Cow milk is a nourishing food containing numerous essential nutrients. In Japan, the consumption of cow milk is thought to enhance resistance to exhaustion-related diseases. Although several nutrients in cow milk, such as lactoferrin, are thought to modulate immune cells, the mechanisms remain unclear. Recently, the immunoregulatory functions of foodderived microRNAs or exosomes have been reported. Therefore, we studied the effects of exosomes derived from cow milk (CM-Exs) on immune cells in the present study. We obtained blood samples from healthy adult donors with the approval of the ethics committee. Peripheral blood mononuclear cells (PBMCs) were stimulated with CM-Exs in the absence or presence of interleukin-2 (IL-2) and IL-12. Cell surface markers and intracellular cytokine production were analysed by flow cytometry. CM-Ex stimulation enhanced the expression of CD69 on NK cells. Although CM-Ex stimulation alone did not induce interferon-c (IFN-c) production by NK cells or cdT cells, simultaneous stimulation with CM-Ex, IL-2 and IL-12 significantly enhanced IFN-c production. In conclusion, cow milk consumption alone may not activate immune cells; however, CM-Exs could enhance immune cells under inflammatory conditions.

The incidence of infections with nontuberculous mycobacteria (NTM) has been increasing worldwide. The emergence of multidrug-resistant NTM is a serious clinical concern, and a vaccine for NTM has not yet been developed. We previously developed a new recombinant Bacillus Calmette–Guérin (rBCG) vaccine encoding the antigen 85B (Ag85B) protein of Mycobacterium kansasii—termed rBCG-Mkan85B—which was used together with a booster immunization with plasmid DNA expressing the same M. kansasii Ag85B gene (DNA-Mkan85B). We reported that rBCG-Mkan85B/DNA-Mkan85B prime–boost immunization elicited various NTM strain-specific CD4+ and CD8+ T cells and induced Mycobacterium tuberculosis-specific immunity. In this study, to investigate the protective effect against M. kansasii infection, we challenged mice vaccinated with a rBCG-Mkan85B or rBCG-Mkan85B/DNA-Mkan85B prime–boost strategy with virulent M. kansasii. Although BCG and rBCG-Mkan85B immunization each suppressed the growth of M. kansasii in the mouse lungs, the rBCG-Mkan85B/DNA-Mkan85B prime–boost vaccination reduced the bacterial burden more significantly. Moreover, the rBCG-Mkan85B/DNA-Mkan85B prime–boost vaccination induced antigen-specific CD4+ and CD8+ T cells. Our data suggest that rBCG-Mkan85B/DNA-Mkan85B prime–boost vaccination effectively enhances antigen-specific T cells. Our novel rBCG could be a potential alternative to clinical BCG for preventing various NTM infections.

The Asian tiger mosquito, Aedes albopictus, is a common mosquito in East and Southeast Asia, but its habitats have expanded to the American, African and Australian continents, Europe and many other areas. Aedes albopictus can transmit some important arboviruses that cause human mortality. To control the global spread of this mosquito, genetic analyses of A. albopictus populations have been undertaken throughout the world. In Japan, however, few attempts have been made to characterize the population structures of these mosquitos. In this study, adult A. albopictus populations were sampled from seven parks in the urban area of Tokyo, and analyses of the mitochondrial cytochrome c oxidase subunit 1 (COI) gene base sequences revealed small genetic variations. Only three haplotypes were identified, and most of the samples belonged to a single haplotype. In addition, despite a developed international trade network, no establishment of A. albopictus populations from multiple origins was found. We also evaluated the genetic diversity outside Tokyo using data from a previous study for comparison and found that the genetic diversity in the urban area of Tokyo was lower than that in Nagasaki City (Japan) and in other countries, including the USA and Italy, where A. albopictus populations from Japan have been established.

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Background The COVID‐19 vaccine is effective in preventing severe cases of COVID‐19. For women, gynecological adverse events, such as menstrual irregularities and irregular bleeding, could be a concern after COVID‐19 vaccination. In this study, we investigated gynecological adverse events in the vaccinated Japanese female population. Methods We conducted a survey‐based study with health‐care workers, including medical doctors and nurses, medical coworkers, and medical university faculty, staff, and students, at a single medical school and affiliated hospital in Japan. We used McNemar's test and network analysis. Results Overall, we obtained 819 responses, and 424 were from females. After the exclusion of contradictory answers, 309 surveys were finally considered appropriate for the analysis. The frequencies of abnormal bleeding were 0.6%, 1.0%, and 3.0% for the first, second, and third doses, respectively. An irregular menstrual cycle was more common than abnormal bleeding: 1.9%, 4.9%, and 6.6% for the first, second, and third doses, respectively. Network analysis revealed that abnormal bleeding and an irregular menstrual cycle were not associated with other adverse reactions. Conclusion The present study showed that the effects of COVID‐19 vaccination on menstruation seem limited.