STING N153S triggers perivascular pulmonary inflammation, myeloid cell expansion, and T cell cytopenia independently of IRF3. (A) Expression of ISGs in STING N153S, STING knockout (Sting^−/−), and Trex1^−/− MEFs as well as STING N153S and Sting^−/− spleens. Each data point represents a unique ISG as fold increase compared with a WT littermate control. Data were assembled using ISG expression values from RNA-sequencing. (B) qRT-PCR analysis of ISGs in WT, STING N153S, Sting^−/− MEFs. mRNA expression is normalized to WT. (C) ISG expression in two healthy control (HC) and SAVI patient skin fibroblasts. Data represent a selection of ISGs assembled from RNA-sequencing. (D) qRT-PCR analysis of ISGs in skin fibroblasts. Data are from two independent experiments with two technical replicates per ISG, normalized to HC. (E) Hematoxylin and eosin images of lungs from Irf3^−/− and Irf3^−/− STING N153S mice (4–6 mo of age). Pulmonary vessels are indicated (v) with black arrows highlighting perivascular immune cell infiltration. Pulmonary vessels are indicated (v) with arrows. Bar, 100 µm. (F) Quantitation of perivascular lung lesions in STING N153S (n = 7) and Irf3^−/− N153S (n = 4) mice. Results in F represent the mean ± SEM of data collected and analyzed in two independent experiments. (G) ISG mRNA expression in Irf3^−/− and Irf3^−/− N153S MEFs normalized to gene expression in Irf3^−/− MEFs. Data represent the mean ± SEM from two independent experiments with n = 3 biological replicates per genotype. (H–J) Representative dot plots (H) and quantification (I and J) of splenic myeloid cell populations from WT, STING N153S, Irf3^−/−, and Irf3^−/− STING N153S mice. Data represent the mean of two independent experiments with n = 4 or 5 mice per genotype. (K and L) Percentage (K) and total number (L) of CD8⁺ splenocytes from WT, STING N153S, Irf3^−/−, and Irf3^−/− STING N153S mice. Data were pooled from two independent experiments with n = 4 or 5 mice per genotype. ns, not significant; *, P < 0.05; **, P < 0.005 by Mann–Whitney test.