Identification of Epstein-Barr Virus Lytic and Latent RNA Transcripts in Post-transplant Lymphoproliferative Disorder

Thirty-three specimens from 25 transplant recipients with Epstein-Barr virus-associated lymphoproliferative disease were studied by in situ hybridization for 2 lytic and 4 latent Epstein-Barr virus transcripts. All specimens were found to contain at least 1 latent transcript while 28 were positive for at least 1 lytic transcript. The amount of Epstein-Barr virus infection and lytic activity varied with histopathology and number of involved sites. Patients with localized polymorphous disease contained the lowest number of infected cells with an almost equal lytic:latent ratio. Disseminated polymorphous and single and multisite monomorphous specimens showed a large latent cell population. Minimal lytic activity was seen in single site monomorphous specimens, but disseminated monomorphous specimens showed the highest levels of lytic transcripts. Most post-transplant lymphoproliferative disorder specimens demonstrate lytic Epstein-Barr virus transcripts, although the majority of cells contain latent Epstein-Barr virus. Lytic activity is highest in patients with disseminated disease. Lytic Epstein-Barr virus infection may aid in the development and maintenance of lymphoproliferative disorders in transplant recipients.

Detection of the exogenous hGDNF in gerbils under the treatment with AxCAhGDNF adenoviral vector

Glial cell line-derived neurotrophic factor (GDNF) is one of the most potent neurotrophic factors and promotes survival in many populations of cells. We examined the neuroprotective effect of an adenoviral vector encoding glial cell line-derived neurotrophic factor (AxCAhGDNF) on the transient global ischemia [Brain Res. 885 (2000) 273-282]. Gerbils received AxCAhGDNF or an adenoviral vector encoding bacterial beta-galactosidase gene (AxCALacZ) through administration into the lateral ventricle. Two days later, occlusion of the common carotid arteries for 5 min bilaterally using aneurysm clips produced transient global forebrain ischemia. Animals showed intense immunolabeling for GDNF in ependymal cells on 2, 4 and 7 days after the operation. The exogenous gene transducted by the adenovirus in the same cells was detected by in situ hybridization. The treatment with AxCAhGDNF significantly prevented the loss of hippocampal CA-1 pyramidal neurons 2 to 7 days after the operation, as compared to AxCALacZ treatment. Also terminal deoxynucleotidyl transferase-mediated dUTP-biotin in situ nick end labeling (TUNEL) staining was markedly reduced in the case with AxCAhGDNF treatment at 7 days after the operation. In this paper, we describe in detail the techniques for the detection of the exogenous gene of hGDNF under the treatment with AxCAhGDNF.

CXCR3 expression in human central nervous system diseases

The CXCR3 chemokine receptor, expressed on activated T lymphocytes, is seen within the central nervous system (CNS) in inflammatory conditions where a T-cell response is prominent. However, the distribution of CXCR3 in parenchymal CNS cells is unknown. Using a monoclonal antibody against CXCR3 and post-mortem tissue of patients with and without CNS pathology, we have determined its expression pattern. CXCR3 was found in subpopulations of cells morphologically consistent with astrocytes, particularly reactive astrocytes, and in cerebellar Purkinje cells. It was also detected in arterial endothelial and smooth muscle cells, particularly in areas associated with atherosclerotic plaques. CXCR3-positive astrocytes were particularly prominent in the CNS of HIV-positive patients, in patients with Multiple Sclerosis (MS), in ischaemic infarcts and in astrocytic neoplasms. Immunofluorescence studies of mixed adult primary glial cultures and fetal glial cultures also showed expression of CXCR3 in astrocytes. CXCR3 mRNA was detected in Purkinje cells by in situ hybridization with a CXCR3-specific probe. Thus, the predominant expression of CXCR3 in reactive astrocytes may indicate that it plays a role in the development of reactive gliosis in a variety of infectious, inflammatory, vascular and neoplastic processes in the CNS. The relationship between CXCR3 expression in astrocytes to its expression in Purkinje cells, endothelial cells and smooth muscle cells is yet to be determined.

Rescue of ischemic brain injury by adenoviral gene transfer of glial cell line-derived neurotrophic factor after transient global ischemia in gerbils

Glial cell line-derived neurotrophic factor (GDNF), a member of the transforming growth factor (TGF)-beta superfamily, is one of the most potent neurotrophic factors and promotes survival of many populations of cells. We examined neuroprotective effect of an adenoviral vector encoding glial cell line-derived neurotrophic factor (AxCAhGDNF) on the transient global ischemia. Gerbils received administration of AxCAhGDNF or an adenoviral vector encoding bacterial beta-galactosidase gene (AxCALacZ) through the lateral ventricle. Two days later, occluding bilateral common carotid arteries for 5 min using aneurysm clips produced the transient global forebrain ischemia. Animals showed intense immunolabeling for GDNF in ependymal cells on 2, 4 and 7 days after the operation. The exogenous gene transducted by adenovirus in the same cells was detected by in situ hybridization. The treatment with AxCAhGDNF significantly prevented the loss of hippocampal CA1 pyramidal neurons 2 to 7 days after the operation, as compared to AxCALacZ treatment. Also terminal deoxynucleotidyl transferase-mediated dUTP-biotin in situ nick end labeling (TUNEL) staining was markedly reduced in the case with AxCAhGDNF treatment at 7 days after the operation. These results indicated that the adenovirus-mediated gene transfer of GDNF might prevent the delayed neuronal death of stroke and other disorders of the cerebral vasculature.

In human skin, UVB initiates early induction of IL-10 over IL-12 preferentially in the expanding dermal monocytic/macrophagic population

In contrast to Langerhans cells, which make interleukin (IL)-12, differentiated macrophages that infiltrate the epidermis 72 h after ultraviolet B (UV) irradiation potently produce IL-10 mRNA and secrete IL-10 protein. We asked whether differentiated UV macrophages in the epidermis acquired their activated, IL-10hi status as a result of entering the epidermis or as a result of encountering UV-induced changes in the dermal microenvironment. In this study, sequential section immunostaining directly showed dynamic and reciprocal changes of infiltrating CD11b+ macrophages and CD1a+ Langerhans cell loss in human epidermis and dermis after in vivo UV exposure in relation to the microanatomic localization of newly appearing dermal cells that stain for IL-10 mRNA by in situ hybridization. Using quantitative reverse transcriptase polymerase chain reaction on purified dermal cell subsets, the first significant rise in IL-10 mRNA occurred 6 h after UV in the dermal CD11b+ (CD1-, 3-, 24-, 56-) monocytic/macrophagic population. Significant induction of IL-10 mRNA 24 h post-UV was limited to the CD11b+ CD1- subset (p = 0.006). The fold increase of IL-10 mRNA relative to 0 h by the CD11b+ dermal monocytic/macrophagic population peaked at 24-48 h and tapered thereafter. Intense IL-10 production by macrophages in the epidermis appeared to follow dermal changes, with maximum production at 72 h, indicating migration/activation of this population from the dermis, and the remainder of dermal cells, depleted of monocyte/macrophages and Langerhans cell-like antigen-presenting cells, showed no increase in IL-10 at any time point post-UV. IL-10 protein-producing CD11b+ macrophages in the dermis were also documented by flow cytometry. IL-12 mRNA was differentially regulated from IL-10 after UV, in that IL-12 was consistently downregulated in the CD11b+ monocytic/macrophagic population (p < 0.0002). Taken together, monocytic/macrophagic cells with high IL-10 and low IL-12 expression initially appear in the dermis as early as 6 h, and then appear in the epidermis, implicating the dermis as the primary site of activation/signaling for IL-10 upregulation in cutaneous antigen-presenting cells.

In situ hybridization and its diagnostic applications in pathology

In situ hybridization (ISH) is a technique by which specific nucleotide sequences are identified in cells or tissue sections. These may be endogenous, bacterial or viral, DNA or RNA. On the basis of research applications, the technique is now being translated into diagnostic practice, mainly in the areas of gene expression, infection and interphase cytogenetics. Diagnostic applications are most often based on short nucleotide sequences (oligomers) labelled with non-isotopic reporter molecules, and sites of binding may be localized by histochemical or immunohistochemical methods. The technique can be applied to routinely fixed and processed tissues; with some targets, it is even possible to obtain hybridization in autopsy material. ISH has been used to detect messenger RNA (mRNA) as a marker of gene expression, where levels of protein storage are low; for example, to confirm an endocrine tumour as the source of excess hormone production. Its application in infectious diseases has to date been mainly in viral infections, such as the typing of human papillomavirus (HPV) or the detection of Epstein-Barr virus by the presence of small nuclear RNAs (EBERs). The expression of mRNAs for histone proteins has been used to detect cells in S phase, and related methods may be applied to detect apoptotic cells. Using probes to chromosome-specific sequences, it is possible to detect aneuploidy, and to document changes in specific chromosomes, which may have prognostic significance in some tumours, such as B-cell chronic lymphatic leukaemia. Using sequence-specific probes, translocations can be identified, such as the t(11;12) of Ewing's sarcoma. This review presents an outline of the technique of in situ hybridization and discusses areas of current and potential diagnostic application.

The use of microwave irradiation as a pretreatment to in situ hybridization for the detection of measles virus and chicken anaemia virus in formalin-fixed paraffin-embedded tissue

Microwave irradiation was investigated as a pretreatment to in situ hybridization on formalin-fixed, paraffin-embedded tissue. Two probe/tissue systems were used: a single-stranded RNA probe for the detection of measles virus nucleocapsid genome in subacute sclerosing panencephalitis brain tissue, and a double stranded DNA probe for chicken anaemia virus in thymus of chicken infected with the virus. Microwaving, when used as sole pretreatment, was not as effective as the more traditional enzyme pretreatments for in situ hybridization. However, when used in combination with existing pretreatments, a significant increase was found in hybridization signal in both brain and thymus tissue. This was emphasized when combination enzyme/microwave pretreatments were used prior to detection of measles virus by in situ hybridization in a series of five archival subacute sclerosing panencephalitis cases. The use of microwave irradiation would be recommended as a means of supplementing in situ hybridization methods, especially when using long-term formalin fixed paraffin-embedded tissue.

Reduced formamide content and hybridization temperature results in increased non-radioactive mRNA in situ hybridization signals

To define conditions for highly sensitive non-radioactive mRNA in situ hybridization on cryostat sections the influence of decreased formamide content and hybridization temperature was studied. The examination was performed on fibromatosis nodules of palmar fibromatosis visualizing the beta actin mRNA of myofibroblasts. The results show that a decrease in formamide content and hybridization temperature is able to enhance the sensitivity of mRNA detection applicating digoxigenin labelled DNA oligodeoxynucleotide. The best hybridization signal could be obtained under formamide-free conditions. In conclusion, a simplified sensitive formamide-free mRNA in situ hybridization protocol using oligonucleotide probes on human tissue cryostat sections is presented. The negative formamide effect is seen as a result of the chemical interaction of formamide with nucleic acid strands. An omission of formamide is suggested if the target as well as the probe are single stranded.