STAT3-dependent Regulation of CFTR and Ciliogenesis Is Essential for Mucociliary Clearance and Innate Airway Defense in Hyper-IgE Syndrome.

Rationale: Hyper IgE syndrome (STAT3-HIES), also known as Job's syndrome, is a rare immunodeficiency disease typically caused by dominant-negative STAT3 mutations. STAT3-HIES is characterized by chronic pulmonary infection and inflammation, suggesting impaired innate host defense.

Objectives: To identify airway epithelial host defense defects caused by STAT3 mutations that, together with immune dysfunction, contribute to recurrent pulmonary infections in STAT3-HIES.

Methods: STAT3-HIES sputum was analyzed for biochemical and biophysical properties. STAT3-HIES excised lungs were harvested for histology; and bronchial brush samples were collected for RNA sequencing and in vitro culture. A STAT3-HIES-specific R382W mutation, expressed via lentivirus, and STAT3 knockout (CRISPR/Cas9), were studied in normal human bronchial epithelial cells under basal or inflammatory (IL1β)-stimulated conditions. Effects of STAT3 deficiency on transcriptomics, epithelial ion channel, secretory, antimicrobial, and ciliary functions were assessed.

Measurements And Main Results: STAT3-HIES sputum showed increased mucus concentration and viscoelasticity. STAT3-HIES excised lungs exhibited mucus obstruction and elevated IL1β expression. STAT3 mutations reduced CFTR mRNA and protein levels, impaired CFTR-dependent fluid and mucin secretion, suppressed antimicrobial peptide, cytokine, and chemokine expression, and acidified airway surface liquid at baseline and post-IL1β exposure. Notably, mutant STAT3 suppressed IL1R1 expression. Furthermore, STAT3 mutations impaired multiciliogenesis by blocking commitment to ciliated cell lineages through inhibition of HES6, leading to defective mucociliary transport. Administration of a γ-secretase inhibitor restored HES6 expression, improved ciliogenesis in STAT3 R382W mutant cells.

Conclusions: STAT3 dysfunction leads to multi-component defects in airway epithelial innate defense, which, in conjunction with immune deficiency, contributes to chronic pulmonary infection in STAT3-HIES.