A non-peptide-based chymotrypsin-targeted long-wavelength emission fluorescent probe with large Stokes shift and its application in bioimaging

As a hydrolase,chymotrypsin(CHT)is involved in many physiological activities,and its abnormal activity is closely related to diabetes,pancreatic fibrosis,chronic pancreatitis and pancreatic cancer.In this work,an innovative long-wavelength emission fluorescent probe TCF-CHT was designed and synthesized for the high specificity detection of CHT,which utilized TCF-OH and a mimetic peptide substrate 4-bromobutyryl as chromogenic group and recognition group,respectively.TCF-CHT exhibited excellent selectivity and eye-catching sensitivity(8.91 ng/m L)towards CHT,“off-on”long-wavelength emission at 670 nm and large Stokes shift(140 nm).Furthermore,the successful fulfillment and perfect performance in imaging endogenous CHT in complex organisms(P815 cells,HepG2 cells,zebrafish and tumor-bearing mice)verified its potential as a powerful tool for the recognition of CHT in complicated biological environments.

Human monoclonal antibodies block the binding of SARS-CoV-2 spike protein to angiotensin converting enzyme 2 receptor

According to the World Health Organization(WHO)newly updated situation report on March 18th,2020,the coronavirus disease 2019(COVID-19)pandemic has confirmed 191,127 cases and claimed 7807 deaths worldwide.1 The etiological agent of COVID-19 has been identified as a novel coronavirus,the severe acute respiratory syndrome coronavirus 2(SARS-CoV-2),belonging to Sarbecovirus subgenus(genus Betacoronavirus,family Coronaviridae)and showing 79.6 and 96.2%sequence identity in nucleotide to SARS-CoV and a bat coronavirus(BatCoV RaTG13),respectively.2–4 Like SARS-CoV infection,a substantial fraction of COVID-19 patients exhibits severe respiratory symptoms and has to be hospitalized in intensive care unit.5–8 Although the mortality rate of COVID-19 is significantly lower than that of SARS-CoV infection,SARS-CoV-2 shows much higher human-to-human transmission rate,rapidly leading to a global pandemic declared by WHO on March 11th,2020.

Conversion of effector CD4^(+)T cells to a CD8^(+)MHC Ⅱ-recognizing lineage

CD4^(+)and CD8^(+)T cells are dichotomous lineages in adaptive immunity.While conventionally viewed as distinct fates that are fixed after thymic development,accumulating evidence indicates that these two populations can exhibit significant lineage plasticity,particularly upon TCR-mediated activation.We define a novel CD4^(-)CD8αβ^(+)MHC Ⅱ-recognizing population generated by lineage conversion from effector CD4^(+)T cells.CD4-CD8αβ^(+)effector T cells downregulated the expression of T helper cell-associated costimulatory molecules and inaeased the expression of cytotoxic T lymphocyte-associated cytotoxic molecules.This shift in functional potential corresponded with a CD8^(+)-lineage skewed transcriptional profile.TCRβ repertoire sequencing and in vivo genetic lineage tracing in acutely infected wild-type mice demonstrated that CD4^(-)CD8αβ^(+)effector T cells arise from fundamental lineage reprogramming of bona fide effector CD4^(+)T cells.Impairing autophagy via functional deletion of the initiating kinase Vps34 or the downstream enzyme Atg7 enhanced the generation of this cell population.These findings suggest that effector CD4^(+)T cells can exhibit a previously unreported degree of skewing towards the CD8^(+)T cell lineage,which may point towards a novel direction for HIV vaccine design.

Tropoelastin improves adhesion and migration of intra-articular injected infrapatellar fat pad MSCs and reduces osteoarthritis progression

Intra-articular injection of mesenchymal stem cells(MSCs)is a promising strategy for osteoarthritis(OA)treatment.However,more and more studies reveal that the injected MSCs have poor adhesion,migration,and survival in the joint cavity.A recent study shows that tropoelastin(TE)regulates adhesion,proliferation and phenotypic maintenance of MSCs as a soluble additive,indicating that TE could promote MSCs-homing in regenerative medicine.In this study,we used TE as injection medium,and compared it with classic media in MSCs intra-articular injection such as normal saline(NS),hyaluronic acid(HA),and platelet-rich plasma(PRP).We found that TE could effectively improve adhesion,migration,chondrogenic differentiation of infrapatellar fat pad MSCs(IPFP-MSCs)and enhance matrix synthesis of osteoarthritic chondrocytes(OACs)in indirect-coculture system.Moreover,TE could significantly enhance IPFP-MSCs adhesion via activation of integrin β1,ERK1/2 and vinculin(VCL)in vitro.In addition,intra-articular injection of TE-IPFP MSCs suspension resulted in a short-term increase in survival rate of IPFP-MSCs and better histology scores of rat joint tissues.Inhibition of integrin β1 or ERK1/2 attenuated the protective effect of TE-IPFP MSCs suspension in vivo.In conclusion,TE promotes performance of IPFP-MSCs and protects knee cartilage from damage in OA through enhancement of cell adhesion and activation of integrin β1/ERK/VCL pathway.Our findings may provide new insights in MSCs intra-articular injection for OA treatment.

Disease severity dictates SARS-CoV-2-specific neutralizing antibody responses in COVID-19

COVID-19 patients exhibit differential disease severity after SARS-CoV-2 infection.It is currently unknown as to the correlation between the magnitude of neutralizing antibody(NAb)responses and the disease severity in COVID-19 patients.In a cohort of 59 recovered patients with disease severity including severe,moderate,mild,and asymptomatic,we observed the positive correlation between serum neutralizing capacity and disease severity,in particular,the highest NAb capacity in sera from the patients with severe disease,while a lack of ability of asymptomatic patients to mount competent NAbs.Furthermore,the compositions of NAb subtypes were also different between recovered patients with severe symptoms and with mild-tomoderate symptoms.These results reveal the tremendous heterogeneity of SARS-CoV-2-specific NAb responses and their correlations to disease severity,highlighting the needs of future vaccination in COVID-19 patients recovered from asymptomatic or mild illness.

The role of microRNAs in B-cell development and function

MicroRNA （miRNA）-mediated gene silencing at the translational level has led to novel discoveries for numerous biological processes. Recently, there has been increasing evidence to indicate that miRNAs are involved in normal immune functions and inflammation. In this review, we focus on recent advances that have elucidated the role of miRNAs in B-cell development, differentiation, apoptosis and function. While the regulatory mechanisms of miRNAs in controlling and maintaining B-cell fate remain largely uncharacterized, further studies on miRNAs and their targets will increase our understanding of B-cell development and function. Such studies may be able to provide new therapeutic strategies for treating autoimmune diseases.

The kinase p38αfunctions in dendritic cells to regulate Th2-cell differentiation and allergic inflammation

Dendritic cells(DCs)play a critical role in controlling T helper 2(Th2)cell-dependent diseases,but the signaling mechanism that triggers this function is not fully understood.We showed that p38αactivity in DCs was decreased upon HDM stimulation and dynamically regulated by both extrinsic signals and Th2-instructive cytokines.p38α-specific deletion in cDC1s but not in cDC2s or macrophages promoted Th2 responses under HDM stimulation.Further study showed that p38αin cDC1s regulated Th2-cell differentiation by modulating the MK2−c-FOS−IL-12 axis.Importantly,crosstalk between p38α-dependent DCs and Th2 cells occurred during the sensitization phase,not the effector phase,and was conserved between mice and humans.Our results identify p38αsignaling as a central pathway in DCs that integrates allergic and parasitic instructive signals with Th2-instructive cytokines from the microenvironment to regulate Th2-cell differentiation and function,and this finding may offer a novel strategy for the treatment of allergic diseases and parasitic infection.

A potent human monoclonal antibody with pan-neutralizing activities directly dislocates S trimer of SARS-CoV-2 through binding both up and down forms of RBD

The severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)has caused a global pandemic of novel coronavirus disease(COVID-19).The neutralizing monoclonal antibodies(mAbs)targeting the receptor-binding domain(RBD)of SARS-CoV-2 are among the most promising strategies to prevent and treat COVID-19.However,SARS-CoV-2 variants of concern(VOCs)profoundly reduced the efficacies of most of mAbs and vaccines approved for clinical use.Herein,we demonstrated mAb 35B5 efficiently neutralizes both wild-type(WT)SARS-CoV-2 and VOCs.

Mapping Cell Phenomics with Multiparametric Flow Cytometry Assays

Phenomics explores the complex interactions among genes,epigenetics,symbiotic microorganisms,diet,and environmental exposure based on the physical,chemical,and biological characteristics of individuals and groups.Increasingly efficient and comprehensive phenotyping techniques have been integrated into modern phenomics-related research.Multicolor flow cytometry technology provides more measurement parameters than conventional flow cytometry.Based on detailed descriptions of cell phenotypes,rare cell populations and cell subsets can be distinguished,new cell phenotypes can be discovered,and cell apoptosis characteristics can be detected,which will expand the potential of cell phenomics research.Based on the enhancements in multicolor flow cytometry hardware,software,reagents,and method design,the present review summarizes the recent advances and applications of multicolor flow cytometry in cell phenomics,illuminating the potential of applying phenomics in future studies.