Biology subjects

Ishii, K. J.

Publications and source records attributed to Ishii, K. J..

9 recordsLinked to original sources

bioRxiv2026

STING restrains calcium-dependent microglial phagocytosis and protects against neuronal loss and cognitive impairment during epileptogenesis

Epileptogenesis is accompanied by robust neuroinflammation, yet the molecular pathways linking innate immune activation to neuronal dysfunction remain incompletely defined. Given the established pro-inflammatory role of the stimulator of interferon genes (STING), we initially hypothesized that its loss would attenuate neuroinflammatory responses during epileptogenesis. Contrary to our expectation, we found that STING deficiency instead amplified microglial activation. Using a kainic acid mouse model of temporal lobe epilepsy (TLE), we show that STING-deficient microglia exhibit pronounced lysosomal expansion and enhanced phagocytic engulfment of neurons, leading to increased hippocampal neuronal loss and cognitive impairment. Mechanistically, STING deficiency increased the expression and altered the subcellular distribution of stromal interaction molecule 1 (STIM1), an endoplasmic reticulum Ca{superscript 2} sensor that mediates store-operated calcium entry (SOCE), resulting in dysregulated intracellular calcium dynamics and elevated SOCE activity. Pharmacological inhibition of SOCE reduced microglia-neuron interactions and microglial phagocytic engulfment, improved neuronal survival in the CA3 region of the hippocampus, and rescued cognitive deficits following status epilepticus. Collectively, these findings redefine STING as a negative regulator of microglial activation and identify a previously unrecognized STING-STIM1-SOCE axis that constrains calcium-dependent microglial phagocytosis during epileptogenesis, highlighting microglial calcium signaling as a potential therapeutic target in TLE.

neuroscience↗

bioRxiv2026

Prime-Target neoantigen vaccination unleashes unprecedented T cell immunity within ''cold'' immunosuppressive tumors

"Cold" immunosuppressive solid tumors are hard-to-treat cancers that are non-responsive to immunotherapies. Their immunosuppressive tumor microenvironment (TME) excludes and inhibits T cells and thereby hampers the therapeutic efficacy of cancer vaccines and immune checkpoint blockade. To overcome this, we employed a "Prime-Target" (P/T) neoantigen vaccination strategy that combines subcutaneous (SQ) and intra-tumor (IT) neopeptide vaccinations to first prime potent systemic neoantigen-specific T cell immunity and then trigger intratumoral T cell recruitment. Using immunotherapy non-responsive murine tumor models with pronounced immunosuppressive TMEs, we demonstrate that P/T neopeptide vaccination resulted in extraordinary tumor control and TME remodeling. P/T vaccination elicited strong systemic anti-tumor responses as well as potent and rapid recruitment of clonal CD4+ Th1 and non-exhausted CD8+ T cells into tumors that carried novel T cell receptors (TCR) and were vaccine neopeptide-specific. Concurrently, P/T vaccination reshaped the TME by decreasing suppressive Treg and M2 macrophages, and dramatically increasing the ratio of effector T cells to Treg and M2 macrophages. Vaccination-induced tumor control was neopeptide-dependent and required concurrent IT administration of both neopeptides and adjuvants. Our study highlights P/T neoantigen vaccination as a promising strategy to overcome T cell exclusion within "cold" immunosuppressive solid tumors and thereby unleash unprecedented anti-tumor immunity.

immunology↗

bioRxiv2023

Virological characteristics of the SARS-CoV-2 JN.1 variant

The SARS-CoV-2 BA.2.86 lineage, first identified in August 2023, is phylogenetically distinct from the currently circulating SARS-CoV-2 Omicron XBB lineages, including EG.5.1 and HK.3. Comparing to XBB and BA.2, BA.2.86 carries more than 30 mutations in the spike (S) protein, indicating a high potential for immune evasion. BA.2.86 has evolved and its descendant, JN.1 (BA.2.86.1.1), emerged in late 2023. JN.1 harbors S:L455S and three mutations in non-S proteins. S:L455S is a hallmark mutation of JN.1: we have recently shown that HK.3 and other "FLip" variants carry S:L455F, which contributes to increased transmissibility and immune escape ability compared to the parental EG.5.1 variant. Here, we investigated the virological properties of JN.1.

microbiology↗

bioRxiv2023

5,6-dimethylxanthenone-4-acetic acid (DMXAA), a Partial STING Agonist, Competes for Human STING Activation

5,6-dimethylxanthenone-4-acetic acid (DMXAA) is a mouse-selective stimulator of interferon gene (STING) agonist exerting STING-dependent anti-tumor activity. Although DMXAA can not fully activate human STING, DMXAA reached phase III in lung cancer clinical trials. How DMXAA is effective against human lung cancer is completely unknown. Here, we show that DMXAA is a partial STING agonist interfering with agonistic STING activation, which may explain its partial anti-tumor effect observed in humans, as STING was reported to be pro-tumorigenic for lung cancer cells with low antigenicity. Furthermore, we developed a DMXAA derivative--3-hydroxy-5-(4-hydroxybenzyl)-4-methyl-9H-xhanthen-9one (HHMX)--that can potently antagonize STING-mediated immune responses both in humans and mice. Notably, HHMX suppressed aberrant responses induced by STING gain-of-function mutations causing STING-associated vasculopathy with onset in infancy (SAVI) in in vitro experiments. Furthermore, HHMX treatment suppressed aberrant STING pathway activity in peripheral blood mononuclear cells from SAVI patients. Lastly, HHMX showed a potent therapeutic effect in SAVI mouse model by mitigating disease progression. Thus, HHMX offers therapeutic potential for STING-associated autoinflammatory diseases.

immunology↗

bioRxiv2023

A stress sensor IRE1α is required for bacterial exotoxin-induced inflammasome activation in tissue-resident macrophages

Cholera toxin (CT), a bacterial exotoxin composed of one A subunit (CTA) and five B subunits (CTB), functions as an immune adjuvant. CTB can induce production of interleukin-1{beta} (IL-1{beta}), a proinflammatory cytokine, in synergy with a lipopolysaccharide (LPS), from resident peritoneal macrophages (RPMs) through the pyrin and NLRP3 inflammasomes. However, how CTB or CT activates these inflammasomes in the macrophages has been unclear. Here, we clarified the roles of IRE1, an endoplasmic reticulum (ER) stress sensor, in CT-induced IL-1{beta} production from RPMs. In RPMs, CTB is incorporated into ER and induced ER stress responses, depending on GM1, a cell membrane ganglioside. IRE1-deficient RPMs showed a significant impairment of CT- or CTB-induced IL-1{beta} production, indicating that IRE1 was required for CT- or CTB-induced IL-1{beta} production from RPMs. This study first demonstrates the critical roles of IRE1 in activation of both NLRP3 and pyrin inflammasomes in tissue-resident macrophages. One sentence summaryIRE1 is required for NLRP3 and pyrin-mediated IL-1{beta} production

immunology↗

bioRxiv2022

Virological characteristics of the novel SARS-CoV-2 Omicron variants including BA.2.12.1, BA.4 and BA.5

After the global spread of SARS-CoV-2 Omicron BA.2 lineage, some BA.2-related variants that acquire mutations in the L452 residue of spike protein, such as BA.2.9.1 and BA.2.13 (L452M), BA.2.12.1 (L452Q), and BA.2.11, BA.4 and BA.5 (L452R), emerged in multiple countries. Our statistical analysis showed that the effective reproduction numbers of these L452R/M/Q-bearing BA.2-related Omicron variants are greater than that of the original BA.2. Neutralization experiments revealed that the immunity induced by BA.1 and BA.2 infections is less effective against BA.4/5. Cell culture experiments showed that BA.2.12.1 and BA.4/5 replicate more efficiently in human alveolar epithelial cells than BA.2, and particularly, BA.4/5 is more fusogenic than BA.2. Furthermore, infection experiments using hamsters indicated that BA.4/5 is more pathogenic than BA.2. Altogether, our multiscale investigations suggest that the risk of L452R/M/Q-bearing BA.2-related Omicron variants, particularly BA.4 and BA.5, to global health is potentially greater than that of original BA.2. HighlightsO_LISpike L452R/Q/M mutations increase the effective reproduction number of BA.2 C_LIO_LIBA.4/5 is resistant to the immunity induced by BA.1 and BA.2 infections C_LIO_LIBA.2.12.1 and BA.4/5 more efficiently spread in human lung cells than BA.2 C_LIO_LIBA.4/5 is more pathogenic than BA.2 in hamsters C_LI

microbiology↗

bioRxiv2022

Virological characteristics of SARS-CoV-2 BA.2 variant

Soon after the emergence and global spread of a new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron lineage, BA.1 (ref1, 2), another Omicron lineage, BA.2, has initiated outcompeting BA.1. Statistical analysis shows that the effective reproduction number of BA.2 is 1.4-fold higher than that of BA.1. Neutralisation experiments show that the vaccine-induced humoral immunity fails to function against BA.2 like BA.1, and notably, the antigenicity of BA.2 is different from BA.1. Cell culture experiments show that BA.2 is more replicative in human nasal epithelial cells and more fusogenic than BA.1. Furthermore, infection experiments using hamsters show that BA.2 is more pathogenic than BA.1. Our multiscale investigations suggest that the risk of BA.2 for global health is potentially higher than that of BA.1.

microbiology↗

bioRxiv2021

Optimization of an LNP-mRNA vaccine candidate targeting SARS-CoV-2 receptor-binding domain

In 2020, two mRNA-based vaccines, encoding the full length of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein, have been introduced for control of the coronavirus disease (COVID-19) pandemic1,2. However, reactogenicity, such as fever, caused by innate immune responses to the vaccine formulation remains to be improved. Here, we optimized a lipid nanoparticle (LNP)-based mRNA vaccine candidate, encoding the SARS-CoV-2 spike protein receptor-binding domain (LNP-mRNA-RBD), which showed improved immunogenicity by removing reactogenic materials from the vaccine formulation and protective potential against SARS-CoV-2 infection in cynomolgus macaques. LNP-mRNA-RBD induced robust antigen-specific B cells and follicular helper T cells in the BALB/c strain but not in the C57BL/6 strain; the two strains have contrasting abilities to induce type I interferon production by dendritic cells. Removal of reactogenic materials from original synthesized mRNA by HPLC reduced type I interferon (IFN) production by dendritic cells, which improved immunogenicity. Immunization of cynomolgus macaques with an LNP encapsulating HPLC-purified mRNA induced robust anti-RBD IgG in the plasma and in various mucosal areas, including airways, thereby conferring protection against SARS-CoV-2 infection. Therefore, fine-tuning the balance between the immunogenic and reactogenic activity of mRNA-based vaccine formulations may offer safer and more efficacious outcomes.

immunology↗

bioRxiv2020

Immunological role of primary cilia of dendritic cells in human skin disease

Primary cilia are a unique organelle, known to provide a signaling hub for variety of cell activities. Their potential role(s) in human immune homeostasis and diseases, however, have yet to be explored. Here, we show that human dendritic cells (DCs) express primary cilia-like structure. The primary cilia growth during DC proliferation by GM-CSF was shut off by DC maturation agents, suggesting the role of primary cilia to transduce proliferation signaling. PDGFR pathway, one of proliferation signal in primary cilia, promoted DC proliferation in a dependent manner of intra-flagellar transport system. In epidermis with atopic dermatitis patients, aberrant ciliated langerhans cells and keratinocytes with showing immature state were observed that may play a potential role in inflammation and skin barrier disorder.

cell biology↗