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Thursday, August 26, 2010

Vitamin D deficiency implicated in bronchopulmonary allergic aspergillosis

Will a simple, daily dose of sunshine correct the majority of our immune problems? Vitamin D deficiency has been associated with asthma, IgE levels, atopy, and obesity. Now new research has associated vitamin D deficiency with allergic bronchopulmonary aspergillosis (ABPA), which is, in turn, associated with Aspergillus fumigatus colonization in cystic fibrosis (CF) patients; however, only a small percentage of affected CF patients develop ABPA.

Kreindler et al. (J Clin Invest 2010, doi:10.1172/JCI42388) investigated this observation by comparing the Th2 profiles of ABPA CF patients and colonized, non-ABPA CF patients. They found that ABPA CF patients were characterized by a TSLP- & OX40L-driven Th2 environment. In contrast, non-ABPA CF patients did not have an excessive Th2 response and had high levels of TGF-β producing Tregs. Since vitamin D has been associated with Treg development, the authors assessed vitamin D levels in both groups; they found that ABPA patients were significantly deficient relative to the non-ABPA group. They went on to demonstrate that vitamin D deficiency lowered Tgfb mRNA and raised OX40L levels in mice. Treatment with vitamin D reversed these conditions.

Kreindler and coauthors suggested that their data demonstrated that vitamin D increases the proportion of TGF-β to OX40L favoring the induction of Tregs rather than Th2 cells.

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Thursday, August 19, 2010

Immunotherapy in asthma: a recent Cochrane review says “YES, but”

Specific immunotherapy is widely accepted in allergic rhinitis but it has long been a controversial treatment for asthma. Dr. Michael J. Abramson started the first Cochrane Collaboration review on the subject in the mid 1990s and two updates have since been published. The most recent one was published in the Cochrane Database of Systematic Reviews 2010 Issue 8 (Abramson MJ, Puy RM, Weiner JM, Injection allergen immunotherapy for asthma). The authors searched the Cochrane Airways Group Trials Register up to 2005, Dissertation Abstracts and Current Contents. Their selection criteria focused on “randomized controlled trials using various forms of allergen specific immunotherapy to treat asthma and reporting at least one clinical outcome.”
In all, 88 trials were included, of which 13 were new trials. These trials included 42 that looked at immunotherapy for house mite allergy and six that looked at multiple allergens. Their results were as follows:
Concealment of allocation was assessed as clearly adequate in only 16 of these trials. Significant heterogeneity was present in a number of comparisons. Overall, there was a significant reduction in asthma symptoms and medication, and improvement in bronchial hyper-reactivity following immunotherapy. There was a significant improvement in asthma symptom scores (standardized mean difference -0.59, 95% confidence interval -0.83 to -0.35) and it would have been necessary to treat three patients (95% CI 3 to 5) with immunotherapy to avoid one deterioration in asthma symptoms. Overall it would have been necessary to treat four patients (95% CI 3 to 6) with immunotherapy to avoid one requiring increased medication. There was no consistent effect on lung function. If 16 patients were treated with immunotherapy, one would be expected to develop a local adverse reaction. If nine patients were treated with immunotherapy, one would be expected to develop a systemic reaction (of any severity).

The authors conclude that immunotherapy is effective in asthma albeit there is a risk for local or systemic adverse effects (such as anaphylaxis). This indicates that immunotherapy in asthma should be prescribed by specialists and administered with care, in particular in patients with asthma.

Wednesday, August 4, 2010

Dust from desert storms: Another aggravation for asthma patients

Pollution, ozone, pollen, airborne animal dander, smoke, and now globally distributed mineral dust. These are just a sample of things that are demonstrated to increase the discomfort of asthma sufferers. Dust problems are not just local issues; Saharan dust is distributed across the equatorial zone all the way to Central America as well as southern North American and northern South America. Now there is evidence of significant association between global distribution of dust from these storms and asthma hospitalizations.

This interesting result comes from a study by Kanatani et al. (AJRCCM 2010, doi:10.1164/rccm.201002-0296OC) in which they use optical data from tropospheric monitoring stations in Japan from 2005 to 2009 and compare “heavy dust events,” originating in the Chinese and Mongolian deserts, with asthma hospitalizations in 8 hospitals in Toyama.

They find a significant association between heavy dust events and hospitalizations for asthma exacerbation. This is notable for the higher percentage of boys affected than girls, though the study population had fewer boys than girls. The authors also found that the effect of the dust event persisted up to 6 days after exposure.