Purpose: The primary objective of this study is to examine the effectiveness of anakinra as a rescue treatment for allergic airway inflammation. Utilizing an inhaled allergen challenge model, the investigators will determine the effectiveness of a single 1 mg/kg dose of anakinra administered after inhaled allergen challenge for mitigating features of airway inflammation. Participants: 12 mild allergic asthmatics sensitized to Dermatophagoides farinae (D. farinae) Procedures (methods): Eligible subjects will participate in a double blind cross-over study. Following randomization to the placebo or anakinra treatment group, subjects will undergo inhalation of D. farinae, and their early and late phase asthmatic responses will be measured. Subjects will undergo induced sputum sampling, methacholine challenge, and mucociliary clearance measures. After completion of period 1, subjects will cross over to the alternate study arm.
Asthma is an increasingly common chronic illness with higher rates of hospitalization for exacerbation than many other chronic conditions. In 2009, total asthma costs in the U.S. were estimated at $56 billion per year, and over half the overall asthma-related costs were attributed to inpatient hospitalization. Allergen exposure and viral infection are among the most common triggers for asthma exacerbations. Exacerbations of allergic asthma are characterized by an early phase response (EPR), mediated by release of preformed mediators like histamine from mast cells, and a late phase response (LPR) 3-7 hours later mediated by chemokines and cytokines, including IL-1β, that attract leukocytes such as neutrophils and eosinophils to the airways, increase mucus production, trigger airway smooth muscle contraction, and result in airway constriction and airway hyper-reactivity (AHR). The LPR is thought to be predominantly responsible for the symptoms associated with acute exacerbations of allergic asthma. While corticosteroids are considered a mainstay of treatment for asthma exacerbation regardless of the trigger, there are limitations to their effectiveness in the acute setting including the initial lag period of 4-6 hours or more before therapeutic effect and the concern for broad immune suppression. Corticosteroids are often ineffective in treating the neutrophilic component of airway inflammation seen with viral infection and allergen-induced airway inflammation. Finally, mucus plugging is a known hallmark of severe and fatal asthma, yet there is a notable lack of effective mucolytic treatments for asthma. Time to therapeutic benefit is key in preventing patient morbidity and mortality. Currently there is an urgent need for anti-inflammatory treatments that work quickly and effectively in acute asthma exacerbations. The investigators propose that IL-1 blockade can achieve these ends and perhaps complement corticosteroid actions. Anakinra is an FDA-approved recombinant form of human IL-1 receptor antagonist (IL-1RA), a natural anti-inflammatory cytokine that competes with agonist binding to the IL-1 receptor, suppressing IL-1β and IL-1a signaling. IL-1 signaling mediates key features of viral- and allergen-induced airway inflammation. Previous studies in animal and in vitro models demonstrate that IL-1 signaling can directly impact three aspects of an airway inflammatory response: granulocyte (neutrophil/eosinophil) recruitment; non-specific and allergen-specific airway reactivity; and mucin production. Numerous IL-1 blocking agents are FDA-approved for conditions where the IL-1β pathway predominates disease pathophysiology, such as in systemic juvenile idiopathic arthritis and the cryopyrin-associated periodic syndromes. Anakinra is an ideal candidate to test as a rescue treatment for acute asthma exacerbation due to its fast onset of action (reaching peak concentrations in 3-7 hours), and a short 4-6 hour half-life. A single 1mg/kg dose (up to 100mg) of anakinra or placebo will be administered at the onset of the EPR to model anakinra use in an emergency care setting. This dose was chosen because it is the current FDA-approved dose for rheumatoid arthritis (RA). Notably, the investigators have previously demonstrated that a 1 mg/kg dose resulted in significant reduction in airway granulocyte recruitment following lipopolysaccharide (LPS) challenge in a study of healthy volunteers. The investigators' objective is to determine if a single 1 mg/kg dose of Anakinra can mitigate key features of asthma exacerbations, namely AHR, airway constriction, airway inflammation, and mucous secretion/clearance.
A single 1mg/kg subcutaneous injection (up to 100mg) of anakinra will be administered at the onset of the EPR, directly after the allergen challenge, to model anakinra use in an emergency care setting.
A single dose of matching placebo will be administered at the onset of the EPR, directly after the allergen challenge, to model anakinra use in an emergency care setting.
Standardized house dust mite Dermatophagoides farinae (D. farinae) allergen extract at 30,000 allergen units (AU)/mL for inhalation (provided by Greer Laboratories, Lenoir, NC).
Maximum % FEV1 drop from Baseline during LPR period
The principal endpoint will be maximal % drop in Forced Expiratory Volume in 1 second (FEV1) from baseline during the LPR period (3-10 hours). The FEV1 following saline and prior to the first dose of antigen during the inhaled allergen challenge will be considered the baseline value. Declines in FEV1 will be measured as a % drop from the baseline. A provocative dose causing a 20% fall FEV1 (PD20) is determined during the allergen challenge.
Time frame: Baseline and 3-10 hours following PD20
Area under the curve (AUC) % drop in FEV1 in the LPR
The FEV1 following saline and prior to the first dose of antigen during the inhaled allergen challenge will be considered the baseline value from which the % drop in FEV1 will be determined.
Time frame: Baseline and 3-10 hours following PD20
Change in Methacholine reactivity, as measured by the concentration of methacholine resulting in a 20% drop in FEV1 (PC20)
Participants will undergo a methacholine challenge to assess airway hyper-responsiveness at baseline. Change in methacholine reactivity, as measured by the PC20, from baseline to 24 hours after the allergen challenge will be determined.
Time frame: Baseline and 24 hours post allergen challenge
Fractional exhaled Nitric Oxide (FeNO) as an exploratory biomarker
FeNO is being investigated as a non-invasive airway inflammation marker. FeNO is measured in ppb with a chemoluminescence analyzer before the saline and prior to the first dose of antigen during the inhaled allergen challenge and at 24 hours post the allergen challenge.
Time frame: Baseline and 24 hours post allergen challenge
Change in % eosinophils in induced sputum
An induced sputum sample will be processed and counted to provide the % change in eosinophils between the two time points.
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Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
DOUBLE
Time frame: Baseline and 24 hours post allergen challenge
Change in % neutrophils in induced sputum
An induced sputum sample will be processed and counted to provide the % change in neutrophils between the two time points.
Time frame: Baseline and 24 hours post allergen challenge
Change in eosinophils per mg of induced sputum
An induced sputum sample will be processed and counted to provide the eosinophils per mg change between the two time points.
Time frame: Baseline and 24 hours post allergen challenge
Change in neutrophils per mg of induced sputum
An induced sputum sample will be processed and counted to provide the neutrophils per mg change between the two time points.
Time frame: Baseline and 24 hours post allergen challenge
Change in sputum levels of major respiratory mucin MUC5AC (mucin 5AC, oligomeric mucus/gel-forming)
An induced sputum sample will be processed and analyzed for the amount of protein MUC5AC between the two time points.
Time frame: Baseline and 24 hours post allergen challenge
Change in sputum levels of major respiratory mucin MUC5B (mucin 5B, oligomeric mucus/gel-forming)
An induced sputum sample will be processed and analyzed for the amount of protein MUC5B between the two time points.
Time frame: Baseline and 24 hours post allergen challenge
Change in Mucociliary clearance (MCC)
The change in MCC will be measured as % tracheobronchial retention of radiolabeled particles in the airways.
Time frame: 4 hours post allergen challenge
Central (C) vs. peripheral (P) deposition ratio (C/P)
C/P is a reflection of deposition in the central airways during MCC.
Time frame: 4 hours post allergen challenge