Fibrinolysis and the Immune Response in Trauma

2020 ◽  
Vol 46 (02) ◽  
pp. 176-182
Author(s):  
Robert L. Medcalf ◽  
Charithani B. Keragala ◽  
Dominik F. Draxler
Keyword(s):  
Immune Response ◽  
Traumatic Event ◽  
Optimal Recovery ◽  
Innate Immune ◽  
Fibrinolytic System ◽  
Post Injury ◽  
Antifibrinolytic Agents ◽  
Blood Clots ◽  
Injured Patients

AbstractIt has long been known that the fibrinolytic system becomes activated following trauma. At first glance, this is not at all surprising and would appear to be in response to coagulation and the apparent need to remove blood clots and restore blood flow. However, in a bleeding patient, the opposite is what is actually needed. Therefore, one may ask why the fibrinolytic system gets activated in the first place or is there another purpose? Or is it that the waxing and waning of hemostasis in such severely injured patients creates a “moving target” such that the fibrinolytic system itself is constantly responding to changing circumstances? Depending on the injury modalities and the time point post injury, the fibrinolytic system could be either turned on or off. Various theories now abound that offer new insights into the turmoil and paradoxes associated with the fibrinolytic system in this unique setting and the use of antifibrinolytic agents. While this presents one conundrum, there is also another dimension to add to this discussion that has nothing to do with hemostasis per se but rather with the modulation of other critical processes that are also essential for optimal recovery following severe injury. Indeed, overwhelming data are now supporting an important role of the fibrinolytic system in the removal of necrotic tissue (mortolysis) and as a modulator of the innate immune response. Therefore, what is really going on when the fibrinolytic system decides to go into overdrive and generate plasmin, albeit even briefly after a traumatic event? Moreover, what other consequence may occur when antifibrinolytic agents are administered? This review will address this developing story and will outline a hypothesis that places the fibrinolytic system as a gateway to a myriad of processes that are not only linked to fibrin removal but are also broader players in the modulation of innate immunity.

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.

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 Interferon-Stimulated Genes as Enhancers of Antiviral Innate Immune Signaling

2017 ◽  
Vol 10 (2) ◽  
pp. 85-93 ◽  
Author(s):  
Keaton M. Crosse ◽  
Ebony A. Monson ◽  
Michael R. Beard ◽  
Karla J. Helbig
Keyword(s):  
Immune Response ◽  
Viral Infection ◽  
Innate Immune Response ◽  
Innate Immune ◽  
Regulatory Factor ◽  
Interferon Stimulated Genes ◽  
Innate Immune Signaling ◽  
Recent Advancement ◽  
Antiviral Function

The ability of a host to curb a viral infection is heavily reliant on the effectiveness of an initial antiviral innate immune response, resulting in the upregulation of interferon (IFN) and, subsequently, IFN-stimulated genes (ISGs). ISGs serve to mount an antiviral state within a host cell, and although the specific antiviral function of a number of ISGs has been characterized, the function of many of these ISGs remains to be determined. Recent research has uncovered a novel role for a handful of ISGs, some of them directly induced by IFN regulatory factor 3 in the absence of IFN itself. These ISGs, most with potent antiviral activity, are also able to augment varying arms of the innate immune response to viral infection, thereby strengthening this response. This new understanding of the role of ISGs may, in turn, help the recent advancement of novel therapeutics aiming to augment innate signaling pathways in an attempt to control viral infection and pathogenesis.

scholarly journals CD69 Deficiency Enhances the Host Response to Vaccinia Virus Infection through Altered NK Cell Homeostasis

2016 ◽  
Vol 90 (14) ◽  
pp. 6464-6474 ◽  
Author(s):  
Laura Notario ◽  
Elisenda Alari-Pahissa ◽  
Antonio de Molina ◽  
Pilar Lauzurica
Keyword(s):  
Immune Response ◽  
Infection Control ◽  
Vaccinia Virus ◽  
Nk Cells ◽  
Natural Killer ◽  
Host Response ◽  
Nk Cell ◽  
Innate Immune ◽  
Cell Numbers

ABSTRACTDuring the host response to viral infection, the transmembrane CD69 protein is highly upregulated in all immune cells. We have studied the role of CD69 in the murine immune response to vaccinia virus (VACV) infection, and we report that the absence of CD69 enhances protection against VACV at both short and long times postinfection in immunocompetent and immunodeficient mice. Natural killer (NK) cells were implicated in the increased infection control, since the differences were greatly diminished when NK cells were depleted. This role of NK cells was not based on an altered NK cell reactivity, since CD69 did not affect the NK cell activation threshold in response to major histocompatibility complex class I NK cell targets or protein kinase C activation. Instead, NK cell numbers were increased in the spleen and peritoneum of CD69-deficient infected mice. That was not just secondary to better infection control in CD69-deficient mice, since NK cell numbers in the spleens and the blood of uninfected CD69−/−mice were already augmented. CD69-deficient NK cells from infected mice did not have an altered proliferation capacity. However, a lower spontaneous cell death rate was observed for CD69−/−lymphocytes. Thus, our results suggest that CD69 limits the innate immune response to VACV infection at least in part through cell homeostatic survival.IMPORTANCEWe show that increased natural killer (NK) cell numbers augment the host response and survival after infection with vaccinia virus. This phenotype is found in the absence of CD69 in immunocompetent and immunodeficient hosts. As part of the innate immune system, NK lymphocytes are activated and participate in the defense against infection. Several studies have focused on the contribution of NK cells to protection against infection with vaccinia virus. In this study, it was demonstrated that the augmented early NK cell response in the absence of CD69 is responsible for the increased protection seen during infection with vaccinia virus even at late times of infection. This work indicates that the CD69 molecule may be a target of therapy to augment the response to poxvirus infection.

Role of miRNA-146a in the regulation of the innate immune response and cancer

2008 ◽  
Vol 36 (6) ◽  
pp. 1211-1215 ◽  
Author(s):  
Andrew E. Williams ◽  
Mark M. Perry ◽  
Sterghios A. Moschos ◽  
Hanna M. Larner-Svensson ◽  
Mark A. Lindsay
Keyword(s):  
Immune Response ◽  
Innate Immune Response ◽  
Mammalian Cells ◽  
Mrna Translation ◽  
Nuclear Factor Κb ◽  
Causal Link ◽  
Innate Immune ◽  
Major Function ◽  
Biological Responses

In mammalian cells, miRNAs (microRNAs) are the most abundant family of small non-coding RNAs that regulate mRNA translation through the RNA interference pathway. In general, it appears that the major function of miRNAs is in development, differentiation and homoeostasis, which is indicated by studies showing aberrant miRNA expression during the development of cancer. Interestingly, changes in the expression of miR-146a have been implicated in both the development of multiple cancers and in the negative regulation of inflammation induced via the innate immune response. Furthermore, miR-146a expression is driven by the transcription factor NF-κB (nuclear factor κB), which has been implicated as an important causal link between inflammation and carcinogenesis. In the present article, we review the evidence for a role of miR-146a in innate immunity and cancer and assess whether changes in miR-146a might link these two biological responses.

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