Distal airways are protected from goblet cell metaplasia by diminished expression of IL-13 signalling components

BACKGROUND

Increased mucus production is a critical factor impairing lung function in patients suffering from bronchial asthma, the most common chronic inflammatory lung disease worldwide.

OBJECTIVE

This study aimed at investigating whether goblet cell (GC) metaplasia and mucus production are differentially regulated in proximal and distal airways.

METHODS

Female Balb/c mice were sensitized to ovalbumin (OVA) and challenged with an OVA-aerosol on two consecutive days for 1 week (acute) or 12 weeks (chronic). Real-time RT-PCR analysis was applied on microdissected airways.

RESULTS

In acutely and chronically OVA-challenged mice, GC metaplasia and mucus production were observed in proximal but not in distal airways. In contrast, inflammation reflected by the infiltration of eosinophils and expression of the TH2-type cytokines IL-4 and IL-13 was increased in both proximal and distal airways. Abundance of IL-13Rα1 was lower in distal airways of healthy control mice. Under acute and chronic OVA-exposure, activation of IL-13Rα1-dependent signalling cascade, reflected by Spdef and Foxo3A transcription factors, was attenuated in distal compared to proximal airways.

CONCLUSION AND CLINICAL RELEVANCE

These data indicate that distal airways might be less sensitive to IL-13-induced GC metaplasia and mucus production through lower expression of IL-13Rα1 and attenuated activation of downstream signalling. This might represent a protective strategy to prevent mucus plugging of distal airways and thus impaired ventilation of attached alveoli.

CLL cells are resistant to smac mimetics because of an inability to form a ripoptosome complex

In the lymph node (LN) environment, chronic lymphocytic leukemia (CLL) cells display increased NF-κB activity compared with peripheral blood CLL cells, which contributes to chemoresistance. Antagonists of cellular inhibitor of apoptosis proteins (cIAPs) can induce apoptosis in various cancer cells in a tumor necrosis factor-α (TNFα)-dependent manner and are in preclinical development. Smac-mimetics promote degradation of cIAP1 and cIAP2, which results in TNFR-mediated apoptosis via formation of a ripoptosome complex, comprising RIPK1, Fas-associated protein with death domain, FLICE-like inhibitory protein and caspase-8. CD40 stimulation of CLL cells in vitro is used as a model to mimic the LN microenvironment and results in NF-κB activation and TNFα production. In this study, we investigated the response of CLL cells to smac-mimetics in the context of CD40 stimulation. We found that treatment with smac-mimetics results in cIAP1 and cIAP2 degradation, yet although TNFα is produced, this did not induce apoptosis. Despite the presence of all components, the ripoptosome complex did not form upon smac-mimetic treatment in CLL cells. Thus, CLL cells seem to possess aberrant upstream NF-κB regulation that prevents ripoptosome formation upon IAP degradation. Unraveling the exact molecular mechanisms of disturbed ripoptosome formation may offer novel targets for treatment in CLL.

Airway inflammation and remodeling in asthma. Lessons from interleukin 11 and interleukin 13 transgenic mice

Noninflammatory structural alterations, variously referred to as airway remodeling, are well documented in the asthmatic airway. However, the pathogenesis of these alterations, the importance of airway remodeling in generating the asthma phenotype, and the natural history of airway remodeling responses have not been adequately defined. Because exaggerated cytokine production is a characteristic feature of the asthmatic airway, we used constitutive and inducible overexpression transgenic systems to investigate the contributions that interleukin 11 (IL-11) and IL-13 might make to airway remodeling responses. These studies demonstrated that both cytokines produce responses in the murine airway with features similar to those in human asthmatic tissues. IL-11 caused airway fibrosis with the enhanced accumulation of interstitial collagens, myocytes, and myofibroblasts. IL-13 caused mucous metaplasia, enhanced mucin gene expression, enhanced tissue hyaluronic acid accumulation, and subepithelial fibrosis. Importantly, IL-11 was detected most readily in tissues from asthmatic subjects with severe airway remodeling that was similar to that seen in the IL-11 transgenic mice. In addition, IL-11 was shown to inhibit asthma-like inflammation while stimulating airway fibrosis. This suggests that IL-11 elaboration is, in part, an attempt at airway healing. Last, a novel triple transgenic system is described that allows transgene expression to be regulated in a true "on/off" manner. This system may be useful in defining the reversibility of transgene-induced airway remodeling responses.

IL-13 transgene state impairs mycobacterial (type-1) and schistosomal (type-2) antigen-elicited responses

Transgenic technology provides one approach for examining cytokine properties in vivo. This study directly tested the effect of a lung-targeted IL-13 transgene on the induction and elicitation of Th1 and Th2 cell-mediated immuno-inflammatory responses. Induction of Th1 (type 1) and Th2 (type 2) responses were tested by sensitization of IL-13 transgenics and littermates with purified protein derivative (PPD) of Mycobacterium bovis or Schistosoma mansoni eggs. Secondary elicitation of pulmonary granulomas was examined in adoptively sensitized transgenics and littermates challenged with bead-bound PPD or S. mansoni egg antigens. Parameters included lymphoid tissue cytokine profiles and granuloma sizes. Results showed that induction and elicitation of both type 1 and type 2 cytokines and granulomas were significantly abrogated in transgenics. Systemic effects were possible, as transgenic serum contained high levels of circulating IL-13. These findings support the concept that IL-13 impairs effector functions and provide novel information regarding its role in regulating Th2 cytokines.

IL-11: insights in asthma from overexpression transgenic modeling

The evolution of our understanding of IL-11 mirrors, in many ways, the problems that are faced by investigators in the post-genome era and the types of techniques that might need to be used to deal with these issues. IL-11 was discovered as a soluble factor in fibroblast supernatants that stimulated the proliferation of "IL-6-dependent" plasmacytoma cells. It was subsequently demonstrated to be an important stimulator of platelet reconstitution and a pleiotropic regulator of nonrespiratory tissues. In the lung, IL-11 is produced by a variety of structural cells and eosinophils in response to a variety of stimuli, including TGF-beta, major basic proteins, and viruses. IL-11 is also detected in exaggerated quantities at sites of virus infection. Its potential effector functions at these sites were defined with constitutive and inducible overexpression transgenic modeling systems which demonstrated that IL-11 causes nodular mononuclear infiltrates, airway remodeling with subepithelial fibrosis, airways obstruction, and airways hyperresponsiveness and can block alveolar development when expressed during development. In accord with these murine findings, IL-11 is selectively expressed in eosinophils and epithelial cells in patients with moderate and severe asthma where expression correlates directly with disease severity and inversely with FEV(1). Studies using transgenic mice also demonstrated that IL-11 inhibits antigen-induced tissue inflammation. Thus IL-11 might be an important regulator of inflammatory and remodeling responses in the asthmatic airway.

Use of the tetracycline-controlled transcriptional silencer (tTS) to eliminate transgene leak in inducible overexpression transgenic mice

The doxycycline-inducible reverse tetracycline transactivator (rtTA) is frequently used to overexpress transgenes in a temporally regulated fashion in vivo. These systems are, however, often limited by the levels of transgene expression in the absence of dox administration. The tetracycline-controlled transcriptional silencer (tTS), a fusion protein containing the tet repressor and the KRAB-AB domain of the kid-1 transcriptional repressor, is inhibited by doxycycline. We hypothesized that tTS would tighten control of transgene expression in rtTA-based systems. To test this hypothesis we generated mice in which the CC10 promoter targeted tTS to the lung, bred these mice with CC10-rtTA-interleukin 13 (IL-13) mice in which IL-13 was overexpressed in an inducible lung-specific fashion, and compared the IL-13 production and phenotypes of parental mice and the triple transgenic CC10-rtTA/tTS-IL-13 progeny of these crosses. In the CC10-rtTA-IL-13 mice, IL-13, mucus metaplasia, inflammation, alveolar enlargement, and enhanced lung volumes were noted at base line and increased greatly after doxycycline administration. In the triple transgenic tTS animals, IL-13 and the IL-13-induced phenotype could not be appreciated without doxycycline. In contrast, tTS did not alter the induction of IL-13 or the generation of the IL-13 phenotype by doxycycline. Thus, tTS effectively eliminated the baseline leak without altering the inducibility of rtTA-regulated transgenes in vivo. Optimal "off/on" regulation of transgene expression can be accomplished with the combined use of tTS and rtTA.

Carbon monoxide attenuates aeroallergen-induced inflammation in mice

Carbon monoxide (CO) generated by catalysis of heme by heme oxygenase is increased in the exhaled air of asthmatic patients. Based on recent studies demonstrating that asthma is an inflammatory disease associated with increased oxidants and that CO confers cytoprotection in oxidant-induced lung injury and inflammation, we sought to better understand the functional role of CO in asthma by using an aeroallergen model. Mice were sensitized to ovalbumin, challenged with aerosolized ovalbumin, and maintained in either CO (250 parts/million) or room air for 48 h. The differential effects of CO on bronchoalveolar lavage (BAL) fluid cell types were observed, with a marked attenuation of BAL fluid eosinophils in the CO-treated animals at 24 and 48 h. A marked reduction of the proinflammatory cytokine interleukin-5 was observed in the CO-treated mice, with no significant changes for other proinflammatory cytokines. These differential effects of CO were also observed with leukotrienes (LTs) and prostaglandins in that CO significantly decreased BAL fluid PGE2, and LTB4 but exerted negligible effect on thromboxane B2 or LTC4/D4/E4. Our data suggest a putative immunoregulatory role for CO in aeroallergen-induced inflammation in mice.

Interleukin-11 up-regulates survivin expression in endothelial cells through a signal transducer and activator of transcription-3 pathway

Interleukin-11 (IL-11) reduces injury both in vivo and in vitro, but the mechanisms are unknown. Stimulation of serum- and growth factor-deprived HUVEC with IL-11 increased survivin mRNA and protein expression levels in a dose-dependent manner, with maximal induction at 50 to 100 ng/ml of IL-11. Survivin mRNA expression peaked after 3 to 6 hours of IL-11 treatment and decreased by 24 hours. Survivin protein expression was maximal at 6 hours of treatment and remained elevated through 24 hours. Survivin induction may be mediated by activation of protein kinase B/Akt, but IL-11 failed to activate this pathway in HUVEC. IL-11 did activate signal transducer and activator of transcription (STAT)-3 and IL-11 failed to induce survivin expression in HUVEC transduced with a dominant-negative STAT3 mutant, whereas control-transduced HUVEC responded normally. An IL-11 transgene caused increased survivin mRNA expression in mice compared with control littermates. Intradermal injection of IL-11 (500 ng) into human skin xenografts on immunodeficient mice up-regulated survivin protein in microvascular endothelium and epithelial keratinocytes. We conclude that IL-11 induces expression of survivin, an antiapoptotic protein, in vitro and in vivo, and identify STAT3 as a critical mediator of this response.

Respiratory syncytial virus stimulation of vascular endothelial cell growth Factor/Vascular permeability factor

We hypothesized that respiratory syncytial virus (RSV)-induced pathologies could be mediated, in part, by vascular active cytokines elaborated during virus infection. To address this hypothesis, we determined whether RSV stimulated vascular endothelial cell growth factor (VEGF)/vascular permeability factor (VPF) elaboration in vitro. Supernatants from unstimulated A549 cells and normal human bronchial epithelial cells contained modest levels of VEGF. In contrast, supernatants from RSV-infected cells contained elevated levels of VEGF/VPF. This stimulation was seen after as little as 2 h, was still prominent after 48 h, and, by immunoblot, was specific for the 165- and 121-amino acid isoforms of VEGF/VPF. It was not associated with significant cell cytotoxicity or alterations in VEGF messenger RNA. It did, however, require new protein biosynthesis. In accordance with these findings, the 165- and 121-amino acid isoforms of VEGF/VPF were also found in the nasal washings from patients with RSV infections. These studies demonstrate that RSV is a potent stimulator of VEGF/VPF elaboration and that, in vitro, this stimulation is mediated via a noncytotoxic translational and/or post-translational biosynthetic mechanism. VEGF/VPF may play an important role in the pathogenesis of RSV-induced disorders.

Inducible targeting of IL-13 to the adult lung causes matrix metalloproteinase- and cathepsin-dependent emphysema

Cigarette smoke exposure is the major cause of chronic obstructive pulmonary disease (COPD). However, only a minority of smokers develop significant COPD, and patients with asthma or asthma-like airway hyperresponsiveness or eosinophilia experience accelerated loss of lung function after cigarette smoke exposure. Pulmonary inflammation is a characteristic feature of lungs from patients with COPD. Surprisingly, the mediators of this inflammation and their contributions to the pathogenesis and varied natural history of COPD are not well defined. Here we show that IL-13, a critical cytokine in asthma, causes emphysema with enhanced lung volumes and compliance, mucus metaplasia, and inflammation, when inducibly overexpressed in the adult murine lung. MMP-2, -9, -12, -13, and -14 and cathepsins B, S, L, H, and K were induced by IL-13 in this setting. In addition, treatment with MMP or cysteine proteinase antagonists significantly decreased the emphysema and inflammation, but not the mucus in these animals. These studies demonstrate that IL-13 is a potent stimulator of MMP and cathepsin-based proteolytic pathways in the lung. They also demonstrate that IL-13 causes emphysema via a MMP- and cathepsin-dependent mechanism(s) and highlight common mechanisms that may underlie COPD and asthma.

Endogenous and exogenous IL-6 inhibit aeroallergen-induced Th2 inflammation

Chronic Th2-dominated inflammation and exaggerated IL-6 production are characteristic features of the asthmatic airway. To understand the processes that are responsible for the chronicity of this response and the role(s) of IL-6 in the regulation of airway Th2 inflammation, we compared the responses induced by OVA in sensitized wild-type mice, IL-6 deficient (-/-) mice, and transgenic mice in which IL-6 was overexpressed in the airway (CC10-IL-6 mice). When compared with wild-type mice, IL-6-/- mice manifest exaggerated inflammation and eosinophilia, increased levels of IL-4, IL-5, and IL-13 protein and mRNA, exaggerated levels of eotaxin, JE/monocyte chemoattractant protein-1, macrophage inflammatory protein-1alpha and -2, and mRNA, increased bronchoalveolar lavage (BAL) TGF-beta1, and exaggerated airway responses to aerosolized methacholine. In contrast, CC10-IL-6 mice, on both C57BL/6 and BALB/c backgrounds, manifest diminished inflammation and eosinophilia, decreased levels of IL-4, IL-5, and IL-13 protein and mRNA, and decreased levels of bronchoalveolar lavage TGF-beta1. IL-6 also decreased the expression of endothelial VCAM-1 and airway responsiveness to methacholine in these animals. These alterations in the IL-6-/- and CC10-IL-6 mice were not associated with significant decreases or increases in the levels of IFN-gamma, respectively. These studies demonstrate that endogenous and exogenous IL-6 inhibit aeroallergen-induced Th2 inflammation and that this inhibition is not mediated by regulatory effects of IFN-gamma. IL-6 may be an important anti-inflammatory, counterregulatory, and healing cytokine in the airway.

IL-13 stimulates vascular endothelial cell growth factor and protects against hyperoxic acute lung injury

Hyperoxia is an important cause of acute lung injury. To determine whether IL-13 is protective in hyperoxia, we compared the survival in 100% O(2) of transgenic mice that overexpress IL-13 in the lung and of nontransgenic littermate controls. IL-13 enhanced survival in 100% O(2). One hundred percent of nontransgenic mice died in 4-5 days, whereas 100% of IL-13-overexpressing mice lived for more than 7 days, and many lived 10-14 days. IL-13 also stimulated VEGF accumulation in mice breathing room air, and it interacted with 100% (2) to increase VEGF accumulation further. The 164-amino acid isoform was the major VEGF moiety in bronchoalveolar lavage from transgenic mice in room air, whereas the 120- and 188-amino acid isoforms accumulated in these mice during hyperoxia. In addition, antibody neutralization of VEGF decreased the survival of IL-13-overexpressing mice in 100% (2). These studies demonstrate that IL-13 has protective effects in hyperoxic acute lung injury. They also demonstrate that IL-13, alone and in combination with 100% (2), stimulates pulmonary VEGF accumulation, that this stimulation is isoform-specific, and that the protective effects of IL-13 are mediated, in part, by VEGF.

IL-11 selectively inhibits aeroallergen-induced pulmonary eosinophilia and Th2 cytokine production

IL-11 is a pleiotropic cytokine that induces tissue remodeling with subepithelial fibrosis when expressed in the airway. Its effects on the Th2-dominated airway inflammation that is characteristic of asthma, however, are poorly understood. To characterize the effects of IL-11 on Th2 tissue inflammation, we compared the inflammatory responses elicited by OVA in sensitized mice in which IL-11 is overexpressed in a lung-specific fashion (CC10-IL-11) with that in transgene- wild-type littermate controls. Transgene- and CC10-IL-11 transgene+ mice had comparable levels of circulating Ag-specific IgE after sensitization. OVA challenge of sensitized transgene- mice caused airway and parenchymal eosinophilic inflammation, Th2 cell accumulation, and mucus hypersecretion with mucus metaplasia. Exaggerated levels of immunoreactive endothelial cell VCAM-1, mucin (Muc) 5ac gene expression and bronchoalveolar lavage and lung IL-4, IL-5, and IL-13 protein and mRNA were also noted. In contrast, OVA challenge in CC10-IL-11 animals elicited impressively lower levels of tissue and bronchoalveolar lavage inflammation, eosinophilia, and Th2 cell accumulation, and significantly lower levels of VCAM-1 and IL-4, IL-5, and IL-13 mRNA and protein. IL-11 did not cause a comparable decrease in mucus hypersecretion, Muc 5ac gene expression, or the level of expression of RANTES, monocyte chemoattractant protein-2, or monocyte chemoattractant protein-3. In addition, IL-11 did not augment IFN-gamma production demonstrating that the inhibitory effects of IL-11 were not due to a shift toward Th1 inflammation. These studies demonstrate that IL-11 selectively inhibits Ag-induced eosinophilia, Th2 inflammation, and VCAM-1 gene expression in pulmonary tissues.

Consequences of long-term inflammation. Airway remodeling

Airway inflammation may not account for all the clinical manifestations of asthma. Airway remodeling, which is thought to be a result of airway chronic inflammation, may help fill this void. Remodeling is described for fatal and nonfatal asthmatics including changes in smooth muscle, collagen deposition, noncollagenous matrix, and mucus glands. This article also reviews the correlation of airway remodeling with clinical, physiologic and biologic data, experimental models of airways remodeling, and effect of therapy on airway remodeling. Throughout, it is emphasized that the concept of airway remodeling is a dynamic process that is active and potentially progressive in asthmatic patients but that may be prevented by appropriate therapy.

Interleukin-6-induced protection in hyperoxic acute lung injury

Hyperoxic lung injury is commonly encountered in patients who require treatment with high concentrations of inspired oxygen. To determine whether interleukin (IL)-6 is protective in oxygen toxicity, we compared the effects of 100% O(2) in transgenic mice that overexpress IL-6 in the lung and transgene (-) controls. IL-6 markedly enhanced survival, with 100% of transgene (-) animals dying within 72 to 96 h, 100% of transgene (+) animals living for more than 8 d and more than 90% of transgene (+) animals living longer than 12 d. This protection was associated with markedly diminished alveolar-capillary protein leak, endothelial and epithelial membrane injury, and lung lipid peroxidation. Hyperoxia also caused cell death with DNA fragmentation in the lungs of transgene (-) animals and IL-6 markedly diminished this cytopathic response. The protective effects of IL-6 were not associated with significant alterations in the activities of copper/ zinc superoxide dismutase (SOD) or manganese SOD. They were, however, associated with the enhanced accumulation of the cell-death inhibitor Bcl-2, but not the cell-death stimulator BAX, and with the heightened accumulation of the cell-death regulator tissue inhibitor of metalloproteinase-1 (TIMP-1). These studies demonstrate that IL-6 markedly diminishes hyperoxic lung injury and that this protection is associated with a marked diminution in hyperoxia-induced cell death and DNA fragmentation. They also demonstrate that this protection is not associated with significant alterations in SOD activity, but is associated with the induction of Bcl-2 and TIMP-1.

Airway hyperresponsiveness and airway obstruction in transgenic mice. Morphologic correlates in mice overexpressing interleukin (IL)-11 and IL-6 in the lung

Understanding the sources of variation in airway reactivity and airflow is important for unraveling the pathophysiology of asthma, obstructive lung disease, and other pulmonary disorders. Transgenic expression of two closely related cytokines in the mouse lung produced opposite effects on these parameters. Interleukin (IL)-6 did not alter basal airways resistance and decreased methacholine responsiveness, whereas IL-11 caused airways obstruction and increased airway responses to methacholine. To clarify these differences we examined histologic sections and used morphometry to compare bronchiolar and parenchymal dimensions in 1- to 2-mo-old transgenic mice expressing IL-6 or IL-11 and littermate control mice. Both transgenic strains showed similar emphysema-like airspace enlargement, nodular peribronchiolar collections of mononuclear cells, thickening of airway walls, and subepithelial airway fibrosis. When compared with littermate control mice, the IL-6 mice showed an approximately 50% increase in the caliber of their bronchioles and an increase in airway wall thickness that was in proportion to the increase in the size of their airways. In contrast, the remodeling response was more robust in the IL-11 transgenic mice. It was also seen in airways with normal external and luminal diameters and thus was out of proportion to the caliber of their airways. These results support the hypothesis that structural alterations and resulting caliber changes of respiratory airways can have important effects on airway physiology and reactivity.

Prey transport kinematics in Tupinambis teguixin and Varanus exanthematicus: conservation of feeding behavior in ‘chemosensory-tongued’ lizards

Although lizards have been predicted to show extensive intraoral prey-processing behaviors, quantitative analyses of the types of prey-processing behavior they demonstrate and of their kinematics have been limited. The more basal lizard lineages (Iguanians) have undergone some study, but the prey-processing repertoires of crown taxa have not been thoroughly examined and quantitative comparisons of behaviors within or among species have not been made. In this study, the prey transport behavior of the savannah monitor (Varanus exanthematicus) and gold tegu (Tupinambis teguixin) are described. Although these two lineages have independently evolved tongues that are highly specialized for chemoreception, we found that they share the same three distinct types of transport behavior. These behavior patterns are (i) a purely inertial transport, (ii) an inertial transport with use of the tongue, and (iii) a non-inertial lingual transport. The tongue is used extensively in both the inertial and the purely lingual transport behaviors. More than 75 % of all transport behaviors involved tongue movements. These species appear to exhibit a conservation of feeding kinematics compared with patterns known for basal lizards. A hypothesis for the evolution of inertial feeding is proposed.

IL-11 expression is increased in severe asthma: association with epithelial cells and eosinophils

BACKGROUND

IL-11 is a pleiotropic cytokine produced by a variety of stromal cells. Targeted overexpression of this cytokine in mice results in a remodeling of the airways and the development of airway hyperresponsiveness and airway obstruction.

OBJECTIVES

Because these alterations mimic important pathologic and physiologic changes in the airways of some asthmatic patients, we investigated the expression of IL-11 messenger RNA (mRNA) within the airways of patients with mild to severe asthma and nonasthmatic control subjects.

METHODS

Fiberoptic bronchoscopy to obtain bronchial biopsy specimens was performed on patients with mild (n = 13), moderate (n = 10), and severe (n = 9) asthma and on nonasthmatic control subjects (n = 9).

RESULTS

These patients differed in their extent of airway fibrosis with types I and III collagens being noted in greater quantities in the biopsy specimens from the severe and moderate asthmatics than in those from controls (P <.05). IL-11 mRNA expression was observed in the epithelial and subepithelial layers of asthmatic and nonasthmatic control subjects. The number of cells within the epithelium and subepithelium expressing IL-11 mRNA was greater in those with moderate and severe asthma compared with mild asthma and nonasthmatic subjects (P <.001). There were also greater numbers of IL-11 mRNA-positive cells within the subepithelium in severe compared with moderate asthma (P <.001). Immunostaining for IL-11 within the airway tissues confirmed translation of the mRNA into IL-11-immunoreactive protein in airway epithelial cells. Colocalization of IL-11 mRNA and immunoreactivity with resident inflammatory cells demonstrated that this cytokine was also expressed by major basic protein-positive eosinophils.

CONCLUSION

These results suggest that IL-11 is involved in the chronic remodeling seen in asthmatic airways and is associated with increasing severity of the disease.

Rhinovirus regulation of IL-1 receptor antagonist in vivo and in vitro: a potential mechanism of symptom resolution

Rhinovirus (RV) upper respiratory tract infections are prototypic transient inflammatory responses. To address the mechanism of disease resolution in these infections, we determined if RV stimulated the production of the IL-1 receptor antagonist (IL-1ra) in vivo and in vitro. In contrast to IL-1alpha and IL-1beta, immunoreactive IL-1ra was readily detected in the nasal washings of normal human volunteers. Symptomatic RV infection caused a small increase in IL-1alpha, a modest increase in IL-1beta, and an impressive increase in IL-1ra. Maximal induction of IL-1alpha and IL-1beta was transiently noted 48 h after RV infection. In contrast, maximal induction of IL-1ra was prolonged appearing 48-72 h after RV infection. These time points corresponded to the periods of peak symptomatology and the onset of symptom resolution, respectively. Western analysis of nasal washings demonstrated that RV stimulated the accumulation of intracellular IL-1ra type I in all and secreted IL-1ra in a subset of volunteers. Unstimulated normal respiratory epithelial cells contained intracellular IL-1ra type I mRNA and protein. RV infection increased the intracellular levels and extracellular transport of this IL-1ra moiety without causing significant changes in the levels of IL-1ra mRNA. IL-1ra may play an important role in the resolution of RV respiratory infections. RV stimulates epithelial cell IL-1ra elaboration, at least in part, via a novel translational and/or posttranslational mechanism.

Pulmonary expression of interleukin-13 causes inflammation, mucus hypersecretion, subepithelial fibrosis, physiologic abnormalities, and eotaxin production

Interleukin (IL)-13 is a pleiotropic cytokine produced in large quantities by activated CD4(+) Th2 lymphocytes. To define further its potential in vivo effector functions, the Clara cell 10-kDa protein promoter was used to express IL-13 selectively in the lung, and the phenotype of the resulting transgenic mice was characterized. In contrast to transgene-negative littermates, the lungs of transgene-positive mice contained an inflammatory response around small and large airways and in the surrounding parenchyma. It was mononuclear in nature and contained significant numbers of eosinophils and enlarged and occasionally multinucleated macrophages. Airway epithelial cell hypertrophy, mucus cell metaplasia, the hyperproduction of neutral and acidic mucus, the deposition of Charcot-Leyden-like crystals, and subepithelial airway fibrosis were also prominently noted. Eotaxin protein and mRNA were also present in large quantities in the lungs of the transgene-positive, but not the transgene-negative, mice. IL-4, IL-5, granulocyte-macrophage colony-stimulating factor, and monocyte chemoattractant protein-5 were not similarly detected. Physiological evaluations revealed significant increases in baseline airways resistance and airways hyperresponsiveness (AHR) to methacholine in transgene-positive animals. Thus, the targeted pulmonary expression of IL-13 causes a mononuclear and eosinophilic inflammatory response, mucus cell metaplasia, the deposition of Charcot-Leyden-like crystals, airway fibrosis, eotaxin production, airways obstruction, and nonspecific AHR. IL-13 may play an important role in the pathogenesis of similar responses in asthma or other Th2-polarized tissue responses.

Effects of prolonged oxygen exposure at 1.5, 2.0, or 2.5 ATA on pulmonary function in men (predictive studies V)

As part of a study of human organ O2 tolerance, lung flow-volume and spirometric measurements were performed repeatedly before, during, and after continuous O2 exposures at 1.5, 2.0, and 2.5 ATA for average durations of 17.7, 9.0, and 5.7 h, respectively (effects of O2 breathing at 3.0 ATA for 3.5 h were reported previously; J. M. Clark, R. M. Jackson, C. J. Lambertsen, R. Gelfand, W. D. B. Hiller, and M. Unger. J. Appl. Physiol. 71: 878-885, 1991). Additional measurements of pulmonary mechanical function, gas exchange, and alveolar inflammatory cells were obtained before and after O2 exposure. Rates of pulmonary symptom development and lung volume reduction increased progressively with elevation of O2 pressure. Average rates of vital capacity reduction over a useful range of O2 pressures provided a valuable general description of pulmonary O2 tolerance in humans. However, the existence of multiple pulmonary effects of O2 toxicity and the complexity of their interactions require awareness that deviations from the average relationships may occur in different individuals or under varying conditions of O2 exposure and subsequent recovery. The associated pulmonary function deficits may represent responses to a composite of direct and indirect effects of O2 poisoning, along with related consequences and subsequent reactions to those effects.

Dexamethasone regulation of lung epithelial cell and fibroblast interleukin-11 production

Studies were undertaken to define the effects of corticosteroids on stromal cell interleukin (IL)-11 production. Unstimulated A549 epithelial-like cells produced modest amounts of IL-11, and transforming growth factor (TGF)-beta1 was a potent, dose-dependent stimulator of A549 cell IL-11 elaboration. Dexamethasone inhibited the levels of basal and TGF-beta1-stimulated IL-11 elaboration in a dose-dependent fashion. In the setting of TGF-beta1 stimulation, dexamethasone caused a >90% decrease in IL-11 production at 10(-6) M, a 50% decrease in IL-11 production at approximately 1 x 10(-9) M, and significant inhibition at 10(-10) M. This dexamethasone-induced inhibition was reversed by the glucocorticoid-receptor antagonist RU-486. Dexamethasone also inhibited respiratory syncytial virus, rhinovirus, and TGF-beta1-stimulated IL-11 production by MRC-5 lung fibroblasts. In all cases, dexamethasone caused comparable changes in IL-11 mRNA accumulation. Nuclear run-on studies demonstrated that dexamethasone caused a modest (</=40%) decrease in TGF-beta1-stimulated IL-11 gene transcription. Actinomycin D pulse-chase experiments demonstrated that dexamethasone simultaneously destabilized IL-11 mRNA. Dexamethasone also inhibited TGF-beta1-stimulated IL-11 promoter-driven luciferase activity but did not diminish activator protein-1 binding to IL-11 promoter sequences. Glucocorticoids inhibit lung cell IL-11 production via a complex mechanism that involves the inhibition of IL-11 gene transcription and the destabilization of IL-11 mRNA.

Locomotion in alligator mississippiensis: kinematic effects of speed and posture and their relevance to the sprawling-to-erect paradigm

In terms of locomotory posture, amphibians and lizards are considered to be sprawlers, mammals and dinosaurs are considered to be erect, and extant crocodilians are considered to be intermediate because they use the 'high walk', a semi-erect posture where the body is held half-way between the sprawling and erect grades during locomotion. In addition, crocodilians occasionally use a sprawling posture. Extant crocodilians, therefore, provide an interesting model in which to investigate the sprawling-to-erect transition in vertebrate evolution. This study quantifies the sprawl and high walk kinematics of the alligator Alligator mississippiensis moving at different speeds on a treadmill and compares them with kinematic data available for other vertebrates. These data allow us to examine the effects of speed on crocodilian postures and to examine how crocodilian locomotion relates to the sprawling-to-erect paradigm in vertebrate locomotion. Our results show that the crocodilian sprawl is not functionally equivalent to the primitive sprawling behaviors exhibited by salamanders and lizards. In fact, although the high walks and sprawls of alligators exhibit some kinematic differences, they are actually much more similar than expected and, essentially, the crocodilian sprawl is a lower version of a high walk and could be termed a 'low walk'. In terms of the sprawling-to-erect transition, the high walk has knee kinematics intermediate between those of birds and non-archosaurian tetrapods, but alligators increase speed in a way completely different from other terrestrial vertebrates (distal rather than proximal limb elements are used to increase speed). These kinematic data viewed in the light of the fossil and phylogenetic evidence that modern crocodilians evolved from erect ancestors suggest that modern crocodilians have secondarily evolved a variable semi-erect posture and that they are problematic as an intermediate model for the evolutionary transition from sprawling to erect postures in archosaurs.

Targeted lung expression of interleukin-11 enhances murine tolerance of 100% oxygen and diminishes hyperoxia-induced DNA fragmentation

Acute lung injury is a frequent and treatment-limiting consequence of therapy with hyperoxic gas mixtures. To determine if IL-11 is protective in oxygen toxicity, we compared the effects of 100% O2 on transgenic mice that overexpress IL-11 in the lung and transgene (-) controls. IL-11 markedly enhanced survival in 100% O2 with 100% of transgene (-) animals dying within 72-96 h and > 90% of transgene (+) animals surviving for more than 10 d. This protection was associated with markedly diminished alveolar-capillary protein leak, endothelial and epithelial membrane injury, lipid peroxidation, and pulmonary neutrophil recruitment. Significant differences in copper zinc superoxide dismutase and catalase activities were not noted and the levels of total, reduced and oxidized glutathione were similar in transgene (+) and (-) animals. Glutathione reductase, glutathione peroxidase, and manganese superoxide dismutase activities were slightly higher in transgene (+) as versus (-) mice after 100% O2 exposure, and IL-11 diminished hyperoxia-induced expression of IL-1 and TNF. Hyperoxia also caused cell death with DNA fragmentation in the lungs of transgene (-) animals and IL-11 markedly diminished this cell death response. These studies demonstrate that IL-11 markedly diminishes hyperoxic lung injury. They also demonstrate this protection is associated with small changes in lung antioxidants, diminished hyperoxia-induced IL-1 and TNF production, and markedly suppressed hyperoxia-induced DNA fragmentation.

Transforming growth factor-beta stimulates interleukin-11 transcription via complex activating protein-1-dependent pathways

Studies were undertaken to characterize the mechanism by which transforming growth factor-beta1 (TGF-beta1) stimulates epithelial cell interleukin (IL)-11 production. Nuclear run-on studies demonstrated that TGF-beta1 is a potent stimulator of IL-11 gene transcription. TGF-beta1 also stimulated the luciferase activity in cells transfected with reporter gene constructs containing nucleotides -728 to +58 of the IL-11 promoter. Studies with progressive 5' deletion constructs and site-specific mutations demonstrated that this stimulation was dependent on 2 AP-1 sites between nucleotides -100 and -82 in the IL-11 promoter. Mobility shift assays demonstrated that TGF-beta1 stimulated AP-1 protein-DNA binding to both AP-1 sites. Supershift analysis demonstrated that JunD was the major moiety contributing to AP-1-DNA binding in unstimulated cells and that c-Jun-, Fra-1-, and Fra-2-DNA binding were increased whereas JunD-DNA binding was decreased in TGF-beta1-stimulated cells. The sequence in the IL-11 promoter that contains the AP-1 sites also conferred TGF-beta1 responsiveness, in a position-independent fashion, on a heterologous minimal promoter. Thus, TGF-beta1 stimulates IL-11 gene transcription via a complex AP-1-dependent pathway that is dependent on 2 AP-1 motifs between nucleotides -100 and -82 that function as an enhancer in the IL-11 promoter.

Regulated overexpression of interleukin 11 in the lung. Use to dissociate development-dependent and -independent phenotypes

Standard overexpression transgenic approaches are limited in their ability to model waxing and waning diseases and frequently superimpose development-dependent and -independent phenotypic manifestations. We used the clara cell 10-kD protein (CC10) promoter and the reverse tetracycline transactivator (rtTA) to create a lung-specific, externally regulatable, overexpression transgenic system and used this system to express human interleukin 11 (IL-11) in respiratory structures. Gene induction could be achieved in utero, in neonates and in adult animals. Moreover, gene expression could be turned off by removal of the inducing stimulus. When gene activation was initiated in utero and continued into adulthood, subepithelial airway fibrosis, peribronchiolar mononuclear nodules, and alveolar enlargement (emphysema) were noted. Induction in the mature lung caused airway remodeling and peribronchiolar nodules, but alveolar enlargement was not appreciated. In contrast, induction in utero and during the first 14 d of life caused alveolar enlargement without airway remodeling or peribronchiolar nodules. Thus, IL-11 overexpression causes abnormalities that are dependent (large alveoli) and independent (airway remodeling, peribronchiolar nodules) of lung growth and development, and the CC10-rtTA system can be used to differentiate among these effector functions. The CC10-rtTA transgenic system can be used to model waxing and waning, childhood and growth and development-related biologic processes with enhanced fidelity.

Rhinovirus stimulation of interleukin-8 in vivo and in vitro: role of NF-kappaB

Neutrophil infiltration is a well-documented early event in the pathogenesis of rhinovirus (RV) infections. To further understand the mechanisms responsible for this neutrophilia, we determined whether interleukin (IL)-8 was present at sites of experimental RV infection in vivo and characterized the mechanism(s) by which RV stimulates IL-8 production in vitro. IL-8 was readily detectable in the nasal washings of all normal volunteers and did not increase with sham nasal inoculation. In contrast, RV infection caused a significant additional increase in nasal IL-8, the levels of which peaked 48-72 h after virus inoculation. RV was a potent stimulator of IL-8 protein production by A549 epithelial-like cells, MRC-5 fibroblasts, and normal human bronchial epithelial cells in vitro. This induction was associated with a significant increase in IL-8 mRNA accumulation and gene transcription. RV also stimulated IL-8 promoter-driven luciferase activity. This stimulation was significantly decreased by mutation of the nuclear factor (NF)-IL-6 site and was completely abrogated by mutation of the NF-kappaB site in this promoter. In addition, NF-kappaB-DNA binding activity was rapidly induced in RV-infected cells. This inducible binding was made up of p65 and, to a lesser extent, p50 NF-kappaB moieties. These studies demonstrate that IL-8 is present in normal nasal secretions and that the levels of IL-8 are further increased after RV infection. They also demonstrate that RVs are potent stimulators of IL-8 production and that this induction is mediated, at least in part, by an NF-kappaB-dependent transcriptional activation pathway. IL-8 may contribute to the pathogenesis of RV infection, and NF-kappaB activation may be a central event in RV-induced pathologies.

Interleukin-11 inhibits macrophage interleukin-12 production

IL-12 is a heterodimeric cytokine produced by phagocytic and other cells with important physiologic and pathologic properties. Regulated IL-12 production is crucial for the generation of protective Th1 responses to infectious agents. In contrast, IL-12 excess contributes to the pathogenesis of a variety of autoimmune and inflammatory disorders. To further understand the processes regulating IL-12 production, we determined whether IL-11 regulated monocyte/macrophage production of this cytokine moiety. IL-11 did not alter the IL-12 (p70) production of unstimulated THP-1 monocytic cells or human blood monocytes. It did, however, inhibit, in a dose-dependent fashion, the IL-12 production of IFN-gamma plus Staphylococcus aureus Cowan strain 1-stimulated THP-1 cells and stimulated blood monocytes. This inhibition of IL-12 protein production was associated with a proportionate decrease in IL-12 p35 and p40 mRNA accumulation. Nuclear run-on assays revealed comparable decreases in IL-12 p35 and p40 gene transcription. IL-11 did not similarly regulate monocyte/macrophage production of IL-8 or macrophage inflammatory protein-1alpha (MIP-1alpha) and IL-6 did not similarly inhibit IL-12 elaboration. These studies demonstrate that IL-11 is a potent inhibitor of monocyte/macrophage IL-12 production and that this inhibitory effect is, at least in part, transcriptionally mediated. They also demonstrate that this inhibition is not the result of a generalized suppression of macrophage effector function and that the ability to inhibit monocyte/macrophage IL-12 production is not a generalized property of all IL-6-type cytokines.

Cytokine- and virus-stimulated airway smooth muscle cells produce IL-11 and other IL-6-type cytokines

Inflammation and smooth muscle abnormalities coexist in human airway disorders, and inflammation modulates the proliferative and contractile properties of airway smooth muscle cells. To determine whether human airway smooth muscle (HASM) cells have the ability to regulate local inflammatory processes, we characterized the interleukin (IL)-6-type cytokine production of HASM cells in vitro. We demonstrated that HASM cells are potent producers of IL-11 when stimulated with IL-1 or transforming growth factor-beta 1 (TGF-beta 1) and that IL-11 levels are synergistically increased by IL-1 and TGF-beta 1 in combination. These studies also demonstrated that IL-1 and TGF-beta 1-stimulated HASM cells produce IL-6 and leukemia inhibitory factor but not oncostatin M and that respiratory syncytial virus and parainfluenza virus type 3 stimulate HASM cell IL-11 production. Finally, they demonstrate that, in all cases, the stimulation of HASM cell IL-11 elaboration is pretranslationally mediated since cytokine- and virus-induced alterations in IL-11 protein production were associated with proportionate changes in IL-11 mRNA accumulation. HASM cells are potent producers of IL-11 and other IL-6-type cytokines and may be important regulators of local airway inflammation.

Interleukin-11 inhibits macrophage interleukin-12 production

IL-12 is a heterodimeric cytokine produced by phagocytic and other cells with important physiologic and pathologic properties. Regulated IL-12 production is crucial for the generation of protective Th1 responses to infectious agents. In contrast, IL-12 excess contributes to the pathogenesis of a variety of autoimmune and inflammatory disorders. To further understand the processes regulating IL-12 production, we determined whether IL-11 regulated monocyte/macrophage production of this cytokine moiety. IL-11 did not alter the IL-12 (p70) production of unstimulated THP-1 monocytic cells or human blood monocytes. It did, however, inhibit, in a dose-dependent fashion, the IL-12 production of IFN-gamma plus Staphylococcus aureus Cowan strain 1-stimulated THP-1 cells and stimulated blood monocytes. This inhibition of IL-12 protein production was associated with a proportionate decrease in IL-12 p35 and p40 mRNA accumulation. Nuclear run-on assays revealed comparable decreases in IL-12 p35 and p40 gene transcription. IL-11 did not similarly regulate monocyte/macrophage production of IL-8 or macrophage inflammatory protein-1alpha (MIP-1alpha) and IL-6 did not similarly inhibit IL-12 elaboration. These studies demonstrate that IL-11 is a potent inhibitor of monocyte/macrophage IL-12 production and that this inhibitory effect is, at least in part, transcriptionally mediated. They also demonstrate that this inhibition is not the result of a generalized suppression of macrophage effector function and that the ability to inhibit monocyte/macrophage IL-12 production is not a generalized property of all IL-6-type cytokines.

Interleukin-11

Interleukin-11 (IL-11) is an IL-6-type cytokine that is produced by a variety of stromal cells including fibroblasts, epithelial cells and osteoblasts. It binds to a multimeric receptor complex which contains an IL-11-specific alpha subunit and a promiscuous 130 kDa beta subunit (gp130). IL-11 stimulates multiple aspects of hematopoiesis and hepatocyte production of acute phase response proteins. It also inhibits the genesis of adipocytes, activates osteoclasts, alters neural phenotype, stimulates tissue fibrosis and regulates chondrocyte, synoviocyte and B cell function. In other settings, IL-11 minimizes tissue injury. This may be the result of its ability to protect clonogenic stem cells, regulate epithelial cell proliferation, inhibit apoptosis and inhibit macrophage cytokine production. Thus, IL-11 appears to play an important role in hematopoiesis, bone metabolism and tissue remodeling and may be an important protector of mucosal surfaces.

Targeted expression of IL-11 in the murine airway causes lymphocytic inflammation, bronchial remodeling, and airways obstruction

Interleukin-11 is a pleotropic cytokine produced by lung stromal cells in response to respiratory viruses, cytokines, and histamine. To further define its potential effector functions, the Clara cell 10-kD protein promoter was used to express IL-11 and the airways of the resulting transgene mice were characterized. In contrast to transgene (-) littermates, the airways of IL-11 transgene (+) animals manifest nodular peribronchiolar mononuclear cell infiltrates and impressive airways remodeling with subepithelial fibrosis. The inflammatory foci contained large numbers of B220(+) and MHC Class II(+) cells and lesser numbers of CD3(+), CD4(+), and CD8(+) cells. The fibrotic response contained increased amounts of types III and I collagen, increased numbers of alpha smooth muscle actin and desmin-containing cells and a spectrum of stromal elements including fibroblasts, myofibroblasts, and smooth muscle cells. Physiologic evaluation also demonstrated that 2-mo-old transgene (+) mice had increased airways resistance and non-specific airways hyperresponsiveness to methacholine when compared with their transgene (-) littermates. These studies demonstrate that the targeted expression of IL-11 in the mouse airway causes a B and T cell-predominant inflammatory response, airway remodeling with increased types III and I collagen, the local accumulation of fibroblasts, myofibroblasts, and myocytes, and obstructive physiologic dysregulation. IL-11 may play an important role in the inflammatory and fibrotic responses in viral and/or nonviral human airway disorders.

IL-11 enhances survival and decreases TNF production after radiation-induced thoracic injury

We hypothesized that IL-11 would protect against radiation-induced thoracic injury. To test this hypothesis, we compared the survival of rIL-11 and vehicle-treated control mice after 25 Gy of thoracic irradiation, and initiated studies to elucidate the mechanism of the observed protection. This dose of radiation killed 50% of the control mice during the first 2 wk after irradiation. In contrast, the s.c. administration of rIL-11 resulted in significant radioprotection with 89% of the rIL-11-treated animals surviving the study interval (p &lt; 0.001). This radioprotection was at least partially specific for normal thoracic structures since rIL-11 did not alter the development or radiosensitivity of EMT6 tumor cells growing as lung metastases. TNF mRNA was not detected in normal lungs but was impressively induced after thoracic irradiation. Treatment with rIL-11 abrogated this increase. Parallel in vitro studies demonstrated that rIL-11 inhibits LPS and radiation-induced macrophage TNF protein production and mRNA accumulation. These studies demonstrate that rIL-11 reduces the mortality following thoracic irradiation, without enhancing the development or diminishing the radiosensitivity of pulmonary metastatic tumors. They also demonstrate that rIL-11 inhibits both radiation-induced TNF mRNA expression in vivo and macrophage TNF protein production and mRNA accumulation in vitro, suggesting that the radioprotective effects of rIL-11 may be mediated, at least in part, via the modulation of TNF production.

IL-11 enhances survival and decreases TNF production after radiation-induced thoracic injury

We hypothesized that IL-11 would protect against radiation-induced thoracic injury. To test this hypothesis, we compared the survival of rIL-11 and vehicle-treated control mice after 25 Gy of thoracic irradiation, and initiated studies to elucidate the mechanism of the observed protection. This dose of radiation killed 50% of the control mice during the first 2 wk after irradiation. In contrast, the s.c. administration of rIL-11 resulted in significant radioprotection with 89% of the rIL-11-treated animals surviving the study interval (p < 0.001). This radioprotection was at least partially specific for normal thoracic structures since rIL-11 did not alter the development or radiosensitivity of EMT6 tumor cells growing as lung metastases. TNF mRNA was not detected in normal lungs but was impressively induced after thoracic irradiation. Treatment with rIL-11 abrogated this increase. Parallel in vitro studies demonstrated that rIL-11 inhibits LPS and radiation-induced macrophage TNF protein production and mRNA accumulation. These studies demonstrate that rIL-11 reduces the mortality following thoracic irradiation, without enhancing the development or diminishing the radiosensitivity of pulmonary metastatic tumors. They also demonstrate that rIL-11 inhibits both radiation-induced TNF mRNA expression in vivo and macrophage TNF protein production and mRNA accumulation in vitro, suggesting that the radioprotective effects of rIL-11 may be mediated, at least in part, via the modulation of TNF production.

Eosinophil-fibroblast interactions. Granule major basic protein interacts with IL-1 and transforming growth factor-beta in the stimulation of lung fibroblast IL-6-type cytokine production

To test the hypothesis that eosinophil major basic protein (MBP) is an important regulator of fibroblast effector function, we characterized the effects of MBP on human lung fibroblast production of the IL-6-type cytokines, IL-6, IL-11, and leukemia inhibitory factor. Unstimulated fibroblasts did not produce substantial quantities of these cytokines, while IL-1 and TGF-beta(1) stimulated these cytokines in a potent fashion. MBP at doses &lt; or = 44 micrograms/ml did not stimulate IL-6-type cytokine production. It did, however, interact in a synergistic, dose- and time-dependent fashion with rIL-1-alpha and TGF-beta(1) to further increase IL-6-type cytokine elaboration. These MBP-induced increases in cytokine production were associated with proportionate alterations in mRNA accumulation. In contrast, eosinophil-derived neurotoxin did not regulate fibroblast cytokine production, and MBP did not augment fibroblast granulocyte-macrophage-CSF, or type I collagen production, or fibroblast proliferation in this culture system. The effects of MBP could not be attributed to cell cytotoxicity or contaminants in the MBP preparations. They were, however, at least partially charge mediated, since heparin abolished the effects of MBP on IL-1-stimulated cells, and the surrogate cationic molecule poly-L-arginine mimicked the stimulatory effects of MBP on fibroblast IL-6-type cytokine elaboration. These studies demonstrate that MBP interacts in a synergistic fashion with rIL-1-alpha or TGF-beta(1) to further augment fibroblast IL-6-type cytokine production. They also demonstrate that this stimulation is pretranslationally mediated and due, in part, to the cationic nature of the MBP molecule. MBP regulation of fibroblast cytokine production may play an important role in the pathogenesis of eosinophilic disorders of the airway or other organs.

Eosinophil-fibroblast interactions. Granule major basic protein interacts with IL-1 and transforming growth factor-beta in the stimulation of lung fibroblast IL-6-type cytokine production

To test the hypothesis that eosinophil major basic protein (MBP) is an important regulator of fibroblast effector function, we characterized the effects of MBP on human lung fibroblast production of the IL-6-type cytokines, IL-6, IL-11, and leukemia inhibitory factor. Unstimulated fibroblasts did not produce substantial quantities of these cytokines, while IL-1 and TGF-beta(1) stimulated these cytokines in a potent fashion. MBP at doses < or = 44 micrograms/ml did not stimulate IL-6-type cytokine production. It did, however, interact in a synergistic, dose- and time-dependent fashion with rIL-1-alpha and TGF-beta(1) to further increase IL-6-type cytokine elaboration. These MBP-induced increases in cytokine production were associated with proportionate alterations in mRNA accumulation. In contrast, eosinophil-derived neurotoxin did not regulate fibroblast cytokine production, and MBP did not augment fibroblast granulocyte-macrophage-CSF, or type I collagen production, or fibroblast proliferation in this culture system. The effects of MBP could not be attributed to cell cytotoxicity or contaminants in the MBP preparations. They were, however, at least partially charge mediated, since heparin abolished the effects of MBP on IL-1-stimulated cells, and the surrogate cationic molecule poly-L-arginine mimicked the stimulatory effects of MBP on fibroblast IL-6-type cytokine elaboration. These studies demonstrate that MBP interacts in a synergistic fashion with rIL-1-alpha or TGF-beta(1) to further augment fibroblast IL-6-type cytokine production. They also demonstrate that this stimulation is pretranslationally mediated and due, in part, to the cationic nature of the MBP molecule. MBP regulation of fibroblast cytokine production may play an important role in the pathogenesis of eosinophilic disorders of the airway or other organs.

Interleukin-11: stimulation in vivo and in vitro by respiratory viruses and induction of airways hyperresponsiveness

To address the role of IL-11 in viral airways dysfunction, we determined whether infectious agents that exacerbate asthma stimulate stromal cell IL-11 production, determined whether IL-11 could be detected at sites of viral infection and evaluated the effects of IL-11 on airway physiology. Respiratory syncytial virus (RSV), parainfluenza virus type 3 (PIV3), and rhinovirus (RV) 14 were potent stimulators while cytomegalovirus and adenovirus only weakly stimulated and herpes simplex virus type 2 and bacteria did not stimulate IL-11 elaboration. IL-11 was not detected or barely detected in nasal aspirates from children without, but was detected in aspirates from children with viral upper respiratory tract infections. The levels of IL-11 were highest in patients with clinically detectable wheezing. IL-11 also caused nonspecific airways hyperresponsiveness in BALB/c mice. These studies demonstrate that three major causes of viral-induced asthma, RSV, RV, and PIV, in contrast to other viruses and bacteria, share the ability to induce stromal cell IL-11 production. They also demonstrate that IL-11 can be detected in vivo during viral respiratory infections, that the presence of IL-11 correlates with clinical bronchospasm and that IL-11 is a potent inducer of airways hyperresponsiveness. IL-11 may be an important mediator in viral airways disorders.

Rhinovirus stimulation of interleukin-6 in vivo and in vitro. Evidence for nuclear factor kappa B-dependent transcriptional activation

To further understand the biology of rhinovirus (RV), we determined whether IL-6 was produced during RV infections and characterized the mechanism by which RV stimulates lung cell IL-6 production. In contrast to normals and minimally symptomatic volunteers, IL-6 was detected in the nasal washings from patients who developed colds after RV challenge. RV14 and RV1A, major and minor receptor group RVs, respectively, were potent stimulators of IL-6 protein production in vitro. These effects were associated with significant increases in IL-6 mRNA accumulation and gene transcription. RV was also a potent stimulator of IL-6 promoter-driven luciferase activity. This stimulation was modestly decreased by mutation of the nuclear factor (NF)-IL-6 site and abrogated by mutation of the NF-kappa B site in this promoter. An NF-kappa B-DNA binding activity, mediated by p65, p50, and p52 NF-kappa B moieties, was rapidly induced in RV-infected cells. Activator protein 1-DNA binding was not similarly altered. These studies demonstrate that IL-6 is produced during symptomatic RV infections, that RVs are potent stimulators of IL-6 elaboration, and that RV stimulation IL-6 production is mediated by an NF-kappa B-dependent transcriptional stimulation pathway. IL-6 may play an important role in the pathogenesis of RV infection, and NF-kappa B activation is likely to be an important event in RV-induced pathologies.

Cloning of a differentially expressed I kappa B-related protein

We have cloned a cDNA corresponding to a novel gene from a human epithelial cell line by subtractive hybridization and polymerase chain reaction techniques. This gene is expressed at the message level and at the protein level in a lung alveolar type II-like epithelial cell line but not in lung fibroblasts. In adult human tissues, the mRNA for this gene was detected only in the heart and the skeletal muscle, but not in the brain, placenta, whole lung, liver, or kidney. We have named this gene I kappa BR (for I kappa B-related) since its 52-kDa protein product has significant homology to the I kappa B family of proteins which function as inhibitory cytoplasmic retention proteins for the vertebrate rel/NF-kappa B transcription factors. Although the important role of NF-kappa B in gene activation in cells of the immune system is now well established, a similar role in other cell types or in vertebrate development is less clear. The deduced amino acid sequence of I kappa BR has the most significant homology to the Drosophila protein Cactus which inhibits the function of the NF-kappa B-like protein Dorsal. In electrophoretic mobility shift experiments, I kappa BR inhibited the ability of the p50:p65 NF-kappa B heterodimer to bind DNA. The DNA binding ability of the p50 homodimer but not the p65 homodimer was drastically inhibited by I kappa BR. In transfection experiments, overexpression of I kappa BR significantly inhibited NF-kappa B-dependent transcription from the Ig kappa enhancer. This new member of the I kappa B family of proteins, I kappa BR, may play an important role in regulation of NF-kappa B function in epithelial cells.