(442) CFTR Regulation of Naïve CD4+ T Cell Activity: Implications for Th2 Disease in Cystic Fibrosis

Background: Typical pulmonary manifestations of cystic fibrosis (CF) include chronic airway infection/inflammation, mucus accumulation, and airflow obstruction. Recent development of CFTR high efficiency modulator therapy (HEMT) has redefined morbidity and mortality for the disease, but emerging studies show persistence of inflammation despite increased CFTR function. Understanding immune cell dysfunction in cystic fibrosis will be necessary for HEMT adjunct therapies. Several lines of evidence suggests that the pro-inflammatory cytokine response to bacterial infection is exaggerated in CF, with more recent animal studies suggesting an innate priming of the adaptive immune response prior to infection. These observations taken together with a tendency toward asthma, dermatitis, and allergic reactions, suggest a role for the adaptive immune response in CF pathophysiology. The goals of this study were to: 1) identify in vitro Th2 specific cytokine changes in response CFTR loss, 2) investigate Th2-type responses in vivo using an Alternaria-inflammatory model in WT and CF mice, and 3) determine the inflammatory mechanisms for increased Th2 inflammation in CF disease by whole transcriptomic sequencing.

Methods: Naïve CD4+ T cells from Wild type (WT) and CFTR knockout mice (CF mice) on a C57BL/6 background were isolated from spleen and polarized to Th2 cells using plate-bound anti-CD3e and anti-CD28, in the presence of soluble anti-interferon gamma and IL-4 for 5 days. Cytokine measurements were made following restimulation. Comparative transcriptomic analysis from naïve CD4+ T and Th2 cells was performed. Both WT and CF mice were sensitized and challenged using Alternaria extract to elicit an adaptive immune response. Bronchoalveolar lavage (BAL), whole lung homogenate, and histopathological analysis was performed.

Results: In WT T cells, CFTR expression is tightly associated with T cell activation. Th2 cells from CF mice produce higher levels of IL-4, IL-5, and IL-13 in response to activation compared to WT Th2 cells. Loss of CFTR in naïve T cells leads to transcriptomic dysregulation including upregulation of 108 genes and downregulation of 18 genes. Following activation and polarization, loss of CFTR in Th2 cells leads to upregulation of 136 genes and downregulation of 56 genes. Comparative analysis demonstrates that increase in GATA-3 expression accounts for increased Th2 activity. In vivo, CF mice display increased inflammation by histology and increased Th2 cytokine production in response to Alternaria challenge compared to WT mice. Inhibition of the GATA-3 axis reduces Alternaria-induced inflammation in CF mice.

Conclusions: These findings demonstrate a role for CFTR in lymphocytes function and in part account for the increased allergic inflammation in CF. Efforts to develop CFTR modulator adjuncts for CF should encompass the adaptive immune system.

Acknowledgements: This work was supported by the Cystic Fibrosis Foundation (COOK20L0).

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