Differences in Metabolite Composition of Aloe barbadensis Mill. Extracts Lead to Differential Effects on Human Blood T Cell Activity In Vitro.

Aloe barbadensis Mill. (Aloe) is used for diverse therapeutic properties including immunomodulation. However, owing to the compositionally complex nature of Aloe, bioactive component(s) responsible for its beneficial properties, though thought to be attributed to polysaccharides (acemannan), remain unknown. We therefore aimed to determine the metabolite composition of various commercial Aloe extracts and assess their effects on human blood T cell activity in vitro. Peripheral blood mononuclear cells (PBMC) from healthy donors were stimulated polyclonally in presence or absence of various Aloe extracts. T cell phenotype and proliferation were investigated by flow cytometry. Aloe extracts were analyzed using targeted 1H-NMR spectroscopy for standard phytochemical quality characterization and untargeted gas chromatography mass spectrometry (GC-MS) for metabolite profiling. Aloe extracts differing in their standard phytochemical composition had varying effects on T cell activation, proliferation, apoptosis, and cell-death in vitro, although this was not related to the acemannan content. Furthermore, each Aloe extract had its own distinct metabolite profile, where extracts rich in diverse sugar and sugar-derivatives were associated with reduced T cell activity. Our results demonstrate that all commercial Aloe extracts are unique with distinct metabolite profiles, which lead to differential effects on T cell activity in vitro, independent of the acemannan content.

Randomized clinical trial: Effects of Aloe barbadensis Mill. extract on symptoms, fecal microbiota and fecal metabolite profiles in patients with irritable bowel syndrome.

BACKGROUND: Aloe barbadensis Mill. (Aloe) with potential prebiotic effects has been suggested to reduce symptoms in patients with irritable bowel syndrome (IBS). We therefore aimed to determine the effects of an Aloe extract on symptoms of IBS, and evaluate whether effects may be mediated by fecal microbiota and metabolites in a randomized, double-blind, controlled trial. METHODS: Patient with IBS diagnosed according to the ROME III criteria (all subtypes), received Aloe or control treatment (inulin) for 4 weeks. IBS Symptom Severity Score (IBS-SSS) was assessed, and fecal samples collected before and at end of treatment. Fecal microbiota composition and metabolomic profile were determined. KEY RESULTS: In total, 160 IBS patients completed the study. The overall severity of IBS symptoms was reduced in both Aloe and control treatment groups (P < .001, both groups, comparing baseline vs end of treatment), without difference between groups (P = .62). The frequency of responders (IBS-SSS reduction ≥ 50) did not differ between Aloe treatment (n = 33, 39%) and control (n = 34, 45%) (P = .49). However, fecal microbiota and metabolite profiles differed between Aloe, but not control treatment responders and non-responders both before and after treatment. CONCLUSION: In a mixed group of IBS patients, Aloe was not superior to control treatment, although it showed potential to reduce IBS symptom severity in subsets of IBS patients which could be predicted by fecal microbiota and metabolite profiles. ClinicalTrials.gov no: NCT01400048.

Effects of Aloe barbadensis Mill. extract (AVH200®) on human blood T cell activity in vitro.

ETHNOPHARMACOLOGICAL RELEVANCE: Aloe barbadensis Mill. (Aloe vera) is a widely used medicinal plant well reputed for its diverse therapeutic applications. It has been used for thousands of years in folk medicine to treat various conditions and the Aloe vera gel has been reported to possess anti-inflammatory as well as immunostimulatory and immunomodulatory properties. However, the mode of action is still unclear. AIM OF THE STUDY: The aim of this study was determine the effects of two well-defined A. barbadensis Mill. extracts AVH200® and AVE200 on human blood T cells in vitro. MATERIALS AND METHODS: Peripheral blood mononuclear cells (PBMC) from healthy donors were stimulated polyclonally in the presence or absence of AVH200® and AVE200. The T cell phenotype was investigated by flow cytometry, cell proliferation was determined by CFSE dye and thymidine assay, respectively and cytokine secretion was determined by MSD® Multi-Spot Assay system and ELISA. RESULTS: The presence of AVH200® resulted in a reduced expression of CD25 among CD3(+) T cells and suppression of T cell proliferation in a dose dependent manner. Furthermore, AVH200® reduced the expression of CD28 on CD3(+) T cells. AVH200® also reduced the secretion of IL-2, IFN-γ and IL-17A in PBMC cultures. The AVH200® dose dependent reduction in T cell activation and proliferation recorded in the cell cultures was not due to apoptosis or cell death. Additionally, AVH200® was found to be more effective as compared to AVE200 in reducing T cell activation and proliferation. CONCLUSION: AVH200® has the potential to reduce the activation, proliferation and cytokine secretion of healthy human blood T cells. Our study suggests that AVH200® has a suppressive effect on human blood T cells in vitro.