title: Orally Administered Salacia reticulata Extract Reduces H1N1 Influenza Clinical Symptoms in Murine Lung Tissues Putatively Due to Enhanced Natural Killer Cell Activity.
abstract: Influenza is a major cause of respiratory tract infection. Although most cases do not require further hospitalization, influenza periodically causes epidemics in humans that can potentially infect and kill millions of people. To countermeasure this threat, new vaccines need to be developed annually to match emerging influenza viral strains with increased resistance to existing vaccines. Thus, there is a need for finding and developing new anti-influenza viral agents as alternatives to current treatments. Here, we tested the antiviral effects of an extract from the stems and roots of Salacia reticulata (SSRE), a plant rich in phytochemicals, such as salacinol, kotalanol, and catechins, on H1N1 influenza virus-infected mice. Following oral administration of 0.6 mg/day of SSRE, the incidence of coughing decreased in 80% of mice, and only one case of severe pulmonary inflammation was detected. Moreover, when compared with mice given Lactobacillus casei JCM1134, a strain previously shown to help increase in vitro natural killer (NK) cell activity, SSRE-administered mice showed greater and equal NK cell activity in splenocytes and pulmonary cells, respectively, at high effector cell:target cell ratios. Next, to test whether or not SSRE would exert protective effects against influenza in the absence of gut microbiota, mice were given antibiotics before being inoculated influenza virus and subsequently administered SSRE. SSRE administration induced an increase in NK cell activity in splenocytes and pulmonary cells at levels similar to those detected in mice not treated with antibiotics. Based on our results, it can be concluded that phytochemicals in the SSRE exerted protective effects against influenza infection putatively via modulation of the immune response, including enhancement of NK cell activity, although some protective effects were not necessarily through modulation of gut microbiota. Further investigation is necessary to elucidate the molecular mechanisms underlying the protective effects of SSRE against influenza infection.
authors.affiliation: Kyoto Institute of Nutrition and Pathology , Kyoto , Japan.
authors.forename: Gustavo A
authors.initials: GA
authors.lastname: Romero-Pérez
authors.affiliation: Laboratory of Animal Science, Department of Agricultural and Life Sciences, Kyoto Prefectural University , Kyoto , Japan.
authors.forename: Masayo
authors.initials: M
authors.lastname: Egashira
authors.affiliation: Laboratory of Animal Science, Department of Agricultural and Life Sciences, Kyoto Prefectural University , Kyoto , Japan.
authors.forename: Yuri
authors.initials: Y
authors.lastname: Harada
authors.affiliation: Laboratory of Animal Science, Department of Agricultural and Life Sciences, Kyoto Prefectural University , Kyoto , Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tsuruta
authors.affiliation: Life Science Research Laboratories, Research and Development Management Headquarters, Fujifilm Corporation , Kanagawa , Japan.
authors.forename: Yuriko
authors.initials: Y
authors.lastname: Oda
authors.affiliation: Life Science Research Laboratories, Research and Development Management Headquarters, Fujifilm Corporation , Kanagawa , Japan.
authors.forename: Fumitaka
authors.initials: F
authors.lastname: Ueda
authors.affiliation: Kyoto Institute of Nutrition and Pathology, Kyoto, Japan; Laboratory of Animal Science, Department of Agricultural and Life Sciences, Kyoto Prefectural University, Kyoto, Japan.
authors.forename: Takamitsu
authors.initials: T
authors.lastname: Tsukahara
authors.affiliation: Laboratory of Animal Hygiene, Department of Agricultural and Life Sciences, Kyoto Prefectural University , Kyoto , Japan.
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Tsukamoto
authors.affiliation: Laboratory of Animal Science, Department of Agricultural and Life Sciences, Kyoto Prefectural University , Kyoto , Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Inoue
keywords: H1N1 influenza virus; Lactobacillus casei JCM1134; Salacia reticulata extract; antibiotics; gut microbiota; natural killer cells; pulmonary cells; splenocytes