Involvement of nitric oxide in the mitochondrial action of efavirenz: a differential effect on neurons and glial cells

The anti-human immunodeficiency virus (HIV) drug efavirenz (EFV) alters mitochondrial function in cultured neurons and glial cells. Nitric oxide (NO) is a mediator of mitochondrial dysfunction associated with HIV central nervous system symptoms. We show that EFV promotes inducible nitric oxide synthase (iNOS) expression in cultured glial cells and generated NO undermines their mitochondrial function, as inhibition of NOS partially reverses this effect. EFV inhibits mitochondrial Complex I in both neurons and glia; however, when the latter cells are treated for longer periods, other mitochondrial complexes are also affected in accordance with the increased NO production. These findings shed light on the mechanisms responsible for the frequent EFV-associated neurotoxicity

Neuronal Bioenergetics and Acute Mitochondrial Dysfunction: A Clue to Understanding the Central Nervous System Side Effects of Efavirenz

Background. Neurological pathogenesis is associated with mitochondrial dysfunction and differences in neuronal/glial handling of oxygen and glucose. The main side effects attributed to efavirenz involve the CNS, but the underlying mechanisms are unclear. Methods. Human cell lines and rat primary cultures of neurons and astrocytes were treated with clinically relevant efavirenz concentration. Results. Efavirenz alters mitochondrial respiration, enhances reactive oxygen species generation, undermines mitochondrial membrane potential, and reduces adenosine triphosphate (ATP) levels in a concentration-dependent fashion in both neurons and glial cells. However, it activates adenosine monophosphate–activated protein kinase only in glial cells, upregulating glycolysis and increasing intracellular ATP levels, which do not occur in neurons. To reproduce the conditions that often exist in human immunodeficiency virus–related neuroinflammatory disorders, the effects of efavirenz were evaluated in the presence of exogenous nitric oxide, an inflammatory mediator and mitochondrial inhibitor. The combination potentiated the effects on mitochondrial parameters in both neurons and glial cells, but ATP generation and lactate production were enhanced only in glial cells. Conclusions. Efavirenz affects the bioenergetics of neurons through a mechanism involving acute mitochondrial inhibition, an action exacerbated in neuroinflammatory conditions. A similar scenario of glial cells survival and degeneration of neurons with signs of mitochondrial dysfunction and oxidative stress has been associated with neurocognitive disorders

Abacavir increases purinergic P2X7 receptor activation by ATP: does a pro-inflammatory synergism underlie its cardiovascular toxicity?

16 p.-9 fig.-1 tab.The cardiovascular toxicity of Abacavir is related to its purinergic structure. Purinergic P2X7-receptors (P2X7R), characterized by activation by high concentrations of ATP and with high plasticity, seem implicated. We appraise the nature of the interplay between Abacavir and P2X7R in generating vascular inflammation. The effects of Abacavir on leukocyte-endothelium interactions were compared with those of its metabolite carbovir triphosphate (CBV-TP) or ATP in the presence of apyrase (ATP-ase) or A804598 (P2X7R-antagonist). CBV-TP and ATP levels were evaluated by HPLC, while binding of Abacavir, CBV-TP and ATP to P2X7R was assessed by radioligand and docking studies. Hypersensitivity studies explored a potential allosteric action of Abacavir. Clinical concentrations of Abacavir (20 µmol/L) induced leukocyte-endothelial cell interactions by specifically activating P2X7R, but the drug did not show affinity for the P2X7R ATP-binding site (site 1). CBV-TP levels were undetectable in Abacavir-treated cells, while those of ATP were unaltered. The effects of Abacavir were Apyrase-dependent, implying dependence on endogenous ATP. Exogenous ATP induced a profile of proinflammatory actions similar to Abacavir, but was not entirely P2X7R-dependent. Docking calculations suggested ATP-binding to sites 1 and 2, and Abacavir-binding only to allosteric site 2. A combination of concentrations of Abacavir (1 µmol/L) and ATP (0.1 µmol/L) that had no effect when administered separately induced leukocyte-endothelium interactions mediated by P2X7R and involving Connexin43 channels. Therefore, Abacavir acts as a positive allosteric modulator of P2X7R, turning low concentrations of endogenous ATP themselves incapable of stimulating P2X7R into a functional proinflammatory agonist of the receptor.This work was supported by Ministerio de Economía y Competitividad and the European Regional Development fund of the European Union (FEDER) (SAF2015–67678-R, RTI2018-094436-B-I00 and CTQ2017-88353-R), Ministerio de Sanidad y Consumo (CB06/04/0071, CIBERehd) and Generalitat Valenciana (PROMETEOII/2014/035 and PROMETEO 2018/141), along with an unrestricted grant from GILEAD S.L. VCD and ASL were funded by VALI + D program from Generalitat Valenciana (grants number ACIF/2015/316 and ACIF/2016/119, respectively) and PGM by FPU program from Ministerio de Educación, Cultura y Deporte (grant number FPU16/06064) and MABR by FPU program from Ministerio de Ciencia, Innovación y Universidades (grant number FPU17/04249).Peer reviewe

M2 Macrophages Activate WNT Signaling Pathway in Epithelial Cells: Relevance in Ulcerative Colitis

Macrophages, which exhibit great plasticity, are important components of the inflamed tissue and constitute an essential element of regenerative responses. Epithelial Wnt signalling is involved in mechanisms of proliferation and differentiation and expression of Wnt ligands by macrophages has been reported. We aim to determine whether the macrophage phenotype determines the expression of Wnt ligands, the influence of the macrophage phenotype in epithelial activation of Wnt signalling and the relevance of this pathway in ulcerative colitis. Human monocyte-derived macrophages and U937-derived macrophages were polarized towards M1 or M2 phenotypes and the expression of Wnt1 and Wnt3a was analyzed by qPCR. The effects of macrophages and the role of Wnt1 were analyzed on the expression of β-catenin, Tcf-4, c-Myc and markers of cell differentiation in a co-culture system with Caco-2 cells. Immunohistochemical staining of CD68, CD206, CD86, Wnt1, β-catenin and c-Myc were evaluated in the damaged and non-damaged mucosa of patients with UC. We also determined the mRNA expression of Lgr5 and c-Myc by qPCR and protein levels of β-catenin by western blot. Results show that M2, and no M1, activated the Wnt signaling pathway in co-culture epithelial cells through Wnt1 which impaired enterocyte differentiation. A significant increase in the number of CD206+ macrophages was observed in the damaged mucosa of chronic vs newly diagnosed patients. CD206 immunostaining co-localized with Wnt1 in the mucosa and these cells were associated with activation of canonical Wnt signalling pathway in epithelial cells and diminution of alkaline phosphatase activity. Our results show that M2 macrophages, and not M1, activate Wnt signalling pathways and decrease enterocyte differentiation in co-cultured epithelial cells. In the mucosa of UC patients, M2 macrophages increase with chronicity and are associated with activation of epithelial Wnt signalling and diminution in enterocyte differentiation

Putting the “bio” in “biotherapeutics”/checkpoints for biosimilars/application of biosimilars

The number of biosimilar medicines on the market is steadily increasing, due, in part, to patent expiration of several top-selling biologic medicines. These three e-learning modules discuss the basic concepts behind biosimilar medicines and highlight key regulatory considerations when using biosimilar medicines in medical practice

Looking beyond the Skin: Pathophysiology of Cardiovascular Comorbidity in Psoriasis and the Protective Role of Biologics

Psoriasis is a chronic systemic inflammatory disease associated with a higher incidence of cardiovascular disease, especially in patients with moderate to severe psoriasis. It has been estimated that severe psoriasis confers a 25% increase in relative risk of cardiovascular disease, regardless of traditional risk factors. Although the underlying pathogenic mechanisms relating psoriasis to increased cardiovascular risk are not clear, atherosclerosis is emerging as a possible link between skin and vascular affection. The hypothesis that the inflammatory cascade activated in psoriasis contributes to the atherosclerotic process provides the underlying basis to suggest that an anti-inflammatory therapy that improved atherosclerosis would also reduce the risk of MACEs. In this sense, the introduction of biological drugs which specifically target cytokines implicated in the inflammatory cascade have increased the expectations of control over the cardiovascular comorbidity present in psoriasis patients, however, their role in vascular damage processes remains controversial. The aim of this paper is to review the mechanistic link between psoriasis and cardiovascular disease development, as well as analyzing which of the biological treatments could also reduce the cardiovascular risk in these patients, fueling a growing debate on the modification of the general algorithm of treatment