Molecular cloning of a complementary DNA encoding human macrophage-specific colony-stimulating factor (CSF-1)

Liver fibrosis

Knowledge on the development and progression of liver fibrosis has grown exponentially in the past decade. At present, liver fibrogenesis is referred to as a dynamic process involving complex cellular and molecular mechanisms, resulting from the chronic activation of the tissue repair mechanisms that follows reiterated liver tissue injury. The identification and characterization of the cell types and of the different mediators involved in this process has allowed a "re-visitation" of several issues related to liver cirrhosis and its immediate consequences. Among these, evaluation of the relationships occurring between fibrogenesis and portal hypertension, cholestasis and the development of hepatocellular carcinoma, represent some of the hottest areas of research in this field of hepatology. The elucidation of many of the cellular and molecular mechanisms responsible for the progression of liver fibrosis has provided a sound basis for the development of pharmacological strategies able to modulate this important pathophysiological process.

Inhibition of the Differentiation of Dendritic Cells From CD34+ Progenitors by Tumor Cells: Role of Interleukin-6 and Macrophage Colony-Stimulating Factor

The escape of malignant cells from the immune response against the tumor may result from a defective differentiation or function of professional antigen-presenting cells (APC), ie, dendritic cells (DC). To test this hypothesis, the effect of human renal cell carcinoma cell lines (RCC) on the development of DC from CD34+progenitors was investigated in vitro. RCC cell lines were found to release soluble factors that inhibit the differentiation of CD34+ cells into DC and trigger their commitment towards monocytic cells (CD14+CD64+CD1a−CD86−CD80−HLA-DRlow) with a potent phagocytic capacity but lacking APC function. RCC CM were found to act on the two distinct subpopulations emerging in the culture at day 6 ([CD14+CD1a−] and [CD14−CD1a+]) by inhibiting the differentiation into DC of [CD14+CD1a−] precursors and blocking the acquisition of APC function of the [CD14−CD1a+] derived DC. Interleukin-6 (IL-6) and macrophage colony-stimulating factor (M-CSF) were found to be responsible for this phenomenon: antibodies against IL-6 and M-CSF abrogated the inhibitory effects of RCC CM; and recombinant IL-6 and/or M-CSF inhibited the differentiation of DC similarly to RCC CM. The inhibition of DC differentiation by RCC CM was preceeded by an induction of M-CSF receptor (M-CSFR; CD115) and a loss of granulocyte-macrophage colony-stimulating factor receptor  (GM-CSFR; CD116) expression at the surface of CD34+cells, two phenomenon reversed by anti–IL-6/IL-6R and anti–M-CSF antibodies, respectively. Finally, a panel of tumor cell lines producing IL-6 and M-CSF induced similar effects. Taken together, the results suggest that the inhibition of DC development could represent a frequent mechanism by which tumor cells will escape immune recognition.

Inhibition of the Differentiation of Dendritic Cells From CD34+ Progenitors by Tumor Cells: Role of Interleukin-6 and Macrophage Colony-Stimulating Factor

The escape of malignant cells from the immune response against the tumor may result from a defective differentiation or function of professional antigen-presenting cells (APC), ie, dendritic cells (DC). To test this hypothesis, the effect of human renal cell carcinoma cell lines (RCC) on the development of DC from CD34+progenitors was investigated in vitro. RCC cell lines were found to release soluble factors that inhibit the differentiation of CD34+ cells into DC and trigger their commitment towards monocytic cells (CD14+CD64+CD1a−CD86−CD80−HLA-DRlow) with a potent phagocytic capacity but lacking APC function. RCC CM were found to act on the two distinct subpopulations emerging in the culture at day 6 ([CD14+CD1a−] and [CD14−CD1a+]) by inhibiting the differentiation into DC of [CD14+CD1a−] precursors and blocking the acquisition of APC function of the [CD14−CD1a+] derived DC. Interleukin-6 (IL-6) and macrophage colony-stimulating factor (M-CSF) were found to be responsible for this phenomenon: antibodies against IL-6 and M-CSF abrogated the inhibitory effects of RCC CM; and recombinant IL-6 and/or M-CSF inhibited the differentiation of DC similarly to RCC CM. The inhibition of DC differentiation by RCC CM was preceeded by an induction of M-CSF receptor (M-CSFR; CD115) and a loss of granulocyte-macrophage colony-stimulating factor receptor  (GM-CSFR; CD116) expression at the surface of CD34+cells, two phenomenon reversed by anti–IL-6/IL-6R and anti–M-CSF antibodies, respectively. Finally, a panel of tumor cell lines producing IL-6 and M-CSF induced similar effects. Taken together, the results suggest that the inhibition of DC development could represent a frequent mechanism by which tumor cells will escape immune recognition.

Retinoic Acid Inhibits Monocyte to Macrophage Survival and Differentiation

Vitamin A metabolites are potent differentiation-inducing agents for myelomonocytic cell lines in vitro and are successfully used for the treatment of patients with acute promyelocytic leukemia. However, little is known about the effects of vitamin A on normal hematopoietic cells. Therefore, we investigated the effect of vitamin A on differentiation and activation of human blood monocytes (MO). Culturing MO for up to 4 days with 9-cis retinoic acid (RA) and all-trans RA but not retinol reduced MO survival, with the remaining cells being morphologically comparable to control cells. Because macrophage colony-stimulating factor (M-CSF) is a well-known survival factor for MO, we measured the M-CSF content of MO culture supernatants using enzyme-linked immunosorbent assay and found that RA suppressed the constitutive secretion of M-CSF. Northern analysis showed that the M-CSF mRNA expression was only slightly reduced by RA treatment, suggesting regulation on the posttranscriptional level. In contrast to MO, M-CSF secretion by MO-derived macrophages (MAC) was not altered by RA, suggesting a differentiation-dependent switch in the responsiveness of MO/MAC to RA. Because M-CSF is not only a survival-promoting but also a differentiation-promoting factor for myeloid cells, we analyzed the effect of RA on MO to MAC maturation. RA suppressed the expression of the maturation-associated antigen carboxypeptidase M (CPM)/MAX.1 at both the protein and mRNA levels and modulated the lipopolysaccharide-stimulated cytokine secretion of MO/MAC. The addition of exogenous M-CSF to RA-containing MO cultures fails to overcome the RA-induced inhibition of MO differentiation. However, the survival rate was improved by exogenous M-CSF. We conclude that RA acts via two different mechanisms on monocyte survival and differentiation: posttranscriptionally by controlling M-CSF secretion, which decreases MO survival, and transcriptionally regulating the expression of differentiation-associated genes. The regulation of M-CSF production may contribute to the antileukemic effect of RA in vivo by reducing autocrine M-CSF production by leukemic cells.

Retinoic Acid Inhibits Monocyte to Macrophage Survival and Differentiation

Vitamin A metabolites are potent differentiation-inducing agents for myelomonocytic cell lines in vitro and are successfully used for the treatment of patients with acute promyelocytic leukemia. However, little is known about the effects of vitamin A on normal hematopoietic cells. Therefore, we investigated the effect of vitamin A on differentiation and activation of human blood monocytes (MO). Culturing MO for up to 4 days with 9-cis retinoic acid (RA) and all-trans RA but not retinol reduced MO survival, with the remaining cells being morphologically comparable to control cells. Because macrophage colony-stimulating factor (M-CSF) is a well-known survival factor for MO, we measured the M-CSF content of MO culture supernatants using enzyme-linked immunosorbent assay and found that RA suppressed the constitutive secretion of M-CSF. Northern analysis showed that the M-CSF mRNA expression was only slightly reduced by RA treatment, suggesting regulation on the posttranscriptional level. In contrast to MO, M-CSF secretion by MO-derived macrophages (MAC) was not altered by RA, suggesting a differentiation-dependent switch in the responsiveness of MO/MAC to RA. Because M-CSF is not only a survival-promoting but also a differentiation-promoting factor for myeloid cells, we analyzed the effect of RA on MO to MAC maturation. RA suppressed the expression of the maturation-associated antigen carboxypeptidase M (CPM)/MAX.1 at both the protein and mRNA levels and modulated the lipopolysaccharide-stimulated cytokine secretion of MO/MAC. The addition of exogenous M-CSF to RA-containing MO cultures fails to overcome the RA-induced inhibition of MO differentiation. However, the survival rate was improved by exogenous M-CSF. We conclude that RA acts via two different mechanisms on monocyte survival and differentiation: posttranscriptionally by controlling M-CSF secretion, which decreases MO survival, and transcriptionally regulating the expression of differentiation-associated genes. The regulation of M-CSF production may contribute to the antileukemic effect of RA in vivo by reducing autocrine M-CSF production by leukemic cells.

Heterozygous osteopetrotic (op) mutation reduces atherosclerosis in LDL receptor- deficient mice

Previous studies of osteopetrotic (op) mice lacking macrophage colony-stimulating factor (M-CSF) have revealed an inhibition of atherosclerosis development in the apolipoprotein E (apo E)-deficient model and in a diet-induced model. Using LDL receptor-deficient mice, we now show that atheroma development depends on M-CSF concentration, as not only did homozygous osteopetrotic (op/op) mice have dramatically reduced lesions (approximately 0.3% of control lesion size) but heterozygous (op/+) mice had lesions < 1% of controls. Mice heterozygous for the op mutation (op/+) had plasma levels of M-CSF about half those in controls (+/+). The finding that an approximately 2-fold reduction in M-CSF expression reduced lesion size approximately 100-fold suggests the requirement for a threshold level of M-CSF. The effect of M-CSF on atherosclerosis did not appear to be mediated either by changes in plasma lipoprotein levels or alterations in the number of circulating monocytes, since both op/op and op/+ mice exhibited higher levels of atherogenic lipoprotein particles and (op/+) mice showed a near normal number of circulating monocytes. LDL receptor-null littermates of genotypes from op/op, op/+, to +/+ showed monocyte differentials of approximately 4.5, 8, and 10%, respectively. Taken together, these results suggest that the effects of M-CSF on atherogenesis may not be mediated by expression of M-CSF systemically or by modulation of the number of circulating monocytes. These studies support the conclusion that M-CSF participates critically in fatty streak formation and progression to a complex fibrous lesion.

Cloning and sequencing of cDNA encoding bovine macrophage colony-stimulating factor (bM-CSF) and expression of recombinant bM-CSF using baculovirus

The cDNAs encoding bovine macrophage colony-stimulating factors alpha and beta (M-CSF alpha and M-CSF beta) were cloned and recombinant bovine M-CSF alpha (rbM-CSF beta) in its dimeric form was expressed by using a recombinant baculovirus/insect cell system. The predicted amino acid sequence of rbM-CSF alpha and rbM-CSF beta shared 83.3 and 75.9% (alpha), 75.3 and 65.9% (beta) similarity with the sequence for human and murine M-CSFs, respectively. The biological activity of rbM-CSF beta was confirmed by the colony-forming assay using mouse bone marrow cells. SDS-PAGE under a reducing condition showed that the molecular weight of rbM-CSF beta was approximately 34 kDa. On the other hand, Western blot analysis under a non-reducing condition revealed that this rbM-CSF beta was secreted in dimeric form into the cell supernatant.

The Effects of Colony-Stimulating Factor-1 on the Distribution of Mononuclear Phagocytes in the Developing Osteopetrotic Mouse

Colony-stimulating factor-1 (CSF-1), the primary regulator of mononuclear phagocyte (M▹) production, exists as either a circulating or cell surface, membrane-spanning molecule. To establish transplacental transfer of maternal CSF-1, gestational day-17 mothers were injected intravenously with 125I-mouse CSF-1 or human rCSF-1, and the 125I-cpm or human CSF-1 concentrations were measured in fetal tissue, placenta, and fetal/maternal sera. Biologically active CSF-1 crossed the placenta and peaked in fetal tissue, placenta, and serum 10 minutes after injection. The role of CSF-1 in perinatal M▹ development was examined by studying the CSF-1–deficient osteopetrotic (csfmop/csfmop) mouse. Fetal/neonatal mice, derived from matings of either +/csfmopfemales with csfmop/csfmop males or the reciprocal pairings, were genotyped and tissue M▹ identified and quantified. In the presence of circulating maternal CSF-1 (+/csfmop mother), M▹ development incsfmop/csfmop liver was essentially complete at birth relative to +/csfmoplittermates, but significantly reduced in spleen, kidney, and lung. In the absence of circulating maternal CSF-1 (csfmop/csfmop mother), M▹ numbers at birth were reduced in csfmop/csfmopliver relative to the offspring of +/csfmopmothers, but were similar in spleen, kidney, and lung. We conclude that CSF-1 is required for the perinatal development of most M▹ in these tissues. Compensation for total absence of local CSF-1 production by circulating, maternal CSF-1 is tissue-specific and most prominent in liver, the first fetal organ perfused by placental blood. However, because some M▹ developed in the complete absence of CSF-1, other factors must also be involved in the regulation of macrophage development.

The Effects of Colony-Stimulating Factor-1 on the Distribution of Mononuclear Phagocytes in the Developing Osteopetrotic Mouse

Colony-stimulating factor-1 (CSF-1), the primary regulator of mononuclear phagocyte (M▹) production, exists as either a circulating or cell surface, membrane-spanning molecule. To establish transplacental transfer of maternal CSF-1, gestational day-17 mothers were injected intravenously with 125I-mouse CSF-1 or human rCSF-1, and the 125I-cpm or human CSF-1 concentrations were measured in fetal tissue, placenta, and fetal/maternal sera. Biologically active CSF-1 crossed the placenta and peaked in fetal tissue, placenta, and serum 10 minutes after injection. The role of CSF-1 in perinatal M▹ development was examined by studying the CSF-1–deficient osteopetrotic (csfmop/csfmop) mouse. Fetal/neonatal mice, derived from matings of either +/csfmopfemales with csfmop/csfmop males or the reciprocal pairings, were genotyped and tissue M▹ identified and quantified. In the presence of circulating maternal CSF-1 (+/csfmop mother), M▹ development incsfmop/csfmop liver was essentially complete at birth relative to +/csfmoplittermates, but significantly reduced in spleen, kidney, and lung. In the absence of circulating maternal CSF-1 (csfmop/csfmop mother), M▹ numbers at birth were reduced in csfmop/csfmopliver relative to the offspring of +/csfmopmothers, but were similar in spleen, kidney, and lung. We conclude that CSF-1 is required for the perinatal development of most M▹ in these tissues. Compensation for total absence of local CSF-1 production by circulating, maternal CSF-1 is tissue-specific and most prominent in liver, the first fetal organ perfused by placental blood. However, because some M▹ developed in the complete absence of CSF-1, other factors must also be involved in the regulation of macrophage development.

Identification of alternatively spliced transcripts encoding murine macrophage colony-stimulating factor

We have isolated a novel cDNA encoding macrophage colony-stimulating factor (M-CSF) from a murine stromal cell line, ST2. The cDNA included an entire coding sequence of the M-CSF gene but contained an additional sequence of 140 base pairs (bp). Northern blot analysis demonstrated that other murine cell lines such as a fibroblastic cell line (L) and a stromal cell line (PA6) also expressed the transcripts corresponding to the clone. The nucleotide sequence analyses of the cDNA and the cloned M-CSF genome revealed that the 140-bp insertion sequence was part of intron 1 which separated exon 1 and exon 2: the former contained part of the amino acid residues of the signal sequence and the latter the rest of the signal sequence and the first 22 amino acid residues of the mature protein. The insertion of the 140-bp intron sequence not only changed the amino acid sequence of the signal peptide but also generated an in-frame termination codon. However, instead of the dysfunction of the original initiation codon, the 140-bp insertion sequence contained a putative ATG initiation codon that preserved the original open reading frame. Finally, we found that the cDNA directed the expression of a secreted and biologically active M-CSF protein when it was introduced into COS7 cells and M-CSF activity in the culture supernatants was measured using an M-CSF-dependent cell line. These results indicate the presence of an alternatively spliced M-CSF transcript which utilizes an alternate initiation codon in order to specify active M-CSF protein.

The cell-surface form of colony-stimulating factor-1 is regulated by osteotropic agents and supports formation of multinucleated osteoclast-like cells

Colony-stimulating factor-1 (CSF-1) is a hematopoietic growth factor that is released by osteoblasts and is recognized to play a critical role in bone remodeling in vivo and in vitro. CSF-1 is synthesized as a soluble or cell-surface protein. It is unclear, however, whether human osteoblasts express both molecular forms of CSF-1, and whether these isoforms can independently mediate osteoclastogenesis. In the present study, using a combination of quantitative reverse transcriptase polymerase chain reaction, flow cytometry, and Western immunoblot analysis, we have demonstrated that human osteoblast-like cells as well as primary human osteoblasts express the cell-surface form of CSF-1 both constitutively and in response to parathyroid hormone and tumor necrosis factor. Furthermore, using an in vitro co-culture system, we have shown that cell-surface CSF-1 alone is sufficient to support osteoclast formation. These findings may be especially significant in view of evidence that direct cell-to-cell contact is critical for osteoclast formation, and suggest that differential regulation of expression of the CSF-1 isoforms may influence osteoclast function modulated by osteotropic hormones.

Expression and function of colony-stimulating factors and their receptors in human prostate carcinoma cell lines

BACKGROUND

The predeliction for prostate carcinoma cells to metastasize to bone suggests the hypothesis that bone and/or bone marrow-derived factors may promote prostate carcinoma cell growth or survival, or serve as chemoattractants for these cells.

METHODS

We screened three prostate carcinoma cell lines, DU-145, PC-3, and LNCaP, for the expression of several hematopoiesis-associated colony-stimulating factors (CSFs) and their receptors using RT-PCR (reverse transcriptase-polymerase chain reaction) and immunohistochemical methods, and examined their functional effects.

RESULTS

All of these cell lines express granulocyte-macrophage colony-stimulating factor (GM-CSF) and macrophage colony-stimulating factor (M-CSF), and the DU-145 and PC-3 lines express stem-cell factor (SCF), as determined by RT-PCR and ELISA. Each of these cell lines expresses the receptors for SCF, GM-CSF, M-CSF, and granulocyte colony-stimulating factor (G-CSF). M-CSF enhanced the soft-agar clonogenicity of PC-3 and DU-145 cells, and GM-CSF stimulated all three cell lines. SCF stimulated the clonogenic growth of DU-145 cells. G-CSF marginally abrogated the induction of cell death in the PC-3 and LNCaP cell lines under serum-free conditions. GM-CSF and M-CSF stimulated modest chemotaxis of PC-3, DU-145, and LNCaP cells (most prominently in PC-3 cells).

CONCLUSIONS

These data suggest that 1) CSFs may be part of a network of paracrine and autocrine loops that modulate prostate carcinoma cell activity, and 2) the growth-stimulatory, survival-enhancing, and/or chemotactic actions of bone marrow-derived CSFs on prostate carcinoma cells may explain in part why bone is a preferential site of prostatic carcinoma metastases.

Production of granulocyte/macrophage and macrophage colony-stimulating factors by human thyrocytes in culture

Monocytes/macrophages can be activated by the colony-stimulating factors (CSFs), granulocyte/macrophage CSF and macrophage CSF, and play a pivotal role in immune and inflammatory responses. We examined whether human thyrocytes can produce these CSFs. Interleukin-1 (IL-1) strongly up-regulated the gene and protein expression of the two CSFs. Interferon-gamma stimulated M-CSF expression but inversely suppressed GM-CSF expression in either basal or IL-1-stimulated condition. Thyrocytes prepared from Graves' thyroid tissues produced relatively larger amounts of GM-CSF in response to IL-1 and M-CSF in both basal and IL-1-stimulated conditions when compared to those obtained from normal and adenomatous goiter thyroid tissues. Thyrotropin attenuated M-CSF, but not GM-CSF, production. The present finding indicates that human thyrocytes themselves produce both GM-CSF and M-CSF, and thus may participate in immune and inflammatory responses through these CSFs production.

The carboxyl-terminal valine residues of proTGF alpha are required for its efficient maturation and intracellular routing

Soluble forms of transforming growth factor-alpha (TGF alpha) are derived by proteolytic processing of an integral membrane glycoprotein precursor (pro TGF alpha). Previous studies indicated that phorbol ester-induced cleavage of pro TGF alpha in CHO cells is dependent on the presence of a valine residue located at the carboxyl terminus of the precursor's cytoplasmic domain. We reassessed this requirement with epitope-tagged constructs introduced into transformed rat liver epithelial cells that normally express and process TGF alpha. We found that pro TGF alpha mutants lacking the terminal valine residues showed greatly reduced maturation to the fully glycosylated form. Additionally, they were present at substantially reduced levels on the cell surface and, instead, accumulated in the endoplasmic reticulum. Consistent with these results, enzyme-linked immunosorbent assay (ELISA) and Western blot analyses revealed little or no soluble TGF alpha in medium conditioned by cells expressing the mutant constructs. Finally, a truncated pro TGF alpha mutant lacking most of the cytoplasmic domain but retaining a carboxyl-terminal valine was processed and cleaved in a near-normal manner. These results, some of which were reproduced in CHO cells, indicate that the predominant effect of the carboxyl-terminal valines is to ensure normal maturation and routing of the precursor.

Localization of a gene for autosomal dominant osteopetrosis (Albers-Schönberg disease) to chromosome 1p21

Albers-Schönberg disease, the classical form of osteopetrosis, is an autosomal dominant condition with generalized increased skeletal density due to reduced bone resorption. Characteristic radiological findings are generalized osteosclerosis, with, most typically, end-plate sandwichlike thickening of the vertebrae (Rugger-Jersey spine) and the bone-within-bone (endobones) phenomenon. We studied an extended kindred with Albers-Schönberg disease and found linkage with several markers from chromosome 1p21. The Albers-Schönberg gene is located in a candidate region of approximately 8.5 cM flanked by markers D1S486 and D1S2792. A maximum LOD score (Z(max)) of 4.09 was obtained in multipoint analysis at loci D1S239/D1S248. Possible linkage of osteopetrosis to this chromosomal region was analyzed because the CSF-1 gene, which is mutated in the op/op mouse model for osteopetrosis, is located in 1p21. However, SSCP and mutation analysis in patients did not reveal any abnormality, which excludes the CSF-1 gene as the disease-causing gene. This was confirmed by refined physical mapping of the CSF-1 gene outside the candidate region for the Albers-Schönberg gene. The identification of the molecular defect underlying Albers-Schönberg disease will therefore be dependent on the isolation of other genes from an 8.5-cM candidate region on chromosome 1p21.

Colony stimulating factor-1 in human follicular fluid

OBJECTIVE

To evaluate colony stimulating factor-1 (CSF-1) concentrations in serum and follicular fluid (FF) at the time of oocyte retrieval and to test for presence of messenger RNA (mRNA) for CSF-1 and its receptor, c-fms, in FF cells.

DESIGN

Collection of serum and FF at the time of oocyte retrieval.

SETTING

A university IVF program.

PATIENT(S)

Forty-five women undergoing oocyte retrieval for IVF.

INTERVENTION(S)

Serum and FF were obtained from 24 women, and FF only was obtained from 21 women.

MAIN OUTCOME MEASURE(S)

Colony-stimulating factor-1 concentrations were determined by RIA, and the presence of mRNA for CSF-1 and c-fms was determined by reverse transcriptase-polymerase chain reaction.

RESULT(S)

Mean FF concentrations of CSF-1 were significantly higher than mean serum levels (10.0 +/- 1.3 and 3.6 +/- 0.3 (+/-SE) ng/mL, respectively). Colony-stimulating factor-1 and c-fms message were detected in FF cells, and alternatively spliced forms of CSF-1 message were present.

CONCLUSION(S)

The presence of CSF-1, a primary regulator of tissue macrophages, in FF, and the presence of mRNA for CSF-1 and its receptor c-fms in FF-derived cells, suggest a role for this growth factor in ovarian function.

Control of vascular smooth-muscle cell growth by macrophage-colony-stimulating factor

Since in several vascular diseases abnormal vascular smooth-muscle cell (VSMC) proliferation is often associated with the presence of macrophages, we examined whether macrophage-colony-stimulating factor (M-CSF) might play a role in the control of VSMC growth. VSMCs were isolated from rat aorta and maintained in culture. Using a bioassay, a macrophage-colony-stimulating activity was detected in the serum-free supernatant of VSMCs, which could be inhibited by the addition of specific anti-M-CSF antibodies. The presence of M-CSF receptor protein and of M-CSF and M-CSF receptor gene transcripts was demonstrated by immunocytochemistry, using a specific anti-c-Fms antibody and Northern blot analysis respectively. [3H]Thymidine incorporation was measured following the addition to quiescent VSMCs of various dilutions of L929 cell supernatant (as a source of M-CSF) or of recombinant M-CSF. Both exogenous M-CSF and serum-free VSMC conditioned medium promoted DNA synthesis in a concentration-dependent manner, and this effect could be abrogated by the presence of a specific anti-M-CSF antibody. Under similar experimental conditions, L929 cell supernatant modulated proto-oncogene expression, as assessed by Northern blot analysis of c-fos, c-myc, egr-1 and junB. It was further demonstrated that M-CSF could act in synergy with thrombin, platelet-derived growth factor or basic fibroblast growth factor in promoting VSMC DNA synthesis. These results support the hypothesis that M-CSF affects the growth of cultured rat VSMCs through paracrine/autocrine mechanisms. Its effects at both the macrophage and the VSMC level confer to M-CSF a central role in the development of vascular lesions that occurs during atherosclerotic progression.

Binding sites for adeno-associated virus Rep proteins within the human genome

The Rep proteins of adeno-associated virus type 2 (AAV) are known to bind to Rep recognition sequences (RRSs) in the AAV inverted terminal repeats (ITRs), the AAV p5 promoter, and the preferred AAV integration site in human chromosome 19, called AAVS1. Integration of the AAV genome into AAVS1 appears to be mediated by an interaction between the Rep proteins of AAV and Rep binding sites within the viral genome and the integration locus. In an attempt to identify potential alternate integration sites, we looked for recognition sites for AAV Rep proteins in the human genome by performing a BLASTN computerized homology search. We used the 16-mer core sequences of the RRSs in the AAV ITRs and AAVS1 separately as query sequences and identified 18 new RRSs in or flanking the genes coding for the following: tyrosine kinase activator protein 1 (TKA-1); colony stimulating factor-1; insulin-like growth factor binding protein 2 (IGFBP-2); histone H2B.1; basement membrane heparan sulfate proteoglycan, also known as perlecan; the AF-9 gene product, which is involved in the chromosomal translocation t (9:11)(p22:q23); the betaB subunit of the hormone known as inhibin; interleukin-2 enhancer binding factor; an endoplasmic reticulum-Golgi intermediate compartment resident protein called p63; a global transcription activator (hSNF2L); the beta-actin repair domain; a retinoic acid-inducible factor, also known as midkine; a breast tumor autoantigen; a growth-arrest- and DNA-damage-inducible protein called gadd45; the cyclin-dependent kinase inhibitor called KIP2, which inhibits several G1 cyclin-cyclin-dependent kinase complexes; and the hereditary breast and ovarian cancer gene (BRCA1). RRSs were also identified in a newly discovered open reading frame on chromosome 10 and in the ERCC1 locus on human chromosome 19. The ability of a maltose binding protein-Rep68 fusion protein to bind to these sequences was confirmed by electrophoretic mobility shift assays. These sites may serve as alternate integration sites for AAV or play a role in Rep-mediated effects on human cells.

Modulation of c-fms proto-oncogene in an ovarian carcinoma cell line by a hammerhead ribozyme

Co-expression of macrophage colony-stimulating factor (M-CSF) and its receptor (c-fms) is often found in ovarian epithelial carcinoma, suggesting the existence of autocrine regulation of cell growth by M-CSF. To block this autocrine loop, we have developed hammerhead ribozymes against c-fms mRNA. As target sites of the ribozyme, we chose the GUC sequence in codon 18 and codon 27 of c-fms mRNA. Two kinds of ribozymes were able to cleave an artificial c-fms RNA substrate in a cell-free system, although the ribozyme against codon 18 was much more efficient than that against codon 27. We next constructed an expression vector carrying a ribozyme sequence that targeted the GUC sequence in codon 18 of c-fms mRNA. It was introduced into TYK-nu cells that expressed M-CSF and its receptor. Its transfectant showed a reduced growth potential. The expression levels of c-fms protein and mRNA in the transfectant were clearly decreased with the expression of ribozyme RNA compared with that of an untransfected control or a transfectant with the vector without the ribozyme sequence. These results suggest that the ribozyme against GUC in codon 18 of c-fms mRNA is a promising tool for blocking the autocrine loop of M-CSF in ovarian epithelial carcinoma.

Structural requirements for the ectodomain cleavage of human cell surface macrophage colony-stimulating factor

One form of human macrophage colony-stimulating factor (CSF-1(256), M-CSFalpha) is a member of a restricted set of cell surface transmembrane proteins, which is selected to undergo proteolytic ectodomain cleavage. To determine the substrate requirements for this cleavage, we have constructed a series of mutations in the cytoplasmic tail, transmembrane domain, and juxtamembrane region of CSF-1(256) and stably expressed the mutated genes in NIH 3T3 cells. Our results demonstrate that membrane association of the CSF-1 precursor is required for cleavage of its growth factor ectodomain and furthermore that the juxtamembrane region Pro161-Gln162-Leu163-Gln164-Glu165 (PQLQE) (residues 161-165 of the ectodomain) is an essential determinant of cell surface CSF-1(256) cleavage and that the cleavage site is partially sequence-specific. Furthermore, a mechanism of steric hindrance, which likely involves interference with protease accessibility, is postulated to explain the observed decreases in the cleavage efficiency in certain CSF-1 mutants. Finally, our results strongly suggest that the CSF-1 ectodomain is cleaved at or very near the cell surface by a membrane-associated proteolytic system.

Colony-stimulating factors and coxackievirus B3 myocarditis in mice: macrophage colony-stimulating factor suppresses acute myocarditis with increasing interferon-alpha

The effects of macrophage colony-stimulating factor (M-CSF) and granulocyte colony-stimulating factor (G-CSF) on murine coxsackievirus B3 myocarditis were investigated. A total of 4 x 10(6) U/kg/day M-CSF and 20 micrograms/kg/day G-CSF were injected subcutaneously every day on day 0 to day 14 starting simultaneously with virus inoculation. Serum interferon-alpha was measured periodically. The survival rate of the M-CSF group was higher than that of the untreated control group (p < 0.05). On days 7 and 14 cardiac disease was significantly lower in the M-CSF group than in the untreated control group. Myocardial virus titers on day 7 in the M-CSF group were lower compared with those of the untreated control group. No significant difference was seen in the survival, cardiac disease, or myocardial virus titers between the G-CSF and the control groups. Monocyte counts on days 7 and 14 in the M-CSF group were increased compared with those in the control group. Serum interferon-alpha titers in the M-CSF and G-CSF groups on day 4 and those in the M-CSF group on day 7 were significantly increased in comparison with those of the untreated control group. We conclude that M-CSF but not G-CSF has the potency to limit myocardial virus titers and to reduce cardiac disease in the acute coxsackievirus B3 myocarditis. This ability is associated with an elevated interferon-alpha. Thus macrophages may play a defensive role in this model.

Efficacy of recombinant human granulocyte colony-stimulating factor and recombinant human granulocyte-macrophage colony-stimulating factor in neutropenic children with malignancies

The difference between the effects of administration of recombinant human granulocyte colony-stimulating factor (rhG-CSF) and recombinant human granulocyte-macrophage colony-stimulating factor (rhGM-CSF) was studied in 39 children with neutropenia secondary to chemotherapy (absolute neutrophil count (ANC) less than 1,500/microliters. The children were divided into two groups. The first group (G-CSF) included 25 children (12 with acute lymphoblastic leukemia [ALL]-non-Hodgkin's lymphoma [NHL] and 13 with solid tumors) and the second group (GM-CSF) included 14 children (5 with ALL-NHL and 9 with solid tumors). All 39 children received of either G-CSF or GM-CSF (5 micrograms/kg/day) subcutaneously at the end of each chemotherapy course for a maximum duration of 14 days. The effect of G-CSF and GM-CSF on the ANC, the antibiotic therapy administration, and the length of hospital stay were studied for both groups at two cycles of chemotherapy. During both cycles a faster rise of ANC was observed in the children of the first group (G-CSF) compared with those of the second group (GM-CSF), but there was no difference in either the incidence of antibiotic therapy administration between the two groups (26% vs 25%) or the length of hospitalization. Both growth factors were well tolerated by all children studied with minimal side effects observed (including bone pain with G-CSF in 2 of 25 children and pruritus with GM-CSF in 1 of 14). We conclude that G-CSF reduces the duration of neutropenia more than does GM-CSF, but the incidence of severe infection and the duration of hospitalization do not differ between children receiving either G-CSF or GM-CSF.

Transcriptional activation of the macrophage-colony stimulating factor gene by minimally modified LDL. Involvement of nuclear factor-kappa B

Minimally modified LDL (MM-LDL), obtained by mild iron oxidation or prolonged storage at 4 degrees C, has been shown to induce the expression of macrophage-colony stimulating factor (M-CSF) in cultured aortic endothelial cells. To examine whether other cell types also respond to MM-LDL, we investigated its effect on the expression of M-CSF mRNA in mouse L-cells and human aortic smooth muscle cells. Both L-cells and human aortic smooth muscle cells showed increased levels of M-CSF mRNA in response to 10 to 200 micrograms/mL MM-LDL in a dose-dependent manner. This allowed us to use mouse L-cells as a model to study the mechanism involved in MM-LDL-mediated increase in M-CSF mRNA. Nuclear runon assays showed that M-CSF gene transcription was activated by MM-LDL. In the present study, we identified specific elements that conferred MM-LDL-mediated transcriptional activation of the human M-CSF gene. Chimeric constructs containing sequential deletions in the 5'-promoter region of the M-CSF gene linked to a reporter chloramphenicol acetyltransferase (CAT) gene were transfected into mouse L-cells. The human M-CSF promoter region extending upstream from the transcription start site to nucleotide -406 showed maximum induction of CAT activity by MM-LDL. Induction of CAT activity was drastically reduced, with a deletion plasmid lacking the promoter region -406 to -344. A functional nuclear factor (NF)-kappa B binding site present in this critical region was required for MM-LDL-mediated induction of CAT activity since an internal deletion construct lacking this element showed significant loss of transcriptional activation.(ABSTRACT TRUNCATED AT 250 WORDS)

Novel insights into the biology and physiology of the Ito cell

Ito cells, perisinusoidal mesenchymal elements with possible pericytic functions within the liver, recently have been shown to play multiple physiological and pathophysiological roles. In particular, several in vivo and in vitro studies have clearly indicated that Ito cells play a relevant role in the progression of liver fibrogenesis. More recently, attention has been focussed on the mechanisms leading to Ito cell activation, proliferation and synthesis of extracellular matrix components. Among other soluble factors potentially involved in these processes, transforming growth factor-beta 1 and platelet-derived growth factor have been shown to act in a paracrine, and possibly autocrine, fashion on Ito cells, thus perpetuating their activated state. Finally, other studies have shown that Ito cells could play an active role in chronic liver tissue inflammation by promoting chemotaxis of infiltrating inflammatory cells.

Is the osteopetrotic (op/op mutant) mouse completely deficient in expression of macrophage colony-stimulating factor?

The op/op mouse has a mutation in the macrophage colony-stimulating (CSF-1) gene. The phenotype of gross deficiency in the macrophage and osteoclast lineages corrects significantly with age, suggesting that other factors can substitute for CSF-1. This review examines the evidence that the op/op mouse is completely CSF-1 deficient and considers the possibility that alternative splicing within the CSF-1 gene might bypass the mutation, yielding an incompletely penetrant phenotype.

The international standard for macrophage colony stimulating factor (M-CSF). Evaluation in an international collaborative study

Three ampouled preparations of macrophage colony stimulating factor (M-CSF) were evaluated by 23 laboratories in nine countries for their suitability to serve as international standards for this material. The preparations were assayed in a wide range of in vitro bioassays and immunoassays. On the basis of results reported here, with the agreement of the participants in the study and with the authorization of the Expert Committee on Biological Standardization (ECBS) of the World Health Organization (WHO), the preparation in ampoules coded 89/512 was established as the international standard for M-CSF.

Development and maturation of neutrophils

Inflammatory processes require the activation of immunocompetent cells. In mammals, neutrophil polymorphonuclear leukocytes (PMN) constitute one of the essential body defences against diseases. In this article knowledge of the development and maturation of neutrophils, the control of haematopoiesis and of the factors that regulate neutrophil production is reviewed. As it has recently become apparent that neutrophils can be primed by cytokines to have enhanced functional activity, the future utilization of these growth factors in bovine immunotherapy is briefly discussed.

Unique dermatological complication of rhM-CSF treatment

A patient is presented who developed cutaneous papular histiocytic infiltrates after treatment with monocyte colony stimulating factor (rhM-CSF). This is the first reported complication of this type after treatment with this new cytokine.

Serum levels of macrophage colony stimulating factor (M-CSF) in liver disease

We investigated the serum level of macrophage colony stimulating factor in acute and chronic liver disease. Levels of macrophage colony stimulating factor (mean +/- SD, ng/ml) were significantly higher in acute hepatitis (5.67 +/- 1.01, p < 0.01) and chronic active hepatitis (3.34 +/- 1.19, p < 0.01) than in healthy volunteers (1.90 +/- 0.25), asymptomatic hepatitis B virus carriers (1.98 +/- 0.40), and chronic persistent hepatitis (2.34 +/- 0.43). Levels of macrophage colony stimulating factor showed a highly significant correlation with the serum alanine aminotransferase levels in acute hepatitis (p < 0.01, rs = 0.903) and in chronic active hepatis (p < 0.01, rs = 0.672). Levels of macrophage colony stimulating factor in patients with cirrhosis (cirrhosis; 3.11 +/- 0.93 and hepatocellular carcinoma; 3.30 +/- 0.74) were significantly higher than in patients with chronic persistent hepatitis although the alanine aminotransferase levels were not significantly different. In cirrhosis, levels of macrophage colony stimulating factor correlated positively with the serum alanine aminotransferase levels (p < 0.05), total bilirubin levels (p < 0.05), and indocyanine green clearance (p < 0.05). An immunohistochemical study showed an increased number of macrophage colony stimulating factor positive mononuclear cells in portal areas in acute hepatitis. Our findings suggest that; (a) the serum levels of macrophage colony stimulating factor represent ongoing hepatocellular necrosis in acute and chronic liver disease, (b) the source of the increase in the serum macrophage colony stimulating factor levels in hepatic inflammation may be, in part, its production by infiltrating mononuclear cells in the liver, and (c) cirrhosis also causes elevated serum levels of macrophage colony stimulating factor.

Depletion of manganese within the secretory pathway inhibits O-linked glycosylation in mammalian cells

Proteins transiting the secretory pathway are posttranslationally modified by addition of oligosaccharides to asparagine N-linked and serine and threonine O-linked residues. The effects of divalent cation depletion on oligosaccharide processing of erythropoietin (EPO) and macrophage colony stimulating factor (M-CSF) were studied in Chinese hamster ovary cells. Treatment with A23187 did not inhibit M-CSF or EPO secretion but did inhibit addition of complex N-linked and O-linked oligosaccharides to both molecules. Similar results were obtained by treatment with thapsigargin, a potent inhibitor of the Ca(2+)-activated microsomal ATPase, indicating that the effect was due to depletion of divalent cations within the secretory pathway. Whereas addition of extracellular calcium chloride did not reverse the inhibition in complex N-linked and O-linked glycosylation, addition of manganese chloride partially reversed both defects. These results are consistent with a specific manganese requirement within the secretory pathway for the processing of complex N-linked oligosaccharides and the addition of O-linked oligosaccharides. Since there are no known specific inhibitors of O-linked glycosylation, the use of ionophores should significantly facilitate studies on the requirement and role of O-linked oligosaccharides in protein structure and function.

Quantitative analysis of the two macrophage colony-stimulating factor mRNA expressed in a human stromal cell line by reverse transcription-polymerase chain reaction (RT-PCR)

We established a quantitative analysis system for 4.0 kb and 1.6 kb macrophage colony-stimulating factor (M-CSF) mRNA, using reverse transcription-polymerase chain reaction. Using this system, we performed quantitative analysis of the two mRNAs expressed in the human stromal cell line, KM102, in the resting condition and when stimulated by various concentrations of interferon-gamma (IFN-gamma). The expression of 1.6 kb M-CSF mRNA was more efficiently stimulated by IFN-gamma than that of 4.0 kb M-CSF mRNA. The alternative splicing of a single M-CSF gene has been shown to generate several M-CSF proteins with different localization; we believe that molecular analysis of the transcription products by this system is important to better understand the physiological significance of the different species of M-CSF derived from each mRNA.

Expression of biologically active monomeric form of human M-CSF in baculovirus infected silkworm, Bombyx mori

The human macrophage colony stimulating factor (hM-CSF) in its monomeric form has been over-produced in BmN cells and in silkworm larvae infected with the recombinant baculovirus Bm284M-CSF. The recombinant monomeric M-CSF (rhM-CSF) exhibited the activity of 8-14 x 10(4) units/ml of cell culture medium. When the insect larvae were infected with the recombinant virus, the maximum rhM-CSF was expressed 4-5 days post infection with an activity of 3 x 10(6) units/ml hemolymph. The monomeric rhM-CSF was purified to homogeneity through three steps of purification. A pilot purification yielded 1 mg of homogeneous monomeric rhM-CSF from 10 larvae. The purified rhM-CSF monomers gradually dimerized in vitro. In contrast, the crude or the semi-purified monomers did not dimerize in vitro, indicating that the presence of an unknown moiety in the rhM-CSF preparations obtained from hemolymph interfered with dimerization.

Two novel colony-stimulating factor 1 (CSF-1) properties: it post-transcriptionally inhibits interferon-specific induction of class II antigens and reduces the risk of fetal abortion

Local production of 250 U/ml of Colony Stimulating Factor 1 (CSF-1) by decidual cells on the 11th day of murine pregnancy prompted us to investigate the role of this mononuclear phagocyte factor during gestation. We show that the presence of CSF-1 accounts for down-regulating induction of class II antigens on the placenta, antigens whose presence leads to fetal death. It is known from previous studies that gamma interferon (IFN-gamma) induces the expression of MHC-Ia antigens on the placenta causing thus fetal rejection due to an immune reaction the mother develops against the fetus. This Ia induction occurs both in vitro and in vivo, however, an extra dose of CSF-1, in addition to the physiological levels already present, overwhelms the ability of IFN-gamma to such induction and the embryos are rescued. Thus, CSF-1 appears to be an inhibitor of IFN-gamma induced class II expression, a property that may permit CSF-1 to be employed during gestation to safeguard the outcome of pregnancy and alleviate, by extrapolation to the human system, the recurrent abortion issue. This action, however, is not unique during gestation only. Other inducible IFN-gamma cells (WEHI-3, HL-60 and HeLa) are also blocked by CSF-1 not to express surface class II antigens, as it has been recently reported on glia cells. At the mRNA level, however, CSF-1 is unable to block class II induction, a finding that suggests a post-transcriptional regulation pattern.

Structural comparisons among the short-chain helical cytokines

BACKGROUND

Cytokines and growth factors are soluble proteins that regulate the development and activities of many cell types. One group of these proteins have structures based on a four-helix bundle, though this similarity is not apparent from amino acid sequence comparisons. An understanding of how diverse sequences can adopt the same fold would be useful for recognizing and aligning distant homologs and for applying structural information gained from one protein to other sequences.

RESULTS

We have approached this problem by comparing the five known structures which adopt a granulocyte-macrophage colony-stimulating factor (GM-CSF)-like, or short-chain fold: interleukin (IL)-4, GM-CSF, IL-2, IL-5, and macrophage colony-stimulating factor. The comparison reveals a common structural framework of five segments including 31 inner-core and 30 largely exposed residues. Buried polar interactions found in each protein illustrate how complementary substitutions maintain protein stability and may help specify unique core packing. A profile based on the known structures is not sufficient to guarantee accurate amino acid sequence alignments with other family members. Comparisons of the conserved short-chain framework with growth hormone define the optimal structural alignment.

CONCLUSIONS

Our results are useful for extrapolating functional results among the short-chain cytokines and growth hormone, and provide a foundation for similar characterization of other subfamilies. These results also show that the placement of polar residues at different buried positions in each protein complicates sequence comparisons, and they document a challenging test case for methods aimed at recognizing and aligning distant homologs.

Levels of serum colony-stimulating factors (CSFs) in patients on long-term haemodialysis

We measured the levels of colony-stimulating factors (G-CSF, M-CSF and GM-CSF) and several cytokines in paired sera obtained from 51 patients (33 males and 18 females; mean age: 53 years) on long-term haemodialysis (HD). The mean pre-HD G-CSF level was 22.7 +/- 21.7 pg/ml and the post-HD level was 40.3 +/- 54.4 pg/ml. The mean pre-HD M-CSF level was 2.4 times higher than normal at 1287 +/- 380 U/ml, and it increased to 1644 +/- 456 U/ml after HD (r = 0.83). GM-CSF was not detectable in any of the serum samples. IL-1 beta was detectable in 38 pre-HD sera at a mean level of 57.1 +/- 21.8 pg/ml, but was rarely detected after HD. TNF-alpha was not usually detected. When the CSF levels were divided by the product of the serum total protein concentration and body weight, the post-HD value for G-CSF was almost always greater than the pre-HD value and there was an improved pre-post correlation (r = 0.69). In the transformed pairs of M-CSF level, the post-HD value did not differ much from the pre-HD value, and a strong pre-post correlation was noted (r = 0.94). These results suggest that the serum G-CSF level is not affected by chronic renal failure, although HD may induce an increase of G-CSF. In the case of M-CSF, however, impaired renal metabolism and/or excretion may increase the serum concentration, but it is not modulated by haemodialysis.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of granulocyte colony-stimulating factor on chemotherapy-induced neutropenia in children with cancer

We investigated the effects of recombinant granulocyte colony-stimulating factor (G-CSF) administration on duration of neutropenia, antibiotic therapy, and hospitalization days in 25 children with malignancies (Group A: 12 leukemia and lymphoma; Group B: 13 tumors) who were undergoing chemotherapy. We compared the effect of G-CSF with a control group of 21 children with equivalent diseases and chemotherapy that did not receive G-CSF treatment. All 25 children received 5 micrograms/kg/day of G-CSF at the end of chemotherapy courses when absolute neutrophil counts were < or = 1000/mm3. The effect of G-CSF on median neutrophil profiles, antibiotic therapy, and hospitalization days was studied for both groups at the 1st and 4th cycle of chemotherapy. During both cycles, children who received G-CSF showed a faster rise of absolute neutrophil count (P < 0.001) and fewer hospitalization days (P < 0.05), and not as many received systemic antibiotic therapy (P < 0.0001). We conclude that G-CSF accelerates neutrophil recovery in chemotherapy-induced neutropenia in childhood malignancies.

Differential regulation of M-CSF and IL-6 gene expression in monocytic cells

Using the human monocytic cell line Mono Mac 6 we studied the involvement of Ca2+, protein kinase A (PKA), and protein kinase C (PKC) dependent pathways in the regulation of M-CSF and IL-6 gene expression. The results demonstrate that on activation with the calcium ionophore A23187 both M-CSF and IL-6 mRNA are induced after 3 and 6 h respectively. Co-stimulation with A23187 plus PMA resulted in an up-regulation of M-CSF mRNA and a down-regulation of IL-6 mRNA. Conversely co-stimulation with A23187 plus DBcAMP resulted in a down-regulation of M-CSF mRNA and an up-regulation of IL-6 mRNA. Nuclear run-on and mRNA half-life studies showed that the effects on the M-CSF expression were related to changes at transcriptional and post-transcriptional level. In contrast, the effects on the IL-6 gene expression seems to be mediated at post-transcriptional level. With regard to the secretion of the IL-6 protein it was shown that it closely follows the accumulation of IL-6 mRNA. Taken together, the data show that several intracellular signalling pathways control strictly the cytokine expression in monocytic cells which gives the cells the opportunity to respond variably to external activation signals.

Basal expression of the human macrophage colony-stimulating factor (M-CSF) gene in K562 cells

Macrophage colony-stimulating factor (M-CSF) functions in hematopoiesis and regulates mature monocytes. Untreated K562 leukemic cells transcribe M-CSF. Elements between bases -43 and -77 (NF-KB enhancer) and between -129 and -180 (Sp1 enhancer) of the M-CSF promoter were important for basal transcription. Gel Shift assays and ultraviolet crosslinking experiments showed a 50 kDa protein bound to the NF-KB element at -65 in a GTP-dependent fashion. Additionally, a K562 nuclear protein, specifically bound the Sp1 enhancer. Run-off transcription and half-life studies showed that M-CSF is regulated primarily at the post-transcriptional level.

Colony stimulating factor-1 expression in human glioma

Colony stimulating factor 1 (CSF-1) is a functionally versatile, circulating homodimeric growth factor that stimulates the survival, proliferation, and differentiation of mononuclear phagocytic cells, the differentiation of osteoclast progenitor cells and that regulates cells of the female reproductive tract. CSF-1 is also expressed in the central nervous system where it may regulate the differentiation and activation of microglia. The diverse forms of CSF-1 are all encoded by a single gene. Alternative posttranscriptional splicing and posttranslational cleavage determines whether CSF-1 will be produced as a secreted proteoglycan, secreted glycoprotein, or as a cell-surface glycoprotein that may be involved in cell-cell interactions. CSF-1 is expressed in glioblastoma cell-lines, normal human astrocytes, and in operative specimens of human glioma. The CSF-1 receptor, encoded by the c-fms proto-oncogene, is also expressed in human gliomas. We conclude that coexpression of CSF-1 and its receptor in some human gliomas hints at a possible autocrine or paracrine growth stimulatory role for CSF-1; however, its function in the mammalian CNS remains to be elucidated.

Constitutive production of multiple colony-stimulating factors in patients with lung cancer associated with neutrophilia

Production of colony-stimulating factor (CSF) was examined in three patients with lung cancer associated with neutrophilia. All three patients presented a marked increase in neutrophil count (26,000-39,000 microliters-1) that continued at least for 3 weeks and rapidly disappeared after surgical removal of the tumours. Culture media (CM) incubated with the excised tumour tissues stimulated the colony formation of bone marrow myeloid progenitor cells in vitro. Northern blot analysis of poly(A)+ RNA from the tumour tissues revealed a constitutive expression of granulocyte (G), macrophage (M), and granulocyte-macrophage (GM) CSF genes in all tumours. Immunoassay specific for these CSFs revealed that G- and M-CSF immunoreactivity was detected in all CM and GM-CSF protein in two out of three CM. The plasma CSF levels also increased before operation and decreased to normal or near-normal range after operation. In contrast, tumour cell CM obtained from two lung cancer patients without leucocytosis neither stimulated haematopoietic colony formation nor contained immunoreactive CSFs. These results indicated that the neutrophilia found in the three patients was probably caused by constitutive production of multiple CSFs by lung cancer cells.

High titre anticytokine antibodies obtained by intralymphnode immunization with low amounts of antigen

Intralymphnode immunization was performed on rabbits to obtain anticytokine antibodies using low or very low amounts of the following purified cytokines: CSF-1 (or M-CSF: 10, 2 or 0.2 microgram/injection), GM-CSF (10 micrograms/injection), IL-2 (10 micrograms/injection) and HILDA/LIF (10 micrograms for the first injection and 5 micrograms/injection for boosts). This technique is easily performed by dissection of the popliteal lymphnode. Specific high titre antibodies were obtained after the first or second boost for antigen doses between 10 (for all cytokines tested) and 0.2 microgram (for CSF-1) per injection. In most cases, these antibodies could be used for immunoprecipitation, competition assays, dot immunoblotting, neutralization of biological activity and receptor binding inhibition. Some applications show that these tools are useful for cytokine research projects. For newly identified cytokines available in limited amounts, this method of obtaining specific polyclonal antibodies is an interesting alternative to the expensive, time-consuming and technically more demanding monoclonal antibody method.

The v-sis protein retains biological activity as a type II membrane protein when anchored by various signal-anchor domains, including the hydrophobic domain of the bovine papilloma virus E5 oncoprotein

Membrane-anchored forms of the v-sis oncoprotein have been previously described which are oriented as type I transmembrane proteins and which efficiently induce autocrine transformation. Several examples of naturally occurring membrane-anchored growth factors have been identified, but all exhibit a type I orientation. In this work, we wished to construct and characterize membrane-anchored growth factors with a type II orientation. These experiments were designed to determine whether type II membrane-anchored growth factors would in fact exhibit biological activity. Additionally, we wished to determine whether the hydrophobic domain of the E5 oncoprotein of bovine papilloma virus (BPV) can function as a signal-anchor domain to direct type II membrane insertion. Type II derivatives of the v-sis oncoprotein were constructed, with the NH2 terminus intracellular and the COOH terminus extracellular, by substituting the NH2 terminal signal sequence with the signal-anchor domain of a known type II membrane protein. The signal-anchor domains of neuraminidase (NA), asialoglycoprotein receptor (ASGPR) and transferrin receptor (TR) all yielded biologically active type II derivatives of the v-sis oncoprotein. Although transforming all of the type II signal/anchor-sis proteins exhibited a very short half-life. The short half-life exhibited by the signal/anchor-sis constructs suggests that, in some cases, cellular transformation may result from the synthesis of growth factors so labile that they activate undetectable autocrine loops. The E5 oncoprotein encoded by BPV exhibits amino acid sequence similarity with PDGF, activates the PDGF beta-receptor, and thus resembles a miniature membrane-anchored growth factor with a putative type II orientation. The hydrophobic domain of the E5 oncoprotein, when substituted in place of the signal sequence of v-sis, was indistinguishable compared with the signal-anchor domains of NA, TR, and ASGPR, demonstrating its ability to function as a signal-anchor domain. NIH 3T3 cells transformed by the signal/anchor-sis constructs exhibited morphological reversion upon treatment with suramin, indicating a requirement for ligand/receptor interactions in a suramin-sensitive compartment, most likely the cell surface. In contrast, NIH 3T3 cells transformed by the E5 oncoprotein did not exhibit morphological reversion in response to suramin.

Chicken repeat 1 elements contain a pol-like open reading frame and belong to the non-long terminal repeat class of retrotransposons

Chicken genomes contain approximately 30,000 chicken repeat 1 (CR1) elements scattered among single-copy sequences, but no information has yet been presented to account for how these elements could have dispersed. The fact that CR1 elements have common (although atypical) 3' ends and variable 5' truncations suggested to us that they might belong to the class of non-long terminal repeat retrotransposons that encode reverse transcriptases. From an analysis of unusually large CR1 elements, we now provide evidence for the presence of such a reverse transcriptase open reading frame. CR1 elements are distantly related to previously described non-long terminal repeat retrotransposons; however, we find that frog and torpedo ray genomes contain dispersed open reading frame segments that have > 50% identity to the CR1 open reading frame. This result suggests that CR1-like elements exist in several vertebrate classes that have evolved independently for approximately 400 million years.

Isolation and characterization of a cDNA clone encoding for rat CSF-1 gene. Post-transcriptional repression occurs in myogenic differentiation

A major CSF-1 (Colony-Stimulating Factor 1) mRNA 4.0 kb long was expressed during the proliferation of the L6 alpha 1 rat myogenic cells and was down-regulated after their differentiation into myotubes. A complete cDNA encoding the rat CSF-1 gene (rmCSF-1) was isolated from a cDNA library of L6 alpha 1 myoblasts and sequenced. The overall deduced amino acid sequence was 100% and 68% identical to the mouse and human CSF-1, respectively. While the previously reported mechanisms about the regulation of CSF-1 expression in TPA-treated-monocytes (Horiguchi, J., Sariban, E. and Kufe, D. (1988) Mol. Cell. Biol. 8, 3951-3954) and in fibroblasts (Falkenburg, J.H.F., Harrington, M.A., De Paus, R.A., Walsh, M.K., Daub, R., Landegent, J.E. and Broxmeyer, H.E. (1991) Blood 78, 658-665) involved a control at the transcriptional level, in contrast, the CSF-1 mRNA (half-life approximately 3 h in L6 alpha 1 myoblasts) was post-transcriptionally down-regulated during myogenesis. Inhibition of protein synthesis with cycloheximide (CHX) increased differentially the half-life of CSF-1 mRNA in L6 alpha 1 myotubes compared to L6 alpha 1 myoblasts. Finally, L6 alpha 1 myoblasts were shown to synthesize a 140 kDa homodimeric form of CSF-1. Thus, these findings, together with other results, indicate that CSF-1 gene products may play a role in the normal and neoplastic proliferation of muscular cells.

Regulation of the macrophage population in postnatal rat testis

Testicular macrophages increase in concentration during postnatal development in rats. This process may be under hormonal control since administration of hCG stimulates a similar increase to occur precociously. The purpose of the present studies was to determine how the macrophage population is regulated during normal postnatal development and in response to exogenous hCG. We first determined that testicular macrophages proliferate in situ during development and that hCG administration results in an increase in proliferation when given to 10-day-old rats. We next evaluated whether hCG might exert its effects through enhanced secretion of testosterone from Leydig cells. We found that testosterone could not induce a precocious increment in the macrophage concentration when it was administered to newborn pups for 10 days. Finally, the normal increase in macrophage concentration that occurs prior to puberty could not be blocked by treatment with the antiandrogen Casodex. The results are consistent with the hypothesis that the macrophage population expands by proliferation, perhaps under gonadotropin control. In addition, neither the precocial expansion that occurs in response to hCG nor the normal expansion that occurs before puberty is mediated by testosterone.

Degradation pathways for recombinant human macrophage colony-stimulating factor in aqueous solution

Recombinant human macrophage colony-stimulating factor (rhM-CSF) promotes macrophage proliferation and activity. rhM-CSF clinical trials are currently in progress and require a stable, pharmaceutically acceptable dosage form. This report documents pH effects on rhM-CSF degradation profiles in aqueous solution, with an emphasis on identifying degradation products. Thus, highly purified rhM-CSF was maintained at 30 to 50 degrees C in solutions adjusted to pH 2 to 10. Stressed samples were analyzed by SDS-PAGE, reverse-phase HPLC, size exclusion HPLC, scanning microcalorimetry, and murine bone marrow activity. The results show maximal protein stability in the region pH 7 to 8. Degradation product chromatographic and electrophoretic analyses show distinctly different degradation product profiles in acidic versus alkaline solution. For samples stressed in acidic solution, degradation products were isolated chromatographically and electrophoretically. These degradation products were characterized by N-terminal amino acid sequencing, fast-atom bombardment mass spectrometry, and peptide mapping. The results show that the major degradation pathway in acidic solution involves peptide cleavage at two sites: aspartate169-proline170 and aspartate213-proline214. A third potential cleavage site (aspartate45-proline46) remains intact under conditions that cleave Asp169-Pro170 and Asp213-Pro214. In alkaline solution, degradation proceeds via parallel cleavage and intramolecular cross-linking reactions. A beta-elimination mechanism is proposed to account for the degradation in alkaline solution. Consistent with literature observations, the rhM-CSF N-terminal cleavage products retain biological activity.

Human macrophage colony-stimulating factor levels in cerebrospinal fluid

Macrophage colony-stimulating factor (M-CSF) levels in the cerebrospinal fluid of 14 patients with meningitis and of 14 patients suffering from a disease other than meningitis were measured using an enzyme-linked immunosorbent assay. All four bacterial meningitis patients had M-CSF levels in the cerebrospinal fluid which exceeded 1540 U/ml, and the mean value was 3333 +/- 1481 U/ml. The mean M-CSF level in the cerebrospinal fluid of the ten aseptic meningitis patients was 393 +/- 175 U/ml, which was higher than that of patients who suffered from a disease other than meningitis (179 +/- 90 U/ml) (P < 0.01). There was no clear correlation between the M-CSF levels and the numbers of white blood cells, granulocytes, or monocytes in the cerebrospinal fluid. These elevated M-CSF levels were thought to be of a local origin, since most patients with high M-CSF levels in the cerebrospinal fluid had relatively low M-CSF levels in the serum.