bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nitric oxide and virus infection
Authors: Akaike T. , Maeda H. 
Published: March 2003

SummaryNitric oxide (NO) has complex and diverse functions in physiological and pathophysiological phenomena. The mechanisms of many events induced by NO are now well defined, so that a fundamental understanding of NO biology is almost established. Accumulated evidence suggests that NO and oxygen radicals such as superoxide are key molecules in the pathogenesis of various infectious diseases. NO biosynthesis, particularly through expression of an inducible NO synthase (iNOS), occurs in a variety of microbial infections. Although antimicrobial activity of NO is appreciated for bacteria and protozoa, NO has opposing effects in virus infections such as influenza virus pneumonia and certain other neurotropic virus infections. iNOS produces an excessive amount of NO for long periods, which allows generation of a highly reactive nitrogen oxide species, peroxynitrite, via a radical coupling reaction of NO with superoxide. Thus, peroxynitrite causes oxidative tissue injury through potent oxidation and nitration reactions of various biomolecules. NO also appears to affect a host's immune response, with immunopathological consequences. For example, overproduction of NO in virus infections in mice is reported to suppress type 1 helper T‐cell‐dependent immune responses, leading to type 2 helper T‐cell‐biased immunological host responses. Thus, NO may be a host response modulator rather than a simple antiviral agent. The unique biological properties of NO are further illustrated by our recent data suggesting that viral mutation and evolution may be accelerated by NO‐induced oxidative stress. Here, we discuss these multiple roles of NO in pathogenesis of virus infections as related to both non‐specific inflammatory responses and immunological host reactions modulated by NO during infections in vivo.
Two independent pathways of maternal cell transmission to offspring: through placenta during pregnancy and by breast‐feeding after birth
Authors: Zhou L. , Yoshimura Y. , Huang Y.‐Y. , Suzuki R. , Yokoyama M. , Okabe M. , Shimamura M. 
Published: March 2003

SummaryCell transmission from mother to offspring was demonstrated using mice with green fluorescent protein (GFP) transgenic markers. GFP transgene heterozygous (+/−) females were mated with GFP (−/−) males, and GFP+ cells in the GFP (−/−) fetuses generated between them were analysed to assess maternal blood cell transmission to conceptuses in utero. The GFP+ maternal cells were observed throughout the body of the fetuses, as shown by fluorescence stereomicroscopy. Cell entrance into the fetal immune system was shown by histochemical and flow cytometric analyses of fetal organs such as thymus, spleen and liver. The GFP+ maternal cells persisted in the offspring until postpartum. Next, GFP (−/−) neonates fed by GFP+ foster mothers were examined to study the transfer of maternal milk leucocytes to offspring through breast‐feeding. GFP+ leucocytes that had infiltrated through the wall of the digestive tract were mainly localized in the livers of neonates. Their accumulation in the livers reached a maximum on days 5 or 6, and these cells became undetectable, as assessed by either histochemistry or flow cytometry, after day 9 of starting foster nursing. Collectively, the present results demonstrate two independent pathways of maternal cell transmission to offspring: transplacental passage during pregnancy and breast‐feeding after birth.
Studies of delayed systemic effects of ultraviolet B radiation (UVR) on the induction of contact hypersensitivity, 2. Evidence that interleukin‐10 from UVR‐treated epidermis is the critical mediator
Authors: Kurimoto I. , Kitazawa T. , Streilein J. W. 
Published: March 2003

SummaryAcute, low‐dose ultraviolet B radiation (UVR) alters cutaneous immunity at the local site as well as systemically. Within 2–3 days of UVR exposure, recipient mice lose their capacity to develop contact hypersensitivity (CH) when hapten is painted on unexposed skin. This loss correlates temporally with a functional deficit among dendritic antigen‐presenting cells within non‐draining lymph nodes and spleen. In the experiments described, the delayed systemic immune deficiency following acute, low‐dose UVR exposure was found to be eliminated with neutralizing anti‐interleukin‐10 (IL‐10) antibody. Intracutaneous injection of IL‐10 generated a deficiency of systemic immunity as well as a functional deficit among lymph node dendritic cells that was similar to that induced by UVR. The skin itself was found to be the source of the IL‐10 responsible for these defects, and epidermis (presumably keratinocytes) rather than mast cells was found to be the source of IL‐10 within UVR‐exposed skin. The potential relationships are discussed between the delayed systemic immune deficit created by acute, low‐dose UVR, and the systemic immune deficits caused by chronic, high‐dose UVR and by a single, high‐dose UVR exposure.
Human amniotic fluid lacks interleukin‐2 and interleukin‐15 but can interact with the β‐chain of the interleukin‐2 receptor
Authors: Searle R. F. , Bromage S. J. , Palmer J. , Curry J. E. , Lang A. K. 
Published: March 2003

SummaryThe present study investigated whether an explanation for the conflicting reports on the interleukin‐2 (IL‐2) status of amniotic fluid is due to the presence of IL‐15 which shares biological activities with IL‐2 and utilizes the IL‐2 receptor β‐chain. Amniotic fluids from 45 normally progressing pregnancies between 14 and 16 weeks after the last menstrual period were assayed for IL‐2 and IL‐15 by bioassay and enzyme‐linked immunosorbent assay (ELISA). The ability of amniotic fluids to induce cytotoxic T lymphoblastoid line‐2 (CTLL‐2) cell proliferation was demonstrated to be dependent upon bioassay culture conditions. In serum‐free medium each amniotic fluid stimulated CTLL‐2 proliferation with a mean level of IL‐2‐like bioactivity of 14·7 ± 2·3 ng/ml but amniotic fluids failed to induce CTLL‐2 proliferation in serum‐supplemented medium. Treatment with neutralizing anti‐IL‐2 or anti‐IL‐15 antibodies failed to inhibit amniotic fluid‐induced CTLL cell proliferation in serum‐free medium, indicating a lack of IL‐2 and IL‐15 bioactivity. In contrast, treatment with anti‐IL‐2 receptor β‐chain antibody significantly reduced amniotic fluid‐induced proliferation. The lack of IL‐2 and IL‐15 activity in amniotic fluids was confirmed using ELISA. Although high levels of IL‐15 immunoactivity were detected in all samples, specificity controls showed a lack of specific IL‐15 immunoactivity in amniotic fluid. Pretreatment of amniotic fluids with 100–500 ng/ml mouse immunoglobulin G abrogated IL‐15 immunoactivity, indicating that amniotic fluid contains molecules binding to Fc regions of immunoglobulins and responsible for false ELISA positivity. These studies unequivocally show that amniotic fluid lacks IL‐2 and IL‐15 but can stimulate CTLL‐2 cell proliferation via the IL‐2 receptor β‐chain. The absence of IL‐2 and IL‐15 in normal mid‐trimester amniotic fluid suggests that the cytokine profile of human pregnancy appears to be associated with a bias against type 1 cytokines within the feto–placental unit.
The identification of plant lectins with mucosal adjuvant activity
Authors: Lavelle E. C. , Grant G. , Pusztai A. , Pfüller U. , O'hagan D. T. 
Published: March 2003

SummaryTo date, the most potent mucosal vaccine adjuvants to be identified have been bacterial toxins. The present data demonstrate that the type 2 ribosome‐inactivating protein (type 2 RIP), mistletoe lectin I (ML‐I) is a strong mucosal adjuvant of plant origin. A number of plant lectins were investigated as intranasal (i.n.) coadjuvants for a bystander protein, ovalbumin (OVA). As a positive control, a potent mucosal adjuvant, cholera toxin (CT), was used. Co‐administration of ML‐I or CT with OVA stimulated high titres of OVA‐specific serum immunoglobulin G (IgG) in addition to OVA‐specific IgA in mucosal secretions. CT and ML‐I were also strongly immunogenic, inducing high titres of specific serum IgG and specific IgA at mucosal sites. None of the other plant lectins investigated significantly boosted the response to co‐administered OVA. Immunization with phytohaemagglutinin (PHA) plus OVA elicited a lectin‐specific response but did not stimulate an enhanced response to OVA compared with the antigen alone. Intranasal delivery of tomato lectin (LEA) elicited a strong lectin‐specific systemic and mucosal antibody response but only weakly potentiated the response to co‐delivered OVA. In contrast, administration of wheatgerm agglutinin (WGA) or Ulex europaeus lectin 1 (UEA‐I) with OVA stimulated a serum IgG response to OVA while the lectin‐specific responses (particularly for WGA) were relatively low. Thus, there was not a direct correlation between immunogenicity and adjuvanticity although the strongest adjuvants (CT, ML‐I) were also highly immunogenic.
Interleukin (IL)‐18 induces Langerhans cell migration by a tumour necrosis factor‐α‐ and IL‐1β‐dependent mechanism
Authors: Cumberbatch M. , Dearman R. J. , Antonopoulos C. , Groves R. W. , Kimber I. 
Published: March 2003

SummaryFollowing skin sensitization a proportion of epidermal Langerhans cells (LC) are stimulated to leave the skin and to migrate, via afferent lymphatics, to draining lymph nodes where they accumulate as immunostimulatory dendritic cells (DC). It has been demonstrated previously that tumour necrosis factor‐α (TNF‐α), an inducible product of epidermal keratinocytes, and interleukin (IL)‐1β, produced exclusively by LC in murine epidermis, provide important signals for the initiation of this response. Recently, it has been demonstrated that IL‐18, a cytokine produced by both LC and keratinocytes within the epidermis, may also participate in immune responses induced following skin sensitization. In the present investigations, the ability of IL‐18 to contribute to the regulation of LC migration and the accumulation of DC in draining lymph nodes has been examined. It was found that, like IL‐1β, IL‐18 administered intradermally to mice resulted in a significant reduction in epidermal major histocompatibility complex (MHC) class II+ LC densities and a marked increase in lymph node DC numbers. Using neutralizing anti‐TNF‐α and blocking anti‐type I IL‐1 receptor (IL‐1RI) antibodies, it was shown also that the induction by IL‐18 of both LC mobilization and DC accumulation in regional lymph nodes was dependent upon availability of TNF‐α and the integrity of IL‐1RI signalling. Furthermore, using IL‐1β converting enzyme (caspase‐1) knockout mice, IL‐18‐induced LC migration was found to have a mandatory requirement for active IL‐1β. Importantly, not only was IL‐18 able to contribute to the regulation of LC migration, it was found to be essential for the manifestation of these processes in response to topical sensitization with the contact allergen oxazolone.
The 3′‐untranslated region of human interleukin‐8 mRNA suppresses IL‐8 gene expression
Authors: Yu Y. , Chadee K. 
Published: March 2003

SummaryAlthough adenosine/uridine (AU)‐rich sequences in the 3′‐untranslated region (UTR) of the interleukin‐8 (IL‐8) gene have been suggested to contribute to its post‐transcriptional regulation, the molecular basis whereby this occurs still needs to be understood. To investigate the role of the 3′‐UTR on human IL‐8 gene regulation, chimeric reporter genes were generated by adding full length or differentially deleted 3′‐UTR of the IL‐8 gene to chloramphenicol acetyltransferase (CAT). Addition of the entire IL‐8 3′‐UTR markedly reduced CAT mRNA and protein expression in COS 7 cells. In a reporter gene study, IL‐8 3′‐UTR destabilized CAT mRNA, which was dependent on active transcription in COS 7 cells. A 357‐base sequence (nucleotides (nt) 2387–2743 of genomic DNA) within 3′‐UTR, designated e, suppressed CAT gene expression by accelerating CAT mRNA turnover. A 26‐base AU‐rich sequence (nt 2552–2577) within e, containing four AUUUA pentamers that form two UAUUUAUU and one UUAUUUAU octamers, did not suppress CAT gene expression. However, deletion of the AU‐rich sequences attenuated the inhibitory effect of e on CAT gene expression. Elimination of the first 100 bases (nt 2386–2486) attenuated the potency of fragment e, but much weaker than elimination of the first 146 bases (nt 2387–2533). This study gives new insights in unravelling the molecular mechanisms involved in the post‐transcriptional regulation of the IL‐8 gene.
CD8+ T cells in human uterine endometrial lymphoid aggregates: evidence for accumulation of cells by trafficking
Authors: Yeaman G. R. , Collins J. E. , Fanger M. W. , Wira C. R. 
Published: March 2003

SummaryLymphoid aggregates (LA) develop during the proliferative phase of the menstrual cycle in the human uterine endometrium (EM). They contain mostly CD8+ T cells and B cells. As these LA are absent immediately following menses, they may arise by division of cells resident in the EM, or by division of a limited number of precursor cells that traffic into the EM during the early proliferative phase of the menstrual cycle. Alternatively, they may arise by the continuous trafficking of cells into the EM throughout the proliferative phase of the menstrual cycle. In this study we investigated the distribution and frequency of CD8+ T cells in the aggregates using expression of Vβ2 or Vβ8 as markers of clonality and Ki‐67 as a marker of dividing cells. Confocal microscopic analysis of endometrial tissues showed the random distribution of CD8+ T cells within aggregates within the same sample and in aggregates from different samples. Furthermore, comparisons of the distribution of Vβ2 and Vb8 with expected values predicted from Poisson distribution values were not significantly different, suggesting that CD8+ T cells do not arise by division from single precursors. A low level of T‐cell division within LAs was confirmed by positive staining for Ki‐67. Dividing T cells were randomly dispersed throughout the LA and the frequency of dividing cells did not vary greatly between aggregates within the same tissue. Nearest‐neighbour analysis of dividing cells showed no statistically significant deviations from a random distribution. Taken together, these results suggest that LA develop during the menstrual cycle largely by the trafficking of cells to nucleation sites within the EM, rather than by division of a limited number of precursor cells.
Mycobacterium avium infection in CD14‐deficient mice fails to substantiate a significant role for CD14 in antimycobacterial protection or granulomatous inflammation
Authors: Ehlers Stefan , Reiling Norbert , Gangloff Sophie , Woltmann Alexander , Goyert Sanna 
Published: March 2003

SummaryCD14 is a pattern‐recognition receptor implicated in the inflammatory response to microbial components such as lipopolysaccharide, peptidoglycan and lipoarabinomannan. In this work, we made use of CD14‐deficient (CD14−/−) mice to evaluate the relative importance of CD14 in response to infection with viable, intact cells of Mycobacterium avium in vitro and in vivo. Following co‐incubation of either bone marrow‐derived macrophages (Mφ) or thioglycollate‐elicited peritoneal Mφ from CD14−/− mice with viable M. avium, tumour necrosis factor (TNF) production was significantly reduced and delayed compared to TNF secretion by infected CD14+/+ Mφ. However, following intravenous infection with a M. avium strain of either high virulence (TMC724) or intermediate virulence (SE01), there was no difference in the bacterial loads of lungs, livers or spleens at 3, 5 and 8 weeks postinfection in CD14−/− mice when compared with syngeneic CD14+/+ mice. At these time‐points, TNF and interferon‐γ (IFN‐γ) mRNA expression in the liver was similar in infected CD14+/+ and CD14−/− mice, and granuloma formation and expression of inducible nitric oxide synthase within granuloma Mφ was the same in both mouse groups. In conclusion, although the absence of CD14 results in significantly reduced and delayed TNF production in response to stimulation with M. avium in vitro, there is no evidence that CD14 plays a significant role in either the antibacterial defence or the chronic granulomatous reaction to M. avium infection in vivo.
Streptococcal inhibitor of complement (SIC) inhibits the membrane attack complex by preventing uptake of C567 onto cell membranes
Authors: Fernie‐King Barbara A. , Seilly David J. , Willers Christine , Würzner Reinhard , Davies Alexandra , Lachmann Peter J. 
Published: March 2003

SummaryStreptococcal inhibitor of complement (SIC) was first described in 1996 as a putative inhibitor of the membrane attack complex of complement (MAC). SIC is a 31 000 MW protein secreted in large quantities by the virulent Streptococcus pyogenes strains M1 and M57, and is encoded by a gene which is extremely variable. In order to study further the interactions of SIC with the MAC, we have made a recombinant form of SIC (rSIC) in Escherichia coli and purified native M1 SIC which was used to raise a polyclonal antibody. SIC prevented reactive lysis of guinea pig erythrocytes by the MAC at a stage prior to C5b67 complexes binding to cell membranes, presumably by blocking the transiently expressed membrane insertion site on C7. The ability of SIC and clusterin (another putative fluid phase complement inhibitor) to inhibit complement lysis was compared, and found to be equally efficient. In parallel, by enzyme‐linked immunosorbent assay both SIC and rSIC bound strongly to C5b67 and C5b678 complexes and to a lesser extent C5b‐9, but only weakly to individual complement components. The implications of these data for virulence of SIC‐positive streptococci are discussed, in light of the fact that Gram‐positive organisms are already protected against complement lysis by the presence of their peptidoglycan cell walls. We speculate that MAC inhibition may not be the sole function of SIC.
The role of prostaglandin E2 in the immunopathogenesis of experimental pulmonary tuberculosis
Authors: Rangel Moreno Javier , Estrada García Iris , De La Luz García Hernández María , Aguilar Leon Diana , Marquez Ricardo , Hernández Pando Rogelio 
Published: March 2003

SummaryProstaglandins (PG) are potent mediators of intercellular communication, and PGE2 at high concentration is immunosuppressive for T‐cell‐mediated immunity. We studied the kinetics of PGE2 production and the expression of the enzymes related to its synthesis during the course of experimental pulmonary tuberculosis. Secondly, we analysed the pathological and immunological changes produced by the pharmacological suppression of PG production. In BALB/c mice infected via the trachea with Mycobacterium tuberculosis H37Rv there is an initial phase of partial resistance, dominated by type 1 cytokines plus tumour necrosis factor‐α (TNF‐α) and expression of the inducible form of nitric oxide synthase (iNOS), followed by a phase of progressive disease. During the early phase of the infection some activated macrophages located in the alveolar‐capillary interstitium and in granulomas showed strong PGE2 immunostaining. However, PGE2 concentrations were relatively low and stable. Animals in this early phase of infection were treated with niflumic acid, a potent and specific blocker of cyclo‐oxygenase 2, the rate‐limiting enzyme of PG production. In comparison with control animals, the suppression of PG synthesis produced higher inflammation and expression of TNF‐α, interleukin‐1α and interferon‐γ (IFN‐γ), but almost complete disappearance of iNOS expression, which coexisted with a significant increment of bacterial load. The late progressive phase in this experimental model is characterized by progressive pneumonia, small granulomas and diminished expression of IFN‐γ, TNF‐α and iNOS in coexistence with high expression of IL‐4. Strong PGE2 immunostaining was seen in foamy macrophages localized in the pneumonic areas, and the PGE2 concentration was four‐fold higher in this late phase of infection than during the early phase. When PG production was suppressed in animals suffering advanced phase infection, a significant reduction of pneumonia and bacillus load with striking increment of granuloma size was seen, and the expression of IFN‐γ, TNF‐α and iNOS was also improved. These findings demonstrate a significant participation of PGE2 in the pathogenesis of pulmonary tuberculosis, showing that during the early phase of the infection there are low PGE2 concentrations which contribute to iNOS expression permitting the temporal control of bacillus growth, while the high PGE2 concentrations during the late phase of the disease contribute to down‐regulate cell‐mediated immunity, permitting disease progression.
Conjunctival macrophage‐mediated influence of the local and systemic immune response after corneal herpes simplex virus‐1 infection
Authors: Bauer Dirk , Schmitz Andreas , Van Rooijen Nico , Steuhl Klaus‐Peter , Heiligenhaus Arnd 
Published: March 2003

SummaryRecently it has been shown that selective subconjunctival macrophage depletion reduced the incidence and severity of stromal herpes simplex virus (HSV) keratitis in mice. In this study, we examined the effect of conjunctival macrophage depletion on the corneal and systemic T‐cell‐mediated immune response. BALB/c mice were treated with subconjunctival injections of dichloromethylene diphosphonate (Cl2MDP)‐liposomes (Cl2MDP‐LIP) or phosphate‐buffered saline (PBS) 7 and 2 days before corneal infection with 105 plaque‐forming units (PFU) of HSV‐1 (KOS strain). Interferon (IFN)‐γ, interleukin (IL)‐2, and IL‐4 production in the cornea was analysed by enzyme‐linked immunosorbent assay (ELISA), and cytokine mRNA levels (IFN‐γ, IL‐4) were measured by semiquantitative reverse transcription–polymerase chain reaction (RT‐PCR). Cell culture supernatants from submandibular lymph nodes were analysed by ELISA for expression of IFN‐γ, IL‐2, and IL‐4 and by bioassay for IL‐6. The HSV‐1‐specific proliferative response of lymphocytes from regional lymph nodes and the delayed‐type hypersensitivity (DTH) response were tested after corneal infection. Virus‐neutralizing antibody titres and HSV‐1‐specific immunoglobulin G (IgG)2a/IgG1‐ratios were measured. Cytokine mRNA expression (IFN‐γ, IL‐4) and secretion (IFN‐γ, IL‐2, IL‐4) in the corneas were decreased after HSV‐1 corneal infection in the macrophage‐depleted mice. The secretion of IFN‐γ and IL‐2 was decreased in the regional lymph nodes from Cl2MDP‐LIP‐treated animals (P<0·05). Furthermore, Cl2MDP‐LIP‐treated mice had decreased HSV‐1 specific proliferative responses (P<0·05) and DTH response after corneal HSV‐1 infection (P<0·05). The virus‐neutralizing serum‐antibody levels (P<0·05) increased while the HSV‐1 specific IgG2a/IgG1‐ratio was unaffected after macrophage depletion. Macrophage depletion did not induce a shift between the T helper 1 (Th1) and Th2 response in this HSK model. The data suggest that conjunctival macrophage functions are enhancing the T‐cell‐mediated immune response after corneal infection. This effect is at least in part responsible for the impaired course of herpetic keratitis after macrophage depletion.