Toll-like receptors' two-edged sword: when immunity meets apoptosis

Participation of TLRs in cancer immunopathogenesis and drug resistance via interacting with immunological and/or non-immunological signaling pathways as well as lncRNAs

Toll-like receptors (TLRs) have a convoluted role in cancer even though they are crucial to the immune system. By bridging the innate immune system and cancer, TLRs have a very complex impact on the formation of tumors and the effectiveness of anti-cancer treatments. TLR signaling links the innate and adaptive immune systems and initiates direct pathogen eradication. In cancer immunopathogenesis and treatment resistance, long non-coding RNAs (lncRNAs) modify TLR signaling linkages with immunological and non-immunological pathways. We identified lncRNAs that positively and negatively control TLR signaling, impacting immunological response and drug sensitivity. These results highlight the complex interactions between long non-coding RNAs and TLRs that influence the start of cancer and its response to treatment. Targeting specific lncRNAs is a practical way to control TLR signaling and perhaps enhance anti-tumor immunity while overcoming medication resistance. We provide a framework for developing novel immunotherapeutic regimens and customized medicine approaches for cancer treatment. The exact mechanisms by which lncRNAs regulate TLR signaling pathways should be defined by further research, and these findings should be validated in clinical situations. This finding makes future research of lncRNA-based drugs in combination with existing cancer treatments feasible.

Immune response of Rhinogobio ventralis to Ichthyophthirius multifiliis infection: Insights from histopathological and real-time gene expression analyses

Ichthyophthirius multifiliis is a parasite that poses a considerable threat to aquaculture and the ornamental fish industry, but with limited effective treatment options available. This study employed RT-qPCR to detect and analyze the expression changes of partial toll-like receptor (TLR) genes (TLR1 and TLR21), adapter protein and signal transduction molecule genes (MyD88, TRIF, NF-κB, IRAK4, and IRF3), and cytokines (IL-6, IL-8, IL-13, CXC-α and CXCR1), as well as complement C3, in the skin, gill, fin, liver, head kidney and spleen of Rhinogobio ventralis under different infection conditions. Additionally, tissue sections and scanning electron microscopy were utilized to observe the pathological changes in the gills and fins of R. ventralis after infection with I. multifiliis. The expression patterns of TLR-related DEGs (differentially expressed genes) in diseased wild fish were analyzed, revealing upregulation of TLR1, TLR21, MyD88, NF-κB, IRAK4, TRIF, IRF3, IL-6, IL-8, IL-13, CXC-α, CXCR1, and C3 genes in various tissues, indicating that these genes may be involved in the immune response of R. ventralis to I. multifiliis infection. To further analyze the gene expression of sampled from the field, an artificial infection model of R. ventralis was established under laboratory conditions, with additional sampling from the skin and fins. These genes continued to show varying degrees of upregulation, but the results were not entirely consistent with those from Wudongde samples, which may be due to the more complex environment in the wild or differences in the degree of I. multifiliis infection in wild fish. The infection of I. multifiliis caused severe damage to the gills and fins of R. ventralis, characterized by extensive secretions on the gill and fin surfaces, with the presence of attached I. multifiliis trophonts, including damage and loss of gill filaments, swollen gill lamellae, and deformed gill plates, as well as cell proliferation and necrosis of gill epithelial cells. This study sheds light on the role of the TLR signaling pathway in resisting I. multifiliis infection and its associated histopathological changes in R. ventralis, providing valuable insights for the prevention and treatment of I. multifiliis infection in R. ventralis.

Elevated toll-like receptor 9 is associated with disease severity and kidney involvement in systemic lupus erythematosus

OBJECTIVES

Systemic lupus erythematosus (SLE) is associated with the activation of both innate and adaptive immune system. Infection is a significant environmental factor that is responsible for the development of SLE. Toll-like receptors (TLRs) are responsible for recognizing pathogens, and the expression of TLRs has been found to differ in SLE patients. Additionally, various infections have been reported to influence TLR expression. This study aimed to explore the relationship between TLRs and the onset, severity, and symptoms of SLE in the eastern Indian population.

METHODS

The study included 70 SLE patients and a control group matched for age and sex. RT-PCR was used to evaluate mRNA expression of TLRs 2, 4, 7, and 9. Statistical analyses were performed using GraphPad Prism software v.10.2.3.

RESULTS

Patients with SLE expressed significantly higher levels of TLR2 (p < 0.0001) and TLR9 (p = 0.012) than healthy controls. In lupus nephritis, TLR9 expression was higher than in SLE patients without kidney involvement (p = 0.037). Furthermore, a significant relationship was found between TLR9 expression and systemic lupus erythematosus disease activity index (SLEDAI) scores (p < 0.0001, Spearman's r = 0.47), implying the potential role of TLRs in SLE development. However, mRNA expression of TLR4 and TLR7 was not associated with SLE, clinical indices, or disease severity.

CONCLUSIONS

TLR9 is associated with SLE pathogenesis and clinical severity, making it a promising molecule for targeted therapy in SLE management.

Special Issue "The Role of Toll-Like Receptors (TLRs) in Infection and Inflammation 2.0"

Toll-like receptors (TLRs) are key players in the innate immune system, in host' first-line defense against pathogens [...].

In Vitro Transcribed mRNA Immunogenicity Induces Chemokine-Mediated Lymphocyte Recruitment and Can Be Gradually Tailored by Uridine Modification

Beyond SARS-CoV2 vaccines, mRNA drugs are being explored to overcome today's greatest healthcare burdens, including cancer and cardiovascular disease. Synthetic mRNA triggers immune responses in transfected cells, which can be reduced by chemically modified nucleotides. However, the side effects of mRNA-triggered immune activation on cell function and how different nucleotides, such as the N1-methylpseudouridine (m1Ψ) used in SARS-CoV2 vaccines, can modulate cellular responses is not fully understood. Here, cellular responses toward a library of uridine-modified mRNAs are investigated in primary human cells. Targeted proteomics analyses reveal that unmodified mRNA induces a pro-inflammatory paracrine pattern marked by the secretion of chemokines, which recruit T and B lymphocytes toward transfected cells. Importantly, the magnitude of mRNA-induced changes in cell function varies quantitatively between unmodified, Ψ-, m1Ψ-, and 5moU-modified mRNA and can be gradually tailored, with implications for deliberately exploiting this effect in mRNA drug design. Indeed, both the immunosuppressive effect of stromal cells on T-cell proliferation, and the anti-inflammatory effect of IL-10 mRNA are enhanced by appropriate uridine modification. The results provide new insights into the effects of mRNA drugs on cell function and cell-cell communication and open new possibilities to tailor mRNA-triggered immune activation to the desired pro- or anti-inflammatory application.

Validation and application of caged Z-DEVD-aminoluciferin bioluminescence for assessment of apoptosis of wild type and TLR2-deficient mice after ischemic stroke

Programmed cell death or apoptosis is a critically important mechanism of tissue remodeling and regulates conditions such as cancer, neurodegeneration or stroke. The aim of this research article was to assess the caged Z-DEVD-aminoluciferin substrate for in vivo monitoring of apoptosis after ischemic stroke in TLR2-deficient mice and their TLR2-expressing counterparts. Postischemic inflammation is a significant contributor to ischemic injury development and apoptosis, and it is modified by the TLR2 receptor. Caged Z-DEVD-aminoluciferin is made available for bioluminescence enzymatic reaction by cleavage with activated caspase-3, and therefore it is assumed to be capable of reporting and measuring apoptosis. Apoptosis was investigated for 28 days after stroke in mice which ubiquitously expressed the firefly luciferase transgene. Middle cerebral artery occlusion was performed to achieve ischemic injury, which was followed with magnetic resonance imaging. The scope of apoptosis was determined by bioluminescence with caged Z-DEVD-aminoluciferin, immunofluorescence with activated caspase-3, flow cytometry with annexin-V and TUNEL assay. The linearity of Z-DEVD-aminoluciferin substrate dose effect was shown in the murine brain. Z-DEVD-aminoluciferin was validated as a good tool for monitoring apoptosis following adequate adjustment. By utilizing bioluminescence of Z-DEVD-aminoluciferin after ischemic stroke it was shown that TLR2-deficient mice had lower post-stroke apoptosis than TLR2-expressing wild type mice. In conclusion, Z-DEVD-aminoluciferin could be a valuable tool for apoptosis measurement in living mice.

TLR agonists as vaccine adjuvants in the prevention of viral infections: an overview

Tol-like receptor (TLR) agonists, as potent adjuvants, have gained attention in vaccine research for their ability to enhance immune responses. This study focuses on their application in improving vaccine efficacy against key viral infections, including hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), SARS-CoV-2, influenza virus, and flaviviruses, including West Nile virus, dengue virus, and chikungunya virus. Vaccines are crucial in preventing microbial infections, including viruses, and adjuvants play a vital role in modulating immune responses. However, there are still many diseases for which effective vaccines are lacking or have limited immune response, posing significant threats to human health. The use of TLR agonists as adjuvants in viral vaccine formulations holds promise in improving vaccine effectiveness. By tailoring adjuvants to specific pathogens, such as HBV, HCV, HIV, SARS-CoV-2, influenza virus, and flavivirus, protective immunity against chronic and emerging infectious disease can be elicited.

Transcriptome-based analysis of human peripheral blood reveals regulators of immune response in different viral infections

Introduction

There are difficulties in creating direct antiviral drugs for all viruses, including new, suddenly arising infections, such as COVID-19. Therefore, pathogenesis-directed therapy is often necessary to treat severe viral infections and comorbidities associated with them. Despite significant differences in the etiopathogenesis of viral diseases, in general, they are associated with significant dysfunction of the immune system. Study of common mechanisms of immune dysfunction caused by different viral infections can help develop novel therapeutic strategies to combat infections and associated comorbidities.

Methods

To identify common mechanisms of immune functions disruption during infection by nine different viruses (cytomegalovirus, Ebstein-Barr virus, human T-cell leukemia virus type 1, Hepatitis B and C viruses, human immunodeficiency virus, Dengue virus, SARS-CoV, and SARS-CoV-2), we analyzed the corresponding transcription profiles from peripheral blood mononuclear cells (PBMC) using the originally developed pipeline that include transcriptome data collection, processing, normalization, analysis and search for master regulators of several viral infections. The ten datasets containing transcription data from patients infected by nine viruses and healthy people were obtained from Gene Expression Omnibus. The analysis of the data was performed by Genome Enhancer pipeline.

Results

We revealed common pathways, cellular processes, and master regulators for studied viral infections. We found that all nine viral infections cause immune activation, exhaustion, cell proliferation disruption, and increased susceptibility to apoptosis. Using network analysis, we identified PBMC receptors, representing proteins at the top of signaling pathways that may be responsible for the observed transcriptional changes and maintain the current functional state of cells.

Discussion

The identified relationships between some of them and virus-induced alteration of immune functions are new and have not been found earlier, e.g., receptors for autocrine motility factor, insulin, prolactin, angiotensin II, and immunoglobulin epsilon. Modulation of the identified receptors can be investigated as one of therapeutic strategies for the treatment of severe viral infections.

Terpenes: Modulating anti-inflammatory signaling in inflammatory bowel disease

Inflammatory Bowel Disease (IBD) are autoimmune diseases characterized by chronic intestinal inflammation. Considered a western disease, IBD incidence in newly developed countries is skyrocketing. Accordingly, global prevalence is steadily increasing. There are two major IBD phenotypes, ulcerative colitis (UC) and Crohn's disease (CD). UC manifests as uninterrupted inflammation localized in the colon and rectum. Meanwhile, CD presents as interrupted inflammation that can occur throughout the digestive tract. As a result, therapeutics have focused on anti-inflammatory approaches for its treatment. Unfortunately, only 50% of patients benefit from current Food and Drug Administration approved treatments, and all are associated with serious adverse effects. Thus, there is a need for safer and novel therapeutics to increase the efficacy in this population. One aspect that is critical in understanding IBD is how food and phytochemicals therein may be associated with modifying the pathogenesis of IBD. A variety of retrospective and prospective studies, and clinical trials have shown benefits of plant-rich diets on the prevention and symptomatic improvement of IBD. The Mediterranean diet is rich in vegetables, fruits, legumes, and herbs; and characterized by the abundance of anti-inflammatory phytochemicals. An understudied phytochemical class enriched in this diet is terpenes; isoprene-based molecules are widely available in Mediterranean herbs and citrus fruits. Various terpenes have been evaluated in different IBD models. However, some present contradictory or inconclusive results. Therefore, in this review we evaluated preclinical studies of terpenes modulating basic inflammatory signaling related to IBD.

The Molecular Basis and Clinical Consequences of Chronic Inflammation in Prostatic Diseases: Prostatitis, Benign Prostatic Hyperplasia, and Prostate Cancer

Chronic inflammation is now recognized as one of the major risk factors and molecular hallmarks of chronic prostatitis, benign prostatic hyperplasia (BPH), and prostate tumorigenesis. However, the molecular mechanisms by which chronic inflammation signaling contributes to the pathogenesis of these prostate diseases are poorly understood. Previous efforts to therapeutically target the upstream (e.g., TLRs and IL1-Rs) and downstream (e.g., NF-κB subunits and cytokines) inflammatory signaling molecules in people with these conditions have been clinically ambiguous and unsatisfactory, hence fostering the recent paradigm shift towards unraveling and understanding the functional roles and clinical significance of the novel and relatively underexplored inflammatory molecules and pathways that could become potential therapeutic targets in managing prostatic diseases. In this review article, we exclusively discuss the causal and molecular drivers of prostatitis, BPH, and prostate tumorigenesis, as well as the potential impacts of microbiome dysbiosis and chronic inflammation in promoting prostate pathologies. We specifically focus on the importance of some of the underexplored druggable inflammatory molecules, by discussing how their aberrant signaling could promote prostate cancer (PCa) stemness, neuroendocrine differentiation, castration resistance, metabolic reprogramming, and immunosuppression. The potential contribution of the IL1R-TLR-IRAK-NF-κBs signaling molecules and NLR/inflammasomes in prostate pathologies, as well as the prospective benefits of selectively targeting the midstream molecules in the various inflammatory cascades, are also discussed. Though this review concentrates more on PCa, we envision that the information could be applied to other prostate diseases. In conclusion, we have underlined the molecular mechanisms and signaling pathways that may need to be targeted and/or further investigated to better understand the association between chronic inflammation and prostate diseases.

Characterization of TLR1 and expression profiling of TLR signaling pathway related genes in response to Aeromonas hydrophila challenge in hybrid yellow catfish (Pelteobagrus fulvidraco ♀ × P. vachelli ♂)

Toll‐like receptor 1 (TLR1) mediates the innate immune response to a variety of microbes through recognizing cell wall components (such as bacterial lipoproteins) in mammals. However, the detailed molecular mechanism of TLR1 involved in pathogen immunity in the representative hybrid yellow catfish (Pelteobagrus fulvidraco ♀ × P. vachelli ♂) has not been well studied. In the present study, we identified the TLR1 gene from the hybrid yellow catfish, and further comparative synteny data from multiple species confirmed that the TLR1 gene is highly conserved in teleosts. Phylogenetic analysis revealed distinguishable TLR1s in diverse taxa, suggesting consistence in evolution of the TLR1 proteins with various species. Structural prediction indicated that the three-dimensional structures of TLR1 proteins are relatively conserved among different taxa. Positive selection analysis showed that purifying selection dominated the evolutionary process of TLR1s and TLR1-TIR domain in both vertebrates and invertebrates. Expression pattern analysis based on the tissue distribution showed that TLR1 mainly transcribed in the gonad, gallbladder and kidney, and the mRNA levels of TLR1 in kidney were remarkably up-regulated after Aeromonas hydrophila stimulation, indicating that TLR1 participates in the inflammatory responses to exogenous pathogen infection in hybrid yellow catfish. Homologous sequence alignment and chromosomal location indicated that the TLR signaling pathway is very conserved in the hybrid yellow catfish. The expression patterns of TLR signaling pathway related genes (TLR1- TLR2 - MyD88 - FADD - Caspase 8) were consistent after pathogen stimulation, revealing that the TLR signaling pathway is triggered and activated after A. hydrophila infection. Our findings will lay a solid foundation for better understanding the immune roles of TLR1 in teleosts, as well as provide basic data for developing strategies to control disease outbreak in hybrid yellow catfish.

Nutrigenomic profiling of reduced specification diets and phytogenic inclusion effects on critical TLR signaling, MAPK-apoptosis and PI3K-Akt-mTOR gene components along the broiler gut

The effects of concurrent reduction of dietary metabolizable energy (ME) and crude protein (CP) levels combined or not with the dietary inclusion of a phytogenic feed additive (PFA) were studied using a nutrigenomics approach. In particular, the expression of 26 critical genes relevant for inflammation control (TLR pathway), cellular apoptosis (MAPK pathway) cell growth and nutrient metabolism (PI3K-Akt-mTOR pathway) was profiled along the broiler intestine. Two dietary types (L and H) differing in metabolizable energy and crude protein levels (L: 95% and H: 100% of optimal Cobb 500 recommendations for ME and CP requirements) supplemented or not with PFA (- or +) and their interactions (L-, L+, H-, H+) were evaluated. There were only 3 total interactions (mTOR, IL8, and HRAS P < 0.05) between diet type and PFA inclusion indicating limited concurrent effects. Diet type, L upregulated genes related with inflammation mainly in the jejunum, ileum, and cecum (P < 0.05) and MAPK pathway in the ileum and cecum (P < 0.05). Moreover, diet type L negatively affected the expression of genes related to PI3K-Akt-mTOR pathway mainly in duodenum and cecum (P < 0.05). On the other hand, PFA inclusion downregulated (P < 0.05) genes related with TLR signaling pathway (TLR2B, MyD88, TLR3, IL8, LITAF) along the intestine and MAPK pathway genes (APO1, FOS) in jejunum (P < 0.05). Finally, PFA supplementation regulated nutrient sensing and metabolism in the cecum in a manner perceived as beneficial for growth. In conclusion, the study results highlight that the reduced ME and CP specifications, especially in the absence of PFA, regulate inflammation, apoptosis and nutrient metabolism processes at homeostatic control levels that hinder maximizing the availability of dietary energy and nutrients for growth purposes. Inclusion of PFA helped to adjust the respective homeostatic responses and control to levels supporting broiler performance, especially at reduced specification diets.

Immunomodulatory Effects of Bacterial Toll-like Receptor Ligands on the Phenotype and Function of Milk Immune Cells in Dromedary Camel

(1) Toll-like receptors (TLR) are a family of pattern recognition receptors that sense distinct molecular patterns of microbial origin. Although the immune cell composition of camel milk has been recently described, host-pathogen interaction studies in the camel mammary gland are still scarce. The present study aimed to use a whole milk stimulation assay for investigating the modulatory effect of selected Toll-like receptor (TLR) ligands on the phenotype and function of milk immune cells. (2) Methods-camel milk samples (n = 7) were stimulated in vitro with the TLR4 ligand LPS or the TLR2/1 ligand Pam3CSK4, and separated milk cells were evaluated for stimulation-induced shape change, the expression of cell surface markers, phagocytosis, apoptosis, ROS production, and NETosis. Stimulation with PMA was used as a control stimulation. (3) Results-all stimulants induced shape change in milk cells, change in the expression of several cell markers, and increased cell apoptosis and NETosis. In addition, stimulation with Pam3CSK4 and PMA was associated with enhanced ROS production, while only PMA stimulation resulted in enhanced bacterial phagocytosis by milk immune cells. (4) Conclusions-our data indicates selective modulating effects of the TLR ligands LPS and Pam3CSK4 on camel milk phagocytes. These results may have implications for the use of synthetic TLR agonists as immunomodulatory adjuvants of the immune response to intra-mammary vaccines against mastitis pathogens.

Immune Response of the Monocytic Cell Line THP-1 Against Six Aeromonas spp

Aeromonas are autochthonous bacteria of aquatic environments that are considered to be emerging pathogens to humans, producing diarrhea, bacteremia, and wound infections. Genetic identification shows that 95.4% of the strains associated with clinical cases correspond to the species Aeromonas caviae (37.26%), Aeromonas dhakensis (23.49%), Aeromonas veronii (21.54%), and Aeromonas hydrophila (13.07%). However, few studies have investigated the human immune response against some Aeromonas spp. such as A. hydrophila, Aeromonas salmonicida, and A. veronii. The present study aimed to increase the knowledge about the innate human immune response against six Aeromonas species, using, for the first time, an in vitro infection model with the monocytic human cell line THP-1, and to evaluate the intracellular survival, the cell damage, and the expression of 11 immune-related genes (TLR4, TNF-α, CCL2, CCL20, JUN, RELA, BAX, TP53, CASP3, NLRP3, and IL-1β). Transcriptional analysis showed an upregulated expression of a variety of the monocytic immune-related genes, with a variable response depending upon the Aeromonas species. The species that produced the highest cell damage, independently of the strain origin, coincidentally induced a higher expression of immune-related genes and corresponded to the more prevalent clinical species A. dhakensis, A. veronii, and A. caviae. Additionally, monocytic cells showed an overexpression of the apoptotic and pyroptotic genes involved in cell death after A. dhakensis, A. caviae, and Aeromonas media infection. However, the apoptosis route seemed to be the only way of producing cell damage and death in the case of the species Aeromonas piscicola and Aeromonas jandaei, while A. veronii apparently only used the pyroptosis route.

Understanding the Immune System in Fetal Protection and Maternal Infections during Pregnancy

The fetal-maternal immune system determines the fate of pregnancy. The trophoblast cells not only give an active response against external stimuli but are also involved in secreting most of the cytokines. These cells have an essential function in fetal acceptance or fetal rejection. Other immune cells also play a pivotal role in carrying out a successful pregnancy. The disruption in this mechanism may lead to harmful effects on pregnancy. The placenta serves as an immune barrier in fetus protection against invading pathogens. Once the infections prevail, they may localize in placental and fetal tissues, and the presence of inflammation due to cytokines may have detrimental effects on pregnancy. Moreover, some pathogens are responsible for congenital fetal anomalies and affect almost all organs of the developing fetus. This review article is designed to address the bacterial and viral infections that threaten pregnancy and their possible outcomes. Moreover, training of the fetal immune system against the exposure of infections and the role of CD49a + NK cells in embryonic development will also be highlighted.

Interferon-γ primes macrophages for pathogen ligand-induced killing via a caspase-8 and mitochondrial cell death pathway

Cell death plays an important role during pathogen infections. Here, we report that interferon-γ (IFNγ) sensitizes macrophages to Toll-like receptor (TLR)-induced death that requires macrophage-intrinsic death ligands and caspase-8 enzymatic activity, which trigger the mitochondrial apoptotic effectors, BAX and BAK. The pro-apoptotic caspase-8 substrate BID was dispensable for BAX and BAK activation. Instead, caspase-8 reduced pro-survival BCL-2 transcription and increased inducible nitric oxide synthase (iNOS), thus facilitating BAX and BAK signaling. IFNγ-primed, TLR-induced macrophage killing required iNOS, which licensed apoptotic caspase-8 activity and reduced the BAX and BAK inhibitors, A1 and MCL-1. The deletion of iNOS or caspase-8 limited SARS-CoV-2-induced disease in mice, while caspase-8 caused lethality independent of iNOS in a model of hemophagocytic lymphohistiocytosis. These findings reveal that iNOS selectively licenses programmed cell death, which may explain how nitric oxide impacts disease severity in SARS-CoV-2 infection and other iNOS-associated inflammatory conditions.

The relationship between the efficacy of talazoparib and the functional toll-like receptors 3 and 9 in triple negative breast cancer

Poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi) induce cell death by inhibiting the repair of DNA strand breaks binding to PARP and regulate immune cells functions. Toll-like receptors (TLRs) mediate the tumor microenvironment through the modulation of proinflammatory cytokines and chemokines. In this context, this study addressed the relationship between the efficacy of talazoparib (TAL) as a PARPi and the activation of TLR3 or TLR9 by Polyinosinic:polycytidylic acid (Poly I:C) or CpG oligodeoxynucleotides (CpG-ODN) stimulation, respectively in triple negative breast cancer (TNBC). TAL alone and the combination of TAL with Poly I:C or CpG-ODN induced cell death were analyzed by water-soluble tetrazolium salt 1 (WST-1), Annexin V analysis, acridine orange staining and mRNA levels of caspase-3 and caspase-8 in HCC1937 and HCC1937-R (TAL resistant) TNBC cells. Additionally, the expression of TLR3, TLR9 and interferon regulatory factor 7 (IRF7) was observed with immunofluorescence staining and western blot analysis. Our findings showed that TAL induced TLR3 and TLR9 activation and acted in synergy with TLR3 and TLR9 agonists in TNBC cells. The stimulation of TLR3 or TLR9 and TAL treatment caused significantly more apoptosis in TNBC cells through the over-expression of caspase-3 and caspase-8. Additionally, TAL combined with Poly I:C or CpG-ODN more increased TLR3, TLR9 and IRF7 protein levels in HCC1937 cells and treatment with TAL and Poly I:C had greater potential for overcoming TAL resistance. In conclusion, the combination of PARPi with TLR agonists may be a new therapeutic combined strategy for the effective immunotherapy of TNBC.

An Overview of Recent Insights into the Response of TLR to SARS-CoV-2 Infection and the Potential of TLR Agonists as SARS-CoV-2 Vaccine Adjuvants

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to coronavirus disease (COVID-19), a global health pandemic causing millions of deaths worldwide. However, the immunopathogenesis of COVID-19, particularly the interaction between SARS-CoV-2 and host innate immunity, remains unclear. The innate immune system acts as the first line of host defense, which is critical for the initial detection of invading pathogens and the activation and shaping of adaptive immunity. Toll-like receptors (TLRs) are key sensors of innate immunity that recognize pathogen-associated molecular patterns and activate downstream signaling for pro-inflammatory cytokine and chemokine production. However, TLRs may also act as a double-edged sword, and dysregulated TLR responses may enhance immune-mediated pathology, instead of providing protection. Therefore, a proper understanding of the interaction between TLRs and SARS-CoV-2 is of great importance for devising therapeutic and preventive strategies. The use of TLR agonists as vaccine adjuvants for human disease is a promising approach that could be applied in the investigation of COVID-19 vaccines. In this review, we discuss the recent progress in our understanding of host innate immune responses in SARS-CoV-2 infection, with particular focus on TLR response. In addition, we discuss the use of TLR agonists as vaccine adjuvants in enhancing the efficacy of COVID-19 vaccine.

Mesenchymal stromal cell apoptosis is required for their therapeutic function

Multipotent mesenchymal stromal cells (MSCs) ameliorate a wide range of diseases in preclinical models, but the lack of clarity around their mechanisms of action has impeded their clinical utility. The therapeutic effects of MSCs are often attributed to bioactive molecules secreted by viable MSCs. However, we found that MSCs underwent apoptosis in the lung after intravenous administration, even in the absence of host cytotoxic or alloreactive cells. Deletion of the apoptotic effectors BAK and BAX prevented MSC death and attenuated their immunosuppressive effects in disease models used to define MSC potency. Mechanistically, apoptosis of MSCs and their efferocytosis induced changes in metabolic and inflammatory pathways in alveolar macrophages to effect immunosuppression and reduce disease severity. Our data reveal a mode of action whereby the host response to dying MSCs is key to their therapeutic effects; findings that have broad implications for the effective translation of cell-based therapies.

Mesenchymal stromal cells (MSCs) demonstrate therapeutic benefits in multiple diseases, but the mechanisms remain unclear as infused MSCs do not persist in the body. Here, the authors show that MSC apoptosis is an important mechanistic element, as MSCs rendered genetically incapable of apoptosis lose their ability to ameliorate disease.

Proteomic profiles of Zika virus-infected placentas bearing fetuses with microcephaly

PURPOSE

Zika virus (ZIKV) transmission to the fetus during pregnancy could enable a collection of severe fetal malformations like microcephaly (MC), termed Congenital Zika Syndrome (CZS). The mechanisms involved in ZIKV transplacental transmission are not fully understood.

EXPERIMENTAL DESIGN

Here we aim to identify in placental tissues the deregulated proteins associated with ZIKV-induced MC using label-free proteomics.

RESULTS

We found proteins associated with DNA damage and gene expression inhibition up-regulated in infected placentas with no MC fetuses (Z+) compared to the control group (Ctr). Actin filament organization and the immune response were also found deregulated in the Z+ group. In ZIKV-positive placentas bearing fetuses with MC (MC+) was detected an increase in T cell activation, indicating an elevated immune response. A comparison between MC+ and Z+ groups showed a higher abundance of proteins related to endocytosis and autophagy in MC+, suggesting a higher transcytosis of vesicles with ZIKV particles across the maternal-fetal interface.

CONCLUSIONS AND CLINICAL RELEVANCE

Our results suggest that higher expression of integrins in MC+ might be associated with high internalization of the virus since these proteins are known as virus receptors. Similarly, an increased immune response in the placenta and higher infiltration of the virus to the fetus could contribute to the neurological malformation of the CZS.

Recent Insights Into the Molecular Mechanism of Toll-Like Receptor Response to Dengue Virus Infection

Dengue is the most prevalent and rapidly spreading mosquito-borne viral disease caused by dengue virus (DENV). Recently, DENV has been affecting humans within an expanding geographic range due to the warming of the earth. Innate immune responses play a significant role in antiviral defense, and Toll-like receptors (TLRs) are key regulators of innate immunity. Therefore, a detailed understanding of TLR and DENV interactions is important for devising therapeutic and preventive strategies. Several studies have indicated the ability of DENV to modulate the TLR signaling pathway and host immune response. Vaccination is considered one of the most successful medical interventions for preventing viral infections. However, only a partially protective dengue vaccine, the first licensed dengue vaccine CYD-TDV, is available in some dengue-endemic countries to protect against DENV infection. Therefore, the development of a fully protective, durable, and safe DENV vaccine is a priority for global health. Here, we demonstrate the progress made in our understanding of the host response to DENV infection, with a particular focus on TLR response and how DENV avoids the response toward establishing infection. We also discuss dengue vaccine candidates in late-stage development and the issues that must be overcome to enable their success.

SARS-CoV-2 infection during pregnancy and pregnancy-related conditions: Concerns, challenges, management and mitigation strategies-a narrative review

The ongoing coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a global public health problem. The SARS-CoV-2 triggers hyper-activation of inflammatory and immune responses resulting in cytokine storm and increased inflammatory responses on several organs like lungs, kidneys, intestine, and placenta. Although SARS-CoV-2 affects individuals of all age groups and physiological statuses, immune-compromised individuals such as pregnant women are considered as a highly vulnerable group. This review aims to raise the concerns of high risk of infection, morbidity and mortality of COVID-19 in pregnant women and provides critical reviews of pathophysiology and pathobiology of how SARS-CoV-2 infection potentially increases the severity and fatality during pregnancy. This article also provides a discussion of current evidence on vertical transmission of SARS-CoV-2 during pregnancy and breastfeeding. Lastly, guidelines on management, treatment, preventive, and mitigation strategies of SARS-CoV-2 infection during pregnancy and pregnancy-related conditions such as delivery and breastfeeding are discussed.

Structure-Based Design of Highly Potent Toll-like Receptor 7/8 Dual Agonists for Cancer Immunotherapy

Activation of the toll-like receptors 7 and 8 has emerged as a promising strategy for cancer immunotherapy. Herein, we report the design and synthesis of a series of pyrido[3,2-d]pyrimidine-based toll-like receptor 7/8 dual agonists that exhibited potent and near-equivalent agonistic activities toward TLR7 and TLR8. In vitro, compounds 24e and 25a significantly induced the secretion of IFN-α, IFN-γ, TNF-α, IL-1β, IL-12p40, and IP-10 in human peripheral blood mononuclear cell assays. In vivo, compounds 24e, 24m, and 25a significantly suppressed tumor growth in CT26 tumor-bearing mice by remodeling the tumor microenvironment. Additionally, compounds 24e, 24m, and 25a markedly improved the antitumor activity of PD-1/PD-L1 blockade. In particular, compound 24e combined with the anti-PD-L1 antibody led to complete tumor regression. These results demonstrated that TLR7/8 agonists (24e, 24m, and 25a) held great potential as single agents or in combination with PD-1/PD-L1 blockade for cancer immunotherapy.

Toll-Like Receptor and Cytokine Responses to Infection with Endogenous and Exogenous Koala Retrovirus, and Vaccination as a Control Strategy

Koala populations are currently declining and under threat from koala retrovirus (KoRV) infection both in the wild and in captivity. KoRV is assumed to cause immunosuppression and neoplastic diseases, favoring chlamydiosis in koalas. Currently, 10 KoRV subtypes have been identified, including an endogenous subtype (KoRV-A) and nine exogenous subtypes (KoRV-B to KoRV-J). The host’s immune response acts as a safeguard against pathogens. Therefore, a proper understanding of the immune response mechanisms against infection is of great importance for the host’s survival, as well as for the development of therapeutic and prophylactic interventions. A vaccine is an important protective as well as being a therapeutic tool against infectious disease, and several studies have shown promise for the development of an effective vaccine against KoRV. Moreover, CRISPR/Cas9-based genome editing has opened a new window for gene therapy, and it appears to be a potential therapeutic tool in many viral infections, which could also be investigated for the treatment of KoRV infection. Here, we discuss the recent advances made in the understanding of the immune response in KoRV infection, as well as the progress towards vaccine development against KoRV infection in koalas.

Apoptosis Disorder, a Key Pathogenesis of HCMV-Related Diseases

Human cytomegalovirus (HCMV) belongs to the β-herpesvirus family, which is transmitted in almost every part of the world and is carried by more than 90% of the general population. Increasing evidence indicates that HCMV infection triggers numerous diseases by disrupting the normal physiological activity of host cells, particularly apoptosis. Apoptosis disorder plays a key role in the initiation and development of multiple diseases. However, the relationship and molecular mechanism of HCMV-related diseases and apoptosis have not yet been systematically summarized. This review aims to summarize the role of apoptosis in HCMV-related diseases and provide an insight into the molecular mechanism of apoptosis induced by HCMV infection. We summarize the literature on HCMV-related diseases and suggest novel strategies for HCMV treatment by regulating apoptosis.

Toll-Like Receptor Expression Profiles in Koala (Phascolarctos cinereus) Peripheral Blood Mononuclear Cells Infected with Multiple KoRV Subtypes

Simple Summary

Koala retrovirus (KoRV) is a major pathogen of koala. Toll-like receptors (TLRs) are important innate immune component that are evolutionary conserved and play a crucial role in the early defense against invading pathogens. The expression profile of TLRs in KoRV infection in koalas is not characterized yet. Therefore, in this study, we characterized TLR expression patterns in koalas infected with KoRV-A only vs. KoRV-A with KoRV-B and/or -C. Using qRT-PCR, we measured TLR2–10 and TLR13 mRNA expression in peripheral blood mononuclear cells (PBMCs) and/or tissues from captive koalas in Japanese zoos. We observed variations in TLR expression in koalas with a range of subtype infection profiles (KoRV-A only vs. KoRV-A with KoRV-B and/or -C). The findings of this study might improve our current understanding of koala’s immune response to KoRV infection.

Abstract

Toll-like receptors (TLRs), evolutionarily conserved pattern recognition receptors, play an important role in innate immunity by recognizing microbial pathogen-associated molecular patterns. Koala retrovirus (KoRV), a major koala pathogen, exists in both endogenous (KoRV-A) and exogenous forms (KoRV-B to J). However, the expression profile of TLRs in koalas infected with KoRV-A and other subtypes is yet to characterize. Here, we investigated TLR expression profiles in koalas with a range of subtype infection profiles (KoRV-A only vs. KoRV-A with KoRV-B and/or -C). To this end, we cloned partial sequences for TLRs (TLR2–10 and TLR13), developed real-time PCR assays, and determined TLRs mRNA expression patterns in koala PBMCs and/or tissues. All the reported TLRs for koala were expressed in PBMCs, and variations in TLR expression were observed in koalas infected with exogenous subtypes (KoRV-B and KoRV-C) compared to the endogenous subtype (KoRV-A) only, which indicates the implications of TLRs in KoRV infection. TLRs were also found to be differentially expressed in koala tissues. This is the first report of TLR expression profiles in koala, which provides insights into koala’s immune response to KoRV infection that could be utilized for the future exploitation of TLR modulators in the maintenance of koala health.

TLR3/TICAM-1 signaling in tumor cell RIP3-dependent necroptosis

The engagement of Toll-like receptor 3 (TLR3) leads to the oligomerization of the adaptor TICAM-1 (TRIF), which can induces either of three acute cellular responses, namely, cell survival coupled to Type I interferon production, or cell death, via apoptosis or necrosis. The specific response elicited by TLR3 determines the fate of affected cells, although the switching mechanism between the two cell death pathways in TLR3-stimulated cells remains molecularly unknown. Tumor necrosis factor α (TNFα)-mediated cell death can proceed via apoptosis or via a non-apoptotic pathway, termed necroptosis or programmed necrosis, which have been described in detail. Interestingly, death domain-containing kinases called receptor-interacting protein kinases (RIPs) are involved in the signaling pathways leading to these two cell death pathways. Formation of the RIP1/RIP3 complex (called necrosome) in the absence of caspase 8 activity is crucial for the induction of necroptosis in response to TNFα signaling. On the other hand, RIP1 is known to interact with the C-terminal domain of TICAM-1 and to modulate TLR3 signaling. In macrophages and perhaps tumor cell lines, RIP1/RIP3-mediated necroptotic cell death can ensue the administration of the TLR agonist polyI:C. If this involved the TLR3/TICAM-1 pathway, the innate sensing of viral dsRNA would be linked to cytopathic effects and to persistent inflammation, in turn favoring the release of damage-associated molecular patterns (DAMPs) in the microenvironment. Here, we review accumulating evidence pointing to the involvement of the TLR3/TICAM-1 axis in tumor cell necroptosis and the subsequent release of DAMPs.

Zika virus infection induces endoplasmic reticulum stress and apoptosis in placental trophoblasts

Zika virus (ZIKV) infection to a pregnant woman can be vertically transmitted to the fetus via the placenta leading to Congenital Zika syndrome. This is characterized by microcephaly, retinal defects, and intrauterine growth retardation. ZIKV induces placental trophoblast apoptosis leading to severe abnormalities in the growth and development of the fetus. However, the molecular mechanism behind ZIKV-induced apoptosis in placental trophoblasts remains unclear. We hypothesize that ZIKV infection induces endoplasmic reticulum (ER) stress in the trophoblasts, and sustained ER stress results in apoptosis. HTR-8 (HTR-8/SVneo), a human normal immortalized trophoblast cell and human choriocarcinoma-derived cell lines (JEG-3 and JAR) were infected with ZIKV. Biochemical and structural markers of apoptosis like caspase 3/7 activity and percent apoptotic nuclear morphological changes, respectively were assessed. ZIKV infection in placental trophoblasts showed an increase in the levels of CHOP mRNA and protein expression, which is an inducer of apoptosis. Next, we also observed increased levels of ER stress markers such as phosphorylated forms of inositol-requiring transmembrane kinase/endoribonuclease 1α (P-IRE1α), and its downstream target, the spliced form of XBP1 mRNA, phosphorylated eukaryotic initiation factor 2α (P-eIF2α), and activation of cJun N-terminal Kinase (JNK) and p38 mitogen activated protein kinase (MAPK) after 16-24 h of ZIKV infection in trophoblasts. Inhibition of JNK or pan-caspases using small molecule inhibitors significantly prevented ZIKV-induced apoptosis in trophoblasts. Further, JNK inhibition also reduced XBP1 mRNA splicing and viral E protein staining in ZIKV infected cells. In conclusion, the mechanism of ZIKV-induced placental trophoblast apoptosis involves the activation of ER stress and JNK activation, and the inhibition of JNK dramatically prevents ZIKV-induced trophoblast apoptosis.

Pregnancy Alters Innate and Adaptive Immune Responses to Zika Virus Infection in the Reproductive Tract

Recent outbreaks of Zika virus (ZIKV) have been associated with birth defects, including microcephaly and neurologic impairment. However, the mechanisms that confer potential susceptibility to ZIKV during pregnancy remain unclear. We hypothesized that poor outcomes from ZIKV infection during pregnancy are due in part to pregnancy-induced alteration of innate immune cell frequencies and cytokine expression. To examine the impact of pregnancy on innate immune responses, we inoculated immunocompetent pregnant and nonpregnant female C57BL/6 mice with 5 × 105 focus-forming units of ZIKV intravaginally. Innate immune cell frequencies and cytokine expression were measured by flow cytometry at day 3 postinfection. Compared with nonpregnant mice, pregnant mice exhibited higher frequencies of uterine macrophages (CD68+) and CD11c+ CD103+ and CD11c+ CD11b+ dendritic cells. Additionally, ZIKV-infected pregnant mice had lower frequencies of CD45+ IL-12+ and CD11b+ IL-12+ cells in the uterus and spleen. Next, we measured the frequencies of Ag-experienced CD4 (CD4+ CD11a+ CD49d+) and CD8 (CD8lo CD11ahi) T cells at day 10 postinfection to determine the impact of pregnancy-associated changes in innate cellular IL-12 responses on the adaptive immune response. We found that pregnant mice had lower frequencies of uterine Ag-experienced CD4 T cells and ZIKV-infected pregnant mice had lower frequencies of uterine Ag-experienced CD8 T cells compared with ZIKV-infected nonpregnant mice. These data show that pregnancy results in altered innate and adaptive immune responses to ZIKV infection in the reproductive tract of mice and that pregnancy-associated immune modulation may play an important role in the severity of acute ZIKV infection.

M1 macrophage dependent-p53 regulates the intracellular survival of mycobacteria

Tumor suppressor p53 is not only affects immune responses but also contributes to antibacterial activity. However, its bactericidal function during mycobacterial infection remains unclear. In this study, we found that the p53-deficient macrophages failed to control Mycobacterium tuberculosis (Mtb), manifested as a lower apoptotic cell death rate and enhanced intracellular survival. The expression levels of p53 during Mtb infection were stronger in M1 macrophages than in M2 macrophages. The TLR2/JNK signaling pathway plays an essential role in the modulation of M1 macrophage polarization upon Mtb infection. It facilitates p53-mediated apoptosis through the production of reactive oxygen species, nitric oxide and inflammatory cytokines in Mtb-infected M1 macrophages. In addition, nutlin-3 effectively abrogated the intracellular survival of mycobacteria in both TB patients and healthy controls after H37Ra infection for 24 h, indicating that the enhancement of p53 production effectively suppressed the intracellular survival of Mtb in hosts. These results suggest that p53 can be a new therapeutic target for TB therapy.

Evaluation of the Effects of Nobiletin on Toll-Like Receptor 3 Signaling Pathways in Prostate Cancer In Vitro

Nobiletin as a nontoxic dietary citrus flavonoid has anticancer effects in cancer. Toll-like receptor three has a role in prostate cancer progression. However the relationship among NOB and TLR3 signaling in PCa has not been elucidated, yet. Therefore, we aimed to evaluate the effects of NOB on the activation of TLR3 signaling pathways in PCa In Vitro. PC-3, LNCaP and HUVEC cells were used for comparison of NOB-mediated TLR3 signaling pathways. After treatment with NOB and Poly I:C alone and NOB + Poly I:C, RT-PCR, western blotting and ELISA assay were performed to evaluate changes in gene and protein expression level, as well as CASP8. NOB potentially induced TLR3/IRF3 signaling pathway and the activation of TLR3/IRF3 signaling pathway by both NOB and Poly I:C was more profound in LNCaP than PC-3 cells. However, the level of TRIF protein and CASP8 decreased after both NOB and Poly I:C incubation. NOB could mediate TLR3 signaling pathways. NOB + Poly I:C could improve the activation of TLR3/IRF3 signaling pathway. However, the activation of TRIF/RIPK1/FADD signaling pathway reduced. Therefore, the elucidation of molecular mechanisms of TLR3 signaling pathways and the combination effects of NOB + Poly I:C on apoptotic cell death are further studied.

Insights into the toll-like receptors in sexually transmitted infections

Toll-like receptors (TLRs) are like soldiers of an innate immune system, which protects vital biological processes against invading pathogens. TLR signalling pathways help in the removal of pathogens and mediate well-established inflammatory processes. However, these processes may also aid in the development or augmentation of an infection or an autoimmune disease. Recent studies have delineated TLR polymorphism's role in the loss of function, making hosts more resistant or vulnerable to the development of an infection. In this review, we have discussed the association of TLRs with sexually transmitted infections (STIs), especially to the pathogen-specific ligands. We have also assessed the impact on TLR downstream signalling and the maintenance of cellular homeostasis during immune responses. Besides, we have discussed the role of TLRs single nucleotide polymorphisms in various STIs. Since TLRs are known to play a part in defence mechanisms and in aiding infections therefore, a thorough understanding of TLRs structure and molecular mechanisms is required to explain how they can influence the outcome of an STI. Such a strategy may lead to the development of novel and useful immunotherapeutic approaches to control pathogen progression and prevent transmission.

Analysis of the susceptibility to COVID-19 in pregnancy and recommendations on potential drug screening

To analyze the susceptibility of SARS-CoV-2 in pregnancy and the drugs that can be used to treat pregnancy with COVID-19, so as to provide evidence for drug selection in clinic. By reviewing the existing literature, this paper analyzes the susceptibility of pregnant women to virus, especially to SARS-CoV-2, from the aspects of anatomical, reproductive endocrine and immune changes during pregnancy and screens effective and fetal-safe treatments from the existing drugs. The anatomical structure of the respiratory system is changed during pregnancy, and the virus transmitted by droplets and aerosols is more easily inhaled by pregnant women and is difficult to remove. Furthermore, the prognosis is worse after infection when compared with non-pregnancy women. And changes in reproductive hormones and immune systems during pregnancy collectively make them more susceptible to certain infections. More importantly, angiotensin-converting enzyme (ACE)-2, the SARS-CoV-2 receptor, has been proven highly increased during pregnancy, which may contribute to the susceptibility to SARS-CoV-2. When it comes to treatment, specific drugs for COVID-19 have not been found at present, and taking old drugs for new use in treating COVID-19 has become an emergency method for the pandemic. Particularly, drugs that show superior maternal and fetal safety are worthy of consideration for pregnant women with COVID-19, such as chloroquine, metformin, statins, lobinavir/ritonavir, glycyrrhizic acid, and nanoparticle-mediated drug delivery (NMDD), etc. Pregnant women are susceptible to COVID-19, and special attention should be paid to the selection of drugs that are both effective for maternal diseases and friendly to the fetus. However, there are still many deficiencies in the study of drug safety during pregnancy, and broad-spectrum, effective and fetal-safe drugs for pregnant women need to be developed so as to cope with more infectious diseases in the future.

Biological Considerations in Scaling Up Therapeutic Cell Manufacturing

Cell therapeutics - using cells as living drugs - have made advances in many areas of medicine. One of the most clinically studied cell-based therapy products is mesenchymal stromal cells (MSCs), which have shown promising results in promoting tissue regeneration and modulating inflammation. However, MSC therapy requires large numbers of cells, the generation of which is not feasible via conventional planar tissue culture methods. Scale-up manufacturing methods (e.g., propagation on microcarriers in stirred-tank bioreactors), however, are not specifically tailored for MSC expansion. These processes may, in principle, alter the cell secretome, a vital component underlying the immunosuppressive properties and clinical effectiveness of MSCs. This review outlines our current understanding of MSC properties and immunomodulatory function, expansion in commercial manufacturing systems, and gaps in our knowledge that need to be addressed for effective up-scaling commercialization of MSC therapy.

P53: A Guardian of Immunity Becomes Its Saboteur through Mutation

Awareness of the importance of immunity in controlling cancer development triggered research into the impact of its key oncogenic drivers on the immune response, as well as their value as targets for immunotherapy. At the heart of tumour suppression is p53, which was discovered in the context of viral infection and now emerges as a significant player in normal and cancer immunity. Wild-type p53 (wt p53) plays fundamental roles in cancer immunity and inflammation. Mutations in p53 not only cripple wt p53 immune functions but also sinisterly subvert the immune function through its neomorphic gain-of-functions (GOFs). The prevalence of mutant p53 across different types of human cancers, which are associated with inflammatory and immune dysfunction, further implicates mutant p53 in modulating cancer immunity, thereby promoting tumorigenesis, metastasis and invasion. In this review, we discuss several mutant p53 immune GOFs in the context of the established roles of wt p53 in regulating and responding to tumour-associated inflammation, and regulating innate and adaptive immunity. We discuss the capacity of mutant p53 to alter the tumour milieu to support immune dysfunction, modulate toll-like receptor (TLR) signalling pathways to disrupt innate immunity and subvert cell-mediated immunity in favour of immune privilege and survival. Furthermore, we expose the potential and challenges associated with mutant p53 as a cancer immunotherapy target and underscore existing therapies that may benefit from inquiry into cancer p53 status.

Mechanistic molecular responses of the giant clam Tridacna crocea to Vibrio coralliilyticus challenge

Vibrio coralliilyticus is a pathogen of coral and mollusk, contributing to dramatic losses worldwide. In our study, we found that V. coralliilyticus challenge could directly affect adult Tridacna crocea survival; there were dead individuals appearing at 6 h post infection, and there were 45.56% and 56.78% mortality rates in challenged groups after 36 h of infection. The apoptosis rate of hemocytes was significantly increased by 1.8-fold at 6 h after V. coralliilyticus injection. To shed light on the mechanistic molecular responses of T. crocea to V. coralliilyticus infection, we used transcriptome sequencing analysis and other relevant techniques to analyze T. crocea hemocytes at 0 h, 6 h, 12 h and 24 h after V. coralliilyticus challenge. Our results revealed that the total numbers of unigenes and DEGs were 195651 and 3446, respectively. Additional details were found by KEGG pathway enrichment analysis, where DEGs were significantly enriched in immune-related signaling pathways, such as the TLR signaling pathway, and some were associated with signaling related to apoptosis. Quantitative validation results illustrated that with exposure to V. coralliilyticus, the expression of TLR pathway members, TLR, MyD88, IRAK4, TRAF6, and IкB-α, were significantly upregulated (by 22.9-, 9.6-, 4.0-, 3.6-, and 3.9-fold, respectively) at 6 h. The cytokine-related gene IL-17 exhibited an increase of 6.3-fold and 10.5-fold at 3 h and 6 h, respectively. The apoptosis-related gene IAP1 was dramatically increased by 2.99-fold at 6 h. These results indicate that adult T. crocea could initiate the TLR pathway to resist V. coralliilyticus, which promotes the release of inflammatory factors such as IL-17 and leads to the activation of a series of outcomes, such as apoptosis. The response mechanism is related to the T. crocea immunoreaction stimulated by V. coralliilyticus, providing a theoretical basis for understanding T. crocea immune response mechanisms.

Lumican is upregulated in osteoarthritis and contributes to TLR4-induced pro-inflammatory activation of cartilage degradation and macrophage polarization

OBJECTIVE

Lumican (LUM) is a major extracellular matrix glycoprotein in adult articular cartilage and its expression is known to be upregulated upon cartilage degeneration. LUM is associated with the pathogen-associated molecular pattern (PAMP) activation of the TLR4 signalling cascade, with TLR4 being highly associated with inflammation in rheumatic diseases. However, the main role of the LUM structural molecule in osteoarthritis (OA) remains elusive. The aim of this study was, therefore, to understand the role of LUM during TLR4-mediated activation in OA.

METHODS

After measuring LUM levels in synovial fluid (SF) of OA patients and lipopolysaccharide (LPS)-induced TLR4 activation, the role of LUM in the expression of pro-inflammatory molecules and cartilage degradation was assessed in vitro and ex vivo in a cartilage explant model. Primary macrophage activation and polarization were studied upon LUM co-stimulation with LPS.

RESULTS

We demonstrate that LUM is not only significantly upregulated in SF from OA patients compared to healthy controls, but also that LUM increases lipopolysaccharide (LPS)-induced TLR4 activation. Furthermore, we show that a pathophysiological level of LUM augments the LPS-induced TLR4 activation and expression of downstream pro-inflammatory molecules, resulting in extensive cartilage degradation. LUM co-stimulation with LPS also provided a pro-inflammatory stimulus, upregulating primary macrophage activation and polarization towards the M1-like phenotype.

CONCLUSIONS

These findings strongly support the role of LUM as a mediator of PAMP-induced TLR4 activation of inflammation, cartilage degradation, and macrophage polarization in the OA joint and potentially other rheumatic diseases.

Phycocyanin Exerts Anti-Proliferative Effects through Down-Regulating TIRAP/NF-κB Activity in Human Non-Small Cell Lung Cancer Cells

Phycocyanin is a type of marine functional food additive, exerting a health care efficacy with no side effects. It has been shown that phycocyanin possesses anticancer function in non-small cell lung cancer (NSCLC) cells, but the underlying regulatory mechanism still remains unclear. Further investigation on the antineoplastic mechanism of phycocyanin would provide useful information on NSCLC treatment. In this study, we explored the in vitro function and mechanism of phycocyanin in three typical NSCLC cell lines, H1975, H1650, and LTEP-a2, for the first time. Phenotypic experiments showed that phycocyanin significantly induced the apoptosis as well as suppressed the growth of NSCLC cells. Transcriptome analysis suggested that toll/interleukin 1 receptor domain-containing adaptor protein (TIRAP) was significantly down-regulated by phycocyanin. Strikingly, similar to phycocyanin-treated assays, siRNA knockdown of TIRAP expression also resulted in the anti-proliferative phenomenon in NSCLC cells. In addition, the activity of NF-κB signaling was also suppressed after silencing TIRAP expression, revealing that phycocyanin exerted anti-proliferative function through down-regulating TIRAP/NF-κB activity in NSCLC cells. Collectively, this study has laid a theoretical basis on the treatment of NSCLC and the potential utilization of marine functional products.

Immune responses of fish to Ichthyophthirius multifiliis (Ich): A model for understanding immunity against protozoan parasites

The parasitic ciliate Ichthyophthirius multifiliis (Ich), which infects almost all freshwater fish species, provides an optimal model for the study of immunity against extracellular protozoa. Ich invades the epithelia of mucosal tissues, forms white spots covering the whole body, and induces high mortality, while survivor fish develop both innate and adaptive immunity against Ich attack in systemic and mucosal tissues. Besides the protective roles of the Toll-like receptor (TLR)-mediated innate immune response, the critical immune functions of novel IgT in the skin, gut, gill, and olfactory organ of teleosts have been demonstrated in recent years, and all this information contributes to the ontogeny of the mucosal immune response in vertebrates. Especially in rainbow trout, Ich-infected fish exhibited higher IgT concentrations and titers in the mucosa and increased IgT⁺ B-lymphocyte proliferation in mucosal tissues. IgM mainly functions in the adaptive immune response in the systemic tissues of rainbow trout, accompanied with increased IgM⁺ B-lymphocyte proliferation in the head kidney of Ich-infected trout. However, little is known about the interaction between these mucosal tissues and systemic immune organs and the interaction between the inductive immune organs and functional immune organs. Immobilization antigens (Iags), located on the parasite cell and ciliary membranes, have been characterized to be targeted by specific antibodies produced in the host. The crosslinking of antigens mediated by antibodies triggers either an escape response or the immobilization of Ich. With more knowledge about the Iags of Ich and the immunity of teleosts, a more targeted vaccine, even a DNA vaccine, can be developed for the immune control strategy of Ich. Due to the high frequency of clinical fish ichthyophthiriasis, the study of fish immune responses to Ich provides an optimal experimental model for understanding immunity against extracellular protozoa.

Proteomics and Metabolomics for AKI Diagnosis

Acute kidney injury (AKI) is a severe and frequent condition in hospitalized patients. Currently, no efficient therapy of AKI is available. Therefore, efforts focus on early prevention and potentially early initiation of renal replacement therapy to improve the outcome in AKI. The detection of AKI in hospitalized patients implies the need for early, accurate, robust, and easily accessible biomarkers of AKI evolution and outcome prediction because only a narrow window exists to implement the earlier-described measures. Even more challenging is the multifactorial origin of AKI and the fact that the changes of molecular expression induced by AKI are difficult to distinguish from those of the diseases associated or causing AKI as shock or sepsis. During the past decade, a considerable number of protein biomarkers for AKI have been described and we expect from recent advances in the field of omics technologies that this number will increase further in the future and be extended to other sorts of biomolecules, such as RNAs, lipids, and metabolites. However, most of these biomarkers are poorly defined by their AKI-associated molecular context. In this review, we describe the state-of-the-art tissue and biofluid proteomic and metabolomic technologies and new bioinformatics approaches for proteomic and metabolomic pathway and molecular interaction analysis. In the second part of the review, we focus on AKI-associated proteomic and metabolomic biomarkers and briefly outline their pathophysiological context in AKI.

Pattern Recognition Receptors and the Host Cell Death Molecular Machinery

Pattern Recognition Receptors (PRRs) are proteins capable of recognizing molecules frequently found in pathogens (the so-called Pathogen-Associated Molecular Patterns—PAMPs), or molecules released by damaged cells (the Damage-Associated Molecular Patterns—DAMPs). They emerged phylogenetically prior to the appearance of the adaptive immunity and, therefore, are considered part of the innate immune system. Signals derived from the engagement of PRRs on the immune cells activate microbicidal and pro-inflammatory responses required to eliminate or, at least, to contain infectious agents. Molecularly controlled forms of cell death are also part of a very ancestral mechanism involved in key aspects of the physiology of multicellular organism, including the elimination of unwanted, damaged or infected cells. Interestingly, each form of cell death has its particular effect on inflammation and on the development of innate and adaptive immune responses. In this review article, we discuss some aspects of the molecular interplay between the cell death machinery and signals initiated by the activation of PRRs by PAMPs and DAMPs.

HCMV Infection and Apoptosis: How Do Monocytes Survive HCMV Infection?

Human cytomegalovirus (HCMV) infection of peripheral blood monocytes plays a key role in the hematogenous dissemination of the virus to multiple organ systems following primary infection or reactivation of latent virus in the bone marrow. Monocytes have a short life span of 1⁻3 days in circulation; thus, HCMV must alter their survival and differentiation to utilize these cells and their differentiated counterparts-macrophages-for dissemination and long term viral persistence. Because monocytes are not initially permissive for viral gene expression and replication, HCMV must control host-derived factors early during infection to prevent apoptosis or programmed cell death prior to viral induced differentiation into naturally long-lived macrophages. This review provides a short overview of HCMV infection of monocytes and describes how HCMV has evolved to utilize host cell anti-apoptotic pathways to allow infected monocytes to bridge the 48⁻72 h viability gate so that differentiation into a long term stable mature cell can occur. Because viral gene expression is delayed in monocytes following initial infection and only occurs (begins around two to three weeks post infection in our model) following what appears to be complete differentiation into mature macrophages or dendritic cells, or both; virally-encoded anti-apoptotic gene products cannot initially control long term infected cell survival. Anti-apoptotic viral genes are discussed in the second section of this review and we argue they would play an important role in long term macrophage or dendritic cell survival following infection-induced differentiation.

Extracellular histones activate autophagy and apoptosis via mTOR signaling in human endothelial cells

Circulating histones have been proposed as targets for therapy in sepsis and hyperinflammatory symptoms. However, the proposed strategies have failed in clinical trials. Although different mechanisms for histone-related cytotoxicity are being explored, those mediated by circulating histones are not fully understood. Extracellular histones induce endothelial cell death, thereby contributing to the pathogenesis of complex diseases such as sepsis and septic shock. Therefore, the comprehension of cellular responses triggered by histones is capital to design effective therapeutic strategies. Here we report how extracellular histones induce autophagy and apoptosis in a dose-dependent manner in cultured human endothelial cells. In addition, we describe how histones regulate these pathways via Sestrin2/AMPK/ULK1-mTOR and AKT/mTOR. Furthermore, we evaluate the effect of Toll-like receptors in mediating autophagy and apoptosis demonstrating how TLR inhibitors do not prevent apoptosis and/or autophagy induced by histones. Our results confirm that histones and autophagic pathways can be considered as novel targets to design therapeutic strategies in endothelial damage.

Deoxyelephantopin ameliorates lipopolysaccharides (LPS)-induced memory impairments in rats: Evidence for its anti-neuroinflammatory properties

AIM

Neuroinflammation is a critical pathogenic mechanism of most neurodegenerative disorders especially, Alzheimer's disease (AD). Lipopolysaccharides (LPS) are known to induce neuroinflammation which is evident from significant upsurge of pro-inflammatory mediators in in vitro BV-2 microglial cells and in vivo animal models. In present study, we investigated anti-neuroinflammatory properties of deoxyelephantopin (DET) isolated from Elephantopus scaber in LPS-induced neuroinflammatory rat model.

MATERIALS AND METHODS

In this study, DET (0.625. 1.25 and 2.5 mg/kg, i.p.) was administered in rats for 21 days and those animals were challenged with single injection of LPS (250 μg/kg, i.p.) for 7 days. Cognitive and behavioral assessment was carried out for 7 days followed by molecular assessment on brain hippocampus. Statistical significance was analyzed with one-way analysis of variance followed by Dunnett's test to compare the treatment groups with the control group.

KEY FINDINGS

DET ameliorated LPS-induced neuroinflammation by suppressing major pro-inflammatory mediators such as iNOS and COX-2. Furthermore, DET enhanced the anti-inflammatory cytokines and concomitantly suppressed the pro-inflammatory cytokines and chemokine production. DET treatment also reversed LPS-induced behavioral and memory deficits and attenuated LPS-induced elevation of the expression of AD markers. DET improved synaptic-functionality via enhancing the activity of pre- and post-synaptic markers, like PSD-95 and SYP. DET also prevented LPS-induced apoptotic neurodegeneration via inhibition of PARP-1, caspase-3 and cleaved caspase-3.

SIGNIFICANCE

Overall, our studies suggest DET can prevent neuroinflammation-associated memory impairment and neurodegeneration and it could be developed as a therapeutic agent for the treatment of neuroinflammation-mediated and neurodegenerative disorders, such as AD.

Molecular identification of Trichodina compacta Van As and Basson, 1989 (Ciliophora: Peritrichia) from cultured Oreochromis niloticus in Egypt and its impact on immune responses and tissue pathology

Trichodinids are peritrichous ciliated protozoa that affect both wild and cultured fishes. Several Trichodina species have low host specificity and are morphologically distinct, facilitating their identification based primarily on the presence of adhesive discs and the number of attached denticles. A trichodinid species named Trichodina compacta was first reported by Van As and Basson (1989) (Protozoa: Ciliophora: Peritrichia). However, in trichodinid infestations, morphological characteristics are insufficient for identifying the infesting species. Therefore, molecular and phylogenetic analyses are considered to be promising and useful tools for identifying the infesting species. This study aimed to achieve the molecular identification of a trichodinid infestation in Nile tilapia and to construct the phylogenetic relationships between the identified species and other peritrichous parasites. Moreover, we also aimed to study the pathological and immunological impacts of trichodinids on fry tissue to improve our understanding of the immune responses of teleost fish to trichodinae parasitic infestations and develop a better control method. Here, we used molecular techniques to identify the isolated trichodina species as T. compacta and demonstrated that Trichodina infestation in Nile tilapia is associated with remarkable immunogenic and inflammatory responses (increased il-1β expression and decreased il-8 and tgf-β expression). These findings improve our understanding of the responses of teleost fish to trichodinid parasite infestation and will be helpful for the development of novel control strategies that reverse the inflammatory and immunogenic alterations that occur in infested fish.

Methadone against cancer: Lost in translation

Recently, the opioid analgesic d,l-methadone has gained much attention as a potential antineoplastic compound, considerably triggered through lay press and media. In consequence, physicians and pharmacists are currently confronted with numerous patients willing to use d,l-methadone against their malignancies. Well-performed in vitro and in vivo models have in fact shown pro-apoptotic effects of d,l-methadone or other opioids, but also proliferation-stimulating properties. Moreover, the mechanisms of proposed opioid-stimulated apoptosis are incompletely described or contradicting. Finally, the receptors mostly responsible for induction of apoptosis by d,l-methadone remain unclear as contributions of both µ-opioid receptors, Fas cell death receptors, toll-like receptors, N-Methyl-d-aspartate receptors and opioid growth factor receptors were suggested. Such ambiguity prevents rational application of d,l-methadone or patient stratification to enhance beneficial antineoplastic effects. From a clinical point of view, d,l-methadone and other opioids might in fact prolong survival, but such effects likely originate from their analgesic and neuro-psychotropic properties and, thus, improvements of quality of life. Crucial obstacles to the administration of d,l-methadone are incomplete knowledge about its systemic disposition, highly variable pharmacokinetics, profound drug-drug- or drug-disease interaction and QT-prolongation potential. This article summarizes and rates the pharmacological basis of d,l-methadone as an antineoplastic agent and puts its administration in clinical oncology into perspective. Despite enthralling experimental findings about d,l-methadone-mediated apoptosis in cancerous cells or tissues, clinicians should realize the current lack of evidence for the use of d,l-methadone as an antineoplastic agent. Its administration against cancer pain is, however, tenable, albeit restricted to certain clinical situations.

High Mobility Group Box 1 Influences HSV1716 Spread and Acts as an Adjuvant to Chemotherapy

High Mobility Group Box 1 (HMGB1) is a multifunctional protein that plays various roles in the processes of inflammation, cancer, and other diseases. Many reports document abundant HMGB1 release following infection with oncolytic viruses (OVs). Further, other groups including previous reports from our laboratory highlight the synergistic effects of OVs with chemotherapy drugs. Here, we show that virus-free supernatants have varying cytotoxic potential, and HMGB1 is actively secreted by two established fibroblast cell lines (NIH 3T3 and 3T6-Swiss albino) following HSV1716 infection in vitro. Further, pharmacologic inhibition or genetic knock-down of HMGB1 reveals a role for HMGB1 in viral restriction, the ability to modulate bystander cell proliferation, and drug sensitivity in 3T6 cells. These data further support the multifactorial role of HMGB1, and suggest it could be a target for modulating the efficacy of oncolytic virus therapies alone or in combination with other frontline cancer treatments.