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Biomedical subjects

E G Neilson

Publications and source records attributed to E G Neilson.

At least 73 records · Page 4Linked to original sources
PubMed1994

The role of lymphocytes in the progression of interstitial disease.

Chronic interstitial disease is a major cause of end-stage renal failure. The process is characterized mainly by tubular atrophy and interstitial fibrosis and may be the result of primary or secondary interstitial nephritis. The secondary form attends almost all instances of progressive glomerular and vascular diseases, determining in a large part their outcome. Both forms of interstitial nephritis are initially characterized by the presence of mononuclear infiltrates with the majority being T lymphocytes. The predominance of CD4+ or CD8+ T-cells depends on the underlying cause. Both cell types may lead directly or indirectly to the induction of tubulointerstitial fibrosis. Direct stimulation of fibroblasts to proliferate and produce extracellular matrix may be caused by TGF-beta, IL-4, TNF-alpha, and other fibroblast stimulating factors. Indirect induction of fibroblasts is mediated by stimulation of monocytes/macrophages through IL-2 and IFN-gamma. Furthermore, T cells may directly interact with epithelial cells, leading, for example, to a decrease in type IV collagen production in these cells, thus contributing directly to tubular atrophy. The role of MHC class II expression on tubular epithelial cells in the process of chronic interstitial disease remains to be fully elucidated.

Animals↗
PubMed1993

Specificity of Goodpasture autoantibodies for the recombinant noncollagenous domains of human type IV collagen.

Type IV collagen has recently emerged as a family composed of five known chains (alpha 1-alpha 5), each of which contains a carboxyl-terminal noncollagenous domain (NC1) of approximately 230 amino acids. The NC1 domain of the alpha 3(IV) chain is the probable target for autoantibodies in patients with Goodpasture syndrome (GP), as evidenced from studies employing bovine type IV collagen. In the present experiments, the specificity of GP antibodies for the five NC1 domains of human type IV collagen was determined by using recombinant NC1 domains as the antigen. cDNAs encoding each NC1 domain were expressed in E. coli as fusion proteins with a 6-histidine amino-terminal leader. The recombinant NC1 monomers r alpha 1(IV), r alpha 2(IV), r alpha 3(IV), r alpha 4(IV), and r alpha 5(IV) were purified by affinity chromatography to the fusion protein using a nickel resin column, and then characterized by electrophoresis and immunoblot analysis using chain-specific peptide antibodies. The specificity of GP antibodies from four patients to these recombinant proteins was then further evaluated by immunoblot analysis and enzyme-linked immunosorbent assay measurements. The GP antibodies reacted strongly with the r alpha 3(IV) NC1 domain but were not reactive when tested against the other four recombinant monomers. In contrast, neither antisera from patients with two other forms of autoimmune disease (anti-tubular basement membrane disease and Wegener's syndrome) nor normal control sera bound to any of the recombinant NC1 moieties. These results unambiguously establish that GP antibodies are specifically targeted to the NC1 domain of the alpha 3(IV) chain of human type IV collagen. The findings also establish a methodology for large scale preparation of r alpha 3(IV) NC1 domain for use in diagnostic tests and development of therapeutic procedures and offer a strategy for the elucidation of a more complete GP epitope by site-directed mutagenesis.

Amino Acid Sequence↗
PubMed1993

Molecular structure of a cross-reactive idiotype on autoantibodies recognizing parenchymal self.

The autoimmune B cell repertoire in anti-tubular basement membrane (alpha TBM) disease is focused on the nephritogenic P1 domain of the 3M-1 target Ag in kidney and normally expresses a disease-modifying cross-reactive Id (IdX). The molecular structure of this Id was determined from a library of rat mAb alpha TBM/alpha 3M-1 by using anchor polymerase chain reactions. Our findings provide the first alignment of V region sequences for rat IgG and reveal that specificity for the P1 domain among alpha 3M-1 antibodies is derived from several recurring germ-line VH genes which have not undergone somatic mutation. The IdX in this repertoire localizes to the H chain on Western blot, and to the CDR3 region as deduced from the cDNA encoding several informative clones. Computer modeling of the Id reveals a conformational structure largely dependent on hydroxyl groups in or near turn position 4 of the H chain CDR3 region. These findings demonstrate that regulatory elements protective of autoimmunity are not encoded in the germ line as IdX, but rather emerge from a recombinatorial diversity engaged by the recognition of parenchymal self.

Amino Acid Sequence↗
PubMed1993

Human cDNA clones transcribed from an unusually high-molecular-weight RNA encode a new collagen chain.

Human collagen (COL) cDNA clones were isolated from a library representing transcripts synthesized by an established rhabdomyosarcoma (RH) cell line. The 0.6-kb insert of the first isolate encodes a discontinuous collagenous sequence not homologous to type I-XVI COL chains. Sequencing of a second clone with a 4-kb insert revealed an open reading frame (ORF) of 2154 nucleotides. The deduced amino acid (aa) sequence begins with an 186-aa noncollagenous region containing seven cysteines (Cys). Several of the Cys and surrounding aa residues can be aligned with those in type XVI, XII and IX COL. Due to the presence of two long interruptions, the 524-aa collagenous region is separated into three subdomains that each have smaller interruptions of 1-6 aa. The protein terminates with an 8-aa noncollagenous peptide including an unusual single Cys which would be expected to form an interchain disulfide bond. Results of Northern blot hybridization suggest that the new COL chain may be uncommonly large since the clone identified a low-abundance RNA at least 12.4 kb in size. The gene coding for RH COL is located on human chromosome 6. It is now important to elucidate the role of this unusual COL in the infrastructure of extracellular matrix.

Amino Acid Sequence↗
PubMed1993

Immune modulation of biologic systems in renal somatic cells.

The various theories discussed here suggest that somatic renal cells are susceptible to biologic modulation by the immune system independent of an inflammatory effect. (1) The mode of repression of type IV collagen synthesis by novel, soluble antigen-binding proteins, the down-regulation of class II MHC expression with interruption of antigen presentation to epithelia after selective gene regulation by antibody, and the diverse interactions of antibody with renal glomerular cells producing functional disturbances in endocytosis and permselectivity; (2) modification of surface-antigen composition; (3) alteration of matrix deposition, remodeling and composition; (4) biophysical perturbation of cytoskeletal and cell membrane components; (5) and lastly, alterations in cell adhesion through cell-surface alterations, all lend testimony to the richness of the signal transduction pathways in somatic cells. Although the preceding examples represent only a small fraction of those which may take place within the glomerular and tubular microenvironments, these paradigms may nevertheless serve as new models upon which one can consider the multitude of potential communications between disparate biologic systems that connect in complex organisms.

Animals↗
PubMed1993

TNF alpha induces expression of the chemoattractant cytokine RANTES in cultured mouse mesangial cells.

We investigated the effect of several immune-relevant cytokines on expression of the chemoattractant intercrine/chemokine RANTES in a mouse mesangial cell line (MMC). Fifty ng/ml recombinant tumor necrosis factor alpha (TNF alpha) induced a marked increase in RANTES transcripts after two hours. RANTES mRNA remained elevated for 24 to 48 hours after stimulation, and could be abolished by co-incubation with 30 micrograms/ml of a neutralizing rabbit anti-TNF alpha antibody. Protein expression of RANTES, as assessed by indirect immunofluorescence and Western blotting, increased in MMCs 24 hours after TNF alpha stimulation. Interleukin-1 beta, tumor necrosis factor beta (TNF beta), and lipopolysaccharide (LPS) also increased expression of RANTES mRNA. In addition, RANTES mRNA expression was stimulated in glomeruli harvested from rats following renal in vivo perfusion with TNF alpha. Our results indicate that mesangial cells produce the small cytokine RANTES. This factor, in concert with other chemoattractants, may play a role in the glomerular recruitment of inflammatory cells like macrophages/monocytes.

Animals↗
PubMed1993

Angiotensin II as a renal growth factor.

Angiotensin II (ANG II) can have multiple effects on the kidney, including influences on the regulation of glomerular hemodynamics and tubular transport as well as consequences for the glomerular processing of macromolecules. The recognized suppressive effects of angiotensin-converting enzyme inhibitors on compensatory renal growth, even in the absence of hemodynamic effects, and the well-documented proliferative effect of ANG II on vascular smooth muscle cells have provided the background for the recent intensive interest in this peptide as a renal cytokine. Diverse cell types along the nephron express a variety of ANG II receptors. These receptors and their putative signal transduction pathways have been best characterized in mesangial and proximal tubular cells. Culture experiments provide convincing evidence that ANG II can be a phenotypic influence on these cell types. The growth responses and the associated signal transduction pathways, however, are different in mesangial and proximal tubular cells. These ANG II-mediated responses are also associated with an increase in the synthesis of distinct collagen subtypes, potentially linking the growth stimulatory effects of ANG II to the irreversible changes of glomerulosclerosis and tubulointerstitial fibrosis observed in chronic renal failure. Preventing the intrarenal actions of ANG II with angiotensin-converting enzyme inhibitors or with the new, orally active, selective ANG II receptor antagonists may provide a rational therapeutic approach to attenuate the progression of a variety of kidney diseases.

Angiotensin II↗
PubMed1993

The nephritogenic T lymphocyte response in interstitial nephritis.

The work that has gone on regarding the development of nephritogenic T cells, their interactions with somatic structures in the kidney, and the vast biology that is engaged by their appearance are all amenable to study using the modern techniques of cellular and molecular biology. The models that have been developed to date illustrate common themes. The genes that encode for the effects of nephritogenic T cells operate by using the same general parameters as would be predicted for immune responses traditionally activated within the lymphoid compartment. Their immune response genes probably encode for structural proteins, some of which have been described, like the T cell receptor, T cell differentiation markers, MHC determinants, and cell-cell adhesion molecules. Maturation of nephritogenic T cell repertoires is fine-tuned by peripheral regulatory events and the cytokine bath produced by that microenvironment. Finally, CD8+ T cells that are programmed to damage the kidney can deliver signals which provoke phenotypically distinct patterns of injury. The future of research in this area holds great promise for developing a variety of new therapeutic modalities that involve antigen-specific regulation of nephritogenic T cell responses, control of cell-specific chemoattractants, modulation of cell-cell interaction molecules, and the transcriptional attenuation of MHC class II determinants in somatic cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Tophaceous gout in young patients with systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) and gout have been associated infrequently. We describe 3 young adults with SLE who developed tophaceous gout relatively early in the course of their disease. All were underexcretors of uric acid but were studied after the development of renal disease; 2 were treated with diuretics. In 2 cases, gout became obvious while lupus was quiescent.

Adult↗
PubMed1992

Progression and remission of renal disease in the Lupus Nephritis Collaborative Study. Results of treatment with prednisone and short-term oral cyclophosphamide.

OBJECTIVE: To describe the clinical course of severe lupus nephritis and to identify the risk factors for progression to renal failure among patients treated with prednisone and short-term courses of low-dose oral cyclophosphamide. DESIGN: Ancillary analyses of data from the Lupus Nephritis Collaborative Study (LNCS). SETTING: University hospital medical centers (14). PATIENTS: The 86 patients who participated in the LNCS (mean follow-up, 136 weeks [2.6 years]) and a subgroup of 63 patients with follow-up of more than 48 weeks (mean follow-up, 160 weeks [3.1 years]). MEASUREMENTS: Initial clinical and pathologic features, response to therapy within 48 weeks, and subsequent clinical events, including development of renal failure. MAIN RESULTS: Renal failure developed in 18 patients (21%). An observed elevation in serum creatinine concentration was the only initial feature predictive of subsequent renal failure. Mean (+/- SD) initial serum creatinine levels were higher in patients who subsequently developed renal failure (244 +/- 134 mumol/L [2.76 +/- 1.52 mg/dL] compared with 163 +/- 103 mumol/L [1.85 +/- 1.17 mg/dL]; P = 0.007). The risk for renal failure was higher among patients with initial serum creatinine levels greater than 106 mumol/L (1.2 mg/dL) (29% compared with 6.5%; P = 0.014). Response to therapy (defined as resolution of initial serum creatinine elevations within 48 weeks) refined the prognosis based on initial serum creatinine determinations. The risk for subsequent renal failure was higher among patients who failed to respond to therapy within 48 weeks (30% compared with 0%; P = 0.015). By comparison, 9% of patients with normal initial serum creatinine levels progressed to renal failure after 48 weeks. CONCLUSIONS: Initial serum creatinine levels and responses to initial therapy with prednisone and short-term cyclophosphamide, as used in the LNCS, can guide further therapy. Patients with normal initial serum creatinine levels or resolution of initial serum creatinine elevations within 48 weeks have a low risk for renal failure and may not require long-term treatment with cyclophosphamide.

Administration, Oral↗
PubMed1992

Inhibition of calcium oxalate crystal growth in vitro by uropontin: another member of the aspartic acid-rich protein superfamily.

The majority of human urinary stones are primarily composed of calcium salts. Although normal urine is frequently supersaturated with respect to calcium oxalate, most humans do not form stones. Inhibitors are among the multiple factors that may influence the complex process of urinary stone formation. We have isolated an inhibitor of calcium oxalate crystal growth from human urine by monoclonal antibody immunoaffinity chromatography. The N-terminal amino acid sequence and acidic amino acid content of this aspartic acid-rich protein, uropontin, are similar to those of other pontin proteins from bone, plasma, breast milk, and cells. The inhibitory effect of uropontin on calcium oxalate crystal growth in vitro supports the concept that pontins may have a regulatory role. This function would be analogous to that of other members of the aspartic acid-rich protein superfamily, which stereospecifically regulate the mineralization fronts of calcium-containing crystals.

Amino Acid Sequence↗
PubMed1992

Biosynthetic and proliferative characteristics of tubulointerstitial fibroblasts probed with paracrine cytokines.

Fibroblasts in parenchymal organs potentially contribute extracellular matrix to local fibrogenic processes. This contribution, in some circumstances, may be initiated by cytokines disseminated from inflammatory lesions. Different populations of fibroblasts, however, might respond distinctively to this cytokine bath depending on the microenvironment in which they reside. We have begun to explore this issue using syngeneic, low-passage fibroblasts cultured in serum-free media that were derived originally from the dermis (DFBs) and from tubulointerstitium (TFBs) of the kidney. Our findings indicate that, while fibroblasts from each compartment appear similar at the ultrastructural level, there are a variety of functional differences which distinguish their proliferative response, and their collagen secretory response (types I, III, IV, and V) following challenge with various doses of immune-relevant cytokines (TGF beta, EGF, IL-1, IL-2 and gamma IFN) in culture. DFBs, for example, express more surface EGF receptors than do TFBs, and, as a consequence, exhibit a more robust proliferative response to EGF in serum-free media. Unstimulated DFBs also secrete more collagen types I and III than TFBs, while unstimulated TFBs secrete more types IV and V. The expression of these collagens in TFBs was confirmed by Northern blot hybridization. When these sets of fibroblasts were further stimulated by cytokines, some of the cytokines not only differentially effect the secretion of various species of collagens within the same group of cells, but also between cells from populations which are anatomically distinct. DFBs, furthermore, at mid-level doses of cytokine, demonstrated a general trend towards less secretion of all types of collagen (particularly for TGF beta, EGF, and IL-2), while TFBs seemed less repressive. In TFBs the cytokine-induced responses for collagen types I and III tended to be discordant, and for types I and IV EGF inhibited, while TGF beta stimulated the secretory process. These findings speak collectively for the presence of a functional heterogeneity among organ-based populations of syngeneic fibroblasts in normal tissues.

Animals↗
PubMed1992

Isolation and characterization of cDNA from renal tubular epithelium encoding murine Rantes.

We have been interested in identifying proinflammatory molecules which might play a role in attracting monocytes and T cells to the kidney. Some of the new intercrines are potential candidates. In this report we have isolated cDNA encoding murine Rantes (MuRantes) from renal tubular epithelium (MCT cells). MuRantes is a 91 amino acid member of the -C-C- or intercrine beta subgroup of the Scy superfamily. The amino acid sequence for mature MuRantes was deduced from its coding cDNA and was found to be 90% homologous to its mature human counterpart (HuRantes). MCT epithelium expresses a single mRNA transcript for MuRantes of approximately 1100 bp. The MuRantes protein could be detected in cell lysates of MCT epithelium by western blotting and in the cytoplasm of MCT cells by immunofluorescence using a polyclonal antibody generated against HuRantes fusion protein. A search protocol using MuRantes-specific primers and cDNA amplification revealed that mRNAs for MuRantes are expressed additionally in syngeneic mesangial cells (MMC cells), whole kidney, liver, and spleen, as well as in nephritogenic antigen-specific CD4+ helper and CD8+ effector T cells. cDNA amplification studies also demonstrated a significant elevation in mRNA transcripts encoding MuRantes in response to the stimulation of MCT epithelium with TNF alpha and IL-1 alpha in culture, but not with TGF beta, gamma IFN, or IL-6. Our findings indicate that proximal tubular epithelium is an authentic source of MuRantes, and that transcripts encoding MuRantes are responsive to the modulating influence of paracrine factors having a known role in the development of parenchymal injury.

Amino Acid Sequence↗
PubMed1992

Attenuated expression of epithelial cell adhesion molecules in murine polycystic kidney disease.

Polycystic kidney disease is an inherited disorder of parenchymal structure that leads to renal failure. Cysts begin as focal dilations in proximal tubules and collecting ducts, giving rise to cyst walls lined by a phenotypically disturbed epithelium that expresses dysfunctional transport and matrix proteins. We used an mRNA search protocol to probe efficiently for tissue-specific disturbances that might underlie the formation of cysts. This search assessed the relative abundance of transcripts encoding a variety of growth factors (transforming growth factor-beta 1, interleukin-6, tumor necrosis factor, and endothelin-1), structural proteins (collagen IV, nidogen, fibronectin, and laminins A and B1), and cell adhesion molecules (CAMs; E-cadherin, N-CAM, laminin receptor, and fibronectin receptor) in the cystic kidneys of cpk/cpk mice and uncovered a previously unrecognized early reduction in mRNA encoding N-CAM (54%) and E-cadherin (56%) (n = 5; P less than 0.001). Levels of transcripts for growth factors, structural proteins, and for fibronectin and laminin receptors in normal and cystic kidneys were generally similar. The reduction in transcripts for N-CAM and E-cadherin in kidneys from cystic mice was not observed in autologous liver. The immunofluorescent staining of cystic kidneys confirmed that the decrease in N-CAM and E-cadherin was generally confined to regions abundant in developing cystic epithelium. The presence of both N-CAM and E-cadherin appears to guide the sequential differentiation and polarization of normal renal epithelium, and their attenuated expression in the kidney of cpk/cpk mice may be a material factor contributing to the pathogenesis of cyst formation.

Animals↗
PubMed1992

Effects of angiotensin II on proximal tubular cells stably transfected with the c-mas oncogene.

Angiotensin II (ANG II) normally induces cellular hypertrophy in proximal tubular epithelium by engaging receptor systems that use a G-protein-signaling mechanism. The c-mas oncogene also encodes part of a superfamily of vasoactive peptide receptor-like moieties that couple to G proteins. To determine whether the stable expression of the c-mas gene might alter or modify the induction of cellular hypertrophy by ANG II in tubular epithelium, a rat c-mas cDNA was cloned into the pSV2 expression vector for use in cell transfection. Scatchard analysis of ANG II binding revealed no significant differences in ANG II receptor number or in the dissociation constant between pSV2mas-transfected or wild-type MCT cells, but rather an increase in the number of receptors not replaceable by known inhibitors. ANG II also induced proliferation in pSV2mas-transfected MCT cells that was not blocked by conventional inhibitors and increased intracellular levels of inositol trisphosphate. ANG II, furthermore, did not increase de novo protein synthesis in pSV2-transfected MCT cells and failed to lower their intracellular concentration of adenosine 3',5'-cyclic monophosphate, both expected parameters of cellular hypertrophy. Our findings demonstrate that expression of c-mas in tubular epithelium can modulate tubular cell phenotype toward proliferation rather than hypertrophy. This effect is likely mediated by a reshuffling of the heterogeneity of ANG II receptors on the cell surface, or perhaps by the emergence of a new ANG II receptor, followed by alterations in the process of signal transduction.

Angiotensin II↗