Fig. 5.

NEU3 upregulates IL-6 and IL-1β, IL-6 upregulates NEU3, and Neu3^−/− mice have less bronchoalveolar lavage (BAL) IL-6 after bleomycin treatment. A and B: human peripheral blood mononuclear cells (PBMCs) were cultured with recombinant human NEU3 and culture supernatants were assayed by ELISA for IL-6 (A) and IL-1β (B). Values are means ± SE, n = 3. C and D: human monocytes (C) and human lymphocytes (D) were cultured in human recombinant IL-6 and cells were assayed for NEU 1–4 expression by flow cytometry. Values are means ± SE, n = 3. *P < 0.05; **P < 0.01; ***P < 0.001 (2-way ANOVA, Bonferroni’s test). E and F: human monocytes (E) and human lymphocytes (F) were cultured in human recombinant IL-1β and cells were assayed for NEU1–4 expression by flow cytometry. MFL, median fluorescence intensity. Values are means ± SE, n = 3. G and H: BAL (G) and serum (H) from the indicated mouse groups were collected at day 21 and assayed by ELISA for IL-6. Values are means ± SE, n = 6 except for bleomycin-treated C57BL/6, where n = 9. #P < 0.05 (t test). Bleo, bleomycin. I and J: BAL (I) and serum (J) from the indicated mouse groups were collected at day 21 and assayed by ELISA for IL-1β. Values are means ± SE, n = 6 except for bleomycin-treated C57BL/6, where n = 9. For G and I, IL-6 and IL-1β were measured as μg per mg of total BAL protein, and values were normalized to the C57BL/6 saline mean values (4.6 ± 0.8 μg IL-6/mg BAL protein and 1.8 ± 0.3 μg IL-1β/mg BAL protein). For H and J, values were measured as pg/ml of serum and were similarly normalized to the C57BL/6 saline mean values (8.1 ± 2.5 pg IL-6/mL serum and 2.8 ± 0.5 pg IL-1β/mL serum).