PEG-Filgrastim activity on granulocyte functions.
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Actins↗
Biomedical subjects
Letizia Mattii
Publications and source records attributed to Letizia Mattii.
Actin polymerization in neutrophils from donors of peripheral blood stem cells: divergent effects of glycosylated and nonglycosylated recombinant human granulocyte colony-stimulating factor.
Neutrophil functions can be modified by Recombinant human G-CSF (rhG-CSF) treatment, with divergent effects on phagocytosis, motility, bactericidal activity, and surface molecule expression. Neutrophil morphology is modified by treatment with filgrastim (the nonglycosylated form of rhG-CSF), while it is not affected by lenograstim (the glycosylated type of rhG-CSF). Little information is available about actin polymerization in neutrophils from subjects treated with the two types of rhG-CSF. In the current paper we evaluated two groups of donors of peripheral blood stem cells (PBSC) for allogeneic transplantation. Ten subjects were treated with filgrastim and 10 with lenograstim to mobilize PBSC; 15 blood donors were evaluated as a control group. Actin polymerization (both spontaneous and fMLP-stimulated) was studied by a flow cytometric assay. A microscopic fluorescent assay was also carried out to evaluate F-actin distribution in neutrophils. We found that filgrastim induced an increased F-actin content in resting neutrophils, along with morphologic evidence for increased actin polymerization distributed principally at the cell membrane and frequently polarized in focal areas; in addition, fMLP was not able to induce further actin polymerization. On the contrary, treatment with lenograstim was associated with F-actin content, distribution, and polymerization kinetics indistinguishable from those displayed by control neutrophils. Such experimental results show that filgrastim and lenograstim display divergent effects also on neutrophil actin polymerization and provide further explanation for previous experimental findings.
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TSH-Dependent expression of the LDL receptor-associated protein (RAP) in thyroid epithelial cells.
The low density lipoprotein (LDL) receptor-associated protein (RAP) is an endoplasmic reticulum (ER)-resident molecular chaperone for several LDL receptor family members and it also binds to thyroglobulin (Tg), the thyroid hormone precursor. Disruption of the RAP gene in thyrocytes results in impaired Tg secretion. To gain further insights into the function of RAP in the thyroid, we investigated whether its expression in thyrocytes is regulated by thyroid-stimulating hormone (TSH), a feature common to all proteins involved in thyroid hormone secretion. We found by immunofluorescence that in FRTL-5 cells cultured in the presence of TSH, RAP is expressed intracellularly. The levels of expression increased after exposure to TSH, beginning at 48 hours, in a concentration-dependent manner as observed by immunofluorescence and Western blotting. Expression of RAP was also increased by TSH in primary cultures of human thyrocytes as observed by Western blotting. In hypothyroid mice with high serum TSH, RAP was markedly increased compared with euthyroid mice as observed by immunohistochemistry and Western blotting. Based on these findings, we concluded that RAP is expressed by thyrocytes in a TSH-dependent manner, both in cultured thyroid cells and in vivo.
Animals↗
Thyroid dysfunction in megalin deficient mice.
Megalin mediates transcytosis of thyroglobulin (Tg), the thyroid hormone precursor, resulting in its passage into the bloodstream. The process involves especially hormone-poor Tg, which may favour hormone secretion by preventing competition with hormone-rich Tg for proteolytic degradation. To gain more insight into the role of megalin, here we studied thyroid function and histology in megalin deficient mice compared with WT mice. As expected from the knowledge that megalin mediates Tg transcytosis, serum Tg levels were significantly reduced in homozygous (megalin-/-) mice, which, more importantly, were found to be hypothyroid, as demonstrated by significantly reduced serum free thyroxine and significantly increased serum thyroid stimulating hormone (TSH) levels. In heterozygous (megalin+/-) mice, in which megalin expression was normal, thyroid function was unaffected. Although the serological phenotype in megalin-/- mice was not associated with histological alterations or goiter, our results support a major role of megalin in thyroid hormone secretion.
Animals↗
Kidney expression of RhoA, TGF-beta1, and fibronectin in human IgA nephropathy.
BACKGROUND: The Rho/transforming growth factor-beta (TGF-beta) system plays a crucial role in the progression of renal damage due to stimulation of extracellular matrix molecule deposition. In fact, the in vitro TGF-beta-mediated production of fibronectin, one of the major TGF-beta-regulated extracellular components, has recently been correlated with Rho protein signalling molecules. Although a close relationship between increased renal tissue levels of TGF-beta1 and fibronectin has been reported in IgA nephropathy, no data are available on renal tissue expression of Rho proteins. METHODS: This study was designed to assess in IgA nephropathy patients the kidney tissue immunohistochemical expression of RhoA, TGF-beta1, and fibronectin, and the rate of immunoreactivity for each antigen by image analysis. RESULTS: An increase in RhoA, TGF-beta1, and fibronectin expression was detected in tubulointerstitium and in glomeruli of IgA nephropathy compared to normal kidneys; in particular, RhoA was found also in proximal tubules, unlike control kidneys and mainly at the cell boundary level, which is in keeping with its activated form. The image analysis confirmed that the kidney tissue levels of RhoA, TGF-beta1, and fibronectin were significantly enhanced in the patients. CONCLUSION: This study suggests that RhoA may represent a key molecule in the signalling transduction pathway of profibrotic signals in IgA nephropathy.
Adolescent↗
Glycosylated or non-glycosylated G-CSF differently influence human granulocyte functions through RhoA.
Granulocyte function may be altered after in vivo G-CSF administration and this has been related to both an immaturity of mobilized cells and to a defect in F-actin polymerization. In this paper we show that in resting Filgrastim (non-glycosylated G-CSF)-pulsed cells, F-actin polymerization, membrane-linked RhoA and cell polarization are enhanced compared to those found in resting Lenograstim (glycosylated G-CSF)-cells. The basal hyper-activation of RhoA could be responsible for the morphological and functional modifications of Filgrastim-mobilized cells. Moreover, Filgrastim-mobilized cells, but not Lenograstim-mobilized cells, are unable to correctly respond to LPS stimulation, as demonstrated by minor further RhoA activation and cell elongation.
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Carboxy-terminal fragment of osteogenic growth peptide regulates myeloid differentiation through RhoA.
The carboxy-terminal fragment of osteogenic growth peptide, OGP(10-14), is a pentapeptide with bone anabolic effects and hematopoietic activity. The latter activity appears to be largely enhanced by specific growth factors. To study the direct activity of OGP(10-14) on myeloid cells, we tested the pentapeptide proliferating/differentiating effects in HL60 cell line. In this cell line, OGP(10-14) significantly inhibited cell proliferation, and enhanced myeloperoxidase (MPO) activity and nitroblue tetrazolium reducing ability. Moreover, it induced cytoskeleton remodeling and small GTP-binding protein RhoA activation. RhoA, which is known to be involved in HL60 differentiation, mediated these effects as shown by using its specific inhibitor, C3. Treatment with GM-CSF had a comparable OGP(10-14) activity on proliferation, MPO expression, and RhoA activation. Further studies on cell proliferation and RhoA activation proved enhanced activity by association of the two factors. These results strongly suggest that OGP(10-14) acts directly on HL60 cells by activating RhoA signaling although other possibilities cannot be ruled out.
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Cellular and subcellular localization of the small G protein RhoA in the human and rat embryonic and adult kidney.
Rho proteins, a subgroup of the Ras GTPase superfamily, control many cellular processes and morphogenetic events by acting as signaling molecules in the transduction pathways of various receptors. Among the "Rho-dependent" receptors are the extracellular matrix- and growth factor-binding sites; these are particularly involved in the modulation of renal development since they control the epithelial-mesenchymal interactions that drive kidney organogenesis. The present study has addressed the immunohistochemical localization of RhoA in developing and adult kidneys of rats and humans because: a) Rho proteins are known to have a morphogenetic role, b) data in the literature on expression of Rho GTPases during mammalian histogenesis and organogenesis are scarce, and c) their involvement in the transduction pathways of receptors is implicated in kidney development. In particular, RhoA peptide was found to be localized in the mesonephric duct and vesicles in both rats and humans; metanephric anlagen were mainly stained in ampullar-derived cells. Periglomerular tubules of fetal and adult kidneys as well as collecting ducts of adult kidneys showed intense staining. Therefore, the present study provides new information on the distribution patterns of RhoA during early stages of mammalian kidney development suggesting that this signaling molecule may take part in epithelial-mesenchymal induction processes that control kidney organogenesis. RhoA expression in adult structures may be linked with renewal of renal epithelial cells and the maintenance of their morphology and polarity.
Animals↗
Effect of heparan sulphate on kidney tissue expression of TGF-beta, rhoA, laminin and fibronectin in subtotally nephrectomized rats.
BACKGROUND: Different mitogens are involved in the pathogenesis of kidney damage after subtotal nephrectomy. One of them, TGF-beta, controls mesangial cell proliferation and interstitial fibrosclerosis. The transduction of the TGF-beta signal is controlled by intracellular signalling molecules such as Ras G monomeric proteins. Renal damage after subtotal nephrectomy (5/6 Nx) can be prevented by heparins, but so far no immunohistochemical correlation between TGF-beta, TGF-beta induced matrix molecules and Rho proteins has been investigated. Since the Ras transduction pathway has recently been associated with progression of renal damage, we evaluated the effect of heparan sulphate (HS) on the expression of TGF-beta, laminin, fibronectin and a Ras protein, RhoA, in the rat remnant kidney model. METHODS: The immunoperoxidase technique was employed to reveal the antigens on 18 remnant kidneys from 5/6 nephrectomized rats, nine untreated and nine treated with oral HS, and on seven normal kidneys from sham-operated rats. Data were semiquantitatively analyzed by an image analyzer (Quantimet, Leica). RESULTS: The expression of the antigens was significantly higher in the remnant kidneys than in normals. The high TGF-beta, laminin, fibronectin and RhoA expression observed in subtotally nephrectomized rats suggests a role for these molecules in the pathogenesis of progressive renal damage. However, apart from RhoA, HS-treated rats had significantly lower levels of the antigens than the untreated rats. CONCLUSIONS: HS treatment is associated with significantly lower renal expression of TGF-beta, laminin and fibronectin, but not of RhoA. This suggests that the renal-protective effect of HS may be obtained by modulating the TGF-beta pathway, independently of RhoA-mediated transduction.
Analysis of Variance↗