To resolve recent natural immune defense effects of antimicrobial peptides in the gastrointestinal tract

The human gut is the normal habitat of a lot of microorganisms; in the long process of evolution they have developed a symbiotic relationship with the host. Under normal circumstances they do not damage the health, which totally owes to the barrier functions of the integral intestinal mucosa. Intestinal lnucosal barriers are mainly composed of four parts： mechanical barrier, immune barrier, chemical and biological barrier. Each of these functions has corresponding structural basis, an important barrier to prevent harmful substances and pathogens in the gut into the inner environment of the body, and to maintain a stable internal environment.

Cloning of Immune System-related Gene ApTOLL1 and Its Expression in Nosema-infected Antheraea pernyi

[ Objective ] This study aimed to identify the immune system-related TOLL-like receptor family gene of Aherea pernyi, to lay the foundation for further investigating the immune mechanism of Antherea perny/. [ Method] Immune system-related TOLL-like receptor family gene of Antherea perny/was cloned for se- quencing and phylogenetic analysis ; in addition, expression variations of TOLL-like receptor family gene in Antherea pernyi infected with Nosema pernyi and Nosema bombycis were detected to analyze the differences in immunological reactivity of Antherea pernyi to Nosema infection. [ Result] Based on cDNA cloning and sequen- cing, an immune system-related gene fragment was isolated from Antherea pernyi, which is the most homologous to the ToUl gene in Toll signaling pathway of Bom- byx mot/according to the sequencing result and phylogenetic analysis, which is named ApTolll gene. Subsequently, Antherea pernyi pupae were injected respective- ly with Nosema bombycis and Nosema pernyi, fluorescent real-time quantitative PCR analysis showed that ApTolll was abundantly expressed in Antherea pernyi pupa 2 h after Nosema bombycis injection, which began to express in Antherea pernyi pupa 11 h after Nosema pernyi injection, indicating that the immune response time induced by various Nosema strains varies in Toll signaling pathway of Antherea perny/. [ Conclusion ] ApTolll gene of Antherea perny/was first cloned in this study, which provides reference for further investigating the immune mechanism of Antherea pernyi.

The life-history trait trade-offs mediated by reproduction and immunity in the brown planthopper,Nilaparvata lugens Stål

Reproduction and immune defense are costly functions,and they are expected to tradeoff with each other to drive evolution.The brown planthopper(BPH),Nilaparvata lugens Stål(Hemiptera,Delphacidae),is a global superpest that mostly damages rice crops.Yeast-like symbionts(YLS)exist in the abdominal fat body tissue and are tightly associated with the development,growth,and reproduction of BPH.Our previous research demonstrated that mating behavior promotes the release of YLS from the fat body into the hemolymph in the BPH,thereby triggering an immune response.Additionally,the fitness costs related to life-history traits of BPH(such as survival rate)have a strong dependence on the relative abundance of YLS.However,the possible relationship between reproduction and the immune response in BPH has not been identified.In this study,an omics-based approach was used to analyze the transcriptome of fat body tissues in mated and unmated BPH at 72 h post-eclosion,from which two antimicrobial peptide genes,NlDefensin A(NlDfA)and NlDefensin B(NlDfB),were selected since they were highly expressed in mated BPH.Subsequently,the full-length cDNA sequences of the NlDfA and NlDfB genes were cloned and analyzed.qPCR results showed up-regulation of the NlDfA and NlDfB genes in mated BPH when compared to unmated BPH.Spatial-temporal expression analysis indicated that the NlDfA and NlDfB genes were expressed in all tissues and developmental stages,and they were most highly expressed in the fat body at 24 h post-eclosion.Moreover,the symbionts in BPH were significantly inhibited by the in vitro expression of the NlDfA and NlDfB proteins.Furthermore,RNA interference(RNAi)-mediated suppression of NlDfA and NlDfB dramatically increased the relative abundance of YLS in the fat body,while YLS in the hemolymph decreased significantly.These BPHs also displayed some fitness disadvantages in survival,fecundity,hatchability,and possibly the vertical transmission of YLS from hemolymph to egg.Our results indicated that mating could heighten the immunity of BPH by upregulating the expression of the NlDfA and NlDfB genes,which protect the host from pathogen challenges during reproduction.However,the reduced content of YLS may act as a fitness disadvantage in dictating the life-history traits of BPH.This work has significant theoretical and practical implications for the precise green control technology that involves crucial gene targeting,as well as for the“endosymbionts for pest control”strategy in insects.

CD47 decline in pancreatic islet cells promotes macrophage-mediated phagocytosis in type Ⅰ diabetes

BACKGROUND Type Ⅰ diabetes(T1D)is characterized by insulin loss caused by inflammatory cells that excessively infiltrate and destroy the pancreas,resulting in dysregulation of tissue homeostasis,mechanobiological properties,and the immune response.The streptozotocin(STZ)-induced mouse model exhibits multiple features of human T1D and enables mechanistic analysis of disease progression.However,the relationship between the mechanochemical signaling regulation of STZ-induced T1D and macrophage migration and phagocytosis is unclear.AIM To study the mechanochemical regulation of STZ-induced macrophage response on pancreatic beta islet cells to gain a clearer understanding of T1D.METHODS We performed experiments using different methods.We stimulated isolated pancreatic beta islet cells with STZ and then tested the macrophage migration and phagocytosis.RESULTS In this study,we discovered that the integrin-associated surface factor CD47 played a critical role in immune defense in the STZ-induced T1D model by preventing pancreatic beta islet inflammation.In comparison with healthy mice,STZ-treated mice showed decreased levels of CD47 on islet cells and reduced interaction of CD47 with signal regulatory proteinα(SIRPα),which negatively regulates macrophage-mediated phagocytosis.This resulted in weakened islet cell immune defense and promoted macrophage migration and phagocytosis of target inflammatory cells.Moreover,lipopolysaccharide-activated human acute monocytic leukemia THP-1 cells also exhibited enhanced phagocytosis in the STZ-treated islets,and the aggressive attack of the inflammatory islets correlated with impaired CD47-SIRPαinteractions.In addition,CD47 overexpression rescued the pre-labeled targeted cells.CONCLUSION This study indicates that CD47 deficiency promotes the migration and phagocytosis of macrophages and provides mechanistic insights into T1D by associating the interactions between membrane structures and inflammatory disease progression.

Pufferfish gasdermin Ea is a significant player in the defense against bacterial pathogens

Gasdermins(GSDMs)are proteins cleaved by caspase(CASP)to trigger pyroptosis.In teleosts,pyroptosis is mediated by gasdermin E(GSDME).The Pufferfish,Takifugu rubripes,possesses two GSDME orthologs:named TrGSDMEa and TrGSDMEb.TrGSDMEa is cleaved by CASP3/7 to liberate the N-terminal(NT)domain that can trigger pyroptosis in mammalian cells.However,the biological function of TrGSDMEa in pufferfish is unknown,and TrGSDMEb is poorly studied.We found that TrGSDMEb was cleaved by CASP1/3/6/7/8,but the resulting NT domain,despite its similarity to TrGSDMEa-NT domain in sequence and structure,failed to induce pyroptosis.TrGSDMEa and TrGSDMEb exhibited similar expression patterns in pufferfish under normal physiological conditions but were up-and downregulated,respectively,in expression during Vibrio harveyi and Edwardsiella tarda infection.Bacterial infection induced the activation of TrGSDMEa and CASP3/7 in pufferfish cells,resulting in pyroptosis accompanied with IL-1βproduction and maturation.Inhibition of TrGSDMEa-mediated pyroptosis via TrCASP3/7 reduced the death of pufferfish cells and augmented bacterial dissemination in fish tissues.Structure-oriented mutagenesis identified 16 conserved residues in teleost GSDMEa that were required for the pore formation or auto-inhibition of GSDMEa.This study illustrates the role of GSDMEa-mediated pyroptosis in teleost defense against bacterial pathogens and provides new insights into the structure-based function of vertebrate GSDME.

Innate immunity in tuberculosis: host defense vs pathogen evasion

The major innate immune cell types involved in tuberculosis(TB)infection are macrophages,dendritic cells(DCs),neutrophils and natural killer(NK)cells.These immune cells recognize the TB-causing pathogen Mycobacterium tuberculosis(Mtb)through various pattern recognition receptors(PRRs),including but not limited to Toll-like receptors(TLRs),Nod-like receptors(NLRs)and C-type lectin receptors(CLRs).Upon infection by Mtb,the host orchestrates multiple signaling cascades via the PRRs to launch a variety of innate immune defense functions such as phagocytosis,autophagy,apoptosis and inflammasome activation.In contrast,Mtb utilizes numerous exquisite strategies to evade or circumvent host innate immunity.Here we discuss recent research on major host innate immune cells,PRR signaling,and the cellular functions involved in Mtb infection,with a specific focus on the host’s innate immune defense and Mtb immune evasion.A better understanding of the molecular mechanisms underlying host–pathogen interactions could provide a rational basis for the development of effective anti-TB therapeutics.

The function of small RNAs in plant biotic stress response

Small RNAs（s RNAs） play essential roles in plants upon biotic stress. Plants utilize RNA silencing machinery to facilitate pathogen-associated molecular pattern-triggered immunity and effector-triggered immunity to defend against pathogen attack or to facilitate defense against insect herbivores. Pathogens, on the other hand, are also able to generate effectors and s RNAs to counter the host immune response. The arms race between plants and pathogens/insect herbivores has triggered the evolution of s RNAs,RNA silencing machinery and pathogen effectors. A great number of studies have been performed to investigate the roles of s RNAs in plant defense, bringing in the opportunity to utilize s RNAs in plant protection. Transgenic plants with pathogen-derived resistance ability or transgenerational defense have been generated, which show promising potential as solutions for pathogen/insect herbivore problems in the field. Here we summarize the recent progress on the function of s RNAs in response to biotic stress, mainly in plant-pathogen/insect herbivore interaction,and the application of s RNAs in disease and insect herbivore control.