In vitro glycation of human serum albumin by dihydroxyacetone and dihydroxyacetone phosphate

Dihydroxyacetone phosphate accumulation leads to podocyte pyroptosis in diabetic kidney disease

Diabetic kidney disease (DKD) can lead to accumulation of glucose upstream metabolites due to dysfunctional glycolysis. But the effects of accumulated glycolysis metabolites on podocytes in DKD remain unknown. The present study examined the effect of dihydroxyacetone phosphate (DHAP) on high glucose induced podocyte pyroptosis. By metabolomics, levels of DHAP, GAP, glucose-6-phosphate and fructose 1, 6-bisphosphate were significantly increased in glomeruli of db/db mice. Furthermore, the expression of LDHA and PKM2 were decreased. mRNA sequencing showed upregulation of pyroptosis-related genes (Nlrp3, Casp1, etc.). Targeted metabolomics demonstrated higher level of DHAP in HG-treated podocytes. In vitro, ALDOB expression in HG-treated podocytes was significantly increased. siALDOB-transfected podocytes showed less DHAP level, mTORC1 activation, reactive oxygen species (ROS) production, and pyroptosis, while overexpression of ALDOB had opposite effects. Furthermore, GAP had no effect on mTORC1 activation, and mTORC1 inhibitor rapamycin alleviated ROS production and pyroptosis in HG-stimulated podocytes. Our findings demonstrate that DHAP represents a critical metabolic product for pyroptosis in HG-stimulated podocytes through regulation of mTORC1 pathway. In addition, the results provide evidence that podocyte injury in DKD may be treated by reducing DHAP.

Correlation between acute brain injury and brain metabonomics in dichlorvos-poisoned broilers

Dichlorvos (DDVP) is an insecticide with neurotoxicity that is widely used in agricultural production and life. However, the effects of acute DDVP poisoning on brain tissue remain underinvestigated. The purpose of this study was to evaluate the differences within 15 min-6 h in plasma biochemical indexes, brain histology and metabolites among three groups of commercial broilers orally administered different dosages of DDVP one time: (1) high-dose group (11.3 mg/kg), (2) low-dose group (2.48 mg/kg) and (3) control group (0 mg/kg). The results of biochemical indexes showed that acute DDVP poisoning could cause hyperglycemia and oxidative stress in poisoned broilers. Histological examination showed that DDVP could induce brain edema, abnormal expression of glial fibrillary acidic protein (GFAP) and neuronal mitochondrial damage in broilers. Whole-brain metabolism showed that DDVP could significantly change the secretion of neurotransmitters, energy metabolism, amino acid metabolism and nucleotide metabolism. Correlation analysis showed that metabolites such as hypoxanthine, acetylcarnitine and glucose 6-phosphate were significantly correlated with blood glucose, biomarkers of oxidative stress and brain injury pathology. The results of this study provide new insights into the molecular mechanism of brain tissue responses to acute DDVP exposure in broilers and deliver important information for clinical research on neurodegenerative diseases caused by acute DDVP poisoning.

Exogenous exposure to dihydroxyacetone mimics high fructose induced oxidative stress and mitochondrial dysfunction

Dihydroxyacetone (DHA) is a three-carbon sugar that is the active ingredient in sunless tanning products and a by-product of electronic cigarette (e-cigarette) combustion. Increased use of sunless tanning products and e-cigarettes has elevated exposures to DHA through inhalation and absorption. Studies have confirmed that DHA is rapidly absorbed into cells and can enter into metabolic pathways following phosphorylation to dihydroxyacetone phosphate (DHAP), a product of fructose metabolism. Recent reports have suggested metabolic imbalance and cellular stress results from DHA exposures. However, the impact of elevated exposure to DHA on human health is currently under-investigated. We propose that exogenous exposures to DHA increase DHAP levels in cells and mimic fructose exposures to produce oxidative stress, mitochondrial dysfunction, and gene and protein expression changes. Here, we review cell line and animal model exposures to fructose to highlight similarities in the effects produced by exogenous exposures to DHA. Given the long-term health consequences of fructose exposure, this review emphasizes the pressing need to further examine DHA exposures from sunless tanning products and e-cigarettes.

Autosomal recessive hypotrichosis with loose anagen hairs associated with TKFC mutations

BACKGROUND

Loose anagen hair is a rare form of impaired hair anchorage in which anagen hairs that lack inner and outer root sheaths can be gently and painlessly plucked from the scalp. This condition usually occurs in children and is often self-limiting. A genetic basis for the disorder has been suggested but not proven. A better understanding the aetiology of loose anagen hair may improve prevention and treatment strategies.

OBJECTIVES

To identify a possible genetic basis of loose anagen hair using next-generation DNA sequencing and functional analysis of variants identified.

METHODS

In this case study, whole-exome sequencing analysis of a pedigree with one affected individual with features of loose anagen hair was performed.

RESULTS

The patient was found to be compound heterozygous for two single-nucleotide substitutions in TKFC resulting in the following missense mutations: c.574G> C (p.Gly192Arg) and c.682C> T (p.Arg228Trp). Structural analysis of human TKFC showed that both mutations are located near the active site cavity. Kinetic assays of recombinant proteins bearing either of these amino acid substitutions showed almost no dihydroxyacetone kinase or D-glyceraldehyde kinase activity, and FMN cyclase activity reduced to just 10% of wildtype catalytic activity.

CONCLUSIONS

TKFC missense mutations may predispose to the development of loose anagen hairs. Identification of this new biochemical pathobiology expands the metabolic and genetic basis of hypotrichosis.

The sunless tanning agent dihydroxyacetone induces stress response gene expression and signaling in cultured human keratinocytes and reconstructed epidermis

Sunless (chemical) tanning is widely regarded as a safe alternative to solar UV-induced skin tanning known to be associated with epidermal genotoxic stress, but the cutaneous biology impacted by chemical tanning remains largely unexplored. Chemical tanning is based on the formation of melanin-mimetic cutaneous pigments ('melanoidins') from spontaneous amino-carbonyl ('glycation') reactions between epidermal amino acid/protein components and reactive sugars including the glycolytic ketose dihydroxyacetone (DHA). Here, we have examined the cutaneous effects of acute DHA-exposure on cultured human HaCaT keratinocytes and epidermal reconstructs, profiled by gene expression array analysis and immunodetection. In keratinocytes, DHA-exposure performed at low millimolar concentrations did not impair viability while causing a pronounced cellular stress response as obvious from rapid activation of phospho-protein signal transduction [p-p38, p-Hsp27(S15/S78), p-eIF2α] and gene expression changes (HSPA6, HMOX1, CRYAB, CCL3), not observable upon exposure to the non-ketose, tanning-inactive DHA-control glycerol. Formation of advanced glycation end products (AGEs) from posttranslational protein-adduction was confirmed by quantitative mass spectrometric detection of N-ε-(carboxyethyl)-l-lysine (CEL) and N7-carboxyethyl-l-arginine, and skin cells with CRISPR-Cas9-based elimination of the carbonyl stress response gene GLO1 (encoding glyoxalase 1) displayed hypersensitivity to DHA-cytotoxicity. In human epidermal reconstructs a topical use-relevant DHA-dose regimen elicited a comparable stress response as revealed by gene expression array (HSPA1A, HSPA6, HSPD1, IL6, DDIT3, EGR1) and immunohistochemical analysis (CEL, HO-1, p-Hsp27-S78). In DHA-treated SKH-1 hairless mouse skin IHC-detection revealed epidermal occurrence of CEL- and p-Hsp27-epitopes. For comparison, stress response gene expression array analysis was performed in epidermis exposed to a supra-erythemal dose of solar simulated UV (2 MEDs), identifying genes equally or differentially sensitive to either one of these cutaneous stimuli [DHA ('sunless tanning') versus solar UV ('sun-induced tanning')]. Given the worldwide use of chemical tanners in consumer products, these prototype data documenting a DHA-induced specific cutaneous stress response deserve further molecular exploration in living human skin.

Dihydroxyacetone Exposure Alters NAD(P)H and Induces Mitochondrial Stress and Autophagy in HEK293T Cells

Dihydroxyacetone phosphate (DHAP) is the endogenous byproduct of fructose metabolism. Excess DHAP in cells can induce advanced glycation end products and oxidative stress. Dihydroxyacetone (DHA) is the triose precursor to DHAP. DHA is used as the active ingredient in sunless tanning products, including aerosolized spray tans, and is formed by the combustion of solvents found in electronic cigarettes. Human exposure to DHA has been increasing as the popularity of sunless tanning products and electronic cigarettes has grown. Topically applied DHA is absorbed through the viable layers of the skin and into the bloodstream. Exogenous exposure to DHA is cytotoxic in immortalized keratinocytes and melanoma cells with cell cycle arrest induced within 24 h and cell death occurring by apoptosis at consumer-relevant concentrations of DHA within 72 h. Less is known about systemic exposures to DHA that occur following absorption through skin, and now through inhalation of the aerosolized DHA used in spray tanning. In the present study, HEK293T cells were exposed to consumer-relevant concentrations of DHA to examine the cytotoxicity of systemic exposures. HEK293T cells were sensitive to consumer-relevant doses of DHA with an IC₅₀ value of 2.4 ± 0.3 mM. However, cell cycle arrest did not begin until 48 h after DHA exposure. DHA-exposed cells showed altered metabolic activity with decreased mitochondrial function and decreased lactate and ATP production observed within 24 h of exposure. Autofluorescent imaging and NAD⁺ sensors also revealed an imbalance in the redox cofactors NAD⁺/NADH within 24 h of exposure. Cell death occurred by autophagy indicated by increases in LC3B and SIRT1. Despite DHA's ability to be converted to DHAP and integrated into metabolic pathways, the metabolic dysfunction and starvation responses observed in the HEK293T cells indicate that DHA does not readily contribute to the energetic pool in these cells.

Antiglycation and antioxidant activity of four Iranian medical plant extracts

Objective

Diabetes mellitus (DM) is the most common metabolic disorder that defined by chronic hyperglycemia for the deficiency in insulin secretion or resistance. Hyperglycemia could induce non-enzymatic glycation of proteins. It has been suggested that some traditional plants can improve blood glucose and inhibit glycation process. This work evaluates and compares the anti-glycation activities of four Iranian plant extracts in vitro.

Methods

The methanolic extract of “Fumaria officinalis, Stachys lavandulifolia, Salvia hydrangea and Rosa Damascene” was prepared in three different concentrations. Phenolic, flavonoids content and antioxidant activity were evaluated. The multistage glycation markers-fructosamines (early stage), protein carbonyls (intermediate stage) and β aggregation of albumin were investigated in the bovine serum albumin (BSA)/ glucose systemt.

Results

All plants showed the high potency of scavenging free radicals and glycation inhibition in the following order: Fumaria officinalis> Rosa Damascene> Stachys lavandulifolia > Salvia hydrangea. There was a significant correlation between antioxidant and anti-glycation activity. Also, the antioxidant and anti-glycation capacity of extracts correlated with total phenolic and flavonoids content.

Conclusion

Our findings demonstrated that the studied plants are good sources of anti-glycation and antioxidant compounds and, these properties can primarily attributable to phenolics, particularly flavonoids.

Efficacy and Safety of a Multistrain Probiotic Formulation Depends from Manufacturing

Background

Variability in probiotics manufacturing may affect their properties, with potential implications for their efficacy and safety. This is of particular concern with probiotic products destined for use in patients with serious medical conditions, including human immunodeficiency virus (HIV) infection. The purpose of the study was to carry out a series of experiments comparing the properties of the US-made probiotic formulation originally commercialized under the brand name VSL#3^®, with those of the Italian-made formulation now commercialized under the same name. The US-made formulation has previously shown beneficial effects at the intestinal and neurological levels in HIV-infected subjects as well as in patients with inflammatory bowel diseases and hepatic encephalopathy.

Methods

Eleven subjects receiving combined antiretroviral therapy for HIV-1 were treated for 6 months with the US-made VSL#3 formulation. At baseline and 6 months, T-cells were analyzed for phenotype and activation markers, and fecal samples were analyzed for bifidobacteria, lactobacilli, and their metabolites. The fecal metabolome was assessed using ¹H-NMR spectroscopy. Production of metabolites of interest by bacteria obtained from sachets of the two formulations was compared in vitro and their effects on a rat intestinal epithelial cell line (IEC-6) were assessed. Particular attention was paid to the metabolite 1,3-dihydroxyacetone (DHA).

Results

At 6 months, fecal samples showed a significant increase in the specific bacterial genera contained in the probiotic supplement. Immune activation was reduced as shown by a significant reduction in the percentage of CD4⁺CD38⁺HLA-DR⁺ T-cells at 6 months. Fecal concentrations of DHA decreased significantly. In vitro, significant differences in the production and metabolism of DHA were found between bacteria from the US-made and Italian-made formulations: the US-made formulation was able to metabolize DHA whereas the bacteria in the Italian-made formulation were producing DHA. DHA reduced the viability of Streptococcus thermophilus, reduced IEC-6 cell viability in a dose-dependent manner, and also led to a lower rate of repair to scratched IEC-6 cell monolayer.

Conclusion

Our data, in conjunction with previously published findings, confirm that the new Italian-made formulation of VSL#3^® is different from the previous US-made VSL#3 and therefore its efficacy and safety in HIV-infected subjects is still unproven.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2011-2012

This review is the seventh update of the original article published in 1999 on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2012. General aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, and fragmentation are covered in the first part of the review and applications to various structural types constitute the remainder. The main groups of compound are oligo- and poly-saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Much of this material is presented in tabular form. Also discussed are medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. © 2015 Wiley Periodicals, Inc. Mass Spec Rev 36:255-422, 2017.

Effect of Simultaneous Administration of Dihydroxyacetone on the Diffusion of Lawsone Through Various In Vitro Skin Models

Unprotected sunlight exposure is a risk factor for a variety of cutaneous cancers. Topically used dihydroxyacetone (DHA) creates, via Maillard reaction, chemically fixed keratin sunscreen in the stratum corneum with significant protection against UVA/Soret radiation. When used in conjunction with naphthoquinones a naphthoquinone-modified DHA Maillard reaction is produced that provides protection across the UVB/UVA/Soret spectra lasting up to 1 week, resisting sweating and contact removal. The aim of this study was to examine a simplified version of this formulation for effect on UV transmission and to determine if penetration levels merit toxicity concerns. Permeability was demonstrated for freshly prepared DHA (30 mg/mL) and lawsone (0.035 mg/mL) alone and in combination using a side-by-side diffusion apparatus at 37°C over 48 h across shed snake skin and dermatomed pig skin. These samples were then examined for effectiveness and safety. Concentrations were determined by HPLC and UPLC monitored from 250-500 nm. Lawsone flux significantly decreased across pig skin (20.8 (± 4.8) and 0.09 (± 0.1) mg/cm(2) h without and with DHA, respectively) but did not change across shed snake skin in the presence of DHA. Significantly reduced lawsone concentration was noted in donor chambers of combined solutions. Damage was not observed in any skins. Darker coloration with greater UV absorbance was observed in skins exposed to the combined solution versus individual solutions. This study confirmed that combined DHA and lawsone provided effective blocking of ultraviolet light through products bound in keratinized tissue. DHA permeation levels in pig skin suggest further in vitro and in vivo study is required to determine the safety of this system.

Inhibitory effect of gold nanoparticles on the D-ribose glycation of bovine serum albumin

Formation of advanced glycation end products (AGEs) by nonenzymatic glycation of proteins is a major contributory factor to the pathophysiology of diabetic conditions including senile dementia and atherosclerosis. This study describes the inhibitory effect of gold nanoparticles (GNPs) on the D-ribose glycation of bovine serum albumin (BSA). A combination of analytical methods including ultraviolet-visible spectrometry, high performance liquid chromatography, circular dichroism, and matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) mass spectrometry were used to determine the extent of BSA glycation in the presence of citrate reduced spherical GNPs of various sizes and concentrations. GNPs of particle diameters ranging from 2 nm to 20 nm inhibited BSA's AGE formation. The extent of inhibition correlated with the total surface area of the nanoparticles. GNPs of highest total surface area yielded the most inhibition whereas those with the lowest total surface area inhibited the formation of AGEs the least. Additionally, when GNPs' total surface areas were set the same, their antiglycation activities were similar. This inhibitory effect of GNPs on BSA's glycation by D-ribose suggests that colloidal particles may have a therapeutic application for the treatment of diabetes and conditions that promote hyperglycemia.