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Cockroach sensitization mitigates allergic rhinoconjunctivitis in adults

Cockroach sensitization status is associated with mitigation of allergic rhinoconjunctivitis symptom severity in adults, according to Weijing He, MD, and colleagues.

“The pattern of allergen sensitization, as assessed by skin prick test reactivity, influences the symptom severity and immune responses of patients with allergic rhinoconjunctivitis,” He, of the Veterans Administration Center for Personalized Medicine of the South Texas Veterans Health Care System, and the department of medicine at the University of Texas Health Science Center at San Antonio, and colleagues wrote. “Balancing the sensitization status of patients with allergic rhinoconjunctivitis across the treatment vs. placebo arms in clinical trials might mitigate confounding.”

The hygiene hypothesis suggests childhood microbial exposure is a protective factor in allergic rhinoconjunctivitis. Therefore, cockroach sensitization may be a proxy for microbial exposure, according to study background.

The researchers sought to determine whether cockroach sensitization assayed by means of skin prick tests influenced allergic rhinoconjunctivitis symptom severity among 21 participants with house dust mite allergy in the natural setting and during repeated exposures of 3 hours per day to house dust mite allergen in an allergen challenge chamber.

From highest to lowest, results of total symptom scores indicated those with dust mite allergy and any pollen sensitization, but no cockroach sensitization, had greater symptom scores than those with all three sensitiztions. However, those with all three sensitizations had greater scores than those with dust mite allergy, but no pollen sensitizations or cockroach sensitization. Finally, those with dust mite allergy, but no pollen sensitizations or cockroach sensitization had greater scores than those with dust mite allergy and cockroach sensitization, but no pollen sensitizations.

Further, compared with those with dust mite allergy and any pollen sensitization, but no cockroach sensitization, those with all three sensitizations had rapidly resolved immune/inflammatory responses. For patients with any pollen sensitization, cockroach sensitization was associated with lower total symptom scores during pollen challenges and the pollination season, according to the researchers.

Results of aggregated analysis of all four studies assessing allergen challenge chamber indicated there was a 2.8-fold greater likelihood for a lower total symptom score among those with cockroach sensitization vs. those without cockroach sensitization (OR=2.78; 95% CI, 1.18-6.67).

“Our results underscore that the studies conducted within an allergen challenge chamber have utility for identifying pathogenic determinants that might underpin high versus low clinical responses to aeroallergens in a nonconfounded manner,” the researchers wrote. “Cockroach sensitization in polyallergic subjects influences allergic rhinoconjunctivitis disease severity in an allergen challenge chamber and natural settings. Lower allergic rhinoconjunctivitis symptom severity associated with cockroach sensitization might relate to lower T-cell activation in the periphery and a gene expression pattern that connotes rapid termination of immune/inflammatory pathways induced by aeroallergen exposure.”

Disclosure: The researchers report employment, consultant and investigator roles and shareholder status with Biogenics, Boehringer Ingelheim, Diagnostics Research Group, ICON Clinical Research and Merck.