The Duffy antigen receptor for chemokines regulates asthma pathophysiology

BACKGROUND

The Duffy antigen receptor for chemokines (DARC) is an atypical receptor that regulates pro-inflammatory cytokines. However, the role of DARC in asthma pathophysiology is unknown.

OBJECTIVE

To determine the role of DARC in allergic airways disease in mice, and the association between DARC single nucleotide polymorphisms (SNPs) and clinical outcomes in patients with asthma.

METHODS

Mice with targeted disruption of the Darc gene (Darc∆E2 ) or WT mice were challenged over 3 weeks with house dust mite (HDM) antigen. Allergic airways disease was assessed 24 hours and 7 days following the final challenge. Additionally, associations between DARC SNPs and clinical outcomes were analysed in a cohort of poorly controlled asthmatics.

RESULTS

Total airway inflammation following HDM did not differ between Darc∆E2 and WT mice. At 24 hours, Darc∆E2 mice had increased airway hyperresponsiveness; however, at 7 days airway hyperresponsiveness had completely resolved in Darc∆E2 but persisted in WT mice. In poorly controlled asthmatics, DARC SNPs were associated with worse asthma control at randomization and subsequent increased risk of healthcare utilization (odds ratio 3.13(1.37-7.27), P=.0062).

CONCLUSIONS AND CLINICAL RELEVANCE

Our animal model and human patient data suggest a novel role for DARC in the temporal regulation in asthma pathophysiology and symptoms.

Modulation by sodium butyrate of the differentiated status of a clonal pancreatic B-cell line (RIN)

RINmRH cells are a cloned cell line derived from a transplantable rat insulinoma. These cells display only some of the differentiated structure/function features of native pancreatic B-cells. In particular, they do not efficiently or reproducibly express islet B-cell surface antigens, which would otherwise render them useful for screening for the presence of anti-islet cell surface antibodies in the serum of suspected diabetic patients or their relatives. This study examines whether sodium butyrate can enhance expression of B-cell differentiation antigens on RIN cells. RIN cells were exposed to 1,2 or 4 mM butyrate for nine days, and cell growth followed. At 1 mM, butyrate inhibited cell growth by 90%. At the higher concentrations, there was a net loss in the number of cells per culture dish. Exposing the cells to 1 mM or 2 mM butyrate for two days, resulted in a 50% increase in cellular insulin content at the expense of a partial (1 mM) or complete (2 mM) loss of stimulated insulin release in response to glyceraldehyde or serine. A concentration of 1 mM butyrate was therefore used for subsequent studies. The binding to RIN cells of a panel of monoclonal antibodies (mAb's) known to bind native islet cells (R2D6, A2B5, A1D2, 3G5) as well as of serum from a diabetic patient known to carry anti-islet cell antibodies, was screened by cytofluorography or by a radio-binding assay. The relative binding affinity of the mAb's was 3G5 greater than A1D2 greater than A2B5 greater than R2D6. Only 2-3% of the cells were bound by the diabetic patient serum.(ABSTRACT TRUNCATED AT 250 WORDS)

Epidemiology of infection by nontuberculous mycobacteria. VIII. Absence of mycobacteria in chicken litter

Overlap in the geographic distributions of (1) higher frequencies of persons reacting to antigens prepared from the Mycobacterium avium, M. intracellulare, and M. scrofulaceum (MAIS) group; (2) higher frequencies of isolation from natural waters and soils; (3) higher densities of farms producing broilers (chicken) in the southeastern United States raises the question of whether MAIS organisms occur abundantly in chicken litter (pine bark shavings containing avian fecal material) and whether litter may be a potential source of animal or human infection through its subsequent use as a fertilizer or feed supplement. We show here that potentially pathogenic mycobacteria were seldom recovered from chicken litter containing avian fecal material. Further, litter appears bactericidal to these organisms in that less than 1% of cells inoculated survived more than 6 wk, probably because of the high pH of litters.

Identification of cytoplasmic membrane protein antigens of Mycobacterium avium, M. intracellulare, and M. scrofulaceum

The cytoplasmic membrane isolated from representative strains of the Mycobacterium avium, M. intracellulare, and M. scrofulaceum (MAIS) group contained approximately 20 proteins, as identified by SDS - polyacrylamide gel electrophoresis. One membrane protein predominated, comprising up to 50% of the total membrane protein. This major cytoplasmic membrane protein (MCMP) had a molecular weight of 31,000 and was surface accessible based on its susceptibility to proteinase digestion. The composition of the culture medium strongly influenced the amount of MCMP in the membrane fraction. Western blot analysis revealed that the MCMP and several other membrane proteins reacted with serum samples from patients infected with M. avium-intracellulare, M. tuberculosis, or other mycobacteria.

Premature menopause: monoclonal antibody defined T lymphocyte abnormalities and antiovarian antibodies

The presence of other organ-specific autoimmune disorders in some patients with premature menopause has supported the concept of an autoimmune etiology. The authors analyzed the peripheral blood of 23 women with the diagnosis of premature menopause to detect the presence of monoclonal antibody-defined T-lymphocyte abnormalities and/or antiovarian antibodies. All subjects were less than 40 years of age with the duration of menopause ranging from less than 1 year to 11 years at the time of study. Thirty-five percent of the subjects had an elevated percentage of Ia+ (Dr-activated) T cells using monoclonal antibody L243. The percent T4 (helper) T8 (suppressor/cytotoxic) T cells and T4/T8 ratio were normal in the study group. Four subjects (approximately 17%) had elevated percentages of the age-related 3G5+ T cell subset. Two of the subjects with increased 3G5+ T cells also exhibited increased Ia+ T cells. Antiovarian steroid cell antibodies and antiadrenal cortical antibodies were present in approximately 9% of subjects. Anti-islet cell antibodies were not present. Thyroid antimicrosomal antibodies were present in 17% of subjects. Study subjects exhibited immunologic abnormalities that the authors hypothesize may play a role in the development of premature menopause in a larger percentage of patients than was previously suspected.

Trisomy 21 (Down's syndrome): autoimmunity, aging and monoclonal antibody-defined T-cell abnormalities

Down's syndrome has been associated with organ-specific autoimmunity and 'premature aging'. We studied 27 individuals with Down's syndrome (all trisomy 21, no translocations aged 0.5 to 50 years). Subjects were not preselected for autoimmunity. Six subjects had a history of hypothyroidism and three additional subjects had anti-microsomal antibodies (euthyroid). Three subjects had insulin-dependent diabetes mellitus and one additional subject had islet cell autoantibodies (non-diabetic). The percentage Ia (Dr) positive T cells exceeded the normal range in 7/26 (27%). The percent CD4+ and CD8+ T cells were not significantly different from control. A subgroup of Down's syndrome subjects (less than age 10) had a premature increase in the percentage of 3G5+ (age-related) T cells. Normal individuals express a similar percentage of 3G5+ T cells at age 50 to 70 years. The presence of T-cell activation and 'premature T-cell aging' may predispose Down's syndrome subjects to organ-specific autoimmunity and age-related disorders.

Altered differentiated cell surface properties of transformed (RINm5F) compared with native adult rat pancreatic B cells

RINm5F cells, a line derived from a rat insulinoma, are frequently used as a model for studying pancreatic B cell structure and function. These transformed cells are known, however, to be different from native B cells in a number of biochemical respects. We have now compared the surface features of RIN cells and native B cells in two different ways: 1) Dispersed cells from islet obtained from adult rats can reassociate spontaneously in culture to form aggregates (pseudoislets) with cellular organization similar to that of intact native islets (a central B cell core surrounded by a discontinuous mantle of non-B cells). Native islet cells and RIN cells were mixed together and allowed to reaggregate. Examination by immunocytochemistry and transmission electron microscopy showed that the aggregates contained all cell types present in the original mixed cell suspension (native B- and non-B cells, and RIN cells). The native B cells were centrally located, surrounded by zones of non-B cells, as in islets. The RIN cells, however, were restricted to the periphery and as such not recognized as native B cells. 2) R2D6, a monoclonal antibody, binds selectively to a ganglioside on the surface of islet B, but not non-B, cells. The role of this ganglioside is not known. RIN cells were incubated with R2D6 followed by a fluorescently labeled second antibody. Analysis by flow cytofluorometry indicated that the monoclonal antibody had bound (stained) only 3-15% of the RIN cells. These R2D6 positive cells were sorted from R2D6 negative cells and subsequently shown to have a lower DNA content. Expression of the R2D6 target ganglioside on RIN cells thus appears to be cell cycle dependent. Based on two different criteria, RINm5F cells do not therefore share surface features in common with native B cells. The cell cycle dependent expression of a B cell surface antigen by the RIN cells might, however, be a useful model for studying the regulation of ganglioside turnover.

A monoclonal antibody (3G5)-defined ganglioside antigen is expressed on the cell surface of microvascular pericytes

The identification of microvascular pericytes in vitro relies principally on morphological characteristics and growth dynamics, as there is a paucity of immunochemical markers for these cells. Consequently, an attempt was made to identify mAb reagents that would aid in both the rapid identification and enrichment of retinal capillary pericytes in vascular cell cultures. A panel of mAbs raised by xenogeneic immunization of mice with various tissues was screened for immunoreactivity with dissociated cultures of bovine retinal capillary pericytes. Two antibodies from the panel (3G5 and HISL-8) were seen to react with pericytes by indirect immunofluorescence. The mAb 3G5 was selected for further study. mAb 3G5 did not react with dissociated cultures of smooth muscle cells, endothelial cells, or retinal pigmented endothelial cells. The pericyte 3G5 antigen was insensitive to the action of trypsin; therefore, mAb 3G5 was used to selectively purify pericytes from trypsinized mixed retinal cell cultures by flow cytometry. 3G5+ pericytes (representing 8% of cells in a mixed retinal cell culture) were enriched at least nine-fold to represent greater than 70% of cells. The mAb 3G5 stained retinal capillaries in vivo with a fluorescence distribution consistent with pericyte staining. The 3G5 antigen of cultured pericytes was found to be a glycolipid of mobility intermediate between ganglioside markers GM1 and GM2.

Spontaneous reassociation of dispersed adult rat pancreatic islet cells into aggregates with three-dimensional architecture typical of native islets

Islets of Langerhans consist of four major endocrine cell types assembled in a highly organized manner critical for their function. The molecular forces governing islet cellular architecture are not understood. We determined whether adult rat islet cells carry information necessary for orderly assembly. Dispersed cells from adult rat islets were maintained in static suspension culture for 6 days. During this time the cells reassociated to form numerous aggregates. These aggregates were approximately half the size of native islets with a commensurate reduction in DNA and insulin content. However, both cellular composition and organization were remarkably similar to that of adult rat islets, in which the beta-cells form a central core surrounded by a discontinuous mantle of non-beta-cells. Thus, immunoperoxidase staining showed that in the aggregates, just as in intact islets cultured in parallel, 26% of the cells were non-beta-cells and of these, 94% were clearly peripheral. Non-beta-cells were similarly found to be peripheral, with beta-cells located centrally, even when the ratio of non-beta-cells to beta-cells had been altered. This was achieved by sorting the two cell populations by fluorescence-activated flow cytometry, resulting in aggregates with 79% non-beta-cells and 21% beta-cells. Insulin release from the aggregates was stimulated approximately ninefold by raising glucose from 50 to 300 mg/dl, which was comparable to that found for intact islets. The spontaneous formation of isletlike aggregates displaying appropriate cellular architecture indicates that the signals (molecules) needed for such organization are intrinsic to islet cells and are still expressed by them in adult life.

Aging in man. Linear increase of a novel T cell subset defined by antiganglioside monoclonal antibody 3G5

A new human T cell subset defined by antineuronal ganglioside mAb 3G5 increases linearly with advancing age in man. The percentage of circulating 3G5+ T cells in 21 normal individuals, quantitated by cytofluorograph analysis, increases linearly from age 7 (23-30%) to age 84 (58%) (r = 0.85, p less than 0.001). The antigen on T cells has the biochemical properties of a ganglioside that migrates between GM1 and GM2 ganglioside markers on TLC. The 3G5 subset represents the first T cell subset that reflects aging in man.

Congenital rubella. Monoclonal antibody-defined T cell abnormalities in young adults

In order to determine if congenital rubella infection is associated with persistent T cell abnormalities, T cell subsets were quantitated in 16 non-institutionalized subjects (ages nine to 21) with the clinical stigmata and history of congenital rubella. Flow cytometric analysis revealed a decreased T4/T8 ratio (mean +/- SEM in subjects with rubella, 1.57 +/- 0.15, p less than 0.01; in normal subjects, 2.3 +/- 0.4; in subjects with type I diabetes, 2.3 +/- 0.3), decreased percent of T4-positive "helper" cells (42.6 +/- 2.3) different from that in both normal subjects (52.6 +/- 2.4, p less than 0.01) and subjects with recent-onset diabetes (51.5 +/- 2.4), and increased percent of T8-positive "suppressor/cytotoxic" T cells (29.9 +/- 1.4, p less than 0.02) relative to that in normal subjects (24.2 +/- 1.5) and subjects with type I diabetes (23.9 +/- 1.4). Five of 16 subjects with congenital rubella had an elevation of la-positive T cells. Approximately 20 percent had antimicrosomal antibodies. One subject had diabetes mellitus and hypothyroidism, one had hypoglobulinemia, and one had previously undiagnosed hyperthyroidism. Glycosylated hemoglobin levels were normal in all except the diabetic subject, and none of the subjects was islet cell antibody-positive. The T cell abnormalities documented may predispose persons with congenital rubella to the development of organ-specific autoimmunity.

Amiodarone therapy and autoimmune thyroid disease. Increase in a new monoclonal antibody-defined T cell subset

T cell subsets in 10 patients receiving amiodarone were evaluated, and their thyroid function and antithyroid antibodies were assessed. A generalized increase in a recently discovered subset of T cells expressing a complex ganglioside antigen reacting with monoclonal antibody 3G5 was found. Two patients, one with hyperthyroidism and the other with euthyroid Graves' ophthalmopathy, had an additional T cell abnormality--marked increase in Ia-positive T cells (an abnormality typical of patients with spontaneous Graves' disease). In the hyperthyroid patient, the Ia-positive T cells disappeared within three weeks after amiodarone was discontinued. The other patients receiving amiodarone had normal numbers of Ia-positive T cells. These studies indicate that amiodarone alters a major resting T cell subset for almost all patients and is associated with T cells expressing the Ia antigen in selected patients. These T cell abnormalities suggest that amiodarone precipitates organ-specific autoimmunity in susceptible persons.

Selective medium for the isolation and enumeration of Mycobacterium avium-intracellulare and M. scrofulaceum

A medium for the selective isolation and enumeration of Mycobacterium avium-intracellulare and M. scrofulaceum (MAIS) was developed, based upon the ability of these mycobacteria to utilize Tween 80 as sole carbon source and grow optimally at pH 5.5 on a simple mineral salts medium. Representative MAIS strains had higher efficiencies of plating on the Tween 80 medium compared with Middlebrook 7H10. It was shown that nonmycobacterial organisms in natural waters had lower efficiencies of plating on the Tween 80 medium and smaller colonies, thus allowing direct isolation and enumeration of the slowly growing mycobacteria without overgrowth.

Recovery and survival of nontuberculous mycobacteria under various growth and decontamination conditions

The survival of microorganisms of the Mycobacterium avium, M. intracellulare, and M. scrofulaceum (MAIS) complex was evaluated after various soil and water decontamination regimens. Survival was reduced by growing cells in natural waters compared with laboratory media and by inclusion of malachite green in media as an antifungal agent. Decontamination with benzalkonium chloride, while reducing survival significantly less than 1% NaOH, failed to eliminate many fungi. Recovery from soil was further reduced by transfer losses and by irreversible cell adsorption onto particulates.

In vitro susceptibility of human and environmental isolates of Mycobacterium avium, M. intracellulare, and M. scrofulaceum to heavy-metal salts and oxyanions

Because of the widespread distribution of Mycobacterium intracellulare and M. scrofulaceum in southeastern U.S. waters, the susceptibility of members of these species to heavy-metal salts and oxyanions was investigated. Isolates with abnormally high tolerance to mercuric chloride or cadmium chloride were identified.

Uric acid utilization by Mycobacterium intracellulare and Mycobacterium scrofulaceum isolates

Forty-nine human and environmental isolates of Mycobacterium intracellulare and Mycobacterium scrofulaceum were tested for their ability to grow on uric acid and a number of its degradation products. Nearly all (88 to 90%) strains used uric acid or allantoin as a sole nitrogen source; fewer (47 to 69%) used allantoate, urea, or possibly ureidoglycollate. Enzymatic activities of one representative isolate demonstrated the existence of a uric acid degradation pathway resembling that in other aerobic microorganisms.

Epidemiology of infection by nontuberculous Mycobacteria. III. Isolation of potentially pathogenic mycobacteria from aerosols

Nontuberculous mycobacteria (21 isolates), biochemically similar to those that are recovered from humans, were recovered from rainwater and from natural river waters and their aerosols in the area of Richmond, Virginia. Field experiments have confirmed the existence of a natural mechanism for the transfer of significant numbers of mycobacteria from water to air. These findings support the hypothesis that aerosolization of potentially pathogenic mycobacteria from waters of the southeastern United States may be a major pathway for human infection.