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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS, RESULTS. Meshes: 3T3 Cells, Animals, Blotting, Northern, Fibroblasts, Fluorescent Antibody Technique, Gene Expression Regulation, Hematopoiesis, Extramedullary, Hematopoietic Stem Cells, Humans, Immunohistochemistry, Immunosorbent Techniques, Interleukin-6, Liver, Membrane Proteins, Mice, Mice, Transgenic, RNA, Messenger, Receptors, Interleukin-6, Solubility, Spleen, Stem Cell Factor.
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Do interleukin-6 and the soluble interleukin-6 receptor induce stem cell factor and Flt-3L expression in vivo and in vitro? Context: We recently established transgenic animals expressing either interleukin-6 (IL-6) or the soluble IL-6 receptor (sIL-6R) alone, or both components, IL-6 and the sIL-6R, in the liver. This animal model demonstrated that the expression of IL-6 in combination with its sIL-6R led to extramedullary expansion of hematopoietic progenitor cells in the spleen and liver. We studied other relevant hematopoietic cytokines involved in the IL-6/sIL-6R-induced stimulation of hematopoiesis. Using immunohistochemistry, we showed that cell-associated stem cell factor (SCF) and Flt-3L expression were upregulated in liver and spleen only in double transgenic mice but not in IL-6 or sIL-6R single transgenic animals. Moreover, on murine NIH/3T3 fibroblasts and on human primary forskin fibroblasts, stimulation with the IL-6/sIL-6R complex, and to a lesser extent with IL-6 alone, led to induction of cellular SCF and Flt-3L expression. When human HTB-158 fibroblasts were stimulated with the IL-6/sIL-6R complex and subsequently cocultured with human umbilical cord CD34(+) cells, a significant upregulation in colony growth was found.
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We showed that IL-6 in combination with its soluble receptor stimulates cellular SCF and Flt-3L expression in vivo and in vitro. Cellular upregulation of SCF and Flt-3L by IL-6/sIL-6R might be used for the development of new stroma cell systems for ex vivo expansion of hematopoietic progenitor cells. Final Decision: yes