Plasma kinetics of an LDL-like non-protein nanoemulsion and transfer of lipids to high-density lipoprotein (HDL) in patients with rheumatoid arthritis

Androgen deprivation therapy improves the in vitro capacity of high-density lipoprotein (HDL) to receive cholesterol and other lipids in patients with prostate carcinoma

Background

Androgen deprivation therapy (ADT) is widely used in the treatment of testosterone-dependent prostate carcinomas. ADT often increases plasma LDL and HDL cholesterol and triglycerides. The aim was to test whether ADT changes the transfer of lipids to HDL, an important aspect of this metabolism and HDL protective functions, and related parameters.

Methods

Sixteen volunteers with advanced prostate carcinoma submitted to pharmacological ADT or orchiectomy had plasma collected shortly before and after 6 months of ADT. In vitro transfer of lipids to HDL was performed by incubating plasma with donor emulsion containing radioactive lipids by 1 h at 37 °C. After chemical precipitation of apolipoprotein B-containing lipoprotein, the radioactivity of HDL fraction was counted.

Results

ADT reduced testosterone to nearly undetectable levels and markedly diminished PSA. ADT increased the body weight but glycemia, triglycerides, LDL and HDL cholesterol, HDL lipid composition and CETP concentration were unchanged. However, ADT increased the plasma unesterified cholesterol concentration (48 ± 12 vs 56 ± 12 mg/dL, p = 0.019) and LCAT concentration (7.15 ± 1.81 vs 8.01 ± 1.55μg/mL, p = 0.020). Transfer of unesterified (7.32 ± 1.09 vs 8.18 ± 1.52%, p < 0.05) and esterified cholesterol (6.15 ± 0.69 vs 6.94 ± 1.29%, p < 0.01) and of triglycerides (6.37 ± 0.43 vs 7.18 ± 0.91%, p < 0.001) to HDL were increased after ADT. Phospholipid transfer was unchanged.

Conclusion

Increase in transfer of unesterified and esterified cholesterol protects against cardiovascular disease, as shown previously, and increased LCAT favors cholesterol esterification and facilitates the reverse cholesterol transport. Thus, our results suggest that ADT may offer anti-atherosclerosis protection by improving HDL functional properties. This could counteract, at least partially, the eventual worse effects on plasma lipids.

Aerobic Training in Young Men Increases the Transfer of Cholesterol to High Density Lipoprotein In Vitro: Impact of High Density Lipoprotein Size

Exercise training not only improves the plasma lipid profile but also reduces risk of developing coronary heart disease. We investigate whether plasma lipids and high density lipoprotein (HDL) metabolism are affected by aerobic training and whether the high-density lipoprotein cholesterol (HDL-C) levels at baseline influence exercise-induced changes in HDL. Seventy-one male sedentary volunteers were evaluated and allocated in two subgroups, according to the HLD-C levels (< or >40 mg/dL). Participants underwent an 18-week aerobic training period. Blood was sampled before and after training for biochemical analysis. Plasma lipids, apolipoproteins, HDL diameter, and VO₂ peak were determined. Lipid transfers to HDL were determined in vitro by incubating plasma samples with a donor lipid artificial nanoemulsion. After the 18-week period of aerobic training, the VO₂ peak increased, while the mean body mass index (BMI) decreased. HDL-C concentration was higher after the training period, but low-density lipoprotein cholesterol (LDL-C) and non-HDL-C did not change. The transfer of esterified cholesterol and phospholipids was greater after exercise training, but the triacylglycerol and unesterified cholesterol transfers were unchanged. The HDL particle diameter increased after aerobic training in all participants. When the participants were separated in low-HDL and normal-HDL groups, the postaerobic exercise increment in HDL-C was higher in the low-HDL group, while the transfer of esterified cholesterol was lower. In conclusion, aerobic exercise training increases the lipid transfers to HDL, as measured by an in vitro method, which possibly contributes to the classical elevation of the HDL-C associated with training.

Lipid-Based Nanoparticles as a Potential Delivery Approach in the Treatment of Rheumatoid Arthritis

Rheumatoid arthritis (RA), a chronic and joint-related autoimmune disease, results in immune dysfunction and destruction of joints and cartilages. Small molecules and biological therapies have been applied in a wide variety of inflammatory disorders, but their utility as a therapeutic agent is limited by poor absorption, rapid metabolism, and serious side effects. To improve these limitations, nanoparticles, which are capable of encapsulating and protecting drugs from degradation before they reach the target site in vivo, may serve as drug delivery systems. The present research proposes a platform for different lipid nanoparticle approaches for RA therapy, taking advantage of the newly emerging field of lipid nanoparticles to develop a targeted theranostic system for application in the treatment of RA. This review aims to present the recent major application of lipid nanoparticles that provide a biocompatible and biodegradable delivery system to effectively improve RA targeting over free drugs via the presentation of tissue-specific targeting of ligand-controlled drug release by modulating nanoparticle composition.

High-density lipoprotein function in rheumatoid arthritis

PURPOSE OF REVIEW

Patients with rheumatoid arthritis (RA) have accelerated atherosclerosis despite the appearance of having a less atherogenic lipid profile; however, lipoprotein function rather than concentration may be a better indicator of atherosclerotic risk. The purpose of this review is to summarize recent findings concerning HDL function in patients with RA.

RECENT FINDINGS

Two major activities of HDL, its antioxidant and cholesterol efflux functions have been examined in RA. HDL antioxidant capacity is inversely associated with inflammation and RA disease activity; however, there is no clear consensus if antioxidant capacity is altered significantly in RA compared with control study participants. Moreover, despite numerous studies there is no consensus whether HDL cholesterol efflux capacity is significantly altered in RA compared with control study participants or influenced by inflammation or disease activity.

SUMMARY

Additional studies will be valuable to consolidate existing data and find consensus. Moreover, studies evaluating the impact of various HDL functions on cardiovascular disease in RA are needed.