TNF activates a NF-kappaB-regulated cellular program in human CD45RA- regulatory T cells that modulates their...

Area of Science:

• Immunology
• Molecular Biology
• Autoimmunity

Background:

• Regulatory T cells (Tregs) are crucial for maintaining self-tolerance.
• Treg dysfunction contributes to autoimmunity, as seen in rheumatoid arthritis where TNF impairs Treg function.
• A clear mechanism for TNF's regulation of Tregs was previously lacking.

Purpose of the Study:

• To elucidate the molecular mechanism by which TNF regulates human Tregs.
• To investigate the role of the NF-kappaB pathway in TNF-mediated Treg modulation.
• To identify specific molecular targets of TNF signaling in Tregs.

Main Methods:

• Comparative analysis of NF-kappaB pathway activation in human Tregs versus conventional T cells upon TNF stimulation.
• Transcriptional profiling of TNF-treated Tregs (CD45RA(-)FOXP3(+)) to identify affected gene programs.
• Flow cytometry (FACS) to assess cell surface expression of TNFR superfamily members.
• Functional assays to evaluate Treg suppressive capacity before and after TNF treatment and TNFR2 blockade.

Main Results:

• TNF preferentially activates the canonical NF-kappaB pathway in human Tregs compared to conventional T cells.
• TNF induces a distinct transcriptional program in CD45RA(-) Tregs, including genes like lymphotoxin-alpha, TNF, FAS, 4-1BB, and OX-40.
• TNF upregulates cell surface expression of 4-1BB and OX40 specifically on CD45RA(-)FOXP3(+) Tregs.
• TNF treatment impairs Treg suppressive function, which is reversed by anti-TNFR2 antibody treatment.

Conclusions:

• TNF regulates Tregs primarily through NF-kappaB activation and induction of specific gene programs, not by altering core Treg signature or FOXP3 levels.
• TNFR2 signaling is critical for TNF's modulation of Treg function.
• These findings provide mechanistic insight into TNF and TNFR2's role in autoimmune pathogenesis.