Asthma progression to airway remodeling and bone marrow eosinophil responses in genetically distinct strains of mice

BACKGROUND

Patient factors that cause long-term airway remodeling are largely unidentified. This suggests that genetic differences may determine which asthmatic patients develop airway remodeling. A murine model with repeated allergen exposure leading to peribronchial fibrosis in complement factor 5 (C5)-deficient A/J mice has been used to study asthma progression. No studies have addressed the systemic effects of allergen sensitization or chronic allergen exposure on bone marrow eosinophilopoiesis in this mouse strain.

OBJECTIVE

To investigate bone marrow eosinophil responses during acute sensitization and chronic allergen exposure using genetically distinct mouse strains differing in persistent airway reactivity and remodeling.

METHODS

The C5-sufficient BALB/c and C5-deficient A/J mice were repetitively exposed to intranasal ovalbumin for 12 weeks. Subsequently, the mice were evaluated for airway eosinophilia, mucus-containing goblet cells, and peribronchial fibrosis. Both strains of mice were also acutely sensitized to ovalbumin. Bone marrow eosinophil progenitor cells and mature eosinophils were enumerated.

RESULTS

BALB/c and A/J mice have similar bone marrow responses after acute allergen exposure, with elevations in bone marrow eosinophil progenitor cell and eosinophil numbers. After chronic allergen exposure, only C5-deficient A/J mice that developed peribronchial fibrosis exhibited bone marrow eosinophilia. BALB/c mice lacked peribronchial fibrosis and extinguished accelerated eosinophil production after long-term allergen challenge.

CONCLUSIONS

Chronic airway remodeling after repeated allergen exposure in genetically different mice correlated with differences in long-term bone marrow eosinophilopoiesis. Preventing asthma from progressing to chronic airway remodeling with fibrosis may involve identifying genetically determined influences on bone marrow responses to chronic allergen exposure.

Otitis media as a presenting complaint in childhood immunodeficiency diseases

Otitis media is one of the most common childhood infections and may result from a variety of underlying problems. Suspicion of immunodeficiency should increase when ear infections are frequent; suppurative; unresponsive to antibiotics; caused by unusual organisms; or seen in the context of other frequent infections, severe eczema, or failure to thrive. Humoral immune deficiencies, particularly with an inability to make antibody to encapsulated organisms, are the immunodeficiencies most likely to cause increased otitis media. Immune system evaluation should concentrate on humoral immunodeficiency disorders, but the presenting history and physical findings also should be considered when designing the work-up. Treating the underlying immune deficiency is usually necessary to adequately control the ear infections.

Prevalence of allergic sensitization to indoor fungi in West Virginia

Exposure to indoor fungi is of growing concern in residential and occupational environments in the United States. The purpose of this study was to determine the prevalence of sensitization to common indoor fungal species in an atopic population. We evaluated 102 patients (73 female and 29 male patients) for immunoglobulin E (IgE) reactivity to a panel of skin-prick test (SPT) reagents used for routine allergy testing. Patients also were tested for six additional fungi that are common indoor contaminants. All patients had symptoms consistent with allergic rhinitis or asthma. The presence of specific IgE against the fungal species was determined using immunoblotting. Of the 102 eligible patients, 68% had at least one positive skin test. The most prevalent positive SPTs were to dust mites, cats, vernal grass, and short ragweed. Overall, 21/102 (21%) patients with asthma or allergic rhinitis were skin test positive to at least one fungal extract. Of the patients with a positive SPT to fungi, 12/21 (58%) showed sensitivity to one or more of the newly tested species; most notably Trichoderma viride (8%), Chaetomium globosum (7%), Paecilomyces variotii (7%), and Acremonium strictum (6%). Immunoblotting revealed specific IgE against a number of protein bands belonging to these fungal species. The prevalence of fungal sensitization was common, particularly for indoor fungal contaminants that are not routinely included in SPT panels. Cross-reactivity with other fungi may partially explain our results; however, skin testing for these indoor fungi may provide useful diagnostic information.

Prevalence of pollen sensitization in younger children who have asthma

It is commonly believed that young children are incapable of pollen sensitization; therefore, skin testing usually is not performed to these allergens. The purpose of this study was to identify the frequency of positive skin tests to outdoor allergens among younger children who have asthma. Patients who have asthma, aged 6 months to 10 years, were evaluated for pollen sensitization over a 10-year period. Skin-prick testing was performed to relevant individual aeroallergens including trees, grasses, and weeds. Testing for perennial indoor allergens such as dust mites, cats, dogs, cockroaches, and molds was performed also. A total of 687 children with asthma were evaluated. No child <12 months old was sensitized to pollens. Children between 12 and 24 months of age had a 29% incidence of pollen sensitization. Three-year-old children were as likely to be skin test positive to pollen as an indoor allergen. Notably, 49% of 3- and 4-year olds were sensitized to outdoor allergens. Primary sensitizing pollens in this age group were short ragweed, box elder, and June grass. In this population, pollen sensitization was not related to tobacco or wood smoke exposure. Although it is widely believed that young children with asthma are most commonly allergic to indoor allergens, almost 40% of our 1- to 3-year old children with asthma showed IgE-mediated sensitivity to outdoor allergens. Pediatric allergists should consider performing skin-prick testing to their local common aeroallergens in young children with asthma and seasonal symptoms.

Spectrum of illness in pediatric common variable immunodeficiency

BACKGROUND

Common variable immunodeficiency (CVID) may present at any age but usually presents during adulthood.

OBJECTIVE

To study the presentation and associated medical conditions found in pediatric patients with CVID.

METHODS

A medical record review of patients diagnosed as having CVID before the age of 18 years was performed at a tertiary care immunology clinic from 1992 to 2005. Inclusion criteria consisted of presentation with recurrent infections and decrease in 2 of 3 immunoglobulin isotypes (IgG, IgA, IgM) 2 SDs below the age-specific range, with a poor or absent response to immunization. There had to be no other identifiable predisposing cause of the immunodeficiency.

RESULTS

A total of 12 patients were identified. The mean age at presentation was 8 years. All patients had low IgG levels with poor functional antibody responses. The most common presenting infections were sinusitis (75%), otitis media (67%), and pneumonia (58%). Bronchiectasis was seen in 3 children. One patient presented with chronic diarrhea due to Giardia. Two patients presented with failure to thrive. Asthma was seen in 10 patients (83%) but was usually diagnosed after the initial presentation. Autoimmune disorders were seen, including 1 patient with idiopathic thrombocytopenia and 2 with neutropenia. Other disorders encountered were growth hormone deficiency, hypothyroidism, end-stage renal disease, and sarcoma.

CONCLUSIONS

CVID is a difficult diagnosis in the pediatric population because of an unpredictable presentation. Autoimmune disease, growth hormone deficiency, renal disease, and cancer were noted in our population. A high incidence of asthma also may be associated with pediatric CVID.

Child and caregiver psychosocial functioning in pediatric immunodeficiency disorders

BACKGROUND

Children with chronic illness have been found to be at an increased risk of behavioral and emotional difficulties. To date, children with pediatric immunodeficiency disorders (PIDDs) and their families have not been the focus of extensive published psychosocial research.

OBJECTIVE

To determine if children with PIDDs and their caregivers have altered psychosocial function and whether the severity of the PIDD was associated with such difficulties.

METHODS

Twenty children with PIDDs and 20 children with asthma were recruited for this study. Children and their caregivers completed various psychosocial questionnaire forms. Responses were compared with normative data for the appropriate measure and with other variables.

RESULTS

Higher frequencies of children with PIDDs were found to have a number of elevated psychosocial concerns when contrasted with normative data, particularly from parent report. These concerns included depression, anxiety, somatization, social withdrawal, and social skills. The severity of the PIDDs was significantly associated with a number of behavioral adjustment issues, including receiving psychiatric diagnoses and special education services. Although children with PIDDs had significantly more psychiatric diagnoses than did asthmatic children, these groups did not differ significantly on questionnaire scores regarding child or caregiver psychosocial adjustment.

CONCLUSIONS

Children with PIDDs have significant behavioral problems. Children receiving intravenous immunoglobulin or immunomodulatory treatments were reported to have more problems than children not receiving them. This study highlights the need for further research in psychosocial functioning of children with PIDDs in an effort to develop interventions to promote their overall adjustment.

Modern prevalence of insect sensitization in rural asthma and allergic rhinitis patients

Inhalant allergy to insects other than cockroaches and dust mites was described in the 1950s, but little attention has been paid to these findings. Sensitization rates for many allergens have increased since then. In this rural population, we describe the current prevalence of sensitization to commonly found insects. We evaluated 200 patients (38 adults and 162 children), for immunoglobulin E (IgE)-mediated sensitization to the caddis fly, mayfly, moth, carpenter ant, and housefly using the prick technique and commercially available whole-body extracts. All had symptoms consistent with asthma and/or allergic rhinitis. They also were tested to indoor and outdoor aeroantigens. Of the 200 patients, 60 patients (30%) tested positive to at least one of the five insects. The most prevalent positive skin test was to the mayfly (37/60), followed by the housefly (36/60), caddis fly (27/60), moth (14/60), and ant (10/60). Of the 60 patients positive for insects, 35 patients (58%) also tested positive to at least one species of mite, 36 patients (60%) tested positive to the cockroach. Twelve of the 60 patients (20%) with positive insect testing did not react to either cockroaches or mites. In our patients, the immunoglobulin E-mediated sensitization rate to insects excluding cockroaches is 30%. Many patients also were sensitized to mites and/or cockroaches. These insects are all present in the indoor/outdoor environment of this rural population. Cross-reactivity with mites and cockroaches (insect panallergy) may partially explain our results. The presence of skin test sensitivity in the absence of cockroach or mite allergy suggests possible true insect sensitization.

Ten-year experience using a plastic, disposable curette for the diagnosis of primary ciliary dyskinesia

BACKGROUND

Primary ciliary dyskinesia (PCD) results in impaired mucociliary clearance. Patients with this disorder develop chronic sinopulmonary disease with recurrent sinusitis, otitis media, nasal polyposis, pneumonia, and, ultimately, bronchiectasis. Other associated findings of dysfunctional ciliary activity include situs inversus, dextrocardia, and infertility.

OBJECTIVE

To describe our 10-year experience using a small, plastic, disposable curette to perform a screening procedure for cilia function and to collect samples for electron microscopy.

METHODS

In the past 10 years, we screened infants and children with severe chronic sinusitis and other chronic recurrent upper respiratory tract problems for PCD by using a plastic, disposable curette to collect tissue samples from the nasal mucosa. Samples were placed in sterile saline and examined under light microscopy for the presence of cilia. Failure to note ciliary movement prompted another examination 1 month later. If no functional cilia were noted at the follow-up examination, a specimen was obtained and sent for electron microscopy.

RESULTS

We identified 7 patients with PCD; 2 had situs inversus totalis. Average age at diagnosis was 3 years. The most common symptom at presentation was frequent upper respiratory tract infections with severe otitis media (7 patients) and sinusitis (5 patients). Recurrent pneumonia was present in 6 patients. Dynein arm deficiency was the most common electron microscopic diagnosis.

CONCLUSIONS

Evaluating children for PCD by using a plastic, disposable curette is a relatively simple procedure that could be used by allergists in practice. Primary ciliary dyskinesia occurs frequently enough that physicians should consider it as part of the differential diagnosis in evaluating children with recurrent, severe sinopulmonary infections.

Regulation of eosinophilopoiesis in a murine model of asthma

Eosinophilic inflammation plays a key role in tissue damage that characterizes asthma. Eosinophils are produced in bone marrow and recent observations in both mice and humans suggest that allergen exposure results in increased output of eosinophils from hemopoietic tissue in individuals with asthma. However, specific mechanisms that alter eosinophilopoiesis in this disease are poorly understood. The current study used a well-characterized murine animal model of asthma to evaluate alterations of eosinophil and eosinophil progenitor cells (CFU-eo) in mice during initial sensitization to allergen and to determine whether observed changes in either cell population were regulated by T lymphocytes. Following the first intranasal installation of OVA, we observed sequential temporal elevation of eosinophils in bone marrow, blood, and lung. In immunocompetent BALB/c mice, elevation of bone marrow eosinophils was accompanied by transient depletion of CFU-eo in that tissue. CFU-eo rebounded to elevated numbers before returning to normal baseline values following intranasal OVA exposure. In T cell-deficient BALB/c nude (BALB/c(nu/nu)) mice, CFU-eo were markedly elevated following allergen sensitization, in the absence of bone marrow or peripheral blood eosinophilia. These data suggest that eosinophilia of asthma results from alterations in two distinct hemopoietic regulatory mechanisms. Elevation of eosinophil progenitor cells in the bone marrow is T cell independent and likely results from altered bone marrow stromal cell function. Differentiation of eosinophil progenitor cells and phenotypic eosinophilia is T cell dependent and does not occur in athymic nude mice exposed to intranasal allergen.

Providing dust mite-proof covers improves adherence to dust mite control measures in children with mite allergy and asthma

INTRODUCTION

The most critical dust mite avoidance technique for asthmatic children with mite allergy is the use of dust mite-proof bedding covers. Adherence to allergen control measures is poor due to cost. The purpose of this study was to determine whether giving families mite-proof bedding encasings at the time of the diagnosis with mite allergy would improve adherence at a home visit 2 months later.

METHODS

Parents of children (mean age 7.7 years) with asthma and positive skin tests for dust mite were assigned either to an intervention group, which received dust mite covers upon enrollment or a comparison group, which did not. Both groups were instructed in dust mite control measures by a medical provider and told to invest in the covers as part of standard care. Two months after enrollment, parent report and observational measures from each family were obtained during a home visit.

RESULTS

The group provided allergen encasings was found to be significantly more likely to have used the casings at the home visit, t(22) = 2.77, P < 0.05. There were no differences between groups in adherence to other mite control strategies. Parenting stress was significantly related to poorer mite control compliance. The most common reason reported for nonadherence to control measures was cost.

CONCLUSIONS

Providing mite bedding encasings at the time of diagnosis significantly increases compliance at a 2-month home visit. Medicaid and insurance companies should be encouraged to pay for casings as a cost effective measure to improve asthma care in children with mite allergy.

Mouse allergy among asthmatic children from rural Appalachia

BACKGROUND

Mice are a common finding in the indoor environment of many homes. In a recent study, 18% of children with asthma from an inner-city environment were reported to be allergic to mouse allergen.

OBJECTIVE

To determine the frequency of skin test reactivity among asthmatic children in a rural environment.

METHODS

We consecutively evaluated 209 (82 female, 127 male) children between the ages of 5 months and 19 years with asthma for mouse allergy. A careful environmental history was obtained on all children. Children older than 3 years of age were skin tested to mouse allergen and other indoor/outdoor inhalant allergens. Children younger than 3 years were skin tested to mouse and indoor allergens.

RESULTS

Thirty-three percent of parents reported seeing mice in their homes. Overall, 25 of 209 (12%) children with asthma were skin test-positive for mouse. For children 3 years or younger, 6 of 52 were skin test-positive for mouse (12%). There was no correlation among socioeconomic status, skin test reactivity, and the presence of mice in the home. Children with multiple skin test reactions were more likely to be reactive to mouse (P < 0.01). Mice seen in the home did not correlate with positive mouse skin tests.

CONCLUSIONS

The frequency of skin test reactivity to mouse allergen in asthmatic children from rural areas appears slightly less than that in children from inner-city environments. However, a frequency of 12% suggests that skin testing for this allergen provides useful information for environmental control measures in the home.

Asthma in the school-aged child

Understanding the role of inflammation in childhood asthma has led to major changes in the approach to management of this disease. Based on the guidelines from the NIH, inhaled long-term control medications that target the underlying inflammatory processes in asthma are now recommended as the mainstay of drug treatment. Long-term control medications are recommended for all children who have asthma symptoms that occur more frequently than twice weekly or nocturnal symptoms more than twice monthly. Environmental control measures to decrease allergen exposure are important, as is attention to sinusitis and GER. The main impediment to improved asthma care is poor patient compliance. Many patients do not understand the role and importance of prophylactic medications in asthma treatment. Further, inconvenient dosing regimens, difficulties with metered-dose inhalers, and fear of potential side effects have all contributed to poor patient compliance. Increased efforts at patient education are needed to improve adherence to asthma plans. These efforts at improving patient compliance, along with improved physician adherence to the guidelines from the NIH, are needed to decrease the morbidity and mortality of childhood asthma.

Clinical and molecular analysis of patients with defects in micro heavy chain gene

Autosomal recessive disorders of B cell development are rare and heterogeneous. To determine the proportion of affected patients who have defects in the micro heavy chain (IGHM) gene, we used single-stranded conformational polymorphism analysis to screen genomic DNA from 40 unrelated patients with early onset infections, profound hypogammaglobulinemia, and absent B cells. All of the patients were genotypically normal in BTK, the gene that underlies X-linked agammaglobulinemia. Eight different mutations in the micro heavy chain were identified in 19 members of 12 unrelated families. Four of the mutations were large deletions that removed more than 40 kb of DNA in the IGHM locus. In six of the 12 families, the affected patients had an identical single base pair substitution, a G-->A, at the -1 position of the alternative splice site. Immunoglobulin haplotype analysis showed that this mutation occurred on at least three different haplotypes, indicating that this is a hot spot for mutations. Compared with patients with mutations in Btk, patients with defects in the micro heavy chain had an earlier onset of disease and more complications. Our study indicates that at least 20-30% of patients with autosomal recessive defects in B cell development have mutations in the micro heavy chain.

IL-5 production by bone marrow stromal cells: implications for eosinophilia associated with asthma

BACKGROUND

Eosinophil infiltration of bronchial tissue is a hallmark of asthma. Recruitment of eosinophils into pulmonary tissue is dependent on the presence of IL-5. In addition, IL-5 plays a significant role in the differentiation, proliferation, and maturation of eosinophil progenitor cells in the bone marrow before recruitment into the lung. The contribution of bone marrow eosinophil production to eosinophilia associated with asthma is poorly understood.

OBJECTIVE

The aims of this study were to determine whether bone marrow stromal cells produce IL-5 and to determine whether IL-5 production by stromal cells is upregulated by IL-1, an inflammatory cytokine associated with asthma.

METHODS

IL-5 messenger (m)RNA from bone marrow stromal cells was amplified by RT-PCR and sequenced. Stromal cells were lysed, and IL-5 protein production was measured by ELISA. Upregulation of stromal cell IL-5 transcription, translation, and functional effect on eosinophil differentiation was evaluated after stimulation with recombinant IL-1alpha and IL-1beta and compared with untreated cells.

RESULTS

Bone marrow stromal cells transcribe and translate IL-5. The nucleotide sequence of IL-5 mRNA from stromal cells was identical to that previously reported for murine T cells. IL-5 mRNA abundance in stromal cells increased with increasing cell confluence in culture. IL-5 mRNA and protein levels were upregulated by exposure of stromal cells to the inflammatory cytokines IL-1alpha and IL-1beta. Exposure of stromal cells to IL-1 resulted in increased eosinophil differentiation in coculture experiments with nonadherent bone marrow cells.

CONCLUSION

The production of IL-5 mRNA and protein by bone marrow stromal cells is a novel finding that has implications for both normal eosinophilopoiesis and development of the accelerated eosinophil production associated with asthma.

Cockroach and other inhalant allergies in infantile asthma

BACKGROUND

Infantile asthma is commonly thought to be caused by viral respiratory infections and exposure to second-hand cigarette smoke. Allergy has not been felt to be a major cause of infantile asthma and infants and small children are not commonly skin tested.

OBJECTIVE

To determine the frequency of skin test reactivity in asthmatic children less than 3 years of age.

METHODS

We evaluated 196 (50 female/146 male) children with infantile asthma for allergy. Infantile asthma was defined as three or more episodes of wheezing in a child less than 3 years of age. A careful environmental history was obtained on all children. All were skin tested to alternaria, cat, dog, cockroach, and house dust mites (HDM) extracts using the prick technique with the Greer Dermapik.

RESULTS

Forty-five percent of the infants and children tested had at least one positive skin test. 51/196 (26%) of the children were skin test positive to cockroach, 17.3% to HDM, 13.8% to cat, 6.6% to alternaria, and 6.1% positive to dog. For the 49 children who were less than 1 year of age, 28.5% were positive to cockroach, 10.2% to HDM, 10.2% to cats, 4% to alternaria, and 0% to dog.

CONCLUSIONS

Allergy to cockroach and other indoor allergens may be a significant contributor to infantile asthma in a rural setting. Skin testing children with infantile asthma may provide useful information for institution of environmental controls measures in the child's home.

Renal transplantation in a patient with common variable immunodeficiency

A 15-year-old girl developed end-stage renal disease requiring renal transplantation. Posttransplantation immunosuppression therapy consisted of antithymocyte globulin, glucocorticosteroids, cyclosporine A, and azathioprine. The patient's clinical course after transplantation was complicated by several episodes of graft rejection, chronic anemia, oral candidiasis, and numerous infections of the sinopulmonary tract that were recalcitrant to antibiotics and surgical intervention. An immunologic evaluation showed marked immune abnormalities beyond that expected by the transplant immunosuppression. Examination of serum samples taken before the transplant confirmed a diagnosis of common variable immunodeficiency. The difficulties of managing posttransplantation immunosuppression in a patient with a primary immunodeficiency are discussed. Patients with end-stage renal disease and a history of recurrent sinopulmonary infections may require immunologic screening before renal transplantation.