Memory B Cells and Memory T Cells Induced by SARS-CoV-2 Booster Vaccination or Infection Show Different Dynamics and Responsiveness to the Omicron Variant.

Although the immunological memory produced by BNT162b2 vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been well studied and established, further information using different racial cohorts is necessary to understand the overall immunological response to vaccination. We evaluated memory B and T cell responses to the severe acute respiratory syndrome coronavirus 2 spike protein before and after the third booster using a Japanese cohort. Although the Ab titer against the spike receptor-binding domain (RBD) decreased significantly 8 mo after the second vaccination, the number of memory B cells continued to increase, whereas the number of memory T cells decreased slowly. Memory B and T cells from unvaccinated infected patients showed similar kinetics. After the third vaccination, the Ab titer increased to the level of the second vaccination, and memory B cells increased at significantly higher levels before the booster, whereas memory T cells recovered close to the second vaccination levels. In memory T cells, the frequency of CXCR5+CXCR3+CCR6- circulating follicular Th1 was positively correlated with RBD-specific Ab-secreting B cells. For the response to variant RBDs, although 60-80% of memory B cells could bind to the omicron RBD, their avidity was low, whereas memory T cells show an equal response to the omicron spike. Thus, the persistent presence of memory B and T cells will quickly upregulate Ab production and T cell responses after omicron strain infection, which prevents severe illness and death due to coronavirus disease 2019.

Regulation of activated microglia and macrophages by systemically administered DNA/RNA heteroduplex oligonucleotides.

Microglial activation followed by recruitment of blood-borne macrophages into the central nervous system (CNS) aggravates neuroinflammation. Specifically, in multiple sclerosis (MS) as well as in experimental autoimmune encephalomyelitis (EAE), a rodent model of MS, activated microglia and macrophages (Mg/Mφ) promote proinflammatory responses and expand demyelination in the CNS. However, a potent therapeutic approach through the systemic route for regulating their functions has not yet been developed. Here, we demonstrate that a systemically injected DNA/RNA heteroduplex oligonucleotide (HDO), composed of an antisense oligonucleotide (ASO) and its complementary RNA, conjugated to cholesterol (Chol-HDO) distributed more efficiently to demyelinating lesions of the spinal cord in EAE mice with significant gene silencing than the parent ASO. Importantly, systemic administration of Cd40-targeting Chol-HDO improved clinical signs of EAE with significant downregulation of Cd40 in Mg/Mφ. Furthermore, we successfully identify that macrophage scavenger receptor 1 (MSR1) is responsible for the uptake of Chol-HDO by Mg/Mφ of EAE mice. Overall, our findings demonstrate the therapeutic potency of systemically administered Chol-HDO to regulate activated Mg/Mφ in neuroinflammation.

Porencephaly in a fetus and HANAC in her father: variable expression of COL4A1 mutation.

COL4A1-associated disorders encompass a wide range of hereditary vasculopathy, including porencephaly and HANAC (adult-onset hemorrhagic stroke with cerebral aneurysm and retinal arterial tortuosity, renal cysts, and thenar muscle cramp). It remains elusive whether or not porencephaly and HANAC are molecularly distinctive disorders due to different classes of mutations. We report on a girl with porencephaly and an episode of microangiopathic hemolysis in infancy and her father with HANAC, both of whom had a heterozygous missense mutation of COL4A1 (c.3715G>A, p.G1239R). The current observation implies phenotypic diversities of COL4A1 mutations.

Embolic stroke during apixaban therapy for left atrial appendage thrombus.

Left atrial appendage (LAA) thrombus is associated with atrial fibrillation (AF) and is a powerful predictor of cardiogenic thromboembolism. Warfarin is an established anticoagulant therapy for patients with LAA thrombus to prevent thromboembolic complications. Apixaban is superior to warfarin in the prevention of thromboembolic complications in patients with AF, and there are case reports showing apixaban-associated resolution of LAA thrombus; however, the efficacy and safety of apixaban for the treatment of LAA thrombus remains unproven. Here we report a patient who experienced embolic stroke while taking apixaban for the treatment of LAA thrombus. Thrombolysis therapy was initiated at the onset of stroke and the patient recovered remarkably. Apixaban is known to make thrombi mobile and/or fragile by shifting the coagulation/fibrinolysis balance to a relative predominance of fibrinolytic activity; therefore, it is necessary to monitor for thromboembolic complications after the initiation of apixaban for the treatment of pre-existing LAA thrombus.

T cells in the brain inflammation.

The immune system is deeply involved in autoimmune diseases of the central nervous system (CNS), such as multiple sclerosis, N-methyl-d-aspartate (NMDA) receptor encephalitis, and narcolepsy. Additionally, the immune system is involved in various brain diseases including cerebral infarction and neurodegenerative diseases such as Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS). In particular, reports related to T cells are increasing. T cells may also play important roles in brain deterioration and dementia that occur with aging. Our understanding of the role of immune cells in the context of the brain has been greatly improved by the use of acute ischemic brain injury models. Additionally, similar neural damage and repair events are shown to occur in more chronic brain neurodegenerative brain diseases. In this review, we focus on the role of T cells, including CD4+ T cells, CD8+ T cells and regulatory T cells (Tregs) in cerebral infarction and neurodegenerative diseases.

Anti-human-TIGIT agonistic antibody ameliorates autoimmune diseases by inhibiting Tfh and Tph cells and enhancing Treg cells.

T cells play important roles in autoimmune diseases, but it remains unclear how to optimally manipulate them. We focused on the T cell immunoreceptor with Ig and ITIM domains (TIGIT), a coinhibitory molecule that regulates and is expressed in T cells. In autoimmune diseases, the association between TIGIT-expressing cells and pathogenesis and the function of human-TIGIT (hu-TIGIT) signalling modification have not been fully elucidated. Here we generated anti-hu-TIGIT agonistic monoclonal antibodies (mAbs) and generated hu-TIGIT knock-in mice to accurately evaluate the efficacy of mAb function. Our mAb suppressed the activation of CD4+ T cells, especially follicular helper T and peripheral helper T cells that highly expressed TIGIT, and enhanced the suppressive function of naïve regulatory T cells. These results indicate that our mAb has advantages in restoring the imbalance of T cells that are activated in autoimmune diseases and suggest potential clinical applications for anti-hu-TIGIT agonistic mAbs as therapeutic agents.

In Vitro Generation of Brain Regulatory T Cells by Co-culturing With Astrocytes.

Regulatory T cells (Tregs) are normally born in the thymus and activated in secondary lymphoid tissues to suppress immune responses in the lymph node and at sites of inflammation. Tregs are also resident in various tissues or accumulate in damaged tissues, which are now called tissue Tregs, and contribute to homeostasis and tissue repair by interacting with non-immune cells. We have shown that Tregs accumulate in the brain during the chronic phase in a mouse cerebral infarction model, and these Tregs acquire the characteristic properties of brain Tregs and contribute to the recovery of neurological damage by interacting with astrocytes. However, the mechanism of tissue Treg development is not fully understood. We developed a culture method that confers brain Treg characteristics in vitro. Naive Tregs from the spleen were activated and efficiently amplified by T-cell receptor (TCR) stimulation in the presence of primary astrocytes. Furthermore, adding IL-33 and serotonin could confer part of the properties of brain Tregs, such as ST2, peroxisome proliferator-activated receptor γ (PPARγ), and serotonin receptor 7 (Htr7) expression. Transcriptome analysis revealed that in vitro generated brain Treg-like Tregs (induced brain Tregs; iB-Tregs) showed similar gene expression patterns as those in in vivo brain Tregs, although they were not identical. Furthermore, in Parkinson's disease models, in which T cells have been shown to be involved in disease progression, iB-Tregs infiltrated into the brain more readily and ameliorated pathological symptoms more effectively than splenic Tregs. These data indicate that iB-Tregs contribute to our understanding of brain Treg development and could also be therapeutic for inflammatory brain diseases.

Systemic DNA/RNA heteroduplex oligonucleotide administration for regulating the gene expression of dorsal root ganglion and sciatic nerve.

Neuropathic pain, a heterogeneous condition, affects 7%-10% of the general population. To date, efficacious and safe therapeutic approaches remain limited. Antisense oligonucleotide (ASO) therapy has opened the door to treat spinal muscular atrophy, with many ongoing clinical studies determining its therapeutic utility. ASO therapy for neuropathic pain and peripheral nerve disease requires efficient gene delivery and knockdown in both the dorsal root ganglion (DRG) and sciatic nerve, key tissues for pain signaling. We previously developed a new DNA/RNA heteroduplex oligonucleotide (HDO) technology that achieves highly efficient gene knockdown in the liver. Here, we demonstrated that intravenous injection of HDO, comprising an ASO and its complementary RNA conjugated to α-tocopherol, silences endogenous gene expression more than 2-fold in the DRG, and sciatic nerve with higher potency, efficacy, and broader distribution than ASO alone. Of note, we observed drastic target suppression in all sizes of neuronal DRG populations by in situ hybridization. Our findings establish HDO delivery as an investigative and potentially therapeutic platform for neuropathic pain and peripheral nerve disease.

DNA/RNA heteroduplex oligonucleotide technology for regulating lymphocytes in vivo.

Manipulating lymphocyte functions with gene silencing approaches is promising for treating autoimmunity, inflammation, and cancer. Although oligonucleotide therapy has been proven to be successful in treating several conditions, efficient in vivo delivery of oligonucleotide to lymphocyte populations remains a challenge. Here, we demonstrate that intravenous injection of a heteroduplex oligonucleotide (HDO), comprised of an antisense oligonucleotide (ASO) and its complementary RNA conjugated to α-tocopherol, silences lymphocyte endogenous gene expression with higher potency, efficacy, and longer retention time than ASOs. Importantly, reduction of Itga4 by HDO ameliorates symptoms in both adoptive transfer and active experimental autoimmune encephalomyelitis models. Our findings reveal the advantages of HDO with enhanced gene knockdown effect and different delivery mechanisms compared with ASO. Thus, regulation of lymphocyte functions by HDO is a potential therapeutic option for immune-mediated diseases.

Cholesterol-functionalized DNA/RNA heteroduplexes cross the blood-brain barrier and knock down genes in the rodent CNS.

Achieving regulation of endogenous gene expression in the central nervous system (CNS) with antisense oligonucleotides (ASOs) administered systemically would facilitate the development of ASO-based therapies for neurological diseases. We demonstrate that DNA/RNA heteroduplex oligonucleotides (HDOs) conjugated to cholesterol or α-tocopherol at the 5' end of the RNA strand reach the CNS after subcutaneous or intravenous administration in mice and rats. The HDOs distribute throughout the brain, spinal cord and peripheral tissues and suppress the expression of four target genes by up to 90% in the CNS, whereas single-stranded ASOs conjugated to cholesterol have limited activity. Gene knockdown was observed in major CNS cell types and was greatest in neurons and microglial cells. Side effects, such as thrombocytopenia and focal brain necrosis, were limited by using subcutaneous delivery or by dividing intravenous injections. By crossing the blood-brain barrier more effectively, cholesterol-conjugated HDOs may overcome the limited efficacy of ASOs targeting the CNS without requiring intrathecal administration.

Intrathecal IgG Synthesis and Persistent Inflammation Are Associated with White Matter Lesions in HIV-negative Patients with Cryptococcal Meningoencephalitis.

Objective Cryptococcal meningoencephalitis (CM) causes significant morbidity and mortality in human immunodeficiency virus (HIV)-negative and HIV-positive populations. White matter lesions (WMLs) have been reported in both populations of CM patients; however, the mechanisms underlying WML formation remain unknown. We herein report the relationship between the intrathecal immune response and the development of WMLs in HIV-negative patients with CM. Methods Eleven consecutive HIV-negative patients with CM who presented at one of three emergency hospitals in Japan from April 2001 to March 2018 were enrolled. For all patients, we retrospectively assessed the relationships between clinical and laboratory information and the presence of WMLs. Results At presentation, 6 patients had WMLs on magnetic resonance imaging (MRI). The cerebrospinal fluid immunoglobulin G (CSF IgG) index was significantly higher in the patients with WMLs than in those without WMLs (mean, 1.34 vs. 0.70, p=0.017). The time from the symptom onset to initial neuroimaging was also significantly longer in the patients with WMLs than in those without WMLs (median, 31.5 vs. 7.0 days; p=0.008). The clinical outcome was comparable among the patients with and without WMLs. Conclusion In HIV-negative patients with CM, a persistent, aberrant immune response to Cryptococcus, such as intrathecal IgG synthesis, may induce WML formation.

Progression of bilateral internal carotid artery dissection during antiplatelet therapy.

Bilateral internal carotid artery dissection (ICAD) is a rare but important cause of stroke in young adults. Anticoagulant and/or antiplatelet agents are usually recommended for stroke prevention;however, such treatments remain highly controversial, and there are inadequate data to compare the efficacy of anticoagulation and antiplatelet therapy. We herein report the case of 30-year-old man presenting with progressive bilateral ICAD during antiplatelet treatment. This report suggests the possibility that intramural hematomas are enlarged by antiplatelet and anticoagulant agents and draws attention to the medications associated with ICAD.

Chronic inflammatory demyelinating polyradiculoneuropathy in a patient with Crohn's disease.

Crohn's disease (CD) is a chronic inflammatory disorder of the gastrointestinal tract that is frequently accompanied by systemic complications. Neuropathologies have not been well investigated as extraintestinal manifestations of CD. We herein report the case of a 36-year-old man with CD who presented with progressive weakness and numbness. A neurological examination and the results of a nerve conduction study and a sural nerve biopsy led to a diagnosis of chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). Plasma exchanges were initially effective; however, the effects gradually declined starting 10 days after the plasma exchange (PE). These results suggest that humoral factors may play an important role in CIDP associated with CD.

Spinal epidural abscess caused by bacteroides fragilis group after dilation and curettage for incomplete abortion.

Spinal epidural abscess (SEA) is a rare infection complicated in patients who have some risk factors such as injection-drug use, diabetes mellitus, and several illnesses. However, no case of SEA associated with abortion has been reported. Here we report a case of SEA in a 30-year-old woman after dilation and curettage for incomplete abortion. The diagnosis of SEA was done by MRI and pus was drained after the cervical discectomy. Bacteroides fragilis group was cultured from the aspirated pus sample. The patient responded to surgical drainage and antibiotics.

Regulation of angiogenesis in the bone marrow of myelodysplastic syndromes transforming to overt leukaemia.

To investigate the regulatory mechanisms of angiogenesis in the development of myelodysplastic syndromes (MDS) and its progression to overt leukaemia (OL), bone marrow samples from control, paired samples from MDS patients before and after transformation to OL (MDS --> OL) and de novo acute myeloid leukaemia (AML) were analysed. Immunohistochemical staining showed a significant increase of bone marrow microvascular density (MVD) in MDS and de novo AML compared with controls. Surprisingly, in MDS, MVD significantly decreased upon transformation to OL, which was also significantly lower than the MVD of de novo AML. This evidence was strengthened by the pattern of angiogenic mediator gene expression, confirming the importance of various angiogenic mediators including vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), tumour necrosis factor alpha (TNFalpha), hepatocyte growth factor (HGF) and the angiopoietin family of mediators (Ang-1 and Ang-2) as well as the receptors for angiogenic mediators, such as VEGF receptor 2 (VEGFR2) and the tyrosine kinase receptor, TIE2. By contrast, the anti-angiogenic mediator, transforming growth factor-beta (TGFbeta) exhibited significantly higher expression in the bone marrow of MDS --> OL, indicating the importance of this cytokine as the suppressive factor of angiogenesis in MDS. These findings indicate that the bone marrow microenvironment in MDS --> OL and de novo AML differs remarkably, suggesting the different efficacy of anti-angiogenic therapy between de novo AML and leukaemia secondary to MDS.