Intracellular prostaglandin E2 contributes to hypoxia-induced proximal tubular cell death.

Proximal tubular cells (PTC) are particularly vulnerable to hypoxia-induced apoptosis, a relevant factor for kidney disease. We hypothesized here that PTC death under hypoxia is mediated by cyclo-oxygenase (COX-2)-dependent production of prostaglandin E2 (PGE2), which was confirmed in human proximal tubular HK-2 cells because hypoxia (1% O2)-induced apoptosis (i) was prevented by a COX-2 inhibitor and by antagonists of prostaglandin (EP) receptors and (ii) was associated to an increase in intracellular PGE2 (iPGE2) due to hypoxia-inducible factor-1α-dependent transcriptional up-regulation of COX-2. Apoptosis was also prevented by inhibitors of the prostaglandin uptake transporter PGT, which indicated that iPGE2 contributes to hypoxia-induced apoptosis (on the contrary, hypoxia/reoxygenation-induced PTC death was exclusively due to extracellular PGE2). Thus, iPGE2 is a new actor in the pathogenesis of hypoxia-induced tubular injury and PGT might be a new therapeutic target for the prevention of hypoxia-dependent lesions in renal diseases.

Comprehensive metabolomic study of the response of HK-2 cells to hyperglycemic hypoxic diabetic-like milieu.

Diabetic nephropathy (DN) is the leading cause of chronic kidney disease. Although hyperglycaemia has been determined as the most important risk factor, hypoxia also plays a relevant role in the development of this disease. In this work, a comprehensive metabolomic study of the response of HK-2 cells, a human cell line derived from normal proximal tubular epithelial cells, to hyperglycemic, hypoxic diabetic-like milieu has been performed. Cells simultaneously exposed to high glucose (25 mM) and hypoxia (1% O2) were compared to cells in control conditions (5.5 mM glucose/18.6% O2) at 48 h. The combination of advanced metabolomic platforms (GC-TOF MS, HILIC- and CSH-QExactive MS/MS), freely available metabolite annotation tools, novel databases and libraries, and stringent cut-off filters allowed the annotation of 733 metabolites intracellularly and 290 compounds in the extracellular medium. Advanced bioinformatics and statistical tools demonstrated that several pathways were significantly altered, including carbohydrate and pentose phosphate pathways, as well as arginine and proline metabolism. Other affected metabolites were found in purine and lipid metabolism, the protection against the osmotic stress and the prevention of the activation of the ß-oxidation pathway. Overall, the effects of the combined exposure of HK-cells to high glucose and hypoxia are reasonably compatible with previous in vivo works.

Time-series proteomic study of the response of HK-2 cells to hyperglycemic, hypoxic diabetic-like milieu.

During diabetes, renal proximal tubular cells (PTC) are exposed to a combination of high glucose and hypoxic conditions, which plays a relevant role in the development of diabetic kidney disease (DKD). In this work, a time-series proteomic study was performed to analyse the effect of a diabetic-like microenvironment induced changes on HK-2 cells, a human cell line derived from normal proximal tubular epithelial cells. Cells simultaneously exposed to high glucose (25 mM) and hypoxia (1% O2) were compared to cells in control conditions for up to 48 h. Diabetic conditions increased the percentage of death cells after 24 and 48 h, but no differences in the protein/cell ratio were found. The relative protein quantification using dimethyl-labeling and UHPLC-MS/MS analysis allowed the identification of 317, 296 and 259 proteins at 5, 24 and 48 h, respectively. The combination of statistical and time expression profile analyses indicated an increased expression of proteins involved in glycolysis, and a decrease of cytoskeletal-related proteins. The exposure of HK-2 cells to high glucose and hypoxia reproduces some of the effects of diabetes on PTC and, with the limitations inherent to in vitro studies, propose new mechanisms and targets to be considered in the management of DKD.

Author Correction: Mechanism and Consequences of The Impaired Hif-1α Response to Hypoxia in Human Proximal Tubular HK-2 Cells Exposed to High Glucose.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Retinoic acid receptor-beta prevents cisplatin-induced proximal tubular cell death.

Cisplatin's toxicity in renal tubular epithelial cells limits the therapeutic efficacy of this antineoplastic drug. In cultured human proximal tubular HK-2 cells (PTC) a prostaglandin uptake transporter (PGT)-dependent increase in intracellular prostaglandin E2 (iPGE2) mediates cisplatin's toxicity (i.e. increased cell death and loss of cell proliferation) so that it is prevented by PGT inhibitors. Here we found in cisplatin-treated PTC that 4,4'-diisothiocyanostilbene-2,2'-disulfonic acid (DIDS), a PGT inhibitor, prevented cisplatin's toxicity but not the increase in iPGE2. Because expression of retinoic acid receptor-ß (RAR-ß) is dependent on iPGE2 and because RAR-ß is a regulator of cell survival and proliferation, we hypothesized that RAR-ß might mediate the protective effect of DIDS against cisplatin's toxicity in PTC. Our results confirmed this hypothesis because: i) protection of PTC by DIDS was abolished by RAR-ß antagonist LE-135; ii) DIDS increased the expression of RAR-ß in PTC and prevented its decrease in cisplatin-treated PTC but not in cisplatin-treated human cervical adenocarcinoma HeLa cells in which DIDS failed to prevent cisplatin's toxicity; iii) while RAR-ß expression decreased in cisplatin-treated PTC, RAR-ß over-expression prevented cisplatin's toxicity. RAR-ß agonist CH55 or RAR pan-agonist all-trans retinoic acid did not prevent cisplatin's toxicity, which suggests that RAR-ß does not protect PTC through activation of gene transcription. In conclusion, RAR-ß might be a new player in cisplatin-induced proximal tubular injury and the preservation of its expression in proximal tubules through treatment with DIDS might represent a novel strategy in the prevention of cisplatin's nephrotoxicity without compromising cisplatin's chemotherapeutic effect on cancer cells.

Abordaje de la cesación tabáquica de un paciente desde la farmacia comunitaria. Programa 'CESAR' / Approaching patients' smoking cessation as early as in community pharmacies. The 'CESAR' Program

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Mechanism and Consequences of The Impaired Hif-1α Response to Hypoxia in Human Proximal Tubular HK-2 Cells Exposed to High Glucose.

Renal hypoxia and loss of proximal tubular cells (PTC) are relevant in diabetic nephropathy. Hypoxia inhibits hypoxia-inducible factor-1α (HIF-1α) degradation, which leads to cellular adaptive responses through HIF-1-dependent activation of gene hypoxia-responsive elements (HRE). However, the diabetic microenvironment represses the HIF-1/HRE response in PTC. Here we studied the mechanism and consequences of impaired HIF-1α regulation in human proximal tubular HK-2 cells incubated in hyperglycemia. Inhibition at different levels of the canonical pathway of HIF-1α degradation did not activate the HIF-1/HRE response under hyperglycemia, except when proteasome was inhibited. Further studies suggested that hyperglycemia disrupts the interaction of HIF-1α with Hsp90, a known cause of proteasomal degradation of HIF-1α. Impaired HIF-1α regulation in cells exposed to hyperglycemic, hypoxic diabetic-like milieu led to diminished production of vascular endothelial growth factor-A and inhibition of cell migration (responses respectively involved in tubular protection and repair). These effects, as well as impaired HIF-1α regulation, were reproduced in normoglycemia in HK-2 cells incubated with microparticles released by HK-2 cells exposed to diabetic-like milieu. In summary, these results highlight the role of proteasome-dependent mechanisms of HIF-1α degradation on diabetes-induced HK-2 cells dysfunction and suggest that cell-derived microparticles may mediate negative effects of the diabetic milieu on PTC.

Apoptosis and cell proliferation in proximal tubular cells exposed to apoptotic bodies. Novel pathophysiological implications in cisplatin-induced renal injury.

The therapeutic efficacy of the antineoplastic drug cisplatin is limited by its nephrotoxicity, which affects particularly to proximal tubular cells (PTC). Cisplatin-induced cytotoxicity appears to be multifactorial and involves inflammation, oxidative stress as well as apoptosis. We have recently shown that the cyclo-oxygenase-2 (COX-2)/intracellular prostaglandin E2 (iPGE2)/EP receptor pathway mediates the apoptotic effect of cisplatin on human proximal tubular HK-2 cells. Here, we studied the effects on HK-2 cells of apoptotic bodies (ABs) generated after treatment of HK-2 cells with cisplatin. We found that ABs inhibited cell growth, induced apoptosis and increased COX-2 expression and iPGE2 in ABs-recipient HK-2 cells. Inhibition of the COX-2/iPGE2/EP receptor pathway in these cells prevented the effects of ABs without interfering with their internalization. Interestingly, 2nd generation ABs (i.e. ABs released by cells undergoing apoptosis upon treatment with ABs) did not trigger apoptosis in naïve HK-2 cells, and stimulated cell proliferation through the COX-2/iPGE2/EP receptor pathway. These results suggest that ABs, through iPGE2-dependent mechanisms, might have a relevant role in the natural history of cisplatin-induced acute kidney failure because they contribute first to the propagation of the noxious effects of cisplatin to non-injured PTC and then to the promotion of the proliferative tubular response required for proximal tubule repair. Since iPGE2 also mediates both cisplatin-induced HK-2 cell apoptosis, intervention in the COX-2/iPGE2/EP receptor pathway might provide us with new therapeutic avenues in patients with cisplatin-induced acute kidney injury.

Medicina herbal china ofertada en páginas web en español: calidad de la información y riesgos / Information quality and health risks in Spanish-language retail websites for Chinese herbal medicine

Objetivo: El auge de la venta en Internet propicia el acceso a productos naturales potencialmente tóxicos y la rápida difusión de la información, no necesariamente veraz, que los proveedores ofrecen al consumidor acerca de sus propiedades. El objetivo del presente trabajo ha sido analizar en páginas web en español de venta de medicina herbal china la calidad de la información ofrecida al consumidor y los posibles riesgos derivados de su consumo. Métodos: I) Búsqueda en Google España de sitios web de venta de medicina herbal china y posterior evaluación de la información sobre las propiedades y consumo seguro de los productos ofertados. II) Identificación en los sitios web de plantas III) Cuantificación de las retiradas de productos de medicina herbal china por la Agencia Española de Medicamentos y Productos Sanitarios (AEMPS). Resultados: 1) Sólo un tercio de las 30 páginas web localizadas cumple con la legislación vigente, ya que las demás incluyen indicaciones terapéuticas occidentales como reclamo para la venta de medicina herbal china en España 2) Cinco páginas aportan información sobre consumo seguro 3) Dos páginas ofertan plantas potencialmente tóxicas y 4) Un importante porcentaje de productos retirados por la AEMPS corresponde a medicina herbal china adulterada con sibutramina, sildenafilo o sus derivados. Conclusión: Nuestros resultados indican que existen motivos suficientes que aconsejan la creación por parte de las autoridades españolas de un sitio web que asesore a quienes pretenden utilizar Internet para comprar medicina herbal china y así permitir que los usuarios tomen decisiones estando bien informados (AU)

Objective: The growing use of purchase online via Internet retailers favours the access to potentially toxic natural products. It also contributes to the quick dissemination of the claims made by the retailers on efficacy and safety, these claims being not always based upon reliable information. Here, we have conducted an online search to find Spanish-language retail websites for Chinese herbal medicine and we have analysed them for the quality of product information and the potential health risks. Methods: I) Online search in Google España to find Spanish-language retail websites for Chinese herbal medicine in which we analysed both the claims regarding possible health benefits and adequate safe use indications II) Identification of potentially toxic herbs in the websites III) Quantification of Chinese herbal medicines withdrawn by the Agencia Española de Medicamentos y Productos Sanitarios (AEMPS). Results: 1) Only one third of the 30 Spanish-language retail websites found which sell Chinese herbal medicine observe the law, given that the other websites include illegal Western disease claims as marketing tools, 2) Five websites provide some safety information, 3) Two websites offer potentially toxic herbs and 4) Chinese herbal medicine adulterated with sibutramine, silfenafil or their analogues make a considerable percentage of the total products withdrawn by the AEMPS. Conclusion: Online health seekers should be warned about misinformation on retail websites for Chinese herbal medicine and directed to a Spanish government Web site for guidance in safely navigating the Internet for buying Chinese herbal medicine (AU)

[Information quality and health risks in Spanish-language retail websites for Chinese herbal medicine]. / Medicina herbal china ofertada en páginas web en español: calidad de la información y riesgos.

OBJECTIVE: The growing use of purchase online via Internet retailers favours the access to potentially toxic natural products. It also contributes to the quick dissemination of the claims made by the retailers on efficacy and safety, these claims being not always based upon reliable information. Here, we have conducted an online search to find Spanish-language retail websites for Chinese herbal medicine and we have analysed them for the quality of product information and the potential health risks. METHODS: i) Online search in Google España to find Spanish-language retail websites for Chinese herbal medicine in which we analysed both the claims regarding possible health benefits and adequate safe use indications ii) Identification of potentially toxic herbs in the websites iii) Quantification of Chinese herbal medicines withdrawn by the Agencia Española de Medicamentos y Productos Sanitarios (AEMPS). RESULTS: 1) Only one third of the 30 Spanish-language retail websites found which sell Chinese herbal medicine observe the law, given that the other websites include illegal Western disease claims as marketing tools, 2) Five websites provide some safety information, 3) Two websites offer potentially toxic herbs and 4) Chinese herbal medicine adulterated with sibutramine, silfenafil or their analogues make a considerable percentage of the total products withdrawn by the AEMPS. CONCLUSION: Online health seekers should be warned about misinformation on retail websites for Chinese herbal medicine and directed to a Spanish government Web site for guidance in safely navigating the Internet for buying Chinese herbal medicine.

The effect of the European traditional use directive on the register of herbal medicinal products in Spain / Efecto en España de la directiva Europea de uso tradicional sobre el registro de medicamentos a base de plantas

Background: Directive 2004/24/EC, which came into force in 2011, created new regulatory requirements for traditional herbal medicines (THM). This study compared the Spanish THM registry before and after the Directive came fully into force in 2011. Methods: We consulted the herbal medicinal plant and drug catalogues (General Council of the Official Colleges of Pharmacists), the website of the European Medicines Agency (EMA), and retail web sites. Results: Of 315 THM (from 39 companies) licensed in Spain in 2010, only 48 (10 companies) remained licensed in 2013, mainly due to their withdrawal: the EMA had received just 123 applications from Spain and at least 34% formerly licensed THM had shifted to the less strictly regulated food sector, while up to 54% might have disappeared from the market. However, there is still a significant presence of retail websites making illegal health claims. Conclusion: In Spain, the public health benefits of the Directive 2004/24/EC might be less than expected (AU)

Antecedentes: En 2011 entró totalmente en vigor la Directiva 2004/24/CE, que impone nuevos requerimientos a los medicamentos tradicionales a base de plantas. Este trabajo analiza el efecto sobre su registro en España. Métodos: Se consultaron los catálogos de plantas medicinales y de medicamentos (CGCOF), la página web de la Agencia Europea del Medicamento (EMA) y sitios de venta en Internet. Resultados: De los 315 medicamentos a base de plantas autorizados en 2010, procedentes de 39 compañías; solo quedaban 48 (10 compañías) en 2013 por renuncia de la mayoría: sólo 123 solicitudes fueron recibidas a la EMA y al menos un 34% se pasó al sector de alimentación (menos estrictamente regulado). Hasta un 54% podría no comercializarse actualmente. Sin embargo, existe una presencia significativa de sitios web anunciando ilegalmente propiedades saludables para sus productos. Conclusión: Los beneficios de la Directiva 2004/24/CE para la salud pública española podrían ser menos de los esperados (AU)

The effect of the European traditional use directive on the register of herbal medicinal products in Spain.

BACKGROUND: Directive 2004/24/EC, which came into force in 2011, created new regulatory requirements for traditional herbal medicines (THM). This study compared the Spanish THM registry before and after the Directive came fully into force in 2011. METHODS: We consulted the herbal medicinal plant and drug catalogues (General Council of the Official Colleges of Pharmacists), the website of the European Medicines Agency (EMA), and retail web sites. RESULTS: Of 315 THM (from 39 companies) licensed in Spain in 2010, only 48 (10 companies) remained licensed in 2013, mainly due to their withdrawal: the EMA had received just 123 applications from Spain and at least 34% formerly licensed THM had shifted to the less strictly regulated food sector, while up to 54% might have disappeared from the market. However, there is still a significant presence of retail websites making illegal health claims. CONCLUSION: In Spain, the public health benefits of the Directive 2004/24/EC might be less than expected.