Lara Milian

Effect of boldine, secoboldine, and boldine methine on angiotensin II‐induced neurtrophil recruitment in vivo

Angiotensin‐II (Ang‐II) has inflammatory activity and is involved in different diseases associated with the cardiovascular system. This study has evaluated the effect of boldine (B), and two phenanthrene alkaloids semisynthesized by us, secoboldine (SB) and boldine methine (BM), on Ang‐II‐induced neutrophil recruitment. Intraperitoneal administration of 1 nM Ang‐II induced significant neutrophil accumulation, which was maximal at 4–8 h. BM inhibited neutrophil infiltration into the peritoneal cavity at 4 h and 8 h by 73% and 77%, respectively, SB at 8 h by 55%, and B had no effect on this response. Although BM inhibited the release of cytokine‐inducible neutrophil chemoattractant/keratinocyte‐derived chemokine, macrophage inflammatory protein‐2 (MIP‐2), and platelet‐activating factor (PAF) elicited by Ang‐II, SB only reduced the release of MIP‐2 after 4 h of its administration. Sixty‐minute superfusion of the rat mesentery with 1 nM Ang‐II induced a significant increase in the leukocyte‐endothelial cell interactions and P‐selectin up‐regulation, which were inhibited by 1 μM BM and SB. The generation of reactive oxygen species (ROS) in endothelial cells stimulated with Ang‐II was inhibited significantly by the three alkaloids tested. BM also diminished Ang‐II‐induced interleukin‐8 release from endothelial cells and blocked the PAF receptor on human neutrophils (concentration of the compound needed to produce 50% inhibition value: 28.2 μM). Therefore, BM is a potent inhibitor of Ang‐II‐induced neutrophil accumulation in vivo. This effect appears to be mediated through inhibition of CXC chemokine and PAF release, ROS scavenging activity, and blockade of the PAF receptor. Thus, it may have potential therapeutic interest for the control of neutrophil recruitment that occurs in inflammation associated with elevated levels of Ang‐II.

Effect of two phenanthrene alkaloids on angiotensin II‐induced leukocyte–endothelial cell interactions in vivo

The present study has evaluated the effect of two phenanthrene alkaloids, uvariopsine and stephenanthrine, on angiotensin II (Ang‐II)‐induced leukocyte–endothelial cell interactions in vivo and the mechanisms involved in their activity. Intravital microscopy within the rat mesenteric microcirculation was used. A 60 min superfusion with 1 nM Ang‐II induced a significant increase in the leukocyte–endothelial cell interactions that were completely inhibited by 1 μM uvariopsine cosuperfusion. A lower dose of 0.1 μM significantly reduced Ang‐II‐induced leukocyte adhesion by 75%. When Ang‐II was cosuperfused with 1 and 0.1 μM stephenanthrine, Ang‐II‐induced leukocyte responses were significantly diminished. A lower dose of 0.01 μM only affected Ang‐II‐induced leukocyte adhesion. Both alkaloids inhibited Ang‐II‐induced endothelial P‐selectin upregulation and the generation of reactive oxygen species (ROS) in endothelial cells stimulated with Ang‐II, in fMLP‐stimulated human neutrophils (PMNs) and in the hypoxanthine–xanthine oxidase system. However, cyclic AMP levels in PMNs stimulated with fMLP were not affected. Uvariopsine and stephenanthrine inhibited PAF‐induced elevations in intracellular calcium levels in PMNs (IC50 values: 15.1 and 6.1 μM respectively) and blocked the binding of [3H]PAF to these leukocytes. They also reduced PAF‐induced increases in intracellular levels of superoxide anion and hydrogen peroxide. In conclusion, stephenanthrine and uvariopsine are potent inhibitors of Ang‐II‐induced leukocyte accumulation in vivo. This effect appears to be mediated through ROS scavenging activity and blockade of PAF receptor. Thus, they have potential therapeutic interest for the control of leukocyte recruitment that occurs in cardiovascular disease states in which Ang‐II is involved.

PGC-1α induction in pulmonary arterial hypertension.

Idiopathic Pulmonary arterial hypertension (IPAH) is characterized by the obstructive remodelling of pulmonary arteries, and a progressive elevation in pulmonary arterial pressure (PAP) with subsequent right-sided heart failure and dead. Hypoxia induces the expression of peroxisome proliferator activated receptor γ coactivator-1α (PGC-1α) which regulates oxidative metabolism and mitochondrial biogenesis. We have analysed the expression of PGC-1α, cytochrome C (CYTC), superoxide dismutase (SOD), the total antioxidant status (TAS) and the activity of glutathione peroxidase (GPX) in blood samples of IPAH patients. Expression of PGC-1α was detected in IPAH patients but not in healthy volunteers. The mRNA levels of SOD were lower in IPAH patients compared to controls (3.93 ± 0.89 fold change). TAS and GPX activity were lower too in patients compared to healthy donors, (0.13 ± 0.027 versus 0.484 ± 0.048 mM and 56.034 ± 10.37 versus 165.46 ± 11.38 nmol/min/mL, resp.). We found a negative correlation between expression levels of PGC-1α and age, PAP and PVR, as well as a positive correlation with CI, PaO2, mRNA levels of CYTC and SOD, TAS and GPX activity. These results taken together are indicative of the possible role of PGC-1α as a potential biomarker of the progression of IPAH.

Synthesis and reactive oxygen species scavenging activity of halogenated alkaloids from boldine

Six halogenated alkaloids have been semi-synthesized from natural boldine as starting material. Their antioxidant activity toward reactive oxygen species (ROS) generation by neutrophils stimulated with N-formyl-methionyl-leucyl-phenylalanine and in the hypoxanthine–xanthine oxidase system was evaluated. Most of the alkaloids synthesized inhibited ROS generation in both systems in a concentration-dependent manner. The alkaloids with phenolic substituents displayed more powerful anti-oxidative activity than those containing methoxylated groups. None of the alkaloids assayed had any effect on xanthine oxidase activity. Therefore, halogenated phenanthrene alkaloids can become in promising candidates for the development of novel and potent anti-inflammatory drugs.

In Vivo Articular Cartilage Regeneration Using Human Dental Pulp Stem Cells Cultured in an Alginate Scaffold: A Preliminary Study

Osteoarthritis is an inflammatory disease in which all joint-related elements, articular cartilage in particular, are affected. The poor regeneration capacity of this tissue together with the lack of pharmacological treatment has led to the development of regenerative medicine methodologies including microfracture and autologous chondrocyte implantation (ACI). The effectiveness of ACI has been shown in vitro and in vivo, but the use of other cell types, including bone marrow and adipose-derived mesenchymal stem cells, is necessary because of the poor proliferation rate of isolated articular chondrocytes. In this investigation, we assessed the chondrogenic ability of human dental pulp stem cells (hDPSCs) to regenerate cartilage in vitro and in vivo. hDPSCs and primary isolated rabbit chondrocytes were cultured in chondrogenic culture medium and found to express collagen II and aggrecan. Both cell types were cultured in 3% alginate hydrogels and implanted in a rabbit model of cartilage damage. Three months after surgery, significant cartilage regeneration was observed, particularly in the animals implanted with hDPSCs. Although the results presented here are preliminary, they suggest that hDPSCs may be useful for regeneration of articular cartilage.

Gene Mutations in Primary Ciliary Dyskinesia Related to Otitis Media

Otitis media with effusion (OME) is the most common cause of conductive hearing loss in children and is strongly associated with primary ciliary dyskinesia (PCD). Approximately half of the children with PCD require otolaryngology care, posing a major problem in this population. Early diagnosis of PCD is critical in these patients to minimise the collateral damage related to OME. The current gold standard for PCD diagnosis requires determining ciliary structure defects by transmission electron microscopy (TEM) or clearly documenting ciliary dysfunction via digital high-speed video microscopy (DHSV). Although both techniques are useful for PCD diagnosis, they have limitations and need to be supported by new methodologies, including genetic analysis of genes related to PCD. In this article, we review classical and recently associated mutations related to ciliary alterations leading to PCD, which can be useful for early diagnosis of the disease and subsequent early management of OME.

Human platelet-rich plasma improves the nesting and differentiation of human chondrocytes cultured in stabilized porous chitosan scaffolds:

The clinical management of large-size cartilage lesions is difficult due to the limited regenerative ability of the cartilage. Different biomaterials have been used to develop tissue engineering substitutes for cartilage repair, including chitosan alone or in combination with growth factors to improve its chondrogenic properties. The main objective of this investigation was to evaluate the benefits of combining activated platelet-rich plasma with a stabilized porous chitosan scaffold for cartilage regeneration. To achieve this purpose, stabilized porous chitosan scaffolds were prepared using freeze gelation and combined with activated platelet-rich plasma. Human primary articular chondrocytes were isolated and cultured in stabilized porous chitosan scaffolds with and without combination to activated platelet-rich plasma. Scanning electron microscopy was used for the morphological characterization of the resulting scaffolds. Cell counts were performed in hematoxylin and eosin–stained sections, and type I and II collagen expression was evaluated using immunohistochemistry. Significant increase in cell number in activated platelet-rich plasma/stabilized porous chitosan was found compared with stabilized porous chitosan scaffolds. Chondrocytes grown on stabilized porous chitosan expressed high levels of type I collagen but type II was not detectable, whereas cells grown on activated platelet rich plasma/stabilized porous chitosan scaffolds expressed high levels of type II collagen and type I was almost undetectable. In summary, activated platelet-rich plasma increases nesting and induces the differentiation of chondrocytes cultured on stabilized porous chitosan scaffolds.

Tenofovir-induced toxicity in renal proximal tubular epithelial cells: involvement of mitochondria

Objective: In-vivo studies suggest that mitochondria is involved in tenofovir (TFV)-induced renal toxicity, but the underlying mechanisms are still unclear. The aim of the present study was to assess the effects of TFV and its prodrug, TFV disoproxil fumarate, on mitochondrial function and cell survival/viability in a renal proximal tubular cell line. Design and methods: We evaluated parameters of cellular proliferation/survival (cell count, cell cycle, viability) and mitochondrial function (oxygen consumption, mitochondrial membrane potential, reactive oxygen species production) in NRK-52E cells. Intracellular TFV was measured by HPLC and expression of antioxidant genes was analysed by real-time PCR. Results: Similar intracellular levels of TFV were reached with lower concentrations of the prodrug than of the drug, and correlated directly with a decrease in cell number. Both compounds inhibited proliferation and compromised mitochondrial function by decreasing mitochondrial membrane potential and increasing oxygen consumption and mitochondrial superoxide production. Altered oxidative status was confirmed by the overexpression of antioxidant genes. Conclusions: Intracellular accumulation of TFV induces mitochondrial toxicity in an in-vitro renal model and alters cell proliferation and viability. Our findings call for caution regarding the use of this nucleotide analogue reverse transcriptase inhibitor in patients with other risk factors that compromise mitochondrial function in the kidney.