Phagocytosis of Astaxanthin-Loaded Microparticles Modulates TGFβ Production and Intracellular ROS Levels in J774A.1 Macrophages

Abstract

Radiation-induced fibrosis is a serious long-lasting side effect of radiation therapy. Central to this condition is the role of macrophages that, activated by radiation-induced reactive oxygen species and tissue cell damage, produce pro-inflammatory cytokines, such as transforming growth factor beta (TGFβ). This, in turn, recruits fibroblasts at the site of the lesion that initiates fibrosis. We investigated whether astaxanthin, an antioxidant molecule extracted from marine and freshwater organisms, could help control macrophage activation. To this purpose, we encapsulated food-grade astaxanthin from Haematococcus pluvialis into micrometer-sized whey protein particles to specifically target macrophages that can uptake material within this size range by phagocytosis. The data show that astaxanthin-loaded microparticles are resistant to radiation, are well-tolerated by J774A.1 macrophages, induce in these cells a significant reduction of intracellular reactive oxygen species and inhibit the release of active TGFβ as evaluated in a bioassay with transformed MFB-F11 fibroblasts. Micro-encapsulation of bioactive molecules is a promising strategy to specifically target phagocytic cells and modulate their own functions.

Effects of Combination Treatments with Astaxanthin-Loaded Microparticles and Pentoxifylline on Intracellular ROS and Radiosensitivity of J774A.1 Macrophages

“…Full details concerning the synthesis of ASX-loaded microparticles along with their complete biochemical and biological characterization have been given in reference [ 11 ]. In this work we used the same preparations and in this section we describe new data concerning PTX and its interactions with ASX microparticles.…”

“…In our previous work, we showed that ASX microparticles were not cytotoxic for J774A.1 macrophage cells [ 11 ]. To the best of our knowledge no information is available on the safety of PTX in this cell system.…”

“…Astaxanthin (ASX) is a xanthophyll ketocarotenoid with an antioxidant potential 100 times higher than vitamin E [ 10 ]. We previously explored in vitro whether ASX could be effective against RIF [ 11 ]. ASX was encapsulated into µm-sized protein particles that can only be taken up by cells through phagocytosis, and in this way, we could target them specifically to macrophages [ 11 ].…”

“…We previously explored in vitro whether ASX could be effective against RIF [ 11 ]. ASX was encapsulated into µm-sized protein particles that can only be taken up by cells through phagocytosis, and in this way, we could target them specifically to macrophages [ 11 ]. In these cells, ASX microparticles significantly reduced intracellular ROS levels and, importantly, the secretion of bioactive transforming growth factor β (TGFβ) [ 11 ].…”

“…ASX was encapsulated into µm-sized protein particles that can only be taken up by cells through phagocytosis, and in this way, we could target them specifically to macrophages [ 11 ]. In these cells, ASX microparticles significantly reduced intracellular ROS levels and, importantly, the secretion of bioactive transforming growth factor β (TGFβ) [ 11 ]. The role of this pro-inflammatory cytokine is central to fibrosis because it promotes fibroblasts recruitment, and local deposition of extracellular matrix components [ 12 ].…”