Dietary supplementation with docosahexanoic acid (DHA) increases red blood cell membrane flexibility in mice with sickle cell disease.

Humans and mice with sickle cell disease (SCD) have rigid red blood cells (RBCs). Omega-3 fatty acids, such as docosahexanoic acid (DHA), may influence RBC deformability via incorporation into the RBC membrane. In this study, sickle cell (SS) mice were fed natural ingredient rodent diets supplemented with 3% DHA (DHA diet) or a control diet matched in total fat (CTRL diet). After 8weeks of feeding, we examined the RBCs for: 1) stiffness, as measured by atomic force microscopy; 2) deformability, as measured by ektacytometry; and 3) percent irreversibly sickled RBCs on peripheral blood smears. Using atomic force microscopy, it is found that stiffness is increased and deformability decreased in RBCs from SS mice fed CTRL diet compared to wild-type mice. In contrast, RBCs from SS mice fed DHA diet had markedly decreased stiffness and increased deformability compared to RBCs from SS mice fed CTRL diet. Furthermore, examination of peripheral blood smears revealed less irreversibly sickled RBCs in SS mice fed DHA diet as compared to CTRL diet. In summary, our findings indicate that DHA supplementation improves RBC flexibility and reduces irreversibly sickled cells by 40% in SS mice. These results point to potential therapeutic benefits of dietary omega-3 fatty acids in SCD.

Diet influences expression of autoimmune-associated genes and disease severity by epigenetic mechanisms in a transgenic mouse model of lupus.

OBJECTIVE: Lupus flares occur when genetically predisposed individuals encounter appropriate environmental agents. Current evidence indicates that the environment contributes by inhibiting T cell DNA methylation, causing overexpression of normally silenced genes. DNA methylation depends on both dietary transmethylation micronutrients and ERK-regulated DNA methyltransferase 1 (DNMT-1) levels. We used transgenic mice to study the effect of interactions between diet, DNMT-1 levels, and genetic predisposition on the development and severity of lupus. METHODS: A doxycycline-inducible ERK defect was bred into lupus-resistant (C57BL/6) and lupus-susceptible (C57BL/6 × SJL) mouse strains. Doxycycline-treated mice were fed a standard commercial diet for 18 weeks and then switched to a transmethylation micronutrient-supplemented (MS) or -restricted (MR) diet. Disease severity was assessed by examining anti-double-stranded DNA (anti-dsDNA) antibody levels, the presence of proteinuria and hematuria, and by histopathologic analysis of kidney tissues. Pyrosequencing was used to determine micronutrient effects on DNA methylation. RESULTS: Doxycycline induced modest levels of anti-dsDNA antibodies in C57BL/6 mice and higher levels in C57BL/6 × SJL mice. Doxycycline-treated C57BL/6 × SJL mice developed hematuria and glomerulonephritis on the MR and standard diets but not the MS diet. In contrast, C57BL/6 mice developed kidney disease only on the MR diet. Decreasing ERK signaling and methyl donors also caused demethylation and overexpression of the CD40lg gene in female mice, consistent with demethylation of the second X chromosome. Both the dietary methyl donor content and the duration of treatment influenced methylation and expression of the CD40lg gene. CONCLUSION: Dietary micronutrients that affect DNA methylation can exacerbate or ameliorate disease in this transgenic murine lupus model, and contribute to lupus susceptibility and severity through genetic-epigenetic interactions.

The contribution of body protein to the supply of energy in starved newborn piglets is not preferentially suppressed by intravenous provision of glucose and fat.

Newborn piglets were used to study body protein preservation because it is critical to the survival of premature infants. Quantitative estimates of endogenous fuel use were obtained from 12 to 72 h of age in male piglets. Of the 40 piglets used (1300 +/- 205 g, mean +/- SD), 16 served as a 12-h-old body composition reference (R), 16 were starved (S) and received water only, and 8 received supplemental energy (E), obtaining 70% [210 kJ/(kg x d)] of their resting energy requirement as an i.v. mixture of glucose and Intralipid (65:35 energy ratio). Urine was collected continuously from the bladder via an umbilical urachal catheter. Total body water, glycogen, lipid, ash, and Kjeldahl-N were determined on whole-pig homogenates. Comparative slaughter was used to estimate the disappearance of body constituents of S and E pigs from 12 to 72 h of age. Midpoint body weight was used in these calculations. Supplemental energy decreased use of all body energy sources as indicated by the decrease in body dry matter disappearance, 41.6 +/- 8.8 vs. 25.5 +/- 5.9 g/kg (P = 0.0021) and protein (urinary N excretion), 995 +/- 508 vs. 329 +/- 135 mg/kg (P = 0.0119) over 60 h. Supplemental energy did not preferentially spare the percentage of the resting energy expenditure supplied by endogenous body protein (protein 37.6% +/- 9.6 vs. 41.7% +/- 10.4; lipid 25.7% +/- 5.2 vs. 20% +/- 4.1; glycogen 36.8% +/- 7.5 vs. 38.3% +/- 9.9; S vs. E) because it made up approximately 40% of the total in food-deprived and supplemented piglets.