An early-onset SLE patient with a novel paternal inherited BACH2 mutation.

BACH2-related immunodeficiency and autoimmunity (BRIDA) is an inborn error of immunity, newly reported in 2017, presenting with symptoms of immunoglobulin deficiency and ongoing colitis. Studies using a mouse model have demonstrated that BACH2 deficiency predisposes individuals to systemic lupus erythematosus (SLE); however, no BACH2 deficiency has been reported in SLE patients. Here we describe a patient with BRIDA presenting with early-onset SLE, juvenile dermatomyositis, and IgA deficiency. Whole exome sequencing analysis of the patient and her parents revealed a novel heterozygous point mutation in BACH2, c.G1727T, resulting in substitution of a highly conserved arginine with leucine (R576L), which is predicted to be deleterious, in the patient and her father. Reduced BACH2 expression and deficient transcriptional repression of the BACH2 target, BLIMP1, were detected in PBMCs or lymphoblastoid cell lines of our patient. Notably, extreme reduction of memory B cells was detected in the patient's father, although he had no obvious symptoms. SLE symptoms and recurrent fever were relieved by treatment with prednisone combined with tofacitinib. Thus, we present the second report of BRIDA and demonstrate that BACH2 may be a monogenic cause of SLE.

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.

Clinical characteristics of early-onset paediatric systemic lupus erythematosus in a single centre in China.

OBJECTIVES: We sought to investigate the sex distribution, clinical presentations, disease outcomes and genetic background of early-onset paediatric SLE (eo-pSLE) in a single centre in China to help enable early diagnosis and timely treatment. METHODS: The clinical data of children aged less than 5 years old with SLE (n = 19) from January 2012 to December 2021 were reviewed and analysed. We performed DNA sequencing in 11 out of 19 patients to survey the genetic aetiologies. RESULTS: Our study included 6 males and 13 females. The mean age at onset was 3.73 years. The median diagnostic delay was 9 months and was longer in male patients (P = 0.02). Four patients had an SLE-relevant family history. The most common clinical manifestations at diagnosis were fever, rash and hepatosplenomegaly. ANA positivity and low C3 were identified in all children. The renal (94.74%), mucocutaneous (94.74%), haematological (89.47%), respiratory (89.47%), digestive (84.21%), cardiovascular (57.89%) and neuropsychiatric (52.63%) systems were involved to varying degrees. We identified 13 SLE-associated gene mutations in 9 out of 11 patients: TREX1, PIK3CD, LRBA, KRAS, STAT4, C3, ITGAM, CYBB, TLR5, RIPK1, BACH2, CFHR5 and SYK. One male patient showed a 47, XXY chromosomal abnormality. CONCLUSION: Early-onset (<5 years) pSLE is characterized by an insidious onset, typical immunological patterns, and the involvement of multiple organs. Immunological screening and genetic testing should be performed as soon as feasible in patients with an early onset of multisystemic autoimmune diseases to confirm the diagnosis.

Trends in TREC values according to age and gender in Chinese children and their clinical applications.

T cell receptor excision circles (TRECs) are small circularized DNA elements produced during rearrangement of T cell receptor (TCR) genes. Because TRECs are fairly stable, do not replicate during mitosis, and are not diluted during division of naïve T cells (Dion et al. [1]), they are suitable for assessing the number of newly formed T cells (Ping and Denise [2]). In this study, we detected TRECs in 521 healthy Chinese children aged 0-18 years in different clinical settings. The TRECs decrease with aging and show lower levels in preterm and low birth weight (BW) babies compared to those in full-term infants, while the preterm babies can also show comparable levels of TRECs when they have a gestation age (GA)-matched BW. We found a strong correlation between TRECs and peripheral CD4 naïve T cell numbers, which was age-related. We also analyzed the TRECs in different PIDs. Since T cell defects vary in PIDs, TREC levels change inconsistently. For example, in Wiskott-Aldrich syndrome (WAS), combining the level of TREC with lymphocyte subsets can help to distinguish subtypes of disease.Conclusion: We established the reference value range for TRECs by evaluating children below 18 years old in China, which could be used to screen for PIDs during early life. What is Known: • The TREC levels are decreased with age, and there is a positive correlation between TRECs and the numbers of naïve T cells. What is New: • This is the largest study to determine TREC reference levels in healthy Chinese pediatric, we provide solid data showing a correlation between CD4 naïve T cell counts and TREC levels according to age. We point out the GA matched BW is need to be considered during the SCID newborn screening. We are the first group showed that TREC levels can help clinician distinguish different WAS phenotype.

The early activation of memory B cells from Wiskott-Aldrich syndrome patients is suppressed by CD19 downregulation.

Wiskott-Aldrich syndrome (WAS) pediatric patients exhibit a deficiency in humoral immune memory. However, the mechanism by which Wiskott-Aldrich syndrome protein (WASP) regulates the differentiation and activation of memory B cells remains elusive. Here we examine the early activation events of memory B cells from the peripheral blood mononuclear cells of WAS patients and age-matched healthy controls (HCs) using total internal reflection fluorescence microscopy. In response to stimulation through the B-cell receptor (BCR), memory B cells from HCs showed significantly higher magnitudes of BCR clustering and cell spreading than naive B cells from the same individuals. This was associated with increases in CD19 recruitment to the BCR and the activation of its downstream signaling molecule Btk and decreases in FcγRIIB recruitment and the activation of its downstream molecule Src homology 2-containing inositol 5' phosphatase (SHIP). However, these enhanced signaling activities mediated by CD19 and Btk are blocked in memory B cells from WAS patients, whereas the activation of FcγRIIB and SHIP was increased. Although the expression levels of CD19, Btk, and FcγRIIB did not change between CD27(-) and CD27(+) B cells of HCs, the protein and mRNA levels of CD19 but not Btk and FcγRIIB were significantly reduced in both CD27(-) and CD27(+) B cells of WAS patients, compared with those of HCs. Overall, our study suggests that WASP is required for memory B-cell activation, promoting the activation by positive regulating CD19 transcription and CD19 recruitment to the BCR.

Abnormalities of follicular helper T-cell number and function in Wiskott-Aldrich syndrome.

Wiskott-Aldrich syndrome protein (WASp) is a hematopoietic-specific regulator of actin nucleation. Wiskott-Aldrich syndrome (WAS) patients show immunodeficiencies, most of which have been attributed to defective T-cell functions. T follicular helper (Tfh) cells are the major CD4(+) T-cell subset with specialized B-cell helper capabilities. Aberrant Tfh cells activities are involved in immunopathologies such as autoimmunity, immunodeficiencies, and lymphomas. We found that in WAS patients, the number of circulating Tfh cells was significantly reduced due to reduced proliferation and increased apoptosis, and Tfh cells were Th2 and Th17 polarized. The expression of inducible costimulator (ICOS) in circulating Tfh cells was higher in WAS patients than in controls. BCL6 expression was decreased in total CD4(+) T and Tfh cells of WAS patients. Mirroring the results in patients, the frequency of Tfh cells in WAS knockout (KO) mice was decreased, as was the frequency of BCL6(+) Tfh cells, but the frequency of ICOS(+) Tfh cells was increased. Using WAS chimera mice, we found that the number of ICOS(+) Tfh cells was decreased in WAS chimera mice, indicating that the increase in ICOS(+) Tfh cells in WAS KO mice was cell extrinsic. The data from in vivo CD4(+) naive T-cell adoptive transfer mice as well as in vitro coculture of naive B and Tfh cells showed that the defective function of WASp-deficient Tfh cells was T-cell intrinsic. Consistent findings in both WAS patients and WAS KO mice suggested an essential role for WASp in the development and memory response of Tfh cells and that WASp deficiency causes a deficient differentiation defect in Tfh cells by downregulating the transcription level of BCL6.

Clinical and immunological characteristics of five patients with immune dysregulation, polyendocrinopathy, enteropathy, X-linked syndrome in China-expanding the atypical phenotypes.

Background: Immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome is a rare disorder of the immune regulatory system caused by forkhead box P3 (FOXP3) mutations. Abnormal numbers or functions of regulatory T (Treg) cells account for the various autoimmune symptoms. We aimed to explore the molecular genetics and phenotypic spectra of patients with atypical IPEX syndrome in China. Methods: We analyzed the molecular, clinical and immune phenotype characteristics of five Chinese patients with FOXP3 mutations. Results: We summarized the molecular and phenotypic features of five patients with FOXP3 mutations, including two novel mutations. Four of the five patients displayed atypical phenotypes, and one developed immune-related peripheral neuropathy. Three of the five patients showed normal frequencies of Treg cells, but the proportions of subsets of Treg cells, CD4+ T cells and B cells were out of balance. Conclusions: Our report broadens the understanding of the clinical features of atypical IPEX syndrome. Our detailed analyses of the immunological characteristics of these patients enhance the understanding of the possible mechanisms underlying the clinical manifestations.

Identification of Key Biomarkers and Immune Infiltration in Systemic Juvenile Idiopathic Arthritis by Integrated Bioinformatic Analysis.

Systemic juvenile idiopathic arthritis (sJIA) is a rare and serious type of JIA characterized by an unknown etiology and atypical manifestations in the early stage, and early diagnosis and effective treatment are needed. We aimed to identify diagnostic biomarkers, immune cells and pathways involved in sJIA pathogenesis as well as potential treatment targets. The GSE17590, GSE80060, and GSE112057 gene expression profiles from the Gene Expression Omnibus (GEO) database were screened to obtain differentially expressed genes (DEGs) between sJIA and healthy controls. Common DEGs were subjected to pathway enrichment analysis; a protein-protein interaction network was constructed, and hub genes were identified. In addition, functional annotation of hub genes was performed with GenCLiP2. Immune infiltration analysis was then conducted with xCell, and correlation analysis between immune cells and the enriched pathways identified from gene set variation analysis was performed. The Connectivity Map database was used to identify candidate molecules for treating sJIA patients. Finally, quantitative reverse transcription-polymerase chain reaction (qRT-PCR) was carried out, and the GEO dataset GSE8361 was applied for validation of hub gene expression levels in blood samples from healthy individuals with sJIA. A total of 73 common DEGs were identified, and analysis indicated enrichment of neutrophil and platelet functions and the MAPK pathway in sJIA. Six hub genes were identified, of which three had high diagnostic sensitivity and specificity; ARG1 and PGLYRP1 were validated by qRT-PCR and microarray data of the GSE8361 dataset. We found that increased megakaryocytes and decreased Th1 cells correlated positively and negatively with the MAPK pathway, respectively. Furthermore, MEK inhibitors and some kinase inhibitors of the MAPK family were identified as candidate agents for sJIA treatment. Our results indicate two candidate markers for sJIA diagnosis and reveal the important roles of platelets and the MAPK pathway in the pathogenesis of sJIA, providing a new perspective for exploring potential molecular targets for sJIA treatment.

WASp Deficiency Selectively Affects the TCR Diversity of Different Memory T Cell Subsets in WAS Chimeric Mice.

Background: The T cell receptor (TCR) diversity is essential for effective T cell immunity. Previous studies showed that TCR diversity in Wiskott-Aldrich Syndrome (WAS) patients was severely impaired, especially in the memory T cell populations. Whether this defect was caused by intrinsic WASp deficiency or extrinsic reasons is still unclear. Methods: We sorted different T cell subsets from the bone marrow chimeric mice model using both magnetic beads and flow cytometry. TCR repertoires of memory T cells, especially CD4+ effector memory T (TEM) cells and CD8+ central memory T (TCM) cells, were analyzed using the UMI quantitative high-throughput sequencing (HTS). Results: An average of 5.51 million sequencing reads of 32 samples was obtained from the Illumina sequencing platform. Bioinformatic analyses showed that compared with wild type (WT), WAS knock out (KO)-CD4+ TEM cells exhibited increased Simpson index and decreased D50 index (P <0.05); The rank abundance curve of KO-CD4+ TEM cells was shorter and steeper than that of WT, and the angle of qD and q in KO-CD4+ TEM cells was lower than that of WT, while these indexes showed few changes between WT and KO chimeric mice in the CD8+TCM population. Therefore, it indicated that the restriction on the TCRVß repertoires is majorly in KO-CD4+ TEM cells but not KO- CD8+ TCM cells. Principal Component Analysis (PCA), a comprehensive parameter for TCRVß diversity, successfully segregated CD4+ TEM cells from WT and KO, but failed in CD8+ TCM cells. Among the total sequences of TRB, the usage of TRBV12.2, TRBV30, TRBV31, TRBV4, TRBD1, TRBD2, TRBJ1.1, and TRBJ1.4 showed a significant difference between WT-CD4+ TEM cells and KO-CD4+ TEM cells (P <0.05), while in CD8+ TCM cells, only the usage of TRBV12.2 and TRBV20 showed a substantial difference between WT and KO (P <0.05). No significant differences in the hydrophobicity and sequence length of TCRVß were found between the WT and KO groups. Conclusion: WASp deficiency selectively affected the TCR diversity of different memory T cell subsets, and it had more impact on the TCRVß diversity of CD4+ TEM cells than CD8+ TCM cells. Moreover, the limitation of TCRVß diversity of CD4+ TEM cells and CD8+ TCM cells in WAS was not severe but intrinsic.

IL-21 Rescues the Defect of IL-10-Producing Regulatory B Cells and Improves Allergic Asthma in DOCK8 Deficient Mice.

Mutations in human DOCK8 cause a combined immunodeficiency syndrome characterized by allergic diseases such as asthma and food allergy. However, the underlying mechanism is unclear. Regulatory B (Breg) cells that produce IL-10 exert potent immunosuppressive functions in patients with allergic and autoimmune disorders. DOCK8-deficient B cells show diminished responses to TLR9 signaling, suggesting a possible defect in IL-10-producing Breg cells in those with DOCK8 deficiency, which may contribute to allergies. Here, we isolated peripheral blood mononuclear cells from DOCK8-deficient patients and generated a Dock8 KO mouse model to study the effect of DOCK8 deficiency on Breg cells. DOCK8-deficient patients and Dock8 KO mice harbored quantitative and qualitative defects in IL-10-producing Breg cells; these defects were caused by abnormal Dock8-/- CD4+ T cells. We found that recombinant murine (rm)IL-21 restored the function of Bregs both in vitro and in Dock8 KO mice, leading to reduced inflammatory cell infiltration of the lungs in a murine asthma model. Overall, the results provide new insight into the potential design of Breg-based or IL-21-based therapeutic strategies for allergic diseases, including asthma associated with DOCK8 deficiency.

Altered Functions of Neutrophils in Two Chinese Patients With Severe Congenital Neutropenia Type 4 Caused by G6PC3 Mutations.

Background: SCN4 is an autosomal recessive disease caused by mutations in the G6PC3 gene. The clinical, molecular, and immunological features; function of neutrophils; and prognosis of patients with SCN4 have not been fully elucidated. Methods: Two Chinese pediatric patients with G6PC3 mutations were enrolled in this study. Clinical data, genetic and immunologic characteristics, and neutrophil function were evaluated in patients and controls before and after granulocyte colony-stimulating factor (G-CSF) treatment. Results: Both patients had histories of pneumonia, inguinal hernia, cryptorchidism, and recurrent oral ulcers. Patient 1 also had asthma and otitis media, and patient 2 presented with prominent ectatic superficial veins and inflammatory bowel disease. DNA sequencing demonstrated that both patients harbored heterozygous G6PC3 gene mutations. Spontaneous and FAS-induced neutrophil apoptosis were significantly increased in patients, and improved only slightly after G-CSF treatment, while neutrophil respiratory burst and neutrophil extracellular traps production remained impaired in patients after G-CSF treatment. Conclusion: G-CSF treatment is insufficient for patients with SCN4 patients, who remain at risk of infection. Where possible, regular G-CSF treatment, long-term prevention of infection, are the optimal methods for cure of SCN4 patients. It is important to monitor closely for signs of leukemia in SCN4 patients. Once leukemia occurs in SCN4 patients, hematopoietic stem cell transplantation is the most important choice of treatment.

A Novel Homozygous Mutation Destabilizes IKKß and Leads to Human Combined Immunodeficiency.

Mutations in the IKBKB gene cause severe immunodeficiency, characterized clinically by persistent respiratory or gastrointestinal infections. Targeted gene panel sequencing revealed a novel homozygous missense mutation in the IKBKB gene of a patient with immune dysregulation and combined T and B cell functional defects. PBMCs from the patient, Ikbkb Y397H mice, and transfected cells were used to elucidate how the Y395H mutation triggers IKKß deficiency and impairs immune function. Here, we found that cells from both the patient and Ikbkb Y397H mice lacked or showed decreased levels of IKKß protein, along with impaired lymphocyte function. IKKα and IKKγ protein expression by human PBMCs harboring the Y395H mutation was normal, but degradation of IKKß protein was accelerated. Binding of human NF-κB to DNA in patient PBMCs fell upon stimulation with TNF-α or LPS. Additionally, a structural model of Y395H revealed loss of the hydrogen bond with D389. These data suggest that IKBKB deficiency induces abnormal IKKß protein degradation, leading to impaired NF-κB signaling and immune function. We postulate that the Y395H variant in the IKKß protein lost the hydrogen bond with D389, thereby affecting interaction between Y395 and D389 and increasing protein instability.

Abnormal distribution of distinct lymphocyte subsets in children with Wiskott-Aldrich syndrome.

Wiskott-Aldrich syndrome (WAS) is a severe and rare primary immunodeficiency. Several studies show that WAS protein (WASp) plays a key role in the function of certain lymphocyte subsets. So far, no study has described distinct immunophenotypic abnormalities associated with WAS; thus the prognostic significance of any such abnormalities is unclear. This study examined many differences in the percentage/absolute numbers of distinct lymphocyte subsets in 20 WAS patients and 20 age/sex-matched healthy controls, and analyzed the association between these abnormalities and clinical disease scores. The results showed that the numbers of CD4+ T cells, B cells, and CD8+ naïve T cells were significantly lower in WAS patients; furthermore, the numbers in WASp-negative patients were lower than those in WASp-positive patients. WAS patients showed a selective reduction in expression of CD19 by naïve and transitional B cells. There was a negative association between the number of B cells and the WAS clinical scores. Also, CD8+ naïve T cell numbers in patients with a score of 3-5A were lower than those in patients with a score of 2. The absence of WASp leads to a reduction in the population of specific lymphocyte subsets; therefore, these findings may help future management of patients with WAS.

Defective thymic output in WAS patients is associated with abnormal actin organization.

Wiskott-Aldrich syndrome protein (WASp) is a key regulator of the actin cytoskeleton. Defective T - cell function is a major cause for immune deficiency in Wiskott-Aldrich syndrome (WAS) patients. T cells originate in the bone marrow and develop in the thymus, and then migrate to peripheral tissues. TCR excision circles (TRECs) present in thymic output cells stably, which is used as a molecular marker for thymic output. We found that CD8+ T naïve cells of classic WAS patients were significantly reduced, and TRECs in patients with classic WAS and X-linked thrombocytopenia (XLT) dramatically decreased compared with that of HCs. TRECs were also reduced in WAS (KO) mice. These suggest that defective thymic output partially accounts for T cell lymphopenia in WAS patients. However, the correlation between the defect of thymic output and actin organization still remains elusive. We found that the subcellular location and the levels of of F-actin were altered in T cells from both WAS and XLT patients compared to that of HCs with or without stimulation. Our study shows that WASp plays a critical role in thymic output, which highly correlates with the subcellular location and level of F-actin in T cells.

Novel DOCK8 gene mutations lead to absence of protein expression in patients with hyper-IgE syndrome.

Autosomal recessive hyper-immunoglobulin E syndrome (AR-HIES) caused by DOCK8 defects is characterized by recurrent elevated serum IgE level, elevated peripheral eosinophil count, severe atopy, recurrent viral and bacterial infections, and early-onset malignancy. The clinical, genetic, and immunologic characteristics of DOCK8 mutations in Chinese patients have not been characterized in detail. In this research, we screened seven Chinese candidate patients for mutations within the DOCK8 gene and identified three large novel homozygous deletions and four novel point mutations by targeted deep sequencing. The homozygous deletions displayed autosomal recessive inheritance, and the point mutations were sporadic. Absence of DOCK8 protein was confirmed using flow cytometry and western blotting. Besides the typical clinical features and immunologic impairments of DIDS, proliferation of lymphocytes, cytotoxic function of NK cells, and expression of IL-10 in regulatory B cells were severely impaired in DOCK8 mutant patients which may be associated with abnormal immune responses in DIDS. These findings will contribute to the early diagnosis and treatment of DOCK8 patients.

Clinical, immunologic, and genetic characteristics of RAG mutations in 15 Chinese patients with SCID and Omenn syndrome.

Mutations in Recombination Activating Genes (RAG1 and RAG2) are common genetic causes of severe combined immunodeficiency (SCID) and Omenn syndrome (OS). The clinical, immunologic, and genetic characteristics of RAG mutations in Chinese patients with SCID or OS have not been studied in detail. In this research, 22 RAG mutations were identified in 15 Chinese patients, including 10 novel mutations in RAG1 (R108X, M630T, E510X, S666P, E669K, C730Y, A857V, K847E, L922PfsX7, and L1025FfsX39) and 4 in RAG2 (R73C, I427GfsX12, P432L, and 311insL). L1025FfsX39 is a potential RAG1 hot-spot mutation in the Chinese population. The distribution of RAG1 mutations rather than mutation type seemed to differ between SCID and OS patients. The thymic output of T lymphocytes, TCR rearrangement, and T cell proliferation were severely impaired in RAG mutant patients. These findings will contribute to the early diagnosis and treatment of SCID and OS to a certain extent.

Clinical, molecular, and T cell subset analyses in a small cohort of Chinese patients with hyper-IgM syndrome type 1.

Type 1 hyper-IgM syndrome (HIGM1) is a rare primary immunodeficiency disease caused by mutations in the CD40L gene. Patients often present with recurrent infections and autoimmune manifestations. We investigated the clinical and molecular characteristics of HIGM1 in thirteen patients from the Chinese mainland and examined the proportion of CD4(+)CD25(+)FoxP3(+)Treg, Th17, and Th1 cells in the peripheral blood. We identified ten distinct CD40L mutations in eleven patients: one missense mutation, one nonsense mutation, one insertion mutation (in frame), and seven deletions. Six of these mutations were novel. We observed the percentage of Tregs in the peripheral blood of HIGM1 patients decreased markedly compared with that in healthy controls, but no statistically significant differences was found in the percentages of Th17 and Th1. The identified mutations reflect the heterogeneity of the CD40L gene in HIGM1. Precise genetic diagnosis of HIGM1 will enable appropriate therapeutic interventions, reliable detection of carriers, and genetic counseling. Skewed Treg, Th17/Treg, and Th1/Treg profiles may be associated with immune responses to autoimmunity or infection, which requires replication in larger studies.