دانلود رایگان مقاله آستروسیتهای التهابی واکنشی به عنوان اهداف التهاب

Abstract

This study aimed to test pharmaceutical compounds targeting astrocytes showing inflammatory dysregulation. The primary rat brain cultures were treated with different batches of serum with or without microglia added to make the cells inflammatory-reactive. Lipopolysaccharide (LPS) and tryptase were used as inflammatory inducers. Expression levels of Toll-like receptor 4 (TLR4), Na+/K+-ATPase, and matrix metalloprotease-13 (MMP-13), as well as actin filament organization, pro-inflammatory cytokines, and intracellular Ca2+ release, were evaluated. LPS combined with tryptase upregulated TLR4 expression, whereas Na+/K+-ATPase expression was downregulated, ATP-evoked Ca2+ transients were increased, actin filaments were reorganized and ring structures instead of stress fibers were observed. Other aims of the study were to prevent astrocytes from becoming inflammatory-reactive and to restore inflammatory dysregulated cellular changes. A combination of the μ-opioid antagonist (−)-naloxone in ultra-low concentrations, the non-addictive μ-opioid agonist (−)-linalool, and the anti-epileptic agent levetiracetam was examined. The results indicated that this drug cocktail prevented the LPS- and tryptase-induced inflammatory dysregulation. The drug cocktail could also restore the LPS- and tryptase-treated cells back to a normal physiological level in terms of the analyzed parameters.

4. Discussion

Inflammation in the CNS differs from inflammation elsewhere in the body because of the sensitivity and isolation of the CNS. Microglia produce anti-inflammatory and neurotrophic factors under physiological conditions and produce pro-inflammatory mediators in response to infection or tissue damage (Streit, 2002). They act on astrocytes that in turn amplify the inflammatory reaction (Saijo et al., 2009). Therefore, microglia and astrocytes are of particular interest because both cell types can initiate and amplify inflammation and thereby release neurotoxic compounds. Therefore, an in vitro cell model system of inflammation is desirable for studying potential treatments, which is even better than the one used by us in earlier experiments (Block et al., 2013). The astrocyte cultures were investigated using different cultivation parameters. Two different fetal calf sera were used to promote microglial growth. Furthermore, the cultures were shaken to recruit more microglia. Microglia from external cultures were also added. We hypothesized that the number of microglia and/or the reactivity of these cells could make the astrocytes inflammatoryreactive (DeLeo et al., 2004; Milligan and Watkins, 2009). Our results show that astrocytes and microglia are not capable of initiating inflammation by themselves, but microglia do appear to be at least partly responsible for the changes induced in known biomarkers, with a stronger induction of TLR4 and reduced expression of Naþ/Kþ-ATPase, but without the release of pro-inflammatory cytokines.