Tropical seaweeds improve cardiovascular and metabolic health of diet-induced obese and hypertensive rats

Seaweeds have been an important part of the diet of coastal populations in Asia possibly for millennia but only a few scattered coastal communities in Europe and the Americas have maintained these traditions. Our studies have investigated the potential of two tropical seaweeds grown commercially in Asia, Sarconema and Caulerpa spp., as functional foods for the reversal of metabolic syndrome and possible mechanisms. Sarconema spp. are a source of carrageenans used as thickening and gelling agents in foods, while Caulerpa spp. are consumed in Southeast Asia as low-energy foods with high contents of vitamins and minerals. For our studies, male Wistar rats were divided into groups in a 16-week protocol: corn starch diet-fed rats (C); C rats supplemented with 5% dried seaweed for the last 8 weeks; high-carbohydrate, high-fat diet-fed rats (H); and H rats supplemented with 5% dried seaweed for the last 8 weeks. H rats developed obesity, hypertension, dyslipidaemia, glucose intolerance, fatty liver and increased left ventricular collagen deposition, infiltration of inflammatory cells and plasma liver enzyme activities. Seaweed supplementation decreased body weight, abdominal and liver fat, systolic blood pressure, plasma lipid concentrations, plasma activities of liver enzymes and collagen deposition. Furthermore, seaweed supplementation modulated gut microbiota. Possible mechanisms for improved cardiovascular and metabolic health include a reduced infiltration of inflammatory cells into organs as well as an increased intake of fibre modulating gut microbiota composition. (This article belongs to the Proceedings of First International Electronic Conference on Nutrients, Microbiota and Chronic Disease

Caulerpa lentillifera (sea grapes) improves cardiovascular and metabolic health of rats with diet-induced metabolic syndrome

Caulerpa lentillifera (sea grapes) is widely consumed in South-East Asia as a low-energy food with high contents of vitamins and minerals. This study investigated dried sea grapes containing 16.6% insoluble fibre commercially produced in Vietnam as an intervention. We hypothesised that insoluble fibre is the primary metabolite that will reverse diet-induced metabolic syndrome. Male Wistar rats (n = 48) were randomly allocated to four groups in a 16 week protocol. Two groups were fed either corn starch (C) or high-carbohydrate, high-fat (H) diets for the full 16 weeks. The other two groups received C and H diets for eight weeks and then received C. lentillifera added to these diets for the final eight weeks (CCL and HCL, respectively). High-carbohydrate, high-fat diet-fed rats developed obesity, hypertension, dyslipidaemia, fatty liver disease and increased left ventricular collagen deposition. C. lentillifera supplementation in HCL rats decreased body weight, systolic blood pressure, plasma concentrations of total cholesterol and non-esterified fatty acids, inflammatory cells in heart and liver, and visceral adiposity. The Firmicutes to Bacteroidetes ratio decreased in the gut microbiota of HCL rats. Therefore, C. lentillifera attenuated cardiovascular and metabolic symptoms of metabolic syndrome in rats, possibly by preventing infiltration of inflammatory cells together with modulating gut microbiota

Nannochloropsis oceanica as a microalgal food intervention in diet-induced metabolic syndrome in rats

The microalgal genus Nannochloropsis has broad applicability to produce biofuels, animal feed supplements and other value-added products including proteins, carotenoids and lipids. This study investigated a potential role of N. oceanica in the reversal of metabolic syndrome. Male Wistar rats (n = 48) were divided into four groups in a 16-week protocol. Two groups were fed either corn starch or high-carbohydrate, high-fat diets (C and H, respectively) for the full 16 weeks. The other two groups received C and H diets for eight weeks and then received 5% freeze-dried N. oceanica in these diets for the final eight weeks (CN and HN, respectively) of the protocol. The H diet was high in fructose and sucrose, together with increased saturated and trans fats. H rats developed obesity, hypertension, dyslipidaemia, fatty liver disease and left ventricular fibrosis. N. oceanica increased lean mass in CN and HN rats, possibly due to the increased protein intake, and decreased fat mass in HN rats. Intervention with N. oceanica did not change cardiovascular, liver and metabolic parameters or gut structure. The relative abundance of Oxyphotobacteria in the gut microbiota was increased. N. oceanica may be an effective functional food against metabolic syndrome as a sustainable protein source

Metabolic effects of HCHF diet feeding.

<p>(A) Body weight of Wistar rats on CD or HCHF diet (n = 8). (B) Dorsal view of the rats showing the changes in the total abdominal length caused by the two diets after 16 weeks. ELISA analysis of pro-inflammatory (C) and (D) or anti-inflammatory (E) cytokines in serum (n = 6). Data were analyzed by two-tailed Student’s t test. All data are presented as mean ± SD. P < 0.05 (CD vs HCHF at two time point- week 8 and week 16) was considered to be significant. * = <i>p</i> <0.05.</p

Time-dependent histopathologic changes in the joint of HCHF diet-fed rats (8 and 16 weeks).

<p>Histological evaluation of the knee joints. Tissues were stained with safranin-O and fast green (A-B) to estimate the proteoglycan loss among the two time points in HCHF and CD groups. Scale bar = 20 μM. Extent of articular cartilage degradation was graded using Mankin scoring system (E). Safranin-O and fast green staining shows the difference in thickness of the synovial membrane following, (C)8, and (D)16-week HCHF diet Histological scoring showed increased synovial thickening in 8 and 16-week-diet rats (F). Data were analyzed by Mann-Whitney test. All data are presented as mean ± SD. <i>P</i> < 0.05 (HCHF at week 8 vs HCHF at week 16) was considered to be significant. * = <i>p</i> <0.05. n = 8 per each group at each collection time point. Scale bar = 20 μM.</p

Synovial fluid of 16-week HCHF rats alters macrophage polarization and chondrocyte differentiation in vitro.

<p>Relative qPCR analysis of pro-inflammatory M1-like (A) or anti-inflammatory M2-like (B) genes in BMDMs after synovial fluid stimulation. ELISA analysis of pro-inflammatory (C) or anti-inflammatory (D) cytokines in conditioned medium. (E) Relative qPCR analysis of MMP13, ADAMTS5, COL10, ACAN and SOX9 in micromass cultured ACCs after 7 days of synovial fluid stimulation. (F) GAG release in supernatant of ACCs after synovial fluid stimulation at day 3 and day 7. Data were analyzed by two-tailed Student’s <i>t</i> test. All data are presented as mean ± SD, <i>P</i> < 0.05 was considered to be significant. * = <i>p</i> <0.05. n = 5 independent samples.</p

Brown seaweed Sargassum siliquosum as an intervention for diet-induced obesity in male wistar rats

The therapeutic potential of Sargassum siliquosum grown in Australian tropical waters was tested in a rat model of metabolic syndrome. Forty-eight male Wistar rats were divided into four groups of 12 rats and each group was fed a different diet for 16 weeks: corn starch diet (C); high-carbohydrate, high-fat diet (H) containing fructose, sucrose, saturated and trans fats; and C or H diets with 5% S. siliquosum mixed into the food from weeks 9 to 16 (CS and HS). Obesity, hypertension, dyslipidaemia, impaired glucose tolerance, fatty liver and left ventricular fibrosis developed in H rats. In HS rats, S. siliquosum decreased body weight (H, 547 ± 14; HS, 490 ± 16 g), fat mass (H, 248 ± 27; HS, 193 ± 19 g), abdominal fat deposition and liver fat vacuole size but did not reverse cardiovascular and liver effects. H rats showed marked changes in gut microbiota compared to C rats, while S. siliquosum supplementation increased gut microbiota belonging to the family Muribaculaceae. This selective increase in gut microbiota likely complements the prebiotic actions of the alginates. Thus, S. siliquosum may be a useful dietary additive to decrease abdominal and liver fat depositio

M1 macrophage negatively affects chondrogenic differentiation of chondrocytes.

<p>Relative qPCR analysis of pro-inflammatory M1-like (A) or anti-inflammatory M2-like (B) genes in CD14+ macrophages after cytokine treatment. ELISA analysis of pro-inflammatory (C) or anti-inflammatory (D) cytokines in conditioned medium. Relative qPCR analysis of MMP2 (E), MMP13 (F), RUNX2 (G), ADAMTS5 (H), SOX9 (I), and ACAN (J) mRNA levels in chondrocytes treated with M1 CM or M2 CM. (K) GAG release in supernatant of chondrocytes treated with 50% M1/M2 CM treatment for 3 and 7 days. Data were analyzed by two-tailed Student’s <i>t</i> test. Values represent the mean ± SD of experimental triplicates, <i>P</i> < 0.05 was considered to be significant. * = <i>p</i> <0.05. n = 5 independent samples.</p

Macrophage-like cells increase in inflamed synovium of 16-week HCHF rats and are predominately iNOS+.

<p>(A) Representative immunohistochemical and immunofluorescence analyses of synovial tissues from CD or HCHF diet rats with anti-CD68, anti-iNOS or anti-Arg1. (B) Quantitative assessment of CD68+, iNOS+ or Arg1+ cells of inflamed synovium. Total positive cells per 100 cells were used as a standard measure to quantify. (C, D) qPCR analysis of pro-inflammatory M1-like (C) or anti-inflammatory M2-like (D) genes in synovium after diet stimulation. Data were analyzed by two-tailed Student’s <i>t</i> test. All data are presented as mean ± SD, <i>P</i> < 0.05 was considered to be significant. * = <i>p</i> <0.05. n = 5. Scale bar = 20 μM.</p

Dietary intake and body composition in CD and HCHF rats.

<p>Dietary intake and body composition in CD and HCHF rats.</p