Abstract TMP32: Post-Stroke Systemic Inflammation: Immunomodulation by Progesterone and Vitamin D Hormone

Abstract

Introduction: Post-stroke systemic inflammation due to in-hospital infections increases patient morbidity and mortality. We examined the immunomodulatory effects of progesterone (P4) either alone or in combination with vitamin D hormone (VDH) on post-stroke systemic inflammation-induced peripheral immune dysfunction and functional deficits. Methods: Adult male Sprague-Dawley rats underwent transient middle cerebral artery occlusion/reperfusion (tMCAO) or sham surgery. Delayed systemic inflammation was induced by injections of lipopolysaccharide (LPS; 50 μg/kg; IP) at 24, 28 and 32 h post-occlusion. P4 (8 mg/kg; IP) and VDH (1 μg/kg; IP) were given 5 min prior to reperfusion followed by SC injections on days 1, 2 and 3 post-stroke. Power analysis specified a sample size of 6 rats/group to detect a 30% difference between treatment groups with a power of 80% at alpha 0.05. There were 6 groups (n=6/gp): 1) Sham + vehicle (SHAM); 2) tMCAO + vehicle (VEH); 3) tMCAO + vehicle + LPS (VEH + LPS); 4) tMCAO + LPS + P4 (P4); 5) tMCAO + LPS + VDH (VDH); 6) tMCAO + LPS + P4 + VDH (P4 + VDH). At day 4 post-stroke, rats were tested on spontaneous locomotor activity, grip strength and sensory neglect; peripheral immune dysfunctions were assessed by flow cytometric analysis of subsets of immune cells in blood, spleen and thymus. We measured markers of neuronal inflammation (GFAP, Iba-1, IL-6), apoptosis (cleaved caspase-3, TUNEL), and endoplasmic reticulum (ER) stress (PERK, eIF2α, CHOP) in brain. Data were analyzed using ANOVA with the Tukey-HSD post hoc test. Statistical significance was set at p <0.05. Results: The worst stroke outcomes were seen in the VEH + LPS group. Peripheral immune dysfunctions revealed by flow cytometry were significantly ( p <0.05) restored by both P4 and VDH monotherapy. While P4 and VDH individually improved functional deficits, neuronal inflammation, apoptosis and ER stress induced by post-stroke systemic inflammation, the combination of P4 + VDH improved outcomes significantly ( p <0.05) more than monotherapy. Conclusions: Our findings may have translational relevance because the current standard of care for stroke and post-stroke infections is largely ineffective and our P4+VDH combination therapy may hold promise for stroke therapeutics.