Pharmacological Doses Of Biotin Research Articles

Targeting Sirt1, AMPK, Nrf2, CK2, and Soluble Guanylate Cyclase with Nutraceuticals: A Practical Strategy for Preserving Bone Mass.

There is a vast pre-clinical literature suggesting that certain nutraceuticals have the potential to aid the preservation of bone mass in the context of estrogen withdrawal, glucocorticoid treatment, chronic inflammation, or aging. In an effort to bring some logical clarity to these findings, the signaling pathways regulating osteoblast, osteocyte, and osteoclast induction, activity, and survival are briefly reviewed in the present study. The focus is placed on the following factors: the mechanisms that induce and activate the RUNX2 transcription factor, a key driver of osteoblast differentiation and function; the promotion of autophagy and prevention of apoptosis in osteoblasts/osteoclasts; and the induction and activation of NFATc1, which promotes the expression of many proteins required for osteoclast-mediated osteolysis. This analysis suggests that the activation of sirtuin 1 (Sirt1), AMP-activated protein kinase (AMPK), the Nrf2 transcription factor, and soluble guanylate cyclase (sGC) can be expected to aid the maintenance of bone mass, whereas the inhibition of the serine kinase CK2 should also be protective in this regard. Fortuitously, nutraceuticals are available to address each of these targets. Sirt1 activation can be promoted with ferulic acid, N1-methylnicotinamide, melatonin, nicotinamide riboside, glucosamine, and thymoquinone. Berberine, such as the drug metformin, is a clinically useful activator of AMPK. Many agents, including lipoic acid, melatonin, thymoquinone, astaxanthin, and crucifera-derived sulforaphane, can promote Nrf2 activity. Pharmacological doses of biotin can directly stimulate sGC. Additionally, certain flavonols, notably quercetin, can inhibit CK2 in high nanomolar concentrations that may be clinically relevant. Many, though not all, of these agents have shown favorable effects on bone density and structure in rodent models of bone loss. Complex nutraceutical regimens providing a selection of these nutraceuticals in clinically meaningful doses may have an important potential for preserving bone health. Concurrent supplementation with taurine, N-acetylcysteine, vitamins D and K2, and minerals, including magnesium, zinc, and manganese, plus a diet naturally high in potassium, may also be helpful in this regard.

Holocarboxylase synthetase knockout is embryonic lethal in mice.

Holocarboxylase synthetase (HLCS) catalyzes the biotinylation of five distinct biotin-dependent carboxylases and perhaps chromatin proteins. HLCS deficiency causes multiple carboxylase deficiency which results in fatal consequences unless patients are diagnosed early and treated with pharmacological doses of biotin. The objective of this study was to develop an HLCS conditional knockout (KO) mouse and assess effects of HLCS knockout on embryo survival. In the mouse, exon 8 is flanked by LoxP sites, thereby removing a catalytically important region upon recombination by Cre. HLCS conditional KO mice were backcrossed for 14 generations with C57BL/6J mice to yield Hlcstm1Jze. Fertility and weight gain were normal and no frank disease phenotypes and abnormal feeding behavior were observed in the absence of Cre. HLCS knockout was embryonic lethal when dams homozygous for both the floxed Hlcs gene and tamoxifen-inducible Cre recombinase (denoted Hlcstm1.1Jze) were injected with tamoxifen on gestational days 2.5 and 10.5. This is the first report of an HLCS conditional KO mouse, which enables studies of the roles of HLCS and biotin in intermediary metabolism.

Recovery of enzyme activity in biotinidase deficient individuals during early childhood.

Deficiency of the biotinidase (BTD) enzyme is an inborn error of biotin metabolism caused by biallelic pathogenic variants in the BTD gene. There are two forms, partial and profound BTD deficiency, which both can be successfully treated with pharmacological doses of biotin, justifying the inclusion of this disorder in the newborn screening in numerous countries. We investigated the BTD deficiency cohort (N = 87) in our metabolic center, as it was detected upon newborn screening since 2005, and aimed to better understand the long‐term course of BTD enzyme activity and how it may relate to the patients' genetic background. We observed that individuals with partial BTD deficiency display an elevation of BTD enzyme activity with increasing age in 48% of cases—a recovery which allowed adjustment or stop of biotin supplementation in 20% of all individuals. In addition, we were able to recruit 56 patients (64%) for genetic testing, revealing 19 different variants (2 novel), and constituting 22 different genotypes. Genotype–phenotype correlations revealed that the most abundant allele in our cohort p.(Asp444His) was also the most common variant in patients displaying recovery of BTD enzyme activity. Based on our results, we recommend to retest all patients with partial BTD deficiency at the age of 5 years, as this may result in an impact on therapy. Moreover, genetic testing of BTD deficient individuals can allow prediction of the severity of BTD deficiency and of the likelihood of BTD enzyme activity recovery with age.

Novel mutations causing biotinidase deficiency in individuals identified by the newborn screening program in Minas Gerais, Brazil.

Biotinidase deficiency is an autosomal recessive inherited metabolic disorder caused by mutations in the BTD gene. Clinical manifestations can be treated and effectively prevented with pharmacological doses of biotin. Nine novel mutations in BTD are reported in 14 children diagnosed by the newborn screening program in Minas Gerais, Brazil, from June 2013 to December 2017. Serum BTD enzyme activity was determined for all cases and some parents. Two of the mutations are deletions and seven missense mutations located in the exonic region of the BTD gene, mostly in exon 4. Two newborns were profoundly biotinidase-deficient (one homozygous p.A534V [c.1601C > T] and another, double heterozygous for a novel mutation p.R211S [c.631C > A] co-inherited with an already described mutation p.T532 M [c.1595C > T]). Two mutations were associated with a partial deficiency of biotinidase (p.F361 V [c.1081 T > G] in two homozygous children, and p.S311 T [c.932G > C] in a compound heterozygous child who co-inherited a known severe mutation p.Y438X [c.1314 T > A]). The remaining five mutations were found in compound heterozygous children. Hence, a definitive conclusion about the degree of biotinidase deficiency is not possible yet. These results emphasize the importance of sequencing the BTD gene as an important tool to gain a better understanding of the correlation between biochemical phenotype and genotype.

Diagnostics and treatment the deficiency of biotinidase in practice of the children’s neurologist

Biotinidase deficiency is a hereditary metabolic disease from the group of organic acidurias with an autosomal recessive type of inheritance. The disease is caused by mutations in the BTD gene, which encodes an enzyme biotinidase. Deficiency of biotinidase leads to insufficiency of intracellular Biotin, which is the coenzyme of four carboxylases involved in gluconeogenesis, leucine metabolism and biosynthesis of fatty acids. At infringement of function of carboxylase accumulate substrates that are toxic to the human body. Deficiency of biotinidase is manifested primarily by neurocutaneous disorders. The Central nervous system is particularly vulnerable, since the activity of biotinidase in the human brain is very low and therefore, for the normal functioning of neurons, it is necessary to receive enough biotin through the blood-brain barrier. With its deficiency, neurological disorders for a certain period may be the only sign of the disease. Symptoms can be successfully cured or prevented by the introduction of pharmacological doses of biotin. The article presents two clinical observations of young children with biotinidase deficiency, the main manifestation of which in the first clinical case were neurological disorders, in the second – respiratory disorders. To confirm the diagnosis, an enzyme diagnosis was carried out, which revealed a low level of biotinidase. The rapid and pronounced efficacy of biotin therapy with cessation of attacks, the possibility of cancellation of anticonvulsants, regression of neurological, skin and respiratory disorders.

Modulation of the Rat Hepatic Cytochrome P4501A Subfamily Using Biotin Supplementation

Studies have found that biotin favors glucose and lipid metabolism, and medications containing biotin have been developed. Despite the use of biotin as a pharmacological agent, few studies have addressed toxicity aspects including the possible interaction with cytochrome P450 enzyme family. This study analyzed the effects of pharmacological doses of biotin on the expression and activity of the cytochrome P4501A subfamily involved in the metabolism of xenobiotics. Wistar rats were treated daily with biotin (2 mg/kg, i.p.), while the control groups were treated with saline. All of the rats were sacrificed by cervical dislocation after 1, 3, 5, or 7 days of treatment. CYP1A1 and CYP1A2 mRNAs were modified by biotin while enzyme activity and protein concentration were not affected. The lack of an effect of biotin on CYP1A activity was confirmed using other experimental strategies, including (i) cotreatment of the animals with biotin and a known CYP1A inducer; (ii) the addition of biotin to the reaction mixtures for the measurement of CYP1A1 and CYP1A2 activities; and (iii) the use of an S9 mixture that was prepared from control and biotin-treated rats to analyze the activation of benzo[a]pyrene (BaP) into mutagenic metabolites using the Ames test. The results suggest that biotin does not influence the CYP1A-mediated metabolism of xenobiotics.

Hallazgos clínicos y genéticos en pacientes con deficiencia de biotinidasa detectados en el cribado neonatal o selectivo de sordera o de enfermedades metabólicas hereditarias

Background and objetive To evaluate clinical, biochemical and genetic findings of two series of patients with biotinidase deficiency. Patients and method Fifteen cases detected through newborn screening and six through selective screening for hearing loss or metabolic disease. Results No patient detected by neonatal screening had symptoms and only one case with partial biotinidase activity developed myoclonic seizures that resolved with biotin. More common mutations found among this group were p.D444H and the double mutation [p.D444H;p.A171T]. However, neurological and hearing manifestations predominated among the six symptomatic cases and mutations p.L32fs, p.G34fs, p.T401I, p.D444H, p.T532 M and the novel one p.L466fs were identified. Patients with profound biotinidase deficiency and/or clinical signs were treated with pharmacological doses of biotin (10-30 mg daily). Conclusion Biotinidase deficiency must be included in the newborn screening programmes in order to begin early treatment even in partial forms. Different mutations found in both series of patients suggest that routine genetic procedure of the BTD gene by direct sequencing might be useful to assign patients to the partial or profound form of the disease.

Pharmacological effects of biotin

In the last few decades, more vitamin-mediated effects have been discovered at the level of gene expression. Increasing knowledge on the molecular mechanisms of these vitamins has opened new perspectives that form a connection between nutritional signals and the development of new therapeutic agents. Besides its role as a carboxylase prosthetic group, biotin regulates gene expression and has a wide repertoire of effects on systemic processes. The vitamin regulates genes that are critical in the regulation of intermediary metabolism: Biotin has stimulatory effects on genes whose action favors hypoglycemia (insulin, insulin receptor, pancreatic and hepatic glucokinase); on the contrary, biotin decreases the expression of hepatic phosphoenolpyruvate carboxykinase, a key gluconeogenic enzyme that stimulates glucose production by the liver. The findings that biotin regulates the expression of genes that are critical in the regulation of intermediary metabolism are in agreement with several observations that indicate that biotin supply is involved in glucose and lipid homeostasis. Biotin deficiency has been linked to impaired glucose tolerance and decreased utilization of glucose. On the other hand, the diabetic state appears to be ameliorated by pharmacological doses of biotin. Likewise, pharmacological doses of biotin appear to decrease plasma lipid concentrations and modify lipid metabolism. The effects of biotin on carbohydrate metabolism and the lack of toxic effects of the vitamin at pharmacological doses suggest that biotin could be used in the development of new therapeutics in the treatment of hyperglycemia and hyperlipidemia, an area that we are actively investigating.

Biotin supplementation decreases the expression of the SERCA3 gene ( ATP2A3) in Jurkat cells, thus, triggering unfolded protein response

Protein folding in the endoplasmic reticulum (ER) depends on Ca 2+; uptake of Ca 2+ into the ER is mediated by sarco/endoplasmic reticulum Ca 2+-ATPase 3 (SERCA3). The 5′-flanking region of the SERCA3 gene ( ATP2A3) contains numerous binding sites for the transcription factors Sp1 and Sp3. Biotin affects the nuclear abundance of Sp1 and Sp3, which may act as transcriptional activators or repressors. Here we determined whether biotin affects the expression of the SERCA3 gene and, thus, protein folding in human lymphoid cells. Jurkat cells were cultured in media containing 0.025 nmol/L biotin (denoted “deficient”) or 10 nmol/L biotin (“supplemented”). The transcriptional activity of the full-length human SERCA3 promoter was 50% lower in biotin-supplemented cells compared to biotin-deficient cells. Biotin-dependent repressors bind to elements located 731–1312 bp upstream from the transcription start site in the SERCA3 gene. The following suggest that low expression of SERCA3 in biotin-supplemented cells impaired folding of secretory proteins in the ER, triggering unfolded protein response: (i) sequestration of Ca 2+ in the ER decreased by 14–24% in response to biotin supplementation; (ii) secretion of interleukin-2 into the extracellular space decreased by 75% in response to biotin supplementation; (iii) the nuclear abundance of stress-induced transcription factors increased in response to biotin supplementation; and (iv) the abundance of stress-related proteins such ubiquitin activating enzyme 1, growth arrest and DNA damage 153 gene, X-box binding protein 1 and phosphorylated eukaryotic translation initiation factor 2α increased in response to biotin supplementation. Collectively, this study suggests that supplements containing pharmacological doses of biotin may cause cell stress by impairing protein folding in the ER.

Identification and characterization of mutations in patients with holocarboxylase synthetase deficiency.

Holocarboxylase synthetase deficiency (HCS) is an autosomal recessive disorder characterized by metabolic ketoacidosis, abnormal urine organic metabolites, and dermatitis. These symptoms are improved by pharmacological doses of biotin. In this study, we have analyzed seven patients with HCS deficiency found in European and Middle Eastern countries by using reverse transcription/polymerase chain reaction/single-stranded conformation polymorphism and a sequencing analysis. Although we had previously reported that two mutations were frequent in Japanese patients, no frequent mutations were found in the patients analyzed in this study. Seven novel mutations were identified in the cDNA of the patients; these included three missense mutations, two single-base deletions that resulted in a termination codon, a three-base in-frame deletion, and a 68-bp deletion. A new polymorphism C1121T was also identified in four alleles. A transient expression study demonstrated that the HCS activities of three missense mutations and one amino acid deletion were 1%-14% that of wild-type cDNA; in contrast, the activities of the two single-base deletions followed by a termination codon and Asp571Asn were nearly undetectable. These data suggest that a variety of mutations is responsible for decreasing HCS activity and that the aspartate residue at amino acid position 571 may be crucial for the catalytic activity of HCS.

Bioavailability of biotin given orally to humans in pharmacologic doses

Patients with carboxylase deficiency are treated with pharmacologic doses of biotin. We sought to determine the bioavailability of biotin at pharmacologic doses. Biotin was administered orally (2.1, 8.2, or 81.9 micromol) or intravenously (18.4 micromol) to 6 healthy adults in a crossover design with > or =2 wk between each biotin administration. Before and after each administration, timed 24-h urine samples were collected. Urinary biotin and biotin metabolites were analyzed by an HPLC avidin-binding assay. Urinary recoveries of biotin plus metabolites were similar (approximately 50%) after the 2 largest oral doses and the 1 intravenous dose, suggesting 100% bioavailability of the 2 largest oral doses. For unexplained reasons, the apparent recovery of the smallest oral dose was about twice that of the other doses. For all 4 doses, biotin accounted for >50% of the total of biotin and biotin metabolites in urine. Bisnorbiotin (13-23%), biotin-d,l-sulfoxide (5-13%), bisnorbiotin methyl ketone (3-9%), and biotin sulfone (1-3%) accounted for the remainder. The percentage excretion of biotin was greater when biotin was administered intravenously and for the largest oral dose than for the 2 smallest oral doses. Our data provide evidence that oral biotin is completely absorbed even when pharmacologic doses are administered. Biotin metabolites account for a substantial portion of total urinary excretion and must be considered in bioavailability studies. We speculate that renal losses of biotin (as a percentage of the dose administered) are moderately elevated when pharmacologic doses of biotin are administered.

Double mutation (A171T and D444H) is a common cause of profound biotinidase deficiency in children ascertained by newborn screening the the United States. Mutations in brief no. 128. Online.

Biotinidase deficiency is inherited as an antosomal recessive trait that, unless treated with pharmacologic doses of biotin, can result in neurologic and cutaneous symptoms. We have identified two new mutations in exon D of the biotinidase gene of children with profound biotinidase deficiency ascertained by newborn screening. Transition 511G->A near the 5' end of exon D results in a substitution of threonine for alanine 171 (A171T) and transversion 1330G->C occurs close to the 3' end of exon D causing a substitution of histidine for aspartic acid 444 (D444H). The D444H mutation was detected in four individuals from our normal population whose mean serum biotinidase activity is 5.25 nmol/min/ml, which is significantly lower than the mean normal activity (7.1 nmol/min/ml). We calculated that this mutation causes a 52% loss of activity in the aberrant enzyme. Twenty-three individuals with the D444H mutation were found by allele specific oligonucleotide analysis of DNA from 296 randomly-selected, anonymous dried-blood spots. We estimate the frequency of this allele in the general population to be 0.039. In contrast, no individuals in 376 have the A171T mutation. Fourteen children (eleven probands and three siblings) out of the 31 enzyme-deficient children have both the A171T and D444H mutations. Both mutations are inherited from a single parent as a double mutation allele. The nine families in which this allele was identified are of mostly European ancestry, although the mutation cannot be attributed to a specific nationality or ethnic group. The serum of a child who is homozygous for the double mutation allele has very little CRM and the aberrant enzyme has very low biotinylhydrolase activity and no botinyl-transferase activity. This double mutation allele (A171T and D444H) is a common cause of profound biotinidase deficience in children ascertained by newborn screening in the United States.

Proliferation and differentiation of cultured human follicular keratinocytes are not influenced by biotin.

In humans and in animals, biotin deficiency causes pathological changes in the skin and its appendages. High doses of biotin may also have beneficial effects on skin, hair and fingernails in humans and animals with normal biotin status. Therefore, we investigated the effects of low and high concentrations of biotin on proliferation and differentiation of cultured outer root sheath cells from human hair follicles as an in vitro model for skin. The activities of biotin-dependent carboxylases were measured to evaluate the biotin status of the cells. In monolayer cultures of outer root sheath cells, proliferation and expression of the differentiation-specific keratins K1 and K10 were not influenced by extremely low concentrations of biotin (<2 x 10(-10) mol/l) or by pharmacological doses of biotin (10(-5) mol/l). Biotin deficiency of the cells was confirmed under the former condition by demonstrating decreased activities of the mitochondrial carboxylases. In organotypic cocultures of outer root sheath cells and dermal fibroblasts, in which stratified epithelia resembling epidermis were developed, the biotin concentration had no effect on the expression of all tested epidermal differentiation markers, including the suprabasal keratins K1 and K10, the hyperproliferation-associated keratin K16, involucrin and filaggrin.

Regulation of intestinal biotin transport in the rat: effect of biotin deficiency and supplementation.

The effect of biotin deficiency and supplementation at pharmacological doses on the intestinal transport of the vitamin was examined in the rat using a brush-border membrane vesicle (BBMV) technique. Transport of biotin in both jejunal and ileal BBMV was significantly (P less than 0.05-0.01) higher in biotin-deficient rats compared with control (pair-fed) rats. This increase in biotin transport appeared to be specific because transport of D-glucose was similar in the two rat groups. The increase in biotin transport in the deficient rats appeared to be mediated through a marked increase (146-230%) in the Vmax of the biotin transport process (with minimal change in the apparent Km), suggesting an increase in the number of the transport carriers. In contrast, supplementation at pharmacological doses of biotin caused significant (P less than 0.05-0.01) and specific decrease (suppression) in biotin transport compared with (unsupplemented) controls. The suppression of biotin transport in the supplemented rats appeared to be mediated through a marked decrease (58%) in the Vmax of the biotin transport process (with minimal change in the apparent Km), suggesting a decrease in the number of the transport carriers. These results provide evidence that biotin transport in the intestine is regulated by the level of the vitamin in the diet (and/or body stores). Furthermore, the results demonstrate the ability of the small intestine to adapt to the challenge of deficiency of an essential nutrient, a capability that may be crucial for the survival of the animal.

Effect of biotin deficiency and supplementation on lipid metabolism in rats: cholesterol and lipoproteins

The effect of biotin deficiency and supplementation upon tissue cholesterol and serum lipoprotein profile in rats was investigated. Biotin-dependent carboxylases in liver of deficient animals were decreased to 12–27% of control activity. The brain carboxylase activities of deficient rats were reduced less than in liver. The total, free, and esterified cholesterol were decreased in the serum of deficient rats compared to those in control or supplemented rats. Deficient rats had increased serum low-density lipoprotein fractions and decreased very low-density lipoprotein fractions, but no change in the high-density lipoprotein fractions. No differences were found between groups in the cholesterol content of liver, cerebrum, or cerebellum. Pharmacologic doses of biotin had no effect on tissue cholesterol content or serum lipoprotein profile. These results suggest that the neurologic symptoms in biotin deficiency and in the inherited multiple carboxylase deficiencies are not due to alterations in the content of cholesterol or lipoproteins.

LACTIC ACIDOSIS DUE TO A DEFECT IN PYRUVATE METABOLISM IN 3 SIBLINGS

3 infants are reported who were born to related North American Indian parents. Each infant developed metabolic acidosis and fasting hypoglycemia shortly after birth. Blood lactate and pyruvate were greatly increased in all infants and, in siblings 2 and 3, there was marked elevation of plasma alanine, proline and glutamic acid. Alanine and proline were also elevated in spinal fluid. Urinary pyruvate and α-ketoglutarate were increased. The following causes of organic acidosis were excluded: liver glycogen disease, fructose diphosphatase deficiency, methylmalonic acidemia, propionic acidemia, isovaleric acidemia, butyric and caproic acid disease and β-methylcrotonylglycinuria. After infusion of U-14 C alanine into one infant, the label was measured in glucose, lactate and expired CO2 in approximately normal adult proportions, suygesting that gluconeogenesis pathways were intact. Normal activity of phosphoenolpyruvate carboxykinase was measured in fibroblasts. The biochemical abnormalities were not influenced by pharmacological doses of biotin, thiamine or prednisone. Siblings 1 and 2 died at 4 months of age. It is postulated that these siblinas had an inherited defect in pyruvate metabolism, possibly at the level of the pyruvate dehydrogenase complex.

Biochemical studies and therapy in subacute necrotizing encephalomyelopathy (Leigh's syndrome)

The clinical course, biochemical abnormalities, and the effects of vitamin therapy in subacute necrotizing encephalomyelopathy are described in a patient who was serially evaluated from birth. Important features include increased cerebrospinal protein, elevated blood lactic acid values, and abnormal macular morphology detected when the patient was asymptomatic. Renal tubular acidosis and alaninemia were noted shortly after the onset of symptoms. No clinical improvement was noted with pharmacologic doses of biotin, thiamine (hydrochloride or propyldisulfide), or lipoic acid. Hepatic pyruvate carboxylase was within the range of control values early in the disease but was negligible in postmortem material. The clinical and biochemical course suggests that low levels of hepatic pyruvate carboxylase in postmortem material were secondary effects of an otherwise as yet unknown biochemical process. Decreased cerebral pyruvate carboxylase activity at autopsy was documented for the first time.