Asthma: cells and cytokines

Anastomotic disruption after large bowel resection

Anastomotic disruption is a feared and serious complication of colon surgery. Decades of research have identified factors favoring successful healing of anastomoses as well as risk factors for anastomotic disruption. However, some factors, such as the role of mechanical bowel preparation, remain controversial. Despite proper caution and excellent surgical technique, some anastomotic leaks are inevitable. The rapid identification of anastomotic leaks and the timely treatment in these cases are paramount.

Autocrine regulation of airway smooth muscle responsiveness

Bronchial asthma is characterized by airway inflammation, exaggerated airway narrowing to bronchoconstrictor agonists, and attenuated beta-adrenoceptor-mediated airway relaxation. Various cytokines/chemokines have been implicated in the pathogenesis of the airway inflammatory response, and certain cytokines, most notably including specific Th2-type cytokines and IL-1beta, have been shown to directly regulate airway smooth muscle (ASM) responsiveness. Recent evidence supports the concept that the ASM itself has the capacity to endogenously express a number of these cytokines under specific conditions of ASM sensitization. Moreover, these cytokines were found to act in an autocrine manner on the ASM to evoke the 'pro-asthmatic' phenotype of altered airway responsiveness. This cytokine-driven autocrine signaling mechanism in ASM may be triggered by either Fc receptor activation in the atopic (IgE-mediated) sensitized state or by ASM exposure to specific viral respiratory pathogens, most notably including rhinovirus. Furthermore, the autocrine-induced changes in ASM responsiveness are attributed to altered receptor-coupled transmembrane signaling in the sensitized ASM, resulting in perturbed expression and release of second messenger molecules that regulate ASM contraction and relaxation. Collectively, this evidence identifies mechanisms intrinsic to the ASM itself, including autocrine pro-inflammatory signaling and altered receptor/G protein-coupled second messenger activation, that importantly contribute to phenotypic expression of the changes in ASM responsiveness that characterize the asthmatic state.

T lymphocyte-mediated changes in airway smooth muscle responsiveness are attributed to induced autocrine release and actions of IL-5 and IL-1beta

BACKGROUND

Bidirectional stimulatory cross-talk was recently found to exist between activated T cells and airway smooth muscle (ASM) cells, a process that involves coligation of specific cellular adhesion-costimulatory molecules that results in the induction of proasthmatic-like changes in ASM responsiveness.

OBJECTIVE

The present study examined whether the cooperative intercellular signaling between activated T cells and ASM cells is coupled to the induced expression and actions of IL-5 and IL-1beta.

METHODS

Agonist-induced constrictor and relaxant responses were examined in rabbit ASM segments exposed to resting and anti-CD3-activated T cells in the absence and presence of either an anti-IL-5 receptor mAb or the recombinant human IL-1 receptor antagonist. In addition, mRNA and protein expression of IL-5 and IL-1beta were assayed under control and anti-CD3-stimulated conditions.

RESULTS

Relative to inactive T cells, incubation of ASM tissues with anti-CD3-activated T cells induced proasthmatic-like changes in agonist-mediated ASM responsiveness. This T cell-induced perturbation in ASM responsiveness was ablated by pretreating the tissues with either an anti-IL-5 receptor mAb or IL-1 receptor antagonist. Moreover, exposure of ASM cells to anti-CD3-activated T cells elicited an initial increased mRNA expression and release of IL-5, followed by an enhanced expression and release of IL-1beta, and the induced release of these cytokines was prevented in ASM cells that were pretreated with an anti-IL-5 receptor mAb.

CONCLUSION

Collectively, these observations provide new evidence demonstrating that exposure of naive ASM cells to activated T cells induces the sequential release of IL-5 and IL-1beta from the ASM cells and that the latter cytokines act in an autocrine manner to elicit the proasthmatic phenotype of altered ASM responsiveness.

Blunting airway eosinophilic inflammation results in a decreased airway neutrophil response to inhaled LPS in patients with atopic asthma: a role for CD14

Recent data demonstrate that atopic inflammation might enhance airway responses to inhaled LPS in individuals with atopic asthma by increasing CD14 expression on airway macrophages. We sought to determine whether blunting airway eosinophilic inflammation decreases CD14 expression and the subsequent airway polymorphonuclear neutrophil (PMN) response to inhaled LPS in subjects with atopic asthma. Twelve such subjects underwent a 2-week, placebo-controlled trial of inhaled steroid (440 microg fluticasone propionate [FP] twice per day); this was followed 48 hours later by an inhaled LPS (5 microg) challenge. A comparison of LPS-induced inflammatory cells in sputum, CD14 expression, and methacholine responsiveness with FP or placebo was conducted. Flow cytometry was used to analyze membrane-bound CD14 expression (mean fluorescence intensity) on sputum macrophages. We report that 48 hours before inhaled LPS challenge (baseline), FP significantly blunted airway eosinophils (cells per milligram; P =.04) and mCD14 expression (mean fluorescence intensity; P =.03) but did not decrease the number of PMNs (cells per milligram). Six hours after LPS challenge, airway PMNs and mCD14 expression were significantly decreased for FP in comparison with placebo (P =.04). Our data suggest that decreasing airway allergic inflammation with corticosteroids results in both decreased expression of CD14 on airway monocytic cells and a decreased PMN response to inhaled LPS.

Bi-directional activation between human airway smooth muscle cells and T lymphocytes: role in induction of altered airway responsiveness

Because both T lymphocyte and airway smooth muscle (ASM) cell activation are events fundamentally implicated in the pathobiology of asthma, this study tested the hypothesis that cooperative intercellular signaling between activated T cells and ASM cells mediates proasthmatic changes in ASM responsiveness. Contrasting the lack of effect of resting human T cells, anti-CD3-activated T cells were found to adhere to the surface of naive human ASM cells, increase ASM CD25 cell surface expression, and induce increased constrictor responsiveness to acetylcholine and impaired relaxation responsiveness to isoproterenol in isolated rabbit ASM tissues. Comparably, exposure of resting T cells to ASM cells prestimulated with IgE immune complexes reciprocally elicited T cell adhesion to ASM cells and up-regulated T cell expression of CD25. Extended studies demonstrated that: 1) ASM cells express mRNAs and proteins for the cell adhesion molecules (CAMs)/costimulatory molecules, CD40, CD40L, CD80, CD86, ICAM-1 (CD54), and LFA-1 (CD11a/CD18); 2) apart from LFA-1, ASM cell surface expression of the latter molecules is up-regulated in the presence of activated T cells; and 3) pretreatment of ASM cells and tissues with mAbs directed either against CD11a or the combination of CD40 and CD86 completely abrogated both the activated T cell-induced changes in expression of the above CAMs/costimulatory molecules in ASM cells and altered ASM tissue responsiveness. Collectively, these observations identify the presence of bi-directional cross-talk between activated T cells and ASM cells that involves coligation of specific CAMs/costimulatory molecules, and this cooperative intercellular signaling mediates the induction of proasthmatic-like changes in ASM responsiveness.

Secretion of adrenocorticotropic hormone induced by allergen inhalation in patients with atopic asthma

Allergen inhalation in atopic patients results in cytokines production or release of preformed cytokines, some of which are known to induce adrenocorticotropic hormone (ACTH) secretion in experimental conditions. We examined whether allergen inhalation can induce ACTH secretion in vivo. A significant elevation of ACTH levels was observed in 2 and 24 hr after allergen inhalation challenge. However, methacholine challenge with the same degree of airflow limitation did not induce ACTH elevation, indicating that this may not be due to bronchoconstriction per se. Our results indicate that allergen inhalation can trigger ACTH secretion in patients with atopic asthma.

Monocyte chemoattractant peptide-1 expression during cutaneous allergic reactions in mice is mast cell dependent and largely mediates the monocyte recruitment response

BACKGROUND

Macrophages and infiltrating monocytes comprise the largest population of cells within the airways of patients with allergic asthma. Both become activated and thus contribute to the pathologic features of allergic reactions, but the mechanism by which they are recruited has not been well documented.

OBJECTIVE

Our purpose was to assess the role of the CC chemokine monocyte chemotactic peptide-1 (MCP-1) in monocyte recruitment during allergic reactions in mice.

METHOD

We used immunohistochemistry and Northern blotting to assess MCP-1 expression, selective mast cell reconstitution of mast cell-deficient W/W(v) mice to demonstrate the mast cell dependence of MCP-1 expression and monocyte recruitment and neutralizing anti-MCP-1 antibodies to block monocyte recruitment during cutaneous allergic reactions.

RESULTS

MCP-1 was expressed largely by resident dermal cells within the allergic lesions at 4 hours after challenge, followed within several hours by an influx of monocytes; at 10 hours after challenge monocytes comprised a substantial proportion of the infiltrating cells at the nidus of the response. Mast cell-reconstituted, but not mast cell-deficient W/W(v) mice expressed MCP-1 transcripts and developed monocyte infiltrates after allergen challenge. Finally, anti-MCP-1 antibody treatments reduced by approximately 63% the influx of monocytes into the reaction sites.

CONCLUSIONS

These data clearly demonstrate the mast cell dependence of the MCP-1 expression and the monocyte influx and establish a substantial, but not exclusive, causal relationship between these 2 events.

Altered expression and action of the low-affinity IgE receptor FcepsilonRII (CD23) in asthmatic airway smooth muscle

BACKGROUND

Changes in cell surface expression of certain immunoglobulin Fc receptors have been demonstrated in leukocytes isolated from the lungs of atopic asthmatic individuals. This, together with emerging evidence that Fc receptors can also be expressed and activated in non-bone marrow-derived cell types, including airway smooth muscle (ASM), raises the hypothesis that the atopic asthmatic ASM phenotype is associated with an altered endogenous expression and action of specific Fc receptors present in the ASM itself.

OBJECTIVE

The current study addressed the above hypothesis by examining (1) whether the expression of certain key Fc receptor subtypes for IgE and IgG is altered in ASM tissue isolated from human atopic asthmatic individuals and (2) whether this altered Fc receptor expression is comparably induced in naive human ASM tissue and cultured cells after their passive sensitization with human atopic asthmatic serum or IgE immune complexes.

METHODS

Messenger RNA and cell surface protein expression of the individual IgG receptor subtypes FcgammaRI, FcgammaRII, and FcgammaRIII, as well as the IgE receptor subtypes FcepsilonRI and FcepsilonRII, were examined in human ASM tissue isolated from atopic asthmatic and control (nonatopic/nonasthmatic) individuals. In addition, we examined the effects of passive sensitization of ASM tissue and cultured ASM cells with control serum, atopic asthmatic serum, or exogenously administered IgE immune complexes on Fc receptor expression and action (ie, induction of proinflammatory cytokine release).

RESULTS

The observations demonstrate that (1) human ASM tissue expresses messenger RNA and surface protein for FcepsilonRII, as well as for all the Fcgamma receptor subtypes, (2) in contrast to unaltered Fcgamma subtype expression, however, relative to control human ASM, FcepsilonRII is significantly up-regulated in inherently asthmatic ASM tissue, (3) up-regulated expression of FcepsilonRII represents, at least in part, an inducible phenomenon that is largely attributed to IgE immune complex-coupled activation of the receptor, and (4) the latter action is associated with FcepsilonRII-induced autologous elaboration of the proinflammatory cytokine, IL-1beta, by the atopic sensitized ASM.

CONCLUSION

These observations provide new evidence that human ASM tissue expresses FcepsilonRII in addition to all 3 subtypes of Fcgamma receptors and that the expression of FcepsilonRII is selectively increased in atopic asthmatic ASM, a phenomenon associated with IgE immune complex/FcepsilonRII-mediated elaboration of IL-1beta by the ASM itself.

Autologously up-regulated Fc receptor expression and action in airway smooth muscle mediates its altered responsiveness in the atopic asthmatic sensitized state

To elucidate the role of IgE-dependent mechanisms in inducing altered airway responsiveness in the atopic asthmatic state, the expression and actions of Fc receptor activation were examined in isolated rabbit tracheal smooth muscle (TSM) tissue and cultured cells passively sensitized with sera from atopic asthmatic patients or nonatopic/nonasthmatic (control) subjects. Relative to control tissues, the atopic asthmatic-sensitized TSM exhibited significantly increased maximal isometric contractility to acetylcholine (P < 0. 01) and attenuated maximal relaxation responses and sensitivity (i.e.,-log ED50) to isoproterenol (P < 0.005). These changes in agonist responsiveness in atopic sensitized TSM were ablated by pretreating the tissues with a blocking mAb to the low affinity receptor for IgE, FcepsilonRII (i.e., CD23) or by depleting the sensitizing serum of its immune complexes. Moreover, in complimentary experiments, exogenous administration of IgE immune complexes to naive TSM produced changes in agonist responsiveness that were qualitatively similar to those obtained in the atopic asthmatic-sensitized state. Extended studies further demonstrated that, in contrast to their respective controls, atopic asthmatic serum-sensitized human and rabbit TSM tissue and cultured cells exhibited markedly induced mRNA and cell surface expression of FcepsilonRII, whereas constitutive expression of the IgG receptor subtype, FcgammaRIII, was unaltered. Finally, the up-regulated mRNA expression of FcepsilonRII observed following exposure of TSM to atopic asthmatic serum or to exogenously administered IgE immune complexes was significantly inhibited by pretreating the tissues or cells with anti-CD23 mAb. Collectively, these observations provide evidence demonstrating that the altered agonist responsiveness in atopic asthmatic sensitized airway smooth muscle is largely attributed to IgE-mediated induction of the autologous expression and activation of FcepsilonRII receptors in the airway smooth muscle itself.

Eosinophils retain their granule major basic protein in a murine model of allergic pulmonary inflammation

Accumulation of eosinophils in the lung with concomitant tissue damage are defining histopathologic features of human asthma. Through degranulation and the release of proinflammatory proteins such as major basic protein (MBP), eosinophils may perpetuate this inflammatory response. We investigated the extent of eosinophil degranulation in a murine model of allergic pulmonary inflammation. In this paradigm, the mice develop pulmonary eosinophilia, mucus hypersecretion, tissue damage, and airway edema and hyperreactivity. To evaluate the degree of eosinophil degranulation, we used a polyclonal antibody to murine MBP (mMBP) to perform dot blot analysis of bronchoalveolar lavage (BAL) cells and fluids, and immunohistochemical fluorescent analysis of lung tissue sections. After ovalbumin antigen challenge, we were unable to detect immunoreactive mMBP in the BAL fluids from either nonsensitized or sensitized mice. However, after lysis of the recoverable BAL cells, we were able to detect mMBP by immunoblot analysis, with the levels of immunoreactive mMBP directly related to the number of recoverable eosinophils. We also examined paraffin-embedded, lung tissue sections for patterns of mMBP deposition. Whereas lung sections from allergic mice revealed prominent peribronchial eosinophilia after antigen challenge, tissue sections from nonsensitized animals rarely displayed eosinophils. Despite the presence of numerous eosinophils, no immunohistologic evidence of extracellular mMBP could be found in antigen-challenged allergic mice. Furthermore, rechallenged allergic mice displayed a significant increase in the number of recruited pulmonary eosinophils but all immunoreactive mMBP was still intracellular. We conclude that the recruited pulmonary eosinophils have not substantially degranulated. These results suggest that, in this murine model of allergic inflammation, eosinophil degranulation and release of mMBP does not contribute to the observed pulmonary inflammation and airway hyperreactivity.

Cromolyn sodium prophylaxis inhibits pulmonary proinflammatory cytokines in infants at high risk for bronchopulmonary dysplasia

An imbalance of proinflammatory cytokines such as TNF-alpha, IL-1 beta, and the neutrophil chemotactic factor IL-8 and inhibitors (e.g., soluble TNF receptors and IL-1ra) in the lung during the first week of life may contribute to prolonged pulmonary inflammation and fibrosis in bronchopulmonary dysplasia (BPD). Disodium cromoglycate (DSCG) has anti-inflammatory effects in asthma, a disease with many similarities with BPD. In a prospective, randomized, blinded study, we examined whether early DSCG therapy inhibits proinflammatory cytokines in infants at risk for BPD. Twenty-six infants who were identified as high risk (> or = 75% probability) for oxygen-dependency at 28 d by a 12-h predictive score and survived 48 h were randomized to nebulized DSCG 20 mg (n = 13) or 2 cc NS (control, n = 13) every 6 h from Day 3 to Day 28. Lung lavage was collected on Day 3 (pre-study) and Day 7 and analyzed for cell count and differential and TNF-alpha, sTNFR1, sTNFR2, IL-1 beta, IL-1ra, and IL-8 concentrations. The groups' pre-study lavage cytokine concentrations were similar, but TNF-alpha and IL-8 concentrations were 3.6- and 4.9-fold lower in the DSCG group on Day 7 compared with levels in the control group. Soluble TNF receptors were unaffected by DSCG. There was a trend towards lower IL-1 beta levels in DSCG-treated infants on Day 7, but IL-1ra levels were unaffected by DSCG therapy. Three control subjects, but no DSCG-treated infants, died during the study period (p = 0.07). There were no significant differences between survivors of the two groups for oxygen-dependency at 28 d (100% control subjects; 85% DSCG). These results suggest that nebulized DSCG may exert an anti-inflammatory effect in the lungs of infants < or = 1,000 g at risk for BPD.

A discussion of the environmental influences on asthma and the role of Environmental Health Officers in combating it

Asthma is a multifactorial disease and environmental influences have long been associated with its everyday symptoms. In recent years it has been proposed that environmental factors can also influence the actual development of the disease. Underlying genetic factors may interact with these common environmental factors. Thus, the environment may be involved in both the aetiology and the symptomatic manifestations of the disease. The discussion is completed by looking at the role of local authority Environmental Health Officers (EHOs) in combating asthma.

Cytokines may give insight into mechanisms of death in sudden infant death syndrome

There are a number of postulated causes of sudden infant death syndrome, including bacterial toxins, defects in thermoregulation and hypersensitivity. This paper formulates the hypothesis that analysis of cytokine profiles in suspected sudden infant death syndrome victims may give an insight into mechanisms of death. These cytokine profiles may also help to identify specific causes of sudden infant death syndrome or indicate that different causes act in concert in individual cases.

Mast cells and T lymphocytes in chronic urticaria

Mast cells are considered to be the primary effector cells in urticaria but it is possible that lymphocytes contribute to the formation of weals by secreting histamine releasing factors. The aim of this study was to examine the population of mast cells and to quantify the T cell subsets and their activation status in delayed pressure urticaria (DPU), chronic idiopathic urticaria and normal controls. Three biopsies were obtained from each of four patients with chronic idiopathic urticaria but not DPU. Three biopsies were taken from each of 13 patients with DPU, from a combination of unchallenged skin and at 0, 2, 6, 24, 48, and 120 h after weighted steel rods (diameter 1.5 cm) had been applied to the thighs. Three biopsies were similarly obtained from each of four normal controls before an identical pressure challenge and at 6, 24 and 48 h afterwards. The chloracetate esterase stain was used to demonstrate mast cells and an alkaline phosphatase anti-alkaline phosphatase immunohistochemical technique to assess the phenotypic and activation characteristics of the T cell infiltrate. The mast cell count did not differ significantly between unchallenged skin from DPU patients and normal controls. Following a pressure challenge to the DPU patients, the number of stainable mast cells decreased significantly to a level comparable with that in spontaneous weals of chronic idiopathic urticaria. Investigation of T cell subsets showed a preponderance of CD4+ cells over CD8+ cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Immunologic analyses of peripheral leukocytes from workers at an ethical narcotics manufacturing facility

Little information exists about possible adverse health effects associated with workplace exposure to opiate compounds. We have previously reported opiate-specific IgG antibodies, positive epicutaneous tests, and pulmonary function decrements in workers exposed occupationally to opiates. In the present work, we extended these findings to investigate the effect of occupational opiate exposure on lymphocyte subpopulations and mitogen-induced lymphoblastogenesis. Thirty-three opiate-exposed workers and 8 nonexposed control workers were evaluated for lymphocyte subpopulation absolute numbers and percentages, by evaluating cell surface antigen expression with flow cytometry. A complete blood count with differential, common clinical chemistry parameters, and serum immunoglobulin levels were also evaluated. Opiate-exposed workers showed significantly (p < .05) increased absolute numbers and percentages of HLA-DR+ cells (MHC class II histocompatibility antigen), significantly (p < .01) decreased percentages of T helper-inducer (CD4+) cells, and significantly (p < .05) decreased numbers of basophils, compared with nonexposed opiate workers from the same factory. A trend toward reduction in the T helper-inducer (CD4+)/T cytotoxic-suppressor (CD8+) lymphocyte ratio was also evident. There was also a significant decrease in lymphocyte activity stimulated by pokeweed mitogen (p < .05) in opiate-exposed workers. These data indicate that occupational opiate exposure may change the number and types of circulating peripheral blood leukocytes, or alternatively, alter the expression of receptors on the surface of these cells. In addition, occupational opiate exposure appears to decrease the sensitivity of B-cells to pokeweed mitogen stimulation.(ABSTRACT TRUNCATED AT 250 WORDS)

Childhood asthma: diagnosis and treatment

This discussion of asthma management should be regarded as providing guidelines, not dogma. The underlying principles of asthma management include recognition of the variability of the disease and the importance of the underlying inflammatory condition. Clinical assessment is not enough and objective monitoring with PEFR or spirometry provides important data. The treatment protocols require individualization. It is important that the patient and family are team members working together with the medical staff toward a goal of good asthma management. In the discussion of the management of asthma, much emphasis was placed on spirometry and home measurement of PEFR. Office use of spirometry is now the norm for asthma management. Providing asthmatic patients with peak flow meters and instructions in their use is part of the routine care of asthma. Instruction of the patient and family in the proper use of medications is paramount. The MDI devices need to be prescribed with careful instructions regarding their use. When the patient comes in for follow-up, part of the examination should include the patient's demonstration of how he uses this device. Discussion of the proper and safe use of bronchodilators is important. Overuse of inhaled bronchodilators may be a reflection of increasing asthma or, at the very least, evidence that the patient does not understand appropriate treatment of asthma. If a patient is dependent on regular use of an inhaled beta agent, it is likely that he would benefit from therapy directed at the underlying inflammation of asthma. The patient and the family should understand the purpose of each medication, the side effects, and the risks and benefits of their use. In particular, if steroid medications are necessary, the reasons for their use should be explained. Carefully matching the severity of the asthma with the therapeutic protocols provides an organized approach to asthma treatment. Avoiding triggers of asthma and controlling the environmental exposure to potential triggers leads to lower medication requirements and less lability. Offering the family written instructions to cope with changes in the child's condition, based on assessment of clinical and PEFR observations, allows them more autonomy and comfort in the day-to-day care of the asthmatic child.