CGG repeat expansion in LRP12 in amyotrophic lateral sclerosis.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder characterized by the degeneration of motor neurons. Although repeat expansion in C9orf72 is its most common cause, the pathogenesis of ALS isn't fully clear. In this study, we show that repeat expansion in LRP12, a causative variant of oculopharyngodistal myopathy type 1 (OPDM1), is a cause of ALS. We identify CGG repeat expansion in LRP12 in five families and two simplex individuals. These ALS individuals (LRP12-ALS) have 61-100 repeats, which contrasts with most OPDM individuals with repeat expansion in LRP12 (LRP12-OPDM), who have 100-200 repeats. Phosphorylated TDP-43 is present in the cytoplasm of iPS cell-derived motor neurons (iPSMNs) in LRP12-ALS, a finding that reproduces the pathological hallmark of ALS. RNA foci are more prominent in muscle and iPSMNs in LRP12-ALS than in LRP12-OPDM. Muscleblind-like 1 aggregates are observed only in OPDM muscle. In conclusion, CGG repeat expansions in LRP12 cause ALS and OPDM, depending on the length of the repeat. Our findings provide insight into the repeat length-dependent switching of phenotypes.

Insufficiency of ciliary cholesterol in hereditary Zellweger syndrome.

Primary cilia are antenna-like organelles on the surface of most mammalian cells that receive sonic hedgehog (Shh) signaling in embryogenesis and carcinogenesis. Cellular cholesterol functions as a direct activator of a seven-transmembrane oncoprotein called Smoothened (Smo) and thereby induces Smo accumulation on the ciliary membrane where it transduces the Shh signal. However, how cholesterol is supplied to the ciliary membrane remains unclear. Here, we report that peroxisomes are essential for the transport of cholesterol into the ciliary membrane. Zellweger syndrome (ZS) is a peroxisome-deficient hereditary disorder with several ciliopathy-related features and cells from these patients showed a reduced cholesterol level in the ciliary membrane. Reverse genetics approaches revealed that the GTP exchange factor Rabin8, the Rab GTPase Rab10, and the microtubule minus-end-directed kinesin KIFC3 form a peroxisome-associated complex to control the movement of peroxisomes along microtubules, enabling communication between peroxisomes and ciliary pocket membranes. Our findings suggest that insufficient ciliary cholesterol levels may underlie ciliopathies.

A case of meningoencephalitis caused by multisystem inflammatory syndrome in adult SARS-CoV-2 infection.

A 37-year-old woman was hospitalized with fever and consciousness disturbance. She showed systemic inflammation with stress cardiomyopathy. Brain computed tomography showed diffuse brain edema. Cerebrospinal fluid (CSF) findings revealed markedly elevated cerebrospinal fluid pressure with pleocytosis, elevated protein, and elevated interleukin 6. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nicking enzyme amplification reaction test using a nasopharyngeal swab was positive, and the patient was diagnosed with SARS-CoV-2 infection. From the negative result of the CSF SARS-CoV-2 polymerase chain reaction test and no findings of bacterial or viral infection, we diagnosed meningoencephalitis by multisystem inflammation syndrome in adults (MIS-A). Intravenous methylprednisolone pulse therapy improved her symptoms and brain edema. There have been no cases of MIS-A with meningoencephalitis, and no initial treatment strategy has been established, especially in emergency cases of suspected MIS-A. The present case suggested Early intravenous methylprednisolone pulse with anti-coronaviral therapies after the exclusion of bacterial infection would be useful in suspected MIS-A with emergent meningoencephalitis cases.

Geriatric nutrition risk index predicts prolonged post-stroke dysphagia in acute ischemic stroke.

BACKGROUND: Post-stroke dysphagia (PSD) is a common complication after stroke. Malnutrition inhibits stroke recovery and is associated with stroke mortality. However, no studies have investigated the effects of nutritional state at admission on prolonged PSD. METHODS: We retrospectively analyzed ischemic stroke patients in our institute from January 2018 to December 2020. Swallowing function was assessed using the Food Oral Intake Scale; prolonged PSD was defined as levels 1-3 at 14 days after admission. The Geriatric Nutritional Risk Index (GNRI) was used to assess nutritional risks, which were classified as follows: >98, no nutritional risk; 92-98, mild nutritional risk; 82-92, moderate nutritional risk; and <82, severe nutritional risk. The association between GNRI and prolonged PSD was assessed. RESULTS: Of 580 patients (median age, 81 years; male, 53%), prolonged PSD was detected in 117 patients. Patients with severe dysphagia had older age, higher pre-stroke modified Rankin Scale score, lower GNRI, and higher National Institutes of Health Stroke Scale score. Logistic regression analysis revealed that lower GNRI was independently associated with prolonged PSD (continuous value; adjusted odds ratio [OR] 1.03, 95% confidence interval [CI] 1.00-1.05). In addition, when "severe" and "moderate" nutritional risk was analyzed as a single class, moderate or severe nutritional risk (GNRI < 92) was independently associated with prolonged PSD (adjusted OR 2.50, 95% CI 1.29-4.87), compared with no nutritional risk patients (GNRI > 98). CONCLUSIONS: In acute ischemic stroke, lower GNRI at admission was independently associated with prolonged PSD, suggesting that GNRI at admission might identify patients at risk of prolonged PSD.

YAP is essential for tissue tension to ensure vertebrate 3D body shape.

Vertebrates have a unique 3D body shape in which correct tissue and organ shape and alignment are essential for function. For example, vision requires the lens to be centred in the eye cup which must in turn be correctly positioned in the head. Tissue morphogenesis depends on force generation, force transmission through the tissue, and response of tissues and extracellular matrix to force. Although a century ago D'Arcy Thompson postulated that terrestrial animal body shapes are conditioned by gravity, there has been no animal model directly demonstrating how the aforementioned mechano-morphogenetic processes are coordinated to generate a body shape that withstands gravity. Here we report a unique medaka fish (Oryzias latipes) mutant, hirame (hir), which is sensitive to deformation by gravity. hir embryos display a markedly flattened body caused by mutation of YAP, a nuclear executor of Hippo signalling that regulates organ size. We show that actomyosin-mediated tissue tension is reduced in hir embryos, leading to tissue flattening and tissue misalignment, both of which contribute to body flattening. By analysing YAP function in 3D spheroids of human cells, we identify the Rho GTPase activating protein ARHGAP18 as an effector of YAP in controlling tissue tension. Together, these findings reveal a previously unrecognised function of YAP in regulating tissue shape and alignment required for proper 3D body shape. Understanding this morphogenetic function of YAP could facilitate the use of embryonic stem cells to generate complex organs requiring correct alignment of multiple tissues.

A novel CDK-independent function of p27Kip1 in preciliary vesicle trafficking during ciliogenesis.

p27Kip1, a member of the Cip/Kip family of cyclin-dependent kinase (CDK) inhibitors, is now known as a multifunctional protein that plays crucial roles in cell architecture and migration by regulating rearrangements of the actin cytoskeleton and microtubules. The intracellular level of p27Kip1 is increased by anti-proliferative stimuli, such as mitogen deprivation and contact inhibition, which also induce formation of primary cilia, microtubule-based membranous organelles that protrude from the cell surface. However, it remains unknown whether p27Kip1 is associated with ciliogenesis. Here, we have generated p27Kip1-knockout hTERT-immortalized human retinal pigment epithelial cells, and found that ciliogenesis is almost completely disrupted in p27Kip1-knockout cells. The defect of ciliogenesis is rescued by the exogenous expression of wild-type p27Kip1 and, surprisingly, its 86-140 amino acid region, which is neither responsible for CDK inhibition nor remodeling of the actin cytoskeleton and microtubules. Moreover, transmission electron microscopy and immunofluorescence analyses reveal that p27Kip1 abrogation impairs one of the earliest events of ciliogenesis, docking of the Ehd1-associated preciliary vesicles to the distal appendages of the basal body. Our findings identify a novel CDK-independent function of p27Kip1 in primary cilia formation.

PLK1-mediated phosphorylation of WDR62/MCPH2 ensures proper mitotic spindle orientation.

Primary microcephaly (MCPH) is an autosomal recessive disorder characterized by congenital reduction of head circumference. Here, we identified compound heterozygous mutations c.731 C > T (p.Ser 244 Leu) and c.2413 G > T (p.Glu 805 X) in the WDR62/MCPH2 gene, which encodes the mitotic centrosomal protein WDR62, in two siblings in a Japanese family with microcephaly using whole-exome sequencing. However, the molecular and cellular pathology of microcephaly caused by WDR62/MCPH2 mutation remains unclear. To clarify the physiological role of WDR62, we used the CRISPR/Cas9 system and single-stranded oligonucleotides as a point-mutation-targeting donor to generate human cell lines with knock-in of WDR62/MCPH2 c.731 C > T (p.Ser 244 Leu) missense mutation. In normal metaphase, the mitotic spindle forms parallel to the substratum to ensure symmetric cell division, while WDR62/MCPH2-mutated cells exhibited a randomized spindle orientation caused by the impaired astral microtubule assembly. It was shown that a mitotic kinase, Polo-like kinase 1 (PLK1), is required for the maintenance of spindle orientation through astral microtubule development. In this study, we demonstrated that WDR62 is a PLK1 substrate that is phosphorylated at Ser 897, and that this phosphorylation at the spindle poles promotes astral microtubule assembly to stabilize spindle orientation. Our findings provide insights into the role of the PLK1-WDR62 pathway in the maintenance of proper spindle orientation.

Albatross/FBF1 contributes to both centriole duplication and centrosome separation.

The centrosome is a small but important organelle that participates in centriole duplication, spindle formation, and ciliogenesis. Each event is regulated by key enzymatic reactions, but how these processes are integrated remains unknown. Recent studies have reported that ciliogenesis is controlled by distal appendage proteins such as FBF1, also known as Albatross. However, the precise role of Albatross in the centrosome cycle, including centriole duplication and centrosome separation, remains to be determined. Here, we report a novel function for Albatross at the proximal ends of centrioles. Using Albatross monospecific antibodies, full-length constructs, and siRNAs for rescue experiments, we found that Albatross mediates centriole duplication by recruiting HsSAS-6, a cartwheel protein of centrioles. Moreover, Albatross participates in centrosome separation during mitosis by recruiting Plk1 to residue S348 of Albatross after its phosphorylation. Taken together, our results show that Albatross is a novel protein that spatiotemporally integrates different aspects of centrosome function, namely ciliogenesis, centriole duplication, and centrosome separation.

Updated summary of genome editing technology in human cultured cells linked to human genetics studies.

Current deep-sequencing technology provides a mass of nucleotide variations associated with human genetic disorders to accelerate the identification of causative mutations. To understand the etiology of genetic disorders, reverse genetics in human cultured cells is a useful approach for modeling a disease in vitro. However, gene targeting in human cultured cells is difficult because of their low activity of homologous recombination. Engineered endonucleases enable enhancement of the local activation of DNA repair pathways at the human genome target site to rewrite the desired sequence, thereby efficiently generating disease-modeling cultured cell clones. These edited cells can be used to explore the molecular functions of a causative gene product to uncover the etiological mechanisms. The correction of mutations in patient cells using genome editing technology could contribute to the development of unique gene therapies. This technology can also be applied to screening causative mutations. Rare genetic disorders and non-exonic mutation-caused diseases remain frontier in the field of human genetics as it is difficult to validate whether the extracted nucleotide variants are mutation or polymorphism. When isogenic human cultured cells with a candidate variant reproduce the pathogenic phenotypes, it is confirmed that the variant is a causative mutation.

Coordinated regulation of the dorsal-ventral and anterior-posterior patterning of Xenopus embryos by the BTB/POZ zinc finger protein Zbtb14.

During early vertebrate embryogenesis, bone morphogenetic proteins (BMPs) belonging to the transforming growth factor-ß (TGF-ß) family of growth factors play a central role in dorsal-ventral (DV) patterning of embryos, while other growth factors such as Wnt and fibroblast growth factor (FGF) family members regulate formation of the anterior-posterior (AP) axis. Although the establishment of body plan is thought to require coordinated formation of the DV and AP axes, the mechanistic details underlying this coordination are not well understood. Here, we show that a Xenopus homologue of zbtb14 plays an essential role in the regulation of both DV and AP patterning during early Xenopus development. We show that overexpression of Zbtb14 promotes neural induction and inhibits epidermal differentiation, thereby regulating DV patterning. In addition, Zbtb14 promotes the formation of posterior neural tissue and suppresses anterior neural development. Consistent with this, knock-down experiments show that Zbtb14 is required for neural development, especially for the formation of posterior neural tissues. Mechanistically, Zbtb14 reduces the levels of phosphorylated Smad1/5/8 to suppress BMP signaling and induces an accumulation of ß-Catenin to promote Wnt signaling. Collectively, these results suggest that Zbtb14 plays a crucial role in the formation of DV and AP axes by regulating both the BMP and Wnt signaling pathways during early Xenopus embryogenesis.

Cilia play a role in breaking left-right symmetry of the sea urchin embryo.

Left-right asymmetry of bilaterian animals is established during early development. In mice, frogs and fishes, the ciliated left-right organizer plays an essential role in establishing bilateral asymmetry, and leftward flow of extracellular fluid generated by ciliary motion results in Nodal activity on the left side. However, H(+) /K(+) -ATPase activity is also involved in the determination of left-right asymmetry in a variety of animals, and it has been thought to be an ancestral mechanism in deuterostomes. In sea urchin, the determination of the left-right asymmetry based on H(+) /K(+) -ATPase activity was already clarified, but it remains to be uncovered whether ciliary motion is involved in the left-right asymmetry of the embryo. Here, we show evidence that ciliary motion is involved in the establishment of left-right asymmetry of sea urchin embryo. Furthermore, we show that the initial cilia generated on small micromeres during the early stage of embryogenesis may be involved in this process. These results suggest that the cilia-mediated mechanism for the determination of left-right asymmetry may be acquired at the base of the deuterostomes.

Cytoskeleton-related regulation of primary cilia shortening mediated by melanin-concentrating hormone receptor 1.

Primary cilia are specialized microtubule-based organelles. Their importance is highlighted by the gamut of ciliary diseases associated with various syndromes including diabetes and obesity. Primary cilia serve as signaling hubs through selective interactions with ion channels and conventional G-protein-coupled receptors (GPCRs). Melanin-concentrating hormone (MCH) receptor 1 (MCHR1), a key regulator of feeding, is selectively expressed in neuronal primary cilia in distinct regions of the mouse brain. We previously found that MCH acts on ciliary MCHR1 and induces cilia shortening through a Gi/o-dependent Akt pathway with no cell cycle progression. Many factors can participate in cilia length control. However, the mechanisms for how these molecules are relocated and coordinated to activate cilia shortening are poorly understood. In the present study, we investigated the role of cytoskeletal dynamics in regulating MCH-induced cilia shortening using clonal MCHR1-expressing hTERT-RPE1 cells. Pharmacological and biochemical approaches showed that cilia shortening mediated by MCH was associated with increased soluble cytosolic tubulin without changing the total tubulin amount. Enhanced F-actin fiber intensity was also observed in MCH-treated cells. The actions of various pharmacological agents revealed that coordinated actin machinery, especially actin polymerization, was required for MCHR1-mediated cilia shortening. A recent report indicated the existence of actin-regulated machinery for cilia shortening through GPCR agonist-dependent ectosome release. However, our live-cell imaging experiments showed that MCH progressively elicited cilia shortening without exclusion of fluorescence-positive material from the tip. Short cilia phenotypes have been associated with various metabolic disorders. Thus, the present findings may contribute toward better understanding of how the cytoskeleton is involved in the GPCR ligand-triggered cilia shortening with cell mechanical properties that underlies clinical manifestations such as obesity.

TALEN-mediated single-base-pair editing identification of an intergenic mutation upstream of BUB1B as causative of PCS (MVA) syndrome.

Cancer-prone syndrome of premature chromatid separation with mosaic variegated aneuploidy [PCS (MVA) syndrome] is a rare autosomal recessive disorder characterized by constitutional aneuploidy and a high risk of childhood cancer. We previously reported monoallelic mutations in the BUB1B gene (encoding BUBR1) in seven Japanese families with the syndrome. No second mutation was found in the opposite allele of any of the families studied, although a conserved BUB1B haplotype and a decreased transcript were identified. To clarify the molecular pathology of the second allele, we extended our mutational search to a candidate region surrounding BUB1B. A unique single nucleotide substitution, G > A at ss802470619, was identified in an intergenic region 44 kb upstream of a BUB1B transcription start site, which cosegregated with the disorder. To examine whether this is the causal mutation, we designed a transcription activator-like effector nuclease-mediated two-step single-base pair editing strategy and biallelically introduced this substitution into cultured human cells. The cell clones showed reduced BUB1B transcripts, increased PCS frequency, and MVA, which are the hallmarks of the syndrome. We also encountered a case of a Japanese infant with PCS (MVA) syndrome carrying a homozygous single nucleotide substitution at ss802470619. These results suggested that the nucleotide substitution identified was the causal mutation of PCS (MVA) syndrome.

Zinc-finger nuclease-mediated targeted insertion of reporter genes for quantitative imaging of gene expression in sea urchin embryos.

To understand complex biological systems, such as the development of multicellular organisms, it is important to characterize the gene expression dynamics. However, there is currently no universal technique for targeted insertion of reporter genes and quantitative imaging in multicellular model systems. Recently, genome editing using zinc-finger nucleases (ZFNs) has been reported in several models. ZFNs consist of a zinc-finger DNA-binding array with the nuclease domain of the restriction enzyme FokI and facilitate targeted transgene insertion. In this study, we successfully inserted a GFP reporter cassette into the HpEts1 gene locus of the sea urchin, Hemicentrotus pulcherrimus. We achieved this insertion by injecting eggs with a pair of ZFNs for HpEts1 with a targeting donor construct that contained ∼1-kb homology arms and a 2A-histone H2B-GFP cassette. We increased the efficiency of the ZFN-mediated targeted transgene insertion by in situ linearization of the targeting donor construct and cointroduction of an mRNA for a dominant-negative form of HpLig4, which encodes the H. pulcherrimus homolog of DNA ligase IV required for error-prone nonhomologous end joining. We measured the fluorescence intensity of GFP at the single-cell level in living embryos during development and found that there was variation in HpEts1 expression among the primary mesenchyme cells. These findings demonstrate the feasibility of ZFN-mediated targeted transgene insertion to enable quantification of the expression levels of endogenous genes during development in living sea urchin embryos.

Efficient TALEN construction and evaluation methods for human cell and animal applications.

Transcription activator-like effector nucleases (TALENs) have recently arisen as effective tools for targeted genome engineering. Here, we report streamlined methods for the construction and evaluation of TALENs based on the 'Golden Gate TALEN and TAL Effector Kit' (Addgene). We diminished array vector requirements and increased assembly rates using six-module concatemerization. We altered the architecture of the native TALEN protein to increase nuclease activity and replaced the final destination vector with a mammalian expression/in vitro transcription vector bearing both CMV and T7 promoters. Using our methods, the whole process, from initiating construction to completing evaluation directly in mammalian cells, requires only 1 week. Furthermore, TALENs constructed in this manner may be directly applied to transfection of cultured cells or mRNA synthesis for use in animals and embryos. In this article, we show genomic modification of HEK293T cells, human induced pluripotent stem cells, Drosophila melanogaster, Danio rerio and Xenopus laevis, using custom-made TALENs constructed and evaluated with our protocol. Our methods are more time efficient compared with conventional yeast-based evaluation methods and provide a more accessible and effective protocol for the application of TALENs in various model organisms.

Fatal Community-Acquired Clostridioides difficile Infection as a Cause of Listeria Meningitis: A Case Report.

A 77-year-old woman with a history of total gastrectomy was transferred to our hospital with complaints of fever and consciousness disturbance for five days. She had fever and consciousness disturbance with positive meningeal signs. Laboratory findings indicated an elevated inflammatory response and hypoalbuminemia, and computed tomography (CT) of the body indicated intestinal gas retention and mild ascites. Cerebrospinal fluid analysis revealed pleocytosis with elevated protein levels and a diagnosis of Listeria meningitis was made. Treatment with ampicillin/sulbactam was started, and her fever and consciousness disturbance resolved on day 2. However, on day 3, her fever and conscious disturbance deteriorated, and she went into shock subsequently. Laboratory findings revealed deteriorated inflammatory response and hypoalbuminemia. Body CT showed an obvious distended bowel loop and intestinal edema. A stool culture revealed positive Clostridioides difficile toxin B, and we diagnosed her with Clostridioides difficile infection (CDI). Although intravenous metronidazole was initiated, she died due to prolonged hypovolemic shock. We considered she had community-acquired CDI because her CDI emerged immediately after the initiation of antibiotics, symptom deterioration within 48 hours of admission, and abnormal abdominal CT findings at admission. Listeria meningitis can develop based on community-acquired CDI. Because CDI can have a very rapid and fatal course and is sometimes complicated by other infectious diseases, clinicians should pay attention to this complication.

In vivo CRISPR screening directly targeting testicular cells.

CRISPR-Cas9 short guide RNA (sgRNA) library screening is a powerful approach to understand the molecular mechanisms of biological phenomena. However, its in vivo application is currently limited. Here, we developed our previously established in vitro revival screening method into an in vivo one to identify factors involved in spermatogenesis integrity by utilizing sperm capacitation as an indicator. By introducing an sgRNA library into testicular cells, we successfully pinpointed the retinal degeneration 3 (Rd3) gene as a significant factor in spermatogenesis. Single-cell RNA sequencing (scRNA-seq) analysis highlighted the high expression of Rd3 in round spermatids, and proteomics analysis indicated that Rd3 interacts with mitochondria. To search for cell-type-specific signaling pathways based on scRNA-seq and proteomics analyses, we developed a computational tool, Hub-Explorer. Through this, we discovered that Rd3 modulates oxidative stress by regulating mitochondrial distribution upon ciliogenesis induction. Collectively, our screening system provides a valuable in vivo approach to decipher molecular mechanisms in biological processes.

An Infection Model for SARS-CoV-2 Using Rat Transplanted with hiPSC-Airway Epithelial Cells.

Investigating the infection mechanism of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the airway epithelium and developing effective defense strategies against infection are important. To achieve this, establishing appropriate infection models is crucial. Therefore, various in vitro models, such as cell lines and primary cultures, and in vivo models involving animals that exhibit SARS-CoV-2 infection and genetically humanized animals have been used as animal models. However, no animal model has been established that allows infection experiments with human cells under the physiological environment of airway epithelia. Therefore, we aimed to establish a novel animal model that enables infection experiments using human cells. Human induced pluripotent stem cell-derived airway epithelial cell-transplanted nude rats (hiPSC-AEC rats) were used, and infection studies were performed by spraying lentiviral pseudoviruses containing SARS-CoV-2 spike protein and the GFP gene on the tracheae. After infection, immunohistochemical analyses revealed the existence of GFP-positive-infected transplanted cells in the epithelial and submucosal layers. In this study, a SARS-CoV-2 infection animal model including human cells was established mimicking infection through respiration, and we demonstrated that the hiPSC-AEC rat could be used as an animal model for basic research and the development of therapeutic methods for human-specific respiratory infectious diseases.

Insufficiency of BUBR1, a mitotic spindle checkpoint regulator, causes impaired ciliogenesis in vertebrates.

Budding uninhibited by benzimidazole-related 1 (BUBR1) is a central molecule of the spindle assembly checkpoint. Germline mutations in the budding uninhibited by benzimidazoles 1 homolog beta gene encoding BUBR1 cause premature chromatid separation (mosaic variegated aneuploidy) [PCS (MVA)] syndrome, which is characterized by constitutional aneuploidy and a high risk of childhood cancer. Patients with the syndrome often develop Dandy-Walker complex and polycystic kidneys; implying a critical role of BUBR1 in morphogenesis. However, little is known about the function of BUBR1 other than mitotic control. Here, we report that BUBR1 is essential for the primary cilium formation, and that the PCS (MVA) syndrome is thus a novel ciliopathy. Morpholino knockdown of bubr1 in medaka fish also caused ciliary dysfunction characterized by defects in cerebellar development and perturbed left-right asymmetry of the embryo. Biochemical analyses demonstrated that BUBR1 is required for ubiquitin-mediated proteasomal degradation of cell division cycle protein 20 in the G0 phase and maintains anaphase-promoting complex/cyclosome-CDC20 homolog 1 activity that regulates the optimal level of dishevelled for ciliogenesis.

Steroid Rebound Phenomenon as a Cause of Delayed Cerebral Vasospasm in Post-Splenectomy Pneumococcal Meningitis: A Case Report.

Pneumococcal meningitis as an overwhelming post-splenectomy infection (OPSI) has a higher risk of neurological complications and is sometimes life-threatening. In acute pneumococcal meningitis, four days of dexamethasone is widely used for the prevention of neurological complications. Herein, we report a 68-year-old woman with the diagnosis of pneumococcal meningitis as OPSI. With adequate antibiotics and dexamethasone, her symptoms gradually improved. However, after dexamethasone withdrawal, her consciousness got worse and got into a coma. Brain magnetic resonance imaging revealed acute cerebral infarctions in the bilateral middle cerebral artery territory with multiple vascular stenoses and hydrocephalus. Vascular stenoses improved by follow-up, suggesting cerebral vasospasm. There were no suggestive findings of cerebral vasculitis. Follow-up cerebrospinal fluid analysis showed remained pleocytosis with no bacteria, which could not suggest meningitis recurrence. Since steroid therapy was rapidly withdrawn, we diagnosed that the cerebral vasospasm was due to the steroid rebound phenomenon. The steroid rebound phenomenon due to the excessive immune response to bacterial microstructures has been reported in pneumococcal meningitis. Especially, the present case was asplenia and the usual dexamethasone use would not adequately suppress the immune response to bacterial microstructures. Since pneumococcal meningitis as OPSI has a higher risk of neurological complications, clinicians should consider longer and more cautious steroid tapering.