Metformin: a cheap and well-tolerated drug that provides benefits for viral infections

OBJECTIVES

Insulin resistance in viral infections is common. We have explored the effectiveness of metformin for alleviating insulin resistance in HIV-infected patients and assessed the relevance of the ataxia-telangiectasia mutated (ATM) rs11212617 variant in the clinical response with the rationale that metformin modulates cellular bioenergetics in an ATM-dependent process.

METHODS

HIV-infected patients (n = 385) were compared with controls recruited from the general population (n = 300) with respect to the genotype distribution of the ATM rs11212617 variant and its influence on selected metabolic and inflammatory variables. We also followed up a subset of male patients with HIV and hepatitis C virus (HCV) coinfection (n = 47) who were not receiving antiviral treatment and for whom metformin was prescribed for insulin resistance, which tends to have a higher incidence and severity in coinfected patients.

RESULTS

Among the HIV-infected patients, human cytomegalovirus (91.9%) and HCV (62.3%) coinfections were frequent. Selected metabolic and/or inflammatory variables were significantly altered in infected patients. Treatment with metformin in HIV and HCV coinfected patients was well tolerated and significantly increased the sensitivity of peripheral tissues to insulin. The minor allele (C) of the rs11212617 variant was associated with treatment success and may affect the course of insulin resistance in response to metformin (odds ratio 1.21; 95% confidence interval 1.07-1.39; P = 0.005). There were no differences between treated and untreated patients in viral loads or variables measuring immune defence, indicating that toxicity is unlikely.

CONCLUSIONS

We provide novel data suggesting that identification of the ATM rs11212617 variant may be important in assessing the glycaemic response to metformin treatment for insulin resistance in HIV-infected patients.

Effects of therapeutic lifestyle changes on peripheral artery tonometry in patients with abdominal obesity

BACKGROUND AND AIMS

Abdominal obesity (AO) is associated with endothelial function (EF) alteration and increased global cardiovascular (CV) risk. Therapeutic lifestyle changes (TLSC) reduce CV risk, but the impact on EF assessed by peripheral artery tonometry (PAT) is unknown. In this study, we aimed to prospectively assess the effects of TLSC on EF measured by PAT in increased CV risk patients with AO.

METHODS AND RESULTS

150 patients with AO and moderate CV risk were randomized to groups receiving a one-year intervention of either conventional medical care (control group, CG) or an intensive TLSC program (intervention group, IG). Vascular studies (EF by PAT, intima-media thickness (IMT)) and lifestyle (LS) assessment were performed before and after intervention. The PAT ratio improved in the IG and worsened in the CG. The global CV risk was reduced (P = 0.017) in the IG due to a significant decrease in systolic blood pressure (P < 0.001), increase in HDL cholesterol and ApolipoproteinA1 (P = 0.013). More individuals in the IG than in the CG quit smoking (P = 0.001) and increased their physical activity (P = 0.014). The improvement in at least two LS components was associated with a PAT ratio increase (2.44 IC: 95% 0.99-6.00, P = 0.051). The PAT ratio increase determined less IMT progression (-1.1 IC: 95% 0.91-1.00, P = 0.053).

CONCLUSIONS

Good adherence to a TLSC program reduces global CV risk and determines PAT ratio improvement. The PAT ratio increase is the main determinant of lower IMT progression.

Continuous administration of polyphenols from aqueous rooibos (Aspalathus linearis) extract ameliorates dietary-induced metabolic disturbances in hyperlipidemic mice

The incidence of obesity and related metabolic diseases is increasing globally. Current medical treatments often fail to halt the progress of such disturbances, and plant-derived polyphenols are increasingly being investigated as a possible way to provide safe and effective complementary therapy. Rooibos (Aspalathus linearis) is a rich source of polyphenols without caloric and/or stimulant components. We have tentatively characterized 25 phenolic compounds in rooibos extract and studied the effects of continuous aqueous rooibos extract consumption in mice. The effects of this extract, which contained 25% w/w of total polyphenol content, were negligible in animals with no metabolic disturbance but were significant in hyperlipemic mice, especially in those in which energy intake was increased via a Western-type diet that increased the risk of developing metabolic complications. In these mice, we found hypolipemiant activity when given rooibos extract, with significant reductions in serum cholesterol, triglyceride and free fatty acid concentrations. Additionally, we found changes in adipocyte size and number as well as complete prevention of dietary-induced hepatic steatosis. These effects were not related to changes in insulin resistance. Among other possible mechanisms, we present data indicating that the activation of AMP-activated protein kinase (AMPK) and the resulting regulation of cellular energy homeostasis may play a significant role in these effects of rooibos extract. Our findings suggest that adding polyphenols to the daily diet is likely to help in the overall management of metabolic diseases.

The aqueous extract of Hibiscus sabdariffa calices modulates the production of monocyte chemoattractant protein-1 in humans

Diet supplementation and/or modulation is an important strategy to significantly improve human health. The search of plants as additional sources of bioactive phenolic compounds is relevant in this context. The aqueous extract of Hibiscus sabdariffa is rich in anthocyanins and other phenolic compounds including hydroxycitric and chlorogenic acids. Using this extract we have shown an effective protection of cultured peripheral blood mononuclear cells from the cellular death induced by H(2)O(2) and a significant role in the production of inflammatory cytokines. In vitro, the extract promotes the production of IL-6 and IL-8 and decreases the concentration of MCP-1 in supernatants in a dose-dependent manner. In humans, the ingestion of an acute dose of the extract (10g) was well tolerated and decreased plasma MCP-1 concentrations significantly without further effects on other cytokines. This effect was not due to a concomitant increase in the antioxidant capacity of plasma. Instead, its mechanisms probably involve a direct inhibition of inflammatory and/or metabolic pathways responsible for MCP-1 production, and may be relevant in inflammatory and chronic conditions in which the role of MCP-1 is well established. If beneficial effects are confirmed in patients, Hibiscus sabdariffa could be considered a valuable traditional herbal medicine for the treatment of chronic inflammatory diseases with the advantage of being devoid of caloric value or potential alcohol toxicity.

Pitfalls in measuring high-density lipoprotein cholesterol concentrations in HIV-infected patients

OBJECTIVES

HIV infection and its treatment are associated with dyslipidaemia and increased risk of cardiovascular disease. Accurate high-density lipoprotein (HDL) cholesterol values are necessary for the management of these abnormalities, but current methods have not been properly assessed in these patients. The aim of this study was to assess in HIV-infected patients the consistency and accuracy of a synthetic polymer/detergent homogeneous assay used to measure HDL cholesterol concentrations and to evaluate the impact of storage.

METHODS

HDL cholesterol was measured using a synthetic polymer/detergent homogeneous method in samples from HIV-infected patients and healthy subjects for each of the storage regimens: baseline, after 1 week at 4 degrees C, and after 12 months at -80 degrees C. The ultracentrifugation and precipitation assays were used for comparison.

RESULTS

Three out of every 20 samples from HIV-infected patients had discrepant HDL cholesterol values with respect to the ultracentrifugation method. Overestimation was associated with high C-reactive protein concentrations and underestimation with plasma gamma-globulin concentrations, an effect that was amplified by any of the storage conditions tested.

CONCLUSIONS

Caution is needed when using the synthetic polymer/detergent homogeneous method for direct measurement of HDL cholesterol concentrations in HIV-infected patients. This assay is of limited use in clinical trials in which frozen samples are analysed.