Tissue expression of human Toll-like receptors and differential regulation of Toll-like receptor mRNAs in leukocytes in response to microbes, their products, and cytokines

The Battle of LPS Clearance in Host Defense vs. Inflammatory Signaling

Lipopolysaccharide (LPS) in blood circulation causes endotoxemia and is linked to various disease conditions. Current treatments focus on preventing LPS from interacting with its receptor Toll-like receptor 4 (TLR4) and reducing inflammation. However, our body has a natural defense mechanism: reticuloendothelial cells in the liver rapidly degrade and inactivate much of the circulating LPS within minutes. But this LPS clearance mechanism is not perfect. Excessive LPS that escape this clearance mechanism cause systemic inflammatory damage through TLR4. Despite its importance, the role of reticuloendothelial cells in LPS elimination is not well-studied, especially regarding the specific cells, receptors, and mechanisms involved. This gap hampers the development of effective therapies for endotoxemia and related diseases. This review consolidates the current understanding of LPS clearance, narrates known and explores potential mechanisms, and discusses the relationship between LPS clearance and LPS signaling. It also aims to highlight key insights that can guide the development of strategies to reduce circulating LPS by way of bolstering host defense mechanisms. Ultimately, we seek to provide a foundation for future research that could lead to innovative approaches for enhancing the body's natural ability to clear LPS and thereby lower the risk of endotoxin-related inflammatory diseases, including sepsis.

Toll-like receptor 4 - a multifunctional virus recognition receptor

Since the initial description of Toll receptors in Drosophila and their mammalian counterparts Toll-like receptors (TLRs), numerous fundamental and applied studies have explored their crucial role as sensors of pathogen-associated molecular patterns (PAMPs). Among the ten human TLRs, TLR4 is particularly well known for its ability to detect lipopolysaccharides (LPS), a component of the Gram-negative bacterial cell wall. In addition to its archetypal functions, TLR4 is also a versatile virus sensor. This review provides a background on the discovery of TLR4 and how this knowledge laid a foundation for characterization of its diverse roles in antiviral responses, examined through genetic, biochemical, structural, and immunological approaches. These advances have led to a deeper understanding of the molecular functions that enable TLR4 to orchestrate multi-nodal control by professional antigen-presenting cells (APCs) to initiate appropriate and regulated antiviral immune responses.

The Raf kinase inhibitors Dabrafenib and Regorafenib impair Zika virus replication via distinct mechanisms

Zika virus (ZIKV) is a re-emerging mosquito-borne flavivirus that has been associated with congenital neurological defects in fetuses born to infected mothers. At present, no vaccine or antiviral therapy is available to combat this devastating disease. Repurposing drugs that target essential host factors exploited by viruses is an attractive therapeutic approach. Here, we screened a panel of clinically approved small-molecule kinase inhibitors for their antiviral effects against a clinical isolate of ZIKV and thoroughly characterized their mechanisms of action. We found that the Raf kinase inhibitors Dabrafenib and Regorafenib potently impair the replication of ZIKV, but not that of its close relative dengue virus. Time-of-addition experiments showed that both inhibitors target ZIKV infection at post-entry steps. We found that Dabrafenib, but not Regorafenib, interfered with ZIKV genome replication by impairing both negative- and positive-strand RNA synthesis. Regorafenib, on the other hand, altered steady-state viral protein levels, viral egress, and blocked NS1 secretion. We also observed Regorafenib-induced ER fragmentation in ZIKV-infected cells, which might contribute to its antiviral effects. Because these inhibitors target different steps of the ZIKV infection cycle, their use in combination therapy may amplify their antiviral effects which could be further explored for future therapeutic strategies against ZIKV and possibly other flaviviruses.

IMPORTANCE

There is an urgent need to develop effective therapeutics against re-emerging arboviruses associated with neurological disorders like Zika virus (ZIKV). We identified two FDA-approved kinase inhibitors, Dabrafenib and Regorafenib, as potent inhibitors of contemporary ZIKV strains at distinct stages of infection despite overlapping host targets. Both inhibitors reduced viral titers by ~1 to 2 log10 (~10-fold to 100-fold) with minimal cytotoxicity. Furthermore, we show that Dabrafenib inhibits ZIKV RNA replication whereas Regorafenib inhibits ZIKV translation and egress. Regorafenib has the added benefit of limiting NS1 secretion, which contributes to the pathogenesis and disease progression of several flaviviruses. Because these inhibitors affect distinct post-entry steps of ZIKV infection, their therapeutic potential may be amplified by combination therapy and likely does not require prophylactic administration. This study provides further insight into ZIKV-host interactions and has implications for the development of novel antivirals against ZIKV and possibly other flaviviruses.

Recent insights of PROTAC developments in inflammation-mediated and autoimmune targets: a critical review

According to the mounting evidence in the literature, pro-inflammatory mediators/targets activate multiple signalling pathways to trigger illnesses that are ultimately responsible for acute pain, chronic inflammatory diseases, and several auto-immune disorders. Conventional drugs have been ruled out since proteolysis-targeting chimeras (PROTACs) are poised to overcome the limitations of traditional therapies. These heterobifunctional molecules help to degrade the targeted proteins of interest through ubiquitination. This review encompasses current and future aspects of PROTACs in inflammation-mediated and autoimmune targets. Different key points are highlighted and discussed, such as why PROTACs are preferred in this disease area, drawbacks and lessons learnt from the past, the role of linkers in establishing crucial degradation, in vitro findings, pharmacokinetics, in silico parameters, limitations of PROTACs in clinical settings, and future outcomes.

Identification and verification of immune-related genes for diagnosing the progression of atherosclerosis and metabolic syndrome

BACKGROUND

Atherosclerosis and metabolic syndrome are the main causes of cardiovascular events, but their underlying mechanisms are not clear. In this study, we focused on identifying genes associated with diagnostic biomarkers and effective therapeutic targets associated with these two diseases.

METHODS

Transcriptional data sets of atherosclerosis and metabolic syndrome were obtained from GEO database. The differentially expressed genes were analyzed by RStudio software, and the function-rich and protein-protein interactions of the common differentially expressed genes were analyzed.Furthermore, the hub gene was screened by Cytoscape software, and the immune infiltration of hub gens was analyzed. Finally, relevant clinical blood samples were collected for qRT-PCR verification of the three most important hub genes.

RESULTS

A total of 1242 differential genes (778 up-regulated genes and 464 down-regulated genes) were screened from GSE28829 data set. A total of 1021 differential genes (492 up-regulated genes and 529 down-regulated genes) were screened from the data set GSE98895. Then 23 up-regulated genes and 11 down-regulated genes were screened by venn diagram. Functional enrichment analysis showed that cytokines and immune activation were involved in the occurrence and development of these two diseases. Through the construction of the Protein-Protein Interaction(PPI) network and Cytoscape software analysis, we finally screened 10 hub genes. The immune infiltration analysis was further improved. The results showed that the infiltration scores of 7 kinds of immune cells in GSE28829 were significantly different among groups (Wilcoxon Test < 0.05), while in GSE98895, the infiltration scores of 4 kinds of immune cells were significantly different between groups (Wilcoxon Test < 0.05). Spearman method was used to analyze the correlation between the expression of 10 key genes and 22 kinds of immune cell infiltration scores in two data sets. The results showed that there were 42 pairs of significant correlations between 10 genes and 22 kinds of immune cells in GSE28829 (|Cor| > 0.3 & P < 0.05). There were 41 pairs of significant correlations between 10 genes and 22 kinds of immune cells in GSE98895 (|Cor| > 0.3 & P < 0.05). Finally, our results identified 10 small molecules with the highest absolute enrichment value, and the three most significant key genes (CX3CR1, TLR5, IL32) were further verified in the data expression matrix and clinical blood samples.

CONCLUSION

We have established a co-expression network between atherosclerotic progression and metabolic syndrome, and identified key genes between the two diseases. Through the method of bioinformatics, we finally obtained 10 hub genes in As and MS, and selected 3 of the most significant genes (CX3CR1, IL32, TLR5) for blood PCR verification. This may be helpful to provide new research ideas for the diagnosis and treatment of AS complicated with MS.

MD-1 downregulation is associated with reduced cell surface CD180 expression in CLL

CD180 is a toll-like receptor that is highly expressed in complex with the MD-1 satellite molecule on the surface of B cells. In chronic lymphocytic leukaemia (CLL) however, the expression of CD180 is highly variable and overall, significantly reduced when compared to normal B cells. We have recently shown that reduced CD180 expression in CLL lymph nodes is associated with inferior overall survival. It was therefore important to better understand the causes of this downregulation through investigation of CD180 at the transcriptional and protein expression levels. Unexpectedly, we found CD180 RNA levels in CLL cells (n = 26) were comparable to those of normal B cells (n = 13), despite heterogeneously low expression of CD180 on the cell surface. We confirmed that CD180 RNA is translated into CD180 protein since cell surface CD180-negative cases presented with high levels of intracellular CD180 expression. Levels of MD-1 RNA were, however, significantly downregulated in CLL compared to normal controls. Together, these data suggest that changes in CD180 cell surface expression in CLL are not due to transcriptional downregulation, but defective post-translational stabilisation of the receptor due to MD-1 downregulation.

Immune Stimulation with Imiquimod to Best Face SARS-CoV-2 Infection and Prevent Long COVID

Through widespread immunization against SARS-CoV-2 prior to or post-infection, a substantial segment of the global population has acquired both humoral and cellular immunity, and there has been a notable reduction in the incidence of severe and fatal cases linked to this virus and accelerated recovery times for those infected. Nonetheless, a significant demographic, comprising around 20% to 30% of the adult population, remains unimmunized due to diverse factors. Furthermore, alongside those recovered from the infection, there is a subset of the population experiencing persistent symptoms referred to as Long COVID. This condition is more prevalent among individuals with underlying health conditions and immune system impairments. Some Long COVID pathologies stem from direct damage inflicted by the viral infection, whereas others arise from inadequate immune system control over the infection or suboptimal immunoregulation. There are differences in the serum cytokines and miRNA profiles between infected individuals who develop severe COVID-19 or Long COVID and those who control adequately the infection. This review delves into the advantages and constraints associated with employing imiquimod in human subjects to enhance the immune response during SARS-CoV-2 immunization. Restoration of the immune system can modify it towards a profile of non-susceptibility to SARS-CoV-2. An adequate immune system has the potential to curb viral propagation, mitigate symptoms, and ameliorate the severe consequences of the infection.

Mechanisms and Delivery of tRNA Therapeutics

Transfer ribonucleic acid (tRNA) therapeutics will provide personalized and mutation specific medicines to treat human genetic diseases for which no cures currently exist. The tRNAs are a family of adaptor molecules that interpret the nucleic acid sequences in our genes into the amino acid sequences of proteins that dictate cell function. Humans encode more than 600 tRNA genes. Interestingly, even healthy individuals contain some mutant tRNAs that make mistakes. Missense suppressor tRNAs insert the wrong amino acid in proteins, and nonsense suppressor tRNAs read through premature stop signals to generate full length proteins. Mutations that underlie many human diseases, including neurodegenerative diseases, cancers, and diverse rare genetic disorders, result from missense or nonsense mutations. Thus, specific tRNA variants can be strategically deployed as therapeutic agents to correct genetic defects. We review the mechanisms of tRNA therapeutic activity, the nature of the therapeutic window for nonsense and missense suppression as well as wild-type tRNA supplementation. We discuss the challenges and promises of delivering tRNAs as synthetic RNAs or as gene therapies. Together, tRNA medicines will provide novel treatments for common and rare genetic diseases in humans.

Effects of the commensal microbiota on spleen and mesenteric lymph node immune function: investigation in a germ-free piglet model

Commensal microbial-host interaction is crucial for host metabolism, growth, development, and immunity. However, research on microbial-host immunity in large animal models has been limited. This study was conducted to investigate the effects of the commensal microbiota on immune function in two model groups: germ-free (GF) and specific-pathogen-free (SPF) piglets. The weight and organ index of the spleen of the GF piglet were larger than those in the SPF piglet (P < 0.05). The histological structure of the red pulp area and mean area of germinal centers were larger in the SPF piglet than in the GF piglet (P < 0.05), whereas the areas of staining of B cells and T cells in the spleen and mesenteric lymph nodes (MLNs) were lower in the GF piglet (P < 0.05). We identified immune-related genes in the spleen and MLNs using RNA sequencing, and used real-time quantitative PCR to analyze the expression of core genes identified in gene set enrichment analysis. The expression levels of genes in the transforming growth factor-β/SMAD3 signaling pathway, Toll-like receptor 2/MyD88/nuclear factor-κB signaling pathway, and pro-inflammatory factor genes IL-6 and TNF-α in the spleen and MLNs were higher in the SPF piglet and in splenic lymphocytes compared with those in the GF and control group, respectively, under treatment with acetic acid, propionic acid, butyric acid, lipopolysaccharide (LPS), or concanavalin A (ConA). The abundances of plasma cells, CD8++ T cells, follicular helper T cells, and resting natural killer cells in the spleen and MLNs were significantly greater in the SPF piglet than in the GF piglet (P < 0.05). In conclusion, the commensal microbiota influenced the immune tissue structure, abundances of immune cells, and expression of immune-related pathways, indicating the importance of the commensal microbiota for spleen and MLNs development and function. In our study, GF piglet was used as the research model, eliminating the interference of microbiota in the experiment, and providing a suitable and efficient large animal research model for exploring the mechanism of "microbial-host" interactions.

CIRP increases Foxp3+ regulatory T cells and inhibits development of Th17 cells by enhancing TLR4-IL-2 signaling in the late phase of sepsis

BACKGROUND

T helper (Th) cell imbalances have been associated with the pathophysiology of sepsis, including the Th1/Th2 and Th17/T regulatory cells (Treg) paradigms. Cold-inducible RNA-binding protein (CIRP), a novel damage-associated molecular pattern (DAMP) was reported that could induce T cell activation, and skew CD4+ T cells towards a Th1 profile. However, the effect and underlying mechanisms of CIRP on Th17/Treg differentiation in sepsis still remains unknown.

METHODS

A prospective exploratory study including patients with sepsis was conducted. Blood samples were collected from patients on days 0, 3 and 7 on admission. The serum CIRP and peripheral blood Treg/Th17 percentage was determined by ELISA and flow cytometry. CD4+ T cells from the spleen and lymph nodes of mice with experimental sepsis were collected after treatment with normal saline (NS), recombinant murine CIRP (rmCIRP) and C23 (an antagonist for CIRP-TLR4) at late stage of sepsis. RNA-seq was conducted to reveal the pivotal molecular mechanism of CIRP on Treg/Th17 differentiation. Naïve CD4+ T cell was isolated from the Tlr4 null and wildtype mice in the presence or absence rmCIRP and C23 to confirmed above findings.

RESULTS

A total of 19 patients with sepsis finally completed the study. Serum CIRP levels remained high in the majority of patients up to 1 week after admittance was closely associated with high Treg/Th17 ratio of peripheral blood and poor outcome. A univariate logistic analysis demonstrated that higher CIRP concentration at Day 7 is an independent risk factor for Treg/Th17 ratio increasing. CIRP promotes Treg development and suppresses Th17 differentiation was found both in vivo and in vitro. Pretreated with C23 not only alleviated the majority of negative effect of CIRP on Th17 differentiation, but also inhibited Treg differentiation, to some extent. Tlr4 deficiency could abolish almost all downstream effects of rmCIRP. Furthermore, IL-2 is proved a key downstream molecules of the effect CIRP, which also could amplify the activated CD4+ T lymphocytes.

CONCLUSIONS

Persistent high circulating CIRP level may lead to Treg/Th17 ratio elevated through TLR4 and subsequent active IL-2 signaling which contribute to immunosuppression during late phases of sepsis.

Revitalizing antitumor immunity: Leveraging nucleic acid sensors as therapeutic targets

Nucleic acid sensors play a critical role in recognizing and responding to pathogenic nucleic acids as danger signals. Upon activation, these sensors initiate downstream signaling cascades that lead to the production and release of pro-inflammatory cytokines, chemokines, and type I interferons. These immune mediators orchestrate diverse effector responses, including the activation of immune cells and the modulation of the tumor microenvironment. However, careful consideration must be given to balancing the activation of nucleic acid sensors to avoid unwanted autoimmune or inflammatory responses. In this review, we provide an overview of nucleic acid sensors and their role in combating cancer through the perception of various aberrant nucleic acids and activation of the immune system. We discuss the connections between different programmed cell death modes and nucleic acid sensors. Finally, we outline the development of nucleic acid sensor agonists, highlighting how their potential as therapeutic targets opens up new avenues for cancer immunotherapy.

ACE2-dependent and -independent SARS-CoV-2 entries dictate viral replication and inflammatory response during infection

Excessive inflammation is the primary cause of mortality in patients with severe COVID-19, yet the underlying mechanisms remain poorly understood. Our study reveals that ACE2-dependent and -independent entries of SARS-CoV-2 in epithelial cells versus myeloid cells dictate viral replication and inflammatory responses. Mechanistically, SARS-CoV-2 NSP14 potently enhances NF-κB signalling by promoting IKK phosphorylation, while SARS-CoV-2 ORF6 exerts an opposing effect. In epithelial cells, ACE2-dependent SARS-CoV-2 entry enables viral replication, with translated ORF6 suppressing NF-κB signalling. In contrast, in myeloid cells, ACE2-independent entry blocks the translation of ORF6 and other viral structural proteins due to inefficient subgenomic RNA transcription, but NSP14 could be directly translated from genomic RNA, resulting in an abortive replication but hyperactivation of the NF-κB signalling pathway for proinflammatory cytokine production. Importantly, we identified TLR1 as a critical factor responsible for viral entry and subsequent inflammatory response through interaction with E and M proteins, which could be blocked by the small-molecule inhibitor Cu-CPT22. Collectively, our findings provide molecular insights into the mechanisms by which strong viral replication but scarce inflammatory response during the early (ACE2-dependent) infection stage, followed by low viral replication and potent inflammatory response in the late (ACE2-independent) infection stage, may contribute to COVID-19 progression.

Toll-like receptor signalling as a cannabinoid target

Toll-like receptors (TLRs) have become a focus in biomedicine and biomedical research given the roles of this unique family of innate immune proteins in immune activation, infection, and autoimmunity. It is evident that TLR dysregulation, and subsequent alterations in TLR-mediated inflammatory signalling, can contribute to disease pathogenesis, and TLR targeted therapies are in development. This review highlights evidence that cannabinoids are key regulators of TLR signalling. Cannabinoids include component of the plant Cannabis sativa L. (C. sativa), synthetic and endogenous ligands, and overall represent a class of compounds whose therapeutic potential and mechanism of action continues to be elucidated. Cannabinoid-based medicines are in the clinic, and are furthermore under intense investigation for broad clinical development to manage symptoms of a range of disorders. In this review, we present an overview of research evidence that signalling linked to a range of TLRs is targeted by cannabinoids, and such cannabinoid mediated effects represent therapeutic avenues for further investigation. First, we provide an overview of TLRs, adaptors and key signalling events, alongside a summary of evidence that TLRs are linked to disease pathologies. Next, we discuss the cannabinoids system and the development of cannabinoid-based therapeutics. Finally, for the bulk of this review, we systematically outline the evidence that cannabinoids (plant-derived cannabinoids, synthetic cannabinoids, and endogenous cannabinoid ligands) can cross-talk with innate immune signalling governed by TLRs, focusing specifically on each member of the TLR family. Cannabinoids should be considered as key regulators of signalling controlled by TLRs, and such regulation should be a major focus in terms of the anti-inflammatory propensity of the cannabinoid system.

Harnessing innate immune pathways for therapeutic advancement in cancer

The innate immune pathway is receiving increasing attention in cancer therapy. This pathway is ubiquitous across various cell types, not only in innate immune cells but also in adaptive immune cells, tumor cells, and stromal cells. Agonists targeting the innate immune pathway have shown profound changes in the tumor microenvironment (TME) and improved tumor prognosis in preclinical studies. However, to date, the clinical success of drugs targeting the innate immune pathway remains limited. Interestingly, recent studies have shown that activation of the innate immune pathway can paradoxically promote tumor progression. The uncertainty surrounding the therapeutic effectiveness of targeted drugs for the innate immune pathway is a critical issue that needs immediate investigation. In this review, we observe that the role of the innate immune pathway demonstrates heterogeneity, linked to the tumor development stage, pathway status, and specific cell types. We propose that within the TME, the innate immune pathway exhibits multidimensional diversity. This diversity is fundamentally rooted in cellular heterogeneity and is manifested as a variety of signaling networks. The pro-tumor effect of innate immune pathway activation essentially reflects the suppression of classical pathways and the activation of potential pro-tumor alternative pathways. Refining our understanding of the tumor's innate immune pathway network and employing appropriate targeting strategies can enhance our ability to harness the anti-tumor potential of the innate immune pathway and ultimately bridge the gap from preclinical to clinical application.

Recent advances in different interactions between toll-like receptors and hepatitis B infection: a review

Hepatitis B virus (HBV) B infections remain a primary global health concern. The immunopathology of the infection, specifically the interactions between HBV and the host immune system, remains somewhat unknown. It has been discovered that innate immune reactions are vital in eliminating HBV. Toll-like receptors (TLRs) are an essential category of proteins that detect pathogen-associated molecular patterns (PAMPs). They begin pathways of intracellular signals to stimulate pro-inflammatory and anti-inflammatory cytokines, thus forming adaptive immune reactions. HBV TLRs include TLR2, TLR3, TLR4, TLR7 and TLR9. Each TLR has its particular molecule to recognize; various TLRs impact HBV and play distinct roles in the pathogenesis of the disease. TLR gene polymorphisms may have an advantageous or disadvantageous efficacy on HBV infection, and some single nucleotide polymorphisms (SNPs) can influence the progression or prognosis of infection. Additionally, it has been discovered that similar SNPs in TLR genes might have varied effects on distinct populations due to stress, diet, and external physical variables. In addition, activation of TLR-interceded signaling pathways could suppress HBV replication and increase HBV-particular T-cell and B-cell reactions. By identifying these associated polymorphisms, we can efficiently advance the immune efficacy of vaccines. Additionally, this will enhance our capability to forecast the danger of HBV infection or the threat of dependent liver disease development via several TLR SNPs, thus playing a role in the inhibition, monitoring, and even treatment guidance for HBV infection. This review will show TLR polymorphisms, their influence on TLR signaling, and their associations with HBV diseases.

Metabolic reprogramming of immune cells by mitochondrial division inhibitor-1 to prevent post-vascular injury neointimal hyperplasia

BACKGROUND AND AIMS

New treatments are needed to prevent neointimal hyperplasia that contributes to post-angioplasty and stent restenosis in patients with coronary artery disease (CAD) and peripheral arterial disease (PAD). We investigated whether modulating mitochondrial function using mitochondrial division inhibitor-1 (Mdivi-1) could reduce post-vascular injury neointimal hyperplasia by metabolic reprogramming of macrophages from a pro-inflammatory to anti-inflammatory phenotype.

METHODS AND RESULTS

In vivo Mdivi-1 treatment of Apoe-/- mice fed a high-fat diet and subjected to carotid-wire injury decreased neointimal hyperplasia by 68%, reduced numbers of plaque vascular smooth muscle cells and pro-inflammatory M1-like macrophages, and decreased plaque inflammation, endothelial activation, and apoptosis, when compared to control. Mdivi-1 treatment of human THP-1 macrophages shifted polarization from a pro-inflammatory M1-like to an anti-inflammatory M2-like phenotype, reduced monocyte chemotaxis and migration to CCL2 and macrophage colony stimulating factor (M-CSF) and decreased secretion of pro-inflammatory mediators. Finally, treatment of pro-inflammatory M1-type-macrophages with Mdivi-1 metabolically reprogrammed them to an anti-inflammatory M2-like phenotype by inhibiting oxidative phosphorylation and attenuating the increase in succinate levels and correcting the decreased levels of arginine and citrulline.

CONCLUSIONS

We report that treatment with Mdivi-1 inhibits post-vascular injury neointimal hyperplasia by metabolic reprogramming macrophages towards an anti-inflammatory phenotype thereby highlighting the therapeutic potential of Mdivi-1 for preventing neointimal hyperplasia and restenosis following angioplasty and stenting in CAD and PAD patients.

Leukemia cells accumulate zinc for oncofusion protein stabilization

Acute promyelocytic leukemia (APL) and chronic myeloid leukemia (CML) are both hematological malignancies characterized by genetic alterations leading to the formation of oncofusion proteins. The classical chromosomal aberrations in APL and CML result in the PML-RARα and BCR-ABL1 oncofusion proteins, respectively. Interestingly, our flow cytometric analyses revealed elevated free intracellular zinc levels in various leukemia cells, which may play a role in stabilizing oncofusion proteins in leukemia and thus support cell proliferation and malignancy. Long-term zinc deficiency resulted in the degradation of PML-RARα in NB4 cells (APL cell line) and of BCR-ABL1 in K562 cells (CML cell line). This degradation may be explained by increased caspase 3 activity observed in zinc deficient cells, whereas zinc reconstitution normalized the caspase 3 activity and abolished zinc deficiency-induced oncofusion protein degradation. In NB4 cells, fluorescence microscopic images further indicated enlarged and enriched lysosomes during zinc deficiency, suggesting increased rates of autophagy. Moreover, NB4 cells exhibited increased expression of the zinc transporters ZIP2, ZIP10 and ZnT3 during zinc deficiency and revealed excessive accumulation of zinc in contrast to healthy peripheral blood mononuclear cells (PBMCs), when zinc was abundantly available extracellularly. Our results highlight the importance of altered zinc homeostasis for some characteristics in leukemia cells, uncover potential pathways underlying the effects of zinc deficiency in leukemia cells, and provide potential alternative strategies by which oncofusion proteins can be degraded.

Harnessing the innate immune system by revolutionizing macrophage-mediated cancer immunotherapy

Immunotherapy is a promising and safer alternative to conventional cancer therapies. It involves adaptive T-cell therapy, cancer vaccines, monoclonal antibodies, immune checkpoint blockade (ICB), and chimeric antigen receptor (CAR) based therapies. However, most of these modalities encounter restrictions in solid tumours owing to a dense, highly hypoxic and immune-suppressive microenvironment as well as the heterogeneity of tumour antigens. The elevated intra-tumoural pressure and mutational rates within fastgrowing solid tumours present challenges in efficient drug targeting and delivery. The tumour microenvironment is a dynamic niche infiltrated by a variety of immune cells, most of which are macrophages. Since they form a part of the innate immune system, targeting macrophages has become a plausible immunotherapeutic approach. In this review, we discuss several versatile approaches (both at pre-clinical and clinical stages) such as the direct killing of tumour-associated macrophages, reprogramming pro-tumour macrophages to anti-tumour phenotypes, inhibition of macrophage recruitment into the tumour microenvironment, novel CAR macrophages, and genetically engineered macrophages that have been devised thus far. These strategies comprise a strong and adaptable macrophage-toolkit in the ongoing fight against cancer and by understanding their significance, we may unlock the full potential of these immune cells in cancer therapy.

Acute Kidney Injury: Definition, Management, and Promising Therapeutic Target

Acute kidney injury (AKI) is caused by a sudden loss of renal function, resulting in the build-up of waste products and a significant increase in mortality and morbidity. It is commonly diagnosed in critically ill patients, with its occurrence estimated at up to 50% in patients hospitalized in the intensive critical unit. Despite ongoing efforts, the death rate associated with AKI has remained high over the past half-century. Thus, it is critical to investigate novel therapy options for preventing the epidemic. Many studies have found that inflammation and Toll-like receptor-4 (TLR-4) activation have a significant role in the pathogenesis of AKI. Noteworthy, challenges in the search for efficient pharmacological therapy for AKI have arisen due to the multifaceted origin and complexity of the clinical history of people with the disease. This article focuses on kidney injury's epidemiology, risk factors, and pathophysiological processes. Specifically, it focuses on the role of TLRs especially type 4 in disease development.

Innate immune regulations and various siRNA modalities

RNAi therapeutics are designed to produce the precise silencing effects against the gene-linked diseases which were known to be untreatable in the past. The highly immunostimulatory nature of siRNA enhances the off-target effects and easily get attacked by nucleases; hence, their modulation is essentially required for accurate alterations to be made in the structures to intensify the pharmacological attributes. The phosphonate modifications act as shield against undue phosphorylation effects, and the molecular changes in ribose sugar lowers the level of immunogenicity and increases the binding efficacy. When bases are substituted with virtual/or pseudo bases, they eventually reduce the off-target effects. These changes modulate the nucleic acid sensors and control the hyper-activation of innate immune response. Various modification designs based on STC (universal pattern), ESC, ESC + (advanced patterns) and disubstrate have been explored to silence the gene expression of various diseases e.g., hepatitis, HIV, influenza, RSV, CNV and acute kidney injury. This review describes the various innovative siRNA therapeutics and their implications on the developed immune regulations to silence the disease effects. siRNA causes the silencing effects through RISC processing. The innate immune signalling is induced by both TLR-dependent and TLR-independent pathways. Modification chemistries are utilized to modulate the immune response.

cGAS-STING Pathway Activation during Trypanosoma cruzi Infection Leads to Tissue-Dependent Parasite Control

Host cell invasion by Trypanosoma cruzi is a markedly silent process, with limited host transcriptional changes indicative of innate immune recognition, except for a modest type I IFN (IFN-I) response. In this study, we show that T. cruzi-induced IFN-β production was nearly abolished in primary murine cGAS-/- or stimulator of IFN genes (STING)-deficient (STINGGt) macrophages and fibroblasts. T. cruzi infection did not impact the ability of IFN-regulatory factor reporter macrophages to respond to classical cGAS-STING agonists, indicating that the limited IFN-β induction is not due to active parasite suppression. cGAS-/-, STINGGt, and IFN-α/β receptor-/- (IFNAR-/-) macrophages infected with T. cruzi yielded significantly higher numbers of amastigotes compared with wild-type macrophages; however, the impact of the STING pathway during infection in vivo is more complex. Despite an initial increase in parasite growth, STINGGt and IFNAR-/- mice ultimately had lower parasite burden in footpads as compared with wild-type mice, demonstrating a role for IFN-I expression in potentiating parasite growth at the infection site. STING pathway activation had little impact on parasite levels in the skeletal muscle; however, in the heart, cGAS-/- and STINGGt mice, but not IFNAR-/- mice, accumulated higher acute parasite loads, suggesting a protective role of STING sensing of T. cruzi in this organ that was independent of IFN-I. Together, these results demonstrate that host cGAS-STING senses T. cruzi infection, enhancing parasite growth at the site of entry, and contributes to acute-phase parasite restriction in the heart, a major site of tissue damage in chronic T. cruzi infection.

Striped Expression of Leucine-Rich Repeat Proteins Coordinates Cell Intercalation and Compartment Boundary Formation in the Early Drosophila Embryo

Planar polarity is a commonly observed phenomenon in which proteins display a consistent asymmetry in their subcellular localization or activity across the plane of a tissue. During animal development, planar polarity is a fundamental mechanism for coordinating the behaviors of groups of cells to achieve anisotropic tissue remodeling, growth, and organization. Therefore, a primary focus of developmental biology research has been to understand the molecular mechanisms underlying planar polarity in a variety of systems to identify conserved principles of tissue organization. In the early Drosophila embryo, the germband neuroectoderm epithelium rapidly doubles in length along the anterior-posterior axis through a process known as convergent extension (CE); it also becomes subdivided into tandem tissue compartments through the formation of compartment boundaries (CBs). Both processes are dependent on the planar polarity of proteins involved in cellular tension and adhesion. The enrichment of actomyosin-based tension and adherens junction-based adhesion at specific cell-cell contacts is required for coordinated cell intercalation, which drives CE, and the creation of highly stable cell-cell contacts at CBs. Recent studies have revealed a system for rapid cellular polarization triggered by the expression of leucine-rich-repeat (LRR) cell-surface proteins in striped patterns. In particular, the non-uniform expression of Toll-2, Toll-6, Toll-8, and Tartan generates local cellular asymmetries that allow cells to distinguish between cell-cell contacts oriented parallel or perpendicular to the anterior-posterior axis. In this review, we discuss (1) the biomechanical underpinnings of CE and CB formation, (2) how the initial symmetry-breaking events of anterior-posterior patterning culminate in planar polarity, and (3) recent advances in understanding the molecular mechanisms downstream of LRR receptors that lead to planar polarized tension and junctional adhesion.

The role of CD180 in hematological malignancies and inflammatory disorders

Toll-like receptors play a significant role in the innate immune system and are also involved in the pathophysiology of many different diseases. Over the past 35 years, there have been a growing number of publications exploring the role of the orphan toll-like receptor, CD180. We therefore set out to provide a narrative review of the current evidence surrounding CD180 in both health and disease. We first explore the evidence surrounding the role of CD180 in physiology including its expression, function and signaling in antigen presenting cells (APCs) (dendritic cells, monocytes, and B cells). We particularly focus on the role of CD180 as a modulator of other TLRs including TLR2, TLR4, and TLR9. We then discuss the role of CD180 in inflammatory and autoimmune diseases, as well as in hematological malignancies of B cell origin, including chronic lymphocytic leukemia (CLL). Based on this evidence we produce a current model for CD180 in disease and explore the potential role for CD180 as both a prognostic biomarker and therapeutic target. Throughout, we highlight specific areas of research which should be addressed to further the understanding of CD180 biology and the translational potential of research into CD180 in various diseases.

The Impacts of Animal-Based Diets in Cardiovascular Disease Development: A Cellular and Physiological Overview

Cardiovascular disease (CVD) is the leading cause of death in the United States, and diet plays an instrumental role in CVD development. Plant-based diets have been strongly tied to a reduction in CVD incidence. In contrast, animal food consumption may increase CVD risk. While increased serum low-density lipoprotein (LDL) cholesterol concentrations are an established risk factor which may partially explain the positive association with animal foods and CVD, numerous other biochemical factors are also at play. Thus, the aim of this review is to summarize the major cellular and molecular effects of animal food consumption in relation to CVD development. Animal-food-centered diets may (1) increase cardiovascular toll-like receptor (TLR) signaling, due to increased serum endotoxins and oxidized LDL cholesterol, (2) increase cardiovascular lipotoxicity, (3) increase renin-angiotensin system components and subsequent angiotensin II type-1 receptor (AT1R) signaling and (4) increase serum trimethylamine-N-oxide concentrations. These nutritionally mediated factors independently increase cardiovascular oxidative stress and inflammation and are all independently tied to CVD development. Public policy efforts should continue to advocate for the consumption of a mostly plant-based diet, with the minimization of animal-based foods.

Evaluation of the tissue repair process and immunomodulatory action of Platelet-Rich Plasma (PRP) in the treatment of abdominal stretch marks

The aims of this study were to characterize and to compare the structural alterations of collagen and elastic fibers in the abdominal stretch marks of patients submitted to intralesional and per quadrant (region close to stretch marks) Platelet-Rich Plasma (PRP) treatment, as well as, to establish the possible mechanisms of action of this treatment involving toll-like receptors (TLRs) signaling pathways and growth factors. Incisional biopsies were collected from abdominal stretch marks with a 2 mm diameter punch in female patients, at the beginning of treatment, after 6 and 12 weeks of treatment, and submitted to morphological analyzes of elastic and collagen fibers, and immunohistochemistry for TLRs signaling pathways and growth factors. Our results demonstrated PRP per quadrant treatment was most effective in reducing the area of the abdominal stretch marks, with consequent stimulation of the synthesis and remodeling of collagen and elastic fibers. Also, PRP per quadrant treatment promoted an increase in TLR2 and TLR4 immunoreactivities, with consequent increase in TNF-α, VEGF and IGF-1. Based on the current findings, PRP constitutes a promising therapeutic approach in patients with stretch marks, since it promoted modulation of inflammatory cytokines and growth factors, with consequent remodeling of extracellular matrix, culminating with tissue improvement.

Characterization analysis of TLR5a and TLR5b immune response after different bacterial infection in grass carp (Ctenopharyngodon idella)

Toll-like receptor (TLR) is an important pattern recognition receptor, which specifically recognizes microbial components, and TLR5 recognizes bacterial flagellin in vertebrates and invertebrates. In this study, two forms of TLR5 (TLR5a and TLR5b) were identified in grass carp (Ctenopharyngodon idella). Aeromonas hydrophila and Staphylococcus aureus were used to investigate the role of grass carp TLR5a and TLR5b against bacteria (flagellate and non-flagellate) in innate immunity, and the expression of TLR5a and TLR5b genes and proteins were detected in immune-related tissues. Quantitative real-time polymerase chain reaction results showed that TLR5a and TLR5b genes of grass carp were highly expressed in the liver, spleen, and head kidney, and their expression patterns were similar in tissues. Meanwhile, the TLR5b gene expression was higher than TLR5a in most tissues. Following exposure to A. hydrophila and S. aureus, the expression levels of TLR5a and TLR5b genes in the liver, spleen, and head kidney were up-regulated significantly. Moreover, the downstream gene, NF-κB, was up-regulated significantly. After A. hydrophila infection, the expression of TLR5a gene was up-regulated in the liver and spleen at 24 h, while TLR5b was up-regulated at 6 h. In the head kidney, TLR5a was up-regulated at 6 h, while TLR5b was up-regulated at 6 h and 12 h. After S. aureus infection, TLR5a and TLR5b were up-regulated at 6 h in the liver and 12 h in the spleen. However, in the head kidney, TLR5a was down-regulated, while TLR5b was up-regulated. Compared with TLR5a, TLR5b had a higher expression level and stronger response to pathogen stimulation. The immunofluorescence results showed that TLR5a and TLR5b proteins in the liver of grass carp infected with A. hydrophila and S. aureus were similar but different in the spleen and head kidney. The results indicated that TLR5a and TLR5b play a critical role in resisting bacterial infection, and TLR5a and TLR5b had obvious tissue and pathogen specificity. TLR5b may play a major role in immune tissues, while TLR5a may play an auxiliary regulatory role in early infection. In addition, TLR5a and TLR5b have an irreplaceable regulatory role in response to flagellate and non-flagellate bacteria. This lays a foundation to explore further the role of TLR5 in resisting flagellate and non-flagellate infections in fish and provides a reference for the innate immunity research of grass carp.

Regulation of matrix metalloproteinase-9 during monopoiesis and zinc deficiency by chromatin remodeling

INTRODUCTION

Matrix metalloproteinase-9 (MMP-9) cleaves various extracellular matrix proteins, hence significantly contributes to numerous physiological but also pathological processes. Monocytic differentiation is associated with increased MMP-9 gene expression. Interestingly, MMP-9 upregulation during monocytic differentiation is paralleled by a decline in intracellular zinc levels. Hence, an influence of zinc on the regulation of MMP-9 expression may exist. Although, previous studies suggest a vital role of zinc regarding MMP-9 activity, the possible relevance of zinc homeostasis during transcriptional regulation of MMP-9 for example via epigenetic mechanisms is rather unclear.

AIM

This study aims to find a correlation between zinc deficiency and MMP-9 transcriptional regulation, focusing on epigenetics as the possible mechanism behind zinc deficiency-induced changes.

METHODS

The effect of differentiation and zinc deficiency on MMP-9 expression and MMP9 promoter accessibility was investigated using the acute promyelocytic cell line NB4. Intracellular free zinc levels were detected by flow cytometry. MMP-9 gene expression was measured by real-time PCR and ELISA. Analysis of chromatin structures was done using chromatin accessibility by real-time PCR (CHART) assay.

RESULTS

During monocytic differentiation of NB4 cells, the decrease in intracellular zinc levels was paralleled by an increased production of MMP-9. Assessment of chromatin structure revealed increased accessibility of certain regions within the MMP-9 promoter in differentiated cells. Interestingly, upregulated activation-induced MMP-9 gene expression as well as a more accessible MMP-9 promoter were in zinc-deficient NB4 cells whereas zinc resupplementation reversed the effects.

CONCLUSION

These data demonstrate an important role of epigenetic mechanisms in regulating MMP-9 expression under zinc deficiency. This could provide an encouraging step to expand the research on using zinc for the treatment of various pathological conditions such as inflammatory, vascular and autoimmune diseases resulting from MMP-9 deregulation.

Pathogenesis of allergic diseases and implications for therapeutic interventions

Allergic diseases such as allergic rhinitis (AR), allergic asthma (AAS), atopic dermatitis (AD), food allergy (FA), and eczema are systemic diseases caused by an impaired immune system. Accompanied by high recurrence rates, the steadily rising incidence rates of these diseases are attracting increasing attention. The pathogenesis of allergic diseases is complex and involves many factors, including maternal-fetal environment, living environment, genetics, epigenetics, and the body's immune status. The pathogenesis of allergic diseases exhibits a marked heterogeneity, with phenotype and endotype defining visible features and associated molecular mechanisms, respectively. With the rapid development of immunology, molecular biology, and biotechnology, many new biological drugs have been designed for the treatment of allergic diseases, including anti-immunoglobulin E (IgE), anti-interleukin (IL)-5, and anti-thymic stromal lymphopoietin (TSLP)/IL-4, to control symptoms. For doctors and scientists, it is becoming more and more important to understand the influencing factors, pathogenesis, and treatment progress of allergic diseases. This review aimed to assess the epidemiology, pathogenesis, and therapeutic interventions of allergic diseases, including AR, AAS, AD, and FA. We hope to help doctors and scientists understand allergic diseases systematically.

Novel Aspects of the Immune Response Involved in the Peritoneal Damage in Chronic Kidney Disease Patients under Dialysis

Chronic kidney disease (CKD) incidence is growing worldwide, with a significant percentage of CKD patients reaching end-stage renal disease (ESRD) and requiring kidney replacement therapies (KRT). Peritoneal dialysis (PD) is a convenient KRT presenting benefices as home therapy. In PD patients, the peritoneum is chronically exposed to PD fluids containing supraphysiologic concentrations of glucose or other osmotic agents, leading to the activation of cellular and molecular processes of damage, including inflammation and fibrosis. Importantly, peritonitis episodes enhance peritoneum inflammation status and accelerate peritoneal injury. Here, we review the role of immune cells in the damage of the peritoneal membrane (PM) by repeated exposure to PD fluids during KRT as well as by bacterial or viral infections. We also discuss the anti-inflammatory properties of current clinical treatments of CKD patients in KRT and their potential effect on preserving PM integrity. Finally, given the current importance of coronavirus disease 2019 (COVID-19) disease, we also analyze here the implications of this disease in CKD and KRT.

Is it possible to intervene early cirrhosis by targeting toll-like receptors to rebalance the intestinal microbiome?

Cirrhosis is a progressive chronic liver disease caused by one or more causes and characterized by diffuse fibrosis, pseudolobules, and regenerated nodules. Once progression to hepatic decompensation, the function of the liver and other organs is impaired and almost impossible to reverse and recover, which often results in hospitalization, impaired quality of life, and high mortality. However, in the early stage of cirrhosis, there seems to be a possibility of cirrhosis reversal. The development of cirrhosis is related to the intestinal microbiota and activation of toll-like receptors (TLRs) pathways, which could regulate cell proliferation, apoptosis, expression of the hepatomitogen epiregulin, and liver inflammation. Targeting regulation of intestinal microbiota and TLRs pathways could affect the occurrence and development of cirrhosis and its complications. In this paper, we first reviewed the dynamic change of intestinal microbiota and TLRs during cirrhosis progression. And further discussed the interaction between them and potential therapeutic targets to reverse early staged cirrhosis.

Targeting TLR-4 Signaling to Treat COVID-19-induced Acute Kidney Injury

The newly discovered severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) has turned into a potentially fatal pandemic illness. Numerous acute kidney injury (AKI) cases have been reported, although diffuse alveolar destruction and acute respiratory failure are the major symptoms of SARS-CoV-2 infection. The AKI, often known as a sudden loss of kidney function, carries a greater risk of mortality and morbidity. AKI was the second most frequent cause of death after acute respiratory distress syndrome (ARDS) in critically ill patients with coronavirus disease 2019 (COVID-19). While most patients with COVID-19 have moderate symptoms, some have severe symptoms, such as septic shock and ARDS. Also, it has been proven that some patients have severe symptoms, such as the failure of several organs. The kidneys are often affected either directly or indirectly. The major signs of kidney involvement are proteinuria and AKI. It is hypothesized that multiple mechanisms contribute to kidney injury in COVID-19. Direct infection of podocytes and proximal tubular cells in the kidneys may lead to acute tubular necrosis and collapsing glomerulopathy. SARS-CoV2 may also trigger a cascade of immunological responses that lead to AKI, including cytokine storm (CS), macrophage activation syndrome, and Toll-like receptor type-4 activation (TLR-4). Other proposed processes of AKI include interactions between organs, endothelial failure, hypercoagulability, rhabdomyolysis, and sepsis.

Furthermore, ischemic damage to the kidney might result from the decreased oxygen supply. This article focuses on kidney injury’s epidemiology, etiology, and pathophysiological processes. Specifically, it focuses on the CS and the role of TLR-4 in this process. To effectively manage and treat acute kidney damage and AKI in COVID-19, it is crucial to understand the underlying molecular pathways and pathophysiology.

Soy Lecithin in High-Fat Diets Exerts Dual Effects on Adipose Tissue Versus Ileum

SCOPE

Lipopolysaccharides and their transporters, LBP and sCD14, are involved in systemic inflammation following a high-fat diet. Natural emulsifiers such as soy lecithin, rich in soybean polar lipids (SPL), are often used by the food industry but little is known about effects of associating SPL with different oils.

METHODS AND RESULTS

Thus, this study investigates the effects of 4 weeks feeding of palm (P) or rapeseed (R) oil-enriched diets with or without SPL in mice, on white adipose tissue (WAT) inflammation, on ileum permeability, and on microbiota composition. When SPL are associated with rapeseed oil, a greater gene expression of leptin and inflammation in WAT is observed compared to P-SPL. In ileum, R-SPL group results in a lower expression of TLR4, IAP that detoxify bacterial LPS and tight junction proteins than R group. In turn, the gene expression of Reg3β and Reg3γ, which have antimicrobial activity, is higher in ileum of R-SPL group than in R group. SPL in rapeseed oil increases specific bacterial species belonging to Lachnospiraceae, Alistipes, and Bacteroidales.

CONCLUSION

The incorporation of SPL in a diet with rapeseed oil exerts differential effect on WAT and ileum, with respectively an inflammation of WAT and an antimicrobial activity in ileum, associated with specific microbiota changes.

The Role of TRL7/8 Agonists in Cancer Therapy, with Special Emphasis on Hematologic Malignancies

Toll-like receptors (TLR) belong to the pattern recognition receptors (PRR). TLR7 and the closely correlated TLR8 affiliate with toll-like receptors family, are located in endosomes. They recognize single-stranded ribonucleic acid (RNA) molecules and synthetic deoxyribonucleic acid (DNA)/RNA analogs-oligoribonucleotides. TLRs are primarily expressed in hematopoietic cells. There is compiling evidence implying that TLRs also direct the formation of blood cellular components and make a contribution to the pathogenesis of certain hematopoietic malignancies. The latest research shows a positive effect of therapy with TRL agonists on the course of hemato-oncological diseases. Ligands impact activation of antigen-presenting cells which results in production of cytokines, transfer of mentioned cells to the lymphoid tissue and co-stimulatory surface molecules expression required for T-cell activation. Toll-like receptor agonists have already been used in oncology especially in the treatment of dermatological neoplastic lesions. The usage of these substances in the treatment of solid tumors is being investigated. The present review discusses the direct and indirect influence that TLR7/8 agonists, such as imiquimod, imidazoquinolines and resiquimod have on neoplastic cells and their promising role as adjuvants in anticancer vaccines.

IL-32 is induced by activation of toll-like receptors in multiple myeloma cells

Multiple myeloma (MM) is a hematological cancer characterized by accumulation of malignant plasma cells in the bone marrow. The patients are immune suppressed and suffer from recurrent and chronic infections. Interleukin-32 is a non-conventional, pro-inflammatory cytokine expressed in a subgroup of MM patients with a poor prognosis. IL-32 has also been shown to promote proliferation and survival of the cancer cells. Here we show that activation of toll-like receptors (TLRs) promotes expression of IL-32 in MM cells through NFκB activation. In patient-derived primary MM cells, IL-32 expression is positively associated with expression of TLRs. Furthermore, we found that several TLR genes are upregulated from diagnosis to relapse in individual patients, predominantly TLRs sensing bacterial components. Interestingly, upregulation of these TLRs coincides with an increase in IL-32. Taken together, these results support a role for IL-32 in microbial sensing in MM cells and suggest that infections can induce expression of this pro-tumorigenic cytokine in MM patients.

The novel anti-cancer feature of Brazzein through activating of hTLR5 by integration of biological evaluation: molecular docking and molecular dynamics simulation

Many of plant proteins exhibit the properties similar to the antitumor proteins although the anticancer activity of Brazzein on modulating the autophagy signaling pathway has not been determined so far. The present study aimed to develop a simplified system to enable the rational design of the activating extracellular domain of human Toll-like receptor 5 (hTLR5). To identify the anticancer effect of Brazzein, HADDOCK program and molecular dynamics (MD) simulation were applied to examine the binding of the wild type (WT) and p.A19K mutant of Brazzein to the TLR5. The expression of MAP1S and TNF-α genes was estimated based on real-time PCR. The results clearly confirmed that the WT of Brazzein activated hTLR5 in the MCF-7 cell line since the genes were more and significantly less expressed in the cells treated with the WT and p.A19K mutant than the control, respectively. The snapshots of MD simulation exhibit the consistent close interactions of hTLR5 with the two helices of Brazzein on its lateral side. The results of per residue-free energy decomposition analysis substantiate those of intermolecular contact analysis perfectly one. We propose that the WT of Brazzein can act as an antitumor drug candidate.

Toll-like receptor-targeted anti-tumor therapies: Advances and challenges

Toll-like receptors (TLRs) are pattern recognition receptors, originally discovered to stimulate innate immune reactions against microbial infection. TLRs also play essential roles in bridging the innate and adaptive immune system, playing multiple roles in inflammation, autoimmune diseases, and cancer. Thanks to the immune stimulatory potential of TLRs, TLR-targeted strategies in cancer treatment have proved to be able to regulate the tumor microenvironment towards tumoricidal phenotypes. Quantities of pre-clinical studies and clinical trials using TLR-targeted strategies in treating cancer have been initiated, with some drugs already becoming part of standard care. Here we review the structure, ligand, signaling pathways, and expression of TLRs; we then provide an overview of the pre-clinical studies and an updated clinical trial watch targeting each TLR in cancer treatment; and finally, we discuss the challenges and prospects of TLR-targeted therapy.

TLR9 signalling activation via direct ligation and its functional consequences in CD4 + T cells

CpG Oligodeoxynucleotides (ODNs) are established TLR9 ligands; however, their functional responses in CD4+ T cells are believed to be independent of TLR9 and MyD88. We studied ligand-receptor interactions of ODN 2216 and TLR9 in human CD4+ T cells and assessed their consequences in terms of TLR9 signalling and cell phenotype. We demonstrated that the uptake of ODN 2216, a synthetic TLR9 agonist, is controlled by TLR9 signalling molecules and results in an increase in the expression of TLR9 signalling molecules, regulated via a feedback mechanism. Next, the uptake of ODN 2216 resulted in TLR9 signalling dependent but MyD88 independent increase in expression of TGF-β. Finally, ODN 2216 treated CD4+ T cells showed an anti-inflammatory phenotype that was similar to Th3 type of regulatory T cells. These Th3-like cells were able to suppress the proliferation of untreated CD4+ T cells. Collectively, our results demonstrate a direct and interdependent relationship between ODN 2216 uptake and TLR9 signalling in CD4+ T cells. Our findings thus pave the way for future research to explore direct modulation of adaptive immune cells, using innate immune ligands, to subvert exaggerated inflammatory responses.

Lacticaseibacillus casei Strain Shirota Modulates Macrophage-Intestinal Epithelial Cell Co-Culture Barrier Integrity, Bacterial Sensing and Inflammatory Cytokines

Probiotic bacteria modulate macrophage immune inflammatory responses, with functional cytokine responses determined by macrophage subset polarisation, stimulation and probiotic strain. Mucosal macrophages exhibit subset functional heterogeneity but are organised in a 3-dimensional tissue, over-laid by barrier epithelial cells. This study aimed to investigate the effects of the probiotic Lacticaseibacillus casei strain Shirota (LcS) on macrophage-epithelial cell cytokine responses, pattern recognition receptor (PRR) expression and LPS responses and the impacts on barrier integrity. THP-1-derived M1 and M2 subset macrophages were co-cultured in a transwell system with differentiated Caco-2 epithelial cells in the presence or absence of enteropathogenic LPS. Both Caco-2 cells in monoculture and macrophage co-culture were assayed for cytokines, PRR expression and barrier integrity (TEER and ZO-1) by RT-PCR, ELISA, IHC and electrical resistance. Caco-2 monocultures expressed distinct cytokine profiles (IL-6, IL-8, TNFα, endogenous IL-10), PRRs and barrier integrity, determined by inflammatory context (TNFα or IL-1β). In co-culture, LcS rescued ZO-1 and TEER in M2/Caco-2, but not M1/Caco-2. LcS suppressed TLR2, TLR4, MD2 expression in both co-cultures and differentially regulated NOD2, TLR9, Tollip and cytokine secretion. In conclusion, LcS selectively modulates epithelial barrier integrity, pathogen sensing and inflammatory cytokine profile; determined by macrophage subset and activation status.

TLR5 Variants Are Associated with the Risk for COPD and NSCLC Development, Better Overall Survival of the NSCLC Patients and Increased Chemosensitivity in the H1299 Cell Line

Chronic obstructive pulmonary disease (COPD) is considered as the strongest independent risk factor for lung cancer (LC) development, suggesting an overlapping genetic background in both diseases. A common feature of both diseases is aberrant immunity in respiratory epithelia that is mainly regulated by Toll-like receptors (TLRs), key regulators of innate immunity. The function of the flagellin-sensing TLR5 in airway epithelia and pathophysiology of COPD and LC has remained elusive. We performed case−control genetic association and functional studies on the importance of TLR5 in COPD and LC development, comparing Caucasian COPD/LC patients (n = 974) and healthy donors (n = 1283). Association analysis of three single nucleotide polymorphisms (SNPs) (rs725084, rs2072493_N592S, and rs5744174_F616L) indicated the minor allele of rs2072493_N592S to be associated with increased risk for COPD (OR = 4.41, p < 0.0001) and NSCLC (OR = 5.17, p < 0.0001) development and non-small cell LC risk in the presence of COPD (OR = 1.75, p = 0.0031). The presence of minor alleles (rs5744174 and rs725084) in a co-dominant model was associated with overall survival in squamous cell LC patients. Functional analysis indicated that overexpression of the rs2072493_N592S allele affected the activation of NF-κB and AP-1, which could be attributed to impaired phosphorylation of p38 and ERK. Overexpression of TLR5N592S was associated with increased chemosensitivity in the H1299 cell line. Finally, genome-wide transcriptomic analysis on WI-38 and H1299 cells overexpressing TLR5WT or TLR5N592S, respectively, indicated the existence of different transcription profiles affecting several cellular pathways potentially associated with a dysregulated immune response. Our results suggest that TLR5 could be recognized as a potential biomarker for COPD and LC development with functional relevance.

Inhibition of human macrophage activation via pregnane neurosteroid interactions with toll-like receptors: Sex differences and structural requirements

We recently discovered that (3α,5α)3-hydroxypregnan-20-one (allopregnanolone) inhibits pro-inflammatory toll-like receptor (TLR) activation and cytokine/chemokine production in mouse macrophage RAW264.7 cells. The present studies evaluate neurosteroid actions upon TLR activation in human macrophages from male and female healthy donors. Buffy coat leukocytes were obtained from donors at the New York Blood Center (http://nybloodcenter.org/), and peripheral blood mononuclear cells were isolated and cultured to achieve macrophage differentiation. TLR4 and TLR7 were activated by lipopolysaccharide (LPS) or imiquimod in the presence/absence of allopregnanolone or related neurosteroids and pro-inflammatory markers were detected by ELISA or western blotting. Cultured human monocyte-derived-macrophages exhibited typical morphology, a mixed immune profile of both inflammatory and anti-inflammatory markers, with no sex difference at baseline. Allopregnanolone inhibited TLR4 activation in male and female donors, preventing LPS-induced elevations of TNF-α, MCP-1, pCREB and pSTAT1. In contrast, 3α,5α-THDOC and SGE-516 inhibited the TLR4 pathway activation in female, but not male donors. Allopregnanolone completely inhibited TLR7 activation by imiquimod, blocking IL-1-β, IL-6, pSTAT1 and pIRF7 elevations in females only. 3α,5α-THDOC and SGE-516 partially inhibited TLR7 activation, only in female donors. The results indicate that allopregnanolone inhibits TLR4 and TLR7 activation in cultured human macrophages resulting in diminished cytokine/chemokine production. Allopregnanolone inhibition of TLR4 activation was found in males and females, but inhibition of TLR7 signals exhibited specificity for female donors. 3α,5α-THDOC and SGE-516 inhibited TLR4 and TLR7 pathways only in females. These studies demonstrate anti-inflammatory effects of allopregnanolone in human macrophages for the first time and suggest that inhibition of pro-inflammatory cytokines/chemokines may contribute to its therapeutic actions.

Adjuvant Discovery via a High Throughput Screen using Human Primary Mononuclear Cells

Motivation

Vaccines are a key biomedical intervention to prevent the spread of infectious diseases, but their efficacy can be limited by insufficient immunogenicity and nonuniform reactogenic profiles. Adjuvants are molecules that potentiate vaccine responses by inducing innate immune activation. However, there are a limited number of adjuvants in approved vaccines, and current approaches for preclinical adjuvant discovery and development are inefficient. To enhance adjuvant identification, we developed a protocol based on in vitro screening of human primary leukocytes.

Summary

We describe a methodology utilizing high-throughput and high-content screening for novel adjuvant candidates that was used to screen a library of ~2,500 small molecules via a 384-well quantitative combined cytokine and flow cytometry immunoassay in primary human peripheral blood mononuclear cells (PBMCs) from 4 healthy adult study participants. Hits were identified based on their induction of soluble cytokine (TNF, IFNg and IL-10) secretion and PBMC maturation (CD 80/86, Ox40, and HLA-DR) in at least two of the four donors screened. From an initial set of 197 compounds identified using these biomarkers-an 8.6% hit rate-we downselected to five scaffolds that demonstrated robust efficacy and potency in vitro and evaluated the top hit, vinblastine sulfate, for adjuvanticity in vivo. Vinblastine sulfate significantly enhanced murine humoral responses to recombinant SARS-CoV-2 spike protein, including a four-fold enhancement of IgG titer production when compared to treatment with the spike antigen alone. Overall, we outline a methodology for discovering immunomodulators with adjuvant potential via high-throughput screening of PBMCs in vitro that yielded a lead compound with in vivo adjuvanticity.

Inhibition of TLR4 Suppresses the Inflammatory Response in Inflammatory Bowel Disease (IBD) by Modulating the PDK1-Induced Metabolism Reprogramming via a m6A-Denpendent Manner

Objective

To investigate the role of TLR4 and PDK1 genes in IBD.

Methods

The DSS mouse model was established by inducing BALB/C with 5% DSS solution. The behavior of DSS mice was detected, and the m6A modification was detected by m6A methylation chip. At the same time, the expressions of TLR and PDK1 were detected by fluorescence real-time quantitative PCR.

Results

The results showed that the model of dextran sodium sulfate colitis in mice was successful, and the colon membrane of mice had obvious naked eye inflammation. Through comparison, it was found that there were differences in m6A modification between the blank group and the model group, and compared with the blank group, the expression of PKD1 in DSS group was significantly reduced and the expression of TLR4 was significantly increased.

Conclusion

TLR4 inhibition inhibits the inflammatory response in inflammatory bowel disease (IBD) in a m6A-dependent manner by regulating PDK1-induced metabolic reprogramming.

Toll-like receptor (TLR) agonists as a driving force behind next-generation vaccine adjuvants and cancer therapeutics

Until recently, the development of new human adjuvants was held back by a poor understanding of their mechanisms of action. The field was revolutionized by the discovery of the toll-like receptors (TLRs), innate immune receptors that directly or indirectly are responsible for detecting pathogen-associated molecular patterns (PAMPs) and respond to them by activating innate and adaptive immune pathways. Hundreds of ligands targeting various TLRs have since been identified and characterized as vaccine adjuvants. This work has important implications not only for the development of vaccines against infectious diseases but also for immuno-therapies against cancer, allergy, Alzheimer's disease, drug addiction and other diseases. Each TLR has its own specific tissue localization and downstream gene signalling pathways, providing researchers the opportunity to precisely tailor adjuvants with specific immune effects. TLR agonists can be combined with other TLR or alternative adjuvants to create combination adjuvants with synergistic or modulatory effects. This review provides an introduction to the various classes of TLR adjuvants and their respective signalling pathways. It provides an overview of recent advancements in the TLR field in the past 2-3 years and discusses criteria for selecting specific TLR adjuvants based on considerations, such as disease mechanisms and correlates of protection, TLR immune biasing capabilities, route of administration, antigen compatibility, new vaccine technology platforms, and age- and species-specific effects.

Intestinal serotonergic system is modulated by Toll-like receptor 9

Intestinal serotonergic system is a key modulator of intestinal homeostasis; however, its regulation is still unclear. Toll-like receptor 9 (TLR9), an innate immune receptor, detects different external agents in the intestine, preserving intestinal integrity. Since little is known about TLR9 role in the intestine, our aim was to address the potential regulation between TLR9 and intestinal serotonergic system. Caco-2/TC7 cell line and intestinal tract of Tlr9^−/− mice were used in this study. Serotonin uptake studies were performed, and molecular expression of different serotonergic components was analyzed by western blot and real-time PCR. Our results show that TLR9 activation inhibits serotonin transporter activity and expression, involving p38/MAPK and ERK/MAPK intracellular pathways, and reciprocally, serotonin increases TLR9 expression. Supporting this interaction, serotonin transporter, serotonin receptors and serotonin producer enzymes were found altered in intestinal tract of Tlr9^−/− mice. We conclude that TLR9 could contribute to intestinal homeostasis by modulation of intestinal serotonergic system.

Toll-like receptor and cytokine expression throughout the bone marrow differs between patients with low- and high-risk myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are hematopoietic stem cell disorders, the pathogenesis of which involves enhanced immune signaling that promotes or selects for mutant hematopoietic stem and progenitor cells (HSPCs). In particular, toll-like receptor (TLR) expression and signaling are enhanced in MDS, and their inhibition is an attractive therapeutic strategy. Although prior studies have reported increased expression of TLR2 and its binding partners TLR1 and TLR6 in the CD34+ cells of patients with MDS (especially those with low-risk disease), TLR expression in other cell types throughout the bone marrow is largely unknown. To address this, we used mass cytometry to assess the expression of TLR1, TLR2, and TLR6 and cytokines in the bone marrow hematopoietic cells of six low/intermediate-risk and six high-risk unmatched MDS bone marrow samples, as well as healthy controls, both at baseline and in response to TLR agonists. We observed several consistent differences between the groups. Most notably, TLR expression was upregulated in multiple cell populations in the low/intermediate-risk, but not high-risk, patients. In addition, many cytokines, including interleukin-6, interleukin-8, tumor necrosis factor α, transforming growth factor β, macrophage inflammatory protein 1β, and granzyme B, were highly expressed from various cell types in low/intermediate-risk patients. However, these same cytokines, with the exception of transforming growth factor β, were expressed at lower levels in high-risk MDS. Together, these findings highlight the differential role of inflammation, and specifically TLR expression, in low/intermediate- versus high-risk MDS, and suggest that elevated TLR expression and cytokine production in multiple cell types likely influences the pathogenesis of MDS in lower-risk patients.

Induced CAR-Macrophages as a Novel Therapeutic Cell Type for Cancer Immune Cell Therapies

The Chimeric antigen receptor (CAR)-T cell therapy has made inroads in treating hematological malignancies. Nonetheless, there are still multiple hurdles in CAR-T cell therapy for solid tumors. Primary CAR-expressing macrophage cells (CAR-Ms) and induced pluripotent stem cells (iPSCs)-derived CAR-expressing macrophage cells (CAR-iMacs) have emerged as attractive alternatives in our quest for an efficient and inexpensive approach for tumor immune cell therapy. In this review, we list the current state of development of human CAR-macrophages and provide an overview of the crucial functions of human CAR-macrophages in the field of tumor immune cell therapy.

Differential susceptibility to lipopolysaccharide affects the activation of toll-like-receptor 4 signaling in THP-1 cells and PMA-differentiated THP-1 cells

Monocytes and macrophages that originate from common myeloid progenitors perform various crucial roles in the innate immune system. Stimulation with LPS combined with TLR4 drives the production of pro-inflammatory cytokines through MAPKs and NF-κB pathway in different cells. However, the difference in LPS susceptibility between monocytes and macrophages is poorly understood. In this study, we found that pro-inflammatory cytokines-IL-1β, IL-6 and TNFα showed greater induction in phorbol-12-myristate-13-acetate (PMA)-differentiated THP-1 cells than in THP-1 cells. To determine the difference in cytokine expression, the surface proteins such as TLR4-related proteins and intracellular adaptor proteins were more preserved in PMA-differentiated THP-1 cells than in THP-1 cells. MyD88 is a key molecule responsible for the difference in LPS susceptibility. Moreover, MAPKs and NF-κB pathway-related molecules showed higher levels of phosphorylation in PMA-differentiated THP-1 cells than in THP-1 cells. Upon MyD88 depletion, there was no difference in the phosphorylation of MAPK pathway-related molecules. Therefore, these results demonstrate that the difference in LPS susceptibility between THP-1 cells and PMA-differentiated THP-1 cells occur as a result of gap between the activated MAPKs and NF-κB pathways via changes in the expression of LPS-related receptors and MyD88.

Modeling Innate Antiviral Immunity in Physiological Context

An effective innate antiviral response is critical for the mitigation of severe disease and host survival following infection. In vivo, the innate antiviral response is triggered by cells that detect the invading pathogen and then communicate through autocrine and paracrine signaling to stimulate the expression of genes that inhibit viral replication, curtail cell proliferation, or modulate the immune response. In other words, the innate antiviral response is complex and dynamic. Notably, in the laboratory, culturing viruses and assaying viral life cycles frequently utilizes cells that are derived from tissues other than those that support viral replication during natural infection, while the study of viral pathogenesis often employs animal models. In recapitulating the human antiviral response, it is important to consider that variation in the expression and function of innate immune sensors and antiviral effectors exists across species, cell types, and cell differentiation states, as well as when cells are placed in different contexts. Thus, to gain novel insight into the dynamics of the host response and how specific sensors and effectors impact infection kinetics by a particular virus, the model system must be selected carefully. In this review, we briefly introduce key signaling pathways involved in the innate antiviral response and highlight how these differ between systems. We then review the application of tissue-engineered or 3D models for studying the antiviral response, and suggest how these in vitro culture systems could be further utilized to assay physiologically-relevant host responses and reveal novel insight into virus-host interactions.

DnaJ-induced TLR7 mediates an increase in interferons through the TLR4-engaged AKT/NF-κB and JNK signaling pathways in macrophages

Toll-like receptor 7 (TLR7) signaling plays pivotal roles in innate immunity by sensing viral single-stranded RNA thereby triggering inflammatory signaling cascades and eliciting protective antiviral responses. In this study, we found that TLR7 expression is highly induced in response to Pseudomonas aeruginosa (P. aeruginosa) infection in a dose- and time-dependent manner. P. aeruginosa-derived DnaJ, a homolog of HSP40, was identified as a related inducing agent for TLR7 expression, and expression of DnaJ was stimulated when host cells were infected with P. aeruginosa. Interestingly, DnaJ was not involved in mediating an increase in the expression levels of TLR3 and TLR8, other well-known antiviral receptors. The induction of TLR7 in response to DnaJ was mediated by the activation of the AKT (Thr308 and Ser473)/NF-κB and p38/JNK MAPKs signaling pathways, consequently transmitting related signals for the expression of interferons (IFNs). Of note, these antiviral responses were regulated, at least in part, by TLR4, which senses the presence of DnaJ and then promotes downstream activation of the AKT (Ser473)/NF-κB and JNK signaling cascades. Taken together, these results suggest that P. aeruginosa-derived DnaJ is sufficient to promote an increase in TLR7 expression in the TLR4-engaged AKT/NF-κB and JNK signaling pathways, thereby promoting an increased antiviral response through the elevated expression of IFNs.

Recent Advances in the Development of Toll-like Receptor Agonist-Based Vaccine Adjuvants for Infectious Diseases

Vaccines are powerful tools for controlling microbial infections and preventing epidemic diseases. Efficient inactive, subunit, or viral-like particle vaccines usually rely on a safe and potent adjuvant to boost the immune response to the antigen. After a slow start, over the last decade there has been increased developments on adjuvants for human vaccines. The development of adjuvants has paralleled our increased understanding of the molecular mechanisms for the pattern recognition receptor (PRR)-mediated activation of immune responses. Toll-like receptors (TLRs) are a group of PRRs that recognize microbial pathogens to initiate a host’s response to infection. Activation of TLRs triggers potent and immediate innate immune responses, which leads to subsequent adaptive immune responses. Therefore, these TLRs are ideal targets for the development of effective adjuvants. To date, TLR agonists such as monophosphoryl lipid A (MPL) and CpG-1018 have been formulated in licensed vaccines for their adjuvant activity, and other TLR agonists are being developed for this purpose. The COVID-19 pandemic has also accelerated clinical research of vaccines containing TLR agonist-based adjuvants. In this paper, we reviewed the agonists for TLR activation and the molecular mechanisms associated with the adjuvants’ effects on TLR activation, emphasizing recent advances in the development of TLR agonist-based vaccine adjuvants for infectious diseases.