HIV-1 does not alter in vitro and in vivo IL-10 production by human monocytes and macrophages

Abstract

The present study analyses the ability of HIV-1 to modulate IL-10 production in cells of monocyte-macrophage lineage cultured in the presence of macrophage colony-stimulating factor (M-CSF). Both monocytes and macrophages spontaneously produced low amount of IL-10. Lipopolysaccharide (LPS) induced a strong IL-10 response in fresh monocytes and in M-CSF-treated macrophages. In contrast, macrophages cultured in the absence of M-CSF exhibited a marked decrease in their susceptibility to LPS stimulation. M-CSF increased the IL-10 response of macrophages to LPS by enhancing both the expression of membrane-bound CD14, the protein that serves as LPS receptor, and the sensibility of CD14-expressing cells to LPS stimulation. Neither spontaneous nor LPS-induced expression of IL-10 was modulated in monocytes and macrophages by infection with eight monocytotropic strains, as demonstrated by ELISA and cytofluorimetric analysis. In contrast, all the HIV-1 strains primed macrophages for an increased IL-6 response to LPS stimulation. To determine whether IL-10 production was associated with in vivo infection, monocytes from AIDS individuals were analysed for IL-10 production. We found that neither spontaneous nor LPS-induced IL-10 production were different between healthy controls and HIV-infected patients. Taken together, these data strongly suggest that HIV-1 infection of monocytes-macrophages does not play a significant role in the regulation of IL-10 in infected patients. This study also emphasizes the role of M-CSF activation in the regulation of the cytokine response in macrophages.

Fig. 1

IL-10 production by monocytes and macrophages stimulated or not with lipopolysaccharide (LPS) and macrophage colony-stimulating factor (M-CSF). At given time points, macrophage cultures were washed, refed with fresh medium with or without LPS and M-CSF. After 48 h of incubation, the supernatants were obtained for IL-10 determination. The data represent the mean of three experiments each carried out in duplicate. Each experiment was performed with cells from a single donor. The error bars represent s.e.m.

Fig. 2

IL-10 production by monocytes and macrophages infected with different HIV-1 isolates. (a) Monocytes. (b) Macrophages. The levels of IL-10 in uninfected controls were the same as in Fig. 1a,b. Cell cultures were considered infected if the levels of HIV-p24 antigen in the supernatants were equal to or more than those presented in Table 2. The data represent the mean of three experiments each carried out in duplicate. The error bars represent s.e.m.

Fig. 3

IL-6 production by HIV-infected macrophages. The cells were cultured in the presence of macrophage colony-stimulating factor (M-CSF) and stimulated by lipopolysaccharide (LPS) when HIV-p24 antigen in the supernatants was equal to or more than that presented in Table 2. The supernatants were harvested after 24 h of incubation. The data represent the mean of three experiments each carried out in duplicate. The error bars represent s.e.m.

Fig. 4

Cytofluorimetric assessment of individual IL-10- and HIV-p24 antigen-producing cells in lipopolysaccharide (LPS)-stimulated macrophages by specific two-colour, intracellular staining. (a,b) Uninfected and HIV-Ba-L-infected macrophages cultured in the absence of macrophage colony-stimulating factor (M-CSF). (c,d) Uninfected and HIV-Bal-infected macrophages cultured in the presence of M-CSF. The data are displayed as bivariate dot plots. The quadrants were set according to the negative controls (< 1% of the isotype control cells appeared positive). Low left quadrants, unstained cells; upper left quadrants, HIV-p24-stained cells; low right quadrants, IL-10-stained cells; upper right quadrants, cells stained for both IL-10 and HIV-p24. Five thousand to 10 000 cells were analysed for each sample. The data refer to a typical experiment of three performed with similar results.