Polarized innate immunity: conservation of macrophage polarization in carp

Summary:

When pathogens such as parasites, bacteria or viruses enter the body they almost immediately encounter the innate immune system. The innate immune system is rapidly activated to control and destroy the pathogens but is also essential to repair the damage after having resolved the infection. Mammalian macrophages are important ‘orchestrators’ of these innate immune responses and play important roles in situations from inflammation to healing. Pathogen control, inflammation and clearance require entirely different immune responses than tissue repair and healing. This requires macrophages to become ‘polarized’ and perform very different and sometimes even opposite functions. Based on indications that such polarized macrophages could also exist in fish, we studied the conservation of polarized macrophages in carp. We characterized polarized carp macrophages as inflammatory and anti-inflammatory (or healing) on a functional, transcriptional and metabolic level.