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Autophagy has been linked to a wide range of functions, including a degradative process that defends host cells against pathogens. Although the involvement of autophagy in HBV infection has become apparent, it remains unknown whether selective autophagy plays a critical role in HBV restriction. Here, we report that a member of the galectin family, GAL9, directs the autophagic degradation of HBV HBc. BRET screening revealed that GAL9 interacts with HBc in living cells. Ectopic expression of GAL9 induces the formation of HBc-containing cytoplasmic puncta through interaction with another antiviral factor viperin, which co-localized with the autophagosome marker LC3. Mechanistically, GAL9 associates with HBc via viperin at the cytoplasmic puncta and enhanced the auto-ubiquitination of RNF13, resulting in p62 recruitment to form LC3-positive autophagosomes. Notably, both GAL9 and viperin are type I IFN-stimulated genes that act synergistically for the IFN-dependent proteolysis of HBc in HBV-infected hepatocytes. Collectively, these results reveal a previously undescribed antiviral mechanism against HBV in infected cells and a form of crosstalk between the innate immune system and selective autophagy in viral infection. In human cells, invading pathogens trigger an innate immune response that helps prevent viral replication and spread. Here, the authors reveal a mechanism of innate immunity that selectively leads to the autophagic degradation of hepatitis B virus core protein.

The COVID-19 pandemic is an unprecedented threat to humanity that has provoked global health concerns. Since the etiopathogenesis of this illness is not fully characterized, the prognostic factors enabling treatment decisions have not been well documented. Accurately predicting the progression of the disease would aid in appropriate patient categorization and thus help determine the best treatment option. Here, we have introduced a proteomic approach utilizing data-independent acquisition mass spectrometry (DIA-MS) to identify the serum proteins that are closely associated with COVID-19 prognosis. Twenty-seven proteins were differentially expressed between severely ill COVID-19 patients with an adverse or favorable prognosis. Ingenuity Pathway Analysis revealed that 15 of the 27 proteins might be regulated by cytokine signaling relevant to interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF), and their differential expression was implicated in the systemic inflammatory response and in cardiovascular disorders. We further evaluated practical predictors of the clinical prognosis of severe COVID-19 patients. Subsequent ELISA assays revealed that CHI3L1 and IGFALS may serve as highly sensitive prognostic markers. Our findings can help formulate a diagnostic approach for accurately identifying COVID-19 patients with severe disease and for providing appropriate treatment based on their predicted prognosis.

Cancer stem cells (CSCs) represent a subset of cells within tumours that exhibit self-renewal properties and the capacity to seed tumours. CSCs are typically refractory to conventional treatments and have been associated to metastasis and relapse. Salinomycin operates as a selective agent against CSCs through mechanisms that remain elusive. Here, we provide evidence that a synthetic derivative of salinomycin, which we named ironomycin (AM5), exhibits a more potent and selective activity against breast CSCs in vitro and in vivo , by accumulating and sequestering iron in lysosomes. In response to the ensuing cytoplasmic depletion of iron, cells triggered the degradation of ferritin in lysosomes, leading to further iron loading in this organelle. Iron-mediated production of reactive oxygen species promoted lysosomal membrane permeabilization, activating a cell death pathway consistent with ferroptosis. These findings reveal the prevalence of iron homeostasis in breast CSCs, pointing towards iron and iron-mediated processes as potential targets against these cells. Cancer stem cells are typically refractory to conventional treatments. Now, an unprecedented mechanism has been discovered by which salinomycin and derivatives can sequester iron in lysosomes leading to cytoplasmic iron depletion and the subsequent production of reactive oxygen species that are lethal to the cell. This discovery of the importance of iron in cancer stem cell maintenance provides an opportunity for developing new therapeutics.

Sodium taurocholate cotransporting polypeptide (NTCP) is a host cell receptor required for hepatitis B virus (HBV) entry. However, the susceptibility of NTCP-expressing cells to HBV is diverse depending on the culture condition. Stimulation with epidermal growth factor (EGF) was found to potentiate cell susceptibility to HBV infection. Here, we show that EGF receptor (EGFR) plays a critical role in HBV virion internalization. In EGFR-knockdown cells, HBV or its preS1-specific fluorescence peptide attached to the cell surface, but its internalization was attenuated. PreS1 internalization and HBV infection could be rescued by complementation with functional EGFR. Interestingly, the HBV/preS1–NTCP complex at the cell surface was internalized concomitant with the endocytotic relocalization of EGFR. Molecular interaction between NTCP and EGFR was documented by immunoprecipitation assay. Upon dissociation from functional EGFR, NTCP no longer functioned to support viral infection, as demonstrated by either (i) the introduction of NTCP pointmutation that disrupted its interaction with EGFR, (ii) the detrimental effect of decoy peptide interrupting the NTCP–EGFR interaction, or (iii) the pharmacological inactivation of EGFR. Together, these data support the crucial role of EGFR in mediating HBV–NTCP internalization into susceptible cells. EGFR thus provides a yet unidentified missing link from the cell-surface HBV–NTCP attachment to the viral invasion beyond the host cell membrane

Post-acute sequelae of SARS-CoV-2 infection (PASC), commonly known as “Long COVID”, represents a significant clinical challenge characterized by persistent symptoms following acute COVID-19 infection. We conducted a comprehensive retrospective cohort study to identify serum autoantibody biomarkers associated with PASC. Initial screening using a protein bead array comprising approximately 20,000 human proteins identified several candidate PASC-associated autoantibodies. Subsequent validation by enzyme-linked immunosorbent assay (ELISA) in an expanded cohort—consisting of PASC patients, non-PASC COVID-19 convalescents, and pre-pandemic healthy controls—revealed two promising biomarkers: autoantibodies targeting PITX2 and FBXO2. PITX2 autoantibodies demonstrated high accuracy in distinguishing PASC patients from both non-PASC convalescents (area under the curve [AUC] = 0.891) and healthy controls (AUC = 0.866), while FBXO2 autoantibodies showed moderate accuracy (AUC = 0.762 and 0.786, respectively). Notably, the levels of these autoantibodies were associated with several PASC symptoms, including fever, dyspnea, palpitations, loss of appetite, and brain fog. The identification of PITX2 and FBXO2 autoantibodies as biomarkers not only enhances our understanding of PASC pathophysiology but also provides promising candidates for further investigation.

PurposeAldehyde dehydrogenase1 (ALDH1) is widely accepted as a stem cell marker for normal breast as well as in breast cancer. Although the clinical impact of ALDH1 was observed in our previous study, we do not know how ALDH1 affects stem cell features resulting in worsening of prognosis in breast cancer. The purpose of this study is to explore ALDH1-related gene and its function on cancer stem cell (CSC).MethodsIn five cases of ALDH1-positive triple-negative breast cancer, mRNA expression profile was compared between ALDH1-positive and ALDH1-negative cells by Affymetrix microarray analysis after microdissection. Among the genes modulated in ALDH1-positive cells, we focused on H19, which encodes a long non-coding RNA, in this study. An in-vitro study was conducted with H19 siRNA in HCC1934 and iCSCL10A cell lines. The association of H19 with prognosis was examined in 180 breast cancer cases.ResultsNetwork analysis revealed the existence of five genes related with H19, including miR-103, miR-107, let-7, miR-29b-1, and Trx. In-vitro analysis showed that suppression of H19 using siRNA reduces sphere formation capacity in both HCC1934 and iCSCL10A cell lines. In clinical studies, H19 expression was associated with hormone negativity, tumor size, and nodal status. Patients with H19 expression had significantly poor disease-free survival (DFS) (26.3 vs. 64.8% at 5 years, p = 0.001) and overall survival (OS) (28.9 vs. 68.3% at 5 years, p = 0.004). The effect of H19 expression on prognosis was the most significant in triple-negative breast cancer compared to that in other subtypes (20.0 vs. 65.4% at 5 years DFS, p = 0.012, 20.0 vs. 69.2% at 5 years OS, p = 0.016).ConclusionThis study indicated that H19 was associated with stem cell phenotype in ALDH1-positive breast cancer. H19 regulates CSC and is associated with poor prognosis in breast cancer patients, particularly in triple-negative subtype.

Mechanisms of hepatitis B virus (HBV) reactivation after hepatitis C virus (HCV) elimination by direct-acting antiviral (DAA) treatment in HBV/HCV-co-infected patients remain unclear. We examined RIG-I-like helicase (RLH) pathway activation by HBV mono-infection, HCV mono-infection or HBV/HCV co-infection and interference between HBV and HCV in primary human hepatocytes. Interference between HBV and HCV and HBV reactivation after DAA treatment in humanized-liver mice were assessed. HCV infection activated RLH pathway, as evidenced by RIG-I, ISG15 and ISG56 expression induction; HBV caused only RIG-I induction in vitro . RLH activation was also found in HBV/HCV-co-infected cells, and HBV replication were suppressed in HBV/HCV-co-infected than in HBV-mono-infected cells. siRNA-mediated double knockdown of ISG15 and ISG56 increased HBV replication in HBV/HCV-co-infected cells. HCV infection activated RLH pathway and suppressed HBV replication in humanized-liver mice. Subsequent elimination of HCV by DAA administration downregulated RLH pathway and upregulated HBV replication in mice. RLH pathway was activated in livers of chronic hepatitis C patients compared to those of chronic hepatitis B or non-B, non-C patients. The RLH pathway activation was downregulated by HCV elimination. In conclusion, HCV infection activated RLH pathway and suppressed HBV replication in human hepatocytes. HCV elimination upregulated HBV replication, probably through RLH pathway downregulation.

Traumatic brain injury (TBI), characterized by acute neurological dysfunction, is one of the best known environmental risk factors for chronic traumatic encephalopathy and Alzheimer’s disease, the defining pathologic features of which include tauopathy made of phosphorylated tau protein (P-tau). However, tauopathy has not been detected in the early stages after TBI, and how TBI leads to tauopathy is unknown. Here we find robust cis P-tau pathology after TBI in humans and mice. After TBI in mice and stress in vitro , neurons acutely produce cis P-tau, which disrupts axonal microtubule networks and mitochondrial transport, spreads to other neurons, and leads to apoptosis. This process, which we term ‘cistauosis’, appears long before other tauopathy. Treating TBI mice with cis antibody blocks cistauosis, prevents tauopathy development and spread, and restores many TBI-related structural and functional sequelae. Thus, cis P-tau is a major early driver of disease after TBI and leads to tauopathy in chronic traumatic encephalopathy and Alzheimer’s disease. The cis antibody may be further developed to detect and treat TBI, and prevent progressive neurodegeneration after injury. Here the cis form of tau protein, which disrupts axonal microtubules and transport, spreads to other neurons, and leads to apoptosis in vitro and in vivo , is found to be produced by neurons immediately after traumatic brain injury (TBI); treating TBI mice with cis antibody blocks early production of cis tau, prevents tauopathy and spread and restores brain structural and functional outcomes, and may be further developed to treat TBI and to prevent neurodegeneration after injury. cis P-tau tauopathy in traumatic brain injury The symptoms of traumatic brain injury (TBI), a common condition in players of contact sports and in the military, are associated with acute neurological dysfunction and TBI is a major risk factor for Alzheimer's disease. Tauopathy associated with the aggregation of phosphorylated tau protein (P-tau) in the brain is a defining feature of the neurodegeneration associated with chronic traumatic encephalopathy and Alzheimer's but it has not been observed in the early stages of TBI. Here Kun Ping Lu and colleagues show that tauopathy caused by cis P-tau, but not trans P-tau, is an early driver of brain injury in patients with TBI and in mouse models. Treating TBI mice with cis antibody blocks early production of cis P-tau and prevents further tauopathy and spread, and may be further developed to treat TBI after injury.

Microbial pathogens, including bacteria, fungi and viruses, can develop resistance to clinically used drugs; therefore, finding new therapeutic agents is an ongoing challenge. Recently, we reported the photoimmuno-antimicrobial strategy (PIAS), a type of photoimmunotechnology, that enables molecularly targeted elimination of a wide range of microbes, including the viral pathogen severe acute respiratory syndrome coronavirus 2 and the multidrug-resistant bacterial pathogen methicillin-resistant Staphylococcus aureus (MRSA). PIAS works in the same way as photoimmunotherapy (PIT), which has been used to treat recurrent head and neck cancer in Japan since 2020. Both PIAS and PIT use a monoclonal antibody conjugated to a phthalocyanine derivative dye that undergoes a shape change when photoactivated. This shape change induces a structural change in the antibody–dye conjugate, resulting in physical stress within the binding sites of the conjugate and disrupting them. Therefore, targeting accuracy and flexibility can be determined based on the specificity of the antibody used. In this protocol, we describe how to design a treatment strategy, label monoclonal antibodies with the dye and characterize the products. We provide detailed examples of how to set up and perform PIAS and PIT applications in vitro and in vivo. These examples are PIAS against microbes using MRSA as a representative subject, PIAS against viruses using severe acute respiratory syndrome coronavirus 2 in VeroE6/TMPRSS2 cells, PIAS against MRSA-infected animals, and in vitro and in vivo PIT against cancer cells. The in vitro and in vivo protocols can be completed in ~3 h and 2 weeks, respectively. Key points Photoimmunotherapy, an effective treatment for head and neck cancer, is a technique that uses a monoclonal antibody labeled with a phthalocyanine derivative to disrupt the binding site after photoactivation. This technique allows for both ‘target specificity’ and ‘flexibility in target selection’, leading to the development of a novel antimicrobial strategy that enables targeted elimination of microbes, regardless of the target species or drug resistance status of the target. Microbial pathogens develop resistance to clinically used drugs, and finding new therapeutics is an ongoing challenge. The photoimmuno-antimicrobial strategy described in this protocol is a general approach to target specific elimination.

Up to seven doses of coronavirus disease 2019 (COVID-19) mRNA vaccines (BNT162b2) were administered to Japanese healthcare workers, until February 2024. The monovalent Omicron XBB.1.5 vaccine (hereafter called XBB.1.5 vaccine) was used for dose 7. Although the XBB.1.5 vaccine has been reported to induce a robust increase in neutralizing antibodies against the currently circulating Omicron variant BA.2.86, little is known about its serological effects in Japan, where the BNT162b2 mRNA vaccine is the most frequently administered in the world. Twenty-five recipients of the XBB.1.5 vaccine, categorized as seronegative (n = 18) or seropositive (n = 7) based on their recent history of COVID-19, were analyzed. Neutralizing antibody titers against Omicron subvariants, receptor binding domain (RBD) IgG levels, IgG subclass distribution, and T-cell responses were assessed. We found a significant increase in neutralizing antibody titers against XBB.1.5 and BA.2.86 variants following XBB.1.5 vaccination, particularly in seropositive individuals. No significant change in total RBD IgG levels was observed, indicating efficient induction of antibodies targeting regions outside the RBD by XBB.1.5 vaccination. IgG subclass analysis demonstrated no significant subclass switching after vaccination. T-cell responses against the virus were comparable between seropositive and seronegative groups. The study suggests that XBB.1.5 vaccination enhances humoral immunity against Omicron variants without significant IgG subclass switching. However, some individuals with low pre-vaccination IgG titers did not exhibit increased antibody levels post-vaccination, raising concerns about potential immune tolerance.