scholarly journals Asymptomatic SARS-CoV-2 infection: Is it all about being refractile to innate immune sensing of viral spare-parts? – Clues from exotic animal reservoirs

2020 ◽  
Author(s):  
Esaki M Shankar ◽  
Karlhans F Che ◽  
Yean K Yong ◽  
A S Smiline Girija ◽  
Vijayakumar Velu ◽  
...  

Abstract A vast proportion of coronavirus disease 2019 (COVID-19) individuals remain asymptomatic and can shed severe acute respiratory syndrome (SARS-CoV) type 2 virus to transmit the infection, which also explains the exponential increase in the number of COVID-19 cases globally. Furthermore, the rate of recovery rates from clinical COVID-19 in certain pockets of the globe is surprisingly high. Based on published reports and available literature, here, we speculated a few immunovirological mechanisms as to why a vast majority of individuals remain asymptomatic similar to exotic animal (bats and pangolins) reservoirs that remain refractile to disease development despite carrying a huge load of diverse insidious viral species, and whether such evolutionary advantage would unveil therapeutic strategies against human COVID-19 infection. Understanding the unique mechanisms that exotic animal species employ to achieve viral control, as well as inflammatory regulation, appears to hold key clues to the development of therapeutic versatility against COVID-19.

Viruses ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 567
Author(s):  
Renate König ◽  
Carsten Münk

In this Special Issue, a wide variety of original and review articles provide a timely overview of how viruses are recognized by and evade from cellular innate immunity, which represents the first line of defense against viruses [...]


2018 ◽  
Author(s):  
Priya Hari ◽  
Fraser R. Millar ◽  
Nuria Tarrats ◽  
Jodie Birch ◽  
Curtis J. Rink ◽  
...  

ABSTRACTCellular senescence is a stress response program characterised by a robust cell cycle arrest and the induction of a pro-inflammatory senescence-associated secretory phenotype (SASP) that is triggered through an unknown mechanism. Here, we show that during oncogene-induced senescence (OIS), the Toll-like receptor TLR2 and its partner TLR10 are key mediators of senescence in vitro and in murine models. TLR2 promotes cell cycle arrest by regulating the tumour suppressors p53-p21CIP1, p16INK4a and p15INK4b, and regulates the SASP through the induction of the acute-phase serum amyloids A1 and A2 (A-SAA) that, in turn, function as the damage associated molecular patterns (DAMPs) signalling through TLR2 in OIS. Finally, we found evidence that the cGAS-STING cytosolic DNA sensing pathway primes TLR2 and A-SAA expression in OIS. In summary, we report that innate immune sensing of senescence-associated DAMPs by TLR2 controls the SASP and reinforces the cell cycle arrest program in OIS.


2019 ◽  
Vol 216 (5) ◽  
pp. 1199-1213 ◽  
Author(s):  
Matthieu Gratia ◽  
Mathieu P. Rodero ◽  
Cécile Conrad ◽  
Elias Bou Samra ◽  
Mathieu Maurin ◽  
...  

Cellular innate immune sensors of DNA are essential for host defense against invading pathogens. However, the presence of self-DNA inside cells poses a risk of triggering unchecked immune responses. The mechanisms limiting induction of inflammation by self-DNA are poorly understood. BLM RecQ–like helicase is essential for genome integrity and is deficient in Bloom syndrome (BS), a rare genetic disease characterized by genome instability, accumulation of micronuclei, susceptibility to cancer, and immunodeficiency. Here, we show that BLM-deficient fibroblasts show constitutive up-regulation of inflammatory interferon-stimulated gene (ISG) expression, which is mediated by the cGAS–STING–IRF3 cytosolic DNA–sensing pathway. Increased DNA damage or down-regulation of the cytoplasmic exonuclease TREX1 enhances ISG expression in BLM-deficient fibroblasts. cGAS-containing cytoplasmic micronuclei are increased in BS cells. Finally, BS patients demonstrate elevated ISG expression in peripheral blood. These results reveal that BLM limits ISG induction, thus connecting DNA damage to cellular innate immune response, which may contribute to human pathogenesis.


2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Miao Tian ◽  
Xiumei Wang ◽  
Jihong Sun ◽  
Wenlong Lin ◽  
Lumin Chen ◽  
...  

AbstractOccurrence of Colorectal cancer (CRC) is relevant with gut microbiota. However, role of IRF3, a key signaling mediator in innate immune sensing, has been barely investigated in CRC. Here, we unexpectedly found that the IRF3 deficient mice are hyper-susceptible to the development of intestinal tumor in AOM/DSS and Apcmin/+ models. Genetic ablation of IRF3 profoundly promotes the proliferation of intestinal epithelial cells via aberrantly activating Wnt signaling. Mechanically, IRF3 in resting state robustly associates with the active β-catenin in the cytoplasm, thus preventing its nuclear translocation and cell proliferation, which can be relieved upon microbe-induced activation of IRF3. In accordance, the survival of CRC is clinically correlated with the expression level of IRF3. Therefore, our study identifies IRF3 as a negative regulator of the Wnt/β-catenin pathway and a potential prognosis marker for Wnt-related tumorigenesis, and describes an intriguing link between gut microbiota and CRC via the IRF3-β-catenin axis.


iScience ◽  
2020 ◽  
Vol 23 (7) ◽  
pp. 101257 ◽  
Author(s):  
Julia Manzetti ◽  
Fabian H. Weissbach ◽  
Fabrice E. Graf ◽  
Gunhild Unterstab ◽  
Marion Wernli ◽  
...  

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