Comparative Transcriptome Analysis Reveals the Molecular Immunopathogenesis of Chinese Soft-Shelled Turtle (Trionyx sinensis) Infected with Aeromonas hydrophila

Although hemorrhagic sepsis caused by Aeromonas hydrophila infection is the dominant disease in the aquaculture of Chinese soft-shelled turtle, information on its molecular pathology is seriously limited. In this study, ninety turtles intraperitoneally injected with A. hydrophila exhibited two different phenotypes based on the pathological symptoms, referred to as active and inactive turtles. Comparative transcriptomes of liver and spleen from these two groups at 6, 24, and 72 hours post-injection (hpi) were further analyzed. The results showed that cytokine–cytokine receptor interaction, PRRs mediated signaling pathway, apoptosis, and phagocytosis enriched in active and inactive turtles were significantly different. Pro-inflammatory cytokines, the TLR signaling pathway, NLR signaling pathway, and RLR signaling pathway mediating cytokine expression, and apoptosis-related genes, were significantly up-regulated in inactive turtles at the early stage (6 hpi). The significant up-regulation of phagocytosis-related genes occurred at 24 hpi in inactive turtles and relatively lagged behind those in active turtles. The anti-inflammatory cytokine, IL10, was significantly up-regulated during the tested periods (6, 24, and 72 hpi) in active turtles. These findings offer valuable information for the understanding of molecular immunopathogenesis after A. hydrophila infection, and facilitate further investigations on strategies against hemorrhagic sepsis in Chinese soft-shelled turtle T. sinensis.

Polysaccharide from Patinopecten yessoensis Skirt Boosts Immune Response via Modulation of Gut Microbiota and Short-Chain Fatty Acids Metabolism in Mice

Polysaccharide from marine shellfish has various bioactivities. In this study, the effects of polysaccharide from Patinopecten yessoensis skirt (PS) on boosting immune response in mice were evaluated, and the potential mechanisms were explored. The results showed that PS administration effectively increased the serum IgG and IgM levels, implying that PS had immune response-boosting properties. Moreover, PS administration could modulate the composition of the gut microbiota, and significantly improve short-chain fatty acids (SCFAs) metabolism, especially butyrate metabolism. Of note, the expression of the Tlr2, Tlr7, MyD88, Tnfa, and Il1b genes in toll-like receptor (TLR) signaling pathway was significantly increased. In summary, PS could boost immune response by modulating the gut microbiota and SCFAs metabolism correlating with the activation of the TLR signaling pathway. Therefore, PS can be developed as a special ingredient for functional product.

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.

A20 Inhibits LPS-Induced Inflammation by Regulating TRAF6 Polyubiquitination in Rainbow Trout

The ubiquitin-editing enzyme A20 is known to inhibit the NF-κB transcription factor in the Toll-like receptor (TLR) pathways, thereby negatively regulating inflammation. However, its role in the TLR signaling pathway in fish is still largely unknown. Here, we identified a gene encoding A20 (OmA20) in rainbow trout, Oncorhynchus mykiss, and investigated its role in TLR response regulation. The deduced amino acid sequence of OmA20 contained a conserved N-terminal ovarian tumor (OTU) domain and seven C-terminal zinc-finger (ZnF) domains. Lipopolysaccharide (LPS) stimulation increased OmA20 expression in RTH-149 cells. In LPS-stimulated RTH-149 cells, gain- and loss-of-function experiments revealed that OmA20 inhibited MAPK and NF-κB activation, as well as the expression of pro-inflammatory cytokines. OmA20 interacted with TRAF6, a key molecule involved in the activation of TLR-mediated NF-κB signaling pathways. LPS treatment increased the K63-linked polyubiquitination of TRAF6 in RTH-149 cells, which was suppressed when OmA20 was forced expression. Furthermore, mutations in the OTU domain significantly decreased deubiquitination of the K63-linked ubiquitin chain on TRAF6, indicating that deubiquitinase activity is dependent on the OTU domain. These findings suggest that OmA20, like those of mammals, reduces LPS-induced inflammation in rainbow trout, most likely by regulating K63-linked ubiquitination of TRAF6.

Gene Profiling of Toll-like Receptor Signaling Pathways in Neutrophils of Patients With Acute-on-chronic Liver Failure

Objectives: Toll-like receptors (TLRs) of neutrophils play a crucial role in detecting pathogens and organ/tissue injury in acute-on-chronic liver failure (ACLF). However, little is known about the exact mechanisms and the potential signaling pathways. The aim of this study was to investigate alterations of TLR signaling pathways in neutrophils of ACLF patients.Methods: Twenty-seven patients with compensated cirrhosis (n=9), de-compensated cirrhosis (n=9) and ACLF (n=9) were enrolled in the study. Neutrophils were isolated, and alterations in TLR signaling pathways were evaluated using an RT² Profiler™ PCR Array. The fold change for each gene (2(-∆∆CT)) was compared among the groups. Genes with a fold change ratio of ≥2 or ≤0.5 along with a p value of < 0.05 were considered to be differentially expressed.Results: A total of 17 genes were up-regulated in neutrophils from patients with compensated cirrhosis, which were mainly distributed in adaptors, TLR-interacting proteins and downstream pathways. Six genes were detected in patients with de-compensated cirrhosis. A trend of down-regulation of genes in the TLR signaling pathway was observed in neutrophils of patients with cirrhosis and ACLF. TLR3, IFNG, IL1B, TBK1, CCL2 and LTA were downregulated in neutrophils. Moreover, CD14 and IL10 were up regulated in neutrophils of ACLF patients.Conclusions: TLR signaling pathway genes were differentially regulated in neutrophils between cirrhosis and ACLF. In ACLF patients, there was defective expression of TLR3 and IFN, along with enhanced CD14 and IL10 expression, characterized by transcriptional alterations of neutrophils.

Toll-Like Receptor Signaling Pathways: Novel Therapeutic Targets for Cerebrovascular Disorders

Toll-like receptors (TLRs), a class of pattern recognition proteins, play an integral role in the modulation of systemic inflammatory responses. Cerebrovascular diseases (CVDs) are a group of pathological conditions that temporarily or permanently affect the brain tissue mostly via the decrease of oxygen and glucose supply. TLRs have a critical role in the activation of inflammatory cascades following hypoxic-ischemic events and subsequently contribute to neuroprotective or detrimental effects of CVD-induced neuroinflammation. The TLR signaling pathway and downstream cascades trigger immune responses via the production and release of various inflammatory mediators. The present review describes the modulatory role of the TLR signaling pathway in the inflammatory responses developed following various CVDs and discusses the potential benefits of the modulation of different TLRs in the improvement of functional outcomes after brain ischemia.

Evaluation of E. coli Nissle1917 derived metabolites in modulating key mediator genes of the TLR signaling pathway

Objective Gut-microbiota plays key roles in many aspects like the health and illness of humans. It's well proved that modification of gut microbiota by probiotics is useful for improving inflammatory bowel disease (IBD) conditions. According to recent studies, different types of bacterial metabolites can affect immune cells and inflammation conditions. The present study aimed to evaluate the anti-inflammatory effects of metabolites of E. coli Nissle1917. Results The cell-free supernatant could modulate TNF-α production and affected many crucial mediators in the Toll-like receptor (TLR) signaling pathway. Also, supernatant showed significant dose-dependent properties in this regard. In this study, the TLR signaling pathway was found among probable mechanisms by which probiotics can affect inflammatory situations. These findings provide additional evidence on the use of probiotic metabolites for inhibiting and down-regulating numerous key mediator factors in the TLR signaling pathway. Aberrant or dysfunctional TLR signaling contributes to the development of acute and chronic intestinal inflammatory pathways in IBD. Therefore, finding a component that can affect this process might be considered for therapeutic targets in IBD patients.

A LRRK2 GTP Binding Inhibitor, 68, Reduces LPS-Induced Signaling Events and TNF-α Release in Human Lymphoblasts

Mutations in the leucine-rich repeat kinase-2 (LRRK2) gene cause autosomal-dominant Parkinson’s disease (PD) and contribute to sporadic PD. Common genetic variation in LRRK2 modifies susceptibility to immunological disorders including Crohn’s disease and leprosy. Previous studies have reported that LRRK2 is expressed in B lymphocytes and macrophages, suggesting a role for LRRK2 in immunological functions. In this study, we characterized the LRRK2 protein expression and phosphorylation using human lymphoblasts. Lipopolysaccharide (LPS), a proinflammatory agent, induced the increase of LRRK2 expression and kinase activities in human lymphoblasts in a time-dependent manner. Moreover, LPS activated the Toll-like receptor (TLR) signaling pathway, increased TRAF6/LRRK2 interaction, and elevated the phosphorylation levels of MAPK (JNK1/2, p38, and ERK1/2) and IkBα. Treatment with LRRK2 inhibitor 68 reduced LPS-induced TRAF6/LRRK2 interaction and MAPK and IkBα phosphorylation, thereby reducing TNF-α secretion. These results indicate that LRRK2 is actively involved in proinflammatory responses in human lymphoblasts, and inhibition of GTP binding by 68 results in an anti-inflammation effect against proinflammatory stimuli. These findings not only provide novel insights into the mechanisms of LRRK2-linked immune and inflammatory responses in B-cell-like lymphoblasts, but also suggest that 68 may also have potential therapeutic value for LRRK2-linked immunological disorders.

Buffalo Gut Microbes May Affect the Host Th2 Responses During Fasciola Gigantica Infection via SCFAs Metabolism and TLR Signaling Pathway

Background: Helminth-induced Th2 responses are essential to modify the structure and diversity of gut microbes. However, observations have come mainly from studies of helminth-infected humans or rodent models. Very little research has been conducted in veterinary animals. Methods: In this study, we searched for links between microbiota and Th2-biased responses during the time course of Fasciala gigantica infection in buffaloes.16S rRNA gene amplicon and metagenome sequencing were applied to analyze the structure and function of the gut microbiota. Results: Both alpha and beta diversities decreased during infection, and gut microbes differed considerably across different sections of the gut at different stages. Immune responses changed when the microbiota traverses the gut wall into the peritoneal cavity, in line with the changes in Th2 response induced by F. gigantica infection. We found that the order Coriobacteriales was greatly decreased at the early stages in which the Peptostreptococcaceae and Family_XIII families are closely linked to the upregulation of IgG1 and IL4, respectively. The F. gigantica infection significantly reduced short-chain fatty acid (SCFAs)-producing microbes, reduced the concentrations of gut SCFAs and downregulated the SCFAs-producing metabolic pathways. In addition, The microbes associated with TLR2 increased and showed similar trend to the TLR2 and Th2 cytokine production during infection, suggesting that bacteria ligands might recognize TLR2 and subsequently induce a Th2-biased response. Conclusions: Our data show that buffalo gut microbes may affect the host Th2 response during F. gigantica infection via the SCFAs metabolism and TLR signaling pathway. These findings provide new insights into the relationship between F. gigantica–microbiota-host, which may provide new potential therapeutic targets for prevention and control Fasciolosis.

miR-26a-5p mediates TLR signaling pathway by targeting CTGF in LPS-induced alveolar macrophage

To explore the regulation mechanism of miR-26a-5p and connective tissue growth factor (CTGF) in lipopolysaccharide (LPS)-induced alveolar macrophages, which is a severe pneumonia cell model. MH-S cells were grouped into Normal group, Model group, negative control (NC) group, miR-26a-5p mimic group, oe-CTGF group, miR-26a-5p mimic + oe-CTGF group. The expression level of miR-26a-5p, CTGF and Toll-like receptor (TLR) signaling related molecules (TLR2, TLR4 and nuclear factor-κB p65) were detected by qRT-PCR and WB, respectively. The cell viability and apoptosis rate were detected by methyl thiazolyl tetrazolium (MTT) and flow cytometry, respectively. Compared with the Normal group, the expression level of miR-26a-5p was significantly decreased, while CTGF protein level was significantly increased in the Model group. Compared with the Model group, MH-S cells with miR-26a-5p overexpression showed enhanced cell viability, decreased apoptosis rate, declined expression level of TLR signaling related molecules and reduced level of tumor necrosis factor-α (TNF-α), interleukin (IL) 6 (IL-6) and IL-1β, while those with CTGF overexpression had an opposite phenotype. In conclusion, miR-26a-5p can inhibit the expression of CTGF and mediate TLR signaling pathway to inhibit the cell apoptosis and reduce the expression of proinflammatory cytokines in alveolar macrophages which is a cell model of severe pneumonia.