Asthma therapies revisited: what have we learned?

Bronchodilatory and mast cell stabilising activity of Cressa cretica L.: evaluation through in vivo and in vitro experimental models

OBJECTIVE

To evaluate the effect of ethylacetate fraction (Fr-Et) and methanolic fraction (Fr-Me) obtained from Cressa cretica L.(C. cretica) L. on experimental models for bronchodilatory activity and mast cell stabilising activity.

METHODS

The effect of Fr-Et and Fr-Me were studied on acetylcholine and histamine aerosol-induced broncospasm using guinea pigs as experimental animals. Also, the effects of these fractions were evaluated on the isolated guinea pig tracheal preparations. Besides this mast cell degranulation effect was assessed using egg albumin and compound 48/80 on rat peritoneal mast cells.

RESULTS

Significant increase in preconvulsion time was observed due to pretreatment with the fractions when guinea pigs were exposed to histamine and acetylcholine aerosol. Fr-Et and Fr-Me significantly increased the preconvulsion in a dose depended manner that suggestive of bronchodilating activity. Fr-Et and Fr-Me exhibited a significant concentration dependant relaxant effect on guinea pig trachea pre-contracted with CCh, K(+) and histamine. The results revealed that Fr-Et to be more potent than Fr-Me in relaxing histamine and K(+) and calcium induced contraction than CCh induced contractions. Studies on the fractions in protecting mast cell degranulation, which were elicited by the egg albumin as well as synthetic compound 48/80 revealed both the fractions significantly protect the mast cell degranulation, which release mediators such as histamine and proinflammatory cytokines through various stimuli in a dose depended manner.

CONCLUSIONS

Thus our study established the bronchodilator activity, and mast cell stabilizing activity which are important mediators that provoke or sustain in asthma.

Medication use in children with asthma: not a child size problem

OBJECTIVE

The global burden of pediatric asthma is high. Governments and health-care systems are affected by the increasing costs of childhood asthma--in terms of direct health-care costs and indirect costs due to loss of parental productivity, missed school days, and hospitalizations. Despite the availability of effective treatment, the current use of medications in children with asthma is suboptimal. The purpose of this review is to scope the empirical literature to identify the problems associated with the use of pediatric asthma medications. The findings will help to design interventions aiming to improve the use of asthma medications among children.

METHODS

A literature search using electronic search engines (i.e., Medline, International Pharmaceutical Abstracts (IPA), PubMed, PsycINFO, and Cumulative Index to Nursing and Allied Health Literature (CINAHL)) and the search terms "asthma," "children," and "medicines" (and derivatives of these keywords) was conducted.

RESULTS

The search terms were expanded to include emergent themes arising out of search findings. Content themes relating to parents, children themselves, health-care professionals, organizational systems, and specific medications and devices were found. Within these themes, key issues included a lack of parental knowledge about asthma and asthma medications, lack of information provided to parents, parental beliefs and fears, parental behavioral problems, the high costs of medications and devices, the child's self-image, the need for more child responsibility, physician nonadherence to prescribing guidelines, "off-label" prescribing, poor understanding of teachers, lack of access to educational resources, and specific medications.

CONCLUSION

These key issues should be taken into account when modifying the development of educational tools. These tools should focus on targeting the children themselves, the parent/carers, the health-care professionals, and various organizational systems.

Asthmatic airway epithelium is intrinsically inflammatory and mitotically dyssynchronous

Asthma is an inflammatory condition for which anti-inflammatory glucocorticoids are the standard of care. However, similar efficacy has not been shown for agents targeting inflammatory cells and pathways. This suggests a noninflammatory cell contributor (e.g., epithelium) to asthmatic inflammation. Herein, we sought to define the intrinsic and glucocorticoid-affected properties of asthmatic airway epithelium compared with normal epithelium. Human primary differentiated normal and asthmatic airway epithelia were cultured in glucocorticoid-free medium beginning at -48 hours. They were pulsed with dexamethasone (20 nM) or vehicle for 2 hours at -26, -2, +22, and +46 hours. Cultures were mechanically scrape-wounded at 0 hours and exposed continuously to bromodeoxyuridine (BrdU). Cytokine secretions were analyzed using cytometric bead assays. Wound regeneration/mitosis was analyzed by microscopy and flow cytometry. Quiescent normal (n = 3) and asthmatic (n = 6) epithelia showed similar minimal inflammatory cytokine secretion and mitotic indices. After wounding, asthmatic epithelia secreted more basolateral TGF-β1, IL-10, IL-13, and IL-1β (P < 0.05) and regenerated less efficiently than normal epithelia (+48 h wound area reduction = [mean ± SEM] 50.2 ± 7.5% versus 78.6 ± 7.7%; P = 0.02). Asthmatic epithelia showed 40% fewer BrdU(+) cells at +48 hours (0.32 ± 0.05% versus 0.56 ± 0.07% of total cells; P = 0.03), and those cells were more dyssynchronously distributed along the cell cycle (52 ± 10, 25 ± 4, 23 ± 7% for G1/G0, S, and G2/M, respectively) than normal epithelia (71 ± 1, 12 ± 2, and 17 ± 2% for G1/G0, S, and G2/M, respectively). Dexamethasone pulses improved asthmatic epithelial inflammation and regeneration/mitosis. In summary, we show that inflammatory/fibrogenic cytokine secretions are correlated with dyssynchronous mitosis upon injury. Intermittent glucocorticoids simultaneously decreased epithelial cytokine secretions and resynchronized mitosis. These data, generated in an airway model lacking inflammatory cells, support the concept that epithelium contributes to asthmatic inflammation.