Japanese cedar pollinosis (JCPsis) is a major health problem that has increased over recent decades and impairs daily activities. According to Okubo et al. in the journal Allergology International, approximately 26.5% of people suffered from JCPsis in 2008.
Researchers from Yakult Central Institute and Shimoshizu National Hospital reported Lactobacillus plantarum YIT 0132 (LP0132) helps reduce the symptoms of JCPsis and suppresses the decrease in Treg cells.
Tregs are T cells which have a role in regulating or suppressing other cells in the immune system, and help prevent autoimmune disease.
Norihiro Kubota, senior researcher at Yakult Central Institute, Japan told NutraIngredients-Asia that previous research only studied the beneficial effects of LP0132 on allergy symptoms such as pollinosis, perennial allergic rhinitis, and atopic dermatitis. “It was unclear what kind of mechanism LP0132 uses to alleviate allergy symptoms. This study was conducted to confirm the reproducibility of the beneficial effects on pollinosis and to elucidate something about the mechanism of the fermented citrus juice.”
The findings were published in the journal Allergy.
The study recruited 100 adults with JCPsis and they were told to consume 125 mL of fermented citrus juice (n = 50) or unfermented citrus juice (placebo, n = 50). The experiment was conducted over eight weeks from mid‐February to mid‐April, the beginning to end of pollen season.
The fermented citrus juice consisted of Satsuma mandarin juice fermented with heat‐killed LP0132. Kubota told us LP0132 is a strain of lactic acid bacteria isolated from pickled vegetables.
Participants were asked to perform a weekly self‐assessment of JCPsis symptoms based on the Japanese Rhino‐conjunctivitis Quality of Life Questionnaire.
The primary outcome was total symptom score (TSS) in March (predicted peak season). Blood samples were collected at enrolment, late March, and during follow-up to evaluate the percentage of Treg cells.
Between weeks 3 to 6 (March), the average TSS did not differ significantly between both groups, although the LP0132 group had a significantly lower total nasal symptom score (TNSS) than the placebo group during the entire consumption period (weeks 0‐8).
The treatment group also experienced significantly lower TSS, symptom medication score (SMS), and TNSS at weeks 1 and 2 compared to the placebo group.
The percentage of Treg cells in late March was significantly higher in the LP0132 group than in the placebo group, showing that more Treg cells could help reduce some symptoms of JCPsis.
Despite the less than optimum result for the primary outcome where average TSS was not significant between both groups in the March period, researchers said this is the first clinical trial to demonstrate the ability of LP0132 to suppress the reduction in Treg cells in the peak pollen season.
Treg cells are reported to be reduced in patients with allergic rhinitis and increased by immunotherapy with a clinical response. The results of the present study suggest that Treg cells may be increased with the severity of pollinosis due to exposure to pollen.
Effects more prominent in early phase
In the present study, LP0132 alleviated JCPsis symptoms in the early phase and not the later phase, which Kubota explained: “The dispersal of pollen peaked around the middle phase. It is believed that since the subjects involved in this study had relatively severe pollinosis, their symptoms worsened from the middle phase and after when they were exposed to large amounts of pollen.
“For this reason, it may have been difficult to confirm the effects of LP0132 during that phase. Going forward, we would like to clarify how LP0132 demonstrated its beneficial effects in order to carry out an analysis on the details of the mechanism.”
Researchers also advised further studies are needed to examine whether circulating Treg cells decrease in the pollen season and if lactic acid bacteria is capable of inhibiting this seasonal change.
There were several limitations in the study, such as the specific subtypes of Treg cells induced by LP0132 to alleviate JCPsis symptoms were not examined. “For instance, experiments suggest that CD4 + CD25 + Foxp3 + RORγt + Treg cells induced by intestinal microbiota may suppress Th2 immune responses. IL‐10 levels in the blood samples were not measured to validate the LP0132 signature, which we will perform in a future study to further elucidate the mechanism underlying the action of LP0132,” researchers said.
In conclusion, citrus juice fermented with LP0132 alleviated JCPsis symptoms in the early season and suppressed reduction in circulating Treg cells in the peak season.
Currently, only the Yakult no Oishii Hakko Kajitsu (fermented tangerine drink) contains LP0132. It was released in 2018, and is free of allergy-specific ingredients such as milk, making it suitable for people with dairy allergies.
“Effect of Lactobacillus plantarum YIT 0132 on Japanese cedar pollinosis and regulatory T cells in adults”
Authors: Shuichi Suzuki, et al.