Figure 8: iNOS deficiency promotes the M1 macrophage differentiation in vivo.

WT or iNOS^−/− mice were injected (i.v) with 2 × 10⁴ CFU of viable L. monocytogenes for 2 days. (a) Mice were killed and spleens and livers were removed. Spleens and livers were homogenized and viable bacteria were numerated by the pour plate method after serial dilution. Data represent mean±s.d. (n=5), unpaired Student’s t-test, *P<0.05. (b) The sera level of IL-6 and IL-12p40 was determined by ELISA. Data represent mean±s.d. (n=5), unpaired Student’s t-test, *P<0.05. (c) Total cellular RNA was extracted from spleens, and qPCR was performed for the analysis of mRNA expression of indicated genes. The data are representative of two similar experiments, unpaired Student’s t-test, *P<0.05, **P<0.01. (d) C57Bl/6 mice were transferred with 2 × 10⁶ WT macrophages or iNOS^−/− macrophages for 24 h, and the recipient mice were then challenged with LPS (800 μg mouse⁻¹). The survival of mice was observed (n=8 in each group). Kaplan–Meier method was used to estimate overall survival and the Log-rank test was applied to determine the difference of survival rate; *P<0.05. (e) The recipient mice were challenged with LPS (800 μg mouse⁻¹) for 6 h, and sera level of cytokines was determined by ELISA, unpaired Student’s t-test, *P<0.05. (f) The recipient mice were challenged with LPS (800 μg mouse⁻¹) for 6 h and spleens were removed. Total cellular RNA was extracted, and qPCR was performed for the analysis of mRNA expression of indicated genes. The data are representative of two similar experiments, unpaired Student’s t-test, *P<0.05, **P<0.01.