No abstract

SummaryOur purpose was to determine whether numbers of CD4 + CD25 + T [T regulatory (Treg)] cells and mRNA expression of functional molecules of Treg are related to airway allergy and disease severity in 51 paediatric patients with allergic rhinitis or bronchial asthma and 47 healthy controls. Surface markers were evaluated with flow cytometry, and mRNA was determined with realtime polymerase chain reaction. Children with allergic disease had fewer CD4 + CD25 + T cells (8·49% Ϯ 2·41% versus 9·58% Ϯ 2·43%, P < 0·05) and CD4 + CD25 hi T cells (1·32% Ϯ 0·68% versus 1·70% Ϯ 0·68%, P < 0·01) than control subjects. Numbers of CD4 + CD25 + and CD4 + CD25 hi T lymphocytes were higher in children with persistent allergic rhinitis and/or moderatesevere bronchial asthma than in those with respective milder disease. The number of Treg cells was correlated positively with total immunoglobulin E level. The mRNA expression of forkhead box P3 (FoxP3) was increased in moderate-severe versus mild asthma (2·93 Ϯ 0·38 versus 1·60 Ϯ 0·31, P < 0·01). Patients with moderate-severe bronchial asthma also had increased mRNA expression of interleukin (IL)-10 compared with patients with mild asthma (15·24 Ϯ 4·07 versus 3·77 Ϯ 2·18, P < 0·01). The suppressive function of Treg cells from patients with more severe asthma was competent in vitro. On average, decreased numbers of Treg cells in children with allergic airway disease might represent a defect of the Treg population. With increased expression of FoxP3 and IL-10 in Treg from patients with relatively severe allergic disease, adaptive and functional Treg might be generated in response to aggravated atopy and disease severity.

As a prototype of genomics-guided precision medicine, individualized thiopurine dosing based on pharmacogenetics is a highly effective way to mitigate hematopoietic toxicity of this class of drugs. Recently, NUDT15 deficiency was identified as a genetic cause of thiopurine toxicity, and NUDT15-informed preemptive dose reduction was quickly adopted in clinical settings. To exhaustively identify pharmacogenetic variants in this gene, we developed massively parallel NUDT15 function assays to determine the variants’ effect on protein abundance and thiopurine cytotoxicity. Of the 3,097 possible missense variants, we characterized the abundance of 2,922 variants and found 54 hotspot residues at which variants resulted in complete loss of protein stability. Analyzing 2,935 variants in the thiopurine cytotoxicity-based assay, we identified 17 additional residues where variants altered NUDT15 activity without affecting protein stability. We identified structural elements key to NUDT15 stability and/or catalytical activity with single amino acid resolution. Functional effects for NUDT15 variants accurately predicted toxicity risk alleles in patients treated with thiopurines with far superior sensitivity and specificity compared to bioinformatic prediction algorithms. In conclusion, our massively parallel variant function assays identified 1,152 deleterious NUDT15 variants, providing a comprehensive reference of variant function and vastly improving the ability to implement pharmacogenetics-guided thiopurine treatment individualization.

Summary CD4+ CD25+ regulatory T cells (Tregs) are critical in maintaining self‐tolerance and preventing organ‐specific autoimmunity. Their role in paediatric systemic lupus erythematosus (SLE), an autoimmune disease characterized by inappropriate regulation of hyperactivated B and T cells, has not been clearly defined. Using flow cytometry to determine cell populations and real‐time polymerase chain reaction to assay mRNA expression for FOXP3, CTLA‐4, and GITR, we characterized CD4+ CD25+ T cells in paediatric SLE patients and healthy subjects. The frequency of CD4+ CD25+ Tregs was significantly decreased in patients with active SLE compared with patients with inactive SLE and with controls (7·27% ± 2·50%, 9·59% ± 2·80% and 9·78% ± 2·11%, respectively; P = 0·027 and P < 0·001, respectively), and was inversely correlated with disease activity, as assessed with the Systemic Lupus Erythematosus Disease Activity Index 2000 scores (r = −0·59, P = 0·001) and serum anti‐double‐stranded DNA levels (r = −0·65, P < 0·001). Our preliminary investigations found elevated surface expression of GITR in CD4+ CD25+ T cells, elevated mRNA expression of CTLA‐4 in CD4+ T cells and higher amounts of mRNA expression for FOXP3 in CD4+ cells in patients with active SLE compared with patients with inactive disease and controls. We demonstrated reduced CD4+ CD25+ Treg levels were inversely correlated with disease activity, indicating a defective Treg population in paediatric SLE patients. The differences in the expression of FOXP3, CTLA‐4 and GITR imply the possible role of CD4+ Tregs in the pathogenesis of SLE.

Insurance claim data provide useful information on the epidemiology of HSP in Taiwan. Childhood HSP in Taiwan, with an incidence of 12.9 per 100 000 children, occurs commonly in autumn and winter; and at the age of 5 to 6 yr. The characteristics presented in this study may provide valuable data for understanding and further studies of HSP.