scholarly journals Pharmacological and Metabolic Significance of Bile Acids in Retinal Diseases

Biomolecules ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 292
Author(s):  
Alice Win ◽  
Amanda Delgado ◽  
Ravirajsinh N. Jadeja ◽  
Pamela M. Martin ◽  
Manuela Bartoli ◽  
...  

Bile acids (BAs) are amphipathic sterols primarily synthesized from cholesterol in the liver and released in the intestinal lumen upon food intake. BAs play important roles in micellination of dietary lipids, stimulating bile flow, promoting biliary phospholipid secretion, and regulating cholesterol synthesis and elimination. Emerging evidence, however, suggests that, aside from their conventional biological function, BAs are also important signaling molecules and therapeutic tools. In the last decade, the therapeutic applications of BAs in the treatment of ocular diseases have gained great interest. Despite the identification of BA synthesis, metabolism, and recycling in ocular tissues, much remains unknown with regards to their biological significance in the eye. Additionally, as gut microbiota directly affects the quality of circulating BAs, their analysis could derive important information on changes occurring in this microenvironment. This review aims at providing an overview of BA metabolism and biological function with a focus on their potential therapeutic and diagnostic use for retinal diseases.

1968 ◽  
Vol 22 (2) ◽  
pp. 237-246 ◽  
Author(s):  
Aileen M. Lennox ◽  
A. K. Lough ◽  
G. A. Garton

1. Total lipids were extracted from digesta obtained from the rumen, abomasum and upper small intestine (jejunum) of each of four slaughtered sheep. The lipids were fractionated into unesterified fatty acids, neutral lipids and phospholipids and the proportional contribution of each fraction to the total fatty acids was determined.2. The contribution made by phospholipids to the total fatty acids in the digesta showed a marked increase in the samples from the small intestine compared with those from the rumen and abomasum. This increase was apparently due to the presence of biliary phospholipids.3. Total lipids and conjugated bile acids were extracted from sheep bile, the lipids were fractionated and their fatty-acid composition was determined. Phospholipids predominated and these consisted mainly of phosphatidylcholine, together with some lysophosphatidylcholine.4. Both phospholipids contained significant amounts of unsaturated C18 components which could account, at least in part, for the previously reported increament to the proportion of these acids in the digesta when it enters the upper jejunum.5. The overall fatty acid compositions of the two biliary phospholipids were very similar and, in common with other naturally occurring phosphatidylcholines, the fatty acids present in position 2 of the phosphatidylcholine of bile were found to consist almost entirely of unsaturated components.6. Total lipids and conjugated bile acids were extracted from samples of digesta obtained from three sheep with cannulas in different positions in the jejunum. Analysis of the lipids indicated that biliary phospholipids, in particular phosphatidylcholine, underwent progressive hydrolysis in the intestinal lumen.7. The distribution of conjugated bile acids, unesterified fatty acids and phospholipids between the solid (particulate) and liquid (micellar) phases of the intestinal digesta was determined. These chyme constituents were, for the most part, associated with the particulate matter and thus, at any given time, it appears that only a small fraction of the total fatty acids is available for absorption in micellar form. It is suggested that the micellar solubilization of fatty acids may be facilitated by the presence of lysophosphatidylcholine.


2022 ◽  
Vol 23 (2) ◽  
pp. 726
Author(s):  
Alicia A. Brunet ◽  
Alan R. Harvey ◽  
Livia S. Carvalho

Inherited retinal diseases (IRDs) are a leading cause of blindness. To date, 260 disease-causing genes have been identified, but there is currently a lack of available and effective treatment options. Cone photoreceptors are responsible for daylight vision but are highly susceptible to disease progression, the loss of cone-mediated vision having the highest impact on the quality of life of IRD patients. Cone degeneration can occur either directly via mutations in cone-specific genes (primary cone death), or indirectly via the primary degeneration of rods followed by subsequent degeneration of cones (secondary cone death). How cones degenerate as a result of pathological mutations remains unclear, hindering the development of effective therapies for IRDs. This review aims to highlight similarities and differences between primary and secondary cone cell death in inherited retinal diseases in order to better define cone death mechanisms and further identify potential treatment options.


2020 ◽  
Vol 85 (11) ◽  
pp. 3806-3814
Author(s):  
Jisun H.J. Lee ◽  
Guddadarangavvanahally K. Jayaprakasha ◽  
Carlos A. Avila ◽  
Kevin M. Crosby ◽  
Bhimanagouda S. Patil

1993 ◽  
Vol 264 (6) ◽  
pp. G1118-G1125 ◽  
Author(s):  
C. E. Chandler ◽  
L. M. Zaccaro ◽  
J. B. Moberly

Bile acids are efficiently recovered from the intestinal lumen by a Na(+)-dependent transport process that is localized in the ileal enterocyte brush-border membrane. To establish a cell culture model for this process, we examined the Na+ dependence of cholyltaurine (C-tau; taurocholate) transport across monolayers of differentiated Caco-2 cells grown on permeable filter inserts. Transport of [3H]C-tau was Na+ dependent (> 20-fold stimulation), saturable, and time linear for at least 60 min. The apparent Michaelis constant of [3H]C-tau transport was approximately 65 microM, and the maximal transport rate was approximately 800 pmol.min-1.mg protein-1. Transport of [3H]C-tau in the apical-to-basolateral direction was 17-fold greater than transport in the reverse direction. Lowered incubation temperature, various metabolic inhibitors, and various unlabeled bile acids inhibited [3H]C-tau transport. Caco-2 cells thus transport bile acids in a manner similar to that described for ileal brush-border membrane vesicles and isolated ileal enterocytes and are therefore an appropriate model for studying the molecular basis of ileal bile acid transport.


Cells ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 2594
Author(s):  
Yue Ruan ◽  
Tobias Böhmer ◽  
Subao Jiang ◽  
Adrian Gericke

The retina is a part of the central nervous system, a thin multilayer with neuronal lamination, responsible for detecting, preprocessing, and sending visual information to the brain. Many retinal diseases are characterized by hemodynamic perturbations and neurodegeneration leading to vision loss and reduced quality of life. Since catecholamines and respective bindings sites have been characterized in the retina, we systematically reviewed the literature with regard to retinal expression, distribution and function of alpha1 (α1)-, alpha2 (α2)-, and beta (β)-adrenoceptors (ARs). Moreover, we discuss the role of the individual adrenoceptors as targets for the treatment of retinal diseases.


Cells ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 288 ◽  
Author(s):  
Alessandra Stacchiotti ◽  
Gaia Favero ◽  
Luigi Fabrizio Rodella

Skeletal muscle disorders are dramatically increasing with human aging with enormous sanitary costs and impact on the quality of life. Preventive and therapeutic tools to limit onset and progression of muscle frailty include nutrition and physical training. Melatonin, the indole produced at nighttime in pineal and extra-pineal sites in mammalians, has recognized anti-aging, anti-inflammatory, and anti-oxidant properties. Mitochondria are the favorite target of melatonin, which maintains them efficiently, scavenging free radicals and reducing oxidative damage. Here, we discuss the most recent evidence of dietary melatonin efficacy in age-related skeletal muscle disorders in cellular, preclinical, and clinical studies. Furthermore, we analyze the emerging impact of melatonin on physical activity. Finally, we consider the newest evidence of the gut–muscle axis and the influence of exercise and probably melatonin on the microbiota. In our opinion, this review reinforces the relevance of melatonin as a safe nutraceutical that limits skeletal muscle frailty and prolongs physical performance.


2006 ◽  
Vol 24 (18_suppl) ◽  
pp. 4513-4513 ◽  
Author(s):  
F. M. Calais Da Silva ◽  
F. Calais Da Silva ◽  
A. Bono ◽  
M. Brausi ◽  
P. Whelan ◽  
...  

4513 Background: Patients with locally advanced or metastatic prostate cancer cannot be cured with any of the therapeutic tools available today. Methods: After an initial induction treatment of three months, with CPA 200 mg for two week’s and then monthly depot injections of LHRH analogue (decaptyl) plus 200 mg of CPA daily in 766 patients with locally advanced or metastatic prostate cancer, 626 patients whose PSA decreased below 4 or to 80% below their initial value, were randomised to intermittent or continuous therapy. Results: Among the 314 patients on Intermittent therapy, 50% have been off therapy for at least 52 weeks following the initial LHRH therapy, 29% have been off therapy for over 36 months. For the 197 patients whose PSA went down to ≤ 2 ng/ml, the median time off therapy was 74 weeks. When these patients returned to therapy they had a median of 14 weeks of treatment, followed by a second period off therapy, median 70 weeks. Patients with PSA < 2 ng/ml have spent a median of 82% of their time receiving no therapy.After a median follow up of 51 months, 321 patients have died: 162 in the Intermittent arm compared to 159 in the Continuous arm (HR = 1.03 [95% confidence interval 0.83, 1.28; p = 0.79]). Estimated survival at 5 years was 53.8% in the Intermittent Group and 51.0% in the Continuous Group.Subjective or Objective progression was noted in 224 patients, 113 on the intermittent arm and 111 on the continuous arm with a hazard ratio of 1.09 (95% CI 0.84, 1.42), p=0.52. The main differences in quality of life between the two arms of the study were confined to sexual function.Sexual activity was significantly greater (p<0.01) in the intermittent arm with 41% of men reporting sexual activity at 9 months, 40% at 15 months and 35% at 21 months.The most commonly reported side effects were hot flushes, were more frequently among those on Continuous Therapy, 30% of continuous patients compared to 20% of intermittent patients, p < 0.01. Conclusions: There is no evidence that Intermittent therapy leads to a significantly elevated hazard of dying (p = 0.79) or to a greater subjective or objective progression (p = 0.52) and with less impact on quality of live and less medication, patients with PSA < 2 ng/ml on randomisation have spent a median of 82% of their time receiving no therapy. We think that intermittent therapy is an option to use in regular clinic. No significant financial relationships to disclose.


2018 ◽  
Vol 84 (10) ◽  
Author(s):  
Heidi Doden ◽  
Lina A. Sallam ◽  
Saravanan Devendran ◽  
Lindsey Ly ◽  
Greta Doden ◽  
...  

ABSTRACTBile acids are important cholesterol-derived nutrient signaling hormones, synthesized in the liver, that act as detergents to solubilize dietary lipids. Bile acid 7α-dehydroxylating gut bacteria generate the toxic bile acids deoxycholic acid and lithocholic acid from host bile acids. The ability of these bacteria to remove the 7-hydroxyl group is partially dependent on 7α-hydroxysteroid dehydrogenase (HSDH) activity, which reduces 7-oxo-bile acids generated by other gut bacteria. 3α-HSDH has an important enzymatic activity in the bile acid 7α-dehydroxylation pathway. 12α-HSDH activity has been reported for the low-activity bile acid 7α-dehydroxylating bacteriumClostridium leptum; however, this activity has not been reported for high-activity bile acid 7α-dehydroxylating bacteria, such asClostridium scindens,Clostridium hylemonae, andClostridium hiranonis. Here, we demonstrate that these strains express bile acid 12α-HSDH. The recombinant enzymes were characterized from each species and shown to preferentially reduce 12-oxolithocholic acid to deoxycholic acid, with low activity against 12-oxochenodeoxycholic acid and reduced activity when bile acids were conjugated to taurine or glycine. Phylogenetic analysis suggests that 12α-HSDH is widespread amongFirmicutes,Actinobacteriain theCoriobacteriaceaefamily, and human gutArchaea.IMPORTANCE12α-HSDH activity has been established in the medically important bile acid 7α-dehydroxylating bacteriaC. scindens,C. hiranonis, andC. hylemonae. Experiments with recombinant 12α-HSDHs from these strains are consistent with culture-based experiments that show a robust preference for 12-oxolithocholic acid over 12-oxochenodeoxycholic acid. Phylogenetic analysis identified novel members of the gut microbiome encoding 12α-HSDH. Future reengineering of 12α-HSDH enzymes to preferentially oxidize cholic acid may provide a means to industrially produce the therapeutic bile acid ursodeoxycholic acid. In addition, a cholic acid-specific 12α-HSDH expressed in the gut may be useful for the reduction in deoxycholic acid concentration, a bile acid implicated in cancers of the gastrointestinal (GI) tract.


Author(s):  
Mallika Prem Senthil ◽  
Jyoti Khadka ◽  
Jagjit Singh Gilhotra ◽  
Sumu Simon ◽  
Konrad Pesudovs

2015 ◽  
Vol 308 (7) ◽  
pp. G634-G642 ◽  
Author(s):  
Linda S. Zhang ◽  
Min Xu ◽  
Qing Yang ◽  
Robert O. Ryan ◽  
Philip Howles ◽  
...  

Apolipoprotein A-V (apoA-V), a liver-synthesized apolipoprotein discovered in 2001, strongly modulates fasting plasma triglycerides (TG). Little is reported on the effect of apoA-V on postprandial plasma TG, an independent predictor for atherosclerosis. Overexpressing apoA-V in mice suppresses postprandial TG, but mechanisms focus on increased lipolysis or clearance of remnant particles. Unknown is whether apoA-V suppresses the absorption of dietary lipids by the gut. This study examines how apoA-V deficiency affects the steady-state absorption and lymphatic transport of dietary lipids in chow-fed mice. Using apoA-V knockout (KO, n = 8) and wild-type (WT, n = 8) lymph fistula mice, we analyzed the uptake and lymphatic transport of lipids during a continuous infusion of an emulsion containing [3H]triolein and [14C]cholesterol. ApoA-V KO mice showed a twofold increase in3H ( P < 0.001) and a threefold increase in14C ( P < 0.001) transport into the lymph compared with WT. The increased lymphatic transport was accompanied by a twofold reduction ( P < 0.05) in mucosal3H, suggesting that apoA-V KO mice more rapidly secreted [3H]TG out of the mucosa into the lymph. ApoA-V KO mice also produced chylomicrons more rapidly than WT ( P < 0.05), as measured by the transit time of [14C]oleic acid from the intestinal lumen to lymph. Interestingly, apoA-V KO mice produced a steadily increasing number of chylomicron particles over time, as measured by lymphatic apoB output. The data suggest that apoA-V suppresses the production of chylomicrons, playing a previously unknown role in lipid metabolism that may contribute to the postprandial hypertriglyceridemia associated with apoA-V deficiency.


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