Identification of novel pro-survival factors in the brain is paramount for developing neuroprotective therapies. The multifunctional S100 family proteins have important roles in many human diseases and are also upregulated by brain injury. However, S100 functions in the nervous system remain unclear. Here we show that the S100A4 protein, mostly studied in cancer, is overexpressed in the damaged human and rodent brain and released from stressed astrocytes. Genetic deletion of S100A4 exacerbates neuronal loss after brain trauma or excitotoxicity, increasing oxidative cell damage and downregulating the neuroprotective protein metallothionein I+II. We identify two neurotrophic motifs in S100A4 and show that these motifs are neuroprotective in animal models of brain trauma. Finally, we find that S100A4 rescues neurons via the Janus kinase/STAT pathway and, partially, the interleukin-10 receptor. Our data introduce S100A4 as a therapeutic target in neurodegeneration, and raise the entire S100 family as a potentially important factor in central nervous system injury.

Antenatal infection (i.e., chorioamnionitis) is an important risk factor for adverse neurodevelopmental outcomes after preterm birth. Destructive and developmental disturbances of the white matter are hallmarks of preterm brain injury. Understanding the temporal effects of antenatal infection in relation to the onset of neurological injury is crucial for the development of neurotherapeutics for preterm infants. However, these dynamics remain unstudied. Time-mated ewes were intra-amniotically injected with lipopolysaccharide at 5, 12, or 24 h or 2, 4, 8, or 15 days before preterm delivery at 125 days gestational age (term ~ 150 days). Post mortem analyses for peripheral immune activation, neuroinflammation, and white matter/neuronal injury were performed. Moreover, considering the neuroprotective potential of erythropoietin (EPO) for perinatal brain injury, we evaluated (phosphorylated) EPO receptor (pEPOR) expression in the fetal brain following LPS exposure. Intra-amniotic exposure to this single bolus of LPS resulted in a biphasic systemic IL-6 and IL-8 response. In the developing brain, intra-amniotic LPS exposure induces a persistent microgliosis (IBA-1 immunoreactivity) but a shorter-lived increase in the pro-inflammatory marker COX-2. Cell death (caspase-3 immunoreactivity) was only observed when LPS exposure was greater than 8 days in the white matter, and there was a reduction in the number of (pre) oligodendrocytes (Olig2- and PDGFRα-positive cells) within the white matter at 15 days post LPS exposure only. pEPOR expression displayed a striking biphasic regulation following LPS exposure which may help explain contradicting results among clinical trials that tested EPO for the prevention of preterm brain injury. We provide increased understanding of the spatiotemporal pathophysiological changes in the preterm brain following intra-amniotic inflammation which may aid development of new interventions or implement interventions more effectively to prevent perinatal brain damage.

Optimal nutrition is important after preterm birth to facilitate normal brain development. Human milk is rich in sialic acid and preterm infants may benefit from supplementing formula with sialyllactose to support neurodevelopment. Using pigs as models, we hypothesized that sialyllactose supplementation improves brain development after preterm birth. Pigs (of either sex) were delivered by cesarean section at 90% gestation and fed a milk diet supplemented with either an oligosaccharide-enriched whey with sialyllactose (n = 20) or lactose (n = 20) for 19 days. Cognitive performance was tested in a spatial T-maze. Brains were collected for ex vivo magnetic resonance imaging (MRI), gene expression, and sialic acid measurements. For reference, term piglets (n = 14) were artificially reared under identical conditions and compared with vaginally born piglets naturally reared by the sow (n = 12). A higher proportion of sialyllactose supplemented preterm pigs reached the T-maze learning criteria relative to control preterm pigs (p < 0.05), and approximated the cognition level of term reference pigs (p < 0.01). Furthermore, supplemented pigs had upregulated genes related to sialic acid metabolism, myelination, and ganglioside biosynthesis in hippocampus. Sialyllactose supplementation did not lead to higher levels of sialic acid in the hippocampus or change MRI endpoints. Contrary, these parameters were strongly influenced by postconceptional age and postnatal rearing conditions. In conclusion, oligosaccharide-enriched whey with sialyllactose improved spatial cognition, with effects on hippocampal genes related to sialic acid metabolism, myelination, and ganglioside biosynthesis in preterm pigs. Dietary sialic acid enrichment may improve brain development in infants.

Erythropoietin, a member of the type 1 cytokine superfamily, controls proliferation and differentiation of erythroid progenitor cells through binding to and dimerization of the erythropoietin receptor. Both erythropoietin and its receptor are also expressed in the central nervous system, where they are involved in tissue protection. However, the use of erythropoietin as a neuroprotective agent may be hampered by its erythropoietic activity. Therefore, developing non-haematopoietic erythropoietin mimetics is important. Based on the crystal structure of the complex of erythropoietin and its receptor, we designed a peptide, termed Epotris, corresponding to the C α-helix region (amino-acid residues 92–111) of human erythropoietin. The peptide specifically bound to the erythropoietin receptor and promoted neurite outgrowth and survival of primary neurons with the same efficiency as erythropoietin, but with 10³-fold lower potency. Knockdown of the erythropoietin receptor or interference with its downstream signalling inhibited the Epotris-induced neuritogenic and pro-survival effect. Similarly to erythropoietin, Epotris penetrated the blood–brain barrier. Moreover, treatment with the peptide attenuated seizures, decreased mortality and reduced neurodegeneration in an in vivo model of kainic acid-induced neurotoxicity. In contrast to erythropoietin, Epotris did not stimulate erythropoiesis upon chronic administration. Thus, Epotris is a novel neuroprotective non-haematopoietic erythropoietin mimetic that may offer new opportunities for the treatment of neurological disorders.