The detected factor, IRF-5, is known for its action in innate immunity cells but is role was totally unknown in CD4 T cells.
The new findings show that IRF-5 leads Th1 cells to self-destruction.
Activation of TLR7 induces expression and activation of IRF-5, which in turn increases expression of DR5 (Death Receptor 5) and caspase 8, two signaling elements leading to cell death.
'We've previously found that a protein called interferon regulatory factor-5 (IRF-5) seems to push macrophages to change from a more 'peaceful', M2-type to the more aggressive M1-type', said Professor Irina Udalova at the Kennedy Institute of Rheumatology at Oxford University, 'so we wondered if 'deleting' IRF-5 might have a beneficial effect'.
To test this idea, the two research teams fed the mice that were lacking the gene coding for IRF-5 with a healthy diet or a high-fat one.
'The mice without IRF-5 still got fat, but what was different was where they deposited this fat.
Apart from IRF1, IRF-3, IRF-7, and IRF-8, some studies have also briefly explored the role of IRF-5 and IRF-9 in malaria infection.
Pitha, "Virus-specific activation of a novel Interferon regulatory factor, IRF-5, results in the induction of distinct interferon alpha genes," The Journal of Biological Chemistry, vol.
Pitha, "Multiple regulatory domains of IRF-5 control activation, cellular localization, and induction of chemokines that mediate recruitment of T lymphocytes," Molecular and Cellular Biology, vol.
In mammals the IRF gene family consists of nine members: IRF-1, IRF2, IRF-3, IRF-4, IRF-5, IRF-6, IRF-7, IRF-8/ICSBP, and IRF-9.
IRF-4 competes with IRF-5 for binding to the adaptor MyD88 that transmits TLR outside-in signaling to NF-[kappa]B and other proinflammatory transcription factors .
IRF-5. IRF-5 is a 504-amino acid-long stress-responsive IRF .