Tumor necrosis factor-α (TNF), a proinflammatory cytokine, is critical to the pathogenesis of various inflammatory diseases. There are two subtypes of receptors for TNF, namely type I TNF receptor (TNFR1) and type II TNF receptor (TNFR2). Previous studies using animal models of diseases have demonstrated the predominant role of TNFR1 in the pathogenesis of inflammation. It has recently been proposed that TNFR2 is associated with anti-inflammatory function. This intriguing function of TNFR2 has implications from an immunological and pharmacological perspective. However, the mechanism of the TNFR2-mediated anti-inflammatory effect is not fully understood. In this context, we attempted to elucidate the TNFR2-mediated anti-inflammatory effect and other unknown biological functions of TNFR2 by utilizing our protein engineering technology to generate functional mutant cytokines. Our findings reveal the following. (1) TNFR2 is expressed on regulatory T cells (Tregs) but not conventional T cells (Tconvs) and TNFR2-mediated signals promote proliferation and activation of Tregs. (2) The crystal structure of TNF/TNFR2 complex was solved, which suggests a possible signal initiation mechanism via TNF/TNFR2 cluster formation on the cellular membrane. (3) A novel TNFR2-mediated signal molecule, aminopeptidase P3 (APP3/XPNPEP3), was identified that interacts with TNFR2 as an intracellular adaptor protein. APP3 is required for c-Jun N-terminal kinase (JNK) phosphorylation, the downstream molecule of TNFR2 signal transduction. These results are key to understanding the mechanism of immune regulation and will assist in the identification of immunomodulatory drugs targeting the TNFR2 signaling cascade as well as the function of Tregs.
Infectious disease chemotherapy pharmacists should evaluate the appropriate usage of antimicrobial agents within the hospital, support in-patient pharmacists in treating infections, and appropriately use antimicrobial agents throughout the infection treatment course. Hospital pharmacists are required to strive to prevent adverse events and support the appropriateness of antimicrobial use to cure infectious diseases. Our hospital's antimicrobial stewardship team provides support and information on the proper use of antimicrobial agents in collaboration with in-patient pharmacists. Among other things, thrombocytopenia in linezolid therapy can often be an obstacle to treatment. We conducted clinical and basic research on thrombocytopenia, the major adverse event associated with linezolid. We first conducted a retrospective study investigating renal dysfunction and thrombocytopenia associated with vancomycin and linezolid treatments. Renal dysfunction occurred more frequently in patients receiving vancomycin than those receiving linezolid (p=0.032). In contrast, thrombocytopenia occurred more frequently in patients treated with linezolid than those treated with vancomycin (p<0.001). A significantly higher rate of thrombocytopenia was observed in patients with linezolid treatment durations >7.5 days. Secondly, we examined whether the linezolid cytotoxicity to eukaryotic cells was associated with mitochondrial dysfunction and apoptosis-like cell death in U937 human leukemic monocyte lymphoma cells. Apoptosis-like cell death was clearly observed in cells incubated with linezolid in concentration- and duration-dependent manners. Linezolid cytotoxicity was relieved by superoxide dismutase-1 knockdown in U937 cells. These results suggest that mitochondrial damage could be linked to the induction of apoptosis in linezolid-treated U937 cells.
Although molecular targeted drugs are significantly effective in many types of cancer treatment, almost all patients suffer from drug resistance. For instance, non-small cell lung cancer (NSCLC) patients with epidermal growth factor receptor (EGFR) mutation invariably develop resistance to EGFR tyrosine kinase inhibitors (EGFR-TKIs) and melanoma patients with BRAF mutation develop resistance to BRAF inhibitors. Mechanistically, genetic and irreversible resistance mechanisms have been studied for more than a decade, while non-mutational and reversible resistance mechanisms are yet to be clearly understood. Since drug tolerant persisters (DTPs), which emerge at the beginning of the drug treatment, have been reported in 2010, several non-mutational tolerance mechanisms have been reported by various researchers. Furthermore, with the advancement in single cell sequencing technology, increasing attention has been drawn towards the investigation of the heterogeneous characteristics of drug tolerant cell populations. Here, we describe the recent advances in non-mutational drug tolerant mechanisms toward the molecular targeted drugs. In our study, we tried to elucidate the unconventional resistance mechanisms by utilizing newly approved EGFR-TKI, dacomitinib. Our established drug resistant cells did not gain new mutation in EGFR even after long time exposure to the drug. In addition, the drug resistance vanished when resistant cells were implanted in mice, which indicates that mechanisms conferring drug sensitivity might be host-dependent. Thus, our study may provide a new insight into non-mutational drug tolerant mechanisms.
Tissue-resident memory T cells are a highly abundant, non-blood circulating subset of memory T cells. These appear to be the most protective population of memory T cells at barrier surfaces. Long-term retention and survival of tissue-resident memory CD8+ T cells (Trm) is determined by tissue-derived signals, such as keratinocyte-mediated activation of transforming growth factor β (TGFβ) in the epidermis. We found that T cell clones compete for limited amounts of active TGFβ and pre-existing Trm could be replaced with newly recruited effector T cells in the epidermis. On the other hand, when effector T cells transition into Trm, the presence of cutaneous cognate antigen increases the fitness of individual Trm clones in the epidermal niche. Thus, antigen-specific Trm are more efficiently retained than bystander Trm that have not encountered cognate antigens when they compete with newly recruited effector T cells for limited active TGFβ. Therefore, competition between T cells for active TGFβ represents a selective pressure that promotes the accumulation of antigen-specific Trm cells in the epidermal niche. Furthermore, our model implies that the epidermis offers a finite niche for maintaining Trm. Although the epidermal niche of Trm cannot represent the capacity of T cell-mediated immune memory in our body, these findings might suggest a challenge for the accommodation of memory T cells specific to multiple pathogens throughout a lifetime.
Nonalcoholic fatty liver disease (NAFLD), including nonalcoholic fatty liver (NAFL) and a more advanced condition with inflammation/fibrosis, nonalcoholic steatohepatitis (NASH), is emerging as one of the most prevalent chronic diseases associated with the worldwide expansion of the obese population; however, there are currently only symptomatic therapy but no cure. Among multiple candidate drugs that have been developed and tried in clinical trials against NAFLD/NASH, peroxisome proliferator-activated receptor (PPAR) dual/pan agonists continue to be the most expected ones. This review summarizes the current condition of several PPAR agonists that were and are in clinical trials against NAFLD/NASH. In addition, we recently expanded structural information about PPARα/δ/γ-ligand interactions by X-ray crystallography and executed comparative functional analyses of PPARα/δ/γ activation by those ligands; based on those knowledge, we propose the reevaluation or repositioning of currently approved PPAR agonists, saroglitazar, bezafibrate, and pemafibrate, for the treatment of NAFLD/NASH.
Peroxisome proliferator-activated receptor γ (PPARγ) is a member of the nuclear receptor superfamily, which plays an important role in glucose and lipid metabolism as well as inflammation. The transcriptional activity of PPARγ is regulated by the binding of its ligand and the accompanied conformational change followed by the recruitment of cofactors. The ligand-binding pocket (LBP) of PPARγ comprises multiple sub-pockets and includes a large, Y-shaped cavity. In some cases, more than two ligands simultaneously occupy the LBP and cooperatively activate PPARγ transcription. Inspired by this peculiar character, the author proposed a strategy to create new PPARγ ligands in two steps: first, identifying a combination of ligands that cooperatively activate PPARγ, and second, designing and synthesizing their hybrid structure. Cooperative activation can be detected by a conventional cell-based assay using a reporter gene, which may provide advantages over the existing fragment-based drug discovery approach. Using this strategy, a plant-derived cinnamic acid derivative was found to synergistically activate PPARγ in combination with GW9662, an irreversible antagonist. The designed hybrid structure was synthesized and found to behave as a covalent agonist, which partially activates PPARγ transcription. Structure-activity studies revealed the importance of proximity and orientation in the linkage of the two units. The strategy discussed in this article may contribute to the development of a highly potent PPARγ agonist.
Peroxisome proliferator-activated receptors (PPARs) are transcription factors that are activated by endogenous fatty acids and synthetic compounds as ligands. We have been developing new phenylpropanoic acid derivatives based on structure-activity relationship studies that could reduce the side effects of existing clinical drugs. As a result, we have obtained many partial agonists that exhibit a moderate transcriptional activity while maintaining high specificity towards the receptors. However, because most of them are poorly soluble, protein-ligand interaction information has not yet been obtained by X-ray crystallography, which is essential for structure-activity relationship studies. In this paper, we report our ongoing crystallization experiments, which are aimed to develope a crystallization method for PPAR LBDs in solid-phase hydrogels that enables high-throughput protein-ligand complex crystal structure determination, using poorly soluble ligands.
Nuclear receptors are ligand-dependent transcription factors that act as signal transducers by binding to and regulating the transcription of target DNA (genomic action). In recent years, nuclear receptors have also been found to exhibit a direct action on target proteins without affecting their transcription (non-genomic action). Independent complexes are expected to distinguish these two nuclear receptor actions. In this paper, I report the non-genomic action of peroxisome proliferator-activated receptor γ (PPARγ) agonists and propose a strategy for treatment of renal fibrotic diseases by PPARγ agonists with an emphasis on non-genomic actions.
Green tea components, such as catechins have been reported to provide several benefits including anti-oxidative, anti-viral/bacterial, and anti-inflammatory effects in vitro and in vivo. Catechins effectively inhibited the adsorption and replication of the influenza virus. Additionally, green tea contains theanine and vitamin C, which enhance the immunity against viral/bacterial infections. Based on these, green tea is hypothesized to have potential benefits in the prevention of influenza and other respiratory tract infections in the clinical setting. However, its specific effects in patients remain unclear. To determine the clinical significance of green tea in the prevention of respiratory tract infections, we conducted an observational study and eight interventional studies. Based on the results of three studies, consuming or gargling green tea or its components significantly aided in the prevention of influenza. Meanwhile, one study showed that green tea successfully prevented common colds. Catechin inhalation was also reported to decrease the bacterial load of methicillin-resistant Staphylococcus aureus in the sputum. Although the anti-viral/anti-bacterial effects of green tea components have been demonstrated in experimental studies, the clinical evidence remains limited. Further studies are required to confirm the clinical efficacy of green tea and its components in preventing respiratory tract infections.
Green tea components, such as catechins are reported to have anti- viral/bacterial and anti-inflammatory effects in experimental studies. This review demonstrated the clinical significance of green tea focusing on the respiratory tract infections based on their clinical studies. Consuming or gargling green tea or its components significantly aided in the prevention of influenza. Catechin inhalation also decreased the bacterial load of methicillin-resistant Staphylococcus aureus. Although the clinical evidence remains limited, further studies are expected to clarify the clinical efficacy.
Development of a formulary is an important issue to achieve rational use of medicines in each local medical area in Japan. The purpose of developing the formulary is to secure the access for safe, effective, and affordable medications based on evidence for patients, families, healthcare professionals as well as for general publics. The economic aspect plays an important role for the establishment of the formulary, while the word “economic” is often misread as simple “cost reduction”, which only aims to generic/biosimilar substitutions. Both health outcomes and costs, should be taken into account under the true “health economic analysis”, or the cost-effectiveness analyses (CEA). Information provided via the CEA could be useful for establishment of the formulary. Moreover, various value assessment of medicines in health technology assessments (HTA) field beyond the current approach of safety, effectiveness, and economics evaluations should be considered. In this review, we discuss comprehensive assessment of various value components of medicines to establish the most suitable formulary which would contribute to whole society, as well as healthcare facilities/patients.
Although the dosage of oral antibiotics (OA) for the mandibular third molar extraction (MTME) varies among the administration periods according to the current guideline, our previous reports suggested that it might be possible to further shorten the administration period without increasing the incidence of surgical site infection (SSI). In the present study, we retrospectively evaluated the relationship between the incidence of SSI and the administration period of OA in patients who underwent the MTME in our hospital. This retrospective cohort study included 348 patients who underwent the MTME in our dental outpatient clinic from June 2020 to March 2022. The administrated antibiotic was amoxicillin (AMPC) in all patients. Patients were divided into two groups based on the administration period of AMPC single and three times before the surgery. The following information was collected: (1) patient factors (age, gender, body mass index, diagnosis, mandibular third molar status); (2) surgical factors (operation time, presence/absence of wound closure, presence/absence of hemostat, experience of surgeons); (3) relationship between administration period of OA and SSI occurrence; and (4) details of SSI. There were 217 cases in the single group and 131 cases in the three times group. The incidence of SSI was 1.1% (4/348), with 1.4% (3/217) in the single group and 0.8% (1/131) in the three times group; there was no significant difference between the two groups. Our result suggests that single administration of AMPC before the MTME would be sufficient for the prevention of SSI in Japanese patients without risk factors.
Decisions concerning approval of human papillomavirus (HPV) vaccines and their use are based on expert evaluation of the vaccines. However, the quantitative differences between vaccine benefits and risks are difficult for non-experts to understand. In this study, we developed a new method to calculate the benefits and risks of the HPV vaccines using disability-adjusted life year (DALY) as the mono-scaled weight for various benefits and risks relevant to the vaccines. We evaluated benefits as a gain of DALY values for cervical cancer and risks as the loss of DALY values for various adverse events by the vaccination. To calculate the loss of DALY values, we integrated all adverse events in the International Classification of Diseases chapters. The novel method reflected the men-women ratio of this epidemiological disease to a certain extent. Among the vaccinated women, 111372 and 477190 received a bivalent and quadrivalent vaccine, respectively. The DALY rate of cervical cancer was 148.7. The calculated benefit for the bivalent and quadrivalent vaccines was 149.1 and 638.8, respectively, and set as the theoretical maximum. The risk was calculated as 129.3 and 49.6 in the bivalent and quadrivalent vaccines, respectively. Since HPV vaccines prevent several other cancers, the benefit of the vaccination extends beyond the risk according to this new method.
Patients with pancreatic cancer (PC) often suffer from refractory ascites associated with peritoneal metastasis. This severely impairs activities of daily living and leads to an unfavorable prognosis. Cell-free and concentrated ascites reinfusion therapy (CART) has attracted attention as a promising therapy for relieving the symptoms of malignant ascites. Accumulating evidence suggests that malignant ascites contains a variety of soluble factors, such as cytokines, that can be beneficial or detrimental in the prognosis of patients with refractory ascites. However, the expression profiles of these cytokines in the ascites before and after CART remain unknown. In this study, we used a comprehensive cytokine array to measure the expression levels of 102 cytokines in ascites derived from patients with PC before and after CART. The assay results revealed that the concentrations of several cytokines exacerbating tumor angiogenesis and tumor-suppressive interferon-gamma (IFN-γ) and interleukin-12 (IL-12) were higher in ascites after CART than before CART. Interestingly, growth of KP-2 human PC cells following exposure to ascites after CART decreased considerably compared to that before CART. Concomitant treatment of neutralizing antibodies against IFN-γ or IL-12 with ascites after CART restored the growth of KP-2 cells to the control level. These findings indicate that IFN-γ and IL-12 in ascites after CART may contribute to the inhibited growth of PC cells, highlighting their potential as biomarkers for assessing the clinical efficacy of CART procedures in patients with PC.