Infection-induced plasmablasts are a nutrient sink that impairs humoral immunity to malaria.

Plasmodium parasite-specific antibodies are critical for protection against malaria, yet the development of long-lived and effective humoral immunity against Plasmodium takes many years and multiple rounds of infection and cure. Here, we report that the rapid development of short-lived plasmablasts during experimental malaria unexpectedly hindered parasite control by impeding germinal center responses. Metabolic hyperactivity of plasmablasts resulted in nutrient deprivation of the germinal center reaction, limiting the generation of memory B cell and long-lived plasma cell responses. Therapeutic administration of a single amino acid to experimentally infected mice was sufficient to overcome the metabolic constraints imposed by plasmablasts and enhanced parasite clearance and the formation of protective humoral immune memory responses. Thus, our studies not only challenge the current model describing the role and function of blood-stage Plasmodium-induced plasmablasts but they also reveal new targets and strategies to improve anti-Plasmodium humoral immunity.

The transcription factor Runx3 guards cytotoxic CD8+ effector T cells against deviation towards follicular helper T cell lineage.

Activated CD8+ T cells differentiate into cytotoxic effector (TEFF) cells that eliminate target cells. How TEFF cell identity is established and maintained is not fully understood. We found that Runx3 deficiency limited clonal expansion and impaired upregulation of cytotoxic molecules in TEFF cells. Runx3-deficient CD8+ TEFF cells aberrantly upregulated genes characteristic of follicular helper T (TFH) cell lineage, including Bcl6, Tcf7 and Cxcr5. Mechanistically, the Runx3-CBFß transcription factor complex deployed H3K27me3 to Bcl6 and Tcf7 genes to suppress the TFH program. Ablating Tcf7 in Runx3-deficient CD8+ TEFF cells prevented the upregulation of TFH genes and ameliorated their defective induction of cytotoxic genes. As such, Runx3-mediated Tcf7 repression coordinately enforced acquisition of cytotoxic functions and protected the cytotoxic lineage integrity by preventing TFH-lineage deviation.

Tcf1 and Lef1 transcription factors establish CD8(+) T cell identity through intrinsic HDAC activity.

The CD4(+) and CD8(+) T cell dichotomy is essential for effective cellular immunity. How individual T cell identity is established remains poorly understood. Here we show that the high-mobility group (HMG) transcription factors Tcf1 and Lef1 are essential for repressing CD4(+) lineage-associated genes including Cd4, Foxp3 and Rorc in CD8(+) T cells. Tcf1- and Lef1-deficient CD8(+) T cells exhibit histone hyperacetylation, which can be ascribed to intrinsic histone deacetylase (HDAC) activity in Tcf1 and Lef1. Mutation of five conserved amino acids in the Tcf1 HDAC domain diminishes HDAC activity and the ability to suppress CD4(+) lineage genes in CD8(+) T cells. These findings reveal that sequence-specific transcription factors can utilize intrinsic HDAC activity to guard cell identity by repressing lineage-inappropriate genes.

TCF-1 upregulation identifies early innate lymphoid progenitors in the bone marrow.

The cellular and molecular events that drive the early development of innate lymphoid cells (ILCs) remain poorly understood. We show that the transcription factor TCF-1 is required for the efficient generation of all known adult ILC subsets and their precursors. Using novel reporter mice, we identified a new subset of early ILC progenitors (EILPs) expressing high amounts of TCF-1. EILPs lacked efficient T and B lymphocyte potential but efficiently gave rise to NK cells and all known adult helper ILC lineages, indicating that they are the earliest ILC-committed progenitors identified so far. Our results suggest that upregulation of TCF-1 expression denotes the earliest stage of ILC fate specification. The discovery of EILPs provides a basis for deciphering additional signals that specify ILC fate.

LEF-1 and TCF-1 orchestrate T(FH) differentiation by regulating differentiation circuits upstream of the transcriptional repressor Bcl6.

Follicular helper T cells (T(FH) cells) are specialized effector CD4(+) T cells that help B cells develop germinal centers (GCs) and memory. However, the transcription factors that regulate the differentiation of T(FH) cells remain incompletely understood. Here we report that selective loss of Lef1 or Tcf7 (which encode the transcription factor LEF-1 or TCF-1, respectively) resulted in T(FH) cell defects, while deletion of both Lef1 and Tcf7 severely impaired the differentiation of T(FH) cells and the formation of GCs. Forced expression of LEF-1 enhanced T(FH) differentiation. LEF-1 and TCF-1 coordinated such differentiation by two general mechanisms. First, they established the responsiveness of naive CD4(+) T cells to T(FH) cell signals. Second, they promoted early T(FH) differentiation via the multipronged approach of sustaining expression of the cytokine receptors IL-6Rα and gp130, enhancing expression of the costimulatory receptor ICOS and promoting expression of the transcriptional repressor Bcl6.

TFH cells depend on Tcf1-intrinsic HDAC activity to suppress CTLA4 and guard B-cell help function.

Precise regulation of coinhibitory receptors is essential for maintaining immune tolerance without interfering with protective immunity, yet the mechanism underlying such a balanced act remains poorly understood. In response to protein immunization, T follicular helper (TFH) cells lacking Tcf1 and Lef1 transcription factors were phenotypically normal but failed to promote germinal center formation and antibody production. Transcriptomic profiling revealed that Tcf1/Lef1-deficient TFH cells aberrantly up-regulated CTLA4 and LAG3 expression, and treatment with anti-CTLA4 alone or combined with anti-LAG3 substantially rectified B-cell help defects by Tcf1/Lef1-deficient TFH cells. Mechanistically, Tcf1 and Lef1 restrain chromatin accessibility at the Ctla4 and Lag3 loci. Groucho/Tle corepressors, which are known to cooperate with Tcf/Lef factors, were essential for TFH cell expansion but dispensable for repressing coinhibitory receptors. In contrast, mutating key amino acids in histone deacetylase (HDAC) domain in Tcf1 resulted in CTLA4 derepression in TFH cells. These findings demonstrate that Tcf1-instrinsic HDAC activity is necessary for preventing excessive CTLA4 induction in protein immunization-elicited TFH cells and hence guarding their B-cell help function.

iNKT subsets differ in their developmental and functional requirements on Foxo1.

Invariant natural killer T (iNKT) cells play important roles in regulating immune responses. Based on cytokine profiling and key transcriptional factors, iNKT cells are classified into iNKT1, iNKT2, and iNKT17 subsets. However, whether the development and functions of these subsets are controlled by distinct mechanisms remains unclear. Here, we show that forkhead box protein O1 (Foxo1) promotes differentiation of iNKT1 and iNKT2 cells but not iNKT17 cells because of its distinct contributions to IL7R expression in these subsets. Nuclear Foxo1 is essential for Il7r expression in iNKT1 and iNKT2 cells at early stages of differentiation but is dispensable in iNKT17 cells. RORγt, instead of Foxo1, promotes IL7R expression in iNKT17 cells. Additionally, Foxo1 is required for the effector function of iNKT1 and iNKT2 cells but not iNKT17 cells. Cytoplasmic Foxo1 promotes activation of mTORC1 in iNKT1 and iNKT2 cells through inhibiting TSC1-TSC2 interaction, whereas it is dispensable for mTORC1 activation in iNKT17 cells. iNKT17 cells display distinct metabolic gene expression patterns from iNKT1 and iNKT2 cells that match their different functional requirements on Foxo1. Together, our results demonstrate that iNKT cell subsets differ in their developmental and functional requirements on Foxo1.

Theoretical Study on Zigzag Boron Nitride Nanowires.

In this work, two kinds of BN-nanowires (BNnws): a-BNnw and d-BNnw, respectively composed of azo (N-N) and diboron (B-B) bonds, are proposed with the aid of the first-principles simulations. Their structural stabilities are carefully verified from the energetics, lattice dynamics, and thermodynamic perspectives. Similar to the other common boron nitride polymorph, the a-BNnw and d-BNnw are semiconductors with relatively wide band gaps of 3.256 and 4.631 eV at the HSE06 level, respectively. The corresponding projected DOS patterns point out that their band edges are composed of different atomic species, which can help with the separation of their excitons. The band gaps can be manipulated monotonically by axial strains within the elastic ranges. The major charge carriers are electron holes. Significantly, a-BNnw possesses very high carrier mobilities around 0.44×104  cm2 V-1 s-1 .

Post-Quantum Secure Identity-Based Proxy Blind Signature Scheme on a Lattice.

Blind signatures have been widely applied when privacy preserving is required, and the delegation of blind signature rights and a proxy blind signature (Proxy-BS) become necessary when the signer cannot sign. Existing Proxy-BS schemes are based on traditional cryptographically hard problems, and they cannot resist quantum attacks. Moreover, most current Proxy-BS schemes depend on public key infrastructure (PKI), which leads to high certificate storage and management overhead. To simplify key management and resist quantum attacks, we propose a post-quantum secure identity-based proxy blind signature (ID-Proxy-BS) scheme on a lattice using a matrix cascade technique and lattice cryptosystem. Under the random oracle model (ROM), the security of the proposed scheme is proved. Security shows that the proposed scheme assures security against quantum attacks and satisfies the correctness, blindness, and unforgeability. In addition, we apply the ID-Proxy-BS scheme on a lattice to e-voting and propose a quantum-resistant proxy e-voting system, which is resistant to quantum attacks and achieves the efficiency of e-voting.

Research on Quantum-Attack-Resistant Strong Forward-Secure Signature Schemes.

The security of digital signatures depends significantly on the signature key. Therefore, to reduce the impact of leaked keys upon existing signatures and subsequent ones, a digital signature scheme with strong forward security could be an effective solution. Most existing strong forward-secure digital signature schemes rely on traditional cryptosystems, which cannot effectively resist quantum attacks. By introducing lattice-based delegation technology into the key-iteration process, a two-direction and lattice-based key-iteration algorithm with strong forward security is proposed. In the proposed algorithm, a unique key pair is assigned to the signer in every period. Based on the proposed algorithm, a strong forward-secure signature scheme is further put forward, which achieves resistance to quantum attacks. Performance analysis shows that under the security assumption of the SIS problem on the lattice, the proposed strong forward-secure signature scheme is existentially unforgeable under the random oracle model. Ultimately, based on the proposed strong forward-secure signature scheme, a remote identity-authentication scheme that is resistant to quantum attacks is proposed, ensuring post-quantum security in the user-authentication process.

Transfer learning based cascaded deep learning network and mask recognition for COVID-19.

The COVID-19 is still spreading today, and it has caused great harm to human beings. The system at the entrance of public places such as shopping malls and stations should check whether pedestrians are wearing masks. However, pedestrians often pass the system inspection by wearing cotton masks, scarves, etc. Therefore, the detection system not only needs to check whether pedestrians are wearing masks, but also needs to detect the type of masks. Based on the lightweight network architecture MobilenetV3, this paper proposes a cascaded deep learning network based on transfer learning, and then designs a mask recognition system based on the cascaded deep learning network. By modifying the activation function of the MobilenetV3 output layer and the structure of the model, two MobilenetV3 networks suitable for cascading are obtained. By introducing transfer learning into the training process of two modified MobilenetV3 networks and a multi-task convolutional neural network, the ImagNet underlying parameters of the network models are obtained in advance, which reduces the computational load of the models. The cascaded deep learning network consists of a multi-task convolutional neural network cascaded with these two modified MobilenetV3 networks. A multi-task convolutional neural network is used to detect faces in images, and two modified MobilenetV3 networks are used as the backbone network to extract the features of masks. After comparing with the classification results of the modified MobilenetV3 neural network before cascading, the classification accuracy of the cascading learning network is improved by 7%, and the excellent performance of the cascading network can be seen.

Cutting Edge: Tcf1 Instructs T Follicular Helper Cell Differentiation by Repressing Blimp1 in Response to Acute Viral Infection.

Differentiation of T follicular helper (TFH) cells is regulated by a complex transcriptional network, with mutually antagonistic Bcl6-Blimp1 as a core regulatory axis. It is well established that Tcf1 acts upstream of Bcl6 for its optimal induction to program TFH cell differentiation. In this study, we show that whereas genetic ablation of Tcf1 in mice greatly diminished TFH cells in response to viral infection, compound deletion of Blimp1 with Tcf1 restored TFH cell frequency, numbers, and generation of germinal center B cells. Aberrant upregulation of T-bet and Id2 in Tcf1-deficient TFH cells was also largely rectified by ablating Blimp1. Tcf1 chromatin immunoprecipitation sequencing in TFH cells identified two strong Tcf1 binding sites in the Blimp1 gene at a 24-kb upstream and an intron-3 element. Deletion of the intron-3 element, but not the 24-kb upstream element, compromised production of TFH cells. Our data demonstrate that Tcf1-mediated Blimp1 repression is functionally critical for safeguarding TFH cell differentiation.

FarpScusn: Fully Anonymous Routing Protocol with Self-Healing Capability in Unstable Sensor Networks.

Anonymous technology is an effective way for protecting users' privacy. Anonymity in sensor networks is to prevent the unauthorized third party from revealing the identities of the communication parties. While, in unstable wireless sensor networks, frequent topology changes often lead to route-failure in anonymous communication. To deal with the problems of anonymous route-failure in unstable sensor networks, in this paper we propose a fully anonymous routing protocol with self-healing capability in unstable sensor networks by constructing a new key agreement scheme and proposing an anonymous identity scheme. The proposed protocol maintains full anonymity of sensor nodes with the self-healing capability of anonymous routes. The results from the performance analysis show that the proposed self-healing anonymity-focused protocol achieves full anonymity of source nodes, destination nodes, and communication association.

Differential Requirements for Tcf1 Long Isoforms in CD8+ and CD4+ T Cell Responses to Acute Viral Infection.

In response to acute viral infection, activated naive T cells give rise to effector T cells that clear the pathogen and memory T cells that persist long-term and provide heightened protection. T cell factor 1 (Tcf1) is essential for several of these differentiation processes. Tcf1 is expressed in multiple isoforms, with all isoforms sharing the same HDAC and DNA-binding domains and the long isoforms containing a unique N-terminal ß-catenin-interacting domain. In this study, we specifically ablated Tcf1 long isoforms in mice, while retaining expression of Tcf1 short isoforms. During CD8+ T cell responses, Tcf1 long isoforms were dispensable for generating cytotoxic CD8+ effector T cells and maintaining memory CD8+ T cell pool size, but they contributed to optimal maturation of central memory CD8+ T cells and their optimal secondary expansion in a recall response. In contrast, Tcf1 long isoforms were required for differentiation of T follicular helper (TFH) cells, but not TH1 effectors, elicited by viral infection. Although Tcf1 short isoforms adequately supported Bcl6 and ICOS expression in TFH cells, Tcf1 long isoforms remained important for suppressing the expression of Blimp1 and TH1-associated genes and for positively regulating Id3 to restrain germinal center TFH cell differentiation. Furthermore, formation of memory TH1 and memory TFH cells strongly depended on Tcf1 long isoforms. These data reveal that Tcf1 long and short isoforms have distinct, yet complementary, functions and may represent an evolutionarily conserved means to ensure proper programming of CD8+ and CD4+ T cell responses to viral infection.

Hematopoietic and Leukemic Stem Cells Have Distinct Dependence on Tcf1 and Lef1 Transcription Factors.

Hematopoietic and leukemic stem cells (HSCs and LSCs) have self-renewal ability to maintain normal hematopoiesis and leukemia propagation, respectively. Tcf1 and Lef1 transcription factors are expressed in HSCs, and targeting both factors modestly expanded the size of the HSC pool due to diminished HSC quiescence. Functional defects of Tcf1/Lef1-deficient HSCs in multi-lineage blood reconstitution was only evident under competitive conditions or when subjected to repeated regenerative stress. These are mechanistically due to direct positive regulation of Egr and Tcf3 by Tcf1 and Lef1, and significantly, forced expression of Egr1 in Tcf1/Lef1-deficient HSCs restored HSC quiescence. In a preclinical CML model, loss of Tcf1/Lef1 did not show strong impact on leukemia initiation and progression. However, when transplanted into secondary recipients, Tcf1/Lef1-deficient LSCs failed to propagate CML. By induced deletion of Tcf1 and Lef1 in pre-established CML, we further demonstrated an intrinsic requirement for these factors in LSC self-renewal. When combined with imatinib therapy, genetic targeting of Tcf1 and Lef1 potently diminished LSCs and conferred better protection to the CML recipients. LSCs are therefore more sensitive to loss of Tcf1 and Lef1 than HSCs in their self-renewal capacity. The differential requirements in HSCs and LSCs thus identify Tcf1 and Lef1 transcription factors as novel therapeutic targets in treating hematological malignancies, and inhibition of Tcf1/Lef1-regulated transcriptional programs may thus provide a therapeutic window to eliminate LSCs with minimal side effect on normal HSC functions.

Numb and Numbl act to determine mammary myoepithelial cell fate, maintain epithelial identity, and support lactogenesis.

Mammary epithelium is comprised of an inner layer of luminal epithelial cells and an outer layer of contractile myoepithelial cells with mesenchymal properties. These two compartments interact throughout mammary morphogenesis to form branching ducts during puberty and terminate in secretory alveoli during lactation. It is not known how the myoepithelial cell lineage is specified, nor how signals in myoepithelial cells contribute to lactogenesis. Here, we show that Numb and Numbl are enriched in mammary myoepithelial cells, with their expression peaking during pregnancy. We use conditional Numb- and Numbl-knockout mouse models to demonstrate that loss of Numb/Numbl compromised the myoepithelial layer and expanded the luminal layer, led epithelial cells to undergo epithelial-to-mesenchymal transition, and resulted in lactation failure as a result of abnormal alveolar formation during pregnancy. Numb and Numbl function via repression of the Notch signaling pathway and of the p53-p21 axis during mammary gland development. These findings highlight the importance of Numb and Numbl in the control of myoepithelial cell fate determination, epithelial identity, and lactogenesis.-Zhang Y., Li, F., Song, Y., Sheng, X., Ren, F., Xiong, K., Chen, L., Zhang, H., Liu, D., Lengner, C. J., Xue, L., Yu, Z. Numb and Numbl act to determine mammary myoepithelial cell fate, maintain epithelial identity, and support lactogenesis.

Enhancing the potency of lithospermate B for inhibiting Na+/K+-ATPase activity by forming transition metal ion complexes.

AIM: To determine whether replacing Mg(2+) in magnesium lithospermate B (Mg-LSB) isolated from danshen (Salvia miltiorrhiza) with other metal ions could affect its potency in inhibition of Na(+)/K(+)-ATPase activity. METHODS: Eight metal ions (Na(+), K(+), Mg(2+), Cr(3+), Mn(2+), Co(2+), Ni(2+), and Zn(2+)) were used to form complexes with LSB. The activity of Na(+)/K(+)-ATPase was determined by measuring the amount of inorganic phosphate (Pi) liberated from ATP. Human adrenergic neuroblastoma cell line SH-SY5Y was used to assess the intracellular Ca(2+) level fluctuation and cell viability. The metal binding site on LSB and the binding mode of the metal-LSB complexes were detected by NMR and visible spectroscopy, respectively. RESULTS: The potencies of LSB complexed with Cr(3+), Mn(2+), Co(2+), or Ni(2+) increased by approximately 5 times compared to the naturally occurring LSB and Mg-LSB. The IC50 values of Cr-LSB, Mn-LSB, Co-LSB, Ni-LSB, LSB, and Mg-LSB in inhibition of Na(+)/K(+)-ATPase activity were 23, 17, 26, 25, 101, and 128 µmol/L, respectively. After treatment of SH-SY5Y cells with the transition metal-LSB complexes (25 µmol/L), the intracellular Ca(2+) level was substantially elevated, and the cells were viable for one day. The transition metals, as exemplified by Co(2+), appeared to be coordinated by two carboxylate groups and one carbonyl group of LSB. Titration of LSB against Co(2+) demonstrated that the Co-LSB complex was formed with a Co(2+):LSB molar ratio of 1:2 or 1:1, when [Co(2+)] was less than half of the [LSB] or higher than the [LSB], respectively. CONCLUSION: LSB complexed with Cr(3+), Mn(2+), Co(2+), or Ni(2+) are stable, non-toxic and more potent in inhibition of Na(+)/K(+)-ATPase. The transition metal-LSB complexes have the potential to be superior substitutes for cardiac glycosides in the treatment of congestive heart failure.

HIVEP3 inhibits fate decision of CD8+ invariant NKT cells after positive selection.

CD8+ invariant natural killer T (iNKT) cells are functionally different from other iNKT cells and are enriched in human but not in mouse. To date, their developmental pathway and molecular basis for fate decision remain unclear. Here, we report enrichment of CD8+ iNKT cells in neonatal mice due to their more rapid maturation kinetics than CD8- iNKT cells. Along developmental trajectories, CD8+ and CD8- iNKT cells separate at stage 0, following stage 0 double-positive iNKT cells, and differ in HIVEP3 expression. HIVEP3 is lowly expressed in stage 0 CD8+ iNKT cells and negatively controls their development, whereas it is highly expressed in stage 0 CD8- iNKT cells and positively controls their development. Despite no effect on IFN-γ, HIVEP3 inhibits granzyme B but promotes interleukin-4 production in CD8+ iNKT cells. Together, we reveal that, as a negative regulator for CD8+ iNKT fate decision, low expression of HIVEP3 in stage 0 CD8+ iNKT cells favors their development and T helper 1-biased cytokine responses as well as high cytotoxicity.

Site specificity of OH α-H abstraction reaction for a ß-hairpin peptide: an ab initio study.

A ß-hairpin peptide (PDB ID 1UAO) was modeled to explore the backbone oxidation of a protein by an OH radical to abstract one α-H atom with ab initio calculation at the B3LYB/6-31G(d) without any constraint. Three glycine residues located at three different sites in 1UAO were used to examine the possible site specificity of this backbone oxidation. The pre- and post-reactive complexes along with their associated transition states were located and verified by the intrinsic reaction coordinate method. The reaction profile of these α-H abstraction reactions was constructed. The effects of the aqueous solution were estimated by the conductor-like polarizable continuum model (CPCM) model. Rate constants were calculated with transition state theory. The reaction rate of the OH α-H abstraction varies among these three different sites. The differences among these three sites were rationalized in terms of the molecular and electronic structures of the reactive complexes along the reaction pathway. The explicit solvation effect was estimated through the similar abstraction of a zwitterionic glycine with the combination of microsolvation and a CPCM model. Our results indicate that the α-H abstraction at certain sites requires explicit salvation to obtain accurate results. A replica exchange molecular dynamics simulation was performed to demonstrate the structural change due to this type of abstraction.

Antcin A, a steroid-like compound from Antrodia camphorata, exerts anti-inflammatory effect via mimicking glucocorticoids.

AIM: To determine the active ingredient of Niuchangchih (Antrodia camphorata) responsible for its anti-inflammatory effects and the relevant molecular mechanisms. METHODS: Five major antcins (A, B, C, H, and K) were isolated from fruiting bodies of Niuchangchih. Structural similarity between the antcins and 2 glucocorticoids (cortisone and dexamethasone) was compared. After incubation with each compound, the cytosolic glucocorticoid receptor (GR) was examined for its migration into the nucleus. Mo lecular docking was performed to model the tertiary structure of GR associated with antcins. RESULTS: Incubation with cortisone, dexamethasone or antcin A (but not antcins B, C, H, and K) led to the migration of glucocorticoid receptor into the nucleus. The minimal concentration of antcin A, cortisone and dexamethasone to induce nuclear migration of glucocorticoid receptor was 10, 1, and 0.1 mol/L, respectively. The results are in agreement with the simulated binding affinity scores of these three ligands docking to the glucocorticoid receptor. Molecular modeling indicates that C-7 of antcin A or glucocorticoids is exposed to a hydrophobic region in the binding cavity of the glucocorticoid receptor, and the attachment of a hydrophilic group to C-7 of the other four antcins presumably results in their being expelled when docking to the cavity. CONCLUSION: The anti-inflammatory effect of Niuchangchih is, at least, partly attributed to antcin A that mimics glucocorticoids and triggers translocation of glucocorticoid receptor into nucleus to initiate the suppressing inflammation.