Targeting Toll like Receptors in Cancer: Role of TLR Natural and Synthetic Modulators

TLR4 inhibitors through inhibiting (MYD88-TRIF) pathway, protect against experimentally-induced intestinal (I/R) injury

Intestinal ischemia/reperfusion (I/R) injury is a serious condition that causes intestinal dysfunction and can be fatal. Previous research has shown that toll-like receptor 4 (TLR4) inhibitors have a protective effect against this injury. This study aimed to investigate the protective effects of TLR4 inhibitors, specifically cyclobenzaprine, ketotifen, amitriptyline, and naltrexone, in rats with intestinal (I/R) injury. Albino rats were divided into seven groups: vehicle control, sham-operated, I/R injury, I/R-cyclobenzaprine (10 mg/kg body weight), I/R-ketotifen (1 mg/kg body weight), I/R-amitriptyline (10 mg/kg body weight), and I/R-naltrexone (4 mg/kg body weight) groups. Anesthetized rats (urethane 1.8 g/kg) underwent 30 min of intestinal ischemia by occluding the superior mesenteric artery (SMA), followed by 2 h of reperfusion. Intestinal tissue samples were collected to measure various parameters, including malondialdehyde (MDA), nitric oxide synthase (NO), myeloperoxidase (MPO), superoxide dismutase (SOD), TLR4, intercellular adhesion molecule-1 (ICAM-1), nuclear factor kappa bp65 (NF-ĸBP65), monocyte chemoattractant protein-1 (MCP-1), tumor necrosis factor-α (TNF-α), macrophages CD68, myeloid differentiation factor 88 (MYD88), and toll interleukin receptor-domain-containing adaptor-inducing interferon β (TRIF). The use of TLR4 inhibitors significantly reduced MDA, MPO, and NO levels, while increasing SOD activity. Furthermore, it significantly decreased TLR4, ICAM-1, TNF-α, MCP-1, MYD88, and TRIF levels. These drugs also showed partial restoration of normal cellular structure with reduced inflammation. Additionally, there was a decrease in NF-ĸBP65 and macrophages CD68 staining compared to rats in the I/R groups. This study focuses on how TLR4 inhibitors enhance intestinal function and protect against intestinal (I/R) injury by influencing macrophages CD86 through (MYD88-TRIF) pathway, as well as their effects on oxidation and inflammation.

Rho kinase inhibitor Y-27632 downregulates IL-1β expression in mice with experimental autoimmune myocarditis

Autoimmune myocarditis is the limited or diffuse inflammation of the myocardium due to dysfunctional cellular and humoral immunity mechanisms. We constructed mouse models of experimental autoimmune myocarditis (EAM) using peptide MyHC-α614-629. On the day after secondary immunization, the mice were intraperitoneally injected with Rho kinase (ROCK) inhibitor Y-27632. On day 21, the cardiac tissues were harvested and weighed. The hearts of EAM mice were significantly enlarged and whitened. Furthermore, body weight (BW) slowly increased during the treatment period, the heart weight (HW) and the ratio of HW/eventual BW were increased, and inflammatory infiltration and fibrosis were aggravated in the myocardial tissue. Y-27632 treatment improved the aforementioned phenotypic and pathological features of EAM mice. Mechanistic analysis revealed a significant increase in Notch1, Hes1, Jag2, Dil1, Toll-like receptor (Tlr) 2, and interleukin (IL)-1β expression in the myocardial tissue of EAM mice. Notably, IL-1β expression was correlated with that of Notch1 and Tlr2. Following Y-27632 treatment, the expression of key target genes of the Notch signaling pathway (Notch1, Hes1, Dil1, and Jag2) and Tlr2 were obviously decreased. Y-27632 treatment also decreased the number of monocytes in the spleen of EAM mice. Thus, ROCK inhibitor Y-27632 exerted a protective effect in EAM mice by downregulating IL-1β expression. This study aimed to provide a reference point for the future treatment of myocarditis in clinical settings.

Network pharmacology based research into the effect and potential mechanism of Portulaca oleracea L. polysaccharide against ulcerative colitis

BACKGROUND

Ulcerative colitis (UC) as a chronic inflammatory bowel disease (IBD) has received extensive concerns worldwide. As a traditional herbal medicine, Portulaca oleracea L. (POL) has a wide application in gastrointestinal diseases such as diarrhea and dysentery. This study aims to investigate the target and potential mechanisms of Portulaca oleracea L. polysaccharide (POL-P) in the treatment of UC.

METHOD

The active ingredients and relevant targets of POL-P were searched through the TCMSP and Swiss Target Prediction databases. UC related targets were collected through the GeneCards and DisGeNET databases. The intersection of POL-P targets with UC targets was done using Venny. Then, protein-protein interaction (PPI) network of the intersection targets was constructed through the STRING database and analyzed using Cytohubba to identify the key targets of POL-P in the treatment of UC. In addition, GO and KEGG enrichment analyses were performed on the key targets and the binding mode of POL-P to the key targets was further analyzed by molecular docking technology. Finally, the efficacy and target of POL-P were verified using animal experiments and immunohistochemical staining.

RESULTS

A total of 316 targets were obtained based on POL-P monosaccharide structures, among which 28 were related to UC. Cytohubba analysis showed that VEGFA, EGFR, TLR4, IL-1β, STAT3, IL-2, PTGS2, FGF2, HGF, and MMP9 were the key targets for UC treatment and were mainly involved in multiple signaling pathways such as proliferation, inflammation, and immune response. Molecular docking results revealed that POL-P had a good binding potential to TLR4. In vivo validation results showed that POL-P significantly reduced the overexpression of TLR4 and its downstream key proteins (MyD88 and NF-κB) in intestinal mucosa of UC mice, which indicated that POL-P improved UC by mediating TLR4 related proteins.

CONCLUSION

POL-P may be a potential therapeutic agent for UC and its mechanism is closely related to the regulation of TLR4 protein. This study will provide novel insights for the treatment of UC with POL-P.

CpG DNA-triggered upregulation of TLR9 expression affects apoptosis and immune responses in human plasmacytoid dendritic cells isolated from chronic hepatitis B patients

Plasmacytoid dendritic cells (pDCs) were treated with cytosine-phosphate-guanine (CpG) DNA, and cell apoptosis, signals and immune responses were measured to investigate the effects and mechanism of CpG DNA in pDCs from chronic hepatitis B patients. CpG DNA-stimulated pDCs secreted more IFN-α than the control pDCs. CpG DNA activated Toll-like receptor 9 (TLR9), thereby resulting in the upregulated expression of myeloid differentiation primary response gene 88 (MyD88), interferon regulatory factor 7 (IRF7) and nuclear factor kappa B (NF-κB). Furthermore, CpG DNA down-regulated apoptosis and promoted the expression of IFN-α, interleukin-12 (IL-12), IL-21, IL-26 and tumour necrosis factor-α (TNF-α) in pDCs. Following treatment with NF-κB inhibitor, pyrollidine dithiocarbamate (PDTC), the influence of CpG DNA on pDCs was inhibited. Our results suggest that CpG DNA may directly interfere with the function of pDCs through TLR9-mediated upregulation of MyD88, IRF7 and NF-κB expression, which can partially explain the activation of pDCs in chronic hepatitis B patients.

Recombinant Domain of Flagellin Promotes In Vitro a Chemotactic Inflammatory Profile in Human Immune Cells Independently of a Dendritic Cell Phenotype

Flagellin is the major component of the flagellum in gram-positive and -negative bacteria and is also the ligand for the Toll-like receptor 5 (TLR5). The activation of TLR5 promotes the expression of proinflammatory cytokines and chemokines and the subsequent activation of T cells. This study evaluated a recombinant domain from the amino-terminus D1 domain (rND1) of flagellin from Vibrio anguillarum, a fish pathogen, as an immunomodulator in human peripheral blood mononuclear cells (PBMCs) and monocyte-derived dendritic cells (MoDCs). We demonstrated that rND1 induced an upregulation of proinflammatory cytokines in PBMCs, characterized at the transcriptional level by an expression peak of 220-fold for IL-1β, 20-fold for IL-8, and 65-fold for TNF-α. In addition, at the protein level, 29 cytokines and chemokines were evaluated in the supernatant and were correlated with a chemotactic signature. MoDCs treated with rND1 showed low levels of co-stimulatory and HLA-DR molecules and kept an immature phenotype with a decreased phagocytosis of dextran. We probed that rND1 from a non-human pathogen promotes modulation in human cells, and it may be considered for further studies in adjuvant therapies based on pathogen-associated patterns (PAMPs).

Polymorphisms in toll-like receptor 3 and 4 genes as prognostic and outcome biomarkers in melanoma patients

Melanoma is one of the most aggressive tumors, and in the setting of rising incidence and mortality, there is an urgent need to identify new prognostic markers. Toll-like receptors (TLRs), are aberrantly expressed in numerous cancers, including melanoma. TLR signaling provides a microenvironment that is involved in antitumor immune response, chronic inflammation, cancer cell proliferation and evasion of immune destruction. In the present study, we investigated whether single nucleotide polymorphisms (SNPs) in TLR3 and TLR4 genes are associated with clinicopathologic features, progression and survival of melanoma patients. The study was conducted on 120 melanoma patients. DNA extracted from peripheral blood was genotyped for TLR3 polymorphisms rs5743312 and rs3775291 (L412F) and TLR4 polymorphisms rs4986790 (D299G) and rs4986791 (T399I), by TaqMan Real-Time PCR Assays. Kaplan-Meier survival curves were compared by the log-rank test. TLR3 polymorphism L412F was associated with a higher mitotic index (P = 0.035). TLR4 D299G and T399I polymorphisms were associated with indicators of melanoma severity, nodal metastases (P = 0.005 and P = 0.007, respectively) and advanced stage III (P = 0.005 and P = 0.004, respectively). Cox regression analysis showed that the presence of tumor-infiltrating lymphocytes (TILs) predicted better overall survival (HR = 0.318; P = 0.004). TLR4 T399I polymorphism was significantly associated with worse survival, P = 0.025. The overall survival rates were significantly lower for patients carrying variant allele T of TLR4 T399I SNP (TC and TT genotypes combined) (P = 0.008, log-rank test), compared to wild-type genotype CC. Our findings indicate that TLR4 polymorphisms T399I (rs4986791) and D299G (rs4986790) could be potential prognostic and survival markers for melanoma patients.

RNF115 Inhibits the Post-ER Trafficking of TLRs and TLRs-Mediated Immune Responses by Catalyzing K11-Linked Ubiquitination of RAB1A and RAB13

The subcellular localization and intracellular trafficking of Toll-like receptors (TLRs) critically regulate TLRs-mediated antimicrobial immunity and autoimmunity. Here, it is demonstrated that the E3 ubiquitin ligase RNF115 inhibits the post-endoplasmic reticulum (ER) trafficking of TLRs and TLRs-mediated immune responses by catalyzing ubiquitination of the small GTPases RAB1A and RAB13. It is shown that the 14-3-3 chaperones bind to AKT1-phosphorylated RNF115 and facilitate RNF115 localizing on the ER and the Golgi apparatus. RNF115 interacts with RAB1A and RAB13 and catalyzes K11-linked ubiquitination on the Lys49 and Lys61 residues of RAB1A and on the Lys46 and Lys58 residues of RAB13, respectively. Such a modification impairs the recruitment of guanosine diphosphate (GDP) dissociation inhibitor 1 (GDI1) to RAB1A and RAB13, a prerequisite for the reactivation of RAB proteins. Consistently, knockdown of RAB1A and RAB13 in Rnf115^+/+ and Rnf115^-/- cells markedly inhibits the post-ER and the post-Golgi trafficking of TLRs, respectively. In addition, reconstitution of RAB1A^K49/61R or RAB13^K46/58R into Rnf115^+/+ cells but not Rnf115^-/- cells promotes the trafficking of TLRs from the ER to the Golgi apparatus and from the Golgi apparatus to the cell surface, respectively. These findings uncover a common and step-wise regulatory mechanism for the post-ER trafficking of TLRs.

Phytochemicals as PI3K/ Akt/ mTOR Inhibitors and Their Role in Breast Cancer Treatment

BACKGROUND

Breast cancer is the predominant form of cancer in women; various cellular pathways are involved in the initiation and progression of breast cancer. Among the various types of breast cancer that differ in their growth factor receptor status, PI3K/Akt signaling is a common pathway where all these converge. Thus, the PI3K signaling is of great interest as a target for breast cancer prevention; however, it is less explored.

OBJECTIVE

The present review is aimed to provide a concise outline of the role of PI3K/Akt/mTOR pathway in breast carcinogenesis and its progression events, including metastasis, drug resistance and stemness. The review emphasizes the role of natural and synthetic inhibitors of PI3K/Akt/m- TOR pathway in breast cancer prevention.

METHODS

The data were obtained from PubMed/Medline databases, Scopus and Google patent literature.

RESULTS

PI3K/Akt/mTOR signaling plays an important role in human breast carcinogenesis; it acts on the initiation and progression events associated with it. Numerous molecules have been isolated and identified as promising drug candidates by targeting the signaling pathway. Results from clinical studies confirm their application in the treatment of human breast cancer alone and in combination with classical chemotherapeutics as well as monoclonal antibodies.

CONCLUSION

PI3K/mTOR signaling blockers have evolved as promising anticancer agents by interfering breast cancer development and progression at various stages. Natural products and bioactive components are emerging as novel inhibitors of PI3K signaling and more research in this area may yield numerous drug candidates.