Soup Kettle Topics: Epidemiology– Hygiene Hypothesis and related issues

Title: Intradermal Administration of a Killed Mycobacterium Vaccae Suspension (Srl 172) Is Associated with Improvement in Atopic Dermatitis in Children with Moderate-to-Severe Disease
Author: Arkwright, P. D.; David, T. J.; (Date: Mar, 2001)
Journal: J Allergy Clin Immunol; V. 107; Issue: 3; Pages: 531-4

Abstract: BACKGROUND: Although a doubling in the prevalence of atopic disease, including atopic dermatitis, in the Western world over the last few generations has been paralleled by a marked reduction in infectious diseases, especially tuberculosis, it is unclear whether this increase in atopy is causally related to reduced exposure to mycobacteria. OBJECTIVES: The aim of this study was to determine whether administration of mycobacterial antigens to atopic individuals might ameliorate their disease. METHODS: Forty-one children aged 5 to 18 years with moderate-to-severe atopic dermatitis were enrolled in a randomized, double-blind, placebo-controlled trial, where they were given either one intradermal injection of killed Mycobacterium vaccae (SRL 172) or buffer solution (placebo). Changes in skin surface area affected by dermatitis and dermatitis severity score were assessed before treatment and at 1 and 3 months after treatment. RESULTS: Children treated with SRL 172 showed a mean 48% (95% CI, 32%-65%) reduction in surface area affected by dermatitis compared with a mean 4% (95% CI, -29% to 22%) reduction for the placebo group (P <.001) and a median 68% (interquartile range, 46%-85%) reduction in dermatitis severity score compared with 18% (interquartile range, -2% to 34%) for the placebo group (P <.01) at 3 months after treatment. There were no untoward effects of the treatment, apart from a local reaction in 13 of the 21 children, which occurred 1 month after SRL 172 administration and settled spontaneously. CONCLUSION: SRL 172 was associated with an improvement in the severity of the dermatitis in children with moderate-to-severe disease.
Notes: Clinical Trial
Journal Article
Randomized Controlled Trial
URL: http://www.mosby.com/scripts/om.dll/serve?action=searchDB&searchDBfor=art&artType=abs&id=a113081&target=
Author Address: Academic Unit of Child Health, University of Manchester, Booth Hall Children’s Hospital, Manchester, UK.


Title: Improvement in Psoriasis after Intradermal Administration of Heat-Killed Mycobacterium Vaccae
Author: Balagon, M. V.; Walsh, D. S.; Tan, P. L.; Cellona, R. V.; Abalos, R. M.; Tan, E. V.; Fajardo, T. T.; Watson, J. D.; Walsh, G. P.; (Date: Jan, 2000)
Journal: Int J Dermatol; V. 39; Issue: 1; Pages: 51-8

Abstract: BACKGROUND: New treatments for psoriasis are being developed, but many are associated with limited efficacy, side-effects, or rapid recurrence after discontinuation. Thus, the aim of new agents is to induce longer term remissions with fewer side-effects. Preliminary studies have shown that Mycobacterium vaccae, a nonpathogenic organism prepared as a heat-killed suspension, may induce periods of remission in some psoriasis patients when administered intradermally. METHODS: To further assess the efficacy and tolerability of M. vaccae in patients with moderate to severe psoriasis (psoriasis area and severity index (PASI) of 12-35), we conducted an open label study whereby 24 patients received two intradermal inoculations of M. vaccae in lesion-free deltoid skin, separated by a period of 3 weeks. RESULTS: Twelve weeks after starting treatment, 14 of 24 patients (58%) showed marked improvement in the PASI score (greater than 50% reduction), two had moderate improvement (25-50% reduction), six were unchanged (< 25% reduction), and two had worsened (> 5% increase). By 24 weeks, 11 of 22 patients continued to show greater than 50% improvement. Five patients had complete clearance of skin lesions that lasted for at least 6 months. CONCLUSIONS: Intradermal administration of heat-killed M. vaccae suspension was well tolerated and induced clinically significant improvement in a majority of psoriasis patients in this cohort. Placebo-controlled testing to further define the efficacy of this treatment is warranted.
Notes: Clinical Trial
Journal Article
Author Address: Leonard Wood Memorial Center for Leprosy Research (American Leprosy Foundation), Cebu City, Philippines.


Title: Does the Failure to Acquire Helminthic Parasites Predispose to Crohn’s Disease?
Author: Elliott, D. E.; Urban, Jf Jr; Argo, C. K.; Weinstock, J. V.; (Date: Sep, 2000)
Journal: Faseb J; V. 14; Issue: 12; Pages: 1848-55

Abstract: Two polarized patterns (Th1 and Th2) of cytokines regulate inflammatory responses. Each cytokine pattern inhibits production of the opposing pattern. Lymphocytes from inflamed intestine due to Crohn’s disease secrete a Th1 pattern of cytokines. Crohn’s disease is most prevalent in highly industrialized countries with temperate climates. It occurs rarely in tropical third world countries with poor sanitation. We propose that exposure to an environmental agent predisposes individuals to Crohn’s disease. Parasitic worms (helminths) are common in tropical climates and in populations subject to crowding and poor sanitation. Children are most subject to helminthic colonization. Many helminths live within or migrate through the human gut where they interact with the mucosal immune system. The host mounts a mucosal response that includes Th2 cytokine production limiting helminthic colonization. Helminths and their eggs probably are the most potent stimulators of mucosal Th2 responses. The Th2 response provoked by parasitic worms can modulate immune reactions to unrelated parasitic, bacterial, and viral infections. Many people in developed countries now live in increasingly hygienic environments, avoiding exposure to helminths. Perhaps failure to acquire these parasites and experience mucosal Th2 conditioning predisposes to Crohn’s disease, which is an overly active Th1 inflammation.
Notes: Journal Article
URL: http://www.fasebj.org/cgi/content/full/14/12/1848
http://www.fasebj.org/cgi/content/abstract/14/12/1848
Author Address: Department of Internal Medicine, Division of Gastroenterology/Hepatology, University of Iowa, Iowa City, Iowa 52242, USA.


Title: The Other Side of the Coin: The Protective Role of the Th2 Cytokines
Author: Finkelman, F. D.; Urban, J. F., Jr.; (Date: May, 2001)
Journal: J Allergy Clin Immunol; V. 107; Issue: 5; Pages: 772-80

Abstract: Although T(H)2 cytokine involvement in allergy makes these cytokines attractive therapeutic targets, they protect against ectoparasites and gastrointestinal worms and suppress inflammation induced by T(H)1 cytokines. T(H)2 cytokines induce mastocytosis, eosinophilia, IgE synthesis, and mucus production. Each element of this response protects against some worms; however, different worms are protected against by different elements of the total response. The induction of the entire response by most parasitic worms suggests that it is safer for the immune system to make a stereotyped worm-protective response than to attempt to match a more specific response to a particular worm. In contrast, the reciprocal antagonism between T(H)1 and T(H)2 cytokines suggests that it is safer for the immune system to limit immunopathology by suppressing inflammatory effector mechanisms not required for host protection against a particular pathogen class than to make an all-purpose inflammatory response. This, in turn, implies that innate immunity can distinguish different classes of parasites (eg, worms vs protozoa) but has limited ability to distinguish individual parasites within a class (eg, different worms). Although these considerations suggest that T(H)2 cytokine antagonists may increase the risk and severity of worm infections and T(H)1 cytokine-mediated inflammatory disorders, such therapy should be relatively safe if it is restricted to areas in which worm infections are rare and commonsense precautions are taken to minimize the risk of inducing T(H)1 cytokine-related inflammatory disease.
Notes: Journal Article
Review
Review, Tutorial
URL: http://www.mosby.com/scripts/om.dll/serve?action=searchDB&searchDBfor=art&artType=abs&id=a114989&target=
Author Address: University of Cincinnati College of Medicine, and the Cincinnati Veterans Administration Medical Center, Cincinnati, USA.


Title: Do Common Childhood Infections ‘Teach’ the Immune System Not to Be Allergic?
Author: Folkerts, G.; Walzl, G.; Openshaw, P. J.; (Date: Mar, 2000)
Journal: Immunol Today; V. 21; Issue: 3; Pages: 118-20

Notes: Congresses
Author Address: Dept of Pharmacology and Pathophysiology, Faculty of Pharmacy, Utrecht University, the Netherlands. G.Folkerts@pharm.uu.nl


Title: Microbial Stimulation as an Aetiologic Factor in Atopic Disease
Author: Holt, P. G.; Macaubas, C.; Prescott, S. L.; Sly, P. D.; 1999)
Journal: Allergy; V. 54 Suppl 49; Pages: 12-6

Abstract: Epidemiologic evidence from various sources suggests that exposure to microbial stimuli during early childhood can influence the induction and expression of atopic diseases, particularly in the respiratory tract. Moreover, these effects may have long-lasting consequences in relation to expression of the atopic phenotype in adulthood. This review discusses key aspects of this evidence in relation to the underlying mechanisms which regulate T-helper (Th)-cell function; in particular, the generation of Th-memory cells responsive to inhalant allergens.
Notes: Journal Article
Author Address: Division of Cell Biology, TVW Telethon Institute for Child Health Research, West Perth, Australia. patrick@ichr.uwa.edu.au


Title: Early Life Receipt of Antibiotics and Atopic Disorder
Author: Hopkin, J. M.; (Date: Jun, 1999)
Journal: Clin Exp Allergy; V. 29; Issue: 6; Pages: 733-4

Notes: Editorial
Review
Review, Tutorial


Title: Is Infant Immunization a Risk Factor for Childhood Asthma or Allergy?
Author: Kemp, T.; Pearce, N.; Fitzharris, P.; Crane, J.; Fergusson, D.; St George, I.; Wickens, K.; Beasley, R.; (Date: Nov, 1997)
Journal: Epidemiology; V. 8; Issue: 6; Pages: 678-80

Abstract: The Christchurch Health and Development Study comprises 1,265 children born in 1977. The 23 children who received no diphtheria/pertussis/tetanus (DPT) and polio immunizations had no recorded asthma episodes or consultations for asthma or other allergic illness before age 10 years; in the immunized children, 23.1% had asthma episodes, 22.5% asthma consultations, and 30.0% consultations for other allergic illness. Similar differences were observed at ages 5 and 16 years. These findings do not appear to be due to differential use of health services (although this possibility cannot be excluded) or con-founding by ethnicity, socioeconomic status, parental atopy, or parental smoking.
Notes: Journal Article
Author Address: Department of Medicine, Wellington School of Medicine, New Zealand.


Title: Cross Sectional Retrospective Study of Prevalence of Atopy among Italian Military Students with Antibodies against Hepatitis a Virus
Author: Matricardi, P. M.; Rosmini, F.; Ferrigno, L.; Nisini, R.; Rapicetta, M.; Chionne, P.; Stroffolini, T.; Pasquini, P.; D’Amelio, R.; (Date: Apr 5, 1997)
Journal: Bmj; V. 314; Issue: 7086; Pages: 999-1003

Abstract: OBJECTIVE: To investigate the working hypothesis that common infections occurring early in life prevent atopy. DESIGN: Cross sectional, retrospective study of young Italian men with results for hepatitis A serology and atopy. SETTING: Air force school of military students in Caserta, Italy. SUBJECTS: 1659 male students aged 17-24, most of whom (90%) were from central and southern Italy. MAIN OUTCOME MEASURES: Skin sensitisation and specific IgE antibodies to locally relevant airborne allergens; diagnosis of respiratory allergy (asthma or rhinitis, or both); hepatitis A seropositivity. RESULTS: 443 of the 1659 subjects (26.7%) were positive for hepatitis A virus antibody. Atopy was less common among seropositive than seronegative subjects according to skin sensitization (weal reaction > or = 3 mm) to one or more allergens (21.9% (97/443) v 30.2% (367/1216), P < 0.001); polysensitisation (sensitive to three or more allergens) (2.7% (12/443) v 6.4% (78/1216), P < 0.01); high specific IgF concentration (9.7% (43/443) v 18.4% (224/1216), P < 0.00005); and lifetime prevalence of allergic rhinitis or asthma, or both (8.4% (37/443) v 16.7% (203/1216), P < 0.001). Hepatitis A seropositivity remained inversely associated with atopy after adjusting for father’s education, the number of older siblings, and the area of residence (based on the number of inhabitants). The prevalence of atopy was constantly low among seropositive subjects, whatever the number of older siblings; by contrast, it increased with a decreasing number of older siblings among seronegative subjects. CONCLUSION: Indirect but important evidence is added to the working hypothesis as common infections acquired early in life because of the presence of many older siblings (among seronegative subjects) or because of unhygienic living conditions (among seropositive subjects) may have reduced the risk of developing atopy.
Notes: Journal Article
Author Address: Laboratorio di Immunologia cd Allergologia, Divisione Aerea, Studi Ricerche e Sperimentaziom, Pomezia (Roma), Italy. matricardi.pm@mclink.it


Title: Sibship Size, Birth Order, and Atopy in 11,371 Italian Young Men
Author: Matricardi, P. M.; Franzinelli, F.; Franco, A.; Caprio, G.; Murru, F.; Cioffi, D.; Ferrigno, L.; Palermo, A.; Ciccarelli, N.; Rosmini, F.; (Date: Apr, 1998)
Journal: J Allergy Clin Immunol; V. 101; Issue: 4 Pt 1; Pages: 439-44

Abstract: BACKGROUND: Having a low number of siblings and a low birth order has been reported to be a relevant risk factor for development of atopic diseases and skin sensitization to common inhalants. Although the inverse association of atopy with sibship size has been confirmed repeatedly, the association with birth order has provided conflicting results. This possibly is due to the relatively small size of the population sample examined. OBJECTIVE: The objective of this study was to investigate the relation between sibship size, birth order, and atopy in a very large population sample, highly homogeneous for age and sex. METHODS: This was a retrospective survey of 11,371 Italian young men, 18 to 24 years old, all candidates for enrollment in the Italian Air Force. Demographic data had been collected by a standard questionnaire. Specific IgE for locally relevant airborne allergens had been tested by a multi-RAST assay (CAP-Phadiatop). RESULTS: The prevalence of atopy (defined as a high level of specific IgE against inhalants [cut-point >1.2 log RU]) was inversely related to the total number of siblings (25% in those with no siblings and 9% in those with five or more siblings), with a mean of a 3% decrease in prevalence for each added sibling. This relation persisted after adjustment for relevant variables such as father’s education and rural and southern residence. An independent association between birth order and atopy was also observed because the decrease in atopy prevalence with increasing numbers of older siblings was significantly steeper than that found with the number of younger siblings (chi2 = 179, df = 1, p < 0.0001). CONCLUSIONS: In a very large and homogeneous population sample of a Mediterranean country, not only sibship size but also birth order was significantly associated with atopy. This observation further highlights the role of family structure in the development of atopy and supports the hypothesis that cross-infections acquired early in infancy or in later childhood might prevent development of atopy later in life.
Notes: Journal Article
Author Address: Lab. di Immunologia ed Allergologia, Divisione Aerea Studi Ricerche e Sperimentazioni, Pomezia, Rome, Italy.


Title: Exposure to Foodborne and Orofecal Microbes Versus Airborne Viruses in Relation to Atopy and Allergic Asthma: Epidemiological Study
Author: Matricardi, P. M.; Rosmini, F.; Riondino, S.; Fortini, M.; Ferrigno, L.; Rapicetta, M.; Bonini, S.; (Date: Feb 12, 2000)
Journal: Bmj; V. 320; Issue: 7232; Pages: 412-7

Abstract: OBJECTIVE: To investigate if markers of exposure to foodborne and orofecal microbes versus airborne viruses are associated with atopy and respiratory allergies. DESIGN: Retrospective case-control study. PARTICIPANTS: 240 atopic cases and 240 non-atopic controls from a population sample of 1659 participants, all Italian male cadets aged 17-24. SETTING: Air force school in Caserta, Italy. MAIN OUTCOME MEASURES: Serology for Toxoplasma gondii, Helicobacter pylori, hepatitis A virus, measles, mumps, rubella, chickenpox, cytomegalovirus, and herpes simplex virus type 1; skin sensitisation and IgE antibodies to relevant airborne allergens; total IgE concentration; and diagnosis of allergic asthma or rhinitis. RESULTS: Compared with controls there was a lower prevalence of T gondii (26% v 18%, P=0.027), hepatitis A virus (30% v 16%, P=0.004), and H pylori (18% v 15%, P=0.325) in atopic participants. Adjusted odds ratios of atopy decreased with a gradient of exposure to H pylori, T gondii, and hepatitis A virus (none, odds ratio 1; one, 0. 70; two or three, 0.37; P for trend=0.000045) but not with cumulative exposure to the other viruses. Conversely, total IgE concentration was not independently associated with any infection. Allergic asthma was rare (1/245, 0.4%) and allergic rhinitis infrequent (16/245, 7%) among the participants (245/1659) exposed to at least two orofecal and foodborne infections (H pylori, T gondii, hepatitis A virus). CONCLUSION: Respiratory allergy is less frequent in people heavily exposed to orofecal and foodborne microbes. Hygiene and a westernised, semisterile diet may facilitate atopy by influencing the overall pattern of commensals and pathogens that stimulate the gut associated lymphoid tissue thus contributing to the epidemic of allergic asthma and rhinitis in developed countries.
Notes: Journal Article
URL: http://www.bmj.com/cgi/content/full/320/7232/412
http://www.bmj.com/cgi/content/abstract/320/7232/412
Author Address: Laboratorio di Immunologia ed Allergologia, Divisione Aerea Studi Ricerche e Sperimentazioni, 00040 Pomezia, Rome, Italy. matricardi.pm.mclink.it


Title: High Microbial Turnover Rate Preventing Atopy: A Solution to Inconsistencies Impinging on the Hygiene Hypothesis?
Author: Matricardi, P. M.; Bonini, S.; (Date: Nov, 2000)
Journal: Clin Exp Allergy; V. 30; Issue: 11; Pages: 1506-10

Notes: Journal Article
Review
Review, Tutorial
Author Address: DASRS, RMAS, Laboratory of Immunology and Allergy, Pomezia, Rome, Italy.


Title: The Use of Antibiotics in the First Year of Life and Development of Asthma: Which Comes First?
Author: Mattes, J.; Karmaus, W.; (Date: Jun, 1999)
Journal: Clin Exp Allergy; V. 29; Issue: 6; Pages: 729-32

Notes: Editorial
Review
Review, Tutorial


Title: Pertussis Vaccination and Asthma: Is There a Link?
Author: Odent, M. R.; Culpin, E. E.; Kimmel, T.; (Date: Aug 24-31, 1994)
Journal: Jama; V. 272; Issue: 8; Pages: 592-3

Notes: Comment
Letter


Title: Give Us This Day Our Daily Germs
Author: Rook, G. A.; Stanford, J. L.; (Date: Mar, 1998)
Journal: Immunol Today; V. 19; Issue: 3; Pages: 113-6

Abstract: Modern vaccinations, fear of germs and obsession with hygiene are depriving the immune system of the information input upon which it is dependent. This fails to maintain the correct cytokine balance and fine-tune T-cell regulation, and may lead to increased incidences of allergies and autoimmune diseases. If humans continue to deprive their immune systems of the input to which evolution has adapted it, it may be necessary to devise ways of replacing it artificially.
Notes: Journal Article
Review
Review, Tutorial
URL: http://www.biomednet.com/library/fulltext/pii.S0167569997012048
Author Address: Dept of Bacteriology, UCL Medical School, London, UK. g.rook@ucl.ac.uk


Title: Clean Living Increases More Than Just Atopic Disease
Author: Rook, G. A.; (Date: May, 2000)
Journal: Immunol Today; V. 21; Issue: 5; Pages: 249-50

Notes: Comment
Letter
URL: http://www.biomednet.com/library/fulltext/IT.etd00310_01675699_v0021i05_00001630
http://www.biomednet.com/library/abstract/IT.etd00310_01675699_v0021i05_00001630


Title: The Inverse Association between Tuberculin Responses and Atopic Disorder
Author: Shirakawa, T.; Enomoto, T.; Shimazu, S.; Hopkin, J. M.; (Date: Jan 3, 1997)
Journal: Science; V. 275; Issue: 5296; Pages: 77-9

Abstract: Human immune responses are heterogeneous and may involve antagonism between T helper (TH) lymphocyte subsets and their cytokines. Atopy is characterized by immediate immunoglobulin E (IgE)-mediated hypersensitivity to agents such as dust mites and pollen, and it underlies the increasingly prevalent disorder asthma. Among Japanese schoolchildren, there was a strong inverse association between delayed hypersensitivity to Mycobacterium tuberculosis and atopy. Positive tuberculin responses predicted a lower incidence of asthma, lower serum IgE levels, and cytokine profiles biased toward TH1 type. Exposure and response to M. tuberculosis may, by modification of immune profiles, inhibit atopic disorder.
Notes: Journal Article
Author Address: Lung Research Laboratory, Osler Chest Unit, Churchill Hospital, Oxford OX3 7LJ, UK. jhopkin@immsvr.jr2.ox.ac.uk


Title: The Effect of Delipidated Deglycolipidated (Ddmv) and Heat-Killed Mycobacterium Vaccae in Asthma
Author: Shirtcliffe, P. M.; Easthope, S. E.; Cheng, S.; Weatherall, M.; Tan, P. L.; Le Gros, G.; Beasley, R.; (Date: May, 2001)
Journal: Am J Respir Crit Care Med; V. 163; Issue: 6; Pages: 1410-4

Abstract: Experimental and epidemiological evidence supports the hypothesis that exposure to mycobacteria has the potential to suppress the development of asthma and/or atopy and there are reports in the Chinese medical literature of repeated vaccination with inactivated BCG being effective in the management of asthma. Forty-three patients with stable moderately severe asthma who were skin prick test positive to house dust mite were randomized to receive two intradermal injections of either phosphate-buffered saline (placebo), heat-killed Mycobacterium vaccae (0.5 mg), or delipidated deglycolipidated Mycobacterium vaccae (DDMV) (0.05 mg). Markers of asthma severity were measured for 3 mo and blood eosinophil, IgE levels, and the T cell proliferative and cytokine responses were monitored. There were no significant differences between either treatment group and the placebo group for any of the outcome variables. There was also no difference between the treatment groups and placebo for eosinophil, IgE levels, or the T cell proliferative and cytokine response. The results indicate no effect of low dose intradermal DDMV or M. vaccae on asthma severity in patients with established asthma.
Notes: Clinical Trial
Journal Article
Randomized Controlled Trial
Author Address: Wellington Asthma Research Group, Department of Medicine, Wellington School of Medicine, Wellington South, New Zealand. pip@wnmeds.ac.nz


Title: Lipopolysaccharide Induces Relaxation in Lung Pericytes by an Inos-Independent Mechanism
Author: Speyer, C. L.; Steffes, C. P.; Tyburski, J. G.; Ram, J. L.; (Date: May, 2000)
Journal: Am J Physiol Lung Cell Mol Physiol; V. 278; Issue: 5; Pages: L880-7

Abstract: Lipopolysaccharide (LPS)-regulated contractility in pericytes may play an important role in mediating pulmonary microvascular fluid hemodynamics during inflammation and sepsis. LPS has been shown to regulate inducible nitric oxide (NO) synthase (iNOS) in various cell types, leading to NO generation, which is associated with vasodilatation. The purpose of this study was to test the hypothesis that LPS can regulate relaxation in lung pericytes and to determine whether this relaxation is mediated through the iNOS pathway. As predicted, LPS stimulated NO synthesis and reduced basal tension by 49% (P < 0.001). However, the NO synthase inhibitors N (omega)-nitro-L-arginine methyl ester, aminoguanidine, and N (omega)-monomethyl-L-arginine did not block the relaxation produced by LPS. In fact, aminoguanidine and N (omega)-monomethyl-L-arginine potentiated the LPS response. The possibility that NO might mediate either contraction or relaxation of the pericyte was further investigated through the use of NO donor compounds; however, neither sodium nitroprusside nor S-nitroso-N-acetylpenicillamine had any significant effect on pericyte contraction. The inhibitory effect of aminoguanidine on LPS-stimulated NO production was confirmed. This ability of LPS to inhibit contractility independent of iNOS was also demonstrated in lung pericytes derived from iNOS-deficient mice. This suggests the presence of an iNOS-independent but as yet undetermined pathway by which lung pericyte contractility is regulated.
Notes: Journal Article
URL: http://ajplung.physiology.org/cgi/content/full/278/5/L880
http://ajplung.physiology.org/cgi/content/abstract/278/5/L880
Author Address: Department of Surgery, Wayne State University, Detroit, Michigan 48201, USA.


Title: Exposure to Endotoxin or Other Bacterial Components Might Protect against the Development of Atopy
Author: von Mutius, E.; Braun-Fahrlander, C.; Schierl, R.; Riedler, J.; Ehlermann, S.; Maisch, S.; Waser, M.; Nowak, D.; (Date: Sep, 2000)
Journal: Clin Exp Allergy; V. 30; Issue: 9; Pages: 1230-4

Abstract: BACKGROUND: Several recent studies have shown that growing up on a farm confers significant protection against the development of atopy. These findings point particularly towards the importance of exposure to stable dust and farm animals. It has furthermore been reported that endotoxin, an intrinsic part of the outer membrane of gram negative bacteria, is abundant in environments where livestock and poultry is kept. The aim of this study was therefore to measure the level of environmental endotoxin exposure in homes of farmers’ children, children with regular contact to livestock and control children with no contact to farm animals. METHODS: Eighty-four farming and nonfarming families were identified in rural areas in Southern Germany and Switzerland. Samples of settled and airborne dust were collected in stables, and of settled dust indoors from kitchen floors and the children’s mattresses. Endotoxin concentrations were determined by a kinetic Limulus assay. RESULTS: Endotoxin concentrations were highest in stables of farming families, but were also significantly higher indoors in dust from kitchen floors (143 EU/mg vs 39 EU/mg, P < 0.001) and children’s mattresses (49479 EU/m2 vs 9383 EU/m2, P < 0.001) as compared to control children from nonfarming families. In addition, endotoxin levels were also significantly higher in mattresses and dust from kitchen floors in households where children had regular contact to farm animals (38.6 EU/mg and 23340 EU/m2, respectively) as compared to control subjects. CONCLUSION: We propose that the level of environmental exposure to endotoxin and other bacterial wall components is an important protective determinant for the development of atopic diseases in childhood.
Notes: Journal Article
Author Address: University Children’s Hospital Munich, Germany; Institute of Social and Preventive Medicine, University of Basel, Switzerland.


Title: Parasites and Asthma/Allergy: What Is the Relationship?
Author: Weiss, S. T.; (Date: Feb, 2000)
Journal: J Allergy Clin Immunol; V. 105; Issue: 2 Pt 1; Pages: 205-10

Abstract: Asthma prevalence is increasing in Western industrialized countries. The infectious theory of asthma onset hypothesizes that lower levels of IL-12 result in reduced T(H)1 stimulation and failure of the neonate to deviate from its T(H)2 bias at birth. Helminthic infections may influence T(H)2 immune responses and hence immune development. Although ecologic data would support a protective effect of parasitic infection on asthma development, this may be due to other exposures. To date, there is no conclusive evidence that parasitic infection protects against asthma development.
Notes: Journal Article
Review
Review, Tutorial
URL: http://www1.mosby.com/scripts/om.dll/serve?action=searchDB&searchDBfor=art&artType=abs&id=a104801&target=
Author Address: Department of Medicine, Harvard Medical School, and Channing Laboratory, Brigham & Women’s Hospital, Boston, MA 02115, USA.

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