Functional relevance of NLRP3 inflammasome-mediated interleukin (IL)-1ß during acute allergic airway inflammation.

Overall asthmatic symptoms can be controlled with diverse therapeutic agents. However, certain symptomatic individuals remain at risk for serious morbidity and mortality, which prompts the identification of novel therapeutic targets and treatment strategies. Thus, using an adjuvant-free T helper type 2 (Th2) murine model, we have deciphered the role of interleukin (IL)-1 signalling during allergic airway inflammation (AAI). Because functional IL-1ß depends on inflammasome activation we first studied asthmatic manifestations in specific inflammasome-deficient [NACHT, LRR and PYD domains-containing protein 3 (NLRP3(-/-) ) and apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC(-/-) )] and IL-1 receptor type 1(-/-) (IL-1R1(-/-) ) mice on the BALB/c background. To verify the onset of disease we assessed cellular infiltration in the bronchial regions, lung pathology, airway hyperresponsiveness and ovalbumin (OVA)-specific immune responses. In the absence of NLRP3 inflammasome-mediated IL-1ß release all symptoms of AAI were reduced, except OVA-specific immunoglobulin levels. To address whether manipulating IL-1 signalling reduced asthmatic development, we administered the IL-1R antagonist anakinra (Kineret®) during critical immunological time-points: sensitization or challenge. Amelioration of asthmatic symptoms was only observed when anakinra was administered during OVA challenge. Our findings indicate that blocking IL-1 signalling could be a potential complementary therapy for allergic airway inflammation.

Using static and dynamic canonical correlation coefficients as quantitative EEG markers for Alzheimer's disease severity.

We analyzed the relation between Alzheimer's disease (AD) severity as measured by Mini-Mental State Examination (MMSE) scores and quantitative electroencephalographic (qEEG) markers that were derived from canonical correlation analysis. This allowed an investigation of EEG synchrony between groups of EEG channels. In this study, we applied the data from 79 participants in the multi-centric cohort study PRODEM-Austria with probable AD. Following a homogeneous protocol, the EEG was recorded both in resting state and during a cognitive task. A quadratic regression model was used to describe the relation between MMSE and the qEEG synchrony markers. This relation was most significant in the δ and θ frequency bands in resting state, and between left-hemispheric central, temporal and parietal channel groups during the cognitive task. Here, the MMSE explained up to 40% of the qEEG marker's variation. QEEG markers showed an ambiguous trend, i.e. an increase of EEG synchrony in the initial stage of AD (MMSE>20) and a decrease in later stages. This effect could be caused by compensatory brain mechanisms. We conclude that the proposed qEEG markers are closely related to AD severity. Despite the ambiguous trend and the resulting diagnostic ambiguity, the qEEG markers could provide aid in the diagnostics of early-stage AD.

Farm-derived Gram-positive bacterium Staphylococcus sciuri W620 prevents asthma phenotype in HDM- and OVA-exposed mice.

BACKGROUND: Farm-derived dust samples have been screened for bacteria with potential allergo-protective properties. Among those was Staphylococcus sciuri W620 (S. sciuri W620), which we tested with regard to its protective capacities in murine models of allergic airway inflammation. METHODS: We employed two protocols of acute airway inflammation in mice administering either ovalbumin (OVA) or house dust mite extract (HDM) for sensitization. Mechanistic studies on the activation of innate immune responses to S. sciuri W620 were carried out using human primary monocytic dendritic cells (moDC) and co-culture with autologous T cells. RESULTS: The allergo-protective properties of S. sciuri W620 were proven in a T(H)2-driven OVA model as well as in a mixed T(H)1/T(H)2 phenotype HDM model as demonstrated by abrogation of eosinophils and neutrophils in the airways after intranasal treatment. In the HDM model, lymph node cell T(H)1/T(H)2 signature cytokines were decreased in parallel. Studies on human moDC revealed an activation of TLR2 and NOD2 receptors and initiation of DC maturation following incubation with S. sciuri W620. Cytokine expression analyses after exposure to S. sciuri W620 showed a lack of IL-12 production in moDC due to missing transcription of the IL-12p35 mRNA. However, such DC selectively supported T(H)1 cytokine release by co-cultured T cells. CONCLUSION AND CLINICAL RELEVANCE: Our proof-of-concept experiments verify the screening system of farm-derived dust samples as suitable to elucidate new candidates for allergo-protection. S. sciuri W620 was shown to possess preventive properties on airway inflammation providing the basis for further mechanistic studies and potential clinical implication.

Neonatal supplementation of processed supernatant from Lactobacillus rhamnosus GG improves allergic airway inflammation in mice later in life.

BACKGROUND: Oral supplementation with probiotic bacteria can protect against the development of allergic and inflammatory diseases. OBJECTIVE: The aim of this study was to investigate potential immunomodulatory and allergy-protective effects of processed Lactobacillus rhamnosus GG (LGG)-derived supernatants early in life in neonatal mice. METHODS: In vitro, RAW264.7 mouse macrophages were stimulated with viable LGG, LGG-derived supernatants, prepared from different growth phases, and different size fractions thereof, and pro- and anti-inflammatory cytokine production was analysed. Supernatant fractions were also treated with protease, DNAse or carbohydrate-digesting enzymes to define the nature of immunomodulatory components. In vivo, neonatal Balb/c mice were orally supplemented with differentially processed LGG supernatants. Starting at 4 weeks of age, a protocol of ovalbumin-induced acute allergic airway inflammation was applied and protective effects of processed LGG supernatants were assessed. RESULTS: Incubation of RAW264.7 cells with LGG-derived supernatants significantly increased TNFα and IL-10 production. These effects were not restricted to a particular molecular size fraction. Treatment with protease, but not with DNAse or carbohydrate-digesting enzymes, completely abolished the immunomodulatory activities. Incubation of TLR/NOD-transfected cells with LGG-derived supernatants revealed that recognition and signalling of bioactive components is mediated by TLR2 and NOD2. In vivo supplementation of newborn mice with processed LGG-derived supernatants resulted in pronounced protective effects on the allergic inflammatory response as reflected by reduced eosinophil numbers, modified T helper cell cytokine production, significantly less lung inflammation and reduced goblet cell numbers in comparison with sham-treated controls. CONCLUSION: LGG-derived supernatants exert immunomodulatory activities, and neonatal administration of specifically processed supernatants may provide an alternative to viable probiotics in reducing allergic inflammatory responses.

Allergic diseases, gene-environment interactions.

Allergic asthma develops in part from dysregulation of the innate and adaptive immune functions, particularly an imbalance in the Th2-driven adaptive immune response. This dysregulation is the result of complex interactions between genes and environment. These interactions occur both pre- and postnatally, providing opportunities for early interventions in immunological programming.

Development of multiple W/O/W emulsions as dermal carrier system for oligonucleotides: effect of additives on emulsion stability.

Multiple water-in-oil-in-water (W/O/W) emulsions are of major interest as potential skin delivery systems for water-soluble drugs like oligonucleotides due to their distinct encapsulation properties. However, multiple emulsions are highly sensitive in terms of variations of the individual components. The presence of osmotic active ingredients in the inner water phase is crucial for the generation of stable multiple emulsions. In order to stabilize the emulsions the influence of NaCl, MgSO(4), glucose and glycine and two cellulose derivatives was investigated. Briefly, multiple W/O/W emulsions using Span 80 as a lipophilic emulsifier and different hydrophilic emulsifiers (PEG-40/50 stearate, steareth-20 and polysorbate 80) were prepared. Stability of the emulsions was analyzed over a period of time using rheological measurements, droplet size observations and conductivity analysis. In this study we show that additives strongly influence the properties stability of multiple emulsions. By increasing the concentration of the osmotic active ingredients, smaller multiple droplets are formed and the viscosity is significantly increased. The thickening agents resulted in a slightly improved stability. The most promising emulsions were chosen and further evaluated for their suitability and compatibility to incorporate a DNAzyme oligonucleotide as active pharmaceutical ingredient.

Comparison of adjuvant and adjuvant-free murine experimental asthma models.

INTRODUCTION: The most widely used protocol for the induction of experimental allergic airway inflammation in mice involves sensitization by intraperitoneal (i.p.) injections of the antigen ovalbumin (OVA) used in conjunction with the adjuvant aluminium hydroxide (alum). Although adjuvants are frequently used, there are questions regarding the necessity of alum for murine asthma studies due to the non-physiological nature of this chemical. OBJECTIVE: The objective of this study was to compare experimental asthma phenotypes between adjuvant and adjuvant-free protocols of murine allergic airway inflammation in an attempt to develop a standardized alternative to adjuvant use. METHOD: An adjuvant-free OVA model of experimental asthma was investigated in BALB/c mice using i.p. or subcutaneous (s.c.) sensitization routes. For the s.c. sensitization, beta-galactosidase (beta-gal) was also tested as an antigen. In addition, OVA adjuvant and adjuvant-free sensitization protocols were compared in BALB/c and C57BL/6 mice. Open-field testing was performed to assess the effect of alum on mouse behaviour. RESULTS: Comparison of adjuvant vs. adjuvant-free and i.p. vs. s.c. protocols revealed that both adjuvant use and route of antigen application significantly influenced OVA-specific antibody production. Comparison of adjuvant and adjuvant-free protocols in this study clearly demonstrated the non-requirement of alum for the induction of acute allergic airway inflammation, as both protocols induce a similar disease phenotype. BALB/c mice were significantly more susceptible than C57BL/6 mice to sensitization. Using the improved s.c. adjuvant-free protocol, it was demonstrated that alternative antigens such as beta-gal can also be utilized. Behavioural studies indicated severe distress in mice treated with alum. CONCLUSION: The OVA s.c. adjuvant-free protocol used in this study generates a phenotype comparable to the benchmark adjuvant protocol widely used in the literature. The adjuvant-free alternative avoids the added complication of non-physiological adjuvants that may interfere with asthma treatment or prevention strategies.

Composition of the immunoglobulin classic antigen-binding site regulates allergic airway inflammation in a murine model of experimental asthma.

BACKGROUND: When bound to mast cell FcepsilonRI, IgE serves as antigen receptor for allergic reactions, permitting specific identification of the allergen. Although the core of the classic antigen-binding site is heavy chain complementarity determining region 3 (CDR-H3), recent studies suggest that allergens might also bind IgE in a superantigen-like fashion outside the classic antigen-binding site. OBJECTIVE: We sought to evaluate the contribution of the classic CDR-H3-centric antigen-binding site to the development of an allergic phenotype. METHODS: Using a murine model of experimental asthma, we characterized a gene-targeted mouse strain expressing an altered range of CDR-H3s (DeltaD-iD mice) in response to the hydrophobic allergen ovalbumin (OVA). Mutant and wild-type (wt) mice were sensitized intraperitoneally with OVA; non-sensitized mice served as controls. RESULTS: We found the composition of the classic CDR-H3-centric antigen-binding site to be critical for the development of characteristic aspects of allergic asthma. (i) Compared with wt animals, DeltaD-iD mice showed a significantly less pronounced OVA-induced rise in allergen-specific IgE levels and hence in total serum IgE levels. (ii) In addition, DeltaD-iD mice demonstrated a significant reduction in eosinophilic airway inflammation, as well as in interleukin-4 (IL-4), IL-5 and IL-13 levels in BAL fluids. CONCLUSION: Allergic sensitization and airway inflammation depend on the composition of the predominant CDR-H3 repertoire, suggesting that the classic CDR-H3-centric antigen-binding site plays a crucial role in creating the immunological interface between allergen and IgE. Our results further emphasize a central role of IgE, not only in mediating but also in regulating the allergic immune response.

Safety and immunogenicity of a cluster specific immunotherapy in children with bronchial asthma and mite allergy.

BACKGROUND: Cluster specific immunotherapy (SIT) is a modern form of allergen immunotherapy allowing safe administration of high allergen doses in a short time interval compared to classic SIT. In the current study, we investigated the safety profile and immunological effect of cluster SIT in children with allergic asthma due to house dust mite allergy. METHODS: A total of 34 children (6-18 years) with allergic asthma were assigned to cluster (n = 22) or classic SIT (n = 12). To achieve a maintenance dose of allergen extract, cluster patients received 14 injections of house dust mite allergen within 6 weeks, whereas the classic SIT group received 14 injections within 14 weeks. Safety was monitored by recording adverse events. Immunogenicity was measured by specific IgG(Mite) and IgG4(Mite), by antibody-blocking properties on basophil activation, and by the T cell subset transcription factors Foxp3, T-bet, and GATA-3. RESULTS: There were no significant differences in local and systemic side effects between the two groups. In the cluster group, serum levels of specific IgG(Mite) (p < 0.001) and specific IgG4(Mite) (p < 0.001) significantly increased after 8 weeks, while it took 12 weeks in the classic SIT group. These data were confirmed by blocking CD63 expression as well as release of cysteinyl leukotrienes after in vitro basophil stimulation. No differences in transcription factor expression were found in the two groups. CONCLUSION: Cluster SIT is safe in children. Additionally, our data demonstrated an even more rapid induction of specific immune tolerance. Cluster SIT is an attractive alternative to conventional up-dosing schedules with fewer consultations for the patients.

The potential of a protease activation mutant of a highly pathogenic avian influenza virus for a pandemic live vaccine.

The most effective countermeasure against a pandemic originating from a highly pathogenic avian influenza virus (HPAIV) is immunoprophylaxis of the human population. We present here a new approach for the development of a pandemic HPAIV live vaccine. Using reverse genetics, we replaced the polybasic hemagglutinin cleavage site of an H7N7 HPAIV with an elastase motif. This mutant was strictly elastase-dependent, grew equally well as the wild-type in cell culture and was attenuated in mice unlike the lethal wild-type. Immunization at 10(6)pfu dosage protected mice against disease and induced sterile immunity; vaccination with homosubtypic or heterosubtypic reassortants led to cross-protection. These observations demonstrate that a mutated hemagglutinin requiring elastase cleavage can serve as an attenuating component of a live vaccine against HPAIV.

CD4+ T cells from mice with intestinal immediate-type hypersensitivity induce airway hyperreactivity.

BACKGROUND: A subset of food-allergic patients does not only respond clinically with symptoms in the gastro-intestinal tract but also with asthmatic reactions. OBJECTIVE: The aim of this study was to analyse whether CD4+ T cells from mice with intestinal immediate-hypersensitivity reactions to food allergen are involved in the development of experimental asthma. METHODS: BALB/c mice were intraperitoneally sensitized to ovalbumin (OVA), followed by repeated intra-gastric (i.g.) OVA challenges. Control animals were either sham-sensitized or sham-challenged with phosphate-buffered saline (PBS). Duodenum, jejunum, ileum and colon were histologically examined. CD4+ T cells from mesenteric lymph nodes were transferred from various donor groups into recipient mice that received either OVA or PBS aerosol challenges. Recipients were analysed by measurements of lung function using head-out body-plethysmography and examination of broncho-alveolar lavage and lung histology. RESULTS: The highest levels of OVA-specific IgE antibody levels were detected in OVA-sensitized and OVA-challenged mice. Throughout the lower intestinal tract, a marked infiltration with eosinophils was observed, and goblet cell numbers as well as goblet cell area were significantly increased. The villus/crypt ratio was decreased compared with controls. The transfer of CD4+ T cells from mesenteric lymph nodes of OVA-sensitized and OVA-challenged mice triggered airway hyperreactivity and eosinophilic airway inflammation in recipients aerosol challenged with OVA, but not with PBS. CONCLUSION: We conclude that CD4+ T cells from mesenteric lymph nodes of mice with allergen-induced immediate-type hypersensitivity reactions in the gut are able to transfer the phenotype of experimental asthma.

Perinatal maternal application of Lactobacillus rhamnosus GG suppresses allergic airway inflammation in mouse offspring.

BACKGROUND: Clinical studies indicate that maternal exposure to probiotic bacteria may protect from the development of allergic disease later in life. OBJECTIVE: The purpose of this study was to analyse the effects of a perinatal Lactobacillus rhamnosus GG (LGG) supplementation on the development of allergic disorders in offspring. METHODS: Female BALB/c mice received intragastric LGG every other day before conception, during pregnancy and lactation (perinatal supplementation group) or before conception and during pregnancy only (prenatal supplementation group). Cytokine expression of placental tissues was examined. Offspring of LGG-supplemented and sham-exposed mothers were sensitized to Ovalbumin (OVA), followed by aerosol allergen challenges. Development of experimental asthma was assessed by bronchoalveolar lavage analysis, lung histology and lung function measurement. Cytokine production of splenic mononuclear cells was analysed following in vitro stimulation. RESULTS: Intestinal colonization with LGG was observed in mother mice only, but not in the offspring. However, a reduced expression of TNF-alpha, IFN-gamma, IL-5 as well as IL-10 was observed in mice derived from perinatally LGG-supplemented mothers, whereas IL-13 and IL-4 expression remained unchanged. Moreover, in offspring of prenatally or perinatally LGG-supplemented mothers allergic airway and peribronchial inflammation as well as goblet cell hyperplasia were significantly reduced as compared with mice derived from non-supplemented mothers. In contrast, airway hyperresponsiveness to methacholine was not affected. Exposure to LGG during pregnancy only shifted the placental cytokine expression pattern with a markedly increased TNF-alpha level. CONCLUSION: Our data suggest that LGG may exert beneficial effects on the development of experimental allergic asthma, when applied in a very early phase of life. Immunological effects are, at least in parts, mediated via the placenta, probably by induction of pro-inflammatory cell signals.

Involvement of distal airways in a chronic model of experimental asthma.

BACKGROUND: Bronchial asthma is characterized by chronic airway inflammation and airway remodelling which occurs in both proximal and distal airways. These changes are associated with development of airway hyper-responsiveness and airflow limitation. OBJECTIVE: This study was aimed to analyse whether chronic inhalative allergen challenges in mice lead to morphological and physiological changes comparable with this phenotype. METHODS: For this purpose, BALB/c mice were systemically sensitized to ovalbumin (OVA) followed by aerosol allergen challenges on 2 consecutive days per week for 12 weeks. RESULTS: In chronically challenged mice, tissue inflammation in proximal as well as distal airways was observed with a predominance of lymphocytes within the cellular infiltrate. In contrast, inflammation in the airway lumen decreased over time. These changes were associated by a shift in bronchoalveolar lavage-cytokine levels from IL-4, IL-5 and TNF-alpha production (during the acute phase) towards markedly increased levels of TGF-beta during the chronic phase. Goblet cell hyperplasia and subepithelial fibrosis occurred throughout the airway tree. In terms of lung function, chronically challenged mice developed persistent bronchial hyper-responsiveness and progressive airflow limitation. Six weeks after OVA aerosol discontinuation, airway inflammation still persisted although lung function was normalized. CONCLUSION: These data indicate that our model of chronic aerosol allergen challenges leads to a phenotype of experimental asthma with participation of distal airways and persistence of inflammation thereby resembling many morphological and physiological aspects of human bronchial asthma.

A new approach to an influenza live vaccine: modification of the cleavage site of hemagglutinin.

A promising approach to reduce the impact of influenza is the use of an attenuated, live virus as a vaccine. Using reverse genetics, we generated a mutant of strain A/WSN/33 with a modified cleavage site within its hemagglutinin, which depends on proteolytic activation by elastase. Unlike the wild-type, which requires trypsin, this mutant is strictly dependent on elastase. Both viruses grow equally well in cell culture. In contrast to the lethal wild-type virus, the mutant is entirely attenuated in mice. At a dose of 10(5) plaque-forming units, it induced complete protection against lethal challenge. This approach allows the conversion of any epidemic strain into a genetically homologous attenuated virus.

Impaired recycling of surfactant-like liposomes in type II pneumocytes from injured lungs.

BACKGROUND: Surfactant synthesis and secretion has been shown to be impaired in type II cells from diseased lungs. The mechanism of surfactant lipid recycling, which is an important physiological process in surfactant treatment, was studied in type II cells isolated from injured lungs. METHODS: Different stages of lung injury were induced by exposing rats to 10 ppm nitrogen dioxide (NO(2)) for 3, 20, and 28 days. Type II cells were isolated from these lungs and recycling of (3)H-DPPC labelled surfactant-like liposomes was studied in vitro. RESULTS: Uptake of liposomes (150 micro g/ml) for 20 minutes in the absence and presence of surfactant protein-A (SP-A, 5 micro g/ml) was higher in cells from NO(2) injured lungs (63-78%) than in control cells. There was no difference in liposome uptake between the groups with NO(2) exposure of different duration. After liposome uptake, most of the internalised label remained in the phosphatidylcholine (PC) fraction and increased with duration of exposure to NO(2). After 20 minutes internalisation, cells were allowed to resecrete lipids for a further 20 minute period. In cells from controls and from all stages of lung injury, liposomes that had been internalised in the presence of SP-A were resecreted to a greater extent than those internalised without SP-A. However, cells from lungs exposed to NO(2) resecreted less lipid than cells from control lungs. Again, there was no difference in resecretion between the groups with NO(2) exposure of different duration. CONCLUSION: Type II cells from injured lungs internalise more surfactant-like liposomes than cells from controls, suggesting a putative therapeutic significance to cope with limited alveolar surfactant pools in lung injury.

Accumulating monocytes in the vasculature of rat renal allografts: phenotype, cytokine, inducible no synthase, and tissue factor mRNA expression.

BACKGROUND: Necrotic patches and hemorrhagic lesions develop in the renal tissue between day 4 and day 5 after transplantation of fully allogeneic DA rat kidneys to LEW recipients. These lesions are at least in part due to destruction and obstruction of blood vessels. Damage of graft endothelial cells and blood coagulation are likely to be mediated by intravascular graft leukocytes. However, this cell population has not been thoroughly characterized before. METHODS: We perfused untreated control kidneys, renal isografts, and allografts on day 4 after transplantation with phosphate-buffered saline/ethylenediaminetetraacetic acid to harvest leukocytes from both the blood stream as well as from the marginal intravascular pool. The mRNA expression of typical products of activated monocytes was analyzed in reverse-transcriptase polymerase chain reaction experiments. Graft monocytes were purified and their immunophenotype was investigated by flow cytometry. RESULTS: Allograft rejection led to a 10-fold increase in the number of intravascular graft leukocytes compared to isografts. A mean number of about 100x10(6) leukocytes was harvested from a single allogeneic kidney, about 73% of these cells were monocytes and most of them displayed an activated phenotype. Compared to isografts, intravascular allograft leukocytes displayed an increased expression of tumor necrosis factor-alpha, inducible NO synthase and tissue factor. CONCLUSIONS: Our study shows that large numbers of activated monocytes accumulate inside allograft vessels. As they express genes the products of which might damage the allograft by inducing cell death or thrombosis, we speculate that they directly participate in allograft destruction.

Effect of N-acetylcysteine treatment on NO2-impaired type II pneumocyte surfactant metabolism.

Inhalation of nitrogen dioxide (NO2) is known to alter the composition of the bronchoalveolar lavage (BAL) and to impair the surfactant metabolism of type II pneumocytes. However, information is sparse as to whether application of the widely used antioxidant N-acetylcysteine (NAC) is capable of preventing or reducing these alterations. The aim of the study was to investigate if in vivo administration of NAC to NO2-inhaling rats protected BAL parameters and physiology of type II pneumocytes from impairment. For this purpose, rats were exposed to 720 p.p.m. h-1 NO2, that was applied continuously, intermittently or repeatedly. During inhalation one group of rats received saline and the other group received NAC antioxidant (200 mg kg-1, intraperitoneally) once a day. The BAL protein and phospholipid content increased most in the continuously and repeatedly NO2-exposed rats when compared to the controls, while the intermittent exposure did not change these parameters. Application of NAC led to a marked decrease of the protein elevation for the continuously and intermittently exposed groups, but exhibited no influence on the BAL phospholipid. Surprisingly, all NO2 exposure modes elevated the glutathione content (reduced and oxidized) in the BAL. Application of NAC clearly decreased the content of both forms of glutathione in the continuously and the repeatedly NO2-exposed groups. Phospholipid synthesis, measured by choline uptake into type II cells, was increased most after continuous NO2 inhalation. The NAC reduced this increase moderately. Whereas choline uptake by type II cells was obviously stimulated by NO2, the stimulated secretion of phosphatidylcholine from these cells was decreased by this oxidant. Only continuous exposure reduced this activity markedly. The NAC clearly restored the impaired secretion activity in the cells from the continuously NO2-exposed animals. Since the efficacy of NAC in the prevention of NO2-induced impairments in the surfactant system is striking mainly in the continuously exposed group, we suggest that administration of NAC to NO2-induced lung injury partially restores altered BAL components and the impaired physiology of type II pneumocytes.

Experimental silicosis: a shift to a preferential IFN-gamma-based Th1 response in thoracic lymph nodes.

In chronic silicosis, mechanisms leading to lymphocyte activation are still poorly understood, although it is well known that not only the lung but also the draining lymph nodes are affected. In the present study, we investigated T-cell activation by analysis of cytokine expression in the enlarged thoracic lymph nodes of rats 2 mo after an 8-day silica aerosol exposure. In the case of helper T cell (Th) type 1 cytokines, we found a significant increase in interferon (IFN)-gamma mRNA expression, whereas interleukin (IL)-2 expression remained unchanged. In contrast, gene transcription for the Th2-type cytokines IL-4 and IL-10 was diminished. In addition, with use of an in vitro lymphocyte-macrophage coculture system, an enhanced IFN-gamma and a reduced IL-10 release were shown with cells from silicotic animals. With regard to IFN-gamma-inducing cytokines, we observed enhanced IL-12 mRNA levels in vivo, whereas IL-18 gene expression was slightly decreased. These data indicate that a persistent shift toward an IFN-gamma-dominated type 1 (Th1/cytotoxic T cell type 1) T-cell reaction pattern occurred within the thoracic lymph nodes of silicotic animals. Thus a mutual activation of lymphocytes and macrophages may maintain the chronic inflammatory changes that characterize silicosis.

Chemokine expression during acute rejection of rat kidneys.

During acute rejection of fully allogeneic rat renal allografts, few neutrophil granulocytes are detected, whereas an abundant infiltrate of macrophages and T lymphocytes becomes apparent. The mechanisms leading to this specific pattern of infiltration are not understood. We performed a sequential daily Northern blot analysis of the mRNA expression of the CC-chemokines MCP-1, MIP-1alpha and RANTES and of the CXC-chemokines GRO/KC and MIP-2 in rat renal isografts (LEW --> LEW, n = 1 per day) and allografts during acute rejection (DA --> LEW, n = 3 per day). MCP-1 gene expression strongly increased on days 3-4 after allotransplantation and returned to control levels on day 6. The expression of MIP-1alpha and RANTES continuously rose until day 3-4 and remained stable thereafter. Isografts displayed minor changes in CC-chemokine expression. In contrast to CC-chemokines, GRO/KC was expressed in low amounts during rejection and MIP-2 mRNA remained undetectable. In conclusion, the expression of the CC-chemokines MCP-1, MIP-1 and RANTES was clearly upregulated during rejection, whereas the mRNA of the CXC-chemokines MIP-2 and GRO/KC was not detected at all or remained at low levels. This pattern of chemokine gene expression is in good accordance with the predominant mononuclear leukocyte infiltrate in allografts.

Occupational exposure to high frequency electromagnetic fields and its effect on human immune parameters.

The present study recorded a considerable excess of recommended exposure limits in the vicinity of shortwave diathermy devices used for medical treatment of patients. Different kinds of field probes were used to measure electric and magnetic field strength and the whole body exposure of medical personnel operating shortwave, decimeter wave and microwave units was calculated. To investigate the influence of chronic exposure on the immune system of operators, blood was sampled from physiotherapists working at the above mentioned devices. Eighteen exposed and thirteen control persons, matched by sex and age, were examined. Total leucocyte and lymphocyte counts were performed and leucocytic subpopulations determined by flow cytometry and monoclonal antibodies against surface antigens. In addition, to quantify subpopulations of immunocompetent cells, the activity of lymphocytes was measured. Lymphocytes were stimulated by mitogen phytohemagglutinin and their proliferation measured by a flow cytometric method. No statistically significant differences between the control and exposed persons were found. In both study groups all immune parameters were within normal ranges.