[MicroRNA-155 induces macrophage polarization to M1 in Toxoplasma gon-dii infection]

Area of Science:

• Immunology
• Molecular Biology
• Parasitology

Background:

• Macrophages play a crucial role in the immune response to pathogens like Toxoplasma gondii.
• MicroRNAs (miRNAs) are key regulators of gene expression and cellular processes, including immune cell differentiation.
• Understanding macrophage polarization is vital for controlling parasitic infections.

Purpose of the Study:

• To investigate the differential expression of microRNAs in human macrophages during Toxoplasma gondii infection.
• To determine the role of specific microRNAs in modulating macrophage polarization.
• To elucidate the molecular mechanisms underlying macrophage responses to T. gondii.

Main Methods:

• Microarray analysis and quantitative real-time PCR (qRT-PCR) were used to assess miRNA differential expression.
• THP-1 cells were transfected with pEGFP-miR-155 to study miR-155 function.
• Flow cytometry was employed to detect macrophage surface markers (CD86) and transfection efficiency.
• Enzyme-linked immunosorbent assay (ELISA) and qRT-PCR were used to measure nitric oxide (NO) and interleukin-12 (IL-12) levels.

Main Results:

• miR-155 expression was significantly upregulated (over 4-fold) in T. gondii-infected macrophages, with increased levels correlating with infection duration.
• Transfection of pEGFP-miR-155 into THP-1 cells achieved an 82.6% efficiency.
• T. gondii infection and pEGFP-miR-155 transfection enhanced CD86 expression on macrophages.
• Increased expression of iNOS and IL-12 mRNA was observed, along with elevated NO and IL-12 protein levels.

Conclusions:

• Toxoplasma gondii infection leads to the upregulation of host miR-155 expression.
• miR-155 plays a role in modulating macrophage polarization towards the M1 phenotype.
• These findings contribute to understanding the host-parasite interaction at a molecular level.