Biomedical subjects

G J Atkins

Publications and source records attributed to G J Atkins.

At least 37 records · Page 2Linked to original sources

PubMed2001

Osteoprotegerin and receptor activator of nuclear factor kappaB ligand (RANKL) regulate osteoclast formation by cells in the human rheumatoid arthritic joint.

OBJECTIVE: This study investigated the involvement of the recently identified regulators of osteoclast formation RANKL [receptor activator of nuclear factor kappaB (RANK) ligand, osteoclast differentiation factor, TRANCE, osteoprotegerin ligand] and its natural inhibitor, osteoprotegerin (OPG), in the bone erosion of rheumatoid arthritis (RA). METHODS: mRNA was extracted from cells isolated from the pannus and synovial membrane regions of joints of 11 RA patients. Semiquantitative reverse transcription-polymerase chain reaction was carried out, and the isolated cells were also cultured to determine their ability to form osteoclasts. RESULTS: mRNAs encoding RANKL, RANK, OPG and macrophage-colony stimulating factor were expressed by cells isolated from RA joints. In addition, mRNA encoding for tumour necrosis factor apoptosis-inducing ligand and the osteoclast markers tartrate-resistant acid phosphatase and calcitonin receptor were also often expressed. Osteoclasts capable of forming resorption lacunae were generated from cells in the RA joints. At 50 ng/ml, recombinant OPG completely inhibited the resorptive activity of these cells. There was a significant correlation between the ratio of RANKL mRNA to OPG mRNA and the number of resorption pits produced (P = 0.028). CONCLUSION: These data suggest that RANKL is an essential factor for osteoclast formation by cells in the rheumatic joint and that OPG may prevent the bone erosion seen in RA joints.

Adult↗

PubMed2001

Altered p53 expression in benign and malignant skin lesions from renal transplant recipients and immunocompetent patients with skin cancer: correlation with human papillomaviruses?

Renal transplant recipients are prone to numerous benign and malignant skin lesions. Previous work in the authors' laboratory has determined that the human papillomavirus may be the viral aetiology of these skin lesions. The p53 tumor-suppressor gene is the most frequently mutated gene in a wide range of human cancers. Here the authors describe an immunohistochemical study to evaluate the expression of p53 in benign and malignant skin lesions from renal transplant recipients and immunocompetent patients with skin cancer. The effect of p53 mutations on the expression patterns observed were examined by polymerase chain reaction-single strand conformation polymorphism analysis and direct cycle sequencing. The expression of the p53-regulated cyclin-dependant kinase inhibitor p21Waf1/Cip1 and Mdm2 was also examined in p53-positive cells. The expression of p53 in benign and malignant lesions was found to be markedly different. p53 was expressed in only 40% (6/15) of viral warts analyzed. The expression was confined to the basal layer both in the lesion and in adjacent normal skin, and the level of expression was low and only in a small number of cells (<10%). Of the cutaneous squamous cell carcinomas analyzed, 60% (9/15) showed p53 expression. Two different patterns of expression were observed. Basal layer expression in both the invasive tumor and adjacent normal skin was observed in 50% of the p53-positive squamous cell carcinomas; in the remaining 50%, p53 was expressed diffusely throughout the invasive tumor and in the basal layer of adjacent normal skin. The level of expression was high and in a large number of cells. Polymerase chain reaction-single strand conformation polymorphism analysis revealed that only one of the squamous cell carcinomas expressing p53 harbored a p53 mutation and that the accumulated p53 in the remaining tumors was wild type. No Mdm2 or p21Waf1/Cip1 expression was detected in the p53-positive squamous cell carcinomas, indicating that although the accumulated p53 is stable, it does not function effectively as a transcriptional activator. This represents a novel p53 phenotype in cutaneous squamous cell carcinoma. In addition, no correlation was seen between the presence and absence of human papillomavirus and p53 expression.

Carcinoma, Squamous Cell↗

PubMed2001

p53 codon 72 polymorphism and human papillomavirus associated skin cancer.

BACKGROUND/AIMS: Non-melanoma skin cancers frequently harbour multiple human papillomavirus (HPV) types. A recent report suggests that a polymorphism of the p53 tumour suppressor gene that results in the substitution of a proline residue with an arginine residue at position 72 of the p53 protein might act as a risk factor in HPV associated malignancies. This study aimed to determine the following: (1) the relation between HPV infection and the development of cutaneous squamous cell carcinoma (SCC), and (2) whether there is a correlation between p53 codon 72 polymorphism and the development of SCC. METHODS: Blood samples were taken from 55 patients with skin cancer (both renal transplant recipients and immunocompetent patients with skin cancer) and 115 ethnically matched volunteers. A polymerase chain reaction based assay was used to determine p53 codon 72 genotypes. In addition, 49 benign and malignant lesions from 34 of the patients with skin cancer and 20 normal human skin samples from 20 of the control volunteers were examined for HPV. RESULTS: The proportions of p53 codon 72 genotypes found were 78% arginine homozygous, 2% proline homozygous, and 20% heterozygous among patients with skin cancer and 79% arginine homozygous, 3.5% proline homozygous, and 17.5% heterozygous among the control population. Statistical analysis showed no significant differences in the distribution of the two p53 isoforms between the patients with skin cancer and the control population. The predominant viral types detected in both the patients and the control group were EV associated HPVs, although the incidence was lower in normal skin samples than in malignant lesions or viral warts. CONCLUSIONS: These results suggest that in a Celtic population there is no correlation between the presence of HPV, the p53 codon 72 arginine polymorphism, and the development of skin cancer.

Carcinoma, Squamous Cell↗

PubMed2001

A high degree of chromosomal instability at 13q14 in cutaneous squamous cell carcinomas: indication for a role of a tumour suppressor gene other than Rb.

BACKGROUND/AIMS: Loss of function of the retinoblastoma (Rb) tumour suppressor gene, located on chromosome 13, is common in many inherited and sporadic forms of cancer. Inactivation of its gene product by oncogenic human papillomaviruses (HPV) plays a key role in the genesis of cervical cancer. It has been shown previously that non-melanoma skin cancers of renal transplant recipients and immunocompetent patients with skin cancer also frequently harbour potentially oncogenic HPV types. This study aimed to examine the integrity of the Rb gene in histologically confirmed squamous cell carcinomas (SCCs) from renal transplant recipients and immunocompetent patients with skin cancer. METHODS: Loss of heterozygosity (LOH) at the Rb locus was examined in 13 histologically confirmed SCCs using the D13S153 microsatellite marker, which is located in exon 2 of the Rb gene. Loss of a second marker, D13S118, distal telomerically to the Rb gene at 13q14.3 was also analysed. RESULTS: Of the 13 HPV associated SCCs examined 11 were informative (two SCCs were homozygous for both microsatellite markers). LOH at the D13S153 locus was found in four of the 10 informative SCCs and LOH at the D13S118 locus was found in five of the 11 informative cases. Overall, seven of the 11 informative cases showed LOH at one or other locus. This represents a high degree of chromosomal instability in these tumours. The expression of the Rb gene product in the 11 informative cases was analysed immunohistochemically. Expression of Rb was detected in 10 of the 11 SCCs examined. No correlation between the HPV status of the tumours and the expression of Rb was found. Although the only SCC not to express Rb also demonstrated LOH at the D13S153 locus, the remaining SCCs that had LOH at 13q14 were able to express RB: CONCLUSION: Another tumour suppressor gene located at 13q14 might be responsible for the genesis of these tumours.

Carcinoma, Squamous Cell↗

PubMed2001

Enhanced apoptosis of soft tissue sarcoma cells with chemotherapy: A potential new approach using TRAIL.

Soft tissue sarcomas are less responsive to conventional chemotherapy when compared to bone sarcomas. We investigated the possibility of enhancing the efficacy of chemotherapy by utilising the recently identified cytokine, tumour necrosis factor-related apoptosis-inducing ligand (TRAIL/Apo2L) in combination with standard chemotherapeutic agents. Fresh human soft tissue sarcomas (rhabdomyosarcoma, fibrosarcoma, malignant fibrous histiocytoma) were obtained at biopsy and dispersed tumour cells were incubated in cell culture with standard cytotoxic agents, either as single agents or in combination with TRAIL. The chemotherapeutic agents were, at best, moderately effective, in terms of induction of cellular apoptosis, although the fibrosarcoma was completely unresponsive to all single agents. TRAIL alone had no effect on any sarcoma cell culture. In contrast, the addition of TRAIL and drug together produced a significant increase in sarcoma cell apoptosis, with TRAIL and doxorubicin the most effective combination.

Journal Article↗

PubMed2001

The osteoclastogenic molecules RANKL and RANK are associated with periprosthetic osteolysis.

Extensive osteolysis adjacent to implants is often associated with wear particles of prosthetic material. We have investigated if RANKL, also known as osteoprotegerin ligand, osteoclast differentiation factor or TRANCE, and its natural inhibitor, osteoprotegerin (OPG), may be important in controlling this bone loss. Cells isolated from periprosthetic tissues containing wear particles expressed mRNA encoding for the pro-osteoclastogenic molecules, RANKL, its receptor RANK, monocyte colony-stimulating factor (M-CSF), interleukin (IL)-1beta, tumour necrosis factor (TNF)alpha, IL-6, and soluble IL-6 receptor, as well as OPG. Osteoclasts formed from cells isolated from periprosthetic tissues in the presence and absence of human osteoblastic cells. When osteoclasts formed in the absence of osteoblastic cells, markedly higher levels of RANKL mRNA relative to OPG mRNA were expressed. Particles of prosthetic materials also stimulated human monocytes to express osteoclastogenic molecules in vitro. Our results suggest that ingestion of prosthetic wear particles by macrophages results in expression of osteoclast-differentiating molecules and the stimulation of macrophage differentiation into osteoclasts.

Carrier Proteins↗

PubMed2001

The ratio of messenger RNA levels of receptor activator of nuclear factor kappaB ligand to osteoprotegerin correlates with bone remodeling indices in normal human cancellous bone but not in osteoarthritis.

The determinants of cancellous bone turnover and trabecular structure are not understood in normal bone or skeletal disease. Bone remodeling is initiated by osteoclastic resorption followed by osteoblastic formation of new bone. Receptor activator of nuclear factor kappaB ligand (RANKL) is a newly described regulator of osteoclast formation and function, the activity of which appears to be a balance between interaction with its receptor RANK and with an antagonist binding protein osteoprotegerin (OPG). Therefore, we have examined the relationship between the expression of RANKL, RANK, and OPG and indices of bone structure and turnover in human cancellous bone from the proximal femur. Bone samples were obtained from individuals with osteoarthritis (OA) at joint replacement surgery and from autopsy controls. Histomorphometric analysis of these samples showed that eroded surface (ES/BS) and osteoid surface (OS/BS) were positively associated in both control (p < 0.001) and OA (p < 0.02), indicating that the processes of bone resorption and bone formation remain coupled in OA, as they are in controls. RANKL, OPG, and RANK messenger RNA (mRNA) were abundant in human cancellous bone, with significant differences between control and OA individuals. In coplotting the molecular and histomorphometric data, strong associations were found between the ratio of RANKL/OPG mRNA and the indices of bone turnover (RANKL/OPG vs. ES/BS: r = 0.93, p < 0.001; RANKL/OPG vs. OS/BS: r = 0.80, p < 0.001). These relationships were not evident in trabecular bone from severe OA, suggesting that bone turnover may be regulated differently in this disease. We propose that the effective concentration of RANKL is related causally to bone turnover.

Adult↗

PubMed2001

Expression of alternatively-spliced MDM2 transcripts in giant cell tumours of bone.

Giant cell tumours of bone (GCT) are characterized histologically by multinucleated bone resorbing giant cells in a background of ovoid spindle-shaped mesenchymal cells. Current evidence suggests that the latter comprise the tumour element of these lesions, although there are basic questions as to the factors that contribute to the tumourigenesis and progression of GCT. The deregulation of the p53/MDM2 pathway is an important pathogenetic event in many tumour types, prompting us to assess the expression of MDM2 by the stromal cells and giant cells of GCT. Northern blot analysis demonstrated that most of the GCT samples examined expressed increased levels of MDM2 when compared to normal human bone cells. However, Southern analysis failed to show any evidence of MDM2 gene amplification in the same samples, suggesting that increased levels of MDM2 mRNA were not a direct result of gene amplification, but rather due to altered transcriptional regulation of MDM2 gene. By RT-PCR analysis we found that 7/8 giant cell tumours expressed strongly a short alternatively spliced variant of MDM2, whereas other tumours of bone and normal human bone cells expressed predominantly full length MDM2. Sequence analysis confirmed this variant to be MDM2-b, a variant previously reported to confer a transformed phenotype. Cell fractionation of the GCTs has shown that the MDM2-b splice variant was expressed exclusively in the stromal population, whereas the full length MDM2 was expressed in the multinucleated giant cells of these lesions. Overexpression of a green fluorescent protein-tagged MDM2-b in human embryonic kidney cells (HEK-293), demonstrated predominantly nuclear localisation. Immunoprecipitation studies showed that MDM2-b is unable to physically associate with the p53 tumour suppressor protein. These results are consistent with the hypothesis that the stromal cells comprise the tumour element in giant cell tumours of bone and we speculate that expression of the MDM2-b splice variant contributes to their transformed phenotype in a p53 independent manner.

Alternative Splicing↗

PubMed2000

Coordinated cytokine expression by stromal and hematopoietic cells during human osteoclast formation.

An in vitro culture system to generate human osteoclasts (OC) was recently described in which OC precursors in the human peripheral blood mononuclear cell (PBMC) population differentiate in the presence of murine ST-2 stromal cells. We used this culture system to define the cytokine environment in which human OC form and to determine the separate contributions of the stromal and hematopoietic elements. We designed a panel of reverse transcriptase-polymerase chain reaction (RT-PCR) primers that specifically amplify the respective murine or human mRNA species that correspond to cytokines and their cognate receptors previously shown to promote or inhibit OC differentiation. ST-2 cells were cocultured with human PBMC for up to 21 days in the presence of 1alpha,25(OH)(2) vitamin D(3), dexamethasone, and recombinant human macrophage-colony stimulating factor (M-CSF). OC formation was monitored by the appearance of cells that were positive for tartrate-resistant acid phosphatase (TRAP) and able to form resorption lacunae on slices of dentine. We found that the ST-2 cells in these cultures express messenger RNA (mRNA) encoding a repertoire of many of the reported osteoclastogenic factors (interleukins [IL]-1/IL-1R1, IL-11, IL-6/IL-6R, and IL-17 transforming growth factor [TGF]-beta), as well as the recently described OC differentiation factor (ODF/TRANCE/RANKL). The stromal cells also expressed mRNA encoding two molecules shown to be inhibitory to osteoclastogenesis, osteoprotegerin (OPG) and IL-18. OPG, IL-1, IL-1R1, IL-6, IL-6R, IL-11R, IL-17, IL-18, IL-18R, TGF-beta, and M-CSF were expressed by both the stromal cells and the PBMC. Expression of mRNA encoding RANK, IL-1R2, and c-fms, was specific for the PBMC. In addition, PBMC were found to express sIL-6R, granulocyte macrophage (GM)-CSF, GM-CSFRalpha, and tumor necrosis factor (TNF)-alpha. Whereas this indicated that human OC formation occurs in a complex environment of many positive and negative influences, we identified three apparent features of the cytokine environment that may be a characteristic of normal osteoclast formation. First, the ratio of mouse ODF:OPG mRNA was found to increase during the cocultures, consistent with a key role for ODF in the promotion by stromal cells of OC formation. Second, we found that mRNA encoding IL-1 and IL-17, as well as IL-6 and sIL-6R, were coordinately expressed by the PBMC. Third, analysis of the culture medium showed that the PBMC secreted IL-1, IL-6, and TNF-alpha protein only in coculture with ST-2 cells during the first few days of osteoclast development. We conclude that human OC formation occurs in a complex environment of many positive and negative influences; however, these are likely to be strictly regulated by a coordinated cytokine response of both stromal and hematopoietic cells.

Animals↗

PubMed2000

Expression of fibrillins and other microfibril-associated proteins in human bone and osteoblast-like cells.

Fibrillin-containing microfibrils are structural components of extracellular matrices of a diverse range of tissues, including bone. Their importance in bone biology is illustrated by the skeletal abnormalities manifest in the congenital disorder, Marfan syndrome, which results from mutations in the fibrillin-1 gene. We investigated the expression of fibrillins and other microfibril-associated proteins in human bone and bone-derived osteoblasts. Analysis of RNA extracted from cancellous bone showed expression of mRNAs encoding fibrillin-1 and -2, MAGP-1 and -2, LTBP-2, and MP78/70 (Big-h3). In demineralized normal mature bone, fibrillin-1 was immunolocalized to fibrils within the bone matrix and pericellularly to cells lining the endosteal surfaces of trabecular bone, some osteocytes, and cells associated with blood vessels. LTBP-2 was also identified at the endosteal surface and within the bone matrix in a lamellar fashion. In addition, primary osteoblast-like cells cultured from human trabecular bone (obtained from patients at joint replacement surgery) were found to express abundant mRNA for fibrillins and associated glycoproteins. Moreover, using western blot analysis, fibrillin-1 protein was shown to be secreted into the medium and to be deposited into the cell layer. Immunofluorescence staining of the cell layer visualized fibrillin-1 in the matrix as a three-dimensional network of fine filaments. Expression of fibrillin-1 by osteoblast-like cells was constitutive, and a number of skeletally active agents had little effect on mRNA or protein levels. These results show that human osteoblasts from mature bone express fibrillins and other microfibril-associated proteins, and suggest a role for these molecules in adult human bone.

Adult↗

PubMed2000

A simple and rapid technique for the detection of Epstein-Barr virus DNA in HIV-associated oral hairy leukoplakia biopsies.

A method of generating nucleic acid probes by polymerase chain reaction (PCR) for the detection of Epstein-Barr virus (EBV)-DNA by in situ hybridization in oral hairy leukoplakia (OHL) lesions is described. This method has the advantage over older methods of being cheaper, quicker and retaining sensitivity and specificity. Purified PCR products of Epstein-Barr virus DNA of 110 bp and 328 bp were labelled with biotin by nick translation or random primer labelling and were compared in in situ hybridization experiments with probes prepared by incorporation of biotin-labelled nucleotides in the PCR reaction mixture, with EBV viral DNA as a template. These probes were applied to 18 OHL tongue biopsies known to be positive for EBV-DNA, using a commercially available biotin-labelled BamHI "V" fragment EBV-DNA probe. To determine the specificity of the probes, we applied them to 20 normal tongue tissue samples and to 12 biopsies taken from keratotic tongue lesions from patients without risk factors for HIV infection and known to be negative for EBV-DNA. Clear positive signals for EBV-DNA were detected in all 18 cases of OHL biopsies using the amplimer of 328 bp labelled by PCR and random primer labelling. However, nick translation labelling was less efficient and sensitive. All control specimens were negative for EBV-DNA.

AIDS-Related Opportunistic Infections↗

PubMed2000

Inhibition of human lung carcinoma cell growth by apoptosis induction using Semliki Forest virus recombinant particles.

We have utilised cell cultures and growth of tumours in nude mice to assess further the potential of the Semliki Forest virus (SFV) vector as a cancer therapy agent. This vector is a transient RNA-based expression vector, and we have previously shown that SFV and its derived vector can induce p53-independent apoptosis by expression of the nonstructural region of the virus genome. Apoptosis induction is therefore an inherent property of the vector and is not dependent on heterologous gene expression. SFV recombinant suicide particles (rSFV) were shown to induce apoptosis in H358a cells, which are human non-small cell lung carcinoma cells deleted in p53. EGFP-expressing rSFV also inhibited the growth of developing H358a spheroids. Direct injection of rSFV into H358a tumours subcutaneously implanted as xenografts in nu/nu mice inhibited tumour growth, and in some cases caused complete regression. It is concluded that tumour growth suppression induced by rSFV was due to apoptosis induction and that the vector has an inherent cell death-promoting and antitumour activity. These results, as well as previous work by other authors on targeting and immune stimulation using alphavirus vectors, indicate that SFV recombinant particles in particular have considerable potential for further exploitation as a cancer therapy agent.

Animals↗

PubMed2000

Recombinant Semliki Forest virus particles expressing louping ill virus antigens induce a better protective response than plasmid-based DNA vaccines or an inactivated whole particle vaccine.

Louping ill virus (LIV) infection of mice was used as a model to evaluate the protective efficacy of Semliki Forest virus (SFV)-based vaccines in comparison to a standard DNA vaccine and a commercial chemically inactivated vaccine. The recombinant SFV-based vaccines consisted of suicidal particles and a naked layered DNA/RNA construct. The nucleic acid vaccines expressed the spike precursor prME and the nonstructural protein 1 (NS1) antigens of LIV. Three LIV strains of graded virulence for mice were used for challenge. One of these was a naturally occurring antibody escape variant. All vaccines tested induced humoral immunity but gave varying levels of protection against lethal challenge. Only recombinant SFV particles administered twice gave full protection against neuronal degeneration and encephalitis induced by two of the three challenge strains, and partial protection against the highly virulent strain, whereas the other vaccines tested gave lower levels of partial protection.

Animals↗

PubMed2000

Enhanced expression of osteocalcin mRNA in human osteoarthritic trabecular bone of the proximal femur is associated with decreased expression of interleukin-6 and interleukin-11 mRNA.

Few studies have investigated the factors or mechanisms that may lead to structural changes in OA bone. This study examines the in vivo expression of messenger RNA encoding the osteoclastogenic cytokines interleukin-6 (IL-6) and interleukin-11 (IL-11), together with the osteoblastic marker osteocalcin (OCN) and the calcitonin receptor (CTR), which in bone is exclusively expressed by osteoclasts. Total RNA was isolated from intertrochanteric trabecular bone from OA patients, and from controls taken at autopsy. The patterns of mRNA expression of IL-6, IL-11, OCN, and CTR were examined using reverse-transcription polymerase chain reaction (RT-PCR) by determining the relative ratios of the amplified products with respect to glyceraldehyde-3-phosphate dehydrogenase (GAPDH). Both IL-6 and IL-11 mRNA were significantly less abundant in OA than in the control group. Expression of IL-11 mRNA decreased significantly with age for both groups. OCN mRNA expression was significantly more abundant in OA, and there was no significant difference for CTR mRNA between the two groups. For both OCN and CTR in OA, expression increased significantly with increasing age. These differences in expression between the OA and control groups are consistent with an hypothesis that biochemical and genetic factors in bone can contribute or perhaps underlie the degenerative joint changes seen in OA.

Aged↗

PubMed2000

Expression of osteoclast differentiation signals by stromal elements of giant cell tumors.

The mechanisms by which primary tumors of the bone cause bone destruction have not been elucidated. Unlike most other lytic bone tumors, osteoclastomas, otherwise known as giant cell tumors (GCT), contain osteoclast-like cells within the tumor stroma. A new member of the TNF-ligand superfamily member, osteoclast differentiation factor (ODF/OPGL/RANKL/TRANCE), was recently identified. ODF was shown to directly stimulate osteoclastogenesis, in the presence of M-CSF. In this study, the expression of ODF was examined in a number of tumor samples associated with bone lysis in vivo. In addition, we investigated expression of the ODF receptor on osteoclast precursors, RANK, as well as the ODF inhibitor osteoprotegerin (OPG), and another TNF-ligand superfamily member, TRAIL, previously shown to abrogate the inhibitory effects of OPG. We report here the novel finding that GCT stromal cells contain abundant ODF mRNA, whereas the giant cell population exclusively expresses RANK mRNA. These results are consistent with the osteoclast-mediated bone destruction by these tumors. We also report the expression of OPG and TRAIL mRNA in GCT samples. A comparison with other lytic and nonlytic tumors of bone showed that GCT express more ODF and TRAIL mRNA relative to OPG mRNA. In addition, GCT were found to express a number of cytokines previously reported to play central roles in osteoclastogenesis, namely, IL-1, -6, -11, -17, as well as TNF-alpha. Importantly, GCT were also found to express high levels of M-CSF mRNA, a cytokine shown to be an essential cofactor of ODF, and a survival factor for mature and developing osteoclasts. Furthermore, expression of these molecules by stromal cells isolated from GCT continued in vitro. Thus GCT constitutively express all of the signals that are currently understood to be necessary for the differentiation of osteoclasts from precursor cells.

Apoptosis Regulatory Proteins↗

PubMed1999

Bidirectional signaling between stromal and hemopoietic cells regulates interleukin-1 expression during human osteoclast formation.

Interleukin-1 (IL-1) has been shown to promote osteoclast (OC) differentiation, in addition to acting as a survival factor for mature osteoclasts. In this study, we investigate the expression of IL-1 during human osteoclast formation, taking advantage of a recently reported in vitro culture system that generates human OC from precursors in the peripheral blood mononuclear cell (PBMC) fraction, in the presence of murine stromal cells. This system enabled us to use species-specific probes and immunoassays to determine the respective cytokine contributions of the stromal cell and hemopoietic cell populations. Formation of functional osteoclasts occurred in cocultures of human PBMC and ST-2 cells for up to 21 days in the presence of 1alpha,25(OH)2-vitamin D3, dexamethasone, and recombinant human macrophage colony-stimulating factor (rhM-CSF). Total RNA was prepared at intervals during the cocultures and reverse transcriptase-polymerase chain reaction (RT-PCR) was performed using primers designed to amplify specifically the mRNA species corresponding to the respective murine or human IL-1alpha and IL-1beta isoforms. Using human-specific primers, it was found that the hemopoietic cell component expressed both IL-1alpha and IL-1beta mRNA. Specific measurement of secreted human IL-1beta protein showed greatly augmented levels in coculture compared with hemopoietic cells grown in the absence of ST-2 cells, consistent with the known signaling from stromal cells to hemopoietic cells during osteoclastogenesis. Specific detection of mouse mRNA products showed that the ST-2 stromal cells in the coculture also expressed mRNA corresponding to IL-1alpha and IL-1beta. The expression of both mouse and human IL-1 mRNA was found to decline over the course of the coculture, although the level of IL-1alpha mRNA relative to IL-1beta mRNA remained constant, indicating that the two isoforms were coregulated in both cell populations under these conditions. Importantly, the hemopoietic cells were found to influence strongly the IL-1 mRNA levels in ST-2 cells, such that mouse IL-1alpha and IL-1beta mRNA levels were greatly enhanced in coculture, compared with ST-2 cells alone. Secreted mouse IL-1beta protein was upregulated in coculture in parallel with mRNA levels. However, the absolute levels of mouse IL-1beta achieved were more than 20-fold lower than the human IL-1beta levels. Prostaglandin estradiol (PGE2) levels were measured and found to be greatly increased in the coculture compared with ST-2 cells or hemopoietic cells alone, consistent with evidence that IL-1 action in osteoclastogenesis is mediated by PGE2. These results provide novel evidence that bidirectional signaling between stromal and hemopoietic cells may be important in the generation of human osteoclasts.

Acid Phosphatase↗

PubMed1999

Cell death mechanisms in the olfactory bulb of rats infected intranasally with Semliki forest virus.

Semliki Forest virus (SFV) infection of mice is used as a model to study pathogenic processes occurring in viral encephalitis. It has previously been shown that avirulent strains of SFV differ from virulent strains in showing restricted multiplication in neurones and in producing localized rather than widespread lesions in the central nervous system (CNS). Restricted neuronal damage is age-dependent and does not occur in neonatal animals. In this study, cell death mechanisms occurring in the CNS of adult rats infected intranasally (i.n.) with a virulent (SFV4) and an avirulent (A7) strain of SFV have been investigated. Although i.n. infection of rats was less efficient than that of mice, SFV4 reached a higher titre in the CNS of infected animals than A7. Neuronal destruction and leucocytic infiltration occurred throughout the forebrain of SFV4-infected rats. A7-infected rats remained clinically normal although degenerate neurons and inflammatory changes were present primarily in the olfactory system. Following infection with either A7-SFV or SFV4, TUNEL-positive nuclei were seen in areas of leucocytic infiltration and among the poorly differentiated cells of the rostral migratory stream. Migrating cells had condensed nuclear chromatin, compacted cytoplasm and intact cellular membranes, characteristic of apoptosis, and were sparsely immunolabelled for viral antigen. In SFV4-infected rats, large numbers of contiguous neurones in forebrain areas exhibited cytoplasmic eosinophilia and karyolysis and were surrounded by phagocytic cells. Such neurones contained dense intracytoplasmic deposits of viral antigen and showed weak cytoplasmic TUNEL staining; electron microscopy showed membrane disruption, organelle disintegration, irregular chromatin condensation and cytoplasmic aggregation of virus particles. Bcl-2 staining was similar in infected and control rats and was most intense in randomly distributed Purkinje cells in the cerebellum; neurons in the olfactory bulbs were unstained. These findings indicate that during SFV encephalitis, infiltrating leucocytes and neural precursor cells undergo apoptosis whilst productively infected neurons undergo necrosis.

Alphavirus Infections↗

PubMed1999

Recombinant Semliki Forest virus particles encoding the prME or NS1 proteins of louping ill virus protect mice from lethal challenge.

Recombinant Semliki Forest virus (rSFV) vaccines encoding louping ill virus (LIV) genes prME and NS1 were examined. Cells transfected with rSFV-prME RNA showed correct processing of the precursor prME and the release into the medium of M and E proteins in particulate form, whilst rSFV-NS1-transfected cells secreted glycosylated, heat-labile NS1 dimers. Mice immunized with rSFV particles produced antibodies against prME and NS1 that were mainly of the IgG2a subtype, indicating that a T-helper 1 immune response was induced. Immunization with prME- or NS1-encoding particles induced T-cell proliferation. Mice vaccinated intraperitoneally (i.p.) with rSFV-prME and/or rSFV-NS1 were significantly protected from lethal i.p. challenge by two strains of LIV, the virulent LI/31 strain, from which the commercial LIV vaccine is derived, and the less-virulent LI/I antibody-escape variant. Intranasal (i.n.) vaccination was protective for rSFV-prME only against LI/31 challenge and not against challenge with LI/I. Immunization with rSFV-NS1 was protective against i.p. and i.n. challenge with both virus strains when given i.p., but was not protective when given i.n. For unvaccinated mice infected with LIV, all animals showing clinical signs had severe degenerative and inflammatory lesions in the central nervous system. None of the rSFV-vaccinated mice that survived challenge showed central nervous system pathology, with the exception of mild leptomeningitis in a minority of LI/31-infected mice. This suggests that protection following immunization with rSFV must occur at early stages of LIV infection.

Animals↗