Probiotic Mechanisms Affecting Glucose Homeostasis: A Scoping Review

Abstract

The maintenance of a healthy status depends on the coexistence between the host organism and the microbiota. Early studies have already focused on the nutritional properties of probiotics, which may also contribute to the structural changes in the gut microbiota, thereby affecting host metabolism and homeostasis. Maintaining homeostasis in the body is therefore crucial and is reflected at all levels, including that of glucose, a simple sugar molecule that is an essential fuel for normal cellular function. Despite numerous clinical studies that have shown the effect of various probiotics on glucose and its homeostasis, knowledge about the exact function of their mechanism is still scarce. The aim of our review was to select in vivo and in vitro studies in English published in the last eleven years dealing with the effects of probiotics on glucose metabolism and its homeostasis. In this context, diverse probiotic effects at different organ levels were highlighted, summarizing their potential mechanisms to influence glucose metabolism and its homeostasis. Variations in results due to different methodological approaches were discussed, as well as limitations, especially in in vivo studies. Further studies on the interactions between probiotics, host microorganisms and their immunity are needed.

Keywords: glucose; homeostasis; mechanism; metabolism; probiotic.

Figure 1

Effect of probiotics on adipose tissue. TNF-α: tumour necrosis factor alpha; TGF-β: transforming growth factor beta; IL-6: interleukin-6; IL-1β: interleukin 1 beta; AdipoR2; adiponectin receptor 2; TGF-β: transforming growth factor beta; SIRT1: sirtuin (silent mating type information regulation 2 homolog) 1; PPARα: peroxisome proliferator-activated receptor α; PPAR-γ: peroxisome proliferator-activated receptor gamma; FGF21: fibroblast growth factor 21; GLUT4: glucose transporter 4; ↓: decrease; ↑: increase.

Figure 2

Effect of probiotics on skeletal muscles. GSK-3β: glycogen synthase kinase 3 beta; PI3K/AKT: phosphoinositide 3-kinase/phosphorylated protein kinase B signalling pathway; PPAR-γ: peroxisome proliferator-activated receptor gamma; GLUT4: glucose transporter 4; AMPK: 5′ adenosine monophosphate-activated protein kinase; ↓: decrease; ↑: increase.

Figure 3

Effect of probiotics on liver. Keap1/Nrf2: Kelch-like ECH-associated protein 1/Nuclear factor-erythroid factor 2-related factor 2; Gnas: Gs protein alpha-subunit; PKA: cAmp-dependent protein kinase; CRTC2: CREB-regulated transcriptional coactivator 2; PEPCK: phosphoenolpyruvate carboxykinase; G6PC: glucose-6-phosphatase catalytic subunit; ACE2/Ang-(1–7)/MasR): angiotensin-converting enzyme 2/angiotensin-(1–7)/mitochondrial assembly receptor; GSK-3β: glycogen synthase kinase 3 beta; FOXO1: Forehead Box O1; GS: glycogen synthase; PFK-1: phosphofructokinase-1; TNF-α: tumour necrosis factor alpha; IL-6: interleukin-6; IL-1β: interleukin 1 beta; PI3K/AKT: phosphoinositide 3-kinase/phosphorylated protein kinase B signalling pathway; PCK1: phosphoenolpyruvate carboxykinase 1; GLUT2: glucose transporter 2; ↓: decrease; ↑: increase.

Figure 4

Effect of probiotics on kidney and pancreas. IL-6: interleukin-6; IRS-1: insulin receptor substrate 1 protein; eNOS: endothelial nitric oxide synthase; AKT: protein kinase B; SGLT2: sodium-glucose cotransporter 2; p65: transcription nuclear factor NF-kappa-B p65 subunit; TNF-α: tumour necrosis factor alpha; TLR4: toll-like receptor 4; IL-1β: interleukin 1 beta; IL-10: interleukin 10; PDX-1: insulin promoter factor 1; ClC-2: chloride channel protein 2; ↓: decrease; ↑: increase.

Figure 5

Effect of probiotics on intestine. SCFA: short-chain fatty acids; PI3K/AKT: phosphoinositide 3-kinase/phosphorylated protein kinase B signalling pathway; GPR43/41: G protein-coupled receptor 43/41; GLP-1: glucagon-like polypeptide-1; TLR4: toll-like receptor 4; TLR2: toll-like receptor 2; TNF-α: tumour necrosis factor alpha; IL-6: interleukin-6; GLUT2: glucose transporter 2; GLUT5: glucose transporter 5; SGLT1: sodium-glucose cotransporter 1; ↓: decrease; ↑: increase; *, ", ^, °, #: each symbol stands for a different probiotic effect, which has a corresponding effect on glucose metabolism and homeostasis.