PainRelief.com Interview with:
Prof. Dr. Halina Machelska
Department of Experimental Anesthesiology
Charité-Universitätsmedizin Berlin
Berlin, Germany

PainRelief.com:  What is the background for this study?

Response: Pathological pain such as pain resulting from nerve injury is often accompanied by inflammation. This is manifested by accumulation of immune cells, including macrophages, in the damaged tissue. Current research mostly emphasizes the role of these cells in the enhancement of pain. One of the suggested strategies in the basic research is to deplete immune cells from the affected tissue. However, several previous preclinical studies, including our own, have shown that this approach did not sufficiently decrease pain. We think that one of the reasons is that not all immune cells invading damaged tissue are detrimental and in fact, some are needed there to counteract pain.

Macrophages are very heterogeneous and they comprise at least two subpopulations, pro-inflammatory M1 and anti-inflammatory M2 macrophages. Our idea in this study was to promote the analgesic properties of macrophages. We took advantage of the cytokine interleukin-4 (IL-4) to switch macrophages from the M1 to the M2 state.