Branched-chain amino acid depletion conditions bone marrow for hematopoietic stem cell transplantation avoiding amino acid imbalance-associated toxicity.

Hematopoietic stem cells (HSCs) are used clinically in bone marrow (BM) transplantation due to their unique ability to reform the entire hematopoietic system. Recently, we reported that HSCs are highly sensitive to valine, one of the three branched-chain amino acids (BCAAs) in addition to isoleucine and leucine. Dietary depletion of valine could even be used as a conditioning regimen for HSC transplantation. Here, we report that HSCs are highly sensitive to the balance of BCAAs, with both proliferation and survival reduced by BCAA imbalance. However, low but balanced BCAA levels failed to rescue HSC maintenance. Importantly, in vivo depletion of all three BCAAs was significantly less toxic than depletion of valine only. We demonstrate that BCAA depletion can replace valine depletion as a safer alternative to BM conditioning. In summary, by determining HSC metabolic requirements, we can improve metabolic approaches to BM conditioning.

Prophylactic potential of defensins and L-isoleucine in tuberculosis household contacts: an experimental model.

AIM: Patients with pulmonary tuberculosis (TB) are the most important source for TB infection, being the risk of infection determined by the source case infectiousness and the contact closeness. Currently, the administration of isoniazid is used to prevent the infection to some extent in household contacts. At experimental level, defensins are efficient molecules for the treatment of TB and other infectious diseases. MATERIALS & METHODS: In this work, we used a model of Mycobacterium tuberculosis transmission by long cohabitation of infected and noninfected mice, and treated the latter group with antimicrobial peptides in order to determine the potential capacity of defensins to prevent the infection. RESULTS: Our results showed that the intratracheal administration of human neutrophil peptide-1, human ß-defensin-2 alone or in combination and the use of L-isoleucine significantly prevents bacterial transmission, diminishing pulmonary lesions and bacterial loads. CONCLUSION: Data suggest the potential use of L-isoleucine as prophylactic for TB household contacts.

L-Leucine and L-isoleucine enhance growth of BBN-induced urothelial tumors in the rat bladder by modulating expression of amino acid transporters and tumorigenesis-associated genes.

We investigated the underlying mechanisms of L-leucine and L-isoleucine mediated promotion of bladder carcinogenesis using an initiation-promotion model. Rats were administered N-butyl-N-(4-hydroxybutyl) nitrosamine for 4 weeks and then fed AIN-93G basal diet or diet supplemented with L-leucine or L-isoleucine for 8 weeks followed by the basal diet for another 8 weeks. At the end of the experiment, week 20, there was a significant elevation of papillary and nodular (PN) hyperplasia multiplicity in the amino acid groups. L-Leucine and L-isoleucine transporters were up-regulated in PN hyperplasias and/or bladder tumors compared with concomitant normal-appearing bladder urothelium at weeks 12 and/or 20 in all groups. In addition, in normal-appearing bladder urothelium, significantly increased mRNA levels of y+LAT1, LAT2, LAT4, and 4F2hc were observed in the amino acid groups compared with the BBN control group at both weeks 12 and 20, and increased mRNA levels of LAT1 were observed at week 20. Furthermore, up-regulation of TNF-α, c-fos, ß-catenin, p53, p21(Cip1/WAF1), cdk4, cyclin D1 and caspase 3 in the amino acid groups was detected in normal-appearing bladder urothelium. Overall, our results indicate that supplementation with l-leucine or l-isoleucine enhanced growth of bladder urothelial tumors by triggering expression of amino acid transporters and tumorigenesis-associated genes.

Long-term treatment with L-isoleucine or L-leucine in AIN-93G diet has promoting effects on rat bladder carcinogenesis.

In the present study, effects of L-leucine and L-isoleucine on rat bladder carcinogenesis were investigated using AIN-93G and MF basal diet. In Experiment 1, N-butyl-N-(4-hydroxybutyl)-nitrosamine was used as an initiator of bladder carcinogenesis. In the AIN-93G diet groups, a significantly higher incidence and multiplicity of bladder tumors, accompanied by decreased final body weight, was observed in the L-leucine-supplemented group and a significantly higher incidence of papillomas and total tumors was observed in the L-isoleucine-supplemented group. In the MF diet groups, the multiplicity of papillary and nodular hyperplasia was significantly increased in the L-isoleucine-supplemented group. Urinary pH values were not affected by supplementing either type of diet with L-leucine or L-isoleucine. In Experiment 2, the amino acid was administered in the basal diets for 2 weeks without initiator. No pathological lesions were observed in the bladder urothelium in any of the groups, and no significant differences in urinary pH values, microcrystals or aggregates were observed between the amino acid-supplemented groups and their respective control groups. In conclusion, long-term treatment with L-leucine or L-isoleucine has a promoting effect on rat bladder carcinogenesis; therefore, their long-term use as a dietary supplement for bladder cancer patients should be avoided until more is known.

Branched chain amino acids improve radial-arm maze acquisition and water maze forced-choice learning in rat offspring exposed in utero to hyperphenylalaninemia.

Maternal phenylketonuria results in a high incidence of children born mentally retarded. We showed that the large neutral amino acids valine, isoleucine, and leucine (VIL) ameliorate the effects of intrauterine hyperphenylalaninemia in rats on a test of complex maze learning. To further test the ameliorative effects of VIL on intrauterine CNS development during hyperphenylalaninemia, gravid rats were administered a phenylalanine/p-chlorophenylalanine (index group) supplemented diet with or without VIL added. Controls were given standard diet with or without VIL. All groups were pair-fed to the index group. As adults, the progeny exposed in utero to hyperphenylalaninemia showed characteristic learning impairments in a complex water (Cincinnati) maze on forced and elective-choice phases of the task and deficits in radial-arm maze and Morris maze acquisition, whereas those exposed to hyperphenylalaninemia combined with VIL showed no deficits in the forced-choice phase of Cincinnati maze learning and no evidence of radial-arm maze deficits. However, the improvement was not complete, with no ameliorative effects obtained on the elective-choice phase of the Cincinnati maze or on the Morris hidden platform test. No deficits were seen on phases containing test trials for memory function (Olton and Morris mazes). The acquisition differences occurred in the absence of any effects of VIL on maternal weight gain during gestation, maternal serum amino acid concentrations of phenylalanine or tyrosine, or effects on offspring growth. VIL alone produced no adverse or enhancing effects on learning or memory. Based on these data it was concluded that the VIL supplement continues to show promise as a potential treatment for intrauterinely acquired mental deficiency associated with maternal phenylketonuria.