Nivolumab receptor occupancy on effector regulatory T cells predicts clinical benefit.

Immune checkpoint inhibitor discovery represents a turning point in cancer treatment. However, the response rates of solid tumors remain ~10%-30%; consequently, prognostic and immune-related adverse event (irAE) predictors are being explored. The programmed cell death protein 1 (PD-1) receptor occupancy (RO) of PD-1 inhibitors depends on the number of peripheral blood lymphocytes and their PD-1 expression levels, suggesting that the RO may be related to efficacy and adverse events. As PD-1 inhibition affects each T-cell subset differently, the RO of each cell population must be characterized. However, relevant data have not been reported, and the prognostic relevance of this parameter is not known. In this study, we aimed to clarify the association between the nivolumab RO in each T-cell population and patient prognosis and reveal the development of irAEs in nivolumab-treated patients. Thirty-two patients were included in the study, and the mean follow-up period was 364 days. The nivolumab RO on effector regulatory T cells (eTregs) was significantly lower in the group that presented clinical benefits, and a significant negative association was observed between PD-1 occupancy on eTregs and all-cause mortality. The results suggest that the nivolumab RO on eTregs may be a prognostic factor in PD-1 inhibitor therapy, implying that the inhibition of PD-1/PD-ligand 1 (PD-L1) signaling on eTregs may attenuate antitumor effects.

Butyricimonas is a key gut microbiome component for predicting postoperative recurrence of esophageal cancer.

BACKGROUND: Recently, intestinal bacteria have attracted attention as factors affecting the prognosis of patients with cancer. However, the intestinal microbiome is composed of several hundred types of bacteria, necessitating the development of an analytical method that can allow the use of this information as a highly accurate biomarker. In this study, we investigated whether the preoperative intestinal bacterial profile in patients with esophageal cancer who underwent surgery after preoperative chemotherapy could be used as a biomarker of postoperative recurrence of esophageal cancer. METHODS: We determined the gut microbiome of the patients using 16S rRNA metagenome sequencing, followed by statistical analysis. Simultaneously, we performed a machine learning analysis using a random forest model with hyperparameter tuning and compared the data obtained. RESULTS: Statistical and machine learning analyses revealed two common bacterial genera, Butyricimonas and Actinomyces, which were abundant in cases with recurrent esophageal cancer. Butyricimonas primarily produces butyrate, whereas Actinomyces are oral bacteria whose function in the gut is unknown. CONCLUSION: Our results indicate that Butyricimonas spp. may be a biomarker of postoperative recurrence of esophageal cancer. Although the extent of the involvement of these bacteria in immune regulation remains unknown, future research should investigate their presence in other pathological conditions. Such research could potentially lead to a better understanding of the immunological impact of these bacteria on patients with cancer and their application as biomarkers.

Computational estimation of sediment symbiotic bacterial structures of seagrasses overgrowing downstream of onshore aquaculture.

Coastal seagrass meadows are essential in blue carbon and aquatic ecosystem services. However, this ecosystem has suffered severe eutrophication and destruction due to the expansion of aquaculture. Therefore, methods for the flourishing of seagrass are still being explored. Here, data from 49 public coastal surveys on the distribution of seagrass and seaweed around the onshore aquaculture facilities are revalidated, and an exceptional area where the seagrass Zostera marina thrives was found near the shore downstream of the onshore aquaculture facility. To evaluate the characteristics of the sediment for growing seagrass, physicochemical properties and bacterial ecological evaluations of the sediment were conducted. Evaluation of chemical properties in seagrass sediments confirmed a significant increase in total carbon and a decrease in zinc content. Association analysis and linear discriminant analysis refined bacterial candidates specified in seagrass overgrown- and nonovergrown-sediment. Energy landscape analysis indicated that the symbiotic bacterial groups of seagrass sediment were strongly affected by the distance close to the seagrass-growing aquaculture facility despite their bacterial population appearing to fluctuate seasonally. The bacterial population there showed an apparent decrease in the pathogen candidates belonging to the order Flavobacteriales. Moreover, structure equation modeling and a linear non-Gaussian acyclic model based on the machine learning data estimated an optimal sediment symbiotic bacterial group candidate for seagrass growth as follows: the Lachnospiraceae and Ruminococcaceae families as gut-inhabitant bacteria, Rhodobacteraceae as photosynthetic bacteria, and Desulfobulbaceae as cable bacteria modulating oxygen or nitrate reduction and oxidation of sulfide. These observations confer a novel perspective on the sediment symbiotic bacterial structures critical for blue carbon and low-pathogenic marine ecosystems in aquaculture.

Interpopulation variation of behavioural and morphological traits that affect downstream displacement of the juvenile white-spotted charr Salvelinus leucomaenis.

Downstream displacement, the passive downstream dispersal of riverine organisms, can generate evolutionary pressures that selectively remove susceptible individuals from upstream habitats. These evolutionary pressures may accumulate over time in fish populations situated upstream of a tall check dam that displaced fish are unable to swim over and can be diluted by the homing of displaced individuals in the absence of such barriers. Here, we conducted interpopulation comparisons between above-dam and unrestricted open-stream populations of the juvenile white-spotted charr Salvelinus leucomaenis to test the hypothesis that above-dam juveniles possess more advantageous traits that reduce downstream displacement than open-stream juveniles. We focused on sedentary behaviour and body depth, both of which are known to affect downstream displacement. Interpopulation comparisons revealed that juveniles from above-dam populations were consistently more sedentary than those from open-stream populations. On the other hand, there were no systematic differences in body depth between above-dam and open-stream populations. These results are consistent with the evolution of behaviours in above-dam populations that inhibit downstream displacement. However, several other factors could explain the results obtained and further studies will be needed to confirm the presence of behavioural evolution in our study system.

FGFR2 loss sensitizes MYCN-amplified neuroblastoma CHP134 cells to CHK1 inhibitor-induced apoptosis.

Checkpoint kinase 1 (CHK1) plays a key role in genome surveillance and integrity throughout the cell cycle. Selective inhibitors of CHK1 (CHK1i) are undergoing clinical evaluation for various human malignancies, including neuroblastoma. In this study, one CHK1i-sensitive neuroblastoma cell line, CHP134, was investigated, which characteristically carries MYCN amplification and a chromosome deletion within the 10q region. Among several cancer-related genes in the chromosome 10q region, mRNA expression of fibroblast growth factor receptor 2 (FGFR2) was altered in CHP134 cells and associated with an unfavorable prognosis of patients with neuroblastoma. Induced expression of FGFR2 in CHP134 cells reactivated downstream MEK/ERK signaling and resulted in cells resistant to CHK1i-mediated cell growth inhibition. Consistently, the MEK1/2 inhibitor, trametinib, potentiated CHK1 inhibitor-mediated cell death in these cells. These results suggested that FGFR2 loss might be prone to highly effective CHK1i treatment. In conclusion, extreme cellular dependency of ERK activation may imply a possible application for the MEK1/2 inhibitor, either as a single inhibitor or in combination with CHK1i in MYCN-amplified neuroblastomas.

Parametric downconversion via vibronic transition.

This Letter presents the first, to the best of our knowledge, demonstration of noncritically birefringent-phase-matched parametric downconversion, which is associated with stimulated emission via vibronic transition in a laser gain medium. The so-called self-difference frequency generation is realized along the a-axis of a Cr:CdSe single crystal pumped by a Tm:YAG laser pulse at 2.013 µm, directly producing an infrared spectrum centered at 9 µm with the maximized effective nonlinearity. The light source, which benefits from the broad vibronic spectroscopic properties together with the wide transparency range of the host material, is expected to generate noncritically phase-matched, mid-infrared spectra beyond 20 µm along with birefringence engineering in the solid solution Cr:CdSxSe1-x.

The Sympathetic Nervous System Contributes to the Establishment of Pre-Metastatic Pulmonary Microenvironments.

Emerging evidence suggests that neural activity contributes to tumor initiation and its acquisition of metastatic properties. More specifically, it has been reported that the sympathetic nervous system regulates tumor angiogenesis, tumor growth, and metastasis. The function of the sympathetic nervous system in primary tumors has been gradually elucidated. However, its functions in pre-metastatic environments and/or the preparation of metastatic environments far from the primary sites are still unknown. To investigate the role of the sympathetic nervous system in pre-metastatic environments, we performed chemical sympathectomy using 6-OHDA in mice and observed a decrease in lung metastasis by attenuating the recruitment of myeloid-derived suppressor cells. Furthermore, we note that neuro-immune cell interactions could be observed in tumor-bearing mouse lungs in conjunction with the decreased expression of Sema3A. These data indicate that the sympathetic nervous system contributes to the preparation of pre-metastatic microenvironments in the lungs, which are mediated by neuro-immune cell interactions.

A high number of PD-L1+ CD14+ monocytes in peripheral blood is correlated with shorter survival in patients receiving immune checkpoint inhibitors.

PURPOSE: Targeting of anti-programmed cell death protein-1 (PD-1) and anti-programmed death-ligand 1 (PD-L1) is a standard therapeutic strategy for various cancers. The aim of the present study was to investigate the prognostic effect of pretreatment PD-L1 expression levels in peripheral blood mononuclear cell (PBMC) subsets for patients with several cancer types receiving anti-PD-1 blockade therapies. PATIENTS AND METHODS: Thirty-two patients undergoing anti-PD-L1 blockade therapy, including 15 with non-small cell lung cancer, 14 with gastric cancer, 1 with melanoma, 1 with parotid cancer, and 1 with bladder cancer, were recruited for the present study. PD-L1 expression levels in CD3+, CD4+, CD8+, CD45RA+ and CCR7+ T cells; CD20+ B cells; CD14+ and CD16+ monocytes were measured via flow cytometry before treatment. The percentages of PD-L1+ cells in respective PBMC subsets were compared with respect to different clinicopathological conditions and the association with overall survival (OS) was assessed. RESULTS: The percentages of PD-L1+ with CD3+, CD4+ and CD8+ T cells including naïve and memory T cell subsets, or CD20+ B cells during pretreatment were not markedly correlated with the OS of patients (p > 0.05); however, the percentage of the PD-L1+ CD14+ monocyte subset was significantly correlated with OS (p = 0.0426). CONCLUSION: Increase in pretreatment expression levels of PD-L1 on CD14+ monocytes is associated with the OS of patients treated with immune checkpoint inhibitors. Further evaluation of large sample size and each specific cancer type might clarify the predictive role of PBMC in patients.

Analysis of ADAM12-Mediated Ephrin-A1 Cleavage and Its Biological Functions.

Accumulating evidence indicates that an elevated ephrin-A1 expression is positively correlated with a worse prognosis in some cancers such as colon and liver cancer. The detailed mechanism of an elevated ephrin-A1 expression in a worse prognosis still remains to be fully elucidated. We previously reported that ADAM12-cleaved ephrin-A1 enhanced lung vascular permeability and thereby induced lung metastasis. However, it is still unclear whether or not cleaved forms of ephrin-A1 are derived from primary tumors and have biological activities. We identified the ADAM12-mediated cleavage site of ephrin-A1 by a Matrix-assisted laser desorption ionization mass spectrometry and checked levels of ephrin-A1 in the serum and the urine derived from the primary tumors by using a mouse model. We found elevated levels of tumor-derived ephrin-A1 in the serum and the urine in the tumor-bearing mice. Moreover, inhibition of ADAM-mediated cleavage of ephrin-A1 or antagonization of the EphA receptors resulted in a significant reduction of lung metastasis. The results suggest that tumor-derived ephrin-A1 is not only a potential biomarker to predict lung metastasis from the primary tumor highly expressing ephrin-A1 but also a therapeutic target of lung metastasis.

Impulse measurement of laser induced ablation in a vacuum.

An impulse measurement system based on a simple pendulum is newly developed. The system has a resolution of 10-7 Ns for ablation events induced by a single laser at a pulse rate of 2 Hz or less. For ablation events at 10 Hz and above, the system can record the impulse as an average force. The impulse generated by a Nd:YAG pulse laser irradiating a 7075 aluminum alloy is investigated in vacuum. The impulse arises at 3 J/cm2 and the momentum coupling factor, Cm, plateaus at approximately 20 µNs/J over a range of 5 to 50 J/cm2 without producing a plasma shielding effect. Cm is characterized by only fluence independent of pulse width in the range of 10 to 20 ns. This result indicates that it should be feasible to deorbit a 150 kg abandoned satellite at an altitude of 1200 km using a chaser satellite equipped with a 100 W laser.

CAT1/SLC7A1 acts as a cellular receptor for bovine leukemia virus infection.

Bovine leukemia virus (BLV) is the causative agent of enzootic bovine leukosis, the most common neoplastic disease of cattle, which is closely related to human T-cell leukemia viruses. BLV has spread worldwide and causes a serious problem for the cattle industry. The cellular receptor specifically binds with viral envelope glycoprotein (Env), and this attachment mediates cell fusion to lead virus entry. BLV Env reportedly binds to cationic amino acid transporter 1 (CAT1)/solute carrier family 7 member 1 (SLC7A1), but whether the CAT1/SLC7A1 is an actual receptor for BLV remains unknown. Here, we showed that CAT1 functioned as an infection receptor, interacting with BLV particles. Cells expressing undetectable CAT1 levels were resistant to BLV infection but became highly susceptible upon CAT1 overexpression. CAT1 exhibited specific binding to BLV particles on the cell surface and colocalized with the Env in endomembrane compartments and membrane. Knockdown of CAT1 in permissive cells significantly reduced binding to BLV particles and BLV infection. Expression of CAT1 from various species demonstrated no species specificity for BLV infection, implicating CAT1 as a functional BLV receptor responsible for its broad host range. These findings provide insights for BLV infection and for developing new strategies for treating BLV and preventing its spread.-Bai, L., Sato, H., Kubo, Y., Wada, S., Aida, Y. CAT1/SLC7A1 acts as a cellular receptor for bovine leukemia virus infection.

[Current Status of Biomarkers in the Use of Immune Checkpoint Inhibitors].

Cancer immunotherapy has become a central treatment of cancer with the advent of immune checkpoint inhibitors, and it has caused a paradigm shift in the treatment of cancer. On the other hand, it has been found that only about 10 to 30% of treated patients can obtain the benefit in most cancer types. At present, more than 2,000 clinical trials of combination therapies centering on immune checkpoint inhibitors are being conducted in the hope of further improving the therapeutic effect. A number of combination therapies will be available in the clinic, and a wide range of options will be available in the future. Since it is predicted that direct comparison data will not necessarily be obtained in future treatment options, treatment decisions based on the mechanism and patient status are even more strongly demanded. In addition, identification of biomarkers that can predict therapeutic effects is expected. This article described the current status and prospects of biomarker development in the use of immune checkpoint inhibitors.

Heat shock protein 105 peptide vaccine could induce antitumor immune reactions in a phase I clinical trial.

Heat shock protein 105 (HSP105) is overexpressed in many cancers, including colorectal cancer (CRC) and esophageal cancer (EC). We carried out a phase I clinical trial of HLA-A24- and HLA-A2-restricted HSP105 peptide vaccines in patients with CRC or EC. In this additional study of the trial, we examined the immunological efficacy of the novel vaccine. Thirty patients with advanced CRC or EC underwent HSP105 peptide vaccination. Immunological responses were evaluated by ex vivo and in vitro γ-interferon enzyme-linked immunospot assays and their correlation with patients' prognosis was analyzed. The HSP105 peptide vaccines induced peptide-specific CTLs in 15 of 30 patients. Among HLA-A24 patients (n = 15), 7 showed induction of CTLs only ex vivo, whereas among HLA-A2 patients (n = 15), 4 showed the induction ex vivo and 6 in vitro. Heat shock protein 105-specific CTL induction correlated with suppression of cancer progression and was revealed as a potential predictive biomarker for progression-free survival (P = .008; hazard ratio = 3.03; 95% confidence interval, 1.34-6.85) and overall survival (P = .025; hazard ratio = 2.72; 95% confidence interval, 1.13-6.52). Production of cytokines by HSP105 peptide-specific CTLs was observed at the injection sites (skin) and tumor tissues, suggesting that HSP105-specific CTLs not only accumulated at vaccination sites but also infiltrated tumors. Furthermore, we established 2 HSP105 peptide-specific CTL clones, which showed HSP105-specific cytokine secretion and cytotoxicity. Our results suggest that the HSP105 peptide vaccine could induce immunological effects in cancer patients and improve their prognosis.

Immunohistological analysis of pancreatic carcinoma after vaccination with survivin 2B peptide: Analysis of an autopsy series.

Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of cancer by providing new options in addition to existing therapies. However, peptide vaccination therapies still represent an attractive approach, because of the antigen specificity. We identified survivin 2B peptide (SVN-2B), a 9-mer antigenic peptide encoded by survivin, and an SVN-2B peptide vaccine-based phase II randomized clinical trial targeting unresectable and refractory pancreatic carcinoma was undertaken. The SVN-2B peptide vaccine did not have any statistically significant clinical benefits in that study. Therefore, we undertook an autopsy study to analyze the immune status of the pancreatic cancer lesions at the histological level. Autopsies were carried out in 13 patients who had died of pancreatic cancer, including 7 who had received SVN-2B peptide vaccination and 6 who had not, as negative controls. The expression of immune-related molecules was analyzed by immunohistochemical staining. Cytotoxic T lymphocytes were analyzed by tetramer staining and enzyme-linked immunospot assay. Histological analysis revealed dense infiltration of CD8+ T cells in some lesions in patients who had received the SVN-2B peptide vaccine. A high rate of programmed cell death ligand 1 expression in cancer cells was observed in these cases, indicating that CTLs were induced by SVN-2B peptide vaccination and had infiltrated the lesions. The lack of a significant antitumor effect was most likely attributable to the expression of immune checkpoint molecules. These findings suggest that the combination of a tumor-specific peptide vaccine and an ICI might be a promising approach to the treatment of pancreatic carcinoma in the future.

Randomized phase II trial of survivin 2B peptide vaccination for patients with HLA-A24-positive pancreatic adenocarcinoma.

The prognosis of advanced pancreatic adenocarcinoma is still extremely poor. This study sought to determine the efficacy of, and immunological response to, peptide vaccination therapy in patients with this disease. In this multicenter randomized phase II study, patients with advanced pancreatic adenocarcinoma after gemcitabine and/or tegafur/gimeracil/oteracil were randomly assigned to 3 groups that each received a 2-step treatment course. In Step 1, the groups received treatments of: (i) survivin 2B peptide (SVN-2B) plus interferon-ß (IFNß); (ii) SVN-2B only; or (iii) placebo until the patients show progression. In Step 2, all patients who consented to participate received 4 treatments with SVN-2B plus IFNß. The primary endpoint was progression-free survival (PFS) after initiation of Step 1 treatment. Secondary endpoints included immunological effects assessed by analysis of PBMCs after Step 1. Eighty-three patients were randomly assigned to receive SVN-2B plus IFNß (n = 30), SVN-2B (n = 34), or placebo (n = 19). No significant improvement in PFS was observed. Survivin 2B-specific CTLs were found to be increased in the SVN-2B plus IFNß group by tetramer assay. Among patients who participated in Step 2, those who had received SVN-2B plus IFNß in Step 1 showed better overall survival compared with those who had received placebo in Step 1. Patients vaccinated with SVN-2B plus IFNß did not have improved PFS, but showed significant immunological reaction after vaccination. Subgroup analysis suggested that a longer SVN-2B plus IFNß vaccination protocol might confer survival benefit. (Clinical trial registration number: UMIN 000012146).

Programmable deep-UV laser platform for inspection and metrology.

This Letter reports on a high-power, narrow-linewidth deep-UV laser platform built upon a frequency-quintupled, Yb-fiber master-oscillator and power-amplifier system. The source, emitting at a pulse repetition rate of 120 MHz with a linewidth of 90 GHz and beam quality of MX/Y2∼2.1/1.5, has been stably maintained over two weeks by successively changing positions and temperatures of nonlinear crystals in parallel, while outputting a 0.5-W average power at 213 nm.

Mapping of CD4+ T-cell epitopes in bovine leukemia virus from five cattle with differential susceptibilities to bovine leukemia virus disease progression.

BACKGROUND: Bovine leukemia virus (BLV), which is closely related to human T-cell leukemia virus, is the etiological agent of enzootic bovine leukosis, a disease characterized by a highly prolonged course involving persistent lymphocytosis and B-cell lymphoma. The bovine major histocompatibility complex class II region plays a key role in the subclinical progression of BLV infection. In this study, we aimed to evaluate the roles of CD4+ T-cell epitopes in disease progression in cattle. METHODS: We examined five Japanese Black cattle, including three disease-susceptible animals, one disease-resistant animal, and one normal animal, classified according to genotyping of bovine leukocyte antigen (BoLA)-DRB3 and BoLA-DQA1 alleles using polymerase chain reaction sequence-based typing methods. All cattle were inoculated with BLV-infected blood collected from BLV experimentally infected cattle and then subjected to CD4+ T-cell epitope mapping by cell proliferation assays. RESULTS: Five Japanese Black cattle were successfully infected with BLV, and CD4+ T-cell epitope mapping was then conducted. Disease-resistant and normal cattle showed low and moderate proviral loads and harbored six or five types of CD4+ T-cell epitopes, respectively. In contrast, the one of three disease-susceptible cattle with the highest proviral load did not harbor CD4+ T-cell epitopes, and two of three other cattle with high proviral loads each had only one epitope. Thus, the CD4+ T-cell epitope repertoire was less frequent in disease-susceptible cattle than in other cattle. CONCLUSION: Although only a few cattle were included in this study, our results showed that CD4+ T-cell epitopes may be associated with BoLA-DRB3-DQA1 haplotypes, which conferred differential susceptibilities to BLV proviral loads. These CD4+ T-cell epitopes could be useful for the design of anti-BLV vaccines targeting disease-susceptible Japanese Black cattle. Further studies of CD4+ T-cell epitopes in other breeds and using larger numbers of cattle with differential susceptibilities are required to confirm these findings.

Dynamic nuclear polarization with photo-excited triplet electrons using 6,13-diphenylpentacene.

Dynamic nuclear polarization with photo-excited triplet electrons (Triplet-DNP) is demonstrated using 6,13-diphenylpentacene (DPPentacene). DPPentacene is soluble in various organic solvents, while pentacene, which is used in most of the triplet-DNP experiments, has limited solubility. An enhancement factor of 81 is obtained for 1H spins in the glass of ethanol-d6 : water = 80 : 20 (w/w) doped with 0.1 mM DPPentacene at 90 K in 0.67 T.

Co-Inhibition of the DNA Damage Response and CHK1 Enhances Apoptosis of Neuroblastoma Cells.

Checkpoint kinase 1 (CHK1) is a central mediator of the DNA damage response (DDR) at the S and G2/M cell cycle checkpoints, and plays a crucial role in preserving genomic integrity. CHK1 overexpression is thought to contribute to cancer aggressiveness, and several selective inhibitors of this kinase are in clinical development for various cancers, including neuroblastoma (NB). Here, we examined the sensitivity of MYCN-amplified NB cell lines to the CHK1 inhibitor PF-477736 and explored mechanisms to increase its efficacy. PF-477736 treatment of two sensitive NB cell lines, SMS-SAN and CHP134, increased the expression of two pro-apoptotic proteins, BAX and PUMA, providing a mechanism for the effect of the CHK1 inhibitor. In contrast, in NB-39-nu and SK-N-BE cell lines, PF-477736 induced DNA double-strand breaks and activated the ataxia telangiectasia mutated serine/threonine kinase (ATM)-p53-p21 axis of the DDR pathway, which rendered the cells relatively insensitive to the antiproliferative effects of the CHK1 inhibitor. Interestingly, combined treatment with PF-477736 and the ATM inhibitor Ku55933 overcame the insensitivity of NB-39-nu and SK-N-BE cells to CHK1 inhibition and induced mitotic cell death. Similarly, co-treatment with PF-477736 and NU7441, a pharmacological inhibitor of DNA-PK, which is also essential for the DDR pathway, rendered the cells sensitive to CHK1 inhibition. Taken together, our results suggest that synthetic lethality between inhibitors of CHK1 and the DDR drives G2/M checkpoint abrogation and could be a novel potential therapeutic strategy for NB.

Dimethyl fumarate inhibits osteoclasts via attenuation of reactive oxygen species signalling by augmented antioxidation.

Bone destructive diseases are common worldwide and are caused by dysregulation of osteoclast formation and activation. During osteoclastogenesis, reactive oxygen species (ROS) play a role in the intracellular signalling triggered by receptor activator of nuclear factor-κB ligand (RANKL) stimulation. Previously, we demonstrated that induction of antioxidant enzymes by Nrf2 activation using Nrf2-gene transfer, an ETGE-peptide or polyphenols, successfully ameliorated RANKL-dependent osteoclastogenesis. Dimethyl fumarate (DMF) has been shown to activate Nrf2 signalling and has been lately used in clinical trials for neurodegenerative diseases. In this study, we hypothesized that Nrf2 activation by DMF would inhibit osteoclastogenesis and bone destruction via attenuation of intracellular ROS signalling through antioxidant mechanisms. RAW 264.7 cells were used as osteoclast progenitor cells. We found that DMF induced Nrf2 translocation to the nucleus, augmented Nrf2 promoter-luciferase reporter activity and increased antioxidant enzyme expression. Using flow cytometry, we found that DMF attenuated RANKL-mediated intracellular ROS generation, which resulted in the inhibition of RANKL-mediated osteoclastogenesis. Local DMF injection into the calvaria of male BALB/c mice resulted in attenuated bone destruction in lipopolysaccharide-treated mice. In conclusion, we demonstrated in a preclinical setting that DMF inhibited RANKL-mediated osteoclastogenesis and bone destruction via induction of Nrf2-mediated transcription of antioxidant genes and consequent decrease in intracellular ROS levels. Our results suggest that DMF may be a promising inhibitor of bone destruction in diseases like periodontitis, rheumatoid arthritis and osteoporosis.