Flow cytometric identification and cell-line establishment of macrophages in naked mole-rats.

Naked mole rats (NMRs) have extraordinarily long lifespans and anti-tumorigenic capability. Recent studies of humans and mice have shown that many age-related diseases, including cancer, are strongly correlated with immunity, and macrophages play particularly important roles in immune regulation. Therefore, NMR macrophages may contribute to their unique phenotypes. However, studies of the roles of macrophages are limited by material restrictions and the lack of an established experimental strategy. In this study, we developed a flow cytometric strategy to identify NMR macrophages. The NMR macrophages were extractable using an off-the-shelf anti-CD11b antibody, M1/70, and forward/side scatter data obtained by flow cytometry. NMR macrophages proliferated in response to human/mouse recombinant M-CSF and engulfed Escherichia coli particles. Interestingly, the majority of NMR macrophages exhibited co-staining with an anti-NK1.1 antibody, PK136. NK1.1 antigen crosslinking with PK136 results in mouse NK cell stimulation; similarly, NMR macrophages proliferated in response to NK1.1 antibody treatment. Furthermore, we successfully established an NMR macrophage cell line, NPM1, by transduction of Simian virus 40 early region that proliferated indefinitely without cytokines and retained its phagocytotic capacity. The NPM1 would contribute to further studies on the immunity of NMRs.

Protective efficacy of a sulfated sialyl lipid (NMSO3) against human rotavirus-induced diarrhea in a mouse model.

Antiviral activity of sulfated sialyl lipid (NMSO3) against human rotavirus (RV) was examined in vitro and in vivo. NMSO3 inhibited the replication of four major serotypes (G1 to G4) of human rotavirus with a low 50% effective concentration of 1 to 5 microg/ml and 50% cytotoxic concentration of 153 microg/ml when determined by plaque assays with MA104 cells. Exposure of NMSO3 to HCl (pH 2.0) for 30 min exhibited no loss of anti-RV activity. Time-of-addition experiments revealed that NMSO3 inhibited the adsorption of four serotypes of RV to MA104 cells. Furthermore, an assay of virus binding with radiolabeled RVs revealed that NMSO3 inhibited the binding of virus to MA104 cells, suggesting that NMSO3 may bind to VP4 and/or VP7. Prophylactic oral administration of NMSO3 (10 microg three times per day, 4 days) to five suckling mice starting 30 min before inoculation of MO strain (3 x 10(6) PFU/mouse) prevented the development of diarrhea. Four of five mice showed no stool or brown formed stool, and only one mouse showed brown soft stool, while water treatment caused watery diarrhea in all five mice. The mean titer of antibody to RV in mice which received NMSO3 at 10 microg three times per day for 4 days was significantly lower than that of untreated, infected mice. NMSO3 is a promising candidate for the prophylactic treatment of human RVs.