Suppression of Phagocytic Activity Leads to the Efficient Surface Modification of Macrophages with Liposomes for Developing a Biomimetic Drug Delivery System.

Macrophages selectively infiltrate the lesion sites of several diseases, including cancers, and, thus, have attracted attention as a biomimetic drug delivery carrier. To achieve the efficient drug loading of macrophages with minimal cytotoxicity, drugs are preferably encapsulated into nanoparticles, such as liposomes, and modified on the surface of macrophages rather than being incorporated into cells. However, liposomes are rapidly taken up by macrophages after binding to the cell surface because of their strong phagocytic activity. To overcome this, we herein attempted to modify the surface of macrophages with liposomes by suppressing their phagocytic activity using a pretreatment with anionic liposomes. We confirmed that 1,2-distearoyl-sn-glycero-3-phospho-(1'-rac-glycerol) (DSPG)- and cholesterol-rich anionic liposomes were efficiently taken up by RAW264.7 murine macrophage-like cells. Furthermore, the cellular uptake of anionic liposomes by RAW264.7 cells was higher in the absence of fetal bovine serum (FBS) than in its presence. Moreover, the viability of RAW264.7 cells was maintained above 90% when cells were incubated with anionic liposomes for 3 h, whereas viability was markedly decreased after a 24-h incubation. Based on these results, we pretreated RAW264.7 cells by an incubation with DSPG- and cholesterol-rich liposomes for 3 h in the absence of FBS. This pretreatment significantly inhibited the internalization of other liposomes, which subsequently bound to the cell surface. Therefore, we succeeded in modifying the surface of macrophages with liposomes, and liposome-modified macrophages have potential as a biomimetic active drug delivery carrier.

Serum ß2-microglobulin level is a useful indicator of disease activity and hemophagocytic syndrome complication in systemic lupus erythematosus and adult-onset Still's disease.

This study demonstrates whether serum ß2-microglobulin (ß2-MG) level can be an indicator of the status of systemic lupus erythematosus (SLE) and adult-onset Still's disease (AOSD), and development of hemophagocytic syndrome (HPS) complication. Serum ß2-MG level was compared between the active and inactive statuses of SLE and AOSD in hospitalized patients. Active status was defined as a state for which a therapy was introduced. Serum ß2-MG level was also compared between patients with and without HPS complication. HPS was diagnosed on the basis of clinical and pathological findings. Laboratory markers of HPS including peripheral blood cell counts and levels of serum lactate dehydrogenase (LDH), serum ferritin, plasma fibrin/fibrinogen degradation product (FDP), and plasma D-dimer were examined to determine their correlations with serum ß2-MG level. Sixteen SLE and seven AOSD patients (all females, aged 39.0 ± 16.4) were included. The serum ß2-MG level was high in the active status of underlying diseases and decreased significantly after the therapy (3.5 ± 1.4 vs. 2.1 ± 0.8 mg/L, p < 0.001). Among patients with active status, the ß2-MG level was higher in patients with HPS (two with SLE and three with AOSD) than in patients without HPS (4.9 ± 1.8 vs. 3.3 ± 1.4 mg/L, p < 0.05). Serum ß2-MG level significantly correlated with the levels of serum LDH (r(s) = 0.42, p < 0.05), plasma FDP (r(s) = 0.58, p < 0.05), and plasma D-dimer (r(s) = 0.77, p < 0.01). Serum ß2-MG level would be a useful indicator of disease activity and development of HPS complication in patients with SLE and AOSD.