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Wednesday, December 28, 2011

Update on biomass smoke and traffic pollution and respiratory health

Laumbach and Kipen (J Allergy Clin Immunol 2012;129: 3-11) present a report this month on the contributions of burning biomass fuels (BMF) and traffic-related air pollution (TRAP) to respiratory disease. The authors begin by noting that both TRAP and BMF burning have become critical factors for increased incidence of respiratory infections, COPD, and asthma in developed and less developed countries (DC & LDC, respectively), with both being very preventable causes.

In their introduction, they point out that global pollution monitoring has been under way for half a century, but the effects of microenvironment pollutants, such as BMF and TRAP, are less studied because of the difficulty of evaluating their impact at the level of the individual. New statistical approaches have begun to close this gap to demonstrate strong correlations between TRAP and allergic respiratory diseases as well as between BMF and COPD.

Laumbach and Kipen delve into exposure patterns for BMF burning and TRAP, commenting that the greatest burdens are on women and children in LDCs and adults and children in inner city, low socioeconomic communities in DCs. BMFs are significantly linked to lower respiratory infection in children and COPD in women in LDCs due to greater exposure to cooking and heating in poorly or unventilated households. TRAP exposure is rising in both DCs and LDCs, with LDC experiencing growth in heavy industries reliant on diesel transport.

The authors review the literature on associations of BMF with COPD, tuberculosis, and asthma, TRAP with COPD, childhood asthma and adult asthma, and indoor air pollution and respiratory infection. They briefly discuss mechanistic evidence as well as intervention studies, such as the Beijing Olympics Intervention Study and the Mexico Patsari stove study.

Laumbach and Kipen conclude by commenting on the highly political nature of reducing BMF and TRAP, pointing out that public policy and individual action will be necessary to alleviate the disparate health burden on citizens of LDCs. They urge clinicians to counsel their patients on immediate impact ways to lessen their exposure, such as improving ventilation and avoiding high traffic roadways while exercising outside.

Thursday, December 1, 2011

Chinese herbal formula shows promise for protection from peanut-allergy anaphylaxis

Traditional Chinese medicine (TCM) has been practiced in humans for thousands of years, and is growing in popularity in the US. Herbal remedies, in particular, are attractive for their low cost and favorable side effect profiles. Recently, animal research on an herbal preparation, derived from a TCM formula called Wu Mei Wan, demonstrated 100% protection from peanut allergy anaphylaxis that persisted for 6 months. In the mouse-model peanut allergy study, mast cell and basophil activation and numbers were significantly decreased as well.

In this issue, Patil et al. (J Allergy Clin Immunol 2011;128:1259-1265.e2) report promising results from an extended safety study in peanut allergic subjects of Food Allergy Herbal Formula 2 (FAHF 2), an FDA-approved botanical drug, in which they also evaluated the immunomodulatory effects of FAHF 2 on basophils. After 6 months of treatment with FAHF 2, significant reductions in basophil activation markers and circulating basophil titers were demonstrated in peripheral blood allergen stimulation tests. Patil et al. also report a concomitant decrease in eosinophils, though no change in specific IgE from baseline values. They speculate that the effect on basophils is independent of IgE-mediated basophil activation and related to FAHF 2.

They report that FAHF 2 is safe based on the absence of change from baseline of laboratory values, pulmonary function testing, and electrocardiographic results. Among 14 subjects that completed the trial, the authors report one adverse event: exacerbation of eosinophilic esophagitis. The subject stopped FAHF 2 and was able to return to the study after gastroenterologic consultation.

In conclusion, FAHF 2 therapy results in reductions in basophil activation, hyperreleasibility, and circulating titers. Patil et al. note that a double-blind, placebo-controlled efficacy study is in planning stages.

We asked senior authors Xiu-Min Li and Hugh Sampson, from Mount Sinai School of Medicine, New York, to tell us about the implications of this study and future research directions:

Li and Sampson: FAHF-2 appeared safe and well-tolerated in this long-term clinical trial of food allergic patients. Although patients were not challenged in this phase I trial, basophil activation was inhibited following therapy as anticipated, suggesting that this formulation may provide a safe immunotherapeutic option for food allergic patients. A phase II trial of FAHF-2 is now underway and if it demonstrates protection against food allergic reactions, the goal is to conduct further studies to obtain FDA approval for FAHF-2 as a prescription botanical drug.

The search for reliable predictors for developing asthma

In the context of the increasing prevalence and public health burden of asthma, reliable predictors of asthma development are being sought in order to prevent or mitigate the impact of the disease. Recent research findings of the asthma risk predictive value of infant-onset eczema combined with presence of filaggrin (FLG) null mutation and food sensitization are very promising. This month’s issue presents a report by Filipiak-Pittroff and colleagues (J Allergy Clin Immunol 2011;128:1235-1241.e5), on behalf of 2 large European birth cohort studies of nutritional and environmental factors in the development of allergic diseases, in which they sought to validate the eczema+FLG+food allergy predictors and to determine if the combination was useful in predicting persistent eczema.

Filipiak-Pittroff et al. assembled a dataset of almost 300 children with infant-onset eczema and known FLG and food allergy status and retrospectively examined the relation of these conditions with the presence of asthma and persistent eczema at age 10. The authors report that all three factors are risk factors for asthma, and their combination is highly specific, but not sensitive, for predicting asthma. This finding implies that a prediction cannot be made with sufficient confidence based on these criteria only, since there might be many false negatives, i.e. many children at risk for asthma development would not be identified correctly.

Thus, their findings did not corroborate previous research suggesting a nearly 100% predictive value for asthma development for the combined presence of early eczema, food allergy, and FLG null mutation, and shows that for a precise prediction of asthma more than these three variables are needed.

Filipiak-Pittroff et al. conclude that their results underscore the complex presentation of atopic diseases and reinforce the need to identify reliable methods for prediction.