Commensal bacteria in the gut microbiome has many important roles in health, including the support of immune function. Many factors about the symbiotic relationship between the gut microbiome and human health remain under investigation. Research into the gut microbiome and its impact on health and disease also includes studies into various probiotic strains that may promote microbial diversity and gut health.* One such strain is Immuno-LP20™, a trademarked strain of heat-treated Lactobacillus plantarum L-137 (HK L-137), which was originally found in fermented foods.

Research into HK L-137 has demonstrated the potential for this probiotic strain to support immune function. HK L-137 supports the body’s balance of T-helper (Th)1/Th2 type cells and immune response defenses to help the body’s protection against pathogenic microbes, viruses, and allergies.* Th1 cells stimulate responses that involve cellular immune responses such as macrophage activation and the production of immunoglobulin (Ig)M and IgG. Th2 cells stimulate a humoral immune response, such as antibody production.

One potential mechanism for HK L-137 immune-modulating actions is that it induces interleukin-12, a cytokine that triggers a Th1 immune response. HK L-137 contains higher levels of lipoteichoic acid on its cell surface. This allows for more phagocytosis by scavenger receptor A, which supports immune function. These properties may make HK L-137 a more potential IL-12 inducer than other heat-killed Lactobacillus strains. HK L-137 may also support immune function by affecting the percent change of concanavalin A–induced proliferation of peripheral blood mononuclear cells (PBMCs). HK L-137 may also promote a healthy inflammatory response.

Clinical studies have assessed the efficacy of HK L-137 to promote immune health. One randomized controlled trial with 16 adults had participants taking 10 mg of HK L-137 or a placebo before and after getting the influenza vaccine for 8 weeks. Those who took the HK L-137 experienced significantly higher levels of interferon-beta, which is an early effector of innate immune responses that may also promote Th-1 type responses and regulate adaptive immunity.

Another randomized controlled trial assessed 60 adult participants taking 10 mg of HK L-137 daily for 12 weeks compared to a placebo. The probiotic group experienced beneficial effects on their Th-1 related immune functions and acquired immunity. This included sustained increases in the Th1/Th2 ratio and concanavalin A–induced proliferation of PBMC and improved health-related quality of life.

Another study examined the potential for HK L-137 to support immune function in healthy individuals with significant psychological stress, which may impact the immune system. This randomized, double-blind, placebo-controlled, parallel study had 78 participants who were under psychological stress. The group taking 10 mg HK L-137 for 12 weeks experienced a significantly reduced incidence of upper respiratory tract infections (URTIs) compared to the control group. The treatment group also experienced a significant negative correlation of duration of HK L-147 supplementation and URTI incidence, duration of infection, severity, and duration of medication.

Many dietary and lifestyle factors promote immune function to support the body’s defenses against potential pathogenic bacteria, viruses, and allergens. Consuming foods that promote microbial diversity in the gut microbiome not only supports gut health but also promotes immune health due to the close relationship between the two. Research continues into other potential mechanisms for supporting the gut microbiome and immune function, such as using certain probiotic strains like Immuno-LP20™.

By Kendra Whitmire, MS, CNS