HOMING EXPRESSION MOLECULES RANK, CXCR4 AND AXL ARE MODIFIED BY INDOMETHACIN TREATMENT IN LANGERHAN CELL HISTIOCYTOSIS AND IN VITRO DENDRITIC CELLS

MARIA CATALINA LAVA; DENISE RISNIK; CINTHIA MARIEL OLEXEN; DIEGO ALFREDO ROSSO; ANDREA EMILSE ERRASI; EUGENIO ANTONIO CARRERA SILVA

San Luis

Congreso; LXXI Reunión Anual de la Sociedad Argentina de Inmunología; 2023

Langerhans cells histiocytosis (LCH) is a rare disease with an abnormal accumulation of pathological Langerhans cells (LC) in almost any tissue. When the bone is compromised, Indomethacin, a non-selective COX inhibitor (NSAID) is an effective treatment. Nevertheless, the specific mechanism of action involved in this therapeutic benefit is not defined. We hypothesized that Indomethacin restrain the homing and migration of pathological LC and/or their precursors to the bone. We analyzed the effect of indomethacin on the expression of homing receptors CCR1, CXCR4, AXL and RANK in monocytes, in-vitro differentiated dendritic cells (DC) and inflammatory Langerhans like “LC-like” cells. Moreover, to determine if this effect is extended to another NSAID, we compared it with Ibuprofen. Finally, we have also measured the expression of AXL, RANK and CXCR4 in monocytes obtained from LCH patient’s vs controls and before and after indomethacin treatment. CD14+ monocytes from Peripheral Blood Mononuclear cells of healthy volunteers were used as precursor cells, and conventional DC (GM-CSF + IL-4) and inflammatory Langerhans like cells “LC-like” (IL-4 + GM-CSF + TNFα + TGFβ + dexamethasone) were in-vitro differentiated from monocytes. The treatment was performed with 100uM of Indomethacin or Ibuprofen or vehicle. qPCR and flow cytometry assays were performed to evaluate their effect on gene expression and proteins, respectively. Indomethacin significantly reduced RNA expression of RANK (N=6, P=0.015), AXL (N=6, P=0.031) and CCR1 (N=8, P= 0.007) in conventional DC. AXL was reduced in both conventional DC and “LC-like” cells confirmed by qPCR and flow cytometry. Treatment of monocytes with Indomethacin also reduced the expression of AXL (N=9, P=0.004) and CXCR4 (N=6, P=0.031), measured by flow cytometry, meanwhile, when monocytes were treated with Indomethacin, RNA expression of RANK was upregulated (N=9, P=0.003). Interestingly, when the cells were treated with Ibuprofen, conventional DC showed a trend reduction in the RNA expression of CCR1 (N=4, P=0.062) and RANK (N=4, P=0.062). Monocyte treatment with ibuprofen does not modify AXL expression, but significantly reduces CXCR4 levels measured by flow cytometry (N=6, P=0.031). Interestingly, preliminary results with AXL (N=6), RANK (N=5) and CXCR4 (N=6) showed a decrease in their expression in monocytes from patients with bone LCH under indomethacin treatment. Indomethacin affects homing molecules on in-vitro differentiated DC, “LC-like” cells, and their precursors, with some specific differences when compared with Ibuprofen. Importantly, patients with bone compromise and under Indomethacin treatment also showed a reduction of these molecules in monocytes suggesting a possible mechanism involved in its therapeutic benefit.