Early Neuroprotective Effects of Bovine Lactoferrin Associated with Hypothermia after Neonatal Brain Hypoxia-Ischemia in Rats.

Neonatal hypoxic-ischemic (HI) encephalopathy (HIE) in term newborns is a leading cause of mortality and chronic disability. Hypothermia (HT) is the only clinically available therapeutic intervention; however, its neuroprotective effects are limited. Lactoferrin (LF) is the major whey protein in milk presenting iron-binding, anti-inflammatory and anti-apoptotic properties and has been shown to protect very immature brains against HI damage. We hypothesized that combining early oral administration of LF with whole body hypothermia could enhance neuroprotection in a HIE rat model. Pregnant Wistar rats were fed an LF-supplemented diet (1 mg/kg) or a control diet from (P6). At P7, the male and female pups had the right common carotid artery occluded followed by hypoxia (8% O2 for 60') (HI). Immediately after hypoxia, hypothermia (target temperature of 32.5-33.5 °C) was performed (5 h duration) using Criticool®. The animals were divided according to diet, injury and thermal condition. At P8 (24 h after HI), the brain neurochemical profile was assessed using magnetic resonance spectroscopy (1H-MRS) and a hyperintense T2W signal was used to measure the brain lesions. The mRNA levels of the genes related to glutamatergic excitotoxicity, energy metabolism and inflammation were assessed in the right hippocampus. The cell markers and apoptosis expression were assessed using immunofluorescence in the right hippocampus. HI decreased the energy metabolites and increased lactate. The neuronal-astrocytic coupling impairments observed in the HI groups were reversed mainly by HT. LF had an important effect on astrocyte function, decreasing the levels of the genes related to glutamatergic excitotoxicity and restoring the mRNA levels of the genes related to metabolic support. When combined, LF and HT presented a synergistic effect and prevented lactate accumulation, decreased inflammation and reduced brain damage, pointing out the benefits of combining these therapies. Overall, we showed that through distinct mechanisms lactoferrin can enhance neuroprotection induced by HT following neonatal brain hypoxia-ischemia.

Low-molecular weight sulfated marine polysaccharides: Promising molecules to prevent neurodegeneration in mucopolysaccharidosis IIIA?

Mucopolysaccharidosis IIIA is a hereditary disease caused by mutations in the sulfamidase enzyme that participates in catabolism of heparan sulfate (HS), leading to HS fragment accumulation and multisystemic failure. No cure exists and death occurs around the second decade of life. Two low molecular weight highly sulfated compounds derived from marine diabolican and infernan exopolysaccharides (A5_3 and A5_4, respectively) with heparanase inhibiting properties were tested in a MPSIIIA cell line model, resulting in limited degradation of intracellular HS. Next, we observed the effects of intraperitoneal injections of the diabolican derivative A5_3 from 4 to 12 weeks of age on MPSIIIA mice. Brain metabolism and microstructure, levels of proteins and genes involved in MPSIIIA brain pathophysiology were also investigated. 1H-Magnetic Resonance Spectroscopy (MRS) indicated deficits in energetic metabolism, tissue integrity and neurotransmission at both 4 and 12 weeks in MPSIIIA mice, with partial protective effects of A5_3. Ex-vivo Diffusion Tensor Imaging (DTI) showed white matter microstructural damage in MPSIIIA, with noticeable protective effects of A5_3. Protein and gene expression assessments displayed both pro-inflammatory and pro-apoptotic profiles in MPSIIIA mice, with benefits of A5_3 counteracting neuroinflammation. Overall, derivative A5_3 was well tolerated and was shown to be efficient in preventing brain metabolism failure and inflammation, resulting in preserved brain microstructure in the context of MPSIIIA.

Dose-Dependent Neuroprotective Effects of Bovine Lactoferrin Following Neonatal Hypoxia-Ischemia in the Immature Rat Brain.

Injuries to the developing brain due to hypoxia-ischemia (HI) are common causes of neurological disabilities in preterm babies. HI, with oxygen deprivation to the brain or reduced cerebral blood perfusion due to birth asphyxia, often leads to severe brain damage and sequelae. Injury mechanisms include glutamate excitotoxicity, oxidative stress, blood-brain barrier dysfunction, and exacerbated inflammation. Nutritional intervention is emerging as a therapeutic alternative to prevent and rescue brain from HI injury. Lactoferrin (Lf) is an iron-binding protein present in saliva, tears, and breast milk, which has been shown to have antioxidant, anti-inflammatory and anti-apoptotic properties when administered to mothers as a dietary supplement during pregnancy and/or lactation in preclinical studies of developmental brain injuries. However, despite Lf's promising neuroprotective effects, there is no established dose. Here, we tested three different doses of dietary maternal Lf supplementation using the postnatal day 3 HI model and evaluated the acute neurochemical damage profile using 1H Magnetic Resonance Spectroscopy (MRS) and long-term microstructure alterations using advanced diffusion imaging (DTI/NODDI) allied to protein expression and histological analysis. Pregnant Wistar rats were fed either control diet or bovine Lf supplemented chow at 0.1, 1, or 10 g/kg/body weight concentration from the last day of pregnancy (embryonic day 21-E21) to weaning. At postnatal day 3 (P3), pups from both sexes had their right common carotid artery permanently occluded and were exposed to 6% oxygen for 30 min. Sham rats had the incision but neither surgery nor hypoxia episode. At P4, MRS was performed on a 9.4 T scanner to obtain the neurochemical profile in the cortex. At P4 and P25, histological analysis and protein expression were assessed in the cortex and hippocampus. Brain volumes and ex vivo microstructural analysis using DTI/NODDI parameters were performed at P25. Acute metabolic disturbance induced in cortical tissue by HIP3 was reversed with all three doses of Lf. However, data obtained from MRS show that Lf neuroprotective effects were modulated by the dose. Through western blotting analysis, we observed that HI pups supplemented with Lf at 0.1 and 1 g/kg were able to counteract glutamatergic excitotoxicity and prevent metabolic failure. When 10 g/kg was administered, we observed reduced brain volumes, increased astrogliosis, and hypomyelination, pointing to detrimental effects of high Lf dose. In conclusion, Lf supplementation attenuates, in a dose-dependent manner, the acute and long-term cerebral injury caused by HI. Lf reached its optimal effects at a dose of 1 g/kg, which pinpoints the need to better understand effects of Lf, the pathways involved and possible harmful effects. These new data reinforce our knowledge regarding neuroprotection in developmental brain injury using Lf through lactation and provide new insights into lactoferrin's neuroprotection capacities and limitation for immature brains.