457 - Modulation of Interleukin (IL) -1 and -6 receptors prevents mouse preterm birth and newborn death due to a viral mimic.

Publication Number: 2445.457

David M.. Olson, University of Alberta Faculty of Medicine and Dentistry, Edmonton, AB, Canada; Madeline G. Osman, University of Alberta Faculty of Medicine and Dentistry, Edmonton, AB, Canada; Junyoung Yang, University of Alberta Faculty of Medicine and Dentistry, Edmonton, AB, Canada; Kelycia B. Leimert, University of Alberta Faculty of Medicine and Dentistry, Edmonton, AB, Canada; Sylvain Chemtob, CHU Sainte Justine, Montreal, PQ, Canada

Background: Perinatal viral infection poses significant immediate and life-long health threats to newborns. There are no treatments to block the viral inflammation. Polyinosinic:polycytidylic acid (Poly I:C), a dsRNA mimic, binds to Toll-Like Receptor 3 and stimulates cytokine synthesis, especially IL-1and IL-6. We developed a murine perinatal model treated with Poly I:C that leads to preterm birth (PTB) and newborn demise.

Objective: Our objective was to test the mitigating effects of the short peptide allosteric antagonists for the IL-1 and -6 receptors, rytvela and HSJ639, separately and in combination. We hypothesized that combined rytvela and HSJ639 would better protect newborn mice against Poly I:C harm than either alone.

Design/Methods: Timed pregnant CD-1 mice received injections of Poly I:C (10 mg/kg/dose, i.p.) on gestational days (GD) 16.5 and 17, or saline as control. Poly I:C-exposed dams (n = 7-12/group) were assigned to no treatment, rytvela (1 mg/kg/dose), HSJ639 (1.3 mg/kg/dose), or combination groups (0.5 mg/kg/dose rytvela + 0.6 mg/kg/dose HSJ639). Treatments were administered subcutaneously at GD16.5 +2h, GD17 +2h, GD17.5, and GD18. Birth timing, gestation length, and litter size were recorded. Neonates were monitored for survival on postnatal days (PND) 1, 3, 5, and 7. On PND7, lung tissues were collected for RNA analysis of IL-1β, IL-6, TNF-α, and CCL2.

Results: Poly I:C induced PTB in 25% of dams and death in 22% of the neonates by PND7. Rytvela reduced PTB to 10%, HSJ639 to 9%, and combined completely prevented PTB. Neonatal mortality was significantly reduced in all treatment groups: rytvela 10%, HSJ639 2.7%, and combined 1.5%, n = 81-148 pups/group, p< 0.0001. In lung tissue, Poly I:C stimulated increases in mRNA abundance of IL-1: 14%, IL-6: 428%, TNF: 42%, and CCL2: 261%. IL-6 increases were inhibited by rytvela: 84%, HSJ639: 93%, and combined: 89%, p< 0.05, n = 3-8.

Conclusion(s): Poly I:C stimulated 4-fold increases in IL-6 in lung and a much smaller increase in IL-1 along with increases in TNF and CCL2. These were associated with PTB and loss of several pups by PND7. Rytvela, HSJ639, and combination treatments were effective in significantly reducing IL-6 mRNA abundance (and other cytokines) and protecting against PTB and newborn mortality. Combined treatment was best for both conditions with HSJ639 better than rytvela. IL-6 is a dominant cytokine with Poly I:C-induced perinatal harm. Combined treatment offers the greatest protection, and clinical trials should be initiated.

Funding: CIHR, Alberta Innovates

Effect of Poly I:C plus interventions on newborn pup survival to PND7
Survival of newborn mouse pups to PND7 following maternal treatment with saline, Poly I:C alone, or Poly I:C plus rytvela, HSJ639, or combined rytvela + HSJ639.