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Updated: Jun 1, 2026
Modeling Encephalopathy of Prematurity Using Prenatal Hypoxia-ischemia with Intra-amniotic Lipopolysaccharide in Rats
Published on: November 20, 2015
Developmental regulation of the neuroinflammatory responses to LPS and/or hypoxia-ischemia between preterm and term
Marie-Elsa Brochu1, Sylvie Girard, Karine Lavoie
1Child Neurology Laboratory, Université de Sherbrooke, Canada Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, 3001 12eme avenue Nord, J1H5N4 Sherbrooke, Canada.
Insights
Hypoxia-ischemia (HI) and lipopolysaccharide (LPS) exposure cause distinct brain inflammatory responses in preterm-like and term-like developing brains. Understanding these age-dependent immune reactions is crucial for developing neuroprotective strategies against perinatal brain damage.
Area of Science:
- Neuroscience
- Immunology
- Developmental Biology
Background:
- Perinatal brain damage in newborns is linked to hypoxia-ischemia (HI), pathogen exposure, and inflammation.
- The impact of varying pro- and anti-inflammatory cytokine ratios on brain development is not well understood.
Purpose of the Study:
- To investigate age-dependent neuroinflammatory responses to HI and LPS in developing rat brains.
- To compare cytokine expression in preterm-like (postnatal day 1) and term-like (postnatal day 12) brain development.
Main Methods:
- Utilized rat models of perinatal brain damage induced by HI and/or LPS exposure.
- Assessed cytokine expression at P1 and P12, representing preterm and term brain development.
- Analyzed blood-brain barrier (BBB) integrity and immune cell infiltration.
Main Results:
- Preterm-like brains (P1) showed down-regulated anti-inflammatory cytokines and primarily IL-1β release.
- Term-like brains (P12) exhibited up-regulated anti-inflammatory cytokines and increased IL-1β and TNF-α.
- HI and LPS+HI at P12 led to BBB leakage and immune cell recruitment, unlike LPS alone.
Conclusions:
- HI and LPS+HI induce significant neuroinflammation, with combined LPS+HI triggering the strongest response.
- Age-dependent variations in inflammatory profiles (preterm vs. term) may explain differential brain lesion patterns.
- Considering brain and immune system maturation is vital for developing effective neuroprotective therapies.
Background:
Preterm and term newborns are at high risk of brain damage as well as subsequent cerebral palsy and learning disabilities. Indeed, hypoxia-ischemia (HI), pathogen exposures, and associated intracerebral increase of pro-inflammatory cytokines have all been linked to perinatal brain damage. However, the developmental effects of potential variations of pro- and anti-inflammatory cytokine ratios remain unknown.
Methods:
Using rat models of perinatal brain damage induced by exposures to lipopolysaccharide (LPS) and/or HI at distinct levels of maturity, we compared cytokine expression at stages of cerebral development equivalent to either preterm (postnatal day 1, P1) or term (P12) newborns.
Results:
At P1, expression of anti-inflammatory cytokine within the brain was either not modulated (IL-6, IL-10) or down-regulated (IL-1ra, TGF-β1) by HI, LPS or LPS+HI. In contrast, there was at P12 an up-regulation of all anti-inflammatory cytokines studied in HI or LPS+HI condition, but not after LPS exposure. Interestingly, IL-1β was the main pro-inflammatory cytokine up-regulated moderately at P1, and strongly at P12, with a weak co-expression of TNF-α observed mainly at P12. These age-dependant inflammatory reactions were also accompanied, under HI and LPS+HI conditions, at P12 only, by combined: (i) expression of chemokines CINC-1 and MCP-1, (ii) blood-brain barrier (BBB) leakage, and (iii) intracerebral recruitment of systemic immune cells such as neutrophils. In contrast, sole LPS induced IL-1β responses mainly within white matter at P1 and mainly within gray matter at P12, that were only associated with early MCP-1 (but no CINC-1) induction at both ages, without any recruitment of neutrophils and CD68+ cells.
Conclusion:
HI and LPS+HI induce pro-inflammatory oriented immune responses in both preterm and term like brains, with a maximal inflammatory response triggered by the combination of LPS+HI. The profile of these neuroinflammatory responses presented striking variations according to age: no or down-regulated anti-inflammatory responses associated with mainly IL-1β release in preterm-like brains (P1), in sharp contrast to term-like brains (P12) presenting stronger anti-and pro-inflammatory responses, including both IL-1β and TNF-α releases, and BBB leakage. These developmental-dependant variations of neuroinflammatory response could contribute to the differential pattern of brain lesions observed across gestational ages in humans. This also highlights the necessity to take into consideration the maturation stage, of both brain and immune systems, in order to develop new anti-inflammatory neuroprotective strategies.
