scholarly journals A conserved β-bulge glycine residue facilitates folding and increases stability of the mouse α-defensin cryptdin-4

2021 ◽  
Author(s):  
Richard J. Clark ◽  
Thanh Huyen Phan ◽  
Angela Song ◽  
André J. Ouellette ◽  
Anne C. Conibear ◽  
...  
Keyword(s):  
Immune Responses ◽  
Bioactive Peptides ◽  
Three Dimensional ◽  
Antibacterial Activities ◽  
Gram Negative Bacteria ◽  
Intestinal Fluid ◽  
Simulated Intestinal Fluid ◽  
Glycine Residue ◽  
Adaptive Immune

Defensins are key components of both innate and adaptive immune responses to pathogens. Cryptdins are mouse alpha-defensins that are secreted from Paneth cells in the small intestine and have disulfide-stabilised structures and antibacterial activities against both Gram-positive and Gram-negative bacteria. The folding and three-dimensional structures of alpha-defensins are thought to depend on a conserved glycine residue that forms a β-bulge. Here we investigated the role of this conserved glycine at position 19 of cryptdin-4 (Crp4) in terms of the folding, structure and stability. A Crp4 variant with D-Ala at position 19 folded efficiently, was stabilised by a large number of hydrogen bonds, and resisted proteolysis in simulated intestinal fluid. Although a variant with L-Ala at position 19 was able to adopt the correct fold, it showed less efficient folding and was degraded more rapidly than the D-Ala variant. These results demonstrate the key role that glycine residues can have in folding of bioactive peptides and can provide insights to guide design of stable antimicrobial peptides that fold efficiently.

scholarly journals Role of the Innate Immunity Signaling Pathway in the Pathogenesis of Sjögren’s Syndrome

2021 ◽  
Vol 22 (6) ◽  
pp. 3090
Author(s):  
Toshimasa Shimizu ◽  
Hideki Nakamura ◽  
Atsushi Kawakami
Keyword(s):  
Immune Responses ◽  
Sjögren's Syndrome ◽  
Sjogren’S Syndrome ◽  
Sjogren's Syndrome ◽  
Innate Immune ◽  
Type I ◽  
Type I Ifn ◽  
Adaptive Immune ◽  
Sjögren‘S Syndrome

Sjögren’s syndrome (SS) is a systemic autoimmune disease characterized by chronic inflammation of the salivary and lacrimal glands and extra-glandular lesions. Adaptive immune response including T- and B-cell activation contributes to the development of SS. However, its pathogenesis has not yet been elucidated. In addition, several patients with SS present with the type I interferon (IFN) signature, which is the upregulation of the IFN-stimulated genes induced by type I IFN. Thus, innate immune responses including type I IFN activity are associated with SS pathogenesis. Recent studies have revealed the presence of activation pattern recognition receptors (PRRs) including Toll-like receptors, RNA sensor retinoic acid-inducible gene I and melanoma differentiation-associated gene 5, and inflammasomes in infiltrating and epithelial cells of the salivary glands among patients with SS. In addition, the activation of PRRs via the downstream pathway such as the type I IFN signature and nuclear factor kappa B can directly cause organ inflammation, and it is correlated with the activation of adaptive immune responses. Therefore, this study assessed the role of the innate immune signal pathway in the development of inflammation and immune abnormalities in SS.

scholarly journals ATP Induces IL-1βSecretion inNeisseria gonorrhoeae-Infected Human Macrophages by a Mechanism Not Related to the NLRP3/ASC/Caspase-1 Axis

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Killen García ◽  
Gisselle Escobar ◽  
Pablo Mendoza ◽  
Caroll Beltran ◽  
Claudio Perez ◽  
...  
Keyword(s):  
Immune Responses ◽  
Immune Evasion ◽  
Transcriptional Activation ◽  
Pore Formation ◽  
Human Monocyte ◽  
Positive Staining ◽  
Adaptive Immune Responses ◽  
Adaptive Immune ◽  
Caspase 1

Neisseria gonorrhoeae(Ngo) has developed multiple immune evasion mechanisms involving the innate and adaptive immune responses. Recent findings have reported that Ngo reduces the IL-1βsecretion of infected human monocyte-derived macrophages (MDM). Here, we investigate the role of adenosine triphosphate (ATP) in production and release of IL-1βin Ngo-infected MDM. We found that the exposure of Ngo-infected MDM to ATP increases IL-1βlevels about ten times compared with unexposed Ngo-infected MDM (P<0.01). However, we did not observe any changes in inflammasome transcriptional activation of speck-like protein containing a caspase recruitment domain (CARD) (ASC,P>0.05) and caspase-1 (CASP1,P>0.05). In addition, ATP was not able to modify caspase-1 activity in Ngo-infected MDM but was able to increase pyroptosis (P>0.01). Notably ATP treatment defined an increase of positive staining for IL-1βwith a distinctive intracellular pattern of distribution. Collectively, these data demonstrate that ATP induces IL-1βsecretion by a mechanism not related to the NLRP3/ASC/caspase-1 axis and likely is acting at the level of vesicle trafficking or pore formation.

Role of DAP12 in Innate and Adaptive Immune Responses

2003 ◽  
Vol 9 (1) ◽  
pp. 7-10 ◽  
Author(s):  
Naoko Aoki ◽  
Shoji Kimura ◽  
Zhou Xing
Keyword(s):  
Immune Responses ◽  
Adaptive Immune Responses ◽  
Adaptive Immune

scholarly journals A functional spleen contributes to afucosylated IgG in humans

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Iwona Wojcik ◽  
David E. Schmidt ◽  
Lisa A. de Neef ◽  
Minke A. E. Rab ◽  
Bob Meek ◽  
...  
Keyword(s):  
Immune Responses ◽  
Viral Infections ◽  
Immune Cell ◽  
Lymphoid Organ ◽  
Immune Effector ◽  
Adaptive Immune ◽  
Wide Range ◽  
Humoral Responses ◽  
First Time

AbstractAs a lymphoid organ, the spleen hosts a wide range of immune cell populations, which not only remove blood-borne antigens, but also generate and regulate antigen-specific immune responses. In particular, the splenic microenvironment has been demonstrated to play a prominent role in adaptive immune responses to enveloped viral infections and alloantigens. During both types of immunizations, antigen-specific immunoglobulins G (IgGs) have been characterized by the reduced amount of fucose present on N-linked glycans of the fragment crystallizable (Fc) region. These glycans are essential for mediating the induction of immune effector functions. Therefore, we hypothesized that a spleen may modulate humoral responses and serve as a preferential site for afucosylated IgG responses, which potentially play a role in immune thrombocytopenia (ITP) pathogenesis. To determine the role of the spleen in IgG-Fc glycosylation, we performed IgG subclass-specific liquid chromatography–mass spectrometry (LC–MS) analysis of Fc glycosylation in a large cohort of individuals splenectomized due to trauma, due to ITP, or spherocytosis. IgG-Fc fucosylation was consistently increased after splenectomy, while no effects for IgG-Fc galactosylation and sialylation were observed. An increase in IgG1- and IgG2/3-Fc fucosylation level upon splenectomy has been reported here for the first time, suggesting that immune responses occurring in the spleen may be particularly prone to generate afucosylated IgG responses. Surprisingly, the level of total IgG-Fc fucosylation was decreased in ITP patients compared to healthy controls. Overall, our results suggest a yet unrecognized role of the spleen in either the induction or maintenance of afucosylated IgG responses by B cells.

scholarly journals Impact of HMGB1/TLR Ligand Complexes on HIV-1 Replication: Possible Role for Flagellin during HIV-1 Infection

2012 ◽  
Vol 2012 ◽  
pp. 1-10 ◽  
Author(s):  
Piotr Nowak ◽  
Samir Abdurahman ◽  
Annica Lindkvist ◽  
Marius Troseid ◽  
Anders Sönnerborg
Keyword(s):  
Immune Responses ◽  
Cpg Odn ◽  
Cell Necrosis ◽  
Adaptive Immune ◽  
Microbial Product ◽  
P24 Antigen ◽  
Culture Supernatants ◽  
Hiv 1

Objective. We hypothesized that HMGB1 in complex with bacterial components, such as flagellin, CpG-ODN, and LPS, promotes HIV-1 replication. Furthermore, we studied the levels of antiflagellin antibodies during HIV-1-infection.Methods. Chronically HIV-1-infected U1 cells were stimulated with necrotic extract/recombinant HMGB1 in complex with TLR ligands or alone. HIV-1 replication was estimated by p24 antigen in culture supernatants 48–72 hours after stimulation. The presence of systemic anti-flagellin IgG was determined in 51 HIV-1-infected patients and 19 controls by immunoblotting or in-house ELISA.Results. Flagellin, LPS, and CpG-ODN induced stronger HIV-1 replication when incubated together with necrotic extract or recombinant HMGB1 than activation by any of the compounds alone. Moreover, the stimulatory effect of necrotic extract was inhibited by depletion of HMGB1. Elevated levels of anti-flagellin antibodies were present in plasma from HIV-1-infected patients and significantly decreased during 2 years of antiretroviral therapy.Conclusions. Our findings implicate a possible role of HGMB1-bacterial complexes, as a consequence of microbial translocation and cell necrosis, for immune activation in HIV-1 pathogenesis. We propose that flagellin is an important microbial product, that modulates viral replication and induces adaptive immune responsesin vivo.

scholarly journals TmSpz4 Plays an Important Role in Regulating the Production of Antimicrobial Peptides in Response to Escherichia coli and Candida albicans Infections

2020 ◽  
Vol 21 (5) ◽  
pp. 1878 ◽  
Author(s):  
Tariku Tesfaye Edosa ◽  
Yong Hun Jo ◽  
Maryam Keshavarz ◽  
Young Min Bae ◽  
Dong Hyun Kim ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Candida Albicans ◽  
Immune Responses ◽  
Fungal Infections ◽  
Larval Survival ◽  
Gram Negative Bacteria ◽  
Functional Importance ◽  
E Coli ◽  
Microbial Infections

Spätzle family proteins activate the Toll pathway and induce antimicrobial peptide (AMP) production against microbial infections. However, the functional importance of Tmspätzle4 (TmSpz4) in the immune response of Tenebrio molitor has not been reported. Therefore, here, we have identified and functionally characterized the role of TmSpz4 against bacterial and fungal infections. We showed that TmSpz4 expression was significantly induced in hemocytes at 6 h post-injection with Escherichia coli, Staphylococcus aureus, and Candida albicans. TmSpz4 knock-down significantly reduced larval survival against E. coli and C. albicans. To understand the reason for the survivability difference, the role of TmSpz4 in AMP production was examined in TmSpz4-silenced larvae following microbe injection. The AMPs that are active against Gram-negative bacteria, including TmTenecin-2, TmTenecin-4, TmAttacin-1a, TmDefensin-2, and TmCecropin-2, were significantly downregulated in response to E. coli in TmSpz4-silenced larvae. Similarly, the expression of TmTenecin-1, TmTenecin-3, TmThaumatin-like protein-1 and -2, TmDefensin-1, TmDefensin-2, and TmCecropin-2 were downregulated in response to C. albicans in TmSpz4-silenced larvae. In addition, the transcription factor NF-κB (TmDorX1 and TmDorX2) expression was significantly suppression in TmSpz4-silenced larvae. In conclusion, these results suggest that TmSpz4 plays a key role in regulating immune responses of T. molitor against to E. coli and C. albicans.

scholarly journals Crosstalk between Dendritic Cells and Immune Modulatory Agents against Sepsis

Genes ◽  
2020 ◽  
Vol 11 (3) ◽  
pp. 323 ◽  
Author(s):  
Guoying Wang ◽  
Xianghui Li ◽  
Lei Zhang ◽  
Abualgasim Elgaili Abdalla ◽  
Tieshan Teng ◽  
...  
Keyword(s):  
Immune Response ◽  
Dendritic Cells ◽  
Immune Responses ◽  
Critical Role ◽  
Innate Immune ◽  
Adaptive Immune Responses ◽  
Adaptive Immune ◽  
Th2 Responses ◽  
Novel Strategy

Dendritic cells (DCs) play a critical role in the immune system which sense pathogens and present their antigens to prime the adaptive immune responses. As the progression of sepsis occurs, DCs are capable of orchestrating the aberrant innate immune response by sustaining the Th1/Th2 responses that are essential for host survival. Hence, an in-depth understanding of the characteristics of DCs would have a beneficial effect in overcoming the obstacle occurring in sepsis. This paper focuses on the role of DCs in the progression of sepsis and we also discuss the reverse sepsis-induced immunosuppression through manipulating the DC function. In addition, we highlight some potent immunotherapies that could be used as a novel strategy in the early treatment of sepsis.

scholarly journals B-1a B Cells that Link the Innate and Adaptive Immune Responses Are Lacking in the Absence of the Spleen

2002 ◽  
Vol 195 (6) ◽  
pp. 771-780 ◽  
Author(s):  
Hedda Wardemann ◽  
Thomas Boehm ◽  
Neil Dear ◽  
Rita Carsetti
Keyword(s):  
B Cells ◽  
Immune Responses ◽  
B Cell ◽  
Innate Immune ◽  
Streptococcal Infections ◽  
Wild Type ◽  
Adaptive Immune ◽  
Encapsulated Bacteria ◽  
Increased Susceptibility

Splenectomized individuals are prone to overwhelming infections with encapsulated bacteria and splenectomy of mice increases susceptibility to streptococcal infections, yet the exact mechanism by which the spleen protects against such infections is unknown. Using congenitally asplenic mice as a model, we show that the spleen is essential for the generation of B-1a cells, a B cell population that cooperates with the innate immune system to control early bacterial and viral growth. Splenectomy of wild-type mice further demonstrated that the spleen is also important for the survival of B-1a cells. Transfer experiments demonstrate that lack of these cells, as opposed to the absence of the spleen per se, is associated with an inability to mount a rapid immune response against streptococcal polysaccharides. Thus, absence of the spleen and the associated increased susceptibility to streptococcal infections is correlated with lack of B-1a B cells. These findings reveal a hitherto unknown role of the spleen in generating and maintaining the B-1a B cell pool.

scholarly journals Cell Intrinsic Roles of Apoptosis-Associated Speck-Like Protein in Regulating Innate and Adaptive Immune Responses

2011 ◽  
Vol 11 ◽  
pp. 2418-2423 ◽  
Author(s):  
Hoda Hassan ◽  
Amal O. Amer
Keyword(s):  
Immune Responses ◽  
Protein Kinases ◽  
Inflammatory Cytokines ◽  
Adaptor Protein ◽  
Adaptive Immune Responses ◽  
Mitogen Activated Protein Kinases ◽  
Adaptive Immune ◽  
Mitogen Activated Protein ◽  
Intrinsic Roles

The role of apoptosis-associated speck-Like protein (ASC) in the assembly of the inflammasome complex within macrophages has been elucidated in several studies. In this particular role, ASC functions as an adaptor protein by linking nod-like receptors (NLRs) and procaspase-1, thereby leading to the activation of caspase-1 to cleave inflammatory cytokines IL-1βand IL-18 and inducing pyroptosis. It has been noted that ASC maintains inflammasome-independent roles, including but not limited to controlling the expression of Dock2 and mitogen-activated protein kinases (MAPK/ERK2) and regulating the NF-κB pathway. This paper will emphasize the major roles of ASC during pathogen infection, the mechanisms by which it mediates inflammation, and discuss its more recently discovered functions.

Sign in / Sign up

Export Citation Format

Share Document