Irregular Tremulous Movements and Infrequent Seizures: A Clinical-Electrophysiological Diagnosis of Benign Adult Familial Myoclonus Epilepsy.

We report a case involving a 31-year-old male without any known precipitating injuries presenting with involuntary finger movements and rare seizures. There was a noted family history of tremulous movements. Yet the characteristics of his finger movements were irregular and not typical of essential tremor (ET). Electrophysiological examinations, including video EEG, showed no epileptic discharges, and brain MRI results were normal. However, somatosensory evoked potentials (SEP) revealed the presence of giant SEP, and a positive cortical (C)-reflex was observed, leading to a clinical diagnosis of benign adult familial myoclonus epilepsy (BAFME). Management with valproic acid and perampanel resulted in a significant reduction of symptoms. This case highlights the necessity of considering BAFME in the differential diagnosis for atypical tremorous finger movements, especially with a relevant family history, and the critical role of electrophysiological findings indicative of cortical hyperexcitability.

ROR2 expression predicts human induced pluripotent stem cell differentiation into neural stem/progenitor cells and GABAergic neurons.

Despite the development of various in vitro differentiation protocols for the efficient derivation of specific cell types, human induced pluripotent stem cell (hiPSC) lines have varing ability to differentiate into specific lineages. Therefore, surrogate markers for accurately predicting the differentiation propensity of hiPSC lines may facilitate cell-based therapeutic product development and manufacture. We attempted to identify marker genes that could predict the differentiation propensity of hiPSCs into neural stem/progenitor cells (NS/PCs). Using Spearman's rank correlation coefficients, we investigated genes in the undifferentiated state, the expression levels of which were significantly correlated with the neuronal differentiation propensity of several hiPSC lines. Among genes significantly correlated with NS/PC differentiation (P < 0.01), we identified ROR2 as a novel predictive marker. ROR2 expression in hiPSCs was negatively correlated with NS/PC differentiation tendency, regardless of the differentiation method, whereas its knockdown enhanced differentiation. ROR2 regulates NS/PC differentiation, suggesting that ROR2 is functionally essential for NS/PC differentiation. Selecting cell lines with relatively low ROR2 expression facilitated identification of hiPSCs that can differentiate into NS/PCs. Cells with ROR2 knockdown showed increased efficiency of differentiation into forebrain GABAergic neurons compared to controls. These findings suggest that ROR2 is a surrogate marker for selecting hiPSC lines appropriate for NS/PC and GABAergic neuronal differentiations.

Micromorphological observation of HLE cells under knockdown of Fascin using LV-SEM.

Liver cancer is one of the most prevalent cancers in Japan with hepatocellular carcinoma (HCC) as the major histological subtype. Successful novel treatments for HCC have been reported; however, recurrences or metastasis may occur, which results in poor prognoses and high mortality of HCC patients. Fascin, an actin-bundling protein, regulates cell adhesion, migration, and invasion. Its overexpression positively correlates with poor prognosis of malignant tumors, and Fascin is considered as one of the tumor biomarkers and therapeutic target proteins. In this study, we attempted to reveal the relationship between Fascin and HCC using HLE, one of the human HCC cell lines. We performed the study with classical immunocytochemistry and recently developed techniques, such as wound-healing assay, spheroid cultivation, and low-vacuum scanning electron microscopy (LV-SEM). Non-Fascin-knockdown (FKD) cell spheroid had a regular spherical appearance with tight cell-cell connections, while FKD cell spheroid had an irregular shape with loose cell-cell connections. Cells of non-FKD spheroid presented fibrous protrusions on the cell surface, contrarily, cells of FKD spheroids showed bulbous-shaped protrusions. Morphological observation of FKD and non-FKD HLE spheroids were performed using LV-SEM. Our study may help to reveal the roles of Fascin in the process of HCC formation and its malignancy.

Disseminated non-tuberculous mycobacterial infection caused by Mycobacterium obuense in an immunocompromised patient: a case report.

BACKGROUND: Mycobacterium obuense (M. obuense) is a rapidly growing mycobacterium (RGM) which has been considered nonpathogenic. Here, we report a case of disseminated non-tuberculous mycobacterial (NTM) infection caused by M. obuense in an immunocompromised patient. CASE PRESENTATION: A 16-year-old boy was referred to our hospital due to acute myeloid leukemia. During the treatment of leukemia, the patient exhibited continuous fever, and diffuse miliary nodules with random distribution were found on chest computed tomography. Repeated examinations of bacterial culture tests revealed sputum and urine samples to be smear-positive for acid-fast bacillus, and blood culture from a peripherally inserted central catheter line showed the growth of NTM. The NTM species was identified as M. obuense by mass spectrometry and confirmed by genome sequencing. Combination therapy with amikacin, rifampicin, azithromycin, and moxifloxacin significantly improved the patient's symptoms and radiological findings. CONCLUSION: We report a case of disseminated NTM infection caused by M. obuense for which combination anti-microbial therapy was effective. An immunocompromised host indwelling catheter is at risk of RGM bloodstream infections. Although relatively rare, M. obuense may be considered as a potential pathogen causing infectious diseases, especially in high-risk patients.

Single-Cell RNA-Seq Reveals LRRC75A-Expressing Cell Population Involved in VEGF Secretion of Multipotent Mesenchymal Stromal/Stem Cells Under Ischemia.

Human multipotent mesenchymal stromal/stem cells (MSCs) have been utilized in cell therapy for various diseases and their clinical applications are expected to increase in the future. However, the variation in MSC-based product quality due to the MSC heterogeneity has resulted in significant constraints in the clinical utility of MSCs. Therefore, we hypothesized that it might be important to identify and ensure/enrich suitable cell subpopulations for therapies using MSC-based products. In this study, we aimed to identify functional cell subpopulations to predict the efficacy of angiogenic therapy using bone marrow-derived MSCs (BM-MSCs). To assess its angiogenic potency, we observed various levels of vascular endothelial growth factor (VEGF) secretion among 11 donor-derived BM-MSC lines under in vitro ischemic culture conditions. Next, by clarifying the heterogeneity of BM-MSCs using single-cell RNA-sequencing analysis, we identified a functional cell subpopulation that contributed to the overall VEGF production in BM-MSC lines under ischemic conditions. We also found that leucine-rich repeat-containing 75A (LRRC75A) was more highly expressed in this cell subpopulation than in the others. Importantly, knockdown of LRRC75A using small interfering RNA resulted in significant inhibition of VEGF secretion in ischemic BM-MSCs, indicating that LRRC75A regulates VEGF secretion under ischemic conditions. Therefore, LRRC75A may be a useful biomarker to identify cell subpopulations that contribute to the angiogenic effects of BM-MSCs. Our work provides evidence that a strategy based on single-cell transcriptome profiles is effective for identifying functional cell subpopulations in heterogeneous MSC-based products.

Downregulation of fascin induces collective cell migration in triple­negative breast cancer.

Breast cancer (BC) is one of the most common types of cancer affecting female patients. Triple­negative BC (TNBC) is an aggressive subtype. Fascin, an actin­bundling protein, serves a significant role in cancer metastasis. Fascin overexpression is associated with poor prognosis of BC. To confirm the relationship between fascin expression and BC malignancy, the present study reviewed clinical data from 100 Japanese patients with BC and performed fresh immunohistochemical fascin examination of tissue samples. Statistical analyses showed metastasis or recurrence in 11 of 100 patients and a significant association between high fascin expression and poor prognosis. The TNBC subtype was also associated with high fascin expression. However, a few cases developed poor prognosis regardless of negative or slightly positive fascin expression. The present study established fascin knockdown (FKD) MDA­MB­231, a TNBC cell line, and investigated morphological effects of fascin on TNBC cells. FKD cells exhibited cell­cell connections and bulbous nodules of various sizes on the cell surface. Conversely, non­FKD MDA­MB­231 cells exhibited loose cell­cell connections with numerous filopodia on the cell surface. Filopodia, actin­rich plasma membrane protrusions, are composed of fascin and control cell­cell interaction, migration and wound healing. Cancer metastasis is conventionally classified into two mechanisms: single and collective cell migration. Fascin increases cancer metastasis by single cell migration via filopodia on the cell surface. However, the present study suggested that following FKD, TNBC cells lost filopodia and exhibited collective cell migration.

Mechanism and clinical use of botulinum neurotoxin in head and facial region.

PURPOSE: Botulinum neurotoxin (BoNT) is a biological toxin produced by Clostridium botulinum. BoNT is a potent toxin extensively used in therapeutic interventions. This review provides an updated overview of the mechanisms of action and clinical applications of BoNT in head and facial region. STUDY SELECTION: MEDLINE/PubMed searches were conducted using the terms "botulinum neurotoxin" and "dentistry" along with a combination of other related terms. In addition, studies were manually selected from reference lists of the selected articles. RESULTS: The Food and Drug Administration in the United States initially approved BoNT to treat strabismus, blepharospasm, and hemifacial spasms. The use of BoNT in dermatology and cosmetics has been widely established and has created a revolution in these fields. Over the years, its applications in various medical specialties have expanded widely. Owing to its safety, efficacy, and long duration of action, it is well-accepted by patients. BoNT/A and BoNT/B are widely used in clinical practice. Several off-label uses of BoNT in the dental fraternity have yielded promising results. We have elaborated on the speculated mechanism of action, dosage, effective sites of injection, and adverse effects of each therapeutic application. The various clinical indications for BoNT include bruxism, myofascial pain, temporomandibular joint dislocation, hemifacial pain, orofacial dystonia, facial paralysis, chronic migraine, and trigeminal neuralgia. CONCLUSIONS: BoNT is a safe treatment that can be used effectively, provided that the clinician has adequate knowledge regarding the mechanism, injection techniques, and local and systemic side effects and that it is administered cautiously and purposefully.

Bisphosphonate type-dependent cell viability suppressive effects of carbon nanohorn-calcium phosphate-bisphosphonate nanocomposites.

In the process of bone metastasis, tumor cells spread to the bones to activate osteoclasts, which cause pathological bone resorption and destruction. Bisphosphonates (BPs) inhibit osteoclast activation to resorb bone, reducing bone pain and fracture. We previously developed a nanocomposite for potential localized treatment of bone metastasis by loading a BP compound, ibandronate, onto oxidized carbon nanohorns (OxCNHs), a next-generation drug carrier, using calcium phosphates (CaPs) as mediators to generate OxCNH-CaP-BP nanocomposites. The objective of the present study was to determine nanocomposite formation and biological properties of nanocomposites constructed from two BPs, zoledronate and pamidronate. In vitro tests using murine macrophages (RAW264.7 cells) and osteoclasts differentiated from RAW264.7 cells revealed that the resulting OxCNH-CaP-BP nanocomposites suppressed cell viability in a BP type-dependent manner and more effectively than OxCNHs or BPs alone. The mechanism for the potent and BP type-dependent suppression of cell viability by OxCNH-CaP-BP nanocomposites, based on their relative cellular uptake and reactive oxygen species generation, is also discussed. The present study supports the conclusions that BPs can be loaded onto OxCNHs using CaPs as mediators, and that OxCNH-CaP-BP nanocomposites are putative medicines for localized treatment of metastatic bone destruction.

Evaluation of Clinical and Immunohistochemical Factors Relating to Melanoma Metastasis: Potential Roles of Nestin and Fascin in Melanoma.

For melanoma treatment, an early diagnosis and a complete resection of the primary tumor is essential. In addition, detection of factors that may be related to metastasis is indispensable. A total of 30 Japanese patients with Stage I or II melanoma, diagnosed according to the classification of the American Joint Committee on Cancer, are included in this study. Clinical background (sex, onset age, primary tumor area, existence of remaining cancer cells at the resected tissue margin, and treatment after the primary surgery) and immunohistochemical staining (Nestin and Fascin) on the resected tissue were examined to detect factors statistically related to metastasis. The analysis result has shown that older onset age and positive immunohistochemical expressions of Nestin and Fascin are statistically related to metastasis. To facilitate meticulous observation of Nestin and Fascin expression at different timing (e.g., onset and metastasis), double immunofluorescence staining was performed. Nestin is a class VI intermediate filament protein, initially detected in neural stem cells. Fascin is an actin-bundling protein which regulates cell adhesion, migration and invasion. Nestin and Fascin are suggested to relate to melanoma metastasis, however, the potential role of Fascin is controversial. Analysis of variations in Fascin expression detected in this study may contribute to further investigations concerning potential roles of Fascin for progression of melanoma. This is the first study to report double immunofluorescent staining of Nestin and Fascin in melanoma. Nestin and Fascin double-positive melanoma cells were detected.

Fascin expression persists with fibronectin in embryonic rat hepatoblasts.

Both fascin and fibronectin are known to play important roles in cell adhesion and migration. They are noted as tumor markers or inhibiting target for tumor treatment. In this study, embryonic rat livers were obtained to examine the expression of fascin and fibronectin during liver development. Then, the effect of fibronectin on fascin expression was investigated. At embryonic day (ED) 10.5, when the foregut endoderm began to form the liver bud and spread into the septum transversum, fibrous extracellular matrix was observed between the space where the liver bud and the septum transversum merged. At ED11.5, fibronectin was observed surrounding the cluster of fascin-positive hepatoblasts. At ED13.5, hematopoietic cells emerged and both fibronectin and fascin expression started to decline. Fascin and fibronectin appeared temporarily and disappeared by ED 14.5. Their expression was chronologically synchronized. Subsequently, the effect of fibronectin on fascin was examined by cultivation of hepatoblasts that were isolated from the ED13.5 rat liver. As a result, with fibronectin, fascin was positive in most hepatoblasts, although, without fibronectin, fascin expression was remarkably declined. Presently, there are few studies about the relationship between fascin and fibronectin. Our findings suggest that fibronectin could regulate fascin expression in rat hepatoblasts.

Peripherally Administered Botulinum Toxin Type A Localizes Bilaterally in Trigeminal Ganglia of Animal Model.

Peripheral nerve injury leads to sensory ganglion hyperexcitation, which increases neurotransmitter release and neuropathic pain. Botulinum toxin type A (BoNT/A) regulates pain transmission by reducing neurotransmitter release, thereby attenuating neuropathic pain. Despite multiple studies on the use of BoNT/A for managing neuropathic pain in the orofacial region, its exact mechanism of transport remains unclear. In this study, we investigated the effects of BoNT/A in managing neuropathic pain in two different animal models and its transport mechanism in the trigeminal nerve. Intraperitoneal administration of cisplatin induced bilateral neuropathic pain in the orofacial region, reducing the head withdrawal threshold to mechanical stimulation. Unilateral infraorbital nerve constriction (IONC) also reduced the ipsilateral head withdrawal threshold to mechanical stimulation. Unilateral peripheral administration of BoNT/A to the rat whisker pad attenuated cisplatin-induced pain behavior bilaterally. Furthermore, contralateral peripheral administration of BoNT/A attenuated neuropathy-induced behavior caused by IONC. We also noted the presence of BoNT/A in the blood using the mouse bioassay. In addition, the Alexa Fluor-488-labeled C-terminal half of the heavy chain of BoNT/A (BoNT/A-Hc) was localized in the neurons of the bilateral trigeminal ganglia following its unilateral administration. These findings suggest that axonal and hematogenous transport are involved in the therapeutic effects of peripherally administered BoNT/A in the orofacial region.

Environmental survey of Methicillin-Resistant Staphylococci in a Hospital in Japan.

We examined the hospital-wide incidence of methicillin-resistant Staphylococcus contamination in a hospital environment to predict the risk of the nosocomial spread of infection. Samples were also taken different surfaces and medical equipment in a general hospital ward and a staff station. The isolates were identified bacterial strains and analyzed by PCR for detection of the mecA gene and staphylococcal cassette chromosome mec (SCCmec) types (I-V). Overall, out of 146 isolates that were screened, 15.7% of the samples in the hospital wards were contaminated with Staphylococcus aureus and 74.7% were isolated with coagulase-negative Staphylococci (CNS). The methicillin-resistant mecA gene was detected in all oxacillin-resistant S. aureus, and 89% of oxacillin-resistant CNS was identified as methicillin-resistant S. aureus (MRSA) and MRCNS respectively. All S. aureus and CNS from the hospital wards with MRSA patients were detected as MRSA and MRCNS. A widespread distribution of MRSA and MRCNS was detected in the Cuff. The majority of the MRSA and MRCNS isolates in this study were SCCmec type V, which are a community-acquired infection type. The increased incidence and prevalence of community-acquired MRSA and MRCNS, as well as hospital-acquired MRSA, should be recognized as serious healthcare problems.

Fascin-1 is associated with recurrence in solitary fibrous tumor/hemangiopericytoma.

Fascin-1, an actin-bundling protein, is associated with poor prognosis in patients with various types of human carcinoma. However, research is limited on the role of fascin-1 in sarcoma. Solitary fibrous tumor (SFT) and hemangiopericytoma (HPC) are rare sarcomas derived from the mesenchyme. Although the prognosis of SFT/HPC is generally favorable, fatalities are possible with repeated recurrence and distant metastasis. The current study included a total of 20 Japanese patients, who were diagnosed with SFT/HPC and underwent surgery at Kochi University Hospital from January 2000 to December 2019. The statistical relationship between recurrence and the following variables were examined: Sex, age of onset, tumor origin, tumor size, necrosis, mitosis ≥1/10 high power field (HPF; magnification, x400), Ki-67 >5% and Fascin-1. A significant association was determined between recurrence and necrosis, mitosis ≥1/10 HPF (magnification, x400), Ki-67 >5%, and Fascin-1 ≥'strongly positive' (P<0.05). The results demonstrated that Fascin-1 immunostaining may be a highly effective and useful evaluation factor for predicting poor prognosis in patients with SFT/HPC, a fatal sarcoma of humans.

Chromosomal-scale de novo genome assemblies of Cynomolgus Macaque and Common Marmoset.

Cynomolgus macaque (Macaca fascicularis) and common marmoset (Callithrix jacchus) have been widely used in human biomedical research. Long-standing primate genome assemblies used the human genome as a reference for ordering and orienting the assembled fragments into chromosomes. Here we performed de novo genome assembly of these two species without any human genome-based bias observed in the genome assemblies released earlier. We assembled PacBio long reads, and the resultant contigs were scaffolded with Hi-C data, which were further refined based on Hi-C contact maps and alternate de novo assemblies. The assemblies achieved scaffold N50 lengths of 149 Mb and 137 Mb for cynomolgus macaque and common marmoset, respectively. The high fidelity of our assembly is also ascertained by BAC-end concordance in common marmoset. Our assembly of cynomolgus macaque outperformed all the available assemblies of this species in terms of contiguity. The chromosome-scale genome assemblies produced in this study are valuable resources for non-human primate models and provide an important baseline in human biomedical research.

Elizabethkingia anophelis, an emerging pathogen, inhibits RAW 264.7 macrophage function.

Elizabethkingia anophelis is a pathogen that can cause a life-threatening infection in immunocompromised patients. The first case of E. anophelis infection was reported in 2013; subsequently, an increase in its incidence has been reported globally. Additionally, a mortality rate of more than 30% was observed in the US outbreak of 2015. To date, the pathogenic mechanisms underlying E. anophelis infection, such as toxin production, remain unclear. Since tissue macrophages act as the first line of defense against pathogens, in the present study the interactions between E. anophelis and a macrophage-like cell line RAW 264.7 were examined. Although E. anophelis showed no cytotoxicity toward RAW 264.7 macrophages, the infection inhibited LPS-induced morphological changes and activation of differentiation markers for the polarization of RAW 264.7 macrophages toward an M1-like phenotype. However, when the cell contact was restricted using Transwell inserts or bacterial culture supernatants were used instead of live bacteria, no such inhibition was observed. Moreover, it was shown that E. anophelis evaded phagocytosis. Overall, the results suggest that E. anophelis infection inhibits the differentiation of RAW 264.7 macrophages to a pro-inflammatory phenotype in a contact-dependent manner.

Ibandronate-Loaded Carbon Nanohorns Fabricated Using Calcium Phosphates as Mediators and Their Effects on Macrophages and Osteoclasts.

Carbon nanohorns (CNHs), a type of nanocarbon, have been studied for the application of drug delivery systems (DDSs) because they are easily functionalized, support bone regeneration, can be used to perform photohyperthermia, have low toxicity, and are easily phagocytosed by macrophages. To take advantage of these features of CNHs, we developed a DDS for the local treatment of bone metastasis by loading the antibone resorption drug ibandronate (IBN) onto CNHs. The poor adsorption of IBN onto CNHs due to the weak hydrophilic-hydrophobic interaction was overcome by using calcium phosphates (CaPs) as mediators. In the fabrication process, we used oxidized CNH (OxCNH), which is less hydrophobic, onto which IBN was coprecipitated with CaP from a labile supersaturated CaP solution. OxCNH-CaP-IBN composite nanoparticles exerted stronger cell-suppressive effects than OxCNH and IBN in both murine macrophages (RAW264.7 cells) and osteoclasts (differentiated from RAW264.7 cells). OxCNH-CaP-IBN composite nanoparticles were efficiently phagocytosed by macrophage cells, where they specifically accumulated in lysosomes. The stronger cell-suppressive effects were likely due to intracellular delivery of IBN, i.e., the release of IBN from OxCNH-CaP-IBN composite nanoparticles via dissociation of CaP in the acidic environment of lysosomes. Our findings suggest that OxCNH-CaP-IBN composite nanoparticles are potentially useful for the local treatment of metastatic bone destruction.

The impact of bronchial artery embolisation on the quality of life of patients with haemoptysis: a prospective observational study.

OBJECTIVES: Patients with haemoptysis often experience daily physical and mental impairment. Bronchial artery embolisation is among the first-line treatment options used worldwide; however, no evidence exists regarding the health-related quality of life (HRQoL) after bronchial artery embolisation. Therefore, this study aimed to evaluate the effects of bronchial artery embolisation on the HRQoL of patients with haemoptysis. METHODS: We prospectively enrolled 61 consecutive patients who visited our hospital from July 2017 to August 2018 and received bronchial artery embolisation for haemoptysis. The primary outcome was the HRQoL evaluated using the Short Form Health Survey, which contains physical and mental components, before and after bronchial artery embolisation. The secondary outcomes were procedural success, complications, and recurrence-free survival rate at 6 months. RESULTS: The mean age of the patients was 69 years (range, 31-87 years). The procedural success rate was 98%. No major complications occurred. The recurrence-free survival rate estimated using the Kaplan-Meier analysis at 6 months after bronchial artery embolisation was 91.8% (95% confidence interval, 91.1-92.5%). Compared with the pre-treatment scores, the physical and mental scores were significantly improved at 6 months after bronchial artery embolisation (p < 0.05). CONCLUSION: Bronchial artery embolisation improved the HRQoL of patients with haemoptysis. KEY POINTS: • Bronchial artery embolisation improved the HRQoL of patients with haemoptysis. • Vessel dilation on computed tomography and systemic artery-pulmonary artery direct shunting on angiography were the most common abnormalities. • The recurrence-free survival rate estimated using the Kaplan-Meier analysis at 6 months after bronchial artery embolisation was 91.8%.

Analysis of a plasmid encoding botulinum neurotoxin type G gene in Clostridium argentinense.

Clostridium argentinense produces botulinum neurotoxin type G (BoNT/G). We sequenced and analyzed the plasmid harboring the bont/G gene, designated pCAG, in C. argentinense strain 2740. The pCAG consisted of 140,070 bp containing the bont/G gene cluster. Although this gene cluster showed high similarities in its DNA sequence and ORF arrangement to those of other bont gene clusters, the other regions of the plasmid did not. A phylogenetic study suggested that pCAG had a unique evolutionary history compared with other clostridial bont-harboring plasmids. This suggests that pCAG is possibly a novel type of plasmid expressing the bont/G gene in C. argentinense.

Recurrence of Solitary Fibrous Tumor/Hemangiopericytoma Could Be Predicted by Ki-67 Regardless of Its Origin.

Since the discovery of the NAB2-STAT6 gene fusion in 2013, solitary fibrous tumor (SFT) and hemangiopericytoma (HPC) have been considered the same disease. STAT6 nuclear stain is approved as a highly sensitive and specific marker to diagnose SFT/HPC from other tumors with similar histology. As the next step, detection of fusion variants that may predict clinical malignancy of SFT/HPC has been attempted. However, no fusion variants with a clear relation to malignancy have been identified. In this study, the clinical and histological backgrounds of 23 Japanese patients diagnosed with SFT/HPC from 2000 to 2019 at Kochi University Hospital were examined to identify factors potentially related to recurrence. A significant relationship to recurrence was detected for mitosis ≥ 1/10 HPF (400×), necrosis, and Ki-67>5%. These findings indicate that a deliberate investigation of histological features such as mitosis and necrosis is crucial for the clinical observation of SFT/ HPC patients. In addition, Ki-67 was revealed to be a useful parameter to predict recurrence in SFT/HPC patients.

Vibrio alginolyticus VepA Induces Lysosomal Membrane Permeability and Cathepsin-Independent Cell Death.

The bacterium Vibrio alginolyticus, an opportunistic pathogen in humans, has a type III secretion system (T3SS) that is responsible for its cytotoxicity toward eukaryotic cells. The effector of T3SS that is responsible for the cytotoxicity had not been identified. Here we demonstrate that VepA, a homolog of the T3SS effector in V. parahaemolyticus, is required for cytotoxicity in V. alginolyticus. VepA induces lysosomal membrane permeabilization, and it allows the leakage of only small molecules into the cytosol. Our findings revealed that VepA induces cathepsin-independent cell death in mammalian cells. The ferrous ion, one of the small molecules in the lysosome contents, appears to be involved in the cell death caused by V. alginolyticus VepA.