Research Assistant I Beth Israel Deaconess Med. Ctr., Harvard Med. Sch., United States
Disclosure(s):
William Li, BA: No financial relationships to disclose
Introduction/Rationale: In autoimmune hepatitis (AIH), regulatory T cell (Treg) impairment contributes to T effector-mediated liver damage and is linked to altered response to aryl hydrocarbon receptor (AhR), a transcription factor that modulates Treg immune responses upon binding its canonical partner, aryl hydrocarbon receptor nuclear translocator (ARNT). AhR also binds to Krüppel-like-factor-6 (KLF6) that modulates the expression of genes involved in lipid metabolism, on which Tregs rely for function. We investigated if KLF6 alterations contribute to Treg dysfunction in AIH.
Methods: Tregs were isolated from the peripheral blood of AIH patients and healthy subjects (HS). Treg KLF6 levels were measured by qPCR and flow cytometry. Intrahepatic KLF6+ Tregs were identified by immunofluorescence. Lipid peroxidation was measured by flow cytometry using BODIPY 581/591 C11 in KLF6 siRNA-treated Tregs. Treg suppressive function was tested in co-culture experiments, measured as inhibition of CD4+CD25- responder cell proliferation.
Results: KLF6 is upregulated in AIH Tregs at mRNA and protein levels. KLF6+ Tregs are more frequent in liver biopsies of AIH compared to control patients. Compared to HS, AIH Tregs display heightened intracellular lipid peroxidation and higher oxidized-to-non-oxidized lipid ratio, which is directly correlated with ALT levels. Silencing KLF6 downregulates lipid peroxidation and ameliorates suppressive function in AIH but not HS Tregs. Analysis of publicly available datasets derived from RNAseq studies conducted on Tregs from healthy subjects showed that high KLF6 levels are associated with gene sets linked to T cell activation and inflammation, including PI3K, ERK and Notch signaling pathways.
Conclusion: AIH Tregs show upregulated KLF6 and increased lipid peroxidation. Blocking KLF6 limits lipid peroxidation and enhances Treg suppression, suggesting that aberrant KLF6 impacts Treg function by altering lipid peroxidation. Blocking KLF6 shows therapeutic potential by rebalancing Treg lipid metabolism.
