Cytokine production pattern of T lymphocytes in neonatal arterial ischemic stroke during the first month of life-a case study

Perinatal Azithromycin Provides Limited Neuroprotection in an Ovine Model of Neonatal Hypoxic-Ischemic Encephalopathy

BACKGROUND

Hypoxic-ischemic brain injury/encephalopathy affects about 1.15 million neonates per year, 96% of whom are born in low- and middle-income countries. Therapeutic hypothermia is not effective in this setting, possibly because injury occurs significantly before birth. Here, we studied the pharmacokinetics, safety, and efficacy of perinatal azithromycin administration in near-term lambs following global ischemic injury to support earlier treatment approaches.

METHODS

Ewes and their lambs of both sexes (n=34, 141-143 days) were randomly assigned to receive azithromycin or placebo before delivery as well as postnatally. Lambs were subjected to severe global hypoxia-ischemia utilizing an acute umbilical cord occlusion model. Outcomes were assessed over a 6-day period.

RESULTS

While maternal azithromycin exhibited relatively low placental transfer, azithromycin-treated lambs recovered spontaneous circulation faster following the initiation of cardiopulmonary resuscitation and were extubated sooner. Additionally, peri- and postnatal azithromycin administration was well tolerated, demonstrating a 77-hour plasma elimination half-life, as well as significant accumulation in the brain and other tissues. Azithromycin administration resulted in a systemic immunomodulatory effect, demonstrated by reductions in proinflammatory IL-6 (interleukin-6) levels. Treated lambs exhibited a trend toward improved neurodevelopmental outcomes while histological analysis revealed that azithromycin supported white matter preservation and attenuated inflammation in the cingulate and parasagittal cortex.

CONCLUSIONS

Perinatal azithromycin administration enhances neonatal resuscitation, attenuates neuroinflammation, and supports limited improvement of select histological outcomes in an ovine model of hypoxic-ischemic brain injury/encephalopathy.

The role of lymphocytes in neonatal encephalopathy

Neonatal encephalopathy is a syndrome characterised by abnormal neurological function often caused by a hypoxic insult during childbirth. Triggers such as hypoxia-ischaemia result in the release of cytokines and chemokines inducing the infiltration of neutrophils, natural killer cells, B cells, T cells and innate T cells into the brain. However, the role of these cells in the development of the brain injury is poorly understood. We review the mechanisms by which lymphocytes contribute to brain damage in NE. NK, T and innate T cells release proinflammatory cytokines contributing to the neurodegeneration in the secondary and tertiary phase of injury, whereas B cells and regulatory T cells produce IL-10 protecting the brain in NE. Targeting lymphocytes may have therapeutic potential in the treatment of NE in terms of management of inflammation and brain damage, particularly in the tertiary or persistent phases.

Serum cytokine profiling in neonates with hypoxic ischemic encephalopathy

BACKGROUND

The fetal brain is vulnerable to severe and sustained hypoxia during and after birth, which can lead to hypoxic-ischemic encephalopathy (HIE). HIE is characterized by clinical and laboratory evidence of acute or subacute brain injury. The role of cytokines in the pathogenesis of brain injury and their relation to neurological outcomes of asphyxiated neonates are not fully understood. In this study, we investigated cytokine profile related to cerebral palsy (CP) with neonatal hypoxic ischemic encephalopathy (HIE) and HIE severity.

METHODS

Eligible subjects were HIE newborns with a gestational age between 36 and 42 weeks. We included newborns who was born at our NICU and did not admit to NICU as healthy controls. The study comprised 52 newborns, including 13 with mild to severe HIE and 39 healthy control. Serum cytokine profiles were performed using a LUMINEX cytokine kit (R&D Systems).

RESULTS

VEGF, MCP-1, IL-15, IL-12p70, IL-12p40, IL-1Ra, IL-2, IL-6, IL-7, IL-8, IL-10, IFN-γ, G-CSF and eotaxin in the HIE patients were significantly increased compared with the healthy neonates. In the subgroup analysis, IL-6 and G-CSF were significantly increased in CP infants (n = 5) compared with non-CP infants (n = 8). Five and eight HIE patients were classified into the mild HIE and moderate-severe HIE groups, respectively. IL-6, 10, 1Ra, and G-CSF in the moderate-severe HIE group were significantly higher than those in the mild HIE group.

CONCLUSION

We demonstrated that higher serum IL-6 and G-CSF at birth in HIE patients were associated with CP and moderate-severe HIE.

Brain damage caused by neonatal hypoxia-ischemia and the effects of hypothermia in severe combined immunodeficient (SCID) mice

Neonatal hypoxic-ischemic encephalopathy (HIE) is a major cause of brain damage in newborns. Although therapeutic hypothermia has been shown to be neuroprotective against neonatal HIE in clinical trials, its effect is not satisfactory. Cell-based therapies have attracted much attention as novel treatments for HIE. Preclinical studies on a variety of human cell transplantation methods have been performed in immunodeficient/immunosuppressed animals, such as severe combined immunodeficient (SCID) mice, which lack functional T and B lymphocytes. The detailed characteristics of neonatal HIE in SCID mice, however, have not been delineated. In preclinical studies, novel therapies for neonatal HIE should be evaluated in combination with hypothermia, which has become a standard treatment for neonatal HIE. However, the effects of hypothermia in SCID mice have not been delineated. In the present study, we compared neonatal hypoxic-ischemic (HI) brain damage in SCID mice and wild-type mice treated with or without hypothermia. Male and female mouse pups were subjected to HI insult induced by unilateral common carotid artery ligation combined with systemic hypoxia on postnatal day 12. In the first 4 h after HI insult, body temperature was maintained at 36 °C for the normothermia groups or 32 °C for the hypothermia groups. The severity of brain damage in SCID mice did not differ from that in wild-type mice based on most evaluations, i.e., cerebral blood flow, hemiparesis, muscle strength, spontaneous activity, cerebral hemispheric volume, neuropathological injury, and serum cytokine levels, although spleen weight, brain weight, leukocyte counts and the levels of some cytokines in the peripheral blood were different between genotypes. The effects of hypothermia in SCID mice were comparable to those in wild-type mice based on most evaluations. Taken together, these findings indicate that SCID mice can be used as an appropriate preclinical model for cell therapies for neonatal HIE.