These data infer that ML is able to activate a positive feedback loop enrolling both IL-10 and CD163. Since IDO activity in human monocytes is known to increase as a result of ML exposure , it can be speculated that, in LL, the regulatory adaptive immune response
is induced by innate IL-10, CD163, and IDO-mediated pathways. The effect of the phagocytosis pathway blockade on CD163 expression was investigated by testing Ferrostatin-1 concentration whether inert beads were able to induce CD163 expression but, in this scenario, no effect was observed (data not shown). To verify whether live (MOI 5: 1) or dead (MOI 5: 1) ML colocalizes with CD163 in human monocytes, flow cytometry analysis was performed to ascertain the percentage of double-positive CD163 — ML cells. Although no statistical difference could be found, live mycobacteria colocalized more closely with CD163 (32.71 ± 9.04%) than dead ML (17.75 ± 1.47%) (Fig. 5A). Via flow cytometry, it was verified whether the addition of cytochalasin B (cyt B) could modify the expression
of CD163 on the monocytic surface. Figure 5B shows that Cyt B decreased ML-induced CD163 expression, inferring that bacterial phagocytosis is an important mechanism involved in CD163 induction. Fulvestrant in vitro Accordingly, it was then evaluated if a CD163 blockade could in any way affect mycobacterium uptake. As detected by flow cytometric analysis, CD163-neutralizing antibody decreased ML internalization by monocytes in both early (2 h) and later (16 and 24 h) incubation times as compared to isotype pretreated (Fig. 5C and D) and nontreated (Fig. 5D) monocytes. Time course experiments showed that ML phagocytosis occurs in a similar manner
(about 50% of infections) in nonpretreated and isotype-pretreated cells at the times analyzed. However, the bacterial association process in anti-CD163-preteated cells was more expressive in the shortest time slot (from 100% in ML + isotype versus 20.49 ± 3.250% in ML + neutralizing CD163 at 2 h, p < 0.0001) when compared with the later times (from 100% in ML + isotypee versus 62.27 ± 5.159% in ML + neutralizing CD163 at 16 h, p < 0.0001; and 45.31 ± 1.25% in ML + isotype versus 67.72 ± 1.13% in ML + neutralizing CD163 at 24 Histone demethylase h, p < 0.01). Additional assays were performed to confirm that the neutralization of CD163 affects ML internalization and not bacterial association alone. These results showed that neutralization with anti-CD163 blocked both bacterial adhesion and phagocytosis, indicating that the internalization process was more severely affected by this treatment than was bacterial binding (∼80% of inhibition of ML association and ∼88% of inhibition of ML internalization at 2 h; ∼40% of inhibition of ML association and ∼62% of inhibition of ML internalization at 16 h). In addition, HEK293 CD163 transfected cells were tested for their capacity to internalize mycobacteria.