Mariana Rodrigues Pereira

The Involvement of Parasympathetic and Sympathetic Nerve in the Inflammatory Reflex

Production of inflammatory cytokines plays important roles in the response against tissue injury and in host defense. Alterations in the production of inflammatory cytokines may cause local or systemic inflammatory imbalance, culminating in organ failure or lethal systemic inflammation. The cholinergic anti‐inflammatory pathway has been implicated as an important mechanism to regulate inflammation of targeted tissue. In this review, we discuss important advances, conflicting and controversial findings regarding the involvement of parasympathetic vagus and sympathetic splenic nerve through acetylcholine (ACh) release and α7 nicotinic acetylcholine receptor (nAChRα7) activation in the spleen. In addition, we address the involvement of cholinergic control of inflammation in other organs innerved by the vagus nerve such as gut, liver, kidney and lung, and independent of parasympathetic innervations such as skin and skeletal muscle. Then, other structures and mechanisms independent of vagus or splenic nerve may be involved in this process, such as local cells and motor neurons producing ACh. Altogether, the convergence of these findings may contribute to current anti‐inflammatory strategies involving selective drug‐targeting and electrical nerve stimulation. J. Cell. Physiol. 231: 1862–1869, 2016.

IL-6 treatment increases the survival of retinal ganglion cells in vitro: the role of adenosine A1 receptor.

IL-6 is a pleiotropic cytokine classically denominated pro-inflammatory. It has been already demonstrated that IL-6 can increase the survival of retinal ganglion cells (RGC) in culture. In this work, we show that the trophic effect of IL-6 is mediated by adenosine receptor (A1R) activation. The neutralization of extracellular BDNF abolished the IL-6 effect and the treatment with IL-6 and CHA (an agonist of A1R) modulated BDNF expression as well as pCREB and pTrkB levels.

Hazard effects of nanoparticles in central nervous system: Searching for biocompatible nanomaterials for drug delivery

Nanostructured materials are widely used in many applications of industry and biomedical fields. Nanoparticles emerges as potential pharmacological carriers that can be applied in the regenerative medicine, diagnosis and drug delivery. Different types of nanoparticles exhibit ability to cross the brain blood barrier (BBB) and accumulate in several brain areas. Then, efforts have been done to develop safer nanocarrier systems to treat disorders of central nervous system (CNS). However, several in vitro and in vivo studies demonstrated that nanoparticles of different materials exhibit a wide range of neurotoxic effects inducing neuroinflammation and cognitive impairment. For this reason, polymeric nanoparticles arise as a promisor alternative due to their biocompatible and biodegradable properties. After an overview of CNS location and neurotoxic effects of translocated nanoparticles, this review addresses the use of polymeric nanoparticles to the treatment of neuroinfectious diseases, as acquired immunodeficiency syndrome (AIDS) and meningitis.

Activation of glutamate receptors promotes a calcium-dependent and transporter-mediated release of purines in cultured avian retinal cells: possible involvement of calcium/calmodulin-dependent protein kinase II.

Calcium-dependent release of purines was previously demonstrated in cultures of chick retinal cells stimulated with high potassium concentrations but there is no evidence for an exocytotic mechanism of adenosine release from presynaptic terminals. Here we show that activation of NMDA or alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate (AMPA)/kainate glutamate ionotropic receptors promotes a two- to three-fold increase in the release of purines from these cultures. Approximately 96% of intracellular radioactivity is found as nucleotides after incubation with [(3)H]adenosine, but more than 85% of glutamate-stimulated released material is found as inosine (60%), hypoxanthine (19.9%) and adenosine (7.8%). The release is prevented by removal of extracellular calcium, by the transporter blocker nitrobenzylthioinosine, or inhibitors of calcium/calmodulin-dependent protein kinase II (CAMK II). The uptake of [(3)H]adenosine, but not of [(3)H]GABA or [(3)H]choline, is also blocked by 1-[N,O-bis(5-isoquinolinesulfonyl)-N-methyl-l-tyrosyl]-4-phenylpiperazine (KN62), N-[2-(N-(4-chlorocinnamyl)-N-methylaminomethyl)phenyl-N-[2-hydroxiethyl]-4-methoxybenzenesulfonamide (KN93) or the myristoylated autocamtide-2-related inhibitory peptide, suggesting that the enzyme modulates the nucleoside transporter. The distribution of intracellular purines was not affected by KN62. These results indicate that activation of glutamate receptors triggers the release of purines from retinal cells by a mechanism involving calcium influx, CAMK II and the nitrobenzylthioinosine-sensitive nucleoside transporter. The regulation of adenosine release by glutamate receptors and CAMK II could have important consequences in the presynaptic control of glutamate release.

Gold nanoparticles do not induce myotube cytotoxicity but increase the susceptibility to cell death

Gold nanoparticles (AuNP) have been widely used for many applications, including as biological carriers. A better understanding concerning AuNP safety on muscle cells is crucial, since it could be a potential tool in the nanomedicine field. Here, we describe the impact of polyethylene glycol-coated gold nanoparticles (PEG-AuNP) interaction with differentiated skeletal muscle C2C12 cells on cell viability, mitochondria function, cell signaling related to survival, cytokine levels and susceptibility to apoptosis. Intracellular localization of 4.5 nm PEG-AuNP diameter size was evidenced by STEM-in-SEM in myotube cells. Methods for cytotoxicity analysis showed that PEG-AuNP did not affect cell viability, but intracellular ATP levels and mitochondrial membrane potential increased. Phosphorylation of ERK was not altered but p-AKT levels reduced (p<0.01). Pre-treatment of cells with PEG-AuNP followed by staurosporine induction increased the caspases-3/7 activity. Indeed, cytokines analysis revealed a sharp increase of IFN-γ and TGF-β1 levels after PEG-AuNP treatment, suggesting that inflammatory and fibrotic phenotypes process were activated. These data demonstrate that PEG-AuNP affect the myotube physiology leading these cells to be more susceptible to death stimuli in the presence of staurosporine. Altogether, these results present evidence that PEG-AuNP affect the susceptibility to apoptosis of muscle cells, contributing to development of safer strategies for intramuscular delivery.

Expression of A1 adenosine receptors in the developing avian retina: in vivo modulation by A2A receptors and endogenous adenosine

Little is known about the mechanisms that regulate the expression of adenosine receptors during CNS development. We demonstrate here that retinas from chick embryos injected in ovo with selective adenosine receptor ligands show changes in A1 receptor expression after 48 h. Exposure to A1 agonist N6‐cyclohexyladenosine (CHA) or antagonist 8‐Cyclopentyl‐1, 3‐dipropylxanthine (DPCPX) reduced or increased, respectively, A1 receptor protein and [3H]DPCPX binding, but together, CHA+DPCPX had no effect. Interestingly, treatment with A2A agonist 3‐[4‐[2‐[[6‐amino‐9‐[(2R,3R,4S,5S)‐5‐(ethylcarbamoyl)‐3,4‐dihydroxy‐oxolan‐2‐yl]purin‐2‐yl]amino] ethyl]phenyl] propanoic acid (CGS21680) increased A1 receptor protein and [3H]DPCPX binding, and reduced A2A receptors. The A2A antagonists 7‐(2‐phenylethyl)‐5‐amino‐2‐(2‐furyl)‐pyrazolo‐[4,3‐e]‐1,2,4‐trizolo[1,5‐c] pyrimidine (SCH58261) and 4‐(2‐[7‐amino‐2‐[2‐furyl][1,2,4]triazolo[2,3‐a][1,3,5]triazo‐5‐yl‐amino]ethyl)phenol (ZM241385) had opposite effects on A1 receptor expression. Exposure to CGS21680 + CHA did not change A1 receptor levels, whereas CHA + ZM241385 or CGS21680 + DPCPX had no synergic effect. The blockade of adenosine transporter with S‐(4‐nitrobenzyl)‐6‐thioinosine (NBMPR) also reduced [3H]DPCPX binding, an effect blocked by DPCPX, but not enhanced by ZM241385. [3H]DPCPX binding kinetics showed that treatment with CHA reduced and CGS21680 increased the Bmax, but did not affect Kd values. CHA, DPCPX, CGS21680, and ZM241385 had no effect on A1 receptor mRNA. These data demonstrated an in vivo regulation of A1 receptor expression by endogenous adenosine or long‐term treatment with A1 and A2A receptors modulators.

Modulation of A1 adenosine receptor expression by cell aggregation and long-term activation of A2a receptors in cultures of avian retinal cells: involvement of the cyclic AMP/PKA pathway.

J. Neurochem. (2010) 113, 661–673.

Adenosine Transporters and Receptors: Key Elements for Retinal Function and Neuroprotection

Adenosine is an important neuroactive substance in the central nervous system, including in the retina where subclasses of adenosine receptors and transporters are expressed since early stages of development. Here, we review some evidence showing that adenosine plays important functions in the mature as well as in the developing tissue. Adenosine transporters are divided into equilibrative and concentrative, and the major transporter subtype present in the retina is the ENT1. This transporter is responsible for a bidirectional transport of adenosine and the uptake or release of this nucleoside appears to be regulated by different signaling pathways that are also controlled by activation of adenosine receptors. Adenosine receptors are also key players in retina physiology regulating a variety of functions in the mature and developing tissue. Regulation of excitatory neurotransmitter release and neuroprotection are the main functions played be adenosine in the mature tissue, while regulation of cell survival and neurogenesis are some of the functions played by adenosine in developing retina. Since adenosine is neuroprotective against excitotoxic and metabolic dysfunctions observed in neurological and ocular diseases, the search for adenosine-related drugs regulating adenosine transporters and receptors can be important for advancement of therapeutic strategies against these diseases.

Adenosine Transporters and Receptors

Adenosine is an important neuroactive substance in the central nervous system, including in the retina where subclasses of adenosine receptors and transporters are expressed since early stages of development. Here, we review some evidence showing that adenosine plays important functions in the mature as well as in the developing tissue. Adenosine transporters are divided into equilibrative and concentrative, and the major transporter subtype present in the retina is the ENT1. This transporter is responsible for a bidirectional transport of adenosine and the uptake or release of this nucleoside appears to be regulated by different signaling pathways that are also controlled by activation of adenosine receptors. Adenosine receptors are also key players in retina physiology regulating a variety of functions in the mature and developing tissue. Regulation of excitatory neurotransmitter release and neuroprotection are the main functions played be adenosine in the mature tissue, while regulation of cell survival and neurogenesis are some of the functions played by adenosine in developing retina. Since adenosine is neuroprotective against excitotoxic and metabolic dysfunctions observed in neurological and ocular diseases, the search for adenosine-related drugs regulating adenosine transporters and receptors can be important for advancement of therapeutic strategies against these diseases.