In order to explore the effect of forest bathing on human immune function, we investigated natural killer (NK) activity; the number of NK cells, and perforin, granzymes and granulysin-expression in peripheral blood lymphocytes (PBL) during a visit to forest fields. Twelve healthy male subjects, age 37-55 years, were selected with informed consent from three large companies in Tokyo, Japan. The subjects experienced a three-day/two-night trip in three different forest fields. On the first day, subjects walked for two hours in the afternoon in a forest field; and on the second day, they walked for two hours in the morning and afternoon, respectively, in two different forest fields. Blood was sampled on the second and third days, and NK activity; proportions of NK, T cells, granulysin, perforin, and granzymes A/B-expressing cells in PBL were measured. Similar measurements were made before the trip on a normal working day as the control. Almost all of the subjects (11/12) showed higher NK activity after the trip (about 50 percent increased) compared with before. There are significant differences both before and after the trip and between days 1 and 2 in NK activity. The forest bathing trip also significantly increased the numbers of NK, perforin, granulysin, and granzymes A/B-expressing cells. Taken together, these findings indicate that a forest bathing trip can increase NK activity, and that this effect at least partially mediated by increasing the number of NK cells and by the induction of intracellular anti-cancer proteins.

We previously reported that a forest bathing trip enhanced human NK activity, number of NK cells, and intracellular anti-cancer proteins in lymphocytes. In the present study, we investigated how long the increased NK activity lasts and compared the effect of a forest bathing trip on NK activity with a trip to places in a city without forests. Twelve healthy male subjects, age 35-56 years, were selected with informed consent. The subjects experienced a three-day/two-night trip to forest fields and to a city, in which activity levels during both trips were matched. On day 1, subjects walked for two hours in the afternoon in a forest field; and on day 2, they walked for two hours in the morning and afternoon, respectively, in two different forest fields; and on day 3, the subjects finished the trip and returned to Tokyo after drawing blood samples and completing the questionnaire. Blood and urine were sampled on the second and third days during the trips, and on days 7 and 30 after the trip, and NK activity, numbers of NK and T cells, and granulysin, perforin, and granzymes A/B-expressing lymphocytes in the blood samples, and the concentration of adrenaline in urine were measured. Similar measurements were made before the trips on a normal working day as the control. Phytoncide concentrations in forest and city air were measured. The forest bathing trip significantly increased NK activity and the numbers of NK, perforin, granulysin, and granzyme A/B-expressing cells and significantly decreased the concentration of adrenaline in urine. The increased NK activity lasted for more than 7 days after the trip. In contrast, a city tourist visit did not increase NK activity, numbers of NK cells, nor the expression of selected intracellular anti-cancer proteins, and did not decrease the concentration of adrenaline in urine. Phytoncides, such as alpha-pinene and beta-pinene were detected in forest air, but almost not in city air. These findings indicate that a forest bathing trip increased NK activity, number of NK cells, and levels of intracellular anti-cancer proteins, and that this effect lasted at least 7 days after the trip. Phytoncides released from trees and decreased stress hormone may partially contribute to the increased NK activity.

We previously found that forest environments reduced stress hormones such as adrenaline and noradrenaline and showed the relaxing effect both in male and female subjects. In the present study, we investigated the effects of walking under forest environments on cardiovascular and metabolic parameters. Sixteen healthy male subjects (mean age 57.4 ± 11.6 years) were selected after obtaining informed consent. The subjects took day trips to a forest park in the suburbs of Tokyo and to an urban area of Tokyo as a control in September 2010. On both trips, they walked for 2 h in the morning and afternoon on a Sunday. Blood and urine were sampled on the morning before each trip and after each trip. Blood pressure was measured on the morning (0800) before each trip, at noon (1300), in the afternoon (1600) during each trip, and on the morning (0800) after each trip. The day trip to the forest park significantly reduced blood pressure and urinary noradrenaline and dopamine levels and significantly increased serum adiponectin and dehydroepiandrosterone sulfate (DHEA-S) levels. Walking exercise also reduced the levels of serum N-terminal pro-B-type natriuretic peptide (NT-proBNP) and urinary dopamine. Taken together, habitual walking in forest environments may lower blood pressure by reducing sympathetic nerve activity and have beneficial effects on blood adiponectin and DHEA-S levels, and habitual walking exercise may have beneficial effects on blood NT-proBNP levels.

Aim Chronic endometritis (CE) is a disease of continuous and subtle inflammation characterized by the infiltration of plasma cells in the endometrial stromal area. Although the clinical significance of CE has been thought in clinical practice for a long time because it is either asymptomatic or presents with subtle symptoms, recent studies have shown the potential adverse effects of CE on fertility. In the present review, we focus on the concept, diagnosis, etiology, pathophysiology, diagnosis, impact on reproduction and treatment for it to understand CE. Methods The published articles were reviewed. Results The prevalence of CE has been found to be 2.8–56.8% in infertile women, 14–67.5% in women with recurrent implantation failure (RIF), and 9.3–67.6% in women with recurrent pregnancy loss. Microorganisms are thought to be a main cause of CE, since antibiotic treatment has been reported to be an effective therapy for CE. Common bacteria are frequently detected in the uterine cavity of CE patients by microbial culture. In CE endometrium, the prevalence of immune cells and decidualization has been reported to be modified, and these modifications are thought to adversely affect fertility. The gold standard for the diagnosis of CE is the histological detection of plasma cells in the stromal area of the endometrium in endometrial specimens, although universally accepted criteria for the diagnosis of CE have not been determined. The treatment currently thought to be most effective for the recovery of fertility in CE is administration of oral antibiotics. Patients whose CE has been cured have been reported to have a higher ongoing pregnancy rate, clinical pregnancy rate, and implantation rate compared with patients with persistent CE. Conclusion CE greatly affects implantation and impairs fertility. Antibiotic administration is an effective therapeutic option. Pregnancy rate in in vitro fertilization is improved when CE is cured by antibiotic.

We previously reported that the forest environment enhanced human natural killer (NK) cell activity, the number of NK cells, and intracellular anti-cancer proteins in lymphocytes, and that the increased NK activity lasted for more than 7 days after trips to forests both in male and female subjects. To explore the factors in the forest environment that activated human NK cells, in the present study we investigate the effect of essential oils from trees on human immune function in twelve healthy male subjects, age 37-60 years, who stayed at an urban hotel for 3 nights from 7.00p.m. to 8.00a.m. Aromatic volatile substances (phytoncides) were produced by vaporizing Chamaecyparis obtusa (hinoki cypress) stem oil with a humidifier in the hotel room during the night stay. Blood samples were taken on the last day and urine samples were analysed every day during the stay. NK activity, the percentages of NK and T cells, and granulysin, perforin, granzyme AlB-expressing lymphocytes in blood, and the concentrations of adrenaline and noradrenaline in urine were measured. Similar control measurements were made before the stay on a normal working day. The concentrations of phytoncides in the hotel room air were measured. Phytoncide exposure significantly increased NK activity and the percentages of NK, perforin, granulysin, and granzyme AlB-expressing cells, and significantly decreased the percentage of T cells, and the concentrations of adrenaline and noradrenaline in urine. Phytoncides, such as a-pinene and -pinene, were detected in the hotel room air. These findings indicate that phytoncide exposure and decreased stress hormone levels may partially contribute to increased NK activity.The forest environment has been enjoyed by humans for a long time because of the quiet atmosphere, beautiful scenery, mild climate, and clean fresh air. We previously reported that the forest environment enhanced human natural killer (NK) cell activity, the number of NK and NKT cells, and intracellular anti-cancer proteins in lymphocytes, and that the increased NK activity lasted for more than 7 days after the trips to forests both in male and female subjects (1-5). However, it is not clear what kind of factors in the forest environment activated human NK cells. We speculate that aromatic volatile substances derived from trees, including monoterpenes and sesquiterpenes, called phytoncides, such as a-pinene and limonene (6), may play an important role. Thus, the effects of phytoncides, such as a-pinene,