Ronald J. Harbeck

Response to sublingual immunotherapy with grass pollen extract: Monotherapy versus combination in a multiallergen extract

BACKGROUNDnTo date, there have been no randomized, double-blind studies showing the effectiveness of sublingual immunotherapy with multiple allergens.nnnOBJECTIVEnThe purpose of this study was to examine whether the efficacy of sublingual immunotherapy (SLIT) with standardized timothy extract was reduced by combination with other allergen extracts.nnnMETHODSnA single-center, randomized, double-blind, placebo-controlled trial with SLIT was conducted. After an observational grass season, SLIT was administered for 10 months to 54 patients randomized to 1 of 3 treatment arms: placebo, timothy extract (19 microg Phl p 5 daily) as monotherapy, or the same dose of timothy extract plus 9 additional pollen extracts. Symptom and medication scores were collected and titrated nasal challenges, titrated skin prick tests, specific IgE, IgG4 and cytokines release by timothy-stimulated lymphocyte proliferation were performed.nnnRESULTSnPerhaps because of a very low grass pollen season in 2008, there were no significant differences in medication or symptom scores in either treatment group compared with placebo. Compared with placebo, in the timothy monotherapy group, thresholds for titrated nasal challenge and skin prick tests (P = .03 and P = .001, respectively), and serum-specific IgG4 levels (P = .005) significantly increased, and IFN- gamma levels decreased (P = .02), whereas in the multiallergen group, there was significant improvement only in the titrated skin prick tests (P = .04) which was less than in the monotherapy group. There were no significant differences between the 2 active groups in any outcome measure, and both active groups experienced more adverse events than placebo. There were no systemic reactions.nnnCONCLUSIONnImprovement in multiple relevant outcomes strongly suggests that SLIT with timothy extract alone was effective; however, the results for symptom and medication scores were not significant. The differences between multiple allergen SLIT and placebo only in skin sensitivity to timothy suggest a reduction in SLIT efficacy in this group. However, further studies are required to confirm these observations.

Effects of respiratory Mycoplasma pneumoniae infection on allergen-induced bronchial hyperresponsiveness and lung inflammation in mice.

ABSTRACT Airway mycoplasma infection may be associated with asthma pathophysiology. However, the direct effects of mycoplasma infection on asthma remain unknown. Using a murine allergic-asthma model, we evaluated the effects of different timing of airway Mycoplasma pneumoniae infection on bronchial hyperresponsiveness (BHR), lung inflammation, and the protein levels of Th1 (gamma interferon [IFN-γ]) and Th2 (interleukin 4 [IL-4]) cytokines in bronchoalveolar lavage fluid. When mycoplasma infection occurred 3 days before allergen (ovalbumin) sensitization and challenge, the infection reduced the BHR and inflammatory-cell influx into the lung. This was accompanied by a significant induction of Th1 responses (increased IFN-γ and decreased IL-4 production). Conversely, when mycoplasma infection occurred 2 days after allergen sensitization and challenge, the infection initially caused a temporary reduction of BHR and then increased BHR, lung inflammation, and IL-4 levels. Our data suggest that mycoplasma infection could modulate both physiological and immunological responses in the murine asthma model. Our animal models may also provide a new means to understand the role of infection in asthma pathogenesis and give evidence for the asthma hygiene hypothesis.

TLR2 Signaling Is Critical for Mycoplasma pneumoniae-Induced Airway Mucin Expression

Excessive airway mucin production contributes to airway obstruction in lung diseases such as asthma and chronic obstructive pulmonary disease. Respiratory infections, such as atypical bacterium Mycoplasma pneumoniae (Mp), have been proposed to worsen asthma and chronic obstructive pulmonary disease in part through increasing mucin. However, the molecular mechanisms involved in infection-induced airway mucin overexpression remain to be determined. TLRs have been recently shown to be a critical component in host innate immune response to infections. TLR2 signaling has been proposed to be involved in inflammatory cell activation by mycoplasma-derived lipoproteins. In this study, we show that TLR2 signaling is critical in Mp-induced airway mucin expression in mice and human lung epithelial cells. Respiratory Mp infection in BALB/c mice activated TLR2 signaling and increased airway mucin. A TLR2-neutralizing Ab significantly reduced mucin expression in Mp-infected BALB/c mice. Furthermore, Mp-induced airway mucin was abolished in TLR2 gene-deficient C57BL/6 mice. Additionally, Mp was shown to increase human lung A549 epithelial cell mucin expression, which was inhibited by the overexpression of a human TLR2 dominant-negative mutant. These results clearly demonstrate that respiratory Mp infection increases airway mucin expression, which is dependent on the activation of TLR2 signaling.

Toll-like Receptor 2 Down-regulation in Established Mouse Allergic Lungs Contributes to Decreased Mycoplasma Clearance

RATIONALEnRespiratory Mycoplasma pneumoniae (Mp) infection is involved in asthma pathobiology, but whether the established allergic airway inflammation compromises lung innate immunity and subsequently predisposes patients with asthma to Mp infection remains unknown.nnnOBJECTIVESnTo test whether the established allergic airway inflammation compromises host innate immunity (e.g., Toll-like receptor 2 [TLR2]) to hinder the elimination of Mp from the lungs.nnnMETHODSnWe used mouse models of ovalbumin (OVA)-induced allergic airway inflammation with an ensuing Mp infection, and cultures of mouse primary lung dendritic cells (DCs) and bone marrow-derived DCs.nnnMEASUREMENTS AND MAIN RESULTSnLung Mp clearance in allergic mice and TLR2 and IL-6 levels in lung cells, including DCs as well as cultured primary lung DCs and bone marrow-derived DCs, were assessed. The established OVA-induced allergic airway inflammation, or the prominent Th2 cytokines IL-4 and IL-13, inhibited TLR2 expression and IL-6 production in lung cells, including lung DCs, and eventually led to impaired host defense against Mp. Studies in IL-6 knockout mice indicated that IL-6 directly promoted Mp clearance from the lungs. IL-4- and IL-13-induced suppression of TLR2 was mediated by inhibiting nuclear factor-kappaB activation through signal transducer and activator of transcription 6 (STAT6) signaling pathway.nnnCONCLUSIONSnThe established OVA-induced allergic airway inflammation impairs TLR2 expression and host defense cytokine (e.g., IL-6) production, and subsequently delays lung bacterial clearance. This could offer novel therapeutic strategies to reinstate TLR2 activation by using TLR2 ligands and/or blocking IL-4 and IL-13 to ameliorate persisting respiratory bacterial infections in allergic lungs.

Human Surfactant Protein D (SP-D) Binds Mycoplasma pneumoniae by High Affinity Interactions with Lipids

Increasing evidence now identifies surfactant protein D (SP-D) as an important element of the innate immune system of the lung. In this study, we examined the interactions of rat and human SP-D with the human pathogen, Mycoplasma pneumoniae. Rat and human SP-D bound the organism with high affinity in a reaction that required Ca2+ and was inhibited by EGTA. Membranes derived from the organism bound the proteins in a similar manner, except the rat SP-D also exhibited a significant level of Ca2+-independent binding. Pretreatment of membranes with proteases did not alter the Ca2+-dependent SP-D binding of membranes by either protein. Mannose, glucose, maltose, and inositol, at millimolar concentrations, competed for human SP-D binding to the bacterial membrane. Lipids extracted from membranes and separated by two-dimensional thin layer chromatography bound human SP-D with high affinity in a Ca2+-dependent reaction. A tandem mutant of SP-D with E321Q and N323D substitutions, failed to bind M. pneumoniae lipids, directly implicating the carbohydrate recognition domain in the interaction. The interaction of rat and human SP-D with M. pneumoniae was unaffected by the presence of surfactant lipids and the hydrophobic surfactant proteins. These findings demonstrate that M. pneumoniae is likely to be recognized by SP-D in the alveolar environment and that primary determinants recognized on the organism are lipid components of the cell membrane.

Contribution of Ara h 2 to peanut-specific, immunoglobulin E-mediated, cell activation.

Background Ara h 2 is a potent peanut allergen but its contribution to the ability of a crude peanut extract (CPE) to cross‐link IgE and activate mast cells has not been rigorously evaluated.

Human phagocyte defect caused by a Rac2 mutation detected by means of neonatal screening for T-cell lymphopenia

in an IL2RG-deficient patient with SCID. A 7-month-old child presented with a retro-orbital EBV-negative diffuse large-cell B-lymphocyte non-Hodgkin lymphoma. Lymphoproliferative disorders developing in primary immunodeficiency are usually classifiable according to entities arising in immunocompetent individuals, often associated with EBV. In IL2RG-deficient SCID, tumors such as those described have not previously been reported. In each patient, presentation was extranodal and exhibited extensive necrosis. Both showed large HRS-resembling cell populations expressing CD30 and CD79a (and also CD20 and CD15 in case 2), in a background of histiocytes, fibroblasts, and lymphoid cells, predominantly B lymphocytes, the latter population showing focal plasma cell differentiation and light-chain restriction in case 1. There are several morphologic and phenotypic features resembling Hodgkin lymphoma, but extranodal presentation, extensive necrosis, and B-lymphocyte population with plasma cell differentiation (case 2) are inconsistent. The tumors described here share features with polymorphous posttransplant lymphoproliferative disease, in which extranodal presentation, necrosis, HRS-like cells, and B-lymphocyte proliferation with plasma cell differentiation are described. Similar lymphoproliferative disorders, usually EBV-associated, are seen in association with iatrogenic immunosuppression such as that occurring in methotrexate therapy. We conclude that Hodgkin-like polymorphous lymphoproliferative disorder is a rare presentation of lymphoid abnormalities in SCID.

Inhaled Fluticasone Propionate Reduces Concentration of Mycoplasma pneumoniae, Inflammation, and Bronchial Hyperresponsiveness in Lungs of Mice

BACKGROUNDnMycoplasma pneumoniae has been shown to induce airway inflammation and bronchial hyperresponsiveness (BHR) in mice. Inhaled corticosteroids are the mainstay of asthma treatment, but their effects on M. pneumoniae and associated airway inflammation and BHR are poorly understood.nnnMETHODSnFour groups of mice were studied to determine whether inhaled fluticasone propionate (FP) could attenuate airway inflammation and BHR by reducing or eliminating M. pneumoniae in lungs. The active group received aerosolized FP once daily for 5 days. Control mice received aerosolized sham solution plus M. pneumoniae, sham solution alone, or FP alone.nnnRESULTSnMice treated with sham solution or FP alone did not develop airway inflammation or BHR. Mice infected with M. pneumoniae (no FP) developed significant lung inflammation and BHR. FP treatment of infected mice reduced neutrophils in bronchoalveolar lavage fluid (BALF), lung inflammation, and BHR. Expression of Toll-like receptor 2 in lung tissue tended to be down-regulated (P=.18) by FP in infected mice. FP reduced M. pneumoniae by up to 20-fold in lung tissue but not in BALF.nnnCONCLUSIONnInhaled FP suppresses airway inflammation and BHR, which may be caused, in part, by its ability to reduce concentrations of M. pneumoniae in lung tissue.

Alpha beta T-lymphocyte depleted mice, a model for gamma delta T-lymphocyte functional studies.

Adult mice can be depleted of essentially all mature alpha beta T lymphocytes by chronic treatment with the framework-recognizing, pan-specific anti-TCR alpha beta mAb, H57-597. Similar findings have been reported in rats, gamma delta cell populations remain essentially unaltered in size and reactivity. Suppression of alpha beta T-cell development results in the loss of alloantigen reactivity and of B-cell help, suggesting that gamma delta and alpha beta populations differ in their functional capabilities. Indirect effects of the antibody treatment include quantitative changes in splenic B cells, as well as reduced sizes and weights of experimental animals. alpha beta-suppressed mice and rats may provide model systems for studies on gamma delta cell function in vivo.

Interaction Between Cigarette Smoke and Mycoplasma Infection: A Murine Model

Cigarette smoke has a major impact on health issues worldwide. Although genetics certainly is a factor in the sensitivity to cigarette smoke, other lung environmental factors, such as infection, potentially could interact with cigarette smoke to induce inflammatory changes associated with various diseases. Four groups of BALB/c mice (smoking only; smoking + M. pneumoniae infection; mycoplasma only; saline control) were studied for eight weeks to determine the interactive outcomes of inflammation and structural changes in the smoking plus mycoplasma group. This group did have significantly higher amounts of neutrophil degranulation in the outer airway wall area (smooth muscle to alveolar attachments) (p = 0.03) and mRNA expression of matrix metalloproteinase-9 (p = 0.045). Although there was not a significant difference in alveolar tissue elastin between the groups, the smoking plus mycoplasma group had a level approximately 20% below the other groups. Even in this relatively short duration study, it appears that an infectious process can interact with cigarette smoke to produce a destructive type of inflammatory response (activated neutrophils and metalloproteinase-9) seen in the outer airway wall area.