TLR signaling pathways

The cerebroprotection and prospects of FNDC5/irisin in stroke

Stroke, the leading cause of disability and cognitive impairment, is also the second leading cause of death worldwide. The drugs with multi-targeted brain cytoprotective effects are increasingly being advocated for the treatment of stroke. Irisin, a newly discovered myokine produced by cleavage of fibronectin type III domain 5, has been shown to regulate glucose metabolism, mitochondrial energy, and fat browning. A large amount of evidence indicated that irisin could exert anti-inflammatory, anti-apoptotic, and antioxidant properties in a variety of diseases such as myocardial infarction, inflammatory bowel disease, lung injury, and kidney or liver disease. Studies have found that irisin is widely distributed in multiple brain regions and also plays an important regulatory role in the central nervous system. The most common cause of a stroke is a sudden blockage of an artery (ischemic stroke), and in some circumstances, a blood vessel rupture can also result in a stroke (hemorrhagic stroke). After a stroke, complicated pathophysiological processes lead to serious brain injury and neurological dysfunction. According to recent investigations, irisin may protect elements of the neurovascular unit by acting on multiple pathological processes in stroke. This review aims to outline the currently recognized effects of irisin on stroke and propose possible directions for future research.

Mass cytometry revealed the circulating immune cell landscape across different Suzuki stages of Moyamoya disease

Moyamoya disease (MMD) is a cerebrovascular disorder marked by progressive arterial narrowing, categorized into six stages known as Suzuki stages based on angiographic features. Growing evidence indicates a pivotal role of systemic immune and inflammatory responses in the initiation and advancement of MMD. This study employs high-dimensional mass cytometry to reveal the immunophenotypic characteristics of peripheral blood immune cells (PBMCs) at various Suzuki stages, offering insights into the progression of MMD. PBMC samples from eight patients with early-stage MMD (Suzuki stages II and III) and eight patients with later-stage MMD (Suzuki stages IV, V, and VI) were analyzed using high-dimensional mass cytometry to evaluate the frequency and phenotype of immune cell subtypes. We identified 15 cell clusters and found that the immunological features of early-stage MMD and later-stage MMD are composed of cluster variations. In this study, we confirmed that, compared to later-stage MMD, the early-stage MMD group exhibits an increase in non-classical monocytes. As the Suzuki stage level increases, the proportions of plasmacytoid DCs and monocyte-derived DCs decrease. Furthermore, T cells, monocytes, DCs, and PMN-MDSCs in the early-stage MMD group show activation of the canonical NF-κB signaling pathway. We summarized and compared the similarities and differences between early-stage MMD patients and later-stage MMD patients. There is a potential role of circulating immune dysfunction and inflammatory responses in the onset and development of MMD.

TLR7 in channel catfish (Ictalurus punctatus) is expressed in the endolysosome and is stimulated by synthetic ssRNA analogs, imiquimod, and resiquimod

Toll-like receptors (TLRs) are pivotal pattern recognition receptors (PRRs) and key mediators of innate immunity. Despite the significance of channel catfish (Ictalurus punctatus) in comparative immunology and aquaculture, its 20 TLR genes remain largely functionally uncharacterized. In this study, our aim was to determine the catfish TLR7 agonists, signaling potential, and cellular localization. Using a mammalian reporter system, we identified imiquimod and resiquimod, typical ssRNA analogs, as potent catfish TLR7 agonists. Notably, unlike grass carp TLR7, catfish TLR7 lacks the ability to respond to poly (I:C). Confocal microscopy revealed predominant catfish TLR7 expression in lysosomes, co-localizing with the endosomal chaperone protein, UNC93B1. Furthermore, imiquimod stimulation elicited robust IFNb transcription in peripheral blood leukocytes isolated from adult catfish. These findings underscore the conservation of TLR7 signaling in catfish, reminiscent of mammalian TLR7 responses. Our study sheds light on the functional aspects of catfish TLR7 and contributes to a better understanding of its role in immune defense mechanisms.

The AHR repressor limits expression of antimicrobial genes but not AHR-dependent genes in intestinal eosinophils

Intestinal eosinophils express the aryl hydrocarbon receptor (AHR), an environmental sensor and ligand-activated transcription factor that responds to dietary or environmental ligands. AHR regulates tissue adaptation, survival, adhesion, and immune functions in intestinal eosinophils. The AHR repressor (AHRR) is itself induced by AHR and believed to limit AHR activity in a negative feedback loop. We analyzed gene expression in intestinal eosinophils from wild-type and AHRR knockout mice and found that AHRR did not suppress most AHR-dependent genes. Instead, AHRR limited the expression of a distinct small set of genes involved in the innate immune response. These included S100 proteins, antimicrobial proteins, and alpha-defensins. Using bone marrow-derived eosinophils, we found that AHRR knockout eosinophils released more reactive oxygen species upon stimulation. This work shows that the paradigm of AHRR as a repressor of AHR transcriptional activity does not apply to intestinal eosinophils. Rather, AHRR limits the expression of innate immune response and antimicrobial genes, possibly to maintain an anti-inflammatory phenotype in eosinophils when exposed to microbial signals in the intestinal environment.

Bacillus siamensis Targeted Screening from Highly Colitis-Resistant Pigs Can Alleviate Ulcerative Colitis in Mice

Ulcerative colitis (UC) is often accompanied by intestinal inflammation and disruption of intestinal epithelial structures, which are closely associated with changes in the intestinal microbiota. We previously revealed that Min pigs, a native Chinese breed, are more resistant to dextran sulfate sodium (DSS)-induced colitis than commercial Yorkshire pigs. Characterizing the microbiota in Min pigs would allow identification of the core microbes that confer colitis resistance. By analyzing the microbiota linked to the disease course in Min and Yorkshire pigs, we observed that Bacillus spp. were enriched in Min pigs and positively correlated with pathogen resistance. Using targeted screening, we identified and validated Bacillus siamensis MZ16 from Min pigs as a bacterial species with biofilm formation ability, superior salt and pH tolerance, and antimicrobial characteristics. Subsequently, we administered B. siamensis MZ16 to conventional or microbiota-deficient BALB/c mice with DSS-induced colitis to assess its efficacy in alleviating colitis. B. siamensis MZ16 partially counteracted DSS-induced colitis in conventional mice, but it did not mitigate DSS-induced colitis in microbiota-deficient mice. Further analysis revealed that B. siamensis MZ16 administration improved intestinal ecology and integrity and immunological barrier function in mice. Compared to the DSS-treated mice, mice preadministered B. siamensis MZ16 exhibited improved relative abundance of potentially beneficial microbes (Lactobacillus, Bacillus, Christensenellaceae R7, Ruminococcus, Clostridium, and Eubacterium), reduced relative abundance of pathogenic microbes (Escherichia-Shigella), and maintained colonic OCLN and ZO-1 levels and IgA and SIgA levels. Furthermore, B. siamensis MZ16 reduced proinflammatory cytokine levels by reversing NF-κB and MAPK pathway activation in the DSS group. Overall, B. siamensis MZ16 from Min pigs had beneficial effects on a colitis mouse model by enhancing intestinal barrier functions and reducing inflammation in a gut microbiota-dependent manner.

TLR Agonists Modify NK Cell Activation and Increase Its Cytotoxicity in Acute Lymphoblastic Leukemia

Natural killer (NK) cells play a crucial role in innate immunity, particularly in combating infections and tumors. However, in hematological cancers, NK cells often exhibit impaired functions. Therefore, it is very important to activate its endosomal Toll-like receptors (TLRs) as a potential strategy to restore its antitumor activity. We stimulated NK cells from the peripheral blood mononuclear cells from children with acute lymphoblastic leukemia and NK cells isolated, and the NK cells were stimulated with specific TLR ligands (Poly I:C, Imiquimod, R848, and ODN2006) and we evaluated changes in IFN-γ, CD107a, NKG2D, NKp44 expression, Granzyme B secretion, cytokine/chemokine release, and cytotoxic activity. Results revealed that Poly I:C and Imiquimod enhanced the activation of both immunoregulatory and cytotoxic NK cells, increasing IFN-γ, CD107a, NKG2D, and NKp44 expression. R848 activated immunoregulatory NK cells, while ODN2006 boosted CD107a, NKp44, NKG2D, and IFN-γ secretion in cytotoxic NK cells. R848 also increased the secretion of seven cytokines/chemokines. Importantly, R848 and ODN 2006 significantly improved cytotoxicity against leukemic cells. Overall, TLR stimulation enhances NK cell activation, suggesting TLR8 (R848) and TLR9 (ODN 2006) ligands as promising candidates for antitumor immunotherapy.

TBK1 pharmacological inhibition mitigates osteoarthritis through attenuating inflammation and cellular senescence in chondrocytes

Objectives

TANK-binding kinase 1 (TBK1) is pivotal in autoimmune and inflammatory diseases, yet its role in osteoarthritis (OA) remains elusive. This study sought to elucidate the effect of the TBK1 inhibitor BX795 on OA and to delineate the underlying mechanism by which it mitigates OA.

Methods

Interleukin-1 Beta (IL-1β) was utilized to simulate inflammatory responses and extracellular matrix degradation in vitro. In vivo, OA was induced in 8-week-old mice through destabilization of the medial meniscus surgery. The impact of BX795 on OA was evaluated using histological analysis, X-ray, micro-CT, and the von Frey test. Additionally, Western blot, RT-qPCR, and immunofluorescence assays were conducted to investigate the underlying mechanisms of BX795.

Results

Phosphorylated TBK1 (P-TBK1) levels were found to be elevated in OA knee cartilage of both human and mice. Furthermore, intra-articular injection of BX795 ameliorated cartilage degeneration and alleviated OA-associated pain. BX795 also counteracted the suppression of anabolic processes and the augmentation of catabolic activity, inflammation, and senescence observed in the OA mice. In vitro studies revealed that BX795 reduced P-TBK1 levels and reversed the effects of anabolism inhibition, catabolism promotion, and senescence induction triggered by IL-1β. Mechanistically, BX795 inhibited the IL-1β-induced activation of the cGAS-STING and TLR3-TRIF signaling pathways in chondrocytes.

Conclusions

Pharmacological inhibition of TBK1 with BX795 protects articular cartilage by inhibiting the activation of the cGAS-STING and TLR3-TRIF signaling pathways. This action attenuates inflammatory responses and cellular senescence, positioning BX795 as a promising therapeutic candidate for OA treatment.

The translational potential of this article

This study furnishes experimental evidence and offers a potential mechanistic explanation supporting the efficacy of BX795 as a promising candidate for OA treatment.

Neuroprotective effect of taxifolin against aluminum chloride-induced dementia and pathological alterations in the brain of rats: possible involvement of toll-like receptor 4

Aluminum (Al) overexposure damages various organ systems, especially the nervous system. Regularly administered aluminum chloride (AlCl3) to rats causes dementia and pathophysiological alterations linked to Alzheimer's disease (AD). Taxifolin's neuroprotective effects against AlCl3-induced neurotoxicity in vitro and in vivo studies were studied. Taxifolin (0.1, 0.3, 1, 3, and 10 μM) was tested against AlCl3 (5 mM)-induced neurotoxicity in C6 and SH-SY5Y cells using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and lactate dehydrogenase (LDH) assays. Additionally, neural morphology was examined by confocal microscopy. Additionally, taxifolin's mode of binding with the co-receptor of toll-like receptor 4 (TLR4), human myeloid differentiation-2 (hMD-2) was investigated. AlCl3 (25 mg/kg/d, i.p.) was administered to rats for 14 d, and from the eighth day, taxifolin (1, 2, and 5 mg/kg/d, i.p.) was given along with AlCl3. This study assessed memory impairment using the Morris water maze, plus maze, and pole tests. This study also performed measurement of oxidant (malondialdehyde [MDA] and nitrite), antioxidant (reduced glutathione), and inflammatory (myeloperoxidase [MPO] activity, TLR4 expression) parameters in rats' brain in addition to histopathology. The docking score for taxifolin with hMD-2 was found to be -4.38 kcal/mol. Taxifolin treatment reduced the neurotoxicity brought on by AlCl3 in both C6 and SH-SY5Y cells. Treatment with 10 μM taxifolin restored AlCl3-induced altered cell morphology. AlCl3 administration caused memory loss, oxidative stress, inflammation (increased MPO activity and TLR4 expression), and brain atrophy. Taxifolin treatment significantly improved the AlCl3-induced memory impairment. Taxifolin treatment also mitigated the histopathological and neurochemical consequences of repeated AlCl3 administration in rats. Thus, taxifolin may protect the brain against AD.

CircSOD2: Disruption of intestinal mucosal barrier function in ulcerative colitis by regulating the miR-378g/Snail1 axis

BACKGROUND AND AIM

Circular RNA (circRNA) has been found to mediate ulcerative colitis (UC) progression by regulating intestinal mucosal barrier function. However, the role of circSOD2 in UC process and its underlying molecular mechanism still need to be further elucidated.

METHODS

Lipopolysaccharide (LPS)-induced Caco2 cells were used to mimic UC cell models. CircSOD2, miR-378g, and Snail1 levels were determined by quantitative real-time PCR. Cell viability was detected using MTT assay, and inflammatory cytokine levels were measured using ELISA. The intestinal mucosal barrier function was evaluated by testing transepithelial electrical resistance and fluorescein isothiocyanate (FITC)-dextran permeability. Snail1 and tight junction-related markers (Zo-1 and Claudin2) protein levels were examined using western blot. The interaction between miR-378g and circSOD2 or Snail1 was confirmed by dual-luciferase reporter assay. Dextran sulfate sodium (DSS) was used to induce UC rat models in vivo.

RESULTS

CircSOD2 was overexpressed in UC patients, and its knockdown significantly increased cell viability, transepithelial electrical resistance, and tight junction-related protein expression, while reduced inflammation cytokine levels and the permeability of FITC-dextran in LPS-induced Caco2 cells. In terms of mechanism, circSOD2 sponged miR-378g to positively regulate Snail1 expression. MiR-378g inhibitor reversed the effect of circSOD2 knockdown on intestinal mucosal barrier injury and Snail1 expression in LPS-induced Caco2 cells. In DSS-induced UC rat models, circSOD2 knockdown also could repair the intestinal mucosal barrier injury through regulating miR-378g/Snail1 axis.

CONCLUSION

CircSOD2 could destroy intestinal mucosal barrier function in LPS-induced Caco2 cells and DSS-induced UC rats by miR-378g/Snail1 axis.

Unlocking the power of Zc3h12c: Orchestrating Macrophage activation and elevating the innate immune response

The activation of macrophages, essential for the innate defense against invading pathogens, revolves around Toll-like receptors (TLRs). Nevertheless, a comprehensive understanding of the molecular mechanisms governing TLR signaling in the course of macrophage activation remains to be fully clarified. Although Zc3h12c was originally identified as being enriched in organs associated with macrophages, its precise function remains elusive. In this study, we observed a significant induction of Zc3h12c in macrophages following stimulation with TLR agonists and pathogens. Overexpression of Zc3h12c significantly mitigated the release of TNF-α and IL-6 triggered by lipopolysaccharide (LPS), whereas depletion of Zc3h12c increased the production of the cytokines mentioned above. Notably, the expression of IFN-β was not influenced by Zc3h12c. Luciferase reporter assays revealed that Zc3h12c could suppress the TNF-α promoter activity. Moreover, Zc3h12c exerted a notable inhibitory effect on JNK, ERK, p38, and NF-κB signaling induced by LPS. In summary, the findings of our study suggest that Zc3h12c functions as a robust suppressor of innate immunity, potentially playing a role in the pathogenesis of infectious diseases.

Mitochondrial Reactive Oxygen Species in Infection and Immunity

Reactive oxygen species (ROS) contain at least one oxygen atom and one or more unpaired electrons and include singlet oxygen, superoxide anion radical, hydroxyl radical, hydroperoxyl radical, and free nitrogen radicals. Intracellular ROS can be formed as a consequence of several factors, including ultra-violet (UV) radiation, electron leakage during aerobic respiration, inflammatory responses mediated by macrophages, and other external stimuli or stress. The enhanced production of ROS is termed oxidative stress and this leads to cellular damage, such as protein carbonylation, lipid peroxidation, deoxyribonucleic acid (DNA) damage, and base modifications. This damage may manifest in various pathological states, including ageing, cancer, neurological diseases, and metabolic disorders like diabetes. On the other hand, the optimum levels of ROS have been implicated in the regulation of many important physiological processes. For example, the ROS generated in the mitochondria (mitochondrial ROS or mt-ROS), as a byproduct of the electron transport chain (ETC), participate in a plethora of physiological functions, which include ageing, cell growth, cell proliferation, and immune response and regulation. In this current review, we will focus on the mechanisms by which mt-ROS regulate different pathways of host immune responses in the context of infection by bacteria, protozoan parasites, viruses, and fungi. We will also discuss how these pathogens, in turn, modulate mt-ROS to evade host immunity. We will conclude by briefly giving an overview of the potential therapeutic approaches involving mt-ROS in infectious diseases.

Identification of toll-like receptor family and the immune function of new Sptlr-6 gene of Scylla paramamosain

As a crucial member of pattern-recognition receptors (PRRs), the Tolls/Toll-like receptors (TLRs) gene family has been proven to be involved in innate immunity in crustaceans. In this study, nine members of TLR gene family were identified from the mud crab (Scylla paramamosain) transcriptome, and the structure and phylogeny of different SpTLRs were analyzed. It was found that different SpTLRs possessed three conserved structures in the TIR domain. Meanwhile, the expression patterns of different Sptlr genes in examined tissues detected by qRT-PCR had wide differences. Compared with other Sptlr genes, Sptlr-6 gene was significantly highly expressed in the hepatopancreas and less expressed in other tissues. Therefore, the function of Sptlr-6 was further investigated. The expression of the Sptlr-6 gene was up-regulated by Poly I: C, PGN stimulation and Vibrio parahaemolyticus infection. In addition, the silencing of Sptlr-6 in hepatopancreas mediated by RNAi technology resulted in the significant decrease of several conserved genes involved in innate immunity in mud crab after V. parahaemolyticus infection, including relish, myd88, dorsal, anti-lipopolysaccharide factor (ALF), anti-lipopolysaccharide factor 2 (ALF-2) and glycine-rich antimicrobial peptide (glyamp). This study provided new knowledge for the role of the Sptlr-6 gene in defense against V. parahaemolyticus infection in S. paramamosain.

Suppression of MyD88 disturbs gut microbiota and activates the NLR pathway and hence fails to ameliorate DSS-induced colitis

Background

Myeloid differentiation factor 88 (MyD88) is the core adaptor for Toll-like receptors defending against microbial invasion and initiating a downstream immune response during microbiota-host interaction. However, the role of MyD88 in the pathogenesis of inflammatory bowel disease is controversial. This study aims to investigate the impact of MyD88 on intestinal inflammation and the underlying mechanism.

Methods

MyD88 knockout (MyD88-/-) mice and the MyD88 inhibitor (TJ-M2010-5) were used to investigate the impact of MyD88 on acute dextran sodium sulfate (DSS)-induced colitis. Disease activity index, colon length, histological score, and inflammatory cytokines were examined to evaluate the severity of colitis. RNA transcriptome analysis and 16S rDNA sequencing were used to detect the potential mechanism.

Results

In an acute DSS-colitis model, the severity of colitis was not alleviated in MyD88-/- mice and TJ-M2010-5-treated mice, despite significantly lower levels of NF-κB activation being exhibited compared to control mice. Meanwhile, 16S rDNA sequencing and RNA transcriptome analysis revealed a higher abundance of intestinal Proteobacteria and an up-regulation of the nucleotide oligomerization domain-like receptors (NLRs) signaling pathway in colitis mice following MyD88 suppression. Further blockade of the NLRs signaling pathway or elimination of gut microbiota with broad-spectrum antibiotics in DSS-induced colitis mice treated with TJ-M2010-5 ameliorated the disease severity, which was not improved solely by MyD88 inhibition. After treatment with broad-spectrum antibiotics, downregulation of the NLR signaling pathway was observed.

Conclusion

Our study suggests that the suppression of MyD88 might be associated with unfavorable changes in the composition of gut microbiota, leading to NLR-mediated immune activation and intestinal inflammation.

An overview on the cellular mechanisms of anthocyanins in maintaining intestinal integrity and function

Structural and functional changes of the intestinal barrier, as a consequence of a number of (epi)genetic and environmental causes, have a main role in penetrations of pathogens and toxic agents, and lead to the development of inflammation-related pathological conditions, not only at the level of the GI tract but also in other extra-digestive tissues and organs. Anthocyanins (ACNs), a subclass of polyphenols belonging to the flavonoid group, are well known for their health-promoting properties and are widely distributed in the human diet. There is large evidence about the correlation between the human intake of ACN-rich products and a reduction of intestinal inflammation and dysfunction. Our review describes the more recent advances in the knowledge of cellular and molecular mechanisms through which ACNs can modulate the main mechanisms involved in intestinal dysfunction and inflammation, in particular the inhibition of the NF-κB, JNK, MAPK, STAT3, and TLR4 proinflammatory pathways, the upregulation of the Nrf2 transcription factor and the expression of tight junction proteins and mucins.

TLR2 Mediates Microglial Activation and Contributes to Central Sensitization in a Recurrent Nitroglycerin-induced Chronic Migraine Model

Central sensitization is an important pathophysiological mechanism underlying chronic migraine (CM). Previous studies have shown that microglial activation and subsequent inflammation in the trigeminal nucleus caudalis (TNC) contribute to central sensitization. Toll-like receptor 2 (TLR2) is a receptor expressed on the membrane of microglia and participates in central sensitization in inflammatory and chronic pain; however, its role in CM is unclear. Therefore, this study investigated TLR2 involvement in CM in detail. Mice treated with recurrent nitroglycerin (NTG) were used as a CM model. Hyperalgesia was assessed using a 50% paw mechanical threshold and a 50% periorbital threshold on a Von Frey filament pain meter. Western blotting and immunofluorescence analyses were used to detect the expression of TLR2, microglia, c-fos and CGRP in TNC. The expression of inflammatory factors (IL-6, IL-1β、 IL-10、TNF-α and IFN-β1) was detected using quantitative real-time polymerase chain reaction (qRT-PCR). A selective TLR2 antagonist (C29) was systematically administered to observe its effect on hyperalgesia, microglia activation and the expression of c-fos, CGRP and inflammatory factors. Recurrent administration of NTG resulted in acute and chronic hypersensitivity, accompanied by upregulation of TLR2 expression and microglial activation in TNC. C29 partially inhibited pain hypersensitivity. C29 suppressed microglial activation induced by NTG administration. Inhibition of TLR2 reduced the expression of c-fos and CGRP in TNC after NTG treatment. C29 inhibited the expression of inflammatory mediators in TNC. These data showed that microglial TLR2 plays a critical role in the pathogenesis of CM by regulating microglial activation in TNC.

Relationship of Toll-Like Receptor 7, 9, and 10 Polymorphisms and the Severity of Coronavirus Disease 2019

Coronavirus disease 2019 (COVID-19) is a pandemic that is still affecting people and has caused many deaths. Toll-like receptors (TLRs) have an important role in the binding of disease agents to the host cell, disease susceptibility and severity, and host disease resistance. In this study, we investigated the frequencies of TLR7 (C.4-151 A/G), TLR9 (T-1486C and G2848A), and TLR10 (720A/C and 992T/A) single nucleotide polymorphisms in 150 cases with COVID-19 and 171 control samples. We also examined whether TLR7, TLR9, and TLR10 were related to COVID-19 severity. Furthermore, we analyzed the association between COVID-19 and some clinical parameters. Polymerase chain reaction based on restriction fragment length polymorphisms performed for the TLR7, TLR9, and TLR10 single nucleotide polymorphisms. TLR7 C.4-151 A/G G allele and GG genotype; TLR9 T-1486C C allele and TC, CC genotypes; and TLR10 720A/C C allele; TLR10 992T/A A allele and AA genotype frequencies were statistically significant in cases with COVID-19 compared with controls (P < 0.05*). In addition, there was a statistically significant difference in the distribution of TLR7, TLR9, and TLR10 allele and genotype frequencies between the severity groups (P < 0.05*). Our findings suggest that TLR7, TLR9, and TLR10 polymorphisms may be crucial for the clinical course and susceptibility to infection.

Cigarette smoke sustains immunosuppressive microenvironment inducing M2 macrophage polarization and viability in lung cancer settings

BACKGROUND

It is amply demonstrated that cigarette smoke (CS) has a high impact on lung tumor progression worsening lung cancer patient prognosis and response to therapies. Alteration of immune cell types and functions in smokers' lungs have been strictly related with smoke detrimental effects. However, the role of CS in dictating an inflammatory or immunosuppressive lung microenvironment still needs to be elucidated. Here, we investigated the effect of in vitro exposure to cigarette smoke extract (CSE) focusing on macrophages.

METHODS

Immortalized murine macrophages RAW 264.7 cells were cultured in the presence of CS extract and their polarization has been assessed by Real-time PCR and cytofluorimetric analysis, viability has been assessed by SRB assay and 3D-cultures and activation by exposure to Poly(I:C). Moreover, interaction with Lewis lung carcinoma (LLC1) murine cell models in the presence of CS extract were analyzed by confocal microscopy.

RESULTS

Obtained results indicate that CS induces macrophages polarization towards the M2 phenotype and M2-phenotype macrophages are resistant to the CS toxic activity. Moreover, CS impairs TLR3-mediated M2-M1 phenotype shift thus contributing to the M2 enrichment in lung smokers.

CONCLUSIONS

These findings indicate that, in lung cancer microenvironment of smokers, CS can contribute to the M2-phenotype macrophages prevalence by different mechanisms, ultimately, driving an anti-inflammatory, likely immunosuppressive, microenvironment in lung cancer smokers.

Sex-related immunity: could Toll-like receptors be the answer in acute inflammatory response?

An increasing number of studies have highlighted the existence of a sex-specific immune response, wherein men experience a worse prognosis in cases of acute inflammatory diseases. Initially, this sex-dependent inflammatory response was attributed to the influence of sex hormones. However, a growing body of evidence has shifted the focus toward the influence of chromosomes rather than sex hormones in shaping these inflammatory sex disparities. Notably, certain pattern recognition receptors, such as Toll-like receptors (TLRs), and their associated immune pathways have been implicated in driving the sex-specific immune response. These receptors are encoded by genes located on the X chromosome. TLRs are pivotal components of the innate immune system, playing crucial roles in responding to infectious diseases, including bacterial and viral pathogens, as well as trauma-related conditions. Importantly, the TLR-mediated inflammatory responses, as indicated by the production of specific proteins and cytokines, exhibit discernible sex-dependent patterns. In this review, we delve into the subject of sex bias in TLR activation and explore its clinical implications relatively to both the X chromosome and the hormonal environment. The overarching objective is to enhance our understanding of the fundamental mechanisms underlying these sex differences.

The HPV viral regulatory mechanism of TLRs and the related treatments for HPV-associated cancers

Infection with human papillomavirus (HPV) typically leads to cervical cancer, skin related cancers and many other tumors. HPV is mainly responsible for evading immune tumor monitoring in HPV related cancers. Toll like receptors (TLRs) are particular pattern recognition molecules. When the body is facing immune danger, it can lead to innate and direct adaptive immunity. TLR plays an important role in initiating antiviral immune responses. HPV can affect the expression level of TLR and interfere with TLR related signaling pathways, resulting in sustained viral infection and even carcinogenesis. This paper introduces the HPV virus and HPV related cancers. We discussed the present comprehension of TLR, its expression and signaling, as well as its role in HPV infection. We also provided a detailed introduction to immunotherapy methods for HPV related diseases based on TLR agonists. This will provide insights into methods that support the therapeutic method of HPV related conditions with TLR agonists.

Lysosome-related genes predict acute myeloid leukemia prognosis and response to immunotherapy

Background

Acute myeloid leukemia (AML) is a highly aggressive and pathogenic hematologic malignancy with consistently high mortality. Lysosomes are organelles involved in cell growth and metabolism that fuse to form specialized Auer rods in AML, and their role in AML has not been elucidated. This study aimed to identify AML subtypes centered on lysosome-related genes and to construct a prognostic model to guide individualized treatment of AML.

Methods

Gene expression data and clinical data from AML patients were downloaded from two high-throughput sequencing platforms. The 191 lysosomal signature genes were obtained from the database MsigDB. Lysosomal clusters were identified by unsupervised consensus clustering. The differences in molecular expression, biological processes, and the immune microenvironment among lysosomal clusters were subsequently analyzed. Based on the molecular expression differences between lysosomal clusters, lysosomal-related genes affecting AML prognosis were screened by univariate cox regression and multivariate cox regression analyses. Algorithms for LASSO regression analyses were employed to construct prognostic models. The risk factor distribution, KM survival curve, was applied to evaluate the survival distribution of the model. Time-dependent ROC curves, nomograms and calibration curves were used to evaluate the predictive performance of the prognostic models. TIDE scores and drug sensitivity analyses were used to explore the implication of the model for AML treatment.

Results

Our study identified two lysosomal clusters, cluster1 has longer survival time and stronger immune infiltration compared to cluster2. The differences in biological processes between the two lysosomal clusters are mainly manifested in the lysosomes, vesicles, immune cell function, and apoptosis. The prognostic model consisting of six prognosis-related genes was constructed. The prognostic model showed good predictive performance in all three data sets. Patients in the low-risk group survived significantly longer than those in the high-risk group and had higher immune infiltration and stronger response to immunotherapy. Patients in the high-risk group showed greater sensitivity to cytarabine, imatinib, and bortezomib, but lower sensitivity to ATRA compared to low -risk patients.

Conclusion

Our prognostic model based on lysosome-related genes can effectively predict the prognosis of AML patients and provide reference evidence for individualized immunotherapy and pharmacological chemotherapy for AML.

MyD88 and Its Inhibitors in Cancer: Prospects and Challenges

The interplay between the immune system and cancer underscores the central role of immunotherapy in cancer treatment. In this context, the innate immune system plays a critical role in preventing tumor invasion. Myeloid differentiation factor 88 (MyD88) is crucial for innate immunity, and activation of MyD88 promotes the production of inflammatory cytokines and induces infiltration, polarization, and immune escape of immune cells in the tumor microenvironment. Additionally, abnormal MyD88 signaling induces tumor cell proliferation and metastasis, which are closely associated with poor prognosis. Therefore, MyD88 could serve as a novel tumor biomarker and is a promising target for cancer therapy. Current strategies targeting MyD88 including inhibition of signaling pathways and protein multimerization, have made substantial progress, especially in inflammatory diseases and chronic inflammation-induced cancers. However, the specific role of MyD88 in regulating tumor immunity and tumorigenic mechanisms remains unclear. Therefore, this review describes the involvement of MyD88 in tumor immune escape and disease therapy. In addition, classical and non-classical MyD88 inhibitors were collated to provide insights into potential cancer treatment strategies. Despite several challenges and complexities, targeting MyD88 is a promising avenue for improving cancer treatment and has the potential to revolutionize patient outcomes.

Unraveling the Complexities of Toll-like Receptors: From Molecular Mechanisms to Clinical Applications

Toll-like receptors (TLRs) are vital components of the innate immune system, serving as the first line of defense against pathogens by recognizing a wide array of molecular patterns. This review summarizes the critical roles of TLRs in immune surveillance and disease pathogenesis, focusing on their structure, signaling pathways, and implications in various disorders. We discuss the molecular intricacies of TLRs, including their ligand specificity, signaling cascades, and the functional consequences of their activation. The involvement of TLRs in infectious diseases, autoimmunity, chronic inflammation, and cancer is explored, highlighting their potential as therapeutic targets. We also examine recent advancements in TLR research, such as the development of specific agonists and antagonists, and their application in immunotherapy and vaccine development. Furthermore, we address the challenges and controversies surrounding TLR research and outline future directions, including the integration of computational modeling and personalized medicine approaches. In conclusion, TLRs represent a promising frontier in medical research, with the potential to significantly impact the development of novel therapeutic strategies for a wide range of diseases.

Porphyromonas gingivalis lipopolysaccharide regulates cell proliferation, apoptosis, autophagy in esophageal squamous cell carcinoma via TLR4/MYD88/JNK pathway

The study aimed to explore the impact and potential mechanism of Porphyromonas gingivalis lipopolysaccharide (LPS-PG) on esophageal squamous cell carcinoma (ESCC) cell behavior. ESCC cells from the Shanghai Cell Bank were used, and TLR4, MYD88, and JNK interference vectors were constructed using adenovirus. The cells were divided into six groups: Control, Model, Model + radiotherapy + LPS-PG, Model + radiotherapy + 3-MA, Model + radiotherapy + LPS-PG + 3-MA, and Model + radiotherapy. Various radiation doses were applied to determine the optimal dose, and a radioresistant ESCC cell model was established and verified. CCK8 assay measured cell proliferation, flow cytometry and Hoechst 33258 assay assessed apoptosis, and acridine orange fluorescence staining tested autophagy. Western blot analyzed the expression of LC3II, ATG7, P62, and p-ULK1. Initially, CCK8 and acridine orange fluorescence staining identified optimal LPS-PG intervention conditions. Results revealed that 10 ng/ml LPS-PG for 12 h was optimal. LPS-PG increased autophagy activity, while 3-MA decreased it. LPS-PG + 3-MA group exhibited reduced autophagy. LPS-PG promoted proliferation and autophagy, inhibiting apoptosis in radioresistant ESCCs. LPS-PG regulated TLR4/MYD88/JNK pathway, enhancing ESCC autophagy, proliferation, and radioresistance. In conclusion, LPS-PG, through the TLR4/MYD88/JNK pathway, promotes ESCC proliferation, inhibits apoptosis, and enhances radioresistance by inducing autophagy.

CIRC_0003907 MODULATES SEPSIS-INDUCED MYOCARDIAL INJURY VIA ENHANCING MYD88/NLRP3/NF-ΚB AXIS BY SPONGING MIR-944

ABSTRACT

Background : Sepsis-induced cardiomyopathy ( SIC ) is a common complication of sepsis with high morbidity and mortality but lacks specific therapy. The purpose of this study was to investigate the role of circularRNA_0003907 (circ_0003907) in myocardium injury induced by sepsis. Methods: In this experiment, human AC16 cells were treated with lipopolysaccharide (LPS) to induce an in vitro cardiomyocyte injury model. Expression of circ_0003907, microRNA-944 (miR-944), and MYD88 was detected using quantitative real-time polymerase chain reaction. Cell proliferation and apoptosis were assessed using 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide, thymidine analog 5-ethynyl-2'-deoxyuridine, and flow cytometry assays. Secretions of proinflammatory cytokines IL-6 and TNF-α were detected using ELISA kits. Superoxide dismutase (SOD) activity and malondialdehyde (MDA) level were detected using special kits. Protein levels of cyclin D1, cleaved caspase-3, MYD88, NLRP3, P65, and IκBα were determined using western blot assay. After being predicted using Circineractome and starBase, the interaction between miR-944 and circ_0003907 or MYD88 was confirmed using dual-luciferase reporter and RNA immunoprecipitation assays. Results: Circ_0003907 expression was increased in serum from SIC patients and in LPS-treated AC16 cells. Circ_0003907 knockdown might abolish LPS-triggered proliferation inhibition, and the promotion of apoptosis, inflammatory response, and oxidative stress in AC16 cells. In mechanism, circ_0003907 acted as a sponge for miR-944 to increase MYD88 expression. Meanwhile, the absence of circ_0003907 induced miR-944 expression and suppressed MYD88/NLRP3/NF-κB levels. Conclusion: Circ_0003907 sponged miR-944 to aggravate LPS-induced AC16 cell dysfunction via activating the MYD88/NLRP3/NF-κB axis during sepsis, which might provide a new direction for the treatment of SIC .

RNA m5C methylation modification: a potential therapeutic target for SARS-CoV-2-associated myocarditis

The Corona Virus Disease (COVID-19), caused by the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), has quickly spread worldwide and resulted in significant morbidity and mortality. Although most infections are mild, some patients can also develop severe and fatal myocarditis. In eukaryotic RNAs, 5-methylcytosine (m5C) is a common kind of post-transcriptional modification, which is involved in regulating various biological processes (such as RNA export, translation, and stability maintenance). With the rapid development of m5C modification detection technology, studies related to viral m5C modification are ever-increasing. These studies have revealed that m5C modification plays an important role in various stages of viral replication, including transcription and translation. According to recent studies, m5C methylation modification can regulate SARS-CoV-2 infection by modulating innate immune signaling pathways. However, the specific role of m5C modification in SARS-CoV-2-induced myocarditis remains unclear. Therefore, this review aims to provide insights into the molecular mechanisms of m5C methylation in SARS-CoV-2 infection. Moreover, the regulatory role of NSUN2 in viral infection and host innate immune response was also highlighted. This review may provide new directions for developing therapeutic strategies for SARS-CoV-2-associated myocarditis.

miRNA-Mediated Fine Regulation of TLR-Induced M1 Polarization

Macrophage polarization to the M1 spectrum is induced by bacterial cell wall components through stimulation of Toll-like family (TLR) receptors. By orchestrating the expression of relevant mediators of the TLR cascade, as well as associated pathways and feedback loops, macrophage polarization is coordinated to ensure an appropriate immune response. This is central to the successful control of pathogens and the maintenance of health. Macrophage polarization is known to be modulated at both the transcriptional and post-transcriptional levels. In recent years, the miRNA-based post-transcriptional regulation of M1 polarization has received increasing attention from the scientific community. Comparative studies have shown that TLR stimulation alters the miRNA profile of macrophages and that macrophages from the M1 or the M2 spectrum differ in terms of miRNAs expressed. Simultaneously, miRNAs are considered critical post-transcriptional regulators of macrophage polarization. In particular, miRNAs are thought to play a regulatory role in the switch between the early proinflammatory response and the resolution phase. In this review, we will discuss the current state of knowledge on the complex interaction of transcriptional and post-transcriptional regulatory mechanisms that ultimately determine the functionality of macrophages.

Protein Expression of TLR2, TLR4, and TLR9 on Monocytes in TB, HIV, and TB/HIV

Toll-like receptors (TLRs) have a critical role in recognizing pathogenic patterns and initiating immune responses against TB and HIV. Previously, studies described the gene expression of TLRs in patients with TB and HIV. Here, we demonstrated TLRs protein expressions and their association with clinical status and plasma markers in TB, HIV, and TB/HIV coinfection. The phenotyping of TLR2, TLR4, and TLR9 on CD14+ monocytes and their subsets were determined by multicolor flow cytometry. Host plasma biomarkers and microbial indices were measured using Luminex Multiplex assay and standard of care tools, respectively. TLR2 expression significantly enhanced in TB, slightly increased in HIV but slightly reduced in TB/HIV coinfection compared to apparently health controls (HC). On the other hand, TLR4 expression was significantly increased in TB, HIV, and TB/HIV compared to HC. Expression of TLR4 was equally enhanced on classical and intermediate monocytes while higher TLR2 expression on intermediate than classical monocytes. TLR4 had a positive correlation pattern with plasma biomarkers while TLR2 had an inverse correlation pattern. TLR4 is associated with disease severity while TLR2 is with the immune-competent status of patients. Our findings demonstrated that the pattern of TLR expression is disease as well as monocyte subset specific and distinct factors drive these differences.

Truncating NFKB1 variants cause combined NLRP3 inflammasome activation and type I interferon signaling and predispose to necrotizing fasciitis

In monogenic autoinflammatory diseases, mutations in genes regulating innate immune responses often lead to uncontrolled activation of inflammasome pathways or the type I interferon (IFN-I) response. We describe a mechanism of autoinflammation potentially predisposing patients to life-threatening necrotizing soft tissue inflammation. Six unrelated families are identified in which affected members present with necrotizing fasciitis or severe soft tissue inflammations. Exome sequencing reveals truncating monoallelic loss-of-function variants of nuclear factor κ light-chain enhancer of activated B cells (NFKB1) in affected patients. In patients' macrophages and in NFKB1-variant-bearing THP-1 cells, activation increases both interleukin (IL)-1β secretion and IFN-I signaling. Truncation of NF-κB1 impairs autophagy, accompanied by the accumulation of reactive oxygen species and reduced degradation of inflammasome receptor nucleotide-binding oligomerization domain, leucine-rich repeat-containing protein 3 (NLRP3), and Toll/IL-1 receptor domain-containing adaptor protein inducing IFN-β (TRIF), thus leading to combined excessive inflammasome and IFN-I activity. Many of the patients respond to anti-inflammatory treatment, and targeting IL-1β and/or IFN-I signaling could represent a therapeutic approach for these patients.

Dietary Peppermint Extract Inhibits Chronic Heat Stress-Induced Activation of Innate Immunity and Inflammatory Response in the Spleen of Broiler Chickens

The aim of this study was to investigate the effect of dietary peppermint extract (PE) on innate immunity and inflammatory responses in the spleen of broiler chickens under chronic heat stress. In order to further study the mechanism of the activation of innate immunity and inflammation induced by chronic heat stress and the regulatory effect of peppermint extract, we examined the spleen's histological change, the mRNA expression of major pattern recognition receptors (PRRs) (TLR2, TLR4, NOD1, MDA5 and DAI) and transcription factors (NF-κB, AP-1 and IRF3) and downstream inflammatory cytokines (IFN-α, IFN-β, IL-1β, IL-6 and TNF-α) of innate immune signaling pathways associated with heat stress in the spleen of broiler chickens. The results indicated that chronic heat stress damaged the spleen tissue. In addition, chronic heat stress induced the activation of innate immunity and inflammatory responses by increasing the mRNA expression of TLR2, TLR4 and DAI, mRNA expression of transcriptional factors (NF-κB, AP-1 and IRF3) and the concentration of downstream inflammatory cytokines in the spleen of broiler chickens. Dietary peppermint extract alleviated the damage of spleen tissue caused by chronic heat stress. In addition, peppermint extract reduced the mRNA expression of DAI, mRNA expression of transcriptional factors NF-κB, AP-1 and IRF3, and the concentration of inflammatory cytokines in the spleen of broiler chickens under chronic heat stress. In conclusion, dietary peppermint extract could have a beneficial effect on regulating inflammatory response and innate immunity via inhibiting the activation of NF-κB, AP-1 and IRF3 signaling pathways mediated by DAI in the spleen of broiler chickens induced by chronic heat stress.

Study on anti-inflammatory effect of Shangkehuangshui in vitro and in vivo based on TLR4/TLR2-NF-κB signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Shangkehuangshui (SK) has been traditionally used to treat traumatic injury, soft tissue and bone injury in Foshan hospital of traditional Chinese medicine for more than 60 years, which composed of many Chinese herbs such as Coptis chinensis Franch., Gardenia jasminoides Ellis, Phellodendron chinense Schneid. and etc. SK exhibits heat-clearing and detoxifying, enhancing blood circulation to eliminate blood stasis properties, and demonstrates noteworthy clinical efficacy. Nevertheless, the underlying mechanism remains uncertain.

AIM OF THE STUDY

The early study found that SK had good anti-inflammatory effects in acute soft tissue injury model. This research is to verify the anti-inflammatory properties of SK both in vitro and in vivo via TLR4/TLR2-NF-κB signaling pathway, to clarify the underlying mechanisms responsible for the curative effect of SK.

METHODS

The RAW264.7 cells inflammatory model was established with lipopolysaccharide (LPS) in vitro. NO and TNF-α, IL-6, IL-1β were determined with Griess method and ELISA method respectively. The mRNA and protein expression levels of TLR4/TLR2-NF-κB pathway were evaluated by qPCR and Western blot method. In vivo experiment, chronic soft tissue injury rat models were established by tracking gastrocnemius muscle with electrical stimulation, then local appearance and pathological changes were observed and recorded, the contents of inflammatory factors in serum and tissue were performed. Moreover, we also measured and contrasted the expression of TLR4/TLR2-NF-κB related factors.

RESULTS

SK effectively inhibited the LPS-induced generation of inflammatory cytokines, including NO, TNF-α, IL-6 and IL-1β in RAW264.7 cells, and significantly suppressed the expression of TLR4, TLR2, MyD88, IκB, and NF-κB. In vivo, SK remarkably decreased the damage appearance scores after 4 and 14 days of administration and inhibit the quantity of NO and leukocytes present in the serum. Additionally, the inflammatory infiltration in the pathological section was alleviated, myofibrillar hyperplasia and blood stasis were reduced. SK markedly downregulated NO, TNF-α, IL-6 and IL-1β in injured tissues of rats, also declined the expression of TLR4, TLR2, MyD88, IκB, NF-κB, IL-6, TNF-α and IL-1β.

CONCLUSION

This study revealed that SK had obvious effects of anti-inflammatory actions in vivo and vitro, effectively reduced acute and chronic soft tissue injury in clinical, this might be attributed to inhibit the TLR4/TLR2-NF-κB pathway, further inhibit the expression of downstream relevant pro-inflammatory cytokines.

An Immunoinformatics-Based Study of Mycobacterium tuberculosis Region of Difference-2 Uncharacterized Protein (Rv1987) as a Potential Subunit Vaccine Candidate for Preliminary Ex Vivo Analysis

Mycobacterium tuberculosis (Mtb) is the pathogen that causes tuberculosis and develops resistance to many of the existing drugs. The sole licensed TB vaccine, BCG, is unable to provide a comprehensive defense. So, it is crucial to maintain the immunological response to eliminate tuberculosis. Our previous in silico study reported five uncharacterized proteins as potential vaccine antigens. In this article, we considered the uncharacterized Mtb H37Rv regions of difference (RD-2) Rv1987 protein as a promising vaccine candidate. The vaccine quality of the protein was analyzed using reverse vaccinology and immunoinformatics-based quality-checking parameters followed by an ex vivo preliminary investigation. In silico analysis of Rv1987 protein predicted it as surface localized, secretory, single helix, antigenic, non-allergenic, and non-homologous to the host protein. Immunoinformatics analysis of Rv1987 by CD4 + and CD8 + T-cells via MHC-I and MHC-II binding affinity and presence of B-cell epitope predicted its immunogenicity. The docked complex analysis of the 3D model structure of the protein with immune cell receptor TLR-4 revealed the protein's capability for potential interaction. Furthermore, the target protein-encoded gene Rv1987 was cloned, over-expressed, purified, and analyzed by mass spectrometry (MS) to report the target peptides. The qRT-PCR gene expression analysis shows that it is capable of activating macrophages and significantly increasing the production of a number of key cytokines (TNF-α, IL-1β, and IL-10). Our in-silico analysis and ex vivo preliminary investigations revealed the immunogenic potential of the target protein. These findings suggest that the Rv1987 be undertaken as a potent subunit vaccine antigen and that further animal model immuno-modulation studies would boost the novel TB vaccine discovery and/or BCG vaccine supplement pipeline.

Short chain fatty acids inhibit corneal inflammatory responses to TLR ligands via the ocular G-protein coupled receptor 43

PURPOSE

Short chain fatty acids (SCFAs) produced by gut microbiota are known to play primary roles in gut homeostasis by immunomodulation partially through G-protein coupled receptors (GPR) 43. Using mouse models of TLR ligand induced keratitis, we investigated whether SCFAs and GPR43 play any regulatory roles in the pathogenesis of inflammatory responses in the eye.

METHODS

Both human and mouse eyes were labeled with a specific antibody for GPR43 and imaged by a laser scanning confocal microscope. Corneal cups from naïve C57BL/6J (B6) and GPR43 knockout (KO) mice were stimulated with TLR ligands in the presence or absence of sodium butyrate overnight and then processed for RT-PCR assay for expression of GPR43 and cytokines. Keratitis was induced by Poly I:C in wild type (WT) B6, GPR43KO and chimeric mice and the disease severity was evaluated by the corneal fluorescein staining test, and infiltrating cell staining and calculating in corneal whole mount.

RESULTS

GPR43 is expressed in both human and mouse eyes and the expression is bidirectionally regulated by TLR ligands and butyrate. Butyrate significantly inhibited inflammation caused by several TLR ligands such as Poly I:C, Flagellin, and CpG-ODN (TLR-3, 5 and 9 agonists, respectively) in WT, but not GPR43KO, mice. Butyrate inhibition of TLR-induced keratitis is mediated by the GPR43 expressed in tissue but not hematopoietic, cells.

CONCLUSIONS

This is the first report to demonstrate of the protective effect of SCFAs on microbial keratitis, and the dynamic expression and anti-inflammatory function of GPR43 in the eye. SCFAs can modulate inflammation and immunity in the eye through GPR43.

A TNF-IL-1 circuit controls Yersinia within intestinal pyogranulomas

Tumor necrosis factor (TNF) is a pleiotropic inflammatory cytokine that mediates antimicrobial defense and granuloma formation in response to infection by numerous pathogens. We previously reported that Yersinia pseudotuberculosis colonizes the intestinal mucosa and induces the recruitment of neutrophils and inflammatory monocytes into organized immune structures termed pyogranulomas (PG) that control Yersinia infection. Inflammatory monocytes are essential for the control and clearance of Yersinia within intestinal PG, but how monocytes mediate Yersinia restriction is poorly understood. Here, we demonstrate that TNF signaling in monocytes is required for bacterial containment following enteric Yersinia infection. We further show that monocyte-intrinsic TNFR1 signaling drives the production of monocyte-derived interleukin-1 (IL-1), which signals through IL-1 receptors on non-hematopoietic cells to enable PG-mediated control of intestinal Yersinia infection. Altogether, our work reveals a monocyte-intrinsic TNF-IL-1 collaborative inflammatory circuit that restricts intestinal Yersinia infection.

Exploiting Leishmania-Primed Dendritic Cells as Potential Immunomodulators of Canine Immune Response

Dendritic cells (DCs) capture pathogens and process antigens, playing a crucial role in activating naïve T cells, bridging the gap between innate and acquired immunity. However, little is known about DC activation when facing Leishmania parasites. Thus, this study investigates in vitro activity of canine peripheral blood-derived DCs (moDCs) exposed to L. infantum and L. amazonensis parasites and their extracellular vesicles (EVs). L. infantum increased toll-like receptor 4 gene expression in synergy with nuclear factor κB activation and the generation of pro-inflammatory cytokines. This parasite also induced the expression of class II molecules of major histocompatibility complex (MHC) and upregulated co-stimulatory molecule CD86, which, together with the release of chemokine CXCL16, can attract and help in T lymphocyte activation. In contrast, L. amazonensis induced moDCs to generate a mix of pro- and anti-inflammatory cytokines, indicating that this parasite can establish a different immune relationship with DCs. EVs promoted moDCs to express class I MHC associated with the upregulation of co-stimulatory molecules and the release of CXCL16, suggesting that EVs can modulate moDCs to attract cytotoxic CD8+ T cells. Thus, these parasites and their EVs can shape DC activation. A detailed understanding of DC activation may open new avenues for the development of advanced leishmaniasis control strategies.

Involvement of tumor necrosis factor receptor-associated factor 6 (TRAF6) in NF-κB activation and antiviral immunity: Molecular and functional characterization of TRAF6 in red-spotted grouper (Epinephelus akaara)

Tumor necrosis factor receptor-associated factor 6 (TRAF6) is a member of the TRAF family of adaptor proteins involved in the signal transduction pathways of both TNF receptor and interleukin-1 receptor/Toll-like receptor superfamilies. In this study, red-spotted grouper (Epinephelus akaara) TRAF6 (EaTraf6) was identified and characterized. The open reading frame of EaTraf6, 1713 bp in length, encodes a putative protein of 570 amino acids and has a predicted molecular weight and theoretical isoelectric point of 64.11 kDa and 6.07, respectively. EaTraf6 protein contains an N-terminal RING-type zinc finger domain, two TRAF-type zinc finger domains, a coiled-coil region (zf-TRAF), and a conserved C-terminal meprin and TRAF homology (MATH) domain. EaTraf6 shared the highest amino acid sequence identity with its ortholog from Epinephelus coioides, and phylogenetic analysis showed all fish TRAF6s clustered together and apart from other species. qRT-PCR results revealed that EaTraf6 was ubiquitously expressed in all examined tissues, with the highest level detected in the blood. In the immune challenge, EaTraf6 exhibited modulated mRNA expression levels in the blood and spleen. The subcellular localization analysis revealed that the EaTraf6 protein was predominantly present in the cytoplasm; however, it could translocate into the nucleus following poly (I:C) stimulation. The antiviral function of EaTraf6 was confirmed by analyzing the expression of host antiviral genes and viral genomic RNA during viral hemorrhagic septicemia virus infection. Additionally, luciferase reporter assay results indicated that EaTraf6 is involved in the activation of the NF-κB signaling pathway upon poly (I:C) stimulation. Finally, the effect of EaTraf6 on cytokine gene expression and its role in regulating macrophage M1 polarization were demonstrated. Collectively, these findings suggest that EaTraf6 is a crucial immune-related gene that significantly contributes to antiviral functions and regulation of NF-κB activity in the red-spotted grouper.

Schaftoside reduces inflammation in Aspergillus fumigatus keratitis through the inhibition of the TLR4/MyD88 pathway

PURPOSE

The purpose of this research study was to investigate the impact of schaftoside on Aspergillus fumigatus (A. fumigatus) keratitis and elucidate its underlying mechanisms.

METHODS

In order to establish safe experimental concentrations of schaftoside in human corneal epithelial cells (HCECs), RAW264.7 cells, and mouse models, various techniques were employed including cytotoxicity assay (CCK-8) assay, cell scratch assay, and Draize test. The therapeutic effect of schaftoside was assessed using slit-lamp biomicroscopy, clinical scores, as well as determination of neutrophil infiltration through hematoxylin and eosin (HE) staining, immunofluorescence (IF) staining, and myeloperoxidase (MPO) assay. The levels of Toll-like receptor 4 (TLR4), myeloid differentiation primary response 88 (MyD88), pro-inflammatory mediators interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and IL-6 were determined using quantitative real-time polymerase chain reaction (qRT-PCR), western blotting, and IF techniques.

RESULTS

Schaftoside at a concentration of 160 μM displayed no harmful side effects on HCECs, RAW cells, and mouse corneas, rendering it suitable for further experiments. In a murine fungal keratitis model, schaftoside mitigated the severity of fungal keratitis by inhibiting neutrophil infiltration and reducing MPO activity. Both in vitro and in vivo experiments demonstrated that schaftoside treatment suppressed the upregulation of IL-1β, TNF-α, and IL-6 expression, while also downregulating the expressions of TLR4 as well as MyD88 at both mRNA and protein levels.

CONCLUSIONS

Schaftoside demonstrated a protective effect against A. fumigatus keratitis by reducing corneal damage through inhibition of neutrophil recruitment and downstream inflammatory cytokines. The anti-inflammatory properties of schaftoside in A. fumigatus keratitis may involve modulation of the TLR4/MyD88 pathway.

Tick salivary protein Cystatin: structure, anti-inflammation and molecular mechanism

Ticks are blood-sucking ectoparasites that secrete immunomodulatory substances in saliva to hosts during engorging. Cystatins, a tick salivary protein and natural inhibitor of Cathepsins, are attracting growing interest globally because of the immunosuppressive activities and the feasibility as an antigen for developing anti-tick vaccines. This review outlines the classification and the structure of tick Cystatins, and focuses on the anti-inflammatory effects and molecular mechanisms. Tick Cystatins can be divided into four families based on structures and cystatin 1 and cystatin 2 are the most abundant. They are injected into hosts during blood feeding and effectively mitigate the host inflammatory response. Mechanically, tick Cystatins exert anti-inflammatory properties through the inhibition of TLR-NF-κb, JAK-STAT and p38 MAPK signaling pathways. Further investigations are crucial to confirm the reduction of inflammation in other cell types like neutrophils and mast cells, and fully elucidate the underlying mechanism (like the structural mechanism) to make Cystatin a potential candidate for the development of novel anti-inflammation agents.

Adaptor molecules mediate negative regulation of macrophage inflammatory pathways: a closer look

Macrophages play a central role in initiating, maintaining, and terminating inflammation. For that, macrophages respond to various external stimuli in changing environments through signaling pathways that are tightly regulated and interconnected. This process involves, among others, autoregulatory loops that activate and deactivate macrophages through various cytokines, stimulants, and other chemical mediators. Adaptor proteins play an indispensable role in facilitating various inflammatory signals. These proteins are dynamic and flexible modulators of immune cell signaling and act as molecular bridges between cell surface receptors and intracellular effector molecules. They are involved in regulating physiological inflammation and also contribute significantly to the development of chronic inflammatory processes. This is at least partly due to their involvement in the activation and deactivation of macrophages, leading to changes in the macrophages' activation/phenotype. This review provides a comprehensive overview of the 20 adaptor molecules and proteins that act as negative regulators of inflammation in macrophages and effectively suppress inflammatory signaling pathways. We emphasize the functional role of adaptors in signal transduction in macrophages and their influence on the phenotypic transition of macrophages from pro-inflammatory M1-like states to anti-inflammatory M2-like phenotypes. This endeavor mainly aims at highlighting and orchestrating the intricate dynamics of adaptor molecules by elucidating the associated key roles along with respective domains and opening avenues for therapeutic and investigative purposes in clinical practice.

Exploring the Function of (+)-Naltrexone Precursors: Their Activity as TLR4 Antagonists and Potential in Treating Morphine Addiction

Disruptions in the toll-like receptor 4 (TLR4) signaling pathway are linked to chronic inflammation, neuropathic pain, and drug addiction. (+)-Naltrexone, an opioid-derived TLR4 antagonist with a (+)-isomer configuration, does not interact with classical opioid receptors and has moderate blood-brain barrier permeability. Herein, we developed a concise 10-step synthesis for (+)-naltrexone and explored its precursors, (+)-14-hydroxycodeinone (1) and (+)-14-hydroxymorphinone (3). These precursors exhibited TLR4 antagonistic activities 100 times stronger than (+)-naltrexone, particularly inhibiting the TLR4-TRIF pathway. In vivo studies showed that these precursors effectively reduced behavioral effects of morphine, like sensitization and conditioned place preference by suppressing microglial activation and TNF-α expression in the medial prefrontal cortex and ventral tegmental area. Additionally, 3 displayed a longer half-life and higher oral bioavailability than 1. Overall, this research optimized (+)-naltrexone synthesis and identified its precursors as potent TLR4 antagonists, offering potential treatments for morphine addiction.

Irisin: An unveiled bridge between physical exercise and a healthy brain

AIMS

Physical exercise has been widely recognized for its positive effects on health and well-being. Recently, the impact of exercise on the nervous system has gained attention, with evidence indicating improvements in attention, memory, neurogenesis, and the release of "happiness hormones." One potential mediator of these benefits is Irisin, a myokine induced by exercise that can cross the blood-brain barrier, reduce neuroinflammation, and counteract neurodegeneration. The objective of this study is to conduct a systematic review of animal trials to summarize the neuroprotective effects of Irisin injection in mitigating neuroinflammation and neurodegeneration.

MATERIALS AND METHODS

Two independent reviewers screened three databases (PubMed, Embase, and Google Scholar) in November 2022. Animal studies assessing the neuroprotective effects of Irisin in mitigating neuroinflammation or counteracting neurodegeneration were included. The methodological quality of the included studies was assessed using SYRCLE's Risk of Bias tool.

KEY FINDINGS

Twelve studies met the inclusion criteria. Irisin injection in rodents significantly reduced neuroinflammation, cytokine cascades, and neurodegeneration. It also protected neurons from damage and apoptosis, reduced oxidative stress, blood-brain barrier disruption, and neurobehavioral deficits following disease or injury. Various mechanisms were suggested to be responsible for these neuroprotective effects. Most of the included studies presented a low risk of bias based on SYRCLE's Risk of Bias tool. Irisin injection demonstrated the potential to alleviate neuroinflammation and counteract neurodegeneration in rodent models through multiple pathways. However, further research is needed to fully understand its mechanism of action and its potential applications in clinical practice and drug discovery.

Role of toll-like receptor 4 in skeletal muscle damage in chronic limb-threatening ischemia

Objective

Toll-like receptors (TLRs) are key pattern recognition receptors in the innate immune system. In particular, the TLR4-mediated immune response has been implicated in ischemia-induced tissue injury. Mounting evidence supports a detrimental role of the innate immune system in the pathophysiology of skeletal muscle damage in patients with chronic limb-threatening ischemia (CLTI), in whom patient-oriented functional outcomes are poor. The overall aim of this study was to investigate the potential role of TLR4 in skeletal muscle dysfunction and damage in CLTI.

Methods

The role of TLR4 in ischemic muscle was investigated by (1) studying TLR4 expression and distribution in human gastrocnemius muscle biopsies, (2) evaluating the functional consequences of TLR4 inhibition in myotubes derived from human muscle biopsies, and (3) assessing the therapeutic potential of modulating TLR4 signaling in ischemic muscle in a mouse hindlimb ischemia model.

Results

TLR4 was found to be expressed in human muscle biopsies, with significant upregulation in samples from patients with CLTI. In vitro studies using cultured human myotubes demonstrated upregulation of TLR4 in ischemia, with activation of the downstream signaling pathway. Inhibition of TLR4 before ischemia was associated with reduced ischemia-induced apoptosis. Upregulation of TLR4 also occurred in ischemia in vivo and TLR4 inhibition was associated with decreased inflammatory cell infiltration and diminished apoptosis in the ischemic limb.

Conclusions

TLR4 is upregulated and activated in ischemic skeletal muscle in patients with CLTI. Modulating TLR4 signaling in vitro and in vivo was associated with attenuation of ischemia-induced skeletal muscle damage. This strategy could be explored further for potential clinical application.

An integrated transcriptomics and network pharmacology approach to explore the mechanism of Wang-Bi tablet against SAPHO syndrome

BACKGROUND

SAPHO syndrome is recognized as a rare entity with damage to skin and bones due to inflammation. Currently, the treatment for SAPHO syndrome is still a challenge in clinical practice. In this study, an integrated transcriptomics and network pharmacology approach was applied to explore the therapeutic effect and mechanism of Wang-Bi tablet (WBT) on SAPHO syndrome.

METHODS

The main components of WBT and their targets, as well as the targets of SAPHO syndrome, were collected from databases. Network visualization was performed using Cytoscape software. The GO and KEGG enrichment analysis was executed by David dataset. Then, the molecular mechanism of WBT improving SAPHO syndrome was validated by transcriptomics of peripheral blood neutrophils in SAPHO syndrome. Finally, the above results were validated by molecular docking.

RESULTS

The Network Pharmacology results showed there are 152 core targets for WBT treatment on SAPHO syndrome. RNA-seq data showed 442 differentially expressed genes (DEGs) in peripheral blood neutrophils of SAPHO patients. Intriguingly, NIK/NF-kappaB-, MyD88-dependent toll-like receptor-, and MAPK pathway were included in the enrichment results of network pharmacology and RNA-seq. Moreover, we verified that the core components of WBT have good affinity with the core targets of NIK/NF-kappaB-, MyD88-dependent toll-like receptor-, and MAPK pathway by molecular docking.

CONCLUSIONS

This study illustrated that the possible mechanisms of WBT against SAPHO syndrome may be related to NIK/NF-kappaB-, MyD88-dependent toll-like receptor-, and MAPK pathway, and further experiments are needed to prove these predictions.

Potential promising anticancer applications of β-glucans: a review

β-Glucans are valuable functional polysaccharides distributed in nature, especially in the cell walls of fungi, yeasts, bacteria, and cereals. The unique features of β-glucans, such as water solubility, viscosity, molecular weight, and so on, have rendered them to be broadly applied in various food systems as well as in medicine to improve human health. Moreover, inhibition of cancer development could be achieved by an increase in immune system activity via β-glucans. β-glucans, which are part of a class of naturally occurring substances known as biological response modifiers (BRMs), have also shown evidence of being anti-tumorogenic, anti-cytotoxic, and anti-mutagenic. These properties make them attractive candidates for use as pharmaceutical health promoters. Along these lines, they could activate particular proteins or receptors, like lactosylceramide (LacCer), Dickin-1, complement receptor 3 (CR3), scavenge receptors (SR), and the toll-like receptor (TLR). This would cause the release of cytokines, which would then activate other antitumor immune cells, like macrophages stimulating neutrophils and monocytes. These cells are biased toward pro-inflammatory cytokine synthesis and phagocytosis enhancing the elicited immunological responses. So, to consider the importance of β-glucans, the present review introduces the structure characteristics, biological activity, and antitumor functions of fungal β-glucans, as well as their application.

Role of APOE in glaucoma

Glaucoma is a chronic blinding eye disease caused by the progressive loss of retinal ganglion cells (RGCs). Currently, no clinically approved treatment can directly improve the survival rate of RGCs. The Apolipoprotein E (APOE) gene is closely related to the genetic risk of numerous neurodegenerative diseases and has become a hot topic in the field of neurodegenerative disease research in recent years. The optic nerve and retina are extensions of the brain's nervous system. The pathogenesis of retinal degenerative diseases is closely related to the degenerative diseases of the nerves in the brain. APOE consists of three alleles, ε4, ε3, and ε2, in a single locus. They have varying degrees of risk for glaucoma. APOE4 and the APOE gene deletion (APOE-/-) can reduce RGC loss. By contrast, APOE3 and the overall presence of APOE genes (APOE+/+) result in significant loss of RGC bodies and axons, increasing the risk of glaucoma RGCs death. Currently, there is no clear literature indicating that APOE2 is beneficial or harmful to glaucoma. This study summarises the mechanism of different APOE genes in glaucoma and speculates that APOE targeted intervention may be a promising method for protecting against RGCs loss in glaucoma.

Possible involvement of DExD/H box helicase 60 in synovial inflammation of rheumatoid arthritis: role of toll-like receptor 3 signaling

BACKGROUND

Innate immunity is known to be implicated in the etiology of synovitis in rheumatoid arthritis (RA). However, details of the molecular mechanisms have not been fully clarified. DExD/H-box helicase 60 (DDX60), a putative RNA helicase, is of consequence in anti-viral innate immune reactions followed by inflammation. Although DDX60 is involved in the pathogenesis of autoimmune diseases such as systemic lupus nephritis, the role of DDX60 in RA has not been elucidated. The objective of this study was to examine the expression and the role of DDX60 in RA synovial inflammation.

METHODS AND RESULTS

DDX60 protein expression was investigated by immunohistochemistry in synovial tissues resected from 4 RA and 4 osteoarthritis (OA) patients. We found that synovial DDX60 expression was more intense in RA than in OA. Treatment of human rheumatoid fibroblast-like synoviocytes in culture with polyinosinic-polycytidylic acid, a Toll-like receptor 3 (TLR3) ligand, increased DDX60 protein and mRNA expression. A knockdown experiment of DDX60 using RNA interference revealed a decrease in the expression of poly IC-induced C-X-C motif chemokine ligand 10 (CXCL10) which induces lymphocyte chemotaxis.

CONCLUSIONS

The synovial DDX60 was more expressed in RA patients than in OA. In human RFLS, DDX60 stimulated by TLR3 signaling affected CXCL10 expression. DDX60 may contribute to synovial inflammation in RA.

Advances in crosstalk among innate immune pathways activated by mitochondrial DNA

Mitochondria are not only the power plant for intracellular oxidative phosphorylation and ATP synthesis, but also involved in cell proliferation, differentiation, signaling and apoptosis. Recent studies have shown that mitochondria play an important role in other pathophysiological functions in addition to cellular energy metabolism. Mitochondria release mitochondrial DNA (mtDNA) as a damage-associated molecular pattern (DAMP) to activate Toll-like receptor 9 (TLR9), NOD-, LRR-, and pyrin domain-containing 3 (NLRP3) inflammasome and cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) innate immune signaling pathways against foreign pathogenic microorganisms. The innate immune response not only promotes antimicrobial immune defense and regulates antiviral signaling, but their overactivation also induces the onset and progression of inflammatory diseases. In this paper, we review the role of mtDNA in the activation of innate immune signaling pathways and the crosstalk among innate immune signaling pathways activated by mtDNA, providing clues for the study of inflammatory diseases caused by mtDNA cytoplasmic translocation.

Study on the mechanism of action of Wu Mei Pill in inhibiting rheumatoid arthritis through TLR4-NF-κB pathway

BACKGROUND

Wu Mei Pills (WMP) is a traditional Chinese medication that exhibits considerable anti-inflammatory effects. While WMP has been documented for its efficacy in treating RA, its mechanism of action on the condition remains unestablished.

METHODS

The chemical composition of WMP was analyzed through UPLC-MS. Next, the enzyme-linked immunosorbent assay, cell scratch, Transwell, and Western blotting techniques were used to investigate its intrinsic mechanism. Lastly, the effect of WMP in inhibiting RA was explored by applying it to CIA rats.

RESULT

UPLC-MS analysis detected 181 compounds in WMP. RA-FLS migration and invasion mechanisms were significantly hindered by serum containing WMP (2%, 8%). Moreover, WMP (0.5 g/kg, 2 g/kg) restricted arthritis and immune organ indices in CIA rats with type II collagen-induced rheumatoid arthritis by blocking TLR4-NF-κB inflammatory pathway activation.

CONCLUSIONS

WMP is valuable in mitigating the course of RA through inhibiting the classical TLR4-NF-κB inflammatory pathway and reducing the secretion of inflammatory factors in the serum of RA-FLS and CIA rats. Moreover, it regulates the dynamic balance of MMP-2/TIMP-2, MMP-9/TIMP-1, modulates the mechanism of RA-FLS invasion, and safeguards articular cartilage tissues in RA.

Deciphering the role of neddylation in tumor microenvironment modulation: common outcome of multiple signaling pathways

Neddylation is a post-translational modification process, similar to ubiquitination, that controls several biological processes. Notably, it is often aberrantly activated in neoplasms and plays a critical role in the intricate dynamics of the tumor microenvironment (TME). This regulatory influence of neddylation permeates extensively and profoundly within the TME, affecting the behavior of tumor cells, immune cells, angiogenesis, and the extracellular matrix. Usually, neddylation promotes tumor progression towards increased malignancy. In this review, we highlight the latest understanding of the intricate molecular mechanisms that target neddylation to modulate the TME by affecting various signaling pathways. There is emerging evidence that the targeted disruption of the neddylation modification process, specifically the inhibition of cullin-RING ligases (CRLs) functionality, presents a promising avenue for targeted therapy. MLN4924, a small-molecule inhibitor of the neddylation pathway, precisely targets the neural precursor cell-expressed developmentally downregulated protein 8 activating enzyme (NAE). In recent years, significant advancements have been made in the field of neddylation modification therapy, particularly the integration of MLN4924 with chemotherapy or targeted therapy. This combined approach has demonstrated notable success in the treatment of a variety of hematological and solid tumors. Here, we investigated the inhibitory effects of MLN4924 on neddylation and summarized the current therapeutic outcomes of MLN4924 against various tumors. In conclusion, this review provides a comprehensive, up-to-date, and thorough overview of neddylation modifications, and offers insight into the critical importance of this cellular process in tumorigenesis.

Immunometabolism in the pathogenesis of asthma

Bronchial asthma is a heterogeneous disease characterised by chronic airway inflammation. A variety of immune cells such as eosinophils, mast cells, T lymphocytes, neutrophils and airway epithelial cells are involved in the airway inflammation and airway hyperresponsiveness in asthma pathogenesis, resulting in extensive and variable reversible expiratory airflow limitation. However, the precise molecular mechanisms underlying the allergic immune responses, particularly immunometabolism, remains unclear. Studies have detected enhanced oxidative stress, and abnormal metabolic progresses of glycolysis, fatty acid and amino acid in various immune cells, inducing dysregulation of innate and adaptive immune responses in asthma pathogenesis. Immunometabolism mechanisms contain multiple signalling pathways, providing novel therapy targets for asthma. This review summarises the current knowledge on immunometabolism reprogramming in asthma pathogenesis, as well as potential therapy strategies.

Phytocannabinoids as Potential Multitargeting Neuroprotectants in Alzheimer's Disease

The Endocannabinoid System (ECS) is a well-studied system that influences a variety of physiological activities. It is evident that the ECS plays a significant role in metabolic activities and also has some neuroprotective properties. In this review, we emphasize several plant-derived cannabinoids such as β-caryophyllene (BCP), Cannabichromene (CBC), Cannabigerol (CBG), Cannabidiol (CBD), and Cannabinol (CBN), which are known to have distinctive modulation abilities of ECS. In Alzheimer's disease (AD), the activation of ECS may provide neuroprotection by modulating certain neuronal circuitry pathways through complex molecular cascades. The present article also discusses the implications of cannabinoid receptors (CB1 and CB2) as well as cannabinoid enzymes (FAAH and MAGL) modulators in AD. Specifically, CBR1 or CB2R modulations result in reduced inflammatory cytokines such as IL-2 and IL-6, as well as a reduction in microglial activation, which contribute to an inflammatory response in neurons. Furthermore, naturally occurring cannabinoid metabolic enzymes (FAAH and MAGL) inhibit the NLRP3 inflammasome complex, which may offer significant neuroprotection. In this review, we explored the multi-targeted neuroprotective properties of phytocannabinoids and their possible modulations, which could offer significant benefits in limiting AD.