Primary and secondary prevention of allergic airway disease

The incidence of atopic conditions is continuing to rise. The number of primary prevention cohorts is increasing and results are becoming available. There is a lack of true secondary prevention trials, however. This article reviews the results currently available from primary and secondary prevention studies.

Oral administration of probiotic Escherichia coli after birth reduces frequency of allergies and repeated infections later in life (after 10 and 20 years)

BACKGROUND

The development of allergies is a complex in which both composition and influence of the intestinal flora play an important role. We observed in earlier studies that the presence of an orally administered probiotic Escherichia coli strain in the intestine stimulated both a serum and local antibody response, decreased the presence of pathogens, the number of infections and the need for antibiotics.

METHODS

The preventive effect of oral colonization after birth with a probiotic E. COLI strain was assessed by evaluating the results of a questionnaire both 20 years (150 full-term infants) and 10 years (77 preterm infants) after colonization.

RESULTS

Differences in occurrence of allergies in colonized and control subjects were statistically significant both after 10 and 20 years (p < 0.01). Specific serum IgE antibodies confirmed the presence of allergies in 100% of 10-year-old and 91% of 20-year-old patients with clinical symptoms of allergy. Ten years after colonization, the occurrence of repeated infections was significantly lower in colonized subjects than it was in controls (p < 0.01); 20 years later, no differences were found in these groups.

CONCLUSIONS

Intentional colonization of the intestine with E. coli after birth (offering the advantage of the first colonizer) was found to decrease the incidence of allergies and repeated infections in later life.

Alpha-melanocyte-stimulating hormone inhibits allergic airway inflammation

Alpha-melanocyte-stimulating hormone (alpha-MSH) is a neuropeptide controlling melanogenesis in pigmentary cells. In addition, its potent immunomodulatory and immunosuppressive activity has been recently described in cutaneous inflammatory disorders. Whether alpha-MSH is also produced in the lung and might play a role in the pathogenesis of inflammatory lung conditions, including allergic bronchial asthma, is unknown. Production and functional role of alpha-MSH were investigated in a murine model of allergic airway inflammation. alpha-MSH production was detected in bronchoalveolar lavage fluids. Although aerosol challenges stimulate alpha-MSH production in nonsensitized mice, this rapid and marked stimulation was absent in allergic animals. Treatment of allergic mice with alpha-MSH resulted in suppression of airway inflammation. These effects were mediated via IL-10 production, because IL-10 knockout mice were resistant to alpha-MSH treatment. This study provides evidence for a novel function of alpha-MSH linking neuroimmune functions in allergic airway inflammation.

Primary prevention of asthma and atopy during childhood by allergen avoidance in infancy: a randomised controlled study

BACKGROUND

Recent increases in the prevalence of asthma and atopy emphasise the need for devising effective methods for primary prevention in children at high risk of atopy.

METHOD

A birth cohort of genetically at risk infants was recruited in 1990 to a randomised controlled study. Allergen avoidance measures were instituted from birth in the prophylactic group (n=58). Infants were either breast fed with mother on a low allergen diet or given an extensively hydrolysed formula. Exposure to house dust mite was reduced by the use of an acaricide and mattress covers. The control group (n=62) followed standard advice as normally given by the health visitors. At age 8, all 120 children completed a questionnaire and 110 (92%) had all assessments (skin prick test, spirometry, and bronchial challenges).

RESULTS

In the prophylactic group eight children (13.8%) had current wheeze compared with 17 (27.4%) in the control group (p=0.08). Respective figures were eight (13.8%) and 20 (32.3%) for nocturnal cough (p=0.02) and 11 of 55 (20.0%) and 29 of 62 (46.8%) for atopy (p=0.003). After adjusting for confounding variables, the prophylactic group was found to be at a significantly reduced risk for current wheeze (odds ratio (OR) 0.26 (95% confidence interval (CI) 0.07 to 0.96)), nocturnal cough (OR 0.22 (95% CI 0.06 to 0.83)), asthma as defined by wheeze and bronchial hyperresponsiveness (OR 0.11 (95% CI 0.01 to 1.02)), and atopy (OR 0.21 (95% CI 0.07 to 0.62)).

CONCLUSION

Strict allergen avoidance in infancy in high risk children reduces the development of allergic sensitisation to house dust mite. Our results suggest that this may prevent some cases of childhood asthma.

Controlling indoor allergens

PURPOSE OF REVIEW

Epidemiological surveys indicate that there has been a notable increase in the prevalence of asthma and other allergic diseases in children and adults. The purpose of this review is to report and comment on recent studies about the role of allergen in primary prevention and to seek new insights on the effects of allergen control in allergic patients.

RECENT FINDINGS

This paper deals with allergen reduction in primary prevention, the effect of early exposure to pets on atopic diseases and the development of new occupational activity improving allergen control in allergic patients.

SUMMARY

The role of allergen dose involved in the onset of atopy is controversial. Studies hypothesizing that a reduction of allergen dose might reduce atopy failed to confirm the data from the Isle of Wight study and found no effect on the frequency of immunoglobulin E sensitization. This effect might nonetheless occur later in life. Other studies indicate that high doses of allergen early in life have a protective effect against cat and dog sensitization. Only one retrospective study found that cat exposure was protective against cat sensitization. A German prospective study suggested, however, that it is more probable that cat allergen exposure is harmfully related to sensitization, by increasing IgE synthesis. The effect of high doses must be clarified by further prospective studies. Accordingly, we must be very careful when giving advice on primary prevention, particularly about the protective effect of cat and dog allergens. Secondary prevention may be dramatically improved with the help of a new occupational activity: the medical indoor environment counsellor.

Respiratory syncytial virus-induced CCL5/RANTES contributes to exacerbation of allergic airway inflammation

Severe respiratory syncytial virus (RSV) infection has a significant impact on airway function and may induce or exacerbate the response to a subsequent allergic challenge. In a murine model combining early RSV infection with later cockroach allergen (CRA) challenge, we examined the role of RSV-induced CCL5/RANTES production on allergic airway responses. RSV infection increased CCL5 mRNA and protein levels, peaking at days 8 and 12, respectively. Administration of CCL5 antiserum during days 0-14 of the RSV infection did not significantly alter viral protein expression when compared to mice treated with control serum. In mice receiving the combined RSV-allergen challenge, lungs collected on day 22 exhibited significantly increased numbers of CD4- and CD8-positive T cells. This increase in T cell numbers was not observed in mice receiving alpha-CCL5. On day 43, peribronchial eosinophilia and leukotriene levels were increased in RSV-allergen mice. Pretreatment with CCL5 antiserum resulted in decreased recruitment of inflammatory cells to bronchoalveolar and peribronchial regions of the lungs and these reductions were associated with a reduction in both T cell recruitment into the bronchoalveolar space, leukotriene release and chemokine generation. Thus, CCL5 released during RSV infection has a significant effect on the inflammatory response to subsequent allergic airway challenges.

Intranasal immunotherapy is more effective than intradermal immunotherapy for the induction of airway allergen tolerance in Th2-sensitized mice

Immunotherapy (IT) by injection more readily induces clinical tolerance to stinging insects than to respiratory allergens. However, while systemic immunization induces adaptive responses systemically, the induction of mucosal immunity generally requires local Ag exposure. Taken together, these observations suggest that the poor success rate of systemic IT for asthma could be a consequence of inadequate immune modulation in the airways. In support of this position, investigations presented in this report demonstrate that allergen IT more effectively induces airway allergen tolerance in Th2-sensitized mice, when delivered by the intranasal (i.n.) vs the intradermal (i.d.) route. Moreover, compared with native allergen, allergen immunostimulatory sequence oligodeoxynucleotide conjugate proved to be a more effective i.n. IT reagent for protecting allergic mice from airway hypersensitivity responses. Furthermore, for both native allergen and allergen immunostimulatory sequence oligodeoxynucleotide conjugate, i.n. and i.d. IT delivery were similarly effective in modulating systemic immune profiles in Th2-sensitized mice, while only i.n. IT had significant immunomodulatory activity on B and T cell responses in the airways. The present investigations may be the first to suggest that i.n. IT is more effective than i.d. IT for the treatment of asthma. Furthermore, our results suggest that modulating airway rather than systemic immunity may be the more important therapeutic target for the induction of clinical tolerance to respiratory allergens.

Prevention and treatment of reactions to NSAIDs

Avoidance of ASA and other NSAIDs prevents the reactions and careful attention to clinical history along with patient education are important. However, blanket advice to avoid all NSAIDs is no longer reasonable. Except for AERD and chronic urticaria, cross-reactivity with other NSAIDs does not occur. A physician can definitively prove this by giving the patient another NSAID in their office and observing no reaction. Furthermore, for patients with AERD and chronic urticaria, they can be given the new selective COX-2 inhibitors (rofecoxib and celecoxib) without any cross-reactivity. All AERD patients can be desensitized to ASA and treated with ASA indefinitely. However, ASA desensitization in chronic urticaria is not possible. Underlying mild and moderate AERD responds well to topical and systemic corticosteroids and leukotriene modifiers. However, the severe forms of the disease should be desensitized to ASA and treated with this drug on a long term basis. In the future, new drugs that prevent eosinophil activation and chemotaxis or enhance eosinophil apoptosis are likely to be useful. Specific blockers of the second cystLT receptor would also be useful. Ultimately as the genetics of these heterogeneous disorders are unraveled, gene substitution therapy may be the ultimate answer.

[Allergic disorders of the respiratory system and skin as a public health problem]

The prevalence of allergic diseases is rapidly increasing over the last 40 years, especially in most industrialized countries of the world. Manifestations of allergic diseases are observed in about 35% of the general population. In this paper, the most frequent allergic respiratory and skin diseases are described (rhinitis, asthma, atopic eczema/dermatitis syndrome, contact eczema/dermatitis, urticaria). The most important individual and environmental factors involved in the occurrence of allergic diseases are described: genetic predisposition, exposure to allergens, environmental pollution and modern life style are discussed. The results of our investigations related to the prevalence of allergy markers in general and working population are presented. The preventive measures concerning allergic diseases are considered.

Absence of immunoglobulin E synthesis and airway eosinophilia by vaccination with plasmid DNA encoding ProDer p 1

BACKGROUND

Various studies have shown that immunization with naked DNA encoding allergens induces T helper 1(Th1)-biased non-allergic responses.

OBJECTIVE

To evaluate the polarization of the immune responses induced by vaccinations with plasmid DNA encoding the major mite allergen precursor ProDer p 1.

METHODS

A DNA vaccine was constructed on the basis of a synthetic cDNA encoding ProDer p 1 with optimized codon usage. The immunogenicity of ProDer p 1 DNA in CBA/J mice was compared with that of purified natural Der p 1 or recombinant ProDer p 1 adjuvanted with alum. Vaccinated mice were subsequently exposed to aerosolized house dust mite extracts to provoke airway inflammation. The presence of inflammatory cells was examined in bronchoalveolar lavage (BAL) fluids and allergen-specific T cell reactivity was measured.

RESULTS

Naive mice immunized with ProDer p 1 DNA developed Th1 immune responses characterized by high titres of specific IgG2a antibodies, low titres of specific IgG1 and, remarkably, the absence of anti-ProDer p 1 IgE. No specific responses were observed in animals vaccinated with the blank DNA vector. By contrast, natural Der p 1 or recombinant ProDer p 1 adsorbed to alum induced pronounced Th2 allergic responses with strong specific IgG1 and IgE titres. Spleen cells from DNA ProDer p 1-vaccinated mice secreted high levels of IFN-gamma and low production of IL-5. Conversely, both adjuvanted allergens stimulated typical Th2-type cytokine profile characterized by high and low levels of IL-5 and IFN-gamma, respectively. Whereas BAL eosinophilia was clearly observed in Der p 1-immunized animals, ProDer p 1 DNA as well as ProDer p 1 vaccinations prevented airway eosinophil infiltrations.

CONCLUSIONS

These results suggest that vaccination with DNA encoding ProDer p 1 effectively fails to induce the allergen-induced IgE synthesis and airway cell infiltration. Plasmid DNA encoding ProDer p 1 may provide a novel approach for the treatment of house dust mite allergy.

Vaccination for birch pollen allergy. Induction of affinity-matured or blocking IgG antibodies does not account for the reduced binding of IgE to Bet v 1

Specific allergy vaccination (SAV) is associated with increased levels of allergen specific IgG in serum. It is not clear, however, to what extent qualitative changes in allergen binding to IgG may be induced as well. We therefore analyzed the binding of the major allergen in pollen of birch (Betula verrucosa) (Bet v 1), the major allergen in birch pollen, to serum IgG and IgE, separately and in competition. Sera from six birch pollen-allergic patients were obtained before and after 5 years of SAV, and binding was assessed with 125I-Bet v 1. Before SAV, IgG bound more than eight times the amount of Bet v 1 compared with IgE, and together they accounted for more than 85% of the serum binding capacity. While SAV induced minimal changes in IgE binding, the IgG binding capacities increased 6-32 times. In contrast, the binding avidities (K(d) 28-40pM) changed less than 20%, pre- and post-SAV IgG provided similar inhibition of Bet v 1 binding to IgE at equimolar levels, and cross inhibition studies between IgG and IgE showed low inter-individual differences. Following SAV, all sera reduced Bet v 1 binding to CD23(+) cells, correlating with reduced binding of Bet v 1 to IgE (P<0.001). These results show that high avidity IgG of low inter-individual difference in Bet v 1 binding quality is the dominant binding factor of Bet v 1 in sera of birch pollen-allergic patients, and that SAV-induced inhibition of binding of Bet v 1 to IgE can be explained mainly or solely by increased amounts of IgG.

Implementation of statutory occupational respiratory health surveillance

Health surveillance is required by UK regulations in certain circumstances, and is usually provided through an occupational health organization. Although there are studies assessing the provision of health surveillance across the country, there are no published studies addressing the practical application of legislation, guidelines and medical research to respiratory health surveillance programmes. An audit of a multidisciplinary health surveillance programme was carried out, using review of occupational health records, occupational hygiene reports and managers' risk assessments, to compare the implementation of health surveillance in different organizations and under different contractual relationships. Sixty-six per cent of National Health Service (NHS) and 56% of industrial workplaces were able to provide risk assessments but were unable to link these with appropriate health surveillance. Twenty-seven per cent of NHS employees potentially exposed to respiratory sensitizers had baseline surveillance, compared with 87% in industry. Fifty-five per cent of Medical Research Council questionnaires were inappropriately administered by the employee themselves, rather than an interviewer as recommended. Other follow-up questionnaires in use had not been formally validated. Non-regular lung function assessment using spirometry was the predominant tool used for follow-up surveillance. There was no overall strategic approach to respiratory health surveillance in the organization studied. Health surveillance programmes should focus on disease prevention without becoming a repetitious application of unvalidated tools. Clinical governance demands quality assurance standards that will effectively implement a coordinated approach to health surveillance.

[Environmental surveys in the areas of Bitterfeld, Hettstedt and a comparative area in 1992-2000]

The aim of the environmental epidemiological study was to determine possible adverse effects on the health of children in the environmentally polluted areas of Bitterfeld and Hettstedt compared to the less polluted area of Zerbst (Eastern Germany). The changes of the health parameters were recorded together with the environmental changes during the time period of 6 years. The study design consisted of three repeated regional cross-sectional studies in 1992/93, 1995/96 and 1998/99. In total, 7,611 questionnaires could be analysed (participation rate: 89%, 75% and 75%). Children living in the most polluted area of Hettstedt had a noticeable higher risk for non-allergic respiratory diseases and symptoms compared to children living in the control area of Zerbst. From 1992 to 1999 a statistically significant decrease in the prevalences of these health outcomes was found. Children without indoor pollutants in their homes had the greatest benefit by the improvement of ambient air quality. The increase in lung function (FVC, FEV1) also underlines the improvement of the respiratory health. Children living in the polluted areas reported allergies more often (physician's diagnosis, allergy specific antibodies). The prevalence of asthma, the bronchial hyperreactivity and atopic eczema was increased within the observational period of 6 years. An increased prevalence was also shown for more severe allergic sensitisation (RAST classes > 17.5 kU/l), while the prevalence of hay fever increased slightly on a non-significant level. The burden with lead and cadmium was higher in children living in polluted areas and decreased during the study period except for 1997 where the lead concentration in blood increased according to the higher lead concentration in settled dust in Hettstedt at that time.

Bax is crucial for IFN-gamma-induced resolution of allergen-induced mucus cell metaplasia

Allergic airway responses cause proliferation of epithelial cells and mucus cell metaplasia (MCM), and the resolution of MCM involves reduction of cell numbers. The role of inflammation and apoptosis on this process was investigated in P-selectin +/+ and -/- mice sensitized and challenged with OVA by analyzing the expression and the role of regulators of apoptosis in metaplastic mucus cells. No differences were observed in MCM at 5 days of allergen exposure between +/+ and -/- mice, despite reduced IL-13 levels in -/- mice. Although IL-4 levels were similar in both -/- and +/+ mice, IL-13 and IL-5 levels had decreased and IFN-gamma levels were increased earlier in -/- compared with +/+ mice. MCM levels were decreased 4-fold at 7 days of allergen exposure in -/- mice and at 15 days in +/+ mice. The percentage of Bax-expressing mucus cells increased significantly at 7 days in -/- mice and at 10 days in +/+ mice. The Bax-positive mucus cells exhibited caspase-specific cleavage of cytokeratin 18. IFN-gamma caused Bax expression in IL-13-induced MCM in microdissected airway cultures. MCM remained significantly elevated in Bax -/- mice following 15 days of allergen exposure compared with +/+ mice, while the number of eosinophils was reduced in both Bax +/+ and -/- mice at 15 days. Together, these data demonstrate that reduced IL-13 levels were sufficient to elicit maximum MCM, that IFN-gamma induces Bax in metaplastic mucus cells, and that Bax plays a critical role in the resolution of MCM, but not in the resolution of eosinophils.

Modulation of murine allergic rhinosinusitis by CpG oligodeoxynucleotides

BACKGROUND

Allergic rhinosinusitis is characterized by eosinophilic inflammation of the upper airway, which is induced by TH-2 cytokines. CpG oligodeoxynucleotides (ODN) are known to induce TH-1 and to suppress TH-2 cytokines in a variety of settings, including murine models of asthma.

OBJECTIVE

To examine the effect of CpG ODN in a murine model of upper airway allergic inflammation and to correlate with reduction of its manifestations of sneezing and nasal scratching.

METHODS

BALB/c mice were sensitized using Ovalbumin (Ova) intraperitoneally and challenged with aerosolized Ova. CpG ODN were administered at the time of Ova sensitization. Outcomes measured included nasal symptoms, submucosal eosinophilia in the areas lined by respiratory or olfactory epithelium, and bone marrow eosinophilia. To delineate the mechanism of CpG ODN-induced suppression of eosinophilic inflammation, in vitro experiments were carried out to examine the effect of stimulation with Ova on splenocytes obtained from mice that were treated with CpG or control ODN (or no ODN) in vivo. Supernatant was collected after 72 hours of incubation and cytokines were measured by enzyme linked immunosorbent assay.

RESULTS

CpG ODN administered at the time of Ova sensitization effectively abrogated nasal symptoms and eosinophilic upper airway inflammation compared with mice treated with control ODN or with no ODN. Cytokine data revealed that Ova sensitization suppressed IFN-gamma and induced IL-4 and IL-5 compared with non-sensitized mice. CpG ODN treatment reversed these effects.

CONCLUSION

CpG ODN prevents the development of TH-2-mediated eosinophilic inflammation and symptoms in a murine model of allergic rhinosinusitis.

Clinical evaluation of the effect of anti-allergic mattress covers in patients with moderate to severe asthma and house dust mite allergy: a randomised double blind placebo controlled study

BACKGROUND

The use of anti-allergic mattress covers in patients with asthma can result in a large reduction in the level of house dust mite allergen in dust samples. Apart from a reduction in histamine induced bronchial hyperresponsiveness, there are few data on the effect of mattress covers on clinical efficacy and quality of life in patients with moderate to severe asthma.

METHODS

Thirty patients with asthma and house dust mite allergy were studied in a randomised, double blind, placebo controlled study. Before and after using anti-allergic covers for 1 year, dust was collected from the mattresses to determine concentrations of Dermatophagoides pteronyssinus (Der p 1), and bronchial hyperresponsiveness and quality of life were measured. The patients scored their symptoms (lungs and nose), morning and evening peak flow values, and rescue medication for 14 days before and after the intervention period.

RESULTS

There was a significant reduction in the concentration of Der p 1 in the dust collected from the mattresses in the actively treated group after 1 year compared with before treatment; no change was found in the placebo group. In both the actively treated and placebo groups there was no significant improvement in PC(20) histamine. Quality of life improved similarly in both groups. The symptom score of the lower airways did not significantly change in either group. A significant decrease in nasal symptom score was seen in the actively treated group compared with before treatment, but there was no significant difference between the groups. No changes in morning and evening peak flow values, peak flow variability, nor in the use of rescue medication were found in either group.

CONCLUSION

The use of anti-allergic mattress covers results in significant reductions in Der p 1 concentrations in carpet-free bedrooms. However, in patients with moderate to severe asthma, airways hyperresponsiveness and clinical parameters are not affected by this effective allergen avoidance.

Prevention of Der p2-induced allergic airway inflammation by Mycobacterium-bacillus Calmette Guerin

Epidemiologic studies suggest an inverse correlation between infection and development of allergy. The purpose of this study was to test the hypothesis whether a preexisting T helper 1 (Th1)-type immune response elicited by Mycobacterium bovis-bacillus Calmette-Guerin (BCG) immunization could suppress allergic airway inflammation induced by the mite allergen Dermatophagoides pteronyssinus group 2 (Der p2) in an animal model. C57BL/6 mice were immunized with subcutaneous injection of BCG, then intraperitoneal Der p2 emulsified in alum. Der p2-specific immunoglobulin G1 and cytokine production from splenocytes were measured after Der p2 sensitization, and pulmonary function and airway inflammation were determined after inhalation challenge with Der p2. The intraperitoneal Der p2 with alum injection was able to induce Der p2-specific immunoglobulin G1 production, which could be downregulated by the pretreatment with BCG + Der p2. The inoculation of BCG + Der p2 caused splenocytes to produce more interferon-gamma, and this level was higher than that elicited by Der p2 or buffer alone. The positive interferon-gamma-staining CD4 cells were also increased after activation by phorbol myristate acetate and ionomycin. Lung pathology examination found decreased airway inflammation (associated with the best pulmonary function and least airway desquamation) in the mice inoculated with BCG + Der p2. In this Der p2-induced allergy model, BCG inoculation with Der p2 can cause a Th1-type immune response that hinders Der p2-induced allergic sensitization and the development of airway inflammation.

Plasmid DNA encoding the respiratory syncytial virus G protein protects against RSV-induced airway hyperresponsiveness

Respiratory syncytial virus (RSV) is an important cause of childhood respiratory disease as well as exacerbations of asthma. Although previous studies have demonstrated that a DNA vaccine encoding the RSV G protein can inhibit RSV replication in mouse models of RSV infection, studies have not been performed to determine whether a DNA vaccine encoding the RSV G protein can protect against RSV induced mucus expression and airway hyperresponsiveness which was the focus of this study. The DNA-G vaccine we constructed significantly inhibited RSV viral replication, mucus expression, and importantly was associated with inhibition of RSV induced airway responsiveness.