Neuroprotective role of minocycline in co-cultures of human fetal neurons and microglia

University of Connecticut Health Center, Department of Neuroscience, 263 Farmington Avenue, Farmington, CT 06030-3401, USA.
Experimental Neurology (Impact Factor: 4.7). 06/2008; 211(1):41-51. DOI: 10.1016/j.expneurol.2007.12.024
Source: PubMed


Bacterial infections during pregnancy often result in premature birth and neonatal white matter damage. During these infections, microglia, the resident immune cells of the CNS, undergo activation and contribute to further neuronal damage of the CNS. Minocycline, a second-generation tetracycline antibiotic, inhibits microglial activation and protects neurons in rodents but data about its effects on human cells are limited. We studied the mechanism of the neuroprotective effect of minocycline in either purified cell cultures or co-cultures of microglia and neurons from human fetal brain during inflammation induced by lipopolysaccharide (LPS). In neuron/microglial co-cultures, minocycline treatment prevented activation and proliferation of microglia and protected neurons as demonstrated by decreased neuronal cell death and a shift of Bcl-2 family proteins toward anti-apoptotic ratio. Notably, neither minocycline nor LPS had an effect on neurons in purified neuronal cultures. The ability of minocycline to regulate activation of human fetal microglia might be relevant in therapies used towards treating neonatal CNS infections.

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    • "We demonstrated in our previous study that chronic administration of minocycline attenuated the development of neuropathic pain and enhanced morphine analgesia [45], [46], [47]. Filipovic and Zecevic [48] demonstrated in in vitro studies that minocycline protects neurons from LPS-induced inflammation by inhibiting the activation of microglia. Activated microglia may weaken morphine analgesia by releasing pronociceptive factors, and the administration of minocycline antagonises this weakening [23], [46], [47]. "
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    ABSTRACT: The analgesic effect of delta-opioid receptor (DOR) ligands in neuropathic pain is not diminished in contrast to other opioid receptor ligands, which lose their effectiveness as analgesics. In this study, we examine whether this effect is related to nerve injury-induced microglial activation. We therefore investigated the influence of minocycline-induced inhibition of microglial activation on the analgesic effects of opioid receptor agonists: morphine, DAMGO, U50,488H, DPDPE, Deltorphin II and SNC80 after chronic constriction injury (CCI) to the sciatic nerve in rats. Pre-emptive and repeated administration of minocycline (30 mg/kg, i.p.) over 7 days significantly reduced allodynia and hyperalgesia as measured on day 7 after CCI. The antiallodynic and antihyperalgesic effects of intrathecally (i.t.) administered morphine (10-20 µg), DAMGO (1-2 µg) and U50,488H (25-50 µg) were significantly potentiated in rats after minocycline, but no such changes were observed after DPDPE (10-20 µg), deltorphin II (1.5-15 µg) and SNC80 (10-20 µg) administration. Additionally, nerve injury-induced down-regulation of all types of opioid receptors in the spinal cord and dorsal root ganglia was not influenced by minocycline, which indicates that the effects of opioid ligands are dependent on other changes, presumably neuroimmune interactions. Our study of rat primary microglial cell culture using qRT-PCR, Western blotting and immunocytochemistry confirmed the presence of mu-opioid receptors (MOR) and kappa-opioid receptors (KOR), further we provide the first evidence for the lack of DOR on microglial cells. In summary, DOR analgesia is different from analgesia induced by MOR and KOR receptors because it does not dependent on injury-induced microglial activation. DOR agonists appear to be the best candidates for new drugs to treat neuropathic pain.
    PLoS ONE 08/2014; 9(8):e104420. DOI:10.1371/journal.pone.0104420 · 3.23 Impact Factor
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    • "However, the use of tetracyclines, including minocycline, during tooth development has been shown to cause permanent tooth discoloration and enamel hypoplasia, and a decrease in bone growth. Furthermore, emergence of resistant bacteria strains in neonatal intensive care units (NICU’s) is a major issue limiting the use of antibiotics in non-infectious scenarios (15, 16). "
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    ABSTRACT: Perinatal brain damage is one of the leading causes of life long disability. This damage could be hypoxic-ischemic, inflammatory, or both. This mini-review discusses different interventions aiming at minimizing inflammatory processes in the neonatal brain, both before and after insult. Current options of anti-inflammatory measures for neonates remain quite limited. We describe current anti-inflammatory intervention strategies such as avoiding perinatal infection and inflammation, and reducing exposure to inflammatory processes. We describe the known effects of anti-inflammatory drugs such as steroids, antibiotics, and indomethacin, and the possible anti-inflammatory role of other substances such as IL-1 receptor antagonists, erythropoietin, caffeine, estradiol, insulin-like growth factor, and melatonin as well as endogenous protectors, and genetic regulation of inflammation. If successful, these may decrease mortality and long-term morbidity among term and pre-term infants.
    Frontiers in Pediatrics 04/2014; 2:30. DOI:10.3389/fped.2014.00030
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    • "Microglial cells are the resident macrophages of the central nervous system, and can produce and release a vast array of inflammatory mediators including pro-inflammatory cytokines when activated. Several studies indicate that microglial activation is detrimental to the immature brain (Fan et al., 2005; Filipovic and Zecevic, 2008; Lechpammer et al., 2008), although there are contrasting data suggesting that inhibition of microglial activation does not improve outcome (Arvin et al., 2002; Tsuji et al., 2004), while in adult models microglia can even be neuroprotective (Lalancette-Hebert et al., 2007; Simard and Rivest, 2007). Microglia sense changes in their environment via pattern recognition receptors located within the plasma membrane, including those belonging to the Toll-like receptor (TLR) family (Aravalli et al., 2007; Olson and Miller, 2004). "
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    ABSTRACT: Although the role of microglial activation in neural injury remains controversial, there is increasing evidence for a detrimental effect in the immature brain, which may occur in response to release of neurotoxic substances including pro-inflammatory cytokines. However, the signaling mechanisms involved in microglial-induced neuronal cell death are unclear. Microglia isolated from the brains of wild-type (WT) or MyD88 knockout (KO) mice were exposed to PBS or the TLR4-ligand LPS (100 ng/mL) for 2, 6, 14, or 24 h, and the microglia-conditioned medium (MCM) collected. Detection of multiple inflammatory molecules in MCM was performed using a mouse 22-plex cytokine microbead array kit. Primary neuronal cultures were supplemented with the 14 or 24 h MCM, and the degree of neuronal apoptosis examined after exposure for 24 h. Results showed a rapid and sustained elevation in multiple inflammatory mediators in the MCM of WT microglia exposed to LPS, which was largely inhibited in MyD88 KO microglia. There was a significant increase in apoptotic death measured at 24 h in cultured neurons exposed to CM from either 14 or 24 h LPS-stimulated WT microglia (p<.05 vs. WT control). By contrast, there was no increase in apoptotic death in cultured neurons exposed to CM from 14 or 24 h LPS-stimulated MyD88 KO microglia (p=.15 vs. MyD88 KO control). These data suggest that MyD88-dependent activation of microglia by LPS causes release of factors directly toxic to neurons.
    Brain Behavior and Immunity 11/2009; 24(5):776-83. DOI:10.1016/j.bbi.2009.10.018 · 5.89 Impact Factor
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