Takashi Watanabe's research while affiliated with Tohoku University and other places

Ly6C hi monocytes migrate to injured sites and induce inflammation in the acute phase of tissue injury. However, once the causes of tissue injury are eliminated, monocyte-derived macrophages contribute to the resolution of inflammation and tissue repair. It remains unclear whether the emergence of these immunoregulatory macrophages is attributed to the phenotypic conversion of inflammatory monocytes in situ or to the recruitment of bone marrow–derived regulatory cells de novo. Here, we identified a subpopulation of Ly6C hi monocytes that contribute to the resolution of inflammation and tissue repair. Ym1 ⁺ Ly6C hi monocytes greatly expanded in bone marrow during the recovery phase of systemic inflammation or tissue injury. Ym1 ⁺ Ly6C hi monocytes infiltrating into an injured site exhibited immunoregulatory and tissue-reparative phenotypes. Deletion of Ym1 ⁺ Ly6C hi monocytes resulted in delayed recovery from colitis. These results demonstrate that a distinct monocyte subpopulation destined to act in immunoregulation is generated in bone marrow and participates in resolution of inflammation and tissue repair.

Genetic variations within cytochrome P450 2B6 (CYP2B6) contribute to inter-individual variation in the metabolism of clinically important drugs, including cyclophosphamide, bupropion, methadone and efavirenz (EFZ). In this study, we performed an in vitro analysis of 40 CYP2B6 allelic variant proteins including seven novel variants identified in 1070 Japanese individuals. Wild-type and 39 variant proteins were heterologously expressed in 293FT cells to estimate the kinetic parameters (Km, Vmax, and CLint) of EFZ 8-hydroxylation and 7-ethoxy-4-trifluoromethylcoumarin (7-ETC) O-deethylation activities. The concentrations of CYP2B6 variant holo-enzymes were measured by using carbon monoxide (CO)-reduced difference spectroscopy, and the wild-type and 28 variants showed a peak at 450 nm. The kinetic parameters were measured for the wild-type and 24 variant proteins. The values for the remaining 15 variants could not be determined because the enzymatic activity was not detected at the highest substrate concentration used. Compared to wild-type, six variants showed significantly decreased EFZ 8-hydroxylation CLint values, while these values were significantly increased in another six variants, including CYP2B6.6. Although 7-ETC O-deethylation CLint values of CYP2B6 variants did not differ significantly from that of CYP2B6.1, the CLint ratios obtained for 7-ETC O-deethylation were highly correlated with EFZ 8-hydroxylation. Furthermore, three-dimensional structural modeling analysis was performed to elucidate the mechanism of changes in the kinetics of CYP2B6 variants. Our findings could provide evidence of the specific metabolic activities of the CYP2B6 proteins encoded by these variant alleles.

Macrophages manifest distinct phenotype according to the organs in which they reside. In addition, they flexibly switch their character in adaptation to the changing environment. However, the molecular basis that explains the conversion of the macrophage phenotype has so far been unexplored. We find that CD169+ macrophages change their phenotype by regulating the level of a transcription factor Maf both in vitro and in vivo in C57BL/6J mice. When CD169+ macrophages were exposed to bacterial components, they expressed an array of acute inflammatory response genes in Maf-dependent manner and simultaneously start to downregulate Maf. This Maf suppression is dependent on accelerated degradation through proteasome pathway and microRNA-mediated silencing. The downregulation of Maf unlocks the NF-E2-related factor 2-dominant, cytoprotective/antioxidative program in the same macrophages. The present study provides new insights into the previously unanswered question of how macrophages initiate proinflammatory responses while retaining their capacity to repair injured tissues during inflammation.

Lamina propria (LP) macrophages are constantly exposed to commensal bacteria, and are refractory to those antigens in an interleukin (IL)-10-dependent fashion. However, the mechanisms that discriminate hazardous invasion by bacteria from peaceful coexistence with them remain elusive. Here we show that CD169 þ macrophages reside not at the villus tip, but at the bottom-end of the LP microenvironment. Following mucosal injury, the CD169 þ macrophages recruit inflammatory monocytes by secreting CCL8. Selective depletion of CD169 þ macrophages or administration of neutralizing anti-CCL8 antibody ameliorates the symptoms of experimentally induced colitis in mice. Collectively, we identify an LP-resident macrophage subset that links mucosal damage and inflammatory monocyte recruitment. Our results suggest that CD169 þ macrophage-derived CCL8 serves as an emergency alert for the collapse of barrier defence, and is a promising target for the suppression of mucosal injury.

Cytochrome P450 2B6 (CYP2B6) is a potentially important enzyme for the metabolism of clinical drugs, and it exhibits genetic polymorphism. Thus far, 29 allelic variants of CYP2B6 (CYP2B6*1-CYP2B6*29) have been identified. This study aimed to investigate whether 26 of the variant alleles of CYP2B6 (CYP2B6*2-CYP2B6*21 and CYP2B6*23-CYP2B6*28) affect its kinetics in the metabolism of 7-ethoxy-4-trifluoromethylcoumarin (7-EFC) and selegiline. Wild-type CYP2B6.1 and the allelic variants were heterologously expressed in COS-7 cells. In-vitro kinetic analysis revealed that when compared with the wild-type protein CYP2B6.1, CYP2B6.10 and CYP2B6.14 exhibited significantly lower V(max)/K(m) values for selegiline N-demethylation. The kinetic parameters of CYP2B6.8, CYP2B6.11, CYP2B6.12, CYP2B6.13, CYP2B6.15, CYP2B6.18, CYP2B6.21, CYP2B6.24, and CYP2B6.28 could not be determined because these enzymes were inactive in the deethylation of 7-EFC and the N-demethylation/N-depropagylation of selegiline. These findings provide useful information for further genotype-phenotype studies on interindividual differences in the metabolism of CYP2B6 substrate drugs.