Antibiotic use in early childhood and the development of asthma

Does the microbiota regulate immune responses outside the gut?

Perturbations in the gastrointestinal (GI) microbiota composition that occur as a result of antibiotics and diet in "westernized" countries are strongly associated with allergies and asthma ("hygiene hypothesis"). The microbiota ("microflora") plays a crucial role in the development of mucosal tolerance, including the airways. Significant attention has been focused on the role of the microbiota in GI development, immune adaptation and initiation of GI inflammatory diseases. This review covers the post-developmental functions that the microbiota plays in regulating immunological tolerance to allergen exposure outside the GI tract and proposes the question: is the microbiota a major regulator of the immune system?

Use of antibacterials in infancy: clinical implications for childhood asthma and allergies

Evidence from experimental studies in rodents and results from epidemiologic studies with a retrospective design suggest a possible causal association between antibacterial use in early childhood and asthma. Such an association is thought to be mediated by antibacterial-induced alterations in the intestinal flora, leading to a skewing of the immune system of young children toward an atopic phenotype. However, results from recently conducted prospective studies suggest that the previously observed association between antibacterial use in early childhood and asthma is not one of 'cause and effect' but rather that frequent antibacterial use in early childhood may be a marker of an increased risk of being diagnosed with asthma later in childhood. Although antibacterials should not be used excessively in young children, their use in early childhood is not likely to explain the increased prevalence of asthma and allergies in children in industrialized countries.

Prevalence of skin disorders in school children in Ibadan, Nigeria

Although skin diseases are common in children, there are very few population-based studies in West Africa. Recently, there has been considerable emphasis on hygiene and socio-economic impact on the incidence of allergic disorders in children. We determined the prevalence of skin diseases in a public primary school in Ibadan (southwest Nigeria). A questionnaire for assessing factors associated with the prevalence of diseases was completed, and a complete physical examination was carried out on 1066 students. The study included 529 (49.6%) boys and 537 (50.4%) girls with a mean age of 8.8 +/- 2.5 years. The mean family size of the subjects was 6.7 +/- 2.3 while the mean number of rooms in their homes was 2.6 +/- 1.45. Infectious dermatosis was commonly observed. Of 375 children with a skin lesion, 162 (15.2%) had dermatophytosis, most often tinea capitis, 50 (4.7%) had pityriasis versicolor, and 50 (4.7%) had scabies. Other dermatoses observed included papular urticaria in 35 (3.3%) and angular cheilitis in 27 (2.5%) children. One or more melanocytic nevi were found in 40 (3.8%) children while 138 (12.9%) and 77 (7.25%) had tribal and scarification marks, respectively. Atopic eczema and viral warts were virtually absent. We concluded that fungal infections and scabies were the most common skin diseases in our study population, whereas allergic illnesses were nearly absent.

Commonly Used Drugs Impair Oral Tolerance in Mice

Ibuprofen and antibiotics are commonly prescribed during early childhood. When given to mice at the time at which oral tolerance is induced, both treatments affect either the induction or the maintenance of oral tolerance. These results suggest that the coadministration of these and similarly acting drugs should be considered cautiously for infants at risk of allergy.

Antibiotic use in the first year of life and asthma in early childhood

BACKGROUND

An association between antibiotic use in early life and asthma in childhood has been reported in five retrospective studies and one longitudinal study.

OBJECTIVE

To examine the relation between the use of oral antibiotics in the first year of life and asthma in early childhood.

METHODS

Longitudinal follow-up of 4408 children enrolled in a health maintenance organization (HMO) from birth to the age of 5 years.

RESULTS

After adjusting for sex and illnesses of the lower respiratory tract (LRIs), we found a significant association between antibiotic use in the first year of life and asthma between the ages of 1 and 2 years (odds ratio (OR) for 1-2 vs. no courses of antibiotics=1.9, 95% confidence interval (CI)=1.3-2.7; OR for 3-4 vs. no courses of antibiotics=1.6, 95% CI=1.1-2.4; OR for at least 5 vs. no courses of antibiotics=2.1, 95% CI=1.5-3.2). After adjustment for sex and LRIs in the first year of life, there was no significant association between antibiotic use in the first year of life and asthma that was initially diagnosed between the ages of 2 and 5 years and that persisted up to the age of 5 years (OR for 1-2 vs. no courses of antibiotics=1.1, 95% CI=0.8-1.4; OR for 3-4 vs. no courses of antibiotics=1.3, 95% CI=0.9-1.8; OR for at least 5 vs. no courses of antibiotics=1.0, 95% CI=0.7-1.4). Conclusions Our findings do not support the hypothesis that antibiotic use in early life is associated with the subsequent development of asthma in childhood but rather suggest that frequent antibiotic use in early life is more common among asthmatic children.

Infections, medication use, and the prevalence of symptoms of asthma, rhinitis, and eczema in childhood

BACKGROUND

The "hygiene hypothesis" postulates that infections during infancy may protect against asthma and atopy. There is also some evidence that antibiotic and/or paracetamol use may increase the risk of asthma.

METHODS

The study measured the association between infections, and medication use early in life and the risk of asthma at age 6-7 years. It involved 1584 children who had been notified to public health services with serious infections at age 0-4 years, and 2539 children sampled from the general population. For both groups, postal questionnaires were completed by parents.

RESULTS

There was little difference in the prevalence of current wheezing between the childhood infections group (prevalence = 23.5%) and the general population group (prevalence = 24.3%). There was also little difference whether the major site of infection was gastrointestinal (prevalence = 24.1%), invasive (prevalence = 24.6%) or respiratory (prevalence = 21.1%). However, in both groups, there were associations with antibiotic (OR = 1.78, 95% CI 1.49 to 2.14) or paracetamol (OR = 1.38, 95% CI 1.04 to 1.83) use in the first year of life or recent paracetamol use (OR = 2.10, 95% CI 1.78 to 2.49) and current wheezing. There was a weak protective effect of childhood infections in children who had not used antibiotics in the first year of life (OR = 0.78, 95% CI 0.55 to 1.10).

CONCLUSIONS

These findings are consistent with other evidence that antibiotic use early in life may increase the risk of asthma. They are also consistent with some preliminary evidence associating paracetamol use with an increased risk of asthma. Any protective effect of notifiable childhood infections was weak.

Influence of MMR-vaccinations and diseases on atopic sensitization and allergic symptoms in Swiss schoolchildren

The prevalence of asthma and allergic disease has increased in many countries. It has been proposed that vaccinations may contribute to the development of allergic disease by reducing clinical infections in infancy or through the direct IgE-inducing effects of the vaccines. Evidence for a potential role of immunizations in the development of allergic disease is scarce. Therefore the objective was to study the associations between vaccinations against measles, mumps and rubella (MMR), natural infections of these diseases and atopic sensitization to indoor and outdoor allergens and allergic symptoms in schoolchildren. The cross-sectional study including 1537 8(th) grade school children aged 13-15 years living in 10 communities across Switzerland was organized in the framework of an environmental health surveillance program within the School Health Services (Swiss Surveillance Program of Childhood Asthma and Allergies with respect to Air Pollution and Climate, SCARPOL). Main outcome measures were asthma and sneezing during pollen season assessed by parental questionnaires and atopic sensitization determined by IgE concentrations to various allergens. It was found that parents' reported history of measles or mumps was associated with a stronger immune response than two or more vaccinations against the respective infection (measles: geometric mean IgG titers (GMT) lU/ml (95% Cl) 2.8 (2.0-3.9) vs. 1.2 (1.0-1.4), mumps: GMT PE/ml (95% Cl) 16.3 (13.9-19.1) vs. 8.5 (6.1-11.7). With respect to atopic sensitization similar associations for exposure by natural MMR-infections or MMR-vaccinations were found: measles: OR (95% Cl) 1.02 (0.53-1.96) vs. 1.22 (0.69-2.16), mumps: 0.59 (0.38-0.93) vs. 0.79 (0.49-1.27), rubella: 0.93 (0.61-1.43) vs. 0.95 (0.66-1.37), respectively. Inverse relationships were found between the risk of asthma and a positive disease history or vaccination of measles 0.36 (0.14-0.91) vs. 0.45 (0.21-0.98) or a positive serum titer against measles 0.65 (0.35-1.20). From the present study can be concluded that exposure by MMR-vaccinations or natural MMR-infections in childhood does not increase the risk of sensitization to common allergens as well as to allergic respiratory diseases. MMR-vaccinations or natural MMR-infections are therefore an unlikely factor contributing to the increase in atopic disease in developed countries.

Role of antibiotics and fungal microbiota in driving pulmonary allergic responses

Over the past four decades, there has been a significant increase in allergy and asthma in westernized countries, which correlates with alterations in fecal microbiota (microflora) and widespread use of antibiotics (the "hygiene hypothesis"). Antibiotics also lead to overgrowth of the yeast Candida albicans, which can secrete potent prostaglandin-like immune response modulators. We have developed a mouse model of antibiotic-induced microbiota disruption that includes stable increases in gastrointestinal (GI) enteric bacteria and GI Candida levels with no introduction of microbes into the lungs. Mice are treated for 5 days with cefoperazone in the drinking water, followed by a single oral gavage of C. albicans. This results in alterations of GI bacterial populations and increased yeast numbers in the GI microbiota for at least 2 to 3 weeks and can drive the development of a CD4 T-cell-mediated allergic airway response to subsequent mold spore (Aspergillus fumigatus) exposure in immunocompetent mice without previous systemic antigen priming. The allergic response in the lungs is characterized by increased levels of eosinophils, mast cells, interleukin-5 (IL-5), IL-13, gamma interferon, immunoglobulin E, and mucus-secreting cells. In the absence of antibiotics, mice exposed to Aspergillus spores do not develop an allergic response in the airways. This study provides the first experimental evidence to support a role for antibiotics and fungal microbiota in promoting the development of allergic airway disease. In addition, these studies also highlight the concept that events in distal mucosal sites such as the GI tract can play an important role in regulating immune responses in the lungs.

History of ear infections and prevalence of asthma in a national sample of children aged 2 to 11 years: the Third National Health and Nutrition Examination Survey, 1988 to 1994

METHODS

We analyzed data on 7,538 children aged 2 to 11 years who participated in the Third National Health and Nutrition Examination Survey to examine the cross-sectional associations of history of ear infections with prevalence of ever-diagnosed asthma and the prevalence of wheezing in the last year in US children.

RESULTS

History of ear infections was significantly related to the lifetime prevalence of diagnosed asthma (prevalence odds ratio [POR], 1.57; 95% confidence interval [CI], 1.05 to 2.36) and to the prevalence of wheezing in the last year (POR, 1.70; 95% CI, 1.22 to 2.37) after controlling for potential confounding variables. The number of ear infections was linearly and significantly related to the risk of asthma and wheezing in the last year. Among children with no diagnosis of asthma, there was a significant association between a history of ear infections and any wheezing in the last year (adjusted POR, 1.55; 95% CI, 1.07 to 2.25).

CONCLUSIONS

Our study indicated strong and significant associations of a history of asthma and wheezing with the frequency of ear infections in a nationally representative sample of 7,538 children aged 2 to 11 years. These findings highlight the need for prospective studies to examine further the relationship between asthma and ear infections.

Asthma and atopy - the price of affluence?

Irrespective of improved knowledge of many aspects of atopic diseases, the unfavorable trends in their prevalence particularly among children could not have been reversed. A growing body of evidence suggests that something may lack from our societal affluence that has the capacity to provide protection against the development of atopic diseases. Much attention during the last years has been devoted to the hygiene hypothesis. This review outlines the impact of environment and lifestyle, particularly from the perspective of the East-West gradient, on the development of atopic diseases, with a special emphasis on the hygiene hypothesis in its broadest sense.

Prevalence of skin diseases in Ibadan, Nigeria

AIM

To study the pattern of skin diseases in patients attending the skin clinic of the University College Hospital, Ibadan, Nigeria, and to compare our findings with studies performed earlier in the same clinic.

PATIENTS AND METHODS

The study involved 1091 new patients who had attended the skin clinic of the University College Hospital, Ibadan, Nigeria, between January 1994 and December 1998. The patients were examined by the authors, and laboratory investigations were ordered when necessary to make a diagnosis.

RESULTS

An increased prevalence of eczema, idiopathic pruritus, urticaria, connective tissue diseases, and fixed drug eruptions was observed. Infections, such as scabies, candidiasis, and tinea versicolor, had also increased. Pyoderma, leprosy, onchocerciasis, and dermatophytoses showed a decline. Psoriasis was uncommon, although there was a slight increase in prevalence. Vitiligo and alopecia were stable. Cutaneous tuberculosis, such as lupus vulgaris, was rare.

CONCLUSIONS

Allergic conditions have increased; connective tissue disorders, such as systemic lupus erythematosus, scleroderma, and discoid lupus erythematosus, have also increased. Cutaneous disorders associated with human immunodeficiency virus infection, such as seborrheic dermatitis, have increased. Health workers need to be educated on the management and treatment of these conditions, and should be advised to refer patients to appropriate health facilities when necessary.

Early-life exposure to antibacterials and the subsequent development of hayfever in childhood in the UK: case-control studies using the General Practice Research Database and the Doctors' Independent Network

BACKGROUND

Theoretically, antibacterial agents in early life might influence allergic sensitization in two ways: (i) as an indicator of infectious illness, they might be expected to protect against allergy; (ii) alternatively they might increase the risk through effects on the commensal bowel flora. Epidemiological evidence linking the prescription of antibacterial agents in early life to the subsequent development of hayfever is conflicting.

OBJECTIVE

To establish definitively whether an association exists between early-life antibacterial exposure and childhood hayfever diagnosis.

METHODS

Nested case-control studies were based on birth cohorts of children identified within two large UK general practice databases of electronic patient records. One hundred and sixteen thousand and four hundred and ninety-three children from 605 general practices were identified as being continuously registered from birth to at least age 5 years. Seven thousand and ninety-eight cases were diagnosed with hayfever after the age of 2 years. One control per case was matched for practice, birth month, sex and still being registered on case diagnosis date. Odds ratios were derived from conditional logistic regressions within each database followed by pooling using a fixed-effect model.

RESULTS

The pooled odds ratio for hayfever was 1.11, 95% CI (1.03-1.20) if exposed to antibacterials in the first year of life, 1.35 (1.25-1.46) in year 2 and 1.47 (1.37-1.59) in year 3. Adjusting for consultation frequency reduced these odds ratios to 0.92, 1.05 and 1.10, respectively. There was no evidence that broader spectrum antibacterials, exposure in any specific month of year 1 or in the grass pollen season influenced the risk of hayfever.

CONCLUSION

These data exclude any important effect of antibacterial exposure in infancy on subsequent hayfever risk. Associations reported in earlier studies have likely been exaggerated through publication bias and by lack of control for the tendency of some families to consult frequently for a range of conditions.

CD8+ T cells and immunoregulatory networks in asthma

It is well established that infection with respiratory viruses can cause acute local inflammation in humans and is a leading cause in the hospitalization of asthmatics. Less well recognized is the potential for viral infections to actually protect against the development of asthma, as are the cellular mechanisms which might underlie such protection. This review outlines the basic immunological pathways involved in atopic asthma and details the currently recognized cellular mechanisms induced by respiratory viral infections which can protect against the development of asthma. Specifically, it appears that virus infection induced memory T cells that remain in tissues, e.g. the lung and airways, can under certain circumstances create a local cytokine milieu which inhibits the development of ensuing allergic immune responses at that site. One key aspect of this immune modulation is the cytokine-dependent communication which occurs between the innate and the adaptive immune systems. The mechanistic principles underlying this form of immunomodulation should be taken into consideration when developing future forms of therapy and rational vaccine design.

An update on asthma management

Asthma remains a major cause of morbidity in the Australian community, despite enhanced strategies and interventions for achieving optimal outcomes. Although there is some evidence of over use of high doses of inhaled corticosteroids (ICS), there is also evidence for under use of ICS, despite long-term data demonstrating clear benefits of low doses. The present paper briefly discusses some of the issues that are pertinent to the development of sensitization and atopic disease, but focuses mainly on the current understanding of best clinical practice for adults with asthma and the optimal approach to management. A clear definition of asthma control and a systematic approach to down-titration to minimize ICS doses is crucial to achieving better outcomes. Patient self-management education and optimal therapy are the keys to achieving better outcomes, although uncertainty remains about recommendations for mild asthma, despite new data.

Caesarean section increases the risk of hospital care in childhood for asthma and gastroenteritis

OBJECTIVE

To investigate if caesarean section (CS) increases the risk for childhood asthma and gastroenteritis with reference made to children born with vaginal delivery (VD).

METHODS

Retrospective study of data from linked Swedish medical service registers--Medical Birth Registry (MBR) and Hospital Discharge Registry (HDR). Data were obtained from women without any background/perinatal morbidity noted, and from children without any neonatal complications. Children that had reached at least 1 year of age and were found in the HDR were considered as cases, whereas children not found in the HDR or hospitalized for other causes than asthma or gastroenteritis were defined as controls. Odds ratios (OR) stratified for year of birth, maternal age, parity and smoking in early pregnancy were calculated. Investigations were made comparing the risk for in hospital treatment for asthma or gastroenteritis in CS children and in VD siblings of CS children. The overall inpatient morbidity in CS and VD children were also investigated.

RESULTS

The OR for asthma in CS children was 1.31 [95% confidence interval (CI) 1.23-1.40]. The same OR, 1.31, was found for gastroenteritis (95% CI 1.24-1.38). The OR for CS children having experienced both asthma and gastroenteritis was further increased (1.74, 95% CI 1.36-2.23). The risk for asthma in VD siblings of CS children was not significantly increased, whereas VD siblings experienced a slightly increased risk for gastroenteritis. CS children had an increased overall in hospital morbidity when compared to VD children.

CONCLUSION

There is a significant increase of the risk for developing symptoms of asthma and/or gastroenteritis that motivates admission for hospital care in CS children older than 1 year. It is speculated that a disturbed intestinal colonization pattern in CS children may be a common pathogenic factor.

Inhibition of allergic disorders by infection with bacteria or the exposure to bacterial products

The incidence, severity, and mortality rate of allergic diseases, such as asthma, atopic dermatitis and rhinitis is increasing in the developed nations of the world, despite the use of steroids and other drugs. The reason for this development is unknown, but has been speculated to be due to a steady decline in infectious diseases. This view is supported by recent epidemiological and experimental findings showing that bacterial infections have the capacity to inhibit the development of allergic disorders. In addition, the exposure to bacterial products such as lipopolysaccharide (LPS) or bacterial DNA is also associated with a decrease in allergen-specific Th2 responses. Although the immunological mechanisms responsible for these protective effects are ill defined, recent publications indicate that they are associated with the induction of Th1 or T regulatory responses. This review focuses on experimental and epidemiological studies addressing the question if bacterial infections or the exposure to bacterial products can inhibit the development of allergic responses.

Is the hygiene hypothesis an example of hormesis?

The "hygiene hypothesis" has been suggested to explain the rising incidence of allergic disorders in developed countries. The postulated mechanism is that infectious and/or microbial agents stimulate the immune system toward Th1 (allergy fighting) rather than Th2 (allergy promoting) response. This paper reviews the evidence related to early life infectious/microbial exposures and subsequent atopic disorders and evaluates whether these data suggest a hormetic effect. Our review indicates an insufficient and contradictory association for bacterial/viral infections, with protective effects being either absent or specific to certain infections and/or populations. Chronic, heavy parasitic burdens appear to confer protection against atopic disorders, but are associated with considerable pathology. Moreover, light parasitic burden may increase allergic responses (i.e., no "low dose" beneficial effect). In contrast, there is consistent evidence that general microbial exposures, particularly gut commensals, may be protective against allergy development, which is consistent with a hormetic effect (i.e., potentially beneficial effects at low doses and detrimental effects at high levels).

CONCLUSION

General microbial exposures in relation to the "hygiene hypothesis" may represent a hormetic effect, although further research with more rigorous study methods (i.e., prospective designs and measurement of exposure timing, dose, route, etc.) are needed.

Prescriptions of systemic antibiotics for children in Germany aged between 0 and 6 years

Limited information is available about systemic antibiotic use among children in Germany. We therefore assessed prescription patterns by office-based physicians to analyse antibiotic consumption in early childhood. A total of 331 children < 6 years were eligible for inclusion. The number of antibiotic prescriptions, consumed daily doses, number of treatment courses, types of antibiotics and diagnoses for prescribing were determined. The prevalence of systemic antibiotic treatment was 42.9%. Antibiotic consumption was highest between 2 and 3 years of age (55.8%). The percentage of children receiving one, two or three courses of antibiotic treatment was 49.3, 28.2 and 16.2%, respectively. Acute otitis media (32.2%), upper respiratory tract infections (18.9%), tonsillitis (15.9%) and acute bronchitis (15.4%) were principal indications for treatment. Macrolides were most frequently prescribed (48.1%), followed by penicillin V (21.3%), broad-spectrum penicillins (14.3%), sulfonamides (10.5%) and cephalosporins (5.8%). Antibiotics not recommended for particular indication were selected in 5-43% of cases. The considerable prescription of systemic antibiotics to children in many European countries is also the case in Germany. A noteworthy trend emerged for suboptimal prescribing with second-line antibiotics. As such treatment may be associated with the development of bacterial resistance, improved guidelines for antibiotic treatment should be drawn up and enforced.

Role of intestinal flora in the development of allergy

PURPOSE OF REVIEW

The frequency of allergic diseases is increasing worldwide. Experimental and clinical studies have linked a reduced number of early infections to this trend. The gastrointestinal system, which comprises the largest lymphoid tissue and microbial reservoir of the body, has received more attention during the last few years as a potential determiner in the development of atopic disease.

RECENT FINDINGS

Alterations in intestinal microbiota have been detected both in infants suffering from allergic disease and in those later developing the disorder. Delay in the compositional development of and in gut microflora was a general finding in allergic children. In a subsequent study, perinatal administration of lactobacilli halved the later development of atopic eczema during the first 2 years of life. Specific strains of the healthy gut microbiota have been shown to induce the production of IL-10 and transforming growth factor-beta, which possess an important regulative role in the development of allergic type immune response. Probiotics also strengthen gut defence barrier mechanisms and reduce antigen load in the gut. Pattern recognition receptors in intestinal epithelial and antigen-presenting cells have been demonstrated to mediate a continuing dialogue between host and gut microbiota.

SUMMARY

Despite several promising findings, the exact role of gut normal microbiota in the development of allergy remains to be elucidated. For successful interventions, more data concerning a communication between host and specific microbial species are needed.

Relationship between group A beta-hemolytic streptococcal tonsillopharyngitis and asthma

Increasing morbidity due to asthma in children and antimicrobial resistance among human pathogens are both major public-health concerns. Frequent use of antibiotics during childhood might be a factor underlying the rising severity and prevalence of asthma and other allergic disorders. The objective of the study was to determine if pediatric patients with asthma or allergic rhinitis have an altered rate of group A beta hemolytic streptococcal (GABHS) tonsillopharyngeal infection which might support any change in guidelines for antibiotic prescription. A prospective analysis of all patients presenting a clinical feature of GABHS pharyngitis with a sore throat in two pediatric clinics located in Detroit, MI, USA and San Antonio de Areco, Buenos Aires, Argentina. Eligible patients aged between 2 and 18 years were screened for the presence of asthma and/or allergic rhinitis and administered a test (rapid strep test) and throat culture to determine GABHS infection. At the Redford Medical Center, Detroit, 500 patients met the eligibility criteria, with 168 (33.6%) having a positive strep test. At the San Antonio de Areco's Hospital, in a rural area 100 km away from Buenos Aires, 188 patients met the eligibility criteria, with 41 (21.8%) having a positive strep test or GABHS throat cultures. In both the Detroit [odds ratio (OR) = 1.36; 95% confidence interval (CI) 0.72-2.57] and Buenos Aires clinics (OR = 0.50; 95% CI 0.23-1.07), patients with asthma or allergic rhinitis were not at an increased risk for true GABHS tonsillopharyngeal infections when compared with the general pediatric population. These results suggest that children with asthma do not differ from the normal population in their risk of developing GABHS tonsillopharyngeal infection and should not be liberally prescribed antibiotics.

Asthma: environmental and occupational factors

Asthma is in several ways a difficult disease to study. Generally arising in childhood, its pattern is often one of remission and relapse; at any point there are difficulties in translating its characteristic, clinical features into an operational definition. Geographical and temporal patterns in its distribution - whereby the disease appears to have increased in frequency in more 'westernised' countries -suggest strong environmental determinants in its causation although there are, too, undoubted and important genetic influences on both its incidence and presentation. Recent aetiological research has concentrated on the function of allergen exposure or on the role of early-life microbial contact that may regulate the development of a range of childhood allergies, including asthma. To date the 'hygiene hypothesis' offers the most efficient explanation for the distribution of the disease in time and place although convincing evidence for it remains elusive.

The rise of atopy and links to infection

Atopy is the state of allergy to common environmental antigens. Genetic and environmental factors promote the disorder. The impressive rise in prevalence, mainly centred on socio-economically developed communities around the world, emphasizes the potent action of environmental factors in moulding this immune disorder which is characterized by inadequately restrained Th-2 immune mechanisms and IgE production. Reversing the epidemiological trend depends on our identifying the major environmental inputs and acting against these. As yet, the nature of these environmental factors remains to be clarified. Candidate factors include changes in diet, chemical air pollution and microbial exposures in developed countries. This article limits its scope to changing microbial exposures as a potential mechanism. (a) It records epidemiological data that have associated atopic status with less natural exposure to pathogens, parasites and commensal micro-organisms, but with more exposure to certain antibiotics and public health immunizations in early life. (b) It records studies in mice that support the concept that certain microbial exposures can inhibit experimental allergy. (c) It considers potential immune mechanisms for such an action, including the possibility that certain natural infections promote immune regulatory processes that can restrain atopy. It is concluded that the hypothesis that changing patterns of microbial exposure may have promoted the rise in atopy is viable, and that exciting possibilities for reversing the rise of atopy may be derived from further studies.

Farm residence and exposures and the risk of allergic diseases in New Zealand children

BACKGROUND

Studies in Europe have reported a reduced prevalence of allergy in farmers' children. We aimed to determine if there is a similar reduction in allergy among New Zealand farm children.

METHODS

Two hundred and ninety-three children participated (60%) aged 7-10 years, from selected schools in small towns and the surrounding rural area. Skin prick tests (SPT) to eight common allergens were performed. Parents completed questionnaires about allergic and infectious diseases, place of residence, exposure to animals, and diet, and they provided dust from the living-room floor. Endotoxin was measured using an Limulus amoebocyte lysate (LAL) assay and Der p 1 using enzyme-linked immunoassay (ELISA).

RESULTS

Current farm abode was found to increase the risk of having symptoms associated with allergy, but not SPT positivity. Independent inverse associations were found for early-life exposures: at least weekly consumption of yoghurt with hayfever (odds ratio (OR) = 0.3, 95% confidence intervals (CI) 0.1-0.7) and allergic rhinitis (OR = 0.3, 95% CI 0.2-0.7); any unpasteurized milk consumption with atopic eczema/dermatitis syndrome (AEDS) (OR = 0.2, 95% CI 0.1-0.8); cats inside or outside with hayfever (OR = 0.4, 95% CI 0.1-1.0) and AEDS (OR = 0.4, 95% CI 0.2-0.8); dogs inside or outside with asthma (OR = 0.4, 95% CI 0.2-0.8); and pigs with SPT positivity (OR = 0.2, 95% CI 0.1-0.9).

CONCLUSIONS

Despite finding a protective effect of early-life animal exposures, we found a greater prevalence of allergic disease on farms.

Respiratory symptoms and asthma in relation to cold climate, inhaled allergens, and irritants: a comparison between northern and southern Finland

We have compared data from northern and southern Finland in a large epidemiological survey on respiratory conditions. The aim was to compare the prevalence of respiratory symptoms, asthma, and chronic bronchitis in northern and southern Finland. The study was a part of comparative studies in Finland, Estonia, and Sweden, the FinEsS studies. Data from a postal survey on subjects aged 20-69 was analyzed. Participation rate was 84% of 7937 invited in Lapland in the north, and 77% of 7877 in Helsinki in the south. Physician-diagnosed asthma was reported by 5.6% in Helsinki, and by 5.5% in Lapland. Symptoms common in asthma were also equally prevalent in the two areas. Hay fever was significantly more common in Helsinki, 36% vs. 26% (p < 0.001). The prevalence for physician-diagnosed chronic bronchitis was not significantly higher in Helsinki (3.4%) than in Lapland (2.9%). Those working outdoors reported more bronchitic symptoms than people working indoors (p < 0.05). Respiratory symptoms provoked by pollen or animal dander were more common in Helsinki, while symptoms provoked by inhaled irritants or cold weather conditions were more prevalent in Lapland. Current smoking was equally prevalent: 37% in Lapland and 38% in Helsinki. Risk factor analysis showed an elevated risk for chronic productive cough for living in Helsinki (OR 1.32), however, increasing age and current smoking were the strongest risk factors. In conclusion, prevalence of asthma and asthma-related symptoms was similar in southern and northern Finland, but chronic bronchitis and bronchitic symptoms were more common in Helsinki, and the highest prevalence was found among current smokers working outdoors. Respiratory symptoms in cold weather were more prevalent in the north, while hay fever and respiratory symptoms provoked by allergens were more common in the south. The results support the view that environmental factors have a substantial effect on respiratory symptoms, but less effect on the prevalence of asthma.

Toll-like receptors as potential therapeutic targets for multiple diseases

The family of Toll-like receptors (TLRs) is receiving considerable attention as potential regulators and controllers of the immune response through their ability to recognize pathogen-associated molecular patterns. The discovery that endogenous ligands, as well as microbial components, are recognized by TLRs, and that small-molecular-mass synthetic compounds activate TLRs, raised interest in these receptors as potential targets for the development of new therapies for multiple diseases. In this review, we discuss the current and future use of TLR agonists or antagonists in chronic inflammatory diseases and highlight potential problems that are associated with such approaches.

Long-term protective and antigen-specific effect of heat-killed Mycobacterium vaccae in a murine model of allergic pulmonary inflammation

This report examines the effect of heat-killed Mycobacterium vaccae in a mouse model of allergic pulmonary inflammation. The s.c. administration of M. vaccae 3 wk before the immunization significantly reduced Ag-induced airway hyperreactivity and the increase in the numbers of eosinophils observed in the bronchoalveolar lavage fluid, blood, and bone marrow, even though no detectable changes in either cytokine (IL-4, IL-13, IL-5, and IFN-gamma) or total IgE levels were observed. Furthermore, transfer of splenocytes from OVA-immunized and M. vaccae-treated mice into recipient, OVA-immunized mice significantly reduced the allergen-induced eosinophilia by an IFN-gamma-independent mechanism, clearly indicating that the mechanism by which M. vaccae induces its inhibitory effect is not due to a redirection from a predominantly Th2 to a Th1-dominated immune response. The protective effect of M. vaccae on the allergen-induced eosinophilia lasted for at least 12 wk after its administration, and the treatment was also effective in presensitized mice. Moreover, the allergen specificity of the inhibitory effect could be demonstrated using a double-immunization protocol, where M. vaccae treatment before OVA immunization had no effect on the eosinophilic inflammation induced by later immunization and challenge with cockroach extract Ag. Taken together, these results clearly demonstrate that M. vaccae is effective in blocking allergic inflammation by a mechanism independent of IFN-gamma, induces long term and Ag-specific protection, and therefore has both prophylactic and therapeutic potential for the treatment of allergic diseases.

Lack of association between antibiotic use in the first year of life and asthma, allergic rhinitis, or eczema at age 5 years

Five retrospective studies have reported an association between antibiotic use in early life and asthma in childhood. We studied the relationship between the use of oral antibiotics in the first year of life and asthma, allergic rhinitis, and eczema at age 5 years among 448 children with a parental history of atopy monitored from birth. After adjustment for potential confounders, we found no significant association between antibiotic use in the first year of life and asthma (odds ratio [OR] for one versus no courses of antibiotics, 0.5; 95% confidence interval [CI] for OR, 0.2 to 1.5; OR for two or more versus no courses of antibiotics, 1.0; 95% CI for OR, 0.5 to 2.2), recurrent wheezing, allergic rhinitis, or eczema at age 5 years. There was no significant association between antibiotic use in the first year of life and having at least one of three atopic diseases (asthma, allergic rhinitis, or eczema) at age 5 years (OR for one versus no courses of antibiotics, 0.7; 95% CI, 0.4 to 1.4; OR for two or more versus no courses of antibiotics, 0.9; 95% CI, 0.5 to 1.4). Our findings do not support the hypothesis that antibiotic use in early life is associated with the subsequent development of asthma and atopy in childhood.

Maternal vaginal microflora during pregnancy and the risk of asthma hospitalization and use of antiasthma medication in early childhood

BACKGROUND

Infants with wheezing and allergic diseases have a microflora that differs from that of healthy infants. The fetus acquires microorganisms during birth when exposed to the maternal vaginal microflora. It is therefore conceivable that the maternal vaginal microflora might influence the establishment of the infant flora and, as a consequence, the development of wheezing and allergic diseases.

OBJECTIVE

We sought to study the associations between the composition of the maternal vaginal microflora and the development of wheezing and asthma in childhood.

METHODS

We performed a population-based cohort study in Denmark. Vaginal samples for bacterial analysis were obtained during pregnancy. A total of 2927 women (80% of the invited women) completed the study and had 3003 live infants. Infant wheezing was assessed as one or more hospitalizations for asthma between 0 and 3 years of age. Asthma was assessed as use of 3 or more packages of antiasthma medication between 4 and 5 years of age.

RESULTS

Maternal vaginal colonization with Ureaplasma urealyticum during pregnancy was associated with infant wheezing (odds ratio [OR], 2.0; 95% CI, 1.2-3.6), but not with asthma, during the fifth year of life. Maternal colonization with staphylococci (OR, 2.2; 95% CI, 1.4-3.4) and use of antibiotics in pregnancy (OR, 1.7; 95% CI, 1.1-2.6) were associated with asthma during the fifth year of life.

CONCLUSION

The composition of the maternal vaginal micro-flora might be associated with wheezing and asthma in the offspring up to 5 years of age.

An oral introduction of intestinal bacteria prevents the development of a long-term Th2-skewed immunological memory induced by neonatal antibiotic treatment in mice

BACKGROUND

Recent epidemiological studies indicate that antibiotic use in infancy may be associated with an increased risk of developing atopy. Our previous work on animals demonstrated that kanamycin use during infancy promotes a shift in the Th1/Th2 balance towards a Th2-dominant immunity.

OBJECTIVE

The first purpose of this study is to clarify whether or not the supplementation of intestinal bacteria can reverse such a Th2-skewed response induced by neonatal antibiotic use. The second objective is to elucidate the contribution of genetic factors to antibiotic-induced immune-deviation.

METHODS

BALB/c or C57BL/6 mice at 3 weeks of age were orally administered 600 microg/day of kanamycin sulphate for seven consecutive days. Thereafter, the mice were inoculated with one type of intestinal bacterial species: Enterococcus faecalis, Lactobacillus acidophilus or Bacteroides vulgatus. Blood samples were collected 10 weeks after the cessation of kanamycin treatment, and the effect of the kanamycin treatment on Th1/Th2 balance was evaluated based on in vivo antibody levels.

RESULTS

A kanamycin-induced elevation of the serum IgE levels was reversed by the supplementation with Enterococcus faecalis, and to a lesser extent by that with Lactobacillus acidophilus. The IgE/IgG2a ratio in the mice supplemented with Enterococcus faecalis significantly decreased in comparison with that in the kanamycin-treated mice without any bacterial supplementation, while such a ratio was enhanced in the mice inoculated with Bacteroides vulgatus. No antibiotic-induced Th2-skewed response was seen in C57BL/6 mice that are genetically biased towards Th1-dominant immunity.

CONCLUSION

These results suggest that adequate probiotic intervention after antibiotic treatment may improve the intestinal ecosystem, and thereby prevent the Th2-shifted immunity induced by neonatal antibiotic use. In addition, the difference of genetic backgrounds also contributes to such an antibiotic-induced Th2-skewed response.

Asthma management: Part 1: An overview of the problem and current trends

Death rates from asthma have increased or remained stable over the past decade despite increased knowledge about the pathophysiology and improved treatment of the disease, a fact that is both puzzling and disconcerting. Some children with asthma experience severe and life-interfering exacerbations separated by long periods of normal lung function and no symptoms. Asthma management plans are developed by primary care providers and the family. School nurses implement and monitor the child's response to the plan. Therefore, the school nurse needs current information about asthma management. Part I of this two-part series describes the pathophysiology of asthma and the types, risk factors, and current trends in management of the disease. The role of the school nurse in asthma management is outlined, including how he or she can influence environmental factors that precipitate asthma symptoms or exacerbations. Part II will discuss the role of the school nurse in pharmacologic management of asthma. Complementary alternative medicine for asthma management will be described, as well as health teaching for the child with asthma and their family.

Respiratory and allergic diseases: from upper respiratory tract infections to asthma

Patients with asthma and allergic rhinitis may benefit from hydration and a diet low in sodium, omega-6 fatty acids, and transfatty acids, but high in omega-3 fatty acids (i.e., fish, almonds, walnuts, pumpkin, and flax seeds), onions, and fruits and vegetables (at least five servings a day). Physicians may need to be more cautious when prescribing antibiotics to children in their first year of life when they are born to families with a history of atopy. More research is needed to establish whether supplementation with probiotics (lactobacillus and bifidobacterium) during the first year of life or after antibiotic use decreases the risk of developing asthma and allergic rhinitis. Despite a theoretic basis for the use of vitamin C supplements in asthmatic patients, the evidence is still equivocal, and long-term studies are needed. The evidence is stronger for exercise-induced asthma, in which the use of vitamin C supplementation at a dosage of 1 to 2 g per day may be helpful. It is also possible that fish oil supplements, administered in a dosage of 1 to 1.2 g of EPA and DHA per day, also may be helpful to some patients with asthma. Long-term studies of fish oil and vitamin C are needed for more definite answers. For the patient interested in incorporating nutritional approaches, vitamin C and fish oils have a safe profile. However, aspirin-sensitive individuals should avoid fish oils, and red blood cell magnesium levels may help in making the decision whether to use additional magnesium supplements. Combination herbal formulas should be used in the treatment of asthma with medical supervision and in collaboration with an experienced herbalist or practitioner of TCM. Safe herbs, such as Boswellia and gingko, may be used singly as adjuncts to a comprehensive plan of care if the patient and practitioner have an interest in trying them while staying alert for drug-herb interactions. No data on the long-term use of these single herbs in asthma exist. For the motivated patient, mind-body interventions such as yoga, hypnosis, and biofeedback-assisted relaxation and breathing exercises are beneficial for stress reduction in general and may be helpful in further controlling asthma. Encouraging parents to learn how to massage their asthmatic children may appeal to some parents and provide benefits for parents and children alike. Acupuncture and chiropractic treatment cannot be recommended at this time, although some patients may derive benefit because of the placebo effect. For patients with allergic rhinitis, there are no good clinical research data on the use of quercetin and vitamin C. Similarly, freeze-dried stinging nettle leaves may be tried, but the applicable research evidence also is poor. Further studies are needed to assess the efficacy of these supplements and herbs. Homeopathic remedies based on extreme dilutions of the allergen may be beneficial in allergic rhinitis but require collaboration with an experienced homeopath. There are no research data on constitutional homeopathic approaches to asthma and allergic rhinitis. Patients with COPD are helped by exercise, pulmonary rehabilitation, and increased caloric protein and fat intake. Vitamin C and n-3 supplements are safe and reasonable; however, studies are needed to establish their efficacy in COPD. On the other hand, there are convincing data in favor of N-acetyl-cysteine supplementation for the patient with COPD at doses ranging between 400 and 1200 mg daily. Red blood cell magnesium levels may guide the use of magnesium replacement. The use of L-carnitine and coenzyme Q10 in patients with COPD needs further study. The addition of essential oils to the dietary regimen of patients with chronic bronchitis is worth exploring. Patients with upper respiratory tract infections can expect a shorter duration of symptoms by taking high doses of vitamin C (2 g) with zinc supplements, preferably the nasal zinc gel, at the onset of their symptoms. Adding an herb such as echinacea or Andrographis shortens the duration of the common cold. The one study on Elderberry's use for the flu was encouraging, and the data on the homeopathic remedy Oscillococcinum interesting, but more studies should be performed. Saline washes may be helpful to patients with allergic rhinitis and chronic sinusitis. Patients also may try the German combination (available in the United States) of elderberry, vervain, gentian, primrose, and sorrel that has been tested in randomized clinical trials. Bromelain is safe to try; the trials of bromelain supplementation were promising but were never repeated. The preceding suggestions need to be grounded in a program based on optimal medical management. Patients need to be well educated in the proper medical management of their disease and skilled at monitoring disease stability and progress. Asthmatic patients need to monitor their bronchodilator usage and peak flow meter measurements to step up their medical treatment in a timely manner, if needed. Patients welcome physician guidance when exploring the breadth of treatments available today. A true patient-physician partnership is always empowering to patients who are serious about regaining their function and health.

Reduced soluble CD14 levels in amniotic fluid and breast milk are associated with the subsequent development of atopy, eczema, or both

BACKGROUND

Exposure to various microbial products in early life reduces the risk of atopy. Such exposure induces downregulation of T(H)2 allergy-biased responses by means of pattern recognition molecules, such as CD14, an LPS receptor.

OBJECTIVE

We sought to determine whether infant and maternal levels of soluble CD14 (sCD14) are associated with the atopic outcomes of infants.

METHODS

Levels of sCD14 in plasma, amniotic fluid, and breast milk were measured with a specific ELISA in different cohorts. Expression of toll-like receptors in the fetal gut was examined by using RT-PCR.

RESULTS

Soluble CD14 levels increased during fetal development and postnatally, attaining adult levels by around 4 months of age, with an overshoot of adult levels from 6 months of age. There was no difference in plasma sCD14 levels at birth of children with a high compared with those with a low risk of development of atopy. Amniotic fluid sCD14 levels at midgestation (16-17 weeks) were significantly lower when the child was subsequently atopic (P <.05). Soluble CD14 levels in breast milk collected 3 months postpartum were significantly lower in children with eczema at 6 months of age, irrespective of whether they were atopic (P =.003). Transcripts for toll-like receptor 4, which would enable transmembrane signaling for LPS/sCD14 complexes, were expressed within fetal gut and skin.

CONCLUSION

Exposure to reduced levels of sCD14 in the fetal and neonatal gastrointestinal tract is associated with the development of atopy, eczema, or both. Thus the exogenous supply of sCD14 might influence immunologic reactivity both locally and systemically in early life and thereby influence disease outcome.

Critical evaluation of prognostic factors in childhood asthma

Current knowledge of the natural history of asthma is improving through the establishment of a more precise definition of asthma linked with information from a number of large-scale longitudinal studies. Risk factors for the development of childhood asthma are now more clearly understood. They include gender, atopic status, genetic and familial factors, respiratory infections, and outdoor and indoor pollution (1). In the present review two types of asthma and their prognosis will be discussed: (1) Asthma in preschool children and its risk factors for evolution towards persistent childhood asthma. (2) Asthma in older children and its risk factors for evolution towards adult asthma.

Does a higher number of siblings protect against the development of allergy and asthma? A review

STUDY OBJECTIVE

To review the "protective" effects of having a higher number of siblings for the risk of atopic eczema, asthma wheezing, hay fever, and allergic sensitisation.

METHOD

Review of the literature (Medline since 1965 and references).

MAIN RESULTS

53 different studies were identified. For eczema, 9 of 11 studies reported an inverse relation with number of siblings; for asthma and wheezing, 21 of 31 reported the inverse association; for hay fever, all 17 studies showed the effect; for allergic sensitisation or immunoglobulin E reactivity 14 of 16 studies supported the "protective" effect of a higher number of siblings. The studies emphasise a "theory" that is based exclusively on epidemiological associations.

CONCLUSIONS

Research has not yet answered the question of which causal factors explain the sibling effect. Causal factors must meet two criteria; they must vary with sibship size and they must protect against atopic manifestations. The prevailing "hygiene hypothesis" failed to explain the findings adequately. Alternative explanations include in utero programming or endocrine explanatory models. The epidemiology research into siblings and atopic disorders has entered an intellectually challenging phase. Possessing sufficient knowledge about the causal factors might prevent at least 30% of all cases of asthma, eczema, and hay fever.

What is the evidence for a causal link between hygiene and infections?

Even in an era in which access to personal "cleanliness" and a public health infrastructure are readily available in developed countries, illnesses associated with day care centres and homes continue to be a problem. The inhabitants of less developed countries, on the other hand, must contend with an inadequate public health infrastructure, lack of education programmes, and economic limitations in obtaining hygiene products. Therefore, less developed countries carry a greater burden of morbidity and mortality from infectious illnesses. The objective of this review is to examine and assess the epidemiological evidence for a causal relation between hygiene practices and infections. The Medline database was searched from January 1980 to June 2001 and studies were included if the outcome(s) was infection or symptoms of infection, and if the independent variable(s) was one or more hygiene measures. The strength of the association as measured by the relative reduction in risk of illness was appreciable and generally greater than 20%. Despite methodological strengths and limitations of the studies assessed, the weight of evidence collectively suggests that personal and environmental hygiene reduces the spread of infection. The results from this review demonstrate that there is a continued, measurable, positive effect of personal and community hygiene on infections.

Penicillin conjugates to interferon-gamma and reduces its activity: a novel drug-cytokine interaction

Beta-lactam antibiotics are the class of drug most frequently associated with IgE-mediated allergy but the mechanisms underlying this response are poorly understood. IFN-gamma is a key cytokine in immunity with regulatory actions on monocytes, NK cells, epithelial cells, and T and B lymphocytes. IFN-gamma promotes Th1 responses and inhibits Th2- and IgE-mediated responses. In this study we show, by Western blotting, that the prototype beta-lactam benzylpenicillin (BP) conjugates to human IFN-gamma but not to IL-4. The interaction of BP with IFN-gamma inhibited the cytokine's detection by immunoassay and impaired its activity, as assessed in three different assays: upregulation of MHC molecules on monocytes plus induction of nitric oxide synthesis and expression of monocyte chemoattractant protein-1 mRNA by epithelial cells. This is the first reported example of a direct drug-cytokine interaction and suggests a mechanism by which penicillin may disrupt IFN-gamma-dependent immune responses and promote allergy.

The germless theory of allergic disease: revisiting the hygiene hypothesis

Rising rates of allergic disease accompany the healthier benefits of a contemporary westernized lifestyle, such as low infant mortality. It is likely that these twinned phenomena are causally related. The hygiene hypothesis states that allergy and increased longevity are both consequences of reducing infectious stressors during early childhood for millennia. Mechanistic explanations for the hygiene hypothesis have typically invoked the T-helper-type 1/2 (T(H)1/T(H)2) model. Here, we discuss why we favour a broader 'counter-regulatory' model--one that might also explain the increasing incidence of autoimmune disease in westernized countries.

Parental smoking and respiratory tract infections in children

The adverse health consequences of exposing children to tobacco smoke have been well documented. Re-calculation of the data available from cohort and cross-sectional studies worldwide shows that between 500-2500 excess hospitalisations and between 1000 to 5000 excess diagnoses per 100 000 young children as result from respiratory infections can be directly attributed to parental smoking. Results of published meta-analyses support these figures, which are probably under-estimated because of the effects of non-differential misclassification bias. These excess infections are a source of preventable morbidity and have a high cost to the community. They also have important long-term consequences because children who have respiratory infections in early life are at an increased risk of developing asthma in later childhood. More effective strategies that prevent smoking in young people before they become parents have the potential to lead to reductions in these high rates of unnecessary morbidity in the next generation of children.