ALS iPSC-Derived M2 Macrophages Induce Functional Tregs from ALS Teffs
M2, M0, or M1 cells derived from iPSCs were co-cultured with ALS Teffs at a ratio of 1:1/4 (Teffs:M2) for 2 days. Cells were then subjected for flow cytometric analyses.
(A) Representative plots showed CD25 and Foxp3 expression of CD4+ T-cells in ALS Teffs either cultured alone or co-cultured with M2 cells derived from one CTR25 iPSC, one ALS29 C9 iPSC.
(B) The percentages of CD4+CD25+Foxp3+ Tregs in ALS M2+ALS Teffs (n = 3) and ALS M0+ALS Teffs (n = 3) were higher than ALS M1+ALS Teffs (n = 3) or ALS Teffs alone (n = 3). No differences were observed between ALS M1+ALS Teffs and ALS Teffs alone. ∗∗∗p<0.001 vs. ALS Teffs alone; ##p<0.01, #p<0.05 vs. ALS M1+ALS Teffs.
(C) M2 cells from ALS C9 iPSCs (n = 3) and sporadic ALS iPSCs (n = 4) increased the percentage of CD4+CD25+Foxp3+ Tregs from ALS Teffs compared with ALS Teffs alone cultures; Treg induction capacity of M2 cells from both ALS C9 and sporadic iPSCs were not different from CTR M2 cells (n = 3). ∗∗∗p<0.001 vs. ALS Teffs alone.
(D) M2-induced CD4+CD25+ Tregs were isolated from M2+ALS Teffs co-cultures. These M2-induced Tregs (iTregs(M2)) were then co-cultured with CFSE-stained responder Teffs from ALS patients for 5 days at different Teffs:Tregs(M2) ratio (1:1/8, 1:1/4, 1:1/2, 1:1). Tregs induced by CTR M2 (n = 3) and ALS iPSC M2 (n = 5) suppressed proliferation of ALS Teffs similarly in a dose-dependent manner.