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Biomedical subjects

B H Rovin

Publications and source records attributed to B H Rovin.

At least 19 recordsLinked to original sources
PubMed2006

Consumption of erythrocyte CR1 (CD35) is associated with protection against systemic lupus erythematosus renal flare.

Erythrocyte complement receptor type one (E-CR1) is thought to protect against immune complex (IC) disease through interactions that lead to E-CR1 consumption, and low E-CR1 levels are characteristic of systemic lupus erythematosus (SLE). The purpose of this study was to test the hypothesis that E-CR1 consumption can predict or mark SLE flare. Recurrently active SLE patients [n = 43; 28 with past or present major renal manifestations (SLER) and 15 without (SLENR)], were evaluated every 2 months by detailed protocol testing (mean follow-up 22 months), including direct measurements of E-CR1 levels using a radioimmunoassay. In all patients, detectable E-CR1 levels fluctuated widely through acute periods of consumption and regeneration, preventing the use of any single value as a baseline. However, when individual chronic baseline values were used, determined as the mean of all E-CR1 values 4 months or more from a flare, a clear trend was observed. In 16 of 16 instances of non-renal flare in SLER patients, E-CR1 levels decreased at flare (mean decrease 34%, P < 0.0001). In contrast, no consistent difference was observed for flare in SLENR patients or for renal flare in SLER patients. Changes in E-CR1 levels did not correlate with plasma CR1 levels. In conclusion, single occurrences of E-CR1 consumption did not generally predict or mark SLE flare. However, compared to the average E-CR1 levels measured during no-flare intervals, E-CR1 consumption in SLER patients at flare was strongly associated with freedom from signs of renal involvement. We postulate that E-CR1 consumption reflects E-CR1 function that includes protecting against SLE nephritis.

Complement C3↗
PubMed2006

Differentiation-dependent regulation of the cyclooxygenase cascade during adipogenesis suggests a complex role for prostaglandins.

AIM: A thorough understanding of the mechanisms of adipocyte differentiation and metabolism is important for the prevention and/or treatment of obesity and its complications, including type 2 diabetes mellitus. A complex role for prostaglandins (PGs) in adipogenesis is suggested. We examined the expression and cellular localization of enzymes in the cyclooxygenase (COX) cascade that synthesize PGs as well as the PG profile as a function of differentiation status in 3T3-L1 cells. METHODS: Murine 3T3-L1 preadipocytes were used as a model for studies of adipocyte differentiation induced by a hormone cocktail and compared with the parental fibroblastic line NIH 3T3. Both cell lines were incubated in maintenance medium or differentiation medium. Nine days after differentiation, the expression of enzymes in the COX cascade was evaluated by immunoblot analysis, reverse transcriptase-polymerase chain reaction (RT-PCR) and immunocytochemistry, and PG formation was examined using enzyme immunoassay. RESULTS: A differentiation-dependent diminution of COX-1 and COX-2 mRNA and cognate proteins in 3T3-L1 cells was observed. PG release, including PGE(2), 6-keto PGF(1alpha), PGD(2) and 15d-PGJ(2), significantly decreased following differentiation in 3T3-L1 cells (anova/Tukey, p < 0.05). However, microsomal PGE synthase (mPGES) and lipocalin-type PGD synthase (L-PGDS) were selectively upregulated. Immunocytochemistry revealed that COX-1 and COX-2 became intracellularly more diffuse upon differentiation, whereas mPGES was redistributed to the nuclear compartment. CONCLUSIONS: Regulation of PG formation and COX-2 expression in 3T3-L1 cells is differentiation-dependent and involves changes in the levels of gene expression of the individual isoforms as well as redistribution of the enzymes within cellular compartments.

3T3-L1 Cells↗
PubMed2001

A cyclopentenone prostaglandin activates mesangial MAP kinase independently of PPARgamma.

The mitogen-activated protein (MAP) kinases mediate the response of renal glomerular mesangial cells to a variety of physiologic and pathologic stimuli. This investigation examines the effect of the cyclopentenone prostaglandin 15-deoxy-delta(12,14)-prostaglandin J2 (15d-PGJ2) on MAP kinases in human mesangial cells. We show that 15d-PGJ2 dose-dependently increases the extracellular signal-regulated kinase (ERK) activity of human mesangial cells, but has no effect on Jun-NH2-terminal kinase or p38 MAP kinase. Despite the fact that 15d-PGJ2 is a peroxisome proliferator-activated receptor (PPAR) ligand, and PPARgamma is shown to be expressed by mesangial cells, the thiazolidinedione PPARgamma agonist ciglitazone does not activate ERK. Additionally, a synthetic PPARgamma antagonist does not attenuate the activation of ERK by 15d-PGJ2. 15d-PGJ2-mediated ERK activation is however blocked by the MEK inhibitor PD 098059, appears to require phosphatidylinositol-3 kinase, but is independent of protein kinase C activation. These results demonstrate a novel effect of 15d-PGJ2 to induce ERK in human mesangial cells independently of PPARgamma.

Cells, Cultured↗
PubMed2001

Renoprotection: one or many therapies?

BACKGROUND: Renal disease that progresses to end-stage renal disease (ESRD) imposes a great burden on the affected individual and on society, which mainly bears the cost of ESRD (currently more than $10 billion to treat about 333,000 patients annually in the U.S.). Thus, there is a great need to identify therapies that arrest the progression mechanisms common to all forms of renal disease. Progress is being made. Perhaps the most visible advance is the randomized controlled trials (RCT) demonstrating the renoprotective effects of angiotensin-converting enzyme (ACE) inhibitors. There are also numerous other promising renoprotective therapies. Unfortunately, testing each therapy in RCT is not feasible. Thus the nephrologist has two choices: restrict renoprotective therapy to those shown to be effective in RCT, or expand the use of renoprotective therapies to include those that, although unproven, are plausibly effective and prudent to use. The goal of this work is to provide the documentation needed for the nephrologist to choose between these strategies. METHODS: This work first describes the mechanisms believed to be involved in the progression of renal disease. Based largely on this information, 18 separate interventions that slow the progression are described. Each intervention is assigned a level of recommendation (Level 1 is the highest and Level 3 the lowest) according to the strength of evidence supporting its renoprotective efficacy. RESULTS: The number of interventions at each level of recommendation are: Level 1, N = 4; Level 2, N = 4; Level 3, N = 10. Our own experience with the multiple-risk-factor intervention is that most patients can achieve the majority of the Level 1 and 2 interventions, and many of the Level 3 interventions. We recommend the expanded renoprotection strategy. CONCLUSION: This work advances the hypothesis that, until better information becomes available, a broad-based, multiple-risk-factor intervention intended to slow the progression of renal disease can be justified in those with progressive nephropathies. This work is intended primarily for clinical nephrologists and thus each recommended intervention is described in substantial practical detail.

Disease Progression↗
PubMed2001

Of mice and men: the relevance of the mouse to the study of human SLE.

A number of mouse models have been utilized to study the pathophysiology of immune complex (IC) disease, and the hallmark IC disease systemic lupus erythematosus (SLE). Many of these studies have provided exciting new insights into IC-mediated inflammation and autoimmunity. However, numerous differences exist between mice and humans that suggest that mouse studies are not always applicable to human disease. These differences can be found in the biological systems that interact with circulating IC, in the specifics of disease presentation, and in the general physiology of the two species. Furthermore, although the mechanisms of SLE-like autoimmune disease in the mouse are being defined through analyses of the murine models of SLE, it remains to be proven that these mechanisms are relevant to human SLE. Thus, generalizing the results of the mouse studies to human SLE and other human IC diseases must be done with caution.

Animals↗
PubMed2001

Lymphocytes induce monocyte chemoattractant protein-1 production by renal cells after Fc gamma receptor cross-linking: role of IL-1beta.

Leukocyte recruitment to the kidney in immune complex disease like systemic lupus erythematosus (SLE) is mediated in part by local expression of chemokines such as monocyte chemoattractant protein-1 (MCP-1). Recent studies from this laboratory demonstrated that cross-linking Fc gammaR on lymphocytes causes release of a soluble factor that induces monocyte chemokine production. To explain the induction of renal chemokine expression in immune complex disease, we postulated that this lymphocyte factor stimulates renal parenchymal cell MCP-1 expression. To test this hypothesis, human peripheral blood lymphocytes were incubated on immobilized IgG, a model for immune complex Fc gammaR cross-linking. Supernatants from these lymphocyte cultures significantly increased MCP-1 production by human mesangial, glomerular capillary endothelial, and proximal tubular epithelial cells. Mesangial cells incubated on immobilized IgG or with soluble, preformed immune complexes did not secrete MCP-1 above control levels. Lymphocyte supernatant-induced MCP-1 production appeared to be dependent on the presence of interleukin (IL)-1beta in the supernatant. Removing IL-1beta from the supernatants, antagonizing its activity, or preventing conversion to mature IL-1beta abrogated renal cell MCP-1 expression by the lymphocyte supernatants. These data demonstrate that in response to cross-linking Fc gammaR, lymphocytes induce renal cell MCP-1 expression by secreting IL-1beta. Renal chemokine expression in immune complex disease may thus be triggered as lymphocytes traffic through the kidney and encounter deposited immune complexes.

Antigen-Antibody Complex↗
PubMed2000

Chemokine blockade as a therapy for renal disease.

Chemokines have been verified as inflammatory mediators of experimental nephritis by using anti-chemokine antibodies, chemokine receptor antagonists or targeted chemokine gene disruption. In human disease, chemokines are expressed in the kidney in association with inflammatory infiltrates. Chemokine blockade is thus a potentially novel approach to therapy of inflammatory renal disease. Several anti-chemokine strategies are under development. Effective use of anti-chemokine therapy for renal disease will require a precise understanding of the unique roles that individual chemokines have in renal pathology, and the genetic factors that regulate chemokine expression.

Chemokines↗
PubMed1999

A novel polymorphism in the MCP-1 gene regulatory region that influences MCP-1 expression.

Two novel polymorphisms in the distal regulatory region of the MCP-1 gene were identified by directly sequencing PCR amplified genomic DNA. These polymorphisms are located at positions -2518 (G or A) and -2076 (A or T) relative to the major transcriptional start site of the gene. To examine the effect of these polymorphisms on MCP-1 transcription, polymorphic variants of the MCP-1 distal regulatory region were placed upstream of a luciferase reporter gene and transfected into A172 cells. IL-1beta-induced luciferase activity was significantly greater from cells transfected with constructs containing G at position -2518. The polymorphism at -2076 did not affect MCP-1 transcription. IL-1beta-treated peripheral blood mononuclear cells from individuals heterozygous or homozygous for G at -2518 produced more MCP-1 than cells from individuals homozygous for A at -2518. These data identify a polymorphism in the MCP-1 distal regulatory region that affects the level of MCP-1 expression in response to an inflammatory stimulus.

Alleles↗
PubMed1999

The mitogen-activated protein kinase p38 is necesssary for interleukin 1beta-induced monocyte chemoattractant protein 1 expression by human mesangial cells.

Mitogen-activated protein (MAP) kinases have been suggested as potential mediators for interleukin 1beta (IL-1beta)-induced gene activation. This study investigated the role of the MAP kinases p38 and ERK2 in IL-1beta-mediated expression of the chemokine MCP-1 by human mesangial cells. Phosphorylation of p38 kinase, which is necessary for activation, increased significantly after IL-1beta treatment. p38 kinase immunoprecipitated from IL-1beta-treated cells phosphorylated target substrates to a greater extent than p38 kinase from controls. SB 203580, a selective p38 kinase inhibitor, was used to examine the role of p38 kinase in MCP-1 expression. SB 203580 decreased IL-1beta-induced MCP-1 mRNA and protein levels, but did not affect MCP-1 mRNA stability. Because NF-kappaB is necessary for MCP-1 gene expression, the effect of p38 kinase inhibition on IL-1beta induction of NF-kappaB was measured. SB 203580 (up to 25 microM) had no effect on IL-1beta-induced NF-kappaB nuclear translocation or DNA binding activity. Our previous work showed that IL-1beta also activates the MAP kinase ERK2 in human mesangial cells. PD 098059, a selective inhibitor of the ERK activating kinase MEK1, had no effect on IL-1beta-induced MCP-1 mRNA or protein levels, or on IL-1beta activation of NF-kappaB. These data indicate that p38 kinase is necessary for the induction of MCP-1 expression by IL-1beta, but is not involved at the level of cytoplasmic activation of NF-kappaB. In contrast, ERK2 does not mediate IL-1beta induced MCP-1 gene expression.

Calcium-Calmodulin-Dependent Protein Kinases↗
PubMed1998

Lymphocytes produce IL-1beta in response to Fcgamma receptor cross-linking: effects on parenchymal cell IL-8 release.

Neutrophils mediate tissue injury in response to immune complexes, although the factors that induce their recruitment are incompletely understood. We have reported that lymphocytes may be important regulators of monocyte and macrophage IL-8 release in the presence of immobilized IgG. Since tissue parenchymal cells are important local producers of IL-8 but are not directly stimulated by FcgammaR cross-linking, we hypothesized that lymphocytes may also regulate parenchymal IL-8 release. Supernatants from lymphocytes incubated on immobilized IgG induced primary human fibroblasts and human mesangial cells to produce IL-8 (17 +/- 3.5 and 44 +/- 8 ng/ml, respectively). Fibroblast and mesangial cell IL-8 mRNA levels were similarly increased by the conditioned lymphocyte supernatant. Immobilized anti-human FcgammaRIII, but not FcgammaRI or FcgammaRII Abs, could stimulate this IL-8-inducing activity in lymphocytes, suggesting that FcgammaRIII-bearing lymphocytes were responsible. Supernatants from lymphocytes incubated on immobilized IgG contained 2.2 +/- 0.8 ng/ml of IL-1beta, while enriched monocyte preparations from the same donors incubated on immobilized IgG released only 0.1 +/- 0.04 ng/ml of IL-1beta (p = 0.05). Consistent with the identification of IL-1beta as the lymphocyte factor, fibroblast or mesangial cell IL-8 release induced by the IgG-stimulated lymphocyte supernatants was inhibited by 1) the combination of IL-1R antagonist and soluble type II IL-1R, 2) an IL-1-converting enzyme inhibitor, or 3) anti-IL-1beta but not preimmune Abs. These data suggest that targeted deposits of IgG can stimulate FcgammaRIII-bearing lymphocytes to produce IL-1beta, which induces parenchymal cell IL-8 release.

Cells, Cultured↗
PubMed1998

Chemotactic factors and renal inflammation.

The mechanisms of leukocyte entry into the kidney during inflammatory renal disease have recently received considerable attention. Chemotactic factors appear to play a central role in this process, not only by inducing leukocyte movement but also by enhancing endothelial and leukocyte adhesiveness and endothelial permeability. The evidence supporting the role of chemotactic factors in renal inflammation comes from three types of studies. (1) Cell culture studies have shown that renal parenchymal cells produce chemotactic factors in response to proinflammatory stimuli. (2) Immunohistochemical and in situ hybridization analyses of renal tissue from patients or experimental animals have demonstrated local renal expression of chemotactic factors in association with inflammatory disease. (3) Experiments designed to neutralize the chemoattractant activity of specific chemotactic factors in leukocyte-dependent models of renal injury have shown an attenuation of inflammatory infiltrates and a decrease in indices of renal damage. In this article, these data are reviewed for complement-derived chemotactic factors, the leukocyte-specific chemokines, and the interstitial chemoattractant osteopontin, and the possibilities of therapeutic interventions based on abrogating chemoattractant expression or function in human renal disease are considered.

Animals↗
PubMed1997

Interleukin-1beta induction of mitogen-activated protein kinases in human mesangial cells. Role of oxidation.

Interleukin-1beta (IL-1beta) significantly influences renal cellular function through the induction of several gene products. The molecular mechanisms involved in gene regulation by IL-1beta are poorly understood; however, the appearance of novel tyrosine phosphoproteins in IL-1beta-treated cells suggests that IL-1beta may function through tyrosine phosphoprotein intermediates. The mitogen-activated protein (MAP) kinases are tyrosine phosphoproteins that could potentially mediate the effects of IL-1beta. Protein tyrosine phosphorylation following IL-1beta treatment may be dependent on redox changes since the IL-1beta receptor is not a protein-tyrosine kinase and oxidation has been shown to induce tyrosine phosphorylation. In this report we demonstrate that conditioning human glomerular mesangial cells with IL-1beta results in the tyrosine phosphorylation and activation of two members of the MAP kinase family, extracellular signal-regulated protein kinase 2 (ERK2) and p54 Jun-NH2-terminal kinase (JNK). This effect of IL-1beta is abrogated by pretreating cells with the antioxidants N-acetyl-L-cysteine or dithiothreitol. Furthermore, the effects of IL-1beta on ERK and JNK activation are reproduced by treating mesangial cells with membrane-permeable oxidants. IL-1beta and oxidants also cause phosphorylation and activation of the upstream ERK regulatory element MAP kinase kinase. Interestingly, IL-1beta, but not exogenous oxidants, causes phosphorylation of the upstream JNK activator, JNK kinase. These data indicate that IL-1beta activates ERK2 through an oxidation-dependent pathway. Exogenous oxidants and IL-1beta activate JNK through different upstream mechanisms; however, antioxidant inhibition of JNK activation indicates that endogenous oxidants may play a role in IL-1beta-induced JNK activation. Thus IL-1beta may affect mesangial cell function by activating MAP kinases, which can then regulate gene transcription. Furthermore, reactive oxygen species released during inflammatory glomerular injury may also affect mesangial function through a MAP kinase signal.

Acetylcysteine↗
PubMed1997

Fc(gamma) receptor cross-linking induces peripheral blood mononuclear cell monocyte chemoattractant protein-1 expression: role of lymphocyte Fc(gamma)RIII.

Immune complexes activate cells by cross-linking leukocyte surface Fc(gamma)Rs. Diseases associated with immune complex deposition, such as rheumatoid arthritis, glomerulonephritis, or idiopathic pulmonary fibrosis, are characterized by compartmentalized monocyte infiltration. The factors that recruit monocytes to these compartments are not well characterized; however, monocyte chemoattractant protein-1 (MCP-1) has been found in areas of tissue injury. To account for these observations we hypothesized that PBMC Fc(gamma)R cross-linking may induce MCP-1 synthesis, which stimulates further monocyte recruitment. To test this hypothesis, PBMC were incubated on increasing concentrations of immobilized human IgG, a stimulus for Fc(gamma)R cross-linking. Immunoreactive MCP-1 was produced in a dose-dependent manner (p < 0.0001). MCP-1 was specifically induced by Fc(gamma)R cross-linking, since immobilized F(ab')2 fragments of human IgG did not activate MCP-1 production. This effect was reproduced by directly cross-linking PBMC Fc(gamma)RIII, but not by cross-linking Fc(gamma)RI or Fc(gamma)RII. PBMC-derived MCP-1 stimulated monocyte chemotaxis that was inhibited by a neutralizing anti-MCP-1 Ab. MCP-1 levels correlated with increased PBMC mRNA expression. Interestingly, Fc(gamma)R cross-linking with either immobilized IgG or anti-Fc(gamma)RIII induced more MCP-1 release from PBMC than from autologous monocytes (p = 0.02). Lymphocytes, the main cell type found in PBMC preparations, did not independently produce a significant amount of MCP-1, but when incubated on immobilized IgG or anti-Fc(gamma)RIII secreted a soluble factor(s) that induced monocyte MCP-1 production. These data suggest that cross-linking PBMC Fc(gamma)R induces the production of bioactive MCP-1. This occurs in part at the level of gene transcription and involves a cooperative interaction between monocytes and lymphocytes.

Cells, Cultured↗
PubMed1997

Modulation of IL-1-induced chemokine expression in human mesangial cells through alterations in redox status.

The effects of altering intracellular redox potential on interleukin 1 (IL-1)-induced MCP-1 gene expression by human mesangial cells were examined. Thiol containing antioxidants significantly increased cellular glutathione content while decreasing glutathione disulfide levels. These antioxidants inhibited IL-1 induction of MCP-1 mRNA expression. This correlated with a decrease in DNA binding activity of NF-kappa B, a transcription factor thought to be necessary for MCP-1 gene expression. Incubation of mesangial cells with the oxidizing agents diamide or hydrogen peroxide did not upregulate MCP-1 gene expression, and prevented IL-1 induction of MCP-1 mRNA. Oxidants appeared to inhibit the degradation of I kappa B, and the translocation of NF-kappa B to the nucleus. Non-oxidative depletion of intracellular glutathione also attenuated the effects of IL-1 on MCP-1 expression. These data indicate that the intracellular redox potential is a critical determinant of cell activation by IL-1. The observation that both oxidizing and reducing environments are inhibitory suggests that redox changes can affect the IL-1 signal transduction pathway at multiple points.

Antioxidants↗
PubMed1996

Monocyte chemoattractant protein-1 levels in patients with glomerular disease.

Chemokines such as monocyte chemoattractant protein-1 (MCP-1) and interleukin-8 have been implicated in recruiting leukocytes to the glomerulus during immune renal injury. To detect the expression of MCP-1 in human glomerular disease, we measured urinary MCP-1 levels in patients with a variety of glomerulopathies. These data demonstrated that MCP-1 was present in the urine of patients with glomerular disease and that patients with inflammatory glomerulopathies had higher levels of urinary MCP-1. Urinary MCP-1 correlated with the extent of proteinuria (r = 0.71, P < 0.0001), but not with serum MCP-1 levels (r = 0.14, P > 0.3). The MCP-1 present in urine was biologically active, increasing monocyte migration in a microchemotaxis assay. This activity was attenuated by the addition of anti-MCP-1 antibody to the samples. Enumerating glomerular macrophages demonstrated that glomerular inflammation was correlated with urinary MCP-1 levels (r = 0.53, P < 0.02). Individuals with light microscopic evidence of severe glomerular injury (ie, crescents, necrosis, endocapillary proliferation) had significantly higher levels of MCP-1 in their urine than patients with less severe glomerular changes (1,962 +/- 612 pg MCP-1/mg creatinine v 314 +/- 45 pg MCP-1/mg creatinine; P < 0.002). Taken together, these results suggest that urinary MCP-1 reflects the extent to which MCP-1 that is produced in the glomerulus participates in the glomerular inflammatory response.

Chemokine CCL2↗
PubMed1995

Activation of nuclear factor-kappa B correlates with MCP-1 expression by human mesangial cells.

Emerging evidence suggests that mesangial cell-derived monocyte chemoattractant protein-1 (MCP-1) is a potentially important mediator of glomerular monocyte infiltration. Interleukin-1 beta (IL-1) has been found in glomeruli during inflammation, and is a potent inducer of MCP-1 expression by mesangial cells. Analysis of the promoter region of the human MCP-1 gene demonstrates several putative binding sites for transcription activating factors, including recognition elements for the IL-1-inducible transcription factor, nuclear factor-kappa B (NF-kappa B). This study investigated the role of NF-kappa B in IL-1-induced MCP-1 expression by human mesangial cells. We found that treating mesangial cells with IL-1 resulted in the rapid activation (within 30 min) and nuclear translocation of NF-kappa B. NF-kappa B activation could be blocked by preventing the proteolytic degradation of I kappa B, the cytoplasmic inhibitor of NF-kappa B, with the protease inhibitor tosyl-phe-chloromethylketone (TPCK). Inhibition of NF-kappa B with TPCK correlated with a dose-dependent reduction in IL-1-induced MCP-1 mRNA levels. Conversely, raising intracellular cyclic-AMP levels, or exposing mesangial cells to herbimycin A, treatments that block IL-1-induced MCP-1 mRNA expression, significantly attenuated NF-kappa B activation. Finally, blocking the synthesis of one of the protein subunits of NF-kappa B with an antisense oligonucleotide decreased MCP-1 mRNA levels in response to IL-1. These data suggest that MCP-1 gene transcription may be mediated, in part, by the transcription factor NF-kappa B.

Antioxidants↗