TRIF-dependent TLR signaling, its functions in host defense and inflammation, and its potential as a therapeutic target

Screening optimal DC-targeting peptide to enhance the immune efficacy of recombinant Lactobacillus expressing RHDV VP60

Dendritic cells (DCs) present an ideal target for delivering immunogenic cargo due to their potent antigen-presenting capabilities. This targeting approach holds promise in vaccine development by enhancing the efficiency of antigen recognition and capture by DCs. To identify a high-affinity targeting peptide binding to rabbit DCs, rabbit monocyte-derived DCs (raMoDCs) were isolated and cultured, and a novel peptide, HS (HSLRHDYGYPGH), was identified using a phage-displayed peptide library. Alongside HS, two other DC-targeting peptides, KC1 and MY, previously validated in our laboratory, were employed to construct recombinant Lactgobacillus reuteri fusion-expressed rabbit hemorrhagic disease virus (RHDV) capsid protein VP60. These recombinant Lactobacillus strains were named HS-VP60/L. reuteri, KC1-VP60/L. reuteri, and MY-VP60/L. reuteri. The ability of these recombinant Lactobacillus to bind rabbit DCs was evaluated both in vivo and in vitro. Results demonstrated that the DC-targeting peptide KC1 significantly enhanced the capture efficiency of recombinant Lactobacillus by raMoDCs, promoted DC maturation, and increased cytokine secretion. Furthermore, oral administration of KC1-VP60/L. reuteri effectively induced SIgA and IgG production in rabbits, prolonged rabbit survival post-challenge, and reduced RHDV copies in organs. In summary, the DC-targeting peptide KC1 exhibited robust binding to raMoDCs, and recombinant Lactobacillus expressing KC1-VP60 protein antigens efficiently induced systemic and mucosal immune responses in rabbits, conferring protective efficacy against RHDV. This study offers valuable insights for the development of novel RHDV vaccines.

Hypoxia-inducible factor-driven glycolytic adaptations in host-microbe interactions

Mammalian cells utilize glucose as a primary carbon source to produce energy for most cellular functions. However, the bioenergetic homeostasis of cells can be perturbed by environmental alterations, such as changes in oxygen levels which can be associated with bacterial infection. Reduction in oxygen availability leads to a state of hypoxia, inducing numerous cellular responses that aim to combat this stress. Importantly, hypoxia strongly augments cellular glycolysis in most cell types to compensate for the loss of aerobic respiration. Understanding how this host cell metabolic adaptation to hypoxia impacts the course of bacterial infection will identify new anti-microbial targets. This review will highlight developments in our understanding of glycolytic substrate channeling and spatiotemporal enzymatic organization in response to hypoxia, shedding light on the integral role of the hypoxia-inducible factor (HIF) during host-pathogen interactions. Furthermore, the ability of intracellular and extracellular bacteria (pathogens and commensals alike) to modulate host cellular glucose metabolism will be discussed.

Xiaowugui decoction alleviates experimental rheumatoid arthritis by suppressing Rab5a-mediated TLR4 internalization in macrophages

BACKGROUND

Rheumatoid arthritis (RA) is a chronic autoimmune disorder characterized by exacerbated synovial inflammation and joint destruction. Recent studies suggest toll-like receptor 4 (TLR4) internalization facilitate inflammatory response of macrophage. The role of TLR4 internalization in the pathogenesis of RA is unknown.

PURPOSE

To investigate the role and mechanism of TLR4 internalization in macrophage inflammatory response of RA and explore whether TLR4 internalization mediates the anti-arthritic effect of Xiaowugui (XWG) decoction, a patented herbal formula used in China.

METHODS

The co-expression of TLR4 and the internalization marker, early endosome antigen 1 (EEA1), in the synovial samples of RA patients and joint tissue of collagen-induced arthritis (CIA) mice, were evaluated using immunofluorescence. The effect of Rab5a-mediated early internalization of TLR4 on the activation induced by lipopolysaccharide (LPS) in RAW264.7 cells was investigated using small interfering RNAs that act against Rab5a. CIA was induced in Rab5a-/- mice to evaluate the role of Rab5a in vivo. The disease progression and expression of Rab5a and TLR4 in the joint tissue were evaluated in CIA mice treated with XWG. Inflammatory factors production, TLR4 internalization, and activation of downstream signaling pathways were examined in RAW264.7 cells treated with XWG in vitro.

RESULTS

The co-expression and co-localization of TLR4 and EEA1 were elevated in the synovial samples of RA patients and joint tissue of CIA mice. Pharmaceutical inhibition of TLR4 internalization reduced macrophages inflammatory responses induced by LPS. The co-expression and co-localization of Rab5a and TLR4 were significantly increased in macrophages treated with LPS. Silencing Rab5a reduced LPS-induced TLR4 internalization, inflammatory factors production, and phosphorylation of Jun N-terminal kinases (JNK) and p65. Genetic deletion of Rab5a inhibited TLR4 internalization and the development of arthritis in vivo. The co-expression of TLR4 and Rab5a was also elevated in the synovial samples of RA patients. XWG treatment of mice with CIA alleviated arthritis and reduced the co-expression of Rab5a and TLR4 in the joint tissue. XWG treatment of macrophage inhibited LPS-induced IL-6 and TNF-α production, co-expression of Rab5a and TLR4, and phosphorylation of JNK and p65.

CONCLUSIONS

Our findings highlight the pathogenic role of TLR4 internalization in patients with RA and identify a novel Rab5a-dependent internalization pathway that promotes macrophage inflammatory response. XWG treatment demonstrated outstanding therapeutic effects in experimental arthritis, and targeting the Rab5a-mediated internalization of TLR4 may be the main underlying mechanism.

Lipid Nanoparticles Elicit Reactogenicity and Sickness Behavior in Mice Via Toll-Like Receptor 4 and Myeloid Differentiation Protein 88 Axis

mRNA therapeutics encapsulated in lipid nanoparticles (LNPs) offer promising avenues for treating various diseases. While mRNA vaccines anticipate immunogenicity, the associated reactogenicity of mRNA-loaded LNPs poses significant challenges, especially in protein replacement therapies requiring multiple administrations, leading to adverse effects and suboptimal therapeutic outcomes. Historically, research has primarily focused on the reactogenicity of mRNA cargo, leaving the role of LNPs understudied in this context. Adjuvanticity and pro-inflammatory characteristics of LNPs, originating at least in part from ionizable lipids, may induce inflammation, activate toll-like receptors (TLRs), and impact mRNA translation. Knowledge gaps remain in understanding LNP-induced TLR activation and its impact on induction of animal sickness behavior. We hypothesized that ionizable lipids in LNPs, structurally resembling lipid A from lipopolysaccharide, could activate TLR4 signaling via MyD88 and TRIF adaptors, thereby propagating LNP-associated reactogenicity. Our comprehensive investigation utilizing gene ablation studies and pharmacological receptor manipulation proves that TLR4 activation by LNPs triggers distinct physiologically meaningful responses in mice. We show that TLR4 and MyD88 are essential for reactogenic signal initiation, pro-inflammatory gene expression, and physiological outcomes like food intake and body weight─robust metrics of sickness behavior in mice. The application of the TLR4 inhibitor TAK-242 effectively reduces the reactogenicity associated with LNPs by mitigating TLR4-driven inflammatory responses. Our findings elucidate the critical role of the TLR4-MyD88 axis in LNP-induced reactogenicity, providing a mechanistic framework for developing safer mRNA therapeutics and offering a strategy to mitigate adverse effects through targeted inhibition of this pathway.

Resolution of chronic inflammation and cancer

Chronic inflammation poses challenges to effective cancer treatment. Although anti-inflammatory therapies have shown short-term benefits, their long-term implications may be unfavorable because they fail to initiate the necessary inflammatory responses. Recent research underscores the promise of specialized pro-resolving mediators, which play a role in modulating the cancer microenvironment by promoting the resolution of initiated inflammatory processes and restoring tissue hemostasis. This review addresses current insights into how inflammation contributes to cancer pathogenesis and explores recent strategies to resolve inflammation associated with cancer.

Molecular mechanisms underlying cyclophosphamide-induced cognitive impairment and strategies for neuroprotection in preclinical models

Cyclophosphamide has drastically enhanced the expectancy and quality of life of cancer patients. However, it is accompanied by diverse neurological complications which are considered a dose-limiting adverse effect. Neurotoxicity caused by cyclophosphamide can manifest in numerous manners including anxiety, depression, motor dysfunction and cognitive deficits. This review article offers an overview on cyclophosphamide-induced neurotoxicity, providing a unified point of view on the possible underlying molecular mechanisms including oxidative brain damage, neuroinflammation, apoptotic neuronal cell death as well as disruption of the balance of brain neurotransmitters and neurotrophic factors. Besides, this review sheds light on the promising protective agents that have been investigated using preclinical animal models as well as their biological targets and protection mechanisms. Despite promising results in experimental models, none of these agents has been studied in clinical trials. Thus, there is lack of evidence to advocate the use of any neuroprotective agent in the clinical setting. Furthermore, none of the protective agents has been evaluated for its effect on the anticancer activity of cyclophosphamide in tumor-bearing animals. Therefore, there is a great necessity for adequate well-designed clinical studies for evaluation of the therapeutic values of these candidates. Conclusively, this review summarizes the molecular mechanisms accounting for cyclophosphamide-induced neurotoxicity together with the potential protective strategies seeking for downgrading this neurological complication, thus enhancing the quality of life and well-being of cancer patients treated with cyclophosphamide.

Schisandrin B alleviates angiotensin II-induced cardiac inflammatory remodeling by inhibiting the recruitment of MyD88 to TLRs in mouse cardiomyocytes

Cardiac tissue remodeling is characterized by altered heart tissue architecture and dysfunction, leading to heart failure. Sustained activation of the renin-angiotensin-aldosterone system (RAAS) greatly promotes the development of myocardial remodeling. Angiotensin II (Ang II), which is the major component of RAAS, can directly lead to cardiac remodeling by inducing an inflammatory response. Schisandrin B (Sch B), the active component extracted from the fruit of Schisandra chinensis (Turcz.) Baill has been shown to exhibit anti-inflammatory activity through its ability to target TLR4 and its adaptor protein, MyD88. In this study, we explored whether Sch B alleviates Ang II-induced myocardial inflammation and remodeling via targeting MyD88. Sch B significantly suppressed Ang II-induced inflammation as well as increased the expression of several genes of tissue remodeling (β-Mhc, Tgfb, Anp, α-Ska) both in vivo and in vitro. These protective effects of Sch B were due to the inhibition of recruitment of MyD88 to TLR2 and TLR4, suppressing the Ang II-induced NF-κB activation and reducing the following inflammatory responses. Moreover, the knockdown of Myd88 in cardiomyocytes abrogated the Ang II-induced increases in the production of inflammatory cytokines and expression of remodeling genes. These findings provide new evidence that the mechanism of Sch B protection was attributed to selective inhibition of MyD88 signaling. This finding could pave the way for novel therapeutic strategies for myocardial inflammatory diseases.

Interaction of antiphospholipid antibodies with endothelial cells in antiphospholipid syndrome

Antiphospholipid syndrome (APS) is an autoimmune disease with arteriovenous thrombosis and recurrent miscarriages as the main clinical manifestations. Due to the complexity of its mechanisms and the diversity of its manifestations, its diagnosis and treatment remain challenging issues. Antiphospholipid antibodies (aPL) not only serve as crucial "biomarkers" in diagnosing APS but also act as the "culprits" of the disease. Endothelial cells (ECs), as one of the core target cells of aPL, bridge the gap between the molecular level of these antibodies and the tissue and organ level of pathological changes. A more in-depth exploration of the relationship between ECs and the pathogenesis of APS holds the potential for significant advancements in the precise diagnosis, classification, and therapy of APS. Many researchers have highlighted the vital involvement of ECs in APS and the underlying mechanisms governing their functionality. Through extensive in vitro and in vivo experiments, they have identified multiple aPL receptors on the EC membrane and various intracellular pathways. This article furnishes a comprehensive overview and summary of these receptors and signaling pathways, offering prospective targets for APS therapy.

Toll-like receptor 4 signaling activation domains promote CAR T cell function against solid tumors

Chimeric antigen receptor (CAR) T cell therapy has emerged as a powerful therapeutic approach against a range of hematologic malignancies. While the incorporation of CD28 or 4-1BB costimulatory signaling domains into CARs revolutionized immune responses, there is an exciting prospect of further enhancing CAR functionality. Here, we investigated the design of CD19 CARs enriched with distinct Toll-like receptor 4 (TLR4), myeloid differentiation primary response 88 (MyD88), or Toll/IL-1 domain-containing adaptor-inducing interferon (IFN)-β (TRIF) costimulatory domains. Screening of various designs identified several candidates with no tonic activity but with increased CD19 target cell-dependent interleukin (IL)-2 production. Human T cells transduced with the selected CAR construct exhibited augmented hIL-2 and hIFN-γ induction and cytotoxicity when cocultured with CD19-positive lymphoma and solid-tumor cell lines. RNA sequencing (RNA-seq) analysis demonstrated the upregulation of some genes involved in the innate immune response and T cell activation and proliferation. In experiments on a xenogeneic solid-tumor mice model, MyD88 and TLR4 CAR T cells exhibited prolonged remission. This study demonstrates that the integration of a truncated TLR4 signaling costimulatory domain could provide immunotherapeutic potential against both hematologic malignancies and solid tumors.

Regulation of immune responses to infection through interaction between stem cell-derived exosomes and toll-like receptors mediated by microRNA cargoes

Infectious diseases are among the factors that account for a significant proportion of disease-related deaths worldwide. The primary treatment approach to combat microbial infections is the use of antibiotics. However, the widespread use of these drugs over the past two decades has led to the emergence of resistant microbial species, making the control of microbial infections a serious challenge. One of the most important solutions in the field of combating infectious diseases is the regulation of the host's defense system. Toll-like receptors (TLRs) play a crucial role in the first primary defense against pathogens by identifying harmful endogenous molecules released from dying cells and damaged tissues as well as invading microbial agents. Therefore, they play an important role in communicating and regulating innate and adaptive immunity. Of course, excessive activation of TLRs can lead to disruption of immune homeostasis and increase the risk of inflammatory reactions. Targeting TLR signaling pathways has emerged as a new therapeutic approach for infectious diseases based on host-directed therapy (HDT). In recent years, stem cell-derived exosomes have received significant attention as factors regulating the immune system. The regulation effects of exosomes on the immune system are based on the HDT strategy, which is due to their cargoes. In general, the mechanism of action of stem cell-derived exosomes in HDT is by regulating and modulating immunity, promoting tissue regeneration, and reducing host toxicity. One of their most important cargoes is microRNAs, which have been shown to play a significant role in regulating immunity through TLRs. This review investigates the therapeutic properties of stem cell-derived exosomes in combating infections through the interaction between exosomal microRNAs and Toll-like receptors.

Neuroactive Steroids, Toll-like Receptors, and Neuroimmune Regulation: Insights into Their Impact on Neuropsychiatric Disorders

Pregnane neuroactive steroids, notably allopregnanolone and pregnenolone, exhibit efficacy in mitigating inflammatory signals triggered by toll-like receptor (TLR) activation, thus attenuating the production of inflammatory factors. Clinical studies highlight their therapeutic potential, particularly in conditions like postpartum depression (PPD), where the FDA-approved compound brexanolone, an intravenous formulation of allopregnanolone, effectively suppresses TLR-mediated inflammatory pathways, predicting symptom improvement. Additionally, pregnane neurosteroids exhibit trophic and anti-inflammatory properties, stimulating the production of vital trophic proteins and anti-inflammatory factors. Androstane neuroactive steroids, including estrogens and androgens, along with dehydroepiandrosterone (DHEA), display diverse effects on TLR expression and activation. Notably, androstenediol (ADIOL), an androstane neurosteroid, emerges as a potent anti-inflammatory agent, promising for therapeutic interventions. The dysregulation of immune responses via TLR signaling alongside reduced levels of endogenous neurosteroids significantly contributes to symptom severity across various neuropsychiatric disorders. Neuroactive steroids, such as allopregnanolone, demonstrate efficacy in alleviating symptoms of various neuropsychiatric disorders and modulating neuroimmune responses, offering potential intervention avenues. This review emphasizes the significant therapeutic potential of neuroactive steroids in modulating TLR signaling pathways, particularly in addressing inflammatory processes associated with neuropsychiatric disorders. It advances our understanding of the complex interplay between neuroactive steroids and immune responses, paving the way for personalized treatment strategies tailored to individual needs and providing insights for future research aimed at unraveling the intricacies of neuropsychiatric disorders.

TRIF-dependent signaling and its role in liver diseases

TIR domain-containing adaptor inducing IFN-β (TRIF) is a crucial adaptor molecule downstream of toll-like receptors 3 (TLR3) and 4 (TLR4). TRIF directly binds to TLR3 through its TIR domain, while it associates with TLR4 indirectly through the bridge adaptor molecule TRIF-related adaptor molecule (TRAM). TRIF plays a pivotal role in regulating interferon beta 1 (IFN-β) response, nuclear factor kappa B (NF-κB) signaling, apoptosis, and necroptosis signaling mediated by TLR3 and TLR4. It accomplishes these by recruiting and activating various kinases or transcription factors via its distinct domains. In this review, we comprehensively summarize the TRIF-dependent signaling pathways mediated by TLR3 and TLR4, elucidating key target molecules and downstream pathways. Furthermore, we provide an overview of TRIF's impact on several liver disorders, including drug-induced liver injury, ischemia-reperfusion liver injury, autoimmune hepatitis, viral hepatitis, alcohol-associated liver disease (ALD), metabolic dysfunction-associated steatotic liver disease (MASLD) and metabolic dysfunction-associated steatohepatitis (MASH). We also explore its effects on liver steatosis, inflammation, fibrosis, and carcinogenesis. A comprehensive understanding of the TRIF-dependent signaling pathways, as well as the intricate relationship between TRIF and liver diseases, can facilitate the identification of potential drug targets and the development of novel and effective therapeutics against hepatic disorders.

Novel TLR4-Activating Vaccine Adjuvant Enhances the Production of Enterococcus faecium-binding Antibodies

Vaccines are one of the greatest achievements of modern medicine. Due to their safer profile, the latest investigations usually focus on subunit vaccines. However, the active component often needs to be coupled with an adjuvant to be effective and properly trigger an immune response. We are developing a new synthetic monosaccharide-based TLR4 agonist, such as glucosamine-derived compounds FP18 and FP20, as a potential vaccine adjuvant. In this study, we present a new FP20 derivative, FP20Hmp, with a hydroxylated ester linked to the glucosamine core. We show that the modification introduced improves the activity of the adjuvant and its solubility. This study presents the synthesis of FP20Hmp, its in vitro characterization, and in vivo activity while coupled with the ovalbumin antigen or in formulation with an enterococcal antigen. We show that FP20Hmp enables increased production of antigen-specific antibodies that bind to the whole bacterium.

Role of toll-like receptor in the pathogenesis of oral cancer

Toll-like receptors are important molecules of innate immunity. They are known as pattern recognition receptors. They recognise certain molecules known as pathogen-associated molecular pattern on a pathogen and release chemicals that causes inflammation. Toll-like receptors (TLR) help in the removal of the infected cell and thus stop the spread of infection and are being studied for their association with cancer. Oral carcinoma has emerged as a major problem of our country today; it is found ranks first in men and third in women. Toll-like receptors have been implicated in the development of cancer. Certain polymorphisms in toll-like receptor can make a cell more susceptible to develop oral cancer. The identification of toll-like receptors and the different genotypes that are involved in the development of cancer can be utilised for using them as biomarkers of the disease. The study revealed that toll-like receptors like TLR7 and TLR5 are found to have a role in suppression of oral cancer while toll-like receptors like TLR4 and TLR2 are found to be associated with the progression of oral cancer. Toll-like receptors can turn out as important target molecules in the future in designing therapeutic strategies for oral cancer.

B cells mediate lung ischemia/reperfusion injury by recruiting classical monocytes via synergistic B cell receptor/TLR4 signaling

Ischemia/reperfusion injury-mediated (IRI-mediated) primary graft dysfunction (PGD) adversely affects both short- and long-term outcomes after lung transplantation, a procedure that remains the only treatment option for patients suffering from end-stage respiratory failure. While B cells are known to regulate adaptive immune responses, their role in lung IRI is not well understood. Here, we demonstrated by intravital imaging that B cells are rapidly recruited to injured lungs, where they extravasate into the parenchyma. Using hilar clamping and transplant models, we observed that lung-infiltrating B cells produce the monocyte chemokine CCL7 in a TLR4-TRIF-dependent fashion, a critical step contributing to classical monocyte (CM) recruitment and subsequent neutrophil extravasation, resulting in worse lung function. We found that synergistic BCR-TLR4 activation on B cells is required for the recruitment of CMs to the injured lung. Finally, we corroborated our findings in reperfused human lungs, in which we observed a correlation between B cell infiltration and CM recruitment after transplantation. This study describes a role for B cells as critical orchestrators of lung IRI. As B cells can be depleted with currently available agents, our study provides a rationale for clinical trials investigating B cell-targeting therapies.

Neurosteroid [3α,5α]-3-hydroxy-pregnan-20-one enhances IL-10 production via endosomal TRIF-dependent TLR4 signaling pathway

Background

Previous studies demonstrated the inhibitory effect of allopregnanolone (3α,5α-THP) on the activation of inflammatory toll-like receptor 4 (TLR4) signals in RAW264.7 macrophages and the brains of selectively bred alcohol-preferring (P) rats. In the current study, we investigated the impact of 3α,5α-THP on the levels of IL-10 and activation of the TRIF-dependent endosomal TLR4 pathway.

Methods

The amygdala and nucleus accumbens (NAc) of P rats, which exhibit innately activated TLR4 pathways as well as RAW264.7 cells, were used. Enzyme-linked immunosorbent assays (ELISA) and immunoblotting assays were used to ascertain the effects of 3α,5α-THP on the TRIF-dependent endosomal TLR4 pathway and endosomes were isolated to examine translocation of TLR4 and TRIF. Additionally, we investigated the effects of 3α,5α-THP and 3α,5α-THDOC (0.1, 0.3, and 1.0 µM) on the levels of IL-10 in RAW264.7 macrophages. Finally, we examined whether inhibiting TRIF (using TRIF siRNA) in RAW264.7 cells altered the levels of IL-10.

Results

3α,5α-THP administration facilitated activation of the endosomal TRIF-dependent TLR4 pathway in males, but not female P rats. 3α,5α-THP increased IL-10 levels (+13.2 ± 6.5%) and BDNF levels (+21.1 ± 11.5%) in the male amygdala. These effects were associated with increases in pTRAM (+86.4 ± 28.4%), SP1 (+122.2 ± 74.9%), and PI(3)K-p110δ (+61.6 ± 21.6%), and a reduction of TIRAP (-13.7 ± 6.0%), indicating the activation of the endosomal TRIF-dependent TLR4 signaling pathway. Comparable effects were observed in NAc of these animals. Furthermore, 3α,5α-THP enhanced the accumulation of TLR4 (+43.9 ± 11.3%) and TRIF (+64.8 ± 32.8%) in endosomes, with no significant effect on TLR3 accumulation. Additionally, 3α,5α-THP facilitated the transition from early endosomes to late endosomes (increasing Rab7 levels: +35.8 ± 18.4%). In RAW264.7 cells, imiquimod (30 µg/mL) reduced IL-10 while 3α,5α-THP and 3α,5α-THDOC (0.1, 0.3, and 1.0 µM) restored IL-10 levels. To determine the role of the TRIF-dependent TLR4 signaling pathway in IL-10 production, the downregulation of TRIF (-62.9 ± 28.2%) in RAW264.7 cells led to a reduction in IL-10 levels (-42.3 ± 8.4%). TRIF (-62.9 ± 28.2%) in RAW264.7 cells led to a reduction in IL-10 levels (-42.3 ± 8.4%) and 3α,5α-THP (1.0 µM) no longer restored the reduced IL-10 levels.

Conclusion

The results demonstrate 3α,5α-THP enhancement of the endosomal TLR4-TRIF anti-inflammatory signals and elevations of IL-10 in male P rat brain that were not detected in female P rat brain. These effects hold significant implications for controlling inflammatory responses in both the brain and peripheral immune cells.

Proteomic profile of epidermal mucus from Labeo rohita reveals differentially abundant proteins after Aeromonas hydrophila infection

We report the proteomic profile of Epidermal Mucus (EM) from Labeo rohita and identified the differentially abundant proteins (DAPs) against Aeromonas hydrophila infection through label-free liquid chromatography-mass spectrometry (LC-MS/MS). Using discovery-based proteomics, a total of 2039 proteins were quantified in nontreated group and 1,328 proteins in the treated group, of which 114 were identified as DAPs in both the groups. Of the 114 DAPs, 68 proteins were upregulated and 46 proteins were downregulated in the treated group compared to nontreated group. Functional annotations of these DAPs shows their association with metabolism, cellular process, molecular process, cytoskeletal, stress, and particularly immune system. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis and Fisher's exact test between the two groups shows that most of the proteins were immune-related, which were significantly associated with the proteasome, phagosome, and Salmonella infection pathways. Overall, this study shows a basic and primary way for further functional research of the involvement of vitellogenin 2, alpha-2-macroglobulin-like protein, toll-like receptors (TLR-13), calpain, keratin-like proteins, and heat shock proteins against bacterial infection. Nonetheless, this first-ever comprehensive report of a proteomic sketch of EM from L. rohita after A. hydrophila infection provides systematic protein information to broadly understand the biological role of fish EM against bacterial infection.

Mesenchymal Stromal Cells Primed by Toll-like Receptors 3 and 4 Enhanced Anti-Inflammatory Effects against LPS-Induced Macrophages via Extracellular Vesicles

Although it has been suggested that toll-like receptor (TLR) 3 and TLR4 activation alters mesenchymal stromal cells (MSCs)' immunoregulatory function as anti- or pro-inflammatory phenotypes, we have previously confirmed that TLR4-primed hUCB-MSCs alleviate lung inflammation and tissue injury in an E. coli-induced acute lung injury (ALI) mouse model. Therefore, we hypothesized that strong stimulation of TLR3 or TLR4 prompts hUCB-MSCs to exhibit an anti-inflammatory phenotype mediated by extracellular vesicles (EVs). In this study, we compared the anti-inflammatory effect of TLR3-primed and TLR4-primed hUCB-MSCs against an LPS-induced ALI in vitro model by treating MSCs, MSC-derived conditioned medium (CM), and MSC-derived extracellular vesicles (EVs). LPS-induced rat primary alveolar macrophage and RAW 264.7 cells were treated with naïve, TLR3-, and TLR4-primed MSCs and their derived CM and EVs. Flow cytometry and ELISA were used to evaluate M1-M2 polarization of macrophages and pro-inflammatory cytokine levels, respectively. LPS-stimulated macrophages showed significantly increased pro-inflammatory cytokines compared to those of the normal control, and the percentage of M2 macrophage phenotype was predominantly low. In reducing the inflammatory cytokines and enhancing M2 polarization, TLR3- and TLR4-primed MSCs were significantly more effective than the naïve MSCs, and this finding was also observed with the treatment of MSC-derived CMs and EVs. No significant difference between the efficacy of TLR3- and TLR-primed MSCs was observed. Strong stimulation of TLR3- and TLR4-stimulated hUCB-MSCs significantly reduced pro-inflammatory cytokine secretion from LPS-induced macrophages and significantly enhanced the M2 polarization of macrophages. We further confirmed that TLR-primed MSC-derived EVs can exert anti-inflammatory and immunosuppressive effects alone comparable to MSC treatment. We hereby suggest that in the LPS-induced macrophage in vitro model, EVs derived from both TLR3 and TLR4-primed MSCs can be a therapeutic candidate by promoting the M2 phenotype.

B Cells Induce Early-Onset Maternal Inflammation to Protect against LPS-Induced Fetal Rejection

The maternal balance between B regulatory (Breg) cells and inflammatory B cells is of central importance for protection against preterm birth (PTB). However, the impact of B cell signaling in early maternal and fetal immune responses on inflammatory insults remains underinvestigated. To understand which role B cells and B-cell-specific signaling play in the pathogenesis of PTB, the later was induced by an injection of LPS in B cell-sufficient WT mice, CD19-/-, BMyD88-/- and µMT murine dams at gestational day 16 (gd 16). WT dams developed a strong inflammatory response in their peritoneal cavity (PC), with an increased infiltration of granulocytes and enhanced IL-6, TNF-α, IL-17 and MCP-1 levels. However, they demonstrated a reduced NOS2 expression of PC macrophages 4 h after the LPS injection. Simultaneously, LPS-challenged WT dams upregulated pregnancy-protective factors like IL-10 and TARC. The concentrations of inflammatory mediators in the placental supernatants, amniotic fluids, fetal serums and gestational tissues were lower in LPS-challenged WT dams compared to CD19-/-, BMyD88-/- and µMT dams, thereby protecting WT fetuses from being born preterm. B cell deficiency, or the loss of B-cell-specific CD19 or MyD88 expression, resulted in an early shift from immune regulation towards inflammation at the fetomaternal interface and fetuses, resulting in PTB.

Emerging nanotherapeutic strategies targeting gut-X axis against diseases

Gut microbiota can coordinate with different tissues and organs to maintain human health, which derives the concept of the gut-X axis. Conversely, the dysbiosis of gut microbiota leads to the occurrence and development of various diseases, such as neurological diseases, liver diseases, and even cancers. Therefore, the modulation of gut microbiota offers new opportunities in the field of medicines. Antibiotics, probiotics or other treatments might restore unbalanced gut microbiota, which effects do not match what people have expected. Recently, nanomedicines with the high targeting ability and reduced toxicity make them an appreciative choice for relieving disease through targeting gut-X axis. Considering this paradigm-setting trend, the current review summarizes the advancements in gut microbiota and its related nanomedicines. Specifically, this article introduces the immunological effects of gut microbiota, summarizes the gut-X axis-associated diseases, and highlights the nanotherapeutics-mediated treatment via remolding the gut-X axis. Moreover, this review also discusses the challenges in studies related to nanomedicines targeting the gut microbiota and offers the future perspective, thereby aiming at charting a course toward clinic.

Toll-like receptor 4: A potential therapeutic target for multiple human diseases

The immune response plays a pivotal role in the pathogenesis of diseases. Toll-like receptor 4 (TLR4), as an intrinsic immune receptor, exhibits widespread in vivo expression and its dysregulation significantly contributes to the onset of various diseases, encompassing cardiovascular disorders, neoplastic conditions, and inflammatory ailments. This comprehensive review centers on elucidating the architectural and distributive characteristics of TLR4, its conventional signaling pathways, and its mode of action in diverse disease contexts. Ultimately, this review aims to propose novel avenues and therapeutic targets for clinical intervention.

HMGB1 and Toll-like receptors: potential therapeutic targets in autoimmune diseases

HMGB1, a nucleoprotein, is expressed in almost all eukaryotic cells. During cell activation and cell death, HMGB1 can function as an alarm protein (alarmin) or damage-associated molecular pattern (DAMP) and mediate early inflammatory and immune response when it is translocated to the extracellular space. The binding of extracellular HMGB1 to Toll-like receptors (TLRs), such as TLR2 and TLR4 transforms HMGB1 into a pro-inflammatory cytokine, contributing to the occurrence and development of autoimmune diseases. TLRs, which are members of a family of pattern recognition receptors, can bind to endogenous DAMPs and activate the innate immune response. Additionally, TLRs are key signaling molecules mediating the immune response and play a critical role in the host defense against pathogens and the maintenance of immune balance. HMGB1 and TLRs are reported to be upregulated in several autoimmune diseases, such as rheumatoid arthritis, systemic lupus erythematosus, type 1 diabetes mellitus, and autoimmune thyroid disease. The expression levels of HMGB1 and some TLRs are upregulated in tissues of patients with autoimmune diseases and animal models of autoimmune diseases. The suppression of HMGB1 and TLRs inhibits the progression of inflammation in animal models. Thus, HMGB1 and TLRs are indispensable biomarkers and important therapeutic targets for autoimmune diseases. This review provides comprehensive strategies for treating or preventing autoimmune diseases discovered in recent years.

TLR3/TRIF pathway confers protection against herpes simplex encephalitis through NK cell activation mediated by a loop of type I IFN and IL-15 from epithelial and dendritic cells

Autosomal recessive (AR) and dominant (AD) deficiencies of TLR3 and TRIF are believed to be crucial genetic causes of herpes simplex encephalitis (HSE), which is a fatal disease causing focal or global cerebral dysfunction following infection with herpes simplex virus type 1 (HSV-1). However, few studies have been conducted on the immunopathological networks of HSE in the context of TLR3 and TRIF defects at the cellular and molecular levels. In this work, we deciphered the crosstalk between type I IFN (IFN-I)-producing epithelial layer and IL-15-producing dendritic cells (DC) to activate NK cells for the protective role of TLR3/TRIF pathway in HSE progression after vaginal HSV-1 infection. TLR3- and TRIF-ablated mice showed enhanced susceptibility to HSE progression, along with high HSV-1 burden in vaginal tract, lymphoid tissues and CNS. The increased HSV-1 burden in TLR3- and TRIF-ablated mice did not correlate with increased infiltration of Ly-6C+ monocytes, but it was closely associated with impaired NK cell activation in vaginal tract. Furthermore, using delicate ex vivo experiments and bone marrow transplantation, TRIF deficiency in tissue-resident cells, such as epithelial cells in vaginal tract, was found to cause impaired NK cell activation by means of low IFN-I production, whereas IFN-I receptor in DC was required for NK cell activation via IL-15 production in response to IFN-I produced from epithelial layer. These results provide new information about IFN-I- and IL-15-mediated crosstalk between epithelial cells and DC at the primary infection site, which suppresses HSE progression in a TLR3- and TRIF-dependent manner.

Interferons-Implications in the Immune Response to Respiratory Viruses

Interferons (IFN) are an assemblage of signaling proteins made and released by various host cells in response to stimuli, including viruses. Respiratory syncytial virus (RSV), influenza virus, and SARS-CoV-2 are major causes of respiratory disease that induce or antagonize IFN responses depending on various factors. In this review, the role and function of type I, II, and III IFN responses to respiratory virus infections are considered. In addition, the role of the viral proteins in modifying anti-viral immunity is noted, as are the specific IFN responses that underly the correlates of immunity and protection from disease.

Anti-Inflammatory Effect of Meriania hexamera Sprague by Targeting Syk Kinase in NF-κB Signaling

Inflammation is a protective mechanism against harmful stimuli. There are two types of inflammation, acute and chronic, and severe diseases such as cardiovascular disease and cancer can be caused by chronic inflammation. Therefore, this research was conducted to discover new anti-inflammatory drugs. Meriania hexamera Sprague is a common herb in the Amazon region in South America. It is used as a traditional medical herb by natives, but no studies to date have investigated its anti-inflammatory activity. Using lipopolysaccharide (LPS), pam3CSK4 (Pam3), and poly(I:C), we studied the M. hexamera Sprague-Methanol Extract's (Mh-ME) in vitro anti-inflammatory functions. Using RAW264.7 cells, we detected the released nitric oxide (NO) and mRNA expression extent of inducible nitric oxide synthase (iNOS) with pro-inflammatory proteins like tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and iterleukin-1 beta (IL-1β). It was found that Mh-ME suppressed the inflammatory activities in a dose-dependent manner. In the luciferase assay, the nuclear factor kappa light chain enhancer of the activated B cells (NF-κB) pathway was inhibited by Mh-ME. Mh-ME especially acted as an inhibitor of Syk kinase according to the results from CETSA. We also confirmed that Mh-ME mitigates acute gastritis derived from HCl/EtOH in ICR mice, ameliorating the expression of IL-1β and tumor necrosis factor-alpha (TNF-α). In conclusion, Mh-ME is an herb with anti-inflammatory effects that targets Syk in the NF-κB pathway, suggesting that Mh-ME could be used as an anti-inflammatory herbal medicine.

Airway Epithelial-Derived Immune Mediators in COVID-19

The airway epithelium, which lines the conducting airways, is central to the defense of the lungs against inhaled particulate matter and pathogens such as SARS-CoV-2, the virus that causes COVID-19. Recognition of pathogens results in the activation of an innate and intermediate immune response which involves the release of cytokines and chemokines by the airway epithelium. This response can inhibit further viral invasion and influence adaptive immunity. However, severe COVID-19 is characterized by a hyper-inflammatory response which can give rise to clinical presentations including lung injury and lead to acute respiratory distress syndrome, viral pneumonia, coagulopathy, and multi-system organ failure. In response to SARS-CoV-2 infection, the airway epithelium can mount a maladaptive immune response which can delay viral clearance, perpetuate excessive inflammation, and contribute to the pathogenesis of severe COVID-19. In this article, we will review the barrier and immune functions of the airway epithelium, how SARS-CoV-2 can interact with the epithelium, and epithelial-derived cytokines and chemokines and their roles in COVID-19 and as biomarkers. Finally, we will discuss these immune mediators and their potential as therapeutic targets in COVID-19.

Role of innate immunological/inflammatory pathways in myelodysplastic syndromes and AML: a narrative review

Dysregulation of the innate immune system and inflammatory-related pathways has been implicated in hematopoietic defects in the bone marrow microenvironment and associated with aging, clonal hematopoiesis, myelodysplastic syndromes (MDS), and acute myeloid leukemia (AML). As the innate immune system and its pathway regulators have been implicated in the pathogenesis of MDS/AML, novel approaches targeting these pathways have shown promising results. Variability in expression of Toll like receptors (TLRs), abnormal levels of MyD88 and subsequent activation of NF-κβ, dysregulated IL1-receptor associated kinases (IRAK), alterations in TGF-β and SMAD signaling, high levels of S100A8/A9 have all been implicated in pathogenesis of MDS/AML. In this review we not only discuss the interplay of various innate immune pathways in MDS pathogenesis but also focus on potential therapeutic targets from recent clinical trials including the use of monoclonal antibodies and small molecule inhibitors against these pathways.

Hypoxia-altered cholesterol homeostasis enhances the expression of interferon-stimulated genes upon SARS-CoV-2 infections in monocytes

Hypoxia contributes to numerous pathophysiological conditions including inflammation-associated diseases. We characterized the impact of hypoxia on the immunometabolic cross-talk between cholesterol and interferon (IFN) responses. Specifically, hypoxia reduced cholesterol biosynthesis flux and provoked a compensatory activation of sterol regulatory element-binding protein 2 (SREBP2) in monocytes. Concomitantly, a broad range of interferon-stimulated genes (ISGs) increased under hypoxia in the absence of an inflammatory stimulus. While changes in cholesterol biosynthesis intermediates and SREBP2 activity did not contribute to hypoxic ISG induction, intracellular cholesterol distribution appeared critical to enhance hypoxic expression of chemokine ISGs. Importantly, hypoxia further boosted chemokine ISG expression in monocytes upon infection with severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2). Mechanistically, hypoxia sensitized toll-like receptor 4 (TLR4) signaling to activation by SARS-CoV-2 spike protein, which emerged as a major signaling hub to enhance chemokine ISG induction following SARS-CoV-2 infection of hypoxic monocytes. These data depict a hypoxia-regulated immunometabolic mechanism with implications for the development of systemic inflammatory responses in severe cases of coronavirus disease-2019 (COVID-19).

Molecular Mechanisms for the Vicious Cycle between Insulin Resistance and the Inflammatory Response in Obesity

The comprehensive anabolic effects of insulin throughout the body, in addition to the control of glycemia, include ensuring lipid homeostasis and anti-inflammatory modulation, especially in adipose tissue (AT). The prevalence of obesity, defined as a body mass index (BMI) ≥ 30 kg/m², has been increasing worldwide on a pandemic scale with accompanying syndemic health problems, including glucose intolerance, insulin resistance (IR), and diabetes. Impaired tissue sensitivity to insulin or IR paradoxically leads to diseases with an inflammatory component despite hyperinsulinemia. Therefore, an excess of visceral AT in obesity initiates chronic low-grade inflammatory conditions that interfere with insulin signaling via insulin receptors (INSRs). Moreover, in response to IR, hyperglycemia itself stimulates a primarily defensive inflammatory response associated with the subsequent release of numerous inflammatory cytokines and a real threat of organ function deterioration. In this review, all components of this vicious cycle are characterized with particular emphasis on the interplay between insulin signaling and both the innate and adaptive immune responses related to obesity. Increased visceral AT accumulation in obesity should be considered the main environmental factor responsible for the disruption in the epigenetic regulatory mechanisms in the immune system, resulting in autoimmunity and inflammation.

Efficiency of Interferon-γ in Activating Dendritic Cells and Its Potential Synergy with Toll-like Receptor Agonists

Interferon-γ (IFN-γ) is a cytokine that plays an important role in immune regulation, especially in the activation and differentiation of immune cells. Toll-like receptors (TLRs) are a family of pattern-recognition receptors that sense structural motifs related to pathogens and alert immune cells to the invasion. Both IFN-γ and TLR agonists have been used as immunoadjuvants to augment the efficacy of cancer immunotherapies and vaccines against infectious diseases or psychoactive compounds. In this study, we aimed to explore the potential of IFN-γ and TLR agonists being applied simultaneously to boost dendritic cell activation and the subsequent antigen presentation. In brief, murine dendritic cells were treated with IFN-γ and/or the TLR agonists, polyinosinic-polycytidylic acid (poly I:C), or resiquimod (R848). Next, the dendritic cells were stained for an activation marker, a cluster of differentiation 86 (CD86), and the percentage of CD86-positive cells was measured by flow cytometry. From the cytometric analysis, IFN-γ efficiently stimulated a considerable number of the dendritic cells, while the TLR agonists by themselves could merely activate a few compared to the control. The combination of IFN-γ with poly I:C or R848 triggered a higher amount of dendritic cell activation than IFN-γ alone. For instance, 10 ng/mL IFN-γ with 100 µg/mL poly I:C achieved 59.1% cell activation, which was significantly higher than the 33.4% CD86-positive cells obtained by 10 ng/mL IFN-γ. These results suggested that IFN-γ and TLR agonists could be applied as complementary systems to promote dendritic cell activation and antigen presentation. There might be a synergy between the two classes of molecules, but further investigation is warranted to ascertain the interaction of their promotive activities.

Long noncoding RNA LTCONS6801 up-regulates TBK1 mediated antiviral innate immunity in miiuy croaker, Miichttys miiuy

The development of seuencing technology has further accelerated the research of noncoding RNA (ncRNA). A large number of studies have shown that long noncoding RNA (lncRNA) in ncRNA can regulate gene expression in various ways and then affect various physiological and biochemical processes of the host. In this study, we found a novel lncRNA in Miichthys miiuy, named LTCONS6801, which is beneficial to TANK-binding kinase 1 (TBK1) and its -mediated pathway to promote the host immune function. First, we found that lncRNA LTCONS6801 can enhance cell activity through cell activity detection and cell proliferation detection. Besides, after poly (I: C) stimulation, overexpression of lncRNA LTCONS6801 promoted the expression of antiviral gene and TBK1. We found that lncRNA LTCONS6801 further affects NF-κB and IRF3 signaling pathways by regulating the expression of TBK1. In short, lncRNA LTCONS6801 is an lncRNA that can positively regulate the host innate immune response by regulating the expression of TBK1. Our study enriches the theory and insight of lncRNA regulating antiviral immune pathway and clarifies the important role of lncRNA in antiviral immunity of teleost fish.

The balance between gasdermin D and STING signaling shapes the severity of schistosome immunopathology

There is significant disease heterogeneity among mouse strains infected with the helminth Schistosoma mansoni. Here, we uncover a unique balance in two critical innate pathways governing the severity of disease. In the low-pathology setting, parasite egg-stimulated dendritic cells (DCs) induce robust interferon (IFN)β production, which is dependent on the cyclic GMP-AMP synthase (cGAS)/stimulator of interferon genes (STING) cytosolic DNA sensing pathway and results in a Th2 response with suppression of proinflammatory cytokine production and Th17 cell activation. IFNβ induces signal transducer and activator of transcription (STAT)1, which suppresses CD209a, a C-type lectin receptor associated with severe disease. In contrast, in the high-pathology setting, enhanced DC expression of the pore-forming protein gasdermin D (Gsdmd) results in reduced expression of cGAS/STING, impaired IFNβ, and enhanced pyroptosis. Our findings demonstrate that cGAS/STING signaling represents a unique mechanism inducing protective type I IFN, which is counteracted by Gsdmd.

Proteomic analysis of liver tissue reveals Aeromonas hydrophila infection mediated modulation of host metabolic pathways in Labeo rohita

Aeromonas hydrophila (Ah) is a Gram-negative bacterium and a serious global pathogen causing Motile Aeromonas Septicaemia (MAS) in fish leading to global loss in aquaculture. Investigation of the molecular alterations of host tissues such as liver could be a powerful approach to identify mechanistic and diagnostic immune signatures of disease pathogenesis. We performed a proteomic analysis of Labeo rohita liver tissue to examine the protein dynamics in the host cells during Ah infection. The proteomic data was acquired using two strategies; discovery and targeted proteomics. Label-free quantification was performed between Control and challenged group (AH) to identify the differentially expressed proteins (DEPs). A total of 2525 proteins were identified and 157 were DEPs. DEPs include metabolic enzymes (CS, SUCLG2), antioxidative proteins, cytoskeletal proteins and immune related proteins (TLR3, CLEC4E). Pathways like lysosome pathway, apoptosis, metabolism of xenobiotics by cytochrome P450 were enriched by downregulated proteins. However, upregulated proteins majorly mapped to innate immune system, signaling of B cell receptor, proteosome pathway, ribosome, carbon metabolism and protein processing in ER. Our study would help in exploring the role of Toll-like receptors, C-type lectins and, metabolic intermediates like citrate and succinate in Ah pathogenesis to understand the Ah infection in fish. SIGNIFICANCE: Bacterial diseases such as motile aeromonas septicaemia (MAS) are among the most serious problems in aquaculture industry. Small molecules that target the metabolism of the host have recently emerged as potential treatment possibilities in infectious diseases. However, the ability to develop new therapies is hampered due to lack of knowledge about pathogenesis mechanisms and host-pathogen interactions. We examined alterations in the host proteome during MAS caused by Aeromonas hydrophila (Ah) infection, in Labeo rohita liver tissue to find cellular proteins and processes affected by Ah infection. Upregulated proteins belong to innate immune system, signaling of B cell receptor, proteosome pathway, ribosome, carbon metabolism and protein processing. Our work is an important step towards leveraging host metabolism in targeting the disease by providing a bigger picture on proteome pathology correlation during Ah infection.

Role of Plant-Derived Compounds in the Molecular Pathways Related to Inflammation

Inflammation is the primary response to infection and injury. Its beneficial effect is an immediate resolution of the pathophysiological event. However, sustained production of inflammatory mediators such as reactive oxygen species and cytokines may cause alterations in DNA integrity and lead to malignant cell transformation and cancer. More attention has recently been paid to pyroptosis, which is an inflammatory necrosis that activates inflammasomes and the secretion of cytokines. Taking into consideration that phenolic compounds are widely available in diet and medicinal plants, their role in the prevention and support of the treatment of chronic diseases is apparent. Recently, much attention has been paid to explaining the significance of isolated compounds in the molecular pathways related to inflammation. Therefore, this review aimed to screen reports concerning the molecular mode of action assigned to phenolic compounds. The most representative compounds from the classes of flavonoids, tannins, phenolic acids, and phenolic glycosides were selected for this review. Our attention was focused mainly on nuclear factor-κB (NF-κB), nuclear factor erythroid 2-related factor 2 (Nrf2), and mitogen-activated protein kinase (MAPK) signaling pathways. Literature searching was performed using Scopus, PubMed, and Medline databases. In conclusion, based on the available literature, phenolic compounds regulate NF-κB, Nrf2, and MAPK signaling, which supports their potential role in chronic inflammatory disorders, including osteoarthritis, neurodegenerative diseases, cardiovascular, and pulmonary disorders.

Toll-like Receptor 4 in Acute Kidney Injury

Acute kidney injury (AKI) is a common and devastating pathologic condition, associated with considerable high morbidity and mortality. Although significant breakthroughs have been made in recent years, to this day no effective pharmacological therapies for its treatment exist. AKI is known to be connected with intrarenal and systemic inflammation. The innate immune system plays an important role as the first defense response mechanism to tissue injury. Toll-like receptor 4 (TLR4) is a well-characterized pattern recognition receptor, and increasing evidence has shown that TLR4 mediated inflammatory response, plays a pivotal role in the pathogenesis of acute kidney injury. Pathogen-associated molecular patterns (PAMPS), which are the conserved microbial motifs, are sensed by these receptors. Endogenous molecules generated during tissue injury, and labeled as damage-associated molecular pattern molecules (DAMPs), also activate pattern recognition receptors, thereby offering an understanding of sterile types of inflammation. Excessive, uncontrolled and/or sustained activation of TLR4, may lead to a chronic inflammatory state. In this review we describe the role of TLR4, its endogenous ligands and activation in the inflammatory response to ischemic/reperfusion-induced AKI and sepsis-associated AKI. The potential regeneration signaling patterns of TLR4 in acute kidney injury, are also discussed.

Therapeutic immunomodulation by rationally designed nucleic acids and nucleic acid nanoparticles

The immune system has evolved to defend organisms against exogenous threats such as viruses, bacteria, fungi, and parasites by distinguishing between "self" and "non-self". In addition, it guards us against other diseases, such as cancer, by detecting and responding to transformed and senescent cells. However, for survival and propagation, the altered cells and invading pathogens often employ a wide range of mechanisms to avoid, inhibit, or manipulate the immunorecognition. As such, the development of new modes of therapeutic intervention to augment protective and prevent harmful immune responses is desirable. Nucleic acids are biopolymers essential for all forms of life and, therefore, delineating the complex defensive mechanisms developed against non-self nucleic acids can offer an exciting avenue for future biomedicine. Nucleic acid technologies have already established numerous approaches in therapy and biotechnology; recently, rationally designed nucleic acids nanoparticles (NANPs) with regulated physiochemical properties and biological activities has expanded our repertoire of therapeutic options. When compared to conventional therapeutic nucleic acids (TNAs), NANP technologies can be rendered more beneficial for synchronized delivery of multiple TNAs with defined stabilities, immunological profiles, and therapeutic functions. This review highlights several recent advances and possible future directions of TNA and NANP technologies that are under development for controlled immunomodulation.

Harmine Inhibits Multiple TLR-Induced Inflammatory Expression through Modulation of NF-κB p65, JNK, and STAT1

Harmine is a beta-carboline alkaloid present in various plants, including in the seeds of Peganum harmala L. This study aimed to investigate the anti-inflammatory activity and mechanism of harmine using macrophages stimulated with various toll-like receptor (TLR) agonists and a model of endotoxemia. The expression of inflammatory mediators induced by ligands of TLRs 2, 3, 4, and 9 were examined in thioglycollate-elicited peritoneal macrophages isolated from BALB/c and C57BL/6 mouse strains. Further, the activation of NF-κB, MAPK, AP-1, and STAT1 was explored using lipopolysaccharide (LPS) and polyinosinic:polycytidylic acid (poly(I:C)). Finally, the liver inflammatory response during endotoxemia was examined. Harmine inhibited inducible nitric oxide synthase, cyclooxygenase-2 (COX-2), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), IL-12, and other markers induced by various TLR agonists. The inhibition of NF-κB activity by harmine occurred via the modulation of p65 phosphorylation, independent of IκBα degradation. The inhibition of AP-1 activity by harmine was associated with the modulation of JNK. Harmine inhibited the LPS-induced serine and tyrosine phosphorylation of STAT1, but only affected serine phosphorylation by poly(I:C) treatment. In vivo, harmine inhibited iNOS and COX-2 expression during endotoxemia. Collectively, the results show that harmine can be effective against infectious inflammation through modulation of NF-κB, JNK, and STAT1.

Palmitic Acid Promotes Lung Metastasis of Melanomas via the TLR4/TRIF-Peli1-pNF-κB Pathway

A high-fat diet plays an important role in aggravating cancers. Palmitic acid (PA) is one of the components of saturated fatty acids; it has been reported to promote tumor proliferation in melanomas, but the signal transduction pathway mediated by palmitic acid remains unclear. This study showed that palmitic acid can promote the lung metastasis of melanomas. Moreover, the interaction between palmitic acid and toll-like receptor 4 (TLR4) was predicted by molecular docking. The experimental results proved that palmitic acid could promote the TLR4 and Toll/IL-1 receptor domain-containing adaptor-inducing IFN-β (TRIF) expression. The expression of Pellino1 (Peli1) and the phosphorylation of NF-kappa B (pNF-κB) were downregulated after the suppression of TLR4 and the silencing of Peli1 also inhibited the phosphorylation of NF-κB. Therefore, we concluded that palmitic acid promoted the lung metastasis of melanomas through the TLR4/TRIF-Peli1-pNF-κB pathway.

Bioactive compounds modulating Toll-like 4 receptor (TLR4)-mediated inflammation: pathways involved and future perspectives

Chronic inflammation is associated with the development and progression of several noncommunicable diseases, such as diabetes, cardiovascular disease, chronic kidney disease, cancer, and nonalcoholic fatty liver disease. Evidence suggests that pattern recognition receptors that identify pathogen-associated molecular patterns and danger-associated molecular patterns are crucial in chronic inflammation. Among the pattern recognition receptors, Toll-like receptor 4 (TLR4) stimulates several inflammatory pathway agonists, such as nuclear factor-κB, interferon regulator factor 3, and nod-like receptor pyrin domain containing 3 pathways, which consequently trigger the expression of pro-inflammatory biomarkers, increasing the risk of noncommunicable disease development and progression. Studies have focused on the antagonistic potential of bioactive compounds, following the concept of food as a medicine, in which nutritional strategies may mitigate inflammation via TLR4 modulation. Thus, this review discusses preclinical evidence concerning bioactive compounds from fruit, vegetable, spice, and herb extracts (curcumin, resveratrol, catechin, cinnamaldehyde, emodin, ginsenosides, quercetin, allicin, and caffeine) that may regulate the TLR4 pathway and reduce the inflammatory response. Bioactive compounds can inhibit TLR4-mediated inflammation through gut microbiota modulation, improvement of intestinal permeability, inhibition of lipopolysaccharide-TLR4 binding, and decreasing TLR4 expression by modulation of microRNAs and antioxidant pathways. The responses directly mitigated inflammation, especially nuclear factor-κB activation and inflammatory cytokines release. These findings should be considered for further clinical studies on inflammation-mediated diseases.

Major pathways involved in macrophage polarization in cancer

Macrophages play an important role in tissue homeostasis, tissue remodeling, immune response, and progression of cancer. Consequently, macrophages exhibit significant plasticity and change their transcriptional profile and function in response to environmental, tissue, and inflammatory stimuli resulting in pro- and anti-tumor effects. Furthermore, the categorization of tissue macrophages in inflammatory situations remains difficult; however, there is an agreement that macrophages are predominantly polarized into two different subtypes with pro- and anti-inflammatory properties, the so-called M1-like and M2-like macrophages, respectively. These two macrophage classes can be considered as the extreme borders of a continuum of many intermediate subsets. On one end, M1 are pro-inflammatory macrophages that initiate an immunological response, damage tissue integrity, and dampen tumor progression by fostering robust T and natural killer (NK) cell anti-tumoral responses. On the other end, M2 are anti-inflammatory macrophages involved in tissue remodeling and tumor growth, that promote cancer cell proliferation, invasion, tumor metastasis, angiogenesis and that participate to immune suppression. These decisive roles in tumor progression occur through the secretion of cytokines, chemokines, growth factors, and matrix metalloproteases, as well as by the expression of immune checkpoint receptors in the case of M2 macrophages. Moreover, macrophage plasticity is supported by stimuli from the Tumor Microenvironment (TME) that are relayed to the nucleus through membrane receptors and signaling pathways that result in gene expression reprogramming in macrophages, thus giving rise to different macrophage polarization outcomes. In this review, we will focus on the main signaling pathways involved in macrophage polarization that are activated upon ligand-receptor recognition and in the presence of other immunomodulatory molecules in cancer.

The lncRNA ALPHA specifically targets chikungunya virus to control infection

Arthropod-borne viruses, including the alphavirus chikungunya virus (CHIKV), cause acute disease in millions of people and utilize potent mechanisms to antagonize and circumvent innate immune pathways including the type I interferon (IFN) pathway. In response, hosts have evolved antiviral counterdefense strategies that remain incompletely understood. Recent studies have found that long noncoding RNAs (lncRNAs) regulate classical innate immune pathways; how lncRNAs contribute to additional antiviral counterdefenses remains unclear. Using high-throughput genetic screening, we identified a cytoplasmic antiviral lncRNA that we named antiviral lncRNA prohibiting human alphaviruses (ALPHA), which is transcriptionally induced by alphaviruses and functions independently of IFN to inhibit the replication of CHIKV and its closest relative, O'nyong'nyong virus (ONNV), but not other viruses. Furthermore, we showed that ALPHA interacts with CHIKV genomic RNA and restrains viral RNA replication. Together, our findings reveal that ALPHA and potentially other lncRNAs can mediate non-canonical antiviral immune responses against specific viruses.

Identification of quantitative trait loci for survival in the mutant dynactin p150Glued mouse model of motor neuron disease

Amyotrophic lateral sclerosis (ALS) is the most common degenerative motor neuron disorder. Although most cases of ALS are sporadic, 5-10% of cases are familial, with mutations associated with over 40 genes. There is variation of ALS symptoms within families carrying the same mutation; the disease may develop in one sibling and not in another despite the presence of the mutation in both. Although the cause of this phenotypic variation is unknown, it is likely related to genetic modifiers of disease expression. The identification of ALS causing genes has led to the development of transgenic mouse models of motor neuron disease. Similar to families with familial ALS, there are background-dependent differences in disease phenotype in transgenic mouse models of ALS suggesting that, as in human ALS, differences in phenotype may be ascribed to genetic modifiers. These genetic modifiers may not cause ALS rather their expression either exacerbates or ameliorates the effect of the mutant ALS causing genes. We have reported that in both the G93A-hSOD1 and G59S-hDCTN1 mouse models, SJL mice demonstrated a more severe phenotype than C57BL6 mice. From reciprocal intercrosses between G93A-hSOD1 transgenic mice on SJL and C57BL6 strains, we identified a major quantitative trait locus (QTL) on mouse chromosome 17 that results in a significant shift in lifespan. In this study we generated reciprocal intercrosses between transgenic G59S-hDCTN1 mice on SJL and C57BL6 strains and identified survival QTLs on mouse chromosomes 17 and 18. The chromosome 17 survival QTL on G93A-hSOD1 and G59S-hDCTN1 mice partly overlap, suggesting that the genetic modifiers located in this region may be shared by these two ALS models despite the fact that motor neuron degeneration is caused by mutations in different proteins. The overlapping region contains eighty-seven genes with non-synonymous variations predicted to be deleterious and/or damaging. Two genes in this segment, NOTCH3 and Safb/SAFB1, have been associated with motor neuron disease. The identification of genetic modifiers of motor neuron disease, especially those modifiers that are shared by SOD1 and dynactin-1 transgenic mice, may result in the identification of novel targets for therapies that can alter the course of this devastating illness.

Bifurcation of signalling in human innate immune pathways to NF-kB and IRF family activation

The human innate immune response can be activated through a wide range of stimuli. This multi-faceted system can be triggered by a range of immunostimulants including pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs). These stimuli drive intracellular signalling pathways that branch off downstream to activate several distinct transcription factors. The two most impactful of which in innate immune outcomes are the NF-κB and the IRF family members. Both transcription factor families play defining roles in driving inflammation as well as the antiviral response. Pathways leading to their simultaneous activation share common upstream components but eventually distinct regulators which directly facilitate their activation. This review will discuss the current state of knowledge about what is known about how these pathways bifurcate to activate NF-κB and IRF family members.

Delivery of antigen to porcine dendritic cells by fusing antigen with porcine dendritic cells targeting peptide

Dendritic cells (DCs) are professional antigen-presenting cells that can recognize, capture, and process antigens. Fusing molecules targeting DCs with antigens can effectively improve the efficiency with which antigens are recognized and captured by DCs. This targeting strategy can be used for vaccine development to effectively improve the efficiency of antigen recognition and capture by DCs. The targeting sequence of porcine cytotoxic T-lymphocyte associated protein 4 (CTLA4), which binds porcine DCs, was identified in this study. Recombinant Lactobacillus reuteri (L. reuteri) expressing CTLA4-6aa (LYPPPY) and CTLA4-87aa fused to the porcine epidemic diarrhea virus (PEDV) protective antigen core neutralizing epitope (COE) were used to evaluate the ability of the two targeting motifs to bind the B7 molecule on DCs. Our results demonstrate that CTLA4-6aa could bind porcine DCs, and recombinant Lactobacillus expressing the CTLA4-6aa captured by porcine DCs was more efficient than those expressing CTLA4-87aa. In addition, the expression of DC markers, toll-like receptors, and cytokines was significantly higher in the 6aa-COE/L. reuteri-stimulated porcine DCs compared to DCs treated with 87aa-COE/L. reuteri (p<0.01) and recombinant Lactobacillus expressing CTLA4-6aa enhanced the ability of porcine DCs to activate T-cell proliferation. Our analysis of the protein structure revealed that CTLA4-87aa contains intramolecular hydrogen bonds, which may have weakened the intermolecular force between the residues on porcine CTLA4 and that on B7. In conclusion, recombinant Lactobacillus expressing CTLA4-6aa were more efficiently captured by porcine DCs and had a stronger ability to promote DC maturation and enhance T-cell proliferation. The LYPPPY motif is the optimal sequence for binding to porcine DCs. Piglets immunized with recombinant Lactobacillus showed that recombinant Lactobacillus expressing CTLA4-6aa induced significant levels of anti-PEDV-specific IgG and IgA antibody responses. Our study may promote research on DC-targeting strategies to enhance the effectiveness of porcine vaccines.

Downregulated TICAM1 is a prognostic biomarker and associated with immune tolerance of Wilms tumor patients

Background

TIR domain containing adaptor molecule 1 (TICAM1) is a coding gene participating in immune and inflammation responses to malignant cells. However, the role of TICAM1 in Wilms tumor (WT) is rarely known.

Materials and methods

The expression level of TICAM1 was calculated in the WT TARGET cohort and validated using the GSE66405 cohort. The Kaplan–Meier method was employed to investigate the potential clinical value of TICAM1 and the association between its expression level and clinical features. The influence of TICAM1 on immune infiltration was examined by ESTIMATE, CIBERSORT and MCPcounter algorithms. IC50 of chemotherapeutic drugs was calculated by “pRRophetic” R package.

Results

TICAM1 was downregulated in WT patients with worse prognosis and a more advanced clinical stage. Moreover, a low expression level of TICAM1 contributed to less immune cell infiltration, few protective immune cells and more antitumor immune cells.

Conclusions

TICAM1 exerts a significant impact on the prognosis, progression and immune infiltration condition of WT.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01326-5.

Molecular characterization and expression analysis of TRIF, TRAF6, and TBK1 of golden pompano (Trachinotus ovatus)

Toll/IL-1R domain-containing adaptor-inducing IFN-β (TRIF), tumor necrosis factor receptor-associated factor 6 (TRAF6) and TANK-binding kinase 1 (TBK1) are critical signal transducers in toll-like receptors (TLRs) signaling pathway. In the present study, TRIF, TRAF6 and TBK1 were characterized from golden pompano (Trachinotus ovatus), named as TroTRIF, TroTRAF6 and TroTBK1, respectively. The full cDNA length of TroTRIF, TroTRAF6 and TroTBK1 was 2297 bp, 2293 bp, and 2482 bp, which respectively encoded 589, 573 and 723 amino acids. The deduced amino acids sequences of TroTRIF, TroTRAF6 and TroTBK1 contained conserved motifs, similar to their counterparts in other vertebrates. Phylogenetic tree analysis revealed that TroTRIF, TroTRAF6 and TroTBK1 were well clustered with their counterparts in other fish species. Quantitative Real-Time PCR (qPCR) analysis showed that TroTRIF, TroTBK1 and TroTRAF6 were detected in all examined tissues of healthy fish, but shared distinct transcript levels. Moreover, the expressions of TroTRIF, TroTBK1 and TroTRAF6 were generally induced by polyriboinosinic-polyribocytidylic acid (polyI:C), lipopolysaccharide (LPS), and Vibrio alginolyticus stimulation in vivo, indicating their critical roles in the immune defense of golden pompano against pathogen invasion. Our results provide valuable information for understanding the functions of these genes in golden pompano.

ADAR1 averts fatal type I interferon induction by ZBP1

Mutations of the ADAR1 gene encoding an RNA deaminase cause severe diseases associated with chronic activation of type I interferon (IFN) responses, including Aicardi–Goutières syndrome and bilateral striatal necrosis^1–3. The IFN-inducible p150 isoform of ADAR1 contains a Zα domain that recognizes RNA with an alternative left-handed double-helix structure, termed Z-RNA^4,5. Hemizygous ADAR1 mutations in the Zα domain cause type I IFN-mediated pathologies in humans^2,3 and mice^6–8; however, it remains unclear how the interaction of ADAR1 with Z-RNA prevents IFN activation. Here we show that Z-DNA-binding protein 1 (ZBP1), the only other protein in mammals known to harbour Zα domains⁹, promotes type I IFN activation and fatal pathology in mice with impaired ADAR1 function. ZBP1 deficiency or mutation of its Zα domains reduced the expression of IFN-stimulated genes and largely prevented early postnatal lethality in mice with hemizygous expression of ADAR1 with mutated Zα domain (Adar1^mZα/– mice). Adar1^mZα/– mice showed upregulation and impaired editing of endogenous retroelement-derived complementary RNA reads, which represent a likely source of Z-RNAs activating ZBP1. Notably, ZBP1 promoted IFN activation and severe pathology in Adar1^mZα/– mice in a manner independent of RIPK1, RIPK3, MLKL-mediated necroptosis and caspase-8-dependent apoptosis, suggesting a novel mechanism of action. Thus, ADAR1 prevents endogenous Z-RNA-dependent activation of pathogenic type I IFN responses by ZBP1, suggesting that ZBP1 could contribute to type I interferonopathies caused by ADAR1 mutations.

ADAR1 prevents Z-RNA-dependent activation of pathogenic type I interferon responses by ZBP1, whose activity may contribute to pathology in type I interferonopathies with ADAR1 mutations.

Toll-Like Receptor 3 in Cardiovascular Diseases

Toll-like receptor 3 (TLR3) is an important member of the innate immune response receptor toll-like receptors (TLRs) family, which plays a vital role in regulating immune response, promoting the maturation and differentiation of immune cells, and participating in the response of pro-inflammatory factors. TLR3 is activated by pathogen-associated molecular patterns and damage-associated molecular patterns, which support the pathophysiology of many diseases related to inflammation. An increasing number of studies have confirmed that TLR3, as a crucial medium of innate immunity, participates in the occurrence and development of cardiovascular diseases (CVDs) by regulating the transcription and translation of various cytokines, thus affecting the structure and physiological function of resident cells in the cardiovascular system, including vascular endothelial cells, vascular smooth muscle cells, cardiomyocytes, fibroblasts and macrophages. The dysfunction and structural damage of vascular endothelial cells and proliferation of vascular smooth muscle cells are the key factors in the occurrence of vascular diseases such as pulmonary arterial hypertension, atherosclerosis, myocardial hypertrophy, myocardial infarction, ischaemia/reperfusion injury, and heart failure. Meanwhile, cardiomyocytes, fibroblasts, and macrophages are involved in the development of CVDs. Therefore, the purpose of this review was to explore the latest research published on TLR3 in CVDs and discuss current understanding of potential mechanisms by which TLR3 contributes to CVDs. Even though TLR3 is a developing area, it has strong treatment potential as an immunomodulator and deserves further study for clinical translation.

Molecular Signaling Pathway Targeted Therapeutic Potential of Thymoquinone in Alzheimer’s disease

Alzheimer’s disease (AD) is a neurodegenerative disease with rapid progression. Black cumin (Nigella sativa) is a nutraceutical that has been investigated as a prophylactic and therapeutic agent for this disease due to its ability to prevent or retard the progression of neurodegeneration. Thymoquinone (TQ) is the main bioactive compound isolated from the seeds of black cumin. Several reports have shown that it has promising potential in the prevention and treatment of AD due to its significant antioxidative, anti-inflammatory, and antiapoptotic properties along with several other mechanisms that target the altered signaling pathways due to the disease pathogenesis. In addition, it shows anticholinesterase activity and prevents α-synuclein induced synaptic damage. The aim of this review is to summarize the potential aspects and mechanisms by which TQ imparts its action in AD.

Z-RNA and the Flipside of the SARS Nsp13 Helicase: Is There a Role for Flipons in Coronavirus-Induced Pathology?

We present evidence suggesting that the severe acute respiratory syndrome (SARS) coronavirus non-structural protein 13 (Nsp13) modulates the Z-RNA dependent regulated cell death pathways . We show that Z-prone sequences [called flipons] exist in coronavirus and provide a signature (Z-sig) that enables identification of the animal viruses from which the human pathogens arose. We also identify a potential RIP Homology Interaction Motif (RHIM) in the helicase Nsp13 that resembles those present in proteins that initiate Z-RNA-dependent cell death through interactions with the Z-RNA sensor protein ZBP1. These two observations allow us to suggest a model in which Nsp13 down regulates Z-RNA activated innate immunity by two distinct mechanisms. The first involves a novel ATP-independent Z-flipon helicase (flipase) activity in Nsp13 that differs from that of canonical A-RNA helicases. This flipase prevents formation of Z-RNAs that would otherwise activate cell death pathways. The second mechanism likely inhibits the interactions between ZBP1 and the Receptor Interacting Proteins Kinases RIPK1 and RIPK3 by targeting their RHIM domains. Together the described Nsp13 RHIM and flipase activities have the potential to alter the host response to coronaviruses and impact the design of drugs targeting the Nsp13 protein. The Z-sig and RHIM domains may provide a way of identifying previously uncharacterized viruses that are potentially pathogenic for humans.