Effects of Progesterone and Estradiol Sex Hormones on the Release of Microparticles by RAW 264.7 Macrophages Stimulated by Poly(I:C)

Abstract

Microparticles (MPs) are small membrane-bound vesicles that display proinflammatory and prothrombotic properties. These particles can be released by macrophages stimulated by ligands of the Toll-like receptors (TLRs) in a process that depends on nitric oxide (NO) production. Since sex hormones can modulate macrophage responses, we investigated the effects of progesterone and estradiol on macrophage particle release in vitro, comparing the responses with those induced by the glucocorticoid dexamethasone. As a model system for particle release, RAW 264.7 cells were stimulated in vitro with poly(I:C), a ligand of TLR3. Microparticles were measured by flow cytometry, while NO was measured by the Griess reaction. As the results of these studies showed, progesterone but not estradiol can block particle release by RAW264.7 cells treated with poly(I:C); dexamethasone was also active. Furthermore, while progesterone and dexamethasone inhibited NO production under the same culture conditions, neither agent blocked the production of particles stimulated by the NO donors dipropylenetriamine NONOate {(z)-1-[N-(3-aminopropyl)-N-(3-ammoniopropyl)amino] diazen-1-ium-1,2-diolate} and (z)-1-[(2-aminoethyl)-N-(2-ammonioethyl)amino] diazen-1-ium-1,2-diolate. Studies using RU486 to assess the role of hormone receptors indicated that while this agent blocked the inhibition of particle and NO production by dexamethasone, it did not affect the inhibition by progesterone. Together, these results indicate that progesterone but not estradiol can inhibit particle release by stimulated macrophages and suggest a mechanism that may contribute to the immunomodulatory effects of this sex hormone.

Annexin A1 mediates the anti‐adhesive effects of dexamethasone during the cell–cell interaction between the all‐trans retinoic acid‐treated acute promyelocytic leukemic cells and endothelial cells

“…The effect of dexamethasone on the release of MPs from neutrophils has been rarely studied. In contrast to our results, Pisetsky and Spencer [2011] reported that dexamethasone was able to inhibit the release of MPs by macrophages. The reason of this controversy is still not clear and needs further study.…”

Circulating microparticles: square the circle

“…Increased MP output is also driven by signals transduced through specific activating receptors, such as the purinergic receptor P2X on monocytes and neutrophils, thrombin receptors on platelets, and Toll-like receptor 4 (TLR4) on dendritic cells [118]. The level of MPs in human plasma can increase or decrease in response to different hormones, such as progesterone, estradiol, estrogen, insulin and others [119-121]. For example, low levels of estrogen in the blood are associated with increased microvesiculation and MP release [122].…”

Progesterone-based compounds affect immune responses and susceptibility to infections at diverse mucosal sites

“…39 Similarly, P4 treatment of the macrophage cell line RAW264.7 inhibits TLR3, TLR4, and TLR9 signaling in response to Poly I:C, LPS, or CpG DNA, respectively, and downstream IL-6 and nitric oxide production. 35,44 In vitro treatment with P4 alters the phenotype of murine macrophages by inducing the expression of Fizz-1 and YM-1, two markers of alternatively activated macrophages, and decreasing the production of nitric oxide following LPS stimulation. 45 In murine bone marrow-derived macrophages treated with LPS, P4 but not LNG decreases nitric oxide production and the ability to lyse Leishmania intracellular parasites.…”