scholarly journals Implications of Innate Immunity in Post-Acute Sequelae of Non-Persistent Viral Infections

Cells ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 2134
Author(s):  
Maximilian Hirschenberger ◽  
Victoria Hunszinger ◽  
Konstantin Maria Johannes Sparrer
Keyword(s):  
Immune Responses ◽  
Acute Phase ◽  
Viral Infections ◽  
Chronic Fatigue ◽  
Neurological Complications ◽  
Treatment And Prevention ◽  
Persistent Viruses ◽  
Wide Range ◽  
The Impact ◽  
Persistent Viral Infections

Non-persistent viruses classically cause transient, acute infections triggering immune responses aimed at the elimination of the pathogen. Successful viruses evolved strategies to manipulate and evade these anti-viral defenses. Symptoms during the acute phase are often linked to dysregulated immune responses that disappear once the patient recovers. In some patients, however, symptoms persist or new symptoms emerge beyond the acute phase. Conditions resulting from previous transient infection are termed post-acute sequelae (PAS) and were reported for a wide range of non-persistent viruses such as rota-, influenza- or polioviruses. Here we provide an overview of non-persistent viral pathogens reported to be associated with diverse PAS, among them chronic fatigue, auto-immune disorders, or neurological complications and highlight known mechanistic details. Recently, the emergence of post-acute sequelae of COVID-19 (PASC) or long COVID highlighted the impact of PAS. Notably, PAS of non-persistent infections often resemble symptoms of persistent viral infections, defined by chronic inflammation. Inflammation maintained after the acute phase may be a key driver of PAS of non-persistent viruses. Therefore, we explore current insights into aberrant activation of innate immune signaling pathways in the post-acute phase of non-persistent viruses. Finally, conclusions are drawn and future perspectives for treatment and prevention of PAS are discussed.

scholarly journals SARS-CoV-2 and the Nervous System: From Clinical Features to Molecular Mechanisms

2020 ◽  
Vol 21 (15) ◽  
pp. 5475 ◽  
Author(s):  
Manuela Pennisi ◽  
Giuseppe Lanza ◽  
Luca Falzone ◽  
Francesco Fisicaro ◽  
Raffaele Ferri ◽  
...  
Keyword(s):  
Nervous System ◽  
Molecular Mechanisms ◽  
Neuronal Damage ◽  
Neurological Complications ◽  
Neurological Manifestations ◽  
Wide Range ◽  
Inflammatory State ◽  
Acute Polyneuropathy ◽  
The Central Nervous System ◽  
The Impact

Increasing evidence suggests that Severe Acute Respiratory Syndrome-coronavirus-2 (SARS-CoV-2) can also invade the central nervous system (CNS). However, findings available on its neurological manifestations and their pathogenic mechanisms have not yet been systematically addressed. A literature search on neurological complications reported in patients with COVID-19 until June 2020 produced a total of 23 studies. Overall, these papers report that patients may exhibit a wide range of neurological manifestations, including encephalopathy, encephalitis, seizures, cerebrovascular events, acute polyneuropathy, headache, hypogeusia, and hyposmia, as well as some non-specific symptoms. Whether these features can be an indirect and unspecific consequence of the pulmonary disease or a generalized inflammatory state on the CNS remains to be determined; also, they may rather reflect direct SARS-CoV-2-related neuronal damage. Hematogenous versus transsynaptic propagation, the role of the angiotensin II converting enzyme receptor-2, the spread across the blood-brain barrier, the impact of the hyperimmune response (the so-called “cytokine storm”), and the possibility of virus persistence within some CNS resident cells are still debated. The different levels and severity of neurotropism and neurovirulence in patients with COVID-19 might be explained by a combination of viral and host factors and by their interaction.

scholarly journals The RhoA-ROCK pathway in the regulation of T and B cell responses

F1000Research ◽  
2016 ◽  
Vol 5 ◽  
pp. 2295 ◽  
Author(s):  
Edd Ricker ◽  
Luvana Chowdhury ◽  
Woelsung Yi ◽  
Alessandra B. Pernis
Keyword(s):  
Immune Responses ◽  
Biological Processes ◽  
Dynamic Interactions ◽  
Cell Responses ◽  
Important Mediator ◽  
Downstream Effectors ◽  
Wide Range ◽  
Response To Stress ◽  
The Impact ◽  
Rho Kinases

Effective immune responses require the precise regulation of dynamic interactions between hematopoietic and non-hematopoietic cells. The Rho subfamily of GTPases, which includes RhoA, is rapidly activated downstream of a diverse array of biochemical and biomechanical signals, and is emerging as an important mediator of this cross-talk. Key downstream effectors of RhoA are the Rho kinases, or ROCKs. The ROCKs are two serine-threonine kinases that can act as global coordinators of a tissue’s response to stress and injury because of their ability to regulate a wide range of biological processes. Although the RhoA-ROCK pathway has been extensively investigated in the non-hematopoietic compartment, its role in the immune system is just now becoming appreciated. In this commentary, we provide a brief overview of recent findings that highlight the contribution of this pathway to lymphocyte development and activation, and the impact that dysregulation in the activation of RhoA and/or the ROCKs may exert on a growing list of autoimmune and lymphoproliferative disorders.

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 The Biological Context of C-Reactive Protein as a Prognostic Marker in Renal Cell Carcinoma: Studies on the Acute Phase Cytokine Profile

Cancers ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1961 ◽  
Author(s):  
Helene Hersvik Aarstad ◽  
Gigja Guðbrandsdottir ◽  
Karin M. Hjelle ◽  
Leif Bostad ◽  
Øystein Bruserud ◽  
...  
Keyword(s):  
Cancer Patients ◽  
Renal Cancer ◽  
Acute Phase ◽  
High Serum ◽  
Cytokine Profile ◽  
Phase Reaction ◽  
C Reactive Protein ◽  
Reactive Protein ◽  
Wide Range ◽  
The Impact

High serum levels of the acute phase protein C-reactive protein (CRP) are associated with an adverse prognosis in renal cancer. The acute phase reaction is cytokine-driven and includes a wide range of inflammatory mediators. This overall profile of the response depends on the inducing event and can also differ between patients. We investigated an extended acute phase cytokine profile for 97 renal cancer patients. Initial studies showed that the serum CRP levels had an expected prognostic association together with tumor size, stage, nuclear grading, and Leibovich score. Interleukin (IL)6 family cytokines, IL1 subfamily mediators, and tumor necrosis factor (TNF)α can all be drivers of the acute phase response. Initial studies suggested that serum IL33Rα (the soluble IL33 receptor α chain) levels were also associated with prognosis, although the impact of IL33Rα is dependent on the overall cytokine profile, including seven IL6 family members (IL6, IL6Rα, gp130, IL27, IL31, CNTF, and OSM), two IL1 subfamily members (IL1RA and IL33Rα), and TNFα. We identified a patient subset characterized by particularly high levels of IL6, IL33Rα, and TNFα alongside an adverse prognosis. Thus, the acute phase cytokine reaction differs between renal cancer patients, and differences in the acute phase cytokine profile are associated with prognosis.

scholarly journals The Impact of Radiation-Induced DNA Damage on cGAS-STING-Mediated Immune Responses to Cancer

2020 ◽  
Vol 21 (22) ◽  
pp. 8877
Author(s):  
Quinn Storozynsky ◽  
Mary M. Hitt
Keyword(s):  
Dna Damage ◽  
Immune Responses ◽  
Treatment Strategies ◽  
Cytotoxic T Cell ◽  
Innate Immune Signaling ◽  
Therapeutic Outcomes ◽  
Wide Range ◽  
Radiation Induced ◽  
Nuanced Understanding ◽  
The Impact

Radiotherapy is a major modality used to combat a wide range of cancers. Classical radiobiology principles categorize ionizing radiation (IR) as a direct cytocidal therapeutic agent against cancer; however, there is an emerging appreciation for additional antitumor immune responses generated by this modality. A more nuanced understanding of the immunological pathways induced by radiation could inform optimal therapeutic combinations to harness radiation-induced antitumor immunity and improve treatment outcomes of cancers refractory to current radiotherapy regimens. Here, we summarize how radiation-induced DNA damage leads to the activation of a cytosolic DNA sensing pathway mediated by cyclic GMP-AMP (cGAMP) synthase (cGAS) and stimulator of interferon genes (STING). The activation of cGAS–STING initiates innate immune signaling that facilitates adaptive immune responses to destroy cancer. In this way, cGAS–STING signaling bridges the DNA damaging capacity of IR with the activation of CD8+ cytotoxic T cell-mediated destruction of cancer—highlighting a molecular pathway radiotherapy can exploit to induce antitumor immune responses. In the context of radiotherapy, we further report on factors that enhance or inhibit cGAS–STING signaling, deleterious effects associated with cGAS–STING activation, and promising therapeutic candidates being investigated in combination with IR to bolster immune activation through engaging STING-signaling. A clearer understanding of how IR activates cGAS–STING signaling will inform immune-based treatment strategies to maximize the antitumor efficacy of radiotherapy, improving therapeutic outcomes.

scholarly journals CD85k Contributes to Regulatory T Cell Function in Chronic Viral Infections

2020 ◽  
Vol 22 (1) ◽  
pp. 31
Author(s):  
Anna Estrada Brull ◽  
Felix Rost ◽  
Josua Oderbolz ◽  
Florian R. Kirchner ◽  
Salomé Leibundgut-Landmann ◽  
...  
Keyword(s):  
T Cells ◽  
Immune Responses ◽  
Viral Infections ◽  
Current Knowledge ◽  
Murine Cytomegalovirus ◽  
Acute Type ◽  
Dependent Manner ◽  
Persistent Viral Infections ◽  
Lcmv Infection

Regulatory T cells (Tregs) prevent excessive immune responses and limit immune pathology upon infections. To fulfill this role in different immune environments elicited by different types of pathogens, Tregs undergo functional specialization into distinct subsets. During acute type 1 immune responses, type 1 Tregs are induced and recruited to the site of ongoing Th1 responses to efficiently control Th1 responses. However, whether a similar specialization process also takes place following chronic infections is still unknown. In this study, we investigated Treg specialization in persistent viral infections using lymphocytic choriomeningitis virus (LCMV) and murine cytomegalovirus (MCMV) infection as models for chronic and latent infections, respectively. We identify CD85k as a Th1-specific co-inhibitory receptor with sustained expression in persistent viral infections and show that recombinant CD85k inhibits LCMV-specific effector T cells. Furthermore, expression of the CD85k ligand ALCAM is induced on LCMV-specific and exhausted T cells during chronic LCMV infection. Finally, we demonstrate that type 1 Tregs arising during chronic LCMV infection suppress Th1 effector cells in an ALCAM-dependent manner. These results extend the current knowledge of Treg specialization from acute to persistent viral infections and reveal an important functional role of CD85k in Treg-mediated suppression of type 1 immunity.

scholarly journals In-host Modelling of COVID-19 in Humans

2020 ◽  
Author(s):  
Esteban A. Hernandez-Vargas ◽  
Jorge X. Velasco-Hernandez
Keyword(s):  
Immune Responses ◽  
Target Cell ◽  
Viral Infections ◽  
Cell Model ◽  
Influenza Infection ◽  
Severe Disease ◽  
Reproductive Number ◽  
Infected Cells ◽  
Eclipse Phase ◽  
The Impact

ABSTRACTCOVID-19 pandemic has underlined the impact of emergent pathogens as a major threat for human health. The development of quantitative approaches to advance comprehension of the current outbreak is urgently needed to tackle this severe disease. In this work, several mathematical models are proposed to represent SARS-CoV-2 dynamics in infected patients. Considering different starting times of infection, parameters sets that represent infectivity of SARS-CoV-2 are computed and compared with other viral infections that can also cause pandemics.Based on the target cell model, SARS-CoV-2 infecting time between susceptible cells (mean of 30 days approximately) is much slower than those reported for Ebola (about 3 times slower) and influenza (60 times slower). The within-host reproductive number for SARS-CoV-2 is consistent to the values of influenza infection (1.7-5.35). The best model to fit the data was including immune responses, which suggest a slow cell response peaking between 5 to 10 days post onset of symptoms. The model with eclipse phase, time in a latent phase before becoming productively infected cells, was not supported. Interestingly, both, the target cell model and the model with immune responses, predict that virus may replicate very slowly in the first days after infection, and it could be below detection levels during the first 4 days post infection. A quantitative comprehension of SARS-CoV-2 dynamics and the estimation of standard parameters of viral infections is the key contribution of this pioneering work.

scholarly journals Antibiotics Against COVID-19 and Mitochondria? Urgent Thinking Out of the Box

2020 ◽  
Author(s):  
Jaroslaw Tyszka ◽  
Karolina Kobos ◽  
Aleksandra Tyszka
Keyword(s):  
Immune System ◽  
Immune Responses ◽  
Viral Infections ◽  
Treatment Strategies ◽  
Local Health ◽  
Antiviral Immune Response ◽  
Health Authorities ◽  
Treatment Data ◽  
The Moment ◽  
The Impact

Italian, Spanish, French vs German, Austrian or Norwegian COVID-19 tracks? Antibiotics might have a partial impact on COVID-19 death rates in various countries. Our working hypotheses based on recent publications is that that antibiotics may be a major factor that negatively affects patients’ immune system during viral infections. We are all aware that there is no specific and effective medical treatment for COVID-19 so far. However, we know that our immune system is the only efficient weapon that fights against this syndrome right now. In fact, antibiotics are very often prescribed to prevent secondary infections following an antiviral immune response. Various antibiotic therapies have also been commonly applied to support COVID-19 treatments in China and Italy. Unfortunately, the frequent antibiotic off-site targets include mitochondria that are genetically and evolutionary closely linked to bacteria. Mitochondria are multifunctional organelles responsible for bioenergetics in nearly all our cells, acting as signaling hubs in antiviral and antibacterial immune responses. Several studies have demonstrated that mitochondria are vulnerable to antibacterial treatments, interrupting their physiology. Inhibition of these processes by antibiotics might render the immune system less capable of fighting acute COVID-19 viral infections. Some antibiotics, including those prescribed for COVID-19 in Wuhan, have been shown to inhibit the synthesis of mitochondrial DNA. The question is whether antibiotics support such a treatment or weaken patient immune responses in this case. This hypothesis should be evaluated based on comparative clinical data that seem to be unavailable at the moment. Possibly the COVID-19 risk group should be extended to all patients being treated with antibiotics, including those who finished antibiotic therapies days up to several months before SARS-CoV-2 infection. We therefore urge health service response groups to evaluate the impact of antibiotics on COVID-19 recovery vs death retrospective data. We would like to motivate international, national and local health authorities to share available clinical treatment data, discuss and optimize treatment strategies.

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