No abstract

Diffuse large B-cell lymphoma (DLBCL) is a clinically heterogeneous lymphoid malignancy that is the most common type of lymphoma in Japan. Previous studies have demonstrated that patients with DLBCL have a poor prognosis due to increased levels of indoleamine 2,3-dioxygnase and kynurenine (KYN). However, the roles of metabolites acting downstream of KYN and associated enzymes are not fully understood. The present study investigated the role of kynurenine 3-monooxygenase (KMO), which catalyzes the conversion of KYN to 3-hydroxykynurenine (3-HK), using serum samples from patients with DLBCL and human DLBCL cell lines with different KMO expression [STR-428 cells with high levels of KMO expression (KMO high ) and KML-1 cells with low levels of KMO expression (KMO low )]. Serum samples from 28 patients with DLBCL and 34 healthy volunteers were used to investigate the association between prognosis and KMO activity or 3-HK levels. Furthermore, to investigate the roles of KMO and its related metabolites, STR-428 and KML-1 cell lines, and the lymph nodes of patients with DLBCL were analyzed by reverse transcription-quantitative PCR for KMO, KYNU, 3-hydroxyanthranilate-3,4-dioxygenase and quinolinate phosphoribosyltransferase, by western blotting, and immunohistochemical or immunofluorescence staining for KMO, and by cell viability and NAD + /NADH assays. KYN pathway metabolites in serum samples were measured by HPLC. Serum 3-HK levels were regulated independently of serum KYN levels, and increased serum 3-HK levels and KMO activity were found to be associated with worse disease progression. Notably, the addition of KMO inhibitors and 3-HK negatively and positively regulated the viability of DLBCL cells, respectively. Furthermore, NAD + levels in KMO high STR-428 cells were significantly higher than those in KMO low KML-1 cells. These results suggested that 3-HK generated by KMO activity may be involved in the regulation of DLBCL cell viability via NAD + synthesis.

Various cancer cells require massive amounts of glucose as an energy source for their dysregulated growth. Although D-allose, a rare sugar, inhibits tumor cell growth via inhibition of glucose uptake, a few cells can survive after treatment. However, the mechanism by which D-allose-resistant cells are generated remains unclear. Here, we investigated the properties of D-allose-resistant cells and evaluated the efficacy of combined treatment with this rare sugar and antitumor drugs. To this end, we established a D-allose-resistant tumor cell line and prepared a C57BL/6J mouse tumor xenograft model using Lewis lung carcinoma (LLC) cells. Xenograft-bearing mice were treated with D-allose (9 g/kg) and/or hydroxychloroquine (HCQ, 60 mg/kg), an autophagy inhibitor, for two weeks. Although D-allose inhibited LLC cell growth in a dose-dependent manner, a few cells survived. The upregulation of LC3-II, a classical autophagy marker, and the downregulation of mTOR and its downstream molecule Beclin1 were observed in established D-allose-resistant LLC cells, which were more sensitive to cell death induced by HCQ. Similarly, in the tumor xenograft model, the tumor volume in mice co-treated with D-allose and HCQ was considerably smaller than that in untreated or HCQ-treated mice. Importantly, the administration of D-allose induced autophagy selectively at the tumor site of the xenograft-bearing mice. These results provide a new therapeutic strategy targeting autophagy which is induced in tumor cells by D-allose administration, and may be used to improve therapies for lung cancer.

Sepsis is a systemic inflammatory disease caused by a bacterial infection that leads to severe mortality, especially in elderly patients, because of an excessive immune response and impaired regulatory functions. Antibiotic treatment is widely accepted as the first-line therapy for sepsis; however, its excessive use has led to the emergence of multidrug-resistant bacteria in patients with sepsis. Therefore, immunotherapy may be effective in treating sepsis. Although CD8+ regulatory T cells (Tregs) are known to have immunomodulatory effects in various inflammatory diseases, their role during sepsis remains unclear. In this study, we investigated the role of CD8+ Tregs in an LPS-induced endotoxic shock model in young (8–12 wk old) and aged (18–20 mo old) mice. The adoptive transfer of CD8+ Tregs into LPS-treated young mice improved the survival rate of LPS-induced endotoxic shock. Moreover, the number of CD8+ Tregs in LPS-treated young mice increased through the induction of IL-15 produced by CD11c+ cells. In contrast, LPS-treated aged mice showed a reduced induction of CD8+ Tregs owing to the limited production of IL-15. Furthermore, CD8+ Tregs induced by treatment with the rIL-15/IL-15Rα complex prevented LPS-induced body wight loss and tissue injury in aged mice. In this study, to our knowledge, the induction of CD8+ Tregs as novel immunotherapy or adjuvant therapy for endotoxic shock might reduce the uncontrolled immune response and ultimately improve the outcomes of endotoxic shock.