Mutations in STAT3 and diagnostic guidelines for hyper-IgE syndrome

Abstract

Background: The hyper-IgE syndrome (HIES) is a primary immunodeficiency characterized by infections of the lung and skin, elevated serum IgE, and involvement of the soft and bony tissues. Recently, HIES has been associated with heterozygous dominant-negative mutations in the signal transducer and activator of transcription 3 (STAT3) and severe reductions of T(H)17 cells.

Objective: To determine whether there is a correlation between the genotype and the phenotype of patients with HIES and to establish diagnostic criteria to distinguish between STAT3 mutated and STAT3 wild-type patients.

Methods: We collected clinical data, determined T(H)17 cell numbers, and sequenced STAT3 in 100 patients with a strong clinical suspicion of HIES and serum IgE >1000 IU/mL. We explored diagnostic criteria by using a machine-learning approach to identify which features best predict a STAT3 mutation.

Results: In 64 patients, we identified 31 different STAT3 mutations, 18 of which were novel. These included mutations at splice sites and outside the previously implicated DNA-binding and Src homology 2 domains. A combination of 5 clinical features predicted STAT3 mutations with 85% accuracy. T(H)17 cells were profoundly reduced in patients harboring STAT3 mutations, whereas 10 of 13 patients without mutations had low (<1%) T(H)17 cells but were distinct by markedly reduced IFN-gamma-producing CD4(+)T cells.

Conclusion: We propose the following diagnostic guidelines for STAT3-deficient HIES. Possible: IgE >1000IU/mL plus a weighted score of clinical features >30 based on recurrent pneumonia, newborn rash, pathologic bone fractures, characteristic face, and high palate. Probable: These characteristics plus lack of T(H)17 cells or a family history for definitive HIES. Definitive: These characteristics plus a dominant-negative heterozygous mutation in STAT3.

Figure 1

Inhibition of TNF-α release in LPS-activated macrophages by IL-10. Macrophages of nine STAT3-mutated patients, eight of whom had novel mutations, one STAT3 wt patient and eleven healthy controls were pre-treated with IL-10 and then stimulated with LPS. Supernatants were examined for the presence of TNF-α. In order to ensure better comparability of data from different healthy donors, the impact of IL-10 on TNF-α release is shown as percentage of maximum TNF-α release upon LPS stimulation.

Figure 2

Percentage of IL-17 (A) and IFN-γ (B) expressing CD4⁺ memory T cells, determined by intracellular cytokine expression after overnight stimulation with Staphylococcus enterotoxin B (SEB). Each symbol represents the value from an individual donor or patient. Statistical significance was determined with a Wilcoxon rank-sum test. P-values are two-sided. Median values are shown as horizontal bars.

Figure 3

Schematic structure of STAT3. Every black dot represents one patient carrying the mutation. Patients that carry STAT3 mutations and that were described in previous publication are shown in the upper part of the figure. ,, – The 64 patients identified in this study who had STAT3 mutations are shown in the lower part. The patient carrying a splice site mutation after exon 22 is shown as having DNA sequence change as the effect on the protein is not known. p.?, unknown effect on protein level