scholarly journals Scavenger receptor A1 participates in the phagocytosis of Leptospira interrogans and leads to subsequent high inflammatory responses and bacterial dissemination in leptospirosis

2020 ◽  
Author(s):  
Yanchun Wang ◽  
Xia Fan ◽  
Lin Du ◽  
Boyu Liu ◽  
Haihan Xiao ◽  
...  
Keyword(s):  
Immune Response ◽  
Cytokine Production ◽  
Inflammatory Responses ◽  
Scavenger Receptor ◽  
Severe Infection ◽  
Innate Immune ◽  
Bacterial Dissemination ◽  
Inflammatory Activation ◽  
Severe Jaundice

AbstractLeptospirosis, caused by pathogenic Leptospira species, has emerged as a widespread zoonotic disease worldwide. Macrophages mediate the elimination of pathogens through phagocytosis and cytokine production. Scavenger receptor A1 (SR-A1), one of the critical receptors mediating this process, plays a complicated role in innate immunity. However, the role of SR-A1 in the immune response against pathogenic Leptospira invasion is unknown. In the present study, we found that SR-A1 is an important nonopsonic phagocytic receptor on murine macrophages for Leptospira. We also found that leptospiral LPS is the ligand of SR-A1. However, intraperitoneal injection of leptospires into WT mice presented with more severe jaundice, subcutaneous hemorrhaging, and higher bacteria burdens in blood and tissues than that of SR-A1-/- mice. Exacerbated cytokine and inflammatory mediator levels were also observed in WT mice and higher recruited macrophages in the liver than those of SR-A1-/- mice. Our findings collectively reveal that although beneficial in the uptake of Leptospira by macrophage, SR-A1 might be exploited by Leptospira to promote bacterial dissemination and modulate inflammatory activation, which causes a more severe infection in the host. These results provide our new insights into the innate immune response during early infection by L. interrogans.

Therapeutic Potentials of Scavenger Receptor CD36 Mediated Innate Immune Responses Against Infectious and Non-Infectious Diseases

2020 ◽  
Vol 17 (3) ◽  
pp. 299-317
Author(s):  
Sooram Banesh ◽  
Vishal Trivedi
Keyword(s):  
Immune Response ◽  
Infectious Diseases ◽  
Innate Immune Response ◽  
Scavenger Receptor ◽  
Innate Immune ◽  
Innate Immune Responses ◽  
Different Types ◽  
Cytosolic Domains ◽  
Exogenous Ligands

CD36 is a multifunctional glycoprotein, expressed in different types of cells and known to play a significant role in the pathophysiology of the host. The structural studies revealed that the scavenger receptor consists of short cytosolic domains, two transmembrane domains, and a large ectodomain. The ectodomain serves as a receptor for a diverse number of endogenous and exogenous ligands. The CD36-specific ligands are involved in regulating the immune response during infectious and non-infectious diseases in the host. The role of CD36 in regulating the innate immune response during Pneumonia, Tuberculosis, Malaria, Leishmaniasis, HIV, and Sepsis in a ligand- mediated fashion. Apart from infectious diseases, it is also considered to be involved in metabolic disorders such as Atherosclerosis, Alzheimer’s, cancer, and Diabetes. The ligand binding to scavenger receptor modulates the CD36 down-stream innate immune response, and it can be exploited to design suitable immuno-modulators. Hence, the current review focused on the role of the CD36 in innate immune response and therapeutic potentials of novel heterocyclic compounds as CD36 ligands during infectious and non-infectious diseases.

scholarly journals Bacterial Cyclic Dinucleotides and the cGAS–cGAMP–STING Pathway: A Role in Periodontitis?

Pathogens ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 675
Author(s):  
Samira Elmanfi ◽  
Mustafa Yilmaz ◽  
Wilson W. S. Ong ◽  
Kofi S. Yeboah ◽  
Herman O. Sintim ◽  
...  
Keyword(s):  
Immune Response ◽  
Periodontal Disease ◽  
Innate Immune ◽  
Host Cells ◽  
Type I Interferons ◽  
Type I ◽  
Vaccine Adjuvants ◽  
Cyclic Dinucleotides ◽  
Sting Pathway

Host cells can recognize cytosolic double-stranded DNAs and endogenous second messengers as cyclic dinucleotides—including c-di-GMP, c-di-AMP, and cGAMP—of invading microbes via the critical and essential innate immune signaling adaptor molecule known as STING. This recognition activates the innate immune system and leads to the production of Type I interferons and proinflammatory cytokines. In this review, we (1) focus on the possible role of bacterial cyclic dinucleotides and the STING/TBK1/IRF3 pathway in the pathogenesis of periodontal disease and the regulation of periodontal immune response, and (2) review and discuss activators and inhibitors of the STING pathway as immune response regulators and their potential utility in the treatment of periodontitis. PubMed/Medline, Scopus, and Web of Science were searched with the terms “STING”, “TBK 1”, “IRF3”, and “cGAS”—alone, or together with “periodontitis”. Current studies produced evidence for using STING-pathway-targeting molecules as part of anticancer therapy, and as vaccine adjuvants against microbial infections; however, the role of the STING/TBK1/IRF3 pathway in periodontal disease pathogenesis is still undiscovered. Understanding the stimulation of the innate immune response by cyclic dinucleotides opens a new approach to host modulation therapies in periodontology.

scholarly journals Terminal uridyltransferase 7 regulates TLR4-triggered inflammation by controlling Regnase-1 mRNA uridylation and degradation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Chia-Ching Lin ◽  
Yi-Ru Shen ◽  
Chi-Chih Chang ◽  
Xiang-Yi Guo ◽  
Yun-Yun Young ◽  
...  
Keyword(s):  
Posttranscriptional Regulation ◽  
Inflammatory Responses ◽  
Rna Stability ◽  
Innate Immune ◽  
Stem Loop ◽  
Stem Loop Structure ◽  
Tlr4 Activation ◽  
Harmful Effects ◽  
Different Levels

AbstractDifferent levels of regulatory mechanisms, including posttranscriptional regulation, are needed to elaborately regulate inflammatory responses to prevent harmful effects. Terminal uridyltransferase 7 (TUT7) controls RNA stability by adding uridines to its 3′ ends, but its function in innate immune response remains obscure. Here we reveal that TLR4 activation induces TUT7, which in turn selectively regulates the production of a subset of cytokines, including Interleukin 6 (IL-6). TUT7 regulates IL-6 expression by controlling ribonuclease Regnase-1 mRNA (encoded by Zc3h12a gene) stability. Mechanistically, TLR4 activation causes TUT7 to bind directly to the stem-loop structure on Zc3h12a 3′-UTR, thereby promotes Zc3h12a uridylation and degradation. Zc3h12a from LPS-treated TUT7-sufficient macrophages possesses increased oligo-uridylated ends with shorter poly(A) tails, whereas oligo-uridylated Zc3h12a is significantly reduced in Tut7-/- cells after TLR4 activation. Together, our findings reveal the functional role of TUT7 in sculpting TLR4-driven responses by modulating mRNA stability of a selected set of inflammatory mediators.

Intestinal dysbiosis augments liver disease progression via NLRP3 in a murine model of primary sclerosing cholangitis

Gut ◽  
2019 ◽  
Vol 68 (8) ◽  
pp. 1477-1492 ◽  
Author(s):  
Lijun Liao ◽  
Kai Markus Schneider ◽  
Eric J C Galvez ◽  
Mick Frissen ◽  
Hanns-Ulrich Marschall ◽  
...  
Keyword(s):  
Immune Response ◽  
Liver Injury ◽  
Sclerosing Cholangitis ◽  
Functional Role ◽  
Innate Immune ◽  
Caspase 8 ◽  
Inflammasome Activation ◽  
Intestinal Dysbiosis ◽  
Nlrp3 Inflammasome Activation

ObjectiveThere is a striking association between human cholestatic liver disease (CLD) and inflammatory bowel disease. However, the functional implications for intestinal microbiota and inflammasome-mediated innate immune response in CLD remain elusive. Here we investigated the functional role of gut–liver crosstalk for CLD in the murine Mdr2 knockout (Mdr2−/−) model resembling human primary sclerosing cholangitis (PSC).DesignMale Mdr2−/−, Mdr2−/− crossed with hepatocyte-specific deletion of caspase-8 (Mdr2−/−/Casp8∆hepa) and wild-type (WT) control mice were housed for 8 or 52 weeks, respectively, to characterise the impact of Mdr2 deletion on liver and gut including bile acid and microbiota profiling. To block caspase activation, a pan-caspase inhibitor (IDN-7314) was administered. Finally, the functional role of Mdr2−/−-associated intestinal dysbiosis was studied by microbiota transfer experiments.ResultsMdr2−/− mice displayed an unfavourable intestinal microbiota signature and pronounced NLRP3 inflammasome activation within the gut–liver axis. Intestinal dysbiosis in Mdr2−/− mice prompted intestinal barrier dysfunction and increased bacterial translocation amplifying the hepatic NLRP3-mediated innate immune response. Transfer of Mdr2−/− microbiota into healthy WT control mice induced significant liver injury in recipient mice, highlighting the causal role of intestinal dysbiosis for disease progression. Strikingly, IDN-7314 dampened inflammasome activation, ameliorated liver injury, reversed serum bile acid profile and cholestasis-associated microbiota signature.ConclusionsMDR2-associated cholestasis triggers intestinal dysbiosis. In turn, translocation of endotoxin into the portal vein and subsequent NLRP3 inflammasome activation contribute to higher liver injury. This process does not essentially depend on caspase-8 in hepatocytes, but can be blocked by IDN-7314.

scholarly journals The role of beneficial bacteria wall elasticity in regulating innate immune response

2015 ◽  
Vol 6 (1) ◽  
Author(s):  
Viktoria V. Мokrozub ◽  
Liudmyla M. Lazarenko ◽  
Liubov M. Sichel ◽  
Lidia P. Babenko ◽  
Petro M. Lytvyn ◽  
...  
Keyword(s):  
Immune Response ◽  
Innate Immune Response ◽  
Innate Immune ◽  
Beneficial Bacteria

scholarly journals microRNA-210 and microRNA-3570 Negatively Regulate NF-κB-Mediated Inflammatory Responses by Targeting RIPK2 in Teleost Fish

2021 ◽  
Vol 12 ◽  
Author(s):  
Hui Su ◽  
Renjie Chang ◽  
Weiwei Zheng ◽  
Yuena Sun ◽  
Tianjun Xu
Keyword(s):  
Immune Response ◽  
Signaling Pathway ◽  
Innate Immune Response ◽  
Inflammatory Responses ◽  
Innate Immune ◽  
Regulatory Role ◽  
Inflammatory Cytokine Production ◽  
Immune Genes ◽  
Lower Vertebrates ◽  
Antimicrobial Immunity

Pathogen infection can cause the production of inflammatory cytokines, which are key mediators that cause the host’s innate immune response. Therefore, proper regulation of immune genes associated with inflammation is essential for immune response. Among them, microRNAs (miRNAs) as gene regulator have been widely reported to be involved in the innate immune response of mammals. However, the regulatory network in which miRNAs are involved in the development of inflammation is largely unknown in lower vertebrates. Here, we identified two miRNAs from miiuy croaker (Miichthys miiuy), miR-210 and miR-3570, which play a negative regulatory role in host antibacterial immunity. We found that the expressions of miR-210 and miR-3570 were significantly upregulated under the stimulation of Gram-negative bacterium vibrio harveyi and LPS (lipopolysaccharide). Induced miR-210 and miR-3570 inhibit inflammatory cytokine production by targeting RIPK2, thereby avoiding excessive inflammation. In particular, we found that miR-210 and miR-3570 negatively regulate antimicrobial immunity by regulating the RIPK2-mediated NF-κB signaling pathway. The collective results indicated that both miRNAs are used as negative feedback regulators to regulate RIPK2-mediated NF-κB signaling pathway and thus play a regulatory role in bacteria-induced inflammatory response.

Sign in / Sign up

Export Citation Format

Share Document