Immune Profiles in CF Fungal Infection

While bacteria are predominant agents in CF lung disease, fungi are often isolated in both sputum and bronchoalveolar lavage fluid (BAL), yet their role in CF is not fully understood. Fungal infection in CF has a wide spectrum of presentations, varying from transient detection to persistent infection, acute fungal bronchitis with resulting pulmonary exacerbation, sensitization to fungal allergens, and allergic bronchopulmonary aspergillosis (ABPA). While there are clinical guidelines for the diagnosis and treatment of ABPA in patients with CF, there are few guidelines and recommendations regarding monitoring, clinical care, and antifungal treatment in the various presentations of CF fungal disease; further, the clinical impact of fungi without ABPA is poorly understood. While inflammation in CF is classically considered a neutrophil and macrophage driven process (Th1), eosinophils and allergic cytokines (Th2) have been shown to be elevated in the presence of fungal disease in both clinical and animal CF studies. Studies have also shown decreased lung function (e.g. percent predicted forced expiratory volume in one second, ppFEV1) in individuals with frequent fungal detection in their sputum, and associations with Pseudomonas infection and use of antimicrobials. Adults with CF are also more prone to fungal sensitization when compared to non-CF patients as well as having higher rates of allergic rhinitis and atopy. In a retrospective study performed at our center, we found that children with intermittent or chronic fungal infections experienced more rapid decline in lung function compared to those without fungal infections regardless of ABPA status (see preliminary data). Understanding whether fungal infections are driven by an allergic (Th2) inflammatory process may alter treatment approaches by utilizing steroids and antifungal therapies more readily in patients with fungal infection to combat lung function decline. Limited studies have investigated the frequency of allergic sensitization to fungal pathogens in individuals with CF, the frequency of allergic sensitization in the pediatric CF population in general, and the unique inflammatory profiles and phenotypes of CF fungal infections, both in the sputum and the serum.

Hypothesis: We hypothesize that children with CF and fungal infections without ABPA will have elevated allergic inflammatory profiles and increased sensitization to fungal elements compared to those without fungal infection.

Specific Aim 1: Compare Th2 inflammation in patients with and without fungal infections in patients with CF and to those with ABPA.

• Approach: We will obtain serum and sputum samples from 25 patients with either (1) fungal infection without ABPA, n=10 (defined as ≥ two positive fungal cultures in prior 18 months), (2) no fungal infection, n=10, and (3) ABPA, n=5, and measure specific sputum and serum cytokine measurements to evaluate Th2 and Th1 inflammatory pathways.
• Biomarkers measured: Eosinophilic cationic protein (ECP), Interleukin-4 (IL4), Interleukin-5 (IL5), Interleukin-10 (IL10), Interleukin-13 (IL13), and eosinophil count in both serum and sputum.
• Expected outcome: Individuals with fungal infection without APBA will have elevated Th2 markers of inflammation compared to those with no fungal infection. We will also compare to those with ABPA as a separate control group. We will also measure Th1 markers to be used as a reference to previously established inflammatory profiles seen in CF, seeing if those with fungal disease deviate towards a more Th2 driven process.

Specific Aim 2: Investigate allergic sensitization to fungal elements in patients with CF fungal infection without ABPA compared to those without fungal infection and to those with ABPA.