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Use of Biomarker Based on Human Basophil Syk Expression to Predict the Clinical Efficacy of Omalizumab Treatment in Allergic Asthmatics
Abstracts AB167
J ALLERGY CLIN IMMUNOL VOLUME 139, NUMBER 2
N-Glycan in Cockroach Allergen Regulates Human Basophil Function
Danh C. Do, PhD1, Shuang Yang, PhD2, Robert G. Hamilton, PhD, DABMLI FAAAAI1, John T. Schroeder, PhD1, Hui Zhang, PhD2, and Peisong Gao, MD, PhD1; 1The Johns Hopkins Asthma and Allergy Center, Baltimore, MD, 2The Johns Hopkins Pathology-Clinical Chemistry, Baltimore, MD. RATIONALE: Cockroach exposure has been linked to cockroach sensitization and increased risk of asthma. Cockroach allergen (CRE) can induce allergic responses and lung inflammation, however, little is known about the major components and the mechanisms underlying CREinduced allergy and asthma. We sought to examine the role of glycan associated cockroach allergen in regulating human basophil function. METHODS: Glycans from naturally purified cockroach allergen Bla g 2 were characterized by MALDI-TOF. Binding of CRE to serum IgE from cockroach allergic subjects was determined by solid-phase binding immunoassays. Role of cockroach associated glycan in histamine release and IL-4 production from human basophils was examined. Expression of C-type lectin receptors and their role in mediating glycan-uptake in the basophil was also investigated. RESULTS: CRE contains multiple glycosylated proteins. Among them, the major glyco-allergen Bla g 2 contain complex- and hybrid-type with core fucose modifications. Deglycosylated Bla g 2 showed reduced the binding to Bla g 2-specific-IgE and decreased histamine release from human basophils. In contrast, N-glycan derived from Bla g 2 significantly inhibited histamine release induced by IgE anti-cockroach containing sera from cockroach allergic subjects and IL-4 production. Human basophil expresses DC-SIGN and DCIR, but not MRC1 and dectin1. DCIR, but not DC-SIGN, neutralizing antibody significantly inhibited Bla g 2 uptake by human basophils. CONCLUSIONS: These observations support a critical but previously unrecognized role of glycan in allergen-induced allergic responses, and DCIR may mediate the regulation of allergen glycan on basophil function.
534
Use of Biomarker Based on Human Basophil Syk Expression to Predict the Clinical Efficacy of Omalizumab Treatment in Allergic Asthmatics
Donald MacGlashan, MD, PhD1, and Sarbjit Singh Saini, MD, FAAAAI2; 1JHAAC, Baltimore, MD, 2Johns Hopkins Allergy Asthma Center, Baltimore, MD. RATIONALE: Treatment with omalizumab results in the increased sensitivity of basophils to IgE-mediated stimulation, likely due to an increase in syk expression in basophils. Studies in patients with peanut allergy suggested that the increased sensitivity works in opposition to the therapeutic benefits of reduced free IgE. This study examined whether a priori knowledge of syk expression or maximum IgE-mediated histamine release, which is related to syk expression, would provide a predictor of the efficacy of omalizumab in patients with allergic asthma. METHODS: Adult asthma patients were enrolled and treated with omalizumab for 16 weeks using FDA-approved dosing criteria. Blood basophils were examined for syk expression, IgE-mediated histamine release and changes in these two parameters before and after treatment. Clinical response was measured via a physician’s assessment score (PAS, 1-5 score range, 1 5 minimal symptoms) and a final assessment of success. Basophil studies and clinical evaluations were maintained by separate groups. _4). For this RESULTS: Ten patients satisfied entry criteria (PAS scores of > group, all four metrics, starting syk, changes in syk, starting and changes in histamine release showed a positive chi-square association (p-values ranged 0.0098 to 0.038) with the success of treatment. CONCLUSIONS: This study suggests that changes in syk expression and therefore the functionality of human basophils may provide a predictor of successful treatment of asthmatics with omalizumab. Since the change in syk expression is related to starting syk, it is possible that baseline basophil
syk or histamine release might be a bio-marker of successful treatment with omalizumab.
535
An Analysis of Potential Associations Between Delivery Mode and Dog-Keeping to Basophil FcER1 and Activation Marker Expression During Infancy
D. Orandi1, S. Havstad2, A. Sitarik1, K. Bobbitt1, K. Jones2, A. Levin2, N. Lukacs3, S. V. Lynch4, G. Wegienka1, K. Woodcroft1, D. Ownby5, C. Johnson6, and E. Zoratti7; 1Henry Ford Health System, Detroit, MI, 2Henry Ford Health Systems, Detroit, MI, 3University of Michigan Medical School, Ann Arbor, MI, 4UCSF, San Francisco, CA, 5Medical Center of Augusta, Saint Marys, GA, 6University of Michigan, Livonia, MI, 7Henry Ford Hospital, Detroit, MI. RATIONALE: Early-life exposures, including dog-keeping and vaginal delivery, are associated with lower rates of childhood allergy. The underlying immune mechanism(s) are unknown. Basophils are innate immune cells capable of promoting Th2 polarization and allergy development. We explored associations of these exposures with basophil FcεR1 and activation marker expression during the first 6 months of life. METHODS: Basophil-lineage cells (low side scatter/Class II2/CD123+ from the enriched granulocyte fraction) FcεR1, CD63 and CD203c were identified by flow cytometry in cord blood and at age 6 months in the Microbes, Allergy, Asthma and Pets birth cohort. Concomitant total IgE levels were determined. Dog-keeping during pregnancy and delivery mode data was collected prospectively. Analysis included non-parametric testing using Kruskal-Wallis and Wilcoxon rank sum comparisons. RESULTS: No associations between dog-keeping (any vs. none) and basophil marker expression were apparent. However, children from homes with >1 dog had lower proportions of basophils expressing CD63 at 6 months (median511.9%, n518) than those with 0 or 1 dog (median521.3%, n533; median530.7%, n526, respectively; p50.045). A trend for lower percentage FcεR1 expression with >1 dog was noted (p50.096). Vaginal delivery was associated with proportionally fewer basophils expressing FcεR1 versus c-section in cord blood only (median513.7%, n580; median550%, n516, respectively; p50.031). Cord and 6 month IgE levels did not correlate with basophil marker expression. CONCLUSIONS: Early-life exposure to multiple dogs is associated with lower proportions of basophils expressing CD63 at 6 months. Natural parturition is associated with lower proportions of basophils expressing FcεR1 in cord blood. These associations may relate to lowered allergy risk.
SUNDAY
533
J ALLERGY CLIN IMMUNOL VOLUME 139, NUMBER 2
N-Glycan in Cockroach Allergen Regulates Human Basophil Function
Danh C. Do, PhD1, Shuang Yang, PhD2, Robert G. Hamilton, PhD, DABMLI FAAAAI1, John T. Schroeder, PhD1, Hui Zhang, PhD2, and Peisong Gao, MD, PhD1; 1The Johns Hopkins Asthma and Allergy Center, Baltimore, MD, 2The Johns Hopkins Pathology-Clinical Chemistry, Baltimore, MD. RATIONALE: Cockroach exposure has been linked to cockroach sensitization and increased risk of asthma. Cockroach allergen (CRE) can induce allergic responses and lung inflammation, however, little is known about the major components and the mechanisms underlying CREinduced allergy and asthma. We sought to examine the role of glycan associated cockroach allergen in regulating human basophil function. METHODS: Glycans from naturally purified cockroach allergen Bla g 2 were characterized by MALDI-TOF. Binding of CRE to serum IgE from cockroach allergic subjects was determined by solid-phase binding immunoassays. Role of cockroach associated glycan in histamine release and IL-4 production from human basophils was examined. Expression of C-type lectin receptors and their role in mediating glycan-uptake in the basophil was also investigated. RESULTS: CRE contains multiple glycosylated proteins. Among them, the major glyco-allergen Bla g 2 contain complex- and hybrid-type with core fucose modifications. Deglycosylated Bla g 2 showed reduced the binding to Bla g 2-specific-IgE and decreased histamine release from human basophils. In contrast, N-glycan derived from Bla g 2 significantly inhibited histamine release induced by IgE anti-cockroach containing sera from cockroach allergic subjects and IL-4 production. Human basophil expresses DC-SIGN and DCIR, but not MRC1 and dectin1. DCIR, but not DC-SIGN, neutralizing antibody significantly inhibited Bla g 2 uptake by human basophils. CONCLUSIONS: These observations support a critical but previously unrecognized role of glycan in allergen-induced allergic responses, and DCIR may mediate the regulation of allergen glycan on basophil function.
534
Use of Biomarker Based on Human Basophil Syk Expression to Predict the Clinical Efficacy of Omalizumab Treatment in Allergic Asthmatics
Donald MacGlashan, MD, PhD1, and Sarbjit Singh Saini, MD, FAAAAI2; 1JHAAC, Baltimore, MD, 2Johns Hopkins Allergy Asthma Center, Baltimore, MD. RATIONALE: Treatment with omalizumab results in the increased sensitivity of basophils to IgE-mediated stimulation, likely due to an increase in syk expression in basophils. Studies in patients with peanut allergy suggested that the increased sensitivity works in opposition to the therapeutic benefits of reduced free IgE. This study examined whether a priori knowledge of syk expression or maximum IgE-mediated histamine release, which is related to syk expression, would provide a predictor of the efficacy of omalizumab in patients with allergic asthma. METHODS: Adult asthma patients were enrolled and treated with omalizumab for 16 weeks using FDA-approved dosing criteria. Blood basophils were examined for syk expression, IgE-mediated histamine release and changes in these two parameters before and after treatment. Clinical response was measured via a physician’s assessment score (PAS, 1-5 score range, 1 5 minimal symptoms) and a final assessment of success. Basophil studies and clinical evaluations were maintained by separate groups. _4). For this RESULTS: Ten patients satisfied entry criteria (PAS scores of > group, all four metrics, starting syk, changes in syk, starting and changes in histamine release showed a positive chi-square association (p-values ranged 0.0098 to 0.038) with the success of treatment. CONCLUSIONS: This study suggests that changes in syk expression and therefore the functionality of human basophils may provide a predictor of successful treatment of asthmatics with omalizumab. Since the change in syk expression is related to starting syk, it is possible that baseline basophil
syk or histamine release might be a bio-marker of successful treatment with omalizumab.
535
An Analysis of Potential Associations Between Delivery Mode and Dog-Keeping to Basophil FcER1 and Activation Marker Expression During Infancy
D. Orandi1, S. Havstad2, A. Sitarik1, K. Bobbitt1, K. Jones2, A. Levin2, N. Lukacs3, S. V. Lynch4, G. Wegienka1, K. Woodcroft1, D. Ownby5, C. Johnson6, and E. Zoratti7; 1Henry Ford Health System, Detroit, MI, 2Henry Ford Health Systems, Detroit, MI, 3University of Michigan Medical School, Ann Arbor, MI, 4UCSF, San Francisco, CA, 5Medical Center of Augusta, Saint Marys, GA, 6University of Michigan, Livonia, MI, 7Henry Ford Hospital, Detroit, MI. RATIONALE: Early-life exposures, including dog-keeping and vaginal delivery, are associated with lower rates of childhood allergy. The underlying immune mechanism(s) are unknown. Basophils are innate immune cells capable of promoting Th2 polarization and allergy development. We explored associations of these exposures with basophil FcεR1 and activation marker expression during the first 6 months of life. METHODS: Basophil-lineage cells (low side scatter/Class II2/CD123+ from the enriched granulocyte fraction) FcεR1, CD63 and CD203c were identified by flow cytometry in cord blood and at age 6 months in the Microbes, Allergy, Asthma and Pets birth cohort. Concomitant total IgE levels were determined. Dog-keeping during pregnancy and delivery mode data was collected prospectively. Analysis included non-parametric testing using Kruskal-Wallis and Wilcoxon rank sum comparisons. RESULTS: No associations between dog-keeping (any vs. none) and basophil marker expression were apparent. However, children from homes with >1 dog had lower proportions of basophils expressing CD63 at 6 months (median511.9%, n518) than those with 0 or 1 dog (median521.3%, n533; median530.7%, n526, respectively; p50.045). A trend for lower percentage FcεR1 expression with >1 dog was noted (p50.096). Vaginal delivery was associated with proportionally fewer basophils expressing FcεR1 versus c-section in cord blood only (median513.7%, n580; median550%, n516, respectively; p50.031). Cord and 6 month IgE levels did not correlate with basophil marker expression. CONCLUSIONS: Early-life exposure to multiple dogs is associated with lower proportions of basophils expressing CD63 at 6 months. Natural parturition is associated with lower proportions of basophils expressing FcεR1 in cord blood. These associations may relate to lowered allergy risk.
SUNDAY
533