Printed Poster | Session 1

065 – Immune Cell Activation: Not So Sexy

Timothy Friedman (1) – Isabelle Tottenham (1) – Bradley Kerr (2)
University of Alberta, Neuroscience and Mental Health Institute, Edmonton, Canada (1) – University of Alberta, Department Anesthesiology and Pain Medicine, Edmonton, Canada (2)

Multiple sclerosis (MS) is an inflammatory disease with a known sex bias towards females. The bias extends into symptomatology with women reporting higher rates of chronic neuropathic pain. Using the EAE model, we have recently described significant alterations in the profiles of the dorsal root ganglia, which include the nociceptive cells responsible for generating pain signals as well as transiently located immune cells. These alterations included large increases in miR-21a-5p (miR-21) in both female and male mice at onset of symptoms, an effect previously linked to MS immune pathology. Therefore, miR-21 may be implicated in immune cell activation. However, the rate or extent at which this occurs is unclear. Hypothesis: Female immune cells are intrinsically more sensitive to inflammatory signals. Methods: Female and male C57BL/6 mouse bone-marrow derived macrophages (BMDMs) were treated with escalating doses of tumor necrosis factor alpha (TNFa) for 24 hours in order to generate an inflammatory response. The state of macrophage activation was assessed by quantitative (qPCR; miR-21, Tlr7, Tlr8, Nlrp3, and Stat1) and semi-quantitative (ICC; iNOS, Arg1, CD45) methods. To isolate the effect of miR-21, identical cultures were transfected with miR-21 mimics (mirVana, ThermoFisher) before subsequent transfection with TNFa. Results: Preliminary data suggests that miR-21 is upregulated by TNFa exposure without compromising cell viability and the level of miR-21 upregulation is consistent with previous in vivo studies. We have confirmed that BMDMs are viable after miR-21 transfection and remain responsive to TNFa stimulation. Conclusion: Sex differences in the activation of the innate immune system is important in understanding how chronic neuropathic pain may arise in MS. Here we show that miR-21 expression is stimulated by TNFa exposure in vitro and that this shift in expression is associated with a more inflammatory phenotype. Peripheral immune cells are regularly exposed to TNFa in the course of EAE, therefore the increased miR-21 seen in previous work may be a result of this immune activation.

Bradley J. Kerr is also affiliated with the Department of Psychiatry (NRU) at the University of Alberta and the Department of Pharmacology at the University of Alberta.