Transcription factor ELF4 promotes development and function of memory CD8+T cells inListeria monocytogenesinfection

A Novel Frameshift Variant of the ELF4 Gene in a Patient with Autoinflammatory Disease: Clinical Features, Transcriptomic Profiling and Functional Studies

We described the diagnosis and treatment of a patient with autoinflammatory disease, named "Deficiency in ELF4, X-linked (DEX)". A novel ELF4 variant was discovered and its pathogenic mechanism was elucidated. The data about clinical, laboratory and endoscopic features, treatment, and follow-up of a patient with DEX were analyzed. Whole exome sequencing and Sanger sequencing were performed to identify potential pathogenic variants. The mRNA and protein levels of ELF4 were analyzed by qPCR and Western blotting, respectively. The association of ELF4 frameshift variant with nonsense-mediated mRNA decay (NMD) in the pathogenesis DEX was examined. Moreover, RNA-seq was performed to identify the key molecular events triggered by ELF4 variant. The relationship between ELF4 and IFN-β activity was validated using a dual-luciferase reporter assay and a ChIP-qPCR assay. An 11-year-old boy presented with a Behçet's-like phenotype. The laboratory abnormality was the most obvious in elevated inflammatory indicators. Endoscopy revealed multiple ileocecal ulcers. Intestinal histopathology showed inflammatory cell infiltrations. The patient was treated with long-term immunosuppressant and TNF-α blocker (adalimumab), which reaped an excellent response over 16 months of follow-up. Genetic analysis identified a maternal hemizygote frameshift variant (c.1022del, p.Q341Rfs*30) in ELF4 gene in the proband. The novel variant decreased the mRNA level of ELF4 via the NMD pathway. Mechanistically, insufficient expression of ELF4 disturbed the immune system, leading to immunological disorders and pathogen susceptibility, and disrupted ELF4-activating IFN-β responses. This analysis detailed the clinical characteristics of a Chinese patient with DEX who harbored a novel ELF4 frameshift variant. For the first time, we used patient-derived cells and carried out transcriptomic analysis to delve into the mechanism of ELF4 variant in DEX.

[Two Cases of Behcet's Disease-Like Syndrome with Gene Deficiency in ELF4]

The patient 1, a 13-year-old boy, was admitted due to "recurrent oral ulcers for 3 years, abdominal pain for 8 months, and perianal ulcers for 10 days"; The patient 2, a 3-year-old boy, was admitted due to "recurrent abdominal pain, diarrhea, and fever for over 3 months". Genetic testing of both patients revealed "deficiency in ELF4, X-linked" (DEX), and the patients were diagnosed with Behcet's disease-like syndrome due to deficiency in ELF4, accordingly. The patient 1 was successively given intravenous methylprednisolone pulses and oral prednisone and mesalazine for symptomatic treatment. The patient 2 was successively treated with corticosteroids combined with enteral nutrition, as well as oral mercaptopurine. Subsequently, both patients showed improvements in symptoms and were discharged.

Current understanding of ELF4 deficiency: a novel inborn error of immunity

BACKGROUND

ELF4 deficiency has been recently recognized as a novel disorder within the spectrum of inborn errors of immunity (IEIs), specifically categorized as a "disease of immune dysregulation." Cases of this condition, reported by our team and others, are very limited worldwide. As such, our current knowledge of this new disease remains preliminary. This review aims to provide a brief overview of the clinical manifestations, pathogenesis, and treatment strategies for this novel IEI.

DATA SOURCES

A comprehensive review was conducted after an extensive literature search in the PubMed/Medline database and websites concerning transcriptional factor ELF4 and reports concerning patients with ELF4 deficiency. Our search strategy was "ELF4 OR ETS-related transcription factor Elf-4 OR EL4-like factor 4 OR myeloid Elf-1-like factor" as of the time of manuscript submission.

RESULTS

The current signature manifestations of ELF4 deficiency disorder are recurrent and prolonged oral ulcer, abdominal pain, and diarrhea in pediatric males. In some cases, immunodeficiency and autoimmunity can also be prominent. Targeted Sanger sequencing or whole exome sequencing can be used to detect variation in ELF4 gene. Western blotting for ELF4 expression of the patient's cells can confirm the pathogenic effect of the variant. To fully confirm the pathogenicity of the variant, further functional test is strongly advised. Glucocorticoid and biologics are the mainstream management of ELF4 deficiency disorder.

CONCLUSIONS

Pediatric males presenting with recurring ulcerations in digestive tract epithelium with or without recurrent fever should be suspected of DEX. When atypical presentations are prominent, variations in ELF4 gene should be carefully evaluated functionally due to the complex nature of ELF4 function. Experience of treating DEX includes use of glucocorticoid and biologics and more precise treatment needs more patients to identify and further mechanistic study.

A Multicenter Cohort Study of Immune Dysregulation Disorders Caused by ELF4 Variants in China

Patients with DEX (deficiency in ELF4, X-linked) were recently reported by our team and others, and cases are very limited worldwide. Our knowledge of this new disease is currently preliminary. In this study, we described 5 more cases presenting mainly with oral ulcer, inflammatory bowel disease-like symptoms, fever of unknown origin, anemia, or systemic lupus erythematosus. Whole exome sequencing identified potential pathogenic ELF4 variants in all cases. The pathogenicity of these variants was confirmed by the detection of ELF4 expression in peripheral blood mononuclear cells from patients and utilizing a simple IFN-b luciferase reporter assay, as previously reported. Our findings significantly contribute to the current understanding of DEX.

Cerebrospinal fluid proteomics indicates immune dysregulation and neuronal dysfunction in antibody associated autoimmune encephalitis

Autoimmune Encephalitis (AE) spans a group of non-infectious inflammatory conditions of the central nervous system due to an imbalanced immune response. Aiming to elucidate the pathophysiological mechanisms of AE, we applied an unsupervised proteomic approach to analyze the cerebrospinal fluid (CSF) protein profile of AE patients with autoantibodies against N-methyl-d-aspartate receptor (NMDAR) (n = 9), leucine-rich glioma-inactivated protein 1 (LGI1) (n = 9), or glutamate decarboxylase 65 (GAD65) (n = 8) compared to 9 patients with relapsing-remitting multiple sclerosis as inflammatory controls, and 10 patients with somatic symptom disorder as non-inflammatory controls. We found a dysregulation of the complement system, a disbalance between pro-inflammatory and anti-inflammatory proteins on the one hand, and dysregulation of proteins involved in synaptic transmission, synaptogenesis, brain connectivity, and neurodegeneration on the other hand to a different extent in all AE subtypes compared to non-inflammatory controls. Furthermore, elevated levels of several proteases and reduction in protease inhibitors could be detected in all AE subtypes compared to non-inflammatory controls. Moreover, the different AE subtypes showed distinct protein profiles compared to each other and inflammatory controls which may facilitate future identification of disease-specific biomarkers. Overall, CSF proteomics provides insights into the complex pathophysiological mechanisms of AE, including immune dysregulation, neuronal dysfunction, neurodegeneration, and altered protease function.

Loss of Function Mutation in ELF4 Causes Autoinflammatory and Immunodeficiency Disease in Human

Monogenic autoinflammatory diseases (mAIDs) are a heterogeneous group of diseases affecting primarily innate immunity, with various genetic causes. Genetic diagnosis of mAIDs can assist in the patient's management and therapy. However, a large number of sporadic and familial cases remain genetically uncharacterized. Deficiency in ELF4, X-linked (DEX) is recently identified as a novel mAID. Here, we described a pediatric patient suffering from recurrent viral and bacterial respiratory infection, refractory oral ulcer, constipation, and arthritis. Whole-exome sequencing found a hemizygous variant in ELF4 (chrX:129205133 A > G, c.691 T > C, p.W231R). Using cells from patient and point mutation mice, we showed mutant cells failed to restrict viral replication effectively and produced more pro-inflammatory cytokines. RNA-seq identified several potential critical antiviral and anti-inflammation genes with decreased expression, and ChIP-qPCR assay suggested mutant ELF4 failed to bind to the promoters of these genes. Thus, we presented the second report of DEX.

Elf4 regulates lysosomal biogenesis and the mTOR pathway to promote clearance of Staphylococcus aureus in macrophages

Staphylococcus aureus is a major cause of infectious disease. Macrophages can directly destroy most of the invading bacteria through the phagolysosomal pathway. E74-like factor 4 (Elf4) is one of the important transcription factors that controls diverse pathogens, but the role of Elf4 in macrophage-mediated S. aureus eradication is unknown. Our data show that Elf4 is induced by S. aureus in macrophages. Elevated expression of Elf4 results in decreased bacterial load and inflammatory responses during S. aureus infection in vivo and in vitro. Elf4-overexpressed macrophages have decreased mTOR activity and increased lysosomal mass. Collectively, these results suggest that S. aureus induces Elf4 expression, which enhances lysosomal function and increases the capacity of macrophages to eliminate intracellular pathogens.

Roles and regulations of the ETS transcription factor ELF4/MEF

Most E26 transformation-specific (ETS) transcription factors are involved in the pathogenesis and progression of cancer. This is in part due to the roles of ETS transcription factors in basic biological processes such as growth, proliferation, and differentiation, and also because of their regulatory functions that have physiological relevance in tumorigenesis, immunity, and basal cellular homoeostasis. A member of the E74-like factor (ELF) subfamily of the ETS transcription factor family—myeloid elf-1-like factor (MEF), designated as ELF4—has been shown to be critically involved in immune response and signalling, osteogenesis, adipogenesis, cancer, and stem cell quiescence. ELF4 carries out these functions as a transcriptional activator or through interactions with its partner proteins. Mutations in ELF4 cause aberrant interactions and induce downstream processes that may lead to diseased cells. Knowing how ELF4 impinges on certain cellular processes and how it is regulated in the cells can lead to a better understanding of the physiological and pathological consequences of modulated ELF4 activity.

Novel tumor-suppressor function of KLF4 in pediatric T-cell acute lymphoblastic leukemia

Acute lymphoblastic leukemia (ALL) is the most common hematological malignancy in pediatric patients. Despite advances in the treatment of this disease, many children with T-cell ALL (T-ALL) die from disease relapse due to low responses to standard chemotherapy and the lack of a targeted therapy that selectively eradicates the chemoresistant leukemia-initiating cells (LICs) responsible for disease recurrence. We reported recently that the reprogramming factor Krüppel-like factor 4 (KLF4) has a tumor-suppressive function in children with T-ALL. KLF4 silencing by promoter deoxyribonucleic acid (DNA) methylation in patients with T-ALL leads to aberrant activation of the mitogen-activated protein kinase kinase MAP2K7 and the downstream c-Jun NH₂-terminal kinase (JNK) pathway that controls the expansion of leukemia cells via c-Jun and activating transcription factor 2. This pathway can be inhibited with small molecules and therefore has the potential to eliminate LICs and eradicate disease in combination with standard therapy for patients with refractory and relapsed disease. The present review summarizes the role of the KLF4-MAP2K7 pathway in T-ALL pathogenesis and the function of JNK and MAP2K7 in carcinogenesis and therapy.

Role of Ets Proteins in Development, Differentiation, and Function of T-Cell Subsets

Through positive selection, double-positive cells in the thymus differentiate into CD4(+) or CD8(+) T single-positive cells that subsequently develop into different types of effective T cells, such as T-helper and cytotoxic T lymphocyte cells, that play distinctive roles in the immune system. Development, differentiation, and function of thymocytes and CD4(+) and CD8(+) T cells are controlled by a multitude of secreted and intracellular factors, ranging from cytokine signaling modules to transcription factors and epigenetic modifiers. Members of the E26 transformation specific (Ets) family of transcription factors, in particular, are potent regulators of these CD4(+) or CD8(+) T-cell processes. In this review, we summarize and discuss the functions and underlying mechanisms of the Ets family members that have been characterized as involved in these processes. Ongoing research of these factors is expected to identify practical applications for the Ets family members as novel therapeutic targets for inflammation-related diseases.