Abstract  DNA microarray based transcriptome analysis has become widely used in biomedical research; however, the lack of DNA sequence information available for Chinese hamster ovary (CHO) cells has hampered the application of microarrays for this cell line widely used for recombinant therapeutic protein production. We have constructed an expressed sequence tag (EST) based CHO DNA microarray and employed it for comparative transcriptome analysis of CHO cells and mouse hybridoma cells treated with sodium butyrate. Cross-species hybridization of CHO transcripts to mouse DNA microarrays was also performed to assess the utility of cross-species microarray. The average identity among probe sequences present on both the CHO and mouse microarray was 89.6%. Although cross-species hybridization yielded non-contradicting results when compared with the same-species arrays, decreased sensitivity was observed and resulted in fewer differentially expressed genes being confidently identified. The comparatively small number of genes probed using the CHO microarray and the low number of genes identified as differentially expressed in the cross-species hybridization limited physiological interpretation of the response of CHO cells to sodium butyrate treatment. Nevertheless, when all results are combined, mouse hybridoma and CHO cells can be seen to respond similarly to butyrate treatment, affecting histone modification, chaperones, lipid metabolism, and protein processing. To further develop the utility of microarray technology in cell culture process development, an expansion of current CHO cell sequencing efforts to increase the coverage of genes on available microarrays is warranted.

Abstract  Embryonic stem cells serve as a promising technology to obtain specific cell types for a number of biomedical applications. Because traditional techniques, such as embryoid body formation result in a wide array of differentiated cells such as hepatic, neuronal, and cardiac lineages, strategies have been utilized which favor cell-specific differentiation to generate more uniformity. In the present study, we have investigated the use of sodium butyrate in a monolayer culture configuration to mediate hepatocyte differentiation of murine embryonic stem cells. Several functional assays used to characterize hepatocyte function (viz. urea secretion, intracellular albumin content, cytokeratin 18, and glycogen staining) were used to analyze the differentiating cell population, suggesting the presence of an enriched population of hepatocyte-like cells. Since mature hepatocytes mediate energy metabolism predominantly through oxidative means as opposed to hepatocyte precursors, which are primarily glycolytic, we have performed a kinetic analysis of glycolytic and functional capacity to characterize the differentiated cells. In conjunction with mitochondrial mass and activity measurements, we show that Na-butyrate-mediated differentiated cells mediate energy metabolism predominantly through glycolysis. This metabolic and mitochondrial characterization can assist in evaluating stem cell differentiation and may prove useful in identifying key regulatory molecules in mediating further differentiation.

Abstract  The antimicrobial protein cathelicidin is considered to play an important role in the defense mechanisms against bacterial infection. Recent studies show that sodium butyrate induces cathelicidin gene expression in human colonic, gastric and hepatic cells. However, little is known about the precise regulatory mechanisms underlying sodium butyrate-induced cathelicidin gene expression. In this study, we examined the regulatory mechanisms involved in sodium butyrate-induced cathelicidin gene expression using a human lung epithelial cell line, EBC-1. Our results indicate that sodium butyrate induces both cathelicidin mRNA and protein expression. Moreover, deletion or mutation of a putative activator protein-1 (AP-1) binding site in the cathelicidin gene promoter abrogated the response to sodium butyrate stimulation. Three different mitogen-activated protein (MAP) kinase inhibitors suppressed sodium butyrate-induced transactivation of the cathelicidin promoter. Electrophoretic mobility shift assays (EMSA) showed that nuclear extracts prepared from sodium butyrate-stimulated EBC-1 cells generated specific binding to probe including a putative AP-1 binding site in the cathelicidin gene promoter. Furthermore, chromatin immunoprecipitation (ChIP) assays demonstrated that sodium butyrate augmented histone acetylation of the cathelicidin promoter in EBC-1 cells. Therefore, these results indicate that AP-1 and histone acetylation of the cathelicidin promoter play a critical role in the regulation of inducible cathelicidin gene expression in EBC-1 cells stimulated with sodium butyrate.

Abstract  The human enteric flora plays a significant role in intestinal health and disease. Populations of enteric bacteria can inhibit the NF-kappa B pathway by blockade of I kappa B-alpha ubiquitination, a process catalyzed by the E3-SCF(beta-TrCP) ubiquitin ligase. The activity of this ubiquitin ligase is regulated via covalent modification of the Cullin-1 subunit by the ubiquitin-like protein NEDD8. We previously reported that interaction of viable commensal bacteria with mammalian intestinal epithelia] cells resulted in a rapid and reversible generation of reactive oxygen species (ROS) that modulated neddylation of Cullin-1 and resulted in suppressive effects on the NF-kappa B pathway. Herein, we demonstrate that butyrate and other short chain fatty acids supplemented to model human intestinal epithelia in vitro and human tissue ex vivo results in loss of neddylated Cullin-1 and show that physiological concentrations of butyrate modulate the ubiquitination and degradation of a target of the E3-SCF (beta-TrCP) ubiquitin ligase, the NF-kappa B inhibitor I kappa B-alpha. Mechanistically, we show that physiological concentrations of butyrate induces reactive oxygen species that transiently alters the intracellular redox balance and results in inactivation of the NEDD8-conjugating enzyme Ubc12 in a manner similar to effects mediated by viable bacteria. Because the normal flora produces significant amounts of butyrate and other short chain fatty acids, these data provide a functional link between a natural product of the intestinal normal flora and important epithelial inflammatory and proliferative signaling pathways. The Journal of Immunology, 2009, 182: 538- 546.

Abstract  OBJECTIVE: Sodium butyrate (butyric acid; BA) is a major metabolic by-product of the anaerobic periodontopathic bacteria present in subgingival plaque. We examined the effects of BA and/or indomethacin on cell proliferation, the expression of cyclooxygenases (COXs), prostaglandin (PG) receptors (EP1-4), extracellular matrix proteins, such as type I collagen and osteopontin, and PGE(2) production, using ROS17/2.8 cells as osteoblasts.

METHODS: The rat clonal cell line ROS 17/2.8 was cultured with 0, 10(-5), 10(-4), and 10(-3)M BA in the presence or absence of 0.5 μM indomethacin, for up to 7 days. The expression of COX-1, COX-2, EP1, EP2, EP3, EP4, type I collagen, and osteopontin was examined at the mRNA and protein levels using real-time PCR and Western blotting, respectively. The amount of PGE(2) in the culture medium was measured by ELISA.

RESULTS: Proliferation of ROS 17/2.8 cells was not affected by the addition of BA. However, PGE(2) production and the expression of COX-1 and COX-2 increased with the addition of BA. In contrast, indomethacin, an inhibitor of COX, blocked the stimulatory effect of BA. Furthermore, EP2 expression increased with BA treatment, whereas EP1 expression was not affected and the expression of EP3 and EP4 was not detected. The addition of BA also increased the expression of type I collagen and osteopontin. Indomethacin blocked about 50% of the stimulatory effect of BA on type I collagen, whereas it did not block the effect on osteopontin.

CONCLUSIONS: These results suggest that BA induces PGE(2) production by increasing the expression of COX-1 and COX-2 in osteoblasts, and that an autocrine action of the produced PGE(2), via EP1 or BA-induced EP2, is related to an increase in type I collagen expression by BA.

Abstract  BACKGROUND: Global gene expression profiles of bovine kidney epithelial cells regulated by sodium butyrate were investigated with high-density oligonucleotide microarrays. The bovine microarray with 86,191 distinct 60mer oligonucleotides, each with 4 replicates, was designed and produced with Maskless Array Synthesizer technology. These oligonucleotides represent approximately 45,383 unique cattle sequences.

RESULTS: 450 genes significantly regulated by butyrate with a median False Discovery Rate (FDR) = 0 % were identified. The majority of these genes were repressed by butyrate and associated with cell cycle control. The expression levels of 30 selected genes identified by the microarray were confirmed using real-time PCR. The results from real-time PCR positively correlated (R = 0.867) with the results from the microarray.

CONCLUSION: This study presented the genes related to multiple signal pathways such as cell cycle control and apoptosis. The profound changes in gene expression elucidate the molecular basis for the pleiotropic effects of butyrate on biological processes. These findings enable better recognition of the full range of beneficial roles butyrate may play during cattle energy metabolism, cell growth and proliferation, and possibly in fighting gastrointestinal pathogens.

Abstract  HDACs and HATs regulate histone acetylation, an epigenetic modification that controls chromatin structure and through it, gene expression. Butyrate, a dietary HDAC inhibitor, inhibits VSMC proliferation, a crucial factor in atherogenesis, and the principle mechanism in arterial and in-stent restenosis. Here, the link between antiproliferation action of butyrate and the portraits of global covalent modifications of histone H3 that it induces are characterized to understand the mechanics of butyrate-arrested VSMC proliferation. Analysis of histone H3 modifications specific to butyrate arrested VSMC proliferation display induction of histone H3-Lysine9 acetylation, inhibition of histone H3-Serine10 phosphorylation, reduction of histone H3-Lysine9 dimethylation and stimulation of histone H3-Lysine4 di-methylation, which is linked to transcriptional activation, cell cycle/mitosis, transcriptional suppression and activation, respectively. Conversely, untreated VSMCs exhibit inhibition of H3-Lysine9 acetylation, induction of H3-Serine10 phosphorylation, stimulation of H3-Lysine9 di-methylation and reduction in H3-Lysine4 di-methylation. Butyrate's cooperative effects on H3-Lysine9 acetylation and H3-Serine10 phosphorylation, and contrasting effects on di-methylation of H3-Lysine9 and H3-Lysine4 suggests that the interplay between these site-specific modifications cause distinct chromatin alterations that allow cyclin D1 and D3 induction, G1-specific cdk4, cdk6 and cdk2 downregulation, and upregulation of cdk inhibitors, p15INK4b and p21Cip1. Regardless of butyrate's effect on D-type cyclins, downregulation of G1-specific cdks and upregulation of cdk inhibitors by butyrate prevents cell cycle progression by failing to inactivate Rb. Overall, through chromatin remodeling, butyrate appears to differentially alter G1-specific cell cycle proteins to ensure proliferation arrest of VSMCs, a crucial cellular component of blood vessel wall.

Abstract  Fermentation of dietary fibres by colonic microbes leads to the production of short chain fatty acids (mainly propionate, butyrate and acetate), which are utilized by the colonic mucosa. Previous studies showed positive effects of butyrate on parameters of oxidative stress, inflammation and apoptosis. Recent studies in rats, however, showed that butyrate increased visceral sensitivity. The aim of this study was to determine the effects of physiologically relevant concentrations of butyrate on visceral perception in healthy human subjects. Eleven healthy volunteers participated in this randomized double-blind, placebo controlled cross-over study. The study consisted of three periods of 1 week each, in which the volunteers daily self-administered rectal enemas containing 100, 50 mmol L(-1) butyrate, or placebo (saline) prior to sleeping. A rectal barostat measurement was performed at the start and the end of each test period for the measurement of pain, urge and discomfort. Butyrate treatment resulted in a dose-dependent reduction of pain, urge and discomfort throughout the entire pressure range of the protocol. At a pressure of 4 mmHg, 50 and 100 mmol L(-1) butyrate concentrations resulted in a 23.9% and 42.1% reduction of pain scores, respectively, and the discomfort scores decreased by 44.2% and 69.0% respectively. At a pressure of 67 mmHg, 50 and 100 mmol L(-1) of butyrate decreased the pain scores by 23.8% and 42%, respectively, and discomfort scores 1.9% and 5.2% respectively. Colonic administration of butyrate, at physiologically relevant concentrations, dose-dependently decreases visceral sensitivity in healthy volunteers.

Abstract  Objectives: Butyrate concentrations in the gastrointestinal tract vary greatly with age. In intestinal epithelial cells, butyrate enhances gene transcription by increasing histone acetylation, rendering the nucleosome open to transcription factors. However, it inhibits human insulin-like growth factor binding protein (hIGFBP)-3 expression. We therefore hypothesized that butyrate also acts by regulating transcription factor acetylation. Methods: Gene regulation was examined in Caco-2 cells. RNA stability was measured after interruption of transcription. The activity of deletion mutations of the hIGFBP-3 promoter was examined in reporter assays. Transcription factor binding to promoter DNA was analyzed. Results: Butyrate did not increase the transcription of a repressor because it inhibited hIGFBP-3 mRNA in the absence of protein synthesis. Nor did butyrate decrease the stability of hIGFBP-3 mRNA. Analysis of the hIGFBP-3 promoter demonstrated a butyrate-response element that included the binding sites for p300 and Sp1/Sp3. Transfection of Caco-2 cells with E1A, an inhibitor of p300 acetyltransferase activity, reversed the butyrate-induced repression of hIGFBP-3. Because Sp3 represses the initiation of transcription, we studied whether butyrate induced Sp3 acetylation. Electrophoretic mobility shift assays of nuclei extracted from Caco-2 cells treated with 5 mmol/L butyrate demonstrated an extra, heavier band in addition to the Sp3-DNA binding in untreated cells. This corresponded to a protein, detected only in butyrate treated cells, that was identified both by an anti-Sp3 antibody and by an anti-acetyl lysine antibody. Conclusions: This study demonstrates that butyrate increases the acetylation of a nonhistone protein, Sp3, catalyzed by p300 acetyltransferase activity. (C) 2006 Liincott Williams & Wilkins.

Abstract  Ocular discomfort (e.g. burning, dry and itching eyes) is among top 2 symptoms in office environments. The ophthalmological explanation is aqueous-deficient dry eye and evaporative dry eye and exposure to allergens, while indoor air pollutants causing chemesthesis generally is the rationale of the indoor environmental community. Review of salient environmental, occupational, and personal risk factors, that alter the precorneal tear film (PTF), reveals at least three mechanisms resulting in ocular discomfort. First, the PTF structure is altered by a physical process that increases the emission rate of aqua loss resulting in hyperosmolarity, gland dysfunctions, and associated discomfort. Second, the structural composition of the outermost lipid layer of the PTF is altered by aggressive aerosols and combustion products, both indoors and outdoors, that facilitate loss of aqua, and possibly chemesthesis. Third, strong sensory irritating pollutants cause chemesthesis by trigeminal stimulation. In general, organic and inorganic indoor air pollutant concentrations are too low causing chemesthesis, but the odor may cause reported discomfort. The total risk of ocular discomfort is exacerbated by physical alteration of the PTF by visual tasking and climate conditions (low humidity, high temperature, and draft); further, personal factors like age, gender and use of certain medication also influence the overall stability of the PTF.

Abstract  OBJECTIVE: Decreased neutrophil apoptosis is implicated in persistent inflammation resulting in systemic inflammatory response syndrome and multiple organ dysfunctions syndromes. Short-chain fatty acids (SCFAs) may be a candidate to control neutrophil apoptosis because SCFAs are normally produced in the gut and related products have been approved for human use. We investigated the effects of SCFAs on apoptosis of activated and non-activated neutrophils and their mechanisms.

METHODS: Purified neutrophils obtained from healthy volunteers were preincubated for 1 h with or without the G-protein receptor (GPR) inhibitor pertussis toxin (100 ng/mL) or U-73122 (50 ng/mL), extracellular signal-related protein kinase inhibitor PD98059 (10 microM), mitogen-activated protein kinase (MAPK) p38 inhibitor SB203580 (25 microM), Jun kinase inhibitor-I (2 microM), caspase-3 and -7 inhibitor Z-VAD-FMK (100 microM), caspase-8 inhibitor Z-IETD-FMK (50 microM), or caspase-9 inhibitor Z-LEHD-FMK (50 microM). The cells were then cultured with or without SCFAs or trichostatin A, a typical histone deacetylase inhibitor, in the presence or absence of lipopolysaccharide (1 microg/mL) or tumor necrosis factor-alpha (100 ng/mL). Neutrophil apoptosis was assessed by annexin V staining using flow cytometry. The GPR-41 and -43 and apoptosis-related proteins (bax, mcl-1, a1) mRNA were measured by quantitative real-time polymerase chain reaction and the expression of acetylated histone H3 was determined by western blot.

RESULTS: The caspase inhibitors inhibited butyrate- and propionate-induced neutrophil apoptosis treated or untreated with lipopolysaccharide or tumor necrosis factor-alpha, whereas GPR and MAPK inhibitors had no effect. The mRNA expressions of GPR-43 and a1 protein were reduced by butyrate and propionate. The expressions of acetylated histone H3 were induced by butyrate and propionate.

CONCLUSION: These results suggest that butyrate and propionate increase apoptosis of neutrophils irrespective of their activation state, by factors other than GPRs and MAPKs, and their mechanisms likely relate to their histone deacetylase inhibition activity, which may control a1 mRNA expression.

Abstract  Previously, we reported that IFN-gamma and TNF-alpha downregulate the expression of the human Na(+)/H(+) exchanger (NHE)3 gene by modulating Sp1/Sp3 transcription factors in C2BBe1 cells. It is reported that butyrate inhibits IFN-gamma and TNF-alpha signaling pathways. In this study, we have investigated the effect of sodium butyrate (NaB) and IFN-gamma/TNF-alpha on human NHE3 promoter activity. In transient transfection studies, NaB (5 mM) led to 10-fold stimulation of NHE3 promoter activity after incubation for 24 h. With 5'-deletion analysis, the NaB-responsive region was mapped to the NHE3 core promoter, bp -95 to + 5, which we had shown previously to confer responsiveness to IFN-gamma/TNF-alpha. The stimulatory effect of NaB on the NHE3 promoter was reduced by 60% in the presence of IFN-gamma/TNF-alpha. Mutually, the repressive effect of these cytokines was attenuated by NaB. Knockdown of Sp1 and Sp3 expression with small interfering RNA (siRNA) resulted in a significant resistance to NaB effects. NaB treatment showed no effect on Sp1 and Sp3 protein expression as assessed by Western blot analyses. Gel mobility shift assays with nuclear proteins from NaB-treated cells showed enhanced binding of Sp1 and Sp3 to the NHE3 promoter. The phosphatase inhibitor okadaic acid (200 nM) blocked the stimulatory effect of NaB on the NHE3 promoter. NaB effects on the NHE3 promoter were significantly attenuated by protein phosphatase (PP)1alpha- and PP2Aalpha-specific siRNA transfection. Our data suggest that the differential regulation of NHE3 gene expression by NaB and IFN-gamma/TNF-alpha is mediated through alternative pathways that converge on Sp1/Sp3.

Abstract  Isobutanol and butanol have received attention recently as renewable resource fuel alternatives (1-3). However, toxicity is a main concern for these biofuels, with native butanol producing strains (Clostridium acetobutylicum) being unable to grow at concentrations of 1.5% vol/vol (4). The deleterious effects of alcohols have mainly been attributed to disruption of the membrane, but recent work suggests that toxicity is much more complex (5-7). To understand isobutanol and butanol toxicity we have applied an approach that integrates transcriptomic, metabolic, protein, and phenotypic data to identify networks in Escherichia coli perturbed by isobutanol and/or butanol. By the use of DNA microarray, gene knockouts, phenotypic experiments, protein and metabolic data, and bioinformatics techniques including Network Component Analysis we have characterized the isobutanol and butanol response networks of E. coli. Escherichia coli was chosen as our model organism instead Clostridium strains due to similar growth toxicity (unable to grow at concentrations of 1% vol/vol), the degree to which the transcription, metabolic, and protein-protein interaction networks of E. coli have been identified, and the potential of E. coli to be used as a host strain for biofuel production.

Abstract  The potential role of butyrate to modulate cellular metabolism through integrin receptor led to evaluation of its effect on collagen biosynthesis in cultured fibroblasts. Confluent human dermal fibroblasts were treated with 2 mM and 4 mM of sodium butyrate (NaB) for 48 h. It was found that butyrate induced collagen biosynthesis and prolidase activity independently of alpha2beta1 integrin signaling. The expressions of both alpha2 and beta1 integrin subunits as well as integrin-induced activation of focal adhesion kinase (FAK) were not affected in the cells treated with NaB. Since insulin-like growth factor-I (IGF-I) is the most potent stimulator of collagen biosynthesis in fibroblasts, the effect of butyrate on IGF-I receptor (IGF-IR) expression was evaluated. It was found that the exposure of the cells to 4 mM butyrate contributed to a distinct increase in IGF-IR. It was accompanied by a parallel increase in the expression of Sos protein and MAP-kinases (ERK1, ERK2). The data suggests that butyrate-dependent stimulation of collagen biosynthesis in cultured human skin fibroblasts undergoes through IGF-IR signaling.

Abstract  The interaction between digestive tract microbiological flora and food has an important influence on human health. Butyrate is produced during the fermentation of dietary fibres by intestinal bacteria and plays an important role in the regulation of mucosal immunity. In this report, we studied the impact of butyrate on the defence mechanism against the bacterial membrane component peptidoglycan (PGN). Butyrate was found to enhance PGN-mediated IL-8 and GRO-alpha production. The expression of these chemokines required the activation of NF-kappaB and was dependent on the concentrations of butyrate and PGN. Butyrate was found to up-regulate nucleotide-binding and oligomerisation domain (NOD) 2, but not NOD1 or TLR2. NOD2 up-regulation was mediated by an increase in histone acetylation in the Nod2 promoter region, leading to enhanced PGN-induced IL-8 and GRO-alpha secretion. Knockdown of NOD2 and TLR2 by siRNA significantly reduced PGN-mediated chemokine production, suggesting that both NOD2 and TLR2 are required for maximal response. Our findings provide a better understanding of the mechanism by which butyrate regulates mucosal immunity for normal intestinal function. Based on the results of this study, we infer that dietary fibres can impact inflammatory bowel diseases.

Abstract  The liver regenerates by progenitor cells when it is damaged in chronic liver diseases and extensive damage. The progenitor cells, also termed "oval cells" according to their morphological traits, can differentiate into hepatocytes and bile duct cells in vivo. To better understand the transcriptional pattern that accompanies the hepatic differentiation of oval cells, we applied cDNA microarray to analyze the oval cell-derived liver epithelial progenitor cells (LEPCs) during in vitro induced differentiation. Upon exposure to sodium butyrate, a histone deacetylase inhibitor, cultured LEPCs differentiate and express functional hepatocyte markers albumin, tryptophan 2, 3-dioxygenase and alcohol dehydrogenase. For expression profiling, cells were harvested at 6 h, 12 h, 1 d, 3 d and 7 d after exposure to sodium butyrate. After analyzing the microarray data by SOM clustering, total of 796 differentially regulated genes were grouped into 48 clusters. Consistent with the phenotype change of LEPCs after sodium butyrate treatment, many hepatocyte functional genes are revealed by analyzing the clusters containing genes up-regulated through all the time points. The clusters, containing down-regulated genes immediately after the induction, are also analyzed. The microarray data was validated by analyzing the expression of selected genes by quantitative real-time PCR. A set of genes expressed synergistically in these clusters may play a central role during the process of differentiation. Sodium butyrate decreases cyclin B1 and Cdk4 expression, which would be associated with LEPCs growth arrest shortly after treatment. Bmi1, a polycomb group protein, is also down-regulated immediately after treatment and remains at a low level during the induction. These findings highlight the key molecular mechanisms by which sodium butyrate, mediates its effects on cell growth arrest and induction of differentiation. In conclusion, our data reflect a global view of gene expression during hepatic differentiation of LEPCs induced by sodium butyrate.

Abstract  BACKGROUND AND AIMS: The human cathelicidin (LL-37) is one of the major antimicrobial peptides of the non-specific innate immune system in the intestinal tract. Altered expression has been associated with gastrointestinal disease. Recent studies demonstrated that butyrate induces LL-37 mRNA in colonic epithelial cells, however the underlying molecular mechanisms have not been elucidated. The objective of this study was to investigate the regulatory pathways involved in butyrate-induced up-regulation of LL-37.

METHODS AND RESULTS: Treatment of Caco-2 and HT-29 cells with butyrate led to a time-dependent up-regulation of LL-37 mRNA expression as determined by semi-quantitative RT-PCR. Up-regulation of LL-37 mRNA by butyrate was subsequently followed by an increase in LL-37 protein expression as observed by immunofluorescence. Co-incubation of butyrate with a VDR, p38 MAPK, ERK 1/2 and TGF-beta1 receptor kinase inhibitor all reduced butyrate-mediated LL-37 mRNA up-regulation. In contrast, transfection of Caco-2 cells with a dominant-negative PPARgamma mutant vector did not affect butyrate-mediated up-regulation of LL-37 mRNA.

CONCLUSION: Our results clearly demonstrate that butyrate-mediated up-regulation of LL-37 is influenced by several signalling pathways and receptors including MAPKs as well as VDR and TGF-beta1, but not by PPARgamma. These data may provide new opportunities in the treatment of gastrointestinal diseases.

Abstract  BACKGROUND: Short-chain fatty acids (SCFAs) maintain human colonic function and may help prevent colonic disease. A study with ileostomists showed that starches acylated with specific SCFAs largely survive passage through the small intestine, but the percentage released in the colon has not been established.

OBJECTIVE: The objective was to determine the percentage of ingested esterified butyrate released in the human gastrointestinal tract.

DESIGN: The study was a randomized, crossover, controlled trial consisting of baseline and four 2-wk periods during which 16 volunteers consumed diets low in resistant starch plus 20 and 40 g cooked high-amylose maize starch (HAMS: HAMS20 or HAMS40) or butyrylated HAMS (HAMSB20 or HAMSB40) daily. HAMSB20 contained 31.8 mmol esterified butyrate. Complete 48-h fecal collections were made on days 2-3 and 12-13 of each period.

RESULTS: Free fecal butyrate concentrations were higher after HAMSB40 than after HAMSB20 (P < 0.005) and HAMS (P < 0.0001) and higher than baseline data (P < 0.0001). Fecal esterified butyrate concentrations were highest in the HAMSB40 (days 12-13; P < 0.0001) group, and concentrations in the HAMSB40 (days 2-3) and HAMSB20 groups were higher than those in the HAMS groups and those at baseline (P < 0.0001). Ingestion of HAMSB20 and HAMSB40 resulted in the release of 26.8 ± 1.0 and 50.2 ± 2.4 mmol butyrate/d (days 12-13) (84.2 ± 3.0% and 79.0 ± 3.1% of total ingested esterified butyrate), respectively, in the gastrointestinal tract. By calculation, ∼57.2% of ingested esterified butyrate was released in the colon. Microbial analysis showed that this release was probably facilitated mainly by Parabacteroides distasonis, which increased in abundance with HAMSB40 (days 12-13) (P < 0.001).

CONCLUSIONS: This study shows that cooked butyrylated starch delivers esterified butyrate to the human colon effectively and has the potential to improve human bowel health. This trial is registered in the Australian Clinical Trials Registry as ACTRN012606000398505.