Advances in Antiviral Therapies Targeting Toll-like Receptors

Discovery and development of INNA-051, a TLR2/6 agonist for the prevention of complications resulting from viral respiratory infections

Viral respiratory infection is associated with significant morbidity and mortality. The diversity of viruses implicated, coupled with their propensity for mutation, ignited an interest in host-directed antiviral therapies effective across a wide range of viral variants. Toll-like receptors (TLRs) are potential targets for the development of broad-spectrum antivirals given their central role in host immune defenses. Synthetic agonists of TLRs have been shown to boost protective innate immune responses against respiratory viruses. However, clinical success was hindered by short duration of benefit and/or induction of systemic adverse effects. INNA-051, a TLR2/6 agonist, is in development as an intranasal innate immune enhancer for prophylactic treatment in individuals at risk of complications resulting from respiratory viral infections. In vivo animal studies demonstrated the efficacy as prophylaxis against multiple viruses including SARS-CoV-2, influenza, and rhinovirus. Early clinical trials demonstrated an acceptable safety and tolerability profile. Intranasal delivery to the primary site of infection in humans induced a local innate host defense response characterized by innate immune cell infiltration into the nasal epithelium and activation and antiviral response genes. Taken together, the preclinical and clinical data on INNA-051 support further investigation of its use in community infection settings.

Nanoparticle-Based Therapies for Neurotropic Viral Infections: Mechanisms, Challenges, and Future Prospects

Neurotropic viral infections pose a significant challenge due to their ability to target the central nervous system and cause severe neurological complications. Traditional antiviral therapies face limitations in effectively treating these infections, primarily due to the blood-brain barrier, which restricts the delivery of therapeutic agents to the central nervous system. Nanoparticle-based therapies have emerged as a promising approach to overcome these challenges. Nanoparticles offer unique properties that facilitate drug delivery across biological barriers, such as the blood-brain barrier, and can be engineered to possess antiviral activities.

A TLR4-Targeting Bioactive Peptide Hydrogel to Regulate Immune-Microenvironment for Diabetic Wound Repair

Persistent inflammation and disrupted immunoregulation are critical factors in impeding diabetic wound healing. While immunoregulatory hydrogel dressings hold significant promise for clinical applications in diabetic wound healing, the current application often demands intricate interventions and high-cost treatments involving cytokines and cell therapies. The development of single component immunoregulatory hydrogels remains a complex challenge. To address this issue, an active peptide hydrogel with immunoregulatory properties targeting the TLR4/NF-kB pathway, aiming to promote rapid diabetic wound healing, is engineered. The hydrogel sequence comprises naphthalene derivative, phenylalanine, and glycine to modulate hydrophilic/hydrophobic characteristics. The amino group on arginine contributes to tissue adhesion and regulation of intermolecular forces, ultimately yielding stable gels. The results underscore the formation of the peptide hydrogel (NFA) via the physical crosslinking of self-assembled nanofibers in water, thereby affording both excellent injectability and tissue adhesion. Notably, NFA demonstrates significant potential in promoting wound healing in a mouse model with full-thickness wounds by regulating macrophage responses in the inflammatory microenvironment through the TLR4/NF-kB pathway.

Immunoinformatics-based multi-epitope vaccine design for the re-emerging monkeypox virus

BACKGROUND

On May 7, 2022, WHO reported a new monkeypox case. By May 2023 over 80,000 cases had been reported worldwide outside previously endemic nations. (This primarily affected the men who have sex with men (MSM) community in rich nations). The present research aims to develop a multi-epitope vaccine for the monkeypox virus (MPXV) using structural and cell surface proteins.

METHODS

The first part of the research involved retrieving protein sequences. The Immune Epitope Database (IEDB) was then used to analyze the B and T lymphocyte epitopes. After analyzing the sensitizing properties, toxicity, antigenicity, and molecular binding, appropriate linkers were utilizedto connect selected epitopes to adjuvants, and the structure of the vaccine was formulated. Algorithms from the field of immunoinformatics predicted the secondary and tertiary structures of vaccines. The physical, chemical, and structural properties were refined and validated to achieve maximum stability. Molecular docking and molecular dynamic simulations were subsequently employed to assess the vaccine's efficacy. Afterward, the ability of the vaccine to interact with toll-like receptors 3 and 4 (TLR3 and TLR4) was evaluated. Finally, the optimized sequence was then introduced into the Escherichia coli (E. coli) PET30A + vector.

RESULTS

An immunoinformatics evaluation suggested that such a vaccine might be safe revealed that this vaccine is safe, hydrophilic, temperature- and condition-stable, and can stimulate innate immunity by binding to TLR3 and TLR4.

CONCLUSION

Our findings suggest that the first step in MPXV pathogenesis is structural and cell surface epitopes. In this study, the most effective and promising epitopes were selected and designed throughprecision servers. Furthermore,through the utilization of multi-epitope structures and a combination of two established adjuvants, this research has the potential to be a landmarkin developing an antiviralvaccine against MPXV. However, additional in vitro and in vivo tests are required to confirm these results.

Contribution of T- and B-cell intrinsic toll-like receptors to the adaptive immune response in viral infectious diseases

Toll-like receptors (TLRs) comprise a class of highly conserved molecules that recognize pathogen-associated molecular patterns and play a vital role in host defense against multiple viral infectious diseases. Although TLRs are highly expressed on innate immune cells and play indirect roles in regulating antiviral adaptive immune responses, intrinsic expression of TLRs in adaptive immune cells, including T cells and B cells, cannot be ignored. TLRs expressed in CD4 + and CD8 + T cells play roles in enhancing TCR signal-induced T-cell activation, proliferation, function, and survival, serving as costimulatory molecules. Gene knockout of TLR signaling molecules has been shown to diminish antiviral adaptive immune responses and affect viral clearance in multiple viral infectious animal models. These results have highlighted the critical role of TLRs in the long-term immunological control of viral infection. This review summarizes the expression and function of TLR signaling pathways in T and B cells, focusing on the in vitro and vivo mechanisms and effects of intrinsic TLR signaling in regulating T- and B-cell responses during viral infection. The potential clinical use of TLR-based immune regulatory drugs for viral infectious diseases is also explored.

Identification and immunological evaluation of novel TLR2 agonists through structural optimization of Diprovocim

As an important family member of Toll-like receptors (TLRs), TLR2 can recognize various pathogen-associated molecular patterns (PAMPs) such as bacteria and viral components. Accumulating evidence demonstrates that TLR2 agonists play a critical role in cancer immunotherapy and infectious diseases. Diprovocim is the most potent small molecule TLR2 agonist known, showing remarkably immune adjuvant activity in mice. However, the further clinical research and development of Diprovocim was hampered because of its structural complexity as well as high molecular weight. Here, we designed and synthesized 21 structurally simplified derivatives of Diprovocim, performed their TLR2 agonistic activities by HEK-Blue hTLR2 SEAP assay, and evaluated the toxicity in two human normal cell lines. Compounds B3-B4 and B9-B12 with excellent TLR2 agonistic activity were found through the structure-activity relationship study. Among them, diastereomer B10 and B12 substituted (S)-2-phenylcyclopropylamide side chain of Diprovocim with simple (R)- and (S)-n-butyl groups exhibited comparable TLR2 agonistic activities with EC₅₀ values of 35 nM and 39 nM, respectively. ELISA and western blot experiments on THP-1 cells showed that B10 and B12 displayed remarkable immunostimulatory activity in the release of various inflammatory cytokines through activating MyD88-dependent NF-κB and MAPK signaling pathways. Importantly, B10 and B12 have less structural complexity and better safety compared to Diprovocim, and the chiral center of right pyrrolidine ring has negligible influence on TLR2 activition. Our study provides simplified Diprovocim derivatives with high agonistic activity, providing a clue to further optimize Diprovocim.

Toll-like Receptor Mediation in SARS-CoV-2: A Therapeutic Approach

The innate immune system facilitates defense mechanisms against pathogen invasion and cell damage. Toll-like receptors (TLRs) assist in the activation of the innate immune system by binding to pathogenic ligands. This leads to the generation of intracellular signaling cascades including the biosynthesis of molecular mediators. TLRs on cell membranes are adept at recognizing viral components. Viruses can modulate the innate immune response with the help of proteins and RNAs that downregulate or upregulate the expression of various TLRs. In the case of COVID-19, molecular modulators such as type 1 interferons interfere with signaling pathways in the host cells, leading to an inflammatory response. Coronaviruses are responsible for an enhanced immune signature of inflammatory chemokines and cytokines. TLRs have been employed as therapeutic agents in viral infections as numerous antiviral Food and Drug Administration-approved drugs are TLR agonists. This review highlights the therapeutic approaches associated with SARS-CoV-2 and the TLRs involved in COVID-19 infection.

PGRMC1 Exerts Its Function of Anti-Influenza Virus in the Central Nervous System

The influenza A virus (IAV) infection is usually restricted to the respiratory tract and only rarely enters the central nervous system (CNS) and causes neurological symptoms. However, the roles of host factors involved in IAV infection in the CNS remain largely undetermined. Therefore, we aimed to characterize the host responses to IAV infection in the brain. We isolated a strain of IAV H5N6, which is neurotoxic and highly pathogenic to mice. High-throughput RNA sequencing (RNA-seq) revealed 240 differentially expressed genes in IAV-infected brains. Among the significantly downregulated genes, we focused on the gene encoding progesterone receptor membrane component-1 (PGRMC1) and observed that IAV H5N6 infection clearly inhibited PGRMC1 in both neuroblastoma and glioma cells. Furthermore, treatment with AG205, a PGRMC1-specific inhibitor, or PGRMC1 knockout promoted H5N6 multiplication in vitro, while overexpression of PGRMC1 resulted in opposite effects. Furthermore, AG205 treatment or PGRMC1 knockout significantly inhibited the retinoic acid-inducible gene I (RIG-I)-mediated interferon beta (IFN-β) signaling pathway and reduced the levels of several antiviral proteins (Mx1 and ISG15). In addition, PGRMC1-mediated regulation of IFN signaling relied on inhibition of the expression and ubiquitination of RIG-I. The loss of PGRMC1 leads to an increased susceptibility of mice (brain and lung) to influenza A virus infection. Conclusively, our results show for the first time that IAV H5N6 downregulates PGRMC1 expression to contribute to virus proliferation by inhibiting RIG-I-mediated IFN-β production in the brain. These findings may offer new insights regarding the interplay between IAV and host factors that may impact IAV pathogenicity in the brain.

IMPORTANCE Central nervous system (CNS) disease is one of the most common extra-respiratory tract complications of influenza A virus (IAV) infections. However, there is still little knowledge about IAV regulating host responses in brain. In this study, we identified progesterone receptor membrane component-1 (PGRMC1) as a novel host factor involved in the replication and propagation of IAV H5N6 in the host brain. We also observed that PGRMC1 antagonism was required for viral evasion from the host immune response during IAV infection via inhibition of the retinoic acid-inducible gene I (RIG-I)-mediated interferon beta (IFN-β) signaling pathway and downstream antiviral gene expression. This study revealed a newly identified regulatory mechanism used by IAV H5N6 to ensure its life cycle in the CNS.

TLR2-mediated innate immune priming boosts lung anti-viral immunity

BACKGROUND

We assessed whether Toll-like receptor (TLR)2 activation boosts the innate immune response to rhinovirus infection, as a treatment strategy for virus-induced respiratory diseases.

METHODS

We employed treatment with a novel TLR2 agonist (INNA-X) prior to rhinovirus infection in mice, and INNA-X treatment in differentiated human bronchial epithelial cells derived from asthmatic-donors. We assessed viral load, immune cell recruitment, cytokines, type I and III interferon (IFN) production, as well as the lung tissue and epithelial cell immune transcriptome.

RESULTS

We show, in vivo, that a single INNA-X treatment induced innate immune priming characterised by low-level IFN-λ, Fas ligand, chemokine expression and airway lymphocyte recruitment. Treatment 7 days before infection significantly reduced lung viral load, increased IFN-β/λ expression and inhibited neutrophilic inflammation. Corticosteroid treatment enhanced the anti-inflammatory effects of INNA-X. Treatment 1 day before infection increased expression of 190 lung tissue immune genes. This tissue gene expression signature was absent with INNA-X treatment 7 days before infection, suggesting an alternate mechanism, potentially via establishment of immune cell-mediated mucosal innate immunity. In vitro, INNA-X treatment induced a priming response defined by upregulated IFN-λ, chemokine and anti-microbial gene expression that preceded an accelerated response to infection enriched for nuclear factor (NF)-κB-regulated genes and reduced viral loads, even in epithelial cells derived from asthmatic donors with intrinsic delayed anti-viral immune response.

CONCLUSION

Airway epithelial cell TLR2 activation induces prolonged innate immune priming, defined by early NF-κB activation, IFN-λ expression and lymphocyte recruitment. This response enhanced anti-viral innate immunity and reduced virus-induced airway inflammation.

Exploring SARS-COV-2 structural proteins to design a multi-epitope vaccine using immunoinformatics approach: An in silico study

In December 2019, a new virus called SARS-CoV-2 was reported in China and quickly spread to other parts of the world. The development of SARS-COV-2 vaccines has recently received much attention from numerous researchers. The present study aims to design an effective multi-epitope vaccine against SARS-COV-2 using the reverse vaccinology method. In this regard, structural proteins from SARS-COV-2, including the spike (S), envelope (E), membrane (M), and nucleocapsid (N) proteins, were selected as target antigens for epitope prediction. A total of five helper T lymphocytes (HTL) and five cytotoxic T lymphocytes (CTL) epitopes were selected after screening the predicted epitopes for antigenicity, allergenicity, and toxicity. Subsequently, the selected HTL and CTL epitopes were fused via flexible linkers. Next, the cholera toxin B-subunit (CTxB) as an adjuvant was linked to the N-terminal of the chimeric structure. The proposed vaccine was analyzed for the properties of physicochemical, antigenicity, and allergenicity. The 3D model of the vaccine construct was predicted and docked with the Toll-like receptor 4 (TLR4). The molecular dynamics (MD) simulation was performed to evaluate the stable interactions between the vaccine construct and TLR4. The immune simulation was also conducted to explore the immune responses induced by the vaccine. Finally, in silico cloning of the vaccine construct into the pET-28 (+) vector was conducted. The results obtained from all bioinformatics analysis stages were satisfactory; however, in vitro and in vivo tests are essential to validate these results.

Low compositions of human toll-like receptor 7/8-stimulating RNA motifs in the MERS-CoV, SARS-CoV and SARS-CoV-2 genomes imply a substantial ability to evade human innate immunity

Background

The innate immune system especially Toll-like receptor (TLR) 7/8 and the interferon pathway, constitutes an important first line of defense against single-stranded RNA viruses. However, large-scale, systematic comparisons of the TLR 7/8-stimulating potential of genomic RNAs of single-stranded RNA viruses are rare. In this study, a computational method to evaluate the human TLR 7/8-stimulating ability of single-stranded RNA virus genomes based on their human TLR 7/8-stimulating trimer compositions was used to analyze 1,002 human coronavirus genomes.

Results

The human TLR 7/8-stimulating potential of coronavirus genomic (positive strand) RNAs followed the order of NL63-CoV > HKU1-CoV >229E-CoV ≅ OC63-CoV > SARS-CoV-2 > MERS-CoV > SARS-CoV. These results suggest that among these coronaviruses, MERS-CoV, SARS-CoV and SARS-CoV-2 may have a higher ability to evade the human TLR 7/8-mediated innate immune response. Analysis with a logistic regression equation derived from human coronavirus data revealed that most of the 1,762 coronavirus genomic (positive strand) RNAs isolated from bats, camels, cats, civets, dogs and birds exhibited weak human TLR 7/8-stimulating potential equivalent to that of the MERS-CoV, SARS-CoV and SARS-CoV-2 genomic RNAs.

Conclusions

Prediction of the human TLR 7/8-stimulating potential of viral genomic RNAs may be useful for surveillance of emerging coronaviruses from nonhuman mammalian hosts.

T cell responses in respiratory viral infections and chronic obstructive pulmonary disease

ABSTRACT

Respiratory viruses are major human pathogens that cause approximately 200 million pneumonia cases annually and induce various comorbidities with chronic obstructive pulmonary disease (COPD), resulting in significant health concerns and economic burdens. Clinical manifestations in respiratory viral infections and inflammations vary from asymptomatic, mild, to severe, depending on host immune cell responses to pathogens and interactions with airway epithelia. We critically review the activation, effector, and regulation of T cells in respiratory virus infections and chronic inflammations associated with COPD. Crosstalk among T cells, innate immune cells, and airway epithelial cells is discussed as essential parts of pathogenesis and protection in viral infections and COPD. We emphasize the specificity of peptide antigens and the functional heterogeneity of conventional CD4+ and CD8+ T cells to shed some light on potential cellular and molecular candidates for the future development of therapeutics and intervention against respiratory viral infections and inflammations.

Prophylactic intranasal administration of a TLR2/6 agonist reduces upper respiratory tract viral shedding in a SARS-CoV-2 challenge ferret model

BACKGROUND

The novel human coronavirus SARS-CoV-2 is a major ongoing global threat with huge economic burden. Like all respiratory viruses, SARS-CoV-2 initiates infection in the upper respiratory tract (URT). Infected individuals are often asymptomatic, yet highly infectious and readily transmit virus. A therapy that restricts initial replication in the URT has the potential to prevent progression of severe lower respiratory tract disease as well as limiting person-to-person transmission.

METHODS

SARS-CoV-2 Victoria/01/2020 was passaged in Vero/hSLAM cells and virus titre determined by plaque assay. Challenge virus was delivered by intranasal instillation to female ferrets at 5.0 × 106 pfu/ml. Treatment groups received intranasal INNA-051, developed by Ena Respiratory. SARS-CoV-2 RNA was detected using the 2019-nCoV CDC RUO Kit and QuantStudio™ 7 Flex Real-Time PCR System. Histopathological analysis was performed using cut tissues stained with haematoxylin and eosin (H&E).

FINDINGS

We show that prophylactic intra-nasal administration of the TLR2/6 agonist INNA-051 in a SARS-CoV-2 ferret infection model effectively reduces levels of viral RNA in the nose and throat. After 5 days post-exposure to SARS-CoV-2, INNA-051 significantly reduced virus in throat swabs (p=<0.0001) by up to a 24 fold (96% reduction) and in nasal wash (p=0.0107) up to a 15 fold (93% reduction) in comparison to untreated animals.

INTERPRETATION

The results of our study support clinical development of a therapy based on prophylactic TLR2/6 innate immune activation in the URT, to reduce SARS-CoV-2 transmission and provide protection against COVID-19.

FUNDING

This work was funded by Ena Respiratory, Melbourne, Australia.

A domain-based vaccine construct against SARS-CoV-2, the causative agent of COVID-19 pandemic: development of self-amplifying mRNA and peptide vaccines

Introduction: Coronavirus disease 2019 (COVID-19) is undoubtedly the most challenging pandemic in the current century with more than 293,241 deaths worldwide since its emergence in late 2019 (updated May 13, 2020). COVID-19 is caused by a novel emerged coronavirus named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Today, the world needs crucially to develop a prophylactic vaccine scheme for such emerged and emerging infectious pathogens. Methods: In this study, we have targeted spike (S) glycoprotein, as an important surface antigen to identify its B- and T-cell immunodominant regions. We have conducted a multi-method B-cell epitope (BCE) prediction approach using different predictor algorithms to discover the most potential BCEs. Besides, we sought among a pool of MHC class I and II-associated peptide binders provided by the IEDB server through the strict cut-off values. To design a broad-coverage vaccine, we carried out a population coverage analysis for a set of candidate T-cell epitopes and based on the HLA allele frequency in the top most-affected countries by COVID-19 (update 02 April 2020). Results: The final determined B- and T-cell epitopes were mapped on the S glycoprotein sequence, and three potential hub regions covering the largest number of overlapping epitopes were identified for the vaccine designing (I531-N711; T717-C877; and V883-E973). Here, we have designed two domain-based constructs to be produced and delivered through the recombinant protein- and gene-based approaches, including (i) an adjuvanted domain-based protein vaccine construct (DPVC), and (ii) a self-amplifying mRNA vaccine (SAMV) construct. The safety, stability, and immunogenicity of the DPVC were validated using the integrated sequential (i.e. allergenicity, autoimmunity, and physicochemical features) and structural (i.e. molecular docking between the vaccine and human Toll-like receptors (TLRs) 4 and 5) analysis. The stability of the docked complexes was evaluated using the molecular dynamics (MD) simulations. Conclusion: These rigorous in silico validations supported the potential of the DPVC and SAMV to promote both innate and specific immune responses in preclinical studies.

Detection of Viral Infections by Innate Immunity

Pattern recognition receptors (PRRs) and inflammasomes are a key part of the anti-viral innate immune system as they detect conserved viral pathogen-associated molecular patterns (PAMPs). A successful host response to viral infections critically depend on the initial activation of PRRs by viruses, mainly by viral DNA and RNA. The signalling pathways activated by PRRs leads to the expression of pro-inflammatory cytokines, to recruit immune cells, and type I and type III interferons which leads to the induction of interferon stimulated genes (ISG), powerful virus restriction factors that establish the "antiviral state". Inflammasomes contribute to anti-viral responses through the maturation of interleukin (IL)-1 and IL-18 and through triggering pyroptotic cell death. The activity of the innate immune system along with the adaptive immune response normally leads to successful virus elimination, although disproportionate innate responses contribute to viral pathology. In this review we will discuss recent insights into the influence of PRR activation and inflammasomes on viral infections and what this means for the mammalian host. We will also comment on how specific PRRs and inflammasomes may be relevant to how SARS-CoV-2, the virus responsible for the current COVID-19 pandemic, interacts with host innate immunity.

Modulation of the Innate Immune Response by Targeting Toll-like Receptors: A Perspective on Their Agonists and Antagonists

Toll-like receptors (TLRs) are a class of proteins that recognize pathogen-associated molecular patterns (PAMPs) and damaged-associated molecular patterns (DAMPs), and they are involved in the regulation of innate immune system. These transmembrane receptors, localized at the cellular or endosomal membrane, trigger inflammatory processes through either myeloid differentiation primary response 88 (MyD88) or TIR-domain-containing adapter-inducing interferon-β (TRIF) signaling pathways. In the last decades, extensive research has been performed on TLR modulators and their therapeutic implication under several pathological conditions, spanning from infections to cancer, from metabolic disorders to neurodegeneration and autoimmune diseases. This Perspective will highlight the recent discoveries in this field, emphasizing the role of TLRs in different diseases and the therapeutic effect of their natural and synthetic modulators, and it will discuss insights for the future exploitation of TLR modulators in human health.

LncRNAs in the Type I Interferon Antiviral Response

The proper functioning of the immune system requires a robust control over a delicate equilibrium between an ineffective response and immune overactivation. Poor responses to viral insults may lead to chronic or overwhelming infection, whereas unrestrained activation can cause autoimmune diseases and cancer. Control over the magnitude and duration of the antiviral immune response is exerted by a finely tuned positive or negative regulation at the DNA, RNA, and protein level of members of the type I interferon (IFN) signaling pathways and on the expression and activity of antiviral and proinflammatory factors. As summarized in this review, committed research during the last decade has shown that several of these processes are exquisitely regulated by long non-coding RNAs (lncRNAs), transcripts with poor coding capacity, but highly versatile functions. After infection, viruses, and the antiviral response they trigger, deregulate the expression of a subset of specific lncRNAs that function to promote or repress viral replication by inactivating or potentiating the antiviral response, respectively. These IFN-related lncRNAs are also highly tissue- and cell-type-specific, rendering them as promising biomarkers or therapeutic candidates to modulate specific stages of the antiviral immune response with fewer adverse effects.

Immune Reconstitution Disorders: Spotlight on Interferons

Three decades of research in hematopoietic stem cell transplantation and HIV/AIDS fields have shaped a picture of immune restoration disorders. This manuscript overviews the molecular biology of interferon networks, the molecular pathogenesis of immune reconstitution inflammatory syndrome, and post-hematopoietic stem cell transplantation immune restoration disorders (IRD). It also summarizes the effects of thymic involution on T cell diversity, and the results of the assessment of diagnostic biomarkers of IRD, and tested targeted immunomodulatory treatments.

A cell-penetrating peptide blocks Toll-like receptor-mediated downstream signaling and ameliorates autoimmune and inflammatory diseases in mice

Toll-like receptors (TLRs) recognize pathogen/damage-associated molecular patterns and initiate inflammatory signaling cascades. Occasionally, overexpression of TLRs leads to the onset of numerous inflammatory diseases, necessitating the development of selective inhibitors to allow a protective yet balanced immune response. Here, we demonstrate that a novel peptide (TIP1) derived from Toll/interleukin-1 receptor (TIR) domain-containing adapter protein inhibited multiple TLR signaling pathways (MyD88-dependent and MyD88-independent) in murine and human cell lines. TIP1 also inhibited NLRP3-mediated IL-1β secretion, as we validated at both the protein and mRNA levels. Biophysical experiments confirmed that TIP1 specifically binds to the BB loop of the TLR4-TIR domain. Animal studies revealed that TIP1 inhibited the secretion of lipopolysaccharide (LPS)-induced proinflammatory cytokines in collagen-induced arthritis (CIA) and kaolin/carrageenan-induced arthritis (K/C) rodent models. TIP1 also rescued animals from sepsis and from LPS-induced kidney/liver damage. Importantly, TIP1 ameliorated the symptoms of rheumatoid arthritis in CIA and K/C rodent models, suggesting that TIP1 has therapeutic potential for the treatment of TLR-mediated autoimmune/inflammatory diseases.

Roles of Host Immunity in Viral Myocarditis and Dilated Cardiomyopathy

The pathogenesis of viral myocarditis includes both the direct damage mediated by viral infection and the indirect lesion resulted from host immune responses. Myocarditis can progress into dilated cardiomyopathy that is also associated with immunopathogenesis. T cell-mediated autoimmunity, antibody-mediated autoimmunity (autoantibodies), and innate immunity, working together, contribute to the development of myocarditis and dilated cardiomyopathy.

TLR4/MD2 specific peptides stalled in vivo LPS-induced immune exacerbation

Negative regulation of Toll-like receptor-4 (TLR4) is anticipated to control the pathogen-induced exaggerated immune response. However, effective TLR4 antagonists with scarce off-target effects are yet to be developed. To fill this void, we sought to design small peptide-inhibitors of the TLR4/MD2-LPS interaction. Here we report novel TLR4-antagonistic peptides (TAP), identified through phage display, endowed with the LPS-induced proinflammation inhibition, and confirmed in mice. TAPs-attributed TLR4-antagonism were initially evaluated through NF-κB inhibition in HEK-blue hTLR4 and RAW264.7 cells, and further reinforced by the downregulation of MAPKs (mitogen-activated protein kinases), NF-κB, interleukin 6, and suppression of the oxidative-stress products and iNOS in macrophages and human peripheral blood mononuclear cells (hPBMCs). Among these, TAP2 specifically halted the TLR4, but not other TLRs signaling, which was further confirmed by the biophysical kinetic assay. Finally, TAP2 diminished LPS-elicited systemic cytokine response in vivo, suggesting that TAPs, specifically TAP2, have the potential to treat TLR4-mediated immune ailments.