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Eric G Neilson

Publications and source records attributed to Eric G Neilson.

34 records · Page 2Linked to original sources
PubMed2004

Mutant prenyltransferase-like mitochondrial protein (PLMP) and mitochondrial abnormalities in kd/kd mice.

BACKGROUND: Mice that are homozygous for the kidney disease (kd) mutation are apparently healthy for the first 8 weeks of life, but spontaneously develop a severe form of interstitial nephritis that progresses to end-stage renal disease (ESRD) by 4 to 8 months of age. By testing for linkage to microsatellite markers, we previously localized the kd gene to a YAC/BAC contig. METHODS: The sequence of the entire critical region was examined, and candidate genes were identified. These candidate genes were sequenced in both mutant (kd/kd) mice and normal controls. The phenotype was further characterized by immunohistochemistry and electron microscopy. Transgenic mice were constructed that carried the wild-type allele of the prime candidate gene, and this transgene was transferred to a kd/kd background by breeding. RESULTS: We have obtained evidence that kd is a mutant allele of a novel gene for a prenyltransferase-like mitochondrial protein (PLMP). This gene is alternatively spliced, with the larger gene product having one domain that resembles transprenyltransferase and another that is similar to geranylgeranyl pyrophosphate synthase. The smaller gene product includes only the first domain. An antiserum to PLMP localizes to mitochondria, and ultrastructural defects are present in the mitochondria of renal tubular epithelial cells, and to a lesser extent, hepatocytes and heart cells from kd/kd mice. In a line of kd/kd mice that carried the wild-type PLMP allele as a transgene, only 1 out of 13 animals expressed the disease by 120 days of age. CONCLUSION: The kd allele codes for a novel protein that localizes to the mitochondria, and the kd/kd mouse has dysmorphic mitochondria in the renal tubular epithelial cells. This mouse is therefore a unique animal model for studying mechanisms that lead to tubulointerstitial nephritis.

Amino Acid Sequence↗
PubMed2003

The gatekeeper effect of epithelial-mesenchymal transition regulates the frequency of breast cancer metastasis.

When carcinoma cells metastasize, they change their phenotype to enhance motility. Cells making this switch selectively express S100A4, a p53-associated, calcium-binding protein known in the fibroblast literature as fibroblast-specific protein-1 (FSP1). FSP1 normally acts as a conversion signal for the local formation of tissue fibroblasts by epithelial-mesenchymal transition. We describe here a novel connection between the process of fibroblast development and the acquisition of a metastatic phenotype in genetically engineered mice with mammary carcinoma. More frequent lung metastases were observed in naïve recipients given purified populations of green fluorescent protein (GFP)(+) tumor cells harvested from PyV-mT x FSP1(+/+.GFP) F1 mice compared with GFP(-) tumor cells (P < or = 0.01), where GFP expression is under the control of the FSP1 promoter. The expression of GFP in these metastases reversibly attenuates with the establishment of secondary tumor nodules. Reduced numbers of metastases were also observed in PyV-mT x FSP1(GFP/GFP) F1 mice carrying null alleles for FSP1 (P < or = 0.04) and in PyV-mT x FSP1.Delta TK(+) F1 mice rescued with nucleoside analogues while expressing thymidine kinase under the control of the FSP1 promoter (P < or = 0.01). We propose that epithelial-mesenchymal transition associated with the expression of FSP1 in tumor cells has a functional role in determining the latency of tumor dispersion and may be a convenient therapeutic target for controlling a key initiating event in metastatic progression.

Adoptive Transfer↗
PubMed2003

New insights into mechanisms of fibrosis in immune renal injury.

. Renal fibrosis is the final common pathway for many kidney lesions that lead to chronic progressive organ failure. The tubulointerstitial space occupies up to 90% of kidney volume, indicating that pathological changes in that space can not be without functional significance. By analogy to wound healing, renal fibrogenesis can be divided arbitrarily into three phases: induction, inflammatory, and post-inflammatory phases. The latter phase is of particular importance, since its length often exceeds what would be required for healing. The induction phase is characterized by the infiltration of the tubulointerstitial space by mononuclear inflammatory cells. This influx is mediated by proinflammatory cytokines and chemokines often secreted by activated tubular epithelial cells. Subsequently, these infiltrating mononuclear cells stimulate a heterogeneous group of resident fibroblasts and tubular epithelial cells to undergo phenotypic conversion into activated fibroblasts that secrete abundant extracellular matrix. Tubular epithelial cells contribute to this process through epithelial-mesenchymal transition. During the inflammatory phase these activated fibroblasts are stimulated to produce collagenous matrix mainly by cytokines, such as TGF-beta1, EGF, ET-1, and FGF-2, which are secreted by inflammatory and injured somatic cells. Occasionally however, when inflammation subsides, the matrix synthesis in the post-inflammatory phase of renal fibrogenesis continues and may be more dependent on autocrine stimulation from resident renal cells such as remaining tubular epithelium. Eventually, the collagenous matrix of fibrogenesis destroys blood supply and the perimeter of viability for fibroblasts regresses to the point where scars become acellular.

Animals↗
PubMed2003

Selective depletion of fibroblasts preserves morphology and the functional integrity of peritoneum in transgenic mice with peritoneal fibrosing syndrome.

BACKGROUND: A peritoneal fibrosing syndrome (PFS) can progressively reduce peritoneal ultrafiltration during chronic peritoneal dialysis in patients with renal failure. The pathogenesis of PFS is unclear and the role of peritoneal fibroblasts has not been evaluated experimentally. METHODS: We followed the fate of fibroblasts producing PFS in a mouse model using fibroblast-specific protein 1 (FSP1) as a marker. PFS was induced by daily peritoneal infusions of chlorhexidine gluconate (CHG) saline into transgenic mice expressing the thymidine kinase (Delta tk) gene under the control of the FSP1 promoter (FSP1.Delta tk mice). To demonstrate the role of fibroblasts in PFS, we treated these FSP1.Delta tk mice with a nucleoside analogue to induce DNA chain termination and fibroblast death. RESULTS: Mice receiving peritoneal infusions of CHG saline every other day for 2 weeks developed increasing numbers of FSP1+ fibroblasts in the subserosal layers of the visceral peritoneum. Mac-3+ monocytes (macrophages) subsequently accumulated over the next 2 weeks in association with increased deposition of type I collagen and increased endothelial vascularity (CD31+) in these subserosal tissues. Since these peritoneal fibroblasts expressed monocyte chemoattractant protein-1 (MCP-1), heat shock protein 47 (HSP47), and vascular endothelial growth factor (VEGF), we suspect they were partially responsible for macrophage recruitment, matrix production, and the neoangiogenesis in the subserosal tissue. Treatment of PFS in FSP1.Delta tk transgenic mice with a nucleoside analogue selectively reduced the numbers of peritoneal fibroblasts and attenuated the attendant changes in peritoneal histology. Rescuing the peritoneal membrane from chronic thickening and neoangiogenesis by reducing the number of fibroblasts also preserved ultrafiltration. CONCLUSION: Peritoneal fibroblasts play a pivotal role in PFS, and their deletion using a fibroblasts-specific transgene was effective in preventing peritoneal fibrogenesis.

Animals↗
PubMed2003

Pathogenesis of Goodpasture syndrome: a molecular perspective.

Goodpasture (GP) syndrome is a form of anti-glomerular basement membrane (GBM) disease, in which autoantibodies bind to alpha3(IV) collagen in GBM causing rapidly progressive glomerulonephritis and pulmonary hemorrhage. The conformational GP epitopes have been mapped to 2 regions within the noncollagenous (NC1) domain of the alpha3(IV) chain. Recently, we described the molecular organization of the autoantigen in the native alpha3alpha4alpha5(IV) collagen network of the GBM. The crystal structure of the NC1 domain has revealed how the GP epitopes are sequestered in the native GBM. Further insight into the pathogenesis of disease has been obtained from better animal models. These advances provide a foundation for the development of new specific therapies.

Animals↗
PubMed2003

Effects of performance-based compensation and faculty track on the clinical activity, research portfolio, and teaching mission of a large academic department of medicine.

PURPOSE: Academic departments of medicine must compete effectively for extramural research support and access to patients while preserving their teaching mission. There is not much literature describing plausible mechanisms for ensuring success. The authors describe the design, implementation, and testing of a performance-based compensation plan in a department of medicine that is closely linked to the faculty appointment track. METHOD: Over a three-year period, the changes this plan effected in research portfolio, clinical enterprise, and faculty satisfaction as well as the teaching perceptions of students and housestaff were measured. RESULTS: The compound annual growth rate (CAGR) for clinical work grew 40% faster after plan implementation. Federal funding increased at a CAGR that was 170% greater than before. The department halved its award rankings at the National Institutes of Health and faculty satisfaction improved compared with the former method of compensation. Faculty who better understood the plan were more satisfied with the conversion. High measures of teaching quality were maintained by faculty with no apparent change in satisfaction among students or housestaff. CONCLUSIONS: This performance-based compensation plan with its emphasis on the objectives of career orientation and faculty track assignment strengthened the opportunity to grow both clinical productivity and the funded research portfolio.

Academic Medical Centers↗
PubMed2003

Epithelial-mesenchymal transition and its implications for fibrosis.

Epithelial to mesenchymal transition (EMT) is a central mechanism for diversifying the cells found in complex tissues. This dynamic process helps organize the formation of the body plan, and while EMT is well studied in the context of embryonic development, it also plays a role in the genesis of fibroblasts during organ fibrosis in adult tissues. Emerging evidence from studies of renal fibrosis suggests that more than a third of all disease-related fibroblasts originate from tubular epithelia at the site of injury. This review highlights recent advances in the process of EMT signaling in health and disease and how it may be attenuated or reversed by selective cytokines and growth factors.

Animals↗
PubMed2002

The role of fibroblasts in thymocyte-positive selection.

Mice with fibroblast-specific expression of TAP-1 were generated by expressing the TAP-1 transgene under the control of the fibroblast-specific protein (FSP) 1 promoter/enhancer on TAP-1-deficient background. MHC class I expression in primary fibroblast cultures isolated from the resulting strain mimicked that of wild-type counterparts. MHC class I was detected in both types of fibroblasts following treatment with IFN-alphabeta. Positive selection of CD4(-)CD8(+) thymocytes was observed in neither adult nor fetal/neonatal thymus of transgenic mice. IFN-alphabeta-induced expression of MHC class I rescued positive selection of CD4(-)CD8(+) T cells in fetal thymic organ cultures, but not in adult mice. Contrary to previous suggestions, our results indicate a limited role of fibroblasts in promoting positive selection. In addition, the results suggest that positive selection may occur by a different mechanism in fetal vs adult thymus.

ATP Binding Cassette Transporter, Subfamily B, Mem↗
PubMed2002

Differential expression of type IV collagen isoforms in rat glomerular endothelial and mesangial cells.

Type IV collagen, which is encoded by six genetically distinct alpha-chains (alpha 1-alpha 6), is a major component of the kidney glomerulus. The alpha 1(IV) and alpha 2(IV) chains are present predominantly in the mesangial matrix, whereas the alpha 3(IV), alpha 4(IV), and alpha 5(IV) chains are localized almost exclusively to the glomerular basement membrane (GBM). Thickening of the GBM and expansion of the mesangial matrix are believed to contribute to the pathogenesis of diabetic nephropathy. In the present study, we evaluated the expression of alpha 1(IV), alpha 3(IV), and alpha 5(IV) chains in rat glomerular endothelial (GEndC) and mesangial cells (GMC). Under physiological concentrations of glucose (5 mM), alpha 1(IV) and alpha 5(IV) chains were detectable in GMCs, with an obvious absence of alpha 3(IV) chain. All three isoforms tested were present in GEndCs. At diabetic concentrations of glucose (25 mM), alpha 1(IV) was up-regulated in GMCs, whereas expression level of alpha 1(IV) remained unaltered in GEndCs. The alpha 3(IV) and alpha 5(IV) chains were up-regulated in GEndCs, but remained unchanged in GMCs under diabetic glucose concentrations (25 mM). Collectively, our results demonstrate that GMC might contribute to mesangial matrix expansion, mediated by alpha 1(IV) collagen, while GEndC might contribute to thickening of GBM, mediated by alpha 3(IV) collagen, in patients with diabetic nephropathy.

Animals↗
PubMed2002

Impaired T cell function in RANTES-deficient mice.

The chemokine RANTES is a chemoattractant for monocytes and T cells and is postulated to participate in many aspects of the immune response. To evaluate the biological roles of RANTES in vivo, we generated RANTES-deficient (-/-) mice and characterized their T cell function. In cutaneous delayed-type hypersensitivity assays, a 50% reduction in ear and footpad swelling was seen in -/- mice compared to +/+ mice. In vitro, polyclonal and antigen-specific T cell proliferation was decreased. Quantitative analysis using the fluorescent dye carboxy-fluorescein succinimidyl ester revealed that this proliferative defect was due both to fewer antigen-reactive T cells and to a reduction in the capacity of these cells to proliferate. In addition, IFN-gamma and IL-2 production by the -/- T cells was dramatically decreased. Together, these data suggest that RANTES is required for normal T cell functions as well as for recruiting monocytes and T cells to sites of inflammation.

Animals↗
PubMed2002

Human antiglomerular basement membrane autoantibody disease in XenoMouse II.

BACKGROUND: Previous studies have identified regions within alpha3(IV) collagen in human antiglomerular basement membrane (anti-GBM) disease, however, information pertaining to the nature of the pathogenic human autoantibodies has been limited by a lack of a relevant disease model. Availability of engineered mice that produce antibodies (that is, XenoMouse II strains) provides an ideal opportunity to examine the human antibody response. METHODS: XenoMouse II mice that produce human IgG2 (gamma2kappa) in response to antigenic challenge were immunized with various forms of alpha3(IV)NC1 GBM collagen, including native bovine alpha3(IV) NCl collagen, E. coli expressed r alpha3(IV)NCl, and mammalian fetal kidney 293 cell expressed r alpha3(IV)NC1 preparations. The mice were evaluated for autoantibody (Ab) production and nephritis. RESULTS: All immunized XenoMouse II animals produced human anti-GBM Ab associated with proliferative glomerulonephritis, linear IgG deposits along the murine GBM and tubular basement membrane (TBM), C3 deposits (weaker). A fully human mAb (Ig gamma2kappa), produced from a mouse immunized with native bovine alpha3(IV)NCl collagen produced basement membrane deposits, nephritis and proteinuria on transfer to normal XenoMouse II. Furthermore, monoclonal antibodies (mAb) shared idiotypic properties with polyclonal autoantibodies derived from patients with anti-GBM disease, supporting a structural relationship among the antibodies. CONCLUSIONS: The results further support the importance of alpha3(IV)NCl collagen in the pathogenesis of anti-GBM disease. Moreover, to our knowledge this is the first demonstration that experimentally induced, pathogenic human autoantibodies result in disease. This new model of anti-GBM disease, therefore, provides the means and unique reagents to both decipher the molecular basis of the human anti-GBM autoantibody response and the opportunity to test specific therapies aimed at modulation of either B cells producing human autoantibodies or the human pathogenic antibodies themselves, in vivo, prior to trial in patients with the spontaneous form of the disease.

Animals↗
PubMed2002

Role of basic fibroblast growth factor-2 in epithelial-mesenchymal transformation.

BACKGROUND: Epithelial-mesenchymal transformation (EMT) plays an important role in embryonic development and tumorigenesis and has been described in organ remodeling during fibrogenesis. In the kidney, EMT can be induced efficiently in cultured proximal tubular epithelium by coincubation of transforming growth factor (TGF)-beta1 and epidermal growth factor (EGF). Recently, we also have observed overexpression of basic fibroblast growth factor-2 (FGF-2) protein and mRNA in human kidneys with marked interstitial fibrosis. The aims of the present study were to compare the effects of FGF-2 as a facilitator of EMT in tubular epithelial cells with EGF and TGF-beta1. We analyzed the morphogenic effects of the three cytokines on four different aspects of EMT: cell motility, expression and regulation of cellular markers, synthesis and secretion of extracellular matrix (ECM) proteins as well as matrix degradation. METHODS: Cell motility was studied by a migration assay and cell differentiation markers were analyzed by immunofluorescence and immunoblots. In addition, regulation of the epithelial adhesion molecule E-cadherin and fibroblast-specific protein 1 (FSP1) were analyzed by luciferase reporter constructs and stable transfections. ELISAs for collagen types I and IV and fibronectin were used for ECM synthesis, and zymograms were utilized for analysis of matrix degradation. RESULTS: FGF-2 induced cell motility across a tubular basement membrane in two tubular cell lines. All three cytokines induced the expression of vimentin and FSP1, but only FGF-2 and TGF-beta1 reduced cytokeratin expression by immunofluorescence. These effects were most demonstrable in the distal tubular epithelial cell line and were confirmed by immunoblot analyses. Expression of E-cadherin was reduced by 61.5 +/- 3.3% and expression of cytokeratin by 91 +/- 0.5% by TGF-beta1 plus FGF-2. Conversely, the mesenchymal markers alpha-smooth muscle actin (SMA) and FSP1 were induced with FGF-2 by 2.2 +/- 0.1-fold and 6.8 +/- 0.9-fold, respectively. Interestingly, de novo expression of the mesenchymal marker OB-cadherin was induced only by FGF-2 and EGF but not by TGF-beta1. All three cytokines stimulated FSP1 and decreased E-cadherin promoter activity. FGF-2 also induced intracellular fibronectin synthesis but not secretion, the latter of which was stimulated exclusively by TGF-beta1. Finally, zymographic analyses demonstrated that FGF-2 induced MMP-2 activity by 2.6 +/- 0.5-fold and MMP-9 activity by 2.4 +/- 0.1-fold, providing a mechanism for basement membrane disintegration and migratory access of transforming epithelium to the interstitium. CONCLUSIONS: FGF-2 makes an important contribution to the mechanisms of EMT by stimulating microenvironmental proteases essential for disaggregation of organ-based epithelial units. Furthermore, the expression of epithelial and mesenchymal marker proteins seems to be affected at the promoter level.

Animals↗
PubMed2002

Evidence that fibroblasts derive from epithelium during tissue fibrosis.

Interstitial fibroblasts are principal effector cells of organ fibrosis in kidneys, lungs, and liver. While some view fibroblasts in adult tissues as nothing more than primitive mesenchymal cells surviving embryologic development, they differ from mesenchymal cells in their unique expression of fibroblast-specific protein-1 (FSP1). This difference raises questions about their origin. Using bone marrow chimeras and transgenic reporter mice, we show here that interstitial kidney fibroblasts derive from two sources. A small number of FSP1(+), CD34(-) fibroblasts migrate to normal interstitial spaces from bone marrow. More surprisingly, however, FSP1(+) fibroblasts also arise in large numbers by local epithelial-mesenchymal transition (EMT) during renal fibrogenesis. Both populations of fibroblasts express collagen type I and expand by cell division during tissue fibrosis. Our findings suggest that a substantial number of organ fibroblasts appear through a novel reversal in the direction of epithelial cell fate. As a general mechanism, this change in fate highlights the potential plasticity of differentiated cells in adult tissues under pathologic conditions.

Animals↗