Diabetic retinopathy (DR) is the most common microvascular complication of diabetes and the leading cause of visual impairment in working-age adults. Patients with diabetes often develop DR despite appropriate control of systemic risk factors, suggesting the involvement of other pathogenic factors. We hypothesize that the plasma metabolic signature of DR is distinct and resolvable from that of diabetes alone. A nested population-based case-control metabonomic study was first performed on 40 DR cases and 40 control subjects with diabetes using gas chromatography–mass spectrometry. Eleven metabolites were found to be correlated with DR, and the majority were robust when adjusted for metabolic risk factors and confounding kidney disease. The metabolite markers 2-deoxyribonic acid; 3,4-dihydroxybutyric acid; erythritol; gluconic acid; and ribose were validated in an independent sample set with 40 DR cases, 40 control subjects with diabetes, and 40 individuals without diabetes. DR cases and control subjects with diabetes were matched by HbA1c in the validation set. Activation of the pentose phosphate pathway was identified from the list of DR metabolite markers. The identification of novel metabolite markers for DR provides insights into potential new pathogenic pathways for this microvascular complication and holds translational value in DR risk stratification and the development of new therapeutic measures.

Evidence is accumulating that the establishment of the gut microbiome in early life influences the development of atopic eczema. In this longitudinal study, we used integrated multi-omics analyses to infer functional mechanisms by which the microbiome modulates atopic eczema risk. We measured the functionality of the gut microbiome and metabolome of 63 infants between ages 3 weeks and 12 months with well-defined eczema cases and controls in a sub-cohort from the Growing Up in Singapore Toward healthy Outcomes (GUSTO) mother-offspring cohort. At 3 weeks, the microbiome and metabolome of allergen-sensitized atopic eczema infants were characterized by an enrichment of Escherichia coli and Klebsiella pneumoniae, associated with increased stool D-glucose concentration and increased gene expression of associated virulence factors. A delayed colonization by beneficial Bacteroides fragilis and subsequent delayed accumulation of butyrate and propionate producers after 3 months was also observed. Here, we describe an aberrant developmental trajectory of the gut microbiome and stool metabolome in allergen sensitized atopic eczema infants. The infographic describes an impaired developmental trajectory of the gut microbiome and metabolome in allergen-sensitized atopic eczema (AE) infants and infer its contribution in modulating allergy risk in the Singaporean mother-offspring GUSTO cohort. The key microbial signature of AE is characterized by (1) an enrichment of Escherichia coli and Klebsiella pneumoniae which are associated with accumulation of pre-glycolysis intermediates (D-glucose) via the trehalose metabolic pathway, increased gene expression of associated virulence factors (invasin, adhesin, flagellin and lipopolysaccharides) by utilizing ATP from oxidative phosphorylation and delayed production of butyrate and propionate, (2) depletion of Bacteroides fragilis which resulted in lower expression of immunostimulatory bacterial cell envelope structure and folate (vitamin B9) biosynthesis pathway, and (3) accompanied depletion of bacterial groups with the ability to derive butyrate and propionate through direct or indirect pathways which collectively resulted in reduced glycolysis, butyrate and propionate biosynthesis. Graphical abstract

Fatalities stemming from hepatotoxicity associated with the clinical use of lapatinib (Tykerb), an oral dual tyrosine kinase inhibitor (ErbB-1 and ErbB-2) used in the treatment of metastatic breast cancer, have been reported. We investigated the inhibition of CYP3A4 by lapatinib as a possible cause of its idiosyncratic toxicity. Inhibition of CYP3A4 was time-, concentration-, and NADPH-dependent, with k_inact = 0.0202 min⁻¹ and K_i = 1.709 μM. The partition ratio was approximately 50.9. Addition of GSH did not affect the rate of inactivation. Testosterone protected CYP3A4 from inactivation by lapatinib. The characteristic Soret peak associated with a metabolite-intermediate complex was not observed for lapatinib during spectral difference scanning. However, reduced carbon monoxide (CO)-difference spectroscopy did reveal a 43% loss of the spectrally detectable CYP3A4-CO complex in the presence of lapatinib. Incubation of either lapatinib or its dealkylated metabolite with human liver microsomes in the presence of GSH resulted in the formation of a reactive metabolite (RM)-GSH adduct derived from the O-dealkylated metabolite of lapatinib. In addition, coincubation of lapatinib with ketoconazole inhibited the formation of the RM-GSH adduct. In conclusion, we demonstrated for the first time that lapatinib is a mechanism-based inactivator of CYP3A4, most likely via the formation and further oxidation of its O-dealkylated metabolite to a quinoneimine that covalently modifies the CYP3A4 apoprotein and/or heme moiety.