A unique NLRC4 receptor from echinoderms mediates Vibrio phagocytosis via rearrangement of the cytoskeleton and polymerization of F-actin

Many members of the nucleotide-binding and oligomerization domain (NACHT)- and leucine-rich-repeat-containing protein (NLR) family play crucial roles in pathogen recognition and innate immune response regulation. In our previous work, a unique and Vibrio splendidus-inducible NLRC4 receptor comprising Ig and NACHT domains was identified from the sea cucumber Apostichopus japonicus, and this receptor lacked the CARD and LRR domains that are typical of common cytoplasmic NLRs. To better understand the functional role of AjNLRC4, we confirmed that AjNLRC4 was a bona fide membrane PRR with two transmembrane structures. AjNLRC4 was able to directly bind microbes and polysaccharides via its extracellular Ig domain and agglutinate a variety of microbes in a Ca2+-dependent manner. Knockdown of AjNLRC4 by RNA interference and blockade of AjNLRC4 by antibodies in coelomocytes both could significantly inhibit the phagocytic activity and elimination of V. splendidus. Conversely, overexpression of AjNLRC4 enhanced the phagocytic activity of V. splendidus, and this effect could be specifically blocked by treatment with the actin-mediated endocytosis inhibitor cytochalasin D but not other endocytosis inhibitors. Moreover, AjNLRC4-mediated phagocytic activity was dependent on the interaction between the intracellular domain of AjNLRC4 and the β-actin protein and further regulated the Arp2/3 complex to mediate the rearrangement of the cytoskeleton and the polymerization of F-actin. V. splendidus was found to be colocalized with lysosomes in coelomocytes, and the bacterial quantities were increased after injection of chloroquine, a lysosome inhibitor. Collectively, these results suggested that AjNLRC4 served as a novel membrane PRR in mediating coelomocyte phagocytosis and further clearing intracellular Vibrio through the AjNLRC4-β-actin-Arp2/3 complex-lysosome pathway.

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Decoding the role of CBLB for innate immune responses regulating systemic dissemination during Non-Tuberculous Mycobacteria infection

10.1101/2020.05.28.117663 ◽

2020 ◽

Author(s):

Srinivasu Mudalagiriyappa ◽

Jaishree Sharma ◽

Hazem F. M. Abdelaal ◽

Thomas C. Kelly ◽

Woosuk Choi ◽

...

Keyword(s):

T Cell ◽

Immune Responses ◽

Granulomatous Inflammation ◽

Innate Immune ◽

Dependent Manner ◽

Innate Immune Responses ◽

Inflammatory Monocytes ◽

Cell Immunity

AbstractNon-Tuberculous Mycobacteria (NTM) are ubiquitous in nature, present in soil and water, and cause primary leading to disseminated infections in immunocompromised individuals. NTM infections are surging in recent years due to an increase in an immune-suppressed population, medical interventions, and patients with underlying lung diseases. Host regulators of innate immune responses, frontiers for controlling infections and dissemination, are poorly defined during NTM infections. Here, we describe the role of CBLB, an E3-ubiquitin ligase, for innate immune responses and disease progression in a mouse model of NTM infection under compromised T-cell immunity. We found that CBLB thwarted NTM growth and dissemination in a time- and infection route- dependent manner. Mechanistically, we uncovered defects in many innate immune cells in the absence of Cblb, including poor responses of NK cells, inflammatory monocytes, and conventional dendritic cells. Strikingly, Cblb-deficient macrophages were competent to control NTM growth in vitro. Histopathology suggested the lack of early formation of granulomatous inflammation in the absence of CBLB. Collectively, CBLB is essential to mount productive innate immune responses and help prevent the dissemination during an NTM infection under T-cell deficiency.

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Neutrophils in cardiovascular disease: warmongers, peacemakers, or both?

Cardiovascular Research ◽

10.1093/cvr/cvab302 ◽

2021 ◽

Author(s):

Gopalkrishna Sreejit ◽

Jillian Johnson ◽

Robert M Jaggers ◽

Albert Dahdah ◽

Andrew J Murphy ◽

...

Keyword(s):

Cardiovascular Disease ◽

Innate Immune ◽

Sterile Inflammation ◽

Immune Memory ◽

Dependent Manner ◽

Cell Type ◽

Complex Behaviour ◽

One Dimensional ◽

A Cell

Abstract Neutrophils, the most abundant of all leucocytes and the first cells to arrive at the sites of sterile inflammation/injury act as a double-edged sword. On one hand, they inflict a significant collateral damage to the tissues and on the other hand, they help facilitate wound healing by a number of mechanisms. Recent studies have drastically changed the perception of neutrophils from being simple one-dimensional cells with an unrestrained mode of action to a cell type that display maturity and complex behaviour. It is now recognized that neutrophils are transcriptionally active and respond to plethora of signals by deploying a wide variety of cargo to influence the activity of other cells in the vicinity. Neutrophils can regulate macrophage behaviour, display innate immune memory, and play a major role in the resolution of inflammation in a context-dependent manner. In this review, we provide an update on the factors that regulate neutrophil production and the emerging dichotomous role of neutrophils in the context of cardiovascular diseases, particularly in atherosclerosis and the ensuing complications, myocardial infarction, and heart failure. Deciphering the complex behaviour of neutrophils during inflammation and resolution may provide novel insights and in turn facilitate the development of potential therapeutic strategies to manage cardiovascular disease.

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Activation of nucleotide oligomerization domain containing protein 1 induces lipolysis through NF-κB and the lipolytic PKA activation in 3T3-L1 adipocytes

Biochemistry and Cell Biology ◽

10.1139/bcb-2013-0049 ◽

2013 ◽

Vol 91 (6) ◽

pp. 428-434 ◽

Cited By ~ 6

Author(s):

Jaanki S. Purohit ◽

Pan Hu ◽

Guoxun Chen ◽

Jay Whelan ◽

Naima Moustaid-Moussa ◽

...

Keyword(s):

Hormone Sensitive Lipase ◽

Dependent Manner ◽

Camp Production ◽

Nucleotide Oligomerization ◽

Hormone Sensitive ◽

Sirna Knockdown ◽

Dose Dependent ◽

Nucleotide Oligomerization Domain ◽

Oligomerization Domain

Obesity is associated with chronic inflammation. Toll-like receptors (TLR) and NOD-like receptors (NLR) are two families of pattern recognition receptors that play important roles in the immune response and inflammation in adipocytes. Activation of TLR4 has been shown to stimulate lipolysis from adipose tissue or adipocytes. However, effects of activation of nucleotide-oligomerization domain containing protein 1 (NOD1), one of the prominent members of NLRs, on adipocyte lipolysis have not been studied. Here we report that NOD1 activation by the synthetic ligands (Tri-DAP and C12-iEDAP) stimulated lipolysis in 3T3-L1 adipocytes in a time- and dose-dependent manner. C12-iEDAP-induced lipolysis was attenuated with NOD1 siRNA knockdown, demonstrating the specificity of the effects. Moreover, inhibition of the protein kinase A (PKA)/hormone sensitive lipase (HSL) and NF-κB pathways by the pharmacological inhibitors attenuated the lipolytic effects of C12-iEDAP. Furthermore, we show NOD1 activation induced PKA activation independent of cAMP production and inhibition of NF-κB pathways attenuated phosphorylation of selected PKA lipolytic targets (phosphorylation of Perilipin Ser 517 and HSL Ser 563). Taken together, our results demonstrate a novel role of NOD1 activation, via NF-κB/PKA lipolytic activation, in inducing lipolysis in adipocytes and suggest that NOD1 activation may contribute to dyslipidemia in obesity.

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MicroRNA-106a Inhibits Autophagy Process and Antimicrobial Responses by Targeting ULK1, ATG7, and ATG16L1 During Mycobacterial Infection

Frontiers in Immunology ◽

10.3389/fimmu.2020.610021 ◽

2021 ◽

Vol 11 ◽

Author(s):

Kunmei Liu ◽

Dantong Hong ◽

Fan Zhang ◽

Xin Li ◽

Meng He ◽

...

Keyword(s):

Immune Response ◽

Electron Microscope ◽

Mycobacterial Infection ◽

Inhibitory Effect ◽

Innate Immune ◽

Negative Regulator ◽

Dependent Manner ◽

Transmission Electron ◽

Dose Dependent

Autophagy is a key element of innate immune response against invading pathogens including Mycobacterium tuberculosis (M. tuberculosis). The emerging roles of microRNAs in regulating host antimicrobial responses against M. tuberculosis have gained widespread attention. However, the process by which miRNAs specifically influence antibacterial autophagy during mycobacterial infection is largely uncharacterized. In this study, we demonstrate a novel role of miR-106a in regulating macrophage autophagy against M. tuberculosis. H37Ra infection leads to downregulation of miR-106a in a time- and dose-dependent manner and concomitant upregulation of its three targets (ULK1, ATG7, and ATG16L1) in THP-1 macrophages. MiR-106a could inhibit autophagy activation and antimicrobial responses to M. tuberculosis by targeting ULK1, ATG7, and ATG16L1. Overexpression of miR-106a dramatically inhibited H37Ra-induced activation of autophagy in human THP-1 macrophages, whereas inhibitors of miR-106a remarkably promoted H37Ra-induced autophagy. The inhibitory effect of miR-106a on autophagy process during mycobacterial infection was also confirmed by Transmission Electron Microscope (TEM) observation. More importantly, forced expression of miR-106a increased mycobacterial survival, while transfection with miR-106a inhibitors attenuated the survival of intracellular mycobacteria. Taken together, these data demonstrated that miR-106a functioned as a negative regulator in autophagy and antimicrobial effects by targeting ULK1, ATG7, and ATG16L1 during M. tuberculosis infection, which may provide a potential target for developing diagnostic reagents or antibacterials against tuberculosis.

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The Role of Lipopeptidophosphoglycan in the Immune Response toEntamoeba histolytica

Journal of Biomedicine and Biotechnology ◽

10.1155/2010/254521 ◽

2010 ◽

Vol 2010 ◽

pp. 1-12 ◽

Cited By ~ 17

Author(s):

Isabel Wong-Baeza ◽

Marcela Alcántara-Hernández ◽

Ismael Mancilla-Herrera ◽

Itzmel Ramírez-Saldívar ◽

Lourdes Arriaga-Pizano ◽

...

Keyword(s):

Dendritic Cells ◽

Adaptive Immune System ◽

Innate Immune ◽

Amebic Liver Abscess ◽

Disease Development ◽

Dependent Manner ◽

Surface Molecule ◽

Adaptive Immune ◽

Molecular Patterns

The sensing of Pathogen Associated Molecular Patterns (PAMPs) by innate immune receptors, such as Toll-like receptors (TLRs), is the first step in the inflammatory response to pathogens.Entamoeba histolytica, the etiological agent of amebiasis, has a surface molecule with the characteristics of a PAMP. This molecule, which was termed lipopeptidophosphoglycan (LPPG), is recognized through TLR2 and TLR4 and leads to the release of cytokines from human monocytes, macrophages, and dendritic cells; LPPG-activated dendritic cells have increased expression of costimulatory molecules. LPPG activates NKT cells in a CD1d-dependent manner, and this interaction limits amebic liver abscess development. LPPG also induces antibody production, and anti-LPPG antibodies prevent disease development in animal models of amebiasis. Because LPPG is recognized by both the innate and the adaptive immune system (it is a “Pamptigen”), it may be a good candidate to develop a vaccine againstE. histolyticainfection and an effective adjuvant.

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Parasitic Infections: A Role for C-Type Lectins Receptors

BioMed Research International ◽

10.1155/2013/456352 ◽

2013 ◽

Vol 2013 ◽

pp. 1-11 ◽

Cited By ~ 25

Author(s):

Alicia Vázquez-Mendoza ◽

Julio César Carrero ◽

Miriam Rodriguez-Sosa

Keyword(s):

Dendritic Cells ◽

Immune Responses ◽

Innate Immune ◽

Parasitic Infections ◽

Dependent Manner ◽

Innate Immune Responses ◽

Parasite Infections ◽

Antigen Presenting ◽

Molecular Patterns

Antigen-presenting cells (APCs) sense the microenvironment through several types of receptors that recognize pathogen-associated molecular patterns. In particular, C-type lectins receptors (CLRs), which are expressed by distinct subsets of dendritic cells (DCs) and macrophages (MØs), recognize and internalize specific carbohydrate antigens in a Ca2+-dependent manner. The targeting of these receptors is becoming an efficient strategy for parasite recognition. However, relatively little is known about how CLRs are involved in both pathogen recognition and the internalization of parasites. The role of CLRs in parasite infections is an area of considerable interest because this research will impact our understanding of the initiation of innate immune responses, which influences the outcome of specific immune responses. This paper attempts to summarize our understanding of the effects of parasites’ interactions with CLRs.

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PilT and PilU are homohexameric ATPases that coordinate to retract type IVa pili

10.1101/634048 ◽

2019 ◽

Author(s):

Jennifer L. Chlebek ◽

Hannah Q. Hughes ◽

Aleksandra S. Ratkiewicz ◽

Rasman Rayyan ◽

Joseph Che-Yen Wang ◽

...

Keyword(s):

Bacterial Species ◽

Dependent Manner ◽

Acinetobacter Baylyi ◽

Bacterial Surface ◽

Type Iv ◽

Bona Fide ◽

Almost All

AbstractBacterial type IV pili are critical for diverse biological processes including horizontal gene transfer, surface sensing, biofilm formation, adherence, motility, and virulence. These dynamic appendages extend and retract from the cell surface. In many type IVa pilus systems, extension occurs through the action of an extension ATPase, often called PilB, while optimal retraction requires the action of a retraction ATPase, PilT. Many type IVa systems also encode a homolog of PilT called PilU. However, the function of this protein has remained unclear becausepilUmutants exhibit inconsistent phenotypes among type IV pilus systems and because it is relatively understudied compared to PilT. Here, we study the type IVa competence pilus ofVibrio choleraeas a model system to define the role of PilU. We show that the ATPase activity of PilU is critical for pilus retraction in PilT Walker A and/or Walker B mutants. PilU does not, however, contribute to pilus retraction in ΔpilTstrains. Thus, these data suggest that PilU is abona fideretraction ATPase that supports pilus retraction in a PilT-dependent manner. We also found that a ΔpilUmutant exhibited a reduction in the force of retraction suggesting that PilU is important for generating maximal retraction forces. Additionalin vitroandin vivodata show that PilT and PilU act as independent homo-hexamers that may form a complex to facilitate pilus retraction. Finally, we demonstrate that the role of PilU as a PilT-dependent retraction ATPase is conserved inAcinetobacter baylyi, suggesting that the role of PilU described here may be broadly applicable to other type IVa pilus systems.Author SummaryAlmost all bacterial species use thin surface appendages called pili to interact with their environments. These structures are critical for the virulence of many pathogens and represent one major way that bacteria share DNA with one another, which contributes to the spread of antibiotic resistance. To carry out their function, pili dynamically extend and retract from the bacterial surface. Here, we show that retraction of pili in some systems is determined by the combined activity of two motor ATPase proteins.

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An NAD+–dependent sirtuin depropionylase and deacetylase (Sir2La) from the probiotic bacterium Lactobacillus acidophilus NCFM

10.1101/252379 ◽

2018 ◽

Author(s):

Sita V. Olesen ◽

Nima Rajabi ◽

Birte Svensson ◽

Christian A. Olsen ◽

Andreas S. Madsen

Keyword(s):

Lactobacillus Acidophilus ◽

Probiotic Bacterium ◽

Dependent Manner ◽

Concentration Dependent Manner ◽

Steady State Kinetics ◽

Chain Acyl ◽

Bona Fide ◽

Lactobacillus Acidophilus Ncfm ◽

Hydrolysis Of

ABSTRACTSirtuins—a group of NAD+-dependent deacylases—have emerged as key in the connection between NAD+ metabolism and aging. This class of enzymes hydrolyze a range of ε-N-acyllysine PTMs and determining the repertoire of catalyzed deacylation reactions is of high importance to fully elucidate the roles of a given sirtuin. Here we have identified and produced two potential sirtuins from the probiotic bacterium Lactobacillus acidophilus NCFM and screening more than 80 different substrates, covering 26 acyl groups on five peptide scaffolds, showed that one of the investigated proteins—Sir2La—is a bona fide NAD+-dependent sirtuin, catalyzing hydrolysis of acetyl‐, propionyl‐, and butyryllysine. Further substantiating the identity as a sirtuin, known sirtuin inhibitors nicotinamide and suramin as well as a thioacetyllysine compound inhibit the deacylase activity in a concentration-dependent manner. Based on steady-state kinetics Sir2La showed a slight preference for propionyllysine over acetyllysine and butyryllysine, driven both by KM (14 μM vs 21 μM and 15 μM) and kcat (4.4·10−3 s−1vs 2.5·10−3 s−1 and 1.21·10−3 s−1). Moreover, while NAD+ is a prerequisite for Sir2La-mediated deacylation, Sir2La has very high KM for NAD+ compared to the expected levels of the dinucleotide in L. acidophilus. Sir2La is the first sirtuin from Lactobacillales and of the Gram-positive bacterial subclass of sirtuins to be functionally characterized. The ability to hydrolyze propionyl‐ and butyryllysine emphasizes the relevance of further exploring the role of other short-chain acyl moieties as PTMs.

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Activation of local innate immune signal induces periodontitis in microbiota-dependent manner

FEMS Microbiology Letters ◽

10.1093/femsle/fnz147 ◽

2019 ◽

Vol 366 (12) ◽

Cited By ~ 1

Author(s):

Nan Wang ◽

Dengsheng Xia

Keyword(s):

Alveolar Bone ◽

Chronic Inflammatory Disease ◽

Systemic Administration ◽

Innate Immune ◽

Dependent Manner ◽

Local Inflammation ◽

Tlr2 Activation ◽

The Difference ◽

The Relationship

ABSTRACT Periodontitis is a chronic inflammatory disease. Both inflammation and dysbiosis have been implicated in periodontitis development. However, the relationship between local inflammation and dysbiosis, and the precise roles of local inflammation in periodontitis are not well-elucidated. In present study, we explored the role of local inflammation in periodontitis. We established a periodontitis model by administration of Pam3CSK4 to local oral area and compared the difference of outcome between local and systemic administration. We monitored the pro-inflammatory cytokine expression, local inflammation and alveolar bone loss. We also evaluated the dysbiosis, NF-κB activation. Local but not systemic administration of Pam3CSK4-induced pro-inflammatory cytokines productions and finally resulted in periodontitis. Pam3CSK4 caused dysbiosis and promoted Porphyromonas gingivalis growth. The bacterial growth and NF-κB activation were required for Pam3CSK4-induced periodontitis. We evaluated the effect of local inflammation by inducing TLR2 activation on dysbiosis and periodontitis. Activation of local innate immune signal induces periodontitis in microbiota-dependent manner.

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CD14 Mediates Phagocytic Activity during the Granulocytic Differentiation Process in Acute Promyelocytic Leukemia Cells

Blood ◽

10.1182/blood.v124.21.4955.4955 ◽

2014 ◽

Vol 124 (21) ◽

pp. 4955-4955 ◽

Cited By ~ 1

Author(s):

Hui-Chi Hsu ◽

Wen-Hui Tsai ◽

Yu-Chieh Lin

Keyword(s):

Phagocytic Activity ◽

Promyelocytic Leukemia ◽

Time Dependent ◽

Apoptotic Cells ◽

Dependent Manner ◽

Atra Treatment ◽

Granulocytic Differentiation ◽

Nb4 Cells ◽

Pre Treatment

Abstract All-trans retinoic acid (ATRA) can induce acute promyelocytic leukemia (APL) cells differentiation into mature granulocytes. CD14 and Toll-like receptor 4 (TLR-4) play an important role in the phagocytic activity of macrophage, however, their role during granulopoiesis is still unclear. In this study, we determined the role of CD14/TLR-4 in the development of phagocytic activity in NB4 APL cells after induction into the process of granulocytic differentiation by ATRA. Flow cytometry analysis demonstrate that, during ATRA treatment for 6 days, the phagocytic activity of NB4 cells in engulfing either fluorescein-latex beads or idarubicin-induced apoptotic cells increased in a time-dependent manner, and the level of CD14 expression on NB4 cells was also significantly increased in a time dependent manner, though its level was only minimally expressed in ATRA-untreated NB4 cells. However, TLR-4 was constitutionally expressed in ATRA-untreated cells and its level did not changed significantly during the first 5 days of ATRA treatment. Further study demonstrates that the phagocytic activity of ATRA-NB4 cells was significantly inhibited by pre-treating cells with antibodies specific to either CD14 or TLR-4 before phagocytosis assay. In exploring the role of CD14/TLR4 associated signal transduction mediators, NF-κB and IRF-3, we further demonstrate that the phagocytic activity of ATRA-NB4 cells in engulfing beads was significantly inhibited when cells were pretreated with either a NF-κB inhibitor (BAY 11-7082) or an IRF-3 inhibitor (SP600125). However, this activity in engulfing apoptotic cells was only significantly inhibited by pretreatment with BAY11-7082, but not by pre-treatment with SP600125. Finally, our results indicate that the level of CD14(+) microparticles (MPs) released by ATRA-NB4 cells was significantly enhanced when those cells were induced into the process of apoptosis by pre-treatment with idarubicin. Moreover, by incubation with MPs derived from apoptotic ATRA-NB4 cells, the phagocytic activity of living ATRA-NB4 cells in engulfing apoptotic cells was significantly enhanced, and this phagocytic activity was also significantly inhibited by pre-treating MPs with antibody specific to CD14 before phagocytic assay. We conclude that CD14 contributes to the phagocytic activity of APL cells during the process of granulocytic differentiation. Disclosures No relevant conflicts of interest to declare.

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