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1.
J Immunol ; 211(2): 252-260, 2023 07 15.
Article in English | MEDLINE | ID: covidwho-20241408

ABSTRACT

SARS-CoV-2 has caused an estimated 7 million deaths worldwide to date. A secreted SARS-CoV-2 accessory protein, known as open reading frame 8 (ORF8), elicits inflammatory pulmonary cytokine responses and is associated with disease severity in COVID-19 patients. Recent reports proposed that ORF8 mediates downstream signals in macrophages and monocytes through the IL-17 receptor complex (IL-17RA, IL-17RC). However, generally IL-17 signals are found to be restricted to the nonhematopoietic compartment, thought to be due to rate-limiting expression of IL-17RC. Accordingly, we revisited the capacity of IL-17 and ORF8 to induce cytokine gene expression in mouse and human macrophages and monocytes. In SARS-CoV-2-infected human and mouse lungs, IL17RC mRNA was undetectable in monocyte/macrophage populations. In cultured mouse and human monocytes and macrophages, ORF8 but not IL-17 led to elevated expression of target cytokines. ORF8-induced signaling was fully preserved in the presence of anti-IL-17RA/RC neutralizing Abs and in Il17ra-/- cells. ORF8 signaling was also operative in Il1r1-/- bone marrow-derived macrophages. However, the TLR/IL-1R family adaptor MyD88, which is dispensable for IL-17R signaling, was required for ORF8 activity yet MyD88 is not required for IL-17 signaling. Thus, we conclude that ORF8 transduces inflammatory signaling in monocytes and macrophages via MyD88 independently of the IL-17R.


Subject(s)
COVID-19 , Monocytes , Humans , Mice , Animals , Monocytes/metabolism , SARS-CoV-2/genetics , Myeloid Differentiation Factor 88/genetics , Myeloid Differentiation Factor 88/metabolism , Receptors, Interleukin-17/genetics , Receptors, Interleukin-17/metabolism , Open Reading Frames , COVID-19/genetics , Macrophages/metabolism , Cytokines/metabolism
2.
Int Immunopharmacol ; 120: 110240, 2023 Jul.
Article in English | MEDLINE | ID: covidwho-2313874

ABSTRACT

Pneumonia is an acute inflammation of the lungs induced by pathogenic microorganisms, immune damage, physical and chemical factors, and other factors, and the latest outbreak of novel coronavirus pneumonia is also an acute lung injury (ALI) induced by viral infection. However, there are currently no effective treatments for inflammatory cytokine storms in patients with ALI/acute respiratory distress syndrome (ARDS). Protein kinase D (PKD) is a highly active kinase that has been shown to be associated with the production of inflammatory cytokines. Therefore, small-molecule compounds that inhibit PKD may be potential drugs for the treatment of ALI/ARDS. In the present study, we evaluated the ability of the small-molecule inhibitor CRT0066101 to attenuate lipopolysaccharide (LPS)-induced inflammatory cytokine production through in vitro cell experiments and a mouse pneumonia model. We found that CRT0066101 significantly reduced the protein and mRNA levels of LPS-induced cytokines (e.g., IL-6, TNF-α, and IL-1ß). CRT0066101 inhibited MyD88 and TLR4 expression and reduced NF-κB, ERK, and JNK phosphorylation. CRT0066101 also reduced NLRP3 activation, inhibited the assembly of the inflammasome complex, and attenuated inflammatory cell infiltration and lung tissue damage. Taken together, our data indicate that CRT0066101 exerts anti-inflammatory effects on LPS-induced inflammation through the TLR4/MyD88 signaling pathway, suggesting that CRT0066101 may have therapeutic value in acute lung injury and other MyD88-dependent inflammatory diseases.


Subject(s)
Acute Lung Injury , COVID-19 , Pneumonia , Respiratory Distress Syndrome , Mice , Animals , Cytokine Release Syndrome/metabolism , Myeloid Differentiation Factor 88/metabolism , Lipopolysaccharides/pharmacology , Toll-Like Receptor 4/metabolism , COVID-19/metabolism , Lung/pathology , Pneumonia/pathology , Acute Lung Injury/chemically induced , NF-kappa B/metabolism , Inflammation/metabolism , Cytokines/metabolism , Respiratory Distress Syndrome/metabolism
3.
Mediators Inflamm ; 2023: 2899271, 2023.
Article in English | MEDLINE | ID: covidwho-2298452

ABSTRACT

Toll-like receptors (TLRs) are the most studied receptors among the pattern recognition receptors (PRRs). They act as microbial sensors, playing major roles in the regulation of the innate immune system. TLRs mediate their cellular functions through the activation of MyD88-dependent or MyD88-independent signaling pathways. Myd88, or myeloid differentiation primary response 88, is a cytosolic adaptor protein essential for the induction of proinflammatory cytokines by all TLRs except TLR3. While the crucial role of Myd88 is well described, the contribution of other adaptors in mediating TLR signaling and function has been underestimated. In this review, we highlight important results demonstrating that TIRAP and TRAM adaptors are also required for full signaling activity and responses induced by most TLRs.


Subject(s)
Myeloid Differentiation Factor 88 , Toll-Like Receptor 4 , Toll-Like Receptor 3 , Toll-Like Receptors , Signal Transduction/physiology , Adaptor Proteins, Signal Transducing
4.
J Exp Med ; 220(5)2023 05 01.
Article in English | MEDLINE | ID: covidwho-2260121

ABSTRACT

X-linked recessive deficiency of TLR7, a MyD88- and IRAK-4-dependent endosomal ssRNA sensor, impairs SARS-CoV-2 recognition and type I IFN production in plasmacytoid dendritic cells (pDCs), thereby underlying hypoxemic COVID-19 pneumonia with high penetrance. We report 22 unvaccinated patients with autosomal recessive MyD88 or IRAK-4 deficiency infected with SARS-CoV-2 (mean age: 10.9 yr; 2 mo to 24 yr), originating from 17 kindreds from eight countries on three continents. 16 patients were hospitalized: six with moderate, four with severe, and six with critical pneumonia, one of whom died. The risk of hypoxemic pneumonia increased with age. The risk of invasive mechanical ventilation was also much greater than in age-matched controls from the general population (OR: 74.7, 95% CI: 26.8-207.8, P < 0.001). The patients' susceptibility to SARS-CoV-2 can be attributed to impaired TLR7-dependent type I IFN production by pDCs, which do not sense SARS-CoV-2 correctly. Patients with inherited MyD88 or IRAK-4 deficiency were long thought to be selectively vulnerable to pyogenic bacteria, but also have a high risk of hypoxemic COVID-19 pneumonia.


Subject(s)
COVID-19 , Myeloid Differentiation Factor 88 , Child , Humans , Adaptor Proteins, Signal Transducing , COVID-19/complications , Myeloid Differentiation Factor 88/genetics , SARS-CoV-2 , Toll-Like Receptor 7
5.
Arch Virol ; 168(3): 95, 2023 Feb 25.
Article in English | MEDLINE | ID: covidwho-2279451

ABSTRACT

Epigenetic modifications play a significant role in the host's immune response to viral infection. Two epigenetic events, DNA methylation and histone acetylation, are crucial for modifying the chromatin architecture and the location of regulatory elements such as promoters and enhancers. In this case-control study, we evaluated the expression of genes involved in epigenetic machinery (DNMT1, DNMT3A, DNMT3B, HDAC2, and HDAC3) and the degree of methylation of promoters of immune response genes (IFITM1/2/3, TLR3/4, TNF-α, NF-κB, and MYD88) as well as global methylation (LINE-1 and global 5-mC) in blood samples from 120 COVID-19 patients (30 mild, 30 moderate, 30 severe, and 30 critical) and 30 healthy subjects without COVID-19. In contrast to previous reports, DNMT3A and DNMT3B expression was found to be significantly downregulated in COVID-19 cases, whereas DNMT1, HDAC2, and HDAC3 expression did not change. DNMT1 and DNMT3A were negatively correlated with COVID-19 severity. Critically ill patients had lower HDAC3 expression levels. TLR4 and TNF-α had increased promoter methylation, whereas IFITM1/2/3, TLR3, NF-κB, MYD88, and LINE-1 did not differ between cases and controls. Methylation of the TNF-α promoter increased as disease severity increased. Significantly less methylation of the TLR3 promoter was observed in patients with a positive outcome (recovery). We also found a correlation between the expression of DNMT3B and the methylation level of the TLR4 promoter. In milder cases, the global 5-mC levels were lower than that in more severe cases. Our findings suggest the exclusion of DNMTs inhibitors previously recommended for COVID-19 treatment and the need for additional research in this area.


Subject(s)
COVID-19 , DNA Methylation , Humans , Tumor Necrosis Factor-alpha/genetics , Toll-Like Receptor 4/genetics , NF-kappa B/genetics , Case-Control Studies , COVID-19 Drug Treatment , Myeloid Differentiation Factor 88/genetics , Toll-Like Receptor 3/genetics , COVID-19/genetics , DNA (Cytosine-5-)-Methyltransferases/genetics , DNA (Cytosine-5-)-Methyltransferases/metabolism , DNA (Cytosine-5-)-Methyltransferase 1/genetics , DNA (Cytosine-5-)-Methyltransferase 1/metabolism , DNA/metabolism
6.
Dev Comp Immunol ; 140: 104626, 2023 03.
Article in English | MEDLINE | ID: covidwho-2236467

ABSTRACT

One of the most studied defense mechanisms against invading pathogens, including viruses, are Toll-like receptors (TLRs). Among them, TLR3, TLR7, TLR8 and TLR9 detect different forms of viral nucleic acids in endosomal compartments, whereas TLR2 and TLR4 recognize viral structural and nonstructural proteins outside the cell. Although many different TLRs have been shown to be involved in SARS-CoV-2 infection and detection of different structural proteins, most studies have been performed in vitro and the results obtained are rather contradictory. In this study, we report using the unique advantages of the zebrafish model for in vivo imaging and gene editing that the S1 domain of the Spike protein from the Wuhan strain (S1WT) induced hyperinflammation in zebrafish larvae via a Tlr2/Myd88 signaling pathway and independently of interleukin-1ß production. In addition, S1WT also triggered emergency myelopoiesis, but in this case through a Tlr2/Myd88-independent signaling pathway. These results shed light on the mechanisms involved in the fish host responses to viral proteins.


Subject(s)
COVID-19 , Spike Glycoprotein, Coronavirus , Toll-Like Receptor 2 , Animals , COVID-19/immunology , Myeloid Differentiation Factor 88/genetics , SARS-CoV-2 , Toll-Like Receptor 2/genetics , Zebrafish/genetics
7.
Brain Behav Immun ; 108: 204-220, 2023 02.
Article in English | MEDLINE | ID: covidwho-2149375

ABSTRACT

Increasing evidence supports the pathogenic role of neuroinflammation in psychiatric diseases, including major depressive disorder (MDD) and neuropsychiatric symptoms of Coronavirus disease 2019 (COVID-19); however, the precise mechanism and therapeutic strategy are poorly understood. Here, we report that myeloid differentiation factor 88 (MyD88), a pivotal adaptor that bridges toll-like receptors to their downstream signaling by recruiting the signaling complex called 'myddosome', was up-regulated in the medial prefrontal cortex (mPFC) after exposure to chronic social defeat stress (CSDS) or severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein. The inducible expression of MyD88 in the mPFC primed neuroinflammation and conferred stress susceptibility via amplifying immune danger signals, such as high-mobility group box 1 and SARS-CoV-2 spike protein. Overexpression of MyD88 aggravated, whereas knockout or pharmacological inhibition of MyD88 ameliorated CSDS-induced depressive-like behavior. Notably, TJ-M2010-5, a novel synthesized targeting inhibitor of MyD88 dimerization, alleviated both CSDS- and SARS-CoV-2 spike protein-induced depressive-like behavior. Taken together, our findings indicate that inhibiting MyD88 signaling represents a promising therapeutic strategy for stress-related mental disorders, such as MDD and COVID-19-related neuropsychiatric symptoms.


Subject(s)
COVID-19 , Depressive Disorder, Major , Myeloid Differentiation Factor 88 , Humans , Adaptor Proteins, Signal Transducing/metabolism , COVID-19/metabolism , COVID-19/psychology , Myeloid Differentiation Factor 88/metabolism , Neuroinflammatory Diseases , SARS-CoV-2/metabolism
8.
J Ethnopharmacol ; 301: 115763, 2023 Jan 30.
Article in English | MEDLINE | ID: covidwho-2105340

ABSTRACT

ETHNOPHARMACOLOGICAL RELEVANCE: Acute lung injury (ALI) is one of the fatal complications of respiratory virus infections such as influenza virus and coronavirus, which has high clinical morbidity and mortality. Jinhua Qinggan granules (JHQG) has been approved by China Food and Drug Administration in the treatment of H1N1 influenza and mild or moderate novel coronavirus disease 2019 (COVID-19), which is an herbal formula developed based on Maxingshigan decoction and Yinqiao powder that have been used to respiratory diseases in China for thousands of years. However, the underlying mechanism of JHQG in treating infectious diseases remains unclear. AIM OF THE STUDY: This study investigated the effects of JHQG on neutrophil apoptosis and key signaling pathways in lipopolysaccharide (LPS) -induced ALI mice in order to explore its mechanism of anti-inflammation. MATERIALS AND METHODS: The effect of JHQG on survival rate was observed in septic mouse model by intraperitoneal injection of LPS (20 mg/kg). To better pharmacological evaluation, the mice received an intratracheal injection of 5 mg/kg LPS. Lung histopathological changes, wet-to-dry ratio of the lungs, and MPO activity in the lungs and total protein concentration, total cells number, TNF-α, IL-1ß, IL-6, and MIP-2 levels in BALF were assessed. Neutrophil apoptosis rate was detected by Ly6G-APC/Annexin V-FITC staining. Key proteins associated with apoptosis including caspase 3/7 activity, Bcl-xL and Mcl-1 were measured by flow cytometry and confocal microscope, respectively. TLR4 receptor and its downstream signaling were analyzed by Western blot assay and immunofluorescence, respectively. RESULTS: JHQG treatment at either 6 or 12 g/kg/day resulted in 20% increase of survival in 20 mg/kg LPS-induced mice. In the model of 5 mg/kg LPS-induced mice, JHQG obviously decreased the total protein concentration in BALF, wet-to-dry ratio of the lungs, and lung histological damage. It also attenuated the MPO activity and the proportion of Ly6G staining positive neutrophils in the lungs, as well as the MIP-2 levels in BALF were reduced. JHQG inhibited the expression of Mcl-1 and Bcl-xL and enhanced caspase-3/7 activity, indicating that JHQG partially acted in promoting neutrophil apoptosis via intrinsic mitochondrial apoptotic pathway. The levels of TNF-α, IL-1ß, and IL-6 were significantly declined in LPS-induced mice treated with JHQG. Furthermore, JHQG reduced the protein expression of TLR4, MyD88, p-p65 and the proportion of nuclei p65, suggesting that JHQG treatment inhibited TLR4/MyD88/NF-κB pathway. CONCLUSION: JHQG reduced pulmonary inflammation and protected mice from LPS-induced ALI by promoting neutrophil apoptosis and inhibition of TLR4/MyD88/NF-κB pathway, suggesting that JHQG may be a promising drug for treatment of ALI.


Subject(s)
Acute Lung Injury , COVID-19 , Influenza A Virus, H1N1 Subtype , Mice , Animals , NF-kappa B/metabolism , Toll-Like Receptor 4/metabolism , Lipopolysaccharides/toxicity , Myeloid Differentiation Factor 88/metabolism , Neutrophils , Tumor Necrosis Factor-alpha/metabolism , Influenza A Virus, H1N1 Subtype/metabolism , Interleukin-6/metabolism , Myeloid Cell Leukemia Sequence 1 Protein/metabolism , Myeloid Cell Leukemia Sequence 1 Protein/therapeutic use , Acute Lung Injury/chemically induced , Acute Lung Injury/drug therapy , Acute Lung Injury/metabolism , Apoptosis
9.
J Virol ; 96(22): e0155522, 2022 11 23.
Article in English | MEDLINE | ID: covidwho-2097923

ABSTRACT

Porcine epidemic diarrhea virus (PEDV) is a re-emerging enteric coronavirus currently spreading in several nations and inflicting substantial financial damages on the swine industry. The currently available coronavirus vaccines do not provide adequate protection against the newly emerging viral strains. It is essential to study the relationship between host antiviral factors and the virus and to investigate the mechanisms underlying host immune response against PEDV infection. This study shows that heterogeneous nuclear ribonucleoprotein K (hnRNP K), the host protein determined by the transcription factor KLF15, inhibits the replication of PEDV by degrading the nucleocapsid (N) protein of PEDV in accordance with selective autophagy. hnRNP K was found to be capable of recruiting the E3 ubiquitin ligase, MARCH8, aiming to ubiquitinate N protein. Then, it was found that the ubiquitinated N protein could be delivered into autolysosomes for degradation by the cargo receptor NDP52, thereby inhibiting PEDV proliferation. Moreover, based on the enhanced MyD88 expression, we found that hnRNP K activated the interferon 1 (IFN-1) signaling pathway. Overall, the data obtained revealed a new mechanism of hnRNP K-mediated virus restriction wherein hnRNP K suppressed PEDV replication by degradation of viral N protein using the autophagic degradation pathway and by induction of IFN-1 production based on upregulation of MyD88 expression. IMPORTANCE The spread of the highly virulent PEDV in many countries is still leading to several epidemic and endemic outbreaks. To elucidate effective antiviral mechanisms, it is important to study the relationship between host antiviral factors and the virus and to investigate the mechanisms underlying host immune response against PEDV infection. In the work, we detected hnRNP K as a new host restriction factor which can hinder PEDV replication through degrading the nucleocapsid protein based on E3 ubiquitin ligase MARCH8 and the cargo receptor NDP52. In addition, via the upregulation of MyD88 expression, hnRNP K could also activate the interferon (IFN) signaling pathway. This study describes a previously unknown antiviral function of hnRNP K and offers a new vision toward host antiviral factors that regulate innate immune response as well as a protein degradation pathway against PEDV infection.


Subject(s)
Coronavirus Infections , Heterogeneous-Nuclear Ribonucleoprotein K , Interferon Type I , Porcine epidemic diarrhea virus , Virus Replication , Animals , Antiviral Agents , Chlorocebus aethiops , Coronavirus Infections/veterinary , Heterogeneous-Nuclear Ribonucleoprotein K/genetics , Interferons , Myeloid Differentiation Factor 88 , Nucleocapsid Proteins/physiology , Porcine epidemic diarrhea virus/physiology , Swine , Swine Diseases/virology , Ubiquitin-Protein Ligases , Vero Cells , Interferon Type I/immunology
10.
Front Immunol ; 13: 996637, 2022.
Article in English | MEDLINE | ID: covidwho-2043454

ABSTRACT

Increased neutrophils and elevated level of circulating calprotectin are hallmarks of severe COVID-19 and they contribute to the dysregulated immune responses and cytokine storm in susceptible patients. However, the precise mechanism controlling calprotectin production during SARS-CoV-2 infection remains elusive. In this study, we showed that Dok3 adaptor restrains calprotectin production by neutrophils in response to SARS-CoV-2 spike (S) protein engagement of TLR4. Dok3 recruits SHP-2 to mediate the de-phosphorylation of MyD88 at Y257, thereby attenuating downstream JAK2-STAT3 signaling and calprotectin production. Blocking of TLR4, JAK2 and STAT3 signaling could prevent excessive production of calprotectin by Dok3-/- neutrophils, revealing new targets for potential COVID-19 therapy. As S protein from SARS-CoV-2 Delta and Omicron variants can activate TLR4-driven calprotectin production in Dok3-/- neutrophils, our study suggests that targeting calprotectin production may be an effective strategy to combat severe COVID-19 manifestations associated with these emerging variants.


Subject(s)
Adaptor Proteins, Signal Transducing , COVID-19 , Spike Glycoprotein, Coronavirus , Adaptor Proteins, Signal Transducing/metabolism , Humans , Leukocyte L1 Antigen Complex , Myeloid Differentiation Factor 88/metabolism , Neutrophils/metabolism , SARS-CoV-2 , Toll-Like Receptor 4/metabolism
12.
J Virol ; 96(10): e0007022, 2022 05 25.
Article in English | MEDLINE | ID: covidwho-1832352

ABSTRACT

In global infection and serious morbidity and mortality, porcine epidemic diarrhea virus (PEDV) has been regarded as a dreadful porcine pathogen, but the existing commercial vaccines are not enough to fully protect against the epidemic strains. Therefore, it is of great necessity to feature the PEDV-host interaction and develop efficient countermeasures against viral infection. As an RNA/DNA protein, the trans-active response DNA binding protein (TARDBP) plays a variety of functions in generating and processing RNA, including transcription, splicing, transport, and mRNA stability, which have been reported to regulate viral replication. The current work aimed to detect whether and how TARDBP influences PEDV replication. Our data demonstrated that PEDV replication was significantly suppressed by TARDBP, regulated by KLF16, which targeted its promoter. We observed that through the proteasomal and autophagic degradation pathway, TARDBP inhibited PEDV replication via the binding as well as degradation of PEDV-encoded nucleocapsid (N) protein. Moreover, we found that TARDBP promoted autophagic degradation of N protein via interacting with MARCHF8, an E3 ubiquitin ligase, as well as NDP52, a cargo receptor. We also showed that TARDBP promoted host antiviral innate immune response by inducing interferon (IFN) expression through the MyD88-TRAF3-IRF3 pathway during PEDV infection. In conclusion, these data revealed a new antiviral role of TARDBP, effectively suppressing PEDV replication through degrading virus N protein via the proteasomal and autophagic degradation pathway and activating type I IFN signaling via upregulating the expression of MyD88. IMPORTANCE PEDV refers to the highly contagious enteric coronavirus that has quickly spread globally and generated substantial financial damage to the global swine industry. During virus infection, the host regulates the innate immunity and autophagy process to inhibit virus infection. However, the virus has evolved plenty of strategies with the purpose of limiting IFN-I production and autophagy processes. Here, we identified that TARDBP expression was downregulated via the transcription factor KLF16 during PEDV infection. TARDBP could inhibit PEDV replication through the combination as well as degradation of PEDV-encoded nucleocapsid (N) protein via proteasomal and autophagic degradation pathways and promoted host antiviral innate immune response by inducing IFN expression through the MyD88-TRAF3-IRF3 pathway. In sum, our data identify a novel antiviral function of TARDBP and provide a better grasp of the innate immune response and protein degradation pathway against PEDV infection.


Subject(s)
Coronavirus Infections , DNA-Binding Proteins , Interferon Type I , Porcine epidemic diarrhea virus , Virus Replication , Animals , Coronavirus Infections/veterinary , DNA-Binding Proteins/metabolism , Immunity, Innate , Interferon Regulatory Factor-3/metabolism , Interferon Type I/metabolism , Myeloid Differentiation Factor 88/metabolism , Nucleocapsid Proteins/metabolism , Porcine epidemic diarrhea virus/genetics , Porcine epidemic diarrhea virus/physiology , RNA/metabolism , Signal Transduction , Swine , TNF Receptor-Associated Factor 3/metabolism
13.
mBio ; 12(4): e0159821, 2021 08 31.
Article in English | MEDLINE | ID: covidwho-1360544

ABSTRACT

The gut microbiota plays a critical role in the induction of adaptive immune responses to influenza virus infection. However, the role of nasal bacteria in the induction of the virus-specific adaptive immunity is less clear. Here, we found that disruption of nasal bacteria by intranasal application of antibiotics before influenza virus infection enhanced the virus-specific antibody response in a MyD88-dependent manner. Similarly, disruption of nasal bacteria by lysozyme enhanced antibody responses to intranasally administered influenza virus hemagglutinin (HA) vaccine in a MyD88-dependent manner, suggesting that intranasal application of antibiotics or lysozyme could release bacterial pathogen-associated molecular patterns (PAMPs) from disrupted nasal bacteria that act as mucosal adjuvants by activating the MyD88 signaling pathway. Since commensal bacteria in the nasal mucosal surface were significantly lower than those in the oral cavity, intranasal administration of HA vaccine alone was insufficient to induce the vaccine-specific antibody response. However, intranasal supplementation of cultured oral bacteria from a healthy human volunteer enhanced antibody responses to an intranasally administered HA vaccine. Finally, we demonstrated that oral bacteria combined with an intranasal vaccine protect from influenza virus and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Our results reveal the role of nasal bacteria in the induction of the virus-specific adaptive immunity and provide clues for developing better intranasal vaccines. IMPORTANCE Intranasal vaccination induces the nasal IgA antibody which is protective against respiratory viruses, such as influenza virus and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Therefore, understanding how mucosal immune responses are elicited following viral infection is important for developing better vaccines. Here, we focused on the role of nasal commensal bacteria in the induction of immune responses following influenza virus infection. To deplete nasal bacteria, we intranasally administered antibiotics to mice before influenza virus infection and found that antibiotic-induced disruption of nasal bacteria could release bacterial components which stimulate the virus-specific antibody responses. Since commensal bacteria in nasal mucosa were significantly lower than those in the oral cavity, intranasal administration of split virus vaccine alone was insufficient to induce the vaccine-specific antibody response. However, intranasal supplementation of cultured oral bacteria from a healthy human volunteer enhanced antibody responses to the intranasally administered vaccine. Therefore, both integrity and amounts of nasal bacteria may be critical for an effective intranasal vaccine.


Subject(s)
Bacteria/immunology , COVID-19 Vaccines/immunology , COVID-19/prevention & control , Influenza Vaccines/immunology , Nasal Mucosa/microbiology , Orthomyxoviridae Infections/prevention & control , Adaptive Immunity/immunology , Adjuvants, Immunologic , Administration, Intranasal , Animals , Antibodies, Viral/immunology , Cell Line , Chlorocebus aethiops , Dogs , Hemagglutinin Glycoproteins, Influenza Virus/immunology , Immunity, Mucosal/immunology , Influenza A Virus, H1N1 Subtype/immunology , Madin Darby Canine Kidney Cells , Mice , Mice, Inbred BALB C , Myeloid Differentiation Factor 88/metabolism , Nasal Mucosa/immunology , Pathogen-Associated Molecular Pattern Molecules/immunology , SARS-CoV-2/immunology , Vaccination/methods , Vero Cells
14.
Nat Immunol ; 22(7): 829-838, 2021 07.
Article in English | MEDLINE | ID: covidwho-1220263

ABSTRACT

The innate immune response is critical for recognizing and controlling infections through the release of cytokines and chemokines. However, severe pathology during some infections, including SARS-CoV-2, is driven by hyperactive cytokine release, or a cytokine storm. The innate sensors that activate production of proinflammatory cytokines and chemokines during COVID-19 remain poorly characterized. In the present study, we show that both TLR2 and MYD88 expression were associated with COVID-19 disease severity. Mechanistically, TLR2 and Myd88 were required for ß-coronavirus-induced inflammatory responses, and TLR2-dependent signaling induced the production of proinflammatory cytokines during coronavirus infection independent of viral entry. TLR2 sensed the SARS-CoV-2 envelope protein as its ligand. In addition, blocking TLR2 signaling in vivo provided protection against the pathogenesis of SARS-CoV-2 infection. Overall, our study provides a critical understanding of the molecular mechanism of ß-coronavirus sensing and inflammatory cytokine production, which opens new avenues for therapeutic strategies to counteract the ongoing COVID-19 pandemic.


Subject(s)
COVID-19/immunology , Coronavirus Envelope Proteins/metabolism , Cytokine Release Syndrome/immunology , SARS-CoV-2/immunology , Toll-Like Receptor 2/metabolism , Animals , COVID-19/complications , COVID-19/diagnosis , COVID-19/virology , Chlorocebus aethiops , Cytokine Release Syndrome/diagnosis , Cytokines/metabolism , Disease Models, Animal , Female , Gene Expression Profiling , Humans , Immunity, Innate/drug effects , Leukocytes, Mononuclear , Macrophages , Male , Mice , Mice, Knockout , Myeloid Differentiation Factor 88/genetics , Myeloid Differentiation Factor 88/metabolism , Primary Cell Culture , SARS-CoV-2/metabolism , SARS-CoV-2/pathogenicity , Severity of Illness Index , Signal Transduction/drug effects , Signal Transduction/genetics , Signal Transduction/immunology , Toll-Like Receptor 2/antagonists & inhibitors , Toll-Like Receptor 2/genetics , Vero Cells , COVID-19 Drug Treatment
15.
Immunol Res ; 69(2): 117-128, 2021 04.
Article in English | MEDLINE | ID: covidwho-1174003

ABSTRACT

The continuous emergence of infectious pathogens along with antimicrobial resistance creates a need for an alternative approach to treat infectious diseases. Targeting host factor(s) which are critically involved in immune signaling pathways for modulation of host immunity offers to treat a broad range of infectious diseases. Upon pathogen-associated ligands binding to the Toll-like/ IL-1R family, and other cellular receptors, followed by recruitment of intracellular signaling adaptor proteins, primarily MyD88, trigger the innate immune responses. But activation of host innate immunity strongly depends on the correct function of MyD88 which is tightly regulated. Dysregulation of MyD88 may cause an imbalance that culminates to a wide range of inflammation-associated syndromes and diseases. Furthermore, recent reports also describe that MyD88 upregulation with many viral infections is linked to decreased antiviral type I IFN response, and MyD88-deficient mice showed an increase in survivability. These reports suggest that MyD88 is also negatively involved via MyD88-independent pathways of immune signaling for antiviral type I IFN response. Because of its expanding role in controlling host immune signaling pathways, MyD88 has been recognized as a potential drug target in a broader drug discovery paradigm. Targeting BB-loop of MyD88, small molecule inhibitors were designed by structure-based approach which by blocking TIR-TIR domain homo-dimerization have shown promising therapeutic efficacy in attenuating MyD88-mediated inflammatory impact, and increased antiviral type I IFN response in experimental mouse model of diseases. In this review, we highlight the reports on MyD88-linked immune response and MyD88-targeted therapeutic approach with underlying mechanisms for controlling inflammation and antiviral type I IFN response. HIGHLIGHTS: • Host innate immunity is activated upon PAMPs binding to PRRs followed by immune signaling through TIR domain-containing adaptor proteins mainly MyD88. • Structure-based approach led to develop small-molecule inhibitors which block TIR domain homodimerization of MyD88 and showed therapeutic efficacy in limiting severe inflammation-associated impact in mice. • Therapeutic intervention of MyD88 also showed an increase in antiviral effect with strong type I IFN signaling linked to increased phosphorylation of IRFs via MyD88-independent pathway. • MyD88 inhibitors might be potentially useful as a small-molecule therapeutics for modulation of host immunity against inflammatory diseases and antiviral therapy. • However, prior clinical use of more in-depth efforts should be focused for suitability of the approach in deploying to complex diseases including COPD and COVID-19 in limiting inflammation-associated syndrome to infection.


Subject(s)
Drug Delivery Systems , Immunity, Innate/drug effects , Myeloid Differentiation Factor 88 , Virus Diseases , Animals , Disease Models, Animal , Humans , Mice , Myeloid Differentiation Factor 88/antagonists & inhibitors , Myeloid Differentiation Factor 88/immunology , Virus Diseases/drug therapy , Virus Diseases/immunology
16.
J Ethnopharmacol ; 275: 114063, 2021 Jul 15.
Article in English | MEDLINE | ID: covidwho-1164034

ABSTRACT

ETHNOPHARMACOLOGICAL RELEVANCE: Fufang-Yinhua-Jiedu Granules (FFYH) optimized from a Yin-Qiao-San, as traditional Chinese medicine (TCM), was used to treat influenza and upper respiratory tract infection and was recommended for the prevention and treatment of SARS in 2003 and current COVID-19 in Anhui Province in 2020. AIM OF STUDY: In the clinical studies, FFYH was very effective for the treatment of influenza, but the mechanism of action against influenza A virus remains unclear. In the present study, we investigated the antiviral effect of FFYH against influenza A virus in vitro and vivo. Moreover, the potential mechanism of FFYH against influenza A virus in vivo was investigated for the first time. MATERIALS AND METHODS: CPE inhibition assay and HA assay were used to evaluate the in vitro antiviral effects of FFYH against influenza A virus H1N1, H3N2, H5N1, H7N9 and H9N2. Mice were used to evaluate the antiviral effect of FFYH in vivo with ribavirin and lianhuaqingwen as positive controls. RT-PCR was used to quantify the mRNA transcription of TNF-α, IL-6, IFN-γ, IP10, and IL-1ß mRNA. ELISA was used to examine the expression of inflammatory factors such as TNF-α, IL-6, IFN-γ, IP10, and IL-1ß in sera. The blood parameters were analyzed with auto hematology analyzer. Moreover, the potential mechanism of FFYH against influenza A virus in vivo was also investigated. RESULTS: FFYH showed a broad-spectrum of antiviral activity against H1N1, H3N2, H5N1, H7N9, and H9N2 influenza A viruses. Furthermore, FFYH dose-dependently increased the survival rate, significantly prolonged the median survival time of mice, and markedly reduced lung injury caused by influenza A virus. Also, FFYH significantly improve the sick signs, food taken, weight loss, blood parameters, lung index, and lung pathological changes. Moreover, FFYH could markedly inhibit the inflammatory cytokine expression of TNF-α, IL-6, IFN-γ, IP10, IL-10, and IL-1ß mRNA or protein via inhibition of the TLR7/MyD88/NF-κB signaling pathway in vivo. CONCLUSION: FFYH not only showed a broad-spectrum of anti-influenza virus activity in vitro, but also exhibited a significant protective effect against lethal influenza virus infection in vivo. Furthermore, our results indicated that the in vivo antiviral effect of FFYH against influenza virus may be attributed to suppressing the expression of inflammatory cytokines via regulating the TLR7/MyD88/NF-κB signaling pathway. These findings provide evidence for the clinical treatment of influenza A virus infection with FFYH.


Subject(s)
Anti-Inflammatory Agents/pharmacology , Antiviral Agents/pharmacology , Drugs, Chinese Herbal/pharmacology , Influenza A virus/drug effects , Lung/drug effects , Membrane Glycoproteins/metabolism , Myeloid Differentiation Factor 88/metabolism , Orthomyxoviridae Infections/drug therapy , Toll-Like Receptor 7/metabolism , A549 Cells , Animals , Cytokines/genetics , Cytokines/metabolism , Disease Models, Animal , Dogs , Host-Pathogen Interactions , Humans , Inflammation Mediators/metabolism , Influenza A virus/pathogenicity , Lung/immunology , Lung/metabolism , Lung/virology , Madin Darby Canine Kidney Cells , Mice, Inbred ICR , NF-kappa B/metabolism , Orthomyxoviridae Infections/immunology , Orthomyxoviridae Infections/metabolism , Orthomyxoviridae Infections/virology , Signal Transduction , Virus Replication/drug effects
17.
Int J Obes (Lond) ; 45(5): 1152-1154, 2021 05.
Article in English | MEDLINE | ID: covidwho-1104457

ABSTRACT

COVID-19 is a pandemic disease caused by a coronavirus, designed as SARS CoV-2, whose clinical presentation is widely variable, with most patients having mild or no symptoms, but others developing a malign disease with multi-organ failure and even death. Accumulating data from different populations have shown that obesity is a risk factor for a severe evolution of the disease, however, the mechanisms that explain this association are not clearly understood. An ominous evolution of COVID-19 has been attributed to an exacerbated inflammatory response, designed as "cytokine storm" with augmented production of cytokines/chemokines through the activation of toll-like receptors (TLR) by pathogen-associated molecular patterns, that triggers an inflammatory downstream response, mediated in part by the adaptor molecule, myeloid differentiation factor 88 (MyD88). Previous studies have reported an increased expression of MyD88 and TLRs in people with obesity, mainly in those with metabolic complications. Therefore, we hypothesize, that an underlying increased Myd88/TLR signaling may predispose to patients with obesity to develop an exaggerated and dangerous inflammatory reaction against SARS CoV-2 infection, explaining at least in part, the higher severity of COVID-19. In addition, MyD88/TLR signaling in people with obesity could have a role in the development of several chronic diseases.


Subject(s)
COVID-19 , Myeloid Differentiation Factor 88/metabolism , Obesity , Toll-Like Receptors/metabolism , COVID-19/complications , COVID-19/immunology , COVID-19/physiopathology , Cytokine Release Syndrome/immunology , Humans , Obesity/complications , Obesity/immunology , Obesity/physiopathology , Pandemics , Risk Factors , SARS-CoV-2 , Signal Transduction/immunology
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