Epiisopiloturine, an Alkaloid from Pilocarpus microphyllus, Attenuates LPS-Induced Neuroinflammation by Interfering in the TLR4/NF-κB-MAPK Signaling Pathway in Microglial Cells.

Neuroinflammation is present in the pathophysiological mechanisms of several diseases that affect the central nervous system (CNS). Microglia have a prominent role in initiating and sustaining the inflammatory process. Epiisopiloturine (EPI) is an imidazole alkaloid obtained as a by-product of pilocarpine extracted from Pilocarpus microphyllus (jaborandi) and has shown promising anti-inflammatory and antinociceptive properties. In the present study, we investigated the effects of EPI on the inflammatory response in microglial cells (BV-2 cells) induced by lipopolysaccharide (LPS) and explored putative underlying molecular mechanisms. Cell viability was not affected by EPI (1-100 µg/mL) as assessed by both LDH activity and the MTT test. Pretreatment with EPI (25, 50, and 100 µg/mL) significantly reduced the proinflammatory response induced by LPS, as observed by a decrease in nitrite oxide production and iNOS protein expression. EPI (25 µg/mL) reduced IL-6 and TNF-α production, by 40% and 34%, respectively. However, no changes were observed in the anti-inflammatory IL-10 production. Mechanistically, EPI inhibited the TLR4 expression and phosphorylation of NF-κB p65 and MAPKs (JNK and ERK1/2) induced by LPS, but no changes were observed in TREM2 receptor expression in LPS-stimulated cells. In conclusion, our data demonstrated the potent anti-inflammatory properties of EPI in microglial cells. These effects are associated with the reduction of TLR4 expression and inhibition of intracellular signaling cascades, including NF-κB and MAPKs (JNK and ERK1/2).

Chemerin Regulates Crosstalk Between Adipocytes and Vascular Cells Through Nox.

Adipocytes produce adipokines, including chemerin, a chemoattractant that mediates effects through its ChemR23 receptor. Chemerin has been linked to endothelial dysfunction and vascular injury in pathological conditions, such as obesity, diabetes mellitus, and hypertension. Molecular mechanisms underlying this are elusive. Here we assessed whether chemerin through redox-sensitive signaling influences molecular processes associated with vascular growth, apoptosis, and inflammation. Human microvascular endothelial cells and vascular smooth muscle cells were stimulated with chemerin (50 ng/mL). Chemerin increased generation of reactive oxygen species and phosphorylation of mitogen-activated protein kinases, effects that were inhibited by ML171, GKT137831 (Nox inhibitors), and N-acetylcysteine (reactive oxygen species scavenger). Chemerin increased mRNA expression of proinflammatory mediators in vascular cells and increased monocyte-to-endothelial cell attachment. In human vascular smooth muscle cells, chemerin induced phosphorylation of mitogen-activated protein kinases and stimulated proliferation (increased proliferating cell nuclear antigen expression [proliferation marker] and BrdU incorporation [proliferation assay]). Chemerin decreased phosphatidylinositol 3-kinase/protein kinase B activation and increased TUNEL-positive human vascular smooth muscle cells. In human microvascular endothelial cells, chemerin reduced endothelial nitric oxide synthase activity and nitric oxide production. Adipocyte-conditioned medium from obese/diabetic mice (db/db), which have elevated chemerin levels, increased reactive oxygen species generation in vascular smooth muscle cells, whereas adipocyte-conditioned medium from control mice had no effect. Chemerin actions were blocked by CCX 832, a ChemR23 inhibitor. Our data demonstrate that chemerin, through Nox activation and redox-sensitive mitogen-activated protein kinases signaling, exerts proapoptotic, proinflammatory, and proliferative effects in human vascular cells. These findings elucidate some molecular mechanisms through chemerin, which is increased in obesity, whereby adipocytes may influence vascular function. We identify chemerin as a novel vasoactive adipokine, which may be important in obesity-related vascular injury.

Oxidative stress and modification of renal vascular permeability are associated with acute kidney injury during P. berghei ANKA infection.

Malaria associated-acute kidney injury (AKI) is associated with 45% of mortality in adult patients hospitalized with severe form of the disease. However, the causes that lead to a framework of malaria-associated AKI are still poorly characterized. Some clinical studies speculate that oxidative stress products, a characteristic of Plasmodium infection, as well as proinflammatory response induced by the parasite are involved in its pathophysiology. Therefore, we aimed to investigate the development of malaria-associated AKI during infection by P. berghei ANKA, with special attention to the role played by the inflammatory response and the involvement of oxidative stress. For that, we took advantage of an experimental model of severe malaria that showed significant changes in the renal pathophysiology to investigate the role of malaria infection in the renal microvascular permeability and tissue injury. Therefore, BALB/c mice were infected with P. berghei ANKA. To assess renal function, creatinine, blood urea nitrogen, and ratio of proteinuria and creatininuria were evaluated. The products of oxidative stress, as well as cytokine profile were quantified in plasma and renal tissue. The change of renal microvascular permeability, tissue hypoxia and cellular apoptosis were also evaluated. Parasite infection resulted in renal dysfunction. Furthermore, we observed increased expression of adhesion molecule, proinflammatory cytokines and products of oxidative stress, associated with a decrease mRNA expression of HO-1 in kidney tissue of infected mice. The measurement of lipoprotein oxidizability also showed a significant increase in plasma of infected animals. Together, our findings support the idea that products of oxidative stress, as well as the immune response against the parasite are crucial to changes in kidney architecture and microvascular endothelial permeability of BALB/c mice infected with P. berghei ANKA.

Differential expression of cytokines, chemokines and chemokine receptors in patients with coronary artery disease.

Monocytes/macrophages and lymphocytes have a key role in the pathogenesis of atherosclerosis through the production of inflammatory and anti-inflammatory cytokines. We evaluated mRNA expression and protein production of CCL2, CXCL8, CXCL9, CXCL10, IFN-gamma and IL-10 in vitro as well as the expression of the CCR2 and CXCR3 receptors in peripheral blood mononuclear cells (PBMCs) of patients with coronary artery disease (CAD) and healthy controls in the presence or absence of oxidized LDL (oxLDL). Patients with CAD showed higher constitutive expression of CCL2, CXCL8, CXCL9, CXCL10 and IFN-gamma mRNA and, after stimulation with oxLDL, higher expression of CCL2 and CXCL8 mRNA than the control group. We also detected higher levels of CCL2 and CXCL8 in supernatants of oxLDL-stimulated PBMCs from CAD patients than in corresponding supernatants from controls. Patients with CAD had a higher percentage of constitutive CCR2(+) and CXCR3(+) cells after stimulation with oxLDL. Among CAD patients, the main differences between the stable (SA) and unstable angina (UA) groups were lower IL-10 mRNA production in the latter group. Altogether, our data suggest that PBMCs from CAD patients are able to produce higher concentrations of chemokines and cytokines involved in the regulation of monocyte and lymphocyte migration and retention in atherosclerotic lesions.