Spontaneous Gastrointestinal Perforations in STAT3-Deficient Hyper-IgE Syndrome

Tocilizumab effectively reduces flares of hyperimmunoglobulin D syndrome in children: Three cases in China

Hyperimmunoglobulin D syndrome (HIDS) is a rare but severe autoinflammatory disease with a poor prognosis if not diagnosed and treated early. Here, we report three cases of HIDS in children with typical clinical manifestations and a clear genetic diagnosis. Patient 1 experienced recurrent fever flares with a maculo-papular skin rash. Patient 2 presented with periodic fever, cholestasis, lymphadenopathy, aphthous stomatitis, arthralgia, and abdominal pain and underwent surgery for intestinal obstruction. Patient 3, a sibling of patient 2, presented with periodic fever and underwent a surgical procedure for intussusception. All three patients were administered interleukin (IL)-6 receptor antagonist (tocilizumab). The results showed that tocilizumab effectively reduced inflammatory flares. Early diagnosis and tocilizumab treatment are effective at improving the prognosis of HIDS patients.

Dysregulated Airway Host Defense in Hyper IgE Syndrome due to STAT3 Mutations

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 syndrome is characterized by chronic pulmonary infection and inflammation, suggesting impairment of pulmonary innate host defense.

Objectives

To identify airway epithelial host defense defects consequent to STAT3 mutations that, in addition to reported mutant STAT3 immunologic abnormalities, produce pulmonary infection.

Methods

STAT3-HIES sputum was evaluated for biochemical/biophysical properties. STAT3-HIES excised lungs were harvested for histology; bronchial brush samples were collected for RNA sequencing and in vitro culture. A STAT3-HIES-specific mutation (R382W), expressed by lentiviruses, and a STAT3 knockout, generated by CRISPR/Cas9, were maintained in normal human bronchial epithelia under basal or inflammatory (IL1β) conditions. Effects of STAT3 deficiency on transcriptomics, and epithelial ion channel, secretory, antimicrobial, and ciliary functions were assessed.

Measurements and Main Results

Mucus concentrations and viscoelasticity were increased in STAT3-HIES sputum. STAT3-HIES excised lungs exhibited mucus obstruction and elevated IL1β expression. STAT3 deficiency impaired CFTR-dependent fluid and mucin secretion, inhibited expression of antimicrobial peptides, cytokines, and chemokines, and acidified airway surface liquid at baseline and post-IL1β exposure in vitro. Notably, mutant STAT3 suppressed IL1R1 expression. STAT3 mutations also inhibited ciliogenesis in vivo and impaired mucociliary transport in vitro, a process mediated via HES6 suppression. Administration of a γ-secretase inhibitor increased HES6 expression and improved ciliogenesis in STAT3 R382W mutant cells.

Conclusions

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

Ex vivo effect of JAK inhibition on JAK-STAT1 pathway hyperactivation in patients with dominant-negative STAT3 mutations

PURPOSE

STAT1 gain-of-function (GOF) and dominant-negative (DN) STAT3 syndromes share clinical manifestations including infectious and inflammatory manifestations. Targeted treatment with Janus-kinase (JAK) inhibitors shows promising results in treating STAT1 GOF-associated symptoms while management of DN STAT3 patients has been largely supportive. We here assessed the impact of ruxolitinib on the JAK-STAT1/3 pathway in DN STAT3 patients' cells.

METHODS

Using flow cytometry, immunoblot, qPCR, and ELISA techniques, we examined the levels of basal STAT1 and phosphorylated STAT1 (pSTAT1) of cells obtained from DN STAT3, STAT1 GOF patients, and healthy donors following stimulation with type I/II interferons (IFNs) or interleukin (IL)-6. We also describe the impact of ruxolitinib on cytokine-induced STAT1 signaling in these patients.

RESULTS

DN STAT3 and STAT1 GOF resulted in a similar phenotype characterized by increased STAT1 and pSTAT1 levels in response to IFNα (CD3⁺ cells) and IFNγ (CD14⁺ monocytes). STAT1-downstream gene expression and C-X-C motif chemokine 10 secretion were higher in most DN STAT3 patients upon stimulation compared to healthy controls. Ex vivo treatment with the JAK1/2-inhibitor ruxolitinib reduced cytokine responsiveness and normalized STAT1 phosphorylation in DN STAT3 and STAT1 GOF patient' cells. In addition, ex vivo treatment was effective in modulating STAT1 downstream signaling in DN STAT3 patients.

CONCLUSION

In the absence of effective targeted treatment options for AD-HIES at present, modulation of the JAK/STAT1 pathway with JAK inhibitors may be further explored particularly in those AD-HIES patients with autoimmune and/or autoinflammatory manifestations.

Inborn errors of IL-6 family cytokine responses

The IL-6 family of cytokines mediates functions in host protective immunity, development of multiple organs, tissue regeneration and metabolism. Inborn errors in cytokines or cytokine receptor units highlight specific roles for IL-6, IL-11, LIF, OSM, and CLC signaling whereas incomplete loss-of-function variants in the common receptor chain GP130 encoded by IL6ST or the transcription factor STAT3, as well as genes that affect either GP130 glycosylation (PGM3) or STAT3 transcriptional control (ZNF341) lead to complex phenotypes including features of hyper-IgE syndrome. Gain-of-function variants in the GP130-STAT3 signaling pathway cause immune dysregulation disorders. Insights into IL-6 family cytokine signaling inform on therapeutic application in immune-mediated disorders and potential side effects such as infection susceptibility.

STAT3 Hyper-IgE Syndrome-an Update and Unanswered Questions

The hyper-IgE syndromes (HIES) are a heterogeneous group of inborn errors of immunity sharing manifestations including increased infection susceptibility, eczema, and raised serum IgE. Since the prototypical HIES description 55 years ago, areas of significant progress have included description of key disease-causing genes and differentiation into clinically distinct entities. The first two patients reported had what is now understood to be HIES from dominant-negative mutations in signal transduction and activator of transcription 3 (STAT3-HIES), conferring a broad immune defect across both innate and acquired arms, as well as defects in skeletal, connective tissue, and vascular function, causing a clinical phenotype including eczema, staphylococcal and fungal skin and pulmonary infection, scoliosis and minimal trauma fractures, and vascular tortuosity and aneurysm. Due to the constitutionally expressed nature of STAT3, initial reports at treatment with allogeneic stem cell transplantation were not positive and treatment has hinged on aggressive antimicrobial prophylaxis and treatment to prevent the development of end-organ disease such as pneumatocele. Research into the pathophysiology of STAT3-HIES has driven understanding of the interface of several signaling pathways, including the JAK-STAT pathways, interleukins 6 and 17, and the role of Th17 lymphocytes, and has been expanded by identification of phenocopies such as mutations in IL6ST and ZNF341. In this review we summarize the published literature on STAT3-HIES, present the diverse clinical manifestations of this syndrome with current management strategies, and update on the uncertain role of stem cell transplantation for this disease. We outline key unanswered questions for further study.

Pulmonary Infections and Surgical Complications in a Young Girl with Signal Transducer and Activator of Transcription 3 Loss-of-Function Mutation Hyperimmunoglobulin E Syndrome: A Case Report

Introduction: Hyperimmunoglobulin E syndromes (HIESs) are characterized by a high serum immunoglobulin E (IgE) level, eczematoid rashes, recurrent staphylococcal skin abscesses, and recurrent pneumonia and pneumatocele formation. Autosomal dominant HIES is the most common form of HIES and mainly occurs due to loss-of-function mutations in the Signal Transducer and Activator of Transcription 3 (STAT3) gene (STAT3 LOF). Case Presentation: We report the case of an 11-year-old Peruvian girl diagnosed with STAT3 LOF caused by p.R382W mutation. She presented with recurrent staphylococcal pneumonia and empyema caused by the rarely reported Achromobacter xylosoxidans, which led to severe destruction of the lung parenchyma, multiple lung surgeries, and the development of bronchopleural fistulas. A laparotomy was also performed, which showed evidence of sigmoid colon perforation. The patient received immunoglobulin replacement therapy (IRT) and antibiotic prophylaxis, and the frequency of her infections has decreased over the past 3 years. Conclusion: This is the first case of STAT3 LOF diagnosed by genomic sequencing in Peru. Patients with this mutation have recurrent pulmonary infections, and require multiple surgical procedures with frequent complications. A. xylosoxidans infection could be related to the prolonged stay in intensive care leading to high mortality; therefore, additional care must be taken when treating patients with this infection. In addition, colonic perforation is a rare complication in STAT3 LOF patients. IRT and antibiotic prophylaxis appear to decrease the frequency of infections and hospitalizations.