Osteopontin regulates proliferation, migration, and survival of astrocytes depending on their activation phenotype

Abstract

The glycoprotein osteopontin is highly upregulated in central nervous system (CNS) disorders such as ischemic stroke. Osteopontin regulates cell growth, cell adhesion, homeostasis, migration, and survival of various cell types. Accordingly, osteopontin is considered an essential regulator of regeneration and repair in the ischemic milieu. Astrocytes are the most abundant cells in the CNS and play significant roles in health and disease. Astrocytes are involved in homeostasis, promote neuroprotection, and regulate synaptic plasticity. Upon activation, astrocytes may adopt different phenotypes, termed A1 and A2. The direct effects of osteopontin on astrocytes, especially in distinct activation states, are yet unknown. The current study aimed to elucidate the impact of osteopontin on resting and active astrocytes. We established an inflammatory in vitro model of activated (A1) primary astrocytes derived from neonatal wistar rats by exposure to a distinct combination of proinflammatory cytokines. To model ischemic stroke in vitro, astrocytes were subjected to oxygen and glucose deprivation (OGD) in the presence or absence of osteopontin. Osteopontin modulated the activation phenotype by attenuating A1‐ and restoring A2‐marker expression without compromising the active astrocytes’ immunocompetence. Osteopontin promoted the proliferation of active and the migration of resting astrocytes. Following transient OGD, osteopontin mitigated the delayed ongoing death of primary astrocytes, promoting their survival. Data suggest that osteopontin differentially regulates essential functions of resting and active astrocytes and confirm a significant regulatory role of osteopontin in an in vitro ischemia model. Furthermore, the data suggest that osteopontin constitutes a promising target for experimental therapies modulating neuroregeneration and repair.

Glia from the central and peripheral nervous system are differentially affected by paclitaxel chemotherapy via modulating their neuroinflammatory and neuroregenerative properties

“…After 24 h exposure to 1 μM, 5 μM, 10 μM, and 50 μM paclitaxel apoptotic microglia, astrocytes and SGCs, as well as neuronal stem cells after exposure to glial supernatant, were stained with propidium iodide (Life Technologies, Darmstadt, Germany) and all cells were counterstained with Hoechst 33342 (Life Technologies, Darmstadt, Germany) following the protocol as previously described ( Vay et al, 2021 ). Images were taken with the BZ-9000 microscope (Keyence, Japan).…”

“…Bromodeoxyuridine (BrdU; Cayman Chemical Company, United States) is a thymidine analogue and serves to label and quantify proliferating cells. Eighteen hours after treatment of microglia, astrocytes and SGCs with 1 μM or 5 μM paclitaxel, 10 µM BrdU was offered to each well as previously described ( Vay et al, 2021 ). After 6 h of incubation, the experiment was stopped by cell fixation with 4% PFA, and cells were stained for incorporated BrdU (see below).…”

“…Pure neonatal astrocytes and microglia cultures were obtained from the cortices of 20 male and female neonatal Wistar rats (P1-P3) according to the protocol of Vay et al, 2021. Rat cortices were incubated in trypsin/EDTA solution (0.05% trypsin, 0.02% EDTA) for 15 min at 37 °C. The addition of the culture medium (DMEM with 10% FBS, 1% penicillin/streptomycin, and 2 mM L-glutamine) stopped the reaction.…”

Markers of neutrophil mediated inflammation associate with disturbed continuous electroencephalogram after out of hospital cardiac arrest

“…Alongside a detrimental effect in the early phase of IRI, OPN would exert a neuroprotective role mainly relying on its roles in the balancing of anti−/pro‐inflammatory responses, blood–brain barrier integrity as well as proliferation of active and the migration of resting astrocytes. 32 In line with that, OPN is under investigation as potential candidate for therapeutic application in acute brain injury. 31 Similarly, the amplification of oxidative burst sustained by neutrophil recruitment and activation may ultimately sustain neuronal recovery by both genetic and epigenetic mechanisms.…”

“…Neutrophil recruitment and oxidative burst–of which OPN and MPO may be considered as surrogate markers, respectively–indeed represent a double edge sword. Alongside a detrimental effect in the early phase of IRI, OPN would exert a neuroprotective role mainly relying on its roles in the balancing of anti−/pro‐inflammatory responses, blood–brain barrier integrity as well as proliferation of active and the migration of resting astrocytes 32 . In line with that, OPN is under investigation as potential candidate for therapeutic application in acute brain injury 31 .…”