Figure 1.
Lactosylceramide (LacCer) is the key branching point of sphingolipid biosynthesis.
In the synthetic pathway of sphingolipids, four alternate pathways (lacto-series, neolacto-series, globo-series, and isoglobo-series) branch-off from LacCer. GM3S−/− mice, in which the GM3 synthase gene is disrupted, produced only o-series gangliosides, including GA2 and GA1, and not a-series or b-series gangliosides.
Figure 2.
Clinical features related to GM3 in patients with RA or OA. A.
Histology of RA and OA patients. Hematoxylin and eosin (HE) staining. Scale bars = 200 µm. B. Quantification of total GSL glycans in human synovium (n = 5 per group). C. Absolute and relative amounts of GM3 glycans in human synovium (n = 5 per group). D. Quantification of GM3S mRNA in synovium and PBMCs in RA and OA patients (n = 5 per group). Data shown are mean ± SEM. *P<0.05, compared to OA patients.
Figure 3.
Quantification of GM3S mRNA in synovial tissues and spleens from C57BL/6 naïve and CIA mice.
Mice were anesthetized and killed on day 35 after CII-CFA stimulation and synovial tissues and spleens were removed to analyze GM3S mRNA (n = 5 per group). A. mRNA in synovial tissue. B. mRNA in spleen. Data shown are mean ± SEM. *P<0.05, compared with naïve WT mice.
Figure 4.
Phenotype of WT and GM3S−/− CIA mice.
CIA was induced in C57BL/6 WT and GM3S−/− mice (10–15 weeks old). Mice were immunized with chicken CII emulsified with CFA on days 0 and 21(n = 17 WT and n = 12 GM3S−/− mice). A. Cumulative incidence of arthritis. B. Arthritis score with CII-CFA. C. Photomicrographs show HE-stained paraffin sections of the right hind limbs of naïve, CIA WT, and CIA GM3S−/− mice at day 35 of the study. Scale bars = 200 µm D. Histological scores on day 35 after primary immunization with CII-CFA (n = 5 per group). E. Serum IL-6 levels in mice on day 25 after primary immunization with CII-CFA (n = 5 per group). F. Serum levels of total IgG, IgG1, IgG2a, IgG2b, and IgG3 anti-chicken CII antibodies with CII-CFA on day 35 after primary immunization (n = 5 per group). Data shown are mean ± SEM. *P<0.05, **P<0.01 compared to WT mice.
Table 1.
Onset of CIA from primary immunization.
Figure 5.
Immune response of T cells in WT and GM3S−/− mouse CIA models. A.
CD4+, CD8+, B220+, and CD11b+ T cell contents of iLNs in WT and GM3S−/− mice on day 7 after immunization with CII-CFA (n = 3 per group). B. The Th17 cell content in CD4+ T cells in mouse iLNs (n = 3 per group). Data shown are mean ± SEM. *P<0.05, compared to WT mice.
Figure 6.
T-cell immune response following anti-CD3 antibody stimulation.
Serum levels of IL-17, IL-4, IFNγ, IL-6, and TNFα at 1.5 h after intraperitoneal administration of 20 µg anti-CD3 antibody (n = 5 per group). Data shown are mean ± SEM. *P<0.05, compared to WT mice.