Innate Immunity In Protection Research Articles

Innate Immunity in Protection and Pathogenesis During Coronavirus Infections and COVID-19.

The COVID-19 pandemic was caused by the recently emerged β-coronavirus SARS-CoV-2. SARS-CoV-2 has had a catastrophic impact, resulting in nearly 7 million fatalities worldwide to date. The innate immune system is the first line of defense against infections, including the detection and response to SARS-CoV-2. Here, we discuss the innate immune mechanisms that sense coronaviruses, with a focus on SARS-CoV-2 infection and how these protective responses can become detrimental in severe cases of COVID-19, contributing to cytokine storm, inflammation, long-COVID, and other complications. We also highlight the complex cross talk among cytokines and the cellular components of the innate immune system, which can aid in viral clearance but also contribute to inflammatory cell death, cytokine storm, and organ damage in severe COVID-19 pathogenesis. Furthermore, we discuss how SARS-CoV-2 evades key protective innate immune mechanisms to enhance its virulence and pathogenicity, as well as how innate immunity can be therapeutically targeted as part of the vaccination and treatment strategy. Overall, we highlight how a comprehensive understanding of innate immune mechanisms has been crucial in the fight against SARS-CoV-2 infections and the development of novel host-directed immunotherapeutic strategies for various diseases.

Onchocerca volvulus bivalent subunit vaccine induces protective immunity in genetically diverse collaborative cross recombinant inbred intercross mice

This study tests the hypothesis that an Onchocerca volvulus vaccine, consisting of two recombinant antigens (Ov-103 and Ov-RAL-2) formulated with the combination-adjuvant Advax-2, can induce protective immunity in genetically diverse Collaborative Cross recombinant inbred intercross mice (CC-RIX). CC-RIX lines were immunized with the O. volvulus vaccine and challenged with third-stage larvae. Equal and significant reductions in parasite survival were observed in 7 of 8 CC-RIX lines. Innate protective immunity was seen in the single CC-RIX line that did not demonstrate protective adaptive immunity. Analysis of a wide array of immune factors showed that each line of mice have a unique set of immune responses to vaccination and challenge suggesting that the vaccine is polyfunctional, inducing different equally-protective sets of immune responses based on the genetic background of the immunized host. Vaccine efficacy in genetically diverse mice suggests that it will also be effective in genetically complex human populations.

Interferon-Induced Transmembrane Proteins Mediate Viral Evasion in Acute and Chronic Hepatitis C Virus Infection.

Although adaptive immune responses against hepatitis C virus (HCV) infection have been studied in great detail, the role of innate immunity in protection against HCV infection and immune evasion is only partially understood. Interferon-induced transmembrane proteins (IFITMs) are innate effector proteins restricting host cell entry of many enveloped viruses, including HCV. However, the clinical impact of IFITMs on HCV immune escape remains to be determined. Here, we show that IFITMs promote viral escape from the neutralizing antibody (nAb) response in clinical cohorts of HCV-infected patients. Using pseudoparticles bearing HCV envelope proteins from acutely infected patients, we show that HCV variants isolated preseroconversion are more sensitive to the antiviral activity of IFITMs than variants from patients isolated during chronic infection postseroconversion. Furthermore, HCV variants escaping nAb responses during liver transplantation exhibited a significantly higher resistance to IFITMs than variants that were eliminated posttransplantation. Gain-of-function and mechanistic studies revealed that IFITMs markedly enhance the antiviral activity of nAbs and suggest a cooperative effect of human monoclonal antibodies and IFITMs for antibody-mediated neutralization driving the selection pressure in viral evasion. Perturbation studies with the IFITM antagonist amphotericin B revealed that modulation of membrane properties by IFITM proteins is responsible for the IFITM-mediated blockade of viral entry and enhancement of antibody-mediated neutralization. Conclusion: Our results indicate IFITM proteins as drivers of viral immune escape and antibody-mediated HCV neutralization in acute and chronic HCV infection. These findings are of clinical relevance for the design of urgently needed HCV B-cell vaccines and might help to increase the efficacy of future vaccine candidates.

A novel mechanism linking memory stem cells with innate immunity in protection against HIV-1 infection

HIV infection affects 37 million people and about 1.7 million are infected annually. Among the phase III clinical trials only the RV144 vaccine trial elicited significant protection against HIV-1 acquisition, but the efficacy and immune memory were inadequate. To boost these vaccine functions we studied T stem cell memory (TSCM) and innate immunity. TSCM cells were identified by phenotypic markers of CD4+ T cells and they were further characterised into 4 subsets. These expressed the common IL-2/IL-15 receptors and another subset of APOBEC3G anti-viral restriction factors, both of which were upregulated. In contrast, CD4+ TSCM cells expressing CCR5 co-receptors and α4β7 mucosal homing integrins were decreased. A parallel increase in CD4+ T cells was recorded with IL-15 receptors, APOBEC3G and CC chemokines, the latter downmodulating CCR5 molecules. We suggest a novel mechanism of dual memory stem cells; the established sequential memory pathway, TSCM →Central →Effector memory CD4+ T cells and the innate pathway consisting of the 4 subsets of TSCM. Both pathways are likely to be activated by endogenous HSP70. The TSCM memory stem cell and innate immunity pathways have to be optimised to boost the efficacy and immune memory of protection against HIV-1 in the clinical trial.

The emerging role of innate immunity in protection against HIV-1 infection

Preventive immunization against HIV-1 infection requires a rapid immune response that does not rely exclusively on B or T cell memory. Innate immunity may fulfill this function as it may be activated directly at the time of HIV-1 transmission, inhibit early HIV-1 replication, stimulate adaptive immunity and enable specific antibodies followed by CD8(+) T cells to deal with the virus effectively. The three components of innate immunity - cellular, extracellular and intracellular - are presented, with an example given for each of these components; gammadelta T cells, CC chemokines and APOBEC3G. This brief account is presented to highlight the immuno-virological concept of coordinating activated innate immunity with adaptive antibody and T cell responses in preventive vaccination against HIV-1 infection.

Immunidad innata y nuevos adyuvantes

Vaccination remains the most cost-effective biomedical approach to the control of infectious diseases in livestock. Vaccines based on killed pathogens or subunit antigens are safer but are often ineffective and require coadministration with adjuvants to achieve efficacy. Unfortunately, most conventional adjuvants are poorly defined, complex substances that fail to meet the stringent criteria for safety and efficacy desired in new generation vaccines. A new generation of adjuvants that work by activating innate immunity presents exciting opportunities to develop safer, more potent vaccines. In this review the authors highlight the role of innate immunity in protection against infectious disease and provide some examples of promising new adjuvants that activate innate immunity. They do not review the conventional adjuvants present in many vaccines since they have been reviewed extensively previously.

Adhesion molecule deficiencies increase Porphyromonas gingivalis-induced alveolar bone loss in mice.

Alveolar bone resorption can be induced in specific-pathogen-free mice by oral infection with Porphyromonas gingivalis (P. J. Baker, R. T. Evans, and D. C. Roopenian, Arch. Oral Biol. 39:1035-1040, 1994). Here we used a mouse strain, C57BL/6J, which is relatively resistant to P. gingivalis-induced bone loss to examine whether partial or complete deletion of various adhesion molecules would increase susceptibility. Complete deletion of P-selectin or nearly complete lack of expression of intercellular adhesion molecule 1 (ICAM-1) led to increased susceptibility to bone resorption after oral infection, while a hypomorphic defect in beta(2)-integrins did not. Both the total amount of bone lost and the number of sites at which there was significant loss were increased in mice deficient in either ICAM-1 or P-selectin. Each of the three adhesion molecule deficiencies was sufficient to decrease P. gingivalis-specific serum immunoglobulin G responses, but lower antibody titers did not lead to increased bone loss in partially beta(2)-integrin-deficient mice. In conclusion, P-selectin and ICAM-1 deficiencies increase susceptibility to and severity of alveolar bone loss after P. gingivalis infection. This finding underscores the importance of innate immunity in protection against P. gingivalis-induced alveolar bone resorption.