Vimentin expression does not assist in predicting survival in ductal carcinoma of the breast

AIMS

To establish the value of vimentin expression in predicting survival in patients with breast cancer.

METHODS

Five-year follow-up data were obtained for 68 patients with ductal carcinoma (NOS) of the breast in whom vimentin expression had been studied in fresh frozen and formalin-fixed, paraffin-embedded tissue. The predictive value on survival of tumour size, growth fraction (as assessed using the Ki67 monoclonal antibody), oestrogen receptor status and Bloom and Richardson grade of the primary tumour, and the presence or absence of lymph node metastases in axillary samples, were also studied.

RESULTS

Twenty-two patients died of their disease within 5 years of diagnosis. Vimentin expression either on frozen or paraffin sections did not provide a statistically significant prediction of survival. On univariate analysis tumour grade, size and the presence of lymph node metastases provided prognostic information. Only lymph node status was of independent prognostic importance on multivariate analysis.

CONCLUSIONS

Whilst these results confirm the value of established prognostic factors, they do not support the use of vimentin expression in either fresh or fixed tissue for the prediction of survival in ductal carcinoma (NOS) of the breast.

Prognostic factors of gastrointestinal stromal tumors

Gastrointestinal stromal tumors (GIST) are rare neoplasms of unknown etiology and pathogenesis. Their clinical behavior is very unpredictable and a reliable prognostic factor is lacking. The aim of this study was to analyze some prognostic factors and estimate which one is the most reliable. Thirty-eight biopsy specimens of GIST were immunolabeled for PCNA, CD34, vimentin, NSE and actin. The greatest diameter, histological grading, mitotic count, DNA-index and S-phase were estimated for each case. All patients were followed-up for at least 24 months or to death. The data were analysed by univariate and multivariate statistical analysis using a computer program. The results showed that greatest diameter, tumor grade, mitotic count and PCNA-index are prognostic factors in univariate analysis. In multivariate analysis only the greatest diameter is a useful prognostic factor for planning further therapy.

Role of heat shock protein 47 on tubulointerstitium in experimental radiation nephropathy

The molecular mechanisms of fibrosis in radiation nephropathy have received scant attention. Heat shock protein 47 (HSP47), a collagen-binding stress protein, helps in the intracellular processing of procollagen molecules during collagen synthesis. We investigated the role of HSP47 in the progression of radiation nephropathy using experimental radiation nephropathy. Experimental rat groups were as follows: (i) group I, sham operated (n = 12); (ii) group II, single doses of irradiation, either 7, 15 or 25 Gy to left kidney (n = 60); and (iii) group III, a similar irradiation procedure as group II after right nephrectomy (n = 60). The rats were followed up until 9 months after renal exposure to radiation. Renal dysfunction (as determined by serum creatinine and blood urea nitrogen) and hypertension were noted in group III rats, along with inflammatory cell infiltration and interstitial fibrosis (as determined by increased deposition of collagens). Compared to control rat kidneys, an increased expression of HSP47 was noted in kidneys obtained from irradiated rats. By double immunostaining, HSP47-expressing cells were identified as alpha-smooth muscle actin-positive myofibroblasts and vimentin-positive tubular epithelial cells. Increased expression of HSP47 was closely associated with increased deposition of collagens in the widened interstitium of irradiated rats. Overexpression of HSP47 by phenotypically altered tubulointerstitial cells might play a role in excessive assembly/synthesis of collagens and could contribute to tubulointerstitial fibrosis in radiation nephropathy.

Evolution of cell phenotype and extracellular matrix in tissue-engineered heart valves during in-vitro maturation and in-vivo remodeling

BACKGROUND AND AIM OF THE STUDY

Contemporary tissue valves are non-viable, and unable to grow, repair or remodel. It was postulated that tissue-engineered heart valves (TEHV) fabricated from autologous cells and a biodegradable scaffold could yield a dynamic progression of cell phenotype and extracellular matrix (ECM), in vitro and in vivo, and ultimately recapitulate native valve microscopic architecture.

METHODS

Trileaflet valve constructs were fabricated from poly-4-hydroxybutyrate-coated polyglycolic acid seeded with ovine endothelial and carotid artery medial cells, cultured in vitro for 4-14 days in a pulse duplicator, implanted as pulmonary valves in five lambs, and explanted at 4-20 weeks. ECM composition and collagen architecture were examined by histology (including Movat pentachrome stain and picrosirius red under polarized light), and cell phenotype by immunohistochemistry.

RESULTS

Cells from in-vitro constructs (14 days) were activated myofibroblasts, with strong expression of alpha-actin (microfilaments), vimentin (intermediate filaments) and SMemb (non-muscle myosin produced by activated mesenchymal cells). Cells from in-vivo explants at 16-20 weeks were fibroblast-like, with predominant vimentin expression and undetectable levels of alpha-actin (similar to native valve). Collagen elaboration and cellular expression of MMP-13 (collagenase 3) were evident in vitro at 14 days. In-vivo explants had increased collagen accumulation and strong MMP-13 expression at 4-8 weeks, but less activation (decreased expression of SMemb) and patchy endothelial cells at 16-20 weeks. Moreover, the ECM architecture of 16- to 20-week explanted TEHV resembled that of native valves.

CONCLUSION

Cell phenotype and ECM in TEHV prepared in vitro and implanted in vivo are dynamic, and reflect the ability of a vital tissue to remodel and, potentially, to grow.

The expression of vimentin in HL-60 cells induced with etoposide using immunofluorescence and immunogold methods

HL-60 leukemic cells were treated with 6 different doses of etoposide for 72 hours. Changes in the distribution of vimentin were found to be dependent on the concentration of etoposide. As compared with control cells there were distinct changes in cells incubated with 100 and 200 microM/L of the drug. The size of cells treated with 100 microM/L and especially with 200 microM/L increased, but the number of cells decreased. In control cells and those treated with 0.02, 0.2 and 2 microM/L etoposide, vimentin was seen rather as a ring often with the increased concentration near one pole of the cells. Cells at 20 microM/L etoposide showed the same staining pattern but more brighter cells were found. The addition of 100 microM/L and 200 microM/L etoposide to cells resulted in diffusely distributed fluorescence staining, which often appeared as a quite dense network around the nucleus. Immunogold labelling was observed in cells treated with all doses of etoposide and control cells. Labelling was localized in the nucleus but also in the cytoplasm but rather in the area of the nucleus.

Up-regulation of vimentin expression during regeneration in the adult fish brain

In contrast to mammals, the brains of teleost fish exhibit an enormous regenerative capacity following injury. Here, we have examined the potential role of vimentin in this wound healing. Fifteen days after application of a mechanical lesion to the corpus cerebelli in the teleost fish Apteronotus leptoryhnchus, the areal density of vimentin-positive fibres increased significantly at the lesion site and in the remaining ipsilateral molecular layer. This density remained elevated throughout the time period of up to 100 days examined. Based on this spatio-temporal pattern of vimentin up-regulation we propose that this intermediate filament protein is involved in the survival, differentiation, and/or dendritic growth of the new cells that replace damaged cells in the injury zone.

Expression of extracellular matrix proteins and vimentin in testes of azoospermic man: an immunohistochemical and morphometric study

AIM

To investigate the changes in the extracellular matrix protein expression and the morphology of seminiferous tubules in the testis of 88 azoospermic men.

METHODS

The patients were of the following categories: (1) 22 cases of Sertoli-cell-only syndrome, (2) 20 cases of spermatogenic arrest, and (3) 46 cases with hypospermatogenesis. Testicular sections were immunohistochemically stained for fibronectin, vimentin, laminin and collagen type IV. The seminiferous tubular diameter and the connective matrix zone (CMZ, the acellular zone between the basement membrane [BM] and the peritubular cells) thickness were measured. Seminiferous tubules were typed according to the thickness of the connective matrix in the lamina propria. The predominant tubule type and the Johnsen and Silber scores were determined.

RESULTS

The mean tubular diameter were 119 +/- 27, 117 +/- 20, and 140 +/- 38 microm for Groups 1, 2, and 3, respectively. Both the laminin and the type IV collagen were localized to the epithelial BM and peritubular cells. In most of the tubules, BM and peritubular cells were separated by a homogenous acellular layer, the CMZ, in which laminin, type IV collagen, fibronectin and vimentin were not present. It is perceived that the worse the testicular histology, the higher the thickness of the CMZ.

CONCLUSION

In testis with no or low sperm production, the diameter of the seminiferous tubules is decreased, the thickness of the seminiferous tubular wall is increased and a CMZ is formed between the peritubular cells and the BM. The thickness of CMZ is increasing with the advancement of testiclar deterioration. The most important morphologic predictive factor for spermiogenesis is the predominant

Adenomatoid tumors of the uterus: an analysis of 60 cases

Sixty cases of uterine adenomatoid tumors (ATs) are reported. All except four were incidental findings in hysterectomy specimens, three of these being discovered preoperatively as large multicystic tumors. ATs were classified into two distinctive macroscopic patterns: small, solid tumors and large, cystic ones. The 56 small, solid ATs ranged from 0.2 to 3.5 cm, (average 2.1 cm); 48 were nodular and 8 diffuse. The four large, cystic tumors ranged from 7 to 10 cm. Inflammation occurred in 65% of the tumors, and a smooth muscle reaction, identified by an increased Ki-67 index, was present in most cases. Both types were histologically similar except for the presence of short papillae in cystic tumors, which also showed serosal involvement. Both were immunoreactive for cytokeratins, calretinin, HMBE-1, and vimentin. Estrogen and progesterone nuclear receptors and EMA were negative. These tumors represent a spectrum ranging from small and solid to large and cystic ATs in the female genital tract, whereas outside the genital tract they are morphologically similar to multicystic mesothelioma. Although a reactive origin for ATs often seems plausible, especially when inflammation is present, their neoplastic nature should not be ignored.

Distinction between endometrial and endocervical adenocarcinoma: an immunohistochemical study

We investigated the possibility of distinguishing between primary endometrial and endocervical adenocarcinomas by using a panel of immunohistochemical stains, which included vimentin (VIM), carcinoembryonic antigen (CEA), epithelial membrane antigen (EMA), and cytokeratins 7 and 20 (CK7 and CK20). Twenty-nine endocervical adenocarcinomas (CCAs) and 30 endometrial adenocarcinomas (EMCAs) including cases with overlapping histologic features (CCAs with endometrioid differentiation [15/29] and EMCAs with mucinous differentiation [16/30]) were evaluated. Most EMCAs (29/30, 97%) were VIM positive, whereas only 2/29 (7%) CCAs were VIM positive. The great majority of EMCAs (28/30) and all 29 CCAs were CK7 positive, whereas all 30 EMCAs and 27/29 CCAs were negative for CK20. CEA positivity was more common in CCAs (18/29, 62%) than in EMCAs (8/30, 27%). EMA positivity was present in all 30 EMCAs and in 26 of 29 (90%) CCAs. We conclude that VIM and CEA are useful immunohistochemical markers in distinguishing EMCAs and CCAs, but CK7, CK20, and EMA are not useful in this distinction.

A panel of immunohistochemical stains, including carcinoembryonic antigen, vimentin, and estrogen receptor, aids the distinction between primary endometrial and endocervical adenocarcinomas

The histological distinction between a primary endometrial and a primary endocervical adenocarcinoma is often difficult, especially in small biopsy specimens. A preoperative distinction is important because primary surgical management differs between the two tumors. Cases of primary endometrioid endometrial (n=30) and primary endocervical (n=26) adenocarcinoma of endocervical type were stained immunohistochemically with the monoclonal antibodies against carcinoembryonic antigen (CEA), vimentin, estrogen receptor (ER), and 34 beta E12. In all cases the origin of the adenocarcinoma was confirmed by examination of the definitive pathology specimen. There was diffuse positive nuclear staining for ER in 28 of 30 (93%) endometrial adenocarcinomas. ER was negative in 16 of 26 endocervical adenocarcinomas, and there was focal weak nuclear staining in the other cases. Vimentin was positive in 29 of 30 (97%) endometrial adenocarcinomas but in only 2 of 26 (8%) endocervical adenocarcinomas. CEA was positive in 25 of 26 (96%) endocervical adenocarcinomas, mostly with diffuse membranous and cytoplasmic staining. Positivity with CEA was present in 21 of 30 (70%) endometrial adenocarcinomas but was largely confined to squamoid areas with only 12 tumors exhibiting focal membranous staining of the glandular component. 34 beta E12 was diffusely positive in all except one cervical adenocarcinoma. In endometrial carcinomas, positivity was strongest in squamoid areas but there was positive staining, either focally or diffusely, of the glandular component in 27 cases. In summary, primary endometrioid endometrial adenocarcinomas are characterized by diffuse, strong, positive staining for vimentin and ER and negative or very focal, positive staining of the glandular component for CEA. In contrast, primary endocervical adenocarcinomas are characterized by CEA positivity, which is usually but not always diffuse, negativity for vimentin, and negativity or focal weak positivity for ER. 34 beta E12 is of no value in the distinction between endometrial and endocervical adenocarcinomas. A panel of immunohistochemical stains, comprising CEA, vimentin, and ER, generally allows confident preoperative distinction between a primary endometrial and endocervical adenocarcinoma.

Cyclooxygenase-2 in myocardium stimulation by angiotensin-II in cultured cardiac fibroblasts and role at acute myocardial infarction

Myocardial infarction is followed by a complex repair process that includes a significant role for inflammatory cells. Cyclooxygenase-2 (COX-2) plays a key role in mediating inflammation. Contribution of COX-2 to inflammatory response following myocardial infarction is less certain. In an effort to evaluate the function of COX-2 and prostaglandin E(2)(PGE(2)) in myocardial infarction, we examined the role of COX-2 after angiotensin II (Ang II) stimulation in cardiac fibroblasts and in rats with experimental myocardial infarction (MI). We combined Western blot analysis and enzyme immunoassay to demonstrate COX-2 expression and PGE(2)release in cardiac fibroblasts. Isolated cardiac fibroblasts were stimulated with Ang II. Unstimulated fibroblasts showed no COX-2 protein expression. Fibroblasts stimulated with Ang II showed a strong time-dependent expression of COX-2 protein. The p38 mitogen-activated protein kinase (MAPK) inhibitor SB203580 but not the p42/44 MAPK-inhibitor PD98059 suppressed Ang II-induced COX-2 protein expression. COX-2 expression correlated with a significantly increased PGE(2)release from cardiac fibroblasts. The COX-2 specific inhibitor NS-398 suppressed the Ang II-stimulated PGE(2)production. We then investigated COX-2 expression and inflammatory cell infiltration in our rat model of myocardial infarction. MI was produced by coronary artery ligation in adult female Wistar rats. The period of coronary artery occlusion was 96 h. The selective COX-2 inhibitor rofecoxib (3 mg/kg/d), administered orally, was given one day before MI and continued for four days. Western blotting showed expression of COX-2 protein in the area of necrosis and the infarct border zone. Immunofluorescence analysis showed macrophage infiltration as well as fibroblast proliferation in the infarct border zone of 4-d infarcted tissue and a significantly reduced cell invasion and fibroblast proliferation in infarcted tissue of rats treated with rofecoxib. MI size at day 4 was comparable in untreated and treated rats. In conclusion, we demonstrate that pharmacological interference with prostaglandin synthesis in myocardial infarction is associated with reduced myocardial invasion of inflammatory cells.

Ovarian teratomas with florid benign vascular proliferation: a distinctive finding associated with the neural component of teratomas that may be confused with a vascular neoplasm

Prominent benign vascular proliferations associated with neural tissue in five cases of ovarian teratoma are described. The ages of the patients ranged from 15 to 35 years. Three of the five had tumors confined to the ovary, one had peritoneal implants, and one had widespread metastatic immature teratoma. Two of the patients are alive and well, 8 and 9 years postoperatively. Follow-up is unavailable in two cases and the final case was recent. The tumor in three of the cases had features of mature cystic teratoma including abundant mature neural tissue and, in one instance, microscopic foci of primitive neuroepithelium. The tumor in the fourth case was an immature teratoma with abundant primitive neuroepithelium, and in the fifth case was a mixed germ cell tumor, composed mostly of immature teratoma with a minor component of yolk sac tumor. In all the tumors there was a prominent vascular proliferation composed of long thin-walled, curved vessels or a solid glomeruloid arrangement. Immunohistochemistry done in two cases confirmed the vascular nature of the proliferation. Angiogenesis, likely as an expression of vascular endothelial growth factors, is a well-known phenomenon in a variety of neural and neuroendocrine neoplasms, in particular high-grade gliomas. However, very few cases of this phenomenon have been described in association with neural tissue in the ovary. Recognition of this proliferation as a benign secondary one is important to avoid misdiagnosis of a vascular neoplasm or an immature teratoma, as happened in one of our cases.

Gene induction and categorical reprogramming during in vitro human endometrial fibroblast decidualization

Gene induction and categorical reprogramming during in vitro human endometrial fibroblast decidualization. Physiol Genomics 7: 135-148, 2001. First published September 21, 2001; 10.1152/physiolgenomics.00061.2001.-Human decidual fibroblasts undergo a differentiative commitment to the acquisition of endocrine, metabolic, and structural cell functions in a process known as decidualization. Decidualization is critical for embryo implantation and placental function. We characterized gene expression pattern kinetics during decidual fibroblast differentiation by microarray analysis. Of 6,918 genes analyzed, 121 genes were induced by more than twofold, 110 were downregulated, and 50 showed biphasic behavior. Dynamically regulated genes were could be fit into nine K-means algorithm-based kinetic pattern groups, and by biologic classification, into five categories: cell and tissue function, cell and tissue structure, regulation of gene expression, expressed sequence tag (EST), and "function unknown." Reprogramming of genes within specific functional groups and gene families was a prominent feature that consisted of simultaneous induction and downregulation of a set of genes with related function. We previously observed a conceptually similar process during fetal trophoblast differentiation, in which the same phenomena applied to different genes. Of the 569 dynamically regulated genes regulated by either model, only 81 of these were in common. These results suggest that reprogramming of gene expression within focused functional categories represents a fundamental aspect of cellular differentiation.

Immunocytochemical analysis of vimentin expression patterns in porcine embryos suggests mesodermal differentiation from day 9 after conception

The expression of the intermediate filament proteins vimentin and keratin in porcine embryos was studied by whole-mount immunocytochemistry between day 7 and day 11 after conception. Expression of vimentin was first detected in the inner cell mass of about 50% of the 9-day-old embryos. In elongated 11-day-old embryos, cells expressing vimentin were observed in the epiblast (after disappearance of Rauber's membrane) and in cells migrating from the epiblast between the trophoblast and the underlying hypoblast layer. A keratin-positive response was observed in trophectoderm cells at all stages. These findings suggest that inner cell mass cells in the pig start differentiating into mesodermal cells not later than day 9 after conception. While the delamination of the mesodermal germ layer is known to correlate with the loss of pluripotency of the inner cell mass cells, the early onset of mesodermal differentiation in the porcine embryo, characterized by vimentin expression and in contrast to the mouse, could in part be responsible for the lack of success in establishing pluripotent embryonic stem cell lines in this species. Our results suggest that further attempts to isolate inner cell mass-derived pluripotent cells should be attempted well before day 9 after conception.

A programmed ependymal denudation precedes congenital hydrocephalus in the hyh mutant mouse

Hydrocephalic hyh mice are born with moderate hydrocephalus and a normal cerebral aqueduct. At about the fifth postnatal day the aqueduct becomes obliterated and severe hydrocephalus develops. The aim of the present investigation was to investigate the mechanism of this hydrocephalus, probably starting during fetal life when the cerebral aqueduct is still patent. By use of immunocytochemistry and scanning electron microscopy, mutant (n = 54) and normal (n = 61) hyh mouse embryos were studied at various developmental stages to trace the earliest microscopic changes occurring in the brains of embryos becoming hydrocephalic. The primary defect begins at an early developmental stage (E-12) and involves cells lining the brain cavities, which detach following a well-defined temporo-spatial pattern. This ependymal denudation mostly involves the ependyma of the basal plate derivatives. There is a relationship between ependymal denudation and ependymal differentiation evaluated by the expression of vimentin and glial fibrillary acidic protein. The ependymal cells had a normal appearance before and after detachment, suggesting that their separation from the ventricular wall might be due to abnormalities in cell adhesion molecules. The process of detachment of the ventral ependyma, clearly visualized under scanning electron microscope, is almost completed before the onset of hydrocephalus. Furthermore, this ependymal denudation does not lead to aqueductal stenosis during prenatal life. Thus, the rather massive ependymal denudation appears to be the trigger of hydrocephalus in this mutant mouse, raising the question about the mechanism responsible for this hydrocephalus. It seems likely that an uncontrolled bulk flow of brain fluid through the extended areas devoid of ependyma may be responsible for the hydrocephalus developed by the hyh mutant embryos. The defect in these embryos also includes loss of the hindbrain floor plate and a delayed in the expression of Reissner fiber glycoproteins by the subcommissural organ.

Peripheral-type benzodiazepine receptor levels correlate with the ability of human breast cancer MDA-MB-231 cell line to grow in SCID mice

MDA-MB-231 (MDA-231) human breast cancer cells have a high proliferation rate, lack the estrogen receptor, express the intermediate filament vimentin, the hyaluronan receptor CD44, and are able to form tumors in nude mice. The MDA-231 cell line has been used in our laboratory to examine the role of the peripheral-type benzodiazepine receptor (PBR) in the progression of cancer. During these studies 2 populations of MDA-231 cells were subcloned based on the levels of PBR. The subclones proliferated at approximately the same rate, lacked the estrogen receptor, expressed vimentin and CD44, and had the same in vitro chemoinvasive and chemotactic potential. Both restriction fragment length polymorphism and comparative genomic hybridization analyses of genomic DNA from these cells indicated that both subclones are of the same genetic lineage. Only the subclone with high PBR levels, however, was able to form tumors when injected in SCID mice. These data suggest that the ability of MDA-231 cells to form tumors in vivo may depend on the amount of PBR present in the cells.

Remodeling of vimentin cytoskeleton correlates with enhanced motility of promyelocytic leukemia cells during differentiation induced by retinoic acid

The intermediate filament (IFs) cytoskeleton is one of the major determinants for the mechanical properties of cytoplasm. Vimentin is the major IFs protein in peripheral blood neutrophils. We investigated its expression and function during neutrophil differentiation using the promyelocytic leukemia cell line NB4. The differentiation of NB4 cells along the neutrophil lineage and the monocytic pathway was induced by all-trans retinoic acid (ATRA) and phorbol esters (PMA), respectively. We demonstrated a down-regulation of vimentin after ATRA treatment of NB4 cells by immunoblotting and immunofluorescence. The architecture of the vimentin cytoskeleton in differentiated NB4 cells resembled that observed in mature neutrophils. In contrast, we showed a slight increase of vimentin content in phorbol ester (PMA)-treated NB4 cells. The structural features of the vimentin cytoskeleton obtained by image analysis showed significant differences in network density and directionality between ATRA-treated NB4 cells and controls. The functional consequence of the cytoskeletal remodeling for the mechanical properties of NB4 cells was assessed in migration assays. After ATRA treatment, we found a 4-fold increased migration of NB4 cells across transwell membranes with a 8 microm pore size without any cell size modification. No significant differences between PMA-treated NB4 cells and control cells could be observed using similar tests. These results indicate that both vimentin expression and network architecture are tightly controlled during neutrophil differentiation to regulate the mechanical properties of these cells.

Interferon-alpha prevents selection of doxorubicin-resistant undifferentiated-androgen-insensitive metastatic human prostate cancer cells

BACKGROUND

We determined whether treatment of metastatic prostate cancer cells with doxorubicin (DOX) and interferon-alpha (IFN-alpha) prevented the emergence of highly undifferentiated tumor cells.

METHODS

The state of cell differentiation was determined by analysis of prostate-specific antigen (PSA), E-cadherin, keratin, and vimentin.

RESULTS

Human prostate cancer LNCaP-LN3 cells growing in culture as multicell spheroids expressed higher levels of E-cadherin and E-cadherin-associated beta-catenin than LNCaP-LN3 cells growing as monolayers. Treatment of cells with DOX downregulated PSA, E-cadherin, and keratin, and upregulated expression of vimentin and vascular endothelial growth factor (VEGF) mRNA. While treatment of cells with IFN-alpha did not alter gene expression, the addition of IFN-alpha to cultures treated with DOX produced synergistic toxicity and abrogated the changes in gene expression observed in cells treated with DOX alone.

CONCLUSIONS

Treatment with IFN-alpha and DOX should be further explored as a therapeutic strategy for androgen-insensitive prostate cancer.

Structure of cell clusters formed in cultures of dissociated human embryonic brain

Cell clusters in a culture of dissociated brain from human fetuses at 8-12 weeks gestation in a serum-free growth medium were studied by immunohistochemical methods and electron microscopy. Heterogeneity of cell population in culture was demonstrated. Despite the influence of proliferation-stimulating factors, cell clusters contained not only nestin-immunopositive stem cells, but also beta-tubulin-, vimentin-, and GFAP-positive cells differentiating by the neural pathway. Stem cells were localized on the surface of clusters. The percentage of stem cells in large clusters was lower than in small clusters.

Differentiation and migration of astrocyte precursor cells and astrocytes in human fetal retina: relevance to optic nerve coloboma

The presence of astrocyte precursor cells (APCs) and time course and topography of astrocyte differentiation during development were investigated by triple-label immunohistochemistry with intact fetal and adult human retinas. Throughout retinal development and adulthood, expression of Pax2 was restricted to cells of the astrocytic lineage. Three distinct stages of astrocytic differentiation were identified during development: i) Pax2+/vimentin+/GFAP- APCs; ii) Pax2+/vimentin+/GFAP+ immature perinatal astrocytes; and iii) Pax2+/vimentin-/GFAP+ mature perinatal astrocytes. In adult, cells with the antigenic phenotype of mature perinatal astrocytes were restricted to a region surrounding the optic nerve head (ONH), whereas cells at a fourth stage of differentiation, adult astrocytes (Pax2-/vimentin-/GFAP+), were apparent throughout the vascularized retina. APC appearance was centered around the ONH and preceded the appearance of perinatal astrocytes. A cluster of Pax2+ somas was also present in a small region surrounding the ONH at the ventricular surface of the developing retina, which suggests the existence of two distinct sites of astrocytic differentiation. The coincidence in the location of APCs and perinatal astrocytes at the ventricular zone with that of optic nerve colobomas, together with the association of Pax2 gene mutations with this condition, suggests that coloboma formation may result from impaired astrocyte differentiation during development.

Type II glucocorticoid receptors are involved in neuronal death and astrocyte activation induced by trimethyltin in the rat hippocampus

According to our previous study, trimethyltin (TMT), a neurotoxicant, induces the loss of pyramidal neurons in the rat hippocampus, which is preceded by a transient increase in plasma corticosterone concentration. To address whether this transient activation of the hypothalamopituitary-adrenocortical axis is related to neuronal loss in the hippocampus, we evaluated the effects of bilateral adrenalectomy (ADX) and the chronic supplemental treatment of glucocorticoid receptor agonists after ADX on TMT-induced hippocampal damage. Peroral administration of a single dose of TMT (9 mg/kg body wt) induced the extensive loss of CA3 pyramidal neurons and reactive astrocytosis in the hippocampus, as evidenced by results of vimentin and glial fibrillary acidic protein immunohistochemistry, and the effects were profoundly exacerbated by bilateral adrenalectomy. Prolonged administration of corticosterone not only attenuated the exacerbating effects of adrenalectomy but also partially reversed the TMT-induced neuronal loss and reactive astrocytosis. Dexamethasone, but not aldosterone, could be substituted for corticosterone, suggesting a novel neuroprotective action of type II glucocorticoid receptors in the hippocampus.

[Expression of vimentin in lens epithelial cells of age-related cataract]

OBJECTIVE

To observe the expression of vimentin in the lens epithelial cells and superficial cortex of age-related cataract.

METHODS

Twenty-six paraformaldehyde-fixed flat preparations of human lens epithelium attached to the anterior capsule and obtained during extracapsular cataract extraction were studied. Of these, 22 were studied and compared to the 10 samples from normal lenses with antibody to vimentin by avidinbiotinylated peroxidase complex (ABC) method and observed with a light microscope, and 6 (4 cataractous and 2 normal) were used for pre-embedding immunoelectron microscopy. Vimentin in superficial layers (epithelium and superficial cortex) of 4 cataractous lenses were analysed by SDS-polyacrylamide gel electrophoresis (PAGE) and Western blot method.

RESULTS

The average gray level values for expression of vimentin were 143.84 +/- 8.52 and 134.87 +/- 14.27 in cataract and normal group, respectively (t = 2.0948, P < 0.05). Ultrastructure of epithelial cells showed a decrease of intermediate filaments, accumulation of vimentin in bundle and organelle degeneration. Vimentin was identified in the superficial layers of normal and immature cataractous lenses by SDS-PAGE and Western blot. In another two mature cataractous lenses, little vimentin was detected.

CONCLUSION

Decrease of vimentin may be initiated by damage to the epithelial cells leading to degradation of cytoskeleton, and appears to be related with the formation of age-related cataract.

Expression of the intermediate filament protein nestin by sustentacular cells in mature olfactory neuroepithelium

The intermediate filament protein nestin has been widely used as a marker for proliferating neural progenitor cells in the nervous system. The mammalian olfactory neuroepithelium is a region of the nervous system that robustly supports ongoing neurogenesis, yet where nestin has not been reported to mark proliferating progenitors. Using immunohistochemistry, we examined nestin expression in the mature olfactory neuroepithelium and found it to be tightly restricted to the basal compartment where the olfactory neuronal progenitor cell population resides. The pattern of nestin immunoreactivity was consistent with expression by the endfeet and inferior processes of sustentacular cells rather than basal cells. Using a bank of defined antibody markers, we confirmed nestin's pattern of distribution to be different from that of cytokeratin, vimentin, GBC-1, GAP43, and carnosine. It was highly similar to the pattern of SUS-4 immunoreactivity in the basal region of the neuroepithelium. Following surgical bulbectomy, nestin expression was up-regulated and became evident in the cell bodies of sustentacular cells situated more apically in the neuroepithelium. We have shown nestin to be present in the basal region of the adult olfactory neuroepithelium in the zone that supports ongoing neurogenesis in the adult, but its expression is restricted to the inferior parts of sustentacular cells rather than the neuronal progenitor cells. Nestin may play a potential role in the migration of recently proliferated olfactory neurons on the scaffolding of sustentacular cells in a manner analogous to its proposed role in radial glia during embryonic development of the central nervous system.

Rigidity of circulating lymphocytes is primarily conferred by vimentin intermediate filaments

Lymphocytes need rigidity while in circulation, but must abruptly become deformable to undergo transmigration into tissue. Previously, the control of leukocyte deformability has been attributed to microfilaments or microtubules, but the present studies demonstrate the greater importance of vimentin intermediate filaments (IFs). In circulating T lymphocytes, IFs form a distinctive spherical cage that undergoes a rapid condensation into a juxtanuclear aggregate during chemokine-induced polarization. Measurements of the resistance of peripheral blood T lymphocytes to global deformation demonstrate that their rigidity is primarily dependent on intact vimentin filaments. Microtubules, in contrast, are not sufficient to maintain rigidity. Thus, vimentin IFs are a primary source of structural support in circulating human lymphocytes, and their regulated collapse is likely to be an essential element in chemokine-induced transendothelial migration.

Inactivation of the glial fibrillary acidic protein gene, but not that of vimentin, improves neuronal survival and neurite growth by modifying adhesion molecule expression

Intermediate filaments (IFs) are a major component of the cytoskeleton in astrocytes. Their role is far from being completely understood. Immature astrocytes play a major role in neuronal migration and neuritogenesis, and their IFs are mainly composed of vimentin. In mature differentiated astrocytes, vimentin is replaced by the IF protein glial fibrillary acidic protein (GFAP). In response to injury of the CNS in the adult, astrocytes become reactive, upregulate the expression of GFAP, and reexpress vimentin. These modifications contribute to the formation of a glial scar that is obstructive to axonal regeneration. Nevertheless, astrocytes in vitro are considered to be the ideal substratum for the growth of embryonic CNS axons. In the present study, we have examined the potential role of these two major IF proteins in both neuronal survival and neurite growth. For this purpose, we cocultured wild-type neurons on astrocytes from three types of knock-out (KO) mice for GFAP or/and vimentin in a neuron-astrocyte coculture model. We show that the double KO astrocytes present many features of immaturity and greatly improve survival and neurite growth of cocultured neurons by increasing cell-cell contact and secreting diffusible factors. Moreover, our data suggest that the absence of vimentin is not a key element in the permissivity of the mutant astrocytes. Finally, we show that only the absence of GFAP is associated with an increased expression of some extracellular matrix and adhesion molecules. To conclude, our results suggest that GFAP expression is able to modulate key biochemical properties of astrocytes that are implicated in their permissivity.