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. 2007 Sep 28;3(9):e134. doi: 10.1371/journal.ppat.0030134

Figure 5. Imatinib Blocks M-CSF Signaling and Restores TRAIL Sensitivity of Infected Macrophages.

Figure 5

(A) Imatinib inhibits M-CSF–dependent autophosphorylation of the M-CSF receptor. Macrophages were incubated for 16 h with 2 μM Imatinib mesylate before stimulation with recombinant M-CSF for 5 min. The M-CSF receptor was immunoprecipitated from cell lysates, and M-CSF–dependent tyrosine autophosphorylation was determined by Western blotting and densitometry.

(B) Imatinib upregulates TRAIL-R1 expression on wild-type–infected macrophages. HIV-1 wild-type– and Δenv-infected macrophages were incubated with Imatinib for 16 h and TRAIL-R1 levels were determined by flow cytometry.

(C) Macrophages from three donors were treated as in (B), and statistical analysis was performed on the mean expression of TRAIL-R1 in response to Imatinib (ANOVA; error bars, SEM).

(D) Imatinib restores sensitivity to TRAIL. Macrophages were incubated with Imatinib for 16 h, challenged with soluble TRAIL, or both. Apoptotic HIV-1–infected and uninfected cells in the same cultures were determined 6 h later by Annexin V and propidium iodide staining and flow cytometry. Apoptotic cells were Annexin V+, propidium iodide− (lower right quadrant). Imatinib renders HIV-1 wild-type–infected macrophages susceptible to TRAIL-mediated apoptosis.

(E) Macrophages were treated as in (D), except apoptosis was determined 16 h after TRAIL exposure by ELISA for apoptotic histone-associated cellular DNA fragmentation in macrophage lysates (cell death ELISA; error bar, SD).