Journal of Clinical Immunology最新文献

Purpose: This study aimed to investigate the spectrum of bacterial infections in children with inborn error of immunity (IEIs).

Methods: Pediatric patients with IEIs and positive for bacteria considered to be pathogenic were included in this retrospective study.

Results: In this study, 1811 medical records of IEI inpatients were reviewed, and 243 IEI patients with 290 hospitalizations were enrolled. A total of 361 strains were detected, of which, 83 (22.99%) were gram-positive bacteria, and 278 (77.01%) were gram-negative bacteria. The main bacteria isolated from different IEI classifications were different. Patients with combined immunodeficiencies were more likely to have Klebsiella pneumoniae (12.68%) and Pseudomonas aeruginosa (12.68%) isolated. Patients with predominant antibody deficiencies were more prone to the isolation of Haemophilus influenzae (31.82%) and Moraxella catarrhalis (13.64%). Patients with congenital defects of phagocytes were more frequently associated with the isolation of K. pneumoniae (16.84%) and Escherichia coli (11.58%). Patients with different classifications of IEI were susceptible to specific bacteria. Salmonella was often isolated from patients with defects in intrinsic and innate immunity (4.23%), and Staphylococcus aureus was often isolated from patients with combined immunodeficiencies with syndromic features (5.52%). The percentages of methicillin-resistant S. aureus, carbapenem-resistant E. coli, K. pneumoniae, P. aeruginosa, and Acinetobacter baumannii in IEI patients were55.57%, 38.10%, 25.71%, 25.81%, and 70.59%, respectively, and these values were greater than those in non-IEI patients.

Conclusion: Children with IEIs exhibit a unique spectrum of bacterial infections. Bacteria isolated from children with IEIs have high antimicrobial resistance.

Suppressor of cytokine signaling 1 (SOCS1) haploinsufficiency is a recently described inborn error of immunity characterized by autoimmunity, inflammation, lymphoproliferation, and increased infection susceptibility. SOCS1, a negative regulator of cytokine signaling via the JAK/STAT pathway, explains the condition's broad phenotypic variability. Single nucleotide polymorphisms in SOCS1 have been linked to multiple sclerosis (MS), and SOCS1 mimetics have shown efficacy in MS animal models. However, neurological involvement has not been previously reported in patients with SOCS1 insufficiency. We describe a family with a heterozygous SOCS1 variant, highlighting neurological manifestations such as MS, autoimmune encephalitis, and recurrent complex regional pain syndrome as novel features. Next-Generation Sequencing and segregation analysis were performed on PBMCs from patients and healthy donors. Functional studies included luciferase reporter assays in HeLa cells expressing the SOCS1 mutant, flow cytometry for phenotypic analysis, and gene expression profiling of the type-I interferon (IFN) signature. Intraepidermal nerve fiber density was evaluated via immunohistochemistry on skin biopsy. Genetic analysis confirmed the variant's inheritance. Transfected cells carrying the SOCS1 variant showed increased STAT1 transcriptional activity after IFN-γ stimulation. Elevated STAT5 phosphorylation and T-cell proliferation were observed in response to IL-2. Peripheral blood revealed an elevated IFN signature during relapse. Skin biopsy showed reduced intraepidermal nerve fiber density. This report expands the clinical spectrum of SOCS1-related disorders to include neurological symptoms, emphasizing SOCS1's critical role in regulating inflammation in the central and peripheral nervous systems.

Flow cytometric immunophenotyping of lymphocytes and dendritic cells, and functional lymphocyte mitogen response tests are used in the diagnostics of inborn errors of immunity (IEI), especially in pediatrics. These routinely used tests lack sufficient age-matched reference values in children. We established reference values for lymphocyte and dendritic cell subsets for four age groups from 68 healthy children under 12 years of age. These values were then compared to prior publicly available articles and 46 clinical samples from children with confirmed IEI diagnosis. Mitogen response results were also compared between 27 children and 177 adults. In the literature review, we found considerable variability in lymphocyte subset definitions and statistical approaches. Most IEI patients had increased transitional and naïve B, and decreased memory B cells. CHH patients had increased γδ T and DNTs. Lymphocyte stimulation via FASCIA method provides weaker stimulation results in children than in adults, which seems to result from a larger proportional count of naïve lymphocytes in children. The established reference values can be used in diagnostics of pediatric immunological conditions in laboratories that use similar analytic methods. Lower lymphocyte mitogen response results in children need to be taken into consideration when interpreting the results of lymphocyte functional tests.

Background: Treating neutrophilic inflammation in chronic rhinosinusitis with nasal polyps (CRSwNP) remains a challenge. Managing excessive infiltration and activation of neutrophils in tissues is important for improving CRSwNP outcomes. S100A4, a calcium-binding protein, regulates cell migration, chemotaxis and tissue fibrosis. In this study, we sought to examine the role of S100A4 in neutrophilic inflammation in CRSwNP and its involvement in TLR4 signaling.

Methods: Quantitative RT-PCR and immunofluorescence were used to analyze the expression and cellular distribution of S100A4 in sinonasal mucosa. Primary human nasal epithelial cells (hNECs) were cultured and treated with S100A4 to assess cytokine and chemokine production. Additionally, we employed TLR4 inhibitor (TAK-242) to investigate whether S100A4 exert this effect via TLR4 pathway.

Results: We found increased levels of S100A4 mRNA and S100A4⁺ cell number in CRSwNP patients compared with control, with the highest levels in uncontrolled and mixed eosinophilic-neutrophilic CRSwNP. Compared to eosinophils, S100A4 exhibits a stronger correlation with neutrophils. S100A4 was primarily located in inflammatory cells in lamina propria, with neutrophils forming the majority of S100A4⁺ cells. S100A4 treatment led to upregulation of neutrophil chemokines and pro-inflammatory cytokine IL-36γ, in nasal epithelia cells. S100A4 induced effect through TLR4 pathway, and can be inhibited by clarithromycin and dexamethasone.

Conclusion: S100A4 is elevated in neutrophilic CRSwNP and exerts its pro-inflammatory effect on nasal epithelial cells via TLR4 signaling cascade.

X-linked agammaglobulinemia (XLA) is caused by loss-of-function variants in Bruton's tyrosine kinase, leading to absence of circulating B lymphocytes and inability to produce antibodies. Despite the fear that patients with XLA would be at high risk for severe infection when the novel virus SARS-CoV-2 emerged in the society with low pre-existing immunity, most patients with XLA did not suffer from severe disease. However, some patients were critically affected. Factors associated with hospitalization in patients with XLA remain poorly described. Thus, we designed a study to determine risk factors associated with hospitalization due to Covid-19 in patients with XLA. Data was collected from 17 sites in Europe and the US, comprising n = 81 patients, with hospitalization due to SARS-CoV-2 infection in 14 patients. Nearly 17% of patients with XLA required hospitalization due to Covid-19, but only 3 patients had ventilatory support. After correcting for the effect of the date of infection during the early pandemic, univariate and multiple logistic regression analysis showed that preexisting bronchiectasis and lower IgG serum trough levels (< 8 g/L) before infection were associated with an increased risk for hospitalization, with a high rate of superinfection. The lack of vaccination seemed to contribute to this risk, and ambulatory patients had higher amounts of CD4⁺ T cells before infection compared to hospitalized patients. Thus, our data suggests a need for IgG trough levels above 8 g/L, especially in patients with bronchiectasis, to protect patients with XLA during viral infections such as Covid-19 and reduce morbidity due to superinfections.

Haploinsufficiency of cytotoxic T-lymphocyte associated protein 4 (CTLA4), a known cause of inborn errors of immunity, can lead to autoimmunity, inflammation, neoplasia and infections. A previously undescribed CTLA4 variant was identified in a patient who presented with life-threatening cutaneous infection caused by Pseudomonas aeruginosa, severe VZV infection, and Evans syndrome. Our aim was to assess the pathogenicity of the previously undescribed c.379T > G variant in the CTLA4 gene and explore its phenotypic presentation in relatives. We employed genetic and protein-based in silico analyses to evaluate the potential role of the c.379T > G variant in the CTLA4 gene. We subsequently studied CTLA4 expression ex vivo, analyzed the clinical presentation of affected carriers and compared the biological status across affected individuals, healthy carriers and noncarriers. In silico analyses revealed that the c.379T > G mutation, which is located within the ligand binding area of CTLA4, is highly pathogenic. Its clinical manifestations, which are sometimes fatal, include multiple infections, autoimmunity, inflammation of the central nervous system, lymphoproliferation and thymoma with Good's syndrome. Compared with its expression in healthy donors, the expression of CTLA4 following stimulation in memory regulatory T cells was decreased in affected individuals. Immunophenotyping revealed an increased proportion of immature and double-negative B cells in affected patients compared with their nonmutated relatives. Additionally, a reduction in naive T cells and an increase in CD4 + CD25-Foxp3 + cells were observed in carriers compared with controls. The c.379T > G variant of CTLA4, resulting in a p.Tyr127Asp substitution, is pathogenic and contributes to the development of a CTLA4 haploinsufficiency phenotype. This finding highlights the heterogeneous presentations of the disease, including oncological and neurological manifestations.

Intravenous immunoglobulin (IVIG) therapy is a well-documented and effective treatment for primary immunodeficiencies (PI). Subcutaneous immunoglobulins (SCIG) have emerged as an effective alternative for some patients that offers additional flexibility.Currently, caprylate/chromatography purified IGSC (human) 20% is approved to treat PI in North America and many countries worldwide. In this multi-center, open-label study, the pharmacokinetics (PK), efficacy, and safety of IGSC 20% were studied after biweekly (every two weeks) dosing for 16 weeks and compared to weekly IGSC 20% administration for 16 weeks in treatment-experienced PI patients. A loading/weekly maintenance SC regimen was also studied in PI patients naïve to IG treatment.In treatment-experienced patients, the least squares mean ratio of steady-state AUC_0-7 days for biweekly dosing showed non-inferiority to weekly dosing (90% confidence interval 1.0030-1.0685). Other PK parameters (C_max, T_max, steady state trough) were similar between treatments. Efficacy and safety measures were qualitatively similar to previously published results. No serious bacterial infections were reported. Annual rates for any type of infection were similar between the treatment groups. All severe treatment-related adverse events (AEs) were unrelated to treatment. Only mild to moderate suspected adverse drug reactions were observed.PK analyses showed that biweekly dosing of IGSC 20% was non-inferior to weekly dosing in treatment-experienced PI patients. Biweekly dosing had similar patterns to weekly in prevention of serious bacterial infections, rates of all infections and hospitalizations for infections. The IGSC loading/maintenance dosing regimen in naïve patients was safe and effective during the observation period.

Combined immunodeficiency due to CARMIL2 mutations is a rare autosomal recessive primary immunodeficiency characterized by impaired T-cell activation and function, leading to diverse clinical manifestations. Fewer than 50 cases have been reported worldwide. We describe the clinical and genetic features of five patients from Palestine with homozygous CARMIL2 mutations, including the first documented case of recurrent visceral leishmaniasis associated with this gene defect. This retrospective case series was conducted using whole-exome sequencing to confirm the diagnosis. All patients exhibited significant immunologic symptoms, including chronic dermatitis, cutaneous warts, recurrent respiratory infections, and mucocutaneous candidiasis. Two developed cytomegalovirus-related disease. Genetic analysis revealed two novel homozygous variants: NM_001317026.3:c.1865 C > T (p.Ala622Val) in four patients, and c.1973 C > T (p.Ala658Val) in one. Notably, one adult male developed recurrent visceral leishmaniasis, an unusual presentation not previously reported in the context of CARMIL2 deficiency. Consanguinity was identified in two families. All patients required immunomodulatory therapy, and four were evaluated for hematopoietic stem cell transplantation. This case series underscores the clinical heterogeneity of CARMIL2-associated immunodeficiency and highlights the importance of genetic testing in patients with recurrent or atypical infections, particularly in populations with a high prevalence of consanguinity. The novel link to visceral leishmaniasis expands the known phenotypic spectrum of this condition.

Background: IgA vasculitis (IgAV) is an autoimmune disorder characterized by inflammation of the small blood vessels. The pathogenesis of IgAV is believed to involve a complex interplay between immune cells, metabolites, and inflammatory cytokines (ICs).

Methods: We performed two-sample Mendelian randomization (MR) analysis to examine the causal relationship between immune cell traits, metabolites, ICs, and IgAV. Genetic variants associated with exposure, mediators and outcome were extracted from large-scale genome-wide association studies (GWAS). The inverse variance weighted (IVW) method was used as the primary approach, supported by MR Egger, weighted median, simple mode, and weighted mode methods.

Results: In this study, we identified 25 immune cells, 6 metabolites (Threonate, Carnitine C5:1, Chiro-inositol, Carnitine C18:2, 3-formylindole, Cholate to phosphate ratio) and 2 ICs (T - cell surface glycoprotein CD5, Osteoprotegerin) associated with IgAV. Meanwhile, we identified 5 immune cell-metabolites-IgAV pathways (CD28⁺CD45RA^-CD8dim AC-3-formylindole-IgAV; CD28⁺ CD45RA^- CD8dim AC-Cholate to phosphate ratio-IgAV; CD28⁺ CD45RA⁺ CD8br%T cell-3-formylindole-IgAV; CD25 on IgD⁺ CD38^- unswmem-Chiro-inositol- IgAV; HLA DR on CD14⁺ CD16^- monocyte-Chiro-inositol-IgAV; CD39⁺ secreting Treg %secreting Treg-Threonate-IgAV) and 4 immune cells-ICs-IgAV pathways (IgD^- CD38^- AC-Osteoprotegerin-IgAV; CD45 on T-Osteoprotegerin-IgAV; HLA DR on CD14⁺ CD16^- monocyte-CD5-IgAV; HLA DR on CD14⁺CD16^- monocyte-CD5-IgAV).

Conclusions: These results highlight the need for further research to investigate the underlying mechanisms and identify potential therapeutic targets for the treatment of IgAV.