In vivo indomethacin treatment causes microglial activation in adult mice

Neurodegeneration: Microglia: Nf-Kappab Signaling Pathways

Microglia is cells of mesodermal/mesenchymal origin that migrate into the central nervous system (CNS) to form resident macrophages inside the special brain microenvironment. Intact with both neuronal and non-neuronal cells, microglia is highly active cells. Continuous process extension and retraction allows microglia to scan the brain parenchyma for threats. They are also able to change their morphology from ramified to amoeboid, which is a sign of cell activity. In response to pleiotropic stimuli such as neurotransmitters, cytokines, and plasma proteins, microglia express a diverse range of receptors. As controllers of synaptic activities and phagocytosis of developing neurons, they serve a critical role in the healthy brain and have significant effects on synaptic plasticity and adult neurogenesis. A frequent cause of hypoparathyroidism is a mutation in the gene glial cells missing-2 (GCM2). Neonatal hypoparathyroidism has an amorphic recessive GCM2 mutation, while autosomal dominant hypoparathyroidism has a dominant-negative GCM2 mutation. Curiously, familial isolated hyperparathyroidism has been associated with activating GCM2 mutation. In addition to seizures, neurocognitive impairment, carpopedal spasm, tingling and numbness are common clinical manifestations of hypoparathyroidism. Biogenic amines are a group of four neurotransmitters that belong to that category and these include serotonin, dopamine, norepinephrine, and epinephrine. Numerous antidepressants prevent the reuptake from occurring the brain-gut axis is hardwired through the CNS, enteric nervous system (ENS), neuroendocrine linkages and highly innervated nerve plexuses.

Indomethacin augments lipopolysaccharide-induced expression of inflammatory molecules in the mouse brain

Indomethacin and other non-steroidal anti-inflammatory drugs (NSAIDs) are used to relieve pain and fever including during infections. However, some studies suggest that NSAIDs protect against neuroinflammation, while some find no effects or worsening of neuroinflammation. We evaluated the effect of indomethacin alone on in combination with minocycline, a drug that inhibits neuroinflammation, on the expression of transcripts of neuroinflammatory molecules-induced by lipopolysaccharide (LPS) in the brain of mice. Inoculation of male BALB/c mice with LPS induced the expression of the microglia marker ionized calcium binding adaptor molecule protein, mRNA expression of the genes for cytokines interleukin-1beta (Il1b) and tumor necrosis factor-alpha (Tnf) and inducible nitric oxide synthase gene (Nos2), but not Il10, in the brain. Treatment with indomethacin had no significant effect on the cytokines or Nos2 mRNA expression in naïve animals. However, pretreatment with indomethacin increased LPS-induced Nos2 mRNA and inducible nitric oxide (iNOS) protein expression, but had no significant effect on LPS-induced mRNA expression of the cytokines. Minocycline reduced LPS-induced Il1b and Tnf, but not Nos2, mRNA expression. Treatment with indomethacin plus minocycline had no effect on LPS-induced Il1b, Tnf and Nos2 mRNA expression. In conclusion these results show that indomethacin significantly augments LPS-induced Nos2 mRNA and iNOS protein expression in the brain. In the presence of indomethacin, minocycline could not inhibit LPS-induced pro-inflammatory cytokine expression. Thus, indomethacin could exacerbate neuroinflammation by increasing the expression of iNOS and also block the anti-inflammatory effects of minocycline.

Consistent inhibition of cyclooxygenase drives macrophages towards the inflammatory phenotype

Macrophages play important roles in defense against infection, as well as in homeostasis maintenance. Thus alterations of macrophage function can have unexpected pathological results. Cyclooxygenase (COX) inhibitors are widely used to relieve pain, but the effects of long-term usage on macrophage function remain to be elucidated. Using bone marrow-derived macrophage culture and long-term COX inhibitor treatments in BALB/c mice and zebrafish, we showed that chronic COX inhibition drives macrophages into an inflammatory state. Macrophages differentiated in the presence of SC-560 (COX-1 inhibitor), NS-398 (COX-2 inhibitor) or indomethacin (COX-1/2 inhibitor) for 7 days produced more TNFα or IL-12p70 with enhanced p65/IκB phosphoylation. YmI and IRF4 expression was reduced significantly, indicative of a more inflammatory phenotype. We further observed that indomethacin or NS-398 delivery accelerated zebrafish death rates during LPS induced sepsis. When COX inhibitors were released over 30 days from an osmotic pump implant in mice, macrophages from peritoneal cavities and adipose tissue produced more TNFα in both the basal state and under LPS stimulation. Consequently, indomethacin-exposed mice showed accelerated systemic inflammation after LPS injection. Our findings suggest that macrophages exhibit a more inflammatory phenotype when COX activities are chronically inhibited.

Indomethacin protects against neurodegeneration caused by MPTP intoxication in mice

The anti-inflammatory agents are postulated to be effective in treating neurodegenerative disorders. In this study, we showed that indomethacin (IND) in the dose of 1 mg/kg protected neurons against toxic damage caused by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in mice model of Parkinson's disease. IND also diminished microglial activation and lymphocytic infiltration in the injured areas. These observations suggest that anti-inflammatory properties of IND may play a role in the neuron's protection in this model. However, diminished inflammatory reaction may be secondary to less neuronal damage.

Microglial activation and beta -amyloid deposit reduction caused by a nitric oxide-releasing nonsteroidal anti-inflammatory drug in amyloid precursor protein plus presenilin-1 transgenic mice

3-4-(2-Fluoro-alpha-methyl-[1,1'-biphenyl]-4-acetyloxy)-3-methoxyphenyl]-2-propenoic acid 4-nitrooxy butyl ester (NCX-2216), a nitric oxide (NO)-releasing derivative of the cyclooxygenase-1-preferring nonsteroidal anti-inflammatory drug (NSAID) flurbiprofen, dramatically reduced both beta-amyloid (Abeta) loads and Congo red staining in doubly transgenic (Tg) amyloid precursor protein plus presenilin-1 mice when administered at 375 ppm in diet between 7 and 12 months of age. This reduction was associated with a dramatic increase in the number of microglia expressing major histocompatibility complex-II antigen, a marker for microglial activation. In contrast, ibuprofen at 375 ppm in diet caused modest reductions in Abeta load but not Congo red staining, suggesting that the effects of this nonselective NSAID were restricted primarily to nonfibrillar deposits. We detected no effects of the cyclooxygenase-2-selective NSAID celecoxib at 175 ppm on amyloid deposition. In short-term studies of 12-month-old Tg mice, we found that the microglia-activating properties of NCX-2216 (7.5 mg small middle dot kg(-1) small middle dot d(-1), s.c.) were present after 2 weeks of treatment. Microglia were not activated by NCX-2216 in non-Tg mice lacking Abeta deposits, nor were microglia activated in Tg animals by flurbiprofen (5 mg small middle dot kg(-1) small middle dot d(-1)) alone. These data are consistent with the argument that activated microglia can clear Abeta deposits. We conclude that the NO-generating component of NCX-2216 confers biological actions that go beyond those of typical NSAIDs. In conclusion, NCX-2216 is more efficacious than ibuprofen or celecoxib in clearing Abeta deposits from the brains of Tg mice, implying potential benefit in the treatment of Alzheimer's dementia.