Antigen-Specific Adaptive Immunity to SARS-CoV-2 in Acute COVID-19 and Associations with Age and Disease Severity.

Limited knowledge is available on the relationship between antigen-specific immune responses and COVID-19 disease severity. We completed a combined examination of all three branches of adaptive immunity at the level of SARS-CoV-2-specific CD4+ and CD8+ T cell and neutralizing antibody responses in acute and convalescent subjects. SARS-CoV-2-specific CD4+ and CD8+ T cells were each associated with milder disease. Coordinated SARS-CoV-2-specific adaptive immune responses were associated with milder disease, suggesting roles for both CD4+ and CD8+ T cells in protective immunity in COVID-19. Notably, coordination of SARS-CoV-2 antigen-specific responses was disrupted in individuals ≥ 65 years old. Scarcity of naive T cells was also associated with aging and poor disease outcomes. A parsimonious explanation is that coordinated CD4+ T cell, CD8+ T cell, and antibody responses are protective, but uncoordinated responses frequently fail to control disease, with a connection between aging and impaired adaptive immune responses to SARS-CoV-2.

Interleukin-4 downregulates transcription factor BCL6 to promote memory B cell selection in germinal centers.

Germinal center (GC)-derived memory B cells (MBCs) are critical for humoral immunity as they differentiate into protective antibody-secreting cells during re-infection. GC formation and cellular interactions within the GC have been studied in detail, yet the exact signals that allow for the selection and exit of MBCs are not understood. Here, we showed that IL-4 cytokine signaling in GC B cells directly downregulated the transcription factor BCL6 via negative autoregulation to release cells from the GC program and to promote MBC formation. This selection event required additional survival cues and could therefore result in either GC exit or death. We demonstrate that both increasing IL-4 bioavailability or limiting IL-4 signaling disrupted MBC selection stringency. In this way, IL-4 control of BCL6 expression serves as a tunable switch within the GC to tightly regulate MBC selection and affinity maturation.

Bcl-6 is the nexus transcription factor of T follicular helper cells via repressor-of-repressor circuits.

T follicular helper (TFH) cells are a distinct type of CD4+ T cells that are essential for most antibody and B lymphocyte responses. TFH cell regulation and dysregulation is involved in a range of diseases. Bcl-6 is the lineage-defining transcription factor of TFH cells and its activity is essential for TFH cell differentiation and function. However, how Bcl-6 controls TFH biology has largely remained unclear, at least in part due to the intrinsic challenges of connecting repressors to gene upregulation in complex cell types with multiple possible differentiation fates. Multiple competing models were tested here by a series of experimental approaches to determine that Bcl-6 exhibits negative autoregulation and controls pleiotropic attributes of TFH differentiation and function, including migration, costimulation, inhibitory receptors and cytokines, via multiple repressor-of-repressor gene circuits.

The Chromatin Regulator Mll1 Supports T Follicular Helper Cell Differentiation by Controlling Expression of Bcl6, LEF-1, and TCF-1.

T follicular helper (TFH) cells are essential for developing protective Ab responses following vaccination. Greater understanding of the genetic program leading to TFH differentiation is needed. Chromatin modifications are central in the control of gene expression. However, detailed knowledge of how chromatin regulators (CRs) regulate differentiation of TFH cells is limited. We screened a large short hairpin RNA library targeting all known CRs in mice and identified the histone methyltransferase mixed lineage leukemia 1 (Mll1) as a positive regulator of TFH differentiation. Loss of Mll1 expression reduced formation of TFH cells following acute viral infection or protein immunization. In addition, expression of the TFH lineage-defining transcription factor Bcl6 was reduced in the absence of Mll1. Transcriptomics analysis identified Lef1 and Tcf7 as genes dependent on Mll1 for their expression, which provides one mechanism for the regulation of TFH differentiation by Mll1. Taken together, CRs such as Mll1 substantially influence TFH differentiation.

Bcl6-Mediated Transcriptional Regulation of Follicular Helper T cells (TFH).

Follicular helper T cells (TFH) are essential B cell-help providers in the formation of germinal centers (GCs), affinity maturation of GC B cells, differentiation of high-affinity antibody-producing plasma cells, and production of memory B cells. The transcription factor (TF) B cell lymphoma 6 (Bcl6) is at the center of gene regulation in TFH biology, including differentiation and function, but how Bcl6 does this, and what additional TFs contribute, remain complex questions. This review focuses on advances in our understanding of Bcl6-mediated gene regulation of TFH functions, and the modulation of TFH by other TFs. These advances may have important implications in deciphering how repressor TFs can regulate many immunological cell types. An improved understanding of TFH biology will likely provide insights into biomedically relevant diseases.

P21-activated kinase 2 is essential in maintenance of peripheral Foxp3+ regulatory T cells.

The p21-activated kinase 2 (Pak2), an effector molecule of the Rho family GTPases Rac and Cdc42, regulates diverse functions of T cells. Previously, we showed that Pak2 is required for development and maturation of T cells in the thymus, including thymus-derived regulatory T (Treg) cells. However, whether Pak2 is required for the functions of various subsets of peripheral T cells, such as naive CD4 and helper T-cell subsets including Foxp3+ Treg cells, is unknown. To determine the role of Pak2 in CD4 T cells in the periphery, we generated inducible Pak2 knockout (KO) mice, in which Pak2 was deleted in CD4 T cells acutely by administration of tamoxifen. Temporal deletion of Pak2 greatly reduced the number of Foxp3+ Treg cells, while minimally affecting the homeostasis of naive CD4 T cells. Pak2 was required for proliferation and Foxp3 expression of Foxp3+ Treg cells upon T-cell receptor and interleukin-2 stimulation, differentiation of in vitro induced Treg cells, and activation of naive CD4 T cells. Together, Pak2 is essential in maintaining the peripheral Treg cell pool by providing proliferation and maintenance signals to Foxp3+ Treg cells.

Pak2 Links TCR Signaling Strength to the Development of Regulatory T Cells and Maintains Peripheral Tolerance.

Although significant effort has been devoted to understanding the thymic development of Foxp3(+) regulatory T cells (Tregs), the precise signaling pathways that govern their lineage commitment still remain enigmatic. Our findings show a novel role for the actin cytoskeletal remodeling protein, p21-activated kinase 2 (Pak2), in Treg development and homeostasis. The absence of Pak2 in T cells resulted in a marked reduction in both thymus- and peripherally derived Tregs, accompanied by the development of spontaneous colitis in Pak2-deficient mice. Additionally, Pak2 was required for the proper differentiation of in vitro-induced Tregs as well as maintenance of Tregs. Interestingly, Pak2 was necessary for generating the high-affinity TCR- and IL-2-mediated signals that are required by developing Tregs for their lineage commitment. These findings provide novel insight into how developing thymocytes translate lineage-specific high-affinity TCR signals to adopt the Treg fate, and they further posit Pak2 as an essential regulator for this process.

Field-effect modulation of the thermoelectric characteristics of silicon nanowires on plastic substrates.

In this study, we demonstrate the substantial enhancement of the thermoelectric power factors of silicon nanowires (SiNWs) on plastic substrates achievable by field-effect modulation. The Seebeck coefficient and electrical conductivity are adjusted by varying the charge carrier concentration via electrical modulation with a gate voltage in the 0 to ±5 range, thus enhancing the power factors from 2.08 to 935 µW K-2 m-1) for n-type SiNWs, and from 453 to 944 µW K-2 m-1) for p-type SiNWs. The electrically modulated thermoelectric characteristics of SiNWs are analyzed and discussed.

Ameliorating effects of HX106N, a water-soluble botanical formulation, on Aß25-35-induced memory impairment and oxidative stress in mice.

It is well-established that amyloid ß (Aß)-induced oxidative stress plays a crucial role in Alzheimer's disease (AD) and its cognitive deficits. HX106N is a water-soluble extract prepared from a mixture of the plants Dimocarpus longan, Liriope platyphylla, Salvia miltiorrhiza, and Gastrodia elata. These ingredients are traditionally used in various plant-based medicines for the treatment of neurological disease. In this study, we examined the effects of HX106N on memory impairment and oxidative stress caused by the intracerebroventricular injection of Aß25-35 peptide in mice. For one week prior to Aß25-35 peptide injection and 8 d after, mice were given oral HX106N. HX106N treatment reversed the Aß25-35-mediated decrease in alternation percentage and latency time in the Y-maze and passive avoidance tests. Mice treated with HX106N showed decreased levels of thiobarbituric acid reactive substances (TBARS), a lipid peroxidation marker. Quantitative reverse transcription polymerase chain reaction (RT-PCR) demonstrated that HX106 treatment increased levels of heme oxygenase-1 (HO-1) in the hippocampus of Aß25-35-injected mice, while having little effect on the expression of tumor necrosis factor (TNF)-α and interleukin (IL)-1ß. In the murine hippocampal neuronal cell line HT22, HX106N was found to upregulate HO-1 expression at the RNA and protein levels as well as to protect cells from glutamate-induced oxidative stress. Taken together, our data suggest that HX106N may potentially act as a preventive and/or therapeutic agent for AD.

Cytokines in Follicular Helper T Cell Biology in Physiologic and Pathologic Conditions.

Follicular helper T cells (Tfh) play a crucial role in generating high-affinity antibodies (Abs) and establishing immunological memory. Cytokines, among other functional molecules produced by Tfh, are central to germinal center (GC) reactions. This review focuses on the role of cytokines, including IL-21 and IL-4, in regulating B cell responses within the GC, such as differentiation, affinity maturation, and plasma cell development. Additionally, this review explores the impact of other cytokines like CXCL13, IL-10, IL-9, and IL-2 on GC responses and their potential involvement in autoimmune diseases, allergies, and cancer. This review highlights contributions of Tfh-derived cytokines to both protective immunity and immunopathology across a spectrum of diseases. A deeper understanding of Tfh cytokine biology holds promise for insights into biomedical conditions.

Transcriptional regulation of Tfh dynamics and the formation of immunological synapses.

Inside germinal centers (GCs), antigen-specific B cells rely on precise interactions with immune cells and strategic localization between the dark and light zones to clonally expand, undergo affinity maturation, and differentiate into long-lived plasma cells or memory B cells. Follicular helper T (Tfh) cells, the key gatekeepers of GC-dependent humoral immunity, exhibit remarkable dynamic positioning within secondary lymphoid tissues and rely on intercellular interactions with antigen-presenting cells (APCs) during their differentiation and execution of B-cell-facilitating functions within GCs. In this review, we briefly cover the transcriptional regulation of Tfh cell differentiation and function and explore the molecular mechanisms governing Tfh cell motility, their interactions with B cells within GCs, and the impact of their dynamic behavior on humoral responses.

The role of cGAMP via the STING pathway in modulating germinal center responses and CD4 T cell differentiation.

Germinal center (GC) responses are essential for establishing protective, long-lasting immunity through the differentiation of GC B cells (BGC) and plasma cells (BPC), along with the generation of antigen-specific antibodies. Among the various pathways influencing immune responses, the STING (Stimulator of Interferon Genes) pathway has emerged as significant, especially in innate immunity, and extends its influence to adaptive responses. In this study, we examined how the STING ligand cGAMP can modulate these key elements of the adaptive immune response, particularly in enhancing GC reactions and the differentiation of BGC, BPC, and follicular helper T cells (TFH). Employing in vivo models, we evaluated various antigens and the administration of cGAMP in Alum adjuvant, investigating the differentiation of BGC, BPC, and TFH cells, along with the production of antigen-specific antibodies. cGAMP enhances the differentiation of BGC and BPC, leading to increased antigen-specific antibody production. This effect is shown to be type I Interferon-dependent, with a substantial reduction in BPC frequency upon interferon (IFN)-ß blockade. Additionally, cGAMP's influence on TFH differentiation varies over time, which may be critical for refining vaccine strategies. The findings elucidate a complex, antigen-specific influence of cGAMP on T and B cell responses, providing insights that could optimize vaccine efficacy.

PG201 downregulates the production of nitrite by upregulating heme oxygenase-1 expression through the control of phosphatidylinositol 3-kinase and NF-E2-related factor 2.

PG201 is an ethanol extract prepared from a specially designed botanical formulation and has previously been shown to contain strong anti-arthritic activities by controlling inflammation and cartilage destruction in two animal models [1,2]. In the present study, we evaluated the effects of PG201 on the expression of heme oxygenase-1 (HO-1). The treatment of Raw264.7 cells (a murine macrophage cell line) and bone marrow-derived macrophages (BMDMs) with PG201 increased the protein and RNA levels of HO-1. The results from a reporter plasmid assay indicated that PG201 induced HO-1 promoter activity through the stress response element present in the two enhancers of the HO-1 promoter. The treatment of cells with PG201 increased the total amount and the nuclear level of NF-E2-related factor 2 (Nrf2). Protein analysis using BMDMs from Nrf2 knockout mice showed that Nrf2 was necessary for the PG201-mediated induction of HO-1 expression. The PG201-mediated induction of these anti-oxidative stress factors was inhibited by a specific inhibitor of phosphatidylinositol 3-kinase (PI3K), but not by inhibitors of p38, ERK and JNK mitogen-activated protein kinases. Furthermore, the results from an experiment involving a specific siRNA and chemical inhibitors for HO-1 showed that the PG201-mediated increase of the HO-1 protein contributed to the suppression of inducible nitric oxide synthase (iNOS) and nitrite production stimulated by lipopolysaccharide. Taken together, these results suggest that PG201 activates Nrf2 through the PI3K signal transduction pathway, increases the expression of HO-1, and subsequently decreases the production of iNOS and nitrite, eventually exerting anti-inflammatory activities.

Length-dependent thermoelectric characteristics of silicon nanowires on plastics in a relatively low temperature regime in ambient air.

We report on the thermoelectric characteristics of p-type silicon nanowires (NWs) on plastics in the relatively low temperature regime below 47 °C, and for temperature differences of less than 10 K in ambient air. Thermal profile images are utilized to directly determine the temperature difference in the NWs generated by Joule heating in air. The Seebeck coefficient of the NWs increases from 294 to 414 µV K(-1) as the NW length varies from 40 to 280 µm. For a temperature difference of 7 K, the maximal Seebeck voltage can be estimated to be 2.7 mV for NWs with a length of 280 µm. In contrast, the output power is maximized for NWs length of 240 µm. The maximized output power obtained experimentally in this study is 2.1 pW at a temperature difference of 6 K. The thermoelectric characteristics are analyzed and discussed.

The effects of care management on depression treatment in a psychiatric clinic: a randomized controlled trial.

OBJECTIVE: This study aims to examine whether care management has an effect on adherence to depression treatment in a psychiatric clinic in Korea. METHODS: Fifty-seven patients with depression aged 60 years or over participated in the study. They were all low-income patients screened in the community and treated in a psychiatric clinic. The study design was a double-blind randomized controlled trial. The patients were randomly assigned to intervention (n = 29) or usual care (n = 28) groups. Intervention patients received depression care management for 6 months. Primary endpoint was an increase in remission rate as assessed using the 17-item Hamilton Depression Rating Scale score at 6 months. Secondary endpoints included improvement in treatment adherence, improvement in health-related quality of life, and a reduction in feelings of hopelessness. RESULTS: Patients in the care management intervention group showed a higher remission rate than those in the usual care group (55% vs. 29%, p = 0.0421). Intervention patients were significantly more likely to adhere to the treatment (59% vs. 18%, p = 0.0016). The hopelessness score at the 6-month assessment was significantly lower in the intervention group than the usual care group (23.5 vs. 25.7, p = 0.0443). However, there was not a significant group difference in the quality of life. CONCLUSIONS: We found that care management not only contributed to reducing depressive symptoms in geriatric patients suffering from depression but also increased the treatment adherence rate, which in turn increased the remission rate. Care management intervention is both feasible and effective in psychiatric clinics in Korea.

A case of acute motor and sensory axonal neuropathy following hepatitis a infection.

Acute motor and sensory axonal neuropathy (AMSAN) are recently described subtypes of Guillain-Barre syndrome characterized by acute onset of distal weakness, loss of deep tendon reflexes, and sensory symptoms. A 21-yr-old male was transferred to our hospital due to respiration difficulties and progressive weakness. In laboratory findings, immunoglobulin M antibodies against hepatitis A were detected in blood and cerebrospinal fluid. The findings of motor nerve conduction studies showed markedly reduced amplitudes of compound muscle action potentials in bilateral peroneal, and posterior tibial nerves, without evidence of demyelination. Based on clinical features, laboratory findings, and electrophysiologic investigation, the patient was diagnosed the AMSAN following acute hepatitis A viral infection. The patient was treated with intravenous immunoglobulin and recovered slowly. Clinicians should consider this rare but a serious case of AMSAN following acute hepatitis A infection.

Korean Red Ginseng Induced Cardioprotection against Myocardial Ischemia in Guinea Pig.

This study was designed to evaluate the protective effect of Korean red ginseng (KRG) against ischemia/reperfusion (I/R) injury in isolated guinea pig heart. KRG has been shown to possess various ginsenosides, which are the major components of Panax ginseng. These components are known naturally occurring compounds with beneficial effects and free radical scavenging activity. The heart was induced to ischemia for 60 min, followed by 120 min reperfusion. The hearts were randomly allocated into five groups (n=8 for each group): normal control (N/C), KRG control, I/R control, 250 mg/kg KRG group and 500 mg/kg KRG group. KRG significantly increased hemodynamics parameters such as aortic flow, coronary flow and cardiac output. Moreover, KRG significantly increased left ventricular systolic pressure (LVSP), the maximal rate of contraction (+dP/dtmax) and maximal rate of relaxation (-dP/dtmax). Also, treatment of KRG ameliorated electrocardiographic index such as the QRS, QT and RR intervals. Moreover, KRG significantly suppressed the lactate dehydrogenase, creatine kinase-MB fraction and cardiac troponin I and ameliorated the oxidative stress markers such as malondialdehyde and glutathione. KRG was standardized through ultra performance liquid chromatograph analysis for its major ginsenosides. Taken together, KRG has been shown to prevent cardiac injury by normalizing the biochemical and oxidative stress.

Single-cell and spatial sequencing application in pathology.

Traditionally, diagnostic pathology uses histology representing structural alterations in a disease's cells and tissues. In many cases, however, it is supplemented by other morphology-based methods such as immunohistochemistry and fluorescent in situ hybridization. Single-cell RNA sequencing (scRNA-seq) is one of the strategies that may help tackle the heterogeneous cells in a disease, but it does not usually provide histologic information. Spatial sequencing is designed to assign cell types, subtypes, or states according to the mRNA expression on a histological section by RNA sequencing. It can provide mRNA expressions not only of diseased cells, such as cancer cells but also of stromal cells, such as immune cells, fibroblasts, and vascular cells. In this review, we studied current methods of spatial transcriptome sequencing based on their technical backgrounds, tissue preparation, and analytic procedures. With the pathology examples, useful recommendations for pathologists who are just getting started to use spatial sequencing analysis in research are provided here. In addition, leveraging spatial sequencing by integration with scRNA-seq is reviewed. With the advantages of simultaneous histologic and single-cell information, spatial sequencing may give a molecular basis for pathological diagnosis, improve our understanding of diseases, and have potential clinical applications in prognostics and diagnostic pathology.

IL-4 downregulates BCL6 to promote memory B cell selection in germinal centers.

Germinal center (GC)-derived memory B cells (MBCs) are critical for humoral immunity as they differentiate into protective antibody-secreting cells during re-infection. GC formation and cellular interactions within the GC have been studied in detail, yet the exact signals that allow for the selection and exit of MBCs are not understood. Here, we show that IL-4 signaling in GC B cells directly downregulates BCL6 via negative autoregulation to release cells from the GC program and promote MBC formation. This selection event requires additional survival cues and can therefore result in either GC exit or death. We demonstrate that both increasing IL-4 bioavailability or limiting IL-4 signaling disrupt MBC selection stringency. In this way, IL-4 control of BCL6 expression serves as a tunable switch within the GC to tightly regulate MBC selection and affinity maturation.

Transcriptional programming of CD4+ TRM differentiation in viral infection balances effector- and memory-associated gene expression.

After resolution of infection, T cells differentiate into long-lived memory cells that recirculate through secondary lymphoid organs or establish residence in tissues. In contrast to CD8+ tissue-resident memory T cells (TRM), the developmental origins and transcriptional regulation of CD4+ TRM remain largely undefined. Here, we investigated the phenotypic, functional, and transcriptional profiles of CD4+ TRM in the small intestine (SI) responding to acute viral infection, revealing a shared gene expression program and chromatin accessibility profile with circulating TH1 and the progressive acquisition of a mature TRM program. Single-cell RNA sequencing identified heterogeneity among established CD4+ TRM, which were predominantly located in the lamina propria, and revealed a population of cells that coexpressed both effector- and memory-associated genes, including the transcriptional regulators Blimp1, Id2, and Bcl6. TH1-associated Blimp1 and Id2 and TFH-associated Bcl6 were required for early TRM formation and development of a mature TRM population in the SI. These results demonstrate a developmental relationship between TH1 effector cells and the establishment of early TRM, as well as highlighted differences in CD4+ versus CD8+ TRM populations, providing insights into the mechanisms underlying the origins, differentiation, and persistence of CD4+ TRM in response to viral infection.