Dietary nucleotides may influence the humoral immunity in immunocompromised children

5'-Ribonucleotides production using 5'-phosphodiesterase from spent malt roots

Abstract 5'-ribonucleotides are high value-added molecules widely used in the food and pharmaceutical industries because of their bioactive properties. The present work aims to produce a composition of 5’-ribonucleotides using spent brewer’s yeast as cheap source of RNA, and barley malt rootlets as cheap source of 5'-phosphodiesterase (5'-PDE). This is a very promising and innovative strategy because both spent yeast and malt rootles are residues of the brewing process and are closely linked in a cycle that until now is not yet commercially exploited due to lack of studies. Our results showed that extraction of 5’-PDE was mainly influenced by the fineness of the rootlets and amount of extraction solvent (water). The main molecules formed during RNA hydrolysis were 5’-ribonucleotides, which represented 85.86% of the total hydrolyzed molecules. Finally, the results of the proposed approach can generate a new perspective for the brewing industry regarding the management of its wastes, generating from them products of high added value and with a wide range of applications.

The potential for enhancement of immunity in cats by dietary supplementation

This study was conducted to examine the potential benefits of dietary supplementation on the feline immune system. Forty three cats (8 or 9 per group) were fed a low protein control diet (22.7% DM basis), the same diet supplemented with yeast-derived nucleotides, salmon oil or l-arginine or a commercial moist high protein diet (53.0% DM basis) for a period of five weeks. The low protein diets were formulated using a commercial moist diet base with added fat and starch and fed ad libitum, along with water. Specific immune assays showed that supplementation with arginine caused a significant enhancement of lymphocyte proliferative responses to the T-cell mitogen PHA after 35 days (P=0.018), while supplementation with either nucleotides or salmon oil resulted in significant enhancement after both 14 (P=0.0048, P<0.0001 respectively) and 35 days (both P<0.0001). Dietary supplementation with arginine, nucleotides or salmon oil each led to significant increases in blood leucocyte phagocytic activity after both 14 (P=0.0003, P=0.0077, P<0.0001 respectively) and 35 days (P<0.0001). This indicates that a number of dietary ingredients have the ability to modulate the immune system of healthy cats possibly resulting in a greater ability to fight infection and disease.

Utilization of salmon milt DNA against UV damage

We examined the effect of ultraviolet (UV) irradiation on the UV spectra and radical scavenging activity of DNA strands and found that the absorption spectra of salmon milt DNA was extended up to about 350 nm after ultraviolet C (UVC, 100-280 nm) irradiation with 300 kJ/m(2). The UV B (UVB, 280-315 nm) protection ability of UVC-irradiated salmon milt DNA for a single-stranded target DNA (19-mer) was further studied. The percentage of damaged target DNA after 50 kJ/m(2) of UVB irradiation in the presence of UVC-irradiated salmon milt DNA, UVC-unirradiated salmon milt DNA, and 2-phenylbenzimidazole sulfonic acid was estimated to be 24.6%, 27.0%, and 18.9%, respectively. Moreover, the ultraviolet A (UVA, 315-400 nm)/UVB ratio and critical wavelength of natural (UVC-unirradiated) salmon milt DNA were estimated to be 0.13 and 313 nm, respectively, whereas those of the UVC-irradiated salmon milt DNA were 0.34 and 375 nm, respectively. Interestingly, the value of 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity in UVC-irradiated salmon milt DNA was about five times higher than that of UVC-unirradiated salmon milt DNA. These results indicate that the UVC-irradiated salmon milt DNA could be useful as a protector against a wide range of UV light from UVC approximately UVA.

Bovine glycomacropeptide induces cytokine production in human monocytes through the stimulation of the MAPK and the NF-kappaB signal transduction pathways

BACKGROUND AND PURPOSE

Bovine glycomacropeptide (BGMP) is a natural milk peptide that is produced naturally in the gastrointestinal tract during digestion. Glycomacropepide has intestinal anti-inflammatory activity, but the mechanism of action is unknown. Here we have characterized the effects of BGMP on monocytes.

EXPERIMENTAL APPROACH

We have used human THP-1 cells as an in vitro monocyte model. The effect of BGMP on the secretion of tumour necrosis factor (TNF), interleukin (IL)-1beta and IL-8 was assessed, as well as the involvement of the NF-kappaB and MAP kinase signalling pathways. The stimulatory effect of BGMP was also tested in human peripheral blood monocytes.

KEY RESULTS

BGMP up-regulated the secretion of TNF, IL-1beta and IL-8 in a concentration-dependent fashion. The biological activity was exerted by the intact peptide, because cytokine secretion was not affected by protease inhibitors. The secretion of IL-8 and specially TNF and IL-1beta was blocked by PD98059, SP600125, SB203580 and Bay11-7082, suggesting the involvement of the MAP kinases p38, c-Jun N-terminal kinase and ERK and particularly the NF-kappaB pathway, although IL-8 secretion was independent of p38. BGMP was shown to elicit the phosphorylation of IkappaB-alpha and the nuclear translocation of the NF-kappaB subunits p50 and p65. The effect of BGMP on cytokine secretion was validated in human primary blood monocytes.

CONCLUSIONS AND IMPLICATIONS

BGMP stimulates human monocytes, operating via MAP kinase and NF-kappaB pathways. BGMP may exert an indirect intestinal anti-inflammatory effect by potentiating host defences against invading microorganisms.

The possible role of human milk nucleotides as sleep inducers

Breast-milk contains a potent mixture of diverse components, such as the non-protein nitrogen fraction which includes nucleotides, whose variation in levels is evident throughout lactation. In addition, these substances play an important role in sleep homeostasis. In the present study, human milk samples were analyzed using a capillary electrophoresis system. The rhythmicity of each nucleotide was studied by cosinor analysis. It was found that the nucleotides 5'AMP, 5'GMP, 5'CMP, and 5'IMP have significant (P < 0.05) circadian rhythms, the acrophases of the first two being during the night, and of the latter two during the day. While 5'UMP did not show a clear circadian rhythm, there was an increase in its levels at night. In conclusion, the rise in nocturnal levels of 5'AMP, 5'GMP, and 5'UMP could be involved in inducing the 'hypnotic' action of breast-milk at night in the infant.

Effect of nucleotide supplementation on lymphocyte DNA damage induced by dietary oxidative stress in pigs

The aim of the present study was to evaluate the effect of nucleotide supplementation on the oxidative stress induced by a high proportion of dietary polyunsaturated fatty acids ( PUFAs) in pigs. Twenty-four male growing pigs were penned individually and after an adaptation period divided into three groups. All groups received isocaloric daily rations composed of a basal diet supplemented with either: starch (CONT), linseed oil (LIN) and LIN and nucleotides (LIN + NUC). The experimental period lasted 21 days. Oxidative stress was evaluated by measuring the degree of lymphocyte nuclear DNA damage, the urine malondialdehyde ( MDA) excretion rate, erythrocyte glutathione peroxidase concentration and the total anti-oxidant status of plasma. Malondialdehyde concentrations in the blood and MDA urinary excretion rates were higher (P< 0·01) in animals supplemented with LIN and LIN + NUC compared with CONT animals. The degree of DNA damage in the LIN-supplemented animals was also higher (P< 0·01). Compared with the LIN-supplemented animals, nucleotide supplementation reduced (P< 0·01) the degree of DNA damage in lymphocytes to the level of the CONT group. Erythrocyte glutathione peroxidase concentration and plasma total anti-oxidant status were similar across treatments. The results of this experiment indicate that nucleotide supplementation effectively eliminates the genotoxic effects of high PUFA intakes on blood lymphocytes and demonstrates new evidence for the immunonutritive effect of nucleotides.

Ribonucleotides: conditionally essential nutrients shown to enhance immune function and reduce diarrheal disease in infants

It remains a goal of pediatric nutrition to provide optimal nourishment for infants who are not fed human milk. Investigators have attempted to emulate the composition and functionality of human milk, the gold standard for infant nutrition. These efforts began with the analysis of milk components and continued with assessments of biological effects that culminated in clinical studies in infants. This chapter summarizes the path that researchers followed to study ribonucleotides and their role in infant nutrition. Based on analytical methods for the quantification of ribonucleotides in human milk, investigators assessed their potential impact on the immune systems of infants and looked for concomitant mechanistic explanations. These inquiries evolved into clinical trials in which ribonucleotide-supplemented formula performance was compared with that of non-supplemented formulas and with human milk. This chapter intends to summarize an area of pediatric nutrition that has yielded both enlightening evidence and seemingly contradictory data.

Effect of dietary nucleotide supplementation on growth and immune function in term infants: a randomized controlled trial

OBJECTIVE

To examine the effect of nucleotide (NT)-supplemented cow's milk-based formula on growth and biochemical indices of immune function in healthy infants.

DESIGN

Randomized controlled trial (RCT) of formula-fed term infants allocated to control formula with an innate level of NT at 10 mg/l (n = 102), or formula fortified with NT at 33.5 mg/l (n = 98). A parallel group of 125 breastfed infants followed the same protocol as a reference.

OUTCOME MEASURES

Growth was assessed at enrolment, 7 weeks, 4 months and 7 months of age. Natural killer cell activity, cytokine production and lymphocyte subpopulations were assessed at 7 weeks of age. Antibody responses to diphtheria toxoid, tetanus toxoid and Haemophilus influenzae type b (Hib) immunizations were measured at 7 months of age.

RESULTS

NT supplementation did not influence the growth of formula fed infants or any markers of immunity measured at 7 weeks of age. Antibody responses to tetanus toxoid were higher in the NT-supplemented group (n = 68) compared with the control group (n = 70) at 7 months of age (median (5th, 95% percentile): 1.57(0.42, 3.43) vs 1.01(0.41, 4.66) IU/ml, P < 0.03). A difference between treatments was seen in response to diphtheria toxoid but this effect disappeared when adjusted for hepatitis B immunization at birth. There was no effect of treatment on antibody responses to Hib immunization.

CONCLUSIONS

Supplementation of formulas with NT at 33.5 mg/l resulted in a modest improvement in antibody response consistent with RCTs that used higher levels of NT supplementation. Whether this translates to clinical benefits in well-nourished infants requires further study.

SPONSORSHIP

Supported by a grant from Wyeth Nutrition. Dr Makrides was supported by an RD Wright Fellowship from the National Health and Medical Research Council of Australia and Dr Gibson was partially supported by the MS McLeod Research Trust and a Senior Research Fellowship from the National Health and Medical Research Council of Australia.

Effect of dietary ribonucleotides on infant immune status. Part 1: Humoral responses

The objective of this study was to further explore previously identified effects of supplemental ribonucleotides on infant immune status as measured by antibody responses to routine infant immunizations. Infants were randomized to a milk-based formula with (FN, n = 138) or without (F, n = 147) 72 mg ribonucleotides/L. A cohort of human milk-fed (HMF, n = 192) infants was also followed. Subjects were given Haemophilus influenzae type b (Hib), diphtheria tetanus acellular pertussis, and oral poliovirus vaccinations at 2, 4, and 6 mo of age, and specific antibody responses were assessed at 2, 6, 7, and 12 mo. Growth and safety data were also monitored. Using a two-group repeated measures analysis (RMA), FN-fed infants had significantly higher poliovirus type 1 neutralizing antibody (PV-VN1) responses than F-fed infants (p = 0.045). Using three-group RMA, PV-VN1 responses in HMF infants were not different from FN-fed infants, while HMF-fed infant PV-VN1 responses were significantly higher than F-fed infants at 6 (p = 0.0004) and 12 mo (p = 0.0001). FN-fed infants had responses to Hib Farr, diphtheria, tetanus toxoid, oral poliovirus-specific IgA, and PV-VN3 not significantly different from those of F and HMF infants. Growth, gastrointestinal tolerance, and adverse events were equivalent among the three groups. The FN-associated increase in PV-VN1 response and nonstatistically significant trends toward increased Hib and diphtheria antibody responses were consistent with observations from earlier studies, indicating immune benefits of nucleotide supplementation of infant formula.

Determination of total potentially available nucleosides in human milk from Asian women

OBJECTIVE

The objective was to measure the total potentially available nucleosides (TPAN) in breast milk from Asian women.

METHODS

One hundred sixty milk samples were collected from 135 healthy, lactating women in Hong Kong, the Philippines, and Singapore at four stages of lactation: colostrum (1 to 3 days postpartum), transitional (7 to 10 days postpartum), early mature (28 to 35 days postpartum), and late mature (90 to 100 days postpartum). Samples were pooled by site and stage of lactation before analysis.

RESULTS

The mean TPAN concentration was 203 microM/L (69.4 mg/L corrected for recovery). Average TPAN concentrations were 171.9 microM/L in colostrum, 208.1 microM/L in transitional milk, 221.6 microM/L in early mature milk, and 210.6 microM/L in late mature milk, with no notable differences between countries. The major sources of nucleosides were RNA (43.3% of TPAN) and free nucleotides (39.9% of TPAN). The average percentages of cytidine, uridine, guanosine, and adenosine monophosphates were 44.5%, 23.1%, 16.5%, and 16.1% of TPAN, respectively. The sources of nucleosides and percentages of nucleotide bases were similar for all stages of lactation. Over 91% of the TPAN was present in the non-cellular component except in colostrum.

CONCLUSIONS

The average TPAN level in Asian women is similar to that in European and American women, and free nucleotides in human milk represent less than half of the TPAN.

Effect of nucleotides on diarrhea and immune responses in healthy term infants in Taiwan

OBJECTIVES

The aim of this study was to compare the effects of an infant formula fortified with nucleotides (NF) with those of a control formula (CF) on the incidence of diarrhea, respiratory tract infections (RTIs), and immune responses in healthy term infants.

METHODS

This 12-month, double-blind study was conducted on 1- to 7-day-old infants randomized to receive NF or CF exclusively until 12 weeks of age, and fed the assigned formula with solid food until 12 months. NF was supplemented with 72 mg/L of nucleotides, based on the total potentially available nucleotide content of human milk. Subjects were evaluated within 1 week of birth, at 4 weeks, and every 4 weeks thereafter until 48 weeks of age. The primary outcome variable was the incidence of diarrhea. Secondary variables included RTIs, serum immunoglobulin concentrations, and response to hepatitis B vaccine.

RESULTS

Compared with subjects fed CF (n = 170), those fed NF (n = 166) had a trend toward reduced risk of diarrhea from 8 to 48 weeks of age and a significantly lower risk of 25.4% (P = 0.05) between 8 and 28 weeks. NF subjects had significantly higher serum immunoglobulin A concentrations ( P < 0.05) throughout the 48-week study. The NF group had an increased risk of upper RTIs, the same incidence of lower RTIs, and the same antibody response to hepatitis B vaccination as the CF group, based on one-sided tests. Growth was normal in both groups, and no adverse events were considered to be formula-related.

CONCLUSIONS

Healthy term infants from 8 to 28 weeks of life are less likely to experience diarrhea and have higher serum immunoglobulin A concentrations with NF compared with formula without added nucleotides.

The influence of dietary nucleotides on humoral and cell immunity in the neonate and lactating infant

The organism constantly requires nucleotides, especially for tissues that present a high rate of turnover, such as the cells of the immune system. In certain circumstances, nucleotides may become semi-essential nutrients required by a particular organ. There is evidence of the potential role of exogenous nucleotides as regulators of the immune function. In experiments carried out with animals, studies have shown that dietary nucleotides stimulate the humoral immune response to T-dependent antigens and raise total antibody levels. The present study reveals an increase in the production of immunoglobulins, an improved response to vaccines, a reduction in morbidity and increased tolerance to dietary antigens. Therefore, the addition of nucleotides to formula appears to favour the immune function.

Dietary ribonucleotides modulate type 1 and type 2 T-helper cell responses against ovalbumin in young BALB/cJ mice

Dietary ribonucleotides have been shown to augment type 1 T-helper cell (Th1) responses to a protein antigen (Ag) in Th1-prone C57BL/6 mice, but their effects on type 2 Th (Th2)-prone mice are unknown. BALB/cJ mice have skewed Th2 responses against ovalbumin (OVA), characterized by augmented production of Th2 cytokines and immunoglobulin (Ig)G1/IgE antibodies (Ab); Th1 responses augment IgG2a Ab production, whereas Th2 responses augment IgG1/IgE Ab production. In this study, we determined the effects of dietary ribonucleotides obtained from yeast on the balance of Th1/Th2 responses against OVA in young BALB/cJ mice. Mice were fed a ribonucleotide-free (NF) or ribonucleotide-supplemented (NS) diet (4.74 g nucleotides/kg diet) and given OVA (10 microg/dose) with incomplete Freund's adjuvant (IFA) at 3 and 6 wk. We assessed T-cell responses in the regional draining lymph nodes (LN) by measuring production and expression of Th1/Th2 cytokines, interferon-gamma (IFN-gamma) and interleukin-5 (IL-5), respectively. Anti-OVA IgG subclass and IgE Ab levels were determined 3 wk after the first OVA challenge and 5 d and 2 wk after the second OVA challenge. Dietary ribonucleotides significantly augmented OVA-specific IFN-gamma production by the regional draining LN cells after the first and second OVA challenges. The NS diet increased anti-OVA IgG2a Ab levels after the first OVA challenge and both anti-OVA IgG2a and anti-OVA IgG2b after the second challenge. OVA-specific IgG1 and IgE Ab levels were lower (P < 0.05) after the second OVA challenge in mice fed the NS diet. Dietary ribonucleotides did not affect production or expression of IL-5. Our findings thus indicate that in Th2-prone BALB/c J mice, dietary ribonucleotides modulated skewed Th2 responses against OVA toward Th1 as measured by production of IFN-gamma, a Th1 cytokine, and changes in anti-OVA Ab isotype levels.

The metabolic effects of enterally administered ribonucleic acids

Roles for dietary sources of preformed purines and pyrimidines such as RNA in various systems have been demonstrated in recent years. These include maintenance of a competent immune system, gut development, hepatic function and many others, with a central theme of rapidly dividing cells requiring these compounds for optimal function. These compounds were previously thought to be non-essential but are now considered to be conditionally required when various stresses, including rapid growth and infection, are present. A number of recent studies are summarized that cover a variety of areas and are consistent with critical roles for dietary sources of nucleotides for many cellular functions.