Quantifying lactulose and mannitol using LC-MS/MS in a clinical study of children with environmental enteric disease

Dysfunction of the intestinal epithelium barrier (DIEB) is frequent and can lead to serious complications in early childhood when diagnosis and clinical intervention are limited, especially in children with environmental enteric disease and malnutrition. The use of refined analytical techniques is increasingly necessary in this context. This study aimed to validate the high-performance liquid chromatography method coupled with tandem mass spectrometry (LC-MS/MS) to measure DIEB by lactulose:mannitol ratio detection (LM test) in samples of children with different social profiles from Fortaleza, Ceará. The first experimental set was conducted to validate the method through laboratory parameters, such as limit of detection (LD), limit of quantification (LQ), specificity/selectivity, linearity, accuracy, and precision. All validation parameters achieved detection and recovery standards within an acceptable coefficient of variation. Community samples (human development index (HDI) from 0.000 to ≤0.499) were obtained from children from the cohort study Malnutrition-Enteric Diseases, Fortaleza-CE (environmental enteric disease; EED group). The control group samples came from a school located in a region with a high HDI (>0.8). Mannitol excretion was lower in the EED group than in the control group (P<0.0001). On the other hand, LM was higher in this group compared to the control group (P<0.0001). For the first time, a robust analytical approach was used to detect biomarkers of environmental enteropathy (LM) in community samples, confirming with high-sensitivity the damage to the intestinal epithelial barrier function in populations living in low socio-economic conditions.

Induced acute hyperglycemia modifies the barrier function of the intestinal epithelium by tissue inflammation and tight junction disruption resulting in hydroelectrolytic secretion in an animal model

Diabetic-metabolic syndrome (MetS-D) has a high prevalence worldwide, in which an association with the rupture of the intestinal epithelium barrier function (IEBF) has been pointed out, but the functional and morphological properties are still not well understood. This study aimed to evaluate the impact of acute hyperglycemia diabetes on intestinal tight junction proteins, metabolic failure, intestinal ion and water transports, and IEBF parameters. Diabetes was induced in male Rattus norvegicus (200-310 g) with 0.5 mL of streptozotocin (70 mg/kg). Glycemic and clinical parameters were evaluated every 7 days, and intestinal parameters were evaluated on the 14th day. The MetS-D animals showed a clinical pattern of hyperglycemia, with increases in the area of villi and crypts, lactulose:mannitol ratio, myeloperoxidase (MPO) activity, and intestinal tissue concentrations of malondialdehyde (MDA), but showed a reduction in reduced glutathione (GSH) when these parameters were compared to the control. The MetS-D group had increased secretion of Na+, K+, Cl-, and water compared to the control group in ileal tissue. Furthermore, we observed a reduction in mRNA transcript of claudin-2, claudin-15, and NHE3 and increases of SGLT-1 and ZO-1 in the MetS-D group. These results showed that MetS-D triggered intestinal tissue inflammation, oxidative stress, complex alterations in gene regulatory protein transcriptions of intestinal transporters and tight junctions, damaging the IEBF and causing hydroelectrolyte secretion.