Expression Of Factor Forkhead Box P3 Research Articles

Forkhead Box P3 Regulates TLR10 Expression in Human T Regulatory Cells

Although functionally relevant TLRs can be expressed on human T regulatory (Treg) cells, little is known about the transcriptional control of their expression. We hypothesized that the transcription factor forkhead box P3 (FOXP3) regulates the expression of TLR family members in human Treg cells. Using primary human T cells and a reporter assay in Jurkat T cell lines, we dissected the regulation of TLR10, a TLR highly expressed in human Treg cells. We determined that TLR10 was expressed in human Treg cells through quantitative PCR, Western blotting, and flow cytometry. DNA binding of FOXP3 to a suspected cis-regulatory region in proximity to the transcription start site of TLR10 was established through EMSA and chromatin immunoprecipitation. Transcriptional control of TLR10 by FOXP3 was determined through luciferase reporter assays in Jurkat T cell lines. Relevance of FOXP3 to TLR10 gene transcription in primary T cells was established through the transfection of primary CD4(+)CD25(-)FOXP3(-) T cells with a FOXP3 expression vector, which resulted in prompt production of TLR10 mRNA. Enhanced expression of TLR10 protein in primary Treg cells was induced in a calcium-dependent fashion through TCR activation. The suspected promotional cooperation between FOXP3 and NF-AT was established in the abolition of the luciferase signal upon transfection of a mutant FOXP3 devoid of NF-AT-binding activity. These results suggest that human Treg cells express TLR10, and this expression is regulated through a cooperative complex of FOXP3 and NF-AT.

No Alterations in the Frequency of FOXP3+ Regulatory T-Cells in Type 1 Diabetes

Regulatory T-cells (Tregs) play a critical role in maintaining dominant peripheral tolerance. Previous characterizations of Tregs in type 1 diabetes have used antibodies against CD4 and alpha-chain of the interleukin-2 receptor complex (CD25). This report extends those investigations by the addition of a more lineage-specific marker for Tregs, transcription factor forkhead box P3 (FOXP3), in subjects with type 1 diabetes, their first-degree relatives, and healthy control subjects. With inclusion of this marker, two predominant populations of CD4(+)CD25(+) T-cells were identified: CD4(+)CD25(+)FOXP3(+) as well as CD4(+)FOXP3(-) T-cells expressing low levels of CD25 (CD4(+)CD25(LOW)FOXP3(-)). In all study groups, the frequency of CD4(+)CD25(+)FOXP3(+) cells was age independent, whereas CD4(+)CD25(LOW)FOXP3(-) cell frequencies strongly associated with age. In terms of additional markers for delineating cells of Treg lineage, FOXP3(+) cells were CD127(-) to CD127(LOW) whereas CD25(+) cells were less restricted in their expression of this marker, with CD127 expressed across a continuum of levels. Importantly, no differences were observed in the frequency of CD4(+)CD25(+)FOXP3(+) T-cells in individuals with or at varying degrees of risk for type 1 diabetes. These investigations suggest that altered peripheral blood frequencies of Tregs, as defined by the expression of FOXP3, are not specifically associated with type 1 diabetes and continue to highlight age as an important variable in analysis of immune regulation.