Taking L. reuteri KBL346 by Mouth Eases Flu Symptoms

Jenn Hoskins
2nd July, 2024

Taking L. reuteri KBL346 by Mouth Eases Flu Symptoms

Image Source: Natural Science News, 2024

Key Findings

  • Researchers at Seoul National University found that the probiotic L. reuteri KBL346, both live and heat-inactivated, can reduce the severity of influenza in mice
  • Mice treated with L. reuteri KBL346 showed improved body weight recovery, faster recovery times, and higher survival rates after influenza infection
  • The probiotic also modulated immune responses and altered the gut microbiome, contributing to reduced inflammation and enhanced recovery
Influenza virus infection remains a significant public health concern due to its high transmissibility and potential for severe complications. An emerging approach to mitigate the severity of influenza involves the use of probiotics, which are generally recognized as safe. A recent study conducted by researchers at Seoul National University evaluated the anti-influenza effects of a specific probiotic strain, Limosilactobacillus reuteri (L. reuteri) KBL346, isolated from the fecal samples of healthy South Koreans[1]. In this study, BALB/c mice were orally administered both live and heat-inactivated L. reuteri KBL346. Following infection with the influenza virus A/Puerto Rico/8/34 at 0.5 times the 50% lethal dose (LD50), the mice exhibited improved body weight recovery and accelerated recovery times. Additionally, when infected with a higher viral dose (4 times the LD50), the mice showed improved survival rates and reduced body weight loss. Notably, heat-inactivated L. reuteri KBL346 also decreased the viral titer in the lungs and lowered plasma immunoglobulin G (IgG) levels. The study revealed that L. reuteri KBL346 modulates the expression of genes related to the immune response. Specifically, it decreased the expression of interferon-γ and toll-like receptor 2 (Tlr2) in lung tissues, both of which play roles in inflammation. Furthermore, both live and heat-inactivated forms of L. reuteri KBL346 increased the expression of Adamts4, a gene associated with recovery post-infection, and decreased Tlr2 expression. The administration of L. reuteri KBL346 also altered the gut microbiome's α-diversity and the structure of the gut microbial community, which correlated with the degree of weight loss in the mice. These findings align with earlier studies that highlight the potential of probiotics in enhancing immune responses and providing protection against influenza. For instance, a study demonstrated that oral administration of Bifidobacterium breve YIT4064 in mice increased anti-influenza virus IgG antibodies in serum and offered enhanced protection against influenza virus infection[2]. Another study reported that heat-killed Lactobacillus plantarum L-137 stimulated the production of T helper (Th) 1-related cytokines and prolonged the survival time of mice infected with influenza virus[3]. Additionally, intranasal administration of Lactobacillus rhamnosus GG (LGG) was shown to enhance respiratory immune responses and increase the survival rate of mice infected with influenza virus[4]. The current study by Seoul National University builds upon these findings by demonstrating that both live and heat-inactivated L. reuteri KBL346 can modulate the immune response and gut microbiome to alleviate the severity of influenza. The reduction in inflammatory cytokines and the promotion of recovery-related genes suggest that L. reuteri KBL346 has a multifaceted role in combating influenza infection. In summary, the study provides compelling evidence that L. reuteri KBL346, both in live and heat-inactivated forms, can effectively reduce the severity of influenza infection in mice. This probiotic strain modulates key immune responses and alters the gut microbiome, highlighting its potential as a therapeutic option against influenza. The findings align with previous research on the benefits of probiotics in enhancing immune responses and offer a promising avenue for future studies and potential clinical applications.

MedicineHealthAnimal Science


Main Study

1) Oral Administration of Limosilactobacillus reuteri KBL346 Ameliorates Influenza Virus A/PR8 Infection in Mouse

Published 29th June, 2024


Related Studies

2) Protection against influenza virus infection of mice fed Bifidobacterium breve YIT4064.

Journal: Clinical and diagnostic laboratory immunology, Issue: Vol 6, Issue 2, Mar 1999

3) Oral administration of heat-killed Lactobacillus plantarum L-137 enhances protection against influenza virus infection by stimulation of type I interferon production in mice.


4) Intranasal administration of Lactobacillus rhamnosus GG protects mice from H1N1 influenza virus infection by regulating respiratory immune responses.


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