In vitro responses of fibroblasts from patients with TBK1 deficiency after TLR3 dependent and independent stimuli. Homo sapiens

We report here two unrelated HSE patients carrying different heterozygous mutations (D50A and G159A) in TBK1, the gene encoding TANK-binding kinase 1, a kinase at the crossroads of multiple IFN-inducing signaling pathways. Both mutant TBK1 alleles are loss-of-function, but through different mechanisms: protein instability (D50A) or a loss of kinase activity (G159A). Both are also associated with an autosomal dominant (AD) trait, but by different mechanisms: haplotype-insufficiency (D50A) or negative dominance (G159A). A defect in poly(I:C)-induced TLR3 responses can be detected in fibroblasts heterozygous for G159A, but not for D50A TBK1. Overall design: Skin fibroblast cell lines were derived from healthy controls (n=3), patients with deficiencies for TBK1 (n=2), TLR3 (n=2), STAT1 (n=1) and cultured for 2 or 8 hours in the presence of IFNa (105 IU/ml), IL1b (20ng/ml), or poly I:C (25ug/ml) or left unstimulated for the same length of time.