Rapid Recruitment and Activation of Macrophages by Anti-Gal/α-Gal Liposome Interaction Accelerates Wound Healing

Abstract

Macrophages are pivotal in promoting wound healing. We hypothesized that topical application of liposomes with glycolipids that carry Gala1-3Galb1-4GlcNAc-R epitopes (α-gal liposomes) on wounds may accelerate the healing process by rapid recruitment and activation of macrophages in wounds. Immune complexes of the natural anti-Gal Ab (constituting ~1% of Ig in humans) bound to its ligand, the α-gal epitope on α-gal liposomes would induce local activation of complement and generation of complement chemotactic factors that rapidly recruit macrophages. Subsequent binding of the Fc portion of anti-Gal coating α-gal liposomes to FcγRs on recruited macrophages may activate macrophage genes encoding cytokines that mediate wound healing. We documented the efficacy of this treatment in α1,3galactosyltrasferase knockout mice. In contrast to wild-type mice, these knockout mice lack α-gal epitopes and can produce the anti-Gal Ab. The healing time of excisional skin wounds treated with α-gal liposomes in these mice is twice as fast as that of control wounds. Moreover, scar formation in α-gal liposome-treated wounds is much lower than in physiologic healing. Additional sonication of α-gal liposomes resulted in their conversion into submicroscopic α-gal nanoparticles. These α-gal nanoparticles diffused more efficiently in wounds and further increased the efficacy of the treatment, resulting in 95–100% regeneration of the epidermis in wounds within 6 d. The study suggests that α-gal liposome and α-gal nanoparticle treatment may enhance wound healing in the clinic because of the presence of high complement activity and high anti-Gal Ab titers in humans.

Exogenous pulmonary surfactant prevents the development of intra‐abdominal adhesions in rats

“…Although no study has evaluated IB4 activity after a gastrointestinal anastomosis, we observed that IB4+ cells, which are consistent with infiltrating macrophages, were frequently present in the region of the gastrointestinal anastomosis in both tested groups. Although some authors claim that alpha‐D‐galactose epitopes on macrophage surfaces accelerate recruitment and promote wound repair 26, we were unable to verify this effect in our model, as there was no significant difference in the number of IB4+ cells in the GE group after treatment with surfactant. Therefore, additional studies are needed to determine the effect of surfactant on the recruitment and activation of macrophages in gastrointestinal anastomotic regions.…”

Macrophages Recruitment and Activation by α-gal Nanoparticles Accelerate Regeneration and Can Improve Biomaterials Efficacy in Tissue Engineering

“…These are submicroscopic !-gal liposomes comprised of glycolipids with multiple !-gal epitopes (!-gal glycolipids), phospholipids and cholesterol [18,19] (Fig. 1).…”

“…1). Since !-gal glycolipids comprise most of the glycolipids in rabbit red blood cell (RBC) membranes and since these cell membranes are the richest source of !-gal glycolipids in mammals [20][21][22][23], rabbit RBC are a convenient natural source for preparation of !-gal liposomes and !-gal nanoparticles [18,19,24]. For this purpose, glycolipids, phospholipids and cholesterol are extracted from rabbit RBC membranes in a solution of chloroform and methanol [25].…”

“…The number of !-gal epitopes on !-gal nanoparticles is very high, corresponding to ~10 15 !-gal epitopes per mg !-gal nanoparticles [18]. From 1 liter of rabbit RBC it is possible to prepare 3-4 grams of !-gal nanoparticles.…”

“…These include C5a and C3a complement cleavage peptides which induce rapid migration of macrophages into the site of !-gal nanoparticles application (Fig. 1A) [18]. In studies with !-gal nanoparticles injected intradermal in anti-Gal producing GT-KO mice, macrophages were found to be recruited by this chemotactic mechanism.…”