Pseudomonas Cyclic Lipopeptide Medpeptin:Biosynthesis and Modulation of Plant Immunity

The multifunctional secondary metabolites known as cyclic lipopeptides(CLPs),which are produced by a large variety of bacteria,have become a key category of plant immunity elicitors.Pseudomonas-CLPs(PsCLPs)are extremely diverse in structure and biological activity.However,an understanding of CLP-plant structure–function interactions currently remains elusive.Here,we identify medpeptin,a novel CLP from Pseudomonas mediterranea that consists of 22 amino acids.Medpeptin is synthesized by a non-ribosomal peptide synthase(NRPS)gene cluster and regulated by a quorum-sensing system.Further research indicates that medpeptin does not exhibit antimicrobial activity;instead,it induces plant cell death immunity and confers resistance to bacterial infection.Comparative transcriptome analysis and virus-induced gene silencing(VIGS)reveal a set of immune signaling candidates involved in medpeptin perception.Silencing of a cell-wall leucine-rich repeat extensin protein(NbLRX3)or a receptor-like protein kinase(NbRLK25)—but not BAK1 or SGT1—compromises medpeptin-triggered cell death and resistance to pathogen infection in Nicotiana benthamiana.Our findings point to a noncanonical mechanism of CLP sensing and suggest perspectives for the development of plant disease resistance.

Safety and efficacy of meplazumab in healthy volunteers and COVID-19 patients: a randomized phase 1 and an exploratory phase 2 trial

Recent evidence suggests that CD147 serves as a novel receptor for severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)infection.Blocking CD147 via anti-CD147 antibody could suppress the in vitro SARS-CoV-2 replication.Meplazumab is a humanized anti-CD147 IgG_(2) monoclonal antibody,which may effectively prevent SARS-CoV-2 infection in coronavirus disease 2019(COVID-19)patients.Here,we conducted a randomized,double-blinded,placebo-controlled phase 1 trial to evaluate the safety,tolerability,and pharmacokinetics of meplazumab in healthy subjects,and an open-labeled,concurrent controlled add-on exploratory phase 2 study to determine the efficacy in COVID-19 patients.In phase 1 study,59 subjects were enrolled and assigned to eight cohorts,and no serious treatment-emergent adverse event(TEAE)or TEAE grade≥3 was observed.The serum and peripheral blood Cmax and area under the curve showed non-linear pharmacokinetic characteristics.No obvious relation between the incidence or titer of positive anti-drug antibody and dosage was observed in each cohort.The biodistribution study indicated that meplazumab reached lung tissue and maintained>14 days stable with the lung tissue/cardiac blood-pool ratio ranging from 0.41 to 0.32.In the exploratory phase 2 study,17 COVID-19 patients were enrolled,and 11 hospitalized patients were involved as concurrent control.The meplazumab treatment significantly improved the discharged(P=0.005)and case severity(P=0.021),and reduced the time to virus negative(P=0.045)in comparison to the control group.These results show a sound safety and tolerance of meplazumab in healthy volunteers and suggest that meplazumab could accelerate the recovery of patients from COVID-19 pneumonia with a favorable safety profile.

Thermal and Redox Dual Responsive Poly(L-glutamate)with Oligo(ethylene glycol)Side-chains

A series of poly（L-glutamate）s grafted with oligo（ethylene glycol） （OEG） side-chains through the thioether linkages （PALGn-g-EGx, x = 2, 3 and 4） were prepared by ring-opening polymerization （ROP） of γ-allyl-L-glutamate N-carboxyanhydride （ALG-NCA） and thiol-ene photoaddition. The chemical structures and physical properties were characterized by 1H-NMR, Fourier transform infrared （FTIR）, circular dichroism （CD）, etc. The PALGn-g-EGx samples with x = 3 and 4 displayed lower critical solution temperature （LCST） in water due to the presence of OEG units. The clouding point （CP） of polypeptides can be finely tuned by changing the side chain structures, molecular weights and sample concentrations. In addition, the thioether linkages in the side chains offer additional redox-responsive properties. The influence of both OEG units and thioether linkages on the LCST behavior was systematically investigated. This work provides an efficient way to prepare multi-stimuli responsive materials with highly tunable properties.

Clinical and Molecular Characteristics in 100 Chinese Pediatric Patients with m.3243A〉G Mutation in Mitochondrial DNA

Background： Mitochondrial diseases are a group of energy metabolic disorders with multisystem involvements. Variable clinical features present a major challenge in pediatric diagnoses. We summarized the clinical spectrum of m.3243A〉G mutation in Chinese pediatric patients, to define the common clinical manifestations and study the correlation between heteroplasmic degree of the mutation and clinical severity of the disease. Methods： Clinical data of one-hundred pediatric patients with symptomatic mitochondrial disease harboring m.3243A〉G mutation from 2007 to 2013 were retrospectively reviewed. Detection of m.3243A〉G mutation ratio was performed by polymerase chain reaction （PCR）-restriction fragment length polymorphism. Correlation between m.3243A〉G mutation ratio and age was evaluated. The differences in clinical symptom frequency of patients with low, middle, and high levels of mutation ratio were analyzed by Chi-square test. Results： Sixty-six patients （66%） had suffered a delayed diagnosis for an average of 2 years. The most frequent symptoms were seizures （76%）, short stature （73%）, elevated plasma lactate （70%）, abnormal magnetic resonance imaging/computed tomography （MRI/CT） changes （68%）, vomiting （55%）, decreased vision （52%）, headache （50%）, and muscle weakness （48%）. The mutation ratio was correlated negatively with onset age （r = -0.470, P 〈 0.001）. Myopathy was more frequent in patients with a high level of mutation ratio. However, patients with a low or middle level of m.3243A〉G mutation ratio were more likely to suffer hearing loss, decreased vision, and gastrointestinal disturbance than patients with a high level of mutation ratio. Conclusions： Our study showed that half of Chinese pediatric patients with m.3243A〉G mutation presented seizures, short stature, abnormal MRI/CT changes, elevated plasma lactate, vomiting, and headache. Pediatric patients with these recurrent symptoms should be considered for screening m.3243A〉G mutation. Clinical manifestations and laboratory abnormalities should be carefully monitored in patients with this point mutation.

Reference Intervals of Mitochondrial DNA Copy Number in Peripheral Blood for Chinese Minors and Adults

Background： Mitocbondrial DNA （mtDNA） content measured by different techniques cannot be compared between studies, and age- and tissue-related control values are hardly available. In the present study, we aimed to establish the nonllal reference range of mtDNA copy number in the Chinese population. Methods： Two healthy cohorts of 200 Chinese minors （0.1 18.0 years） and 200 adults （18.0-88.0 years） were recruited. Then, they were further categorized into eight age groups. The absolute mtDNA copy number per cell was measured by a quantitative real-time polymerase chain reaction. We subsequently used this range to evaluate mtDNA content in tbur patients （0.5-4.0 years） with molecularly proven mitochondrial depletion syndromes （MDSs） and 83 cases of mitochondrial disease patients harboring the m.3243A〉G mutation. Results： The reference range ofmtDNA copy number in peripheral blood was 175-602 copies/cell （mean： 325 copies/cell） in minors and 164 500 copies/cell （mean： 287 copies/cell） in adults. There was a decreasing trend in mtDNA copy number in blood with increasing age, especially in 0-2-year-old and 〉50-year-old donors. The mean mtDNA copy number level among the mitochondrial disease patients with m.3243A〉G mutation was significantly higher than that ofhealtby controls. The intDNA content ofPOLG, DGUOK, TK2, and SUCLA2 genes in blood samples from MDS patients was reduced to 25%, 38%, 32%, and 24%, respectively. Conclusions： We primarily establish the refeerence intervals of mtDNA copy number, which might contribute to the clinical diagnosis and monitoring of mitochondrial disease.

Molecular diagnosis of phenylketonuria in 157 Chinese families and the results of prenatal diagnosis in these families

To the Editor:Phenylketonuria(PKU)is an autosomal recessive genetic disease caused by pathogenic variants in the phenylalanine hydroxylase(PAH)gene encoding phenylalanine hydroxylase,a key enzyme in the metabo-lism of phenylalanine.Early low-phenylalanine diet improves most of the neuropsychological disorders,but it is difficult to be maintained for a long period of time.

Next-generation sequencing verified by multiplex ligation-dependent probe amplification to detect a new copy number variations in a child with heterozygous familial hypercholesterolemia

Familial hypercholesterolemia(FH)is a common autosomal dominant disorder of lipid metabolism.Mutations in the low density lipoprotein receptor gene(LDLR)represent the majority of FH cases.LDLR mutations are codominantly inherited.Commonly,the clinical phenotype associated with heterozygous mutations is relatively mild,whereas homozygous mutations,compound heterozygous mutations,and double gene mutations in LDLR lead to severe phenotypes.However,some heterozygous FH(HeFH)and homozygous FH(HoFH)patients have similar lipid levels.Because of the quite different prognosis and treatments for these patients,accurate diagnosis is especially important.Gene testing plays an essential role in the diagnosis of FH,but finding the appropriate mutations by genetic testing is not always simple.