Molecular and clinical rationale for therapeutic targeting of interleukin-5 and its receptor.

Interleukin-5 is a Th2 homodimeric cytokine involved in the differentiation, maturation, migration, development, survival, trafficking and effector function of blood and local tissue eosinophils, in addition to basophils and mast cells. The IL-5 receptor (IL-5R) consists of an IL-5-specific α subunit that interacts in conformationally dynamic ways with the receptor's ßc subunit, an aggregate of domains it shares with binding sites of IL-3 and granulocyte-macrophage colony-stimulating factor. IL-5 and IL-5R drive allergic and inflammatory immune responses characterizing numerous diseases, such as asthma, atopic dermatitis, chronic obstructive pulmonary disease, eosinophilic gastrointestinal diseases, hyper-eosinophilic syndrome, Churg-Strauss syndrome and eosinophilic nasal polyposis. Although corticosteroid therapy is the primary treatment for these diseases, a substantial number of patients exhibit incomplete responses and suffer side-effects. Two monoclonal antibodies have been designed to neutralize IL-5 (mepolizumab and reslizumab). Both antibodies have demonstrated the ability to reduce blood and tissue eosinophil counts. One additional monoclonal antibody, benralizumab (MEDI-563), has been developed to target IL-5R and attenuate eosinophilia through antibody-dependent cellular cytotoxicity. All three monoclonal antibodies are being clinically evaluated. Antisense oligonucleotide technology targeting the common ßc IL-5R subunit is also being used therapeutically to inhibit IL-5-mediated effects (TPI ASM8). Small interfering RNA technology has also been used therapeutically to inhibit the expression of IL-5 in animal models. This review summarizes the structural interactions between IL-5 and IL-5R and the functional consequences of such interactions, and describes the pre-clinical and clinical evidence supporting IL-5R as a therapeutic target.

Brain magnetic resonance imaging in adults with asthma.

BACKGROUND: In individuals with asthma, potential central nervous system changes can occur as a consequence of their asthma or therapy. Clinical trials of anti-asthmatic therapies might benefit from using magnetic resonance imaging (MRI) to assess potential brain abnormalities. PURPOSE: As part of the clinical safety evaluation of a monoclonal antibody directed against interleukin-9 for the treatment of asthma, we assessed whether brain MRI is an appropriate screening tool to evaluate potential neurotoxicity. METHODS: Brain MRIs were conducted as part of a prespecified safety evaluation in adults aged 19 to 47 years with mild to moderate asthma treated with either the investigational monoclonal antibody or placebo. An independent neuroradiologist performed a blinded review of brain MRI scans obtained at baseline before dosing and day 28 after dosing from two separate clinical studies. RESULTS: Fifteen brain MRI abnormalities were noted in 13 of 21 subjects with asthma (62%). Nonspecific deep white matter hyperintensities (24%), perivascular space (24%), and abnormal anatomic findings (14%) were noted either at baseline or follow-up. Only 8 of 21 subjects (38%) with asthma had normal brain MRI results. CONCLUSIONS: The high rate of incidental brain MRI findings suggests that these abnormalities are relatively common in patients with asthma. Thus, brain MRI may not be an appropriate screening tool to evaluate potential neurotoxicity in subjects during routine clinical studies without a baseline examination. Due to artifacts simulating lesions, an experienced radiologist should interpret all brain MRI results.

Investigational therapeutics targeting the IL-4/IL-13/STAT-6 pathway for the treatment of asthma.

Asthma is a complex, persistent, inflammatory disease characterised by airway hyperresponsiveness in association with airway inflammation. Studies suggest that regular use of high-dose inhaled corticosteroids and long-acting bronchodilators or omalizumab (a humanised monoclonal antibody that binds to immunoglobulin E and is often used as next-step therapy) may not be sufficient to provide asthma control in all patients, highlighting an important unmet need. Interleukin-4, interleukin-13, and the signal transducer and activator of transcription factor-6 are key components in the development of airway inflammation, mucus production, and airway hyperresponsiveness in asthma. Biological compounds targeting these molecules may provide a new therapeutic modality for patients with uncontrolled severe asthma. The purpose of this review is to summarise current studies of compounds targeting the interleukin-4/interleukin-13 pathway and to provide a rationale for the development of such compounds for this use.

Adding omalizumab to the therapy of adolescents with persistent uncontrolled moderate--severe allergic asthma.

OBJECTIVE: This study aimed to evaluate the effectiveness of omalizumab among adolescents with moderate-severe allergic asthma inadequately controlled with inhaled corticosteroids. PATIENTS AND METHODS: Data from patients 12 to 17 years of age were pooled from 5 placebo-controlled registration trials of omalizumab. Impact on asthma control was assessed by need for rescue bursts of oral corticosteroids, lung function, symptom scores, and unscheduled office visits. RESULTS: In adolescents (n = 146), addition of omalizumab decreased mean number of rescue bursts (0.3 vs 0.9) versus placebo; relative risk 0.47 (95% confidence interval [CI], 0.22-0.99; P = .047). At study conclusion, mean forced expiratory volume in 1 second increased 268 mL (13.8%) in omalizumab-treated subjects versus 98 mL (5.5%) for placebo (least squares mean treatment difference 146 mL [95% CI, 19.4-272.6; P = .024]). Omalizumab significantly improved asthma symptom scores and reduced unscheduled office visits. CONCLUSION: Omalizumab added to baseline therapy improves measures of asthma control in adolescents with persistent moderate-severe allergic asthma.

Upper gastrointestinal tolerability of once weekly alendronate 70 mg with concomitant non-steroidal anti-inflammatory drug use.

BACKGROUND: Both oral bisphosphonates and non-steroidal anti-inflammatory drugs have the potential to irritate the upper gastrointestinal mucosa, and are frequently used by the same patient population. AIM: To determine the rate of upper gastrointestinal adverse events with once weekly alendronate 70 mg and concomitant non-steroidal anti-inflammatory drug use. METHODS: A post hoc analysis was performed on 222 patients who received both medications concomitantly during a 3-month placebo-controlled study. A total of 450 (224 alendronate; 226 placebo) postmenopausal women and men with osteoporosis were randomized. Concomitant non-steroidal anti-inflammatory drug users were defined as patients who received > or =7 continuous days of any dose of a dual cyclo-oxygenase-1 and cyclo-oxygenase-2 inhibiting non-steroidal anti-inflammatory drug, a selective cyclo-oxygenase-2 inhibitor, or aspirin. A survival analysis was performed, and significance assessed. Logistic regression was used to assess consistency of treatment effect on rate of upper gastrointestinal adverse events across non-steroidal anti-inflammatory drug subgroups. RESULTS: Similar percentages of alendronate (52.7%) and placebo (46.0%) patients used non-steroidal anti-inflammatory drugs regularly. Among concomitant non-steroidal anti-inflammatory drug users, 11 alendronate and 11 placebo patients experienced upper gastrointestinal adverse events (9.3% and 10.8%, respectively, P = 0.744). Logistic regression revealed no significant interaction (P = 0.722) between alendronate and concomitant non-steroidal anti-inflammatory drug use. CONCLUSION: Based on this subgroup analysis, once weekly alendronate 70 mg used concomitantly with non-steroidal anti-inflammatory drugs, did not increase upper gastrointestinal adverse events relative to placebo over 3-months.

Etoricoxib reduced pain and disability and improved quality of life in patients with chronic low back pain: a 3 month, randomized, controlled trial.

BACKGROUND: Chronic low back pain (LBP) is a growing health problem. Non-steroidal anti-inflammatory drugs (NSAIDs) are used to treat this condition, but have not demonstrated efficacy beyond 2 weeks, and no studies have shown that NSAIDs produce durable improvements in disability. METHODS: To evaluate the efficacy and durability of effect of etoricoxib for chronic LBP, a randomized, double blind, placebo-controlled trial was conducted at 46 centres. Three hundred and twenty-five patients with chronic LBP requiring treatment with an NSAID or paracetamol were randomized 1:1:1 to etoricoxib 60 mg (n=109), 90 mg (n=106), or placebo (n=110), daily for 3 months. Pre-specified endpoints over 3 months included LBP intensity scale (visual analog scale 0-100 mm) time-weighted average change from baseline, the Roland-Morris Disability Questionnaire (RMDQ), the LBP bothersomeness scale, patient and investigator global assessments, and measures of quality of life. RESULTS: Both etoricoxib groups experienced significant reductions in LBP intensity at 4 weeks versus placebo [-15.15 mm and -13.03 mm for 60 and 90 mg, respectively, probability (p)<0.001 for each], which was maintained over 3 months. Treatment resulted in significant improvement from baseline compared to placebo in RMDQ scores (etoricoxib 60 mg, -2.82 and 90 mg, -2.38, p<0.001 for each) over 12 weeks and most other efficacy endpoints. There were no significant differences between treatments in incidence of adverse events (AEs) or discontinuations due to AEs. CONCLUSION: Etoricoxib provided significant relief of symptoms and disability associated with chronic LBP detected at 1 week, confirmed at 4 weeks, and maintained over 3 months. Reductions in chronic LBP severity corresponded to improvements in physical functioning and quality of life. All treatments were generally well tolerated.

Topical tacrolimus and cyclosporin A differentially inhibit early and late effector phases of cutaneous delayed-type and immunoglobulin E hypersensitivity.

Systemic and topical administration routes of tacrolimus and cyclosporin A (CsA) were compared in effects on early and late phases of elicited T-cell-mediated contact sensitivity (CS), and effects on early and late phases of cutaneous immunoglobulin E (IgE) antibody-mediated hypersensitivity responses in mice. Thus, both CS and IgE responses in the skin have an early mast-cell-dependent phase, and also a late inflammatory phase. We measured the effects of both immunosuppressants on both phases of the respective T cell versus IgE responses. Systemic administration of both agents completely suppressed CS and IgE late-phase responses, but failed to affect either early phase. In contrast, when topical CsA was used, low doses abolished the early phase of IgE responses, but even high doses did not inhibit the early phase of CS. Conversely, topical tacrolimus inhibited the early phase of CS more potently than the early phase of cutaneous IgE hypersensitivity responses. Thus, topical treatment was needed to inhibit the early phases and the two agents acted differentially, suggesting differing susceptibility of the early phases, that are probably due to different signalling mechanisms. These studies underscore the potential value of topical administration of these powerful immunosuppressive agents in the treatment of allergic diseases that exhibit features of early-phase mast-cell-dependent inflammation, and late inflammation due to mast cells or to T cells, such as atopic dermatitis or asthma, since the early phase is predominantly susceptible to topical application, while the last phase of both IgE and T-cell inflammation responds to systemic treatment with both agents.

Rofecoxib versus codeine/acetaminophen in postoperative dental pain: a double-blind, randomized, placebo- and active comparator-controlled clinical trial.

BACKGROUND: In recent studies of acute pain and primary dysmenorrhea, rofecoxib, a nonsteroidal anti-inflammatory drug that selectively targets the cyclooxygenase-2 enzyme, was found to be similar in efficacy to ibuprofen and naproxen sodium. OBJECTIVE: The purpose of this study was to determine the analgesic efficacy of a single oral dose of rofecoxib 50 mg compared with the combination of codeine 60 mg/acetaminophen 600 mg in a model of postsurgical dental pain. METHODS: In this double-blind, placebo- and active comparator-controlled, parallel-group study, patients experiencing moderate or severe pain after the surgical extraction of > or = 2 third molars, at least 1 of which was a mandibular impaction, were randomized to receive placebo, rofecoxib 50 mg, or codeine 60 mg/acetaminophen 600 mg. Patient evaluations of pain intensity, pain relief, and global assessments were recorded throughout the 24-hour period after dosing. The 2-stopwatch method was used to determine time to confirmed perceptible pain relief. The primary end point assessing overall analgesic effect was total pain relief over 6 hours (TOPAR6). Secondary end points were patient global assessment of response to therapy (PGART) at 6 hours, onset of analgesia, peak analgesic effect, and duration of analgesia. RESULTS: A total of 393 patients were enrolled; 182 received rofecoxib, 180 received codeine/acetaminophen, and 31 received placebo. The overall analgesic effect of rofecoxib 50 mg was greater than that of codeine 60 mg/acetaminophen 600 mg for TOPAR6 (12.4 vs 7.0; P < 0.001) and PGART at 6 hours (P < 0.001). The onset of analgesic effect was similar for rofecoxib and codeine/acetaminophen. Peak analgesic effect as measured by peak pain relief scores during the first 6 hours was significantly greater in the rofecoxib group compared with the codeine/acetaminophen group (P < 0.001), as was the duration of analgesic effect measured by the time to rescue analgesia (9.6 hours vs 2.3 hours, P < 0.001). Adverse events were reported in 33.0%, 46.1%, and 32.3% of patients treated with rofecoxib, codeine/acetaminophen, and placebo, respectively. The most common adverse events were nausea (6.0%, 25.0%, and 9.7%, respectively) and vomiting (3.8%, 18.3%, and 6.5%, respectively). Significantly more patients in the codeine/acetaminophen group than in the rofecoxib group experienced adverse events overall (P < 0.050) and nausea in particular (P < 0.001). CONCLUSION: In this study of moderate to severe postoperative dental pain, the analgesic efficacy of rofecoxib 50 mg was greater than that of codeine/acetaminophen, with a lower incidence of adverse events and nausea.

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.

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.

Expression of interleukin 9 in the lungs of transgenic mice causes airway inflammation, mast cell hyperplasia, and bronchial hyperresponsiveness.

Interleukin (IL)-9, a pleiotropic cytokine produced by the Th2 subset of T lymphocytes has been proposed as product of a candidate gene responsible for asthma. Its wide range of biological functions on many cell types involved in the allergic immune response suggests a potentially important role in the complex pathogenesis of asthma. To investigate the contributions of IL-9 to airway inflammation and airway hyperresponsiveness in vivo, we created transgenic mice in which expression of the murine IL-9 cDNA was regulated by the rat Clara cell 10 protein promoter. Lung selective expression of IL-9 caused massive airway inflammation with eosinophils and lymphocytes as predominant infiltrating cell types. A striking finding was the presence of increased numbers of mast cells within the airway epithelium of IL-9-expressing mice. Other impressive pathologic changes in the airways were epithelial cell hypertrophy associated with accumulation of mucus-like material within nonciliated cells and increased subepithelial deposition of collagen. Physiologic evaluation of IL-9-expressing mice demonstrated normal baseline airway resistance and markedly increased airway hyperresponsiveness to inhaled methacholine. These findings strongly support an important role for IL-9 in the pathogenesis of asthma.

Positive regulatory gamma delta T cells in contact sensitivity: augmented responses by in vivo treatment with anti-gamma delta monoclonal antibody, or anti-V gamma 5 or V delta 4.

Contact sensitivity (CS) responses, induced by skin painting with reactive haptens like picryl chloride or oxazolone, are classical examples of in vivo immunity mediated by alpha beta T cells. Our previous studies showed that gamma delta T cells were required to assist the alpha beta CS-effector T cells in the successful adoptive cell transfer of CS responses. These spleen and lymph node-derived gamma delta+ CS-assisting regulatory cells were CD3+, CD4-CD8+, non-antigen-specific, and non-MHC-restricted, and preferentially expressed V gamma 5 and V delta 4 variable regions. In the current study we show that systemic treatment of mice in vivo with anti-gamma delta mAb, produced a similar positive influence on CS responses in two different systems: i.e. active sensitization, or adoptive cell transfer. In addition to augmented CS responses produced by treatment with pan anti-gamma delta TCR mAb, anti-gamma delta-V region mAb were examined, and augmentation of CS also was produced by anti-V gamma 5 and anti-V delta 4 mAb, the V regions determined previously to be preferentially expressed on gamma delta CS-assisting cells. We speculate that the positive influence of anti-gamma delta mAb was not caused by quantitative changes in gamma delta T cells, because FACS studies demonstrated a lack of in vivo depletion of peripheral blood and lymphoid gamma delta T cells, and also no depletion of epidermal dendritic gamma delta T cells (DETC), in mice treated with anti-gamma delta TCR mAb. Instead, our data favor the hypothesis that CS-assisting gamma delta T cells can be activated in vivo by anti-gamma delta TCR mAb interacting with their gamma delta TCR, at least with the short term protocols we employed, resulting in augmentation of CS responses perhaps by releasing positively-acting factors, such as certain cytokines.

Required early complement activation in contact sensitivity with generation of local C5-dependent chemotactic activity, and late T cell interferon gamma: a possible initiating role of B cells.

Complement (C) is an important component of innate immunity, and was also shown recently to participate in induction of acquired B cell humoral immunity. In this study, we present evidence that C also participates in acquired T cell immunity. We found that C was involved in early events of the efferent elicitation phase of contact sensitivity (CS), and delayed-type hypersensitivity (DTH). Thus, CS and DTH were inhibited by administration of a C-blocker, soluble recombinant C receptor-1 (sCR1), when given 30 min before, but not 3 h after local antigen challenge. Among C components, local C5 were thought crucial to elicitation of CS, since local administration of anti-C5 monoclonal antibodies or locally injected C-depleting cobra venom factor also inhibited CS and DTH. These findings were consistent with our previous finding of the importance of C5 for CS elicitation, using congenitally C5-deficient mice. To dissect the mechanism of C dependence in CS, we demonstrated that locally increased early macrophage chemotactic activity (probably C5a) in evolving CS skin extracts, as well as late elaboration of IFN-gamma, were both inhibited by anti-C treatment. In addition, histological analysis showed that leukocyte recruitment into CS ear sites was similarly C-dependent. Furthermore, an initiating role of B cell-derived C-fixing immunoglobulin was suggested by demonstration of impaired CS responses in B cell-deficient mice. In summary, these results suggest that C was activated locally, perhaps via a B cell product, in an important early component of the stepwise events necessary to elicit CS, leading to local production of C5-dependent macrophage chemotactic activity and later IFN-gamma, and subsequently leading to cell infiltration, for development of T cell-dependent CS.

Nonatopic asthma: in vivo airway hyperreactivity adoptively transferred to naive mice by THY-1(+) and B220(+) antigen-specific cells that lack surface expression of CD3.

To investigate the cellular immune events contributing to airway hyperreactivity (AHR), we studied an in vivo mouse model induced by the hapten picryl (trinitrophenyl) chloride (PCl). Mice were immunized by cutaneous contact sensitization with PCl and airway challenged subsequently with picryl sulfonic acid (PSA) antigen (Ag). Increased airway resistance was produced late (24 h) after Ag challenge, disappeared by 48 h, and was associated with no decrease in diffusion capacity. AHR could be produced in PCl immune/ PSA challenged mice on day 7 or even, with challenge, as early as 1 d after contact sensitization, after adoptive transfer of immune cells lacking CD3(+) contact sensitivity effector T cells, or after transfer of Ag-specific lymphoid cells depleted of conventional T lymphocytes with surface determinants for CD3, CD4, CD8, TCR-beta, or TCR-delta molecules. Further experiments showed that development of AHR depended upon transfer of immune cells expressing surface membrane Thy-1 and B220 (CD45RA) determinants. We concluded that a novel population of Ag-specific lymphoid cells with a defined surface phenotype (Thy-1(+), CD3(-), CD4(-), CD8(-), TCR-alphabeta-, TCR-gammadelta-, and CD45RA+) is required in a mouse model for the development of AHR.

Human platelets can initiate T cell-dependent contact sensitivity through local serotonin release mediated by IgE antibodies.

To investigate the role of human platelets in initiating Ag-specific contact sensitivity (CS), a mouse model employing human platelets was used. Intravenous injection of immune lymphoid cells containing Ag-specific CS-effector Thy1+ B220- T cells that were depleted of CS-initiating Thy1+, B220+ cells together with human platelets presensitized in vitro with Ag-specific IgE mAb led to elicitation of CS responses in recipient mice. The fact that this response was blocked by preincubation of platelets with an irrelevant IgE or with a mixture of anti-Fc epsilonRI alpha mAb and anti-Fc epsilonRII mAb suggested that IgE Fc epsilonR on platelets were involved. When platelets that were presensitized with Ag-specific IgE mAb were incubated in vitro with specific Ag in the presence of fresh mouse serum, a significant net release of [3H]serotonin (5-hydroxytryptamine, 5-HT) was observed. Furthermore, in vitro depletion of 5-HT from platelets or in vivo pretreatment of recipients with a 5-HT2A receptor antagonist (ketanserin) abolished the IgE-dependent CS initiation mediated by platelets. These results show that human platelets can initiate T cell-dependent CS responses through IgE mAb, and this CS initiation is mediated by 5-HT released from the platelets in an Ag-specific manner.

Development of atopic dermatitis-like skin lesion with IgE hyperproduction in NC/Nga mice.

Atopic dermatitis (AD) usually develops in patients with an individual or family history of allergic diseases, and is characterized by chronic relapsing inflammation seen especially in childhood, association with IgE hyperproduction and precipitation by environmental factors. However, the exact etiology of AD has been unclear. To further explore the pathogenesis and treatment of AD, a suitable animal model is required. We found that skin lesions, which were clinically and histologically very similar to human AD, spontaneously appeared on the face, neck, ears and dorsal skin of inbred NC/Nga mice when they were raised in non-sterile (conventional) circumstances, but not under specific pathogen-free conditions. Plasma levels of total IgE in conventional NC/Nga mice were markedly elevated from 8 weeks of age, correlating with clinical skin severity of dermatitis. Immunohistochemical examination of the skin lesion showed increased numbers of mast cells and CD4+ T cells containing IL-4 necessary for IgE synthesis. Thus, NC/Nga mice suffered from dermatitis very similar to human AD with IgE hyperproduction, which may be triggered by some environmental factor(s).

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.

Delayed-type hypersensitivity in mast cell-deficient mice: dependence on platelets for expression of contact sensitivity.

Previous studies of cutaneous T cell-mediated responses in mice have obtained pharmacologic, morphologic, and immunologic evidence pointing to a critical role for local mast cells in release of the vasoactive amine serotonin (5-HT) to mediate early, initiating events that are required for elicitation of these responses. However, the role of mast cells in initiating these T cell-mediated cutaneous responses has been questioned due to the presence of relatively intact delayed-type hypersensitivity responses, such as contact sensitivity (CS), in mast cell-deficient mice whose skin contains only 1 % normal mast cell numbers. The contribution of other potential local sources of 5-HT, such as circulating platelets, at the site of a delayed-type hypersensitivity or CS response in these mast cell-deficient strains, has not been investigated. Therefore, we studied the effect of systemic platelet depletion, produced with an anti-platelet Ab, on blood and tissue levels of 5-HT, and on in vivo T cell-mediated cutaneous sensitivity responses, in W/Wv and Sl/Sld mast cell-deficient mice. The results showed that: 1) platelet depletion severely reduced whole blood 5-HT; 2) tissue levels of 5-HT, in mast cell-deficient mice, depended in large part on the presence of circulating platelets, and 3) specific depletion of platelets markedly suppressed CS responses in both W/Wv and Sl/Sld mast cell-deficient mice, and only moderately reduced CS in normal +/+ congenic mast cell-sufficient controls, but did not decrease CS in beige mice, with platelet granules that are defective in storage of 5-HT. We concluded that platelets may provide 5-HT crucial for the initiation of cutaneous T cell-mediated immune responses, such as CS.

Phenotypic and physiologic characterization of transgenic mice expressing interleukin 4 in the lung: lymphocytic and eosinophilic inflammation without airway hyperreactivity.

To investigate the contribution of interleukin-4 (IL-4) to airway inflammation in vivo and to explore directly its relationship to airway reactivity, we created transgenic mice in which the murine cDNA for IL-4 was regulated by the rat Clara cell 10 protein promoter. Expression was detected only in the lung and not in thymus, heart, liver, spleen, kidney, or uterus. The expression of IL-4 elicited hypertrophy of epithelial cells of the trachea, bronchi, and bronchioles. Hypertrophy is due, at least in part, to the accumulation of mucus glycoprotein. Histologic examination of parenchyma revealed multinucleated macrophages and occasional islands of cells consisting largely of eosinophils or lymphocytes. Analysis of lung lavage fluid revealed the presence of a leukocytic infiltrate consisting of lymphocytes, neutrophils and eosinophils. Mice expressing IL-4 had greater baseline airway resistance but did not demonstrate hyperreactivity to methacholine. Thus, the expression of IL-4 selectively within the lung elicits an inflammatory response characterized by epithelial cell hypertrophy, and the accumulation of macrophages, lymphocytes, eosinophils, and neutrophils without resulting in an alteration in airway reactivity to inhaled methacholine.