Biomedical subjects

Z J Chen

Publications and source records attributed to Z J Chen.

At least 19 recordsLinked to original sources

PubMed1998

Polyreactive antigen-binding B cells are the predominant cell type in the newborn B cell repertoire.

Polyreactive antibodies bind to a variety of different self and non-self antigens. The B cells that make these antibodies express the polyreactive lg receptor on their surface. To determine the frequency of polyreactive antigen-binding B cells in peripheral blood, we incubated two different antigens, one (insulin) labeled with fluorescein isothiocyanate and the other (beta-galactosidase) with phycoerythrin, with peripheral B cells. The percentage of cells that bound these antigens was determined with the fluorescence-activated cells sorter. Approximately 21% of adult B cells bound insulin, 28% bound beta-galactosidase, and 11% bound both antigens. In contrast to B cells in the adult repertoire, 49% of B cells in cord blood bound insulin, 54% bound beta-galactosidase, and 33% bound both antigens. The properties of polyreactive antigen-binding B cells in adult and cord blood were similar, except for the fact that almost all the polyreactive antigen-binding B cells in cord blood were CD5 positive (93%), whereas only 40% of the polyreactive antigen-binding B cells in adult peripheral blood were CD5 positive, indicating that the CD5 marker is not directly linked to polyreactivity. The percentage of polyreactive antigen-binding B cells in patients with Sjögren's syndrome, systemic lupus erythematosus and rheumatoid arthritis was equal to or slightly below that found in the normal adult B cell repertoire. It is concluded that polyreactive antigen-binding B cells are a major constituent of the normal adult B cell repertoire and are the predominant cell type in the newborn B cell repertoire.

Adolescent↗

PubMed1998

Distribution and stability of antisense phosphorothioate oligonucleotides in rodent brain following direct intraparenchymal controlled-rate infusion.

OBJECT: High-flow microinfusion is a novel technique for delivery of compounds directly into brain parenchyma, bypassing the blood-brain barrier. The feasibility of this technique has been demonstrated with low-molecular-weight compounds, macromolecular dyes, and proteins. Delivery of antisense oligonucleotides into brain parenchyma represents an additional potential application of this technique not previously described. In this report the authors sought to examine the distribution and disposition of phosphorothioate oligodeoxynucleotide (PS-ODN) for this reason. METHODS: An 18-mer 35S-PS-ODN (Mr approximately 6000) was infused over 1 hour into the caudate putamen of Fischer 344 rats. At 1, 6, 12, 24, and 48 hours after beginning the infusion, the brains were extracted and analyzed using quantitative autoradiographic techniques. Cerebrospinal fluid (CSF) was also aspirated from the cisterna magna and was analyzed to determine the radioactivity and stability of the 35S-PS-ODN. At 1 hour, the infused ODN was uniformly distributed in brain tissue, with a maximum average concentration of 4806.5 +/- 210.5 nCi/g. This represents a tissue concentration of 19.2 +/- 0.84 microM. Extensive spread into surrounding parenchyma was observed over the ensuing 47 hours. The 35S-PS-ODN radioactivity peaked in the CSF at the end of the 1-hour infusion, containing 1% (50 +/- 20 nCi) of the infused radioactivity. Activity then decayed exponentially over 11 hours, but stabilized at a lower CSF content of 0.2% (1 +/- 0.1 nCi) thereafter. The volume of distribution was 105 +/- 7.9 mm3 at 1 hour, representing a volume of distribution/volume of infusion ratio of 5.2. The volume of distribution increased to 443 +/- 62.3 mm3 at the end of 48 hours, whereas the average minimum tissue concentration decreased from 15.2 microM to 3.2 microM. Undegraded 18-mer was observed throughout the 48-hour period by means of 20% polyacrylamide/7 M urea gel electrophoresis. The animals tolerated the infusion without evidence of toxicity and minimal structural changes in tissue were observed on histological investigation. CONCLUSIONS: The authors found that PS-ODNs can be safely delivered in high concentrations to wide areas of rat brain by using high-flow microinfusion and are stable even after 48 hours in situ.

Animals↗

PubMed1997

Epigenetic silencing of RNA polymerase I transcription: a role for DNA methylation and histone modification in nucleolar dominance.

Nucleolar dominance is an epigenetic phenomenon that describes nucleolus formation around rRNA genes inherited from only one progenitor of an interspecific hybrid or allopolyploid. The phenomenon is widespread, occurring in plants, insects, amphibians, and mammals, yet its molecular basis remains unclear. We have demonstrated nucleolar dominance in three allotetraploids of the plant genus Brassica. In Brassica napus, accurately initiated pre-rRNA transcripts from one progenitor, Brassica rapa are detected readily, whereas transcripts from the approximately 3000 rRNA genes inherited from the other progenitor, Brassica oleracea, are undetectable. Nuclear run-on confirmed that dominance is controlled at the level of transcription. Growth of B. napus seedlings on 5-aza-2'-deoxycytidine to inhibit cytosine methylation caused the normally silent, under-dominant B. oleracea rRNA genes to become expressed to high levels. The histone deacetylase inhibitors sodium butyrate and trichostatin A also derepressed silent rRNA genes. These results reveal an enforcement mechanism for nucleolar dominance in which DNA methylation and histone modifications combine to regulate rRNA gene loci spanning tens of megabase pairs of DNA.

Azacitidine↗

PubMed1997

Transcriptional analysis of nucleolar dominance in polyploid plants: biased expression/silencing of progenitor rRNA genes is developmentally regulated in Brassica.

Nucleolar dominance is an epigenetic phenomenon that describes the formation of nucleoli around rRNA genes inherited from only one parent in the progeny of an interspecific hybrid. Despite numerous cytogenetic studies, little is known about nucleolar dominance at the level of rRNA gene expression in plants. We used S1 nuclease protection and primer extension assays to define nucleolar dominance at a molecular level in the plant genus Brassica. rRNA transcription start sites were mapped in three diploids and in three allotetraploids (amphidiploids) and one allohexaploid species derived from these diploid progenitors. rRNA transcripts of only one progenitor were detected in vegetative tissues of each polyploid. Dominance was independent of maternal effect, ploidy, or rRNA gene dosage. Natural and newly synthesized amphidiploids yielded the same results, arguing against substantial evolutionary effects. The hypothesis that nucleolar dominance in plants is correlated with physical characteristics of rRNA gene intergenic spacers is not supported in Brassica. Furthermore, in Brassica napus, rRNA genes silenced in vegetative tissues were found to be expressed in all floral organs, including sepals and petals, arguing against the hypothesis that passage through meiosis is needed to reactivate suppressed genes. Instead, the transition of inflorescence to floral meristem appears to be a developmental stage when silenced genes can be derepressed.

Base Sequence↗

PubMed1997

Activation of the IkappaB alpha kinase complex by MEKK1, a kinase of the JNK pathway.

Both NF-kappaB and c-Jun are activated by cytokines such as TNF-alpha and by stresses such as UV irradiation. A key step in the activation of NF-kappaB is the phosphorylation of its inhibitor, IkappaB alpha, by a ubiquitination-inducible multiprotein kinase complex (IkappaB alpha kinase). A central kinase in the c-Jun activation pathway is mitogen-activated protein kinase/ERK kinase kinase-1 (MEKK1). Here, we show that MEKK1 induces the site-specific phosphorylation of IkappaB alpha in vivo and, most strikingly, can directly activate the IkappaB alpha kinase complex in vitro. Thus, MEKK1 is a critical component of both the c-Jun and NF-kappaB stress response pathways. Since the IkappaB alpha kinase complex can be independently activated by ubiquitination or MEKK1-dependent phosphorylation, it may be an integrator of multiple signal transduction pathways leading to the activation of NF-kappaB.

Animals↗

PubMed1997

Modulation of MMP-2 (gelatinase A) and MMP-9 (gelatinase B) by interferon-gamma in a human salivary gland cell line.

Gelatinases have been shown to be regulated by many cytokines and growth factors, and have been implicated in the pathogenesis of certain autoimmune diseases via tissue destruction. High levels of several cytokines, including IFN-gamma and TNF-alpha, have been demonstrated in the salivary gland microenvironment of patients with Sjogren's syndrome (SS). How these cytokines may be contributing to the pathogenesis of this disease is not well understood. We hypothesized that IFN-gamma with or without (+/-) TNF-alpha could be playing a role in the pathogenesis of SS via the regulation of matrix metalloproteinase (MMP) levels. This study examined the role of IFN-gamma and (+) TNF-alpha in the regulation of the matrix metalloproteinases, MMP-2 (72 kD gelatinase A) and MMP-9 (92 kD gelatinase B). A human salivary gland cell line (HSG) has been used as a possible in vitro model to study the role of IFN-gamma + TNF-alpha in the pathogenesis of SS. The HSG cell line, in the presence of IFN +/- TNF-alpha, displays increased MMP-2 and MMP-9 gelatinolytic activity, protein and RNA levels. The increase in MMP activity was partially blocked with an antibody against the IFN-gamma receptor, and this was associated with a complete inhibition of the previously described IFN-gamma +/- TNF-alpha antiproliferative effect. However, incubation of IFN-gamma treated HSG cells with the synthetic MMP inhibitor BB94 did not alleviate this antiproliferative effect. In addition, we demonstrate that there are very high levels of MMP-9 in the saliva of patients with SS when compared to healthy control subjects. These data suggest that cytokines could be regulating MMP production by salivary epithelial cells and thus indicate a potential role for these cells in the pathogenesis of SS.

Animals↗

PubMed1997

Interferon-gamma-induced JAK2 and STAT1 signalling in a human salivary gland cell line.

We have used a human salivary gland cell line (HSG) as a possible in vitro model to evaluate the effects of IFN-gamma on human salivary gland epithelium (Wu et al., 1994, 1996, 1997). In the present study, we examined the JAK-STAT signal-transduction pathway in IFN-gamma-treated HSG cells. We demonstrate that JAK2 and Stat1 are phosphorylated at tyrosine residues in a time- and concentration-dependent manner following exposure to IFN-gamma. In addition, we show that activation of this signalling pathway is decreased by the addition of a blocking antibody to the IFN-gamma receptor. The same maneuver is also able to reduce by approximately 50-70% the surface expression of two IFN-gamma-induced immunoregulatory molecules: HLA-DR and ICAM-1. These results demonstrate that the JAK2 and Stat1 signalling pathway is active in salivary-derived epithelial cells and may contribute to their immunopathologic destruction.

Antibodies↗

PubMed1997

Antiproliferative effect of c-myc antisense phosphorothioate oligodeoxynucleotides in malignant glioma cells.

OBJECTIVE: To improve the prognosis for primary malignant tumors of the central nervous system, new therapeutic strategies are needed. Antisense oligodeoxynucleotides (ODNs) offer the potential to block the expression of specific genes within cells. The proto-oncogene c-myc has long been implicated in the control of normal cell growth and its deregulation in the development of neoplasia. We therefore reasoned that a strategy using ODNs complementary to c-myc messenger ribonucleic acid would be a potent inhibitor of glioma cell proliferation. METHODS: A variety of antisense, sense, and scrambled (15-mer) phosphorothioate ODNs targeted to rat and human c-myc messenger ribonucleic acid were synthesized and added to the media of cultured RT-2 cells (a rat glioblastoma cell line). Cell growth was assessed by 3-[4,5-dimethylthiazol-2yl]-2,5-diphenyltetrazolium bromide dye assay 1 to 5 days after adding the ODNs. c-Myc protein expression was analyzed by Western blot analysis. The stability of the ODNs was confirmed by gel electrophoresis. RESULTS: Compared with cultures containing standard media, two of three antisense ODNs significantly inhibited the growth of glioma cells, whereas sense and scrambled sequence ODNs did not significantly affect cell growth at the concentrations tested. A human c-myc antisense sequence, which differed from the rat sequence by one base substitution, also had an inhibitory effect on RT-2 cells. Western blot analysis demonstrated that expression of immunoreactive c-Myc protein was also greatly reduced in the rat antisense ODN-treated cells (and not in sense-, scrambled-, or control-treated cells). The degree of reduction of c-Myc protein expression correlated well with the decrease in cell growth observed with several antisense ODNs. Phosphorothioate ODNs were stable in cell culture media for at least 5 days. CONCLUSION: These results suggest that c-Myc plays a critical role in glioma cell proliferation and demonstrate that antisense ODNs can suppress proto-oncogene expression and inhibit the proliferation of glioma cells. Our results indicate that the antiproliferative activity of these ODNs was mediated predominantly through sequence-specific antisense mechanisms, but that sequence-specific nonantisense effects may also contribute to the strongest effects demonstrated. These findings support a potential role for antisense strategies designed to inhibit c-myc expression in the treatment of malignant gliomas.

Animals↗

PubMed1996

Aquaporin 1 expression during the cell cycle in A5 cells.

Aquaporin 1 is an integral membrane protein which functions as a water channel. It is reportedly (Lanahan et al., 1992) encoded by a delayed early response gene. We asked if the expression of aquaporin 1 varied during the cell cycle in an epithelial cell line (A5) in which its is constitutively expressed. A5 cells were synchronized by double thymidine block and cell cycle stages defined by flow cytometric analysis. AQP1 mRNA and protein levels were highest when most cells were in G0/G1, then decreased approximately 40-60% when the cells moved into the S and G2/M phases. These results provide the first demonstration that constitutive aquaporin 1 expression can fluctuate during the cell cycle.

Animals↗

PubMed1996

Site-specific phosphorylation of IkappaBalpha by a novel ubiquitination-dependent protein kinase activity.

Signal-induced activation of the transcription factor NF-kappaB requires specific phosphorylation of the inhibitor IkappaBalpha and its subsequent proteolytic degradation. Phosphorylation of serine residues 32 and 36 targets IkappaBalpha to the ubiquitin (Ub)-proteasome pathway. Here we report the identification of a large, multisubunit kinase (molecular mass approximately 700 kDa) that phosphorylates IkappaBalpha at S32 and S36. Remarkably, the activity of this kinase requires the Ub-activating enzyme (E1), a specific Ub carrier protein (E2) of the Ubc4/Ubc5 family, and Ub. We also show that a ubiquitination event in the kinase complex is a prerequisite for specific phosphorylation of IkappaBalpha. Thus, ubiquitination serves a novel regulatory function that does not involve proteolysis.

Binding Sites↗

PubMed1996

Identification of a second transmembrane protein tyrosine phosphatase, IA-2beta, as an autoantigen in insulin-dependent diabetes mellitus: precursor of the 37-kDa tryptic fragment.

A novel cDNA, IA-2beta, was isolated from a mouse neonatal brain library. The predicted protein sequence revealed an extracellular domain, a transmembrane region, and an intracellular domain. The intracellular domain is 376 amino acids long and 74% identical to the intracellular domain of IA-2, a major autoantigen in insulin-dependent diabetes mellitus (IDDM). A partial sequence of the extracellular domain of IA-2beta indicates that it differs substantially (only 26% identical) from that of IA-2. Both molecules are expressed in islets and brain tissue. Forty-six percent (23 of 50) of the IDDM sera but none of the sera from normal controls (0 of 50) immunoprecipitated the intracellular domain of IA-2beta. Competitive inhibition experiments showed that IDDM sera have autoantibodies that recognize both common and distinct determinants on IA-2 and IA-2beta. Many IDDM sera are known to immunoprecipitate 37-kDa and 40-kDa tryptic fragments from islet cells, but the identity of the precursor protein(s) has remained elusive. The current study shows that treatment of recombinant IA-2beta and IA-2 with trypsin yields a 37-kDa fragment and a 40-kDa fragment, respectively, and that these fragments can be immunoprecipitated with diabetic sera. Absorption of diabetic sera with unlabeled recombinant IA-2 or IA-2beta, prior to incubation with radiolabeled 37-kDa and 40-kDa tryptic fragments derived from insulinoma or glucagonoma cells, blocks the immunoprecipitation of both of these radiolabeled tryptic fragments. We conclude that IA-2beta and IA-2 are the precursors of the 37-kDa and 40-kDa islet cell autoantigens, respectively, and that both IA-2 and IA-2beta are major autoantigens in IDDM.

Amino Acid Sequence↗

PubMed1996

Interferon-gamma induced cell death in a cultured human salivary gland cell line.

Increased levels of several cytokines, including interferon-gamma (IFN-gamma) and tumor necrosis factor-alpha (TNF-alpha), have been demonstrated in the salivary gland microenvironment of patients with Sjögren's syndrome (SS). How these cytokines may be contributing to the pathogenesis of the disease is not well understood. This study examined the role of IFN-gamma +/- TNF-alpha on cellular death in a cultured human salivary gland cell line (HSG). Cells treated long-term with IFN-gamma +/- TNF-alpha demonstrate a profound antiproliferative effect with a decrease in cell number to below that initially plated. Treatment of HSG cells with TNF-alpha alone did not have any significant effects on growth but did increase the expression of the IFN-gamma receptor. Cells labelled with propidium iodide and anti-digoxigenin dUTP/dATP were examined by flow cytometry to determine the percentage of cells exhibiting low DNA content and DNA strand breaks. The percentage of cells exhibiting subdiploid DNA and DNA strand breaks increased with increased time of exposure to the cytokines. The maximum percentage of cells exhibiting DNA degradation at 12 days was 58% for cells treated with IFN-gamma + TNF-alpha, 31% for IFN-gamma treated cells, and < 5% for TNF-alpha-treated and untreated cells. The cells with subdiploid ( < 2n) DNA were subsequently demonstrated to represent two populations, both with evidence of increased DNA strand breaks but with differing light scatter characteristics. One population had features of cells undergoing necrosis, whereas the second population exhibited features of apoptosis. These findings were confirmed by transmission electron microscopy. Cells not exposed to cytokines did not exhibit significant evidence of either death process. We conclude that long-term exposure of a human salivary gland epithelial cell line to IFN-gamma +/- TNF-alpha leads to increased DNA degradation and subsequent cell death. This suggests a potential SS disease mechanism and implicates the role of the epithelial cell in this disease as an important area for future study.

Cell Count↗

PubMed1996

Polyreactive antigen-binding B cells in the peripheral circulation are IgD+ and B7-.

Polyreactive antibodies are naturally occurring antibodies, primarily of the IgM isotype, that are capable of reacting with a wide variety of different self and non-self antigens. Previously, we reported that a B cell capable of making polyreactive antibody has Ig receptors on its surface that can bind different antigens. The present investigation was initiated to characterize these polyreactive antigen-binding B cells further. A panel of fluorescein isothiocyanate-labeled antigens (insulin, IgG Fc fragment or beta-galactosidase) served as probes to select polyreactive antigen-binding B cells by cell sorting. Our experiment revealed that these polyreactive antigen-binding B cells were mainly of the IgD isotype. They expressed high levels of CD40 and major histocompatibility complex class II molecules, but little or no B7-1, B7-2, or Fas. In contrast to the binding of antigens to monoreactive receptors (usually high affinity), the binding of antigens to polyreactive receptors (usually moderate or low affinity) did not up-regulate the expression of B7-1 or B7-2. Antigens that bound to polyreactive receptors, however, were internalized and degraded, although not as efficiently as antigens that bound to monoreactive receptors. Despite the ability of these B7- cells to process antigens, they were not able to activate T cells in a mixed leukocyte reaction. It is concluded that polyreactive antigen-binding B cells have properties that are consistent with the ability to induce immunological tolerance.

Antibody-Producing Cells↗

PubMed1996

Nuclear magnetic resonance studies of lipid hydration in monomethyldioleoylphosphatidylethanolamine dispersions.

Solid-state proton nuclear magnetic resonance has been used to examine surface hydration in suspensions of monomethyldioleoylphosphatidylethanolamine (MeDOPE). The magic-angle spinning (MAS) 1H spectra for aqueous suspensions of MeDOPE in the L alpha phase exhibited two resonances of roughly equal intensity that could be ascribed to water protons, but both their spin-lattice relaxation times and chemical shifts converged upon conversion to the hexagonal phase. Only a single water peak was observed for analogous samples of dioleoylphosphatidylcholine (DOPC). MAS-assisted two-dimensional nuclear Overhauser effect spectroscopy (NOESY) was conducted for multibilayers of both MeDOPE and DOPC. Through-space interactions were identified between pairs of lipid protons, as expected from their chemical structure. For lamellar suspensions of MeDOPE, positive NOESY cross-peaks were observed between the downfield-shifted water resonance (only) and both CH2N and NH2CH3+ protons of the lipid headgroup. These cross-peaks were not observed in the NOESY spectra of MeDOPE in its hexagonal or cubic phases or for lamellar DOPC reference samples. Taken together, the observation of two water peaks, spin-lattice relaxation behavior, and NOESY connectivities in MeDOPE suspensions support the interpretation that the low-field water peak corresponds to hydrogen-bonded interlamellar water interacting strongly with the lipid. Such a population of water molecules exists in association with MeDOPE in the lamellar phase but not for its inverted phases or for lamellar dispersions of DOPC.

Biophysical Phenomena↗

PubMed1996

The microcirculation and survival of experimental flow-through venous flaps.

The subject of venous flaps is controversial. The purpose of this study was to investigate the haemodynamic changes and the survival process of venous flow-through flaps. Venous flaps and composite grafts were elevated along the axis of the thoracoepigastric veins in rabbits. The microcirculation was studied by capillaroscopy and injection studies. For the first 72 h, the flaps were nourished by venous blood; venous blood flowed slowly from the principal vein to its tributary veins and then through venous anastomoses to reach other tributary veins. No backflow from venules into capillaries was seen. New vessels began to grow into the flaps from 72 h postoperatively. Four days postoperatively, arterial flow with low velocity was seen in the primary flap arteries and the backflow of venous blood disappeared. Seven days postoperatively, the abnormal flow in "unphysiological" channels was replaced by normal flow in "physiological" channels. Six weeks postoperatively, the vessel structure of venous flaps was the same as that of normal skin. These results suggest that the profuse venous network in venous flaps and early invasion of new blood vessels are the mainstays of venous flap survival.

Animals↗

PubMed1996

Evaluating spin diffusion in MAS-NOESY spectra of phospholipid multibilayers.

Biological semisolids such as aqueous phospholipid dispersions are amenable to experiments that combine magic-angle spinning (MAS) to yield high-resolution 1H NMR-spectra and two-dimensional nuclear Overhauser spectroscopy (NOESY) to estimate proton-proton distances. Using several selectively deuterated dimyristoylphosphatidylcholines, a systematic investigation has been made into the origin of an anomalous NOESY crosspeak between methyl groups of the lipid headgroup and the acyl chains. Although the spin-relaxation and line-narrowing behavior in these multilamellar systems argue against efficient spin diffusion, interdigitated or chain-bendback structural models that bring these 1H nuclei into close proximity are not implicated by the MAS-NOESY results for this phospholipid system. A mechanism has been proposed for spin communication between the two types of methyl protons within a conventional lipid bilayer structure: through-space interactions link the headgroup and backbone protons on adjacent molecules, and then spin diffusion occurs along the acyl chains.

Chemical Phenomena↗

PubMed1996

Interferon-gamma induces persistent depletion of internal Ca2+ stores in a human salivary gland cell line.

Interferon-gamma (IFN-gamma), in the presence of tumor necrosis factor-alpha (TNF-alpha), decreases proliferation of a human salivary gland ductal cell line, HSG (Wu, A., R. Kurrasch, J. Katz, P. Fox, B. Baum, and J. Atkinson. J. Cell. Physiol. 161:217-226, 1994). We examined the possible effects of these cytokines (1,000 U/ml IFN-gamma +/- 20 U/ml TNF-alpha for 7 days) on Ca2+ mobilization in HSG cells. In HSG cells, fetal bovine serum (10%) or carbachol (100 microM) stimulated rapid increases in cytosolic Ca2+ concentration ([Ca2+]i), apparently mobilized from different thapsigargin-sensitive intracellular Ca2+ stores. Serum induced a proliferative effect on HSG cells, which was suppressed (> 90%) by treatment with IFN-gamma +/- TNF-alpha, but not with TNF-alpha alone. Serum-, carbachol-, and thapsigargin-stimulated [Ca2+]i elevations were reduced by 90, 60, and > 65%, respectively, in cells treated with IFN-gamma +/- TNF-alpha and 30, 45, and 45%, respectively, in cells treated with TNF-alpha. Removal of the cytokines from the growth medium induced recovery of both cell proliferation and Ca2+ mobilization responses within 7 days. Treatment of HSG cells with thapsigargin (0.02-2 nM) induced a dose-dependent decrease in cell proliferation. Additionally, acute treatment (< 10 min) of cells with IFN-gamma did not affect [Ca2+]i or alter carbachol-, thapsigargin-, or serum-induced changes in [Ca2+]i. These data demonstrate that prolonged treatment of HSG cells with IFN-gamma +/- TNF-alpha leads to a persistent depletion of intracellular Ca2+ stores. We suggest that this may have a role in cell growth.

Blood Physiological Phenomena↗

PubMed1996

Highly virulent strains of herpes simplex virus fail to kill mice following infection via gingival route.

Virulence of herpes simplex virus (HSV) in mice has been demonstrated to be dependent on the site of infection. In this experiment, pathogenesis of HSV was studied in 2 different routes of infection in a mouse model system. When BALB/c mice were infected with 5 x 10(3) plaque-forming units (PFU) of virulent HSV type 1 Miyama GC+ strain (HSV-1-GC+) intraperitoneally, all mice were dead in 6 to 9 days. HSV-1-GC+ was recovered from organs such as the cerebrum, cerebellum, brainstem, and spleen 2 to 5 days after infection, but not from other organs such as trigeminal ganglia. However, if mice were infected in the maxillary gingiva with 1.0 x 10(7) PFU of HSV-1-GC+, all mice survived. HSV-1-GC+ was recovered from the trigeminal ganglia and brainstem 2 to 5 days after infection, but not from other organs tested. When mice were infected in maxillary gingiva with HSV-1-GC+, followed by the intraperitoneal injection of 6 mg of cyclophosphamide 72 hrs after virus infection, all mice were dead within days. Immunofluorescent and hematoxylin-eosin staining of gingival tissue sections revealed that when mice were infected in maxillary gingiva with HSV-1-GC+, 3 times as many gamma delta T-cells and 5 times as many polymorphonuclear cells can be detected in sections of maxillary gingiva when compared with non-infected mice. These data show that the gingiva of mice is considerably more resistant to infection with HSV, compared with the peritoneal cavity, and suggest the possible presence of an oral defense mechanism which might be different from that in the peritoneal cavity.

Animals↗