ABSTRACT
The COVID-19 pandemic has altered people's lifestyles around the world. Prevention of recurrent episodes of the disease and mitigation of its consequences are especially associated with effective post-COVID-19 rehabilitation in patients. The aim of the study was to evaluate the effects of the drug Likopid (glucosaminylmuramyl dipeptide, GMDP) for post-COVID-19 rehabilitation in patients. Material and methods. Patients who recovered from mild to moderate COVID-19 (n=60, mean age 54+/- 11.7 years) were randomized into the observation group (n=30, 15 men and 15 women) who received 2 courses of Licopid (1 mg twice a day) and the comparison group (n=30, 15 men and 15 women). Analysis of the phenotypic and functional characteristics of the innate immune cellular factors was carried out before the start of immunomodulatory therapy, immediately after the end of the course, and also after 6 months observations. In order to assess the quality of life of all patients, we used the SF-36 Health Status Survey and the Hospital Anxiety and Depression Scale questionnaires. Results. During assessing the effect of immunomodulatory therapy on the parameters of innate immunity of patients at the stage of rehabilitation after COVID-19, an increase in the protective cytolytic activity of CD16+ and CD8+Gr+ cells, as well as a persistent increase in TLR2, TLR4 and TLR9 expression was found, which indicates the antigen recognition recovery and presentation at the level of the monocytic link of the immune system. The use of GMDP as an immunomodulatory agent resulted in an 8-fold reduction in the frequency and severity of respiratory infections due to an increase in the total monocyte count. As a result of assessing patients' quality of life against the background of the therapy, a positive dynamic in role functioning was revealed in patients. In the general assessment of their health status, an increase in physical and mental well-being was noted during 6 months of observation. The comparison group showed no improvement in the psychoemotional state. Discussion. The study demonstrated the effectiveness of GMDP immunomodulatory therapy in correcting immunological parameters for post-COVID-19 rehabilitation in patients. The data obtained are consistent with the previously discovered ability of GMDP to restore impaired functions of phagocytic cells and induce the expression of their surface activation markers, which in turn contributes to an adequate response to pathogens. Conclusion. The study revealed that the correction of immunological parameters with the use of GMDP in COVID-19 convalescents contributed not only to a decrease in the frequency and severity of respiratory infections, but also to an improvement in the psycho-emotional state of patients, and a decrease in anxiety and depression.Copyright © Eco-Vector, 2023. All rights reserved.
ABSTRACT
The COVID-19 pandemic has altered people's lifestyles around the world. Prevention of recurrent episodes of the disease and mitigation of its consequences are especially associated with effective post-COVID-19 rehabilitation in patients. The aim of the study was to evaluate the effects of the drug Likopid (glucosaminylmuramyl dipeptide, GMDP) for post-COVID-19 rehabilitation in patients. Material and methods. Patients who recovered from mild to moderate COVID-19 (n=60, mean age 54+/- 11.7 years) were randomized into the observation group (n=30, 15 men and 15 women) who received 2 courses of Licopid (1 mg twice a day) and the comparison group (n=30, 15 men and 15 women). Analysis of the phenotypic and functional characteristics of the innate immune cellular factors was carried out before the start of immunomodulatory therapy, immediately after the end of the course, and also after 6 months observations. In order to assess the quality of life of all patients, we used the SF-36 Health Status Survey and the Hospital Anxiety and Depression Scale questionnaires. Results. During assessing the effect of immunomodulatory therapy on the parameters of innate immunity of patients at the stage of rehabilitation after COVID-19, an increase in the protective cytolytic activity of CD16+ and CD8+Gr+ cells, as well as a persistent increase in TLR2, TLR4 and TLR9 expression was found, which indicates the antigen recognition recovery and presentation at the level of the monocytic link of the immune system. The use of GMDP as an immunomodulatory agent resulted in an 8-fold reduction in the frequency and severity of respiratory infections due to an increase in the total monocyte count. As a result of assessing patients' quality of life against the background of the therapy, a positive dynamic in role functioning was revealed in patients. In the general assessment of their health status, an increase in physical and mental well-being was noted during 6 months of observation. The comparison group showed no improvement in the psychoemotional state. Discussion. The study demonstrated the effectiveness of GMDP immunomodulatory therapy in correcting immunological parameters for post-COVID-19 rehabilitation in patients. The data obtained are consistent with the previously discovered ability of GMDP to restore impaired functions of phagocytic cells and induce the expression of their surface activation markers, which in turn contributes to an adequate response to pathogens. Conclusion. The study revealed that the correction of immunological parameters with the use of GMDP in COVID-19 convalescents contributed not only to a decrease in the frequency and severity of respiratory infections, but also to an improvement in the psycho-emotional state of patients, and a decrease in anxiety and depression.Copyright © Eco-Vector, 2023. All rights reserved.
ABSTRACT
Outbreaks of chilblains, a hallmark sign of type I interferonopathies, have been reported during the COVID-19 pandemic. These cases occurred mostly in patients who were asymptomatic and showed negative results from PCR and serology tests for SARS-CoV-2. We hypothesized that chilblain patients are predisposed to mount a robust innate immunity against the virus, which clinically manifests as chilblains and promotes early viral clearance, thereby preventing pulmonary disease and precluding adaptive responses. By profiling skin lesions in the early stage following chilblain onset, we uncover a transient IRF7-dependent type I interferon (IFN) signature that is driven by the acral infiltration of systemically activated plasmacytoid dendritic cells (pDCs). Patients' peripheral blood mononuclear cells (PBMCs) demonstrate increased production of IFNalpha when exposed to SARS-CoV-2 and influenza A, but not herpes simplex virus 1 (HSV-1), indicating a heightened ability to detect RNA -but not DNA- viruses. Further investigations revealed enhanced responsiveness of pDCs in chilblain patients to the RNA sensor TLR7, but not the DNA sensor TLR9. Collectively, our study establishes a two-step model for the immunopathology of SARS-CoV-2-related chilblains: enhanced TLR7 immunity in pDCs, likely triggered by SARS-CoV-2 exposure at the mucosal site, leads to prompt viral clearance, which explains the lack of infection markers in most cases. Subsequently, systemic spread of activated pDCs and infiltration of the toes in response to mechanical stress or acral coldness, may result in IFN-mediated tissue damage with development of chilblains.Copyright © 2023
ABSTRACT
Background: Effective rehabilitation of patients who have had a SARS CoV-2 infection is essential to prevent re-infections and will improve the quality of life of people and reduce the burden on the healthcare system. Muramylpeptides are used in the prevention of seasonal diseases in children and adults in order to correct immunodeficiency states and prevent infectious complications. The aim of this study was to study the dynamic changes in the state of cellular factors of innate immunity and the levels of anxiety and depression in patients treated with glucosaminyl muramyl dipeptide (GMDP). Method(s): Patients who underwent mild to moderate COVID-19 (N = 60, mean age 54 +/- 11.7 years) were randomized to the study group (30 people, 15 men and 15 women) who received 2 courses of licopid 1 mg twice per day and a comparison group (30 people, 15 men and 15 women). Analysis of the phenotypic and functional characteristics of the cellular factors of the innate immune response was carried out before the start of immunomodulatory therapy, immediately after the end of the course, and also after 6 months. observations. To assess the quality of life of all patients, the SF-36 Health Status Survey and HADS questionnaires were used before the use of licopid, at the end of the course and after 6 months of follow-up. Result(s): In the course of assessing the effect of immunomodulatory therapy on the parameters of innate immunity of patients at the stage of rehabilitation after suffering COVID-19, an increase in the protective cytolytic activity of CD16+, CD8+Gr+ cells, as well as a persistent increase in the expression of TLR2, TLR4 and TLR9 was found, which indicates the restoration of antigenic recognition and presentations at the level of the monocytic link of the immune system. The use of GMDP as an immunomodulatory agent resulted in an 8-fold decrease in the frequency and severity of respiratory infections due to an increase in the total monocyte count, which persisted for 6 months from the start of therapy, while the use of systemic antibiotic therapy was not required, while in the comparison group -7 people were forced to resort to this therapy due to the severity of acute respiratory infections. When analyzing the assessment of the quality of life of patients against the background of the therapy, patients showed positive dynamics in role functioning, general assessment of their health status, and an increase in physical and mental well-being during 6 months of observation. In the comparison group, there was no improvement in the psycho-emotional state of patients. Conclusion(s): In this study, for the first time, it was found that the correction of immunological parameters when exposed to GMDP after a previous illness contributed not only to a decrease in the frequency and severity of respiratory infections, but also to an improvement in the psycho-emotional state of patients, and a decrease in anxiety and depression.
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Introduction: ACE-receptors are profusely expressed in the renal cell, making it highly susceptible for severe acute respiratory syndrome corona virus-2 (SARS-CoV-2) infection. After entering the cells, the virus induces high levels of cytokines, chemokines, and inflammatory responses, resulting neutrophilic infiltration, activation, and profuse reactive oxygen species (ROS) formation, leading to cellular necrosis and acute tubular injury. Proximal convoluted tube cell are rich in mitochondria and susceptible for developing acute kidney injury (AKI) due to mitochondrial stress. Early detection of AKI may helpful in its management, limiting the severity, avoiding nephrotoxic medicines and modifying the drug dose depending on renal function. Therefore, in the current study, we have determined the utility of urinary mitochondrial DNA (umt-DNA) and neutrophil gelatinase-associated lipocalin (NGAL) in predicting COVID-19-associated acute kidney injury (AKI) and mitochondrial stress and demonstrated the inflammatory response of urinary mt-DNA. Method(s): Live-related RTRs(n=66), who acquired SARS-CoV-2 infection and were admitted to a COVID hospital were included and subclassified into AKI (N=19) with > 25% spike in serum creatinine level from the pre-COVID-19 serum creatinine level, and non-AKI (N=47) whose serum creatinine value remained stable similar to the baseline value, or a rise of < 25% of the baseline values of pre-COVID-19. A 50ml urine sample was collected and umt-DNA and N-GAL was determined by the RT-PCR and ELISA methods respectively. A 10ml blood sample from 10 healthy volunteers was also collected for PBMC isolation and inflammatory response demonstration. A 1x106 PBMC was stimulated for 24hrs. with 1microg/ml of urinary DNA or TLR9 agonist CpG oligodeoxynucleotide (5'-tcgtcgttttcggcgc:gcgccg-3') in duplicate. Unstimulated PBMCs served as control. The gene expression of IL-10, IL-6, MYD88 was analyzed by the RT-PCR and IL-6, IL-10 level in supernatants by the ELISA. Result(s): Both the urinary mitochondrial gene ND-1 and NGAL level was significantly higher in AKI group compared to non-AKI. The mean ND-1 gene Ct in AKI group was (19.44+/-2.58 a.u) compared to non-AKI (21.77+/-3.60;p=0.013). The normalized ND-1 gene Ct in AKI was (0.79+/-0.11 a.u) compared to non-AKI (0.89+0.14;P=0.007). The median urinary NGAL level in AKI group was (453.53;range, 320.22-725.02, 95% CI) ng/ml compared to non-AKI (212.78;range, 219.80-383.06, 95%CI;p=0.015). The median urine creatinine normalized uNGAL was 4.78 (0.58-70.39) ng/mg in AKI group compared to 11.26 ng/mg (0.41-329.71) in non-AKI group. The area under curve of ND-1 gene Ct was 0.725, normalized ND-1 Ct was 0.713 and uNGAL was 0.663 and normalized uNGAL was 0.667 for detecting the AKI and mitochondrial stress. The IL-10 gene expression was downregulated in umt-DNA treated PBMCs compared to control (-3.5+/-0.40vs1.02+/-0.02, p<0.001). IL-6 and Myd88 gene expression was upregulated. The culture supernatant IL-10 and IL-6 level in umt-DNA treatment PBMCs vs control was 10.65+/-2.02 vs 30.3+/-5.47, p=0.001;and 200.2+/-33.67 vs 47.6+/-12.83, p=0.001 pg/ml respectively. Conclusion(s): Urinary mt-DNA quantification can detect the Covid19 associated AKI and mitochondrial distress with higher sensitivity than uNGAL in RTRs. Urinary mt-DNA also induces a robust inflammatory response in PBMCs, which may exacerbate the Covid19 associated allograft injury. No conflict of interestCopyright © 2023
ABSTRACT
The role of steroid hormones against infectious diseases has been extensively studied. From immunomodulatory action to direct inhibition of microorganism growth, hormones D3 (VD3) and 17beta-estradiol (E2), and the genetic pathways modulated by them, are key targets for a better understanding pathogenesis of infectious respiratory diseases (IRD) such as tuberculosis (TB) and the coronavirus disease-19 (COVID-19). Currently, the world faces two major public health problems, the outbreak of COVID-19, accounting for more than 6 million so far, and TB, more than 1 million deaths per year. Both, although resulting from different pathogens, the Mtb and the SARS-CoV-2, respectively, are considered serious and epidemic. TB and COVID-19 present similar infection rates between men and women, however the number of complications and deaths resulting from the two infections is higher in men when compared to women in childbearing age, which may indicate a role of the sex hormone E2 in the context of these diseases. E2 and VD3 act upon key gene pathways as important immunomodulatory players and supporting molecules in IRDs. This review summarizes the main roles of these hormones (VD3 and E2) in modulating immune and inflammatory responses and their relationship with TB and COVID-19.Copyright © Sociedade Brasileira de Genetica.
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The ongoing COVID-19 outbreak have posed a significant threat to public health worldwide. Recently Toll-like receptor (TLR) has been proposed to be the drug target of SARS-CoV-2 treatment, the specificity and efficacy of such treatments remain unknown. In the present study we performed the investigation of repurposed drugs via a framework comprising of Search Tool for Interacting Chemicals (STITCH), Kyoto Encyclopedia of Genes and Genomes (KEGG), molecular docking, and virus-host-drug interactome mapping. Chloroquine (CQ) and hydroxychloroquine (HCQ) were utilized as probes to explore the interaction network that is linked to SARS-CoV-2. 47 drug targets were shown to be overlapped with SARS-CoV-2 network and were enriched in TLR signaling pathway. Molecular docking analysis and molecular dynamics simulation determined the direct binding affinity of TLR9 to CQ and HCQ. Furthermore, we established SARS-CoV-2-human-drug protein interaction map and identified the axis of TLR9-ERC1-Nsp13 and TLR9-RIPK1-Nsp12. Therefore, the elucidation of the interactions of SARS-CoV-2 with TLR9 axis will not only provide pivotal insights into SARS-CoV-2 infection and pathogenesis but also improve the treatment against COVID-19.
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BACKGROUND AND PURPOSE: Mitochondria play a central role in the host response to viral infection and immunity, being key to antiviral signaling and exacerbating inflammatory processes. Mitochondria and Toll-like receptor (TLR) have been suggested as potential targets in SARS-CoV-2 infection. However, the involvement of TLR9 in SARS-Cov-2-induced endothelial dysfunction and potential contribution to cardiovascular complications in COVID-19 have not been demonstrated. This study determined whether infection of endothelial cells by SARS-CoV-2 affects mitochondrial function and induces mitochondrial DNA (mtDNA) release. We also questioned whether TLR9 signaling mediates the inflammatory responses induced by SARS-CoV-2 in endothelial cells. EXPERIMENTAL APPROACH: Human umbilical vein endothelial cells (HUVECs) were infected by SARS-CoV-2 and immunofluorescence was used to confirm the infection. Mitochondrial function was analyzed by specific probes and mtDNA levels by real-time polymerase chain reaction (RT-PCR). Inflammatory markers were measured by ELISA, protein expression by western blot, intracellular calcium (Ca2+) by FLUOR-4, and vascular reactivity with a myography. KEY RESULTS: SARS-CoV-2 infected HUVECs, which express ACE2 and TMPRSS2 proteins, and promoted mitochondrial dysfunction, i.e. it increased mitochondria-derived superoxide anion, mitochondrial membrane potential, and mtDNA release, leading to activation of TLR9 and NF-kB, and release of cytokines. SARS-CoV-2 also decreased nitric oxide synthase (eNOS) expression and inhibited Ca2+ responses in endothelial cells. TLR9 blockade reduced SARS-CoV-2-induced IL-6 release and prevented decreased eNOS expression. mtDNA increased vascular reactivity to endothelin-1 (ET-1) in arteries from wild type, but not TLR9 knockout mice. These events were recapitulated in serum samples from COVID-19 patients, that exhibited increased levels of mtDNA compared to sex- and age-matched healthy subjects and patients with comorbidities. CONCLUSION AND APPLICATIONS: SARS-CoV-2 infection impairs mitochondrial function and activates TLR9 signaling in endothelial cells. TLR9 triggers inflammatory responses that lead to endothelial cell dysfunction, potentially contributing to the severity of symptoms in COVID-19. Targeting mitochondrial metabolic pathways may help to define novel therapeutic strategies for COVID-19.
Subject(s)
COVID-19 , DNA, Mitochondrial , Animals , DNA, Mitochondrial/genetics , DNA, Mitochondrial/metabolism , Endothelial Cells/metabolism , Humans , Mice , Mitochondria/metabolism , SARS-CoV-2 , Toll-Like Receptor 9/genetics , Toll-Like Receptor 9/metabolismABSTRACT
Background: Irritable bowel syndrome (IBS) is the most common functional gastrointestinal disorder characterized by abdominal pain and changes in intestinal movements in the absence of structural or biochemical abnormalities. In spite of the high prevalence its etiology is unknown and there are no specific diagnostic laboratory tests. Material and Methods: In a case/control study, 36 biopsy samples taken from of irritable bowel syndrome patients and 30 biopsy samples as control were obtained. expression of TLR 3, TLR 9 and RIG 1 in Macrophages, Lymphocytes and Plasma cells in terms of percentage and color intensity were evaluated by Immunohistochemistry. The obtained data were statistically analyzed using Mann Whitney u, chi-square methods.
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Rationale: The SARS-CoV-2 pandemic has underscored the need for novel anti-infectious strategies, including host-directed therapeutics, against existing and emerging respiratory pathogens. We have reported that an aerosolized therapeutic comprised of a Toll-like receptor (TLR)-2/6 agonist, Pam2CSK4, and a TLR-9 agonist, ODN M362, stimulate pathogen-agnostic innate immune responses in lung epithelial cells. This therapeutic (“Pam2-ODN”) promotes synergistic microbicidal activity and host survival benefit against pneumonia caused by a wide range of pathogens. Here, we study the immunomodulatory signaling mechanisms required to effect this inducible epithelial resistance. Methods: Bioinformatic analysis of transcriptional responses from human and mouse lung epithelium al cells to influenza A H1N1 or SARS-CoV-2 (GSE147507) or Pam2-ODN (GSE289984, GSE26864) were analyzed using R and IPA software to identify essential transcription factors (TFs). Lung cell population dynamics were studied for TFs related to Pam2-ODN immunomodulatory signaling using high-throughput imaging flow cytometry (IFC). Human or mouse lung epithelial cells were stimulated with PBS or Pam2-ODN and single or dual inhibitors of TFs before challeng with influenza A H3N2 (IAV) or coronavirus OC43 (CoV) to compare the epithelium-specific transcriptional control of relevant TFs using in-cell western blotting, IFC and hemagglutination for viral burdens. Results: Functional enrichment analysis revealed RelA and cJUN to be major immunomodulatory TFs of Pam2-ODN and activators of leukocyte- and epithelial-derived antiviral immune mechanisms targeting replication of influenza A and SARS-CoV-2. Cell population dynamics studied from mouse lungs confirmed activation of RelA and cJUN in CD45+, EpCAM- leukocytes and in CD45-, EpCAM+ epithelial cells, with predominant activation of the lung epithelium and none or minimal activation of structural cell populations such as fibroblasts or endothelial cells. Studies of epithelium-specific signaling in vitro revealed co-activation of RelA-(pS536) and cJun- (pS73) TFs with Pam2-ODN, and earlier onset of cJUN phosphorylation and nuclear translocation with Pam2-ODN after IAV or CoV infection. Individual or dual inhibition of RelA and/or cJUN activity in vitro disrupted the antiviral activity of Pam2-ODN of IAV infected cells. Conclusion: Pam2-ODN induces unique, pathogen-agnostic protective signaling in lung epithelial cells that involves cooperative activation of RelA and cJUN. This combined TF signaling mechanism is not observed in other structural lung cell populations after Pam2-ODN exposure. Further, the phospho-regulation dynamics of RelA and cJUN are not replicated by IAV or CoV infection alone, suggesting a novel therapeutic process that can be leveraged to protect individuals against pneumonia. (Figure Presented).
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Objective: To describe, to the best of our knowledge, the first case of myelin oligodendrocyte glycoprotein (MOG) antibody syndrome associated with the Moderna COVID-19 mRNA vaccine, and a case of acute transverse myelitis (ATM) associated with the Pfizer COVID-19 mRNA vaccine. Background: Post-vaccination CNS demyelinating syndromes have been reported with different vaccines, most notably the influenza and human papilloma vaccines. Two cases of new-onset multiple sclerosis (MS) and a case of new-onset neuromyelitis optica (NMO) associated with the Pfizer vaccine have been reported. One case of new-onset relapsing-remitting MS was reported after the Moderna vaccine. Design/Methods: NA Results: A 38-year-old man developed left blurry vision, lower extremity weakness/paresthesia and bowel/bladder dysfunction three days after receiving the Moderna vaccine. He was diagnosed with left optic neuritis and longitudinally extensive transverse myelitis;he tested positive for MOG antibody. A 39-year-old woman presented with progressive lower extremity weakness/numbness seven days after receiving the Pfizer vaccine. She was diagnosed with ATM. Both patients improved with intravenous corticosteroids. Conclusions: The association between CNS demyelinating syndromes and vaccination has been reported for many years. The proposed pathogenesis of CNS demyelinating syndromes after vaccines includes molecular mimicry, epitope spreading, bystander activation, polyclonal activation, effects of adjuvants, and depends on vaccine-related factors like type, dose, and route of administration. The adjuvanticity of COVID-19 vaccines is novel in that it involves Toll-like Receptor (TLR) 7 and 9 agonism, and several immune-mediated disorders have been linked to altered nucleic acid metabolism and processing that have stimulated TLR-7 and TLR-9 experimentally. While the risk of CNS demyelinating events is non-negligible, the incidence is very low. The rate of demyelinating events after the COVID-19 infection is higher. Therefore, we feel that the overall benefits of vaccination outweigh the marginal risk. However, providers should be aware of this potential neurological complication of the COVID-19 mRNA vaccines.
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Background: The number of cases of SARS-CoV-2 infection after BNT162b2 mRNA vaccination is significantly higher in elderly people, which has been associated to lower frequencies of SARS-CoV-2 neutralizing antibodies. Our objective was to investigate the differences in the cellular response in old and young people after the SARS-CoV-2 vaccination. Methods: Young (24-53 years, n=20) and old (70-76 years, n=20) healthy subjects vaccinated with BNT162b2 SARS-CoV-2 mRNA vaccine were studied before vaccination, two weeks after the first dose and two months after the second dose. SARS-CoV-2 (spike) specific T cell response, TLR-4 dependent monocyte response and TLR-3 dependent myeloid dendritic cell (DC) response and DC, monocyte and T-cell immunophenotype, were studied by multiparametric flow cytometry. TLR-9 dependent interferon-α (IFNα) production by PBMCs was measured by ELISA and thymic function assayed by sj/β TREC ratio using droplet digital PCR. Results: The SARS-CoV-2 specific T cell response was lower and less polyfunctional in old people. Most of the differences in CD4+ and CD8+ T cell subsets were found in degranulation (CD107a), cytokine (IFN-γ) and cytotoxic (perforin) profile (eg, Memory CD8+ perforin+;p=0.0016). The lower SARS-CoV-2 specific T cell response was associated with lower thymic function levels (eg, Memory CD4+ perforin+, r=0.631;p=0.0001). The vaccination induced a higher activation and proliferation (eg, CM CD4 HLA-DR+ p=0.002, Ki67+ p=0.019) of T cells in young people than in old ones, in addition to a higher level of homing makers to different tissues and inflammatory sites (eg, CD1c mDC integrin β7+ p=0.001, intermediate monocytes CCR2+ p=0.0003) in DCs and monocytes. Moreover, after the vaccination, old subjects showed a higher production of proinflammatory cytokines by monocytes in response to LPS (eg, IL6+;p=0.015), while young people showed a higher production of IFNα by plasmacytoid DCs after CpG-A stimulation (p=0.0009). Conclusion: The magnitude and polyfunctionality of SARS-CoV-2 specific T cell response is lower in old people, associated to a lower thymic function. In old people, the vaccination induced less immune activation and homing and the myeloid TLR-dependent response is directed towards a proinflammatory response, while in young people prevails IFNα production, related to a more effective antiviral response. These results support the additional boosting strategies in this vulnerable population.
ABSTRACT
SARS-CoV-2 is a coronavirus that infects epithelial cells in the naso- and oropharynx before infecting epithelial cells of the lower airways and alveoli and in severe COVID-19 spreading systemically and inducing a systemic inflammatory response. SARS-CoV-2 is spread mainly by virus particles in droplets and aerosols. This suggests that inhaled therapies may be useful in the treatment of early COVID-19 disease before severe respiratory systemic features develop and potentially in reducing transmission of the virus in the community. To be effective any inhaled therapy must be rapidly acting to prevent viral replication in respiratory epithelial cells to prevent the disease spreading down the respiratory tract and into the systemic circulation. It also needs to be safe and available for early prescription in order to prevent severe disease and hospitalisation. The development of inhaled therapies for COVID-19 may involved repurposing of existing inhaled therapies or developing inhaled formulations of new drugs with antiviral effects. Patients with asthma and COPD were reported to be less likely to be hospitalised with SARS-CoV-2 infection despite the concern that this coronavirus would have severe consequences for these patients as coronaviruses are known to trigger severe exacerbations. One possibility was that this may be due to the widespread treatment with inhaled corticosteroids (ICS), which are known to suppress ACE2 and TMPRSS2 on epithelial cells that are key entry receptors for the virus and also reduce virus replication in vitro. A community based open label parallel group phase 2 study of the ICS budesonide (800 lg bid until recovery) in people with early symptoms (within 7 days of onset) of COVID-19 and confirmed by PCR testing (STOIC) showed that only 1/69 people in the ICS group developed severe disease compared with 10/70 in the usual care group.1 Clinical recovery was also shorter in the ICS group. This finding was confirmed in an open label study of inhaled budesonide in individuals over the age of 65 years at risk from severe COVID-19 (PRINCIPLE), which showed a reduction in time to recovery and a trend towards reduced hospitalisation and death.2 Several other trials, including double-blind studies, of ICS in early COVID-19 are currently underway with different corticosteroids, including ciclesonide, which appears to be the most effective against SARS-CoV-2 in vitro.3 However, a recent double-blind study of nasal and inhaled ciclesonide failed to show any benefit in early COVID-19, although the population was mainly young adults who have a low risk of disease progression.4 The mechanism of action of ICS in COVID- 19 has not yet been established, but may involve reduced viral entry due to suppression of ACE2 and TMPRSS2 in airway epithelial cells, reduced viral proliferation or reduced inflammatory mediators secreted by airway epithelial cells that may promote viral spreading. Interferon b1 is currently approve for treating multiple sclerosis. Nebulised IFN-b1a (SNG001) gave a greater degree of clinical improvement in hospitalised COVID-19 patients and a reduction on symptoms (mainly dyspnoea) compared to with placebo and was well tolerated.5 However, studies in early disease are underway but have not yet been reported, although there are logistical problems in the need for a nebuliser to deliver the drug. Inhaled PUL-42 is a combination of a TLR2/6 and a TLR9 inhibitors which is effective in a single inhaled dose against SARS-CoV and MERS-CoV infection in mice and reduces the lung viral load.6 This drug is now in clinical trials for COVID-19. Other inhaled drugs, including antivirals such as remdesivir and niclosamide, are also in development.
ABSTRACT
By mapping the clinical pathophysiology of the novel coronavirus disease 2019 (COVID-19) against insights from virology, immunology, genomics, epidemiology and pharmacology, it is here proposed that the pathogen recognition receptor called toll like receptor 9 (TLR9) might have a pivotal role in the pathogenesis of COVID-19. Severe Acute Respiratory Syndrome Coronavirus 2, is causing the greatest global social and economic disruption since world war II. Lack of a vaccine, lack of successful treatment and limitations of the healthcare workforce and resources needed to safeguard patients with severe COVID-19 on the edge of life, demands radical preventive measures. It is urgently needed to identify biomarkers and drug candidates so that vulnerable individuals can be recognized early and severe multi-organ complications can be prevented or dampened. The TLR9 COVID-19 hypothesis describes a mechanism of action that could explain a wide spectrum of manifestations observed in patients with severe COVID-19. The introduced hypothesis proposes biomarkers for identification of vulnerable individuals and positions TLR9 as a promising multifaceted intervention target for prevention and/or treatment of COVID-19. TLR9 agonists might have value as prophylactic vaccine adjuvants and therapeutic immune stimulators at the early onset of disease. Additionally, in this current manuscript it is proposed for the first time that TLR9 could be considered as a target of "inhibition" aimed to dampen hyperinflammation and thrombotic complications in vulnerable patients that are at risk of developing late stages of COVID-19. The readily availability of TLR9 modulating drug candidates that have reached clinical testing for other disorders could favor a fast track development scenario, an important advantage under the current high unmet medical need circumstances regarding COVID-19.