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.