A 7-Amino Acid Peptide Mimic from Hepatitis C Virus Hypervariable Region 1 Inhibits Mouse Lung Th9 Cell Differentiation by Blocking CD81 Signaling during Allergic Lung Inflammation

Figure 5

Inhibition of CD81 by siRNAs or 7P significantly reduces Th9 cell differentiation from naïve CD4⁺ T cells. (a–c) Three CD81 siRNAs were transfected into naïve CD4⁺ T cells. Mouse naïve CD4⁺ T cells transfected with CD81 siRNAs were differentiated into Th9 cells with anti-CD3 (3 μg/mL), anti-CD28 (3 μg/mL), anti-INF-γ (3 μg/mL), TGF-β (10 ng/mL), and IL-4 (10 ng/mL) for 4–5 days. Cd81, Il9, and Irf4 mRNA were then examined in three CD81 siRNA-transfected cells and sham siRNA-transfected cells. Data are expressed as ( independent experiments). compared with sham siRNA cells. The human cDNA-CD81 plasmid was successfully transfected into primary human peripheral blood naïve CD4⁺ T cells and the Jurkat cell line. Human CD81 overexpression dramatically promotes Th9 cell differentiation in vitro in human primary naïve CD4⁺ T cells and the Jurkat cell line, as revealed by (d, f) qPCR and (e, g) FACS. (e, g) CD81 signaling was activated with an anti-CD81 antibody, and Th9 cell differentiation was promoted in CD81-overexpressed human primary naïve CD4⁺ T and Jurkat cells. Anti-CD81 antibody during Th9 cell differentiation is significantly inhibited by 7P in both overexpressed CD81 in human primary naïve CD4⁺ T and Jurkat cells (, ).

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