TLR Signaling in Brain Immunity.

Toll-like receptors (TLRs) comprise a group of transmembrane proteins with crucial roles in pathogen recognition, immune responses, and signal transduction. This family represented the first line of immune homeostasis in an evolutionarily conserved manner. Extensive researches in the past two decades had emphasized their structural and functional characteristics under both healthy and pathological conditions. In this review, we summarized the current understanding of TLR signaling in the central nervous system (CNS), which had been viewed as a previously "immune-privileged" but now "immune-specialized" area, with major implications for further investigation of pathological nature as well as potential therapeutic manipulation of TLR signaling in various neurological disorders.

First Discovery of Beta-Sitosterol as a Novel Antiviral Agent against White Spot Syndrome Virus.

The outbreak of white spot syndrome (WSS) is a looming challenge, due to dramatic losses to the crustacean aquaculture industry. However, at present, there are no prophylactic or therapeutic means to control this infectious viral disease. Here, we screened fifteen medicinal plants for their inhibitory activity on the white spot syndrome virus (WSSV), using red swamp crayfish (Procambarus clarkii) as a model species. The results showed that the crude extracts of Pinellia ternata (Thunb.) Breit. had the highest inhibitory effect (91.59%, 100 mg/kg) on WSSV proliferation, and its main component, beta-sitosterol, showed a much higher activity (95.79%, 50 mg/kg). Further, beta-sitosterol potently reduced (p < 0.01) viral loads and viral gene transcription levels in a concentration-dependent fashion, and significantly promoted the survival rate of WSSV-challenged crayfish (57.14%, 50 mg/kg). The co-incubation assay indicated that beta-sitosterol did not influence the infectivity of WSSV particles. Both pre- and post-treatment of beta-sitosterol exerted a significant inhibitory effect (p < 0.01) on the viral load in vivo. Mechanistically, beta-sitosterol not only interfered with the expression of viral genes (immediate early gene 1, ie1; DNA polymerase, DNApol) that are important in initiating WSSV transcription, but it also attenuated the hijacking of innate immune signaling pathways (Toll, IMD, and JAK/STAT pathways) by viral genes to block WSSV replication. Moreover, the expression of several antiviral immune, antioxidant, pro-inflammatory, and apoptosis-related genes changed significantly in beta-sitosterol-treated crayfish. Beta-sitosterol is a potent WSSV inhibitor and has the potential to be developed as an effective anti-WSSV agent against a WSS outbreak in crustacean aquaculture.

Yarrowia lipolytica N6-glucan protects goat leukocytes against Escherichia coli by enhancing phagocytosis and immune signaling pathway genes.

Immunostimulant and protective effects of Yarrowia lipolytica glucans against important pathogens, such as Escherichia coli, have not been investigated in goats and other ruminants. This study aimed to characterize Y. lipolytica N6-glucan (Yl-glucan) and its possible role in immunological signaling pathway activation and immunoprotection against E. coli in goat leukocytes. Characterization analyses showed that Y. lipolytica content had a mix of ß and α-D-glucans, molecular weight of 3301.53 kDa and low solubility after the heat treatment. The stimulation of goat leukocytes with Yl-glucan induced protection against E. coli challenge. Remarkably, Yl-glucan and E. coli interaction increased gene expression of dectin-1 and TLR-2 receptors, signaling pathway Syk/NFκB, and cytokines, such as TNF-α and IL-10. As a consequence of signaling activation, phagocytosis, and nitric oxide production enhanced killing of pathogens. Altogether, Y. lipolytica-glucan demonstrated to possess an immunoprotective potential against E. coli through innate immune response modulation in goat leukocytes.

Identification and functional characterization of three TLR signaling pathway genes in Cyclina sinensis.

Toll-like receptors (TLRs) are an ancient family of pattern recognition receptors that play a critical role in initiating and activating the innate immune system. In this study, we identified two TLR genes (CsTLR4 and CsTLR13) and the MyD88 (CsMyD88) gene using a transcriptome library from Cyclina sinensis. The sequence features and mRNA expression profiles of the genes were characterized, and their functions in the immune response were investigated to validate the TLR signaling pathway and its potential role in immune defense. The expression patterns of CsTLR4, CsTLR13 and CsMyD88 were detected in all the tissues examined from healthy clams and were primarily expressed in the hemocytes (P < 0.05), as shown by real-time PCR. Upon challenge with Vibrio anguillarum and Micrococcus luteus, they were significantly increased in hemocytes (P < 0.01), whereas only CsTLR13 and CsMyD88 were up-regulated (P < 0.01) by poly (I:C) challenge. In addition, the mRNA expression level of CsC-LYZ and CsAMP was down-regulated at 72 h (P < 0.01) after injection with CsMyD88 RNAi. These findings might be valuable for understanding the innate immune signaling pathways of C. sinensis and enabling future studies on host-pathogen interactions.

Recent trends in insect gut immunity.

The gut is a crucial organ in insect defense against various pathogens and harmful substances in their environment and diet. Distinct insect gut compartments possess unique functionalities contributing to their physiological processes, including immunity. The insect gut's cellular composition is vital for cellular and humoral immunity. The peritrophic membrane, mucus layer, lumen, microvilli, and various gut cells provide essential support for activating and regulating immune defense mechanisms. These components also secrete molecules and enzymes that are imperative in physiological activities. Additionally, the gut microbiota initiates various signaling pathways and produces vitamins and minerals that help maintain gut homeostasis. Distinct immune signaling pathways are activated within the gut when insects ingest pathogens or hazardous materials. The pathway induced depends on the infection or pathogen type; include immune deficiency (imd), Toll, JAK/STAT, Duox-ROS, and JNK/FOXO regulatory pathways. These pathways produce different antimicrobial peptides (AMPs) and maintain gut homeostasis. Furthermore, various signaling mechanisms within gut cells regulate insect gut recovery following infection. Although some questions regarding insect gut immunity in different species require additional study, this review provides insights into the insect gut's structure and composition, commensal microorganism roles in Drosophila melanogaster and Tenebrio molitor life cycles, different signaling pathways involved in gut immune systems, and the insect gut post-infection recovery through various signaling mechanisms.

Azadirachtin interferes with basal immunity and microbial homeostasis in the Rhodnius prolixus midgut.

Rhodnius prolixus is an insect vector of two flagellate parasites, Trypanosoma rangeli and Trypanosoma cruzi, the latter being the causative agent of Chagas disease in Latin America. The R. prolixus neuroendocrine system regulates the synthesis of the steroid hormone ecdysone, which is essential for not only development and molting but also insect immunity. Knowledge for how this modulates R. prolixus midgut immune responses is essential for understanding interactions between the vector, its parasites and symbiotic microbes. In the present work, we evaluated the effects of ecdysone inhibition on R. prolixus humoral immunity and homeostasis with its microbiota, using the triterpenoid natural product, azadirachtin. Our results demonstrated that azadirachtin promoted a fast and lasting inhibitory effect on expression of both RpRelish, a nuclear factor kappa B transcription factor (NF-kB) component of the IMD pathway, and several antimicrobial peptide (AMP) genes. On the other hand, RpDorsal, encoding the equivalent NF-kB transcription factor in the Toll pathway, and the defC AMP gene were upregulated later in azadirachtin treated insects. The treatment also impacted on proliferation of Serratia marcescens, an abundant commensal bacterium. The simultaneous administration of ecdysone and azadirachtin in R. prolixus blood meals counteracted the azadirachtin effects on insect molting and also on expression of RpRelish and AMPs genes. These results support the direct involvement of ecdysone in regulation of the IMD pathway in the Rhodnius prolixus gut.

Dietary Chito-oligosaccharides Improve Intestinal Immunity via Regulating Microbiota and Th17/Treg Balance-Related Immune Signaling in Piglets Challenged by Enterotoxigenic E. coli.

This study was conducted to investigate how chito-oligosaccharides (COSs) affect the growth performance and immune stress response and to further explain their mechanisms. A total of 32 boars that were 28 days old and three-way weaned were randomly allotted to four equal groups [CON (basal diet) group, enterotoxigenic Escherichia coli (ETEC) group, COS group, and COS*ETEC group]. The results showed that COS partially reversed the negative changes in the average daily gain and average daily feed intake caused by the ETEC challenge and thereby alleviated the increase in the feed conversion ratio. Dietary COS increased the villus length as compared with the CON group and improved the ileal morphological structure. Additionally, it increased the bacterial diversity and Bacteroidetes abundance and lowered the Firmicutes abundance and Firmicutes-to-Bacteroidetes ratio at the phylum level. COS treatment lowered the abundance of Lactobacillus, Streptococcus, and Anarovovrio in the intestines of piglets, while it increased Muribaculaceae_unclassified and Prevotella at the genus level. COS had a significant inhibitory effect on the increase in the relative expression abundance of STAT3 mRNA caused by ETEC. The IL-10 and FOXP3 mRNAs were found to be significantly lower in the COS, ETEC, and COS*ETEC groups as compared to the CON group. These results demonstrate that COS could be beneficial for improving the growth performance and attenuating ETEC-challenged intestinal inflammation via regulating microbiota and Th17/Treg balance-related immune signaling pathways.

Effect of Application of Probiotic Pollen Suspension on Immune Response and Gut Microbiota of Honey Bees (Apis mellifera).

Although the use of probiotic bacteria in invertebrates is still rare, scientists have begun to look into their usage in honey bees. The probiotic preparation, based on the autochthonous strain Lactobacillus brevis B50 Biocenol™ (CCM 8618), which was isolated from the digestive tracts of healthy bees, was applied to the bee colonies in the form of a pollen suspension. Its influence on the immune response was determined by monitoring the expression of genes encoding immunologically important molecules in the honey bee intestines. Changes in the intestinal microbiota composition were also studied. The results showed that the probiotic Lact. brevis B50, on a pollen carrier, significantly increased the expression of genes encoding antimicrobial peptides (abaecin, defensin-1) as well as pattern recognition receptors (toll-like receptor, peptidoglycan recognition proteins). Gene expression for the other tested molecules included in Toll and Imd signaling pathways (dorsal, cactus, kenny, relish) significantly changed during the experiment. The positive effect on intestinal microbiota was manifested mainly by a significant increase in the ratio of lactic acid bacteria to enterobacteria. These findings confirm the potential of the tested probiotic preparation to enhance immunity in bee colonies and thus increase their resistance to infectious diseases and stress conditions.

Targeting Immune Signaling Pathways in Clonal Hematopoiesis.

BACKGROUND: Myeloid neoplasms are a diverse group of malignant diseases with different entities and numerous patho-clinical features. They arise from mutated clones of hematopoietic stem- and progenitor cells which expand by outperforming their normal counterparts. The intracellular signaling profile of cancer cells is the sum of genetic, epigenetic and microenvironmental influences, and the multiple interconnections between different signaling pathways make pharmacological targeting complicated. OBJECTIVE: To present an overview of known somatic mutations in myeloproliferative neoplasms (MPN), myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) and the inflammatory signaling pathways affected by them, as well as current efforts to therapeutically modulate this aberrant inflammatory signaling. METHODS: In this review, we extensively reviewed and compiled salient information with ClinicalTrials.gov as our source on ongoing studies, and PubMed as our authentic bibliographic source, using a focused review question. RESULTS: Mutations affecting immune signal transduction are present to varying extents in clonal myeloid diseases. While MPN are dominated by a few common mutations, a multitude of different genes can be mutated in MDS and AML. Mutations can also occur in asymptomatic persons, a finding called clonal hematopoiesis of indeterminate potential (CHIP). Mutations in FLT3, JAK, STAT, CBL and RAS can lead to aberrant immune signaling. Protein kinase inhibitors are entering the clinic and are extensively investigated in clinical trials in MPN, MDS and AML. CONCLUSION: In summary, this article summarizes recent research on aberrant inflammatory signaling in clonal myeloid diseases and the clinical therapeutic potential of modulation of signal transduction and effector proteins in the affected pathways.

MicroRNA mediated network motifs in autoimmune diseases and its crosstalk between genes, functions and pathways.

Autoimmune diseases (AIDs) are incurable but suppressible diseases whose molecular mechanisms are yet to be elucidated. In this work, we selected five systemic autoimmune diseases such as Rheumatoid Arthritis (RA), Type 1 Diabetes (T1D), Inflammatory Bowel Disease (IBD), Autoimmune Thyroid Disease (ATD) and Systemic Lupus Erythematosus (SLE). Heterogeneous data such as miRNA, transcription factor (TF), target genes and protein-protein interactions involved in these AIDs were integrated to understand their roles at different functional levels of miRNA such as transcription initiation, gene regulatory network formation and post transcriptional regulation. To understand the functional characteristics of these complex biological networks, they can be simplified as network motifs (sub networks) and motif-motif interacting pairs (MMIs). The network motif patterns and motif-motif interacting pairs that occur for the selected five diseases were identified. To further understand the functional association between AIDs, functions and pathways were determined using gene set enrichment analysis and five selected immune signaling pathways (ISPs). The crosstalk within AIDs and between the immune signaling pathways (ISPs) could provide novel insights in deciphering disease mechanisms. This study represents the first investigation of miRNA-TF regulatory network for AIDs and its association with ISPs using sub-network motifs.