Intra-amniotic LPS causes acute neuroinflammation in preterm rhesus macaques.
Chorioamnionitis is associated with an increased risk of brain injury in preterm neonates. Inflammatory changes in brain could underlie this injury. Here, we evaluated whether neuroinflammation is induced by chorioamnionitis in a clinically relevant model.



Rhesus macaque fetuses were exposed to either intra-amniotic (IA) saline, or IA lipopolysaccharide (LPS) (1 mg) 16 or 48 h prior to delivery at 130 days (85 % of gestation) (n = 4-5 animals/group). We measured cytokines in the cerebrospinal fluid (CSF), froze samples from the left brain for molecular analysis, and immersion fixed the right brain hemisphere for immunohistology. We analyzed the messenger RNA (mRNA) levels of the pro-inflammatory cytokines IL-1β, CCL2, TNF-α, IL-6, IL-8, IL-10, and COX-2 in the periventricular white matter (PVWM), cortex, thalamus, hippocampus, and cerebellum by RT-qPCR. Brain injury was assessed by immunohistology for myelin basic protein (MBP), IBA1 (microglial marker), GFAP (astrocyte marker), OLIG2 (oligodendrocyte marker), NeuN (neuronal marker), CD3 (T cells), and CD14 (monocytes). Microglial proliferation was assessed by co-immunostaining for IBA1 and Ki67. Data were analyzed by ANOVA with Tukey's post-test.



IA LPS increased mRNA expression of pro-inflammatory cytokines in the PVWM, thalamus, and cerebellum, increased IL-6 concentration in the CSF, and increased apoptosis in the periventricular area after 16 h. Microglial proliferation in the white matter was increased 48 h after IA LPS.



LPS-induced chorioamnionitis caused neuroinflammation, microglial proliferation, and periventricular apoptosis in a clinically relevant model of chorioamnionitis in fetal rhesus macaques. These findings identify specific responses in the fetal brain and support the hypothesis that neuroinflammatory changes may mediate the adverse neurodevelopmental outcomes associated with chorioamnionitis.
Division of Neonatology and Pulmonary Biology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave, Cincinnati, OH, 45229, USA.
Augusto F
AF
Schmidt
Division of Neonatology and Pulmonary Biology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave, Cincinnati, OH, 45229, USA.
Paranthaman S
PS
Kannan
Division of Immunobiology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
Claire A
CA
Chougnet
Department of Anesthesia, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.
Steve C
SC
Danzer
California National Primate Research Center and Department of Pediatrics and Cell Biology and Human Anatomy, University of California, Davis, CA, USA.
Lisa A
LA
Miller
Division of Neonatology and Pulmonary Biology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave, Cincinnati, OH, 45229, USA.
Alan H
AH
Jobe
Division of Neonatology and Pulmonary Biology, Cincinnati Children's Hospital Medical Center, 3333 Burnet Ave, Cincinnati, OH, 45229, USA. suhas.kallapur@cchmc.org.
Suhas G
SG
Kallapur
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D001921:Brain / Q000187:drug effects / Q000473:pathology; D002135:Calcium-Binding Proteins; D002821:Chorioamnionitis / Q000139:chemically induced* / Q000473:pathology; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000378:metabolism; D005260:Female; D019394:Ki-67 Antigen / Q000378:metabolism; D008070:Lipopolysaccharides / Q000633:toxicity*; D008253:Macaca mulatta; D008840:Microfilament Proteins; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism; D004676:Myelin Basic Protein / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000139:chemically induced*; D000071876:Prostaglandin-E Synthases / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors
C112986:AIF1 protein, human; D002135:Calcium-Binding Proteins; D016207:Cytokines; D004268:DNA-Binding Proteins; D019394:Ki-67 Antigen; D008070:Lipopolysaccharides; D008840:Microfilament Proteins; D004676:Myelin Basic Protein; D009419:Nerve Tissue Proteins; D012333:RNA, Messenger; D051546:Cyclooxygenase 2; D000071876:Prostaglandin-E Synthases
Apoptosis; Brain injury; Chorioamnionitis; Cytokines; Microglia; Periventricular leukomalacia; Prematurity