Experimental rhinovirus 16 infection increases intercellular adhesion molecule-1 expression in bronchial epithelium of asthmatics regardless of inhaled steroid treatment

BACKGROUND: Rhinovirus infections in airway epithelial cells in vitro have been shown to upregulate intercellular adhesion molecule-1 (ICAM-1) expression. Epithelial ICAM-1, in its dual role as the major rhinovirus receptor and as adhesion molecule for inflammatory cells may be involved in the pathogenesis of rhinovirus-induced exacerbations of asthma. OBJECTIVE: We aimed to investigate the effect of experimental rhinovirus 16 (RV16) infection on ICAM-1 expression in bronchial mucosal biopsies in asthma. In addition, the effect of 2 weeks pretreatment with inhaled budesonide (800 microg b.d.) on RV16-associated changes in ICAM-1 expression was studied. METHODS: The study had a parallel, placebo-controlled design in 25 steroid-naive nonsmoking atopic asthmatic subjects. After 2 weeks budesonide (BUD) or placebo (PLAC) pretreatment bronchoscopy was performed 2 days before (day -2) and 6 days after (day 6) RV16 inoculation (on days 0 and 1). Immunohistochemical staining for ICAM-1 was performed on snap-frozen bronchial biopsies. ICAM-1 staining intensity on the basal epithelial cells was scored semiquantitatively from 1 (weak) to 3 (intense). Similarly, epithelial intactness was noted (1 = basal cells only, 2 = basal and parabasal cells, 3 = intact epithelium). RESULTS: ICAM-1 scores were not significantly different between the groups at day -2 (P > or = 0.08). Subsequent RV16 infection was associated with a trend towards an increase in ICAM-1 expression in the BUD-group (P = 0.07), whereas the increase was significant in the PLAC-group (P = 0.03). However, the increase was not significantly different between the groups (P = 0.74). Epithelial intactness score was not different between the groups before RV16 infection (P > or = 0.07), and no significant changes were observed in either group (P > or = 0.59). Moreover, ICAM-1 score did not correlate significantly with epithelium score in either group, at any time-point (P > or = 0.27). CONCLUSION: We conclude that an RV16 common cold in atopic asthmatic subjects is associated with increased ICAM-1 expression in the bronchial epithelium, which is not related to epithelial intactness. Glucocorticoid treatment does not appear to prevent the RV16-associated increased ICAM-1 expression. This suggests that other treatment modalities are required to protect against the spreading of infection during rhinovirus-induced exacerbations in asthma.     

Interferon-gamma enhances rhinovirus-induced RANTES secretion by airway epithelial cells

Respiratory viruses, including rhinoviruses, infect respiratory epithelium and induce a variety of cytokines and chemokines that can initiate an inflammatory response. Cytokines, such as interferon (IFN)-gamma and tumor necrosis factor (TNF)-alpha, could enhance epithelial cell activation by inducing virus receptors. To test this hypothesis, effects of IFN-gamma or TNF-alpha on expression of intercellular adhesion molecule (ICAM)-1, rhinovirus binding, and virus-induced chemokine secretion on A549 and human bronchial epithelial cells (HBEC) were determined. The results varied with the type of cell. IFN-gamma was a stronger inducer of ICAM-1 and viral binding on HBEC, whereas TNF-alpha had greater effects on A549 cells. In addition, IFN-gamma, but not TNF-alpha, synergistically enhanced regulated on activation, normal T cells expressed and secreted (RANTES) mRNA expression and protein secretion induced by RV16 or RV49. To determine whether IFN-gamma could enhance RANTES secretion independent of effects on ICAM-1 and RV binding, HBEC were transfected with RV16 RNA in the presence or absence of IFN-gamma. RV16 RNA alone stimulated RANTES secretion, and this effect was enhanced by IFN-gamma. These results demonstrate that IFN-gamma can enhance rhinovirus-induced RANTES secretion by increasing viral binding, and through a second receptor-independent pathway. These findings suggest that IFN-gamma, by upregulating RANTES secretion, could be an important regulator of the initial immune response to rhinovirus infections.     

Rhinovirus replication causes RANTES production in primary bronchial epithelial cells.

The mechanisms by which rhinovirus (RV) infections produce lower airway symptoms in asthmatic individuals are not fully established. To determine effects of RV infection on lung epithelial cells, primary human bronchial epithelial (BE) cells were infected with either RV16 or RV49, and viral replication, cell viability, and cell activation were measured. Both viral serotypes replicated in BE cells at 33 degrees C (DeltaTCID50 / ml = 2 to 2.5 log units) and at 37 degrees C (DeltaTCID50 /ml = 1.6 log units), but only high doses of RV49 (10(6) TCID50 /ml) caused cytopathic effects and reduced cell viability. In addition, regulated on activation, normal T cells expressed and secreted (RANTES) secretion was increased in epithelial cells infected with RV16 or RV49 (243 and 398 pg/ml versus 13 pg/ml uninfected control cells), and a similar pattern was seen for RANTES messenger RNA. RV infection also caused increased secretion of interleukin-8 and granulocyte macrophage colony-stimulating factor, but did not alter expression of either intercellular adhesion molecule-1 or human leukocyte-associated antigen-DR. These observations suggest that RVs can replicate in lower airway cells in vivo, and support epidemiologic studies that link RV with lower respiratory illnesses. Further, RV-induced secretion of RANTES and other cytokines could trigger antiviral immune responses in vivo, but these effects could also contribute to the pathogenesis of respiratory symptoms in subjects with asthma.     

Rhinovirus elicits proasthmatic changes in airway responsiveness independently of viral infection

BACKGROUND: Rhinovirus (RV), the principal pathogen responsible for the common cold, is importantly implicated in triggering attacks of asthma secondary to changes in airway responsiveness. OBJECTIVE: Because the airway histopathologic features of RV infection are relatively modest, we tested the hypothesis that RV can directly elicit proasthmatic-like changes in airway smooth muscle (ASM) responsiveness independently of actual viral infection and its associated cytopathic effects. METHODS: Isolated ASM tissues and cultured ASM cells were inoculated with either infectious or noninfectious (UV-irradiated) RV16 and RV2, the latter serotypes belonging to the "major" and "minor" groups of RV subtypes, respectively. ASM constrictor and relaxant responsiveness, G(i) protein expression, and proinflammatory cytokine release were subsequently compared under the different treatment conditions. RESULTS: In contrast to RV2, which had no effect, RV16 inoculation elicited enhanced ASM contractility and impaired relaxation to cholinergic and beta-adrenergic agonists, respectively, in association with increased ASM membrane G(i) protein expression and induced release of the proinflammatory cytokines IL-5 and IL-1beta. These proasthmatic-like effects were also observed in ASM exposed to UV-irradiated RV16, wherein viral replication was completely inhibited. In contrast, pretreatment of ASM with a neutralizing antibody directed against ICAM-1, the host receptor for the "major" group of RVs, completely abrogated the proasthmatic effects of RV16. CONCLUSIONS: The results demonstrate that (1) RV16 elicits proasthmatic changes in ASM responsiveness that can occur independently of actual viral infection of the ASM and (2) the effects of RV16 are attributed solely to binding of the virus to its host receptor (ICAM-1) on the ASM cell surface. Collectively, these findings support the notion that RV-induced exacerbation of wheezing in asthmatic individuals can occur even in the absence of any cytopathology associated with viral infection.     

Oral squamous cell carcinoma is associated with decreased bcl-2/bax expression ratio and increased apoptosis.

Expression of bcl-2 and bax and apoptosis were studied in fresh frozen samples of normal oral epithelium (OE, n = 7) and oral squamous cell carcinomas (OSCC, n = 16) by immunohistochemistry and the TUNEL method. In OE, bcl-2 was expressed in both basal (96.6% +/- 2.3% [mean +/- SD]) and suprabasal (91.8% +/- 6.2%) compartments. In OSCC, compared with OE, there was a marked reduction of bcl-2-positive cells in the basal part, and in the central parts of well-differentiated (33.0% +/- 19.7%, P < .001) and moderately differentiated (6.1% +/- 4.6%, P < .001) and also in poorly differentiated (1.9% +/- 0.2%, P < .001) tumors. More cells expressed bax in the suprabasal layer of OE (65.6% +/- 9.9%) and central parts of OSCC than in the basal layer of OE (19.1% +/- 4.1%) and basal parts of OSCC. A higher proportion of cells expressed bax in the central part of well-differentiated OSCC (74.3% +/- 8.2%) than in poorly differentiated OSCC (24.9% +/- 9.7%, P < .001). Apoptotic cell death was more pronounced in OSCC (1.5% +/- 0.9%) than in OE (0.4% +/- 0.1%, P < .05). We conclude that, in OSCC, compared with OE, there is a decreased bcl-2 expression, a lowered bcl-2/bax ratio and increased apoptosis. The expression of bax correlates with histological tumor grading in oral squamous cell carcinoma.     

Membrane vesicles released by intestinal epithelial cells infected with rotavirus inhibit T-cell function

Rotavirus (RV) predominantly replicates in intestinal epithelial cells (IEC), and "danger signals" released by these cells may modulate viral immunity. We have recently shown that human model IEC (Caco-2 cells) infected with rhesus-RV release a non-inflammatory group of immunomodulators that includes heat shock proteins (HSPs) and TGF-β1. Here we show that both proteins are released in part in association with membrane vesicles (MV) obtained from filtrated Caco-2 supernatants concentrated by ultracentrifugation. These MV express markers of exosomes (CD63 and others), but not of the endoplasmic reticulum (ER) or nuclei. Larger quantities of proteins associated with MV were released by RV-infected cells than by non-infected cells. VP6 co-immunoprecipitated with CD63 present in these MV, and VP6 co-localized with CD63 in RV-infected cells, suggesting that this viral protein is associated with the MV, and that this association occurs intracellularly. CD63 present in MV preparations from stool samples from 36 children with gastroenteritis due or not due to RV were analyzed. VP6 co-immunoprecipitated with CD63 in 3/8 stool samples from RV-infected children, suggesting that these MV are released by RV-infected cells in vivo. Moreover, fractions that contained MV from RV-infected cells induced death and inhibited proliferation of CD4(+) T cells to a greater extent than fractions from non-infected cells. These effects were in part due to TGF-β, because they were reversed by treatment of the T cells with the TGF-β-receptor inhibitor ALK5i. MV from RV-infected and non-infected cells were heterogeneous, with morphologies and typical flotation densities described for exosomes (between 1.10 and 1.18?g/mL), and denser vesicles (>1.24?g/mL). Both types of MV from RV-infected cells were more efficient at inhibiting T-cell function than were those from non-infected cells. We propose that RV infection of IEC releases MV that modulate viral immunity.     

Modulation of the epithelial inflammatory response to rhinovirus in an atopic environment

Background Immune responses to rhinovirus (RV) as well as direct effects of RV on respiratory epithelium may contribute to the induction of asthma exacerbations. Objective To evaluate the effect of the environment resulting from an atopic immune response on RV‐induced epithelial inflammation, replication and cytotoxicity. Methods Peripheral blood mononuclear cells (PBMC) from atopic asthmatic subjects and matched controls (12 pairs) were isolated and stimulated by RVs. Human bronchial epithelial (BEAS‐2B) cells were infected with RV in the presence of conditioned media from RV‐stimulated PBMC cultures. IL‐6, IL‐8, RANTES and TGF‐β1 levels were measured by ELISA, RV‐induced cytotoxicity by a colorimetric method and RV titres on Ohio‐HeLa cells. Results RV‐induced epithelial production of IL‐6, IL‐8 and RANTES was significantly lower, while TGF‐β1 was higher when cells were exposed to conditioned media from atopic asthmatic subjects compared with those from normal controls. Exposure to the ‘atopic’ environment also resulted in elevated RV titres and increased RV‐induced cytotoxicity. Conclusions Under the influence of an atopic environment, the epithelial inflammatory response to RV is down‐regulated, associated with increased viral proliferation and augmented cell damage, while TGF is up‐regulated. These changes may help explain the propensity of atopic asthmatic individuals to develop lower airway symptoms after respiratory infections and indicate a mechanism through which viral infections may promote airway remodelling.     

Allergenic proteases cleave the chemokine CX3CL1 directly from the surface of airway epithelium and augment the effect of rhinovirus

CX3CL1 has been implicated in allergen-induced airway CD4⁺ T-lymphocyte recruitment in asthma. As epidemiological evidence supports a viral infection–allergen synergy in asthma exacerbations, we postulated that rhinovirus (RV) infection in the presence of allergen augments epithelial CX3CL1 release. Fully differentiated primary bronchial epithelial cultures were pretreated apically with house dust mite (HDM) extract and infected with rhinovirus-16 (RV16). CX3CL1 was measured by enzyme-linked immunosorbent assay and western blotting, and shedding mechanisms assessed using inhibitors, protease-activated receptor-2 (PAR-2) agonist, and recombinant CX3CL1-expressing HEK293T cells. Basolateral CX3CL1 release was unaffected by HDM but stimulated by RV16; inhibition by fluticasone or GM6001 implicated nuclear factor-κB and ADAM (A Disintegrin and Metalloproteinase) sheddases. Conversely, apical CX3CL1 shedding was stimulated by HDM and augmented by RV16. Although fluticasone or GM6001 reduced RV16+HDM-induced apical CX3CL1 release, heat inactivation or cysteine protease inhibition completely blocked CX3CL1 shedding. The HDM effect was via enzymatic cleavage of CX3CL1, not PAR-2 activation, yielding a product mitogenic for smooth muscle cells. Extracts of Alternaria fungus caused similar CX3CL1 shedding. We have identified a novel mechanism whereby allergenic proteases cleave CX3CL1 from the apical epithelial surface to yield a biologically active product. RV16 infection augmented HDM-induced CX3CL1 shedding—this may contribute to synergy between allergen exposure and RV infection in triggering asthma exacerbations and airway remodeling.     

S100P expression in human esophageal epithelial cells: Human esophageal epithelial cells sequentially produce different S100 proteins in the process of differentiation

Extracellular calcium ions (Ca(2+)) are important in regulating the differentiation of keratinocytes and squamous epithelial cells. To clarify the mechanisms involved in the differentiation of human esophageal epithelial cells (EECs), we used the primary culture of human EECs, which can be differentiated by increasing the concentration of extracellular Ca(2+), and tried to reveal the extracellular Ca(2+) inducible genes using a differential display (DD) method. We found that the calcium-binding protein S100P showed a Ca(2+)-inducible expression in the EECs. Our immunohistochemical study demonstrated that differentiated large EECs expressing S100P overlie immature proliferating cells which lack S100P immunoreactivity. S100P was detected in vivo in the suprabasal layers of the epithelium. These findings indicate that S100P expression is closely associated with differentiation of human EECs. We also investigated the expression of other S100 proteins, including S100A2, S100A6, and CAAF1 (S100A12), in human EECs. Most of the immature EECs were positive for S100A2 and S100A6, whereas the S100A12-producing cells were similar to the S100P-producing cells. In vivo, S100A12 was strongly detected on all epithelial cells except for basal and proliferating cells. S100A2 was detected on all of the epithelial cells. S100A6 was preferentially seen in the cells of basal layers. These findings suggest that within EECs S100 proteins might play important roles in cell differentiation during specific stages. Among them, S100P expression is unique in that this protein is transiently expressed during the early stage of differentiation.     

Expression of intercellular adhesion molecule‐1 (ICAM‐1) in nasal epithelial cells of atopic subjects: a mechanism for increased rhinovirus infection?

Since clinical experimental studies indicate that upper respiratory tract viral infections may exacerbate acute asthma symptoms in atopic/asthmatic individuals, we have investigated the expression and modulation of ICAM-1 on human nasal epithelial cells (HNEC) from normal and atopic subjects. ICAM-1 is the attachment molecule for the majority of serotypes of human rhinovirus (HRV), including HRV-14, and is also critical for the migration and activation of immune effector cells. Basal ICAM-1 expression was significantly higher in HNEC obtained by brushings from atopic compared with non-atopic subjects (P = 0.031), and was also significantly increased on atopic HNEC harvested in season compared with out of season (P < 0.05). Atopic HNEC showed further up-regulation in ICAM-1 expression when cultured with clinically relevant allergen (P = 0.032). ICAM-1 levels on normal HNEC were also increased by infection with HRV-14 (P < 0.05). Basal expression of ICAM-1 on atopic nasal polyp epithelial cells (EC) was significantly higher than on both normal and atopic nasal HNEC. This elevated nasal polyp ICAM-1 level was not increased further by allergen, although HRV infection resulted in a small significant increase. Recovered viral titres from HRV-infected nasal polyp EC were 1.5-fold higher than from infected normal nasal HNEC. The data are consistent with the hypothesis that allergen, by enhancing expression of the HRV attachment target on host cells, facilitates viral infection in atopic subjects; simultaneously HRV-induced increases in ICAM-1 levels would favour migration and activation of immune effector cells to the airway, resulting in enhanced atopic inflammation.     

Epithelial hyperproliferation and transglutaminase 1 gene expression in Stevens-Johnson syndrome conjunctiva

In Stevens-Johnson syndrome, pathological keratinization of the ordinarily nonkeratinized corneal and conjunctival mucosal epithelia results in severe visual loss. We examined conjunctiva covering cornea in five eyes in the chronic cicatricial phase of Stevens-Johnson syndrome. Normal conjunctiva from five age-matched individuals was studied also. The number of epithelial cells in Stevens-Johnson syndrome conjunctiva that were immunoreactive with a monoclonal antibody, Ki-67, to a nuclear antigen found only in proliferating cells was greater than normal (93.8+/-19.8 cells above 100 basal cells versus 12.8+/-0.5 cells above 100 basal cells; P = 0.009). In addition, although clinical inflammation was mild, massive lymphocytic infiltration was seen in the substantia propria of conjunctiva covering cornea. In situ hybridization documented transglutaminase 1 (keratinocyte transglutaminase) mRNA in suprabasal cells of the abnormally thickened conjunctival epithelium in all Stevens-Johnson syndrome patients. In contrast, no message was detected in normal conjunctival or corneal epithelia. Transglutaminase 1 is expressed during the terminal differentiation of keratinocytes where it helps synthesize cornified cell envelopes. We speculate that in Stevens-Johnson syndrome, epithelial hyperproliferation, and transglutaminase 1 gene expression lead to the pathological keratinization of ocular surface mucosal epithelia.     

Inhibition of adhesion molecules by budesonide on a human epithelial cell line (lung carcinoma)

Inhaled corticosteroids in the treatment of asthma have been shown to produce marked reductions in the number of inflammatory cells (mainly mast cells and eosinophils) and their products at bronchial level (such as cytokines). Recently, it has been demonstrated that epithelial cells express ICAM-1/CD54 in allergic patients both during natural allergen exposure and after allergen challenge. We have previously demonstrated that deflazacort (a systemic steroid) reduces the expression of ICAM-1 on conjunctival epithelial cells. The present study aimed to evaluate the effects exerted by budesonide on adhesion molecule expression by a human epithelial cell line (lung carcinoma: DM) and on soluble ICAM-1. Budesonide was added at concentrations corresponding to 10⁻⁸, 10⁻⁷, and 10⁻⁶ mol/1 in cultured epithelial cells, either in the absence of any stimulus or in the presence of interferon-gamma (IFN-y) at 500 U/ml. After 24 h of incubation, cytofluorometric analysis was performed for ICAM-1 and CD29/VLAP1. The 24–h supernatants of the same cultures were collected and then evaluated for soluble ICAM-1 (sICAM-1). The results showed that budesonide inhibits ICAM-1 and CD29 basal expression on the cells studied (P<0.05): budesonide was effective in a dose-dependent manner. In addition, budesonide reduced surface ICAM-1 upregulation induced by IFN-γ at 500 U/ml (p<0.05). Finally, cell cultures with budesonide showed decreased levels of soluble ICAM-1 in basal condition, but not after IFN-γ stimulation.     

Nontypeable Haemophilus influenzae adheres to intercellular adhesion molecule 1 (ICAM-1) on respiratory epithelial cells and upregulates ICAM-1 expression

Nontypeable Haemophilus influenzae (NTHI) is an important respiratory pathogen. NTHI initiates infection by adhering to the airway epithelium. Here, we report that NTHI interacts with intracellular adhesion molecule 1 (ICAM-1) expressed by respiratory epithelial cells. A fourfold-higher number of NTHI bacteria adhered to Chinese hamster ovary (CHO) cells transfected with human ICAM-1 (CHO-ICAM-1) than to control CHO cells (P < or = 0.005). Blocking cell surface ICAM-1 with specific antibody reduced the adhesion of NTHI to A549 respiratory epithelial cells by 37% (P = 0.001) and to CHO-ICAM-1 cells by 69% (P = 0.005). Preincubating the bacteria with recombinant ICAM-1 reduced adhesion by 69% (P = 0.003). The adherence to CHO-ICAM-1 cells of NTHI strains deficient in the adhesins P5, P2, HMW1/2, and Hap or expressing a truncated lipooligosaccharide was compared to that of parental strains. Only strain 1128f-, which lacks the outer membrane protein (OMP) P5-homologous adhesin (P5 fimbriae), adhered less well than its parental strain. The numbers of NTHI cells adhering to CHO-ICAM-1 cells were reduced by 67% (P = 0.009) following preincubation with anti-P5 antisera. Furthermore, recombinant ICAM bound to an OMP preparation from strain 1128f+, which expresses P5, but not to that from its P5-deficient mutant, confirming a specific interaction between ICAM-1 and P5 fimbriae. Incubation of respiratory epithelial cells with NTHI increased ICAM-1 expression fourfold (P=0.001). Adhesion of NTHI to the respiratory epithelium, therefore, upregulates the expression of its own receptor. Blocking interactions between NTHI P5 fimbriae and ICAM-1 may reduce respiratory colonization by NTHI and limit the frequency and severity of NTHI infection.     

Rhinovirus and asthma

Rhinoviruses (RVs) cause the majority of common colds, which often provoke wheezing in patients with asthma. The precise mechanisms responsible for the RV infection-induced exacerbations of bronchial asthma are still uncertain. However, several reports reveal airway hyperresponsiveness, increases in chemical mediators in airway secretions such as kinin and histamine, and airway inflammation in patients with bronchial asthma after RV infection. RV infection induces an accumulation of inflammatory cells in airway mucosa and submucosa including neutrophils, lymphocytes and eosinophils. RV affects the barrier function of airway epithelial cells, and activates the airway epithelial cells and other cells in the lung to produce pro-inflammatory cytokines, including various kinds of interleukins, GM-CSF and RANTES, and histamine. RV also stimulates the expression of intercellular adhesion molecule-1 (ICAM-1) and low-density lipoprotein receptors in the airway epithelium, receptors for major and minor RVs. On the other hand, RV infection is inhibited by treatment with soluble ICAM-1, and by reduction of ICAM-1 expression in the airway epithelial cells after treatment with erythromycin. Both soluble ICAM-1 and erythromycin were reported to reduce the frequency of common colds. Here, we review the pathogenesis and management of RV infection-induced exacerbation of bronchial asthma.     

Synergistic inhibition of HIV-1 in activated and resting peripheral blood mononuclear cells, monocyte-derived macrophages, and selected drug-resistant isolates with nucleoside analogues combined with a natural product, resveratrol

Resveratrol (trans-3,5,4;-trihydroxystilbene) is a phytoalexin present in grapes, wine, and certain plants, which has recently been reported to possess properties that may protect against atherosclerosis, certain cancers, and inflammation. We now report that resveratrol (RV) synergistically enhances the anti-HIV-1 activity of the nucleoside analogues zidovudine (AZT), zalcitabine (ddC), and didanosine (ddI). RV at 10 microM was not toxic to cells, and by itself reduced viral replication by 20% to 30%. In phytohemagglutinin (PHA)-activated peripheral blood mononuclear cells (PBMCs) infected with HTLV-IIIB, 10 microM RV reduced the 90 % inhibitory concentration (IC90) of AZT, ddC, and ddI by 3.5-, 5.5-, and 17.8-fold, respectively. Similar antiviral activity was demonstrated when ddI was combined with 5 or 10 mM RV in PBMCs infected with clinical isolates of HIV-1. The addition of RV resulted in a >10-fold augmentation of ddI-antiviral activity in infected monocyte-derived macrophages (MDMs). In a resting cell model of T lymphocytes which were infected with HTLV-IIIB, RV plus ddI in combination, but not individually, suppressed establishment of a productive viral infection. In addition, RV plus ddI markedly inhibited the replication of four ddI-resistant viral isolates, three of which presented mutations in the RT gene conferring RT-multidrug resistance. Finally, when compared with hydroxyurea (HU), both 100 mM HU and 10 mM RV showed similar enhancement of ddI-antiviral suppressive activity. However, RV was shown to have less of a cellular antiproliferative effect than HU.     

Intestinal epithelia activate anti-viral signaling via intracellular sensing of rotavirus structural components

Rotavirus (RV), a leading cause of severe diarrhea, primarily infects intestinal epithelial cells (IECs) causing self-limiting illness. To better understand innate immunity to RV, we sought to define the extent to which IEC activation of anti-viral responses required viral replication or could be recapitulated by inactivated RV or its components. Using model human intestinal epithelia, we observed that RV-induced activation of signaling events and gene expression typically associated with viral infection was largely mimicked by administration of ultraviolet (UV)-inactivated RV. Use of anti-interferon (IFN) neutralizing antibodies revealed that such replication-independent anti-viral gene expression required type I IFN signaling. In contrast, RV-induction of nuclear factor-κB-mediated interleukin-8 expression was dependent on viral replication. The anti-viral gene expression induced by UV-RV was not significantly recapitulated by RV RNA or RV virus-like particles although the latter could enter IEC. Together, these results suggest that RV proteins mediate viral entry into epithelial cells leading to intracellular detection of RV RNA that generates an anti-viral response.     

Evidence for restricted replication of rubella virus in rat glial cells in culture

Intracellular rubella virus (RV) polypeptide synthesis during a productive infection of murine fibroblasts (L2 cells) has been investigated using immune precipitation techniques. Four structural and three additional intracellular polypeptides (p75, p60, VP44, VP41, p30, VP24, and VP19) were observed following polyacrylamide slab gel electrophoresis and autoradiography. However, when normal rat glial (RG) cells were infected only five polypeptides could be observed (p75, p60, VP44, VP41, and VP19). No infectious RV could be detected in tissue culture medium from flasks of infected RG cells. Calculations of relative concentrations of intracellular RV polypeptides precipitated from L2 and RG cells indicated that undetectable amounts of p30 and VP24, diminished amounts of p60 and VP19 and more than twice as much p75 were precipitated from infected RG cells. These data indicate that there is restricted replication of RV in normal rat glia.