Top Ten Hot Topics in Probiotics Research (Part One)

At the time of formulating the national medium- and long-term science and technology development plan for 2021-2035 and the 14th Five-Year Plan, in order to focus on the current research hotspots in probiotic science and make basic judgments on the key common problems that need to be solved urgently in the field of probiotic research, starting from April 2020, the Probiotic Branch of the Chinese Institute of Food Science and Technology (hereinafter referred to as the 'Branch') organized relevant researchers to conduct frequency statistics and analysis of keywords in the literature on probiotics from the China National Knowledge Infrastructure (CNKI) journal database and the Web of Science database from 2001 to 2020 based on bibliometrics, combined with the clustering analysis of high-frequency keywords in the field of probiotics by relevant scientific and technological workers in the scientific and industrial sectors, and refined to form the 'Top Ten Hotspots in Probiotic Scientific Research'.ProbioticsTop Ten Hotspots in Scientific Research.

1. Probiotics and Digestive Health

With the change in people's dietary structure, the incidence of intestinal diseases is rising, and the types of diseases are gradually changing. Many researchers have attempted to prevent intestinal diseases through dietary intervention to maintainintestinal health.Probiotics are an important ingredient in dietary intervention. Based on current research results, the role of probiotics in maintaining intestinal health may be achieved through the following pathways: probiotics can promote intestinal health through antioxidant effects, regulating the content and activity of certain enzymes in the intestine, and can also reduce the incidence of cancer and inhibit its development by directly enhancing the host's immune response or by firmly binding to carcinogenic substances, thus maintaining intestinal health. The pathways through which probiotics maintain intestinal health do not act in isolation but are the result of multiple pathways working together.

2. Probiotics and Immune Regulation and Allergic Reactions

Intestinal bacteria play a key role in microbial stimulation and mucosal immunity, providing specific signals for the body to generate sufficient immune stimulation and the development of immune cells.

Yang et al. treated ovalbumin (OVA) allergic mice with oral infant BB for 2 weeks, resulting in a significant decrease in OVA-specific IgE and IgG levels in mouse serum, and a significant reduction in the release of IL-4, IL-5, and IL-13 in their spleen cells, thereby reducing the incidence of temperature drop and diarrhea in mice. In addition, the study found that the protective effect of BB on allergic mice was also related to the antioxidant enzyme superoxide dismutase (SOD), meaning that BB can mediate an antioxidant effect on dendritic cells through the cyclic adenosine monophosphate/protein kinase A (cAMP/PKA) signaling pathway, thereby alleviating oxidative stress responses, while also inhibiting signal transducer and activator of transcription (STAT) 6, further reducing the expression of mucin (TIM) 4. Specific strains of Lactobacillus can upregulate co-stimulatory molecules produced by semi-mature DCs, leading to the generation of T regulatory cells and the formation of immune tolerance, reducing the production of pro-inflammatory factors.

Huang et al. conducted a comprehensive analysis of 13 studies published in PubMed, Medline, Cochrane Library, Scopus, and OVID databases, finding that LGG and Lactobacillus plantarum had no significant effect on the specific dermatitis index score of children with atopic dermatitis; however, fermented Lactobacillus, Salivarius (PMA006), and mixed different strains had a significant effect. Gulliver et al. studied the treatment of adult chronic hand eczema with probiotics. After giving patients oral probiotic enteric-coated capsules containing 30 billion colony-forming units (including Lactobacillus acidophilus, Lactobacillus casei, and Lactobacillus rhamnosus) for 12 weeks, clinical scores and reported results of adult chronic hand eczema were recorded, finding that most subjects showed significant improvement in hand dermatitis, especially with rapid relief of itching symptoms.

3. Probiotics and Metabolic Syndrome

Metabolic syndrome (MS) is a group of syndromes centered on insulin resistance, leading to metabolic disorders of proteins, fats, carbohydrates, etc., with central obesity, hypertension, glucose metabolism, and dyslipidemia as the main clinical manifestations. Studies have shown that feeding high-fat diets to mouse models and administering bifidobacteria resulted in a significant decrease in inflammation-related factors such as serum endotoxin lipopolysaccharide (PS) and inflammatory factors plasminogen activator inhibitor-1 (PAI-1), inducible nitric oxide synthase (iNOS), and monocyte chemoattractant protein-1 (MCP-1). Lactobacillus plantarum DSM15313 can also lower blood sugar, improve glucose tolerance, and enhance insulin resistance. Other researchers supplemented probiotics—Lactobacillus rhamnosus and Lactobacillus gasseri—to mice fed high-fat or high-sucrose diets, confirming that these probiotics have anti-diabetic and anti-obesity effects, with mechanisms including improving insulin resistance, lowering BMI, reducing leptin and insulin levels, increasing adiponectin production, and upregulating gluconeogenesis genes and skeletal muscle glucose transporter-4 mRNA expression.

4. Probiotics and Oral Health

Currently, there is a wealth of research and summaries on the efficacy and mechanisms of probiotics in the gastrointestinal field, and as the mouth is the starting point of the digestive tract, the oral microecology has certain similarities with gastrointestinal microecology, thus the impact of probiotics on oral diseases is receiving increasing attention from scholars.

Oral infectious diseases mainly include caries, apical periodontitis, periodontal disease, and other soft tissue and space infections in the craniofacial region. Odontogenic halitosis and oral candidiasis are also considered related to oral microbial infections. The bacteria causing oral infectious diseases are mainly resident oral bacteria. Changes in the external environment lead to an imbalance in oral microecology, with overgrowth of resident flora and opportunistic pathogens being the main causes of oral infectious diseases. Therefore, intervening in the factors that cause oral microecological imbalance, reversing the pathological composition of oral microbial communities, and restoring oral microecological balance are key to effectively preventing and treating oral infectious diseases.

Probiotics and Oral Candidiasis. DeBarros et al. pointed out that Lactobacillus can effectively inhibit the growth of Candida albicans after co-cultivation. Pereira et al. demonstrated in mouse experiments that using Lactobacillus rhamnosus significantly reduced the incidence of Candida albicans infection. Clinical studies have shown that probiotic intervention is significantly effective in the prevention and treatment of Candida albicans.

Probiotics and Halitosis. 90% of halitosis originates from the oral cavity, with some also coming from the digestive tract, and probiotics can address both oral and intestinal issues. The inhibition of halitosis by probiotics may be related to their suppression of the opportunistic growth of periodontal anaerobic bacteria and the inhibition of putrefactive bacteria in the intestine, thereby alleviating halitosis caused by both oral and digestive tract sources.

Probiotics and periodontitis. Becirovic et al. demonstrated in vitro that Lactobacillus can inhibit the growth of periodontal pathogens including Porphyromonas gingivalis, Fusobacterium nucleatum, and Aggregatibacter actinomycetemcomitans. Animal experiments by Gatej et al. found that feeding Lactobacillus rhamnosus to periodontitis model mice significantly reduced the degree of alveolar bone loss and gingival inflammation. In clinical trials, Invernici et al. randomly divided 41 patients with periodontal disease into two groups; the experimental group received conventional scaling and root planing plus lozenges containing bifidobacteria, while the control group only received scaling and root planing. After one month, the experimental group showed significant reductions in periodontal disease-related indices such as bleeding index, gingival index, and probing bleeding compared to the control group.

Citation:

[1] Probiotics and intestinal health

[2] Research progress on the correlation between probiotics and immune regulation and allergic diseases

[3] The potential role and research progress of probiotics in metabolic syndrome

[4] Research progress on the prevention and treatment of oral infectious diseases with probiotics

Note: This article is for informational purposes only and should not be considered medical advice.