An updated model for maternal separation with early weaning to study early life stress on immune competency

Epidemiological data suggests early life stress (ELS) has negative effects on long-term health and a role in immune-mediated diseases. A significant challenge of studying ELS in the basic sciences has been difficulty developing a reliable mouse model with robust, reproducible stress effects. Although variations of maternal separation in rodents have been published, to date no mouse variant has demonstrated predictable effects on peripheral corticosterone. We describe an updated version of the maternal separation with early weaning (MSEW) paradigm and investigate how psychosocial stress during a defined perinatal window impacts the cytokine profile of select primary and secondary lymphoid tissues. Pups were produced through in-house breeding procedures and subjected to our modified MSEW procedure. Euthanasia occurred at postnatal day (PD) 14 or 21 for blood collection via cardiac puncture. Serum corticosterone and catecholamine levels were detected using commercially available ELISA. Corticosterone was significantly increased in stressed males at PD21 (P< 0.001). Thymocytes of stressed females showed increased secretion of IL-10 (P< 0.001), while stress males exhibited elevated IL-17A (P=0.003) and IL-10 (P< 0.001). Splenocytes of stressed males produced decreased levels of IFN-gamma (P< 0.001) relative to the control. This pilot study demonstrates our updated MSEW model is capable of inducing increased peripheral corticosterone in C57BL/6 pups at PD21 and shows ELS skews cytokine production within select lymphoid tissues at PD21. Preliminary data also suggests sex-dependent effects of ELS on secretion of cytokines critical for T helper 17 and regulatory T cell phenotypes.