Background/Aims: Heat shock protein 70 (HSP70) has been recently described with extracellular actions, where it is actively released in inflammatory conditions. Acting as DAMPs (damage associated molecular pattern), extracellular HSP70 (eHSP70) interacts with membrane receptors and activates inflammatory pathways. At this context, the receptor for advanced glycation endproducts (RAGE) emerges as a possible candidate for interaction with eHSP70. RAGE is a pattern-recognition receptor and its expression is increased in several diseases related to a chronic pro-inflammatory state. One of the main consequences of RAGE ligand-binding is the ERK1/2 (extracellular signal–regulated kinases)-dependent activation of NF-kB (nuclear factor kappa B), which leads to expression of TNF-α (tumor necrosis factor alpha) and other cytokines. The purpose of this work is to elucidate if eHSP70 is able to evoke RAGE-dependent signaling using A549 human lung cancer cells, which constitutively express RAGE. Methods: Immunoprecipitation and protein proximity assay were utilized to demonstrate the linkage between RAGE and eHSP70. To investigate RAGE relevance on cell response to eHSP70, siRNA was used to knockdown the receptor expression. Signaling pathways activation were evaluated by western blotting, gene reporter luciferase and real time quantitative PCR. Results: Protein eHSP70 shown to be interacting physically with the receptor RAGE in our cell model. Treatment with eHSP70 caused ERK1/2 activation and NF-κB transactivation impaired by RAGE knockdown. Moreover, the stimulation of pro-inflammatory cytokines expression by eHSP70 was inhibited in RAGE-silenced cells. Finally, conditioned medium of eHSP70-treated A549 cells caused differential effects in monocytes cytokine expression when A549 RAGE expression is inhibited. Conclusions: Our results evidence eHSP70 as a novel RAGE agonist capable of influence the cross-talk between cancer and immune system cells.

Obesity is a health problem that has been associated with neuroinflammation, decreased cognitive functions and development of neurodegenerative diseases. Parkinson's disease (PD) is a chronic neurodegenerative condition characterized by motor and non-motor abnormalities, increased brain inflammation, α-synuclein protein aggregation and dopaminergic neuron loss that is associated with decreased levels of tyrosine hydroxylase (TH) in the brain. Diet-induced obesity is a global epidemic and its role as a risk factor for PD is not clear. Herein, we showed that 25 weeks on a high-fat diet (HFD) promotes significant alterations in the nigrostriatal axis of Wistar rats. Obesity induced by HFD exposure caused a reduction in TH levels and increased TH phosphorylation at serine 40 in the ventral tegmental area. These effects were associated with insulin resistance, increased tumor necrosis factor-α levels, oxidative stress, astrogliosis and microglia activation. No difference was detected in the levels of α-synuclein. Obesity also induced impairment of locomotor activity, total mobility and anxiety-related behaviors that were identified in the open-field and light/dark tasks. There were no changes in motor coordination or memory. Together, these data suggest that the reduction of TH levels in the nigrostriatal axis occurs through an α-synucleinindependent pathway and can be attributed to brain inflammation, oxidative/nitrosative stress and metabolic disorders induced by obesity.

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No abstract