論文

• Neural signaling in immunology: the gateway reflex.
  Rie Hasebe, Hiroki Tanaka, Takeshi Yamasaki, Kaoru Murakami, Masaaki Murakami
  International immunology, 37, 7, 369, 377, 2025年06月17日, ［国際誌］
  英語, 研究論文（学術雑誌）, Neural signaling regulates various reactions in our body including immune responses. Neuromodulation of this signaling using artificial neural activation and/or suppression is a potential treatment for diseases and disorders. We here review neural signaling regulating the immune system, with a special focus on the gateway reflex. The gateway reflex is a novel neuro-immune crosstalk mechanism that regulates tissue-specific inflammatory diseases. We have discovered six gateway reflexes so far; all are induced by environmental or artificial stimulations including gravity, electrical stimulation, pain sensation, stress, light, and inflammation in joints. In the presence of increased autoreactive T cells in the blood, such stimulation activates specific neural signaling to release noradrenaline (NA) from the nerve endings at specific blood vessels in the central nervous system. NA activates the interleukin-6 (IL-6) amplifier, which leads to the hyper-activation of nuclear factor-kappa B (NF-κB) in non-immune cells, resulting in the formation of a gateway. This gateway allows autoreactive T cells and other immune cells to accumulate in the target tissue to induce inflammatory diseases. In gateway reflexes induced by stress or remote inflammation, adenosine triphosphate (ATP) secreted from inflammation sites activates specific neural pathways, resulting in organ dysfunction and inflammation in other tissues, suggesting that the gateway reflex regulates tissue-specific inflammatory diseases by bidirectional crosstalk between the neural and immune systems. We also discuss other cases of neural signaling including the inflammatory reflex.
• GGT1 is a SNP eQTL gene involved in STAT3 activation and associated with the development of Post-ERCP pancreatitis.
  Ryutaro Furukawa, Masaki Kuwatani, Jing-Jing Jiang, Yuki Tanaka, Rie Hasebe, Kaoru Murakami, Kumiko Tanaka, Noriyuki Hirata, Izuru Ohki, Ikuko Takahashi, Takeshi Yamasaki, Yuta Shinohara, Shunichiro Nozawa, Shintaro Hojyo, Shimpei I Kubota, Shigeru Hashimoto, Satoshi Hirano, Naoya Sakamoto, Masaaki Murakami
  Scientific reports, 14, 1, 12224, 12224, 2024年05月28日, ［国際誌］
  英語, 研究論文（学術雑誌）, Post-ERCP pancreatitis (PEP) is an acute pancreatitis caused by endoscopic-retrograde-cholangiopancreatography (ERCP). About 10% of patients develop PEP after ERCP. Here we show that gamma-glutamyltransferase 1 (GGT1)-SNP rs5751901 is an eQTL in pancreatic cells associated with PEP and a positive regulator of the IL-6 amplifier. More PEP patients had the GGT1 SNP rs5751901 risk allele (C) than that of non-PEP patients at Hokkaido University Hospital. Additionally, GGT1 expression and IL-6 amplifier activation were increased in PEP pancreas samples with the risk allele. A mechanistic analysis showed that IL-6-mediated STAT3 nuclear translocation and STAT3 phosphorylation were suppressed in GGT1-deficient cells. Furthermore, GGT1 directly associated with gp130, the signal-transducer of IL-6. Importantly, GGT1-deficiency suppressed inflammation development in a STAT3/NF-κB-dependent disease model. Thus, the risk allele of GGT1-SNP rs5751901 is involved in the pathogenesis of PEP via IL-6 amplifier activation. Therefore, the GGT1-STAT3 axis in pancreas may be a prognosis marker and therapeutic target for PEP.
• DDX6 is involved in the pathogenesis of inflammatory diseases via NF-κB activation.
  Seiichiro Naito, Hiroki Tanaka, Jing-Jing Jiang, Masato Tarumi, Ari Hashimoto, Yuki Tanaka, Kaoru Murakami, Shimpei I Kubota, Shintaro Hojyo, Shigeru Hashimoto, Masaaki Murakami
  Biochemical and biophysical research communications, 703, 149666, 149666, 2024年04月09日, ［国際誌］
  英語, 研究論文（学術雑誌）, The IL-6 amplifier was originally discovered as a mechanism for the enhanced activation of NF-κB in non-immune cells. In the IL-6 amplifier, IL-6-STAT3 and NF-κB stimulation is followed by an excessive production of IL-6, chemokines, and growth factors to develop chronic inflammation preceding the development of inflammatory diseases. Previously, using a shRNA-mediated genome-wide screening, we found that DEAD-Box Helicase 6 (DDX6) is a candidate positive regulator of the amplifier. Here, we investigate whether DDX6 is involved in the pathogenesis of inflammatory diseases via the IL-6 amplifier. We found that DDX6-silencing in non-immune cells suppressed the NF-κB pathway and inhibited activation of the IL-6 amplifier, while the forced expression of DDX6 enhanced NF-κB promoter activity independent of the RNA helicase activity of DDX6. The imiquimod-mediated dermatitis model was suppressed by the siRNA-mediated gene downregulation of DDX6. Furthermore, silencing DDX6 significantly reduced the TNF-α-induced phosphorylation of p65/RelA and IκBα, nuclear localization of p65, and the protein levels of IκBα. Mechanistically, DDX6 is strongly associated with p65 and IκBα, but not TRADD, RIP, or TRAF2, suggesting a novel function of DDX6 as an adaptor protein in the NF-κB pathway. Thus, our findings demonstrate a possible role of DDX6 beyond RNA metabolism and suggest DDX6 is a therapeutic target for inflammatory diseases.
• The gateway reflex regulates tissue-specific autoimmune diseases.
  Yuki Tanaka, Izuru Ohki, Kaoru Murakami, Satoshi Ozawa, Yaze Wang, Masaaki Murakami
  Inflammation and regeneration, 44, 1, 12, 12, 2024年03月07日, ［国際誌］
  英語, 研究論文（学術雑誌）, The dynamic interaction and movement of substances and cells between the central nervous system (CNS) and peripheral organs are meticulously controlled by a specialized vascular structure, the blood-brain barrier (BBB). Experimental and clinical research has shown that disruptions in the BBB are characteristic of various neuroinflammatory disorders, including multiple sclerosis. We have been elucidating a mechanism termed the "gateway reflex" that details the entry of immune cells, notably autoreactive T cells, into the CNS at the onset of such diseases. This process is initiated through local neural responses to a range of environmental stimuli, such as gravity, electricity, pain, stress, light, and joint inflammation. These stimuli specifically activate neural pathways to open gateways at targeted blood vessels for blood immune cell entry. The gateway reflex is pivotal in managing tissue-specific inflammatory diseases, and its improper activation is linked to disease progression. In this review, we present a comprehensive examination of the gateway reflex mechanism.
• Transcutaneous auricular vagus nerve stimulation therapy in patients with cognitively preserved structural focal epilepsy: A case series report.
  Hideaki Shiraishi, Kiyoshi Egawa, Kaoru Murakami, Midori Nakajima, Yuki Ueda, Sachiko Nakakubo, Masashi Narugami, Shuhei Kimura, Takeru Goto, Yasuyoshi Hiramatsu, Masaaki Murakami
  Brain & development, 46, 1, 49, 56, 2024年01月, ［国際誌］
  英語, 研究論文（学術雑誌）, OBJECTIVE: Transcutaneous auricular vagus nerve stimulation (taVNS) was performed in two patients suffering structural focal epilepsy with preserved intellectual ability to show the feasibility of taVNS for specific patient groups. CASE PRESENTATIONS: Patient 1 was a 24-year-old woman with frontal lobe epilepsy who had weekly hyperkinetic seizures despite multiple anti-seizure medications. Patient 2 was a 27-year-old woman with parietal lobe epilepsy and focal cortical dysplasia in the vicinity of the lipoma in the corpus callosum. She experienced weekly focal-impaired awareness seizures even with anti-seizure medication. taVNS was applied to the left earlobe of both patients at 1.5 mA, 25 Hz, 250 μs pulse width, and 30 s stimulation with 30 s rest for 4 h per day. Over an 8-week baseline and 20 weeks of stimulation, the rate of reduction in seizure frequency was evaluated, along with quality-of-life using the Short-Form 36-Item Health survey. RESULTS: At baseline, we measured up to 11 and 12 focal seizures per week in Patient 1 and 2, respectively, with both patients achieving seizure freedom after 4 and 20 weeks taVNS, respectively. Patient 1 and 2 were observed for 18 and 14 months, respectively, including the clinical trial and follow-up observation period. Quality-of-life ratings increased in both patients, and no significant adverse events occurred during the study period. During the maintenance period after 20 weeks, seizures remained absent in Patient 1, and seizures remained reduced in Patient 2. CONCLUSION: Our results demonstrate that taVNS may be a promising tool for structural focal epilepsy with preserved cognitive function. A multicenter double-blind clinical trial is needed to confirm the role of taVNS as an anti-seizure tool.
• Gateway reflexes describe novel neuro-immune communications that establish immune cell gateways at specific vessels.
  Hiroki Tanaka, Rie Hasebe, Kaoru Murakami, Toshiki Sugawara, Takeshi Yamasaki, Masaaki Murakami
  Bioelectronic medicine, 9, 1, 24, 24, 2023年11月08日, ［国際誌］
  英語, 研究論文（学術雑誌）, Neuroinflammation is an important biological process induced by complex interactions between immune cells and neuronal cells in the central nervous system (CNS). Recent research on the bidirectional communication between neuronal and immunological systems has provided evidence for how immune and inflammatory processes are regulated by nerve activation. One example is the gateway reflex, in which immune cells bypass the blood brain barrier and infiltrate the CNS to cause neuroinflammation. We have found several modes of the gateway reflex in mouse models, in which gateways for immune cells are established at specific blood vessels in the spinal cords and brain in experimental autoimmune encephalomyelitis and systemic lupus erythematosus models, at retinal blood vessels in an experimental autoimmune uveitis model, and the ankle joints in an inflammatory arthritis model. Several environmental stimulations, including physical and psychological stresses, activate neurological pathways that alter immunological responses via the gateway reflex, thus contributing to the development/suppression of autoimmune diseases. In the manuscript, we describe the discovery of the gateway reflex and recent insights on how they regulate disease development. We hypothesize that artificial manipulation of specific neural pathways can establish and/or close the gateways to control the development of autoimmune diseases.
• High-precision rapid testing of omicron SARS-CoV-2 variants in clinical samples using AI-nanopore.
  Kaoru Murakami, Shimpei I Kubota, Kumiko Tanaka, Hiroki Tanaka, Keiichiroh Akabane, Rigel Suzuki, Yuta Shinohara, Hiroyasu Takei, Shigeru Hashimoto, Yuki Tanaka, Shintaro Hojyo, Osamu Sakamoto, Norihiko Naono, Takayui Takaai, Kazuki Sato, Yuichi Kojima, Toshiyuki Harada, Takeshi Hattori, Satoshi Fuke, Isao Yokota, Satoshi Konno, Takashi Washio, Takasuke Fukuhara, Takanori Teshima, Masateru Taniguchi, Masaaki Murakami
  Lab on a chip, 23, 22, 4909, 4918, 2023年11月07日, ［国際誌］
  英語, 研究論文（学術雑誌）, A digital platform that can rapidly and accurately diagnose pathogenic viral variants, including SARS-CoV-2, will minimize pandemics, public anxiety, and economic losses. We recently reported an artificial intelligence (AI)-nanopore platform that enables testing for Wuhan SARS-CoV-2 with high sensitivity and specificity within five minutes. However, which parts of the virus are recognized by the platform are unknown. Similarly, whether the platform can detect SARS-CoV-2 variants or the presence of the virus in clinical samples needs further study. Here, we demonstrated the platform can distinguish SARS-CoV-2 variants. Further, it identified mutated Wuhan SARS-CoV-2 expressing spike proteins of the delta and omicron variants, indicating it discriminates spike proteins. Finally, we used the platform to identify omicron variants with a sensitivity and specificity of 100% and 94%, respectively, in saliva specimens from COVID-19 patients. Thus, our results demonstrate the AI-nanopore platform is an effective diagnostic tool for SARS-CoV-2 variants.
• Computer model of IL-6-dependent rheumatoid arthritis in F759 mice.
  Reiji Yamamoto, Satoshi Yamada, Toru Atsumi, Kaoru Murakami, Ari Hashimoto, Seiichiro Naito, Yuki Tanaka, Izuru Ohki, Yuta Shinohara, Norimasa Iwasaki, Akihiko Yoshimura, Jing-Jing Jiang, Daisuke Kamimura, Shintaro Hojyo, Shimpei I Kubota, Shigeru Hashimoto, Masaaki Murakami
  International immunology, 35, 9, 403, 421, 2023年09月05日, ［国際誌］
  英語, 研究論文（学術雑誌）, The interleukin-6 (IL-6) amplifier, which describes the simultaneous activation of signal transducer and activator of transcription 3 (STAT3) and NF-κb nuclear factor kappa B (NF-κB), in synovial fibroblasts causes the infiltration of immune cells into the joints of F759 mice. The result is a disease that resembles human rheumatoid arthritis. However, the kinetics and regulatory mechanisms of how augmented transcriptional activation by STAT3 and NF-κB leads to F759 arthritis is unknown. We here show that the STAT3-NF-κB complex is present in the cytoplasm and nucleus and accumulates around NF-κB binding sites of the IL-6 promoter region and established a computer model that shows IL-6 and IL-17 (interleukin 17) signaling promotes the formation of the STAT3-NF-κB complex followed by its binding on promoter regions of NF-κB target genes to accelerate inflammatory responses, including the production of IL-6, epiregulin, and C-C motif chemokine ligand 2 (CCL2), phenotypes consistent with in vitro experiments. The binding also promoted cell growth in the synovium and the recruitment of T helper 17 (Th17) cells and macrophages in the joints. Anti-IL-6 blocking antibody treatment inhibited inflammatory responses even at the late phase, but anti-IL-17 and anti-TNFα antibodies did not. However, anti-IL-17 antibody at the early phase showed inhibitory effects, suggesting that the IL-6 amplifier is dependent on IL-6 and IL-17 stimulation at the early phase, but only on IL-6 at the late phase. These findings demonstrate the molecular mechanism of F759 arthritis can be recapitulated in silico and identify a possible therapeutic strategy for IL-6 amplifier-dependent chronic inflammatory diseases.
• GM-CSF Promotes the Survival of Peripheral-Derived Myeloid Cells in the Central Nervous System for Pain-Induced Relapse of Neuroinflammation.
  Shiina Matsuyama, Reiji Yamamoto, Kaoru Murakami, Nobuhiko Takahashi, Rieko Nishi, Asuka Ishii, Junko Nio-Kobayashi, Nobuya Abe, Kumiko Tanaka, Jing-Jing Jiang, Tadafumi Kawamoto, Toshihiko Iwanaga, Yuta Shinohara, Takeshi Yamasaki, Izuru Ohki, Shintaro Hojyo, Rie Hasebe, Shimpei I Kubota, Noriyuki Hirata, Daisuke Kamimura, Shigeru Hashimoto, Yuki Tanaka, Masaaki Murakami
  Journal of immunology (Baltimore, Md. : 1950), 211, 1, 34, 42, 2023年07月01日, ［国際誌］
  英語, 研究論文（学術雑誌）, We recently discovered a (to our knowledge) new neuroimmune interaction named the gateway reflex, in which the activation of specific neural circuits establishes immune cell gateways at specific vessel sites in organs, leading to the development of tissue-specific autoimmune diseases, including a multiple sclerosis (MS) mouse model, experimental autoimmune encephalomyelitis (EAE). We have reported that peripheral-derived myeloid cells, which are CD11b+MHC class II+ and accumulate in the fifth lumbar (L5) cord during the onset of a transfer model of EAE (tEAE), play a role in the pain-mediated relapse via the pain-gateway reflex. In this study, we investigated how these cells survive during the remission phase to cause the relapse. We show that peripheral-derived myeloid cells accumulated in the L5 cord after tEAE induction and survive more than other immune cells. These myeloid cells, which highly expressed GM-CSFRα with common β chain molecules, grew in number and expressed more Bcl-xL after GM-CSF treatment but decreased in number by blockade of the GM-CSF pathway, which suppressed pain-mediated relapse of neuroinflammation. Therefore, GM-CSF is a survival factor for these cells. Moreover, these cells were colocalized with blood endothelial cells (BECs) around the L5 cord, and BECs expressed a high level of GM-CSF. Thus, GM-CSF from BECs may have an important role in the pain-mediated tEAE relapse caused by peripheral-derived myeloid cells in the CNS. Finally, we found that blockade of the GM-CSF pathway after pain induction suppressed EAE development. Therefore, GM-CSF suppression is a possible therapeutic approach in inflammatory CNS diseases with relapse, such as MS.
• Association of SNPs in the PAI1 Gene with Disease Recurrence and Clinical Outcome in Bladder Cancer.
  Kaoru Murakami, Hideki Furuya, Kanani Hokutan, Steve Goodison, Ian Pagano, Runpu Chen, Cheng-Huang Shen, Michael W Y Chan, Chi Fai Ng, Takashi Kobayashi, Osamu Ogawa, Makito Miyake, Mark Thornquist, Yoshiko Shimizu, Kazukuni Hayashi, Zhangwei Wang, Herbert Yu, Charles J Rosser
  International journal of molecular sciences, 24, 5, 2023年03月03日, ［国際誌］
  英語, 研究論文（学術雑誌）, PURPOSE: Bladder cancer (BCa) is one of the most common cancer types worldwide and is characterized by a high rate of recurrence. In previous studies, we and others have described the functional influence of plasminogen activator inhibitor-1 (PAI1) in bladder cancer development. While polymorphisms in PAI1 have been associated with increased risk and worsened prognosis in some cancers, the mutational status of PAI1 in human bladder tumors has not been well defined. METHODS: In this study, we evaluated the mutational status of PAI1 in a series of independent cohorts, comprised of a total of 660 subjects. RESULTS: Sequencing analyses identified two clinically relevant 3' untranslated region (UTR) single nucleotide polymorphisms (SNPs) in PAI1 (rs7242; rs1050813). Somatic SNP rs7242 was present in human BCa cohorts (overall incidence of 72%; 62% in Caucasians and 72% in Asians). In contrast, the overall incidence of germline SNP rs1050813 was 18% (39% in Caucasians and 6% in Asians). Furthermore, Caucasian patients with at least one of the described SNPs had worse recurrence-free survival and overall survival (p = 0.03 and p = 0.03, respectively). In vitro functional studies demonstrated that SNP rs7242 increased the anti-apoptotic effect of PAI1, and SNP rs1050813 was related to a loss of contact inhibition associated with cellular proliferation when compared to wild type. CONCLUSION: Further investigation of the prevalence and potential downstream influence of these SNPs in bladder cancer is warranted.
• Gateway reflexes are neural circuits that establish the gateway of immune cells to regulate tissue specific inflammation.
  Keiichiroh Akabane, Kaoru Murakami, Masaaki Murakami
  Expert opinion on therapeutic targets, 27, 6, 469, 477, 2023年, ［国際誌］
  英語, 研究論文（学術雑誌）, INTRODUCTION: Tissue-specific inflammatory diseases are regulated by several mechanisms. The gateway reflex and IL-6 amplifier are two mechanisms involved in diseases that depend on the inflammatory cytokine IL-6. The gateway reflex activates specific neural pathways that cause autoreactive CD4+ T cells to pass through gateways in blood vessels toward specific tissues in tissue-specific inflammatory diseases. These gateways are mediated by the IL-6 amplifier, which describes enhanced NF-κB activation in nonimmune cells including endothelial cells at specific sites. In total, we have reported six gateway reflexes defined by their triggering stimulus: gravity, pain, electric stimulation, stress, light, and joint inflammation. AREAS COVERED: This review summarizes the gateway reflex and IL-6 amplifier for the development of tissue-specific inflammatory diseases. EXPERT OPINION: We expect that the IL-6 amplifier and gateway reflex will lead to novel therapeutic and diagnostic methods for inflammatory diseases, particularly tissue-specific ones.
• SARS-CoV-2 Omicron detection by antigen tests using saliva.
  Kaoru Murakami, Sumio Iwasaki, Satoshi Oguri, Kumiko Tanaka, Rigel Suzuki, Kasumi Hayasaka, Shinichi Fujisawa, Chiaki Watanabe, Satoshi Konno, Isao Yokota, Takasuke Fukuhara, Masaaki Murakami, Takanori Teshima
  Journal of clinical virology plus, 2, 4, 100109, 100109, 2022年11月, ［国際誌］
  英語, 研究論文（学術雑誌）, The Omicron emerged in November 2021 and became the predominant SARS-CoV-2 variant globally. It spreads more rapidly than ancestral lineages and its rapid detection is critical for the prevention of disease outbreaks. Antigen tests such as immunochromatographic assay (ICA) and chemiluminescent enzyme immunoassay (CLEIA) yield results more quickly than standard polymerase chain reaction (PCR). However, their utility for the detection of the Omicron variant remains unclear. We herein evaluated the performance of ICA and CLEIA in saliva from 51 patients with Omicron and 60 PCR negative individuals. The sensitivity and specificity of CLEIA were 98.0% (95%CI: 89.6-100.0%) and 100.0% (95%CI: 94.0-100.0%), respectively, with fine correlation with cycle threshold (Ct) values. The sensitivity and specificity of ICA were 58.8% (95%CI: 44.2-72.4%) and 100.0% (95%CI: 94.0-100.0%), respectively. The sensitivity of ICA was 100.0% (95%CI: 80.5-100.0%) when PCR Ct was less than 25. The Omicron can be efficiently detected in saliva by CLEIA. ICA also detects high viral load Omicron using saliva.
• ATP spreads inflammation to other limbs through crosstalk between sensory neurons and interneurons.
  Rie Hasebe, Kaoru Murakami, Masaya Harada, Nada Halaka, Hiroshi Nakagawa, Fuminori Kawano, Yoshinobu Ohira, Tadafumi Kawamoto, Fiona E Yull, Timothy S Blackwell, Junko Nio-Kobayashi, Toshihiko Iwanaga, Masahiko Watanabe, Nobuhiro Watanabe, Harumi Hotta, Toshihide Yamashita, Daisuke Kamimura, Yuki Tanaka, Masaaki Murakami
  The Journal of experimental medicine, 219, 6, 2022年06月06日, ［国際誌］
  英語, 研究論文（学術雑誌）, Neural circuits between lesions are one mechanism through which local inflammation spreads to remote positions. Here, we show the inflammatory signal on one side of the joint is spread to the other side via sensory neuron-interneuron crosstalk, with ATP at the core. Surgical ablation or pharmacological inhibition of this neural pathway prevented inflammation development on the other side. Mechanistic analysis showed that ATP serves as both a neurotransmitter and an inflammation enhancer, thus acting as an intermediary between the local inflammation and neural pathway that induces inflammation on the other side. These results suggest blockade of this neural pathway, which is named the remote inflammation gateway reflex, may have therapeutic value for inflammatory diseases, particularly those, such as rheumatoid arthritis, in which inflammation spreads to remote positions.
• Gateway reflexes, neuronal circuits that regulate the autoreactive T cells in organs having blood barriers.
  Mona Uchida, Reiji Yamamoto, Shiina Matsuyama, Kaoru Murakami, Rie Hasebe, Shintaro Hojyo, Yuki Tanaka, Masaaki Murakami
  International immunology, 34, 2, 59, 65, 2022年01月22日, ［国際誌］
  英語, 研究論文（学術雑誌）, Gateway reflexes are neural circuits that maintain homeostasis of the immune system. They form gateways for autoreactive T cells to infiltrate the central nervous system in a noradrenaline-dependent manner despite the blood-brain barrier. This mechanism is critical not only for maintaining organ homeostasis but also for inflammatory disease development. Gateway reflexes can be regulated by environmental or artificial stimuli including electrical stimulation, suggesting that the infiltration of immune cells can be controlled by bioelectronic medicine. In this review, we describe the discovery of gateway reflexes and their future directions with special focus on bioelectronic medicine.
• The gateway reflex: breaking through the blood barriers.
  Kaoru Murakami, Yuki Tanaka, Masaaki Murakami
  International immunology, 33, 12, 743, 748, 2021年11月25日, ［国際誌］
  英語, 研究論文（学術雑誌）, We have been studying inflammatory diseases, with a special focus on IL-6, and discovered two concepts related to inflammation development. One is the gateway reflex, which is induced by the activation of specific neural circuits followed by establishing gateways for autoreactive CD4+ T cells to pass through blood barriers toward the central nervous system (CNS) and retina during tissue-specific inflammatory diseases. We found that the formation of these gateways is dependent on the IL-6 amplifier, which is machinery for enhanced NF-κB activation in endothelial cells at specific sites. We have found five gateway reflexes in total. Here, we introduce the gateway reflex and the IL-6 amplifier.
• Rhodobacter azotoformans LPS (RAP99-LPS) Is a TLR4 Agonist That Inhibits Lung Metastasis and Enhances TLR3-Mediated Chemokine Expression.
  Kaoru Murakami, Daisuke Kamimura, Rie Hasebe, Mona Uchida, Nobuya Abe, Reiji Yamamoto, Jing-Jing Jiang, Yasuhiro Hidaka, Yuko Nakanishi, Shuzo Fujita, Yuki Toda, Nobuhiro Toda, Hiroki Tanaka, Shizuo Akira, Yuki Tanaka, Masaaki Murakami
  Frontiers in immunology, 12, 675909, 675909, 2021年, ［国際誌］
  英語, 研究論文（学術雑誌）, The lipopolysaccharides (LPSs) of Rhodobacter are reported to be TLR4 antagonists. Accordingly, the extract of Rhodobacter azotoformans (RAP99) is used as a health supplement for humans and animals in Japan to regulate immune responses in vivo. We previously analyzed the LPS structure of RAP99 (RAP99-LPS) and found it is different from that of E. coli-LPS but similar to lipid A from Rhodobacter sphaeroides (RSLA), a known antagonist of TLR4, with both having three C14 fatty acyl groups, two C10 fatty acyl groups, and two phosphates. Here we show that RAP99-LPS has an immune stimulatory activity and acts as a TLR4 agonist. Pretreatment of RAP99-LPS suppressed E. coli-LPS-mediated weight loss, suggesting it is an antagonist against E. coli-LPS like other LPS isolated from Rhodobacter. However, injections of RAP99-LPS caused splenomegaly and increased immune cell numbers in C57BL/6 mice but not in C3H/HeJ mice, suggesting that RAP99-LPS stimulates immune cells via TLR4. Consistently, RAP99-LPS suppressed the lung metastasis of B16F1 tumor cells and enhanced the expression of TLR3-mediated chemokines. These results suggest that RAP99-LPS is a TLR4 agonist that enhances the activation status of the immune system to promote anti-viral and anti-tumor activity in vivo.