Figure 4. IGFBPL1 is required for sustaining microglial homeostasis in healthy and glaucomatous retinas.

(A) Quantifications of microglial cell body area and process length and percentages of CD68⁺ microglia in retinal flat mounts of WT and KO mice. *p < 0.05, **p < 0.01, ***p < 0.001; Student’s t test. n = 4 mice/group.

(B and C) Relative mRNA levels of activated microglia markers (B) and pro-inflammatory cytokines (C) 7-month-old KO retinas normalized to those of WT mice. *p < 0.05, ***p < 0.001; Student’s t test. n = 4 mice/group.

(D) tSNE map of microglial pools of 7-month-old mouse retinas. A total of 4 clusters of microglia were identified. n = 10 mice.

(E) tSNE plots showing distributions of pan-microglial (Cx3cr1, Tmem119), C1 (Apoe, Igf1), C2 (Cxcl10), and C3 (Ki67) markers.

(F) Dot plot of microglial signature genes identified in C0–C3.

(G) Bar plot representing the relative distribution of C0–C3 microglial subsets in WT, KO, and MB-induced glaucomatous WT mice that received PBS or IGFBPL1 treatment. The abundance was normalized to that of the naive WT mice.

(H) RNA velocity ForceAtlas2-based embeddings showing microglial cell-fate directions in all clusters (top panel) or in inflammatory C1 subset (bottom panel) in WT, KO, MB+PBS, and MB+IGFBPL1 retinas. Black arrows indicate the local differentiation direction from individual progenitor to progeny cell. The large red and green arrowheads indicate summed directions of cell-fate transition in C1 subset. Colors of subclusters are in correspondence to those in (D).

Data are mean ± SEM.

See also Figure S3.