Metabolomics, an analytical study with high-throughput profiling, helps to understand interactions within a biological system. Small molecules, called metabolites or metabolomes with the size of <1500 Da, depict the status of a biological system in a different manner. Currently, we are in need to globally analyze the metabolome and the pathways involved in healthy, as well as diseased conditions, for possible therapeutic applications. Metabolome analysis has revealed high-abundance molecules during different conditions such as diet, environmental stress, microbiota, and disease and treatment states. As a result, it is hard to understand the complete and stable network of metabolites of a biological system. This review helps readers know the available techniques to study metabolomics in addition to other major omics such as genomics, transcriptomics, and proteomics. This review also discusses the metabolomics in various pathological conditions and the importance of metabolomics in therapeutic applications.

The aim of this study was to investigate expression and relative contribution of human thiamin transporter (hTHTR)-2 toward overall carrier-mediated thiamin uptake by human intestinal epithelial cells. Northern blot analysis showed that the message of the hTHTR-2 is expressed along the native human gastrointestinal tract with highest expression being in the proximal part of small intestine. hTHTR-2 protein was found, by Western blot analysis, to be expressed at the brush-border membrane (BBM), but not at the basolateral membrane, of native human enterocytes. This pattern of expression was confirmed in studies using a fusion protein of hTHTR-2 with the enhanced green fluorescent protein (hTHTR2-EGFP) expressed in living Caco-2 cells grown on filter. Pretreating Caco-2 cells (which also express the hTHTR-2 at RNA and protein levels) with hTHTR-2 gene-specific small interfering RNA (siRNA) led to a significant ( P < 0.01) and specific inhibition (48%) in carrier-mediated thiamin uptake. Similarly, pretreating Caco-2 cells with siRNA that specifically target hTHTR-1 (which is expressed in Caco-2 cells) also significantly ( P < 0.01) and specifically inhibited (by 56%) carrier-mediated thiamin uptake. When Caco-2 cells were pretreated with siRNAs against both hTHTR-2 and hTHTR-1 genes, an almost complete inhibition in carrier-mediated thiamin uptake was observed. These results show that the message of hTHTR-2 is expressed along the human gastrointestinal tract and that expression of its protein in intestinal epithelia is mainly localized to the apical BBM domain. In addition, results show that this transporter plays a significant role in carrier-mediated thiamin uptake in human intestine.

It has been well established that human intestinal and liver epithelial cells transport biotin via an Na⁺-dependent carrier-mediated mechanism. The sodium-dependent multivitamin transport (SMVT), a biotin transporter, is expressed in both cell types. However, the relative contribution of SMVT toward total carrier-mediated uptake of physiological (nanomolar) concentrations of biotin by these cells is not clear. Addressing this issue is important, especially in light of the recent identification of a second human high-affinity biotin uptake mechanism that operates at the nanomolar range. Hence, we employed a physiological approach of characterizing biotin uptake by human-derived intestinal Caco-2 and HepG2 cells at the nanomolar concentration range. We also employed a molecular biology approach of selectively silencing the endogenous SMVT of these cells with specific small interfering RNAs (siRNAs), then examining carrier-mediated biotin uptake. The results showed that in both Caco-2 and HepG2 cells, the initial rate of biotin uptake as a function of concentration over the range of 0.1 to 50 nM to be linear. Furthermore, we found that the addition of 100 nM unlabeled biotin, desthiobiotin, or pantothenic acid to the incubation medium had no effect on the uptake of 2.6 nM ^[3H]biotin. Pretreatment of Caco-2 and HepG2 cells with SMVT specific siRNAs substantially reduced SMVT mRNA and protein levels. In addition, carrier-mediated [³H]biotin (2.6 nM) uptake by Caco-2 and HepG2 cells was severely ( P 0.01) inhibited by the siRNAs pretreatment. These results demonstrate that the recently described human high-affinity biotin uptake system is not functional in intestinal and liver epithelial cells. In addition, the results provide strong evidence that SMVT is the major (if not the only) biotin uptake system that operates in these cells.

Propionibacterium acnes is an opportunistic pathogen which has become notorious owing to its ability to form a recalcitrant biofilm and to develop drug resistance. The current study aimed to develop anti-biofilm treatments against clinical isolates of P. acnes under in vitro and in vivo conditions. A combination of ellagic acid and tetracycline (ETC; 250 μg ml⁻¹ + 0.312 μg ml⁻¹) was determined to effectively inhibit biofilm formation by P. acnes (80–91%) without affecting its growth, therefore potentially limiting the possibility of the bacterium attaining resistance. In addition, ETC reduced the production of extracellular polymeric substances (EPS) (20–26%), thereby making P. acnes more susceptible to the human immune system and antibiotics. The anti-biofilm potential of ETC was further substantiated under in vivo conditions using Caenorhabditis elegans. This study reports a novel anti-biofilm combination that could be developed as an ideal therapeutic agent with broad cosmeceutical and pharmaceutical applicability in the era of antibiotic resistance.