSIONS: GS inhibits the synthesis of proinflammatory mediators in HOC stimulated with IL-1beta through a NFkappaB-dependent mechanism. Our study further supports the role of GS as a symptom- and structure-modifying drug in the treatment of OA.

Acetylglucosamine↗

PubMed2003

Fibrin generated in the synovial fluid activates intimal cells from their apical surface: a sequential morphological study in antigen-induced arthritis.

OBJECTIVE: Fibrin deposits adhered to the synovial surface are typical of rheumatoid joints. Since fibrin appears to have a role in arthritis perpetuation our aim was to investigate how these deposits are formed and the consequences of their adhesion to the tissue. METHODS: The appearance of fibrin aggregates either free in the synovial fluid or attached to the membrane was studied in rabbits with antigen-induced arthritis by histological techniques at different time points from challenge. In the fixed synovial membranes areas of fibrin-bound synovium were evaluated by qualitative variables to obtain a sequential profile of morphological changes. RESULTS: Fibrin aggregates appeared from the initial stages of the disease in the synovial effusion. Later on, they were localized on the synovial surface and progressive changes were noted at the fibrin-tissue interface, ending with the invasion of the aggregates by synovial cells and their incorporation into the tissue. CONCLUSION: Fibrin aggregates generated inside the joint cavity may constitute a source of activation and acquisition of invasiveness of the synovial fibroblasts, a process to explore within the perpetuating mechanisms of rheumatoid arthritis.

Animals↗

PubMed2003

A fibrin based model for rheumatoid synovitis.

Intracavitary fibrin clots may initiate pannus formation and the immunopathology of RA. Two critical steps, probably host dependent, may determine the development of RA: an altered regulation of extravascular haemostasis or an aberrant reactivity of synovial fibroblasts to the adhered fibrin clots. Current treatments for RA target events downstream of fibrin deposition, perhaps agents acting at an earlier stage should be tried.

Arthritis, Rheumatoid↗

PubMed2002

Modulation of cell recruitment by anti-inflammatory agents in antigen-induced arthritis.

OBJECTIVE: To study the effect of meloxicam (MXC) and diclofenac (DCF) on the recruitment of leucocytes during acute experimental arthritis. METHODS: Rabbits with antigen-induced arthritis were treated with MXC, DCF, or not treated. After 48 hours, synovial fluid (SF) leucocyte influx and prostaglandin E(2) (PGE(2)) levels were evaluated. Interleukin 8 (IL8) and monocyte chemotactic peptide-1 (MCP-1) expression and synthesis were studied in the inflamed tissues. RESULTS: Arthritic knees showed synovial effusion with a high leucocyte count and PGE(2) concentration, and an increased expression of IL8 and MCP-1. Both non-steroidal anti-inflammatory drugs (NSAIDs) reduced PGE(2) levels and the polymorphonuclear cell (PMN) concentration in SF, while the mononuclear cell (MN) concentration was unchanged in the treated groups in comparison with controls. A definite reduction of IL8 levels was obtained with the treatments, but the drugs did not prevent the up regulation of MCP-1. CONCLUSION: The effect of these NSAIDs in acute arthritis may be related to the down regulation of IL8 production. The results suggest a differential effect of anti-inflammatory drugs on PMN and MN recruitment to the joint.

Animals↗

PubMed2001

Mycophenolate mofetil prevents salt-sensitive hypertension resulting from angiotensin II exposure.

BACKGROUND: Interstitial mononuclear cell infiltration is a feature of experimental models of salt-sensitive hypertension (SSHTN). Since several products of these cells are capable of modifying local vascular reactivity and sodium reabsorption, we investigated whether mycophenolate mofetil (MMF), a drug known to inhibit infiltration and proliferation of immune cells, would modify the SSHTN induced by angiotensin II (Ang II) infusion. METHODS: Sprague-Dawley rats received Ang II for two weeks using subcutaneous minipumps. A high-sodium (4% NaCl) diet was started on the third week and was maintained until the eighth week. MMF (30 mg/kg, N = 15), an immunosuppressive drug, or vehicle (N = 15) was given daily by gastric gavage during the initial three weeks. Sham-operated rats (N = 9) were used as controls. Body weight, blood pressure (tail-cuff plethysmography), and serum creatinine were determined weekly. Urinary malondialdehyde (MDA) excretion, renal histology, and immunohistology, including the presence of Ang II and superoxide-producing cells, were analyzed at the end of Ang II infusion and at eight weeks. RESULTS: MMF treatment did not modify hypertension induced during exogenous Ang II infusion, but prevented the subsequent SSHTN. Tubulointerstitial injury resulting from Ang II infusion was significantly reduced by MMF treatment, as were proliferative activity, T-cell infiltration and activation (interleukin-2 receptor expression), superoxide-producing cells, and urinary MDA excretion. Ang II-producing cells were present in the renal tubulointerstitium of rats with SSHTN (60 +/- 30 Ang II-positive cells/mm(2) at 8 weeks) and were reduced by two thirds in the MMF-treated group. Forty percent of lymphocytes infiltrating the tubulointerstitium stained positive for Ang II. The expression of Ang II receptors in the kidney was unmodified. CONCLUSIONS: SSHTN resulting from Ang II infusion is associated with infiltration and activation of immune cells that produce Ang II. MMF treatment reduces these features and prevents the development of SSHTN.

Angiotensin II↗

PubMed2001

Up-regulation of parathyroid hormone-related protein in folic acid-induced acute renal failure.

BACKGROUND: Parathyroid hormone (PTH)-related protein (PTHrP) is present in many normal tissues, including the kidney. Current evidence supports that PTHrP is involved in renal pathophysiology, although its role on the mechanisms of renal damage and/or repair is unclear. Our present study examined the changes in PTHrP and the PTH/PTHrP receptor (type 1) in folic acid-induced acute renal failure in rats. The possible role of PTHrP on the process of renal regeneration following folic acid administration, and potential interaction between angiotensin II (Ang II) and endothelin-1, and PTHrP, were examined in this animal model. METHODS: PTHrP, PTH/PTHrP receptor, ACE, and preproendothelin-1 (preproET-1) mRNA levels in the rat kidney were analyzed by reverse transcription-polymerase chain reaction (RT-PCR) and/or RNase protection assay. Immunohistochemistry also was performed for PTHrP, the PTH/PTHrP receptor, and Ang II in the renal tissue of folic acid-injected rats. The role of PTHrP on tubular cell proliferation following folic acid injury was investigated in vitro in rat renal epithelial cells (NRK 52E). PTHrP secretion in the medium conditioned by these cells was measured by an immunoradiometric assay specific for the 1-36 sequence. RESULTS: Using RT-PCR, PTHrP mRNA was rapidly (1 hour) and maximally increased (3-fold) in the rat kidney after folic acid, decreasing after six hours. At 72 hours, renal function was maximally decreased in these rats, associated with an increased PTHrP immunostaining in both renal tubules and glomeruli. In contrast, the PTH/PTHrP receptor mRNA (RNase protection assay) decreased shortly after folic acid administration. Moreover, PTH/PTHrP receptor immunostaining dramatically decreased in renal tubular cell membranes after folic acid. A single subcutaneous administration of PTHrP (1-36), 3 or 50 microg/kg body weight, shortly after folic acid injection increased the number of tubular cells staining for proliferating cell nuclear antigen by 30% (P < 0.05) or 50% (P < 0.01), respectively, in these rats at 24 hours, without significant changes in either renal function or calcemia. On the other hand, this peptide failed to modify the increase (2-fold over control) in ACE mRNA, associated with a prominent Ang II staining into tubular cell nuclei, in the kidney of folic acid-treated rats at this time period. The addition of 10 mmol/L folic acid to NRK 52E cells caused a twofold increase in PTHrP mRNA at six hours, without significant changes in the PTH/PTHrP receptor mRNA. The presence of two anti-PTHrP antibodies, with or without folic acid, in the cell-conditioned medium decreased (40%, P < 0.01) cell growth. CONCLUSIONS: Renal PTHrP was rapidly and transiently increased in rats with folic acid-induced acute renal failure, featuring as an early response gene. In addition, changes in ACE and Ang II expression were also found in these animals. PTHrP induces a mitogenic response in folic acid-damaged renal tubular cells both in vivo and in vitro. Our results support the notion that PTHrP up-regulation participates in the regenerative process in this model of acute renal failure and is a common event associated with the mechanisms of renal injury and repair.

Acute Kidney Injury↗

PubMed2001

Mycophenolate mofetil prevents salt-sensitive hypertension resulting from nitric oxide synthesis inhibition.

Recent studies have suggested that subtle microvascular and tubulointerstitial injury in the kidney can cause salt-sensitive hypertension. To test this hypothesis, we determined whether the mild renal disease induced by transient blockade of nitric oxide (NO) synthesis would result in salt-sensitive hypertension and whether prevention of the renal injury by coadministration of the immunosuppressive agent mycophenolate mofetil (MMF) would block the development of salt sensitivity. N(omega)-nitro-L-arginine-methyl ester (L-NAME; 70 mg/100 ml in the drinking water) was administered for 3 wk to rats with or without MMF (30 mg x kg(-1) x day(-1) by gastric gavage), followed by a 1-wk "washout" period in which the MMF was continued, which was followed in turn by placement on a high-salt (4% NaCl) diet for an additional 4 wk. Renal histology was examined at 3 and 8 wk, and blood pressure was measured serially. L-NAME treatment resulted in acute hypertension and the development of mild renal injury. During the washout period, blood pressure returned to normal, only to return to the hypertensive range on exposure of the animals to a high-salt diet. MMF treatment prevented the development of hypertension in response to a high-salt diet. This correlated with the ability of MMF to inhibit specific aspects of the renal injury, including the development of segmental glomerulosclerosis, the infiltration of T cells and ANG II-positive cells, and the thickening of afferent arterioles.

Animals↗

PubMed2001

Activation of NF-kappaB in tubular epithelial cells of rats with intense proteinuria: role of angiotensin II and endothelin-1.

The mechanisms by which persistent proteinuria induces interstitial inflammation and fibrosis are not well known, although nuclear factor-kappaB (NF-kappaB), which regulates the transcription of many genes involved in renal injury, could be implicated. In rats with intense proteinuria, we studied the renal activation of NF-kappaB as well as the potential involvement of the vasoactive hormones angiotensin II (Ang II) and endothelin-1 (ET-1). Uninephrectomized Wistar-Kyoto rats receiving 1 g/d of BSA had proteinuria but no renal morphological lesions at day 1. By contrast, tubular atrophy and/or dilation and mononuclear cell infiltration were observed after 8 or 28 days of BSA administration, coinciding with maximal proteinuria. In relation to control uninephrectomized rats, the renal cortex of nephritic rats showed an increment in the activation of NF-kappaB at all time periods studied. By in situ Southwestern histochemistry, NF-kappaB activity was mainly localized in proximal tubules, interstitial mononuclear cells, and, to a lesser extent, the glomeruli. The administration of the ACE inhibitor quinapril plus the ET(A)/ET(B) receptor antagonist bosentan during 28 days to BSA-overloaded animals diminished proteinuria, renal lesions, and NF-kappaB activity more markedly than single drugs. Cultured tubular epithelial cells exposed to BSA revealed an intense NF-kappaB activation in a time- and dose-dependent manner. Incubation of cells with receptor antagonists of Ang II (AT(1): losartan and AT(2): PD-123,319) or ET-1 (ET(A): BQ123 and ET(B): IRL1038) inhibited significantly the BSA-induced NF-kappaB activity (90%, 75%, 90%, and 60% of inhibition versus basal, respectively). Our results show that overload proteinuria causes NF-kappaB activation in tubular epithelial cells both in vivo and in vitro. The vasoactive peptides Ang II and ET-1 appear to be implicated in this effect. The results reveal a novel mechanism of perpetuation of renal damage induced by persistent proteinuria.

Analysis of Variance↗

PubMed1999

Short stature, myopia, severe developmental delay, and peculiar facial appearance in two brothers: a new syndrome?

We report on 2 brothers with short stature, microcephaly, myopia, retarded osseous maturation, severe developmental delay, and minor anomalies including temporal narrowing, periorbital fullness, full cheeks in infancy, and protruding lower lip. Both brothers and their parents had normal chromosomes. Fluorescence in situ hybridization with probes from all (sub-)telomeric chromosomal regions excluded a structural rearrangement involving telomeric segments. Because the pattern of congenital abnormalities is not like that of any well-known multiple congenital anomaly/mental retardation syndrome, we suggest a previously undescribed syndrome of autosomal recessive or X-linked inheritance.

Adult↗

PubMed1999

Renal expression of parathyroid hormone-related protein (PTHrP) and PTH/PTHrP receptor in a rat model of tubulointerstitial damage.

BACKGROUND: PTHrP, which appears to act as a growth/differentiation factor in a variety of tissues, is present in the kidney; however, its role is unclear. METHODS: The expression of PTHrP and the PTH/PTHrP receptor were investigated by reverse transcription-polymerase chain reaction (RT-PCR) and immunohistochemistry in the remnant kidney of uninephrectomized (UNX) rats after protein overloading [1 g/day of bovine serum albumin (BSA)]. RESULTS: Compared with UNX-control rats, proteinuria in BSA-overloaded animals was detected within the first 24 hours and increased during the entire study period (28 days). Kidney examination by light microscopy showed no significant renal lesions at day 1 of BSA treatment, whereas at days 8 and 28, tubular lesions, infiltration of mononuclear cells, and mesangial expansion were observed. PTHrP mRNA expression in the renal cortex was already increased at day 1 (fourfold) and plateaued between days 8 and 28 (12- and 15-fold, respectively) in BSA-overloaded animals compared with UNX-control rats. At day 8, immunohistochemical analysis with two different anti-PTHrP antibodies showed a dramatic increase of PTHrP staining in the damaged proximal and distal tubules from BSA-overloaded rats with respect to UNX-control rats. Moreover, intense PTHrP immunostaining was also observed in glomerular mesangial and endothelial cells in BSA-overloaded rats, but not in the UNX-control rats. A reciprocal decrease of PTH/PTHrP receptor mRNA and immunostaining, without significant changes in the cellular localization (proximal and distal tubule, and glomerular mesangial and epithelial cells) of the PTH/PTHrP receptor positivity was found to occur in the renal cortex of BSA-overloaded rats. At day 8, coinciding with the up-regulation of PTHrP, an increase in the angiotensin converting enzyme and preproendothelin-1 gene expression was observed in the renal cortex of BSA-overloaded rats compared with UNX-control rats. CONCLUSIONS: These results indicate that PTHrP can be added to the group of genes that are up-regulated in proximal tubular cells in response to intense proteinuria. Our results, together with previous findings, suggest that the vasoactive hormones angiotensin II and endothelin-1 could participate in the PTHrP production in the renal cortex of BSA-overloaded rats. Further experiments are required to clarify the mechanisms of PTHrP up-regulation and its possible role in the response to renal damage in this animal model.

Animals↗

PubMed1999

Angiotensin-converting enzyme is upregulated in the proximal tubules of rats with intense proteinuria.

Persistent proteinuria is considered a deleterious prognostic factor in most progressive renal diseases. However, the mechanisms by which proteinuria induces renal damage remain undetermined. Since proximal tubular cells possess all the machinery to generate angiotensin II (Ang II), we approached the hypothesis that proteinuria could elicit the renal activation of the renin-angiotensin system in a model of intense proteinuria and interstitial nephritis induced by protein overload. After uninephrectomy (UNX), Wistar-Kyoto rats received daily injections of 1 g BSA or saline for 8 days. The mean peak of proteinuria was observed at the fourth day (538+/-89 versus 3+/-1 mg/24 h in UNX controls; n=12; P<0.05) and was increased during the whole study period (at the eighth day: 438+/-49 mg/24 h; n=12; P=NS). Morphological examination of the kidneys at the end of the study showed marked tubular lesions (atrophy, vacuolization, dilation, and casts), interstitial infiltration of mononuclear cells, and mesangial expansion. In relation to UNX control rats, renal cortex of BSA-overloaded rats showed an increment in the gene expression of angiotensinogen (2.4-fold) and angiotensin-converting enzyme (ACE) (2.1-fold), as well as a diminution in renin gene expression. No changes were observed in angiotensin type 1 (AT1) receptor mRNA expression in both groups of rats. By in situ reverse transcription-polymerase chain reaction and immunohistochemistry, ACE expression (gene and protein) was mainly localized in proximal and distal tubules and in the glomeruli. By immunohistochemistry, angiotensinogen was localized only in proximal tubules, and AT1 receptor was localized mainly in proximal and distal tubules. In the tubular brush border, an increase in ACE activity was also seen (5. 5+/-0.5 versus 3.1+/-0.7 U/mg protein x10(-4) in UNX control; n=7; P<0.05). Our results show that in the kidney of rats with intense proteinuria, ACE and angiotensinogen were upregulated, while gene expression of renin was inhibited and AT1 was unmodified. On the whole, these data suggest an increase in Ang II intrarenal generation. Since Ang II can elicit renal cell growth and matrix production through the activation of AT1 receptor, this peptide may be responsible for the tubulointerstitial lesions occurring in this model. These results suggest a novel mechanism by which proteinuria may participate in the progression of renal diseases.

Animals↗