Human herpesvirus-6 dysregulates monocyte-mediated anticryptococcal defences

Area of Science:

• Immunology
• Infectious Diseases
• Mycology

Background:

• Monocytes are key immune cells targeted by neurotropic pathogens like Cryptococcus neoformans (Cn) and human herpesvirus 6 (HHV-6).
• Coinfections involving these pathogens can alter immune cell function and disease outcomes, particularly in the central nervous system.

Purpose of the Study:

• To investigate the in vitro interaction between Cryptococcus neoformans and human herpesvirus 6 in the monocytic cell line THP-1.
• To determine how HHV-6 influences monocyte-mediated defense against fungal pathogens.

Main Methods:

• An in vitro model using the THP-1 monocytic cell line was established.
• THP-1 cells were co-cultured with HHV-6-producing lymphocytes and exposed to Cryptococcus neoformans.

Main Results:

• THP-1 cells exposed to HHV-6-producing lymphocytes showed increased phagocytosis of Cn compared to cells exposed to cell-free virus.
• This enhanced phagocytosis occurred after 24 hours of co-culture and was independent of direct cell-to-cell contact.
• While monocytes exhibited enhanced secretory responses in the presence of HHV-6, their ability to control fungal infection was reduced, facilitating Cn survival and replication.

Conclusions:

• Human herpesvirus 6 may dysregulate monocyte-mediated anti-cryptococcal defenses.
• The interaction results in an overall pro-fungal outcome, suggesting HHV-6 can compromise the host's ability to combat Cryptococcus neoformans infections.