Fig. 2. SP-A and C1q act through Myo18A to enhance IL-4-induced proliferation and activation of alveolar and peritoneal macrophages, respectively.
(A) Murine macrophages were treated with IL-4 in the presence or absence of SP-A or C1q. BrdU incorporation and secretion of Ym1 are shown. (B) For aMϕs, 5 μg IL-4c was delivered ip at d0 and d2, and BAL cells analyzed at d4. For pMϕs, 1 μg IL-4c was delivered ip at d0, and peritoneal cells analyzed at d1: BrdU incorporation and RELMα expression are shown. (C) Murine macrophages were treated with anti-Myo18A or rabbit IgG plus either IL-4+SP-A (aMϕ) or IL-4+C1q (pMϕ). BrdU incorporation and secretion of Ym1 are shown. (D) Myo18A expression on the surface of macrophages from WT, SP-A-/-, and C1qa-/- mice treated with or without IL-4c as described in (B). Concurrently with IL-4c delivery, some WT mice were intra-nasally treated with either anti-Myo18A or rabbit IgG antibody at d2 and d3, and samples analyzed at d4. BrdU incorporation is shown. All statistical analysis was performed by ANOVA followed by the Bonferroni multiple-comparison test. (A+C) Results are presented as means (± SEM) from three different cell cultures with at least three biological replicates. *p < 0.05, **p < 0.01, and ***p < 0.001, when compared with untreated cells; °p < 0.05, °°p < 0.01, and °°°p < 0.001, when SP-A+IL-4- or C1q+IL4-treated are compared with IL-4-treated; ##p < 0.01, and ###p < 0.001, the effect of anti-Myo18A antibody on cells treated with SP-A+IL-4 or C1q+IL4. (B+D) Data were pooled from three independent experiments (means ± SEM) (PBS: 6 mice, other groups: 9 mice). *p < 0.05, **p < 0.01, and ***p < 0.001, when compared with PBS treated mice; °p < 0.05, when WT vs. C1qa-/- mice treated with IL-4c are compared (B) °p < 0.05, °°p < 0.01, and °°°p < 0.001 when anti-Myo18A vs rabbit IgG treatment is compared in IL-4c-treated mice (D).