Abstract

This study presents the discovery and application of Lacticaseibacillus rhamnosus LRa66, a novel probiotic strain exhibiting significant capabilities of blood glucose and lipid reduction. Isolated from human breast milk, LRa66 demonstrates superior tolerance to gastric acid, intestinal fluid, and bile salts. It has been shown to effectively ameliorate metabolic syndrome symptoms, particularly hyperglycemia and hyperlipidemia. The findings indicate that LRa66 could be a promising candidate for developing therapeutic agents for managing metabolic disorders.

Introduction

Metabolic syndrome (MS) encompasses a cluster of conditions, including obesity, hypertension, dyslipidemia, and insulin resistance, which collectively elevate the risk of cardiovascular diseases. The growing prevalence of obesity and related metabolic disorders highlights the urgent need for effective interventions. Probiotics, particularly those influencing gut microbiota, have emerged as potential therapeutic agents in managing MS.

Materials and Methods

- Isolation and Identification

Lacticaseibacillus rhamnosus LRa66 was isolated from human breast milk. The isolation process involved serial dilutions and culture on MRS agar plates containing selective antibiotics to inhibit non-target bacteria. Isolated colonies were purified, and the strain was identified and deposited with the China General Microbiological Culture Collection Center (CGMCC No. 24282).

- In Vitro Characterization

The LRa66 strain was evaluated for its tolerance to gastric acid (pH 2.0), bile salts (0.3%), and intestinal fluid (pH 8.0). Adhesion to Caco-2 cells was assessed to determine its potential for gut colonization. Additionally, the strain's ability to inhibit pathogenic bacteria and utilize functional oligosaccharides was tested.

- Animal Studies

Male mice with induced type 2 diabetes mellitus (T2DM) were administered LRa66. Blood samples were collected to measure serum triglycerides (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), insulin levels, and inflammatory markers (IL-10, TNF-α, and IL-1β).

Results

- Tolerance and Adhesion

LRa66 exhibited robust tolerance to acidic and bile conditions, with survival rates exceeding 90% in simulated gastric and intestinal environments. The strain adhered well to Caco-2 cells, indicating a high potential for gut colonization.

- In Vivo Efficacy

Administration of LRa66 significantly reduced serum TG, TC, and LDL-C levels while increasing HDL-C levels. Insulin sensitivity improved, as indicated by reduced fasting insulin levels. Inflammatory markers showed a notable decrease, with elevated IL-10 levels and reduced TNF-α and IL-1β production.

Discussion

The probiotic strain LRa66 demonstrated significant potential in managing MS through modulation of lipid metabolism and glycemic control. The strain's ability to endure gastrointestinal conditions and adhere to intestinal cells suggests its effectiveness in vivo. LRa66's anti-inflammatory properties further contribute to its therapeutic potential.

Conclusion

Lacticaseibacillus rhamnosus LRa66 presents a promising probiotic candidate for managing metabolic disorders. Its dual functionality in lowering blood glucose and lipids, combined with anti-inflammatory effects, positions it as a valuable component in therapeutic formulations for metabolic syndrome.

Keywords: Lactobacillus rhamnosus LRa66, metabolic syndrome, probiotics, blood glucose reduction, lipid reduction, gut microbiota, inflammation