Thomas Tschernig

Bronchus-Associated Lymphoid Tissue (BALT) Is Not Present in the Normal Adult Lung but in Different Diseases

Bronchus-associated lymphoid tissue (BALT) was first described in the lungs of rabbits and differs greatly between species. It is part of the integrated mucosal immune system. This review clarifies its morphological definition and focuses on the situation in humans. The frequency of BALT at different ages, after chronic stimulation and in different diseases is described. In healthy humans, BALT can only be found in the lungs of children and adolescents. The role of BALT in lung transplantation and in the development of low-grade malignant lymphomas in the airways is also discussed. Furthermore, questions concerning the inducibility of BALT as an entry site for vaccines, and the regulation of its activity for future therapeutic interventions in pulmonary immune reactions are addressed.

A Codominant Role of FcγRI/III and C5aR in the Reverse Arthus Reaction

Recent attempts to specify the relative contribution of FcR and complement in various experimental systems of immune complex disease have led to opposing conclusions. As concluded in IgG FcRγ−/− mice, manifestation of disease is almost exclusively determined by FcγR on effector cells, arguing for a minor role of complement. In contrast, data obtained with C5aR−/− mice suggested that, dependent on the tissue site, complement is more important than FcγR. In this paper, we demonstrate that, in response to IgG immune complex formation, FcγRI/III- and C5aR-mediated pathways are both necessary and only together are they sufficient to trigger the full expression of inflammation in skin and lung. Moreover, both effector systems are not entirely independent, suggesting an interaction between FcγR and C5aR. Therefore, FcγR-mediated responses can be integrated through C5aR activation, which may explain why these two receptor pathways have previously been considered to dominate each other.

Airway exposure to bacterial superantigen (SEB) induces lymphocyte-dependent airway inflammation associated with increased airway responsiveness – a model for non-allergic asthma

Although immunological consequences of systemic superantigen administration have been extensively studied, the effects of local mucosal exposure to superantigens are not well defined. The purpose of this study was to delineate the type of immune response triggered by superantigen exposure to the airway mucosa in mice. In dose‐response experiments we determined a low dose of staphylococcal enterotoxin B (SEB) that triggered an inflammatory response characterized by mucosal and airway recruitment of lymphocytes, eosinophils and neutrophils together with elevated levels of IL‐4, but not IFN‐γ, in bronchoalveolar lavage (BAL) fluids. TCR Vβ analysis revealed that superantigen‐responsive and ‐non‐responsive T cells were equally recruited into the airways. SEB markedly enhanced the frequency of TNF‐α‐positive BAL macrophages as well as the amount of TNF‐α in BAL fluids. These responses were associated with the development of increased airway responsiveness (AR) in SEB‐treated mice. This effect occurred in an antibody‐independent fashion. Furthermore, this type of response was observed in IgE‐high responder BALB/c as well as in IgE‐low/intermediate responder C57BL/6 mice. The development of increased AR was CD4+ T cell dependent as shown by transfer experiments into BALB/c nu/nu mice. These results suggest that the local immune response following mucosal superantigen administration triggers a unique inflammatory response in the airways resembling many features of “intrinsic asthma”.

Nasal‐associated lymphoid tissue (NALT): frequency and localization in young children

In mucosal immunology nasal‐associated lymphoid tissue (NALT) is taken as a constitutive structure of the nasal immune system and as a target tissue in strategies of local defence and an induction site for vaccination. These concepts are based on findings in rodents, but it has not been investigated systematically whether NALT also is present in humans and if so in which amount and localization. In a postmortem study the presence of NALT in humans is documented as a morphologically distinct structure additional to the lymphoid structures of the Waldeyers ring. Human nasal tissue blocks of 150 children who had died in the first two years of life either of sudden infant death (n = 109) without signs of respiratory tract infections or of different traumatic (n = 22) and natural causes of death (n = 19) were obtained using a specific autopsy‐technique and were investigated systematically using histology. Clearly in contrast to rodents human NALT was found disseminated in the nasal mucosa with typical morphological features in 38% of all children, mainly in the middle concha, with similar morphology and frequency in the examined groups. No correlation was found between the presence of NALT and the cause of death and especially the grade of inflammation in general. Therefore, NALT might be the morphological basis for inhalative vaccination strategies in young children and play a role in mucosal host defence.

Role of Inducible Nitric Oxide Synthase and NADPH Oxidase in Early Control of Burkholderia pseudomallei Infection in Mice

ABSTRACT Infection with the soil bacterium Burkholderia pseudomallei can result in a variety of clinical outcomes, including asymptomatic infection. The initial immune defense mechanisms which might contribute to the various outcomes after environmental contact with B. pseudomallei are largely unknown. We have previously shown that relatively resistant C57BL/6 mice can restrict bacterial B. pseudomallei growth more efficiently within 1 day after infection than highly susceptible BALB/c mice. By using this model, our study aimed to investigate the role of macrophage-mediated effector mechanisms during early B. pseudomallei infection. Depletion of macrophages revealed an essential role of these cells in the early control of infection in BALB/c and C57BL/6 mice. Strikingly, the comparison of the anti-B. pseudomallei activity of bone marrow-derived macrophages (BMM) from C57BL/6 and BALB/c mice revealed an enhanced bactericidal activity of C57BL/6 BMM, particularly after gamma interferon (IFN-γ) stimulation. In vitro experiments with C57BL/6 gp91phox−/− BMM showed an impaired intracellular killing of B. pseudomallei compared to experiments with wild-type cells, although C57BL/6 gp91phox−/− cells still exhibited substantial killing activity. The anti-B. pseudomallei activity of C57BL/6 iNOS−/− BMM was not impaired. C57BL/6 gp91phox−/− mice lacking a functional NADPH oxidase were more susceptible to infection, whereas C57BL/6 mice lacking inducible nitric oxide synthase (iNOS) did not show increased susceptibility but were slightly more resistant during the early phase of infection. Thus, our data suggest that IFN-γ-mediated but iNOS-independent anti-B. pseudomallei mechanisms of macrophages might contribute to the enhanced resistance of C57BL/6 mice compared to that of BALB/c mice in the early phase of infection.

Systemic use of the endolysin Cpl-1 rescues mice with fatal pneumococcal pneumonia.

Objectives:Community-acquired pneumonia is a very common infectious disease associated with significant morbidity and mortality. Streptococcus pneumoniae is the predominant pathogen in this disease, and pneumococcal resistance to multiple antibiotics is increasing. The recently purified bacteriophage endolysin Cpl-1 rapidly and specifically kills pneumococci on contact. The aim of this study was to determine the therapeutic potential of Cpl-1 in a mouse model of severe pneumococcal pneumonia. Design:Controlled, in vivo laboratory study. Subjects:Female C57/Bl6 mice, 8–12 weeks old. Interventions:Mice were transnasally infected with pneumococci and therapeutically treated with Cpl-1 or amoxicillin by intraperitoneal injections starting 24 or 48 hours after infection. Measurements and Main Results:Judged from clinical appearance, decreased body weight, reduced dynamic lung compliance and Pao2/Fio2 ratio, and morphologic changes in the lungs, mice suffered from severe pneumonia at the onset of therapy. When treatment was commenced 24 hours after infection, 100% Cpl-1–treated and 86% amoxicillin-treated mice survived otherwise fatal pneumonia and showed rapid recovery. When treatment was started 48 hours after infection, mice had developed bacteremia, and three of seven (42%) Cpl-1–treated and five of seven (71%) amoxicillin-treated animals survived. Cpl-1 dramatically reduced pulmonary bacterial counts, and prevented bacteremia, systemic hypotension, and lactate increase when treatment commenced at 24 hours. In vivo, treatment with Cpl-1 or amoxicillin effectively reduced counts of penicillin-susceptible pneumococci. The inflammatory response in Cpl-1–and amoxicillin-treated mice was lower than in untreated mice, as determined by multiplex cytokine assay of lung and blood samples. In human epithelial cell cultures, lysed bacteria evoked less proinflammatory cytokine release and cell death, as compared with viable bacteria. Conclusions:Cpl-1 may provide a new therapeutic option in the treatment of pneumococcal pneumonia.

Selective blockade of interleukin-6 trans-signaling improves survival in a murine polymicrobial sepsis model*

Objective: The pleiotropic cytokine interleukin (IL)-6 seems to play a pivotal role in sepsis, but contradictory findings in animal models impede a rationale for therapies directed against IL-6. IL-6 signals by two mechanisms via the ubiquitous transmembrane glycoprotein 130 (gp130): “classic” signaling using membrane-bound IL-6 receptor (IL-6R) and trans-signaling using soluble IL-6R (sIL-6R). Trans-signaling is selectively inhibited by soluble gp130 (sgp130). The aim of this study was to systematically compare complete blockade of IL-6 signaling (using a neutralizing anti-IL-6 antibody) and selective blockade of IL-6 trans-signaling (using a fusion protein of sgp130 and the crystallizable fragment of immunoglobulin G1, sgp130Fc) in a standardized cecal ligation and puncture (CLP) sepsis model. Design: Animal study. Setting: Animal laboratory. Subjects: C57BL/6J mice. Interventions: We performed a 96-hr dose-response study and a 24-hr study to investigate short-term mechanisms. In the 96-hr study, CLP was performed in 120 randomized mice (20 mice received vehicle, 10 mice per dose group). Mice were treated with equimolar doses of sgp130Fc (0.01/0.1/1/10 mg/kg) or anti-IL-6 (0.008/0.08/0.8/8 mg/kg) 24 hrs before CLP. Two additional groups received 0.5 mg/kg sgp130Fc 24 hrs before or 1 mg/kg sgp130Fc 24 hrs after CLP. Survival and activity scores were obtained daily until 96 hrs after CLP. In the 24-hr study, mice were randomized into four groups with 10 animals each (sham/vehicle, CLP/vehicle, CLP/anti-IL-6 [0.8 mg/kg], and CLP/sgp130Fc [1 mg/kg]) and killed after 24 hrs. Measurements and Main Results: In contrast to anti-IL-6, pretreatment with sgp130Fc significantly and dose-dependently increased survival from 45% to 100%. In addition, 1 mg/kg sgp130Fc administered 24 hrs after CLP increased survival from 45% to 80%. Mechanistically, sgp130Fc efficacy was reflected by complete prevention of epithelial cell apoptosis in the jejunum after CLP, which was not achieved with anti-IL-6. Conclusion: Selective inhibition of IL-6 trans-signaling by sgp130Fc has considerable potential for the treatment of sepsis and related disorders.

Cloning and characterization of gp36, a human mucin-type glycoprotein preferentially expressed in vascular endothelium

A mucin-type glycoprotein has been described in murine, rat and canine tissues as a differentiation antigen and influenza-virus receptor. We have cloned a cDNA from human placenta RNA encoding the corresponding human protein, a type-I integral membrane protein of 162 amino acids. Madin-Darby canine kidney cells transfected with the cDNA clone directed the cell-surface expression of a 36-kDa O-glycosylated sialoglycoprotein, gp36, and two minor isoforms of 28 and 70 kDa. gp36 has a broad tissue distribution with strong expression in lung, placenta and skeletal muscle, as shown by PCR screening of different cDNA libraries. Immunohistochemical detection of gp36 in cryo-sections of human placenta, kidney, lung and nasal polyps showed that the glycoprotein is expressed at the apical plasma membrane of vascular endothelial cells. Expression of gp36 was not restricted to endothelial cells, as alveolar epithelial cells were found to express gp36 as well.

Bronchus-associated lymphoid tissue (BALT) in the lungs of children who had died from sudden infant death syndrome and other causes.

BACKGROUND--Bronchus-associated lymphoid tissue (BALT) is well characterised in rabbits and rats. In humans, however, it does not seem to be present in the healthy adult lung, although it can develop after certain microbial stimulation. METHODS--In the present study a consecutive series of lungs from 88 children who had died of sudden infant death syndrome (SIDS) and 34 control cases of comparable age were examined for the presence of BALT. RESULTS--BALT was present in 36.4% of the patients who had died of SIDS and in 44.1% of the control cases. The probability of finding BALT increased with age, with similar kinetics in both groups. CONCLUSIONS--Future studies need to define when and at what rate BALT disappears as children get older. In young children BALT may act as an entry site for antigens to initiate an immune response, as is well documented for the gut-associated lymphoid system.

FcγRIII-Mediated Production of TNF-α Induces Immune Complex Alveolitis Independently of CXC Chemokine Generation

We recently demonstrated a codominant role of C5aR and FcγRIII in the initiation of IgG immune complex-mediated inflammation in mice. In this study, we investigated the relative contribution of FcγRIII in the generation of several cytokines during experimental hypersensitivity pneumonitis/alveolitis in vivo. Induction of immune complex-alveolitis in C57BL/6 mice resulted in strong accumulation of neutrophils into the lung and enhanced chemotactic activity within bronchoalveolar lavage fluid accompanied by an increased production of the proinflammatory cytokines TNF-α and IL-1β as well as the ELR-CXC chemokines macrophage inflammatory protein-2 (MIP-2) and cytokine-induced neutrophil chemoattractant (KC). FcγRIII-deficient C57BL/6 mice (FcγRIII−/−) showed a marked reduction of the inflammatory response due to decreased production of TNF-α, IL-1β, and MIP-2. Results obtained in C57BL/6 mice either lacking the TNF-α class I receptor (TNF-αRI−/−) or treated with neutralizing anti-TNF-α mAb demonstrated an essential contribution of TNF-α for mediating IL-1β release, neutrophil influx, and hemorrhage. Surprisingly, MIP-2 and KC chemokine levels remained largely unaffected in TNF-αRI−/− mice or after functional inhibition of TNF-α. These data suggest that in immune complex alveolitis, the activation of FcγRIII may induce divergent downstream effector pathways with TNF-α acting independently of CXC chemokines to trigger the inflammatory response in C57BL/6 mice.