AbstractAllogeneic hematopoietic stem cell transplantation (SCT) is a curative therapy for various hematologic disorders. Graft-versus-host disease (GVHD) and infections are the major complications of SCT, and their close relationship has been suggested. In this study, we evaluated a link between 2 complications in mouse models. The intestinal microbial communities are actively regulated by Paneth cells through their secretion of antimicrobial peptides, α-defensins. We discovered that Paneth cells are targeted by GVHD, resulting in marked reduction in the expression of α-defensins, which selectively kill noncommensals, while preserving commensals. Molecular profiling of intestinal microbial communities showed loss of physiologic diversity among the microflora and the overwhelming expansion of otherwise rare bacteria Escherichia coli, which caused septicemia. These changes occurred only in mice with GVHD, independently on conditioning-induced intestinal injury, and there was a significant correlation between alteration in the intestinal microbiota and GVHD severity. Oral administration of polymyxin B inhibited outgrowth of E coli and ameliorated GVHD. These results reveal the novel mechanism responsible for shift in the gut flora from commensals toward the widespread prevalence of pathogens and the previously unrecognized association between GVHD and infection after allogeneic SCT.

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Mammalian DNA methylation patterns are established by two de novo DNA methyltransferases, DNMT3A and DNMT3B, which exhibit both redundant and distinctive methylation activities. However, the related molecular basis remains undetermined. Through comprehensive structural, enzymology and cellular characterization of DNMT3A and DNMT3B, we here report a multi-layered substrate-recognition mechanism underpinning their divergent genomic methylation activities. A hydrogen bond in the catalytic loop of DNMT3B causes a lower CpG specificity than DNMT3A, while the interplay of target recognition domain and homodimeric interface fine-tunes the distinct target selection between the two enzymes, with Lysine 777 of DNMT3B acting as a unique sensor of the +1 flanking base. The divergent substrate preference between DNMT3A and DNMT3B provides an explanation for site-specific epigenomic alterations seen in ICF syndrome with DNMT3B mutations. Together, this study reveals distinctive substrate-readout mechanisms of the two DNMT3 enzymes, implicative of their differential roles during development and pathogenesis.

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Chronic GVHD (cGVHD) is a main cause of late death and morbidity after allogeneic hematopoietic cell transplantation, but its pathogenesis remains unclear. We investigated the roles of Th subsets in cGVHD with the use of a well-defined mouse model of cGVHD. In this model, development of cGVHD was associated with up-regulated Th1, Th2, and Th17 responses. Th1 and Th2 responses were up-regulated early after BM transplantation, followed by a subsequent up-regulation of Th17 cells. Significantly greater numbers of Th17 cells were infiltrated in the lung and liver from allogeneic recipients than those from syngeneic recipients. We then evaluated the roles of Th1 and Th17 in cGVHD with the use of IFN-γ-deficient and IL-17-deficient mice as donors. Infusion of IFN-γ(-/-) or IL-17(-/-) T cells attenuated cGVHD in the skin and salivary glands. Am80, a potent synthetic retinoid, regulated both Th1 and Th17 responses as well as TGF-β expression in the skin, resulting in an attenuation of cutaneous cGVHD. These results suggest that Th1 and Th17 contribute to the development of cGVHD and that targeting Th1 and Th17 may therefore represent a promising therapeutic strategy for preventing and treating cGVHD.

Brown Norway kininogen-deficient rats had very low levels of plasma kininogens and lower levels of plasma prekallikrein, compared with those of normal rats of the same strain. Systolic blood pressure, determined by the tail-cuff method, of 5-week-old kininogen-deficient rats (106±0.4 mm Hg, n=l) and the rate of systolic blood pressure increase with age were not different from those in normal rats. Weekly injections of deoxycorticosterone acetate (5 mg/kg s.c) with 1% sodium chloride solution in drinking water after uninephrectomy at 7 weeks of age caused a gradual increase in the blood pressure of normal rats, reaching a plateau at 18 weeks of age, whereas that of deficient rats rose rapidly to 158 ±6 mm Hg 2 weeks after the start of treatment and continued to increase slightly, becoming significantly higher than normal rats at 8, 9,10,11, and 12 weeks of age (p<0.05 or 0.01). The levels of urinary prokallikrein and active kallikrein were slightly higher in deficient rats before deoxycorticosterone acetate-salt treatment but were not significantly increased after this treatment, whereas these levels in normal rats were increased 3.6-and 4.7-fold by this treatment Urinary free kinin, collected from the ureter in untreated deficient rats, was below the detection limit The plasma level of low molecular weight kininogen, the substrate of glandular kallikrein, was decreased in normal rats during the treatment Continuous subcutaneous injection of aprotinin by an osmotic pump to normal rats induced significant increase in blood pressure. These results indicate that glandular kallikrein may play a suppressive role in deoxycorticosterone acetate-salt hypertension. {Hypertension 1991;17:806-813) I t was pointed out early on that kallikrein may be related to hypertensive diseases. 1 Recently, urinary kallikrein levels were reported to be lower in patients with essential hypertension than in normotensive controls 2 " 5 but were normal in renal artery stenosis and raised in pheochromocytoma and primary aldosteronism.2 Spontaneously hypertensive rats and rats with deoxycorticosterone acetate (DOCA)-salt hypertension showed greater increases in urinary kallikrein excretion than normotensive Wistar control rats from the National Institutes of Health.3 However, the role of the endogenous kallikrein-kinin system in development of hypertension remains unclear. The kallikrein-kinin system is a system for generating vasodilating peptides, bradykinin, or kallidin, by means of proteolytic enzymes, plasma, or glandular kallikrein, from its own precursor protein, high molecular weight (HMW) or low molecular weight (LMW) kininogen. Brown Norway Katholiek (BNKa) rats have been reported to have a congenitally abnormal kallikrein-kinin system 6 -8 and have been extensively studied and compared with normal rats of the same strain (BN-Kitasato [BN-Ki]). 9- 19 In a previous study, it was reported that not only HMW but also LMW kininogens were lacking in plasma from mutant BN-Ka rats, and only T-kininogen was present. -12 Because of the lack of...

We describe a 55-year-old man with acute myelogenous leukemia who developed breakthrough Trichosporon asahii fungemia during 5 days of micafungin treatment. Although the patient's clinical condition improved considerably after the start of voriconazole treatment, blood culture results remained positive for T. asahii for 3 days, and fever persisted for 7 days thereafter. The patient achieved complete hematological remission, and he received successful consolidation chemotherapy without developing Trichosporon infection with the prophylactic use of voriconazole therapy. This case report illustrates that voriconazole may be useful in the treatment of disseminated T. asahii infection in neutropenic patients.

Key Points Mn stimulates macrophages via Dectin-2 to induce donor Th17 differentiation after allogeneic bone marrow transplantation. Mn-induced Th17 cells accumulate in the lungs to cause pulmonary GVHD.