SUMMARY:We surveyed Rickettsiales bacteria, including Rickettsia, Ehrlichia, Anaplasma, and Neoehrlichia, in wild sika deer (Cervus nippon nippon) from Shizuoka prefecture, Japan. In spleen samples from 187 deer, Anaplasma phagocytophilum (deer type), A. bovis, and A. centrale were successfully detected by PCR assay targeting to 16S rDNA or p44/msp2, and their positive rates were 96.3z (180/187), 53.5z (100/187), and 78.1z (146/187), respectively. Additionally, 2 or 3 Anaplasma species could be detected from a single deer in 165 spleen samples (88.2z), indicating dual or triple infection. In contrast, A. phagocytophilum (human type) 16S rDNA, Rickettsia gltA, Ehrlichia p28/omp-1, and Neoehrlichia 16S rDNA could not be amplified. The serological test of 105 deer serum samples by immunofluorescence assay showed that the detection of antibodies against antigens of A. phagocytophilum HZ (US-human isolate) and Rickettsia japonica YH were 29.5z (31/105) and 75.2z (79/105), respectively. These findings suggest that A. phagocytophilum (deer type), A. centrale, and A. bovis are highly dominant and prevalent in wild sika deer from Shizuoka, a central region of Japan, and that the antibodies against some Rickettsiales bacteria have also been retained in deer blood.

Wheat bran has a high dietary fiber content. In this study, we investigated the effects of short-term intake of wheat bran on intestinal environment in a murine model. Mice were fed with AIN-93G for 1 week, followed by experimental diets containing wheat bran with an average particle size of 53 μm (powdered) or 350 μm (granulated) for 1 additional week. During a 4-week period (twice-repeated feeding cycles), the ratio of bacteria belonging to the families Prevotellaceae and S24-7 increased in murine feces after intake of both particle-size diets. Furthermore, the amount of short fatty acids, particularly butyric acid, and cecal immunoglobulin A were significantly increased in the powdered wheat bran group, probably by the changes in intestinal microbiota composition. These findings may potentially explain many of the health benefits through the alteration of intestinal microbiota, even after short-term intake of wheat bran.

Wheat bran, a by-product generated in large amounts during wheat processing, consists of 36.5% to 52.4% total dietary fiber. In this study, we investigated the effects of wheat bran intake on the intestinal tract immune system through the modulation of gut microbiota. Balb/c mice were fed with AIN-93G diets containing wheat bran with 2 different particle sizes (average particle size of 53 µm: powdered wheat bran; PWB, and 350 µm: granulated wheat bran; WB) as dietary fibers for 4 weeks. In the wheat bran intake groups, short chain fatty acids (SCFAs: acetic acid, propionic acid, and butyric acid) in the feces were increased after the intake of both particle-size diets, especially in the PWB group, in which the increase occurred immediately. 16S rRNA-based metagenomics of the fecal microbiota revealed that the Shannon Index (α-diversity) and weighted UniFrac distances (β-diversity) in wheat bran intake groups were significantly higher than those in the Control group, and the ratio of the certain family within the order Clostridiales in the fecal microbiota was increased after wheat bran intake, probably some including SCFA-producing bacteria. CXCR5, which is a key surface marker expressed on T follicular helper (Tfh) cells, tended to increase at the expression level in wheat bran intake groups. In addition, the amounts of secretory immunoglobulin A (IgA) and the proportion of IgA-binding bacteria in the feces from wheat bran intake groups were significantly higher than those from the Control group. These findings suggest that wheat bran may enhance Tfh-mediated IgA production in the intestine by SCFA increment through the modulation of gut microbiota and is expected to maintain and improve a healthy intestinal environment.